Device manufacturing method and inorganic light-emitting element

Abstract

To provide a semiconductor device including an inorganic light-emitting element.SOLUTION: A semiconductor device includes an inorganic light-emitting element, a transistor, and a capacitor. The inorganic light-emitting element includes a first film and a second film. The first film contains indium, oxygen, and nitrogen, and the second film contains gallium and nitrogen. The first film has a wurtzite structure or a cubic crystal structure, and the second film has a wurtzite structure and grows on the first film. The first film functions as a cathode electrode of the inorganic light-emitting element. One electrode of the capacitor is formed above the second film included in the inorganic light-emitting element, and a transistor including a metal oxide in a semiconductor layer is formed above the other electrode of the capacitor. The one electrode of the capacitor has a function of reflecting light emitted from the inorganic light-emitting element. The inorganic light-emitting element emits light through the first film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a semiconductor device including a metal nitride film and a metal nitride film formed on a metal oxynitride film, and also to an inorganic light-emitting element, a lighting device, a display device, an electronic device, and a semiconductor device including the metal nitride film.

[0002] In this specification and the like, a semiconductor device refers to any device that can function by utilizing semiconductor characteristics. Semiconductor elements such as transistors, as well as semiconductor circuits, arithmetic devices, and memory devices are all embodiments of semiconductor devices. Display devices (such as liquid crystal display devices and light-emitting display devices), projection devices, lighting devices, electro-optical devices, power storage devices, memory devices, semiconductor circuits, imaging devices, communication devices, electronic devices, and the like may be considered to include semiconductor devices.

[0003] Note that one aspect of the present invention is not limited to the above technical fields. One aspect of the invention disclosed in this specification relates to an object, a method, or a manufacturing method. Another aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. [Background technology]

[0004] Nitride semiconductors containing Group 13 elements (such as gallium) are known as constituent materials for inorganic light-emitting devices, power semiconductor devices, and communication devices. Patent Document 1 discloses a method for producing nitride semiconductors.

[0005] Metal oxynitrides containing metal, oxygen, and nitrogen are known as pigments and photocatalytic materials. Metal oxynitrides are also attracting attention as semiconductor materials and insulating materials used in semiconductor devices. Patent Document 2 discloses a semiconductor material containing a metal oxynitride containing indium, gallium, and zinc.

[0006] Furthermore, epitaxial growth is known as a method for forming an in-plane oriented thin film (also called a single-crystal thin film). Here, in-plane orientation refers to the regularity of the crystal orientation in the horizontal direction relative to the substrate. Patent Document 3 discloses a method for forming a single-crystal InGaO3(ZnO)5 thin film by reactive solid-phase epitaxy. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2005 / 6420 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-18929 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-103957 Summary of the Invention [Problem to be solved by the invention]

[0008] The nitride semiconductor fabrication method disclosed in Patent Document 1 uses pulsed laser deposition (PLD). The PLD method is a film formation method that utilizes laser ablation and requires a laser and an optical system. Another issue is that there is a large difference in the deposition rate of the thin film between the front of the plasma (plume) induced in the target by laser irradiation and other areas. Therefore, it is difficult to mass-produce thin films using the PLD method.

[0009] Furthermore, the metal oxynitride disclosed in Patent Document 2 is in an amorphous state in which the bonds between atoms are disordered. Amorphous metal oxynitrides have pores or low-density regions, which reduces the stability of the metal oxynitride. Metal oxynitrides used in semiconductor devices and the like preferably have high crystallinity. In particular, it is preferable that the metal oxynitride be in-plane oriented.

[0010] Furthermore, the reactive solid-phase epitaxial method disclosed in Patent Document 3 has the problem of requiring high-temperature treatments, such as heating the substrate to 1000°C or higher before depositing the InGaO3(ZnO)5 thin film, and then performing a thermal diffusion treatment at 1300°C or higher after depositing the thin film. Furthermore, to form a single-crystal InGaO3(ZnO)5 thin film, an epitaxially grown ZnO thin film must be provided on the substrate. Thus, there are various limitations to forming an epitaxially grown thin film using conventional techniques. In this specification, high temperatures refer to temperatures of, for example, 700°C or higher, and low temperatures refer to temperatures of, for example, 600°C or lower.

[0011] In view of the above, an object of one embodiment of the present invention is to provide an inorganic light-emitting element or the like using a metal nitride film formed by epitaxial growth on a metal oxynitride film. Another object of one embodiment of the present invention is to increase the productivity of inorganic light-emitting elements or the like using a metal nitride film. Another object of one embodiment of the present invention is to provide a method for forming a metal oxynitride film by epitaxial growth at low temperature. Another object of one embodiment of the present invention is to provide a method for forming a metal oxynitride film by epitaxial growth without performing high-temperature treatment before or after the formation of the metal oxynitride film. Another object of one embodiment of the present invention is to provide a method for forming a metal nitride film by epitaxial growth on a metal oxynitride film without performing high-temperature treatment.

[0012] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these will become apparent from the description of the specification, drawings, claims, etc., and it is possible to extract other problems from the description of the specification, drawings, claims, etc. [Means for solving the problem]

[0013] An inorganic light-emitting element according to one embodiment of the present invention includes a first film (metal oxynitride film) and a second film (metal nitride film). The first film includes indium and oxygen, and the second film includes gallium and nitrogen. The second film has a wurtzite structure. The first film can function as a cathode electrode of the inorganic light-emitting element. Preferably, the first film further includes gallium, zinc, and nitrogen.

[0014] Another embodiment of the present invention provides a semiconductor device including an inorganic light-emitting element, a transistor, and a capacitor. The inorganic light-emitting element includes a first film (metal oxynitride film) and a second film (metal nitride film). The first film includes indium and oxygen, and the second film includes gallium and nitrogen. The second film has a wurtzite structure. One electrode of the capacitor is formed above the second film of the inorganic light-emitting element, and a transistor is formed above the other electrode of the capacitor. The one electrode of the capacitor has a function of reflecting light emitted by the inorganic light-emitting element, and the inorganic light-emitting element can emit light through the first film. The transistor preferably includes a metal oxide in a semiconductor layer, and the semiconductor layer of the transistor preferably includes indium, gallium, zinc, and oxygen.

[0015] Another embodiment of the present invention is a method for forming a first film. The first film can be epitaxially grown on a substrate by sputtering using an oxide target after introducing a gas containing nitrogen gas onto the substrate. The first film is preferably an in-plane oriented film. The oxide target contains zinc and is conductive. The substrate temperature during the formation of the first film is 80°C or higher and 500°C or lower, and the flow rate of nitrogen gas is 50% or higher and 100% or lower of the total flow rate of the gas. The oxide target preferably further contains indium and gallium.

[0016] In the above, the substrate is preferably a single-crystal yttria-stabilized zirconia (YSZ) substrate with a (111) plane orientation, or a single-crystal a-plane sapphire substrate with a (110) plane orientation.

[0017] Another embodiment of the present invention is a method for forming a second film. The second film can be epitaxially grown on the first film by sputtering using a nitride target after introducing a gas containing nitrogen gas. The second film is preferably an in-plane oriented film. The nitride target contains gallium and nitrogen and is conductive. The substrate temperature during deposition of the metal nitride film is 80°C or higher and 500°C or lower, and the flow rate of nitrogen gas is 80% or higher and 100% or lower of the total flow rate of the gas.

[0018] In the above, when a φ scan is performed in X-ray analysis on the (101) plane of the crystal of the first film and the second film, it is preferable that a diffraction peak showing six-fold symmetry is observed for the first film and the second film. Furthermore, the smaller the full width at half maximum (sometimes called Δφ) of the φ scan in X-ray diffraction, the better the in-plane orientation. [Effects of the Invention]

[0019] According to one aspect of the present invention, an inorganic light-emitting device or the like can be provided that uses a metal nitride film formed by epitaxial growth on a metal oxynitride film. Furthermore, according to one aspect of the present invention, the productivity of an inorganic light-emitting device or the like that uses a metal nitride film can be increased. Furthermore, according to one aspect of the present invention, a method for forming a metal oxynitride film by epitaxial growth at low temperature can be provided. Furthermore, according to one aspect of the present invention, a method for forming a metal oxynitride film by epitaxial growth without performing high-temperature treatment before or after the metal oxynitride film formation can be provided. Furthermore, according to one aspect of the present invention, a method for forming a metal nitride film by epitaxial growth on a metal oxynitride film without performing high-temperature treatment can be provided.

[0020] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0021] [Figure 1] Fig. 1A is a diagram illustrating a metal oxynitride film epitaxially grown on a substrate, Fig. 1B is a diagram illustrating the crystal planes of the crystals in the metal oxynitride film, and Fig. 1C is a diagram illustrating the atomic arrangement of the crystals. [Figure 2] FIG. 2 is a diagram illustrating a metal oxynitride film epitaxially grown on a substrate. [Figure 3] FIG. 3 is a diagram illustrating the range of the atomic ratio of metals constituting the oxide target. [Figure 4] FIG. 4 is a schematic diagram illustrating a sputtering apparatus. [Figure 5] Figure 5 shows the experimental layout for X-ray measurements. [Figure 6] 6A to 6C are diagrams illustrating the intensity distribution obtained by pole figures and pole measurements. [Figure 7] FIG. 7 is a diagram showing a configuration example of an inorganic light-emitting element. [Figure 8] FIG. 8 is a diagram illustrating an example of the configuration of a display device. [Figure 9] 9A and 9B are diagrams showing examples of the configuration of a transistor. [Figure 10] 10A to 10C are diagrams showing examples of the configuration of a transistor. [Figure 11] 11A to 11C are diagrams showing examples of the configuration of a transistor. [Figure 12] FIG. 12 is a diagram illustrating an example of the configuration of a display device. [Figure 13] 13A to 13C are diagrams showing configuration examples of a display device. [Figure 14] FIG. 14 is a diagram illustrating an example of the configuration of a display device. [Figure 15] 15A and 15B are diagrams illustrating configuration examples of electronic devices. [Figure 16] 16A to 16E are diagrams showing configuration examples of electronic devices. [Figure 17] FIG. 17 is a diagram showing the results of X-ray analysis of the sample of the example. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments will be described with reference to the drawings. However, it will be readily understood by those skilled in the art that the embodiments can be implemented in many different ways and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the following embodiments.

[0023] In addition, in the drawings, sizes, layer thicknesses, or regions may be exaggerated for clarity. Therefore, the drawings are not necessarily limited to the scale. The drawings are schematic representations of ideal examples and are not limited to the shapes or values ​​shown in the drawings. For example, in actual manufacturing processes, layers, resist masks, etc. may be unintentionally thinned by processes such as etching, but this may not be reflected in the drawings to facilitate understanding. In addition, in the drawings, the same symbols are used for identical parts or parts having similar functions across different drawings, and repeated explanations may be omitted. When referring to similar functions, the same hatch pattern may be used and no particular symbol may be assigned.

[0024] In order to make the invention easier to understand, particularly in top views (also called "plan views") and perspective views, some components may be omitted from the drawings. Also, some hidden lines may be omitted from the drawings.

[0025] Furthermore, in this specification, terms indicating arrangement such as "above" and "below" are used for convenience in describing the positional relationship between components with reference to the drawings. Furthermore, the positional relationship between components changes as appropriate depending on the direction in which each component is depicted. Therefore, the terms are not limited to those described in the specification, and can be rephrased appropriately depending on the situation.

[0026] For example, if it is explicitly stated in this specification that X and Y are connected, it is assumed that the specification also discloses cases in which X and Y are electrically connected, cases in which X and Y are functionally connected, and cases in which X and Y are directly connected. Therefore, it is not limited to a specific connection relationship, for example, a connection relationship shown in a figure or text, and it is assumed that connections other than those shown in a figure or text are also disclosed in a figure or text. Here, X and Y are assumed to be objects (e.g., devices, elements, circuits, wiring, electrodes, terminals, conductive films, layers, etc.).

[0027] In this specification and the like, a transistor is an element having at least three terminals including a gate, a drain, and a source. A transistor has a region (hereinafter also referred to as a channel formation region) where a channel is formed between the drain (drain terminal, drain region, or drain electrode) and the source (source terminal, source region, or source electrode), and a current can flow between the source and the drain through the channel formation region. In this specification and the like, the channel formation region refers to a region through which a current mainly flows.

[0028] Furthermore, the functions of the source and drain may be interchanged when transistors of different polarities are used, when the direction of current flow changes during circuit operation, etc. For this reason, in this specification and the like, the terms source and drain may be used interchangeably.

[0029] In this specification and the like, the term "insulator" can be replaced with "insulating film," the term "conductor" can be replaced with "conductive film," and the term "semiconductor" can be replaced with "semiconductor film" or "semiconductor layer."

[0030] Furthermore, in this specification, "parallel" refers to a state in which two straight lines are arranged at an angle of -10° or more and 10° or less. Therefore, it also includes cases where the angle is -5° or more and 5° or less. Furthermore, "substantially parallel" refers to a state in which two straight lines are arranged at an angle of -30° or more and 30° or less. Furthermore, "perpendicular" refers to a state in which two straight lines are arranged at an angle of 80° or more and 100° or less. Therefore, it also includes cases where the angle is 85° or more and 95° or less. Furthermore, "substantially perpendicular" refers to a state in which two straight lines are arranged at an angle of 60° or more and 120° or less.

[0031] In this specification, crystal planes are represented using Miller indices. Miller indices are represented by three integers in parentheses. The direction of the arrangement of crystal planes (the direction perpendicular to the crystal plane) is called the crystal orientation. The crystal orientation is represented by three integers in square brackets. For example, a crystal plane is represented as (111), and a crystal orientation is represented as

[0111] . In addition, a notation called Miller-Bravais indices is sometimes used in hexagonal crystal systems. Specifically, the plane index of a hexagonal crystal lattice is represented as (hkil) using four integers (h, k, i, l), where i = -(h + k). Because the index i can be calculated from the values ​​of the indexes h and k, in this specification, the crystal planes of a hexagonal crystal system are also represented as Miller indices (hkl) using three integers. Furthermore, in crystallography, crystal planes, directions, and space groups are represented by placing a superscript bar over the numbers. However, in this specification and other documents, due to limitations on application notation, numbers may be represented by placing a minus sign (-) before them instead of placing a bar over them.

[0032] In this specification, the crystal plane appearing on the surface of the single crystal substrate may be referred to as the plane orientation of the single crystal substrate.

[0033] In this specification, lattice points in a reciprocal lattice (also called reciprocal lattice points) corresponding to crystal planes are expressed by indices without parentheses.

[0034] (Embodiment 1) In this embodiment, a method for forming a metal nitride film used in an inorganic light-emitting element according to one embodiment of the present invention will be described.

[0035] Metal nitrides containing metal and nitrogen have attracted attention as semiconductor materials and insulating materials for use in semiconductor devices. Metal nitrides used in semiconductor devices preferably have few impurities and defects and are highly stable. A metal nitride with few impurities and defects can be said to have high crystallinity. A metal nitride with high stability refers to a metal nitride that is unlikely to react with materials in contact with the metal nitride due to heat generated during operation of the semiconductor device, that the crystallinity of the metal nitride does not change, or that defects are unlikely to occur in the metal nitride. Using a metal nitride with few impurities and defects and high stability in a semiconductor device can improve the reliability of the semiconductor device.

[0036] In one embodiment of the present invention, a metal oxynitride film can be provided as a buffer layer between a substrate and a metal nitride to form a highly crystalline metal nitride film with few impurities and defects. In order to form a highly crystalline metal nitride film, it is preferable to provide a metal oxynitride film with few impurities and defects.

[0037] Impurities in metal oxynitrides refer to, for example, elements other than the main components constituting the metal oxynitride. For example, elements with a concentration of less than 0.1 atomic % in metal oxynitrides can be considered impurities. Examples of such elements include hydrogen, silicon, boron, phosphorus, carbon, and transition metals other than the main components constituting the metal oxynitride. Furthermore, defects in metal oxynitrides refer to lattice defects, and examples of lattice defects include point defects such as oxygen vacancies and nitrogen vacancies, line defects such as dislocations, and planar defects such as grain boundaries. Furthermore, defects in metal oxynitrides include void defects such as porosity.

[0038] Furthermore, from the viewpoint of crystallinity, thin films are classified into in-plane oriented thin films, oriented thin films, non-oriented thin films (polycrystalline thin films), and non-crystalline thin films (amorphous thin films). An oriented thin film is a thin film in which at least one crystal axis of the crystals contained in the thin film is aligned in a specific direction. An in-plane oriented thin film is a thin film in which three crystal axes of the crystals contained in the thin film are aligned in specific directions.

[0039] A metal oxynitride thin film used in a semiconductor device or the like preferably has orientation, and more preferably is an in-plane oriented metal oxynitride thin film. An in-plane oriented metal oxynitride thin film has few impurities and defects and a dense structure. Therefore, by using an in-plane oriented metal oxynitride thin film in a semiconductor device or the like, the reliability of the semiconductor device or the like can be improved.

[0040] Epitaxial growth is known as a method for forming in-plane oriented thin films. Epitaxial growth refers to the growth of crystals constituting a thin film on a single crystal substrate with a specific crystal orientation relationship. Growth of a crystal on a single crystal substrate using the same material as the substrate and with the same lattice constant as the crystal of the substrate is called homoepitaxial growth. Growth of a crystal on a single crystal substrate using a material different from the substrate or a material with a lattice constant different from that of the crystal of the substrate is called heteroepitaxial growth. Heteroepitaxial growth is possible by selecting a material with a small lattice mismatch with the crystal of the substrate, or by providing a layer (also called a buffer layer) that relieves lattice distortion between the substrate and the thin film.

