Display device

Abstract

To provide a display device having a capacitive element with a high aperture ratio and capable of increasing the charge capacity. Also, to provide a display device having a capacitive element with a high transmittance in a pixel portion and capable of increasing the charge capacity. Further, to provide a display device with low power consumption. SOLUTION: A transistor having a first oxide semiconductor film in a channel formation region, a second oxide semiconductor film formed on the same surface as the first oxide semiconductor film, a pixel electrode electrically connected to the transistor, and a light-transmissive capacitive element in which a dielectric film is sandwiched between a pair of electrodes. One of the pair of electrodes is the second oxide semiconductor film, the other of the pair of electrodes is the pixel electrode, and the film thickness of the second oxide semiconductor film is thinner than the film thickness of the first oxide semiconductor film. 【SOLUTION】A transistor having a first oxide semiconductor film in a channel formation region, a second oxide semiconductor film formed on the same surface as the first oxide semiconductor film, a pixel electrode electrically connected to the transistor, and a light-transmissive capacitive element in which a dielectric film is sandwiched between a pair of electrodes. One of the pair of electrodes is the second oxide semiconductor film, the other of the pair of electrodes is the pixel electrode, and the film thickness of the second oxide semiconductor film is thinner than the film thickness of the first oxide semiconductor film. ​

Description

[Technical field]

[0001] The invention disclosed in this specification and elsewhere relates to a display device and an electronic device using the display device. [Background technology]

[0002] In recent years, flat panel displays such as liquid crystal displays (LCDs) have become widespread. In a display device such as a liquid crystal display, pixels arranged in the row and column directions The semiconductor device includes a transistor as a switching element and a liquid crystal display electrically connected to the transistor. A liquid crystal element and a capacitive element connected in parallel to the liquid crystal element are provided.

[0003] The semiconductor material constituting the semiconductor film of the above transistor is amorphous (non-crystalline) Silicon semiconductors such as silicon or polysilicon (polycrystalline) are widely used.

[0004] Metal oxides that exhibit semiconductor properties (hereinafter, referred to as oxide semiconductors) are used in transistors. It is a semiconductor material that can be applied to the semiconductor film of the following: zinc oxide or In-Ga-Zn system oxide Techniques for fabricating transistors using nitride semiconductors have been disclosed (Patent Document 1 and Patent Document 2). See patent document 2. ).

[0005] In order to increase the aperture ratio, a metal oxide film is provided on the same surface as the oxide semiconductor film of the transistor. The oxide semiconductor film and the pixel electrode connected to the transistor are provided at a predetermined distance from each other. A display device having such a capacitive element has been disclosed (see Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-123861 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-96055 [Patent Document 3] U.S. Patent No. 8,102,476 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] A capacitive element has a dielectric film provided between a pair of electrodes. Among the pair of electrodes, at least one of the electrodes is often formed of a conductive film having light-shielding properties such as a gate electrode, a source, or a drain constituting a transistor.

[0008] Also, the larger the capacitance value of the capacitive element, the longer the period during which the alignment of liquid crystal molecules in the liquid crystal element can be kept constant in the presence of an electric field. In a display device for displaying a still image, being able to lengthen this period can reduce the number of times of rewriting image data, and a reduction in power consumption can be expected.

[0009] Also, in order to increase the charge capacitance of the capacitive element, there is a means of increasing the occupied area of the capacitive element, specifically, increasing the area where a pair of electrodes overlap. However in the above display device, if the area of the conductive film having light-shielding properties is increased to increase the area where a pair of electrodes overlap, the aperture ratio of the pixel decreases, and the display quality of the image deteriorates.

[0010] For example, by forming the pair of electrodes from a material having light-transmitting properties, the charge capacitance of the capacitive element can be increased, and the aperture ratio of the pixel can be increased. However, when the transmittance of the above light-transmitting material is low, the amount of light from a light source such as a backlight needs to be increased ​​​​​​​ This would result in problems such as an increase in power consumption, and problems such as the capacitive element becoming colored, causing specific wavelength light to attenuate and the display quality of the image to deteriorate.

[0011] Therefore, in view of the above problems, one aspect of the present invention is to provide a display device having a capacitive element with a high aperture ratio and capable of increasing the charge capacity. Another aspect of the present invention is to provide a display device having a capacitive element with a high transmittance in the pixel portion and capable of increasing the charge capacity. Another aspect is to provide a display device with low power consumption. It should be noted that the description of these problems does not prevent the existence of other problems. It should be noted that one aspect of the present invention does not need to solve all of these problems. Other problems will naturally become clear from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other problems from the descriptions in the specification, drawings, claims, etc.

[0012] Note that the description of these problems does not prevent the existence of other problems. Note that one aspect of the present invention does not need to solve all of these problems. Other problems will naturally become clear from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other problems from the descriptions in the specification, drawings, claims, etc. drawings, claims, etc.

Means for Solving the Problems

[0013] One aspect of the present invention includes a transistor having a first oxide semiconductor film in a channel formation region, a second oxide semiconductor film formed on the same surface as the first oxide semiconductor film, a pixel electrode electrically connected to the transistor, and a transmissive capacitive element in which a dielectric film is sandwiched between a pair of electrodes. One of the pair of electrodes is the second oxide semiconductor film, the other of the pair of electrodes is the pixel electrode, and the thickness of the second oxide semiconductor film is thinner than the thickness of the first oxide semiconductor film. The display device is characterized by this. a second oxide semiconductor film formed on the same surface as the first oxide semiconductor film, and a pixel electrode electrically connected to the transistor, and a transmissive capacitive element in which a dielectric film is sandwiched between a pair of electrodes. One of the pair of electrodes is the second oxide semiconductor film, the other of the pair of electrodes is the pixel electrode, and the thickness of the second oxide semiconductor film is thinner than the thickness of the first oxide semiconductor film. The display device is characterized by this. a pixel electrode electrically connected to the transistor, and a transmissive capacitive element in which a dielectric film is sandwiched between a pair of electrodes. One of the pair of electrodes is the second oxide semiconductor film, the other of the pair of electrodes is the pixel electrode, and the thickness of the second oxide semiconductor film is thinner than the thickness of the first oxide semiconductor film. The display device is characterized by this. capacitive element in which a dielectric film is sandwiched between a pair of electrodes. One of the pair of electrodes is the second oxide semiconductor film, the other of the pair of electrodes is the pixel electrode, and the thickness of the second oxide semiconductor film is thinner than the thickness of the first oxide semiconductor film. The display device is characterized by this. One of the pair of electrodes is the second oxide semiconductor film, the other of the pair of electrodes is the pixel electrode, and the thickness of the second oxide semiconductor film is thinner than the thickness of the first oxide semiconductor film. The display device is characterized by this. The display device is characterized in that the thickness of the second oxide semiconductor film is thinner than the thickness of the first oxide semiconductor film.

[0014] Form the film thickness of the second oxide semiconductor film, which is one of the pair of electrodes of the capacitive element having translucency, to be thinner than the film thickness of the first oxide semiconductor film used for the channel formation region of the transistor. By doing so, the transmittance of the capacitive element can be improved. Therefore, a display device having a capacitive element with a high transmittance in the pixel portion and capable of increasing the charge capacity can be provided. Also, since the transistor can optimize the film thickness of the first oxide semiconductor film used for the channel formation region, a highly reliable display device can be obtained.

[0015] Another aspect of the present invention is a transistor having a first oxide semiconductor film in a channel formation region, a first oxide film formed on the first oxide semiconductor film, a second oxide semiconductor film formed on the same surface as the first oxide semiconductor film, a second oxide film formed on the second oxide semiconductor film, a pixel electrode electrically connected to the transistor, and a capacitive element having translucency with a dielectric film sandwiched between a pair of electrodes. One of the pair of electrodes is the second oxide semiconductor film and the second oxide film, the other of the pair of electrodes is the pixel electrode, and the film thickness of the second oxide film is thinner than the film thickness of the first oxide film.

[0016]

[0017] Form the film thickness of the second oxide film, which is a part of one of the pair of electrodes of the capacitive element having translucency, to be thinner than the film thickness of the first oxide film used for a part of the channel formation region of the transistor. By doing so, the transmittance of the capacitive element can be improved. Therefore, a display device having a capacitive element with a high transmittance in the pixel portion and capable of increasing the charge capacity can be provided.

[0017] ​Another aspect of the present invention is a transistor having a first oxide semiconductor film in a channel formation region, a first oxide film formed on the first oxide semiconductor film, a second oxide semiconductor film formed on the same surface as the first oxide semiconductor film, a pixel electrode electrically connected to the transistor, and a capacitive element having a dielectric film sandwiched between a pair of electrodes and having translucency. One of the pair of electrodes of the capacitive element having translucency is the second oxide semiconductor film, and the other of the pair of electrodes is the pixel electrode. A display device characterized in that One of the pair of electrodes of the capacitive element having translucency is the second oxide semiconductor film, and is formed in a single layer structure as compared with a stacked film of the first oxide semiconductor film used in the channel formation region of the transistor and the first oxide film formed on the first oxide semiconductor film. Therefore, a display device having a capacitive element with a high transmittance of the pixel portion and capable of increasing the charge capacitance can be provided. Further, since the first oxide film is formed on the first oxide semiconductor film of the transistor, a highly reliable display device can be obtained.

[0018] One of the pair of electrodes of the capacitive element having translucency is the second oxide semiconductor film, and is formed in a single layer structure as compared with a stacked film of the first oxide semiconductor film used in the channel formation region of the transistor and the first oxide film formed on the first oxide semiconductor film. Therefore, a display device having a capacitive element with a high transmittance of the pixel portion and capable of increasing the charge capacitance can be provided. Further, since the first oxide film is formed on the first oxide semiconductor film of the transistor, a highly reliable display device can be obtained. Since the first oxide film is formed on the first oxide semiconductor film of the transistor, a highly reliable display device can be obtained.

Advantages of the Invention

[0019] According to one aspect of the present invention, a display device having a capacitive element with a high aperture ratio and capable of increasing the charge capacitance can be provided. Further, a display device having a capacitive element with a high transmittance of the pixel portion and capable of increasing the charge capacitance can be provided. Further, a display device with low power consumption can be provided.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

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Figure 12

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that its form and details can be variously changed. Also, the present invention is not construed to be limited to the description content of the embodiments shown below.

[0022] In the configuration of the present invention described below, the same parts or parts having the same function are commonly used with the same reference numerals among different drawings, and the repeated description thereof is omitted. Also, when referring to parts having the same function, the hatch patterns are the same, and there are cases where they are not particularly labeled.

[0023] ​​In each of the figures described in this specification, the size, film thickness, or area of each component may be exaggerated for clarity. Therefore, it is not necessarily limited to that scale.

[0024] In this specification and the like, ordinal numbers such as first, second, etc. are used for convenience and do not indicate the process order or stacking order. Therefore, for example, "first" can be appropriately replaced with "second" or "third" etc. for explanation. Also, the ordinal numbers described in this specification etc. may not match the ordinal numbers used to specify an aspect of the present invention.

[0025] Also, the functions of "source" and "drain" in an aspect of the present invention may be interchanged when the direction of current changes during circuit operation. For this reason, in this specification, the terms "source" and "drain" can be used interchangeably.

[0026] (Embodiment 1) In this embodiment, a display device which is an aspect of the present invention will be described with reference to the drawings. Note that in this embodiment, a display device which is an aspect of the present invention will be described by taking a liquid crystal display device as an example.

[0027] <Configuration of the display device> Fig. 1(A) shows an example of a display device. The display device shown in Fig. 1(A) includes a pixel portion 100 , a scanning line driving circuit 104, a signal line driving circuit 106, m scanning lines 107 each arranged parallel or substantially parallel to each other and whose potential is controlled by the scanning line driving circuit 104, and n signal lines each arranged parallel or substantially parallel to each other and whose potential is controlled by the signal line driving circuit 106. ​​​​It has the gate line 109 and the like. Further, the pixel portion 100 includes a plurality of pixels arranged in a matrix. It has 301. Also, along the scanning line 107, capacitors 115 are provided, each arranged parallel or substantially parallel. The capacitor lines 115 may be arranged parallel or substantially parallel along the signal line 109. Also, the scanning line driving circuit 104 and the signal line driving circuit 106 are sometimes collectively referred to as a driving circuit section. Note that in FIG. 1(A), the configuration where the capacitor line 115 is connected to the scanning line driving circuit 104 is illustrated, but it is not limited thereto. For example, the capacitor line 115 may be configured not to be connected to the scanning line driving circuit 104. Although the configuration where the capacitor line 115 is connected to the scanning line driving circuit 104 is illustrated in FIG. 1(A), it is not limited thereto. For example, the capacitor line 115 may be configured not to be connected to the scanning line driving circuit 104.

[0028] Each scanning line 107 is electrically connected to n pixels 301 arranged in one of the rows among the pixels 301 arranged in m rows and n columns in the pixel portion 100. Also, each signal line 109 is electrically connected to m pixels 30 1 arranged in one of the columns among the pixels 301 arranged in m rows and n columns. m and n are both integers of 1 or more. Also, each capacitor line 115 is electrically connected to n pixels 30 1 arranged in one of the rows among the pixels 301 arranged in m rows and n columns. Note that when the capacitor lines 115 are arranged parallel or substantially parallel along the signal line 109, they are electrically connected to m pixels 301 arranged in one of the columns among the pixels 301 arranged in m rows and n columns. When the capacitor lines 115 are arranged parallel or substantially parallel along the signal line 109, they are electrically connected to m pixels 301 arranged in one of the columns among the pixels 301 arranged in m rows and n columns.

[0029] FIG. 1(B) is an example of a circuit diagram of the pixel 301 included in the display device shown in FIG. 1(A). The pixel 301 shown in FIG. 1(B) includes a transistor 103 electrically connected to the scanning line 107 and the signal line 109, and one electrode is electrically connected to the drain of the transistor 103. The pixel 301 shown in FIG. 1(B) includes a transistor 103 electrically connected to the scanning line 107 and the signal line 109, and one electrode is electrically connected to the drain of the transistor 103. A capacitor element 105 electrically connected to a capacitor line 115 that supplies a constant potential from the other electrode , a pixel electrode is electrically connected to the drain of the transistor 103 and one electrode of the capacitor element 105 , and a liquid crystal element 108 electrically connected to a wiring that supplies a counter potential by an electrode (counter electrode) provided facing the pixel electrode .

[0030] The liquid crystal element 108 controls the transmission or non - transmission of light by the optical modulation action of the liquid crystal sandwiched between the substrate on which the transistor 103 and the pixel electrode are formed and the substrate on which the counter electrode is formed . Alternatively, the liquid crystal element 108 controls the transmission or non - transmission of light by the optical modulation action of the liquid crystal sandwiched between the substrate on which the transistor 103, the pixel electrode, and the counter electrode are formed and the sealing substrate . Note that the optical modulation action of the liquid crystal is controlled by an electric field (including a vertical electric field or an oblique electric field) applied to the liquid crystal . When a counter electrode (also referred to as a common electrode) is formed on the substrate on which the pixel electrode is formed, the electric field applied to the liquid crystal is a horizontal electric field . Note that the liquid crystal element 108 can be applied not only to liquid crystal elements but also to various display elements, light - emitting elements, etc . For example, as an example of a display element, a light - emitting element, etc., there are EL (electroluminescence) elements (EL elements including organic and inorganic substances, organic EL elements, inorganic EL elements), LEDs (white LEDs, red LEDs, green LEDs, blue LEDs, etc , transistors (transistors that emit light according to current), electron - emitting elements, liquid crystal elements, electro - ink, electrophoretic elements, grating light valves (GLVs), plasma displays (PDPs)

[0031] ​​​​​​, MEMS (Micro-Electro-Mechanical System), digital micromirror device (DMD), DMS (Digital Microshutter), MIRASOL (registered trademark), IMOD (Interference Modulation) element, piezoelectric ceramic display, carbon nanotube, etc., there are those having a display medium whose contrast, brightness, reflectivity, transmittance, etc. change due to electromagnetic action. As an example of a display device using an EL element, there is an EL display, etc. As an example of a display device using an electron-emitting element, there is a field emission display (FED) or a SED (Surface-conduction Electron-emi tter Display) flat panel display, etc. As an example of a display device using a liquid crystal element, there are a transmissive liquid crystal display device, a transflective liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, a projection liquid crystal display device, etc. As an example of a display device using electronic ink or an electrophoretic element, there is electronic paper, etc.

