Semiconductor device, display device including the semiconductor device

Abstract

A novel semiconductor device is provided. The semiconductor device includes: a first transistor; and a second transistor. The first transistor includes: a first gate electrode; a first insulating film on the first gate electrode; a first oxide semiconductor film on the first insulating film; a first source electrode and a first drain electrode on the first oxide semiconductor film; a second insulating film on the first oxide semiconductor film, the first source electrode, and the first drain electrode; and a second gate electrode on the second insulating film. The second transistor includes: a first drain electrode; a second insulating film on the first drain electrode; a second oxide semiconductor film on the second insulating film; a second source electrode and a second drain electrode on the second oxide semiconductor film; a third insulating film on the second oxide semiconductor film, the second source electrode, and the second drain electrode; and a third gate electrode on 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. 2015194577 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 aspect of the present invention is a semiconductor device including a first transistor and a second transistor. The first transistor includes: a first gate electrode; a first insulating film on the first gate electrode; a first oxide semiconductor film on the first insulating film; a first source electrode on the first oxide semiconductor film; a first drain electrode on the first oxide semiconductor film; a second insulating film on the first oxide semiconductor film, the first source electrode, and the first drain electrode; and a second gate electrode on the second insulating film. The second transistor includes: a third gate electrode on the first insulating film; a second insulating film on the third gate electrode; a second oxide semiconductor film on the second insulating film including a channel region, a source region, and a drain region; a third insulating film contacting the channel region; a fourth gate electrode contacting the third insulating film; a fourth insulating film contacting 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.

[0016] In the above-described manner, it is preferred that the first gate electrode and the second gate electrode are connected together in the openings of the first insulating film and the second insulating film, and have a region located outside the side end of the first oxide semiconductor film.

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

[0018] In the above method, it is preferred that the atomic number ratio is around 4:2:3, and when In is 4, M is 1.5 or more and 2.5 or less, and Zn is 2 or more and 4 or less.

[0019] In the above-described manner, preferably, one or both of the first oxide semiconductor film and the second oxide semiconductor film include a crystalline portion having a c-axis orientation.

[0020] Another aspect of the present invention 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 on the first oxide semiconductor film; a first conductive film having a region overlapping the first insulating film and the first oxide semiconductor film with respect to it; a first oxide semiconductor film and a second insulating film on the first conductive film; a second conductive film on the first oxide semiconductor film; a third conductive film on the first oxide semiconductor film; and a third insulating film on the first oxide semiconductor film, the second conductive film, and the third conductive film. The second transistor includes: a third conductive film; a third insulating film on the third conductive film; a second oxide semiconductor film on the third insulating film; a fourth conductive film on the second oxide semiconductor film; and a fifth conductive film on 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.

[0021] Another aspect of the present invention 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 on the first oxide semiconductor film; a first conductive film having a region overlapping the first insulating film and the first oxide semiconductor film with respect to it; a first oxide semiconductor film and a second insulating film on the first conductive film; a second conductive film on the first oxide semiconductor film; a third conductive film on the first oxide semiconductor film; and a third insulating film on the first oxide semiconductor film, the second conductive film, and the third conductive film. The second transistor includes: a third conductive film; a third insulating film on the third conductive film; a second oxide semiconductor film on the third insulating film; a fourth conductive film on the second oxide semiconductor film; a fifth conductive film on the second oxide semiconductor film; a fourth insulating film on the second oxide semiconductor film, the fourth conductive film, and the fifth conductive film; and a sixth conductive film having a region overlapping the fourth insulating film and the second oxide semiconductor film with respect to it with respect to it. 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.

[0022] Another aspect of the present invention 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 on the first oxide semiconductor film; a first conductive film having a region overlapping the first insulating film and the first oxide semiconductor film with respect to it; a first oxide semiconductor film and a second insulating film on the first conductive film; a second conductive film on the first oxide semiconductor film; a third conductive film on the first oxide semiconductor film; and a third insulating film on 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: a third conductive film; a third insulating film on the third conductive film; a second oxide semiconductor film on the third insulating film; a fourth conductive film on the second oxide semiconductor film; a fifth conductive film on the second oxide semiconductor film; a fourth insulating film on the second oxide semiconductor film; a sixth conductive film having a region overlapping the fourth insulating film and the second oxide semiconductor film with respect to it; and a fifth insulating film on 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.

[0023] In the above-described manner, it is preferred that the first oxide semiconductor film and / or the second oxide semiconductor film comprise In, M (M is Al, Ga, Y or Sn) and Zn.

[0024] In the above-described manner, it is preferable that the atomic ratio of the oxide semiconductor film is approximately In:M:Zn = 4:2:3, and when In is 4, M is 1.5 or more and 2.5 or less, and Zn is 2 or more and 4 or less.

[0025] In the above-described manner, it is preferred that the first oxide semiconductor film and / or the second oxide semiconductor film include a crystalline portion having a c-axis orientation.

[0026] Another aspect of the present invention is a display device comprising: a semiconductor device as described in any of the above embodiments; and a light-emitting element. Preferably, the light-emitting element comprises an organic compound, wherein the organic compound comprises a polymeric compound.

[0027] Another aspect of the invention is a display module including the aforementioned display device and touch sensor. Another aspect of the invention is an electronic device comprising: any of the semiconductor devices described above, the aforementioned display device or the aforementioned display module; and operation keys or a battery.

[0028] According to one aspect of the present invention, a semiconductor device having multiple transistors stacked with a relatively small number of masks or manufacturing steps can be provided. According to one aspect of the present invention, a semiconductor device having multiple transistors having an oxide semiconductor film stacked with a relatively small number of masks or manufacturing steps can be provided. According to one aspect of the present invention, a novel semiconductor device can be provided.

[0029] Note that the description of these effects does not preclude the existence of other effects. One aspect of the invention does not require achieving all of the above-described effects. Effects other than these are obvious from the description, drawings, claims, etc., and effects other than those described above can be extracted from the description, drawings, claims, etc. Attached Figure Description

[0030] FIG. 1A and FIG. 1B These are top views and cross-sectional views of a semiconductor device;

[0031] FIG. 2 Explain the circuit of the semiconductor device;

[0032] FIG. 3 This is a cross-sectional view of a semiconductor device;

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

[0034] FIG. 5 This is a cross-sectional view of a semiconductor device;

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

[0036] FIG. 7A and FIG. 7B Explanation: It can carry a band;

[0037] FIG. 8A and FIG. 8B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0038] FIG. 9A and FIG. 9B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0039] FIG. 10A and FIG. 10B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0040] FIG. 11A and FIG. 11B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0041] FIG. 12A and FIG. 12B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0042] FIG. 13A and FIG. 13B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0043] FIG. 14A and FIG. 14B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0044] FIG. 15A and FIG. 15B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0045] FIG. 16A and FIG. 16B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0046] FIG. 17A and FIG. 17B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0047] FIG. 18A and FIG. 18B These are top views and cross-sectional views illustrating a semiconductor device;

[0048] FIG. 19A and FIG. 19B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0049] FIG. 20A and FIG. 20B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0050] FIG. 21A and FIG. 21B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0051] FIG. 22A and FIG. 22B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0052] FIG. 23A and FIG. 23B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0053] FIG. 24A and FIG. 24B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0054] FIG. 25A andFIG. 25B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0055] FIG. 26A and FIG. 26B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0056] FIG. 27A and FIG. 27B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0057] FIG. 28A and FIG. 28B These are top views and cross-sectional views illustrating a semiconductor device;

[0058] FIG. 29A and FIG. 29B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0059] FIG. 30A and FIG. 30B These are top views and cross-sectional views illustrating a semiconductor device;

[0060] FIG. 31 Explain the circuit of the semiconductor device;

[0061] FIG. 32 This is a cross-sectional view of a semiconductor device;

[0062] FIG. 33 This is a cross-sectional view of a semiconductor device;

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

[0064] FIG. 35A and FIG. 35B Explanation: It can carry a band;

[0065] FIG. 36A and FIG. 36B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0066] FIG. 37A and FIG. 37B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0067] FIG. 38A and FIG. 38B These are top views and cross-sectional views illustrating a semiconductor device;

[0068] FIG. 39A and FIG. 39B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0069] FIG. 40A and FIG. 40B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0070] FIG. 41A and FIG. 41B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0071] FIG. 42A and FIG. 42B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0072] FIG. 43A and FIG. 43B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0073] FIG. 44A and FIG. 44B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0074] FIG. 45A and FIG. 45B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0075] FIG. 46A and FIG. 46B It is a diagram illustrating the top surface and cross-section of a semiconductor device;

[0076] FIG. 47A and FIG. 47B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0077] FIG. 48A and FIG. 48B These are top views and cross-sectional views illustrating a semiconductor device;

[0078] FIG. 49A and FIG. 49B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0079] FIG. 50A and FIG. 50B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0080] FIG. 51A and FIG. 51B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0081] FIG. 52A and FIG. 52B These are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0082] FIG. 53A and FIG. 53BThese are top views and cross-sectional views illustrating the manufacturing process of semiconductor devices;

[0083] FIG. 54 This is a cross-sectional schematic diagram of the light-emitting element;

[0084] FIGS. 55A-55D This is a cross-sectional schematic diagram illustrating the manufacturing method of the EL layer;

[0085] FIG. 56 This is a schematic diagram illustrating a droplet ejection device;

[0086] FIGS. 57A-57C This shows the range of the atomic number ratio in oxide semiconductors;

[0087] FIG. 58 This is a diagram illustrating the crystal structure of InMZnO4;

[0088] FIG. 59 This is a diagram illustrating the energy band structure of a transistor using oxide semiconductors in the channel region;

[0089] FIGS. 60A-60E The diagram shows the structure analysis of CAAC-OS and single-crystal oxide semiconductors using XRD, as well as the selected area electron diffraction pattern of CAAC-OS.

[0090] FIGS. 61A-61E The image shows a cross-sectional TEM image, a planar TEM image, and an image obtained through image analysis of CAAC-OS.

[0091] FIGS. 62A-62D The electron diffraction pattern of nc-OS and the cross-sectional TEM image are shown.

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

[0093] FIG. 64 This shows the changes in the crystal structure caused by electron irradiation of In-Ga-Zn oxides;

[0094] FIG. 65 This is a top view showing one manner of displaying the device;

[0095] FIG. 66 This is a cross-sectional view showing one configuration of the display device;

[0096] FIG. 67 A cross-sectional view showing one configuration of the display device;

[0097] FIG. 68 This is a block diagram illustrating the display device;

[0098] FIG. 69 Description of the display module;

[0099] FIGS. 70A-70E Describe electronic devices;

[0100] FIGS. 71A-71G Describe electronic devices;

[0101] FIG. 72A and FIG. 72B It is a three-dimensional diagram illustrating the display device. Detailed Implementation

[0102] The embodiments will now be described with reference to the accompanying drawings. Note that the embodiments can be implemented in many different forms. Those skilled in the art will readily understand that the methods and details can be varied in many ways without departing from the spirit and scope of the invention. Therefore, the invention should not be construed as being limited to the contents described in the following embodiments.

[0103] In the accompanying drawings, the size of the constituent elements, the thickness of the layers, or the area are sometimes exaggerated for clarity. Therefore, one aspect of the invention is not necessarily limited to these dimensions. Furthermore, the drawings schematically illustrate ideal examples, and one aspect of the invention is not limited to the shapes or values ​​shown in the drawings.

[0104] The ordinal numbers “first,” “second,” “third,” etc., used in this specification are included to avoid confusion among the constituent elements, not to limit the quantity.

[0105] In this specification, for convenience, terms such as "upper" and "lower" are used to indicate the arrangement and to illustrate the positional relationship of the constituent elements with reference to the accompanying drawings. The positional relationship of the constituent elements may be appropriately changed depending on the direction in which each constituent element is described. Therefore, the terminology used is not limited to that described in the specification and may be replaced as appropriate.

[0106] In this specification and the like, a transistor is a device that includes at least three terminals: a gate, a drain, and a source. A transistor has a channel region between the drain (drain terminal, drain region, or drain electrode) and the source (source terminal, source region, or source electrode), and current can flow through the drain, the channel region, and the source. Note that in this specification and the like, the channel region refers to the region through which current primarily flows.

[0107] In cases where transistors with opposite polarities are used or the current direction changes during circuit operation, the functions of the "source" and "drain" are sometimes interchanged. Therefore, in this specification, the "source" and "drain" can be interchanged.

[0108] In this specification, etc., "electrical connection" includes the case where constituent elements are connected together by a component having a certain electrical function. There are no particular limitations on the "component having a certain electrical function," as long as it enables the transmission and reception of electrical signals between the connected constituent elements. Examples of "components having a certain electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other components with various functions.

[0109] In this specification, "parallel" refers to a state in which the angle formed by two straight lines is greater than or equal to -10° and less than 10°, and therefore also includes a state in which the angle is greater than or equal to -5° and less than 5°. Similarly, "perpendicular" refers to a state in which the angle formed by two straight lines is greater than or equal to 80° and less than 100°, and therefore also includes a state in which the angle is greater than or equal to 85° and less than 95°.

[0110] In this specification and other materials, the terms "film" and "layer" may be used interchangeably. For example, "conductive layer" may sometimes be referred to as "conductive film." Similarly, "insulating film" may sometimes be referred to as "insulating layer."

[0111] In this specification, unless otherwise specified, the off-state current refers to the drain current when the transistor is in the off state (also known as the non-conducting state or the blocked state). Unless otherwise specified, the off state of an n-channel transistor refers to the voltage between the gate and source (Vo). gs Gate-source voltage (V) is lower than the threshold voltage. th The off state of a p-channel transistor refers to the voltage V between the gate and source. gs Above the threshold voltage V th The state of an n-channel transistor. For example, the off-state current of an n-channel transistor sometimes refers to the gate-source voltage Vo. gs Below the threshold voltage V th The drain current at that time.

[0112] The off-state current of a transistor sometimes depends on V. gs Therefore, "the off-state current of a transistor is less than I" sometimes refers to the existence of a V such that the off-state current of the transistor is less than I. gs The off-state current of a transistor sometimes refers to a predetermined V. gs The closed state in the middle, V within the predetermined range gs The off state or V that can achieve a sufficiently low off-state current. gs The off-state current is equal to the off-state current in the closed state.

[0113] As an example, consider an n-channel transistor with a threshold voltage V. th 0.5V, V gsThe drain current at 0.5V is 1×10 -9 A, V gs The drain current at 0.1V is 1×10 -13 A, V gs The drain current at -0.5V is 1×10⁻⁶. -19 A, V gs The drain current at -0.8V is 1×10 -22 A. In V gs When it is -0.5V or V gs The drain current of this transistor is 1 × 10⁻⁶ V within the range of -0.5V to -0.8V. -19 The current is below A, so the off-state current of this transistor is sometimes referred to as 1 × 10⁻⁶. -19 Below A. This is because the drain current of this transistor is 1 × 10⁻⁶. -22 V below A gs Therefore, the off-state current of this transistor is sometimes referred to as 1 × 10⁻⁶. -22 Below A.

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

[0115] The off-state current of a transistor sometimes depends on temperature. In this specification, unless otherwise specified, the off-state current may refer to the off-state current at room temperature, 60°C, 85°C, 95°C, or 125°C. Alternatively, the off-state current may refer to the off-state current at a temperature that ensures the reliability of the semiconductor device including the transistor, or at a temperature in which the semiconductor device including the transistor is used (e.g., a temperature range of 5°C to 35°C). A transistor's off-state current of I or less means that at room temperature, 60°C, 85°C, 95°C, 125°C, a temperature that ensures the reliability of the semiconductor device including the transistor, or at a temperature in which the semiconductor device is used (e.g., a temperature range of 5°C to 35°C), there exists a V that causes the transistor's off-state current to be I or less. gs .

[0116] The off-state current of a transistor sometimes depends on the voltage V between the drain and source. ds In this specification, unless otherwise specified, the off-state current is sometimes V. dsThe off-state current is 0.1V, 0.8V, 1V, 1.2V, 1.8V, 2.5V, 3V, 3.3V, 10V, 12V, 16V, or 20V. Alternatively, the off-state current is sometimes a V that ensures the reliability of the semiconductor device including the transistor. ds Or the V used in the semiconductor device, etc. ds The off-state current of a transistor is below I, meaning that when the transistor's off-state current is below V... ds The voltage ratings are 0.1V, 0.8V, 1V, 1.2V, 1.8V, 2.5V, 3V, 3.3V, 10V, 12V, 16V, and 20V, ensuring the reliability of semiconductor devices including this transistor. ds Or the V used in the semiconductor device, etc. ds Below, there exists a V such that the off-state current of the transistor is less than or equal to I. gs .

[0117] In the above explanation of off-state current, the drain can be referred to as the source. That is to say, off-state current sometimes refers to the current flowing through the source when the transistor is in the off state.

[0118] In this specification, etc., "leakage current" is sometimes used to mean the same thing as off-state current. In this specification, off-state current sometimes refers to the current flowing between the source and drain when the transistor is in the off state.

[0119] In this specification, the threshold voltage of a transistor refers to the gate voltage (V) at which a channel is formed in the transistor. g Specifically, in a graph where the gate voltage (Vg) is represented on the horizontal axis and the square root of the drain current (Id) is represented on the vertical axis, the threshold voltage of a transistor is sometimes referred to as the straight line extrapolated from the tangent with the maximum slope in the plotted curve (Vg-√Id characteristic) to the drain current (Id). d The gate voltage (V) at the crossover point where the square root of ) is 0 (Id is 0A) g Alternatively, the threshold voltage of a transistor sometimes refers to the voltage at which the channel length L is equal to the channel width W, and the voltage I... d The value of [A]×L[μm] / W[μm] is 1×10 -9 Gate voltage (V) at [A] g ).

[0120] In this specification, for example, when the conductivity is sufficiently low, a "semiconductor" sometimes exhibits the characteristics of an "insulator." Furthermore, the boundary between a "semiconductor" and an "insulator" is not always clear, so it is sometimes impossible to precisely distinguish between them. Therefore, "semiconductor" in this specification may sometimes be replaced with "insulator." Similarly, "insulator" in this specification may sometimes be replaced with "semiconductor." Additionally, "insulator" in this specification may sometimes be replaced with "semi-insulator."

[0121] In this specification, for example, when the conductivity is sufficiently high, a "semiconductor" sometimes exhibits the characteristics of a "conductor". Furthermore, the boundary between a "semiconductor" and a "conductor" is not always clear, and therefore, it is sometimes impossible to precisely distinguish between them. Therefore, in this specification, "semiconductor" may sometimes be replaced with "conductor". Similarly, in this specification, "conductor" may sometimes be replaced with "semiconductor".

[0122] In this specification, impurities in a semiconductor refer to elements other than the main components of the semiconductor. For example, elements with a concentration of less than 0.1 atomic% are considered impurities. If a semiconductor contains impurities, it is possible for a density of states (DOS) to form in the semiconductor, carrier mobility may decrease, or crystallinity may decrease. When the semiconductor contains oxide semiconductors, examples of impurities that alter semiconductor properties include Group 1 elements, Group 2 elements, Group 14 elements, Group 15 elements, and transition metals other than the main components. Typical examples include hydrogen (found in water), lithium, sodium, silicon, boron, phosphorus, carbon, and nitrogen. In oxide semiconductors, oxygen defects sometimes occur due to the incorporation of impurities such as hydrogen. Furthermore, when the semiconductor contains silicon, examples of impurities that alter semiconductor properties include oxygen, Group 1 elements (excluding hydrogen), Group 2 elements, Group 13 elements, and Group 15 elements.

[0123] Implementation Method 1

[0124] In this embodiment, refer to FIG. 1A and FIGS. 1B-17A and FIG. 17B A semiconductor device and a method for manufacturing a semiconductor device according to one aspect of the present invention will be described.

[0125] <1-1. Example 1 of the structure of a semiconductor device>

[0126] FIG. 1A This is a top view of a semiconductor device 100 according to one aspect of the present invention. FIG. 1B It is along FIG. 1A The cross-sectional view of the dashed-dot line A1-A2 in the diagram. Furthermore, FIG. 1BThis includes the cross-section of transistor Tr1 along the channel length (L) and the cross-section of transistor Tr2 along the channel length (L).

[0127] In addition, FIG. 1A For convenience, some components of the semiconductor device 100 (e.g., the insulating film used as a gate insulating film) and some of the symbols for the components are not shown. Note that in the subsequent top view of the semiconductor device, sometimes... FIG. 1A Similarly, neither part of the constituent elements nor part of the symbols of the constituent elements are shown.

[0128] FIG. 1A and FIG. 1B The semiconductor device 100 shown includes: a transistor Tr1; and a transistor Tr2, at least a portion of which overlaps with transistor Tr1. Furthermore, transistors Tr1 and Tr2 are bottom-gate transistors.

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

[0130] Transistor Tr1 includes: a conductive film 104 on substrate 102; an insulating film 106 on substrate 102 and conductive film 104; an oxide semiconductor film 108 on insulating film 106; a conductive film 112a on oxide semiconductor film 108; a conductive film 112b on oxide semiconductor film 108; an insulating film 114 on oxide semiconductor film 108, conductive film 112a and conductive film 112b; an insulating film 116 on insulating film 114; and a conductive film 122c on insulating film 116.

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

[0132] like FIG. 1A and FIG. 1B As shown, oxide semiconductor film 108 and oxide semiconductor film 128 partially overlap each other. Additionally, as... FIG. 1A and FIG. 1BAs shown, preferably, the channel region formed in the oxide semiconductor film 108 of transistor Tr1 does not overlap with the channel region formed in the oxide semiconductor film 128 of transistor Tr2.

[0133] If the channel regions of transistor Tr1 and transistor Tr2 overlap, one transistor may sometimes affect the other during operation. To avoid this negative impact, structures that increase the spacing between transistors Tr1 and Tr2, or structures that provide a conductive film between transistors Tr1 and Tr2, can be used. However, using the former structure increases the thickness of the semiconductor device. Therefore, problems such as bendability may occur, for example, when forming the semiconductor device 100 on a flexible substrate. Using the latter structure involves the need for a conductive film formation process and an increase in the thickness of the semiconductor device.

[0134] On the other hand, in one embodiment of the semiconductor device 100 of the present invention, transistor Tr1 and transistor Tr2 overlap, and the channel regions of each transistor do not overlap. Furthermore, since portions of the oxide semiconductor films forming the channel regions overlap, the area of ​​the transistors can be appropriately reduced.

[0135] Furthermore, both oxide semiconductor films 108 and 128 contain In, M (where M is Al, Ga, Y, or Sn), and Zn. For example, oxide semiconductor films 108 and 128 preferably have regions where the atomic ratio of In is greater than the atomic ratio of M. Note that the semiconductor devices of one aspect of the present invention are not limited thereto; they may have regions where the atomic ratio of In is less than the atomic ratio of M, or they may have regions where the atomic ratio of In is equal to the atomic ratio of M.

[0136] Preferably, the composition of the oxide semiconductor film 108 is the same as or substantially the same as the composition 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, manufacturing costs can be reduced. Note that the semiconductor device of one embodiment of the present invention is not limited thereto, and the compositions of the oxide semiconductor film 108 and the oxide semiconductor film 128 may also be different from each other.

[0137] When both oxide semiconductor films 108 and 128 have regions where the ratio of In atoms is greater than the ratio of M atoms, the field-effect mobility of transistors Tr1 and Tr2 can be improved. 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.

[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] FIG. 1A and FIG. 1B The semiconductor device 100 shown can be suitably used in the pixel circuit of a display device. FIG. 1A and FIG. 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... FIG. 2 and FIG. 1A 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 FIG. 1B To the general FIG. 2 and FIG. 2 An example of the semiconductor device 100 being used in the pixel circuit of a display device will be described.

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

[0143] FIG. 1A The semiconductor device 100 shown includes: transistor Tr1; transistor Tr2; capacitor Cs1; and light-emitting element 160. Note that... FIG. 1B 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 FIG. 2 and FIG. 1A 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] FIG. 1BThe 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 FIG. 1A and FIG. 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 FIG. 1A and FIG. 1B The semiconductor device 100 shown will be described in detail. FIG. 1A and FIG. 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... FIG. 1A and FIG. 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 FIG. 3 and FIG. 3 As shown, both transistors Tr1 and Tr2 include two gate electrodes.

