Display device

Abstract

To provide a semiconductor device having a low off-state current or performing accurate display, or to provide a display device having a wide view angle or a screen with less burn-in, for example.SOLUTION: A circuit is configured by using a transistor having an oxide semiconductor (OS), particularly a thin-film MOS transistor having the oxide semiconductor. The oxide semiconductor is a substantially intrinsic semiconductor, therefore, which has a very low off-state current.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a semiconductor device, a display device, a liquid crystal display device, a light emitting device, a method for manufacturing the same, or In particular, the present invention relates to a thin film transistor using a semiconductor film having an oxide semiconductor. A semiconductor device, a display device, a liquid crystal display device, a light-emitting device, and the like, each of which has a circuit formed by a transistor. The present invention relates to a method for manufacturing the same or a method for driving the same. [Background technology]

[0002] Currently, amorphous silicon is used as a switching element in display devices such as liquid crystal displays. Thin-film transistors (TFTs) that use a silicon layer such as a capacitor as a channel layer are widely used. Thin-film transistors using amorphous silicon have low field-effect mobility, but This has the advantage that it can accommodate the increase in the area of ​​glass substrates.

[0003] Recently, thin-film transistors have been fabricated using metal oxides that exhibit semiconducting properties, and electronic devices have been developed. For example, among metal oxides, the technology of applying it to devices and optical devices is attracting attention. It is known that tin oxide, indium oxide, zinc oxide, etc. exhibit semiconductor properties. A thin film transistor in which a transparent semiconductor layer made of such a metal oxide is used as a channel forming region. A transistor is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-165532 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of one embodiment of the present invention is to provide a semiconductor device or the like with low off-state current. Another object of one embodiment of the present invention is to provide a semiconductor device or the like having high withstand voltage. An object of one embodiment of the present invention is to provide a semiconductor device or the like that can display an accurate image. An object of one embodiment of the present invention is to provide a display device or the like with a wide viewing angle. An object of one embodiment of the present invention is to provide a display device or the like in which image sticking on the screen is reduced. The description of these problems does not preclude the existence of other problems. It is not necessary for one aspect of the present invention to solve all of these problems. The problem is self-evident from the description, drawings, claims, etc. Other issues can be extracted from the descriptions in the drawings, claims, etc. [Means for solving the problem]

[0006] In order to solve the above problems, a semiconductor device having an oxide semiconductor (OS) A circuit is constructed using a transistor having an oxide semiconductor, particularly a thin-film MOS transistor having an oxide semiconductor. The oxide semiconductor is essentially an intrinsic semiconductor. Low off-state current or high breakdown voltage.

[0007] Therefore, one aspect of an embodiment of the present invention is a first transistor and a second transistor. A pixel having a first liquid crystal element and a second liquid crystal element, The first terminal of the first transistor is electrically connected to a first wiring, and the second terminal of the first transistor is The first transistor is electrically connected to the first liquid crystal element. The gate of the first transistor is connected to a second wiring. and a first terminal of the second transistor is electrically connected to a first wiring. a second terminal of the second transistor electrically connected to the second liquid crystal element; The gate of the second transistor is electrically connected to a third wiring, and the gate of the first transistor is electrically connected to a third wiring. The liquid crystal display device according to claim 1, wherein the first transistor and the second transistor have an oxide semiconductor. A display device is provided.

[0008] Alternatively, one aspect of the embodiment of the present invention is a first transistor, a second transistor, and a first a pixel having a first liquid crystal element and a second liquid crystal element, The first transistor is electrically connected to a first wiring, and the second terminal of the first transistor is The gate of the first transistor is electrically connected to the second wiring and the second liquid crystal element. a first terminal of the second transistor electrically connected to a third wiring; a second terminal of the second transistor electrically connected to the second liquid crystal element; The gate of the second transistor is electrically connected to the second wiring, and the gate of the first transistor is electrically connected to the second wiring. The liquid crystal display device according to claim 1, wherein the first transistor and the second transistor have an oxide semiconductor. A display device is provided.

[0009] Alternatively, one aspect of the embodiment of the present invention is a first transistor, a second transistor, and a first a pixel having a first liquid crystal element and a second liquid crystal element, The first transistor is electrically connected to a first wiring, and the second terminal of the first transistor is The gate of the first transistor is electrically connected to the second wiring and the second liquid crystal element. a first terminal of the second transistor electrically connected to the first wiring; a second terminal of the second transistor electrically connected to the second liquid crystal element; The gate of the second transistor is electrically connected to the second wiring, and the first transistor the first transistor and the second transistor each include an oxide semiconductor. A liquid crystal display is provided.

[0010] Alternatively, one aspect of the embodiment of the present invention is a transistor, a first liquid crystal element, and a second liquid crystal element. and a capacitor element, and a first terminal of the transistor is electrically connected to a first wiring. a second terminal of the transistor electrically connected to the first liquid crystal element; The gate of the transistor is electrically connected to a second wiring, and the first terminal of the capacitance element is The first terminal of the capacitance element is electrically connected to the first liquid crystal element, and the second terminal of the capacitance element is electrically connected to the second liquid crystal element. The transistor is electrically connected to a crystal element, and the transistor has an oxide semiconductor. A liquid crystal display device is provided.

[0011] Alternatively, one aspect of the embodiment of the present invention is a first transistor, a second transistor, and a first a pixel including a first liquid crystal element, a second liquid crystal element, and a capacitor element, The first terminal of the first transistor is electrically connected to a first wiring, and the second terminal of the first transistor is is electrically connected to the first liquid crystal element, and the gate of the first transistor is connected to a second a first terminal of the second transistor electrically connected to the first wiring; or a second terminal of the first transistor, The second terminal of the second transistor is electrically connected to the second liquid crystal element. The first terminal of the capacitance element is electrically connected to the second wiring. a second terminal of the capacitance element electrically connected to the second liquid crystal element; the first transistor and the second transistor include an oxide semiconductor. The liquid crystal display device is characterized by the above.

[0012] In the drawings, the size, layer thickness, or area may be exaggerated for clarity. Therefore, it is not necessarily limited to that scale.

[0013] Note that the diagram is a schematic representation of an ideal example, and is not limited to the shapes or values ​​shown in the diagram. For example, there are variations in shape due to manufacturing techniques, variations in shape due to errors, and noise. Variations in signals, voltages, or currents due to timing differences, or variations in signals, voltages, Or, it is possible to include current variation.

[0014] In addition, technical terms may be used for the purpose of describing a specific embodiment or example. However, one aspect of the invention should not be interpreted as being limited by technical terms.

[0015] In addition, undefined terms (including scientific and technical terms such as technical terms or academic terms) are generally It is possible to use the term as meaning equivalent to the general meaning understood by a person skilled in the art. Any words defined herein shall be construed in a manner consistent with the background of the relevant art. is preferred. Effect of the Invention

[0016] In the disclosed invention, as an example, a transistor including an oxide semiconductor and having low off-state current This is used to construct the circuit. This prevents unnecessary current from leaking in. Therefore, accurate display is possible. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Diagram 2] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Diagram 3] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 4] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Diagram 5] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 6] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 7] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 8] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 9] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 10] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 11] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 12] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 13] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 14] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 15] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 16] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 17] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 18] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 19] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 20] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 21] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Figure 22] FIG. 1 is a circuit diagram illustrating a semiconductor device. [Diagram 23] 1 is a cross-sectional view illustrating a semiconductor device. [Figure 24] 2A to 2C illustrate a manufacturing process of a semiconductor device. [Diagram 25] 1A to 1C are diagrams illustrating a method of operating a semiconductor device. [Figure 26] 1A to 1C are diagrams illustrating electronic devices. [Figure 27] 1A to 1C are diagrams illustrating electronic devices. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment will be described with reference to the drawings. However, the embodiment may be different from the embodiment. The present invention can be implemented in any manner without departing from the spirit and scope of the present invention. It will be easily understood by those skilled in the art that the present invention may be modified in various ways. In addition, in the configuration described below, A part or a part having a similar function is indicated by a common reference numeral in different drawings, and the same part is indicated by a common reference numeral in different drawings. Alternatively, detailed description of parts having similar functions will be omitted.

[0019] In this specification, a transistor includes a gate, a drain, and a source. It is an element that has at least three terminals. And the drain (drain terminal, drain Between the source (source terminal, source region or source electrode) and the It has a channel region and allows a current to flow through the drain, the channel region, and the source. Here, the source and drain are the same as the structure or operating conditions of the transistor. It is difficult to determine which is the source and which is the drain because the Yes. Therefore, the part that functions as a source and the part that functions as a drain may not be referred to as a source or a drain. In that case, as an example, one of the source and the drain may be denoted as a first terminal, a first electrode, or a first region, and the other of the source and the drain may be denoted as a second end son, a second electrode, or a second region.

[0020] Note that in this specification and the like, terms such as first, second, and third are used to describe various elements, members, regions, layers, and areas separately from others. Therefore, terms such as first, second, and third do not limit the number of elements, members, regions, layers, areas, etc. Furthermore, for example, it is possible to replace "first" with "second" or "third", etc.

[0021] Note that in this specification and the like, in the drawings or sentences described in a certain embodiment, it is possible to extract a part thereof to form an aspect of the invention. Therefore, when a drawing or sentence describing a certain part is provided, the content obtained by extracting a part of the drawing or sentence thereof is also disclosed as an aspect of the invention and is assumed to be able to form an aspect of the invention. Therefore, for example, in a drawing or sentence in which one or more active elements (such as transistors and diodes), wirings, passive elements (such as capacitive elements and resistive elements), conductive layers, insulating layers, semiconductor layers, organic materials, inorganic materials, components, devices, operation methods, manufacturing methods, etc. are described, it is possible to extract a part thereof to form an aspect of the invention . For example, from a circuit diagram composed of N (N is an integer) circuit elements (such as transistors and capacitive elements), M (M is an integer and M < N) circuit elements (such as transistors and capacitors can be taken out to form an aspect of the invention. For example, from a circuit diagram composed of N (N is an integer) circuit elements (such as transistors and capacitive elements), It is possible to extract (such as elements) to constitute one aspect of the invention. As another example, from a cross-sectional view composed of N (N is an integer) layers, M (M is an integer and M < N) layers can be extracted to constitute one aspect of the invention. As yet another example, from a flowchart composed of N ( N is an integer) elements, M (M is an integer and M < N) elements can be extracted to constitute one aspect of the invention.

[0022] In addition, in this specification and the like, at least the content described in the figures (even a part in the figures) is disclosed as one aspect of the invention and can constitute one aspect of the invention. Therefore, for a certain content, if it is described in the figures, even if it is not described in words, that content is disclosed as one aspect of the invention and can constitute one aspect of the invention. Similarly, for a figure obtained by extracting a part of the figure, it is also disclosed as one aspect of the invention and can constitute one aspect of the invention.

[0023] In this specification and the like, a semiconductor device refers to a device having a circuit including semiconductor elements (such as transistors, diodes, thyristors, etc.). However, it may also be called a semiconductor device for all devices that can function by utilizing semiconductor characteristics, or for devices having semiconductor materials.

[0024] In addition, a display device refers to a device having display elements. The display device may include a plurality of pixels including display elements. The display device may also include a peripheral drive circuit for driving a plurality of pixels. The peripheral drive circuit for driving a plurality of pixels may include a plurality of pixel ​​​The display device may be formed on the same substrate as the element. The peripheral driving circuits arranged on the board by the so-called chip-on-glass (COG) It may include an IC chip connected to the board or an IC chip connected by TAB or the like. The display device is made up of IC chips, resistors, capacitors, inductors, transistors, etc. The flexible printed circuit (FPC) may include a flexible printed circuit (FPC) to which the The display device is connected via a flexible printed circuit (FPC) or the like, and the IC chip Printed wiring with resistors, capacitors, inductors, transistors, etc. The display device may include a polarizing plate or a retardation plate. The display device may include a lighting device, a housing, an audio input / output device, a light, and It may also include a sensor.

[0025] The lighting device includes a backlight unit, a light guide plate, a prism sheet, a diffusion sheet, a reflector, It has a sheet, a light source (LED, cold cathode fluorescent lamp, etc.), a cooling device (water-cooled, air-cooled), etc. is also good.

[0026] The light-emitting device refers to a device having a light-emitting element or the like. When the light emitting device has an element, the light emitting device is a specific example of a display device.

[0027] The reflecting device is a device that has a light reflecting element, a light diffractive element, a light reflecting electrode, etc. This refers to.

[0028] The liquid crystal display device refers to a display device having a liquid crystal element. There are visual, projection, transmissive, reflective, and semi-transmissive types.

[0029] The driving device refers to a device having semiconductor elements, electric circuits, and electronic circuits. For example, a transistor that controls the input of a signal from a source signal line to a pixel (a selection transistor) (sometimes called a phototransistor, switching transistor, etc.) The transistors that supply voltage or current to the light-emitting element are driven by Furthermore, a circuit for supplying a signal to the gate signal line (a gate driver, A circuit that supplies signals to the source signal lines (sometimes called a source driver circuit, etc.) A pixel driver (sometimes called a pixel driver or a source line driver circuit) is an example of a driver device.

[0030] In addition, display devices, semiconductor devices, lighting devices, cooling devices, light-emitting devices, reflecting devices, driving devices, etc. For example, a display device may include a semiconductor device and a light emitting device. Alternatively, the semiconductor device may have a display device and a driver. There may be cases where this is the case.

[0031] (Embodiment 1) In this embodiment, a transistor having an oxide semiconductor, particularly a transistor having an oxide semiconductor in an active layer, A semiconductor device or the like (display device or light-emitting device) configured using a thin film transistor having An example of a transistor including an oxide semiconductor will be described with reference to the drawings. Since the off-state current is low, the off-state current can be reduced by using a semiconductor device including an oxide semiconductor. This reduces the number of defects caused by current, resulting in a more accurate display. In addition, a transistor including an oxide semiconductor has a high withstand voltage. It operates normally even when a voltage is applied, and the off-state current is low when a high voltage is applied. Therefore, problems caused by the off-current can be reduced.

[0032] In addition, thin-film transistors that have an I-type (intrinsic) oxide semiconductor layer in the active layer have a low off-current. The oxide semiconductor layer is particularly preferably made to be an i-type (intrinsic) oxide semiconductor layer. , dehydration or dehydrogenation is effective.

[0033] FIG. 1 illustrates a configuration example of a semiconductor device or the like described in this embodiment. , and a pixel 100. The pixel 100 constitutes one pixel.

