Indication device

Abstract

To provide a metal oxide film containing crystalline parts. To provide a metal oxide film with high physical stability. To provide a metal oxide film with improved electrical properties. A metal oxide that can increase field effect mobility. We provide oxide films. We provide highly reliable semiconductor devices using metal oxide films. [Solution] The metal oxide film is made of indium, M (where M is Al, Ga, Y, or Sn), and It contains zinc. Furthermore, in X-ray diffraction in a direction perpendicular to the film surface, the crystal structure causes the following It has a region where a peak in folding intensity is observed. Furthermore, transmission electron microscopy in a cross-section perpendicular to the film surface... Multiple crystalline regions are observed in the mirror image. The proportion of the region other than these crystalline regions is 20% or more. It is less than 0%.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a metal oxide film and a method for producing the same. This relates to semiconductor devices using oxide films.

[0002] In this specification, a semiconductor device is defined as a device that can function by utilizing semiconductor properties. The term refers to devices in general, and transistors, semiconductor circuits, etc., are examples of semiconductor devices. Devices, memory devices, imaging devices, electro-optical devices, power generation devices (thin-film solar cells, organic thin-film solar cells) Electronic equipment may include semiconductor devices, etc. [Background technology]

[0003] Oxide semiconductors are attracting attention as semiconductor materials applicable to transistors. For example, In Patent Document 1, multiple oxide semiconductor layers are stacked, and among the multiple oxide semiconductor layers, The composition of the oxide semiconductor layer that forms the channel contains indium and gallium, and indium By making the composition of greater than that of gallium, the field-effect mobility (simply mobility, or A semiconductor device with improved μFE (sometimes referred to as μFE) has been disclosed.

[0004] Furthermore, Non-Patent Document 1 describes an oxide semiconductor having indium, gallium, and zinc. In 1-x Ga 1+x O3(ZnO) m (x is a number satisfying -1 ≤ x ≤ 1, and m is a natural number) It is disclosed that it has a homologous phase represented by [formula]. Furthermore, Non-Patent Document 1 discloses [formula]. The solid solution range of the homologous phase is disclosed. For example, the solid solution region of the homologous phase when m=1 is x from -0.33 to 0.0 The range is 8, and the solid solution region of the homologous phase when m=2 is x from -0.68 to 0.32 It is within the range. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-7399 [Non-patent literature]

[0006] [Non-Patent Document 1] M. Nakamura, N. Kimizuka, and T. Mohri, "The Phase Relations in the In2O3-Ga2ZnO4-ZnO System at 1350℃", J. Solid State Chem., 1991, Vol.93, pp.298-315 [Overview of the project] [Problems that the invention aims to solve]

[0007] One aspect of the present invention aims to provide a metal oxide film containing crystalline portions. One of its objectives is to provide a metal oxide film with high physical stability. Alternatively, electrical special One of the objectives is to provide a metal oxide film with improved properties. Alternatively, the field effect mobility is One of the objectives is to provide a metal oxide film with enhanced properties. Alternatively, a novel metal oxide film One of the objectives is to provide a reliable semiconductor with a metal oxide film applied. One of the objectives is to provide a body device.

[0008] Furthermore, one aspect of the present invention provides a metal oxide film that can be formed at low temperatures and has high physical stability. One of the objectives is to provide a semiconductor device that can be formed at low temperatures and is highly reliable. One of the challenges is to provide it.

[0009] Alternatively, one aspect of the present invention provides a flexible apparatus to which a metal oxide film is applied. This will be one of the challenges.

[0010] Furthermore, the description of these problems does not preclude the existence of other problems. One approach does not require that all of these issues be resolved. The title can be extracted from descriptions such as the specification, drawings, and claims. [Means for solving the problem]

[0011] One aspect of the present invention relates to indium, M (where M is Al, Ga, Y, or Sn), and zinc It is a metal oxide film containing [a specific element]. Furthermore, in X-ray diffraction perpendicular to the film surface, the crystal structure is [details omitted]. It has a region where a peak in diffraction intensity caused by the diffraction is observed. Furthermore, the transparency in a cross-section perpendicular to the film surface is also observed. Multiple crystalline regions are observed in the electron microscope image. The proportion of the region other than these crystalline regions is 2 It is between 0% and 60%, or between 25% and less than 100%.

[0012] Furthermore, the proportion of the above-mentioned multiple crystalline portions in which the c-axis is oriented in the film thickness direction is distributed in other directions. It is preferable that this ratio is higher than the proportion of the crystalline portion.

[0013] Furthermore, the first image obtained by fast Fourier transforming the cross-sectional TEM image shows periodicity. In the second image, which is obtained by inverse Fourier transform after applying a mask that preserves the range, the remaining from the original image The percentage of the area remaining after subtracting the existing image is 20% or more but less than 60%, or 25% or more but 100%. It is preferable to have a region that is less than [a certain value].

[0014] Furthermore, the sample was thinned to a thickness of 10 nm to 50 nm, and the probe diameter was set to 50 nm or larger. In electron diffraction in a direction perpendicular to the cross-section, a ring-shaped diffraction pattern and a ring-shaped A first electron diffraction pattern having two first spots at positions overlapping with the diffraction pattern. In electron diffraction where a n was observed and the probe diameter was set to 0.3 nm or more and 5 nm or less, A second electron beam having a first spot and a plurality of second spots distributed in the circumferential direction. It is preferable that the region has a diffraction pattern that can be observed.

[0015] Furthermore, the two first spots are observed symmetrically with respect to the center, and the most prominent of the first spots The angle between the first straight line passing through the point of high brightness and the center, and the normal direction of the film surface is 0 degrees or more. It is preferable to have a region where the temperature is 0 degrees or lower.

[0016] Furthermore, in the first electron diffraction pattern, a second straight line perpendicular to the first straight line and a ring The brightness of the ring-shaped diffraction pattern at the intersection with the first spot It is preferable to have a region with a brightness smaller than that of [the specified value].

[0017] Furthermore, the brightness of the first spot is at the intersection of the second straight line and the ring-shaped diffraction pattern. The brightness of the ring-shaped diffraction pattern has a region that is greater than 1x and less than or equal to 9x. It is preferable to do so.

[0018] One aspect of the present invention relates to indium, M (where M is Al, Ga, Y, or Sn), and zinc. It is a metal oxide film containing [a specific element]. Furthermore, in X-ray diffraction in a direction perpendicular to the film surface, the crystal structure is [details omitted]. It has a region where a peak in diffraction intensity due to the above is observed. Furthermore, from 10 nm to 50 nm The sample was thinned to the thickness shown below, and an electron beam was applied perpendicular to the cross-section with a probe diameter of 50 nm or more. In diffraction, there is a ring-shaped diffraction pattern and two points at the position where the ring-shaped diffraction pattern overlaps. A first electron diffraction pattern having a first spot and a probe diameter was observed. In electron diffraction with a wavelength of 0.3 nm to 5 nm, the first spot and the circumferential part are separated. A region in which a second electron diffraction pattern having multiple second spots is observed. To possess.

[0019] Furthermore, the first spot described above has a shape that extends in the circumferential direction, and the circumference of the first spot The angle between the two lines passing through each of the two ends of the direction and the center of the electron diffraction pattern is It is preferable that the temperature be within 45 degrees.

[0020] Another aspect of the present invention relates to a semiconductor having a semiconductor layer, a gate insulating layer, and a gate. The device is characterized in that the semiconductor layer includes the above-mentioned metal oxide film. [Effects of the Invention]

[0021] According to one aspect of the present invention, a metal oxide film containing crystalline portions can be provided. Alternatively, the physical properties can be stabilized. We can provide highly qualitative metal oxide films. Or, we can provide novel metal oxide films. This enables the provision of highly reliable semiconductor devices using metal oxide films.

[0022] Furthermore, according to one aspect of the present invention, a metal oxide that can be formed at low temperatures and has high physical stability is available. We can provide films, or semiconductor devices that can be formed at low temperatures and are highly reliable.

[0023] Alternatively, according to one aspect of the present invention, a metal oxide film is applied to a flexible device. It can be used. [Brief explanation of the drawing]

[0024] [Figure 1] XRD measurement results of metal oxide films. [Figure 2] Cross-sectional view of a metal oxide film. [Figure 3] Electron diffraction pattern of a metal oxide film. [Figure 4] Electron diffraction pattern of a metal oxide film. [Figure 5] Electron diffraction pattern of a metal oxide film. [Figure 6] Electron diffraction pattern of a metal oxide film. [Figure 7] Electron diffraction pattern and brightness profile of a metal oxide film. [Figure 8] Relative brightness estimated from the electron diffraction pattern of a metal oxide film. [Figure 9] Electron diffraction pattern of a metal oxide film. [Figure 10] Measurement results of fluctuations in the orientation of the crystalline portion of a metal oxide film. [Figure 11] Cross-sectional view of a metal oxide film and cross-sectional view after image analysis. [Figure 12] The electrical characteristics of a transistor. [Figure 13] TDS measurement results for metal oxide films. [Figure 14] SIMS measurement results of metal oxide films. [Figure 15] A model diagram used to calculate the movement of excess oxygen. [Figure 16] A model diagram used to calculate the movement of excess oxygen. [Figure 17] A model diagram used to calculate the movement of excess oxygen. [Figure 18] A model diagram used to calculate the movement of excess oxygen. [Figure 19] Calculation results explaining the ease with which excess oxygen moves. [Figure 20] A model diagram used to calculate the movement of oxygen deficiency. [Figure 21]A model diagram used to calculate the movement of oxygen deficiency. [Figure 22] Calculation results explaining how easily oxygen deficiencies can be transported. [Figure 23] ESR measurement results of metal oxide films. [Figure 24] CPM measurement results for metal oxide films. [Figure 25] A diagram showing the Id-Vg characteristics. [Figure 26] A diagram showing the Id-Vg characteristics. [Figure 27] A diagram showing the density of interface states. [Figure 28] A diagram showing the Id-Vg characteristics. [Figure 29] Calculation results of the defect levels of a transistor and the electrical characteristics of the transistor. [Figure 30] The electrical characteristics of a transistor. [Figure 31] A diagram illustrating the range of atomic ratios in oxide semiconductor films. [Figure 32] A diagram illustrating the crystal structure of InMZnO4. [Figure 33] A diagram illustrating the energy bands in a transistor that uses an oxide semiconductor film in the channel region. [Figure 34] Top view and cross-sectional view illustrating a semiconductor device. [Figure 35] Top view and cross-sectional view illustrating a semiconductor device. [Figure 36] A cross-sectional view illustrating a semiconductor device. [Figure 37] A cross-sectional view illustrating a semiconductor device. [Figure 38] A cross-sectional view illustrating a semiconductor device. [Figure 39] A cross-sectional view illustrating a semiconductor device. [Figure 40] A cross-sectional view illustrating a semiconductor device. [Figure 41] A cross-sectional view illustrating a semiconductor device. [Figure 42] A cross-sectional view illustrating a semiconductor device. [Figure 43] A cross-sectional view illustrating a semiconductor device. [Figure 44]A cross-sectional view illustrating a semiconductor device. [Figure 45] A diagram illustrating the band structure. [Figure 46] Top view and cross-sectional view illustrating a semiconductor device. [Figure 47] Top view and cross-sectional view illustrating a semiconductor device. [Figure 48] Top view and cross-sectional view illustrating a semiconductor device. [Figure 49] Top view and cross-sectional view illustrating a semiconductor device. [Figure 50] A cross-sectional view illustrating a semiconductor device. [Figure 51] A cross-sectional view illustrating a semiconductor device. [Figure 52] Top view and cross-sectional view illustrating a semiconductor device. [Figure 53] A diagram illustrating the cross-section of a semiconductor device. [Figure 54] A diagram illustrating the cross-section of a semiconductor device. [Figure 55] A diagram illustrating the cross-section of a semiconductor device. [Figure 56] A top view showing one embodiment of a display device. [Figure 57] A cross-sectional view showing one embodiment of a display device. [Figure 58] A cross-sectional view showing one embodiment of a display device. [Figure 59] A cross-sectional view showing one embodiment of a display device. [Figure 60] A cross-sectional diagram illustrating the method for fabricating the EL layer. [Figure 61] A conceptual diagram illustrating a droplet dispensing device. [Figure 62] A cross-sectional view showing one embodiment of a display device. [Figure 63] A cross-sectional view showing one embodiment of a display device. [Figure 64] Diagram illustrating the top view and cross-section of a semiconductor device. [Figure 65] A diagram illustrating the cross-section of a semiconductor device. [Figure 66] Block diagrams and circuit diagrams illustrating the display device. [Figure 67] A circuit diagram and timing chart illustrating one aspect of the present invention. [Figure 68] A graph and a circuit diagram illustrating one aspect of the present invention. [Figure 69] A circuit diagram and timing chart illustrating one aspect of the present invention. [Figure 70] A circuit diagram and timing chart illustrating one aspect of the present invention. [Figure 71] A block diagram, a circuit diagram, and a waveform diagram illustrating one aspect of the present invention. [Figure 72] A circuit diagram and timing chart illustrating one aspect of the present invention. [Figure 73] A circuit diagram illustrating one aspect of the present invention. [Figure 74] A circuit diagram illustrating one aspect of the present invention. [Figure 75] A diagram illustrating the display module. [Figure 76] A diagram illustrating electronic devices. [Figure 77] A diagram illustrating electronic devices. [Figure 78] A perspective view illustrating the display device. [Modes for carrying out the invention]

[0025] Embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description. Without departing from the spirit and scope of the present invention, its form and details may be modified in various ways. Those skilled in the art will readily understand what is possible. Therefore, the present invention is as shown in the following embodiments. It should not be interpreted as being limited to the contents described herein.

[0026] In the configuration of the invention described below, the same part or part having a similar function is The same reference numerals are used consistently across different drawings, and explanations of their repetition are omitted. When referring to the function of [this], the hatch pattern is the same, and sometimes no specific symbol is assigned.

[0027] In each figure described herein, the size, layer thickness, or area of ​​each component is as follows: It may be exaggerated for clarity. Therefore, it is not necessarily limited to that scale. stomach.

[0028] In this specification, ordinal numbers such as "the first," "the second," etc., are used to avoid confusion of constituent elements. This is added for the purpose of providing a numerical limit, and is not intended to limit the number of items.

[0029] A transistor is a type of semiconductor device that amplifies current and voltage, and controls conduction or non-conductivity. It is possible to realize controlled switching operations, etc. Transistors in this specification are , IGFET(Insulated Gate Field Effect Trans istors and thin-film transistors (TFTs) ) includes.

[0030] Furthermore, the "source" and "drain" functions are used when employing transistors with different polarities. For example, the direction of the current may change during circuit operation. Therefore, in this specification, the terms "source" and "drain" may be used interchangeably. It is assumed that this is possible.

[0031] In this specification and elsewhere, "metal oxide" refers to a metal in a broad sense. It is an oxide. Metal oxides are oxide insulators and oxide conductors (including transparent oxide conductors). ), oxide semiconductor (also called Oxide Semiconductor or simply OS) They are classified into categories such as the following. For example, when a metal oxide is used in the active layer of a transistor, the metal Oxides are sometimes referred to as oxide semiconductors. Therefore, when referring to an OS FET, Therefore, it can be rephrased as a transistor having a metal oxide or oxide semiconductor.

[0032] Furthermore, in this specification, metal oxides containing nitrogen are also referred to as metal oxides (metal oxides). They are sometimes collectively referred to as metal oxynitrides (metal oxides). Also, metal oxides containing nitrogen are sometimes called metal oxynitrides (metal oxides). It may also be called tal oxynitride.

[0033] Furthermore, in this specification, etc., CAAC (c-axis aligned crystal l) and when referring to CAC (cloud aligned composite) There is. Note that CAAC represents one example of a crystal structure, and CAC represents one of the functions or components of the material. This illustrates an example.

[0034] Furthermore, in this specification, CAC-OS or CAC-metal oxide is defined as follows: Some parts of the material have the function of a conductor, while other parts of the material have the function of a dielectric (or insulator). Furthermore, the material as a whole possesses semiconductor functionality. Note that CAC-OS or CAC-m When ethanol oxide is used in the active layer of a transistor, the conductor acts as a carrier. A dielectric material has the function of conducting electrons (or holes), and a dielectric material does not conduct electrons that act as carriers. It possesses the ability to function as both a conductor and a dielectric, with each function acting complementaryly. By doing so, the switching function (the function to turn on / off) is controlled by CAC-OS or It can be applied to CAC-metal oxide. CAC-OS or CAC- In metal oxides, separating each function allows for the optimal performance of both functions. It can be maximized.

[0035] Furthermore, in this specification, CAC-OS or CAC-metal oxide is defined as follows: It has a conductive region and a dielectric region. The conductive region has the functions of a conductor as described above, and the dielectric region has the functions of a dielectric. The material region has the dielectric function described above. Furthermore, within the material, there is a conductive region and a dielectric region. The regions may be separated at the nanoparticle level. Furthermore, there are conductive regions and dielectric regions. These can be unevenly distributed within the material. Also, the conductive region may appear blurred around the edges. They may sometimes be observed connected in a do-like pattern.

[0036] In other words, CAC-OS or CAC-metal oxide is a matrix composite Material (matrix composite), or metal matrix composite material (metal It can also be called a matrix composite.

[0037] Furthermore, in CAC-OS or CAC-metal oxide, the conductive region and The dielectric region is defined as being between 0.5 nm and 10 nm, preferably between 0.5 nm and 3 nm. They may be dispersed in the material in sizes smaller than m.

[0038] (Embodiment 1) One aspect of the present invention is a metal oxide film comprising two types of crystalline parts. The crystalline portion (also called the crystal portion) is the direction in the thickness direction of the film (the direction of the film surface, the surface on which the film is formed, or the direction perpendicular to the surface of the film). This is a crystalline part that has orientation (also called the direction). The other part of the crystalline part (also called the second crystalline part) This is a crystalline portion that is oriented in various directions without having a specific orientation. A metal according to one aspect of the present invention The oxide film contains a mixture of these two types of crystalline regions.

[0039] For the sake of simplicity, here we will refer to the crystalline portion having a specific orientation as the first crystalline portion. The crystalline portion that does not have orientation is explained separately as the second crystalline portion, but these are related to crystallinity and crystal structure. In some cases, there is no difference in size or other characteristics, making them indistinguishable. Therefore, in one aspect of the present invention, a metallic acid These can also be expressed without distinction. That is, metal acids according to one embodiment of the present invention The crystalline film has multiple crystalline regions, among which crystals are oriented perpendicular to the surface of the film. This can also be described as a film in which there are more crystalline parts than crystalline parts oriented in other directions.

[0040] The first crystalline portion has specific crystal planes that are oriented with respect to the thickness direction of the film. For a metal oxide film containing a first crystalline portion, such as the above, in a direction approximately perpendicular to the upper surface of the film When performing X-ray diffraction (XRD) measurements, a predetermined diffraction angle is obtained. A diffraction peak originating from the first crystal region is observed at (2θ). Note the height of the diffraction peak. (Strength) increases as the proportion of the first crystalline portion contained in the film increases, and the crystallinity of the film It can also serve as an indicator for gauging that.

[0041] A metal oxide film according to one aspect of the present invention is measured by a transmission electron microscope in a cross-section in the film thickness direction. Multiple crystalline regions are observed in the observed image. Of these multiple crystalline regions, one perpendicular to the c-axis. The first crystalline portion, in which the crystal planes are oriented in the thickness direction of the film, is more numerous than the crystalline portion oriented in other directions. It is observed that...

[0042] Furthermore, in metal oxide films, the region excluding the crystalline portion observed by transmission electron microscopy is 20% or more but less than 100%, preferably 20% or more but 80% or less, more preferably 20% or more It is preferable that it be 60% or less. Alternatively, the c-axis is the membrane as observed by a transmission electron microscope. The region excluding the first crystal portion oriented in the thickness direction is 20% to 60%, preferably 3 It is preferable that the concentration is between 0% and 50%. At this ratio, clear bonding occurs in the metal oxide film. The presence of regions other than the crystalline area can improve the oxygen permeability of the metal oxide film. Therefore, when a treatment is applied to supply oxygen to the metal oxide film, the effect of reducing oxygen deficiency is enhanced. Therefore, such metal oxide films can be used in semiconductor devices such as transistors. By applying this technology, it is possible to realize an extremely reliable semiconductor device.

[0043] Furthermore, a metal acid containing a first crystalline portion with orientation and a second crystalline portion without orientation. Transistors with a crystalline film applied exhibit an extremely high proportion of the first crystalline region, which has orientation. Compared to transistors with metal oxide films applied (for example, 75% or greater than 80%). This allows for high field-effect mobility, especially under low gate voltage conditions. It has features such as being able to lower the drive voltage and facilitating high-frequency driving. Unlike metal oxide films with extremely high crystallinity, these metal oxide films exhibit anisotropy in their ease of current flow. Because the properties are reduced, when applied to semiconductor devices, it reduces variations in electrical characteristics. can.

[0044] Furthermore, the metal oxide film according to one embodiment of the present invention is capable of electron diffraction in a direction perpendicular to the cross-section of the film. When this is performed, the electron diffraction pattern originating from the first crystal region and the electron diffraction pattern originating from the second crystal region are determined. A diffraction pattern is obtained in which sub-ray diffraction patterns are mixed.

[0045] The electron diffraction pattern originating from the first crystalline region clearly shows distinct spots derived from the crystallinity. It is recognized. Furthermore, the spot has orientation with respect to the thickness direction of the film.

[0046] On the other hand, the second crystalline portion consists of crystals present in the film that are oriented disorderly in all directions. This is the part. Therefore, the diameter of the electron beam used in electron diffraction (probe diameter), that is, the diameter of the observed Depending on the area of ​​the region, different images can be observed as follows.

[0047] Under conditions where the electron beam diameter (probe diameter) is sufficiently large (for example, 25 nmΦ or larger), Electron diffraction (selected field electron diffraction (SAED: Selected)) of 50 nmΦ or larger (Also known as Area Electron Diffraction) In the image, ring-shaped parts A turn is observed. Furthermore, the ring-shaped pattern has a luminance distribution in the radial direction. There is a connection. Limited-field electron diffraction is a type of electron diffraction that narrows the irradiation area to a very small area. This involves irradiating it with a parallel electron beam.

[0048] On the other hand, under conditions where the electron beam diameter (probe diameter) is sufficiently small (for example, 0.3 nm or larger) Furthermore, electron diffraction (nanobeam electron diffraction, NBED) of 10 nmΦ or less or 5 nm or less: In images of Nano Beam Electron Diffraction (also known as Nano Beam Electron Diffraction), control In the limited-field electron diffraction pattern, the ring-shaped pattern was observed in the circumferential direction (θ direction) and Multiple spots distributed in the area (also known as) are observed. That is, the limited-field electron diffraction pattern The ring-shaped pattern observed in the above is formed by an aggregate of the spots. It can be confirmed that it is present. Nanobeam electron diffraction is a type of focused electron diffraction. This method involves focusing an electron beam and irradiating the sample with it.

[0049] A metal oxide film according to one aspect of the present invention exhibits, in the limited field electron diffraction pattern of a cross-section, the first A first spot originating from the crystalline part and a ring-shaped pattern originating from the second crystalline part are mixed together. The diffraction pattern is confirmed. Furthermore, the metal oxide film shows a nanobeam electron diffraction pattern in its cross-section. In the circle, the first spot originates from the first crystal part, and the second spot originates from the second crystal part, and the circumference A diffraction pattern is observed in which multiple second spots, scattered along the direction, are mixed together.

[0050] Furthermore, in the limited-field electron diffraction pattern of the metal oxide film, a first spot and a ring These are located in the radial direction and overlap. Also, in the nanobeam electron diffraction pattern, Spot 1 and spot 2 are located at the same point in the radial direction.

[0051] Furthermore, the first spot originating from the first crystal portion originates from a crystal plane perpendicular to the c-axis of the crystal. This is a diffraction spot. When the crystal structure has twofold symmetry in the direction perpendicular to the c-axis, the first Two spots are observed symmetrically with respect to the center of the electron diffraction pattern. In addition to this first spot, the turn also has other spots originating from crystal planes perpendicular to the c-axis. In addition, diffraction spots originating from crystal planes other than those perpendicular to the c-axis may also be observed. .

[0052] Furthermore, when the ring and the first spot overlap in the radial direction, the multiple components that make up the ring The second numbered spot is on a crystal plane perpendicular to the c-axis of the crystal portion, which is oriented in a different direction. It can be understood that these are diffraction spots originating from the region.

[0053] Furthermore, in the limited-field electron diffraction pattern of the metal oxide film, two rings of different diameters are observed. A ring-like pattern (referred to as the first ring and the second ring from the inside) may be observed. At this time, the first spot originating from the first crystal portion is located inside the ring (first ring It is located in overlapping position with the second ring. Also, at the position overlapping with the second ring, there is a crystal originating from the first crystal part. Other spots may also be observed.

[0054] Here, when the proportion of the first crystalline portion having orientation in the metal oxide film is high Therefore, the resulting electron diffraction pattern will be dominated by a more anisotropic pattern. For example, In the limited-field electron diffraction pattern, the brightness of the first spot originating from the first crystal region is compared to As a result, the brightness of the first and second rings becomes relatively lower. Also, at this time, on the outside A different spot (third) originating from the first crystal portion is located in a position that overlaps with the second ring. A spot may also be observed. Here, the third spot and the second ring are radially moving. Since they overlap in the same direction, it can be inferred that they originate from diffraction from the same crystal plane.

[0055] Here, a second spot originating from a second crystalline region in the nanobeam electron diffraction pattern. The brightness (diffraction intensity) is smaller than the brightness of the first spot caused by the first crystal portion described above. This difference in brightness increases as the proportion of the first crystalline portion in the metal oxide film increases, and gold It can also serve as an indicator for assessing the crystallinity of the oxide film. For example, the brightness of the first spot is equal to that of the second spot. The brightness of the light is greater than 1x and less than or equal to 10x, preferably greater than 1x and less than 9x. More preferably, less than or equal to 1x, more preferably greater than 8x or less, and even more preferably 1.5x to 6x It is preferable that it is less than 2 times and more than 4 times.

[0056] A metal oxide film according to one aspect of the present invention is indium, M(where M is Al, Ga, Y, or S n) and an oxide film containing zinc. Such an oxide film has a layered structure along the c-axis. It has the characteristic of adopting a crystalline structure. Furthermore, such oxide films possess semiconductor properties. It has the following characteristics.

[0057] A metal oxide film according to one aspect of the present invention is applied to a semiconductor in which the channel of a transistor is formed. It is possible.

[0058] A metal oxide film containing a mixture of a first crystalline region with orientation and a second crystalline region without orientation. Transistors to which this technology is applied are metal oxides composed only of a second crystalline portion that does not have orientation. Compared to transistors with film coatings, it can achieve higher stability of electrical characteristics and a smaller channel length. It has features such as being easy to make into thin strips.

[0059] In the following section, one aspect of the present invention will be described with more specific examples.

[0060] [Metal oxides] A metal oxide film according to one aspect of the present invention comprises indium (In) and M (where M is Al, Ga, Y). It has (or Sn) and zinc (Zn). In particular, M is preferably gallium (Ga). It's nice.

[0061] When a metal oxide film contains In, for example, its carrier mobility (electron mobility) increases. Furthermore, if the metal oxide film has Ga, for example, the energy gap (Eg) of the metal oxide film The amount increases. Note that Ga is an element with a high bonding energy with oxygen, and the bond with oxygen The energy is higher than In. Also, when the metal oxide film has Zn, crystallization of the metal oxide film is likely to occur.

[0062] In addition, as the metal oxide film of one aspect of the present invention, it is preferable to have a crystal structure showing a single phase, particularly a homologous phase. For example, the metal oxide film has a composition of In M 1+x M 1-x O3(ZnO ) y (x is a number satisfying 0 < x < 0.5, and y represents the vicinity of 1.) By increasing the content ratio of In to M, the carrier mobility (electron mobility) of the metal oxide film can be increased .

[0063] In particular, the metal oxide film of one aspect of the present invention is In 1+x M 1-x O3(ZnO) y (x is a number satisfying 0 < x < 0.5, and y represents the vicinity of 1.) Among them, it is preferable to have a composition in the vicinity of In:M:Zn = 1. 33:0.67:1 (approximately In:M:Zn = 4:2:3). The metal oxide film having such a composition can have both high carrier mobility and high film stability .

[0064] In addition, the composition of the metal oxide film is not limited to this, and any composition that can have a layered crystal structure is acceptable. <00​​​​​​​​​​Preferably, Ga is 1.5 or more and 2.5 or less (1.5 ≤ Ga ≤ 2.5), and Zn is 2 or more and 4 or less (2 ≤ Zn ≤ 4).

[0066] [Formation of Metal Oxide Film] Hereinafter, samples on which three metal oxide films with different conditions were formed were prepared. First, the preparation methods of samples 1 to 4 will be described.

[0067] [Sample 1] Sample 1 is a sample on which a metal oxide film having indium, gallium, and zinc with a thickness of about 100 nm is formed on a glass substrate. The metal oxide film of Sample 1 was formed by heating the substrate to 130 °C and introducing argon gas with a flow rate of 180 sccm and oxygen gas with a flow rate of 20 sccm into the chamber of a sputtering ring device, setting the pressure to 0.6 Pa, and applying 2.5 kw of alternating current power to a metal oxide target having indium, gallium , and zinc (In:Ga:Zn = 4:2:4.1 [atomic ratio ). The above gas flow rate ratio may be described as an oxygen flow rate ratio based on the ratio of the oxygen flow rate to the total gas flow rate. At this time, the oxygen flow rate ratio under the preparation conditions of Sample 1 is 10%.

[0068] [Sample 2] Sample 2 is a sample on which a metal oxide film with a thickness of about 100 nm is formed on a glass substrate. The metal oxide film of Sample 2 was formed by heating the substrate to 170 °C and under the same conditions as Sample 1 except for the substrate temperature. The oxygen flow rate ratio under the preparation conditions of Sample 2 is 10%.

[0069] [Sample 3] Sample 3 is a sample on which a metal oxide film with a thickness of about 100 nm is formed on a glass substrate. ​​​​The metal oxide film of sample 3 was prepared by heating the substrate to 170°C and applying argon gas at a flow rate of 140 sccm. Then, oxygen gas at a flow rate of 60 sccm is introduced into the chamber of the sputtering apparatus, and the substrate Sample 3 was prepared under the same conditions as Sample 1, except for temperature and gas flow rate ratio. The flow rate ratio is 30%.

[0070] [Sample 4] Sample 4 is a sample in which a metal oxide film with a thickness of approximately 100 nm has been deposited on a glass substrate. The metal oxide film of material 4 was prepared without heating the substrate, using argon gas at a flow rate of 20 sccm and a flow rate of 10 Sccm oxygen gas is introduced into the sputtering apparatus chamber, and the pressure is set to 0.4 Pa. A metal oxide target having indium, gallium, and zinc (In:Ga: It was formed by applying 0.2 kW of alternating current to Zn (Zn=1:1:1 [atomic ratio]). The oxygen flow rate ratio under the preparation conditions for sample 4 was 33%.