[0160] Here, refer to FIG. 1A and FIG. 3 as well as FIG. 3 The effects of the two gate electrodes are explained.

[0161] also, FIG. 3 It is along FIG. 1B The cross-sectional view of the dotted-dash line B1-B2. FIG. 4A This includes the cross-section along the channel width (W) direction of transistor Tr1.

[0162] like FIG. 4B As shown, 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. Therefore, the conductive film 104 and the conductive film 122c are supplied with the same potential. Furthermore, as... FIG. 5 As shown, the oxide semiconductor film 108 is located opposite to the conductive films 104 and 122c, and is sandwiched between the conductive films used as two gate electrodes. The channel width lengths of both the conductive films 104 and 122c are greater than the channel width length of the oxide semiconductor film 108. The oxide semiconductor film 108 overlaps with the conductive films 104 and 122c entirely through insulating films 106, 114, and 116.

[0163] In other words, conductive film 104 and conductive film 122c are connected in an opening 181 provided in insulating films 106, 114, 116, and have a region located outside the side end of oxide semiconductor film 108.

[0164] By employing the above structure, the electric fields of conductive film 104 and conductive film 122c can be used to surround the oxide semiconductor film 108 included in transistor Tr1. The device structure of a transistor, such as transistor Tr1, in which the electric fields of the first gate electrode and the second gate electrode surround the oxide semiconductor film forming the channel region is called a surrounded channel (S-channel) structure.

[0165] Because transistor Tr1 has an S-channel structure, an electric field for inducing a channel can be effectively applied to the oxide semiconductor film 108 using the conductive film 104, which serves as the first gate electrode. This improves the current-driving capability of transistor Tr1, resulting in high on-state current characteristics. Furthermore, since the on-state current can be increased, the size of transistor Tr1 can be reduced. Additionally, because transistor Tr1 has a structure in which the oxide semiconductor film 108 is surrounded by the conductive film 104, which serves as the first gate electrode, and the conductive film 122c, which serves as the second gate electrode, the mechanical strength of transistor Tr1 can be improved.

[0166] Although the structure connecting the first gate electrode and the second gate electrode has been described above, the invention is not limited to this. For example, as FIG. 1A As shown in transistor Tr2, the conductive film 130, which is used as the second gate electrode, can also be electrically connected to the conductive film 122a, which is used as the source electrode or drain electrode of transistor Tr2.

[0167] <1-5. Components of a Semiconductor Device>

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

[0169] [Substrate]

[0170] There are no particular restrictions on the material of substrate 102, as long as it is a heat-resistant material capable of withstanding subsequent heat treatment. For example, glass substrates, ceramic substrates, quartz substrates, and sapphire substrates can be used as substrate 102. Substrate 102 can also be a single-crystal semiconductor substrate or a polycrystalline semiconductor substrate made of silicon or silicon carbide, a compound semiconductor substrate made of silicon-germanium, or an SOI (silicon-on-insulator) substrate. Substrates on which semiconductor elements are disposed can also be used as substrate 102. When a glass substrate is used as substrate 102, large-scale display devices can be manufactured using glass substrates of the following sizes: 6th generation (1500mm × 1850mm), 7th generation (1870mm × 2200mm), 8th generation (2200mm × 2400mm), 9th generation (2400mm × 2800mm), and 10th generation (2950mm × 3400mm).

[0171] A flexible substrate can also be used as substrate 102, and the semiconductor device 100 can be directly disposed on the flexible substrate. Alternatively, a release layer can be disposed between substrate 102 and semiconductor device 100. The release layer can be used when a portion or all of the semiconductor device formed on the release layer is separated from substrate 102 and transferred to another substrate. In this case, semiconductor device 100 can be transferred to a substrate with low heat resistance or a flexible substrate.

[0172] <Conductive film>

[0173] Conductive films 104, 112a, 112b, 122a, 122b, 122c, 130, 138, and 144 may be formed using metallic elements 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), and cobalt (Co), alloys containing the above-mentioned metallic elements as components, or alloys containing combinations of the above-mentioned metallic elements.

[0174] Conductive films 104, 112a, 112b, 122a, 122b, 122c, 130, 138, and 144 may be formed using oxide conductors such as oxides containing indium and tin, oxides containing tungsten and indium, oxides containing tungsten, indium, and zinc, oxides containing titanium and indium, oxides containing titanium, indium, and tin, oxides containing indium and zinc, oxides containing silicon, indium, and tin, and oxides containing indium, gallium, and zinc.

[0175] In particular, the aforementioned oxide conductor is applicable to the conductive film 130. Here, the oxide conductor will be described. In this specification, the oxide conductor may also be referred to as an OC (oxide conductor). For example, an oxide conductor is obtained by forming oxygen vacancies in an oxide semiconductor and then adding hydrogen to these oxygen vacancies to form donor levels near the conduction band. As a result, the conductivity of the oxide semiconductor increases, thus becoming a conductor. Oxide semiconductors that can become conductors are called oxide conductors. Generally, because oxide semiconductors have a large band gap, visible light is transmitted through them. An oxide conductor is an oxide semiconductor with donor levels near the conduction band. Therefore, the effect of absorption due to donor levels is small in an oxide conductor, and thus, the oxide conductor has visible light transmittance equivalent to that of an oxide semiconductor.

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

[0177] In particular, the above-mentioned Cu-X alloy film is applicable to one or more of conductive films 104, 112a, 112b, 122a, 122b, and 122c. As a Cu-X alloy film, a Cu-Mn alloy film is particularly preferred.

[0178] The materials used as one or more of the conductive films 104, 112a, 112b, 122a, 122b and 122c are particularly preferably one or more of the aforementioned metallic elements, namely aluminum, copper, titanium, tungsten, tantalum and molybdenum.

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

[0180] [Insulating film]

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

[0182] The insulating film 106 is used as a barrier film to inhibit oxygen permeation. For example, when one or more of the insulating films 114, 116, 108, 128, 124, and 126 have excess oxygen regions, the insulating film 106 can inhibit oxygen permeation.

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

[0184] For example, excess oxygen regions in an oxide insulating film can be formed by: forming the insulating film in an oxygen atmosphere; heating the insulating film in an oxygen atmosphere after its formation; or adding oxygen to the insulating film after its formation. Plasma treatment is preferred as a method for adding oxygen to the insulating film after film formation.

[0185] The insulating film used as the gate insulating film for transistors Tr1 and Tr2 can be formed using hafnium oxide. When hafnium oxide is used as the insulating film for the gate insulating film, the following effects are achieved.

[0186] Hafnium oxide has a higher relative permittivity than silicon oxide and silicon oxynitride. Therefore, the insulating film formed using hafnium oxide can be thicker than that formed using silicon oxide, thereby reducing leakage current caused by tunneling current. In other words, transistors with low off-state current can be manufactured. Furthermore, hafnium oxide with a crystalline structure has a higher relative permittivity than hafnium oxide with an amorphous structure. Therefore, hafnium oxide with a crystalline structure is preferred for manufacturing transistors with low off-state current. Examples of crystalline structures include monoclinic and cubic crystal systems. Note that one aspect of the invention is not limited to the above examples.

[0187] The insulating film used as the gate insulating film for transistors Tr1 and Tr2 can be formed using silicon nitride. When silicon nitride is used as the insulating film for the gate, the following effects are achieved: Compared to silicon oxide, silicon nitride has a higher relative permittivity and requires a larger thickness to obtain the same capacitance as silicon oxide. Therefore, the thickness of the gate insulating film can be increased. Consequently, electrostatic discharge (ESD) damage to transistors Tr1 and Tr2 can be prevented by suppressing the drop in dielectric breakdown voltage and increasing the dielectric breakdown voltage.

[0188] Insulating films 114, 116, 124, and 126 function to supply oxygen to oxide semiconductor film 108 and / or oxide semiconductor film 128. That is, insulating films 114, 116, 124, and 126 contain oxygen. Insulating films 114 and 124 are insulating films that allow oxygen to permeate. Note that insulating film 114 is also used as a film to mitigate damage to oxide semiconductor film 108 when insulating film 116 is formed in a subsequent process. Insulating film 124 is also used as a film to mitigate damage to oxide semiconductor film 128 when insulating film 126 is formed in a subsequent process.

[0189] As insulating films 114 and 124, silicon oxide films, silicon oxynitride films, etc., with a thickness of 5 nm or more and 150 nm or less can be used, preferably 5 nm or more and 50 nm or less.

[0190] Furthermore, it is preferable to have a low amount of defects in the insulating films 114 and 124. Typically, the spin density of the signal originating from silicon dangling bonds and appearing at g = 2.001, as measured by electron spin resonance (ESR), is preferably 3 × 10⁻⁶. 17 spins / cm 3 The reason is that if the defect density of insulating films 114 and 124 is high, oxygen will bond with the defect, thereby reducing the amount of oxygen permeating into insulating film 114.

[0191] Insulating films 114 and 124 can be formed using oxide insulating films that exhibit low density of states due to nitride oxides. Note that this density of states due to nitride oxides can sometimes be formed at the energy (E) at the valence band top of the oxide semiconductor film. V_OS ) and the energy at the bottom of the conduction band (E) C_OS Between ), and as the above-mentioned oxide insulating film, silicon oxynitride film with low nitrogen oxide emission, aluminum oxynitride film with low nitrogen oxide emission, etc., can be used.

[0192] Furthermore, in thermal desorption spectroscopy (TDS), silicon oxynitride films with low nitrogen oxide release are those with higher ammonia release than nitrogen oxide release, typically with an ammonia release of 1 × 10⁻⁶. 18 cm -3 Above and 5×10 19 cm -3 The following is a note: The ammonia release figures above refer to the total amount of ammonia released during heat treatment in TDS at temperatures ranging from 50°C to 650°C or from 50°C to 550°C. The ammonia release figures above are the total amount of ammonia released in TDS, converted to ammonia molecules.

[0193] Nitrogen oxides (NO) x (where x is greater than 0 and less than 2, preferably greater than 1 and less than 2), typically NO2 or NO forms energy levels in insulating films 114 and 124. These energy levels are located within the band gap of oxide semiconductor films 108 and 128. Therefore, when nitrogen oxides diffuse to the interface between insulating film 114 and oxide semiconductor film 108, or between insulating film 124 and oxide semiconductor film 128, electrons are sometimes trapped at this energy level on the insulating film 114 or 124 side. As a result, the trapped electrons remain near the interface between insulating film 114 and oxide semiconductor film 108, or near the interface between insulating film 124 and oxide semiconductor film 128, thereby causing the threshold voltage of the transistor to drift 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 nitrogen concentration of the aforementioned oxide insulating film, measured using SIMS, was 6 × 10⁻⁶. 20 atoms / cm 3 the following.

[0199] 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.

[0200] Insulating films 116 and 126 are formed using oxide insulating films with an oxygen content exceeding the stoichiometric composition. Upon heating, a portion of the oxygen is released from the oxide insulating film with the oxygen content exceeding the stoichiometric composition. The amount of oxygen released from the oxide insulating film with the oxygen content exceeding the stoichiometric composition is 1.0 × 10⁻⁶. 19 cm -3 The preferred value is 3.0 × 10⁴. 20 cm -3 That's all. Note that the oxygen release figures above refer to the total amount of oxygen released during heat treatment in TDS at temperatures ranging from 50°C to 650°C or from 50°C to 550°C. The oxygen release figures above are the total amount of oxygen released in TDS, converted to oxygen molecules.

[0201] The insulating films 116 and 126 can be silicon oxide films, silicon oxynitride films, etc., with a thickness of 30 nm or more and 500 nm or less, preferably 50 nm or more and 400 nm or less.

[0202] Furthermore, it is preferable to have a low amount of defects in the insulating films 116 and 126. Typically, the spin density of the signal originating from silicon dangling bonds and appearing at g = 2.001, as measured by ESR, is less than 1.5 × 10⁻⁶. 18 spins / cm 3 More preferably 1×10 18 spins / cm 3 the following.

[0203] Since insulating films 114 and 116, as well as insulating films 124 and 126, can be formed using insulating films containing the same type of material, the interfaces between insulating films 114 and 116 and between insulating films 124 and 126 are sometimes not clearly identifiable. Therefore, in this embodiment, the interfaces between insulating films 114 and 116 and between insulating films 124 and 126 are indicated by dashed lines.

[0204] Insulating film 134 is used as a protective insulating film for transistors Tr1 and Tr2.

[0205] The insulating film 134 contains one or both of hydrogen and nitrogen. Additionally, the insulating film 134 contains nitrogen and silicon. The insulating film 134 functions to block oxygen, hydrogen, water, alkali metals, alkaline earth metals, etc. By providing the insulating film 134, it is possible to prevent oxygen from diffusing from the oxide semiconductor films 108 and 128 to the outside, and it is also possible to prevent the oxygen contained in the insulating films 114, 116, 124, and 126 from diffusing to the outside. Furthermore, it is possible to prevent hydrogen, water, etc., from intruding into the oxide semiconductor films 108 and 128 from the outside.

[0206] The insulating film 134 can be formed, for example, using a nitride insulating film. This nitride insulating film is formed using silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, etc.

[0207] [Oxide semiconductor film]

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

[0209] When both oxide semiconductor films 108 and 128 contain In-M-Zn oxide, the atomic ratio of the metal elements in the sputtering target used to form the In-M-Zn oxide preferably satisfies In > M. For example, the atomic ratio of the metal elements in such a sputtering target is In:M:Zn = 2:1:3, In:M:Zn = 3:1:2, or In:M:Zn = 4:2:4.1.

[0210] When both oxide semiconductor film 108 and oxide semiconductor film 128 contain In-M-Zn oxide, the atomic ratio of the metal elements in the sputtering target used to form the In-M-Zn oxide preferably satisfies In ≤ M. For example, the atomic ratio of the metal elements in such a sputtering target is 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, In:M:Zn = 1:3:6.

[0211] When both oxide semiconductor films 108 and 128 are In-M-Zn oxides, a sputtering target containing polycrystalline In-M-Zn oxide is preferably used. By using a target containing polycrystalline In-M-Zn oxide, crystalline oxide semiconductor films 108 and 128 can be easily formed. Note that the atomic ratio of metal elements in the formed oxide semiconductor films 108 and 128 varies within ±40% of the atomic ratio of metal elements in the aforementioned sputtering target. For example, when a sputtering target with an In:Ga:Zn atomic ratio of 4:2:4.1 is used as the sputtering target for oxide semiconductor films 108 and 128, the In:Ga:Zn atomic ratio of oxide semiconductor films 108 and 128 is sometimes 4:2:3 or close to 4:2:3.

[0212] The band gaps of the oxide semiconductor films 108 and 128 are 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. By using such oxide semiconductors with wider band gaps, the off-state currents of transistors Tr1 and Tr2 can be reduced.

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

[0214] Hydrogen contained in oxide semiconductor films 108 and 128 reacts with oxygen bonded to metal atoms to form water, while oxygen defects are formed in the lattice (or the portion where oxygen desorption occurs) during this process. When hydrogen enters this oxygen defect, electrons are sometimes generated as charge carriers. Additionally, sometimes a portion of the hydrogen bonds with oxygen bonded to metal atoms, generating electrons as charge carriers. Therefore, transistors containing oxide semiconductor films containing hydrogen tend to have always-on characteristics. Thus, it is preferable to minimize the amount of hydrogen in oxide semiconductor films 108 and 128.

[0215] Specifically, in oxide semiconductor films 108 and 128, the hydrogen concentration measured using SIMS was 2 × 10⁻⁶. 20 atoms / cm 3 The following is preferred: 5×10 19 atoms / cm 3 Hereinafter, 1×10 is more preferred. 19 atoms / cm 3 The following is more preferably 5×10 18 atoms / cm 3 Hereinafter, 1×10 is more preferred. 18 atoms / cm 3 The following is more preferably 5×10 17 atoms / cm 3 Hereinafter, 1×10 is further preferred. 16 atoms / cm 3 the following.

[0216] When oxide semiconductor films 108 and 128 contain silicon or carbon, one of Group 14 elements, oxygen vacancies increase in oxide semiconductor films 108 and 128, making oxide semiconductor films 108 and 128 n-type films. Therefore, the silicon concentration in oxide semiconductor films 108 and 128, as measured by SIMS analysis, is 2 × 10⁻⁶. 18 atoms / cm 3 The following is preferred: 2×10 17 atoms / cm 3The carbon concentration in oxide semiconductor films 108 and 128, as determined by SIMS analysis, is 2 × 10⁻⁶. 18 atoms / cm 3 The following is preferred: 2×10 17 atoms / cm 3 the following.

[0217] Furthermore, the concentrations of alkali metals or alkaline earth metals in oxide semiconductor films 108 and 128, as determined by SIMS analysis, were 1 × 10⁻⁶. 18 atoms / cm 3 The following is preferred: 2×10 16 atoms / cm 3 The following applies. When alkali metals and alkaline earth metals bond with oxide semiconductors, charge carriers are sometimes generated, which increases the off-state current of the transistor. Therefore, it is preferable to reduce the concentration of alkali metals or alkaline earth metals in oxide semiconductor films 108 and 128.

[0218] The oxide semiconductor films 108 and 128 may, for example, have non-single-crystal structures. Examples of non-single-crystal structures include CAAC-OS (c-axis-aligned crystalline oxide semiconductor), polycrystalline structures, microcrystalline structures, and amorphous structures. Among non-single-crystal structures, amorphous structures have the highest defect state density, while CAAC-OS has the lowest defect state density.

[0219] The various films described above, such as conductive films, insulating films, and oxide semiconductor films, can be formed using sputtering, plasma-enhanced chemical vapor deposition (PECVD), and thermal CVD. Examples of thermal CVD include MOCVD (metal-organic chemical vapor deposition) and ALD (atomic layer deposition).

[0220] Thermal CVD is a film formation method that does not use plasma, thus having the advantage of not producing defects caused by plasma damage.

[0221] Film formation using thermal CVD can be performed by simultaneously supplying source gas and oxidant into the processing chamber, setting the pressure inside the processing chamber to atmospheric pressure or depressurization, so that the reaction occurs near or on the substrate.

[0222] Alternatively, film formation using the ALD method can be performed under the following conditions: the pressure inside the processing chamber is set to atmospheric pressure or reduced pressure, and a source gas is used for the reaction.

[0223] Various films, such as conductive films, insulating films, and oxide semiconductor films, as described in this embodiment can be formed using thermal CVD methods such as MOCVD or ALD. For example, the In-Ga-Zn-O film can be formed using trimethylindium, trimethylgallium, and dimethylzinc. The chemical formula of trimethylindium is In(CH3)3. The chemical formula of trimethylgallium is Ga(CH3)3. Additionally, the chemical formula of dimethylzinc is Zn(CH3)2. Not limited to the above combinations, triethylgallium (chemical formula: Ga(C2H5)3) can be used instead of trimethylgallium, and diethylzinc (chemical formula: Zn(C2H5)2) can be used instead of dimethylzinc.

[0224] For example, when forming a hafnium oxide film using an ALD (Alternating Discharge) method film-forming apparatus, two gases are used: ozone (O3) as an oxidant; and a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide, tetradimethylammonium hafnium (TDMAH), etc.). Furthermore, the chemical formula of tetradimethylammonium hafnium is Hf[N(CH3)2]4. As an example of other liquid materials, tetra(ethylmethylammonium)hafnium is also used.

[0225] For example, when forming an alumina film using an ALD (Alternating Dissolved Carbon) method film-forming apparatus, two gases are used: H₂O as an oxidant; and a source gas obtained by vaporizing a liquid containing a solvent and an aluminum precursor compound (e.g., trimethylaluminum (TMA)). Furthermore, the chemical formula of trimethylaluminum is Al(CH₃)₃. Examples of other liquid materials include tris(dimethylamide)aluminum, triisobutylaluminum, and aluminum tris(2,2,6,6-tetramethyl-3,5-heptadecane).

[0226] For example, when forming a silicon oxide film using an ALD film-forming apparatus, hexachlorosilane is attached to the film-forming surface to remove chlorine contained in the attachment, and free radicals of an oxidizing gas (e.g., O2, nitrous oxide) are supplied to react with the attachment.

[0227] For example, when forming a tungsten film using an ALD (Alternating Discharge) method film deposition apparatus, an initial tungsten film is formed using WF6 gas and B2H6 gas, and then the final tungsten film is formed using WF6 gas and H2 gas. Note that SiH4 gas can also be used instead of B2H6 gas.

[0228] 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.

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

[0230] Below, refer to FIG. 1B and FIG. 4A and FIG. 1B right FIG. 4B and FIG. 1B A modified example of the semiconductor device 100 shown will be described.

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

[0232] FIG. 4B The structure shown does not include a conductive film 122c that serves as the second gate electrode of the transistor Tr1 included in the semiconductor device 100.

[0233] FIG. 6A The diagram shows a structure without a conductive film 130, which is used as the second gate electrode of the transistor Tr2 included in the semiconductor device 100, and an insulating film 134 on the conductive film 130. Furthermore, in FIG. 6B In the structure shown, an opening 183 is formed in insulating films 124, 126, and 136 instead of opening 182 in insulating films 124 and 126, and opening 184 in insulating films 134 and 136. By employing a structure including an opening, manufacturing steps can be reduced, and therefore it is preferred.

[0234] FIG. 7A 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... FIG. 7B 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 FIG. 1A and FIG. 1B and FIG. 6A and FIG. 6B right FIG. 6A and FIG. 6B 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] FIG. 7A and FIG. 7B It is a cross-sectional view of the transistor Tr1 included in the semiconductor device 100 along the channel length (L) direction.

[0239] FIG. 7A 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] FIG. 7B 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] FIG. 7A and FIG. 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] FIG. 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. FIG. 7BAn example of an energy band diagram along the film thickness direction is shown, the stack having an insulating film 106, oxide semiconductor films 108b, 108c, and an insulating film 114. For ease of understanding, the energy levels (Ec) of the conduction band bottoms of the insulating films 106, 108b, 108c, and 114 are shown in the energy band diagram.

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

[0244] FIG. 7B The energy band diagram is as follows: silicon oxide films are used as insulating films 106 and 114; oxide semiconductor films 108b are formed using metal oxide targets with an atomic ratio of In:Ga:Zn = 4:2:4.1; and oxide semiconductor films 108c are formed using metal oxide targets with an atomic ratio of In:Ga:Zn = 1:3:2.

[0245] like FIG. 6A and FIG. 6B As shown, the energy levels at the bottom of the conduction band change smoothly between oxide semiconductor films 108a and 108b, and between oxide semiconductor films 108b and 108c. In other words, the energy levels at the bottom of the conduction band change continuously or are continuously joined. To achieve such a band structure, impurities that could form defect energy levels such as trap centers or recombination centers must not exist at the interfaces between oxide semiconductor films 108a and 108b, or between oxide semiconductor films 108b and 108c.

[0246] In order to form a continuous bond between oxide semiconductor films 108a and 108b and between oxide semiconductor films 108b and 108c, a multi-chamber film deposition apparatus (sputtering apparatus) equipped with a lock-up chamber is used to continuously stack the films in such a way that the films are not exposed to the atmosphere.

[0247] By adopting FIG. 8A and FIGS. 8B-17AIn the band structure, the oxide semiconductor film 108b becomes a well. In the transistor using the above-described stacked structure, the channel region is formed in the oxide semiconductor film 108b.

[0248] By setting oxide semiconductor film 108a and / or oxide semiconductor film 108c, oxide semiconductor film 108b can be moved away from the trap energy level.

[0249] Furthermore, 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 the channel region, and electrons tend to accumulate in the trap level. When electrons accumulate in the trap level, they become negative fixed charges, causing the threshold voltage of the transistor to drift in the positive direction. Therefore, it is preferable that the trap level is closer to the vacuum level than the conduction band bottom level (Ec) of the oxide semiconductor film 108b. By adopting the above structure, electron accumulation in the trap level can be suppressed. As a result, the on-state current and field-effect mobility of the transistor can be increased.