[0034] In this specification, one pixel refers to one element whose brightness can be controlled. For example, one pixel represents one color element, and the brightness is expressed by one color element. Therefore, in this case, a color display device having R (red), G (green), and B (blue) color elements is used. In this case, the smallest unit of an image is composed of three pixels: an R pixel, a G pixel, and a B pixel. However, the number of color elements is not limited to three, and more than three colors may be used. You can use colors other than B. For example, you can add white to make it RGBW (W is white). Or, for example, yellow, cyan, magenta, emerald green, It is possible to add one or more colors such as vermilion. Or, at least one color in RGB. Similar colors can be added to RGB, e.g. as R, G, B1, B2. B1 and B2 are both blue, but they have slightly different wavelengths. It is also possible to use 1, R2, G, and B. By using such color elements, By using such color elements, power consumption can be reduced. It is possible to reduce it.

[0035] In addition, when controlling the brightness of one color element using multiple areas, For example, when performing area gradation or when using sub-pixels (sub-pixels), When a pixel has multiple regions that control the brightness of one color element, In some cases, gradation is expressed as a whole. In that case, one area for controlling brightness is regarded as one pixel. In other words, one color element is made up of multiple pixels. However, even if there are multiple areas that control brightness within one color element, they can be grouped together as follows: One color element may be one pixel. In that case, one color element is composed of one pixel. In addition, when controlling the brightness of one color element using multiple regions, In this case, the size of the area that contributes to the display may differ depending on the pixel. In the brightness control area, which has multiple color elements, the signal supplied to each is slightly In other words, the viewing angle may be increased by changing the color of each color element. In addition, it is possible that the potentials of the pixel electrodes of the multiple regions are different from each other. As a result, the voltage applied to the liquid crystal molecules varies depending on the pixel electrode. It can be made wider.

[0036] When explicitly stating one pixel (three colors), R, G, and B pixels are considered to be one pixel. When it is explicitly stated as one pixel (one color), it refers to one color element. In this case, when there are multiple regions, they are considered as one pixel.

[0037] The pixel 100 includes a transistor 101a, a transistor 101b, a display element 102a, and a display The transistor 101 includes an element 102b, a capacitor 103a, and a capacitor 103b. The gate of the transistor 101a is connected to the wiring 104a. The second terminal of the transistor 101a is connected to the wiring 105a. The second terminal of the display element 102a is connected to the wiring 107a. A first terminal of the capacitance element 103a is connected to a first terminal of the display element 102a. A second terminal of the capacitor 103a is connected to a wiring 106a. The gate of the transistor 101b is connected to the wiring 104b. The first terminal of the transistor 101b is connected to the wiring 105a. The second terminal of the display element 102b is connected to a wiring The first terminal of the capacitance element 103b is connected to the first terminal of the display element 102b. The second terminal of the capacitor 103b is connected to the wiring 106b. There are.

[0038] The transistor 101a or the transistor 101b is a display element 102a (a capacitor element Whether to supply a signal to the display element 102b (capacitor element 103a) or the display element 102b (capacitor element 103b) Therefore, it is possible to select either the transistor 101a or the transistor 101b. The transistor 101b can function as a switch. The resistor 101a or the transistor 101b is a switching transistor. The transistor can function as a selection transistor.

[0039] In this specification, an example of a transistor is a multi-gate transistor having two or more gate electrodes. A multi-gate transistor can be used. Since the gate regions are connected in series, a structure in which multiple transistors are connected in series is formed. The multi-gate structure reduces the off-current and improves the breakdown voltage of the transistor (improving reliability). Or, by using a multi-gate structure, when operating in the saturation region, The current between the drain and source does not change much even if the voltage between the drain and source changes. It is possible to obtain voltage-current characteristics with a flat slope without any distortion. By utilizing the voltage-current characteristics of the As a result, it is possible to realize a load such as a differential circuit or a current mirror circuit with good characteristics. It is possible to achieve this.

[0040] An example of a transistor is a structure in which gate electrodes are arranged above and below a channel. A transistor having a structure in which gate electrodes are arranged above and below the channel can be applied. By doing so, the circuit configuration becomes like multiple transistors connected in parallel. As a result, the channel area increases, and the current value can be increased. A structure in which gate electrodes are arranged above and below makes it easier for a depletion layer to form. , the S value can be improved.

[0041] An example of a transistor is a transistor having a structure in which a gate electrode is disposed above a channel region. a structure in which the gate electrode is disposed under the channel region; a positive staggered structure; and a reverse staggered structure. A structure in which the channel region is divided into a plurality of regions, a structure in which the channel regions are connected in parallel, or A transistor having a structure in which channel regions are connected in series can be used.

[0042] As an example of a transistor, a source electrode or A transistor with an overlapping drain electrode can be used. By making the structure such that the source electrode and drain electrode overlap the This can prevent the operation from becoming unstable due to charge accumulating in a portion of the panel region.

[0043] As an example of the transistor, a transistor having a structure provided with an LDD region can be used. By providing the LDD region, it is possible to reduce the off-current or improve the breakdown voltage of the transistor (signal By providing an LDD region, it is possible to improve the reliability. When in operation, the drain current does not change significantly even if the voltage between the drain and source changes. This allows obtaining voltage-current characteristics with a flat slope without any need for a

[0044] Here, the capacitance element 103a or the capacitance element 103b is a display element 102a or a display The display element 102b has a function of holding a voltage supplied thereto. a or the capacitor element 103b is a pixel capacitor of the display element 102a or the display element 102b. Therefore, the capacitor 103a or the capacitor 103b has a function of holding the potential of the electrode. 03b can function as a storage capacitor or an additional capacitor.

[0045] Here, the wirings arranged extending in the left-right direction, such as the wiring 104a and the wiring 104b, are The wiring 104a may be connected to the gate of a transistor included in the pixel. Wires extending in the left-right direction, such as the wire 104b, are used as gate signal lines, gate wiring lines, etc. The wiring 104a and the wiring 104b may have functions such as a gate line, a gate line, etc. In this way, the wiring extending in the left and right direction is supplied with signals that select one row at a time, In some cases, the signal is scanned. The wiring extending in the left and right direction is called scan signal line, scan wiring, scan line, etc. What functions can it have?

[0046] Alternatively, like the wiring 105a, the wiring arranged to extend in the vertical direction is a transistor of each pixel. The wiring 105a may be connected to the source or drain of the transistor. As shown in the figure, the wiring arranged in the vertical direction is called the source signal line, the source wiring, the source line, etc. Or, like the wiring 105a, it can be arranged to extend in the vertical direction. The wiring may carry data signals, video signals, source signals, etc. Therefore, wirings arranged to extend in the vertical direction, such as the wiring 105a, serve as data signal lines, It can have functions such as data wiring and data lines.

[0047] Here, the wiring 107a and the wiring 107b are connected to each other in all pixels. Alternatively, the wiring 107a and the wiring 107b may be arranged to extend in the left-right direction. The display element of each pixel can be connected to the display element of the pixel. Or, at least one row may have a signal. The wiring 107a and the wiring 107b can function as a common wiring, a counter electrode, etc. do.

[0048] Here, the wiring 106a and the wiring 106b are connected to other pixels, for example, the pixels on the left and right. It is possible that the power supply is connected to the power supply and that a certain voltage is being supplied. In some cases, a signal is supplied to at least one row. , common wiring, capacitance wiring, etc.

[0049] In this specification and the like, the term "display element," "display device having a display element," "light-emitting element," etc. A light-emitting device, which is a device having a light-emitting element, can be used in various forms or can have various elements. Examples of the display element, the display device, the light-emitting element, or the light-emitting device include EL (electroluminescence) elements (EL elements containing organic and inorganic materials, organic EL elements LEDs (white LEDs, red LEDs, green LEDs, blue LEDs, etc.) , transistors (transistors that emit light according to electric current), electron-emitting devices, liquid crystal devices, electron Ink, electrophoretic element, grating light valve (GLV), digital micromirror Dynamic Multiplier Device (DMD), Piezoelectric Ceramic Display, Carbon Nanotube, etc. A display medium whose contrast, brightness, reflectance, transmittance, etc. change due to magneto-electrical effects. An example of a display device using an EL element is an EL display. An example of a display device using electron-emitting devices is a field emission display. FED or SED type flat panel display (SED: Surface-conductive ction Electron-emitter Display) etc. Liquid crystal element An example of a display device using the liquid crystal display (transmissive liquid crystal display, semi-transmissive liquid crystal display, LCD display, reflective LCD display, direct-view LCD display, projection LCD display Examples of display devices using electronic ink or electrophoretic elements include , electronic paper, etc.

[0050] An example of an EL element includes an anode, a cathode, and an EL layer sandwiched between the anode and the cathode. One example of an EL layer is a device that uses light emission (fluorescence) from singlet excitons. Those that utilize emission from triplet excitons (phosphorescence), and those that utilize emission from singlet excitons (fluorescence). These include those that utilize light (photoluminescence) and those that utilize light emission from triplet excitons (phosphorescence), Those formed by organic matter, those formed by inorganic matter, those formed by organic matter those made of polymeric materials and inorganic materials; those made of low molecular weight materials; or those containing polymeric and low molecular weight materials. However, the EL element is not limited to this, and various elements can be used as the EL element.

[0051] An example of an electron-emitting device is a device that extracts electrons by concentrating a high electric field on a cathode. Specifically, examples of electron-emitting devices include Spindt-type and carbon nanotube (CNT ) type, MIM (Metal-Insulator-Metal) Al type, MIS (Metal-Insulator-Semiconductor) laminated Semiconductor type, MOS type, silicon type, thin film diode type, diamond Thin film types such as metal-insulator-semiconductor-metal type, HEED type, EL type, porous silicon However, there are other types of electron emitting elements, including but not limited to the above. A variety of things can be used as children.

[0052] An example of a liquid crystal element is a device that controls the transmission or non-transmission of light by the optical modulation action of liquid crystal. The element can be constructed by a pair of electrodes and a liquid crystal layer. The optical modulation of liquid crystals is achieved by applying an electric field (horizontal electric field, vertical electric field, or diagonal electric field) to the liquid crystal. Specifically, a liquid crystal element is a nematic liquid crystal element. tic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, discotic liquid crystal, thermotropic liquid crystal Pyc liquid crystal, lyotropic liquid crystal, low molecular weight liquid crystal, polymer liquid crystal, polymer dispersed liquid crystal (PDL C), Ferroelectric liquid crystal, antiferroelectric liquid crystal, main chain liquid crystal, side chain polymer liquid crystal, plasma address liquid Examples of liquid crystal driving methods include PALC and banana-shaped liquid crystal. , TN (Twisted Nematic) mode, STN (Super Twisted d Nematic mode, IPS (In-Plane-Switching) mode , FFS (Fringe Field Switching) mode, MVA (Mult i-domain Vertical Alignment mode, PVA (Patt erned Vertical Alignment) mode, ASV(Advance d Super View) mode, ASM (Axially Symmetric a ligned Micro-cell) mode, OCB (Optically Comp ensated birefringence mode, ECB (Electrical FLC (Ferrally Controlled Birefringence) mode, oelectric Liquid Crystal) mode, AFLC (AntiFe rroelectric Liquid Crystal) mode, PDLC (Poly mer Dispersed Liquid Crystal) mode, PNLC (Po lymer Network Liquid Crystal) mode, guest host mode Mode, Blue Phase mode, etc., but are not limited to these. Various liquid crystal elements and driving methods thereof can be used.

[0053] One example of the display method for electronic paper is the molecular display (optical anisotropy, dye molecular orientation, etc.), and those displayed by particles (electrophoresis, particle migration, particle rotation, phase change, etc.) (e.g., those that are displayed by the movement of one edge of the film, and those that are displayed by the color development / phase change of molecules. These are indicated by the light absorption of molecules, or by spontaneous electron-hole combinations. The display method may be electronic paper. Examples of the methods include microcapsule electrophoresis, horizontal migration electrophoresis, and vertical migration electrophoresis. Electrophoresis, spherical twist ball, magnetic twist ball, cylindrical twist ball method, charged toner , electronic powder, magnetic migration type, magnetic thermal type, electrowetting, light scattering (transparent / white Clouding), cholesteric liquid crystal / photoconductive layer, cholesteric liquid crystal, bistable nematic liquid Crystals, ferroelectric liquid crystals, dichroic dyes and liquid crystal dispersions, movable films, color development and erasure by leuco dyes, Photochromic, electrochromic, electrodeposition, flexible organic However, there are many types of electronic paper and its display methods, including but not limited to these. Here, by using microcapsule electrophoresis, This can solve the aggregation and precipitation of electrophoretic particles. It has advantages such as high efficiency, wide viewing angle, low power consumption, and memory properties.

[0054] In addition, display devices that require a light source, such as liquid crystal displays (transmissive liquid crystal displays), , Transflective LCD, Reflective LCD, Direct-view LCD, Projection LCDs, display devices using grating light valves (GLVs), digital An example of a light source for a display device using a digital micromirror device (DMD) is an Lectroluminescence, cold cathode tube, hot cathode tube, LED, laser light source, mercury lamp, etc. However, the present invention is not limited to this, and various light sources can be used as the light source. can be done.

[0055] Next, an example of the operation of the pixel 100 will be described. For example, after a selection signal is supplied to the wiring 104a, Then, a selection signal is supplied to the wiring 104b. In response to this, the transistor 101 a or the transistor 101b is turned on. As a result, the display element 10 Voltages of different magnitudes can be supplied to the display element 102a and the display element 102b. Therefore, the display elements 102a and 102b can be in different states. For example, when the display element 102a and the display element 102b have liquid crystal molecules, the liquid crystal It is possible to make the orientation of the molecules different from each other. Brightness (grayscale) of the displayed image In response to the above, the alignment state of the liquid crystal molecules in the display element 102a and the alignment state of the liquid crystal molecules in the display element 102b are By appropriately adjusting the orientation of the liquid crystal molecules, it is possible to improve the viewing angle characteristics. come.

[0056] It is preferable that the area of ​​the display element 102a and the area of ​​the display element 102b are approximately equal to each other. However, one aspect of the embodiment of the present invention is not limited to this, and the display element 102a It is also possible to make the area of ​​the display element 102b significantly different from that of the display element 102b. For example, The ratio of the area of ​​the display element 102a to the area of ​​the display element 102b can be set to approximately 1:2. This allows the viewing angle characteristics to be appropriately controlled. As one of the methods, it is possible to apply an area modulation method.

[0057] Here, "approximately equal" refers to differences within the range of manufacturing errors or differences that do not substantially affect operation. For example, "approximately equal" includes cases where the difference between the two is small. is less than 10%, and more preferably less than 5%.

