Indication device

Abstract

To provide a highly flexible display device and a manufacture method of the same.SOLUTION: On a flexible substrate formed are a transistor including a translucent semiconductor film, a capacitive element provided with a dielectric film between a first electrode and a second electrode, and a first insulator film covering the semiconductor film. The capacitive element includes a region where the first electrode contacts the dielectric film, and the first insulator film does not cover the region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, relating to the manufacture or composition of matter, especially One embodiment of the present invention relates to a semiconductor device, a light-emitting device, a display device, and a manufacturing method thereof. do.

[0002] In this specification and the like, a semiconductor device is a device that can function by utilizing semiconductor characteristics. For example, electro-optical devices, display devices, light-emitting devices, semiconductor circuits, transistors, The electronic device may include a semiconductor device. [Background technology]

[0003] In recent years, liquid crystal display devices using liquid crystal elements as display elements, organic EL (electroluminescence) It uses light-emitting elements such as light-emitting diodes (e.g., luminescence, organic light-emitting diodes, or OLEDs). Display devices such as flexible light-emitting display devices have become widespread. Since flexible substrates can improve the display performance, display devices using flexible substrates are being studied.

[0004] A display device using a flexible substrate can be manufactured using a glass substrate or a quartz substrate. After a semiconductor element such as a thin film transistor is fabricated on the substrate, the semiconductor element and the substrate are The organic resin is filled between the glass substrate or quartz substrate and the substrate is transferred to another substrate (e.g., a flexible substrate). A technology has been developed to transpose semiconductor elements onto a substrate (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-174153 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of one embodiment of the present invention is to provide a highly flexible display device and a manufacturing method thereof. Another embodiment of the present invention provides a display device that is not easily broken and a manufacturing method thereof. Another object of one embodiment of the present invention is to provide a lightweight display device and Another object of the present invention is to provide a method for manufacturing a flexible thin film. An object of the present invention is to provide a display device and a manufacturing method thereof.

[0007] Another embodiment of the present invention is to provide a highly reliable display device and a manufacturing method thereof. One of the challenges is to:

[0008] Another object of one embodiment of the present invention is to provide a novel display device and a manufacturing method thereof. The description of these issues does not preclude the existence of other issues. It is not necessary for one embodiment of the present invention to solve all of these problems. Problems other than these will become clear from the description, drawings, claims, etc. It is possible to extract other issues from the description, drawings, claims, etc. do. [Means for solving the problem]

[0009] One embodiment of the present invention is a transistor including a light-transmitting semiconductor film over a flexible substrate. a capacitor element having a first electrode and a second electrode and a dielectric film provided between the first electrode and the second electrode; the capacitance element has a region where the first electrode and the dielectric film are in contact with each other, and the insulating film covers the first electrode and the dielectric film. is a display device characterized in that it does not cover the area.

[0010] One embodiment of the present invention is a transistor including a light-transmitting semiconductor film over a flexible substrate. a capacitor having a first electrode and a second electrode and a dielectric film provided between the first electrode and the second electrode; and a light emitting element. and a first insulating film covering the semiconductor film. The capacitor element has a first electrode and a dielectric film in contact with each other. The display device has a region, and the first insulating film does not cover the region.

[0011] The first electrode is formed on the same surface as the semiconductor film. The light-emitting element emits, for example, white light. In addition, a colored layer can be formed so as to overlap with the light-emitting element.

[0012] The display device may be a top-emission structure, a bottom-emission structure, or a dual-missive structure. It can be an optional structure. [Effects of the Invention]

[0013] The display device can be easily bent. Even if the display panel is folded over, it is less likely to break, making it possible to realize a highly reliable display device. It is possible.

[0014] According to one embodiment of the present invention, a highly flexible display device and a manufacturing method thereof can be provided. can.

[0015] According to one embodiment of the present invention, there is provided a display device with high reliability and a manufacturing method thereof. can be done.

[0016] According to one embodiment of the present invention, a novel display device and a manufacturing method thereof can be provided. . [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view illustrating one embodiment of a display device. [Figure 2] 1A and 1B are cross-sectional views illustrating one embodiment of a display device. [Figure 3] 1A and 1B are a block diagram and a circuit diagram illustrating one embodiment of a display device. [Figure 4] 1A to 1C are cross-sectional views illustrating one embodiment of a manufacturing method of a display device. [Figure 5] 1A to 1C are cross-sectional views illustrating one embodiment of a manufacturing method of a display device. [Figure 6] 1A to 1C are cross-sectional views illustrating one embodiment of a manufacturing method of a display device. [Figure 7] 1A to 1C are cross-sectional views illustrating one embodiment of a manufacturing method of a display device. [Figure 8] 1A to 1C are cross-sectional views illustrating one embodiment of a manufacturing method of a display device. [Figure 9] 1A to 1C are cross-sectional views illustrating one embodiment of a manufacturing method of a display device. [Figure 10] 1A to 1C are cross-sectional views illustrating one embodiment of a manufacturing method of a display device. [Figure 11] 1A to 1C are cross-sectional views illustrating one embodiment of a manufacturing method of a display device. [Figure 12] 1A to 1C are cross-sectional views illustrating one embodiment of a manufacturing method of a display device. [Figure 13] 1A and 1B are cross-sectional views illustrating one embodiment of a display device. [Figure 14] 1A to 1C illustrate one embodiment of a transistor. [Figure 15] 1A to 1C illustrate one embodiment of a transistor. [Figure 16] 1A to 1C illustrate one embodiment of a transistor. [Figure 17] 1A and 1B are diagrams illustrating band structures of transistors. [Figure 18] 1A to 1C illustrate a configuration example of a light-emitting element. [Figure 19] 1A to 1C illustrate examples of electronic devices and lighting devices. [Figure 20] 1A to 1C illustrate examples of electronic devices. [Figure 21] 1A and 1B are cross-sectional views illustrating one embodiment of a display device. [Figure 22] 1A and 1B are cross-sectional views illustrating one embodiment of a display device. [Figure 23] 1A and 1B are cross-sectional views illustrating one embodiment of a display device. [Figure 24] 1A and 1B are cross-sectional views illustrating one embodiment of a display device. DETAILED DESCRIPTION OF THE INVENTION

[0018] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description. The present invention is not limited to the above embodiments, and various changes and modifications may be made in the form and details thereof without departing from the spirit and scope of the present invention. It will be readily understood by those skilled in the art that the present invention can be achieved by the following embodiments. It should not be construed as being limited to the contents of the description. The same reference numerals are used in different drawings to denote the same parts or parts having similar functions. A repeated explanation will be omitted.

[0019] In each drawing described in this specification, the size of each component, the thickness of a layer, or the area is The figures may be exaggerated or abbreviated for clarity. In particular, in the top view, some components are not shown in order to make the drawing easier to understand. The description may be omitted.

[0020] In addition, the position, size, range, etc. of each component shown in the drawings are for the purpose of facilitating understanding of the invention. Therefore, the actual location, size, range, etc. may not be shown. The invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings. In the actual manufacturing process, resist masks, etc., may be unintentionally damaged by etching or other processes. However, in order to make it easier to understand, it may be omitted.

[0021] In order to make the drawings easier to understand, especially in top views (also called "plan views"), Description of some components may be omitted.

[0022] In this specification, ordinal numbers such as "first" and "second" are used to avoid confusion of components. It does not indicate any order or ranking such as the order of processes or stacking. In addition, even if a term is not accompanied by an ordinal number in this specification, etc., it is possible to avoid confusion of the constituent elements. To avoid this, ordinal numbers may be used in the claims.

[0023] In addition, the terms "electrode" and "wiring" used in this specification and the like do not limit the functionality of these components. For example, an "electrode" may be used as part of a "wiring." Furthermore, the terms "electrode" and "wiring" are used interchangeably to refer to the plural "electrodes" and "wirings." This also includes cases where the "line" is formed as a single unit.

[0024] In this specification, the terms "above" and "below" refer to the positional relationship of components directly above or below each other. For example, "electrode on insulating layer A" is not limited to being below and in direct contact with the insulating layer A. If the expression is "B", electrode B does not need to be formed directly on insulating layer A, The inclusion of other components between the edge layer A and the electrode B is not excluded.

[0025] The source and drain functions may also be different when using transistors with different polarities or when using circuits When the direction of the current changes during circuit operation, they are interchanged depending on the operating conditions. Therefore, it is difficult to determine which is the source and which is the drain. In this specification, the terms source and drain may be used interchangeably. Let's say.

[0026] In addition, in this specification, "electrically connected" means "something that has some kind of electrical effect." This includes cases where the device is connected via a " is not subject to any particular restrictions as long as it enables the transmission and reception of electrical signals between connected objects. Therefore, even when it is expressed as "electrically connecting," in an actual circuit, In some cases, there are no physical connections and only wires running.

[0027] In this specification, "parallel" means that two straight lines are at an angle of -10° or more and 10° or less. Therefore, it includes the case where the angle is between -5° and 5°. "Straight" and "orthogonal" mean that two straight lines are arranged at an angle of 80° or more and 100° or less. Therefore, it includes cases where the angle is between 85° and 95°.

[0028] In addition, in this specification, when an etching process is performed after a photolithography process, In this case, unless otherwise specified, the resist mask formed in the photolithography process is It shall be removed after the etching process is completed.

[0029] (Embodiment 1) In this embodiment, a semiconductor device according to one embodiment of the present invention and a manufacturing method thereof will be described with reference to the drawings. FIG. 1A is a perspective view of a display device 100. The display device 100 is a light-emitting display device that uses light-emitting elements as display elements. The display device 100 shown in this embodiment is flexible, and as shown in FIGS. 2 shows the curve indicated by the dashed line A1-A2 in FIG. 1(A). FIG.

[0030] <Display device configuration> The display device 100 illustrated in this embodiment includes a display area 131, a first driving circuit 132, a second driving circuit 133, a third driving circuit 134, a fourth driving circuit 135, a fifth driving circuit 136, a sixth driving circuit 137, a sixth driving circuit 138, a sixth driving circuit 139 ... The display area 131, the first drive circuit 132, and the second drive circuit 133 are The driving circuit 133 is composed of a plurality of transistors. For example, the second driving circuit 1 The display device 100 is also configured with a plurality of transistors 233. The light-emitting element 125 includes the electrode 115, the EL layer 117, and the electrode 118, and the terminal electrode 116. A plurality of light emitting elements 125 are formed in the display area 131. In the first place, a transistor 231 (not shown) that controls the amount of light emitted by the light emitting element 125 is electrically connected to the In addition, a capacitor 232 is electrically connected to the transistor 231. The transistor 231 also includes a transistor that can supply a data signal. 431 are electrically connected.

[0031] The first driving circuit 132 and the second driving circuit 133 are connected to the external electrode 124. A function of supplying a signal to a specific light emitting element 125 in the display area 131 at a specific timing. Has.

[0032] In addition, the display device 100 has a substrate 111 and a substrate 121 bonded together via an adhesive layer 120. An insulating film 205 is formed on a substrate 111 via an adhesive layer 112. The insulating film 205 is made of silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, or silicon oxide. Aluminum oxide, aluminum oxynitride, or aluminum oxynitride, etc., is used as a single layer. Alternatively, it is preferable to form the insulating film 205 in a multi-layer structure. The film can be formed by an oxidation method, a coating method, a printing method, or the like.

[0033] The insulating film 205 functions as a base layer, and prevents the transistor from being exposed to the substrate 111, adhesive layer 112, etc. This can prevent or reduce the diffusion of impurity elements into the photoresist or light emitting element.

[0034] The substrates 111 and 121 are made of organic resin material or glass having a thickness sufficient to provide flexibility. The display device 100 may have a so-called bottom emission structure (lower surface In the case of a display device of a double-side emission type, an EL element is formed on the substrate 111. A material that is transparent to light emitted from the layer 117 is used. In the case of a light-emitting display device or a dual-side light-emitting display device, an EL layer 1 is formed on the substrate 121. A material that is transparent to light emitted from 17 is used.

[0035] The substrate 121 and the substrate 111 may be flexible and transparent to visible light. The materials include polyethylene terephthalate resin and polyethylene naphthalate resin. , polyacrylonitrile resin, polyimide resin, polymethyl methacrylate resin, polycarbonate Carbonate resin, polyethersulfone resin, polyamide resin, cycloolefin resin , polystyrene resin, polyamide-imide resin, polyvinyl chloride resin, etc. Non-transparent substrates include stainless steel substrates and stainless steel foils. There are substrates with tungsten foil, tungsten substrates, and substrates with tungsten foil.

[0036] In addition, the substrate 121 and the substrate 111 may be made of polypropylene, polyester, or polyfluoride. vinyl chloride, polyvinyl chloride, polyamide, polyimide, inorganic vapor deposition film, paper, etc. Alternatively, cellophane substrate, stone substrate, wood substrate, cloth substrate (natural fiber) Fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester), regenerated fibers (a acetate, cupro, rayon, recycled polyester), leather substrate, or rubber A substrate or the like can also be used.

[0037] The thermal expansion coefficient of the substrate 121 and the substrate 111 is preferably 30 ppm / K or less, and more preferably 10 ppm / K or less. More preferably, the concentration is 10 ppm / K or less. In advance, a film containing nitrogen and silicon such as silicon nitride or silicon oxynitride, or a film containing aluminum nitride or the like is prepared. A protective film with low water permeability, such as a film containing nitrogen and aluminum, may be formed. The substrate 121 and the substrate 111 are structures in which a fibrous body is impregnated with an organic resin (so-called plastics). (also called repreg) may also be used.

[0038] By using such a substrate, it is possible to provide a display device that is less likely to break. This can provide a lightweight display device. Alternatively, it can provide a display device that is easy to bend. This can be done.

[0039] In addition, the transistor 231, the transistor 431, the capacitor 232, and the transistor 233 The terminal electrode 116 is formed on an insulating film 205 (see FIG. 2). In this embodiment, the transistor 431 and the transistor 233 are connected to a transistor An example of a dual-gate transistor with a structure in which a semiconductor layer is sandwiched between two gate electrodes However, the transistor 431 and the transistor 233 are connected in a single gate. For example, the transistor 431 and the transistor Transistor 233 includes channel protection transistors and top gate transistors. It is also possible to use a filter or the like.

