Display device

Abstract

To provide a display device that has high aperture ratio and comprises a capacitive element capable of increasing a capacitance value, and also can achieve a narrow frame.SOLUTION: A transistor comprises a gate electrode on a substrate, an oxide semiconductor film overlapping the gate electrode, a gate insulating film in contact with one face of the oxide semiconductor film, and a pair of conductive films in contact with the oxide semiconductor film. A capacitive element comprises a metal oxide film on the gate insulating film and in contact with one of the pair of conductive films, an inorganic insulating film, and a first translucent conductive film on the inorganic insulating film. A pixel electrode is formed of a second translucent conductive film and is in contact with one of the pair of conductive films. A first gate line, which also serves as a gate electrode, is connected so as to select three sub-pixels among four sub-pixels, and a second gate line is connected so as to select remaining sub-pixels and also select one sub-pixel of a next line.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One aspect of the present invention relates to a display device. In particular, one aspect of the present invention relates to a display device having a liquid crystal element as a display element thereof.

[0002] Note that the present invention is not limited to the above technical field. The technical field of the invention disclosed in this specification and the like is related to an object, a method, or a manufacturing method. Or, the present invention relates to a process, a machine a manufacture, or a composition of matter. Therefore, more specifically, as the technical field of one aspect of the present invention disclosed in this specification, semiconductor devices, display devices, light-emitting devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof can be cited as an example.

Background Art

[0003] In recent years, with respect to a configuration that performs color display using sub-pixels provided with color filters of three primary colors, namely RGB (red, green, and blue), a display device has been proposed in which a sub-pixel of W (white) is added to RGB to achieve low power consumption or improved brightness (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By adding a W sub-pixel to a sub-pixel provided with an RGB (red, green, and blue) color filter, each The number of wirings for controlling sub-pixels increases. When the number of wirings increases, it is necessary to increase the circuit area for driving the wirings, so it becomes difficult to reduce the bezel width in a configuration with a built-in circuit for driving.

[0006] Alternatively, the number of sub-pixels constituting a pixel increases, so that the area per sub-pixel becomes small. Therefore, it becomes difficult to secure the necessary capacitance value in the capacitance element or to reduce the aperture ratio.

[0007] Therefore, one aspect of the present invention is to provide a novel configuration display device or the like that can suppress an increase in the number of wirings even when the number of sub-pixels increases. Or, one aspect of the present invention is to provide a novel configuration display device or the like that can achieve a narrow bezel width as one of the problems. Or, one aspect of the present invention is to provide a novel configuration display device or the like that can suppress a decrease in the aperture ratio as one of the problems. Or, one aspect of the present invention is to provide a novel configuration display device or the like that can secure the necessary capacitance value in the capacitance element as one of the problems. Or, one aspect of the present invention is to provide a novel configuration display device or the like with excellent display quality as one of the problems. Also, one aspect of the present invention is to provide a novel display device or the like as one of the problems.

[0008] Note that the problems of the present invention are not limited to the problems listed above. The problems listed above do not prevent the existence of other problems. Other problems are the problems not mentioned in this item as described below. The problems not mentioned in this item can be derived by those skilled in the art from the descriptions in the specification or drawings, etc., and can be appropriately extracted from these descriptions. Note that one aspect of the present invention is at least one of the problems listed above and / or other problems. ​​​​​​​​​​​​​ It is to solve this problem.

Means for Solving the Problem

[0009] One aspect of the present invention has a first pixel having first to fourth sub-pixels and a second pixel having first to fourth sub-pixels provided in the next row of the first pixel, and a first wiring for supplying a signal for selecting the first to third sub-pixels of the first pixel, and a second wiring for selecting the fourth sub-pixel of the first pixel, and the second wiring is a wiring for selecting the fourth sub-pixel of the second pixel, which is a display device.

[0010] Another aspect of the present invention has a first pixel having first to fourth sub-pixels and a second pixel having first to fourth sub-pixels provided in the next row of the first pixel, and a first wiring for supplying a signal for selecting the first to third sub-pixels of the first pixel, a second wiring for selecting the fourth sub-pixel of the first pixel, and a third wiring for selecting the first to third sub-pixels of the second pixel, and the second wiring is a wiring for selecting the fourth sub-pixel of the second pixel, which is a display device.

[0011]

Advantages of the Invention

[0011] According to one aspect of the present invention, it is possible to provide a novel configuration display device or the like that can suppress an increase in the number of wirings even when the number of sub-pixels increases. Or, one aspect of the present invention can provide a novel configuration display device or the like that can achieve a narrow bezel. Or, one aspect of the present invention can provide a novel configuration display device or the like that can suppress a decrease in the aperture ratio. Or, one aspect of the present invention can provide a novel configuration display device or the like that can secure the necessary capacitance value in a capacitive element. ​​​​It can be used. Or, one aspect of the present invention can provide a display device or the like with excellent display quality and a novel configuration. Or, one aspect of the present invention can provide a novel display device or the like. It can be used. Or, one aspect of the present invention can provide a display device or the like with excellent display quality and a novel configuration. Or, one aspect of the present invention can provide a novel display device or the like. It can be provided.

[0012] Note that the effects of the present invention are not limited to the effects listed above. The effects listed above do not prevent the existence of other effects. Other effects are the effects not mentioned in this item and described below. Effects not mentioned in this item can be derived by those skilled in the art from the descriptions in the specification, drawings, etc., and can be appropriately extracted from these descriptions. Note that one aspect of the present invention has at least one of the effects listed above and / or other effects. Therefore, one aspect of the present invention may not have the effects listed above in some cases. Note that the effects of the present invention are not limited to the effects listed above. The effects listed above do not prevent the existence of other effects. Other effects are the effects not mentioned in this item and described below. Effects not mentioned in this item can be derived by those skilled in the art from the descriptions in the specification, drawings, etc., and can be appropriately extracted from these descriptions. Note that one aspect of the present invention has at least one of the effects listed above and / or other effects. Therefore, one aspect of the present invention may not have the effects listed above in some cases. Note that the effects of the present invention are not limited to the effects listed above. The effects listed above do not prevent the existence of other effects. Other effects are the effects not mentioned in this item and described below. Effects not mentioned in this item can be derived by those skilled in the art from the descriptions in the specification, drawings, etc., and can be appropriately extracted from these descriptions. Note that one aspect of the present invention has at least one of the effects listed above and / or other effects. Therefore, one aspect of the present invention may not have the effects listed above in some cases. Note that the effects of the present invention are not limited to the effects listed above. The effects listed above do not prevent the existence of other effects. Other effects are the effects not mentioned in this item and described below. Effects not mentioned in this item can be derived by those skilled in the art from the descriptions in the specification, drawings, etc., and can be appropriately extracted from these descriptions. Note that one aspect of the present invention has at least one of the effects listed above and / or other effects. Therefore, one aspect of the present invention may not have the effects listed above in some cases. Note that one aspect of the present invention has at least one of the effects listed above and / or other effects. Therefore, one aspect of the present invention may not have the effects listed above in some cases. Note that one aspect of the present invention has at least one of the effects listed above and / or other effects. Therefore, one aspect of the present invention may not have the effects listed above in some cases. It may not have the effects listed above in some cases.

Brief Description of the Drawings

[0013]

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Best Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments will be described with reference to the drawings. However, the embodiments can be implemented in many different ways, and it will be easily understood by those skilled in the art that the form and details can be variously changed without departing from the spirit and its scope. Therefore, the present invention is not construed as being limited to the description of the following embodiments. In the configuration of the invention described below, reference numerals indicating the same object are common among different drawings.

[0015] Also, in the drawings, there are cases where the size, layer thickness, or area is exaggerated for clarity. Therefore, it is not necessarily limited to that scale. The drawings are schematic illustrations of ideal examples and are not limited to the shapes or values shown in the drawings. For example, it is possible to include variations in signals, voltages, or currents due to noise, or variations in signals, voltages, or currents due to timing deviations.

[0016] Also, in this specification and the like, a transistor is an element having at least three terminals including a gate, a drain, and a source. And there is a channel region between the drain (drain terminal, drain region, or drain electrode) and the source (source terminal, source region, or source electrode), and current can flow through the drain, the channel region, and the source.

[0017] Here, since the source and the drain change depending on the structure or operating conditions of the transistor, etc., it is difficult to limit which is the source or the drain. Therefore, the source and ​​​The part that functions as a source and the part that functions as a drain are not called a source or a drain, One of the source and the drain may be denoted as the first terminal, and the other of the source and the drain may be denoted as the second terminal.

[0018] It should be noted that the ordinal numbers "first", "second", and "third" used in this specification are added to avoid confusion of components, and it is noted that they are not numerically limiting.

[0019] In this specification, "A and B are connected" means that not only A and B are directly connected, but also those that are electrically connected are included. Here, "A and B are electrically connected" means that when there is an object having some electrical action between A and B, it enables the transfer of electrical signals between A and B.

[0020] In this specification, phrases indicating arrangements such as "above" and "below" are used for convenience to explain the positional relationship between components with reference to the drawings. Also, the positional relationship between components changes appropriately according to the direction in which each component is depicted. Therefore, it is not limited to the phrases described in the specification,

[0021] and can be appropriately rephrased according to the situation. The arrangement of each circuit block in the drawings is for specifying the positional relationship for explanation. Even if different circuit blocks are shown in the drawings to realize different functions, in an actual circuit or region, they may be provided so that different functions can be realized within the same circuit block. There are cases where the processing is provided to be performed by a plurality of circuit blocks.

[0022] Note that voltage indicates the potential difference between a certain potential and a reference potential (for example, ground potential). Often. Therefore, it is possible to rephrase voltage, potential, and potential difference as potential, voltage, and voltage difference, respectively. Note that voltage refers to the potential difference between two points, and potential refers to the electrostatic energy (electrical positional energy) possessed by a unit charge in an electrostatic field at a certain point. That's what it means.

[0023] Note that generally, potential and voltage are relative. Therefore, the ground potential is not necessarily limited to 0 volts.

[0024] Also, in this specification and the like, "parallel" means a state in which two straight lines are arranged at an angle of -10° or more and 10° or less. Therefore, cases of -5° or more and 5° or less are 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, cases of 85° or more and 95° or less are also included.

[0025] Also, in this specification and the like, when the crystal is trigonal or rhombohedral, it is represented as a hexagonal system. .

[0026] (Embodiment 1) In this embodiment, the configuration of the pixels included in a display device, which is one aspect of the present invention, will be described with reference to the drawings. Specifically.

[0027] FIG. 1(A) shows a display device 100 as an example of the display device. The display device 100 shown in FIG. 1(A) includes a pixel portion 11, a scanning line driving circuit 12, a signal line driving circuit 16, and each is parallel to or are arranged substantially in parallel and the scanning lines 17 whose potentials are controlled by the scanning line driving circuit 12 and signal lines 25 each of which is arranged in parallel or substantially in parallel and whose potentials are controlled by the signal line driving circuit 16 . Further, the pixel portion 11 has pixels 13 arranged in a matrix . Each pixel has a plurality of sub-pixels 14. Also, along the signal lines 25, there are capacitance lines 19 each of which is arranged in parallel or substantially in parallel and which supply the potential of the potential generation circuit 18 .

[0028] Note that the display device includes a driving circuit and the like for driving a plurality of pixels. Also, the display device may include a control circuit, a power supply circuit, a signal generation circuit, a backlight module, etc. arranged on another substrate and may be called a liquid crystal module. Note that the scanning line driving circuit 12 is a circuit having a function of driving the scanning lines 17 and may simply be referred to as a circuit. Also, the potential generation circuit 18 is a circuit having a function of generating the potential to be supplied to the capacitance lines 19 and may simply be referred to as a circuit. Also, the signal line driving circuit 16 is a circuit having a function of driving the signal lines 25 and may simply be referred to as a circuit. The pixel 13 has a function of controlling the transmission of light of four colors, which are RGB (red, green, blue) plus W (white), by the sub-pixels 14 and performing color display according to the additive color mixing of these lights. The sub-pixels that control the transmission of RGB lights have a colored film for making the light of the light source into light presenting each color. Note that the sub-pixel that controls the transmission of W light allows the light of the light source to pass through as it is if the light of the light source is white . Note that white may be not only the white obtained by the additive color mixing of RGB but also the white obtained by the color mixing of colors in a complementary color relationship

[0029] . . . . . .

[0030] The white obtained from the sub-pixels that transmit RGB light is the light that has passed through the color filter, so , it is the white obtained by being smaller than the intensity of the light emitted from the light source. As in one aspect of the present invention , the white obtained from the sub-pixels that transmit the W light that can transmit the light of the light source as it is is the white obtained with little reduction in the intensity of the light emitted from the light source. Therefore, the white obtained from the sub-pixels that transmit the RGBW light obtained in one aspect of the present invention is R It is white with a higher light intensity than the white obtained from the sub-pixels that transmit GB light. In other words , the white obtained from the sub-pixels that transmit RGBW light is white with reduced light intensity reduction . Therefore, in the configuration according to one aspect of the present invention using sub-pixels that transmit RGBW light , compared to the case of obtaining white with a display device having sub-pixels that transmit RGB light, the light of the light source can be weakened. As a result, the display device can reduce power consumption.

[0031] The sub-pixel 14 controls the conduction state of the transistor by applying a scanning signal, holds the data signal by a capacitive element, and drives the display element according to the amount of charge given by the data signal. In this way, it has a function of controlling light transmission. The sub-pixel 14 has first to fourth sub-pixels corresponding to each color of RGBW.

[0032] The scanning line 17 is, for example, electrically connected differently for each row among the sub-pixels 14 arranged in a matrix in the pixel portion 11. For example, the scanning line 17 in the first row is electrically connected to the sub-pixel 14 that controls the transmission of RGB light in the pixel 13 in the first row. Also, the scanning line 17 in the second row is the sub-pixel 14 that controls the transmission of W light in the pixel 13 in the first row, and is electrically connected to a sub-pixel 14 that controls the transmission of light of W in the pixel 13 in the second row The scanning line 17 in the third row is electrically connected to the sub-pixel 14 that controls the transmission of RGB light in the pixel 13 in the second row Note that the scanning line 17 is a wiring that gives a signal for selecting a sub-pixel and may be simply referred to as a wiring

[0033] The signal line 25 is, as an example, arranged in a matrix in the pixel portion 11, and the electrical connections are different for each column among the sub-pixels 14 For example, the signal line 25 in the first column is electrically connected to the sub-pixel 14 that controls the transmission of light of R in the pixel 13 in the first column The signal line 25 in the second column is electrically connected to the sub-pixel 14 that controls the transmission of light of G in the pixel 13 in the first column The signal line 25 in the third column is electrically connected to the sub-pixel 14 that controls the transmission of light of B in the pixel 13 electrically connected to the signal line in the first column, and the sub-pixel 14 that controls the transmission of light of W Note that the signal line 25 is a wiring that gives data to the sub-pixel by a data signal and may be simply referred to as a wiring

[0034] The capacitance line 19 is, as an example, the capacitance line 19 in the first column is electrically connected to the sub-pixel 14 that controls the transmission of RGBW light in the pixels 13 in the first to third columns Note that the capacitance line 19 is a wiring for giving a fixed potential to the sub-pixel and may be simply referred to as a wiring

[0035] Here, an example of a circuit configuration that can be used for the sub-pixel 14 of the display device shown in FIG. 1(A) is shown in FIGS. 27(A) and (B)

[0036] The sub-pixel 301 shown in FIG. 27(A) includes a liquid crystal element 31, a transistor 103, and a capacitive element ​​​​​​It has 105 and.

[0037] One of the potentials of a pair of electrodes of the liquid crystal element 31 is appropriately set according to the specifications of the sub-pixel 301. . The alignment state of the liquid crystal element 31 is set according to the data to be written. Also, a common potential (common potential ) may be applied to one of the pair of electrodes of the liquid crystal element 31 that each of the plurality of sub-pixels 301 has. Also, different potentials may be applied to one of the pair of electrodes of the liquid crystal element 31 for each sub-pixel 301 in each row.

[0038] Note that the liquid crystal element 31 is an element that controls the transmission or non-transmission of light by the optical modulation action of the liquid crystal. Note that the optical modulation action of the liquid crystal is controlled by an electric field applied to the liquid crystal (including a horizontal electric field, a vertical electric field, or an oblique electric field). Note that examples of the liquid crystal element 31 include nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, thermotropic liquid crystal, lyotropic liquid crystal, ferroelectric liquid crystal, antiferroelectric liquid crystal, etc.

[0039] As a driving method of the display device having the liquid crystal element 31, for example, TN mode, VA mode, ASM (Axially Symmetric Aligned Micro-cell ) mode, OCB (Optically Compensated Birefringence ) mode, MVA mode, PVA (Patterned Vertical Alignment) mode, IPS mode, FFS mode, or TBA (Transverse Bend Alignment) mode may be used. However, it is not limited to this, and various liquid crystal elements and their driving methods can be used.

[0040] Further, a liquid crystal device may be formed from 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 short response time of 1 msec or less. In addition, since the liquid crystal exhibiting a blue phase is optically isotropic, alignment treatment is not required, and the viewing angle dependence is small.

[0041] In the configuration of the sub-pixel 301 shown in FIG. 27(A), one of the source electrode and the drain electrode of the transistor 103 is electrically connected to the signal line 25, and the other is one of the pair of electrodes of the liquid crystal device 31. is electrically connected to the other. Further, the gate electrode of the transistor 103 is electrically connected to the scanning line 17. The transistor 103 has a function of controlling the writing of data of a data signal by being turned on or off.

[0042] In the configuration of the sub-pixel 301 shown in FIG. 27(A), one of the pair of electrodes of the capacitor element 105 is electrically connected to the capacitor line 19 to which a potential is supplied, and the other is one of the pair of electrodes of the liquid crystal device 31. is electrically connected to the other. Note that the value of the potential of the capacitor line 19 is appropriately set according to the specifications of the sub-pixel 301. The capacitor element 105 functions as a holding capacitor for holding the written data.

[0043] For example, in a display device having the sub-pixel 301 of FIG. 27(A), the scanning line driving circuit 12 sequentially selects the sub-pixels 301 of each row, turns on the transistor 103, and writes the data of the data signal.

[0044] The sub-pixel 301 in which data has been written enters a holding state when the transistor 103 is turned off. By sequentially performing this for each row, an image can be displayed.

[0045] Further, the sub-pixel 301 shown in FIG. 27(B) includes a transistor 43 that performs switching of the display element, a transistor 103 that controls the driving of the pixel, a transistor 45, and a capacitor element 1

[0046] 05 and a light-emitting element 41. One of the source electrode and the drain electrode of the transistor 43 is electrically connected to the signal line 25 to which a data signal is supplied.

[0047] The transistor 43 has a function of controlling the writing of data of the data

[0048] One of the source electrode and the drain electrode of the transistor 103 is electrically connected to the wiring 47 that functions as an anode line, and the other of the source electrode and the drain electrode of the transistor 103 is electrically connected to one electrode of the light-emitting element 41. Further, the gate electrode of the transistor 103 is electrically connected to

[0049] the other of the source electrode and the drain electrode of the transistor 43, and one electrode of the capacitor element 10 5.

[0050] One of the source electrode and the drain electrode of the transistor 45 is connected to the wiring 49 to which a reference potential of data is supplied, and the other of the source electrode and the drain electrode of the The gate electrode of transistor 45 is electrically connected to the scanning line 17 to which a gate signal is applied. It is connected.

[0051] Transistor 45 has a function of adjusting the current flowing through the light-emitting element 41. For example, when the internal resistance of the light-emitting element 41 increases due to deterioration or the like, the current flowing through the wiring 49 to which one of the source electrode and the drain electrode of the transistor 45 is connected is monitored, and thus the current flowing through the light-emitting element 41 can be corrected. The potential applied to the wiring 49 can be, for example, 0V. When the internal resistance of the light-emitting element 41 increases due to deterioration or the like of the light-emitting element 41 One of the source electrode and the drain electrode of the transistor 45 is connected to the wiring 49 to which the current flowing through the wiring 49 is monitored. The current flowing through the light-emitting element 41 can be corrected by monitoring the current flowing through the wiring 49. The potential applied to the wiring 49 can be, for example, 0V. As the potential applied to the wiring 49, for example, it can be 0V.

[0052] One of the pair of electrodes of the capacitor element 105 is electrically connected to the other of the source electrode and the drain electrode of the transistor 43, and the gate electrode of the transistor 103, and the other of the pair of electrodes of the capacitor element 105 is electrically connected to the other of the source electrode and the drain electrode of the transistor 45, and one of the electrodes of the light-emitting element 41. In the configuration of the sub-pixel 301 shown in FIG. 27(B), the capacitor element 105 has a function as a holding capacitor for holding the written data. One of the pair of electrodes of the capacitor element 105 is electrically connected to the other of the source electrode and the drain electrode of the transistor 45, and one of the electrodes of the light-emitting element 41. It is electrically connected.

[0053] In the configuration of the sub-pixel 301 shown in FIG. 27(B), the capacitor element 105 has a function as a holding capacitor for holding the written data. It has a function as a holding capacitor for holding the written data.

[0054] One of the pair of electrodes of the light-emitting element 41 is electrically connected to the other of the source electrode and the drain electrode of the transistor 45, the other of the pair of electrodes of the capacitor element 105, and the other of the source electrode and the drain electrode of the transistor 103. Also, the other of the pair of electrodes of the light-emitting element 41 is electrically connected to the wiring 50 that functions as a cathode line. One of the pair of electrodes of the light-emitting element 41 is electrically connected to the other of the source electrode and the drain electrode of the transistor 45, the other of the pair of electrodes of the capacitor element 105, and the other of the source electrode and the drain electrode of the transistor 103. As the light-emitting element 41, for example, an organic electroluminescence element (also referred to as an organic EL element) It is electrically connected to the wiring 50 that functions as a cathode line.

[0055] As the light-emitting element 41, for example, an organic electroluminescence element (also referred to as an organic EL element) ) etc. can be used. However, the light-emitting element 41 is not limited to this, and an inorganic EL element made of a material may be used.

[0056] Note that a high power supply potential VDD is applied to one of the wirings 47 and 50, and a low power supply potential VSS is applied to the other. In the configuration shown in FIG. 27(B), a high power supply potential VDD is applied to the wiring 47 and a low power supply potential VSS is applied to the wiring 50, respectively.

