Semiconductor device and method for manufacturing semiconductor device

Abstract

A micro transistor is provided. Provided is a transistor having a large on-state current. The semiconductor device includes a semiconductor layer, a first conductive layer, a second conductive layer, a third conductive layer, a first insulating layer, and a second insulating layer, the first insulating layer being located on the first conductive layer, the second conductive layer being located on the first insulating layer, the semiconductor layer being in contact with a top surface of the first conductive layer, a top surface and a side surface of the second conductive layer, and a side surface of the first insulating layer, the second insulating layer is located on the semiconductor layer, the third conductive layer is located on the second insulating layer and overlaps with the semiconductor layer via the second insulating layer, the semiconductor layer includes a first region in contact with a top surface of the first conductive layer and a second region in contact with a top surface of the second conductive layer, the first region and the second region contain a first element, and the second element contains a second element. The first element is boron or phosphorus.

Description

TECHNICAL FIELD

[0001] One embodiment of the present application relates to a semiconductor device and a manufacturing method thereof. One embodiment of the present application relates to a transistor and a manufacturing method thereof. One embodiment of the present application relates to a display device including a semiconductor device.

[0002] Note that one embodiment of the present application is not limited to the technical field described above. Examples of a technical field to which one embodiment of the present application pertains are a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device (e.g., a touch sensor), an input-output device (e.g., a touch panel), and a driving method or a manufacturing method thereof.

[0003] In this specification and the like, a semiconductor device generally means a device that utilizes semiconductor characteristics and includes a circuit including a semiconductor element (a transistor, a diode, a photodiode, and the like) and a device including the circuit. Furthermore, a semiconductor device means all devices that can function by utilizing semiconductor characteristics. For example, a semiconductor device includes an integrated circuit, a chip including an integrated circuit, and an electronic component in which a chip is mounted in a package. Furthermore, a memory device, a display device, a light-emitting device, a lighting device, and an electronic device themselves are semiconductor devices, and each include a semiconductor device in some cases. BACKGROUND

[0004] A semiconductor device including a transistor is widely used in electronic devices. For example, by reducing the area occupied by a transistor in a display device, the pixel size can be reduced to achieve high definition. Thus, there is a demand for miniaturization of transistors.

[0005] As a device requiring a high-definition display device, development of a device for virtual reality (VR), augmented reality (AR), substitutional reality (SR), or mixed reality (MR) is active, for example.

[0006] As a display device, development of a light-emitting device including an organic EL (Electro Luminescence) element or a light-emitting diode (LED) is active, for example.

[0007] A high-definition display device using an organic EL element is disclosed in Patent Document 1.

[0008] [Prior Art Documents]

[0009] [Patent Documents]

[0010] [Patent Document 1] International Patent Application Publication No. 2016 / 038508 SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] An object of one embodiment of the present application is to provide a micro transistor. Another object of one embodiment of the present application is to provide a transistor with a small channel length. Another object of one embodiment of the present application is to provide a transistor with a large on-state current. Another object of one embodiment of the present application is to provide a transistor with a good electric characteristic. Another object of one embodiment of the present application is to provide a semiconductor device with a small occupied area. Another object of one embodiment of the present application is to provide a semiconductor device with a low wiring resistance. Another object of one embodiment of the present application is to provide a semiconductor device or a display device with low power consumption. Another object of one embodiment of the present application is to provide a transistor, a semiconductor device, or a display device with high reliability. Another object of one embodiment of the present application is to provide a display device which is easily high-definition. Another object of one embodiment of the present application is to provide a method for manufacturing a semiconductor device or a display device with high productivity. Another object of one embodiment of the present application is to provide a novel transistor, a semiconductor device, a display device, and a method for manufacturing the same.

[0013] Note that the description of these objects does not preclude the existence of other objects. One embodiment of the present application does not necessarily achieve all the above-described objects. An object other than the above can be extracted from the description, drawings, claims, and the like.

[0014] MEANS FOR SOLVING PROBLEMS

[0015] One embodiment of the present application is a semiconductor device including a semiconductor layer, a first conductive layer, a second conductive layer, a third conductive layer, a first insulating layer, and a second insulating layer, in which the first insulating layer is positioned over the first conductive layer, the second conductive layer is positioned over the first insulating layer, the semiconductor layer is in contact with a top surface of the first conductive layer, a top surface and a side surface of the second conductive layer, and a side surface of the first insulating layer, the second insulating layer is positioned over the semiconductor layer, the third conductive layer is positioned over the second insulating layer and overlaps with the semiconductor layer with the second insulating layer interposed therebetween, the semiconductor layer includes a first region in contact with the top surface of the first conductive layer and a second region in contact with the top surface of the second conductive layer, and the first region and the second region contain a first element, and the first element is boron or phosphorus.

[0016] Further, one embodiment of the present application is a semiconductor device including a semiconductor layer, a first conductive layer, a second conductive layer, a third conductive layer, a first insulating layer, and a second insulating layer, in which the first insulating layer is positioned on the first conductive layer and has a first opening portion, the second conductive layer is positioned on the first insulating layer and has a second opening portion overlapping with the first opening portion, the semiconductor layer is in contact with a top surface of the first conductive layer through the first opening portion and the second opening portion and is in contact with a top surface of the second conductive layer and side surfaces of the second opening portion and side surfaces of the first opening portion of the first insulating layer, respectively, the second insulating layer is positioned on the semiconductor layer, the third conductive layer is positioned on the second insulating layer and overlaps with the semiconductor layer through the second insulating layer, the semiconductor layer includes a first region in contact with the top surface of the first conductive layer and a second region in contact with the top surface of the second conductive layer, and the first region and the second region contain a first element, and the first element is boron or phosphorus. It is preferable that the semiconductor device include the first insulating layer on a substrate, and an angle formed by the side surfaces of the first opening portion of the first insulating layer and a top surface of the substrate be greater than or equal to 65 degrees and less than or equal to 90 degrees.

[0017] The second insulating layer preferably contains the first element.

[0018] It is preferable that the first region and the second region contain hydrogen and the first element be boron.

[0019] It is preferable that the semiconductor layer include a third region in contact with a side surface of the first insulating layer, the first region include a region in which a concentration of the first element is higher than that in the third region, and the second region include a region in which the concentration of the first element is higher than that in the third region.

[0020] It is preferable that the first region include a region in which a hydrogen concentration is higher than that in the third region, and the second region include a region in which the hydrogen concentration is higher than that in the third region.

[0021] The semiconductor layer preferably contains a metal oxide in a channel formation region.

[0022] It is preferable that the first insulating layer include a first layer containing nitrogen and silicon over the first conductive layer, a second layer containing oxygen and silicon over the first layer, and a third layer containing nitrogen and silicon over the second layer. Further, it is preferable that the first insulating layer include a fourth layer between the first conductive layer and the first layer and a fifth layer over the third layer, the fourth layer include a region in which a hydrogen content is higher than that in the first layer, and the fifth layer include a region in which the hydrogen content is higher than that in the third layer. Further, it is preferable that the semiconductor device of each of the above structures include a third insulating layer over the first conductive layer, the first insulating layer include a fourth layer over the third layer, the third insulating layer include a region in which the hydrogen content is higher than that in the first layer, and the fourth layer include a region in which the hydrogen content is higher than that in the third layer.

[0023] Further, one embodiment of the present application is a method for manufacturing a semiconductor device, including the steps of: forming a first conductive layer over a substrate; forming an insulating film over the first conductive layer; forming a conductive film over the insulating film; forming a first insulating layer having a first opening portion reaching the first conductive layer and a second conductive layer having a second opening portion overlapping with the first opening portion by processing the insulating film and the conductive film; forming a metal oxide layer over the first conductive layer, the second conductive layer, and the first insulating layer; forming a second insulating layer over the metal oxide layer; supplying a first element to the metal oxide layer through the second insulating layer; and forming a third conductive layer over the second insulating layer, in which the first element is boron or phosphorus.

[0024] In the step of supplying the first element, plasma ion doping or ion implantation is preferably used.

[0025] In the step of supplying the first element, mass separation is preferably not performed.

[0026] Hydrogen is preferably supplied together with the first element.

[0027] The first element is preferably supplied from a direction perpendicular or substantially perpendicular to a top surface of the substrate.

[0028] Effects of Invention

[0029] According to one embodiment of the present application, a micro transistor can be provided. According to one embodiment of the present application, a transistor with a small channel length can be provided. According to one embodiment of the present application, a transistor with a large on-state current can be provided. According to one embodiment of the present application, a transistor with good electric characteristics can be provided. According to one embodiment of the present application, a semiconductor device with a small area occupation can be provided. According to one embodiment of the present application, a semiconductor device with low wiring resistance can be provided. According to one embodiment of the present application, a semiconductor device or a display device with low power consumption can be provided. According to one embodiment of the present application, a transistor, a semiconductor device, or a display device with high reliability can be provided. According to one embodiment of the present application, a display device which is easily high-definition can be provided. According to one embodiment of the present application, a method for manufacturing a semiconductor device or a display device with high productivity can be provided. According to one embodiment of the present application, a novel transistor, a semiconductor device, a display device, and a method for manufacturing the same can be provided.

[0030] Note that the description of these effects does not preclude the presence of other effects. One embodiment of the present application does not necessarily achieve all the effects described above. Other effects inherent to the present application will be apparent from accounts of the present specification, the attached drawings, the claims as well as embodiments to be described. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1Ais a top view showing one example of a semiconductor device. Figure 1B and Figure 1C is a cross-sectional view showing one example of a semiconductor device.

[0032] Figure 2 is a perspective view showing one example of a semiconductor device.

[0033] Figure 3A is a top view showing one example of a semiconductor device. Figure 3B is a cross-sectional view showing one example of a semiconductor device.

[0034] Figure 4A and Figure 4B is a cross-sectional view showing one example of a semiconductor device.

[0035] Figure 5A and Figure 5B is a cross-sectional view showing one example of a semiconductor device.

[0036] Figures 6A to 6C is a cross-sectional view showing one example of a semiconductor device.

[0037] Figures 7A to 7C is a cross-sectional view showing one example of a semiconductor device.

[0038] Figure 8A is a top view showing one example of a semiconductor device. Figure 8B and Figure 8C is a cross-sectional view showing one example of a semiconductor device.

[0039] Figure 9A is a top view showing one example of a semiconductor device. Figure 9B and Figure 9C is a cross-sectional view showing one example of a semiconductor device.

[0040] Figure 10A and Figure 10B is a cross-sectional view showing one example of a semiconductor device.

[0041] Figures 11A to 11D is a cross-sectional view showing one example of a method for manufacturing a semiconductor device.

[0042] Figures 12A to 12C is a cross-sectional view showing one example of a method for manufacturing a semiconductor device.

[0043] Figure 13A and Figure 13B is a cross-sectional view showing one example of a method for manufacturing a semiconductor device.

[0044] Figure 14A and Figure 14Bis a cross-sectional view showing one example of a manufacturing method of a semiconductor device.

[0045] Figures 15A to 15I is a circuit diagram showing one example of a semiconductor device.

[0046] Figure 16A is a top view showing one example of a semiconductor device. Figure 16B is a cross-sectional view showing one example of a semiconductor device.

[0047] Figure 17A is a top view showing one example of a semiconductor device. Figure 17B is a cross-sectional view showing one example of a semiconductor device.

[0048] Figure 18A is a top view showing one example of a semiconductor device. Figure 18B is a cross-sectional view showing one example of a semiconductor device.

[0049] Figure 19A is a top view showing one example of a semiconductor device. Figure 19B is a cross-sectional view showing one example of a semiconductor device.

[0050] Figure 20 is a perspective view showing one example of a display device.

[0051] Figure 21A and Figure 21B is a cross-sectional view showing one example of a display device.

[0052] Figure 22 is a cross-sectional view showing one example of a display device.

[0053] Figures 23A to 23C is a cross-sectional view showing one example of a display device.

[0054] Figure 24A and Figure 24B is a cross-sectional view showing one example of a display device.

[0055] Figure 25 is a cross-sectional view showing one example of a display device.

[0056] Figures 26A to 26F is a diagram showing one example of an electronic device.

[0057] Figures 27A to 27G is a diagram showing one example of an electronic device.

[0058] Figures 28A to 28H is a diagram showing one example of an electronic device.

[0059] Figures 29A to 29Eis a cross-sectional view illustrating a manufacturing method of the sample of Embodiment 1.

[0060] Figure 30A is a graph showing the sheet resistance of the sample of Embodiment 1. Figure 30B is a graph showing the contact resistance of the sample of Embodiment 1.

[0061] Figure 31A is a graph showing the sheet resistance of the sample of Embodiment 1. Figure 31B is a graph showing the contact resistance of the sample of Embodiment 1.

[0062] Figure 32A is a graph showing the sheet resistance of the sample of Embodiment 1. Figure 32B is a graph showing the contact resistance of the sample of Embodiment 1.

[0063] Figure 33A and Figure 33B is a graph showing the Id-Vg characteristics of the transistor of Embodiment 2.

[0064] Figure 34 is a graph showing the on-state current of the transistor of Embodiment 2. DETAILED DESCRIPTION

[0065] Embodiments are described in detail with reference to the accompanying drawings. Note that the present application is not limited to the following description, and it is easily possible for a person skilled in the art to understand that the present application can be changed in various ways without departing from the spirit and scope of the present application. Therefore, the present application should not be interpreted as being limited only to the content described in the following embodiments.

[0066] Note that, in the drawings used in the following description of the present application, the same portions or portions having the same function are denoted by the same reference numerals, and repeated explanation is omitted. Further, the same hatching pattern is sometimes used when portions having the same function are represented, and a symbol is not particularly added.

[0067] Further, in order to facilitate understanding, the position, size, and range, and the like of each component shown in the drawings are not necessarily shown to scale. Therefore, the disclosed application is not necessarily limited to the position, size, and range, and the like disclosed in the drawings.

[0068] Note that, in this specification and the like, the ordinal numbers such as first, second, and the like are added to the components for convenience in order to avoid confusion among the components. The positions, sizes, shapes, and the like of the components shown in the drawings, and the like do not limit the positions, sizes, shapes, and the like of the components. Therefore, the disclosed application is not necessarily limited to shapes shown in the drawings and the like. Note that, in this specification and the like, the ordinal numbers such as first, second, and the like are added to the components for convenience in order to avoid confusion among the components. The positions, sizes, shapes, and the like of the components shown in the drawings, and the like do not limit the positions, sizes, shapes, and the like of the components. Therefore, the disclosed application is not necessarily limited to shapes shown in the drawings and the like.

[0069] In addition, depending on the case or state, "film" and "layer" can be interchanged. For example, "conductive layer" can be changed to "conductive film". Furthermore, "insulating film" can be changed to "insulating layer".

[0070] A transistor is one of semiconductor elements, and functions such as amplification of current or voltage, switching operation of on or off, and the like can be implemented. The transistor in this specification includes an IGFET (Insulated Gate Field Effect Transistor) and a thin film transistor (TFT).

[0071] In this specification and the like, a transistor including an oxide semiconductor or a metal oxide in a channel formation region is referred to as an OS transistor. Further, a transistor including silicon in a channel formation region is referred to as a Si transistor.

[0072] In this specification and the like, a transistor refers to an element including at least three terminals of a gate, a drain, and a source. A transistor has a region where a channel is formed between a drain (a drain terminal, a drain region, or a drain electrode) and a source (a source terminal, a source region, or a source electrode), and current can flow between the source and the drain through the channel formation region. Note that in this specification and the like, the channel formation region refers to a region where current flows.

[0073] In addition, in the case of using transistors having different polarities or in the case where the direction of current flowing in a circuit is changed, the functions of the "source" and the "drain" are sometimes interchanged. Thus, in this specification, the "source" and the "drain" can be interchanged with each other.

[0074] Note that an impurity of a semiconductor refers to, for example, an element other than the main components of a semiconductor. For example, an element having a concentration lower than 0.1 atomic% can be regarded as an impurity. In the case where an impurity is contained, for example, an increase in the defect state density of a semiconductor or a decrease in crystallinity, or the like is sometimes caused. Furthermore, for example, the inclusion of an impurity causes formation of an oxygen vacancy (also referred to as V O ) in an oxide semiconductor. Note that specific examples of impurities can be referred to the description of the later embodiments.

[0075] Note that in this specification and the like, an oxynitride refers to a material whose composition includes more oxygen than nitrogen. An oxynitride refers to a material whose composition includes more nitrogen than oxygen.

[0076] For example, the content of elements such as hydrogen, oxygen, and nitrogen can be analyzed by secondary ion mass spectrometry (SIMS) or X-ray photoelectron spectroscopy (XPS). XPS is suitable when the content of the target element is high (for example, 0.5 atomic% or more or 1 atomic% or more). On the other hand, SIMS is suitable when the content of the target element is low (for example, 0.5 atomic% or less or 1 atomic% or less). In comparing the content of elements, it is more preferable to perform composite analysis using both SIMS and XPS analysis techniques.

[0077] In this specification and the like, "parallel" indicates a state where an angle formed between two straight lines is -10 degrees or more and 10 degrees or less. Thus, a state where the angle is -5 degrees or more and 5 degrees or less is also included. "Substantially parallel" indicates a state where an angle formed between two straight lines is -30 degrees or more and 30 degrees or less. Further, "perpendicular" indicates a state where an angle formed between two straight lines is 80 degrees or more and 100 degrees or less. Thus, a state where the angle is 85 degrees or more and 95 degrees or less is also included. "Substantially perpendicular" indicates a state where an angle formed between two straight lines is 60 degrees or more and 120 degrees or less.

[0078] In this specification and the like, "electrically connected" includes the case where elements "having some kind of electric action" are connected. Here, the elements "having some kind of electric action" are not particularly limited as long as they can receive and transmit an electric signal between connection objects. For example, the elements "having some kind of electric action" include, in addition to an electrode or a wiring, a switching element such as a transistor, a resistive element, a coil, and other elements having a variety of functions.

[0079] In this specification and the like, in the case where not particularly stated otherwise, an off-state current refers to a leakage current between a source and a drain when a transistor is in an off state (also referred to as a non-conducting state, a blocking state). In the case where not particularly stated otherwise, in an n-channel transistor, the off state refers to a state where a voltage V gs is lower than a threshold voltage V th (p-channel transistor V gs is higher than V th ).

[0080] In this specification and the like, always on refers to a state where a channel exists and a current flows through a transistor even when no voltage is applied to a gate. Further, always off refers to a state where no current flows through a transistor when no potential is applied to a gate or a ground potential is supplied to the gate.

[0081] In this specification and the like, the top surface shape of a component refers to the outline shape of the component when viewed from a planar surface. Furthermore, viewed from a planar surface refers to a case where the component is viewed from the direction of the normal line of the surface of a support (e.g., a substrate) on which the component is formed or a surface of the component itself.

[0082] In this specification and the like, "the top surface shapes are substantially uniform" means that at least a part of the outlines of each of the layers in the stack is overlapped. For example, a case where the upper layer and the lower layer are processed by the same mask pattern or a part of the same mask pattern is included. However, in actuality, there is a case where the outlines are not overlapped, and in some cases, the upper layer is positioned inside the lower layer or the upper layer is positioned outside the lower layer, which can also be said to be "the top surface shapes are substantially uniform". When the top surface shapes are uniform or substantially uniform, it can also be said that the end portions are aligned or substantially aligned, or the side end portions are aligned or substantially aligned.

[0083] In this specification and the like, a tapered shape refers to a shape in which at least a part of the side surface of a component is provided obliquely with respect to the substrate surface or the formed surface. For example, a region in which the angle (also referred to as a taper angle) formed by the oblique side surface and the substrate surface or the formed surface is greater than 0 degrees and less than 90 degrees is preferably included. Here, the side surface of the component, the substrate surface, and the formed surface do not necessarily have to be completely flat, and can be an approximately planar shape with a slight curvature or an approximately planar shape with slight unevenness.

[0084] In this specification and the like, in the case where there is a description of "A is in contact with B", at least a part of A is in contact with B. Thus, for example, it can be said that A includes a region in contact with B.

[0085] In this specification and the like, in the case where there is a description of "A is on B", at least a part of A is on B. Thus, for example, it can be said that A includes a region on B.

[0086] In this specification and the like, in the case where there is a description of "A covers B", at least a part of A covers B. Thus, for example, it can be said that A includes a region covering B.

[0087] In this specification and the like, in the case where there is a description of "A overlaps with B", at least a part of A overlaps with B. Thus, for example, it can be said that A includes a region overlapping with B.

[0088] In this specification and the like, a device manufactured using a metal mask or an FMM (Fine Metal Mask) is sometimes referred to as a device having an MM (Metal Mask) structure. Furthermore, in this specification and the like, a device manufactured without using a metal mask or an FMM is sometimes referred to as a device having an MML (Metal Mask Less) structure.

[0089] In this specification and the like, a structure in which light-emitting layers are separately formed in light-emitting elements (also referred to as light-emitting devices) in which emission wavelengths are different is referred to as an SBS (Side By Side) structure. The SBS structure is advantageous in that each light-emitting element can be optimized in terms of materials and a structure, and freedom in selection of materials and a structure is improved, so that improvement in luminance and reliability can be easily achieved.

[0090] In this specification and the like, a hole or an electron is sometimes referred to as a carrier. Specifically, a hole-injection layer or an electron-injection layer is sometimes referred to as a carrier-injection layer, a hole-transport layer or an electron-transport layer is sometimes referred to as a carrier-transport layer, and a hole-blocking layer or an electron-blocking layer is sometimes referred to as a carrier-blocking layer. Note that the above-described carrier-injection layer, carrier-transport layer, and carrier-blocking layer are not always clearly distinguishable. In addition, one layer sometimes has the functions of two or all of a carrier-injection layer, a carrier-transport layer, and a carrier-blocking layer.

[0091] In this specification and the like, a light-emitting element includes an EL layer between a pair of electrodes. The EL layer includes at least a light-emitting layer. Here, as a layer included in the EL layer (also referred to as a functional layer), a light-emitting layer, a carrier-injection layer (a hole-injection layer and an electron-injection layer), a carrier-transport layer (a hole-transport layer and an electron-transport layer), and a carrier-blocking layer (a hole-blocking layer and an electron-blocking layer) can be given. In this specification and the like, a light-receiving element (also referred to as a light-receiving device) includes at least an active layer serving as a photoelectric conversion layer between a pair of electrodes. In this specification and the like, one of a pair of electrodes is referred to as a pixel electrode, and the other is referred to as a common electrode.

[0092] In this specification and the like, a sacrificial layer (also referred to as a mask layer) is at least positioned over a light-emitting layer (more specifically, a layer included in an EL layer and processed into an island shape) and has a function of protecting the light-emitting layer in a manufacturing process.

[0093] In this specification and the like, separation refers to a phenomenon in which a layer, a film, or an electrode is separated due to the shape of a formed surface (e.g., a step or the like).

[0094] (Embodiment 1)

[0095] In this embodiment, a semiconductor device of one embodiment of the present application will be described with reference to FIGS. 1 to 10.

[0096] A semiconductor device of one embodiment of the present application includes a semiconductor layer, a first conductive layer, a second conductive layer, a third conductive layer, a first insulating layer, and a second insulating layer.

[0097] The first conductive layer is used as one of a source electrode and a drain electrode of the transistor, the second conductive layer is used as the other of the source electrode and the drain electrode of the transistor, the third conductive layer is used as a gate electrode of the transistor, and the second insulating layer is used as a gate insulating layer of the transistor.

[0098] The first insulating layer is provided over the first conductive layer, and the second conductive layer is provided over the first insulating layer. The semiconductor layer is in contact with a top surface of the first conductive layer, a top surface and side surfaces of the second conductive layer, and side surfaces of the first insulating layer. The second insulating layer is provided over the semiconductor layer. The third conductive layer is provided over the second insulating layer and overlaps with the semiconductor layer with the second insulating layer interposed therebetween.

[0099] The semiconductor layer includes a first region in contact with a top surface of the first conductive layer and a second region in contact with a top surface of the second conductive layer. One of the first region and the second region is used as a source region, and the other is used as a drain region.

[0100] The first region and the second region contain an impurity element. As the impurity element, a first element is preferably used. Alternatively, as the impurity element, both the first element and hydrogen are preferably used.

[0101] As the first element, one or more of boron, aluminum, indium, carbon, silicon, germanium, tin, phosphorus, arsenic, antimony, magnesium, calcium, titanium, copper, zinc, tungsten, molybdenum, tantalum, hafnium, cerium, and a rare gas (helium, neon, argon, krypton, xenon, and the like) is preferably used.

[0102] The first element is not limited to the above elements, and one or more of elements included in a first transition element (3d transition element, 3d transition metal), a second transition element (4d transition element, 4d transition metal), a third transition element (5d transition element, 5d transition metal), an alkaline earth metal element, and a rare earth element can be used.

[0103] By supplying (or adding or implanting) the first element to the first region and the second region, the first element extracts oxygen in the regions, and oxygen vacancies are generated in the regions. Further, the oxygen vacancies are bonded to hydrogen in the film to generate carriers, and thus the first region and the second region can be made low in resistance. Thus, the sheet resistance of the semiconductor layer, the contact resistance between the semiconductor layer and the source electrode, and the contact resistance between the semiconductor layer and the drain electrode can be reduced. Thus, the on-state current of the transistor can be increased. By increasing the on-state current, the operating voltage of the transistor can be reduced. Thus, the power consumption of the semiconductor device can be reduced.

[0104] In the case where an element that easily bonds with oxygen is used as the first element, the first element exists in a state of bonding with oxygen in the semiconductor layer. Further, when an element that is stabilized by bonding with oxygen is used as the first element, the first element in the semiconductor layer stably exists in a state of being oxidized, and thus is not easily removed by heating or the like in a manufacturing process of the semiconductor device, and thus a low-resistance region that is stable in a state of low resistance can be realized. Thus, as the first element, an element that exists as a solid in a state of oxide in a standard state is preferably used. Specifically, as the preferred first element, a typical nonmetallic element other than hydrogen, a typical metallic element, and a transition element (transition metal) can be given, and as the particularly preferred first element, boron, phosphorus, magnesium, aluminum, and silicon can be given.

[0105] Thus, boron, phosphorus, magnesium, aluminum, or silicon is preferably used as one of the first elements. Further, boron or phosphorus is particularly preferably used as one of the first elements.

[0106] Further, in addition to the above-described function of generating an oxygen vacancy, hydrogen has a function of bonding with an oxygen vacancy, and thus is suitable for use as an impurity element.

[0107] By using both the first element and hydrogen as the impurity element, the resistance of the source region and the drain region in the semiconductor layer can be easily reduced, and a state of low resistance can be stably maintained.

[0108] The first insulating layer can also have a first opening portion reaching the first conductive layer. In addition, the second conductive layer can have a second opening portion overlapping with the first opening portion. At this time, the third conductive layer preferably overlaps with the semiconductor layer with the second insulating layer interposed at a position overlapping with the first opening portion and the second opening portion. In addition, a groove (slit) can be provided instead of the first opening portion and the second opening portion.

[0109] In the transistor of one embodiment of the present application, the source electrode and the drain electrode are different in height at the positions thereof, and current flowing through the semiconductor layer flows in the height direction. That is, it can be said that the channel length direction has a component of the height direction (vertical direction), and thus the transistor of one embodiment of the present application can be referred to as a VFET (Vertical Field Effect Transistor), a vertical transistor, a vertical channel transistor, a vertical channel type transistor, or the like.

[0110] Since the source electrode, the semiconductor layer, and the drain electrode can be provided in a stacked manner, the transistor of one embodiment of the present application can have a much smaller area than a so-called planar transistor in which the semiconductor layer is provided in a planar shape.

[0111] [Transistor 100]

[0112] Figure 1A and Figure 3A A top view of the transistor 100 is shown. Figure 3A In contrast to Figure 1A , a diameter D143 of the opening portion 143 and a channel width W100 of the transistor 100 are illustrated, and a dotted line B1-B2 is not illustrated. In Figure 1A and Figure 3A , the insulating layer is not described. Note that the description of part of the components is omitted in other top views as well.

[0113] Figure 1B and Figure 3B are cross-sectional views along a dotted line A1-A2 in Figure 1A and Figure 3A . Figure 3B It can also be said to be an enlarged view of Figure 1B . Figure 1B The opening portion 141 and the opening portion 143 are illustrated, Figure 3B The diameter D143, the channel width W100, a channel length L100 of the transistor 100, a thickness T110 of the insulating layer 110c, an angle Θ110, and an angle Θ112 are illustrated. Details of these components will be described later. Note that Figure 1B and Figure 3B commonly illustrate other components. Figure 1C is a cross-sectional view along a dotted line B1-B2 in Figure 1A .

[0114] Figure 2 A perspective view of the transistor 100 is illustrated. In Figure 2 , the insulating layer is not described.

[0115] The transistor 100 is provided over a substrate 102. The transistor 100 includes a conductive layer 112a, an insulating layer 110 (insulating layers 110b, 110c, and 110d), a semiconductor layer 108, a conductive layer 112b, an insulating layer 106, and a conductive layer 104. Each layer included in the transistor 100 can have a single-layer structure or a stacked-layer structure. Note that the insulating layer 110 can not be included in the components of the transistor 100. That is, the semiconductor device of one embodiment of the present application includes the transistor 100 and the insulating layer 110.

[0116] The conductive layer 112a is provided over the substrate 102. The conductive layer 112a is used as one of a source electrode and a drain electrode of the transistor 100.

[0117] The insulating layer 110 is positioned over the substrate 102 and the conductive layer 112a. The insulating layer 110 is in contact with the conductive layer 112a. The insulating layer 110 includes an opening portion 141 reaching the conductive layer 112a.

[0118] The insulating layer 110 has a stacked structure of the insulating layer 110b over the substrate 102 and the conductive layer 112a, the insulating layer 110c over the insulating layer 110b, and the insulating layer 110d over the insulating layer 110c.

[0119] The conductive layer 112b is provided over the insulating layer 110. An opening portion 143 overlapping with the opening portion 141 is provided in the conductive layer 112b. The conductive layer 112b is used as the other of the source and drain electrodes of the transistor. The conductive layer 112b is preferably not provided in the inside of the opening portion 141. That is, the conductive layer 112b preferably does not include a region in contact with a side surface of the opening portion 141 of the insulating layer 110.