[0058] When the area of ​​the display element 102a and the area of ​​the display element 102b are approximately equal, For example, the channel length or gate length of transistor 101a is b. Alternatively, the channel or gate length of transistor 1 The channel width or gate width of transistor 101a is Alternatively, the width of the gate of the transistor 101a may be approximately equal to the channel width or gate width of the transistor 101b. The ratio of the channel width to the channel length or gate length of the transistor 101b is The ratio of the gate width to the channel length or gate length is roughly equal. In this case, it is possible to provide a well-balanced signal. However, the present invention is not limited to the above.

[0059] In addition, when the area of ​​the display element 102a is larger than the area of ​​the display element 102b, In particular, the channel length or gate length of the transistor 101a is longer than that of the transistor 101b. The length of the channel or gate of the transistor 101 is smaller than the length of the gate of the transistor 101. The channel width or gate width of a is larger than the channel width or gate width of transistor 101b. Alternatively, as another example, the channel width or gate width of the transistor 101a is The ratio of the width to the channel or gate length is The ratio of the gate width to the channel length or gate length is larger than that of the gate width. However, one aspect of the embodiment of the present invention is to provide a signal Not limited.

[0060] In this way, the pixel 100 is divided into the display element 102a and the display element 102b. In other words, pixel 100 has two sub-pixels. In this case, one subpixel includes a transistor 101a, a display element 102a, and a capacitance element The other subpixel has a transistor 101b, a display element 102b, and It can be said that the capacitor 103b is included.

[0061] Note that the pixel 100 shown in FIG. 1 has two sub-pixels, but in one embodiment of the present invention, The shape is not limited to this, and it is also possible to have three or more sub-pixels.

[0062] Here, the transistor 101a and the transistor 101b are oxides having a small off-state current. Therefore, the pixel 100 may be made of a plurality of sub-pixels. Even if the capacitance value of the display element or the capacitance element is small, Alternatively, the voltage held by the capacitor may change due to the off-state current of the transistor. It is possible to reduce it.

[0063] The pixel 100 shown in FIG. 1 is controlled using the wiring 104a and the wiring 104b. Therefore, the selection time for each line is shorter. Increasing the voltage applied to the gate of transistor 101a and the gate of transistor 102b Here, the transistor 101a and the transistor 101b are preferably The transistor can be formed using an oxide semiconductor having a high breakdown voltage. Even if the voltage applied to the gate of transistor 101a and the gate of transistor 102b is increased, This allows the signal to be delivered quickly without damaging the transistor.

[0064] At least one of the capacitor 103a and the capacitor 103b is not provided. In the case where the capacitance element 103a and the capacitance element 103b are not provided, The circuit diagram for this case is shown in FIG. 2. In this case, a transistor with low off-state current is used as the transistor. For example, by using a transistor including an oxide semiconductor, Even if the capacitor 103b is not provided, the capacitance of the display element 102a and the capacitance of the display element 102b are not increased. In addition, the capacitor 103a and the capacitor 103b can be omitted. By doing so, the aperture ratio can be improved.

[0065] Note that the pixel circuit having the sub-pixel is not limited to that shown in FIG. 1 and FIG. 2. Various other configurations may be used. Another example of a pixel circuit having sub-pixels is shown in FIG.

[0066] FIG. 3 shows a circuit in which the wiring 104b is removed and the wiring 105b is added to the circuit in FIG. Therefore, the contents described in Fig. 1 and Fig. 2 can be applied to Fig. 3. In FIG. 3, the first terminal of the transistor 101b is connected to the wiring 105b. The gate of the transistor 101b is connected to a wiring 104a. Same as 1.

[0067] Here, the wirings arranged to extend in the vertical direction, such as the wiring 105a and the wiring 105b, It may be connected to the source or drain of a transistor included in a pixel. The wirings arranged to extend in the vertical direction, such as the wiring 105a and the wiring 105b, are used for the source signal. The wiring 105a may have the functions of a signal line, a source wiring, a source line, etc. Wires extending in the vertical direction, such as the wire 105b, carry data signals, video signals, and , a source signal, etc. may be supplied. Thus, the wiring arranged in the vertical direction is called data signal line, data wiring, data line, etc. It can have the following functions.

[0068] Next, an example of the operation of the pixel 100 shown in FIG. In response, the transistor 101a and the transistor 101b are turned on. At this time, the wiring 105a is supplied with a video signal corresponding to the display element 102a. A video signal corresponding to the display element 102b is supplied to the wiring 105b. The display element 102a and the display element 102b can be supplied with voltages of different magnitudes. Therefore, the display element 102a and the display element 102b are in different states. For example, the display element 102a and the display element 102b may have liquid crystal molecules. In this case, it is possible to make the alignment states of the liquid crystal molecules different from each other. The angular characteristics can be improved.

[0069] Next, still another example of a pixel circuit having a sub-pixel is shown in FIG.

[0070] FIG. 4 corresponds to the circuit in FIG. 1 with the wiring 104b removed. 3, the wiring 105b is removed. The contents described in FIG. 3 can be applied to FIG. 4. In FIG. 4, the transistor The first terminal of the transistor 101b is connected to the wiring 105a. The other components are connected to the wiring 104a. The rest are the same as those in FIG.

[0071] Next, an example of the operation of the pixel 100 shown in FIG. In response, the transistor 101a and the transistor 101b are turned on. At this time, the display element 102a and the display element 10b are connected to the wiring 105a. 2b, and a non-selection signal is supplied to the wiring 104a. In response, transistors 101a and 101b are turned off. Then, a pulse signal is supplied to the wiring 106a and the wiring 106b. The polarity (or magnitude) of the signal supplied to the line 106a and the signal supplied to the line 106b are reversed. For example, while a high potential signal is being supplied to the wiring 106a, A signal having a low potential is supplied to the wiring 106a. Alternatively, a signal having a positive potential is supplied to the wiring 106b. A signal of a negative potential is supplied to the wiring 106b. The signal supplied to 106b is varied at predetermined intervals. For example, A positive potential signal is supplied to the wiring 106a, and a negative potential signal is supplied to the wiring 106b. In the next period, a signal with a negative potential is supplied to the wiring 106a, and a signal with a negative potential is supplied to the wiring 106b. supply a positive potential signal. Then, these operations are repeated. As a result, the display element Since an averaged voltage is applied to the display element 102a and the display element 102b, the voltages of different magnitudes are Therefore, the state of the display element 102a and the display element 102b can be changed. For example, the display element 102a and the display element 102b can be in different states. When 02b has liquid crystal molecules, the alignment states of the liquid crystal molecules can be made different from each other. As a result, the viewing angle characteristics can be improved.

[0072] Next, still another example of a pixel circuit having a sub-pixel is shown in FIG.

[0073] 5, the wiring 104b and the transistor 101b are removed from the circuit in FIG. 1, and a capacitor element 503 is added to the circuit of FIG. , the transistor 101b is deleted and a capacitor 503 is added. FIG. 5 shows a circuit in which the transistor 101b is removed and a capacitor element 503 is added to the circuit in FIG. Therefore, the contents described in FIG. 1 to FIG. 4 are applicable to FIG. In FIG. 5, the first terminal of the display element 102b is connected to the first terminal of the capacitor element 503. The second terminal of the capacitor 503 is connected to the second terminal of the transistor 101a. Other than that, it is the same as FIG. 1, FIG. 3, or FIG. 4.

[0074] Next, an example of the operation of the pixel 100 shown in FIG. In response to this, the transistor 101a becomes conductive. Then, a video signal corresponding to the display element 102a and the display element 102b is supplied to the wiring 105a. Then, because the capacitive element 503 exists, the capacitance division causes the display element 102b to A voltage having a different magnitude is supplied to the display element 102a. a and the display element 102b can be in different states. For example, When the element 102a and the display element 102b have liquid crystal molecules, the alignment states of the liquid crystal molecules are mutually different. As a result, the viewing angle characteristics can be improved. .

[0075] Next, still another example of a pixel circuit having a sub-pixel is shown in FIG.

[0076] FIG. 6 corresponds to the circuit in FIG. 5 to which a transistor 501 is added. FIG. 6 shows a circuit in which the wiring 104b and the transistor 101b are removed from the circuit in FIG. 6 corresponds to the circuit of FIG. The wiring 105b and the transistor 101b are deleted from the circuit, and the capacitor 503 and the transistor 6 corresponds to the circuit in FIG. 4 with a transistor 501 added. The transistor 101b is removed, and a capacitor element 503 and a transistor 501 are added. Therefore, the contents described in FIG. 1 to FIG. 5 can be applied to FIG. In FIG. 6, the first terminal of the display element 102b is connected to the first terminal of the capacitance element 503. The second terminal of the capacitor 503 is connected to the second terminal of the transistor 101a. A gate of the transistor 501 is connected to the wiring 104a. The first terminal of the transistor 501 is connected to the wiring 105a. The terminal is connected to the first terminal of the display element 102b. 4, or similar to FIG.

[0077] Here, the transistor 501 can function as a resistor when in a conductive state. Therefore, the on-resistance of the transistor 501 is equal to the on-resistance of the transistor 101a. It is preferable that the resistance is higher than the resistance of the ion exchange resin, but an aspect of an embodiment of the present invention is not limited thereto. As an example, the channel length or gate length of the transistor 501 is a channel length or gate length. Or, as another example, transistor 50 The channel width or gate width of transistor 101a is smaller than the channel width or gate width of transistor 101b. Alternatively, as another example, the channel width or gate width of the transistor 501 is The ratio of the channel length or gate length to the channel width or gate width of the transistor 101a is and the channel length or gate length.

[0078] Next, an example of the operation of the pixel 100 shown in FIG. In response, the transistor 101a and the transistor 501 At this time, the display element 102a and the display element 102b are connected to the wiring 105a. Then, the capacitance of the capacitor 503 is divided and the transistor Due to the high on-resistance of the capacitor 501, the display element 102b has a different characteristic from the display element 102a. Therefore, the state of the display element 102a and the display element 102b is For example, the display element 102a and the display element 102b can be in different states. When 02b has liquid crystal molecules, the alignment states of the liquid crystal molecules can be made different from each other. As a result, the viewing angle characteristics can be improved. By providing the first terminal of the capacitor 503 or the first terminal of the display element 102b, This prevents electric charges from accumulating on the terminals of the display. As a result, the screen burn-in is reduced. This can reduce the amount of noise.

[0079] Note that the first terminal of the transistor 501 is connected to the wiring 105a. One aspect of the embodiment is not limited thereto. For example, as shown in FIG. The first terminal of the capacitor 503 or the first terminal of the transistor 101a is It can be connected to terminal 2.

[0080] In addition, in FIG. 1 to FIG. 7, a certain wiring and another wiring are combined into one, and the wiring is omitted. As a result, the number of wirings can be reduced. For example, the wiring 106a and the wiring 106b can be integrated into one. In other words, the wiring 106a and the wiring 106b can be integrated into the wiring 106a. In this case, the wiring 106b may be omitted. The one thus obtained is connected to the wiring 106a.

[0081] Alternatively, the wiring 106a and another wiring (for example, the wiring 106) of a pixel other than the pixel 100 may be connected. b) can be combined into one and the wiring can be omitted. The wiring 106b of another pixel is merged into the wiring 106a, and the wiring 106b of the other pixel is deleted. In that case, what was connected to the wiring 106b of another pixel is now the wiring 106b. It becomes connected to line 106a.

[0082] In this specification, the terms "active elements" and "passive elements" are used interchangeably. For all terminals of devices (capacitive elements, resistive elements, etc.), the connection destination is not specified. However, a person skilled in the art may be able to compose one aspect of the invention. If multiple connection destinations are possible, the connection destination of the terminal must be limited to a specific location. Therefore, active elements (transistors, diodes, etc.) and passive elements (capacitive elements It is possible to specify the connection destination of only some of the terminals of the Therefore, it may be possible to configure one embodiment of the invention.

[0083] In this specification and the like, if at least the connection destination of a certain circuit is specified, it is understood by those skilled in the art that If you are a person who has experience in the field of electronics, you may be able to identify the invention. In some cases, a person skilled in the art may be able to identify the invention by at least specifying the function. Therefore, even if the function of a circuit is not specified, if the connection destination is specified, it can be considered as an embodiment of the invention. and can constitute one embodiment of the invention. For a certain circuit, even if the connection destination is not specified, if the function is specified, it can be considered as one aspect of the invention. What is disclosed can constitute an embodiment of the invention.

[0084] In this specification, etc., anything explicitly stated as singular shall be understood to be singular. However, it is not limited to this, and it is also possible to have multiple. However, where something is explicitly stated as plural, it is preferable that it be plural. However, it is not limited to this and may be singular.

[0085] (Embodiment 2) FIG. 8 illustrates a configuration example of a semiconductor device or the like described in this embodiment. 8. The pixel portion 801 is a pixel portion 802. However, one aspect of the embodiment of the present invention is not limited to this. stomach.

[0086] In the pixel section 801, a plurality of pixels are arranged in a matrix. The pixel 100a and the pixel 100b are arranged side by side in the horizontal direction. The pixels 100c are arranged vertically. Each pixel is connected to the other pixels by wiring. The vertically arranged pixels are connected by wiring that runs vertically. The pixels arranged in the horizontal direction are connected by wiring extending in the left-right direction. For example, The pixel 100a and the pixel 100b are connected to each other by a wiring 104a. The pixel 100a and the pixel 100c are connected by a wiring 105a. For example, wiring extending in the left and right direction (capacitor wiring, gate line for another sub-pixel, another Sub-pixel source lines), wiring that connects all pixels (common wiring, power supply lines, etc.) Therefore, the pixels can be connected. The same can be said for the other pixels. and are similarly connected.

[0087] Here, the pixel 100a, pixel 100b, pixel 100c, etc. are, for example, the pixels shown in FIGS. 7.

[0088] In this specification and the like, pixels may be arranged (distributed) in a matrix. Here, the pixels being arranged (arranged) in a matrix means that the pixels are arranged vertically or horizontally. When the pixels are arranged in a straight line or in a jagged line, Therefore, for example, full color display using three color elements (e.g. RGB) If you do this, the dots of the three color elements will be arranged in a delta arrangement, in the case of a stripe arrangement. This includes cases where the images are arranged in a Bayer pattern or a mosaic pattern. The size of the display area may be different for each dot of the color element. This makes it possible to reduce power consumption or extend the life of the display element.

