Semiconductor device, display device including the same

Abstract

A novel semiconductor device is provided. A semiconductor device includes a first transistor and a second transistor. The first transistor includes a first gate electrode, a first insulating film over the first gate electrode, a first oxide semiconductor film over the first insulating film, a first source electrode and a first drain electrode over the first oxide semiconductor film, a second insulating film over the first oxide semiconductor film, the first source electrode, and the first drain electrode, and a second gate electrode over the second insulating film. The second transistor includes the first drain electrode, a second insulating film over the first drain electrode, a second oxide semiconductor film over the second insulating film, a second source electrode and a second drain electrode over the second oxide semiconductor film, a third insulating film over the second oxide semiconductor film, the second source electrode, and the second drain electrode, and a third gate electrode over the third insulating film. The first oxide semiconductor film partially overlaps with the second oxide semiconductor film.

Description

TECHNICAL FIELD

[0001] One embodiment of the present application relates to a semiconductor device having an oxide semiconductor film and a display device including the semiconductor device.

[0002] Note that one embodiment of the present application is not limited to the above technical field. The technical field of one embodiment of the present application disclosed in this specification and the like relates to an object, a method, or a manufacturing method. The present application relates to a process, a machine, a product, or a composition of matter. In particular, one embodiment of the present application relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, a driving method thereof, and a manufacturing method thereof.

[0003] In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. A semiconductor element such as a transistor, a semiconductor circuit, an arithmetic device, and a memory device are each a kind of semiconductor device. An imaging device, a display device, a liquid crystal display device, a light-emitting device, an electro-optical device, a power generation device (including a thin-film solar cell, an organic thin-film solar cell, and the like), and an electronic device each include a semiconductor device in some cases. BACKGROUND

[0004] A technique for forming a transistor (also referred to as a field effect transistor (FET) or a thin film transistor (TFT)) using a semiconductor thin film formed over a substrate having an insulating surface has attracted attention. The transistor is widely applied to electronic devices such as integrated circuits (ICs) or image display devices (display devices). As a semiconductor thin film which can be used for a transistor, a semiconductor material typified by silicon is known, and an oxide semiconductor has also attracted attention.

[0005] For example, Patent Document 1 discloses a technique in which a plurality of memory cells each including a first transistor including an oxide semiconductor film and a second transistor including an oxide semiconductor film are stacked to reduce the area of each memory cell.

[0006] Patent Document 2 discloses a technique in which a pixel portion including a plurality of pixels arranged in a two-dimensional manner and a driver circuit portion which drives the plurality of pixels are provided, and the area of the driver circuit portion in the periphery of the pixel portion is reduced by stacking a first layer including the driver circuit portion and a second layer including the pixel portion.

[0007] [REFERENCE LITERATURE]

[0008] [Patent Document 1]

[0009] [Patent Document 1] Japanese Published Patent Application No. 2013-138191

[0010] [Patent Document 2] Japanese Published Patent Application No. 2015-194577 SUMMARY

[0011] As described in Patent Documents 1 and 2, the area of a transistor can be reduced by stacking a plurality of transistors. On the other hand, stacking a plurality of transistors leads to an increase in the number of masks or the number of manufacturing steps.

[0012] In view of the above problems, an object of one embodiment of the present application is to provide a semiconductor device in which a plurality of transistors are stacked, which has a small number of masks or a small number of manufacturing steps. Another object of one embodiment of the present application is to provide a semiconductor device in which a plurality of transistors including an oxide semiconductor film are stacked, which has a small number of masks or a small number of manufacturing steps. Another object of one embodiment of the present application is to provide a novel semiconductor device.

[0013] Note that the description of the above object does not exclude the existence of other objects. In one embodiment of the present application, all the above objects are not necessarily achieved. An object other than the above objects is apparent from the description or the like and can be extracted from the description or the like.

[0014] One embodiment of the present application is a semiconductor device including a first transistor and a second transistor. The first transistor includes a first gate electrode, a first insulating film over the first gate electrode, a first oxide semiconductor film over the first insulating film, a first source electrode over the first oxide semiconductor film, a first drain electrode over the first oxide semiconductor film, a second insulating film over the first oxide semiconductor film, the first source electrode, and the first drain electrode, and a second gate electrode over the second insulating film. The second transistor includes one of the first source electrode and the first drain electrode, a second insulating film over the first drain electrode, a second oxide semiconductor film over the second insulating film, a second source electrode over the second oxide semiconductor film, a second drain electrode over the second oxide semiconductor film, a third insulating film over the second oxide semiconductor film, the second source electrode, and the second drain electrode, and a third gate electrode over the third insulating film. The first oxide semiconductor film and the second oxide semiconductor film partially overlap with each other.

[0015] Another embodiment of the present application is a semiconductor device including a first transistor and a second transistor. The first transistor includes a first gate electrode; a first insulating film over the first gate electrode; a first oxide semiconductor film over the first insulating film; a first source electrode over the first oxide semiconductor film; a first drain electrode over the first oxide semiconductor film; a second insulating film over the first oxide semiconductor film, the first source electrode, and the first drain electrode; and a second gate electrode over the second insulating film. The second transistor includes a third gate electrode over the first insulating film; a second insulating film over the third gate electrode; a second oxide semiconductor film over the second insulating film and including a channel region, a source region, and a drain region; a third insulating film in contact with the channel region; a fourth gate electrode in contact with the third insulating film; a fourth insulating film in contact with the source region, the drain region, and the fourth gate electrode; a second source electrode electrically connected to the source region; and a second drain electrode electrically connected to the drain region. The first oxide semiconductor film and the second oxide semiconductor film partially overlap with each other.

[0016] In the above embodiment, it is preferable that the first gate electrode and the second gate electrode be connected together in openings of the first insulating film and the second insulating film, and have a region positioned outside side end portions of the first oxide semiconductor film.

[0017] In the above embodiment, it is preferable that the first oxide semiconductor film and / or the second oxide semiconductor film include In, Zn, and M (M is Al, Ga, Y, or Sn).

[0018] In the above embodiment, it is preferable that the atomic ratio of In:M:Zn be approximately 4:2:3, and in the case where In is 4, M be greater than or equal to 1.5 and less than or equal to 2.5, and Zn be greater than or equal to 2 and less than or equal to 4.

[0019] In the above embodiment, it is preferable that one or both of the first oxide semiconductor film and the second oxide semiconductor film include a crystal portion having c-axis alignment.

[0020] Another embodiment of the present application is a semiconductor device including a first transistor and a second transistor. The first transistor includes a first oxide semiconductor film, a first insulating film over the first oxide semiconductor film, a first conductive film overlapping with the first oxide semiconductor film with a region of the first insulating film interposed therebetween, a second insulating film over the first oxide semiconductor film and the first conductive film, a second conductive film over the first oxide semiconductor film, a third conductive film over the first oxide semiconductor film, and a third insulating film over the first oxide semiconductor film, the second conductive film, and the third conductive film. The second transistor includes the third conductive film, a third insulating film over the third conductive film, a second oxide semiconductor film over the third insulating film, a fourth conductive film over the second oxide semiconductor film, and a fifth conductive film over the second oxide semiconductor film. The first oxide semiconductor film includes a channel region in contact with the first insulating film, a source region in contact with the second insulating film, and a drain region in contact with the second insulating film. The first oxide semiconductor film and the second oxide semiconductor film partially overlap with each other.

[0021] Another embodiment of the present application is a semiconductor device including a first transistor and a second transistor. The first transistor includes a first oxide semiconductor film, a first insulating film over the first oxide semiconductor film, a first conductive film overlapping with the first oxide semiconductor film with a region of the first insulating film interposed therebetween, a second insulating film over the first oxide semiconductor film and the first conductive film, a second conductive film over the first oxide semiconductor film, a third conductive film over the first oxide semiconductor film, and a third insulating film over the first oxide semiconductor film, the second conductive film, and the third conductive film. The second transistor includes the third conductive film, a third insulating film over the third conductive film, a second oxide semiconductor film over the third insulating film, a fourth conductive film over the second oxide semiconductor film, a fifth conductive film over the second oxide semiconductor film, a fourth insulating film over the second oxide semiconductor film, the fourth conductive film, and the fifth conductive film, and a sixth conductive film overlapping with the second oxide semiconductor film with a region of the fourth insulating film interposed therebetween. The first oxide semiconductor film includes a channel region in contact with the first insulating film, a source region in contact with the second insulating film, and a drain region in contact with the second insulating film. The first oxide semiconductor film and the second oxide semiconductor film partially overlap with each other.

[0022] Another embodiment of the present application is a semiconductor device including a first transistor and a second transistor. The first transistor includes a first oxide semiconductor film, a first insulating film over the first oxide semiconductor film, a first conductive film overlapping with the first oxide semiconductor film with the first insulating film interposed therebetween, a second insulating film over the first oxide semiconductor film and the first conductive film, a second conductive film over the first oxide semiconductor film, a third conductive film over the first oxide semiconductor film, and a third insulating film over the first oxide semiconductor film, the second conductive film, and the third conductive film. The first oxide semiconductor film includes a channel region in contact with the first insulating film, a source region in contact with the second insulating film, and a drain region in contact with the second insulating film. The second transistor includes the third conductive film, a fourth insulating film over the third conductive film, a second oxide semiconductor film over the fourth insulating film, a fourth conductive film over the second oxide semiconductor film, a fifth conductive film over the second oxide semiconductor film, a fourth insulating film over the second oxide semiconductor film, a sixth conductive film overlapping with the second oxide semiconductor film with the fourth insulating film interposed therebetween, and a fifth insulating film over the second oxide semiconductor film and the sixth conductive film. The second oxide semiconductor film includes a channel region in contact with the fourth insulating film, a source region in contact with the fifth insulating film, and a drain region in contact with the fifth insulating film. The first oxide semiconductor film and the second oxide semiconductor film partially overlap with each other.

[0023] In the above embodiment, it is preferable that the first oxide semiconductor film and / or the second oxide semiconductor film contain In, M (M is Al, Ga, Y, or Sn), and Zn.

[0024] In the above embodiment, it is preferable that the atomic ratio of the oxide semiconductor film be In:M:Zn = 4:2:3 or closer, and in the case where In is 4, M be 1.5 or more and 2.5 or less, and Zn be 2 or more and 4 or less.

[0025] In the above embodiment, it is preferable that the first oxide semiconductor film and / or the second oxide semiconductor film include a crystal portion having c-axis alignment.

[0026] Another embodiment of the present application is a display device including the semiconductor device described in any of the above embodiments, and a light-emitting element. It is preferable that the light-emitting element contain an organic compound, and the organic compound contain a high molecular compound.

[0027] Another embodiment of the present application is a display module including the display device described above and a touch sensor. Another embodiment of the present application is an electronic device including the semiconductor device described in any of the above embodiments, the display device described above, or the display module described above, and an operation key or a battery.

[0028] According to one embodiment of the present application, a semiconductor device in which a plurality of transistors are stacked can be manufactured with a small number of masks or manufacturing steps. According to one embodiment of the present application, a semiconductor device in which a plurality of transistors including an oxide semiconductor film are stacked can be manufactured with a small number of masks or manufacturing steps. According to one embodiment of the present application, a novel semiconductor device can be provided.

[0029] Note that the description is not intended to limit other effects. One embodiment of the present application does not necessarily achieve all the effects. Effects other than those described above will be apparent to those skilled in the art from the description of the specification, the attached drawings, the claims, and the like. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1A and Figure 1B is a top view and a cross-sectional view of a semiconductor device;

[0031] Figure 2 a circuit of a semiconductor device is described;

[0032] Figure 3 is a cross-sectional view of a semiconductor device;

[0033] Figure 4A and Figure 4B is a cross-sectional view of a semiconductor device;

[0034] Figure 5 is a cross-sectional view of a semiconductor device;

[0035] Figure 6A and Figure 6B is a cross-sectional view of a semiconductor device;

[0036] Figure 7A and Figure 7B a band is described;

[0037] Figure 8A and Figure 8B is a top view and a cross-sectional view of a method for manufacturing a semiconductor device;

[0038] Figure 9A and Figure 9B is a top view and a cross-sectional view of a method for manufacturing a semiconductor device;

[0039] Figure 10A and Figure 10B is a top view and a cross-sectional view of a method for manufacturing a semiconductor device;

[0040] Figure 11A and Figure 11B is a top view and a cross-sectional view of a method for manufacturing a semiconductor device;

[0041] Figure 12A and Figure 12B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0042] Figure 13A and Figure 13B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0043] Figure 14A and Figure 14B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0044] Figure 15A and Figure 15B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0045] Figure 16A and Figure 16B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0046] Figure 17A and Figure 17B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0047] Figure 18A and Figure 18B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0048] Figure 19A and Figure 19B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0049] Figure 20A and Figure 20B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0050] Figure 21A and Figure 21B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0051] Figure 22A and Figure 22B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0052] Figure 23A and Figure 23B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0053] Figure 24A and Figure 24B are cross-sectional views illustrating a method for manufacturing a semiconductor device;

[0054] Figure 25A and Figure 25B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0055] Figure 26A and Figure 26B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0056] Figure 27A and Figure 27B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0057] Figure 28A and Figure 28B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0058] Figure 29A and Figure 29B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0059] Figure 30A and Figure 30B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0060] Figure 31 is a circuit of a semiconductor device;

[0061] Figure 32 is a cross-sectional view of a semiconductor device;

[0062] Figure 33 is a cross-sectional view of a semiconductor device;

[0063] Figure 34A and Figure 34B is a cross-sectional view of a semiconductor device;

[0064] Figure 35A and Figure 35B is a band gap;

[0065] Figure 36A and Figure 36B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0066] Figure 37A and Figure 37B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0067] Figure 38A and Figure 38B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0068] Figure 39A and Figure 39B is a plan view and a cross-sectional view illustrating a manufacturing method of a semiconductor device;

[0069] Figure 40A and Figure 40B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0070] Figure 41A and Figure 41B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0071] Figure 42A and Figure 42B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0072] Figure 43A and Figure 43B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0073] Figure 44A and Figure 44B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0074] Figure 45A and Figure 45B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0075] Figure 46A and Figure 46B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0076] Figure 47A and Figure 47B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0077] Figure 48A and Figure 48B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0078] Figure 49A and Figure 49B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0079] Figure 50A and Figure 50B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0080] Figure 51A and Figure 51B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0081] Figure 52A and Figure 52B are top view and cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0082] Figure 53A and Figure 53Bis a top view and a cross-sectional view illustrating a method for manufacturing a semiconductor device;

[0083] Figure 54 is a cross-sectional schematic view of a light emitting element;

[0084] Figures 55A to 55D is a cross-sectional schematic view illustrating a method for manufacturing an EL layer;

[0085] Figure 56 is a schematic view illustrating a liquid droplet ejecting apparatus;

[0086] Figures 57A to 57C A range of the atomic ratio of an oxide semiconductor is shown;

[0087] Figure 58 is a view illustrating a crystal structure of InMZnO4;

[0088] Figure 59 is a view illustrating a band of a transistor in which an oxide semiconductor is used for a channel region;

[0089] Figures 60A to 60E A view of structure analysis by XRD of a CAAC-OS and a single crystal oxide semiconductor and a selected-area electron diffraction pattern of a CAAC-OS are shown;

[0090] Figures 61A to 61E A cross-sectional TEM image, a plan view TEM image, and a view obtained by image analysis of a CAAC-OS are shown;

[0091] Figures 62A to 62D An electron diffraction pattern and a cross-sectional TEM image of an nc-OS are shown;

[0092] Figure 63A and Figure 63B A cross-sectional TEM image of an a-like OS is shown;

[0093] Figure 64 A change in a crystal portion caused by electron irradiation of an In-Ga-Zn oxide is shown;

[0094] Figure 65 is a top view illustrating one embodiment of a display device;

[0095] Figure 66 is a cross-sectional view illustrating one embodiment of a display device;

[0096] Figure 67 A cross-sectional view illustrating one embodiment of a display device is shown;

[0097] Figure 68 is a block diagram illustrating a display device;

[0098] Figure 69 A display module is described;

[0099] Figures 70A to 70E An electronic device is described;

[0100] Figures 71A to 71G An electronic device is described;

[0101] Figure 72A and Figure 72B is a perspective view illustrating a display device. DETAILED DESCRIPTION

[0102] Embodiments will now be described with reference to the drawings, which are provided for the purpose of illustration only and are not intended to limit the present application in any way. The present application can be carried out in many different ways and is therefore not limited to the embodiments described hereinbelow.

[0103] In the drawings, the size, the thickness or the region of each constituent element is sometimes exaggerated, and the like for the purpose of clarity. Thus, one embodiment of the present application is not limited to the size or the region illustrated in the drawings. In addition, the drawings are schematically shown an ideal example, and one embodiment of the present application is not limited to the shape or the value illustrated in the drawings.

[0104] The ordinal numbers "first", "second", "third", and the like in the present specification are used for the purpose of explanation and do not limit the number in any case.

[0105] In the present specification, for the purpose of convenience in explanation, words of "above", "below", and the like are used to describe the positional relationship of the constituent elements with reference to the drawings. The positional relationship of the constituent elements is appropriately changed depending on the direction of each constituent element described. Thus, it is not limited to the words described in the specification, and can be appropriately changed depending on the situation.

[0106] In the present specification and the like, a transistor refers to an element including at least three terminals of a gate, a drain, and a source. The transistor has a channel region between the drain and the source, and current can flow through the drain, the channel region, and the source. Note that in the present specification and the like, the channel region refers to a region where current flows.

[0107] In the case of using a transistor having an opposite polarity or in the case where the direction of current flowing in a circuit is changed, the functions of the "source" and the "drain" are sometimes switched with each other. Thus, the "source" and the "drain" can be switched with each other in the present specification and the like.

[0108] In this specification and the like, "electrically connected" includes the case where elements are connected through an element having some function of electricity. An element having some function of electricity is not particularly limited as long as it can transmit and receive an electric signal between elements to be connected. Examples of the element having some function of electricity include not only an electrode and a wiring but also a switching element such as a transistor, a resistor, an inductor, a capacitor, and an element having another function.

[0109] In this specification and the like, "parallel" means a state where an angle formed between two straight lines is greater than or equal to -10° and less than or equal to 10°, and thus includes a state where the angle is greater than or equal to -5° and less than or equal to 5°. In addition, "perpendicular" means a state where an angle formed between two straight lines is greater than or equal to 80° and less than or equal to 100°, and thus includes a state where the angle is greater than or equal to 85° and less than or equal to 95°.

[0110] In this specification and the like, "film" and "layer" can be interchanged with each other. For example, "a conductive layer" can be replaced with "a conductive film". Similarly, "an insulating film" can be replaced with "an insulating layer".

[0111] In this specification and the like, in the case where there is no particular description, an off-state current refers to a drain current when a transistor is in an off state (also referred to as a non-conducting state, a blocking state). In the case where there is no particular description, an off state of an n-channel transistor refers to a state where a voltage (V gs : gate-source voltage) between a gate and a source is lower than a threshold voltage V th , and an off state of a p-channel transistor refers to a state where the voltage V gs between the gate and the source is higher than the threshold voltage V th . For example, the off-state current of the n-channel transistor refers to a drain current when the gate-source voltage V gs is lower than the threshold voltage V th .

[0112] The off-state current of the transistor is sometimes dependent on V gs . Thus, "the off-state current of the transistor is I or less" sometimes means that there is V gs which makes the off-state current of the transistor I or less. The off-state current of the transistor sometimes refers to an off-state current in an off state at a predetermined V gs , an off state at V gs within a predetermined range, or an off state at V gs at which sufficiently low off-state current can be obtained.

[0113] As one example, an n-channel transistor whose threshold voltage V th is 0.5 V and V gs1 x 10 -9 A, V gs 1 x 10 -13 A, V gs 1 x 10 -19 A, V gs 1 x 10 -22 A. At V gs 1 x 10 gs A, V -19 1 x 10 -19 A, V -22 1 x 10 gs A, V -22 1 x 10

[0114] In this specification and the like, the off-state current of a transistor having a channel width W is sometimes expressed in terms of a current value per channel width W, or the off-state current of a transistor having a channel width W is sometimes expressed in terms of a current value per predetermined channel width (e.g., 1 μm). In the latter case, the off-state current is sometimes expressed in terms of current per length (e.g., A / μm).

[0115] The off-state current of a transistor is sometimes dependent on temperature. In this specification, unless specifically noted otherwise, the off-state current is sometimes the off-state current at room temperature, 60 °C, 85 °C, 95 °C, or 125 °C. Alternatively, the off-state current is sometimes the off-state current at a temperature at which reliability of a semiconductor device including the transistor or the like is ensured or at a temperature at which a semiconductor device including the transistor or the like is used (e.g., a temperature range from 5 °C to 35 °C). The case where the off-state current of a transistor is I or less means that there is a voltage V gs at which the off-state current of the transistor becomes I or less at room temperature, 60 °C, 85 °C, 95 °C, 125 °C, a temperature at which reliability of a semiconductor device including the transistor is ensured, or a temperature at which a semiconductor device including the transistor or the like is used (e.g., a temperature range from 5 °C to 35 °C).

[0116] The off-state current of a transistor is sometimes dependent on the voltage V ds between a drain and a source. In this specification, unless specifically noted otherwise, the off-state current is sometimes the off-state current at V dsThe off-state current at the time when V is 0.1 V, 0.8 V, 1 V, 1.2 V, 1.8 V, 2.5 V, 3 V, 3.3 V, 10 V, 12 V, 16 V, or 20 V. Alternatively, the off-state current is sometimes V at which the reliability of a semiconductor device including the transistor is ensured ds Alternatively, V at which the off-state current is used for the semiconductor device or the like ds The off-state current of the transistor is I at V ds The off-state current of the transistor is I at V at which the reliability of a semiconductor device including the transistor or the like is ensured ds Alternatively, V at which the off-state current is used for the semiconductor device or the like ds The off-state current of the transistor is I at V gs .

[0117] In the above description of the off-state current, the drain can be replaced with the source. That is, the off-state current is sometimes referred to as a current flowing through the source when the transistor is in an off state.

[0118] In this specification and the like, "leakage current" sometimes means the same as the off-state current. In this specification and the like, the off-state current is sometimes referred to as a current flowing between the source and the drain when the transistor is in an off state, for example.

[0119] In this specification and the like, the threshold voltage of a transistor refers to a gate voltage (V g ) at which a channel is formed in the transistor. Specifically, in a graph in which the horizontal axis represents a gate voltage (Vg) and the vertical axis represents the square root of a drain current (Id), the threshold voltage of the transistor is sometimes referred to as a gate voltage (V d ) at which a straight line obtained by extrapolating a tangent line with the highest gradient in a plot (Vg-√Id characteristic) and a point at which the square root of the drain current (Id) is 0 (Id is 0 A) intersect with each other. Alternatively, the threshold voltage of the transistor is sometimes referred to as a gate voltage (V g ) at which the value of I d [A] x L [μm] / W [μm] is 1 x 10 -9 [A] when L is a channel length and W is a channel width. g

[0120] ​In this specification and the like, a "semiconductor" has characteristics of an "insulator" in some cases, for example, when the conductivity is sufficiently low. In addition, the border between a "semiconductor" and an "insulator" is not clear, and thus the "semiconductor" and the "insulator" cannot be precisely distinguished from each other in some cases. Thus, the "semiconductor" in this specification or the like can be alternatively called an "insulator" in some cases. Similarly, the "insulator" in this specification or the like can be alternatively called a "semiconductor" in some cases. Furthermore, the "insulator" in this specification or the like can be alternatively called a "semi-insulator" in some cases.

[0121] In this specification and the like, a "semiconductor" has characteristics of a "conductor" in some cases, for example, when the conductivity is sufficiently high. In addition, the border between a "semiconductor" and a "conductor" is not clear, and thus the "semiconductor" and the "conductor" cannot be precisely distinguished from each other in some cases. Thus, the "semiconductor" in this specification or the like can be alternatively called a "conductor" in some cases. Similarly, the "conductor" in this specification or the like can be alternatively called a "semiconductor" in some cases.

[0122] In this specification and the like, an impurity of a semiconductor refers to an element other than the main components of the semiconductor. For example, an element having a concentration lower than 0.1 atomic% is an impurity. If a semiconductor contains an impurity, a density of states (DOS) can be formed in the semiconductor, a carrier mobility can be decreased, or crystallinity can be decreased. In the case of an oxide semiconductor, examples of impurities which change the characteristics of the semiconductor are Group 1 elements, Group 2 elements, Group 14 elements, Group 15 elements, and transition metals other than the main components, and typical examples are hydrogen (included in water), lithium, sodium, silicon, boron, phosphorus, carbon, and nitrogen. In an oxide semiconductor, oxygen defects are sometimes generated due to the inclusion of impurities such as hydrogen. In the case where a semiconductor contains silicon, examples of impurities which change the characteristics of the semiconductor are oxygen, Group 1 elements other than hydrogen, Group 2 elements, Group 13 elements, and Group 15 elements.

[0123] Embodiment 1

[0124] In this embodiment, reference is made to Figure 1A and Figures 1B to 17A and Figure 17B A semiconductor device and a method for manufacturing a semiconductor device of one embodiment of the present application will be described.

[0125] <1-1. Structure Example 1 of Semiconductor Device>

[0126] Figure 1A is a top view of a semiconductor device 100 of one embodiment of the present application. Figure 1B is a cross-sectional view along the dotted line A1-A2 in Figure 1A In addition, in Figure 1BA cross section in a channel length (L) direction of the transistor Tr1 and a cross section in a channel length (L) direction of the transistor Tr2.

[0127] Further, in Figure 1A , a part of the constituent elements of the semiconductor device 100 (e.g., an insulating film used as a gate insulating film) and a part of the symbols of the constituent elements are not shown for convenience. Note that in the top view of the semiconductor device later, a part of the constituent elements and a part of the symbols of the constituent elements are not shown at times as well. Figure 1A Similarly, a part of the constituent elements and a part of the symbols of the constituent elements are not shown.

[0128] Figure 1A and Figure 1B The semiconductor device 100 illustrated in

[0129] Since the transistor Tr1 at least partially overlaps with the transistor Tr2, the area of the transistor can be reduced.

[0130] The transistor Tr1 includes a conductive film 104 over a substrate 102; an insulating film 106 over the substrate 102 and the conductive film 104; an oxide semiconductor film 108 over the insulating film 106; a conductive film 112a over the oxide semiconductor film 108; a conductive film 112b over the oxide semiconductor film 108; an insulating film 114 over the oxide semiconductor film 108, the conductive film 112a, and the conductive film 112b; an insulating film 116 over the insulating film 114; and a conductive film 122c over the insulating film 116.

[0131] The transistor Tr2 includes the conductive film 112b; the insulating film 114 over the conductive film 112b; the insulating film 116 over the insulating film 114; an oxide semiconductor film 128 over the insulating film 116; a conductive film 122a over the oxide semiconductor film 128; a conductive film 122b over the oxide semiconductor film 128; an insulating film 124 over the oxide semiconductor film 128, the conductive film 122a, and the conductive film 122b; an insulating film 126 over the insulating film 124; and a conductive film 130 over the insulating film 126. Further, the conductive film 130 is connected to the conductive film 122a through an opening 182 provided in the insulating films 124 and 126.

[0132] As illustrated in Figure 1A and Figure 1B The oxide semiconductor film 108 and the oxide semiconductor film 128 partially overlap with each other. Figure 1A and Figure 1BAs shown in FIG. 1, it is preferable that the channel region formed in the oxide semiconductor film 108 of the transistor Trl does not overlap with the channel region formed in the oxide semiconductor film 128 of the transistor Tr2.

[0133] If the channel region of the transistor Trl overlaps with the channel region of the transistor Tr2, one transistor in operation sometimes affects the other transistor. To avoid the negative influence, a structure in which the interval between the transistor Trl and the transistor Tr2 is increased, or a structure in which a conductive film is provided between the transistor Trl and the transistor Tr2, or the like can be used. However, in the case where the former structure is used, the thickness of the semiconductor device is increased. Thus, for example, when the semiconductor device 100 is formed over a flexible substrate or the like, a problem such as bendability is sometimes caused. In the case where the latter structure is used, there is a problem in that a process of forming a conductive film is needed and the thickness of the semiconductor device is increased.

[0134] On the other hand, in the semiconductor device 100 of one embodiment of the present application, the transistor Trl and the transistor Tr2 overlap with each other, and the channel regions of the transistors do not overlap with each other. Further, since part of each of the oxide semiconductor films forming the channel regions overlaps with each other, the area of the transistors can be appropriately reduced.

[0135] Further, the oxide semiconductor film 108 and the oxide semiconductor film 128 each include In, M (M is Al, Ga, Y, or Sn), and Zn. For example, the oxide semiconductor film 108 and the oxide semiconductor film 128 each preferably have a region in which the atomic ratio of In is higher than that of M. Note that the semiconductor device of one embodiment of the present application is not limited thereto, and can have a region in which the atomic ratio of In is lower than that of M, or can have a region in which the atomic ratio of In is equal to that of M.

[0136] It is preferable that the composition of the oxide semiconductor film 108 be the same as or substantially the same as that of the oxide semiconductor film 128. When the composition of the oxide semiconductor film 108 is the same as that of the oxide semiconductor film 128, the manufacturing cost can be reduced. Note that the semiconductor device of one embodiment of the present application is not limited thereto, and the composition of the oxide semiconductor film 108 can be different from that of the oxide semiconductor film 128.

[0137] When the oxide semiconductor film 108 and the oxide semiconductor film 128 each have a region in which the atomic ratio of In is higher than that of M, the field-effect mobility of the transistor Trl and the transistor Tr2 can be increased. Specifically, one or both of the field-effect mobilities of the transistor Trl and the transistor Tr2 can exceed 10 cm 2 / Vs, preferably, 30 cm 2 / Vs.

[0138] For example, when the aforementioned high field-effect mobility transistor is used in the gate driver of a display device to generate gate signals, the display device can have a narrow bezel. When the aforementioned high field-effect mobility transistor is used in the source driver (especially the demultiplexer connected to the output terminal of the shift register included in the source driver) of the display device to supply signals from signal lines, the number of wiring connections to the display device can be reduced. Furthermore, when the aforementioned high field-effect mobility transistor is used in one or both of the selection transistor and drive transistor of the pixel circuit included in the display device, the display quality of the display device can be improved.

[0139] Figure 1A and Figure 1B The semiconductor device 100 shown can be suitably used in the pixel circuit of a display device. Figure 1A and Figure 1B The layout shown can increase the pixel density of a display device. For example, even if the pixel density of the display device exceeds 1000 ppi (pixels per inch) or 2000 ppi, by... Figure 1A and Figure 1B The layout shown can also increase the pixel aperture ratio. Note that ppi is a unit that represents the number of pixels per inch.

[0140] <1-2. Pixel Circuit of Display Device>

[0141] Reference Figure 2 To the general Figure 1A and Figure 1B An example of the semiconductor device 100 being used in the pixel circuit of a display device will be described.

[0142] Figure 2 This is a circuit diagram illustrating an example of using a semiconductor device 100 in a pixel circuit of a display device.

[0143] Figure 2 The semiconductor device 100 shown includes: transistor Tr1; transistor Tr2; capacitor Cs1; and light-emitting element 160. Note that... Figure 2 An example is shown where two semiconductor devices 100 are adjacent in the column direction. The semiconductor devices 100 are used as pixels (also referred to as sub-pixels). Although Figure 1A and Figure 1B The capacitor Cs1 is not shown in the figure, but it can be formed by the parasitic capacitance between the conductive film 112b included in transistor Tr1 and the conductive film 122b included in transistor Tr2.

[0144] Figure 2The circuit diagram includes: data lines DL_Y-1 for input data signals to pixels; data lines DL_Y for input data signals to adjacent pixels; anode lines ANODE_X-1 for supplying potential to light-emitting elements; anode lines ANODE_X for supplying potential to adjacent light-emitting elements; and scan lines GL_X for supplying scan signals to pixels.