[0071] [X-ray diffraction measurement] Figures 1(A), (B), and (C) show the results of XRD measurements performed on samples 1 through 3. This will be shown. Here, we will demonstrate the powder method (also known as the θ-2θ method), which is a type of out-of-plane method. The measurement was performed using ). The θ-2θ method involves changing the incident angle of the X-rays and the X-ray source. This method involves setting the angle of the detector, which is positioned facing the direction of the incident light, to the same angle as the incident light angle to measure the X-ray diffraction intensity. Furthermore, X-rays are incident from an angle of approximately 0.40° from the film surface, and the angle of the detector is changed to measure the X-rays. GIXRD (Grazio) is a type of out-of-plane method used to measure linear diffraction intensity. ng-Incidence XRD method (thin film method or Seemann-Bohlin method) Also known as ). ) may be used. In each figure in Figure 1, the horizontal axis is the angle 2θ, and the vertical axis is the diffraction strength. Degrees are shown in arbitrary units.

[0072] As shown in each figure in Figure 1, in all samples, the diffraction intensity peak is around 2θ = 31°. A peak intensity was confirmed. Furthermore, the peak intensities were highest for sample 3, followed by sample 2, and then sample 1.

[0073] The diffraction angle at which the diffraction intensity peak was observed (around 2θ = 31°) was for single crystal InGaZnO4. This coincides with the diffraction angle of the (009) plane in the structural model. Therefore, this peak is observed Therefore, in all samples, the c-axis is oriented in the direction of film thickness (hereinafter referred to as orientation). It can be confirmed that it contains a crystalline portion having (also called the first crystalline portion). From the comparison of strengths, the proportion of oriented crystalline regions was highest in sample 3, followed by sample 2, and then sample 1. It becomes clear that...

[0074] From these results, it can be seen that the higher the substrate temperature during film deposition and the larger the oxygen flow rate ratio, the more the orientation changes. A tendency was observed for the proportion of crystalline parts to increase.

[0075] [Cross-sectional observation] Figures 2(A) to (C) show the results of a transmission electron microscope (TE) scan of sample 1 to sample 3, respectively. M: Transmission Electron Microscopy image.

[0076] In samples 2 and 3, crystalline regions are observed where atoms are arranged in layers in the direction of film thickness. Sample 3 appears to have a higher proportion of regions oriented in the film thickness direction compared to Sample 2. On the other hand, in sample 1, although there are regions where atoms are arranged periodically, they are oriented in the direction of film thickness. The proportion of the crystalline portion is not as high as in samples 2 and 3.

[0077] [Electron diffraction] Next, the results of electron beam diffraction measurements for Samples 1 to 4 will be described. In the electron beam diffraction measurement, an electron beam diffraction pattern was obtained when the electron beam was incident perpendicularly to the cross-section of the sample. Also, the electron beam was measured with the beam diameter changed from 1 nm to 100 nm. The thickness of the sample was set to about 50 nm.

[0078] Hereafter, the electron beam diffraction patterns for each sample are shown. The electron beam diffraction patterns shown here are image data with the contrast adjusted so that the diffraction pattern becomes clear for clarity. Also, in the luminance analysis of the diffraction patterns shown hereafter, the unadjusted image data is used instead of the image data with the contrast adjusted as shown in the figure.

[0079] Here, the thickness of the sample used for electron beam diffraction will be described. In electron beam diffraction, not only the diameter of the incident electron beam but also the thicker the sample, the more information in the depth direction appears in the electron beam diffraction pattern. Therefore, not only by reducing the diameter of the electron beam (probe diameter), but also by thinning the sample, information on a more local area can be obtained. On the other hand, when the sample is too thin, for example, when the thickness is 5 nm or less, only information on an extremely fine area can be obtained. Therefore, if there are extremely fine crystals in that area, the obtained electron beam diffraction pattern may be the same pattern as that of a single crystal. When not aiming to analyze an extremely fine area, the thickness of the sample is preferably, for example, 10 nm or more and 100 nm or less, typically 10 nm or more and 50 nm or less. nm or more and 50 nm or less.

[0080] 〔Sample ①〕 The electron beam diffraction patterns of Sample ① are shown in FIGS. 3(A) and (B). FIGS. 3(A) and (B) are those ​​​​​​These are the electron diffraction patterns when the beam diameter is 100 nm and 1 nm, respectively. Figure 3(A In (B), the brightest spot in the center is due to the incident electron beam. This is the center of the electron diffraction pattern (also called the direct spot).

[0081] In Figure 3(A), two ring-shaped diffraction patterns with different radii can be observed. So, we'll call the rings with smaller diameters the first ring and the second ring. In comparison, it can be seen that the first ring has higher brightness. Also, the first ring overlaps with the other ring. Two spots (the first spot) indicated by arrows can be identified at the location.

[0082] The radial distance from the center of the first ring and the two first spots is given by the single crystal InG The radial distance from the center of the diffraction spot of the (009) plane in the structural model of aZnO4. It almost coincides with the separation.

[0083] The ring-shaped diffraction pattern observed suggests that within the metal oxide film, there are particles in all directions. Crystallized portion that is oriented (hereinafter also referred to as the non-oriented crystallized portion or the second crystallized portion) It can be confirmed that it exists.

[0084] Furthermore, the two first spots are arranged symmetrically with respect to the center point of the electron diffraction pattern. Since the brightness is similar, the crystalline portion originating from this first spot has twofold symmetry. It is inferred that this is the case. Also, as mentioned above, the two first spots are on the crystal plane perpendicular to the c-axis. Because it is a diffraction spot, a straight line (shown as a dashed line) connects the two first spots and the center. The direction of the straight line coincides with the orientation of the c-axis of the crystal portion. In Figure 3(A), the vertical direction is the direction of the film thickness. Because of this orientation, there are crystalline regions in the metal oxide film where the c-axis is oriented in the direction of film thickness. It becomes clear that...

[0085] Next, in Figure 3(B), the position of the first ring seen in Figure 3(A) is divided circumferentially. Multiple spots (second spots) can be seen. Furthermore, two first spots This can also be confirmed.

[0086] As shown in Figure 3(B), when the diameter of the incident electron beam is made extremely small, a circular shape is formed. Multiple second spots are observed distributed in the area, indicating that the metal oxide film is extremely minute and It can be seen that multiple crystalline regions with plane orientations in all directions are mixed together. The first ring seen in Figure 3(A) becomes visible as the observation area expands, revealing these fine crystals. It can be understood that this is the result of multiple diffraction spots from the same region being connected and the brightness being averaged out. .

[0087] Thus, the metal oxide film of sample 1 consists of oriented crystalline portions and non-oriented crystalline portions. It can be confirmed that the film contains a mixture of crystalline and non-crystalline parts. Furthermore, the first part from the oriented crystalline part The brightness of the first spot is higher than the brightness of the second spot, indicating the presence of crystalline parts in the film. Of these, a high proportion of oriented crystalline portions can be observed.

[0088] [Samples 2 and 3] Figures 4(A) and (B) show the electron diffraction patterns of sample 2, and Figures 4(C) and (D) show the electron diffraction patterns of sample 3. The electron diffraction patterns are shown separately. Figures 4(A) and (C) show the beam diameter at 100n. The values ​​are set to m, and Figures 4(B) and (D) show the results with a beam diameter of 1 nm, respectively. .

[0089] As shown in Figures 4(A) and (C), samples 2 and 3 show clearer distribution than sample 1. Two first spots originating from directional crystalline regions can be observed. The brightness increases in the order of sample 3, sample 2, and sample 1, indicating the relative abundance of oriented crystalline regions. However, this suggests that the order of importance is as follows.

[0090] Furthermore, as shown in Figures 4(A) and (C), in sample 2 and sample 3, the second ring overlaps. Two darker spots (a third spot) than the first spot can be observed at that location. As shown in Figure 3(A), in sample 1, this third spot is indistinguishable from the second ring. The brightness is high. The two third spots are rotated 90 degrees relative to the first spot. It is located at [location]. This third spot is a diffraction spot originating from a plane other than the crystal plane perpendicular to the c-axis. It is a pot.

[0091] Furthermore, in Figure 4(C), the area enclosed by the dashed line rotates 30 degrees relative to the first spot. High-luminosity areas were also observed at the rotated position and at the position rotated 60 degrees. As shown above, sample 3 exhibits orientation such that diffraction spots other than the first spot are clearly observed. It can be confirmed that the film has a high proportion of crystalline regions, meaning it is a highly crystalline film.

[0092] As shown in Figures 4(B) and (D), under conditions where the beam diameter is extremely small, the first phosphorus It can be seen that a second spot was observed at the location where the previous spot was observed. Also, sample 2 and In sample 3, a third spot, which was not observed in sample 1, was also confirmed.

[0093] [Sample 4] Figure 5 shows the electron diffraction pattern measured for sample 4 under conditions where the beam diameter was 100 nm. It indicates n.

[0094] In sample 4, although the first ring is visible, the first ring that was observed in samples 1 to 3 is absent. No spots were observed. This suggests that in sample 4, multiple rings originated from the first ring. A crystal having crystalline parts, in which the proportion of oriented crystalline parts is oriented in other directions. This suggests that the proportion of the departments is equivalent to the proportion of the departments themselves.

[0095] [Regarding the brightness of spots in electron diffraction patterns] As described above, the difference between the brightness of the first ring and the brightness of the first spot has orientation. This is important information for estimating the proportion of crystalline material.

[0096] Figure 6(A) shows an enlarged view of Figure 4(C). Here, an ideal single crystal of In In the electron diffraction pattern of GaZnO4, the position overlaps with the first ring in the radial direction. In this case, the first spot is positioned at 30 degrees, 90 degrees, and 12 degrees around the center of the electron diffraction pattern. Diffraction spots are not observed at positions rotated by 0 degrees each (the area enclosed by the dashed line in Figure 6(A)). It is known that it cannot be measured. In other words, the brightness that appears in this region is due to the metal oxide film. , electrons diffracted from crystalline regions other than the oriented crystalline regions, or from crystalline regions other than the crystalline regions in the film. It is thought to originate from scattered electrons from a region or substrate. Regarding random electrons, it is thought that they will be observed with equivalent intensity at positions where the radial path is equal, This can be ignored. Therefore, for example, the brightness of the first spot and this and 90 The difference in brightness at a rotated position is an important parameter for determining the proportion of oriented crystal regions. It becomes a meter.

[0097] Here, the difference between the brightness of the first spot and the brightness of the position rotated by a predetermined angle from it is: By normalizing with the brightness of the direct spot that appears at the center of the electron diffraction pattern, This allows for the determination of the values. Furthermore, it enables relative comparisons between each sample. .

[0098] Figure 7(A1) shows the electron diffraction pattern of sample 1 (the same as in Figure 3(A)). Furthermore, Figure 7(A2) shows the A-A' and A-A' lines passing through the first spot and direct spot in the figure. The normalized luminance profile for radial positions along each of the B-B' lines perpendicular to this. The file is shown. As shown in Figure 7(A2), two peaks are separated by the direct spot. A peak has been observed. Furthermore, there is a clear difference between the two peak brightness levels, A-A' and B-B'. It is being observed.

[0099] Figures 7(B1) and 7(B2) show the electron diffraction pattern and normality for sample 2, respectively. This is the luminance profile. Figures 7(C1) and 7(C2) are for sample 3, respectively. This shows the electron diffraction pattern and normalized brightness profile. Sample 2 is different from Sample 1. The difference between the peak brightness of the first spot and the peak brightness of the spot rotated 90 degrees from it is large. This is the case. Furthermore, it can be seen that this difference is larger in sample 3 than in sample 2.

[0100] Furthermore, in the B-B' direction of sample 2 and sample 3, at the position corresponding to the second ring, A peak that was not observed in sample 1 has been confirmed. Therefore, samples 2 and 3 are, It can be clearly seen that this sample has significantly higher crystallinity compared to sample 1.

[0101] Figures 7(D1) and 7(D2) show the electron diffraction pattern and normality of sample 4, respectively. This is the luminance profile. In sample 4, the profiles are almost identical in two directions. It can be seen that, in other words, sample 4 contains almost no oriented crystalline parts. It can be confirmed that the material contains multiple crystalline regions with crystal planes oriented in various directions.

[0102] Furthermore, when measured under conditions of a small beam diameter, the electron diffraction pattern shows a first ring. Because it appears as a discrete collection of bright spots, when comparing local brightness for a given location, the second In some cases, the brightness of ring 1 cannot be accurately determined. In such cases, use the dashed line shown in Figure 6(B). As shown, for a rectangular region with a specific width and whose longer side coincides with the radial direction, Using the brightness values ​​averaged along the width direction of the rectangle (the direction of the shorter side of the rectangle in Figure 6(B)), The luminance at a predetermined position may be calculated from the luminance profile in the radial direction.

[0103] Furthermore, when calculating the radial luminance profile, factors such as inelastic scattering from the sample may be present. Subtracting the luminance component as background allows for a more accurate comparison. This is possible. Here, the luminance component due to inelastic scattering is extremely broad in the radial direction. To obtain a suitable profile, the background brightness may be calculated using linear approximation. For example If so, draw a straight line along the tails on both sides of the target peak, and the point located on the lower brightness side of that line... The area can be subtracted as background.

[0104] Here, using the data with the background removed by the method described above, the first spot The brightness of the first spot and the brightness of the spot rotated 90 degrees from the first spot were calculated. Then, the brightness of the first spot was divided by the brightness of the spot rotated 90 degrees from the first spot. The value was calculated as relative luminance R.

[0105] For each of samples 1 to 4, the following measurements were taken under conditions where the beam diameter was 100 nm. Figure 8 shows the results of estimating the relative brightness R from the sub-ray diffraction pattern.

[0106] In sample 4, no difference in brightness was observed between the two positions, and the relative brightness R is 1. The luminance ratio increases in the order of Sample 1, Sample 2, and Sample 3.

[0107] For example, when a metal oxide film is used in the semiconductor layer where the transistor channel is formed: The relative luminance R is greater than 1 and less than or equal to 10, preferably greater than 1 and less than or equal to 9. Preferably, it is greater than 1x and 8x or less, more preferably 1.2x or more and 8x or less, and further Preferably 1.5 times or more and 6 times or less, more preferably 2 times or more and 6 times or less, even more preferably It is preferable to use a metal oxide film that is in the range of 2 times to 4 times. By using a specific oxide film as the semiconductor layer, high electrical stability and a low gate voltage range are achieved. This allows for a high field-effect mobility to be achieved simultaneously.

[0108] [Regarding fluctuations in orientation] Among the crystalline portions contained in the metal oxide film, the oriented crystalline portions have their orientations perfectly aligned. They are not identical; there is a fluctuation in the orientation direction. Below, we will discuss that fluctuation in the orientation direction. Let me explain.

[0109] The fluctuation in the orientation direction can be evaluated as follows: The electron diffraction pattern was measured at multiple locations, and for each image obtained, the electron diffraction pattern was analyzed. The inclination between the straight line passing through the center of the plane and the first spot and the thickness direction of the metal oxide film is measured. By doing so, it is possible to estimate the variation in the orientation direction of the crystal parts present in each region.

[0110] Here, under the condition that the electron beam diameter is 1 nm, the electron beam is directed parallel to the film surface direction. The electron diffraction pattern was acquired as a video image while scanning. The scan was performed at approximately 250 nm. It took 100 seconds to cover that distance.

[0111] Figure 9 shows some of the electron diffraction patterns of the captured video images for Sample 1, Sample 2, and Sample 3. Figure 9 shows nine electron diffraction patterns, and the intervals between them are shown. The interval is approximately 10 seconds.

[0112] In Figure 9, a dashed line shows the straight line passing through the first spot and the center of the electron diffraction pattern. As shown in Figure 9, there is variation in the orientation direction of the crystals depending on the region being observed. Confirmed.

[0113] Figure 10 shows the distribution of orientation directions estimated from each electron diffraction pattern shown in Figure 9. The horizontal axis represents the distance from the starting position of the image acquisition to the origin, and the vertical axis represents the measurement taken at each position. This is the angle of orientation at each position, with the average value of the orientation direction set to 0 degrees. Here, the clockwise direction is shown as positive. As shown in Figure 10, the orientation of each sample There was almost no difference in the magnitude of the directional variation, and all samples fell within a range of less than 10 degrees. I'm waiting.

[0114] The orientation direction of the crystal portion in the metal oxide film was measured under conditions where the electron beam diameter was increased. It can also be estimated by the circumferential spread of the spot in the electron diffraction pattern. This is possible. By increasing the beam diameter of the electron beam and widening the measurement range, it is possible to detect objects present within the measurement range. An electron diffraction pattern is obtained in which the information of the crystal region is averaged. The directional spread increases as the variation in the orientation direction of the crystal portion increases. The circumferential distribution reflects the proportion of crystal parts oriented in a specific direction. .

[0115] For example, as shown in Figure 6(A), the first spot is not a perfect point (or circle) shape. It has a shape that is close to an ellipse, spreading out in the circumferential direction. The angle between the two lines connecting each of the two ends to the center point of the electron diffraction pattern is This represents the variation in the orientation direction of the crystal portion. When the edge of the first spot is unclear For example, using the brightest point of the first spot as a reference, the position at 1σ or 2σ is the edge. It can be done as a part. Also, in cases where the difference in brightness between the first ring and the first spot is small, The estimation is based on the brightness distribution obtained by subtracting the brightness of the first ring from the brightness of the first spot. This is good. However, with this method, depending on the measurement conditions of the electron diffraction pattern, higher brightness is better. When the spread of the spot becomes larger and is overestimated compared to the actual variation in orientation. There is.

[0116] For example, the central angles at both ends of the first spot centered on the center of the electron diffraction pattern are 0 A temperature between 0°C and 45°C, preferably between 0°C and 40°C, more preferably between 0°C and 35°C. More preferably, the temperature is between 0 and 30 degrees. The higher the orientation, the better the metal oxide film. The stability of its electrical properties is improved.

[0117] [Proportion of crystalline parts] The proportion of crystalline regions in a metal oxide film can be estimated by analyzing cross-sectional images. Cut.

[0118] This section explains the image analysis method. Image processing is performed on TEM images acquired at high resolution. Then, the 2D Fast Fourier Transform (FFT) ) Process and obtain an FFT image. From the obtained FFT image, retain the periodic range, A masking process is applied to remove everything else. Then, the masked FFT image is processed into a 2D inverse FFT. Rie Transform (IFFT: Inverse Fast Fourier Transform) The image is then processed and an FFT filtered image is obtained.

[0119] This allows us to obtain a real-space image in which only the crystalline portion is extracted. Here, the remaining image The proportion of the crystalline portion can be estimated from the area ratio. Also, the image processing used By subtracting the remaining area from the area of ​​the region (also called the area of ​​the original image), the crystal part The proportion of the remaining parts can be estimated.

[0120] Figures 11(A) and (B) show cross-sectional TEM observations of sample 3 and sample 1 before image processing, respectively. The image is shown, and Figures 11(C) and (D) show the images obtained after image processing, respectively. Image processing In the later image, the white areas in the metal oxide film correspond to the areas containing the crystals. I will comply.

[0121] From Figure 11(C), the area excluding the region containing the crystalline part in sample 3 is approximately 21.0%. Furthermore, as estimated from Figure 11(D), the oriented crystalline portion in sample 1 included The proportion of the area excluding the undeveloped region was approximately 39.8%.

[0122] The proportion of the metal oxide film excluding the crystalline portion, as estimated in this way, is 5% or more. If the percentage is less than %, the metal oxide film is an extremely crystalline film, and its electrical properties are stable. It is preferable because it is high. Also, the proportion of the portion excluding the crystalline part in the metal oxide film is 20% or more. Less than 00%, preferably 20% to 90%, more preferably 20% to 80%, More preferably, it is 20% to 60%, and even more preferably, 30% to 50%. In that case, the metal oxide film has an appropriate ratio of oriented crystalline parts and non-oriented crystalline parts. This allows for a mixture of these elements, enabling both stable electrical properties and high mobility.

[0123] Here, the portion excluding the crystalline part that can be clearly identified by the cross-sectional observation image or this image analysis, etc. This is referred to as the Lateral Growth Buffer Region (LGBR). It can also be referred to as L. GBR has dense and sparse areas, and the sparse areas grow laterally, separating from the dense areas. They appear to be bonded. In particular, LGBR has an irregular surface orientation and is extremely fine. This region contains multiple crystalline parts of varying sizes and thicknesses. The presence of these crystalline parts is due to the beam. Electron diffraction with a large diameter (probe diameter) (e.g., 25 nmΦ or larger, or 50 nmΦ or larger) In the pattern, no spots were observed, and the beam diameter (probe diameter) was extremely small. (For example, electron diffraction patterns of 0.3 nm or more and 10 nmΦ or less or 5 nm or less) It can only be understood that it is observed as a spot, and that the crystalline part is extremely fine. ru.

[0124] For observing high-resolution TEM images, spherical aberration correction is necessary. The (on Corrector) function can be used. High-resolution using spherical aberration correction function. High-resolution TEM images are specifically called Cs-corrected high-resolution TEM images. For example, using an atomic resolution analytical electron microscope such as the JEM-ARM200F manufactured by JEOL Ltd. This can be observed.

[0125] [Electrical Characteristics of Transistors 1] In the following, a transistor was fabricated using the metal oxides of Sample 1 and Sample 3 described above, and I will now explain the results of the electrical characteristics measurements.

[0126] The transistor structure used is the one shown in Figure 36, which is illustrated in Embodiment 2. Two types of samples, sample A1 and sample A2, were prepared using different semiconductor layer formation conditions.

[0127] [Transistor fabrication] First, a 10nm thick titanium film and a 100nm thick copper film are placed on a glass substrate, It was formed using a taring device. Subsequently, the conductive film was processed by photolithography. Ta.

[0128] Next, four insulating films were laminated onto the substrate and conductive film. The insulating films were formed using plasma chemical gas The film was formed continuously in a vacuum using a phase deposition (PECVD) apparatus. The insulating film was formed from bottom to top in thickness 50nm silicon nitride film, 300nm thick silicon nitride film, 50nm thick silicon nitride A silicon oxidizide film with a thickness of 50 nm was used, respectively.

[0129] Next, an oxide semiconductor film is formed on an insulating film, and the oxide semiconductor film is processed into an island shape. Then, a semiconductor layer was formed. The oxide semiconductor film 108 was an oxide semiconductor with a thickness of 40 nm. A membrane was formed.

[0130] In sample A1, the metal oxide film used for the oxide semiconductor film was prepared under the same conditions as in sample 1. That is, assuming a substrate temperature of 130°C, an argon gas flow rate of 180 sccm and a flow rate 20 sccm of oxygen gas is introduced into the sputtering apparatus chamber, and the pressure is set to 0.6 Let Pa be a metal oxide target having indium, gallium, and zinc (In:G By applying 2.5 kW of AC power to a:Zn=4:2:4.1 [atomic ratio], the shape Success. The oxygen flow rate ratio was 10%. The thickness was approximately 40 nm.

[0131] In sample A2, the metal oxide film used for the oxide semiconductor film was prepared under the same conditions as in sample 3. That is, assuming a substrate temperature of 170°C, an argon gas flow rate of 140 sccm and a flow rate 60 sccm of oxygen gas is introduced into the sputtering apparatus chamber, and the pressure is set to 0.6 Let Pa be a metal oxide target having indium, gallium, and zinc (In:G By applying 2.5 kW of AC power to a:Zn=4:2:4.1 [atomic ratio], the shape Success. The oxygen flow rate ratio was 30%. The thickness was approximately 40 nm.

[0132] Next, an insulating film was formed on the insulating film and oxide semiconductor layer. The insulating film had a thickness of 15 A 0 nm silicon oxidoxide film was formed using a PECVD apparatus.

[0133] Next, heat treatment was performed. This heat treatment involved 3 [units of gas] under a mixed gas atmosphere of nitrogen and oxygen. The treatment involved heat treatment at 50°C for 1 hour.

[0134] Next, an opening was formed in a desired region of the insulating film. The method for forming the opening was dryer The etching method was used.

[0135] Next, an oxide semiconductor film with a thickness of 100 nm is formed on the insulating film so as to cover the opening. A conductive film was formed by processing an oxide semiconductor film into an island shape. Furthermore, after the conductive film was formed, Then, an insulating film was formed by processing an insulating film that was in contact with the underside of the conductive film.

[0136] A 100 nm thick oxide semiconductor film was formed as the conductive film. The body film was constructed as a two-layer stacked structure. The deposition conditions for the first oxide semiconductor film were as follows: With the plate temperature set to 170°C, oxygen gas at a flow rate of 200 sccm is supplied to the sputtering apparatus. A gold containing indium, gallium, and zinc is introduced into a bar and the pressure is set to 0.6 Pa. A 2.5kW ion generator is used on a group oxide target (In:Ga:Zn = 4:2:4.1 [atomic ratio]). By applying AC power, the film thickness was formed to 10 nm. The second layer of oxide semiconductor The deposition conditions for the conductive film were a substrate temperature of 170°C and an argon flow rate of 180 sccm. Gas and oxygen gas at a flow rate of 20 sccm are introduced into the chamber of the sputtering apparatus. The pressure is set to 0.6 Pa, and the target is a metal oxide containing indium, gallium, and zinc. A 2.5kW AC power is applied to a galvanic system (In:Ga:Zn = 4:2:4.1 [atomic ratio]). This process resulted in a film thickness of 90 nm.

[0137] Next, plasma treatment was performed on the oxide semiconductor film, insulating film, and conductive film. For the surface treatment, a PECVD apparatus was used, with the substrate temperature set to 220°C, and argon gas and nitrogen gas were used. The procedure was performed under a gas mixture atmosphere.

[0138] Next, an oxide semiconductor film, an insulating film, and an insulating film were formed on the conductive film. The insulating film was: A silicon nitride film with a thickness of 100 nm and a silicon oxide nitride film with a thickness of 300 nm are subjected to PECVD. It was formed by layering using a device.

[0139] Next, a mask is formed on the formed insulating film, and an opening is formed in the insulating film using the mask. did.

[0140] Next, a conductive film is formed to fill the opening, and the conductive film is processed into an island shape. A conductive film was formed to serve as the source electrode and drain electrode. The conductive film had a thickness of 10 A titanium film of nm thickness and a copper film of 100 nm thickness are produced using a sputtering apparatus, respectively. It was formed.

[0141] Next, an insulating film and an insulating film were formed on the conductive film. The insulating film was 1.5 μm thick. An acrylic-based photosensitive resin was used.

[0142] In this way, two types of transistors were fabricated.

[0143] [Electrical characteristics of transistors] Next, the Id-Vg characteristics of the transistors of the prepared samples A1 and A2 were measured. .

[0144] Furthermore, the measurement conditions for the Id-Vg characteristics of the transistor are as follows: The voltage applied to the conductive film (hereinafter also called the gate voltage (Vg)), and the second gate The voltage applied to the conductive film that functions as an electrode (also called Vbg) is changed from -15V to +20V. The voltage was applied in 0.25V steps up to V. It was also applied to a conductive film that functioned as a source electrode. The voltage (hereinafter also called the source voltage (Vs)) is set to 0V (comm), and the drain electrode The voltage applied to the conductive film that functions as such (hereinafter also called the drain voltage (Vd)) is 0. The voltages were set to 1V and 20V.

[0145] Figures 12(A) and (B) show the Id-Vg characteristic results for sample A1 and sample A2, respectively. In Figure 12, the first vertical axis represents Id(A), and the second vertical axis represents the field effect mobility (μFE( cm 2 The horizontal axis represents Vg(V), and the horizontal axis represents Vg(V). Also, in Figure 12, the total The Id-Vg characteristic results for the five transistors are shown superimposed.

[0146] As shown in Figures 12(A) and (B), both sample A1 and sample A2 exhibit good electrical characteristics. This was confirmed. Furthermore, it was confirmed that sample A1 had a higher field-effect mobility compared to sample A2. This was confirmed. In particular, the tendency was observed in the low Vg range (for example, Vg is 10V or less). It is remarkable.

[0147] In other words, in one aspect of the present invention, oriented crystal portions and non-oriented crystal portions are mixed. A transistor that uses a metal oxide film in the semiconductor layer where the channel is formed has high field efficiency. It was confirmed that the fruit mobility was observed. In particular, a high field effect was observed under conditions of low gate voltage. High mobility and a high drain current were confirmed.

[0148] [Evaluation of oxygen permeability] Next, we will explain the results of the evaluation of the oxygen permeability of the metal oxide film.

[0149] Here, the following three samples (Sample Ref, Sample B1, and Sample B2) were prepared. Sample B1 is a sample containing the metal oxide film of Sample 1, and Sample B2 is the same as the above sample. This is a sample containing a metal oxide film of type 3.

[0150] [Sample Ref] Sample Ref forms a silicon oxidizride film on a glass substrate that releases oxygen upon heating. This is the sample.

[0151] First, a silicon oxide nitride film was deposited on a glass substrate. The silicon oxide nitride film was deposited using a deposition gas. A mixed gas of SiH4 at a flow rate of 160 sccm and N2O at a flow rate of 4000 sccm was used. Under the conditions of a pressure of 200 Pa, a power of 1500 W, and a substrate temperature of 220 °C, the plasma CVD method was used. The film was then deposited. The thickness of the silicon oxidizride film is approximately 400 nm.

[0152] Next, the material was heat-treated at 350°C for 1 hour under a nitrogen atmosphere.

[0153] Next, the indium tin oxide film containing silicon (ITSO film) is subjected to sputtering. Further film deposition was performed. The thickness of the ITSO film is approximately 5 nm.

[0154] Next, the silicon oxidoxide-nitride film was subjected to oxygenation treatment. The oxygenation conditions were as follows: Using an ashing device, the substrate temperature is set to 100°C, and oxygen gas is supplied at a flow rate of 300 sccm. It is introduced into the chamber, the pressure is set to 25.06 Pa, and a bias is applied to the substrate side. The ashing process is performed by supplying 4750W of RF power between the electrodes of parallel plates installed inside the ashing device. Ta.

[0155] Subsequently, the indium tin oxide film was removed by wet etching, and the sample Ref and did.

[0156] [Sample B1] Sample B1 was first prepared by depositing a silicon oxidizride film using the same method as for sample Ref, and then heat treatment... The process was carried out, and after forming the indium tin oxide film, it was removed.

[0157] Next, an IG layer approximately 5 nm thick was applied to the silicon oxidizide film using the same method as for sample 1 above. A ZO film was deposited and designated as sample B1.

[0158] [Sample B2] Sample B2 was first prepared by depositing a silicon oxidizride film using the same method as for sample Ref, and then heat treatment... The process was carried out, and after forming the indium tin oxide film, it was removed.

[0159] Next, an IG layer approximately 5 nm thick was applied to the silicon oxidizride film using the same method as for sample 3 described above. A ZO film was deposited and designated as sample B2.

[0160] [TDS measurement] The three prepared samples were analyzed using thermal desorption gas analysis (TDS). (Oral Spectroscopy) shows the mass-to-charge ratio (M / z) of oxygen molecules. The release amounts of 32) were compared.