[0040] The transistor 231, which is not shown in FIG. 2, also has the same structure as the other transistors. In addition, the transistor 231, the transistor 431, and the transistor 233 may have the same structure or a different structure. The size of the transistor (e.g., channel length and channel width) is It can be adjusted appropriately.

[0041] The transistor 431 and the transistor 233 are formed by a gate electrode 206, a gate insulating film 20 7, an oxide semiconductor film 208, a source electrode 209a, and a drain electrode 209b.

[0042] In addition, the insulating film 108 is formed over the transistor 431 and the transistor 233. An insulating film 109 is formed on the film 108, and an insulating film 110 is formed on the insulating film 109. The insulating film 110 functions as a protective insulating layer, and prevents the layers above the insulating film 110 from passing through the transistor. Prevent or reduce the diffusion of impurity elements into the capacitor 431 and the transistor 233. It is possible.

[0043] In addition, in a region that does not overlap with the transistor 431 and the transistor 233, The insulating film 108 and the insulating film 109 are partially removed. By removing it, the display device 100 can be made easier to bend.

[0044] An insulating film 211 is formed on the insulating film 110. In order to reduce surface irregularities, the insulating film 211 may be subjected to planarization treatment. However, the polishing treatment (for example, chemical mechanical polishing) is not particularly limited. This is done by chemical polishing (CMP) or dry etching. It is possible to do so.

[0045] Furthermore, on the insulating film 211, the light emitting element 125 and another light emitting element adjacent to the light emitting element 125 are formed. A partition wall 114 is formed to separate the electrodes 125 .

[0046] The substrate 121 is also provided with a light-shielding film 264, a colored layer 266, and an overcoat layer 268. The display device 100 reflects light 235 emitted from the EL layer 117 through the colored layer 2. 66, which emits light from the substrate 121 side, a so-called top emission structure (top emission structure). It is a display device.

[0047] The light emitting element 125 is made up of an insulating film 211, an insulating film 110, an insulating film 109, and an insulating film 111. In the opening provided in 08, the transistor 231 is electrically connected through the wiring 241. It has been done.

[0048] The insulating film 211, the insulating film 110, the insulating film 109, and the insulating film 116 overlap each other. The external electrode 124 and the terminal electrode 116 are electrically connected through an opening in the insulating film 108. The external electrodes 124 are electrically connected via a connection layer 123. For example, FP C can be used.

[0049] The anisotropic conductive connection layer 123 is a known anisotropic conductive film (ACF). Conductive Film) and Anisotropic Conductive Paste (ACP) It can be formed using a tungsten carbide (Tropical Conductive Paste) or the like.

[0050] The anisotropic conductive connection layer 123 is made of a thermosetting resin or a thermosetting and photosetting resin containing conductive particles. The anisotropic conductive connection layer is made by hardening a paste or sheet-like material that has been mixed. The anisotropic conductive connection layer 123 becomes a material that exhibits anisotropic conductivity when irradiated with light or subjected to thermocompression bonding. The conductive particles used in 123 are, for example, spherical organic resin particles coated with Au, Ni, Co, etc. Particles coated with a thin film of metal can be used.

[0051] The external electrode 124 and the terminal electrode 116 are electrically connected via the anisotropic conductive connection layer 123. This makes it possible to input power and signals to the display device 100.

[0052] As shown in FIG. 21, a touch sensor may be formed on the substrate 121. As the sensor, various types such as a resistance type, a capacitance type, and an optical sensor type can be used. As shown in FIG. 21, an electrode 910a for the touch sensor and an electrode 910b for the touch sensor are , are connected via wiring 912. To prevent this, an insulating layer 911 is provided thereon. a, 910b, and 910c are made of indium tin oxide or indium zinc oxide to allow light to pass through. It is desirable that the wiring 912 is formed of a transparent conductive film such as an oxide. Since the area covered by the glass is small, it is possible to use a non-transparent conductive material such as Al, Mo, Ti, W, etc. It can be constructed using a single layer or multilayer film made of indium tin oxide or A transparent conductive film such as indium zinc oxide may be used. By directly forming the touch sensor, it is possible to prevent misalignment when the display device 100 is bent. It has the advantage of being less likely to occur.

[0053] On the substrate 121, optical sheets such as a polarizing plate and a retardation plate may be provided.

[0054] It is also possible to provide a touch sensor on a substrate other than the substrate 121. This shows an example in which a touch sensor is provided on a surface other than the substrate 121. is the outermost substrate and corresponds to the cover of the display device 100. The cover is operated by directly touching it with a human finger or a touch pen. For example, a touch sensor is provided on the back side of the substrate 921. The adhesive layer 920 is provided between the adhesive layer 120 and the adhesive layer 120. This allows the display device 100 to bend without any misalignment. In addition, since there is no air layer between the two, external light is less likely to be reflected. This also has the advantage of improving visibility.

[0055] When the display device 100 is used in a bent state, the substrate 921 is It is desirable that the display device 100 is made of the same material as that of the display device 1. However, it is desirable that the display device 100 is made of the same material as that of the display device 1. Taking advantage of this, when the display device 100 is not used in a bent state, the substrate 921 is made of glass. A substrate may be used. In particular, chemically treated tempered glass is used, which is resistant to scratches. Therefore, it is possible to construct a durable display device. For example, It is possible to use glass made of such a material. Therefore, even if it is dropped, it is unlikely to break, and it is possible to construct a durable display device. Yes, it is possible.

[0056] <Pixel circuit configuration example> Next, a more specific example of the configuration of the display device 100 will be described with reference to FIG. 1 is a block diagram for explaining the configuration of a display device 100. The display device includes a display area 131, a first driving circuit 132, and a second driving circuit 133. The circuit 132 functions as, for example, a scanning line driver circuit. For example, it functions as a signal line driver circuit.

[0057] The display devices 100 are arranged substantially parallel to each other and are driven by a first driving circuit 132. m scanning lines 135 whose potentials are controlled by a second driving and n signal lines 136 whose potentials are controlled by a circuit 133. The area 131 has a plurality of pixels 134 arranged in a matrix. The first drive circuit 132 and the second drive circuit 133 may be collectively referred to as a drive circuit unit.

[0058] Each scanning line 135 is connected to one of the pixels 134 arranged in m rows and n columns in the display area 131. The signal lines 136 are electrically connected to the n pixels 134 arranged in any row. is m pixels 134 arranged in any one of the columns among the pixels 134 arranged in m rows and n columns. 4. Both m and n are integers of 1 or greater.

[0059] 3B and 3C show a pixel 134 of the display device shown in FIG. 3A. The circuit configuration shown is as follows:

[0060] [Example of a pixel circuit for a light-emitting display device] The pixel 134 shown in FIG. 3B includes a transistor 431, a capacitor 232, and a transistor The light-emitting element 125 includes a transistor 231 and a light-emitting element 125 .

[0061] One of the source electrode and the drain electrode of the transistor 431 is connected to a transistor Further, the transistor 431 is electrically connected to a line (hereinafter referred to as a signal line DL_n). The gate electrode is electrically connected to the wiring (hereinafter referred to as the scanning line GL_m) to which the gate signal is given. is connected to.

[0062] The transistor 431 is turned on or off to connect the node of the data signal 435.

[0063] One of the pair of electrodes of the capacitor 232 is a wiring to which a specific potential is applied (hereinafter, a potential supply line VL_a) and the other is electrically connected to node 435. The other of the source and drain electrodes of transistor 431 is electrically connected to node 435. are connected to the network.

[0064] The capacitor 232 functions as a storage capacitor that stores data written to the node 435. It has.

[0065] One of the source electrode and the drain electrode of the transistor 231 is electrically connected to the potential supply line VL_a. Additionally, the gate electrode of transistor 231 is electrically connected to node 435. Connected.

[0066] One of the anode and the cathode of the light emitting element 125 is electrically connected to the potential supply line VL_b. The other end is electrically connected to the other of the source electrode and the drain electrode of the transistor 231. can be.

[0067] The light emitting element 125 may be, for example, an organic electroluminescence element (also called an organic EL element). However, the light emitting element 125 is not limited to this, and An inorganic EL element made of an inorganic material may also be used.

[0068] A high power supply potential VDD is applied to one of the potential supply lines VL_a and VL_b. and the other is supplied with a low power supply potential VSS.

[0069] In the display device having the pixels 134 of FIG. 3B, the first driver circuit 132 drives the pixels of each row. 134 is selected in turn, and transistor 431 is turned on to apply the data signal to node 435. Write.

[0070] In the pixel 134 in which data is written to the node 435, the transistor 431 is turned off. Furthermore, the transistor 435 is turned on in response to the potential of the data written to the node 435. The amount of current flowing between the source electrode and the drain electrode of the transistor 231 is controlled, and a light emitting element is formed. 125 emits light at a brightness that corresponds to the amount of current flowing. You can display the image.

[0071] [An example of a pixel circuit for a liquid crystal display device] The pixel 134 shown in FIG. 3C includes a liquid crystal element 432, a transistor 431, and a capacitor 2. 32 and has.

[0072] The potential of one of the pair of electrodes of the liquid crystal element 432 is set appropriately according to the specifications of the pixel 134. The alignment state of the liquid crystal element 432 is determined by data written to the node 436 . Note that one of the pair of electrodes of the liquid crystal element 432 included in each of the plurality of pixels 134 is connected to a common In addition, a potential (common potential) may be applied to one of the liquid crystal elements 432 for each pixel 134 in each row. A different potential may be applied to one of the pair of electrodes.

[0073] For example, the display device including the liquid crystal element 432 can be driven in TN mode, STN mode, or the like. Mode, VA mode, ASM (Axially Symmetric Aligned Mix cro-cell mode, OCB (Optically Compensated B refrigeration mode, FLC (Ferroelectric Liquid d Crystal) mode, AFLC (AntiFerroelectric Liq. Crystal) mode, MVA mode, PVA (Patterned Ver Artificial Alignment mode, IPS mode, FFS mode, or TBA (Transverse Bend Alignment) mode may also be used. In addition to the above-mentioned driving method, the display device can also be driven by an ECB (Electric Carrier Board) or the like. Ally Controlled Birefringence mode, PDLC (P Polymer Dispersed Liquid Crystal (PNLC) mode (Polymer Network Liquid Crystal) mode, guest However, there are various types of liquid crystal elements and their driving methods, and they are not limited to these. A variety of materials can be used.

[0074] In addition, a liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent The liquid crystal element 432 may be configured by the above. The liquid crystal that exhibits the blue phase has a response speed of 1 msec or more. It is optically isotropic, so alignment treatment is unnecessary and viewing angle dependency is small. stomach.

[0075] As the display element, a display element other than the light emitting element 125 and the liquid crystal element 432 is used. For example, electrophoretic elements, electronic inks, and electrophoretic display elements can be used as display elements. Wetting elements, MEMS (microelectromechanical systems), digital Micromirror Device (DMD), DMS (Digital Micro Shutter), M IRASOL®, an IMOD (Interference Modulation) element It is also possible to use the following.

[0076] In the pixel 134 in the mth row and the nth column, the source electrode and the drain electrode of the transistor 431 One is electrically connected to the signal line DL_n, and the other is electrically connected to the node 436. The gate electrode of the transistor 431 is electrically connected to the scanning line GL_m. By being in an on or off state, the data signal to node 436 is transmitted. It has the function of controlling the writing of

[0077] One of the pair of electrodes of the capacitor 232 is connected to a wiring to which a specific potential is supplied (hereinafter, referred to as a capacitor line CL ) and the other is electrically connected to node 436. The other of the pair of electrodes of 32 is electrically connected to a node 436. The value of is set appropriately according to the specifications of the pixel 134. The capacitance element 232 is connected to the node 436. It functions as a storage capacitor that stores written data.

[0078] For example, in a display device having the pixel 134 shown in FIG. 3C, the first driver circuit 132 The pixels 134 in the row are selected in sequence, and transistor 431 is turned on to supply data to node 436. Write the data signal.

[0079] In the pixel 134 in which the data signal is written to the node 436, the transistor 431 is in the off state. By repeating this for each row, an image can be displayed.

[0080] <Example of manufacturing method> Next, an example of a method for manufacturing the display device 100 will be described with reference to the cross-sectional views of FIGS. 4 to 12. 4 to 12 correspond to cross sections of the display area 131 in FIG.

[0081] [Forming a release layer] First, a release layer 113 is formed on an element formation substrate 101 (see FIG. 4(A)). The substrate 101 may be a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, A metal substrate or the like can be used. A plastic substrate having such a structure may also be used.

[0082] The glass substrate may be made of, for example, aluminosilicate glass or aluminoborosilicate glass. Glass materials such as barium borosilicate glass are used. By adding more BaO, a more practical heat-resistant glass can be obtained. Russ etc. can be used.

[0083] The release layer 113 may be made of tungsten, molybdenum, titanium, tantalum, niobium, nickel, or copper. Baltic, Zirconium, Ruthenium, Rhodium, Palladium, Osmium, Iridium, An element selected from silicon, or an alloy material containing the element, or a chemical compound containing the element The insulating film can be formed by using a composite material. The crystalline structure of the separation layer 113 may be amorphous, microcrystalline, or polycrystalline. The peeling layer 113 may be formed of aluminum oxide, gallium oxide, zinc oxide, or Titanium oxide, indium oxide, indium tin oxide, indium zinc oxide, or In It can also be formed using a metal oxide such as GaZnO (IGZO).

[0084] The peeling layer 113 can be formed by a sputtering method, a CVD method, a coating method, a printing method, or the like. The coating method includes a spin coating method, a droplet ejection method, and a dispense method.

[0085] When the peeling layer 113 is formed as a single layer, it is preferably made of tungsten, molybdenum, or a combination of tungsten and molybdenum. It is preferable to use an alloy material containing molybdenum. Alternatively, the peeling layer 113 may be formed as a single layer. In this case, tungsten oxide or oxynitride, molybdenum oxide or oxide Nitrides, or oxides or oxynitrides of alloys containing tungsten and molybdenum It is preferable that

[0086] The peeling layer 113 may be a layer containing tungsten and a layer containing an oxide of tungsten. When a stacked structure of layers containing tungsten is formed, an oxide insulating film is formed in contact with the layer containing tungsten. As a result, tungsten oxide is formed at the interface between the tungsten-containing layer and the oxide insulating film. Alternatively, the surface of the layer containing tungsten may be subjected to a thermal oxidation treatment, an oxygen plating treatment, or the like. The material is treated with a strong oxidizing solution such as ozonated water or ozone water to remove tungsten oxides. A layer containing the metal may be formed.