[0145] One of the source and drain electrodes of transistor Tr1 is electrically connected to the data line DL_Y-1. The first and second gate electrodes of transistor Tr1 are electrically connected to the scan line GL_X. Transistor Tr1 controls the writing of data signals by being in an on or off state.

[0146] One electrode of capacitor Cs1 is electrically connected to the other of the source and drain electrodes of transistor Tr1. The other electrode of capacitor Cs1 is electrically connected to the second gate electrode (also known as the back gate electrode) of transistor Tr2. Capacitor Cs1 functions as a storage capacitor to retain the data being written.

[0147] One of the source and drain electrodes of transistor Tr2 is electrically connected to the anode line ANODE_X-1.

[0148] One electrode of the pair of electrodes of the light-emitting element 160 is electrically connected to the other of the source and drain electrodes of the transistor Tr2, and the other electrode of the light-emitting element 160 is electrically connected to the cathode wire CATHODE. In addition, one electrode of the pair of electrodes of the light-emitting element 160 is electrically connected to the other of the pair of electrodes of the capacitor Cs1.

[0149] The above structure is to Figure 1A and Figure 1B The semiconductor device 100 shown is used as an example of a pixel in a display device.

[0150] <1-3. Structure of Semiconductor Devices>

[0151] Again, regarding Figure 1A and Figure 1B The semiconductor device 100 shown will be described in detail. Figure 1A and Figure 1B When the semiconductor device 100 shown is used for pixels in a display device, for example, the channel length (L) and channel width (W) of the transistor, as well as the line width of the wiring and electrodes connected to the transistor, can be larger. For example, when... Figure 1A and Figure 1B When transistors Tr1 and Tr2 are arranged in an overlapping manner as shown, the line width can be increased, etc., compared with the case where transistors Tr1 and Tr2 are arranged on the same plane, so the non-uniformity of the processing dimensions can be reduced.

[0152] Furthermore, one or both of the conductive and insulating films can be used together between transistors Tr1 and Tr2, thus reducing the number of masks or processes.

[0153] For example, in transistor Tr1, conductive film 104 is used as the first gate electrode, conductive film 112a as the source electrode, conductive film 112b as the drain electrode, and conductive film 122c as the second gate electrode. Furthermore, in transistor Tr1, insulating film 106 is used as the first gate insulating film, and insulating films 114 and 116 are used as the second gate insulating films. In transistor Tr2, conductive film 112b is used as the first gate electrode, conductive film 122a as the source electrode, conductive film 122b as the drain electrode, and conductive film 130 as the second gate electrode. Furthermore, in transistor Tr2, insulating films 114 and 116 are used as the first gate insulating films, and insulating films 124 and 126 are used as the second gate insulating films.

[0154] Note that in this specification, etc., insulating film 106 is sometimes referred to as the first insulating film, insulating films 114 and 116 as the second insulating film, and insulating films 124 and 126 as the third insulating film.

[0155] An insulating film 134 is disposed on the conductive film 130, and an insulating film 136 is disposed on the insulating film 134. An opening 184 is provided in the insulating films 134 and 136 to reach the conductive film 130. Furthermore, a conductive film 138 is disposed on the insulating film 136. In addition, the conductive film 138 is connected to the conductive film 130 in the opening 184.

[0156] Furthermore, an insulating film 140, an EL layer 142, and a conductive film 144 are disposed on the conductive film 138. The insulating film 140 covers a portion of the side end of the conductive film 138 and prevents short circuits between adjacent pixels. The EL layer 142 emits light. The conductive film 138, the EL layer 142, and the conductive film 144 constitute the light-emitting element 160. The conductive film 138 serves as one electrode of the light-emitting element 160. The conductive film 144 serves as the other electrode of the light-emitting element 160.

[0157] As described above, in one aspect of the semiconductor device of the present invention, multiple transistors are stacked, thereby reducing the area of ​​the transistors. Furthermore, since one or both of the insulating and conductive films are shared among the multiple transistors, the number of masks or processes can be reduced.

[0158] <1-4. Structure of the gate electrode>

[0159] like Figure 1A and Figure 1B As shown, both transistors Tr1 and Tr2 include two gate electrodes.

[0160] Here, the effects of the two gate electrodes are described with reference to FIG. 1B. Figure 1A Figure 1B Figure 3

[0161] In addition, the conductive film 122c used as the second gate electrode is electrically connected to the conductive film 104 used as the first gate electrode in the opening 181. Thus, the conductive film 104 and the conductive film 122c are supplied with the same potential. Further, as illustrated in FIG. 1B, the oxide semiconductor film 108 is positioned opposite to the conductive film 104 and the conductive film 122c and is sandwiched between the conductive films used as the two gate electrodes. The length of the conductive film 104 and the length of the conductive film 122c in the channel width direction are each greater than the length of the oxide semiconductor film 108 in the channel width direction. The entire oxide semiconductor film 108 overlaps with the conductive film 104 and the conductive film 122c with the insulating films 106, 114, and 116 interposed therebetween. Figure 3 is a cross-sectional view along the dotted line B1-B2 of FIG. 1B. Figure 1A includes a cross section in the channel width (W) direction of the transistor Trl. Figure 3 As illustrated in FIG. 1B, the conductive film 122c used as the second gate electrode is electrically connected to the conductive film 104 used as the first gate electrode in the opening 181. Thus, the conductive film 104 and the conductive film 122c are supplied with the same potential. Further, as illustrated in FIG. 1B, the oxide semiconductor film 108 is positioned opposite to the conductive film 104 and the conductive film 122c and is sandwiched between the conductive films used as the two gate electrodes. The length of the conductive film 104 and the length of the conductive film 122c in the channel width direction are each greater than the length of the oxide semiconductor film 108 in the channel width direction. The entire oxide semiconductor film 108 overlaps with the conductive film 104 and the conductive film 122c with the insulating films 106, 114, and 116 interposed therebetween.

[0162] Figure 3 As illustrated in FIG. 1B, the conductive film 122c used as the second gate electrode is electrically connected to the conductive film 104 used as the first gate electrode in the opening 181. Thus, the conductive film 104 and the conductive film 122c are supplied with the same potential. Further, as illustrated in FIG. 1B, the oxide semiconductor film 108 is positioned opposite to the conductive film 104 and the conductive film 122c and is sandwiched between the conductive films used as the two gate electrodes. The length of the conductive film 104 and the length of the conductive film 122c in the channel width direction are each greater than the length of the oxide semiconductor film 108 in the channel width direction. The entire oxide semiconductor film 108 overlaps with the conductive film 104 and the conductive film 122c with the insulating films 106, 114, and 116 interposed therebetween. Figure 3 In other words, the conductive film 104 and the conductive film 122c are connected in the opening 181 provided in the insulating films 106, 114, and 116 and have a region positioned outside the side end portion of the oxide semiconductor film 108.

[0163]

[0164] By employing the above structure, the oxide semiconductor film 108 included in the transistor Trl can be electrically surrounded by the electric field of the conductive film 104 and the conductive film 122c. The device structure of a transistor in which the first gate electrode and the second gate electrode like the transistor Trl electrically surround the oxide semiconductor film forming a channel region can be referred to as a surrounded channel (S-channel) structure.

[0165] Since the transistor Trl has the S-channel structure, the oxide semiconductor film 108 can be effectively subjected to the electric field for causing a channel by the conductive film 104 used as the first gate electrode. Thus, the current drivability of the transistor Trl is improved, so that a high on-state current characteristic can be obtained. Further, since the on-state current can be increased, the size of the transistor Trl can be reduced. In addition, since the transistor Trl has a structure in which the oxide semiconductor film 108 is surrounded by the conductive film 104 used as the first gate electrode and the conductive film 122c used as the second gate electrode, the mechanical strength of the transistor Trl can be improved. ​​​​​

[0166] Although the structure in which the first gate electrode and the second gate electrode are connected is described above, one embodiment of the present application is not limited to this. For example, as shown in the transistor Tr2, the conductive film 130 used as the second gate electrode can be electrically connected to the conductive film 122a used as the source electrode or the drain electrode of the transistor Tr2. Figure 1B

[0167] <1-5. Constituent elements of semiconductor device>

[0168] Next, the constituent elements of the semiconductor device of this embodiment are described in detail.

[0169] [Substrate]

[0170] There is no particular limitation on the material of the substrate 102 as long as it is a material having heat resistance that can withstand a subsequent heat treatment. For example, as the substrate 102, a glass substrate, a ceramic substrate, a quartz substrate, a sapphire substrate can be used. As the substrate 102, a single crystal semiconductor substrate or a polycrystal semiconductor substrate formed of silicon or silicon carbide, a compound semiconductor substrate formed of silicon germanium or the like, an SOI (Silicon On Insulator) substrate, or the like can be used. A substrate provided with a semiconductor element over the substrate can be used as the substrate 102. When a glass substrate is used as the substrate 102, a large-sized display device can be manufactured using a glass substrate with the following size: the 6th generation (1500 mm x 1850 mm), the 7th generation (1870 mm x 2200 mm), the 8th generation (2200 mm x 2400 mm), the 9th generation (2400 mm x 2800 mm), the 10th generation (2950 mm x 3400 mm).

[0171] As the substrate 102, a flexible substrate can be used, and the semiconductor device 100 can be provided directly over the flexible substrate. Alternatively, a separation layer can be provided between the substrate 102 and the semiconductor device 100. The separation layer can be used in the case where part or all of the semiconductor device formed over the separation layer is separated from the substrate 102 and transferred to another substrate. At this time, the semiconductor device 100 can be transferred to a substrate with low heat resistance or a flexible substrate.

[0172] [Conductive film]

[0173] ​The conductive films 104, 112a, 112b, 122a, 122b, 122c, 130, 138, and 144 can be formed using a metal element selected from chromium (Cr), copper (Cu), aluminum (Al), gold (Au), silver (Ag), zinc (Zn), molybdenum (Mo), tantalum (Ta), titanium (Ti), tungsten (W), manganese (Mn), nickel (Ni), iron (Fe), cobalt (Co), an alloy containing the above metal element as a component, or an alloy containing a combination of the above metal elements.

[0174] The conductive films 104, 112a, 112b, 122a, 122b, 122c, 130, 138, and 144 can be formed using an oxide conductor containing indium and tin, an oxide conductor containing tungsten and indium, an oxide conductor containing tungsten, indium, and zinc, an oxide conductor containing titanium and indium, an oxide conductor containing titanium, indium, and tin, an oxide conductor containing indium and zinc, an oxide conductor containing silicon, indium, and tin, an oxide conductor containing indium, gallium, and zinc, or the like.

[0175] In particular, the above oxide conductor is suitable for the conductive film 130. Here, the oxide conductor is described. In this specification and the like, the oxide conductor can be referred to as an OC (oxide conductor). For example, the oxide conductor is obtained by forming an oxygen deficiency in an oxide semiconductor and then adding hydrogen to the oxygen deficiency to form a donor level in the vicinity of a conduction band. As a result, the conductivity of the oxide semiconductor is increased and the oxide semiconductor becomes a conductor. The oxide semiconductor which becomes a conductor can be referred to as an oxide conductor. In general, an oxide semiconductor has a large energy gap and thus transmits visible light. The oxide conductor is an oxide semiconductor which has a donor level in the vicinity of a conduction band. Thus, the influence of absorption due to a donor level is small in the oxide conductor, and thus the oxide conductor has the same visible light-transmitting property as the oxide semiconductor.

[0176] As the conductive films 104, 112a, 112b, 122a, 122b, 122c, 130, 138, and 144, a Cu-X alloy film (X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti) can be used. By using a Cu-X alloy film, a thin film can be processed by a wet etching process, so that manufacturing cost can be reduced.

[0177] In particular, the above Cu-X alloy film is preferably used for one or more of the conductive film 104, the conductive film 112a, the conductive film 112b, the conductive film 122a, the conductive film 122b, and the conductive film 122c. As the Cu-X alloy film, a Cu-Mn alloy film is particularly preferable.

[0178] As the material of one or more of the conductive film 104, the conductive film 112a, the conductive film 112b, the conductive film 122a, the conductive film 122b, and the conductive film 122c, one or more of aluminum, copper, titanium, tungsten, tantalum, and molybdenum among the above metal elements is particularly preferable.

[0179] As one or more of the conductive film 104, the conductive film 112a, the conductive film 112b, the conductive film 122a, the conductive film 122b, and the conductive film 122c, a tantalum nitride film containing nitrogen and tantalum is preferably used. The tantalum nitride film has conductivity and has high barrier properties against copper and hydrogen. Since the amount of hydrogen released from the tantalum nitride film is small, the tantalum nitride film is most suitable for use as a metal film in contact with the oxide semiconductor film 108 or a metal film in the vicinity of the oxide semiconductor film 108.

[0180] [Insulating film]

[0181] As the insulating film 106, the insulating film 114, the insulating film 116, the insulating film 124, the insulating film 126, the insulating film 134, the insulating film 136, and the insulating film 140, an insulating layer including at least one of a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, a hafnium oxide film, a yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film formed by a plasma CVD method, a sputtering method, or the like can be used.

[0182] The insulating film 106 is used as a barrier film for inhibiting the passage of oxygen. For example, in the case where one or more of the insulating film 114, the insulating film 116, the oxide semiconductor film 108, the oxide semiconductor film 128, the insulating film 124, and the insulating film 126 have a region in which the oxygen content exceeds the stoichiometric composition (excess-oxygen region), the insulating film 106 can inhibit the passage of oxygen.

[0183] Further, the insulating film in contact with one or both of the oxide semiconductor film 108 and the oxide semiconductor film 128 is preferably an oxide insulating film and preferably has a region in which the oxygen content exceeds the stoichiometric composition (excess-oxygen region). In other words, the oxide insulating film having the excess-oxygen region is capable of releasing oxygen.

[0184] For example, the excess-oxygen region of the oxide insulating film can be formed by forming the insulating film in an oxygen atmosphere, performing heat treatment on the insulating film in an oxygen atmosphere after the formation of the insulating film, or adding oxygen to the insulating film after the formation of the insulating film. As a method for adding oxygen to the insulating film after the formation of the insulating film, plasma treatment is preferable.

[0185] The insulating film used as the gate insulating film of the transistor Trl and the transistor Tr2 can be formed using hafnium oxide. In the case where hafnium oxide is used as the insulating film used as the gate insulating film, the following effects are obtained.

[0186] The relative dielectric constant of hafnium oxide is higher than that of silicon oxide and silicon oxynitride. Thus, the thickness of the insulating film formed using hafnium oxide can be larger than that of the insulating film formed using silicon oxide, whereby the leakage current caused by a tunnel current can be reduced. That is, a transistor with small off-state current can be manufactured. Furthermore, hafnium oxide with a crystal structure has a higher relative dielectric constant than hafnium oxide with an amorphous structure. Thus, in order to manufacture a transistor with small off-state current, it is preferable to use hafnium oxide with a crystal structure. As examples of the crystal structure, monoclinic and cubic crystal systems can be given. Note that one embodiment of the present application is not limited to the above examples.

[0187] The insulating film used as the gate insulating film of the transistor Trl and the transistor Tr2 can be formed using silicon nitride. In the case where silicon nitride is used as the insulating film used as the gate insulating film, the following effects are obtained. The relative dielectric constant of silicon nitride is higher than that of silicon oxide and the thickness required for obtaining the same electrostatic capacity as silicon oxide is larger. Thus, the thickness of the gate insulating film can be increased. Thus, the electrostatic breakdown of the transistor Trl and the transistor Tr2 can be prevented by suppressing the decrease in the insulating resistance of the transistor Trl and the transistor Tr2 and increasing the insulating resistance.

[0188] The insulating films 114, 116, 124, and 126 have a function of supplying oxygen to the oxide semiconductor film 108 and / or the oxide semiconductor film 128. That is, the insulating films 114, 116, 124, and 126 contain oxygen. The insulating films 114 and 124 are insulating films through which oxygen can pass. Note that the insulating film 114 is also used as a film for preventing damage to the oxide semiconductor film 108 when the insulating film 116 is formed in a later step. The insulating film 124 is also used as a film for preventing damage to the oxide semiconductor film 128 when the insulating film 126 is formed in a later step.

[0189] As the insulating films 114 and 124, a silicon oxide film, a silicon oxynitride film, or the like having a thickness of greater than or equal to 5 nm and less than or equal to 150 nm, preferably greater than or equal to 5 nm and less than or equal to 50 nm can be used.

[0190] In addition, the amount of defects in the insulating films 114 and 124 is preferably small, and typically, the spin density of a signal due to a silicon dangling bond and appearing at g = 2.001 measured by electron spin resonance (ESR: electron spin resonance) is preferably 3 x 10 17 spins / cm 3 The following. This is because, if the defect density of the insulating films 114 and 124 is high, oxygen is bonded to the defects, and thus the amount of permeation of oxygen in the insulating film 114 is reduced.

[0191] The insulating films 114 and 124 can be formed using an oxide insulating film in which the state density due to nitrogen oxide is low. Note that the state density due to nitrogen oxide is sometimes formed between the energy (E V_OS ) of the valence band top of the oxide semiconductor film and the energy (E C_OS ) of the conduction band bottom. As the above oxide insulating film, a silicon oxynitride film in which the amount of release of nitrogen oxide is small, an aluminum oxynitride film in which the amount of release of nitrogen oxide is small, or the like can be used.

[0192] In addition, in thermal desorption spectroscopy (TDS), a silicon oxynitride film in which the amount of release of nitrogen oxide is small is a film in which the amount of release of ammonia is larger than that of nitrogen oxide, and typically, the amount of release of ammonia is 1 x 10 18 cm -3 or more and 5 x 10 19 cm -3 or less. Note that the above amount of release of ammonia is the total amount of ammonia released at a temperature in the range of 50 °C to 650 °C or 50 °C to 550 °C in TDS. The above amount of release of ammonia is the total amount of the amount of release of ammonia converted into ammonia molecules in TDS.

[0193] Nitrogen oxide (NO x x is greater than 0 and 2 or less, preferably 1 or more and 2 or less), typically NO2or NO, forms an energy level in the insulating films 114 and 124. The energy level is located in the energy gap of the oxide semiconductor films 108 and 128. Thus, when nitrogen oxide diffuses to the interface between the insulating film 114 and the oxide semiconductor film 108 or the interface between the insulating film 124 and the oxide semiconductor film 128, an electron on the side of the insulating film 114 or 124 is sometimes trapped by the energy level. As a result, the trapped electron remains near the interface between the insulating film 114 and the oxide semiconductor film 108 or the interface between the insulating film 124 and the oxide semiconductor film 128, and thus the threshold voltage of the transistor is shifted in the positive direction.

[0194] During the heat treatment, nitrogen oxides react with ammonia and oxygen. Because the nitrogen oxides contained in insulating films 114 and 124 react with the ammonia contained in insulating films 116 and 126 during the heat treatment, the amount of nitrogen oxides contained in insulating films 114 and 124 decreases. Therefore, electrons are less likely to be trapped at the interface between insulating film 114 and oxide semiconductor film 108, or at the interface between insulating film 124 and oxide semiconductor film 128.

[0195] By using the aforementioned oxide insulating film, insulating films 114 and 124 can reduce the drift of the threshold voltage of the transistor, thereby reducing the variation in the electrical characteristics of the transistor.

[0196] Through heat treatment during transistor manufacturing, typically above 300°C and below 350°C, ESR spectra of insulating films 114 and 124 below 100K revealed a first signal with g values ​​between 2.037 and 2.039, a second signal with g values ​​between 2.001 and 2.003, and a third signal with g values ​​between 1.964 and 1.966. The split widths between the first and second signals, and between the second and third signals, obtained through X-ray band ESR measurements, were approximately 5 mT. The sum of the spin densities of the first signal (g values ​​between 2.037 and 2.039), the second signal (g values ​​between 2.001 and 2.003), and the third signal (g values ​​between 1.964 and 1.966) was less than 1 × 10⁻⁶. 18 spins / cm 3 Typically 1×10 17 spins / cm 3 Above and below 1×10 18 spins / cm 3 .

[0197] In ESR spectra below 100 K, the sum of the spin densities of the first signal (g=2.037 to 2.039), the second signal (g=2.001 to 2.003), and the third signal (g=1.964 to 1.966) corresponds to the spin density originating from nitrogen oxides (NO). x The sum of the spin densities of signals (x > 0 and 2 or less, preferably 1 or more and 2 or less). Typical examples of nitrogen oxides include nitric oxide and nitrogen dioxide. It can be considered that the lower the total number of spin densities of the first signal with a g value of 2.037 or more and 2.039 or less, the second signal with a g value of 2.001 or more and 2.003 or less, and the third signal with a g value of 1.964 or more and 1.966 or less, the lower the nitrogen oxide content in the oxide insulating film.

[0198] The oxide insulating film has a nitrogen concentration of 6 x 10 20 atoms / cm 3 or more.

[0199] The oxide insulating film is formed by the PECVD method using silane and dinitrogen monoxide at a substrate temperature of 220°C or more and 350°C or less, and thus a dense and hard oxide insulating film can be formed.

[0200] The insulating films 116 and 126 are formed using an oxide insulating film having an oxygen content exceeding a stoichiometric composition. By heating, a part of the oxygen is released from the oxide insulating film having an oxygen content exceeding a stoichiometric composition. The amount of oxygen released from the oxide insulating film having an oxygen content exceeding a stoichiometric composition is 1.0 x 10 19 cm -3 or more, preferably 3.0 x 10 20 cm -3 or more. Note that the amount of oxygen released is the total amount of oxygen released at a temperature in the range of 50°C to 650°C or 50°C to 550°C in the heat treatment in the TDS. The amount of oxygen released is the total amount of oxygen released as oxygen molecules in the TDS.

[0201] As the insulating films 116 and 126, a silicon oxide film, a silicon oxynitride film, or the like having a thickness of 30 nm or more and 500 nm or less, preferably 50 nm or more and 400 nm or less can be used.

[0202] Further, it is preferable that the amount of defects in the insulating films 116 and 126 be small, and typically, the spin density of a signal attributed to a silicon dangling bond and appearing at g = 2.001 be lower than 1.5 x 10 18 spins / cm 3 , more preferably 1 x 10 18 spins / cm 3 or more.

[0203] Since the insulating films 114 and 116 and the insulating films 124 and 126 can be formed using insulating films containing the same kind of material, the interfaces of the insulating films 114 and 116 and the interfaces of the insulating films 124 and 126 are not always clearly confirmed. Thus, in this embodiment mode, the interfaces of the insulating films 114 and 116 and the interfaces of the insulating films 124 and 126 are indicated by dotted lines.

[0204] The insulating film 134 is used as a protective insulating film of the transistor Trl and the transistor Tr2.

[0205] The insulating film 134 contains one or both of hydrogen and nitrogen. In addition, the insulating film 134 contains nitrogen and silicon. The insulating film 134 has a function of blocking oxygen, hydrogen, water, alkali metals, alkaline earth metals, and the like. By providing the insulating film 134, diffusion of oxygen from the oxide semiconductor films 108 and 128 to the outside can be prevented, and diffusion of oxygen contained in the insulating films 114, 116, 124, and 126 to the outside can be prevented, and entry of hydrogen, water, and the like from the outside into the oxide semiconductor films 108 and 128 can be prevented.

[0206] The insulating film 134 can be formed using a nitride insulating film, for example. The nitride insulating film is formed using silicon nitride, silicon nitride oxide, aluminum nitride, aluminum nitride oxide, or the like.

[0207] [Oxide Semiconductor Film]

[0208] The oxide semiconductor films 108 and 128 can be formed using the above-described materials.

[0209] When the oxide semiconductor films 108 and 128 each contain an In-M-Zn oxide, the atomic ratio of the metal elements of a sputtering target used for forming the In-M-Zn oxide is preferably In > M. The atomic ratio of the metal elements of such a sputtering target is, for example, In:M:Zn = 2:1:3, In:M:Zn = 3:1:2, or In:M:Zn = 4:2:4.1.

[0210] When the oxide semiconductor film 108 and the oxide semiconductor film 128 each contain an In-M-Zn oxide, the atomic ratio of the metal elements of a sputtering target used for forming the In-M-Zn oxide is preferably In ≤ M. The atomic ratio of the metal elements of such a sputtering target is, for example, In:M:Zn = 1:1:1, In:M:Zn = 1:1:1.2, In:M:Zn = 1:3:2, In:M:Zn = 1:3:4, or In:M:Zn = 1:3:6.

[0211] When the oxide semiconductor film 108 and the oxide semiconductor film 128 each contain an In-M-Zn oxide, a sputtering target containing a polycrystalline In-M-Zn oxide is preferably used as the sputtering target. By using a sputtering target containing a polycrystalline In-M-Zn oxide, the oxide semiconductor films 108 and 128 each having crystallinity can be easily formed. Note that the atomic ratio of the metal elements in the formed oxide semiconductor films 108 and 128 varies within a range of ±40 % of the atomic ratio of the metal elements of the above-described sputtering target. For example, when a sputtering target whose atomic ratio of In, Ga, and Zn is 4:2:4.1 is used as the sputtering target for the oxide semiconductor films 108 and 128, the atomic ratio of In, Ga, and Zn in the oxide semiconductor films 108 and 128 is sometimes 4:2:3 or in the vicinity of 4:2:3.

[0212] The energy gap of the oxide semiconductor films 108 and 128 is 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. By using such an oxide semiconductor film with a wide energy gap, the off-state current of the transistors Tr1 and Tr2 can be reduced.

[0213] The thickness of the oxide semiconductor films 108 and 128 is greater than or equal to 3 nm and less than or equal to 200 nm, preferably greater than or equal to 3 nm and less than or equal to 100 nm, and more preferably greater than or equal to 3 nm and less than or equal to 50 nm.

[0214] Hydrogen contained in the oxide semiconductor films 108 and 128 reacts with oxygen bonded to a metal atom to generate water, and at the same time, oxygen vacancies are formed in a lattice where oxygen is detached (or a portion where oxygen is detached). When hydrogen enters the oxygen vacancies, electrons serving as carriers are sometimes generated. In addition, part of the hydrogen is sometimes bonded to oxygen bonded to a metal atom, and electrons serving as carriers are generated. Thus, a transistor including an oxide semiconductor film containing hydrogen tends to have a normally-on characteristic. Thus, it is preferable to reduce hydrogen in the oxide semiconductor films 108 and 128 as much as possible.

[0215] Specifically, in the oxide semiconductor films 108 and 128, the hydrogen concentration measured by SIMS is 2 x 10 20 atoms / cm 3 In the following, it is preferable that the hydrogen concentration be 5 x 10 19 atoms / cm 3 In the following, it is more preferable that the hydrogen concentration be 1 x 10 19 atoms / cm 3 In the following, it is more preferable that the hydrogen concentration be 5 x 10 18 atoms / cm 3 In the following, it is more preferable that the hydrogen concentration be 1 x 10 18 atoms / cm 3 In the following, it is more preferable that the hydrogen concentration be 5 x 10 17 atoms / cm 3 In the following, it is further preferable that the hydrogen concentration be 1 x 10 16 atoms / cm 3 or less.

[0216] When the oxide semiconductor films 108 and 128 contain silicon or carbon, which is one of Group 14 elements, oxygen vacancies are increased in the oxide semiconductor films 108 and 128, so that the oxide semiconductor films 108 and 128 become n-type films. Thus, the silicon concentration measured by SIMS in the oxide semiconductor films 108 and 128 is 2 x 10 18 atoms / cm 3 In the following, it is preferable that the silicon concentration be 2 x 10 17 atoms / cm 3The carbon concentration of the oxide semiconductor films 108 and 128 measured by SIMS analysis is 2 x 10 18 atoms / cm 3 The carbon concentration of the oxide semiconductor films 108 and 128 measured by SIMS analysis is 2 x 10 17 atoms / cm 3 The carbon concentration of the oxide semiconductor films 108 and 128 measured by SIMS analysis is 2 x 10 18 atoms / cm 3 The carbon concentration of the oxide semiconductor films 108 and 128 measured by SIMS analysis is 2 x 10 16 atoms / cm 3 The carbon concentration of the oxide semiconductor films 108 and 128 measured by SIMS analysis is 2 x 10

[0217] The alkali metal or alkaline earth metal concentration of the oxide semiconductor films 108 and 128 measured by SIMS analysis is 1 x 10 18 atoms / cm 3 The carbon concentration of the oxide semiconductor films 108 and 128 measured by SIMS analysis is 2 x 10 16 atoms / cm 3 The carbon concentration of the oxide semiconductor films 108 and 128 measured by SIMS analysis is 2 x 10

[0218] The oxide semiconductor films 108 and 128 can have a non-single-crystal structure, for example. Examples of the non-single-crystal structure include a CAAC-OS (c-axis-aligned crystalline oxide semiconductor), a polycrystalline structure, a microcrystalline structure, and an amorphous structure. In the non-single-crystal structure, the amorphous structure has the highest density of defect states, whereas the CAAC-OS has the lowest density of defect states.

[0219] The various films such as the conductive film, the insulating film, and the oxide semiconductor film described above can be formed by a sputtering method, a plasma enhanced chemical vapor deposition (PECVD) method, or a thermal CVD method. As an example of the thermal CVD method, a metal organic chemical vapor deposition (MOCVD) method or an atomic layer deposition (ALD) method can be given.

[0220] The thermal CVD method is a film formation method which does not use plasma, and thus has an advantage that defects caused by plasma damage are not generated.

[0221] The film formation by the thermal CVD method can be performed in such a manner that source gas and an oxidizer are simultaneously supplied into a processing chamber, the pressure in the processing chamber is set to be atmospheric pressure or reduced pressure, and a reaction is caused in the vicinity of a substrate or on the substrate.

[0222] Alternatively, the film formation by the ALD method can be performed with the pressure in the treatment chamber set to be equal to or lower than the atmospheric pressure, and the source gas for the reaction used.

[0223] Various films such as the conductive film, the insulating film, and the oxide semiconductor film described in this embodiment can be formed by a thermal CVD method such as an MOCVD method or an ALD method. For example, an In-Ga-Zn-O film can be formed using trimethyl indium, trimethyl gallium, and dimethyl zinc. The chemical formula of trimethyl indium is In(CH3)3. The chemical formula of trimethyl gallium is Ga(CH3)3. Further, the chemical formula of dimethyl zinc is Zn(CH3)2. Instead of trimethyl gallium, triethyl gallium (chemical formula: Ga(C2H5)3) can be used, and instead of dimethyl zinc, diethyl zinc (chemical formula: Zn(C2H5)2) can be used, without being limited to the above combination.

[0224] For example, in the case of forming a hafnium oxide film by using a film formation apparatus of the ALD method, two kinds of gases are used: ozone (O3) which is used as an oxidizing agent; and a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide, hafnium tetra-dimethylamide (TDMAH), or the like). Further, the chemical formula of hafnium tetra-dimethylamide is Hf[N(CH3)2]4. As another example of a material liquid, there is hafnium tetra(ethylmethylamide).

[0225] For example, in the case of forming an aluminum oxide film by using a film formation apparatus of the ALD method, two kinds of gases are used: H2O which is used as an oxidizing agent; and a source gas obtained by vaporizing a liquid containing a solvent and an aluminum precursor compound (e.g., trimethylaluminum (TMA)). Further, the chemical formula of trimethylaluminum is Al(CH3)3. As another example of a material liquid, there are aluminum tris(dimethylamide), aluminum triisobutyl, and aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedione).

[0226] For example, in the case of forming a silicon oxide film by using a film formation apparatus of the ALD method, hexachlorodisilane is attached to a film formation surface, chlorine contained in the attached material is removed, and radicals of an oxidizing gas (e.g., O2, dinitrogen monoxide) are supplied to react with the attached material.