[0057] In the display device having the sub-pixel 301 of FIG. 27(B), the scanning line driving circuit 12 sequentially selects the sub-pixels 301 of each row, turns on the transistor 43, and writes the data of the data signal.

[0058] The sub-pixel 301 into which the data is written enters the holding state when the transistor 43 is turned off. Further, since the transistor 43 is connected to the capacitive element 105, the written data can be held for a long time. Also, the transistor 103 controls the amount of current flowing between the source electrode and the drain electrode, and the light-emitting element 41 emits light with a luminance corresponding to the amount of current flowing. By sequentially performing this for each row, an image can be displayed.

[0059] Note that in FIGS. 27(A) and 27(B), an example using the liquid crystal element 31 and the light-emitting element 41 as the display element is shown, but one aspect of the embodiment of the present invention is not limited to this. Various display elements can also be used. For example, an EL (electroluminescence) element (an EL element including organic and inorganic substances, an organic EL element, an inorganic EL element), an LED (a white LED, a red LED, a green LED, a blue LED, etc.), a transistor (a transistor that emits light according to current) Transistor), electron emission element, liquid crystal element, electronic ink, electrophoretic element, grating line Tobar valve (GLV), plasma display (PDP), MEMS (micro-electro Mechanical system) display element, digital micromirror device (DM D), DMS (digital microshutter), IMOD (interference Modulation) element, shutter-type MEMS display element, optical interference-type MEMS table Display element, electro-wetting element, piezoelectric ceramic display, carbon nanotube Tube, etc., there are those having a display medium in which contrast, brightness, reflectance, transmittance, etc. change due to electromagnetic action As an example of a display device using an EL element, there is an EL display Spray, etc. As an example of a display device using an electron emission element, there is a field emission Display (FED) or SED method flat panel display (SED: Surfa ce-conduction Electron-emitter Display) And so on. As an example of a display device using a liquid crystal element, there is a liquid crystal display (transmissive liquid crystal display Display, transflective liquid crystal display, reflective liquid crystal display, direct-view liquid crystal display Display, projection liquid crystal display), etc. As an example of a display device using electronic ink or an electrophoretic element There is electronic paper, etc. In addition, when realizing a transflective liquid crystal display or a reflective Type liquid crystal display, part or all of the pixel electrode may have the function as a reflective electrode For example, part or all of the pixel electrode may have aluminum Magnesium, silver, etc. Further, in that case, a memory circuit such as S RAM can be provided under the reflective electrode. Thereby, further power consumption can be reduced It can be done.

[0060] Next, Fig. 1(B) shows an example of the circuit configuration when the circuit configuration described in Fig. 27(A) is applied to the layout of Fig. 1(A). is shown.

[0061] In Fig. 1(B), as pixel 13, pixel 13_1 is shown as the pixel in the m-th row (m is a natural number), and pixel 13_2 is shown as the pixel in the (m + 1)-th row.

[0062] Pixel 13_1 has a sub-pixel 14R_1 that controls the transmission of R light, a sub-pixel 14G_1 that controls the transmission of G light, a sub-pixel 14B_1 that controls the transmission of B light, and a sub-pixel 14W_1 that controls the transmission of W light. Also, pixel 13_2 has a sub-pixel 14R_2 that controls the transmission of R light, a sub-pixel 14G_2 that controls the transmission of G light, a sub-pixel 14B_2 that controls the transmission of B light, and a sub-pixel 14W_2 that controls the transmission of W light.

[0063] Note that sub-pixels 14R_1 and 14R_2 may be referred to as the first sub-pixels. Note that sub-pixels 14G_1 and 14G_2 may be referred to as the second sub-pixels. Note that sub-pixels 14B_1 and 14B_2 may be referred to as the third sub-pixels. Note that sub-pixels 14W_1 and 14W_2 may be referred to as the fourth sub-pixels.

[0064] The sub-pixels 14R_1 to 14W_2 included in pixel 13_1 and pixel 13_2 each have a transistor 103, a capacitor element 105, and a liquid crystal element 31.

[0065] Also, in Fig. 1(B), as the scanning line 17, scanning line 17_1 is the scanning line in the M-th row (M is a natural number), scanning line 17_2 is the scanning line in the (M + 1)-th row, and scanning line is the scanning line in the (M + 2)-th row. The scanning line 17_3 is shown.

[0066] In addition, in FIG. 1(B), as the signal lines 25, the signal line 25_1 is used as the signal line of the n-th column (n is a natural number), the signal line 25_2 is used as the signal line of the (n + 1)-th column, and the signal line 25_3 is used as the signal line of the (n + 2)-th column. The signal line 25_1, the signal line 25_2, and the signal line 25_3 are shown. The signal line 25_3 is shown.

[0067] The sub-pixel 14R may be referred to as the first sub-pixel. The sub-pixel 14G may be referred to as the second sub-pixel. The sub-pixel 14B may be referred to as the third sub-pixel. The sub-pixel 14W may be referred to as the fourth sub-pixel. The sub-pixel 14R may be referred to as the first sub-pixel. The sub-pixel 14G may be referred to as the second sub-pixel. The sub-pixel 14B may be referred to as the third sub-pixel. The sub-pixel 14W may be referred to as the fourth sub-pixel. The sub-pixel 14W may be referred to as the fourth sub-pixel.

[0068] The first gate line, which is also a gate electrode, is connected to select three out of the four sub-pixels. The second gate line is connected to select the remaining sub-pixel and one sub-pixel in the next row. The second gate line is connected to select the remaining sub-pixel and one sub-pixel in the next row. The second gate line is connected to select the remaining sub-pixel and one sub-pixel in the next row.

[0069] By arranging the sub-pixels 14R_1 and 14R_2 in the pixels 13_1 and 13_2 as shown in FIGS. 1(A) and 1(B), the number of signal lines can be made the same as that of a pixel having stripe-arranged RGB sub-pixels. In addition, the number of scanning lines can be reduced to three for two pixels. By arranging the sub-pixels 14R_1 and 14R_2 in the pixels 13_1 and 13_2 as shown in FIGS. 1(A) and 1(B), the number of signal lines can be made the same as that of a pixel having stripe-arranged RGB sub-pixels. In addition, the number of scanning lines can be reduced to three for two pixels. By arranging the sub-pixels 14R_1 and 14R_2 in the pixels 13_1 and 13_2 as shown in FIGS. 1(A) and 1(B), the number of signal lines can be made the same as that of a pixel having stripe-arranged RGB sub-pixels. In addition, the number of scanning lines can be reduced to three for two pixels. By arranging the sub-pixels 14R_1 and 14R_2 in the pixels 13_1 and 13_2 as shown in FIGS. 1(A) and 1(B), the number of signal lines can be made the same as that of a pixel having stripe-arranged RGB sub-pixels. In addition, the number of scanning lines can be reduced to three for two pixels.

[0070] For example, when the display device is a liquid crystal display device and the four RGBW sub-pixels are arranged in a stripe pattern, although the number of data lines is four, the number of scanning lines is one, and the number of capacitance lines is one, and a total of six wirings can be used for control, the number of signal lines increases. For example, when the display device is a liquid crystal display device and the four RGBW sub-pixels are arranged in a stripe pattern, although the number of data lines is four, the number of scanning lines is one, and the number of capacitance lines is one, and a total of six wirings can be used for control, the number of signal lines increases. For example, when the display device is a liquid crystal display device and the four RGBW sub-pixels are arranged in a stripe pattern, although the number of data lines is four, the number of scanning lines is one, and the number of capacitance lines is one, and a total of six wirings can be used for control, the number of signal lines increases.

[0071] In addition, when the four RGBW sub-pixels are arranged in a 2×2 pattern, the number of data lines is two, the number of scanning lines Although it can be controlled using a total of five wirings, including two scanning lines and one capacitance line, the number of scanning lines increases for each row of pixels. In this case, the circuit configuration of the scanning line driving circuit 12 becomes large and it becomes difficult to narrow the bezel of the display device.

[0072] On the other hand, in the configuration disclosed in one aspect of the present invention, the sub-pixels 14R_1 to 14W_2 included in the pixels 13_1 and 13_2 arranged in two rows can be driven by three rows of scanning lines. In addition in the configuration disclosed in one aspect of the present invention, since the same number of signal lines as those in which three sub-pixels of RGB are arranged in stripes are sufficient, the number of signal lines can be reduced compared to the case where four sub-pixels of RGBW are arranged in stripes. Therefore, in particular, the circuit configuration of the scanning line driving circuit 12 can be made smaller and the bezel narrowing of the display device can be realized.

[0073] Next, FIG. 28(A) shows a cross-sectional view of the transistor 103 and the capacitive element 105 included in the display device. FIG.

[0074] The transistor 103 shown in FIG. 28(A) includes a conductive film 304c that functions as a gate electrode provided on a substrate 302, a gate insulating film 51 formed on the substrate 302 and the conductive film 304c, an oxide semiconductor film 308b that overlaps the conductive film 304c via the gate insulating film 51, and a pair of conductive films 310d and 310e that are in contact with the oxide semiconductor film 308b and function as a source electrode and a drain electrode. has

[0075] In addition, a metal oxide film 308c is provided on the gate insulating film 51. Note that the metal oxide film 308c is in contact with one of the pair of conductive films, i.e., the conductive film 310e, included in the transistor 103. Next, an inorganic insulating film 53 is provided on the transistor 103 and the metal oxide film 308c. A conductive film 316b is provided on the inorganic insulating film 53. The metal oxide film 308c, the inorganic insulating film 53, and the conductive film 316b constitute a capacitor element 105.

[0076] An organic insulating film 317 is provided on the inorganic insulating film 53 and the conductive film 316b. Also, at the openings provided in the inorganic insulating film 53 and the organic insulating film 317, a conductive film 319 that connects to the conductive film 310e is provided on the organic insulating film 317. The conductive film 319 functions as a pixel electrode.

[0077] The metal oxide film 308c is an oxide semiconductor film formed simultaneously with the oxide semiconductor film 308b, to which impurities such as hydrogen, boron, phosphorus, nitrogen, tin, antimony, noble gas elements, alkali metals, and alkaline earth metals are added, and oxygen deficiency is caused, thereby improving conductivity and becoming a film having conductivity. Since the oxide semiconductor film has translucency, the metal oxide film 308c also has translucency.

[0078] In the oxide semiconductor in which oxygen deficiency is formed, when hydrogen enters the oxygen deficiency site, a donor level is formed near the conduction band. As a result, the oxide semiconductor becomes highly conductive and becomes a conductor. The oxide semiconductor that has become a conductor is called a metal oxide film, and is also sometimes called an oxide conductor. Generally, since the oxide semiconductor has a large energy gap, it has translucency to visible light. On the other hand, the oxide conductor is an oxide semiconductor having a donor level near the conduction band. Therefore, the influence of absorption by the donor level is small, and it has translucency comparable to that of the oxide semiconductor with respect to visible light.

[0079] The conductive film 316b and the conductive film 319 are formed using a light-transmitting conductive film. Therefore, the area of ​​the capacitor in the pixel is large. It is possible to increase the capacitance of the capacitive element and the aperture ratio of the pixel.

[0080] The inorganic insulating film 53 includes at least an oxide insulating film, and further includes an oxide insulating film and a nitride insulating film. In the inorganic insulating film 53, the oxide semiconductor film 308 is preferably laminated. In the region in contact with the oxide semiconductor film 308b, an oxide insulating film is formed. The amount of defects at the interface with the inorganic insulating film 53 can be reduced.

[0081] The nitride insulating film functions as a barrier film against water, hydrogen, and the like. When water, hydrogen, or the like is contained in the oxide semiconductor film 308b, the water, hydrogen, or the like is mixed with oxygen contained in the oxide semiconductor film 308b. The reaction occurs, and oxygen vacancies are formed. carriers are generated, the threshold voltage of the transistor is shifted negatively, and the normally-on Therefore, by providing a nitride insulating film on the inorganic insulating film 53, The amount of diffusion of water, hydrogen, and the like from the oxide semiconductor film 308b to the oxide semiconductor film 308b can be reduced. Therefore, the amount of defects in the inorganic insulating film 53 can be reduced. In this case, an oxide insulating film and a nitride insulating film are stacked in this order from the oxide semiconductor film 308b side. As a result, the number of defects at the interface between the oxide semiconductor film 308b and the inorganic insulating film 53 and the amount of oxygen It is possible to reduce the amount of oxygen vacancies in the oxide semiconductor film 308b. It is possible to fabricate transistors with the following characteristics.

[0082] The organic insulating film 317 is formed of an organic resin such as an acrylic resin, a polyimide resin, or an epoxy resin, so it has high flatness. Also, the thickness of the organic insulating film 317 is 500 nm or more and 5000 nm or less, preferably 1000 nm or more and 3000 nm or less.

[0083] In addition, the conductive film 319 formed on the organic insulating film 317 is connected to the transistor 103. The conductive film 319 functions as a pixel electrode and is connected to the transistor 103 through an opening provided in the inorganic insulating film 53 and the organic insulating film 317. That is, since the conductive film 319 is at a distance from the transistor 103, it is less likely to be affected by the potential of the conductive film 310d of the transistor 103. As a result, the conductive film 319 can be overlapped with the transistor 103, and the aperture ratio of the pixel can be increased.

[0084] Here, as a comparative example, in a display device having a transistor 103 on which the organic insulating film 317 is not formed on the inorganic insulating film 53, the case where a negative voltage is applied to the conductive film 304c that functions as the gate electrode of the transistor 103 will be described. When a negative voltage is applied to the conductive film 304c that functions as the gate electrode of the transistor 103, an electric field is generated. This electric field is not shielded by the oxide semiconductor film 308b and affects the inorganic insulating film 53,

[0085] so that a weak positive charge is charged on the surface of the inorganic insulating film 53. Also, when a negative voltage is applied to the conductive film 304c that functions as the gate electrode, positive charged particles contained in the air are adsorbed on the surface of the inorganic insulating film 53, and a weak positive charge is charged on the surface of the inorganic insulating film 53.

[0086] ​​​​​​When a positive charge accumulates on the surface of the inorganic insulating film 53, an electric field is generated, which affects the interface between the oxide semiconductor film 308b and the inorganic insulating film 53. As a result, a substantially positive bias is applied to the interface between the oxide semiconductor film 308b and the inorganic insulating film 53, causing the threshold voltage of the transistor to shift negatively. On the other hand, the transistor 103 shown in Fig. 28(A) has an organic insulating film 317 on the inorganic insulating film 53. Since the organic insulating film 317 is thick, the electric field generated by applying a negative voltage to the conductive film 304c that functions as a gate electrode does not affect the surface of the organic insulating film 317, making it difficult for a positive charge to accumulate on the surface of the organic insulating film 317. Even if positive charged particles contained in the air are adsorbed on the surface of the organic insulating film 317, the electric field of the positive charged particles adsorbed on the surface of the organic insulating film 317 hardly affects the interface between the oxide semiconductor film 308b and the inorganic insulating film 53 because the organic insulating film 317 is thick.

[0087] As a result, a substantially positive bias is not applied to the interface between the oxide semiconductor film 308b and the inorganic insulating film 53, and the variation in the threshold voltage of the transistor is small. In addition, although water and the like easily diffuse in the organic insulating film 317, since the inorganic insulating film 53 has a nitride insulating film, the nitride insulating film serves as a water barrier, preventing the water diffused into the organic insulating film 317 from diffusing into the oxide semiconductor film 308b. From the above, by providing the organic insulating film 317 on the transistor, it is possible to reduce the variation in the electrical characteristics of the transistor. In addition, it has a normally-off characteristic and is reliable. Moreover, in the organic insulating film 317, water and the like easily diffuse, but since the inorganic insulating film 53 has a nitride insulating film, the nitride insulating film serves as a water barrier, preventing the water diffused into the organic insulating film 317 from diffusing into the oxide semiconductor film 308b. As a result, a substantially positive bias is not applied to the interface between the oxide semiconductor film 308b and the inorganic insulating film 53, and the variation in the threshold voltage of the transistor is small. Furthermore, in the organic insulating film 317, water and the like easily diffuse, but since the inorganic insulating film 53 has a nitride insulating film, the nitride insulating film serves as a water barrier, preventing the water diffused into the organic insulating film 317 from diffusing into the oxide semiconductor film 308b. As a result, a substantially positive bias is not applied to the interface between the oxide semiconductor film 308b and the inorganic insulating film 53, and the variation in the threshold voltage of the transistor is small. In addition, in the organic insulating film 317, water and the like easily diffuse, but since the inorganic insulating film 53 has a nitride insulating film, the nitride insulating film serves as a water barrier, preventing the water diffused into the organic insulating film 317 from diffusing into the oxide semiconductor film 308b.

[0088] Moreover, although water and the like easily diffuse in the organic insulating film 317, since the inorganic insulating film 53 has a nitride insulating film, the nitride insulating film serves as a water barrier, preventing the water diffused into the organic insulating film 317 from diffusing into the oxide semiconductor film 308b. From the above, by providing the organic insulating film 317 on the transistor, it is possible to reduce the variation in the electrical characteristics of the transistor. In addition, it has a normally-off characteristic and is reliable.

[0089] From the above, by providing the organic insulating film 317 on the transistor, it is possible to reduce the variation in the electrical characteristics of the transistor. In addition, it has a normally-off characteristic and is reliable. A highly efficient transistor can be fabricated. Also, since the organic insulating film can be formed using a printing method, a coating method, etc., the fabrication time can be shortened. Also, By providing a conductive film that functions as a pixel electrode on the organic insulating film 317, the aperture ratio in the pixel can be increased. By providing a conductive film that functions as a pixel electrode on the organic insulating film 317, the aperture ratio in the pixel can be increased. By providing a conductive film that functions as a pixel electrode on the organic insulating film 317, the aperture ratio in the pixel can be increased.

[0090] <Regarding the oxide conductor (metal oxide film)> Here, the temperature dependence of the resistivity in each of the film formed of an oxide semiconductor (hereinafter referred to as an oxide semiconductor film (OS)) and the film formed of an oxide conductor (hereinafter referred to as an oxide conductor film (OC)) will be described with reference to FIG. 29. In FIG. 29, the horizontal axis represents the measurement temperature, and the vertical axis represents the resistivity. Also, the measurement results of the oxide semiconductor film (OS) are indicated by circles, Here, the temperature dependence of the resistivity in each of the film formed of an oxide semiconductor (hereinafter referred to as an oxide semiconductor film (OS)) and the film formed of an oxide conductor (hereinafter referred to as an oxide conductor film (OC)) will be described with reference to FIG. 29. In FIG. 29, the horizontal axis represents the measurement temperature, and the vertical axis represents the resistivity. Also, the measurement results of the oxide semiconductor film (OS) are indicated by circles, and the measurement results of the oxide conductor film (OC) are indicated by squares.

[0091] Note that the sample containing the oxide semiconductor film (OS) was formed by sputtering a 35-nm-thick In-Ga-Zn oxide film on a glass substrate using a sputtering target with an atomic ratio of In:Ga: Zn = 1:1:1.2, and a 20-nm-thick In-Ga-Zn oxide film was formed by sputtering using a sputtering target with an atomic ratio of In:Ga:Zn = 1:4: 5, heat-treated in a nitrogen atmosphere at 450°C, then heat-treated in a mixed gas atmosphere of nitrogen and oxygen at 450°C, and further an oxynitride silicon film was formed by plasma CVD method 5, heat-treated in a nitrogen atmosphere at 450°C, then heat-treated in a mixed gas atmosphere of nitrogen and oxygen at 450°C, and further an oxynitride silicon film was formed by plasma CVD method to produce it. to produce it. to produce it.

[0092] Also, the sample containing the oxide conductor film (OC) was formed by sputtering a 10-nm-thick film on a glass substrate using a sputtering target with an atomic ratio of In:Ga: Zn = 1:1:1 by sputtering, An In-Ga-Zn oxide film of 0 nm was formed and heat-treated in a nitrogen atmosphere at 450 °C, and then heat-treated in a mixed gas atmosphere of nitrogen and oxygen at 450 °C, and a silicon nitride film was formed by plasma CVD method to fabricate it.

[0093] As can be seen from Fig. 29, the temperature dependence of the resistivity in the oxide conductor film (OC) is smaller than that in the oxide semiconductor film (OS). Typically, the change rate of the resistivity of the oxide conductor film (OC) at 80 K or higher and 2 90 K or lower is less than ±20%. Or, the change rate of the resistivity at 150 K or higher and 250 K or lower is less than ±10%. That is, the oxide conductor is a degenerate semiconductor, and it is estimated that the conduction band edge and the Fermi level coincide or are substantially coincident. Therefore, the oxide conductor film can be used for wiring, electrodes, pixel electrodes, etc. <Modification Example 1>

[0094] A modification example of the transistor shown in Fig. 28(A) will be described with reference to Fig. 28(B). In this modification example, the transistor 103c is characterized by having an oxide semiconductor film 308e formed using a multi-tone mask and a pair of conductive films 310f, 310g. Further, the transistor 103c and the capacitor element 105 are connected by a conductive film 319 that functions as a pixel electrode and are characterized by this.

[0095] By using a multi-tone mask, it is possible to form a resist mask having a plurality of thicknesses. After forming the oxide semiconductor film 308e using the resist mask, the resist mask is exposed to oxygen plasma or the like, and a part of the resist mask is removed to form a pair of conductive films. ​​It becomes a resist mask for forming. Therefore, the number of photolithography processes in the manufacturing process of the oxide semiconductor film 308e and the pair of conductive films 310f and 310g can be reduced. possible.

[0096] Note that a part of the oxide semiconductor film 308e formed using the multi-tone mask extends beyond the pair of conductive films 310f and 310g in the planar shape and is not covered by the pair of conductive films 310f and 310g. That is, a part of the oxide semiconductor film 308e is exposed outside the pair of conductive films 310f and 310g. 0g.

[0097] Also, in FIG. 28(B), the metal oxide film 308f is formed on the gate insulating film 51. Also, on the metal oxide film 308f, the conductive film 310h is formed simultaneously with the conductive films 310f and 310g. Also, the conductive film 319 is connected to the conductive film 310g and the conductive film 310h. As a result, the transistor 103c and the capacitor element 105 are electrically connected.

[0098] <Modification 2> A modification of the transistor shown in FIG. 28(A) will be described with reference to FIG. 28(C). The transistor 103d shown in this modification is characterized in that it is a transistor formed with a channel protection structure.