[0087] In this embodiment mode, tungsten is formed as the peeling layer 113 by a sputtering method. .

[0088] [Forming the base layer] Next, an insulating film 205 is formed as a base layer over the peeling layer 113 (see FIG. 4(A)). The insulating film 205 may be made of silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, or silicon oxide. aluminum nitride, aluminum oxynitride, aluminum nitride oxide, etc., as a single layer or It is preferable to form the insulating film 205 in a multi-layer structure. The insulating film 205 can be formed by a method such as sputtering, CVD, or thermal oxidation. The conductive layer can be formed by a coating method, a printing method, or the like.

[0089] The thickness of the insulating film 205 is 30 nm or more and 500 nm or less, preferably 50 nm or more and 400 nm or less. It is sufficient to set it to m or less.

[0090] The insulating film 205 prevents diffusion of impurity elements from the substrate 111 and the adhesive layer 112 to the light emitting element 125. In this embodiment, the insulating film 205 is a plasma insulating film. A silicon oxide film having a thickness of 200 nm is formed by the micro-CVD method.

[0091] [Forming the gate electrode] Next, a gate electrode 206 is formed on the insulating film 205 (see FIG. 4(A)). Gate electrode 206 is made of aluminum, chromium, copper, tantalum, titanium, molybdenum, and tungsten. or an alloy containing the above metal elements, or It can be formed by using a combination of alloys, etc. Also, manganese, zirconium, etc. The gate electrode 206 may be formed of one or more metal elements selected from the above. The film may have a single layer structure or a laminated structure of two or more layers. a single-layer structure of aluminum film, a two-layer structure of aluminum film laminated on titanium film, a titanium nitride film laminated on titanium film, Two-layer structure with a titanium film laminated on top, two-layer structure with a tungsten film laminated on top of a titanium nitride film, nitride Two-layer structure in which a tungsten film is laminated on a tantalum film or a tungsten nitride film, titanium film A two-layer structure with a copper film laminated on top, a titanium film, and an aluminum film laminated on top of the titanium film. There are also three-layer structures in which a titanium film is formed on top of the aluminum. Elements selected from tantalum, tungsten, molybdenum, chromium, neodymium, and scandium A pure film, an alloy film made by combining a plurality of films, or a nitride film may be used.

[0092] The gate electrode 206 is made of indium tin oxide, indium oxide containing tungsten oxide. oxide, indium zinc oxide with tungsten oxide, indium oxide with titanium oxide Indium tin oxide, indium zinc oxide, silicon oxide containing titanium oxide A light-transmitting conductive material such as indium tin oxide can also be used. A laminated structure of the above-mentioned light-transmitting conductive material and the above-mentioned metal element may also be used.

[0093] First, the gate electrode 20 is formed on the insulating film 205 by sputtering, CVD, vapor deposition, or the like. A conductive film to be the layer 6 is laminated, and a resist mask is formed on the conductive film by a photolithography process. Next, a part of the conductive film that will become the gate electrode 206 is etched using a resist mask. The gate electrode 206 is formed by etching. At this time, other wirings and electrodes are also formed at the same time. It is possible.

[0094] The etching of the conductive film may be performed by dry etching or wet etching, or both. When dry etching is used, the resist mask may be If an ashing process is performed before removing the resist mask, it becomes easier to remove the resist mask using a stripping solution. It can be said that:

[0095] The gate electrode 206 may be formed by electrolytic plating, printing, inkjet printing, or the like instead of the above-mentioned method. It may also be formed by a jet method or the like.

[0096] The thickness of the gate electrode 206 is 5 nm or more and 500 nm or less, and more preferably 10 nm or more and 300 nm or less. 00 nm or less, and more preferably 10 nm or more and 200 nm or less.

[0097] Furthermore, by forming the gate electrode 206 using a conductive material having a light-shielding property, the gate electrode 206 can be protected from external light. This can make it difficult for light from the gate electrode 206 side to reach the oxide semiconductor film 208. As a result, fluctuations in the electrical characteristics of the transistor due to light irradiation can be suppressed.

[0098] [Forming the gate insulating film] Next, a gate insulating film 207 is formed (see FIG. 4(A)). For example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide aluminum, a mixture of aluminum oxide and silicon oxide, hafnium oxide, gallium oxide or A Ga-Zn-based metal oxide or the like may be used, and the layer may be a laminate or a single layer.

[0099] The gate insulating film 207 is made of hafnium silicate (HfSiO x ), nitrogen added Hafnium silicate (HfSi x O y N z ), nitrogen-doped hafnium aluminium Laminate (HfAl x O y N z ), hafnium oxide, yttrium oxide, etc. The use of high-k materials can reduce the gate leakage of transistors. A laminate of carbon and hafnium oxide may also be used.

[0100] The thickness of the gate insulating film 207 is 5 nm or more and 400 nm or less, and more preferably 10 nm or more. It is preferable to set the thickness to 300 nm or less, and more preferably to set the thickness to 50 nm or more and 250 nm or less.

[0101] The gate insulating film 207 can be formed by a sputtering method, a CVD method, a vapor deposition method, or the like. .

[0102] The gate insulating film 207 is a silicon oxide film, a silicon oxynitride film, or a silicon nitride oxide film. When forming a silicon film, a deposition gas containing silicon and an oxidizing gas are used as source gases. Representative examples of silicon-containing deposition gases include silane, disilane, Examples of oxidizing gases include trisilane, fluorinated silane, etc. Examples of oxidizing gases include oxygen, ozone, and nitrous oxide. , nitrogen dioxide, etc.

[0103] The gate insulating film 207 is made of a nitride insulating film and an oxide insulating film in this order from the gate electrode 206 side. By providing a nitride insulating film on the gate electrode 206 side, Impurities from the gate electrode 206 side, typically hydrogen, nitrogen, alkali metal, or aluminum, This can prevent potassium earth metals and the like from migrating to the oxide semiconductor film 208. By providing an oxide insulating film on the oxide semiconductor film 208 side, the gate insulating film 207 and the oxide semiconductor It is possible to reduce the defect level at the interface of the film 208. As a result, the deterioration of the electrical characteristics can be prevented. Note that the oxide insulating film may have a stoichiometric composition. When an oxide insulating film containing more oxygen than the oxygen that satisfies the composition of the gate insulating film is used, Therefore, the defect level at the interface between the oxide semiconductor film 207 and the oxide semiconductor film 208 can be further reduced. This is preferable.

[0104] When the gate insulating film 207 is a laminate of a nitride insulating film and an oxide insulating film as described above, In this case, it is preferable to make the nitride insulating film thicker than the oxide insulating film.

[0105] Since the nitride insulating film has a higher dielectric constant than the oxide insulating film, the thickness of the gate insulating film 207 is Even if the thickness is increased, the electric field generated in the gate electrode 206 can be efficiently transmitted to the oxide semiconductor film 208. In addition, by making the entire gate insulating film 207 thick, the insulation of the gate insulating film 207 can be improved. The edge breakdown voltage can be increased, and the reliability of the semiconductor device can be improved.

[0106] The gate insulating film 207 is made of a first nitride insulating film having few defects and a hydrogen blocking property. A second nitride insulating film having a high resistance and an oxide insulating film are stacked in this order from the gate electrode 206 side. The gate insulating film 207 can have a laminated structure in which a first nitride insulating film having few defects is formed. By using the film, the dielectric strength of the gate insulating film 207 can be improved. By providing a second nitride insulating film having high hydrogen blocking properties on the gate insulating film 207, Hydrogen contained in the gate electrode 206 and the first nitride insulating film moves to the oxide semiconductor film 208. This can prevent this from happening.

[0107] An example of a method for forming the first nitride insulating film and the second nitride insulating film is shown below. By using a plasma CVD method with a mixture of orthogonal, nitrogen, and ammonia gas as the source gas, Then, a silicon nitride film with few defects is formed as the first nitride insulating film. By switching to a mixture of silane and nitrogen, the hydrogen concentration is low and hydrogen is blocked. A silicon nitride film that can be formed by this method is deposited as the second nitride insulating film. By this method, a nitride insulating film having few defects and a hydrogen blocking property is laminated. Further, the gate insulating film 207 can be formed.

[0108] The gate insulating film 207 is made of a third nitride insulating film having a high impurity blocking property and a defect-resistant film. A first nitride insulating film with few defects, a second nitride insulating film with high hydrogen blocking properties, and an oxide The insulating film may have a laminated structure in which the insulating film and the oxide insulating film are laminated in this order from the gate electrode 206 side. The gate insulating film 207 is provided with a third nitride insulating film having high impurity blocking properties. The impurities from the gate electrode 206, typically hydrogen, nitrogen, alkali metals, or alkali metals, The alkali-earth metal and the like can be prevented from moving to the oxide semiconductor film 208.

[0109] An example of a method for forming the first to third nitride insulating films will be described below. The plasma CVD method was performed using a mixture of silane, nitrogen, and ammonia as the source gas. Therefore, a silicon nitride film having high impurity blocking properties is formed as the third nitride insulating film. Next, by increasing the flow rate of ammonia, a silicon nitride film with fewer defects was obtained. Next, the source gas is switched to a mixed gas of silane and nitrogen. The second silicon nitride film has a low hydrogen concentration and is capable of blocking hydrogen. This method of formation results in a film with few defects and no impurities. The gate insulating film 207 is formed by stacking a nitride insulating film having blocking properties. can.

[0110] When a gallium oxide film is formed as the gate insulating film 207, MOCVD (Metal Organic Chemical Vapor Deposition (OCVD) method It can be formed by

[0111] Note that the oxide semiconductor film 208 in which the channel of the transistor is formed and the hafnium oxide film An insulating film containing hafnium oxide is stacked on top of the insulating film containing hafnium oxide via an oxide insulating film. By doing so, the threshold voltage of the transistor can be changed.

[0112] [Forming an oxide semiconductor film] Next, the oxide semiconductor film 208 in which a channel is to be formed and one electrode of the capacitor 232 are formed. An oxide semiconductor film 209 functioning as a gate insulating film is formed over the gate insulating film 207 (see FIG. 4B). The oxide semiconductor film 208 and the oxide semiconductor film 209 are typically made of In -Ga oxide, In-Zn oxide, In-M-Zn oxide (M is Al, Ga, Y, Zr, La, Ce, or Nd) can be used.

[0113] When the oxide semiconductor film 208 is an In-M-Zn oxide, the sum of In and M is 1 When the atomic ratio of In and M is 0.00 atomic %, the atomic ratio of In is preferably 25 atomic %. mic% or more, M is less than 75 atomic%, and more preferably In is 34 atomic% or more. c% or more, and M is less than 66 atomic%.

[0114] In particular, the oxide semiconductor film 208 has an energy gap of 2 eV or more, preferably 2.5 eV or more. More preferably, the energy gap is 3 eV or more. By using a semiconductor, the off-state current of a transistor can be reduced.

[0115] The oxide semiconductor film 208 and the oxide semiconductor film 209 each have a thickness of 3 nm or more and 200 nm or less. Preferably, the thickness is 3 nm or more and 100 nm or less, and more preferably, 3 nm or more and 50 nm or less. do.

[0116] The oxide semiconductor film 208 and the oxide semiconductor film 209 are made of In-M-Zn oxide (M is Al, In the case of In-M-Zn oxides (Ga, Y, Zr, La, Ce, or Nd), The atomic ratio of the metal elements in the sputtering target used for this purpose satisfies In≧M, Zn>M. It is preferable that the atomic ratio of the metal elements in such a sputtering target is , In:M:Zn=1:1:1, In:M:Zn=5:5:6, In:M:Zn=2:1 Zn=3:1:2. and the oxide semiconductor film 209 are each calculated by adding the sputtering time as an error. The atomic ratio of the metal elements contained in the target varies by ±40%. When the content of In contained in the compound semiconductor film 208 is large, the on-current of the transistor increases. Therefore, the oxide semiconductor film 208 is preferably formed by increasing the atomic number of the metal element. A sputtering target of In-M-Zn oxide with a ratio of In:M:Zn=3:1:2 was used. By forming the transistor using the above-mentioned compound, a transistor with excellent electrical characteristics can be manufactured.

[0117] As the oxide semiconductor film 208, an oxide semiconductor film with low carrier density is used. For example, The oxide semiconductor film 208 has a carrier density of 1×10 17 pieces / cm 3 Below, preferably 1x 10 15 pieces / cm 3 or less, more preferably 1 × 10 13 pieces / cm 3 The following is more preferable: is 1 x 10 11 pieces / cm 3 The following oxide semiconductor film is used.

[0118] In addition, the semiconductor characteristics and electrical characteristics (field effect) of the required transistors are not limited to these. It is sufficient to use an appropriate composition depending on the required properties (mobility, threshold voltage, etc.). In order to obtain semiconductor characteristics of a transistor, the carrier density and impurities of the oxide semiconductor film 208 are By appropriately adjusting the concentration, defect density, atomic ratio of metal elements to oxygen, interatomic distance, density, etc. It is preferable that:

[0119] Note that the oxide semiconductor film 208 is formed of an oxide semiconductor having a low impurity concentration and a low density of defect states. By using a thin film, it is possible to fabricate transistors with even better electrical properties. Here, it is preferable that the impurity concentration is low and the defect level density is low (there is little oxygen vacancy). High purity authentic or substantially high purity is called "high purity authentic" or "substantially high purity authentic". Since the oxide semiconductor is highly intrinsic, there are few carrier generation sources, and therefore it is possible to reduce the carrier density. Therefore, when a transistor in which a channel region is formed in the oxide semiconductor film is used, The transistor has electrical characteristics in which the threshold voltage is negative (also called normally on). In addition, oxide semiconductors that are high-purity intrinsic or substantially high-purity intrinsic may be Since the defect level density of the thin film is low, the trap level density may also be low.

[0120] In addition, the semiconductor film in which the channel is formed is provided with a high-purity intrinsic or substantially high-purity intrinsic acid. Transistors using nitride semiconductor films have extremely low off-state current and a channel width of 1×10 6 Even if the transistor has a channel length L of 10 μm, the source and drain electrodes When the voltage between the gate and drain (drain voltage) is in the range of 1V to 10V, the off-state current is below the measurement limit of the data analyzer, i.e., 1×10 -13 A characteristic of A or less can be obtained. Therefore, a transistor in which a channel region is formed in the oxide semiconductor film can be electrically The transistor may have little fluctuation in characteristics and high reliability. The charges trapped in the trap levels of the film take a long time to disappear, and they appear as if they are fixed. Therefore, in an oxide semiconductor film with a high density of trap states, The electrical characteristics of a transistor in which a channel region is formed may become unstable. Examples of the oxygen include hydrogen, nitrogen, an alkali metal, or an alkaline earth metal.

