Light emitting device

Abstract

To provide a capacitive element having a large capacitance per occupied area. A semiconductor device including the capacitor is provided. A highly integrated semiconductor device is provided. A novel semiconductor device is provided. A high-definition display device is provided. A display device with stable display quality is provided.SOLUTION: The semiconductor device includes a first conductive film and a second conductive film over an insulating surface, a first insulating film over the insulating surface, the first conductive film, and the second conductive film, a semiconductor film overlapping with the first conductive film with the first insulating film positioned therebetween, a third conductive film in contact with the semiconductor film, and a fourth conductive film in contact with the semiconductor film and overlapping with the second conductive film with the first insulating film positioned therebetween. The semiconductor device includes a second insulating film having a thick region and a thin region, a fifth conductive film overlapping with the semiconductor film with the second insulating film provided therebetween, and a sixth conductive film overlapping with the fourth conductive film in the thin region of the second insulating film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, relating to the manufacture or composition of matter, especially The present invention relates to, for example, a semiconductor device, a display device, a liquid crystal display device, an electroluminescence (EL: Electroluminescence) display devices, light-emitting devices, lighting devices, or a semiconductor film, a semiconductor device, a display device, a light-emitting device, a lighting device, a The present invention relates to a method for manufacturing a lighting device, a power storage device, a memory device, and a processor. The present invention relates to a display device, a light-emitting device, a lighting device, a power storage device, a storage device, and a method for driving a processor. One embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a memory device, or the like, which includes a transistor. Alternatively, one aspect of the present invention relates to a device, a processor, or a driving method thereof. The semiconductor device, the display device, the light-emitting device, the storage device, or the processor This relates to electronic devices, etc.

[0002] In this specification, a semiconductor device is a device that can function by utilizing semiconductor characteristics. Display devices, light-emitting devices, electro-optical devices, semiconductor circuits, and electronic devices are all semiconductor devices. It may have a conductor device. [Background technology]

[0003] A technology for constructing a transistor using a semiconductor film formed on a substrate with an insulating surface is The transistor is widely used in semiconductor devices such as integrated circuits and display devices. It has been done.

[0004] The semiconductor film used in the transistor is an amorphous silicon film, a polycrystalline silicon film, an oxide semiconductor film, etc. For example, the transistors that make up large display devices The substrate is made of amorphous silicon or oxide semiconductor, for which film formation technology on large-area substrates has been established. On the other hand, a highly functional display device in which a driving circuit is integrally formed is constructed. The transistor is made of polycrystalline silicon, which allows the fabrication of transistors with high field-effect mobility. A silicon film or an oxide semiconductor film is preferably used.

[0005] In recent years, the resolution of portable information terminals has increased, and the area per pixel has decreased. As the area shrinks, the proportion of wiring, transistors, and capacitors in a pixel increases. To reduce the wiring area, it is effective to use low-resistance copper wiring, for example. In order to reduce the area of ​​the transistor, for example, It is effective to use a polycrystalline silicon film or an oxide semiconductor film.

[0006] Patent Document 1 describes a transistor using an oxide semiconductor film and a capacitor using an oxide semiconductor film. A display device having the element is disclosed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2011 / 148537 Summary of the Invention [Problem to be solved by the invention]

[0008] It is an object of the present invention to provide a capacitor element having a large capacitance per occupied area. It is an object of the present invention to provide a semiconductor device having a capacitor. It is an object of the present invention to provide a semiconductor device. This is one of the challenges.

[0009] Another object is to provide a high-definition display device. An object of the present invention is to provide a display device having

[0010] The description of these problems does not preclude the existence of other problems. It is not necessary for the present invention to solve all of these problems. The above will be made clear from the description, drawings, claims, etc. It is possible to extract other issues from the descriptions in the patent, claims, etc. [Means for solving the problem]

[0011] One aspect of the present invention is described below.

[0012] (1) A first conductive film and a second conductive film on an insulating surface, and a second conductive film on the insulating surface, the first conductive film, and and a first insulating film on the second conductive film, and a semiconductor layer overlapping the first conductive film through the first insulating film. a third conductive film in contact with the semiconductor film; a second conductive film in contact with the semiconductor film and through a first insulating film; a fourth conductive film overlapping the first conductive film, and a second conductive film on the semiconductor film, the third conductive film, and the fourth conductive film; a second insulating film having a thick region and a thin region; and a semiconductor film interposed between the second insulating film and the semiconductor film. a fifth conductive film overlapping the fourth conductive film in a thin region of the second insulating film; and a sixth conductive film overlapping the fourth conductive film in a thin region of the second insulating film. and a semiconductor device having the above.

[0013] (2) A first conductive film and a second conductive film on an insulating surface, and a second conductive film on the insulating surface, the first conductive film and a first insulating film on the first and second conductive films, the first insulating film having a thick region and a thin region; a semiconductor film overlapping the first conductive film with a third conductive film in contact with the semiconductor film; a fourth conductive film that is in contact with the semiconductor film and overlaps the second conductive film in a thin region of the first insulating film; a second insulating film on the third conductive film and the fourth conductive film, and a semiconductor film via the second insulating film; a fifth conductive film overlapping the fourth conductive film via the second insulating film; and a sixth conductive film overlapping the fourth conductive film via the second insulating film. The semiconductor device has the following.

[0014] (3) A first conductive film and a second conductive film on an insulating surface, and a second conductive film on the insulating surface, the first conductive film, and a first insulating film on the first and second conductive films, the first insulating film having a thick region and a thin region; a semiconductor film overlapping the first conductive film with a third conductive film in contact with the semiconductor film; a fourth conductive film that is in contact with the semiconductor film and overlaps the second conductive film in a thin region of the first insulating film; a second insulating film on the third conductive film and the fourth conductive film, the second insulating film having a thick region and a thin region; a fifth conductive film overlapping the semiconductor film via a second insulating film; and a thin region of the second insulating film. and a sixth conductive film overlapping the fourth conductive film in the region.

[0015] (4) The semiconductor device according to any one of (1) to (3), wherein the semiconductor film is an oxide semiconductor film. It is a location.

[0016] (5) The semiconductor according to any one of (1) to (3), wherein the semiconductor film is a polycrystalline silicon film. It is a device.

[0017] (6) a third insulating film on the second insulating film, the fifth conductive film, and the sixth conductive film; A display element is provided on the insulating film and is electrically connected to the fourth conductive film. 5) is a semiconductor device according to any one of the above. [Effects of the Invention]

[0018] It is possible to provide a capacitive element having a large capacitance per occupied area. Alternatively, a semiconductor device having a high degree of integration can be provided. Alternatively, a novel semiconductor device can be provided. The present invention is not limited to these effects. For example, one embodiment of the present invention may have the following effects: Depending on the situation, it may have other effects. For example, one embodiment of the present invention may have these effects in some cases or depending on the situation. Sometimes it doesn't exist.

[0019] Alternatively, a high-definition display device can be provided. Alternatively, a display device having stable display quality can be provided. A display device can be provided. [Brief explanation of the drawings]

[0020] [Figure 1] 1A and 1B are a cross-sectional view and a circuit diagram illustrating an example of a capacitor according to one embodiment of the present invention. [Figure 2] 1A to 1C are a circuit diagram, a top view, and a cross-sectional view illustrating an example of a display device according to one embodiment of the present invention. [Figure 3] FIG. 1 is a cross-sectional view illustrating an example of a display device according to one embodiment of the present invention. [Figure 4] FIG. 1 is a cross-sectional view illustrating an example of a display device according to one embodiment of the present invention. [Figure 5] 1A and 1B are a circuit diagram and a cross-sectional view illustrating an example of a display device according to one embodiment of the present invention. [Figure 6] 1A to 1C are a circuit diagram, a top view, and a cross-sectional view illustrating an example of a display device according to one embodiment of the present invention. [Figure 7] 10A and 10B are a timing chart and a circuit diagram illustrating threshold voltage correction in a pixel of a display device according to one embodiment of the present invention. [Figure 8] FIG. 10 is a circuit diagram illustrating threshold voltage correction in a pixel of a display device according to one embodiment of the present invention. [Figure 9] 1A and 1B are a top view and a cross-sectional view illustrating an example of a manufacturing method of a display device according to one embodiment of the present invention. [Figure 10] 1A and 1B are a top view and a cross-sectional view illustrating an example of a manufacturing method of a display device according to one embodiment of the present invention. [Figure 11] 1A and 1B are a top view and a cross-sectional view illustrating an example of a manufacturing method of a display device according to one embodiment of the present invention. [Figure 12] 1A and 1B are a top view and a cross-sectional view illustrating an example of a manufacturing method of a display device according to one embodiment of the present invention. [Figure 13] 1A and 1B are a top view and a cross-sectional view illustrating an example of a manufacturing method of a display device according to one embodiment of the present invention. [Figure 14] 1A and 1B are a top view and a cross-sectional view illustrating an example of a manufacturing method of a display device according to one embodiment of the present invention. [Figure 15] 1A and 1B are a top view and a cross-sectional view illustrating an example of a manufacturing method of a display device according to one embodiment of the present invention. [Figure 16] 1A and 1B are a top view and a cross-sectional view illustrating an example of a manufacturing method of a display device according to one embodiment of the present invention. [Figure 17] 10A and 10B are graphs showing threshold voltage correction capabilities of a display device according to one embodiment of the present invention. [Figure 18] 1A and 1B illustrate a display module according to one embodiment of the present invention. [Figure 19] 1A to 1C illustrate examples of electronic devices and lighting devices according to one embodiment of the present invention. [Figure 20] 1A to 1C illustrate examples of electronic devices according to one embodiment of the present invention. [Figure 21] 1 is a photograph of a display device according to one embodiment of the present invention. [Figure 22] FIG. 10 is a circuit diagram of a scan line driver circuit according to one embodiment of the present invention. [Figure 23] FIG. 2 is a diagram showing the connection relationship of a scanning line driving circuit. [Figure 24]FIG. 1 is a circuit diagram of a shift register according to one embodiment of the present invention. [Figure 25] FIG. 1 is a circuit diagram of a shift register according to one embodiment of the present invention. [Figure 26] FIG. 1 is a circuit diagram of a shift register according to one embodiment of the present invention. [Figure 27] FIG. 1 is a circuit diagram of a shift register according to one embodiment of the present invention. [Figure 28] FIG. 1 is a circuit diagram of an inverter according to one embodiment of the present invention. [Figure 29] 10 is a timing chart of a scan line driver circuit according to one embodiment of the present invention. [Figure 30] 10A and 10B are diagrams showing output waveforms of a scan line driver circuit according to one embodiment of the present invention. [Figure 31] FIG. 2 is a diagram showing color coordinates of each of RGB colors of a display device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above, and various modifications in form and details can be easily made by those skilled in the art. It is understood that the present invention should not be construed as being limited to the description of the following embodiments. In explaining the configuration of the invention using the drawings, the same reference numerals are used to refer to the same parts. The hatch pattern is used in common between drawings. However, there are cases where no particular symbol is attached.

[0022] The content of one embodiment may be applied to or combined with the content of another embodiment. Alternatively, a replacement or the like can be performed.

[0023] It should be noted that in the drawings, the size, layer thickness, or area may be exaggerated for clarity. Therefore, it is not necessarily limited to that scale.

[0024] Also, voltage is a voltage between a certain potential and a reference potential (for example, ground potential (GND) or source potential). Therefore, voltage can be replaced with potential. .

[0025] In this specification, even when the expression "electrically connect" is used, it does not mean that the actual circuit In some cases, there may be no physical connection and only wires running.

[0026] The ordinal numbers such as 1st and 2nd are used for convenience and do not indicate the order of the processes or the order of stacking. Therefore, for example, "the first" should not be replaced with "the second" or "the third" In addition, the ordinal numbers described in this specification and the like can be replaced with the following. The ordinal numbers used to identify aspects of the present invention may not be consistent.

[0027] In this specification, the shape of an object may be referred to as, for example, a "diameter," a "particle size," a "size," a "diameter ... When specifying "width" etc., it is the length of one side of the smallest cube that the object can fit into, or the length of the object. The equivalent diameter of a circle in a cross section of an object may be read as the diameter of a circle in a cross section of the object. The diameter of a circle with an area equal to the cross section of the body.

[0028] Even when written as "semiconductor," if the conductivity is sufficiently low, it may be written as "insulator." In addition, the boundary between "semiconductor" and "insulator" is vague, and Therefore, the term "semiconductor" as used herein may be used interchangeably with "insulator." Similarly, the term "insulator" used herein can be interpreted as "semiconductor." " can sometimes be rephrased as ".

[0029] Also, even if a material is written as a "semiconductor," if the material has a sufficiently high conductivity, it may be written as a "conductor." In addition, the boundary between "semiconductor" and "conductor" is vague, and Therefore, the term "semiconductor" as used herein may be used interchangeably with "conductor." Similarly, the term "conductor" used in this specification can be used to refer to a "semiconductor." " can sometimes be rephrased as ".

[0030] The impurities in the semiconductor film refer to, for example, substances other than the main components constituting the semiconductor film. For example, Elements with a concentration of less than 0.1 atomic% are impurities. For example, carrier traps may be formed in the semiconductor film, and carrier mobility may decrease. If the semiconductor film is an oxide semiconductor film, the crystallinity may be reduced. In this case, impurities that change the properties of the semiconductor film include, for example, Group 1 elements, Group 2 elements, There are elements of Group 14, Group 15, transition metals other than the main component, etc., especially, for example, hydrogen ( (Also found in water), lithium, sodium, silicon, boron, phosphorus, carbon, nitrogen, etc. In the case of an oxide semiconductor, oxygen vacancies may be formed due to the inclusion of impurities. When the semiconductor film is a silicon film, impurities that change the properties of the semiconductor film include, for example, Examples include oxygen, Group 1 elements excluding hydrogen, Group 2 elements, Group 13 elements, and Group 15 elements. .