[0161] Figures 13(A), (B), and (C) show the results for sample Ref, sample B1, and sample B2, respectively. The measurement results are shown. In each figure, the vertical axis represents the detection intensity, and the horizontal axis represents the substrate temperature.

[0162] As shown in Figure 13(A), in sample Ref, oxygen content is measured from approximately 100°C to approximately 350°C. It was confirmed that offspring were released. Furthermore, sample Ref showed a peak around 250°C. .

[0163] As shown in Figure 13(B), in sample B1, oxygen begins to be released at approximately 150°C, and at approximately 3 A peak was observed around 50°C, and it was confirmed that oxygen continues to be released even at higher temperatures. Here it is. In other words, the metal oxide film used in sample B1 is a film that is easily permeable to oxygen. ru.

[0164] On the other hand, as shown in Figure 13(C), sample B2 has an oxygen peak at around 200°C. Although an emission profile is observed, the amount of emission is extremely low compared to sample B1. This was confirmed.

[0165] From the above results, it can be seen that oriented crystal parts and non-oriented crystal parts are mixed together, and that oriented A metal oxide film with a low proportion of crystalline parts is a film that allows oxygen to easily permeate, in other words, an oxygen-permeable film. It was confirmed that the film is one that allows diffusion easily.

[0166] [Evaluation of oxygen diffusion] The following describes the results of an evaluation of the ease with which oxygen diffuses into metal oxide films.

[0167] Here, we prepared the following two samples (Sample C1 and Sample C2).

[0168] [Sample C1] First, a metal oxide film with a thickness of approximately 50 nm is placed on a glass substrate using the same method as for sample 1 described above. A thin film was formed.

[0169] Next, a silicon oxide-nitride film with a thickness of approximately 30 nm and a silicon oxide-nitride film with a thickness of approximately 100 nm are placed on the metal oxide film. A silicon oxide nitride film, a silicon oxide nitride film with a thickness of approximately 20 nm, is produced by plasma CVD. It was formed by laminating layers.

[0170] Subsequently, heat treatment was performed at 350°C for 1 hour under a nitrogen atmosphere.

[0171] Next, a 5 nm thick indium tin oxide film was deposited using the sputtering method.

[0172] Next, the silicon oxidoxide-nitride film was subjected to oxygenation treatment. The oxygenation conditions were as follows: Using an ashing device, the substrate temperature is set to 40°C, and oxygen gas is supplied at a flow rate of 150 sccm. 16 O ) and oxygen gas at a flow rate of 100 sccm ( 18 O) is introduced into the chamber, and the pressure is set to 15 The parallel flat panel installed in the ashing device is set to Pa so that a bias is applied to the substrate side. The experiment was conducted by supplying 4500W of RF power between the electrodes of the plate for 600 seconds. Note that oxygen gas ( 1 8 The reason for using O) is that oxygen ( 16 O) at the principal component level Because it is contained, the oxygen added during the oxygenation process is used to accurately measure the added oxygen. ru.

[0173] Next, a silicon nitride film with a thickness of approximately 100 nm was deposited using plasma CVD.

[0174] Subsequently, the sample C1 was subjected to heat treatment at 450°C for 1 hour under a nitrogen atmosphere.

[0175] [Sample C2] Sample C2 is a sample obtained by changing the film deposition conditions for the metal oxide film of sample C1. A metal oxide film with a thickness of approximately 50 nm was deposited using the same method as for sample 3 described above.

[0176] [SIMS analysis] For samples C1 and C2, SIMS (Secondary Ion Mass) was performed. Spectrometry analysis18 The concentration of O was measured. The results are shown in Figure 14. This shows the following: glass substrate (referred to as "glass"), metal oxide film (referred to as "IGZO"). The analysis results for the region containing the silicon oxidizride film (indicated as SiON) are shown. The results shown here are from the substrate side (SSDP (Substrate Side Dept This is the result of an analysis (also known as h Profile-SIMS).

[0177] Both sample C1 and sample C2 contain silicon oxide nitride film 18 O is diffusing, and metal Even in oxide films 18 We were able to confirm that oxygen was diffusing. We will compare sample C1 and sample C2. And, sample C2 reached a deeper position. 18 O diffusion can be confirmed. Sample C1 It has diffused to a depth of approximately 25 nm.

[0178] From the above results, it can be seen that oriented crystal parts and non-oriented crystal parts are mixed together, and that oriented A metal oxide film with a low proportion of crystalline parts is a film that allows oxygen to easily permeate, in other words, an oxygen-permeable film. It was confirmed that the film is one that allows diffusion easily.

[0179] [Regarding the concept of supplying oxygen to oxide semiconductor films] Next, based on the model diagrams and calculation results shown in Figures 15 to 22, oxygen in the metal oxide film The concept for supplying this will be explained below.

[0180] Here, as an example of a metal oxide film, we will discuss the excess oxygen (stoichiometric ratio) in an IGZO film. This section will explain the ease with which oxygen (more oxygen than is supplied) and oxygen deficiency can be transported.

[0181] Furthermore, in this embodiment, the atomic ratio of IG is In:Ga:Zn = 3:1:2. Structural optimization of a model in which one In-O plane of a ZO film has either one excess oxygen or one oxygen deficiency. Created using the Nudged Elastic Band (NEB) method to minimize the amount of The energy for each intermediate structure along the energy pathway was calculated.

[0182] Furthermore, the calculation is performed using a calculation program software called "Op" based on density functional theory (DFT). The "enMX" model was used. The parameters used in the calculation included the pseudo-atomic localization basis function. A function was used. The basis set is the STO (Slater Type Orb) polarization basis system. It is classified as ital. Functionals include GGA / PBE (Generalized-Gr adient-Approximation / Perdew-Burke-Ernzer The hof (of) was used. The cutoff energy was set to 200 Ry. The number of points k was set to 5 × 5 × 3.

[0183] Furthermore, in calculations regarding the ease of movement of excess oxygen, the atoms present in the computational model With a number of 85, the calculation of the ease of movement of oxygen deficiencies is performed within the calculation model. The number of atoms was set to 83.

[0184] Furthermore, the ease with which excess oxygen moves, or the ease with which oxygen deficiency moves, is related to the excess oxygen and E is the height of the energy barrier that oxygen deficiencies must overcome when they travel to each site. This was evaluated by calculating b. That is, the high energy barrier that must be overcome during movement. If the energy barrier height Eb is high, movement is difficult; if the energy barrier height Eb is low, movement is easy.

[0185] (Regarding the movement of excess oxygen) First, let's explain the movement of excess oxygen. The atomic ratio is In:Ga:Zn=3:1:2 A model in which one excess oxygen atom exists on the In-O plane of an IGZO film is shown in Figures 15 to 1. This is shown in 8.

[0186] [(1) The first transition of excess oxygen] Figure 15(A) is a model diagram of the IGZO film, and Figure 15(B) is shown in Figure 15(A). Figure 15(C) is a model diagram of an enlarged view of region a1, and is derived from the model diagram shown in Figure 15(B). This is a model diagram illustrating the transition of excess oxygen. Note that Figures 15(B) to 15(C) The transition to ) is defined as the first transition of excess oxygen. Furthermore, the first transition of excess oxygen is the excess oxygen This is a transition in which oxygen diffuses from the InO2 layer to the (Ga,Zn)O layer.

[0187] [(2) Second transition of excess oxygen] Figure 16(A) is a model diagram of the IGZO film, and Figure 16(B) is shown in Figure 16(A). Figure 16(C) is a model diagram of an enlarged view of region a2, and is derived from the model diagram shown in Figure 16(B). This is a model diagram illustrating the transition of excess oxygen. Note that Figures 16(B) to 16(C) The transition to ) is considered the second transition of excess oxygen. Furthermore, the second transition of excess oxygen is the excess oxygen This is a transition in which (Ga,Zn)O ions diffuse from the first (Ga,Zn)O layer to the second (Ga,Zn)O layer.

[0188] [(3) The third transition of excess oxygen] Figure 17(A) is a model diagram of the IGZO film, and Figure 17(B) is shown in Figure 17(A). Figure 17(C) is a model diagram of an enlarged view of region a3, and is derived from the model diagram shown in Figure 17(B). This is a model diagram illustrating the transition of excess oxygen. Note that Figures 17(B) to 17(C) The transition to ) is defined as the third transition of excess oxygen. Furthermore, the third transition of excess oxygen is when excess oxygen This is a transition that diffuses along the In layer.

[0189] [(4) The fourth transition of excess oxygen] Figure 18(A) is a model diagram of the IGZO film, and Figure 18(B) is shown in Figure 18(A). Figure 18(C) is a model diagram of an enlarged view of region a4, and Figure 18(C) is derived from the model diagram shown in Figure 18(B). This is a model diagram illustrating the transition of excess oxygen. Note that Figures 18(B) to 18(C) The transition to ) is considered the fourth transition of excess oxygen. Also, the fourth transition of excess oxygen is when excess oxygen This is a transition that diffuses across the In layer.

[0190] Note that the "1" in Figures 15(B)(C), 17(B)(C), and 18(B)(C) The oxygen atom labeled as such is called the first oxygen atom. Figures 15(B)(C), 17(B) (C), and the oxygen atom labeled "2" in Figure 18(B)(C) is the second oxygen atom It is called "3" in Figures 16(B)(C), 17(B)(C), and 18(B)(C). The oxygen atom labeled as such is called the third oxygen atom. See “4” in Figure 16(B)(C) and the label The oxygen atom shown is called the fourth oxygen atom.

[0191] Figure 19 shows the calculation results for the ease of movement of excess oxygen. Note that in Figure 19, as described above... We calculated the four transition modes, with the horizontal axis representing the path length of excess oxygen transport and the vertical axis representing the path length shown in Figure 15. The energy required for movement is relative to the energy of the state shown in Figure 18 (B). .

[0192] As shown in Figure 19, the maximum value of the energy barrier height Eb for the first transition of excess oxygen ( Eb max ) is 0.62 eV, which is the energy barrier height for the second transition of excess oxygen. Maximum value of Eb (Eb max ) is 0.29 eV, and is the energy of the third transition of excess oxygen. - Maximum value of barrier height Eb (Eb max ) is 0.53 eV, and is the fourth of the excess oxygen Maximum value of the transition energy barrier height Eb (Eb max The value is 2.38 eV. Therefore, the first to third transitions of excess oxygen require more energy than the fourth transition of excess oxygen. The maximum value of the height Eb of Giebaria (Eb max ) is low. Therefore, the first transition of excess oxygen The energy required for the third transition is less than the energy required for the fourth transition of excess oxygen. Smaller transitions to excess oxygen (first to third transitions) occur more frequently than transitions to excess oxygen (fourth transition). It can be said that it is easy to understand.

[0193] That is, the first oxygen shown in the models of Figures 15(B), 17(B), and 18(B) As shown in Figures 18(B) and 18(C), the atom is in a direction that pushes out the third oxygen atom, rather than in the direction shown in Figure 15. As shown in (B)(C) and Figure 17(B)(C), the second oxygen atom is moved in the direction that pushes it out. Easy to move.

[0194] Furthermore, the third oxygen atom shown in the model in Figure 16(B) is, as shown in Figure 16(C), the third oxygen atom It is easier for the oxygen atom to move in the direction that pushes out the indium atom. It can be said that it is easier to move along the layer of indium atoms than to move across the other layers. Furthermore, oxygen atoms tend to move from the InO2 layer (G) rather than overcoming the indium atom layer. Movement to the (Ga,Zn)O layer, and from the first (Ga,Zn)O layer to the second (Ga,Zn)O layer. It can be said that it is easy.

[0195] [Regarding the movement of oxygen deficiency] Next, we will explain the movement of oxygen vacancies. The atomic ratio is In:Ga:Zn=3:1:2 and Figures 20 and 2 show a model in which one oxygen vacancy exists on the In-O plane of an IGZO film. As shown in 1.

[0196] [(5) The first transition in oxygen deficiency] Figure 20(A) is a model diagram of the IGZO film, and Figure 20(B) is shown in Figure 20(A). Figure 20(C) is a model diagram of an enlarged view of region a5, and is derived from the model diagram shown in Figure 20(B). This is a model diagram illustrating the progression of oxygen deficiency. Note that Figures 20(B) to 20(C) The transition to ) is defined as the first transition of oxygen deficiency. Furthermore, the first transition of oxygen deficiency is defined as the transition of oxygen deficiency This is a transition that diffuses along the In layer.

[0197] [(6) Second transition of oxygen deficiency] Figure 21(A) is a model diagram of the IGZO film, and Figure 21(B) is shown in Figure 21(A). Figure 21(C) is a model diagram of an enlarged view of region a6, and Figure 21(C) is derived from the model diagram shown in Figure 21(B). This is a model diagram illustrating the progression of oxygen deficiency. Note that Figures 21(B) to 21(C) The transition to ) is defined as the second transition of oxygen deficiency. Furthermore, the second transition of oxygen deficiency is defined as the transition of oxygen deficiency This is a transition that diffuses across the In layer.

[0198] Note that the dotted circles in Figures 20(B)(C) and 21(B)(C) represent oxygen deficiency. Yes, they are.

[0199] Figure 22 shows the calculation results for the ease of movement of oxygen deficiencies. Note that in Figure 22, the above We calculated the two transition modes, with the horizontal axis representing the path length of oxygen deficiency movement and the vertical axis representing Figure 20 and The energy required for movement is relative to the energy of the state shown in Figure 21(B). .

[0200] As shown in Figure 22, the maximum value of the energy barrier height Eb for the first transition of oxygen deficiency ( Eb max ) is 1.81 eV, which is the energy barrier height for the second transition of oxygen deficiency. Maximum value of Eb (Eb max ) is 4.10 eV. In the first transition of oxygen deficiency, oxygen The maximum value of the energy barrier height Eb is greater than the second transition of the defect (Eb max ) is low. Therefore, the energy required for the first transition of oxygen deficiency is equal to the energy required for the second transition of oxygen deficiency. It is smaller than energy. In other words, the first transition of oxygen deficiency is smaller than the second transition of oxygen deficiency. It can be said that this is more likely to occur than migration.

[0201] Therefore, similar to the movement of excess oxygen explained earlier, oxygen deficiency also involves the indium atom layer. It can be said that it is easier to move along the layer of indium atoms than to move over them.

[0202] [Regarding the temperature dependence of the transition] Next, in order to compare the likelihood of the six transition forms mentioned above from another perspective, these The temperature dependence of the transition will be explained below.

[0203] The temperature dependence of these transitions is compared by the frequency of migration per unit time. Therefore, the migration frequency Z (times / second) at a certain temperature is the number of oxygen atoms in a chemically stable position. Using the frequency Zo (cycles / second), it can be expressed by the following formula.

[0204]

number

[0205] Note that in formula (1), Eb maxThe height of the energy barrier at each transition is Eb. The maximum value of is where k is the Boltzmann constant, T is the absolute temperature, and Zo is the vibration of the atom at its stable position. The dynamics are shown separately. Note that for a typical Debye frequency, Zo = 1.0 × 10⁻⁶ 13 (times Since ( / second), in this embodiment, Zo = 1.0 × 10 13 Calculate (times / second) It is used for this purpose.

[0206] The value of Z when T=300K (27℃) is as follows: (1) First transition of excess oxygen: Z = 3.9 × 10 at T = 300 K 2 (times / second) (2) Second transition of excess oxygen: Z = 1.2 × 10 at T = 300 K 8 (times / second) (3) Third transition of excess oxygen: Z = 1.2 × 10 at T = 300 K 4 (times / second) (4) The fourth transition of excess oxygen: Z = 1.0 × 10 at T = 300 K -27 (times / second) (5) First transition of oxygen deficiency: Z = 4.3 × 10 at T = 300 K -18 (times / second) (6) Second transition of oxygen deficiency: Z = 1.4 × 10 at T = 300 K -56 (times / second)

[0207] Furthermore, the value of Z when T=723K (450℃) is as follows: (1) First transition of excess oxygen: Z = 4.8 × 10 at T = 723 K 8 (times / second) (2) Second transition of excess oxygen: Z = 9.2 × 10 at T = 723 K 10 (times / second) (3) Third transition of excess oxygen: Z = 2.0 × 10 at T = 723 K 9 (times / second) (4) The fourth transition of excess oxygen: Z = 2.5 × 10 at T = 723 K -4 (times / second) (5) First transition of oxygen deficiency: Z = 2.5 (times / second) at T = 723K (6) Second transition of oxygen deficiency: Z = 2.5 × 10 at T = 723 K -16 (times / second)

[0208] As mentioned above, excess oxygen is indigenous at both T=300K and T=723K. It is easier to move along the indium atom layer than to move across the mu atom layer. Furthermore, oxygen deficiency also occurs at both T=300K and T=723K, indium It can be said that it is easier to move along the layer of indium atoms than to move across the layer of other atoms.

[0209] Furthermore, at T=300K, the movement of excess oxygen along the indium atom layer, InO2 Transfer of excess oxygen from the layer to the (Ga,Zn)O layer, and from the first (Ga,Zn)O layer to the second The transfer of excess oxygen into the (Ga,Zn)O layer is likely to occur, but other transition modes are less likely to occur. At T=723K, not only does the excess oxygen mentioned above move, but also along the layer of indium atoms. Oxygen deficiency is also likely to occur, but indium is involved in both excess oxygen and oxygen deficiency. It is difficult for particles to move across atomic layers.

[0210] In the above explanation, it is assumed that excess oxygen or oxygen deficiency crosses over the indium atom layer. I have explained the case in which this occurs, but regarding other metals besides indium contained in the oxide semiconductor film... The same applies even if they are present.

[0211] As described above, even in the case of excess oxygen and oxygen deficiency, the indium atoms can move across the layer. In other words, movement in the c-axis direction is difficult for excess oxygen and oxygen deficiency.

[0212] [Regarding the ease of oxygen diffusion in metal oxide films and methods for reducing impurities in the films] The above results indicate that the higher the proportion (density) of oriented crystalline regions, the greater the oxygen in the thickness direction. This indicates that diffusion is difficult, and that the lower the density, the easier it is for oxygen to diffuse in the thickness direction. The ease of oxygen diffusion in this metal oxide film can be considered as follows: can.

[0213] In other words, it contains a mixture of oriented crystalline regions and extremely fine crystalline regions that do not have orientation. In metal oxide films, the parts other than the crystalline portion that can be clearly observed in cross-sectional images (LGBR) are This can become a region where oxygen can easily diffuse, i.e., an oxygen diffusion pathway. Therefore, orientation Because oxygen is more easily supplied to the crystalline parts via LGBR, the amount of oxygen deficiency in the film is reduced. It is thought that this can be reduced.

[0214] For example, by providing an oxide film that readily releases oxygen in contact with a metal oxide film and then applying heat treatment... As a result, the oxygen released from the oxide film is directed in the thickness direction of the metal oxide film by LGBR. It diffuses into the crystalline region. Then, via LGBR, oxygen is supplied from the side to the oriented crystalline region. This can be supplied. As a result, the crystalline portion having orientation of the metal oxide film and the other regions This allows for sufficient oxygen distribution and effectively reduces oxygen deficiency within the membrane.

[0215] Here, if there are hydrogen atoms in the metal oxide film that are not bonded to metal atoms, then It is thought that oxygen atoms bond, forming OH groups and becoming fixed. Therefore, during film formation... By forming the film at low temperatures, hydrogen atoms are trapped in oxygen vacancies (Vo) within the metal oxide film. A certain amount of (for example, 1 × 10) of state (called VoH) 17 cm-3 (To a certain extent) By forming OH This suppresses the generation of [unclear]. Also, since VoH generates carriers in the metal oxide film, A certain amount of carriers is present in the metal acid. As a result, the carrier concentration is increased. A phosphate film can be formed. Furthermore, oxygen vacancies are simultaneously formed during film formation, but these oxygen vacancies... As mentioned above, this can be reduced by introducing oxygen via LGBR. By such a method, metal acids with relatively high carrier concentrations and sufficiently reduced oxygen deficiency are obtained. It can form a methyl phosphate film.

[0216] Furthermore, regions other than the oriented crystalline parts undergo extremely fine deposition without orientation. Because it constitutes a crystalline region, no clear grain boundaries can be observed in the metal oxide film. The crystalline portion is located between multiple oriented crystalline portions. These fine crystalline portions are formed during film formation. By growing laterally due to heat, it bonds with adjacent oriented crystalline regions. The minute crystalline regions also function as carrier-generating regions. This is how such a configuration A metal oxide film having this property significantly improves the field-effect mobility of a transistor when applied to it. It is thought that this can be increased.

[0217] Furthermore, after forming a metal oxide film and then depositing an oxide insulating film such as a silicon oxide film on top of it... It is preferable to perform plasma treatment in an oxygen atmosphere. This treatment allows the film to be processed in In addition to supplying oxygen, hydrogen concentration can be reduced. For example, during plasma processing. Furthermore, any fluorine remaining in the chamber may also be doped into the metal oxide film. Fluorine exists as a negatively charged fluorine atom, and a positively charged hydrogen atom It is bonded with the atom by Coulomb force, generating HF. During the plasma treatment, the HF undergoes metal oxidation. It is released outside the film, and as a result, the hydrogen concentration in the metal oxide film can be reduced. Furthermore, in plasma processing, oxygen atoms and hydrogen combine to form H2O, which is released outside the film. In some cases, this may occur.

[0218] Furthermore, a configuration in which a silicon oxide film (or silicon oxide nitride film) is laminated on a metal oxide film. Consider this: Halogen elements such as fluorine in a silicon oxide film combine with hydrogen in the film, generating electricity. Because it can exist as neutral HF, it does not affect the electrical properties of the metal oxide film. Furthermore, Si-F bonds may form, but these are also electrically neutral. It is thought that HF ​​in the membrane does not affect oxygen diffusion.

[0219] Through the mechanism described above, oxygen vacancies in the metal oxide film are reduced, and the gold in the film is also reduced. It is believed that reliability can be improved by reducing the amount of hydrogen that is not bonded to a group atom. It can be obtained. Also, if the carrier concentration of the metal oxide film is above a certain level, the electrical properties will be improved. It is thought that...

[0220] [Evaluation by ESR] The following describes electron spin resonance (ESR) This section describes the results of investigating defect levels in metal oxide films using ce).

[0221] Defect levels in metal oxide films can be evaluated by ESR. ESR refers to the reaction of a sample. This analytical technique generates a magnetic field in the space in which the sample is placed and irradiates the sample with microwaves. (Magnetic flux density) The (H0) and / or microwave frequency (v) are changed, and the sample absorbs the microwaves. The equation g = hv / μ is derived from the frequency (v) and magnetic flux density (H0) when the vibration is settled. B Using H0, the g value The following parameters are obtained. Note that h is Planck's constant, and μ B It is a Bohr magneton. Both are constants.

[0222] In the signal measured by ESR, the g value is around 1.93 (1.89 or higher). The spin density corresponding to the signal in the range of 96 or less is oxygen-deficient (V O Corresponds to the abundance of ) ru.

[0223] Below, we prepared and evaluated the following two samples (samples D1 and D2). ESR measurement was performed. This process was carried out a total of three times in the steps following the deposition of the metal oxide film.

[0224] [Sample preparation] First, a metal oxide film was deposited on a quartz substrate. For sample D1, the same method as for sample 1 was used. A metal oxide film with a thickness of approximately 40 nm was deposited using this method. For sample D2, the same method as for sample 2 was used. A metal oxide film with a thickness of approximately 40 nm was deposited according to the method.

[0225] The first ESR measurement was performed at this stage.

[0226] Next, a silicon oxide-nitride film with a thickness of approximately 30 nm and a silicon oxide-nitride film with a thickness of approximately 100 nm are placed on the metal oxide film. A silicon oxide nitride film, a silicon oxide nitride film with a thickness of approximately 20 nm, is produced by plasma CVD. It was formed by laminating layers.

[0227] At this stage, a second ESR measurement was performed.

[0228] Subsequently, heat treatment was performed at 350°C for 1 hour under a nitrogen atmosphere.

[0229] Next, an oxide semiconductor film with a thickness of 100 nm was formed. Therefore, a two-layer laminated structure was adopted. The deposition conditions for the first oxide semiconductor film were set to the substrate temperature. At 170°C, oxygen gas at a flow rate of 200 sccm is introduced into the sputtering apparatus chamber. A metal oxide containing indium, gallium, and zinc is introduced and the pressure is set to 0.6 Pa. A 2.5kW AC current is applied to the target (In:Ga:Zn=4:2:4.1 [atomic ratio]). By applying force, the film thickness was formed to 10 nm. The second oxide semiconductor film The film deposition conditions were as follows: substrate temperature 170°C, argon gas flow rate 180 sccm, Oxygen gas at a flow rate of 20 sccm is introduced into the chamber of the sputtering apparatus, and the pressure is set to 0 The target is a metal oxide containing indium, gallium, and zinc, with a pressure of 0.6 Pa. Applying 2.5 kW of AC power to a mixture with a ratio of Ga:Zn = 4:2:4.1 (atomic ratio). Then, it was formed to have a film thickness of 90 nm.

[0230] Next, a silicon nitride film with a thickness of approximately 100 nm was deposited using plasma CVD.

[0231] Subsequently, heat treatment was performed at 250°C for 1 hour under a nitrogen atmosphere.

[0232] Next, the silicon nitride film and the two oxide semiconductor films directly beneath it are wet-etched. Further removal was performed.

[0233] At this stage, a third ESR measurement was performed.

[0234] [ESR measurement results] Figure 23 shows the spin density results for signals where the g value appears around 1.9. In the diagram, the results of the first, second, and third measurements are shown from left to right.

[0235] In all samples, the first measurement result, taken immediately after the metal oxide film was deposited, The spin density was below the detection limit. Also, twice immediately after deposition of the silicon oxidnitride film. In the eye measurements, the spin density increased. This is due to the metal acid during the deposition of the silicon oxidizide film. It is presumed that the damage to the oxide film is a result of increased oxygen deficiency in the metal oxide film. On the other hand, the deposition of the oxide semiconductor film and subsequent heat treatment bring the spin density back below the detection limit. This is because the deposition of an oxide semiconductor film and the subsequent heat treatment result in the formation of a metal This suggests that oxygen deficiencies in the oxide are reduced.

[0236] Furthermore, comparing sample D1 and sample D2, the spin density immediately after deposition of the silicon oxidizride film was A tendency for sample D1 to be higher than sample D2 was observed. However, even in sample D1, The oxygen vacancy is sufficiently reduced by the subsequent deposition and heat treatment of the oxide semiconductor film. You can see that.

[0237] [Evaluation by CPM] The following describes the constant photocurrent measurement method (CPM: Constant Photocurrent). Defect levels in the metal oxide film were evaluated using the following method.

[0238] CPM measurement is performed by applying a voltage between two electrodes placed on the sample and maintaining a constant photocurrent value. The amount of light irradiated onto the sample surface between the terminals is adjusted, and the absorption coefficient is derived from the amount of irradiated light. This is done at each wavelength. In CPM measurement, when there is a defect in the sample, the defect The absorption coefficient increases at energies (calculated from wavelength) corresponding to the existing energy levels. By multiplying the increase in the yield coefficient by a constant, the deep defect level density (hereinafter referred to as dDOS) of the sample can be calculated. (Also noted) can be derived.

[0239] From the absorption coefficient curve obtained by CPM measurement, the ar-backed tapering at the base of the band was found. By removing the absorption coefficient component called the "rule," the absorption coefficient due to the defect level can be expressed by the following formula. It can be calculated from here. Note that α(E) represents the absorption coefficient at each energy, α u This represents the absorption coefficient due to the arbuck tail.

[0240]

number

[0241] [Sample preparation] In the following section, we prepared and evaluated the following two samples (Sample E1 and Sample E2).

[0242] First, a metal oxide film was deposited on a glass substrate. In sample E1, the same method as in sample 1 was used. A metal oxide film with a thickness of approximately 100 nm was deposited using the method described above. Sample E2 was treated similarly to sample 2. A metal oxide film with a thickness of approximately 100 nm was deposited using this method.

[0243] Next, a silicon oxide-nitride film with a thickness of approximately 30 nm and a silicon oxide-nitride film with a thickness of approximately 100 nm are placed on the metal oxide film. A silicon oxide nitride film, a silicon oxide nitride film with a thickness of approximately 20 nm, is produced by plasma CVD. It was formed by laminating layers.

[0244] Subsequently, heat treatment was performed at 350°C for 1 hour under a nitrogen atmosphere.

[0245] Next, an oxide semiconductor film with a thickness of 100 nm was formed. Therefore, a two-layer laminated structure was adopted. The deposition conditions for the first oxide semiconductor film were set to the substrate temperature. At 170°C, oxygen gas at a flow rate of 200 sccm is introduced into the sputtering apparatus chamber. A metal oxide containing indium, gallium, and zinc is introduced and the pressure is set to 0.6 Pa. A 2.5kW AC current is applied to the target (In:Ga:Zn=4:2:4.1 [atomic ratio]). By applying force, the film thickness was formed to 10 nm. The second oxide semiconductor film The film deposition conditions were as follows: substrate temperature 170°C, argon gas flow rate 180 sccm, Oxygen gas at a flow rate of 20 sccm is introduced into the chamber of the sputtering apparatus, and the pressure is set to 0 The target is a metal oxide containing indium, gallium, and zinc, with a pressure of 0.6 Pa. Applying 2.5 kW of AC power to a mixture with a ratio of Ga:Zn = 4:2:4.1 (atomic ratio). Then, it was formed to have a film thickness of 90 nm.

[0246] Subsequently, the material was heat-treated at 350°C for 1 hour under a mixed gas atmosphere of nitrogen and oxygen.

[0247] Subsequently, the oxide semiconductor film was removed by etching using a wet etching method.

[0248] Next, a silicon oxide-nitride film was deposited. The silicon oxide-nitride film was deposited using a flow rate as the deposition gas. Using a mixed gas of 160 sccm of SiH4 and N2O at a flow rate of 4000 sccm, at a pressure of 2 The film was deposited by plasma CVD under the conditions of 00 Pa, 1500 W power, and a substrate temperature of 220°C. The thickness of the silicon oxidnitride film is approximately 400 nm.

[0249] Next, openings were formed in the silicon oxidnitride film using photolithography.

[0250] Next, a Ti film with a thickness of approximately 50 nm and an Al film with a thickness of approximately 400 nm were created using the sputtering method. A laminated film of Ti with a thickness of approximately 100 nm was formed. Subsequently, the laminated film was photolithographed. The electrodes were formed by processing using the Graphics method.

[0251] Subsequently, heat treatment was performed at 250°C for 1 hour under a nitrogen atmosphere.

[0252] Samples E1 and E2 were obtained through the above process.

[0253] [CPM evaluation results] Figures 24(A) and (B) show the results of CPM measurements performed on sample E1 and sample E2, respectively. The results are shown. The horizontal axis represents light energy, and the vertical axis represents the absorption coefficient. Also, the thick lines shown in each figure are The absorption coefficient curves for each sample are shown, with dotted lines indicating tangents and thin lines indicating optically measured absorption coefficients. This indicates.