[0099] The transistor 103d with the channel protection structure has an opening in the insulating film 53a, and the oxide semiconductor film 308b and the pair of conductive films 310i and 310j are connected at the opening. By adopting this shape, damage to the oxide semiconductor film 308b can be reduced.

[0100] <Modification 3> ​​​​​​​​​​In the display device shown in FIGS. 28(A) to (C), in some cases or depending on the situation, for example, as the conductive film 319, a conductive film having a function of reflecting light may be used for formation. Alternatively, as the conductive film 319, a laminated film may be used for formation, and as at least one film of the laminated film, a conductive film having a function of reflecting light may be used. As an example of the material of the conductive film having a function of reflecting light, silver, aluminum, chromium, copper, tantalum, titanium, molybdenum, tungsten, etc. can be used. Or, as the conductive film 319, a laminated film formed using silver and sandwiched between ITO above and below may be used for formation. In such a case, the display device shown in FIGS. 28(A) to (C) can be applied to a reflective display device, a transflective display device, a light-emitting device with a top emission structure, etc.

[0101] In the display device according to one aspect of the present invention described above, in a configuration having a first pixel having first to fourth sub-pixels and a second pixel having first to fourth sub-pixels provided in the next row of the first pixel, a first wiring for supplying a signal for selecting the first to third sub-pixels included in the first pixel, and a second wiring for selecting the fourth sub-pixel included in the first pixel are provided, and the second wiring is a wiring for selecting the fourth sub-pixel included in the second pixel.

[0102] Therefore, the number of signal lines can be made the same as the number of signal lines in which three sub-pixels of RGB are arranged in stripes, and the number of scanning lines per two rows of pixels can be reduced to three, so that the circuit configuration of the scanning line driving circuit 12 can be made smaller. And the narrow bezel of the display device can be realized.

[0103] In addition, in the display device according to one embodiment of the present invention, the capacitor has a light-transmitting property. Therefore, it is possible to form a large capacitance element (large area). Generally speaking, it is possible to set the capacity at 50% or more, preferably 60% or more, and at the same time, to increase the capacity value. For example, a display device with high resolution, such as a liquid crystal display, can be obtained. In the device, the area of ​​the pixel is reduced, and the area of ​​the capacitance element is also reduced. In a display device with a high image quality, the amount of charge stored in the capacitance element is small. Since the capacitor 105 shown in this embodiment has a light-transmitting property, the capacitor is provided in a pixel. This makes it possible to increase the aperture ratio while obtaining a sufficient capacitance value in each pixel.

[0104] In addition, in a liquid crystal display device, the larger the capacitance of the capacitance element, the greater the capacitance of the capacitance element. By using the liquid crystal display, the period during which the alignment of the liquid crystal molecules in the liquid crystal element can be kept constant can be extended. When displaying a still image, the period can be extended, reducing the number of times the image data is rewritten. It is possible to reduce the power consumption. This structure allows the aperture ratio to be increased even in high-resolution display devices, It is possible to efficiently use light from light sources such as ceiling lamps, thereby reducing the power consumption of display devices. It is possible.

[0105] The pixels are divided into four types: R subpixels, G subpixels, B subpixels, and W subpixels. However, one embodiment of the present invention is not limited to this. It is sufficient that the pixel has at least a plurality of sub-pixels among the four types of sub-pixels. The sub-pixels included in each pixel may be different depending on the pixel.

[0106] For example, the first pixel may have an R sub-pixel, a G sub-pixel, and a B sub-pixel, and the second pixel may have an R sub-pixel, a G sub-pixel, and a W sub-pixel. Alternatively, the first pixel may have an R sub-pixel , a G sub-pixel, and the second pixel may have a B sub-pixel and a W sub-pixel. Alternatively, the first pixel may have an R sub-pixel, a G sub-pixel, and a B sub-pixel, and the second pixel may have an R sub-pixel , a G sub-pixel, a B sub-pixel, and a W sub-pixel.

[0107] Note that the configurations and methods shown in this embodiment can be appropriately combined and used with the configurations and methods shown in other embodiments.

[0108] (Embodiment 2) In this embodiment, a display device and a method for manufacturing the same, which are aspects of the present invention, will be described with reference to drawings showing specific configurations.

[0109] First, the specific configuration of the element substrate included in the display device will be described. Here, a VA-mode liquid crystal display device is used as the display device, and the sub-pixels 14R_1, 1 4G_1, 14B_1, 14W_1, 14R_2, 14G_2, 14B_2, 14W_2 (hereinafter referred to as sub-pixel 14) will be described with reference to a top view. In FIG. 2, a top view showing the arrangement of the members on the element substrate side in the sub-pixel 14 is shown. Further, in FIG. 3, a top view showing the arrangement of the members on the counter substrate side corresponding to the top view of the members on the element substrate side shown in FIG. 2 is shown. Note that FIGS. 2 and 3 are top views corresponding to the circuit configuration shown in FIG. 1(B).

[0110] ​​​In FIG. 2, the conductors functioning as scanning lines for the sub-pixels 14R_1, 14G_1, and 14B_1 are The conductive film 304c and the conductive film 304d functioning as the scanning lines of 14W_1 and 14W_2 are The conductive film functions as a signal line, and extends in a direction substantially perpendicular to the conductive film (left and right direction in the drawing). The conductive film 310d functioning as a signal line is substantially perpendicular to the conductive film functioning as a scanning line. The conductive film that functions as the scanning line is provided so as to extend in the direction in which the scanning line is formed (the vertical direction in the drawing). 304c is electrically connected to the scanning line driving circuit 12 (see FIG. 1(A)) and The conductive film 310d functioning as a signal line is connected to the signal line driver circuit 16 (see FIG. 1A). are electrically connected.

[0111] The transistor 103 has a conductive film functioning as a scan line and a conductive film functioning as a signal line. The transistor 103 is provided in the intersecting region. A film 304c, a gate insulating film (not shown in FIG. 2), and a channel formed on the gate insulating film. The oxide semiconductor film 308b in which the regions are formed functions as a source electrode and a drain electrode. The conductive film 304c is a pair of conductive films 310d and 310e. The region overlapping with the oxide semiconductor film 308b also functions as a conductive film. The conductive film 310d functions as a gate electrode of the gate electrode 103. The oxide semiconductor film 308b also functions as a conductive film for the transistor 103. In FIG. 2, the gate electrode functions as a scanning line. The conductive film has an end portion located outside an end portion of the oxide semiconductor film 308b in a top view. For this reason, the conductive film that functions as the scanning line blocks light from a light source such as a backlight. It functions as a light-shielding film. 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 can be suppressed.

[0112] Further, the metal oxide film 308c is connected to the conductive film 310e included in the transistor 103. Also, on the metal oxide film 308c, a conductive film 316b is provided via an insulating film. In the insulating film provided on the metal oxide film 308c, an opening 362 is provided. In the opening 362, the metal oxide film 308c is in contact with a nitride insulating film (not shown in FIG. 2).

[0113] The capacitor element 105 is formed in a region where the metal oxide film 308c and the conductive film 316b overlap. The metal oxide film 308c and the conductive film 316b have translucency. That is, the capacitor element 105 has translucency.

[0114] The conductive film 319 that functions as a pixel electrode is provided on the conductive film 310e and the conductive film 316b via an organic insulating film (not shown in FIG. 2). Also, the conductive film 319 is connected to the conductive film 310e at the opening 364c. That is, the transistor 103, the capacitor element 105, and the conductive film 319 are electrically connected.

[0115] Since the capacitor element 105 has translucency, the capacitor element 105 can be formed large (in a large area) in the sub-pixel 14. Therefore, while increasing the aperture ratio, typically 50% or more, preferably 60% or more, it is possible to obtain a display device with an increased capacitance value. For example, in a display device with high resolution, such as a liquid crystal display device, the area of the pixel The product becomes smaller, and the area of the capacitive element also becomes smaller. Therefore, in a display device with high resolution, the amount of charge stored in the capacitive element becomes smaller. However, since the capacitive element 105 shown in this embodiment has translucency, by providing the capacitive element in a pixel, it is possible to increase the aperture ratio while obtaining a sufficient capacitance value. Typically, it can be suitably used for a high-resolution display device with a pixel density of 200 ppi or more, further 300 ppi or more, and even more 500 ppi or more.

[0116] In addition, in a liquid crystal display device, the larger the capacitance value of the capacitive element, the longer the period during which the alignment of the liquid crystal molecules in the liquid crystal element can be kept constant in the presence of an electric field. When displaying a still image, since this period can be lengthened, it is possible to reduce the number of times of rewriting image data and reduce the power consumption. Also, due to the structure shown in this embodiment, even in a high-resolution display device, the aperture ratio can be increased, so the light of a light source such as a backlight can be efficiently utilized, and the power consumption of the display device

[0117] can be reduced. Also, in the top view of the counter substrate side corresponding to the top view of FIG. 2 shown in FIG. 3, an arrangement example of the sub-pixel 14 is shown. In the sub-pixel 14, in the opening provided in the light-shielding portion BM, the colored films R1,

[0118] G1, B1, the layer W1 having translucency, the colored films R2, G2, B2, and the layer W2 having translucency are provided.

[0119] The colored films R1, G1, B1, R2, G2, and B2 are layers for making the light of the light source passing through them into light presenting a predetermined color. Typically, a color filter can be used and arranged in the corresponding sub-pixels of the RGB sub-pixels. That is, it may be arranged in the sub-pixels.

[0120] The light-transmissive layers W1 and W2 are layers for transmitting the light of the light source. Typically, an organic resin such as acrylic resin, polyimide, or epoxy resin can be used and arranged in the sub-pixels corresponding to the W sub-pixels. It should be noted that the light-transmissive layers W1 and W2 may not be arranged. Alternatively, as a layer having the light-transmissive layers W1 and W2, a layer that absorbs light of a specific wavelength may be provided. In this case, for example, even if an appropriate white cannot be obtained depending on the wavelength of the light of the light source, the white balance can be adjusted, so that a display with high color purity can be performed. Next, a cross-sectional view between the lines C-D in FIGS. 2 and 3 is shown in FIG. 4. In FIG. 4, a cross-sectional view of the drive circuit portion (the upper view is omitted) including the scanning line drive circuit 12 and the signal line drive circuit 16 described in FIG. 1 is shown at A-B. In the present embodiment, a VA-mode liquid crystal display device will be described as the display device. The liquid crystal display device shown in the present embodiment has liquid crystal elements 322 sandwiched between a pair of substrates (substrate 302 and substrate 342). The liquid crystal element 322 has a conductive film 319 above the substrate 302, films for controlling the orientation (hereinafter referred to as alignment films 320 and 352), a liquid crystal layer 321, and a conductive film 350. The conductive film 319 functions as one electrode of the liquid crystal element 322, and the conductive film 350 functions as the other electrode of the liquid crystal element 3. That is, it functions as the other electrode of the liquid crystal element 322.

[0121] Next, a cross-sectional view between the lines C-D in FIGS. 2 and 3 is shown in FIG. 4. Note that in FIG. 4, a cross-sectional view of the drive circuit portion (the upper view is omitted) including the scanning line drive circuit 12 and the signal line drive circuit 16 described in FIG. 1 is shown at A-B. In the present embodiment, a VA-mode liquid crystal display device will be described as the display device. The liquid crystal display device shown in the present embodiment has liquid crystal elements 322 sandwiched between a pair of substrates (substrate 302 and substrate 342). In the present embodiment, a VA-mode liquid crystal display device will be described as the display device. That is, a VA-mode liquid crystal display device will be described as the display device.

[0122] The liquid crystal display device shown in the present embodiment has liquid crystal elements 322 sandwiched between a pair of substrates (substrate 302 and substrate 342). That is, the liquid crystal elements 322 are sandwiched between a pair of substrates (substrate 302 and substrate 342).

[0123] The liquid crystal element 322 has a conductive film 319 above the substrate 302, films for controlling the orientation (hereinafter referred to as alignment films 320 and 352), a liquid crystal layer 321, and a conductive film 350. Note that the conductive film 319 functions as one electrode of the liquid crystal element 322, and the conductive film 350 functions as the other electrode of the liquid crystal element 3. That is, the conductive film 319 functions as one electrode of the liquid crystal element 322, and the conductive film 350 functions as the other electrode of the liquid crystal element 322. functions as the other electrode of 22.

[0124] Thus, a liquid crystal display device refers to a device having liquid crystal elements. Note that the liquid crystal display device includes a drive circuit for driving a plurality of pixels and the like. Further, the 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 referred to as a liquid crystal module.

[0125] In the drive circuit section, a transistor 102 is constituted by a conductive film 304a functioning as a gate electrode, insulating films 305 and 306 functioning as a gate insulating film 51, an oxide semiconductor film 308a in which a channel region is formed, and conductive films 310a and 310b functioning as source and drain electrodes. The oxide semiconductor film 308a is provided on the gate insulating film 51.

[0126] In the pixel section, a transistor 103 is constituted by a conductive film 304c functioning as a gate electrode, insulating films 305 and 306 functioning as a gate insulating film 51, an oxide semiconductor film 308b in which a channel region formed on the gate insulating film 51 is formed, and conductive films 310d and 310e functioning as source and drain electrodes. The oxide semiconductor film 308b is provided on the gate insulating film 51. Further, insulating films 312 and 314, which are the insulating film 53, are provided as protective films on the conductive films 310d and 310e.

[0127] Further, a capacitor element 105 is constituted by a metal oxide film 308c functioning as one electrode, an insulating film 314 functioning as a dielectric film, and a conductive film 316b functioning as the other electrode. ​​​​​​​​​​​​The oxide film 308c is provided on the gate insulating film 51.

[0128] An organic insulating film 317 is formed on the inorganic insulating film 53. Also, on the organic insulating film 317, a conductive film 319 that functions as a pixel electrode is formed. The conductive film 319 is connected to the conductive film 310e.

[0129] Also, in the drive circuit section, the conductive film 304b formed simultaneously with the conductive films 304a and 304c, and the conductive film 310c formed simultaneously with the conductive films 310a, 310b, 310d, and 310e are connected by a conductive film 319a formed simultaneously with the conductive film 319.

[0130] The conductive film 304b and the conductive film 319a are connected at openings provided in the insulating films 305, 306, 312, 314, and the organic insulating film 317. Also, the conductive film 310c and the conductive film 319a are connected at openings provided in the insulating films 312, 314, and the organic insulating film 317.

[0131] Although not shown, the conductive film 316b is electrically connected to a conductive film formed simultaneously with the conductive films 319 and 319a, or a conductive film formed simultaneously with the conductive films 304a, 304b, and 304c, or a conductive film formed simultaneously with the conductive films 310a, 310b, 310c, 310d, and 310e. Also, an arbitrary potential such as a common potential or a ground potential is applied to the conductive film 316b via a conductive film formed simultaneously with the conductive films 304a, 304b, and 304c, or a conductive film formed simultaneously with the conductive films 310a, 310b, 310c, 310d, and 310e.

[0132] Here, the components of the display device shown in FIG. 4 will be described below. ​​​​​​​​​​​

[0133] Conductive films 304a, 304b, and 304c are formed on the substrate 302. The conductive film 4a functions as a gate electrode of a transistor in the driving circuit section. 04b is formed in the driving circuit section and is connected to the conductive film 310c. , which is formed in the pixel section 11 and functions as a gate electrode of a transistor in the pixel section.

[0134] There is no particular restriction on the material of the substrate 302, but it should be at least strong enough to withstand the subsequent heat treatment. It is necessary to have heat resistance. For example, glass substrate, ceramic substrate, quartz substrate, surface treatment substrate, etc. A fiber substrate or the like may be used as the substrate 302. Also, silicon or silicon carbide may be used as the material. Single crystal semiconductor substrates, polycrystalline semiconductor substrates, and compound semiconductor substrates such as silicon germanium It is also possible to use a substrate, an SOI substrate, or the like, on which a semiconductor element is provided. The substrate 302 may be a glass substrate. In this case, 6th generation (1500mm x 1850mm), 7th generation (1870mm x 2200 mm), 8th generation (2200mm x 2400mm), 9th generation (2400mm x 2800 By using large area substrates such as 10th generation (2950mm x 3400mm), It is possible to manufacture a liquid crystal display device of this type.

[0135] In addition, a flexible substrate is used as the substrate 302, and a transistor is formed directly on the flexible substrate. Alternatively, a peeling layer may be provided between the substrate 302 and the transistor. After completing a part or the whole of the element part on it, it is separated from the substrate 302 and attached to another substrate. In this case, the transistors are mounted on substrates with poor heat resistance or flexible substrates. It can also be transferred onto a substrate.

[0136] As the conductive films 304a, 304b, and 304c, a metal element selected from aluminum, chromium, copper, tantalum, titanium, molybdenum, tungsten, an alloy containing the above-described metal element, or an alloy formed by combining the above-described metal elements can be used to form them. Also, a metal element selected from any one or more of manganese and zirconium may be used. Further, the conductive films 304a, 304b, and 304c may have a single-layer structure or a multilayer structure of two or more layers. For example, a single-layer structure of an aluminum film containing silicon, 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 and an aluminum film are laminated on the titanium film and then a titanium film is formed thereon, etc. are available. In addition, an alloy film or a nitride film formed by combining one or more selected from titanium, tantalum, tungsten, molybdenum, chromium, neodymium, and scandium with aluminum may be used.

[0137] Further, the conductive films 304a, 304b, and 304c may be applied with a conductive material having translucency such as indium tin oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, indium tin oxide added with silicon oxide, etc. Also, a laminated structure of the above-described conductive material having translucency and the above-described metal element can be used. ​

[0138] On the substrate 302 and the conductive films 304a, 304c, and 304b, an insulating film 305 and an insulating film 3 06 are formed. The insulating film 305 and the insulating film 306 function as the gate insulating film 51 of the transistor in the drive circuit section and the gate insulating film 51 of the transistor in the pixel section 11.

[0139] As the insulating film 305, for example, a nitride insulating film such as silicon nitride, silicon oxynitride, aluminum nitride, or aluminum oxynitride is preferably used for formation.

[0140] As the insulating film 306, for example, silicon oxide, silicon oxynitride, silicon nitride oxynitride, silicon nitride, aluminum oxide, hafnium oxide, gallium oxide, or a Ga-Zn-based metal oxide, etc. may be used, and it may be provided in a laminated or single-layer form. Further, as the insulating film 306, hafnium silicate (HfSiO x )、hafnium silicate with nitrogen added (HfS i x O y N z )、hafnium aluminate with nitrogen added (HfAl x O y N z )、acid By using high-k materials such as hafnium oxide and yttrium oxide, the gate leakage of the transistor can be reduced.

[0141] The total thickness of the insulating film 305 and the insulating film 306 is 5 nm or more and 400 nm or less, more preferably 10 nm or more and 300 nm or less, and even more preferably 50 nm or more and 250 nm or less.

[0142] An oxide semiconductor film 308a, 308b, and a metal oxide film 308c are formed on the insulating film 306. The oxide semiconductor film 308a is formed at a position overlapping with the conductive film 304a and functions as a channel region of a transistor in the driving circuit section. Also, the oxide semiconductor film 308b is formed at a position overlapping with the conductive film 304c and functions as a channel region of a transistor in the pixel section. The metal oxide film 308c is connected to the conductive film 310e included in the transistor 103 and functions as an electrode of the capacitor element 105.

[0143] Typically, the oxide semiconductor films 308a, 308b, and the metal oxide film 308c are In-Ga oxide, In-Zn oxide, In-M-Zn oxide (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf). In addition, the oxide semiconductor films 308a, 308b, and the metal oxide film 308c have translucency. When the oxide semiconductor films 308a, 308b, and the metal oxide film 308c are In-M-Zn oxide, the atomic number ratio of In and M is such that In is 25 atomic% or more and M is less than 75 atomic% when the sum of In and M is 100 atomic%, and more preferably In is 34 atomic% or more and M is less than 66 atomic%.

[0144]

[0145] The oxide semiconductor films 308a, 308b, and the metal oxide film 308c have an energy gap of 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. In this way, by using an oxide semiconductor with a wide energy gap, the off-current of the transistor can be reduced.

[0146] The thicknesses of the oxide semiconductor films 308a and 308b and the metal oxide film 308c are 3 nm or more and 2 00 nm or less, preferably 3 nm or more and 100 nm or less, more preferably 3 nm or more and 50 nm or less.

[0147] As the oxide semiconductor films 308a and 308b and the metal oxide film 308c, In:Ga:Zn = 1:1:1, In:Ga:Zn = 1:1:1.2, or In having an atomic ratio of 3:1:2 -Ga-Zn oxide can be used. Note that the atomic ratios of the oxide semiconductor films 308a and 308b and the metal oxide film 308c each include a fluctuation of plus or minus 20% of the above atomic ratio as an error.

[0148] In addition, the oxide semiconductor films 308a and 308b and the metal oxide film 308c may have, for example, a non-single crystal structure. The non-single crystal structure includes, for example, CAAC-OS (C Axis Aligned Crystalline Oxide Semiconductor) described later, a polycrystalline structure, a microcrystalline structure described later, or an amorphous structure. In the non-single crystal structure, the amorphous structure has the highest density of defect levels, and CAAC-OS has the lowest density of defect levels. Note that the oxide semiconductor films 308a and 308b and the metal oxide film 308c have the same crystallinity.

[0149] Note that the oxide semiconductor films 308a and 308b and the metal oxide film 308c may each be a mixed film having two or more of a region of an amorphous structure, a region of a microcrystalline structure, a region of a polycrystalline structure, a region of CAAC-OS, and a region of a single crystal structure. The mixed film includes, for example, a region of an amorphous structure, a region of a microcrystalline structure, a region of a polycrystalline structure, a region of CAAC-OS, and a region of a single crystal structure. There may be a case of a single-layer structure having any two or more types of regions. Further, the mixed film may have, for example, a laminated structure of any two or more types of regions among an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CAAC-OS region, and a single crystal structure region.

[0150] When silicon or carbon, which is one of the Group 14 elements, is contained in the oxide semiconductor films 308a and 308b, oxygen deficiency increases in the oxide semiconductor films 308a and 308b, and they become n-type. Therefore, the concentration of silicon or carbon (concentration obtained by secondary ion mass spectrometry) in the oxide semiconductor films 308a and 308b is set to 2×10 atoms / cm or less, preferably 2×10 18 atoms / cm 3 or less. Preferably, it is 2×10 17 atoms / cm 3 or less.