[0031] In this specification, the term "excess oxygen" refers to, for example, oxygen contained in excess of the stoichiometric composition. Alternatively, excess oxygen refers to oxygen released by heating, for example. For example, oxygen can move inside the film or layer. The movement of excess oxygen can cause the atoms of the film or layer to move. When oxygen moves between membranes and layers, it moves in a chain reaction, replacing oxygen that makes up the membranes and layers. In addition, an insulating film containing excess oxygen has a function of releasing oxygen by, for example, heat treatment. It is an insulating film with excellent properties.

[0032] In this specification, "parallel" means that two straight lines are at an angle of -10° or more and 10° or less. Therefore, it includes the case where the angle is between -5° and 5°. "Perpendicular" means that two straight lines are arranged at an angle of 80° or more and 100° or less. Therefore, it also includes cases where the angle is between 85° and 95°.

[0033] In the embodiment, the conductive film may be made of, for example, aluminum, titanium, chromium, or cobalt. Nickel, Copper, Yttrium, Zirconium, Molybdenum, Ruthenium, Silver, Tanta A conductive film containing titanium or tungsten may be used as a single layer or a stacked layer. Examples of conductive films having transparency include an In-Zn-W oxide film, an In-Sn oxide film, Oxide films such as In-Zn oxide film, indium oxide film, zinc oxide film and tin oxide film Furthermore, the oxide film described above can be easily formed even if trace amounts of Al, Ga, Sb, F, etc. are added. Also, a thin metal film that transmits light (preferably, 5 nm to 30 nm) For example, a 5 nm thick Ag film, Mg film, or Ag-Mg alloy film can be used. A gold film may be used. Alternatively, a film that efficiently reflects visible light may be, for example, a lithium , containing aluminum, titanium, magnesium, lanthanum, silver, silicon or nickel A membrane may be used.

[0034] The insulating film may be made of, for example, aluminum oxide, magnesium oxide, silicon oxide, Silicon oxynitride, silicon nitride oxide, silicon nitride, gallium oxide, germanium oxide , yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide Alternatively, an insulating film containing tantalum oxide may be used as a single layer or a multilayer. Resin films such as imide resin, acrylic resin, epoxy resin, and silicone resin may also be used. do not have.

[0035] <About the capacitor element> A capacitor according to one embodiment of the present invention will be described below with reference to FIG.

[0036] 1A, 1B, and 1C show examples of cross-sectional views of a capacitor element.

[0037] The capacitor shown in FIG. 1A includes a conductive film 104 over a substrate 100 and an insulating film over the conductive film 104. 112, a conductive film 116 overlapping the conductive film 104 via the insulating film 112, and The insulating film 118 has a thick region and a thin region, and the insulating film 118 is conductive through the thin region. The conductive film 114 overlaps the insulating film 112 and the conductive film 116. The insulating film 118 is electrically connected to the conductive film 104 through the opening in the insulating film 118 .

[0038] The capacitor element shown in FIG. 1B is made up of a conductive film 104 on a substrate 100 and a thick region on the conductive film 104. The insulating film 112 has a thin region and a thin region, and the conductive film 10 is formed through the thin region of the insulating film 112. 4, an insulating film 118 on the conductive film 116, and a conductive film 116 The conductive film 114 overlaps the insulating film 112 and the conductive film 116. The insulating film 118 is electrically connected to the conductive film 104 through the opening in the insulating film 118 .

[0039] The capacitor element shown in FIG. 1C includes a conductive film 104 on a substrate 100 and a thick region on the conductive film 104. The insulating film 112 has a thin region and a thin region, and the conductive film 10 is formed through the thin region of the insulating film 112. a conductive film 116 overlapping the insulating film 14 and having thick and thin regions on the conductive film 116; 18 and a conductive film 114 overlapping the conductive film 116 via a thin region of the insulating film 118. The conductive film 114 is exposed to the insulating film 112 through the openings in the insulating film 118. 104 and electrically connected to each other.

[0040] For example, a transistor or a capacitor can be manufactured using various substrates. The type of substrate is not limited to a specific one. An example of the substrate is a semiconductor substrate (e.g., For example, single crystal substrate or silicon substrate), SOI substrate, glass substrate, quartz substrate, plastic Metal substrate, stainless steel substrate, substrate with stainless steel foil , tungsten substrate, substrate with tungsten foil, flexible substrate, bonded foil Examples of substrates include glass substrates, glass films, and paper containing fibrous materials. barium borosilicate glass, aluminoborosilicate glass, or soda lime glass. Examples of flexible substrates include polyethylene terephthalate (PET), Representative examples include polyethylene naphthalate (PEN) and polyethersulfone (PES). Plastic or flexible synthetic resin such as acrylic. Examples of films include polypropylene, polyester, polyvinyl fluoride, or poly Examples of base films include polyester, polyamide, and poly Imide, inorganic vapor deposition film, or paper. In particular, semiconductor substrates or SOI substrates By manufacturing transistors using a substrate, etc., characteristics, size, or shape can be It is possible to manufacture transistors with small size, high current capability, and low variation. When a circuit is constructed using such transistors, it is possible to reduce the power consumption of the circuit or This allows for a high degree of integration of circuits.

[0041] Note that transistors and capacitors are fabricated using a substrate, and then the transistors and capacitors are fabricated on another substrate. The transistors and capacitors may be transposed and placed on a different substrate. An example of a substrate onto which the transistors and capacitors are transferred is In addition to the substrates that can be made, paper substrates, cellophane substrates, stone substrates, wood substrates, cloth substrates, etc. Substrates (natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester) or recycled fibers (including acetate, cupra, rayon, recycled polyester, etc.), Leather substrates or rubber substrates are available. By using these substrates, Fabrication of transistors, fabrication of low-power transistors, fabrication of durable devices, heat resistance It is possible to provide the device with increased durability, lighter weight, or thinner thickness.

[0042] It is possible to fabricate all of the circuits required to realize a given function on the same substrate. This allows for cost reduction by reducing the number of components, or reducing the number of connection points with circuit components. The reduction in number of components can improve reliability.

[0043] It is not necessary to fabricate all of the circuits required to realize a given function on the same substrate. In other words, part of the circuitry required to achieve a given function is fabricated on a certain substrate, and Other parts of the circuitry required to achieve a specific function may be fabricated on other substrates. For example, part of the circuitry required to realize a given function is fabricated on a glass substrate, and Another part of the circuitry required to realize the function is fabricated on the semiconductor substrate (or SOI substrate). Then, another part of the circuit necessary to realize a predetermined function can be created. The semiconductor substrate (also called IC chip) is then processed using COG (Chip On Glass) technology. ) to connect to the glass substrate and place the IC chip on the glass substrate. Alternatively, the IC chip can be attached using a TAB (Tape Automated Bonding) g), COF (Chip On Film), SMT (Surface Mount T It is possible to connect to the glass substrate using a printed circuit board or other similar technology. In this way, part of the circuit is fabricated on the same substrate as the pixel section, Cost reduction by reducing the number of parts, or reliability improvement by reducing the number of connections to circuit components In particular, circuits with high drive voltages or circuits with high drive frequencies In many cases, power consumption is high in circuits such as The pixel part is fabricated on a separate substrate to form an IC chip. This can prevent an increase in power consumption.

[0044] The capacitor element shown in FIGS. 1A, 1B, and 1C includes a conductive film 104, an insulating film 11, and a 2 and a conductive film 116, and a capacitance element C1 having the conductive film 116, an insulating film 118 and a conductive and a capacitance element C2 having a film 114. Therefore, as shown in FIGS. The capacitance element shown in FIG. 1(C) is a circuit in which a capacitance element C1 and a capacitance element C2 are connected in parallel. This can be shown in the figure (see Figure 1(D)). That is, Figure 1(A), Figure 1(B) and Figure 1 The capacitance of the capacitive element shown in (C) is the sum of the capacitance of the capacitive element C1 and the capacitance of the capacitive element C2.

[0045] In the capacitor element shown in FIG. 1A, the capacitor element C2 uses a thin region of the insulating film 118. Therefore, the capacitance per occupied area can be increased. In the device, the capacitance element C1 utilizes a thin region of the insulating film 112, so In the capacitor shown in FIG. 1C, the capacitor C1 is an insulating The capacitor element C1 utilizes a thin region of the insulating film 112, and the capacitor element C2 utilizes a thin region of the insulating film 118. , the capacity per occupied area can be increased.

[0046] In this way, the capacitance elements shown in FIGS. 1(A), 1(B) and 1(C) have a capacitance per occupied area of It is a capacitive element with a large capacitance.

[0047] By using the capacitor elements shown in FIGS. 1(A), 1(B), and 1(C) in a semiconductor device, This allows for a higher degree of integration of the semiconductor device. A semiconductor device having an element can be provided.

[0048] The capacitance elements shown in FIGS. 1A, 1B, and 1C are, for example, transistors. For example, the conductive film 104 can be formed in the same process. The conductive film can be used as a gate electrode of a transistor. The insulating film formed through the same process as the film 112 is used as the gate insulating film of the transistor. In addition, for example, a conductive film formed through the same process as the conductive film 116 can be It can be used as a source electrode or a drain electrode of a transistor. The insulating film formed through the same process as the insulating film 118 is used as a protective insulating film for the transistor. In addition, for example, a conductive film formed through the same process as the conductive film 114 can be The conductive film 114 can be used as a second gate electrode of the transistor. When the conductive film formed through the process is used as the second gate electrode of a transistor, The insulating film formed through the same process as the insulating film 118 is used as the second gate insulating film of the transistor. The thick and thin insulating film regions that form the capacitance element can be made to function. is a photolithography process using a multi-tone mask (also called a gray-tone mask). Therefore, it is possible to form the mask by using a multi-tone mask. This may enable the company to increase productivity.

[0049] In this way, by combining a transistor and a capacitor, any semiconductor device can be manufactured. Examples of the semiconductor device include a display device, a memory device, and a processor. The capacitance elements shown in FIGS. 1(A), 1(B) and 1(C) have a capacitance per occupied area of Since the capacitance of the capacitor is large, it is suitable for use in display devices with high display quality and memory devices with excellent retention characteristics. It is possible to realize devices, processors with low power consumption, etc. This makes it possible to realize a highly integrated memory device and processor.

[0050] At least the conductive film constituting the capacitance element shown in FIGS. 1(A), 1(B) and 1(C) In that case, for example, a light-transmitting conductive film may be used for the capacitor element. In some cases, the aperture ratio of the display device can be increased. It may be possible to reduce the power consumption of the device.

[0051] However, one aspect of the embodiment of the present invention is not limited to this. Depending on the situation, the insulating film of the capacitive element does not need to be thin.

[0052] <About the display device> A display device according to one embodiment of the present invention will be described below with reference to FIGS.

[0053] Display elements used in display devices include liquid crystal elements (also called liquid crystal display elements), light-emitting elements, and the like. The light-emitting element can be a light-emitting display element. Therefore, the category includes elements whose brightness can be controlled, specifically inorganic EL, organic EL, etc. Also, electronic ink, electrophoretic elements, etc., which change contrast due to electrical effects, Display media, grating light valves (GLVs), plasma display panels (PDP), MEMS (Micro-Electro-Mechanical Systems), Digital Micro Chromatic mirror device (DMD), DMS (digital micro shutter), IMOD (Interference modulation) element, electrowetting element, pressure Electroceramic displays, carbon nanotubes, etc. can also be used as display elements. In the following, a display device using an EL element (EL display device) will be described as an example of the display device. ) and a display device using a liquid crystal element (liquid crystal display device) will be described.

[0054] The display device described below is a panel in which a display element is sealed, and a connector for the panel. This includes modules in which ICs including controllers are mounted.

[0055] The display device shown below refers to an image display device or a light source (including a lighting device). Also, connectors, such as FPC, modules with TCP attached, and printers at the end of TCP The IC (integrated circuit) is mounted directly on the module or display element with a printed wiring board using the COG method. All modules mounted on the display device are also included in the display device.

[0056] 2A and 2B are diagrams illustrating an example of an EL display device according to one embodiment of the present invention. FIG. 2(B) is a top view showing the entire EL display device. 2(C) is a cross section of MN corresponding to a part of the dashed line MN in FIG. 2(B).

[0057] FIG. 2A is an example of a circuit diagram of a pixel used in an EL display device.

[0058] In this specification, the terms "active elements" and "passive elements" are used interchangeably. For all terminals of elements such as capacitors and resistors, the connection destination must be specified. However, a person skilled in the art may be able to compose an aspect of the invention. Even if the destination is not specified, one aspect of the invention can be said to be clear. When the content is described in this specification, etc., one aspect of the invention that does not specify the connection destination is In particular, if the terminal is connected to multiple When multiple locations are expected, there is no need to limit the connection destination of the terminal to a specific location. Therefore, active elements (transistors, diodes, etc.) and passive elements (capacitance elements, resistance elements) By specifying the connection destinations of only some of the terminals possessed by devices such as It may be possible to configure a different embodiment.