[0120] The semiconductor layer 108 is in contact with a top surface of the conductive layer 112a, a side surface of the insulating layer 110, and a top surface and a side surface of the conductive layer 112b. The semiconductor layer 108 is provided in contact with an end portion on the side of the opening portion 141 in the insulating layer 110 (which can be referred to as a side wall of the opening portion 141) and an end portion on the side of the opening portion 143 in the conductive layer 112b (which can be referred to as a side wall of the opening portion 143). The semiconductor layer 108 is in contact with the conductive layer 112a through the opening portion 141 and the opening portion 143.

[0121] A part of the semiconductor layer 108 includes a low-resistance region 108n. The low-resistance region 108n contains an impurity element. The low-resistance region 108n is a region with higher concentration of the impurity element and lower resistance than other regions (a channel formation region or the like) of the semiconductor layer 108.

[0122] In the semiconductor layer 108, the low-resistance region 108n in contact with the conductive layer 112a is used as one of the source region and the drain region, and the low-resistance region 108n in contact with the conductive layer 112b is used as the other of the source region and the drain region. The semiconductor layer 108 includes a region serving as a channel formation region between the source region and the drain region.

[0123] Figures 1A to 1C An example is shown in which the low-resistance region 108n is formed in a region between the top surface of the conductive layer 112a and the bottom surface of the conductive layer 104 in a region of the semiconductor layer 108 in contact with the top surface of the conductive layer 112a. The region in which the low-resistance region 108n is formed is not limited thereto, and for example, the entire region in contact with the top surface of the conductive layer 112a can also be formed with the low-resistance region 108n. For example, the impurity element sometimes diffuses in a direction parallel to the top surface of the substrate 102 when the impurity element is supplied, or diffuses in the direction by heat applied in a process after the impurity element is supplied.

[0124] In addition, Figures 1A to 1CThe following example is shown: a low-resistance region 108n is formed in a region of the semiconductor layer 108 that is in contact with the top surface of the conductive layer 112b. Note that a low-resistance region 108n can also be provided in a region of the semiconductor layer 108 that is in contact with the side surface of the conductive layer 112b. Further, a low-resistance region 108n can also be provided in part of a region of the semiconductor layer 108 that is in contact with the side surface of the insulating layer 110.

[0125] As the impurity element, it is preferable to use the first element. Alternatively, as the impurity element, it is preferable to use both the first element and hydrogen.

[0126] As the first element, one or more of boron, aluminum, indium, carbon, silicon, germanium, tin, phosphorus, arsenic, antimony, magnesium, calcium, titanium, copper, zinc, tungsten, molybdenum, tantalum, hafnium, cerium, and a rare gas (helium, neon, argon, krypton, xenon, and the like) is preferably used.

[0127] The first element is not limited to the above elements, and one or more of elements included in a first transition element (3d transition element, 3d transition metal), a second transition element (4d transition element, 4d transition metal), a third transition element (5d transition element, 5d transition metal), an alkaline earth metal element, and a rare earth element can be used.

[0128] By supplying (or adding or implanting) the first element to the source region and the drain region, the first element captures oxygen in the source region and the drain region, and oxygen vacancies are generated in the source region and the drain region. Further, the oxygen vacancies bond with hydrogen in the semiconductor layer 108 to generate carriers, and thus the source region and the drain region can be made low resistance. Thus, the sheet resistance of the semiconductor layer 108, the contact resistance between the semiconductor layer 108 and the conductive layer 112a, and the contact resistance between the semiconductor layer 108 and the conductive layer 112b can be reduced. Thus, the on-state current of the transistor 100 can be increased. By increasing the on-state current, the operating voltage of the transistor 100 can be reduced. Thus, the power consumption of the semiconductor device can be reduced.

[0129] In the case where an element that easily bonds with oxygen is used as the first element, the first element exists in a state of bonding with oxygen in the semiconductor layer 108. Further, when an element that is stabilized by bonding with oxygen is used as the first element, the first element in the semiconductor layer 108 stably exists in a state of being oxidized, and thus is not easily removed by heating or the like in the manufacturing process of the transistor 100, and thus a low-resistance region that is stable in a low-resistance state can be realized. Thus, as the first element, an element that exists as a solid in the case where the oxide is in a standard state is preferably used. Specifically, as the preferable first element, a typical non-metallic element other than hydrogen, a typical metallic element, and a transition element (transition metal) can be given, and as the particularly preferable first element, boron, phosphorus, magnesium, aluminum, and silicon can be given.

[0130] Thus, boron, phosphorus, magnesium, aluminum, or silicon is preferably used as one of the first elements. Further, boron or phosphorus is particularly preferably used as one of the first elements.

[0131] Further, in addition to the function of generating oxygen vacancies described above, hydrogen has a function of bonding to oxygen vacancies, and thus is suitable for use as an impurity element.

[0132] By using both the first element and hydrogen as impurity elements, the resistance of the low-resistance region 108n can be easily reduced, and a state of low resistance can be stably maintained.

[0133] Further, when both the first element and hydrogen are supplied, ions generated from source gas can be added without mass separation, and thus productivity can be improved, and thus is preferable. For example, by using B2H6 gas, boron and hydrogen can be supplied as impurity elements. Further, for example, by using PH3 gas, phosphorus and hydrogen can be supplied as impurity elements. Further, the method of supplying impurity elements is not limited thereto. For example, ions generated from source gas can be subjected to mass separation to add specific elements. For example, B2H6 gas can be used, and boron can be added to the low-resistance region 108n after mass separation.

[0134] The low-resistance region 108n preferably includes the impurity elements at a concentration of 1 x 10 19 atoms / cm 3 The above and 1 x 10 23 atoms / cm 3 The following, preferably 5 x 10 19 atoms / cm 3 The above and 5 x 10 22 atoms / cm 3 The following, more preferably 1 x 10 20 atoms / cm 3 The above and 1 x 10 22 atoms / cm 3 The following region. In the case where a plurality of impurity elements are included, the concentration of each impurity element is preferably within the above range.

[0135] Note that, sometimes, the channel formation region in the semiconductor layer 108 is also supplied with impurity elements. Alternatively, sometimes, a part of the impurity elements included in the low-resistance region 108n diffuses to the channel formation region due to the influence of heat applied in a manufacturing process, or the like. The concentration of impurity elements in the channel formation region is preferably one-tenth or less, more preferably one-hundredth or less, of the concentration of impurity elements in the low-resistance region 108n.

[0136] The concentration of impurity elements contained in the semiconductor layer 108 (including the low-resistance region 108n) and the insulating layer 106 can be analyzed, for example, by a secondary ion mass spectrometry (SIMS) or an X-ray photoelectron spectroscopy (XPS). In the case of XPS analysis, the concentration distribution in the depth direction can be obtained by combining XPS analysis and ion sputtering from the surface side or the back surface side.

[0137] In the production of the semiconductor device of one embodiment of the present application, the source region and the drain region of the semiconductor layer 108 are preferably more easily added with impurity elements than the channel formation region. Thus, impurity elements are preferably added from a direction perpendicular or substantially perpendicular to the top surface of the substrate 102. At this time, in the semiconductor layer 108, the amount of addition of impurity elements is less in a plane inclined to the top surface of the substrate 102 than in a plane parallel or substantially parallel to the top surface of the substrate 102. In other words, the amount of addition of impurity elements is more in the source region and the drain region of the semiconductor layer 108 than in the channel formation region. Thus, the source region and the drain region can be preferentially made low in resistance.

[0138] Further, in the production of the semiconductor device of one embodiment of the present application, it is preferable that the insulating layer 106 add impurity elements to the semiconductor layer 108. At this time, the thickness of the insulating layer 106 in the direction in which impurity elements are added is greater in a region provided along the side surface of the insulating layer 110 than in a region provided along the top surface of the conductive layer 112a or the top surface of the conductive layer 112b. As one example, the thickness T2 is greater than the thickness T1 shown in FIG. 1. Figure 3B In this case, the thickness T1 is one example of the thickness of the insulating layer 106 in the direction in which impurity elements are added in a region provided along the top surface of the conductive layer 112a. The thickness T2 is one example of the thickness of the insulating layer 106 in the direction in which impurity elements are added in a region provided along the side surface of the insulating layer 110. Thus, the amount of addition of impurity elements is more in a region of the semiconductor layer 108 provided along the top surface of the conductive layer 112a or the top surface of the conductive layer 112b than in a region provided along the side surface of the insulating layer 110. Thus, the entry of impurity elements into the channel formation region of the semiconductor layer 108 can be suppressed, and the source region and the drain region can be preferentially made low in resistance.

[0139] Here, the thickness of the insulating layer 106 (thickness in a direction perpendicular or substantially perpendicular to the surface to be formed, such as thickness Tl) is preferably 1 nm or more and 200 nm or less, more preferably 1 nm or more and 150 nm or less, and further preferably 1 nm or more and 100 nm or less. For example, in the case where the channel length is 100 nm or more and 500 nm or less, the thickness of the insulating layer 106 is preferably 30 nm or more and 100 nm or less. In addition, for example, in the case where the channel length is 10 nm or more and 100 nm or less, the thickness of the insulating layer 106 is preferably 1 nm or more and 50 nm or less. In addition, for example, in the case where the channel length is 1 nm or more and 10 nm or less, the thickness of the insulating layer 106 is preferably 1 nm or more and 10 nm or less.

[0140] The greater the thickness of the insulating layer 106, the greater the difference between the thickness Tl and the thickness T2 can be. Thus, the entry of impurity elements into the channel formation region of the semiconductor layer 108 can be suppressed, and thus the source region and the drain region can be preferentially low-resistance. On the other hand, in order to miniaturize the transistor or manufacture a transistor having an extremely small channel length, the thickness Tl is preferably small from the viewpoints of improvement of on-state current, suppression of short channel effects, and the like.

[0141] In the case where the semiconductor layer 108 is supplied with impurity elements through the insulating layer 106, the insulating layer 106 sometimes contains impurity elements as well. When the low-resistance region 108n includes a portion where the concentration of impurity elements is higher than that of the insulating layer 106, the resistance of the low-resistance region 108n can be further reduced, and thus this is preferable.

[0142] The insulating layer 106 preferably includes an insulating layer containing oxygen. In the case where an element that easily bonds with oxygen is used as an impurity element, as with the semiconductor layer 108, the impurity element exists in a state of bonding with oxygen in the insulating layer 106 as well. Since the oxygen and the impurity element are stabilized by bonding, even if heating is performed, the region containing the impurity element becomes a state where oxygen hardly detaches, that is, a state where oxygen hardly diffuses to other layers. Thus, oxygen can be supplied to the channel formation region while suppressing the supply of oxygen from the insulating layer 106 to the low-resistance region 108n. Therefore, the oxygen vacancy of the channel formation region can be reduced while preventing the increase in resistance of the low-resistance region 108n. As a result, a transistor having good electrical characteristics and high reliability can be implemented.

[0143] For example, in the case where boron is used as an impurity element, the boron contained in the low-resistance region 108n and the insulating layer 106 is likely to exist in a state of bonding with oxygen. This can be confirmed by observing a spectral peak due to B2O3 bonding in XPS analysis. In addition, in XPS analysis, a spectral peak due to a state where boron elements exist alone is not observed or the peak intensity thereof is extremely small to the extent of being buried in the background noise of the detection lower limit.

[0144] Figure 1B An example in which the end portion of the semiconductor layer 108 is in contact with the top surface of the conductive layer 112b is shown, but the present application is not limited thereto. The semiconductor layer 108 can also cover the end portion of the conductive layer 112b, and the end portion of the semiconductor layer 108 can be in contact with the insulating layer 110 (see the transistor 100G described later ( Figure 9B

[0145] The insulating layer 106 is positioned over the insulating layer 110, the semiconductor layer 108, and the conductive layer 112b. The insulating layer 106 is provided along the side wall of the opening portion 141 and the side wall of the opening portion 143 with the semiconductor layer 108 interposed therebetween. The insulating layer 106 is used as a gate insulating layer (which can be referred to as a first gate insulating layer).

[0146] The conductive layer 104 is positioned over the insulating layer 106. The conductive layer 104 overlaps with the semiconductor layer 108 with the insulating layer 106 interposed therebetween in the inside of the opening portion 141 and the opening portion 143. The conductive layer 104 is used as a gate electrode of the transistor (which can be referred to as a first gate electrode).

[0147] The conductive layer 112a, the conductive layer 112b, and the conductive layer 104 can all be used as a wiring, and the transistor 100 can be provided in a region where these wirings overlap with each other. That is, in a circuit including the transistor 100 and a wiring, the area occupied by the transistor 100 and the wiring can be reduced. Accordingly, a semiconductor device can be made small by reducing the area occupied by a circuit.

[0148] For example, in the case where the semiconductor device of one embodiment of the present application is used for a pixel circuit of a display device, the area occupied by the pixel circuit can be reduced, and a high-definition display device can be achieved. Further, for example, in the case where the semiconductor device of one embodiment of the present application is used for a driver circuit (e.g., one or both of a gate line driver circuit and a source line driver circuit) of a display device, the area occupied by the driver circuit can be reduced, and thus a display device with narrow bezels can be achieved.

[0149] Reference is made to Figure 3A and Figure 3B The channel length and the channel width of the transistor 100 are described.

[0150] In Figure 3B the channel length L100 of the transistor 100 is indicated by a double-headed arrow in a dashed line. The channel length L100 can be regarded as the shortest distance between a portion of the semiconductor layer 108 in contact with the insulating layer 110b and a portion in contact with the insulating layer 110d, when viewed in cross section.

[0151] ​The channel length L100 of the transistor 100 corresponds to the length of the side of the opening portion 141 of the insulating layer 110c when seen in cross section. That is, the channel length L100 is determined by the thickness T110 of the insulating layer 110c and the angle θ110 formed by the side of the opening portion 141 of the insulating layer 110c and the surface of the insulating layer 110c (in this case, the top surface of the insulating layer 110b) on which the surface is formed. Thus, the channel length L100 can be set to a value smaller than the resolution limit of an exposure device, for example, and a micro transistor can be realized. Specifically, a transistor with an extremely small channel length that cannot be realized with an exposure device used in mass production of conventional flat panel displays (e.g., with a minimum line width of 2 μm or 1.5 μm or the like) can be realized. Further, a transistor with a channel length of less than 10 nm can be realized without using an extremely expensive exposure device using the most advanced LSI technology.

[0152] The channel length L100 can be, for example, 5 nm or more, 7 nm or more, or 10 nm or more and less than 3 μm, 2.5 μm or less, 2 μm or less, 1.5 μm or less, 1.2 μm or less, 1 μm or less, 500 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, 50 nm or less, 30 nm or less, or 20 nm or less. For example, the channel length L100 is preferably 10 nm or more and 1 μm or less, more preferably 10 nm or more and 500 nm or less, further preferably 10 nm or more and 100 nm or less, and still further preferably 10 nm or more and 50 nm or less.

[0153] By reducing the channel length L100, the on-state current of the transistor 100 can be increased. By using the transistor 100, a circuit that operates at high speed can be manufactured. Furthermore, the area occupied by the circuit can be reduced. Thus, a small semiconductor device can be realized. For example, in the case where the semiconductor device of one embodiment of the present application is used for a large display device or a high-definition display device, signal delay of each wiring can be reduced even when the number of wirings is increased, which can suppress display unevenness. Further, since the area occupied by the circuit can be reduced, the frame of the display device can be reduced.

[0154] The channel length L100 can be controlled by adjusting the thickness T110 and the angle θ110 of the insulating layer 110c. Note that the thickness T110 of the insulating layer 110c is indicated by a dotted line double-headed arrow in Figure 3B

[0155] ​The thickness T110 of the insulating layer 110c can be, for example, 10 nm or more, 50 nm or more, 100 nm or more, 150 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, or 500 nm or more and less than 3.0 μm, 2.5 μm or less, 2.0 μm or less, 1.5 μm or less, 1.2 μm or less, or 1.0 μm or less. In the case of manufacturing a transistor in which the channel length L100 is small, the thickness T110 of the insulating layer 110c can be, for example, 5 nm or more, 7 nm or more, or 10 nm or more and 1 μm or less, 500 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, 50 nm or less, 30 nm or less, or 20 nm or less.

[0156] Here, in the manufacturing of the semiconductor device of one embodiment of the present application, it is preferable that the source region and the drain region of the semiconductor layer 108 be easily doped with an impurity element as compared to the channel formation region. The greater the thickness T110 of the insulating layer 110c, the greater the difference between the thickness T1 and the thickness T2 can be. Thus, entry of the impurity element into the channel formation region can be suppressed, and the source region and the drain region of the semiconductor layer 108 can be preferentially low-resistance-doped. On the other hand, in order to miniaturize a transistor or manufacture a transistor in which the channel length is extremely small, the thickness T110 is preferably small. For example, the thickness T110 of the insulating layer 110c is preferably 10 nm or more and 1 μm or less, more preferably 10 nm or more and 500 nm or less, still more preferably 10 nm or more and 300 nm or less, even more preferably 10 nm or more and 100 nm or less, and still even more preferably 10 nm or more and 50 nm or less.

[0157] The side surface of the opening portion 141 of the insulating layer 110c is preferably a vertical shape or a tapered shape. The angle θ110 of the side surface of the opening portion 141 of the insulating layer 110c with respect to the surface of the insulating layer 110c (here, the top surface of the insulating layer 110b) is preferably 90 degrees or less. By reducing the angle θ110, the coverage of a layer provided over the insulating layer 110c (e.g., the semiconductor layer 108) can be improved. Further, the smaller the angle θ110, the greater the channel length L100 can be, and the greater the angle θ110, the smaller the channel length L100 can be. Figure 1B 、 Figure 1C and Figure 3B An example in which the side surface of the opening portion 141 of the insulating layer 110c is a tapered shape (the angle θ110 is less than 90 degrees) is shown. Figure 4A An example in which the side surface of the opening portion 141 of the insulating layer 110c is a vertical shape (the angle θ110 is 90 degrees) is shown.

[0158] Further, Figure 3BAn example is shown where the angle θ110 and the angle θ112 formed by the side surface of the opening 143 of the conductive layer 112b and the surface on which the conductive layer 112b is formed (in this case, the top surface of the insulating layer 110) are equal. On the other hand, Figure 4B Examples are shown where angles θ110 and θ112 are different from each other.

[0159] like Figure 4B As shown, when viewed in cross-section, angle θ112 is preferably smaller than angle θ110. By making angle θ112 smaller than angle θ110, the step of the formed surface of the layer (e.g., semiconductor layer 108) on the conductive layer 112b and the insulating layer 110 is reduced, thereby improving the coverage of the layer. As a result, problems such as breaks or voids in the layer can be suppressed.

[0160] For example, by using different methods to form openings 141 and 143, angles θ110 and θ112 can be different. For example, by using wet etching when forming opening 143 and dry etching when forming opening 141, angle θ112 can be smaller than angle θ110.

[0161] Angles θ110 and θ112 can be, for example, greater than 30 degrees, greater than 35 degrees, greater than 40 degrees, greater than 45 degrees, greater than 50 degrees, greater than 55 degrees, greater than 60 degrees, greater than 65 degrees, greater than 70 degrees, or greater than 75 degrees and less than 90 degrees, less than 85 degrees, or less than 80 degrees. Additionally, angles θ110 and θ112 can also be less than 75 degrees, less than 70 degrees, less than 65 degrees, or less than 60 degrees.

[0162] When angles θ110 and θ112 are 80 degrees or more and 90 degrees or less, it is preferable to use a deposition method with high coverage to form the film covering the insulating layer 110. For example, it is preferable to use chemical vapor deposition (CVD) to form the conductive layer 104 and atomic layer deposition (ALD) to form the insulating layer 106 and the semiconductor layer 108. Alternatively, it is preferable to use ALD to form the conductive layer 104, the insulating layer 106, and the semiconductor layer 108, for example. Furthermore, when angles θ110 and θ112 are 60 degrees or more and 85 degrees or less, a deposition method with higher productivity can also be used to form the film covering the insulating layer 110. For example, it is preferable to use sputtering to form the semiconductor layer 108.

[0163] As described above, in the production of the semiconductor device of one embodiment of the present application, it is preferable that the source region and the drain region of the semiconductor layer 108 be more easily doped with impurity elements than the channel formation region. The closer the angle θ 110 and the angle θ 112 are to 90 degrees, the greater the difference between the thickness T1 and the thickness T2 can be. Thus, entry of impurity elements into the channel formation region can be suppressed, and the source region and the drain region of the semiconductor layer 108 can be preferentially made low-resistance. In particular, the angle θ 110 and the angle θ 112 are preferably greater than or equal to 65 degrees and less than or equal to 90 degrees, more preferably greater than or equal to 70 degrees and less than or equal to 90 degrees, and further preferably greater than or equal to 75 degrees and less than or equal to 90 degrees.

[0164] Note that the angle θ 110 is set with reference to the insulating layer 110c here, but can be set with reference to the entire insulating layer 110. That is, the angle θ 110 can also be the angle formed by the side of the opening portion 141 of the insulating layer 110 and the surface of the insulating layer 110 on which the conductive layer 112a is formed (the top surface of the conductive layer 112a here).

[0165] In addition, when the channel formation region includes a region of the semiconductor layer 108 in contact with the insulating layer 110b and a region in contact with the insulating layer 110d, the channel length L100 can be said to be the shortest distance between the portion of the semiconductor layer 108 in contact with the conductive layer 112a and the portion in contact with the conductive layer 112b when viewed in cross section. In addition, the channel length L100 corresponds to the sum of the lengths of the sides of the opening portions 141 of the insulating layers 110b, 110c, and 110d when viewed in cross section.

[0166] In Figure 3A and Figure 3B the diameter D143 of the opening portion 143 is indicated by a double-headed arrow with a double-dot chain line. Figure 3A An example in which the top surface shape of the opening portion 141 and the opening portion 143 is a circular shape with a diameter D143 is illustrated. At this time, the channel width W100 of the transistor 100 coincides with the circumference of the circle. That is, the channel width W100 is π x D143. In this manner, when the top surface shape of the opening portion 141 and the opening portion 143 is a circular shape, a transistor with a smaller channel width than that of a transistor with another shape can be realized.

[0167] Note that the diameter of the opening portion 141 and the diameter of the opening portion 143 are not necessarily the same. In addition, the diameter of the opening portion 141 and the diameter of the opening portion 143 can vary in the depth direction. As the diameter of the opening portion, for example, an average of the diameter of the highest position, the diameter of the lowest position, and the diameter of the position of the middle point of the insulating layer 110 (or the insulating layer 110c) when viewed in cross section can be used. Alternatively, as the diameter of the opening portion, for example, any one of the diameter of the highest position, the diameter of the lowest position, or the diameter of the position of the middle point of the insulating layer 110 (or the insulating layer 110c) when viewed in cross section can be used.

[0168] In the case where the opening portion 143 is formed using photolithography, the diameter D143 of the opening portion 143 is equal to or larger than the resolution limit of an exposure device. The diameter D143 can be, for example, equal to or larger than 20 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, or 500 nm and smaller than 5.0 μm, 4.5 μm, 4.0 μm, 3.5 μm, 3.0 μm, 2.5 μm, 2.0 μm, 1.5 μm, or 1.0 μm.

[0169] The top surface shape of the opening portion 141 and the opening portion 143 is not limited to a specific shape and can be, for example, a circular shape, an elliptical shape, a triangular shape, a quadrangular shape (including a rectangular shape, a rhombic shape, a square shape), a pentagonal shape, a star polygonal shape, or a polygonal shape with rounded corners. The polygonal shape can be a concave polygonal shape (a polygonal shape in which at least one internal angle is greater than 180 degrees) or a convex polygonal shape (a polygonal shape in which all internal angles are equal to or smaller than 180 degrees). As illustrated in FIGS. 1A and 1B, the top surface shape of the opening portion 141 and the opening portion 143 is preferably a circular shape. By making the top surface shape of the opening portion a circular shape, the processing accuracy when forming the opening portion can be improved and a micro opening portion can be formed. Note that in this specification and the like, a circular shape is not limited to a perfect circle. Figure 1A As illustrated in FIGS. 1A and 1B, the top surface shape of the opening portion 141 and the opening portion 143 is preferably a circular shape. By making the top surface shape of the opening portion a circular shape, the processing accuracy when forming the opening portion can be improved and a micro opening portion can be formed. Note that in this specification and the like, a circular shape is not limited to a perfect circle.

[0170] In this specification and the like, the top surface shape of the opening portion 141 refers to the shape of the top surface end portion of the opening portion 141 side of the insulating layer 110. In addition, the top surface shape of the opening portion 143 refers to the shape of the bottom surface end portion of the opening portion 143 side of the conductive layer 112b.

[0171] As illustrated in FIGS. 1A and 1B, the top surface shape of the opening portion 141 and the opening portion 143 is preferably a circular shape. By making the top surface shape of the opening portion a circular shape, the processing accuracy when forming the opening portion can be improved and a micro opening portion can be formed. Note that in this specification and the like, a circular shape is not limited to a perfect circle. Figure 1A As illustrated in FIGS. 1A and 1B, the top surface shape of the opening portion 141 and the opening portion 143 is preferably a circular shape. By making the top surface shape of the opening portion a circular shape, the processing accuracy when forming the opening portion can be improved and a micro opening portion can be formed. Note that in this specification and the like, a circular shape is not limited to a perfect circle. Figure 1B As illustrated in FIGS. 1A and 1B, the top surface shape of the opening portion 141 and the opening portion 143 is preferably a circular shape. By making the top surface shape of the opening portion a circular shape, the processing accuracy when forming the opening portion can be improved and a micro opening portion can be formed. Note that in this specification and the like, a circular shape is not limited to a perfect circle. Figure 1C As illustrated in FIGS. 1A and 1B, the top surface shape of the opening portion 141 and the opening portion 143 is preferably a circular shape. By making the top surface shape of the opening portion a circular shape, the processing accuracy when forming the opening portion can be improved and a micro opening portion can be formed. Note that in this specification and the like, a circular shape is not limited to a perfect circle.

[0172] Note that the top surface shape of the opening portion 141 and the top surface shape of the opening portion 143 can not be the same as each other (see the transistor 100F described later). Figure 8B As illustrated in FIGS. 1A and 1B, the top surface shape of the opening portion 141 and the opening portion 143 is preferably a circular shape. By making the top surface shape of the opening portion a circular shape, the processing accuracy when forming the opening portion can be improved and a micro opening portion can be formed. Note that in this specification and the like, a circular shape is not limited to a perfect circle.

[0173] [Insulating Layer 110]

[0174] The insulating layer 110 can have a single-layer structure or a stacked-layer structure, and preferably has a stacked-layer structure of three or more layers.

[0175] As each layer constituting the insulating layer 110, an inorganic insulating film is preferably used. As the inorganic insulating film, for example, an oxide insulating film, a nitride insulating film, an oxynitride insulating film, and an oxynitride insulating film can be given. As the oxide insulating film, for example, a silicon oxide film, an aluminum oxide film, a magnesium oxide film, a gallium oxide film, a germanium oxide film, a yttrium oxide film, a zirconium oxide film, a lanthanum oxide film, a neodymium oxide film, a hafnium oxide film, a tantalum oxide film, a cerium oxide film, a gallium zinc oxide film, and a hafnium aluminum oxide film can be given. As the nitride insulating film, for example, a silicon nitride film and an aluminum nitride film can be given. As the oxynitride insulating film, for example, a silicon oxynitride film, an aluminum oxynitride film, a gallium oxynitride film, a yttrium oxynitride film, and a hafnium oxynitride film can be given. As the oxynitride insulating film, for example, a silicon oxynitride film and an aluminum oxynitride film can be given.

[0176] The insulating layer 110 includes a portion in contact with the semiconductor layer 108. When an oxide semiconductor is used as the semiconductor layer 108, in order to improve the interface characteristics of the semiconductor layer 108 and the insulating layer 110, it is preferable to use an oxide in at least a part of the portion of the insulating layer 110 in contact with the semiconductor layer 108. Specifically, it is preferable to use an oxide in the portion of the insulating layer 110 in contact with the channel formation region of the semiconductor layer 108. The channel formation region is a high-resistance region in which the carrier concentration is low. It can be said that the channel formation region is i-type (intrinsic) or substantially i-type.

[0177] As the insulating layer 110c in contact with the channel formation region of the semiconductor layer 108, a layer containing oxygen is preferably used. The insulating layer 110c preferably includes a region having a higher oxygen content than one or both of the insulating layer 110b and the insulating layer 110d.

[0178] The insulating layer 110c preferably uses any one or a plurality of the above-described oxide insulating film and oxynitride insulating film. Specifically, the insulating layer 110c preferably uses one or both of a silicon oxide film and a silicon oxynitride film. When the insulating layer 110c is a layer with a high oxygen content, an i-type region is easily formed in a region of the semiconductor layer 108 in contact with the insulating layer 110c and its vicinity.

[0179] The insulating layer 110c is more preferably a film that releases oxygen by heating. Since the insulating layer 110c releases oxygen due to heat applied in the manufacturing process of the transistor 100, oxygen can be supplied to the semiconductor layer 108. By supplying oxygen from the insulating layer 110c to the semiconductor layer 108, particularly to the channel formation region of the semiconductor layer 108, oxygen vacancies in the semiconductor layer 108 can be reduced, and a transistor with good electrical characteristics and high reliability can be implemented.

[0180] For example, oxygen can be supplied to the insulating layer 110c by performing a heat treatment in an oxygen-containing atmosphere or performing a plasma treatment in an oxygen-containing atmosphere. Alternatively, oxygen can be supplied by depositing an oxide film on the top surface of the insulating layer 110c using a sputtering method in an oxygen atmosphere. Then, the oxide film can be removed. In Embodiment 2, an example in which a nitrogen monoxide (N2O) plasma treatment and deposition of a metal oxide layer 149 are performed to supply oxygen to the insulating layer 110c will be described.