[0227] For example, in the case of forming a tungsten film by using a film formation apparatus of the ALD method, a WF6gas and a B2H6gas are used to form an initial tungsten film, and then a WF6gas and an H2gas are used to form a tungsten film. Note that a SiH4gas can be used instead of the B2H6gas.

[0228] For example, in the case of forming an oxide semiconductor film such as an In-Ga-ZnO film using a deposition apparatus employing an ALD method, an In-O layer is formed by sequentially introducing In(CH3)3gas and O3gas, and then a GaO layer is formed using Ga(CH3)3gas and O3gas, and after that, a ZnO layer is formed using Zn(CH3)2gas and O3gas. Note that the order of these layers is not limited to the above example. Further, a mixed compound layer such as an In-Ga-O layer, an In-Zn-O layer, a Ga-Zn-O layer, or the like can be formed by mixing these gases. Instead of O3gas, H2O gas obtained by bubbling an inert gas such as Ar can be used, but O3gas which does not contain H is preferably used. Alternatively, In(C2H5)3gas can be used instead of In(CH3)3gas. Further, Ga(C2H5)3gas can be used instead of Ga(CH3)3gas. Alternatively, Zn(CH3)2gas can be used.

[0229] <1-6. Structure Example 2 of Semiconductor Device>

[0230] Next, a modification example of the semiconductor device 100 shown in FIGS. 1A and IB will be described with reference to FIGS. 2A and 2B. Figure 4A and Figure 4B and Figure 5 Figure 1A and Figure 1B

[0231] Figure 4A is a cross-sectional view of a modification example of the semiconductor device 100 shown in FIG. 1A. Figure 1B is a cross-sectional view of a modification example of the semiconductor device 100 shown in FIG. 1A. Figure 4B is a cross-sectional view of a modification example of the semiconductor device 100 shown in FIG. 1A. Figure 1B is a cross-sectional view of a modification example of the semiconductor device 100 shown in FIG. 1A. Figure 5 is a cross-sectional view of a modification example of the semiconductor device 100 shown in FIG. 1A. Figure 1B

[0232] Figure 4A

[0233] Figure 4B Figure 4B is a cross-sectional view of a modification example of the semiconductor device 100 shown in FIG. 1A.

[0234] ​​​​​ Figure 5 The diagram shows a structure without the conductive film 122c used as the second gate electrode of transistor Tr1 included in the semiconductor device 100, the conductive film 130 used as the second gate electrode of transistor Tr2, and the insulating film 134 on the conductive film 130 included in the semiconductor device 100. Furthermore, with... Figure 4B Similarly, openings 183 are formed in insulating films 124, 126 and 136.

[0235] <1-7. Structural Examples of Semiconductor Devices 3>

[0236] Below, refer to Figure 6A and Figure 6B and Figure 7A and Figure 7B right Figure 1A and Figure 1B A modified example of the semiconductor device 100 shown will be described.

[0237] The stacked structure of oxide semiconductor films will be described below.

[0238] Figure 6A and Figure 6B It is a cross-sectional view of the transistor Tr1 included in the semiconductor device 100 along the channel length (L) direction.

[0239] Figure 6A The oxide semiconductor film 108 of transistor Tr1 is shown to include an oxide semiconductor film 108a, an oxide semiconductor film 108b on the oxide semiconductor film 108a, and an oxide semiconductor film 108c on the oxide semiconductor film 108b. In other words, the oxide semiconductor film 108 has a three-layer structure.

[0240] Figure 6B The structure shown is that the oxide semiconductor film 108 of transistor Tr1 includes an oxide semiconductor film 108b and an oxide semiconductor film 108c on the oxide semiconductor film 108b. In other words, the oxide semiconductor film has a two-layer structure.

[0241] Figure 7A and Figure 7B An example of the band structure of the oxide semiconductor film 108 and the insulating film in contact with the oxide semiconductor film 108 is shown.

[0242] Figure 7A An example of an energy band diagram along the film thickness direction of a stacked body is shown, the stacked body having an insulating film 106, oxide semiconductor films 108a, 108b, 108c and an insulating film 114. Figure 7BAn example of a band diagram in the film thickness direction of a stack body having the insulating film 106, the oxide semiconductor films 108b and 108c, and the insulating film 114 is shown. In the band diagram, the energy levels (Ec) of the conduction band minimum of the insulating film 106, the oxide semiconductor films 108a, 108b, 108c, and the insulating film 114 are shown for easy understanding.

[0243] Figure 7A The band diagram is as follows: the insulating films 106 and 114 are silicon oxide films, the oxide semiconductor film 108a is an oxide semiconductor film formed using a metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 1:3:2, the oxide semiconductor film 108b is an oxide semiconductor film formed using a metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 4:2:4.1, and the oxide semiconductor film 108c is an oxide semiconductor film formed using a metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 1:3:2.

[0244] Figure 7B The band diagram is as follows: the insulating films 106 and 114 are silicon oxide films, the oxide semiconductor film 108b is an oxide semiconductor film formed using a metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 4:2:4.1, and the oxide semiconductor film 108c is an oxide semiconductor film formed using a metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 1:3:2.

[0245] As shown in FIGS. 17A and 17B, the energy level of the conduction band minimum changes gently between the oxide semiconductor film 108a and the oxide semiconductor film 108b and between the oxide semiconductor film 108b and the oxide semiconductor film 108c. In other words, the energy level of the conduction band minimum changes continuously or is continuously joined. In order to achieve such a band structure, no impurity that forms a trap center or a recombination center or the like is present at the interface between the oxide semiconductor film 108a and the oxide semiconductor film 108b or at the interface between the oxide semiconductor film 108b and the oxide semiconductor film 108c. Figure 7A Figure 7B As shown in FIGS. 17A and 17B, the energy level of the conduction band minimum changes gently between the oxide semiconductor film 108a and the oxide semiconductor film 108b and between the oxide semiconductor film 108b and the oxide semiconductor film 108c. In other words, the energy level of the conduction band minimum changes continuously or is continuously joined. In order to achieve such a band structure, no impurity that forms a trap center or a recombination center or the like is present at the interface between the oxide semiconductor film 108a and the oxide semiconductor film 108b or at the interface between the oxide semiconductor film 108b and the oxide semiconductor film 108c.

[0246] In order to form a continuously joined structure between the oxide semiconductor film 108a and the oxide semiconductor film 108b and between the oxide semiconductor film 108b and the oxide semiconductor film 108c, a multi-chamber deposition apparatus (sputtering apparatus) provided with a load lock chamber is used to continuously stack the films without exposure to the atmosphere.

[0247] By employing Figure 7A and Figure 7B ​The band structure of the oxide semiconductor film 108b is such that the oxide semiconductor film 108b becomes a well, and in a transistor using the above-described stacked structure, a channel region is formed in the oxide semiconductor film 108b.

[0248] By providing the oxide semiconductor film 108a and / or the oxide semiconductor film 108c, the oxide semiconductor film 108b can be distanced from the trap level.

[0249] Further, sometimes the trap level is farther from the vacuum level than the conduction band bottom level (Ec) of the oxide semiconductor film 108b used as a channel region, and electrons are easily accumulated in the trap level. When electrons are accumulated in the trap level, the electrons become negative fixed charges, which causes the threshold voltage of the transistor to drift in the positive direction. Thus, it is preferable that the trap level be closer to the vacuum level than the conduction band bottom level (Ec) of the oxide semiconductor film 108b. With the above structure, accumulation of electrons in the trap level can be suppressed. As a result, the on-state current and the field-effect mobility of the transistor can be increased.

[0250] The conduction band bottom level of the oxide semiconductor films 108a and 108c is closer to the vacuum level than that of the oxide semiconductor film 108b. Typically, the difference between the conduction band bottom level of the oxide semiconductor film 108b and the conduction band bottom level of the oxide semiconductor films 108a and 108c is greater than or equal to 0.15 eV or greater than or equal to 0.5 eV, and is less than or equal to 2 eV or less than or equal to 1 eV. In other words, the difference between the electron affinity of the oxide semiconductor films 108a and 108c and the electron affinity of the oxide semiconductor film 108b is greater than or equal to 0.15 eV or greater than or equal to 0.5 eV, and is less than or equal to 2 eV or less than or equal to 1 eV.

[0251] With the above structure, the oxide semiconductor film 108b becomes a main path of current and is used as a channel region. Further, since the oxide semiconductor films 108a and 108c include one or more of the metal elements included in the oxide semiconductor film 108b which forms a channel region, interface scattering is not easily generated at the interface between the oxide semiconductor film 108a and the oxide semiconductor film 108b or at the interface between the oxide semiconductor film 108b and the oxide semiconductor film 108c. Thus, since movement of carriers is not hindered in the interface, the field-effect mobility of the transistor is increased.

[0252] In order to prevent the oxide semiconductor films 108a and 108c from being used as part of a channel region, a material with low conductivity is used as the oxide semiconductor films 108a and 108c. Alternatively, a material whose electron affinity (difference between the vacuum level and the conduction band minimum) is lower than that of the oxide semiconductor film 108b and whose conduction band minimum is different from (band offset from) the conduction band minimum of the oxide semiconductor film 108b is used as the oxide semiconductor films 108a and 108c. Further, in order to suppress a difference between threshold voltages due to a drain voltage value, the oxide semiconductor films 108a and 108c are preferably formed of a material whose conduction band minimum is closer to the vacuum level than the conduction band minimum of the oxide semiconductor film 108b. For example, the difference between the conduction band minimum of the oxide semiconductor film 108b and the conduction band minimum of the oxide semiconductor films 108a and 108c is preferably 0.2 eV or more, further preferably 0.5 eV or more.

[0253] The oxide semiconductor films 108a and 108c preferably do not include a spinel crystal structure. This is because if the oxide semiconductor films 108a and 108c include a spinel crystal structure, the constituent elements of the conductive films 112a and 112b sometimes diffuse into the oxide semiconductor film 108b at the interface between the spinel crystal structure and another region. Note that the oxide semiconductor films 108a and 108c are preferably CAAC-OS described later, in which case high barrier properties against the constituent elements of the conductive films 112a and 112b, such as copper elements, can be obtained.

[0254] The thickness of the oxide semiconductor films 108a and 108c is greater than or equal to a thickness at which diffusion of the constituent elements of the conductive films 112a and 112b into the oxide semiconductor film 108b is inhibited and smaller than a thickness at which supply of oxygen from the insulating film 114 to the oxide semiconductor film 108b is inhibited. For example, when the thickness of the oxide semiconductor films 108a and 108c is 10 nm or more, diffusion of the constituent elements of the conductive films 112a and 112b into the oxide semiconductor film 108b can be inhibited. When the thickness of the oxide semiconductor films 108a and 108c is 100 nm or less, oxygen can be efficiently supplied from the insulating film 114 to the oxide semiconductor film 108b.

[0255] When the oxide semiconductor films 108a and 108c are In-M-Zn oxide (M is Al, Ga, Y, or Sn) in which the atomic ratio of M is higher than that of In, the energy gap of the oxide semiconductor films 108a and 108c can be made larger and the electron affinity thereof can be made smaller. Thus, the difference in electron affinity between the oxide semiconductor films 108a and 108c and the oxide semiconductor film 108b can be controlled depending on the proportion of the element M. Further, since M is a metal element with strong bonding force to oxygen, oxygen defects are less likely to be generated in the oxide semiconductor layer in which the atomic ratio of the element M is higher than that of In.

[0256] When an In-M-Zn oxide is used for the oxide semiconductor films 108a, 108c, the ratio of In and M, excluding Zn and O, is preferably lower than 50 atomic% for In and higher than 50 atomic% for M, and is more preferably lower than 25 atomic% for In and higher than 75 atomic% for M. Note that a gallium oxide film can be used as the oxide semiconductor films 108a, 108c.

[0257] In addition, when the oxide semiconductor films 108a, 108b, 108c are In-M-Zn oxides, the atomic ratio of M in the oxide semiconductor films 108a, 108c is higher than that in the oxide semiconductor film 108b. Typically, the atomic ratio of M in the oxide semiconductor films 108a, 108c is 1.5 times or more, preferably 2 times or more, and more preferably 3 times or more, as high as that in the oxide semiconductor film 108b.

[0258] In addition, when the oxide semiconductor films 108a, 108b, 108c are In-M-Zn oxides, in the case where the atomic ratio of the oxide semiconductor film 108b is In:M:Zn = x1:y1:z1 and the atomic ratio of the oxide semiconductor films 108a, 108c is In:M:Zn = x2:y2:z2, y2 / x2 is higher than y1 / x1, y2 / x2 is preferably 1.5 times or more as high as y1 / x1, y2 / x2 is more preferably 2 times or more as high as y1 / x1, and y2 / x2 is further preferably 3 times or more or 4 times or more as high as y1 / x1. At this time, y1 is preferably higher than or equal to x1, and at this time, the transistor including the oxide semiconductor film 108b can have stable electrical characteristics. However, in the case where y1 is higher than or equal to 3 times x1, the field-effect mobility of the transistor including the oxide semiconductor film 108b is decreased. Thus, y1 is preferably lower than 3 times x1.

[0259] In the case where the oxide semiconductor film 108b is an In-M-Zn oxide and the atomic ratio of the metal elements of a target used for forming the oxide semiconductor film 108b is In:M:Zn = x1:y1:z1, x1 / y1 is preferably greater than or equal to 1 / 3 and less than or equal to 6, more preferably greater than or equal to 1 and less than or equal to 6. Note that when z1 / y1 is greater than or equal to 1 and less than or equal to 6, the CAAC-OS described later is easily formed as the oxide semiconductor film 108b. Typical examples of the atomic ratio of the metal elements of a target include In:M:Zn = 4:2:4.1, In:M:Zn = 1:1:1.2, and In:M:Zn = 3:1:2.

[0260] In the case where the oxide semiconductor films 108a and 108c are In-M-Zn oxides and the atomic ratio of the metal elements of a target used for forming the oxide semiconductor films 108a and 108c is In:M:Zn = x2:y2:z2, x2 / y2 < x1 / y1 and z2 / y2 is preferably greater than or equal to 1 / 3 and less than or equal to 6, more preferably greater than or equal to 1 and less than or equal to 6. When the atomic ratio of M is higher than that of In, the energy gap of the oxide semiconductor films 108a and 108c can be increased and the electron affinity thereof can be decreased, and thus y2 / x2 is preferably greater than or equal to 3 or greater than or equal to 4. Typical examples of the atomic ratio of the metal elements of a target include In:M:Zn = 1:3:2, In:M:Zn = 1:3:4, In:M:Zn = 1:3:5, In:M:Zn = 1:3:6, In:M:Zn = 1:4:2, In:M:Zn = 1:4:4, In:M:Zn = 1:4:5, and In:M:Zn = 1:5:5.

[0261] In the case where the oxide semiconductor films 108a and 108c are In-M oxides, when M does not include a divalent metal atom (e.g., zinc), an oxide semiconductor film 108a and 108c which does not have a spinel crystal structure can be formed. As the oxide semiconductor film 108a and 108c, an In-Ga oxide film can be used, for example. This In-Ga oxide film can be formed by a sputtering method using an In-Ga metal oxide target (In:Ga = 7:93), for example. In order to form the oxide semiconductor film 108a and 108c by a sputtering method using DC discharge, when the atomic ratio of In:M is assumed to be x:y, y / (x+y) is preferably less than or equal to 0.96, more preferably less than or equal to 0.95, and for example, is 0.93.

[0262] In the oxide semiconductor films 108a, 108b, and 108c, the atomic ratio in the above atomic ratio is varied by ±40 % as an error.

[0263] In Figure 6A and Figure 6B the oxide semiconductor film 108 of the transistor Tr1 has a two-layer structure or a three-layer structure, the oxide semiconductor film 128 of the transistor Tr2 can have the same structure.

[0264] As described above, in the semiconductor device of the present application, the presence or absence of the second gate electrode can be changed, or the stacked structure of the oxide semiconductor film can be changed. The structures of the transistors of this embodiment can be freely combined with each other.

[0265] <1-8. Method for manufacturing semiconductor device>

[0266] Next, a method for manufacturing the semiconductor device 100 of one embodiment of the present application will be described with reference to Figure 8A and Figures 8B to 17A and Figure 17B

[0267] Further, Figure 8A , Figure 9A , Figure 10A , Figure 11A , Figure 12A , Figure 13A , Figure 14A , Figure 15A , Figure 16A and Figure 17A are cross-sectional views illustrating the method for manufacturing the semiconductor device 100. Figure 8B , Figure 9B , Figure 10B , Figure 11B , Figure 12B , Figure 13B , Figure 14B , Figure 15B , Figure 16B and Figure 17B are cross-sectional views illustrating the method for manufacturing the semiconductor device 100.

[0268] First, a conductive film is formed over the substrate 102, and the conductive film is processed by a photolithography process and an etching process to form the conductive film 104 which is used as the first gate electrode. Then, the insulating film 106 which is used as the first gate insulating film is formed over the conductive film 104 (see Figure 8A and Figure 8B ).

[0269] In this embodiment, a glass substrate is used as the substrate 102, and a tungsten film with a thickness of 100 nm is formed by a sputtering method as the conductive film 104 which is used as the first gate electrode. A silicon nitride film with a thickness of 400 nm and a silicon oxynitride film with a thickness of 50 nm are formed by a PECVD method as the insulating film 106.

[0270] ​Further, the insulating film 106 can have a stacked structure of silicon nitride films. Specifically, the silicon nitride film can have a three-layer structure of a first silicon nitride film, a second silicon nitride film, and a third silicon nitride film. Examples of the three-layer structure are as follows.

[0271] For example, the first silicon nitride film with a thickness of 50 nm can be formed under conditions where silane with a flow rate of 200 sccm, nitrogen with a flow rate of 2000 sccm, and ammonia gas with a flow rate of 100 sccm are supplied to a reaction chamber of a PECVD apparatus as source gases, the pressure in the reaction chamber is controlled to be 100 Pa, and a power of 2000 W is supplied using a high-frequency power supply of 27.12 MHz.

[0272] The second silicon nitride film with a thickness of 300 nm can be formed under conditions where silane with a flow rate of 200 sccm, nitrogen with a flow rate of 2000 sccm, and ammonia gas with a flow rate of 2000 sccm are supplied to a reaction chamber of a PECVD apparatus as source gases, the pressure in the reaction chamber is controlled to be 100 Pa, and a power of 2000 W is supplied using a high-frequency power supply of 27.12 MHz.

[0273] The third silicon nitride film with a thickness of 50 nm can be formed under conditions where silane with a flow rate of 200 sccm and nitrogen with a flow rate of 5000 sccm are supplied to a reaction chamber of a PECVD apparatus as source gases, the pressure in the reaction chamber is controlled to be 100 Pa, and a power of 2000 W is supplied using a high-frequency power supply of 27.12 MHz.

[0274] Further, the first silicon nitride film, the second silicon nitride film, and the third silicon nitride film can be formed at a substrate temperature of 350 °C or lower.

[0275] When the insulating film 106 has the three-layer structure of silicon nitride films, the following effects can be obtained, for example, in the case where a conductive film containing copper (Cu) is used as the conductive film 104.

[0276] The first silicon nitride film can suppress diffusion of copper (Cu) from the conductive film 104. The second silicon nitride film has a function of releasing hydrogen and can increase the withstand voltage of the insulating film used as a gate insulating film. The third silicon nitride film is a film with a small amount of released hydrogen and can suppress diffusion of hydrogen released from the second silicon nitride film.

[0277] Next, an oxide semiconductor film 108 is formed over the insulating film 106 (see Figure 9A and Figure 9B ).

[0278] In this embodiment, an oxide semiconductor film is formed by a sputtering method using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). The substrate temperature at the time of formation of the oxide semiconductor film is 170 °C. As a deposition gas at the time of formation of the oxide semiconductor film, an oxygen gas with a flow rate of 60 seem and an argon gas with a flow rate of 140 seem are used. Then, the oxide semiconductor film is processed into a desired shape, whereby an island-shaped oxide semiconductor film 108 is formed. Note that a wet etching apparatus is used at the time of formation of the oxide semiconductor film.

[0279] Next, a conductive film is formed over the insulating film 106 and the oxide semiconductor film 108, and is processed into a desired shape, whereby a conductive film 112a and a conductive film 112b are formed. Then, an insulating film 114 and an insulating film 116 are formed over the insulating film 106, the oxide semiconductor film 108, and the conductive films 112a and 112b (see FIG. 1C). Figure 10A and Figure 10B ).

[0280] In this embodiment, as the conductive films 112a and 112b, a stacked film in which an aluminum film with a thickness of 100 nm and a titanium film with a thickness of 50 nm are sequentially stacked is formed by a sputtering method.

[0281] After the formation of the conductive films 112a and 112b, the surface (back channel side) of the oxide semiconductor film 108 can be washed. The washing can be performed with an etchant such as a phosphoric acid aqueous solution. By the washing, impurities (e.g., elements included in the conductive films 112a and 112b) attached to the surface of the oxide semiconductor film 108 can be removed. Note that the washing is not necessarily performed, and can be omitted in some cases.

[0282] In the formation of the conductive films 112a and 112b and / or the above washing process, the thickness of the region of the oxide semiconductor film 108 which is not covered with the conductive films 112a and 112b is sometimes thinned.

[0283] In this embodiment, a silicon oxynitride film with a thickness of 20 nm and a silicon oxynitride film with a thickness of 200 nm are formed as the insulating film 114 and the insulating film 116, respectively, by a PECVD method.

[0284] It is preferable that the insulating film 116 be formed continuously without exposure to the atmosphere after the insulating film 114 is formed. The insulating film 116 is formed continuously without exposure to the atmosphere after the insulating film 114 is formed, with at least one of the flow rate of the source gas, the pressure, the high-frequency power, and the substrate temperature adjusted, whereby the concentration of impurities derived from the atmospheric components at the interface of the insulating film 114 and the insulating film 116 can be reduced, and oxygen in the insulating films 114 and 116 can be moved into the oxide semiconductor film 108, so that the amount of oxygen vacancies in the oxide semiconductor film 108 can be reduced.

[0285] In this embodiment, as the insulating film 114, a silicon oxynitride film is formed by a PECVD method under conditions where the temperature of the substrate 102 is kept at 220 °C, silane with a flow rate of 50 sccm and dinitrogen monoxide with a flow rate of 2000 sccm are used as source gases, the pressure in the treatment chamber is 20 Pa, and a high-frequency power of 100 W (power density: 1.6 x 10 -2 W / cm 2 ) is supplied to the parallel plate electrodes at a frequency of 13.56 MHz.

[0286] As the insulating film 116, a silicon oxide film or a silicon oxynitride film is formed under conditions where the temperature of a substrate provided in a treatment chamber of a PECVD device which is vacuum-pumped is kept at 180 °C to 350 °C, a source gas is introduced into the treatment chamber, the pressure in the treatment chamber is set to 100 Pa to 250 Pa, preferably 100 Pa to 200 Pa, and a high-frequency power of 0.17 W / cm 2 or more and 0.5 W / cm 2 or less, preferably 0.25 W / cm 2 or more and 0.35 W / cm 2 or less is supplied to an electrode provided in the treatment chamber.

[0287] In the film formation conditions of the insulating film 116, a high-frequency power with the above-described power density is supplied to a reaction chamber having the above-described pressure, whereby the decomposition efficiency of the source gas in plasma is increased, the oxygen radicals are increased, and oxidation of the source gas is promoted, and thus the oxygen content in the insulating film 116 exceeds the stoichiometric composition. In a film formed at a substrate temperature in the above-described temperature range, the bonding force between silicon and oxygen is weak, and thus a part of the oxygen in the film is released by heat treatment in a later step. Thus, an oxide insulating film whose oxygen content exceeds the stoichiometric composition and which releases a part of the oxygen by heat can be formed.

[0288] In addition, in the formation of the insulating film 116, the insulating film 114 is used as a protective film for the oxide semiconductor film 108. Thus, the insulating film 116 can be formed using high-frequency power with high power density while reducing damage to the oxide semiconductor film 108.

[0289] In addition, in the film formation conditions of the insulating film 116, the amount of defects in the insulating film 116 can be reduced by increasing the flow rate of the deposition gas containing silicon with respect to the oxidizing gas. Typically, an oxide insulating film with a low amount of defects can be formed, in which the spin density of a signal attributed to a silicon dangling bond and appearing at g = 2.001 measured by ESR is lower than 6 x 10 17 spins / cm 3 , preferably 3 x 10 17 spins / cm 3 , more preferably 1.5 x 10 17 spins / cm 3 or lower. As a result, the reliability of the transistor Tr1 can be improved.

[0290] It is preferable to perform a heat treatment (hereinafter referred to as a first heat treatment) after the formation of the insulating films 114 and 116. By the first heat treatment, the nitride oxide contained in the insulating films 114 and 116 can be reduced. By the first heat treatment, a part of oxygen contained in the insulating films 114 and 116 can be moved to the oxide semiconductor film 108, so that the amount of oxygen vacancies in the oxide semiconductor film 108 can be reduced.

[0291] The temperature of the first heat treatment is typically lower than 400 °C, preferably lower than 375 °C, further preferably higher than or equal to 150 °C and lower than or equal to 350 °C. The first heat treatment can be performed in an atmosphere of nitrogen, oxygen, ultra-dry air (air whose water content is 20 ppm or lower, preferably 1 ppm or lower, preferably 10 ppb or lower), or a rare gas (e.g., argon, helium). Further, it is preferable that hydrogen, water, or the like be not contained in the above-described nitrogen, oxygen, ultra-dry air, or rare gas. An electric furnace, an RTA (rapid thermal anneal) apparatus, or the like can be used for the heat treatment.

[0292] Next, an oxide semiconductor film 128 is formed over the insulating film 116 (see Figure 11A and Figure 11B ).

[0293] In this embodiment, an oxide semiconductor film is formed by a sputtering method using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic percentage ratio]). The substrate temperature at the time of formation of the oxide semiconductor film is 170 °C. As a deposition gas at the time of formation of the oxide semiconductor film, an oxygen gas with a flow rate of 60 seem and an argon gas with a flow rate of 140 seem are used. Then, the oxide semiconductor film is processed into a desired shape, whereby an island-shaped oxide semiconductor film 128 is formed. Note that a wet etching apparatus is used at the time of formation of the oxide semiconductor film.

[0294] Next, a conductive film 122a, 122b, 122c is formed over the insulating film 116 and the oxide semiconductor film 128, and then an insulating film 124, 126 is formed over the insulating film 116, the oxide semiconductor film 128, and the conductive film 122a, 122b, 122c (see Figure 12A and Figure 12B ).

[0295] The conductive film 122a, 122b, 122c can be formed by the same method as the conductive film 112a, 112b described above. The insulating film 124, 126 can be formed by the same method as the insulating film 114, 116 described above.

[0296] Next, an opening 182 reaching the conductive film 122a is formed in a desired region of the insulating film 124, 126. Then, a conductive film 130 is formed over the insulating film 126 and the conductive film 122a (see Figure 13A and Figure 13B ).

[0297] At the time of formation of the opening 182, a dry etching apparatus or a wet etching apparatus can be used. An ITSO film (In203:Sn02:Si02= 85:10:5 [wt%]) with a thickness of 100 nm is formed using an oxide target containing indium, tin, and silicon (also referred to as ITSO), and is processed into an island shape, whereby the conductive film 130 is obtained.

[0298] Next, a stack film of an insulating film which becomes an insulating film 134 and 136 is formed over the insulating film 126 and the conductive film 130. Then, an opening 184 reaching the conductive film 130 is formed in a desired region of the stack film (see Figure 14A and Figure 14B ).

[0299] As the insulating film 134, a silicon oxynitride film with a thickness of 200 nm is formed by a PECVD method. As the insulating film 136, a photosensitive acrylic resin organic resin film with a thickness of 1.5 μιη is formed.

[0300] When forming the opening 184, a dry etching apparatus or a wet etching apparatus is used.

[0301] Next, a conductive film is formed over the insulating film 136 and the conductive film 130, and is processed into an island shape, whereby a conductive film 138 is formed (see Figure 15A and Figure 15B ).

[0302] As the conductive film 138 in this embodiment, a laminated film of an ITO film with a thickness of 10 nm, a reflective metal film (in this case, a metal film containing silver, palladium, and copper) with a thickness of 200 nm, and an ITO film with a thickness of 10 nm is used. This laminated film is processed into the conductive film 138 using a wet etching apparatus.

[0303] Next, an island-shaped insulating film 140 is formed over the insulating film 136 and the conductive film 138 (see Figure 16A and Figure 16B ).

[0304] As the insulating film 140, a photosensitive polyimide-based organic resin film with a thickness of 1.5 μm is used.

[0305] Next, an EL layer 142 is formed over the conductive film 138, and then a conductive film 144 is formed over the insulating film 140 and the EL layer 142, whereby a light-emitting element 160 is obtained (see Figure 17A and Figure 17B ).

[0306] Note that the manufacturing method of the light-emitting element 160 will be described in detail in Embodiment 3.

[0307] By the above manufacturing process, the semiconductor device 100 illustrated in Figure 1A and Figure 1B can be manufactured.

[0308] The structure and method described in this embodiment can be combined with the structures and methods described in other embodiments as appropriate.

[0309] Embodiment 2

[0310] In this embodiment, a semiconductor device and a manufacturing method of a semiconductor device according to one embodiment of the present application will be described with reference to Figure 18A and Figures 18B to 29A and Figure 29B

[0311] <2-1. Structure Example 1 of Semiconductor Device>

[0312] Figure 18A is a top view of a semiconductor device 200 according to one embodiment of the present application. Figure 18B is a cross-sectional view taken along Figure 18A ​a cross-sectional view of the point-and-line A1-A2 in FIG. 1. Furthermore, Figure 18B a cross section in a channel length (L) direction of the transistor Trl and a cross section in a channel length (L) direction of the transistor Tr2.

[0313] Figure 18A and Figure 18B The semiconductor device 100 illustrated in FIG. 1 includes a transistor Trl and a transistor Tr2 overlapping at least a part of the transistor Trl. Furthermore, the transistor Trl is a bottom-gate transistor and the transistor Tr2 is a top-gate transistor.

[0314] Since the transistor Trl at least partially overlaps the transistor Tr2, the area of the transistor can be reduced.

[0315] The transistor Trl includes a conductive film 104 over a substrate 102, an insulating film 106 over the substrate 102 and the conductive film 104, an oxide semiconductor film 108 over the insulating film 106, a conductive film 112a over the oxide semiconductor film 108, a conductive film 112b over the oxide semiconductor film 108, an insulating film 114 over the oxide semiconductor film 108, the conductive film 112a, and the conductive film 112b, an insulating film 116 over the insulating film 114, an insulating film 118 over the insulating film 116, an insulating film 119 over the insulating film 118, an insulating film 210a over the insulating film 119, and a conductive film 212a over the insulating film 210a.

[0316] The transistor Tr2 includes a conductive film 112c, an insulating film 114 over the conductive film 112c, an insulating film 116 over the insulating film 114, an insulating film 118 over the insulating film 116, an insulating film 119 over the insulating film 118, an oxide semiconductor film 208 over the insulating film 119, an insulating film 210b over the oxide semiconductor film 208, a conductive film 212b over the insulating film 210b, an insulating film 214 over the oxide semiconductor film 208 and the conductive film 212b, an insulating film 216 over the insulating film 214, a conductive film 218a over the insulating film 216 and electrically connected to the oxide semiconductor film 208, and a conductive film 218b over the insulating film 216 and electrically connected to the oxide semiconductor film 208.

[0317] Furthermore, as illustrated in FIG. 1, Figure 18A and Figure 18B The oxide semiconductor film 108 and the oxide semiconductor film 208 partially overlap with each other.

[0318] The oxide semiconductor film 108 can have the same structure as that of the structure illustrated in Embodiment 1. The oxide semiconductor film 208 can have the same structure as that of the oxide semiconductor film 128 illustrated in Embodiment 1.