[0032] Next, a specific example of the pixel 301 of the liquid crystal display device will be described. Here, a top view of a part of the scanning line driving circuit 104 is shown in Fig. 2(A), and a top view of a part of the pixel 301 is shown in Fig. 2( B). In Figs. 2(A) and (B), the counter electrode and the liquid crystal element are omitted from the

[0033] illustration. In Fig. 2(A), a conductive film 304a that functions as a gate, a gate insulating film (not shown in Fig. 2(A)), an oxide semiconductor film 308a in which a channel formation region is formed, and conductive films 310a and 310b that function as a source and a drain constitute the transistor 102. 。The oxide semiconductor film 308a is provided on the gate insulating film. Also, the conductive film 304b formed at the same time as the conductive film 304a, the conductive film 310c formed at the same time as the conductive films 310a and 310b, and the conductive film 316 a having translucency for connecting the conductive film 304b and the conductive film 310c are provided. The conductive film 316a having translucency is connected to the conductive film 30 4b at the opening 374a and is connected to the conductive film 310c at the opening 374b.

[0034] In FIG. 2(B), the conductive film 304c functioning as the scanning line 107 extends in a direction substantially orthogonal to the signal line 109 (the left - right direction in the figure). The conductive film 310d functioning as the signal line 109 extends in a direction substantially orthogonal to the scanning line 107 (the up - down direction in the figure). The conductive film 310f functioning as the capacitance line 115 extends in a direction parallel to the signal line 109. The conductive film 304c functioning as the scanning line 107 is electrically connected to the scanning line driving circuit 104 (see FIG. 1(A)). The conductive film 310d functioning as the signal line 109 and the conductive film 310f functioning as the capacitance line 115 are electrically connected to the signal line driving circuit 106. In FIG. 1(A), the capacitance line 115 is illustrated as being connected to the scanning line driving circuit 104. However, as shown in FIG. 2(B), the capacitance line 115 may be connected to the signal line driving circuit 106. The transistor 103 is provided in a region where the scanning line 107 and the signal line 109 intersect. The transistor 103 includes a conductive film 304c functioning as a gate, a gate insulating film (not shown in FIG. 2 (B)), formed on the gate insulating film and having a channel formation region formed therein.

[0035] ​​​​​​The oxide semiconductor film 308b, and the conductive films 310d and 310e that function as a source and a drain It is configured by. Note that the conductive film 304c also functions as a scanning line, and the region where the oxide semiconductor film 3 overlaps with 08b functions as the gate of the transistor 103. Also, the conductive film 31 0d also functions as a signal line, and the region where it overlaps with the oxide semiconductor film 308b functions as the source or drain of the transistor 103. Also, in FIG. 2(B), the scanning line has an end portion located outside the end portion of the oxide semiconductor film 308b in the upper surface shape. Therefore, the scanning line functions as a light-shielding film that blocks light from a light source such as a backlight. As a result, the oxide semiconductor film 308b included in the transistor is not irradiated with light, and fluctuations in the electrical characteristics of the transistor 10 3 can be suppressed.

[0036] Also, the conductive film 310e is electrically connected to the conductive film 316b having translucency that functions as a pixel electrode in the opening 374c.

[0037] The capacitor element 105 is connected to the conductive film 310f that functions as a capacitor line 115 in the opening 372. Also, the capacitor element 105 includes a conductive film 308c having translucency formed on the gate insulating film, a conductive film 316b having translucency that functions as a pixel electrode, and a dielectric film formed of a nitride insulating film provided on the transistor 103. That is, the capacitor element 105 has translucency. That is, the capacitor element 105 has translucency.

[0038] Since the capacitor element 105 has translucency in this way, the capacitor element 105 can be formed large (with a large area) within the pixel 301. Therefore, it is possible to increase the aperture ratio, It can be 55% or more, preferably 60% or more. Also, the charge capacity A display device with an increased charge capacity can be obtained. For example, in a liquid crystal display device with high resolution the area of the pixel becomes smaller, and the area of the capacitive element also becomes smaller. Therefore, in a display device with high resolution the charge capacity accumulated in the capacitive element becomes smaller. However, since the capacitive element 105 shown in this embodiment has translucency, by providing the capacitive element in the pixel, while obtaining a sufficient charge capacity in each pixel, the aperture ratio can be increased. Typically, it is suitable for a high-resolution display device with a pixel density of 200 ppi or more, and further 300 ppi or more and can be used preferably.

[0039] Also, the film thickness of the translucent conductive film 308c, which is one electrode of the capacitive element 105, is thinner than the oxide semiconductor films 308a and 308b of the thin film transistors 102 and 103. Thus the transmittance of the capacitive element 105 can be improved.

[0040] Also, the pixel 301 shown in FIG. 2(B) has a shape in which the side parallel to the conductive film 310d functioning as a signal line is shorter than the side parallel to the conductive film 304c functioning as a scanning line, and the conductive film 310f functioning as a capacitive line extends in a direction parallel to the conductive film 310d functioning as a signal line. As a result, since the area of the conductive film 310f in the pixel 301 can be reduced, the aperture ratio can be increased. Also, since the conductive film 310f functioning as a capacitive line does not use a connection electrode and directly contacts the translucent conductive film 308c the aperture ratio can be further increased.

[0041] Also, one aspect of the present invention can increase the aperture ratio even in a high-resolution display device and, because the transmittance of the pixels is high, it is possible to efficiently utilize the light of a light source such as a backlight and reduce the power consumption of the display device.

[0042] Next, the sectional views between the dashed-dotted lines A - B and the dashed-dotted lines C - D shown in FIGS. 2(A) and (B) are shown in FIG. 3(A). The display device shown in the present embodiment shown in FIG. 3(A) has a liquid crystal element 108 sandwiched between a pair of substrates (substrate 302 and substrate 34

[0043] 2). The liquid crystal element 108 has a light-transmissive conductive film 316b above the substrate 302, films for controlling alignment (hereinafter referred to as alignment films 318 and 352), a liquid crystal layer 320, and a conductive film 350.

[0044] The light-transmissive conductive film 316b functions as one electrode of the liquid crystal element 108, and the conductive film 350 functions as the other electrode of the liquid crystal element 108.

[0045] As driving methods for a display device having a liquid crystal element, there are TN mode, STN mode, VA mode, ASM (Axially Symmetric Aligned Micro-ce ll) mode, OCB (Optically Compensated Birefri ngence) mode, FLC (Ferroelectric Liquid Crys tal) mode, AFLC (AntiFerroelectric Liquid Cr ystal) mode, MVA (Multi-domain Vertical Alig nment) mode, PVA (Patterned Vertical Alignme nt) mode, IPS mode, FFS mode, or TBA (Transverse Be nd Alignment) mode or the like may be used. Further, as a driving method of a display device having a liquid crystal element, in addition to the driving methods described above, ECB (Electrically C ontrolled Birefringence) mode, PDLC (Polymer Dispersed Liquid Crystal) mode, PNLC (Polym er Network Liquid Crystal) mode, guest-host mode, etc. are available. However, it is not limited thereto, and various driving methods can be used as the driving method of a display device having a liquid crystal element.

[0046] Further, a liquid crystal element may be constituted by a liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent. The liquid crystal exhibiting a blue phase has a response speed of 1 msec or less, which is short, and is optically isotropic, so that alignment treatment is unnecessary and viewing angle dependence is small.

[0047] In this embodiment, a vertical electric field type liquid crystal display device will be described.

[0048] As described above, a liquid crystal display device refers to a device having a liquid crystal element. Note that a liquid crystal display device includes a driving circuit or the like for driving a plurality of pixels. Further, a liquid crystal display device includes a control circuit, a power supply circuit, a signal generation circuit, a backlight module, etc. arranged on another substrate, and may also be called a liquid crystal module.

[0049] In the driving circuit portion, a conductive film 304a that functions as a gate, insulating films 305 and 306 that function as a gate insulating film, an oxide semiconductor film 308a in which a channel formation region is formed, a so ​​​​The transistor 102 is constituted by conductive films 310a and 310b that function as source and drain. The oxide semiconductor film 308a is provided on the gate insulating film. Also, insulating films 312 and 314 are provided as protective films on the oxide semiconductor film 308a and the conductive films 310a and 310b.

[0050] In the pixel portion, the transistor 103 is constituted by a conductive film 304c that functions as a gate, insulating films 305 and 306 that function as gate insulating films, an oxide semiconductor film 308b formed on the gate insulating film in a channel formation region, and conductive films 310d and 310e that function as source and drain. The oxide semiconductor film 308b is provided on the gate insulating film. Also, insulating films 312 and 314 are provided as protective films on the oxide semiconductor film 308b and the conductive films 310d and 310e.

[0051] Also, in the pixel portion, a light-transmissive conductive film 316b that functions as a pixel electrode is connected to the conductive film 310e at an opening provided in the insulating films 312 and 314.

[0052] Also, the capacitor element 105 is constituted by a light-transmissive conductive film 308c that functions as one electrode of the capacitor element 105, an insulating film 314 that functions as a dielectric film of the capacitor element 105, and a light-transmissive conductive film 316b that functions as the other electrode of the capacitor element 105. The light-transmissive conductive film 308c is provided on the gate insulating film. In this way, the light-transmissive conductive film 316b has the function of a pixel electrode and the function of the other electrode of the capacitor element 105.

[0053] In the driving circuit section, the conductive film 304a and the conductive film 304c are formed at the same time. 4b and the conductive film 31 The light-transmitting conductive film 310c is formed at the same time as the light-transmitting conductive film 316b. Connected via 6a.

[0054] In the display device described in this embodiment, a semiconductor film for a capacitor is formed simultaneously with an oxide semiconductor film for a transistor. A light-transmitting conductive film that functions as a pixel electrode is formed. The other electrode of the element is used. Since a process for forming a film is not required, the manufacturing process of a display device can be reduced. Since the pair of electrodes are formed using a conductive film having a light-transmitting property, the electrode has a light-transmitting property. The area occupied by the capacitive element can be increased while increasing the aperture ratio of the pixel.

[0055] The light-transmitting conductive film 308c is formed simultaneously with the oxide semiconductor films 308a and 308b. The oxide semiconductor films 308a and 308b (oxide semiconductor films The first portion is formed by forming the insulating film 306 and the insulating film 312, etc., so as to improve interface characteristics with the oxide semiconductor film. Since the oxide semiconductor film 308a is in contact with the film formed of a material capable of being heated, The oxide semiconductor film 308a and the oxide semiconductor film 308b function as a semiconductor. The sintered material has excellent electrical properties.

[0056] On the other hand, the light-transmitting conductive film 308c (the second portion of the oxide semiconductor film) is formed through the opening 372. The insulating film 314 is in contact with the insulating film 314. The insulating film 314 is resistant to impurities from the outside, such as water, aluminum, etc. It is formed of a material that prevents alkali metals, alkaline earth metals, etc. from diffusing into the oxide semiconductor film and further contains hydrogen. Therefore, when the hydrogen contained in the insulating film 314 diffuses into the transparent conductive film 308c having translucency formed simultaneously with the oxide semiconductor films 308a and 308b, in the transparent conductive film 308c having translucency, hydrogen combines with oxygen to generate carriers, electrons. As a result, the transparent conductive film 308c having translucency has high conductivity and functions as a conductor. That is, the transparent conductive film 308c having translucency can also be said to be an oxide semiconductor film having high conductivity. film, and further contains hydrogen. Therefore, when the hydrogen contained in the insulating film 314 diffuses into the transparent conductive film 308c having translucency formed simultaneously with the oxide semiconductor films 308a and 308b, in the transparent conductive film 308c having translucency, hydrogen combines with oxygen to generate carriers, electrons. As a result, the transparent conductive film 308c having translucency has high conductivity and functions as a conductor. That is, the transparent conductive film 308c having translucency can also be said to be an oxide semiconductor film having high conductivity.

[0057] Also, the transparent conductive film 308c having translucency is thinner in film thickness than the oxide semiconductor films 308a and 308b of the transistors 102 and 103. Therefore, the transmittance of the capacitive element 105 can be improved. The transparent conductive film 308c having translucency can be made thinner in film thickness than the oxide semiconductor films 308a and 308b by processing simultaneously when forming the opening 372. This is possible.

[0058] Here, an enlarged view of the cross-sectional view of the display device shown in Fig. 3(A) is shown in Fig. 3(B). Fig. 3(B) is an enlarged cross-sectional view of a part of the transistor 103 and the capacitive element 105 shown in Fig. 3(A). This is the end.

[0059] As shown in Fig. 3(B), the film thickness of the transparent conductive film 308c having translucency of the capacitive element 105 is thinner than the film thickness of the oxide semiconductor film 308b of the transistor 103. The film thickness of the transparent conductive film 308c having translucency is preferably a film thickness that has conductivity enabling it to function as an electrode of the capacitive element 105 and that can improve the transmittance of the capacitive element. The transparent conductive film 308c having translucency is preferably a film thickness that has conductivity enabling it to function as an electrode of the capacitive element 105 and that can improve the transmittance of the capacitive element. The transparent conductive The film thickness of the electrofilm 308c is, for example, 2 / 3 or less of the film thickness of the oxide semiconductor film 308b, and more preferably 1 / 2 or less.

[0060] Next, the characteristics of the transistor using the oxide semiconductor will be described. The transistor using the oxide semiconductor is an n-channel type transistor. Also, oxygen deficiency contained in the oxide semiconductor may generate carriers, which may deteriorate the electrical characteristics and reliability of the transistor. For example, in the case of an n-channel type transistor, the threshold voltage of the transistor fluctuates in the negative direction, and a drain current may flow when the gate voltage is 0V. In this way, the phenomenon that a drain current flows when the gate voltage is 0V is called non-maryon characteristics, and a transistor having such characteristics is called a depletion type transistor. Note that a transistor that can be regarded as having no drain current flowing when the gate voltage is 0V is called normal-off characteristics, and a transistor having such characteristics is called an enhancement type transistor.

[0061] In the oxide semiconductor films 308a and 308b in which the channel formation regions of the transistors 102 and 103 are formed, it is preferable that defects, typically oxygen deficiency, are reduced as much as possible. By reducing defects, typically oxygen deficiency, contained in the oxide semiconductor film as much as possible, it is possible to suppress the transistors 102 and 103 from having normal-on characteristics, and it is possible to improve the electrical characteristics and reliability of the display device. Also, the power consumption of the display device can be reduced.

[0062] The fluctuation of the threshold voltage of the transistor in the negative direction is not only due to It can also be caused by hydrogen contained in a semiconductor (including hydrogen compounds such as water). Hydrogen contained in an oxide semiconductor reacts with oxygen bonded to a metal atom to form water, and defects (also referred to as oxygen deficiencies) are formed in the lattice from which oxygen has desorbed (or the portion from which oxygen has desorbed). In addition, by a part of hydrogen reacting with oxygen, electrons as carriers are generated, resulting in a tendency for a transistor using an oxide semiconductor containing hydrogen to have normally-on characteristics.