[0121] The hydrogen contained in the oxide semiconductor film reacts with the oxygen that is bonded to the metal atoms to form water, and the hydrogen Oxygen vacancies are formed in the lattice where oxygen has been desorbed (or in the part where oxygen has been desorbed). When hydrogen enters, electrons, which act as carriers, may be generated. By bonding with oxygen, which bonds with a metal atom, electrons that act as carriers may be generated. Therefore, a transistor using an oxide semiconductor containing hydrogen has normally-on characteristics. Easy to use.

[0122] Therefore, it is preferable that the amount of hydrogen in the oxide semiconductor film 208 be reduced as much as possible. Specifically, the oxide semiconductor film 208 is analyzed by secondary ion mass spectrometry (SIMS). The hydrogen concentration obtained by ion mass spectrometry (NMS) was , 2 × 10 20 atoms / cm 3 Less than or equal to 5 x 10 19 atoms / cm 3 Below or less, more preferably 1 x 10 19 atoms / cm 3 Below, 5 x 10 18 atoms / c m 3 Less than 1 × 10 18 atoms / cm 3 Less than or equal to 5 × 10 1 7 atoms / cm 3 or less, more preferably 1 × 10 16 atoms / cm 3 The following do.

[0123] When the oxide semiconductor film 208 contains silicon or carbon, which is one of the Group 14 elements, As a result, oxygen vacancies increase in the oxide semiconductor film 208, causing it to become n-type. The concentration of silicon and carbon in the semiconductor film 208 (obtained by secondary ion mass spectrometry) concentration) to 2 x 10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0124] In addition, in the oxide semiconductor film 208, alkali metal oxide was obtained by secondary ion mass spectrometry. The concentration of alkaline earth metals is 1×10 18 atoms / cm 3 Below, preferably 2×10 16 atoms / cm 3 Alkali metals and alkaline earth metals are When bonded to a carbide semiconductor, carriers may be generated, increasing the off-state current of the transistor. For this reason, the alkali metal or alkali metal in the oxide semiconductor film 208 may It is preferable to reduce the concentration of earth metals.

[0125] When nitrogen is contained in the oxide semiconductor film 208, electrons serving as carriers are generated. As a result, the nitride semiconductor containing nitrogen is used. Therefore, the transistor having the oxide semiconductor film tends to be normally on. Therefore, it is preferable that nitrogen is reduced as much as possible. For example, in secondary ion mass spectrometry, The resulting nitrogen concentration is 5 x 10 18 atoms / cm 3 It is preferable to do the following:

[0126] The structure of the oxide semiconductor film will be described below.

[0127] Oxide semiconductor films are roughly classified into non-single-crystal oxide semiconductor films and single-crystal oxide semiconductor films. The single-crystal oxide semiconductor film is called CAAC-OS (C Axis Aligned Crystal Polycrystalline oxide semiconductor film The oxide semiconductor film includes a microcrystalline oxide semiconductor film, an amorphous oxide semiconductor film, and the like.

[0128] First, the CAAC-OS film will be described.

[0129] The CAAC-OS film is one of oxide semiconductor films having a plurality of crystal parts aligned along the c-axis.

[0130] The CAAC-OS film was observed under a transmission electron microscope (TEM). When observed under a crystalline microscope, clear boundaries between the crystals, i.e., crystal boundaries, are clearly visible. It is not possible to confirm the grain boundary. It can be said that the AC-OS film is less susceptible to the decrease in electron mobility caused by grain boundaries.

[0131] The CAAC-OS film was observed by TEM from a direction roughly parallel to the sample surface (cross-sectional TEM observation). ) It can be confirmed that the metal atoms are arranged in layers in the crystalline part. Each layer has a surface on which the CAAC-OS film is formed (also referred to as a surface on which the CAAC-OS film is formed) or an uneven surface on which the CAAC-OS film is formed. The shape reflects this and is aligned parallel to the surface on which the CAAC-OS film is formed or the top surface.

[0132] On the other hand, the CAAC-OS film was observed by TEM from a direction approximately perpendicular to the sample surface (planar TEM). When observed, it was found that the metal atoms were arranged in triangular or hexagonal shapes in the crystals. However, there is no regularity in the arrangement of metal atoms between different crystal parts. stomach.

[0133] When electron diffraction was performed on the CAAC-OS film, spots (bright spots) indicating orientation were observed. Observed.

[0134] Cross-sectional and planar TEM observations revealed that the crystals in the CAAC-OS film had an orientation. It turns out that there are.

[0135] Most of the crystals in the CAAC-OS film are cubes with sides of less than 100 nm. Therefore, the crystal part included in the CAAC-OS film has a side length of 10n This also includes cases where the size fits within a cube of less than 100 mm, less than 5 nm, or less than 3 nm. In addition, multiple crystals in the CAAC-OS film are connected to form a single large crystal region. For example, in a planar TEM image, 2 Over 5μm 2 More than or equal to 1000 μm 2 Crystal regions with more than this size may be observed.

[0136] X-ray diffraction (XRD) was performed on the CAAC-OS film. For example, a CAAC-OS film with InGaZnO4 crystals was found by structural analysis using the device. In the out-of-plane analysis, a peak was observed at a diffraction angle (2θ) of approximately 31°. This peak is attributed to the (009) plane of the InGaZnO4 crystal. This indicates that the crystals of the CAAC-OS film have a c-axis orientation, and the c-axis is approximately aligned on the surface on which the film is formed or on the upper surface. It can be seen that it is oriented in a substantially vertical direction.

[0137] On the other hand, in-pl X-rays are incident on the CAAC-OS film from a direction approximately perpendicular to the c-axis. In the analysis by the ane method, a peak may appear at 2θ around 56°. This is attributed to the (110) plane of the InGaZnO4 crystal. In the case of a semiconductor film, 2θ is fixed at around 56°, and the normal vector of the sample surface is set as the axis (φ axis). When the sample is rotated and analyzed (φ scan), the crystal plane equivalent to the (110) plane is In contrast, in the case of the CAAC-OS film, 2θ is set to 5 Even when the φ is fixed at around 6° and scanned, no clear peak appears.

[0138] From the above, it is concluded that the a-axis and b-axis orientations are inconsistent between different crystal regions in the CAAC-OS film. Although it is regular, it has a c-axis orientation, and the c-axis is parallel to the normal vector of the surface to be formed or the upper surface. Therefore, the layered arrangement confirmed by the cross-sectional TEM observation mentioned above is consistent with the above. Each layer of aligned metal atoms is a plane parallel to the ab plane of the crystal.

[0139] The crystalline part is formed when the CAAC-OS film is formed or when a crystallization process such as a heat treatment is performed. As described above, the c-axis of the crystal is aligned with the surface on which the CAAC-OS film is formed or the surface on which the CAAC-OS film is formed. The orientation of the CAAC-OS film is parallel to the normal vector of the top surface. When the shape is changed by etching, the c-axis of the crystal is aligned with the surface on which the CAAC-OS film is formed. Or it may not be parallel to the normal vector of the upper surface.

[0140] Furthermore, the distribution of c-axis oriented crystal parts in the CAAC-OS film does not need to be uniform. For example, the crystalline part of the CAAC-OS film is formed by crystal growth from the vicinity of the top surface of the CAAC-OS film. When the crystal is formed by this method, the region near the top surface has a larger amount of c-axis oriented crystals than the region near the surface on which the crystal is formed. In addition, when impurities are added to the CAAC-OS film, the proportion of impurities may increase. The region where the ZnO was added was transformed, and regions with different proportions of c-axis oriented crystals were formed. This may also occur.

[0141] In addition, the out-of-plane method of CAAC-OS film with InGaZnO4 crystals In the analysis by , in addition to the peak at 2θ around 31°, a peak also appeared at 2θ around 36°. The peak at 2θ around 36° is due to the presence of c-axis orientation in part of the CAAC-OS film. The CAAC-OS film contains crystals that do not have a 2θ of around 31°. It is preferable that the peak is exhibited and that the peak is not exhibited at 2θ in the vicinity of 36°.

[0142] The CAAC-OS film is an oxide semiconductor film with a low concentration of impurities. These are elements other than the main components of the oxide semiconductor film, such as silicon and transition metal elements. The elements that bond to oxygen more strongly than the metal elements that constitute the oxide semiconductor film, such as fluorine, are oxidized. By removing oxygen from the oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disrupted, reducing its crystallinity. In addition, heavy metals such as iron and nickel, argon, and carbon dioxide have an atomic radius (or molecular radius) is large, and when it is contained inside the oxide semiconductor film, The impurities contained in the oxide semiconductor film are likely to disturb the atomic arrangement and cause a decrease in crystallinity. Objects can act as carrier traps or carrier sources.

[0143] The CAAC-OS film is an oxide semiconductor film with a low density of defect states. Oxygen vacancies in the semiconductor film can become carrier traps or trap hydrogen, It can be a source of carrier generation.

[0144] Low impurity concentration and low defect level density (low oxygen vacancies) are called high purity intrinsic or The term "substantially highly purified intrinsic" refers to a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film. Since there are fewer carrier generation sources, the carrier density can be reduced. A transistor using an oxide semiconductor film has electrical characteristics such as a negative threshold voltage ( It is also called marion.) It is rare for it to become high purity genuine or substantially high purity genuine. The oxide semiconductor film has few carrier traps. A transistor using such a material has little fluctuation in electrical characteristics and is highly reliable. Note that it takes a long time for charges trapped in the carrier traps in the oxide semiconductor film to be released. The time between the charges is long and the charge may behave as if it is a fixed charge. However, a transistor using an oxide semiconductor film with a high density of defect states has unstable electrical characteristics. There are cases where this happens.

[0145] In addition, transistors using CAAC-OS films show improved electrical characteristics when irradiated with visible light or ultraviolet light. The fluctuation is small.

[0146] Next, the polycrystalline oxide semiconductor film will be described.

[0147] In the polycrystalline oxide semiconductor film, crystal grains can be confirmed in the TEM observation image. The crystal grains contained in the crystalline oxide semiconductor film are, for example, 2 nm or more and 30 nm or less in a TEM observation image. The particle size is 0 nm or less, 3 nm to 100 nm or 5 nm to 50 nm In addition, the grain boundaries of polycrystalline oxide semiconductor films can be confirmed in TEM images. There are cases where this happens.

[0148] The polycrystalline oxide semiconductor film has a plurality of crystal grains, and the crystal orientation between the plurality of crystal grains is In addition, the structure of the polycrystalline oxide semiconductor film is measured using an XRD device. When structural analysis is performed, for example, the out of polycrystalline oxide semiconductor film having InGaZnO4 crystals In the analysis by the -of-plane method, a peak at 2θ near 31° and a peak at 2θ near 36° were observed. peak, or other peaks may appear.

[0149] A polycrystalline oxide semiconductor film has high crystallinity and therefore may have high electron mobility. Therefore, a transistor using a polycrystalline oxide semiconductor film has high field-effect mobility. However, impurities may segregate at the grain boundaries in a polycrystalline oxide semiconductor film. The grain boundaries of a crystalline oxide semiconductor film become defect states. Since a polycrystalline oxide semiconductor film may become a carrier trap or a carrier generation source, The transistors using this film have smaller fluctuations in electrical characteristics than transistors using a CAAC-OS film. This can result in large, unreliable transistors.

[0150] Next, a microcrystalline oxide semiconductor film will be described.

[0151] In the microcrystalline oxide semiconductor film, crystal parts can be clearly seen in the TEM image. The crystal part contained in the microcrystalline oxide semiconductor film may have a size of 1 nm or more and 100 nm or less. , or 1 nm to 10 nm in size. Nanocrystals (nc) are microcrystals of 1 nm or less and 3 nm or less. The oxide semiconductor film having nc-OS (nanocrystalline Oxide Semiconductor Film) The nc-OS film is called a TE film. In the M observation image, the grain boundaries may not be clearly visible.

[0152] The nc-OS film is a microscopic region (e.g., a region of 1 nm to 10 nm, especially a region of 1 nm or more). The nc-OS film has a periodic atomic arrangement in the region of 3 nm or less. There is no regularity in the crystal orientation between the crystal parts. Therefore, no orientation is observed throughout the film. Therefore, depending on the analytical method, the nc-OS film may be indistinguishable from an amorphous oxide semiconductor film. For example, an XRD apparatus using X-rays with a diameter larger than that of the crystals is used for nc-OS films. When structural analysis is performed using the out-of-plane method, the crystal plane is shown. In addition, the probe diameter ( Electron beam diffraction (also called selected area electron beam diffraction) using an electron beam of, for example, 50 nm or more When the diffraction pattern is changed to 0.05μm, a halo-like diffraction pattern is observed. The probe diameter is close to or smaller than the size of the crystal part (for example, 1 nm to 30 nm). When electron beam diffraction (also called nanobeam electron diffraction) is performed using an electron beam of Furthermore, when nanobeam electron diffraction is performed on the nc-OS film, a circular pattern is observed. In addition, a bright area (ring-shaped) may be observed in the nc-OS film. When performing electron beam diffraction, multiple spots may be observed within the ring-shaped region. do.

[0153] The nc-OS film is an oxide semiconductor film with higher order than an amorphous oxide semiconductor film. Therefore, the nc-OS film has a lower density of defect states than the amorphous oxide semiconductor film. In the nc-OS film, there is no regularity in the crystal orientation between different crystal parts. The S film has a higher defect state density than the CAAC-OS film.

[0154] Therefore, the nc-OS film may have a higher carrier density than the CAAC-OS film. An oxide semiconductor film with high carrier density may have high electron mobility. A transistor using an nc-OS film can have high field-effect mobility. The nc-OS film has a higher defect density than the CAAC-OS film, which leads to carrier tracking. Therefore, the transistor using the nc-OS film is Compared to transistors using S film, the electrical characteristics fluctuate greatly and the reliability is low. However, the nc-OS film can be formed even if it contains a relatively large amount of impurities. Therefore, it is easier to form than the CAAC-OS film, and it can be used preferably depending on the application. Therefore, it is possible to develop a semiconductor device having a transistor using an nc-OS film. The device may be manufactured with high productivity.