[0181] The insulating layer 110c is preferably formed using a deposition method such as a sputtering method or a plasma-enhanced chemical vapor deposition (PECVD) method. In particular, when a sputtering method is used, a hydrogen gas need not be used as a deposition gas, whereby a film with a very small amount of hydrogen can be achieved. Thus, the semiconductor layer 108 can be prevented from being supplied with hydrogen, and the stability of the electrical characteristics of the transistor 100 can be achieved.

[0182] The insulating layer 110b and the insulating layer 110d preferably use a film that is not easily diffused with oxygen. Thus, the oxygen in the insulating layer 110c can be prevented from being transmitted to the substrate 102 side through the insulating layer 110b and to the conductive layer 112b and the insulating layer 106 side through the insulating layer 110d by heat. In other words, by sandwiching the insulating layer 110c with the insulating layer 110b and the insulating layer 110d, the oxygen in the insulating layer 110c can be enclosed. Thus, oxygen can be effectively supplied to the semiconductor layer 108.

[0183] In addition, the insulating layer 110b and the insulating layer 110d preferably use a film that is not easily diffused with hydrogen. Thus, hydrogen can be prevented from diffusing into the semiconductor layer 108 from the outside of the transistor through the insulating layer 110b or the insulating layer 110d.

[0184] As the insulating layer 110b and the insulating layer 110d, any one or more of the above-described oxide insulating film, nitride insulating film, oxynitride insulating film, and nitride oxide insulating film is preferably used, and any one or more of a silicon nitride film, a silicon nitride oxide film, a silicon oxynitride film, an aluminum oxide film, an aluminum oxynitride film, an aluminum nitride film, a hafnium oxide film, and a hafnium aluminate film is preferably used.

[0185] The insulating layer 110b and the insulating layer 110d preferably use any one or more of the above-described nitride insulating film and nitride oxide insulating film. Specifically, one or both of a silicon nitride film and a silicon nitride oxide film is preferably used as the insulating layer 110b and the insulating layer 110d.

[0186] A silicon nitride film and a silicon nitride oxide film can achieve a film that is less likely to release impurities (e.g., water and hydrogen) and less likely to transmit oxygen and hydrogen, and thus can be appropriately used as the insulating layer 110b and the insulating layer 110d.

[0187] In addition, the insulating layer 110b and the insulating layer 110d can each be formed using a film containing aluminum, for example. For example, the insulating layer 110b and the insulating layer 110d each are formed using an aluminum oxide film. The hydrogen content of the aluminum oxide film is lower than that of a silicon nitride film, and thus the aluminum oxide film is preferable.

[0188] The thickness of the insulating layer 110b and the insulating layer 110d is preferably greater than or equal to 5 nm and less than or equal to 200 nm, more preferably greater than or equal to 5 nm and less than or equal to 150 nm, further preferably greater than or equal to 5 nm and less than or equal to 100 nm, still further preferably greater than or equal to 10 nm and less than or equal to 70 nm, yet further preferably greater than or equal to 10 nm and less than or equal to 50 nm, and yet further preferably greater than or equal to 20 nm and less than or equal to 50 nm. With the thickness of the insulating layer 110b and the insulating layer 110d in the above range, the oxygen vacancy in the semiconductor layer 108, particularly in the channel formation region, can be reduced. Note that the thickness of the insulating layer 110b and the insulating layer 110d can be the same or different.

[0189] For example, it is preferable that the insulating layer 110b and the insulating layer 110d each be formed using a silicon nitride film or a silicon oxynitride film, and the insulating layer 110c be formed using a silicon oxide film or a silicon oxynitride film.

[0190] [Semiconductor Layer 108]

[0191] The semiconductor layer 108 includes a metal oxide (also referred to as an oxide semiconductor) which exhibits semiconductor properties.

[0192] There is no particular limitation on the crystallinity of the semiconductor material used for the semiconductor layer 108, and an amorphous semiconductor, a single crystal semiconductor, or a semiconductor having crystallinity other than single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor including a crystalline region in part of the semiconductor) can be used. The use of a single crystal semiconductor or a semiconductor having crystallinity can suppress deterioration in the characteristics of the transistor, and is thus preferable.

[0193] The band gap of the metal oxide used for the semiconductor layer 108 is preferably greater than or equal to 2.0 eV, more preferably greater than or equal to 2.5 eV.

[0194] As the metal oxide which can be used for the semiconductor layer 108, indium oxide, gallium oxide, and zinc oxide can be given, for example. The metal oxide preferably contains at least indium or zinc. Further, the metal oxide preferably contains two or more kinds selected from indium, an element M, and zinc. The element M is a metal element or a semi-metal element having a high bond energy with oxygen, and is a metal element or a semi-metal element having a higher bond energy with oxygen than indium, for example. As the element M, specifically, aluminum, gallium, tin, yttrium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zirconium, molybdenum, hafnium, tantalum, tungsten, lanthanum, cerium, neodymium, magnesium, calcium, strontium, barium, boron, silicon, germanium, and antimony, or the like can be given. The element M contained in the metal oxide is preferably one or more kinds of the above elements, more preferably one or more kinds selected from aluminum, gallium, tin, and yttrium, and further preferably gallium. Note that in this specification and the like, a metal element and a semi-metal element are collectively referred to as a "metal element", and the "metal element" described in this specification and the like sometimes includes a semi-metal element.

[0195] The semiconductor layer 108 can be formed using, for example, indium zinc oxide (In-Zn oxide, also referred to as IZO (registered trademark)), indium tin oxide (In-Sn oxide), indium titanium oxide (In-Ti oxide), indium gallium oxide (In-Ga oxide), indium gallium aluminum oxide (In-Ga-Al oxide), indium gallium tin oxide (In-Ga-Sn oxide), gallium zinc oxide (Ga-Zn oxide, also referred to as GZO), aluminum zinc oxide (Al-Zn oxide, also referred to as AZO), indium aluminum zinc oxide (In-Al-Zn oxide, also referred to as IAZO), indium tin zinc oxide (In-Sn-Zn oxide, also referred to as ITZO (registered trademark)), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium zinc oxide (In-Ga-Zn oxide, also referred to as IGZO), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide, also referred to as IGZTO), indium gallium aluminum zinc oxide (In-Ga-Al-Zn oxide, also referred to as IGAZO, IGZAO, or IAGZO), or the like. Alternatively, indium tin oxide containing silicon, gallium tin oxide (Ga-Sn oxide), aluminum tin oxide (Al-Sn oxide), or the like can be used.

[0196] When the proportion of the number of atoms of indium to the sum of the numbers of atoms of all metal elements in the metal oxide is increased, the field-effect mobility of the transistor can be increased. In addition, a transistor with a large on-state current can be realized.

[0197] Note that a metal oxide can also be used instead of indium or in addition to indium. A metal oxide in which a metal element having a large number of orbitals is contained has a high carrier mobility. Thus, by containing a metal element having a large number of orbitals, the field-effect mobility of a transistor can be increased in some cases. As the metal element having a large number of orbitals, a metal element belonging to Group 5 or a metal element belonging to Group 6 can be given. Specifically, yttrium, zirconium, silver, cadmium, tin, antimony, barium, lead, bismuth, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, and europium can be given. Note that lanthanum, cerium, praseodymium, neodymium, promethium, samarium, and europium are called rare earth elements.

[0198] In addition, the metal oxide can contain one or plural kinds of non-metal elements. When the metal oxide contains a non-metal element, the field-effect mobility of a transistor can be increased in some cases because of an increase in carrier concentration or a narrowing of a band gap, or the like.

[0199] In addition, when the proportion of the number of atoms of zinc to the sum of the number of atoms of all metal elements in the metal oxide is increased, the metal oxide has high crystallinity and diffusion of impurities in the metal oxide can be inhibited. Thus, variation in electrical characteristics of a transistor can be inhibited and reliability can be increased.

[0200] In addition, when the proportion of the number of atoms of the element M to the sum of the number of atoms of all metal elements in the metal oxide is increased, formation of an oxygen vacancy in the metal oxide can be inhibited. Thus, generation of carriers due to an oxygen vacancy can be inhibited and a transistor with a small off-state current can be formed. In addition, variation in electrical characteristics of a transistor can be inhibited and reliability can be increased.

[0201] The electrical characteristics and reliability of a transistor vary depending on the composition of the metal oxide used for the semiconductor layer 108. Thus, by changing the composition of the metal oxide depending on the electrical characteristics and reliability required for a transistor, a semiconductor device with excellent electrical characteristics and high reliability can be realized.

[0202] When the metal oxide is an In-M-Zn oxide, the atomic ratio of In to the atomic ratio of M in the In-M-Zn oxide is preferably higher than or equal to the atomic ratio of M. As the atomic ratio of metal elements of such an In-M-Zn oxide, for example, In:M:Zn = 1:1:1, In:M:Zn = 1:1:1.2, In:M:Zn = 2:1:3, In:M:Zn = 3:1:1, In:M:Zn = 3:1:2, In:M:Zn = 4:2:3, In:M:Zn = 4:2:4.1, In:M:Zn = 5:1:3, In:M:Zn = 5:1:6, In:M:Zn = 5:1:7, In:M:Zn = 5:1:8, In:M:Zn = 6:1:6, In:M:Zn = 5:2:5, and the like, or compositions in the vicinity thereof can be given. Further, the vicinity includes a range of ±30% of the desired atomic ratio. By increasing the atomic ratio of indium in the metal oxide, the on-state current or the field-effect mobility of the transistor, or the like can be increased.

[0203] Further, the atomic ratio of In to the atomic ratio of M in the In-M-Zn oxide can be lower than the atomic ratio of M. As the atomic ratio of metal elements of such an In-M-Zn oxide, for example, In:M:Zn = 1:3:2, In:M:Zn = 1:3:3, In:M:Zn = 1:3:4, and the like, or compositions in the vicinity thereof can be given. By increasing the proportion of the atomic number of M in the metal oxide, generation of oxygen vacancies can be suppressed.

[0204] Note that when a plurality of metal elements are included as the element M, the total of the proportions of the atomic numbers of the metal elements can be the proportion of the atomic number of the element M.

[0205] In this specification and the like, the proportion of the atomic number of indium to the sum of the atomic numbers of all the metal elements contained is sometimes referred to as the indium content. The same applies to other metal elements.

[0206] The metal oxide can be formed using a sputtering method or an ALD method as appropriate. Note that in the case of forming the metal oxide using a sputtering method, the composition of the metal oxide after deposition is sometimes different from that of the target. In particular, the indium content in the metal oxide after deposition is sometimes reduced to about 50% of that of the target.

[0207] The semiconductor layer 108 can also have a stacked structure including two or more metal oxide layers. The compositions of the two or more metal oxide layers included in the semiconductor layer 108 can be the same or substantially the same. By employing a stacked structure of metal oxide layers having the same composition, the same sputtering target can be used, for example, so that manufacturing cost can be reduced.

[0208] The composition of the two or more metal oxide layers included in the semiconductor layer 108 can also be different from one another. For example, a stacked-layer structure of a first metal oxide layer having a composition of In:M:Zn = 1 : 3 : 4 [atomic ratio] or the vicinity thereof and a second metal oxide layer having a composition of In:M:Zn = 1 : 1 : 1 [atomic ratio] or the vicinity thereof provided on the first metal oxide layer can be appropriately used. Further, as the element M, gallium, aluminum, or tin is particularly preferable. For example, a stacked-layer structure selected from any one of indium oxide, indium gallium oxide, and IGZO and any one of IAZO, IAGZO, and ITZO (registered trademark) can be used.

[0209] The semiconductor layer 108 preferably includes a metal oxide layer having crystallinity. As a structure of a metal oxide having crystallinity, for example, a CAAC (c-axis aligned crystal) structure, a polycrystal structure, or a microcrystal (nc: nano-crystal) structure can be given. By using a metal oxide layer having crystallinity for the semiconductor layer 108, the density of defect states in the semiconductor layer 108 can be reduced, and thus a semiconductor device with high reliability can be realized.

[0210] The higher the crystallinity of the metal oxide layer used for the semiconductor layer 108, the lower the density of defect states in the semiconductor layer 108 can be. On the other hand, by using a metal oxide layer with low crystallinity, a transistor capable of flowing a large current can be realized.

[0211] When a metal oxide layer is formed by a sputtering method, the higher the substrate temperature (temperature of a stage) at the time of formation, the higher the crystallinity of the metal oxide layer that can be formed. Further, the higher the flow rate ratio of an oxygen gas (hereinafter, also referred to as an oxygen flow rate) with respect to the entire deposition gas used at the time of formation, the higher the crystallinity of the metal oxide layer that can be formed.

[0212] The semiconductor layer 108 can also have a stacked-layer structure of two or more metal oxide layers having different crystallinity. For example, the semiconductor layer 108 can have a stacked-layer structure of a first metal oxide layer and a second metal oxide layer provided on the first metal oxide layer, and the second metal oxide layer can include a region having higher crystallinity than the first metal oxide layer. Alternatively, the second metal oxide layer can include a region having lower crystallinity than the first metal oxide layer. At this time, the composition of the first metal oxide layer and the second metal oxide layer can be different, the same, or substantially the same.

[0213] The thickness of the semiconductor layer 108 is preferably greater than or equal to 3 nm and less than or equal to 200 nm, more preferably greater than or equal to 3 nm and less than or equal to 100 nm, more preferably greater than or equal to 5 nm and less than or equal to 100 nm, more preferably greater than or equal to 10 nm and less than or equal to 100 nm, more preferably greater than or equal to 10 nm and less than or equal to 70 nm, more preferably greater than or equal to 15 nm and less than or equal to 70 nm, more preferably greater than or equal to 15 nm and less than or equal to 50 nm, more preferably greater than or equal to 20 nm and less than or equal to 50 nm.

[0214] In the case where an oxide semiconductor is used for the semiconductor layer 108, hydrogen in the oxide semiconductor sometimes reacts with oxygen bonded to a metal atom to become water, and an oxygen vacancy (V O ) is formed in the oxide semiconductor. Further, a defect (hereinafter referred to as V O H) in which hydrogen enters an oxygen vacancy is used as a donor to generate an electron as a carrier. In addition, an electron as a carrier is sometimes generated because part of hydrogen is bonded to oxygen bonded to a metal atom. Thus, a transistor using an oxide semiconductor containing a large amount of hydrogen tends to be always on (i.e., the threshold voltage is negative). Further, because hydrogen in the oxide semiconductor easily moves due to heat, an electric field, or the like, the reliability of a transistor can be reduced when the oxide semiconductor contains a large amount of hydrogen.

[0215] When an oxide semiconductor is used as the semiconductor layer 108, it is preferable to reduce V O H in the semiconductor layer 108 as much as possible so that it is high-purity intrinsic or substantially high-purity intrinsic. In order to obtain such an oxide semiconductor in which V O H is sufficiently reduced, it is important to remove impurities such as water and hydrogen from the oxide semiconductor (sometimes referred to as dehydration or dehydrogenation treatment) and to supply oxygen to the oxide semiconductor to repair an oxygen vacancy. By using an oxide semiconductor in which impurities such as V O H are sufficiently reduced for a channel formation region of a transistor, stable electric characteristics can be given. Note that the treatment in which oxygen is supplied to the oxide semiconductor to repair an oxygen vacancy is referred to as oxidation treatment.

[0216] When an oxide semiconductor is used as the semiconductor layer 108, the carrier concentration of the oxide semiconductor used for a region serving as a channel formation region is preferably 1 x 10 18 cm -3 -2 or lower, more preferably 1 x 10 17 cm -3 -2 or lower, further preferably 1 x 10 16 cm -3 -2 or lower, more preferably 1 x 10 13 cm -3 -2 or lower, further preferably 1 x 10 12 cm -3The lower limit value of the carrier concentration of the oxide semiconductor used for the region serving as the channel formation region is not particularly limited, and for example, it can be set to 1 x 10 -9 cm -3 .

[0217] The field-effect mobility of a transistor using an oxide semiconductor (hereinafter referred to as an OS transistor) is very high compared to that of a transistor using amorphous silicon. In addition, the off-state current of the OS transistor is extremely low, and the OS transistor can hold a charge stored in a capacitor connected in series to the transistor for a long period. Furthermore, by using the OS transistor, the power consumption of a semiconductor device can be reduced.

[0218] The OS transistor has a small change in electrical characteristics due to irradiation with a radiation ray, i.e., high resistance to a radiation ray, and thus can be appropriately used in an environment where a radiation ray is likely to be incident. The OS transistor can also be said to have high reliability against a radiation ray. For example, the OS transistor can be appropriately used for a pixel circuit of a flat panel detector for X-rays. Furthermore, the OS transistor can be appropriately used for a semiconductor device used in space. As a radiation ray, electromagnetic radiation rays (e.g., X-rays and γ-rays) and particle radiation rays (e.g., α-rays, β-rays, mesic rays, proton rays, and neutron rays) can be given.

[0219] As other semiconductor materials that can be used for the semiconductor layer 108, a semiconductor composed of a single element or a compound semiconductor can be given, for example. As a semiconductor composed of a single element, silicon or germanium can be given, for example. As a compound semiconductor, gallium arsenide and silicon germanium can be given, for example. In addition to these, as a compound semiconductor, an organic semiconductor and a nitride semiconductor can be given, for example. Note that the above oxide semiconductor is one of compound semiconductors. Furthermore, these semiconductor materials can contain impurities as dopants.

[0220] As silicon that can be used for the semiconductor layer 108, single crystal silicon, polycrystalline silicon, microcrystalline silicon, and amorphous silicon can be given. As polycrystalline silicon, low-temperature polycrystalline silicon (LTPS: Low Temperature Poly Silicon) can be given, for example.

[0221] A transistor in which amorphous silicon is used for the semiconductor layer 108 can be formed over a large glass substrate and can be manufactured at low cost. A transistor in which polycrystalline silicon is used for the semiconductor layer 108 has high field-effect mobility and can operate at high speed. Furthermore, a transistor in which microcrystalline silicon is used for the semiconductor layer 108 has high field-effect mobility compared to a transistor in which amorphous silicon is used and can operate at high speed.

[0222] The semiconductor layer 108 can also include a layered substance that functions as a semiconductor. A layered substance is a general term for a group of materials that have a layered crystal structure. The layered crystal structure is a structure in which layers formed by covalent bonds or ionic bonds are stacked by bonds such as van der Waals bonds, which are weaker than covalent bonds and ionic bonds. A layered substance has high conductivity in a unit layer, i.e., has high two-dimensional conductivity. By using a material that functions as a semiconductor and has high two-dimensional conductivity for the channel formation region, a transistor can be provided in which the on-state current is large.

[0223] As the above layered substance, for example, graphene, silicene, a chalcogenide, or the like can be given. A chalcogenide is a compound containing an oxygen group element (a group 16 element). Further, as the chalcogenide, a transition metal chalcogenide, a group 13 chalcogenide, or the like can be given. As the transition metal chalcogenide that can be used as a semiconductor layer of a transistor, specifically, molybdenum sulfide (typically, MoS2), molybdenum selenide (typically, MoSe2), molybdenum telluride (typically, MoTe2), tungsten sulfide (typically, WS2), tungsten selenide (typically, WSe2), tungsten telluride (typically, WTe2), hafnium sulfide (typically, HfS2), hafnium selenide (typically, HfSe2), zirconium sulfide (typically, ZrS2), zirconium selenide (typically, ZrSe2), or the like can be given.

[0224] [Conductive layer 112a, conductive layer 112b]

[0225] Each of the conductive layer 112a and the conductive layer 112b can have a single-layer structure or a stacked-layer structure of two or more layers. As a material that can be used for the conductive layer 112a and the conductive layer 112b, for example, one or more of chromium, copper, aluminum, gold, silver, zinc, tantalum, titanium, tungsten, manganese, nickel, iron, cobalt, molybdenum, and niobium and an alloy containing one or more of the above metals as a component can be given. The conductive layer 112a and the conductive layer 112b can be appropriately formed using a conductive material having a low resistivity, containing one or more of copper, silver, gold, and aluminum. Among them, copper or aluminum is particularly advantageous in terms of mass productivity, and thus is preferable.

[0226] The conductive layer 112a and the conductive layer 112b can use a metal oxide having conductivity (also referred to as an oxide conductor). As the oxide conductor, for example, indium oxide, zinc oxide, an In-Sn oxide (ITO), an In-Zn oxide (also referred to as IZO (registered trademark)), an In-W oxide, an In-W-Zn oxide, an In-Ti oxide, an In-Ti-Sn oxide, an In-Sn-Si oxide (ITO containing silicon, also referred to as ITSO), zinc oxide to which gallium is added, and an In-Ga-Zn oxide can be given. In particular, it is preferable to use a conductive oxide containing indium because of its high conductivity.

[0227] An oxygen vacancy is formed in a metal oxide having a semiconductor property, and hydrogen is added to the oxygen vacancy to form a donor level near the conduction band. As a result, the conductivity of the metal oxide is increased, and the metal oxide becomes a conductor. The metal oxide that becomes a conductor can be referred to as an oxide conductor.

[0228] The conductive layer 112a and the conductive layer 112b can also have a stacked structure of a conductive film including the oxide conductor (metal oxide) described above and a conductive film including a metal or an alloy. By using a conductive film including a metal or an alloy, the wiring resistance can be reduced.

[0229] As the conductive layer 112a and the conductive layer 112b, a Cu-X alloy film (X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti) can also be used. By using a Cu-X alloy film, processing can be performed by a wet etching method, so that manufacturing cost can be reduced.

[0230] The conductive layer 112a and the conductive layer 112b each include a region in contact with the semiconductor layer 108. When an oxide semiconductor is used as the semiconductor layer 108 and a metal that is easily oxidized (e.g., aluminum) is used as the conductive layer 112a or the conductive layer 112b, an insulating oxide (e.g., aluminum oxide) is formed between the conductive layer 112a or the conductive layer 112b and the semiconductor layer 108, which can hinder conduction therebetween. Thus, the conductive layer 112a and the conductive layer 112b preferably use a conductive material that is not easily oxidized, a conductive material that maintains low resistance even when oxidized, or an oxide conductor. With this structure, the contact resistance between the conductive layer 112a or the conductive layer 112b and the semiconductor layer 108 can be reduced.

[0231] In addition, when the conductive layer 112a or the conductive layer 112b has a stacked structure, at least a layer in contact with the semiconductor layer 108 preferably uses a conductive material that is not easily oxidized, a conductive material that maintains low resistance even when oxidized, or an oxide conductor. A layer in the conductive layer 112a and the conductive layer 112b that is not in contact with the semiconductor layer 108 can use various conductive materials, and preferably uses a material with high conductivity (which can also be referred to as a material with high electrical resistivity or a material with low specific resistance). With this structure, the conductive layer 112a and the conductive layer 112b can be formed as a layer suitable for use as a wiring.

[0232] As a conductive material that is not easily oxidized or a conductive material that maintains low resistance even when oxidized, titanium, tantalum nitride, titanium nitride, a nitride including titanium and aluminum, a nitride including tantalum and aluminum, ruthenium, ruthenium oxide, ruthenium nitride, an oxide including strontium and ruthenium, and an oxide including lanthanum and nickel can be given.

[0233] Specific examples of the oxide conductor are described above.

[0234] The conductive layer 112a and the conductive layer 112b can also use a nitride conductor. As the nitride conductor, for example, a tantalum nitride and a titanium nitride can be given.

[0235] The conductive layer 112a and the conductive layer 112b can use the same material or different materials.

[0236] It is preferable that a conductive material that is not easily oxidized, a conductive material that maintains low resistance even if oxidized, or an oxide conductor be used for the layer of the conductive layer 112a and the conductive layer 112b that contacts the semiconductor layer 108, and a material having higher conductivity than the material used for the layer that contacts the semiconductor layer 108 be used for at least one of the other layers. Thereby, the contact resistance of the semiconductor layer 108 and the conductive layer 112a and the contact resistance of the semiconductor layer 108 and the conductive layer 112b can be suppressed from increasing. Further, the wiring resistance of the conductive layer 112a and the conductive layer 112b can be reduced.

[0237] As a specific structure of the conductive layer 112a and the conductive layer 112b, for example, a stacked structure of one or more metal films and one or more oxide conductor films or a stacked structure including one or more metal films between a pair of oxide conductor films can be given. As the one or more metal films, for example, a single-layer structure of a tungsten film, a single-layer structure of a titanium film, a single-layer structure of a copper film, a two-layer structure of a titanium film and an aluminum film, and a three-layer structure of a titanium film, an aluminum film, and a titanium film can be given. Further, as the oxide conductor film, for example, a single-layer structure of an In-Zn oxide film, a single-layer structure of an ITO film, and a single-layer structure of an ITSO film can be given.

[0238] [Conductive layer 104]

[0239] The conductive layer 104 can adopt a single-layer structure or a stacked structure of two or more layers. As a material that can be used for the conductive layer 104, for example, one or more of chromium, copper, aluminum, gold, silver, zinc, tantalum, titanium, tungsten, manganese, nickel, iron, cobalt, molybdenum, and niobium and an alloy including one or more of the above metals as a component can be given. As the conductive layer 104, a conductive material having low resistivity including one or more of copper, silver, gold, and aluminum can be appropriately used. Among them, copper or aluminum is particularly advantageous in terms of mass productivity, and thus is preferable.

[0240] As the conductive layer 104, the above-described oxide conductor can be used.

[0241] As the conductive layer 104, a stacked structure of a conductive film including the above-described oxide conductor (metal oxide) and a conductive film including a metal or an alloy can also be adopted. By using the conductive film including a metal or an alloy, the wiring resistance can be reduced.

[0242] As the conductive layer 104, a Cu-X alloy film (X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti) can also be used. By using a Cu-X alloy film, processing can be performed using a wet etching method, so manufacturing cost can be reduced.

[0243] For example, as the conductive layer 104, a three-layer structure of a titanium film, an aluminum film, and a titanium film is preferably used. Alternatively, as the conductive layer 104, a two-layer structure of a titanium film and an aluminum film is preferably used. Alternatively, as the conductive layer 104, a two-layer structure of a titanium film or a molybdenum film and a copper film is preferably used.

[0244] Note that the materials used for the conductive layer 112a, the conductive layer 112b, and the conductive layer 104 can be the same or at least a part of them can be different.

[0245] [Insulating layer 106]

[0246] The insulating layer 106 can have a single-layer structure or a stacked-layer structure of two or more layers. The insulating layer 106 preferably includes one or more inorganic insulating films. As the inorganic insulating film, for example, an oxide insulating film, a nitride insulating film, an oxynitride insulating film, and a nitride oxide insulating film can be given. Specific examples of these inorganic insulating films are described above.

[0247] The insulating layer 106 has a portion in contact with the semiconductor layer 108. When the semiconductor layer 108 uses an oxide semiconductor, at least a film of the films included in the insulating layer 106 which is in contact with the semiconductor layer 108 is preferably an oxide insulating film or an oxynitride insulating film. Further, it is more preferable that the insulating layer 106 include a film which releases oxygen by heating.

[0248] Specifically, when the insulating layer 106 has a single-layer structure, the insulating layer 106 is preferably formed using a silicon oxide film or a silicon oxynitride film.

[0249] Further, the insulating layer 106 can have a stacked-layer structure of an oxide insulating film or an oxynitride insulating film which is in contact with the semiconductor layer 108 and a nitride insulating film or a nitride oxide insulating film which is in contact with the conductive layer 104. As the oxide insulating film or the oxynitride insulating film, a silicon oxide film or a silicon oxynitride film is preferably used, for example. As the nitride insulating film or the nitride oxide insulating film, a silicon nitride film or a silicon nitride oxide film is preferably used.

[0250] A silicon nitride film and a silicon nitride oxide film have characteristics that they hardly release impurities (e.g., water and hydrogen) and are not easily permeable to oxygen and hydrogen, and thus can be appropriately used as the insulating layer 106. Since diffusion of impurities from the insulating layer 106 to the semiconductor layer 108 is inhibited, favorable electrical characteristics of transistors can be achieved and reliability can be improved.

[0251] Note that in a micro transistor, a leakage current sometimes increases when the thickness of a gate insulating layer is small. By using a material with a high relative dielectric constant (also referred to as a high-k material) for the gate insulating layer, low voltage operation of the transistor can be achieved while the physical thickness is kept. As the high-k material which can be used for the insulating layer 106, gallium oxide, hafnium oxide, zirconium oxide, an oxide containing aluminum and hafnium, an oxynitride containing aluminum and hafnium, an oxide containing silicon and hafnium, an oxynitride containing silicon and hafnium, and a nitride containing silicon and hafnium, for example, can be given.

[0252] [Substrate 102]

[0253] Although there is no particular limitation on the material of the substrate 102, at least heat resistance to withstand a subsequent heat treatment is needed. For example, a single crystal semiconductor substrate or a polycrystal semiconductor substrate using silicon or silicon carbide as a material, a compound semiconductor substrate of silicon germanium or the like, an SOI substrate, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, or a resin substrate can be used as the substrate 102. Further, a semiconductor element can be provided over the substrate 102. Note that the shape of the semiconductor substrate and the insulating substrate can be circular or angular.

[0254] As the substrate 102, a flexible substrate can also be used, and the transistor 100 and the like can be directly formed over the flexible substrate. Alternatively, a separation layer can be provided between the substrate 102 and the transistor 100 and the like. The separation layer can be used when part or all of a semiconductor device is manufactured over the separation layer, and then separated from the substrate 102 and transferred to another substrate. At this time, the transistor 100 and the like can be transferred to a substrate with low heat resistance or a flexible substrate.

[0255] [Variation of Transistor 100]

[0256] FIGS. 5 to 10 illustrate a variation of the transistor 100.

[0257] [Transistor 100A]

[0258] Figure 5A and Figure 5B A cross-sectional view of the transistor 100A is illustrated. Note that the top view of the transistor 100A is the same as that of the transistor 100, and thus the description of the top view of the transistor 100 can be referred to. Figure 1A .