[0063] Therefore, it is preferable that hydrogen is reduced as much as possible in the oxide semiconductor films 308a and 308b in which the channel formation regions of the transistors 102 and 103 are formed. Specifically, in the oxide semiconductor films 308a and 308b, the hydrogen concentration obtained by secondary ion mass spectrometry is less than 5×10 atoms / cm ², preferably less than 5×10 19 atoms / cm 3 ³, preferably less than 1×10 18 atom s / cm 3 ³, more preferably less than 5× 18 atoms / cm 3 ³, still more preferably less than 1×10 10 17 atoms / cm 3 ³, and even more preferably less than 1×10 16 atoms / cm 3 ³ or less.

[0064] In addition, in the oxide semiconductor films 308a and 308b in which the channel formation regions of the transistors 102 and 103 are formed, the concentration of an alkali metal or alkaline earth metalloid obtained by secondary ion mass spectrometry is 1×10 atoms / cm 18 ² or less, preferably 2×10 3 ato 16 ms / cm ² or less.3 Make it as follows. Alkali metals and alkaline earth metals may generate carriers when combined with an oxide semiconductor, which may increase the off-current of transistors 102 and 103.

[0065] Thus, by reducing impurities (such as hydrogen, nitrogen, alkali metals, or alkaline earth metals) in the oxide semiconductor films 308a and 308b as much as possible and making the oxide semiconductor films highly pure, transistors 102 and 103 can be made enhancement-mode, and the normal-on characteristics of transistors 102 and 103 can be suppressed. The off-current of transistors 102 and 103 can be extremely reduced. Therefore, a display device having good electrical characteristics can be fabricated. Also, a display device with improved reliability can be fabricated.

[0066] Note that the low off-current of transistors using highly purified oxide semiconductor films can be proven by various experiments. For example, even in an element with a channel width W of 1×10 μm and a channel length 6 L of 10 μm, in the range of the voltage between the source and the drain (drain voltage) from 1 V to 10 V, the off-current can be below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 A or less. In this case, it can be seen that the value obtained by dividing the off-current by the channel width of the transistor is 100 zA / μm or less. Also, a circuit is used in which a capacitor element and a transistor are connected, and the charge flowing into or out of the capacitor element is controlled by the corresponding transistor to measure the off-current. In this measurement, a highly purified oxide semiconductor film is used in the channel formation region of the above transistor, and the unit of the capacitor element -13 ​​​​​​​​​​​The off-state current of the transistor is measured based on the change in the charge amount per unit time. When the voltage between the source and drain of the transistor is 3 V, the current is reduced to several tens of yA / μm. Therefore, a transistor using a highly purified oxide semiconductor film can have a low off-state current. , the off-current is remarkably small.

[0067] On the other hand, the oxide semiconductor films 308a and 308b of the transistors 102 and 103 The light-transmitting conductive film 308c formed in one step is formed by removing the oxide semiconductor films 308a and 308b. b, the oxygen deficiency and / or hydrogen concentration is high. The conductivity of 08c can be increased.

[0068] Here, other components of the display device shown in FIG. 3(A) will be described below.

[0069] Conductive films 304a, 304b, and 304c are formed on the substrate 302. 04a is formed in the scanning line driving circuit 104 and serves as the gate of a transistor in the driving circuit section. The conductive film 304c is formed in the pixel portion 100 and functions as a transistor in the pixel portion. The conductive film 304b functions as a gate of the scan line driver circuit 104. The conductive film 316a is connected to the conductive film 310c through a light-transmitting conductive film 316a.

[0070] The substrate 302 may be made of aluminosilicate glass, aluminoborosilicate glass, barium oxide glass, or the like. A glass material such as borosilicate glass is used. For mass production, the substrate 302 is made of 8th generation glass. 2nd generation (2160mm x 2460mm), 9th generation (2400mm x 2800mm, or 450mm x 3050mm), 10th generation (2950mm x 3400mm) etc. It is preferable to use a lattice. Since the mother glass shrinks significantly when the processing temperature is high and the processing time is long, when mass-producing using the mother glass, the heat treatment in the manufacturing process is preferably 600 °C or lower, more preferably 450 °C or lower, and even more preferably 350 °C or lower. It is desirable to do so.

[0071] As the conductive films 304a, 304b, and 304c, a metal element selected from aluminum, chromium, copper, tantalum, titanium, molybdenum, tungsten, or an alloy containing the above-described metal element as a component, or an alloy formed by combining the above-described metal elements can be used to form them. Further, the conductive films 304a, 304b, and 304c may have a single-layer structure or a laminated structure of two or more layers. For example, a two-layer structure in which a titanium film is laminated on an aluminum film, a two-layer structure in which a titanium film is laminated on a titanium nitride film, a two-layer structure in which a tungsten film is laminated on a titanium nitride film, a two-layer structure in which a tungsten film is laminated on a tantalum nitride film or a tungsten nitride film, a three-layer structure in which a titanium film, an aluminum film is laminated on the titanium film, and a titanium film is further formed thereon, etc. There are. Further, a film of an element selected from titanium, tantalum, tungsten, molybdenum, chromium, neodymium, scandium, an alloy film formed by combining a plurality of them, or a nitride film may be used for aluminum.

[0072] Insulating films 305 and 306 are formed on the substrate 302 and the conductive films 304a, 304b, and 304c. The insulating films 305 and 306 function as a gate insulating film of the transistor 102 of the scanning line driving circuit 104 and a gate insulating film of the transistor 103 of the pixel portion 100. Have.

[0073] The insulating film 305 is preferably made of a material that prevents impurities from the outside, such as water, alkali metals, alkaline earth metals, etc., from diffusing into the oxide semiconductor film. Furthermore, it preferably contains hydrogen. The insulating film 305 is typically a nitride insulating film. Examples of the nitride insulating film include a silicon nitride film, a silicon oxynitride film, an aluminum nitride film, an aluminum oxynitride film, etc., and can be provided in a laminated or single-layer structure. When the insulating film 305 has a laminated structure, for example, as the first silicon nitride film, a silicon nitride film with few defects is used, and on the first silicon nitride film, as the second silicon nitride film, a silicon nitride film with a low hydrogen emission amount is preferably provided. As a result, the hydrogen and nitrogen contained in the insulating film 305 can be suppressed from moving or diffusing into the oxide semiconductor films 308a and 308b. Note that silicon oxynitride refers to an insulating material in which the oxygen content is greater than the nitrogen content. Also, silicon nitride oxide refers to an insulating material in which the nitrogen content is greater than the oxygen content. The insulating film 306 is preferably made of a material that can improve the interface characteristics with the oxide semiconductor films 308a and 308b. Typically, it is preferable to use an inorganic insulating material containing oxygen. The insulating film 306 is typically an oxide insulating film. Examples of the oxide insulating film include a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, an aluminum oxynitride film, etc., and can be provided in a laminated or single-layer structure. In addition, as the insulating film 306, hafnium silicate (HfSiO

[0074] Note that silicon oxynitride refers to an insulating material in which the oxygen content is greater than the nitrogen content. Also, silicon nitride oxide refers to an insulating material in which the nitrogen content is greater than the oxygen content. Note that silicon oxynitride refers to an insulating material in which the oxygen content is greater than the nitrogen content. Also, silicon nitride oxide refers to an insulating material in which the nitrogen content is greater than the oxygen content. Note that silicon oxynitride refers to an insulating material in which the oxygen content is greater than the nitrogen content. Also, silicon nitride oxide refers to an insulating material in which the nitrogen content is greater than the oxygen content.

[0075] The insulating film 306 is preferably made of a material that can improve the interface characteristics with the oxide semiconductor films 308a and 308b. Typically, it is preferable to use an inorganic insulating material containing oxygen. The insulating film 306 is typically an oxide insulating film. Examples of the oxide insulating film include a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, an aluminum oxynitride film, etc., and can be provided in a laminated or single-layer structure. In addition, as the insulating film 306, hafnium silicate (HfSiO For example, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, an aluminum oxynitride film, etc. can be used and provided in a laminated or single-layer structure. In addition, as the insulating film 306, hafnium silicate (HfSiO

[0076] In addition, as the insulating film 306, hafnium silicate (HfSiO x ) or hafnium silicate with nitrogen (HfSi )x O y N z ) hafnium aluminate having nitrogen (H fAl x O y N z ), by using high-k materials such as hafnium oxide and yttrium oxide, the gate leakage of transistors 102 and 103 can be reduced.

[0077] The silicon nitride film has a higher relative dielectric constant than the silicon oxide film and requires a larger film thickness to obtain the same capacitance as the silicon oxide film. Therefore, the gate insulating film can be physically thickened. Thus, a decrease in the breakdown voltage of the transistor can be suppressed, and furthermore, the breakdown voltage can be improved, and electrostatic breakdown of the transistor can be suppressed.

[0078] Also, on the insulating film 306, oxide semiconductor films 308a, 308b, and a conductive film 308c having translucency are formed. The oxide semiconductor film 308a is formed at a position overlapping the conductive film 304a and functions as a channel formation region of the transistor 102 in the drive circuit section. Also, the oxide semiconductor film 308b is formed at a position overlapping the conductive film 304c and functions as a channel formation region of the transistor 103 in the pixel section 10 0. The conductive film 30 8c having translucency functions as one electrode of the capacitor element 105.

[0079] The oxide semiconductor films 308a and 308b are oxide semiconductor films containing In or Ga, and typically include In-Ga oxide, In-Zn oxide, In-M-Zn oxide (M is Al , Ti, Ga, Y, Zr, La, Ce, Nd, or Hf).

[0080] When the oxide semiconductor films 308a and 308b are In-M-Zn oxide, In and The atomic ratio of M is preferably less than 50 atomic % for In and 50 atomic % or more for M, more preferably less than 25 atomic % for In and 75 atomic % or more for M.

[0081] The content of the materials contained in the oxide semiconductor films 308a and 308b (for example, In, Ga, etc. ) can be compared by time-of-flight secondary ion mass spectrometry (TOF-SIMS) or X-ray photoelectron spectroscopy (XPS).

[0082] Since the oxide semiconductor films 308a and 308b have an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more, the off-current of the transistors formed later can be reduced.

[0083] The conductive film 308c having translucency is, like the oxide semiconductor films 308a and 308b, an oxide semiconductor film containing In or Ga and is characterized by containing impurities. Hydrogen is one of the impurities. Instead of hydrogen, boron, phosphorus, sulfur, antimony, noble gas elements, alkali metals, alkaline earth metals, etc. may be contained as impurities.

[0084] Both the oxide semiconductor films 308a and 308b and the conductive film 308c having translucency are formed on the gate insulating film and are oxide semiconductor films containing In or Ga, but have different impurity concentrations. Specifically, the impurity concentration of the conductive film 308c having translucency is higher than that of the oxide semiconductor films 308a and 308b. For example, the hydrogen concentration contained in the oxide semiconductor films 308a and 308b is less than 5×10 atoms / cm 19 , preferably less than 5×10 3 19 atoms / cm 3 19 ​​18 atom s / cm 3 less than, preferably 1×10 18 atoms / cm 3 or less, more preferably 5× 10 17 atoms / cm 3 or less, even more preferably 1×10 16 atoms / cm 3 or less, and the hydrogen concentration contained in the conductive film 308c having translucency is 8×10 atom 19 s / cm s / cm 3 or more, preferably 1×10 20 atoms / cm 3 or more, more preferably 5× 10 20 atoms / cm 3 or more. Further, compared with the oxide semiconductor films 308a and 308b, the hydrogen concentration contained in the conductive film 308c having translucency is 2 times, preferably 10 times or more than that of the oxide semiconductor films 308a and 308b.

[0085] Further, the conductive film 308c having translucency has a lower resistivity than the oxide semiconductor films 308a and 308b. The resistivity of the conductive film 308c having translucency is preferably 1×10 times or more and 1×10 times or less of the resistivity of the oxide semiconductor films 308a and 308 -8 times, and typically -1 1×10 1×10 -3 Ωcm or more and 1×10 4 Ωcm less, and even more preferably, the resistivity is 1×10 - 3 Ωcm or more and 1×10 -1 Ωcm less.

[0086] The oxide semiconductor films 308a, 308b, and the conductive film 308c having translucency may have, for example, a non single crystal structure. The non-single crystal structure is, for example, CAAC-OS (C Axis ​Aligned Crystalline Oxide Semiconductor ) includes a polycrystalline structure, a microcrystalline structure described later, or an amorphous structure.

[0087] Note that the oxide semiconductor films 308a, 308b, and the conductive film 308c having translucency are C AAC-OS, a mixed film having regions of two or more structures of a microcrystalline structure and an amorphous structure may be. The mixed film has, for example, a region of an amorphous structure, a region of a microcrystalline structure, and a region of CAAC-O S. Further, the mixed film may have, for example, a laminated structure of a region of an amorphous structure, a region of a microcrystalline structure, and a region of CAAC-OS.

[0088] Note that the oxide semiconductor film may have, for example, a single crystal.

[0089] On the insulating film 306, the oxide semiconductor films 308a, 308b, and the conductive film 308 c, a conductive film (hereinafter referred to as conductive films 310a, 310b, 310c, 310d, 310e ) is formed. Further, the conductive film 310a is electrically connected to the oxide semiconductor film 308a and functions as one of the source and drain of the transistor 102 in the drive circuit section. Further, the conductive film 310b is electrically connected to the oxide semiconductor film 308a and functions as the other of the source and drain of the transistor 102 in the drive circuit section. Further, the conductive film 310c is electrically connected to the conductive film 316a having translucency through openings provided in the insulating film 312 and the insulating film 314. Further, the conductive film 310d is electrically connected to the oxide semiconductor film 308b and functions as one of the source and drain of the transistor 103 in the pixel section. Is electrically connected to the conductive film 316b having translucency, and functions as the other of the source and drain of the transistor in the pixel portion It has the function as the other of the source and drain that the 103 has.

[0090] As the conductive films 310a, 310b, 310c, 310d, 310e, as the conductive material , aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molyb Den, silver, tantalum, or tungsten single metal, or an alloy having this as a main component Is used as a single-layer structure or a laminated structure. For example, a two-layer structure in which a titanium film is laminated on an aluminum film, a two-layer structure in which a titanium film is laminated on a tungsten film, copper-magnesium- A two-layer structure in which a copper film is laminated on an aluminum alloy film, a titanium film or a titanium nitride film, and an aluminum film or a copper film is laminated on the titanium film or the titanium nitride film, and further A three-layer structure in which a titanium film or a titanium nitride film is formed thereon, a molybdenum film or a molybdenum nitride film, and an aluminum film or a copper film is laminated on the molybdenum film or the molybdenum nitride film, and further A three-layer structure in which a molybdenum film or a molybdenum nitride film is formed thereon, etc. are available. In addition, a transparent conductive material containing indium oxide, tin oxide or zinc oxide may be used . And, an aluminum film or a copper film is laminated on the molybdenum film or the molybdenum nitride film, and further a molybdenum film or a molybdenum nitride film is formed thereon . There is. Note that a transparent conductive material containing indium oxide, tin oxide or zinc oxide may be used .

[0091] On the insulating film 306, the oxide semiconductor films 308a, 308b, the conductive film 308c having translucency, And on the conductive films 310a, 310b, 310c, 310d, 310e, an insulating film 312, An insulating film 314 is formed. The insulating film 312 is preferably made of a material capable of improving the interface characteristics with the oxide semiconductor film, similarly to the insulating film 306. The insulating film 314 Is, similarly to the insulating film 305, impurities from the outside, for example, water, alkali metal, alkaline earth Metal, etc. It is preferable to use a material that prevents diffusion of metal or the like into the oxide semiconductor films 308a and 308b. Preferably.