[0089] FIG. 9A shows an example of a pixel portion 801 and its peripheral circuits. The pixel portion 801 is disposed in the pixel portion 802. Therefore, the transistors and The layers and wiring are deposited, etched, and patterned simultaneously. In other words, the transistors and wirings in the pixel portion 801 are manufactured through the same process steps. They are formed at the same time and together on the same substrate. The material of the lines is the same in the pixel portion 801 .

[0090] In FIG. 9A, a circuit 502, a circuit 513, and a circuit 504 are formed on a substrate separate from a substrate 511. Thus, for example, the circuit 502, the circuit 513, or The circuit 504 is configured with an IC chip using a single crystal substrate or an SOI substrate. However, the circuit 502, the circuit 513, and / or the circuit 504 are COG (chip-on-gate) The semiconductor device may be mounted on a substrate 511 using a glass mounting.

[0091] Here, the circuit 502 has a function of supplying a signal to the wiring 104a and the like. The circuit 502 can function as a gate line driver circuit (scan driver). The circuit 513 has a function of supplying a signal to the wiring 105a and the like. The circuit 513 can function as a signal line driver circuit (data driver). The circuit 504 has a function of controlling the circuit 502 or the circuit 513. Thus, the circuit 504 includes a controller, a pulse generating circuit, a clock signal generating circuit, a common voltage generation circuit, timing generator circuit, image processing circuit, or power supply circuit, etc. It can have a function.

[0092] Note that in FIG. 9A, the circuit 502, the circuit 513, and the circuit 504 are formed on a substrate 511. However, one aspect of the embodiment of the present invention is not limited to this. For example, some of these circuits may be provided on the substrate 511. FIG. 9B shows an example in which the circuit 502 is provided over a substrate 511. In FIG. 9B, a transistor and a wiring included in a pixel portion 801 and a circuit 502 are included. The transistors and wirings are formed at the same time, etched at the same time, and patterned at the same time. In other words, the pixel section 801 and the circuit 502 are formed through the same process. They are formed at the same time and together on the same substrate. The materials of the wiring are the same in the pixel portion 801 and the circuit 502. When the transistor 801 includes an oxide semiconductor, the transistor of the circuit 502 also includes an oxide semiconductor. The oxide semiconductor is included.

[0093] In this way, the circuit 502 is formed together with the pixel portion 801, thereby reducing costs. In particular, when the circuit 502 is operated as a gate line driver circuit, The operating speed is not so high that, for example, the mobility of the transistor in the circuit 502 is high. Even if you don't have that, it can still work just fine.

[0094] As an example different from that shown in FIG. 9B, the circuit 513 or a part of the circuit 513 may be formed on a substrate. The circuit 513 may be provided in the wiring 105. It is possible to connect an analog switch (transfer gate) to a. Similarly, the circuit 504 or a part of the circuit 504 may be provided on the substrate 511 .

[0095] In this specification and the like, transistors can be formed using various substrates. The type of substrate is not limited to a specific one. An example of the substrate is a semiconductor substrate. Substrates (e.g. single crystal substrates or silicon substrates), SOI substrates, glass substrates, quartz substrates, plastic Includes stick substrate, metal substrate, stainless steel substrate, stainless steel foil Substrates with tungsten foil, tungsten substrates, substrates with tungsten foil, flexible substrates, laminated substrates Examples of the substrate include a glass substrate, a paper containing a fibrous material, or a base film. Examples of glass include barium borosilicate glass, aluminoborosilicate glass, and soda lime glass. Examples of flexible substrates include polyethylene terephthalate (PET), polystyrene (PS), and polystyrene (PS). Polyethylene naphthalate (PEN) and polyethersulfone (PES) are typical examples. The materials used for the adhesive include flexible plastics, acrylics, and other synthetic resins with flexibility. Examples of the polypropylene, polyester, vinyl, polyvinyl fluoride, or chlorine Examples of the base film include polyester, polyamide, polyimide, etc. In particular, semiconductor substrates, single crystal substrates, and SO By manufacturing transistors using I substrates, etc., the characteristics, size, shape, etc. This makes it possible to manufacture small-sized transistors with low variation in temperature and high current capability. When a circuit is constructed using such transistors, the power consumption of the circuit can be reduced or It is possible to achieve high integration of the circuits.

[0096] Note that a transistor is formed using a certain substrate and then transferred to another substrate. However, the transistor may be disposed on another substrate. In addition to the substrate on which the above-mentioned transistors can be formed, the substrates include paper substrates, cellophane substrates, and the like. substrates made of natural fibers (silk, cotton, hemp), synthetic fibers (nylon, Polyurethane, polyester) or regenerated fiber (acetate, cupra, rayon, regenerated The substrates used are made of synthetic polyester, leather, or rubber. This allows the formation of transistors with good characteristics and low power consumption. It is possible to manufacture devices that are less likely to break, heat resistant, lightweight, or thin.

[0097] All of the circuits required to realize a given function are mounted on the same substrate (e.g., glass It can be formed on a substrate, a plastic substrate, a single crystal substrate, an SOI substrate, etc. This reduces the number of components, thereby reducing costs, and reduces the number of connections to circuit components. This can improve reliability.

[0098] It is possible that all of the circuits required to realize a given function are not formed on the same substrate. In other words, part of the circuitry required to realize a given function is formed on a certain substrate. Another part of the circuitry required to realize a given function is formed on a different substrate. For example, some of the circuits required to realize a certain function can be made of glass. Another part of the circuitry required to realize a given function is formed on the single crystal substrate. (or SOI substrate). The single crystal substrate (also called IC chip) on which another part of the circuitry required for the semiconductor device is formed is called COG ( By using the Chip On Glass (Chip On Glass) method, the IC is connected to the glass substrate and then attached to the glass substrate. It is possible to place the chip on the board. Or, the IC chip can be placed on the board using TAB (Tape Auto) omated Bonding), COF(Chip On Film), SMT(Su Surface Mount Technology, or a printed circuit board, etc. In this way, part of the circuit is formed on the same substrate as the pixel section. This reduces the number of components, resulting in lower costs, and the number of connections to the circuit components. This reduces the power consumption and improves the reliability of the circuit. In many cases, circuits with high drive frequencies consume a lot of power. Then, such a circuit is formed on a substrate (such as a single crystal substrate) separate from the pixel section, and By using this IC chip, it is possible to prevent an increase in power consumption. do.

[0099] Since a transistor including an oxide semiconductor has a low off-state current, By using a semiconductor device, it is possible to reduce problems caused by off-current. This allows for a more accurate display.

[0100] In addition, thin-film transistors that have an I-type (intrinsic) oxide semiconductor layer in the active layer have a low off-current. The oxide semiconductor layer is particularly preferably made to be an i-type (intrinsic) oxide semiconductor layer. , dehydration or dehydrogenation is effective.

[0101] (Embodiment 3) In this embodiment, another example of the pixel 100 is shown.

[0102] The pixel 100 shown in FIGS. 1 to 7 has two sub-pixels. The number of sub-pixels is not limited to two. As an example, in the pixel 100 shown in FIG. An example of a case with three elements is shown in FIG.

[0103] The pixel 100 shown in FIG. 10 differs from the pixel 100 shown in FIG. This corresponds to the case where the transistor 10 further includes a display element 102c and a capacitor element 103c. The gate of the transistor 101c is connected to the wiring 104c. The second terminal of the transistor 101c is connected to the wiring 105a. The second terminal of the display element 102c is connected to a first terminal of the wiring 107c. The first terminal of the capacitance element 103c is connected to the first terminal of the display element 102c. A second terminal of the capacitor 103c is connected to a wiring 106c.

[0104] In the cases of FIGS. 2 to 4, the number of sub-pixels can be increased to configure the circuit. It is Noh.

[0105] Next, an example in which the pixel 100 shown in FIG. 5 has three sub-pixels is shown in FIG. The pixel 100 shown in FIG. 11 differs from the pixel 100 shown in FIG. 5 in that it has a display element 102c, a capacitance element The capacitance element 503b in FIG. The first terminal of the display element 102c corresponds to the capacitor element 503 in FIG. The second terminal of the capacitive element 503c is connected to the first terminal of the capacitive element 503b. The second terminal of the display element 102c is connected to the wiring 107c. A first terminal of the capacitance element 103c is connected to a first terminal of the display element 102c. A second terminal of the capacitor 103c is connected to a wiring 106c.

[0106] FIG. 12 shows an example in which some of the connections are different from those in FIG. 11. In FIG. 12, a capacitive element 50 The second terminal of transistor 3c is connected to the second terminal of transistor 101a. , similar to FIG. 11.

[0107] Next, an example in which the pixel 100 shown in FIG. 6 has three sub-pixels is shown in FIG. The pixel 100 shown in FIG. 13 differs from the pixel 100 shown in FIG. 6 in that it has a display element 102c, a capacitance element This corresponds to the case where the capacitor 503c and the transistor 501c are further included. The element 503b corresponds to the capacitor element 503 in FIG. 501b corresponds to the transistor 501 in FIG. 6. Alternatively, FIG. 13 corresponds to the transistor 501 in FIG. The pixel 100 shown in FIG. 1 has a transistor 501b and a transistor 501c added thereto. In FIG. 13, the first terminal of the display element 102c corresponds to the first terminal of the capacitance element 503c. The second terminal of the capacitance element 503c is connected to the first terminal of the capacitance element 503b. The gate of the transistor 501c is connected to the wiring 104a. A first terminal of the transistor 501c is connected to the wiring 105a. A second terminal of display element 102c is connected to a first terminal of display element 102c. The second terminal of the capacitor 103c is connected to the wiring 107c. The second terminal of the capacitance element 103c is connected to the first terminal of the capacitance element 102c. It is connected to 106c.

[0108] Note that the first terminal of the transistor 501b is connected to the wiring 105a. One aspect of the embodiment is not limited to this. For example, The terminal is connected to the first terminal of the capacitance element 503c or the second terminal of the capacitance element 503b. It is also possible for the system to continue.

[0109] Note that the first terminal of the transistor 501c is connected to the wiring 105a. One aspect of the embodiment is not limited to this. For example, The terminal is connected to the first terminal of the capacitance element 503b or the second terminal of the capacitance element 503b. It is also possible for the system to continue.

[0110] The second terminal of the capacitance element 503c is connected to the first terminal of the capacitance element 503b. One aspect of the embodiment of the present invention is not limited to this. For example, The terminal can also be connected to the second terminal of the capacitive element 503b, etc.

[0111] Since a transistor including an oxide semiconductor has a low off-state current, By using a semiconductor device, it is possible to reduce problems caused by off-current. This allows for a more accurate display.

[0112] In addition, thin-film transistors that have an I-type (intrinsic) oxide semiconductor layer in the active layer have a low off-current. The oxide semiconductor layer is particularly preferably made to be an i-type (intrinsic) oxide semiconductor layer. , dehydration or dehydrogenation is effective.

[0113] (Embodiment 4) In this embodiment, another example of the pixel 100 is shown.

[0114] The pixel 100 shown in FIG. 14 differs from the pixel 100 shown in FIG. The gate of the transistor 901 is connected to the wiring 90 The first terminal of the transistor 901 is connected to the first terminal of the display element 102b. The second terminal of the transistor 901 is connected to the first terminal of the capacitor 903. A second terminal of the capacitor 903 is connected to the wiring 906.

[0115] In this case, the capacitance element 903 is supplied to the display element 102b or the capacitance element 103b. The capacitor 903 has a function of controlling the amount of charge stored in the display element 102b. The pixel electrode has a function of holding the potential of the pixel electrode.

[0116] Here, the wiring 904 may be connected to a gate of a transistor included in each pixel. Therefore, the wiring 904 has the functions of a gate signal line, a gate wiring, a gate line, etc. Alternatively, a signal for selecting one row at a time is supplied to the wiring 904, and the signal is skipped. Therefore, the wiring 904 is a scan signal line, a scan wiring Alternatively, the wiring 904 may function as a capacitor element 903. The charge of the charge carrier can be controlled.

[0117] Here, the wiring 906 is connected to other pixels, for example, the pixels on the left and right. And a certain voltage is supplied, or a signal is supplied to at least one row. Therefore, the wiring 906 may have a function of a common wiring, a capacitance wiring, etc. It is possible.

[0118] Next, an example of the operation of the pixel 100 shown in FIG. In response, the transistor 101a and the transistor 10 At this time, the wiring 105a is connected to the display element 102a and the display element 102b. A video signal corresponding to the selection signal is supplied to the wiring 102b. A non-selection signal is then supplied to the wiring 104a. In response, transistors 101a and 101b are turned off. Then, a selection signal is supplied to the wiring 904. Then, the capacitor 903 and the capacitor 1 Charge redistribution occurs between the capacitive element 103b and the display element 102b. In the capacitor 903, the capacitor element 103b, and the display element 102b, the charges move. Then, a non-selection signal is supplied to the wiring 904. As a result, As a result, the voltage across the display element 102a and the display element 102b changes. Therefore, the display element 102a and the display element 10 For example, the display elements 102a and 2b can be in different states. When the display element 102b has liquid crystal molecules, the alignment states of the liquid crystal molecules are made different from each other. As a result, the viewing angle characteristics can be improved.

[0119] The area or capacitance of the capacitor 903 is smaller than the area or capacitance of the capacitor 103b. It is desirable that the difference between the voltage of the display element 102b and the voltage of the display element 102a is small. However, the difference between the voltages can be prevented from being too large. One aspect is not limited to this.

[0120] In addition, the channel length or gate length of the transistor 101a (or the transistor 101b) The length is approximately equal to the channel length or gate length of the transistor 901. In particular, the channel width or gate width of the transistor 101a is The width of the gate or channel of the transistor 101 is approximately equal to the width of the gate or channel of the transistor 101. The ratio of the channel width or gate width to the channel length or gate length of a transistor is This is smaller than the ratio of the channel width or gate width to the channel length or gate length of 1b. This makes it possible to supply signals to each display element in a well-balanced manner. The embodiment is not limited to these.

[0121] As an example, the channel of the transistor 101a (or the transistor 101b) The channel length or gate length of the transistor 901 is smaller than the channel length or gate length of the transistor 902. As another example, the channel of transistor 101a (or transistor 101b) The channel width or gate width is larger than the channel width or gate width of transistor 901. Or, as another example, the channel of transistor 101a (or transistor 101b) The ratio of the width or gate width to the channel or gate length of the transistor 901 is The ratio of the channel or gate width to the channel or gate length is greater than the ratio of the channel or gate width to the channel or gate length. In 01, since there is no need to pass a large current, the current capacity can be reduced. As a result, the aperture ratio can be improved. are not limited to these.