[0254] The estimated arbach tail value for sample E1 from Figure 24(A) is 68.63 meV. Yes, the absorption coefficient obtained by subtracting the absorption coefficient caused by the bucktail from the absorption coefficient curve, in other words, The absorption coefficient value due to the defect is 1.36 × 10 -3 cm -1 On the other hand, Figure 24 The arbach tail value of sample E2 estimated from (B) was 68.70 meV, The absorption coefficient due to depression is 1.21 × 10⁻⁶. -3 cm -1 That was the case.

[0255] Based on these results, the metal oxide film of sample 1 and the metal oxide film of sample 2 exhibit clear defect levels. It was found that no difference was observed.

[0256] [Evaluation of defect levels using transistor characteristics] Defect levels in metal oxides are the electrical properties of transistors using metal oxide films as semiconductor layers. It can also be estimated from the properties. Below, we evaluate the density of the interface states of a transistor, and its In addition to the density of interface levels, the number of electrons trapped in interface levels N trap When considering this Next, we will explain how to predict subthreshold leakage current.

[0257] Number of electrons trapped in the interface level: N trap For example, the drain current of a transistor. -Measurement of gate voltage (Id-Vg) and drain current-gate voltage (Id-Vg) characteristics It can be evaluated by comparing it with the calculated value.

[0258] Figure 25 shows the calculations for source voltage Vs=0V and drain voltage Vd=0.1V. The ideal Id-Vg characteristic obtained and the measured Id-Vg characteristic in the transistor, This shows that, among the measurement results of the transistor, the drain current Id is easy to measure in 1×1 0 -13 Only values ​​greater than or equal to A were plotted.

[0259] Compared to the ideal Id-Vg characteristics calculated, the measured Id-Vg characteristics are different at the gate voltage V The change in drain current Id with respect to g becomes gradual. This is because the energy at the lower end of the conduction band ( This is thought to be because electrons were trapped in shallow interface levels located near (denoted as Ec). Here, the Fermi distribution function is used to determine which levels are trapped in shallow interface levels (per unit area). (Number of electrons per unit energy) N trap By taking this into consideration, the interface levels can be more precisely determined. Density N it It is possible to estimate this.

[0260] First, using the schematic Id-Vg characteristics shown in Figure 26, the interface trap level is used to trap the material. Number of electrons N trap This section explains the evaluation method. The dashed line represents the trap obtained through calculation. It exhibits an ideal Id-Vg characteristic with no energy levels. Also, in the dashed line, the drain current is Id1 The change in gate voltage Vg when it changes from Id2 is ΔV id Let's assume that. Also, the solid line is the actual The Id-Vg characteristics of the measured voltage are shown. In the solid line, the drain current changes from Id1 to Id2. The change in gate voltage Vg at that time is ΔV ex Let's assume that the drain currents are Id1 and Id2. The potentials at the interfaces of interest are φ it1 , φ it2 Let the change be Δφ it and do.

[0261] In Figure 26, the measured slope is smaller than the calculated slope, therefore ΔV ex ΔV id Rather It can be seen that it is large. At this time, ΔV ex and ΔV id The difference is that electrons are trapped in shallow interface levels. This represents the potential difference required to trigger the trapping. Therefore, it represents the change in charge due to the trapped electrons. Quantity ΔQ trap This can be expressed by the following equation (1).

[0262]

number

[0263] C tg This represents the combined capacitance of the insulator and semiconductor per unit area. Also, ΔQ trap is, tiger The number of electrons (per unit area, per unit energy) that have been added N trap Using equation (2) It can also be expressed as follows. Note that q is the elementary charge.

[0264]

number

[0265] Equation (3) can be obtained by solving equations (1) and (2) simultaneously.

[0266]

number

[0267] Next, consider Δφ in equation (3). it By taking the limit as zero, we can obtain equation (4). Cut.

[0268]

number

[0269] That is, using the ideal Id-Vg characteristics, the measured Id-Vg characteristics, and equation (4), the interface The number of trapped electrons N trap This can be estimated. Note that the drain current The relationship between the potentials at the interface was calculated using the device simulator described above. It can be calculated as follows.

[0270] Furthermore, the number of electrons N per unit area and unit energy trap and the density N of the interface levels it teeth The relationship is as shown in equation (5).

[0271]

number

[0272] Here, f(E) is the Fermi distribution function. The N obtained from equation (4) trap The formula ( 5) By fitting, N it This N is determined. it Devices that have been configured Transfer characteristics including Id < 0.1 pA can be obtained through calculations using a simulator. .

[0273] Next, we apply equation (4) to the measured Id-Vg characteristics shown in Figure 25, and N trap Extracted The results are shown in Figure 27 with circles. Here, the vertical axis of Figure 27 is the distance from the lower edge Ec of the semiconductor conduction band. This is the luminal energy Ef. Looking at the dashed line, the maximum value is located just below Ec. (Equation) (5) N it Assuming the tail distribution of equation (6), the dashed line in Figure 27 is very Good N trap It can be fitted, and the fitting parameter is the peak value N. t a = 1.67 × 10 13 cm -2 / eV, characteristic width W ta = 0.105 eV was obtained.

[0274]

number

[0275] Next, the obtained interface state fitting curve is used in calculations using a device simulator. Figure 28 shows the results of inversely calculating the Id-Vg characteristics by applying feedback. (A) The I obtained by calculation when the drain voltage Vd is 0.1V and 1.8V d-Vg characteristics and transistors with drain voltage Vd of 0.1V and 1.8V The measured Id-Vg characteristics in Figure 28(A) are shown. Figure 28(B) shows the drained characteristics in Figure 28(A). This is a logarithmic graph of the current Id.

[0276] The curve obtained by calculation and the plot of the measured values ​​are in close agreement, and the calculated values ​​and measured values ​​are in close agreement. This shows that it has high reproducibility. Therefore, it is a method for calculating shallow defect level density. Therefore, it can be seen that the above method is quite reasonable.

[0277] [Sample preparation] In the following section, four samples (samples F1 to F4) were prepared, and metal oxide films were created using the method described above. We evaluated the defect level density inside the material.

[0278] The preparation process for each sample is the same as for sample A, except for the film deposition conditions for the metal oxide film (oxide semiconductor film). The method for creating item 1 can be used as a substitute.

[0279] In sample F1, the metal oxide film used for the oxide semiconductor film was prepared under the same conditions as in sample 1. That is, assuming a substrate temperature of 130°C, an argon gas flow rate of 180 sccm and a flow rate 20 sccm of oxygen gas is introduced into the sputtering apparatus chamber, and the pressure is set to 0.6 Let Pa be a metal oxide target having indium, gallium, and zinc (In:G By applying 2.5 kW of AC power to a:Zn=4:2:4.1 [atomic ratio], the shape Success. The oxygen flow rate ratio was 10%. The thickness was approximately 40 nm.

[0280] In sample F2, the metal oxide film used for the oxide semiconductor film was prepared with a substrate temperature of 130°C. Then, argon gas at a flow rate of 140 sccm and oxygen gas at a flow rate of 60 sccm are sputtered together. The mixture is introduced into the chamber of the quenching device, the pressure is set to 0.6 Pa, and indium and gallium are added. Metal oxide target containing zinc (In:Ga:Zn = 4:2:4.1 [atomic ratio]) It was formed by applying 2.5 kW of AC power to ). The oxygen flow rate ratio was 10%. The thickness was set to approximately 40 nm.

[0281] In sample F3, the metal oxide film used for the oxide semiconductor film was prepared under the same conditions as in sample 2. That is, assuming a substrate temperature of 170°C, an argon gas flow rate of 180 sccm and a flow rate 20 sccm of oxygen gas is introduced into the sputtering apparatus chamber, and the pressure is set to 0.6 Let Pa be a metal oxide target having indium, gallium, and zinc (In:G By applying 2.5 kW of AC power to a:Zn=4:2:4.1 [atomic ratio], the shape Success. The oxygen flow rate ratio was 10%. The thickness was approximately 40 nm.

[0282] In sample F4, the metal oxide film used for the oxide semiconductor film was prepared under the same conditions as in sample 3. That is, assuming a substrate temperature of 170°C, an argon gas flow rate of 140 sccm and a flow rate 60 sccm of oxygen gas is introduced into the sputtering apparatus chamber, and the pressure is set to 0.6 Let Pa be a metal oxide target having indium, gallium, and zinc (In:G By applying 2.5 kW of AC power to a:Zn=4:2:4.1 [atomic ratio], the shape Success. The oxygen flow rate ratio was 30%. The thickness was approximately 40 nm.

[0283] The fabricated transistor had a channel length of approximately 6 μm and a channel width of approximately 50 μm.

[0284] [Defect level density] Figure 29(A) shows the electrical properties measured for samples F1 to F4 based on the method described above. The results of calculating the defect level density by comparing the actual values ​​with ideal calculated values ​​are shown.

[0285] Compared to samples F2 through F4, the defect level density in sample F1 is reduced to approximately half. It was confirmed that this was happening.

[0286] Based on the above results, by forming a metal oxide film under low temperature and low oxygen flow rate conditions, oxygen The improved permeability and increased amount of oxygen diffusing during the transistor fabrication process allow gold to penetrate more effectively. Defects such as oxygen vacancies in the oxide film and at the interface between the metal oxide film and the insulating film are reduced. It is presumed that this is the case.

[0287] [Electrical Characteristics of Transistors 2] Below, we will fabricate transistors capable of handling large currents and compare their on-currents. did.

[0288] The transistor structure used is the one shown in Figure 36, which is illustrated in Embodiment 2. Samples G1, G2, G3, and G4 were each formed under different semiconductor layer formation conditions. We prepared several types of samples.

[0289] [Transistor fabrication] The transistor of sample G1 was fabricated using the same method as sample F1 above. Similarly, the sample G2 is the same as sample F2, sample G3 is the same as sample F3, and sample G4 is the same as sample F4. It was created in accordance with the law.

[0290] The fabricated transistor has a channel length of 2 μm and a channel width of 20 It is μm.

[0291] [Transistor On-Current] Figure 29(B) shows the on-current of the transistor in each sample. Here, the gate voltage The drain current was measured when Vg was set to 10V and the drain voltage Vd was set to 5V.

[0292] As shown in Figure 29(B), sample G1 exhibits an extremely high on-current compared to the other samples. This was confirmed.

[0293] Based on the above results, by forming a metal oxide film under low temperature and low oxygen flow rate conditions, oxygen The improved permeability and increased amount of oxygen diffusing during the transistor fabrication process allow gold to penetrate more effectively. Defects such as oxygen deficiencies in the oxide film and at the interface between the metal oxide film and the insulating film are reduced. As a result of this effect, the defect level density is reduced, and the on-current of the transistor is significantly reduced. It was confirmed that it was rising.

[0294] Thus, transistors with improved on-current can charge and discharge their capacitance at high speed. It can be suitably used in switches. Typically, it is suitable for demultiplexer circuits, etc. It can be used for this purpose.

[0295] A demultiplexer circuit is a circuit that splits a single input signal into two or more signals for output. This is a demultiplexer circuit using such transistors, which is used in the signal lines of a display device. By placing it between the drive circuit and the signal line, when the signal line drive circuit is implemented in the form of an IC... This allows for a reduction in the number of terminals, enabling faster operation and a narrower bezel display device. It can be expressed.

[0296] [Electrical Characteristics of Transistors 3] In the following section, we fabricated miniature transistors and compared their electrical characteristics.

[0297] The transistor structure used is the one shown in Figure 36, which is illustrated in Embodiment 2. Three types of samples, H1, H2, and H3, each with different semiconductor layer formation conditions. I prepared the materials.

[0298] [Transistor fabrication] The preparation process for samples H1, H2, and H3 involves the deposition conditions for metal oxide films (oxide semiconductor films) and The method for preparing sample A1 described above can be used for the external preparation.

[0299] In sample H1, the metal oxide film used for the oxide semiconductor film was prepared under the same conditions as in sample 1. That is, assuming a substrate temperature of 130°C, an argon gas flow rate of 180 sccm and a flow rate 20 sccm of oxygen gas is introduced into the sputtering apparatus chamber, and the pressure is set to 0.6 Let Pa be a metal oxide target having indium, gallium, and zinc (In:G By applying 2.5 kW of AC power to a:Zn=4:2:4.1 [atomic ratio], the shape Success. The oxygen flow rate ratio was 10%. The thickness was approximately 40 nm.

[0300] In sample H2, the metal oxide film used for the oxide semiconductor film was prepared under the same conditions as in sample 3. That is, assuming a substrate temperature of 170°C, an argon gas flow rate of 140 sccm and a flow rate 60 sccm of oxygen gas is introduced into the sputtering apparatus chamber, and the pressure is set to 0.6 Let Pa be a metal oxide target having indium, gallium, and zinc (In:G By applying 2.5 kW of AC power to a:Zn=4:2:4.1 [atomic ratio], the shape Success. The oxygen flow rate ratio was 30%. The thickness was approximately 40 nm.

[0301] In sample H3, the metal oxide film used for the oxide semiconductor film was prepared with a substrate temperature of 170°C. Then, argon gas at a flow rate of 100 sccm and oxygen gas at a flow rate of 100 sccm are sputtered. It is introduced into the chamber of the ring device, the pressure is set to 0.6 Pa, and indium and gallium are added. A metal oxide target containing zinc (In:Ga:Zn=1:1:1.2 [atomic ratio]) This was formed by applying 2.5 kW of AC power to []). The oxygen flow rate ratio was 50%. Yes, it exists. The thickness was set to approximately 40 nm.

[0302] Two transistors of different sizes were fabricated in each sample. One had a channel length L. One transistor has a channel width of 2 μm and a channel width W of 3 μm, and the other has a channel length L of 3 μm. It is a transistor with a channel width W of 3 μm.

[0303] [Electrical characteristics of transistors] The measurement conditions for the Id-Vg characteristics of a transistor are as follows: the first gate electrode functions as... The voltage applied to the conductive film (hereinafter also called the gate voltage (Vg)), and the second gate electrode and The voltage applied to the conductive film that functions as a conductive film (also called Vbg) is set from -15V to +20V. The voltage was applied in 0.25V steps. Also, the voltage applied to the conductive film acting as the source electrode... The voltage (hereinafter also called the source voltage (Vs)) is set to 0V (comm), and the drain electrode is... The voltage applied to the functional conductive film (hereinafter also referred to as the drain voltage (Vd)) is set to 0.1V and The voltage was set to 10V.

[0304] Figures 30(A), (B), and (C) show that the channel length L of samples H1, H2, and H3 is 2 Figure 30(D) shows the Id-Vg characteristics of a transistor with a channel width W of 3 μm. In (E) and (F), the channel length L of samples H1, H2, and H3 is 3 μm, respectively. This shows the Id-Vg characteristics of a transistor with a width W of 3 μm. The number of measurements is 2 for sample H1 and H Samples 2 and H3 are both 3.

[0305] As shown in Figure 30, in all samples, the channel length is 2 μm, and the transistor is very small. Even with the presence of certain components, it was confirmed that good transistor characteristics were obtained.

[0306] Focusing on the field-effect mobility, it improves in the order of sample H3, sample H2, and sample H1. This was confirmed. When compared with a transistor with a channel length L of 2 μm, the field-effect mobility The maximum values ​​differed by approximately 2 times between sample H1 and sample H2, and by approximately 6 times between sample H1 and sample H3. .

[0307] Furthermore, focusing on the field-effect mobility profile, when the gate voltage is low (for example, 5V or less) (Bottom) It can be confirmed that the rise in the region is extremely steep in sample H1. .

[0308] Based on the above results, regarding the composition of the metal oxide film, increasing the proportion of indium will lead to electricity The field effect mobility is improved, and by depositing the film under low temperature and low oxygen flow conditions, the results are significantly better. It can be confirmed that the field effect mobility improves. For example, as shown in Figure 30(A), the field effect mobility Movement range: 30cm 2 Values ​​of / Vs or higher were obtained when the semiconductor layer was fabricated using low-temperature polysilicon. This value is comparable to that of a p-channel transistor, and was fabricated using oxide semiconductors. This is an extremely high value, unprecedented for a transistor.

[0309] [Method for forming metal oxide films] The following describes a method for forming a metal oxide film according to one aspect of the present invention.

[0310] A metal oxide film according to one aspect of the present invention is obtained by heating a substrate in an oxygen-containing atmosphere. The film can be formed by the puttering method.

[0311] The substrate temperature during film formation is 80°C to 150°C, preferably 100°C to 150°C. Typically, a temperature of 130°C is preferred. By increasing the temperature of the substrate, orientation is improved. It is possible to form more crystalline parts that possess properties.

[0312] Furthermore, the oxygen flow rate ratio (oxygen partial pressure) during film formation should be 1% or more and less than 33%, preferably 5% or less. Up to 30%, more preferably 5% to 20%, and even more preferably 5% to 15%. Below, it is preferable to set it to 10% as a typical example. By reducing the oxygen flow rate, the orientation can be controlled. This allows for the inclusion of more crystalline regions that are not present in the film.

[0313] Therefore, by setting the substrate temperature and oxygen flow rate during film formation within the above-mentioned range, orientation can be achieved. A metal oxide film can be obtained in which crystalline parts having orientation and crystalline parts without orientation are mixed together. It is possible. Furthermore, by optimizing the substrate temperature and oxygen flow rate within the above range, orientation can be achieved. This makes it possible to control the ratio of crystalline parts to non-oriented crystalline parts.

[0314] In-Ga-Z is an oxide target that can be used for depositing metal oxide films. Not limited to n-based oxides, for example, In-M-Zn oxides (where M is Al, Ga, Y, and The Sn) can be applied to this.

[0315] Furthermore, using a sputtering target containing a polycrystalline oxide having multiple crystal grains, When a metal oxide film containing crystalline parts, which are metal oxide films, is formed, a film without polycrystalline oxide is produced. Compared to using a puttering target, a crystalline metal oxide film can be obtained. water.

[0316] The following describes a consideration of the deposition mechanism of metal oxide films. The target for the polishing has multiple crystal grains, and these crystal grains have a layered structure. If the crystal grain has an interface that is easily cleaved, ions will be introduced into the sputtering target. By colliding them, the crystal grains cleave, and plate-shaped or pellet-shaped sputtering particles are formed. It may be obtained. The obtained flat or pellet-shaped sputtering particles on the substrate It is thought that a metal oxide film containing nanocrystals is formed by depositing it on the substrate. Heating promotes bonding or rearrangement of the nanocrystals on the substrate surface. This is thought to facilitate the formation of metal oxide films containing oriented crystalline regions. .

[0317] Note that here we have described the method of formation using the sputtering method, but in particular, sputtering The Taring method is preferable because it allows for easy control of crystallinity. In addition to the pulsed laser deposition (PLD) method, other methods include pulsed laser deposition (PECV) and plasma chemical vapor deposition (PECV). D) method, thermal CVD (Chemical Vapor Deposition) method, ALD Methods such as Atomic Layer Deposition (Atomic Layer Deposition) and vacuum deposition can also be used. An example of a thermal CVD method is MOCVD (Metal Organic Chemical). One example is the (al Vapor Deposition) method.

[0318] [Regarding the composition and structure of metal oxide films] A metal oxide film according to one aspect of the present invention can be applied to semiconductor devices such as transistors. In the following, we will focus on metal oxide films that have semiconductor properties (hereinafter referred to as oxide semiconductor films). I will explain about that.

[0319] [Regarding composition] First, let's explain the composition of the oxide semiconductor film.

[0320] Oxide semiconductor films, as described above, are made of indium (In) and M (where M is Al, Ga, It contains Y (or Sn), Zn (zinc), and .

[0321] Note that element M is aluminum, gallium, yttrium, or tin, but element M In addition to the above, other applicable elements include boron, silicon, titanium, iron, nickel, Germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium Tantalum, tungsten, magnesium, etc. may also be used as element M. You may combine multiple of the elements mentioned above.

[0322] Next, the original indium, element M and zinc contained in the oxide semiconductor film according to one aspect of the present invention The preferred range for the ratio of children will be explained using Figures 31(A), (B), and (C). Figures 31(A), (B), and (C) do not show the atomic ratio of oxygen. The terms of the atomic ratios of indium, element M, and zinc in the indium semiconductor film are given by [In Let ], [M], and [Zn] be the two elements.

[0323] In Figures 31(A), (B), and (C), the dashed line represents [In]:[M]:[Zn]=(1 The line where the atomic ratio is +α):(1-α):1 (-1≦α≦1), [In]:[M]: [Zn]=(1+α):(1-α):2 line, [In]:[M]:[ The line with the atomic ratio of Zn]=(1+α):(1-α):3, [In]:[M]:[Z The line where the atomic ratio of n]=(1+α):(1-α):4, and [In]:[M]:[ This represents the line where the atomic ratio of Zn is (1+α):(1-α):5.

[0324] Furthermore, the dashed line represents the atomic ratio of [In]:[M]:[Zn]=1:1:β (β≧0) The line where the atomic ratio is [In]:[M]:[Zn]=1:2:β, [In [In]:[M]:[Zn] = 1:3:β is the atomic ratio line, [In]:[M]:[Zn The line with an atomic ratio of ]=1:4:β, and the original [In]:[M]:[Zn]=2:1:β The line representing the atom ratio, and the line representing the atomic ratio of [In]:[M]:[Zn]=5:1:β. It represents "in".

[0325] Also, as shown in Figures 31(A), (B), and (C), [In]:[M]:[Zn]=0:2:1 Oxide semiconductors with atomic ratios or near-atomic ratios tend to adopt a spinel-type crystal structure.

[0326] Figures 31(A) and (B) show an oxide semiconductor film according to one embodiment of the present invention, containing indium An example of a preferred range for the atomic ratio of element M and zinc is shown.

[0327] As an example, Figure 32 shows InMZn, where [In]:[M]:[Zn]=1:1:1. Figure 32 shows the crystal structure of O4. Figure 32 also shows the InMZ crystal structure when viewed from a direction parallel to the b-axis. This is the crystal structure of nO4. Note that the layer containing M, Zn, and oxygen shown in Figure 32 (hereinafter referred to as (M, In the Zn layer, the metallic element represents element M or zinc. In this case, element M and sub Assume the proportion of lead is equal. Element M and zinc are substituted for each other, and their arrangement is irregular. ru.

[0328] InMZnO4 has a layered crystalline structure (also called a layered structure), as shown in Figure 32. A layer containing indium and oxygen (hereinafter referred to as the In layer) is divided into 1 part, and elements M, zinc, and The (M,Zn) layer containing oxygen is 2.

[0329] Furthermore, indium and element M are mutually substitutable. Therefore, the (M,Zn) layer The element M can be substituted with indium, and the layer can also be represented as an (In,M,Zn) layer. In that case, In It has a layered structure with one layer and two (In,M,Zn) layers.

[0330] In oxides with an atomic ratio of [In]:[M]:[Zn]=1:1:2, the In layer is 1: It adopts a layered structure in which the (M,Zn) layer is 3. That is, for [In] and [M], As the [Zn] content increases, the ratio of the (M,Zn) layer to the In layer when the oxide crystallizes... It increases.

[0331] However, in the oxide, the number of (M,Zn) layers is a non-integer for every one In layer. In this case, there are multiple types of layered structures where the number of (M,Zn) layers is an integer for every one In layer. There are cases where this occurs. For example, if [In]:[M]:[Zn]=1:1:1.5, then the In layer A layered structure in which there are 1 (M,Zn) layer and 2 (M,Zn) layers, and a layered structure in which there are 3 (M,Zn) layers. In some cases, a layered structure may be formed in which these materials are mixed together.

[0332] For example, when depositing an oxide semiconductor film using a sputtering apparatus, the number of atoms in the target A film with an atomic ratio that deviates from the ratio is formed. In particular, depending on the substrate temperature during film formation, the target... In some cases, the [Zn] content of the film may be smaller than that of the [Zn] content of the film.

[0333] Furthermore, multiple phases may coexist within an oxide semiconductor film (e.g., two-phase coexistence, three-phase coexistence). For example, the atomic ratio of [In]:[M]:[Zn]=0:2:1 is a neighboring atomic ratio. Therefore, two phases, a spinel-type crystal structure and a layered crystal structure, tend to coexist. Also, [In] In atomic ratios that are close to the atomic ratio that shows :[M]:[Zn]=1:0:0, the Bix Two phases, a bite-type crystal structure and a layered crystal structure, can easily coexist within an oxide semiconductor film. When these phases coexist, grain boundaries (also called grain boundaries) are formed between the different crystal structures. (u) may be formed.

[0334] On the other hand, when the content of indium and zinc in the oxide semiconductor film decreases, the carrier mobility Therefore, the atomic ratio that shows [In]:[M]:[Zn]=0:1:0, and In the vicinity of this value, the atomic ratio (for example, region C shown in Figure 31(C)) exhibits high insulating properties.

[0335] Therefore, an oxide semiconductor according to one aspect of the present invention has high carrier mobility and few grain boundaries. It is preferable to have an atomic ratio that tends to form a layered structure, as shown in region A of Figure 31(A). It's nice.

[0336] Furthermore, region B shown in Figure 31(B) is 4 from [In]:[M]:[Zn]=4:2:3 This shows 0.1 and its neighboring values. Neighboring values ​​include, for example, atomic ratios [In]:[M]. [Zn]=5:3:4 is included. Oxide semiconductor film having the atomic ratio shown in region B. This is an excellent oxide semiconductor film, particularly characterized by high crystallinity and high carrier mobility.

[0337] Furthermore, the conditions under which an oxide semiconductor film forms a layered structure are uniquely determined by the atomic ratio. No. The difficulty of forming a layered structure varies depending on the ratio of atoms. On the other hand, the same number of atoms Even with the same ratio, depending on the formation conditions, a layered structure may or may not be formed. Therefore, the region shown in the illustration is the region in which the oxide semiconductor film exhibits an atomic ratio having a layered structure. The boundaries between region A and region C are not strictly defined.

[0338] [Configuration using oxide semiconductor films in transistors] Next, we will explain a configuration that uses oxide semiconductor films in transistors.

[0339] Furthermore, by using oxide semiconductor films in transistors, for example, polycrystalline silicon can be used in... Compared to transistors used in the Nell region, it reduces carrier scattering at grain boundaries. This allows for the realization of transistors with high field-effect mobility. Furthermore, This makes it possible to create highly reliable transistors.

[0340] An oxide semiconductor film according to one aspect of the present invention comprises an oriented crystalline portion and a non-oriented crystalline portion. It is a film in which parts and are mixed. By using an oxide semiconductor film having such crystalline properties This makes it possible to realize transistors that achieve both high field-effect mobility and high reliability.

[0341] [Carrier density of oxide semiconductors] The carrier density of oxide semiconductor films is explained below.

[0342] Factors that affect the carrier density of oxide semiconductor films include oxygen in the oxide semiconductor film. Examples include defects (Vo) or impurities in oxide semiconductor films.

[0343] When the number of oxygen vacancies in an oxide semiconductor film increases, hydrogen atoms bond to these oxygen vacancies (this state is called Vo When (also referred to as H), the density of defect levels increases. Or, when the impurities in the oxide semiconductor film increase, the density of defect levels increases due to these impurities. Therefore, by controlling the density of defect levels in the oxide semiconductor film, the carrier density of the oxide semiconductor film can be controlled. When there are more, the density of defect levels increases due to these impurities. Therefore, by controlling the density of defect levels in the oxide semiconductor film, the carrier density of the oxide semiconductor film can be controlled.

[0344] Here, consider a transistor that uses an oxide semiconductor film in the channel region.

[0345] When aiming to suppress a negative shift in the threshold voltage of the transistor or to reduce the off-current of the transistor, it is preferable to lower the carrier density of the oxide semiconductor film. When lowering the carrier density of the oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be lowered and the density of defect levels may be lowered. In this specification and the like, a low impurity concentration and a low density of defect levels are referred to as high purity intrinsic or substantially high purity intrinsic. As the carrier density of a high purity intrinsic oxide semiconductor film, it is less than 8×10 cm preferably less than 1×10 cm 15 cm -3 and more preferably less than 1×10 ×10 11 cm -3 and it may be 1×10 10 cm -3 or more. -9 cm -3

[0346] On the other hand, when aiming to improve the on-current of the transistor or to improve the field-effect mobility of the transistor, it is preferable to increase the carrier density of the oxide semiconductor film. When increasing the carrier density of the oxide semiconductor film, the impurity concentration of the oxide semiconductor film may be slightly increased or the density of defect levels of the oxide semiconductor film may be slightly increased. When increasing the carrier density of the oxide semiconductor film, the impurity concentration of the oxide semiconductor film may be slightly increased or the density of defect levels of the oxide semiconductor film may be slightly increased. ​​Alternatively, it is preferable to make the band gap of the oxide semiconductor film smaller. For example, in the range where the on / off ratio of the Id-Vg characteristics of a transistor can be obtained, an oxide semiconductor film with a slightly higher impurity concentration or a slightly higher density of defect levels can be regarded as substantially intrinsic. Also, an oxide semiconductor film with a large electron affinity, which results in a smaller band gap and, as a consequence, an increased density of thermally excited electrons (carriers), can be regarded as substantially intrinsic. Further, when an oxide semiconductor film with a larger electron affinity is used, the threshold voltage of the transistor becomes lower. In the range where the on / off ratio of the Id-Vg characteristics of the transistor can be obtained, an oxide semiconductor film with a slightly higher impurity concentration or a slightly higher density of defect levels can be regarded as substantially intrinsic. Also, an oxide semiconductor film with a large electron affinity, which results in a smaller band gap and, as a consequence, an increased density of thermally excited electrons (carriers), can be regarded as substantially intrinsic. Further, when an oxide semiconductor film with a larger electron affinity is used, the threshold voltage of the transistor becomes lower. In the range where the on / off ratio of the Id-Vg characteristics of the transistor can be obtained, an oxide semiconductor film with a slightly higher impurity concentration or a slightly higher density of defect levels can be regarded as substantially intrinsic. Also, an oxide semiconductor film with a large electron affinity, which results in a smaller band gap and, as a consequence, an increased density of thermally excited electrons (carriers), can be regarded as substantially intrinsic. Further, when an oxide semiconductor film with a larger electron affinity is used, the threshold voltage of the transistor becomes lower.

[0347] The above-described oxide semiconductor film with an increased carrier density is slightly n-type. Therefore, the oxide semiconductor film with an increased carrier density may be referred to as "Slightly-n". Therefore, the oxide semiconductor film with an increased carrier density may be referred to as "Slightly-n". Therefore, the oxide semiconductor film with an increased carrier density may be referred to as "Slightly-n".

[0348] The carrier density of a substantially intrinsic oxide semiconductor film is preferably 1×10 5 cm -3 or more and less than 1×10 1 8 cm -3 more preferably 1×10 7 cm -3 or more and 1×10 17 cm -3 or less, more preferably 1×10 9 cm -3 or more and 5×10 16 cm -3 or less, even more preferably 1×10 10 cm -3 or more and 1×10 16 cm -3 or less, even more preferably 1×10 11 cm -3 or more and 1×1 or more and 1×10 15 cm -3 or less.