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

[0251] By employing the above structure, the oxide semiconductor film 108b becomes the main path for current and is used as the channel region. Furthermore, since the oxide semiconductor films 108a and 108c include one or more of the metal elements contained in the oxide semiconductor film 108b that form the channel region, interface scattering is less likely to occur at the interface between oxide semiconductor films 108a and 108b or at the interface between oxide semiconductor films 108b and 108c. Therefore, since the movement of charge carriers at this interface is not hindered, the field-effect mobility of the transistor is improved.

[0252] To prevent oxide semiconductor films 108a and 108c from being used as part of the channel region, materials with sufficiently low conductivity are used for oxide semiconductor films 108a and 108c. Alternatively, oxide semiconductor films 108a and 108c are made of materials whose electron affinity (the difference between the vacuum level and the conduction band bottom level) is lower than that of oxide semiconductor film 108b and whose conduction band bottom level differs from that of oxide semiconductor film 108b (band shift). Furthermore, to suppress the difference between threshold voltages arising from drain voltage values, oxide semiconductor films 108a and 108c are preferably formed using materials whose conduction band bottom level is closer to the vacuum level than that of oxide semiconductor film 108b. For example, the difference between the conduction band bottom level of oxide semiconductor film 108b and the conduction band bottom level of oxide semiconductor films 108a and 108c is preferably 0.2 eV or more, more preferably 0.5 eV or more.

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

[0254] The thickness of the oxide semiconductor films 108a and 108c is greater than or equal to the thickness at which the diffusion of constituent elements of conductive films 112a and 112b into the oxide semiconductor film 108b is suppressed, and less than the thickness at which the supply of oxygen from the insulating film 114 to the oxide semiconductor film 108b is suppressed. For example, when the thickness of the oxide semiconductor films 108a and 108c is 10 nm or more, the diffusion of constituent elements of conductive films 112a and 112b into the oxide semiconductor film 108b can be suppressed. 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 oxide semiconductor films 108a and 108c are In-M-Zn oxides (M is Al, Ga, Y, or Sn), and the atomic ratio of M is higher than that of In, the band gap of oxide semiconductor films 108a and 108c can be increased while their electron affinity decreases. Therefore, the difference in electron affinity between oxide semiconductor films 108a and 108c and oxide semiconductor film 108b can be controlled according to the ratio of element M. Furthermore, because M is a metallic element with strong bonding with oxygen, oxygen defects are less likely to occur in oxide semiconductor layers where the atomic ratio of M is higher than that of In.

[0256] When In-M-Zn oxide is used as oxide semiconductor films 108a and 108c, the ratio of In to M (excluding Zn and O) is preferably: the atomic percentage of In is less than 50 atomic%, and the atomic percentage of M is greater than 50 atomic%, more preferably: the atomic percentage of In is less than 25 atomic%, and the atomic percentage of M is greater than 75 atomic%. Additionally, gallium oxide films can also be used as oxide semiconductor films 108a and 108c.

[0257] Furthermore, when the oxide semiconductor films 108a, 108b, and 108c are In-M-Zn oxides, the ratio of the number of M atoms in oxide semiconductor films 108a and 108c is greater than the ratio of the number of M atoms in oxide semiconductor film 108b. Typically, the ratio of the number of M atoms in oxide semiconductor films 108a and 108c is at least 1.5 times that of the ratio of M atoms in oxide semiconductor film 108b, preferably at least 2 times, and more preferably at least 3 times.

[0258] Furthermore, when the oxide semiconductor films 108a, 108b, and 108c are In-M-Zn oxides, and the atomic ratio of oxide semiconductor film 108b is In:M:Zn = x1:y1:z1, and the atomic ratio of oxide semiconductor films 108a and 108c is In:M:Zn = x2:y2:z2, then y2 / x2 is greater than y1 / x1. Preferably, y2 / x2 is at least 1.5 times y1 / x1, more preferably at least 2 times y1 / x1, and even more preferably at least 3 times or 4 times y1 / x1. In this case, y1 in oxide semiconductor film 108b is preferably at least x1, and the transistor including oxide semiconductor film 108b can have stable electrical characteristics. However, when y1 is at least 3 times x1, the field-effect mobility of the transistor including oxide semiconductor film 108b decreases. Therefore, y1 is preferably less than 3 times x1.

[0259] When the oxide semiconductor film 108b is an In-M-Zn oxide, and the atomic ratio of the metal elements in the target material used to form the oxide semiconductor film 108b is In:M:Zn = x1:y1:z1, x1 / y1 is preferably 1 / 3 or more and 6 or less, more preferably 1 or more and 6 or less, and z1 / y1 is preferably 1 / 3 or more and 6 or less, more preferably 1 or more and 6 or less. Note that when z1 / y1 is 1 or more and 6 or less, it is easy to form the oxide semiconductor film 108b as CAAC-OS (described later). Typical examples of the atomic ratio of the metal elements in the target material include In:M:Zn = 4:2:4.1, In:M:Zn = 1:1:1.2, and In:M:Zn = 3:1:2.

[0260] When the oxide semiconductor films 108a and 108c are In-M-Zn oxides, and the atomic ratio of the metal elements in the target material used to form the oxide semiconductor films 108a and 108c is In:M:Zn = x2:y2:z2, x2 / y2 < x1 / y1, and z2 / y2 is preferably 1 / 3 or more and 6 or less, more preferably 1 or more and 6 or less. When the atomic ratio of M is higher than that of In, the band gap of the oxide semiconductor films 108a and 108c can be widened and their electron affinity can be reduced, thereby y2 / x2 is preferably 3 or more or 4 or more. Typical examples of the atomic ratio of metal elements in a target material 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] Furthermore, when the oxide semiconductor films 108a and 108c are In-M oxides, if M does not contain divalent metal atoms (e.g., zinc), oxide semiconductor films 108a and 108c without a spinel-type crystal structure can be formed. For example, In-Ga oxide films can be used as oxide semiconductor films 108a and 108c. This In-Ga oxide film can be formed, for example, by sputtering using an In-Ga metal oxide target (In:Ga = 7:93). In order to form oxide semiconductor films 108a and 108c by sputtering using DC discharge, assuming the In:M atomic ratio is x:y, it is preferable that y / (x+y) is 0.96 or less, more preferably 0.95 or less, and for example, 0.93.

[0262] In oxide semiconductor films 108a, 108b, and 108c, the atomic ratio in the above atomic number ratio varies within a range of ±40% as an error.

[0263] exist FIG. 17B and FIG. 8A The oxide semiconductor film 108 of transistor Tr1 has a two-layer stacked structure or a three-layer stacked structure, and the oxide semiconductor film 128 of transistor Tr2 can also have the same structure.

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

[0265] <1-8. Manufacturing Method of Semiconductor Devices>

[0266] Next, refer to FIG. 9A and FIG. 10A and FIG. 11A A method for manufacturing a semiconductor device 100 according to one aspect of the present invention will be described.

[0267] also, FIG. 12A , FIG. 13A , FIG. 14A , FIG. 15A , FIG. 16A , FIG. 17A , FIG. 8B , FIG. 9B , FIG. 10B and FIG. 11B This is a top view illustrating the manufacturing method of the semiconductor device 100. FIG. 12B , FIG. 13B , FIG. 14B , FIG. 15B , FIG. 16B , FIG. 17B , FIG. 8A , FIG. 8B , FIG. 9A and FIG. 9B This is a cross-sectional view illustrating the manufacturing method of the semiconductor device 100.

[0268] First, a conductive film is formed on the substrate 102. This conductive film is then processed through photolithography and etching processes to form a conductive film 104, which serves as the first gate electrode. Next, an insulating film 106, which serves as the first gate insulating film, is formed on the conductive film 104 (see reference 104). FIG. 10A and FIG. 10B ).

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

[0270] Furthermore, the insulating film 106 may have a stacked structure of silicon nitride films. Specifically, the silicon nitride film may have a three-layer structure consisting of a first silicon nitride film, a second silicon nitride film, and a third silicon nitride film. An example of this three-layer structure is as follows.

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

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

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

[0274] Alternatively, 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 below.

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

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

[0277] Next, an oxide semiconductor film 108 is formed on the insulating film 106 (see reference). FIG. 11A and FIG. 11B ).

[0278] In this embodiment, an oxide semiconductor film is formed by sputtering using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). The substrate temperature during the formation of the oxide semiconductor film is 170°C. Oxygen gas with a flow rate of 60 sccm and argon gas with a flow rate of 140 sccm are used as the film-forming gases. The oxide semiconductor film is then processed into a desired shape, thereby forming an island-shaped oxide semiconductor film 108. Furthermore, a wet etching apparatus is used during the formation of the oxide semiconductor film.

[0279] Next, conductive films are formed on the insulating film 106 and the oxide semiconductor film 108, and processed into desired shapes, thereby forming conductive films 112a and 112b. Then, insulating films 114 and 116 (see reference) are formed on the insulating film 106, the oxide semiconductor film 108, and the conductive films 112a and 112b. FIG. 12A and FIG. 12B ).

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

[0281] After forming the conductive films 112a and 112b, the surface of the oxide semiconductor film 108 (on the back channel side) can also be washed. This washing can be performed, for example, using an etchant such as an aqueous solution of phosphoric acid. By washing, impurities (e.g., elements contained in the conductive films 112a and 112b) adhering to the surface of the oxide semiconductor film 108 can be removed. Note that this washing is not necessarily required and may be omitted depending on the circumstances.

[0282] During the formation of conductive films 112a and 112b and / or the washing process described above, the thickness of the region of oxide semiconductor film 108 not covered by conductive films 112a and 112b sometimes becomes thinner.

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

[0284] Preferably, after forming the insulating film 114, the insulating film 116 is continuously formed without exposure to the atmosphere. After forming the insulating film 114, the insulating film 116 is continuously formed by adjusting at least one of the source gas flow rate, pressure, high-frequency power, and substrate temperature without exposure to the atmosphere. This reduces the concentration of impurities originating from the atmosphere at the interface between the insulating films 114 and 116, and allows oxygen in the insulating films 114 and 116 to move into the oxide semiconductor film 108, thereby reducing the amount of oxygen defects in the oxide semiconductor film 108.

[0285] In this embodiment, as the insulating film 114, a silicon oxynitride film is formed using PECVD under the following conditions: the temperature of the substrate 102 is maintained at 220°C; silane with a flow rate of 50 sccm and nitrous oxide with a flow rate of 2000 sccm are used as the source gases; the pressure inside the processing chamber is 20 Pa; and a high-frequency power of 100 W (power density of 1.6 × 10⁻⁶) is applied at 13.56 MHz. -2 W / cm 2 It is supplied to the parallel plate electrodes.

[0286] As the insulating film 116, a silicon oxide film or a silicon oxynitride film is formed under the following conditions: the substrate temperature in the processing chamber of the PECVD apparatus, which has been vacuum-evacuated, is maintained at 180°C or higher and 350°C or lower; a source gas is introduced into the processing chamber; the pressure in the processing chamber is set to 100 Pa or higher and 250 Pa or lower, preferably 100 Pa or higher and 200 Pa or lower; and 0.17 W / cm² is supplied to the electrode disposed in the processing chamber. 2 Above and 0.5W / cm 2 The preferred value is 0.25 W / cm. 2 Above and 0.35W / cm 2 The following are high-frequency power values.

[0287] As the film-forming conditions for the insulating film 116, a high-frequency power with the aforementioned power density is supplied to the reaction chamber at the aforementioned pressure. This improves the decomposition efficiency of the source gas in the plasma, increases oxygen free radicals, and promotes the oxidation of the source gas. Therefore, the oxygen content in the insulating film 116 exceeds its stoichiometric composition. In the film formed at the substrate temperature within the aforementioned temperature range, the bonding force between silicon and oxygen is weak. Therefore, a portion of the oxygen in the film is released through subsequent heat treatment processes. Thus, an oxide insulating film with an oxygen content exceeding its stoichiometric composition and a portion of the oxygen released through heating can be formed.

[0288] Furthermore, in the process of forming the insulating film 116, the insulating film 114 is used as a protective film for the oxide semiconductor film 108. Therefore, the insulating film 116 can be formed using high-frequency power with high power density while minimizing damage to the oxide semiconductor film 108.

[0289] Furthermore, in the film formation conditions of the insulating film 116, increasing the flow rate of the silicon-containing deposition gas relative to the oxidizing gas can reduce the amount of defects in the insulating film 116. Typically, it is possible to form an oxide insulating film with a low amount of defects, wherein the spin density of the signal originating from silicon dangling bonds and appearing at g = 2.001, as measured by ESR, is less than 6 × 10⁻⁶. 17 spins / cm 3 Preferably 3×10 17 spins / cm 3 The following is more preferably 1.5 × 10 17 spins / cm 3 The result is that the reliability of transistor Tr1 can be improved.

[0290] Preferably, the heat treatment (hereinafter referred to as the first heat treatment) is performed after the insulating films 114 and 116 are formed. The first heat treatment can reduce the nitrogen oxides contained in the insulating films 114 and 116. The first heat treatment can also move a portion of the oxygen contained in the insulating films 114 and 116 to the oxide semiconductor film 108, thereby reducing the amount of oxygen defects in the oxide semiconductor film 108.

[0291] The temperature of the first heat treatment is typically below 400°C, preferably below 375°C, and more preferably above 150°C and below 350°C. The first heat treatment can be carried out in an atmosphere of nitrogen, oxygen, ultra-dry air (containing less than 20 ppm of water, preferably less than 1 ppm, and more preferably less than 10 ppb of water), or a rare gas (e.g., argon, helium). Furthermore, it is preferable that the nitrogen, oxygen, ultra-dry air, or rare gas does not contain hydrogen, water, or the like. An electric furnace, an RTA (rapid thermal anneal) apparatus, or the like can be used in this heat treatment.

[0292] Next, an oxide semiconductor film 128 is formed on the insulating film 116 (see reference). FIG. 13A and FIG. 13B ).

[0293] In this embodiment, an oxide semiconductor film is formed by sputtering using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). The substrate temperature during the formation of the oxide semiconductor film is 170°C. Oxygen gas with a flow rate of 60 sccm and argon gas with a flow rate of 140 sccm are used as the film-forming gases. The oxide semiconductor film is then processed into a desired shape, thereby forming an island-shaped oxide semiconductor film 128. Furthermore, a wet etching apparatus is used during the formation of the oxide semiconductor film.

[0294] Next, conductive films 122a, 122b, and 122c are formed on the insulating film 116 and the oxide semiconductor film 128. Then, insulating films 124 and 126 are formed on the insulating film 116, the oxide semiconductor film 128, and the conductive films 122a, 122b, and 122c (see reference). FIG. 14A and FIG. 14B ).

[0295] Conductive films 122a, 122b, and 122c can be formed using the same method as conductive films 112a and 112b described above. Insulating films 124 and 126 can be formed using the same method as insulating films 114 and 116 described above.

[0296] Next, openings 182 extending to the conductive film 122a are formed in the desired areas of the insulating films 124 and 126. Then, a conductive film 130 is formed on the insulating film 126 and the conductive film 122a (see reference). FIG. 15A and FIG. 15B ).

[0297] When forming the opening 182, either a dry etching apparatus or a wet etching apparatus can be used. An ITSO film with a thickness of 100 nm is formed using an oxide (also known as ITSO) target containing indium, tin and silicon (In2O3:SnO2:SiO2 = 85:10:5 [wt%]), which is then processed into an island shape to obtain a conductive film 130.

[0298] Next, a laminated film, which forms insulating films 134 and 136, is formed on insulating film 126 and conductive film 130. Then, an opening 184 reaching conductive film 130 is formed in a desired area of ​​the laminated film (see reference). FIG. 16A and FIG. 16B ).

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

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

[0301] Next, a conductive film is formed on the insulating film 136 and the conductive film 130, and it is processed into an island shape, thereby forming the conductive film 138 (see reference). FIG. 17A and FIG. 17B ).

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

[0303] Next, island-shaped insulating films 140 are formed on insulating film 136 and conductive film 138 (see reference). FIG. 1A and FIG. 1B ).

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

[0305] Next, an EL layer 142 is formed on the conductive film 138, and then a conductive film 144 is formed on the insulating film 140 and the EL layer 142, thereby obtaining the light-emitting element 160 (see reference). FIG. 18A and FIGS. 18B-29A ).

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

[0307] Through the above manufacturing processes, it is possible to manufacture FIG. 29B and FIG. 18A The semiconductor device 100 shown.

[0308] The structures and methods shown in this embodiment can be appropriately combined with the structures and methods shown in other embodiments.

[0309] Implementation Method 2

[0310] In this embodiment, refer to FIG. 18B and FIG. 18A and FIG. 18B A semiconductor device and a method for manufacturing a semiconductor device according to one aspect of the present invention will be described.

[0311] <2-1. Example 1 of the structure of a semiconductor device>

[0312] FIG. 18A This is a top view of a semiconductor device 200 according to one aspect of the present invention. FIG. 18B It is along FIG. 18AThe cross-sectional view of the dashed-dot line A1-A2 in the diagram. Furthermore, FIG. 18B 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).

[0313] FIG. 18A and FIG. 18B The semiconductor device 100 shown includes: a transistor Tr1; and a transistor Tr2, at least a portion of which overlaps with transistor Tr1. Furthermore, transistor Tr1 is a bottom-gate transistor, and transistor Tr2 is a top-gate transistor.

[0314] Since transistor Tr1 overlaps at least partially with transistor Tr2, the area of ​​the transistor can be reduced.

[0315] The transistor Tr1 includes: a conductive film 104 on a substrate 102; an insulating film 106 on the substrate 102 and the conductive film 104; an oxide semiconductor film 108 on the insulating film 106; a conductive film 112a on the oxide semiconductor film 108; a conductive film 112b on the oxide semiconductor film 108; an insulating film 114 on the oxide semiconductor film 108, the conductive film 112a and the conductive film 112b; an insulating film 116 on the insulating film 114; and an insulating film 118 on the insulating film 116, an insulating film 119 on the insulating film 118, an insulating film 210a on the insulating film 119, and a conductive film 212a on the insulating film 210a.

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

[0317] In addition, such as FIG. 18A and FIG. 18B As shown, oxide semiconductor film 108 and oxide semiconductor film 208 partially overlap each other.

[0318] The oxide semiconductor film 108 may have the same structure as that shown in Embodiment 1. The oxide semiconductor film 208 may have the same structure as that shown 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] FIG. 18A and FIG. 18B The semiconductor device 100 shown can be suitably used in the pixel circuit of a display device. FIG. 2 and ​ 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... ​ and ​ The layout shown can also increase the pixel aperture ratio.

[0322] In addition, in the ​ and ​ When the semiconductor device 100 shown is used in the pixel circuit of a display device, it can be used with, for example... ​ 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 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 212a as the second gate electrode. Furthermore, in transistor Tr1, insulating film 106 is used as the first gate insulating film, and insulating films 114, 116, 118, 119, and 210a are used as the second gate insulating films. In transistor Tr2, conductive film 112c is used as the first gate electrode, conductive film 218a as the source electrode, conductive film 218b as the drain electrode, and conductive film 212b as the second gate electrode. Furthermore, in transistor Tr2, insulating films 114, 116, 118, and 119 are used as the first gate insulating film, and insulating film 210b is used as the second gate insulating film.

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

[0327] An insulating film 136 is provided on the insulating film 216 and the conductive films 218a and 218b. An opening 186 is provided in the insulating film 136 to reach the conductive film 218b. Furthermore, a conductive film 138 is provided on the insulating film 136. In addition, the conductive film 138 is connected to the conductive film 218b in the opening 186.

[0328] In addition, an insulating film 140, an EL layer 142, and a conductive film 144 are disposed on the conductive film 138. The light-emitting element 160 is constituted by the conductive film 138, the EL layer 142, and the conductive film 144.

[0329] As described above, one aspect of the present invention can combine bottom-gate transistors and top-gate transistors.

[0330] Furthermore, although not illustrated, FIG. 18A and FIG. 18B The transistors Tr1 and Tr2 shown can also have the S-channel structure described in Embodiment 1.

[0331] The transistors Tr1 and Tr2 included in the semiconductor device 200 of this embodiment can be combined with the transistors Tr1 and Tr2 included in the semiconductor device 100 of Embodiment 1.

[0332] 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.

[0333] <2-2. Components of a Semiconductor Device>

[0334] Next, the constituent elements of the semiconductor device of this embodiment will be 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 (conductive film 104, conductive film 112a, conductive film 112b, conductive film 122a, conductive film 122b, conductive film 122c, conductive film 130, conductive film 138, and conductive film 144) shown in Embodiment 1. In particular, oxide conductors (OC) are preferably used as conductive films 212a and 212b 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 material of the insulating films (insulating film 106, insulating film 114, insulating film 116, insulating film 124, insulating film 126, insulating film 134, insulating film 136, and insulating film 140) shown in Embodiment 1.

[0339] In particular, a silicon nitride film or a silicon oxynitride film is preferably used as the insulating film 118, which can suppress the incorporation of impurities 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, and more preferably a silicon oxide film or a silicon oxynitride film is used as the insulating film 119. Oxide insulating films are preferably used as insulating films 210a and 210b. The insulating films 210a and 210b preferably have regions where the oxygen content exceeds the stoichiometric composition (excess oxygen regions). Silicon oxide films or silicon oxynitride films are preferably used as insulating films 210a and 210b.

[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 functions to block oxygen, hydrogen, water, alkali metals, alkaline earth metals, etc. Since the oxide semiconductor film 208 is in contact with the insulating film 214, one or both of the hydrogen and nitrogen in the insulating film 214 enter the oxide semiconductor film 208, thereby increasing the carrier density of the oxide semiconductor film 208. Therefore, the region in the oxide semiconductor film 208 that is in contact with the insulating film 214 is used as a source region or a drain region.

[0341] [Oxide semiconductor film]

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

[0343] <2-3. Manufacturing Method of Semiconductor Devices>

[0344] Next, refer to FIG. 19A and FIG. 19B to FIG. 29A and FIG. 29B A method for manufacturing a semiconductor device 200 according to one aspect of the present invention will be described.

[0345] also, FIG. 19A , FIG. 20A , FIG. 21A , FIG. 22A , FIG. 23A , FIG. 24A , FIG. 25A , FIG. 26A , FIG. 27A , FIG. 28A and FIG. 29A This is a top view illustrating the manufacturing method of 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 This is a cross-sectional view illustrating the manufacturing method of the semiconductor device 200.

[0346] First, a conductive film is formed on the substrate 102. This conductive film is then processed through photolithography and etching processes to form a conductive film 104, which serves as the first gate electrode. Next, an insulating film 106, which serves as the first gate insulating film, is formed on the conductive film 104 (see reference 104). FIG. 19A and FIG. 19B ).

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

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

[0349] In this embodiment, an oxide semiconductor film is formed by sputtering using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). The substrate temperature during the formation of the oxide semiconductor film is 170°C. Oxygen gas with a flow rate of 60 sccm and argon gas with a flow rate of 140 sccm are used as the film-forming gases. The oxide semiconductor film is then processed into a desired shape, thereby forming an island-shaped oxide semiconductor film 108. Furthermore, a wet etching apparatus is used during the formation of the oxide semiconductor film.

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

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

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

[0353] Preferably, the first heat treatment is performed after the insulating films 114, 116, 118, and 119 are formed. This first heat treatment allows a portion of the oxygen contained in the insulating films 114 and 116 to move to the oxide semiconductor film 108, thereby reducing the amount of oxygen defects in the oxide semiconductor film 108.

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

[0355] In this embodiment, an oxide semiconductor film is formed by sputtering using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). The substrate temperature during the formation of the oxide semiconductor film is 170°C. Oxygen gas with a flow rate of 60 sccm and argon gas with a flow rate of 140 sccm are used as the film-forming gases. The oxide semiconductor film is then processed into a desired shape, thereby forming an island-shaped oxide semiconductor film 208. Furthermore, a wet etching apparatus is used during the formation of the oxide semiconductor film.