[0122] Here, the transistor 101a, the transistor 101b, and the transistor 901 are In addition, the pixel can be configured using an oxide semiconductor having a small off-state current. The pixel 100 is divided into a plurality of sub-pixels, and the capacitance value of the display element or the capacitance element is small. Even if the voltage held by the display element or capacitor is low, the off-current of the transistor It is possible to reduce the change.

[0123] It is possible to combine a certain wiring and another wiring into one and omit the wiring. As a result, it is possible to reduce the number of wirings, thereby improving the aperture ratio. For example, the wiring 906 and the wiring 106b can be integrated into one. Therefore, the wiring 906 and the wiring 106b are merged into the wiring 106b, and the wiring 906 is deleted. In that case, what was connected to the wiring 906 is now connected to the wiring 106b. You will be able to do so.

[0124] Alternatively, the wiring 106a and the wiring 106b can be integrated into one. The line 106a and the wiring 106b are combined into the wiring 106b, and the wiring 106a is deleted. In this case, what was connected to the wiring 106a is now connected to the wiring 106b. You will be able to do so.

[0125] Alternatively, the wiring 906 (or the wiring 106a or the wiring 106b) and a pixel other than the pixel 100 It is possible to combine the other wiring (for example, wiring 106b) having the same wiring into one, and omit the wiring. That is, the wiring 906 (or the wiring 106a or the wiring 106b) and the wiring of another pixel The wire 106a and the wire 106b are grouped together into a wiring 906 (or wiring 106a and wiring 106b) to form a separate image. It is possible to remove the original wiring 106b. In that case, it is necessary to connect it to the wiring 106b of another pixel. The one that was connected to the wiring 906 (or wiring 106a, wiring 106b) is now connected to the wiring 906. It becomes like this.

[0126] Alternatively, the wiring 904 and another wiring (for example, the wiring 104a ) into one, and the wiring can be omitted. It is possible to combine the pixel wiring 104a with the wiring 104a and delete the wiring 904. In that case, what was connected to the wiring 904 is now connected to the wiring 104a of another pixel. You will be able to do so.

[0127] The second terminal of the transistor 101b is further connected to a capacitor via the transistor 901. The transistor 901 and the capacitor 903 are connected to a wiring 906. It is possible to change the order of connections in 903. For example, as shown in FIG. The second terminal of the transistor 101b is connected to the transistor 901 through the capacitance element 903. 906 via the wiring 906.

[0128] Note that a capacitor is connected to a first terminal of the capacitor 903 or a second terminal of the transistor 901. As an example, it is possible to connect the element 913 to the pixel of FIG. A capacitive element 913 is added to the element 100, and a first terminal of the capacitive element 913 is connected to the 03 or the second terminal of the transistor 901. A second terminal of the transistor 913 is connected to a second terminal of the transistor 101b.

[0129] By providing the capacitor 913 in this manner, the voltage applied to the capacitor 903 is adjusted. It is possible.

[0130] For example, the area or capacitance of the capacitor 913 is It is preferable that the capacitance value is smaller than the capacitance value. As a result, the voltage of the display element 102b can be changed effectively. However, one aspect of the embodiment of the present invention is not limited thereto.

[0131] FIG. 17 shows a case where a capacitor 913 is added to the pixel 100 shown in FIG. A second terminal of the capacitor 913 is connected to the wiring 906. The second terminal can be connected to the wiring 106a or the wiring 106b.

[0132] Note that the second terminal of the capacitor 913 can be connected to various locations. For example, in the pixel 100 shown in FIG. 16, the second terminal of the capacitor 913 is connected to a transistor FIG. 18 shows an example in which the second terminal of pixel 101a is connected to the second terminal of pixel 101a. Similarly, FIG. For 00, the second terminal of the capacitance element 913 is connected to the second terminal of the transistor 101a. An example of this is shown in FIG.

[0133] It is possible to remove the capacitor 103a or the capacitor 103b. For example, FIG. 20 shows an example of the pixel 100 shown in FIG. 17 without the capacitor element 103b. .

[0134] Although the pixel 100 shown in FIGS. 14 to 20 has two sub-pixels, However, one aspect of the embodiment of the present invention is not limited to this, and the number of sub-pixels can be three or more. It is Noh.

[0135] As an example, the pixel 100 shown in FIG. 14 may be divided into three sub-pixels as shown in FIG. In FIG. 21, the gate of the transistor 101c is connected to the wiring 104a. A first terminal of the transistor 101c is connected to the wiring 105a. The second terminal of the display element 102b is connected to the second terminal of the display element 102c. A first terminal of the capacitor 102c is connected to a first terminal of the capacitor 103c. The second terminal of the transistor 901c is connected to the wiring 106c. The first terminal of the transistor 901c is connected to the wiring 904c. The second terminal of the transistor 901c is connected to the first terminal of the capacitor 90 The second terminal of the capacitor 903c is connected to the first terminal of the wiring 906c. Connected.

[0136] Note that the transistor 901, the capacitor 903, the wiring 906, and the wiring 904 in FIG. 21, the transistor 901b, the capacitor 903b, the wiring 906b, and the wiring 904 Equivalent to b.

[0137] For example, the area or capacitance of the capacitor 903b is equal to or larger than the area or capacitance of the capacitor 903c. It is preferable that the area or capacitance value of the capacitance element 103b is different from that of the capacitance element 103b. It is preferable that the area or capacitance of the display element 103c is different from that of the display element 103c. The area or capacitance of the display element 102b is different from the area or capacitance of the display element 102c. As a result, the voltages of the display elements in the plurality of sub-pixels are appropriately different. However, one aspect of the embodiment of the present invention is not limited to this. stomach.

[0138] 14 to the pixel 100 illustrated in FIG. 16. 21. A capacitor 913b and a capacitor 913c are added to the pixel 100 shown in FIG. 22 shows the case where the capacitor 913b is connected between the first terminal and the second terminal of the transistor 901b. A capacitor 913c is provided between the first terminal and the second terminal of the transistor 901c. It is provided between terminal 2.

[0139] In addition, even when there are three or more sub-pixels, a certain wiring and another wiring are combined into one, It is possible to omit wiring. As a result, it is possible to reduce the number of wiring. This makes it possible to improve the aperture ratio.

[0140] Since a transistor including an oxide semiconductor has a low off-state current, By using a semiconductor device, it is possible to reduce problems caused by off-current. This allows for a more accurate display.

[0141] In addition, thin-film transistors that have an I-type (intrinsic) oxide semiconductor layer in the active layer have a low off-current. The oxide semiconductor layer is particularly preferably made to be an i-type (intrinsic) oxide semiconductor layer. , dehydration or dehydrogenation is effective.

[0142] (Embodiment 5) In this embodiment, an oxide semiconductor that can be used in the display devices described in any of the first to fourth embodiments is described. An example of a transistor including a conductor layer and a manufacturing method thereof will be described in detail with reference to FIGS. 23 and 24. The parts and steps having the same or similar functions as those in the above-mentioned embodiment are the same as those in the above-mentioned embodiment. The same description will be omitted. is omitted.

[0143] In this specification, Y is formed on X, or Y is formed on X. When explicitly stating that Y is formed on X, it is limited to Y being formed directly on X. If there is no direct contact, that is, if there is another object between X and Y, Here, X and Y are objects (e.g., devices, elements, circuits, wiring, electrodes, etc.). , terminal, conductive film, layer, etc.).

[0144] Thus, for example, it is not necessary to explicitly state that layer Y is formed on (or on top of) layer X. In the case of a layer mounted on a substrate, layer Y may be formed directly on layer X, or layer X may be formed directly on layer Y. Another layer (such as layer Z) is formed adjacent to it, and layer Y is formed directly on top of it. In addition, the other layer (e.g., layer Z) may be a single layer or , and may be multi-layered (laminated).

[0145] Furthermore, the same applies when it is explicitly stated that Y is formed above X. This is not limited to Y being directly on top of X, but includes the presence of another object between X and Y. For example, if a layer Y is formed above a layer X, In this case, layer Y is formed directly on layer X, and layer X is formed directly on layer Y. Another layer (such as layer Z) is formed, and layer Y is formed directly on top of it. The other layer (e.g., layer Z) may be a single layer or a multi-layer ( Lamination) may also be used.

[0146] In addition, Y is formed on X, Y is formed on X, or Y is formed above X When explicitly stating that "Y is formed diagonally above X," this also includes the case where Y is formed diagonally above X. do.

[0147] <Example of transistor configuration> A transistor including an oxide semiconductor layer which can be used in the display devices described in any of Embodiments 1 to 4. The transistor may be, for example, a top-gate or bottom-gate transistor. In addition, the transistor may be a single transistor having one channel forming region. The double gate structure has two gates, while the triple gate structure has three gates. Alternatively, the gate structure may be formed by interposing a gate insulating layer above and below the channel region. The transistor may be a dual-gate type having two gate electrode layers. As an example of a transistor, FIG. 23 shows an example of the structure of a bottom-gate transistor.

[0148] The transistor 510 has a gate electrode layer 512 on a substrate 505. The gate insulating layer 507 is disposed on the gate electrode layer 512. In addition, the oxide semiconductor layer 531 has a source electrode layer and a drain electrode layer (5 15a and 515b) are provided in contact with the island-shaped oxide semiconductor layer 531. , the source electrode layer and the drain electrode layer (515a and 515b) are sandwiched in the contact area. A channel is formed in the oxide semiconductor layer 531 overlapping with the gate electrode layer 512 .

[0149] <Example of transistor manufacturing process> 24A to 24E show examples of cross-sectional structures of transistors. 23.) is a bottom gate transistor 510 similar to the transistor 510 shown in FIG. This is an inverted staggered transistor.

[0150] Hereinafter, a process for manufacturing a transistor 510 on a substrate 505 will be described with reference to FIGS. Explain the process.

[0151] First, a conductive film is formed on a substrate 505 having an insulating surface, and then a first photolithography process is performed. A wiring layer including a gate electrode layer 521 is formed by the process. If the resist is formed by the inkjet method, a photomask is not required. This reduces manufacturing costs.

[0152] In this embodiment mode, a glass substrate is used as the substrate 505 having an insulating surface.

[0153] An insulating film serving as a base film may be provided between the substrate 505 and the gate electrode layer 521. , impurity elements from the substrate 505 (e.g., alkali metals such as Li and Na, and Ca, etc. It has the function of preventing the diffusion of metals such as alkaline earth metals, silicon nitride films, silicon oxide films, etc. A stack of one or more films selected from a silicon oxide nitride film, a silicon oxynitride film, and a silicon nitride film. It can be formed in a layer structure.

[0154] The gate electrode layer 521 may be made of molybdenum, titanium, tantalum, tungsten, or aluminum. Uses metallic materials such as tungsten, copper, neodymium, scandium, etc., or alloy materials whose main components are these. The insulating film may be formed as a single layer or a laminate.

[0155] Next, a gate insulating layer 507 is formed on the gate electrode layer 521. The gate insulating layer 507 is A silicon oxide layer, a silicon nitride layer, etc. are formed by using a plasma CVD method, a sputtering method, etc. , silicon oxynitride layer, silicon nitride oxide layer, aluminum oxide layer, aluminum nitride layer A single layer of aluminum oxide nitride, aluminum oxide nitride, or hafnium oxide is formed. can be formed by laminating.

[0156] The oxide semiconductor of this embodiment is an oxide semiconductor that is made into an i-type or substantially i-type by removing impurities. Such highly purified oxide semiconductors have low interface state density and interface charge Since the interface between the oxide semiconductor layer and the gate insulating layer is extremely sensitive to oxygen, the interface between the oxide semiconductor layer and the gate insulating layer is important. Therefore, the gate insulating layer in contact with the highly purified oxide semiconductor is required to have high quality.

[0157] For example, high-density plasma CVD using microwaves (e.g., 2.45 GHz frequency) produces dense This is preferable because it allows the formation of a high-quality insulating layer with high dielectric strength. The close contact between the gate insulating layer and the high-quality gate insulating layer reduces the interface state density and improves the interface characteristics. This is because it can be made into something that is

[0158] Of course, other film formation methods are also available as long as they can form a good quality insulating layer as a gate insulating layer. In addition, the quality of the gate insulating layer and the oxide semiconductor can be improved by heat treatment after the film formation. In any case, the gate insulating layer may be an insulating layer whose interface characteristics with the body are modified. Not only is the quality of the entire film excellent, but the interface state density with the oxide semiconductor is reduced, resulting in excellent Any material capable of forming a suitable interface may be used.

[0159] In addition, the gate insulating layer 507 and the oxide semiconductor film 530 contain hydrogen, a hydroxyl group, and moisture as much as possible. In order to prevent the oxide semiconductor film 530 from being broken down, sputtering was performed as a pretreatment for the formation of the oxide semiconductor film 530. The substrate 505 on which the gate electrode layer 521 is formed or the gate insulating layer 5 The substrate 505 on which the above-mentioned steps 107 are formed is preheated to remove hydrogen, moisture, etc. adsorbed on the substrate 505. It is preferable to desorb impurities and evacuate them. A pump is preferable. This preheating process can be omitted. Before the insulating layer 516 is formed, the source electrode layer 515a and the drain electrode layer 515b are heated. The same may be done with the formed substrate 505 .

[0160] Next, a film having a thickness of 2 nm to 200 nm, preferably 5 nm or more, is formed on the gate insulating layer 507. An oxide semiconductor film 530 having a thickness of 30 nm or less is formed (see FIG. 24A).

[0161] Note that before the oxide semiconductor film 530 is formed by a sputtering method, argon gas is introduced. The reverse sputtering is performed by introducing the metal into the gate insulating layer 507 to generate plasma. It is preferable to remove the powdery substances (also called particles or dust) that are stuck to the surface. A voltage was applied to the substrate using an RF power supply in an argon atmosphere without applying a voltage to the target side. This method modifies the surface by forming plasma near the substrate by adding argon gas. Alternatively, nitrogen, helium, oxygen, etc. may be used.