[0259] In the transistor 100, an example in which the insulating layer 110 is a three-layer structure is illustrated, and in the transistor 100A, an example in which the insulating layer 110 is a five-layer structure is illustrated. Specifically, Figure 5A and Figure 5BThe insulating layer 110 shown has a stacked structure of the insulating layer 110a over the substrate 102 and the conductive layer 112a, the insulating layer 110b over the insulating layer 110a, the insulating layer 110c over the insulating layer 110b, the insulating layer 110d over the insulating layer 110c, and the insulating layer 110e over the insulating layer 110d.

[0260] There is a region (a bias region) in the semiconductor layer 108 to which a gate electric field is not easily applied. The insulating layer 110a is preferably provided so as to be in contact with the bias region.

[0261] The insulating layer 110a includes a region having a higher hydrogen content than the insulating layer 110b. Further, the insulating layer 110a preferably includes a region having a higher hydrogen content than the insulating layer 110d.

[0262] When the resistance of the bias region is high, the field-effect mobility of the transistor is sometimes decreased. When the insulating layer 110a is a layer with a high hydrogen content, a region in the semiconductor layer 108 in contact with the insulating layer 110a and its vicinity can be made low in resistance. Thus, the decrease in the field-effect mobility due to the bias region can be suppressed.

[0263] The insulating layer 110a is preferably a layer from which hydrogen is released by heating. The insulating layer 110a releases hydrogen due to heat applied in the manufacturing process of the transistor 100A, and thus hydrogen can be supplied to the semiconductor layer 108. By supplying hydrogen to the bias region of the semiconductor layer 108, the bias region can be made low in resistance and the decrease in the field-effect mobility can be suppressed.

[0264] Similarly, the insulating layer 110e includes a region having a higher hydrogen content than the insulating layer 110d. Further, the insulating layer 110e preferably includes a region having a higher hydrogen content than the insulating layer 110b.

[0265] When the insulating layer 110e is a layer with a high hydrogen content, a region in the semiconductor layer 108 in contact with the insulating layer 110e and its vicinity can be made low in resistance.

[0266] The insulating layer 110e is preferably a layer from which hydrogen is released by heating. The insulating layer 110e releases hydrogen due to heat applied in the manufacturing process of the transistor 100A, and thus hydrogen can be supplied to the semiconductor layer 108. Thus, a low-resistance region can be formed in the vicinity of a region of the semiconductor layer 108 in contact with the conductive layer 112b.

[0267] In the transistor 100A, in the semiconductor layer 108, a region in contact with the insulating layer 110a is provided between a region in contact with the conductive layer 112a and a region in contact with the insulating layer 110c which is an i-type region, as a low-resistance region. Here, when the conductive layer 112a is used as a drain electrode and the conductive layer 112b is used as a source electrode, it can be said that the semiconductor layer 108 includes a low-resistance region between a region in contact with the drain electrode and a channel formation region. Thus, a high electric field is not easily generated in the vicinity of the drain region, and generation of hot carriers can be suppressed, which can suppress deterioration of the transistor.

[0268] Similarly, in the transistor 100A, in the semiconductor layer 108, a region in contact with the insulating layer 110e is provided between a region in contact with the conductive layer 112b and a region in contact with the insulating layer 110c which is an i-type region, as a low-resistance region. Here, when the conductive layer 112a is used as a source electrode and the conductive layer 112b is used as a drain electrode, it can be said that the semiconductor layer 108 includes a low-resistance region between a region in contact with the drain electrode and a channel formation region. Thus, a high electric field is not easily generated in the vicinity of the drain region, and generation of hot carriers can be suppressed, which can suppress deterioration of the transistor.

[0269] Thus, the transistor of one embodiment of the present application can have high reliability even when the conductive layer 112a or the conductive layer 112b is a drain electrode. Thus, the design freedom of a semiconductor device can be improved.

[0270] The hydrogen content of the insulating layer 110b is lower than that of the insulating layer 110a. The hydrogen content of the insulating layer 110d is lower than that of the insulating layer 110e. Thus, diffusion of hydrogen from the insulating layer 110b or the insulating layer 110d to the insulating layer 110c and a region of the semiconductor layer 108 to which a sufficient gate electric field is applied (a region which is desired to be i-type) can be suppressed.

[0271] As described above, the insulating layer 110b and the insulating layer 110d preferably use a film from which hydrogen is not easily diffused. Thus, diffusion of hydrogen from the insulating layer 110a to the semiconductor layer 108 through the insulating layer 110b can be suppressed. Further, diffusion of hydrogen from the insulating layer 110e to the semiconductor layer 108 through the insulating layer 110d can be suppressed.

[0272] As the insulating layer 110a and the insulating layer 110e, any one or a plurality of the above-described oxide insulating film, nitride insulating film, oxynitride insulating film, and nitride oxide insulating film is preferably used, and any one or a plurality of a silicon nitride film, a silicon nitride oxide film, a silicon oxynitride film, an aluminum oxide film, an aluminum oxynitride film, an aluminum nitride film, a hafnium oxide film, and a hafnium aluminate film is preferably used.

[0273] The insulating layers 110a and 110e preferably use any one or more of the above-mentioned nitride insulating films and oxynitride insulating films. Specifically, the insulating layers 110a and 110e preferably use one or both of a silicon nitride film and a silicon oxynitride film.

[0274] The silicon nitride film and the silicon oxynitride film can be made to be a film from which hydrogen is released in large amounts by changing deposition conditions (e.g., deposition gas or power at the time of deposition), and thus can be appropriately used as the insulating layers 110a and 110e.

[0275] In the semiconductor layer 108, it is preferable that the region in contact with the insulating layer 110b has a higher resistance than the region in contact with the insulating layer 110a and a lower resistance than the region in contact with the insulating layer 110c. In the semiconductor layer 108, the region in contact with the insulating layer 110b can be an n - type region or an n - region. In the semiconductor layer 108, oxygen supplied from the insulating layer 110c reaches not only the region in contact with the insulating layer 110c but also the region in contact with the insulating layer 110b and its vicinity. Likewise, in the semiconductor layer 108, hydrogen supplied from the insulating layer 110a reaches not only the region in contact with the insulating layer 110a but also the region in contact with the insulating layer 110b and its vicinity. Here, in the case where the insulating layer 110a is not provided, the region in contact with the insulating layer 110b and its vicinity in the semiconductor layer 108 has a higher resistance by being supplied with oxygen through the insulating layer 110c. In the semiconductor layer 108, when a high-resistance region is included between the channel formation region and the region in contact with the drain electrode, the on-state current of the transistor can decrease. On the other hand, in the case where the insulating layer 110a having a high hydrogen content is provided, the region in contact with the insulating layer 110b and its vicinity in the semiconductor layer 108 can be inhibited from being high-resistance by being supplied with hydrogen, and thus the decrease in the on-state current of the transistor can be inhibited, and thus is preferable.

[0276] For example, it is preferable that the insulating layers 110a, 110b, 110d, and 110e use a silicon nitride film or a silicon oxynitride film, and the insulating layer 110c use a silicon oxide film or a silicon oxynitride film.

[0277] For example, it is preferable that the insulating layers 110a and 110e use a silicon nitride film or a silicon oxynitride film, the insulating layers 110b and 110d use an aluminum oxide film, and the insulating layer 110c use a silicon oxide film or a silicon oxynitride film.

[0278] Thus, by providing the semiconductor layer 108 in contact with the insulating layers 110a to 110e, the channel formation region in the semiconductor layer 108 can be positioned at a position where a sufficient gate electric field is applied. In addition, the offset region in the semiconductor layer 108 can be made low in resistance. Thus, the field-effect mobility of the transistor 100 can be kept high, and a transistor with high electric characteristics can be obtained.

[0279] The region of the semiconductor layer 108 in contact with the insulating layer 110 is provided between the region in contact with the conductive layer 112a and the region in contact with the conductive layer 112b. The insulating layer 110 has a structure in which the upper and lower portions of the insulating layer 110c are sandwiched by the insulating layers 110b and 110d each of which has a low hydrogen content, and the upper and lower portions of the three-layer structure are sandwiched by the insulating layers 110a and 110e each of which has a high hydrogen content. That is, the insulating layer 110 has a symmetric structure with respect to a line perpendicular to the up-down direction (the stacking direction). Thus, the semiconductor layer 108 can have an appropriate carrier concentration distribution in the channel length direction. Thus, the transistor can have high electric characteristics and high reliability.

[0280] The hydrogen content is lower than the main components of the insulating layer (e.g., nitrogen and silicon of the silicon nitride layer), and thus the hydrogen contents of the insulating layers 110a, 110b, 110d, and 110e are preferably compared by SIMS analysis.

[0281] Even when the insulating layers 110a and 110b each use a layer having the same main component (e.g., a silicon nitride layer), they can be distinguished by cross-sectional observation in some cases. For example, in a transmitted electron (TE) image of a scanning transmission electron microscope (STEM), the brightness of the insulating layer 110a is observed to be higher than that of the insulating layer 110b. Similarly, even when the insulating layers 110d and 110e each use a layer having the same main component, they can be distinguished by cross-sectional observation in some cases. For example, in a TE image of a STEM, the brightness of the insulating layer 110e is observed to be higher than that of the insulating layer 110d.

[0282] The thickness of each of the insulating layers 110a and 110e is preferably greater than or equal to 10 nm and less than or equal to 200 nm, more preferably greater than or equal to 20 nm and less than or equal to 150 nm, and still more preferably greater than or equal to 30 nm and less than or equal to 100 nm. Note that the thickness of the insulating layers 110a and 110e can be the same or different.

[0283] In the semiconductor layer 108, the region in contact with the insulating layer 110a and the region in contact with the insulating layer 110e are each used as a low-resistance region (also referred to as an n + type region or an n+ The region in contact with insulating layer 110c is used as a channel formation region. In semiconductor layer 108, the resistance of the region in contact with insulating layer 110b is sometimes higher than that of the region in contact with insulating layer 110a and lower than that of the region in contact with insulating layer 110c. Similarly, the resistance of the region in contact with insulating layer 110d is sometimes higher than that of the region in contact with insulating layer 110e and lower than that of the region in contact with insulating layer 110c. In this embodiment, the regions in semiconductor layer 108 in contact with insulating layer 110b and insulating layer 110d are described without including them in the channel formation region; however, these regions may also be included. Alternatively, the regions in semiconductor layer 108 in contact with insulating layer 110b and insulating layer 110d may be referred to as low-resistance regions. Low-resistance regions may also be used as source regions or drain regions.

[0284] It can be said that the channel length of transistor 100A is the shortest distance between the portion of semiconductor layer 108 that contacts insulating layer 110b and the portion that contacts insulating layer 110d when viewed in cross-section.

[0285] Furthermore, when the channel formation region includes both the region in semiconductor layer 108 that contacts insulating layer 110b and the region that contacts insulating layer 110d, the channel length can be considered to be the shortest distance between the portion of semiconductor layer 108 that contacts insulating layer 110a and the portion that contacts insulating layer 110e when viewed in cross-section. Additionally, the channel length is equivalent to the sum of the lengths of the side surfaces on the opening 141 side of insulating layers 110b, 110c, and 110d when viewed in cross-section.

[0286] [Transistor 100B]

[0287] Figure 6A and Figure 6B A cross-sectional view of transistor 100B is shown. Note that the top view of transistor 100B is the same as the top view of transistor 100, so it can be referred to. Figure 1A .

[0288] Figure 6A and Figure 6B Transistor 100B and transistor 100A shown Figure 5A and Figure 5B The difference is that the insulating layer 110 does not include the insulating layer 110a, and includes the insulating layer 109 between the substrate 102 and the conductive layer 112a.

[0289] The insulating layer 109 included in transistor 100B can be formed using the same material as the insulating layer 110a included in transistor 100A and has the same function.

[0290] Hydrogen released from the insulating layer 109 diffuses into the region of the conductive layer 112a that contacts the insulating layer 109. Additionally, the hydrogen diffused into the conductive layer 112a diffuses into the region of the semiconductor layer 108 that contacts the conductive layer 112a and its vicinity. This reduces the resistance of the region of the semiconductor layer 108 that contacts the conductive layer 112a and its vicinity. Therefore, the on-state current of the transistor can be increased, thereby enabling a semiconductor device capable of high-speed operation.

[0291] Furthermore, by providing the insulating layer 110b, the diffusion of hydrogen released from the insulating layer 109 into the insulating layer 110c and the channel formation region of the semiconductor layer 108 can be suppressed.

[0292] in addition, Figure 6C Show Figure 6B The example shown is a modified version of transistor 100B. Figure 6B An example is shown in which the insulating layer 109 is disposed on the entire top surface of the substrate 102, but it is not limited thereto and the insulating layer 109 may also be processed. Figure 6C An example is shown where the insulating layer 109 is disposed in an island-like pattern on the substrate 102. For example... Figure 6C As shown, the end of the insulating layer 109 can also be aligned or substantially aligned with the end of the conductive layer 112a. For example, it is preferable to use the same mask pattern to process the insulating layer 109 and the conductive layer 112a. This reduces the manufacturing cost of the transistor. Figure 6C In the middle, insulating layer 109 contacts insulating layer 110b in insulating layer 110. As described above, insulating layer 110b is a film in which hydrogen does not diffuse easily, thus it can suppress the diffusion of hydrogen from insulating layer 109 through insulating layer 110b to insulating layer 110c and the channel formation region of semiconductor layer 108.

[0293] [Transistor 100C, Transistor 100D, Transistor 100E]

[0294] Figure 7A The transistor 100C shown Figure 7B The transistor 100D shown and Figure 7C The transistor 100E shown differs from transistor 100 in that conductive layers 112a and 112b are stacked.

[0295] Figure 7A and Figure 7B The conductive layer 112a shown includes a conductive layer 182a and a conductive layer 122a on the conductive layer 182a. Figure 7A An example is shown where the end of conductive layer 182a is aligned with the end of conductive layer 122a. Figure 7BAn example in which the conductive layer 122a covers the top surface and the side surface of the conductive layer 182a is shown. Since the conductive layer 122a is a layer in contact with the semiconductor layer 108, it is preferable to use the above-described conductive material which is not easily oxidized, a conductive material which maintains low resistance even if oxidized, or an oxide conductor. The conductive layer 182a preferably uses a material having higher conductivity than the material used for the conductive layer 122a. Thereby, the contact resistance between the semiconductor layer 108 and the conductive layer 112a can be suppressed from becoming high, and the wiring resistance of the conductive layer 112a can be reduced.

[0296] Figure 7C The conductive layer 112a shown includes the conductive layer 183a, the conductive layer 182a on the conductive layer 183a, and the conductive layer 122a on the conductive layer 182a. Depending on the material of the conductive layer 182a, the adhesion to the formed surface (e.g., the top surface of the substrate 102) of the conductive layer 112a can be low, which can cause the manufacturing yield of the semiconductor device to decrease. Therefore, by using a material having higher adhesion to the formed surface than the conductive layer 182a as the conductive layer 183a, the manufacturing yield of the semiconductor device can be improved. In addition, the thickness of the conductive layer 183a can be made to be sufficient to have the effect of improving the adhesion to the formed surface of the conductive layer 112a, and can be smaller than the thickness of the conductive layer 182a and the conductive layer 122a. By reducing the thickness of the conductive layer 183a, the manufacturing cost can be reduced. Figure 7C An example in which the end portion of the conductive layer 183a is aligned with the end portion of the conductive layer 122a is shown. By processing the conductive layer 183a and the conductive layer 122a with the same mask pattern, the manufacturing cost can be reduced, and thus is preferable. As the conductive layer 183a, for example, an oxide conductor film such as an ITSO film is preferably used. In the case where the formed surface of the conductive layer 112a is a glass substrate or an oxide film, the adhesion of the conductive layer 112a to the formed surface of the conductive layer 112a can be improved when an oxide conductor film is used, as compared to a metal film such as a copper film. Furthermore, by using the same material as the conductive layer 122a, the conductive layer 183a and the conductive layer 122a can be easily processed in the same process, and thus the manufacturing cost can be reduced, and thus is preferable.

[0297] Figures 7A to 7C The conductive layer 112b shown includes the conductive layer 182b and the conductive layer 122b on the conductive layer 182b. Figure 7A An example in which the end portion of the conductive layer 182b is aligned with the end portion of the conductive layer 122b is shown. Figure 7BAn example is shown where conductive layer 122b covers the top and side surfaces of conductive layer 182b. Semiconductor layer 108 contacts the top and side surfaces of conductive layer 122b. Compared to conductive layer 182b, conductive layer 122b has a larger contact area with semiconductor layer 108; therefore, it is preferable to use a conductive material that is not easily oxidized, a conductive material that maintains low resistance even when oxidized, or an oxide conductor. Conductive layer 182b is preferably made of a material with higher conductivity than the material used for conductive layer 122b. This can suppress the increase of contact resistance between semiconductor layer 108 and conductive layer 112b, and reduce the wiring resistance of conductive layer 112b.

[0298] Note that the conductive layer 182b may also not have the opening 143. Viewed in cross-section, as... Figure 7A In that case, the conductive layer 182b can also be located on its left and right sides in a manner that sandwiches the opening 143, such as... Figure 7C As shown, the conductive layer 182b may also be located only on one of the left and right sides of the opening 143. Figure 7C An example is shown where the end of the conductive layer 182b is located on the right side of the opening 143 and the conductive layer 182b is not located on the left side of the opening 143.

[0299] [Transistor 100F]

[0300] Figure 8A A top view of transistor 100F is shown. Figure 8B It is along Figure 8A The cross-sectional view of the dashed-dot lines A1-A2 in the diagram. Figure 8C It is along Figure 8A The cross-sectional view of the dashed-dot line B1-B2 in the diagram.

[0301] The main difference between transistor 100F and transistor 100A is that, when viewed from above, opening 143 is larger than opening 141.

[0302] The end of the conductive layer 112b on the side of the opening 143 is located outside the end of the insulating layer 110 on the side of the opening 141.

[0303] The semiconductor layer 108 is in contact with the top and side surfaces of the conductive layer 112b, the top and side surfaces of the insulating layer 110e, the side surface of the insulating layer 110d, the side surface of the insulating layer 110c, the side surface of the insulating layer 110b, the side surface of the insulating layer 110a, and the top surface of the conductive layer 112a.

[0304] Semiconductor layer 108 preferably contains the aforementioned impurity elements at least in the regions that contact the top surface of conductive layer 112a and the top surface of conductive layer 112b. Figure 8B and Figure 8CAn example is shown in which the low-resistance region 108n is provided in the region in contact with the top surface of the conductive layer 112a and the region in contact with the top surface of the conductive layer 112b. Further, the low-resistance region 108n can also be provided in one or both of the region in contact with the side surface of the conductive layer 112b and the region in contact with the top surface of the insulating layer 110e.

[0305] [Transistor 100G]

[0306] Figure 9A A plan view of the transistor 100G is shown. Figure 9B is a cross-sectional view taken along the dotted line A1-A2 in Figure 9A Figure 9C is a cross-sectional view taken along the dotted line B1-B2 in Figure 9A

[0307] The transistor 100G differs from the transistor 100A in that the semiconductor layer 108 is in contact with the side surface of the conductive layer 112b on the side other than the side facing the opening portion 143 (the side opposite to the opening portion 143).

[0308] There is no particular limitation on the top surface shape and size of the semiconductor layer 108 and the conductive layer 112b. The end portion of the semiconductor layer 108 can be aligned with the end portion of the conductive layer 112b, can be positioned inside the end portion of the conductive layer 112b, or can be positioned outside the end portion of the conductive layer 112b.

[0309] As shown in Figure 9B , the semiconductor layer 108 of the transistor 100C covers the side surface of the conductive layer 112b on the side other than the side facing the opening portion 143. The end portion of the semiconductor layer 108 is positioned outside the end portion of the conductive layer 112b and is in contact with the insulating layer 110. In addition, the left end portion of the semiconductor layer 108 in Figure 9C covers the end portion of the conductive layer 112b and is in contact with the insulating layer 110. In addition, the right end portion of the semiconductor layer 108 in Figure 9C is in contact with the conductive layer 112b.

[0310] The semiconductor layer 108 preferably contains the impurity element described above at least in the region in contact with the top surface of the conductive layer 112a and the region in contact with the top surface of the conductive layer 112b. Figure 9B and Figure 9C An example is shown in which the low-resistance region 108n is provided in the region in contact with the top surface of the conductive layer 112a and the region in contact with the top surface of the conductive layer 112b. Further, the low-resistance region 108n can also be provided in the region in contact with the side surface of the conductive layer 112b.

[0311] [Transistor 100H]

[0312] Figure 10A ​​A cross-sectional view of the transistor 100H is shown.

[0313] The transistor 100H is different from the transistor 100A in that the conductive layer 103 is included over the insulating layer 110b and the insulating layer 110f is included over the conductive layer 103.

[0314] The conductive layer 103 is positioned over the insulating layer 110b. The conductive layer 112a and the conductive layer 103 are electrically insulated from each other by the insulating layer 110a and the insulating layer 110b. The conductive layer 103 is provided with an opening portion at a position overlapping with the conductive layer 112a.

[0315] There is no limitation on the top surface shape of the opening portion provided in the conductive layer 103. Note that the top surface shape of the opening portion is the shape of a top surface end portion or a bottom surface end portion of the opening portion side of the conductive layer 103.

[0316] The insulating layer 110 includes the insulating layer 110a over the conductive layer 112a, the insulating layer 110b over the insulating layer 110a, the insulating layer 110f over the insulating layer 110b and the conductive layer 103, the insulating layer 110c over the insulating layer 110f, the insulating layer 110d over the insulating layer 110c, and the insulating layer 110e over the insulating layer 110d.

[0317] The insulating layer 110f covers the top surface and the side surface of the conductive layer 103. The insulating layer 110f is provided so as to cover part of the opening portion. The insulating layer 110f is in contact with the insulating layer 110b through the opening portion.

[0318] The insulating layer 110f preferably uses the same structure as the insulating layers 110a, 110b, and 110d. Specifically, the insulating layer 110f preferably uses a film in which oxygen is less likely to diffuse. Furthermore, the insulating layer 110f preferably uses a film in which hydrogen is less likely to diffuse.

[0319] In the transistor 100H, the semiconductor layer 108 has a region overlapping with the conductive layer 104 with the insulating layer 106 interposed therebetween and overlapping with the conductive layer 103 with part of the insulating layer 110 (particularly, the insulating layer 110f and the insulating layer 110c) interposed therebetween. In other words, the semiconductor layer 108 has a region sandwiched by the conductive layer 104 and the conductive layer 103 with the insulating layer 106 and part of the insulating layer 110 (particularly, the insulating layer 110f and the insulating layer 110c) interposed therebetween.

[0320] The conductive layer 103 is used as a back gate electrode (which can be referred to as a second gate electrode) of the transistor 100H. In addition, part of the insulating layer 110 is used as a back gate insulating layer (which can be referred to as a second gate insulating layer) of the transistor 100H.

[0321] By providing the back gate electrode in the transistor 100H, the potential of the back gate side (also referred to as a back channel) of the semiconductor layer 108 can be fixed, and the saturation property in the Id-Vd characteristics of the transistor 100H can be improved.

[0322] In this specification and the like, a case where the current change in the saturation region in the Id-Vd characteristics of a transistor is small (the inclination is small) is expressed as "the saturation property is high".

[0323] Further, since the transistor 100H has the back gate electrode, the back channel potential of the semiconductor layer 108 can be fixed, and a negative shift of the threshold voltage can be suppressed. Thus, a transistor which is normally off (i.e., the threshold voltage is positive) can be implemented.

[0324] Figure 10A An example in which the thickness of the insulating layer 110b is uniform in any portion is shown. Note that the thickness of the insulating layer 110b is sometimes different between a region overlapping with the conductive layer 103 and a region not overlapping with the conductive layer 103. For example, when a film is processed into the conductive layer 103, part of the region of the insulating layer 110b which does not overlap with the conductive layer 103 is sometimes removed, and the thickness thereof is reduced.

[0325] The semiconductor layer 108 preferably contains the impurity element described above at least in a region in contact with the top surface of the conductive layer 112a and a region in contact with the top surface of the conductive layer 112b. Figure 10A An example in which the low-resistance region 108n is provided in the region in contact with the top surface of the conductive layer 112a and the region in contact with the top surface of the conductive layer 112b is shown. Further, the low-resistance region 108n can also be provided in a region in contact with the side surface of the conductive layer 112b.

[0326] In the semiconductor layer 108, a region in contact with the conductive layer 112a is used as one of a source region and a drain region, and a region in contact with the conductive layer 112b is used as the other of the source region and the drain region. Further, in the semiconductor layer 108, a region in contact with the insulating layer 110a and a region in contact with the insulating layer 110e are used as low-resistance regions, and a region in contact with the insulating layer 110c is used as a channel formation region. In the description of this embodiment, a region in contact with the insulating layer 110f in the semiconductor layer 108 is not included in the channel formation region, but the region can be included in the channel formation region.

[0327] In Figure 10A The channel length L100 of the transistor 100H is indicated by a double-headed arrow in a dashed line in FIG. 1B. The channel length L100 can be said to be the shortest distance between a portion in the semiconductor layer 108 in contact with the insulating layer 110f and a portion in the semiconductor layer 108 in contact with the insulating layer 110d when viewed in cross section.

[0328] Generally speaking, when the channel length is small, the saturation in the Id-Vd characteristics of a transistor tends to decrease, but because the transistor 100H includes a back gate, high saturation can be achieved.

[0329] The preferred numerical ranges for channel length L100, thickness T110, and angle θ110 are as described above.

[0330] The thickness T3 of the conductive layer 103 is preferably 0.5 times or more the channel length L100, more preferably 1.0 times or more, and even more preferably more than 1.0 times. This expands the area in the semiconductor layer 108 where it overlaps with the conductive layer 104 separated by the insulating layer 106 and with the conductive layer 103 separated by the insulating layer 110. Therefore, the electric field of the back channel of the semiconductor layer 108 can be controlled more reliably.

[0331] Transistor 100H includes a region in which a conductive layer 103, an insulating layer 110, a semiconductor layer 108, an insulating layer 106, and a conductive layer 104 are sequentially stacked in one direction, without other layers in between. This direction can be exemplified by a direction perpendicular to the channel length L100. By expanding this region, the electric field of the back channel of the semiconductor layer 108 can be more reliably controlled.

[0332] The shortest distance L1 between the conductive layer 103 and the semiconductor layer 108 is preferably smaller than the channel length L100, more preferably 0.5 times or less, and even more preferably 0.1 times or less. The closer the conductive layer 103 is to the semiconductor layer 108, the better the saturation in the Id-Vd characteristics of the transistor 100H can be improved.

[0333] Note that, when viewed in cross-section, the shortest distance between the conductive layer 103 and the semiconductor layer 108 may differ on the left and right sides of the opening (opening 141) of the insulating layer 110. In this case, the distance L1 of at least one of the left and right sides of the opening preferably satisfies the above-described condition, and more preferably, the distance L1 of both sides satisfies the above-described condition. In any cross-section, the shortest distance between the conductive layer 103 and the semiconductor layer 108 on the left side of the opening is preferably 50% or more and 150% or less of the shortest distance on the right side of the opening, more preferably 30% or more and 130% or less, and even more preferably 10% or more and 110% or less.

[0334] like Figure 10A As shown, the channel length L100 is sometimes affected by the thickness T103 of the conductive layer 103, depending on the shortest distance L1 between the conductive layer 103 and the semiconductor layer 108.

[0335] The channel length L100 of the transistor corresponds to the length of the side of the opening portion 141 of the insulating layer 110c when seen from the cross section. When the distance between the conductive layer 103 and the semiconductor layer 108 is close (i.e., the distance L1 is made short), the channel length L100 is sometimes elongated due to the thickness of the conductive layer 103. Thus, the channel length L100 can be more than one time, more than 1.5 times, or more than 2 times the thickness T110.

[0336] The conductive layer 103 can have a single-layer structure or a stacked-layer structure of two or more layers. The conductive layer 103 can use a material that can be used for the conductive layer 112a, the conductive layer 112b, and the conductive layer 104.

[0337] Alternatively, the conductive layer 103 can be provided in contact with the conductive layer 112a and the insulating layer 110 can be provided over the conductive layer 103. In this case, the conductive layer 103 can be used as auxiliary wiring of the conductive layer 112a in addition to being used as a back gate electrode.

[0338] In this case, the conductive layer 103 preferably uses a material having higher conductivity than the conductive layer 112a. By this means, the conductive layer 103 can be effectively used as auxiliary wiring of the conductive layer 112a. As the conductive layer 103, one or a plurality of elements selected from copper, aluminum, titanium, tungsten, and molybdenum, or an alloy containing one or a plurality of the above elements can be used as appropriate.

[0339] The conductive layer 103 and the conductive layer 112a in contact with each other are supplied with the same potential. The conductive layer 103 used as a back gate electrode is preferably supplied with a potential on the low potential side between a source potential and a drain potential. In the case where the transistor is an n-channel transistor, it is preferable that the conductive layer 112a be used as a source electrode and the conductive layer 112b be used as a drain electrode. In the case where the transistor is a p-channel transistor, it is preferable that the conductive layer 112a be used as a drain electrode and the conductive layer 112b be used as a source electrode.

[0340] [Transistor 100I]

[0341] Figure 10B A cross-sectional view of the transistor 100I is shown.

[0342] The transistor 100I differs from the transistor 100H mainly in that the insulating layer 110 has a stacked-layer structure of eight layers.

[0343] The insulating layer 110 includes an insulating layer 110a on the conductive layer 112a, an insulating layer 110b on the insulating layer 110a, an insulating layer 110c1 on the insulating layer 110b, an insulating layer 110f1 on the insulating layer 110c1, an insulating layer 110f2 on the conductive layer 103, an insulating layer 110c2 on the insulating layer 110f2, an insulating layer 110d on the insulating layer 110c2, and an insulating layer 110e on the insulating layer 110d.

[0344] Both insulating layers 110c1 and 110c2 can use the same structure as that used for insulating layer 110c. Specifically, both insulating layers 110c1 and 110c2 preferably use oxygen-containing layers, and preferably include regions with a higher oxygen content compared to at least one of insulating layers 110a, 110b, 110d, 110e, 110f1, and 110f2.