[0092] Further, the insulating film 312 may be formed of an insulating oxide film containing more oxygen than oxygen with a stoichiometric composition. By doing so, desorption of oxygen from the oxide semiconductor films 308a and 308b can be prevented, and oxygen contained in the insulating film 312 can be transferred to the oxide semiconductor film to fill oxygen vacancies. For example, by temperature-programmed desorption gas analysis (hereinafter referred to as TDS analysis), the amount of oxygen molecules released in a heat treatment at 100°C or higher and 700°C or lower, preferably 100°C or higher and 500°C or lower, is 1.0×10 By using an insulating oxide film having more than the above, oxygen vacancies contained in the oxide semiconductor films 308a and 308b can be filled. above molecules / cm above. above and 500°C or lower, preferably 100°C or higher and 500°C or lower, the amount of oxygen molecules released in the heat treatment is 1.0×10 18 molecules / cm 3 above. By using an insulating oxide film having more than the above, oxygen vacancies contained in the oxide semiconductor films 308a and 308b can be filled. It is possible to fill the oxygen vacancies contained in the oxide semiconductor films 308a and 308b.

[0093] Further, the insulating film 312 may have a laminated structure, and a first insulating oxide film having a low interface level with the oxide semiconductor films 308a and 308b may be provided on the side in contact with the oxide semiconductor films 308a and 308b, and an insulating oxide film containing more oxygen than oxygen with the above stoichiometric composition may be provided thereon as a second insulating oxide film. For example, as the first insulating oxide film, the spin density of g value = 2.001 (E´ -center) by electron spin resonance measurement is 3.0×10 spins / cm

[0094] For example, as the first insulating oxide film, the spin density of g value = 2.001 (E´ -center) by electron spin resonance measurement is 3.0×10 17 spins / cm 3 or less, preferably 5.0×10 16 spins / cm 3 or less. By using an insulating oxide film having the above spin density, the oxide semiconductor film It is possible to reduce the interface level with 308a and 308b. Note that the spin density with a g value of 2.001 by electron spin resonance measurement corresponds to the abundance of dangling bonds contained in the first insulating oxide film.

[0095] In addition, transparent conductive films 316a and 316b are formed on the insulating film 314. The transparent conductive film 316a is electrically connected to the conductive film 304b at the opening 374a and electrically connected to the conductive film 310c at the opening 374b. That is, the transparent conductive film 316a functions as a connection electrode that connects the conductive film 304b and the conductive film 310c. Further, the transparent conductive film 316b is electrically connected to the conductive film 310e at the opening 374c and functions as a pixel electrode of the pixel. In addition, the transparent conductive film 316b can function as the other of the pair of electrodes of the capacitor element 105.

[0096] The transparent conductive films 316a and 316b contain at least one oxide selected from the group consisting of indium oxide, tin oxide, and lead oxide. As the transparent conductive films 316a and 316b, for example, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, ITO, indium zinc oxide, indium tin oxide added with silicon oxide, and other transparent conductive materials can be used.

[0097] Further, a colored film (hereinafter referred to as the colored film 346) is formed below the substrate 342. The colored film 346 functions as a color filter. Also, the colored film 3 ​ A light-shielding film 344 adjacent to 46 is formed below the substrate 342. The light-shielding film 344 functions as a black matrix. Also, the colored film 346 does not necessarily have to be provided. For example, when the display device is black and white, etc., the colored film 346 may not be provided. As the colored film 346, any colored film that transmits light in a specific wavelength band may be used. For example, a red (R) color filter that transmits light in the red wavelength band, a green (G) color filter that transmits light in the green wavelength band, a blue (B) color filter that transmits light in the blue wavelength band, etc. can be used.

[0098] As the light-shielding film 344, it only needs to have a function of blocking light in a specific wavelength band, and a metal film or an organic insulating film containing a black pigment, etc. can be used. a red (R) color filter that transmits light in the red wavelength band, a green (G) color filter that transmits light in the green wavelength band, a blue (B) color filter that transmits light in the blue wavelength band, etc. can be used. a green (G) color filter that transmits light in the green wavelength band, a blue (B) color filter that transmits light in the blue wavelength band, etc. can be used. a green (G) color filter that transmits light in the green wavelength band, a blue (B) color filter that transmits light in the blue wavelength band, etc. can be used.

[0099] As the light-shielding film 344, it only needs to have a function of blocking light in a specific wavelength band, and a metal film or an organic insulating film containing a black pigment, etc. can be used. a metal film or an organic insulating film containing a black pigment, etc. can be used.

[0100] Also, an insulating film 348 is formed below the colored film 346. The insulating film 348 has a function as a planarization layer or a function of suppressing the diffusion of impurities that the colored film 346 may contain to the liquid crystal element side. As the light-shielding film 344, it only needs to have a function of blocking light in a specific wavelength band, and a metal film or an organic insulating film containing a black pigment, etc. can be used. As the light-shielding film 344, it only needs to have a function of blocking light in a specific wavelength band, and a metal film or an organic insulating film containing a black pigment, etc. can be used.

[0101] Also, a conductive film 350 is formed on the insulating film 348. The conductive film 350 functions as one of a pair of electrodes of the liquid crystal element 108 in the pixel portion. Note that alignment films 318 and 352 are formed in contact with the conductive films 316a, 316b having translucency and the conductive film 350. As the light-shielding film 344, it only needs to have a function of blocking light in a specific wavelength band, and a metal film or an organic insulating film containing a black pigment, etc. can be used. As the light-shielding film 344, it only needs to have a function of blocking light in a specific wavelength band, and a metal film or an organic insulating film containing a black pigment, etc. can be used. Also, a liquid crystal layer 320 is formed between the conductive film 316b having translucency and the conductive film 350, more specifically, between the alignment film 318 and the alignment film 352. Also, the liquid crystal layer 320 is

[0102] Also, a liquid crystal layer 320 is formed between the conductive film 316b having translucency and the conductive film 350, more specifically, between the alignment film 318 and the alignment film 352. Also, the liquid crystal layer 320 is formed between the conductive film 316b having translucency and the conductive film 350, more specifically, between the alignment film 318 and the alignment film 352. Also, the liquid crystal layer 320 is It is sealed between the substrate 302 and the substrate 342 using a sealing material (not shown). Note that the sealing material preferably has a configuration that contacts an inorganic material in order to suppress the entry of moisture and the like from the outside.

[0103] Also, a spacer for maintaining the thickness (also referred to as the cell gap) of the liquid crystal layer 320 may be provided between the transparent conductive films 316a, 316b and the conductive film 350.

[0104] <Fabrication method of display device> Next, a method for fabricating the element portion provided on the substrate 302 of the display device shown in FIG. 3(A) will be described with reference to FIGS. 4 to 7.

[0105] First, the substrate 302 is prepared. Here, a glass substrate is used as the substrate 302.

[0106] Next, a conductive film is formed on the substrate 302, and the conductive film is processed into a desired shape to form the conductive films 304a, 304b, and 304c. Note that the formation of the conductive films 304a, 304b, and 304c can be performed by forming a mask by first patterning in a desired region and etching the region not covered by the mask. (See FIG. 4(A)). Also, the conductive films 304a, 304b, and 304c can typically be formed using a vapor deposition method, a CVD method, a sputtering method, a spin coating method, or the like. Here, tungsten films with a thickness of 100 nm are formed as the conductive films 304a, 304b, and 304c by sputtering. c

[0107] 4a, 304b, and 304c

[0108] Next, an insulating film 305 is formed on the substrate 302 and the conductive films 304a, 304b, and 304c. ​​​​​​​Form and form an insulating film 306 on the insulating film 305 (see Fig. 4(A)).

[0109] The insulating film 305 and the insulating film 306 can be formed by a sputtering method, a CVD method, or the like. Note that it is preferable to form the insulating film 305 and the insulating film 306 continuously in a vacuum to suppress the incorporation of impurities at the interface between the insulating film 305 and the insulating film 306. Here, as the insulating film 305, a silicon nitride film with a thickness of 400 nm is formed by the PE-CVD method. Also, as the insulating film 306, a silicon oxynitride film with a thickness of 50 nm is formed by the PE-CVD method.

[0110] Next, form an oxide semiconductor film 307 on the insulating film 306 (see Fig. 4(B)).

[0111] The oxide semiconductor film 307 can be formed using a sputtering method, a coating method, a pulsed laser deposition method, a laser ablation method, or the like.

[0112] When forming the oxide semiconductor film 307 by the sputtering method, a power supply device for generating plasma can be appropriately used, such as an RF power supply device, an AC power supply device, or a DC power supply device.

[0113] As the sputtering gas, a noble gas (typically argon), oxygen, or a mixed gas of a noble gas and oxygen can be appropriately used. In the case of a mixed gas of a noble gas and oxygen, it is preferable to increase the gas ratio of oxygen with respect to the noble gas.

[0114] Note that when forming the oxide semiconductor film 307, for example, when using the sputtering method, the substrate temperature is 20°C (room temperature) or higher and lower than 500°C, preferably the substrate temperature is 100°C or higher ​​​​​​​​Oxidation may be carried out while heating at 450 °C or lower, more preferably 150 °C or higher and 350 °C or lower. An oxide semiconductor film 307 may be formed.

[0115] When forming the oxide semiconductor film 307 by sputtering, in order to reduce the hydrogen concentration in the oxide semiconductor film 307, each chamber in the sputtering apparatus is evacuated to a high vacuum (5 × 10 Pa to 1 × 10 Pa or so) using an adsorption type vacuum exhaust pump such as a cryopump that can remove hydrogen and the like that are impurities for the oxide semiconductor film as much as possible. Alternatively, it is preferable to combine a turbo molecular pump and a cold trap so that gas, particularly gas containing carbon or hydrogen, does not flow back into the chamber from the exhaust system. -7 - 4

[0116] In addition, in order to reduce the hydrogen concentration in the oxide semiconductor film 307, not only is the chamber evacuated to a high vacuum, but also the sputtering gas needs to be highly purified. The oxygen gas or argon gas used as the sputtering gas should be a gas purified to a dew point of -40 °C or lower, preferably -80 °C or lower, more preferably -100 °C or lower, and even more preferably -120 °C or lower, so as to prevent moisture and the like from being incorporated into the oxide semiconductor film as much as possible.

[0117] Here, an In-Ga-Zn oxide film (In:Ga:Zn = 1:1:1) with a thickness of 35 to 100 nm is formed as the oxide semiconductor film 307 by sputtering.

[0118] Next, by processing the oxide semiconductor film 307 into a desired shape, an island-shaped oxide semiconductor film 3 ​​​​​​​​​​Form 08a, 308b, and 308d (see Fig. 4(C)).

[0119] Note that the formation of the oxide semiconductor films 308a, 308b, and 308d can be achieved by forming a mask by photolithography in a desired region and etching the region not covered by the mask. As the etching, dry etching, wet etching, or a combination of both can be used.

[0120] Next, it is preferable to perform a first heat treatment. The first heat treatment can be carried out at a temperature of 250°C or higher and 650°C or lower, preferably 300°C or higher and 500°C or lower, in an inert gas atmosphere, an atmosphere containing 10 ppm or more of an oxidizing gas, or under reduced pressure. Also, the atmosphere for the first heat treatment may be an atmosphere containing 10 ppm or more of an oxidizing gas to supplement the desorbed oxygen after heat treatment in an inert gas atmosphere. By the first heat treatment, the crystallinity of the oxide semiconductor used for the oxide semiconductor films 308a, 308b, and 308d can be enhanced, and furthermore, impurities such as hydrogen and water can be removed from the insulating film 306 and the oxide semiconductor films 308a, 308b, and 308d. Note that the first heating step may be performed before etching the oxide semiconductor.

[0121] Here, heat treatment is performed for 1 hour in a nitrogen atmosphere at 350°C, and then heat treatment is performed for 1 hour in an oxygen atmosphere at 350°C.

[0122] Next, a conductive film 309 is formed on the insulating film 306 and the oxide semiconductor films 308a, 308b, and 308d (see Fig. 5(A)).

[0123] ​​​​​​​​​​​​​As the conductive film 309, for example, it can be formed using a sputtering method.

[0124] Here, a titanium film with a thickness of 50 nm, an aluminum film with a thickness of 400 nm, and a titanium film with a thickness of 10 0 nm are sequentially laminated by the sputtering method.

[0125] Next, by processing the conductive film 309 into a desired region, conductive films 310a, 310b, 31 0c, 310d, 310e are formed. Note that the formation of the conductive films 310a, 310b, 310c, 3 10d, 310e can be formed by forming a mask by a third patterning in a desired region , and etching the region not covered by the mask (see Fig. 5( B)).

[0126] Next, an insulating film 311 is formed so as to cover the insulating film 306, the oxide semiconductor films 308a, 308b, 308d, and the conductive films 31 0a, 310b, 310c, 310d, 310e (see Fig. 5(C)).

[0127] As the insulating film 311, it is preferable to use a material capable of improving the interface characteristics with the oxide semiconductor films 308a, 308b, 308d. Typically, it is preferable to use an inorganic insulating material containing oxygen. For example, an insulating oxide film can be used. Further, as the insulating film 3 11, for example, it can be formed using a PE-CVD method, a sputtering method, or the like.

[0128] When the insulating film 311 is formed of an insulating oxide film containing more oxygen than the oxygen satisfying the stoichiometric composition, the insulating film 311 can be formed using the following formation conditions. Here ​​Here, the case of forming a silicon oxide film or a silicon oxynitride film as the insulating film 311 will be described. The formation conditions are as follows: The substrate placed in the evacuated processing chamber of the PE-CVD apparatus is held at 180°C or higher and 260°C or lower, more preferably 180°C or higher and 230°C or lower. A source gas is introduced into the processing chamber to set the pressure in the processing chamber at 100 Pa or higher and 250 Pa or lower, more preferably 100 Pa or higher and 200 Pa or lower. High-frequency power of 0.17 W / cm² or higher and 0.5 W / cm² or lower, more preferably 0.25 W / cm² or higher and 0.35 W / cm² or lower, is supplied to the electrode provided in the processing chamber. The source gas for the insulating film 311 includes, as typical examples of the depositable gas containing silicon, silane, disilane, trisilane, silane fluoride, etc. As the oxidizing gas, there are oxygen, ozone, nitrous oxide, nitrogen dioxide, etc. By supplying the high-frequency power of the above power density in the processing chamber at the above pressure, the decomposition efficiency of the source gas in the plasma increases, the oxygen radicals increase, and the oxidation of the source gas proceeds. Therefore, the oxygen content in the insulating film 311 becomes more than the stoichiometric composition. However, when the substrate temperature is at the above temperature, since the bonding force between silicon and oxygen is weak, part of the oxygen desorbs due to heating. As a result, an oxide insulating film containing more oxygen than the oxygen satisfying the stoichiometric composition and from which part of the oxygen desorbs due to heating can be formed. Also, the insulating film 311 has a laminated structure. As the first oxide insulating film, at least an oxide semiconductor 2 2 2 2

[0129]

[0130]

[0131] ​​​​​​​​​​​​​​​​​​ An insulating oxide film with a lower interface level with the body films 308a and 308b is provided, and an insulating oxide film containing more oxygen than oxygen satisfying the stoichiometric composition is provided thereon as the second insulating oxide film. It may be provided.

[0132] At least the insulating oxide film with a lower interface level with the oxide semiconductor films 308a and 308b can be formed using the following formation conditions. Here, the case of forming a silicon oxide film or a silicon oxynitride film as the insulating oxide film will be described. The formation conditions are as follows: The substrate placed in the evacuated processing chamber of a PE-CVD apparatus is held at 180°C or higher and 400°C or lower, more preferably 200°C or higher and 370°C or lower. A deposition gas containing silicon as a raw material gas and an oxidizing gas are introduced into the processing chamber to make the pressure in the processing chamber 20 Pa or higher and 250 Pa or lower, more preferably 40 Pa or higher and 200 Pa or lower, and high-frequency power is supplied to the electrode provided in the processing chamber.

[0133] The raw material gas of the first insulating oxide film can be a raw material gas applicable to an insulating oxide film containing more oxygen than oxygen satisfying the stoichiometric composition. The first insulating oxide film serves as a protective film for at least the oxide semiconductor films 308a and 308b in the formation process of the second insulating oxide film. As a result, even when the second insulating oxide film is formed using high-frequency power with a high power density, damage to the oxide semiconductor films 308a and 308b can be suppressed.