[0059] 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. It may be possible for a person skilled in the art to identify an invention. A person skilled in the art may be able to identify an invention by at least specifying the function. In other words, if the function is specified, it can be said that one aspect of the invention is clear. It may be possible to determine that one aspect of the invention is described in the present specification. Therefore, even if the function of a circuit is not specified, specifying the connection destination can be considered an aspect of an invention. and can constitute one aspect of the invention. Even if the connection destination of a certain circuit is not specified, if the function is specified, it can be considered as one aspect of the invention. What is disclosed can constitute an aspect of the invention.

[0060] The EL display device shown in FIG. 2A includes a switching element 743, a transistor 741, a capacitor It has an element 742 and a light-emitting element 719.

[0061] Note that FIG. 2A and the like are examples of circuit configurations, and therefore, if a transistor is further added, Conversely, at each node in Figure 2(A), transistors, switches, and receivers can be used. It is also possible to avoid adding any moving elements.

[0062] The gate of the transistor 741 is connected to one end of the switch element 743 and one end of the capacitor element 742. The source of the transistor 741 is electrically connected to the other electrode of the capacitor 742. and electrically connected to one electrode of the light-emitting element 719. The drain of the switch element 741 is supplied with a power supply potential VDD. The other end of the switch element 743 is connected to the signal line 7 The other electrode of the light-emitting element 719 is electrically connected to the light-emitting element 44. A constant potential is applied to the other electrode of the light-emitting element 719. The constant potential is the ground potential GND or a potential lower than that.

[0063] It is preferable to use a transistor as the switch element 743. This allows the pixel area to be reduced, resulting in an EL display device with high resolution. The switching element 743 is a transistor manufactured through the same process as the transistor 741. The use of a photoresist can increase the productivity of EL displays.

[0064] 2B is a top view of the EL display device. The EL display device is made up of a substrate 700 and a substrate 75. 0, a sealant 734, a driving circuit 735, a driving circuit 736, a pixel 737, and an FPC The sealing material 734 covers the pixel 737, the driver circuit 735, and the driver circuit 736. 36 is disposed between the substrate 700 and the substrate 750. Alternatively, the driving circuit 736 may be disposed outside the sealing material 734 .

[0065] FIG. 2C is a cross-sectional view of the EL display device corresponding to a part of the dashed line MN in FIG. 2B. do.

[0066] In FIG. 2C, a transistor 741 is illustrated, which includes a conductive film 704a and a conductive film An insulating film 712a on 704a, an insulating film 712b on the insulating film 712a, and an insulating film 712b The semiconductor film 706 overlapping the conductive film 704a and the conductive film 71 in contact with the semiconductor film 706 are 6a and the conductive film 716b, and the semiconductor film 706, the conductive film 716a, and the conductive film 716 b, an insulating film 718a on the insulating film 718a, and an insulating film 718b on the insulating film 718b. an insulating film 718c, and a conductive film 714a that is on the insulating film 718c and overlaps with the semiconductor film 706; Note that the structure of the transistor 741 is just an example, and the structure shown in FIG. It may have a different structure from the original.

[0067] Therefore, in the transistor 741 shown in FIG. 2C, the conductive film 704a The insulating film 712a and the insulating film 712b function as gate insulating films, and the conductive film 712b functions as a conductive electrode. The conductive film 716a functions as a source electrode, and the conductive film 716b functions as a drain electrode. The insulating films 718a, 718b, and 718c function as gate insulating films. The conductive film 714a functions as a gate electrode. Therefore, the electrical characteristics of the conductive film 704a, the conductive film 716a, and the conductive film It is preferable that at least one of the conductive film 716b and the conductive film 714a has a light-blocking property.

[0068] The interface between the insulating film 718a and the insulating film 718b is shown by a broken line. For example, when the insulating film 718a and the insulating film 718b are Therefore, when the same type of insulating film is used, it may be difficult to distinguish between the two depending on the observation method.

[0069] In FIG. 2C, a conductive film 704b over a substrate and a conductive film 704b an insulating film 712a, an insulating film 712b on the insulating film 712a, and a conductive film 712b on the insulating film 712b. a conductive film 716a overlapping the conductive film 704b; an insulating film 718a on the conductive film 716a; An insulating film 718b on the insulating film 718a, an insulating film 718c on the insulating film 718b, and an insulating film 718c and a conductive film 714b that is located above and overlaps the conductive film 716a. In the region where the insulating film 714b overlaps, the insulating film 718a and the insulating film 718b are partially removed. The structure is shown below.

[0070] In the capacitor 742, the conductive film 704b and the conductive film 714b function as one electrode. The conductive film 716a functions as the other electrode.

[0071] Therefore, the capacitor 742 can be formed using the same film as that of the transistor 741. In addition, it is preferable that the conductive films 704a and 704b be made of the same type of conductive film. In that case, the conductive film 704a and the conductive film 704b can be formed through the same process. In addition, the conductive films 714a and 714b are preferably made of the same type of conductive film. In this case, the conductive films 714a and 714b can be formed in the same process. .

[0072] The capacitor 742 shown in FIG. 2C has a structure similar to that of the capacitor shown in FIG. Similar to the capacitor shown in FIG. 1(A), this capacitor has a large capacitance per occupied area. Therefore, the EL display device shown in FIG. 2(C) has high display quality. The capacitor 742 is formed by thinning the overlapping region of the conductive film 716a and the conductive film 714b. 7, the insulating film 718a and the insulating film 718b have been partially removed. The capacitor element according to the embodiment is not limited to this. In order to thin the overlapping region of the insulating film 714b, a part of the insulating film 718c is removed. It's okay to do so.

[0073] Note that the structure of the capacitor 742 is an example and may be different from the structure shown in FIG. For example, in FIG. 3A, the capacitor 742 may be the same as the capacitor shown in FIG. Specifically, the EL display device has a structure similar to that of the capacitance element shown in FIG. The electrode 742 is formed by insulating film 712b in a region where the conductive film 704b and the conductive film 716a overlap. The capacitor 742 shown in FIG. 3A has a structure in which the conductive film 704 In order to thin the region where the insulating film 712b and the conductive film 716a overlap, a part of the insulating film 712b is removed. However, the capacitor according to one embodiment of the present invention is not limited to this structure. For example, in order to thin the region where the conductive film 704b and the conductive film 716a overlap, the insulating film 712 It may have a structure in which a is partially removed.

[0074] The structure of the capacitor 742 is an example, and the structures shown in FIGS. 2C and 3A may be different. For example, in FIG. 3B, the capacitor 742 is This is an EL display device having a structure similar to that of the capacitance element shown in FIG. The capacitor 742 shown in FIG. 7B is an insulating film in a region where the conductive film 704b and the conductive film 716a overlap each other. A portion of the conductive film 712b is removed, and in the area where the conductive film 716a and the conductive film 714b overlap, The insulating film 718a and the insulating film 718b have a structure in which a part of the insulating film 718a and the insulating film 718b are removed. ) is formed by thinning the overlapping region of the conductive film 716a and the conductive film 714b. Therefore, the insulating film 718a and the insulating film 718b are partially removed. The capacitor according to one embodiment is not limited to this. In order to thin the overlapping region of the conductive film 714b, a part of the insulating film 718c is removed. The capacitor 742 shown in FIG. A structure in which a part of the insulating film 712b is removed to thin the area where the insulating film 712b overlaps the conductive film 716a. However, the capacitor according to one embodiment of the present invention is not limited thereto. For example, In order to thin the overlapping region of the conductive film 704b and the conductive film 716a, It may have a structure in which a portion is removed.

[0075] In FIGS. 2C, 3A, and 3B, the transistor 742 is connected to a part of the capacitor element 742. 4 shows a structure in which a conductive film 716a functions as a source electrode of the capacitor 41. A structure in which a semiconductor film 707 is included in a part of the element 742 is shown.

[0076] In FIG. 4A, a conductive film 704b over a substrate and a conductive film 704b an insulating film 712a, an insulating film 712b on the insulating film 712a, and a conductive film 712b on the insulating film 712b. a semiconductor film 707 overlapping the conductive film 704b, an insulating film 718a on the semiconductor film 707, and an insulating film An insulating film 718b on the insulating film 718a, an insulating film 718c on the insulating film 718b, and an insulating film 718c and a conductive film 714b that is located above and overlaps the semiconductor film 707. In the region where the insulating film 714b overlaps, the insulating film 718a and the insulating film 718b are partially removed. The structure is shown below.

[0077] The semiconductor film 707 is preferably a semiconductor film that functions as an electrode of the capacitor 742. Therefore, it is preferable that the semiconductor film 707 is a degenerate semiconductor. Even if the carrier density of the conductive film 704b is low, the conductive film 704b and / or the conductive film 714b Carriers can be induced in the semiconductor film 707 by the electric field.

[0078] It is preferable that the semiconductor film 706 and the semiconductor film 707 are made of the same kind of semiconductor film. In this case, the semiconductor film 706 and the semiconductor film 707 can be formed through the same process.

[0079] By the way, the semiconductor film 706 functions as a semiconductor film of the transistor 741. It is preferable to use a semiconductor film with low rear density. It is preferable to use a semiconductor film with a high carrier density because it functions as an electrode. In the case where the semiconductor film 706 and the semiconductor film 707 are formed through the same process, Therefore, it is preferable to separately manufacture the layers so that the carrier density of each layer is appropriate.

[0080] For example, the semiconductor film 706 and the semiconductor film 707 are formed of semiconductor films with high carrier density. The carrier density of the semiconductor film 706 may be reduced in a later step. As a method for reducing the carrier density, for example, when the semiconductor film 706 is an n-type semiconductor, If the semiconductor film 706 is a p-type semiconductor, an acceptor may be implanted. Alternatively, a carrier generation source in the semiconductor film 706 may be reduced. When the semiconductor film 706 is an oxide semiconductor film, oxygen vacancies in the oxide semiconductor film capture hydrogen. Therefore, in the case of an oxide semiconductor film, electrons can be generated by capturing oxygen. The oxygen deficiency can be reduced by supplying oxygen or the hydrogen can be reduced by applying heat. The carrier density of the semiconductor film 706 can be reduced.

[0081] Alternatively, for example, the semiconductor film 706 and the semiconductor film 707 may be made of a semiconductor having a low carrier density. Alternatively, a semiconductor film may be formed on the semiconductor film 707, and the carrier density of the semiconductor film 707 may be increased in a later process. As a method for increasing the carrier density of the semiconductor film 707, for example, a dopant is added to the semiconductor film 707. Alternatively, a carrier generation source for the semiconductor film 707 may be formed. When the semiconductor film 707 is an oxide semiconductor film, hydrogen is captured in oxygen vacancies in the oxide semiconductor film. Therefore, in the case of an oxide semiconductor film, the reduction The carriers of the semiconductor film 707 can be obtained by desorbing oxygen in a neutral environment or by supplying hydrogen. The density can be increased.

[0082] In the capacitor 742 illustrated in FIG. 4A, for example, the insulating film 718c is a semiconductor film By using an insulating film containing impurities that become a carrier generation source in the semiconductor film 707, The carrier density may be increased. Specifically, the semiconductor film 707 is an oxide semiconductor film. In this case, by using an insulating film containing hydrogen as the insulating film 718c, the carrier The hydrogen-containing insulating film can increase the hydrogen density. Therefore, the insulating film 718c and the semiconductor film 707 are preferably used. By adopting the structure in contact with the semiconductor film 7, the capacitance of the capacitor 742 can be increased and at the same time, Therefore, the carrier density of the SiO2 layer can be increased. The number of steps is reduced, and the productivity of the display device can be improved.

[0083] Note that the capacitor 742 shown in FIG. 4A is formed by overlapping the semiconductor film 707 and the conductive film 714b. In order to thin the region where the insulating film 718a and the insulating film 718b are to be formed, a structure in which a part of the insulating film 718a and the insulating film 718b are removed is used. However, the capacitor according to one embodiment of the present invention is not limited to this. In order to thin the overlapping region of the conductive film 707 and the conductive film 714b, a part of the insulating film 718c It may have a structure in which is removed.

[0084] As the capacitor 742 using the semiconductor film 707, the capacitor 74 shown in FIG. 4B shows an example different from that of the capacitor 742 shown in FIG. In the region where the insulating film 707 overlaps, a part of the insulating film 712b is removed. The capacitor 742 shown in FIG. 7B has a thin film formed by thinning the area where the conductive film 704b and the semiconductor film 707 overlap. In order to reduce the thickness, the insulating film 712b is partly removed. The capacitor element is not limited to this. For example, the conductive film 704b and the semiconductor film 70 In order to thin the overlapping region of the insulating film 712a, a part of the insulating film 712a may be removed. do not have.

[0085] In Figure 2(C), Figure 3(A), Figure 3(B), Figure 4(A) and Figure 4(B), FPC7 32 is connected to a wiring 733a via a terminal 731. A conductive film or a semiconductor film of the same kind as one of the conductive films or semiconductor films constituting the resistor 741 It is also acceptable to use

[0086] An insulating film 720 is provided over the transistor 741 and the capacitor 742. The insulating film 720 reaches the conductive film 716a which functions as a source electrode of the transistor 741. A conductive film 781 is disposed over the insulating film 720. 1 may be electrically connected to the transistor 741 through an opening in the insulating film 720.

[0087] A partition 784 having an opening reaching the conductive film 781 is provided over the conductive film 781. A light-emitting layer 782 is disposed on the wall 784 so as to be in contact with the conductive film 781 at the opening of the partition wall 784. A conductive film 783 is disposed over the light-emitting layer 782. The overlapping region of the conductive film 783 becomes the light-emitting element 719 .