[0151] In addition, in the oxide semiconductor films 308a and 308b, the concentration of an alkali metal or an alkaline earth metal obtained by secondary ion mass spectrometry is set to 1×10 atoms / cm 18 or less, 3 preferably 2×10 atoms / cm 16 or less. When an alkali metal and an alkaline earth 3 metal are combined with an oxide semiconductor, carriers may be generated, and the off-current of the transistor may increase. Therefore, it is preferable to reduce the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor films 308a and 308b.

[0152] In addition, when nitrogen is contained in the oxide semiconductor films 308a and 308b, carriers, that is, electrons, are generated, the carrier density increases, and it easily becomes n-type. As a result, in the oxide containing nitrogen semiconductor films 308a and 308b, Transistors using semiconductors tend to have normally-on characteristics. Therefore, in the oxide semiconductor film, 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. is preferred.

[0153] As the oxide semiconductor films 308a and 308b, oxide semiconductor films with a low carrier density are used. For example, the oxide semiconductor films 308a and 308b have a carrier density of 1×10 / cm 17 or less, preferably 1×10 3 / cm 15 or less, more preferably 1×10 3 / cm 13 or less, particularly preferably less than 8×10 3 / cm 11 / cm 3 less, more preferably less than 1×10 11 / cm 3 less, more preferably less than 1×10 10 / cm 3 less, and 1×10 -9 / cm 3 or more of the oxide semiconductor film is used.

[0154] Note that it is not limited to these, and those with an appropriate composition may be used according to the semiconductor characteristics and electrical characteristics (field effect mobility, threshold voltage, etc.) of the required transistor. Also, in order to obtain the semiconductor characteristics of the required transistor, the carrier density, impurity concentration, defect density, atomic ratio of metal elements to oxygen, interatomic distance, density, etc. of the oxide semiconductor films 308a and 308b are preferably appropriate. mobility, threshold voltage, etc.) according to the required semiconductor characteristics and electrical characteristics of the transistor. Also, in order to obtain the semiconductor characteristics of the required transistor, the carrier density, impurity concentration, defect density, atomic ratio of metal elements to oxygen, interatomic distance, density, etc. of the oxide semiconductor films 308a and 308b are preferably appropriate. transistor semiconductor characteristics, the carrier density, impurity concentration, defect density, atomic ratio of metal elements to oxygen, interatomic distance, density, etc. of the oxide semiconductor films 308a and 308b are preferably appropriate. density, impurity concentration, defect density, atomic ratio of metal elements to oxygen, interatomic distance, density, etc. are preferably appropriate. is preferred.

[0155] The oxide semiconductor films 308a and 308b are in contact with films such as the insulating film 306 and the insulating film 312, which are made of materials capable of improving the interface characteristics with the oxide semiconductor film. Therefore, the oxide semiconductor films 308a and 308b function as semiconductors, and the transistor having the oxide semiconductor films 308a and 308b has excellent electrical characteristics. Since the oxide semiconductor films 308a and 308b are in contact with films made of materials that can improve the interface characteristics with the oxide semiconductor film, such as the insulating film 306 and the insulating film 312, the oxide semiconductor films 308a and 308b function as semiconductors, and the transistor having the oxide semiconductor films 308a and 308b has excellent electrical characteristics. The oxide semiconductor films 308a and 308b function as semiconductors, and the transistor having the oxide semiconductor films 308a and 308b has excellent electrical characteristics. The oxide semiconductor films 308a and 308b function as semiconductors, and the transistor having the oxide semiconductor films 308a and 308b has excellent electrical characteristics.

[0156] Note that by using an oxide semiconductor film with a low impurity concentration and a low defect level density as the oxide semiconductor films 308a and 308b, it is possible to fabricate a transistor having excellent electrical characteristics, which is preferable. Here, a low impurity concentration and a low defect level density (low oxygen deficiency) are referred to as high-purity intrinsic or substantially high-purity intrinsic. An oxide semiconductor that is high-purity intrinsic or substantially high-purity intrinsic has few carrier generation sources, so the carrier density may be reduced. Therefore, a transistor in which a channel region is formed in the oxide semiconductor film may have electrical characteristics (also referred to as normally on) in which the threshold voltage becomes negative. In addition, an oxide semiconductor film that is high-purity intrinsic or substantially high-purity intrinsic may have a low trap level density because the defect level density is low. Also, an oxide semiconductor film that is high-purity intrinsic or substantially high-purity intrinsic has an extremely small off-current, and even in an element with a channel width of 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 6 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 -13 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 μm and a channel length L of 10μm, the off-current is below the measurement limit of a semiconductor parameter analyzer, that is, 1×10 There may be cases where a transistor with small fluctuations in electrical characteristics and high reliability is obtained. Note that the charges trapped in the trap levels of the oxide semiconductor film take a long time to disappear and may behave like fixed charges. Therefore, a transistor in which a channel region is formed in an oxide semiconductor film with a high trap level density may have unstable electrical characteristics. Examples of the impurity include hydrogen, nitrogen, an alkali metal, or an alkaline earth metal.

[0157] The metal oxide film 308c is formed by processing the oxide semiconductor film formed simultaneously with the oxide semiconductor films 308a and 308b. Therefore, the metal oxide film 308c is a film having the same metal elements as the oxide semiconductor films 308a and 308b. Also, it is a film having the same crystal structure as the oxide semiconductor films 308a and 308b, or a different crystal structure. However, by introducing impurities or oxygen deficiencies into the oxide semiconductor film formed simultaneously with the oxide semiconductor films 308a and 308b, a film having conductivity is obtained, and it functions as an electrode of a capacitive element. Examples of the impurity contained in the oxide semiconductor film include hydrogen. Note that instead of hydrogen, boron, phosphorus, tin, antimony, a noble gas element, an alkali metal, an alkaline earth metal, etc. may be included. Or, the metal oxide film 308c is a film formed simultaneously with the oxide semiconductor films 308a and 308b, and oxygen deficiencies are formed due to plasma damage or the like, resulting in a film with increased conductivity. Or, the metal oxide film 308c is a film formed simultaneously with the oxide semiconductor films 308a and 308b, contains impurities, and oxygen deficiencies are formed due to plasma damage or the like, resulting in a film with increased conductivity.

[0158] Therefore, the oxide semiconductor films 308a and 308b and the metal oxide film 308c are insulating films. Specifically, the oxide semiconductor film 308a is formed over the oxide semiconductor film 306, but has a different impurity concentration. The impurity concentration of the metal oxide film 308c is higher than that of the metal oxide film 308b. The hydrogen concentration in the films 308a and 308b is 5×10 19 atoms / cm 3 Less than, good Preferably 5 x 10 18 atoms / cm 3 Less than 1 x 10 18 atoms / c m 3 Less than or equal to 5×10 17 atoms / cm 3 Below, more preferably 1× 10 16 atoms / cm 3 The hydrogen concentration in the metal oxide film 308c is 8×10 19 atoms / cm 3 More than 1×10 20 atoms / cm 3 End , more preferably 5 × 10 20 atoms / cm 3 The above is the case. In addition, the oxide semiconductor film 3 The hydrogen concentration in the metal oxide film 308c is preferably twice as high as that in the metal oxide film 308a and 308b. In most cases, it is more than 10 times higher.

[0159] In addition, the oxide semiconductor film formed at the same time as the oxide semiconductor films 308a and 308b is The oxide semiconductor film can be damaged by exposure to oxygen, and oxygen vacancies can be formed. For example, a film is formed on an oxide semiconductor film by a plasma CVD method or a sputtering method. When the oxide semiconductor film is heated, the oxide semiconductor film is exposed to plasma, and oxygen vacancies are generated. In the etching process for forming 2, the oxide semiconductor film is exposed to plasma, whereby , oxygen deficiencies are generated. Alternatively, when the oxide semiconductor film is exposed to plasma such as a mixed gas of hydrogen, rare gas, ammonia, oxygen, and hydrogen, oxygen deficiencies are generated. As a result, the oxide semiconductor film becomes highly conductive, becomes a film having conductivity, and functions as the metal oxide film 308c. That is, it can be said that the metal oxide film 308c is formed of a highly conductive oxide semiconductor film.

[0160] That is, it can also be said that the metal oxide film 308c is formed of a highly conductive metal oxide film. Also, when a silicon nitride film is used as the insulating film 314, the silicon nitride film contains hydrogen.

[0161] Therefore, when the hydrogen in the insulating film 314 diffuses into the oxide semiconductor films 308a and 308b formed simultaneously, in the oxide semiconductor film, hydrogen combines with oxygen to generate electrons, which are carriers. Also, when the silicon nitride film is formed by plasma CVD method or sputtering method, the oxide semiconductor film is exposed to plasma, and oxygen deficiencies are generated. When hydrogen contained in the silicon nitride film enters the oxygen deficiencies, electrons, which are carriers, are generated. As a result of these, the oxide semiconductor film becomes highly conductive and becomes the metal oxide film 308c.

[0162] The metal oxide film 308c has a lower resistivity than the oxide semiconductor films 308a and 308b. The resistivity of the metal oxide film 308c is preferably 1×10 -8 times or more and less than 1×10 -1 times that of the oxide semiconductor films 308a and 308b. Typically, it is 1×10 -3 Ωcm or more and 1 ×10​​​​4 less than Ω cm, more preferably, the resistivity is 1×10 -3 Ω cm or more and 1×10 -1 less than Ω cm may be sufficient.

[0163] However, one aspect of the embodiment of the present invention is not limited thereto, and the metal oxide film 308c may not be in contact with the insulating film 314 depending on the circumstances.

[0164] Further, one aspect of the embodiment of the present invention is not limited thereto, and the metal oxide film 308c may be formed in a separate process from the oxide semiconductor film 308a or 308b depending on the circumstances. In that case, the metal oxide film 308c may have a different material from the oxide semiconductor films 308a and 308b. For example, the metal oxide film 308c may be formed using indium tin oxide ( hereinafter referred to as ITO), indium zinc oxide, or the like.

[0165] In the liquid crystal display device shown in this embodiment, the capacitive element has translucency. As a result, the aperture ratio of the pixel can be increased while increasing the occupied area of the capacitive element.

[0166] The conductive films 310a, 310b, 310c, 310d, and 310e are made of a single metal such as aluminum, titanium chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten, or an alloy having this as a main component, and are used in a single-layer structure or a stacked layer structure. For example, a single-layer structure of an aluminum film containing silicon, 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, a two-layer structure in which a copper film is laminated on a copper-magnesium-aluminum alloy film, a titanium film or a nitride ​​A titanium oxide film, and an aluminum film or a copper film laminated on the titanium film or the titanium nitride film There is a three-layer structure in which a titanium film or a titanium nitride film is further 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 a molybdenum film or a molybdenum nitride film is further formed thereon There are structures such as these. In addition, a transparent conductive material containing indium oxide, tin oxide, or zinc oxide may be used.

[0167] On the insulating film 306, the oxide semiconductor films 308a, 308b, the metal oxide film 308c, and the conductive films 310a, 310b, 310c, 310d, 310e, an insulating film 53, namely, an insulating film 312 and an insulating film 314 are formed. The insulating film 312 is preferably formed of a material capable of improving the interfacial characteristics with the oxide semiconductor film, similarly to the insulating film 306, and can be formed using an oxide insulating film. Here, as the insulating film 312, an insulating film 312a and an insulating film 312b are laminated to form it.

[0168] The insulating film 312a is an oxide insulating film that permeates oxygen. The insulating film 312a also functions as a damage relaxation film for the oxide semiconductor films 308a, 308b, and the metal oxide film 308c when forming the insulating film 312b to be formed later.

[0169] As the insulating film 312a, a silicon oxide film, a silicon oxynitride film, etc. with a thickness of 5 nm or more and 150 nm or less, preferably 5 nm or more and 50 nm or less can be used. In this specification, the silicon oxynitride film means that, as its composition, the oxygen content is higher than that of nitrogen Refers to a film, and a silicon oxynitride film has a higher nitrogen content than oxygen content in terms of its composition. Refers to a film.

[0170] Also, the insulating film 312a is an oxide insulating film, and the oxide insulating film preferably contains nitrogen and has few defects.

[0171] Typical examples of oxide insulating films that contain nitrogen and have few defects include silicon oxynitride films, aluminum oxynitride films, etc.

[0172] An oxide insulating film with few defects has a first signal with a g value of 2.037 or more and 2.039 or less, a second signal with a g value of 2.001 or more and 2. 003 or less, and a third signal with a g value of 1.964 or more and 1.966 or less in the spectrum obtained by measurement with an ESR of 100K or less. Note that the split width of the first signal and the second signal, and the split width of the second signal and the third signal are about 5m T in X-band ESR measurement. Also, the sum of the spin densities of the first signal with a g value of 2.037 or more and 2.039 or less, the second signal with a g value of 2. 01 or more and 2.003 or less, and the third signal with a g value of 1.964 or more and 1.966 or less is 1×10 spins / cm less than 18 3 spins / cm 3 and typically is 1×10 17 spins / cm 3 3 18 18 spins / cm 3 less than

[0173] Note that in the ESR spectrum at 100K or less, the first signal with a g value of 2.037 or more and 2.039 or less, the second signal with a g value of 2.001 or more and 2.003 or less, and the g value of 1. ​ The third signal, which is 1.964 or more and 1.966 or less, corresponds to a signal caused by nitrogen oxides (NOx, where x is 0 or more and 2 or less , preferably 1 or more and 2 or less). Representative examples of nitrogen oxides include nitric oxide, nitrogen dioxide, and the like. That is, the first signal with a g value of 2.037 or more and 2.039 or less, the second signal with a g value of 2.001 or more and 2.003 or less, and the third signal with a g value of 1.96 4 or more and 1.966 or less, the smaller the total spin density of the third signal, the lower the content of nitrogen oxides contained in the oxide insulating film can be said to be.

[0174] When the insulating film 312a has a low content of nitrogen oxides as described above, it is possible to reduce carrier trapping at the interface between the insulating film 312a and the oxide semiconductor film. As a result, it is possible to reduce the shift of the threshold voltage of the transistors included in the display device and reduce the variation in the electrical characteristics of the transistors.

[0175] In addition, the insulating film 312a preferably has a nitrogen concentration of 6 × 10 or less measured by SIMS (Secondary Ion Mass Spec 20 trometry) in atoms / cm 3 . As a result, in the insulating film 312a, it becomes difficult to generate nitrogen oxides , and it is possible to reduce carrier trapping at the interface between the insulating film 312a and the oxide semiconductor films 308a and 308b. Also, it is possible to reduce the shift of the threshold voltage of the transistors included in the display device, and reduce the variation in the electrical characteristics of the transistors . .

[0176] Note that when the insulating film 312a contains nitrogen oxides and ammonia in the film, the manufacturing process In the heat treatment process of the process, nitrogen oxides and ammonia react, and the nitrogen oxides are desorbed as nitrogen gas. As a result, the nitrogen concentration and the nitrogen oxide content of the insulating film 312a can be reduced. Further, it is possible to reduce the carrier traps at the interface between the insulating film 312a and the oxide semiconductor films 308a and 308b. Further, it is possible to reduce the shift of the threshold voltage of the transistor included in the display device, and it is possible to reduce the variation in the electrical characteristics of the transistor. In the insulating film 312a, all the oxygen that has entered the insulating film 312a from the outside does not move outside the insulating film 312a, and there is also oxygen remaining in the insulating film 312a. Further, oxygen enters the insulating film 312a, and oxygen contained in the insulating film 312a moves outside the insulating film 312a, so that oxygen movement may occur in the insulating film 312a. When an oxide insulating film that permeates oxygen is formed as the insulating film 312a, oxygen desorbed from the insulating film 312b provided on the insulating film 312a can be moved to the oxide semiconductor films 308a and 308b through the insulating film 312a. The insulating film 312b is formed so as to be in contact with the insulating film 312a. The insulating film 312b is formed using an oxide insulating film containing more oxygen than oxygen satisfying the stoichiometric composition. The oxide insulating film containing more oxygen than oxygen satisfying the stoichiometric composition desorbs a part of oxygen by heating. The oxide insulating film containing more oxygen than oxygen satisfying the stoichiometric composition has an oxygen desorption amount of 1.0×10 atoms / cm when converted to oxygen atoms in the TDS analysis.

[0177] In the insulating film 312a, all the oxygen that has entered the insulating film 312a from the outside does not move outside the insulating film 312a, and there is also oxygen remaining in the insulating film 312a. Further, oxygen enters the insulating film 312a, and oxygen contained in the insulating film 312a moves outside the insulating film 312a, so that oxygen movement may occur in the insulating film 312a. In the insulating film 312a, all the oxygen that has entered the insulating film 312a from the outside does not move outside the insulating film 312a, and there is also oxygen remaining in the insulating film 312a. Further, oxygen enters the insulating film 312a, and oxygen contained in the insulating film 312a moves outside the insulating film 312a, so that oxygen movement may occur in the insulating film 312a. In the insulating film 312a, all the oxygen that has entered the insulating film 312a from the outside does not move outside the insulating film 312a, and there is also oxygen remaining in the insulating film 312a. Further, oxygen enters the insulating film 312a, and oxygen contained in the insulating film 312a moves outside the insulating film 312a, so that oxygen movement may occur in the insulating film 312a. In the insulating film 312a, all the oxygen that has entered the insulating film 312a from the outside does not move outside the insulating film 312a, and there is also oxygen remaining in the insulating film 312a. Further, oxygen enters the insulating film 312a, and oxygen contained in the insulating film 312a moves outside the insulating film 312a, so that oxygen movement may occur in the insulating film 312a.

[0178] When an oxide insulating film that permeates oxygen is formed as the insulating film 312a, oxygen desorbed from the insulating film 312b provided on the insulating film 312a can be moved to the oxide semiconductor films 308a and 308b through the insulating film 312a. When an oxide insulating film that permeates oxygen is formed as the insulating film 312a, oxygen desorbed from the insulating film 312b provided on the insulating film 312a can be moved to the oxide semiconductor films 308a and 308b through the insulating film 312a. When an oxide insulating film that permeates oxygen is formed as the insulating film 312a, oxygen desorbed from the insulating film 312b provided on the insulating film 312a can be moved to the oxide semiconductor films 308a and 308b through the insulating film 312a.

[0179] The insulating film 312b is formed so as to be in contact with the insulating film 312a. The insulating film 312b is formed using an oxide insulating film containing more oxygen than oxygen satisfying the stoichiometric composition. The oxide insulating film containing more oxygen than oxygen satisfying the stoichiometric composition desorbs a part of oxygen by heating. The oxide insulating film containing more oxygen than oxygen satisfying the stoichiometric composition has an oxygen desorption amount of 1.0×10 atoms / cm when converted to oxygen atoms in the TDS analysis. The oxide insulating film containing more oxygen than oxygen satisfying the stoichiometric composition desorbs a part of oxygen by heating. The oxide insulating film containing more oxygen than oxygen satisfying the stoichiometric composition has an oxygen desorption amount of 1.0×10 atoms / cm 18 when converted to oxygen atoms in the TDS analysis.3 Preferably, it is 3.0×10 20 atoms / cm 3 or more of the oxide insulating film. In addition, the surface temperature of the film during the above TDS analysis is 100°C or higher and 700°C or lower, and is preferably in the range of 100°C or higher and 500°C or lower.

[0180] As the insulating film 312b, silicon oxide, silicon oxynitride, etc. with a thickness of 30 nm or more and 500 nm or less, preferably 50 nm or more and 400 nm or less can be used.

[0181] In addition, the insulating film 312b preferably has a small amount of defects. Typically, by ESR measurement, the spin density of the signal appearing at g = 2.001 derived from the dangling bonds of silicon is 1.5×10 18 spins / cm 3 less than, and more preferably 1×10 18 spins / cm 3 or less. Note that since the insulating film 312b is separated from the oxide semiconductor films 308a and 308b, it may have a higher defect density than the insulating film 312a.

[0182] As the insulating film 314, by providing a nitride insulating film having a blocking effect on oxygen, hydrogen, water, alkali metals, alkaline earth metals, etc., diffusion of oxygen from the oxide semiconductor films 308a, 308b, and the metal oxide film 308c to the outside can be prevented. As the nitride insulating film there are silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, etc.

[0183] In addition, having a blocking effect on oxygen, hydrogen, water, alkali metals, alkaline earth metals, etc. ​​​An oxide insulating film having a blocking effect against oxygen, hydrogen, water, etc. may be provided on the nitride insulating film. Examples of the oxide insulating film having a blocking effect against oxygen, hydrogen, water, etc. include aluminum oxide, aluminum oxynitride, gallium oxide, gallium oxynitride, yttrium oxide, yttrium oxynitride, hafnium oxide, hafnium oxynitride, etc. Further, in order to control the capacitance value of the capacitor element, a nitride insulating film or an oxide insulating film may be appropriately provided on the nitride insulating film having a blocking effect against oxygen, hydrogen, water, alkali metal, alkaline earth metal, etc.

[0184] Also, a conductive film 316b is formed on the insulating film 314. The conductive film 316b is formed on the insulating film 314 and can function as an electrode of the capacitor element.

[0185] The conductive film 316b can be formed using a conductive material having translucency. Examples of the conductive material having translucency include 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, etc.

[0186] As the organic insulating film 317, organic resins such as acrylic resin, polyimide, and epoxy resin can be used. Note that the organic insulating film 317 has a thickness of 500 nm or more and 5000 nm or less, preferably 1000 nm or more and 3000 nm or less. By setting the thickness of the organic insulating film 317 to the above thickness, it is possible to fill the concave portion on the conductive film 316b with the organic insulating film 317, and it is possible to reduce the unevenness in the region where the alignment film 320 is formed. ​​​​​​​​​​​​

[0187] By forming the organic insulating film 317 using an organic resin, at least the recesses of the conductive film 316b can be filled with the organic insulating film 317, and the alignment unevenness of the liquid crystal material constituting the liquid crystal layer 321 can be reduced.

[0188] Also, conductive films 319 and 319a are formed on the organic insulating film 317. The conductive film 31 9 functions as a pixel electrode. The conductive film 319a is electrically connected to the conductive film 304b in the opening 364a (see Fig. 9(A).) and is electrically connected to the conductive film 310c in the opening 364b (see Fig. 9(A).). That is, it functions as a connection electrode connecting the conductive film 304b and the conductive film 310c.