[0345] Insulating layers 110f1 and 110f2 can use the same structure as that used for insulating layer 110f. Specifically, insulating layers 110f1 and 110f2 preferably use films that are not easily diffused by oxygen. Furthermore, insulating layers 110f1 and 110f2 preferably use films that are not easily diffused by hydrogen.

[0346] The above structure can be used for insulating layers 110a, 110b, 110d, and 110e.

[0347] exist Figure 10B In this context, the channel length L100 can be described as the shortest distance between the portion of the semiconductor layer 108 that contacts the insulating layer 110b and the portion that contacts the insulating layer 110d.

[0348] By adopting this structure, the insulating layer 110 can be a symmetrical structure between the upper and lower conductive layer 103. Furthermore, since oxygen can be supplied to the semiconductor layer 108 from both insulating layers 110c1 and 110c2, transistor characteristics can be improved.

[0349] One embodiment of the transistor in this invention is a vertical transistor, which allows for overlapping of the source electrode, semiconductor layer, and drain electrode, resulting in a significantly smaller footprint compared to planar transistors. Furthermore, by using a p-channel Si transistor as a planar transistor and an n-channel OS transistor as a vertical transistor, a CMOS (Complementary Metal Oxide Semiconductor) circuit can be constructed. Additionally, by employing this structure and overlapping the planar and vertical transistors, the footprint of the CMOS circuit can be reduced.

[0350] In addition, the vertical transistor can increase the on-state current and the degree of integration as compared with the planar transistor, so that the problem of the OS transistor in which the on-state current is lower than the LTPS can be solved, and a narrow frame of a display device can also be achieved. Thus, even without using a structure in which an LTPS transistor and an OS transistor are combined (also referred to as LTPO), a backplane of a display device can be implemented using only the OS transistor regardless of whether the size is large or small. When a display device is manufactured using only the OS transistor, the number of photomasks needed can be reduced, the number of manufacturing steps can be reduced, and thus cost reduction can be achieved as compared with the case of using the LTPO.

[0351] A transistor of one embodiment of the present application includes an impurity element in a source region and a drain electrode of a semiconductor layer. Thus, the sheet resistance of the semiconductor layer can be reduced. Further, the contact resistance between the source electrode or the drain electrode and the semiconductor layer can be reduced. Thus, the on-state current of the transistor can be increased.

[0352] This embodiment mode can be combined as appropriate with other embodiment modes. Furthermore, in this specification, in the case where a plurality of structure examples are shown in one embodiment mode, the structure examples can be combined as appropriate.

[0353] (Embodiment 2)

[0354] In this embodiment mode, a method for manufacturing a semiconductor device of one embodiment of the present application is described with reference to FIG. 11 to FIG. 14. In this embodiment mode, a method for manufacturing the transistor 100B described in Embodiment 1 is described. Note that the materials and the formation methods of the components are omitted in some cases where they are the same as those described in Embodiment 1.

[0355] FIG. 11 to FIG. 14 show cross-sectional views along the dot-dash line A1-A2 and the dot-dash line B1-B2 in FIG. 10. Figure 1A

[0356] The thin films (insulating films, semiconductor films, and conductive films) included in the semiconductor device can be formed by a sputtering method, a CVD method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an ALD method, or the like. As the CVD method, a PECVD method, a thermal CVD method, or the like is used. As one of the thermal CVD methods, a metal organic CVD (MOCVD) method is used.

[0357] The thin films (insulating films, semiconductor films, and conductive films) included in the semiconductor device can be formed by a wet deposition method such as a spin coating method, an immersion method, a spray coating method, an inkjet method, a dispenser method, a screen printing method, an offset printing method, a doctor knife method, a slit coater method, a roll coater method, a curtain coater method, or a blade coater method.​

[0358] Further, when the thin film constituting the semiconductor device is processed, photolithography or the like can be used. Alternatively, the thin film can be processed by nanoimprint, sandblasting, peeling, or the like. Further, the thin film can be formed in an island shape by a deposition method using a metal mask or the like as a mask.

[0359] Photolithography typically has two methods. One is a method in which a resist mask is formed on a thin film to be processed, the thin film is processed by etching or the like, and the resist mask is removed. The other is a method in which a thin film having photosensitivity is deposited, and then exposed and developed, and the thin film is processed into a desired shape.

[0360] In photolithography, as light for exposure, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or light in which these lights are mixed can be used, for example. Further, ultraviolet light, KrF laser light, or ArF laser light, or the like can be used. Further, exposure can be performed by liquid immersion exposure technology. Further, as light for exposure, extreme ultraviolet (EUV) light or X-ray can be used. Further, instead of light for exposure, an electron beam can be used. When extreme ultraviolet light, X-ray, or an electron beam is used, extremely fine processing can be performed, and thus is preferable. Note that when exposure is performed by scanning with a light beam such as an electron beam, a photomask is not needed.

[0361] As a method for etching the thin film, dry etching, wet etching, sandblasting, or the like can be used.

[0362] First, the insulating layer 109 is formed over the substrate 102, and the conductive layer 112a (112b) is formed over the insulating layer 109. Figure 11A ).

[0363] The insulating layer 109 includes a region in which the hydrogen content is higher than that of the insulating layer 110b to be formed later.

[0364] The proportion of the flow rate of NH3 gas in the deposition gas of the insulating layer 109 is preferably higher than that of the insulating film 110bf to be deposited later. The deposition gas of the insulating film 110bf can not use NH3 gas. By deposition under conditions in which the proportion of the flow rate of NH3 gas with respect to the total flow rate of the deposition gas is high, the hydrogen content of the insulating layer 109 can be increased. Thus, the amount of hydrogen released by heating in the insulating layer 109 can be increased. In addition, the amount of hydrogen released by heating in the insulating layer 110b can be reduced.

[0365] Furthermore, by differentiating the deposition conditions of the insulating layer 109 and the insulating film 110bf, the amount of hydrogen released through heating in the insulating layer 109 can be adjusted. Specifically, in the deposition conditions of the insulating layer 109 and the insulating film 110bf, one or more of the following can be differed: deposition power (deposition power density), deposition pressure, type of deposition gas, deposition gas flow ratio, deposition temperature, and distance between the substrate and the electrode. For example, by making the deposition power density of the insulating layer 109 lower than that of the insulating film 110bf, the hydrogen content in the insulating layer 109 can be made higher than that in the insulating film 110bf. This increases the amount of hydrogen released through heating in the insulating layer 109.

[0366] For example, silicon nitride film is preferably formed as insulating layer 109.

[0367] The insulating layer 109 is preferably formed, for example, by sputtering or PECVD. In particular, PECVD is preferred because it allows for the easy formation of both low-hydrogen-content and high-hydrogen-content films.

[0368] The substrate temperature for forming the insulating layer 109 is preferably 180°C or higher and 450°C or lower, more preferably 200°C or higher and 450°C or lower. Furthermore, the substrate temperature for forming the insulating layer 109 is preferably lower than the substrate temperature for forming the insulating film 110bf. This increases the amount of hydrogen released through heating.

[0369] Note that the insulating layer 109 is formed before the semiconductor layer 108 is formed, so there is no need to worry about oxygen being removed from the semiconductor layer 108 due to the heat applied when the insulating layer 109 is formed.

[0370] In addition, in manufacturing Figure 5A and Figure 5B In the case of transistor 100A shown, insulating layer 109 is not provided, and insulating layer 110a is formed as the first layer of insulating layer 110. Insulating layer 110a is preferably formed using the method for forming insulating layer 109 described above.

[0371] The conductive layer 112a can be formed by forming a conductive film that becomes the conductive layer 112a and processing it. When forming the conductive film that becomes the conductive layer 112a, sputtering is preferably used, for example. After forming a photoresist mask on the conductive film using a photolithography process, the conductive film is processed, thereby forming the conductive layer. One or both of wet etching and dry etching methods can be used in the processing of the conductive film.

[0372] Note that in the case where the conductive layer 112a has a stacked-layer structure of two or more layers, the plurality of layers formed so as to have a top surface shape that is the same or substantially the same can be processed using the same mask pattern. Alternatively, each layer included in the conductive layer 112a can be processed using different mask patterns.

[0373] Next, the insulating film 110bf which becomes the insulating layer 110b and the insulating film 110cf which becomes the insulating layer 110c are formed over the conductive layer 112a. Figure 11B

[0374] For example, a silicon nitride film or an aluminum oxide film is preferably formed as the insulating film 110bf. Further, for example, a silicon oxide film or a silicon oxynitride film is preferably formed as the insulating film 110cf.

[0375] In forming the insulating film 110bf and the insulating film 110cf, for example, a sputtering method or a PECVD method is preferably used. In particular, by using the PECVD method, both a film with low hydrogen content and a film with high hydrogen content can be easily formed, and thus the PECVD method is preferable. It is preferable that the insulating film 110cf be continuously formed in a vacuum after the insulating film 110bf is formed, without exposing the surface of the insulating film 110bf to the atmosphere. By continuously forming the insulating film 110bf and the insulating film 110cf, attachment of impurities from the atmosphere to the surface of the insulating film 110bf can be suppressed. As the impurities, for example, water and an organic substance can be given.

[0376] The substrate temperature at the time of forming the insulating film 110bf and the insulating film 110cf is preferably higher than or equal to 180 °C and lower than or equal to 450 °C, more preferably higher than or equal to 200 °C and lower than or equal to 450 °C, further more preferably higher than or equal to 250 °C and lower than or equal to 450 °C, still further more preferably higher than or equal to 300 °C and lower than or equal to 450 °C, yet further more preferably higher than or equal to 300 °C and lower than or equal to 400 °C, and even further more preferably higher than or equal to 350 °C and lower than or equal to 400 °C. By setting the substrate temperature at the time of forming the insulating film 110bf and the insulating film 110cf to be within the above range, release of impurities (e.g., water and hydrogen) from the insulating film 110bf and the insulating film 110cf themselves can be reduced, and thus diffusion of the impurities into the semiconductor layer 108 can be suppressed. Thus, a transistor which has favorable electrical characteristics and high reliability can be realized.

[0377] Note that since the insulating film 110bf and the insulating film 110cf are formed first and then the semiconductor layer 108 is formed, there is no concern that oxygen is released from the semiconductor layer 108 due to heat applied at the time of forming the insulating film 110bf and the insulating film 110cf.

[0378] ​It is preferable to perform plasma treatment in an oxygen-containing atmosphere after forming the insulating film 110cf without being opened to the atmosphere (in-situ). For example, it is preferable to perform N2O plasma treatment. By performing such plasma treatment, oxygen can be supplied to the insulating film 110cf.

[0379] Next, a metal oxide layer 149 is formed over the insulating film 110cf. Figure 11C By forming the metal oxide layer 149, oxygen can be supplied to the insulating film 110cf.

[0380] There is no limitation on the conductivity of the metal oxide layer 149. The metal oxide layer 149 can use at least one of an insulating film, a semiconductor film, and a conductive film. The metal oxide layer 149 can use, for example, aluminum oxide, hafnium oxide, hafnium aluminate, indium oxide, indium tin oxide (ITO), or indium tin silicon oxide (ITSO).

[0381] As the metal oxide layer 149, it is preferable to use an oxide material containing one or more elements which are the same as those of the semiconductor layer 108. In particular, it is preferable to use an oxide semiconductor material which can be applied to the semiconductor layer 108.

[0382] When the metal oxide layer 149 is formed, the higher the ratio of the oxygen flow rate to the total flow rate of the deposition gas introduced into the treatment chamber of the deposition apparatus (oxygen flow rate ratio) or the oxygen partial pressure in the treatment chamber, the more the amount of oxygen supplied to the insulating film 110cf can be increased. The oxygen flow rate ratio or the oxygen partial pressure is, for example, 50 % or more and 100 % or less, preferably 65 % or more and 100 % or less, more preferably 80 % or more and 100 % or less, and further preferably 90 % or more and 100 % or less. In particular, it is preferable to set the oxygen flow rate ratio to 100 % so that the oxygen partial pressure is as close to 100 % as possible.

[0383] Thus, by forming the metal oxide layer 149 using a sputtering method in an oxygen-containing atmosphere, oxygen can be supplied to the insulating film 110cf while preventing oxygen from being released from the insulating film 110cf at the time of forming the metal oxide layer 149. As a result, more oxygen can be enclosed in the insulating film 110cf. Further, more oxygen can be supplied to the semiconductor layer 108 by a subsequent heat treatment. As a result, the oxygen vacancy and V O H, and a transistor which exhibits good electrical characteristics and has high reliability can be implemented.

[0384] It is preferable to perform a heat treatment after forming the metal oxide layer 149. By performing a heat treatment after forming the metal oxide layer 149, oxygen can be effectively supplied to the insulating film 110cf from the metal oxide layer 149.

[0385] The temperature of the heat treatment is preferably higher than or equal to 150 °C and lower than the strain point of the substrate, more preferably higher than or equal to 200 °C and lower than 450 °C, still more preferably higher than or equal to 250 °C and lower than 450 °C, yet more preferably higher than or equal to 300 °C and lower than 450 °C, further more preferably higher than or equal to 300 °C and lower than 400 °C, and even further more preferably higher than or equal to 350 °C and lower than 400 °C. The heat treatment can be performed in an atmosphere containing one or more of a noble gas, nitrogen, and oxygen. As the nitrogen atmosphere or the oxygen atmosphere, dry air (CDA: Clean Dry Air) can be used. Note that the content of hydrogen, oxygen, or the like in the atmosphere is preferably as low as possible. As the atmosphere, a high-purity gas whose dew point is -60 °C or lower, preferably -100 °C or lower, is preferably used. By using an atmosphere whose content of hydrogen, water, or the like is as low as possible, absorption of hydrogen, water, or the like into the insulating film 110cf or the like can be prevented as much as possible. The heat treatment can be performed using an oven, an RTA (Rapid Thermal Annealing) apparatus, or the like. By using an RTA apparatus, the heat treatment time can be shortened.

[0386] Oxygen can also be supplied to the insulating film 110cf through the metal oxide layer 149 after the formation of the metal oxide layer 149 or after the above heat treatment. As a method for supplying oxygen, an ion implantation method, an ion doping method, a plasma immersion ion implantation method, or a plasma treatment can be used, for example. In the plasma treatment in the method for manufacturing a semiconductor device of one embodiment of the present application, an apparatus for plasma-izing oxygen gas with high-frequency power can be used as appropriate. As an apparatus for plasma-izing a gas with high-frequency power, a plasma etching apparatus and a plasma ashing apparatus can be given, for example.

[0387] Note that heat treatment can also be performed after the formation of the insulating film 110cf and before the formation of the metal oxide layer 149. By performing heat treatment, water and hydrogen can be released from the surface and the film of the insulating film 110cf.

[0388] Next, the metal oxide layer 149 is removed (see FIG. 1C). Figure 11D ).

[0389] Although there is no particular limitation on the method for removing the metal oxide layer 149, a wet etching method can be used as appropriate. By using a wet etching method, the insulating film 110cf can be prevented from being etched when the metal oxide layer 149 is removed. Thus, the thickness of the insulating film 110cf can be prevented from being reduced, and the thickness of the insulating layer 110c can be made uniform.

[0390] Note that the oxygen supply treatment on the insulating film 110cf is not limited to the above method. For example, an ion doping method, an ion implantation method, or plasma treatment can be used to supply oxygen radicals, oxygen atoms, oxygen atom ions, or oxygen molecule ions to the insulating film 110cf. Alternatively, a film for suppressing separation of oxygen can be formed over the insulating film 110cf, and oxygen can be supplied to the insulating film 110cf through the film. The film is preferably removed after the oxygen supply. As the film for suppressing separation of oxygen, a conductive film or a semiconductor film containing one or more of indium, zinc, gallium, tin, aluminum, chromium, tantalum, titanium, molybdenum, nickel, iron, cobalt, and tungsten can be used.

[0391] Next, an insulating film 110df which becomes the insulating layer 110d and an insulating film 110ef which becomes the insulating layer 110e are formed over the insulating film 110cf. Figure 11D

[0392] As described above, the insulating layer 110e includes a region with a higher hydrogen content than the insulating layer 110d.

[0393] The proportion of the flow rate of NH3gas in the deposition gas of the insulating film 110ef is preferably higher than that of the deposition gas of the insulating film 110df. The deposition gas of the insulating film 110df can not contain NH3gas. By deposition under conditions where the proportion of the flow rate of NH3gas to the total flow rate of the deposition gas is high, the hydrogen content in the insulating film 110ef can be increased. Thus, the amount of hydrogen released by heating in the insulating layer 110e can be increased. Further, the amount of hydrogen released by heating in the insulating layer 110d can be reduced.

[0394] Further, by making the deposition conditions of the insulating film 110ef and the insulating film 110df different, the amount of hydrogen released by heating in the insulating layer 110e can be adjusted. Specifically, one or more of the deposition power (deposition power density), the deposition pressure, the kind of deposition gas, the proportion of the flow rate of the deposition gas, the deposition temperature, and the distance between the substrate and the electrode are made different between the deposition conditions of the insulating film 110ef and the insulating film 110df. For example, when the deposition power density of the insulating film 110ef is lower than that of the insulating film 110df, the hydrogen content of the insulating film 110ef can be made higher than that of the insulating film 110df. Thus, the amount of hydrogen released by heating in the insulating layer 110e can be increased.

[0395] For example, as the insulating films 110df and 110ef, a silicon nitride film is preferably formed. Alternatively, as the insulating film 110df, a silicon oxide film is preferably formed, and as the insulating film 110ef, a silicon nitride film is preferably formed.

[0396] ​The other portions in the formation of the insulating film 110df can be described with reference to the formation of the insulating film 110bf. Note that the deposition conditions of the insulating film 110bf and the insulating film 110df can be the same or different.

[0397] Similarly, the formation of the insulating film 110ef can be described with reference to the formation of the insulating layer 109. Note that the deposition conditions of the insulating layer 109 and the insulating film 110ef can be the same or different.

[0398] Next, a conductive film 112f which becomes the conductive layer 112b is formed over the insulating film 110ef and is processed, whereby the conductive layer 112b having the opening portion 143 is formed. Figures 12A to 12C ).

[0399] In this embodiment mode, an example is shown in which the conductive film 112f is formed as shown in FIG. 17A, is processed into a conductive layer 112B in an island shape or the like as desired as shown in FIG. 17B, and then the conductive layer 112B is opened as shown in FIG. 17C, whereby the conductive layer 112b having the opening portion 143 is formed. Alternatively, the conductive film 112f can be processed into the conductive layer 112b having the opening portion 143 after being opened. Figure 12A Figure 12B Figure 12C The conductive layer 112b is formed so as to have the opening portion 143 at a position overlapping with a portion to be opened later in the insulating film 110bf, 110cf, 110df, or 110ef.

[0400] Next, the insulating film 110bf to the insulating film 110ef are opened, and the insulating layer 110 (the insulating layer 110b, 110c, 110d, 110e) having the opening portion 141 is formed. Figure 12C ).

[0401] The opening portion 141 is provided at a position overlapping with the opening portion 143 of the conductive layer 112b. By providing the opening portion 141, a region of the conductive layer 112a overlapping with the opening portions 141 and 143 is exposed.

[0402] In processing the conductive film 112f (which can be said to be forming the conductive layer 112B and forming the conductive layer 112b), one or both of a wet etching method and a dry etching method can be used. In particular, it is preferable to form the opening portion 143 using a wet etching method.

[0403] In forming the opening portion 141, one or both of a wet etching method and a dry etching method can be used, and for example, a dry etching method is preferably used.

[0404] ​​The opening portion 141 can be formed, for example, using a resist mask used to form the opening portion 143. Specifically, a resist mask can be formed on the conductive layer 112B and used to remove a portion of the conductive layer 112B to form the opening portion 143, and the resist mask can be used to remove a portion of each of the insulating films 110bf, 110cf, 110df, 110ef to form the opening portion 141. Alternatively, the opening portion 141 and the opening portion 143 can be formed using different resist masks, respectively.

[0405] Next, a metal oxide film 108f that becomes the semiconductor layer 108 is formed so as to cover the opening portion 141 and the opening portion 143. Figure 13A The metal oxide film 108f is provided so as to be in contact with the top surface and the side surface of the conductive layer 112b, the top surface and the side surface of the insulating layer 110, and the top surface of the conductive layer 112a.

[0406] The metal oxide film 108f is preferably formed so as to have a uniform thickness as much as possible on the side surface in the opening portion 141 of the insulating layer 110 and the side surface in the opening portion 143 of the conductive layer 112b. The metal oxide film 108f can be deposited, for example, by a sputtering method or an ALD method.

[0407] The metal oxide film 108f is preferably formed by a sputtering method using a metal oxide target.

[0408] The metal oxide film 108f is preferably a dense film in which defects are as few as possible. The metal oxide film 108f is preferably a film in which impurities of hydrogen elements are as low as possible. In particular, as the metal oxide film 108f, a metal oxide film having crystallinity is preferably used.

[0409] When the metal oxide film 108f is formed, an oxygen gas is preferably used. By using the oxygen gas when the metal oxide film 108f is formed, oxygen can be appropriately supplied to the insulating layer 110. For example, when the insulating layer 110c is an oxide, oxygen can be appropriately supplied to the insulating layer 110c.

[0410] By supplying oxygen to the insulating layer 110c, oxygen can be supplied to the semiconductor layer 108 in a later process, and thus oxygen vacancies and V O H.

[0411] When depositing the metal oxide film 108f, an oxygen gas and an inert gas (e.g., a helium gas, an argon gas, a xenon gas, or the like) can be mixed. Note that the higher the proportion of the flow rate of the oxygen gas to the total flow rate of the deposition gas (oxygen flow rate ratio) when depositing the metal oxide film 108f, the higher the crystallinity of the metal oxide film 108f can be, and a transistor with high reliability can be achieved. On the other hand, the lower the oxygen flow rate ratio, the lower the crystallinity of the metal oxide film 108f can be, and a transistor with a large on-state current can be achieved.

[0412] When the substrate temperature is high at the time of forming the metal oxide film 108f, a metal oxide film with higher crystallinity and higher density can be formed. On the other hand, when the substrate temperature is low, a metal oxide film 108f with lower crystallinity and higher conductivity can be formed.

[0413] The substrate temperature at the time of forming the metal oxide film 108f is preferably higher than or equal to room temperature and lower than or equal to 250 °C, more preferably higher than or equal to room temperature and lower than or equal to 200 °C, and further preferably higher than or equal to room temperature and lower than or equal to 140 °C. For example, the substrate temperature is preferably higher than or equal to room temperature and lower than or equal to 140 °C, whereby productivity can be improved. By depositing the metal oxide film 108f at a substrate temperature of room temperature or without heating the substrate, the crystallinity can be reduced.

[0414] When the ALD method is used, a deposition method such as a thermal ALD method or a PEALD (Plasma Enhanced ALD) method is preferably used. The thermal ALD method has extremely high step coverage and is thus preferable. Further, the PEALD method has high step coverage and enables low-temperature deposition, and is thus preferable.

[0415] The metal oxide film 108f can be deposited, for example, by using a precursor containing a metal element and an oxidizing agent and by using the ALD method.

[0416] As the precursor containing indium, for example, trimethylindium, triethylindium, tris(2,2,6,6-tetramethyl-3,5-heptanedionate)indium, indium cyclopentadienyl, indium (III) chloride, and (3-(dimethylamino)propyl)dimethylindium can be given.

[0417] As the precursor containing gallium, for example, trimethylgallium, triethylgallium, tris(dimethylamide)gallium (III), gallium (III) acetylacetonate, tris(2,2,6,6-tetramethyl-3,5-heptanedionate)gallium, dimethylchlorogallium, diethylchlorogallium, and gallium (III) chloride can be given.

[0418] As the precursor containing tin, for example, tetramethyltin, tetraethyltin, tetravinyltin, tetraallyltin, tributylvinyltin, allyltributyltin, tributylethyltin, tributylphenyltin, trimethyltin chloride, triethyltin chloride, and tin (IV) chloride can be given.

[0419] As the precursor containing zinc, for example, dimethylzinc, diethylzinc, bis (2, 2, 6, 6-tetramethyl-3, 5-heptanedionate) zinc, and zinc chloride can be given.

[0420] For example, when an In-Ga-Zn oxide is deposited, three kinds of precursors, a precursor containing indium, a precursor containing gallium, and a precursor containing zinc can be used. Alternatively, two kinds of precursors, a precursor containing indium, and a precursor containing gallium and zinc can be used.

[0421] As the oxidizing agent, for example, ozone, oxygen, and water can be given.

[0422] As a method of controlling the composition of the obtained film, adjustment of the flow rate ratio of the source gases, the flow time of the source gases, the flow order of the source gases, and the like can be given. Further, by adjusting them, a film whose composition continuously changes can be deposited. Further, films whose compositions are different can be continuously deposited.

[0423] Before the deposition of the metal oxide film 108f, at least one of a treatment for removing water, hydrogen, and organic substances, and the like adsorbed on the surface of the insulating layer 110 and a treatment for supplying oxygen to the insulating layer 110 is preferably performed. For example, heat treatment can be performed at a temperature higher than or equal to 70 °C and lower than or equal to 200 °C in a reduced pressure atmosphere. Alternatively, plasma treatment in an oxygen-containing atmosphere can be performed. Alternatively, by performing plasma treatment in an atmosphere containing an oxidizing gas such as nitrous oxide (N2O), oxygen can be supplied to the insulating layer 110. When plasma treatment including nitrous oxide gas is performed, organic substances on the surface of the insulating layer 110 can be appropriately removed and oxygen can be supplied to the insulating layer 110. It is preferable that, after such a treatment, the metal oxide film 108f be continuously deposited in such a manner that the surface of the insulating layer 110 is not exposed to the air.

[0424] Note that in the case where the semiconductor layer 108 has a stacked structure, it is preferable that, after the deposition of a lower metal oxide film, an upper metal oxide film be continuously deposited in such a manner that the surface thereof is not exposed to the air.

[0425] Further, in the case where the semiconductor layer 108 has a stacked-layer structure, all of the layers constituting the semiconductor layer 108 can be formed by the same deposition method (e.g., a sputtering method or an ALD method), or different deposition methods can be used for each layer. For example, the first metal oxide film can be deposited by a sputtering method and the second metal oxide film can be deposited by an ALD method.

[0426] Next, the metal oxide film 108f is processed into an island shape, and the semiconductor layer 108 Figure 13B ) is formed.

[0427] The semiconductor layer 108 can be formed by one or both of a wet etching method and a dry etching method, and for example, a wet etching method is preferably used. At this time, a portion of the conductive layer 112b in a region not overlapping with the semiconductor layer 108 is sometimes etched and becomes thinner. Similarly, a portion of the insulating layer 110 in a region not overlapping with both the semiconductor layer 108 and the conductive layer 112b is sometimes etched and becomes thinner. For example, the insulating layer 110e in the insulating layer 110 is sometimes removed by etching, and the surface of the insulating layer 110d is exposed. Note that in etching of the metal oxide film 108f, by using a material with a high selection ratio for the insulating layer 110e, the thickness of the insulating layer 110e can be prevented from becoming small.

[0428] A heat treatment is preferably performed after deposition of the metal oxide film 108f or after processing of the metal oxide film 108f into the semiconductor layer 108. By the heat treatment, hydrogen or water contained in the metal oxide film 108f or the semiconductor layer 108 or adsorbed on the surface of the metal oxide film 108f or the semiconductor layer 108 can be removed. Further, by the heat treatment, the film quality of the metal oxide film 108f or the semiconductor layer 108 is sometimes improved (e.g., reduction of defects or improvement of crystallinity, or the like). The heat treatment is preferably performed before processing of the semiconductor layer 108.

[0429] Oxygen is preferably supplied to at least a portion of the metal oxide film 108f or at least a portion of the semiconductor layer 108 by the heat treatment. The region of the semiconductor layer 108 in contact with the insulating layer 110c and its vicinity is used as a channel formation region. By supplying oxygen to this region, oxygen vacancies in the channel formation region can be reduced, and the carrier concentration can be lowered. That is, the channel formation region can be made an i-type (intrinsic) or substantially i-type region. Thus, a transistor with stable electrical characteristics can be obtained.

[0430] Further, it is preferable that hydrogen be supplied to part of the metal oxide film 108f or part of the semiconductor layer 108 from the insulating layer 109 through the conductive layer 112a by heat treatment. By supplying hydrogen to the region of the semiconductor layer 108 in contact with the conductive layer 112a and its vicinity, the region can be made low in resistance. Thus, the contact resistance between the conductive layer 112a and the semiconductor layer 108 can be reduced. Further, the on-state current of the transistor can be increased.

[0431] The heat treatment can be performed as described above, and thus detailed description is omitted.

[0432] Note that the heat treatment is not necessarily performed. The heat treatment performed in a later step can be used as the heat treatment in this step without performing the heat treatment in this step. In some cases, a process at high temperature (e.g., a deposition step) in a later step can be used as the heat treatment in this step.

[0433] Next, an insulating layer 106 is formed so as to cover the semiconductor layer 108, the conductive layer 112b, and the insulating layer 110. Figure 13B The insulating layer 106 is preferably formed by a PECVD method or an ALD method, for example.

[0434] When the semiconductor layer 108 is an oxide semiconductor, the insulating layer 106 is preferably used as a barrier film against diffusion of oxygen. By giving the insulating layer 106 a function of inhibiting diffusion of oxygen, diffusion of oxygen from the upper side of the insulating layer 106 to the conductive layer 104 and oxidation of the conductive layer 104 can be inhibited. As a result, a transistor with favorable electrical characteristics and high reliability can be implemented.

[0435] Note that a barrier film in this specification and the like means a film having barrier properties. For example, an insulating layer having barrier properties can be referred to as a barrier insulating layer. In this specification and the like, barrier properties mean one or both of a function of inhibiting diffusion of a corresponding substance (which can be said to be low in permeability) and a function of trapping or fixing (also referred to as gettering) a corresponding substance.