[0088] So far, an example of an EL display device has been described. Next, an example of a liquid crystal display device will be described. do.

[0089] FIG. 5(A) is a circuit diagram showing an example of the configuration of a pixel of a liquid crystal display device. A transistor 751, a capacitor element 752, and an element in which liquid crystal is filled between a pair of electrodes (liquid crystal element) Child) 753.

[0090] In the transistor 751, one of the source and the drain is electrically connected to a signal line 755. The gate is electrically connected to a scan line 754 .

[0091] In the capacitor 752, one electrode is electrically connected to the other of the source and drain of the transistor 751. The other electrode is electrically connected to a wiring that supplies a common potential.

[0092] In the liquid crystal element 753, one electrode is electrically connected to the other of the source and drain of the transistor 751. The other electrode is electrically connected to a wiring that supplies a common potential. a common potential applied to a wiring to which the other electrode of the capacitor 752 is electrically connected; The common potential applied to the other electrode of the liquid crystal element 753 may be different from the common potential applied to the other electrode of the liquid crystal element 753 .

[0093] The liquid crystal display device will be described with the same top view as the EL display device. A cross-sectional view of the liquid crystal display device corresponding to the chain line MN is shown in FIG. The FPC 732 is connected to the wiring 733a via the terminal 731. The wiring 733a is , a conductive film or a semiconductor film of the same kind as the conductive film or the semiconductor film constituting the transistor 751 A semiconductor film may also be used.

[0094] For the transistor 751, refer to the description of the transistor 741. 752, refer to the description of the capacitor 742. Note that in FIG. 7B, the structure of the capacitor 752 corresponding to the capacitor 742 of FIG. For example, the capacitor 752 shown in FIG. A structure corresponding to the capacitor element 742 described above may also be used.

[0095] Note that when an oxide semiconductor film is used as the semiconductor film of the transistor 751, the off-state current is extremely low. Therefore, the charge held in the capacitor 752 Therefore, the voltage applied to the liquid crystal element 753 can be maintained for a long period of time. Therefore, when displaying a moving image or a still image with little movement, the transistor 751 is turned off. By setting the transistor 751 in this state, power for operating the transistor 751 is not required, and power consumption is low. In addition, the area occupied by the capacitor 752 can be reduced. Therefore, it is possible to provide a liquid crystal display device with a high aperture ratio or a high-definition liquid crystal display device. do.

[0096] An insulating film 721 is provided over the transistor 751 and the capacitor 752. The insulating film 721 has an opening that reaches the transistor 751. The conductive film 791 is connected to the transistor through the opening of the insulating film 721. 751 and electrically connected.

[0097] An insulating film 792 functioning as an alignment film is provided over the conductive film 791. A liquid crystal layer 793 is disposed on the liquid crystal layer 793. An insulating film 794 which functions as an alignment film is disposed on the liquid crystal layer 793. 94 is disposed on the insulating film 794. A spacer 795 is disposed on the insulating film 794. A conductive film 796 is disposed on the insulating film 794. 7 is placed.

[0098] By having the above-described structure, it is possible to provide a display device having a capacitor element with a small occupation area. Alternatively, a display device with high display quality can be provided. It is possible to provide a display device.

[0099] <About high-definition display devices> An example of a pixel that constitutes a high-definition EL display device will be shown below.

[0100] 6 shows a pixel of an EL display device. The EL display device shown in FIG. 6 includes a transistor 971 and , transistor 972, transistor 973, transistor 974, and transistor 975, a capacitance element 976, a light emitting element 919, a signal line SL, a power line PL1, and a power supply The scanning line PL2, the scanning line GL1, the scanning line GL2, and the scanning line GL3.

[0101] The potential of the pixel electrode of the light emitting element 919 is controlled in accordance with an image signal input to the pixel. Alternatively, the luminance of the light emitting element 919 is determined by the potential difference between the pixel electrode and the common electrode. Here, the anode of the light emitting element 919 functions as a pixel electrode, and the cathode functions as a common electrode. It works.

[0102] FIG. 6A shows a circuit diagram of a pixel, and the connection relationship between each element and wiring will be described below.

[0103] The transistor 971 controls the conduction state between the signal line SL and one electrode of the capacitor 976. The other electrode of the capacitor 976 is connected to the source of the transistor 972, The transistor 973 is electrically connected to one of the power supply lines PL2 and the drain of the transistor 974. The transistor 974 has a function of controlling the conduction state between the gate of the transistor 974 and the gate of the transistor 972. A gate electrode of the capacitor 976 is connected to the gate of the transistor 972. The transistor 975 has a function of connecting one of the source and drain of the transistor 972. and the anode of the light-emitting element 919. 2 has a function of controlling the conduction state between the power supply line PL1 and the other electrode of the capacitor element 976. do.

[0104] The conduction state of the transistor 971 is determined by electrically connecting the gate of the transistor 971 to the The conduction state of the transistor 973 is controlled by the potential of the scanning line GL1. The gate of the transistor 973 is controlled by the potential of the scanning line GL1 electrically connected to the gate of the transistor 973. The conduction state of the transistor 974 is determined by the scan line GL The conduction state of the transistor 975 is controlled by the potential of the transistor 975. It is controlled by the potential of the scanning line GL3 electrically connected to the gate.

[0105] Transistor 971, transistor 972, transistor 973, transistor 974, and The transistor 975 is preferably formed using an oxide semiconductor or silicon. When an oxide semiconductor is used for the transistor 971, the transistor 973, and the transistor 974, , the off-state current of the transistor 971, the transistor 973, and the transistor 974 is This is particularly preferable because the size can be reduced by the above-described method. By using the transistors 971, 973, and 974 in the pixel, Compared to using transistors made of semiconductors such as silicon and germanium, This can prevent leakage of charges accumulated in the gate of the transistor 972.

[0106] Therefore, like a still image, the same image information is displayed on the pixel portion over several consecutive frame periods. In cases where an image signal having information is written, the driving frequency can be lowered. In other words, even if the number of times that image signals are written to the pixel section within a certain period is reduced, the image For example, a highly purified oxide semiconductor can be used in the transistor 9 71, the transistor 973, and the transistor 974, The interval can be set to 10 seconds or more, 30 seconds or more, or 1 minute or more. The longer the interval between writes, the more power consumption can be reduced.

[0107] Furthermore, the potential of the image signal can be maintained for a longer period of time. Even if the capacitance of the capacitor 976 for holding the potential of the gate of the transistor 972 is reduced, That is, the area occupied by the capacitor element 976 can be reduced. Therefore, the aperture ratio of the pixel can be increased. This will extend the life of 919 and improve the reliability of EL display devices.

[0108] In FIG. 6A, the pixel may include a transistor, a diode, a resistor, etc., as needed. The semiconductor device may further include other elements such as resistors, capacitors, and inductors.

[0109] In addition, in FIG. 6A, the transistor 971, the transistor 972, and the transistor 9 The transistor 73 and the transistor 975 have a second gate (also referred to as a back gate). Transistor 971, transistor 972, transistor 973 and transistor 97 In 5, the second gate is electrically connected to the gate. The drain current can be increased by the amount of the electric field applied from the second By having a gate, the drain voltage to saturate the drain current of the transistor is That is, since it is easy to make the drain current constant, the light emitting element 919 Therefore, it is possible to easily control the gradation of the light emitting element 919. This makes it easier to realize a display device with high display quality.

[0110] In addition, in FIG. 6A, the transistor 974 does not have a second gate. By reducing the parasitic capacitance associated with the gate of the transistor 974, This is because the ability to correct the threshold voltage can be improved.

[0111] In FIG. 6A, a transistor 971, a transistor 972, a transistor 973, and Transistor 975 has a second gate and transistor 974 does not have a second gate. The case where the second gate is not provided is shown as an example, but the present invention is not limited to this. The value can be changed as appropriate depending on the structure of the transistor.

[0112] Note that FIG. 6A illustrates a case where all the transistors are n-channel transistors. If all the transistors in a pixel are of the same channel type, The manufacturing process of the transistor can be simplified compared to when a transistor is provided. In the EL display device according to one embodiment of the present invention, all the transistors in a pixel are n-channel transistors. This is not limited to the case where:

[0113] Next, the operation of the pixel shown in FIG. 6(A) will be described with reference to FIGS.

[0114] FIG. 7A shows timing charts showing the potentials of the scanning lines GL1 to GL3 and the potential of the signal line SL. FIG. 7B is a timing chart showing the period T1 during which the initialization operation is performed in FIG. 7A. In response to the voltages of the scanning lines GL1 to GL3 and the transistors 971 to 974, The potentials of the scanning lines GL1 to GL3 are at a low level. If it is low, it is represented as L, and if it is high level, it is represented as H.

[0115] In the period T1, a low level potential is applied to the scanning line GL1, and a low level potential is applied to the scanning line GL2. A high level potential is applied to the scanning line GL3. Transistor 975 is turned on, and transistors 971, 973 and 974 are turned on. During the period T1, the resistor 974 is in a non-conductive state due to the influence of the previous light emitting operation. Transistor 972 begins in a conducting state.

[0116] Further, a potential Vano is applied to the power supply line PL1, and a potential Vc is applied to the cathode of the light emitting element 919. The power supply line PL2 is supplied with a potential V0, and the signal line SL is supplied with an image The potential V0 is the threshold voltage of the transistor 972. The voltage Vth is a potential obtained by adding the threshold voltage Vthe of the light emitting element 919 to the potential Vcat. is higher than the sum of the threshold voltage Vth of the transistor 972 and the potential Vano. Preferably it is low.

[0117] During the period T1, the transistor 972, the transistor 975, and the capacitance element 976 The potential in node A is initialized to a potential close to the threshold voltage Vthe of the light emitting element 919. It is possible.

[0118] 8A shows the potential Vdata of the signal line SL and the transistor 97 in FIG. The scanning lines GL1 to GL3 correspond to the period T2 for acquiring the threshold voltage Vth of the scanning line GL2. , and the conduction states of the transistors 971 to 975.

[0119] In the period T2, a high level potential is applied to the scanning line GL1, and a low level potential is applied to the scanning line GL2. In the period T2, a high-level potential is applied to the scanning line GL1, and a low-level potential is applied to the scanning line GL2. A potential V0 is applied to the gate of the transistor 972. The charge in the capacitance element 976 is released, and the potential of the node A, which was at the potential Vcat, begins to rise. Finally, when the potential of node A reaches V0-Vth, the gate of transistor 972 The voltage drops to the threshold voltage Vth, and transistor 972 becomes non-conductive. In addition, one electrode of the capacitor 976 (referred to as a node B) is supplied with a potential Vdata. Given.

[0120] FIG. 8B shows the scanning lines GL1 to GL2 corresponding to the period T3 showing light emission in FIG. 7A. The potential of the scan line GL3 and the conduction states of the transistors 971 to 975 are shown. .

[0121] During the period T3, a low level potential is applied to the scanning line GL1, and a high level potential is applied to the scanning line GL2. A high-level potential is applied to the scanning line GL1, and a high-level potential is applied to the scanning line GL2. The transistor 974 and the transistor 975 are turned on. The transistor 973 is turned off. At this time, the potential applied to the scanning line GL1 is switched from high level to low level, and then the potential applied to the scanning line G It is preferable to switch the potential applied to the scanning line GL2 and the scanning line GL3 from low level to high level. By doing so, the potential at the node A caused by the switching of the potential applied to the scanning line GL1 is This can suppress fluctuations in the potential.

[0122] During the period T3, the potential Vdata is applied to the gate of the transistor 972 by the above operation. Therefore, the gate voltage Vgs of the transistor 972 becomes Vdata-V0+Vth. Therefore, the gate voltage Vgs of the transistor 972 is multiplied by the threshold voltage Vth. The value can be set as follows.

[0123] Specifically, the current value supplied to the light emitting element 919 is I OLED Then, I OLED =0 .5β(Vgs-Vth) 2 where β is a parameter specific to the transistor. Specifically, β = (W / L) μ FE Cox. W is the transition denotes the channel width of the transistor, L denotes the channel length of the transistor, and μ FE is a transistor where Cox is the gate capacitance of the transistor. Substituting the voltage Vgs=Vdata-V0+Vth, I OLED =0.5β(Vdata -V0) 2 It is expressed as:

[0124] That is, in the pixel of the EL display device shown in FIG. 6A, the threshold voltage Vt The variation in h affects the current I supplied to the light emitting element 919. OLED Reduce the impact on It can be seen that the circuit configuration can be realized. Even if the threshold voltage Vth fluctuates, the current value I OLE D Therefore, it is possible to provide a display device with less display unevenness. It is possible.

[0125] Next, an example of the structure of an EL display device having a threshold voltage correction function shown in FIG. 6(A) will be described. This will be explained using Fig. 6(B) and Fig. 6(C). In C), for ease of understanding, some components such as the light-emitting element 919 are omitted.

[0126] FIG. 6(B) is a top view corresponding to the pixel of the EL display device shown in FIG. 6(A). The size of one pixel of a display device is expressed as x μm x y μm. For example, the size of one pixel of an EL display device is 38.25 μm × 12.75 μm (664 ppi equivalent).

[0127] In this way, in the pixel of a high-definition EL display device, the area occupied by the capacitor element 976 is sufficiently secured. In the circuit configuration shown in FIG. 6 is preferably twice the parasitic capacitance associated with the gate of transistor 972, more preferably The capacity may be 5 times, more preferably 10 times.