[0041] Epitaxial growth methods include solid phase epitaxy (SPE), liquid phase epitaxy (LPE), and vapor phase epitaxy (VPE).

[0042] SPE is a method in which the material to be deposited on the substrate surface is heated by electron beam irradiation or other methods to change the material to the same crystalline structure as the substrate's crystals. LPE is a method in which crystalline portions are precipitated on the substrate surface from a supersaturated solution. VPE is a method in which components in the gas phase are deposited on the substrate surface. VPE methods include pulsed laser deposition (PLD), atomic layer deposition (ALD), and molecular beam epitaxy (MBE). MBE is a method in which elements or materials containing elements that make up the target crystal are heated and evaporated in an ultra-high vacuum, and the crystal is deposited on the heated substrate.

[0043] Conventional techniques impose various constraints on epitaxial growth of thin films. These constraints include, for example, forming the thin film at a high temperature, performing a heat treatment at a high temperature (e.g., 1000°C or higher) after forming the thin film, performing a planarization treatment on the substrate surface before forming the thin film, providing one or more buffer layers on the substrate, or selecting substrates with similar lattice constants or thermal expansion coefficients. Examples of planarization treatment of the substrate surface include performing a heat treatment on the substrate at a high temperature.

[0044] Therefore, in a method for forming a metal oxynitride film according to one embodiment of the present invention, a metal oxynitride film is epitaxially grown at a low temperature. In this method, a gas is introduced into a reaction chamber and the metal oxynitride film is epitaxially grown on a single crystal substrate by sputtering. In one embodiment of the present invention, the epitaxial growth can form a film with in-plane orientation.

[0045] The crystal structure of the metal oxynitride film to be epitaxially grown is preferably a hexagonal crystal structure. Among hexagonal crystal structures, a wurtzite structure is particularly preferable. The wurtzite structure has a crystal orientation relationship that allows epitaxial growth with cubic crystal structures (e.g., diamond structure, fluorite structure, zinc blende structure, etc.). For example, the

[0111] direction of a cubic crystal and the

[0001] direction of a wurtzite structure have a crystal orientation relationship that allows epitaxial growth. Therefore, a metal oxynitride film having a hexagonal crystal structure can be easily epitaxially grown on a single-crystal substrate having a crystal structure such as a cubic or hexagonal crystal structure. Furthermore, a material having a crystal structure such as a cubic or hexagonal crystal structure can be easily epitaxially grown on the metal oxynitride film.

[0046] In addition to the above-mentioned hexagonal crystal structure, it is preferable that the crystal structure of the metal oxide thin film to be epitaxially grown is a cubic crystal structure. Among cubic crystal structures, a bixbyite (C-type rare earth) structure is particularly preferable. The cubic crystal system has a crystal orientation relationship with the hexagonal crystal system that allows epitaxial growth. As described above, the

[0111] direction of the cubic crystal and the

[0001] direction of the wurtzite structure have a crystal orientation relationship that allows epitaxial growth, so that a metal nitride film having a hexagonal crystal structure can be easily epitaxially grown on the metal oxide thin film having a cubic crystal structure.

[0047] The single crystal substrate may be an insulating substrate such as a sapphire substrate or a stabilized zirconia substrate (e.g., an yttria-stabilized zirconia (YSZ) substrate). When the metal oxynitride has a wurtzite crystal structure, it is preferable to use, for example, a YSZ substrate with a (111) crystal orientation or an a-plane sapphire substrate with a (110) crystal orientation as the substrate. Using a YSZ substrate or an a-plane sapphire substrate as the substrate facilitates the formation of a thin film of a metal oxynitride having a wurtzite crystal structure and an in-plane orientation. Substrates such as silicon, germanium, silicon carbide, gallium nitride, gallium arsenide, indium phosphide, and zinc oxide may also be used.

[0048] The difference between the lattice constant of the epitaxially grown thin film and that of the substrate (also known as lattice mismatch) is preferably small. By reducing the lattice mismatch, it becomes easier to epitaxially grow a thin film on a single crystal substrate.

[0049] One way to evaluate the degree of lattice mismatch is to use the lattice mismatch ratio. The lattice mismatch ratio Δa is the ratio of the lattice constant a of the epitaxially grown thin film crystal. e and the lattice constant a of the substrate crystal s and is calculated using the following formula (1).

[0050]

number

[0051] The lattice mismatch between the metal oxynitride film to be epitaxially grown and the single crystal substrate is preferably 15% or less, more preferably 10% or less, which makes it easier to epitaxially grow the metal oxynitride film on the single crystal substrate.

[0052] When a metal oxynitride film having a wurtzite structure crystal is epitaxially grown on a cubic single crystal substrate, for example, the substrate has a

[0111] orientation, while the metal oxynitride film has a

[0001] orientation, and therefore the crystal orientations are different.s The lattice mismatch can be calculated by multiplying the root of half by two times the lattice constant of the crystal of the substrate. Specifically, when a YSZ substrate with a lattice constant in the a-axis direction of approximately 0.51 nm is used as the single crystal substrate, the distance between nearest neighboring atoms as viewed from the

[0111] direction is approximately 0.36 nm at the smallest. Therefore, in consideration of the above-mentioned preferable range of lattice mismatch, the lattice constant in the a-axis direction of the crystal of the metal oxynitride film is preferably 0.31 nm to 0.41 nm, and more preferably 0.32 nm to 0.40 nm.

[0053] Furthermore, in a method for forming a metal nitride film according to one embodiment of the present invention, a metal nitride film is epitaxially grown at low temperature on a metal oxynitride film or a metal oxide film. For example, when a metal nitride film is epitaxially grown on a metal oxynitride film at low temperature, a gas is introduced into a reaction chamber and the metal nitride film is epitaxially grown on the metal oxynitride film by a sputtering method. In one embodiment of the present invention, a film with in-plane orientation can be formed by epitaxial growth.

[0054] The crystal structure of the epitaxially grown metal nitride film is preferably a hexagonal crystal structure. Among hexagonal crystal structures, a wurtzite structure is particularly preferred. Because the epitaxially grown metal oxynitride film has a wurtzite structure, it is easy to grow a metal nitride film having a wurtzite structure on the metal oxynitride film.

[0055] For example, a metal nitride film epitaxially grown on a metal oxynitride film epitaxially grown on a YSZ substrate with a (111) crystal orientation or an a-plane sapphire substrate with a (110) crystal orientation will have higher crystallinity than a metal nitride film epitaxially grown on a YSZ substrate with a (111) crystal orientation or an a-plane sapphire substrate with a (110) crystal orientation. While high temperatures are typically required for epitaxial growth, this method does not require high temperatures for epitaxial growth. Furthermore, metal oxynitride films can be easily formed using sputtering.

[0056] Since the epitaxially grown metal oxynitride film has a wurtzite structure, the metal oxynitride film functions as a good buffer layer that alleviates the lattice mismatch between the substrate and the metal nitride film. When the metal oxynitride film and the metal nitride film are used in semiconductor devices, the metal nitride film preferably has high crystallinity.

[0057] As an example, when an inorganic light-emitting device is formed using a metal nitride, the metal nitride film has at least an n-type cladding layer, an active layer, and a p-type cladding layer. Therefore, in order to stack metal nitride films, it is preferable that the metal nitride film on the buffer layer has higher crystallinity than the buffer layer. Higher crystallinity improves the uniformity of the carrier concentration and other properties in the metal nitride film, thereby improving electrical characteristics. Furthermore, higher crystallinity can improve the breakdown voltage and current reliability of the inorganic light-emitting device. In a second embodiment, a detailed description is given of an example of fabricating an inorganic light-emitting device or display device using a metal oxynitride film and a metal nitride film.

[0058] Note that semiconductor devices using metal oxynitride films and metal nitride films are not limited to display elements and display devices, but can also be applied to projection devices, lighting devices, electro-optical devices, power storage devices, memory devices, semiconductor circuits, imaging devices, communication devices, electronic devices, and the like.

[0059] FIG. 1A shows a schematic diagram of a structure including a metal oxynitride film epitaxially grown on a single-crystal substrate. FIG. 1A is a schematic diagram of a structure in which a metal oxynitride film 20 is formed on a single-crystal substrate 10. FIG. 1A illustrates a case in which the metal oxynitride film 20 has crystals 20a with a wurtzite structure. According to a fabrication method of one embodiment of the present invention, the metal oxynitride film 20 is epitaxially grown such that the c-axis (

[0001] direction) of the wurtzite structure crystals 20a coincides with the normal direction to the surface of the single-crystal substrate 10. Here, a film epitaxially grown by a fabrication method of one embodiment of the present invention is sometimes referred to as a c-axis epitaxial film because the c-axis (

[0001] direction) of the crystals contained in the film coincides with the normal direction to the surface of the single-crystal substrate. The normal direction may also be referred to as the vertical direction.

[0060] The crystal planes of the wurtzite structure will be explained using Figure 1B. Figure 1B shows typical crystal planes ((001) plane, (101) plane) of the wurtzite structure. The (001) plane of the wurtzite structure shown in Figure 1B is a plane parallel to the surface of the single-crystal substrate 10.

[0061] Figure 1C shows the atomic configurations in the wurtzite structure. In Figure 1C, configuration X1 is the configuration of metal atoms, and configuration X2 is the configuration of oxygen atoms or nitrogen atoms. Note that configuration X1 may be the configuration of oxygen atoms or nitrogen atoms, and configuration X2 may be the configuration of metal oxide atoms.

[0062] The sputtering target used in the sputtering method is preferably an oxide target containing zinc, and more preferably an oxide target containing zinc and at least one of indium and gallium. Examples of the oxide target that can be used include a zinc oxide target, an indium zinc oxide (In-Zn oxide) target, a gallium zinc oxide (Ga-Zn oxide) target, and an indium gallium zinc oxide (In-Ga-Zn oxide) target. In particular, an indium gallium zinc oxide target is preferably used as the oxide target. The crystal structures of indium nitride, gallium nitride, and zinc oxide are all wurtzite structures. Therefore, by using such an oxide target for film formation, it is easy to form a thin film of a metal oxynitride having a wurtzite structure and an in-plane orientation. Note that even when a non-wurtzite oxide target is used, the thin film formed may have a wurtzite structure.

[0063] As another example, the sputtering target used in the sputtering method is preferably an oxide target containing indium, and more preferably an oxide target containing indium and tin. Examples of the oxide target that can be used include an indium oxide target and an indium tin oxide (ITO) target. Generally, the crystal structure of both indium oxide and indium tin oxide is a bixbyite (C-type rare earth) structure. Therefore, by using such an oxide target for film formation, it becomes easier to form a thin film of a metal oxide having a bixbyite-type structure crystal and an in-plane orientation.

[0064] 2 is a schematic diagram of a structure including a metal nitride film 30 epitaxially grown on a metal oxynitride film 20 having a wurtzite structure. The metal nitride film 30 has crystals 30a with a wurtzite structure. The (001) plane of the wurtzite structure of the metal oxynitride film 20 is parallel to the crystal plane on which the metal nitride film 30 epitaxially grows, improving the crystallinity of the metal nitride film 30. The metal nitride film 30 preferably contains at least a Group 13 element and a Group 15 element.

[0065] A preferred range of the atomic ratio of metals constituting the zinc-containing oxide target will be described with reference to Fig. 3. Fig. 3 is a diagram showing the atomic ratio of indium, gallium, and zinc contained in the oxide target. Note that Fig. 3 does not show the atomic ratio of oxygen. The atomic ratios of indium, gallium, and zinc contained in the oxide target are represented by [In], [Ga], and [Zn], respectively.

[0066] In Figure 3, the dashed lines represent the line where the atomic ratio of [In]:[Ga]:[Zn] = (1 + α):(1 - α):1 (α is a real number between -1 and 1), the line where the atomic ratio of [In]:[Ga]:[Zn] = (1 + α):(1 - α):2, the line where the atomic ratio of [In]:[Ga]:[Zn] = (1 + α):(1 - α):3, and the line where the atomic ratio of [In]:[Ga]:[Zn] = (1 + α):(1 - α):4.

[0067] In addition, the dotted lines represent the line where the atomic ratio of [In]:[Ga]:[Zn]=4:1:β (β is a real number greater than or equal to zero), the line where the atomic ratio of [In]:[Ga]:[Zn]=2:1:β, the line where the atomic ratio of [In]:[Ga]:[Zn]=1:1:β, the line where the atomic ratio of [In]:[Ga]:[Zn]=1:2:β, and the line where the atomic ratio of [In]:[Ga]:[Zn]=1:4:β.

[0068] Region A in Figure 3 shows an example of a preferred range of the atomic ratio of indium, gallium, and zinc in the oxide target. Region A includes In-Ga-Zn oxide targets with [In]:[Ga]:[Zn]=4:2:4.1 and [In]:[Ga]:[Zn]=1:1:1, an In-Zn oxide target with [In]:[Ga]:[Zn]=2:0:1 ([In]:[Zn]=2:1), and a zinc oxide target with [In]:[Ga]:[Zn]=0:0:1.

[0069] The sputtering target used in the sputtering method is not limited to an oxide target, but may be an oxynitride target, such as an indium gallium zinc oxynitride (In-Ga-Zn oxynitride) target or an indium gallium oxynitride (In-Ga oxynitride) target.

[0070] The substrate temperature during deposition of the metal oxynitride film is preferably from room temperature (25° C.) to 500° C., more preferably from 80° C. to 400° C., and even more preferably from 150° C. to 350° C. Since the film can be deposited at a substrate temperature of 500° C. or less, the productivity of semiconductor devices and the like using the metal oxynitride film can be improved.

[0071] A gas containing nitrogen gas is preferably used as the gas introduced into the reaction chamber during the deposition of the metal oxynitride film. For example, nitrogen gas, a mixed gas of nitrogen gas and oxygen gas, or a mixed gas of nitrogen gas and a rare gas (argon, helium, etc.) is preferably used as the gas. Here, the flow rate of nitrogen gas is preferably 50% to 100% of the total flow rate of the gas, more preferably 70% to 100%, and even more preferably 85% to 100%. The composition of the resulting metal oxynitride film can be adjusted by adjusting the flow rate ratio of nitrogen gas to the total flow rate of the gas.

[0072] <Sputtering equipment> Next, a sputtering apparatus for forming a metal oxynitride film according to one embodiment of the present invention will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view illustrating a film formation chamber 201 included in a sputtering apparatus 200.

[0073] The film formation chamber 201 shown in FIG. 4 includes a substrate holder 202, a sputtering target 204, a backing plate 205, and a magnet unit 206. One or more magnet units 206 (e.g., magnet unit 206a, magnet unit 206b) can be provided. The magnet unit 206 can be fixed or have a swing mechanism. The sputtering target 204 is disposed and fixed on the backing plate 205. The magnet unit 206 is disposed below the sputtering target 204 via the backing plate 205. When a substrate 203 is loaded into the film formation chamber 201, the substrate 203 is disposed in contact with the substrate holder 202. The film formation chamber 201 also includes an intake port 210a and an exhaust port 210b for supplying a gas (also referred to as a film formation gas). A film forming gas is supplied to the film forming chamber 201 through an intake port 210a, and the film forming gas is exhausted through an exhaust port 210b.

[0074] 4 shows an example in which magnet unit 206a and magnet unit 206b are provided. Magnet unit 206a and magnet unit 206b have a swing mechanism, with magnet unit 206a having swing range 207a and magnet unit 206b having swing range 207b. A uniform film can be formed by swinging magnet unit 206a and magnet unit 206b in the range in which sputtering target 204 is placed. For example, magnet unit 206a or magnet unit 206b may be swung at a beat (which may also be referred to as rhythm, time signature, pulse, frequency, period, cycle, etc.) of 0.1 Hz to 1 kHz.

[0075] The magnetic field that the sputtering target 204 receives is determined by the voltage V2 applied to the substrate holder 202 and the voltage V1 applied to the backing plate 205. The magnetic field that the sputtering target 204 receives also changes as the magnet unit 206 swings. A region with a strong magnetic field becomes a high-density plasma region, and therefore, sputtering of the sputtering target 204 is likely to occur in the vicinity of the region. When the sputtering target 204 contains multiple elements, the magnetic field strength applied to the sputtering target 204 from the magnet unit 206a can be different from the magnetic field strength applied to the sputtering target 204 from the magnet unit 206b. Elements corresponding to the magnetic field strength are deposited on the substrate 203.

[0076] 4 shows an example in which a parallel plate sputtering apparatus is used, but the method for forming a metal oxynitride film according to the present embodiment is not limited to this. For example, a facing target sputtering apparatus may be used to form a metal oxynitride film.

[0077] Sputtering allows film formation at low temperatures, and therefore can increase the productivity of semiconductor devices and the like that use the metal oxynitride film.

[0078] One embodiment of the present invention can provide a method for forming a metal oxynitride film by epitaxial growth at low temperature. Another embodiment of the present invention can provide a method for forming a metal oxynitride film by epitaxial growth without performing high-temperature treatment before or after the formation of the metal oxynitride film. Another embodiment of the present invention can provide a method for forming a metal nitride film by epitaxial growth on a metal oxynitride film without performing high-temperature treatment. Another embodiment of the present invention can provide a semiconductor device or the like using a metal nitride film formed by epitaxial growth on a metal oxynitride film. Another embodiment of the present invention can improve the productivity of a semiconductor device or the like using a metal nitride film.

[0079] <Method for evaluating the crystallinity and orientation of thin films> The evaluation of the epitaxial growth can be performed during or after the thin film is formed, depending on the evaluation method.

[0080] Examples of methods for evaluating epitaxial growth during thin film formation include Reflection High Energy Electron Diffraction (RHEED) and Surface Photoabsorption (SPA).