[0189] The organic insulating film 317 is not limited to this. For example, the organic insulating film 317 can also have the function of a color filter or a black matrix. For example, when the organic insulating film 31 7 has the function of a color filter, for example, an organic insulating film 317 having colorability can be formed for each color according to the red pixel, blue pixel, and green pixel.

[0190] The conductive films 319 and 319a can be formed using a conductive material having translucency similarly to the conductive film 316b.

[0191] Note that, in order to have a connection structure in which the conductive film 304b and the conductive film 310c are in direct contact, before forming the conductive film 310c, in order to form openings in the insulating films 305 and 306, it is necessary to form a mask for patterning. However, as shown in Fig. 4, by connecting the conductive film 304b and the conductive film 310c with the conductive film 319a, the conductive film 304b and there is no need to fabricate a connection portion where the conductive film 310c is in direct contact, and the number of photomasks can be reduced by one. That is, it is possible to reduce the manufacturing process of the liquid crystal display device.

[0192] The alignment film 320 desirably has light transmissivity, and typically, an organic resin such as an acrylic resin, a polyimide, or an epoxy resin can be used.

[0193] Further, a film having colorability (hereinafter referred to as a colored film 346) is formed on the substrate 342. The colored film 346 functions as a color filter. Further, a light-shielding film 344 adjacent to the colored film 346 is formed on the substrate 342. The light-shielding film 344 functions as a black matrix. Further, the colored film 346 is not necessarily provided. For example, when the liquid crystal display device is black and white, etc., the colored film 346 may not be provided.

[0194] The colored film 346 may be a colored film that transmits light in a specific wavelength band. 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. Or as the colored film 346, a light-transmitting layer that transmits the light of the light source as it is can be used. For example, as the light-transmitting layer, an organic resin such as an acrylic resin, a polyimide, or an epoxy resin can be used.

[0195] The light-shielding film 344 only needs to have a function of shielding light in a specific wavelength band, and a metal film or an organic insulating film containing a black pigment or the like can be used.

[0196] ​​​​​​​​​ Further, an insulating film 348 is formed on the colored film 346. The insulating film 348 functions as a planarization layer or suppresses the diffusion of impurities that the colored film 346 may contain to the liquid crystal element side. It has the function of doing so.

[0197] Further, a conductive film 350 is formed on the insulating film 348. The conductive film 350 functions as the other of a pair of electrodes that the liquid crystal element in the pixel portion has. Note that an alignment film 320 is formed on the conductive films 319 and 319 a, and an alignment film 352 is formed on the conductive film 350.

[0198] Further, a liquid crystal layer 321 is formed between the conductive films 319, 319a and the conductive film 350. Also, the liquid crystal layer 321 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 suppresses the entry of moisture and the like from the outside and comes into contact with an inorganic material.

[0199]

[0200] Further, a spacer for maintaining the thickness (also referred to as cell gap) of the liquid crystal layer 321 may be provided between the conductive films 319, 319a and the conductive film 350.

[0200] A method for manufacturing the element portion provided on the substrate 302 shown in the liquid crystal display device shown in FIG. 4 will be described with reference to FIGS. 5 to 8. Here, the element portion provided on the substrate 302 refers to the region sandwiched between the substrate 302 and the alignment film 320.

[0201] The films (insulating film, oxide semiconductor film, metal oxide film, conductive film, etc.) constituting the transistor can be formed using a photolithography method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD ) method. Alternatively, they can be formed by a coating method or a printing method. ) method. Alternatively, they can be formed by a coating method or a printing method. As film formation methods, sputtering method and plasma enhanced chemical vapor deposition (PECVD) method are typical , but thermal CVD method may also be used. As an example of thermal CVD method, MOCVD (metalorganic chemical vapor deposition) method or ALD (atomic layer deposition) method may be used.

[0202] In the thermal CVD method, a source gas and an oxidant are simultaneously fed into the chamber, and the pressure in the chamber is set to atmospheric pressure or under reduced pressure, and the reaction is carried out near or on the substrate to deposit a film on the substrate. Thus, since the thermal CVD method is a film formation method that does not generate plasma, it has the advantage that defects are not generated due to plasma damage.

[0203] Also, in the ALD method, the pressure in the chamber is set to atmospheric pressure or under reduced pressure, and source gases for reaction are sequentially introduced into the chamber, and film formation may be carried out by repeating the order of gas introduction. For example, by switching each switching valve (also called a high-speed valve), two or more types of source gases are sequentially supplied to the chamber, and an inert gas (such as argon or nitrogen) etc. is introduced simultaneously with or after the first source gas so that the plurality of types of source gases do not mix, and the second source gas is introduced. When an inert gas is introduced simultaneously, the inert gas serves as a carrier gas, and an inert gas may also be introduced simultaneously when the second source gas is introduced. Also, instead of introducing an inert gas, after evacuating the first source gas by vacuum exhaust, the second source gas may be introduced. The first source gas is adsorbed on the surface of the substrate to form the first layer, and reacts with the second source gas introduced later, and the second layer is laminated on the first layer to form a thin film.

[0204] By repeating a plurality of times until the desired thickness is achieved while controlling this gas introduction order, step coverage excellent thin films can be formed. The thickness of the thin film can be adjusted according to the number of times the gas introduction order is repeated, so precise film thickness adjustment is possible, making it suitable for manufacturing fine transistors .

[0205] First, a substrate 302 is prepared. Here, a glass substrate is used as the substrate 302

[0206] Next, a conductive film is formed on the substrate 302, and by processing the conductive film into a desired shape, conductive films 304a, 304b, and 304c are formed. Note that the formation of the conductive films 304a, 304b, and 304c can be achieved by forming a mask by first patterning in a desired region and etching the region not covered by the mask .

[0207] Also, as the conductive films 304a, 304b, and 304c, typically, they can be formed using a sputtering method , a vacuum evaporation method, a pulsed laser deposition (PLD) method, a thermal CVD method, etc .

[0208] Also, tungsten films can be formed as the conductive films 304a, 304b, and 304c using a film forming apparatus that utilizes ALD . In this case, WF 6 gas and B 2 H 6 gas are sequentially introduced repeatedly to form an initial tungsten film, and then WF gas and H 6 gas are introduced simultaneously to form a tungsten film. Note that instead of B 2 H gas, SiH 2 H 6 gas can also be used 4 .

[0209] ​ Next, an insulating film 305 is formed on the substrate 302 and the conductive films 304a, 304b, and 304c. Then, an insulating film 306 is formed on the insulating film 305 (see Fig. 5(A)).

[0210] The insulating film 305 and the insulating film 306 can be formed by a sputtering method, a CVD method, a vacuum evaporation method, a pulse laser deposition (PLD) method, a thermal CVD method, or the like. It is preferable that the insulating film 305 and the insulating film 306 are continuously formed in a vacuum to suppress the inclusion of impurities. When forming a silicon oxide film or a silicon oxynitride film as the insulating film 305 and the insulating film 306, it is preferable to use a deposition gas containing silicon and an oxidizing gas as the source gases. Representative examples of the deposition gas containing silicon include silane, disilane, trisilane, and silane fluoride. Examples of the oxidizing gas include oxygen, ozone, nitrous oxide, and nitrogen dioxide. When forming a gallium oxide film as the insulating film 305 and the insulating film 306, it can be formed using a MOCVD (Metal Organic Chemical Vapor Deposition) method.

[0211] When forming a hafnium oxide film as the insulating film 305 and the insulating film 306 using a thermal CVD method such as the MOCVD method or the ALD method, a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide solution, typically tetrakis(dimethylamido)hafnium (TDMAH)) and ozone (O) as an oxidizing agent are used. The chemical formula of tetrakis(dimethylamido)hafnium is Hf[N(CH When forming a silicon oxide film or a silicon oxynitride film as the insulating film 305 and the insulating film 306, it is preferable to use a deposition gas containing silicon and an oxidizing gas as the source gases. Representative examples of the deposition gas containing silicon include silane, disilane, trisilane, and silane fluoride. Examples of the oxidizing gas include oxygen, ozone, nitrous oxide, and nitrogen dioxide. When forming a gallium oxide film as the insulating film 305 and the insulating film 306, it can be formed using a MOCVD (Metal Organic Chemical Vapor Deposition) method. When forming a hafnium oxide film as the insulating film 305 and the insulating film 306 using a thermal CVD method such as the MOCVD method or the ALD method, a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide solution, typically tetrakis(dimethylamido)hafnium (TDMAH)) and ozone (O) as an oxidizing agent are used. The chemical formula of tetrakis(dimethylamido)hafnium is Hf[N(CH When forming a gallium oxide film as the insulating film 305 and the insulating film 306, it can be formed using a MOCVD (Metal Organic Chemical Vapor Deposition) method.

[0212] When forming a gallium oxide film as the insulating film 305 and the insulating film 306, it can be formed using a MOCVD (Metal Organic Chemical Vapor Deposition) method. (Metal Organic Chemical Vapor Deposition ) method.

[0213] When forming a hafnium oxide film as the insulating film 305 and the insulating film 306 using a thermal CVD method such as the MOCVD method or the ALD method, a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide solution, typically tetrakis(dimethylamido)hafnium (TDMAH)) and ozone (O) as an oxidizing agent are used. The chemical formula of tetrakis(dimethylamido)hafnium is Hf[N(CH When forming a hafnium oxide film as the insulating film 305 and the insulating film 306 using a thermal CVD method such as the MOCVD method or the ALD method, a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide solution, typically tetrakis(dimethylamido)hafnium (TDMAH)) and ozone (O) as an oxidizing agent are used. The chemical formula of tetrakis(dimethylamido)hafnium is Hf[N(CH When forming a hafnium oxide film as the insulating film 305 and the insulating film 306 using a thermal CVD method such as the MOCVD method or the ALD method, a source gas obtained by vaporizing a liquid containing a solvent and a hafnium precursor compound (hafnium alkoxide solution, typically tetrakis(dimethylamido)hafnium (TDMAH)) and ozone (O) as an oxidizing agent are used. The chemical formula of tetrakis(dimethylamido)hafnium is Hf[N(CH TDMAH)) are used. The chemical formula of tetrakis(dimethylamido)hafnium is Hf[N(CH 3 ) of two types of gases are used. The chemical formula of tetrakis(dimethylamido)hafnium is Hf[N(CH3 ) 2 4 That is. Also, as other material liquids, there are tetrakis(ethylmethylamide)hafnium and the like.

[0214] Also, when forming an aluminum oxide film using a thermal CVD method such as MOCVD or ALD as the insulating films 305 and 306, a raw material gas obtained by vaporizing a liquid containing a solvent and an aluminum precursor compound (such as trimethylaluminum (TMA)) and an oxidizing agent are used. Note that the chemical formula of trimethylaluminum is Al(C H ) 2 3. Also, as other material liquids, there are tris(dimethylamide)aluminum, H 3 ) 3 triisobutylaluminum, aluminum tris(2,2,6,6-tetramethyl-3 ,5-heptanedionate), and the like.

[0215] Also, when forming a silicon oxide film using a thermal CVD method such as MOCVD or ALD as the insulating films 305 and 306, hexachlorodisilane is adsorbed on the film-forming surface, chlorine contained in the adsorbate is removed, and radicals of an oxidizing gas (O 2, nitrous oxide) 2 are supplied and reacted with the adsorbate.

[0216] Next, an oxide semiconductor film 307 is formed on the insulating film 306 (see FIG. 5(B)).

[0217] The oxide semiconductor film 307 can be formed using a sputtering method, a coating method, a pulsed laser deposition method, a laser ablation method, a thermal CVD method, or the like.

[0218] ​The sputtering gas is a rare gas (typically argon), oxygen, or a mixture of a rare gas and oxygen. In the case of a mixture of rare gas and oxygen, the gas ratio of oxygen to rare gas is It is preferable to increase

[0219] Further, the target may be appropriately selected depending on the composition of the oxide semiconductor film to be formed.

[0220] Note that when the oxide semiconductor film is formed by, for example, a sputtering method, the substrate temperature The temperature is 150° C. or higher and 750° C. or lower, preferably 150° C. or higher and 450° C. or lower, and more preferably The oxide semiconductor film is formed at a temperature of 200° C. or higher and 350° C. or lower. A film can be formed.

[0221] In addition, the following conditions are preferably applied to form the CAAC-OS film.

[0222] By suppressing the inclusion of impurities during film formation, it is possible to prevent the crystal state from being destroyed by impurities. For example, the concentration of impurities (hydrogen, water, carbon dioxide, nitrogen, etc.) present in the film formation chamber can be reduced. In addition, the impurity concentration in the deposition gas may be reduced. A deposition gas having a temperature of 80° C. or less, preferably −100° C. or less, is used.

[0223] Using a deposition system that utilizes ALD, an oxide semiconductor film, such as an In-Ga-Zn-O film, is formed. In this case, In(CH 3 ) 3 Gas and O 3 The gas is introduced repeatedly to form an In-O layer. Then, Ga(CH 3 ) 3 Gas and O 3 Gases are introduced simultaneously to form a GaO layer, and then Then Zn(CH3 ) 2 and O 3 gases are simultaneously introduced to form a ZnO layer. Note that the order of these layers is not limited to this example. Also, these gases may be mixed to form a mixed compound layer such as an In-Ga-O layer, an In -Zn-O layer, or a Ga-Zn-O layer. Note that instead of O gas, H 3 gas bubbled with an inert gas such as Ar may be used, but it is preferable to use O 2 gas that does not contain H. Also, instead of In(CH 3 ) 3 ) 3 gas, In(C 2 H 5 ) 3 gas may be used. Also, instead of Ga(CH 3 ) 3 gas, Ga(C 2 H 5 ) 3 gas may be used. Also, Zn(CH 3 ) 2 gas may be used.

[0224] Next, by processing the oxide semiconductor film 307 into a desired shape, island-shaped oxide semiconductor films 30 8a, 308b, and 308d are formed. Note that the formation of the oxide semiconductor films 308a, 308b, and 30 8d can be achieved by forming a mask by second patterning 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 (see Fig. 5(C)). (See Fig. 5(C).)

[0225] Note that after this, a heat treatment is performed to remove impurities contained in the oxide semiconductor films 308a, 308b, and 308d. ​Hydrogen, water, etc. that can be desorbed are removed, and the hydrogen concentration and water concentration contained in the oxide semiconductor films 308a, 308b, and 308d may be reduced. As a result, highly purified oxide semiconductor films 308a, 308b, and 308d can be formed. The temperature of the heat treatment is typically 250°C or higher and 650°C or lower, preferably 300°C or higher and 500°C or lower. Note that the temperature of the heat treatment is typically 300°C or higher and 400°C or lower, preferably 320°C or higher and 370°C or lower. By setting the temperature in this range, it is possible to reduce warping and shrinkage of the substrate even in a large-area substrate, and the yield can be improved. The heat treatment can be performed using an electric furnace, an RTA apparatus, etc. By using an RTA apparatus, heat treatment can be performed at a temperature equal to or higher than the distortion point of the substrate for a limited time. Therefore, it is possible to shorten the heat treatment time and reduce warping of the substrate during the heat treatment, which is particularly preferable for a large-area substrate. The heat treatment can be performed in an atmosphere of nitrogen, oxygen, ultra-dry air (air with a water content of 20 ppm or less, preferably 1 ppm or less, more preferably 10 ppb or less), or a noble gas (argon, helium, etc.). It is preferable that the above nitrogen, oxygen, ultra-dry air, or noble gas does not contain hydrogen, water, etc. Further, after heat treatment in a nitrogen or noble gas atmosphere, heat treatment may be performed in an oxygen or ultra-dry air atmosphere. As a result, hydrogen, water, etc. contained in the oxide semiconductor film can be desorbed, and oxygen can be supplied to the oxide semiconductor film. As a result, the amount of oxygen vacancies contained in the oxide semiconductor film can be reduced. The temperature of the heat treatment is typically 250°C or higher and 650°C or lower, preferably 300°C or higher and 500°C or lower. Note that the temperature of the heat treatment is typically 300°C or higher and 400°C or lower, preferably 320°C or higher and 370°C or lower. By setting the temperature in this range, it is possible to reduce warping and shrinkage of the substrate even in a large-area substrate, and the yield can be improved. The heat treatment can be performed using an electric furnace, an RTA apparatus, etc. By using an RTA apparatus, heat treatment can be performed at a temperature equal to or higher than the distortion point of the substrate for a limited time. Therefore, it is possible to shorten the heat treatment time and reduce warping of the substrate during the heat treatment, which is particularly preferable for a large-area substrate. The heat treatment can be performed in an atmosphere of nitrogen, oxygen, ultra-dry air (air with a water content of 20 ppm or less, preferably 1 ppm or less, more preferably 10 ppb or less), or a noble gas (argon, helium, etc.). It is preferable that the above nitrogen, oxygen, ultra-dry air, or noble gas does not contain hydrogen, water, etc. Further, after heat treatment in a nitrogen or noble gas atmosphere, heat treatment may be performed in an oxygen or ultra-dry air atmosphere. As a result, hydrogen, water, etc. contained in the oxide semiconductor film can be desorbed, and oxygen can be supplied to the oxide semiconductor film. As a result, the amount of oxygen vacancies contained in the oxide semiconductor film can be reduced. The temperature of the heat treatment is typically 250°C or higher and 650°C or lower, preferably 300°C or higher and 500°C or lower. Note that the temperature of the heat treatment is typically 300°C or higher and 400°C or lower, preferably 320°C or higher and 370°C or lower. By setting the temperature in this range, it is possible to reduce warping and shrinkage of the substrate even in a large-area substrate, and the yield can be improved.

[0226] The heat treatment can be performed using an electric furnace, an RTA apparatus, etc. By using an RTA apparatus, heat treatment can be performed at a temperature equal to or higher than the distortion point of the substrate for a limited time. Therefore, it is possible to shorten the heat treatment time and reduce warping of the substrate during the heat treatment, which is particularly preferable for a large-area substrate. The heat treatment can be performed in an atmosphere of nitrogen, oxygen, ultra-dry air (air with a water content of 20 ppm or less, preferably 1 ppm or less, more preferably 10 ppb or less), or a noble gas (argon, helium, etc.). It is preferable that the above nitrogen, oxygen, ultra-dry air, or noble gas does not contain hydrogen, water, etc. Further, after heat treatment in a nitrogen or noble gas atmosphere, heat treatment may be performed in an oxygen or ultra-dry air atmosphere. As a result, hydrogen, water, etc. contained in the oxide semiconductor film can be desorbed, and oxygen can be supplied to the oxide semiconductor film. As a result, the amount of oxygen vacancies contained in the oxide semiconductor film can be reduced. The temperature of the heat treatment is typically 250°C or higher and 650°C or lower, preferably 300°C or higher and 500°C or lower. Note that the temperature of the heat treatment is typically 300°C or higher and 400°C or lower, preferably 320°C or higher and 370°C or lower. By setting the temperature in this range, it is possible to reduce warping and shrinkage of the substrate even in a large-area substrate, and the yield can be improved. The heat treatment can be performed using an electric furnace, an RTA apparatus, etc. By using an RTA apparatus, heat treatment can be performed at a temperature equal to or higher than the distortion point of the substrate for a limited time. Therefore, it is possible to shorten the heat treatment time and reduce warping of the substrate during the heat treatment, which is particularly preferable for a large-area substrate.

[0227] The heat treatment can be performed in an atmosphere of nitrogen, oxygen, ultra-dry air (air with a water content of 20 ppm or less, preferably 1 ppm or less, more preferably 10 ppb or less), or a noble gas (argon, helium, etc.). It is preferable that the above nitrogen, oxygen, ultra-dry air, or noble gas does not contain hydrogen, water, etc. Further, after heat treatment in a nitrogen or noble gas atmosphere, heat treatment may be performed in an oxygen or ultra-dry air atmosphere. As a result, hydrogen, water, etc. contained in the oxide semiconductor film can be desorbed, and oxygen can be supplied to the oxide semiconductor film. As a result, the amount of oxygen vacancies contained in the oxide semiconductor film can be reduced. The heat treatment can be performed using an electric furnace, an RTA apparatus, etc. By using an RTA apparatus, heat treatment can be performed at a temperature equal to or higher than the distortion point of the substrate for a limited time. Therefore, it is possible to shorten the heat treatment time and reduce warping of the substrate during the heat treatment, which is particularly preferable for a large-area substrate. The heat treatment can be performed in an atmosphere of nitrogen, oxygen, ultra-dry air (air with a water content of 20 ppm or less, preferably 1 ppm or less, more preferably 10 ppb or less), or a noble gas (argon, helium, etc.). It is preferable that the above nitrogen, oxygen, ultra-dry air, or noble gas does not contain hydrogen, water, etc. Further, after heat treatment in a nitrogen or noble gas atmosphere, heat treatment may be performed in an oxygen or ultra-dry air atmosphere. As a result, hydrogen, water, etc. contained in the oxide semiconductor film can be desorbed, and oxygen can be supplied to the oxide semiconductor film. As a result, the amount of oxygen vacancies contained in the oxide semiconductor film can be reduced. The heat treatment can be performed using an electric furnace, an RTA apparatus, etc. By using an RTA apparatus, heat treatment can be performed at a temperature equal to or higher than the distortion point of the substrate for a limited time. Therefore, it is possible to shorten the heat treatment time and reduce warping of the substrate during the heat treatment, which is particularly preferable for a large-area substrate. The heat treatment can be performed in an atmosphere of nitrogen, oxygen, ultra-dry air (air with a water content of 20 ppm or less, preferably 1 ppm or less, more preferably 10 ppb or less), or a noble gas (argon, helium, etc.). It is preferable that the above nitrogen, oxygen, ultra-dry air, or noble gas does not contain hydrogen, water, etc. Further, after heat treatment in a nitrogen or noble gas atmosphere, heat treatment may be performed in an oxygen or ultra-dry air atmosphere. As a result, hydrogen, water, etc. contained in the oxide semiconductor film can be desorbed, and oxygen can be supplied to the oxide semiconductor film. As a result, the amount of oxygen vacancies contained in the oxide semiconductor film can be reduced. The heat treatment can be performed using an electric furnace, an RTA apparatus, etc. By using an RTA apparatus, heat treatment can be performed at a temperature equal to or higher than the distortion point of the substrate for a limited time. Therefore, it is possible to shorten the heat treatment time and reduce warping of the substrate during the heat treatment, which is particularly preferable for a large-area substrate. The heat treatment can be performed in an atmosphere of nitrogen, oxygen, ultra-dry air (air with a water content of 20 ppm or less, preferably 1 ppm or less, more preferably 10 ppb or less), or a noble gas (argon, helium, etc.). It is preferable that the above nitrogen, oxygen, ultra-dry air, or noble gas does not contain hydrogen, water, etc. Further, after heat treatment in a nitrogen or noble gas atmosphere, heat treatment may be performed in an oxygen or ultra-dry air atmosphere. As a result, hydrogen, water, etc. contained in the oxide semiconductor film can be desorbed, and oxygen can be supplied to the oxide semiconductor film. As a result, the amount of oxygen vacancies contained in the oxide semiconductor film can be reduced.