[0319] Specifically, one or both of the field-effect mobilities of transistors Tr1 and Tr2 can exceed 10 cm⁻¹. 2 / Vs, preferably, exceeding 30cm 2 / Vs.

[0320] For example, when the aforementioned high field-effect mobility transistor is used in the gate driver of a display device to generate gate signals, the display device can have a narrow bezel. When the aforementioned high field-effect mobility transistor is used in the source driver (especially the demultiplexer connected to the output terminal of the shift register included in the source driver) of the display device to supply signals from signal lines, the number of wiring connections to the display device can be reduced. Furthermore, when the aforementioned high field-effect mobility transistor is used in one or both of the selection transistor and drive transistor of the pixel circuit included in the display device, the display quality of the display device can be improved.

[0321] Figure 18A and Figure 18B The semiconductor device 100 shown can be suitably used in the pixel circuit of a display device. Figure 18A and Figure 18B The layout shown can increase the pixel density of a display device. For example, even if the pixel density of the display device exceeds 1000ppi or 2000ppi, by... Figure 18A and Figure 18B The layout shown can also increase the pixel aperture ratio.

[0322] In addition, in the Figure 18A and Figure 18B When the semiconductor device 100 shown is used in the pixel circuit of a display device, it can be used with, for example... Figure 2 The pixel circuit shown has the same structure.

[0323] In FIG. 18A and FIG. 18B When the semiconductor device 100 shown is used for pixels in a display device, for example, the channel length (L) and channel width (W) of the transistor, as well as the line width of the wiring and electrodes connected to the transistor, can be larger. For example, when... FIG. 18A and FIG. 18B When transistors Tr1 and Tr2 are arranged in an overlapping manner as shown, the line width can be increased, etc., compared with the case where transistors Tr1 and Tr2 are arranged on the same plane, so the non-uniformity of the processing dimensions can be reduced.

[0324] Furthermore, one or both of the conductive and insulating films can be used together between transistors Tr1 and Tr2, thus reducing the number of masks or processes.

[0325] For example, in the transistor Trl, the conductive film 104 is used as a first gate electrode, the conductive film 112a is used as a source electrode, the conductive film 112b is used as a drain electrode, and the conductive film 212a is used as a second gate electrode. Further, in the transistor Trl, the insulating film 106 is used as a first gate insulating film, and the insulating films 114, 116, 118, 119, and 210a are used as second gate insulating films. In the transistor Tr2, the conductive film 112c is used as a first gate electrode, the conductive film 218a is used as a source electrode, the conductive film 218b is used as a drain electrode, and the conductive film 212b is used as a second gate electrode. Further, in the transistor Tr2, the insulating films 114, 116, 118, and 119 are used as first gate insulating films, and the insulating film 210b is used as a second gate insulating film.

[0326] Note that in this specification and the like, the insulating film 210a is sometimes referred to as a fourth insulating film, and the insulating film 210b is sometimes referred to as a fifth insulating film.

[0327] The insulating film 136 is provided over the insulating film 216 and the conductive films 218a and 218b. The opening 186 reaching the conductive film 218b is provided in the insulating film 136. Further, the conductive film 138 is provided over the insulating film 136. The conductive film 138 is connected to the conductive film 218b in the opening 186.

[0328] Further, the insulating film 140, the EL layer 142, and the conductive film 144 are provided over the conductive film 138. The light-emitting element 160 is formed of the conductive film 138, the EL layer 142, and the conductive film 144.

[0329] As described above, one embodiment of the present application can combine a bottom-gate transistor and a top-gate transistor.

[0330] Further, although not illustrated, the transistor Trl and the transistor Tr2 illustrated in FIG. 1A can have the S-channel structure described in Embodiment 1. FIG. 18A and FIG. 18B The transistor Trl and the transistor Tr2 illustrated in FIG. 1A can have the S-channel structure described in Embodiment 1.

[0331] The transistor Trl and the transistor Tr2 included in the semiconductor device 200 of this embodiment can be combined with the transistor Trl and the transistor Tr2 included in the semiconductor device 100 of Embodiment 1.

[0332] As described above, in the semiconductor device of one embodiment of the present application, a plurality of transistors are stacked, whereby the area of the transistors can be reduced. Further, since one or both of an insulating film and a conductive film are commonly used between the plurality of transistors, the number of masks or the number of steps can be reduced.

[0333] <2-2. Constituent elements of semiconductor device>

[0334] Next, the components of the semiconductor device according to this embodiment are described in detail.

[0335] [Conductive film]

[0336] The conductive films 212a, 212b, 218a, and 218b can be formed using the materials of the conductive films (the conductive film 104, the conductive film 112a, the conductive film 112b, the conductive film 122a, the conductive film 122b, the conductive film 122c, the conductive film 130, the conductive film 138, and the conductive film 144) described in Embodiment 1. In particular, as the conductive films 212a and 212b, an oxide conductor (OC) is preferably used because oxygen can be added to the insulating films 210a and 210b.

[0337] [Insulating film]

[0338] The insulating films 118, 119, 214, 216, 210a, and 210b can be formed using the materials of the insulating films (the insulating film 106, the insulating film 114, the insulating film 116, the insulating film 124, the insulating film 126, the insulating film 134, the insulating film 136, and the insulating film 140) described in Embodiment 1.

[0339] In particular, a silicon nitride film or a silicon oxynitride film is preferably used as the insulating film 118, in which case impurities can be prevented from being mixed into the transistor Tr1. Since the insulating film 119 is in contact with the oxide semiconductor film 208, an oxide insulating film is preferably used as the insulating film 119, and a silicon oxide film or a silicon oxynitride film is particularly preferably used as the insulating film 119. As the insulating films 210a and 210b, an oxide insulating film is preferably used. The insulating films 210a and 210b preferably have a region in which the oxygen content is higher than that in the stoichiometric composition (excess-oxygen region). As the insulating films 210a and 210b, a silicon oxide film or a silicon oxynitride film is preferably used.

[0340] The insulating film 214 contains one or both of hydrogen and nitrogen. Alternatively, the insulating film 214 contains nitrogen and silicon. The insulating film 214 has a function of blocking oxygen, hydrogen, water, alkali metal, alkaline earth metal, or the like. Since the oxide semiconductor film 208 is in contact with the insulating film 214, one or both of hydrogen and nitrogen in the insulating film 214 enters the oxide semiconductor film 208, whereby the carrier density of the oxide semiconductor film 208 is increased. Thus, a region of the oxide semiconductor film 208 which is in contact with the insulating film 214 serves as a source region or a drain region.

[0341] [Oxide semiconductor film]

[0342] The oxide semiconductor film 208 can be formed using the materials of the oxide semiconductor films (the oxide semiconductor film 108 and the oxide semiconductor film 128) described in Embodiment 1.

[0343] <2-3. Method for manufacturing semiconductor device>

[0344] Next, a method for manufacturing the semiconductor device 200 of one embodiment of the present application will be described with reference to cross-sectional views and plan views. FIG. 19A and FIG. 19B to FIG. 29A and FIG. 29B A method for manufacturing the semiconductor device 200 of one embodiment of the present application will be described.

[0345] Further, FIG. 19A , FIG. 20A , FIG. 21A , FIG. 22A , FIG. 23A , FIG. 24A , FIG. 25A , FIG. 26A , FIG. 27A , FIG. 28A and FIG. 29A are cross-sectional views illustrating the method for manufacturing the semiconductor device 200. FIG. 19B , FIG. 20B , FIG. 21B , FIG. 22B , FIG. 23B , FIG. 24B , FIG. 25B , FIG. 26B , FIG. 27B , FIG. 28B and FIG. 29B are cross-sectional views illustrating the method for manufacturing the semiconductor device 200.

[0346] First, a conductive film is formed over the substrate 102, and the conductive film is processed by a photolithography process and an etching process to form the conductive film 104 which is used as a first gate electrode. Then, the insulating film 106 which is used as a first gate insulating film is formed over the conductive film 104 (see FIG. 19A and FIG. 19B ).

[0347] In this embodiment mode, a glass substrate is used as the substrate 102, and a tungsten film with a thickness of 100 nm is formed by a sputtering method as the conductive film 104 which is used as a first gate electrode. A silicon nitride film with a thickness of 400 nm and a silicon oxynitride film with a thickness of 50 nm are formed by a PECVD method as the insulating film 106.

[0348] Next, the oxide semiconductor film 108 is formed over the insulating film 106 (see FIG. 20A and FIG. 20B ).

[0349] In this embodiment, an oxide semiconductor film is formed by a sputtering method using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic percentage ratio]). The substrate temperature at the time of formation of the oxide semiconductor film is 170 °C. As a deposition gas at the time of formation of the oxide semiconductor film, an oxygen gas with a flow rate of 60 seem and an argon gas with a flow rate of 140 seem are used. Then, the oxide semiconductor film is processed into a desired shape, whereby an island-shaped oxide semiconductor film 108 is formed. Note that a wet etching apparatus is used at the time of formation of the oxide semiconductor film.

[0350] Next, a conductive film is formed over the insulating film 106 and the oxide semiconductor film 108, and is processed into a desired shape, whereby conductive films 112a, 112b, and 112c are formed. Then, insulating films 114, 116, 118, and 119 are formed over the insulating film 106, the oxide semiconductor film 108, and the conductive films 112a, 112b, and 112c (see FIG. 21A and FIG. 21B ).

[0351] In this embodiment, as the conductive films 112a, 112b, and 112c, a stacked film in which an aluminum film with a thickness of 100 nm and a titanium film with a thickness of 50 nm are sequentially stacked is formed by a sputtering method.

[0352] In this embodiment, as the insulating film 114, the insulating film 116, the insulating film 118, and the insulating film 119, a silicon oxynitride film with a thickness of 20 nm, a silicon oxynitride film with a thickness of 200 nm, a silicon oxynitride film with a thickness of 100 nm, and a silicon oxynitride film with a thickness of 50 nm are formed by a PECVD method, respectively.

[0353] It is preferable that first heat treatment be performed after the formation of the insulating films 114, 116, 118, and 119. By the first heat treatment, part of oxygen included in the insulating films 114 and 116 can be moved to the oxide semiconductor film 108, and the amount of oxygen vacancies in the oxide semiconductor film 108 can be reduced.

[0354] Next, an oxide semiconductor film 208 is formed over the insulating film 119 (see FIG. 22A and FIG. 22B ).

[0355] In this embodiment, an oxide semiconductor film is formed by a sputtering method using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). The substrate temperature at the time of formation of the oxide semiconductor film is 170 °C. As a deposition gas at the time of formation of the oxide semiconductor film, an oxygen gas with a flow rate of 60 seem and an argon gas with a flow rate of 140 seem are used. Then, the oxide semiconductor film is processed into a desired shape, whereby an island-shaped oxide semiconductor film 208 is formed. Note that a wet etching apparatus is used at the time of formation of the oxide semiconductor film.

[0356] Next, a stacked film including an insulating film and a conductive film is formed over the insulating film 119 and the oxide semiconductor film 208. Then, the stacked film is processed into a desired shape, whereby island-shaped insulating films 210a and 210b, and island-shaped conductive films 212a and 212b are formed. Next, insulating films 214 and 216 are formed over the insulating film 119, the oxide semiconductor film 208, and the conductive films 212a and 212b (see FIG. 23A and FIG. 23B ).

[0357] In this embodiment, as the insulating films 210a and 210b, a silicon oxynitride film with a thickness of 50 nm is formed using a PECVD apparatus. As the conductive films 212a and 212b, an oxide semiconductor film with a thickness of 200 nm is formed using a sputtering apparatus. Note that the oxide semiconductor film has the same composition as the oxide semiconductor film 208. As the insulating film 214, a silicon nitride film with a thickness of 100 nm is formed by a PECVD apparatus. As the insulating film 216, a silicon oxynitride film with a thickness of 200 nm is formed using a PECVD apparatus.

[0358] A region of part of the oxide semiconductor film 208 and the conductive films 212a and 212b is in contact with the insulating film 214 and is added with one or both of hydrogen and nitrogen in the insulating film 214, whereby an oxide conductor (OC) is formed.

[0359] Further, the insulating films 210a and 210b are formed self-aligned using the conductive films 212a and 212b as masks.

[0360] Next, openings 282a and 282b reaching the oxide semiconductor film 208 are formed in desired regions of the insulating films 214 and 216 (see FIG. 24A and FIG. 24B ).

[0361] The openings 282a and 282b are formed using a dry etching apparatus or a wet etching apparatus.

[0362] Next, a conductive film is formed over the insulating film 216 and the oxide semiconductor film 208 so as to fill the openings 282a and 282b, and is processed into an island shape, whereby the conductive films 218a and 218b are formed (see FIG. 25A and FIG. 25B ).

[0363] As the conductive films 218a and 218b, a tungsten film with a thickness of 100 nm and a copper film with a thickness of 200 nm are formed by a sputtering method.

[0364] Next, the insulating film 136 is formed over the insulating film 216 and the conductive films 218a and 218b. Then, a desired region of the insulating film 136 is processed, and the opening 186 reaching the conductive film 218b is formed (see FIG. 26A and FIG. 26B ).

[0365] In this embodiment mode, as the insulating film 136, a photosensitive acrylic resin organic resin film with a thickness of 1.5 μm is formed.

[0366] Next, a conductive film is formed over the insulating film 136 and the conductive film 218b, and is processed into an island shape, whereby the conductive film 138 is formed (see FIG. 27A and FIG. 27B ).

[0367] As the conductive film 138 in this embodiment mode, a laminated film of an ITO film with a thickness of 10 nm, a reflective metal film (here, a metal film containing silver, palladium, and copper) with a thickness of 200 nm, and an ITO film with a thickness of 10 nm is used. The laminated film is processed into the conductive film 138 using a wet etching apparatus.

[0368] Next, the insulating film 140 is formed in an island shape over the insulating film 136 and the conductive film 138 (see FIG. 28A and FIG. 28B ).

[0369] As the insulating film 140, a photosensitive polyimide organic resin film with a thickness of 1.5 μm is used.

[0370] Next, the EL layer 142 is formed over the conductive film 138, and then the conductive film 144 is formed over the insulating film 140 and the EL layer 142, whereby the light-emitting element 160 is obtained (see FIG. 29A and FIG. 29B ).

[0371] Note that the manufacturing method of the light-emitting element 160 will be described in detail in Embodiment Mode 3.

[0372] By the above manufacturing process, the semiconductor device 200 illustrated in Figs. 16A and 16B can be manufactured. FIG. 18A and FIG. 18B .

[0373] The structure and method illustrated in this embodiment can be combined as appropriate with the structures and methods illustrated in other embodiments.

[0374] Embodiment 3

[0375] In this embodiment, reference is made to FIG. 30A and FIG. 30B to FIG. 45A and FIG. 45B A semiconductor device and a method for manufacturing a semiconductor device of one embodiment of the present application will be described.

[0376] <3-1. Structure Example 1 of Semiconductor Device>

[0377] FIG. 30A is a top view of a semiconductor device 300 of one embodiment of the present application, FIG. 30B is a cross-sectional view along the dotted line A1-A2 in FIG. 30A In addition, FIG. 30B includes a cross section in the channel length (L) direction of the transistor Tr1 and a cross section in the channel length (L) direction of the transistor Tr2.

[0378] In addition, in FIG. 30A , part of the components (e.g., an insulating film used as a gate insulating film) and part of the symbols of the components of the semiconductor device 300 are not illustrated for convenience. Note that part of the components and part of the symbols of the components are not illustrated in the top view of the semiconductor device in the following as well. FIG. 30A Similarly, part of the components and part of the symbols of the components are not illustrated.

[0379] FIG. 30A and FIG. 30B The semiconductor device 300 illustrated in FIGS. 1A and 1B includes the transistor Tr1 and the transistor Tr2. The transistor Tr1 at least partially overlaps with the transistor Tr2. In addition, the transistor Tr1 is a top-gate transistor and the transistor Tr2 is a bottom-gate transistor.

[0380] Since the transistor Tr1 at least partially overlaps with the transistor Tr2, the area of the transistor can be reduced.

[0381] The transistor Tr1 includes an insulating film 306 over a substrate 302, an oxide semiconductor film 308 over the insulating film 306, an insulating film 310 over the oxide semiconductor film 308, a conductive film 320 over the insulating film 310, and an insulating film 314 over the insulating film 306, the oxide semiconductor film 308, and the conductive film 320. The oxide semiconductor film 308 includes a channel region 308i overlapping with the conductive film 320 and in contact with the insulating film 310, a source region 308s in contact with the insulating film 314, and a drain region 308d in contact with the insulating film 314.

[0382] Further, the transistor Trl includes the insulating film 316 over the insulating film 314, the conductive film 312a electrically connected to the source region 308s in the oxide semiconductor film 308 in the opening 341a formed in the insulating film 314 and the insulating film 316, the conductive film 312b electrically connected to the drain region 308d in the oxide semiconductor film 308 in the opening 341b formed in the insulating film 314 and the insulating film 316, and the insulating film 318 over the insulating film 316, the conductive film 312a, and the conductive film 312b.

[0383] The transistor Tr2 includes the conductive film 312b, the insulating film 318 over the conductive film 312b, the oxide semiconductor film 328 over the insulating film 318, the conductive film 322a over the oxide semiconductor film 328, the conductive film 322b over the oxide semiconductor film 328, the insulating film 324 over the oxide semiconductor film 328, the conductive film 322a, and the conductive film 322b, the insulating film 326 over the insulating film 324, and the conductive film 330 over the insulating film 326. Further, the conductive film 330 is connected to the conductive film 322a through an opening 382 provided in the insulating films 324 and 326.

[0384] As FIG. 30A and FIG. 30B illustrated, the oxide semiconductor film 308 and the oxide semiconductor film 328 partially overlap with each other. Further, as FIG. 30A and FIG. 30B illustrated, it is preferable that a channel region formed in the oxide semiconductor film 308 of the transistor Trl does not overlap with a channel region formed in the oxide semiconductor film 328 of the transistor Tr2.

[0385] If the channel region of the transistor Trl overlaps with the channel region of the transistor Tr2, one transistor in operation sometimes affects the other transistor. In order to avoid the negative influence, a structure in which a space between the transistor Trl and the transistor Tr2 is increased, or a structure in which a conductive film is provided between the transistor Trl and the transistor Tr2, or the like can be used. However, in the case where the former structure is used, the thickness of the semiconductor device is increased. Thus, for example, when the semiconductor device 300 is formed over a flexible substrate or the like, a problem such as bendability is sometimes caused. In the case where the latter structure is used, there is a problem in that a process of forming the conductive film is needed and the thickness of the semiconductor device is increased.

[0386] On the other hand, in the semiconductor device 300 of one embodiment of the present application, the transistor Trl and the transistor Tr2 overlap with each other, and the channel regions of the transistors do not overlap with each other. Further, since part of each of the oxide semiconductor films forming the channel regions overlaps with each other, the area of the transistor can be appropriately reduced.

[0387] Further, the oxide semiconductor film 308 and the oxide semiconductor film 328 each include In, M (M is Al, Ga, Y, or Sn), and Zn. For example, the oxide semiconductor film 308 and the oxide semiconductor film 328 each preferably have a region where the atomic percentage of In is higher than that of M. Note that the semiconductor device of one embodiment of the present application is not limited thereto, and can have a region where the atomic percentage of In is lower than that of M, or can have a region where the atomic percentage of In is equal to that of M.

[0388] It is preferable that the composition of the oxide semiconductor film 308 be the same as or substantially the same as that of the oxide semiconductor film 328. When the composition of the oxide semiconductor film 308 is the same as that of the oxide semiconductor film 328, the manufacturing cost can be reduced. Note that the semiconductor device of one embodiment of the present application is not limited thereto, and the composition of the oxide semiconductor film 308 can be different from that of the oxide semiconductor film 328.

[0389] When the oxide semiconductor film 308 and the oxide semiconductor film 328 each have a region where the atomic percentage of In is higher than that of M, the field-effect mobility of the transistor Trl and the transistor Tr2 can be increased. Specifically, one or both of the field-effect mobilities of the transistor Trl and the transistor Tr2 can exceed 10 cm 2 / Vs, preferably, 30 cm 2 / Vs.

[0390] For example, when a transistor with high field-effect mobility described above is used for a gate driver which generates a gate signal of a display device, the display device can have a narrow frame. When a transistor with high field-effect mobility described above is used for a source driver included in a display device, which supplies a signal from a signal line (particularly, a demultiplexer connected to an output terminal of a shift register included in the source driver), the number of wirings connected to the display device can be reduced. Further, when a transistor with high field-effect mobility described above is used for one or both of a selection transistor and a driver transistor of a pixel circuit included in a display device, the display quality of the display device can be improved.

[0391] FIG. 30A and FIG. 30B The semiconductor device 300 illustrated in FIG. 26 can be used as a pixel circuit of a display device as appropriate. FIG. 30A and FIG. 30B The layout illustrated in FIG. 27 can increase the pixel density of a display device. For example, even when the pixel density of a display device exceeds 1000 ppi (pixel per inch) or 2000 ppi, the display device can have a high resolution by FIG. 31 and FIG. 30AThe layout shown can also improve the aperture ratio of the pixels. Note that ppi is a unit indicating the number of pixels per inch.

[0392] <3-2. Pixel circuit of display device>

[0393] Reference will be made to FIG. 30B to the case where FIG. 31 and FIG. 31 The case where the semiconductor device 300 shown in FIG. 1 is used for a pixel circuit of a display device will be described with reference to FIG. 2.

[0394] FIG. 31 is a circuit diagram showing an example of the case where the semiconductor device 300 is used for a pixel circuit of a display device.

[0395] FIG. 30A The semiconductor device 300 shown in FIG. 1 includes a transistor Trl, a transistor Tr2, a capacitor Csl, and a light-emitting element 360. Note that FIG. 30B An example in which two semiconductor devices 300 are adjacent in the column direction is shown. The semiconductor devices 300 are used as pixels (also referred to as subpixels). Although FIG. 31 and FIG. 30A The capacitor Csl is not illustrated in FIG. 1, but can be formed using a parasitic capacitor between the conductive film 312b included in the transistor Trl and the conductive film 322b included in the transistor Tr2.

[0396] FIG. 30B The circuit diagram of FIG. 2 includes a data line DL_Y-1 to which a data signal of a pixel is input, a data line DL_Y to which a data signal of an adjacent pixel is input, an anode line ANODE_X-1 to which a potential is supplied to a light-emitting element, an anode line ANODE_X to which a potential is supplied to an adjacent light-emitting element, and a scan line GL_X to which a scan signal is supplied to a pixel.

[0397] One of the source and drain electrodes of the transistor Trl is electrically connected to the data line DL_Y-1. The first and second gate electrodes of the transistor Trl are electrically connected to the scan line GL_X. The transistor Trl controls writing of a data signal.

[0398] One of a pair of electrodes of the capacitor Csl is electrically connected to the other of the source and drain electrodes of the transistor Trl. The other of the pair of electrodes of the capacitor Csl is electrically connected to the second gate electrode (also referred to as a back gate electrode) of the transistor Tr2. The capacitor Csl has a function of a storage capacitor that holds a data signal written.

[0399] One of the source and drain electrodes of the transistor Tr2 is electrically connected to the anode line ANODE_X-1.

[0400] One electrode of the pair of electrodes of the light-emitting element 360 is electrically connected to the other of the source and drain electrodes of the transistor Tr2, and the other electrode of the light-emitting element 360 is electrically connected to the cathode wire CATHODE. Furthermore, one electrode of the pair of electrodes of the light-emitting element 360 is electrically connected to the other of the pair of electrodes of the capacitor Cs1.

[0401] The above structure is to FIG. 30A and FIG. 30B The semiconductor device 300 shown is used as an example of a display device pixel.

[0402] <3-3. Structure of Semiconductor Devices>

[0403] Furthermore, regarding FIG. 30A and FIG. 30B The semiconductor device 300 shown will be described in detail. FIG. 30A and FIG. 30B When the semiconductor device 300 shown is used for pixels in a display device, for example, the channel length (L) and channel width (W) of the transistor, as well as the line width of the wiring and electrodes connected to the transistor, can be larger. For example, when... FIG. 30A and FIG. 30B When transistors Tr1 and Tr2 are arranged in an overlapping manner as shown, the line width can be increased, etc., compared with the case where transistors Tr1 and Tr2 are arranged on the same plane, so the non-uniformity of the processing dimensions can be reduced.

[0404] Furthermore, one or both of the conductive and insulating films can be used together between transistors Tr1 and Tr2, thus reducing the number of masks or processes.

[0405] For example, in transistor Tr1, conductive film 320 is used as the gate electrode, conductive film 312a as the source electrode, and conductive film 312b as the drain electrode. Furthermore, in transistor Tr1, insulating film 310 is used as the gate insulating film. In transistor Tr2, conductive film 312b is used as the first gate electrode, conductive film 322a as the source electrode, conductive film 322b as the drain electrode, and conductive film 330 as the second gate electrode. Furthermore, in transistor Tr2, insulating film 318 is used as the first gate insulating film, and insulating films 324 and 326 are used as the second gate insulating films.

[0406] Note that in this specification, etc., insulating film 310 is sometimes referred to as the first insulating film, insulating film 318 as the second insulating film, and insulating films 324 and 326 as the third insulating film.

[0407] An insulating film 334 is disposed on the conductive film 330, and an insulating film 336 is disposed on the insulating film 334. An opening 384 is provided in the insulating films 334 and 336 to reach the conductive film 330. Furthermore, a conductive film 338 is disposed on the insulating film 336. In addition, the conductive film 338 is connected to the conductive film 330 in the opening 384.

[0408] Furthermore, an insulating film 340, an EL layer 342, and a conductive film 344 are disposed on the conductive film 338. The insulating film 340 covers a portion of the side end of the conductive film 338 and prevents short circuits between adjacent pixels. The EL layer 342 emits light. The conductive film 338, the EL layer 342, and the conductive film 344 constitute the light-emitting element 360. The conductive film 338 serves as one electrode of the light-emitting element 360. The conductive film 344 serves as the other electrode of the light-emitting element 360.

[0409] As described above, one aspect of the present invention can combine top-gate transistors and bottom-gate transistors.

[0410] As described above, in one aspect of the semiconductor device of the present invention, multiple transistors are stacked, thereby reducing the area of ​​the transistors. Furthermore, since one or both of the insulating and conductive films are shared among the multiple transistors, the number of masks or processes can be reduced.

[0411] <3-4. Structure of the gate electrode>

[0412] like FIG. 30A and FIG. 30B As shown, transistors Tr1 and Tr2 each have two gate electrodes.

[0413] Here, refer to FIG. 32 and FIG. 32 as well as FIG. 30A The effects of the two gate electrodes are explained.

[0414] also, FIG. 32 It is along FIG. 32 The cross-sectional view of the dotted line B1-B2. FIG. 30B This includes the cross-section along the channel width (W) direction of transistor Tr2.

[0415] In addition, such as FIG. 33 As shown, the oxide semiconductor film 328 is located opposite to the conductive films 312b and 330, and is sandwiched between the conductive films used as two gate electrodes. The channel width lengths of both the conductive films 312b and 330 are greater than the channel width length of the oxide semiconductor film 328. The entire oxide semiconductor film 328 is covered by the conductive films 312b and 330 through insulating films 318, 324, and 326.

[0416] In other words, the conductive film 312b and the conductive film 330 have a region positioned outside the side end portion of the oxide semiconductor film 328.

[0417] With the above structure, the oxide semiconductor film 328 included in the transistor Tr2 can be electrically surrounded by the electric field of the conductive film 312b and the conductive film 330. A device structure in which a transistor in which a first gate electrode and a second gate electrode like the transistor Tr2 electrically surround an oxide semiconductor film forming a channel region is referred to as a surrounded channel (S-channel) structure.

[0418] Since the transistor Tr2 has the S-channel structure, the electric field for causing a channel can be effectively applied to the oxide semiconductor film 328 by the conductive film 312b serving as the first gate electrode. Thus, the current drivability of the transistor Tr2 is improved, so that a high on-state current characteristic can be obtained. Furthermore, since the on-state current can be increased, the size of the transistor Tr2 can be reduced. In addition, since the transistor Tr2 has a structure in which the oxide semiconductor film 328 is surrounded by the conductive film 312b serving as the first gate electrode and the conductive film 330 serving as the second gate electrode, the mechanical strength of the transistor Tr1 can be improved.

[0419] Although in the transistor Tr2 illustrated in FIG. 1, the conductive film 330 serving as the second gate electrode is electrically connected to the conductive film 322a serving as the source electrode or the drain electrode of the transistor Tr2, one embodiment of the present application is not limited to this. For example, the first gate electrode can be connected to the second gate electrode. At this time, an opening is formed in the insulating films 318, 324, and 326 so that the conductive film 330 serving as the second gate electrode can be electrically connected to the conductive film 312b serving as the first gate electrode in the opening. Thus, the conductive film 312b and the conductive film 330 are supplied with the same potential. FIG. 30A

[0420] <3-5. Constituent Elements of Semiconductor Device>

[0421] Next, the constituent elements of the semiconductor device of this embodiment are described in detail.

[0422] [Substrate]

[0423] ​There is no particular limitation on the material of the substrate 302 as long as it is a material having heat resistance capable of withstanding a subsequent heat treatment. For example, as the substrate 302, a glass substrate, a ceramic substrate, a quartz substrate, a sapphire substrate can be used. As the substrate 302, a single-crystal semiconductor substrate or a polycrystal semiconductor substrate composed of silicon or silicon carbide, a compound semiconductor substrate composed of silicon germanium or the like, an SOI (Silicon On Insulator) substrate or the like can be used. A substrate provided with a semiconductor element on the substrate can also be used as the substrate 302. When a glass substrate is used as the substrate 302, a large-sized display device can be manufactured using a glass substrate of the following size: 6th generation (1500 mm x 1850 mm), 7th generation (1870 mm x 2200 mm), 8th generation (2200 mm x 2400 mm), 9th generation (2400 mm x 2800 mm), 10th generation (2950 mm x 3400 mm).

[0424] As the substrate 302, a flexible substrate can also be used, and the semiconductor device 300 can be directly provided on the flexible substrate. Alternatively, a separation layer can be provided between the substrate 302 and the semiconductor device 300. The separation layer can be used in a case where a part or all of the semiconductor device formed on the separation layer is separated from the substrate 302 and transplanted onto another substrate. At this time, the semiconductor device 300 can be transplanted onto a substrate having low heat resistance or a flexible substrate.

[0425] <Conductive film>

[0426] The conductive film 312a, the conductive film 312b, the conductive film 320, the conductive film 322a, the conductive film 322b, the conductive film 330, the conductive film 338, and the conductive film 344 can be formed using a metal element selected from chromium (Cr), copper (Cu), aluminum (Al), gold (Au), silver (Ag), zinc (Zn), molybdenum (Mo), tantalum (Ta), titanium (Ti), tungsten (W), manganese (Mn), nickel (Ni), iron (Fe), cobalt (Co), an alloy containing the above metal element as a component, or an alloy containing a combination of the above metal elements.

[0427] The conductive film 312a, the conductive film 312b, the conductive film 320, the conductive film 322a, the conductive film 322b, the conductive film 330, the conductive film 338, and the conductive film 344 can be formed using an oxide conductor containing indium and tin, an oxide conductor containing tungsten and indium, an oxide conductor containing tungsten, indium, and zinc, an oxide conductor containing titanium and indium, an oxide conductor containing titanium, indium, and tin, an oxide conductor containing indium and zinc, an oxide conductor containing silicon, indium, and tin, an oxide conductor containing indium, gallium, and zinc, or the like.