[0128] FIG. 6(C) is a cross-sectional view corresponding to the dashed dotted line F1-F2 and the dashed dotted line F3-F4 in FIG. 6(B). is.

[0129] The pixel shown in FIG. 6C includes a conductive film 904a and a conductive film 904b on a substrate 900, and a conductive film The insulating film 912a on the conductive film 904a and the conductive film 904b, and the insulating film 912a on the insulating film 91 2b, a semiconductor film 906 that is on the insulating film 912b and overlaps with the conductive film 904a, and a semiconductor film 9 The conductive film 916a and the conductive film 916b are in contact with the semiconductor film 906. an insulating film 918a on the conductive film 916a and on the conductive film 916b; and an insulating film 918b on the insulating film 918a. an insulating film 918c on the insulating film 918b; a conductive film 914a that is located on the insulating film 918c and overlaps with the conductive film 916b; , the insulating film 908 on the insulating film 918c, the conductive film 914a, and the conductive film 914b, and the insulating film 908 on the insulating film 918c, the conductive film 914a, and the conductive film 914b. The conductive film 926 includes a conductive film 926a, a conductive film 926b, and a conductive film 926c over the film 908.

[0130] The conductive film 926b is formed by insulating films 918a, 918b, and 918c. The conductive film 914a is electrically connected to the conductive film 916b through the opening in the conductive film 908. The insulating film 912a, the insulating film 912b, the insulating film 918a, the insulating film 918b, and the insulating film 9 The insulating film 918a and the conductive film 904a are electrically connected to each other through the openings in the insulating film 918c. The insulating film 918b has an opening in a part above the conductive film 916a, and the conductive film 916b is 916a and insulating film 918c are in contact with each other.

[0131] In the transistor 975, the conductive film 904a functions as a gate electrode, and the insulating film 912 The insulating film 912a and the insulating film 912b function as a gate insulating film, and the conductive film 916a functions as a source electrode. The conductive film 916b functions as a drain electrode, and the insulating film 918a and the insulating film 918b function as a drain electrode. b and the insulating film 918c function as a gate insulating film, and the conductive film 914a functions as a gate electrode. It works like this.

[0132] In addition, in the capacitor 976, the conductive film 904b and the conductive film 914b are used as one electrode. The conductive film 916a functions as the other electrode.

[0133] Note that the transistor 975 has a structure similar to that of the transistor 741. For the transistor 975, refer to the description of the transistor 741. , transistor 971, transistor 972, transistor 973 and transistor 9 The description of the transistor 741 can also be referred to for the capacitor 976. The capacitor 976 has a structure similar to that of the capacitor 742. Please refer to the description of the quantum element 742.

[0134] In the pixels shown in FIGS. 6B and 6C, the area occupied by the capacitor element 976 can be reduced. Therefore, this structure is suitable for high-definition EL display devices.

[0135] Next, a method for fabricating the layer structure of the pixel shown in FIG. 6(B) and FIG. 6(C) will be described with reference to FIGS. 16. The top views are shown in FIGS. 9(A), 10(A), 11(A), and 1 2(A), 13(A), 14(A), 15(A) and 16(A), The corresponding cross-sectional views are shown in Fig. 9(B), Fig. 10(B), Fig. 11(B), Fig. 12(B), Fig. 1 3(B), 14(B), 15(B) and 16(B).

[0136] First, a conductive film 904a, a conductive film 904b, a conductive film 904c, and a conductive film 904 d, a conductive film 904e and a conductive film 904f are formed (see FIGS. 9(A) and 9(B)). The conductive film 904a is connected to the scanning line GL3 and the gate electrode of the transistor 975. The conductive film 904b functions as one electrode of the capacitor 976. The conductive film 904c functions as a power supply line PL2. As the gate electrodes of the scan line GL1 and the transistors 971 and 973 The conductive film 904e is connected to the scanning line GL2 and the gate electrode of the transistor 974. The conductive film 904f functions as a gate electrode of the transistor 972.

[0137] Next, an insulating film 912a is formed. Next, an insulating film 912b is formed on the insulating film 912a. Note that the insulating films 912a and 912b are formed between the transistor 971 and the transistor 9 72, gate insulation of transistor 973, transistor 974 and transistor 975 It acts as a membrane.

[0138] Next, the semiconductor film 906, the semiconductor film 906a in the same layer as the semiconductor film 906, and the semiconductor film 906b, semiconductor film 906c, and semiconductor film 906d are formed (FIG. 10(A) and FIG. 10(B). Note that the semiconductor film 906 functions as a semiconductor film of the transistor 975. The semiconductor film 906a functions as a semiconductor film of the transistor 971. The semiconductor film 906b functions as a semiconductor film of the transistor 974. The film 906c functions as a semiconductor film of the transistor 973. functions as a semiconductor film of the transistor 972.

[0139] Next, an opening 928a reaching the conductive film 904b is formed in the insulating film 912a and the insulating film 912b. , an opening 928b reaching the conductive film 904c, and an opening 928 c is formed (see Figures 11(A) and 11(B)).

[0140] Next, the conductive film 916a, the conductive film 916b, the conductive film 916c, the conductive film 916d, and the conductive film The conductive film 916d is formed by the opening 916e, the conductive film 916f, and the conductive film 916g. The conductive film 916f is electrically connected to the conductive film 904b through the opening 928a. The conductive film 916g is electrically connected to the conductive film 904c through the opening 928b. 28c and electrically connected to the conductive film 904f (see FIGS. 11(A) and 11(B)). The conductive film 916a forms a source electrode of the transistor 972 and a drain electrode of the transistor 97 The conductive film 971 functions as a drain electrode of the capacitor 975 and the other electrode of the capacitor 976. The conductive film 916b functions as a source electrode of the transistor 975. The conductive film 91 functions as a source electrode or a drain electrode of the transistor 971. 6d is the source or drain electrode of the transistor 971 and the transistor 97 The conductive film 916e functions as a source electrode or a drain electrode of the transistor 4. The conductive film 916f functions as a drain electrode of the transistor 972. The conductive film 916g functions as a source electrode or a drain electrode of the transistor 3. The source or drain electrode of transistor 973 and the source or drain electrode of transistor 974 It functions as a drain electrode.

[0141] Next, an insulating film 918a is formed. Next, an insulating film 918b is formed. Next, an insulating film 91 An opening 938 is formed in the insulating film 918a and the insulating film 918b, reaching the conductive film 916a. An insulating film 918c is formed (see FIGS. 12A and 12B). 18a, the insulating film 918b, and the insulating film 918c are formed on the transistor 971 and the transistor 9 72, gate insulation of transistor 973, transistor 974 and transistor 975 It acts as a membrane.

[0142] Next, the insulating films 918a, 918b, and 918c are covered with a thin film of SiO 2 , which reaches the conductive film 916b. an opening 938b reaching the conductive film 916d; an opening 938c reaching the conductive film 916c; an opening 938d, an opening 938f reaching the conductive film 916g, and an opening 938f reaching the conductive film 916e; An opening 938g is formed. In addition, the insulating films 912a, 912b, and 918a are An opening 938a reaching the conductive film 904a is formed in the insulating film 918b and the insulating film 918c. (See Figures 13(A) and 13(B)).

[0143] Next, conductive films 914a and 914b, conductive films 914c and 914d are formed. The conductive film 914a is electrically connected to the conductive film 904a through the opening 938a. The conductive film 914b is electrically connected to the conductive film 916d through the opening 938c. Here, as described above, the conductive film 916d is electrically connected to the conductive film 904b. The conductive film 914b is electrically connected to the conductive film 904b. The conductive film 914d is electrically connected to the conductive film 904d through the opening 938e. 938f. 16g is electrically connected to the conductive film 904f. That is, the conductive film 914d is electrically connected to the conductive film 904f. The conductive film 914a functions as a gate electrode of the transistor 975. The conductive film 914b functions as one electrode of the capacitor 976. The conductive film 914c functions as gate electrodes of the transistors 971 and 973. The conductive film 914d functions as a gate electrode of the transistor 972.

[0144] Next, an insulating film 908 is formed. Next, an opening portion overlapping the opening portion 938b is formed in the insulating film 908. 948a, opening 948b overlapping opening 938g, and opening 938d overlapping opening 948b. 948c is formed (see FIG. 14(A) and FIG. 14(B)).

[0145] Next, the conductive film 926a, the conductive film 926b, and the conductive film 926c are formed. a is electrically connected to the conductive film 916c through the opening 948c. b is electrically connected to the conductive film 916b through the opening 948a. The conductive film 926c is electrically connected to the conductive film 916e through the opening 948b. The conductive film 926a functions as a signal line, and the conductive film 926c functions as a power supply line PL1.

[0146] Figures 14(A) and 14(B) correspond to Figures 6(B) and 6(C). The subsequent method for fabricating an EL display device is shown in FIGS.

[0147] An insulating film is formed on the insulating film 908, the conductive film 926a, the conductive film 926b, and the conductive film 926c. Next, an opening 958 is formed in the insulating film 928, reaching the conductive film 926b. (See FIG. 15(A) and FIG. 15(B)).

[0148] Next, the conductive film 934 is formed. The conductive film 934 is formed by contacting the conductive film 926b with the opening 958. (See FIGS. 15A and 15B.) The conductive film 934 is , which functions as one electrode of the light-emitting element 919 .

[0149] Next, a transparent film 932 having a function of transmitting or semi-transmitting visible light is formed (FIG. 16( See Figure 16(A) and Figure 16(B). By forming the transparent film 932, the resonance effect of light can be utilized. A micro-optical resonator (microcavity) structure can be formed, and the light can be extracted from the light-emitting element 919. The peak of the emitted light spectrum can be made sharp and intense. By including the film 932, the luminance and color purity of the EL display device can be improved. It is preferable that the thickness (number of layers) and type of the transparent film 932 be changed for each luminescent color of the pixel. However, the transparent film 932 does not necessarily have to be formed.

[0150] Next, an insulating film 936 is formed. The insulating film 936 has an opening 968 which becomes a light-emitting region of the pixel. (See FIGS. 16A and 16B.) The insulating film 936 functions as a partition wall. .

[0151] Next, the spacers 940 are formed (see FIGS. 16(A) and 16(B)).

[0152] Thereafter, a light-emitting layer, a conductive film that functions as the other electrode of the light-emitting element 919, and the like are formed. The EL display device can be manufactured with high definition and high display quality. It is a simple EL display device.

[0153] In the following, the gate voltage of the transistor 972 in the period T3 of the pixel shown in FIG. The Vgs value was calculated using an analog circuit simulator manufactured by SILVACO. SmartSpice, a simulator, and Clever, a high-precision 3D parasitic element extraction tool, are also included. Used.

[0154] First, the parasitic capacitance in the pixel was extracted using Clever. The thickness of each film is shown in Table 1 below.

[0155] [Table 1]

[0156] The extraction of the parasitic capacitance was performed until the error of the iterative calculation was within 5%. The D structure was set to MANHATTAN-TYPE in GEOMETRICAL MODE. The circuit size is a matrix of 3 pixels vertically and 3 pixels horizontally.

[0157] The value of the gate voltage Vgs of the transistor 972 in the period T3 of the pixel shown in FIG. The calculation is based on the difference Vdata between the potential Vdata of the signal line SL and the potential V0 of the power line PL2. -V0 is set to -1V (condition 1), -0.5V (condition 2), 0V (condition 3), 0.5V (condition 4), 1V (condition 5), and 1.5V (condition 6). The potential values ​​are: the potential Vano of the power supply line PL1 is 10 V, and the potential of the other electrode of the light emitting element 919 is Vcat was set to -4V, the potential GVDD was set to 15V, and the potential GVSS was set to -5V. VDD is the high level voltage supplied to the scanning lines GL1, GL2, and GL3, respectively. The potential GVSS corresponds to the potential of the scanning line GL1, the scanning line GL2, and the scanning line GL3. This corresponds to a low level potential applied to the line GL3.

[0158] In addition, the channel length L and channel width W of each transistor in the calculation are In transistor 1, the channel length L is 2 μm and the channel width W is 1.5 μm. The channel length L is 6 μm and the channel width W is 2 μm. m, the channel width W is 1.5 μm, the channel length L is 3 μm in the transistor 974, and the channel The channel width W is 1.5 μm, and the channel length L is 2 μm and the channel width W is 2 μm for the transistor 975. In all the transistors of the pixel shown in FIG. The region where the conductive film and the semiconductor film, which function as the gate or drain electrode, are in contact with each other, The length in the channel length direction in the area where the electrode is formed and the area where it overlaps is 0.75 μm. The value was m.

[0159] During the period T3, the gate voltage Vgs of the transistor 972 is Vdata-V0+Vth. Therefore, in the pixel shown in FIG. 6, Vgs-Vth=Vdata-V0. , Vgs-Vth ideally has a constant value regardless of the value of the threshold voltage Vth. He explained that:

[0160] FIG. 17 shows the Vgs-Vth and threshold voltages obtained by calculation under conditions 1 to 6. In FIG. 17, the horizontal axis represents the threshold voltage Vth (V) and the vertical axis represents Vgs -Vth(V). From FIG. 17, even when the value of the threshold voltage Vth changes, , the Vgs-Vth variation is smaller than when threshold voltage correction is not performed (see the dashed line in FIG. 17). It can be seen that the amount of heat is kept to around 45%.