[0349] Furthermore, by using the substantially intrinsic oxide semiconductor film mentioned above, the reliability of the transistor is improved. Improvement may occur. Here, using Figure 33, an oxide semiconductor film is used in the channel region. This explains why the reliability of transistors improves. Figure 33 shows an oxide semiconductor film. This diagram illustrates the energy bands in transistors used in the channel region.

[0350] In Figure 33, GE represents the gate electrode, GI represents the gate insulating film, and OS represents the oxide semiconductor film. In this case, SD represents the source electrode or drain electrode, respectively. That is, Figure 33 shows the g A gate electrode, a gate insulating film, an oxide semiconductor film, and a source electrode in contact with the oxide semiconductor film. This is an example of the energy band of the drain electrode.

[0351] Furthermore, in Figure 33, a silicon oxide film is used as the gate insulating film, and an oxide semiconductor is used. The film uses In-Ga-Zn oxide. Furthermore, it can be formed within a silicon oxide film. The defect transition level (εf) is located approximately 3.1 eV away from the lower end of the conduction band of the gate insulating film. The oxide semiconductor film and silicon oxide film are formed when the gate voltage (Vg) is 30V. The Fermi level (Ef) of the silicon oxide film at the interface with the gate film is below the conduction band of the gate insulating film. It is assumed that the film is formed at a position approximately 3.6 eV away from the edge. The M level fluctuates depending on the gate voltage. For example, increasing the gate voltage can cause oxidation Fermi level (Ef) of the silicon oxide film at the interface between the semiconductor film and the silicon oxide film. The value will decrease. Also, the white circles in Figure 33 represent electrons (carriers), and X in Figure 33 represents silica oxide. This represents the defect level within the film.

[0352] As shown in Figure 33, when a gate voltage is applied, for example, when a carrier is thermally excited... Then, the carrier is trapped in the defect level (X in the diagram), and moves from positive ("+") to neutral. The charge state of the defect level changes to (0). That is, the Fermi level of the silicon oxide film. The value obtained by adding the energy of the thermal excitation described above to (Ef) is greater than the defect transition level (εf). In this case, the charge state of the defect levels in the silicon oxide film changes from positive to neutral, and the transient The threshold voltage of the station will fluctuate in the positive direction.

[0353] Furthermore, when oxide semiconductor films with different electron affinities are used, the gate insulating film and the oxide semiconductor film The depth at which the Fermi level is formed at the interface may differ. When a monocrystalline semiconductor film is used, near the interface between the gate insulating film and the oxide semiconductor film, the gate insulating film The lower end of the conduction band of the edge film becomes relatively higher. In this case, a defect level may form in the gate insulating film. Because the position (X in Figure 33) also becomes relatively high, the Fermi level of the gate insulating film and the oxide semiconductor The energy difference with the Fermi level of the body membrane increases. This reduces the amount of charge trapped in the gate insulating film. For example, the silicon oxide mentioned above. The change in the charge state of defect levels that can form in the film is reduced, and the gate bias heat (Gat e Bias Temperature (also known as GBT) Transition in stress This can reduce fluctuations in the threshold voltage of the sta.

[0354] Furthermore, the time required for charges trapped in defect levels of an oxide semiconductor film to disappear is long. Furthermore, it can behave as if it were a fixed charge. Therefore, oxidation with a high defect level density Transistors in which a channel region is formed in a monocrystalline semiconductor film may have unstable electrical properties. be.

[0355] Therefore, in order to stabilize the electrical characteristics of a transistor, the impurity concentration in the oxide semiconductor film must be reduced. Reducing the degree is effective. Also, to reduce the impurity concentration in the oxide semiconductor film It is preferable to also reduce the concentration of impurities in the adjacent membrane. Examples of impurities include hydrogen and nitrogen. These include alkali metals, alkaline earth metals, iron, nickel, silicon, etc.

[0356] Here, we will explain the effects of various impurities in oxide semiconductor films.

[0357] In oxide semiconductor films, if silicon or carbon, which are among the Group 14 elements, are present, acid Defect levels are formed in oxide semiconductor films. Therefore, in oxide semiconductor films, silico The concentration of silicon and carbon, and the concentration of silicon and carbon near the interface with the oxide semiconductor film (secondary ionic content) Secondary Ion Mass Spectrometer (SIMS) The concentration obtained by y) is 2 × 10 18 atoms / cm 3 The following is preferably 2 × 1 0 17 atoms / cm 3 The following applies:

[0358] Furthermore, if the oxide semiconductor film contains alkali metals or alkaline earth metals, defect levels They may form and generate carriers. Therefore, alkali metals or alkaline earth metals Transistors using oxide semiconductor films containing this group tend to exhibit normally-on characteristics. Therefore, the concentration of alkali metals or alkaline earth metals in the oxide semiconductor film is reduced. It is preferable that alkali gold in oxide semiconductor films obtained by SIMS The concentration of the genus or alkaline earth metal is 1 × 10⁻⁶. 18 atoms / cm 3 The following are preferred 2 x 10 16 atoms / cm 3 Do the following:

[0359] Furthermore, in oxide semiconductor films, when nitrogen is present, electrons, which act as carriers, are generated. The riac density increases, making it more likely to become n-type. As a result, the oxide semiconductor film containing nitrogen... Transistors used in semiconductors tend to exhibit normally-on characteristics. For example, oxide semiconductors. The nitrogen concentration in the membrane is 5 × 10⁻⁶ in SIMS. 19 atoms / cm 3 Less than, preferably is 5 x 10 18 atoms / cm 3 More preferably 1 × 10 18 atoms / cm 3 More preferably 5 × 10 17 atoms / cm 3 The following applies:

[0360] Furthermore, the hydrogen contained in the oxide semiconductor film reacts with the oxygen bonded to the metal atoms to form water. Therefore, an oxygen deficiency may form. When hydrogen enters this oxygen deficiency, the carrier Electrons may be generated. Also, some of the hydrogen combines with oxygen that combines with metal atoms. It can generate electrons, which are carriers. Therefore, an oxide semiconductor film containing hydrogen. Transistors using this material tend to exhibit normally-on characteristics. Therefore, in oxide semiconductor films... It is preferable that the hydrogen content in the oxide semiconductor film be reduced as much as possible. Specifically, Then, the hydrogen concentration obtained by SIMS is 1 × 10⁻⁶ 20 atoms / cm3 Less than, preferred ku is 1 x 10 19 atoms / cm 3 Less than 5x10 18 ate / c m 3 Less than 1 × 10 18 atoms / cm 3 Less than.

[0361] An oxide semiconductor film with sufficiently reduced impurities is used in the channel formation region of the transistor. This allows for the provision of stable electrical characteristics.

[0362] Furthermore, oxide semiconductor films have an energy gap of 2 eV or more, or 2.5 eV or more. It would be desirable to have it.

[0363] Furthermore, the thickness of the oxide semiconductor film is 3 nm or more and 200 nm or less, preferably 3 nm or more. The wavelength is 00 nm or less, and more preferably 3 nm to 60 nm.

[0364] Furthermore, if the oxide semiconductor film is In-M-Zn oxide, then the In-M-Zn oxide film is deposited. The atomic ratio of metal elements used for the sputtering target is In:M:Zn =1:1:0.5, In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, I n:M:Zn=2:1:1.5, In:M:Zn=2:1:2.3, In:M:Zn=2 :1:3, In:M:Zn=3:1:2, In:M:Zn=4:2:4.1, In:M: A Zn ratio of 5:1:7 is preferred.

[0365] This embodiment may be appropriately combined with other embodiments described herein, at least in part. They can be implemented in combination.

[0366] (Embodiment 2) In this embodiment, the transistor that can be used in a semiconductor device according to one aspect of the present invention is I will explain this in detail.

[0367] In this embodiment, the top-gate transistor is shown in Figures 34 to 4. I will explain using number 5.

[0368] [Transistor Configuration Example 1] Figure 34(A) is a top view of transistor 100, and Figure 34(B) is a top view of Figure 34(A). Figure 34(C) is a cross-sectional view between the dashed line X1-X2, and Figure 34(A) is a cross-sectional view between the dashed line Y1-Y This is a cross-sectional view between the two. Note that in Figure 34(A), for clarity, the structure of the insulating film 110 and other components is shown. Elements are omitted in the diagram. Note that in the top view of the transistor, the following diagrams... Even if some components are omitted from the illustration, as in Figure 34(A), there are cases where they are not shown. The direction of the dashed line X1-X2 is the channel length (L) direction, and the direction of the single dashed line Y1-Y2 is the channel width ( This is sometimes referred to as the W direction.

[0369] The transistor 100 shown in Figure 34(A),(B),(C) is connected to the insulating film 104 on the substrate 102. and an oxide semiconductor film 108 on the insulating film 104, and an insulating film 110 on the oxide semiconductor film 108 The conductive film 112 on the insulating film 110, the insulating film 104, the oxide semiconductor film 108, and the conductive The film 108 has an insulating film 116 on the film 112. The channel region 108i overlaps with the insulating film 116, and the source region 108s is in contact with the insulating film 116. It has a drain region 108d that is in contact with 116.

[0370] Furthermore, the insulating film 116 contains nitrogen or hydrogen. The insulating film 116 and the source region 108 When s and the drain region 108d come into contact, nitrogen or hydrogen in the insulating film 116 becomes s It is added to the source region 108s and the drain region 108d. In the rain region 108d, the carrier density increases with the addition of nitrogen or hydrogen.

[0371] Furthermore, transistor 100 has an insulating film 118 on insulating film 116 and insulating films 116, 11 A conductive material is electrically connected to the source region 108s through the opening 141a provided in 8. Through the film 120a and the openings 141b provided in the insulating films 116 and 118, the drain region It may also have a conductive film 120b that is electrically connected to region 108d.

[0372] In this specification, etc., insulating film 104 is referred to as the first insulating film, and insulating film 110 as the second insulating film. The edge film, insulating film 116 (referred to as the third insulating film), and insulating film 118 (referred to as the fourth insulating film) are respectively. In some cases, the conductive film 112 functions as a gate electrode, and the conductive film 120 a functions as a source electrode, and the conductive film 120b functions as a drain electrode. To possess.

[0373] Furthermore, the insulating film 110 also functions as a gate insulating film. It has an excess oxygen region. The insulating film 110 has an excess oxygen region, which means that the oxide semiconductor film 1 Excess oxygen can be supplied to the channel region 108i of 08. Therefore, Since the oxygen deficiency that may form in the Nell region 108i can be compensated for by excess oxygen, We can provide highly reliable semiconductor devices.

[0374] In order to supply excess oxygen to the oxide semiconductor film 108, Excess oxygen may be supplied to the insulating film 104 formed below 8. In this case, insulating film 10 The excess oxygen contained in 4 is located in the source region 108s of the oxide semiconductor film 108, and It can also be supplied to the rain region 108d. Source region 108s and drain region 108d When excess oxygen is supplied to the source region 108s and the drain region 108d, The price may increase.

[0375] On the other hand, the insulating film 110 formed on top of the oxide semiconductor film 108 has excess oxygen. By doing so, it becomes possible to selectively supply excess oxygen only to channel region 108i. Alternatively, channel region 108i, source region 108s, and drain region 10 After supplying excess oxygen to 8d, the source region 108s and drain region 108d are subjected to By selectively increasing the rear density, the resistance of the source region 108s and the drain region 108d is increased. It is possible to suppress the increase in resistance.

[0376] Furthermore, the source region 108s and drain region 108d of the oxide semiconductor film 108 are Each element preferably has an element that forms an oxygen vacancy or an element that bonds with the oxygen vacancy. i. Typical elements that form the oxygen vacancy, or elements that bond with the oxygen vacancy, are Examples include hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, chlorine, titanium, and noble gases. Also, representative examples of noble gas elements include helium, neon, argon, krypton, and Examples include xenon. The insulating film 116 contains one or more of the elements that form the oxygen vacancies. If this occurs, the material will diffuse from the insulating film 116 to the source region 108s and the drain region 108d. Alternatively, the element that forms the above oxygen vacancy is subjected to impurity addition treatment to the source region 10⁸s , and added to the drain region 108d.

[0377] When impurity elements are added to an oxide semiconductor film, the bonds between metal elements and oxygen in the oxide semiconductor film are formed. The bond is cleaved, and an oxygen vacancy is formed. Alternatively, an impurity element is added to the oxide semiconductor film. Then, the oxygen that was bonded to the metal element in the oxide semiconductor film combines with the impurity element, and the metal element Oxygen is removed from the film, forming an oxygen vacancy. As a result, in oxide semiconductor films, Carrier density increases, and conductivity improves.

[0378] Next, we will explain the details of the components of the semiconductor device shown in Figures 34(A), 34(B), and 34(C). .

[0379] 〔substrate〕 The substrate 102 is made of a material that has sufficient heat resistance to withstand the heat treatment during the manufacturing process. It is possible.

[0380] Specifically, alkali-free glass, soda-lime glass, alkali glass, crystal glass Materials such as quartz or sapphire can be used. Inorganic insulating films may also be used. Examples of such inorganic insulating films include silicon oxide films, silicon nitride films, and silicon oxide nitride. Examples include films, aluminum oxide films, and the like.

[0381] Furthermore, the alkali-free glass mentioned above has a thickness of, for example, 0.2 mm to 0.7 mm. This would be appropriate. Alternatively, the above thickness can be achieved by polishing alkali-free glass.

[0382] Furthermore, as alkali-free glass, the 6th generation (1500mm x 1850mm) and the 7th generation... (1870mm x 2200mm), 8th generation (2200mm x 2400mm), 9th generation Areas such as (2400mm x 2800mm), 10th generation (2950mm x 3400mm), etc. This allows for the use of large glass substrates, making it possible to manufacture large display devices. It is possible.

[0383] Furthermore, the substrate 102 can be a single-crystal semiconductor substrate made of silicon or silicon carbide, or a polycrystalline substrate. Semiconductor substrates, compound semiconductor substrates such as silicon germanium, SOI substrates, etc. may be used. .

[0384] Furthermore, inorganic materials such as metals may be used as the substrate 102. Examples include stainless steel or aluminum.

[0385] Furthermore, the substrate 102 may be made of an organic material such as resin, resin film, or plastic. The resin film may be polyester, polyolefin, polyamide (na Iron, aramid, etc.), polyimide, polycarbonate, polyurethane, acrylic resin, Epoxy resin, polyethylene terephthalate (PET), polyethylene naphthalate (P Examples include EN, polyethersulfone (PES), or resins containing siloxane bonds. It can be done.

[0386] Furthermore, a composite material combining inorganic and organic materials may be used as the substrate 102. The composite material is made by laminating a metal plate or a thin glass plate with a resin film. Combined materials, fibrous metal, particulate metal, fibrous glass, or particulate glass Materials dispersed in an oil film, or fibrous resins, or particulate resins dispersed in an inorganic material. Materials, etc., are examples.

[0387] Furthermore, the substrate 102 can support at least a film or layer formed above or below it. Any film will do, and it may be one or more of the following: insulating film, semiconductor film, or conductive film. stomach.

[0388] [First insulating film] The insulating film 104 can be deposited using sputtering, CVD, vapor deposition, or pulsed laser deposition. It can be formed using appropriate methods such as PLD, printing, and coating. Also, insulating film 104 For example, this involves forming an oxide insulating film or a nitride insulating film as a single layer or in multiple layers. This can be done. Furthermore, in order to improve the interface characteristics with the oxide semiconductor film 108, the insulating film 104 is In this case, it is preferable that at least the region in contact with the oxide semiconductor film 108 be formed of an oxide insulating film. Furthermore, an oxide insulating film that releases oxygen upon heating is used as the insulating film 104. Then, the heat treatment transfers the oxygen contained in the insulating film 104 to the oxide semiconductor film 108. It is possible.

[0389] The thickness of the insulating film 104 is 50 nm or more, or 100 nm to 3000 nm, This can be between 200 nm and 1000 nm. By increasing the thickness of the insulating film 104 This can increase the amount of oxygen released from the insulating film 104, and also allow the insulating film 104 and the oxide semiconductor to separate. Interface states at the interface with the conductive film 108, and channel regions 1 of the oxide semiconductor film 108 It is possible to reduce the oxygen deficiency contained in 08i.

[0390] Examples of dielectric film 104 include silicon oxide, silicon oxide nitride, silicon nitride oxide, and nitrile oxide. Silicon oxide, aluminum oxide, hafnium oxide, gallium oxide, or Ga-Zn oxide The following can be used, and it can be provided in a single layer or in a multilayer structure. In this embodiment, the insulating film As 104, a laminated structure of silicon nitride film and silicon oxidizide film is used. In addition, an insulating film 104 is used as a laminated structure, with a silicon nitride film on the lower layer and a silicon oxidative nitride film on the upper layer. By using a silicon film, oxygen can be efficiently introduced into the oxide semiconductor film 108. Cut.

[0391] [Oxide semiconductor film] As the oxide semiconductor film 108, the metal oxide film described in Embodiment 1 can be used. can.

[0392] Furthermore, when the oxide semiconductor film 108 is formed by the sputtering method, the film density can be increased. Therefore, it is suitable. When forming an oxide semiconductor film 108 by sputtering, The tarling gas can be a noble gas (typically argon), oxygen, or a mixture of noble gases and oxygen. Mixed gases are used as appropriate. Furthermore, high-purity sputtering gases are also necessary. For example, The oxygen and argon gases used as sputtering gases have a dew point of -60°C or lower, and are preferred. Alternatively, by using a gas purified to below -100°C, water can be added to the oxide semiconductor film 108. This can prevent, as much as possible, the inclusion of fractions and other elements.

[0393] Furthermore, when forming an oxide semiconductor film 108 by sputtering, a sputtering apparatus is used. The chamber in the chamber is designed to remove as much water and other impurities as possible from the oxide semiconductor film 108. To achieve a high vacuum (5 × 10⁻¹⁰), use an adsorption-type vacuum pump such as a cryopump. - 7 Pa to 1 × 10 -4 It is preferable to exhaust to approximately Pa. In particular, sputtering During standby of the device, gas molecules equivalent to H2O in the chamber (at m / z=18 phase) The partial pressure of the corresponding gas molecules is 1 × 10⁻⁶ -4 Pa or less, preferably 5 × 10 -5 Set to Pa or less. It is preferable.

[0394] [Second insulating film] The insulating film 110 functions as the gate insulating film of the transistor 100. 10 has the function of supplying oxygen to the oxide semiconductor film 108, particularly to the channel region 108i. For example, the insulating film 110 may be an oxide insulating film or a nitride insulating film, either as a single layer or in a multilayer configuration. It can be formed in this way. Furthermore, in order to improve the interfacial properties with the oxide semiconductor film 108 In the insulating film 110, the region in contact with the oxide semiconductor film 108 is at least an oxide insulating film. It is preferable to form it using a film. As the insulating film 110, for example, silicon oxide, nitrogen oxide Silicon oxide, silicon nitride, silicon nitride, etc., can be used.

[0395] Furthermore, the thickness of the insulating film 110 is 5 nm or more and 400 nm or less, or 5 nm or more and 300 nm. It can be less than or equal to m, or between 10 nm and 250 nm.

[0396] Furthermore, the insulating film 110 preferably has few defects, and typically, electron spin resonance (EMR) The signal observed in (ESR: Electron Spin Resonance) A smaller value is preferable. For example, the signal mentioned above is observed when the g value is 2.001. E' centers are one example. Note that E' centers occur in dangling bonds of silicone. This is due to the fact that the insulating film 110 has a spin density originating from the E' center of 3 × 10⁻¹⁰ 17 SPI ns / cm 3The following is preferably 5 × 10 16 spins / cm 3 The following is silicon oxide A film, or a silicon oxidizride film, can be used.

[0397] In addition, the insulating film 110 also contains signals caused by nitrogen dioxide (NO2) in addition to the signals mentioned above. Nulls may be observed. This signal is divided into three signals by the nuclear spin of N. The grain is cracked, and each g-value is between 2.037 and 2.039 (considered the first signal). , g value between 2.001 and 2.003 (considered a second signal), and g value of 1.96 Observed when the value is between 4 and 1.966 (considered the third signal).

[0398] For example, as an insulating film 110, the spin density due to nitrogen dioxide (NO2) is 1 × 10⁻⁶. 1 7 spins / cm 3 The above 1 x 10 18 spins / cm 3 If an insulating film less than 100% is used It is suitable.

[0399] Furthermore, nitrogen oxides (NO2) containing nitrogen dioxide (NO2) x ) creates energy levels in the insulating film 110 It is formed. The level is located within the energy gap of the oxide semiconductor film 108. Therefore, nitrogen oxides (NOx) diffuse to the interface between the insulating film 110 and the oxide semiconductor film 108. As a result, the level in question may trap electrons on the insulating film 110 side. Because the wrapped electrons remain near the interface between the insulating film 110 and the oxide semiconductor film 108, This shifts the threshold voltage of the transistor in the positive direction. Therefore, insulating film 11 As for 0, if a film with a low nitrogen oxide content is used, the threshold voltage of the transistor is This can reduce the need for shifting.

[0400] Nitrogen oxides (NO x Examples of insulating films with low emission of ) include silicon oxide nitride films. The silicon oxidnitride film can be analyzed by temperature-controlled desorption gas analysis (TDS:Th In ermal desorption spectroscopy, nitrogen oxides (NO x This is a membrane that releases more ammonia than the amount of ) released, and typically, it is a membrane that releases ammonia Output volume 1 × 10 18 molecules / cm 3 The above 5 x 10 19 molecules / cm 3 The following applies. The amount of ammonia released is when the heat treatment temperature in TDS is between 50°C and 650°C. This refers to the total amount in the range of 50°C to 550°C.

[0401] Nitrogen oxides (NO x ) reacts with ammonia and oxygen during heat treatment, therefore By using an insulating film that emits a large amount of monia, nitrogen oxides (NOx) can be released. x ) is reduced.

[0402] Furthermore, when the insulating film 110 was analyzed by SIMS, the nitrogen concentration in the film was 6 × 10⁻⁶. 20 ato ms / cm 3 The following is preferable:

[0403] Furthermore, as the insulating film 110, hafnium silicate (HfSiO x ), nitrogen is added Hafnium silicate (HfSi x O y N z ), Nitrogen-added hafnium aluminum (HfAl x O y N z), high-k materials such as hafnium oxide may also be used. By using this high-k material, gate leakage in transistors can be reduced.

[0404] [Third insulating film] The insulating film 116 contains nitrogen or hydrogen. Furthermore, the insulating film 116 contains fluorine. This may also be the case. Examples of the insulating film 116 include a nitride insulating film. Examples include silicon nitride, silicon oxide nitride, silicon oxide nitride, silicon fluoride nitride, It can be formed using silicon fluoride nitride or the like. Hydrogen concentration contained in insulating film 116 is 1 × 10 22 atoms / cm 3 It is preferable that the above is true. Also, the insulating film 116 is acid It is in contact with the source region 108s and the drain region 108d of the ionized semiconductor film 108. This refers to impurities in the source region 108s and drain region 108d that are in contact with the insulating film 116. As the (nitrogen or hydrogen) concentration increases, the source region 108s and the drain region 108d This can increase carrier density.

[0405] [Fourth insulating film] As the insulating film 118, an oxide insulating film can be used. In this case, a laminated film of an oxide insulating film and a nitride insulating film can be used. For example, silicon oxide, silicon nitride, silicon nitride oxide, aluminum oxide, Hafnium oxide, gallium oxide, or Ga-Zn oxide can be used.

[0406] Furthermore, the insulating film 118 functions as a barrier film against external elements such as hydrogen and water. It is preferable to do so.

[0407] The thickness of the insulating film 118 is 30 nm or more and 500 nm or less, or 100 nm or more and 400 nm. It can be less than or equal to m.

[0408] [Conductive film] The conductive films 112, 120a, and 120b were produced using sputtering, vacuum deposition, and pulsed deposition methods. It can be formed using methods such as laser deposition (PLD) and thermal CVD. Furthermore, conductive films... 112, 120a, and 120b are conductive metal films and have the function of reflecting visible light. A conductive film having the property of transmitting visible light may be used.

[0409] Examples of conductive metal films include aluminum, gold, platinum, silver, copper, chromium, and tantalum. Titanium, molybdenum, tungsten, nickel, iron, cobalt, palladium, or manganese Materials containing metal elements selected from the above can be used. Alternatively, the above metal elements can be used. Alloys containing these alloys may also be used.

[0410] Specifically, the conductive metal film mentioned above is a two-layer structure in which a copper film is laminated on a titanium film. Two-layer structure with a copper film laminated on a titanium nitride film, and two-layer structure with a copper film laminated on a tantalum nitride film. The structure uses a three-layer structure in which a copper film is laminated on a titanium film, and then another titanium film is formed on top of that. This is sufficient. In particular, by using a conductive film containing copper, the resistance can be lowered. Suitable. Also suitable as a conductive film containing copper elements, or an alloy film containing copper and manganese. The alloy film is suitable because it can be processed using a wet etching method. .

[0411] Furthermore, tantalum nitride films are preferably used as conductive films 112, 120a, and 120b. Yes, the tantalum nitride film is conductive and has a high barrier against copper or hydrogen. It possesses the property of being oxidative. Furthermore, tantalum nitride films release less hydrogen from themselves, so oxidation As a metal film in contact with the material semiconductor film 108, or as a metal film in the vicinity of the oxide semiconductor film 108, It can be used most preferably.

[0412] Furthermore, as the conductive film having the aforementioned conductivity, a conductive polymer or conductive polymer can be used. That's fine.

[0413] Furthermore, the conductive film having the function of reflecting visible light as described above may be gold, silver, copper, or paraben. Materials containing metallic elements selected from zinc can be used. In particular, conductive materials containing silver can be used. Using a film is preferable because it can increase the reflectivity in visible light.

[0414] Furthermore, the conductive films having the function of transmitting visible light as described above include indium, tin, zinc, Materials containing gallium or elements selected from silicon can be used. Specifically These include In oxide, Zn oxide, In-Sn oxide (also called ITO), and In-Sn-Si Examples include oxides (also called ITSO), In-Zn oxide, In-Ga-Zn oxide, etc. ru.

[0415] Furthermore, the conductive film having the function of transmitting visible light as described above is graphene or graph A film containing a phytomethic acid may also be used. Examples of films containing graphene include films containing graphene oxide. By forming a film containing graphene oxide and reducing the film containing graphene oxide, a film containing graphene is formed. It is possible to reduce it. Methods of reduction include applying heat and using reducing agents. It is possible.

[0416] Furthermore, the conductive films 112, 120a, and 120b can be formed by electroless plating. Materials that can be formed by this electroless plating method include, for example, Cu, Ni, Al, One or more of the following materials can be used: Au, Sn, Co, Ag, and Pd. This is possible. In particular, using Cu or Ag makes it possible to lower the resistance of the conductive film. Therefore, it is suitable.

[0417] Furthermore, when a conductive film is formed by electroless plating, the constituent elements of the conductive film may spread to the outside. To prevent diffusion, a diffusion-preventing film may be formed beneath the conductive film. A seed layer on which a conductive film can be grown may be formed between the film and the conductive film. The above-mentioned diffusion prevention film can be formed, for example, using a sputtering method. Furthermore, as the diffusion prevention film, for example, a tantalum nitride film or a titanium nitride film may be used. This can be done. Furthermore, the above seed layer can be formed by electroless plating. Furthermore, the seed layer may be a conductive film material that can be formed by electroless plating. The same materials as those used for the ingredients can be used.

[0418] Furthermore, an oxide semiconductor, such as In-Ga-Zn oxide, is used as the conductive film 112. This may be done. The oxide semiconductor is supplied with nitrogen or hydrogen from the insulating film 116, Carrier density increases. In other words, oxide semiconductors are oxide conductors (OC: Oxide It functions as a conductor. Therefore, the oxide semiconductor is used as the gate electrode. It can be used.

[0419] For example, the conductive film 112 may be a single-layer structure of an oxide conductor (OC) or a single-layer structure of a metal film. Examples include a laminated structure of an oxide conductor (OC) and a metal film.

[0420] Furthermore, the conductive film 112 may be a single-layer structure of a light-shielding metal film, or an oxide conductor. When using a laminated structure of OC and a light-shielding metal film, the conductive film 112 is formed below the conductive film 112. It is preferable because the channel region 108i can be shielded from light. Also, the conductive film 11 As for the second, lamination of an oxide semiconductor or oxide conductor (OC) and a light-shielding metal film. When using this structure, a metal film (for example, a metal film) is placed on an oxide semiconductor or oxide conductor (OC). By forming a tungsten film (or similar), the constituent elements in the metal film become oxide semiconductors. Alternatively, it diffuses to the oxide conductor (OC) side and reduces resistance, or damage during metal film deposition (for example) Resistance is reduced due to sputtering damage, etc., or an oxide semiconductor in the metal film. Alternatively, oxygen diffusion in oxide conductors (OCs) can create oxygen vacancies, resulting in lower resistance. ru.

[0421] The thickness of the conductive films 112, 120a, and 120b is between 30 nm and 500 nm. Alternatively, the wavelength can be between 100 nm and 400 nm.

[0422] [Transistor Configuration Example 2] Next, regarding a configuration different from the transistors shown in Figures 34(A), 34(B), and 34(C), see Figure 35( We will explain using A), (B), and (C).

[0423] Figure 35(A) is a top view of transistor 100A, and Figure 35(B) is a top view of Figure 35(A). Figure 35(C) is a cross-sectional view between the dashed line X1-X2, and Figure 35(A) is a cross-sectional view between the dashed line Y1- This is a cross-sectional view between Y2.

[0424] The transistor 100A shown in Figures 35(A), (B), and (C) is connected to the conductive film 10 on the substrate 102. 6, an insulating film 104 on the conductive film 106, an oxide semiconductor film 108 on the insulating film 104, and acid An insulating film 110 on the semiconductor film 108, a conductive film 112 on the insulating film 110, and an insulating film 10 4. It comprises an oxide semiconductor film 108 and an insulating film 116 on a conductive film 112. The semiconductor film 108 has a channel region 108i that overlaps with the conductive film 112, and an insulating film 116. It has a source region 108s that is in contact with the insulating film 116 and a drain region 108d that is in contact with the insulating film 116. .

[0425] In addition to the configuration of transistor 100 shown above, transistor 100A also has a conductive film 106 and It has an opening 143 and

[0426] The opening 143 is provided in the insulating films 104 and 110. The conductive film 106 is... The conductive film 112 is electrically connected through the opening 143. Therefore, the conductive film 106 and The same potential is applied to the conductive film 112. Note that the conductive film 10 is not provided with an opening 143. 6 and the conductive film 112 may be given different potentials. Alternatively, without providing the opening 143. The conductive film 106 may also be used as a light-shielding film. For example, the conductive film 106 may be made of a light-shielding material. By forming this, it is possible to suppress the light from below that irradiates the channel region 108i. Cut.

[0427] Furthermore, in the case of the transistor 100A configuration, the conductive film 106 is the first gate electrode ( The conductive film 112 functions as a second gate electrode (also called a bottom gate electrode), and the conductive film 112 is a second gate electrode ( It functions as a top gate electrode (also called a top gate electrode). The insulating film 104 also functions as a first gate electrode. The insulating film 110 has the function of a second gate insulating film. ru.