[0428] In particular, the above oxide conductor is suitable for the conductive film 320 and the conductive film 330. Here, the oxide conductor is described. In this specification and the like, the oxide conductor can be referred to as an OC (oxide conductor). For example, the oxide conductor is obtained by forming oxygen vacancies in an oxide semiconductor and then adding hydrogen to the oxygen vacancies to form a donor level in the vicinity of the conduction band. As a result, the conductivity of the oxide semiconductor is increased and the oxide semiconductor becomes a conductor. The oxide semiconductor which becomes a conductor can be referred to as an oxide conductor. In general, an oxide semiconductor has a large energy gap and thus transmits visible light. The oxide conductor is an oxide semiconductor which has a donor level in the vicinity of the conduction band. Thus, the influence of absorption due to the donor level is small in the oxide conductor, and thus the oxide conductor has the same visible light-transmitting property as the oxide semiconductor.

[0429] As the conductive film 312a, the conductive film 312b, the conductive film 322a, the conductive film 322b, the conductive film 330, the conductive film 338, and the conductive film 344, a Cu-X alloy film (X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti) can be used. By using the Cu-X alloy film, a thin film can be processed by a wet etching process, so that manufacturing cost can be reduced.

[0430] In particular, the above Cu-X alloy film is suitable for one or more of the conductive film 312a, the conductive film 312b, the conductive film 322a, the conductive film 322b, and the conductive film 330. As the Cu-X alloy film, a Cu-Mn alloy film is particularly preferable.

[0431] As the material of one or more of the conductive film 312a, the conductive film 312b, the conductive film 320, the conductive film 322a, the conductive film 322b, and the conductive film 330, one or more of aluminum, copper, titanium, tungsten, tantalum, and molybdenum among the above metal elements is particularly preferable.

[0432] As one or more of the conductive film 312a, the conductive film 312b, the conductive film 320, the conductive film 322a, the conductive film 322b, and the conductive film 330, a tantalum nitride film containing nitrogen and tantalum is preferably used. The tantalum nitride film has conductivity and has high barrier properties against copper and hydrogen. Since the amount of hydrogen released from the tantalum nitride film is small, the tantalum nitride film is most suitable for use as a metal film in contact with the oxide semiconductor film 308 or a metal film in the vicinity of the oxide semiconductor film 308.

[0433] [Insulating film]

[0434] As the insulating films 306, 314, 316, 318, 324, 326, 334, 336, and 340, an insulating layer including at least one of a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, a hafnium oxide film, a yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film formed by a plasma CVD method or a sputtering method can be used.

[0435] The insulating film 306 is used as a barrier film for inhibiting the passage of oxygen. For example, in the case where one or more of the insulating film 314, the insulating film 316, the oxide semiconductor film 308, the oxide semiconductor film 328, the insulating film 324, and the insulating film 326 have a region with excess oxygen, the insulating film 306 can inhibit the passage of oxygen.

[0436] Further, the insulating film in contact with one or both of the oxide semiconductor film 308 and the oxide semiconductor film 328 is preferably an oxide insulating film and preferably has a region with an oxygen content exceeding the stoichiometric composition (a region with excess oxygen). In other words, the oxide insulating film having a region with excess oxygen can release oxygen.

[0437] For example, the region with excess oxygen of the oxide insulating film can be formed by forming an insulating film in an oxygen atmosphere, by performing heat treatment on the insulating film in an oxygen atmosphere after the formation of the insulating film, or by adding oxygen to the insulating film after the formation of the insulating film. As a method for adding oxygen to the insulating film after the formation of the insulating film, plasma treatment is preferable.

[0438] The insulating film used as the gate insulating film of the transistor Trl and the transistor Tr2 can be formed using hafnium oxide. In the case where hafnium oxide is used as the insulating film used as the gate insulating film, the following effects are obtained.

[0439] The relative dielectric constant of hafnium oxide is higher than that of silicon oxide and silicon oxynitride. Accordingly, the thickness of the insulating film formed using hafnium oxide can be larger than that of the insulating film formed using silicon oxide, whereby the leakage current caused by a tunnel current can be reduced. That is, a transistor with small off-state current can be manufactured. Furthermore, hafnium oxide with a crystal structure has a higher relative dielectric constant than hafnium oxide with an amorphous structure. Thus, in order to manufacture a transistor with small off-state current, it is preferable to use hafnium oxide with a crystal structure. As examples of the crystal structure, monoclinic and cubic crystal systems can be given. Note that one embodiment of the present application is not limited to the above examples.

[0440] The insulating film used as the gate insulating film of the transistor Tr1 and the transistor Tr2 can be formed using silicon nitride. In the case where silicon nitride is used as the insulating film used as the gate insulating film, the following effects are obtained. The relative dielectric constant of silicon nitride is higher than that of silicon oxide and a thickness necessary to obtain the same electrostatic capacity as that of silicon oxide is larger. Thus, the thickness of the gate insulating film can be increased. Thus, the electrostatic breakdown of the transistor Tr1 and the transistor Tr2 can be prevented by suppressing the decrease in the insulating withstand voltage of the transistor Tr1 and the transistor Tr2 and increasing the insulating withstand voltage.

[0441] The insulating films 310, 316, 318, 324, and 326 have a function of supplying oxygen to the oxide semiconductor film 308 and / or the oxide semiconductor film 328. That is, the insulating films 310, 316, 318, 324, and 326 contain oxygen. The insulating films 310 and 324 are insulating films through which oxygen can pass. Note that the insulating film 310 is also used as a film for preventing damage to the oxide semiconductor film 308 when the conductive film 320 is formed in a later step. The insulating film 324 is also used as a film for preventing damage to the oxide semiconductor film 328 when the insulating film 326 is formed in a later step.

[0442] As the insulating films 310 and 324, a silicon oxide film, a silicon oxynitride film, or the like having a thickness of greater than or equal to 5 nm and less than or equal to 150 nm, preferably greater than or equal to 5 nm and less than or equal to 50 nm can be used.

[0443] Further, it is preferable that the amount of defects in the insulating films 310 and 324 be small, and typically, the spin density of a signal attributed to a silicon dangling bond and appearing at g = 2.001 measured by electron spin resonance (ESR: electron spin resonance) is preferably 3 x 10 17 spins / cm 3 The following. This is because if the defect density of the insulating films 314 and 324 is high, oxygen is bonded to the defects, which reduces the amount of oxygen passing through the insulating film 314.

[0444] The insulating films 310 and 324 can be formed using an oxide insulating film in which the density of states attributed to nitrogen oxide is low. Note that the density of states attributed to nitrogen oxide is sometimes formed between the energy (E V_OS ) of the valence band maximum of the oxide semiconductor film and the energy (E C_OS ) of the conduction band minimum. As the oxide insulating film, a silicon oxynitride film in which the amount of release of nitrogen oxide is small, an aluminum oxynitride film in which the amount of release of nitrogen oxide is small, or the like can be used.

[0445] Further, in thermal desorption spectroscopy (TDS), a silicon oxynitride film in which the amount of release of nitrogen oxide is small is a film in which the amount of release of ammonia is larger than that of nitrogen oxide, and typically, the amount of release of ammonia is 1 x 1018 cm -3 above and 5 x 10 19 cm -3 above. Note that the above amount of released ammonia is the total amount of ammonia released at a temperature of the heat treatment in the TDS in a range of 50 °C to 650 °C or 50 °C to 550 °C. The above amount of released ammonia is the total amount of the amount of released ammonia converted into ammonia molecules in the TDS.

[0446] nitrogen oxide (NO x , x is greater than or equal to 0 and less than or equal to 2, preferably greater than or equal to 1 and less than or equal to 2), typically NO2or NO, forms an energy level in the insulating films 310 and 324. The energy level is located in the energy gap of the oxide semiconductor films 308 and 328. Thus, when the nitrogen oxide diffuses to the interface between the insulating film 310 and the oxide semiconductor film 308 or the interface between the insulating film 324 and the oxide semiconductor film 328, an electron on the side of the insulating film 310 or 324 is sometimes trapped by the energy level. As a result, the trapped electron remains in the vicinity of the interface between the insulating film 310 and the oxide semiconductor film 308 or the interface between the insulating film 324 and the oxide semiconductor film 328, and thus the threshold voltage of the transistor is shifted in the positive direction.

[0447] In the heat treatment, the nitrogen oxide reacts with ammonia and oxygen. Since the nitrogen oxide contained in the insulating film 324 reacts with ammonia contained in the insulating film 326 in the heat treatment, the nitrogen oxide contained in the insulating film 324 is reduced. Thus, an electron is not easily trapped at the interface between the insulating film 324 and the oxide semiconductor film 328.

[0448] By using the above oxide insulating film, the insulating films 310 and 324 can reduce the shift of the threshold voltage of the transistor, and thus can reduce the variation in electrical characteristics of the transistor.

[0449] In the ESR spectrum of the insulating film 310 or 324 at 100 K, a first signal with a g value of greater than or equal to 2.037 and less than or equal to 2.039, a second signal with a g value of greater than or equal to 2.001 and less than or equal to 2.003, and a third signal with a g value of greater than or equal to 1.964 and less than or equal to 1.966 are observed by the heat treatment in the manufacturing process of the transistor, typically the heat treatment at higher than or equal to 300 °C and lower than 350 °C. The separation width of the first signal and the second signal and the separation width of the second signal and the third signal obtained by X-band ESR measurement are approximately 5 mT. The sum of the spin densities of the first signal with a g value of greater than or equal to 2.037 and less than or equal to 2.039, the second signal with a g value of greater than or equal to 2.001 and less than or equal to 2.003, and the third signal with a g value of greater than or equal to 1.964 and less than or equal to 1.966 is lower than 1 x 10 18 spins / cm 3 , typically 1 x 10 17spins / cm 3 Above and below 1×10 18 spins / cm 3 .

[0450] In ESR spectra below 100 K, the sum of the spin densities of the first signal with a g value of 2.037 to 2.039, the second signal with a g value of 2.001 to 2.003, and the third signal with a g value of 1.964 to 1.966 is equivalent to the sum of the spin densities of signals originating from nitrogen oxides (NOx, x greater than 0 and less than 2, preferably 1 to 2). Typical examples of nitrogen oxides include nitric oxide and nitrogen dioxide. It can be considered that the lower the total number of spin densities of the first signal with a g value of 2.037 to 2.039, the second signal with a g value of 2.001 to 2.003, and the third signal with a g value of 1.964 to 1.966, the lower the nitrogen oxide content in the oxide insulating film.

[0451] The nitrogen concentration of the aforementioned oxide insulating film, measured using SIMS, was 6 × 10⁻⁶. 20 atoms / cm 3 the following.

[0452] By forming the above-mentioned oxide insulating film using PECVD with silane and nitrous oxide at a substrate temperature of 220°C or higher and 350°C or lower, a dense and hard oxide insulating film can be formed.

[0453] The insulating film 314 contains nitrogen or hydrogen. For example, a nitride insulating film can be used as the insulating film 314. This nitride insulating film can be formed using silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, etc. The hydrogen concentration in the insulating film 314 is preferably 1 × 10⁻⁶. 22 atoms / cm 3 That's all. Furthermore, the insulating film 314 contacts the source region 308s and drain region 308d in the oxide semiconductor film 308. Additionally, the insulating film 314 has a region that contacts the conductive film 320. Therefore, the hydrogen concentration in the source region 308s, drain region 308d, and conductive film 320 that are in contact with the insulating film 314 increases, thereby increasing the carrier density in the source region 308s, drain region 308d, and conductive film 320. Since the source region 308s, drain region 308d, and conductive film 320 are in contact with the insulating film 314, they sometimes have regions with the same hydrogen concentration.

[0454] The insulating films 316, 318, and 326 are formed using an oxide insulating film having an oxygen content exceeding the stoichiometric composition. By heating, part of the oxygen is released from the oxide insulating film having an oxygen content exceeding the stoichiometric composition. The amount of oxygen released from the oxide insulating film having an oxygen content exceeding the stoichiometric composition is 1.0 x 10 19 cm -3 or more and 3.0 x 10 20 cm -3 or less. Note that the amount of oxygen released described above is the total amount of oxygen released at a temperature of the heat treatment in the TDS ranging from 50 °C to 650 °C or from 50 °C to 550 °C. The amount of oxygen released described above is the total amount of the amount of oxygen released in the TDS converted into oxygen molecules.

[0455] As the insulating films 316, 318, and 326, a silicon oxide film, a silicon oxynitride film, or the like having a thickness of 30 nm to 500 nm, preferably, 50 nm to 400 nm can be used.

[0456] Further, it is preferable that the amount of defects in the insulating films 316, 318, and 326 be small, and typically, the spin density of a signal attributed to a silicon dangling bond and appearing at g = 2.001 measured by ESR be lower than 1.5 x 10 18 spins / cm 3 , more preferably, 1 x 10 18 spins / cm 3 or less.

[0457] Since the insulating films 324 and 326 can be formed using insulating films containing the same kind of material, the interface between the insulating films 324 and 326 is not always clearly confirmed. Thus, in this embodiment mode, the interface between the insulating films 324 and 326 is indicated by a dotted line.

[0458] The insulating film 334 is used as a protective insulating film of the transistor Trl and the transistor Tr2.

[0459] The insulating film 334 contains one or both of hydrogen and nitrogen. In addition, the insulating film 334 contains nitrogen and silicon. The insulating film 334 has a function of blocking oxygen, hydrogen, water, alkali metals, alkaline earth metals, and the like. By providing the insulating film 334, diffusion of oxygen from the oxide semiconductor films 308 and 328 to the outside can be prevented, and diffusion of oxygen contained in the insulating films 310, 316, 324, and 326 to the outside can be prevented, and in addition, entry of hydrogen, water, and the like from the outside into the oxide semiconductor films 308 and 328 can be prevented.

[0460] The insulating film 334 can be formed using, for example, a nitride insulating film. The nitride insulating film is formed using silicon nitride, silicon nitride oxide, aluminum nitride, aluminum nitride oxide, or the like.

[0461] [Oxide semiconductor film]

[0462] The oxide semiconductor films 308 and 328 can be formed using the above-described materials.

[0463] When the oxide semiconductor films 308 and 328 each include an In-M-Zn oxide, the atomic ratio of the metal elements of a sputtering target used for forming the In-M-Zn oxide is preferably In > M. The atomic ratio of the metal elements of such a sputtering target is, for example, In:M:Zn = 2:1:3, In:M:Zn = 3:1:2, or In:M:Zn = 4:2:4.1.

[0464] When the oxide semiconductor film 308 and the oxide semiconductor film 328 each include an In-M-Zn oxide, the atomic ratio of the metal elements of a sputtering target used for forming the In-M-Zn oxide is preferably In ≤ M. The atomic ratio of the metal elements of such a sputtering target is, for example, In:M:Zn = 1:1:1, In:M:Zn = 1:1:1.2, In:M:Zn = 1:3:2, In:M:Zn = 1:3:4, or In:M:Zn = 1:3:6.

[0465] When the oxide semiconductor film 308 and the oxide semiconductor film 328 each include an In-M-Zn oxide, a target including a polycrystalline In-M-Zn oxide is preferably used as a sputtering target. By using a target including a polycrystalline In-M-Zn oxide, the oxide semiconductor films 308 and 328 having crystallinity can be easily formed. Note that the atomic ratio of the metal elements in the formed oxide semiconductor films 308 and 328 varies within a range of ±40 % of the atomic ratio of the metal elements of the above-described sputtering target. For example, when a sputtering target whose atomic ratio of In, Ga, and Zn is 4:2:4.1 is used as a sputtering target for the oxide semiconductor films 308 and 328, the atomic ratio of In, Ga, and Zn in the oxide semiconductor films 308 and 328 is sometimes 4:2:3 or in the vicinity of 4:2:3.

[0466] The energy gap of the oxide semiconductor films 308 and 328 is 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. By using an oxide semiconductor having such a wide energy gap, the off-state current of the transistors Tr1 and Tr2 can be reduced.

[0467] The thickness of the oxide semiconductor films 308 and 328 is greater than or equal to 3 nm and less than or equal to 200 nm, preferably greater than or equal to 3 nm and less than or equal to 100 nm, and more preferably greater than or equal to 3 nm and less than or equal to 50 nm.

[0468] Hydrogen contained in the oxide semiconductor films 308 and 328 reacts with oxygen bonded to a metal atom to generate water, and at the same time, oxygen vacancies are formed in a lattice where oxygen is detached (or an oxygen-detached portion). When hydrogen enters the oxygen vacancies, electrons serving as carriers are sometimes generated. In addition, part of the hydrogen is sometimes bonded to oxygen bonded to a metal atom, and electrons serving as carriers are generated. Thus, a transistor including an oxide semiconductor film containing hydrogen tends to have a normally-on characteristic. Thus, it is preferable to reduce hydrogen in the oxide semiconductor films 308 and 328 as much as possible.

[0469] Specifically, in the oxide semiconductor films 308 and 328, the hydrogen concentration measured by SIMS is 2 x 10 20 atoms / cm 3 Hereinafter, the hydrogen concentration is preferably 5 x 10 19 atoms / cm 3 Hereinafter, the hydrogen concentration is more preferably 1 x 10 19 atoms / cm 3 Hereinafter, the hydrogen concentration is more preferably 5 x 10 18 atoms / cm 3 Hereinafter, the hydrogen concentration is more preferably 1 x 10 18 atoms / cm 3 Hereinafter, the hydrogen concentration is more preferably 5 x 10 17 atoms / cm 3 Hereinafter, the hydrogen concentration is further preferably 1 x 10 16 atoms / cm 3 Hereinafter.

[0470] When the oxide semiconductor films 308 and 328 contain silicon or carbon which is one of Group 14 elements, oxygen vacancies are increased in the oxide semiconductor films 308 and 328, so that the oxide semiconductor films 308 and 328 become n-type films. Thus, the silicon concentration measured by SIMS analysis in the oxide semiconductor films 308 and 328 is 2 x 10 18 atoms / cm 3 Hereinafter, the silicon concentration is preferably 2 x 10 17 atoms / cm 3 Hereinafter. The carbon concentration measured by SIMS analysis in the oxide semiconductor films 308 and 328 is 2 x 10 18 atoms / cm 3 Hereinafter, the carbon concentration is preferably 2 x 10 17 atoms / cm 3 Hereinafter.

[0471] In addition, the concentration of an alkali metal or an alkaline earth metal measured by SIMS analysis in the oxide semiconductor film 308 and the oxide semiconductor film 328 is 1 x 10 18 atoms / cm 3The following is preferably 2 x 10 16 atoms / cm 3 The following. Alkali metals and alkaline earth metals sometimes generate carriers when bonded to the oxide semiconductor, in which case the off-state current of the transistor increases. Thus, it is preferable to reduce the concentration of alkali metals or alkaline earth metals in the oxide semiconductor films 308 and 328.

[0472] The oxide semiconductor film 308 and the oxide semiconductor film 328 can have a non-single-crystal structure, for example. Examples of the non-single-crystal structure include a CAAC-OS (c-axis-aligned crystalline oxide semiconductor), a polycrystalline structure, a microcrystalline structure, and an amorphous structure. In the non-single-crystal structure, the amorphous structure has the highest density of defect states, and the CAAC-OS has the lowest density of defect states.

[0473] The various films such as the conductive film, the insulating film, and the oxide semiconductor film described above can be formed by a sputtering method, a plasma enhanced chemical vapor deposition (PECVD) method, or a thermal CVD method. As an example of the thermal CVD method, a metal organic chemical vapor deposition (MOCVD) method or an atomic layer deposition (ALD) method can be given.

[0474] The thermal CVD method is a film formation method which does not use plasma, and thus has an advantage that defects caused by plasma damage are not generated.

[0475] The film formation by the thermal CVD method can be performed in such a manner that source gas and oxidizer are simultaneously supplied into a processing chamber, the pressure in the processing chamber is set to be atmospheric pressure or reduced pressure, and reaction is caused in the vicinity of a substrate or on the substrate.

[0476] Further, the film formation by the ALD method can be performed in such a condition that the pressure in the processing chamber is set to be atmospheric pressure or reduced pressure, and source gas for reaction is used.

[0477] Various films such as the conductive film, the insulating film, the oxide semiconductor film, and the like described in this embodiment can be formed by a thermal CVD method such as an MOCVD method or an ALD method. For example, an In-Ga-Zn-O film can be formed using trimethyl indium, trimethyl gallium, and dimethyl zinc. The chemical formula of trimethyl indium is In(CH3)3. The chemical formula of trimethyl gallium is Ga(CH3)3. In addition, the chemical formula of dimethyl zinc is Zn(CH3)2. Instead of trimethyl gallium, triethyl gallium (chemical formula: Ga(C2H5)3) can be used, and instead of dimethyl zinc, diethyl zinc (chemical formula: Zn(C2H5)2) can be used, not limited to the above combination.

[0478] For example, when a hafnium oxide film is formed by using a film formation apparatus of an ALD method, two kinds of gases are used: ozone (O3) which is used as an oxidizer; and a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide, hafnium tetra-dimethylamide (TDMAH), or the like). Further, the chemical formula of hafnium tetra-dimethylamide is Hf[N(CH3)2]4. As an example of another material liquid, there is hafnium tetra(ethylmethylamide).

[0479] For example, when an aluminum oxide film is formed by using a film formation apparatus of an ALD method, two kinds of gases are used: H2O which is used as an oxidizer; and a source gas obtained by vaporizing a liquid containing a solvent and an aluminum precursor compound (e.g., trimethylaluminum (TMA)). Further, the chemical formula of trimethylaluminum is Al(CH3)3. As an example of another material liquid, there are aluminum tris(dimethylamide), aluminum triisobutyl, and aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedione).

[0480] For example, when a silicon oxide film is formed by using a film formation apparatus of an ALD method, hexachlorodisilane is attached to a film formation surface, chlorine included in the attached material is removed, and radicals of an oxidizing gas (e.g., O2, dinitrogen monoxide) are supplied to react with the attached material.

[0481] For example, when a tungsten film is formed by using a film formation apparatus of an ALD method, a WF6gas and a B2H6gas are used to form an initial tungsten film, and then a WF6gas and an H2gas are used to form a tungsten film. Note that a SiH4gas can be used instead of the B2H6gas.

[0482] For example, when forming an oxide semiconductor film such as an In-Ga-ZnO film using an ALD (Alternating Discharge) method, In(CH3)3 gas and O3 gas are introduced sequentially and repeatedly to form an In-O layer, then Ga(CH3)3 gas and O3 gas are used to form a GaO layer, and finally Zn(CH3)2 gas and O3 gas are used to form a ZnO layer. Note that the order of these layers is not limited to the example above. Furthermore, these gases can be mixed to form mixed compound layers such as In-Ga-O layers, In-Zn-O layers, Ga-Zn-O layers, etc. H2O gas obtained by bubbling with an inert gas such as Ar can be used instead of O3 gas, but O3 gas that does not contain H is preferred. Alternatively, In(C2H5)3 gas can be used instead of In(CH3)3 gas. Similarly, Ga(C2H5)3 gas can be used instead of Ga(CH3)3 gas. Additionally, Zn(CH3)2 gas can also be used.

[0483] <3-6. Example 2 of Semiconductor Device Structure>

[0484] Next, refer to FIG. 30B right FIG. 33 and FIG. 30B A modified example of the semiconductor device 300 shown will be described.

[0485] FIG. 33 yes FIG. 33 A cross-sectional view of a modified example of the semiconductor device 300 shown.

[0486] FIG. 34A The diagram shows a structure without a conductive film 330, which serves as the second gate electrode of the transistor Tr2 included in the semiconductor device 300, and an insulating film 334 on the conductive film 330. Furthermore, in FIG. 34B In the structure shown, an opening 383 is formed in insulating films 324, 326, and 336 instead of opening 382 in insulating films 324 and 326, and opening 384 in insulating films 334 and 336. By employing a structure including an opening, manufacturing steps can be reduced, and therefore it is preferred.

[0487] <3-7. Structural Example 3 of a Semiconductor Device>

[0488] Next, refer to FIG. 35A and FIG. 35B and FIG. 30A and FIG. 30B right FIG. 34A and FIG. 34B A modified example of the semiconductor device 300 shown will be described.

[0489] The stacked structure of oxide semiconductor films will be described below.

[0490] FIG. 34A and FIG. 34B is a cross-sectional view in the channel length (L) direction of the transistor Tr2 included in the semiconductor device 300.

[0491] FIG. 35A The oxide semiconductor film 328 of the transistor Tr2 is shown to include an oxide semiconductor film 328a, an oxide semiconductor film 328b over the oxide semiconductor film 328a, and an oxide semiconductor film 328c over the oxide semiconductor film 328b. In other words, the oxide semiconductor film 328 has a three-layer structure.

[0492] FIG. 35B The oxide semiconductor film 328 of the transistor Tr2 is shown to include an oxide semiconductor film 328b and an oxide semiconductor film 328c over the oxide semiconductor film 328b. In other words, the oxide semiconductor film has a two-layer structure.

[0493] FIG. 35A and FIG. 35B An example of a band structure of the oxide semiconductor film 328 and the insulating film in contact with the oxide semiconductor film 328 is shown.

[0494] FIG. 35A An example of a band diagram in the film thickness direction of a stack including the insulating film 318, the oxide semiconductor films 328a, 328b, and 328c, and the insulating film 324 is shown. FIG. 35B An example of a band diagram in the film thickness direction of a stack including the insulating film 318, the oxide semiconductor films 328b and 328c, and the insulating film 324 is shown. For easy understanding, the energy levels (Ec) of the conduction band bottoms of the insulating film 318, the oxide semiconductor films 328a, 328b, 328c, and the insulating film 324 are shown in the band diagram.

[0495] FIG. 35A is a band diagram of a structure in which a silicon oxide film is used as the insulating films 318 and 324, an oxide semiconductor film formed using a metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 1:3:2 is used as the oxide semiconductor film 328a, an oxide semiconductor film formed using a metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 4:2:4.1 is used as the oxide semiconductor film 328b, and an oxide semiconductor film formed using a metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 1:3:2 is used as the oxide semiconductor film 328c.

[0496] FIG. 35Bis a band diagram of the following structure: as the insulating films 318 and 324, silicon oxide films are used, as the oxide semiconductor film 328b, an oxide semiconductor film formed using a metal oxide target whose atomic proportions of metal elements are In:Ga:Zn = 4:2:4.1 is used, and as the oxide semiconductor film 328c, a metal oxide film formed using a metal oxide target whose atomic proportions of metal elements are In:Ga:Zn = 1:3:2 is used.

[0497] As FIG. 35A and FIG. 35B indicated, the energy levels of the conduction band bottom gently change between the oxide semiconductor film 328a and the oxide semiconductor film 328b and between the oxide semiconductor film 328b and the oxide semiconductor film 328c. In other words, the energy levels of the conduction band bottom continuously change or continuously join. In order to achieve such a band structure, impurities that form a defect level such as a trap center or a recombination center are not present at the interface between the oxide semiconductor film 328a and the oxide semiconductor film 328b or at the interface between the oxide semiconductor film 328b and the oxide semiconductor film 328c.

[0498] In order to form a continuous junction between the oxide semiconductor film 328a and the oxide semiconductor film 328b and between the oxide semiconductor film 328b and the oxide semiconductor film 328c, a multi-chamber deposition apparatus (sputtering apparatus) provided with a load lock chamber is used to continuously stack the films in a manner such that each film is not exposed to the atmosphere.

[0499] By employing FIG. 34A and FIG. 34B a band structure, the oxide semiconductor film 328b becomes a well, and in a transistor using the above-described stacked structure, a channel region is formed in the oxide semiconductor film 328b.

[0500] By providing the oxide semiconductor film 328a and / or the oxide semiconductor film 328c, the oxide semiconductor film 328b can be distanced from a trap level.

[0501] In addition, sometimes a trap level is farther from a vacuum level than the conduction band bottom level (Ec) of the oxide semiconductor film 328b serving as a channel region, and electrons are easily accumulated in the trap level. When electrons are accumulated in the trap level, the electrons become negative fixed charges, leading to a shift of the threshold voltage of the transistor in the positive direction. Thus, it is preferable that the trap level be closer to the vacuum level than the conduction band bottom level (Ec) of the oxide semiconductor film 328b. By employing the above-described structure, accumulation of electrons in the trap level can be suppressed. As a result, the on-state current and the field-effect mobility of the transistor can be increased.

[0502] The conduction band minimum of the oxide semiconductor film 328a and 328c is closer to the vacuum level than that of the oxide semiconductor film 328b. Typically, the difference between the conduction band minimum of the oxide semiconductor film 328b and that of the oxide semiconductor film 328a and 328c is greater than or equal to 0.15 eV or greater than or equal to 0.5 eV and less than or equal to 2 eV or less than or equal to 1 eV. In other words, the difference between the electron affinity of the oxide semiconductor film 328b and that of the oxide semiconductor film 328a and 328c is greater than or equal to 0.15 eV or greater than or equal to 0.5 eV and less than or equal to 2 eV or less than or equal to 1 eV.

[0503] With the above structure, the oxide semiconductor film 328b serves as a main path of current and functions as a channel region. Further, since the oxide semiconductor film 328a and 328c include one or more of the metal elements included in the oxide semiconductor film 328b which forms the channel region, an interface scattering is less likely to occur at the interface between the oxide semiconductor film 328a and the oxide semiconductor film 328b or at the interface between the oxide semiconductor film 328b and the oxide semiconductor film 328c. Thus, since the movement of carriers is not hindered in the interface, the field-effect mobility of the transistor is improved.

[0504] In order to prevent the oxide semiconductor film 328a and 328c from being used as part of the channel region, a material with low conductivity is used as the oxide semiconductor film 328a and 328c. Alternatively, a material whose electron affinity (difference between the vacuum level and the conduction band minimum) is lower than that of the oxide semiconductor film 328b and whose conduction band minimum is different from (band offset from) that of the oxide semiconductor film 328b is used as the oxide semiconductor film 328a and 328c. Further, in order to suppress the difference between threshold voltages due to the value of the drain voltage, the oxide semiconductor film 328a and 328c are preferably formed using a material whose conduction band minimum is closer to the vacuum level than that of the oxide semiconductor film 328b. For example, the difference between the conduction band minimum of the oxide semiconductor film 328b and that of the oxide semiconductor film 328a and 328c is preferably greater than or equal to 0.2 eV, further preferably greater than or equal to 0.5 eV.

[0505] The oxide semiconductor film 328a and 328c preferably do not include a spinel crystal structure. This is because if the oxide semiconductor film 328a and 328c include a spinel crystal structure, the constituent elements of the conductive film 322a and 322b sometimes diffuse into the oxide semiconductor film 328b at the interface between the spinel crystal structure and another region. Note that the oxide semiconductor film 328a and 328c are preferably CAAC-OS described later, in which case high barrier properties against the constituent elements of the conductive film 322a and 322b, such as copper, can be obtained.

[0506] The thickness of the oxide semiconductor film 328a, 328c is greater than or equal to a thickness at which diffusion of the constituent elements of the conductive film 322a, 322b into the oxide semiconductor film 328b is inhibited and less than a thickness at which supply of oxygen from the insulating film 324 to the oxide semiconductor film 328b is inhibited. For example, when the thickness of the oxide semiconductor film 328a, 328c is 10 nm or more, diffusion of the constituent elements of the conductive film 322a, 322b into the oxide semiconductor film 328b is inhibited. When the thickness of the oxide semiconductor film 328a, 328c is 100 nm or less, oxygen can be efficiently supplied from the insulating film 324 to the oxide semiconductor film 328b.

[0507] When the oxide semiconductor film 328a, 328c is an In-M-Zn oxide (M is Al, Ga, Y, or Sn) in which the atomic ratio of M is higher than that of In, the energy gap of the oxide semiconductor film 328a, 328c can be increased and the electron affinity thereof can be decreased. Thus, the difference in electron affinity between the oxide semiconductor film 328a, 328c and the oxide semiconductor film 328b can be controlled depending on the proportion of the element M. Further, since M is a metal element having a strong bonding force with oxygen, oxygen vacancies are less likely to be generated in the oxide semiconductor layer in which the atomic ratio of the element M is higher than that of In.