[0081] Furthermore, the epitaxial growth (crystallinity and orientation) of the deposited thin film can be evaluated by combining a transmission electron microscope (TEM) and X-ray diffraction (XRD) methods, including reciprocal space mapping, pole measurement (φ scan), out-of-plane measurement, and in-plane measurement.

[0082] The following describes measurement methods that can be used to evaluate the crystallinity and orientation of thin films.

[0083] <Reciprocal space mapping> Reciprocal space mapping will now be described.

[0084] Reciprocal space is a space formed by the fundamental vectors of reciprocal space (also called reciprocal vectors), and reflects the periodicity of real space. Here, the reciprocal lattice vector b j is the fundamental vector of the real space lattice a i and are related by the following mathematical formula (1): In other words, the planes defined in the crystal in real space are treated as lattice points in the reciprocal lattice.

[0085]

number

[0086] An epitaxially grown thin film has little variation in the crystal orientation of the crystals that make up the thin film, i.e., has a high degree of orientation. Therefore, when a reciprocal lattice space map is acquired for an epitaxially grown thin film, the intensity of the observed spot is high and the full width at half maximum (FWHM) of the spot is small. On the other hand, when a reciprocal lattice space map is acquired for a thin film with large variation in the crystal orientation of the crystals, i.e., with low orientation, the intensity of the observed spot is low and the full width at half maximum of the spot is large. From the above, the crystallinity and orientation of a thin film can be evaluated by acquiring a reciprocal lattice space map.

[0087] An apparatus that can be used for X-ray analysis will be described using Figure 5. As shown in Figure 5, when viewing the X-ray analysis apparatus from above, the direction in which the X-ray source, sample, and detector are aligned is defined as the ψ axis. When viewing the X-ray analysis apparatus from above, the direction perpendicular to the ψ axis is defined as the θ axis. The direction perpendicular to the ψ axis and the θ axis is defined as the φ axis. In other words, the φ axis is parallel to the direction in which the X-ray analysis apparatus is viewed from above. Note that the axis referred to as the ψ axis in this specification may be referred to as the χ axis in some apparatuses. Therefore, the ψ axis can also be referred to as the χ axis. Similarly, the axis referred to as the θ axis in this specification may be referred to as the ω axis in some apparatuses. Therefore, the θ axis can also be referred to as the ω axis.

[0088] A two-dimensional detector may be used as the detector. The two-dimensional detector has position information in the 2θ and χ directions on the detection surface. The detector shown in FIG. 5 is shown as a replica of a two-dimensional detector. Unless otherwise specified, values ​​used in this specification use CuKα radiation (wavelength: 0.15418 nm) as the X-ray source.

[0089] <Pole measurement> Pole measurement is a method for measuring the distribution of diffraction intensity by rotating the sample in all directions while keeping the positions (angles) of the X-ray source and detector constant.

[0090] In addition, an analysis in which a specific crystal plane of a sample is scanned in the φ direction is called a φ scan, and a small full width at half maximum (sometimes called Δφ) in a φ scan is considered to have good in-plane orientation. In addition, this in-plane orientation is sometimes referred to as crystallinity in the specification.

[0091] The diffraction intensity obtained by pole measurement will be described with reference to FIG. 6. The diffraction intensity obtained by pole measurement is represented by a polar figure. FIG. 6A shows a polar figure. As shown in FIG. 6A, the center P0 of the polar figure has an angle ψ of 0°, and the outer periphery P1 of the polar figure has an angle ψ of 90°. Furthermore, a line extending directly upward from the center P0 of the polar figure toward the outer periphery P1 of the polar figure (the line indicated by the dashed dotted line P0-P2 in FIG. 6A) has an angle ψ of 0°, and the angle between this line and a line extending from the center P0 of the polar figure toward the outer periphery P1 of the polar figure (the line indicated by the dashed dotted line P0-P3 in FIG. 6A) is the angle ψ. Note that FIG. 6A illustrates that the angle ψ increases with counterclockwise rotation, but this is not limited thereto. Depending on the device, the angle ψ may increase with clockwise rotation. Furthermore, depending on the range of the ψ scan, the angle of the pole figure obtained by pole measurement may not be within the range of 0° to 90°. Note that in pole measurement, the axis referred to as ψ in this specification may be referred to as α depending on the device. Therefore, ψ can also be rephrased as α. Similarly, the axis referred to as φ in this specification may be referred to as β depending on the device. Therefore, θ can also be rephrased as β.

[0092] 6B and 6C show schematic diagrams of diffraction intensity obtained by pole measurement. Fig. 6B shows a schematic diagram of diffraction intensity when a spot-like intensity distribution is observed on concentric circles of angle ψ (circles indicated by dashed lines in the figure), and Fig. 6C shows a schematic diagram of diffraction intensity when a ring-like intensity distribution is observed.

[0093] For example, the (101) plane of the wurtzite-type structure has six-fold symmetry. That is, when performing pole figure measurement on a c-axis epitaxial thin film having a wurtzite-type structure crystal, as shown in Fig. 6B, six spot-like intensity distributions (diffraction peaks) are observed on a concentric circle at a certain angle ψ. Therefore, when a thin film having a wurtzite-type structure crystal grows epitaxially on the c-axis, a diffraction peak showing six-fold symmetry is observed in the pole figure measurement or φ scan of the (101) plane of the crystal of the thin film. Specifically, diffraction peaks are observed at intervals of about 60° on a concentric circle where the angle ψ is about 62°.

[0094] On the other hand, when performing pole figure measurement on a non-epitaxially grown thin film, a ring-like intensity distribution as shown in Fig. 6C is observed, or no diffraction peak is observed. Therefore, by analyzing the intensity distribution observed in the pole figure measurement, it is possible to evaluate whether the thin film is epitaxially grown.

[0095] In addition, in the pole figure measurement or φ scan of the (220) plane of a single-crystal YSZ substrate, a diffraction peak showing three-fold symmetry is observed. Specifically, diffraction peaks are observed at intervals of about 120° on a concentric circle where the angle ψ is about 35°. Also, in the pole figure measurement or φ scan of the (300) plane of a single-crystal a-plane sapphire substrate, a diffraction peak showing two-fold symmetry is observed. Specifically, diffraction peaks are observed at intervals of about 180° on a concentric circle where the angle ψ is about 30°.

[0096] <Out-of-plane measurement and In-plane measurement> In the measurement using the XRD method, there are Out-of-plane measurement and In-plane measurement. Out-of-plane measurement is a method for evaluating a crystal plane parallel to the surface of the thin film, and In-plane measurement is a method for evaluating a crystal plane perpendicular to the surface of the thin film. In Out-of-plane measurement and In-plane measurement, a 0-dimensional detector may be used as the detector.

[0097] The structures, methods, and the like described in this embodiment can be used in appropriate combination with structures, methods, and the like described in other embodiment modes and examples.

[0098] (Embodiment 2) In this embodiment, the use of the epitaxially grown metal oxynitride film shown in the previous embodiment will be described.

[0099] The metal oxynitride film can be used in, for example, inorganic light-emitting devices, light-receiving devices, power semiconductor devices, and semiconductor devices. It is particularly preferred to use it in inorganic light-emitting devices. Examples of inorganic light-emitting devices include LEDs (Light Emitting Diodes) and micro LEDs.

[0100] A structural example of an inorganic light-emitting element using the above-described metal oxynitride film will be described with reference to Fig. 7. Note that in this embodiment, an inorganic light-emitting element having a double heterojunction will be described. However, one embodiment of the present invention is not limited thereto, and an inorganic light-emitting element having a quantum well junction may also be used.

[0101] FIG. 7 illustrates an inorganic light-emitting device 100 using a metal nitride film formed on a metal oxynitride film according to one embodiment of the present invention. As shown in FIG. 7, the inorganic light-emitting device 100 includes a substrate 10, a buffer layer formed of a metal oxynitride film 20, an n-type cladding layer 31, an active layer 32, a p-type cladding layer 33, an electrode 35, and an electrode 36. The n-type cladding layer 31, the active layer 32, and the p-type cladding layer 33 can be formed of metal nitride films. A conductor 34 may be provided between the p-type cladding layer 33 and the electrode 36. The metal oxynitride film 20 is conductive and functions as an electrode of the inorganic light-emitting device 100. As an example, the inorganic light-emitting device 100 uses the metal oxynitride film 20 as a cathode electrode and the conductor 34 as an anode electrode.

[0102] The n-type cladding layer 31, which is a metal nitride film, can be in ohmic contact with the electrode 35 via the metal oxynitride film 20. The p-type cladding layer 33, which is a metal nitride film, can be in ohmic contact with the electrode 36 via the conductor 34.

[0103] The active layer 32 is sandwiched between an n-type cladding layer 31 and a p-type cladding layer 33. In the active layer 32, electrons and holes combine to emit light. In other words, the active layer 32 can be called a light-emitting layer. For example, the n-type cladding layer 31 preferably contains silicon, germanium, tin, or the like as an n-type dopant. The p-type cladding layer 33 preferably contains magnesium, or the like as a p-type dopant. The active layer 32 preferably contains indium, zinc, silicon, or the like.

[0104] By appropriately selecting the atomic ratio of the metals constituting the metal oxynitride film 20 according to one embodiment of the present invention, the dopant added to the metal nitride film, the flow rate of nitrogen gas introduced into the reaction chamber during film formation, etc., it is possible to adjust the conductivity (or insulating property), band gap, optical transparency, etc. of the metal oxynitride film 20 and the metal nitride film. For example, the higher the flow rate of the nitrogen gas, the higher the crystallinity and conductivity of the film tend to be.

[0105] Furthermore, the metal oxynitride film 20 can function as a buffer layer for epitaxially growing a metal nitride thin film thereon. This can improve the crystallinity of the n-type cladding layer 31, active layer 32, and p-type cladding layer 33 formed on the metal oxynitride film 20. The crystal structure of the metal nitride film is hexagonal, like the metal oxynitride film 20, and in particular, is a wurtzite crystal structure. Therefore, it is preferable to use a material that forms a wurtzite crystal structure, such as gallium nitride or an indium gallium nitride compound, for the n-type cladding layer 31 or active layer 32 formed on the metal oxynitride film 20.

[0106] As described above, the metal oxynitride film 20 functions as a buffer layer for hexagonal crystal growth and also functions as an electrode. Using the metal oxynitride film 20 as a buffer layer facilitates epitaxial growth of the n-type cladding layer 31 or active layer 32, and improves the crystallinity of the n-type cladding layer 31 or active layer 32. This improves the properties of the inorganic light-emitting device, such as luminous efficiency and durability.

[0107] FIG. 8 illustrates a structural example of a semiconductor device. The semiconductor device includes an inorganic light-emitting element, a transistor, and a capacitor. Therefore, in one embodiment of the present invention, a structural example in which the semiconductor device is applied to a pixel of a display device will be described. Note that the display device described in FIG. 8 can be applied to a lighting device. By using the inorganic light-emitting element that is one embodiment of the present invention, a display device with high emission efficiency and high reliability can be manufactured.

[0108] The pixel includes an inorganic light-emitting element 100, a transistor 92, and a capacitor 95. The inorganic light-emitting element 100 is formed on a substrate 10 via a metal oxynitride film 20. The inorganic light-emitting element 100 is configured by forming an n-type cladding layer 31, an active layer 32, a p-type cladding layer 33, and a conductor 34 in this order on the metal oxynitride film 20.

[0109] A capacitor 95 is formed on the conductor 34, and a transistor 92 is formed on the capacitor 95. A substrate 11 is provided on the rear side of the substrate 10 opposite to the surface on which the inorganic light-emitting element 100 is formed, with a functional layer 12 interposed therebetween. The functional layer 12 preferably has one or both of a coloring layer and a color conversion layer that differ for each pixel. The functional layer 12 is preferably disposed at a position overlapping the pixel. The functional layer 12 has functional layers 12a to 12c, and the areas of the functional layers 12a to 12c that overlap with the pixel are determined by the light-shielding layer 13.

[0110] In FIG. 8, an example in which a pixel has one transistor is shown for ease of illustration, but the number of transistors is not limited to one. Multiple transistors can be arranged in a position overlapping with a capacitor. Note that a transistor can also be arranged in a position overlapping with an inorganic light-emitting element and a capacitor. For example, a pixel may have a configuration including multiple transistors.

[0111] The insulator 41 is formed so as to cover the inorganic light-emitting element 100. Therefore, it is preferable that the insulator 41 be in contact with the conductor 34 and the metal oxynitride film 20. The conductor 52 is formed on the insulator 41. The conductor 52 functions as one of the electrodes of the capacitor 95. The conductor 52 is electrically connected to the conductor 34 through an opening in the insulator 41 formed on the inorganic light-emitting element 100. The conductor 52 also functions as a reflective film that reflects light emitted by the inorganic light-emitting element 100.

[0112] The insulator 43 is formed on the conductor 52. The insulator 43 is preferably in contact with the insulator 41 and the metal oxynitride film 20. The conductor 54 is formed on the insulator 43. The conductor 54 functions as the other electrode of the capacitor 95. Therefore, the capacitor 95 is formed in a region where the conductor 54 overlaps with the conductor 52 with the insulator 43 interposed therebetween.

[0113] The insulator 47 is formed on the conductor 54. Preferably, the insulator 47 is in contact with the insulator 43. Preferably, the insulator 47 is a colored layer. Preferably, the colored layer reduces transmission of light emitted from the inorganic light-emitting element 100.

[0114] Conductor 52 and conductor 54 can be made of a metal film containing an element selected from molybdenum, titanium, tantalum, tungsten, aluminum, silver, copper, chromium, neodymium, or scandium, or a metal nitride film containing any of the above elements (tantalum nitride film, titanium nitride film, molybdenum nitride film, tungsten nitride film). Alternatively, conductive materials such as indium tin oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, or indium tin oxide with added silicon oxide can also be used. It is preferable to use a metal film with high reflectivity (aluminum, an alloy containing aluminum, silver, or the like) for conductor 52.

[0115] For example, the inorganic light-emitting element 100 emits light L1 to light L5. When the substrate 11 serves as a display surface of a display device, light L1 emitted from the inorganic light-emitting element 100 can contribute to display. Light L2 to light L5 are emitted toward the capacitor 95. Light L2 is emitted from the display surface because one of the electrodes of the capacitor 95 serves as a reflective film. However, light L3 reflected by the reflective film is reduced by the light-shielding layer 13 from emitting toward the display surface. The inclusion of the light-shielding layer 13 prevents light L3 reflected by the reflective film from emitting through the functional layer 12b of an adjacent pixel. Furthermore, light L4 and light L5 reflected by the reflective film can prevent the emitted light from mixing with adjacent pixels. Therefore, the insulator 47 can maintain the purity and brightness of the light emitted by a pixel and reduce the influence of light emitted by other pixels.

[0116] In order to improve the flatness, the top surface of the insulator 47 is preferably planarized by planarization treatment using a chemical mechanical polishing (CMP) method or the like. A transistor 92 is formed above the insulator 47.

[0117] An insulator 49 and an insulator 61 are stacked in this order on the insulator 47. Furthermore, a transistor 92 is provided above the insulator 49. An insulator 81 is provided above the transistor 92. A BEOL (Back End of Line) region for forming wiring of the semiconductor device is provided above the transistor 92. For example, a conductor 59 (conductors 59a to 59d) is provided that connects the transistor 92 to a capacitor. Furthermore, a terminal 58 can be connected to the conductor 59. Note that an insulator 83 is provided above the insulator 81. A conductor 58 that functions as wiring is provided above the insulator 83. An insulator 85 is provided above the conductor 58, and a conductor 59 that functions as wiring is provided above the insulator 85. An insulator 87 is provided above the conductor 59, and a conductor 72 (conductors 72a and 72b) that functions as a terminal is provided above the insulator 87. Note that the transistor 92 may be disposed so as to be partially embedded in the insulator 49 and the insulator 61.

[0118] In this embodiment, the conductor 58 and the conductor 59 have a single-layer structure, but the present invention is not limited to this structure and may have a laminated structure of two or more layers. For example, a conductor having a barrier property and a conductor having high adhesion to the conductor having high conductivity may be formed between a conductor having a barrier property and a conductor having high conductivity.

[0119] Conductor 58 and conductor 59 can be made of a conductive material such as a metal material, an alloy material, or a metal oxide material. A high-melting-point material such as tungsten or molybdenum, which has both heat resistance and conductivity, is preferably used, and tungsten is particularly preferred. Furthermore, when forming conductors 58 and 59 in the same process as other components such as conductors, low-resistance metal materials such as Cu (copper) or Al (aluminum) can be used.

[0120] Conductor 56 (conductors 56a to 56d), conductor 71 (conductor 71a, conductor 71b), or a conductor constituting transistor 92 (e.g., conductor 503) is embedded in insulator 47, insulator 49, insulator 61, insulator 81, insulator 83, insulator 85, or insulator 87. Conductor 56 functions as a plug or wiring connecting to capacitor 95 and transistor 92. Conductor 71 also functions as a plug or wiring connecting to metal oxynitride film 20 functioning as a cathode electrode of inorganic light-emitting element 100. Metal oxynitride film 20 functions as a common electrode. Therefore, a display device having multiple pixels preferably includes one or more conductors 71. While FIG. 8 illustrates an example in which conductor 71a and conductor 71b are provided for each pixel, this is not limiting.

[0121] Conductor 56 and conductor 71 can be made of a conductive material such as a metal material, alloy material, metal nitride material, or metal oxide material, either in a single layer or in a laminated form. High-melting-point materials such as tungsten and molybdenum, which have both heat resistance and conductivity, are preferably used, and tungsten is preferred. Alternatively, they are preferably made of a low-resistance conductive material such as aluminum or copper. The use of a low-resistance conductive material can reduce wiring resistance.