[0436] By increasing the temperature at the time of formation of the insulating layer 106 serving as a gate insulating layer, an insulating layer with few defects can be formed. However, when the temperature at the time of formation of the insulating layer 106 is high, oxygen is released from the semiconductor layer 108, and in some cases, oxygen vacancies and V OH is increased. The substrate temperature at the time of forming the insulating layer 106 is preferably higher than or equal to 180 °C and lower than or equal to 450 °C, further preferably higher than or equal to 200 °C and lower than or equal to 450 °C, still further preferably higher than or equal to 250 °C and lower than or equal to 450 °C, yet further preferably higher than or equal to 300 °C and lower than or equal to 450 °C, and particularly preferably higher than or equal to 300 °C and lower than or equal to 400 °C. By setting the substrate temperature at the time of forming the insulating layer 106 to be within the above range, oxygen can be prevented from being released from the semiconductor layer 108 while reducing defects in the insulating layer 106. Thus, a transistor with high reliability which has good electrical characteristics can be obtained.

[0437] The surface of the semiconductor layer 108 can also be subjected to plasma treatment before the insulating layer 106 is formed. By the plasma treatment, impurities such as water adsorbed on the surface of the semiconductor layer 108 can be reduced. Thus, impurities in the interface between the semiconductor layer 108 and the insulating layer 106 can be reduced, and a transistor with high reliability can be obtained. In particular, in the case where the surface of the semiconductor layer 108 is exposed to the air between the formation of the semiconductor layer 108 and the formation of the insulating layer 106, it is preferable to perform plasma treatment. The plasma treatment can be performed, for example, in an atmosphere of oxygen, ozone, nitrogen, nitrous oxide, argon, or the like. The plasma treatment and the deposition of the insulating layer 106 are preferably continuously performed without exposure to the air.

[0438] Further, when a film containing a large amount of oxygen is used as the insulating layer 106, oxygen can be supplied from the insulating layer 106 to the semiconductor layer 108, and is thus preferable. Further, the insulating layer 106 is more preferably a film which releases oxygen by heating. By releasing oxygen from the insulating layer 106 due to heat applied in the manufacturing process of the transistor, oxygen can be supplied to the semiconductor layer 108. By supplying oxygen from the insulating layer 106 to the semiconductor layer 108, particularly to the channel formation region of the semiconductor layer 108, oxygen vacancies in the semiconductor layer 108 can be reduced, and a transistor with good electrical characteristics and high reliability can be obtained.

[0439] Next, an impurity element 189 (e.g., phosphorus) is added to the semiconductor layer 108 through the insulating layer 106 (see FIG. 1C). Figure 14A By adding the impurity element 189, the sheet resistance of the semiconductor layer 108, the contact resistance between the semiconductor layer 108 and the conductive layer 112a, and the contact resistance between the semiconductor layer 108 and the conductive layer 112b can be reduced.

[0440] As described above, impurity element 189 is preferably added from a direction perpendicular to or substantially perpendicular to the top surface of substrate 102. In this case, as mentioned above, in semiconductor layer 108, the amount of impurity element added to the surface inclined to the top surface of substrate 102 is less than that to the surface parallel to or substantially parallel to the top surface of substrate 102. In other words, the amount of impurity element added to the source and drain regions of semiconductor layer 108 is greater than that to the channel formation region. Therefore, the resistance of the source and drain regions can be preferentially reduced.

[0441] Furthermore, impurity element 189 is preferably added to semiconductor layer 108 via insulating layer 106. In this case, as described above, the thickness of insulating layer 106 in the direction in which impurity element 189 is added varies depending on the location. Therefore, regions with a high amount of impurity element 189 and regions with a low amount of impurity element 189 are formed in semiconductor layer 108. Specifically, regions in semiconductor layer 108 provided along the top surface of conductive layer 112a or the top surface of conductive layer 112b have a higher amount of impurity element added compared to regions provided along the side surface of insulating layer 110. In this way, impurity elements can be suppressed from entering the channel formation region of semiconductor layer 108, thereby preferentially reducing the resistance of source and drain regions. At this time, impurity element 189 is also supplied to insulating layer 106.

[0442] Figure 14A An example is shown in which a low-resistance region 108n is formed in a region disposed along the top surface of conductive layer 112a and a region disposed along the top surface of conductive layer 112b in semiconductor layer 108.

[0443] The elements that can be used as impurity element 189 are as described above.

[0444] Impurity element 189 can be supplied using plasma ion doping or ion implantation methods. By using these methods, the concentration distribution in the depth direction can be controlled with high precision based on factors such as ion acceleration voltage and dosage.

[0445] The purity of the supplied impurity element can be improved by using ion implantation, which involves mass separation of the ions by ionizing the source gas. When using ion implantation, the aforementioned first element is preferably used as impurity element 189, and boron or phosphorus is more preferably used. By using an element stabilized by bonding with oxygen as impurity element 189, a stable low-resistance region 108n can be achieved under low resistance conditions.

[0446] Furthermore, productivity can be improved by using plasma ion doping, which adds ions by ionizing the source gas without mass separation. When using plasma ion doping, the impurity element 189 is preferably a combination of the first element and hydrogen, more preferably a combination of boron or phosphorus and hydrogen. By using the combination of the element stabilized by bonding with oxygen and hydrogen as the impurity element 189, the resistance of the low-resistance region 108n can be easily reduced, and the low-resistance state can be stably maintained.

[0447] The ion implantation or ion doping equipment used to supply impurity element 189 is also used in the manufacture of Si transistors such as LTPS transistors. Therefore, it is preferred to use equipment from existing LTPS production lines without requiring new equipment investment. This reduces the initial equipment investment cost when manufacturing semiconductor devices.

[0448] In the supply processing of impurity element 189, it is preferable to control the processing conditions so that the concentration of the impurity element in the portion of the semiconductor layer 108 that overlaps with the conductive layer 112a or conductive layer 112b is higher than the concentration of the impurity element in other regions. This allows for the supply of the most suitable concentration of impurity element 189 to the source and drain regions of the semiconductor layer 108.

[0449] As the source gas for impurity element 189, a gas containing the aforementioned impurity element can be used. When supplying boron, B₂H₆ gas or BF₃ gas is typically used. Furthermore, when supplying phosphorus, PH₃ gas is typically used. Alternatively, a mixture of these source gases diluted with hydrogen or a rare gas can also be used.

[0450] In addition to the above, source gases can include CH4, N2, NH3, AlH3, AlCl3, SiH4, Si2H6, F2, HF, H2, (C5H5)2Mg, and rare gases. Furthermore, the ion source is not limited to gases; solids or liquids can also be heated to vaporize them.

[0451] For example, it is preferable to use a gas supply containing boron and hydrogen as impurity element 189. In this case, impurity element 189 can be added without mass separation, and the low resistance of semiconductor layer 108 can be easily achieved, thus improving the productivity and characteristics of the semiconductor device, which is therefore preferred.

[0452] By setting conditions such as accelerating voltage and dosage according to the composition, density, and thickness of insulating layer 106 and semiconductor layer 108, the supply of impurity element 189 can be controlled.

[0453] Note that there is no limitation on the method of supplying the impurity element 189, and for example, plasma treatment or treatment using thermal diffusion due to heating can be performed. In the case of using a plasma treatment method, the impurity element can be supplied by first generating plasma in a gas atmosphere containing a supplied halogen and then performing plasma treatment. As a device for generating the above-described plasma, a dry etching device, an ashing device, a plasma CVD device, a high-density plasma CVD device, or the like can be used.

[0454] In one embodiment of the present application, the impurity element 189 is supplied to the semiconductor layer 108 through the insulating layer 106. Thus, a decrease in crystallinity of the semiconductor layer 108 at the time of supply of the impurity element 189 can be suppressed. Accordingly, an increase in resistance due to a decrease in crystallinity can be suppressed.

[0455] In addition, when the insulating layer 106 is deposited after the addition of the impurity element 189, the deposition chamber of the insulating layer 106 can be contaminated. Thus, it is preferable to add the impurity element 189 after the deposition of the insulating layer 106.

[0456] On the other hand, the insulating layer 106 can be deposited on the semiconductor layer 108 after the direct addition of the impurity element 189 to the semiconductor layer 108. Thus, damage to the insulating layer 106 due to the addition of the impurity element 189 can be suppressed.

[0457] In addition, it is preferable to perform the supply process of the impurity element 189 while heating the substrate 102. Thus, damage to the semiconductor layer 108 at the time of addition of the impurity element 189 can be repaired. In other words, the impurity element 189 can be added to the semiconductor layer 108 in parallel with the repair of damage accompanying the addition. In addition, damage to the insulating layer 106 at the time of addition of the impurity element 189 can also be repaired.

[0458] The temperature of the substrate in the supply process of the impurity element 189 is preferably higher than or equal to 150 °C and lower than the strain point of the substrate, more preferably higher than or equal to 200 °C and lower than 500 °C, still more preferably higher than or equal to 200 °C and lower than 450 °C, yet more preferably higher than or equal to 250 °C and lower than 400 °C, further more preferably higher than or equal to 250 °C and lower than 350 °C, or preferably higher than or equal to 300 °C and lower than 400 °C, more preferably higher than or equal to 300 °C and lower than 350 °C.

[0459] Further, heating treatment can be performed after the supply of the impurity element 189. By performing the heating treatment, damage to the semiconductor layer 108 and the insulating layer 106 in the supply process of the impurity element 189 can be repaired.

[0460] In addition, as described later in Embodiment Mode 1, when heat treatment is performed after the deposition of the insulating layer 106 without adding the impurity element 189, the sheet resistance of the semiconductor layer 108 and the contact resistance between the semiconductor layer 108 and the conductive layer 112a or the conductive layer 112b are sometimes increased. On the other hand, when heat treatment is performed after the addition of the impurity element 189, the sheet resistance and the contact resistance are less likely to be increased as compared with the case where the impurity element 189 is not added, and thus low resistance can be maintained. Note that when the temperature of heat treatment is too high, the sheet resistance and the contact resistance are sometimes increased even when the impurity element 189 is added.

[0461] Therefore, the temperature of heat treatment after the addition of the impurity element 189 is preferably higher than or equal to 150 °C and lower than the strain point of the substrate, more preferably higher than or equal to 200 °C and lower than 500 °C, still more preferably higher than or equal to 200 °C and lower than 450 °C, yet more preferably higher than or equal to 250 °C and lower than 400 °C, further more preferably higher than or equal to 250 °C and lower than 350 °C, or higher than or equal to 300 °C and lower than 400 °C, and even more preferably higher than or equal to 300 °C and lower than 350 °C.

[0462] By using an element which is stabilized by bonding to oxygen as the impurity element 189, the impurity element 189 can be prevented from being removed due to heat treatment or the like in a manufacturing process of a semiconductor device. Thus, even when heat treatment is performed after the addition of the impurity element 189 or a deposition process is performed while heating the substrate, low resistance can be maintained in the low-resistance region 108n.

[0463] Note that the above description can be applied to heat treatment.

[0464] Next, a conductive layer 104 is formed over the insulating layer 106 (see FIG. 1B). Figure 14B The conductive film which becomes the conductive layer 104 is formed by, for example, a sputtering method, a thermal CVD method (including an MOCVD method), or an ALD method. The conductive film is processed after a resist mask is formed thereover by a photolithography process, whereby the island-shaped conductive layer 104 which serves as a gate electrode is formed.

[0465] The semiconductor device of one embodiment of the present application can be manufactured by the above process.

[0466] Embodiment Mode 1 can be combined with other embodiment modes as appropriate.

[0467] (Embodiment 3)

[0468] In this embodiment mode, a semiconductor device of one embodiment of the present application is described with reference to FIGS. 15 to 19.

[0469] FIG. 15 illustrates a circuit diagram of a semiconductor device of one embodiment of the present application. FIGS. 16 to 18 illustrate top views and cross-sectional views of a semiconductor device of one embodiment of the present application. Hereinafter, as a transistor included in a semiconductor device of one embodiment of the present application, a transistor 100A is mainly described. A semiconductor device of one embodiment of the present application is not limited thereto and can include any one or a plurality of the above-described transistors 100, the transistors 100B to 1001.

[0470] A semiconductor device of one embodiment of the present application includes at least two transistors, and any one of the gate, the source, and the drain of one transistor is electrically connected to any one of the gate, the source, and the drain of the other transistor.

[0471] For example, Figure 15A The semiconductor device illustrated in FIG. 15 includes the transistor 100A and the transistor 200A. One of the source and the drain of the transistor 200A is electrically connected to the gate of the transistor 100A.

[0472] Note that in Figures 15A to 15C , each transistor is an n-channel transistor, but one embodiment of the present application is not limited to this. One or both of the transistor 100A and the transistor 200A can be a p-channel transistor.

[0473] [Semiconductor device 10A]

[0474] Figure 15B A circuit diagram of the semiconductor device 10A is illustrated. Figure 16A A top view of the semiconductor device 10A is illustrated. Figure 16B is a cross-sectional view along the dotted line A1-A2 in Figure 16A .

[0475] The semiconductor device 10A includes the transistor 100A and the transistor 200A. The other of the source and the drain of the transistor 200A is electrically connected to the other of the source and the drain of the transistor 100A.

[0476] As illustrated in Figure 16B , the transistor 100A and the transistor 200A are each provided over a substrate 102.

[0477] Since the transistor 100A has the above structure, detailed description is omitted (see Figure 5A and Figure 5B ).

[0478] As illustrated in Figure 16A and Figure 16BAs shown in FIG. 1A, the transistor 200A includes the conductive layer 112c, the insulating layer 110 (the insulating layers 110a, 110b, 110c, 110d, 110e), the semiconductor layer 108a (including the low-resistance region 108an), the conductive layer 112b, the insulating layer 106, and the conductive layer 104a. The insulating layer 110 is provided with an opening portion 141a reaching the conductive layer 112c, and the conductive layer 112b is provided with an opening portion 143a overlapping with the opening portion 141a.

[0479] The conductive layer 112c is used as one of a source electrode and a drain electrode of the transistor 200A. The conductive layer 112c can be formed using the same material and the same process as the conductive layer 112a.

[0480] The semiconductor layer 108a can be formed using the same material as the semiconductor layer 108 in the same process. Alternatively, the semiconductor layer 108 and the semiconductor layer 108a can be formed using different materials in different processes.

[0481] The conductive layer 112b is used as the other of the source electrode and the drain electrode of the transistor 100A and is used as the other of the source electrode and the drain electrode of the transistor 200A. By the transistor 100A and the transistor 200A sharing the conductive layer 112b, the occupied area of the semiconductor device can be reduced.

[0482] The conductive layer 104a is used as a gate electrode of the transistor 200A. The conductive layer 104a can be formed using the same material and the same process as the conductive layer 104.

[0483] The shapes and sizes (diameter, etc.) of the opening portion 141 and the opening portion 141a provided in the insulating layer 110 can be the same or different. Similarly, the shapes and sizes (diameter, etc.) of the opening portion 143 and the opening portion 143a provided in the conductive layer 112b can be the same or different.

[0484] The insulating layer 195 is used as a protective layer. The insulating layer 195 is preferably formed using a material from which impurities are less likely to diffuse. By providing the insulating layer 195, diffusion of impurities from the outside into the transistor can be effectively suppressed, so that the reliability of the semiconductor device can be improved. As the impurities, for example, water and hydrogen can be given. For example, the insulating layer 195 includes one or both of an inorganic insulating layer and an organic insulating layer. The insulating layer 195 can have a stacked structure of an inorganic insulating layer and an organic insulating layer.

[0485] As the inorganic insulating film that can be used for the insulating layer 195, for example, an oxide insulating film, a nitride insulating film, an oxynitride insulating film, and an oxynitride insulating film can be given. Specific examples of these inorganic insulating films have been given in the description of the insulating layer 110. More specifically, one or more of silicon nitride, silicon oxynitride, silicon oxynitride, aluminum oxide, aluminum oxynitride, aluminum nitride, hafnium oxide, and hafnium aluminum oxide can be used for the insulating layer 195. One or more of an acrylic resin and a polyimide resin, for example, can be used for the insulating layer 195 as an organic material.

[0486] [Semiconductor device 10B]

[0487] Figure 15C A circuit diagram of the semiconductor device 10B is shown. Figure 17A A top view of the semiconductor device 10B is shown. Figure 17B is a cross-sectional view along the dotted line A1-A2 in Figure 17A

[0488] The semiconductor device 10B includes a transistor 100A and a transistor 200A. One of a source and a drain of the transistor 200A is electrically connected to one of a source and a drain of the transistor 100A.

[0489] The transistor 100A and the transistor 200A are each provided over a substrate 102.

[0490] The transistor 100A has the above structure, and thus detailed description is omitted.

[0491] The transistor 200A includes a conductive layer 112c, an insulating layer 110 (insulating layers 110a, 110b, 110c, 110d, and 110e), a semiconductor layer 108a, a conductive layer 112a, an insulating layer 106, and a conductive layer 104a.

[0492] The conductive layer 112c is used as one of a source electrode and a drain electrode of the transistor 200A. The conductive layer 112c can be formed using the same material and the same process as the conductive layer 112b.

[0493] The conductive layer 112a is used as the other of the source electrode and the drain electrode of the transistor 100A and is used as the other of the source electrode and the drain electrode of the transistor 200A. By the transistor 100A and the transistor 200A sharing the conductive layer 112a, the area occupied by the semiconductor device can be reduced.

[0494] The conductive layer 104a is used as a gate electrode of the transistor 200A. The conductive layer 104a can be formed using the same material and the same process as the conductive layer 104.

[0495] [Semiconductor device 10C]

[0496] ​ Figure 15D A circuit diagram of the semiconductor device 10C is shown. Figure 18A A plan view of the semiconductor device 10C is shown. Figure 18B is a cross-sectional view along the dotted line A1-A2 in Figure 18A

[0497] The semiconductor device 10C includes the transistor 100A and the transistor 250. One of the source and the drain of the transistor 250 is electrically connected to one of the source and the drain of the transistor 100A.

[0498] Note that in Figures 15D to 15H , the transistor 100A is an n-channel transistor and the transistor 250 is a p-channel transistor, but one embodiment of the present application is not limited to this. Both the transistor 100A and the transistor 250 can be n-channel or p-channel. Further, the transistor 100A can be a p-channel transistor and the transistor 250 can be an n-channel transistor.

[0499] The transistor 100A and the transistor 250 are each provided over the substrate 102.

[0500] The semiconductor device 10C includes the conductive layer 259 over the substrate 102, includes the insulating layer 252 over the substrate and the conductive layer 259, and includes the semiconductor layer 253 over the insulating layer 252. Further, the insulating layer 254 is included over the insulating layer 252 and the semiconductor layer 253, and the conductive layer 255 is included over the insulating layer 254. The semiconductor layer 253 and the conductive layer 255 include regions overlapping with each other.

[0501] Further, the insulating layer 256 is included over the insulating layer 254 and the conductive layer 255. Further, in a region overlapping with part of the semiconductor layer 253, an opening portion 257a is provided in the insulating layer 254 and the insulating layer 256. Further, in a region overlapping with another part of the semiconductor layer 253, an opening portion 257b is provided in the insulating layer 254 and the insulating layer 256.

[0502] Further, the conductive layer 258a is provided over the insulating layer 256 and in the inside of the opening portion 257a, and the conductive layer 258b is provided over the insulating layer 256 and in the inside of the opening portion 257b. The conductive layer 258a is electrically connected to the semiconductor layer 253 in the opening portion 257a. Further, the conductive layer 258b is electrically connected to the semiconductor layer 253 in the opening portion 257b.

[0503] The semiconductor layer 253 has a drain region 253a, a channel formation region 253b, and a source region 253c. In the semiconductor layer 253, a region overlapping with the conductive layer 255 is used as the channel formation region 253b. The drain region 253a is electrically connected to the conductive layer 258a, and the source region 253c is electrically connected to the conductive layer 258b.​

[0504] Further, the insulating layer 256, the conductive layer 258a, and the conductive layer 258b are provided with the insulating layer 110 (insulating layers 110a, 110b, 110c, 110d, 110e), and the conductive layer 112b is provided over the insulating layer 110.

[0505] Further, in a region overlapping with a part of the conductive layer 258a, the conductive layer 112b and the insulating layer 110 are provided with an opening portion 146 Figure 18A Further, the inside of the opening portion 146 includes the semiconductor layer 108.

[0506] Further, the insulating layer 106 is included over the insulating layer 110, the conductive layer 112b, and the semiconductor layer 108, and the conductive layer 104 is included over the insulating layer 106. Further, the insulating layer 195 is included over the insulating layer 106 and the conductive layer 104.

[0507] The conductive layer 259 is used as a back gate electrode of the transistor 250. Therefore, the conductive layer 259 preferably overlaps with the channel formation region 253b and extends beyond the end portion of the channel formation region 253b. In other words, the conductive layer 259 is preferably larger than the channel formation region 253b. Further, the conductive layer 259 preferably extends beyond the end portion of the semiconductor layer 253. In other words, the conductive layer 259 is preferably larger than the semiconductor layer 253.

[0508] The back gate electrode is arranged in a manner that the semiconductor layer is interposed between the gate electrode and the channel formation region. Further, by changing the potential of the back gate electrode, the threshold voltage of the transistor can be changed. The potential of the back gate electrode can be a ground potential or an arbitrary potential.

[0509] The back gate electrode is formed using a conductive layer and can function in the same manner as the gate electrode. For example, the potential of the back gate electrode can be made the same as that of the gate electrode.

[0510] The back gate electrode can be formed using the same material and method as the gate electrode, the source electrode, the drain electrode, and the like. Further, since the gate electrode and the back gate electrode are conductive layers, they have a function of preventing an electric field generated outside the transistor from affecting the semiconductor layer in which the channel is formed (particularly, an electric field shielding function against static electricity). That is, variation in electrical characteristics of the transistor due to an external electric field such as static electricity can be prevented. Further, by providing the back gate electrode, the amount of change in the threshold voltage of the transistor before and after a BT (Bias Temperature) stress test can be reduced. By providing the back gate electrode, characteristics of the transistor are less likely to be non-uniform, and the reliability of the semiconductor device can be improved.

[0511] The semiconductor layer 253 is used as a semiconductor layer that forms a channel of the transistor 250, the insulating layer 254 is used as a gate insulating layer, and the conductive layer 255 is used as a gate electrode. In addition, the conductive layer 258a is used as a drain electrode of the transistor 250, and the conductive layer 258b is used as a source electrode.

[0512] As the transistor 250, an OS transistor can also be used, like the transistor 100A.

[0513] Here, the semiconductor layer 108 and the semiconductor layer 253 can be formed using the same material or different materials.

[0514] In addition, as the transistor 250, a transistor in which silicon is used for a channel formation region (Si transistor) can also be used.

[0515] As silicon, single crystal silicon, polycrystal silicon, amorphous silicon, or the like can be given. In particular, a transistor including LTPS in a semiconductor layer (hereinafter also referred to as an LTPS transistor) can be used. An LTPS transistor has high field-effect mobility and good frequency characteristics.

[0516] The transistor 100A has the same structure as described above except that the conductive layer 258a is used instead of the conductive layer 112a.

[0517] The conductive layer 258a is used as one of a source electrode and a drain electrode of the transistor 100A and one of a source electrode and a drain electrode of the transistor 250. By sharing the conductive layer 258a between the transistor 100A and the transistor 250, the area occupied by the semiconductor device can be reduced.

[0518] As described above, the transistor 100A is a vertical channel transistor. On the other hand, in the transistor 250, current flowing through the semiconductor layer flows in a lateral direction, i.e., a direction parallel or substantially parallel to a surface of the substrate 102. Such a transistor can be referred to as a lateral channel transistor or a horizontal channel transistor.

[0519] Thus, the semiconductor device of one embodiment of the present application can include a lateral channel transistor in addition to a vertical channel transistor.

[0520] As illustrated in FIG. 25A, in the transistor 250, a back gate and a gate can be electrically connected. In addition, as illustrated in FIG. 25B, in the transistor 250, a back gate can be electrically connected to a source or a drain. Furthermore, as illustrated in FIG. 25C, the transistor 250 can not include a back gate. Figure 15E Figure 15F Figure 15G

[0521] [Semiconductor Device 10D]

[0522] Figure 15H A circuit diagram of the semiconductor device 10D is illustrated.​​​ Figure 19A A plan view of the semiconductor device 10D is shown. Figure 19B is a cross-sectional view along the dot-dash line A1-A2 in Figure 19A

[0523] The semiconductor device 10D includes the transistor 100A and the transistor 250. The gate of the transistor 250 is electrically connected to one of the source and the drain of the transistor 100A.

[0524] The semiconductor device 10D differs from the semiconductor device 10C in that the opening portion 146 overlaps with the conductive layer 255 which is used as a gate electrode of the transistor 250. Thus, in the semiconductor device 10C, the transistor 100A is provided to overlap with the gate electrode of the transistor 250. In the semiconductor device 10D, a part of each of the conductive layer 112b and the insulating layer 110 is selectively removed in a region overlapping with the conductive layer 255 to form the opening portion 146.

[0525] In the semiconductor device 10D, the opening portion 257a is formed in a region overlapping with the drain region 253a of the semiconductor layer 253 by selectively removing a part of each of the insulating layer 254 and the insulating layer 110. In addition, in the semiconductor device 10D, the opening portion 257b is formed in a region overlapping with the source region 253c of the semiconductor layer 253 by selectively removing a part of each of the insulating layer 254 and the insulating layer 110. Figure 19A Figure 19B In the semiconductor device 10D, the opening portion 257a is formed in a region overlapping with the drain region 253a of the semiconductor layer 253 by selectively removing a part of each of the insulating layer 254 and the insulating layer 110. In addition, in the semiconductor device 10D, the opening portion 257b is formed in a region overlapping with the source region 253c of the semiconductor layer 253 by selectively removing a part of each of the insulating layer 254 and the insulating layer 110.

[0526] By providing the transistor 100A and the transistor 250 to overlap with each other, a semiconductor device with a further reduced area occupation can be realized.

[0527] The semiconductor device 10D differs from the semiconductor device 10C in the structures of the opening portion 257a, the opening portion 257b, the conductive layer 258a, and the conductive layer 258b.

[0528] In the semiconductor device 10D, the opening portion 257a is formed in a region overlapping with the drain region 253a of the semiconductor layer 253 by selectively removing a part of each of the insulating layer 254 and the insulating layer 110. In addition, in the semiconductor device 10D, the opening portion 257b is formed in a region overlapping with the source region 253c of the semiconductor layer 253 by selectively removing a part of each of the insulating layer 254 and the insulating layer 110.

[0529] In addition, in the semiconductor device 10D, the conductive layer 258a and the conductive layer 258b are provided over the insulating layer 110.

[0530] ​​In the semiconductor device 10D, conductive layers 258a, 258b and conductive layer 112b can be formed simultaneously using the same materials and the same manufacturing process. Because it is not necessary to manufacture conductive layers 258a, 258b and conductive layer 112b separately, the manufacturing process of the semiconductor device can be shortened, thereby improving the productivity of the semiconductor device.

[0531] In addition, one aspect of the semiconductor device of the present invention includes at least one transistor and at least one capacitor, wherein the source or drain of the transistor is electrically connected to one of a pair of electrodes of the capacitor. Figure 15I An example is shown where the source or drain of transistor 100 is electrically connected to one electrode of capacitor 190.

[0532] This implementation method can be appropriately combined with other implementation methods.

[0533] (Implementation Method 4)

[0534] In this embodiment, refer to Figures 20 to 25 This invention describes a display device according to one aspect of the present invention.

[0535] The display device in this embodiment can be a high-resolution display device or a large-screen display device. Therefore, the display device in this embodiment can be used as a display unit for devices such as: electronic devices with large screens, such as televisions, desktop or laptop personal computers, monitors for computers, digital signage, large game machines such as pinball machines, etc.; digital cameras; digital video cameras; digital photo frames; mobile phones; portable game consoles; portable information terminals; and sound reproduction devices.

[0536] Furthermore, the display device in this embodiment can be a high-definition display device. Therefore, for example, the display device in this embodiment can be used as the display unit of information terminal devices (wearable devices) such as watch-type and bracelet-type devices, as well as the display unit of wearable devices that can be worn on the head, such as VR devices such as head-mounted displays (HMDs) and AR devices such as glasses-type devices.

[0537] One aspect of the semiconductor device of the present invention can be used in a display device or a module including the display device. Examples of modules including the display device include modules in which the display device is mounted with connectors such as flexible printed circuit boards (FPC) or TCP (Tape Carrier Package), and modules in which integrated circuits (ICs) are mounted via COG (Chip On Glass) or COF (Chip On Film) methods.

[0538] The display device of this embodiment can also have the function of a touch panel. For example, various detection elements (also called sensor elements) capable of detecting the proximity or contact of a detection object such as a finger can be used in the display device.

[0539] For example, sensor types include electrostatic capacitive, resistive film, surface acoustic wave, infrared, optical, and pressure-sensitive types.

[0540] As electrostatic capacitive types, there are surface-type electrostatic capacitive types and projection-type electrostatic capacitive types. Furthermore, as projection-type electrostatic capacitive types, there are self-capacitance types and mutual-capacitance types. Mutual-capacitance types are preferred, as they allow for simultaneous multi-point detection.

[0541] Examples of touch panels include Out-Cell, On-Cell, and In-Cell types. Note that an In-Cell touch panel refers to a structure in which electrodes constituting the detection element are provided on one or both of the substrate supporting the display element and the opposing substrate.

[0542] [Display device 50A]

[0543] Figure 20 This is a 3D view of display device 50A.

[0544] The display device 50A has a structure that bonds substrate 152 and substrate 151. Figure 20 In the image, substrate 152 is represented by a dashed line.

[0545] The display device 50A includes a display section 162, a connection section 140, a circuit section 164, a conductive layer 165, etc. Figure 20 An example is shown where display device 50A is equipped with IC173 and FPC172. Therefore, it is also possible to... Figure 20 The structure shown is called a display module including display device 50A, IC and FPC.

[0546] The connecting portion 140 is disposed on the outer side of the display portion 162. The connecting portion 140 may be disposed along one or more edges of the display portion 162. There may also be one or more connecting portions 140. Figure 20 An example is shown where the connection portion 140 is arranged around the four sides of the display portion. In the connection portion 140, the common electrode of the display element is electrically connected to the conductive layer, and a potential can be supplied to the common electrode.