[0162] The oxide semiconductor used for the oxide semiconductor film 530 is a quaternary metal oxide, In-S n-Ga-Zn-O oxide semiconductors and In-Ga-Zn-O ternary metal oxides Oxide semiconductors, In-Sn-Zn-O oxide semiconductors, In-Al-Zn-O oxide semiconductors Conductor, Sn-Ga-Zn-O oxide semiconductor, Al-Ga-Zn-O oxide semiconductor, S n-Al-Zn-O oxide semiconductors and In-Zn-O oxides, which are binary metal oxides Semiconductors, Sn-Zn-O oxide semiconductors, Al-Zn-O oxide semiconductors, Zn-Mg- O-based oxide semiconductors, Sn-Mg-O-based oxide semiconductors, In-Mg-O-based oxide semiconductors, I n-Ga-O-based oxide semiconductors, In-O-based oxide semiconductors, which are single-component metal oxides, and Sn -O-based oxide semiconductors, Zn-O-based oxide semiconductors, etc. can be used. The oxide semiconductor layer may contain silicon oxide, which inhibits crystallization. By including SiOx (X>0), the shape of the oxide semiconductor film can be controlled during the manufacturing process. When the film is heated after the synthesis, crystallization can be suppressed. For example, an In-Ga-Zn-O oxide semiconductor is an oxide semiconductor that is made of indium (In), gallium (Ga), It means an oxide film containing zinc (Zn), and the composition ratio is not particularly important. In addition, elements other than In, Ga, and Zn may be included. When using an nO-based material, the composition ratio of the target to be used is In:Zn= 50:1 to 1:2 (converted to molar ratio: In 2 O 3 :ZnO=25:1~1:4), good Preferably, In:Zn=20:1 to 1:1 (in terms of molar ratio, In 2 O 3 :ZnO=1 0:1 to 1:2), and more preferably In:Zn=15:1 to 1.5:1 (in terms of molar ratio) When calculated, it becomes In 2 O 3 For example, In-Zn-O system oxide The target used for forming the compound semiconductor has an atomic ratio of In:Zn:O=X:Y:Z. , Z>1.5X+Y.

[0163] The oxide semiconductor is preferably an oxide semiconductor containing In, more preferably an oxide semiconductor containing In and In order to make the oxide semiconductor layer i-type (intrinsic), In this embodiment, the oxide semiconductor film 530 is formed of In- A film is formed by sputtering using a Ga-Zn-O oxide target. The cross-sectional view at this point corresponds to FIG.

[0164] Examples of targets for forming the oxide semiconductor film 530 by a sputtering method include , the composition ratio is In 2 O 3 :Ga 2 O 3 :ZnO=1:1:1 [molar ratio] oxide Using a target, an In-Ga-Zn-O film is formed. The composition is not limited to, for example, In 2 O 3 :Ga 2 O 3 :ZnO=1:1:2[mol number Ratio], or In 2 O 3 :Ga 2 O 3 ZnO=1:1:4 [molar ratio] Alternatively, an oxide target may be used.

[0165] The filling rate of the oxide target is 90% or more and 100% or less, preferably 95% or more and 99% or less. By using a metal oxide target with a high filling rate, the oxide film formed is The compound semiconductor film can be made dense. The purity of the target is 99.99% or more. The above is preferred, and in particular, alkali metals such as Na and Li and alkaline earth metals such as Ca. It is preferable that the impurities are reduced.

[0166] The oxide semiconductor film 530 is formed using a sputtering gas of hydrogen, water, a hydroxyl group, or a hydrogen atom. It is preferable to use a high-purity gas from which impurities such as oxides have been removed.

[0167] The substrate is held in a film-forming chamber maintained in a reduced pressure state, and the substrate temperature is preferably set to 100° C. or more and 600° C. or less. The temperature is preferably 200° C. or higher and 400° C. or lower. In addition, the concentration of impurities in the oxide semiconductor film can be reduced. Damage caused by etching is reduced. Then, the residual moisture in the deposition chamber is removed using an exhaust pump. While the target is being heated, a sputtering gas from which hydrogen and moisture have been removed is introduced, and the substrate 5 is sputtered using the target. In the deposition chamber, moisture remaining in the deposition chamber and invading from the outside of the deposition chamber are removed. In order to remove hydrogen and moisture that enter the filter (hydrogen and moisture that enter due to leaks), an adsorption type filter is used. Use an empty pump, such as a cryopump, ion pump, or titanium sublimation pump. As for the exhaust means, it is preferable to add a cold trap to the turbo pump. The deposition chamber evacuated using a cryopump may be filled with, for example, hydrogen atoms, Water (H 2 O), etc., which contain hydrogen atoms (and more preferably, compounds containing carbon atoms). Since the gas is exhausted, the concentration of impurities in the oxide semiconductor film formed in the deposition chamber can be reduced. Cut.

[0168] The atmosphere in which the sputtering method is performed is a rare gas (typically argon), oxygen, or a rare gas. The atmosphere may be a mixture of oxygen and oxygen.

[0169] As an example of the film formation conditions, the distance between the substrate and the target is 100 mm, and the pressure is 0.6 Pa. The conditions were: DC power supply 0.5kW, oxygen (oxygen flow rate 100%) atmosphere. In addition, when a pulsed DC power supply is used, the powdery substances (particles, etc.) generated during film formation are reduced. This is preferable because it can reduce the amount of adhesion (also referred to as the "friction") and make the film thickness distribution uniform.

[0170] In addition, the leak rate of the deposition chamber of the sputtering equipment was set to 1×10 -10 Pa·m 3 / second or less By doing so, it is possible to prevent alkali from being added to the oxide semiconductor film during the film formation by the sputtering method. The inclusion of impurities such as metals and hydrides can be reduced.

[0171] In addition, by using an adsorption type vacuum pump as the exhaust system, alkali metals, hydrogen, etc. are removed from the exhaust system. The backflow of impurities such as atoms, hydrogen molecules, water, hydroxyl radicals, or hydrides can be reduced. .

[0172] In addition, alkali metals such as Li and Na and arsenic such as Ca contained in the oxide semiconductor layer It is preferable that impurities such as alkaline earth metals are reduced. The impurity concentrations in the layer were measured using SIMS to determine that Li was 5×10 15 cm -3 Less than or equal to 1×10 15 cm -3 Below, Na is 5 × 10 15 cm -3 The following is preferred: 1×10 15 cm -3 In the following, K is 5×10 15 cm -3 Less than or equal to 1×10 1 5 cm -3 It is preferable that:

[0173] Alkali metals and alkaline earth metals are harmful impurities for oxide semiconductors. In particular, among alkali metals, Na is a metal that is highly likely to cause the insulating film in contact with the oxide semiconductor to become oxide. If so, Na will diffuse into it. + In addition, in the oxide semiconductor, It breaks the oxygen bonds or breaks into the bonds. As a result, the transistor characteristics are deteriorated ( For example, this leads to a normally-on state (a shift of the threshold voltage to the negative side), a decrease in mobility, etc. In addition, this can cause variations in characteristics. Such a problem occurs particularly when hydrogen is present in an oxide semiconductor. This is remarkable when the hydrogen concentration in the oxide semiconductor is sufficiently low. 5×10 19 cm -3 Below, especially 5×10 18 cm -3 If it is below, then it is alkaline. The above metal concentrations are highly desirable.

[0174] Next, the oxide semiconductor film 530 is subjected to a second photolithography process to form an island-shaped oxide semiconductor In addition, a resist for forming an island-shaped oxide semiconductor layer is applied by inkjet printing. If the resist is formed by the inkjet method, a photomask is not required. This reduces manufacturing costs.

[0175] In addition, when a contact hole is formed in the gate insulating layer 507, the process is performed using an oxide semiconductor. This can be done simultaneously with the processing of the membrane 530 .

[0176] Note that the etching of the oxide semiconductor film 530 here may be dry etching or wet etching. For example, the oxide semiconductor film 530 may be subjected to wet etching. The etching solution used for etching is a mixture of phosphoric acid, acetic acid, and nitric acid. Alternatively, ITO07N (manufactured by Kanto Chemical Co., Ltd.) may be used.

[0177] Next, the oxide semiconductor layer is subjected to a first heat treatment. The conductor layer can be dehydrated or dehydrogenated. The temperature of the first heat treatment is 400° C. The temperature is set to 750°C or higher, or 400°C or higher but lower than the distortion point of the substrate. The substrate was placed in an electric furnace, which is one of the equipment used for the deposition of oxide semiconductor layers, and the temperature was raised to 450°C in a nitrogen atmosphere. After the heat treatment for 1 hour, the oxide semiconductor layer was exposed to air and water or moisture was not allowed to enter the oxide semiconductor layer. Thus, an oxide semiconductor layer 531 is obtained (see FIG. 24B).

[0178] The heat treatment device is not limited to an electric furnace, and may be a heat treatment device using heat conduction or heat from a heating element such as a resistance heating element. A device that heats the workpiece by radiation may be used. For example, a GRTA (Gas Reactor Transformer) apid Thermal Annealing) equipment, LRTA (Lamp Rapi) d. Thermal Annealing (RTA) equipment The LRTA device uses a halogen lamp. , metal halide lamps, xenon arc lamps, carbon arc lamps, high pressure sodium The light (electromagnetic waves) emitted from lamps such as mercury lamps and high-pressure mercury lamps The GRTA device is a device that uses high-temperature gas to perform heat treatment. The high temperature gas includes rare gases such as argon, or nitrogen, which are treated by heat treatment. An inert gas that does not react with the chemicals is used.

[0179] For example, the first heat treatment is performed by subjecting the substrate to a base in an inert gas heated to a high temperature of 650° C. to 700° C. The plate is moved and placed in the oven, heated for a few minutes, and then the substrate is moved and placed in an inert gas atmosphere heated to a high temperature. A GRTA may be conducted from the

[0180] In the first heat treatment, nitrogen or a rare gas such as helium, neon, or argon is used. It is preferable that the nitrogen introduced into the heat treatment device does not contain water, hydrogen, etc. Or the purity of rare gases such as helium, neon, and argon must be 6N (99.9999%) or higher. Preferably, the impurity concentration is 7N (99.99999%) or more (i.e., 1 ppm or less, It is preferable that the concentration of the ion exchange resin is 0.1 ppm or less.

[0181] In addition, after the oxide semiconductor layer is heated by the first heat treatment, the oxide semiconductor layer is heated while the heating temperature is maintained or During the process of lowering the temperature from the heating temperature, high-purity oxygen gas and high-purity N 2 O gas, Ultra-dry air (dew point below -40°C, preferably below -60°C) may be introduced. Oxygen Gas or N 2 It is preferable that the O gas does not contain water, hydrogen, etc. Oxygen gas or N introduced into the device 2 The purity of O gas is 6N or more, preferably 7N or more (i.e. , oxygen gas or N 2 The impurity concentration in the O gas is kept at 1 ppm or less, preferably 0.1 ppm or less. It is preferable to use oxygen gas or N 2 Dehydration or dehydrogenation due to the action of O gas The oxide semiconductor that is reduced during the process of removing impurities by chemical treatment By supplying oxygen, which is the main component, the oxide semiconductor layer is highly purified and electrically It becomes type I (true).

[0182] In addition, the first heat treatment of the oxide semiconductor layer is performed on the oxide semiconductor layer before it is processed into the island-shaped oxide semiconductor layer. The semiconductor film 530 may be subjected to the first heat treatment. In that case, the heat treatment device The substrate is then taken out and subjected to a photolithography process.

[0183] In addition to the above, the first heat treatment may be performed after the oxide semiconductor layer is formed. After laminating a source electrode layer and a drain electrode layer on the insulating layer, or This may be performed either after forming an insulating layer on the drain electrode layer or after forming an insulating layer on the drain electrode layer.

[0184] In addition, when a contact hole is formed in the gate insulating layer 507, the process is performed using an oxide semiconductor. This may be done before or after film 530 is subjected to a first heat treatment.

[0185] In addition, the oxide semiconductor layer is formed in two separate steps and heat-treated in two separate steps. Regardless of the material of the component, such as oxide, nitride, or metal, the thick crystalline region, i.e., the film An oxide semiconductor layer having a crystal region in which the c-axis is oriented perpendicular to the surface may be formed. For example, A first oxide semiconductor film having a thickness of 3 nm to 15 nm is formed, and nitrogen, oxygen, a rare gas, or In a dry air atmosphere, 450°C to 850°C, preferably 550°C to 750°C The first heat treatment is performed to obtain a first crystal having a crystalline region (including plate-like crystals) in a region including a surface. Then, a second oxide semiconductor film having a thickness larger than that of the first oxide semiconductor film is formed. The second film is formed at 450° C. or more and 850° C. or less, preferably 600° C. or more and 700° C. or less. heat treatment is performed to grow crystals upward using the first oxide semiconductor film as a seed for crystal growth; The entire second oxide semiconductor film is crystallized to form an oxide semiconductor film having a thick crystalline region. A semiconductor layer may be formed.

[0186] Next, a source electrode layer and a drain electrode layer are formed on the gate insulating layer 507 and the oxide semiconductor layer 531. A conductive film is formed to become the source electrode layer (including wiring formed in the same layer). The conductive film used for the gate electrode layer and the drain electrode layer is, for example, Al, Cr, Cu, Ta, T Metal film containing an element selected from I, Mo, and W, or metal nitride containing the above elements as components It is possible to use a film such as titanium nitride, molybdenum nitride, or tungsten nitride. In addition, Ti, Mo, W, etc. may be applied to either or both of the upper and lower sides of the metal film such as Al or Cu. High melting point metal films or their metal nitride films (titanium nitride film, molybdenum nitride film, titanium nitride film, etc.) In particular, a titanium film and a titanium tin film may be stacked on the side in contact with the oxide semiconductor layer. It is preferable to provide a conductive film containing

[0187] A resist is formed on the conductive film by a third photolithography process, and selective etching is performed. After forming the source electrode layer 515a and the drain electrode layer 515b, the resist is removed. (See FIG. 24(C)).

[0188] In the third photolithography process, ultraviolet light and KrF laser light are used for exposure during resist formation. The source electrode layers adjacent to each other on the oxide semiconductor layer 531 may be irradiated with a laser beam of 100 nm or more. The width of the gap between the end of the drain electrode layer and the bottom end of the drain electrode layer determines the channel width of the transistor to be formed later. When performing exposure with a channel length L of less than 25 nm, the channel length L is determined by the channel length L. Extreme ultraviolet rays have extremely short wavelengths of up to several tens of nanometers. It is preferable to use the ultraviolet light for exposure when forming the resist in the third photolithography process. Line exposure has high resolution and a large depth of focus. It is also possible to set the channel length L to 10 nm or more and 1000 nm or less, and the operating speed of the circuit is The degree can be increased.