[0228] When the film formation temperature of the insulating film 311a to be formed later is set to 280°C or higher and 400°C or lower it is possible to desorb hydrogen, water, etc. contained in the oxide semiconductor films 308a, 308b, and 308d so that this heat treatment is unnecessary.

[0229] Next, a conductive film 30 9 is formed on the insulating film 306 and the oxide semiconductor films 308a, 308b, and 308d (see Fig. 6(A)).

[0230] As the conductive film 309, it can be formed using a sputtering method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, a thermal CVD method, or the like.

[0231] Next, by processing the conductive film 309 into a desired shape, conductive films 310a, 310b, 310 c, 310d, and 310e are formed. Note that the formation of the conductive films 310a, 310b, 310c, 31 0d, and 310e can be performed by forming a mask by a third patterning in a desired region and etching the region not covered by the mask (see Fig. 6( B)).

[0232] Next, an insulating film 311 in which insulating films 311a and 311 b are laminated is formed so as to cover the insulating film 306, the oxide semiconductor films 308a, 308b, 308d, and the conductive films 310 a, 310b, 310c, 310d, and 310e (see Fig. 6(C)). The insulating film 311 can be formed using a sputtering method, a CVD method, an evaporation method, or the like.

[0233] Note that after forming the insulating film 311a, it is preferable to continuously form the insulating film 311b without exposing it to the atmosphere. After forming the insulating film 311a, without opening to the atmosphere, the flow rate of the source gas, ​Adjust one or more of pressure, high-frequency power, and substrate temperature to continuously form the insulating film 311b. By doing so, the impurity concentration derived from atmospheric components at the interface between the insulating films 311a and 311b can be reduced. At the same time, oxygen contained in the insulating film 311b can be moved to the oxide semiconductor films 308a, 308 b, 308d, and the oxygen deficiency amount of the oxide semiconductor films 308a, 308b, 30 8d can be reduced.

[0234] As the insulating film 311a, the oxidizing gas with respect to the depositable gas is more than 20 times and less than 100 times preferably 40 times or more and 80 times or less, and the pressure in the processing chamber is less than 100 Pa, preferably 50 Pa or less. By using the CVD method, an oxide insulating film containing nitrogen and having a small defect amount can be formed.

[0235] As the source gas for the insulating film 311a, it is preferable to use a depositable gas containing silicon and an oxidizing gas. Typical examples of the depositable gas containing silicon include silane, disilane, tri silane, silane fluoride, etc. Examples of the oxidizing gas include oxygen, ozone, nitrous oxide, and two nitrogen oxides, etc.

[0236] By using the above conditions, an oxide insulating film that permeates oxygen can be formed as the insulating film 311a. In addition, by providing the insulating film 311a, damage to the oxide semiconductor films 308a, 308b, 308d can be reduced in the forming process of the insulating film 311b formed later.

[0237] As the insulating film 311b, the substrate placed in the evacuated processing chamber of the plasma CVD apparatus is maintained at 180°C or higher and 280°C or lower, more preferably 200°C or higher and 240°C or lower. Introduce the source gas into the processing chamber and set the pressure in the processing chamber to be 100 Pa or more and 250 Pa or less, and more preferably 100 Pa or more and 200 Pa or less. Apply a high-frequency power of 0.1 7 W / cm or more and 0.5 W / cm 2 or less, and more preferably 0.25 W / cm 2 or more and 0. 2 35 W / cm or less to form a silicon oxide film or a silicon oxynitride film under the condition of supplying the high-frequency power. 2

[0238] As the source gas for the insulating film 311b, it is preferable to use a depositable gas containing silicon and an oxidizing gas. Representative examples of the depositable gas containing silicon include silane, disilane, tri silane, silane fluoride, etc. Examples of the oxidizing gas include oxygen, ozone, nitrous oxide, and nitrogen dioxide, etc.

[0239] As the film formation conditions for the insulating film 311b, by supplying the high-frequency power of the above power density in the reaction chamber of the above pressure, the decomposition efficiency of the source gas in the plasma increases, and the oxygen radicals increase , and the oxidation of the source gas proceeds. Therefore, the oxygen content in the insulating film 311b becomes higher than the stoichiometric ratio. However, when the substrate temperature is the film formation temperature of the insulating film 311b, since the binding force between silicon and oxygen is weak, a 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 having a part of the oxygen desorb due to heating can be formed. Also, an insulating film 311a is provided on the oxide semiconductor films 308a, 308b, and 308d. Therefore, in the formation process of the insulating film 311b, the insulating film 311a serves as a protective film for the oxide semiconductor films 308a, 308b, and 308d. As a result, acid ​​​​​​​​High power density while reducing damage to the compound semiconductor films 308a, 308b, and 308d. By using this high frequency power, the insulating film 311b can be formed.

[0240] In addition, in the film formation conditions of the insulating film 311b, a deposition gas containing silicon is mixed with an oxidizing gas. By increasing the flow rate of the gas, it is possible to reduce the number of defects in the insulating film 311b. Specifically, ESR measurements reveal that the g value is 2.001, which is due to the dangling bonds of silicon. The spin density of the signal that appears is 6×10 17 spins / cm 3 Less than 3 x 10 1 7 spins / cm 3 Less than or equal to 1.5×10 17 spins / cm 3 is less than or equal to It is possible to form an oxide insulating film with a small number of defects. As a result, the reliability of the transistor is improved. It can be improved.

[0241] Next, a heat treatment is performed. The temperature of the heat treatment is typically 150° C. or higher and lower than the substrate distortion point. The temperature is preferably 200° C. or higher and 450° C. or lower, and more preferably 300° C. or higher and 450° C. or lower. The temperature of the heat treatment is typically 300° C. or higher and 400° C. or lower, preferably 3 By keeping the temperature between 20℃ and 370℃, warping and shrinkage of the board can be prevented even in large boards. It is possible to reduce the number of defects and improve the yield.

[0242] The heat treatment can be performed using an electric furnace, an RTA device, or the like. In this case, the heat treatment can be performed at a temperature equal to or higher than the distortion point of the substrate for a short period of time. This can shorten the processing time.

[0243] The heat treatment may be carried out in an atmosphere of nitrogen, oxygen, ultra-dry air (air with a water content of 20 ppm or less, preferably 1 pp m or less, preferably 10 ppb or less), or a noble gas (argon, helium, etc.). It should be noted that it is preferable that the above nitrogen, oxygen, ultra-dry air, or noble gas does not contain hydrogen, water, etc. is preferably not included.

[0244] By this heat treatment, a part of the oxygen contained in the insulating film 311b is moved to the oxide semiconductor films 308a, 308b, 308d, and it is possible to reduce the oxygen deficiency contained in the oxide semiconductor films 308a, 308b, 308d. As a result, the amount of oxygen deficiency contained in the oxide semiconductor films 308a, 308b can be further reduced.

[0245] When the insulating films 311a and 311b contain water, hydrogen, etc., if an insulating film 313 having a function of blocking water, hydrogen, etc. is formed later and heat treatment is performed, the water, hydrogen, etc. contained in the insulating films 311a and 31 1b will move to the oxide semiconductor films 308a, 308b, 308d, and defects will occur in the oxide semiconductor films 308a, 308b, 308d. However, by this heating, it is possible to desorb water, hydrogen, etc. contained in the insulating films 311a and 311b, reduce the variation in the electrical characteristics of the transistor, and control the variation in the threshold voltage.

[0246] In addition, by forming the insulating film 311b on the insulating film 311a while heating, oxygen can be moved to the oxide semiconductor films 308a, 308b, 308d, and it is possible to reduce the oxygen deficiency contained in the oxide semiconductor films 308a, 308b 308d. Therefore, it is not necessary to perform the heat treatment. ​​​​​​

[0247] In addition, when forming the conductive films 310a, 310b, 310d, and 310e, the oxide semiconductor films 308a, 308b, and 308d are damaged by the etching of the conductive films. As a result, oxygen deficiency occurs on the back channel side (the side opposite to the surface facing the conductive films 304a and 304c that function as gate electrodes) of the oxide semiconductor films 308a and 308b. However, by applying an oxide insulating film containing more oxygen than the stoichiometric composition to the insulating film 311b, the oxygen deficiency generated on the back channel side can be repaired by heat treatment. Thereby, the defects contained in the oxide semiconductor films 308a and 308b can be reduced, and the reliability of the transistor can be improved. Note that the heat treatment may be performed after forming the opening 362 formed later. Next, by processing the insulating film 311 into a desired shape, the insulating film 312 and the opening 362 are formed. The formation of the insulating film 312 and the opening 362 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. 7(A)). Note that the opening 362 is formed so that the surface of the oxide semiconductor film 308d is exposed. As a method for forming the opening 362, for example, a dry etching method can be used. It is preferable to etch the insulating film 311 by the dry etching method. As a result, since the oxide semiconductor film 308d is exposed to plasma in the etching process, the oxide semiconductor film

[0248]

[0249]

[0250] It is possible to increase the oxygen deficiency of 308d. However, the method of forming the opening 362 and is not limited to this, and it may be a wet etching method, or a forming method combining a dry etching method and a wet etching method.

[0251] Next, an insulating film 313 is formed on the insulating film 312 and the oxide semiconductor film 308d (refer to Fig. 7(B ).).

[0252] As the insulating film 313, it is preferable to use a material that prevents impurities from the outside, such as oxygen, hydrogen, water, alkali metals, a lkali earth metals, etc., from diffusing into the oxide semiconductor film. Furthermore, it is preferably hydrogen-containing, and typically an inorganic insulating material containing nitrogen, such as a nitride insulating film, can be used. The insulating film 313 can be formed, for example, by a CVD method or a sputtering method.

[0253] When the insulating film 313 is formed by a plasma CVD method or a sputtering method, the oxide semiconductor film is exposed to plasma, and oxygen deficiency is generated in the oxide semiconductor film. Also, the insulating film 313 is a film formed of a material that prevents impurities from the outside, such as water, alkali metals, alkali earth metals, etc., from diffusing into the oxide semiconductor film, and furthermore contains hydrogen. Therefore, when the hydrogen in the insulating film 3 13 diffuses into the oxide semiconductor film 308d, in the oxide semiconductor film 308d hydrogen combines with oxygen, and carriers, electrons, are generated. Or, when hydrogen enters the oxygen deficiency contained in the oxide semiconductor film, carriers, electrons, are generated. As a result of these, the oxide semiconductor film 308d becomes highly conductive and becomes a metal oxide film 308c.

[0254] In addition, the above nitride insulating 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 400°C or lower, more preferably 300°C or higher and 400°C or lower. It is preferably formed by heating at such a temperature. 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 a phenomenon where the carrier concentration increases. Therefore, the temperature should be set so that such a phenomenon does not occur.

[0255] Next, a conductive film 315 is formed on the insulating film 313 (see Fig. 8(A)).

[0256] The conductive film 315 can be formed, for example, by using a sputtering method.

[0257] Next, the conductive film 316b is formed by processing the conductive film 315 into a desired shape. Note that the formation of the conductive film 316b can be performed by forming a mask by a fifth patterning in a desired region and etching the region not covered by the mask (see Fig. 8(B)). )

[0258] Next, an organic insulating film 317 is formed so as to cover the insulating film 313 and the conductive film 316b (see Fig. 8( C)). The organic insulating film 317 that functions as a planarizing film has an opening so that a part of the insulating film 313 is exposed.

[0259] As the organic insulating film 317, a photosensitive composition is applied onto the insulating film 313 and the conductive film 316b using a coating method such as a spin coating method or a dip coating method, and then the composition is exposed and developed by a photolithography process using a sixth photomask, and then heat treatment is performed. Note that when a non-photosensitive composition is applied onto the insulating film 313 and the conductive film 316b, the non-photosensitive composition Apply a resist on the composition and process the resist by a photolithography process using a sixth photomask to form a mask, and etch a non-photosensitive composition using the mask to form the organic insulating film 317.

[0260] Note that as the organic insulating film 317, it can be formed by using a wet method such as an inkjet method or a printing method to reduce the number of photomasks.

[0261] Next, using the organic insulating film 317 as a mask, etch a part of each of the insulating film 305, insulating film 306, insulating film 312, and insulating film 313 to form an opening 364a that exposes the conductive film 304b, an opening 364b that exposes the conductive film 310c, and an opening 364c that exposes the conductive film 310e (see Fig. 9(A)).

[0262] Next, form the conductive film 318 (see Fig. 9(B)).

[0263] As the conductive film 318, for example, it can be formed by using a sputtering method.

[0264] Next, process the conductive film 318 into a desired shape to form the conductive films 319 and 319a. Note that the formation of the conductive films 319 and 319a is performed by forming a mask by seventh patterning in a desired region and etching the region not covered by the mask (see Fig. 9(C)).

[0265] In the above steps, a pixel portion and a driving circuit portion having transistors can be formed on the substrate 302. Note that in the manufacturing process shown in this embodiment, the first to seventh patterning Namely, with seven photo masks, transistors and capacitor elements can be formed simultaneously. This is possible.

[0266] In this embodiment, hydrogen contained in the insulating film 313 is diffused into the oxide semiconductor film 308d to increase 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 increase the conductivity of the oxide semiconductor film 308d. As methods for adding hydrogen, boron, phosphorus, tin, antimony, noble gas elements, etc. to the oxide semiconductor film 308d, there are an ion doping method, an ion implantation method, etc. On the other hand, as a method for adding alkali metals, alkaline earth metals, etc. to the oxide semiconductor film 308d, there is a method of applying a solution containing the impurity to the oxide semiconductor film 308d. This is possible.

[0267] Next, the element portion provided on the substrate 342 provided opposite to the substrate 302 will be described below. Here, the element portion provided on the substrate 342 refers to the region sandwiched between the substrate 342 and the alignment film 352.

[0268] First, the substrate 342 is prepared. As the substrate 342, the materials shown for the substrate 302 can be used. Next, a light-shielding film 344 and a colored film 346 are formed on the substrate 342 (see Fig. 10(A)). ).

[0269] The light-shielding film 344 and the colored film 346 are formed at desired positions using various materials by printing, inkjet, etching methods using photolithography technology, etc.

[0270] ​​​​​​​​​​​ Next, an insulating film 348 is formed on the light-shielding film 344 and the colored film 346 (see Fig. 10(B)). .

[0271] As the insulating film 348, for example, an organic insulating film such as an acrylic resin, an epoxy resin, or a polyimide can be used. By forming the insulating film 348, for example, it is possible to suppress the diffusion of impurities contained in the colored film 346 to the liquid crystal layer 321 side. However , the insulating film 348 does not necessarily have to be provided, and a structure in which the insulating film 348 is not formed may also be acceptable.

[0272] Next, a conductive film 350 is formed on the insulating film 348 (see Fig. 10(C)). The conductive film 350 can use the materials shown for the conductive film 315.

[0273] The structure formed on the substrate 342 in the above steps can be formed.

[0274] Next, alignment films 320 and 352 are formed on the substrate 302 and on the substrate 342, more specifically, on the insulating film 317 , the conductive films 319 and 319a formed on the substrate 302, and on the conductive film 350 formed on the substrate 342, respectively . The alignment films 320 and 352 can be formed using the rubbing method , the photo-alignment method, or the like. After that, a liquid crystal layer 321 is formed between the substrate 302 and the substrate 342 . As a method for forming the liquid crystal layer 321, a dispenser method (dropping method ) or an injection method in which the liquid crystal is injected using capillary action after bonding the substrate 302 and the substrate 342 can be used.

[0275] The liquid crystal display device shown in Fig. 4 can be manufactured through the above steps.

[0276] ​Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. can be used in appropriate combination.

[0277] (Embodiment 3) In this embodiment, a liquid crystal display device including a transistor different from that in Embodiment 1 will be described. This will be explained with reference to FIG. 11 to FIG.

[0278] The liquid crystal display device shown in FIG. 11 has a dual gate structure in the driving circuit section indicated by AB. The semiconductor device is characterized by having a transistor 102a.

[0279] The transistor 102a provided in the driving circuit section has a gate electrode provided on a substrate 302. and the insulating films 305 and 306 functioning as the gate insulating film 51. 6, an oxide semiconductor film 308a formed on the insulating film 306, and and conductive films 310a and 310b which function as a source electrode and a drain electrode, In addition, an inorganic insulating film 53 is formed over the oxide semiconductor film 308a and the conductive films 310a and 310b. A conductive film 316d that functions as a gate electrode is formed on the inorganic insulating film 53. The conductive film 316d functioning as a gate electrode is formed on the gate insulating film 51 and the inorganic insulating film 53. In the opening (not shown), a conductive film 304a which functions as a gate electrode is formed. That is, the conductive film 304a and the conductive film 316d have the same potential.

[0280] Therefore, by applying the same voltage to each gate electrode of the transistor 102a, Reduction of characteristic variations, suppression of degradation during GBT stress testing, and performance at different drain voltages In addition, the oxide semiconductor film 308a can suppress a change in a rise voltage of an on-state current. In this case, since the region through which carriers flow becomes larger in the film thickness direction, the movement of carriers increases. As a result, the on-current of the transistor 102a increases, and the field-effect mobility becomes high. Typically, the field-effect mobility is 20 cm 2 / V·s or more.

[0281] At the end of the oxide semiconductor film processed by etching or the like, defects are formed due to damage in the processing, and it is contaminated by impurity adhesion or the like. Therefore, when a stress such as an electric field is applied, it is easily activated and tends to become n-type (low resistance). Therefore, at the end of the oxide semiconductor film 308a that overlaps with the conductive film 304a that functions as a gate electrode, it tends to become n-type. When the n-type end portion is provided between the conductive films 310a and 310b that function as source electrodes and drain electrodes, the n-type region becomes a path for carriers, and a parasitic channel is formed. However, in the channel width direction, when the conductive film 316d that functions as a gate electrode is provided, due to the influence of the electric field of the conductive film 316d that functions as a gate electrode, the generation of parasitic channels at the side surface of the oxide semiconductor film 308a, or at the end portion including the side surface and its vicinity is suppressed. As a result, a transistor with excellent electrical characteristics is obtained, in which the increase in drain current at the threshold voltage is steep.

[0282] Note that the conductive film 316d that functions as a gate electrode can be appropriately formed of the same material as the conductive film 316b shown in Embodiment 2.

[0283] <Modification 1> The liquid crystal display device shown in FIG. 11 of Embodiment 3 uses, as a transistor in the drive circuit section, a dual Although it is manufactured using a transistor with a lug gate structure, as shown in FIG. 12, between A and B The drive circuit section shown has a transistor 102a with a dual gate structure, and between C and D A transistor 103a with a dual gate structure may be used for the pixel section shown.

[0284] The transistor 103a includes a conductive film 3 04c that functions as a gate electrode provided on the substrate 302, insulating films 305 and 306 that function as a gate insulating film, and An oxide semiconductor film 308b formed on the insulating film 306, and conductive films 310d and 310e that are in contact with the oxide semiconductor film 308b and function as source and drain electrodes. Further, an inorganic insulating film 53 is formed on the oxide semiconductor film 308b and the conductive films 310d and 310e, and a conductive film 316e that functions as a gate electrode is formed on the inorganic insulating film 53. The conductive film 316e that functions as a gate electrode is connected to the conductive film 304c that functions as a gate electrode at an opening (not shown) provided in the gate insulating film 51 and the inorganic insulating film 53. That is, the conductive films 304c and 316e are at the same potential.

[0285] By providing a transistor with a dual gate structure that has high reliability, a large on-current, and a high field-effect mobility in the pixel section together with the drive circuit section, a liquid crystal display device with excellent display quality can be manufactured.

[0286] <Modification 2> In the liquid crystal display device shown in Embodiment 2 or Embodiment 3, as shown in FIG. 13, in a region overlapping with the transistor 102a provided in the drive circuit section and on the organic insulating film 31 7, a conductive film 319b formed simultaneously with the conductive film 319 may be provided. The conductive film 319​​​​ b can be set to any potential such as a common potential or a ground potential. By providing a conductive film 319b that overlaps with the transistor 102a having a dual gate structure, the electric field generated by the voltage applied to the conductive film 316d that functions as the gate electrode of the transistor 102a can be shielded by the conductive film 319b. As a result, the alignment defect of the liquid crystal layer 321 due to the electric field can be prevented.

[0287] <Modification 3> In Embodiment 2 or Embodiment 3, although a liquid crystal display device having an organic insulating film 317 in the drive circuit section and the pixel section has been described, as shown in FIG. 14, an organic insulating film 317 a may be provided only in the pixel section.

[0288] In the liquid crystal display device shown in FIG. 14, after forming the insulating film 313 as shown in FIG. 7(B), a mask is formed by patterning, and the insulating films 305, 30 6, 312, and 313 are etched respectively to form openings. Next, after forming the conductive film 315 shown in FIG. 8(A), simultaneously with forming the conductive film 316b shown in FIG. 8(B), a conductive film 316a connecting the conductive film 304b and the conductive film 310c is formed. After that, an organic insulating film 317a and a conductive film 319 are formed.