[0155] Next, the amorphous oxide semiconductor film will be described.

[0156] The amorphous oxide semiconductor film has an irregular atomic arrangement in the film and is an oxide film that does not have a crystalline portion. An example is an oxide semiconductor film that has an amorphous state, such as quartz.

[0157] In the amorphous oxide semiconductor film, no crystalline portion can be confirmed in the TEM observation image.

[0158] When the structure of the amorphous oxide semiconductor film is analyzed using an XRD device, out-of-p In the analysis by the Lane method, no peaks indicating crystal planes were detected. When electron diffraction is performed on a conductive film, a halo pattern is observed. When nanobeam electron diffraction is performed on a semiconductor film, no spots are observed, and a halo pattern is observed. is observed.

[0159] The amorphous oxide semiconductor film is an oxide semiconductor film containing impurities such as hydrogen at a high concentration. In addition, the amorphous oxide semiconductor film has a high density of defect states.

[0160] An oxide semiconductor film with a high impurity concentration and a high density of defect states has carrier traps and carrier The most common source of this is the oxide semiconductor film.

[0161] Therefore, the amorphous oxide semiconductor film has a higher carrier density than the nc-OS film. Therefore, a transistor using an amorphous oxide semiconductor film has a normally-on Therefore, it is difficult to obtain normally-on electrical characteristics from transistors that require normally-on electrical characteristics. The amorphous oxide semiconductor film has a high density of defect states. Therefore, the number of carrier traps may increase. The transistors using this film have a higher current density than transistors using CAAC-OS films or nc-OS films. The electrical characteristics fluctuate greatly, resulting in a transistor with low reliability.

[0162] Next, a single crystal oxide semiconductor film will be described.

[0163] A single-crystal oxide semiconductor film has a low impurity concentration and a low density of defect states (few oxygen vacancies). Therefore, the carrier density can be reduced. A transistor using a crystalline oxide semiconductor film rarely has normally-on electrical characteristics. In addition, since the single-crystal oxide semiconductor film has a low impurity concentration and a low density of defect states, Therefore, the rear trap may be reduced. The resulting transistor has little fluctuation in electrical characteristics and is highly reliable.

[0164] Note that the oxide semiconductor film has a high density when it has few defects. High crystallinity increases density. In addition, when the concentration of impurities such as hydrogen is low, the oxide semiconductor film The density of the single-crystal oxide semiconductor film is higher than that of the CAAC-OS film. The CAAC-OS film has a higher density than the microcrystalline oxide semiconductor film. The amorphous oxide semiconductor film has a higher density than the microcrystalline oxide semiconductor film. The density is higher than that of the porous oxide semiconductor film.

[0165] The oxide semiconductor film may be, for example, an amorphous oxide semiconductor film, a microcrystalline oxide semiconductor film, or a CA The AC-OS film may be a laminated film having two or more kinds of films.

[0166] The method for forming the oxide semiconductor film 208 and the oxide semiconductor film 209 will be described below. On the gate insulating film 207, an oxide semiconductor film 208 and an oxide semiconductor film 209 are formed. Next, a resist is formed on the oxide semiconductor film by a photolithography process. After forming a resist mask, part of the oxide semiconductor film is etched using the resist mask. In this way, the oxide semiconductor film 208 and the oxide semiconductor film 209 can be formed.

[0167] Oxide semiconductor films can be formed by sputtering, coating, pulsed laser deposition, and laser ablation. It can be formed by the sputtering method, CVD method, etc. When forming a semiconductor film, the power supply for generating plasma is an RF power supply, an A A C power supply, a DC power supply, etc. can be used as appropriate.

[0168] The sputtering gas may be a rare gas (typically argon) atmosphere, an oxygen atmosphere, a rare gas and In the case of a mixed gas of rare gas and oxygen, the ratio of rare gas to oxygen is It is preferable to increase the gas ratio of oxygen.

[0169] The sputtering target is appropriately selected depending on the composition of the oxide semiconductor film to be formed. You just need to choose.

[0170] In order to obtain a highly pure intrinsic or substantially highly pure intrinsic oxide semiconductor film, a chamber Not only is it necessary to evacuate the inside of the chamber to a high vacuum, but it is also necessary to highly purify the sputtering gas. The oxygen gas and argon gas used in this process have a dew point of -40°C or less, preferably -80°C or less, and Preferably, the gas is purified to a temperature of -100°C or lower, more preferably -120°C or lower. By using the oxide semiconductor film, it is possible to prevent moisture and the like from being taken into the oxide semiconductor film as much as possible. .

[0171] Here, the oxide semiconductor film is an In-Ga film with an atomic ratio of In:Ga:Zn=1:1:1. A 35 nm thick In-Ga was deposited by sputtering using a Zn oxide target. Next, a resist mask is formed on the oxide semiconductor film, and the oxide semiconductor film is By selectively etching a part of the oxide semiconductor film, the oxide semiconductor film 208 and the oxide A compound semiconductor film 209 can be formed.

[0172] After that, first heat treatment may be performed. Hydrogen, water, and the like contained in the oxide semiconductor film 208 and the oxide semiconductor film 209 are released. The hydrogen concentration and the water concentration in the oxide semiconductor film 8 and the oxide semiconductor film 209 can be reduced. The temperature of the heat treatment is typically 300° C. or higher and 400° C. or lower, preferably 320° C. or higher. The temperature must be below 370°C.

[0173] The first heat treatment can be carried out using an electric furnace, an RTA device, or the like. By doing so, it is possible to perform heat treatment at a temperature above the distortion point of the substrate for a short period of time. Therefore, the heat treatment time can be shortened.

[0174] The first heat treatment is carried out in an atmosphere of nitrogen, oxygen, or ultra-dry air (with a water content of 20 ppm or less, preferably air at 1 ppm or less, preferably 10 ppb or less), or rare gases (argon, helium The above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas may be added to hydrogen. It is preferable that the mixture does not contain water or the like. After the heat treatment in a nitrogen or rare gas atmosphere, Heating may be performed in an oxygen or ultra-dry air atmosphere. As a result, the oxide semiconductor film 208 and Hydrogen, water, and the like contained in the oxide semiconductor film 209 are released, and the oxide semiconductor film 20 Oxygen can be supplied to the oxide semiconductor film 8 and the oxide semiconductor film 209. The amount of oxygen vacancies in the oxide semiconductor film 208 and the oxide semiconductor film 209 can be reduced. .

[0175] Note that an example in which the oxide semiconductor film 209 is formed as one electrode of the capacitor 232 is shown. However, one aspect of the embodiment of the present invention is not limited to this. Depending on the situation, a non-light-transmitting conductive film may be used as one electrode of the capacitor 232. Alternatively, a film formed in a different process from the oxide semiconductor film 208 may be used. That is, it may be provided in a location that does not come into contact with the upper surface of the gate insulating film 207.

[0176] [Forming the source electrode and drain electrode] Next, the source electrode 209a, the drain electrode 209b, and the electrode 210 are formed. , a conductive film 220 is formed over the insulating film 205, the oxide semiconductor film 208, and the oxide semiconductor film 209. (See FIG. 4(C)).

[0177] The conductive film 220 may be made of aluminum, titanium, chromium, nickel, copper, yttrium, elemental metals consisting of zirconium, molybdenum, silver, tantalum, or tungsten, or The alloy containing this as the main component can be used in a single layer structure or a laminated structure. A single-layer structure of aluminum film containing silicon, and a two-layer structure of aluminum film laminated on titanium film Two-layer structure with aluminum film laminated on tungsten film, copper-magnesium-aluminum Two-layer structure with copper film laminated on aluminum alloy film, two-layer structure with copper film laminated on titanium film, Two-layer structure in which a copper film is laminated on a titanium film or titanium nitride film and the titanium film Alternatively, an aluminum film or copper film is laminated on the titanium nitride film, and then a titanium film is further laminated on top of that. a three-layer structure forming a titanium nitride film or a molybdenum nitride film, a molybdenum film or a molybdenum nitride film, An aluminum film or a copper film is laminated on the molybdenum film or the molybdenum nitride film. a three-layer structure in which a molybdenum film or a molybdenum nitride film is formed on top of the tungsten film; For example, a three-layer structure is used in which a copper film is laminated on a silicon film, and a tungsten film is further formed on top of that.

[0178] In addition, indium tin oxide, zinc oxide, indium oxide containing tungsten oxide, acid Indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, Indium tin oxide containing titanium, indium zinc oxide, indium with silicon oxide Conductive materials containing oxygen, such as aluminum tin oxide, and those containing nitrogen, such as titanium nitride and tantalum nitride. A conductive material may be used. In addition, a material containing the above-mentioned metal element and a conductive material containing oxygen may be used. It is also possible to use a laminated structure in which the above-mentioned material containing a metal element and It is also possible to use a laminated structure in which a conductive material containing nitrogen is combined. A product of a combination of a material containing an element, a conductive material containing oxygen, and a conductive material containing nitrogen It can also be a layered structure.

[0179] The thickness of the conductive film 220 is 5 nm or more and 500 nm or less, and more preferably 10 nm or more. The thickness is 300 nm or less, and more preferably 10 nm or more and 200 nm or less. A tungsten film having a thickness of 300 nm is formed as the conductive film 220 .

[0180] Subsequently, a resist mask is formed on the conductive film 220 by a photolithography process. By selectively etching a part of the conductive film 220 using a mask, the source electrode 20 9a, the drain electrode 209b, and the electrode 210 are formed. In addition, the terminal electrode 116, etc. Other electrodes and wiring can also be formed at the same time.

[0181] The conductive film 220 may be etched by either dry etching or wet etching. Note that the exposed part of the oxide semiconductor film is removed by the etching step. In some cases, the data may be removed (see FIG. 5(A)).

[0182] [Forming an oxide insulating film] Next, the insulating film 108 is formed. The insulating film 108 is an oxide insulating film that is permeable to oxygen. The insulating film 108 is formed by removing the oxide semiconductor film 20 when the insulating film 109 is formed later. It also functions as a film to mitigate damage to 8 (see Figure 5(B)).

[0183] The insulating film 108 has a thickness of 5 nm to 150 nm, preferably 5 nm to 50 nm. Silicon oxide, silicon oxynitride, etc. having a thickness of 1 m or less can be used. In this context, an oxynitride film refers to a film whose composition contains more oxygen than nitrogen, and The oxide film is a film whose composition contains more nitrogen than oxygen.

[0184] Furthermore, it is preferable that the insulating film 108 has a small number of defects. The density of spins with g=2.001 originating from the silicon dangling bonds is 3×10 17 spins / cm 3 This is because the insulating film 108 contains If the density of defects contained in the insulating film 108 is high, oxygen will bond to the defects, and the oxygen in the insulating film 108 will This is because the amount of light transmitted through the glass decreases.

[0185] In addition, it is preferable that the number of defects at the interface between the insulating film 108 and the oxide semiconductor film 208 is small. Typically, ESR measurement reveals that the oxide semiconductor film 208 has a defect density of g=1. The spin density of the signal appearing at 93 is 1×10 17 spins / cm 3 Below, and further under detection It is preferable that the temperature is below the limit.

[0186] In the insulating film 108, all of the oxygen that has entered the insulating film 108 from the outside is Some oxygen does not move to the outside and remains in the insulating film 108. At the same time, oxygen contained in the insulating film 108 moves to the outside of the insulating film 108, Oxygen transfer may also occur at 108.

[0187] When an oxide insulating film that transmits oxygen is formed as the insulating film 108, The oxygen released from the insulating film 109 is transferred to the oxide semiconductor film 208 through the insulating film 108. It can be moved.

[0188] The insulating film 108 is preferably a silicon oxide film or a silicon oxynitride film. The silicon oxide film or silicon oxynitride film used for the insulating film 108 is, for example, a plasma The substrate placed in the vacuum-evacuated processing chamber of the CVD equipment is heated to a temperature between 280°C and 400°C. The pressure in the processing chamber is maintained at 20 Pa or more and 250 Pa or less by introducing a raw material gas into the processing chamber. The pressure is preferably 100 Pa or more and 250 Pa or less, and the pressure is applied to an electrode provided in the processing chamber. It can be formed by adjusting the conditions under which high frequency power is supplied.

[0189] Silicon is used as a source gas for forming a silicon oxide film or a silicon oxynitride film. It is preferable to use a deposition gas containing silicon and an oxidizing gas. Examples include silane, disilane, trisilane, and fluorinated silane. Examples include oxygen, ozone, nitrous oxide, and nitrogen dioxide.

[0190] By using the above conditions, an oxide insulating film that transmits oxygen can be formed as the insulating film 108. Furthermore, by providing the insulating film 108, the oxidation in the process of forming the insulating film 109 can be prevented. This makes it possible to reduce damage to the compound semiconductor film 208.

[0191] Furthermore, under the film formation conditions, by setting the substrate temperature to the above temperature, the bond between silicon and oxygen As a result, the insulating film 108 becomes oxygen-permeable, dense, and hard. Oxide insulating film, typically etched using 0.5 wt % hydrofluoric acid at 25°C A silicon oxide film or an oxide film having a grading rate of 10 nm / min or less, preferably 8 nm / min or less. A silicon nitride film can be formed.

[0192] In addition, by forming the insulating film 108 while heating, the oxide semiconductor film Hydrogen, water, and the like contained in the oxide semiconductor film 208 and the oxide semiconductor film 209 can be released. Specifically, the insulating film 108 is heated while the element formation substrate 101 is maintained at a temperature of 280° C. or higher and 400° C. or lower. By forming the oxide semiconductor film 208, hydrogen, water, and the like contained in the oxide semiconductor film 208 can be released. The hydrogen contained in the oxide semiconductor film 208 is bonded to the oxygen radicals generated in the plasma. Since the substrate is heated in the process of forming the insulating film 108, oxygen and water The water generated by the bond of the elements is released from the oxide semiconductor film. By forming the insulating film 108 in this manner, the contents of water and hydrogen contained in the oxide semiconductor film can be reduced. can be reduced.

[0193] In addition, since heating is performed in the step of forming the insulating film 108, the oxide semiconductor film 208 and The heating time in the exposed state of the oxide semiconductor film 209 is short, and the oxide semiconductor film 209 is The amount of oxygen released from the conductive film can be reduced. The amount of oxygen deficiency can be reduced.