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

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

[0358] A portion of the oxide semiconductor film 208 and the conductive films 212a and 212b are in contact with the insulating film 214 and one or both of hydrogen and nitrogen from the insulating film 214 are added, thereby becoming an oxide conductor (OC).

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

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

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

[0362] Next, conductive films are formed on the insulating film 216 and the oxide semiconductor film 208 by filling the openings 282a and 282b, and these are processed into island shapes, thereby forming conductive films 218a and 218b (see reference). FIG. 25A and FIG. 25B ).

[0363] As 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 sputtering.

[0364] Next, an insulating film 136 is formed on the insulating film 216 and the conductive films 218a and 218b. Then, the desired area of ​​the insulating film 136 is processed to form an opening 186 reaching the conductive film 218b (see reference). FIG. 26A and FIG. 26B ).

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

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

[0367] As the conductive film 138 in this embodiment, a laminated film consisting of an ITSO film with a thickness of 10 nm, a reflective metal film with a thickness of 200 nm (here, a metal film containing silver, palladium, and copper is used), and an ITSO 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, island-shaped insulating films 140 are formed on insulating film 136 and conductive film 138 (see reference). 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, an EL layer 142 is formed on the conductive film 138, and then a conductive film 144 is formed on the insulating film 140 and the EL layer 142, thereby obtaining the light-emitting element 160 (see reference). FIG. 29A and FIG. 29B ).

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

[0372] Through the above manufacturing processes, it is possible to manufacture FIG. 18A and FIG. 18B The semiconductor device 200 shown.

[0373] The structures and methods shown in this embodiment can be appropriately combined with the structures and methods shown in other embodiments.

[0374] Implementation Method 3

[0375] In this embodiment, refer to FIG. 30A and FIG. 30B to FIG. 45A and FIG. 45B A semiconductor device and a method for manufacturing a semiconductor device according to one aspect of the present invention will be described.

[0376] <3-1. Example 1 of the structure of a semiconductor device>

[0377] FIG. 30A This is a top view of a semiconductor device 300 according to one embodiment of the present invention. FIG. 30B It is along FIG. 30A The cross-sectional view of the dashed-dot line A1-A2 in the diagram. Furthermore, FIG. 30B 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).

[0378] In addition, FIG. 30A For convenience, some components of the semiconductor device 300 (e.g., the insulating film used as a gate insulating film) and some of the symbols for the components are not shown. Note that in the subsequent top view of the semiconductor device, some are also shown. FIG. 30A Similarly, neither part of the constituent elements nor part of the symbols of the constituent elements are shown.

[0379] FIG. 30A and FIG. 30B The semiconductor device 300 shown includes transistor Tr1 and transistor Tr2. Transistor Tr1 is at least partially overlapped with transistor Tr2. Furthermore, transistor Tr1 is a top-gate transistor and transistor Tr2 is a bottom-gate transistor.

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

[0381] 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. 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.

[0382] Furthermore, the transistor Tr1 includes: an insulating film 316 on the insulating film 314; a conductive film 312a electrically connected to a source region 308s in 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 a drain region 308d in 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 on the insulating film 316, the conductive film 312a, and the conductive film 312b.

[0383] Transistor Tr2 includes: a conductive film 312b; an insulating film 318 on the conductive film 312b; an oxide semiconductor film 328 on the insulating film 318; a conductive film 322a on the oxide semiconductor film 328; a conductive film 322b on the oxide semiconductor film 328; an insulating film 324 on the oxide semiconductor film 328, the conductive film 322a, and the conductive film 322b; an insulating film 326 on the insulating film 324; and a conductive film 330 on the insulating film 326. Furthermore, the conductive film 330 is connected to the conductive film 322a through an opening 382 provided in the insulating films 324 and 326.

[0384] like FIG. 30A and FIG. 30B As shown, oxide semiconductor film 308 and oxide semiconductor film 328 partially overlap each other. Additionally, as... FIG. 30A and FIG. 30B As shown, preferably, the channel region formed in the oxide semiconductor film 308 of transistor Tr1 does not overlap with the channel region formed in the oxide semiconductor film 328 of transistor Tr2.

[0385] If the channel regions of transistor Tr1 and transistor Tr2 overlap, one transistor may sometimes affect the other during operation. To avoid this negative impact, structures that increase the spacing between transistors Tr1 and Tr2, or structures that provide a conductive film between transistors Tr1 and Tr2, can be used. However, using the former structure increases the thickness of the semiconductor device. Therefore, problems such as bendability may occur, for example, when forming the semiconductor device 300 on a flexible substrate. Using the latter structure involves the need for a conductive film formation process and an increase in the thickness of the semiconductor device.

[0386] On the other hand, in one embodiment of the semiconductor device 300 of the present invention, transistors Tr1 and Tr2 overlap, and the channel regions of each transistor do not overlap. Furthermore, since portions of the oxide semiconductor films forming the channel regions overlap, the area of ​​the transistors can be appropriately reduced.

[0387] Furthermore, both oxide semiconductor films 308 and 328 contain In, M (where M is Al, Ga, Y, or Sn), and Zn. For example, oxide semiconductor films 308 and 328 preferably have regions where the atomic ratio of In is greater than the atomic ratio of M. Note that the semiconductor devices of one aspect of the present invention are not limited thereto; they may have regions where the atomic ratio of In is less than the atomic ratio of M, or they may have regions where the atomic ratio of In is equal to the atomic ratio of M.

[0388] Preferably, the composition of the oxide semiconductor film 308 is the same as or substantially the same as the composition 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, manufacturing costs can be reduced. Note that the semiconductor device of one embodiment of the present invention is not limited thereto, and the compositions of the oxide semiconductor film 308 and the oxide semiconductor film 328 may also be different from each other.

[0389] When both oxide semiconductor films 308 and 328 have regions where the ratio of In atoms is greater than the ratio of M atoms, the field-effect mobility of transistors Tr1 and Tr2 can be improved. 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.

[0390] 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.

[0391] FIG. 30A and FIG. 30B The semiconductor device 300 shown can be suitably used in the pixel circuit of a display device. FIG. 30A and FIG. 30B 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... FIG. 31 and FIG. 30AThe layout shown can also increase the pixel aperture ratio. Note that ppi is a unit that represents the number of pixels per inch.

[0392] <3-2. Pixel Circuit of Display Device>

[0393] Reference FIG. 30B To the general FIG. 31 and FIG. 31 An example of the semiconductor device 300 being used in the pixel circuit of a display device will be described.

[0394] FIG. 31 This is a circuit diagram illustrating an example of using a semiconductor device 300 in a pixel circuit of a display device.

[0395] FIG. 30A The semiconductor device 300 shown includes: transistor Tr1; transistor Tr2; capacitor Cs1; and light-emitting element 360. Note that... FIG. 30B An example is shown where two semiconductor devices 300 are adjacent in the column direction. The semiconductor devices 300 are used as pixels (also referred to as sub-pixels). Although FIG. 31 and FIG. 30A The capacitor Cs1 is not shown in the figure, but it can be formed by the parasitic capacitance between the conductive film 312b included in transistor Tr1 and the conductive film 322b included in transistor Tr2.

[0396] FIG. 30B The 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.

[0397] 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.

[0398] 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.

[0399] One of the source and drain electrodes of 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 example shown is of a semiconductor device 300 used for displaying pixels.

[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-dash 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, conductive film 312b and conductive film 330 have regions located outside the side end of oxide semiconductor film 328.

[0417] By employing the above structure, the electric fields of conductive films 312b and 330 can be used to surround the oxide semiconductor film 328 included in transistor Tr2. A device structure in which the electric fields of the first and second gate electrodes, such as transistor Tr2, surround the oxide semiconductor film forming the channel region is called a surrounded channel (S-channel) structure.

[0418] Because transistor Tr2 has an S-channel structure, an electric field for inducing a channel can be effectively applied to the oxide semiconductor film 328 using the conductive film 312b, which serves as the first gate electrode. This improves the current-driving capability of transistor Tr2, resulting in high on-state current characteristics. Furthermore, since the on-state current can be increased, the size of transistor Tr2 can be reduced. Additionally, because transistor Tr2 has a structure in which the conductive film 312b, used as the first gate electrode, and the conductive film 330, used as the second gate electrode, surround the oxide semiconductor film 328, the mechanical strength of transistor Tr2 can be improved.

[0419] Although FIG. 30A In the transistor Tr2 shown, the conductive film 330, which serves as the second gate electrode, is electrically connected to the conductive film 322a, which serves as the source or drain electrode of the transistor Tr2. However, one aspect of the invention is not limited to this. For example, the first gate electrode can also be connected to the second gate electrode. In this case, openings are formed in the insulating films 318, 324, and 326, allowing the conductive film 330, which serves as the second gate electrode, to be electrically connected to the conductive film 312b, which serves as the first gate electrode, through these openings. Therefore, the conductive films 312b and 330 are supplied with the same potential.

[0420] <3-5. Components of a Semiconductor Device>

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

[0422] [Substrate]

[0423] There are no particular restrictions on the material of substrate 302, as long as it is a heat-resistant material capable of withstanding subsequent heat treatment. For example, glass substrates, ceramic substrates, quartz substrates, and sapphire substrates can be used as substrate 302. Substrate 302 can also be a single-crystal semiconductor substrate or a polycrystalline semiconductor substrate made of silicon or silicon carbide, a compound semiconductor substrate made of silicon-germanium, or an SOI (silicon-on-insulator) substrate. Substrates on which semiconductor elements are disposed can also be used as substrate 302. When a glass substrate is used as substrate 302, large display devices can be manufactured using glass substrates of the following sizes: 6th generation (1500mm × 1850mm), 7th generation (1870mm × 2200mm), 8th generation (2200mm × 2400mm), 9th generation (2400mm × 2800mm), and 10th generation (2950mm × 3400mm).

[0424] A flexible substrate can also be used as substrate 302, and the semiconductor device 300 can be directly disposed on the flexible substrate. Alternatively, a release layer can be disposed between substrate 302 and semiconductor device 300. The release layer can be used when a portion or all of the semiconductor device formed on the release layer is separated from substrate 302 and transferred to another substrate. In this case, semiconductor device 300 can be transferred to a substrate with low heat resistance or a flexible substrate.

[0425] <Conductive film>

[0426] Conductive films 312a, 312b, 320, 322a, 322b, 330, 338 and 344 may be formed using metallic elements 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) and cobalt (Co), alloys containing the above metallic elements as components, or alloys containing combinations of the above metallic elements.

[0427] Conductive films 312a, 312b, 320, 322a, 322b, 330, 338, and 344 may be formed using oxide conductors such as oxides containing indium and tin, oxides containing tungsten and indium, oxides containing tungsten, indium, and zinc, oxides containing titanium and indium, oxides containing titanium, indium, and tin, oxides containing indium and zinc, oxides containing silicon, indium, and tin, and oxides containing indium, gallium, and zinc.

[0428] In particular, the aforementioned oxide conductor is applicable to conductive films 320 and 330. Here, the oxide conductor will be described. In this specification, the oxide conductor may also be referred to as an OC (oxide conductor). For example, an oxide conductor is obtained by forming oxygen vacancies in an oxide semiconductor and then adding hydrogen to these oxygen vacancies to form donor levels near the conduction band. As a result, the conductivity of the oxide semiconductor increases, thus becoming a conductor. Oxide semiconductors that can become conductors are called oxide conductors. Generally, because oxide semiconductors have a large band gap, visible light is transmitted through them. An oxide conductor is an oxide semiconductor with donor levels near the conduction band. Therefore, the effect of absorption due to donor levels is small in an oxide conductor, and thus, the oxide conductor has visible light transmittance equivalent to that of an oxide semiconductor.

[0429] As conductive films 312a, 312b, 322a, 322b, 330, 338, and 344, Cu-X alloy films (where X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti) can be used. By using Cu-X alloy films, manufacturing costs can be reduced because the films can be processed through a wet etching process.

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

[0431] The materials used as one or more of the conductive films 312a, 312b, 320, 322a, 322b and 330 are particularly preferably one or more of the aforementioned metallic elements, namely aluminum, copper, titanium, tungsten, tantalum and molybdenum.

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

[0433] [Insulating film]

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

[0435] The insulating film 306 is used as a barrier film to inhibit oxygen permeation. For example, when one or more of the insulating films 314, 316, 308, 328, 324, and 326 have excess oxygen regions, the insulating film 306 can inhibit oxygen permeation.

[0436] Furthermore, the insulating film in contact with one or both of the oxide semiconductor films 308 and 328 is preferably an oxide insulating film, and preferably has a region where the oxygen content exceeds the stoichiometric composition (excess oxygen region). In other words, the oxide insulating film with the excess oxygen region is capable of releasing oxygen.

[0437] For example, excess oxygen regions in an oxide insulating film can be formed by: forming the insulating film in an oxygen atmosphere; heating the insulating film in an oxygen atmosphere after its formation; or adding oxygen to the insulating film after its formation. Plasma treatment is preferred as a method for adding oxygen to the insulating film after film formation.

[0438] The insulating film used as the gate insulating film for transistors Tr1 and Tr2 can be formed using hafnium oxide. When hafnium oxide is used as the insulating film for the gate insulating film, the following effects are achieved.

[0439] Hafnium oxide has a higher relative permittivity than silicon oxide and silicon oxynitride. Therefore, the insulating film formed using hafnium oxide can be thicker than that formed using silicon oxide, thereby reducing leakage current caused by tunneling current. In other words, transistors with low off-state current can be manufactured. Furthermore, hafnium oxide with a crystalline structure has a higher relative permittivity than hafnium oxide with an amorphous structure. Therefore, hafnium oxide with a crystalline structure is preferred for manufacturing transistors with low off-state current. Examples of crystalline structures include monoclinic and cubic crystal systems. Note that one aspect of the invention is not limited to the above examples.

[0440] The insulating film used as the gate insulating film for transistors Tr1 and Tr2 can be formed using silicon nitride. When silicon nitride is used as the insulating film for the gate, the following effects are achieved: Compared to silicon oxide, silicon nitride has a higher relative permittivity and requires a larger thickness to obtain the same capacitance as silicon oxide. Therefore, the thickness of the gate insulating film can be increased. Consequently, electrostatic discharge (ESD) damage to transistors Tr1 and Tr2 can be prevented by suppressing the drop in dielectric breakdown voltage and increasing the dielectric breakdown voltage.

[0441] Insulating films 310, 316, 318, 324, and 326 function to supply oxygen to oxide semiconductor films 308 and / or 328. That is, insulating films 310, 316, 318, 324, and 326 contain oxygen. Insulating films 310 and 324 are insulating films that allow oxygen to permeate. Note that insulating film 310 is also used as a film to mitigate damage to oxide semiconductor film 308 during the subsequent process of forming conductive film 320. Insulating film 324 is also used as a film to mitigate damage to oxide semiconductor film 328 during the subsequent process of forming insulating film 326.

[0442] As insulating films 310 and 324, silicon oxide films, silicon oxynitride films, etc., with a thickness of 5 nm or more and 150 nm or less can be used, preferably 5 nm or more and 50 nm or less.

[0443] Furthermore, it is preferable to have a low amount of defects in the insulating films 310 and 324. Typically, the spin density of the signal originating from silicon dangling bonds and appearing at g = 2.001, as measured by electron spin resonance (ESR), is preferably 3 × 10⁻⁶. 17 spins / cm 3 The reason is that if the defect density of insulating films 314 and 324 is high, oxygen will bond with the defect, thus reducing the amount of oxygen permeating into insulating film 314.

[0444] Insulating films 310 and 324 can be formed using oxide insulating films due to the low density of states of nitrides. Note that this density of states due to nitrides can sometimes be formed at the energy (E) at the valence band top of the oxide semiconductor film. V_OS ) and the energy at the bottom of the conduction band (E) C_OS Between ), and as the above-mentioned oxide insulating film, silicon oxynitride film with low nitrogen oxide emission, aluminum oxynitride film with low nitrogen oxide emission, etc., can be used.

[0445] Furthermore, in thermal desorption spectroscopy (TDS), silicon oxynitride films with low nitrogen oxide release are those with higher ammonia release than nitrogen oxide release, typically with an ammonia release of 1 × 10⁻⁶.18 cm -3 Above and 5×10 19 cm -3 The following is a note: The ammonia release figures above refer to the total amount of ammonia released during heat treatment in TDS at temperatures ranging from 50°C to 650°C or from 50°C to 550°C. The ammonia release figures above are the total amount of ammonia released in TDS, converted to ammonia molecules.

[0446] Nitrogen oxides (NO) x (where x is greater than 0 and less than 2, preferably greater than 1 and less than 2), typically NO2 or NO forms an energy level in the insulating films 310 and 324. This energy level is located in the band gap of the oxide semiconductor films 308 and 328. Therefore, when nitrogen oxides diffuse 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, electrons are sometimes trapped at this energy level on the insulating film 310 or 324 side. As a result, the trapped electrons remain near the interface between the insulating film 310 and the oxide semiconductor film 308, or near the interface between the insulating film 324 and the oxide semiconductor film 328, thereby causing the threshold voltage of the transistor to drift in the positive direction.

[0447] During the heat treatment, nitrogen oxides react with ammonia and oxygen. Because the nitrogen oxides contained in insulating film 324 react with the ammonia contained in insulating film 326 during the heat treatment, the amount of nitrogen oxides contained in insulating film 324 is reduced. Therefore, electrons are less likely to be trapped at the interface between insulating film 324 and oxide semiconductor film 328.

[0448] By using the aforementioned oxide insulating film, insulating films 310 and 324 can reduce the drift of the threshold voltage of the transistor, thereby reducing the variation in the electrical characteristics of the transistor.

[0449] Through heat treatment during transistor manufacturing, typically above 300°C and below 350°C, ESR spectra of insulating films 310 and 324 below 100K were observed. These spectra included 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 separation 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 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 (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.

[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] Insulating films 316, 318, and 326 are formed using oxide insulating films with an oxygen content exceeding the stoichiometric composition. Upon heating, a portion of the oxygen is released from the oxide insulating film with the oxygen content exceeding the stoichiometric composition. The amount of oxygen released from the oxide insulating film with the oxygen content exceeding the stoichiometric composition is 1.0 × 10⁻⁶ oxygen molecules converted to TDS. 19 cm -3 The preferred value is 3.0 × 10⁴. 20 cm -3 That's all. Note that the oxygen release figures above refer to the total amount of oxygen released during heat treatment in TDS at temperatures ranging from 50°C to 650°C or from 50°C to 550°C. The oxygen release figures above are the total amount of oxygen released in TDS, converted to oxygen molecules.

[0455] The insulating films 316, 318, and 326 can be silicon oxide films, silicon oxynitride films, etc., with a thickness of 30 nm or more and 500 nm or less, preferably 50 nm or more and 400 nm or less.

[0456] Furthermore, it is preferable to have a low amount of defects in the insulating films 316, 318, and 326. Typically, the spin density of the signal originating from silicon dangling bonds and appearing at g = 2.001, as measured by ESR, is less than 1.5 × 10⁻⁶. 18 spins / cm 3 More preferably 1×10 18 spins / cm 3 the following.

[0457] Since insulating films 324 and 326 can be formed using insulating films containing the same type of material, the interface between insulating films 324 and 326 is sometimes not clearly identifiable. Therefore, in this embodiment, the interface between insulating films 324 and 326 is indicated by a dashed line.

[0458] Insulating film 334 is used as a protective insulating film for transistors Tr1 and Tr2.

[0459] The insulating film 334 contains one or both of hydrogen and nitrogen. Additionally, the insulating film 334 contains nitrogen and silicon. The insulating film 334 functions to block oxygen, hydrogen, water, alkali metals, alkaline earth metals, etc. By providing the insulating film 334, it is possible to prevent oxygen from diffusing from the oxide semiconductor film 308 and oxide semiconductor film 328 to the outside, and it is also possible to prevent the oxygen contained in the insulating films 310, 316, 324, and 326 from diffusing to the outside. Furthermore, it is possible to prevent hydrogen, water, etc., from intruding into the oxide semiconductor films 308 and 328 from the outside.

[0460] The insulating film 334 can be formed, for example, using a nitride insulating film. This nitride insulating film is formed using silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, etc.

[0461] [Oxide semiconductor film]

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

[0463] When both oxide semiconductor films 308 and 328 contain In-M-Zn oxide, the atomic ratio of the metal elements in the sputtering target used to form the In-M-Zn oxide preferably satisfies In > M. For example, the atomic ratio of the metal elements in such a sputtering target is In:M:Zn = 2:1:3, In:M:Zn = 3:1:2, or In:M:Zn = 4:2:4.1.

[0464] When both oxide semiconductor film 308 and oxide semiconductor film 328 contain In-M-Zn oxide, the atomic ratio of the metal elements in the sputtering target used to form the In-M-Zn oxide preferably satisfies In≤M. For example, the atomic ratio of the metal elements in such sputtering target is 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, In∶M∶Zn=1∶3∶6.

[0465] When both oxide semiconductor films 308 and 328 are In-M-Zn oxides, a sputtering target containing polycrystalline In-M-Zn oxide is preferably used. By using a target containing polycrystalline In-M-Zn oxide, crystalline oxide semiconductor films 308 and 328 can be easily formed. Note that the atomic ratio of metal elements in the formed oxide semiconductor films 308 and 328 varies within ±40% of the atomic ratio of metal elements in the aforementioned sputtering target. For example, when a sputtering target with an In:Ga:Zn atomic ratio of 4:2:4.1 is used as the sputtering target for oxide semiconductor films 308 and 328, the In:Ga:Zn atomic ratio of oxide semiconductor films 308 and 328 is sometimes 4:2:3 or close to 4:2:3.

[0466] The band gaps of the oxide semiconductor films 308 and 328 are 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. By using such oxide semiconductors with wider band gaps, the off-state currents of transistors Tr1 and Tr2 can be reduced.

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

[0468] Hydrogen contained in oxide semiconductor films 308 and 328 reacts with oxygen bonded to metal atoms to form water, while oxygen defects are formed in the lattice (or the portion where oxygen desorption occurs) where oxygen desorption takes place. When hydrogen enters this oxygen defect, electrons are sometimes generated as charge carriers. Additionally, sometimes a portion of the hydrogen bonds with oxygen bonded to metal atoms, generating electrons as charge carriers. Therefore, transistors containing oxide semiconductor films containing hydrogen tend to have always-on characteristics. Thus, it is preferable to minimize the amount of hydrogen in oxide semiconductor films 308 and 328.

[0469] Specifically, in oxide semiconductor films 308 and 328, the hydrogen concentration measured using SIMS was 2 × 10⁻⁶. 20 atoms / cm 3 The following is preferred: 5×10 19 atoms / cm 3 Hereinafter, 1×10 is more preferred. 19 atoms / cm 3 The following is more preferably 5×10 18 atoms / cm 3 Hereinafter, 1×10 is more preferred. 18 atoms / cm 3 The following is more preferably 5×10 17 atoms / cm 3 Hereinafter, 1×10 is further preferred. 16 atoms / cm 3 the following.

[0470] When oxide semiconductor films 308 and 328 contain silicon or carbon, one of Group 14 elements, oxygen vacancies increase in oxide semiconductor films 308 and 328, making oxide semiconductor films 308 and 328 n-type films. Therefore, the silicon concentration in oxide semiconductor films 308 and 328, as measured by SIMS analysis, is 2 × 10⁻⁶. 18 atoms / cm 3 The following is preferred: 2×10 17 atoms / cm 3 The carbon concentration in oxide semiconductor films 308 and 328, as determined by SIMS analysis, is 2 × 10⁻⁶. 18 atoms / cm 3 The following is preferred: 2×10 17 atoms / cm 3 the following.

[0471] Furthermore, the concentrations of alkali metals or alkaline earth metals in oxide semiconductor films 308 and 328, as determined by SIMS analysis, were 1 × 10⁻⁶. 18 atoms / cm 3The following is preferred: 2×10 16 atoms / cm 3 The following applies. When alkali metals and alkaline earth metals bond with oxide semiconductors, charge carriers are sometimes generated, which increases the off-state current of the transistor. Therefore, it is preferable to reduce the concentration of alkali metals or alkaline earth metals in oxide semiconductor films 308 and 328.