[0508] When an In-M-Zn oxide is used as the oxide semiconductor film 328a, 328c, the proportion of In and M other than Zn and O is preferably lower than 50 atomic % for In and higher than 50 atomic % for M, and is more preferably lower than 25 atomic % for In and higher than 75 atomic % for M. Alternatively, a gallium oxide film can be used as the oxide semiconductor film 328a, 328c.

[0509] Further, when the oxide semiconductor films 328a, 328b, 328c are In-M-Zn oxides, the atomic ratio of M in the oxide semiconductor films 328a, 328c is higher than that in the oxide semiconductor film 328b. Typically, the atomic ratio of M in the oxide semiconductor films 328a, 328c is higher than or equal to 1.5 times, preferably higher than or equal to twice, and more preferably higher than or equal to three times the atomic ratio of M in the oxide semiconductor film 328b.

[0510] In addition, when the oxide semiconductor films 328a, 328b, and 328c are In-M-Zn oxides, in the case where the atomic ratio of the oxide semiconductor film 328b is In:M:Zn = x1:y1:z1 and the atomic ratio of the oxide semiconductor films 328a and 328c is In:M:Zn = x2:y2:z2, y2 / x2 is greater than y1 / x1, y2 / x2 is preferably greater than or equal to 1.5 times y1 / x1, y2 / x2 is more preferably greater than or equal to twice y1 / x1, y2 / x2 is further preferably greater than or equal to three times y1 / x1 or greater than or equal to four times y1 / x1. At this time, in the oxide semiconductor film 328b, y1 is preferably greater than or equal to x1, in which case the transistor including the oxide semiconductor film 328b can have stable electrical characteristics. However, in the case where y1 is greater than or equal to three times x1, the field-effect mobility of the transistor including the oxide semiconductor film 328b is decreased. Thus, y1 is preferably less than three times x1.

[0511] In the case where the oxide semiconductor film 328b is an In-M-Zn oxide and the atomic ratio of metal elements of a target used for formation of the oxide semiconductor film 328b is In:M:Zn = x1:y1:z1, x1 / y1 is preferably greater than or equal to 1 / 3 and less than or equal to 6, more preferably greater than or equal to 1 and less than or equal to 6, and z1 / y1 is preferably greater than or equal to 1 / 3 and less than or equal to 6, more preferably greater than or equal to 1 and less than or equal to 6. Note that when z1 / y1 is greater than or equal to 1 and less than or equal to 6, the CAAC-OS described later is easily formed as the oxide semiconductor film 328b. Typical examples of the atomic ratio of metal elements of a target include In:M:Zn = 4:2:4.1, In:M:Zn = 1:1:1.2, and In:M:Zn = 3:1:2.

[0512] In the case where the oxide semiconductor films 328a and 328c are In-M-Zn oxides and the atomic ratio of metal elements of a target used for formation of the oxide semiconductor films 328a and 328c is In:M:Zn = x2:y2:z2, x2 / y2 < x1 / y1 and z2 / y2 is preferably greater than or equal to 1 / 3 and less than or equal to 6, more preferably greater than or equal to 1 and less than or equal to 6. When the atomic ratio of M is higher than that of In, the energy gap of the oxide semiconductor films 328a and 328c can be increased and the electron affinity thereof can be decreased, whereby y2 / x2 is preferably greater than or equal to 3 or greater than or equal to 4. Typical examples of the atomic ratio of metal elements of a target include In:M:Zn = 1:3:2, In:M:Zn = 1:3:4, In:M:Zn = 1:3:5, In:M:Zn = 1:3:6, In:M:Zn = 1:4:2, In:M:Zn = 1:4:4, In:M:Zn = 1:4:5, and In:M:Zn = 1:5:5.

[0513] In addition, in the case where the oxide semiconductor films 328a and 328c are In-M oxides, when M does not contain a divalent metal atom (e.g., zinc) as M, an oxide semiconductor film 328a and 328c which does not have a spinel crystal structure can be formed. As the oxide semiconductor film 328a and 328c, an In-Ga oxide film can be used, for example. This In-Ga oxide film can be formed by a sputtering method using an In-Ga metal oxide target (In:Ga = 7:93), for example. In order to form the oxide semiconductor film 328a and 328c by a sputtering method using DC discharge, when the atomic ratio of In:M is assumed to be x:y, y / (x+y) is preferably 0.96 or lower, more preferably 0.95 or lower, and is for example 0.93.

[0514] In the oxide semiconductor films 328a, 328b, and 328c, the atomic ratio in the above atomic ratio varies within a range of ±40 % as an error.

[0515] In FIG. 36A and FIG. 36B to FIG. 45A the oxide semiconductor film 328 of the transistor Tr2 has a two-layer structure or a three-layer structure, the oxide semiconductor film 308 of the transistor Trl can have the same structure.

[0516] As described above, in the semiconductor device of the present application, the presence or absence of the second gate electrode can be changed, or the stacked structure of the oxide semiconductor film can be changed. The structures of the transistors of this embodiment can be freely combined with each other.

[0517] <3-8. Manufacturing method of semiconductor device>

[0518] Next, a manufacturing method of the semiconductor device 300 of one embodiment of the present application will be described with reference to FIG. 45B and FIG. 36A and FIG. 37A

[0519] Further, FIG. 38A , FIG. 39A , FIG. 40A , FIG. 41A , FIG. 42A , FIG. 43A , FIG. 44A , FIG. 45A , FIG. 36B and FIG. 37B are cross-sectional views illustrating the manufacturing method of the semiconductor device 300, FIG. 38B , FIG. 39B , FIG. 40B , FIG. 41B , FIG. 42B , FIG. 43B , FIG. 44B , FIG. 45B ,​FIG. 36A and FIG. 36B is a cross-sectional view illustrating a method for manufacturing the semiconductor device 300.

[0520] First, the insulating film 306 is formed over the substrate 302, and an oxide semiconductor film is formed over the insulating film 306. Then, the oxide semiconductor film is processed into an island shape, whereby the oxide semiconductor film 308 is formed (see FIG. 37A and FIG. 37B ).

[0521] In this embodiment mode, a glass substrate can be used as the substrate 302.

[0522] The insulating film 306 can be formed by a sputtering method, a CVD method, an evaporation method, a pulse laser deposition (PLD) method, a printing method, or a coating method, as appropriate. In this embodiment mode, a silicon nitride film with a thickness of 400 nm and a silicon oxynitride film with a thickness of 50 nm are formed as the insulating film 306 by using a PECVD apparatus.

[0523] After the insulating film 306 is formed, oxygen can be added to the insulating film 306. As the oxygen to be added to the insulating film 306, an oxygen radical, an oxygen atom, an oxygen atom ion, an oxygen molecule ion, or the like can be used. At the time of adding oxygen, an ion doping method, an ion implantation method, plasma treatment, or the like can be used. Alternatively, a film for suppressing the release of oxygen can be formed over the insulating film 306, and then oxygen can be added to the insulating film 306 through the film.

[0524] The film for suppressing the release of oxygen can be formed using a conductive material selected from a metal element of indium, zinc, gallium, tin, aluminum, chromium, tantalum, titanium, molybdenum, nickel, iron, cobalt, tungsten; an alloy containing the above metal element as a component; an alloy containing a combination of the above metal elements; a metal nitride containing the above metal element; a metal oxide containing the above metal element; a metal oxynitride containing the above metal element; or the like.

[0525] When oxygen is added by plasma treatment and high-density oxygen plasma is generated by excitation of oxygen with microwaves, the amount of oxygen added to the insulating film 306 can be increased.

[0526] The oxide semiconductor film 308 can be formed by a sputtering method, a coating method, a pulse laser evaporation method, a laser ablation method, a thermal CVD method, or the like. The oxide semiconductor film can be processed into the oxide semiconductor film 308 by forming a mask over the oxide semiconductor film by a photolithography process and then etching a part of the oxide semiconductor film using the mask. Alternatively, the oxide semiconductor film 308 can be formed directly over the insulating film 306 in isolation from one another by a printing method.

[0527] In the case where the oxide semiconductor film is formed by a sputtering method, an RF power source device, an AC power source device, a DC power source device, or the like can be appropriately used as a power source device for generating plasma. As a sputtering gas for forming the oxide semiconductor film, a rare gas (typically, argon), oxygen, or a mixed gas of a rare gas and oxygen can be appropriately used. In the mixed gas of a rare gas and oxygen, the proportion of oxygen to the rare gas is preferably increased.

[0528] To improve the crystallinity of the oxide semiconductor film formed by a sputtering method, for example, the oxide semiconductor film is preferably formed at a substrate temperature higher than or equal to 150 °C and lower than or equal to 750 °C, higher than or equal to 150 °C and lower than or equal to 450 °C, or higher than or equal to 200 °C and lower than or equal to 350 °C.

[0529] In this embodiment, as the oxide semiconductor film 308, an oxide semiconductor film having a thickness of 40 nm is formed using an In-Ga-Zn metal oxide (In:Ga:Zn = 4:2:4.1 [atomic ratio]) as a sputtering target by a sputtering apparatus.

[0530] After the oxide semiconductor film 308 is formed, the oxide semiconductor film 308 can be dehydrogenated or dehydrated by heat treatment. The temperature of the heat treatment is typically higher than or equal to 150 °C and lower than the strain point of the substrate, higher than or equal to 250 °C and lower than or equal to 450 °C, or higher than or equal to 300 °C and lower than or equal to 450 °C.

[0531] The heat treatment can be performed in an inert gas atmosphere containing a rare gas such as helium, neon, argon, xenon, or krypton, or an inert gas atmosphere containing nitrogen. Alternatively, the heat treatment can be performed in an inert gas atmosphere and then in an oxygen atmosphere. The above-described inert gas atmosphere and oxygen atmosphere each preferably do not contain hydrogen, water, or the like. The treatment time can be longer than or equal to 3 minutes and shorter than or equal to 24 hours.

[0532] An electric furnace, an RTA apparatus, or the like can be used for the heat treatment. With the use of the RTA apparatus, heat treatment at a temperature higher than or equal to the strain point of the substrate can be performed in a short time. Thus, the heat treatment time can be shortened.

[0533] The oxide semiconductor film is formed while being heated or after the oxide semiconductor film is formed, whereby the hydrogen concentration in the oxide semiconductor film measured by secondary ion mass spectrometry can be 5 x 10 19 atoms / cm 3 Hereinafter, 1 x 10 19 atoms / cm 3 Hereinafter, 5 x 10 18 atoms / cm 3 Hereinafter, 1 x 10 18 atoms / cm 3Hereinafter, 5 x 10 17 atoms / cm 3 Hereinafter, 1 x 10 16 atoms / cm 3 Hereinafter.

[0534] Next, an insulating film and a conductive film are formed over the insulating film 306 and the oxide semiconductor film 308, and processed into an island shape, whereby an insulating film 310 and a conductive film 320 are formed (see FIG 18B). FIG. 38A and FIG. 38B

[0535] As the insulating film 310, a silicon oxide film or a silicon oxynitride film can be formed by a PECVD method. At this time, as the source gas, a deposition gas containing silicon and an oxidizing gas are preferably used. Typical examples of the deposition gas containing silicon are silane, disilane, trisilane, and fluorosilane. Examples of the oxidizing gas are oxygen, ozone, dinitrogen monoxide, and nitrogen dioxide.

[0536] As the insulating film 310, a silicon oxynitride film with a small number of defects can be formed by a PECVD method under the following conditions: the flow rate of the oxidizing gas is greater than 20 times and less than 100 times or more than 40 times and less than 80 times the flow rate of the deposition gas; the pressure in the treatment chamber is lower than 100 Pa or lower than or equal to 50 Pa.

[0537] As the insulating film 310, a dense silicon oxide film or a dense silicon oxynitride film can be formed under the following conditions: the substrate provided in the treatment chamber of the PECVD apparatus is held at a temperature higher than or equal to 280 °C and lower than or equal to 400 °C, the source gas is introduced into the treatment chamber to set the pressure in the treatment chamber to be higher than or equal to 20 Pa and lower than or equal to 250 Pa, preferably higher than or equal to 100 Pa and lower than or equal to 250 Pa, and high-frequency power is supplied to the electrode provided in the treatment chamber.

[0538] The insulating film 310 can be formed by a plasma CVD method using microwaves. Microwave refers to a wave in a frequency range of 300 MHz to 300 GHz. In a microwave, the electron temperature is low and the energy of an electron is small. Furthermore, in supplied electric power, the proportion of electric power used for acceleration of an electron is small, whereby the electric power can be used for dissociation and ionization of more molecules. Thus, a high-density plasma (high-density plasma) can be excited. Accordingly, damage to a formation surface and a deposit caused by plasma is small, and an insulating film 310 with a small number of defects can be formed.

[0539] ​Alternatively, the insulating film 310 can be formed by a CVD method using an organic silane gas. As the organic silane gas, a silicon compound such as tetraethyl orthosilicate (TEOS) (chemical formula: Si(OC2H5)4), tetramethylsilane (TMS) (chemical formula: Si(CH3)4), tetramethylcyclotetrasiloxane (TMCTS), octamethylcyclotetrasiloxane (OMCTS), hexamethyldisilazane (HMDS), triethoxysilane (SiH(OC2H5)3), tris(dimethylamino)silane (SiH(N(CH3)2)3), or the like can be used. By using the CVD method using an organic silane gas, an insulating film 310 with high coverage can be formed.

[0540] In this embodiment, as the insulating film 310, a silicon oxynitride film with a thickness of 150 nm is formed using a PECVD apparatus.

[0541] The conductive film 320 is preferably formed using an oxide conductor (OC). At the time of formation of the conductive film 320, oxygen is added to the insulating film 310 from the conductive film 320.

[0542] The conductive film 320 is preferably formed by a sputtering method in an atmosphere containing an oxygen gas. By forming the conductive film 320 in an atmosphere containing an oxygen gas, oxygen can be efficiently added to the insulating film 310.

[0543] Further, the conductive film 320 can be formed using the same material as that of the oxide semiconductor film 308.

[0544] In this embodiment, as the conductive film 320, a conductive film with a thickness of 20 nm is formed using a sputtering apparatus, and an In-Ga-Zn metal oxide (In:Ga:Zn = 5:1:7 [atomic percentage]) is used as a sputtering target.

[0545] In this embodiment, the conductive film 320 and the insulating film 310 are processed by a dry etching method.

[0546] At the time of processing of the conductive film 320 and the insulating film 310, the thickness of a region of the oxide semiconductor film 308 which does not overlap with the conductive film 320 is sometimes reduced.

[0547] Next, an impurity element is added from the insulating film 306, the oxide semiconductor film 308, and the conductive film 320.

[0548] At the time of addition of the impurity element, an ion doping method, an ion implantation method, a plasma treatment method, or the like can be used. In the case of using a plasma treatment method, a plasma generated in a gas atmosphere containing an impurity element can be used to add the impurity element. A dry etching apparatus, an ashing apparatus, a plasma CVD apparatus, a high-density plasma CVD apparatus, or the like can be used to generate the plasma.

[0549] As the source gas of the impurity element, at least one of B2H6, PH3, CH4, N2, NH3, AlH3, AlCl3, SiH4, Si2H6, F2, HF, H2, and a rare gas can be used. Alternatively, at least one of B2H6, PH3, N2, NH3, AlH3, AlCl3, F2, HF, and H2diluted with a rare gas can be used. By using at least one of B2H6, PH3, N2, NH3, AlH3, AlCl3, F2, HF, and H2diluted with a rare gas, at least one of a rare gas, hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, and chlorine can be added to the oxide semiconductor film 308 and the conductive film 320.

[0550] Alternatively, at least one of B2H6, PH3, CH4, N2, NH3, AlH3, AlCl3, SiH4, Si2H6, F2, HF, and H2may be added to the oxide semiconductor film 308 and the conductive film 320 after a rare gas is added to the oxide semiconductor film 308 and the conductive film 320.

[0551] Alternatively, a rare gas can be added to the oxide semiconductor film 308 and the conductive film 320 after at least one of B2H6, PH3, CH4, N2, NH3, AlH3, AlCl3, SiH4, Si2H6, F2, HF, and H2is added to the oxide semiconductor film 308 and the conductive film 320.

[0552] The addition of the impurity element can be controlled by appropriately setting the conditions for implantation such as an acceleration voltage and a dose. For example, in the case of adding argon by an ion implantation method, the acceleration voltage can be higher than or equal to 10 kV and lower than or equal to 100 kV, and the dose can be higher than or equal to 1 x 1011ions / cm2and lower than or equal to 1 x 1014ions / cm2. 13 ions / cm2 2 The acceleration voltage can be higher than or equal to 10 kV and lower than or equal to 100 kV, and the dose can be higher than or equal to 1 x 1011ions / cm2and lower than or equal to 1 x 1014ions / cm2. 16 ions / cm2 2 The acceleration voltage can be higher than or equal to 10 kV and lower than or equal to 100 kV, and the dose can be higher than or equal to 1 x 1011ions / cm2and lower than or equal to 1 x 1014ions / cm2. 14 ions / cm2 2 The acceleration voltage can be higher than or equal to 10 kV and lower than or equal to 100 kV, and the dose can be higher than or equal to 1 x 1011ions / cm2and lower than or equal to 1 x 1014ions / cm2. 13 ions / cm2 2 The acceleration voltage can be higher than or equal to 10 kV and lower than or equal to 100 kV, and the dose can be higher than or equal to 1 x 1011ions / cm2and lower than or equal to 1 x 1014ions / cm2. 16 ions / cm2 2 The acceleration voltage can be higher than or equal to 10 kV and lower than or equal to 100 kV, and the dose can be higher than or equal to 1 x 1011ions / cm2and lower than or equal to 1 x 1014ions / cm2. 15 ions / cm2 2 .

[0553] In this embodiment, the oxide semiconductor film 308 and the conductive film 320 are doped with argon as an impurity element by using a doping apparatus. Note that this embodiment is not limited to the above example in which argon is added as an impurity element, and for example, nitrogen can be added, or the process of adding an impurity element can not be performed.

[0554] Next, the insulating film 314 is formed over the insulating film 306, the oxide semiconductor film 308, and the conductive film 320. By forming the insulating film 314, the oxide semiconductor film 308 is in contact with the insulating film 314 and is used as the source region 308s and the drain region 308d. The oxide semiconductor film 308 which is not in contact with the insulating film 314, that is, the oxide semiconductor film 308 which is in contact with the insulating film 310 is used as the channel region 308i. Thus, the oxide semiconductor film 308 including the channel region 308i, the source region 308s, and the drain region 308d is formed (see FIG. 3B). FIG. 38A and FIG. 38B ).

[0555] The insulating film 314 can be formed using a material that can be used for the insulating film 314. In this embodiment, as the insulating film 314, a silicon nitride film with a thickness of 100 nm is formed by a PECVD apparatus.

[0556] By using the silicon nitride film as the insulating film 314, hydrogen and / or nitrogen in the silicon nitride film enters the conductive film 320, the source region 308s, and the drain region 308d which are in contact with the insulating film 314, and thus the carrier density of the conductive film 320, the source region 308s, and the drain region 308d can be increased.

[0557] Next, the insulating film 316 is formed over the insulating film 314.

[0558] The insulating film 316 can be formed using a material that can be used for the insulating film 316. In this embodiment, as the insulating film 316, a silicon oxynitride film with a thickness of 300 nm is formed by a PECVD apparatus.

[0559] Next, a mask is formed at a desired position over the insulating film 316 by a photolithography process, and then a part of the insulating film 316 and the insulating film 314 is etched, whereby an opening 341a reaching the source region 308s and an opening 341b reaching the drain region 308d are formed (see FIG. 3C). FIG. 38A and FIG. 38B ).

[0560] As a method for etching the insulating film 316 and the insulating film 314, a wet etching method and / or a dry etching method can be appropriately used. In this embodiment, the insulating film 316 and the insulating film 314 are processed by a dry etching method.

[0561] Next, a conductive film is formed over the insulating film 316 in a manner of filling the openings 341a and 341b, and a mask is formed at a desired position by a photolithography process. Then, a part of the conductive film is etched, whereby the conductive films 312a and 312b are formed (see FIG. 3C). FIG. 39A and FIG. 39B ).

[0562] The conductive films 312a and 312b can be formed using a material that can be used for the conductive films 312a and 312b. In this embodiment, as the conductive films 312a and 312b, a titanium film with a thickness of 50 nm, an aluminum film with a thickness of 400 nm, and a titanium film with a thickness of 100 nm are formed in that order by a sputtering apparatus.

[0563] As a method for processing the conductive films 312a and 312b, a wet etching method and / or a dry etching method can be appropriately used. In this embodiment, the conductive films 312 are processed into the conductive films 312a and 312b by a dry etching method.

[0564] Through the above steps, the transistor Trl can be manufactured.

[0565] In addition, a film or a layer included in the transistor Trl (e.g., an insulating film, an oxide semiconductor film, a conductive film) can be formed by a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, or an ALD (atomic layer deposition) method. Alternatively, a coating method or a printing method can be used. Although a sputtering method or a plasma-enhanced chemical vapor deposition (PECVD) method is a typical example of a film formation method, a thermal CVD method can be used. As an example of the thermal CVD method, an MOCVD (metalorganic chemical vapor deposition) method can be given.

[0566] Film formation by a thermal CVD method can be performed in such a manner that a source gas and an oxidizer are simultaneously supplied into a processing chamber whose pressure is set to be atmospheric pressure or reduced pressure, and the source gas and the oxidizer are made to react with each other in the vicinity of or on a substrate. In film formation by a thermal CVD method, plasma is not generated, and thus there is an advantage that defects due to plasma damage are not generated.

[0567] The film formation using the ALD method can be performed in the following manner: the source gas for the reaction is introduced into a processing chamber whose pressure is set to be atmospheric pressure or reduced pressure, and a reaction is caused, and then the processing is repeated in this order. An inert gas (e.g., argon or nitrogen) can also be introduced as a carrier gas together with the source gas. For example, two or more kinds of source gases can be sequentially supplied into the processing chamber. At this time, between the reaction of the first source gas and the introduction of the second source gas, an inert gas is introduced to prevent mixing of the source gases. Alternatively, the first source gas can be exhausted by vacuum exhaust instead of the introduction of the inert gas, and then the second source gas is introduced. The first source gas is attached to the surface of the substrate and reacts to form a first layer, and then the second source gas introduced thereafter is attached and reacts to form a second layer on the first layer, whereby a thin film is formed. By repeatedly introducing the gases in this order a plurality of times until a desired thickness is obtained, a thin film with good step coverage can be formed. The thickness of the thin film can be accurately adjusted depending on the number of times of repeating the introduction of the gases, and thus the ALD method is suitable for the manufacture of micro FETs.

[0568] Various films such as the conductive film, the insulating film, the oxide semiconductor film, and the metal oxide film described above can be formed by a thermal CVD method such as an MOCVD method. For example, when an In-Ga-Zn-O film is formed, trimethyl indium (In(CH3)3), trimethyl gallium (Ga(CH3)3), and dimethyl zinc (Zn(CH3)2) are used. Instead of trimethyl gallium, triethyl gallium (Ga(C2H5)3) can be used, and instead of dimethyl zinc, diethyl zinc (Zn(C2H5)2) can be used, without being limited to the above combinations.

[0569] For example, when a hafnium oxide film is formed by using a film formation apparatus using the ALD method, the following two kinds of gases are used: ozone (O3) which is used as an oxidizing agent; and a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor (hafnium alcoholate, tetrakisdimethylamido hafnium (TDMAH, Hf[N(CH3)2]4), or tetrakis(ethylmethylamido)hafnium).

[0570] For example, when an aluminum oxide film is formed by using a film formation apparatus using the ALD method, the following two kinds of gases are used: H2O which is used as an oxidizing agent; and a source gas obtained by vaporizing a liquid containing a solvent and an aluminum precursor (e.g., trimethyl aluminum (TMA, Al(CH3)3)). As other examples of materials, there are tri(dimethylamide)aluminum, triisobutylaluminum, aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedione).

[0571] For example, when a silicon oxide film is formed by using a film formation apparatus using the ALD method, hexachlorodisilane is attached to a film formation surface, and radicals of an oxidizing gas (O2, nitrous oxide) are supplied to react with the attached material.

[0572] For example, in the case of forming a tungsten film by using a film formation apparatus using an ALD method, WF6gas and B2H6gas are introduced in this order to form an initial tungsten film, and then WF6gas and H2gas are used to form a tungsten film. Note that SiH4gas can be used instead of B2H6gas.

[0573] For example, in the case of forming an oxide semiconductor film such as an In-Ga-Zn-O film by using a film formation apparatus using an ALD method, an In-O layer is formed using In(CH3)3gas and O3gas, a Ga-O layer is formed using Ga(CH3)3gas and O3gas, and then a Zn-O layer is formed using Zn(CH3)2gas and O3gas. Note that the order of these layers is not limited to the above example. Further, these gases can be used to form a mixed compound layer such as an In-Ga-O layer, an In-Zn-O layer, a Ga-Zn-O layer, or the like. Although H2O gas obtained by bubbling an inert gas such as Ar can be used instead of O3gas, O3gas which does not contain H is preferably used.

[0574] Next, an insulating film 318 is formed over the insulating film 316 and the conductive films 312a and 312b.

[0575] The insulating film 318 can be formed by a sputtering method, a CVD method, an evaporation method, a pulse laser deposition (PLD) method, a printing method, or a coating method, as appropriate. In this embodiment, a silicon nitride film with a thickness of 400 nm and a silicon oxynitride film with a thickness of 50 nm are formed as the insulating film 318 by using a PECVD apparatus.

[0576] After the insulating film 318 is formed, oxygen can be added to the insulating film 318. Examples of the oxygen added to the insulating film 318 include an oxygen radical, an oxygen atom, an oxygen atom ion, an oxygen molecule ion, and the like. In the case where oxygen is added, an ion doping method, an ion implantation method, plasma treatment, or the like can be used. Alternatively, a film for suppressing separation of oxygen can be formed over the insulating film, and then oxygen can be added to the insulating film 318 through the film.

[0577] The film for suppressing separation of oxygen can be formed using a conductive material selected from metal elements such as indium, zinc, gallium, tin, aluminum, chromium, tantalum, titanium, molybdenum, nickel, iron, cobalt, tungsten; an alloy containing any of the above metal elements as a component; an alloy containing a combination of any of the above metal elements; a metal nitride containing any of the above metal elements; a metal oxide containing any of the above metal elements; a metal oxynitride containing any of the above metal elements; and the like.

[0578] When oxygen is added by plasma treatment and high-density oxygen plasma is generated by excitation of oxygen with microwaves, the amount of oxygen added to the insulating film 318 can be increased.

[0579] Further, the insulating film 318 can have a stacked structure of silicon nitride films. Specifically, the silicon nitride film can have a three-layer structure of a first silicon nitride film, a second silicon nitride film, and a third silicon nitride film. Examples of the three-layer structure are as follows.

[0580] For example, the first silicon nitride film with a thickness of 50 nm can be formed under conditions where silane with a flow rate of 200 sccm, nitrogen with a flow rate of 2000 sccm, and ammonia gas with a flow rate of 100 sccm are supplied to a reaction chamber of a PECVD apparatus as source gases, the pressure in the reaction chamber is controlled to be 100 Pa, and a power of 2000 W is supplied using a high-frequency power supply of 27.12 MHz.

[0581] The second silicon nitride film with a thickness of 300 nm can be formed under conditions where silane with a flow rate of 200 sccm, nitrogen with a flow rate of 2000 sccm, and ammonia gas with a flow rate of 2000 sccm are supplied to a reaction chamber of a PECVD apparatus as source gases, the pressure in the reaction chamber is controlled to be 100 Pa, and a power of 2000 W is supplied using a high-frequency power supply of 27.12 MHz.

[0582] The third silicon nitride film with a thickness of 50 nm can be formed under conditions where silane with a flow rate of 200 sccm and nitrogen with a flow rate of 5000 sccm are supplied to a reaction chamber of a PECVD apparatus as source gases, the pressure in the reaction chamber is controlled to be 100 Pa, and a power of 2000 W is supplied using a high-frequency power supply of 27.12 MHz.

[0583] Further, the first silicon nitride film, the second silicon nitride film, and the third silicon nitride film can be formed at a substrate temperature of 350 °C or lower.

[0584] When the insulating film 318 has the three-layer structure of silicon nitride films, the following effects can be obtained, for example, in the case where a conductive film containing copper (Cu) is used as the conductive films 312a and 312b.

[0585] The first silicon nitride film can suppress diffusion of copper (Cu) elements from the conductive films 312a and 312b. The second silicon nitride film has a function of releasing hydrogen and can increase the withstand voltage of the insulating film used as a gate insulating film. The third silicon nitride film is a film with a small amount of released hydrogen and can suppress diffusion of hydrogen released from the second silicon nitride film.

[0586] Next, an oxide semiconductor film 328 is formed over the insulating film 318 (see FIG. 40A and FIG. 40B ).

[0587] In this embodiment, an oxide semiconductor film is formed by a sputtering method using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). The substrate temperature at the time of formation of the oxide semiconductor film is 170 °C. As a deposition gas at the time of formation of the oxide semiconductor film, an oxygen gas with a flow rate of 60 seem and an argon gas with a flow rate of 140 seem are used. Then, the oxide semiconductor film is processed into a desired shape, whereby an island-shaped oxide semiconductor film 328 is formed. Note that a wet etching apparatus is used at the time of formation of the oxide semiconductor film.

[0588] Next, a conductive film is formed over the insulating film 318 and the oxide semiconductor film 328, and is processed into a desired shape, whereby conductive films 322a and 322b are formed. Then, insulating films 324 and 326 are formed over the insulating film 318, the oxide semiconductor film 328, and the conductive films 322a and 322b (see FIG. 1C). FIG. 41A and FIG. 41B ).

[0589] In this embodiment, as the conductive films 322a and 322b, a stacked film in which an aluminum film with a thickness of 100 nm and a titanium film with a thickness of 50 nm are sequentially stacked is formed by a sputtering method.

[0590] After the formation of the conductive films 322a and 322b, the surface (the back channel side) of the oxide semiconductor film 328 can be washed. The washing can be performed with an etchant such as phosphoric acid aqueous solution. By the washing, impurities (e.g., elements included in the conductive films 322a and 322b) attached to the surface of the oxide semiconductor film 328 can be removed. Note that the washing is not necessarily performed, and can not be performed depending on circumstances.

[0591] In the formation of the conductive films 322a and 322b and / or the above washing process, the thickness of the region of the oxide semiconductor film 328 which is not covered with the conductive films 322a and 322b is sometimes thinned.

[0592] In this embodiment, as the insulating film 324 and the insulating film 326, a silicon oxynitride film with a thickness of 20 nm and a silicon oxynitride film with a thickness of 200 nm are formed by a PECVD method, respectively.

[0593] It is preferable that the insulating film 326 be formed continuously without exposure to the atmosphere after the insulating film 324 is formed. The insulating film 326 is formed continuously without exposure to the atmosphere after the insulating film 324 is formed, with at least one of the flow rate of the source gas, the pressure, the high-frequency power, and the substrate temperature adjusted, whereby the concentration of impurities derived from the atmospheric components at the interface of the insulating film 324 and the insulating film 326 can be reduced, and oxygen in the insulating films 324 and 326 can be moved into the oxide semiconductor film 328, so that the amount of oxygen vacancies in the oxide semiconductor film 328 can be reduced.

[0594] In this embodiment, as the insulating film 324, a silicon oxynitride film is formed by a PECVD method under conditions where the temperature of the substrate 302 is kept at 220 °C, silane with a flow rate of 50 sccm and dinitrogen monoxide with a flow rate of 2000 sccm are used as the source gas, the pressure in the treatment chamber is 20 Pa, and a high-frequency power of 100 W (power density: 1.6 x 10 -2 W / cm 2 ) is supplied to the parallel plate electrodes at a frequency of 13.56 MHz.