[0134] Here, the insulating film 311 has a laminated structure of the first insulating oxide film and the second insulating oxide film. As the first insulating oxide film, silane with a flow rate of 30 sccm and nitrous oxide with a flow rate of 4000 sccm ​​​​​​​​​​​​​Using nitrogen as the source gas, the pressure in the processing chamber is set to 200 Pa, the substrate temperature is set to 220 °C, and 150 W of high-frequency power is supplied to the parallel plate electrode using a 27.12 MHz high-frequency power supply. A silicon oxynitride film with a thickness of 50 nm is formed by a PE-CV D apparatus. As the second insulating oxide film, silane with a flow rate of 200 sccm and dinitrogen monoxide with a flow rate of 4000 sccm are used as the source gases , the pressure in the processing chamber is set to 200 Pa, the substrate temperature is set to 220 °C, and a 27.12 MHz high-frequency power supply is used to supply 1500 W of high-frequency power to the parallel plate electrode. A silicon oxynitride film with a thickness of 400 nm is formed by a PE-CVD apparatus. The PE-CVD apparatus is a parallel plate type PE-CVD apparatus with an electrode area of 6 000 cm 2 . When the supplied power is converted to power per unit area (power density), it is 0.26 W / cm . 2 .

[0135] Next, by processing the insulating film 311 into a desired shape, an insulating film 312 and an opening 372 are formed. The formation of the opening 372 can be achieved by forming a mask by a fourth patterning in a desired region and etching the region not covered by the mask . (See FIG. 6(A)). .

[0136] Note that the opening 372 is formed so that the oxide semiconductor film 308d is exposed. Also, due to the formation of the opening 372, the oxide semiconductor film 308d (the second part of the oxide semiconductor film 307 ) becomes thinner than the oxide semiconductor films 308a and 308b (the first part of the oxide semiconductor film 307). Specifically, the thickness of the oxide semiconductor film 308d is 2 / 3 or less, more preferably 1 / 2 or less, of the thickness of the oxide semiconductor films 308a and 308b. Note that the oxide semiconductor ​ The lower limit of the film thickness of the film 308d is such that the transparent conductive film 308c formed later can function as one of the electrodes of the capacitive element as long as it is within a range where it can function, and for example, it can be set to 5 nm or more and 50 nm or less can be. By setting the film thickness of the oxide semiconductor film 308d within the above range, the transmittance of the oxide semiconductor film 308d can be improved compared to the oxide semiconductor films 308a and 308b . In this embodiment, since the oxide semiconductor film 307 is formed with a thickness of 35 to 100 nm , the film thickness of the oxide semiconductor film 308d can be, for example, 15 nm or more and 50 nm or less .

[0137] As a method for forming the opening 372, for example, a dry etching method can be used . However, the method for forming the opening 372 is not limited to this, and a wet etching method , or a forming method combining the dry etching method and the wet etching method may also be used .

[0138] Also, in this embodiment, the opening 372 is formed so that the outer periphery of the oxide semiconductor film 308d is covered by the insulating film 312, but it is not limited to this. For example, when forming the opening 37 2, the entire surface of the oxide semiconductor film 308d may be exposed, and the film thickness of the entire surface of the oxide semiconductor film 308 d may be thinned.

[0139] Next, an insulating film 313 is formed on the insulating film 312 and the oxide semiconductor film 308d. By forming the insulating film 313, the oxide semiconductor film 308d becomes a transparent conductive film 3 08c (see Fig. 6(B)).

[0140] The insulating film 313 prevents impurities from the outside, such as water, alkali metals, alkaline earth metals, etc. is a film formed of a material that prevents diffusion into the oxide semiconductor film, and further contains hydrogen. Therefore, when hydrogen in the insulating film 313 diffuses into the oxide semiconductor film 308d, the oxide semiconductor in the film 308d, hydrogen combines with oxygen to generate electrons as carriers. As a result, the oxide semiconductor film 308d becomes a conductive film 308c with high conductivity and light transmittance. On the other hand, the oxide semiconductor films 308a and 308b have an insulating film 312 between them and the insulating film 313, so there is no or extremely little diffusion of hydrogen contained in the insulating film 313. For the insulating film 313, for example, a silicon nitride film can be used. The insulating film 313 can be formed, for example, by PE-C VD method.

[0141] The silicon nitride film is preferably formed at a high temperature in order to enhance the blocking property. For example, the substrate temperature is 100 °C or higher and below the strain point of the substrate, more preferably 300 °C or higher and 400 °C or lower. When forming the film at a high temperature, oxygen may desorb from the oxide semiconductor used as the oxide semiconductor films 308a and 308b, resulting in an increase in the carrier concentration. Therefore, the temperature is set such that such a phenomenon does not occur.

[0142] Here, as the insulating film 313, silane with a flow rate of 50 sccm, nitrogen with a flow rate of 5000 sccm, and ammonia with a flow rate of 100 sccm are used as source gases, the pressure in the processing chamber is 200 P a, the substrate temperature is 220 °C, and a high-frequency power of 1000 W (as the power density is 1.6×10 -1 W / cm 2 ) is supplied to the parallel plate electrode using a 27.12 MHz high-frequency power source, and a silicon nitride film with a thickness of 50 nm is formed by PE -CVD method.

[0143] Next, by processing the insulating film 313 into a desired shape, an insulating film 314 and openings 374 a, 374b, and 374c are formed. Note that the insulating film 314 and the openings 374a, 374 b, 374c can be formed by forming a mask by fifth patterning in a desired region and etching the region not covered by the mask (see Fig. 6(C)).

[0144] Also, the opening 374a is formed so that the conductive film 304a is exposed. Also, the opening 3 74b is formed so that the conductive film 310c is exposed. Also, the opening 374c is formed so that the conductive film 310e is exposed.

[0145] Note that as a method for forming the openings 374a, 374b, 374c, for example, a dry etching method can be used. However, the method for forming the openings 374a, 374b, 374c is not limited to this, and a wet etching method, or a forming method combining a dry etching method and a wet etching method may also be used.

[0146] Next, a conductive film 31 5 is formed on the insulating film 314 so as to cover the openings 374a, 374b, 374c (see Fig. 7(A)).

[0147] As the conductive film 315, for example, it can be formed using a sputtering method.

[0148] Here, as the conductive film 315, an indium tin oxide film added with 100 nm thick silicon oxide is formed by a sputtering method.

[0149] Next, by processing the conductive film 315 into a desired shape, a conductive film 316a having translucency, Form 316b. Note that the formation of the conductive films 316a and 316b having translucency is performed by forming a mask by sixth patterning in a desired region, and etching the region not covered by the mask (see FIG. 7(B)).

[0150] In the above steps, a pixel portion and a drive circuit portion having transistors can be formed on the substrate 302. Note that in the manufacturing process shown in this embodiment, the first to sixth patterning, that is, the transistors 102, 103, and the capacitor element 105 can be formed simultaneously with six masks.

[0151] Note that in this embodiment, the hydrogen contained in the insulating film 314 is diffused into the oxide semiconductor film 308d to enhance the conductivity of the oxide semiconductor film 308d. However, the oxide semiconductor films 308a and 308b are covered with a mask, and impurities, typically hydrogen, boron, phosphorus, tin, antimony, noble gas elements, alkali metals, alkaline earth metals, etc. may be added to the oxide semiconductor film 308d to enhance the conductivity of the oxide semiconductor film 308d. As a method of adding hydrogen, boron, phosphorus, tin, antimony, noble gas elements, etc. to the oxide semiconductor film 308d, there are ion doping method, ion implantation method, plasma treatment, etc. On the other hand, as a method of adding alkali metals, alkaline earth metals, etc. to the oxide semiconductor film 308d, there is a method of exposing the oxide semiconductor film 308d to a solution containing the impurities. For example, there are ion doping method, ion implantation method, plasma treatment, etc. As a method of adding alkali metals, alkaline earth metals, etc. to the oxide semiconductor film 308d, there is a method of exposing the oxide semiconductor film 308d to a solution containing the impurities.

[0152] Next, the structure formed on the substrate 342 provided opposite to the substrate 302 will be described below.

[0153] First, prepare a substrate 342. As the substrate 342, the materials shown in the substrate 302 can be adopted. Next, form a light-shielding film 344 and a colored film 346 on the substrate 342. The light-shielding film 344 and the colored film 346 are formed at desired positions respectively by using various materials and methods such as printing method, inkjet method, and etching method using photolithography graphy technology.

[0154] Next, form an insulating film 348 on the light-shielding film 344 and the colored film 346. As the insulating film 348, for example, an organic insulating film such as an acrylic resin can be used. By forming the insulating film 348, for example, impurities contained in the colored film 346 can be suppressed from diffusing to the liquid crystal layer 320 side. However, the insulating film 348 does not necessarily have to be provided, and a structure without forming the insulating film 348 may be adopted.

[0155] Next, form a conductive film 350 on the insulating film 348. As the conductive film 350, the materials shown in the conductive film 31 5 can be adopted.

[0156] The structure formed on the substrate 342 in the above steps can be formed.

[0157] Next, on the substrate 302 and the substrate 342, more specifically, on the insulating film 31 4, the conductive films 316a and 316b having translucency, and on the conductive film 35 0 formed on the substrate 342, form an alignment film 318 and an alignment film 352 respectively. The alignment film 318 and the alignment film 352 can be formed by using a rubbing method, an optical alignment method, etc. After that, form a liquid crystal layer 320 between the substrate 302 and the substrate 342. As a method for forming the liquid crystal layer 320, a dispenser method (dropping method) or, after bonding the substrate 302 and the substrate 342 together, using capillary action to form it. ​An injection method for injecting liquid crystal can be used.

[0158] In the above steps, the display device shown in Fig. 3(A) can be manufactured.

[0159] <Modification Example 1> The display device shown in Fig. 8(A) is an example in which the oxide semiconductor films 308a and 308b of the transistors 102 and 103 included in the display device described above are formed into a laminated structure of an oxide semiconductor film 388a and an oxide film 3 90a, and an oxide semiconductor film 388b and an oxide film 390b. Therefore, other configurations are the same as those of the transistors 102 and 103, and the previous description can be referred to.

[0160] Here, the details of the oxide semiconductor films 388a and 390a, and the oxide semiconductor films 388 b and the oxide film 390b will be described below.

[0161] The oxide semiconductor films 388a and 388b (hereinafter also referred to as the oxide semiconductor film 388 in the specification) and the oxide films 390a and 390b (hereinafter also referred to as the oxide film 390 in the specification) are preferably made of a metal oxide having at least one same constituent element. Or, the constituent elements of the oxide semiconductor film 388 and the oxide film 390 may be the same, and the compositions of both may be different.

[0162] When the oxide semiconductor film 388 is an In-M-Zn oxide (M is Al, Ga, Ge, Y, Zr, S n, La, Ce or Hf), the atomic ratio of the metal elements of the sputtering target used for forming the In-M-Zn oxide preferably satisfies In≧M and Zn≧M. As such an atomic ratio of the metal elements of the sputtering target, In:M:Z ​​​n = 1:1:1, In:M:Zn = 5:5:6(1:1:1.2), In:M:Zn = 3 :1:2, etc. are preferable. The atomic ratios of the oxide semiconductor film 388 to be formed are respectively allowed to vary by plus or minus 20% of the atomic ratio of the metal elements contained in the above sputtering target as an error.

[0163] When the oxide semiconductor film 388 is an In-M-Zn oxide, the atomic ratio of In to M excluding Zn and O is preferably 25 atomic% or more for In and less than 75 ato mic%, more preferably 34 atomic% or more for In and 66 atomic % or less.

[0164] The oxide semiconductor film 388 has an energy gap of 2 eV or more, preferably 2.5 eV or more , more preferably 3 eV or more. By using such an oxide semiconductor with a wide energy gap, the off-current of the transistor can be reduced.

[0165] The thickness of the oxide semiconductor film 388 is 3 nm or more and 200 nm or less, preferably 3 nm or more and 1 00 nm or less, more preferably 3 nm or more and 50 nm or less.

[0166] The oxide film 390 is typically an In-Ga oxide, an In-Zn oxide, an In-M-Z n oxide (M is Al, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf), and the energy at the lower end of the conduction band is closer to the vacuum level than that of the oxide semiconductor film 388. Typically , the difference between the energy at the lower end of the conduction band of the oxide film 390 and the energy at the lower end of the conduction band of the oxide semiconductor film 388 is 0.05 eV or more, 0.07 eV or more, 0.1 eV or more, or ​0.15 eV or more and 2 eV or less, 1 eV or less, 0.5 eV or less, or 0.4 eV or less That is, the electron affinity of the oxide film 390 and the electron affinity of the oxide semiconductor film 388 are The difference is 0.05 eV or more, 0.07 eV or more, 0.1 eV or more, or 0.15 eV or more. and 2 eV or less, 1 eV or less, 0.5 eV or less, or 0.4 eV or less.

[0167] The oxide film 390 has the above-mentioned element M in a higher atomic ratio than In, and thus has the following effects: (1) The energy gap of the oxide film 390 is increased. (2) (3) To reduce the electron affinity of the oxide film 390. (4) To block impurities from the outside. The insulating property is higher than that of the oxide semiconductor film 388. Since M is a strong metallic element, having a higher atomic ratio than In makes it difficult for oxygen vacancies to occur. It becomes hard.

[0168] When the oxide film 390 is an In-M-Zn oxide, the In and M oxides except for Zn and O are The atomic ratio is preferably less than 50 atomic % for In and 50 atomic % or more for M. More preferably, In is less than 25 atomic % and M is 75 atomic % or more. do.

[0169] The oxide semiconductor film 388 and the oxide film 390 are made of In-M-Zn oxide (M is Al , Ga, Ge, Y, Zr, Sn, La, Ce or Hf), the oxide semiconductor film 388 In comparison, the atomic ratio of M contained in the oxide film 390 is large, and typically, The amount of the atoms contained in the membrane 388 is at least 1.5 times, preferably at least 2 times, The atomic ratio is preferably three times or more higher.

[0170] Also, when the oxide film 390 has an atomic ratio of In:M:Zn = x1:y1:z1 and the oxide semiconductor film 388 has an atomic ratio of In:M:Zn = x2:y2:z2, y1 / x1 is larger than y2 / x2. Preferably, y1 / x1 is 1.5 times or more larger than y2 / x2. More preferably, y1 / x1 is 2 times or more larger than y2 / x2, and even more preferably, y1 / x1 is 3 times or more larger than y2 / x2. At this time, in the oxide semiconductor film 388, when y2 is equal to or more than x2, it is preferable because stable electrical characteristics can be imparted to the transistor using the oxide semiconductor. However, when y2 becomes 3 times or more of x2, the field-effect mobility of the transistor using the oxide semiconductor decreases, so y2 is preferably less than 3 times of x2.

[0171] When the oxide semiconductor film 388 and the oxide film 390 are In-M-Zn oxides, the atomic ratio of the metal elements of the sputtering target used to form the In-M-Zn oxide preferably satisfies M>In and Zn≥M. As the atomic ratio of the metal elements of such a sputtering target, In:Ga:Zn = 1:3:2, In:Ga:Zn = 1:3:3, In:Ga:Zn = 1:3:4, In:Ga:Zn = 1:3:5, In:Ga:Zn = 1:3:6, In:Ga:Zn = 1:3:7, In:Ga:Zn = 1:3:8, In:Ga:Zn = 1:3:9, In:Ga:Zn = 1:3:10, In:Ga:Zn = 1:6:4, In:Ga:Zn = 1:6:5, In:Ga:Zn = 1:6:6, In:Ga:Zn = 1:6:7, In:Ga:Zn = 1:6:8, In:Ga:Zn = 1:6:9, In:Ga:Zn = 1:6:10 are preferable. Note that when using the above sputtering target ​​​​​​​​​​​​​​​​ The atomic ratio of the metal elements contained in the formed oxide semiconductor film 388 and the oxide film 390 is each, including a variation of plus or minus 20% of the atomic ratio of the metal elements contained in the sputtering target as an error.