[0428] The conductive film 106 is made of the same material as the conductive films 112, 120a, and 120b described above. It can be used. In particular, by forming the conductive film 106 with a copper-containing material, resistance can be achieved. This is preferable because it can lower the coefficient of error. For example, the conductive film 106 is a titanium nitride film, a titanium nitride film A laminated structure is provided in which a copper film is provided on a tungsten film or a conductive film 120a, 12 0b is a laminated structure in which a copper film is provided on a titanium nitride film, a tantalum nitride film, or a tungsten film. This is preferable. In this case, transistor 100A is the pixel transistor of the display device and By using it in either one or both of the drive transistors, conductive film 106 and conductive film 1 Parasitic capacitance that occurs between 20a and the conductive film 106 and the conductive film 120b The capacity can be reduced. Therefore, conductive film 106, conductive film 120a, and conductive film 120b is used as the first gate electrode, source electrode, and drain electrode of transistor 100A. In addition to being used as such, it can also be used for wiring for power supply, signal supply, or connection of a display device. It can also be used for wiring and other purposes.

[0429] Thus, the transistor 100A shown in Figures 35(A), (B), and (C) is as explained earlier. Unlike transistor 100, gate electrodes function above and below the oxide semiconductor film 108. It is a structure having a conductive film. As shown in transistor 100A, one embodiment of the present invention is a semiconductor The device may be equipped with multiple gate electrodes.

[0430] Furthermore, as shown in Figures 35(B) and 35(C), the oxide semiconductor film 108 is the first gate electrode The conductive film 106 functions as a gate electrode, and the conductive film 112 functions as a second gate electrode. It is positioned opposite to it and sandwiched between two conductive films that function as gate electrodes.

[0431] Furthermore, the length of the conductive film 112 in the channel width direction is the same as the length of the oxide semiconductor film 108 in the channel width direction. The entire channel width direction of the oxide semiconductor film 108 is longer than the length in the direction of the insulating film 110. It is sandwiched between and covered by the conductive film 112. Also, the conductive film 112 and the conductive film 106 are insulating films. Since they are connected at the opening 143 provided in 104 and the insulating film 110, the oxide semiconductor One side of the conductive film 108 in the channel width direction has a conductive film 112 sandwiched between it and an insulating film 110. It is in opposition to that.

[0432] In other words, in the channel width direction of transistor 100A, the conductive film 106 and the conductive The film 112 is connected at the opening 143 provided in the insulating film 104 and the insulating film 110. At the same time, the oxide semiconductor film 108 is surrounded by insulating film 104 and insulating film 110 sandwiched in between. It has a complex structure.

[0433] With this configuration, the oxide semiconductor film 10 included in the transistor 100A 8 is a conductive film 106 that functions as a first gate electrode and a second gate electrode that functions as a second gate electrode. The conductive film 112 can electrically surround the transistor 100A. Thus, a channel region is formed by the electric fields of the first and second gate electrodes. The device structure of the transistor electrically surrounding the oxide semiconductor film 108 is called Surro This can be called an unded channel (S-channel) structure.

[0434] Since transistor 100A has an S-channel structure, the conductive film 106 or The conductive film 112 effectively induces an electric field in the oxide semiconductor film 108 to create a channel. Because it can be applied to the transistor, the current driving capability of the 100A transistor is improved, resulting in a high ON It becomes possible to obtain current characteristics. Also, it is possible to increase the on-current, It becomes possible to miniaturize transistor 100A. Also, transistor 100A is a guide Because it has a structure surrounded by the electrode 106 and the conductive film 112, the transistor 1 The mechanical strength of 00A can be increased.

[0435] Furthermore, in the channel width direction of transistor 100A, the aperture of the oxide semiconductor film 108 An opening different from the opening 143 may be formed on the side where section 143 is not formed.

[0436] Furthermore, as shown in transistor 100A, the transistor has a semiconductor film sandwiched between them. If there is a pair of gate electrodes, one gate electrode receives signal A, and the other gate electrode receives signal A. A fixed potential Vb may be applied to one of the terminal electrodes. Also, signal A is applied to one terminal electrode, while the other electrode is not. A signal B may be applied to one of the gate electrodes. Also, a fixed potential V may be applied to the other gate electrode. A fixed potential Vb may be applied to the other terminal electrode.

[0437] Signal A is, for example, a signal for controlling a conduction state or a non-conduction state. Signal A is A digital signal that takes two types of potentials: potential V1 or potential V2 (where V1 > V2). It is acceptable. For example, it is possible to set potential V1 as the high power supply potential and potential V2 as the low power supply potential. Yes, it's possible. Signal A can be an analog signal.

[0438] The fixed potential Vb is, for example, a potential used to control the threshold voltage VthA of a transistor. The fixed potential Vb may be potential V1 or potential V2. In this case, the fixed electric It is preferable that there is no need to provide a separate potential generation circuit for generating the potential Vb. Fixed potential Vb The potential Vb may be different from the potential V1 or potential V2. Therefore, the threshold voltage VthA can be increased in some cases. As a result, the gate-source voltage Reduces drain current when Vgs is 0V, and reduces leakage current in circuits with transistors. It may be possible to reduce it. For example, the fixed potential Vb may be lower than the low power supply potential. Therefore, by increasing the fixed potential Vb, it is sometimes possible to lower the threshold voltage VthA. As a result, the drain current is improved when the gate-source voltage Vgs is at a high power supply potential. In some cases, the operating speed of a circuit containing a transistor can be improved. For example, by lowering the fixed potential Vb. It is acceptable to set the potential higher than the power supply potential.

[0439] Signal B is, for example, a signal to control a conduction or non-conduction state. A digital signal that takes two types of potentials: potential V3 or potential V4 (where V3 > V4). It is acceptable. For example, it is possible to set potential V3 as the high power supply potential and potential V4 as the low power supply potential. Yes, it's possible. Signal B can also be an analog signal.

[0440] If both signal A and signal B are digital signals, signal B will have the same digital value as signal A. It may also be a signal that has. In this case, the on current of the transistor is increased, and the transistor In some cases, the operating speed of the circuit can be improved. At this time, the potential V1 and in signal A Potential V2 may be different from potentials V3 and V4 in signal B. For example, The gate insulating film corresponding to the gate to which signal B is input corresponds to the gate to which signal A is input. If the gate insulating film is thicker than the gate insulating film, the potential amplitude of signal B (V3-V4) is the same as the potential amplitude of signal A. It is also acceptable to make it larger than (V1-V2). Doing so will improve the conduction state of the transistor or The effect of signal A on the non-conductive state and the effect of signal B should be made equal. There are cases where this is possible.

[0441] If both signal A and signal B are digital signals, then signal B will have a different digital value from signal A. The signal may also have two properties. In this case, the control of the transistor is separated by signal A and signal B. This can be done in various ways, and in some cases, higher functionality can be achieved. For example, if the transistor is n In the case of a channel type, if signal A is at potential V1 and signal B is at potential V3, When both are in a conductive state, or when signal A is at potential V2 and signal B is at potential V4 If only one transistor is in a non-conductive state, then a single transistor can be used to perform functions such as NAND gates and NOR gates. In some cases, this functionality can be achieved. Furthermore, signal B is a signal for controlling the threshold voltage VthA. It may also be a number. For example, signal B is the period during which the circuit with the transistor is operating. The signal may have a different potential during the period when the circuit is not operating. Signal B is, The signals may have different potentials depending on the operating mode of the circuit. In this case, signal B is signal A The electrical potential may not switch as frequently as it should.

[0442] If both signal A and signal B are analog signals, then signal B will have the same potential as signal A. A signal, an analog signal obtained by multiplying the potential of signal A by a constant, or the potential of signal A added by a constant. Alternatively, a subtracted analog signal may also be used. In this case, the on-current of the transistor is This can improve the operating speed of circuits with transistors. Signal B is a signal A different analog signal may also be used. In this case, the control of the transistor is controlled by signal A and signal A. This can sometimes be done separately by B, which may allow for higher functionality.

[0443] Signal A may be a digital signal and signal B may be an analog signal. Or signal A may be It is an analog signal, and signal B may also be a digital signal.

[0444] When a fixed potential is applied to both gate electrodes of a transistor, the transistor is a resistive element. In some cases, it can function as an equivalent element. For example, a transistor can function as an n-channel element. In the case of a Nell type, by raising (lowering) the fixed potential Va or fixed potential Vb, In some cases, the effective resistance of the zista can be lowered (or raised). Fixed potential Va and fixed electric By increasing (or decreasing) both positions Vb, a transistor with only one gate can perform the operation. In some cases, an effective resistance lower (or higher) than the desired effective resistance may be obtained.

[0445] The other configurations of transistor 100A are the same as those of transistor 100 shown above. Yes, and it produces a similar effect.

[0446] Furthermore, an insulating film may be formed on transistor 100A. An example of this case is shown below. This is shown in Figures 36(A) and 36(B). Figures 36(A) and 36(B) are cross-sectional views of transistor 100B. The top view of transistor 100B is shown in Figure 35(A), which is transistor 100A. Since it is similar to the previous explanation, we will omit the explanation here.

[0447] The transistor 100B shown in Figures 36(A) and 36(B) consists of conductive films 120a and 120b, and an insulating film. The film 118 has an insulating film 122. For other configurations, see transistor 100A. It is similar to and produces the same effect.

[0448] The insulating film 122 has the function of flattening irregularities caused by transistors, etc. The film 122 can be insulating and can be formed using inorganic or organic materials. The inorganic material includes silicon oxide film, silicon oxide nitride film, silicon nitride oxide film, and nitride Examples include silicon films, aluminum oxide films, aluminum nitride films, etc. The organic material is... Examples include photosensitive resin materials such as acrylic resin or polyimide resin. .

[0449] [Transistor Configuration Example 3] Next, regarding a configuration different from the transistors shown in Figures 35(A), 35(B), and 35(C), see Figure 37. This will be explained using Figure 39.

[0450] Figures 37(A) and 37(B) are cross-sectional views of transistor 100C, and Figures 38(A) and 38(B) are Figure 39(A)(B) shows a cross-sectional view of transistor 100D, and Figure 39(A)(B) shows a cross-sectional view of transistor 100E. This is a cross-sectional view of transistor 100C, transistor 100D, and transistor The top view of transistor 100E is the same as that of transistor 100A shown in Figure 35(A). I will omit the explanation here.

[0451] The transistor 100C shown in Figures 37(A) and 37(B) has a layered structure of conductive film 112, conductive film The shape of 112 and the shape of the insulating film 110 are different from those of transistor 100A.

[0452] The conductive film 112 of transistor 100C is conductive film 112_1 on the insulating film 110, and It has a conductive film 112_2 on a film 112_1. For example, the conductive film 112_1 is acid By using a hydrocarbon conductive film, excess oxygen can be added to the insulating film 110. The oxide conductive film is formed using the sputtering method in an atmosphere containing oxygen gas. This can be done. Furthermore, as the above oxide conductive film, for example, an oxide having indium and tin A substance, an oxide having tungsten and indium, tungsten, indium and zinc Oxides containing titanium and indium, oxides containing titanium, indium and tin Oxides, oxides having indium and zinc, acids having silicon, indium and tin Examples include oxides containing indium, gallium, and zinc.

[0453] Furthermore, as shown in Figure 37(B), in the opening 143, the conductive film 112_2 and the conductive The film 106 is connected. When forming the opening 143, the conductive film that becomes the conductive film 112_1 After forming the opening 143, the shape shown in Figure 37(B) can be achieved. It is possible. When an oxide conductive film is applied to conductive film 112_1, conductive film 112_2 and conductive film 1 By configuring it so that 06 is connected, the connection resistance between conductive film 112 and conductive film 106 is reduced. It is possible.

[0454] Furthermore, the conductive film 112 and insulating film 110 of transistor 100C have a tapered shape. More specifically, the lower end of the conductive film 112 is formed outside the upper end of the conductive film 112. Furthermore, the lower end of the insulating film 110 is formed outside the upper end of the insulating film 110. Furthermore, the lower end of the conductive film 112 is formed at approximately the same position as the upper end of the insulating film 110.

[0455] By making the conductive film 112 and insulating film 110 of transistor 100C tapered, Compared to the case where the conductive film 112 and insulating film 110 of transistor 100A are rectangular, insulating film 1 It is preferable because it can improve the coverage of 16.

[0456] The other configurations of transistor 100C are the same as those of transistor 100A shown earlier. And it produces a similar effect.

[0457] The transistor 100D shown in Figures 38(A) and 38(B) has a layered structure of conductive film 112, conductive film The shape of 112 and the shape of the insulating film 110 are different from those of transistor 100A.

[0458] The conductive film 112 of transistor 100D is conductive film 112_1 on insulating film 110, and It has a conductive film 112_2 on film 112_1, and the lower end of conductive film 112_1 is It is formed outside the upper end of the conductive film 112_2. For example, conductive film 112_1 and conductive The film 112_2 and the insulating film 110 are processed with the same mask, and the conductive film 112_2 is wet The conductive film 112_1 and the insulating film 110 were etched by a dry etching method, respectively. The above structure can be achieved through processing.

[0459] Furthermore, by adopting the structure of transistor 100D, region 1 is formed in the oxide semiconductor film 108. Region 08f may be formed. Region 108f consists of channel region 108i and source region 1 It is formed between 08s and the channel region 108i and the drain region 108d.

[0460] Region 108f functions as either a high-resistance region or a low-resistance region. The anti-region has the same resistance as the channel region 108i and functions as a conductive gate electrode. This is a region where film 112 does not overlap. If region 108f is a high-resistance region, then region 108f is It functions as a so-called offset region. In order to suppress the decrease in the on-current of transistor 100D, the channel length (L In the direction, the region 108f should be 1 μm or less.

[0461] Furthermore, the low-resistance region is the region where the resistance is lower than that of the channel region 108i, and also the source region 10 This region has higher resistance than 8s and the drain region 108d. Region 108f is a low-resistance region. In this case, region 108f is a so-called LDD (Lightly Doped Drain) region. It functions as a region. When region 108f functions as an LDD region, the drain Because the electric field in the region can be relaxed, the threshold of the transistor caused by the electric field in the drain region can be reduced. This can reduce fluctuations in the voltage value.

[0462] Furthermore, if region 108f is to be the LDD region, for example, from insulating film 116 to region 10 8f is supplied with one or more of nitrogen, hydrogen, and fluorine, or insulating film 110 and conductive film 11 By using 2_1 as a mask and adding impurity elements from above the conductive film 112_1, Impurities pass through the conductive film 112_1 and the insulating film 110 and are added to the oxide semiconductor film 108. It can be formed by doing so.

[0463] Furthermore, as shown in Figure 38(B), in the opening 143, the conductive film 112_2 and the conductive The membrane 106 is connected to it.

[0464] The other configurations of transistor 100D are the same as those of transistor 100A shown earlier. And it produces a similar effect.

[0465] The transistor 100E shown in Figures 39(A) and 39(B) has a layered structure of conductive film 112, conductive film The shape of 112 and the shape of the insulating film 110 are different from those of transistor 100A.

[0466] The conductive film 112 of transistor 100E is conductive film 112_1 on insulating film 110, and It has a conductive film 112_2 on film 112_1, and the lower end of conductive film 112_1 is It is formed outside the lower end of the conductive film 112_2. Also, the lower end of the insulating film 110 is conductive It is formed outside the lower end of the conductive film 112_1. For example, conductive film 112_1 and conductive film 112_2 and insulating film 110 are processed with the same mask, and conductive film 112_2 and conductive film 1 12_1 was processed by the wet etching method, and the insulating film 110 was processed by the dry etching method. By performing the necessary modifications, the above structure can be achieved.

[0467] Also, similar to transistor 100D, transistor 100E has an oxide semiconductor film 1 Region 108f may be formed within 08. Region 108f is channel region 108i Between the source region 108s and the channel region 108i and the drain region 108d It is formed in this way.

[0468] Furthermore, as shown in Figure 39(B), in the opening 143, the conductive film 112_2 and the conductive The membrane 106 is connected to it.

[0469] The other configurations of transistor 100E are the same as those of transistor 100A shown earlier. And it produces a similar effect.

[0470] [Transistor Configuration Example 4] Next, regarding a configuration different from transistor 100A shown in Figures 35(A), (B), and (C), This will be explained using Figures 40 to 44.

[0471] Figures 40(A)(B) are cross-sectional views of transistor 100F, and Figures 41(A)(B) are Figure 42(A)(B) shows a cross-sectional view of transistor 100G, and Figure 42(A)(B) shows a cross-sectional view of transistor 100H. Figure 43(A)(B) is a cross-sectional view of transistor 100J, and Figure 44 (A) and (B) are cross-sectional views of transistor 100K. Note that transistor 100F, Transistor 100G, Transistor 100H, Transistor 100J, and Transistor The top view of transistor 100K is the same as that of transistor 100A shown in Figure 35(A). I will omit the explanation here.

[0472] Transistor 100F, Transistor 100G, Transistor 100H, Transistor 100J and transistor 100K are the same as transistor 100A and oxide semiconductor shown above. The structure of film 108 is different. Other components are the same as those of transistor 100A shown earlier. They have a similar configuration and produce the same effect.

[0473] The oxide semiconductor film 108 of the transistor 100F shown in Figures 40(A)(B) is an oxide semiconductor film. The oxide semiconductor film 108_1 on the edge film 104, and the oxide semiconductor film on the oxide semiconductor film 108_1 It has a body film 108_2 and an oxide semiconductor film 108_3 on the oxide semiconductor film 108_2. Furthermore, the channel region 108i, the source region 108s, and the drain region 108d are These are oxide semiconductor film 108_1, oxide semiconductor film 108_2, and oxide semiconductor film, respectively. It has a 3-layer laminated structure of 108_3.

[0474] The oxide semiconductor film 108 of the transistor 100G shown in Figure 41(A)(B) is an oxide semiconductor film. The oxide semiconductor film 108_2 on the edge film 104, and the oxide semiconductor film on the oxide semiconductor film 108_2 It has a body membrane 108_3, and a channel region 108i, a source region 108s, and The drain region 108d is comprised of oxide semiconductor film 108_2 and oxide semiconductor film 1 It has a two-layer laminated structure of 08_3.

[0475] The oxide semiconductor film 108 of the transistor 100H shown in Figure 42(A)(B) is an insulating film. The oxide semiconductor film 108_1 on the edge film 104, and the oxide semiconductor film on the oxide semiconductor film 108_1 It has a body membrane 108_2, and a channel region 108i, a source region 108s, and The drain region 108d consists of oxide semiconductor film 108_1 and oxide semiconductor film 1 It has a two-layer laminated structure of 08_2.

[0476] The oxide semiconductor film 108 of the transistor 100J shown in Figure 43(A)(B) is an insulating film. The oxide semiconductor film 108_1 on the edge film 104, and the oxide semiconductor film on the oxide semiconductor film 108_1 It has a body film 108_2 and an oxide semiconductor film 108_3 on the oxide semiconductor film 108_2. Furthermore, the channel region 108i is an oxide semiconductor film 108_1, an oxide semiconductor film 108 _2, and the oxide semiconductor film 108_3 are stacked in a three-layer structure, with the source region 108s and The drain region 108d is an oxide semiconductor film 108_1 and an oxide semiconductor film It has a 108_2 two-layer stacked structure. Note that the channel width (W) of transistor 100J is... In the cross-section, the oxide semiconductor film 108_3 is made up of oxide semiconductor film 108_1 and oxide It covers the side surface of the semiconductor film 108_2.

[0477] The oxide semiconductor film 108 of the transistor 100K shown in Figures 44(A) and 44(B) is an insulating film. The oxide semiconductor film 108_2 on the edge film 104, and the oxide semiconductor film on the oxide semiconductor film 108_2 It has a body film 108_3 and a channel region 108i, which is an oxide semiconductor film 108_ 2, and the oxide semiconductor film 108_3 are stacked in a two-layer structure, with the source region 108s and Each drain region 108d is a single-layer structure of the oxide semiconductor film 108_2. In the cross-section of the transistor 100K in the channel width (W) direction, the oxide semiconductor film 108 _3 covers the side surface of the oxide semiconductor film 108_2.

[0478] On the side surface or near the channel width (W) direction of the channel region 108i, processing Damage in this area makes it easy for defects (e.g., oxygen deficiencies) to form, or impurities It is easily contaminated by adhesion. Therefore, even if channel region 108i is substantially intrinsic When stress such as an electric field is applied, the channel width of channel region 108i ( The side surface in the W direction or its vicinity is activated, making it prone to becoming a low-resistance (n-type) region. If the side surface or its vicinity in the channel width (W) direction of channel region 108i is an n-type region, Because the n-type region in question serves as a carrier path, parasitic channels may be formed.

[0479] Therefore, in transistors 100J and 100K, the channel region The 108i is configured as a stacked structure, and the side surface of the channel region 108i in the channel width (W) direction is stacked. The structure is configured to cover one layer. This configuration allows the side of the channel region 108i to be covered. or suppress defects in the vicinity of or near the channel region 108i This makes it possible to reduce the adhesion of impurities to the material.

[0480] [Band structure] Here, insulating film 104, oxide semiconductor films 108_1, 108_2, 108_3, and The band structure of the edge film 110, the insulating film 104, the oxide semiconductor films 108_2, 108_3, and The band structure of insulating film 110, and insulating film 104, oxide semiconductor film 108_1, 108_ The band structure of 2 will be explained using Figures 45(A), (B), and (C). Note that Figure 45( A)(B)(C) are the band structures in the channel region 108i.

[0481] Figure 45(A) shows insulating film 104 and oxide semiconductor films 108_1, 108_2, and 108_3. This is an example of a band structure in the film thickness direction of a laminated structure having an insulating film 110. Also, Figure 4 5(B) consists of insulating film 104, oxide semiconductor films 108_2, 108_3, and insulating film 110 This is an example of a band structure in the film thickness direction of a laminated structure having the above characteristics. Figure 45(C) also shows an insulating film. A stacked structure having 104, oxide semiconductor films 108_1, 108_2, and insulating film 110 This is an example of the band structure in the film thickness direction. Note that the band structure is shown for ease of understanding of the insulating film. 104, conduction of oxide semiconductor films 108_1, 108_2, 108_3, and insulating film 110 This shows the energy level (Ec) at the bottom of the belt.

[0482] Furthermore, Figure 45(A) shows that silicon oxide films are used as insulating films 104 and 110, and oxide semi-oxide films are used. Conductor film 108_1 has a metal oxide with an atomic ratio of metal elements of In:Ga:Zn=1:3:2. Using an oxide semiconductor film formed with a material target, the oxide semiconductor film 108_2 is used. A metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 4:2:4.1 is used. Using an oxide semiconductor film formed by this process, the oxide semiconductor film 108_3 contains atoms of a metal element. Oxides formed using metal oxide targets with a numerical ratio of In:Ga:Zn = 1:3:2 This is a band diagram of a configuration using a semiconductor film.

[0483] Furthermore, Figure 45(B) shows that silicon oxide films are used as insulating films 104 and 110, and oxide semi-oxide films are used. The conductive film 10⁸⁻² has an atomic ratio of metal elements of In:Ga:Zn = 4:2:4.1. Using an oxide semiconductor film formed with an oxide target, oxide semiconductor film 108_3 As such, a metal oxide target with an atomic ratio of metal elements of In:Ga:Zn=1:3:2 is used. This is a band diagram of a configuration using an oxide semiconductor film formed by [processing].

[0484] Furthermore, Figure 45(C) shows that silicon oxide films are used as insulating films 104 and 110, and oxide semi-oxide films are used. Conductor film 108_1 has a metal oxide with an atomic ratio of metal elements of In:Ga:Zn=1:3:2. Using an oxide semiconductor film formed with a material target, the oxide semiconductor film 108_2 is used. A metal oxide target with an atomic ratio of metal elements of In:Ga:Zn = 4:2:4.1 is used. A band configuration using an oxide semiconductor film formed by This is a diagram.

[0485] As shown in Figure 45(A), the oxide semiconductor films 108_1, 108_2, and 108_3 As shown in Figure 45(B), the energy levels at the lower end of the conduction band change smoothly. In the oxide semiconductor films 108_2 and 108_3, the energy level at the lower end of the conduction band is The change is gradual. Also, as shown in Figure 45(C), the oxide semiconductor film 108_1, 1 In 08_2, the energy levels at the lower end of the conduction band change smoothly. In other words, It can also be said that it changes continuously or joins continuously. For example, at the interface between oxide semiconductor film 108_1 and oxide semiconductor film 108_2, or the oxide At the interface between the semiconductor film 108_2 and the oxide semiconductor film 108_3, trap centers and regeneration Assume that there are no impurities that form defect levels such as convergent centers.

[0486] In order to form a continuous junction between oxide semiconductor films 108_1, 108_2, and 108_3, Using a multi-chamber type film deposition apparatus (sputtering apparatus) equipped with a load lock chamber Therefore, it is necessary to continuously stack each film without exposing it to the atmosphere.

[0487] By using the configuration shown in Figures 45(A), (B), and (C), the oxide semiconductor film 108_2 forms a well (Well) In a transistor using the above stacked structure, the channel region is an oxide semiconductor It can be seen that it is formed on the conductive film 108_2.

[0488] Furthermore, by providing oxide semiconductor films 108_1 and 108_3, the oxide semiconductor film 1 Defect levels that may form on 08_2 can be kept away from the oxide semiconductor film 108_2. .

[0489] Furthermore, the lower end of the conduction band of the oxide semiconductor film 108_2 where the defect level functions as a channel region. The energy level (Ec) can be farther from the vacuum level than the defect level, and electrons can accumulate in the defect level. This makes it easier for electrons to accumulate in the defect levels, resulting in a negative fixed charge. Therefore, the transistor's threshold voltage shifts in the positive direction. Consequently, the defect level The energy level (Ec) at the lower end of the conduction band of the oxide semiconductor film 108_2 is closer to the vacuum level. It is preferable to have a configuration that makes it difficult for electrons to accumulate at defect levels. This makes it possible to increase the on-current of the transistor, as well as the field-effect mobility. It can improve.

[0490] Furthermore, oxide semiconductor films 108_1 and 108_3 transmit more efficiently than oxide semiconductor film 108_2. The energy level at the lower end of the guide band is close to the vacuum level, and typically, in oxide semiconductor film 108_2 The energy levels at the lower end of the conduction band and the lower end of the conduction band of oxide semiconductor films 108_1 and 108_3 The difference from the energy level is 0.15 eV or greater, or 0.5 eV or greater and 2 eV or less. Or it is less than 1 eV. That is, electron affinity of oxide semiconductor films 108_1 and 108_3 The difference between the force and the electron affinity of the oxide semiconductor film 108_2 is 0.15 eV or greater, or 0. It is 5 eV or more and 2 eV or less, or 1 eV or less.

[0491] With this configuration, the oxide semiconductor film 108_2 becomes the main current path. In other words, the oxide semiconductor film 108_2 has the function of a channel region, and the oxide semiconductor Films 108_1 and 108_3 function as oxide insulating films. Furthermore, oxide semiconductors... Films 108_1 and 108_3 constitute the oxide semiconductor film 108_2 in which the channel region is formed. It is preferable to use an oxide semiconductor film composed of one or more of the metal elements that make up the film. By adopting this configuration, the interface between the oxide semiconductor film 108_1 and the oxide semiconductor film 108_2, Alternatively, at the interface between the oxide semiconductor film 108_2 and the oxide semiconductor film 108_3, interfacial dispersion Disturbance is less likely to occur. Therefore, carrier movement is not hindered at this interface, The field-effect mobility of the inverter increases.

[0492] Furthermore, the oxide semiconductor films 108_1 and 108_3 function as part of the channel region. To prevent this, materials with sufficiently low conductivity shall be used. Conductor films 108_1 and 108_3 are, based on their physical properties and / or functions, oxide insulating films, respectively. It can also be called a film. Alternatively, oxide semiconductor films 108_1 and 108_3 have electron affinity (vacuum The difference between the energy level and the energy level at the bottom of the conduction band is smaller than that of the oxide semiconductor film 10⁸⁻². The energy level at the bottom of the conduction band is the energy level at the bottom of the conduction band of the oxide semiconductor film 108_2 A material with a difference (band offset) shall be used. Also, the magnitude of the drain voltage In order to suppress the occurrence of threshold voltage differences that depend on the material, the oxide semiconductor film 108 The energy levels at the lower end of the conduction band of _1 and 10⁸_3 are the same as the energy levels at the lower end of the conduction band of the oxide semiconductor film 10⁸_2. It is preferable to use a material whose energy level is closer to the vacuum level than the lower limit energy level. For example, an oxide. The energy levels at the lower end of the conduction band of semiconductor film 108_2 and oxide semiconductor films 108_1, 10 The difference between the energy level of the lower end of the conduction band at 8_3 and the current level is 0.2 eV or greater, preferably 0.5 eV. It is preferable to keep the above in place.

[0493] Furthermore, the oxide semiconductor films 108_1 and 108_3 contain a spinel-type crystal structure within the film. It is preferable that spinel-type crystals do not form in the oxide semiconductor films 108_1 and 108_3. If a crystalline structure is present, at the interface between the spinel-type crystalline structure and other regions, the conductive film 120 In some cases, the constituent elements of a and 120b may diffuse into the oxide semiconductor film 108_2. When the oxide semiconductor films 108_1 and 108_3 are CAAC-OS as described later, the conductive film The blocking properties of the constituent elements of 120a and 120b, such as copper, become higher, which is preferable.

[0494] Furthermore, in this embodiment, the oxide semiconductor films 108_1 and 108_3 are metal The atomic ratio of elements is formed using a metal oxide target with In:Ga:Zn = 1:3:2. Although examples have been given of configurations using an oxide semiconductor film, the system is not limited to this. For example, acid For ionized semiconductor films 10⁸⁻¹ and 10⁸⁻³, In:Ga:Zn = 1:1:1 [atomic ratio] ], In:Ga:Zn=1:1:1.2[atomic ratio], In:Ga:Zn=1:3:4[ [Atomic ratio] In:Ga:Zn=1:3:6 [Atomic ratio] In:Ga:Zn=1:4 5 [atomic ratio], In:Ga:Zn = 1:5:6 [atomic ratio], or In:Ga:Zn Oxide semiconductor film formed using a metal oxide target with an atomic ratio of 1:10:1 Alternatively, the oxide semiconductor films 108_1 and 108_3 may be made of metal elements. Oxide semiconductors formed using a metal oxide target with an atomic ratio of Ga:Zn = 10:1 A body film may also be used. In this case, the atomic ratio of the metal elements in the oxide semiconductor film 108_2 is Oxide semiconductor formed using a metal oxide target with an In:Ga:Zn=1:1:1 ratio. Using films, the atomic ratio of metal elements is set as oxide semiconductor films 10⁸⁻¹ and 10⁸⁻³, with Ga:Z. When an oxide semiconductor film is formed using a metal oxide target with n=10:1, acid The energy levels at the lower end of the conduction band of the oxide semiconductor film 108_2 and the oxide semiconductor film 108_1, The difference between the energy level at the lower end of the conduction band of 10⁸³ can be set to 0.6 eV or more. It is suitable.