[0595] As the insulating film 326, a silicon oxide film or a silicon oxynitride film is formed under conditions where the temperature of a substrate provided in a treatment chamber of a PECVD device which is vacuum-pumped is kept at 180 °C to 350 °C, a source gas is introduced into the treatment chamber, the pressure in the treatment chamber is set to 100 Pa to 250 Pa, preferably 100 Pa to 200 Pa, and a high-frequency power of 0.17 W / cm 2 2and 0.5 W / cm 2 2, preferably 0.25 W / cm 2 2and 0.35 W / cm 2 2or lower is supplied to an electrode provided in the treatment chamber.

[0596] As the film formation conditions of the insulating film 326, a high-frequency power with the above-described power density is supplied to a reaction chamber having the above-described pressure, whereby the decomposition efficiency of the source gas in plasma is increased, the oxygen radicals are increased, and oxidation of the source gas is promoted, and thus the oxygen content in the insulating film 326 exceeds the stoichiometric composition. In a film formed at a substrate temperature in the above-described temperature range, the bonding force between silicon and oxygen is weak, and thus a part of the oxygen in the film is released by heat treatment in a later step. Thus, an oxide insulating film whose oxygen content exceeds the stoichiometric composition and which releases a part of the oxygen by heat can be formed.

[0597] In addition, in the formation of the insulating film 326, the insulating film 324 is used as a protective film for the oxide semiconductor film 328. Thus, the insulating film 326 can be formed using high-frequency power with high power density while reducing damage to the oxide semiconductor film 328.

[0598] In addition, in the film formation conditions of the insulating film 326, the amount of defects in the insulating film 326 can be reduced by increasing the flow rate of the deposition gas containing silicon with respect to the oxidizing gas. Typically, an oxide insulating film with a low amount of defects can be formed, in which the spin density of a signal attributed to a silicon dangling bond and appearing at g = 2.001 measured by ESR is lower than 6 x 1017 spins / cm 17 spins / cm 3 , preferably, 3 x 1017 spins / cm 17 spins / cm 3 , more preferably, 1.5 x 1017 spins / cm 17 spins / cm 3 or lower. As a result, the reliability of the transistor Tr2 can be improved.

[0599] It is preferable to perform a heat treatment (hereinafter referred to as a first heat treatment) after the formation of the insulating films 324 and 326. By the first heat treatment, the oxynitride contained in the insulating films 324 and 326 can be reduced. By the first heat treatment, a part of oxygen contained in the insulating films 324 and 326 can be moved to the oxide semiconductor film 328, so that the amount of oxygen vacancies in the oxide semiconductor film 328 can be reduced.

[0600] The temperature of the first heat treatment is typically lower than 400 °C, preferably lower than 375 °C, further preferably higher than or equal to 150 °C and lower than or equal to 350 °C. The first heat treatment can be performed in an atmosphere of nitrogen, oxygen, ultra-dry air (air whose water content is 20 ppm or lower, preferably 1 ppm or lower, preferably 10 ppb or lower), or a rare gas (e.g., argon, helium). In that case, it is preferable that hydrogen, water, or the like be not contained in the above-described nitrogen, oxygen, ultra-dry air, or rare gas. An electric furnace, an RTA (rapid thermal anneal) apparatus, or the like can be used for the heat treatment.

[0601] Next, an opening 382 reaching the conductive film 322a is formed in a desired region of the insulating films 324 and 326. Then, a conductive film 330 is formed over the insulating film 326 and the conductive film 322a (see FIG. 42A and FIG. 42B ).

[0602] When forming the opening 382, a dry etching apparatus or a wet etching apparatus can be used. An ITSO film (In2O3: SnO2: SiO2= 85: 10: 5 [wt%]) having a thickness of 100 nm is formed and processed into an island shape, thereby obtaining the conductive film 330.

[0603] The transistor Tr2 can be manufactured by the above process.

[0604] Next, a stack film of an insulating film which becomes the insulating films 334 and 336 is formed over the insulating film 326 and the conductive film 330. Then, an opening 384 reaching the conductive film 330 is formed in a desired region of the stack film (see FIG. 43A and FIG. 43B ).

[0605] As the insulating film 334, a silicon oxynitride film having a thickness of 200 nm is formed by a PECVD method. As the insulating film 336, a photosensitive acrylic resin film having a thickness of 1.5 μm is formed.

[0606] When forming the opening 384, a dry etching apparatus or a wet etching apparatus is used.

[0607] Next, a conductive film is formed over the insulating film 336 and the conductive film 330 and processed into an island shape, thereby forming a conductive film 338 (see FIG. 44A and FIG. 44B ).

[0608] As the conductive film 338 in this embodiment, a stack film of an ITSO film having a thickness of 10 nm, a reflective metal film (here, a metal film containing silver, palladium, and copper) having a thickness of 200 nm, and an ITSO film having a thickness of 10 nm is used. The stack film is processed into the conductive film 338 using a wet etching apparatus.

[0609] Next, an island-shaped insulating film 340 is formed over the insulating film 336 and the conductive film 338 (see FIG. 30A and FIG. 30B ).

[0610] As the insulating film 340, a photosensitive polyimide film having a thickness of 1.5 μm is used.

[0611] Next, an EL layer 342 is formed over the conductive film 338, and then a conductive film 344 is formed over the insulating film 340 and the EL layer 342, thereby obtaining a light emitting element 360.

[0612] Note that the method for manufacturing the light emitting element 360 will be described in detail in Embodiment Mode 5.

[0613] The light emitting element 360 can be manufactured by the above manufacturing process. FIG. 46Aand FIG. 46B to FIG. 53A The semiconductor device 300 shown.

[0614] The structures and methods shown in this embodiment can be appropriately combined with the structures and methods shown in other embodiments.

[0615] Implementation Method 4

[0616] In this embodiment, refer to FIG. 53B and FIG. 46A and FIG. 46B A semiconductor device and a method for manufacturing a semiconductor device according to one aspect of the present invention will be described.

[0617] <4-1. Example 1 of the structure of a semiconductor device>

[0618] FIG. 46A This is a top view of a semiconductor device 400 according to one aspect of the present invention. FIG. 46B It is along FIG. 46A The cross-sectional view of the dashed-dot line A1-A2 in the diagram. Furthermore, FIG. 46B This includes the cross-section of transistor Tr1 along the channel length (L) and the cross-section of transistor Tr2 along the channel length (L).

[0619] FIG. 46A and FIG. 46B The semiconductor device 400 shown includes: transistor Tr1; and transistor Tr2, at least a portion of which overlaps with transistor Tr1. Furthermore, transistors Tr1 and Tr2 are top-gate transistors.

[0620] Since transistor Tr1 overlaps at least partially with transistor Tr2, the area of ​​the transistor can be reduced.

[0621] Transistor Tr1 includes: an insulating film 306 on substrate 302; an oxide semiconductor film 308 on insulating film 306; an insulating film 310 on oxide semiconductor film 308; a conductive film 320 on insulating film 310; and an insulating film 314 on insulating film 306, oxide semiconductor film 308, and conductive film 320. Similar to Embodiment 3, oxide semiconductor film 308 includes a channel region 308i overlapping with conductive film 320 and contacting insulating film 310, a source region 308s contacting insulating film 314, and a drain region 308d contacting insulating film 314.

[0622] Further, the transistor Tr1 includes an insulating film 316 over the insulating film 314, a conductive film 312a electrically connected to the oxide semiconductor film 308 in an opening 341a formed in the insulating film 314 and the insulating film 316, a conductive film 312b electrically connected to the oxide semiconductor film 308 in an opening 341b formed in the insulating film 314 and the insulating film 316, and an insulating film 318 over the insulating film 316, the conductive film 312a, and the conductive film 312b.

[0623] The transistor Tr2 includes the conductive film 312b, the insulating film 318 over the conductive film 312b, the oxide semiconductor film 408 over the insulating film 318, the insulating film 410b over the oxide semiconductor film 408, the conductive film 412b over the insulating film 410b, and the insulating film 414 over the oxide semiconductor film 408 and the conductive film 412b. Like the oxide semiconductor film 308, the oxide semiconductor film 408 includes a channel region 408i which overlaps with the conductive film 412b and is in contact with the insulating film 410b, a source region 408s which is in contact with the insulating film 414, and a drain region 408d which is in contact with the insulating film 414.

[0624] Further, the transistor Tr2 includes an insulating film 416 over the insulating film 414, a conductive film 418a provided over the insulating film 416 and electrically connected to the oxide semiconductor film 408, and a conductive film 418b provided over the insulating film 416 and electrically connected to the oxide semiconductor film 408.

[0625] Further, as illustrated in FIGS. 3A and 3B, the oxide semiconductor film 308 and the oxide semiconductor film 408 partially overlap with each other. FIG. 46A and FIG. 46B

[0626] The oxide semiconductor film 308 can have the same structure as that of the structure illustrated in Embodiment 3. The oxide semiconductor film 408 can have the same structure as that of the oxide semiconductor film 328 illustrated in Embodiment 3.

[0627] Accordingly, one or both of the field-effect mobility of the transistor Tr1 and the field-effect mobility of the transistor Tr2 can exceed 10 cm 2 / Vs, preferably, 30 cm 2 / Vs.

[0628] ​For example, when the transistor with high field-effect mobility described above is used for a gate driver which generates a gate signal of a display device, the display device can have a narrow frame. When the transistor with high field-effect mobility described above is used for a source driver included in a display device which supplies a signal from a signal line (particularly, a demultiplexer connected to an output terminal of a shift register included in the source driver), the number of wirings connected to the display device can be reduced. Further, when the transistor with high field-effect mobility described above is used for one or both of a selection transistor and a driver transistor of a pixel circuit included in a display device, the display quality of the display device can be improved.

[0629] FIG. 46A and FIG. 46B The semiconductor device 400 illustrated in FIGS. 1A and 1B can be appropriately used for a pixel circuit of a display device. FIG. 46A and FIG. 46B With the layout illustrated in FIGS. 2A and 2B, the pixel density of a display device can be increased. For example, even when the pixel density of a display device exceeds 1000 ppi or 2000 ppi, the pixel density can be increased by the layout illustrated in FIGS. 2A and 2B. FIG. 31 and FIG. 46A With the layout illustrated in FIGS. 3A and 3B, the aperture ratio of a pixel can be increased. Here, ppi is a unit representing the number of pixels per inch.

[0630] Further, in the case where the semiconductor device 400 illustrated in FIGS. 4A and 4B is used for a pixel circuit of a display device, the same structure as a pixel circuit as illustrated in FIGS. 5A and 5B can be used. FIG. 46B and FIG. 46A Further, in the case where the semiconductor device 400 illustrated in FIGS. 4A and 4B is used for a pixel circuit of a display device, the same structure as a pixel circuit as illustrated in FIGS. 5A and 5B can be used. FIG. 46B

[0631] In the case where the semiconductor device 400 illustrated in FIGS. 6A and 6B is used for a pixel of a display device, the channel length (L) and the channel width (W) of a transistor and the line width of a wiring and an electrode connected to the transistor, and the like can be made large, for example. FIG. 46A and FIG. 46B When at least part of the transistor Tr1 and the transistor Tr2 is arranged to overlap as illustrated in FIGS. 7A and 7B, the line width and the like can be increased as compared to the case where the transistor Tr1 and the transistor Tr2 are provided on the same plane, so that unevenness in processing dimensions can be reduced. FIG. 47A and FIG. 47B to FIG. 53A Further, one or both of a conductive film and an insulating film can be commonly used between the transistor Tr1 and the transistor Tr2, so that the number of masks or the number of steps can be reduced.

[0632] Further, one or both of a conductive film and an insulating film can be commonly used between the transistor Tr1 and the transistor Tr2, so that the number of masks or the number of steps can be reduced.

[0633] ​For example, in the transistor Tr1, the conductive film 320 is used as a gate electrode, the conductive film 312a is used as a source electrode, and the conductive film 312b is used as a drain electrode. Further, in the transistor Tr1, the insulating film 310 is used as a gate insulating film. In the transistor Tr2, the conductive film 312b is used as a first gate electrode, the conductive film 418a is used as a source electrode, the conductive film 418b is used as a drain electrode, and the conductive film 412b is used as a second gate electrode. Further, in the transistor Tr2, the insulating film 318 is used as a first gate insulating film, and the insulating film 410b is used as a second gate insulating film.

[0634] Note that the insulating film 410b is also referred to as a fourth insulating film in this specification and the like.

[0635] The insulating film 336 is provided over the insulating film 416 and the conductive films 418a and 418b. The opening 386 reaching the conductive film 418b is provided in the insulating film 336. Further, the conductive film 338 is provided over the insulating film 336. The conductive film 338 is connected to the conductive film 418a in the opening 386.

[0636] Further, the insulating film 340, the EL layer 342, and the conductive film 344 are provided over the conductive film 338. The light-emitting element 360 is formed of the conductive film 338, the EL layer 342, and the conductive film 344.

[0637] Further, although not illustrated, the transistor Tr1 and the transistor Tr2 illustrated in FIGS. 1A and 1B can have the S-channel structure described in Embodiment 3. FIG. 53B and FIG. 47A The transistor Tr1 and the transistor Tr2 illustrated in FIGS. 1A and 1B can have the S-channel structure described in Embodiment 3.

[0638] The transistor Tr1 and the transistor Tr2 included in the semiconductor device 400 of this embodiment can be combined with the transistor Tr1 and the transistor Tr2 included in the semiconductor device 300 of Embodiment 3.

[0639] As described above, in the semiconductor device of one embodiment of the present application, a plurality of transistors are stacked, whereby the area of the transistors can be reduced. Further, since one or both of an insulating film and a conductive film are commonly used between the plurality of transistors, the number of masks or the number of steps can be reduced.

[0640] <4-2. Constituent elements of semiconductor device>

[0641] Next, the constituent elements of the semiconductor device of this embodiment are described in detail.

[0642] [Conductive film]

[0643] The conductive films 412b, 418a, and 418b can be formed using a material of the conductive films (the conductive film 312a, the conductive film 312b, the conductive film 322a, the conductive film 322b, the conductive film 320, the conductive film 330, the conductive film 338, and the conductive film 344) described in Embodiment Mode 3. In particular, as the conductive film 412b, an oxide conductor (OC) is preferably used because oxygen can be added to the insulating film 410b.

[0644] [Insulating Film]

[0645] The insulating films 414, 416, and 410b can be formed using a material of the insulating films (the insulating film 306, the insulating film 314, the insulating film 316, the insulating film 318, the insulating film 324, the insulating film 326, the insulating film 334, the insulating film 336, and the insulating film 340) described in Embodiment Mode 3.

[0646] Since the insulating film 318 is in contact with the oxide semiconductor film 408, an oxide insulating film is preferably used, and a silicon oxide film or a silicon oxynitride film is particularly preferably used as the insulating film 318. As the insulating film 410b, an oxide insulating film is preferably used. The insulating film 410b preferably has a region in which the oxygen content exceeds the stoichiometric composition (excess-oxygen region). As the insulating film 410b, a silicon oxide film or a silicon oxynitride film is preferably used.

[0647] The insulating film 414 contains one or both of hydrogen and nitrogen. Alternatively, the insulating film 414 contains nitrogen and silicon. The insulating film 414 has a function of blocking oxygen, hydrogen, water, alkali metal, alkaline earth metal, or the like. Since the oxide semiconductor film 408 is in contact with the insulating film 414, one or both of hydrogen and nitrogen in the insulating film 414 enters the oxide semiconductor film 408, whereby the carrier density of the oxide semiconductor film 408 is increased. Thus, a region of the oxide semiconductor film 408 which is in contact with the insulating film 414 is used as a source region or a drain region.

[0648] [Oxide Semiconductor Film]

[0649] The oxide semiconductor film 408 can be formed using a material of the oxide semiconductor films (the oxide semiconductor film 308 and the oxide semiconductor film 328) described in Embodiment Mode 3.

[0650] <4-3. Manufacturing Method of Semiconductor Device>

[0651] Next, a manufacturing method of the semiconductor device 400 of one embodiment of the present application will be described with reference to FIG. 48A and FIG. 49A and FIG. 50A

[0652] Further, FIG. 51A , FIG. 52A , FIG. 53A ​, FIG. 47B , FIG. 48B , FIG. 49B and FIG. 50B are cross-sectional views illustrating a method for manufacturing the semiconductor device 400. FIG. 51B , FIG. 52B , FIG. 53B , FIG. 36A , FIG. 36B to FIG. 38A , FIG. 38B and FIG. 47A are cross-sectional views illustrating a method for manufacturing the semiconductor device 400.

[0653] As a method for manufacturing the transistor Tr1, the method described in Embodiment 3 can be used. Thus, as a method for forming the insulating film 306, the oxide semiconductor film 308, the insulating film 310, the conductive film 320, the insulating film 314, the insulating film 316, the conductive film 312a, the conductive film 312b, and the insulating film 318 over the substrate 302, the method described in Embodiment 3 and FIG. 47B and FIG. 48A and FIG. 48B .

[0654] Then, the insulating film 318 is formed over the insulating film 316 and the conductive films 312a and 312b. The insulating film 318 can be formed by the method described in Embodiment 3.

[0655] Next, the oxide semiconductor film 408 is formed over the insulating film 318 (see FIG. 49A and FIG. 49B ).

[0656] In this embodiment, the oxide semiconductor film is formed by a sputtering method using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic percentage ratio]). The substrate temperature at the time of formation of the oxide semiconductor film is 170 °C. As a deposition gas at the time of formation of the oxide semiconductor film, an oxygen gas with a flow rate of 60 seem and an argon gas with a flow rate of 140 seem are used. Then, the oxide semiconductor film is processed into a desired shape, whereby the island-shaped oxide semiconductor film 408 is formed. Note that a wet etching apparatus is used at the time of formation of the oxide semiconductor film.

[0657] Next, a stacked film including an insulating film and a conductive film is formed over the insulating film 318 and the oxide semiconductor film 408. Then, the stacked film is processed into a desired shape, whereby the island-shaped insulating film 410b and the island-shaped conductive film 412b are formed (see FIG. 49A and FIG. 49B ).

[0658] Next, an insulating film 414 and an insulating film 416 are formed over the insulating film 318, the oxide semiconductor film 408, and the conductive film 412b. By forming the insulating film 414, the oxide semiconductor film 408 is in contact with the insulating film 414 and is used as a source region 408s and a drain region 408d. The oxide semiconductor film 408 which is not in contact with the insulating film 414, that is, the oxide semiconductor film 408 which is in contact with the insulating film 410b is used as a channel region 408i. Thus, the oxide semiconductor film 408 including the channel region 408i, the source region 408s, and the drain region 408d is formed (see FIG. 49A and FIG. 49B ).

[0659] In this embodiment, as the insulating film 410b, a silicon oxynitride film with a thickness of 50 nm is formed using a PECVD apparatus. As the conductive film 412b, an oxide semiconductor film with a thickness of 200 nm is formed using a sputtering apparatus. Further, the oxide semiconductor film has the same composition as the oxide semiconductor film 408. As the insulating film 414, a silicon nitride film with a thickness of 100 nm is formed by a PECVD apparatus. As the insulating film 416, a silicon oxynitride film with a thickness of 200 nm is formed using a PECVD apparatus.

[0660] By using the silicon nitride film as the insulating film 414, one or both of hydrogen and nitrogen in the silicon nitride film enter the conductive film 412b, the source region 408s, and the drain region 408d which are in contact with the insulating film 414, and thus the carrier density of the conductive film 412b, the source region 408s, and the drain region 408d can be increased. As a result, the region of part of the oxide semiconductor film 408 and the conductive film 412b become an oxide conductor (OC).

[0661] Further, the insulating film 410b is formed self-aligned using the conductive film 412b as a mask.

[0662] Next, openings 482a and 482b reaching the oxide semiconductor film 408 are formed in desired regions of the insulating films 414 and 416 (see FIG. 50A and FIG. 50B ).

[0663] The openings 482a and 482b are formed using a dry etching apparatus or a wet etching apparatus.

[0664] Next, a conductive film is formed over the insulating film 416 and the oxide semiconductor film 408 so as to fill the openings 482a and 482b, and is processed into an island shape, whereby conductive films 418a and 418b are formed (see FIG. 51A and FIG. 51B ).

[0665] As the conductive films 418a and 418b, a tungsten film having a thickness of 100 nm and a copper film having a thickness of 200 nm are formed by a sputtering method.

[0666] Through the above process, the transistor Tr2 can be manufactured.

[0667] Next, the insulating film 336 is formed over the insulating film 416 and the conductive films 418a and 418b. Then, a desired region of the insulating film 336 is processed, and the opening 386 reaching the conductive film 418a is formed (see FIG. 52A and FIG. 52B ).

[0668] In this embodiment, as the insulating film 336, a photosensitive acrylic resin film having a thickness of 1.5 μm is formed.

[0669] Next, a conductive film is formed over the insulating film 336 and the conductive film 418a, and is processed into an island shape, whereby the conductive film 338 is formed (see FIG. 53A and FIG. 53B ).

[0670] As the conductive film 338 in this embodiment, a laminated film of an ITO film having a thickness of 10 nm, a reflective metal film (here, a metal film containing silver, palladium, and copper) having a thickness of 200 nm, and an ITO film having a thickness of 10 nm is used. This laminated film is processed into the conductive film 338 using a wet etching apparatus.

[0671] Next, the island-shaped insulating film 340 is formed over the insulating film 336 and the conductive film 338 (see FIG. 46A and FIG. 46B ).

[0672] As the insulating film 340, a photosensitive polyimide resin film having a thickness of 1.5 μm is used.

[0673] Next, the EL layer 342 is formed over the conductive film 338, and then the conductive film 344 is formed over the insulating film 340 and the EL layer 342, whereby the light-emitting element 360 is obtained (see FIG. 54 and ​ ).

[0674] Note that the method for manufacturing the light-emitting element 360 will be described in detail in Embodiment 5.

[0675] Through the above manufacturing process, the semiconductor device 400 illustrated in ​ and ​ can be manufactured.

[0676] The structure and the method described in this embodiment can be combined with the structures and the methods described in other embodiments as appropriate.

[0677] Embodiment 5

[0678] In this embodiment, a light-emitting element which can be used for a semiconductor device of one embodiment of the present application will be described with reference to ​ , Figures 55A-55D and Figure 56

[0679] <51. Structure Example of Light-Emitting Element>

[0680] First, a structure of a light-emitting element which can be used for a semiconductor device of one embodiment of the present application will be described with reference to Figure 54 Figure 54 is a cross-sectional view of the light-emitting element 160.

[0681] Note that as the light-emitting element 160, one or both of an inorganic compound and an organic compound can be used. As the organic compound used for the light-emitting element 160, a low molecular compound or a high molecular compound can be used. The high molecular compound has heat resistance and can easily form a thin film with high uniformity by a coating method or the like, and is thus preferable.

[0682] Figure 54 The light-emitting element 160 illustrated in FIG. 1 includes a pair of electrodes (the conductive film 138 and the conductive film 144) and an EL layer 142 between the pair of electrodes. The EL layer 142 includes at least a light-emitting layer 150.

[0683] Figure 54 The EL layer 142 illustrated in FIG. 1 includes the light-emitting layer 150 and functional layers such as a hole-injection layer 151, a hole-transport layer 152, an electron-transport layer 153, and an electron-injection layer 154.

[0684] In this embodiment, the conductive film 138 and the conductive film 144 in the pair of electrodes are described to be used as an anode and a cathode, respectively, but the structure of the light-emitting element 160 is not limited thereto. For example, a structure in which the conductive film 138 and the conductive film 144 are used as a cathode and an anode, respectively, and layers between the electrodes are stacked in reverse order can be used. In other words, the hole-injection layer 151, the hole-transport layer 152, the light-emitting layer 150, the electron-transport layer 153, and the electron-injection layer 154 can be stacked in this order from the anode side.

[0685] The structure of the EL layer 142 is not limited to Figure 54 ​​The structure shown can be used as long as it is a structure including the light-emitting layer 150, and at least one of the hole-injection layer 151, the hole-transport layer 152, the electron-transport layer 153, and the electron-injection layer 154. The EL layer 142 can also include a functional layer that is, for example, capable of reducing an injection barrier of holes or electrons; capable of increasing the transportability of holes or electrons; capable of impeding the transportability of holes or electrons; or capable of suppressing a quenching phenomenon caused by an electrode, and the like. Furthermore, the functional layer can be a single layer or a stacked layer.

[0686] A low molecular compound or a high molecular compound can be used for the light-emitting layer 150.

[0687] In this specification and the like, a high molecular compound refers to a compound having a molecular weight distribution and an average molecular weight of 1 x 10 3 to 1 x 10 8 A low molecular compound refers to a compound having no molecular weight distribution and an average molecular weight of 1 x 10 4 to 1 x 10

[0688] A high molecular compound refers to a compound in which one or more constitutional units are polymerized. In other words, the constitutional unit refers to a unit of which at least one is included in the high molecular compound.

[0689] A high molecular compound can also refer to a block polymer, a random copolymer, an alternating copolymer, or a graft copolymer, and the like.

[0690] In the case where an end group of a high molecular compound has a polymerization active group, the light-emitting properties and the luminance lifetime of the light-emitting element can possibly be reduced. Therefore, the end group of the high molecular compound is preferably a stable end group. As the stable end group, a group that forms a covalent bond with the main chain is preferable. A group that is bonded to an aryl group or a heterocyclic group through a carbon-carbon bond is particularly preferable.

[0691] In the case where a low molecular compound is used for the light-emitting layer 150, a light-emitting low molecular compound is preferably contained as a guest material in addition to the low molecular compound used as a host material. In the light-emitting layer 150, the weight ratio of the host material is greater than that of the guest material, and the guest material is dispersed in the host material.

[0692] As the guest material, a light-emitting organic compound can be used. As the light-emitting organic compound, a substance that is capable of emitting fluorescence (hereinafter, also referred to as a fluorescent compound) or a substance that is capable of emitting phosphorescence (hereinafter, also referred to as a phosphorescent compound) can be used.

[0693] In the light-emitting element 160 of one embodiment of the present application, current flows by application of voltage to a pair of electrodes (the conductive film 138 and the conductive film 144) between which an EL layer 142 is interposed, whereby electrons and holes are injected from the cathode and the anode into the EL layer 142. The injected electrons and holes recombine to form excitons. The statistical probability of the ratio of singlet excitons to triplet excitons (hereinafter referred to as the exciton generation probability) is approximately 1:3. Thus, in a light-emitting element including a fluorescent compound, the generation ratio of singlet excitons which contribute to light emission is 25 % and the generation ratio of triplet excitons which do not contribute to light emission is 75 %. In a light-emitting element including a phosphorescent compound, both singlet excitons and triplet excitons can contribute to light emission. Thus, the light-emitting element including a phosphorescent compound is more preferable than the light-emitting element including a fluorescent compound in terms of the emission efficiency, and is thus preferred.

[0694] Note that an "exciton" refers to a pair of carriers (an electron and a hole). Since an exciton has energy, a material from which an exciton is generated is in an excited state.

[0695] In the case where a high molecular compound is used for the light-emitting layer 150, the high molecular compound preferably includes a skeleton having a function of transporting holes (hole-transport property) and a skeleton having a function of transporting electrons (electron-transport property) as a constituent unit. Alternatively, the high molecular compound preferably has at least one of a π-electron rich heteroaromatic skeleton and an aromatic amine skeleton and a π-electron deficient heteroaromatic skeleton. The above-described skeletons are bonded to each other directly or through other skeletons.

[0696] In the case where the high molecular compound includes a skeleton having a hole-transport property and a skeleton having an electron-transport property, the balance of carriers can be easily controlled. Thus, the region where carriers recombine can be easily controlled. For this reason, the proportion of the skeleton having a hole-transport property to the skeleton having an electron-transport property is preferably in the range of 1:9 to 9:1 (molar ratio). It is more preferable that the proportion of the skeleton having an electron-transport property be higher than that of the skeleton having a hole-transport property.

[0697] The high molecular compound can include a skeleton having a light-emitting property as a constituent unit in addition to the skeleton having a hole-transport property and the skeleton having an electron-transport property. In the case where the high molecular compound has a skeleton having a light-emitting property, the proportion of the skeleton having a light-emitting property to the entire constituent units of the high molecular compound is preferably low, and specifically, is preferably greater than or equal to 0.1 mol % and less than or equal to 10 mol %, more preferably greater than or equal to 0.1 mol % and less than or equal to 5 mol %.

[0698] Furthermore, the bonding direction, the bond angle, the bond length, or the like of each constituent unit of the high molecular compound used for the light-emitting element 160 are sometimes different. Furthermore, each constituent unit can have a different substituent and can have a different skeleton between the constituent units. Furthermore, the polymerization method of each constituent unit can be different.

[0699] The light-emitting layer 150 can contain a light-emitting low molecular compound as a guest material in addition to the high molecular compound used as a host material. At this time, the light-emitting low molecular compound is dispersed as a guest material in the high molecular compound used as a host material, and the weight ratio of the high molecular compound is at least greater than that of the light-emitting low molecular compound. The weight ratio of the light-emitting low molecular compound to the high molecular compound is preferably greater than or equal to 0.1 wt% and less than or equal to 10 wt%, more preferably greater than or equal to 0.1 wt% and less than or equal to 5 wt%.

[0700] Next, the components of the light-emitting element of one embodiment of the present application will be described in detail.

[0701] [Light-emitting layer]

[0702] Next, a material that can be used for the light-emitting layer 150 will be described.

[0703] Although there is no particular limitation on the high molecular compound that can be used for the light-emitting layer 150, the high molecular compound preferably contains at least one of a heteroaromatic skeleton and an arene skeleton. The skeletons are preferably bonded directly to each other or through an arylene group or an alkylene group. Note that the skeletons can be bonded through a group other than an arylene group and an alkylene group.

[0704] The high molecular compound preferably has one or more selected from a furan skeleton, a thiophene skeleton, and a pyrrole skeleton, because these skeletons have high stability and reliability. A pyridine skeleton, a diazine skeleton (a pyrazine skeleton, a pyrimidine skeleton, and a pyridazine skeleton), and a triazine skeleton, and in particular, a diazine skeleton and a triazine skeleton are preferable because they are stable and have high reliability. For example, a furan skeleton, a benzofuran skeleton, a dibenzofuran skeleton, a benzodifuran skeleton, a thiophene skeleton, a benzothiophene skeleton, a dibenzothiophene skeleton, a benzodithiophene skeleton, a thienothiophene skeleton, a dithienothiophene skeleton, a dithienofuran skeleton, a dithienoselenophene skeleton, a cyclopentadithiophene skeleton, a dithienosilole skeleton, a thienopyrrole skeleton, a dithienopyrrole skeleton, a thienoindole skeleton, a thienopyridine skeleton, a thienopyrazine skeleton, a thiazole skeleton, a thiadiazole skeleton, a benzothiazole skeleton, a benzodithiazole skeleton, an oxazole skeleton, an oxadiazole skeleton, a benzoxazole skeleton, a benzoxadiazole skeleton, a selenophene skeleton, a benzoselenophene skeleton, a dibenzoselenophene skeleton, a benzoselenadiazole skeleton, a selenoloselenophene skeleton, an indacenothiophene skeleton, an indacenodithiophene skeleton, an indacenoselenophene skeleton, an indacenoselenadiazole skeleton, a pyrrole skeleton, an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bis-carbazole skeleton, a pyrrolopyrrole skeleton, a 9,10-dihydroacridan skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a phenoxazine skeleton, a phenazasiline skeleton, an azepine skeleton, a gronolithine skeleton, and the like can be used. For example, a quinoline skeleton, a naphthylidine skeleton, a quinoxaline skeleton, a quinazoline skeleton, a phthalazine skeleton, a cinnoline skeleton, a pteridine skeleton, an acridine skeleton, a phenanthridine skeleton, a phenanthroline skeleton, a benzoquinoline skeleton, a benzoquinoxaline skeleton, a benzoquinazoline skeleton, a dibenzoquinoline skeleton, a dibenzoquinoxaline skeleton, a dibenzoquinazoline skeleton, an imidazole skeleton, a pyrazole skeleton, a triazole skeleton, a benzimidazole skeleton, an imidazopyridine skeleton, a purine skeleton, a triazolopyrimidine skeleton, a triazolopyridine skeleton, an indazole skeleton, and the like can be used.