[0547] The circuit section 164 may include, for example, a scan line driving circuit (also known as a gate driver). Alternatively, the circuit section 164 may include both a scan line driving circuit and a signal line driving circuit (also known as a source driver).

[0548] The conductive layer 165 has a function of supplying a signal and a power to the display portion 162 and the circuit portion 164. The signal and the power are supplied from an external source to the conductive layer 165 through an FPC 172 or supplied from an IC 173 to the conductive layer 165.

[0549] Figure 20 An example in which the IC 173 is provided over the substrate 151 by a COG method or a COF method is shown. As the IC 173, an IC including one or both of a scan line driver circuit and a signal line driver circuit can be used, for example. Note that the display device 50A and the display module do not necessarily have to be provided with the IC. The IC can be mounted on the FPC by a COF method or the like.

[0550] The semiconductor device of one embodiment of the present application can be used in one or both of the display portion 162 and the circuit portion 164 of the display device 50A, for example.

[0551] For example, when the semiconductor device of one embodiment of the present application is used for a pixel circuit of a display device, the area occupied by the pixel circuit can be reduced, and a high-definition display device can be achieved. Furthermore, for example, when the semiconductor device of one embodiment of the present application is used for a driver circuit (e.g., one or both of a gate line driver circuit and a source line driver circuit) of a display device, the area occupied by the driver circuit can be reduced, and thus a display device with narrow bezels can be achieved. In addition, the semiconductor device of one embodiment of the present application has good electrical characteristics, and by using the semiconductor device for a display device, the reliability of the display device can be improved.

[0552] The display portion 162 is an image display region in the display device 50A and includes a plurality of pixels 201 arranged periodically. Figure 20 An enlarged view of one pixel 201 is shown.

[0553] There is no particular limitation on the arrangement of the pixels in the display device of this embodiment, and various methods can be employed. As the arrangement of the pixels, for example, a stripe arrangement, an S stripe arrangement, a matrix arrangement, a Delta arrangement, a Bayer arrangement, and a Pentile arrangement can be given.

[0554] Figure 20 The pixel 201 shown includes a sub-pixel 11R which emits red light, a sub-pixel 11G which emits green light, and a sub-pixel 11B which emits blue light. There is no particular limitation on the number of sub-pixels included in one pixel.

[0555] Each of the sub-pixels 11R, 11G, and 11B includes a display element and a circuit which controls driving of the display element.

[0556] As the display element, a liquid crystal element and a light-emitting element can be given. In addition to the light-emitting element and the liquid crystal element, other display elements can be used, such as a shutter type or a light interference type MEMS (Micro Electro Mechanical Systems) element, a display element using a microcapsule, an electrophoretic display element, an electronic ink element, a display element using an electronic paper, a display element using a twisting ball, a display element using a piezoelectric actuator, and a display element using a thermoelectric convertor.

[0557] As the display device using a liquid crystal element, a transmissive liquid crystal display device, a reflective liquid crystal display device, and a semi-transmissive liquid crystal display device can be given.

[0558] As the mode of the display device using a liquid crystal element, a vertical alignment (VA) mode, a fringe field switching (FFS) mode, an in-plane switching (IPS) mode, a twisted nematic (TN) mode, an axially symmetric aligned micro-cell (ASM) mode, an optically compensated birefringence (OCB) mode, a ferroelectric liquid crystal (FLC) mode, an anti-ferroelectric liquid crystal (AFLC) mode, an electrically controlled birefringence (ECB) mode, and a guest-host mode can be given. As the VA mode, a multi-domain vertical alignment (MVA) mode, a patterned vertical alignment (PVA) mode, and an advanced super view (ASV) mode can be given.

[0559] As a liquid crystal material that can be used for a liquid crystal element, for example, a thermotropic liquid crystal, a low-molecular liquid crystal, a high-molecular liquid crystal, a polymer dispersed liquid crystal (PDLC), a polymer network liquid crystal (PNLC), a ferroelectric liquid crystal, and an anti-ferroelectric liquid crystal can be given. These liquid crystal materials exhibit a cholesteric phase, a smectic phase, a cubic phase, a chiral nematic phase, an isotropic phase, a blue phase, or the like depending on conditions. In addition, as a liquid crystal material, either one of a positive liquid crystal and a negative liquid crystal can be used, and can be selected depending on a mode or design used.

[0560] As a light emitting element, for example, a self-light emitting light emitting element such as an LED (Light Emitting Diode), an OLED (Organic LED), a semiconductor laser, or the like can be given. As an LED, for example, a small LED, a micro LED, or the like can be used.

[0561] As a light emitting substance contained in a light emitting element, for example, a substance that emits fluorescent light (a fluorescent material), a substance that emits phosphorescent light (a phosphorescent material), a substance that exhibits thermally activated delayed fluorescence (a TADF (Thermally Activated Delayed Fluorescence) material), and an inorganic compound (a quantum dot material or the like) can be given.

[0562] A light emitting color of a light emitting element can be infrared, red, green, blue, cyan, magenta, yellow, white, or the like. Furthermore, when a light emitting element has a microcavity structure, color purity can be further improved.

[0563] In a pair of electrodes included in a light emitting element, one electrode is used as an anode and the other electrode is used as a cathode.

[0564] A display device of one embodiment of the present application can have any of a top emission type which emits light in a direction opposite to a substrate on which a light emitting element is formed, a bottom emission type which emits light toward a substrate on which a light emitting element is formed, and a dual emission type which emits light on both sides.

[0565] Figure 21A One example of a cross section of a portion of a region including the FPC 172, a portion of the circuit portion 164, a portion of the display portion 162, a portion of the connection portion 140, and a portion of a region including an end portion of the display device 50A is shown.

[0566] Figure 21AThe display device 50A illustrated includes transistors 205D, 205R, 205G, 205B, light emitting elements 130R, 130G, 130B, and the like between the substrate 151 and the substrate 152. The light emitting element 130R is a display element included in a sub-pixel 11R that emits red light, the light emitting element 130G is a display element included in a sub-pixel 11G that emits green light, and the light emitting element 130B is a display element included in a sub-pixel 11B that emits blue light.

[0567] The display device 50A employs an SBS structure. The SBS structure can improve the degree of freedom in selection of materials and structures because the materials and structures of the light emitting elements can be optimized, and can easily achieve an improvement in luminance and reliability.

[0568] In addition, the display device 50A employs a top emission type. In the top emission type, the transistors and the like can be arranged so as to overlap with the light emitting regions of the light emitting elements, and thus the aperture ratio of the pixels can be further improved as compared with the bottom emission type.

[0569] The transistors 205D, 205R, 205G, 205B are each formed over the substrate 151. These transistors can be manufactured using the same material and the same process.

[0570] In this embodiment mode, an example in which an OS transistor is used as the transistors 205D, 205R, 205G, 205B is described. As the transistors 205D, 205R, 205G, 205B, a transistor of one embodiment of the present application can be used. That is, in the display device 50A, both the display portion 162 and the circuit portion 164 include a transistor of one embodiment of the present application. By using a transistor of one embodiment of the present application in the display portion 162, the pixel size can be reduced and high definition can be achieved. In addition, by using a transistor of one embodiment of the present application in the circuit portion 164, the area occupied by the circuit portion 164 can be reduced and narrow bezel design can be achieved. In this embodiment mode, an example in which the transistor 100A Figure 5A and Figure 5B ) is used as a transistor of one embodiment of the present application is described, but the present application is not limited thereto. The transistor of one embodiment of the present application can be formed in accordance with the description of the above embodiment modes.

[0571] Specifically, the transistors 205D, 205R, 205G, and 205B each include the conductive layer 104 serving as a gate electrode, the insulating layer 106 serving as a gate insulating layer, the conductive layer 112a and the conductive layer 112b serving as a source or a drain, the semiconductor layer 108 containing a metal oxide, and the insulating layers 110 (insulating layers 110a, 110b, 110c, 110d, and 110e). Here, the same hatching is applied to a plurality of layers obtained by processing the same conductive film. The insulating layer 110 is positioned between the conductive layer 112a and the semiconductor layer 108. The insulating layer 106 is positioned between the conductive layer 104 and the semiconductor layer 108.

[0572] Note that the transistor included in the display device of this embodiment is not limited to the transistor of one embodiment of the present application. For example, a transistor including the transistor of one embodiment of the present application and a transistor of another structure can be combined.

[0573] The display device of this embodiment can include any one or more of a planar transistor, a staggered transistor, and an inverted staggered transistor, for example. The transistor included in the display device of this embodiment has any one of a top-gate structure and a bottom-gate structure. Alternatively, a gate electrode can be provided above and below a semiconductor layer forming a channel.

[0574] Alternatively, the display device of this embodiment can include an Si transistor.

[0575] In increasing the emission luminance of the light-emitting element included in the pixel circuit, it is necessary to increase the amount of current flowing through the light-emitting element. For this reason, it is necessary to increase the source-drain voltage of the driver transistor included in the pixel circuit. Since the source-drain voltage of the OS transistor is higher than that of the Si transistor, a high voltage can be applied to the source-drain of the OS transistor. Thus, by using the OS transistor as the driver transistor included in the pixel circuit, the amount of current flowing through the light-emitting element can be increased, and the emission luminance of the light-emitting element can be increased.

[0576] In addition, when the transistor operates in the saturation region, the OS transistor can make the change in the source-drain current with respect to the change in the gate-source voltage smaller than the Si transistor. Thus, by using the OS transistor as the driver transistor included in the pixel circuit, the current flowing through the source-drain can be determined in detail depending on the change in the gate-source voltage, and thus the amount of current flowing through the light-emitting element can be controlled. Thus, the number of gray scales of the pixel circuit can be increased.

[0577] Further, in comparison with a Si transistor, the OS transistor can flow a stable current (saturation current) even if the voltage between the source and the drain is gradually increased, with respect to the saturation characteristics of the current flowing through the transistor when operating in the saturation region. Thus, by using the OS transistor as a driver transistor, a stable current can flow through the light emitting element even if, for example, the current-voltage characteristics of the light emitting element are uneven. That is, the source-drain current of the OS transistor hardly changes even if the voltage between the source and the drain is changed when operating in the saturation region, and thus the luminance of the light emitting element can be stabilized.

[0578] The transistors included in the circuit portion 164 and the transistors included in the display portion 162 can have the same structure or different structures. The plurality of transistors included in the circuit portion 164 can have the same structure or two or more different structures. Similarly, the plurality of transistors included in the display portion 162 can have the same structure or two or more different structures.

[0579] All the transistors included in the display portion 162 can be OS transistors, all the transistors included in the display portion 162 can be Si transistors, part of the transistors included in the display portion 162 can be OS transistors and the remaining transistors can be Si transistors.

[0580] For example, by using both LTPS transistors and OS transistors in the display portion 162, a display device having low power consumption and high driving capability can be realized. Further, the structure combining LTPS transistors and OS transistors is sometimes referred to as LTPO. As a more preferable example, a structure in which an OS transistor is used for a transistor serving as a switch that controls the conduction / non-conduction between wirings, and an LTPS transistor is used for a transistor that controls current, and the like can be given.

[0581] For example, one of the transistors included in the display portion 162 is used as a transistor that controls the current flowing through the light emitting element and can be referred to as a driver transistor. One of the source and the drain of the driver transistor is electrically connected to the pixel electrode of the light emitting element. As the driver transistor, an LTPS transistor is preferably used. Thus, the current flowing through the light emitting element in the pixel circuit can be increased.

[0582] On the other hand, one of the transistors included in the display portion 162 is used as a switch that controls the selection and non-selection of a pixel and can be referred to as a selection transistor. The gate of the selection transistor is electrically connected to the gate line, and one of the source and the drain is electrically connected to the source line (signal line). The selection transistor preferably uses an OS transistor. Thus, even if the frame rate is significantly small (for example, 1 fps or less), the gradation of the pixel can be maintained, and thus by stopping the driver when displaying a still image, the power consumption can be reduced.

[0583] An insulating layer 218 is provided so as to cover the transistors 205D, 205R, 205G, 205B, and an insulating layer 235 is provided on the insulating layer 218.

[0584] The insulating layer 218 is preferably used as a protective layer of the transistors. The insulating layer 218 is preferably formed using a material which is not likely to diffuse impurities such as water and hydrogen. Thus, the insulating layer 218 can be used as a barrier layer. By employing such a structure, diffusion of impurities from the outside into the transistors can be effectively suppressed, and thus the reliability of the display device can be improved.

[0585] The insulating layer 218 preferably includes one or more inorganic insulating films. As the inorganic insulating film, for example, an oxide insulating film, a nitride insulating film, an oxynitride insulating film, and a nitride oxide insulating film can be given. Specific examples of these inorganic insulating films are as described above.

[0586] The insulating layer 235 is preferably used as a planarization layer, and an organic insulating film is suitably used. As a material which can be used for the organic insulating film, for example, an acrylic resin, a polyimide resin, an epoxy resin, a polyamide resin, a polyimide amide resin, a siloxane resin, a benzocyclobutene-based resin, a phenol resin, a precursor of these resins, and the like can be given. Further, the insulating layer 235 can employ a stacked structure of an organic insulating film and an inorganic insulating film. The topmost surface layer of the insulating layer 235 is preferably used as an etching protective layer. Thus, when the pixel electrodes 111R, 111G, 111B, and the like are processed, formation of a recess in the insulating layer 235 can be suppressed. Alternatively, a recess can be provided in the insulating layer 235 when the pixel electrodes 111R, 111G, 111B, and the like are processed.

[0587] The insulating layer 235 is provided with the light emitting elements 130R, 130G, 130B.

[0588] The light emitting element 130R includes the pixel electrode 111R on the insulating layer 235, the EL layer 113R on the pixel electrode 111R, and the common electrode 115 on the EL layer 113R. Figure 21A The illustrated light emitting element 130R emits red light (R). The EL layer 113R includes a light emitting layer which emits red light.

[0589] The light emitting element 130G includes the pixel electrode 111G on the insulating layer 235, the EL layer 113G on the pixel electrode 111G, and the common electrode 115 on the EL layer 113G. Figure 21A The illustrated light emitting element 130G emits green light (G). The EL layer 113G includes a light emitting layer which emits green light.

[0590] The light-emitting element 130B includes a pixel electrode 111B on an insulating layer 235, an EL layer 113B on the pixel electrode 111B, and a common electrode 115 on the EL layer 113B. Figure 21A The light-emitting element 130B shown emits blue light (B). The EL layer 113B includes a light-emitting layer that emits blue light.

[0591] Note that in Figure 21A The EL layers 113R, 113G, and 113B are shown with the same thickness, but this is not a limitation. The thicknesses of the EL layers 113R, 113G, and 113B can also be different. For example, it is preferable to set the thickness to enhance the optical path of the light emitted by the EL layers 113R, 113G, and 113B. This allows for the realization of a microcavity structure to improve the color purity of the light emitted from each light-emitting element.

[0592] Pixel electrode 111R is electrically connected to the conductive layer 112b of transistor 205R through openings provided in insulating layers 106, 218, and 235. Similarly, pixel electrode 111G is electrically connected to the conductive layer 112b of transistor 205G, and pixel electrode 111B is electrically connected to the conductive layer 112b of transistor 205B.

[0593] Each end of pixel electrodes 111R, 111G, and 111B is covered by an insulating layer 237. The insulating layer 237 serves as a partition wall. The insulating layer 237 can be configured as a single layer or a multilayer structure using one or both of inorganic and organic insulating materials. For example, the insulating layer 237 can use materials suitable for insulating layer 218 and insulating layer 235. The insulating layer 237 electrically insulates the pixel electrodes from the common electrode. Furthermore, the insulating layer 237 electrically insulates adjacent light-emitting elements.

[0594] An insulating layer 237 is provided at least in the display section 162. The insulating layer 237 can be provided not only in the display section 162, but also in the connecting section 140 and the circuit section 164. Furthermore, the insulating layer 237 can also be provided to extend to the end of the display device 50A.

[0595] The common electrode 115 is a continuous film shared by the light-emitting elements 130R, 130G, and 130B. The common electrode 115 shared by multiple light-emitting elements is electrically connected to the conductive layer 123 disposed in the connection portion 140. The conductive layer 123 is preferably a conductive layer formed using the same material as the pixel electrodes 111R, 111G, and 111B and through the same process as the pixel electrodes 111R, 111G, and 111B.

[0596] In the display device of one embodiment of the present application, a conductive film that transmits visible light is used as the electrode on the light-extraction side among the pixel electrode and the common electrode. In addition, a conductive film that reflects visible light is preferably used as the electrode on the side where light is not extracted.

[0597] Alternatively, a conductive film that transmits visible light can be used as the electrode on the side where light is not extracted. In this case, the electrode is preferably provided between the reflective layer and the EL layer. In other words, light emission from the EL layer can be reflected by the reflective layer and extracted from the display device.

[0598] As a material of a pair of electrodes that form a light-emitting element, a metal, an alloy, a conductive compound, a mixture thereof, or the like can be appropriately used. Specifically, a metal such as aluminum, magnesium, titanium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, indium, tin, molybdenum, tantalum, tungsten, palladium, gold, platinum, silver, yttrium, and neodymium, and an alloy of these metals can be given. In addition, indium tin oxide (also referred to as In-Sn oxide, ITO), In-Si-Sn oxide (also referred to as ITSO), indium zinc oxide (In-Zn oxide), In-W-Zn oxide, and the like can be given. Further, an alloy containing aluminum such as an alloy of aluminum, nickel, and lanthanum (Al-Ni-La), an alloy of silver and magnesium, an alloy of silver, palladium, and copper (also referred to as Ag-Pd-Cu, APC), and the like can be given. Further, an element belonging to Group 1 or Group 2 in the periodic table (e.g., lithium, cesium, calcium, strontium), a rare earth metal such as europium and ytterbium, an alloy of these elements, graphene, and the like can be given.

[0599] The light-emitting element preferably has a microcavity structure. Thus, one of a pair of electrodes included in the light-emitting element preferably includes an electrode having both a visible light transmitting property and a visible light reflecting property (semi-transmissive-semireflective electrode), and the other preferably includes an electrode having a visible light reflecting property (reflective electrode). When the light-emitting element has a microcavity structure, light emission from the light-emitting layer can be resonated between the two electrodes, and light emitted from the light-emitting element can be enhanced.

[0600] The light transmittance of the transparent electrode is higher than or equal to 40 %. For example, an electrode having a visible light (light with a wavelength of greater than or equal to 400 nm and less than 750 nm) transmittance higher than or equal to 40 % is preferably used as the transparent electrode of the light-emitting element. The visible light reflectance of the semi-transmissive-semireflective electrode is higher than or equal to 10 % and lower than or equal to 95 %, preferably higher than or equal to 30 % and lower than or equal to 80 %. The visible light reflectance of the reflective electrode is higher than or equal to 40 % and lower than or equal to 100 %, preferably higher than or equal to 70 % and lower than or equal to 100 %. Further, the resistivity of these electrodes is preferably lower than or equal to 1 x 10 -2 Ωcm.

[0601] The EL layers 113R, 113G, and 113B are each provided in an island shape. In Figure 21A In the present embodiment, the end portion of the EL layer 113R overlaps with the end portion of the EL layer 113G, the end portion of the EL layer 113G overlaps with the end portion of the EL layer 113B, and the end portion of the EL layer 113R overlaps with the end portion of the EL layer 113B. As shown in Figure 21A In the case where the island-shaped EL layers are deposited using a high-precision metal mask, the end portions of the EL layers adjacent to each other sometimes overlap, but the present application is not limited to this. That is, the EL layers adjacent to each other can also be separated without overlapping. In addition, both the portion where the EL layers adjacent to each other overlap and the portion where the EL layers adjacent to each other are separated without overlapping can exist in the display device.

[0602] The EL layers 113R, 113G, and 113B each include at least a light-emitting layer. The light-emitting layer contains one or more light-emitting substances. As the light-emitting substance, a substance exhibiting a light-emitting color of blue, violet, blue-violet, green, yellow-green, yellow, orange, or red, or the like is appropriately used. In addition, as the light-emitting substance, a substance emitting near-infrared light can also be used.

[0603] As the light-emitting substance, a fluorescent material, a phosphorescent material, a TADF material, and a quantum dot material, or the like can be given.

[0604] The light-emitting layer can contain one or more organic compounds (host material, auxiliary material, or the like) in addition to the light-emitting substance (guest material). As the one or more organic compounds, one or both of a substance having a high hole-transport property (hole-transport material) and a substance having a high electron-transport property (electron-transport material) can be used. In addition, as the one or more organic compounds, a bipolar substance (a substance having a high hole-transport property and a high electron-transport property) or a TADF material can also be used.

[0605] For example, the light-emitting layer preferably contains a combination of a phosphorescent material, a hole-transport material that easily forms an exciplex, and an electron-transport material. By adopting such a structure, luminescence by ExTET (Exciplex-Triplet Energy Transfer) using energy transfer from an exciplex to a light-emitting substance (phosphorescent material) can be efficiently obtained. By selecting a combination of an exciplex that forms light having a wavelength overlapping with an absorption band on the lowest energy side of the light-emitting substance as the exciplex, energy transfer can be made smooth, and thus luminescence can be efficiently obtained. By adopting the above structure, high efficiency, low voltage driving, and long lifetime of the light-emitting element can be simultaneously achieved.

[0606] In addition to the light-emitting layer, the EL layer may also include one or more of the following: a layer containing a material with high hole injection capability (hole injection layer), a layer containing a hole transport material (hole transport layer), a layer containing a material with high electron blocking capability (electron blocking layer), a layer containing a material with high electron injection capability (electron injection layer), a layer containing an electron transport material (electron transport layer), and a layer containing a material with high hole blocking capability (hole blocking layer). Furthermore, the EL layer may also include one or both of a bipolar material and a TADF material.

[0607] Light-emitting elements can use low-molecular-weight compounds or high-molecular-weight compounds, and may also contain inorganic compounds. The layers constituting the light-emitting element can be formed by methods such as vapor deposition (including vacuum vapor deposition), transfer printing, printing, inkjet printing, and coating.

[0608] Light-emitting elements can be either a single structure (a structure with only one light-emitting unit) or a series structure (a structure including multiple light-emitting units). Each light-emitting unit includes at least one light-emitting layer. A series structure has multiple light-emitting units connected in series via a charge-generating layer. The charge-generating layer functions to inject electrons into one of the two light-emitting units and holes into the other when a voltage is applied between a pair of electrodes. By employing a series structure, light-emitting elements capable of emitting light with high brightness can be realized. Furthermore, the series structure improves reliability because it reduces the current required to achieve the same brightness compared to a single structure. Additionally, the series structure can be referred to as a stacked structure.

[0609] exist Figure 21A When using a series-connected light-emitting element, it is preferred that the EL layer 113R includes a plurality of light-emitting units that emit red light, the EL layer 113G includes a plurality of light-emitting units that emit green light, and the EL layer 113B includes a plurality of light-emitting units that emit blue light.

[0610] A protective layer 131 is provided on the light-emitting elements 130R, 130G, and 130B. The protective layer 131 and the substrate 152 are bonded together by an adhesive layer 142. A light-shielding layer 117 is provided on the substrate 152. For example, a solid sealing structure or a hollow sealing structure can be used to seal the light-emitting elements. Figure 21A In this configuration, the space between substrate 152 and substrate 151 is filled with adhesive layer 142, thus employing a solid sealing structure. Alternatively, a hollow sealing structure can be used, where the space is filled with an inert gas (such as nitrogen or argon). In this case, adhesive layer 142 can also be arranged in a manner that does not overlap with the light-emitting element. Furthermore, a resin different from that used for the frame-shaped adhesive layer 142 can be used to fill the space.

[0611] The protective layer 131 is provided at least in the display portion 162, and is preferably provided so as to cover the entire display portion 162. The protective layer 131 is preferably provided so as to cover the connection portion 140 and the circuit portion 164 in addition to the display portion 162. Further, the protective layer 131 is preferably provided so as to extend to an end portion of the display device 50A. On the other hand, in order to electrically connect the FPC 172 and the conductive layer 166, a portion of the connection portion 204 where the protective layer 131 is not provided.

[0612] By providing the protective layer 131 over the light emitting elements 130R, 130G, and 130B, the reliability of the light emitting elements can be improved.

[0613] The protective layer 131 can have a single-layer structure or a stacked-layer structure of two or more layers. Further, there is no limitation on the conductivity of the protective layer 131. As the protective layer 131, at least one of an insulating film, a semiconductive film, and a conductive film can be used.

[0614] When the protective layer 131 includes an inorganic film, the degradation of the light emitting element can be suppressed, such as prevention of oxidation of the common electrode 115, suppression of entry of impurities (moisture, oxygen, and the like) into the light emitting element, and the like, whereby the reliability of the display device can be improved.

[0615] As the protective layer 131, for example, an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, and a nitride oxide insulating film can be used. Specific examples of these inorganic insulating films are described above. In particular, the protective layer 131 preferably includes a nitride insulating film or a nitride oxide insulating film, and more preferably includes a nitride insulating film.

[0616] Further, as the protective layer 131, an inorganic film including ITO, an In-Zn oxide, a Ga-Zn oxide, an Al-Zn oxide, or IGZO, or the like can be used. This inorganic film preferably has a high resistance, and specifically, the inorganic film preferably has a higher resistance than the common electrode 115. This inorganic film can also include nitrogen.

[0617] In the case where light emission of the light emitting element is extracted through the protective layer 131, the protective layer 131 preferably has high visible light transmittance. For example, ITO, IGZO, and aluminum oxide are all inorganic materials with high visible light transmittance, and are thus preferable.

[0618] As the protective layer 131, for example, a stacked-layer structure of an aluminum oxide film and a silicon nitride film over the aluminum oxide film or a stacked-layer structure of an aluminum oxide film and an IGZO film over the aluminum oxide film can be employed. By using this stacked-layer structure, entry of impurities (water and oxygen, and the like) into the EL layer side can be suppressed.

[0619] Further, the protective layer 131 can include an organic film. For example, the protective layer 131 can include both an organic film and an inorganic film. As the organic film that can be used for the protective layer 131, for example, an organic insulating film that can be used for the insulating layer 235 or the like can be given.

[0620] The connection portion 204 is provided in a region of the substrate 151 that does not overlap with the substrate 152. In the connection portion 204, the conductive layer 165 is electrically connected to the FPC 172 through the conductive layer 166 and the connection layer 242. For example, the conductive layer 165 is a conductive layer obtained by processing the same conductive film as the conductive layer 112b. An example is shown in which the conductive layer 166 is a conductive layer obtained by processing the same conductive film as the pixel electrodes 111R, 111G, and 111B. The conductive layer 166 is exposed on the top surface of the connection portion 204. Thus, the connection portion 204 can be electrically connected to the FPC 172 through the connection layer 242.

[0621] The display device 50A is of a top emission type. Light emitted from the light emitting element is emitted to the substrate 152 side. The substrate 152 preferably uses a material having high visible light transmittance. The pixel electrodes 111R, 111G, and 111B include a material that reflects visible light, and the counter electrode (common electrode 115) includes a material that transmits visible light.

[0622] It is preferable that a light-blocking layer 117 be provided on the surface of the substrate 152 on the substrate 151 side. The light-blocking layer 117 can be provided between adjacent light emitting elements, in the connection portion 140 and the circuit portion 164, and the like.

[0623] In addition, a colored layer such as a color filter can be provided on the surface of the substrate 152 on the substrate 151 side or the protective layer 131. When the color filter is provided so as to overlap with the light emitting element, the color purity of light emitted from the pixel can be improved.

[0624] The colored layer is a colored layer that selectively transmits light in a specific wavelength region and absorbs light in other wavelength regions. For example, a red (R) color filter that transmits light in a red wavelength region, a green (G) color filter that transmits light in a green wavelength region, a blue (B) color filter that transmits light in a blue wavelength region, and the like can be used. Each colored layer can use one or more of a metal material, a resin material, a pigment, and a dye. The colored layer is formed at a desired position by a printing method, an inkjet method, an etching method using a photolithography method, or the like.

[0625] Further, various optical members can be arranged on the outer side of the substrate 152 (the side opposite to the side of the substrate 151). As the optical member, for example, a polarizing plate, a phase difference plate, a light diffusion layer (diffusion film or the like), an anti-reflection layer, and a condensing film can be given. Further, on the outer side of the substrate 152, an antistatic film that suppresses the attachment of dust, a film having water repellency that is not easily soiled, a hard coat film that suppresses damage during use, a surface protective layer such as an impact absorbing layer, or the like can be arranged. For example, by providing a glass layer or a silicon dioxide layer (SiO x layer) as the surface protective layer, the surface can be suppressed from being soiled or damaged, and thus is preferable. In addition, as the surface protective layer, DLC (diamond like carbon), aluminum oxide (AlO x ), a polyester-based material, a polycarbonate-based material, or the like can be used. In addition, as the surface protective layer, a material having a high visible light transmittance is preferably used. In addition, a material having a high hardness is preferably used for the surface protective layer.

[0626] The substrate 151 and the substrate 152 can each use glass, quartz, ceramic, sapphire, resin, metal, alloy, a semiconductor, or the like. The substrate on the side from which light is extracted from the light emitting element uses a material that transmits the light. By using a material having flexibility for the substrate 151 and the substrate 152, the flexibility of the display device can be improved, and thus a flexible display can be realized. As at least one of the substrate 151 and the substrate 152, a polarizing plate can be used.

[0627] As the substrate 151 and the substrate 152, a polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), a polyacrylonitrile resin, an acrylic resin, a polyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, a polyamide resin (nylon, aramid, or the like), a polysiloxane resin, a cyclic olefin resin, a polystyrene resin, a polyamide-imide resin, a polyurethane resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polypropylene resin, a polytetrafluoroethylene (PTFE) resin, an ABS resin, and a cellulose nanofiber, or the like can be used.

[0628] In a case where a circularly polarizing plate is overlapped on a display device, a substrate having a high optical isotropy is preferably used as a substrate included in the display device. A substrate having a high optical isotropy has a low birefringence (or a small amount of birefringence). As a film having a high optical isotropy, a cellulose triacetate (TAC, also referred to as triacetyl cellulose) film, a cyclic olefin polymer (COP) film, a cyclic olefin copolymer (COC) film, an acrylic resin film, or the like can be given.