[0122] The insulators 63, 65, 67, and 69 will be described in detail with reference to FIG.

[0123] Next, the transistor 92 will be described. The semiconductor layer of the transistor 92 preferably contains oxygen and one or more of In, Ga, Sn, and Zn. Therefore, the semiconductor layer of the transistor 92 can be said to include an oxide semiconductor. A transistor that includes an oxide semiconductor (OS), a type of metal oxide, in a semiconductor layer where a channel of the transistor is formed is called an "OS transistor" or an "OS-FET." It is known that the electrical characteristics of an OS transistor vary little with temperature. Furthermore, because the semiconductor layer of an OS transistor has a large energy gap, it can exhibit extremely low off-state current of several yA / μm (current value per μm of channel width). Therefore, an OS transistor is preferably applied to a memory device. The structure of an OS transistor will be described in detail with reference to FIG. 9.

[0124] Here, we will describe a pixel using an OS transistor. A pixel using an OS transistor can suppress degradation of data stored in the pixel even when power supply is stopped. Therefore, the pixel can reduce the capacity required to store data, making it possible to provide a display device suitable for high-density display. Furthermore, by utilizing the pixel's extremely low off-state current, the number of times a still image is rewritten can be reduced, enabling intermittent drive (IDS drive) that leads to low power consumption.

[0125] IDS drive is an idling stop drive that operates at a slower frame frequency than normal. In IDS drive, image data rewriting is stopped after the image data write process is completed. By writing image data once and then extending the interval until the next image data write, it is possible to reduce the power consumption required for writing image data during that time. The frame frequency of IDS drive can be, for example, between 1 / 100 and 1 / 10 of that of normal operation (typically between 60 Hz and 240 Hz). Still images use the same video signal between consecutive frames. Therefore, IDS drive mode is particularly effective when displaying still images.

[0126] Furthermore, the off-state current of OS transistors hardly increases even in high-temperature environments. Specifically, the off-state current hardly increases even in ambient temperatures above room temperature and below 200°C. Furthermore, the on-state current is less likely to decrease even in high-temperature environments. Furthermore, OS transistors have a high withstand voltage between the source and drain. Even when inorganic light-emitting elements reach high temperatures, the use of OS transistors as transistors constituting display devices and lighting devices allows for stable operation even in high-temperature environments, thereby enabling the realization of highly reliable display devices and lighting devices.

[0127] Furthermore, OS transistors can be formed by sputtering during the back-end of life (BEOL) process for forming wiring in semiconductor devices. Therefore, a single semiconductor device can be formed using transistors with different transistor characteristics. In other words, the use of OS transistors makes it easy to form a system-on-chip (SOC).

[0128] Note that an OS transistor can have a back gate. The back gate is disposed so that a channel formation region of the semiconductor layer is sandwiched between the gate and the back gate. The back gate can function in the same manner as the gate. The threshold voltage of the transistor can be changed by changing the voltage of the back gate. The voltage of the back gate may be the same as that of the gate, or may be GND or any other voltage.

[0129] In addition, since the gate and back gate are generally formed of conductive layers, they have the function of preventing electric fields generated outside the transistor from acting on the semiconductor layer where the channel is formed (particularly, electrostatic shielding function against static electricity), which means that fluctuations in the electrical characteristics of the transistor due to the influence of external electric fields such as static electricity can be prevented.

[0130] Next, a description will be given of the insulators 41, 43, 47, 49, 61, 85, and 87. It is preferable that any of the insulators described above be made of a material that has barrier properties against oxygen and hydrogen.

[0131] In particular, the insulators 49 and 61 are preferably formed using films having barrier properties that prevent hydrogen and impurities from diffusing from a region where the inorganic light-emitting element 100 is provided to a region where the transistor 92 is provided. The insulator 83 is preferably formed using a film having barrier properties that prevent hydrogen and impurities from diffusing from the outside to a region where the transistor 92 is provided.

[0132] An example of a film having a barrier property against hydrogen is silicon nitride formed by a CVD method. Here, hydrogen diffusion into a semiconductor element having an oxide semiconductor, such as the transistor 92, may degrade the characteristics of the semiconductor element. Therefore, it is preferable to use a film that suppresses hydrogen diffusion between the transistor 92 and the inorganic light-emitting element. Specifically, the film that suppresses hydrogen diffusion is a film that releases a small amount of hydrogen.

[0133] The amount of desorbed hydrogen can be analyzed using, for example, thermal desorption spectroscopy (TDS). For example, the amount of desorbed hydrogen from the insulator 49 is calculated by TDS analysis as follows: when the surface temperature of the film is in the range of 50° C. to 500° C., the amount of desorbed hydrogen converted into hydrogen atoms is 10×10 per area of ​​the insulator 49. 15 atoms / cm 2 Less than or equal to 5 x 10 15 atoms / cm 2The following is fine.

[0134] An example of a film having barrier properties against hydrogen is silicon nitride formed by a CVD method. Here, hydrogen diffusion into a semiconductor element having an oxide semiconductor, such as the transistor 92, may degrade the characteristics of the semiconductor element. Therefore, it is preferable to use a film that suppresses hydrogen diffusion between the transistor 92 and the inorganic light-emitting element 100. Specifically, the film that suppresses hydrogen diffusion is a film that releases a small amount of hydrogen.

[0135] In particular, silicon nitride has a high blocking effect of preventing the permeation of both oxygen and impurities such as hydrogen and moisture, which can cause fluctuations in the electrical characteristics of a transistor. Therefore, silicon nitride can prevent impurities such as hydrogen and moisture from entering the transistor 92 during and after the transistor manufacturing process. Silicon nitride can also suppress the release of oxygen from the oxide that constitutes the transistor 92. Therefore, silicon nitride is suitable for use as a protective film for the transistor 92.

[0136] Furthermore, for example, it is preferable that the insulator 61 has a lower dielectric constant than the insulator 49. For example, the relative dielectric constant of the insulator 61 is preferably less than 4, more preferably less than 3. For example, the relative dielectric constant of the insulator 61 is preferably 0.7 times or less, more preferably 0.6 times or less, the relative dielectric constant of the insulator 49. By using a material with a low dielectric constant as the interlayer film, it is possible to reduce the parasitic capacitance that occurs between wirings. For example, a silicon oxide film or a silicon oxynitride film can be used as the insulator 61.

[0137] Furthermore, the conductors 56 and 71 in the regions in contact with the insulator 49 are preferably conductors that have barrier properties against oxygen, hydrogen, and water. With this configuration, the inorganic light-emitting element 100 can be separated from the transistor 92 by a layer that has barrier properties against oxygen, hydrogen, and water, and diffusion of hydrogen from the inorganic light-emitting element 100 to the transistor 92 can be suppressed.

[0138] Next, the substrate will be described. Since substrate 10 is located on the side where light from the light-emitting diode is extracted, it is preferable to use a material that is highly transparent to visible light. Examples of materials that can be used for substrate 10 and substrate 11 include sapphire, yttria-stabilized zirconia, glass, quartz, and resin. Note that films such as resin films may also be used for substrate 10 and substrate 11. This allows for a lighter and thinner display device.

[0139] It is preferable to use phosphors or quantum dots (QDs) for the color conversion layer. Quantum dots, in particular, have a narrow peak width in the emission spectrum, allowing for emission of light with good color purity. This can improve the display quality of the display device.

[0140] The color conversion layer can be formed using a droplet ejection method (for example, an inkjet method), a coating method, an imprint method, various printing methods (screen printing, offset printing), etc. A color conversion film such as a quantum dot film may also be used.

[0141] When processing a film to be used as a color conversion layer, it is preferable to use a photolithography method. Photolithography methods include 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, and a method in which a photosensitive thin film is formed, and then the thin film is processed into a desired shape by exposure and development. For example, an island-shaped color conversion layer can be formed by forming a thin film using a material in which quantum dots are mixed into a photoresist, and processing the thin film using a photolithography method.

[0142] The material constituting the quantum dots is not particularly limited, and examples thereof include Group 14 elements, Group 15 elements, Group 16 elements, compounds consisting of multiple Group 14 elements, compounds of an element belonging to Groups 4 to 14 and a Group 16 element, compounds of a Group 2 element and a Group 16 element, compounds of a Group 13 element and a Group 15 element, compounds of a Group 13 element and a Group 17 element, compounds of a Group 14 element and a Group 15 element, compounds of a Group 11 element and a Group 17 element, iron oxides, titanium oxides, chalcogenide spinels, and various semiconductor clusters.

[0143] Specifically, cadmium selenide, cadmium sulfide, cadmium telluride, zinc selenide, zinc oxide, zinc sulfide, zinc telluride, mercury sulfide, mercury selenide, mercury telluride, indium arsenide, indium phosphide, gallium arsenide, gallium phosphide, indium nitride, gallium nitride, indium antimonide, gallium antimonide, aluminum phosphide, aluminum arsenide, aluminum antimonide, lead selenide, lead telluride, lead sulfide, indium selenide, terephthalic acid, Indium sulfide, indium sulfide, gallium selenide, arsenic sulfide, arsenic selenide, arsenic telluride, antimony sulfide, antimony selenide, antimony telluride, bismuth sulfide, bismuth selenide, bismuth telluride, silicon, silicon carbide, germanium, tin, selenium, tellurium, boron, carbon, phosphorus, boron nitride, boron phosphide, boron arsenide, aluminum nitride, aluminum sulfide, barium sulfide, barium selenide, barium telluride, calcium sulfide, selenide Calcium, calcium telluride, beryllium sulfide, beryllium selenide, beryllium telluride, magnesium sulfide, magnesium selenide, germanium sulfide, germanium selenide, germanium telluride, tin sulfide, tin selenide, tin telluride, lead oxide, copper fluoride, copper chloride, copper bromide, copper iodide, copper oxide, copper selenide, nickel oxide, cobalt oxide, cobalt sulfide, iron oxide, iron sulfide, manganese oxide, molybdenum sulfide, vanadium oxide, tungsten oxide, tungsten oxide Examples of the quantum dots include tungsten, titanium oxide, zirconium oxide, silicon nitride, germanium nitride, aluminum oxide, barium titanate, a compound of selenium, zinc, and cadmium, a compound of indium, arsenic, and phosphorus, a compound of cadmium, selenium, and sulfur, a compound of cadmium, selenium, and tellurium, a compound of indium, gallium, and arsenic, a compound of indium, gallium, and selenium, a compound of indium, selenium, and sulfur, a compound of copper, indium, and sulfur, and combinations thereof. Also, so-called alloy-type quantum dots, whose composition is expressed in any ratio, may be used.

[0144] Quantum dot structures include core, core-shell, and core-multishell types. Quantum dots have a high proportion of surface atoms, making them highly reactive and prone to aggregation. Therefore, it is preferable that a protective agent or protective group is attached to the surface of the quantum dots. By attaching the protective agent or providing the protective group, aggregation can be prevented and solubility in a solvent can be increased. It is also possible to reduce reactivity and improve electrical stability.

[0145] Since the band gap of quantum dots increases as their size decreases, their size can be adjusted appropriately to obtain light of the desired wavelength. As the crystal size decreases, the emission of quantum dots shifts toward the blue side, i.e., toward higher energy, so by changing the size of the quantum dots, the emission wavelength can be adjusted across the wavelength ranges of the ultraviolet, visible, and infrared spectrum. The size (diameter) of quantum dots is, for example, 0.5 nm or more and 20 nm or less, preferably 1 nm or more and 10 nm or less. The narrower the size distribution of quantum dots, the narrower the emission spectrum, resulting in emission with excellent color purity. The shape of quantum dots is not particularly limited and may be spherical, rod-shaped, disc-shaped, or other shapes. Quantum rods, which are rod-shaped quantum dots, have the function of emitting directional light.

[0146] The colored layer is a colored layer that transmits light in a specific wavelength range. For example, a color filter that transmits light in the red, green, blue, or yellow wavelength range can be used. Materials that can be used for the colored layer include metal materials, resin materials, and resin materials containing pigments or dyes.

[0147] As shown in Figures 9A and 9B, transistor 92 has conductor 503 arranged so as to be embedded in insulator 49 and insulator 61, insulator 63 arranged on insulator 61 and conductor 503, insulator 65 arranged on insulator 63, insulator 67 arranged on insulator 65, oxide 530a arranged on insulator 67, oxide 530b arranged on oxide 530a, conductors 542a and 542b arranged spaced apart from each other on oxide 530b, insulator 81 arranged on conductors 542a and 542b and having an opening formed therein overlapping with conductors 542a and 542b, insulator 545 arranged on the bottom and side surfaces of the opening, and conductor 560 arranged on the surface on which insulator 545 is formed.

[0148] 9A and 9B, it is preferable that insulator 69 be disposed between oxide 530a, oxide 530b, conductor 542a, and conductor 542b and insulator 81. It is preferable that conductor 560 include conductor 560a disposed inside insulator 545 and conductor 560b disposed so as to be embedded inside conductor 560a. It is preferable that insulator 83 be disposed on insulator 81, conductor 560, and insulator 545, as shown in FIGS.

[0149] In this specification and other documents, the oxide 530a and the oxide 530b may be collectively referred to as the oxide 530.

[0150] Note that although the transistor 92 has a two-layer structure of the oxide 530a and the oxide 530b in and around the channel formation region, the present invention is not limited to this structure. For example, the oxide 530b may be a single layer or a stack of three or more layers.

[0151] Although the conductor 560 of the transistor 92 has a two-layer structure, the present invention is not limited to this. For example, the conductor 560 may have a single-layer structure or a three- or more-layer structure. The transistor 92 shown in FIGS. 8 and 12 is merely an example and is not limited to this structure. An appropriate transistor may be used depending on the circuit configuration, driving method, and the like.

[0152] Here, the conductor 560 functions as the gate electrode of the transistor, and the conductors 542a and 542b function as the source and drain electrodes, respectively. As described above, the conductor 560 is formed so as to be embedded in the opening of the insulator 81 and in the region sandwiched between the conductors 542a and 542b. The arrangement of the conductors 560, 542a, and 542b is selected in a self-aligned manner with respect to the opening of the insulator 81. That is, in the transistor 92, the gate electrode can be positioned between the source and drain electrodes in a self-aligned manner. Therefore, the conductor 560 can be formed without providing an alignment margin, thereby reducing the area occupied by the transistor 92. This allows for miniaturization and high integration of semiconductor devices.

[0153] Furthermore, since the conductor 560 is formed in a self-aligned manner in the region between the conductor 542a and the conductor 542b, the conductor 560 does not have a region that overlaps with the conductor 542a or the conductor 542b. This reduces the parasitic capacitance formed between the conductor 560 and the conductor 542a and the conductor 542b. This improves the switching speed of the transistor 92 and provides high frequency characteristics.

[0154] The conductor 560 may function as a first gate (also referred to as a top gate) electrode. The conductor 503 may function as a second gate (also referred to as a bottom gate) electrode. In this case, the threshold voltage of the transistor 92 can be controlled by changing the voltage applied to the conductor 503 independently of the voltage applied to the conductor 560. In particular, applying a negative voltage to the conductor 503 can increase the threshold voltage of the transistor 92 above 0 V, thereby reducing the off-state current. Therefore, applying a negative voltage to the conductor 503 can reduce the drain current when the voltage applied to the conductor 560 is 0 V, compared to when no negative voltage is applied.

[0155] The conductor 503 is arranged to overlap the oxide 530 and the conductor 560. In this way, when a voltage is applied to the conductor 560 and the conductor 503, the electric field generated from the conductor 560 and the electric field generated from the conductor 503 are connected, and a channel formation region formed in the oxide 530 can be covered.

[0156] In this specification, a transistor configuration in which a channel formation region is electrically surrounded by the electric field of a pair of gate electrodes (a first gate electrode and a second gate electrode) is referred to as a surrounded channel (S-channel) structure. In this specification, the surrounded channel (S-channel) structure is characterized in that the side and periphery of the oxide 530 in contact with the conductors 542a and 542b, which function as source and drain electrodes, are I-type, just like the channel formation region. Furthermore, the side and periphery of the oxide 530 in contact with the conductors 542a and 542b are in contact with the insulator 69, so they can be I-type, just like the channel formation region. In this specification, the I-type can be treated as the same as the high-purity intrinsic oxide, which will be described later. The S-channel structure disclosed in this specification differs from the fin type and planar type structures. The S-channel structure enhances resistance to the short-channel effect, or in other words, can provide a transistor that is less susceptible to the short-channel effect.

[0157] The conductor 503 has a similar structure to the conductor 56, with the conductor 503a being formed in contact with the inner walls of the openings of the insulators 49 and 61, and the conductor 503b being formed further inward. Note that, although the transistor 92 shows a structure in which the conductors 503a and 503b are stacked, the present invention is not limited to this. For example, the conductor 503 may have a single layer structure or a stacked structure of three or more layers. Note that FIG. 8 shows an example in which the conductor 56 is a single layer, and FIG. 9 shows an example in which the conductor 503 has two layers.

[0158] Here, the conductor 503a is preferably made of a conductive material that has the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms (the impurities are less likely to permeate). Alternatively, it is preferably made of a conductive material that has the function of suppressing the diffusion of oxygen (for example, at least one of oxygen atoms, oxygen molecules, etc.) (the oxygen is less likely to permeate). In this specification, the function of suppressing the diffusion of impurities or oxygen refers to the function of suppressing the diffusion of any one or all of the impurities and oxygen.

[0159] For example, the conductor 503a has a function of suppressing the diffusion of oxygen, so that the conductor 503b can be prevented from being oxidized and its conductivity from decreasing.