[0194] Furthermore, by setting the pressure in the processing chamber to 100 Pa or more and 250 Pa or less, the insulating film 108 The reduced water content reduces the variation in the electrical characteristics of transistors. In both cases, the fluctuation of the threshold voltage can be suppressed.

[0195] In addition, the pressure in the processing chamber is set to 100 Pa or more and 250 Pa or less, so that the insulating film 108 is formed. In this case, damage to the oxide semiconductor film 208 and the oxide semiconductor film 209 can be reduced. The oxide semiconductor film 208 and the oxide semiconductor film 209 can be formed by oxygen vacancies. In particular, the amount of the insulating film 108 or the insulating film 109 to be formed later can be reduced. By increasing the film temperature, typically to a temperature higher than 220° C., the oxide semiconductor film 20 Part of oxygen contained in the oxide semiconductor film 8 and the oxide semiconductor film 209 is released, and oxygen vacancies are easily formed. stomach.

[0196] In order to improve the reliability of the transistor, the insulating film 109 to be formed later is formed by reducing the number of defects in the film. When the insulating film 109 is formed under film formation conditions with less oxygen desorption, the amount of oxygen desorbed from the insulating film 109 is likely to be reduced. Then, oxygen is supplied from the insulating film 109, and the oxide semiconductor film 208 and the oxide semiconductor film 209 are It may be difficult to compensate for the oxygen deficiency in the conductive film 209. The pressure is set to 100 Pa or more and 250 Pa or less, and the oxide semiconductor during the formation of the insulating film 108 is By reducing damage to the insulating film 208 and the oxide semiconductor film 209, Even if the amount of oxygen supplied from the oxide semiconductor film 208 is small, the amount of oxygen in the oxide semiconductor film 209 is small. It is possible to reduce the element deficiency.

[0197] In addition, by increasing the amount of oxidizing gas to 100 times or more the amount of deposition gas containing silicon, It is possible to reduce the hydrogen content in the insulating film 108. As a result, the oxide semiconductor Since the amount of hydrogen mixed into the oxide semiconductor film 208 and the oxide semiconductor film 209 can be reduced, Therefore, the negative shift of the threshold voltage can be suppressed.

[0198] In this embodiment, the insulating film 108 is formed by a plasma process using silane and dinitrogen monoxide as raw material gases. A silicon oxynitride film with a thickness of 50 nm is formed by the Zuma CVD method. A silicon oxynitride film through which oxygen is transmitted can be formed.

[0199] Next, an insulating film 109 is formed in contact with the insulating film 108. The insulating film 109 has a stoichiometric composition The oxide insulating film is formed using an oxide insulating film containing more oxygen than the oxygen that satisfies the stoichiometric composition. When the oxide insulating film contains more oxygen than the oxygen to be filled, part of the oxygen is released by heating. The oxide insulating film containing more oxygen than the stoichiometric composition is analyzed by TDS. The amount of oxygen released in terms of oxygen atoms is 1.0 × 10 18 atoms / cm 3 That's all, I prefer 3.0 x 10 20 atoms / cm3 The oxide insulating film is the above-mentioned T The substrate temperature during DS analysis is 100°C or higher and 700°C or lower, or 100°C or higher and 500°C or lower. A range of 00°C or less is preferred.

[0200] After the insulating film 108 is formed, the insulating film 109 is successively formed without exposing the insulating film 108 to the air. After the insulating film 108 is formed, the flow rate, pressure, and other parameters of the source gas are preferably adjusted without exposing the insulating film 108 to the atmosphere. By adjusting one or more of the high frequency power and the substrate temperature, the insulating film 109 is continuously formed. To reduce the concentration of impurities originating from atmospheric components at the interface between the insulating film 108 and the insulating film 109. At the same time, oxygen contained in the insulating film 109 is transferred to the oxide semiconductor film 208 and the oxide semiconductor film 209. The oxide semiconductor film 208 and the oxide semiconductor film 209 can be moved to the oxide semiconductor film 208. The amount of oxygen vacancy in 209 can be reduced.

[0201] Furthermore, it is preferable that the insulating film 109 has a small number of defects. , the spin density of the signal appearing at g=2.001 due to the silicon dangling bond is 1.5×10 18 spins / cm 3 Less than or even 1×10 18 spins / cm 3 below Note that the insulating film 109 is preferably an oxide semiconductor film, as compared with the insulating film 108. Since it is far from the insulating film 208, it may have a higher defect density than the insulating film 108.

[0202] The insulating film 109 is preferably a silicon oxide film or a silicon oxynitride film. The silicon oxide film or silicon oxynitride film used for the insulating film 109 is, for example, a plasma The substrate placed in the evacuated processing chamber of the CVD device is heated to 180°C or higher and 280°C or lower. More preferably, the temperature is kept at 200° C. or higher and 240° C. or lower, and the raw material gas is introduced into the processing chamber. The pressure in the room is 100 Pa or more and 250 Pa or less, more preferably 100 Pa or more and 250 Pa or less. 00 Pa or less, and 0.17 W / cm 2 More than 0.5W / cm 2 or less, more preferably 0.25 W / cm 2 More than 0.35W / cm 2 High frequency power of can be formed by supplying

[0203] The thickness of the insulating film 109 is 30 nm or more and 500 nm or less, preferably 50 nm or more and 400 nm or less. m or less.

[0204] The conditions for forming the insulating film 109 are as follows: high frequency power of the above power density in a reaction chamber of the above pressure; By supplying the source gas, the decomposition efficiency in the plasma increases, oxygen radicals increase, As the oxidation of the source gas progresses, the oxygen content in the insulating film 109 becomes higher than the stoichiometric ratio. On the other hand, in the film formed at the above substrate temperature, the bonding strength between silicon and oxygen is weak. Therefore, a part of the oxygen in the film is released by the heat treatment in the subsequent process. An oxide insulating film that contains more oxygen than satisfies the composition and from which some of the oxygen is released by heating In addition, the insulating film 108 is provided over the oxide semiconductor film 208. Therefore, in the step of forming the insulating film 109, the insulating film 108 is formed on the oxide semiconductor film 208. As a result, damage to the oxide semiconductor film 208 can be reduced and power density can be increased. The insulating film 109 can be formed using high-intensity high-frequency power.

[0205] In the film formation conditions for the insulating film 109, the ratio of a deposition gas containing silicon to an oxidizing gas is By increasing the flow rate, it is possible to reduce the number of defects in the insulating film 109. appears at g=2.001 due to the dangling bond of silicon by ESR measurement. The spin density of the signal is 6×10 17 spins / cm 3 Less than 3 x 10 17 s pins / cm 3 Less than or equal to 1.5 × 10 17 spins / cm 3 Defects that are less than This allows the formation of a small amount of oxide insulating film, which improves the reliability of the transistor. It is possible.

[0206] In this embodiment, the insulating film 109 is formed by a plasma process using silane and dinitrogen monoxide as raw material gases. A silicon oxynitride film with a thickness of 400 nm is formed by the Zuma CVD method.

[0207] Next, a second heat treatment is performed. The temperature of the heat treatment is typically 150° C. or higher and 400° C. Preferably, the temperature is 300°C or higher and 400°C or lower, more preferably 320°C or higher and 370°C or lower. do.

[0208] The second heat treatment can be performed using an electric furnace, an RTA device, or the like. Therefore, the heat treatment can be performed at a temperature above the distortion point of the substrate for a short period of time. The heat treatment time can be shortened.

[0209] The second heat treatment is carried out in an atmosphere of nitrogen, oxygen, or ultra-dry air (with a water content of 20 ppm or less, preferably air at 1 ppm or less, preferably 10 ppb or less), or rare gases (argon, helium The above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas may be added to hydrogen. It is preferable that the solvent does not contain water.

[0210] By the second heat treatment, part of oxygen contained in the insulating film 109 is transferred to the oxide semiconductor film 208. By this, oxygen vacancies in the oxide semiconductor film 208 can be filled. As a result, the amount of oxygen vacancies in the oxide semiconductor film 208 can be further reduced.

[0211] When the insulating films 108 and 109 contain water, hydrogen, or the like, the insulating film 108 and the insulating film 109 may be formed by blocking the water, hydrogen, or the like. When the insulating film 110 having a function of bonding is formed later and heat treatment is performed, the insulating film 108 and Water, hydrogen, and the like contained in the insulating film 109 move to the oxide semiconductor film 208, and the oxide semiconductor film However, the heating causes defects in the insulating film 108 and the insulating film 208. It is possible to remove water, hydrogen, etc. contained in 109, and the electrical characteristics of the transistor can be improved. This reduces variations and suppresses fluctuations in threshold voltage.

[0212] Note that the insulating film 109 is formed over the insulating film 108 while heating, so that the oxide semiconductor film Oxygen can be transferred to the oxide semiconductor film 208 to fill oxygen vacancies in the oxide semiconductor film 208. Therefore, the second heat treatment does not need to be performed.

[0213] Here, heat treatment is performed in a mixed gas atmosphere of nitrogen and oxygen at 350° C. for 1 hour.

[0214] In addition, when forming the pair of source electrode 209a and drain electrode 209b, the conductive film 220 The oxide semiconductor film 208 is damaged by etching, and the oxide semiconductor film 208 The back channel (the surface of the oxide semiconductor film 208 opposite to the surface facing the gate electrode 206) However, the insulating film 109 contains more oxygen than the stoichiometric composition. By using an oxide insulating film containing more oxygen than the backchannel insulating film, the backchannel insulating film can be As a result, oxygen vacancies occurring on the panel side can be repaired. This reduces the number of defects contained in the transistor, thereby improving its reliability. Cut.

[0215] [Removing part of the oxide insulating film] Next, a mask is formed on the insulating film 109 by a photolithography process. Part of the insulating film 108 is selectively etched to form an opening on the oxide semiconductor film 209. At this time, other openings (not shown) are also formed (see FIG. 5(C)). The insulating film 109 and the insulating film 108 can be etched by dry etching or wet etching. Etching methods, or a combination of both methods, can be used.

[0216] After that, second heat treatment may be performed. Part of the oxygen is transferred to the oxide semiconductor film 208 and the oxide semiconductor film 209. It is possible to reduce oxygen vacancies in the semiconductor film 208 and the oxide semiconductor film 209. is.

[0217] [Forming a protective film] Next, the insulating film 110 is formed (see FIG. 6A). An insulating film having a blocking effect against water, alkali metals, alkaline earth metals, etc. is used. As a result, oxygen contained in the oxide semiconductor film 208, the insulating film 108, and the insulating film 109 is absorbed by the outside. In addition, hydrogen can be prevented from diffusing into the oxide semiconductor film 208 from the outside. It is possible to prevent the intrusion of impurities such as water. Such insulating films include silicon nitride films, silicon nitride oxide films, and aluminum nitride films. , aluminum oxide nitride film, aluminum oxide film, aluminum oxynitride film, gallium oxide gallium oxide film, yttrium oxide film, yttrium oxide nitride film, hafnium oxide film Examples of insulating films include hafnium oxide, hafnium nitride, and other nitride insulating films.

[0218] The structure of the insulating film 110 is not limited to the above structure, and may be an oxide insulating film or a nitride insulating film. It can be a single layer or a multi-layer laminate.

[0219] In this embodiment, a silicon nitride film containing hydrogen is formed as the insulating film 110.

[0220] The oxide semiconductor film 209 is in contact with the insulating film 110 in the opening 122. Hydrogen contained in the insulating film 110 diffuses into the oxide semiconductor film 209 through the openings 122, The oxygen atoms bond with oxygen in the oxide semiconductor film 209 to generate electrons as carriers. Furthermore, when the insulating film 110 is formed by plasma CVD or sputtering, the opening 1 In step 22, the oxide semiconductor film 209 is exposed to plasma, and oxygen deficiency is formed in the oxide semiconductor film 209. When hydrogen contained in the insulating film 110 enters the oxygen vacancies, As a result, the conductivity of the oxide semiconductor film 209 increases, and That is, the oxide semiconductor film 209 having conductivity is The conductive oxide semiconductor film 209 can be said to be a highly conductive oxide semiconductor film. can be said to be a highly conductive metal oxide film.

[0221] Note that before the insulating film 110 is formed, the oxide semiconductor film 209 is irradiated with plasma containing a rare gas and hydrogen. By exposing the oxide semiconductor film 209 to the ultraviolet light, oxygen vacancies are formed in the oxide semiconductor film 209. As a result, hydrogen can be added to the oxide semiconductor film 209. The oxide semiconductor film can further increase the number of electrons serving as carriers and has conductivity. The conductivity of 209 can be further increased.

[0222] The conductive oxide semiconductor film 209 contains the same metal element as the oxide semiconductor film 208. The film is characterized by containing impurities, such as hydrogen. Impurities other than hydrogen include boron, phosphorus, tin, antimony, rare gas elements, and aluminum. Potassium metal, alkaline earth metal, etc. may also be contained.

[0223] The oxide semiconductor film 208 and the conductive oxide semiconductor film 209 are both gate insulating films. The oxide semiconductor film 207 is formed on the oxide semiconductor film 208, but the impurity concentration is different. The impurity concentration of the conductive oxide semiconductor film 209 is higher than that of the oxide semiconductor film 208. The hydrogen concentration in the compound semiconductor film 208 is 5×10 19 atoms / cm 3 Less than, preferred Kuha 5 x 10 18 atoms / cm 3 Less than 1 x 10 18 atoms / cm 3 Less than or equal to 5 × 10 17 atoms / cm 3 or less, more preferably 1 × 10 16 atoms / cm 3The water contained in the conductive oxide semiconductor film 209 is The elementary concentration is 8 x 10 19 or more, preferably 1 × 10 20 atoms / cm 3 More than that, better Preferably 5 x 10 20 In addition, the oxide semiconductor film 204 has higher conductivity than the oxide semiconductor film 208. The hydrogen concentration in the oxide semiconductor film 209 is two times, preferably ten times or more, higher than that in the oxide semiconductor film 209.

[0224] In addition, the conductive oxide semiconductor film 209 has a lower resistivity than the oxide semiconductor film 208. The resistivity of the oxide semiconductor film 208 is higher than that of the oxide semiconductor film 209 having conductivity. 1×10 1 1×10 times more 8 It is preferable that the ratio is less than 1 / 2. The resistivity of the film 209 is typically 1×10 -3 Ωcm or more 1×10 4 Less than Ωcm, and Preferably, the resistivity is 1×10 -3 Ωcm or more 1×10 -1 It is preferable that the resistivity is less than Ωcm.