[0472] The oxide semiconductor films 308 and 328 may, for example, have non-single-crystal structures. Examples of non-single-crystal structures include CAAC-OS (c-axis-aligned crystalline oxide semiconductor), polycrystalline structures, microcrystalline structures, and amorphous structures. Among non-single-crystal structures, amorphous structures have the highest defect state density, while CAAC-OS has the lowest defect state density.

[0473] The various films described above, such as conductive films, insulating films, and oxide semiconductor films, can be formed using sputtering, plasma-enhanced chemical vapor deposition (PECVD), and thermal CVD. Examples of thermal CVD include MOCVD (metal-organic chemical vapor deposition) and ALD (atomic layer deposition).

[0474] Thermal CVD is a film formation method that does not use plasma, thus having the advantage of not producing defects caused by plasma damage.

[0475] Film formation using thermal CVD can be performed by simultaneously supplying source gas and oxidant into the processing chamber, setting the pressure inside the processing chamber to atmospheric pressure or depressurization, so that the reaction occurs near or on the substrate.

[0476] Alternatively, film formation using the ALD method can be performed under the following conditions: the pressure inside the processing chamber is set to atmospheric pressure or reduced pressure, and a source gas is used for the reaction.

[0477] Various films, such as conductive films, insulating films, and oxide semiconductor films, as described in this embodiment can be formed using thermal CVD methods such as MOCVD or ALD. For example, the In-Ga-Zn-O film can be formed using trimethylindium, trimethylgallium, and dimethylzinc. The chemical formula of trimethylindium is In(CH3)3. The chemical formula of trimethylgallium is Ga(CH3)3. Additionally, the chemical formula of dimethylzinc is Zn(CH3)2. Not limited to the above combinations, triethylgallium (chemical formula: Ga(C2H5)3) can be used instead of trimethylgallium, and diethylzinc (chemical formula: Zn(C2H5)2) can be used instead of dimethylzinc.

[0478] For example, when forming a hafnium oxide film using an ALD (Alternating Discharge) method film-forming apparatus, two gases are used: ozone (O3) as an oxidant; and a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide, tetradimethylammonium hafnium (TDMAH), etc.). Furthermore, the chemical formula of tetradimethylammonium hafnium is Hf[N(CH3)2]4. As an example of other liquid materials, tetra(ethylmethylammonium)hafnium is also used.

[0479] For example, when forming an alumina film using an ALD (Alternating Dissolved Carbon) method film-forming apparatus, two gases are used: H₂O as an oxidant; and a source gas obtained by vaporizing a liquid containing a solvent and an aluminum precursor compound (e.g., trimethylaluminum (TMA)). Furthermore, the chemical formula of trimethylaluminum is Al(CH₃)₃. Examples of other liquid materials include tris(dimethylamide)aluminum, triisobutylaluminum, and aluminum tris(2,2,6,6-tetramethyl-3,5-heptadecane).

[0480] For example, when forming a silicon oxide film using an ALD film-forming apparatus, hexachlorosilane is attached to the film-forming surface to remove chlorine contained in the attachment, and free radicals of an oxidizing gas (e.g., O2, nitrous oxide) are supplied to react with the attachment.

[0481] For example, when forming a tungsten film using an ALD (Alternating Discharge) method film deposition apparatus, an initial tungsten film is formed using WF6 gas and B2H6 gas, and then the final tungsten film is formed using WF6 gas and H2 gas. Note that SiH4 gas can also be used instead of B2H6 gas.

[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. Structural Example 2 of a Semiconductor Device>

[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 It is a cross-sectional view of the transistor Tr2 included in the semiconductor device 300 along the channel length (L) direction.

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

[0492] FIG. 35B The diagram illustrates the structure of the oxide semiconductor film 328 of transistor Tr2, comprising an oxide semiconductor film 328b and an oxide semiconductor film 328c on top of 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 the 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 an energy band diagram along the film thickness direction of a stacked body is shown, the stacked body having an insulating film 318, oxide semiconductor films 328a, 328b, 328c and an insulating film 324. FIG. 35B An example of an energy band diagram along the film thickness direction is shown, the stack having an insulating film 318, oxide semiconductor films 328b, 328c, and an insulating film 324. For ease of understanding, the energy levels (Ec) of the conduction band bottoms of the insulating films 318, 328b, 328c, and 324 are shown in the energy band diagram.

[0495] FIG. 35A The energy band diagram is as follows: Silicon oxide films are used as insulating films 318 and 324; oxide semiconductor film 328a is an oxide semiconductor film formed by using a metal oxide target with an atomic ratio of In:Ga:Zn = 1:3:2; oxide semiconductor film 328b is an oxide semiconductor film formed by using a metal oxide target with an atomic ratio of In:Ga:Zn = 4:2:4.1; and oxide semiconductor film 328c is an oxide semiconductor film formed by using a metal oxide target with an atomic ratio of In:Ga:Zn = 1:3:2.

[0496] FIG. 35BThe energy band diagram is as follows: Silicon oxide films are used as insulating films 318 and 324; oxide semiconductor film 328b is an oxide semiconductor film formed by using a metal oxide target with an atomic ratio of In:Ga:Zn = 4:2:4.1; and oxide semiconductor film 328c is a metal oxide film formed by using a metal oxide target with an atomic ratio of In:Ga:Zn = 1:3:2.

[0497] like FIG. 35A and FIG. 35B As shown, the energy levels at the bottom of the conduction band change smoothly between oxide semiconductor films 328a and 328b, and between oxide semiconductor films 328b and 328c. In other words, the energy levels at the bottom of the conduction band change continuously or are continuously joined. To achieve such a band structure, impurities that could form defect energy levels such as trap centers or recombination centers must not exist at the interfaces between oxide semiconductor films 328a and 328b, or between oxide semiconductor films 328b and 328c.

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

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

[0500] By setting oxide semiconductor film 328a and / or oxide semiconductor film 328c, oxide semiconductor film 328b can be moved away from the trap energy level.

[0501] Furthermore, sometimes the trap level is farther from the vacuum level than the conduction band bottom level (Ec) of the oxide semiconductor film 328b used as the channel region, and electrons tend to accumulate in the trap level. When electrons accumulate in the trap level, they become negative fixed charges, causing the threshold voltage of the transistor to drift in the positive direction. Therefore, it is preferable that the trap level is closer to the vacuum level than the conduction band bottom level (Ec) of the oxide semiconductor film 328b. By adopting the above structure, electron accumulation in the trap level can be suppressed. As a result, the on-state current and field-effect mobility of the transistor can be increased.

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

[0503] By employing the above structure, the oxide semiconductor film 328b becomes the main path for current and is used as the channel region. Furthermore, since the oxide semiconductor films 328a and 328c include one or more of the metal elements contained in the oxide semiconductor film 328b that form the channel region, interface scattering is less likely to occur at the interface between oxide semiconductor films 328a and 328b, or at the interface between oxide semiconductor films 328b and 328c. Therefore, since the movement of charge carriers is not hindered at this interface, the field-effect mobility of the transistor is improved.

[0504] To prevent oxide semiconductor films 328a and 328c from being used as part of the channel region, materials with sufficiently low conductivity are used for oxide semiconductor films 328a and 328c. Alternatively, oxide semiconductor films 328a and 328c are made of materials whose electron affinity (difference between the vacuum level and the conduction band bottom level) is lower than that of oxide semiconductor film 328b and whose conduction band bottom level differs from that of oxide semiconductor film 328b (band shift). Furthermore, to suppress the difference between threshold voltages arising from drain voltage values, oxide semiconductor films 328a and 328c are preferably formed of materials whose conduction band bottom level is closer to the vacuum level than that of oxide semiconductor film 328b. For example, the difference between the conduction band bottom level of oxide semiconductor film 328b and the conduction band bottom level of oxide semiconductor films 328a and 328c is preferably 0.2 eV or more, more preferably 0.5 eV or more.

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

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

[0507] When oxide semiconductor films 328a and 328c are In-M-Zn oxides (M is Al, Ga, Y, or Sn), and the atomic ratio of M is higher than that of In, the band gap of oxide semiconductor films 328a and 328c can be increased while their electron affinity decreases. Therefore, the difference in electron affinity between oxide semiconductor films 328a and 328c and oxide semiconductor film 328b can be controlled according to the ratio of element M. Furthermore, because M is a metallic element with strong bonding with oxygen, oxygen defects are less likely to occur in oxide semiconductor layers where the atomic ratio of M is higher than that of In.

[0508] When In-M-Zn oxide is used as oxide semiconductor films 328a and 328c, the ratio of In to M (excluding Zn and O) is preferably: the atomic percentage of In is less than 50 atomic%, and the atomic percentage of M is greater than 50 atomic%, more preferably: the atomic percentage of In is less than 25 atomic%, and the atomic percentage of M is greater than 75 atomic%. Additionally, gallium oxide films can also be used as oxide semiconductor films 328a and 328c.

[0509] Furthermore, when the oxide semiconductor films 328a, 328b, and 328c are In-M-Zn oxides, the ratio of the number of M atoms in oxide semiconductor films 328a and 328c is greater than the ratio of the number of M atoms in oxide semiconductor film 328b. Typically, the ratio of the number of M atoms in oxide semiconductor films 328a and 328c is 1.5 times or more, preferably 2 times or more, and more preferably 3 times or more.

[0510] Furthermore, when the oxide semiconductor films 328a, 328b, and 328c are In-M-Zn oxides, and the atomic ratio of oxide semiconductor film 328b is In:M:Zn = x1:y1:z1, and the atomic ratio of oxide semiconductor films 328a and 328c is In:M:Zn = x2:y2:z2, y2 / x2 is greater than y1 / x1. Preferably, y2 / x2 is at least 1.5 times y1 / x1, more preferably at least 2 times y1 / x1, and even more preferably at least 3 times or 4 times y1 / x1. In this case, y1 in oxide semiconductor film 328b is preferably at least x1, and the transistor including oxide semiconductor film 328b can have stable electrical characteristics. However, when y1 is at least 3 times x1, the field-effect mobility of the transistor including oxide semiconductor film 328b decreases. Therefore, y1 is preferably less than 3 times x1.

[0511] When the oxide semiconductor film 328b is an In-M-Zn oxide, and the atomic ratio of the metal elements in the target material used to form the oxide semiconductor film 328b is In:M:Zn = x1:y1:z1, x1 / y1 is preferably 1 / 3 or more and 6 or less, more preferably 1 or more and 6 or less, and z1 / y1 is preferably 1 / 3 or more and 6 or less, more preferably 1 or more and 6 or less. Note that when z1 / y1 is 1 or more and 6 or less, it is easy to form the oxide semiconductor film 328b as CAAC-OS (described later). Typical examples of the atomic ratio of the metal elements in the target material include In:M:Zn = 4:2:4.1, In:M:Zn = 1:1:1.2, and In:M:Zn = 3:1:2.

[0512] When the oxide semiconductor films 328a and 328c are In-M-Zn oxides, and the atomic ratio of the metal elements in the target material used to form the oxide semiconductor films 328a and 328c is In:M:Zn = x2:y2:z2, x2 / y2 < x1 / y1, and z2 / y2 is preferably 1 / 3 or more and 6 or less, more preferably 1 or more and 6 or less. When the atomic ratio of M is higher than that of In, the band gap of the oxide semiconductor films 328a and 328c can be widened and their electron affinity can be reduced, so y2 / x2 is preferably 3 or more or 4 or more. Typical examples of the atomic ratio of metal elements in a target material 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] Furthermore, when the oxide semiconductor films 328a and 328c are In-M oxides, if M does not contain divalent metal atoms (e.g., zinc), oxide semiconductor films 328a and 328c without a spinel-type crystal structure can be formed. For example, In-Ga oxide films can be used as oxide semiconductor films 328a and 328c. This In-Ga oxide film can be formed, for example, by sputtering using an In-Ga metal oxide target (In:Ga = 7:93). In order to form oxide semiconductor films 328a and 328c by sputtering using DC discharge, assuming the In:M atomic ratio is x:y, it is preferable that y / (x+y) is 0.96 or less, more preferably 0.95 or less, and for example, 0.93.

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

[0515] exist FIG. 36A and FIG. 36B to FIG. 45A The oxide semiconductor film 328 of transistor Tr2 has a two-layer stacked structure or a three-layer stacked structure, and the oxide semiconductor film 308 of transistor Tr1 can also have the same structure.

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

[0517] <3-8. Manufacturing Method of Semiconductor Devices>

[0518] Next, refer to FIG. 45B and FIG. 36A and FIG. 37A A method for manufacturing a semiconductor device 300 according to one aspect of the present invention will be described.

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

[0520] First, an insulating film 306 is formed on a substrate 302, and an oxide semiconductor film is formed on the insulating film 306. Then, the oxide semiconductor film is processed into islands, thereby forming an oxide semiconductor film 308 (see reference). FIG. 37A and FIG. 37B ).

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

[0522] An insulating film 306 can be formed by appropriately utilizing sputtering, CVD, evaporation, pulsed laser deposition (PLD), printing, or coating methods. 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 306 using a PECVD apparatus.

[0523] After forming the insulating film 306, oxygen can be added to the insulating film 306. The oxygen added to the insulating film 306 can be oxygen free radicals, oxygen atoms, oxygen atom ions, oxygen molecular ions, etc. When adding oxygen, ion doping, ion implantation, plasma treatment, etc., can be used. Alternatively, a film that inhibits oxygen desorption can be formed on the insulating film 306, and then oxygen can be added to the insulating film 306 through this film.

[0524] The aforementioned membrane that inhibits oxygen desorption can be formed using the following conductive materials: metal elements selected from indium, zinc, gallium, tin, aluminum, chromium, tantalum, titanium, molybdenum, nickel, iron, cobalt, and tungsten; alloys containing the aforementioned metal elements as components; alloys containing combinations of the aforementioned metal elements; metal nitrides containing the aforementioned metal elements; metal oxides containing the aforementioned metal elements; and metal nitrides containing the aforementioned metal elements.

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

[0526] The oxide semiconductor film 308 can be formed by sputtering, coating, pulsed laser evaporation, laser ablation, thermal CVD, etc. The oxide semiconductor film 308 can be processed by forming a mask on the oxide semiconductor film using a photolithography process, and then using the mask to etch a portion of the oxide semiconductor film. Alternatively, the oxide semiconductor film 308, which is isolated from each other, can be directly formed on the insulating film 306 using a printing method.

[0527] When forming oxide semiconductor films by sputtering, RF power supplies, AC power supplies, DC power supplies, etc., can be appropriately used as power supplies for generating plasma. Rare gases (typically argon), oxygen, or mixtures of rare gases and oxygen can be appropriately used as sputtering gases for forming oxide semiconductor films. In the mixture of rare gases and oxygen, it is preferable to increase the oxygen ratio relative to the rare gases.

[0528] To improve the crystallinity of oxide semiconductor films, for example, formed by sputtering, it is preferable to form oxide semiconductor films at substrate temperatures of 150°C or higher and 750°C or lower, 150°C or higher and 450°C or lower, or 200°C or higher and 350°C or lower.

[0529] In this embodiment, as the oxide semiconductor film 308, an In-Ga-Zn metal oxide (In∶Ga∶Zn=4∶2∶4.1 [atomic number ratio]) is used as the sputtering target to form an oxide semiconductor film with a thickness of 40 nm.

[0530] After the oxide semiconductor film 308 is formed, it can also be dehydrogenated or dehydrated by heat treatment. The typical temperature for heat treatment is above 150°C and below the strain point of the substrate, above 250°C and below 450°C, or above 300°C and below 450°C.

[0531] The heating process can be performed in an atmosphere containing rare gases such as helium, neon, argon, xenon, and krypton, or an inert gas atmosphere containing nitrogen. Alternatively, it can be performed after heating in an inert gas atmosphere, followed by heating in an oxygen atmosphere. Preferably, the aforementioned inert gas atmosphere and oxygen atmosphere do not contain hydrogen, water, or the like. The processing time can be more than 3 minutes and less than 24 hours.

[0532] This heat treatment can be performed using an electric furnace, an RTA device, or similar equipment. By using an RTA device, heat treatment can be carried out at a temperature above the strain point of the substrate within a short time. This shortens the heat treatment time.

[0533] The oxide semiconductor film is formed during heating, or heated after the oxide semiconductor film is formed. Therefore, the hydrogen concentration in the oxide semiconductor film, as measured by secondary ion mass spectrometry, can be as high as 5 × 10⁻⁶. 19 atoms / cm 3 Below, 1×10 19 atoms / cm 3 Below, 5×10 18 atoms / cm 3 Below, 1×10 18 atoms / cm 3Below, 5×10 17 atoms / cm 3 Below or 1×10 16 atoms / cm 3 the following.

[0534] Next, an insulating film and a conductive film are formed on the insulating film 306 and the oxide semiconductor film 308, and processed into island shapes, thereby forming the insulating film 310 and the conductive film 320 (see reference). FIG. 38A and FIG. 38B ).

[0535] As the insulating film 310, a silicon oxide film or a silicon oxynitride film can be formed using the PECVD method. In this case, a silicon-containing deposition gas and an oxidizing gas are preferably used as the source gas. Typical examples of silicon-containing deposition gases include silanes, disilanes, propanes, and fluorinated silanes. Examples of oxidizing gases include oxygen, ozone, nitrous oxide, and nitrogen dioxide.

[0536] As the insulating film 310, a silicon oxynitride film with few defects can be formed by PECVD under the following conditions: the flow rate of the oxidizing gas is greater than 20 times and less than 100 times or greater than 40 times and less than 80 times the flow rate of the deposition gas; the pressure in the processing chamber is less than 100 Pa or less than 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 in the evacuated processing chamber of the PECVD apparatus is kept at a temperature of 280°C or higher and 400°C or lower, a source gas is introduced into the processing chamber and the pressure in the processing chamber is set to 20 Pa or higher and 250 Pa or lower, preferably 100 Pa or higher and 250 Pa or lower, and high-frequency power is supplied to the electrodes in the processing chamber.

[0538] The insulating film 310 can be formed using a microwave-based plasma CVD method. Microwaves refer to waves in the frequency range of 300 MHz to 300 GHz. In microwaves, electron temperatures are low and electron energies are small. Furthermore, a smaller proportion of the supplied power is used to accelerate electrons, thus allowing more power to be used for the dissociation and ionization of molecules. Therefore, high-density plasma (high-density plasma) can be excited. Consequently, the insulating film 310 with fewer defects can be formed due to the minimal damage caused by the plasma to the formation surface and deposits.

[0539] Alternatively, the insulating film 310 can be formed using a CVD method employing organosilane gases. As organosilane gases, the following silicon-containing compounds can be used: 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), etc. By utilizing a CVD method employing organosilane gases, an insulating film 310 with high coverage can be formed.

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

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

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

[0543] Furthermore, the conductive film 320 can be formed using the same material as the oxide semiconductor film 308 described above.

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

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

[0546] During the processing of the conductive film 320 and the insulating film 310, the thickness of the region of the oxide semiconductor film 308 that does not overlap with the conductive film 320 sometimes becomes smaller.

[0547] Next, impurity elements are added to the insulating film 306, the oxide semiconductor film 308, and the conductive film 320.

[0548] When adding impurity elements, methods such as ion doping, ion implantation, and plasma treatment can be used. In the case of plasma treatment, plasma generated in a gas atmosphere containing the impurity element can be used to add the impurity element. Plasma can be generated using dry etching equipment, ashing equipment, plasma CVD equipment, or high-density plasma CVD equipment.

[0549] As the source gas for impurity elements, at least one of B₂H₆, PH₃, CH₄, N₂, NH₃, AlH₃, AlCl₃, SiH₄, Si₂H₆, F₂, HF, H₂, and rare gases can be used. Alternatively, at least one of B₂H₆, PH₃, N₂, NH₃, AlH₃, AlCl₃, F₂, HF, and H₂ diluted with a rare gas can be used. By adding at least one of B₂H₆, PH₃, N₂, NH₃, AlH₃, AlCl₃, F₂, HF, and H₂ diluted with a rare gas to the oxide semiconductor film 308 and the conductive film 320, at least one of rare gases, 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, after adding a rare gas to the oxide semiconductor film 308 and the conductive film 320, at least one of B2H6, PH3, CH4, N2, NH3, AlH3, AlCl3, SiH4, Si2H6, F2, HF and H2 may be added to the oxide semiconductor film 308 and the conductive film 320.

[0551] Alternatively, after adding at least one of B2H6, PH3, CH4, N2, NH3, AlH3, AlCl3, SiH4, Si2H6, F2, HF and H2 to the oxide semiconductor film 308 and the conductive film 320, a rare gas may be added to the oxide semiconductor film 308 and the conductive film 320.

[0552] The addition of impurity elements can be controlled by appropriately setting the acceleration voltage and dosage, among other implantation conditions. For example, when adding argon via ion implantation, the acceleration voltage can be above 10 kV and below 100 kV, and the dosage can be 1 × 10⁻⁶ kV. 13 ions / cm 2 Above and 1×10 16 ions / cm 2 For example, 1×10 14 ions / cm 2 When adding phosphorus ions via ion implantation, the accelerating voltage can be 30 kV and the dose can be 1 × 10⁻⁶. 13 ions / cm 2 Above and 5×10 16 ions / cm 2 For example, 1×10 15 ions / cm 2 .

[0553] In this embodiment, argon is added as an impurity element to the oxide semiconductor film 308 and the conductive film 320 using a doping device. Note that this embodiment is not limited to the above example of adding argon as an impurity element; for example, nitrogen may be added, or the process of adding an impurity element may be omitted.

[0554] Next, an insulating film 314 is formed on 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 contacts the insulating film 314 and is used as the source region 308s and the drain region 308d. The oxide semiconductor film 308 that does not contact the insulating film 314, in other words, the oxide semiconductor film 308 that contacts the insulating film 310, is used as the channel region 308i. Thus, an oxide semiconductor film 308 including the channel region 308i, the source region 308s, and the drain region 308d is formed (see reference). FIG. 38A and FIG. 38B ).

[0555] Furthermore, the insulating film 314 can be formed using materials suitable for use as insulating films 314. In this embodiment, a silicon nitride film with a thickness of 100 nm is formed as the insulating film 314 using a PECVD apparatus.

[0556] By using a silicon nitride film as an insulating film 314, hydrogen and / or nitrogen in the silicon nitride film enter the conductive film 320, the source region 308s, and the drain region 308d that are in contact with the insulating film 314. Therefore, the carrier density of the conductive film 320, the source region 308s, and the drain region 308d can be improved.

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

[0558] The insulating film 316 can be formed using materials suitable for use in insulating films 316. In this embodiment, the insulating film 316 is a silicon oxynitride film with a thickness of 300 nm formed using a PECVD apparatus.

[0559] Next, a mask is formed at the desired location on the insulating film 316 using a photolithography process. Then, a portion of the insulating film 316 and the insulating film 314 are etched to form an opening 341a reaching the source region 308s and an opening 341b reaching the drain region 308d (see reference). FIG. 38A and FIG. 38B ).

[0560] As a method for etching insulating films 316 and 314, wet etching and / or dry etching can be appropriately used. In this embodiment, dry etching is used to process insulating films 316 and 314.

[0561] Next, a conductive film is formed on the insulating film 316 by filling openings 341a and 341b, and a mask is formed at the desired location by a photolithography process. Then, a portion of the conductive film is etched to form conductive films 312a and 312b (see reference). FIG. 39A and FIG. 39B ).

[0562] The conductive films 312a and 312b can be formed using materials suitable for use as conductive films 312a and 312b. In this embodiment, as conductive films 312a and 312b, a stack of 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 is formed using a sputtering apparatus.

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

[0564] The transistor Tr1 can be manufactured through the above process.

[0565] Additionally, the films or layers included in the transistor Tr1 (e.g., insulating films, oxide semiconductor films, conductive films) can be formed by sputtering, chemical vapor deposition (CVD), vacuum evaporation, pulsed laser deposition (PLD), or ALD (atomic layer deposition). Alternatively, they can be formed using coating or printing methods. While sputtering and plasma-enhanced chemical vapor deposition (PECVD) are typical examples of film formation methods, thermal CVD methods can also be used. MOCVD (metal-organic chemical vapor deposition) is an example of a thermal CVD method.