[0495] Note that the oxide semiconductor films 108_1 and 108_3 are defined as In:Ga:Zn=1:1:1 When using a metal oxide target with [atomic ratio], oxide semiconductor film 108_1, 108 _3 is the case where In:Ga:Zn = 1:β1 (0 < β1 ≤ 2):β2 (0 < β2 ≤ 2) There is a combination. Also, as oxide semiconductor films 10⁸⁻¹ and 10⁸⁻³, In:Ga:Zn=1 When using a metal oxide target with an atomic ratio of 3:4, the oxide semiconductor film 108_1 , 10⁸⁻³ is In:Ga:Zn = 1:β3 (1≦β3≦5):β4 (2≦β4≦6) This can sometimes occur. Also, as oxide semiconductor films 108_1 and 108_3, In:Ga: When using a metal oxide target with Zn=1:3:6 [atomic ratio], the oxide semiconductor film 1 08_1 and 108_3 are In:Ga:Zn=1:β5(1≦β5≦5):β6(4≦β There are cases where 6 ≤ 8.

[0496] This embodiment may be appropriately combined with other embodiments described herein, at least in part. They can be implemented in combination.

[0497] (Embodiment 3) In this embodiment, the transistor that can be used in a semiconductor device according to one aspect of the present invention is I will explain this in detail.

[0498] In this embodiment, the bottom-gate type transistor is shown in Figures 46 to 52. We will explain using this method.

[0499] [Transistor Configuration Example 1] Figure 46(A) is a top view of transistor 300A, and Figure 46(B) is a top view of transistor 300A. This corresponds to a cross-sectional view of the section between the dashed line X1 and X2 shown in Figure 4, and Figure 46(C) is the same as Figure 4 This corresponds to the cross-sectional view of the section between Y1 and Y2 shown by the dashed line in 6(A). Note that this is shown in Figure 46. In (A), to avoid complexity, some of the components of transistor 300A are shown. The diagram omits details such as the insulating film that functions as a gate insulating film. Also, the dashed line X1 -When the X2 direction is referred to as the channel length direction, and the Y1-Y2 direction (marked with a dashed line) is referred to as the channel width direction. There is. Furthermore, in the top view of the transistor, the following drawings also refer to Figure 46(A) and Similarly, some components may be omitted when illustrating.

[0500] The transistor 300A shown in Figure 46 has a conductive film 304 on the substrate 302 and the substrate 302 and And insulating film 306 on conductive film 304, insulating film 307 on insulating film 306, and insulating film 307 The oxide semiconductor film 308, the conductive film 312a on the oxide semiconductor film 308, and the oxide semiconductor It has a conductive film 312b on film 308. Also, on transistor 300A, more details In addition, insulating films 314 and 316 are located on the conductive films 312a and 312b and the oxide semiconductor film 308. And an insulating film 318 is provided.

[0501] Furthermore, in transistor 300A, insulating films 306 and 307 are in transistor 300 A functions as a gate insulating film, and insulating films 314, 316, and 318 are transistors. It functions as a protective insulating film for transistor 300A. In addition, in transistor 300A, The electrode film 304 functions as a gate electrode, and the conductive film 312a functions as a source electrode. The conductive film 312b has a function, and it functions as a drain electrode.

[0502] Furthermore, in this specification, insulating films 306 and 307 are referred to as the first insulating film, and insulating film 314, 316 is sometimes referred to as the second insulating film, and insulating film 318 as the third insulating film. .

[0503] The transistor 300A shown in Figure 46 has a channel-etched transistor structure. An oxide semiconductor film according to one aspect of the present invention is suitably used in channel etch type transistors. It is possible.

[0504] [Transistor Configuration Example 2] Figure 47(A) is a top view of transistor 300B, and Figure 47(B) is a top view of transistor 300B. This corresponds to a cross-sectional view of the section between the dashed line X1 and X2 shown in Figure 4, and Figure 47(C) is the same as Figure 4 This corresponds to the cross-sectional view of the section between the dashed line Y1 and Y2 shown in 7(A).

[0505] The transistor 300B shown in Figure 47 has a conductive film 304 on the substrate 302 and the substrate 302 and And insulating film 306 on conductive film 304, insulating film 307 on insulating film 306, and insulating film 307 The oxide semiconductor film 308, the insulating film 314 on the oxide semiconductor film 308, and the insulating film 314 The insulating film 316 and the opening 341a provided in the insulating film 314 and the insulating film 316 A conductive film 312a electrically connected to the oxide semiconductor film 308, an insulating film 314, and an insulating film. The oxide semiconductor film 308 is electrically connected through the opening 341b provided in 316. It has a conductive film 312b. Also, on transistor 300B, more specifically, conductive film 31 An insulating film 318 is provided on 2a, 312b, and insulating film 316.

[0506] Furthermore, in transistor 300B, insulating films 306 and 307 are in transistor 300 It functions as a gate insulating film for B, and insulating films 314 and 316 are oxide semiconductor films 308 The insulating film 318 functions as a protective insulating film for transistor 300B. It has the function of a gate. In addition, in transistor 300B, the conductive film 304 is the gate The conductive film 312a has the function of an electrode, and the conductive film 3 has the function of a source electrode. 12b functions as a drain electrode.

[0507] In transistor 300A shown in Figure 46, although it had a channel etch type structure In contrast, transistor 300B shown in Figures 47(A), (B), and (C) has a channel-protected structure. The oxide semiconductor film according to one aspect of the present invention is also suitable for channel-protected transistors. It can be used.

[0508] [Transistor Configuration Example 3] Figure 48(A) is a top view of transistor 300C, and Figure 48(B) is a top view of Figure 48(A) This corresponds to a cross-sectional view of the section between the dashed line X1 and X2 shown in Figure 4, and Figure 48(C) is the same as Figure 4 This corresponds to the cross-sectional view of the section between the dashed line Y1 and Y2 shown in 8(A).

[0509] The transistor 300C shown in Figure 48 is the same as the transistor shown in Figures 47(A), 47(B), and 47(C). The shapes of 300B and insulating films 314 and 316 are different. Specifically, transistor 300C The insulating films 314 and 316 are provided in an island-like manner on the channel region of the oxide semiconductor film 308. The other components are the same as those of the 300B transistor.

[0510] [Transistor Configuration Example 4] Figure 49(A) is a top view of transistor 300D, and Figure 49(B) is a top view of transistor 300D. This corresponds to a cross-sectional view of the section between the dashed line X1 and X2 shown in Figure 4, and Figure 49(C) is the same as Figure 4 This corresponds to the cross-sectional view of the section between the dashed line Y1 and Y2 shown in 9(A).

[0511] The transistor 300D shown in Figure 49 has a conductive film 304 on the substrate 302 and the substrate 302 and And insulating film 306 on conductive film 304, insulating film 307 on insulating film 306, and insulating film 307 The oxide semiconductor film 308, the conductive film 312a on the oxide semiconductor film 308, and the oxide semiconductor The conductive film 312b on film 308, the oxide semiconductor film 308, and the conductive films 312a and 312b The insulating film 314 on top, the insulating film 316 on the insulating film 314, and the insulating film 318 on the insulating film 316 It also has conductive films 320a and 320b on an insulating film 318.

[0512] Furthermore, in transistor 300D, insulating films 306 and 307 are in transistor 300 The insulating films 314, 316, and 318 function as the first gate insulating film of D, and the transistors It functions as the second gate insulating film of transistor 300D. Also, transistor 300 In D, the conductive film 304 functions as the first gate electrode, and the conductive film 320a The conductive film 320b functions as a second gate electrode, and the conductive film 320b is used as a pixel electrode in a display device. It has the function of a conductive film. Furthermore, the conductive film 312a has the function of a source electrode and is conductive. The film 312b functions as a drain electrode.

[0513] Furthermore, as shown in Figure 49(C), the conductive film 320a consists of insulating films 306, 307, 314, In the openings 342b and 342c provided in 316 and 318, the conductive film 304 is connected Therefore, conductive film 320a and conductive film 304 are given the same potential.

[0514] Furthermore, in transistor 300D, openings 342b and 342c are provided, and a conductive film 3 The example given illustrates a configuration in which 20a and the conductive film 304 are connected, but the system is not limited to this. , forming only one of the openings, either opening 342b or opening 342c, and the conductive film 3 A configuration that connects 20a and the conductive film 304, or provides openings 342b and 342c. Alternatively, the conductive film 320a and conductive film 304 may not be connected. In the configuration where 0a and conductive film 304 are not connected, conductive film 320a and conductive film 304 are not connected. Each can be given a different electrical potential.

[0515] Furthermore, the conductive film 320b is provided in the openings 342a in the insulating films 314, 316, and 318. It is connected to the conductive film 312b via this.

[0516] Furthermore, transistor 300D has the S-channel structure described earlier.

[0517] [Transistor Configuration Example 5] Furthermore, the oxide semiconductor film of transistor 300A shown in Figures 46(A), (B), and (C) 308 may be configured as a multi-layered structure. An example of this is shown in Figures 50(A)(B) and 51. (A)(B) are shown.

[0518] Figures 50(A)(B) are cross-sectional views of transistor 300E, and Figures 51(A)(B) are This is a cross-sectional view of transistor 300F. Also shown are the top surfaces of transistors 300E and 300F. The diagram is similar to that of transistor 300A shown in Figure 46(A).

[0519] The oxide semiconductor film 308 of the transistor 300E shown in Figure 50(A)(B) is acid Oxide semiconductor film 308_1, oxide semiconductor film 308_2, oxide semiconductor film 308_3 , has. Also, the oxide semiconductor of transistor 300F shown in Figure 51(A)(B) The body membrane 308 has an oxide semiconductor film 308_2 and an oxide semiconductor film 308_3.

[0520] Note that conductive film 304, insulating film 306, insulating film 307, oxide semiconductor film 308, oxide semiconductor Conductor film 308_1, oxide semiconductor film 308_2, oxide semiconductor film 308_3, conductive film 31 2a, 312b, insulating film 314, insulating film 316, insulating film 318, and conductive film 320a, 3 20b consists of the conductive film 106, insulating film 116, insulating film 114, and oxide film, as described above. Monocrystalline semiconductor film 108, oxide semiconductor film 108_1, oxide semiconductor film 108_2, oxide semiconductor Body film 108_3, conductive films 120a, 120b, insulating film 104, insulating film 118, insulating film 11 6. Materials similar to those used for the conductive film 112 can be used.

[0521] [Transistor Configuration Example 6] Figure 52(A) is a top view of transistor 300G, and Figure 52(B) is a top view of Figure 52(A). This corresponds to a cross-sectional view of the section between the dashed line X1 and X2 shown in Figure 5, and Figure 52(C) is the same as Figure 5 This corresponds to the cross-sectional view of the section between the dashed line Y1 and Y2 shown in 2(A).

[0522] The transistor 300G shown in Figure 52 has a conductive film 304 on the substrate 302 and the substrate 302 and And insulating film 306 on conductive film 304, insulating film 307 on insulating film 306, and insulating film 307 The oxide semiconductor film 308, the conductive film 312a on the oxide semiconductor film 308, and the oxide semiconductor The conductive film 312b on film 308, oxide semiconductor film 308, conductive film 312a, and conductive film 3 Insulating film 314 on 12b, insulating film 316 on insulating film 314, and conductive film on insulating film 316 It has 320a and a conductive film 320b on the insulating film 316.

[0523] Furthermore, insulating film 306 and insulating film 307 have an opening 351, insulating film 306 and insulating On film 307 is a conductive film 312 that is electrically connected to conductive film 304 via an opening 351. c is formed. Also, insulating film 314 and insulating film 316 have openings that reach the conductive film 312b. It has a section 352a and an opening 352b that reaches the conductive film 312c.

[0524] Furthermore, the oxide semiconductor film 308 is oxide semiconductor film 308_2 on the conductive film 304 side, It comprises an oxide semiconductor film 308_3 on a monocrystalline semiconductor film 308_2.

[0525] Furthermore, an insulating film 318 is provided on top of the transistor 300G. The insulating film 318 is It is formed to cover the insulating film 316, the conductive film 320a, and the conductive film 320b.

[0526] Furthermore, in transistor 300G, insulating films 306 and 307 are in transistor 300 The insulating films 314 and 316 function as the first gate insulating film of transistor 3. The insulating film 318 functions as the second gate insulating film of transistor 300. It functions as a protective insulating film for G. In addition, in transistor 300G, conductive film 3 04 functions as the first gate electrode, and the conductive film 320a functions as the second gate electrode. The conductive film 320b has the function of a pixel electrode used in a display device. Furthermore, in transistor 300G, the conductive film 312a functions as a source electrode. The conductive film 312b has the function of a drain electrode. Also, transistor 30 At 0G, the conductive film 312c functions as a connecting electrode.

[0527] Furthermore, the 300G transistor has the S-channel structure described earlier.

[0528] Furthermore, the structures of transistors 300A through 300G can be freely combined. They can be used together.

[0529] This embodiment may be appropriately combined with other embodiments described herein, at least in part. They can be implemented in combination.

[0530] (Embodiment 4) In this embodiment, a semiconductor device having a metal oxide film according to one aspect of the present invention is shown in Figure 5. This will be explained with reference to Figures 3 through 55.

[0531] <Example 1 of semiconductor device configuration> Figure 53 shows the transistor 300D shown in Embodiment 3 and the transistor shown in Embodiment 2 This is a cross-sectional view in the channel length (L) direction of an example where STA100B is used in a laminated structure.

[0532] By stacking transistor 300D and transistor 100B, The footprint required for the ZISTA can be reduced.

[0533] For example, by using the configuration shown in Figure 53 in the pixel section of a display device, the pixel density of the display device can be increased. This makes it possible to increase the pixel density of a display device to 1000 ppi (pixels). If the pixel density of the display device exceeds (per inch) or exceeds 2000 ppi Even in this case, by arranging them as shown in Figure 53, the aperture ratio of the pixels can be increased. Note that ppi is a unit that represents the number of pixels per inch.

[0534] Furthermore, by stacking transistor 300D and transistor 100B, The actual configuration will differ slightly from the one shown.

[0535] For example, in Figure 53, transistor 300D has a configuration different from the one shown above. ru.

[0536] The transistor 300D shown in Figure 53 has an insulating film 318 and a conductive film 320a that are insulated from each other. It has a film 319 and an insulating film 110a.

[0537] As the insulating film 319, the material shown for insulating film 314 or insulating film 316 can be used. The insulating film 319 is provided so that it does not come into contact with the oxide semiconductor film 108. It can be made. Also, as the insulating film 110a, the shape can be made by processing the same insulating film as insulating film 110. This is accomplished. Furthermore, the conductive film 320a of transistor 330D and transistor 100 The conductive film 112 possessed by B is formed by processing the same conductive film.

[0538] Furthermore, the transistor 100B shown in Figure 53 uses conductive film 312c instead of conductive film 106. It has. Also, transistor 100B shown in Figure 53 has an insulating film instead of insulating film 104. It has 314, 316, 318, and 319. The insulating film 104 is connected to the transistor 300D. By using insulating films 314, 316, 318, and 319, the transistor fabrication process is shortened. It can be done.

[0539] Furthermore, in Figure 53, the conductive film 344 is in contact with the conductive film 120b of transistor 300D. The conductive film 344 is transmitted through the opening 342 provided in the insulating film 122. It is electrically connected to the conductive film 120b. Also, the conductive film 344 is the conductive film 320a. A material that can be used for this purpose should be applied. Note that the conductive film 344 is used for the pixels of the display device. It functions as a pole.

[0540] Furthermore, in Figure 53, transistor 300D and transistor 100B are stacked in a stacked structure. While we have explained the case of construction, it is not limited to this. For example, as shown in Figures 54 and 55. It can also be used as a composition.

[0541] <Example of semiconductor device configuration 2> Figure 54 shows a stack of transistor 950 and transistor 100A as shown in Embodiment 2. This is a cross-sectional view in the channel length (L) direction, showing an example of a structure.

[0542] The transistor 950 shown in Figure 54 consists of a substrate 952 and an insulating film 954 on the substrate 952, A semiconductor film 956 on the insulating film 954, an insulating film 958 on the semiconductor film 956, and an insulating film 958 The conductive film 960 on top, the insulating film 954, the semiconductor film 956, and the insulating film 96 on the conductive film 960 2, the insulating film 964 on the insulating film 962, and the conductive film 9 that is electrically connected to the semiconductor film 956 It has 66a and 966b. In addition, an insulating film 968 is provided on the transistor 950. It can be done.

[0543] The semiconductor film 956 contains silicon. In particular, the semiconductor film 956 contains crystalline silicon. It is preferable to have it. Transistor 950 is a transistor using so-called low-temperature polysilicon. For example, a transistor using low-temperature polysilicon is used in the drive circuit of a display device. This is preferable because it allows for obtaining high field-effect mobility. Also, the transistor For example, using the TA300A in the pixel section of a display device is preferable because it can suppress power consumption. ru.

[0544] Furthermore, the substrate 952 can be a glass substrate, a plastic substrate, or the like. Furthermore, the insulating film 954 also functions as an underlayer insulating film for the transistor 950. The film 954 can be, for example, a silicon oxide film, a silicon nitride film, a silicon oxide nitride film, or a silicon nitride film. A silicon film or the like can be used. The insulating film 958 is the gate insulating film of the transistor 950. It functions as a film. The insulating film 958 is made from the materials listed for insulating film 954. This is possible. The conductive film 960 functions as the gate electrode of the transistor 950. The conductive film 960 includes the conductive films 312a, 312b, 120a, and 120b shown in the previous embodiment. The same materials as those used can be used. Insulating films 962, 964, and 968 are used in transistor 9 It has the function of a protective insulating film of 50. In addition, conductive films 966a and 966b transition It functions as the source electrode or drain electrode of STA 950. Conductive films 966a, 9 66b has conductive films 312a, 312b, 120a, 120b, etc. as shown in the previous embodiment. The same materials can be used.

[0545] Furthermore, between transistor 950 and transistor 300A, there is an insulating film 970 and an insulating film. An edge film 972 is provided. The insulating film 970 functions as a barrier film. Specifically The insulating film 970 contains impurities in the transistor 950, such as hydrogen. It is formed so as not to penetrate the 300A side. Also, the insulating film 972 is transistor It functions as a 300A underlayer insulating film.

[0546] For example, the insulating film 970 is a material that releases little hydrogen and can suppress hydrogen diffusion. Preferred. Examples of such materials include silicon nitride and aluminum oxide. The insulating film 972 preferably has excess oxygen, for example. The materials shown in the border films 314 and 316 can be used.

[0547] Furthermore, in Figure 54, transistor 950 and transistor 300A do not overlap. This structure is not limited to this, for example, the channel region of transistor 950 and The 300A may be positioned so as to overlap with the channel area of ​​the 300A. An example of this is shown in the diagram. This is shown in Figure 55. Figure 55 shows a stacked structure of transistor 950 and transistor 300A. This is a cross-sectional view in the channel length (L) direction of an example of such a case. The configuration shown in Figure 55 is... This allows for a further reduction in the area required to place the transistors.

[0548] Although not shown in the figures, transistor 950 and other transistors shown in Embodiments 2 and 3 are also included. Transistors (for example, transistors 100A to 100K, and transistors) A stacked structure of transistors (300A to 300G) may also be used.

[0549] Thus, the metal oxide film according to one aspect of the present invention allows for the stacking of transistors of various shapes. It can also be suitably used in structures.

[0550] This embodiment may be appropriately combined with other embodiments described herein, at least in part. They can be implemented in combination.

[0551] (Embodiment 5) In this embodiment, the display device having a transistor as illustrated in the previous embodiment An example will be explained below using Figures 56 to 63.

[0552] Figure 56 is a top view showing an example of a display device. The display device 700 shown in Figure 56 is the first A pixel section 702 provided on the substrate 701 and a source drive provided on the first substrate 701 The Pixel circuit section 704 and the gate driver circuit section 706, and the pixel section 702 and the source driver circuit A sealing material 712 is arranged to surround the path section 704 and the gate driver circuit section 706. It includes a second substrate 705 provided opposite the first substrate 701. The first substrate 701 and the second substrate 705 are sealed by a sealing material 712. The pixel section 702, the source driver circuit section 704, and the gate driver circuit section 706 are It is sealed by the first substrate 701, the sealing material 712, and the second substrate 705. Although not shown in Figure 56, a display element is provided between the first substrate 701 and the second substrate 705. It gets kicked.

[0553] Furthermore, the display device 700 is surrounded by a sealing material 712 on the first substrate 701. In a region different from the region, there is a pixel section 702, a source driver circuit section 704, and a gate driver circuit. FPC terminals electrically connected to the path section 706 and the gate driver circuit section 706, respectively. A sub-unit 708 (FPC: Flexible printed circuit) is provided. Furthermore, FPC716 is connected to FPC terminal 708, and FPC716 controls the drawing. Various signals are sent to the element section 702, the source driver circuit section 704, and the gate driver circuit section 706. These are supplied. Also, the pixel unit 702, source driver circuit unit 704, gate driver circuit Signal lines 710 are connected to the path section 706 and the FPC terminal section 708, respectively. The various signals supplied by 716 are transmitted via the signal line 710 to the pixel unit 702 and sourced Provided to the driver circuit section 704, the gate driver circuit section 706, and the FPC terminal section 708 ru.

[0554] Furthermore, the display device 700 may be provided with multiple gate driver circuit units 706. The device 700 includes a source driver circuit section 704 and a gate driver circuit section 706. Although an example is shown in which the pixel portion 702 is formed on the same first substrate 701, this configuration is not limited to this example. It is not necessary. For example, the gate driver circuit section 706 may be formed on the first substrate 701. Alternatively, only the source driver circuit section 704 may be formed on the first substrate 701. In this case, a substrate on which a source driver circuit or gate driver circuit, etc., is formed (for example, a single-wired board) A drive circuit substrate (formed from a crystalline semiconductor film or a polycrystalline semiconductor film) is formed on the first substrate 701. This configuration is also acceptable. Furthermore, the method of connecting the separately formed drive circuit board is not particularly limited. Instead, methods such as COG (Chip On Glass) and wire bonding are used. You can use it.

[0555] Furthermore, the display device 700 includes a pixel section 702, a source driver circuit section 704, and a gate The driver circuit section 706 has multiple transistors.

[0556] Furthermore, the display device 700 can have various elements. An example of such elements is: For example, electroluminescent (EL) elements (EL elements including organic and inorganic materials, (Electroluminescent elements, inorganic EL elements, LEDs, etc.), light-emitting transistor elements (which emit light according to current) Transistors, electron emission elements, liquid crystal elements, electron ink elements, electrophoretic elements, electro Lowwetting element, plasma display panel (PDP), MEMS (micro-electromechanical systems) Electro-mechanical systems) displays (e.g., grating light bulbs) GLV (Global Micromirror Device), Digital Micromirror Device (DMD), Digital Micro-Shatter DMS (Dynamic Modulation System) element, Interferometric Modulation (IMOD) element Examples include piezoelectric ceramic displays.

[0557] Another example of a display device using EL elements is an EL display. An example of a display device using emission elements is a field emission display (FE D) or SED type flat display (SED: Surface-conductivity Examples include (n Electron-emitter Display), which uses liquid crystal elements. Examples of such display devices include liquid crystal displays (transmissive liquid crystal displays, semi-transmissive liquid crystal displays). Display, reflective liquid crystal display, direct-view liquid crystal display, projection liquid crystal display Examples include (Ray). An example of a display device using an electronic ink element or electrophoretic element is: Examples include electronic paper. Furthermore, there are semi-transmissive liquid crystal displays and reflective liquid crystal displays. If implemented, some or all of the pixel electrodes would function as reflective electrodes. This is how it should be done. For example, some or all of the pixel electrodes could be made of aluminum, silver, etc. It would be good to have it. Furthermore, in that case, a memory circuit such as SRAM should be placed below the reflective electrode. It is also possible to implement this feature. This will further reduce power consumption.

[0558] The display method used in the display device 700 is either progressive or interlaced. These can be used. Also, when displaying in color, the color elements controlled by pixels include R It is not limited to the three colors GB (R stands for red, G for green, and B for blue). For example, if the pixels have R and G It may consist of four pixels: a pixel, a B pixel, and a W (white) pixel. Alternatively, a pentile arrangement. As shown in the column, two of the RGB colors make up one color element, and each color element produces two different colors. You may also select and configure this option. Alternatively, you can add one or more colors to RGB, such as yellow, cyan, magenta, etc. Additional elements may be added. Note that the size of the display area for each color element dot may differ. However, the disclosed invention is not limited to a color display device, but also includes a monochrome display device. It can also be applied to the display device shown.

[0559] In addition, the backlight (organic EL elements, inorganic EL elements, LEDs, fluorescent lamps, etc.) emits white light. (W) is used to enable the display device to display in full color, and the coloring layer (also called a color filter) You may also use ( ). The colored layer may be, for example, red (R), green (G), blue (B ), yellow (Y), etc. can be used in appropriate combinations. By using a colored layer This allows for higher color reproduction compared to cases where a colored layer is not used. By arranging a region having a colored layer and a region without a colored layer, a region without a colored layer is created. White light in the area may be used directly for display. A portion of the area may be placed without a colored layer. By placing it in this position, the reduction in brightness caused by the colored layer during bright displays can be minimized, and power consumption is reduced by 2 In some cases, the emission can be reduced by 10% to 30%. However, this is due to the spontaneous generation of organic EL elements and inorganic EL elements. When using optical elements for full-color display, R, G, B, Y, and W are used, each with its own emitted color. It is also acceptable to emit light from the element. By using a self-luminescent element, it is possible to achieve better results than when using a colored layer. Furthermore, it may be possible to reduce power consumption even further.

[0560] Furthermore, the colorization method involves passing a portion of the light emitted from the white light source through a color filter. In addition to the method of converting to red, green, and blue (color filter method), red, green, blue A method that uses each color of light emission separately (three-color method), or a method that uses red or a portion of the light emitted from blue light emission. A method for converting to green (color conversion method, quantum dot method) may also be applied.

[0561] In this embodiment, regarding the configuration in which liquid crystal elements and EL elements are used as display elements: This will be explained using Figures 57 to 59. Note that Figures 57 and 58 are based on the single-point chain shown in Figure 56. This is a cross-sectional view of a line QR, and it is configured using liquid crystal elements as display elements. Figure 59 is a cross-sectional view of the dashed line QR shown in Figure 56, and an EL element is used as the display element. This is the configuration used.

[0562] First, I will explain the common parts shown in Figures 57 to 59, and then I will explain the different parts. I will explain below.

[0563] [Explanation of common parts of display devices] The display device 700 shown in Figures 57 to 59 includes a wiring section 711 and a pixel section 702. It has a source driver circuit section 704 and an FPC terminal section 708. The line section 711 has a signal line 710. The pixel section 702 has a transistor 750 and It has a capacitive element 790. The source driver circuit section 704 also has a transistor 752. To possess.

[0564] Transistors 750 and 752 are similar to transistor 100B shown above. This is the configuration. Note that the configurations of transistors 750 and 752 are described previously. Other transistors shown in the embodiment may also be used.

[0565] The transistor used in this embodiment is made of an oxide that has been purified to suppress the formation of oxygen vacancies. It has a semiconductor film. The transistor can reduce the off-current. Therefore, the image The holding time of electrical signals such as signals can be extended, and the writing interval is also extended when the power is on. It can be set to a certain value. Therefore, the frequency of refresh operations can be reduced, thus reducing power consumption. It has the effect of suppressing force.

[0566] Furthermore, the transistor used in this embodiment is capable of obtaining a relatively high field-effect mobility. Therefore, high-speed operation is possible. For example, a transistor capable of such high-speed operation can be used in a liquid crystal display. By using it in a display device, the switching transistors in the pixel section and the drive circuit section are used. Driver transistors can be formed on the same substrate. That is, they can be used as a separate drive circuit. Therefore, since there is no need to use semiconductor devices formed from silicon wafers, etc., This reduces the number of parts. In addition, the pixel section also has a transistor that can be driven at high speed. By using ZISTA, high-quality images can be provided.

[0567] Capacitive element 790 has a conductive film that functions with the first gate electrode of transistor 750. The lower electrode is formed through a process of processing the same conductive film, and the transistor 750 has The process involves fabricating a conductive film identical to the conductive film that functions as both the source electrode and the drain electrode. It has an upper electrode that is formed, and a transistor between the lower electrode and the upper electrode. A process of forming an insulating film identical to the insulating film that functions as the first gate insulating film of 750. The insulating film formed through this process, and the insulating film that functions as a protective insulating film for transistor 750, An insulating film is provided, which is formed through a process of forming an insulating film. That is, a capacitive element 790 has a multilayer structure in which an insulating film, which functions as a dielectric film, is sandwiched between a pair of electrodes. ru.

[0568] Furthermore, in Figures 57 to 59, transistor 750, transistor 752, and A planarizing insulating film 770 is provided on the quantitative element 790.

[0569] Furthermore, in Figures 57 to 59, the transistor 750 of the pixel unit 702 and - The transistor 752 in the driver circuit section 704 and a transistor with the same structure While examples of configurations have been given, the system is not limited to these. For example, a pixel unit 702 and a source Different transistors may be used for the driver circuit section 704. Specifically, the pixel section 7 A top-gate transistor is used in 02, and a bottom-gate transistor is used in the source driver circuit section 704. A configuration using a T-type transistor, or a bottom-gate type transistor in the pixel section 702 The configuration uses a top-gate type transistor in the source driver circuit section 704. These are some examples. Furthermore, the source driver circuit section 704 described above is combined with the gate driver circuit section. You may interpret it differently.

[0570] Furthermore, signal line 710 is connected to the source and drain electrodes of transistors 750 and 752. It is formed through the same process as a conductive film that functions as a signal line 710, for example, a copper element When using materials containing [specific material], signal delays caused by wiring resistance are reduced, and large-screen displays are possible. It becomes Noh.

[0571] Furthermore, the FPC terminal section 708 includes a connecting electrode 760, an anisotropic conductive film 780, and FPC 71 It has 6. The connecting electrode 760 is the source electrode of transistors 750 and 752 and It is formed through the same process as the conductive film that functions as a rain electrode. Also, the connecting electrode 760 is The terminals of the FPC716 are electrically connected via the anisotropic conductive film 780.

[0572] Furthermore, for example, glass substrates can be used as the first substrate 701 and the second substrate 705. This is possible. Also, the first substrate 701 and the second substrate 705 are flexible substrates. A flexible substrate may be used. Examples of such flexible substrates include plastic substrates. ru.

[0573] Furthermore, a structure 778 is provided between the first substrate 701 and the second substrate 705. The fabricated body 778 is a columnar spacer obtained by selectively etching an insulating film. It is provided to control the distance (cell gap) between the first substrate 701 and the second substrate 705. It is possible to use a spherical spacer as the structure 778.