[0225] Note that one aspect of the embodiment of the present invention is not limited thereto, and a conductive oxide semiconductor film In some cases, the insulating film 209 may not be in contact with the insulating film 110.

[0226] Furthermore, one aspect of the embodiment of the present invention is not limited thereto, and may be a conductive oxide semiconductor film. The oxide semiconductor film 209 may be formed in a separate process from the oxide semiconductor film 208. In that case, The oxide semiconductor film 209 may be made of a different material from the oxide semiconductor film 208. For example, the conductive oxide semiconductor film 209 may be formed using indium tin oxide, tungsten oxide, or the like. Indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, titanium oxide Indium oxide containing titanium, indium tin oxide containing titanium oxide, indium tin oxide Indium zinc oxide, indium tin oxide containing silicon oxide, etc. Good too.

[0227] In the display device described in this embodiment, a semiconductor film of a transistor and a capacitor are formed simultaneously. In addition, a light-transmitting conductive film that functions as a pixel electrode is formed in addition to the capacitor element. Therefore, in order to form a capacitor element, a process for forming a conductive film is required. This eliminates the need for a process for manufacturing a semiconductor device, thereby reducing the number of steps required for manufacturing the semiconductor device. Since the electrodes have light-transmitting properties, the capacitor element also has light-transmitting properties. It is possible to increase the aperture ratio of the pixel while increasing the

[0228] Next, a part of the insulating film 110, the insulating film 109, and the insulating film 108 is selectively etched. The opening 142 is formed. At this time, other openings (not shown) are also formed at the same time. The openings 142 and the like are formed by forming a resist mask by a photolithography process. The area not covered by the mask can be etched away (Fig. 6(B)). )). At the bottom of the opening 142, the surface of the source electrode 209a is exposed.

[0229] The insulating film 110, the insulating film 109, and the insulating film 108 are etched by, for example, dry etching. However, the present invention is not limited to this, and other methods such as wet etching and Alternatively, a combination of dry etching and wet etching may be used.

[0230] [Forming a conductive film] Next, a conductive film for forming the conductive film 145 is formed on the insulating film 110 so as to cover the opening 122. A resist mask is formed over the conductive layer by a photolithography process. The area not covered by the photomask is etched to form a conductive film 145 (FIG. 7(A)). reference.).

[0231] At the same time as the formation of the conductive film 145, a gate electrode 206 and a film overlapping with the oxide semiconductor film 208 are formed. The conductive film 145 and the electrode 226 can be formed in the area where the gate electrode 226 is formed. It can be formed using the same materials and methods as the electrode 206 .

[0232] In addition, the conductive film 145 is formed using a light-transmitting conductive material, so that the capacitor 232 In this embodiment, the conductive film 145 and the The electrode 226 is made of indium tin oxide having a thickness of 100 nm (see FIG. 7A). .

[0233] The electrode 226 can also function as a gate electrode. When either electrode 6 or electrode 226 is simply referred to as a "gate electrode," the other is referred to as a "back gate." In addition, either the gate electrode 206 or the electrode 226 may be referred to as a "gate electrode." One may be referred to as the "first gate electrode" and the other as the "second gate electrode."

[0234] In general, the back gate electrode is formed of a conductive film, and the gate electrode and the back gate electrode form a semiconductor. The back gate electrode is disposed so as to sandwich the channel forming region of the layer. The back gate electrode can be made to function in the same manner as the gate electrode. The potential of the back gate electrode may be changed, or may be set to the GND potential or any other potential. By changing the voltage, the threshold voltage of the transistor can be changed.

[0235] In addition, since the gate electrode and back gate electrode are made of a conductive film, they can be easily The function of preventing the electric field generated from acting on the semiconductor layer where the channel is formed (especially static electricity It also has electrostatic shielding function against

[0236] In addition, when light is incident from the back gate electrode side, the back gate electrode is By forming the semiconductor layer from a conductive film, light is prevented from entering the semiconductor layer from the back gate electrode side. This prevents light degradation of the semiconductor layer and shifts the threshold voltage of the transistor. This can prevent deterioration of electrical characteristics such as

[0237] The gate electrode 206 and the electrode 226 are provided with the oxide semiconductor film 208 interposed therebetween, In this case, the gate electrode 206 and the electrode 226 are set to the same potential, so that the oxide semiconductor film 208 The area in which carriers flow is larger in the film thickness direction, so the amount of carrier movement is As a result, the on-state current of the transistor increases and the field-effect mobility increases. It becomes.

[0238] Furthermore, the gate electrode 206 and the electrode 226 each have the function of shielding an external electric field. Therefore, the charges present in the layer below the gate electrode 206 and the layer above the electrode 226 are This does not affect the oxide semiconductor film 208. As a result, a stress test (for example, applying a negative voltage to the gate) can be performed. Gate Bias-Temperature (GBT) stress test The change in threshold voltage before and after the GBT stress test (applying a positive voltage to the gate) Also, the fluctuation of the on-current rise voltage at different drain voltages is suppressed. This effect can be achieved when the gate electrode 206 and the electrode 226 are at the same potential. This can occur even at different potentials.

[0239] The BT stress test is a type of accelerated test that measures the transients that occur during long-term use. It is possible to evaluate the change in the characteristics of the BT string (i.e., the change over time) in a short time. The amount of change in the threshold voltage of a transistor before and after the load test is an important factor for examining reliability. The smaller the threshold voltage fluctuation before and after the BT stress test, the better the It can be said that this is a highly reliable transistor.

[0240] Also, the gate electrode 206 and the electrode 226 are included, and the gate electrode 206 and the electrode 22 By making the potentials of the transistors 6 the same, the amount of variation in the threshold voltage is reduced. At the same time, the variations in electrical characteristics of the transistors are reduced.

[0241] [Forming a planarizing film] Next, an insulating film 211 is formed over the conductive film 145. The insulating film 211 is formed in the same manner as the insulating film 205. The material and method can be used to form the above-mentioned.

[0242] In addition, in order to reduce the surface irregularities on the surface on which the light emitting element 125 is formed, the insulating film 211 is subjected to a planarization process. The planarization process is not particularly limited, but may be a polishing process (for example, a chemical mechanical polishing process). Polishing method (Chemical Mechanical Polishing: CMP), This can be done by dry etching or etching.

[0243] In addition, by forming the insulating film 211 using an insulating material having a planarizing function, the polishing process can be performed. The insulating material having a planarizing function may be, for example, a polyimide resin, Organic materials such as acrylic resins can be used. In addition to the above organic materials, low dielectric constant materials can also be used. In addition, insulating films formed from these materials can be used. The insulating film 211 may be formed by stacking a plurality of layers.

[0244] Also, a part of the insulating film 211 in the region overlapping the opening 142 is removed to form an opening 143. At this time, other openings (not shown) are also formed at the same time. The insulating film 211 in the region to be connected is also removed. A resist mask is formed by a photolithography process, and the resist mask of the insulating film 211 is The opening can be formed by etching the area not covered by the mask (see Figure 7(B)). By forming the portion 143, the surface of the source electrode 209a is exposed.

[0245] In addition, by using a photosensitive material for the insulating film 211, it is possible to avoid the need for a resist mask. In this embodiment, the opening 143 can be formed without using a photosensitive polyimide resin. The insulating film 211 and the opening 143 are formed using the method.

[0246] [Forming the anode] Next, an electrode 115 is formed on the insulating film 211 (see FIG. 8(A)). The EL layer 117 is formed using a conductive material that efficiently reflects the light emitted by the EL layer 117. It is preferable that the electrode 115 is not limited to a single layer, but may have a multi-layer structure. For example, when the electrode 115 is used as an anode, the layer in contact with the EL layer 117 is made of indium tin oxide. The layer has a work function larger than that of the EL layer 117 of the material and has light-transmitting properties, and the layer is in contact with the reflective layer. A layer with high refractive index (aluminum, an alloy containing aluminum, or silver, etc.) may be provided. .

[0247] In this embodiment, a display device having a top emission structure is exemplified. Bottom emission structure (bottom injection structure) or dual emission structure (double injection structure) ) display device.

[0248] The display device is available in bottom emission structure and dual emission structure. In the case of a display device having a (dual emission structure), a conductive material having light transmitting properties is used for the electrode 115. That's good enough.

[0249] The electrode 115 is formed by forming a conductive film to be the electrode 115 on the insulating film 211 and then forming the conductive film by photolithography. A resist mask is formed by a process, and the area of ​​the conductive film that is not covered with the resist mask is The conductive film can be formed by etching the conductive film. A wet etching method or a combination of both methods can be used.

[0250] [Forming a partition] Next, the partition wall 114 is formed. The partition wall 114 prevents the adjacent light emitting elements 125 from being accidentally electrically This prevents the EL layer 117 from being short-circuited and erroneously emitting light. When a metal mask is used, it also has the function of preventing the metal mask from coming into contact with the electrode 115. The partition wall 114 is made of an organic resin material such as epoxy resin, acrylic resin, or imide resin, or an acid The partition wall 114 can be formed of an inorganic material such as silicon dioxide. Alternatively, it is preferable to form the inclined surface with a continuous curvature. By forming the sidewalls of the wall 114 in this shape, the EL layer 117 and the electrode 11 formed later can be easily formed. The coating property of 8 can be improved.

[0251] [Forming the EL layer] The configuration of the EL layer 117 will be described in the seventh embodiment.

[0252] [Forming the cathode] In this embodiment, the electrode 118 is used as a cathode, and therefore the electrode 118 is connected to the EL layer 11 (described later). It is preferable to form the electrode 7 using a material with a small work function that can inject electrons. Instead of a metal with a low work function, an alkali metal or alkaline earth metal with a low work function is used. A layer of metal formed several nanometers is formed as a buffer layer, and then a metal material such as aluminum is formed on top of it. The insulating film is formed using a conductive oxide material such as indium tin oxide or a semiconductor material. The buffer layer may be made of an oxide, halide, or magnesium of an alkaline earth metal. An alloy such as neodymium-silver can also be used.

[0253] In addition, when light emitted from the EL layer 117 is extracted through the electrode 118, the electrode 118 is The electrode 115, the EL layer 117, and the electrode 118 preferably have a property of transmitting visible light. Thus, the light emitting element 125 is formed.

[0254] [Forming the opposing substrate] The substrate 121 ( Hereinafter, the substrate 121 is also simply referred to as a "substrate 121." (See FIG. 9.) The configuration of the substrate 121 will be explained later.

[0255] The adhesive layer 120 is formed in contact with the electrode 118. The adhesive layer 120 The adhesive layer 120 may be a photo-curing adhesive, a reaction-curing adhesive, or a heat-curing adhesive. Adhesives such as epoxy resins, acrylic adhesives, or anaerobic adhesives can be used. In the case of a top emission structure, the adhesive layer 12 0, desiccants (such as zeolite) whose size is smaller than the wavelength of light, and fillers with a high refractive index (oxide By mixing titanium, zirconium, etc., the extraction efficiency of the light emitted by the EL layer 117 is improved. It is suitable for improving

[0256] [Removing the element formation substrate] Next, the element forming substrate 101 that is in contact with the insulating film 205 via the peeling layer 113 is removed from the insulating film 205. The peeling method involves applying mechanical force (using human hands). peeling with a tool or jig, separating by rotating a roller, ultrasonic, etc. For example, the peeling layer 113 may be cut with a sharp blade or by irradiating it with laser light. Insert the hair into the cut and pour water into the cut. Alternatively, spray a mist of water onto the cut. Water penetrates between the release layer 113 and the underlayer 119 due to the capillary phenomenon, and the element formation substrate The plate 101 can be easily peeled off.

[0257] [Bonding the substrates together] Next, the substrate 111 is bonded to the insulating film 205 via the adhesive layer 112 (see FIG. 11). In this way, the display device 100 can be manufactured. The same materials as in 20 can be used.

[0258] In this manner, the display device 100 can be fabricated.

[0259] The display device 100 described in this embodiment includes the transistor 431 and the transistor 233. In the non-overlapping region, the insulating film 108 and the insulating film 109 are partially removed. By removing the insulating film 108 and the insulating film 109, the display device 100 becomes more flexible. Therefore, a highly flexible display device can be realized. According to one aspect of the invention, the cable is less likely to break even when subjected to repeated bending operations. As a result, a highly reliable display device can be realized.

[0260] [Configuration of the opposing substrate] Next, the structure formed on the substrate 121 provided opposite to the substrate 111 will be described below. Make it clear.

[0261] First, a substrate 121 is prepared. The substrate 121 may be made of the same material as the substrate 111. Next, a light-shielding film 264 is formed on the substrate 121 (see FIG. 12(A)). Thereafter, a colored layer 266 is formed (see FIG. 12(B)).

[0262] The light-shielding film 264 and the colored layer 266 can be formed using various materials by a printing method, an ink-jet method, They are formed at desired positions using photolithography.

[0263] Next, an overcoat layer 268 is formed on the light-shielding film 264 and the colored layer 266 (FIG. 12 (See (C)).

[0264] The overcoat layer 268 may be made of, for example, acrylic resin, epoxy resin, polyimide, or the like. An organic insulating film can be used. By forming the overcoat layer 268, for example, For example, it is possible to prevent impurities contained in the colored layer 266 from diffusing toward the light emitting element 125. However, the overcoat layer 268 does not necessarily have to be provided. A structure in which the overcoat layer 268 is not formed may also be used.

[0265] Through the above steps, the structure formed on the substrate 121 can be formed.

[0266] [Method of film formation] The various films disclosed in this embodiment, such as metal films, semiconductor films, and inorganic insulating films, can be formed by sputtering or It can be formed by plasma CVD, but other methods, such as thermal CVD (Chemical CVD), are also possible. Alternatively, the film may be formed by a thermal vapor deposition (CVD) method. As an example, MOCVD (Metal Organic Chemical Vapor Deposition) Deposition) method and ALD (Atomic Layer Deposition) ) method may also be used.

[0267] The thermal CVD method is a film formation method that does not use plasma, so defects are generated by plasma damage. This has the advantage that it will not be

[0268] In the thermal CVD method, the source gas and oxidant are simultaneously fed into the chamber, and the pressure inside the chamber is increased to atmospheric pressure. The film is formed by reacting the material near or on the substrate under reduced pressure and depositing it on the substrate. It is also possible.