[0172] Note that the present invention is not limited to these, and those having an appropriate composition may be used according to the semiconductor characteristics and electrical characteristics (field effect mobility, threshold voltage, etc.) of the required transistor. Further, in order to obtain the semiconductor characteristics of the required transistor, the carrier density, impurity concentration, defect density, atomic ratio of metal element to oxygen, interatomic distance, density, etc. of the oxide semiconductor film 388 are made appropriate. It is preferable.

[0173] The oxide film 390 also functions as a damage relaxation film for the oxide semiconductor film 388 when forming the insulating film 312 or the insulating film 314 formed later. The thickness of the oxide film 390 is 3 nm or more and 100 nm or less, preferably 3 nm or more and 50 nm.

[0174] When silicon or carbon, which is one of the group 14 elements, is contained in the oxide semiconductor film 388, oxygen deficiency increases in the oxide semiconductor film 388 and it becomes n-type. For this reason, the concentration of silicon or carbon in the oxide semiconductor film 388, or the concentration of silicon or carbon in the vicinity of the interface between the oxide film 390 and the oxide semiconductor film 388 (the concentration obtained by secondary ion mass spectrometry) is 2×10 atoms / cm or less, preferably 2×10 atoms / cm 18 3 or less. 17 3

[0175] Further, in the oxide semiconductor film 388, the alkali obtained by secondary ion mass spectrometry​​​​​​​​​ The concentration of the metal or alkaline earth metal is 1×10 18 atoms / cm 3 or less, preferably 2×10 16 atoms / cm 3 or less. Alkali metals and alkaline earth metals may generate carriers when combined with an oxide semiconductor, and the off-current of the transistor may increase significantly. Therefore, it is preferable to reduce the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor film 388. When combined with an oxide semiconductor, carriers may be generated, and the off-current of the transistor may increase significantly. Therefore, for this reason, it is preferable to reduce the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor film 388.

[0176] Also, if nitrogen is contained in the oxide semiconductor film 388, electrons as carriers are generated, the carrier density increases, and it is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen tends to have normally-on characteristics. Therefore, in the oxide semiconductor film 388, nitrogen is preferably reduced as much as possible. For example, the nitrogen concentration obtained by secondary ion mass spectrometry is preferably 5×10 atoms / cm or less. 18 atoms / cm 3 or less.

[0177] Note that the oxide semiconductor film 388 and the oxide film 390 are not simply laminated but are fabricated so that a continuous junction (here, a structure in which the energy at the lower end of the conduction band changes continuously between the films) is formed. That is, at the interface of each film, a laminated structure is formed such that there are no impurities that form defect levels such as trap centers or recombination centers for the oxide semiconductor. If impurities are mixed between the laminated oxide semiconductor film 388 and the oxide film 390, the continuity of the energy band is lost, carriers are trapped at the interface, or recombined and disappear. That is, at the interface of each film, a laminated structure is formed such that there are no impurities that form defect levels such as trap centers or recombination centers for the oxide semiconductor. If impurities are mixed between the laminated oxide semiconductor film 388 and the oxide film 390, the continuity of the energy band is lost, carriers are trapped at the interface, or recombined and disappear. If impurities are mixed between the laminated oxide semiconductor film 388 and the oxide film 390, the continuity of the energy band is lost, carriers are trapped at the interface, or recombined and disappear.

[0178] To form a continuous junction, each film needs to be continuously laminated without exposing it to the atmosphere using a multi-chamber film forming apparatus (sputtering apparatus) equipped with a load lock chamber. Each chamber in the sputtering apparatus is preferably evacuated to a high vacuum (to about 5×10 Pa to 1×10 Pa) using an adsorption type vacuum exhaust pump such as a cryopump in order to remove impurities such as water as much as possible for the oxide semiconductor film. Or, it is preferable to combine a turbo molecular pump and a cold trap so that gas, particularly gas containing carbon or hydrogen, does not flow back into the chamber from the exhaust system. Pa~1×10 -7 Pa~1×10 -4 Pa degree). Here, the band structure of the laminated structure included in the transistors 102 and 103 will be described with reference to FIG. 8 (B). .

[0179] FIG. 8(B) schematically shows a part of the band structure included in the transistors 102 and 103. Here, the case where a silicon oxide layer is provided as the insulating film 306 and the insulating film 312 will be described. Note that EcI1 shown in FIG. 8(B) indicates the energy of the lower end of the conduction band of the silicon oxide layer used as the insulating film 306, EcS1 indicates the energy of the lower end of the conduction band of the oxide semiconductor film 388, EcS2 indicates the energy of the lower end of the conduction band of the oxide film 390, and EcI2 indicates the energy of the lower end of the conduction band of the silicon oxide layer used as the insulating film 312. (B).

[0180] As shown in FIG. 8(B), in the oxide semiconductor film 388 and the oxide film 390, the conduction band Here, the case where a silicon oxide layer is provided as the insulating film 306 and the insulating film 312 will be described. Note that EcI1 shown in FIG. 8(B) indicates the energy of the lower end of the conduction band of the silicon oxide layer used as the insulating film 306, EcS1 indicates the energy of the lower end of the conduction band of the oxide semiconductor film 388, EcS2 indicates the energy of the lower end of the conduction band of the oxide film 390, and EcI2 indicates the energy of the lower end of the conduction band of the silicon oxide layer used as the insulating film 312. As shown in FIG. 8(B), in the oxide semiconductor film 388 and the oxide film 390, the conduction band As shown in FIG. 8(B), in the oxide semiconductor film 388 and the oxide film 390, the conduction band As shown in FIG. 8(B), in the oxide semiconductor film 388 and the oxide film 390, the conduction band

[0181] As shown in FIG. 8(B), in the oxide semiconductor film 388 and the oxide film 390, the conduction band The energy at the lower end changes smoothly without a barrier. In other words, it can be said that it changes continuously. This is because the oxide semiconductor film 388 and the oxide film 390 contain common elements and a mixed layer is formed by the mutual movement of oxygen between the oxide semiconductor film 388 and the oxide film 390. It can be said that this is because of this.

[0182] From FIG. 8(B), it can be seen that the oxide semiconductor film 388 becomes a well, and the channel formation region is formed in the oxide semiconductor film 388. Note that since the energy at the lower end of the conduction band of the oxide semiconductor film 388 and the oxide film 390 changes continuously, it can also be said that the oxide semiconductor film 388 and the oxide film 390 are continuously joined.

[0183] As shown in FIG. 8(B), near the interface between the oxide film 390 and the insulating film 312, trapping levels due to impurities or defects such as silicon or carbon, which are constituent elements of the insulating film 312, may be formed. However, by providing the oxide film 390, the oxide semiconductor film 388 can be separated from the trapping levels. However, when the energy difference between EcS1 and EcS2 is small, electrons in the oxide semiconductor film 388 may reach the trapping levels beyond the oxide film 390. When electrons are trapped in the trapping levels, negative fixed charges are formed, and the threshold voltage of the transistor shifts in the positive direction. Therefore, when the energy difference between EcS1 and EcS2 is 0.1 eV or more, preferably 0.15 eV or more, the variation in the threshold voltage of the transistor is reduced, and stable electrical characteristics are obtained, which is preferable.

[0184] Next, the enlarged cross-sectional structure of the transistor 103 and the capacitor element 105 shown in FIG. 8(A) As shown in FIG. 9(A).

[0185] In the cross-sectional view shown in FIG. 9(A), the transistor 103 has an oxide semiconductor film 388b in the channel formation region and an oxide film 390b on the oxide semiconductor film 388b. Note that the oxide semiconductor film 388b is provided over a gate insulating film (here, the insulating film 306). The capacitor element 105 has a conductive film 388c having translucency as one of a pair of electrodes and a conductive film 316b having translucency as the other of the pair of electrodes. Note that the conductive film 388c having translucency is formed on the same surface (the insulating film 306) as the oxide semiconductor film 388b. That is, the conductive film 388c having translucency has the same composition as the oxide semiconductor film 388b. .

[0186]

[0187]

[0188] Next, FIG. 9(B) shows a modified example of the cross-sectional structure of the display device shown in FIG. 9(A).

[0189] In the cross-sectional view shown in FIG. 9(B), the transistor 103 has an oxide semiconductor film 388b in the channel formation region and an oxide film 390b on the oxide semiconductor film 388b. Note that the oxide semiconductor film 388b is provided on a gate insulating film (here, the insulating film 306). The capacitor element 105 has a conductive film 388c having translucency as one of a pair of electrodes and a conductive film 316b having translucency as the other of the pair of electrodes. Note that the conductive film 388c having translucency is formed on the same surface (insulating film 306) as the oxide semiconductor film 388b. That is, the conductive film 388c having translucency has the same composition as the oxide semiconductor film 388b. That is, the conductive film 388c having translucency has the same composition as the oxide semiconductor film 388b. The capacitor element 105 has a conductive film 388c having translucency as one of a pair of electrodes and a conductive film 316b having translucency as the other of the pair of electrodes. Note that the conductive film 388c having translucency is formed on the same surface (insulating film 306) as the oxide semiconductor film 388b. The capacitor element 105 has a conductive film 388c having translucency as one of a pair of electrodes and a conductive film 316b having translucency as the other of the pair of electrodes. Note that the conductive film 388c having translucency is formed on the same surface (insulating film 306) as the oxide semiconductor film 388b. That is, the conductive film 388c having translucency has the same composition as the oxide semiconductor film 388b. 388c is formed on the same surface (insulating film 306) as the oxide semiconductor film 388b. That is, the conductive film 388c having translucency has the same composition as the oxide semiconductor film 388b. That is, the conductive film 388c having translucency has the same composition as the oxide semiconductor film 388b. .

[0190] The cross-sectional structure shown in FIG. 9(B) has a different film thickness of the conductive film 388c having translucency compared to the cross-sectional structure shown in FIG. 9(A). Specifically, in the cross-sectional structure shown in FIG. 9(B), the film thicknesses of the conductive film 388c having translucency and the oxide semiconductor film 388b are substantially the same. In this way, it is also possible to adopt a configuration in which only the oxide film 390c on the conductive film 388c having translucency is removed. Compared with the oxide semiconductor film 388b and the oxide film 390b included in the transistor 103, the transmittance of the capacitor element 105 can be improved by the amount corresponding to the absence of the oxide film 390c. Specifically, in the cross-sectional structure shown in FIG. 9(B), the film thicknesses of the conductive film 388c having translucency and the oxide semiconductor film 388b are substantially the same. In this way, it is also possible to adopt a configuration in which only the oxide film 390c on the conductive film 388c having translucency is removed. Compared with the oxide semiconductor film 388b and the oxide film 390b included in the transistor 103, the transmittance of the capacitor element 105 can be improved by the amount corresponding to the absence of the oxide film 390c. Specifically, in the cross-sectional structure shown in FIG. 9(B), the film thicknesses of the conductive film 388c having translucency and the oxide semiconductor film 388b are substantially the same. In this way, it is also possible to adopt a configuration in which only the oxide film 390c on the conductive film 388c having translucency is removed. Compared with the oxide semiconductor film 388b and the oxide film 390b included in the transistor 103, the transmittance of the capacitor element 105 can be improved by the amount corresponding to the absence of the oxide film 390c. In this way, it is also possible to adopt a configuration in which only the oxide film 390c on the conductive film 388c having translucency is removed. Compared with the oxide semiconductor film 388b and the oxide film 390b included in the transistor 103, the transmittance of the capacitor element 105 can be improved by the amount corresponding to the absence of the oxide film 390c. In this way, it is also possible to adopt a configuration in which only the oxide film 390c on the conductive film 388c having translucency is removed. Compared with the oxide semiconductor film 388b and the oxide film 390b included in the transistor 103, the transmittance of the capacitor element 105 can be improved by the amount corresponding to the absence of the oxide film 390c. Compared with the oxide semiconductor film 388b and the oxide film 390b included in the transistor 103, the transmittance of the capacitor element 105 can be improved by the amount corresponding to the absence of the oxide film 390c. can be improved.

[0191] Next, FIG. 9(C) shows a modified example of the cross-sectional structure of the display device shown in FIG. 9(A).

[0192] In the cross-sectional view shown in FIG. 9(C), the transistor 103 has an oxide semiconductor film in the channel formation region The semiconductor film 388b has an oxide film 390b on the oxide semiconductor film 388b. Note that the oxide semiconductor film 388b is provided on a gate insulating film (here, the insulating film 306). The capacitor element 105 has a conductive film 388c having translucency and an oxide film 3 90c as one of a pair of electrodes, and a conductive film 316b having translucency as the other of the pair of electrodes. Note that the conductive film 388c having translucency is formed on the same surface (insulating film 306) as

[0193] the oxide semiconductor film 388b. Also, in the cross-sectional view shown in FIG. 9(C), the film thickness of the oxide film 390c is thinner than the film thickness of the oxide film 390b. By forming the oxide film 390c with a

[0194] smaller film thickness in this way, the transmittance of the capacitor element 105 can be improved.

[0195] As a method for forming one of the electrodes included in the capacitor element 105 shown in FIGS. 9(A) to 9(C), it can be formed by the following method. In the same process as the oxide semiconductor film 388b and the oxide film 390b included in the transistor 103, the conductive film 388c having translucency and the oxide film 390c are formed. Then, when the opening 372 is formed, the oxide film 390c on the conductive film 388c

[0196] having translucency is removed, whereby the structures shown in FIGS. 9(A) and 9(B) are obtained. Note that FIG. 9(C) can be formed, for example, by setting the etching time Due to the diffusion of hydrogen from 4, the conductivity of the stacked layer of the transparent conductive film 388c and the oxide film 390c is improved, and it becomes a transparent conductive film.

[0197] <Modified Example 2> Here, a modified example of the pixel 301 of the display device shown in FIG. 2(B) will be described with reference to FIG. 10. Note that the pixel 301b of the display device shown in FIG. 10 is a top view of a modified example of the pixel 301 of the display device shown in FIG. 2(B). Thus, regarding the pixel shape of the display device, the implementer can appropriately select an optimal shape.

[0198] In FIG. 10, the conductive film 304c that functions as a scanning line is provided to extend in a direction substantially orthogonal to the signal line (the left - right direction in the figure). The conductive film 310d that functions as a signal line is provided to extend in a direction substantially orthogonal to the scanning line (the up - down direction in the figure). The conductive film 304d that functions as a capacitance line is provided to extend in a direction parallel to the scanning line. Compared with the pixel 301 shown in FIG. 2(B), the pixel 301b shown in FIG. 10 has a shape in which the side parallel to the conductive film 304c that functions as a scanning line is shorter compared to the side parallel to the conductive film 310d that functions as a signal line, the conductive film 304d that functions as a capacitance line is provided to extend in a direction parallel to the conductive film 304c that functions as a scanning line, and the conductive film 304d that functions as a capacitance line is formed simultaneously with the conductive film 304c that functions as a scanning line.

[0199] Also, the transparent conductive film 308c is connected to the conductive film 310f (note that in FIG. 10, the conductive film 310f does not function as a capacitance line). The conductive film 310f is formed simultaneously with the conductive films 310d and 310e.

[0200] Further, on the conductive film 304d, an opening 374d formed in the same manner as the opening 374c is formed. Further, on the conductive film 310f, an opening 374e formed in the same manner as the opening 374c is formed.

[0201] At the opening 374d, the conductive film 304d and the conductive film 316c having translucency are connected. Further, at the opening 374e, the conductive film 310f and the conductive film 316c having translucency are connected. That is, the conductive film 304d and the conductive film 310f are connected by the conductive film 316c having translucency. Therefore, via the conductive film 310f and the conductive film 316c having translucency, the conductive film 308c having translucency is continued to the conductive film 304d that functions as a capacitance line.