[0289] In addition, as shown in FIG. 15, when the organic insulating film 317a is not provided in the drive circuit section, on the conductive film 316d that functions as the gate electrode of the transistor 102a having a dual gate structure, a conductive film 319c formed simultaneously with the conductive film 319 may be provided. <Modification 4>

[0290] ​​​​​In Embodiment 2 and Embodiment 3, although a liquid crystal element is used as an example of the display element, various display elements can be used. As an example, an example of the case using an organic EL element is shown in FIGS. 23, 24, 25, and 26. A display device having an organic EL element has an organic resin film 371 such as an acrylic resin, a polyimide, or an epoxy resin, an EL layer 373 provided on the organic resin film, and a common electrode 375 provided on the EL layer. Further, an organic EL element is constituted by a conductive film 319, an EL layer 373, and a common electrode 375. However, various display elements can be used. As an example, an example of the case using an organic EL element is shown in FIGS. 23, 24, 25, and 26. A display device having an organic EL element has an organic resin film 371 such as an acrylic resin, a polyimide, or an epoxy resin, an EL layer 373 provided on the organic resin film, and a common electrode 375 provided on the EL layer. A display device having an organic EL element has an organic resin film 371 such as an acrylic resin, a polyimide, or an epoxy resin, an EL layer 373 provided on the organic resin film, and a common electrode 375 provided on the EL layer. An EL layer 373 is provided on the organic resin film, and a common electrode 375 is provided on the EL layer. Also, an organic EL element is constituted by a conductive film 319, an EL layer 373, and a common electrode 375. An EL layer 373 is provided on the organic resin film, and a common electrode 375 is provided on the EL layer. Also, an organic EL element is constituted by a conductive film 319, an EL layer 373, and a common electrode 375.

[0291] Note that the configurations, methods, and the like described in this embodiment can be used in appropriate combination with the configurations, methods, and the like described in other embodiments. Note that the configurations, methods, and the like described in this embodiment can be used in appropriate combination with the configurations, methods, and the like described in other embodiments.

[0292] (Embodiment 4) In the transistors 102, 102a, 103, and 103a shown in Embodiment 2 and Embodiment 3, a stacked structure of an oxide semiconductor film can be formed as necessary. Here, the transistor 103 will be described. In the transistors 102, 102a, 103, and 103a shown in Embodiment 2 and Embodiment 3, a stacked structure of an oxide semiconductor film can be formed as necessary. Here, the transistor 103 will be described. In the transistors 102, 102a, 103, and 103a shown in Embodiment 2 and Embodiment 3, a stacked structure of an oxide semiconductor film can be formed as necessary. Here, the transistor 103 will be described.

[0293] In the transistor shown in FIG. 16, a multilayer film 336 including an oxide semiconductor film is formed between an insulating film 306 and conductive films 310d and 310e. In the transistor shown in FIG. 16, a multilayer film 336 including an oxide semiconductor film is formed between an insulating film 306 and conductive films 310d and 310e.

[0294] The multilayer film 336 has an oxide semiconductor film 336a and an oxide semiconductor film 336b. That is, the multilayer film 336 has a two-layer structure. Also, a part of the oxide semiconductor film 336a functions as a channel region. Further, an insulating film 312a is formed so as to be in contact with the multilayer film 336, and an oxide semiconductor film 336b is formed so as to be in contact with the insulating film 312a. That is, an oxide semiconductor film 336b is formed so as to be in contact with the insulating film 312a. The multilayer film 336 has an oxide semiconductor film 336a and an oxide semiconductor film 336b. That is, the multilayer film 336 has a two-layer structure. Also, a part of the oxide semiconductor film 336a functions as a channel region. Further, an insulating film 312a is formed so as to be in contact with the multilayer film 336, and an oxide semiconductor film 336b is formed so as to be in contact with the insulating film 312a. That is, an oxide semiconductor film 336b is formed so as to be in contact with the insulating film 312a. Further, an insulating film 312a is formed so as to be in contact with the multilayer film 336, and an oxide semiconductor film 336b is formed so as to be in contact with the insulating film 312a. That is, an oxide semiconductor film 336b is formed so as to be in contact with the insulating film 312a. An oxide semiconductor film 336b is provided between the semiconductor film 336a and the insulating film 312a. .

[0295] The oxide semiconductor film 336b is composed of one or more of the elements constituting the oxide semiconductor film 336a. Since the oxide semiconductor film 336b is composed of one or more of the elements constituting the oxide semiconductor film 336a, interface scattering is unlikely to occur at the interface between the oxide semiconductor film 336a and the oxide semiconductor film 336b. Therefore, carrier movement is not inhibited at the interface. As a result, the field-effect mobility of the transistor is increased.

[0296] Typically, the oxide semiconductor film 336b is In-Ga oxide, In-Zn oxide, In- M-Zn oxide (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf ), and the energy of the lower end of the conduction band of the oxide semiconductor film 336b is closer to the vacuum level than that of the oxide semiconductor film 336a. Typically, the difference between the energy of the lower end of the conduction band of the oxide semiconductor film 336b and the energy of the lower end of the conduction band of the oxide semiconductor film 336a 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 difference between the electron affinity of the oxide semiconductor film 336b and the electron affinity of the oxide semiconductor film 336a 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.

[0297] The oxide semiconductor film 336b preferably contains In because the carrier mobility (electron mobility) is increased.

[0298] As the oxide semiconductor film 336b, having Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf at an atomic ratio higher than that of In may have the following effects. ( 1) Increase the energy gap of the oxide semiconductor film 336b. (2) The oxide semiconductor film 336b to reduce the electron affinity. (3) Shield impurities from the outside. (4) Oxide Compared with the semiconductor film 336a, the insulating property becomes higher. (5) Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf is a metal element with a strong bonding force with oxygen. Therefore, Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf having an atomic ratio higher than that of In makes it difficult for oxygen deficiency to occur.

[0299] When the oxide semiconductor film 336b is an In-M-Zn oxide, the atomic ratio of In and M is less than 50 atomic% of In and 50 atomic% or more of M when the sum of In and M is 100 atomic%. More preferably, In is less than 25 atomic% and M is 7 5 atomic% or more.

[0300] Also, when the oxide semiconductor film 336a and the oxide semiconductor film 336b are In-M-Zn oxides ( M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf), compared with the oxide semiconductor film 336a, the atomic ratio of M (Al, Ti, Ga , Y, Zr, La, Ce, Nd, Sn or Hf) contained in the oxide semiconductor film 336b is large. Typically, compared with the above atoms contained in the oxide semiconductor film 336a, it is 1.5 times or more, preferably 2 times or more above, and more preferably 3 times or more higher atomic ratio.

[0301] In addition, when the oxide semiconductor film 336a and the oxide semiconductor film 336b are In-M-Zn oxide ( M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf), the oxide semiconductor film 336b is In:M:Zn = x 1 :y 1 :z 1 [atomic ratio], and the oxide semiconductor film 3 36a is In:M:Zn = x 2 :y 2 :z 2 [atomic ratio], then y 1 / x 1 is greater than y 2 / x 2 Preferably, y 1 / x 1 is at least 1.5 times greater than y 2 / x 2 . More preferably, y / x 1 is at least twice as large as y 1 / x 2 / x 2 . Even more preferably, y 1 / x 1 is at least three times as large as y 2 / x 2 . At this time, in the oxide semiconductor film 336b, when y 1 is equal to or greater than x 1 , stable electrical characteristics can be imparted to the transistor using the oxide semiconductor film, which is preferable. However, when y exceeds three times x 1 / 1 , the field-effect mobility of the transistor using the oxide semiconductor film decreases. Therefore, it is preferable that y 1 is less than three times x 1 .

[0302] For example, when the oxide semiconductor film 336a is In:Ga:Zn = 1:1:1, In:Ga:Z Use an In-Ga-Zn oxide with an atomic ratio of n = 1:1:1.2, or 3:1:2 is possible. Further, as the oxide semiconductor film 336b, In:Ga:Zn = 1:3:n (n is an integer of 2 or more and 8 or less), 1:6:m (m is an integer of 2 or more and 10 or less), or 1:9:6 of the atomic ratio of In-Ga-Zn oxide can be used. Note that the atomic ratios of the oxide semiconductor film 336 a and the oxide semiconductor film 336b each include a variation of plus or minus 20% of the above atomic ratio as an error. In the oxide semiconductor film 336a, it is preferable that the ratio of Zn is equal to or greater than Ga because CAAC-OS is likely to be formed.

[0303] The oxide semiconductor film 336b also functions as a damage relaxation film for the oxide semiconductor film 336a when forming the insulating film 312b formed later.

[0304] The thickness of the oxide semiconductor film 336b is 3 nm or more and 100 nm or less, preferably 3 nm or more and 5 0 nm or less.

[0305] Further, the oxide semiconductor film 336b may have, like the oxide semiconductor film 336a, for example, a non-single crystal structure. The non-single crystal structure includes, for example, CAAC-OS (C Axis Aligned Crystalline Oxide Semiconductor) described later, a polycrystalline structure, a microcrystalline structure described later, or an amorphous structure. gned Crystalline Oxide Semiconductor), a polycrystalline structure, a microcrystalline structure described later, or an amorphous structure.

[0306] Note that the oxide semiconductor film 336a and the oxide semiconductor film 336b may each be a mixed film having two or more of an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CAAC-OS region, and a single crystal structure region. The mixed film includes, for example, an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CAAC-OS region, and a single crystal structure region. The mixed film includes, for example, an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CAAC-OS region, and a single crystal structure region. The mixed film includes, for example, an amorphous structure region, a microcrystalline ​​​Any two of a structural region, a polycrystalline structure region, a CAAC-OS region, and a single crystal structure region There may be a case of a single-layer structure having two or more such regions. Further, the mixed film may have, for example, a laminated structure of any two or more regions of an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CAAC-OS region, and a single crystal structure region.

[0307] Here, an oxide semiconductor film 336b is provided between the oxide semiconductor film 336a and the insulating film 312a. Therefore, even if trap levels are formed due to impurities and defects between the oxide semiconductor film 336b and the insulating film 312a, there is a gap between the trap levels and the oxide semiconductor film 336a. As a result, electrons flowing through the oxide semiconductor film 336a are less likely to be trapped by the trap levels, and it is possible to increase the on-current of the transistor. At the same time, the field-effect mobility can be increased. Further, when electrons are trapped by the trap levels, the electrons become negative fixed charges. As a result, the threshold voltage of the transistor fluctuates. However, since there is a gap between the oxide semiconductor film 336a and the trap levels, it is possible to reduce the trapping of electrons at the trap levels and reduce the fluctuation of the threshold voltage.

[0308] Further, since the oxide semiconductor film 336b can shield impurities from the outside, it is possible to reduce the amount of impurities moving from the outside to the oxide semiconductor film 336a. Also, the oxide semiconductor film 336b is less likely to form oxygen deficiencies. For these reasons, it is possible to reduce the impurity concentration and the amount of oxygen deficiency in the oxide semiconductor film 336a.

[0309] ​​​​​​​​​​​​​​Note that the oxide semiconductor film 336a and the oxide semiconductor film 336b are simply stacked on top of each other, so there is no continuous junction (here, in particular, the energy at the lower end of the conduction band changes continuously between the films to form a structure). That is, a stacked structure is adopted in which there are no impurities that form defect energy levels such as trap centers or recombination centers at the interface of each film. Suppose that there are impurities mixed between the stacked oxide semiconductor film 336a and the oxide semiconductor film 336b. In that case, the continuity of the energy band is lost, carriers are trapped at the interface, and either recombine and disappear.

[0310] To form a continuous junction, it is necessary to continuously stack each film without exposing it to the atmosphere using a multi-chamber film-forming apparatus equipped with a load lock chamber (sputtering apparatus). Each chamber in the sputtering apparatus should be evacuated to a high vacuum (to about 5×10 −4 Pa to 1×10 −6 Pa) using an adsorption-type vacuum exhaust pump such as a cryopump to remove impurities such as water that can become impurities in the oxide semiconductor film as much as possible. Or, it is preferable to combine a turbo molecular pump and a cold trap to prevent gas, especially gas containing carbon or hydrogen, from flowing back into the chamber from the exhaust system. -7 -4

[0311] Note that in FIG. 16, the multilayer film 336 has a two-layer structure of the oxide semiconductor film 336a and the oxide semiconductor film 33 6b. However, a three-layer structure may be adopted in which a film similar to the oxide semiconductor film 336b is further provided between the insulating film 306 and the oxide semiconductor film 336a. In this case, the insulating film 306 and The thickness of the oxide film provided between the oxide semiconductor film 336a is preferably smaller than that of the oxide semiconductor film 336a. It is preferably 1 nm or more and 5 nm or less, and more preferably 1 nm or more and 3 nm or less. By setting the thickness of the oxide film in this range, it is possible to reduce the variation in the threshold voltage of the transistor. .

[0312] Note that the configurations and methods described in this embodiment can be used in appropriate combination with those described in other embodiments.

[0313] (Embodiment 5) In this embodiment, one aspect applicable to the oxide semiconductor film in the transistor included in the display device described in the above embodiment will be described.

[0314] The oxide semiconductor film may be composed of one or more of an oxide semiconductor having a single crystal structure (hereinafter referred to as a single crystal oxide semiconductor), an oxide semiconductor having a polycrystalline structure (hereinafter referred to as a polycrystalline oxide semiconductor), an oxide semiconductor having a microcrystalline structure (hereinafter referred to as a microcrystalline oxide semiconductor), and an oxide semiconductor having an amorphous structure (hereinafter referred to as an amorphous oxide semiconductor). Further, the oxide semiconductor film may be composed of a CAAC-OS film. Further, the oxide semiconductor film may be composed of an amorphous oxide semiconductor and an oxide semiconductor having crystal grains. Hereinafter, as representative examples, CAAC-OS and microcrystalline oxide semiconductors will be described.

[0315] First, the CAAC-OS film will be described.

[0316] The CAAC-OS film is one of the oxide semiconductor films having a plurality of crystal parts oriented in the c-axis direction.

[0317] When the CAAC-OS film is observed by a transmission electron microscope (TEM), the boundaries between distinct crystal parts, that is, grain boundaries (also referred to as grain boundaries), cannot be confirmed. Therefore, it can be said that in the CAAC-OS film, a decrease in electron mobility due to grain boundaries is less likely to occur. When the CAAC-OS film is observed by TEM in a direction roughly parallel to the sample surface (cross-sectional TEM observation), it can be confirmed that in the crystal part, metal atoms are arranged in layers. Each layer of metal atoms has a shape that reflects the unevenness of the surface (also referred to as the formed surface) or the upper surface of the CAAC-OS film, and is arranged parallel to the formed surface or the upper surface of the CAAC-OS film. On the other hand, when the CAAC-OS film is observed by TEM in a direction roughly 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. Figure 17(a) is a cross-sectional TEM image of the CAAC-OS film. Figure 17(b) is a magnified cross-sectional TEM image of Figure 17(a), and the atomic arrangement is emphasized for easy understanding.

[0318] Figure 17(c) is a local Fourier transform image of the region (diameter approximately 4 nm) enclosed by a circle between A-O-A' in Figure 17(a). From Figure 17(c), c-axis orientation can be confirmed in each region. Also, since the direction of the c-axis is different between the A-O and O-A' intervals, different grains

[0319]

[0320]

[0321] ​​​​​​​​​​​​​It is suggested that it is In. Also, between A and O, it can be seen that the angle of the c-axis changes continuously little by little, such as 14.3°, 16.6 °, 26.4°. Similarly, between O and A', it can be seen that the angle of the c-axis changes continuously little by little as -18.3°, -17.6°, -15.9° .

[0322] When electron diffraction is performed on the CAAC-OS film, spots (bright spots) indicating orientation are observed . For example, when electron diffraction (also called nano-beam electron diffraction) using an electron beam of, for example, 1 nm or more and 30 nm or less is performed on the upper surface of the CAAC-OS film, spots are observed (see Fig. 18(A)).

[0323] From cross-sectional TEM observation and planar TEM observation, it can be seen that the crystal part of the CAAC-OS film has orientation .

[0324] Most of the crystal parts included in the CAAC-OS film are sized to fit 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 they are sized to fit within a cube with a side length of less than 10 nm , less than 5 nm or less than 3 nm. However, when a plurality of crystal parts included in the CAAC-OS film are connected, a single large crystal region may be formed . For example, in a planar TEM image, a crystal region of 2500 nm 2 or more, 5 μm 2 or more or 1000 μm 2 or more may be observed

[0325] When structural analysis is performed on the CAAC-OS film using an X-ray diffraction (XRD: X-Ray Diffraction) device, for example, a CAAC-OS film having a crystal of InGaZnO 4 ​​​​ In the out-of-plane method analysis, a peak may appear near a diffraction angle (2θ) of 31°. This peak is attributed to the (009) plane of the InGaZnO 4 crystal, indicating that the crystals of the CAAC-OS film have c-axis orientation, and the c-axis is oriented in a direction approximately perpendicular to the surface to be formed or the upper surface. It can be confirmed.

[0326] On the other hand, in the in-plane method analysis where X-rays are incident on the CAAC-OS film from a direction approximately perpendicular to the c-axis, a peak may appear near 2θ of 56°. This peak is attributed to the (110) plane of the InGaZnO crystal. For a single-crystal oxide 4 semiconductor film of InGaZnO, if the analysis (φ scan) is performed while rotating the sample with 2θ fixed near 56° and 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, for the CAAC-OS film, no distinct peak appears even when φ scan is performed with 2θ fixed near 5 4 6°. From the above, in the CAAC-OS film, the orientations of the a-axis and b-axis are irregular among 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 surface to be formed or the upper surface. Therefore, each layer of the metal atoms arranged in a layered manner confirmed by the cross-sectional TEM observation mentioned above is a plane parallel to the ab plane of the crystal.

[0327] From the above, in the CAAC-OS film, although the orientations of the a-axis and b-axis are irregular among different crystal parts, it has c-axis orientation, and the c-axis is oriented in a direction parallel to the normal vector of the surface to be formed or the upper surface. It can be understood. Therefore, as confirmed by the above-mentioned cross-sectional TEM observation, each layer of the metal atoms arranged in a layered manner is a plane parallel to the ab plane of the crystal.

[0328] 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 the surface to be formed of the CAAC-OS film or It is oriented in a direction parallel to the normal vector of the upper surface. 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 parallel to the formed surface or the normal vector of the upper surface of the CAAC-OS film.

[0329] Also, in the CAAC-OS film, the distribution of the c-axis oriented crystal portions may not be uniform. For example, when the crystal portions of the CAAC-OS film are formed by crystal growth from near the upper surface of the CAAC-OS film the region near the upper surface may have a higher ratio of c-axis oriented crystal portions than the region near the formed surface. Also, in the CAAC-OS film doped with impurities, the region where the impurities are doped is altered, and regions with different ratios of partially c-axis oriented crystal portions may be formed. This may also occur.

[0330] Note that in the out-of-plane analysis of the CAAC-OS film having InGaZnO 4 crystals, in addition to the peak at around 2θ = 31°, a peak may also appear at around 2θ = 36°. The peak at around 2θ = 36° indicates that a part of the CAAC-OS film contains crystals without 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°.

[0331] 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 that 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 and reduce the crystallinity. is a cause. In addition, heavy metals such as iron and nickel, argon, carbon dioxide, etc. have a large atomic radius (or molecular radius), so when they are contained inside the oxide semiconductor film, they become a factor that disrupts the atomic arrangement of the oxide semiconductor film and reduces the crystallinity. Note that impurities contained in the oxide semiconductor film may serve as carrier traps or carrier generation sources.

[0332] In addition, the CAAC-OS film is an oxide semiconductor film with a low density of defect levels. For example, oxygen deficiency in the oxide semiconductor film may serve as a carrier trap or may become a carrier generation source by capturing hydrogen.

[0333] A low impurity concentration and a low density of defect levels (low oxygen deficiency) are called high-purity intrinsic or substantially high-purity intrinsic. An oxide semiconductor film that is high-purity intrinsic or substantially high-purity intrinsic has few carrier generation sources, so the carrier density can be lowered. Therefore, a transistor using such an oxide semiconductor film is less likely to have an electrical characteristic (also called normally-off) in which the threshold voltage becomes negative. In addition, an oxide semiconductor film that is high-purity intrinsic or substantially high-purity intrinsic has few carrier traps. Therefore, a transistor using such an oxide semiconductor film has small fluctuations in electrical characteristics and becomes a highly reliable transistor. Note that the charge trapped in the carrier trap of the oxide semiconductor film may take a long time to be released and may behave like a fixed charge. Therefore, a transistor using an oxide semiconductor film with a high impurity concentration and a high density of defect levels may have unstable electrical characteristics.

[0334] In addition, the transistors using the CAAC-OS film have small variations in electrical characteristics due to irradiation with visible light or ultraviolet light.

[0335] Next, the microcrystalline oxide semiconductor film will be described.

[0336] In the observation image by TEM, the crystal part may not be clearly confirmed in the microcrystalline oxide semiconductor film. The crystal part contained in the microcrystalline oxide semiconductor film often has a size of 1 nm or more and 100 nm or less, or 1 nm or more and 10 nm or less. In particular, nanocrystals (nc: nanocrystalline) with a size 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. In addition, in the observation image by TEM, for example, the grain boundaries of the nc-OS film may not be clearly confirmed.

[0337] 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). In addition, the nc-OS film has no regularity in the crystal orientation between different crystal parts. Therefore, no orientation is observed in the whole film. Accordingly, depending on the analysis method, there are cases where the nc-OS film cannot be distinguished from the amorphous oxide semiconductor film. For example, when performing structural analysis on the nc-OS film using an XRD apparatus that uses X-rays with a diameter larger than that of the crystal part, no peak indicating the crystal plane is detected in the analysis by the out-of-plane method. In addition, for the nc-OS film, electron diffraction (also called limited-field electron diffraction) using an electron beam with a probe diameter larger than that of the crystal part (for example, 50 nm or more) is performed. and a diffraction pattern such as a halo pattern is observed. On the other hand, for the nc-OS film, when nano-beam electron diffraction is performed using an electron beam with a probe diameter close to or smaller than the size of the crystal part, spots are observed. When performing nano-beam electron diffraction using an electron beam with a probe diameter close to or smaller than the size of the crystal part. When performing nano-beam electron diffraction on the nc-OS film, spots are observed. When performing nano-beam electron diffraction on the nc-OS film, there are cases where regions with high brightness are observed in a circular (ring-like) shape. When performing nano-beam electron diffraction on the nc-OS film, there are cases where a plurality of spots are observed within the ring-shaped region (see Fig. 18(B)). (See Fig. 18(B).)

[0338] The nc-OS film is an oxide semiconductor film with higher regularity than the amorphous oxide semiconductor film. Therefore, the nc-OS film has a lower density of defect energy levels than the amorphous oxide semiconductor film. However, in the nc-OS film, there is no regularity 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. Therefore, the nc-OS film has a lower density of defect energy levels than the amorphous oxide semiconductor film. However, in the nc-OS film, there is no regularity 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.