[0161] From the above calculation results, in the EL display device according to one embodiment of the present invention, Even if variations or fluctuations occur in the threshold voltage Vth, the effect of these variations is reduced. It can be seen that the gate voltage Vgs of the capacitor 972 can be corrected.

[0162] <About the drive circuit> FIG. 22 illustrates an example of a scanning line driver circuit that can be used in a display device according to one embodiment of the present invention. In addition, a shift register (also referred to as G_SR), which is a component of the scanning line driving circuit, The terminal of the inverter (also written as G2_INV) connected to wire G2 and the terminal of wire G3 The terminal position of the inverter (also referred to as G3_INV) to be connected is shown in Figure 23(A), 23(B) and 23(C) are shown schematically, respectively.

[0163] 24 and 25 show circuits that can be used as the shift register shown in FIG. 23(A). 26 and 27, the circuit is 26 and 27, the second gate electrode may be provided in the first gate electrode. The second gate electrode is electrically connected to the first gate electrode. The transistor has a higher on-state current than a transistor of the same size that does not have a second gate electrode. Therefore, even if the voltage amplitude of the output signal is increased, the occupancy of the scanning line driving circuit is The area can be reduced. Also, Fig. 28(A) and Fig. 28(B) show the layout It can be used as an inverter connected to line G2 and an inverter connected to line G3. The diagram shows the circuitry that can be used to control the G_VDD, G_VCC1, and G_VCC2 high power supply voltages. Also, G_VSS, G_VEE1, G_VEE2 and G_VEE3 are low power supply voltages. The potential is shown.

[0164] The scanning line driving circuit shown in FIG. 22 is applied with the timing chart shown in FIG. 29. , can be made to work.

[0165] <About oxide semiconductor films> Among semiconductor films that can be used in one embodiment of the present invention, an oxide semiconductor film will be described below. I will explain.

[0166] The oxide semiconductor film is an oxide containing indium. When the element M is contained, the carrier mobility (electron mobility) increases. The element M is preferably, for example, aluminum, gallium, yttrium, or sulfur. The element M is, for example, an element that has a high bond energy with oxygen. For example, it is an element that has the function of increasing the energy gap of the oxide. The oxide semiconductor film preferably contains zinc. When the oxide contains zinc, for example, the oxide can be crystallized. The energy of the top of the valence band of an oxide varies depending on the ratio of the number of atoms of zinc, for example. can be controlled.

[0167] However, the oxide semiconductor film is not limited to an oxide containing indium. For example, Zn-Sn oxide or Ga-Sn oxide may be used.

[0168] The oxide semiconductor film is formed using an oxide having a large energy gap. The energy gap is, for example, 2.5 eV or more and 4.2 eV or less, preferably 2.8 eV. The voltage is preferably from 3 eV to 3.8 eV, more preferably from 3 eV to 3.5 eV.

[0169] When the oxide semiconductor film is formed by a sputtering method, the number of particles is reduced. It is preferable to use a target containing indium. Also, an oxide having a high atomic ratio of element M is preferable. When using a target, the conductivity of the target may be reduced. When a target is used, the conductivity of the target can be increased, and DC discharge and AC discharge can be used. This makes it easier to handle large-area substrates, and therefore improves the productivity of semiconductor devices. can be increased.

[0170] When an oxide semiconductor film is formed by a sputtering method, the atomic ratio of the target is In:M :Zn is 3:1:1, 3:1:2, 3:1:4, 1:1:0.5, 1:1:1, 1:1: 2, etc.

[0171] When an oxide semiconductor film is formed by sputtering, the atomic ratio of the target may be different from that of the target. In particular, zinc may form a film with a higher atomic ratio than the target. Specifically, the ratio of the number of atoms of zinc contained in the target to 4 may become smaller. It may be between 0 atomic% and 90 atomic%.

[0172] The influence of impurities in an oxide semiconductor film will be described below. In order to stabilize the electrical characteristics of the capacitor, it is necessary to reduce the impurity concentration in the oxide semiconductor film and to obtain a low-carrier It is effective to increase the carrier density and the purity of the oxide semiconductor film. , 1×10 17 pieces / cm 3 Less than 1×10 15 pieces / cm 3 Less than or equal to 1 x 10 13 pieces / cm 3 In order to reduce the impurity concentration in the oxide semiconductor film, It is also preferable to reduce the impurity concentration.

[0173] For example, silicon in an oxide semiconductor film can become a carrier trap or a carrier generation source. Therefore, the silicon concentration between the oxide semiconductor film and the adjacent insulating film is Secondary Ion Mass Spectroscopy (SIMS) 1×10 19 atoms / cm 3 Less than 5 x 10 1 8 atoms / cm 3 less than 2 × 10 18 atoms / cm 3 Less than do.

[0174] Furthermore, when hydrogen is contained in the oxide semiconductor film, the carrier density may increase. The hydrogen concentration of the oxide semiconductor film was measured by SIMS. 20 atoms / cm 3 Below Below, preferably 5 x 10 19 atoms / cm 3 Less than 1×10, more preferably 19 at oms / cm 3 Less than 5 × 10, more preferably 18 atoms / cm 3 The following applies. In addition, when nitrogen is contained in the oxide semiconductor film, the carrier density may increase. The nitrogen concentration of the oxide semiconductor film was 5×10 19 atoms / cm 3 Not yet less than 5 × 10 18 atoms / cm 3 Less than 1×10, more preferably 18 at oms / cm 3 Less than 5 × 10, more preferably 17 atoms / cm 3 The following applies.

[0175] In order to reduce the hydrogen concentration in the oxide semiconductor film, the hydrogen concentration in the adjacent insulating film is reduced. The hydrogen concentration of the adjacent insulating film is preferably 2×10 20 atoms / cm 3Less than or equal to 5 x 10 19 atoms / cm 3 Below, more preferably 1 x 1 0 19 atoms / cm 3 Less than 5 × 10, more preferably 18 atoms / cm 3 below In order to reduce the nitrogen concentration in the oxide semiconductor film, the nitrogen concentration in the adjacent insulating film is The nitrogen concentration of the adjacent insulating film is preferably reduced to 5×10 by SIMS. 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 The following is more preferred: 1×10 18 atoms / cm 3 Less than 5 × 10, more preferably 17 atoms / cm 3 The following applies.

[0176] The structure of the oxide semiconductor film will be described below.

[0177] Oxide semiconductor films are roughly classified into non-single-crystal oxide semiconductor films and single-crystal oxide semiconductor films. The single-crystal oxide semiconductor film is called CAAC-OS (C Axis Aligned Crystal Polycrystalline oxide semiconductor film The oxide semiconductor film includes a microcrystalline oxide semiconductor film, an amorphous oxide semiconductor film, and the like.

[0178] First, the CAAC-OS film will be described.

[0179] The CAAC-OS film is one of the oxide semiconductor films that has multiple crystal parts. The crystal part is small enough to fit inside a cube with a side length of less than 100 nm. The crystal part contained in the -OS film is a cubic crystal with a side length of less than 10 nm, less than 5 nm, or less than 3 nm. This includes cases where the size is small enough to fit inside the body.

[0180] The CAAC-OS film was observed under a transmission electron microscope (TEM). When observed under a crystalline microscope, clear boundaries between the crystals, i.e., crystal boundaries, are clearly visible. It is not possible to confirm the grain boundary. It can be said that the AC-OS film is less susceptible to the decrease in electron mobility caused by grain boundaries.

[0181] The CAAC-OS film was observed by TEM from a direction approximately parallel to the sample surface (cross-sectional TEM observation). This confirms that the metal atoms are arranged in layers in the crystalline region. Each layer is formed by reflecting the unevenness of the surface on which the CAAC-OS film is formed (also referred to as the surface on which the CAAC-OS film is formed) or the upper surface. The CAAC-OS film has a shape similar to that of the CAAC-OS film, and is arranged parallel to the surface on which the CAAC-OS film is formed or the upper surface of the CAAC-OS film.

[0182] On the other hand, the CAAC-OS film was observed by TEM from a direction almost perpendicular to the sample surface (planar TEM). When observed, metal atoms are arranged in triangular or hexagonal shapes in the crystals. However, there is no regularity in the arrangement of metal atoms between different crystal parts. .

[0183] Cross-sectional and planar TEM observations revealed that the crystals in the CAAC-OS film had an orientation. It turns out that there are.

[0184] X-ray diffraction (XRD) was performed on the CAAC-OS film. For example, a CAAC-OS film with InGaZnO4 crystals was found by structural analysis using the device. In the out-of-plane analysis, a peak was observed at a diffraction angle (2θ) of approximately 31°. This peak is attributed to the (009) plane of the InGaZnO4 crystal. Therefore, the crystals of the CAAC-OS film have a c-axis orientation, and the c-axis is approximately aligned on the surface on which the film is formed or on the upper surface. You can see that it is oriented vertically.

[0185] In this specification, when the crystal is a trigonal or rhombohedral crystal, it is expressed as a hexagonal crystal system. .

[0186] On the other hand, in-pla, X-rays are incident on the CAAC-OS film from a direction almost perpendicular to the c-axis. In the analysis by the NE method, a peak may appear at 2θ around 56°. This peak is It is attributed to the (110) plane of the InGaZnO4 crystal. InGaZnO4 single crystal oxide In the case of a semiconductor film, 2θ is fixed at around 56°, and the normal vector of the sample surface is set as the axis (φ axis). When the sample is rotated and analyzed (φ scan), the crystal plane equivalent to the (110) plane is obtained. In contrast, in the case of the CAAC-OS film, the 2θ is set to 56 Even when φ is fixed at around 10° and scanned, no clear peak appears.

[0187] From the above, it is concluded that the a-axis and b-axis orientations are inconsistent between different crystal regions in the CAAC-OS film. Although it is regular, it has a c-axis orientation, and the c-axis is parallel to the normal vector of the surface to be formed or the upper surface. Therefore, the layered structure confirmed by the cross-sectional TEM observation mentioned above is consistent with the Each layer of metal atoms arranged in a plane parallel to the ab plane of the crystal.

[0188] The crystalline part is formed when the CAAC-OS film is formed or when a crystallization process such as a heat treatment is performed. As described above, the c-axis of the crystal is aligned with the surface on which the CAAC-OS film is formed or the surface on which the CAAC-OS film is formed. is oriented in a direction parallel to the normal vector of the top surface. When the shape of the CAAC-OS film is changed by etching, the c-axis of the crystal is aligned with the shape of the CAAC-OS film. It may not be parallel to the normal vector of the top or bottom surface.

[0189] The crystallinity of the CAAC-OS film may not be uniform. When the crystal part of the CAAC-OS film is formed by crystal growth from the vicinity of the top surface, The area near the surface may have a higher degree of crystallinity than the area near the surface to be formed. When impurities are added to a C-OS film, the crystallinity of the region where the impurities are added changes, resulting in partial In some cases, regions of different crystallinity may be formed.

[0190] In addition, the out-of-plane method of CAAC-OS film with InGaZnO4 crystals In the analysis by , in addition to the peak at 2θ around 31°, a peak also appeared at 2θ around 36°. The peak at 2θ around 36° is due to the presence of c-axis orientation in part of the CAAC-OS film. The CAAC-OS film contains crystals that do not have a 2θ of around 31°. It is preferable that the peak is exhibited at 2θ of around 36° and that the peak is not exhibited at 2θ of around 36°.

[0191] The CAAC-OS film is an oxide semiconductor film with a low concentration of impurities. These are elements other than the main components of the oxide semiconductor film, such as silicon and transition metal elements. The elements that bond to oxygen more strongly than the metal elements that constitute the oxide semiconductor film, such as fluorine, By removing oxygen from the oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disrupted, reducing its crystallinity. In addition, heavy metals such as iron and nickel, argon, and carbon dioxide have an atomic radius (or molecular radius) is large, and when it is contained inside the oxide semiconductor film, The impurities contained in the oxide semiconductor film are likely to disturb the atomic arrangement and cause a decrease in crystallinity. Objects can act as carrier traps or carrier sources.

[0192] The CAAC-OS film is an oxide semiconductor film with a low density of defect states. Oxygen vacancies in the semiconductor film can become carrier traps or trap hydrogen, It can be a source of carrier generation.

[0193] Low impurity concentration and low defect level density (low oxygen vacancies) are called high purity intrinsic or The term "substantially highly purified intrinsic" refers to a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film. Since there are fewer carrier generation sources, the carrier density can be reduced. The transistor using the oxide semiconductor film has electrical characteristics ( It is also called normally-on.) It is rare for it to become a high-purity intrinsic or substantially high-purity The intrinsic oxide semiconductor film has few carrier traps. Transistors using this film have little fluctuation in electrical characteristics and are highly reliable. Note that it takes time for the charges trapped in the carrier traps in the oxide semiconductor film to be released. The impurity concentration is high and the charge is stable for a long time, so the charge may behave like a fixed charge. Therefore, a transistor using an oxide semiconductor film with a high density of defect states has unstable electrical characteristics. This may occur.

[0194] In addition, transistors using CAAC-OS films show improved electrical characteristics when irradiated with visible light or ultraviolet light. The fluctuation is small.

[0195] Next, a microcrystalline oxide semiconductor film will be described.