[0202] The pixel 301b shown in FIG. 10 has a shape in which the side parallel to the conductive film 304c functioning as a scanning line is shorter than the side parallel to the conductive film 310d functioning as a signal line, and the conductive film 304d functioning as a capacitance line extends in a direction parallel to the conductive film 304c functioning as a scanning line. As a result, it is possible to reduce the area of the conductive film 304d occupied by the pixel, and the aperture ratio can be increased.

[0203] As described above, the configuration shown in the present embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0204] (Embodiment 2) In the present embodiment, an example of an oxide semiconductor film applicable to the transistor and the capacitor element of the display device shown in Embodiment 1 will be described.

[0205] (Crystallinity of Oxide Semiconductor Film) ​​​​​​​​

[0206] Hereinafter, the structure of the oxide semiconductor film will be described.

[0207] The oxide semiconductor film is roughly classified into a non-single-crystalline oxide semiconductor film and a single-crystalline oxide semiconductor film. The non-single-crystalline oxide semiconductor film refers to a CAAC-OS (C Axis Aligned Crystalline Oxide Semiconductor) film, a polycrystalline oxide semiconductor film, a microcrystalline oxide semiconductor film, an amorphous oxide semiconductor film, and the like. stalline Oxide Semiconductor) film, a polycrystalline oxide semiconductor film, a microcrystalline oxide semiconductor film, an amorphous oxide semiconductor film, and the like.

[0208] First, the CAAC-OS film will be described.

[0209] The CAAC-OS film is one of the oxide semiconductor films having a plurality of crystal parts, and most of the crystal parts have a size that can be accommodated within a cube with a side length of less than 100 nm. Therefore, the crystal parts included in the CAAC- OS film also include cases where the side length is less than 10 nm, less than 5 nm, or less than 3 nm and can be accommodated within a cube. Including cases where the size is within a cube with a side length of less than 10 nm, less than 5 nm, or less than 3 nm.

[0210] When the CAAC-OS film is observed by a transmission electron microscope (TEM: Transmission Elec tron Microscope), a clear boundary between crystal parts, that is, a grain boundary (also referred to as a grain boundary) cannot be confirmed. Therefore, it can be said that the C AAC-OS film is less likely to cause a decrease in electron mobility due to grain boundaries.

[0211] When the CAAC-OS film is observed by TEM from a direction roughly parallel to the sample surface (cross-sectional TEM observation), it can be confirmed that metal atoms are arranged in layers in the crystal parts. Metal atoms In each layer of atoms, the film-forming surface (also referred to as the surface to be formed) of the CAAC-OS film or the concave part of the upper surface of the CAAC-OS film or the concave part of the upper surface It has a shape that reflects the convexity and is arranged parallel to the formed surface or the upper surface of the CAAC-OS film.

[0212] In this specification, "parallel" means a state in which two straight lines are arranged at an angle of -10° or more and 10° or less. Therefore, the case of -5° or more and 5° or less is also included. Also, " perpendicular" means a state in which two straight lines are arranged at an angle of 80° or more and 100° or less. Therefore, the case of 85° or more and 95° or less is also included.

[0213] On the other hand, when the CAAC-OS film is observed by TEM from a direction substantially perpendicular to the sample surface (planar TEM observation), it can be confirmed that in the crystal part, metal atoms are arranged in a triangular or hexagonal shape. However, no regularity is seen in the arrangement of metal atoms between different crystal parts.

[0214] From cross-sectional TEM observation and planar TEM observation, it can be seen that the crystal part of the CAAC-OS film has orientation.

[0215] When structural analysis is performed on the CAAC-OS film using an X-ray diffraction (XRD: X-Ray Diffraction) device, for example, in the out-of-plane method analysis of a CAAC-OS film having InGaZnO4 crystals, a peak may appear at around a diffraction angle (2θ) of 31°. Since this peak is attributed to the (009) plane of the InGaZnO4 crystal, it can be confirmed that the crystal of the CAAC-OS film has c-axis orientation and the c-axis is oriented in a direction substantially perpendicular to the formed surface or the upper surface.

[0216] On the other hand, for the CAAC-OS film, in-p In the analysis by the lane method, a peak may appear near 2θ = 56°. This peak is attributed to the (110) plane of the InGaZnO4 crystal. For a single crystal oxide semiconductor film of InGaZnO4, if 2θ is fixed near 56° and the sample is rotated while analyzing (φ scan) with the normal vector of the sample surface as the axis (φ axis), six peaks attributed to crystal planes equivalent to the (110) plane are observed. In contrast, in the case of the CAAC-OS film, no distinct peak appears even when φ scan is performed

[0217] fixed at 2θ near 56°. From the above, it can be seen that in the CAAC-OS film, the a-axis and b-axis orientations are irregular between different crystal parts, but it has c-axis orientation, and the c-axis is oriented in a direction parallel to the normal vector of the formed surface or the upper surface.

[0218] Note that the crystal parts are formed when the CAAC-OS film is deposited or when crystallization treatment such as heat treatment is performed. As described above, the c-axis of the crystal is oriented in a direction parallel to the normal vector of the formed surface or the upper surface of the CAAC-OS film. Therefore, for example, when the shape of the CAAC-OS film is changed by etching or the like, the c-axis of the crystal may not be

[0219] parallel to the normal vector of the formed surface or the upper surface of the CAAC-OS film. Also, the crystallinity in the CAAC-OS film does not have to be uniform. For example, when the crystal parts of the CAAC-OS film are formed by crystal growth from near the upper When impurities are added to the AC-OS film, the crystallinity of the region where the impurities are added changes, and regions with different degrees of crystallinity may be partially formed.

[0220] In addition, in the out-of-plane analysis of the CAAC-OS film having InGaZnO4 crystals, in addition to the peak at around 2θ = 31°, a peak may also appear at around 2θ = 36°. In the case where a peak appears at around 2θ = 36°, it indicates that a part of the CAAC-OS film contains crystals having no c-axis orientation. The CAAC-OS film preferably shows a peak at around 2θ = 31° and does not show a peak at around 2θ = 36°.

[0221] The CAAC-OS film is an oxide semiconductor film with a low impurity concentration. Impurities are elements other than the main components of the oxide semiconductor film, such as hydrogen, carbon, silicon, and transition metal elements. In particular, elements such as silicon, which have a stronger binding force with oxygen than the metal elements constituting the oxide semiconductor film, disrupt the atomic arrangement of the oxide semiconductor film by taking oxygen from the oxide semiconductor film, which is a factor in reducing the crystallinity. In addition, heavy metals such as iron and nickel, argon, carbon dioxide, etc., have a large atomic radius (or molecular radius), so when contained inside the oxide semiconductor film, they disrupt the atomic arrangement of the oxide semiconductor film, which is a factor in reducing the crystallinity. Note that impurities contained in the oxide semiconductor film may be carrier traps or carrier generation sources.

[0222] In addition, the CAAC-OS film is an oxide semiconductor film with a low density of defect levels.

[0223] In addition, a transistor using the CAAC-OS film has little variation in electrical characteristics due to irradiation with visible light or ultraviolet light.

[0224] ​​​​​​​​​​​​ Next, the microcrystalline oxide semiconductor film will be described.

[0225] In the observation image by TEM, it may not be possible to clearly confirm the crystalline part in the microcrystalline oxide semiconductor film. The crystalline parts contained in the microcrystalline oxide semiconductor film are often 1 nm or more and 100 nm or less, or 1 nm or more and 10 nm or less in size. In particular, nanocrystals (nc: nanocrystalline) that are microcrystals of 1 nm or more and 10 nm or less, or 1 nm or more and 3 nm or less, are present in the oxide semiconductor film, which is called an nc-OS (nanocrystalline Oxide Semiconductor) film. Also, in the observation image by TEM, for example, it may not be possible to clearly confirm the grain boundaries in the nc-OS film. m or less, or 1 nm or more and 3 nm or less, are present in the oxide semiconductor film, which is called an nc-OS (nanocrystalline Oxide Semiconductor) film. Also, in the observation image by TEM, for example, it may not be possible to clearly confirm the grain boundaries in the nc-OS film. xide Semiconductor) film. Also, the nc-OS film may not be able to clearly confirm the grain boundaries in the observation image by TEM, for example. In the observation image by TEM, for example, it may not be possible to clearly confirm the grain boundaries in the nc-OS film.

[0226] The nc-OS film has periodicity in the atomic arrangement in a minute region (for example, a region of 1 nm or more and 10 nm or less, particularly a region of 1 nm or more and 3 nm or less). Also, the nc-OS film has no regularity in the crystal orientation between different crystalline parts. Therefore, no orientation is observed in the entire film. crystalline parts. Therefore, no orientation is observed in the entire film. Therefore, depending on the analysis method, the nc-OS film may not be distinguishable from the amorphous oxide semiconductor film. For example, when performing structural analysis on the nc-OS film using an XRD apparatus using X-rays with a diameter larger than that of the crystalline part, no peak indicating the crystal plane is detected in the analysis by the out-of-plane method. Also, when performing electron beam diffraction (also called limited field of view electron beam diffraction) on the nc-OS film using an electron beam with a diameter larger than that of the crystalline part (for example 50 nm or more), a diffraction image such as a halo pattern is observed. On the other hand, when performing electron beam diffraction on the nc-OS film using an electron beam with a diameter close to or smaller than that of the crystalline part (for example 50 nm or more), a diffraction image such as a halo pattern is observed. On the other hand, when performing electron beam diffraction on the nc-OS film using an electron beam with a diameter close to or smaller than that of the crystalline part (for example 1 nm or more and 30 nm or less), a diffraction image such as a halo pattern is observed. On the other hand, when performing electron beam diffraction on the nc-OS film using an electron beam with a diameter close to or smaller than that of the crystalline part (for example 1 nm or more and 30 nm or less), a diffraction image such as a halo pattern is observed. On the other hand, when performing electron beam diffraction on the nc-OS film using an electron beam with a diameter close to or smaller than that of the crystalline part (for example When performing sub-beam diffraction (also referred to as nano-beam electron diffraction), spots are observed. Also, When performing nano-beam electron diffraction on the nc-OS film, regions with high luminance may be observed in a circular (ring-shaped) pattern. Also, when performing nano-beam electron diffraction on the nc-OS film, multiple spots may be observed within the ring-shaped region.

[0227] The nc-OS film is an oxide semiconductor film with higher regularity than an amorphous oxide semiconductor film. Therefore, the nc-OS film has a lower density of defect energy levels than an amorphous oxide semiconductor film. However, in the nc-OS film, no regularity is observed in the crystal orientation between different crystal parts. Therefore, the nc-OS film has a higher density of defect energy levels than the CAAC-OS film.

[0228] Note that the oxide semiconductor film may be, for example, a laminated film having two or more of an amorphous oxide semiconductor film, a microcrystalline oxide semiconductor film, and a CAAC-OS film.

[0229] <Method for forming a CAAC-OS film> The CAAC-OS film is formed, for example, by a sputtering method using a target for oxide semiconductor sputtering that is polycrystalline. When ions collide with the sputtering target, the crystal regions contained in the sputtering target cleave from the a-b plane and are peeled off as flat plate-shaped or pellet-shaped sputtering particles having a plane parallel to the a-b plane. In this case, the CAAC-OS film can be formed by the flat plate-shaped or pellet-shaped sputtering particles reaching the substrate while maintaining their crystal state.

[0230] The flat plate-shaped or pellet-shaped sputtering particles are, for example, equivalent to a circle of a plane parallel to the a-b plane. The diameter is 3 nm or more and 10 nm or less, and the thickness (the length in the direction perpendicular to the a-b plane) is 0.7 nm or more and less than 1 nm. Note that the flat or pellet-shaped sputtering particles may have a face parallel to the a-b plane where the equivalent circle diameter of the face is an equilateral triangle or a regular hexagon. Here, the equivalent circle diameter of the face refers to the diameter of a perfect circle equal to the area of the face .

[0231] In addition, in order to form a CAAC-OS film, it is preferable to apply the following conditions

[0232] By increasing the substrate temperature during film formation, migration of sputtering particles occurs after reaching the substrate . Specifically, the film is formed with the substrate temperature being 100°C or more and 740°C or less, preferably 200°C or more and 500°C or less. By increasing the substrate temperature during film formation, when flat or pellet-shaped sputtering particles reach the substrate, migration occurs on the substrate, and the flat face of the sputtering particles adheres to the substrate . At this time, since the sputtering particles are positively charged, the sputtering particles adhere to the substrate while repelling each other, so the sputtering particles do not become unevenly overlapped due to bias, and a CAAC-OS film with uniform thickness can be formed . . .

[0233] By reducing the impurity incorporation during film formation, it is possible to suppress the breakdown of the crystal state due to impurities . For example, the impurity concentration (such as hydrogen, water, carbon dioxide, and nitrogen) present in the film formation chamber may be reduced . Also, the impurity concentration in the film formation gas may be reduced. Specifically, a film formation gas with a dew point of -80°C or lower, preferably -100°C or lower, is used

[0234] In addition, by increasing the oxygen ratio in the film formation gas and optimizing the power, plasma damage during film formation can be reduced ​​​​​It is preferable to reduce the Ge. The oxygen ratio in the film-forming gas is 30% by volume or more, preferably 100 % by volume.

[0235] Alternatively, the CAAC-OS film is formed by the following method.

[0236] First, a first oxide semiconductor film is formed to a thickness of 1 nm or more and less than 10 nm. The first oxide semiconductor film is formed using a sputtering method. Specifically, the substrate temperature is 100°C or more and 500°C or less, preferably 150°C or more and 450°C or less, and the oxygen ratio in the film-forming gas is 30 % by volume or more, preferably 100% by volume for film formation.

[0237] Next, a heat treatment is performed to obtain a first CAAC-OS film with high crystallinity from the first oxide semiconductor film. The temperature of the heat treatment is 350°C or more and 740°C or less, preferably 450°C or more and 650 °C or less. Also, the time of the heat treatment is 1 minute or more and 24 hours or less, preferably 6 minutes or more and 4 hours or less. Further, the heat treatment may be performed in an inert atmosphere or an oxidizing atmosphere. Preferably, after performing the heat treatment in an inert atmosphere, the heat treatment is performed in an oxidizing atmosphere. By the heat treatment in the inert atmosphere, the impurity concentration of the first oxide semiconductor film can be reduced in a short time. On the other hand, oxygen vacancies may be generated in the first oxide semiconductor film by the heat treatment in the inert atmosphere. In that case, the oxygen vacancies can be reduced by the heat treatment in the oxidizing atmosphere. Note that the heat treatment may be performed under a reduced pressure of 1000 Pa or less, 100 Pa or less, 10 Pa or less, or 1 Pa or less. Under reduced pressure, the impurity concentration of the first oxide semiconductor film can be reduced in an even shorter time.

[0238] ​​The first oxide semiconductor film has a thickness of 1 nm or more and less than 10 nm, and can be easily crystallized by heat treatment as compared with the case where the thickness is 1 0 nm or more.

[0239] Next, a second oxide semiconductor film having the same composition as the first oxide semiconductor film is formed with a thickness of 10 nm or more and 5 0 nm or less. The second oxide semiconductor film is formed by a sputtering method. Specifically, the substrate temperature is 100°C or more and 500°C or less, preferably 150°C or more and 450 °C or less, and the oxygen ratio in the film-forming gas is 30 vol% or more, preferably 100 vol%, to form the film.