[0339] Note that the oxide semiconductor film may be a laminated film having two or more of, for example, an amorphous oxide semiconductor film, a microcrystalline oxide semiconductor film, and a CAAC-OS film. When the oxide semiconductor film has a plurality of structures, structural analysis may be possible by using nano-beam electron diffraction.

[0340] When the oxide semiconductor film has a plurality of structures, structural analysis may be possible by using nano-beam electron diffraction. When the oxide semiconductor film has a plurality of structures, structural analysis may be possible by using nano-beam electron diffraction.

[0341] Fig. 18(C) shows a transmission electron diffraction measurement apparatus having an electron gun chamber 70, an optical system 72 below the electron gun chamber 70, a sample chamber 74 below the optical system 72, an optical system 76 below the sample chamber 74, an observation chamber 80 below the optical system 76, a camera 78 installed in the observation chamber 80, and a film chamber 82 below the observation chamber 80. The camera 78 is installed facing the inside of the observation chamber 80. Note that the film Fig. 18(C) shows a transmission electron diffraction measurement apparatus having an electron gun chamber 70, an optical system 72 below the electron gun chamber 70, a sample chamber 74 below the optical system 72, an optical system 76 below the sample chamber 74, an observation chamber 80 below the optical system 76, a camera 78 installed in the observation chamber 80, and a film chamber 82 below the observation chamber 80. Fig. 18(C) shows a transmission electron diffraction measurement apparatus having an electron gun chamber 70, an optical system 72 below the electron gun chamber 70, a sample chamber 74 below the optical system 72, an optical system 76 below the sample chamber 74, an observation chamber 80 below the optical system 76, a camera 78 installed in the observation chamber 80, and a film chamber 82 below the observation chamber 80. The camera 78 is installed facing the inside of the observation chamber 80. Fig. 18(C) shows a transmission electron diffraction measurement apparatus having an electron gun chamber 70, an optical system 72 below the electron gun chamber 70, a sample chamber 74 below the optical system 72, an optical system 76 below the sample chamber 74, an observation chamber 80 below the optical system 76, a camera 78 installed in the observation chamber 80, and a film chamber 82 below the observation chamber 80. The camera 78 is installed facing the inside of the observation chamber 80. Note that the film It is not necessary to have the film chamber 82.

[0342] Further, Fig. 18(D) shows the internal structure of the transmission electron diffraction measurement apparatus shown in Fig. 18(C). Inside the transmission electron diffraction measurement apparatus, electrons emitted from an electron gun installed in the electron gun chamber 70 are irradiated onto a substance 88 arranged in the sample chamber 74 via an optical system 72. The electrons that have passed through the substance 88 enter a fluorescent plate 92 installed inside the observation chamber 80 via an optical system 76. In the fluorescent plate 92, a pattern corresponding to the intensity of the incident electrons appears, and thus the transmission electron diffraction pattern can be measured.

[0343] The camera 78 is installed facing the fluorescent plate 92 and can photograph the pattern that appears on the fluorescent plate 92. The angle formed by the straight line passing through the center of the lens of the camera 78 and the center of the fluorescent plate 92 and the upper surface of the fluorescent plate 92 is, for example, 15° or more and 80° or less, 30° or more and 7 5° or less, or 45° or more and 70° or less. The smaller the angle, the greater the distortion of the transmission electron diffraction pattern photographed by the camera 78. However, if the angle is known in advance , it is also possible to correct the distortion of the obtained transmission electron diffraction pattern. Note that the camera 78 may be installed in the film chamber 82. For example, the camera 78 may be installed in the film chamber 82 so as to face the incident direction of the electrons 84. In this case, a transmission electron diffraction pattern with less distortion can be photographed from the back surface of the fluorescent plate 9 2.

[0344] In the sample chamber 74, a holder for fixing the substance 88 as the sample is installed. The holder has a structure that allows electrons passing through the substance 88 to pass through. The holder is, for example, a substance ​It may have a function of moving 88 along the X-axis, Y-axis, Z-axis, etc. The moving function of the holder is , for example, in the range of 1 nm or more and 10 nm or less, 5 nm or more and 50 nm or less, 10 nm or more and 100 nm or less, 50 nm or more and 500 nm or less, 100 nm or more and 1 μm or less, etc., and it may have an accuracy of moving. These ranges may be set to an optimal range according to the structure of the substance 88. .

[0345] Next, a method for measuring the transmission electron diffraction pattern of a substance using the above-described transmission electron diffraction measurement apparatus will be described. .

[0346] For example, as shown in Fig. 18(D), by changing (scanning) the irradiation position of the electron 84 which is a nano-beam in the substance, it is possible to confirm how the structure of the substance changes. At this time, if the substance 88 is a CAAC-OS film, a diffraction pattern as shown in Fig. 18(A) will be observed. Or, if the substance 88 is an nc-OS film, a diffraction pattern as shown in Fig. 18(B) will be observed.

[0347] By the way, even if the substance 88 is a CAAC-OS film, a diffraction pattern similar to that of an nc-OS film or the like may be partially observed. Therefore, the quality of the CAAC-OS film may be represented by the ratio of the area where the diffraction pattern of the CAAC-OS film in a certain range is observed (also referred to as the CAAC conversion rate). For example, if it is a high-quality CAAC-OS film, the CAAC conversion rate is 50% or more, preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. Note that the ratio of the area where a diffraction pattern different from that of the CAAC-OS film is observed is denoted as the non-CAAC conversion rate.

[0348] As an example, for each sample having a CAAC-OS film immediately after film formation (denoted as as-sputtered), or after heat treatment at 450 °C in an oxygen-containing atmosphere a transmission electron diffraction pattern was obtained while scanning the upper surface. Here, the diffraction pattern was observed while scanning at a speed of 5 nm / second for 60 seconds, and the observed diffraction pattern was converted into still images every 0.5 seconds to derive the CAAC conversion rate. Note that as the electron beam, a nano-beam with a probe diameter of 1 nm was used. The same measurement was performed on 6 samples. And for the calculation of the CAAC conversion rate, the average value of the 6 samples was used. The CAAC conversion rate for each sample is shown in Fig. 19(A). The CAAC conversion rate of the CAAC-OS film immediately after film formation was 75.7% (the non-CAAC conversion rate was 24.3%). Also, the CAAC conversion rate of the CAAC-OS film after heat treatment at 450 °C was 85.3% (the non-CAAC conversion rate was 14.7%). It can be seen that the CAAC conversion rate after heat treatment at 450 °C is higher than that immediately after film formation. That is, it can be seen that by heat treatment at a high temperature (for example, 400 °C or higher), the non-CAAC conversion rate becomes low (the CAAC conversion rate becomes high). Also, it can be seen that a CAAC-OS film having a high CAAC conversion rate can be obtained even in heat treatment below 500 °C. Here, most of the diffraction patterns different from the CAAC-OS film were the same as the diffraction pattern of the nc-OS film. Also, in the measurement region, an amorphous oxide semiconductor film could not be confirmed. Therefore, it is suggested that by heat treatment, regions having the same structure as the nc-OS film are rearranged under the influence of the structure of adjacent regions and become CAAC.

[0349]

[0350] ​​​​​​​​​​​​​

[0351] FIGS. 19(B) and 19(C) are plan TEM images of the CAAC-O S film immediately after film formation and after heat treatment at 450°C. By comparing FIG. 19(B) and FIG. 19(C), it can be seen that the CAAC-OS film after heat treatment at 45 0°C has a more homogeneous film quality. That is, it can be seen that the film quality of the CAAC-OS film is improved by heat treatment at a high temperature.

[0352] If such a measurement method is used, structural analysis of an oxide semiconductor film having a plurality of structures may be possible.

[0353] Note that the configurations and methods shown in this embodiment can be used in appropriate combination with the configurations and methods shown in other embodiments.

[0354] (Embodiment 6) As described in Embodiment 2, a transistor using an oxide semiconductor film can control the current value (off-current value) in the off state to be low. Therefore, the holding time of an electrical signal such as an image signal can be lengthened, and the writing interval can also be set long.

[0355] The liquid crystal display device of this embodiment can be a liquid crystal display device that performs display in at least two driving methods (modes) by applying a transistor with a low off-current value. The first driving mode is the driving method of a conventional liquid crystal display device, and is a driving method in which data is sequentially rewritten every frame. The second driving mode is a driving method in which, after executing the data writing process, the data rewriting is stopped. That is, it is a driving mode with a reduced refresh rate.

[0356] ​​​​​​​Video display is performed in the first driving mode. Since there is no change in the image data for each frame when displaying a still image, it is not necessary to rewrite the data for each frame. Therefore, when displaying a still image, operating in the second driving mode can eliminate screen flicker and at the same time, reduce power consumption.

[0357] In addition, the liquid crystal element applied to the liquid crystal display device of this embodiment has a large-capacity element with a large area, and the amount of charge accumulated in the capacitive element is large. Therefore, it is possible to lengthen the time for holding the potential of the pixel electrode, and a driving mode for reducing the refresh rate can be applied. Furthermore, even when a driving mode for reducing the refresh rate is applied in the liquid crystal display device, since it is possible to suppress the change in the voltage applied to the liquid crystal layer for a long time, it is possible to further prevent the user from perceiving image flicker. Therefore, it is possible to achieve low power consumption and improve the display quality. Here, the effect of reducing the refresh rate will be described. Eye fatigue is of two types: nervous system fatigue and muscular system fatigue. Nervous system fatigue is caused by continuously looking at the light-emitting and blinking screens of a liquid crystal display device for a long time, and its brightness stimulates the retina, nerves, and brain of the eyes, causing fatigue. Muscular system fatigue is caused by overusing the ciliary muscles used when adjusting focus.

[0358]

[0359]

[0360] FIG. 20(A) shows a schematic diagram representing the display of a conventional liquid crystal display device. As shown in FIG. 20(A), in the display of a conventional liquid crystal display device, image rewriting is performed 60 times per second. Continuously looking at such a screen for a long time stimulates the user's retina, nerves, and brain, which may cause eye fatigue.

[0361] In one aspect of the present invention, a transistor with an extremely low off-current, for example, a transistor using an oxide semiconductor, is applied to the pixel portion of the liquid crystal display device. Further, the liquid crystal element has a large-capacity element. By these means, it becomes possible to suppress the leakage of the charge accumulated in the capacitive element, so that even if the frame frequency is lowered, the luminance of the liquid crystal display device can be maintained.

[0362] That is, as shown in FIG. 20(B), for example, it becomes possible to rewrite an image once every 5 seconds, so that it is possible to view the same video as much as possible, and the flicker of the screen visually recognized by the user is reduced. As a result, the stimulation of the user's retina, nerves, and brain is reduced, and the fatigue of the nervous system is alleviated.

[0363] According to one aspect of the present invention, an eye-friendly liquid crystal display device can be provided.

[0364] Note that the configurations and methods shown in the present embodiment, such as the configurations and methods shown in other embodiments, can be used in appropriate combination.

[0365] (Embodiment 7) In the present embodiment, a configuration example of an electronic device to which a display device according to one aspect of the present invention is applied will be described. Further, in the present embodiment, a display module to which a display device according to one aspect of the present invention is applied will be described with reference to FIG. 21. The display module 8000 shown in FIG. 21 includes an upper cover 8001 and a lower cover 8002.

[0366] The display module 8000 shown in FIG. 21 is between an upper cover 8001 and a lower cover 8002. Between them, there are a touch panel 8004 connected to the FPC8003, and a display panel 8006, a backlight unit 8007, a frame 8009, a printed circuit board 8010, and a battery 8011. Note that the backlight unit 8007, the battery 8011, the touch panel 8004, etc. may not be provided.

[0367] The display device according to one aspect of the present invention can be used, for example, for the display panel 8006.

[0368] The upper cover 8001 and the lower cover 8002 can be appropriately changed in shape and dimensions according to the sizes of the touch panel 8004 and the display panel 8 006.

[0369] The touch panel 8004 can be used by superimposing a touch panel of a resistive film type or a capacitive type on the display panel 8 006. Also, it is possible to provide a touch panel function on the counter substrate (sealing substrate ) of the display panel 8006. Alternatively, it is also possible to provide an optical sensor in each pixel of the display panel 8 006 to form an optical touch panel. Or, it is also possible to provide a touch sensor electrode in each pixel of the display panel 8 006 to form a capacitive touch panel.

[0370] The backlight unit 8007 has a light source 8008. The light source 8008 may be provided at the end of the backlight unit 8007, and a light diffusing plate may be used.

[0371] The frame 8009 has, in addition to the protection function of the display panel 8006, a function as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed circuit board 8010. Also, the frame Mu 8009 may have a function as a heat sink.

[0372] The printed circuit board 8010 has a signal processing circuit for outputting a power supply circuit, a video signal, and a clock signal. As the power supply for supplying power to the power supply circuit, it may be an external commercial power supply or a power supply by a separately provided battery 8011. The battery 8011 can be omitted when using a commercial power supply.

[0373] In addition, members such as a polarizing plate, a retardation plate, and a prism sheet may be additionally provided in the display module 8000.

[0374] FIG. 22 is an external view of an electronic device including a display device according to an aspect of the present invention.

[0375] Examples of the electronic device include a television device (also referred to as a television or a television receiver), a monitor for a computer, a camera such as a digital camera and a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device), a portable game machine, a portable information terminal, an audio reproduction device, and a large game machine such as a pachinko machine.

[0376] FIG. 22(A) is a portable information terminal, which is composed of a main body 1001, a housing 1002, display units 1003a, 1003b, etc. The display unit 1003b is a touch panel, and by touching the keyboard button 1004 displayed on the display unit 1003b, screen operation and character input can be performed. Of course, the display unit 1003a may be configured as a touch panel. The transistor shown in the above embodiment is used as a switching element for a liquid crystal panel By manufacturing an organic light-emitting panel and applying it to the display units 1003a and 1003b, a highly reliable portable information terminal can be obtained.

[0377] The portable information terminal shown in Fig. 22(A) has functions such as displaying various information (still images, moving images, text images, etc. ), displaying a calendar, date, or time on the display unit, operating or editing the information shown on the display unit, and controlling processing by various software (programs). It can also be configured to have external connection terminals ( earphone terminals, USB terminals, etc.) and a recording medium insertion part on the back or side of the housing.

[0378] Moreover, the portable information terminal shown in Fig. 22(A) may be configured to be able to wirelessly transmit and receive information. It is also possible to configure it to purchase and download desired book data, etc. from an e-book server wirelessly.

[0379] Fig. 22(B) shows a portable music player. The main body 1021 is provided with a display unit 1023, a fixing part 1022 for wearing on the ear, a speaker, operation buttons 1024, an external memory slot 1025, etc. By manufacturing a liquid crystal panel or an organic light-emitting panel using the transistor shown in the above embodiment as a switching element and applying it to the display unit 1023, a more reliable portable music player can be obtained.

[0380] Furthermore, if the portable music player shown in Fig. 22(B) is equipped with an antenna, a microphone function, and a wireless function and is linked with a mobile phone, it is possible to have a hands-free conversation wirelessly while driving a vehicle, etc.

[0381] Figure 22(C) shows a mobile phone, which is composed of two housings, namely housing 1030 and housing 1031. Housing 1031 is equipped with a display panel 1032, a speaker 1033, a microphone 1034, a pointing device 1036, a camera 1037, an external connection terminal 1038 and so on. In addition, housing 1030 is equipped with a solar cell 1040 for charging the mobile phone, an external memory slot 1041 and so on. The antenna is hidden inside housing 1031. By applying the transistor described in the above embodiment to the display panel 1032, a highly reliable mobile phone can be obtained.

[0382] In addition, the display panel 1032 is equipped with a touch panel, and a plurality of operation keys 1035 shown by dotted lines are displayed in Figure 22(C). Note that a boost circuit for boosting the voltage output by the solar cell 1040 to the voltage required for each circuit is also implemented.

[0383] The display direction of the display panel 1032 changes appropriately according to the usage form. In addition, since the camera 1037 is provided on the same surface as the display panel 1032, a video phone is possible. The speaker 1033 and the microphone 1034 are not limited to voice calls, and video phones, recording, playback, etc. are also possible. Furthermore, housing 1030 and housing 1031 can be slid and overlapped from the unfolded state as shown in Figure 22(C), enabling miniaturization suitable for portability.

[0384] The external connection terminal 1038 can be connected to various cables such as an AC adapter and a USB cable, enabling charging and data communication with a personal computer, etc. In addition, external Insert a recording medium into the memory slot 1041 to support storage and transfer of a larger amount of data is possible.

[0385] In addition to the above functions, those equipped with an infrared communication function, a television receiving function, etc. may also be acceptable.

[0386] FIG. 22(D) shows an example of a television apparatus. The television apparatus 1050 has a display unit 1053 incorporated in a housing 1051. The display unit 1053 can display an image is possible. Further, a CPU is built in a stand 1055 that supports the housing 1051 Applying the transistor described in the above embodiment to the display unit 1053 and the CPU makes it possible to obtain a highly reliable television apparatus 1050.

[0387] The operation of the television apparatus 1050 can be performed by an operation switch provided in the housing 1051 or a separate remote controller. Further, the remote control operation unit may be configured to include a display unit that displays information output from the remote control operation unit.

[0388] Note that the television apparatus 1050 is configured to include a receiver, a modem, etc. The receiver can receive more general television broadcasts, and further, by connecting to a communication network by wire or wirelessly via the modem, one-way (from the sender to the receiver) or two-way (between the sender and the receiver, or between the receivers, etc.) information communication is also possible. (between the sender and the receiver, or between the receivers, etc.) information communication is also possible.

[0389] Further, the television apparatus 1050 includes an external connection terminal 1054, a storage medium playback / recording unit 10 52, and an external memory slot. The external connection terminal 1054 is a USB cable or the like ​​It is connectable to various cables and can perform data communication with a personal computer or the like. In the recording and playback unit 1052 of the storage medium, a disk-shaped storage medium can be inserted, and data stored in the storage medium can be read and written to the storage medium. In addition, images, videos, etc. stored in the external memory 1056 inserted into the external memory slot can be projected onto the display unit 1053.

[0390] Further, when the off-leakage current of the transistor described in the above embodiment is extremely small, by applying the transistor to the external memory 1056 or the CPU, a highly reliable television device 1050 with sufficiently reduced power consumption can be obtained.

[0391] Note that the configurations and methods shown in this embodiment can be used in appropriate combination with the configurations and methods shown in other embodiments.

Explanation of Reference Numerals

[0392] 11 Pixel section 13 Pixel 13_1 Pixel 13_2 Pixel 14 Sub-pixel 14B Sub-pixel 14B_1 Sub-pixel 14B_2 Sub-pixel 14G Sub-pixel 14G_1 Sub-pixel 14G_2 Sub-pixel 14R Sub-pixel 14R_1 Sub-pixel 14R_2 Sub-pixel 14W_1 Sub-pixel 14W_2 Sub-pixel 16 Signal line drive circuit 17 Scanning line 17_1 Scanning line 17_2 Scanning line 17_3 Scanning line 18 Potential generation circuit 19 Capacitance line 25 Signal line 25_1 Signal line 25_2 Signal line 25_3 Signal line 31 Liquid crystal element 41 Light emitting element 43 Transistor 45 Transistor 47 Wiring 49 Wiring 50 Wiring 51 Gate insulating film 53 Inorganic insulating film 53a Insulating film 70 Electron gun chamber 72 Optical system 74 Specimen chamber 76 Optical system 78 Camera 80 Observation chamber 82 Film chamber 84 Electron 88 Substance 92 Fluorescent plate 100 Display device 102 Transistor 102a Transistor 103 Transistor 103a Transistor 103d Transistor 105 Capacitive element 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 Metal oxide film 308d Oxide semiconductor film 308e Oxide semiconductor film 308f Metal Oxide Film 309 Conductive Film 310a Conductive Film 310b Conductive Film 310c Conductive Film 310d Conductive Film 310e Conductive Film 310f Conductive Film 310g Conductive Film 310h Conductive Film 310i Conductive Film 310j Conductive Film 311 Insulating Film 311a Insulating Film 311b Insulating Film 312 Insulating Film 312a Insulating Film 312b Insulating Film 313 Insulating Film 314 Insulating Film 315 Conductive Film 316a Conductive Film 316b Conductive Film 316d Conductive Film 316e Conductive Film 317 Organic Insulating Film 317a Organic Insulating Film 318 Conductive Film 319 Conductive Film 319a Conductive Film 319b Conductive Film 320 Alignment Film 321 Liquid Crystal Layer 322 Liquid Crystal Element 336 Multilayer Film 336a Oxide Semiconductor Film 336b Oxide Semiconductor Film 342 Substrate 344 Light-Shielding Film 346 Colored Film 348 Insulating Film 350 Conductive Film 352 Alignment Film 362 Opening 364a Opening 364b Opening 364c Opening 364d Opening 371 Organic resin film 373 EL layer 375 Common electrode 1001 Body 1002 Housing 1003a Display section 1003b Display section 1004 Keyboard button 1021 Body 1022 Fixing section 1023 Display section 1024 Operation button 1025 External memory slot 1030 Housing 1031 Housing 1032 Display panel 1033 Speaker 1034 Microphone 1035 Operation key 1036 Pointing device 1037 Camera 1038 External connection terminal 1040 Solar cell 1041 External memory slot 1050 Television apparatus 1051 Housing 1052 Recording and playback section for memory medium 1053 Display section 1054 External connection terminal 1055 Stand 1056 External memory 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 first pixel having first to third sub-pixels, and a second pixel having fourth to sixth sub-pixels provided in a row next to the first pixel; the first and fourth sub-pixels are arranged in the same column and control light of the same color; the second, third, fifth and sixth sub-pixels are arranged in the same column, the second and sixth subpixels control light of the same color; the third and fifth sub-pixels control light of the same color; the first, third and fourth sub-pixels are always electrically connected to a first signal line; the second, fifth and sixth sub-pixels are always electrically connected to a second signal line; the first and second sub-pixels are always electrically connected to a first scan line; the third and sixth subpixels are always electrically connected to the second scan line; The fourth and fifth sub-pixels are always electrically connected to a third scanning line.

2. In claim 1, the first to third scanning lines extend in a row direction in a plan view, The display device, wherein the second scanning line has an area located between the first scanning line and the third scanning line in the plan view.

Images