[0629] As the adhesive layer 142, various cured adhesives such as an ultraviolet-cured adhesive, a reaction-cured adhesive, a heat-cured adhesive, and an anaerobic adhesive can be used. As such adhesives, an epoxy resin, an acrylic resin, a silicone resin, a phenol resin, a polyimide resin, an imide resin, a PVC (polyvinyl chloride) resin, a PVB (polyvinyl butyral) resin, an EVA (ethylene-vinyl acetate) resin, and the like can be given. In particular, a material with low moisture permeability such as an epoxy resin is preferably used. In addition, a two-liquid mixed type resin can also be used. Furthermore, an adhesive sheet or the like can also be used.

[0630] As the connection layer 242, an anisotropic conductive film (ACF: Anisotropic Conductive Film), an anisotropic conductive paste (ACP: Anisotropic Conductive Paste), or the like can be used.

[0631] [Display device 50B]

[0632] Figure 21B An example of a cross section of the display portion 162 of the display device 50B is shown. The display device 50B differs from the display device 50A mainly in that a light emitting element including an EL layer 113 shared by light emitting elements and a coloring layer (color filter or the like) are used in each color sub-pixel in the former. Figure 21B The structures shown can be combined Figure 21A The structures shown include a region of the FPC 172, the circuit portion 164, the stack of the substrate 151 to the insulating layer 235 of the display portion 162, the connection portion 140, and the end portion. Note that in the description of the display device below, the same portions as those of the display device described earlier are sometimes omitted.

[0633] Figure 21B The display device 50B shown includes a light emitting element 130R, a light emitting element 130G, a light emitting element 130B, a coloring layer 132R that transmits red light, a coloring layer 132G that transmits green light, and a coloring layer 132B that transmits blue light.

[0634] The light emitting element 130R includes a pixel electrode 111R, an EL layer 113 over the pixel electrode 111R, and a common electrode 115 over the EL layer 113. The light emission of the light emitting element 130R is extracted as red light to the outside of the display device 50B through the coloring layer 132R.

[0635] The light emitting element 130G includes a pixel electrode 111G, an EL layer 113 over the pixel electrode 111G, and a common electrode 115 over the EL layer 113. The light emission of the light emitting element 130G is extracted as green light to the outside of the display device 50B through the coloring layer 132G.

[0636] The light-emitting element 130B includes the pixel electrode 111B, an EL layer 113 over the pixel electrode 111B, and a common electrode 115 over the EL layer 113. Light emission of the light-emitting element 130B is extracted as blue light through the coloring layer 132B to the outside of the display device 50B.

[0637] The light-emitting elements 130R, 130G, and 130B share the EL layer 113 and the common electrode 115. The structure in which subpixels of each color share the EL layer 113 can reduce the number of manufacturing steps, compared to a structure in which each subpixel is provided with a different EL layer.

[0638] For example, Figure 21B The light-emitting elements 130R, 130G, and 130B illustrated in the drawing emit white light. The white light emitted by the light-emitting elements 130R, 130G, and 130B is transmitted through the coloring layers 132R, 132G, and 132B, and thus light of a desired color can be obtained.

[0639] A white light-emitting element preferably includes two or more light-emitting layers. In the case where white light emission is obtained using two light-emitting layers, the light-emitting layers are selected so that each light emission color of the two light-emitting layers is in a complementary color relationship. For example, by making the light emission color of a first light-emitting layer and the light emission color of a second light-emitting layer in a complementary color relationship, a structure in which white light is emitted as a whole of the light-emitting element can be obtained. Further, in the case where white light emission is obtained using three or more light-emitting layers, each light emission color of the three or more light-emitting layers is combined to obtain a structure in which white light is emitted as a whole of the light-emitting element.

[0640] The EL layer 113 preferably includes, for example, a light-emitting layer containing a light-emitting substance that emits blue light and a light-emitting layer containing a light-emitting substance that emits visible light longer in wavelength than blue light. The EL layer 113 preferably includes, for example, a light-emitting layer that emits yellow light and a light-emitting layer that emits blue light. Alternatively, the EL layer 113 preferably includes, for example, a light-emitting layer that emits red light, a light-emitting layer that emits green light, and a light-emitting layer that emits blue light.

[0641] The light-emitting element that emits white light preferably has a tandem structure. Specifically, a two-stage tandem structure including a light-emitting unit that emits yellow light and a light-emitting unit that emits blue light, a two-stage tandem structure including a light-emitting unit that emits red light and a light-emitting unit that emits green light, and a three-stage tandem structure including a light-emitting unit that emits blue light, a light-emitting unit that emits yellow light, yellow-green light, or green light, and a light-emitting unit that emits blue light, a three-stage tandem structure including a light-emitting unit that emits blue light, a light-emitting unit that emits yellow light, yellow-green light, or green light, and a light-emitting unit that emits red light, and the like can be given. For example, as the number of stacked layers and the order of colors of the light-emitting units, a two-stage structure in which B and Y are stacked from the anode side, a two-stage structure in which B and a light-emitting unit X are stacked, a three-stage structure in which B, Y, and B are stacked, and a three-stage structure in which B, X, and B are stacked can be given, and as the number of stacked layers and the order of colors of the light-emitting layers in the light-emitting unit X, a two-layer structure in which R and Y are stacked from the anode side, a two-layer structure in which R and G are stacked, a two-layer structure in which G and R are stacked, a three-layer structure in which G, R, and G are stacked, or a three-layer structure in which R, G, and R are stacked can be given. Alternatively, another layer can be provided between two light-emitting layers.

[0642] Further, by employing a microcavity structure, the light-emitting element of the structure that emits white light sometimes emits light of a specific color such as red, green, or blue.

[0643] Alternatively, for example Figure 21B The light-emitting elements 130R, 130G, and 130B illustrated in FIG. 13A emit blue light. At this time, the EL layer 113 includes one or more light-emitting layers that emit blue light. In the case of the sub-pixel 1 IB that emits blue light, the blue light emitted from the light-emitting element 130B can be extracted. Further, in the case of the sub-pixel 11R that emits red light and the sub-pixel 11G that emits green light, the blue light emitted from the light-emitting element 130R or the light-emitting element 130G can be converted into light of a longer wavelength by a color conversion layer provided between the light-emitting element 130R or the light-emitting element 130G and the substrate 152, and extracted as red light or green light. Further, it is preferable that a color conversion layer be provided between the light-emitting element 130R and the substrate 152 and a coloring layer 132R be provided between the light-emitting element 130G and the substrate 152. Part of the light emitted from the light-emitting element sometimes transmits without conversion by the color conversion layer. By extracting the light that has transmitted the color conversion layer through the coloring layer, light other than the desired color light can be absorbed by the coloring layer, and the color purity of the light emitted by the sub-pixel can be improved.

[0644] [Display device 50C]

[0645] Figure 22 The display device 50C illustrated in FIG. 13C differs from the display device 50B mainly in that the former is a bottom emission type display device.

[0646] Light emitted from the light-emitting element is extracted to the substrate 151 side. The substrate 151 preferably uses a material having high visible light transmittance. On the other hand, there is no limitation on the light transmittance of the material used for the substrate 152.

[0647] A light-blocking layer 117 is preferably formed between the substrate 151 and the transistor. Figure 22 An example is shown in which the light-blocking layer 117 is provided over the substrate 151, the insulating layer 153 is provided over the light-blocking layer 117, and the transistor 205D, the transistor 205R (not shown), the transistor 205G, and the transistor 205B, and the like are provided over the insulating layer 153. Further, the colored layer 132R, the colored layer 132G, and the colored layer 132B are provided over the insulating layer 218, and the insulating layer 235 is provided over the colored layer 132R, the colored layer 132G, and the colored layer 132B.

[0648] The light-emitting element 130R overlapping with the colored layer 132R includes the pixel electrode 111R, the EL layer 113, and the common electrode 115.

[0649] The light-emitting element 130G overlapping with the colored layer 132G includes the pixel electrode 111G, the EL layer 113, and the common electrode 115.

[0650] The light-emitting element 130B overlapping with the colored layer 132B includes the pixel electrode 111B, the EL layer 113, and the common electrode 115.

[0651] Each of the pixel electrodes 111R, 111G, and 111B uses a material having high visible light transmittance. The common electrode 115 preferably uses a material that reflects visible light. Since a metal or the like having low resistance can be used for the common electrode 115 in a bottom emission display device, a voltage drop due to the resistance of the common electrode 115 can be suppressed, and high display quality can be achieved.

[0652] The transistor of one embodiment of the present application can be miniaturized to reduce the occupied area, and thus the aperture ratio of a pixel can be increased or the size of a pixel can be reduced in a bottom emission display device.

[0653] [Display device 50D]

[0654] Figure 23A The display device 50D shown differs from the display device 50A mainly in that the former includes the light-receiving element 130S.

[0655] The display device 50D includes a light-emitting element and a light-receiving element in a pixel. In the display device 50D, it is preferable that an organic EL element be used as the light-emitting element and an organic photodiode be used as the light-receiving element. The organic EL element and the organic photodiode can be formed on the same substrate. Thus, the organic photodiode can be mounted in a display device using an organic EL element.

[0656] In the display device 50D in which a pixel includes a light-emitting element and a light-receiving element, the pixel has a light-receiving function, so the display device can detect contact or proximity of an object while displaying an image. Thus, the display portion 162 has one or both of an imaging function and a sensing function in addition to an image display function. For example, not only an image is displayed in all sub-pixels included in the display device 50D, but also a part of the sub-pixels can emit light as a light source, another part of the sub-pixels can detect light, and the remaining sub-pixels can display an image.

[0657] Thus, a light-receiving portion and a light source do not need to be separately provided from the display device 50D, so the number of components of an electronic device can be reduced. For example, a biometric identification device mounted in an electronic device or an electrostatic capacitance touch panel used for scrolling or the like does not need to be separately provided. Thus, by using the display device 50D, an electronic device with reduced manufacturing cost can be provided.

[0658] When a light-receiving element is used for an image sensor, the display device 50D can capture an image using the light-receiving element. For example, an image sensor can be used for imaging for personal identification using a fingerprint, a palm print, an iris, a pulse shape (including a vein shape and an artery shape), or a face.

[0659] In addition, the light-receiving element can be used for a touch sensor (also referred to as a direct touch sensor) or a non-contact sensor (also referred to as a hovering sensor, a hovering touch sensor, or a non-touch sensor). The touch sensor can detect an object (a finger, a hand, a pen, or the like) when the object directly contacts the display device. In addition, the non-contact sensor can detect an object even when the object does not contact the display device.

[0660] The light-emitting element 130S includes a pixel electrode 111S over an insulating layer 235, a functional layer 113S over the pixel electrode 111S, and a common electrode 115 over the functional layer 113S. Light Lin is incident on the functional layer 113S from the outside of the display device 50D.

[0661] The pixel electrode 111S is electrically connected to a conductive layer 112b included in the transistor 205S through an opening portion provided in the insulating layer 106, the insulating layer 218, and the insulating layer 235.

[0662] An end portion of the pixel electrode 111S is covered with an insulating layer 237.

[0663] The common electrode 115 is a continuous film shared by the light-receiving element 130S, the light-emitting element 130R (not shown), the light-emitting element 130G, and the light-emitting element 130B. The common electrode 115 shared by the light-emitting element and the light-receiving element is electrically connected to the conductive layer 123 provided in the connection portion 140.

[0664] The functional layer 113S includes at least an active layer (also referred to as a photoelectric conversion layer). The active layer contains a semiconductor. As the semiconductor, an inorganic semiconductor such as silicon and an organic semiconductor containing an organic compound can be given. In this embodiment, an example in which an organic semiconductor is used as the semiconductor contained in the active layer is shown. By using an organic semiconductor, the light-emitting layer and the active layer can be formed in the same method (e.g., a vacuum evaporation method), and manufacturing equipment can be used in common, and thus is preferable.

[0665] The functional layer 113S can also include a layer containing a substance having a high hole-transport property, a substance having a high electron-transport property, or a bipolar substance, or the like, as a layer other than the active layer. In addition, it is not limited thereto, and can also include a layer containing a substance having a high hole-injection property, a hole-blocking material, a substance having a high electron-injection property, or an electron-blocking material, or the like. As the functional layer 113S, a material described above that can be used for a light-emitting element can be used, for example.

[0666] The light-receiving element can use a low molecular compound or a high molecular compound, and can also contain an inorganic compound. The layers constituting the light-receiving element can be formed by a method such as an evaporation method (including a vacuum evaporation method), a transfer method, a printing method, an inkjet method, a coating method, or the like.

[0667] Figure 23B and Figure 23C The display device 50D shown in FIG. 17 includes a layer 353 including a light-receiving element, a circuit layer 355, and a layer 357 including a light-emitting element between the substrate 151 and the substrate 152.

[0668] The layer 353 includes the light-receiving element 130S, for example. The layer 357 includes the light-emitting elements 130R, 130G, and 130B, for example.

[0669] The circuit layer 355 includes a circuit that drives the light-receiving element and a circuit that drives the light-emitting element. The circuit layer 355 includes the transistors 205R, 205G, and 205B, for example. In addition to this, one or a plurality of a switch, a transistor, a capacitor, a resistor, a wiring, a terminal, and the like can be provided in the circuit layer 355.

[0670] Figure 23B is an example in which the light-receiving element 130S is used as a touch sensor. As Figure 23BAs shown, when the finger 352 touching the display device 50D reflects the light emitted from the light emitting element in the layer 357, the light receiving element in the layer 353 detects the reflected light. Thus, it is possible to detect that the finger 352 is touching the display device 50D.

[0671] Figure 23C The light receiving element 130S is an example of a non-contact sensor. As shown, when the finger 352 approaching (i.e., not touching) the display device 50D reflects the light emitted from the light emitting element in the layer 357, the light receiving element in the layer 353 detects the reflected light. Figure 23C

[0672] [Display device 50E]

[0673] Figure 24A The display device 50E shown is an example of a display device employing an MML (Metal Mask Less) structure. That is, the display device 50E includes light emitting elements manufactured without using a high-precision metal mask.

[0674] The island-shaped light emitting layer in the light emitting element included in the display device employing the MML structure is formed by processing using photolithography after depositing the light emitting layer on the entire surface. Thus, it is possible to realize a high-definition display device or a display device with a high aperture ratio, which has been difficult to realize so far. Further, since the light emitting layer can be formed separately for each color, it is possible to realize a display device that is extremely bright, has a high contrast, and has high display quality. For example, when using three types of light emitting elements that emit blue light, green light, and red light to constitute the display device, it is possible to form three types of island-shaped light emitting layers by repeating deposition of the light emitting layer and processing using photolithography three times.

[0675] Since the device of the MML structure can be manufactured without using a metal mask, it is possible to exceed the upper limit of the definition due to the alignment precision of the metal mask. Further, when manufacturing the device without using the metal mask, it is possible to omit the equipment related to the manufacture of the metal mask and the cleaning process of the metal mask. Further, in the processing using photolithography, it is possible to use the same device as or the same device as used when manufacturing the transistor, so it is not necessary to introduce a special device for manufacturing the device of the MML structure. Thus, the MML structure can reduce the manufacturing cost, so it is suitable for mass production of the device.

[0676] In the display device employing the MML structure, for example, it is not necessary to employ a special pixel arrangement such as a Pentile arrangement to improve the definition in a pseudo manner, so it is possible to realize a display device in which a so-called stripe arrangement in which sub-pixels of R, G, and B are arranged in one direction is employed and the definition is high (e.g., 500 ppi or higher, 1000 ppi or higher, 2000 ppi or higher, 3000 ppi or higher, or 5000 ppi or higher).​

[0677] Further, by providing the sacrificial layer on the light-emitting layer, damage to the light-emitting layer in the manufacturing process of the display device can be reduced, and the reliability of the light-emitting element can be improved.

[0678] Further, by employing the deposition process using a range mask and the processing process using a resist mask, the light-emitting element can be manufactured with a simple process.

[0679] Note that the stack structure of the substrate 151 to the insulating layer 235 and the stack structure of the protective layer 131 to the substrate 152 are the same as those of the display device 50A, and thus the description thereof is omitted.

[0680] In the display device 50B, the light-emitting elements 130R, 130G, and 130B are provided over the insulating layer 235. Figure 24A

[0681] The light-emitting element 130R includes the conductive layer 124R over the insulating layer 235, the conductive layer 126R over the conductive layer 124R, the layer 133R over the conductive layer 126R, the common layer 114 over the layer 133R, and the common electrode 115 over the common layer 114. Figure 24A The light-emitting element 130R illustrated emits red light (R). The layer 133R includes a light-emitting layer which emits red light. In the light-emitting element 130R, the layer 133R and the common layer 114 can be collectively referred to as an EL layer. One or both of the conductive layer 124R and the conductive layer 126R can be referred to as a pixel electrode.

[0682] The light-emitting element 130G includes the conductive layer 124G over the insulating layer 235, the conductive layer 126G over the conductive layer 124G, the layer 133G over the conductive layer 126G, the common layer 114 over the layer 133G, and the common electrode 115 over the common layer 114. Figure 24A The light-emitting element 130G illustrated emits green light (G). The layer 133G includes a light-emitting layer which emits green light. In the light-emitting element 130G, the layer 133G and the common layer 114 can be collectively referred to as an EL layer. One or both of the conductive layer 124G and the conductive layer 126G can be referred to as a pixel electrode.

[0683] The light-emitting element 130B includes the conductive layer 124B over the insulating layer 235, the conductive layer 126B over the conductive layer 124B, the layer 133B over the conductive layer 126B, the common layer 114 over the layer 133B, and the common electrode 115 over the common layer 114. Figure 24A The light-emitting element 130B illustrated emits blue light (B). The layer 133B includes a light-emitting layer which emits blue light. In the light-emitting element 130B, the layer 133B and the common layer 114 can be collectively referred to as an EL layer. One or both of the conductive layer 124B and the conductive layer 126B can be referred to as a pixel electrode.​

[0684] In this specification and the like, an island-shaped layer provided for each light emitting element in an EL layer included in a light emitting element is referred to as a layer 133R, a layer 133G, or a layer 133B, and a layer common to a plurality of light emitting elements is referred to as a common layer 114. Note that in this specification and the like, the layer 133R, the layer 133G, and the layer 133B which do not include the common layer 114 are sometimes referred to as an island-shaped EL layer, an EL layer formed in an island shape, or the like.

[0685] The layer 133R, the layer 133G, and the layer 133B are separated from each other. By providing an island-shaped EL layer in each light emitting element, a leakage current between adjacent light emitting elements can be suppressed. Thus, unintended light emission due to crosstalk can be suppressed, and a display device with a very high contrast ratio can be achieved.

[0686] Further, in Figure 24A , the film thicknesses of the layers 133R, 133G, and 133B are shown to be the same thickness, but they are not limited thereto. Each of the thicknesses of the layers 133R, 133G, and 133B can be different.

[0687] The conductive layer 124R is electrically connected to the conductive layer 112b included in the transistor 205R through an opening portion provided in the insulating layer 106, the insulating layer 218, and the insulating layer 235. Similarly, the conductive layer 124G is electrically connected to the conductive layer 112b included in the transistor 205G, and the conductive layer 124B is electrically connected to the conductive layer 112b included in the transistor 205B.

[0688] The conductive layers 124R, 124G, and 124B are formed so as to cover the opening portions provided in the insulating layer 235. The recesses of the conductive layers 124R, 124G, and 124B are each filled with the layer 128.

[0689] The layer 128 has a function of planarizing the recesses of the conductive layers 124R, 124G, and 124B. The conductive layers 126R, 126G, and 126B electrically connected to the conductive layers 124R, 124G, and 124B are provided over the conductive layers 124R, 124G, and 124B and the layer 128. The conductive layer 124R and the conductive layer 126R are preferably conductive layers used as a reflective electrode.

[0690] Here, the layers 133R, 133G, and 133B are formed by photolithography. Thus, in the case where the layer 128 is not used and the conductive layers 126R, 126G, and 126B are not provided, a film that becomes the layers 133R, 133G, and 133B is also formed in the recesses of the conductive layers 124R, 124G, and 124B. At this time, the film in the recesses can not be etched and remain as a residue. Thus, it is preferable to planarize the formed surfaces of the layers 133R, 133G, and 133B with the layer 128 and the conductive layers 126R, 126G, and 126B.

[0691] In addition, in the display device 50E, the portions where the layer 128 is provided are covered with the insulating layers 125 and 127, but the application is not limited thereto. As shown in the display device 50F described later, the portions where the layer 128 is provided are not covered with the insulating layers 125 and 127, and the regions overlapping with the recesses of the conductive layers 124R, 124G, and 124B can also be used as light emitting regions, whereby the aperture ratio of the pixels can be improved.

[0692] The layer 128 can be an insulating layer or a conductive layer. The layer 128 can be appropriately formed using various inorganic insulating materials, organic insulating materials, and conductive materials. In particular, the layer 128 is preferably formed using an insulating material, and more preferably formed using an organic insulating material. As the layer 128, for example, an organic insulating material that can be used for the insulating layer 237 described above can be used.

[0693] Although Figure 24A An example in which the top surface of the layer 128 has a flat portion is shown, but the shape of the layer 128 is not particularly limited. The top surface of the layer 128 can have at least one of a convex curved surface, a concave curved surface, and a flat surface.

[0694] In addition, the height of the top surface of the layer 128 can be the same or substantially the same as the height of the top surface of the conductive layer 124R, or can be different from the height of the top surface of the conductive layer 124R. For example, the height of the top surface of the layer 128 can be lower or higher than the height of the top surface of the conductive layer 124R.

[0695] The end portion of the conductive layer 126R can also be aligned with the end portion of the conductive layer 124R, and can also cover the side surface of the end portion of the conductive layer 124R. Each of the end portions of the conductive layer 124R and the conductive layer 126R preferably has a tapered shape. Specifically, each of the end portions of the conductive layer 124R and the conductive layer 126R preferably has a tapered shape having a taper angle of greater than 0 degrees and less than 90 degrees. When the end portion of the pixel electrode has a tapered shape, the layer 133R provided along the side surface of the pixel electrode has an inclined portion. By providing the side surface of the pixel electrode with a tapered shape, the coverage of the EL layer provided along the side surface of the pixel electrode can be made good.

[0696] The conductive layers 124G, 126G, 124B, and 126B are the same as the conductive layers 124R and 126R, so detailed descriptions are omitted.

[0697] The top and side surfaces of conductive layer 126R are covered by layer 133R. Similarly, the top and side surfaces of conductive layer 126G are covered by layer 133G, and the top and side surfaces of conductive layer 126B are covered by layer 133B. Therefore, the entire area where conductive layers 126R, 126G, and 126B are disposed can be used as the light-emitting area of ​​light-emitting elements 130R, 130G, and 130B, thereby improving the pixel aperture ratio.

[0698] A portion of the top surface and side surface of each of layers 133R, 133G, and 133B are covered by insulating layers 125 and 127. A common layer 114 is disposed on layers 133R, 133G, 133B, and insulating layers 125 and 127, and a common electrode 115 is disposed on the common layer 114. Both the common layer 114 and the common electrode 115 are continuous films shared by multiple light-emitting elements.

[0699] exist Figure 24A In the middle, there is no space between conductive layer 126R and layer 133R. Figure 21A The insulating layer 237 is shown. In other words, the display device 50E does not have an insulating layer (also called a separator, dam, spacer, etc.) that contacts the pixel electrodes and covers the top surface of the pixel electrodes. Therefore, the spacing between adjacent light-emitting elements can be very small. This allows for a high-definition or high-resolution display device. Furthermore, a mask for forming this insulating layer is not required, thereby reducing the manufacturing cost of the display device.

[0700] As described above, layers 133R, 133G, and 133B all include a light-emitting layer. Preferably, layers 133R, 133G, and 133B include a light-emitting layer and a carrier transport layer (electron transport layer or hole transport layer) on the light-emitting layer. Alternatively, layers 133R, 133G, and 133B preferably include a light-emitting layer and a carrier blocking layer (hole blocking layer or electron blocking layer) on the light-emitting layer. Alternatively, layers 133R, 133G, and 133B may also include a light-emitting layer, a carrier blocking layer on the light-emitting layer, and a carrier transport layer on the carrier blocking layer. Since the surfaces of layers 133R, 133G, and 133B are exposed during the manufacturing process of the display device, by providing one or both of the carrier transport layer and the carrier blocking layer on the light-emitting layer, the exposure of the light-emitting layer to the outermost surface can be suppressed, thereby reducing damage to the light-emitting layer. This improves the reliability of the light-emitting element.

[0701] The common layer 114 includes, for example, an electron injection layer or a hole injection layer. Alternatively, the common layer 114 can have a stack of an electron transport layer and an electron injection layer, or a stack of a hole transport layer and a hole injection layer.

[0702] Note that when the layer 133R, the layer 133G, and the layer 133B include a light-emitting layer, a carrier transport layer over the light-emitting layer, and a carrier injection layer (a hole injection layer or an electron injection layer) over the carrier transport layer, the common layer 114 can not be provided. In that case, the common electrode 115 is provided in contact with the layer 133R, the layer 133G, the layer 133B, the insulating layer 127, the insulating layer 125, and the like.

[0703] Each side surface of the layer 133R, the layer 133G, and the layer 133B is covered with the insulating layer 125. The insulating layer 127 covers each side surface of the layer 133R, the layer 133G, and the layer 133B with the insulating layer 125 interposed therebetween.

[0704] By covering the side surfaces of the layer 133R, the layer 133G, a...

Claims

1. A semiconductor device, comprising: Semiconductor layer; First conductive layer; Second conductive layer; Third conductive layer; First insulating layer; as well as Second insulating layer, The first insulating layer is located on the first conductive layer. The second conductive layer is located on the first insulating layer. The semiconductor layer is in contact with the top surface of the first conductive layer, the top surface and side surface of the second conductive layer, and the side surface of the first insulating layer. The second insulating layer is located on the semiconductor layer. The third conductive layer is located on the second insulating layer and overlaps with the semiconductor layer through the second insulating layer. The semiconductor layer includes a first region that contacts the top surface of the first conductive layer and a second region that contacts the top surface of the second conductive layer. The first region and the second region contain the first element. Furthermore, the first element is boron or phosphorus.

2. A semiconductor device, comprising: Semiconductor layer; First conductive layer; Second conductive layer; Third conductive layer; First insulating layer; as well as Second insulating layer, The first insulating layer is located on the first conductive layer and has a first opening. The second conductive layer is located on the first insulating layer and has a second opening that overlaps with the first opening. The semiconductor layer is in contact with the top surface of the first conductive layer through the first opening and the second opening, and is also in contact with the top surface of the second conductive layer, the side surface of the second opening, and the side surface of the first opening of the first insulating layer. The second insulating layer is located on the semiconductor layer. The third conductive layer is located on the second insulating layer and overlaps with the semiconductor layer through the second insulating layer. The semiconductor layer includes a first region that contacts the top surface of the first conductive layer and a second region that contacts the top surface of the second conductive layer. The first region and the second region contain the first element. Furthermore, the first element is boron or phosphorus.

3. The semiconductor device according to claim 2, The substrate includes the first insulating layer. Furthermore, the angle formed between the side surface of the first opening in the first insulating layer and the top surface of the substrate is 65 degrees or more and 90 degrees or less.

4. The semiconductor device according to any one of claims 1 to 3, The second insulating layer contains the first element.

5. The semiconductor device according to any one of claims 1 to 3, The first region and the second region contain hydrogen. And the first element is boron.

6. The semiconductor device according to any one of claims 1 to 3, The semiconductor layer includes a third region that contacts the side of the first insulating layer. The first region includes areas with a higher concentration of the first element compared to the third region. Furthermore, the second region includes a region with a higher concentration of the first element compared to the third region.

7. The semiconductor device according to claim 6, The first region includes areas with a higher hydrogen concentration compared to the third region. Furthermore, the second region includes areas with a higher hydrogen concentration compared to the third region.

8. The semiconductor device according to any one of claims 1 to 3, The semiconductor layer contains metal oxide in the channel formation region.

9. The semiconductor device according to any one of claims 1 to 3, The first insulating layer comprises a first layer containing nitrogen and silicon on the first conductive layer, a second layer containing oxygen and silicon on the first layer, and a third layer containing nitrogen and silicon on the second layer.

10. The semiconductor device according to claim 9, The first insulating layer includes a fourth layer located between the first conductive layer and the first layer, and a fifth layer on the third layer. The fourth layer includes regions with a higher hydrogen content compared to the first layer. Furthermore, the fifth layer includes regions containing more hydrogen compared to the third layer.

11. The semiconductor device of claim 9, further comprising: The third insulating layer, The first conductive layer is located on the third insulating layer. The first insulating layer includes a fourth layer on top of the third layer. The third insulating layer includes regions with a higher hydrogen content compared to the first layer. Furthermore, the fourth layer includes regions containing more hydrogen compared to the third layer.

12. A method for manufacturing a semiconductor device, comprising the following steps: A first conductive layer is formed on the substrate; An insulating film is formed on the first conductive layer; A conductive film is formed on the insulating film; By processing the insulating film and the conductive film, a first insulating layer having a first opening reaching the first conductive layer and a second conductive layer having a second opening overlapping the first opening are formed. A metal oxide layer is formed on the first conductive layer, the second conductive layer and the first insulating layer; A second insulating layer is formed on the metal oxide layer; The first element is supplied to the metal oxide layer through the second insulating layer; as well as A third conductive layer is formed on the second insulating layer. The first element is boron or phosphorus.

13. The method for manufacturing a semiconductor device according to claim 12, In the process of supplying the first element, plasma ion doping or ion implantation is used.

14. The method for manufacturing a semiconductor device according to claim 12, In the process of supplying the first element, no quality separation is performed.

15. The method for manufacturing a semiconductor device according to claim 12, Hydrogen is supplied along with the first element.

16. The method for manufacturing a semiconductor device according to claim 12, The first element is supplied from a direction perpendicular or substantially perpendicular to the top surface of the substrate.

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