[0566] Film deposition via thermal CVD can be performed by simultaneously supplying a source gas and an oxidant into a processing chamber whose pressure is set to atmospheric pressure or reduced pressure, and allowing the source gas and oxidant to react with each other near or on the substrate. Thus, no plasma is generated in film deposition using thermal CVD, thereby offering the advantage of avoiding defects caused by plasma damage.

[0567] Film formation using the ALD method can be performed as follows: a source gas for the reaction is introduced into a processing chamber whose pressure is set to atmospheric pressure or reduced pressure, and a reaction occurs; this process is then repeated in sequence. Alternatively, an inert gas (e.g., argon or nitrogen) can be introduced as a carrier gas along with the source gas. For example, two or more source gases can be supplied sequentially into the processing chamber. In this case, an inert gas is introduced between the reaction of the first source gas and the introduction of the second source gas to prevent mixing of the source gases. Alternatively, the first source gas can be evacuated by vacuum degassing instead of introducing an inert gas, followed by the introduction of the second source gas. The first source gas adheres to the substrate surface and reacts to form a first layer; subsequently, the introduced second source gas adheres to and reacts to form a second layer on the first layer, thereby forming a thin film. By repeatedly introducing the gas in this sequence until the desired thickness is obtained, a thin film with good step coverage can be formed. The thickness of the thin film can be precisely adjusted according to the number of times the gas is repeatedly introduced; therefore, the ALD method is suitable for the fabrication of micro-FETs.

[0568] Various films, including conductive films, insulating films, oxide semiconductor films, and metal oxide films, can be formed using isothermal CVD methods such as MOCVD. For example, when forming an In-Ga-Zn-O film, trimethylindium (In(CH3)3), trimethylgallium (Ga(CH3)3), and dimethylzinc (Zn(CH3)2) are used. However, this combination is not limited to these specific combinations; triethylgallium (Ga(C2H5)3) can be used instead of trimethylgallium, and diethylzinc (Zn(C2H5)2) can be used instead of dimethylzinc.

[0569] For example, when forming a hafnium oxide film using an ALD film-forming apparatus, two gases are used: ozone (O3) as an oxidant; and a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor (hafnium alkoxide, tetradimethylammonium hafnium (TDMAH, Hf[N(CH3)2]4) or tetra(ethylmethylammonium)hafnium, etc.).

[0570] For example, when forming an alumina film using an ALD (Alternating Discharge) film-forming apparatus, two gases are used: H2O as an oxidant; and a source gas obtained by vaporizing a liquid containing a solvent and an aluminum precursor (e.g., trimethylaluminum (TMA, Al(CH3)3)). Examples of other materials include tris(dimethylammonium)aluminum, triisobutylaluminum, and aluminum tris(2,2,6,6-tetramethyl-3,5-heptadecyl)one.

[0571] For example, when forming a silicon oxide film using an ALD method film-forming apparatus, hexachlorosilane is attached to the film-forming surface, and free radicals of oxidizing gases (O2, nitrous oxide) are supplied to react with the attached material.

[0572] For example, when forming a tungsten film using an ALD (Alternating Discharge) method film deposition apparatus, WF6 gas and B2H6 gas are introduced sequentially to form an initial tungsten film, and then WF6 gas and H2 gas are used to form the final tungsten film. Note that SiH4 gas can also be used instead of B2H6 gas.

[0573] For example, when forming oxide semiconductor films such as In-Ga-Zn-O films using an ALD (Alternating Deposition) apparatus, the In-O layer is formed using In(CH3)3 gas and O3 gas, the Ga-O layer is formed using Ga(CH3)3 gas and O3 gas, and then the Zn-O layer is formed using Zn(CH3)2 gas and O3 gas. Note that the order of these layers is not limited to the example above. Furthermore, these gases can also be used to form mixed compound layers such as In-Ga-O layers, In-Zn-O layers, Ga-Zn-O layers, etc. Although H2O gas obtained by bubbling with an inert gas such as Ar can be used instead of O3 gas, it is preferable to use O3 gas that does not contain H.

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

[0575] An insulating film 318 can be formed by appropriately utilizing sputtering, CVD, evaporation, pulsed laser deposition (PLD), printing, or coating methods. 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 using a PECVD apparatus.

[0576] After forming the insulating film 318, oxygen can also be added to the insulating film 318. Examples of oxygen added to the insulating film 318 include oxygen free radicals, oxygen atoms, oxygen atom ions, and oxygen molecular ions. Oxygen can be added using ion doping, ion implantation, plasma treatment, etc. Alternatively, a film that inhibits oxygen desorption can be formed on the insulating film, and then oxygen can be added to the insulating film 318 through this film.

[0577] The aforementioned membrane that inhibits oxygen desorption can be formed using the following conductive materials: metal elements selected from indium, zinc, gallium, tin, aluminum, chromium, tantalum, titanium, molybdenum, nickel, iron, cobalt, and tungsten; alloys containing the aforementioned metal elements as components; alloys containing combinations of the aforementioned metal elements; metal nitrides containing the aforementioned metal elements; metal oxides containing the aforementioned metal elements; and metal nitrides containing the aforementioned metal elements.

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

[0579] Furthermore, the insulating film 318 may have a stacked structure of silicon nitride films. Specifically, the silicon nitride film may have a three-layer structure consisting of a first silicon nitride film, a second silicon nitride film, and a third silicon nitride film. An example of this three-layer structure is as follows.

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

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

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

[0583] Alternatively, 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 below.

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

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

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

[0587] In this embodiment, an oxide semiconductor film is formed by sputtering using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). The substrate temperature during the formation of the oxide semiconductor film is 170°C. Oxygen gas with a flow rate of 60 sccm and argon gas with a flow rate of 140 sccm are used as the film-forming gases during the formation of the oxide semiconductor film. The oxide semiconductor film is then processed into a desired shape, thereby forming an island-shaped oxide semiconductor film 328. Furthermore, a wet etching apparatus is used during the formation of the oxide semiconductor film.

[0588] Next, conductive films are formed on the insulating film 318 and the oxide semiconductor film 328, and processed into desired shapes, thereby forming conductive films 322a and 322b. Then, insulating films 324 and 326 (see reference) are formed on the insulating film 318, the oxide semiconductor film 328, and the conductive films 322a and 322b. FIG. 41A and FIG. 41B ).

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

[0590] After forming the conductive films 322a and 322b, the surface of the oxide semiconductor film 328 (on the back channel side) can also be washed. This washing can be performed, for example, using an etchant such as an aqueous solution of phosphoric acid. By washing, impurities (e.g., elements contained in the conductive films 322a and 322b) adhering to the surface of the oxide semiconductor film 328 can be removed. Note that this washing is not necessarily required and may be omitted depending on the circumstances.

[0591] During the formation of conductive films 322a and 322b and / or the washing process described above, the thickness of the region of oxide semiconductor film 328 not covered by conductive films 322a and 322b sometimes becomes thinner.

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

[0593] Preferably, after forming the insulating film 324, the insulating film 326 is continuously formed without exposure to the atmosphere. After forming the insulating film 324, the insulating film 326 is continuously formed by adjusting at least one of the source gas flow rate, pressure, high-frequency power, and substrate temperature without exposure to the atmosphere. This reduces the concentration of impurities originating from the atmosphere at the interface between the insulating films 324 and 326, and allows oxygen in the insulating films 324 and 326 to move into the oxide semiconductor film 328, thereby reducing the amount of oxygen defects in the oxide semiconductor film 328.

[0594] In this embodiment, as the insulating film 324, a silicon oxynitride film is formed using PECVD under the following conditions: the temperature of the substrate 302 is maintained at 220°C; silane with a flow rate of 50 sccm and nitrous oxide with a flow rate of 2000 sccm are used as the source gases; the pressure inside the processing chamber is 20 Pa; and a high-frequency power of 100 W (power density of 1.6 × 10⁻⁶) is applied at 13.56 MHz. -2 W / cm 2 It is supplied to the parallel plate electrodes.

[0595] As the insulating film 326, a silicon oxide film or a silicon oxynitride film is formed under the following conditions: the substrate temperature in the processing chamber of the PECVD apparatus, which has been vacuum-evacuated, is maintained at 180°C or higher and 350°C or lower; a source gas is introduced into the processing chamber; the pressure in the processing chamber is set to 100 Pa or higher and 250 Pa or lower, preferably 100 Pa or higher and 200 Pa or lower; and 0.17 W / cm² is supplied to the electrodes disposed in the processing chamber. 2 Above and 0.5W / cm 2 The preferred value is 0.25 W / cm. 2 Above and 0.35W / cm 2 The following are high-frequency power values.

[0596] As the film-forming conditions for the insulating film 326, a high-frequency power with the aforementioned power density is supplied to the reaction chamber at the aforementioned pressure. This improves the decomposition efficiency of the source gas in the plasma, increases oxygen free radicals, and promotes the oxidation of the source gas. Consequently, the oxygen content in the insulating film 326 exceeds its stoichiometric composition. In films formed at substrate temperatures within the aforementioned temperature range, the bonding force between silicon and oxygen is weak. Therefore, a portion of the oxygen in the film is released through subsequent heat treatment processes. Thus, an oxide insulating film with an oxygen content exceeding its stoichiometric composition and a portion of the oxygen released through heating can be formed.

[0597] Furthermore, in the process of forming the insulating film 326, the insulating film 324 is used as a protective film for the oxide semiconductor film 328. Therefore, the insulating film 326 can be formed using high-frequency power with high power density while minimizing damage to the oxide semiconductor film 328.

[0598] Furthermore, in the film formation conditions of insulating film 326, increasing the flow rate of the silicon-containing deposition gas relative to the oxidizing gas can reduce the amount of defects in insulating film 326. Typically, it is possible to form an oxide insulating film with a low amount of defects, wherein the spin density of the signal originating from silicon dangling bonds and appearing at g = 2.001, as measured by ESR, is less than 6 × 10⁻⁶. 17 spins / cm 3 Preferably 3×10 17 spins / cm 3 The following is more preferably 1.5 × 10 17 spins / cm 3 The result is that the reliability of transistor Tr2 can be improved.

[0599] Preferably, a heat treatment (hereinafter referred to as the first heat treatment) is performed after the insulating films 324 and 326 are formed. The first heat treatment can reduce the amount of nitrogen oxides contained in the insulating films 324 and 326. The first heat treatment can also move a portion of the oxygen contained in the insulating films 324 and 326 to the oxide semiconductor film 328, thereby reducing the amount of oxygen defects in the oxide semiconductor film 328.

[0600] The temperature of the first heat treatment is typically below 400°C, preferably below 375°C, and more preferably above 150°C and below 350°C. The first heat treatment can be carried out in an atmosphere of nitrogen, oxygen, ultra-dry air (containing less than 20 ppm of water, preferably less than 1 ppm, and more preferably less than 10 ppb of water), or a rare gas (e.g., argon, helium). Furthermore, it is preferable that the nitrogen, oxygen, ultra-dry air, or rare gas does not contain hydrogen, water, or the like. An electric furnace, an RTA (rapid thermal anneal) apparatus, or the like can be used in this heat treatment.

[0601] Next, openings 382 leading to conductive film 322a are formed in the desired areas of insulating films 324 and 326. Then, conductive film 330 is formed on insulating film 326 and conductive film 322a (see reference). FIG. 42A and FIG. 42B ).

[0602] When forming the opening 382, ​​either a dry etching apparatus or a wet etching apparatus can be used. An ITSO film with a thickness of 100 nm is formed using an oxide (also known as ITSO) target containing indium, tin and silicon (In2O3:SnO2:SiO2 = 85:10:5 [wt%]), which is then processed into an island shape to obtain the conductive film 330.

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

[0604] Next, a laminated film, which forms insulating films 334 and 336, is formed on insulating film 326 and conductive film 330. Then, an opening 384 reaching conductive film 330 is formed in a desired area of ​​the laminated film (see reference). FIG. 43A and FIG. 43B ).

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

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

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

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

[0609] Next, island-shaped insulating films 340 are formed on insulating film 336 and conductive film 338 (see reference). FIG. 30A and FIG. 30B ).

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

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

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

[0613] Through the above manufacturing processes, it is possible to manufacture 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] Furthermore, the transistor Tr1 includes: an insulating film 316 on 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 on the insulating film 316, the conductive film 312a, and the conductive film 312b.

[0623] Transistor Tr2 includes: a conductive film 312b; an insulating film 318 on the conductive film 312b; an oxide semiconductor film 408 on the insulating film 318; an insulating film 410b on the oxide semiconductor film 408; a conductive film 412b on the insulating film 410b; and an insulating film 414 on both the oxide semiconductor film 408 and the conductive film 412b. Similar to the oxide semiconductor film 308, the oxide semiconductor film 408 includes: a channel region 408i overlapping the conductive film 412b and contacting the insulating film 410b; a source region 408s contacting the insulating film 414; and a drain region 408d contacting the insulating film 414.

[0624] In addition, transistor Tr2 includes: an insulating film 416 on insulating film 414; a conductive film 418a disposed on insulating film 416 and electrically connected to oxide semiconductor film 408; and a conductive film 418b disposed on insulating film 416 and electrically connected to oxide semiconductor film 408.

[0625] In addition, such as FIG. 46A and FIG. 46B As shown, oxide semiconductor film 308 and oxide semiconductor film 408 partially overlap each other.

[0626] The oxide semiconductor film 308 may have the same structure as that shown in Embodiment 3. The oxide semiconductor film 408 may have the same structure as that shown in Embodiment 3.

[0627] Therefore, the field-effect mobility of one or both of transistors Tr1 and Tr2 can exceed 10 cm⁻¹. 2 / Vs, preferably, exceeding 30cm 2 / Vs.

[0628] 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.

[0629] FIG. 46A and FIG. 46B The semiconductor device 400 shown can be suitably used in the pixel circuit of a display device. FIG. 46A and FIG. 46B 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... FIG. 31 and FIG. 46A The layout shown can also increase the pixel aperture ratio. Here, ppi is a unit that represents the number of pixels per inch.

[0630] In addition, in the FIG. 46B and FIG. 46A When the semiconductor device 400 shown is used in the pixel circuit of a display device, it can be used with, for example... FIG. 46B The pixel circuit shown has the same structure.

[0631] In FIG. 46A and FIG. 46B When the semiconductor device 400 shown is used for pixels in a display device, 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. 47A and FIG. 47B to FIG. 53A 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.

[0632] 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.

[0633] 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 418a as the source electrode, conductive film 418b as the drain electrode, and conductive film 412b as the second gate electrode. Furthermore, in transistor Tr2, insulating film 318 is used as the first gate insulating film, and insulating film 410b as the second gate insulating film.

[0634] Note that in this specification, etc., insulating film 410b is sometimes referred to as the fourth insulating film.

[0635] An insulating film 336 is provided on the insulating film 416 and the conductive films 418a and 418b. An opening 386 is provided in the insulating film 336 to reach the conductive film 418b. Furthermore, a conductive film 338 is provided on the insulating film 336. In addition, the conductive film 338 is connected to the conductive film 418a in the opening 386.

[0636] In addition, an insulating film 340, an EL layer 342, and a conductive film 344 are disposed on the conductive film 338. The light-emitting element 360 is constituted by the conductive film 338, the EL layer 342, and the conductive film 344.

[0637] Furthermore, although not illustrated, FIG. 53B and FIG. 47A The transistors Tr1 and Tr2 shown can also have the S-channel structure described in Embodiment 3.

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

[0639] 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.

[0640] <4-2. Components of a Semiconductor Device>

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

[0642] [Conductive film]

[0643] The conductive films 412b, 418a, and 418b can be formed using the materials of the conductive films (conductive films 312a, 312b, 322a, 322b, 320, 330, 338, and 344) shown in Embodiment 3. In particular, an oxide conductor (OC) is preferably used as the conductive film 412b 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 the material of the insulating films (insulating films 306, 314, 316, 318, 324, 326, 334, 336, and 340) shown in Embodiment 3.

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

[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 functions to block oxygen, hydrogen, water, alkali metals, alkaline earth metals, etc. Because the oxide semiconductor film 408 is in contact with the insulating film 414, one or both of the hydrogen and nitrogen in the insulating film 414 enter the oxide semiconductor film 408, thereby increasing the carrier density of the oxide semiconductor film 408. Therefore, the region in the oxide semiconductor film 408 that 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 the material of the oxide semiconductor film (oxide semiconductor film 308 and oxide semiconductor film 328) shown in Embodiment 3.

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

[0651] Next, refer to FIG. 48A and FIG. 49A and FIG. 50A A method for manufacturing a semiconductor device 400 according to one aspect of the present invention will be described.

[0652] also, FIG. 51A , FIG. 52A , FIG. 53A, FIG. 47B , FIG. 48B , FIG. 49B and FIG. 50B This is a top view illustrating the manufacturing method of semiconductor device 400. FIG. 51B , FIG. 52B , FIG. 53B , FIG. 36A , FIG. 36B to FIG. 38A , FIG. 38B and FIG. 47A This is a cross-sectional view illustrating the manufacturing method of the semiconductor device 400.

[0653] The manufacturing method for transistor Tr1 can refer to the method described in Embodiment 3. Therefore, the method for forming insulating film 306, oxide semiconductor film 308, insulating film 310, conductive film 320, insulating film 314, insulating film 316, conductive film 312a, conductive film 312b, and insulating film 318 on substrate 302 can refer to Embodiment 3 and... FIG. 47B and FIG. 48A and FIG. 48B .

[0654] Then, an insulating film 318 is formed on the insulating film 316 and the conductive films 312a and 312b. The insulating film 318 can be formed using the same method as in Embodiment 3.

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

[0656] In this embodiment, an oxide semiconductor film is formed by sputtering using an In-Ga-Zn metal oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). The substrate temperature during the formation of the oxide semiconductor film is 170°C. Oxygen gas with a flow rate of 60 sccm and argon gas with a flow rate of 140 sccm are used as the film-forming gases. The oxide semiconductor film is then processed into a desired shape, thereby forming an island-shaped oxide semiconductor film 408. Furthermore, a wet etching apparatus is used during the formation of the oxide semiconductor film.

[0657] Next, a laminated film including an insulating film and a conductive film is formed on the insulating film 318 and the oxide semiconductor film 408. Then, the laminated film is processed into a desired shape to form island-shaped insulating films 410b and island-shaped conductive films 412b (see reference). FIG. 49A and FIG. 49B ).

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

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

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

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

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

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

[0664] Next, conductive films are formed on the insulating film 416 and the oxide semiconductor film 408 by filling the openings 482a and 482b, and these are processed into island shapes, thereby forming conductive films 418a and 418b (see reference). FIG. 51A and FIG. 51B ).

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

[0666] The transistor Tr2 can be manufactured through the above process.

[0667] Next, an insulating film 336 is formed on the insulating film 416 and the conductive films 418a and 418b. Then, the desired area of ​​the insulating film 336 is processed to form an opening 386 reaching the conductive film 418a (see reference). FIG. 52A and FIG. 52B ).

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

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

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

[0671] Next, island-shaped insulating films 340 are formed on insulating film 336 and conductive film 338 (see reference). FIG. 46A and FIG. 46B ).

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

[0673] Next, an EL layer 342 is formed on the conductive film 338, and then a conductive film 344 is formed on the insulating film 340 and the EL layer 342, thereby obtaining the light-emitting element 360 (see reference). FIG. 54 and ​ ).

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

[0675] Through the above manufacturing processes, it is possible to manufacture ​ and ​ The semiconductor device 400 shown.

[0676] The structures and methods shown in this embodiment can be appropriately combined with the structures and methods shown in other embodiments.

[0677] Implementation Method 5

[0678] In this embodiment, refer to ​ , Figures 55A-55D as well as Figure 56 A light-emitting element of a semiconductor device that can be used in one aspect of the present invention will be described.

[0679] <51. Structural Examples of Light-Emitting Elements>

[0680] First, refer to Figure 54 The structure of a light-emitting element in a semiconductor device that can be used in one aspect of the present invention will be described. Figure 54 This is a cross-sectional schematic diagram of the light-emitting element 160.

[0681] Note that one or both inorganic and organic compounds can be used as the light-emitting element 160. As the organic compound used for the light-emitting element 160, either a low-molecular-weight compound or a high-molecular-weight compound can be used. High-molecular-weight compounds are preferred because they have thermal stability and can be easily formed into thin films with excellent uniformity through methods such as coating.

[0682] Figure 54 The light-emitting element 160 shown includes a pair of electrodes (conductive film 138 and 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 shown includes a 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, it is assumed that the conductive films 138 and 144 in a pair of electrodes are used as the anode and cathode, respectively, but the structure of the light-emitting element 160 is not limited to this. For example, a structure in which the conductive films 138 and 144 are used as the cathode and anode, respectively, and the layers between the electrodes are stacked in reverse order can also 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 sequentially from the anode side.

[0685] The structure of EL layer 142 is not limited to Figure 54The structure shown can be any structure that includes at least one of the following: light-emitting layer 150, hole injection layer 151, hole transport layer 152, electron transport layer 153, and electron injection layer 154. Other structures can also be used. The EL layer 142 may also include a functional layer, which may, for example, lower the injection barrier for holes or electrons; improve the transport of holes or electrons; hinder the transport of holes or electrons; or suppress quenching caused by electrodes. Furthermore, the functional layer may be a single layer or a stacked layer.

[0686] Low-molecular-weight compounds or high-molecular-weight compounds can be used in the light-emitting layer 150.

[0687] In this specification, etc., a polymeric compound refers to a compound with a molecular weight distribution and an average molecular weight of 1×10⁻⁶. 3 Up to 1×10 8 Polymers. Low molecular weight compounds are those that do not have a molecular weight distribution and whose average molecular weight is 1 × 10⁻⁶. 4 The following compounds.

[0688] A polymer is a compound composed of one or more constituent units polymerized together. In other words, the constituent unit refers to at least one unit included in the polymer.

[0689] Polymers can also refer to block polymers, random copolymers, alternating copolymers, or graft copolymers, etc.

[0690] When the end groups of a polymer compound have polymerization active groups, the luminescence characteristics and brightness lifetime of the light-emitting element may decrease. Therefore, the end groups of the polymer compound are preferably stable. As such stable end groups, groups that form covalent bonds with the main chain are preferred. Groups that are bonded to aryl or heterocyclic groups via carbon-carbon bonds are particularly preferred.

[0691] When a low-molecular-weight compound is used in the light-emitting layer 150, it is preferable to include a luminescent low-molecular-weight compound as a guest material, in addition to the low-molecular-weight compound used as the host material. In the light-emitting layer 150, the weight ratio of the host material is greater than the weight ratio of the guest material, and the guest material is dispersed in the host material.

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

[0693] In one embodiment of the light-emitting element 160 of the present invention, electrons and holes are injected from the cathode and anode into the EL layer 142, respectively, by applying a voltage between a pair of electrodes (conductive film 138 and conductive film 144), thereby allowing current to flow. The injected electrons and holes recombine to form excitons. The statistical probability of the ratio of singlet excitons to triplet excitons generated due to the recombination of charge carriers (electrons and holes) (hereinafter referred to as the exciton generation probability) is approximately 1:3. Therefore, in the light-emitting element containing a fluorescent compound, the generation rate of singlet excitons that contribute to luminescence is 25%, and the generation rate of triplet excitons that do not contribute to luminescence is 75%. In the light-emitting element containing a phosphorescent compound, both singlet and triplet excitons can contribute to luminescence. Therefore, the light-emitting element containing a phosphorescent compound has higher luminous efficiency than the light-emitting element containing a fluorescent compound, and is therefore preferred.

[0694] Note that an "exciton" refers to a pair of charge carriers (electron and hole). Because excitons possess energy, the material that generates excitons is in an excited state.

[0695] When a polymeric compound is used in the luminescent layer 150, the polymeric compound preferably comprises a backbone having the function of transporting holes (hole transport) and a backbone having the function of transporting electrons (electron transport) as constituent units. Alternatively, the polymeric compound preferably has at least one of a π-electron-rich heteroaromatic backbone and an aromatic amine backbone, as well as a π-electron-deficient heteroaromatic backbone. The aforementioned backbones are bonded to each other directly or through other backbones.