[0160] Furthermore, when the conductor 503 also functions as a wiring, it is preferable that the conductor 503b be made of a highly conductive material containing tungsten, copper, or aluminum as a main component. Note that, although the conductor 503 is illustrated in this embodiment as a stack of the conductors 503a and 503b, the conductor 503 may have a single-layer structure.

[0161] The insulators 63, 65, and 67 function as a second gate insulating film.

[0162] Here, the insulator 67 in contact with the oxide 530 preferably contains more oxygen than the oxygen required for the stoichiometric composition. The oxygen is easily released from the film by heating. In this specification and elsewhere, oxygen released by heating may be referred to as "excess oxygen." That is, the insulator 67 preferably has a region containing excess oxygen (also referred to as an "excess oxygen region"). By providing such an insulator containing excess oxygen in contact with the oxide 530, oxygen vacancies (Vo) in the oxide 530 can be reduced, improving the reliability of the transistor 92. When hydrogen enters the oxygen vacancies in the oxide 530, the vacancies (hereinafter sometimes referred to as VoH) can function as donors and generate electrons as carriers. Furthermore, some of the hydrogen may bond with oxygen that is bonded to metal atoms to generate electrons as carriers. Therefore, a transistor using an oxide semiconductor containing a large amount of hydrogen is likely to have normally-on characteristics. Furthermore, hydrogen in an oxide semiconductor is easily mobile due to stress such as heat or an electric field. Therefore, if the oxide semiconductor contains a large amount of hydrogen, the reliability of the transistor may be reduced. In one embodiment of the present invention, it is preferable to reduce the VOH in the oxide 530 as much as possible to make it highly purified intrinsic or substantially highly purified intrinsic. To obtain an oxide semiconductor with a sufficiently reduced VOH, it is important to remove impurities such as moisture and hydrogen from the oxide semiconductor (also referred to as "dehydration" or "dehydrogenation treatment") and to supply oxygen to the oxide semiconductor to fill oxygen vacancies (also referred to as "oxygenation treatment"). Stable electrical characteristics can be achieved by using an oxide semiconductor with a sufficiently reduced amount of impurities such as VOH for the channel formation region of a transistor.

[0163] Specifically, it is preferable to use an oxide material from which a portion of oxygen is released by heating as an insulator having an excess oxygen region. The oxide material from which oxygen is released by heating is an oxide material from which the amount of released oxygen converted to oxygen atoms is 1.0 × 10 in TDS (Thermal Desorption Spectroscopy) analysis. 18 atoms / cm 3or more, preferably 1.0 × 10 19 atoms / cm 3 More preferably, 2.0 × 10 19 atoms / cm 3 or more, or 3.0 x 10 20 atoms / cm 3 The oxide film is one having the above properties. The surface temperature of the film during the TDS analysis is preferably in the range of 100°C or higher and 700°C or lower, or 100°C or higher and 400°C or lower.

[0164] Alternatively, the oxide 530 may be brought into contact with an insulator having the excess oxygen region and subjected to one or more of heat treatment, microwave treatment, and RF treatment. This treatment can remove water or hydrogen from the oxide 530. For example, a reaction occurs in the oxide 530 that breaks the VoH bond, in other words, the reaction "VoH → Vo + H" occurs, resulting in dehydrogenation. Some of the generated hydrogen may combine with oxygen to form HO and be removed from the oxide 530 or an insulator near the oxide 530. Some of the hydrogen may also be gettered by the conductor 542.

[0165] The microwave treatment is preferably performed using, for example, an apparatus having a power source for generating high-density plasma or an apparatus having a power source for applying RF to the substrate side. For example, high-density oxygen radicals can be generated by using an oxygen-containing gas and high-density plasma, and the oxygen radicals generated by the high-density plasma can be efficiently introduced into the oxide 530 or an insulator near the oxide 530 by applying RF to the substrate side. The microwave treatment is performed at a pressure of 133 Pa or higher, preferably 200 Pa or higher, and more preferably 400 Pa or higher. The gases introduced into the microwave treatment apparatus may be, for example, oxygen and argon, with an oxygen flow ratio (O2 / (O2+Ar)) of 50% or less, preferably 10% to 30%.

[0166] During the manufacturing process of the transistor 92, heat treatment is preferably performed while the surface of the oxide 530 is exposed. The heat treatment may be performed, for example, at a temperature of 100° C. to 450° C., more preferably 350° C. to 400° C. Note that the heat treatment is performed in a nitrogen gas or inert gas atmosphere, or in an atmosphere containing an oxidizing gas at 10 ppm or more, 1% or more, or 10% or more. For example, the heat treatment is preferably performed in an oxygen atmosphere. This allows oxygen to be supplied to the oxide 530, thereby reducing oxygen vacancies (Vo). The heat treatment may be performed under reduced pressure. Alternatively, the heat treatment may be performed in a nitrogen gas or inert gas atmosphere, followed by an atmosphere containing an oxidizing gas at 10 ppm or more, 1% or more, or 10% or more to replenish desorbed oxygen. Alternatively, the heat treatment may be performed in an atmosphere containing an oxidizing gas at 10 ppm or more, 1% or more, or 10% or more, followed by another heat treatment in a nitrogen gas or inert gas atmosphere.

[0167] By subjecting the oxide 530 to oxygen addition treatment, the oxygen vacancies in the oxide 530 can be repaired by the supplied oxygen, in other words, the reaction "Vo + O → null" can be promoted. Furthermore, the supplied oxygen reacts with the hydrogen remaining in the oxide 530, and the hydrogen can be removed as H2O (dehydration). As a result, the hydrogen remaining in the oxide 530 recombines with the oxygen vacancies to form V O The formation of H can be suppressed.

[0168] Furthermore, when the insulator 67 has an excess oxygen region, the insulator 65 preferably has a function of suppressing the diffusion of oxygen (for example, oxygen atoms, oxygen molecules, etc.) (is less permeable to the oxygen).

[0169] The insulator 65 preferably has a function of suppressing the diffusion of oxygen and impurities, which prevents the oxygen contained in the oxide 530 from diffusing toward the insulator 63. Furthermore, the conductor 503 can be prevented from reacting with the insulator 67 and the oxygen contained in the oxide 530.

[0170] The insulator 65 is preferably a single-layer or multi-layer insulator containing a high-k material, such as aluminum oxide, hafnium oxide, oxides containing aluminum and hafnium (hafnium aluminate), tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO), or (Ba,Sr)TiO (BST). As transistors become smaller and more highly integrated, thinner gate insulating films can cause problems such as leakage current. Using a high-k material for the insulator that functions as the gate insulating film allows for a reduction in gate voltage during transistor operation while maintaining the physical film thickness.

[0171] In particular, it is preferable to use an insulator containing an oxide of one or both of aluminum and hafnium, which is an insulating material that has the function of suppressing the diffusion of impurities and oxygen (i.e., the oxygen is less likely to permeate). Aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate) is preferably used as the insulator containing an oxide of one or both of aluminum and hafnium. When the insulator 65 is formed using such a material, the insulator 65 functions as a layer that suppresses the release of oxygen from the oxide 530 and the intrusion of impurities such as hydrogen into the oxide 530 from the periphery of the transistor 92.

[0172] Alternatively, for example, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide may be added to these insulators. Alternatively, these insulators may be nitrided. Silicon oxide, silicon oxynitride, or silicon nitride may be stacked on the above insulators.

[0173] Furthermore, it is preferable that the insulator 63 is thermally stable. For example, silicon oxide and silicon oxynitride are suitable because they are thermally stable. Furthermore, by combining a high-k insulator with silicon oxide or silicon oxynitride, it is possible to obtain the insulator 63 having a thermally stable layered structure with a high dielectric constant.

[0174] 9A and 9B, the second gate insulating film has a three-layer structure including insulators 63, 65, and 67. However, the second gate insulating film may have a single-layer structure, a two-layer structure, or a four- or more-layer structure. In this case, the second gate insulating film is not limited to a stack structure made of the same material, and may have a stack structure made of different materials.

[0175] The transistor 92 uses a metal oxide functioning as an oxide semiconductor for the oxide 530 including the channel formation region. Note that the oxide semiconductor preferably contains at least one of In and Zn. For example, the oxide 530 may be a metal oxide such as In-M-Zn oxide (wherein M is one or more elements selected from aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, etc.).

[0176] The metal oxide functioning as an oxide semiconductor may be formed by a sputtering method or an ALD (Atomic Layer Deposition) method. Note that the metal oxide functioning as an oxide semiconductor will be described in detail in other embodiments.

[0177] The metal oxide that functions as a channel formation region in the oxide 530 preferably has a band gap of 2 eV or more, preferably 2.5 eV or more. By using a metal oxide with a wide band gap, the off-state current of the transistor can be reduced.

[0178] The oxide 530 has the oxide 530a below the oxide 530b, and thus can suppress the diffusion of impurities from components formed below the oxide 530a to the oxide 530b.

[0179] Note that oxide 530 preferably has a stacked structure of multiple oxide layers with different atomic ratios of each metal atom. Specifically, the atomic ratio of element M among the constituent elements in the metal oxide used for oxide 530a is preferably greater than the atomic ratio of element M among the constituent elements in the metal oxide used for oxide 530b. Furthermore, the atomic ratio of element M to In in the metal oxide used for oxide 530a is preferably greater than the atomic ratio of element M to In in the metal oxide used for oxide 530b. Furthermore, the atomic ratio of In to element M in the metal oxide used for oxide 530b is preferably greater than the atomic ratio of In to element M in the metal oxide used for oxide 530a.

[0180] The energy of the conduction band minimum of the oxide 530a is preferably higher than that of the oxide 530b, or in other words, the electron affinity of the oxide 530a is preferably smaller than that of the oxide 530b.

[0181] Here, the energy level of the conduction band minimum changes gradually at the junction between the oxide 530a and the oxide 530b. In other words, the energy level of the conduction band minimum at the junction between the oxide 530a and the oxide 530b changes continuously or forms a continuous junction. To achieve this, it is preferable to reduce the defect level density of the mixed layer formed at the interface between the oxide 530a and the oxide 530b.

[0182] Specifically, when the oxide 530a and the oxide 530b have a common element (main component) other than oxygen, a mixed layer with a low density of defect states can be formed. For example, when the oxide 530b is an In-Ga-Zn oxide, the oxide 530a may be an In-Ga-Zn oxide, a Ga-Zn oxide, a gallium oxide, or the like.

[0183] In this case, the main carrier path is the oxide 530b. By configuring the oxide 530a as described above, the defect state density at the interface between the oxide 530a and the oxide 530b can be reduced. As a result, the influence of interface scattering on carrier conduction is reduced, and the transistor 92 can obtain a high on-state current.

[0184] Conductors 542a and 542b, which function as a source electrode and a drain electrode, are provided on oxide 530b. Conductors 542a and 542b are preferably made of a metal element selected from aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, ruthenium, iridium, strontium, and lanthanum, or an alloy containing any of the above metal elements or an alloy combining any of the above metal elements. For example, tantalum nitride, titanium nitride, tungsten, a nitride containing titanium and aluminum, a nitride containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, an oxide containing strontium and ruthenium, or an oxide containing lanthanum and nickel is preferably used. In addition, tantalum nitride, titanium nitride, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, and oxides containing lanthanum and nickel are preferred because they are conductive materials that are resistant to oxidation or materials that maintain conductivity even when absorbing oxygen.Furthermore, metal nitride films such as tantalum nitride are preferred because they have barrier properties against hydrogen or oxygen.

[0185] 9A and 9B, the conductor 542a and the conductor 542b are shown as single-layer structures, but they may be stacked with two or more layers. For example, a tantalum nitride film and a tungsten film may be stacked. Alternatively, a titanium film and an aluminum film may be stacked. Alternatively, a two-layer structure in which an aluminum film is stacked on a tungsten film, a two-layer structure in which a copper film is stacked on a copper-magnesium-aluminum alloy film, a two-layer structure in which a copper film is stacked on a titanium film, or a two-layer structure in which a copper film is stacked on a tungsten film may be used.

[0186] Other examples include a three-layer structure in which a titanium film or titanium nitride film is laminated on the titanium film or titanium nitride film, an aluminum film or copper film is laminated on the titanium film or titanium nitride film, and a titanium film or titanium nitride film is further formed thereon, and a three-layer structure in which a molybdenum film or molybdenum nitride film is laminated on the molybdenum film or molybdenum nitride film, an aluminum film or copper film is laminated on the molybdenum film or molybdenum nitride film, and a molybdenum film or molybdenum nitride film is further formed thereon. Note that a transparent conductive material containing indium oxide, tin oxide, or zinc oxide may also be used.

[0187] 9A, regions 543a and 543b may be formed as low-resistance regions at and near the interface of the oxide 530 with the conductor 542a (conductor 542b). In this case, the region 543a functions as one of the source region and the drain region, and the region 543b functions as the other of the source region and the drain region. A channel formation region is formed in the region sandwiched between the regions 543a and 543b.

[0188] By providing the conductor 542a (conductor 542b) so as to be in contact with the oxide 530, the oxygen concentration in the region 543a (region 543b) may be reduced. Also, a metal compound layer containing the metal contained in the conductor 542a (conductor 542b) and components of the oxide 530 may be formed in the region 543a (region 543b). In such a case, the carrier density in the region 543a (region 543b) increases, and the region 543a (region 543b) becomes a low-resistance region.

[0189] Insulator 69 is provided to cover conductor 542 a and conductor 542 b and suppresses oxidation of conductor 542 a and conductor 542 b. In this case, insulator 69 may be provided to cover the side surface of oxide 530 and to be in contact with insulator 67.

[0190] The insulator 69 can be a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, neodymium, lanthanum, magnesium, etc. Alternatively, the insulator 69 can be silicon nitride oxide, silicon nitride, or the like.

[0191] In particular, it is preferable to use, as the insulator 69, an insulator containing an oxide of either or both of aluminum and hafnium, such as aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate). Hafnium aluminate is particularly preferable because it has higher heat resistance than hafnium oxide film. Therefore, it is less likely to crystallize during heat treatment in a later process. Note that if the conductors 542a and 542b are made of oxidation-resistant materials or if their conductivity does not decrease significantly even when they absorb oxygen, the insulator 69 is not an essential component. It can be designed appropriately depending on the desired transistor characteristics.

[0192] The insulator 69 can prevent impurities such as water and hydrogen contained in the insulator 81 from diffusing into the oxide 530b through the insulator 545. The insulator 69 can also prevent the conductor 560 from being oxidized by excess oxygen contained in the insulator 81.

[0193] The insulator 545 functions as a first gate insulating film. Like the insulator 67, the insulator 545 is preferably formed using an insulator that contains excess oxygen and releases oxygen by heating.

[0194] Specifically, silicon oxide having excess oxygen, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine is added, silicon oxide to which carbon is added, silicon oxide to which carbon and nitrogen are added, and silicon oxide having vacancies can be used. In particular, silicon oxide and silicon oxynitride are preferable because they are stable against heat.

[0195] By providing an insulator containing excess oxygen as the insulator 545, oxygen can be effectively supplied from the insulator 545 to the channel formation region of the oxide 530b. As with the insulator 67, the concentration of impurities such as water or hydrogen in the insulator 545 is preferably reduced. The thickness of the insulator 545 is preferably 1 nm to 20 nm.

[0196] Furthermore, a metal oxide may be provided between the insulator 545 and the conductor 560 to efficiently supply excess oxygen contained in the insulator 545 to the oxide 530. The metal oxide preferably suppresses oxygen diffusion from the insulator 545 to the conductor 560. By providing a metal oxide that suppresses oxygen diffusion, the diffusion of excess oxygen from the insulator 545 to the conductor 560 is suppressed. That is, a decrease in the amount of excess oxygen supplied to the oxide 530 can be suppressed. Furthermore, oxidation of the conductor 560 due to excess oxygen can be suppressed. As the metal oxide, any material that can be used for the insulator 69 may be used.

[0197] The insulator 545 may have a layered structure, similar to the second gate insulating film. As transistors become smaller and more highly integrated, thinner gate insulating films can cause problems such as leakage current. Therefore, by using a layered structure of a high-k material and a thermally stable material for the insulator that functions as the gate insulating film, it becomes possible to reduce the gate voltage during transistor operation while maintaining the physical film thickness. Furthermore, a layered structure that is thermally stable and has a high dielectric constant can be achieved.

[0198] The conductor 560 functioning as the first gate electrode is shown as having a two-layer structure in FIGS. 9A and 9B, but may have a single-layer structure or a stacked structure of three or more layers.

[0199] The conductor 560a is preferably made of a conductive material that suppresses the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (e.g., NO, NO, and the like), and copper atoms. Alternatively, a conductive material that suppresses the diffusion of oxygen (e.g., at least one of oxygen atoms, oxygen molecules, and the like) is preferably used. The oxygen-suppressing function of the conductor 560a can suppress the oxidation of the conductor 560b due to oxygen contained in the insulator 545, which can reduce the conductivity. Examples of conductive materials that suppress the diffusion of oxygen include tantalum, tantalum nitride, ruthenium, and ruthenium oxide. Alternatively, the conductor 560a can be made of an oxide semiconductor that can be used for the oxide 530. In this case, the conductor 560b can be formed by sputtering to reduce the electrical resistance of the conductor 560a, thereby making it a conductor. This can be called an OC (Oxide Conductor) electrode.

[0200] The conductor 560b is preferably made of a conductive material containing tungsten, copper, or aluminum as a main component. Because the conductor 560b also functions as wiring, it is preferable to use a conductor with high conductivity. For example, a conductive material containing tungsten, copper, or aluminum as a main component can be used. The conductor 560b may have a layered structure, such as a layered structure of titanium or titanium nitride and the above-mentioned conductive material.