[0189] In order to reduce the number of photomasks and steps used in the photolithography process, The resist is formed by a multi-tone mask, which is an exposure mask that allows the light to be exposed to multiple intensities. The etching process may be performed using a multi-tone mask. The shape has a thickness, and the shape can be further changed by etching. Therefore, it can be used in multiple etching processes to process different patterns. A resist that corresponds to at least two different patterns using a single multi-tone mask Therefore, the number of exposure masks can be reduced, and the corresponding photolithography can be performed. The number of lithography steps can also be reduced, making it possible to simplify the process.

[0190] Note that when the conductive film is etched, the oxide semiconductor layer 531 is etched and divided. It is desirable to optimize the etching conditions so as not to cause this. It is difficult to obtain a condition in which the oxide semiconductor layer 531 is etched without being etched at all. During etching of the conductive film, the oxide semiconductor layer 531 is only partially etched, and a groove is formed. In some cases, the oxide semiconductor layer may have a recess (concave portion).

[0191] In this embodiment, a Ti film is used as the conductive film, and an In-Ga- Since a Zn-O-based oxide semiconductor was used, ammonia hydrogen peroxide (NH3H2O) was used as an etchant. A conductive film is selectively etched using a mixture of fluorine, water, and hydrogen peroxide. can be done.

[0192] Next, N 2 O, N 2 Or, plasma treatment using gas such as Ar is performed to remove the exposed Water or the like adsorbed on the surface of the oxide semiconductor layer may be removed by the plasma treatment. In this case, the insulating layer 5, which is a protective insulating film that is in contact with a part of the oxide semiconductor layer without being exposed to the air, is formed. Form 16.

[0193] The insulating layer 516 has a thickness of at least 1 nm. The insulating layer 516 can be formed by using a method that does not mix impurities such as hydrogen. When hydrogen is contained in the oxide semiconductor layer, the hydrogen penetrates into the oxide semiconductor layer, or the hydrogen penetrates into the oxide semiconductor layer. Oxygen in the layer is extracted, and the back channel of the oxide semiconductor layer becomes low-resistance (N-type). Therefore, the insulating layer 516 should be as thin as possible. It is important that the deposition process does not use hydrogen, resulting in a hydrogen-free film.

[0194] In this embodiment, a silicon oxide film having a thickness of 200 nm is formed as the insulating layer 516 by sputtering. The substrate temperature during film formation should be between room temperature and 300°C. In the present embodiment, the temperature is set to 100° C. The silicon oxide film is formed by sputtering using a rare gas (typically In general, under an atmosphere of argon, oxygen, or a mixture of rare gas and oxygen In addition, a silicon oxide target or a silicon target can be used as the target. For example, a silicon target can be used in an oxygen-containing atmosphere. A silicon oxide film can be formed on the oxide semiconductor layer by a sputtering method. The insulating layer 516 to be formed is made of water, hydrogen ions, and OH - It does not contain impurities such as An inorganic insulating film is used to block the intrusion of A silicon oxynitride film, an aluminum oxide film, an aluminum oxynitride film, or the like is used. .

[0195] In the same manner as in the formation of the oxide semiconductor film 530, moisture remaining in the deposition chamber for the insulating layer 516 is removed. For this purpose, it is preferable to use an adsorption type vacuum pump (such as a cryopump). The concentration of impurities contained in the insulating layer 516 formed in a deposition chamber evacuated using an opamp was reduced. In addition, the following exhaust means can be used to remove residual moisture in the deposition chamber for the insulating layer 516: A turbo pump plus a cold trap may also be used.

[0196] The insulating layer 516 is formed using a sputtering gas such as hydrogen, water, a hydroxyl group, or a hydride. It is preferable to use a high-purity gas from which any impurities have been removed.

[0197] Next, a second heat treatment (preferably a second heat treatment) is performed under an inert gas atmosphere or an oxygen gas atmosphere. For example, the heating is performed in a nitrogen atmosphere. The second heat treatment is performed at 250° C. for 1 hour under atmospheric pressure. A portion of the layer (channel formation region) is heated while in contact with the insulating layer 516 .

[0198] Through the above steps, the oxide semiconductor film is subjected to the first heat treatment to remove hydrogen, Impurities such as moisture, a hydroxyl group, or hydride (also called a hydrogen compound) are intentionally removed from the oxide semiconductor layer. The oxide semiconductor is formed by eliminating impurities and reducing the impurity concentration. Therefore, the oxide semiconductor layer can be supplied with oxygen, which is one of the main components of the oxide semiconductor layer. It is purified and electrically made to be type I (intrinsic).

[0199] Through the above steps, the transistor 510 is formed (see FIG. 24D).

[0200] In addition, when a silicon oxide layer containing many defects is used for the insulating layer 516, The heat treatment reduces hydrogen, moisture, a hydroxyl group, hydride, or the like contained in the oxide semiconductor layer. The impurities are diffused into the silicon oxide layer, and the impurities contained in the oxide semiconductor layer are further reduced. This has the effect of making the

[0201] In addition, when a silicon oxide layer containing excess oxygen is used for the insulating layer 516, By this heat treatment, oxygen in the insulating layer 516 moves to the oxide semiconductor layer 531, and the oxide semiconductor layer This improves the oxygen concentration in the layer 531 and provides the effect of increasing the purity.

[0202] A protective insulating layer 506 may be further formed on the insulating layer 516. The protective insulating layer 506 may be, for example, For example, a silicon nitride film is formed by RF sputtering. RF sputtering is suitable for mass production. The protective insulating layer does not contain impurities such as moisture. First, inorganic insulating films are used to block these substances from entering from the outside, and silicon nitride films, In this embodiment mode, a protective insulating film is formed using a silicon nitride film or the like. A layer 506 is formed (see FIG. 24(E)).

[0203] In this embodiment, the substrate 505 on which the insulating layer 516 is formed is used as the protective insulating layer 506. The gas is heated to a temperature of 100℃ to 400℃, and hydrogen and moisture are removed from the gas. A silicon nitride film is formed by introducing a target gas and using a silicon semiconductor target. In this case, similarly to the insulating layer 516, the protective insulating layer 50 is formed while removing the residual moisture in the film formation chamber. It is preferable to deposit 6.

[0204] After the protective insulation layer is formed, it is further heated in air at 100°C to 200°C for 1 hour to 30 hours. This heat treatment may be performed at a constant heating temperature. In addition, the temperature is increased from room temperature to a heating temperature of 100°C or more and 200°C or less, and then decreased from the heating temperature to room temperature. The temperature drop at 0.5° C. may be repeated several times.

[0205] In addition, oxygen doping treatment (oxygen plasma doping treatment) is performed on the oxide semiconductor film 530 and / or The gate insulating layer 507 may be doped with oxygen. This refers to the addition of oxygen (including any of the following: calcium, oxygen atoms, and oxygen ions) to the bulk. The term "bulk" clearly indicates that oxygen is added not only to the surface of the thin film but also to the inside of the thin film. The term "oxygen doping" refers to the addition of oxygen plasma to the bulk. This includes "oxygen plasma doping," which adds

[0206] The oxygen plasma doping process is performed using inductively coupled plasma (ICP). Even if oxygen is added in plasma form using the "Uploaded Plasma" method, , using a microwave with a frequency of 1 GHz or more (for example, a frequency of 2.45 GHz) to create a plasma A method of adding oxygen may also be used.

[0207] The transistor described in this embodiment can achieve high field-effect mobility and therefore can be driven at high speed. Therefore, when a transistor including an oxide semiconductor layer is used in a pixel portion of a liquid crystal display device, By using the oxide semiconductor layer, a high-quality image can be provided. The driver circuit section and pixel section can be fabricated on the same substrate by using a transistor. This makes it possible to reduce the number of parts in the liquid crystal display device.

[0208] Since a transistor including an oxide semiconductor has a low off-state current, By using a semiconductor device, it is possible to reduce problems caused by off-current. This allows for a more accurate display.

[0209] (Embodiment 6) Next, another example of the configuration of the display device and a method of driving the same will be described. In this case, an image that interpolates the movement of an image (input image) input from outside the display device is generated by multiple A display device generates an image based on an input image, and compares the generated image with the input image. The method of displaying the generated image by sequentially adding the motion of the input image will be described. By making the image appear to move in a certain direction, the movement of the video can be made smoother. This improves the problem of image retention and other issues that cause video quality to decrease due to video compensation. The display of moving images ideally requires changing the brightness of each pixel in real time. This is achieved by controlling the pixels in real time, but the real-time individual control of the pixels is The number of paths becomes huge, the wiring space becomes an issue, and the amount of input image data becomes huge. Therefore, it is difficult to realize the display of moving images on a display device. The display is made to look like a moving image by displaying multiple still images in sequence at a regular interval. This period (called the input image signal period in this embodiment, T in and For example, the NTSC standard is 1 / 60th of a second, and the PAL standard is 1 Even with this period, the impulse type display device, the CRT, is not affected by the movement. However, there were no problems with the image display. If a video conforming to the above is displayed as is, the display may be blurred due to afterimages caused by the hold type. This causes a problem called hold blur. Blurring occurs when the human eye compensates for unconscious movements and the display does not match the hold type. Since it is recognized by discrepancy, the input image signal is smaller than that of the conventional standard. This can be reduced by shortening the signal cycle (approaching real-time individual control of pixels). However, shortening the input image signal period will require changes to the standard and will also increase the amount of data. However, it is difficult to do this based on a standardized input image signal. An image that interpolates the movement of the input image is generated inside the display device, and the generated image By interpolating the input image and displaying it, the hold function can be used without changing the standard or increasing the amount of data. In this way, the image signal is generated inside the display device based on the input image signal. The process of interpolating the motion of an input image is called video interpolation.

[0210] The moving image interpolation method according to the present embodiment can reduce the blurring of the moving image. The moving image interpolation method in the embodiment can be divided into an image generation method and an image display method. And for certain patterns of movement, different image generation methods and / or image display methods are used. By using this method, motion blur can be effectively reduced. FIG. 1B is a schematic diagram for explaining an example of a moving image interpolation method according to the present embodiment. In Fig. 25(A) and (B), the horizontal axis is time, and the horizontal position indicates The part marked "Input" indicates the timing at which each image is handled. This represents the timing at which two images are input. The image 5121 and the image 5122 are focused on. The input image has a period T in Enter at intervals of In addition, the period T in The length of one frame is referred to as one frame period. The part marked "Generation" indicates the timing at which a new image is generated from the input image signal. Here, the generated image is based on the image 5121 and the image 5122. The part marked "display" indicates that the image is displayed on the display device. This shows the timing when the image is displayed. Although it is only indicated by a dashed line, by treating it in the same way as the image of interest, An example of a method for interpolating moving images in this form can be realized.

[0211] In the present embodiment, an example of a method for interpolating a moving image is shown in FIG. A generated image is generated based on two adjacent input images. The two input images are displayed. By displaying the video in the gap between the two, it is possible to interpolate the video. It is preferable that the display period of the display image is half the input period of the input image. However, The display period is not limited to this, and various display periods can be used. For example, the display period is set to the input period. By making it shorter than 1 / 2, the video can be displayed more smoothly. By making the period longer than half, power consumption can be reduced. The image is generated based on two input images, but the input images are limited to two. Various numbers can be used, for example, three (or more than three) adjacent in time. If an image is generated based on the first input image, the accuracy will be higher than if it is generated based on two input images. It is to be noted that the display timing of the image 5121 is set to be the same as that of the image 5 The same time as the input timing of 122, that is, the display timing for the input timing is 1 Although it is a frame delay, the display timing in the video interpolation method of this embodiment is The timing is not limited to this, and various display timings can be used. For example, You can delay the display timing for the sync by one or more frames. Since the display timing of the generated image 5123 can be delayed, the image 51 This allows for more time for the generation of 23, reducing power consumption and manufacturing costs. If the display timing is too delayed relative to the input timing, The image storage period will be longer, and the memory capacity required for storage will increase. The display timing relative to the input timing is preferably delayed by about one to two frames. It is nice.

[0212] Here, the specific image 5123 generated based on the image 5121 and the image 5122 is In order to interpolate a moving image, the motion of the input image is detected. However, in this embodiment, a block map is used to detect the motion of the input image. However, there are various methods that can be used without being limited to this. (Methods such as taking the difference between image data and using Fourier transform) can be used. In the block matching method, first, the image data of one input image (here, the image 5121) to a data storage means (semiconductor memory, RAM or other storage circuit, etc.) Then, the image in the next frame (image 5122 in this example) is stored in memory. The divided areas are all rectangular in shape, as shown in Figure 25(A). It can be, but is not limited to, various things (shape or size can be changed depending on the image) Then, for each divided area, the data stored in the data storage means can be The data is compared with the image data of the previous frame (here, the image data of image 5121). In the example of FIG. 25(A), the image 5122 has similar image data. A region similar in data to the region 5124 in the image 5121 is searched for, and the region 512 6 is assumed to have been searched. Note that when searching within image 5121, the search range is limited. In the example of FIG. 25(A), the search range is preferably set to an area 5124. The area 5125 is set to be about four times the area of ​​the By making it larger, the detection accuracy can be improved even in fast-moving videos. However, if the search is too broad, the search time will be enormous, and the detection of motion will be difficult. Since this would be difficult to realize, the area of ​​the region 5125 is set to about 2 to 6 times the area of ​​the region 5124. Then, the searched region 5126 and the region in the image 5122 are compared. The difference in position between the area 5124 and the motion vector 5127 is calculated. 7 represents the movement of image data in the region 5124 during one frame period. To generate an image that represents an intermediate state of motion, the motion vectors are scaled while keeping their orientation unchanged. A modified image generation vector 5128 is created, and the region 5126 in the image 5121 is The image data is moved according to the image generation vector 5128 to generate the image 5123. This series of processing is called image 512 By performing this for all regions in 2, an image 5123 is generated. Then, the image By sequentially displaying image 5121, image 5123, and image 5122, a video can be interpolated. Note that the position of the object 5130 in the image is different in the image 5121 and the image 5122. Although different (i.e. moving), the generated image 5123 is similar to the images 5121 and This is the midpoint of the object in image 5122. By displaying such an image, This makes it possible to make the movement of images smoother and improves blurring of moving images caused by afterimages, etc.

[0213] The size of the image generation vector 5128 is determined according to the display timing of the image 5123. In the example of FIG. 25(A), the display timing of the image 5123 can be determined as follows: Since the timing is set to the midpoint (1 / 2) of the display timing of the image 5121 and the image 5122, The size of the image generation vector 5128 is half that of the motion vector 5127. For example, if the display timing is 1 / 3, the size is set to 1 / 3. If the staging is at 2 / 3, the size can be set to 2 / 3.