[0705] In addition, an aromatic hydrocarbon skeleton can also be used instead of the above-described heteroaromatic skeleton. As examples of the aromatic hydrocarbon skeleton, there are a biphenyl skeleton, a naphthalene skeleton, an anthracene skeleton, a chrysene skeleton, a phenanthrene skeleton, a triphenylene skeleton, a fluorene skeleton, a spirofluorene skeleton, an indacene skeleton, a dibenzosilole skeleton.

[0706] The aromatic amine skeleton can be included in the high molecular compound, and a secondary amine skeleton or a tertiary amine skeleton is preferable. A triarylamine skeleton is particularly preferable. As the aryl group of the triarylamine skeleton, a substituted or unsubstituted aryl group having 6 to 13 carbon atoms forming a ring is preferably used, and as examples thereof, there are phenyl, naphthyl, fluorenyl. For example, a triphenylamine skeleton, a phenylenediamine skeleton, a naphthylenediamine skeleton, a benzidine skeleton, and the like can be given.

[0707] A ketone skeleton, an alkoxy skeleton, and the like can be included in the high molecular compound.

[0708] In the case where the above-described aromatic amine skeleton, heteroaromatic skeleton, and arene skeleton are bonded via an arylene group or an alkylene group, as examples of the arylene group and the alkylene group, there are phenylene, biphenyldiyl, terphenyldiyl, naphthalenediyl, fluorenediyl, anthracenediyl, 9,10-dihydroanthracenediyl, phenanthrenediyl, pyrenediyl, perylenediyl, chrysenediyl, alkoxyphenylene, arylenevinylene (phenylenevinylene and the like), and vinylene. In addition, an ether bond, a thioether bond, an ester bond, and the like can also be used.

[0709] ​The above aromatic amine skeleton, heteroaromatic skeleton, arene skeleton, above arylene group, and alkylene group can have a substituent. As the substituent, an alkyl group having 1 to 20 carbon atoms, an alkoxy group or an alkylthio group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted aryl group or aryloxy group having 6 to 18 carbon atoms, or a heterocyclic compound group having 4 to 14 carbon atoms can be selected. As specific examples of the alkyl group having 1 to 20 carbon atoms, there are a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group, a dodecyl group, a 2-ethylhexyl group, a 3-methylbutyl group, and the like. Further, as specific examples of the alkoxy group having 1 to 20 carbon atoms, there are a methoxy group, an ethoxy group, a butoxy group, a pentoxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a decyloxy group, a dodecyloxy group, a 2-ethylhexyloxy group, a 3-methylbutoxy group, an isopropoxy group, and the like. Further, as specific examples of the alkylthio group having 1 to 20 carbon atoms, there are a methylthio group, an ethylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, an octylthio group, a decylthio group, a dodecylthio group, a 2-ethylhexylthio group, a 3-methylbutylthio group, an isopropylthio group, and the like. As specific examples of the cycloalkyl group having 3 to 20 carbon atoms, there are a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, a noradamantyl group, an adamantyl group, a homoadamantyl group, a tricyclodecyl group, and the like. As specific examples of the aryl group having 6 to 18 carbon atoms, there are a substituted or unsubstituted phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, an anthryl group, a pyrenyl group, and the like. As specific examples of the aryloxy group having 6 to 18 carbon atoms, there are a substituted or unsubstituted alkyloxyphenyl group, an alkylphenoxy group, a naphthyloxy group, an anthryloxy group, a pyrenyloxy group, and the like. As specific examples of the heterocyclic compound group having 4 to 14 carbon atoms, there are a substituted or unsubstituted thienyl group, a pyrrolyl group, a furanyl group, a pyridyl group, and the like. The above substituents can be bonded to each other to form a ring. For example, when the carbon at the 9-position of the fluorene skeleton has two phenyl groups as substituents, the phenyl groups are bonded to each other to form a spiro fluorene skeleton. In addition, the unsubstituted group is advantageous in terms of easiness of synthesis and price of raw material.

[0710] As examples of the above-mentioned high molecular compound, there are: polyphenylenevinylene (PPV) derivatives such as poly[2-methoxy-5-(2-ethylhexyloxy)-l,4- phenylenevinylene] (abbreviation: MEH-PPV), poly(2,5-dioctyl-l,4-phenylenevinylene), and the like; polyfluorene derivatives such as poly(9,9-di-n-octylfluorene-2,7-diyl) (abbreviation: PF8), poly[(9,9-di-n-octylfluorene-2,7-diyl)-alt-(benzo[2,l,3]thiadiazole-4,8-diyl)] (abbreviation: F8BT), poly[(9,9-di-n-octylfluorene-2,7-diyl)-alt-(2,2'-bithiophene-5,5'-diyl)] (abbreviation: F8T2), poly[(9,9-dioctyl-2,7-divinylenefluorenylene)-alt-(9,10-anthracene)], poly[(9,9-dihexyl-2,7-fluorene-diyl)-alt-(2,5-dimethyl-l,4-phenylene)], and the like; polyalkylthiophene (PAT) derivatives such as poly(3-hexylthiophene-2,5-diyl) (abbreviation: P3HT), and the like, polyphenyl derivatives, and the like. The above-mentioned high molecular compound, poly(9-vinylcarbazole) (abbreviation: PVK), poly(2-vinylnaphthalene), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (abbreviation: PTAA), and the like high molecular compound can also be doped with a light-emitting low molecular compound, and used for the light-emitting layer.

[0711] There is no particular limitation on the fluorescent compound that can be used for the light-emitting layer 150, but anthracene derivatives, tetracene derivatives, (chrysene) derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, phenothiazine derivatives, and the like are preferable. For example, substituted or unsubstituted materials of the materials shown below can be used. As the substituents, the above-mentioned substituents can be used. The substituents are preferably aliphatic hydrocarbon groups, more preferably alkyl groups, and further preferably branched alkyl groups.

[0712] As examples of the material, there are: 5,6-bis[4(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-bis(4-tert-butylphenyl)pyrene-1,6-diamine (abbreviation: 1,6tBu-FLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-diphenyl-3,8-dicyclohexylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N"-(2-tert-butylanthracen-9,10-diylbis-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N",N",N",N"'-octaphenyl-2,3- dihydro-1J,1J-dibenzo[g,p] (chrysene)-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1 '-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1 '-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1 '-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), coumarin 6, coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenylbenzo[2,1,2]thiophorin (abbreviation: TBRb), Nile red, 5,12-bis(1,1 '-biphenyl-4-yl)-6,11-diphenylbenzo[2,1,2]thiophorin (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4- ylidene)malonitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1 H,5H- benzo[ij]quinolizol-9-yl)ethenyl]-4H-pyran-4-ylidene}malonitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)benzo[2,1,3]thiophorin-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1 H,5H- benzo[ij]quinolizol-9-yl)ethenyl]-4H-pyran-4-ylidene}malonitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1 H,5H-benzo[ij]quinolizol-9-yl)ethenyl]-4H-pyran-4-ylidene}malonitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)malonitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1 H,5H-5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]pentalene,

[0713] Although there is no particular limitation on the light-emitting skeleton that can be used for the high molecular compound, it is preferable to use a structure in which one or two hydrogens are removed from the aromatic heterocycle of the skeleton of anthracene, naphthacene, (chrysene), phenanthrene, pyrene, perylene, stilbene, acridone, coumarin, phenoxazine, phenothiazine, or the like. As the substituent, the above substituents can be used. In addition, an aliphatic hydrocarbon group, preferably an alkyl group, more preferably a branched alkyl group, can be introduced as the substituent.

[0714] As the phosphorescent compound, an iridium, rhodium, platinum, or metal complex organic metal complex, or a metal complex can be used, of which an organic iridium complex, such as an iridium ortho metal complex, is preferable. As the ortho metalated ligand, a 4H-triazole ligand, a 1H-triazole ligand, an imidazole ligand, a pyridine ligand, a pyrimidine ligand, a pyrazine ligand, or an isoquinoline ligand, or the like can be given. As the metal complex, a platinum complex having a porphyrin ligand, or the like can be given. For example, the following substituted or unsubstituted materials can be used. As the substituent, the above substituents can be used.

[0715] As examples of the substance having a light emission peak in the wavelength range of blue or green, there are: tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-l,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: Ir(mpptz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-l,2,4-triazole)iridium(III) (abbreviation: Ir(Mptz)3), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-l,2,4-triazole]iridium(III) (abbreviation: Ir(iPrptz-3b)3), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-l,2,4-triazole]iridium(III) (abbreviation: Ir(iPr5btz)3), and the like having a 4H-triazole skeleton; tris[3-methyl-l-(2-methylphenyl)-5-phenyl-lH-l,2,4-triazole]iridium(III) (abbreviation: Ir(Mptzl-mp)3), tris(l-methyl-5-phenyl-3-propyl-lH-l,2,4-triazole)iridium(III) (abbreviation: Ir(Prptzl-Me)3), and the like having a lH-triazole skeleton; fac-tris[l-(2,6-diisopropylphenyl)-2-phenyl-lH-imidazole]iridium(III) (abbreviation: Ir(iPrpmi)3), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[l,2-f]phenanthridinato]iridium(III) (abbreviation: Ir(dmpimpt-Me)3), and the like having an imidazole skeleton; and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetra(l-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) picolinate (abbreviation: Ir(CF3ppy)2(pic)), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) acetylacetonate (abbreviation: FIr(acac)), and the like having a phenylpyridine derivative having an electron-withdrawing group as a ligand. Among the above metal complexes, the organic metal iridium complex having a 4H-triazole skeleton has high reliability and high emission efficiency, and thus is particularly preferable.

[0716] As examples of substances having a light emission peak in the green or yellow wavelength range, there are: tris(4-methyl-6-phenylpyrimidine)iridium(III) (abbreviation: Ir(mppm)3), tris(4-tert-butyl-6-phenylpyrimidine)iridium(III) (abbreviation: Ir(tBuppm)3), (acetylacetonato)bis(6-methyl-4-phenylpyrimidine)iridium(III) (abbreviation: Ir(mppm)2(acac)), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidine)iridium(III) (abbreviation: Ir(tBuppm)2(acac)), (acetylacetonato)bis[4-(2-norbomyl)-6-phenylpyrimidine]iridium(III) (abbreviation: Ir(nbppm)2(acac)), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidine]iridium(III) (abbreviation: Ir(mpmppm)2(acac)), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: Ir(dmppm-dmp)2(acac)), (acetylacetonato)bis(4,6-diphenylpyrimidine)iridium(III) (abbreviation: Ir(dppm)2(acac)), and the like organic metal iridium complexes having a pyrimidine skeleton; (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazine)iridium(III) (abbreviation: Ir(mppr-Me)2(acac)), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazine)iridium(III) (abbreviation: Ir(mppr-iPr)2(acac)), and the like organic metal iridium complexes having a pyrazine skeleton; tris(2-phenylpyridine-N,C 2’ )iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenylpyridine-N,C 2’ )iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(acac)), bis(benzo[h]quinoline)iridium(III) acetylacetonate (abbreviation: Ir(bzq)2(acac)), tris(benzo[h]quinoline)iridium(III) (abbreviation: Ir(bzq)3), tris(2-phenylquinoline-N,C 2′ )iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinoline-N,C 2’ )iridium(III) acetylacetonate (abbreviation: Ir(pq)2(acac)), and the like organic metal iridium complexes having a pyridine skeleton; bis(2,4-diphenyl-1,3-oxazole-N,C 2’ )iridium(III) acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl)phenyl]pyridine-N,C 2’iridium(III) acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazole-N,C 2’ )iridium(III) acetylacetonate (abbreviation: Ir(bt)2(acac)), and the like; and a rare earth metal complex such as tris(acetylacetonato) (monophenanthroline) terbium(III) (abbreviation: Tb(acac)3(Phen)). Among the above metal complexes, an organic metal iridium complex having a pyrimidine skeleton is particularly preferable because of its excellent reliability and luminous efficiency.

[0717] As examples of substances having a luminescence peak in the wavelength range of yellow or red, there are an organic metal iridium complex having a pyrimidine skeleton such as (diisobutyromethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinato](dineopentylmethanato)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-bis(naphthalen-1-yl)pyrimidinato](dineopentylmethanato)iridium(III) (abbreviation: Ir(d1npm)2(dpm)), and the like; an organic metal iridium complex having a pyrazine skeleton such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: Ir(tppr)2(acac)), bis(2,3,5-triphenylpyrazinato)(dineopentylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalino]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), and the like; an organic metal iridium complex having a pyridine skeleton such as tris(1-phenylisoquinoline-N,C 2’ )iridium(III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinoline-N,C 2’ )iridium(III) acetylacetonate (abbreviation: Ir(piq)2(acac)), and the like; a platinum complex such as 2,3,7,8,12,13,17,18-octylethyl-21H,23H-porphine platinum(II) (abbreviation: PtOEP); and a rare earth metal complex such as tris(1,3-diphenyl-1,3-propanedionato) (monophenanthroline) europium(III) (abbreviation: Eu(DBM)3(Phen)), tris[1-(2-thienoyl)-3,3,3-trifluoropropanedionato] (monophenanthroline) europium(III) (abbreviation: Eu(TTA)3(Phen)), and the like. Among the above metal complexes, an organic metal iridium complex having a pyrimidine skeleton is particularly preferable because of its excellent reliability and luminous efficiency. In addition, an organic metal iridium complex having a pyrazine skeleton can provide red luminescence with good color rendering.

[0718] The phosphorescent compound can be a high molecular compound, for example, preferably a high molecular compound containing an iridium-based, rhodium-based, or platinum-based organometallic complex or a metal complex as a constituent unit. That is, a structure in which one or two hydrogens are removed from an iridium-based, rhodium-based, or platinum-based organometallic complex or a metal complex, and the like is preferably used as a constituent unit.

[0719] As the organic compound contained in the light-emitting layer 150, any material can be used as long as it is a substance capable of converting a triplet excitation energy into light emission. As the substance capable of converting a triplet excitation energy into light emission, in addition to a phosphorescent compound, a thermally activated delayed fluorescence (TADF) substance can be given. Thus, the portion described as "phosphorescent compound" can be referred to as "thermally activated delayed fluorescence substance". Note that the thermally activated delayed fluorescence substance is a substance in which the difference between the triplet excitation energy level and the singlet excitation energy level is small and which has a function of converting energy from a triplet excitation state to a singlet excitation state by reverse intersystem crossing. Thus, the TADF substance can up-convert a triplet excitation state to a singlet excitation state using a small amount of thermal energy (i.e., reverse intersystem crossing) and can efficiently emit light (fluorescence) from a singlet excitation state. The condition in which TADF can be efficiently obtained is as follows: the energy difference between the triplet excitation energy level and the singlet excitation energy level is preferably greater than 0 eV and is 0.2 eV or less, more preferably greater than 0 eV and is 0.1 eV or less.

[0720] As the TADF substance which is a thermally activated delayed fluorescence substance, for example, the following substances can be used.

[0721] First, fullerene or a derivative thereof, a pyrylium derivative such as aurophorin, eosin, and the like can be given. As other examples, a metal-containing porphyrin containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), or the like can be given. As examples of the metal-containing porphyrin, protoporphyrin-tin fluoride complex (abbreviation: SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF2(Meso IX)), hematoxylin-tin fluoride complex (abbreviation: SnF2(Hemato IX)), copro porphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviation: SnF2(OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF2(Etio I)), octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2OEP) can be given.

[0722] As the thermally activated delayed fluorescence substance composed of one material, a heterocyclic compound having a π-electron rich heteroaromatic ring and a π-electon deficient heteroaromatic ring can also be used. Specifically, 2-(diphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenoxazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridin)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine 9,9'anthracene]10'one (abbreviation: ACRSA) can be used. This heterocyclic compound has a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, and thus has high electron-transport property and hole-transport property, and is preferable. In addition, a substance in which a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring are directly bonded is particularly preferable because the donor property of the π-electron rich heteroaromatic ring and the acceptor property of the π-electron deficient heteroaromatic ring are both strong, and the difference between the singlet excitation energy level and the triplet excitation energy level is small.

[0723] As the material exhibiting thermally activated delayed fluorescence, a combination of two materials forming an exciplex can also be used. As the combination of two materials, a combination of the above-described material having a hole-transport property and a material having an electron-transport property is preferable. Specifically, a zinc or aluminum complex, an oxadiazole derivative, a triazole derivative, a benzimidazole derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a dibenzothiophene derivative, a dibenzofuran derivative, a pyrimidine derivative, a triazine derivative, a pyridine derivative, a bipyridine derivative, a phenanthroline derivative, or the like can be used. As other examples, there are aromatic amine and carbazole derivatives.

[0724] In the light-emitting layer 150, other substances can be contained in addition to the compound used as the host material and the compound used as the light-emitting guest material. For example, a substituted or unsubstituted material of a hole-transport material and an electron-transport material described below can be used. In addition, as the substituent, the above-described substituent can be used.

[0725] As the hole-transport material, a material having higher hole-transport property than electron-transport property can be used, and a material having a hole-transport property of 1 x 10 -6cm 2 A material having a hole mobility of 10"Vs or more. Specifically, an aromatic amine, a carbazole derivative, an arene, a stilbene derivative, or the like can be used. In addition, the above hole-transporting material can also be a high molecular compound. In addition, a high molecular compound containing a hole-transporting skeleton, a π-electron rich heteroaromatic skeleton, an aromatic amine skeleton, which are contained in the above high molecular compound, can also be used.

[0726] Examples of a material having a high hole-transporting property are aromatic amine compounds such as N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(l,l'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), and the like.

[0727] Specific examples of a carbazole derivative are 3-[N-(4-diphenylaminophenyl)-N- phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4- diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(l-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(l-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), and the like.

[0728] Other examples of a carbazole derivative are 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tri[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, and the like.

[0729] Examples of the aromatic hydrocarbon are 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(l-naphthyl)anthracene, 9,10-bis(3,5- diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4- phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-l-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9,10-bis[2-(l-naphthyl)phenyl]anthracene, 9,10-bis[2-(l- naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(l-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthracene, 10,10'-diphenyl-9,9'-bianthracene, 10,10'-bis(2-phenylphenyl)-9,9'-bianthracene, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthracene, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, and the like. Other examples are pentacene, coronene, and the like. More preferably, an aromatic hydrocarbon having a hole mobility of 1 x 10 - 6 cm 2 a hole mobility of 1 x 10

[0730] The aromatic hydrocarbon can also have a vinyl skeleton. As the aromatic hydrocarbon having a vinyl skeleton, 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA), and the like can be given.

[0731] Other examples are poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'- phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), poly[N,N'-bis(4- butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD), and the like high molecular compounds.

[0732] Examples of materials having a high hole-transport property are 4,4'-bis[N-(l-naphthyl)-N- phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'- diphenyl-[l,r-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4"-tris(carbazol-9-yl) triphenylamine (abbreviation: TCTA), 4,4',4"-tris[N-(l-naphthyl)-N-phenylamino]triphenylamine (abbreviation: l'-TNATA), 4,4',4"-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4"-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-bifluorene-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(l-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(l-naphthyl)-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCAlBP), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-l,3-diamine (abbreviation: PCA2B), N,N',N"-triphenyl-N,N',N"-tris(9-phenylcarbazol-3-yl)benzene-l,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(l,l'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'- bifluorene-2-amine (abbreviation: PCBASF), 2-[N-(9-phenylcarbazol-3-yl)-N- phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-bis[N-(4- diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylamine (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), and the like. Other examples are 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,6-di(9H-carbazol-9-yl)-9-phenyl-9H-carbazole (abbreviation: PhCzGI), 2,8-di(9H-carbazol-9-yl)-dibenzothiophene (abbreviation: Cz2DBT), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4',4''-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tris(dibenzothiophene-4-yl)-benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II), and the like. The substances described here are mainly substances having a hole mobility of 1 x 10 -6 cm 2 Vs or higher. Note that a substance other than the above substances can be used as long as the substance is a substance whose hole-transport property is higher than its electron-transport property.

[0733] As the electron-transporting material, a material having higher electron-transporting property than hole-transporting property can be used, and preferably a material having an electron mobility of 1 x 10 -6 cm 2 or more is used. As the material that easily receives an electron (material having electron-transporting property), a π-electron deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. As specific examples of the metal complex, there are metal complexes including quinoline ligand, benzoquinoline ligand, oxazole ligand, and thiazole ligand. In addition, oxadiazole derivative, triazole derivative, phenanthroline derivative, pyridine derivative, bipyridine derivative, pyrimidine derivative, and the like can be given. In addition, the electron-transporting material can also be a high molecular compound. Furthermore, a high molecular compound having an electron-transporting skeleton or a π-electron deficient heteroaromatic skeleton included in the above high molecular compound can also be used.

[0734] As examples thereof, there are metal complexes having a quinoline or a benzoquinoline skeleton such as tris(8-hydroxyquinoline)aluminum (III) (abbreviation: Alq), tris(4-methyl-8- hydroxyquinoline)aluminum (III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinoline)beryllium (II) (abbreviation: BeBq2), bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum (III) (abbreviation: BAlq), bis(8-hydroxyquinoline)zinc (II) (abbreviation: Znq), and the like. In addition, metal complexes having oxazole or thiazole ligands such as bis[2-(2-benzoxazolyl)phenol]zinc (II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenol]zinc (II) (abbreviation: ZnBTZ), and the like can be used. In addition to such metal complexes, heterocyclic compounds such as 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-o...

Claims

1. A semiconductor device comprising a pixel, the pixel comprising: First transistor; Second transistor; Capacitor; as well as Light-emitting elements The first transistor includes: First gate electrode; The first oxide semiconductor film on the first gate electrode; and The second gate electrode, the first source electrode, and the first drain electrode are on the first oxide semiconductor film. The second transistor includes: One of the first source electrode and the first drain electrode, which serves as the third gate electrode; The second oxide semiconductor film on the third gate electrode; and The fourth gate electrode, the second source electrode, and the second drain electrode are located on the second oxide semiconductor film. One of the first source electrode and the first drain electrode is electrically connected to the first electrode of the capacitor. The first gate electrode is electrically connected to the second gate electrode. Furthermore, the first oxide semiconductor film and the second oxide semiconductor film at least partially overlap each other.

2. A semiconductor device comprising a pixel, the pixel comprising: First transistor; Second transistor; Capacitor; as well as Light-emitting elements The first transistor includes: First gate electrode; The first oxide semiconductor film on the first gate electrode; and The second gate electrode, the first source electrode, and the first drain electrode are on the first oxide semiconductor film. The second transistor includes: One of the first source electrode and the first drain electrode, which serves as the third gate electrode; The second oxide semiconductor film on the third gate electrode; and The fourth gate electrode, the second source electrode, and the second drain electrode are located on the second oxide semiconductor film. One of the first source electrode and the first drain electrode is electrically connected to the first electrode of the capacitor. The first gate electrode is electrically connected to the second gate electrode. One of the second source electrode and the second drain electrode is electrically connected to the fourth gate electrode. The second electrode of the capacitor is electrically connected to the first electrode of the light-emitting element. Furthermore, the first oxide semiconductor film and the second oxide semiconductor film at least partially overlap each other.

3. A semiconductor device comprising a pixel, the pixel comprising: First transistor; Second transistor; Capacitor; as well as Light-emitting elements The first transistor includes: First gate electrode; The first oxide semiconductor film on the first gate electrode; and The second gate electrode, the first source electrode, and the first drain electrode are on the first oxide semiconductor film. The second transistor includes: One of the first source electrode and the first drain electrode, which serves as the third gate electrode; The second oxide semiconductor film on the third gate electrode; and The fourth gate electrode, the second source electrode, and the second drain electrode are located on the second oxide semiconductor film. One of the first source electrode and the first drain electrode is electrically connected to the first electrode of the capacitor. The first gate electrode is electrically connected to the second gate electrode. One of the second source electrode and the second drain electrode is electrically connected to the fourth gate electrode. The second electrode of the capacitor is electrically connected to the first electrode of the light-emitting element. The first oxide semiconductor film and the second oxide semiconductor film at least partially overlap each other. The first oxide semiconductor film includes a first channel formation region. The second oxide semiconductor film includes a second channel formation region. Furthermore, the first channel forming region and the second channel forming region do not overlap with each other.

4. A semiconductor device comprising a pixel, the pixel comprising: First transistor; Second transistor; Capacitor; as well as Light-emitting elements The first transistor includes: First gate electrode; The first oxide semiconductor film on the first gate electrode; and The second gate electrode, the first source electrode, and the first drain electrode are on the first oxide semiconductor film. The second transistor includes: One of the first source electrode and the first drain electrode, which serves as the third gate electrode; The second oxide semiconductor film on the third gate electrode; and The fourth gate electrode, the second source electrode, and the second drain electrode are located on the second oxide semiconductor film. One of the first source electrode and the first drain electrode is electrically connected to the first electrode of the capacitor. The first gate electrode is electrically connected to the second gate electrode. One of the second source electrode and the second drain electrode is electrically connected to the fourth gate electrode. The second electrode of the capacitor is electrically connected to the first electrode of the light-emitting element. The first oxide semiconductor film and the second oxide semiconductor film at least partially overlap each other. One of the first source electrode and the first drain electrode is in contact with the first oxide semiconductor film through an opening, the opening being disposed in a first insulating film formed on the first oxide semiconductor film. Furthermore, the second oxide semiconductor film has a region that overlaps with the opening.

5. A semiconductor device comprising a pixel, the pixel comprising: First transistor; Second transistor; Capacitor; as well as Light-emitting elements The first transistor includes: First gate electrode; The first oxide semiconductor film on the first gate electrode; and The second gate electrode, the first source electrode, and the first drain electrode are on the first oxide semiconductor film. The second transistor includes: One of the first source electrode and the first drain electrode, which serves as the third gate electrode; The second oxide semiconductor film on the third gate electrode; and The fourth gate electrode, the second source electrode, and the second drain electrode are located on the second oxide semiconductor film. One of the first source electrode and the first drain electrode is electrically connected to the first electrode of the capacitor. The first gate electrode is electrically connected to the second gate electrode. One of the second source electrode and the second drain electrode is electrically connected to the fourth gate electrode. The second electrode of the capacitor is electrically connected to the first electrode of the light-emitting element. The first oxide semiconductor film and the second oxide semiconductor film at least partially overlap each other. The first oxide semiconductor film includes a first channel formation region. The second oxide semiconductor film includes a second channel formation region. The first channel formation region and the second channel formation region do not overlap. One of the first source electrode and the first drain electrode is in contact with the first oxide semiconductor film through an opening, the opening being disposed in a first insulating film formed on the first oxide semiconductor film. Furthermore, the second oxide semiconductor film has a region that overlaps with the opening.

6. A semiconductor device comprising a pixel, the pixel comprising: First transistor; Second transistor; Capacitor; as well as Light-emitting elements The first transistor includes: First gate electrode; The first oxide semiconductor film on the first gate electrode; and The second gate electrode, the first source electrode, and the first drain electrode are on the first oxide semiconductor film. The second transistor includes: One of the first source electrode and the first drain electrode, which serves as the third gate electrode; The second oxide semiconductor film on the third gate electrode; and The fourth gate electrode, the second source electrode, and the second drain electrode are located on the second oxide semiconductor film. One of the first source electrode and the first drain electrode is electrically connected to the first electrode of the capacitor. The first gate electrode is electrically connected to the second gate electrode. One of the second source electrode and the second drain electrode is electrically connected to the second electrode of the capacitor, the first electrode of the light-emitting element, and the fourth gate electrode. Furthermore, the first oxide semiconductor film and the second oxide semiconductor film at least partially overlap each other.

7. A semiconductor device comprising a pixel, the pixel comprising: First transistor; Second transistor; Capacitor; as well as Light-emitting elements The first transistor includes: First gate electrode; The first oxide semiconductor film on the first gate electrode; and The second gate electrode, the first source electrode, and the first drain electrode are on the first oxide semiconductor film. The second transistor includes: One of the first source electrode and the first drain electrode, which serves as the third gate electrode; The second oxide semiconductor film on the third gate electrode; and The fourth gate electrode, the second source electrode, and the second drain electrode are located on the second oxide semiconductor film. One of the first source electrode and the first drain electrode is electrically connected to the first electrode of the capacitor. The first gate electrode is electrically connected to the second gate electrode. One of the second source electrode and the second drain electrode is electrically connected to the second electrode of the capacitor, the first electrode of the light-emitting element, and the fourth gate electrode. The first oxide semiconductor film and the second oxide semiconductor film at least partially overlap each other. The first oxide semiconductor film includes a first channel formation region. The second oxide semiconductor film includes a second channel formation region. Furthermore, the first channel forming region and the second channel forming region do not overlap with each other.

8. A semiconductor device comprising a pixel, the pixel comprising: First transistor; Second transistor; Capacitor; as well as Light-emitting elements The first transistor includes: First gate electrode; The first oxide semiconductor film on the first gate electrode; and The second gate electrode, the first source electrode, and the first drain electrode are on the first oxide semiconductor film. The second transistor includes: One of the first source electrode and the first drain electrode, which serves as the third gate electrode; The second oxide semiconductor film on the third gate electrode; and The fourth gate electrode, the second source electrode, and the second drain electrode are located on the second oxide semiconductor film. One of the first source electrode and the first drain electrode is electrically connected to the first electrode of the capacitor. The first gate electrode is electrically connected to the second gate electrode. One of the second source electrode and the second drain electrode is electrically connected to the second electrode of the capacitor, the first electrode of the light-emitting element, and the fourth gate electrode. The first oxide semiconductor film and the second oxide semiconductor film at least partially overlap each other. One of the first source electrode and the first drain electrode is in contact with the first oxide semiconductor film through an opening, the opening being disposed in a first insulating film formed on the first oxide semiconductor film. Furthermore, the second oxide semiconductor film has a region that overlaps with the opening.

9. A semiconductor device comprising a pixel, the pixel comprising: First transistor; Second transistor; Capacitor; as well as Light-emitting elements The first transistor includes: First gate electrode; The first oxide semiconductor film on the first gate electrode; and The second gate electrode, the first source electrode, and the first drain electrode are on the first oxide semiconductor film. The second transistor includes: One of the first source electrode and the first drain electrode, which serves as the third gate electrode; The second oxide semiconductor film on the third gate electrode; and The fourth gate electrode, the second source electrode, and the second drain electrode are located on the second oxide semiconductor film. One of the first source electrode and the first drain electrode is electrically connected to the first electrode of the capacitor. The first gate electrode is electrically connected to the second gate electrode. One of the second source electrode and the second drain electrode is electrically connected to the second electrode of the capacitor, the first electrode of the light-emitting element, and the fourth gate electrode. The first oxide semiconductor film and the second oxide semiconductor film at least partially overlap each other. The first oxide semiconductor film includes a first channel formation region. The second oxide semiconductor film includes a second channel formation region. The first channel formation region and the second channel formation region do not overlap. One of the first source electrode and the first drain electrode is in contact with the first oxide semiconductor film through an opening, the opening being disposed in a first insulating film formed on the first oxide semiconductor film. Furthermore, the second oxide semiconductor film has a region that overlaps with the opening.

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