[0696] When a polymer compound contains both a hole-transporting backbone and an electron-transporting backbone, carrier balance can be easily controlled. Therefore, carrier recombination regions can be easily controlled. For this purpose, the molar ratio of the hole-transporting backbone to the electron-transporting backbone is preferably in the range of 1:9 to 9:1. More preferably, the molar ratio of the electron-transporting backbone is higher than that of the hole-transporting backbone.

[0697] In addition to a skeleton with hole transport capability and a skeleton with electron transport capability, polymeric compounds may also contain a luminescent skeleton as a constituent unit. When a polymeric compound has a luminescent skeleton, the composition ratio of the luminescent skeleton to the total constituent units of the polymeric compound is preferably low, specifically, preferably 0.1 mol% or more and 10 mol% or less, more preferably 0.1 mol% or more and 5 mol% or less.

[0698] Furthermore, the bonding directions, bond angles, bond lengths, etc., of the constituent units of the polymer compound used in the light-emitting element 160 sometimes differ. Additionally, the constituent units may have different substituents and different backbones. Furthermore, the polymerization methods of the constituent units may also differ.

[0699] In addition to the polymer compound used as the host material, the luminescent layer 150 may also contain a luminescent low-molecular-weight compound as a guest material. In this case, the luminescent low-molecular-weight compound is dispersed as a guest material within the polymer compound used as the host material, and the weight ratio of the polymer compound is at least greater than that of the luminescent low-molecular-weight compound. The weight ratio of the luminescent low-molecular-weight compound to the polymer compound is preferably 0.1 wt% or more and 10 wt% or less, more preferably 0.1 wt% or more and 5 wt% or less.

[0700] Next, the constituent elements of a light-emitting element according to one aspect of the present invention will be described in detail.

[0701] [Emitting Layer]

[0702] The following describes the materials that can be used in the light-emitting layer 150.

[0703] While there are no particular limitations on the polymeric compounds that can be used for the luminescent layer 150, the polymeric compound preferably contains at least one of a heteroaromatic skeleton and an aromatic skeleton. These skeletons are preferably bonded directly to each other or via arylene or alkylene groups. Note that the skeletons can also be bonded via groups other than arylene and alkylene groups.

[0704] The polymeric compound preferably has one or more skeletons selected from furan, thiophene, and pyrrole, because these skeletons have high stability and reliability. Preferably, it has a pyridine skeleton, a diazine skeleton (pyrazine, pyrimidine, and pyridazine skeletons), and a triazine skeleton. In particular, the diazine and triazine skeletons are stable and have good reliability, and are therefore preferred. For example, the following skeletons can be used: furan skeleton, benzofuran skeleton, dibenzofuran skeleton, benzodifuran skeleton, thiophene skeleton, benzothiophene skeleton, dibenzothiophene skeleton, benzodithiophene skeleton, thiophene-thiophene skeleton, dithiophene-thiophene skeleton, dithiophene-furan skeleton, dithiophene-selenophene skeleton, cyclopentadithiophene skeleton, dithiophene-thiophene skeleton, thiophene-thiophene skeleton, thiophene-thiophene skeleton, dithiophene-thiophene skeleton, dithiophene-thiophene skeleton, thiophene-indole skeleton, thiophene-pyridine skeleton, thiophene-pyrazine skeleton, thiazole skeleton, thiadiazole skeleton, benzothiazole skeleton, benzodithiazole skeleton, oxazole skeleton, oxadiazole skeleton, benzoxazole skeleton, benzene The skeletons include dioxazole, selenophene, benzo[a]selenophene, dibenzo[a]selenophene, benzo[a]diselenophene, selenoloselenophene, indacenothiophene, indacenothiophene, indacenothiophene, indacenothiophene, indacenotselenophene, pyrrole, indole, carbazole, indole[a]carbazole, bicarbazole, pyrrolo[a]pyrrole, 9,10-dihydroacridan, acridinone, phenoxazine, phenothiazine, phenazine, phenazasiline, azepine, and julonidine, among others. For example, quinoline skeletons, naphthidine skeletons, quinoxaline skeletons, quinazoline skeletons, phthalazine skeletons, cyclophosphine skeletons, pteridine skeletons, acridine skeletons, phenanthridine skeletons, phenanthroline skeletons, benzoquinoline skeletons, benzoquinoxaline skeletons, benzoquinazoline skeletons, dibenzoquinoline skeletons, dibenzoquinoxaline skeletons, dibenzoquinazoline skeletons, imidazole skeletons, pyrazole skeletons, triazole skeletons, benzimidazole skeletons, imidazole-pyridine skeletons, purine skeletons, triazolopyrimidine skeletons, triazolopyridine skeletons, indazole skeletons, etc.

[0705] Alternatively, aromatic skeletons can be used instead of the aforementioned heteroaromatic skeletons. Examples of aromatic skeletons include the biphenyl skeleton, the naphthalene skeleton, and the anthracene skeleton. (chrysene) skeleton, phenanthrene skeleton, triphenylene skeleton, fluorene skeleton, spirofluorene skeleton, indole skeleton, dibenzothiophene skeleton.

[0706] Aromatic amine skeletons can be included in polymeric compounds, preferably secondary or tertiary amine skeletons. Triarylamine skeletons are particularly preferred. As the aryl group of the triarylamine skeleton, a substituted or unsubstituted aryl group having 6 to 13 carbon atoms forming the ring is preferred; examples include phenyl, naphthyl, and fluorenyl. Examples include triphenylamine skeletons, phenylenediamine skeletons, naphthylenediamine skeletons, and benzidine skeletons.

[0707] Ketone skeletons, alkoxy skeletons, etc., can be included in polymers.

[0708] In cases where the aforementioned aromatic amine skeleton, heteroaromatic skeleton, and aromatic hydrocarbon skeleton are bonded via arylene or alkylene groups, examples of such arylene or alkylene groups include phenylene, biphenyl diyl, terphenyl diyl, naphthyl, fluorene diyl, anthracene diyl, 9,10-dihydroanthracene diyl, phenanthrene diyl, pyrene diyl, perylene diyl, etc. (chrysene)diyl, alkoxyphenylene, arylvinylene (phenylene vinylene, etc.), and vinylene. In addition, ether bonds, thioether bonds, ester bonds, etc., can also be used.

[0709] The aforementioned aromatic amine skeleton, heteroaromatic skeleton, aromatic hydrocarbon skeleton, arylene group, and alkylene group can all have substituents. As substituents, alkyl, alkoxy, or alkylthio groups with 1 to 20 carbon atoms, cycloalkyl groups with 3 to 20 carbon atoms, substituted or unsubstituted aryl or aryloxy groups with 6 to 18 carbon atoms, or heterocyclic compound groups with 4 to 14 carbon atoms can be selected. Specific examples of alkyl groups with 1 to 20 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl, 2-ethylhexyl, and 3-methylbutyl. Furthermore, specific examples of alkoxy groups with 1 to 20 carbon atoms include methoxy, ethoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, decoxy, dodecyloxy, 2-ethylhexoxy, 3-methylbutoxy, and isopropoxy. In addition, specific examples of alkylthio groups with 1 to 20 carbon atoms include methylthio, ethylthio, butylthio, pentylthio, hexylthio, heptylthio, octylthio, decylthio, laurylthio, 2-ethylhexylthio, 3-methylbutylthio, and isopropylthio. Specific examples of cycloalkyl groups with 3 to 20 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, noradamantyl, adamantyl, homoadamantyl, and tricyclodecyl. Specific examples of aryl groups with 6 to 18 carbon atoms include substituted or unsubstituted phenyl, naphthyl, biphenyl, fluorenyl, anthraceneyl, and pyreneyl. Specific examples of aryloxy groups with 6 to 18 carbon atoms include substituted or unsubstituted alkoxyphenyl, alkylphenoxy, naphthoxy, anthraceneoxy, and pyreneoxy. Specific examples of heterocyclic compounds with 4 to 14 carbon atoms include substituted or unsubstituted thiophene, pyrrole, furanyl, and pyridyl groups. These substituents can bond with each other to form a ring. For example, when two phenyl groups are substituents at the 9-position of the fluorene skeleton, these phenyl groups bond with each other to form a spirofluorene skeleton. Furthermore, unsubstituted groups are advantageous in terms of ease of synthesis and cost of raw materials.

[0710] Examples of the aforementioned polymeric compounds include: polyphenylene oxide (PPV) derivatives such as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene oxide] (abbreviated as MEH-PPV), poly(2,5-dioctyl-1,4-phenylene oxide), etc.; polyfluorene derivatives such as poly(9,9-di-n-octylfluorenyl-2,7-diyl) (abbreviated as PF8), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] (abbreviated as F8BT), poly[(9,9- Di(n-octylfluorene-2,7-diyl)-alt-(2,2'-bithiophene-5,5'-diyl)] (abbreviated as F8T2), poly[(9,9-dioctyl-2,7-divinylenefluorenylene)-alt-(9,10-anthracene)], poly[(9,9-dihexylfluorene-2,7-diyl)-alt-(2,5-dimethyl-1,4-benzene)], etc.; polyalkylthiophene (PAT) derivatives such as poly(3-hexylthiophene-2,5-diyl) (abbreviated as P3HT), polybenzene derivatives, etc. The aforementioned polymers, poly(9-vinylcarbazole) (abbreviated as PVK), poly(2-vinylnaphthalene), and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (abbreviated as PTAA) can also be doped with luminescent low-molecular-weight compounds and used in the luminescent layer.

[0711] There are no particular restrictions on the fluorescent compounds that can be used in the luminescent layer 150, but anthracene derivatives, tetraphenyl derivatives, etc., are preferred. (chrysene) derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridinone derivatives, coumarin derivatives, phenoxazine derivatives, phenothiazine derivatives, etc. For example, substituted or unsubstituted materials as shown below can be used. The above-described substituents can be used as substituents. The substituents are preferably aliphatic hydrocarbon groups, more preferably alkyl groups, and even more preferably branched alkyl groups.

[0712] Examples of this material include: 5,6-bis[4-(10-phenyl-9-anthrayl)phenyl]-2,2'-bipyridine (abbreviated as: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthrayl)biphenyl-4-yl]-2,2'-bipyridine (abbreviated as: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluorene-9-yl)phenyl]pyrene-1,6-diamine (abbreviated as: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene-9-yl)phenyl]pyrene-1,6- Diamine (abbreviated as: 1,6mMemFLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-bis(4-tert-butylphenyl)-pyrene-1,6-diamine (abbreviated as: 1,6tBu-FLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-diphenyl-3,8-dicyclohexylpyrene-1,6-diamine (abbreviated as: ch-1,6FLPAPrn), N,N'-bis[4-(9H-carbazole-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviated as: YG) A2S), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthrayl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-diphenyl-2-anthrayl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthrayl)phenyl]-9H-carbazole-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthrayl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PC) BAPA), N,N”-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviated as: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthrayl)phenyl]-9H-carbazole-3-amine (abbreviated as: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthrayl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as: 2DPAPPA), N,N,N',N',N”,N”',N”'-octaphenyldibenzo[g,p] (chrysene)-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthrayl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthrayl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthrayl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthrayl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthrayl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA) Abbreviations: 2DPABPhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazole-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), coumarin 6, coumarin 545T, N,N'-diphenylquinactone (abbreviation: DPQd), rubrene, 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenylbenzotetraphenyl (abbreviation: TBRb), Nile red, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenylbenzotetraphenyl (abbreviation: BPT), 2-(2-{2-[4-(dimethyl)-2-yl)-2-phenyl-2-yl)-2-phenyl-2-yl)-2-phenyl-2-yl)-2-(2-{2-[4-(dimethyl)-2-yl)-2-yl)-2-phenyl ... [amino]phenyl]vinyl}-6-methyl-4H-pyran-4-ylidene]malononitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinazine-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviation: DCM2), N,N,N',N'-tetra(4-methylphenyl)acronetetraphenyl-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetra(4-methylphenyl)acenaphthene[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-1H,5H-benzo[ij]quinazine-9-yl)vinyl]-4H-pyran-4-ylidene}malonium (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinazine-9-yl)vinyl]-4H-pyran-4-ylidene}malonium (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]vinyl}-4H-pyran-4-ylidene)malonium (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinazine-9-yl]vinyl]-4H-pyran-4-ylidene}malonium (abbreviation: BisDCJTM), 5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene.

[0713] While there are no particular restrictions on the luminescent framework that can be used in polymer compounds, it is preferred to use luminescent frameworks derived from anthracene, benzo[a]benzene, etc. The structural units are aromatic heterocycles with one or two hydrogen atoms removed from their skeletons, such as chrysene, phenanthrene, pyrene, perylene, stilbene, acridinone, coumarin, phenoxazine, and phenothiazine. The aforementioned substituents can be used as substituents. Alternatively, aliphatic hydrocarbon groups can be introduced as substituents, preferably alkyl groups, and more preferably branched alkyl groups.

[0714] As phosphorescent compounds, iridium, rhodium, platinum-based organometallic complexes or metal complexes can be used, with organoiridium complexes, such as ortho-iridium metal complexes, being preferred. Examples of ortho-metallized ligands include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, or isoquinoline ligands. Examples of metal complexes include platinum complexes with porphyrin ligands. For example, substituted or unsubstituted materials as shown below can be used. The aforementioned substituents can be used as substituents.

[0715] Examples of substances exhibiting emission peaks in the blue or green wavelength range include: tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviated as Ir(mpptz-dmp)3), and tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazol)iridium(III) (abbreviated as Ir(M organometallic iridium complexes with a 4H-triazole skeleton, such as tri[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviated as Ir(iPrptz-3b)3) and tri[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviated as Ir(iPr5btz)3); tri[3-methyl- Organometallic iridium complexes with a 1H-triazole skeleton, such as 1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazole]iridium(III) (abbreviated as Ir(Mptz1-mp)3) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole)iridium(III) (abbreviated as Ir(Prptz1-Me)3); organometallic iridium complexes with an imidazole skeleton, such as fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazolium]iridium(III) (abbreviated as Ir(iPrpmi)3) and tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviated as Ir(dmpimpt-Me)3); and bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2’ Iridium(III) tetrakis(1-pyrazolyl)borate (abbreviated as: FIr6), bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2’ Iridium(III)pyridinecarboxylate (abbreviated as FIRPIC), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinium-N,C 2’}Iridium(III)pyridinecarboxylate (abbreviated as: Ir(CF3ppy)2(pic)), bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2’ Organometallic iridium complexes, such as iridium(III)acetylacetone (abbreviated as FIr(acac)), use phenylpyridine derivatives with electron-withdrawing groups as ligands. Among the above metal complexes, organometallic iridium complexes with a 4H-triazole skeleton are particularly preferred due to their high reliability and high luminescence efficiency.

[0716] Examples of substances exhibiting emission peaks in the green or yellow wavelength range include: tris(4-methyl-6-phenylpyrimidine)iridium(III) (abbreviated as Ir(mppm)3), tris(4-tert-butyl-6-phenylpyrimidine)iridium(III) (abbreviated as Ir(tBuppm)3), (acetylacetonate)bis(6-methyl-4-phenylpyrimidine)iridium(III) (abbreviated as Ir(mppm)2(acac)), (acetylacetonate)bis(6-tert-butyl-4-phenylpyrimidine)iridium(III) (abbreviated as Ir(tBuppm)2(acac)), (acetylacetonate)bis[4-(2-norborneol)-6-phenylpyrimidine]iridium(III) (abbreviated as Ir(nbppm)2(acac)), (acetylacetonate)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidine]iridium(III) (abbreviated as Ir(mp) Organometallic iridium complexes with a pyrimidine skeleton, such as (dmppm)2(acac)), (acetylacetonate)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviated as Ir(dmppm-dmp)2(acac)), (acetylacetonate)bis(4,6-diphenylpyrimidinyl)iridium(TTI) (abbreviated as Ir(dppm)2(acac)); organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonate)bis(3,5-dimethyl-2-phenylpyrazine)iridium(III) (abbreviated as Ir(mppr-Me)2(acac)), (acetylacetonate)bis(5-isopropyl-3-methyl-2-phenylpyrazine)iridium(III) (abbreviated as Ir(mppr-iPr)2(acac)); tri(2-phenylpyridine-N,C 2' Iridium(III) (abbreviated as Ir(ppy)3), bis(2-phenylpyridinium-N,C) 2’ Iridium(III) acetylacetone (abbreviated as Ir(ppy)2(acac)), bis(benzo[h]quinoline)iridium(III) acetylacetone (abbreviated as Ir(bzq)2(acac)), tri(benzo[h]quinoline)iridium(III) (abbreviated as Ir(bzq)3), tri(2-phenylquinoline-N,C 2′ Iridium(III) (abbreviated as Ir(pq)3), bis(2-phenylquinoline-N,C) 2’ Organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetone (abbreviated as Ir(pq)2(acac)); bis(2,4-diphenyl-1,3-oxazol-N,C 2’ Iridium(III) acetylacetone (abbreviated as: Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl)phenyl]pyridine-N,C 2’} Iridium(III) acetylacetone (abbreviated as: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazole-N,C 2’ Organometallic iridium complexes such as iridium(III) acetylacetone (abbreviated as Ir(bt)2(acac)) and rare earth metal complexes such as tri(acetylacetone)(monophenanthroline)terbium(III) (abbreviated as Tb(acac)3(Phen)) are preferred. Among the above metal complexes, organometallic iridium complexes with a pyrimidine framework have excellent reliability and luminescent efficiency, and are therefore particularly preferred.

[0717] Examples of substances exhibiting emission peaks in the yellow or red wavelength range include: (di-k-butyrylmethane)bis[4,6-bis(3-methylphenyl)pyrimidinium]iridium(III) (abbreviated as: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinium](di-neopentaylmethane)iridium(III) (abbreviated as: Ir(5mdppm)2(dpm)), and bis[4,6-bis(naphthyl-1-yl)pyrimidinium](di-neopentaylmethane)iridium(III) (abbreviated as: Ir(d1npm)2(dpm)), etc. Organometallic iridium complexes with a pyrimidine skeleton; iridium(III) bis(2,3,5-triphenylpyrazine)iridium(III) (abbreviated as Ir(tppr)2(acac)), bis(2,3,5-triphenylpyrazine)(dinepentylmethane)iridium(III) (abbreviated as Ir(tppr)2(dpm)), iridium(III) bis[2,3-bis(4-fluorophenyl)quinoxaline]iridium(III) (abbreviated as [Ir(Fdpq)2(acac)]), etc., with a pyrazine skeleton; tris(1-phenylisoquinoline-N,C 2’ Iridium (II-I) (abbreviated as: Ir(piq)3), bis(1-phenylisoquinoline-N,C) 2’ Organometallic iridium complexes with a pyridine skeleton, such as iridium(III)acetylacetone (abbreviated as Ir(piq)2(acac)); platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviated as PtOEP); and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenyline)eup(III) (abbreviated as Eu(DBM)3(Phen)) and tris[1-(2-thienylcarbamoyl)-3,3,3-trifluoroacetone](monophenyline)eup(III) (abbreviated as Eu(TTA)3(Phen)). Among the above metal complexes, organometallic iridium complexes with a pyrimidine skeleton are particularly preferred due to their excellent reliability and luminescence efficiency. Additionally, organometallic iridium complexes with a pyrazine skeleton can provide red luminescence with good colorimetry.

[0718] Phosphorescent compounds can be polymers, and preferably, they are polymers comprising iridium, rhodium, or platinum organometallic complexes or metal complexes as constituent units. That is, it is preferable to use structures that have removed one or two hydrogens from iridium, rhodium, or platinum organometallic complexes or metal complexes as constituent units.

[0719] As an organic compound contained in the luminescent layer 150, any material capable of converting triple excitation energy into luminescence can be used. Besides phosphorescent compounds, thermally activated delayed fluorescence (TADF) materials can be cited as examples of such materials. Therefore, the part described as "phosphorescent compound" can also be referred to as "thermally activated delayed fluorescence material." Note that a TADF material is a material with a small energy difference between the triple excitation level and the singlet excitation level, and has the function of converting energy from the triplet excited state to the singlet excited state through anti-system crossing. Therefore, TADF materials can use a small amount of thermal energy to upconvert the triplet excited state to the singlet excited state (i.e., anti-system crossing) and can efficiently exhibit luminescence (fluorescence) from the singlet excited state. The conditions for efficiently obtaining TADF are as follows: the energy difference between the triplet excited state level and the singlet excited state level is preferably greater than 0 eV and less than 0.2 eV, more preferably greater than 0 eV and less than 0.1 eV.

[0720] TADF materials, as thermally activated delayed fluorescence materials, can be, for example, the following materials.

[0721] First, examples include fullerenes or their derivatives, acridine derivatives such as proflavin, and eosin. Other examples include metalloporphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of metalloporphyrin-containing complexes include protoporphyrin-tin fluoride complex (SnF2(ProtoIX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), protoporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCI2OEP).

[0722] As thermally activated delayed fluorescence materials composed of a single material, heterocyclic compounds with π-electron-rich and π-electron-deficient aromatic heterocycles can also be used. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazole-11-yl)-1,3,5-triazine (abbreviated as PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as PCCzPTzn), and 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as PXZ-TRZ) 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviated as PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-oxanthracene-9-one (abbreviated as ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridin)phenyl]sulfone (abbreviated as DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviated as ACRSA). These heterocyclic compounds possess both π-electron-rich and π-electron-deficient aromatic heterocycles, thus exhibiting high electron and hole transport capabilities, making them preferred choices. Furthermore, materials in which π-electron-rich aromatic heterocycles and π-electron-deficient aromatic heterocycles are directly bonded are preferred, because the π-electron-rich aromatic heterocycles have strong donor properties and the π-electron-deficient aromatic heterocycles have strong acceptor properties, and the difference between the singlet and triplet excitation energy levels becomes smaller.

[0723] As materials exhibiting thermally activated delayed fluorescence, a combination of two materials forming an exciplex can also be used. Preferably, the combination of the aforementioned hole-transporting material and electron-transporting material is preferred. Specifically, zinc or aluminum metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, phenanthroline derivatives, etc., can be used. Other examples include aromatic amines and carbazole derivatives.

[0724] In addition to the compounds used as host materials and the compounds used as luminescent guest materials, the luminescent layer 150 may also contain other substances. For example, substituted or unsubstituted materials that are hole-transporting and electron-transporting materials can be used. Furthermore, the aforementioned substituents can be used as substituents.

[0725] As a hole transport material, materials with higher hole transport than electron transport can be used, preferably those with a density of 1×10⁻⁶.-6 cm 2 Materials with hole mobility of / Vs or higher can be used. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc., can be used. Furthermore, the aforementioned hole-transporting materials can also be polymeric compounds. Additionally, polymeric compounds containing hole-transporting frameworks, π-electron-rich heteroaromatic frameworks, or aromatic amine frameworks contained in the aforementioned polymeric compounds can also be used.

[0726] Examples of materials with high hole transport properties are aromatic amine compounds, such as N,N'-bis(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (DPA3B), etc.

[0727] Specific examples of carbazole derivatives include 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviated as PCzTPN2), 3-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzPCAl), 3,6-bis[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzPCA2), and 3-[N-(1-naphthyl)-N-(9-phenylcarbazole-3-yl)amino]-9-phenylcarbazole (abbreviated as PCzPCN1), etc.

[0728] Other examples of carbazole derivatives include 4,4'-bis(N-carbazolyl)biphenyl (CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (TCPB), 9-[4-(10-phenyl-9-anthrayl)phenyl]-9H-carbazole (CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.

[0729] Examples of aromatic hydrocarbons are 2-tert-butyl-9,10-bis(2-naphthyl)anthracene (t-BuDNA), 2-tert-butyl-9,10-bis(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (t-BuDBA), 9,10-bis(2-naphthyl)anthracene (DNA), 9,10-diphenylanthracene (DPAnth), 2-tert-butylanthracene (t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (DMNA), 2- Tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-bis(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-bis(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, tetraphenylene, rubrogene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, etc. Other examples are pentaphenylene, phenazine, etc. More preferably, a 1×10 -6 cm 2 Aromatic hydrocarbons with a hole mobility of / Vs or higher and a carbon number of 14 to 42.