[0214] In this way, multiple regions with various motion vectors are moved to create a new image. When creating an image, the area to be moved may contain overlapping areas, or it may be possible to move the area to another area. There may be some blank areas that are not moved from the area. As a method for correcting the overlapping portion, for example, Priority is assigned based on the average method, the direction of the motion vector, etc., and data with high priority is generated. The method of making the data in the generated image, where either color (or brightness) is given priority, but brightness (or For example, the method of taking the average of the number of pixels (or color) can be used. The image data at the corresponding position of the image 5121 or 5122 is directly used as the data in the generated image. A method for obtaining the average of image data at the corresponding position of the image 5121 or the image 5122. Then, the generated image 5123 can be used as a method for generating an image. By displaying the vector 5128 at a timing that matches its size, the movement of the video becomes smoother. Furthermore, the problem of image retention caused by hold drive resulting in reduced video quality can be eliminated. You can improve the problem.

[0215] Another example of the moving image interpolation method according to the present embodiment is a time interpolation method as shown in FIG. A generated image is generated based on two input images that are adjacent to each other. When displaying the images in the gaps between the displayed images, each image is further divided into multiple sub-images. By dividing the image into several parts and displaying them, it is possible to perform video interpolation. In addition to the benefits of shorter time, dark images are periodically displayed (the display method is This also provides the advantage of the image display period being closer to the image input period. This reduces blurring of the video due to afterimages, etc., compared to when the length is only half that of the power cycle. In the example of FIG. 25(B), the input and generation are 5(A) can be performed, so the explanation will be omitted. In the example, "display" means splitting one input image and / or generated image into multiple sub-images. Specifically, as shown in FIG. 25(B), an image 5121 can be displayed. By dividing the image into sub-images 5121a and 5121b and displaying them in sequence, The subject is made to perceive the image 5121 as being displayed, and the image 5123 is made to appear as sub-images 5123a and 5123b. By dividing the image into sub-images 5123a and 5123b and displaying them sequentially, the image 5123 appears to the human eye. The image 5122 is divided into sub-images 5122a and 5122b. By dividing and displaying the images sequentially, the human eye perceives the image 5122 as being displayed. That is, while the image perceived by the human eye is similar to the example in FIG. The display method can be made closer to the impulse type, which can reduce blurring of moving images caused by afterimages, etc. This can be further improved. Note that the number of sub-image divisions is set to two in FIG. 25(B). However, the number of divisions is not limited to this and various division numbers can be used. In FIG. 25(B), the timing is set to equal intervals (1 / 2), but this is not limited to this. Various display timings can be used without any problem. For example, the dark sub-image (5121b, 5 122b, 5123b) to be displayed earlier (specifically, from 1 / 4 to 1 / 2) By using the timing function, the display method can be made closer to the impulse type, so there is no afterimage. This can further improve the blurring of moving images caused by the dark sub-image. By shortening the time for displaying a bright image (specifically, from 1 / 2 to 3 / 4), Since the length can be increased, the display efficiency can be improved and power consumption can be reduced.

[0216] Another example of the moving image interpolation method according to the present embodiment is to detect the shape of an object moving in an image. This is an example in which different processing is performed depending on the shape of the moving object. indicates the timing of display in the same way as the example in FIG. 25(B), but the displayed content is This shows the case of moving text (also called scrolling text, subtitles, telop, etc.). In addition, the "input" and "generation" may be the same as those in FIG. 25(B). The blurring of moving images during hold driving is due to the nature of the moving object. This is especially noticeable when the text is moving. This is because when reading moving text, your eyes will inevitably follow the text. This is because hold blurring is likely to occur. Furthermore, characters have clear outlines. This can further accentuate the blur caused by hold blur. That is, it is necessary to determine whether an object moving in an image is a character or not, and if so, to perform further special processing. This is effective for reducing hold blur. Contour and / or pattern detection is performed on the object to determine whether the object is a character. If it is determined that there is a motion, motion compensation is not performed even if the sub-images are divided from the same image. By displaying intermediate states of the object's movement, the object's movement can be made smoother. If it is determined that the character is not a character, the image is divided into two parts, as shown in Fig. 25(B). If the sub-image is a moving one, the position of the moving object can be displayed without changing. In the example shown in FIG. 1, an area 5131 determined to be a character is moving upward. However, the position of the region 5131 is different between the sub-image 5121a and the sub-image 5121b. Sub-image 5123a and sub-image 5123b, sub-image 5122a and sub-image 51 The same is true for 22b. This makes it possible to reduce the blurring caused by the hold effect. For text, this makes the movement even smoother than with normal motion compensation double speed drive. Therefore, blurring of moving images caused by afterimages or the like can be further improved.

[0217] (Embodiment 7) In this embodiment, examples of electronic devices will be described. 27(A) to 27(D) are diagrams showing electronic devices. These electronic devices include: Housing 5000, display unit 5001, speaker 5003, LED lamp 5004, operation key 5 005 (including a power switch or an operation switch), a connection terminal 5006, and a sensor 5007 (force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemicals quality, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, (including a function to measure light or infrared rays), microphone 5008, etc. can be done.

[0218] FIG. 26(A) shows a mobile computer, which includes, in addition to the above, a switch 5009, The portable terminal 5010 may have an infrared port 5010. A type of image reproducing device (for example, a DVD reproducing device) that, in addition to the above, also has a second display 26C shows a goog In addition to the above, the display includes a second display unit 5002, a support unit 5012, The game machine may have earphones 5013, etc. FIG. 26(D) shows a portable game machine. In addition to the above, the device may have a recording medium reading unit 5011, etc. In addition to the above, the projector includes a light source 5033, a projection lens 5034, etc. FIG. 26(F) shows a portable gaming machine, which, in addition to the above, has a second display unit. 26(G) shows a television receiver. In addition to the above, the image sensor may also include a tuner, an image processor, etc. 26(H) is a portable television receiver, capable of transmitting and receiving signals in addition to the above. FIG. 27(A) shows a display, and the above-mentioned In addition to the above, a support stand 5018 and the like can be provided. FIG. 27(B) shows a camera. In addition to the above, an external connection port 5019, a shutter button 5015, an image receiving unit 5016, etc. FIG. 27(C) is a computer, In addition, there is a pointing device 5020, an external connection port 5019, a reader / writer 5 021, etc. FIG. 27(D) shows a mobile phone, which can have the above-mentioned In addition, an antenna 5014, a 1-segment partial reception service tuner for mobile phones and mobile terminals It may have a nozzle, etc.

[0219] The electronic devices shown in FIGS. 26(A) to 26(H) and 27(A) to 27(D) are For example, various information (still images, videos, text images, etc.) Function to display on the display unit, touch panel function, calendar, date or time display, etc. Functions, functions to control processing by various software (programs), wireless communication functions, A function to connect to various computer networks using wireless communication functions, A function to transmit or receive various data using a program recorded on a recording medium The data can be read out and displayed on the display unit. In electronic devices with displays, one display unit is used primarily to display image information, and another A function that mainly displays text information on one display unit, or a function that takes parallax into account on multiple displays By displaying an image, it is possible to have a function of displaying a stereoscopic image. In electronic devices having an image receiving unit, the functions of taking still images, taking videos, and The function to automatically or manually correct the captured image, and to store the captured image on a recording medium (external or in the camera) It can have functions such as storing the captured image on a built-in memory and displaying the captured image on the display unit. Note that the electronic devices shown in FIGS. The functions that can be possessed by the are not limited to these, and the function can have various functions.

[0220] The electronic device described in this embodiment has a display unit for displaying some information. Such an electronic device is characterized in that it has an oxide semiconductor with low off-state current. By using transistors to configure a circuit, unnecessary current leaks in. This prevents the circuit from malfunctioning and allows for accurate display. do.

[0221] In addition, thin-film transistors that have an I-type (intrinsic) oxide semiconductor layer in the active layer have a low off-current. The oxide semiconductor layer is particularly preferably made to be an i-type (intrinsic) oxide semiconductor layer. , dehydration or dehydrogenation is effective.

[0222] Next, application examples of the semiconductor device will be described.

[0223] FIG. 27(E) shows an example in which a semiconductor device is integrated with a building. ) includes a housing 5022, a display unit 5023, a remote control device 5024 as an operation unit, and a speaker 5025. The semiconductor device is a wall-mounted type that is integrated with the building and requires a large space to install. It can be installed without requiring a large space.

[0224] FIG. 27(F) shows another example in which a semiconductor device is provided inside a building as an integral part of the building. The display panel 5026 is attached to the unit bath 5027 and is The display panel 5026 becomes viewable.

[0225] In this embodiment, a wall and a unit bath are used as examples of structures. The manner in which the semiconductor device is installed is not limited to this, and the semiconductor device can be installed in various structures.

[0226] Next, an example in which the semiconductor device is integrated with a moving object will be described.

[0227] FIG. 27G is a diagram showing an example in which the semiconductor device is provided in an automobile. 5028 is attached to a vehicle body 5029 of a vehicle, and is configured to detect the movement of the vehicle body or the inside and outside of the vehicle. The information entered can be displayed on demand. It is okay to do so.

[0228] FIG. 27(H) is a diagram showing an example in which a semiconductor device is integrated with a passenger airplane. FIG. 27(H) shows a passenger plane with a display panel 5031 on a ceiling 5030 above the seats. The display panel 5031 is attached to the ceiling 50. 30 and the hinge portion 5032. This allows passengers to view the display panel 5031. The display panel 5031 is operated by passengers. It has the function of displaying information by

[0229] In this embodiment, an automobile body and an airplane body are exemplified as moving bodies. However, this is not limited to motorcycles, four-wheeled vehicles (including cars, buses, etc.), trains (monorail, etc.) They can be installed on a variety of things, including buildings, railways, ships, etc.

[0230] Since a transistor including an oxide semiconductor has a low off-state current, By using a semiconductor device, it is possible to reduce problems caused by off-current. This allows for a more accurate display.

[0231] In addition, thin-film transistors that have an I-type (intrinsic) oxide semiconductor layer in the active layer have a low off-current. The oxide semiconductor layer is particularly preferably made to be an i-type (intrinsic) oxide semiconductor layer. , dehydration or dehydrogenation is effective. [Explanation of symbols]

[0232] 100 pixels 100a pixels 100b pixels 100c pixels 101a Transistor 101b Transistor 101c Transistor 102a Display element 102b Display element 102c Display element 103a Capacitive element 103b Capacitive element 103c Capacitive element 104a Wiring 104b Wiring 104c Wiring 105a Wiring 105b Wiring 106a Wiring 106b Wiring 106c Wiring 107a Wiring 107b Wiring 107c Wiring 501 Transistor 501b Transistor 501c transistor 502 Circuit 503 Capacitive element 503b Capacitive element 503c Capacitive element 504 Circuit 505 Board 506 Protective insulation layer 507 Gate Insulation Layer 510 Transistor 511 Substrate 512 Gate electrode layer 513 Circuit 515a Source electrode layer 515b Drain electrode layer 516 Insulating Layer 530 Oxide Semiconductor Film 531 Oxide Semiconductor Layer 801 Pixel section 901 Transistor 901b Transistor 901c Transistor 903 Capacitive element 903b Capacitive element 903c Capacitive element 904 Wiring 904b Wiring 904c Wiring 906 Wiring 906b Wiring 906c Wiring 913 Capacitor 913b Capacitive element 913c Capacitive element 5000 cabinet 5001 Display section 5002 Display section 5003 Speaker 5004 LED Lamp 5005 Operation key 5006 Connection terminal 5007 Sensor 5008 Microphone 5009 Switch 5010 Infrared port 5011 Recording medium reading unit 5012 Support part 5013 Earphones 5014 Antenna 5015 Shutter button 5016 Image receiving unit 5017 charger 5018 Support stand 5019 External connection port 5020 Pointing Device 5021 Reader / Writer 5022 Case 5023 Display section 5024 Remote control device 5025 Speaker 5026 Display Panel 5027 Unit Bath 5028 Display Panel 5029 Body 5030 Ceiling 5031 Display Panel 5032 Hinge part 5033 Light source 5034 Projection Lens 5121 images 5121a Sub image 5121b Images 5122 images 5122a Sub image 5122b Sub-image 5123 images 5123a Sub image 5123b Sub-image 5124 area 5125 area 5126 area 5127 Vector 5128 Image Generation Vectors 5129 area 5130 Object 5131 area

Claims

1. A pixel includes a first subpixel, a second subpixel, and a third subpixel, the first subpixel to the third subpixel are arranged in a column direction, the first subpixel includes a first transistor; the second subpixel includes a second transistor; the third subpixel includes a third transistor; one of the source and the drain of the first transistor is always electrically connected to a first source wiring; a gate of the first transistor is always electrically connected to a first gate signal line; one of the source and the drain of the second transistor is always electrically connected to a second source wiring; a gate of the second transistor is always electrically connected to the first gate signal line; one of the source and the drain of the third transistor is always electrically connected to a third source wiring; a gate of the third transistor is always electrically connected to the first gate signal line; a channel length of the first transistor is approximately equal to a channel length of the second transistor; A display device, wherein a channel length of the first transistor is approximately equal to a channel length of the third transistor.

2. A pixel includes a first subpixel, a second subpixel, and a third subpixel, the first subpixel to the third subpixel are arranged in a column direction, the first subpixel includes a first transistor; the second subpixel includes a second transistor; the third subpixel includes a third transistor; one of the source and the drain of the first transistor is always electrically connected to a first source wiring; a gate of the first transistor is always electrically connected to a first gate signal line; one of the source and the drain of the second transistor is always electrically connected to a second source wiring; a gate of the second transistor is always electrically connected to the first gate signal line; one of the source and the drain of the third transistor is always electrically connected to a third source wiring; a gate of the third transistor is always electrically connected to the first gate signal line; a ratio of a channel width to a channel length of the first transistor is approximately equal to a ratio of a channel width to a channel length of the second transistor; A display device, wherein a ratio of a channel width to a channel length of the first transistor is approximately equal to a ratio of a channel width to a channel length of the third transistor.

3. In claim 1 or 2, the first transistor includes an oxide semiconductor layer having a channel formation region, the oxide semiconductor layer has a region sandwiched between a first insulating layer and a second insulating layer; the second insulating layer has a region located on the oxide semiconductor layer, the first insulating layer comprises oxygen and silicon; The second insulating layer comprises nitrogen and silicon.

4. In any one of claims 1 to 3, the first transistor includes a first conductive layer having a region functioning as a source electrode and a second conductive layer having a region functioning as a drain electrode; The display device, wherein the first conductive layer and the second conductive layer contain Ti and Cu.

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