[0240] Next, heat treatment is performed to cause solid-phase growth of the second oxide semiconductor film from the first CAAC-OS film, thereby obtaining a second CAAC-OS film with high crystallinity. The temperature of the heat treatment is 350 °C or more and 740°C or less, preferably 450°C or more and 650°C or less. Also, the time of the heat treatment is 1 minute or more and 24 hours or less, preferably 6 minutes or more and 4 hours or less. Further, the heat treatment may be performed in an inert atmosphere or an oxidizing atmosphere. Preferably, heat treatment is performed in an inert atmosphere and then in an oxidizing atmosphere. By the heat treatment in the inert atmosphere, the impurity concentration of the second oxide semiconductor film can be reduced in a short time. On the other hand, oxygen deficiency may be generated in the second oxide semiconductor film by the heat treatment in the inert atmosphere. In that case, the oxygen deficiency can be reduced by the heat treatment in the oxidizing atmosphere. Note that the heat treatment may be performed under a reduced pressure of 1 000 Pa or less, 100 Pa or less, 10 Pa or less, or 1 Pa or less. Under reduced pressure, the impurity concentration of the second oxide semiconductor film can be reduced even more in a short time.

[0241] In this way, a CAAC-OS film with a total thickness of 10 nm or more can be formed. The CAAC-OS film can be suitably used as an oxide semiconductor film in the oxide stack.

[0242] Next, for example, when the surface to be formed is at a low temperature (e.g., less than 130 °C, less than 100 °C, less than 70 °C, or about room temperature (20 °C to 25 °C)) due to not heating the substrate, etc., a method for forming an oxide film will be described. When the surface to be formed is at a low temperature, sputtered particles pour irregularly onto the film-forming surface. Since the sputtered particles, for example, do not migrate, they are deposited disorderly, including in regions where other sputtered particles have already been deposited. That is, the oxide film obtained by deposition may not have a uniform thickness and may have a disordered crystal orientation. The oxide film obtained in this way has crystal parts (nanocrystals) in order to maintain the crystallinity of the sputtered particles to some extent.

[0243] When the surface to be formed is at a low temperature, sputtered particles pour irregularly onto the film-forming surface. Since the sputtered particles, for example, do not migrate, they are deposited disorderly, including in regions where other sputtered particles have already been deposited. That is, the oxide film obtained by deposition may not have a uniform thickness and may have a disordered crystal orientation. The oxide film obtained in this way has crystal parts (nanocrystals) in order to maintain the crystallinity of the sputtered particles to some extent. For example, since they do not migrate, they are deposited disorderly, including in regions where other sputtered particles have already been deposited. That is, the oxide film obtained by deposition may not have a uniform thickness and may have a disordered crystal orientation. The oxide film obtained in this way has crystal parts (nanocrystals) in order to maintain the crystallinity of the sputtered particles to some extent.

[0244] Also, for example, when the pressure during film formation is high, the frequency of collision between the flying sputtered particles and other particles (such as atoms, molecules, ions, radicals, etc.) such as argon increases. The sputtered particles may have their crystal structure disrupted by colliding with other particles (re-sputtered) during flight. For example, the sputtered particles may not be able to maintain a flat plate shape due to colliding with other particles and may be subdivided (e.g., into individual atoms). At this time, an amorphous oxide film may be formed by each atom separated from the sputtered particles depositing on the surface to be formed. For example, when the pressure during film formation is high, the frequency of collision between the flying sputtered particles and other particles (such as atoms, molecules, ions, radicals, etc.) such as argon increases. The sputtered particles may have their crystal structure disrupted by colliding with other particles (re-sputtered) during flight. For example, the sputtered particles may not be able to maintain a flat plate shape due to colliding with other particles and may be subdivided (e.g., into individual atoms). At this time, an amorphous oxide film may be formed by each atom separated from the sputtered particles depositing on the surface to be formed.

[0245] Further, instead of the sputtering method using a target having a polycrystalline oxide as a starting point, in the case of a method of forming a film using a liquid, or in the case of a method of forming a film by vaporizing a solid such as a target, since they fly in a state separated into each atom and deposit on the surface to be formed, an amorphous oxide film may be formed. Further, for example, in the laser ablation method, atoms, molecules, ions, radicals, clusters, etc. emitted from the target fly and deposit on the surface to be formed, so an amorphous oxide film may be formed.

[0246] The oxide semiconductor film included in the transistor and the capacitor element of the display device according to one aspect of the present invention may be any of the above-described oxide semiconductor films in any crystal state. Further, when including an oxide semiconductor film having a stacked structure, the crystal states of the respective oxide semiconductor films may be different. However, it is preferable to apply a CAAC-OS film to the oxide semiconductor film that functions as the channel formation region of the transistor. Further, since the oxide semiconductor film (a conductive film having translucency) included in the capacitor element has a higher impurity concentration than the oxide semiconductor film included in the transistor, the crystallinity may be reduced.

[0247] As described above, the configuration shown in the present embodiment can be used in appropriate combination with the configuration shown in other embodiments.

[0248] (Embodiment 3) In the present embodiment, a display module and an electronic device that can use the display device according to one aspect of the present invention will be described with reference to FIGS. 11 and 12.

[0249] The display module 8000 shown in FIG. 11 includes an upper cover 8001 and a lower cover 8002 Between them, there are a touch panel 8004 connected to the FPC8003, a display panel 8006 connected to the FPC8005, a backlight unit 8007, a frame 8009, a printed circuit board 8010, and a battery 8011. The upper cover 8001 and the lower cover 8002 can have their shapes and dimensions appropriately changed according to the sizes of the touch panel 8004 and the display panel 8006. The touch panel 8004 can be used by superimposing a resistive film type or a capacitive type touch panel on the display panel 8006. Also, it is possible to provide a touch panel function on the counter substrate (sealing substrate) of the display panel 8006. Further, it is possible to provide an optical sensor in each pixel of the display panel 8006 to make it an optical touch panel.

[0250] The display device according to one aspect of the present invention can be used, for example, for the display panel 8006.

[0251] The upper cover 8001 and the lower cover 8002 can have their shapes and dimensions appropriately changed according to the sizes of the touch panel 8004 and the display panel 8006. The upper cover 8001 and the lower cover 8002 can have their shapes and dimensions appropriately changed according to the sizes of the touch panel 8004 and the display panel 8006.

[0252] The touch panel 8004 can be used by superimposing a resistive film type or a capacitive type touch panel on the display panel 8006. Also, it is possible to provide a touch panel function on the counter substrate (sealing substrate) of the display panel 8006. Further, it is possible to provide an optical sensor in each pixel of the display panel 8006 to make it an optical touch panel. The touch panel 8004 can be used by superimposing a resistive film type or a capacitive type touch panel on the display panel 8006. Also, it is possible to provide a touch panel function on the counter substrate (sealing substrate) of the display panel 8006. Further, it is possible to provide an optical sensor in each pixel of the display panel 8006 to make it an optical touch panel. The upper cover 8001 and the lower cover 8002 can have their shapes and dimensions appropriately changed according to the sizes of the touch panel 8004 and the display panel 8006. The upper cover 8001 and the lower cover 8002 can have their shapes and dimensions appropriately changed according to the sizes of the touch panel 8004 and the display panel 8006.

[0253] The backlight unit 8007 has a light source 8008. The light source 8008 can be provided at the end of the backlight unit 8007, and a configuration using a light diffusing plate may be adopted. The backlight unit 8007 has a light source 8008. The light source 8008 can be provided at the end of the backlight unit 8007, and a configuration using a light diffusing plate may be adopted.

[0254] The frame 8009 has a function as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed circuit board 8010 in addition to the protection function of the display panel 8006. Also, the frame 8009 may have a function as a heat dissipation plate. The frame 8009 has a function as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed circuit board 8010 in addition to the protection function of the display panel 8006. Also, the frame 8009 may have a function as a heat dissipation plate. The frame 8009 has a function as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed circuit board 8010 in addition to the protection function of the display panel 8006. Also, the frame 8009 may have a function as a heat dissipation plate.

[0255] The printed circuit board 8010 has a power supply circuit and a signal processing circuit for outputting a video signal and a clock signal. As the power supply for supplying power to the power supply circuit, an external commercial power supply can be used. The printed circuit board 8010 has a power supply circuit and a signal processing circuit for outputting a video signal and a clock signal. As the power supply for supplying power to the power supply circuit, an external commercial power supply can be used. It may also be a power source using a separately provided battery 8011. The battery 801 1 can be omitted when using a commercial power source.

[0256] In addition, members such as a polarizing plate, a retardation plate, and a prism sheet may be additionally provided to the display module 8000.

[0257] Figs. 12(A) to 12(H) are diagrams showing electronic devices. These electronic devices include a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004, operation keys 50 05 (including a power switch or an operation switch), connection terminals 5006, a sensor 5007 ( having a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance , sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays), a microphone 5008, etc. It can have.

[0258] Fig. 12(A) is a mobile computer, and in addition to the above, it can have a switch 5009 , an infrared port 5010, etc. Fig. 12(B) is a portable image playback device equipped with a recording medium (for example, a DVD playback device), and in addition to the above, a second display unit 5002, a recording medium reading unit 5011, etc. Fig. 12(C) is a go ogle-type display, and in addition to the above, it can have a second display unit 5002, a support unit 5012 , earphones 5013, etc. Fig. 12(D) is a portable game machine, and in addition to the above, it can have a recording medium reading unit 5011, etc. Fig. 12(E) is a digital camera with a TV receiving function, and in addition to the above, an antenna 5014, a system LSI 5015, etc. Fig. 12(F) is a digital video camera, and in addition to the above, it can have a recording medium reading unit 5011, etc. Fig. 12(G) is a portable information terminal, and in addition to the above, it can have a touch panel 5016, a communication unit 5017, etc. Fig. 12(H) is a It can have a shutter button 5015, an image receiving unit 5016, etc. FIG. 12(F) is a portable game machine, and in addition to the above-described components, it can have a second display unit 5002, a recording medium reading unit 5011 , etc. FIG. 12(G) is a television receiver, and in addition to the above-described components, it can have a tuner, an image processing unit, etc. FIG. 12(H) is a portable television receiver , and in addition to the above-described components, it can have a charger 5017 capable of transmitting and receiving signals, etc.

[0259] The electronic devices shown in FIGS. 12(A) to 12(H) can have various functions. For example, a function of displaying various information (such as still images, moving images, text images, etc.) on the display unit, a touch panel function, a function of displaying a calendar, date, or time, etc., a function of controlling processing by various software (programs), a wireless communication function, a function of connecting to various computer networks using the wireless communication function, a function of transmitting or receiving various data using the wireless communication function, a function of reading out a program or data recorded on a recording medium and displaying it on the display unit, etc. can be provided. Furthermore, in an electronic device having a plurality of display units, a function of mainly displaying image information on one display unit and mainly displaying character information on another display unit, or a function of displaying a three-dimensional image by displaying an image considering parallax on a plurality of display units, etc. can be provided. Furthermore, in an electronic device having an image receiving unit, a function of taking a still image, a function of taking a moving image, a function of automatically or manually correcting the taken image, a function of saving the taken image on a recording medium (external or built into the camera), a function of displaying the taken image on the display unit, etc. can be provided. Note that FIGS. 12(A) to 1 ​​​​​​The functions that the electronic device shown in 2(H) can have are not limited to these, and it can have various functions. It can have.

[0260] The electronic device described in this embodiment is characterized by having a display unit for displaying some information. It is characterized by that.

[0261] The configuration shown in this embodiment can be used in appropriate combination with the configuration shown in other embodiments. It can be.

Explanation of Reference Numerals

[0262] 100 Pixel portion 102 Transistor 103 Transistor 104 Scanning line driving circuit 105 Capacitive element 106 Signal line driving circuit 107 Scanning line 108 Liquid crystal element 109 Signal line 115 Capacitive line 301 Pixel 301b Pixel 302 Substrate 304a Conductive film 304b Conductive film 304c Conductive film 304d Conductive film 305 Insulating film 306 Insulating film 307 Oxide semiconductor film 308a Oxide semiconductor film 308b Oxide semiconductor film 308c Conductive film 308d Oxide semiconductor film 309 Conductive film 310a Conductive film 310b Conductive film 310c Conductive film 310d Conductive film 310e Conductive film 310f Conductive film 311 Insulating film 312 Insulating film 313 Insulating film 314 Insulating film 315 Conductive film 316a Conductive film 316b Conductive film 316c Conductive film 318 Alignment film 320 Liquid crystal layer 342 Substrate 344 Light-shielding film 346 Colored film 348 Insulating film 350 Conductive film 352 Alignment film 372 Opening 374a Opening 374b Opening 374c Opening 374d Opening 374e Opening 388 Oxide semiconductor film 388a Oxide semiconductor film 388b Oxide semiconductor film 388c Conductive film 390 Oxide film 390a Oxide film 390b Oxide film 390c Oxide film 5000 Housing 5001 Display unit 5002 Display unit 5003 Speaker 5004 LED lamp 5005 Operation key 5006 Connection terminal 5007 Sensor 5008 Microphone 5009 Switch 5010 Infrared port 5011 Recording medium reading unit 5012 Support part 5013 Earphone 5014 Antenna 5015 Shutter button 5016 Image receiving unit 5017 Charger 8000 Display Module 8001 Upper Cover 8002 Lower Cover 8003 FPC 8004 Touch Panel 8005 FPC 8006 Display Panel 8007 Backlight Unit 8008 Light Source 8009 Frame 8010 Printed Circuit Board 8011 Battery

Claims

1. A scanning line driver circuit is provided. the scanning line driver circuit includes a first conductive film, a second conductive film, a first oxide semiconductor film, a second oxide semiconductor film, and a third conductive film; The third conductive film has a region that functions as a gate electrode, In a plan view, the first conductive film has a first region, a second region, and a third region; In a plan view, the first region, the second region, and the third region are regions branched from a trunk region and arranged to extend along a first direction, In a plan view, the second conductive film has a fourth region and a fifth region, In a plan view, the fourth region and the fifth region are regions branched from a trunk region and are arranged to extend along a second direction opposite to the first direction, The fourth region is disposed between the first region and the second region in a plan view, The fifth region is disposed between the second region and the third region in a plan view, In a plan view, the first oxide semiconductor film is disposed so as to extend along a third direction intersecting the first direction, the second oxide semiconductor film is disposed at an interval from the first oxide semiconductor film in a plan view and extends along the third direction; the first region has a region overlapping with the first oxide semiconductor film and being in contact with the first oxide semiconductor film; the first region has a region overlapping with the second oxide semiconductor film and being in contact with the second oxide semiconductor film; the second region has a region overlapping with the first oxide semiconductor film and being in contact with the first oxide semiconductor film; the second region has a region overlapping with the second oxide semiconductor film and being in contact with the second oxide semiconductor film; the third region has a region overlapping with the first oxide semiconductor film and being in contact with the first oxide semiconductor film; the third region has a region overlapping with the second oxide semiconductor film and being in contact with the second oxide semiconductor film; the fourth region has a region overlapping with the first oxide semiconductor film and in contact with the first oxide semiconductor film, the fourth region has a region overlapping with the second oxide semiconductor film and being in contact with the second oxide semiconductor film, the fifth region has a region overlapping with the first oxide semiconductor film and being in contact with the first oxide semiconductor film, the fifth region has a region overlapping with the second oxide semiconductor film and being in contact with the second oxide semiconductor film, In a plan view, the first oxide semiconductor film has a region sandwiched between the first region and the fourth region, a region sandwiched between the second region and the fourth region, a region sandwiched between the second region and the fifth region, and a region sandwiched between the third region and the fifth region, In a plan view, the second oxide semiconductor film has a region sandwiched between the first region and the fourth region, a region sandwiched between the second region and the fourth region, a region sandwiched between the second region and the fifth region, and a region sandwiched between the third region and the fifth region, the third conductive film has a region overlapping with the entire first oxide semiconductor film and a region overlapping with the entire second oxide semiconductor film in a plan view.

2. In claim 1, the first oxide semiconductor film and the second oxide semiconductor film each contain In, Zn, and M (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, or Hf).

Images