[0730] Aromatic hydrocarbons can also have a vinyl skeleton. Examples of aromatic hydrocarbons with a vinyl skeleton include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviated as DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviated as DPVPA).

[0731] Other examples are polymers such as poly(N-vinylcarbazole) (PVK), poly(4-vinyltriphenylamine) (PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (Poly-TPD).

[0732] Examples of materials with high hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), 4,4',4”-tris(carbazole-9-yl)triphenylamine (abbreviated as TCTA), 4,4',4”-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviated as 1'-TNATA), 4,4',4”-tris(N,N-diphenylamino)triphenylamine (abbreviated as TDATA), and 4,4',4”-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviated as MT). DATA), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-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-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4”-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4”-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCCNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazole- 3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazole-3-yl)-N,N'-diphenylphenyl-1,3-diamine (abbreviation: PCA2B), N,N',N”-triphenyl-N,N',N”-tris(9-phenylcarbazole-3-yl)phenyl-1,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazole-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBiF), 9,9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluorene-2-amine (abbreviated as: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluorene-2-amine (abbreviated as: PCBASF), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviated as: PCASF), 2, Aromatic amine compounds such as 7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9'-bifluorene (abbreviated as DPA2SF), N-[4-(9H-carbazole-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviated as YGA1BP), and N,N'-bis[4-(carbazole-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviated as YGA2F). Other examples include 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated as PCPN), 3-[4-(9-phenanthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated as PCPPn), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as PCCP), 1,3-bis(N-carbazolyl)phenyl (abbreviated as mCP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as CzTP), 3,6-bis(9H-carbazol-9-yl)-9-phenyl-9H-carbazole (abbreviated as PhCzGI), 2,8-bis(9H-carbazol-9-yl)-dibenzothiophene (abbreviated as Cz2DBT), and 4-{3-[3-(9-phenyl-9H-fluorene-9-yl)phenyl]phenyl}dibenzofuran (abbreviated as mmDBFFL). Bi-II), 4,4',4”-(benzyl-1,3,5-triyl)tris(dibenzofuran) (abbreviated as: DBF3P-II), 1,3,5-tris(dibenzothiophene-4-yl)-benzene (abbreviated as: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorene-9-yl)phenyl]dibenzothiophene (abbreviated as: DBTFLP-III), 4-[4-(9-phenyl-9H-fluorene-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as: DBTFLP-IV), 4-[3-(triphenyl-2-yl)phenyl]dibenzothiophene (abbreviated as: mDBTPTp-II) and other amine compounds, carbazole compounds, thiophene compounds, furan compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds, etc. The substances described herein mainly have a concentration of 1×10, -6 cm 2 Substances with a hole mobility of / Vs or higher. Note that any substance other than those listed above can be used as long as its hole transport capability is higher than its electron transport capability.

[0733] As an electron transport material, materials with higher electron transport than hole transport can be used, preferably those with a density of 1×10⁻⁶. -6 cm 2 Materials with electron mobilities of / Vs or higher. As materials that readily accept electrons (materials with electron transport properties), π-electron-deficient heteroaromatic compounds such as nitrogen-containing heteroaromatic compounds or metal complexes can be used. Specific examples of metal complexes include those containing quinoline ligands, benzoquinoline ligands, oxazole ligands, and thiazole ligands. Other examples include oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, and pyrimidine derivatives. Furthermore, this electron-transporting material can also be a polymer. Additionally, polymers containing electron-transporting skeletons or π-electron-deficient heteroaromatic skeletons, including those mentioned above, can also be used.

[0734] Examples include metal complexes with quinoline or benzoquinoline skeletons, such as: tris(8-hydroxyquinoline)aluminum(III) (abbreviated: Alq), tris(4-methyl-8-hydroxyquinoline)aluminum(III) (abbreviated: Almq3), bis(10-hydroxybenzo[h]quinoline)beryllium(II) (abbreviated: BeBq2), bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum(III) (abbreviated: RAlq), and bis(8-hydroxyquinoline)zinc(II) (abbreviated: Znq). Additionally, metal complexes with oxazole or thiazole ligands, such as bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviated: ZnPBO) and bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviated: ZnBTZ), can also be used. In addition to this metal complex, 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviated as OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-2-yl)phenyl]-9H-carbazole (abbreviated as CO11), and 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviated as: TAZ), 9-[4-(4,5-diphenyl-4H-1,2,4-triazol-3-yl)phenyl]-9H-carbazole (abbreviation: CzTAZ1), 2,2',2”-(1,3,5-benzyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), phenanthroline (abbreviation: BPhen), copper bath (abbreviation: BCP) and other heterocyclic compounds;2-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophene-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazole-9-yl)biphenyl-9-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq)biphenyl-9-yl] ... [3-(3,9'-bi-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-[3-(3,9'-bi-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mCz) Heterocyclic compounds with a diazine skeleton, such as CzPDBq, 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviated as: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothiophene)phenyl]pyrimidine (abbreviated as: 4,6mDBTP2Pm-II), and 4,6-bis[3-(9H-carbazole-9-yl)phenyl]pyrimidine (abbreviated as: 4,6mCzP2Pm); 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]pyrimidine Heterocyclic compounds with a triazine skeleton, such as phenyl{-4,6-diphenyl-1,3,5-triazine (abbreviated as PCCzPTzn); heterocyclic compounds with a pyridine skeleton, such as 3,5-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviated as 35DCzPPy) and 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviated as TmPyPB); and heteroaromatic compounds, such as 4,4'-bis(5-methylbenzoxazolyl-2-yl)stilbene (abbreviated as BzOs). Among the above heterocyclic compounds, heterocyclic compounds with a diazine skeleton (pyrimidine, pyrazine, pyridazine) or a pyridine skeleton are stable and reliable, and are therefore preferred. In addition, heterocyclic compounds with the above skeletons have high electron transport properties, which also helps to reduce the driving voltage. Alternatively, polymeric compounds such as poly(2,5-pyridindiyl) (abbreviated as PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridin-3,5-diyl)] (abbreviated as PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridin-6,6'-diyl)] (abbreviated as PF-BPy) can also be used. The substances described herein primarily possess a concentration of 1 × 10; -6 cm 2Substances with electron mobility of / Vs or higher. However, any substance other than those mentioned above can be used as long as its electron transport capacity is higher than its hole transport capacity.

[0735] Polymers can also have structures that remove one or two hydrogens from the aforementioned hole-transporting and electron-transporting materials.

[0736] The aforementioned light-emitting layer 150 can be formed using methods such as vapor deposition (including vacuum vapor deposition), inkjet printing, coating, nozzle printing, and gravure printing.

[0737] When a polymer compound is used in the light-emitting layer 150, other materials besides the polymer compound may also be used in the light-emitting layer 150. In this case, the material and the aforementioned polymer compound are preferably dissolved in the same solvent.

[0738] Examples of solvents that can be used in inkjet, coating, nozzle printing, and gravure printing include: chlorinated solvents such as dichloroethane, trichloroethane, chlorobenzene, and dichlorobenzene; ether solvents such as tetrahydrofuran, dioxane, anisole, and methyl anisole; aromatic solvents such as toluene, xylene, mesitylene, ethylbenzene, hexylbenzene, and cyclohexylbenzene; and aliphatic hydrocarbon solvents such as cyclohexane, methylcyclohexane, pentane, hexane, heptane, and octane. Nonane, decane, dodecane, and dicyclohexyl, etc.; ketone solvents such as acetone, methyl ethyl ketone, cyclohexane, benzophenone, and acetophenone, etc.; ester solvents such as ethyl acetate, butyl acetate, ethyl acetate solvent, methyl benzoate, and phenyl acetate, etc.; polyol solvents such as ethylene glycol, glycerol, and hexanediol, etc.; alcohol solvents such as isopropanol and cyclohexanol, etc.; sulfoxide solvents such as dimethyl sulfoxide, etc.; and amide solvents such as methylpyrrolidone and dimethylformamide. One or more materials can be used as solvents.

[0739] The light-emitting layer 150 may have a structure with two or more layers stacked on top of each other. For example, in the case where the light-emitting layer 150 is formed by sequentially stacking a first light-emitting layer and a second light-emitting layer from the hole transport layer side, a material with hole transport properties is used as a polymer compound to form the first light-emitting layer, and a material with electron transport properties is used as a polymer compound to form the second light-emitting layer.

[0740] [Hollow Injection Layer]

[0741] The hole injection layer 151 functions to lower the injection barrier of holes from one of the pair of electrodes (conductive films 138 and 144), thus promoting hole injection, and is formed, for example, using transition metal oxides, phthalocyanine derivatives, or aromatic amines. Examples of transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of phthalocyanine derivatives include phthalocyanine or metallic phthalocyanine. Examples of aromatic amines include benzidine derivatives or phenylene diamine derivatives. Alternatively, polymers such as polythiophene or polyaniline can be used; a typical example is poly(ethylenedioxythiophene) / poly(styrene sulfonic acid) as a self-doped polythiophene. Furthermore, examples include polyvinylcarbazole and its derivatives, and polyarylene compounds and their derivatives having an aromatic amine backbone or a π-electron-rich heteroaromatic backbone in the side chain or main chain.

[0742] As the hole injection layer 151, a layer of composite material comprising a hole-transporting material and a material having the property of receiving electrons from the hole-transporting material can also be used. Alternatively, a stack of a layer comprising a material having electron-receiving properties and a layer comprising a hole-transporting material can also be used. Charge transfer and acceptance can occur between these materials in a stationary state or in the presence of an electric field. Examples of materials having electron-receiving properties include organic acceptors such as quinone dimethyl derivatives, tetrachlorobenzoquinone derivatives, and hexaazatriphenylene derivatives. Specific examples are compounds with electron-withdrawing groups (halogen or cyano groups) such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinone dimethyl (abbreviated: F4-TCNQ), chloroquinone, and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated: HAT-CN). In addition, transition metal oxides, such as oxides of group 4 to group 8 metals, can also be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, etc., can be used. Molybdenum oxide is particularly preferred because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

[0743] As a hole transport material, materials with higher hole transport than electron transport can be used, preferably those with a density of 1×10⁻⁶. -6 cm 2 Materials with a hole mobility of / Vs or higher can be used. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc., can be used as hole transport materials suitable for use in the light-emitting layer 150. Furthermore, the aforementioned hole transport materials can also be polymer compounds.

[0744] Hole transport layer

[0745] Alternatively, a hole transport layer may be provided between the hole injection layer 151 and the light-emitting layer 150. The hole transport layer is a layer containing a hole-transporting material, and the hole-transporting material shown in the example material of the hole injection layer 151 can be used. To enable the hole transport layer 152 to transport holes injected into the hole injection layer 151 to the light-emitting layer 150, the HOMO (highest occupied molecular orbital) energy level of the hole transport layer 152 is preferably the same as or close to the HOMO energy level of the hole injection layer 151.

[0746] As a hole transport material, it is preferable to use a material with a density of 1×10⁻⁶. -6 cm 2 Materials with a hole mobility of / Vs or higher. Note that any material other than those mentioned above can be used, as long as its hole transport capability is higher than its electron transport capability. Layers containing materials with high hole transport capability are not limited to single layers; two or more layers containing the aforementioned materials can also be stacked.

[0747] [Electron transport layer]

[0748] An electron transport layer may also be provided between the light-emitting layer 150 and the electron injection layer. The electron transport layer functions to transport electrons injected from one of the two electrodes (conductive film 138 or conductive film 144) through the electron injection layer 154 to the light-emitting layer 150. As the electron transport material, a material with higher electron transport than hole transport can be used, preferably one with a electron transport capacity of 1×10⁻⁶. -6 cm 2 Materials with an electron mobility of 1 × 10⁻⁶ Vs or higher. As materials that readily accept electrons (materials with electron transport properties), π-electron-deficient heteroaromatic compounds such as nitrogen-containing heteroaromatic compounds or metal complexes can be used. Specifically, examples of electron transport materials suitable for use in the luminescent layer 150 include metal complexes with quinoline ligands, benzoquinoline ligands, oxazole ligands, and thiazole ligands. Furthermore, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, and pyrimidine derivatives can be used. Additionally, polymeric compounds such as polyphenylene oxide, polyfluorene, and their derivatives are preferred. A π-electron mobility of 1 × 10⁻⁶ Vs is preferred. -6 cm 2 Materials with an electron mobility of / Vs or higher. Note that any material other than those mentioned above can be used, as long as its electron transport capability is higher than its hole transport capability. The electron transport layer is not limited to a single layer; it can also consist of two or more layers containing the aforementioned materials.

[0749] A layer for controlling the movement of electron carriers can also be provided between the electron transport layer and the light-emitting layer 150. This layer is formed by adding a small amount of a substance with high electron trapping properties to the aforementioned material with high electron transport properties. By suppressing the movement of electron carriers, the balance of carriers can be adjusted. This structure is very effective in suppressing problems caused by electrons passing through the light-emitting layer (such as a decrease in device lifetime).

[0750] [Electron Injection Layer]

[0751] The electron injection layer 154 facilitates electron injection by lowering the electron injection barrier from the conductive film 144, and can be, for example, a Group 1 metal, a Group 2 metal, or oxides, halides, or carbonates of these metals. Alternatively, a composite material comprising the aforementioned electron transport material and a material having electron-supplying properties to the electron transport material can be used. Examples of materials with electron-supplying properties include Group 1 metals, Group 2 metals, or oxides of these metals. Specifically, lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2), and lithium oxide (LiO) can be used. x Alkali metals, alkaline earth metals, or compounds of these metals can be used. Alternatively, rare earth metal compounds such as erbium fluoride (ErF3) can be used. Electron salts can also be used in the electron injection layer 154. Examples of such electron salts include substances that add electrons at a high concentration to a mixed oxide of calcium and aluminum. Substances suitable for electron transport layers can be used in the electron injection layer 154.

[0752] Alternatively, a composite material containing an organic compound and an electron donor can be used for the electron injection layer 154. This composite material exhibits excellent electron injection and electron transport properties because it generates electrons in the organic compound through the electron donor. In this case, the organic compound is preferably a material with excellent performance in transporting the generated electrons. Specifically, for example, materials forming the electron transport layer as described above (e.g., metal complexes, heteroaromatic compounds) can be used. As the electron donor, a substance exhibiting electron-donating properties to the organic compound can be used. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferred, such as lithium, cesium, magnesium, calcium, erbium, and ytterbium. Additionally, alkali metal oxides or alkaline earth metal oxides are preferred, such as lithium oxides, calcium oxides, and barium oxides. Lewis bases such as magnesium oxide can also be used. Furthermore, organic compounds such as tetrathiofulvalene (TTF) can also be used.

[0753] Furthermore, the aforementioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer can all be formed by methods such as vapor deposition (including vacuum vapor deposition), inkjet printing, coating, nozzle printing, and gravure printing. In addition to the materials mentioned above, inorganic compounds such as quantum dots can also be used as the aforementioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer.

[0754] Examples of materials that can form quantum dots include Group 14 elements, compounds containing multiple Group 14 elements, Group 15 elements, Group 16 elements, compounds of Group 4 to 14 elements and Group 16 elements, compounds of Group 2 elements and Group 16 elements, compounds of Group 13 elements and Group 15 elements, compounds of Group 13 elements and Group 17 elements, compounds of Group 14 elements and Group 15 elements, compounds of Group 11 elements and Group 17 elements, iron oxides, titanium oxides, spinel chalcogenides, and semiconductor clusters.

[0755] Specific examples include cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), zinc selenide (ZnSe), zinc oxide (ZnO), zinc sulfide (ZnS), zinc telluride (ZnTe), mercuric sulfide (HgS), mercuric selenide (HgSe), mercuric telluride (HgTe), indium arsenide (InAs), indium phosphide (InP), gallium arsenide (GaAs), gallium phosphide (GaP), indium nitride (InN), gallium nitride (GaN), indium antimonide (InSb), gallium antimonide (GaSb), aluminum phosphide (AlP), aluminum arsenide (AlAs), aluminum antimonide (AlSb), lead(II) selenide (PbSe), lead(II) telluride (PbTe), and lead(II) sulfide (PbS). Indium selenide (In2Se3), indium telluride (In2Te3), indium sulfide (In2S3), gallium selenide (Ga2Se3), arsenic(III) sulfide (As2S3), arsenic(III) selenide (As2Se3), arsenic(III) telluride (As2Te3), antimony(III) sulfide (Sb2S3), antimony(III) selenide (Sb2Se3), antimony(III) telluride (Sb2Te3), bismuth(III) sulfide (Bi2S3), bismuth(III) selenide (Bi2Se3), bismuth(III) telluride (Bi2Te3), silicon (Si), silicon carbide (SiC), germanium (Ge), tin (Sn), selenium (Se), tellurium (Te), boron (B), carbon (C), phosphorus (P) Boron nitride (BN), boron phosphide (BP), boron arsenide (BAs), aluminum nitride (AlN), aluminum sulfide (Al2S3), barium sulfide (BaS), barium selenide (BaSe), barium telluride (BaTe), calcium sulfide (CaS), calcium selenide (CaSe), calcium telluride (CaTe), beryllium sulfide (BeS), beryllium selenide (BeSe), beryllium telluride (BeTe), magnesium sulfide (MgS), magnesium selenide (MgSe), germanium sulfide (GeS), germanium selenide (GeSe), germanium telluride (GeTe), tin sulfide (IV)(SnS2), tin sulfide (II)(SnS), tin selenide (II)(SnSe), tin telluride (II)(SnTe), lead oxide (II)(PbO) Copper fluoride (I) (CuF), copper chloride (I) (CuCl), copper bromide (I) (CuBr), copper iodide (I) (CuI), copper oxide (I) (Cu2O), copper selenide (I) (Cu2Se), nickel oxide (II) (NiO), cobalt oxide (II) (CoO), cobalt sulfide (II) (CoS), iron tetroxide (Fe3O4), iron sulfide (II) (FeS), manganese oxide (II) (MnO), molybdenum sulfide (IV) (MoS2), vanadium oxide (II) (VO), vanadium oxide (IV) (VO2), tungsten oxide (IV) (WO2), tantalum oxide (V) (Ta2O5), titanium oxide (TiO2, Ti2O5, Ti2O3, Ti5O9, etc.)Zirconia (ZrO2), silicon nitride (Si3N4), germanium nitride (Ge3N4), aluminum oxide (Al2O3), barium titanate (BaTiO3), compounds of zinc cadmium selenide (CdZnSe), compounds of indium arsenide phosphate (InAsP), compounds of cadmium selenide sulfide (CdSeS), compounds of cadmium selenide tellurium (CdSeTe), compounds of zinc cadmium selenide (ZnCdSe), compounds of indium gallium arsenide (InGaAs), compounds of indium gallium selenide (InGaSe), compounds of indium selenide sulfide (InSeS), compounds of copper indium sulfide (e.g., CuInS2), and combinations thereof, but not limited to these. Furthermore, so-called alloy-type quantum dots, whose composition can be expressed in arbitrary ratios, can also be used. For example, because of CdS, x Se 1-x Alloy quantum dots (where x is any number from 0 to 1) can have their emission wavelength changed by altering the ratio of x, making them one of the effective means of obtaining blue emission.

[0756] Quantum dots can be categorized into core-type quantum dots, core-shell quantum dots, and core-multishell quantum dots. When the core is covered...

Claims

1. A semiconductor device comprising a pixel, the pixel comprising: a first transistor comprising: a first semiconductor film comprising a first channel formation region; a first gate electrode over the first semiconductor film; and a first source electrode and a first drain electrode in contact with the first semiconductor film; a second transistor comprising: a second semiconductor film comprising a second channel formation region; a second gate electrode over the second semiconductor film; and a second source electrode and a second drain electrode in contact with the second semiconductor film; and a light emitting element whose first electrode is electrically connected to one of the second source electrode and the second drain electrode, wherein the second semiconductor film is provided over a first insulating film, the second transistor further comprises a third gate electrode under the first insulating film, the first gate electrode and the third gate electrode are provided in different layers, the first transistor further comprises a fourth gate electrode under the first semiconductor film, the first gate electrode and the fourth gate electrode are electrically connected to each other, the one of the second source electrode and the second drain electrode is in contact with the second semiconductor film through an opening provided in a second insulating film, the second insulating film being formed over the second gate electrode, the first channel formation region and the second channel formation region do not overlap with each other, and the first semiconductor film and the second semiconductor film are different in composition from each other.

2. A semiconductor device comprising a pixel, the pixel comprising: a first transistor comprising: a first semiconductor film comprising a first channel formation region; a first gate electrode over the first semiconductor film; and a first source electrode and a first drain electrode in contact with the first semiconductor film; a second transistor comprising: a second semiconductor film comprising a second channel formation region; a second gate electrode over the second semiconductor film; and a second source electrode and a second drain electrode in contact with the second semiconductor film; and a light emitting element whose first electrode is electrically connected to one of the second source electrode and the second drain electrode, wherein the second semiconductor film is provided over a first insulating film, the second transistor further comprises a third gate electrode under the first insulating film, the first gate electrode and the third gate electrode are provided in different layers, the first transistor further comprises a fourth gate electrode under the first semiconductor film, the first gate electrode and the fourth gate electrode are electrically connected to each other, the one of the second source electrode and the second drain electrode is in contact with the second semiconductor film through an opening provided in a second insulating film, the second insulating film being formed over the second gate electrode, the first channel formation region and the second channel formation region do not overlap with each other, and the second semiconductor film contains In, Ga, and Zn.

3. A semiconductor device comprising a pixel, the pixel comprising: a first transistor comprising: a first semiconductor film comprising a first channel formation region; a first gate electrode over the first semiconductor film; and a first source electrode and a first drain electrode in contact with the first semiconductor film; a second transistor including: a second semiconductor film including a second channel formation region; a second gate electrode over the second semiconductor film; and a second source electrode and a second drain electrode in contact with the second semiconductor film; and a light emitting element whose first electrode is electrically connected to one of the second source electrode and the second drain electrode, wherein the second semiconductor film is provided over a first insulating film, the second transistor further includes a third gate electrode under the first insulating film, the third gate electrode overlaps with the second gate electrode, and the second semiconductor film is provided between the second gate electrode and the third gate electrode, the first gate electrode and the third gate electrode are provided in different layers, the first transistor further includes a fourth gate electrode under the first semiconductor film, the one of the second source electrode and the second drain electrode is in contact with the second semiconductor film through an opening provided in a second insulating film, the second insulating film is formed over the second gate electrode, the first channel formation region and the second channel formation region do not overlap with each other, and the first semiconductor film and the second semiconductor film are different in composition from each other.

4. A semiconductor device comprising a pixel, the pixel comprising: a first transistor including: a first semiconductor film including a first channel formation region; a first gate electrode over the first semiconductor film; and a first source electrode and a first drain electrode in contact with the first semiconductor film; a second transistor including: a second semiconductor film including a second channel formation region; a second gate electrode over the second semiconductor film; and a second source electrode and a second drain electrode in contact with the second semiconductor film; and a light emitting element whose first electrode is electrically connected to one of the second source electrode and the second drain electrode, wherein the second semiconductor film is provided over a first insulating film, the second transistor further includes a third gate electrode under the first insulating film, the third gate electrode overlaps with the second gate electrode, and the second semiconductor film is provided between the second gate electrode and the third gate electrode, the first gate electrode and the third gate electrode are provided in different layers, the first transistor further includes a fourth gate electrode under the first semiconductor film, the one of the second source electrode and the second drain electrode is in contact with the second semiconductor film through an opening provided in a second insulating film, the second insulating film is formed over the second gate electrode, the first channel formation region and the second channel formation region do not overlap with each other, and the second semiconductor film contains In, Ga, and Zn.

5. The semiconductor device according to any one of Claims 1 to 4, further comprising a capacitor, wherein, a first electrode of the capacitor is electrically connected to the first electrode of the light emitting element.

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