[0201] Insulator 81 is provided on conductor 542a and conductor 542b with insulator 69 interposed therebetween. Insulator 81 preferably has an excess oxygen region. For example, insulator 81 preferably includes silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide doped with fluorine, silicon oxide doped with carbon, silicon oxide doped with carbon and nitrogen, silicon oxide having voids, or resin. Silicon oxide and silicon oxynitride are particularly preferred because they are thermally stable. Silicon oxide and silicon oxide having voids are particularly preferred because they allow for easy formation of excess oxygen regions in a later process.

[0202] It is preferable that the insulator 81 has an excess oxygen region. By providing the insulator 81 from which oxygen is released by heating, oxygen in the insulator 81 can be efficiently supplied to the oxide 530. It is preferable that the concentration of impurities such as water or hydrogen in the insulator 81 is reduced.

[0203] The opening of the insulator 81 is formed to overlap the region between the conductors 542a and 542b, so that the conductor 560 is formed so as to be embedded in the opening of the insulator 81 and the region sandwiched between the conductors 542a and 542b.

[0204] When miniaturizing semiconductor devices, it is necessary to shorten the gate length, but it is also necessary to ensure that the conductivity of the conductor 560 does not decrease. If the film thickness of the conductor 560 is increased for this purpose, the conductor 560 may have a shape with a high aspect ratio. In this embodiment, the conductor 560 is provided so as to be embedded in the opening of the insulator 81, and therefore, even if the conductor 560 has a shape with a high aspect ratio, the conductor 560 can be formed without collapsing during the process.

[0205] The insulator 83 is preferably provided in contact with the top surface of the insulator 81, the top surface of the conductor 560, and the top surface of the insulator 545. By forming the insulator 83 by a sputtering method, an excess oxygen region can be provided in the insulator 545 and the insulator 81. This allows oxygen to be supplied from the excess oxygen region into the oxide 530.

[0206] For example, the insulator 83 may be a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, magnesium, and the like.

[0207] In particular, aluminum oxide has high barrier properties and can suppress the diffusion of hydrogen and nitrogen even when it is a thin film with a thickness of 0.5 nm to 3.0 nm. Therefore, aluminum oxide formed by sputtering can function as both an oxygen source and a barrier film against impurities such as hydrogen.

[0208] It is also preferable to provide an insulator 85 functioning as an interlayer film over the insulator 83. Like the insulator 67, the insulator 85 preferably has a reduced concentration of impurities such as water or hydrogen.

[0209] Furthermore, the conductor 540a and the conductor 540b are arranged in openings formed in the insulators 85, 83, 81, and 69. The conductor 540a and the conductor 540b are arranged opposite each other with the conductor 560 interposed therebetween.

[0210] An insulator 87 is provided on the insulator 85. The insulator 87 is preferably made of a substance that has a barrier property against oxygen and hydrogen. Therefore, the insulator 87 can be made of the same material as the insulator 49.

[0211] In particular, silicon nitride has a high blocking effect of preventing the permeation of both oxygen and impurities such as hydrogen and moisture, which can cause fluctuations in the electrical characteristics of a transistor. Therefore, silicon nitride can prevent impurities such as hydrogen and moisture from entering the transistor 92 during and after the transistor manufacturing process. Silicon nitride can also suppress the release of oxygen from the oxide that constitutes the transistor 92. Therefore, silicon nitride is suitable for use as a protective film for the transistor 92.

[0212] After the transistor 92 is formed, an opening may be formed to surround the transistor 92, and an insulator with high barrier properties against hydrogen or water may be formed to cover the opening. By surrounding the transistor 92 with the insulator with high barrier properties, it is possible to prevent moisture and hydrogen from entering from the outside. Alternatively, multiple transistors 92 may be collectively surrounded by an insulator with high barrier properties against hydrogen or water. When forming an opening to surround the transistor 92, for example, it is preferable to form an opening that reaches the insulator 65 or the insulator 49 and form the insulator with high barrier properties in contact with the insulator 65 or the insulator 49, because this can serve as part of the manufacturing process of the transistor 92. Therefore, although not shown in FIG. 8 , it is preferable to form the insulator with high barrier properties so as to surround the sidewall of the conductor 56 or the conductor 71. For example, the insulator with high barrier properties against hydrogen or water may be made of a material similar to the insulator 65 or the insulator 49.

[0213] With this structure, miniaturization or high integration can be achieved in a semiconductor device including a transistor including an oxide semiconductor.

[0214] Examples of substrates that can be used in the semiconductor device of one embodiment of the present invention include glass substrates, quartz substrates, sapphire substrates, ceramic substrates, metal substrates (e.g., stainless steel substrates, substrates having stainless steel foil, tungsten substrates, and substrates having tungsten foil), semiconductor substrates (e.g., single-crystal semiconductor substrates, polycrystalline semiconductor substrates, and compound semiconductor substrates), and silicon-on-insulator (SOI) substrates. Plastic substrates that have heat resistance sufficient to withstand the processing temperatures of this embodiment may also be used. Examples of glass substrates include barium borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, and soda-lime glass. Crystallized glass, for example, can also be used.

[0215] Alternatively, flexible substrates, laminated films, paper containing fibrous materials, or base films can be used as the substrate. Examples of flexible substrates, laminated films, and base films include the following: Plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Synthetic resins such as acrylic are also included. Polypropylene, polyester, polyvinyl fluoride, and polyvinyl chloride are also included. Polyamide, polyimide, aramid resin, epoxy resin, inorganic vapor-deposited film, and paper are also included. In particular, transistors manufactured using semiconductor substrates, single-crystal substrates, or SOI substrates can be manufactured to have small size, high current capacity, and minimal variations in characteristics, size, and shape. Constructing a circuit using such transistors can reduce the power consumption of the circuit or increase the circuit integration.

[0216] Alternatively, a flexible substrate may be used as the substrate, and transistors, resistors, and / or capacitors may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the transistors, resistors, and / or capacitors. The release layer can be used to separate a semiconductor device, after it has been partially or entirely completed, from the substrate and transfer it to another substrate. In this case, the transistors, resistors, and / or capacitors can be transferred to a substrate with poor heat resistance or a flexible substrate. The release layer may be, for example, a laminated structure of an inorganic film such as a tungsten film and a silicon oxide film, a structure in which an organic resin film such as polyimide is formed on a substrate, or a silicon film containing hydrogen.

[0217] That is, a semiconductor device may be formed on a certain substrate and then transferred to another substrate. Examples of substrates onto which a semiconductor device may be transferred include, in addition to the substrates on which the above-mentioned transistors can be formed, paper substrates, cellophane substrates, aramid film substrates, polyimide film substrates, stone substrates, wood substrates, cloth substrates (including natural fibers (silk, cotton, hemp), synthetic fibers (nylon, polyurethane, polyester), or recycled fibers (acetate, cupra, rayon, recycled polyester)), leather substrates, and rubber substrates. By using these substrates, it is possible to manufacture semiconductor devices that are flexible, durable, heat-resistant, lightweight, or thin.

[0218] By providing a semiconductor device over a flexible substrate, an increase in weight can be suppressed and a semiconductor device that is less likely to be damaged can be provided.

[0219] <Transistor variation 1> 10A to 10C is a modified example of the transistor 92 having the configuration shown in Fig. 9A and Fig. 9B. Fig. 10B is a cross-sectional view of the transistor 92A in the channel length direction, and Fig. 10C is a cross-sectional view of the transistor 92A in the channel width direction.

[0220] 10A to 10C differs from the transistor 92 shown in FIGS. 9A and 9B in that the transistor 92A includes an insulator 552, an insulator 48, and an insulator 51. The transistor 92A also differs from the transistor 92 shown in FIGS. 9A and 9B in that the insulator 552 is provided in contact with a side surface of the conductor 540a and the insulator 552 is provided in contact with a side surface of the conductor 540b. The transistor 92A also differs from the transistor 92 shown in FIGS. 9A and 9B in that the insulator 63 is not provided.

[0221] 10A to 10C, the insulator 48 is provided over the insulator 47. Furthermore, the insulator 51 is provided over the insulator 83 and the insulator 48.

[0222] 10A to 10C , insulators 49, 61, 65, 67, 69, 81, and 83 are patterned, and insulator 51 covers them. That is, insulator 51 contacts the top surface of insulator 83, the side surface of insulator 83, the side surface of insulator 81, the side surface of insulator 69, the side surface of insulator 67, the side surface of insulator 65, the side surface of insulator 61, the side surface of insulator 49, and the top surface of insulator 48. As a result, oxide 530 and the like are isolated from the outside by insulators 51 and 48.

[0223] The insulators 48 and 51 preferably have a high function of suppressing diffusion of hydrogen (for example, at least one of hydrogen atoms, hydrogen molecules, and the like) or water molecules. For example, silicon nitride or silicon nitride oxide, which are materials with high hydrogen barrier properties, are preferably used for the insulators 48 and 51. This can suppress diffusion of hydrogen and the like into the oxide 530, thereby suppressing deterioration in the characteristics of the transistor 92A. Therefore, the reliability of the semiconductor device of one embodiment of the present invention can be improved.

[0224] The insulator 552 is provided in contact with the insulator 85, the insulator 51, the insulator 83, the insulator 81, and the insulator 69. The insulator 552 preferably has a function of suppressing diffusion of hydrogen or water molecules. For example, the insulator 552 is preferably made of an insulator with high hydrogen barrier properties, such as silicon nitride, aluminum oxide, or silicon nitride oxide. Silicon nitride is particularly suitable for use as the insulator 552 because it has high hydrogen barrier properties. Using a material with high hydrogen barrier properties for the insulator 552 can suppress diffusion of impurities such as water or hydrogen from the insulator 81 or the like to the oxide 530 through the conductor 540a and the conductor 540b. Furthermore, oxygen contained in the insulator 81 can be suppressed from being absorbed by the conductor 540a and the conductor 540b. As described above, the reliability of the semiconductor device of one embodiment of the present invention can be improved.

[0225] <Transistor variation 2> An example configuration of a transistor 92B will be described using Figures 11A, 11B, and 11C. Figure 11A is a top view of the transistor 92B. Figure 11B is a cross-sectional view of the L1-L2 portion indicated by the dashed-dotted line in Figure 11A. Figure 11C is a cross-sectional view of the W1-W2 portion indicated by the dashed-dotted line in Figure 11A. Note that in the top view of Figure 11A, some elements are omitted for clarity.

[0226] The transistor 92B is a modified example of the transistor 92 and can be substituted for the transistor 92. Therefore, to avoid repetition of the description, the differences between the transistor 92B and the transistor 92 will be mainly described.

[0227] The conductor 560 functioning as the first gate electrode includes a conductor 560a and a conductor 560b on the conductor 560a. The conductor 560a is preferably made of a conductive material that has the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms. Alternatively, the conductor 560a is preferably made of a conductive material that has the function of suppressing the diffusion of oxygen (e.g., at least one of oxygen atoms, oxygen molecules, etc.).

[0228] The conductor 560a has the function of suppressing oxygen diffusion, which improves the material selectivity of the conductor 560b. In other words, the presence of the conductor 560a suppresses oxidation of the conductor 560b, preventing a decrease in conductivity.

[0229] Furthermore, it is preferable to provide an insulator 69 so as to cover the top surface and side surfaces of the conductor 560 and the side surfaces of the insulator 545. Note that the insulator 69 is preferably made of an insulating material that has a function of suppressing the diffusion of impurities such as water or hydrogen, and oxygen. For example, it is preferable to use silicon nitride. Other materials that can be used include metal oxides such as magnesium oxide, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, and tantalum oxide, or silicon nitride oxide.

[0230] Providing the insulator 69 can suppress oxidation of the conductor 560. Furthermore, including the insulator 69 can suppress diffusion of impurities such as water and hydrogen contained in the insulator 81 into the transistor 92B.

[0231] The conductor 560 overlaps part of the conductor 542a and part of the conductor 542b in the transistor 92B, and thus the parasitic capacitance of the transistor 92B is likely to be larger than that of the transistor 92. Therefore, the operating frequency of the transistor 92B tends to be lower than that of the transistor 92. However, the productivity of the transistor 92B is higher than that of the transistor 92 because the process of forming an opening in the insulator 81 or the like and burying the conductor 560, the insulator 545, or the like is not required.

[0232] Figure 12 is a diagram illustrating an example of the configuration of a display device different from that of Figure 8. In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. Furthermore, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0233] 12 differs in that the conductor 54 functioning as the other electrode of the capacitor 95 is further covered with a portion of the side surface of the inorganic light-emitting element 100 via the insulator 41. Therefore, both one and the other of the electrodes of the capacitor 95 function as reflective electrodes. As an example, when the insulator 47a is translucent, the other of the electrodes of the capacitor 95 covering a portion of the side surface of the inorganic light-emitting element 100 functions as a reflective electrode, so that the light L4 emitted from the inorganic light-emitting element 100 can contribute to display via the substrate 11. Furthermore, the other of the electrodes of the capacitor 95 covering a portion of the side surface of the inorganic light-emitting element 100 in the adjacent pixel functions as a reflective electrode, so that the light L5 emitted from the inorganic light-emitting element 100 can contribute to display via the substrate 11.

[0234] When the side where one electrode of the capacitor 95 faces the other electrode of the capacitor 95 is defined as the inside of the one electrode of the capacitor 95, the side where the one electrode of the capacitor 95 does not face the other electrode can be defined as the outside.

[0235] Light L2 emitted from the inorganic light-emitting element 100 is reflected by one of the electrodes of the capacitor 95 and can contribute to display. Light L4 emitted from the inorganic light-emitting element 100 is reflected by the inside of the other electrode of the capacitor 95 and can contribute to display. Light L5 emitted from the inorganic light-emitting element 100 is reflected by the outside of the other electrode of the capacitor 95 of an adjacent pixel and can contribute to display. Thus, the light emitted by the inorganic light-emitting element 100 can be effectively utilized. Furthermore, light L4 and light L5 are reflected by the capacitor 95, which functions as a reflective electrode, and are emitted from the display surface of the display device, which has the effect of widening the viewing angle.

[0236] As another example, the conductor 54 may cover the entire surface of the inorganic light-emitting element 100 except for the display surface from which light is emitted. By covering the entire surface of the inorganic light-emitting element 100 except for the display surface from which light is emitted, the light emitted by the inorganic light-emitting element 100 is emitted from the display surface. This improves the light extraction efficiency of the inorganic light-emitting element 100, and the light reflected by the side surface has the effect of improving the viewing angle. Furthermore, it is possible to reduce fluctuations in the electrical characteristics of the transistor caused by light being irradiated onto the transistor.

[0237] 8, the insulator 47a may be light-transmitting or may be a colored layer. Preferably, a part of the conductor 54 has a region overlapping with the insulator 41 and the metal oxynitride film 20.

[0238] This embodiment mode can be combined with other embodiment modes and examples as appropriate.

[0239] (Embodiment 3) In this embodiment mode, a structural example of a display device using the inorganic light-emitting element described in the above embodiment mode will be described.

[0240] The display device of this embodiment has a function of displaying an image using inorganic light-emitting elements. In this embodiment, in particular, an example in which micro light-emitting diodes (hereinafter also referred to as micro LEDs) are used as the inorganic light-emitting elements will be described.

[0241] By using micro LEDs as display elements, it is possible to reduce the power consumption of display devices. It is also possible to make display devices thinner and lighter. Furthermore, display devices using micro LEDs as display elements can improve display quality because they have high contrast and a wide viewing angle.

[0242] The area of ​​the light-emitting region of the micro LED is 1mm 2 Preferably less than 10,000 μm 2 Less than 3000 μm is more preferable. 2 Less than 700 μm is more preferable 2The following is even more preferred:

[0243] 13A shows a configuration example of a display device 400 using an inorganic light-emitting element. The display device 400 includes a pixel portion 401, a driver circuit 402, and a driver circuit 403.

[0244] The pixel portion 401 is composed of a plurality of pixels pix. Each pixel pix is ​​connected to a wiring SL and a wiring GL. Each wiring GL is connected to a driver circuit 402, and each wiring SL is connected to a driver circuit 403. A selection signal is supplied to the wiring GL, and a video signal is supplied to the wiring SL.

[0245] The driver circuit 402 has a function of supplying a selection signal to the pixel pix. Specifically, the driver circuit 402 has a function of supplying a selection signal to a wiring GL, and the wiring GL has a function of transmitting the selection signal output from the driver circuit 402 to the pixel pix. Note that the driver circuit 402 can also be called a gate driver circuit or a gate driver, and the wiring GL can also be called a selection signal line or a gate line.

[0246] The driver circuit 403 has a function of supplying a video signal to the pixel pix. Specifically, the driver circuit 403 has a function of supplying a video signal to a wiring SL, and the wiring SL has a function of transmitting the video signal output from the driver circuit 403 to the pixel pix. Note that the driver circuit 403 can be called a source-side driver circuit or a source driver, and the wiring SL can also be called a video signal line or a source line.

[0247] 13B shows a configuration example of a pixel pix using an inorganic light-emitting element as a display element. The pixel pix shown in FIG. 13B includes a transistor 91, a transistor 92, a capacitor 95, and an inorganic light-emitting element 100. Note that although the transistors 91 and 92 are n-channel here, the polarity of the transistors can be changed as appropriate. The inorganic light-emitting element described in the above embodiment can be used for the inorganic light-emitting element 100.