[0196] In the microcrystalline oxide semiconductor film, crystal parts can be clearly seen in the TEM image. The crystal part contained in the microcrystalline oxide semiconductor film may have a size of 1 nm or more and 100 nm or less. , or 1 nm to 10 nm in size. Nanocrystals (nc) are microcrystals of 1 nm or less and 3 nm or less. The oxide semiconductor film having nc-OS (nanocrystalline Oxide Semiconductor Film) The nc-OS film is called a TE film. In the M observation image, the grain boundaries may not be clearly visible.

[0197] The nc-OS film is a microscopic region (e.g., a region of 1 nm to 10 nm, especially a region of 1 nm or more). The nc-OS film has a periodic atomic arrangement in the region of 3 nm or less. There is no regularity in the crystal orientation between the crystal parts. Therefore, no orientation is observed overall. Therefore, the nc-OS film cannot be distinguished from an amorphous oxide semiconductor film depending on the analysis method. For example, XRD, which uses X-rays with a diameter larger than that of the crystal part, is used for nc-OS films. When structural analysis is performed using the device, the crystal plane is analyzed using the out-of-plane method. In addition, the nc-OS film has a larger probe diameter (e.g., Electron beam diffraction (also called selected area electron beam diffraction) is performed using an electron beam with a diameter of 50 nm or more. On the other hand, for the nc-OS film, Probe diameter close to or smaller than the size of the crystal part (for example, 1 nm to 30 nm) When electron beam diffraction (also called nanobeam electron beam diffraction) is performed using an electron beam of Furthermore, when nanobeam electron diffraction is performed on the nc-OS film, a circular pattern is observed. In some cases, bright areas (ring-shaped) are observed. When performing beam electron diffraction, multiple spots may be observed within a ring-shaped region. .

[0198] The nc-OS film is an oxide semiconductor film with higher order than an amorphous oxide semiconductor film. Therefore, the nc-OS film has a lower density of defect states than the amorphous oxide semiconductor film. In the nc-OS film, there is no regularity in the crystal orientation between different crystal parts. The S film has a higher defect state density than the CAAC-OS film.

[0199] The oxide semiconductor film may be, for example, an amorphous oxide semiconductor film, a microcrystalline oxide semiconductor film, or a CA Two or more types of AC-OS films may be used.

[0200] The oxide semiconductor film may be a stacked film of oxide semiconductor films. For example, the oxide semiconductor film may be , a two-layer structure, or a three-layer structure may also be used.

[0201] For example, a case where the oxide semiconductor film has a three-layer structure will be described.

[0202] For the second layer (middle layer), refer to the description of the oxide semiconductor film. The third layer (upper layer) is made up of one or more elements other than oxygen, which is the same as the second layer. The second layer is an oxide semiconductor film composed of one or more elements other than oxygen. The first and third layers are composed of more than one species, so the interface between the first and second layers and the second layer Interface states are unlikely to form at the interface between the first and third layers.

[0203] When the first layer is an In-M-Zn oxide, the sum of In and M is 100 atomic %. When the atomic percentage of In is less than 50%, the atomic percentage of M is preferably more than 50%. More preferably, In is less than 25 atomic % and M is more than 75 atomic %. In addition, when the second layer is an In-M-Zn oxide, the sum of In and M is 100 atoms. When the atomic percentage is ic%, preferably In is higher than 25 atomic % and M is 75 atomic %. c%, more preferably In is higher than 34 atomic % and M is 66 atomic % When the third layer is an In-M-Zn oxide, the sum of In and M is less than 100%. atomic %, In is less than 50 atomic % and M is more than 50 atomic %. More preferably, In is less than 25 atomic % and M is more than 75 atomic %. The third layer may be made of the same oxide as the first layer.

[0204] Here, there may be a mixed region of the first and second layers between the first and second layers. In addition, there may be a mixed region of the second and third layers between the second and third layers. The interface state density is low in the overlap region. , the energy changes continuously near each interface (also called continuous junction). It has a band structure.

[0205] The second layer is made of an oxide with a higher electron affinity than the first and third layers. As a target, the electron affinity of the first and third layers is preferably 0.07 eV or more and 1.3 eV or less. Preferably, it is 0.1 eV or more and 0.7 eV or less, and more preferably, it is 0.15 eV or more and 0.4 eV or less. The electron affinity is calculated by the relationship between the vacuum level and the energy at the bottom of the conduction band. This is the difference.

[0206] When an electric field is applied to the gate electrode, the electron affinity of the first, second, and third layers is A channel is formed in the second layer where the density is large.

[0207] In addition, to increase the on-current of the transistor, it is preferable that the thickness of the third layer is as small as possible. For example, the third layer is less than 10 nm, preferably 5 nm or less, and more preferably 3 nm. On the other hand, the third layer is an insulating film that is adjacent to the second layer where the channel is formed. It has the function of blocking elements other than oxygen (such as silicon) from entering. Therefore, it is preferable that the third layer has a certain thickness. For example, the thickness of the third layer is 0 It is 0.3 nm or more, preferably 1 nm or more, and more preferably 2 nm or more.

[0208] In order to improve reliability, it is preferable that the first layer is thick and the third layer is thin. The thickness of the first layer is 20 nm or more, preferably 30 nm or more, and more preferably 40 nm or more. The thickness of the first layer is 20 nm or more, preferably 60 nm or more. The thickness is preferably 30 nm or more, more preferably 40 nm or more, and even more preferably 60 nm or more. The distance from the interface between the adjacent insulating film and the first layer to the second layer where the channel is formed is 20 nm. or more, preferably 30 nm or more, more preferably 40 nm or more, and even more preferably 60 nm or more However, since this may decrease the productivity of semiconductor devices, The mesh thickness is 200 nm or less, preferably 120 nm or less, and more preferably 80 nm or less. Below.

[0209] For example, the silicon concentration between the first and second layers is 1×10 1 9 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than or even better Preferably 2 x 10 18 atoms / cm 3 In addition, between the second and third layers, The silicon concentration in the sample was measured by SIMS at 1×10 19 atoms / cm 3 Less than, preferred Kuha 5 x 10 18 atoms / cm 3 less than 2 × 10 18 atoms / cm 3 Less than.

[0210] In addition, in order to reduce the hydrogen concentration in the second layer, the hydrogen concentrations in the first and third layers were reduced. The hydrogen concentration of the first and third layers is preferably 2×10 20 atoms / cm 3 Less than or equal to 5 x 10 19 atoms / cm 3 Below, more preferably 1 x 1 0 19 atoms / cm 3 Less than 5 × 10, more preferably 18 atoms / cm 3 below In addition, in order to reduce the nitrogen concentration in the second layer, the nitrogen concentrations in the first and third layers are reduced. The nitrogen concentration in the first and third layers is preferably 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 The following is more preferred: 1×10 18 atoms / cm 3 Less than 5 × 10, more preferably 17 atoms / cm 3 The following applies.

[0211] The three-layer structure described above is an example. For example, a two-layer structure without the first or third layer may also be used. do not have.

[0212] <module> A display module to which the semiconductor device of one embodiment of the present invention is applied will be described below with reference to FIG. Explanations will be given.

[0213] The display module 8000 shown in FIG. 18 is made up of an upper cover 8001 and a lower cover 8002. In between, touch panel 8004 connected to FPC8003, and touch panel 8005 connected to FPC8005 Display panel 8006, backlight unit 8007, frame 8009, printed circuit board 8010 and a battery 8011. The device may not have the memory 8011, the touch panel 8004, etc.

[0214] The semiconductor device of one embodiment of the present invention can be used for the display panel 8006, for example.

[0215] The upper cover 8001 and the lower cover 8002 are connected to the touch panel 8004 and the display panel. The shape and dimensions can be changed as needed to fit the size of the 8006.

[0216] The touch panel 8004 is a resistive or capacitive touch panel. 8006. In addition, the opposing substrate (sealing substrate) of the display panel 8006 ) can also be equipped with a touch panel function. It is also possible to provide an optical sensor in each pixel of the touch panel to make it an optical touch panel. Alternatively, a touch sensor electrode may be provided in each pixel of the display panel 8006, and a capacitive touch sensor may be used. It is also possible to use it as a chip panel.

[0217] The backlight unit 8007 includes a light source 8008. It may be provided at the end of the unit 8007 and configured to use a light diffusion plate.

[0218] The frame 8009 protects the display panel 8006 and also prevents the operation of the printed circuit board 8010. It may also have a function as an electromagnetic shield to block electromagnetic waves generated by the The frame 8009 may also function as a heat sink.

[0219] The printed circuit board 8010 includes a power supply circuit, a signal circuit for outputting a video signal, and a clock signal. The power supply circuit is provided with a signal processing circuit. Alternatively, the power source may be a battery 8011 provided separately. In this case, the battery 8011 may not be required.

[0220] In addition, the display module 8000 includes components such as a polarizing plate, a retardation plate, and a prism sheet. It may also be provided in addition.

[0221] <Electronic equipment> Examples of electronic devices and lighting devices to which the display device of one embodiment of the present invention is applied will be described below with reference to drawings. This will be explained with reference to the surface.

[0222] As an example of an electronic device to which a display device having a flexible shape is applied, a television equipment (also called televisions or television receivers), monitors, displays, etc. for computers Digital cameras, digital video cameras, digital photo frames, mobile information terminals (mobile phones) (also called mobile phone devices), portable game machines, personal digital assistants, sound reproducing devices, pachinko machines Examples include large game consoles such as Nintendo DS.

[0223] In addition, lighting devices and display devices can be installed on the interior or exterior walls of houses and buildings, or on the interior or exterior of automobiles. It is also possible to incorporate it along the curved surface of the

[0224] 19A shows an example of a portable information terminal. The portable information terminal 7400 is a housing 74 In addition to the display unit 7402 incorporated in the 01, there are operation buttons 7403 and an external connection port 7404 , a speaker 7405, a microphone 7406, etc. The LCD panel is manufactured by using a display device as the display portion 7402.

[0225] In the portable information terminal 7400 shown in FIG. 19A, when the display portion 7402 is touched with a finger or the like, You can also make calls, enter text, and perform any other functions. The operation can be performed by touching the display portion 7402 with a finger or the like.

[0226] Also, by operating the operation button 7403, the power can be turned on and off, and the display unit 7402 can be displayed. For example, from the email creation screen, you can change the type of image displayed. - You can switch to the screen.

[0227] Here, the display device of one embodiment of the present invention is incorporated in the display portion 7402. As a result, a highly reliable portable information terminal can be provided with a curved display section.

[0228] FIG. 19B shows an example of a wristband-type display device. The device includes a housing 7101, a display unit 7102, operation buttons 7103, and a transmitting / receiving device 7104. Prepare.

[0229] The portable display device 7100 can receive a video signal by the transmitting / receiving device 7104. Video can be displayed on the display unit 7102. Audio signals can also be transmitted to other receiving devices. It is also possible to do so.

[0230] In addition, the operation button 7103 can be used to turn the power on and off and to switch the displayed image. , or adjust the volume of the audio.

[0231] Here, the display device of one embodiment of the present invention is incorporated in the display portion 7102. As a result, a highly reliable portable display device can be provided that has a curved display portion.

[0232] 19(C) and 19(D) show an example of a lighting device. The lighting device 7220 includes a base 7201 having an operation switch 7203 and a base 720 It has a light-emitting part supported by 1.

[0233] The light-emitting portion 7212 of the lighting device 7210 shown in FIG. 19(C) has two convexly curved The light emitting units are arranged symmetrically. It can illuminate the direction.

[0234] The lighting device 7220 shown in FIG. 19(D) includes a light-emitting portion 7222 that is curved in a concave shape. Therefore, in order to collect light emitted from the light emitting portion 7222 onto the front surface of the lighting device 7220, It is suitable for brightly lighting an area.

[0235] Furthermore, the light-emitting units of the lighting device 7210 and the lighting device 7220 are flexible. Therefore, the light emitting part is fixed with a member such as a plastic member or a movable frame, and The light emitting surface of the light emitting portion may be configured to be freely curved according to the application.

[0236] Here, the light emitting units of the lighting device 7210 and the lighting device 7220 are each provided with the The display device of one embodiment is incorporated. Therefore, the display device has a curved display portion and is reliable. It can be a highly efficient lighting device.

[0237] An example of a portable display device is shown in FIG. 20A. The display device 7300 includes a housing 7301, It includes a display unit 7302, an operation button 7303, a drawer member 7304, and a control unit 7305. .

[0238] The display device 7300 is a flexible display unit rolled up in a cylindrical housing 7301. The display portion 7302 includes a first substrate on which a light-shielding layer and the like are formed, and a transistor. The display portion 7302 is disposed in the housing 7301. It is always wrapped so that the second substrate is on the outside.

[0239] The display device 7300 can receive a video signal through the control unit 7305. The control unit 7305 is provided with a battery. In addition, the control unit 7305 is equipped with a connector, and is configured to directly supply video signals and power. That's fine.

[0240] In addition, the operation button 7303 can be used to turn the power on and off and to switch the displayed image. etc. can be done.

[0241] FIG. 20B shows a state in which the display portion 7302 is pulled out by a pull-out member 7304 . In this state, an image can be displayed on the display portion 7302. The provided operation button 7303 allows for easy operation with one hand.

[0242] In order to prevent the display portion 7302 from bending when the display portion 7302 is pulled out, A frame for reinforcement may be provided at the end of 2.

[0243] In addition to this configuration, a speaker is provided on the housing, and the audio signal received together with the video signal is output. The configuration may be such that sound is output.

[0244] The display device of one embodiment of the present invention is incorporated in the display portion 7302. Since the unit 7302 is a flexible and reliable display device, the display device 7300 A lightweight and highly reliable display device can be obtained.