[0269] In the ALD method, the chamber is kept at atmospheric pressure or reduced pressure, and the source gases for the reaction are sequentially introduced. Next, the gas is introduced into the chamber, and the film may be formed by repeating this gas introduction sequence. For example, by switching between two or more types of switching valves (also called high-speed valves), The source gases are supplied to the chamber in order, and the first source gas is supplied to the chamber in order to prevent the mixture of the source gases. Inert gas (argon, nitrogen, etc.) is introduced simultaneously with or after the fuel gas. In case of simultaneously introducing an inert gas, the inert gas is The second source gas may be introduced as a carrier gas, and an inert gas may be introduced at the same time as the second source gas is introduced. Also, instead of introducing an inert gas, the first raw material gas is discharged by vacuum evacuation. The first source gas may be adsorbed on the surface of the substrate to form a first layer. The second layer is deposited on the first layer by reacting with the second source gas introduced later. This process is repeated several times while controlling the gas introduction order until a desired thickness is achieved. By doing so, a thin film with excellent step coverage can be formed. The thickness of the thin film is determined by the order of gas introduction. The thickness can be precisely adjusted by changing the number of times the process is repeated. This is suitable for producing thin FETs.

[0270] Thermal CVD methods such as MOCVD and ALD are suitable for forming metal films and semiconductor films disclosed in the present embodiment. It is possible to form various films such as inorganic insulating films. For example, an In-Ga-Zn-O film can be formed. When forming a film, trimethylindium, trimethylgallium, and dimethylzinc are used. The chemical formula of trimethylindium is In(CH3)3. The chemical formula for zinc is Ga(CH3)3. The chemical formula for dimethylzinc is Zn (CH3)2. In addition, the combination is not limited to these, and instead of trimethylgallium, Alternatively, triethylgallium (chemical formula Ga(C2H5)3) can be used, and dimethylgallium Diethylzinc (chemical formula Zn(C2H5)2) can also be used instead of lead.

[0271] For example, when forming a hafnium oxide film using a film formation device that uses ALD, the solvent and A liquid containing a hafnium precursor compound (hafnium alkoxide solution, typically tetrakis The raw material gas is vaporized trimethylsilyl dimethylamidohafnium (TDMAH) and oxidized Two types of gases are used: tetrakisdimethylamidohafnium (O3) and tetrakisdimethylamidohafnium (TDMHA). The chemical formula is Hf[N(CH3)2]4. Other material liquids include tetrakis(ethoxy) Examples include (trimethylamido) hafnium.

[0272] For example, when forming an aluminum oxide film using a film forming apparatus that uses ALD, the solvent and a liquid containing an aluminum precursor compound (e.g., trimethylaluminum (TMA)) Two types of gases are used: a source gas containing methyltrimethylsilyl methyl ... The chemical formula for aluminum is Al(CH3)3. Other liquid materials include Tris(diisopropyl alcohol). Methylamido) aluminum, triisobutylaluminum, aluminum tris(2, 2,6,6-tetramethyl-3,5-heptanedionate).

[0273] For example, when forming a silicon oxide film using a film forming device that uses ALD, The chlorine contained in the adsorbed material is removed, and the oxidizing gas (O2 , nitrous oxide) radicals are supplied to react with the adsorbate.

[0274] For example, when forming a tungsten film using a film forming device that uses ALD, WF6 gas is used. The initial tungsten film is formed by repeatedly introducing WF6 and B2H6 gases. The tungsten film is formed by simultaneously introducing B2H6 gas and H2 gas. Alternatively, SiH4 gas may be used.

[0275] For example, an oxide semiconductor film, such as In-Ga-Zn-O, can be formed using a film formation device that uses ALD. When forming a film, In(CH3)3 gas and O3 gas are introduced in sequence and repeatedly to form an In- Then, Ga(CH3)3 gas and O3 gas are introduced simultaneously to form a GaO layer. Then, Zn(CH3)2 gas and O3 gas are introduced simultaneously to form a ZnO layer. The order of these layers is not limited to this example. Alternatively, a mixed compound layer such as an In-Zn-O layer, an In-Zn-O layer, or a Ga-Zn-O layer may be formed. Instead of O3 gas, H2O gas obtained by bubbling with an inert gas such as Ar is used. However, it is preferable to use O3 gas that does not contain H. In(CH3)3 gas Alternatively, In(C2H5)3 gas may be used. Alternatively, Ga(C2H5)3 gas may be used. (C2H5)3 gas may be used, or Zn(CH3)2 gas may be used.

[0276] The structures and methods described in this embodiment may be appropriately combined with the structures and methods described in other embodiments. They can be used in combination.

[0277] (Embodiment 2) The configuration of the display device 100 having a top emission structure is modified to have a bottom emission structure. A display device 150 can be fabricated.

[0278] 13 shows an example of a cross-sectional configuration of a display device 150 with a bottom emission structure. 1A is a perspective view of the display device 100. In FIG. 1A, a portion indicated by a dashed line A1-A2 is shown. The display device 150 of the bottom emission structure has a light-shielding film 264 The positions of the color layer 266 and the overcoat layer 268 are different from those of the display device 100. .

[0279] In the display device 150, the light-shielding film 264, the colored layer 266, and the overcoat layer 26 8 is formed on a substrate 111.

[0280] In addition, the display device 150 having the bottom emission structure has the electrode 115 made of a light-transmitting conductive material. The electrode 118 is formed using a conductive material that efficiently reflects the light emitted by the EL layer 117. It is formed using an electrically conductive material.

[0281] The display device 150 transmits light 235 emitted from the EL layer 117 to the substrate via the colored layer 266. It can be launched from the 111 side.

[0282] As shown in FIG. 23, a touch sensor may be provided on the substrate 111, similarly to FIG. 22, a touch sensor may be provided on the substrate 921 as shown in FIG. It is also possible to do this.

[0283] The structures and methods described in this embodiment may be appropriately combined with the structures and methods described in other embodiments. They can be used in combination.

[0284] (Embodiment 3) Furthermore, by combining the display device 100 and the display device 150, the light emitted from the EL layer 117 The light 235 incident on the substrate 111 side is emitted from both the substrate 121 side. It is possible to realize a display device with a cushion structure (double-sided emission structure).

[0285] In addition, when forming a display device with a dual emission structure (double-sided emission structure), electrode 1 Both the electrode 15 and the electrode 118 may be formed using a light-transmitting conductive material.

[0286] The structures and methods described in this embodiment may be appropriately combined with the structures and methods described in other embodiments. They can be used in combination.

[0287] (Fourth embodiment) In this embodiment, the structure of the transistor 431 disclosed in the above embodiment will be described. 14A and 14B are a top view and a cross-sectional view of a transistor 431 as an example of a semiconductor device. The transistor 431 is a channel-etched transistor. 233 and the transistor 231 can have the same structure as the transistor 431. Cut.

[0288] FIG. 14A is a top view of the transistor 431. FIG. 14B is a top view of the transistor 431. 14(A) and FIG. 14(C) is a cross-sectional view of the portion indicated by the dashed line X1-X2 in FIG. 14(A). 14B is a cross-sectional view of a portion indicated by a dashed line Y1-Y2 of the transistor. 14(C) is a cross section of the transistor 431 in the channel length direction. This is a cross section in the width direction.

[0289] The transistor 431 includes a gate electrode 206, a gate insulating film 207, and a gate insulating film 208. The oxide semiconductor film 208 overlaps with the gate electrode 206 through the gate electrode 7, and the oxide semiconductor film 208 The gate insulating film 2 07, on the oxide semiconductor film 208, the source electrode 209a, and the drain electrode 209b A protective film 141 including the insulating films 108, 109, and 110 is formed. In addition, an electrode 226 overlapping with the oxide semiconductor film 208 is provided over the insulating film 110 .

[0290] The transistor 431 has a plurality of gate electrodes and an oxide semiconductor film 208 between the electrodes. The transistor has a dual gate structure having a channel width direction shown in FIG. In the above, an end of the electrode 226 is located outside the oxide semiconductor film 208. In the width direction, the electrode 226 extends beyond the end of the oxide semiconductor film 208 via the protective film 141. In addition, in the channel width direction, on the outside of the oxide semiconductor film 208, The gate electrode 206 and the electrode 226 face each other via the gate insulating film 207 and the protective film 141. do.

[0291] 14C, the gate electrode 206, the oxide semiconductor film 208, and the edge of the electrode 226 Explain the location.

[0292] Here, the distance between the end of the oxide semiconductor film 208 and the end of the electrode 226 is denoted by d. If the thickness of the protective film 41 is t, then d is preferably equal to or less than t of the protective film 141. By making the distance d between the end of the body membrane 208 and the end of the electrode 226 equal to or less than the distance t of the protective membrane 141, The edge of the oxide semiconductor film 208 can be influenced by the electric field of the electrode 226. The entire oxide semiconductor film 208 including the end portions can function as a channel.

[0293] The edge of the oxide semiconductor film 208 processed by etching or the like is damaged during the processing. Defects are formed and contamination occurs due to the adhesion of impurities, etc., which causes stresses such as electric fields. In other words, oxide semiconductors processed by etching, etc. The end portion of the conductive film is easily made n-type (low resistance).

[0294] The unintentionally n-type region is formed between the source electrode 209a and the drain electrode 209 When the source electrode 209a and the drain electrode 209b are in contact with each other, a desired Unintended current (also called "leakage current") flows. That is, this region functions as a parasitic channel.

[0295] However, as shown in FIG. 14C, the gate electrode 2 is formed outside the oxide semiconductor film 208. The end of the gate electrode 206 is located at the oxide semiconductor film 2 The occurrence of parasitic channels at the side surfaces of the 08 or at the edges including the side surfaces and their vicinity is suppressed. As a result, the drain current rises sharply when the gate voltage exceeds the threshold voltage. Therefore, a transistor having excellent electrical characteristics can be obtained.

[0296] The structures and methods described in this embodiment may be appropriately combined with the structures and methods described in other embodiments. They can be used in combination.

[0297] (Embodiment 5) In this embodiment, the transistor 231, the transistor 233, and the transistor 43 The structure of a transistor 200 that can be used in the semiconductor device 1 will be described with reference to FIG. do.

[0298] FIG. 15(A) is a top view of the transistor 200. FIG. 15(B) is a top view of the transistor 200. 15(A) and FIG. 15(C) is a cross-sectional view of the portion indicated by the dashed line X3-X4 in FIG. 15(A). 15B is a cross-sectional view of a portion indicated by a dashed line Y3-Y4 of the transistor. 15(C) is a cross section of the transistor 200 in the channel length direction, and FIG. 15(D) is a cross section of the transistor 200 in the channel length direction. This is a cross section in the width direction.

[0299] The transistor 200 is manufactured in a manner similar to that of the transistor 431 described in the above embodiment. However, the transistor 200 and the transistor 431 have the oxide semiconductor film 2 The shapes of the gate electrode 208 and the gate electrode 206 are different.

[0300] The transistor 200 has a gate voltage that varies not only in the channel width direction but also in the channel length direction. The end of the electrode 206 is positioned outside the end of the oxide semiconductor film 208 ( 15B). The gate electrode 206 is formed such that an end portion of the gate electrode 206 is in contact with the oxide semiconductor film 2 By positioning the transistor so that it is positioned outside the edge of the 08, the electrical characteristics of the transistor can be improved by light irradiation. This can further suppress gender fluctuations.

[0301] The structures and methods described in this embodiment may be appropriately combined with the structures and methods described in other embodiments. They can be used in combination.

[0302] (Embodiment 6) In this embodiment, the transistor 231, the transistor 233, and the transistor 43 The structure of a transistor 250 that can be used in the semiconductor device 1 will be described with reference to FIG. do.

[0303] FIG. 16(A) is a top view of the transistor 250. FIG. 16(B) is a top view of the transistor 250. 16(A) and FIG. 16(C) is a cross-sectional view of the portion indicated by the dashed line X5-X6 in FIG. 16(A). 16(D) is a cross-sectional view of the portion indicated by the dashed line Y5-Y6 in FIG. 16B is an enlarged view of a portion 290. Note that FIG. 16B shows the channel length of the transistor 250. 16(C) is a cross section in the channel width direction of the transistor 250. FIG.

[0304] The transistor 250 is manufactured in a manner similar to that of the transistor 431 described in the above embodiment. However, the transistor 250 does not include an oxide semiconductor film in contact with the oxide semiconductor film 208. A conductive film 218 is formed on the back gate electrode of the transistor 250. Although no functional electrode 226 is provided, the electrode 226 may be provided as needed. Needless to say.

[0305] The oxide semiconductor film 218 is composed of one or more metal elements that constitute the oxide semiconductor film 208. Therefore, the boundary between the oxide semiconductor film 208 and the oxide semiconductor film 218 Therefore, the movement of carriers is not hindered at the interface. Therefore, the field effect mobility is increased.

[0306] The oxide semiconductor film 218 is typically an In—Ga oxide, an In—Zn oxide, or an In—M -Zn oxide (M is Al, Ga, Y, Zr, La, Ce, or Nd) and oxidized The energy of the bottom of the conduction band is closer to the vacuum level than that of the oxide semiconductor film 208. The energy of the bottom of the conduction band of the oxide semiconductor film 208 The difference in energy between the 0.15 eV or more and 2 eV or less, 1 eV or less, 0.5 eV or less, or 0.4 eV or more That is, the electron affinity of the oxide semiconductor film 218 and the electron affinity of the oxide semiconductor film 208 are The difference between the sum force is 0.05 eV or more, 0.07 eV or more, 0.1 eV or more, or 0.15 eV or more and 2 eV or less, 1 eV or less, 0.5 eV or less, or 0.4 eV or less .

[0307] When the oxide semiconductor film 218 contains In, carrier mobility (electron mobility) is increased. preferable.

[0308] The oxide semiconductor film 218 may be formed by adding Al, Ga, Y, Zr, La, Ce, or Nd to an oxide semiconductor film 218. By having a higher atomic ratio, the following effects may be obtained: (1) Oxide semiconductor film 2 (2) increasing the energy gap of the oxide semiconductor film 218; (3) The diffusion of impurities from the outside is reduced. (4) Compared with the oxide semiconductor film 208, In addition, Ga, Y, Zr, La, Ce, and Nd bond with oxygen. