Indication device

Abstract

To simplify a manufacturing process of a thin film transistor that is mounted on an EL display device.SOLUTION: A thin film transistor is manufactured as follows: a first conductive film, an insulating film, a semiconductor film, an impurity semiconductor film, and a second conductive film are stacked; a first resist mask is formed thereover; a thin-film stack body is formed by performing a first etching; a gate electrode layer is formed by performing a second etching including side etching to the thin-film stack body; and then a source electrode and a drain electrode layer and the like are formed using a second resist mask. By using this thin film transistor, an EL display device is manufactured.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This invention relates to a method for fabricating an EL display device having thin-film transistors. [Background technology]

[0002] In recent years, a thickness of several nanometers to several hundred nanometers has been formed on a substrate having an insulating surface such as a glass substrate. Thin-film transistors, which are composed of semiconductor thin films of a certain thickness, are attracting attention. The company is involved in the development of integrated circuits (ICs) and electro-optical devices, among other electrical components. It is widely used in sub-devices. Thin-film transistors are particularly used in liquid crystal display devices or EL(E) Image display devices such as lectroluminescence display devices. Development as a wetting element is being expedited.

[0003] In an active-matrix EL display device, the light-emitting element provided within the selected pixel A voltage is applied between one electrode and the other electrode, which, together with the first electrode, sandwiches the EL layer. This causes current to flow through the EL layer, making the light-emitting layer emit light. This light emission is then viewed as a display pattern. It is recognized by the observer. Note that here, an active matrix type EL display device is a matrix By driving pixels arranged in a spiral pattern with switching elements, a display pattern is created on the screen. This refers to an EL display device that employs a method for forming turns.

[0004] The applications of active-matrix EL display devices are expanding, with increasing screen area size. There is a growing demand for higher resolution and higher aperture ratios. Also, active-matrix EL displays... The equipment requires high reliability, and the production method requires high productivity and reduced production costs. One way to increase productivity and reduce production costs is to simplify the process. ru.

[0005] In active-matrix EL display devices, thin-film transients are mainly used as switching elements. A stan is used. It is used in photolithography in the fabrication of thin-film transistors. Reducing the number of photomasks is important for simplifying the process. For example, photo When one mask is added, processes such as resist coating, pre-baking, exposure, development, and post-baking are performed. During this process, and in the processes before and after it, the film formation and etching processes, and furthermore, the resist removal process, Washing and drying processes will be required. Therefore, one additional photomask will be needed in the manufacturing process. Simply adding this significantly increases the number of steps. Therefore, the photomask in the manufacturing process is reduced. Numerous technological developments are being undertaken to reduce it.

[0006] Thin-film transistors have a top gate where the channel formation region is located below the gate electrode. They are broadly classified into two types: the T-type and the bottom-gate type, in which the channel formation region is located above the gate electrode. The number of photomasks used in the fabrication process of bottom-gate thin-film transistors. This refers to the number of photomasks used in the fabrication process of top-gate thin-film transistors. It is known that there are fewer than three photons. Bottom-gate thin-film transistors use three photons. It is generally made by squirting.

[0007] Conventional techniques for reducing the number of photomasks include back-illumination, registry flow, and Many of these methods employ complex techniques such as the lift-off method and require specialized equipment. There are many. Using such complex technology leads to various problems, and yield... There has been concern about a decrease or the like. Also, it is often inevitable to sacrifice the electrical characteristics of the thin film transistor.

[0008] As a typical means for reducing the number of photomasks in the manufacturing process of thin film transistors, a technique using a multi-tone mask (referred to as a halftone mask or a grayscale mask) is widely known. As a technique for reducing the manufacturing process using a multi-tone mask, for example, Patent Document 1 can be cited.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, even in the case of manufacturing a bottom gate type thin film transistor using the above-described multi-tone mask, at least two photomasks are required, and it is difficult to further reduce the number of photomasks. One of these is used for patterning the gate electrode layer.

[0011] Here, an aspect of the present invention is to provide a new method capable of manufacturing a thin film transistor without newly using a photomask for patterning the gate electrode layer. That is, a method for manufacturing a thin film transistor is disclosed that does not require the use of complex techniques and can be created with even one photomask.

[0012] ​​​​​​​​This allows for a reduction in the number of photomasks used in the fabrication of thin-film transistors compared to conventional methods. This can also be reduced.

[0013] Furthermore, a thin-film transistor according to one aspect of the present invention is particularly used in pixels of an EL display device. One aspect of the present invention relates to the fabrication of an EL display device without using complex techniques. The challenge is to reduce the number of photomasks used in photoristortion compared to conventional methods. Furthermore, one aspect of the present invention aims to simplify the manufacturing process of EL display devices. [Means for solving the problem]

[0014] In a method for fabricating a thin-film transistor according to one aspect of the present invention, a first conductive film and the first conductive Thin film layer in which an insulating film, a semiconductor film, an impurity semiconductor film, and a second conductive film are stacked in this order on an electrical film. A layer is formed, and the first conductive film is exposed by the first etching, at least The pattern of the thin film laminate is formed by the second etching, and the pattern of the first conductive film is formed by the second etching. This forms the first conductive film. Here, the second etching is performed under conditions in which the first conductive film is side-etched. This will be done by [method].

[0015] Here, the first etching can be done using either dry etching or wet etching. However, it is preferable to carry out the etching using a highly anisotropic etching method (physical etching). By using a highly anisotropic etching method for etching, the processing accuracy of the pattern can be improved. It can be done. Furthermore, if the first etching is performed by dry etching, This can be done in the following process, but the first etching is performed by wet etching. In some cases, the first etching is performed using multiple steps. Therefore, the first etching involves: Dry etching is preferred.

[0016] Furthermore, the second etching process can be performed using either dry etching or wet etching. However, this can be done using etching methods where isotropic etching is dominant (chemical etching). Preferred. The second etching method is predominantly isotropic etching (chemical etching). By using (etching), the first conductive film can be side-etched. Therefore, For the second etching step, wet etching is preferable.

[0017] Here, the second etching is performed under conditions that involve side etching of the first conductive film. Therefore, the first conductive film recedes inward from the patterned thin film laminate. The side surface of the first conductive film after the second etching is more than the side surface of the patterned thin film laminate. It is also present on the inside. Furthermore, the patterned side of the first conductive film and the patterned The spacing between the thin film laminate and its sides will be approximately equal.

[0018] The first conductive film pattern refers to, for example, the gate electrode, gate wiring, and capacitive electrode. This refers to the top surface layout of the metal wiring being formed.

[0019] One aspect of the present invention involves forming a gate electrode layer using side etching, preferably in a recess. A resist mask having the above is used to provide a source electrode and a source electrode provided above the gate electrode layer. This is a method for fabricating an EL display device having a thin-film transistor with a drain electrode layer formed on it.

[0020] One aspect of the present invention relates to a first conductive film, a first insulating film, a semiconductor film, an impurity semiconductor film, and a second The conductive films are sequentially stacked to form a first resist mask, and the second conductive film is formed on top of the first resist mask. Using the first resist mask, the first insulating film, the semiconductor film, and the impurity semiconductor film are used. The body film and the second conductive film are subjected to a first etching to remove at least the surface of the first conductive film. The surface is exposed, and a second etching is performed on a portion of the first conductive film to remove the first insulating film. A gate electrode layer is formed such that its width is narrower than the width, and a second resist is placed on the second conductive film. A resist mask is formed, and the second conductive film and the impurity semiconductor are formed using the second resist mask. A third etching process is performed on the conductive film and a portion of the semiconductor film to form the source electrode and drain electrode. Thin-film transistors are formed by creating layers, source region and drain region layers, and semiconductor layers. Form the second resist mask and remove it, covering the thin film transistor to form the second insulating layer. The second insulating film is formed so as to expose a portion of the source electrode and drain electrode layers. An opening is formed in the film, and a first pixel electrode is selectively formed on the opening and the second insulating film. The process involves forming an EL layer on the first pixel electrode and forming a second pixel electrode on the EL layer. This is a method for manufacturing an EL display device characterized by [the following].

[0021] One aspect of the present invention relates to a first conductive film, a first insulating film, a semiconductor film, an impurity semiconductor film, and a second The conductive films are sequentially stacked to form a first resist mask, and the second conductive film is formed on the first resist mask. Using the first resist mask, the first insulating film, the semiconductor film, and the impurity semiconductor film are used. The body film and the second conductive film are subjected to a first etching to remove at least the surface of the first conductive film. The surface is exposed, and a second resist mask is formed on the second conductive film, and the second resist After forming the mask, a second etching is performed on a portion of the first conductive film to form the first insulating film. A gate electrode layer is formed so that its width is narrower than the width of the film, and the second resist mask is used Then, the second conductive film, the impurity semiconductor film, and a portion of the semiconductor film are subjected to a third etching process. Perform the following steps: source electrode and drain electrode layer, source region and drain region layer, and semiconductor layer A thin-film transistor is formed by forming the above, the second resist mask is removed, and the A second insulating film is formed by covering the thin-film transistor, and the source electrode and drain electrode layers are formed. An opening is formed in the second insulating film so as to expose a portion of it, and the opening and the second insulating film A first pixel electrode is selectively formed on the edge film, and an EL layer is formed on the first pixel electrode. This is a method for manufacturing an EL display device, characterized by forming a second pixel electrode on the EL layer. .

[0022] One aspect of the present invention relates to a first conductive film, a first insulating film, a semiconductor film, an impurity semiconductor film, and a second A first resist mass having a recess is formed by sequentially laminating conductive films. A layer is formed, and using the first resist mask, the first insulating film, the semiconductor film, and the front The impurity semiconductor film and the second conductive film are subjected to a first etching process, and the first conductive film At least the surface is exposed, and a second etching is performed on a portion of the first conductive film. A gate electrode layer is formed such that its width is narrower than the width of the insulating film 1, and the first resist By retracting the screen, the second conductive film superimposed on the recess of the first resist mask is A second resist mask is formed while exposing the material, and the second resist mask is used to form the A third etching is performed on the conductive film 2, the impurity semiconductor film, and a part of the semiconductor film. Forming a source electrode and drain electrode layer, a source region and a drain region layer, and a semiconductor layer. This forms a thin-film transistor, removes the second resist mask, and the thin-film transistor A second insulating film is formed by covering the zista, exposing a portion of the source electrode and drain electrode layers. An opening is formed in the second insulating film in such a manner, and the opening and the second insulating film are made Selectively form one pixel electrode, form an EL layer on the first pixel electrode, and on the EL layer This is a method for manufacturing an EL display device, characterized by forming a second pixel electrode on the surface.

[0023] One aspect of the present invention relates to a first conductive film, a first insulating film, a semiconductor film, an impurity semiconductor film, and a second A first resist mass having a recess is formed by sequentially laminating conductive films. A layer is formed, and using the first resist mask, the first insulating film, the semiconductor film, and the front The impurity semiconductor film and the second conductive film are subjected to a first etching process, and the first conductive film By exposing at least the surface and retracting the first resist mask, the first resist The second resist mask is subjected to the second resist mask while exposing the second conductive film that overlaps with the recess of the resist mask. After forming the second resist mask, a second etching is performed on a portion of the first conductive film. The gate electrode layer is formed by performing a process such that its width is narrower than the width of the first insulating film, Using the second resist mask, the second conductive film, the impurity semiconductor film and the semiconductor film A third etching is performed on a portion of the source electrode and drain electrode layer, source region and drain A thin-film transistor is formed by forming an in-region layer and a semiconductor layer, and the second resistor Remove the stock mask and cover the thin film transistor to form a second insulating film, and the source An opening is formed in the second insulating film so as to expose a portion of the electrode and drain electrode layers. The first pixel electrode is selectively formed on the opening and the second insulating film, and the first pixel electrode An EL (electroluminescent) layer is formed on top of the plate, and a second pixel electrode is formed on the EL layer, characterized by this process. This is a method for manufacturing a display device.

[0024] A method for manufacturing the above configuration, wherein the first resist mask has a recess, The first resist mask is preferably formed using a multi-gradation mask. By using this method, a resist mask with recesses can be formed in a simplified process.

[0025] By applying the above-described method for manufacturing an EL display device, the first etching process An element region is formed, and by the second etching, approximately equal to the side surface of the element region The side surface of the gate electrode layer can be formed inward by a certain distance.

[0026] A method for manufacturing an EL display device using the first etching and second etching of the above configuration. In either case, the first etching is performed by dry etching, and the second etching The etching is preferably performed by wet etching. It is preferable to perform this with high precision, and the second etching process involves side etching. It is necessary. Dry etching is preferred for high-precision machining, and wet etching is also preferable. Etching utilizes a chemical reaction, so it is less prone to side etching than dry etching. It's a stir-fry.

[0027] In the method for manufacturing the EL display device having the above configuration, the second insulating film is made by CVD or spalling. An insulating film formed by the tarting method and an insulating film formed by the spin coating method are stacked. It is preferable to form the silicon nitride film by CVD or sputtering. The first layer is formed by a spin coating method, and the second layer is formed by a spin coating method. By forming it in this way, impurity elements that may affect the electrical characteristics of the thin-film transistor may be affected. It protects thin-film transistors from damage and improves the flatness of the surface on which the pixel electrodes are formed, thereby increasing yield. This can prevent a decrease in [the value].

[0028] When applying the above-described method for manufacturing an EL display device, the thin-film transistor formed is a G The gate electrode layer has a gate insulating film covering it, and the gate insulating film has a semiconductor layer on it, and the semiconductor The body layer has a source region and a drain region, and the source region and drain region have a It has a drain electrode and a gate electrode, and a cavity is provided in contact with the side surface of the gate electrode layer. This is because the presence of a cavity lowers the dielectric constant (low- (Can be converted to k)

[0029] Furthermore, "membrane" refers to something that is not patterned and formed across the entire surface, and "layer" refers to This refers to a material that has been patterned into a desired shape using a resist mask or the like. However, layering Regarding the individual layers of a membrane, the terms "membrane" and "layer" are sometimes used interchangeably without any particular distinction.

[0030] Furthermore, "etching" refers to unintentional etching. In other words, etching is "etching." It is preferable to carry out the procedure under conditions that minimize the occurrence of [the specified problem].

[0031] In this specification, the term "having heat resistance" refers to any film that is heat-resistant in subsequent processes. Depending on the degree, the film maintains its shape as a film and retains the functions and characteristics required of the film. It means being able to do something.

[0032] "Gate wiring" refers to the wiring connected to the gate electrode of a thin-film transistor. Gate wiring is formed by the gate electrode layer. Gate wiring is also called a scan line. There is.

[0033] Furthermore, "source wiring" refers to the connection between the source electrode and the drain electrode of a thin-film transistor. This refers to the wiring that is connected. The source wiring is formed by the source electrode and drain electrode layers. Source wiring is sometimes also called signal wiring.

[0034] Furthermore, "power lines" refer to wiring connected to a power source and maintained at a constant potential. [Effects of the Invention]

[0035] It does not require a new photomask for gate electrode pattern formation, enabling the fabrication of thin-film transistors. The number of manufacturing steps can be significantly reduced, and the thin-film transistor can be applied to EL display devices. Therefore, the number of manufacturing steps for EL display devices can be significantly reduced.

[0036] More specifically, the number of photomasks can be reduced. Thin-film transistors can also be fabricated using a mask. Therefore, EL display equipment The number of manufacturing steps for the device can be significantly reduced.

[0037] Furthermore, unlike conventional technologies aimed at reducing the number of photomasks, back-side exposure and resin It does not require complex processes such as striflo and lift-off methods. Therefore, the yield is This allows for a significant reduction in the number of manufacturing steps for EL display devices without compromising performance.

[0038] Furthermore, conventional technologies aimed at reducing the number of photomasks sacrifice electrical characteristics. There were many unavoidable circumstances, but in one aspect of the present invention, the electrical This allows for a significant reduction in the number of manufacturing steps for thin-film transistors while maintaining their characteristics. Therefore, without sacrificing the display quality of the EL display device, the number of manufacturing steps for the EL display device can be increased. It can be reduced in width.

[0039] Furthermore, the above effects make it possible to significantly reduce the manufacturing cost of EL display devices. Furthermore, a thin-film transistor according to one aspect of the present invention has a cavity in contact with the end of the gate electrode layer. Therefore, the leakage current between the gate electrode and the drain electrode is small. [Brief explanation of the drawing]

[0040] [Figure 1] A diagram illustrating an example of a pixel circuit in a display device. [Figure 2] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 3] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 4] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 5] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 6] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 7] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 8] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 9]A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 10] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 11] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 12] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 13] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 14] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 15] A diagram illustrating an example of a method for fabricating thin-film transistors and display devices. [Figure 16] A diagram illustrating a multi-level mask. [Figure 17] A diagram illustrating the connection points of an active matrix substrate. [Figure 18] A diagram illustrating the connection points of an active matrix substrate. [Figure 19] A diagram illustrating the connection points of an active matrix substrate. [Figure 20] A diagram illustrating electronic devices. [Figure 21] A diagram illustrating electronic devices. [Figure 22] A diagram illustrating electronic devices. [Modes for carrying out the invention]

[0041] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention The present invention is not limited to the following description, and its form may not depart from the spirit and scope of the present invention. It will be readily apparent to those skilled in the art that the details can be modified in various ways. Therefore, The present invention is not limited to the embodiments described below. When describing the structure of an invention using planes, reference numerals that refer to the same thing are common across different drawings. They are used in this way. Also, when referring to similar items, the hatch pattern is the same, and no special designation is given. There may be cases where this is not the case. Also, the insulating film is not shown in the top view.

[0042] (Embodiment 1) In this embodiment, a method for fabricating a thin-film transistor and the thin-film transistor are matrix An example of a method for manufacturing an EL display device arranged in a specific pattern will be explained with reference to Figures 1 to 16. do.

[0043] EL display device that uses thin-film transistors as switching elements (active type EL display) Various types of pixel circuits are being considered for the display device. In this embodiment, a simple An example of a pixel circuit is shown in Figure 1, and a method for fabricating a pixel structure using this pixel circuit is described. This will be clarified. However, in this embodiment, the pixel circuit of the EL display device is not limited to the configuration shown in Figure 1. It is not something that can be determined.

[0044] In the pixel structure of the EL display device shown in Figure 1, pixel 21 is a first transistor 11, It has a second transistor 12, a third transistor 13, a capacitive element 14, and a light-emitting element 15. The first to third transistors are n-type transistors. First transistor 11 The gate electrode is connected to the gate wiring 16, and one of the source electrode and drain electrode (1 The electrodes are as follows: ) are connected to the source wiring 18, and the other of the source electrode and drain electrode ( This will be the second electrode. ) is the gate electrode of the second transistor 12 and one of the capacitive elements 14. It is connected to one electrode (referred to as the first electrode). The other electrode (the second electrode) of the capacitive element 14 (The electrode is one of the source electrode and drain electrode of the second transistor 12.) as the electrode of the third transistor 13) and one of the source electrode and the drain electrode of the third transistor 13 (the first electrode), and is connected to one of the electrodes of the light-emitting element 15 (the first electrode). The other of the source electrode and the drain electrode of the second transistor 12 (the second electrode) is connected to the second power supply line 19. The other of the source electrode and the drain electrode of the third transistor 13 (the second electrode) is connected to the first power supply line 17, and the gate electrode is connected to the gate wiring 16. The other electrode of the light-emitting element 15 (the second electrode) is connected to the common electrode 20. Here, the potentials of the first power supply line 17 and the second power supply line 19 are different.

[0045] The operation of the pixel 21 will be described. When the third transistor 13 is turned on by the signal of the gate wiring 16, the potentials of the first electrode of the second transistor 12, the first electrode of the light-emitting element 15, and the second electrode of the capacitor element 14 become equal to the potential (V , ) of the first power supply line 17. Here, since the potential (V ) of the first power supply line 17 is constant, the potential of the first electrode of the second transistor 12 17 and the like is constant (V ) 17 .

[0046] When the first transistor 11 is selected and turned on by the signal of the gate wiring 16, the potential (V ) of the signal from the source wiring 18 is input to the gate electrode of the second transistor 12 through the first transistor 11. 18 At this time, if the potential (V ) of the second power supply line 19 is higher than the potential (V 19 ) of the first power supply line 17, then V = V 17 - V gs = V 18 - V 17 and then V gs If it is greater than the threshold voltage of the second transistor 12, the second transistor Turn on ST12.

[0047] Therefore, when the second transistor 12 is operated in the linear region, the source wiring 18 Potential (V 18 By changing (for example, to a binary value), the ON state of the second transistor 12 and It is possible to control the ON / OFF state. In other words, by applying a voltage to the EL layer of the light-emitting element 15. It is possible to control whether or not it happens.

[0048] Furthermore, when the second transistor 12 is operated in the saturation region, the power of the source wiring 18 Place (V 18 By changing the value, the amount of current flowing through the light-emitting element 15 can be controlled. .

[0049] As described above, when the second transistor 12 is operated in the linear region, the light-emitting element 1 The voltage applied to 5 can be controlled, and the light-emitting state and non-light-emitting state of the light-emitting element 15 can be controlled. The state can be controlled. Such a driving method is, for example, digital time-gradation driving. It can be used for this purpose. Digital time-gradation driving divides one frame into multiple subframes. The drive method controls the light-emitting state and non-light-emitting state of the light-emitting element 15 in each subframe. This is the law. Also, when the second transistor 12 is operated in the saturation region, the light-emitting element 15 The amount of current flowing can be controlled, and the brightness of the light-emitting element 15 can be adjusted.

[0050] Next, the pixel structure to which the pixel circuit shown in Figure 1 is applied, and its fabrication method will be described below. ru.

[0051] Figures 2 to 6 show top views of thin-film transistors according to this embodiment, and Figure 6 is This is a completed diagram showing the pixel electrodes formed. Figures 7 to 9 show the A-A' shown in Figures 2 to 6. This is a cross-sectional view. Figures 10 to 12 are cross-sectional views of the line B-B' shown in Figures 2 to 6. Yes. Figures 13 to 15 are cross-sectional views taken along the line C-C' shown in Figures 2 to 6.

[0052] First, a first conductive film 102, a first insulating film 104, a semiconductor film 106, and an insulator are placed on the substrate 100. A pure semiconductor film 108 and a second conductive film 110 are formed. These films are formed as single layers. Alternatively, it may be a laminated film in which multiple films are stacked on top of each other.

[0053] The substrate 100 is an insulating substrate, and can be, for example, a glass substrate or a quartz substrate. In this embodiment, a glass substrate is used.

[0054] The first conductive film 102 is formed from a conductive material. The first conductive film 102 is, for example, Tan, molybdenum, chromium, tantalum, tungsten, aluminum, copper, neodymium, ni Conductive materials such as metallic materials like oats or scandium, or alloy materials mainly composed of these materials. It can be formed using a material. However, in a later step (such as the formation of the first insulating film 104) It needs to have sufficient heat resistance to withstand subsequent processes (such as etching the second conductive film 110). It is necessary to select a material that will not be etched or corroded. To this extent, the first conductive film 1 02 is not limited to specific materials.

[0055] The first conductive film 102 is produced by, for example, sputtering or CVD (thermal CVD or It can be formed by methods such as plasma CVD (including plasma CVD). However, it is not limited to specific methods. It is not something that should be done.

[0056] The first insulating film 104 is formed from an insulating material. The first insulating film 104 is, for example, It can be formed using silicon oxide films, nitride films, oxidogenic nitride films, or nitride oxide films, etc. However, like the first conductive film 102, it must be heat resistant and susceptible to etching or corrosion in subsequent processes. It is necessary to select a material that is not affected. In this respect, the first insulating film 104 is specific It is not limited to materials.

[0057] The first insulating film 104 is, for example, produced by a CVD method (thermal CVD method or plasma CVD method, etc.). It can be formed by methods including sputtering, but is not limited to specific methods. It's not that.

[0058] The first insulating film 104 functions as a gate insulating film.

[0059] The semiconductor film 106 is formed from a semiconductor material. For example, the semiconductor film 106 is made of silanga It can be formed using amorphous silicon or the like formed by the first derivative. Similar to the electrical film 102, heat resistance is required, and the material must not be etched or corroded in subsequent processes. A selection is required. In this respect, the semiconductor film 106 is not limited to a specific material. No, that's not the case. Therefore, germanium or similar materials can be used.

[0060] The semiconductor film 106 is produced by, for example, a CVD method (including thermal CVD or plasma CVD). ) or can be formed by sputtering or the like. However, it is not limited to a specific method. It is not something that can be done.

[0061] The semiconductor film 106 is preferably a multilayer film of a crystalline semiconductor film and an amorphous semiconductor film. Examples of crystalline semiconductor films include polycrystalline semiconductor films and microcrystalline semiconductor films.

[0062] A polycrystalline semiconductor film is a semiconductor film composed of crystal grains, with many grain boundaries between these crystal grains. This refers to a polycrystalline semiconductor film, which is formed, for example, by thermal crystallization or laser crystallization. In this case, the thermal crystallization method involves forming an amorphous semiconductor film on a substrate and then heating the substrate to create an amorphous film. This refers to a crystallization method for crystallizing amorphous semiconductors. Laser crystallization, on the other hand, refers to a method of crystallizing amorphous semiconductors on a substrate. A body film is formed, and the amorphous semiconductor film is irradiated with a laser to crystallize the amorphous semiconductor. This refers to the crystallization method. Alternatively, it refers to a crystallization method that involves adding crystallization-promoting elements such as nickel to induce crystallization. It is acceptable to do so. When crystallization is performed by adding a crystallization promoting element, a laser may be applied to the semiconductor film. Irradiation is preferable.

[0063] Polycrystalline semiconductors undergo LTP (Long-Term Crystallization), a process that crystallizes the glass substrate at a temperature and time that does not cause distortion. S (Low Temperature Poly Silicon) and crystallization at higher temperatures. For HTPS (High Temperature Poly Silicon) that undergoes modification To be classified.

[0064] A microcrystalline semiconductor film is a semiconductor film containing crystal grains with a particle size of approximately 2 nm to 100 nm. Yes, a film in which the entire surface is composed solely of crystal grains, or an amorphous semiconductor between the crystal grains. This includes intervening elements. As a method for forming a microcrystalline semiconductor film, crystal nuclei are formed and the crystal nuclei are A method for growing an amorphous semiconductor film, and in contact with the amorphous semiconductor film, an insulating film and a metal film. A layer is formed, and by irradiating the metal film with a laser, the heat generated in the metal film causes amorphous material to form. Methods for crystallizing semiconductors can be used. However, thermal crystallization of amorphous semiconductor films is not possible. Crystalline semiconductor films formed using methods or laser crystallization are not included.

[0065] As the semiconductor film 106, for example, an amorphous semiconductor film is formed by stacking an amorphous semiconductor film on a crystalline semiconductor film. Using a multilayer film allows the transistors in the pixel circuit of an EL display device to operate at high speed. This is possible. Here, the crystalline semiconductor film is a polycrystalline semiconductor (LTPS and HTPS A film containing (or) may be applied, or a microcrystalline semiconductor film may be applied.

[0066] Furthermore, by having an amorphous semiconductor film on top of a crystalline semiconductor film, the surface of the crystalline semiconductor film becomes acidic. This prevents the device from being corrupted. It also improves voltage resistance and reduces off-current. It is possible.

[0067] However, as long as the pixel circuit of the EL display device is operating normally, the bonding of the semiconductor film 106 The crystallinity is not particularly limited.

[0068] The impurity semiconductor film 108 is a semiconductor film containing an impurity element that imparts conductivity. It is formed by semiconductor material gases, etc., to which impurity elements that impart electrical properties are added. In this configuration, an n-type thin-film transistor is provided, for example, phosphine (chemical formula: PH3) This can be provided by a silicon film containing phosphorus, formed by a silane gas containing [the substance]. Similar to the first conductive film 102, it must be heat resistant and not etched or corroded in subsequent processes. It is necessary to select a suitable material. In this respect, the impurity semiconductor film 108 is a specific material. This is not limited to the material. Furthermore, the crystallinity of the impurity semiconductor film 108 is not particularly limited. It is not done. Also, a portion of the semiconductor layer formed by the semiconductor film 106 is doped. When an ohmic contact area is provided by means of a ring or the like, the impurity semiconductor film 108 There is no need to provide it.

[0069] In this embodiment, in order to fabricate an n-type thin-film transistor, a conductive additive is provided. Arsenic may be used as the impurity element, and the s Langas should contain arsine (chemical formula: AsH3) at the desired concentration.

[0070] The formation of the impurity semiconductor film 108 is, for example, by CVD (thermal CVD or plasma CVD). This can be done by methods such as Method D, etc. However, it is not limited to a specific method. stomach.

[0071] The second conductive film 110 is a conductive material (such as the material listed as the first conductive film 102). This is formed from a different material than the first conductive film 102. Here, "different material" means This refers to materials with different main components. Specifically, etching is performed by the second etching process, which will be explained later. A material that is less prone to rubbing should be selected. Also, similar to the first conductive film 102, heat resistance It is necessary to select a material that will not be chipped or corroded in subsequent processes. Therefore, To the extent that, the second conductive film 110 is not limited to a specific material.

[0072] The second conductive film 110 may be produced by, for example, sputtering or CVD (thermal CVD or It can be formed by methods such as plasma CVD (including plasma CVD). However, it is not limited to specific methods. It is not something that should be done.

[0073] Furthermore, the first conductive film 102, the first insulating film 104, the semiconductor film 106, and impurities described above are also included. The heat resistance required for the first conductive film 108 and the second conductive film 110 is 02 has the highest conductivity, followed by the second conductive film 110 in the order described above, with the second conductive film 110 having the lowest conductivity. For example, semiconductor If the body membrane 106 is an amorphous semiconductor film containing hydrogen, then by raising the temperature to approximately 300°C or higher, half Hydrogen is desorbed from the conductive film, and its electrical properties change. Therefore, for example, the semiconductor film 106 is formed In the subsequent steps, it is preferable to maintain a temperature that does not exceed 300°C.

[0074] Next, the first resist mask 112 is formed on the second conductive film 110 (Figure 7(A)). See Figures 10(A) and 13(A). Here, the first resist mask 112 is a recess or It is preferable that the resist mask has convex portions. In other words, multiple regions of different thicknesses It can also be called a resist mask consisting of regions (in this case, two regions). The first resist In the mask 112, the thicker regions are called the convex parts of the first resist mask 112, and the thinner regions The region will be referred to as the recess of the first resist mask 112. However, it is not limited to this. A resist mask without recesses or protrusions may also be used.

[0075] In the first resist mask 112, the regions where the source electrode and drain electrode layers are formed A convex portion is formed in the region, and the semiconductor layer is exposed without having source electrode and drain electrode layers. A recess is formed in the area being treated.

[0076] The first resist mask 112 can be formed by using a multi-gradation mask. Here, we will explain multi-level masks with reference to Figure 16.

[0077] A multi-gradation mask is a mask that allows exposure at multiple levels of light intensity, and typically, This refers to a system that performs exposure using three levels of light intensity: an exposed area, a partially exposed area, and an unexposed area. By using a mask, multiple (typically two types) can be created in a single exposure and development process. A resist mask with thickness can be formed. Therefore, a multi-level mask is used. This allows for a reduction in the number of photomasks required.

[0078] Figures 16(A-1) and 16(B-1) show cross-sectional views of typical multi-level masks. Figure 16(A-1) shows the gray tone mask 140, and Figure 16(B-1) shows the half tone mask. This shows mask 145.

[0079] The gray tone mask 140 shown in Figure 16(A-1) is placed on a light-transmitting substrate 141. A light-shielding portion 142 formed by a light-shielding film, and a diffraction grating provided by the pattern of the light-shielding film. It consists of 143 parts.

[0080] The diffraction grating section 143 has slits spaced at intervals less than or equal to the resolution limit of the light used for exposure. The amount of light transmitted is controlled by having dots or a mesh, etc. Note: Diffraction grating section 143 The slits, dots, or mesh provided may be periodic or aperiodic. It can be anything.

[0081] As the light-transmitting substrate 141, quartz or the like can be used. Light-shielding portion 142 and The light-shielding film constituting the diffraction grating portion 143 may be formed using a metal film, preferably a chrome film. It is provided by chromium or chromium oxide, etc.

[0082] When light is shone onto the gray tone mask 140 for exposure, as shown in Figure 16(A-2). As such, the light transmittance in the region superimposed on the light-shielding portion 142 becomes 0%, and the light-shielding portion 142 or In the region where the diffraction grating 143 is not provided, the light transmittance is 100%. The light transmittance in the lattice portion 143 is generally in the range of 10-70%, and the slit of the diffraction grating, It can be adjusted by changing the spacing of dots or meshes, etc.

[0083] The halftone mask 145 shown in Figure 16(B-1) is placed on a light-transmitting substrate 146. A semi-transparent portion 147 formed by a semi-transparent film, and a light-shielding portion 148 formed by a light-shielding film. It is composed of.

[0084] The semi-transparent portion 147 is made of MoSiN, MoSi, MoSiO, MoSiON, CrSi, etc. It can be formed using a film. The light-shielding portion 148 is similar to the light-shielding film of the gray tone mask. It may be formed using a metal film, preferably provided by chromium or chromium oxide, etc. .

[0085] When light is shone onto the halftone mask 145 for exposure, as shown in Figure 16(B-2) As such, the light transmittance in the region superimposed on the light-shielding portion 148 becomes 0%, and the light-shielding portion 148 or In the region where the semi-transparent portion 147 is not provided, the light transmittance is 100%. The light transmittance in section 147 is generally in the range of 10-70%, depending on the type or shape of the material being formed. The film thickness and other properties can be adjusted.

[0086] By exposing and developing using a multi-gradation mask, a first layer having regions with different film thicknesses is created. A dystomask 112 can be formed.

[0087] However, this is not limited to the above, and the first resist mask can be formed without using a multi-gradation mask. It may be done. Also, as described above, the first resist mask does not have recesses or protrusions. A resist mask may also be used.

[0088] Next, the first etching is performed using the first resist mask 112. The insulating film 104, semiconductor film 106, impurity semiconductor film 108 and second conductive film 110 are ester The thin film laminate 114 is formed by patterning using ching (Figures 2, 7(B), and 10). (B), see Figure 13(B). At this time, at least the surface of the first conductive film 102 is exposed. It is preferable to do so. This etching process is called the first etching. The etching can be done using dry etching or wet etching. When the etching is performed by dry etching, it can be done in one step, but the first When etching is performed by wet etching, the first etching is performed in multiple steps. It is recommended to do this. The etching rate differs depending on the type of film to be etched, and in one step Because it is difficult to do.

[0089] The first etching can be performed, for example, by a three-stage dry etching. First, Cl Etching was performed in a mixed gas of 2 gas, CF4 gas, and O2 gas, and then in Cl2 gas only. Etching should be performed using [method name], and finally, etching should be performed using only CHF3 gas. .

[0090] Next, a second etching is performed using the first resist mask 112. That is, the first The conductive film 102 is patterned by etching to form the gate electrode layer 116 (Figure 3. See Figures 7(C), 10(C), and 13(C). This etching process is the second etching process. It's called "watching."

[0091] The gate electrode layer 116 is the gate electrode, gate wiring, and capacitive element of the thin-film transistor. It constitutes one of the electrodes and the support portion. When referred to as gate electrode layer 116A, Gate wiring, gate electrode of the first transistor 11, and gate of the third transistor 13 This refers to the electrode layer that constitutes the electrode. When referred to as gate electrode layer 116B, it refers to the second electrode. This refers to the electrode layer that constitutes the gate electrode of the inverter 12 and one of the electrodes of the capacitive element 14. When referred to as electrode layer 116C, it refers to the electrode layer that constitutes the support part. These are collectively referred to as the gate electrode layer 116.

[0092] The second etching is performed on the side surface of the gate electrode layer 116 formed by the first conductive film 102. However, this is carried out by etching conditions that form on the inside of the side surface of the thin film laminate 114. In other words... The side surface of the gate electrode layer 116 is formed in contact with the bottom surface of the thin film laminate 114. Perform a check (in the A-A' section, the width of the gate electrode layer 116 is equal to the width of the thin film laminate 114) (Etching is performed to make it smaller). Furthermore, etching of the second conductive film 110. Under conditions where the etching rate is small and the etching rate for the first conductive film 102 is large This is done by etching the first conductive film 102 against the second conductive film 110. This is done under conditions where the selectivity ratio is large. By performing the second etching under these conditions, A electrode layer 116 can be formed.

[0093] The shape of the side surface of the gate electrode layer 116 is not particularly limited. For example, it may be tapered. It is also acceptable. The shape of the side surface of the gate electrode layer 116 is determined by the chemical used in the second etching process. It is determined by conditions such as these.

[0094] Here, the etching rate for the second conductive film 110 is small, and the first conductive film Conditions for a high etching rate for 102, or conditions for the second conductive film 110 The condition for a high etching selectivity of conductive film 102 is the following first requirement and second This refers to something that meets the requirements.

[0095] The first requirement is that the gate electrode layer 116 remains where it is needed. The necessary areas for 116 are the regions shown by dotted lines in Figures 3 to 6. That is, the second After etching, the gate electrode layer 116 is the gate wiring, the gate electrode of the transistor, And it is necessary that it remain to constitute one electrode of the capacitive element. Token For the layers to form gate wiring, a second etching is performed to prevent these wires from breaking. It is necessary to do the following: As shown in Figures 3 and 7, from the side of the thin film laminate 114, at a distance d Preferably, the side surface of the gate electrode layer 116 is formed by a distance of 1 inward, and the spacing d1 is determined by the implementer. You can set it appropriately according to the layout.

[0096] The second requirement is the minimum width d3 of the gate wiring formed by the gate electrode layer 116, and The source wiring and power lines, which are composed of the source electrode and drain electrode layers 120, have a minimum width d The goal is for 2 to be appropriate (see Figure 6). The second etching process removes the source electrode and When the drain electrode layer 120 is etched, the minimum width d2 of the source wiring and power lines becomes smaller. This is because the current density of the source wiring and power lines becomes excessive, resulting in a decrease in electrical characteristics. Therefore, the second etching process does not result in an excessive etching rate of the first conductive film 102. Furthermore, the process is carried out under conditions where the etching rate of the second conductive film 110 is as small as possible.

[0097] Furthermore, it is difficult to increase the minimum width d2 of source wiring and power lines. The minimum width d2 of the power line is determined by the minimum width d4 of the semiconductor layer superimposed on the source wiring and power line. In order to increase the minimum width d2 of the source wiring and power lines, the minimum width d4 of the semiconductor layer must be increased. This is because it would require increasing the size of the gate wiring, making it difficult to insulate it from adjacent gate wiring. The minimum width d4 of the semiconductor layer should be less than approximately twice the aforementioned spacing d1. In other words, The spacing d1 is made larger than approximately half of the minimum width d4 of the semiconductor layer.

[0098] Furthermore, the portion where the semiconductor layer overlapping the source wiring and power lines has a minimum width d4 is... The electrode layer can be appropriately provided at the necessary locations to separate each element. Therefore, the gate electrode layer 116 does not remain in the area where the semiconductor layer width d4 overlaps. It is possible to form a pattern.

[0099] Furthermore, the portion formed by the source electrode and drain electrode layers and connected to the pixel electrode layer The width of the electrodes is preferably the minimum width d2 of the source wiring and power lines.

[0100] As explained above, the second etching is performed under conditions that involve side etching. This is extremely important. The second etching involves side etching of the first conductive film 102. As a result, not only between adjacent gate wirings, which are formed by the gate electrode layer 116, but also Patterns can be formed to arrange the elements within the pixel circuit in a desired manner. That is the reason.

[0101] Here, side etching refers to the thickness direction of the etched film (the direction perpendicular to the substrate surface or (Not only in the direction perpendicular to the surface of the underlying film of the film to be etched, but also in the direction perpendicular to the thickness direction.) The etched film (in a direction parallel to the substrate surface or parallel to the surface of the underlying film of the etched film) This refers to etching where a layer is removed. The edges of the etched film that have been side-etched are... Depending on the etching rate of the etching gas or chemical used for etching the etching film They are formed into various shapes, but often the ends are formed to be curved. .

[0102] Furthermore, the gate electrode layer 116C shown in Figure 3 serves as a support for the thin film laminate 114. It is possible. By having a support portion, it prevents the peeling of films such as gate insulating films formed above the gate electrode layer. This prevents chipping. Furthermore, by providing a support part, chipping can be prevented by the second etching. This prevents the cavity area formed in contact with the electrode layer 116 from becoming unnecessarily large. Furthermore, by providing the support portion, the thin film laminate 114 will not be destroyed or damaged by its own weight. This can also prevent this from happening, and is preferable because it improves yield. However, the support part It is not limited to the form it has, and it does not require a support structure.

[0103] As explained above, the second etching is preferably performed by wet etching. It's nice.

[0104] When the second etching is performed by wet etching, the first conductive film 102 is as Aluminum or molybdenum is formed, and titanium or tungsten is used as the second conductive film 110. To form the ion, a chemical solution containing nitric acid, acetic acid, and phosphoric acid can be used for etching. Alternatively, Molybdenum is formed as the first conductive film 102, and titanium and aluminum are formed as the second conductive film 110. If you form a tungsten or aluminum alloy and use a chemical solution containing hydrogen peroxide for etching, good.

[0105] When the second etching is performed by wet etching, most preferably the first guide A laminated film is formed by forming molybdenum on neodymium-doped aluminum as the electrode film 102. Then, tungsten is formed as the second conductive film 110, and 2% nitric acid and vinegar are used for etching. A chemical solution containing 10% acid and 72% phosphoric acid is used. By using a chemical solution with this composition, The first conductive film 102 is etched without the second conductive film 110 being etched. Furthermore, the neodymium added to the first conductive film 102 contributes to reducing the resistance of aluminum and to the hygroscopic effect. It was added for the purpose of preventing spoilage.

[0106] Furthermore, the gate electrode layer 116, as viewed from above, is formed to have corners (see Figure 3). This is because the second etching process that forms the gate electrode layer 116 proceeds in a generally isotropic manner. Therefore, the distance d1 between the side surface of the gate electrode layer 116 and the side surface of the thin film laminate 114 becomes approximately equal. This is because it is etched in that manner.

[0107] Next, the first resist mask 112 is moved back to expose the second conductive film 110. , a second resist mask 118 is formed. The first resist mask 112 is retracted, As a means of forming the second resist mask 118, for example, an oxygen plasma is used. A single example is mentioned. However, the first resist mask 112 is moved back and the second resist The means of forming the mask 118 are not limited to this. Second resist mask 1 The region where 18 is formed roughly coincides with the region of the convex portion of the first resist mask 112. Oh, here we'll discuss the case where the second resist mask 118 is formed after the second etching. As explained above, the process is not limited to this, and after forming the second resist mask 118, the second E You may perform a check.

[0108] Furthermore, if a multi-level mask is not used to form the first resist mask 112, a different A second resist mask 118 can be formed separately using a photomask.

[0109] Next, using the second resist mask 118, the second conductive film in the thin film laminate 114 110 is etched to form the source electrode and drain electrode layer 120 (Figures 4, 8) See Figures D, 11(D), and 14(D). Here, the etching conditions are as follows: Second conductive film 1 Select conditions in which erosion and corrosion do not occur or are unlikely to occur on films other than those specified in 10. In particular, It is important to carry out the process under conditions that prevent or minimize erosion and corrosion of the electrode layer 116. .

[0110] Furthermore, the source electrode and drain electrode layer 120 are the source electrode of the thin-film transistor or This includes the drain electrode, source wiring, power line, the other electrode of the capacitive element, and the thin-film transistor. An electrode is formed to connect one of the electrodes of the light-emitting element. Source electrode and drain electrode layer 1 When referred to as 20A, this refers to the source wiring 18 and the source electrode of the first transistor 11. This refers to the electrode layer that constitutes one of the source electrode and drain electrode. Source electrode and drain electrode layer 120 When referred to as B, it refers to the electrode layer constituting the first power line 17. Source electrode and drain When referred to as the in electrode layer 120C, the source electrode and drain of the first transistor 11 are used. The other side of the in electrode, and the electrode constituting the connection between the first transistor 11 and the pixel electrode. This refers to the polar layer. When the source electrode and drain electrode layer 120D is used, it refers to the second power line. 19, and one of the electrodes constituting the source electrode and drain electrode of the second transistor 12. This refers to the layer. When referring to the source electrode and drain electrode layer 120E, it refers to the third transient This refers to the electrode layer that constitutes one of the source electrode and drain electrode of STA 13. When referred to as the drain electrode layer 120F, the other electrode of the capacitive element 14, the second transistor The source electrode and drain electrode of the zista 12, and the other side of the source electrode of the third transistor 13. and the other drain electrode, and the electrode connected from these to one electrode of the light-emitting element constitute the same electrode. This refers to the electrode layer.

[0111] Furthermore, the second resist mask 118A overlaps with the source electrode and drain electrode layer 120A. The second resist mask 118B refers to the source electrode and drain electrode layer 1 This refers to the one superimposed on 20B, and the second resist mask 118C is the source electrode and the drain This refers to the layer superimposed on the electrode layer 120C, and the second resist mask 118D is the source electrode. And refers to the layer superimposed on the drain electrode layer 120D, and the second resist mask 118E is, This refers to the layer superimposed on the source electrode and drain electrode layer 120E, and the second resist mask 1 18F refers to the layer superimposed on the source electrode and drain electrode layer 120F.

[0112] Furthermore, the etching of the second conductive film 110 in the thin film laminate 114 is performed by wet etching. Either etching or dry etching may be used.

[0113] Next, the upper part of the impurity semiconductor film 108 and semiconductor film 106 in the thin film stack 114 ( The back channel portion is etched to form the source region and drain region 122, and the semiconductor layer 1 Forms 24 (see Figures 5, 8(E), 11(E), and 14(E)). Here The chipping conditions involve etching and corrosion of films other than the impurity semiconductor film 108 and semiconductor film 106. Select conditions under which the following do not occur or are unlikely to occur. In particular, conditions under which erosion and corrosion of the gate electrode layer 116 occur. It is important to carry out the procedure under conditions that do not cause or are unlikely to cause the problem.

[0114] Furthermore, the upper part of the impurity semiconductor film 108 and semiconductor film 106 in the thin film laminate 114 ( Etching of the back channel area is performed by dry etching or wet etching. It is possible.

[0115] Subsequently, the second resist mask 118 is removed, and the thin-film transistor is completed (Figure 6). See Figures 8(F), 11(F), and 14(F). As explained above, thin film transient A stanza can be created using a single photomask (multi-tone mask).

[0116] Furthermore, the process described above with reference to Figures 8(F) and 8(E) is collectively referred to as the third E. It is called etching. The third etching can be done in multiple stages, as explained above. That's fine, or you can do it all at once.

[0117] A second insulating film is formed by covering the thin-film transistor formed in the manner described above. , the second insulating film may be formed only by the first protective film 126, but here it is formed by the first protective film 126 and the second protective film 128 (see FIGS. 9(G), 12(G), 15(G) . The first protective film 126 may be formed in the same manner as the first insulating film 104, but preferably is formed of silicon nitride containing hydrogen or silicon oxynitride containing hydrogen, to prevent impurities such as metal from entering and diffusing into the semiconductor layer and being contaminated.

[0118] The second protective film 128 is formed by a method that makes the surface substantially flat. By making the surface of the second protective film 128 substantially flat, it is possible to prevent breakage or the like of the first pixel electrode layer 132 formed on the second protective film 128. Therefore, here, "substantially flat" means that it is sufficient as long as it can achieve the above object, and high flatness is not required .

[0119] Note that the second protective film 128 can be formed by, for example, spin coating with a photosensitive polyimide, acrylic, or epoxy resin or the like. However, it is not limited to these materials or forming methods.

[0120] Note that the second protective film 128 is formed by laminating the above protective film formed by a method that makes the surface substantially flat and a protective film that covers this to prevent the intrusion and release of moisture. It is preferable that the protective film for preventing the intrusion and release of moisture is specifically formed of silicon nitride, silicon oxynitride, aluminum oxynitride, or aluminum nitride. As the forming method, it is preferable to use a sputtering method.

[0121] Next, the first opening 130 and the second opening 131 are formed in the second insulating film (Figure 9( See Figures H, 12(H), and 15(H). The first opening 130 is for the source electrode and It is formed so as to reach at least the surface of the rain electrode layer. The second opening 131 is a gate Formed to reach at least the surface of the electrode layer. First opening 130 and second opening The method for forming 131 is not limited to a specific method, and can be applied depending on the diameter of the first opening 130, etc. The applicator can choose as appropriate. For example, dry etching can be performed using photolithography. This allows the first opening 130 and the second opening 131 to be formed.

[0122] The first opening 130 is provided so as to reach the source electrode and drain electrode layer 120. As shown in Figure 6, multiple openings are provided where necessary. The first opening 130A is The source electrode and drain electrode layer 120C are provided, and the first opening 130B is provided on the source electrode and The drain electrode layer 120B is provided, and the first opening 130C is the source electrode and the drain electrode. The first opening 130D is located on layer 120E, and the source electrode and drain electrode layer 120F is located on layer 120F. It will be set up there.

[0123] The second opening 131 is provided so as to reach the gate electrode layer 116. In other words, the second opening 131 is not only the second insulating film, but also the first insulating film 104 and the semiconductor layer. 124 is also provided by removing the desired locations.

[0124] Furthermore, by forming the opening using photolithography, one photomask can be used. It will be used.

[0125] Next, the first pixel electrode layer 132 is formed on the second insulating film (Figures 6, 9(H), and 1). See Figure 15(H) (2(H)). The first pixel electrode layer 132 is the first aperture 130 or The source electrode and drain electrode layer 120 or gate electrode layer 11 are separated by the second opening 131. It is formed to connect to 6. Specifically, the first pixel electrode layer 132 is formed to connect to the first aperture The source electrode and drain electrode layer 120C are connected via 130A, and the first opening 13 The source electrode and drain electrode layer 120B are connected via 0B, and the first opening 130C It is connected to the source electrode and drain electrode layer 120E via the first opening 130D It is connected to the source electrode and drain electrode layer 120F, and through the second opening 131 It is formed to be connected to the first pixel electrode layer 116B. It can be formed as a single layer, or as a laminated film by stacking multiple films.

[0126] Furthermore, by forming the first pixel electrode layer 132 using photolithography, You will need to use one mask.

[0127] Since the thin-film transistors in the pixels are n-type transistors, the first pixel electrode layer 1 32 is preferably formed from a material that will serve as the cathode. The material that will serve as the cathode has a work function Examples of materials with small molecular weights include Ca, Al, MgAg, AlLi, etc.

[0128] Next, a partition wall 133 is formed on the side surface (end) of the first pixel electrode layer 132 and on the second insulating film. The partition wall 133 has an opening, and the first pixel electrode layer 132 is exposed at the opening. The partition wall 133 is formed using an organic resin film, an inorganic insulating film, or an organic polysiloxane. It is formed by [specific method]. Specifically, it may be formed using polyimide, polyamide, polyimide amide, acrylic, or benzocyclobutene-based resin. In particular, using a photosensitive material, an opening is formed on the first pixel electrode layer 132, and it is preferable that the side wall of the opening is formed as an inclined surface having a continuous curvature. Next, the EL layer 134 is formed so as to contact the first pixel electrode layer 132 at the opening of the partition wall 133. The EL layer 134 may be composed of a single layer or a laminated film formed by laminating a plurality of layers. The EL layer 134 has at least a light-emitting layer. The light-emitting layer is preferably connected to the second pixel electrode layer 135 via a hole transport layer. Then, the second pixel electrode layer 135 is formed of a material that becomes an anode so as to cover the EL layer 134. The second pixel electrode layer 135 corresponds to the common electrode 20 in FIG. 1. The second pixel electrode layer 135 can be formed of a conductive material having translucency. Here, examples of the conductive material having translucency include indium tin oxide (hereinafter referred to as ITO), indium oxide containing tantalum oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, or indium tin oxide added with silicon oxide. The formation of the film of the conductive material having translucency may be performed by a sputtering method, a CVD method, or the like, but is not limited to a specific method. Also, the second pixel electrode layer 135 may be formed as a single layer or as a laminated film in which a plurality of films are laminated.

[0129]

[0130] <​​​​​​​​​​​​​​​​​ Here, ITO is used as the second pixel electrode layer 135. Therefore, the first pixel electrode layer 132, the EL layer 134, and the second pixel electrode layer 135 overlap. Then, the light-emitting element 136 is formed. The light-emitting element 136 corresponds to the light-emitting element 15 in Figure 1. After this, to prevent oxygen, hydrogen, moisture, carbon dioxide, etc. from entering the light-emitting element 136, It is preferable to form a third protective film 137 on the second pixel electrode layer 135 and the partition wall 133. (Not shown in the diagram). The third protective film 137, like the second protective film 128, is made of a material that protects against moisture. Select materials that have the function of preventing the intrusion and release of these substances. Examples include silicon nitride and silicon oxide nitride. Preferably, it is formed of aluminum oxide nitride or aluminum nitride, etc. Furthermore, it is preferable to have a silicon nitride film or a DLC film, etc., covering the third protective film.

[0132] Then, to prevent exposure to the outside air, a protective film (laminated film, UV-cured resin) is applied. Further packaging (enclosure) with a film or cover material is preferred. The protective film and cover material are made of a material with low gas permeability and minimal degassing. It is preferable to do so.

[0133] As explained above, the light-emitting element of a top-emission type EL display device It can be formed up to this point (see Figures 9(I), 12(I), and 15(I)). However, The EL display device of this embodiment is not limited to the above description, and may have a bottom emission structure (bottom emission EL display device of the dual emission type, or double-sided injection structure (dual emission) type EL display device It can also be applied to the placement. In the bottom-face injection structure and double-sided injection structure, the first pixel electrode layer A transparent conductive material can be used for 132. Furthermore, the first pixel electrode layer 132 is made bright. When formed from a material that forms the electrode, the first pixel electrode layer 132 is, for example, made of ITO. It can be formed in this way. By making the first pixel electrode layer 132 such a structure, light emission This improves the efficiency of extraction and enables the fabrication of bottom-emission type EL display devices. This is possible. Then, a second pixel is formed by a cathode material so as to cover the EL layer 134. It is preferable to form an electrode layer 135. The second pixel electrode layer 135 is located on the common electrode 20 in Figure 1. It corresponds to this. The material that will become the cathode should be a material with a small work function, such as Ca, Al, MgAg. Examples include AlLi, etc. Note that the EL layer 134 and the second pixel electrode layer 135 are masks. It is preferable to form it by deposition via [a certain method]. Therefore, the second pixel electrode layer 135 is formed by deposition It is preferable to form the pixels of the EL display device using a material that can be formed by [method / formation]. When configured with the circuit shown in 1, the first pixel electrode layer 132 is the anode, and the second pixel It is preferable to use the electrode layer 135 as the cathode.

[0134] Furthermore, the protective film described above is not limited to the materials or formation methods described above, and the EL layer Any film that does not obstruct light and can prevent deterioration would suffice.

[0135] Alternatively, in the upper surface ejection structure, the first includes the region in which the pixel circuit is formed. A pixel electrode layer 132A may be formed. In this case, first, the first pixel electrode layer 132B is formed. And only a conductive layer corresponding to the first pixel electrode layer 132C is formed, and the first aperture is formed on the conductive layer An insulating film having portion 130D is formed, and the source electrode and drain are connected through the first opening 130D. The first pixel electrode layer 132A should be formed so as to be connected to the in electrode layer 120F. By forming the first pixel electrode layer 132A so as to include the region where the elementary circuit is formed, This allows for an expanded light-emitting area, enabling higher-resolution displays.

[0136] Here, we have discussed organic EL elements as light-emitting elements, but inorganic elements can also be used as light-emitting elements. It is also possible to use electroluminescent (EL) elements.

[0137] Here, the terminal connection portion of the active matrix substrate fabricated by the above process is shown in Figure This will be explained with reference to Figures 17 through 19.

[0138] Figures 17 to 19 show the active matrix substrate fabricated by the above process. The top view and cross-sectional view of the terminal connection section on the gate wiring side and the terminal connection section on the source wiring side are shown.

[0139] Figure 17 shows the pixel section at the terminal connection on the gate wiring side and the terminal connection on the source wiring side. The top view shows the gate wiring and source wiring extending from there. Note that the first power line 17 and The power lines 19 of 2 may be the same as the source wiring 18. Also, the partition wall 133 and The pixel electrode layer 135 of the second pixel is not shown in Figure 17.

[0140] Figure 18 shows a cross-sectional view of X-X' in Figure 17. That is, Figure 18 shows gate wiring. A cross-sectional view of the terminal connection portion on the side is shown. In Figure 18, only the gate electrode layer 116 is exposed. The terminal portion is connected to the region where this gate electrode layer 116 is exposed.

[0141] Figure 19 shows an example of a cross-sectional view at Y-Y' in Figure 17. That is, Figure 19 is the source An example of a cross-sectional view of the terminal connection on the wiring side is shown. At Y-Y' in Figure 19, the gate electrode Layer 116 and the source electrode and drain electrode layer 120 are the first pixel electrode layer 132 (at least (Also connected via the same layer as the first pixel electrode layer 132B or the first pixel electrode layer 132C) Figure 19 shows the gate electrode layer 116 and the source electrode and drain electrode layers 120. Various connection configurations are shown. Here, the terminal connection part of the EL display device can be any of these. You may use this, or you may use a connection configuration other than that shown in Figure 19. Source electrode and By connecting the rain electrode layer 120 to the gate electrode layer 116, the height of the terminal connection portion is approximately It can be made equal.

[0142] The number of openings is not particularly limited to the number of openings shown in Figure 19. Not only may an opening be provided, but multiple openings may also be provided for a single terminal. By providing multiple openings, the etching process for forming the openings is insufficient. Even if the opening is not properly formed for reasons such as those mentioned above, electrical connections can be made through other openings. It can be revealed. Furthermore, even if all openings are formed without problems, contact This is preferable because it allows for a larger surface area, thereby reducing contact resistance.

[0143] In Figure 19(A), the edges of the first protective film 126 and the second protective film 128 are etched, etc. This removes the gate electrode layer 116 and the source electrode and drain electrode layers 120, exposing them. And in this exposed region, the first pixel electrode layer 132 (at least the first pixel electrode layer 1 Electrical connection is achieved by forming 32B (or the same layer as the first pixel electrode layer 132C). The top view shown in Figure 17 corresponds to the top view in Figure 19(A).

[0144] Furthermore, the area where the gate electrode layer 116 and the source electrode and drain electrode layers 120 are exposed The formation of the region can be carried out simultaneously with the formation of the first opening 130 and the second opening 131. ru.

[0145] In Figure 19(B), the first protective film 126 and the second protective film 128 have a third opening 160. A is provided, and the edges of the first protective film 126 and the second protective film 128 are etched or otherwise By being removed, the gate electrode layer 116 and the source electrode and drain electrode layers 120 are exposed. The first pixel electrode layer 132 (at least the first pixel electrode layer) is placed in this exposed region. By forming 132B (or the same layer as the first pixel electrode layer 132C), electrical connections are realized. It is showing.

[0146] Furthermore, the formation of the third opening 160A and the formation of the region in which the gate electrode layer 116 is exposed. This can be done simultaneously with the formation of the first opening 130 and the second opening 131.

[0147] In Figure 19(C), the first protective film 126 and the second protective film 128 have a third opening 160. The openings B and the fourth 161 are provided, so that the gate electrode layer 116 and the source electrode and The drain electrode layer 120 is exposed, and the first pixel electrode layer 132 (minor) is placed in this exposed region. Even if not present, the same layer as the first pixel electrode layer 132B or the first pixel electrode layer 132C is formed. This is how the electrical connection is achieved. Here, similar to Figures 19(A) and (B), The edges of protective film 1 126 and protective film 2 128 have been removed by etching or the like. This area is used as a terminal connection point.

[0148] Furthermore, the formation of the third opening 160B and the fourth opening 161, and the gate electrode layer 11 The formation of the region where 6 is exposed occurs simultaneously with the formation of the first opening 130 and the second opening 131. It can be done.

[0149] Furthermore, the third opening 160 is used for the source electrode and drain electrode, similar to the first opening 130. The fourth opening 161 is provided to reach the polar layer 120, and is similar to the second opening 131. It is provided so as to reach the gate electrode layer 116. And, in Figures 18 and 19, The wall 133 and the second pixel electrode layer 135 are shown, and these are provided at the terminal connection portion. It's not necessary.

[0150] The input terminal of this terminal section (the exposed region of the gate electrode layer 116 in Figure 19) An FPC (Flexible Printed Circuit) is connected. Wiring is formed by a conductive film on an organic resin film such as polyimide, and it exhibits anisotropic conductivity. Paste (Anisotropic Conductive Paste; hereafter referred to as ACP) It is connected to the input terminal via (this). A typical ACP uses paper that acts as an adhesive. It is composed of a stone and particles having a conductive surface with a diameter of several tens to several hundred micrometers, plated with gold or the like. The particles mixed into the paste are formed on the conductive layer on the input terminal and on the FPC. By making contact with the conductive layer on the terminal connected to the wiring, an electrical connection can be achieved. can.

[0151] As described above, an EL display device can be manufactured.

[0152] As explained above, the number of photomasks used is reduced, and thin-film transistors and E The number of manufacturing steps for L-display devices can be significantly reduced.

[0153] Furthermore, without going through complex processes such as back-side exposure, registry flow, and lift-off methods, The number of manufacturing steps for thin-film transistors can be significantly reduced. Therefore, complex processes can be eliminated. This eliminates the need for additional steps in the manufacturing process of EL display devices, significantly reducing the number of steps involved.

[0154] Furthermore, while maintaining the electrical characteristics of thin-film transistors, the manufacturing process for thin-film transistors can be significantly improved. It can be reduced in width.

[0155] Furthermore, the above effects make it possible to significantly reduce the manufacturing cost of EL display devices.

[0156] (Embodiment 2) This embodiment shows a display panel or display device manufactured by the method described in Embodiment 1. Electronic equipment incorporating a display unit will be described with reference to Figures 20 to 22. Examples of such electronic devices include cameras such as video cameras or digital cameras. Head-mounted displays (goggle-type displays), car navigation systems, projectors Entrants, car stereos, personal computers, mobile computers (portable information terminals) Examples include mobile phones or e-readers. One example is shown in Figure 20.

[0157] Figure 20(A) shows a television setup. By integrating the EL display panel into the housing, The television apparatus shown in 20(A) can be completed. This will be explained in Embodiment 1. The main screen 223 is formed by a display panel to which the manufacturing method is applied, and other auxiliary equipment The unit is equipped with a speaker section 229, operation switches, and the like.

[0158] As shown in Figure 20(A), the manufacturing method described in Embodiment 1 is applied to the housing 221. A display panel 222 is incorporated, and the receiver 225 begins receiving general television broadcasts. Therefore, by connecting to a wired or wireless communication network via modem 224 Directional (sender to receiver) or two-way (sender and receiver, or between receivers) information exchange It is also possible to make a call. The television equipment is operated by a switch built into the casing or a separate switch. This can be done using the body's remote control device 226, and this remote control device 226 also A display unit 227 for displaying the output information may also be provided.

[0159] Furthermore, in addition to the main screen 223, the television equipment also has a sub-screen 228 as a second display panel. It may also include a configuration that displays the channel, volume, etc.

[0160] Figure 21 shows a block diagram illustrating the main components of the television system. The display panel includes: A pixel section 251 is formed. The signal line driving circuit 252 and the scan line driving circuit 253 are used for display. The panel may be implemented using the COG (Center of Gravity) method.

[0161] Other external circuit configurations include, on the video signal input side, the signal received by tuner 254 Among the components, the video signal amplification circuit 255 amplifies the video signal, and the signal output from there is red. A video signal processing circuit 256 converts the video signal into color signals corresponding to green and blue, and the video signal It has control circuits 257, etc., for converting to the input specifications of the driver IC. The control circuit 257 outputs signals to the scan line side and the signal line side, respectively. In this case, a signal splitting circuit 258 is provided on the signal line side to divide the input digital signal into integers. It would also be acceptable to supply it in this configuration.

[0162] Of the signals received by the tuner 254, the audio signal is sent to the audio signal amplification circuit 259. The output is then supplied to the speaker 263 via the audio signal processing circuit 260. Control circuit 26 Unit 1 receives the receiving station (receiving frequency) and volume control information from the input unit 262, and the tuner 254 and The signal is then sent to the audio signal processing circuit 260.

[0163] Of course, one aspect of the present invention, the EL display device, is not limited to television devices, but also personal devices. This includes computer monitors, information display boards in train stations and airports, and street displays. It can also be applied to large-area display media such as advertising display boards. Therefore, one of the present inventions By applying the manufacturing method for EL display devices described above, the productivity of these display media can be improved. It can be made to happen.

[0164] The method for manufacturing the display device described in Embodiment 1 is applied to the main screen 223 and the sub-screen 228. By using such a display panel or display device, the productivity of the television equipment can be increased. .

[0165] Furthermore, the portable computer shown in Figure 20(B) consists of the main unit 231 and the display unit 232, etc. It has. The display unit 232 is a display panel to which the method for manufacturing the display device described in Embodiment 1 is applied. Computer productivity can be increased by using a display or screen.

[0166] Figure 22 shows an example of a mobile phone, where Figure 22(A) is a front view and Figure 22(B) is a rear view. Figure 22(C) is a front view when the two casings are slid apart. The mobile phone 200 has a casing. It consists of two casings, 201 and casing 202. The mobile phone 200 is a mobile phone and mobile It has the functions of both an information terminal and an information terminal, has a built-in computer, and can do various things in addition to voice calls. It is a so-called smartphone capable of data processing.

[0167] The mobile phone 200 consists of a casing 201 and a casing 202. This includes a display unit 203, a speaker 204, a microphone 205, operation keys 206, and a pointer. The following components are included: a 207 camcorder, a 208 lens for the surface camera, a 209 external connection terminal jack, and an I It is equipped with a headphone jack 210, etc., and the chassis 202 has a keyboard 211, external memory slot It consists of a head 212, a rear camera 213, a light 214, etc. Also, an antenna It is built into the casing 201.

[0168] In addition to the above configuration, the mobile phone 200 also includes a contactless IC chip and a small recording device. It may also have built-in features such as [mention specific features here].

[0169] The overlapping housings 201 and 202 (shown in Figure 22(A)) can be slid apart. This is possible, and by sliding it, it unfolds as shown in Figure 22(C). Display unit 203 This involves a display panel or display device to which the method for manufacturing the display device described in Embodiment 1 is applied. It is possible to embed it. The display unit 203 and the surface camera lens 208 are located on the same surface. Therefore, it can be used as a video phone. Also, the display unit 203 can be used as a viewfinder. By using it in this way, it is possible to capture still images and videos with the rear camera 213 and light 214. be.

[0170] By using speaker 204 and microphone 205, the mobile phone 200 can record voice. It can be used as a recording device or an audio playback device. Also, operation key 20 6 allows for making and receiving phone calls, simple information input operations such as email, and displaying images on the display unit. It is possible to perform operations such as scrolling the screen and moving the cursor to select information to display on the screen. That is the case.

[0171] Furthermore, if you are handling a large amount of information, such as when creating documents or using it as a personal information terminal, a keyboard is recommended. Using code 211 is convenient. Furthermore, the overlapping housings 201 and 202 (Figure 22) By sliding (A), it can be unfolded as shown in Figure 22(C). When used as an information terminal, the keyboard 211 and pointing device 207 Smooth operation is possible using this. External connection terminal jack 209 is for AC adapter and U It can be connected to various cables such as SB cables, and is suitable for charging and connecting to personal computers, etc. Data communication is possible. Also, by inserting a recording medium into the external memory slot 212, This will enable the storage and transfer of large amounts of data.

[0172] The rear side of the housing 202 (Figure 22(B)) is equipped with a rear camera 213 and a light 214. The display unit 203 can be used as a viewfinder to capture both still images and videos.

[0173] In addition to the above functional configuration, it also includes infrared communication functionality, a USB port, and a one-segment TV reception function. It may also be equipped with functions such as a contactless IC chip or an earphone jack.

[0174] The various electronic devices described in this embodiment are thin-film transistors as described in Embodiment 1. Since these electronic devices can be manufactured by applying the manufacturing method for the device and display device, the production of these electronic devices It can improve productivity.

[0175] Therefore, the manufacturing costs of these electronic devices can be significantly reduced. [Explanation of symbols]

[0176] 11. The first transistor 12. Second transistor 13. The third transistor 14 Capacitive elements 15 Light-emitting element 16 gate wiring 17. First power line 18 Source Wiring 19. Second power line 20 common electrode 21 pixels 100 circuit boards 102 First conductive film 104 First insulating film 106 Semiconductor film 108 Impurity Semiconductor Film 110 Second conductive film 112 First Resist Mask 114 Thin film laminate 115 Etched first conductive film 116 Grid control platform 116A Gridgate Layer 116B Grid gate layer 116C Guard gate layer 116D Grid control layer 118 Second Resist Mask 118A Second resist mask 118B Second Resist Mask 118C Second Resist Mask 118D Second Resist Mask 118E Second Resist Mask 118F Second Resist Mask 120 Source electrode and drain electrode layer 120A Source electrode and drain electrode layer 120B Source electrode and drain electrode layer 120C Source electrode and drain electrode layer 120D Source electrode and drain electrode layer 120E Source electrode and drain electrode layer 120F Source electrode and drain electrode layer 122 Source region and drain region 122A Source area and drain area 122B Source area and drain area 122C Source area and drain area 122D Source area and drain area 124 Semiconductor layer 126 First protective film 128 Second protective layer 130 First opening 130A First opening 130B First opening 130C First opening 130D First opening 131 Second opening 132 First pixel electrode layer 132A First pixel electrode layer 132B First pixel electrode layer 132C First pixel electrode layer 133 Bulkhead 134 EL layer 135 Second pixel electrode layer 136 Light-emitting elements 137 Third protective layer 140 Gray Tone Mask 141 circuit boards 142 Light-shielding part 143 Diffraction grating section 145 Halftone Mask 146 circuit boards 147 Semi-transparent part 148 Light-shielding part 160 Third opening 160A Third opening 160B Third opening 161 The fourth opening 170 First Resist Mask 171 Second Resist Mask 200 mobile phones 201 cabinet 202 enclosures 203 Display section 204 speakers 205 Microphone 206 operation keys 207 Pointing devices 208 Lens for surface camera 209 External connection terminal jack 210 Earphone jack 211 keyboard 212 external memory slots 213 Rear camera 214 Light 221 cabinet 222 Display Panel 223 Main screen 224 Modem 225 Receiver 226 Remote control unit 227 Display section 228 Sub-screen 229 Speaker section 231 Main unit 232 Display section 251 pixel section 252 Signal Line Drive Circuit 253 Scan line drive circuit 254 Tuner 255 Video signal amplification circuit 256 Video signal processing circuit 257 Control Circuit 258 Signal splitting circuit 259 Audio signal amplification circuit 260 Audio signal processing circuit 261 Control Circuit 262 Input section 263 speakers

Claims

1. The device has pixels that include first to third transistors, an EL element, and a capacitive element. The source and drain of the first transistor are electrically connected to the first wiring. The source and drain of the first transistor are electrically connected to one electrode of the capacitive element and to the gate of the second transistor. One of the sources and drains of the second transistor is electrically connected to the second wiring. The source and drain of the second transistor are electrically connected to the other electrode of the capacitive element and the EL element. The source and drain of the third transistor are electrically connected to the third wiring. The source and the other drain of the third transistor are electrically connected to the source and the other drain of the second transistor. In a plan view, the first to third wirings have regions extending in the first direction, The second conductive layer, having a region located below the channel formation region of the second transistor, has a region that overlaps with the first conductive layer, which functions as one of the source and drain electrodes of the second transistor, and also functions as one of the electrodes of the capacitive element. In a plan view, the length of the second conductive layer in the first direction is greater than the length of the second conductive layer in the second direction. The second direction is a direction perpendicular to the first direction, The channel directions of each of the first to third transistors intersect the second direction. A display device wherein the semiconductor film having the channel-forming region of the first transistor has a region that overlaps with the second conductive layer and a region that does not overlap with the second conductive layer.

2. The device has pixels that include first to third transistors, an EL element, and a capacitive element. The source and drain of the first transistor are electrically connected to the first wiring. The source and drain of the first transistor are electrically connected to one electrode of the capacitive element and to the gate of the second transistor. One of the sources and drains of the second transistor is electrically connected to the second wiring. The source and drain of the second transistor are electrically connected to the other electrode of the capacitive element and the EL element. The source and drain of the third transistor are electrically connected to the third wiring. The source and the other drain of the third transistor are electrically connected to the source and the other drain of the second transistor. In a plan view, the first to third wirings have regions extending in the first direction, The second conductive layer, having a region located below the channel formation region of the second transistor, has a region that overlaps with the first conductive layer, which functions as one of the source and drain electrodes of the second transistor, and also functions as one of the electrodes of the capacitive element. In a plan view, the length of the second conductive layer in the first direction is greater than the length of the second conductive layer in the second direction. The second direction is a direction perpendicular to the first direction, The channel directions of each of the first to third transistors intersect the second direction. The semiconductor film having the channel-forming region of the first transistor has a region that overlaps with the second conductive layer and a region that does not overlap with the second conductive layer. A third conductive layer is provided, which is made of the same material as the first conductive layer and extends in a second direction in a plan view. The third conductive layer is electrically connected to the semiconductor film, in a display device.

3. A pixel comprising a first to third transistor, an EL element, and a capacitive element, The source and drain of the first transistor are electrically connected to the first wiring. The source and drain of the first transistor are electrically connected to one electrode of the capacitive element and to the gate of the second transistor. One of the sources and drains of the second transistor is electrically connected to the second wiring. The source and drain of the second transistor are electrically connected to the other electrode of the capacitive element and the EL element. The source and drain of the third transistor are electrically connected to the third wiring. The source and the other drain of the third transistor are electrically connected to the source and the other drain of the second transistor. In a plan view, the first to third wirings have regions extending in the first direction, The second conductive layer, having a region located below the channel formation region of the second transistor, has a region that overlaps with the first conductive layer, which functions as one of the source and drain electrodes of the second transistor, and also functions as one of the electrodes of the capacitive element. In a plan view, the first conductive layer has a region extending in the first direction, In a plan view, the second conductive layer has a region extending in the first direction, In a plan view, the semiconductor film having the channel formation region of the first transistor has a region extending in the first direction, The semiconductor film has a region that overlaps with the second conductive layer and a region that does not overlap with the second conductive layer, wherein the semiconductor film is a display device.

4. A pixel comprising a first to third transistor, an EL element, and a capacitive element, The source and drain of the first transistor are electrically connected to the first wiring. The source and drain of the first transistor are electrically connected to one electrode of the capacitive element and to the gate of the second transistor. One of the sources and drains of the second transistor is electrically connected to the second wiring. The source and drain of the second transistor are electrically connected to the other electrode of the capacitive element and the EL element. The source and drain of the third transistor are electrically connected to the third wiring. The source and the other drain of the third transistor are electrically connected to the source and the other drain of the second transistor. In a plan view, the first to third wirings have regions extending in the first direction, The second conductive layer, having a region located below the channel formation region of the second transistor, has a region that overlaps with the first conductive layer, which functions as one of the source and drain electrodes of the second transistor, and also functions as one of the electrodes of the capacitive element. In a plan view, the first conductive layer has a region extending in the first direction, In a plan view, the second conductive layer has a region extending in the first direction, In a plan view, the semiconductor film having the channel formation region of the first transistor has a region extending in the first direction, The semiconductor film has a region that overlaps with the second conductive layer and a region that does not overlap with the second conductive layer. A third conductive layer is provided, which is made of the same material as the first conductive layer and extends in a second direction in a plan view. The third conductive layer is electrically connected to the semiconductor film, in a display device.

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