[0245] Note that the display device of one embodiment of the present invention can be used in the electronic devices and lighting devices described above. It goes without saying that there is no particular limitation.

[0246] The configurations and methods shown in the embodiments may be used in conjunction with other configurations and methods shown in the embodiments. They can be used in any suitable combination. [Example]

[0247] In this example, an EL display device according to one embodiment of the present invention was manufactured.

[0248] Table 2 shows the specifications of the EL display device.

[0249] [Table 2]

[0250] The EL display device according to one embodiment of the present invention has a display area of ​​13.3 inches, and can display nearly 500 million pixels. It also has a high aperture ratio of over 40%.

[0251] The EL display device has the scanning line driving circuit shown in FIG. The positions of the inverter terminals connected to wire G3 and the inverter terminals connected to wire G4 are shown in Figure 23 ( 23(A), 23(B) and 23(C), respectively. The shift register shown in FIG. 26 was used as a component of the operating circuit.

[0252] Figure 30 shows the output waveform of the scanning line driver circuit. The clock frequency indicated by GCK1 is 64. At this time, the amplitude voltage of the output signal on the wiring G1 was approximately 20V. That is, the EL display device manufactured in this example can sufficiently connect the wiring G1 even during a short selection period. You can see that it is charging.

[0253] Figure 21 shows a photograph of the EL display device. Figure 31 shows the color coordinates of each RGB color of the EL display device. From Figure 31, we can see that the NTSC ratio is higher than 84%. 31, the EL display device fabricated in this example has a high density of elements, but It can be seen that it has high display quality. [Explanation of symbols]

[0254] 100 boards 104 Conductive film 112 insulating film 114 Conductive film 116 Conductive film 118 insulating film 700 boards 704a Conductive film 704b Conductive film 706 Semiconductor Film 707 Semiconductor Film 712a Insulating film 712b insulating film 714a Conductive film 714b Conductive film 716a Conductive film 716b Conductive film 718a Insulating film 718b insulating film 718c insulating film 719 Light-emitting element 720 insulating film 721 Insulating film 731 terminal 732 FPC 733a wiring 734 Sealing material 735 Drive Circuit 736 Drive Circuit 737 pixels 741 Transistor 742 Capacitor 743 Switching Elements 744 signal line 750 board 751 Transistor 752 Capacitor 753 Liquid crystal elements 754 scan lines 755 signal line 781 Conductive Film 782 luminescent layer 783 Conductive Film 784 Bulkhead 791 Conductive Film 792 insulating film 793 Liquid Crystal Layer 794 insulating film 795 Spacer 796 Conductive Film 797 Circuit Board 900 boards 904a Conductive film 904b Conductive film 904c conductive film 904d Conductive film 904e conductive film 904f conductive film 906 Semiconductor Film 906a Semiconductor film 906b Semiconductor film 906c Semiconductor film 906d Semiconductor film 908 Insulating film 912a Insulating film 912b insulating film 914a Conductive film 914b Conductive film 914c conductive film 914d Conductive film 916a Conductive film 916b Conductive film 916c Conductive film 916d Conductive film 916e Conductive film 916f Conductive film 916g Conductive film 918a Insulating film 918b insulating film 918c insulating film 919 Light-emitting element 926a Conductive film 926b Conductive film 926c conductive film 928 Insulating Film 928a opening 928b opening 928c opening 932 Transparent membrane 934 Conductive film 936 Insulating Film 938 Opening 938a opening 938b opening 938c opening 938d opening 938e opening 938f opening 938g opening 940 Spacer 948a opening 948b opening 948c opening 958 Opening 968 Opening 971 Transistor 972 transistors 973 Transistors 974 transistors 975 transistors 976 Capacitor 7100 Portable display devices 7101 Housing 7102 Display section 7103 Operation button 7104 Transmitting and receiving equipment 7201 Daibu 7203 Operation switch 7210 Lighting equipment 7212 Light-emitting part 7220 Lighting equipment 7222 Light-emitting part 7300 display device 7301 Housing 7302 Display section 7303 Operation button 7304 Materials 7305 Control Unit 7400 Mobile Information Terminal 7401 Housing 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 8000 Display Module 8001 Top cover 8002 Lower cover 8003 FPC 8004 Touch Panel 8005 FPC 8006 Display Panel 8007 Backlight Unit 8008 light source 8009 Frame 8010 Printed Circuit Board 8011 Battery

Claims

1. a pixel includes first to fifth transistors, a light-emitting element, a first wiring, a second wiring, and a third wiring; one of a source electrode and a drain electrode of the first transistor is electrically connected to the first wiring to which an image signal is input; one of a source electrode or a drain electrode of the second transistor is electrically connected to one of a source electrode or a drain electrode of the third transistor; one of a source electrode and a drain electrode of the fourth transistor is electrically connected to a gate electrode of the second transistor; the fourth transistor has a function of inputting the image signal to a gate electrode of the second transistor through at least a channel formation region of the fourth transistor; one of a source electrode and a drain electrode of the fifth transistor is electrically connected to a gate electrode of the second transistor; the other of the source electrode and the drain electrode of the fifth transistor is electrically connected to the second wiring; the other of the source electrode and the drain electrode of the third transistor is electrically connected to a pixel electrode of the light-emitting element; a light-emitting device having a function of controlling a current supplied to the light-emitting element in accordance with a potential of a gate electrode of the second transistor when the third wiring is electrically connected to a pixel electrode of the light-emitting element through at least a channel formation region of the second transistor and a channel formation region of the third transistor; a semiconductor film having a channel formation region of the third transistor; a first conductive film having a region disposed above the semiconductor film and functioning as one of a source electrode and a drain electrode of the third transistor; a second conductive film having a region disposed above the semiconductor film and functioning as the other of the source electrode and the drain electrode of the third transistor; a third conductive film having a region disposed above the semiconductor film and functioning as a gate electrode of the third transistor; a first insulating film having a region disposed above the first conductive film, a region disposed above the second conductive film, and a region disposed above the third conductive film; a fourth conductive film having a region in contact with an upper surface of the first insulating film and functioning as the first wiring; a fifth conductive film having a region in contact with an upper surface of the first insulating film and functioning as the third wiring; a sixth conductive film having a region in contact with an upper surface of the first insulating film and electrically connected to the second conductive film; a second insulating film having a region disposed above the fourth conductive film, a region disposed above the fifth conductive film, and a region disposed above the sixth conductive film; a seventh conductive film having a region disposed above the second insulating film, electrically connected to the sixth conductive film, and functioning as the pixel electrode; Light-emitting device.

2. a pixel includes first to fifth transistors, a light-emitting element, a first wiring, a second wiring, and a third wiring; one of a source electrode and a drain electrode of the first transistor is electrically connected to the first wiring to which an image signal is input; one of a source electrode or a drain electrode of the second transistor is electrically connected to one of a source electrode or a drain electrode of the third transistor; one of a source electrode and a drain electrode of the fourth transistor is electrically connected to a gate electrode of the second transistor; the fourth transistor has a function of inputting the image signal to a gate electrode of the second transistor through at least a channel formation region of the fourth transistor; one of a source electrode and a drain electrode of the fifth transistor is electrically connected to a gate electrode of the second transistor; the other of the source electrode and the drain electrode of the fifth transistor is electrically connected to the second wiring; the other of the source electrode and the drain electrode of the third transistor is electrically connected to a pixel electrode of the light-emitting element; a light-emitting device having a function of controlling a current supplied to the light-emitting element in accordance with a potential of a gate electrode of the second transistor when the third wiring is electrically connected to a pixel electrode of the light-emitting element through at least a channel formation region of the second transistor and a channel formation region of the third transistor; a semiconductor film having a channel formation region of the third transistor; a first conductive film having a region disposed above the semiconductor film and functioning as one of a source electrode and a drain electrode of the third transistor; a second conductive film having a region disposed above the semiconductor film and functioning as the other of the source electrode and the drain electrode of the third transistor; a third conductive film having a region disposed above the semiconductor film and functioning as a gate electrode of the third transistor; a first insulating film having a region disposed above the first conductive film, a region disposed above the second conductive film, and a region disposed above the third conductive film; a fourth conductive film having a region in contact with an upper surface of the first insulating film and functioning as the first wiring; a fifth conductive film having a region in contact with an upper surface of the first insulating film and functioning as the third wiring; a sixth conductive film having a region in contact with an upper surface of the first insulating film and electrically connected to the second conductive film; a second insulating film having a region disposed above the fourth conductive film, a region disposed above the fifth conductive film, and a region disposed above the sixth conductive film; a seventh conductive film having a region disposed above the second insulating film, electrically connected to the sixth conductive film, and functioning as the pixel electrode; the fourth conductive film has a region disposed above an eighth conductive film having a function as the second wiring, the fifth conductive film has a region disposed above the eighth conductive film; Light-emitting device.

3. a pixel includes first to fifth transistors, a light-emitting element, a first wiring, a second wiring, and a third wiring; one of a source electrode and a drain electrode of the first transistor is electrically connected to the first wiring to which an image signal is input; one of a source electrode or a drain electrode of the second transistor is electrically connected to one of a source electrode or a drain electrode of the third transistor; one of a source electrode and a drain electrode of the fourth transistor is electrically connected to a gate electrode of the second transistor; the fourth transistor has a function of inputting the image signal to a gate electrode of the second transistor through at least a channel formation region of the fourth transistor; one of a source electrode and a drain electrode of the fifth transistor is electrically connected to a gate electrode of the second transistor; the other of the source electrode and the drain electrode of the fifth transistor is electrically connected to the second wiring; the other of the source electrode and the drain electrode of the third transistor is electrically connected to a pixel electrode of the light-emitting element; a light-emitting device having a function of controlling a current supplied to the light-emitting element in accordance with a potential of a gate electrode of the second transistor when the third wiring is electrically connected to a pixel electrode of the light-emitting element through at least a channel formation region of the second transistor and a channel formation region of the third transistor; a semiconductor film having a channel formation region of the third transistor; a first conductive film having a region disposed above the semiconductor film and functioning as one of a source electrode and a drain electrode of the third transistor; a second conductive film having a region disposed above the semiconductor film, the second conductive film functioning as one of a source electrode and a drain electrode of the second transistor, and the second conductive film functioning as the other of a source electrode and a drain electrode of the third transistor; a third conductive film having a region disposed above the semiconductor film and functioning as a gate electrode of the third transistor; a first insulating film having a region disposed above the first conductive film, a region disposed above the second conductive film, and a region disposed above the third conductive film; a fourth conductive film having a region in contact with an upper surface of the first insulating film and functioning as the first wiring; a fifth conductive film having a region in contact with an upper surface of the first insulating film and functioning as the third wiring; a sixth conductive film having a region in contact with an upper surface of the first insulating film and electrically connected to the second conductive film; a second insulating film having a region disposed above the fourth conductive film, a region disposed above the fifth conductive film, and a region disposed above the sixth conductive film; a seventh conductive film having a region disposed above the second insulating film, electrically connected to the sixth conductive film, and functioning as the pixel electrode; Light-emitting device.

4. a pixel includes first to fifth transistors, a light-emitting element, a first wiring, a second wiring, and a third wiring; one of a source electrode and a drain electrode of the first transistor is electrically connected to the first wiring to which an image signal is input; one of a source electrode or a drain electrode of the second transistor is electrically connected to one of a source electrode or a drain electrode of the third transistor; one of a source electrode and a drain electrode of the fourth transistor is electrically connected to a gate electrode of the second transistor; the fourth transistor has a function of inputting the image signal to a gate electrode of the second transistor through at least a channel formation region of the fourth transistor; one of a source electrode and a drain electrode of the fifth transistor is electrically connected to a gate electrode of the second transistor; the other of the source electrode and the drain electrode of the fifth transistor is electrically connected to the second wiring; the other of the source electrode and the drain electrode of the third transistor is electrically connected to a pixel electrode of the light-emitting element; a light-emitting device having a function of controlling a current supplied to the light-emitting element in accordance with a potential of a gate electrode of the second transistor when the third wiring is electrically connected to a pixel electrode of the light-emitting element through at least a channel formation region of the second transistor and a channel formation region of the third transistor; a semiconductor film having a channel formation region of the third transistor; a first conductive film having a region disposed above the semiconductor film and functioning as one of a source electrode and a drain electrode of the third transistor; a second conductive film having a region disposed above the semiconductor film, the second conductive film functioning as one of a source electrode and a drain electrode of the second transistor, and the second conductive film functioning as the other of a source electrode and a drain electrode of the third transistor; a third conductive film having a region disposed above the semiconductor film and functioning as a gate electrode of the third transistor; a first insulating film having a region disposed above the first conductive film, a region disposed above the second conductive film, and a region disposed above the third conductive film; a fourth conductive film having a region in contact with an upper surface of the first insulating film and functioning as the first wiring; a fifth conductive film having a region in contact with an upper surface of the first insulating film and functioning as the third wiring; a sixth conductive film having a region in contact with an upper surface of the first insulating film and electrically connected to the second conductive film; a second insulating film having a region disposed above the fourth conductive film, a region disposed above the fifth conductive film, and a region disposed above the sixth conductive film; a seventh conductive film having a region disposed above the second insulating film, electrically connected to the sixth conductive film, and functioning as the pixel electrode; the fourth conductive film has a region disposed above an eighth conductive film having a function as the second wiring, the fifth conductive film has a region disposed above the eighth conductive film; Light-emitting device.

Images