[0248] The gate of the transistor 91 is connected to a wiring GL, one of the source or drain is connected to the gate of the transistor 92 and one electrode of the capacitor 95, and the other of the source or drain is connected to a wiring SL. One of the source or drain of the transistor 92 is connected to the other electrode of the capacitor 95 and one electrode of the inorganic light-emitting element 100, and the other of the source or drain is connected to a wiring that supplies a potential Va. The other electrode of the inorganic light-emitting element 100 is connected to a wiring that supplies a potential Vc. A node that is connected to one of the source or drain of the transistor 91, the gate of the transistor 92, and one electrode of the capacitor 95 is referred to as a node N96. A node that is connected to one of the source or drain of the transistor 92, the other electrode of the capacitor 95, and one electrode of the inorganic light-emitting element 100 is referred to as a node N97.

[0249] Here, the case where the potential Va is a high power supply potential and the potential Vc is a low power supply potential will be described. The potential Va and the potential Vc can each be a common potential for multiple pixels pix. The capacitor 95 also functions as a storage capacitor for storing the potential of the node N96.

[0250] The transistor 91 has a function of controlling the supply of the potential of the wiring SL to the node N97. Specifically, by controlling the potential of the wiring GL to turn on the transistor 91, the potential of the wiring SL corresponding to the video signal is supplied to the node N96, and writing to the pixel pix is ​​performed. After that, by controlling the potential of the wiring GL to turn off the transistor 91, the potential of the node N96 is maintained.

[0251] The amount of current flowing between the source and drain of the transistor 92 is controlled according to the voltage between the nodes N96 and N97, and the inorganic light-emitting element 100 emits light at a luminance according to the amount of current. This makes it possible to control the gradation of the pixel pix. It is preferable that the transistor 92 be operated in a saturation region.

[0252] Here, the transistor 91 and the transistor 92 may be provided in the same layer or may be stacked. By providing the transistor 91 and the transistor 92 in the same layer, the transistors 91 and 92 can be manufactured at the same time, thereby shortening the manufacturing process of the display device. Alternatively, by providing the transistor 91 and the transistor 92 in a stacked state, the integration degree of the display device can be increased.

[0253] 13B, a configuration having two transistors (91 and 92) in a pixel pix is ​​preferable. However, one embodiment of the present invention is not limited to this, and a configuration having three or more transistors in a pixel pix is ​​also possible.

[0254] Fig. 13C shows a configuration example of a pixel pix that uses an inorganic light-emitting element as a display element, which is different from Fig. 13B. The pixel pix shown in Fig. 13C has a transistor 91, a transistor 92, a transistor 93, a capacitor 95, and an inorganic light-emitting element 100. In other words, the pixel pix shown in Fig. 13C is a pixel in which a transistor 93 for monitoring the amount of current flowing through the transistor 92 is added to the pixel pix shown in Fig. 13B.

[0255] The gate of the transistor 91 is connected to the wiring GL, one of the source or drain is connected to the gate of the transistor 92 and one electrode of the capacitor 95, and the other of the source or drain is connected to the wiring SL. The one of the source or drain of the transistor 92 is connected to the other electrode of the capacitor 95, one electrode of the inorganic light-emitting element 100, and one of the source or drain of the transistor 93, and the other of the source or drain is connected to a wiring that supplies a potential Va. The other electrode of the inorganic light-emitting element 100 is connected to a wiring that supplies a potential Vc. The gate of the transistor 93 is connected to the wiring GL, and the other of the source or drain is connected to the monitor line ML. A node that is connected to one of the source or drain of the transistor 91, the gate of the transistor 92, and one electrode of the capacitor 95 is referred to as node N96. A node that is connected to one of the source or drain of the transistor 92, the other electrode of the capacitor 95, one electrode of the inorganic light-emitting element LE, and one of the source or drain of the transistor 93 is referred to as node N97.

[0256] By performing the above operation sequentially for each wiring GL, the first frame of video can be displayed.

[0257] The wirings GL may be selected using either a progressive method or an interlaced method. The supply of video signals to the wirings SL may be performed using a dot-sequential driving method in which video signals are sequentially supplied to the wirings SL, or a line-sequential driving method in which video signals are simultaneously supplied to all wirings SL. Alternatively, video signals may be supplied sequentially to each of the multiple wirings SL.

[0258] Thereafter, in the second frame period, an image is displayed by the same operation as in the first frame period, whereby the image displayed in the pixel portion 401 is rewritten.

[0259] The semiconductor used in the transistor of the pixel pix can be an element of Group 14 such as silicon or germanium, a compound semiconductor such as gallium arsenide, an organic semiconductor, a metal oxide, etc. The semiconductor may be a non-single-crystal semiconductor (amorphous semiconductor, microcrystalline semiconductor, polycrystalline semiconductor, etc.) or a single-crystal semiconductor.

[0260] The transistor in each pixel pix preferably contains an amorphous semiconductor, particularly hydrogenated amorphous silicon (a-Si:H), in its channel formation region. Transistors using amorphous semiconductors can easily accommodate larger substrates, simplifying the manufacturing process for large-screen display devices compatible with 4K2K and 8K4K broadcasting, for example.

[0261] The transistors in the pixel pix can also be OS transistors, which contain metal oxide in their channel formation regions. OS transistors have higher field-effect mobility than transistors using hydrogenated amorphous silicon. Furthermore, they do not require the crystallization process required for transistors using polycrystalline silicon.

[0262] Furthermore, because an OS transistor has an extremely small off-state current, when an OS transistor is used as the transistor 91, a video signal can be held in the pixel pix for an extremely long period of time. This allows the frequency of updating the video signal to be set extremely low during periods when the video displayed on the pixel unit 401 does not change or changes only to a certain extent. The frequency of updating the video signal can be set to, for example, once per 0.1 seconds or less, once per second or less, or once per 10 seconds or less. In particular, when a large number of pixels pix are provided to support 4K2K broadcasting, 8K4K broadcasting, etc., omitting updating the video signal is effective in reducing power consumption.

[0263] 14 is a diagram illustrating a display device. The display device includes a substrate 10, a substrate 11, a functional layer 12, a metal oxynitride film 20, a pixel section 401, a plurality of terminals Vp, and a plurality of terminals Vc. The pixel section 401 includes a plurality of pixels Pix. The metal oxynitride film 20 functions as a common electrode, and a plurality of pixels Pix are formed on the common electrode. It is preferable that a cathode potential be applied to the common electrode.

[0264] The multiple terminals Vp are terminals for supplying signals to the respective pixels Pix. Some of the terminals Vp are connected to wiring SL, and the remaining terminals VP are connected to wiring GL. The multiple terminals Vc are connected to the metal oxynitride film 20, which functions as a common electrode. By providing multiple terminals Vc, the cathode potential of the inorganic light-emitting element 100 of each pixel Pix can be prevented from floating due to the influence of the resistance component of the metal oxynitride film 20.

[0265] The display device also has an inorganic light-emitting element forming layer 100L in which the inorganic light-emitting element 100 is formed, a capacitance forming layer 95L in which a capacitance 95 is formed, and a transistor forming layer 92L in which a transistor 92 is formed. The pixel Pix has the inorganic light-emitting element 100 formed in the inorganic light-emitting element forming layer 100L, the capacitance 95 formed in the capacitance forming layer 95L, and the transistor 92 formed in the transistor forming layer 92L. The terminal Vp is electrically connected to the wiring of the transistor forming layer.

[0266] Note that bumps can be provided on the terminals Vp and Vc. Although not shown in FIG. 14, it is preferable to bond the drive circuits 402 and 403 together. This makes it possible to create a small, high-definition display device. Furthermore, by bonding the drive circuits 402 and 403 together via bumps, the number of components can be reduced. The above-described display device can be used in a head mounted display (HMD). As an example, it is preferable to use it in a goggle-type display device or an eyeglass-type display device.

[0267] 15A shows a perspective view of a glasses-type information terminal 900. The information terminal 900 includes a pair of display panels 901, a pair of housings (housing 902a and housing 902b), a pair of optical members 903, a pair of mounting portions 904, and the like.

[0268] The information terminal 900 can project an image displayed on the display panel 901 onto a display region 906 of the optical member 903. Furthermore, because the optical member 903 is translucent, the user can view the image displayed on the display region 906 superimposed on a transmitted image viewed through the optical member 903. Therefore, the information terminal 900 is an information terminal capable of AR display or VR display. The display unit 14 described in the previous embodiment can include not only the display panel 901 but also an optical member 903 including the display region 906, and an optical system having a lens 911, a reflector 912, and a reflective surface 913, which will be described later. A micro LED display is preferably used as the display panel 901. The display panel 901 can be an organic EL display, an inorganic EL display, a liquid crystal display, or the like. When the display panel 901 is a liquid crystal display, an inorganic light-emitting element 100 can be used as a light source functioning as a backlight.

[0269] The information terminal 900 is also provided with a pair of cameras 905 capable of capturing images in front of it and a pair of cameras 909 capable of capturing images toward the user. The cameras 905 are part of the components of a camera module. Providing multiple cameras 905 in the information terminal 900 is preferable because it allows ingredients and cooking utensils to be captured in three dimensions. However, the camera 905 in this embodiment is not limited to this. The information terminal 900 may be provided with only one camera 905. In this case, the camera 905 may be provided in the center of the front surface of the information terminal 900, or may be provided on the front surface of one of the housings 902a and 902b. Furthermore, two cameras 905 may be provided on the front surfaces of the housings 902a and 902b, respectively.

[0270] The camera 909 can detect the user's line of sight. Therefore, it is preferable to provide two cameras 909, one for the right eye and one for the left eye. However, if one camera can detect the line of sight of both eyes, only one camera 909 may be used. The camera 909 may also be an infrared camera that can detect infrared rays.

[0271] The housing 902a also includes a wireless communication device 907 that can supply a video signal or the like to the housing 902. The wireless communication device 907 preferably includes a communication module and communicates with a database. Note that instead of or in addition to the wireless communication device 907, a connector to which a cable 910 that supplies a video signal or a power supply potential can be connected may be provided. The housing 902 may also include an acceleration sensor, a gyro sensor, or the like to detect the orientation of the user's head and display an image corresponding to that orientation in the display area 906. The housing 902 preferably includes a battery that can be charged wirelessly or via a wired connection. Note that the battery is preferably incorporated into the pair of attachment portions 904.

[0272] An integrated circuit 908 is also provided in the housing 902b. The integrated circuit 908 has a controller, a processor, a memory, an audio controller, etc., which are not shown in Fig. 15, and also has a camera 905, a wireless communication device 907, a pair of display panels 901, a microphone, a speaker, etc. Note that the information terminal 900 preferably has a function for controlling various components and a function for generating images. The integrated circuit 908 preferably has a function for generating a composite image for AR display or VR display.

[0273] Data can be communicated with external devices via the wireless communication device 907. For example, data transmitted from the outside can be output to the integrated circuit 908, which can then generate image data for AR or VR display based on the data. An example of data transmitted from the outside is data obtained by transmitting an image captured by the camera 905 to a database and analyzing the data in the database.

[0274] 15B, a method for projecting an image onto display area 906 of information terminal 900 will be described. A display panel 901, a lens 911, and a reflector 912 are provided inside housing 902. In addition, a portion of optical member 903 corresponding to display area 906 has a reflecting surface 913 that functions as a half mirror.

[0275] Light 915 emitted from display panel 901 passes through lens 911 and is reflected by reflector 912 toward optical member 903. Inside optical member 903, light 915 is repeatedly totally reflected at the end surface of optical member 903 and reaches reflecting surface 913, whereby an image is projected onto reflecting surface 913. This allows the user to view both light 915 reflected by reflecting surface 913 and transmitted light 916 that has passed through optical member 903 (including reflecting surface 913).

[0276] 15B shows an example in which the reflector 912 and the reflecting surface 913 each have a curved surface. This allows for greater freedom in optical design and allows for a thinner optical member 903 than when these surfaces are flat. Note that the reflector 912 and the reflecting surface 913 may also be flat.

[0277] A member having a mirror surface can be used for the reflector 912, and it is preferable that the reflector 912 has high reflectivity. Furthermore, a half mirror that utilizes the reflection of a metal film may be used for the reflector 913, but if a prism that utilizes total reflection is used, the transmittance of the transmitted light 916 can be increased.

[0278] Here, it is preferable that the housing 902 has a mechanism for adjusting the distance between the lens 911 and the display panel 901 and the angle therebetween. This makes it possible to perform pin adjustments and enlarge or reduce the size of an image. For example, the lens 911 or the display panel 901, or both, may be configured to be movable in the direction of the optical axis.

[0279] Furthermore, it is preferable that the housing 902 has a mechanism that can adjust the angle of the reflector 912. By changing the angle of the reflector 912, it is possible to change the position of the display area 906 where an image is displayed. This makes it possible to position the display area 906 in an optimal position according to the position of the user's eyes.

[0280] The display device of one embodiment of the present invention can be applied to the display panel 901. Thus, the information terminal 900 can display images with extremely high resolution.

[0281] This embodiment mode can be combined as appropriate with the descriptions of other embodiment modes and examples.

[0282] (Fourth embodiment) In this embodiment, an electronic device according to one embodiment of the present invention using the display device described in the above embodiment will be described with reference to drawings.

[0283] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound reproduction devices.

[0284] The electronic device of one embodiment of the present invention may have an antenna. By receiving a signal through the antenna, an image, information, or the like can be displayed on the display portion. Note that the display portion can be formed of a display device, and therefore the display portion can also be called a display device. Furthermore, when the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0285] An electronic device according to one embodiment of the present invention may have a sensor (including a function for measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0286] The electronic device of one embodiment of the present invention can have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display portion, a touch panel function, a function to display a calendar, date, time, etc., a function to execute various software (programs), a wireless communication function, a function to read programs or data recorded on a recording medium, etc.

[0287] 16A shows an example of a television device. A television device 7100 has a display unit 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0288] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0289] 16A can be operated using an operation switch provided on the housing 7101 or a separate remote control 7111. Alternatively, the display unit 7000 may be provided with a touch sensor, and operation may be performed by touching the display unit 7000 with a finger, a slider, or the like. The remote control 7111 may have a display unit that displays information output from the remote control 7111. The channel and volume can be controlled using the operation keys or touch panel provided on the remote control 7111, and the video displayed on the display unit 7000 can be controlled.

[0290] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. In addition, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, between receivers, etc.) information communication.

[0291] 16B shows a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. A display portion 7000 is incorporated in the housing 7211.

[0292] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0293] 16C and 16D show an example of digital signage.

[0294] 16C includes a housing 7301, a display unit 7000, a speaker 7303, and the like. It may also include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0295] 16D shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0296] 16C and 16D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0297] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it will attract people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[0298] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000 but also allows the user to intuitively operate it. Furthermore, when used to provide information such as route information and traffic information, intuitive operation can improve usability.

[0299] 16C and 16D, it is preferable that digital signage 7300 or digital signage 7400 can wirelessly link with information terminal 7311 or information terminal 7411, such as a smartphone carried by a user. For example, advertising information displayed on display unit 7000 can be displayed on the screen of information terminal 7311 or information terminal 7411. Furthermore, by operating information terminal 7311 or information terminal 7411, the display on display unit 7000 can be switched.

[0300] Furthermore, it is also possible to run a game on the digital signage 7300 or the digital signage 7400 using the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller), thereby allowing an unspecified number of users to simultaneously participate in and enjoy the game.

[0301] Furthermore, the display device according to one embodiment of the present invention can be incorporated along the curved surface of the interior or exterior wall of a house or building, or the interior or exterior of a vehicle. Fig. 16E shows an example of mounting the display device according to one embodiment of the present invention on a vehicle.

[0302] 16E illustrates a configuration example of a vehicle including a display unit 5001. A display device according to one embodiment of the present invention can be used as the display unit 5001. Note that although FIG. 16E illustrates an example in which the display unit 5001 is installed in a right-hand drive vehicle, the present invention is not limited thereto, and the display unit can also be installed in a left-hand drive vehicle. In this case, the left and right positions of the configuration illustrated in FIG. 16E are reversed.

[0303] 16E shows a dashboard 5002, a steering wheel 5003, a windshield 5004, and the like that are arranged around the driver's seat and passenger seat. A display unit 5001 is arranged at a predetermined position on the dashboard 5002, specifically around the driver, and has a roughly T-shape. While FIG. 16E shows an example in which one display unit 5001 formed using a plurality of display panels 5007 (display panels 5007a, 5007b, 5007c, 5007d) is provided along the dashboard 5002, the display unit 5001 may be arranged in multiple locations.

[0304] The plurality of display panels 5007 may be flexible. In this case, the display unit 5001 can be processed into a complex shape, and it is possible to easily realize a configuration in which the display unit 5001 is provided along a curved surface such as the dashboard 5002, or a configuration in which the display area of ​​the display unit 5001 is not provided on the connection portion of the steering wheel, the display portion of the instrument, the air vent 5006, or the like.

[0305] In addition, a plurality of cameras 5005 for capturing images of the rear and lateral situations may be provided outside the vehicle. Although Fig. 16E shows an example in which cameras 5005 are provided instead of side mirrors, both side mirrors and cameras may be provided.

[0306] A CCD camera, a CMOS camera, or the like can be used as the camera 5005. In addition to these cameras, an infrared camera may also be used in combination. The output level of an infrared camera increases as the temperature of the subject increases, so it is possible to detect or extract living organisms such as people and animals.

[0307] The images captured by the camera 5005 can be output to one or more of the display panels 5007. This display unit 5001 is used mainly to assist driving of the vehicle. By capturing images of the rear and lateral conditions with a wide angle of view using the camera 5005 and displaying the images on the display panel 5007, the driver can see blind spots, thereby preventing accidents from occurring.

[0308] Furthermore, a range image sensor may be provided on the roof of the vehicle, and an image obtained by the range image sensor may be displayed on the display unit 5001. As the range image sensor, an image sensor or a LIDAR (Light Detection and Ranging) may be used. By displaying the image obtained by the image sensor and the image obtained by the range image sensor on the display unit 5001, more information can be provided to the driver, and driving assistance can be provided.

[0309] Display unit 5001 may also have a function for displaying map information, traffic information, television images, DVD images, etc. For example, display panels 5007a, 5007b, 5007c, and 5007d can be used as a single display screen to display large map information. The number of display panels 5007 can be increased depending on the images to be displayed.

[0310] Furthermore, the images displayed on display panels 5007a, 5007b, 5007c, and 5007d can be freely set according to the driver's preferences. For example, television images and DVD images can be displayed on left display panel 5007d, map information can be displayed on central display panel 5007b, instruments can be displayed on right display panel 5007c, and audio equipment can be displayed on display panel 5007a near the gearbox (between the driver's seat and passenger seat). Furthermore, by combining multiple display panels 5007, a fail-safe function can be added to display unit 5001. For example, even if one display panel 5007 fails for some reason, the display area can be changed and another display panel 5007 can be used for display.

[0311] This embodiment mode can be combined as appropriate with the descriptions of other embodiment modes and examples. [Example]

[0312] This example describes the results of evaluating the crystallinity and orientation of metal nitride films formed on metal oxynitride films using the method described in the above embodiment. Specifically, multiple samples (Samples 1 to 5) were prepared by depositing metal oxynitride films on substrates using the method described in the above embodiment, and out-of-plane measurement and φ scan were performed on each sample using X-rays. For Samples 1 and 2, a metal oxynitride film was formed on a substrate, and a metal nitride film was formed on the metal oxynitride film. For Sample 3, a metal oxide film was formed on a substrate, and a metal nitride film was formed on the metal oxide film. For Samples 4 and 5, metal nitride films were formed on substrates as comparisons with Samples 1 to 3.

[0313] <Sample preparation method> First, a description will be given of the manufacturing methods of Samples 1 to 3. Samples 4 and 5 were manufactured as comparisons with Samples 1 to 3.

[0314] Samples 1 to 3 were fabricated using the method for fabricating a metal oxynitride film described in Embodiment 1. Specifically, a single crystal substrate was prepared, and a metal oxynitride film was formed on the substrate by sputtering using an oxide target after introducing a gas into a reaction chamber. Note that, before forming the metal oxynitride film on the substrate, no pretreatment such as high-temperature air annealing or vacuum annealing was performed on the substrate. Furthermore, no heat treatment was performed on the formed metal oxynitride film.

[0315] The deposition conditions for the metal oxynitride films common to Samples 1 to 3 were a deposition pressure of 0.4 Pa, a deposition power of 200 W, and a distance between the oxide target and the substrate of 130 mm.

[0316] The single crystal substrates used to fabricate each sample will now be described. For sample 1, an a-plane sapphire substrate was prepared as the single crystal substrate. For samples 2 and 3, an yttria-stabilized zirconia (YSZ) substrate was prepared. The a-plane sapphire substrate had a (110) plane orientation, while the YSZ substrate had a (111) plane orientation. In this example, it was confirmed that the metal oxynitride film and indium tin oxide functioned as buffer layers even when substrates with different plane orientations were used.

[0317] Next, we will explain the oxide targets used in the fabrication of each sample. Samples 1 and 2 used an In-Ga-Zn oxide target with an atomic ratio of In:Ga:Zn=4:2:4.1 as the oxide target. Therefore, the metal oxynitride films of Samples 1 and 2 are In-Ga-Zn oxynitride films (referred to as IGZON). Sample 3 used indium tin oxide as the oxide target.

[0318] Next, we will explain the gas (also called film-forming gas) introduced into the reaction chamber. Nitrogen gas (N2) at 45 sccm was used as the film-forming gas for Sample 1 and Sample 2. Furthermore, a mixed gas of oxygen gas (O2) at 5 sccm and argon gas (Ar) at 40 sccm was used as the film-forming gas for Sample 3.

[0319] Next, the deposition conditions for the metal nitride films common to Samples 1 to 3 were a deposition pressure of 0.4 Pa, a deposition power of 200 W, and a distance between the nitride target and the substrate of 130 mm. Note that a metal oxynitride film was deposited on the substrate of Samples 1 and 2, and the metal oxynitride film was an In-Ga-Zn oxynitride film. Also, a metal oxide film was deposited on the substrate of Sample 3, and the metal oxide film was an indium tin oxide film.

[0320] Next, the nitride targets used to prepare each sample will be described. As the nitride target, a sintered GaN target was used for Samples 1 to 3.

[0321] Next, the gas (also referred to as film formation gas) introduced into the reaction chamber will be described. As the film formation gas for Samples 1 to 3, nitrogen gas (N2) was used at 45 sccm.

[0322] Note that samples 1 to 3 were not subjected to pre-treatment or heat treatment after film formation.

[0323] Next, the substrate temperature during the formation of the metal oxynitride film will be described. The substrate temperature for Samples 1 to 3 was set to 200°C.

[0324] Next, the substrate temperature during the deposition of the metal nitride film will be described. The substrate temperature for Samples 1 to 3 was set to 300°C.

[0325] Samples 1 to 3 were fabricated as described above. The processing conditions for each sample are summarized in Tables 1 and 2. Table 1 shows the processing conditions for fabricating a metal oxynitride film, and Table 2 shows the processing conditions for fabricating a metal nitride film. For Sample 4, a metal nitride film was fabricated on an a-plane sapphire substrate, and for Sample 5, a metal nitride film was fabricated on an yttria-stabilized zirconia (YSZ) substrate.

[0326] [Table 1]

[0327] [Table 2]

[0328] For each of the prepared samples 1 to 5, out-of-plane measurements and φ scans using X-rays were performed. The X-ray measurement device used was a D8 DOSCOVER X-ray diffractometer manufactured by Bruker Japan, and the detector used was a zero-dimensional detector. In this example, the results of the out-of-plane measurements and φ scans are shown in the figures.

[0329] In each figure showing the results of the φ scan, the horizontal axis represents the angle φ [°] (expressed as phi (deg.)), and the vertical axis represents the peak intensity (expressed as Intensity (au)). In addition, to evaluate the in-plane orientation, the full width at half maximum of the measured peak was evaluated.

[0330] As a result of performing a φ scan on each sample, six diffraction peaks were measured for each sample in this example, and it was therefore confirmed that the crystal structure of the metal nitride formed on the metal oxynitride in Samples 1 to 3 was a wurtzite structure.

[0331] In this example, the results of the out-of-plane measurement, the φ scan (denoted as phi scan(GaN)), and the φ scan of the substrate used to fabricate the samples (denoted as phi scan(substrate)) are shown in FIG. 17. The results of measuring the full width at half maximum (FWHM) from the φ scan of Samples 1 to 5 are shown in Table 3. Note that a description of the results of the out-of-plane measurement and the φ scan of the substrate used to fabricate the samples will be omitted.

[0332] [Table 3]

[0333] Next, the evaluation results of Samples 1 to 3 will be described in detail.

[0334] <Evaluation of Sample 1> The measurement results for Sample 1 are shown in Figure 17. For Sample 1, an In-Ga-Zn oxynitride film was grown on an a-plane sapphire substrate, and a metal nitride film (GaN) was further grown on the In-Ga-Zn oxynitride film.

[0335] Six diffraction peaks were observed in the phi scan of Sample 1. For comparison, Sample 4 was also prepared. Sample 4 was a metal nitride film (GaN) formed on an a-plane sapphire substrate. Six diffraction peaks were confirmed for both Sample 1 and Sample 4, indicating that both have six-fold symmetry.

[0336] That is, it can be seen that the (101) plane of the metal nitride film (GaN) of Sample 1 has six-fold symmetry, and that the metal nitride film (GaN) of Sample 1 is in-plane oriented. Furthermore, since the angle between the (002) plane and the (101) plane in a wurtzite structure is approximately 62°, the peak indicating six-fold symmetry obtained by performing a φ scan at this angle indicates that the crystal of the metal nitride film (GaN) of Sample 1 has a wurtzite structure. Therefore, it can be seen that the metal nitride film (GaN) of Sample 1 is a c-axis epitaxial film.

[0337] From the above, it can be seen that the metal nitride film of Sample 1 has a wurtzite structure and is epitaxially grown. The full width at half maximum (FWHM) of the diffraction peak of Sample 1 measured by φ scanning was 5.25. Therefore, the In-Ga-Zn oxynitride film is suitable as a buffer layer for growing a metal nitride film (GaN).

[0338] <Evaluation of Sample 2> The measurement results for Sample 2 are shown in Figure 17. For Sample 2, an In-Ga-Zn oxynitride film was fabricated on an yttria-stabilized zirconia (YSZ) substrate, and a metal nitride film (GaN) was further fabricated on the In-Ga-Zn oxynitride film.

[0339] Six diffraction peaks were observed in the phi scan of Sample 2. For comparison, Sample 5 was also prepared. Sample 5 was prepared by forming a metal nitride film (GaN) on an yttria-stabilized zirconia (YSZ) substrate. Six diffraction peaks were confirmed in both Sample 2 and Sample 5, indicating that both have a wurtzite structure.

[0340] That is, it can be seen that the (101) plane of the metal nitride film (GaN) of Sample 2 has six-fold symmetry, and that the metal nitride film (GaN) of Sample 2 is in-plane oriented. Furthermore, since the angle between the (002) plane and the (101) plane in a wurtzite structure is approximately 62°, the peak indicating six-fold symmetry obtained by performing a φ scan at this angle indicates that the crystal of the metal nitride film (GaN) of Sample 2 has a wurtzite structure. Therefore, it can be seen that the metal nitride film (GaN) of Sample 2 is a c-axis epitaxial film.

[0341] From the above, it can be seen that the metal nitride film of Sample 2 has a wurtzite structure and is epitaxially grown. The full width at half maximum of the diffraction peak of Sample 2 measured by φ scanning was 2.96. Therefore, the In-Ga-Zn oxynitride film is suitable as a buffer layer for growing a metal nitride film (GaN).

[0342] <Evaluation of Sample 3> The measurement results for Sample 3 are shown in Figure 17. For Sample 3, an indium tin oxide (ITO) film was fabricated on an yttria-stabilized zirconia (YSZ) substrate, and a metal nitride film (GaN) was further fabricated on the indium tin oxide (ITO) film.

[0343] As a result of the phi scan of sample 3, six diffraction peaks were observed, indicating that it has a wurtzite structure.

[0344] That is, it can be seen that the (101) plane of the metal nitride film (GaN) of Sample 3 has six-fold symmetry, and that the metal nitride film (GaN) of Sample 3 is in-plane oriented. Furthermore, since the angle between the (002) plane and the (101) plane in a wurtzite structure is approximately 62°, the peak indicating six-fold symmetry obtained by performing a φ scan at this angle indicates that the crystal of the metal nitride film (GaN) of Sample 3 has a wurtzite structure. Therefore, it can be seen that the metal nitride film (GaN) of Sample 3 is a c-axis epitaxial film.

[0345] From the above, it can be seen that the metal nitride film (GaN) of Sample 3 has a wurtzite structure and is epitaxially grown. The full width at half maximum of the diffraction peak of Sample 3 measured by φ scanning was 3.36. Therefore, the In-Ga-Zn oxynitride film is suitable as a buffer layer for growing a metal nitride film (GaN).

[0346] Hall effect measurements were performed on the carrier concentrations of the metal oxynitride films and metal oxide films used in Samples 1 to 3. The evaluation results of the Hall effect measurements are shown in Table 4. An example of a Hall effect measurement device is the ResiTest8310 resistivity / Hall measurement system (manufactured by Toyo Corporation). The ResiTest8310 resistivity / Hall measurement system is capable of AC (alternating current) Hall measurement, which changes the direction and magnitude of a magnetic field at a constant cycle and detects only the Hall voltage that appears in the sample in synchronization with this. This allows the detection of Hall voltage even in materials with low mobility and high resistivity.

[0347] For the evaluation samples, metal oxynitride films were fabricated on yttria-stabilized zirconia (YSZ) substrates using the conditions shown in Table 1. Table 3 shows the results of measuring the Hall effect of the evaluation samples. For comparison, indium tin oxide (ITO) films and In-Ga-Zn oxynitride films fabricated on yttria-stabilized zirconia (YSZ) substrates were also measured. Note that indium tin oxide (ITO) films are often used as transparent conductive films in display devices and lighting devices.

[0348] [Table 4]

[0349] The results of Hall effect measurements confirmed that the In-Ga-Zn oxynitride film functions as a conductive film equivalent to an indium tin oxide (ITO) film. Furthermore, it was confirmed that, in Sample 2, by fabricating a metal nitride film (GaN) on the In-Ga-Zn oxynitride film, a metal nitride film (GaN) with higher crystallinity than Sample 5 could be fabricated. This indicates that the In-Ga-Zn oxynitride film functions as a buffer layer for fabricating a metal nitride film (GaN). Furthermore, because the In-Ga-Zn oxynitride film has conductivity equivalent to that of indium tin oxide (ITO), it can function as an electrode for inorganic light-emitting devices.

[0350] The In-Ga-Zn oxynitride film can be formed by sputtering, and a metal nitride film (GaN) can be formed on the In-Ga-Zn oxynitride film by sputtering. A sputtering system with multiple sputtering targets can continuously form the In-Ga-Zn oxynitride film and the metal nitride film (GaN). Furthermore, the In-Ga-Zn oxynitride film and the metal nitride film (GaN) can be formed at low temperatures.

[0351] At least a part of the configurations, methods, and the like shown in this embodiment can be implemented in appropriate combination with other embodiment modes described in this specification. [Explanation of symbols]

[0352] : 10: substrate, 11: substrate, 12: functional layer, 12a: functional layer, 12b: functional layer, 12c: functional layer, 13: light-shielding layer, 14: display unit, 20: metal oxynitride film, 20a: crystal, 30: metal nitride film, 30a: crystal, 31: cladding layer, 32: active layer, 33: cladding layer, 34: conductor, 35: electrode, 36: electrode, 41: insulator, 43: insulator, 47: insulator, 47a: insulator, 48: insulator, 49: insulator, 51: insulator, 52: conductor, 54: conductor, 54a: magnet unit, 56: conductor, 56a: conductor, 56d: conductor, 58: terminal, 59: conductor Conductor, 59a: conductor, 59d: conductor, 61: insulator, 63: insulator, 65: insulator, 67: insulator, 69: insulator, 71: conductor, 71a: conductor, 71b: conductor, 72: conductor, 72a: conductor, 72b: conductor, 81: insulator, 83: insulator, 85: insulator, 87: insulator, 91: transistor, 92: transistor, 92A: transistor, 92B: transistor, 92L: transistor forming layer, 93: transistor, 95: capacitor, 95L: capacitor forming layer, 100: inorganic light emitting element, 100L: inorganic light emitting element forming layer, 101: reciprocal lattice point, 111 : reciprocal lattice point, 200: sputtering device, 201: film formation chamber, 202: substrate holder, 203: substrate, 204: sputtering target, 205: backing plate, 206: magnet unit, 206a: magnet unit, 206b: magnet unit, 207a: oscillation range, 207b: oscillation range, 400: display device, 401: pixel unit, 402: drive circuit, 403: drive circuit, 503: conductor, 503a: conductor, 503b: conductor, 518: conductor, 530: oxide, 530a: oxide, 530b: oxide, 540a: conductor, 540b : conductor, 542: conductor, 542a: conductor, 542b: conductor, 543a: region, 543b: region, 545: insulator, 552: insulator, 560: conductor, 560a: conductor, 560b: conductor, 900: information terminal, 901: display panel, 902: housing, 902a: housing, 902b: housing, 903: optical member, 904: mounting part, 905: camera, 906: display area, 907: wireless communication device, 908: integrated circuit, 909: camera, 910: cable, 911: lens, 912: reflector, 913: reflective surface, 915: light, 916: transmitted light, 5001: display unit,5002: dashboard, 5003: steering wheel, 5004: windshield, 5005: camera, 5006: air vent, 5007: display panel, 5007a: display panel, 5007b: display panel, 5007c: display panel, 5007d: display panel, 7000: display unit, 7100: television device, 7101: housing, 7103: stand, 7111: remote control device, 7200: notebook personal computer, 7211: housing, 7212: keyboard, 7213: pointing device, 7214: external connection port, 7300: digital signage, 7301: housing, 7303: speaker, 7311: information terminal, 7400: digital signage, 7401: pillar, 7411: information terminal,

Claims

1. 1. A method of fabricating a device, comprising forming an epitaxially grown first film and an epitaxially grown second film on a substrate, the method comprising: a first step of forming the first film by a sputtering method using a zinc-containing, electrically conductive oxide target; a second step of depositing the second film on the first film by a sputtering method using a nitride target containing gallium and nitrogen and having electrical conductivity; In the first step, the first film is formed by setting the temperature of the substrate to 80° C. or more and 500° C. or less, and introducing a first gas in which the flow rate of nitrogen gas is 50% or more and 100% or less of the total flow rate; a second gas supplying step of supplying a nitrogen gas to the second film, the second gas supplying step being performed at a temperature of the substrate of 80°C or more and 500°C or less, and a flow rate of the nitrogen gas being 80% or more and 100% or less of the total flow rate;

2. A semiconductor device comprising a first film which is an epitaxial film and a second film which is an epitaxial film on the first film, the first film comprises indium, zinc, oxygen, and nitrogen; the second film comprises gallium and nitrogen; the second film has a wurtzite structure; The inorganic light-emitting device, wherein the first film functions as one of the electrodes.

Images