[0574] Furthermore, the second substrate 705 side has a light-shielding film 738 that functions as a black matrix, A colored film 736 that functions as a color filter, and a light-shielding film 738 and a film in contact with the colored film 736 An insulating film 734 is provided.

[0575] [Example configuration of a display device using liquid crystal elements] The display device 700 shown in Figure 57 has a liquid crystal element 775. The liquid crystal element 775 is a conductive film It has 772, a conductive film 774, and a liquid crystal layer 776. The conductive film 774 is on the second substrate 705 It is provided on the side and functions as a counter electrode. The display device 700 shown in Figure 57 is a conductive film The orientation state of the liquid crystal layer 776 changes depending on the voltage applied to 772 and the conductive film 774. By controlling the transmission and opacity of light, an image can be displayed.

[0576] Furthermore, the conductive film 772 serves as the source electrode and drain electrode of the transistor 750. It is electrically connected to a conductive film that functions as a conductive film. The conductive film 772 is formed on the planar insulating film 770. It then functions as a pixel electrode, that is, one of the electrodes of the display element.

[0577] The conductive film 772 is a conductive film that is transparent in visible light, or a conductive film that is transparent in visible light. A conductive film with light-transmitting properties can be used. Examples of conductive films that are transparent in visible light include: For example, a material containing one element selected from indium (In), zinc (Zn), and tin (Sn). It is advisable to use a material. Examples of conductive films that are reflective in visible light include aluminum. Alternatively, materials containing silver may be used.

[0578] When a conductive film that is reflective in visible light is used for the conductive film 772, the display device 700 is: It will be a reflective liquid crystal display device. In addition, the conductive film 772 is a conductive film that is transparent in visible light. When using this method, the display device 700 becomes a transmissive liquid crystal display device.

[0579] Furthermore, by changing the configuration on the conductive film 772, the driving method of the liquid crystal element can be changed. An example of this case is shown in Figure 58. Also, the display device 700 shown in Figure 58 is a liquid crystal element This is an example of a configuration using a transverse electric field method (e.g., FFS mode) as the driving method. Figure 58 In the configuration shown, an insulating film 773 is provided on the conductive film 772, and a conductive film is provided on the insulating film 773. A 774 is provided. In this case, the conductive film 774 is a common electrode. It has the function of generating electricity between the conductive film 772 and the conductive film 774 via the insulating film 773. The orientation state of the liquid crystal layer 776 can be controlled by the boundary.

[0580] Also, although not shown in Figures 57 and 58, conductive film 772 or conductive film 774 The configuration includes providing an alignment film on one or both sides of the offset, on the side that is in contact with the liquid crystal layer 776. It is also possible to use polarizing members, phase difference members, and reflectors, although these are not shown in Figures 57 and 58. Optical components (optical substrates) such as protective members may be provided as appropriate. For example, polarizing substrates and position Circular polarization using a phase-difference substrate may also be used. Furthermore, backlights and sidelights may be used as light sources. You may use any of these.

[0581] When using liquid crystal elements as display elements, thermotropic liquid crystals, low molecular weight liquid crystals, and polymer liquid crystals are used. Crystals, polymer-dispersed liquid crystals, ferroelectric liquid crystals, antiferroelectric liquid crystals, etc. can be used. Depending on the conditions, the liquid crystal material can be classified into cholesteric phase, smectic phase, cubic phase, and chi. It exhibits the ranematic phase, isotropic phase, etc.

[0582] Furthermore, when employing a transverse electric field method, it is also possible to use a liquid crystal that exhibits a blue phase without using an alignment layer. The blue phase is one of the liquid crystal phases, and as the temperature of cholesteric liquid crystal is increased, the cholesteric phase This phase appears just before the transition from the blue phase to the isotropic phase. The blue phase only appears within a narrow temperature range. To improve the temperature range, a liquid crystal assembly containing several weight percent or more of chiral agent was mixed in. The resulting material is used in the liquid crystal layer. The liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent provides a fast response. Because the degree of polarization is short and the optical properties are isotropic, orientation treatment is unnecessary. Furthermore, an orientation film is not required. Therefore, rubbing is unnecessary, thus eliminating the electrostatic discharge damage caused by rubbing. This can prevent defects and reduce damage to liquid crystal displays during the manufacturing process. Furthermore, liquid crystal materials exhibiting a blue phase have low dependence on viewing angle.

[0583] Furthermore, when using liquid crystal elements as display elements, TN (Twisted Nematic) ) mode, IPS (In-Plane-Switching) mode, FFS (Frin (Field Switching) mode, ASM (Axially Symmetry) tric aligned Micro-cell) mode, OCB(Optical Compensated Birefringence mode, FLC (Ferroe) lectric Liquid Crystal) mode, AFLC (AntiFerr Features such as the (electric Liquid Crystal) mode can be used. .

[0584] Furthermore, a normally black type liquid crystal display device, for example, one that employs vertical alignment (VA) mode, It may also be used as a transmissive liquid crystal display device. Several vertical orientation modes can be listed. For example, MVA (Multi-Domain Vertical Alignment) ) Mode, PVA (Patterned Vertical Alignment) Mode You can use modes such as ASV mode.

[0585] [Display devices that use light-emitting elements] The display device 700 shown in Figure 59 has a light-emitting element 782. The light-emitting element 782 is made of a conductive film It has 772, an EL layer 786, and a conductive film 788. The display device 700 shown in Figure 59 is The EL layer 786 of the optical element 782 emits light, allowing an image to be displayed. Furthermore, the EL layer 786 contains organic compounds or inorganic compounds such as quantum dots.

[0586] Examples of materials that can be used with organic compounds include fluorescent materials or phosphorescent materials. It can be made. Also, as a material that can be used for quantum dots, colloidal quantum dots Materials, alloy-type quantum dot materials, core-shell type quantum dot materials, core-type quantum dot materials, These are some examples. Also, the origins of groups 12 and 16, 13 and 15, or 14 and 16. Materials containing elementary groups may be used. Alternatively, cadmium (Cd), selenium (Se), Zinc (Zn), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (P) b) Quantum having elements such as gallium (Ga), arsenic (As), and aluminum (Al). Dot material may also be used.

[0587] Furthermore, the above-mentioned organic and inorganic compounds include, for example, those produced by vapor deposition (including vacuum deposition). Methods such as droplet ejection (also called inkjet method), coating method, and gravure printing are used. It can be formed by using low molecular weight materials, medium molecular weight materials (O It may also contain ligomers, dendrimers, or polymeric materials.

[0588] Here, we will explain the method for forming the EL layer 786 using the droplet ejection method, with reference to Figure 60. To clarify, Figures 60(A) to 60(D) are cross-sectional views illustrating the method for fabricating the EL layer 786. be.

[0589] First, a conductive film 772 is formed on the planar insulating film 770, and a part of the conductive film 772 is covered. A thin insulating film 730 is formed (see Figure 60(A)).

[0590] Next, liquid droplets from the droplet dispensing device 783 are dispensed onto the exposed portion of the conductive film 772, which is an opening in the insulating film 730. A droplet 784 is dispensed to form a layer 785 containing the composition. The droplet 784 is a composition containing a solvent. It adheres to the conductive film 772 (see Figure 60(B)).

[0591] The process of dispensing the droplet 784 may also be carried out under reduced pressure.

[0592] Next, the solvent is removed from the layer 785 containing the composition and solidified to form the EL layer 786. Form (see Figure 60(C)).

[0593] The solvent can be removed by either a drying or heating process.

[0594] Next, a conductive film 788 is formed on the EL layer 786 to form a light-emitting element 782 (Figure 60( See D).

[0595] By performing the EL layer 786 using the droplet ejection method, the composition can be selectively ejected. Therefore, material waste can be reduced. Also, lithography for processing shapes Because no additional steps are required, the process can be simplified, resulting in lower costs.

[0596] The droplet dispensing method described above refers to a nozzle having a dispensing port for the composition, or one or This term refers to a general category of devices that have means for discharging droplets, such as heads with multiple nozzles.

[0597] Next, the droplet dispensing device used in the droplet dispensing method will be explained using Figure 61. This is a conceptual diagram illustrating the droplet dispensing device 1400.

[0598] The droplet dispensing device 1400 has a droplet dispensing means 1403. Unit 3 has head 1405 and head 1412.

[0599] Heads 1405 and 1412 are connected to control means 1407, which is a computer By controlling it with the -1410, it is possible to draw on a pre-programmed pattern. can.

[0600] Furthermore, as for the timing of drawing, for example, the marker 1 formed on the substrate 1402 You can use 411 as the reference point. Alternatively, you can determine the reference point by using the outer edge of substrate 1402 as the reference point. It is also acceptable to do so. Here, marker 1411 is detected by imaging means 1404, and image processing means 1 The signal converted to digital in 409 is recognized by computer 1410 and a control signal is issued. It is then sent to the control unit 1407.

[0601] The imaging means 1404 may include a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CM). Image sensors using an OS can be used. The information of the pattern to be performed is stored in the storage medium 1408, and based on this information Then, a control signal is sent to the control means 1407, and the individual heads 140 of the droplet dispensing means 1403 5. The heads 1412 can be controlled individually. The material to be dispensed is supplied by the material supply source 141 3. Material is supplied from the material source 1414 to heads 1405 and 1412 respectively via piping. To be given.

[0602] The inside of head 1405 is a space for filling with liquid material, as indicated by the dotted line 1406, and discharge It has a structure that includes a nozzle, which is the outlet. Although not shown in the diagram, head 1412 is also head 1 It has a similar internal structure to the 405. The nozzles of head 1405 and head 1412 are different. By setting up the size, it is possible to draw different materials at different widths simultaneously with a single head. It can extrude and draw with multiple types of luminescent materials, and when drawing over a wide area... To improve throughput, the same material is simultaneously dispensed from multiple nozzles for drawing. This is possible. When using a large substrate, heads 1405 and 1412 move across the substrate as shown in Figure 6. 1. Freely scan in the direction of the X, Y, and Z arrows shown in the image, and freely set the area to be drawn. This allows for the drawing of multiple identical patterns on a single circuit board.

[0603] Furthermore, the process of dispensing the composition may be carried out under reduced pressure. The substrate is heated during dispensing. This may also be done. After the composition is extruded, one or both of the following steps are performed: drying and / or calcination. Drying and calcination steps Both processes involve heat treatment, but their purpose, temperature, and time differ. The drying and firing processes are carried out under normal pressure or reduced pressure using laser irradiation, instantaneous heat annealing, or heating. This is done using a furnace or similar device. The timing and number of times this heat treatment is performed are not particularly limited. It is not possible. In order to carry out the drying and firing processes properly, the temperature at that time depends on the material of the substrate and the assembly. It depends on the properties of the finished product.

[0604] As described above, the EL layer 786 can be fabricated using a droplet ejection device.

[0605] Let's return to the explanation of the display device 700 shown in Figure 59.

[0606] Furthermore, the display device 700 shown in Figure 59 has an insulating film 770 and a conductive film 772 on which an insulating film is applied. A border film 730 is provided. The insulating film 730 covers a portion of the conductive film 772. 782 is a top emission structure. Therefore, the conductive film 788 is translucent, E It transmits the light emitted by the L layer 786. In this embodiment, top emission The structure is illustrated as an example, but is not limited to this. For example, light is emitted from the conductive film 772 side. The bottom emission structure and the dual emission of light to both conductive film 772 and conductive film 788 It can also be applied to luminous emission structures.

[0607] Furthermore, a colored film 736 is provided in a position that overlaps with the light-emitting element 782, and overlaps with the insulating film 730. A light-shielding film 738 is provided at the location, the routing wiring section 711, and the source driver circuit section 704. Furthermore, the colored film 736 and the light-shielding film 738 are covered with an insulating film 734. Furthermore, the space between the light-emitting element 782 and the insulating film 734 is filled with a sealing film 732. (See Figure 59) In the display device 700 shown, an example was given of a configuration in which a colored film 736 is provided, It is not limited to this. For example, when the EL layer 786 is formed by coloring, A configuration without the film 736 is also possible.

[0608] [Example configuration of a display device with input / output devices] Furthermore, an input / output device may be provided to the display device 700 shown in Figures 58 and 59. Examples of power devices include touch panels.

[0609] The configuration in which a touch panel 791 is provided on the display device 700 shown in Figure 58 is shown in Figures 62 and 59. Figure 63 shows the configurations in which a touch panel 791 is provided on the display device 700.

[0610] Figure 62 is a cross-sectional view of a configuration in which a touch panel 791 is provided to the display device 700 shown in Figure 58. Figure 63 is a cross-sectional view of a configuration in which a touch panel 791 is provided to the display device 700 shown in Figure 59. be.

[0611] First, the touch panel 791 shown in Figures 62 and 63 will be explained below.

[0612] The touch panel 791 shown in Figures 62 and 63 is provided between the substrate 705 and the colored film 736. It is a so-called in-cell type touch panel. The touch panel 791 has a light-shielding film 738 The colored film 736 may be formed on the substrate 705 side before the colored film 705 is formed.

[0613] The touch panel 791 consists of a light-shielding film 738, an insulating film 792, an electrode 793, and an electrode. It has 794, an insulating film 795, an electrode 796, and an insulating film 797. For example, a finger or When a detected object such as a tyrus comes into close proximity, the mutual capacitance between electrode 793 and electrode 794 changes. It can detect transformation.

[0614] Furthermore, above the transistor 750 shown in Figures 62 and 63, there is an electrode 793 and The intersection with electrode 794 is clearly indicated. Electrode 796 is an opening provided in the insulating film 795. Through this, electrode 794 is electrically connected to the two electrodes 793 that sandwich it. (See Figure 62) Figure 63 illustrates a configuration in which the region where the electrode 796 is provided is located in the pixel section 702. However, it is not limited to this, and for example, it may be formed in the source driver circuit section 704.

[0615] Electrodes 793 and 794 are provided in the region overlapping with the light-shielding film 738. Also, see Figure 62. As shown, it is preferable that the electrode 793 is provided so as not to overlap with the light-emitting element 782. Furthermore, as shown in Figure 63, the electrode 793 is provided so as not to overlap with the liquid crystal element 775. It is preferable that the electrode 793 overlaps with the light-emitting element 782 and the liquid crystal element 775. It has an opening in the region. That is, the electrode 793 has a mesh shape. By doing so, the electrode 793 is configured not to block the light emitted by the light-emitting element 782. This is possible. Alternatively, the electrode 793 can be configured not to block the light transmitted through the liquid crystal element 775. This is possible. Therefore, the reduction in brightness due to the placement of the touch panel 791 is extremely small. Because it is small, it is possible to realize a display device that has high visibility and reduced power consumption. The Extreme 794 should have a similar configuration.

[0616] Furthermore, since electrodes 793 and 794 do not overlap with the light-emitting element 782, electrodes 793 and A metal material with low visible light transmittance can be used for electrode 794. Alternatively, electrode 7 Since electrode 93 and electrode 794 do not overlap with liquid crystal element 775, electrodes 793 and 794 This allows the use of metal materials with low visible light transmittance.

[0617] Therefore, compared to electrodes using oxide materials with high visible light transmittance, electrode 793 and This makes it possible to lower the resistance of electrode 794, improving the sensor sensitivity of the touch panel. It is possible.

[0618] For example, conductive nanowires may be used for electrodes 793, 794, and 796. The nanowires have an average diameter of 1 nm to 100 nm, preferably 5 nm to 50 nm. The size should be less than or equal to m, more preferably between 5 nm and 25 nm. The wires include metal nanowires such as Ag nanowires, Cu nanowires, or Al nanowires. A wire or carbon nanotube can be used. For example, electrodes 664, 6 When using Ag nanowires for either 65 or 667, or all of them, in visible light The light transmittance must be 89% or higher, and the sheet resistance must be between 40Ω / □ and 100Ω / □. can.

[0619] Furthermore, Figures 62 and 63 illustrate the configuration of an in-cell type touch panel. However, it is not limited to this. For example, a so-called on-cell type tactile paving formed on the display device 700 A so-called out-cell type touch panel, used by being attached to a touch panel or display device 700. That is also acceptable.

[0620] Thus, the display device according to one aspect of the present invention can be combined with various forms of touch panels. It can be used.

[0621] This embodiment may be appropriately combined with other embodiments described herein, at least in part. They can be implemented in combination.

[0622] (Embodiment 6) This embodiment describes an example of a semiconductor device according to one aspect of the present invention. Transistors are suitable for miniaturization.

[0623] Figure 64 shows an example of transistor 200. Figure 64(A) shows transistor 200 The top view is shown. Note that some of the film has been omitted in Figure 64(A) for clarity. Furthermore, Figure 64(B) is a cross-sectional view corresponding to the dashed line X1-X2 shown in Figure 64(A). Figure 64(C) is a cross-sectional view corresponding to Y1-Y2.

[0624] Transistor 200 has a conductor 205 (conductor 205a, o) that functions as the gate electrode. and conductor 205b), and conductor 260 (conductors 260a and conductor 260b) Insulators 220, 222, 224, and insulating layer function as gate insulating layers. Body 250 and oxide semiconductor 230 (oxide semiconductor 23) having a region where a channel is formed 0a, oxide semiconductor 230b, and oxide semiconductor 230c), and source or drain A conductor 240a that functions as one of the two, and a conductor that functions as the other of the source or drain. It comprises an electrical element 240b and an insulator 280 having excess oxygen.

[0625] Furthermore, the oxide semiconductor 230 consists of an oxide semiconductor 230a and an acid on the oxide semiconductor 230a. It comprises an oxide semiconductor 230b and an oxide semiconductor 230c on the oxide semiconductor 230b. When transistor 200 is turned on, current flows mainly through the oxide semiconductor 230b. (A channel is formed). On the other hand, oxide semiconductor 230a and oxide semiconductor 230c In the vicinity of the interface with the oxide semiconductor 230b (which may be a mixed region), current flows. While it may be possible for other areas to function as an insulator, other areas may function as an insulator.

[0626] The structure shown in Figure 64 has a conductor 260 that functions as a gate electrode, and a conductor 260a, It is a laminated structure having a conductor 260b. Also, a conductor 2 that functions as a gate electrode An insulator 270 is provided on 60.

[0627] Conductor 205 is molybdenum, titanium, tantalum, tungsten, aluminum, copper, A metal film containing elements selected from chromium, neodymium, and scandium, or the above elements The components include metal nitride films (titanium nitride film, molybdenum nitride film, tungsten nitride film), etc. Yes. Or, indium oxide containing indium tin oxide, tungsten oxide, tungsten oxide, tungsten oxide. Indium zinc oxide containing gusten, indium oxide containing titanium oxide, titanium oxide Indium tin oxide containing indium zinc oxide, indium tin oxide with added silicon dioxide Conductive materials such as oxides can also be applied.

[0628] For example, as the conductor 205a, a conductor having barrier properties against hydrogen, nitride It is preferable to use a material such as a conductor and laminate highly conductive tungsten as the conductive material 205b. By using this combination, the oxide semiconductor 23 maintains its conductivity as a wiring. The diffusion of hydrogen into 0 can be suppressed. Note that in Figure 64, the conductor 205a and Although a two-layer structure of conductor 205b is shown, the configuration is not limited to this, and can be a single layer or a stack of three or more layers. Structure is also acceptable.

[0629] Insulators 220 and 224 are silicon oxide films and silicon oxide nitride films, It is preferable that the insulator contains oxygen. In particular, it is preferable that the insulator 224 contains excess oxygen ( It is preferable to use an insulator that contains an excess of oxygen compared to the stoichiometric composition. By providing an oxygen-containing insulator in contact with the oxide constituting the transistor 200, This can compensate for oxygen deficiencies in the oxide. Note that insulator 220 and insulator 224 are, It is not necessary to use the same materials for formation.

[0630] The insulator 222 is, for example, silicon oxide, silicon oxide nitride, silicon oxide nitride, oxide Aluminum, hafnium oxide, tantalum oxide, zirconium oxide, zirconate titanate Lead (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 Using insulators containing so-called high-k materials such as (BST) in a single layer or multilayer configuration. These are preferable. Alternatively, these insulators may be, for example, aluminum oxide, bismuth oxide, or gel oxide. Manium, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide Zirconium oxide may be added. Alternatively, these insulators may be nitrided. Even if silicon oxide, silicon oxide nitride, or silicon nitride is laminated onto the above insulator, good.

[0631] The insulator 222 may have a laminated structure of two or more layers. In that case, the same material may be used. The laminated structure is not limited to that made up of the same material, but may also be a laminated structure made up of different materials.

[0632] The insulator 220 and the insulator 224 have an insulator 222 containing a high-k material. This allows the insulator 222 to capture electrons under specific conditions, thereby increasing the threshold voltage. In other words, the insulator 222 can become negatively charged.

[0633] For example, silicon oxide is used for insulators 220 and 224, and insulator 222 Materials with many electron trapping levels, such as hafnium oxide, aluminum oxide, and tantalum oxide. If used, temperatures higher than the operating temperature or storage temperature of the semiconductor device (for example, 125°C) may occur. Under temperatures between 450°C and 150°C (typically between 150°C and 300°C), the electrical current of the conductor 205 Maintaining a voltage higher than the potential of the source or drain electrode for 10 milliseconds or more, typically 1 minute. By maintaining the above, the oxide constituting the transistor 200 moves toward the conductor 205. Electrons move. At this time, some of the moving electrons are trapped in the electron trapping levels of the insulator 222. It will be done.

[0634] A transistor that has captured the necessary amount of electrons at the electron trapping level of insulator 222 reaches the threshold level. The voltage shifts to the positive side. Furthermore, electron capture is controlled by controlling the voltage of conductor 205. The quantity can be controlled, and consequently, the threshold voltage can be controlled. By having this feature, transistor 200 remains in a non-conductive state (off) even when the gate voltage is 0V. This is a normally-off type transistor (also called a "state").

[0635] Furthermore, the electron capture process can be carried out during the transistor fabrication process. For example, After the formation of a conductor connected to the source conductor or drain conductor of the lampistor, After the completion of the preceding process (wafer processing), or after the wafer dicing process, packaging This should be done at some stage, either later or before the product leaves the factory.

[0636] Furthermore, by appropriately adjusting the film thickness of insulators 220, 222, and 224, It is possible to control the voltage value. Alternatively, a transistor with low leakage current when not conducting. It can provide a transistor with stable electrical characteristics. This is possible. Or, it is possible to provide a transistor with a large on-current. Or, It is possible to provide transistors with small threshold swing values. Or, We can provide highly reliable transistors.

[0637] Oxide semiconductor 230a, oxide semiconductor 230b, and oxide semiconductor 230c are In - It is formed from metal oxides such as M-Zn oxide (where M is Al, Ga, Y, or Sn). Furthermore, In-Ga oxide and In-Zn oxide may be used as the oxide semiconductor 230.

[0638] The insulator 250 is, for example, silicon oxide, silicon oxide nitride, silicon oxide nitride, oxide Aluminum, hafnium oxide, tantalum oxide, zirconium oxide, zirconate titanate Lead (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 Using insulators containing so-called high-k materials such as (BST) in a single layer or multilayer configuration. This can be done. Or, for example, aluminum oxide, bismuth oxide, germanium oxide can be used as an insulator. Nium, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide Zirconium oxide may be added. Alternatively, these insulators may be nitrided. The insulator may be used with silicon oxide, silicon oxide nitride, or silicon nitride laminated on top of it. stomach.

[0639] Furthermore, as insulator 250, similar to insulator 224, it is more than oxygen that satisfies the stoichiometric composition. It is preferable to use an oxide insulator that contains a large amount of oxygen. By providing the edge body in contact with the oxide semiconductor 230, oxygen vacancies in the oxide semiconductor 230 are created. This can be reduced.

[0640] Furthermore, the insulator 250 is made of aluminum oxide, aluminum oxide nitride, gallium oxide, and acid Gallium nitride, yttrium oxide, yttrium oxide nitride, hafnium oxide, oxide nitride Using insulating films that have barrier properties against oxygen and hydrogen, such as hafnium and silicon nitride. This can be achieved. When formed using such materials, oxygen is released from the oxide semiconductor 230. It functions as a layer that prevents contamination from external sources such as hydrogen.

[0641] Furthermore, the insulator 250 has the same product as insulators 220, 222, and 224. It may have a layered structure. The insulator 250 captures the amount of electrons necessary for the electron trapping level. By having an insulator, transistor 200 shifts the threshold voltage to the positive side. This is possible. With this configuration, transistor 200 has a gate voltage of 0V. However, it remains in a non-conductive state (also called the off state), making it a normally-off type transistor.

[0642] Furthermore, in the semiconductor device shown in Figure 64, between the oxide semiconductor 230 and the conductor 260, A barrier film may be provided in addition to the insulator 250. Alternatively, a barrier film may be provided on the oxide semiconductor 230c. You may use materials that have a specific property.

[0643] For example, an insulating film containing excess oxygen is provided in contact with the oxide semiconductor 230, and further a barrier film is provided. By encapsulating the oxide, it is brought into a state that closely matches the stoichiometric composition, or stoichiometric A supersaturated state can be created where there is more oxygen than the composition allows. Also, water in the oxide semiconductor 230 It can prevent the intrusion of impurities such as elements.

[0644] Conductors 240a and 240b, one of which functions as a source electrode and the other as It functions as a drain electrode.

[0645] Conductors 240a and 240b are aluminum, titanium, chromium, nickel, Copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten, etc. A metal or an alloy with this metal as the main component can be used. Also, in the figure, a single-layer structure is shown. As shown, a laminated structure of two or more layers is also acceptable.

[0646] For example, a titanium film and an aluminum film can be laminated. Alternatively, an aluminum film can be laminated on a tungsten film. A two-layer structure with stacked aluminum films, and a copper film stacked on top of a copper-magnesium-aluminum alloy film. Two-layer structure, two-layer structure with copper film laminated on titanium film, two-layer structure with copper film laminated on tungsten film It may also be a two-layer structure.

[0647] Furthermore, a titanium film or titanium nitride film, and a layer on top of the titanium film or titanium nitride film. A luminium film or copper film is laminated, and then a titanium film or titanium nitride film is formed on top of it. A three-layer structure, a molybdenum film or molybdenum nitride film, and the molybdenum film or molybdenum nitride film. An aluminum film or copper film is laminated on top of the butene film, and then a molybdenum film is laid on top of that. There are also three-layer structures that form a molybdenum nitride film. Furthermore, indium oxide, tin oxide, and A transparent conductive material containing zinc oxide may also be used.

[0648] Furthermore, the conductor 260 that functions as a gate electrode can be, for example, aluminum, chromium, A metal selected from copper, tantalum, titanium, molybdenum, and tungsten, or the gold mentioned above. It can be formed using an alloy composed of the aforementioned metals, or an alloy combining the aforementioned metals. Furthermore, using a metal selected from one or more of manganese and zirconium. This is also good. Furthermore, semiconductors represented by polycrystalline silicon doped with impurity elements such as phosphorus. Alternatively, silicides such as nickel silicide may be used.

[0649] For example, a two-layer structure in which a titanium film is laminated on an aluminum film is suitable. A two-layer structure in which a titanium film is laminated on a tungsten film, and a two-layer structure in which a tungsten film is laminated on a titanium nitride film. Layered structure, two-layer struct...

Claims

1. A display device having a first transistor, a second transistor, and a light-emitting element on a substrate, A first insulating layer having a region positioned above the channel formation region of the first transistor, An oxide semiconductor layer having a region disposed above the first insulating layer, A second insulating layer having a region disposed above the oxide semiconductor layer, A first conductive layer having a region located below the first insulating layer, A second conductive layer having a region positioned above the second insulating layer, A third conductive layer having a region positioned above the second insulating layer, The first conductive layer is electrically connected to the source or drain of the first transistor. The second conductive layer is electrically connected to either the source or the drain of the second transistor through a first opening provided in the second insulating layer. The third conductive layer is electrically connected to the other of the source or drain of the second transistor through a second opening provided in the second insulating layer. The oxide semiconductor layer has a first region, a second region, and a third region. The second region has a channel formation region for the second transistor, The first region has a fourth region in contact with the second conductive layer, The third region has a fifth region in contact with the third conductive layer, The region of the upper surface of the fourth region that has the highest height from the upper surface of the substrate is higher in height from the upper surface of the substrate than the region of the upper surface of the fifth region that has the highest height from the upper surface of the substrate. A display device wherein the first region overlaps with the first conductive layer.

2. A display device having a first transistor, a second transistor, and a light-emitting element on a substrate, A first insulating layer having a region positioned above the channel formation region of the first transistor, An oxide semiconductor layer having a region disposed above the first insulating layer, A second insulating layer having a region disposed above the oxide semiconductor layer, A first conductive layer having a region located below the first insulating layer, A second conductive layer having a region positioned above the second insulating layer, A third conductive layer having a region positioned above the second insulating layer, A third insulating layer having a region positioned above the second conductive layer and a region positioned above the third conductive layer, A fourth conductive layer having a region positioned above the third insulating layer, The first conductive layer is electrically connected to the source or drain of the first transistor. The second conductive layer is electrically connected to either the source or the drain of the second transistor through a first opening provided in the second insulating layer. The third conductive layer is electrically connected to the other of the source or drain of the second transistor through a second opening provided in the second insulating layer. The upper surface of the third insulating layer is flat. The fourth conductive layer has a region that functions as a pixel electrode of the light-emitting element, The oxide semiconductor layer has a first region, a second region, and a third region. The second region has a channel formation region for the second transistor, The first region has a fourth region in contact with the second conductive layer, The third region has a fifth region in contact with the third conductive layer, The region of the upper surface of the fourth region that has the highest height from the upper surface of the substrate is higher in height from the upper surface of the substrate than the region of the upper surface of the fifth region that has the highest height from the upper surface of the substrate. A display device wherein the first region overlaps with the first conductive layer.

3. A display device having a first transistor, a second transistor, and a light-emitting element on a substrate, A first insulating layer having a region positioned above the channel formation region of the first transistor, An oxide semiconductor layer having a region disposed above the first insulating layer, A second insulating layer having a region disposed above the oxide semiconductor layer, A first conductive layer having a region located below the first insulating layer, A second conductive layer having a region positioned above the second insulating layer, A third conductive layer having a region positioned above the second insulating layer, A third insulating layer having a region positioned above the second conductive layer and a region positioned above the third conductive layer, A fourth conductive layer having a region positioned above the third insulating layer, The first conductive layer is electrically connected to the source or drain of the first transistor. The second conductive layer is electrically connected to either the source or the drain of the second transistor through a first opening provided in the second insulating layer. The third conductive layer is electrically connected to the other of the source or drain of the second transistor through a second opening provided in the second insulating layer. The third insulating layer comprises an organic material, The fourth conductive layer has a region that functions as a pixel electrode of the light-emitting element, The oxide semiconductor layer has a first region, a second region, and a third region. The second region has a channel formation region for the second transistor, The first region has a fourth region in contact with the second conductive layer, The third region has a fifth region in contact with the third conductive layer, The region of the upper surface of the fourth region that has the highest height from the upper surface of the substrate is higher in height from the upper surface of the substrate than the region of the upper surface of the fifth region that has the highest height from the upper surface of the substrate. A display device wherein the first region overlaps with the first conductive layer.

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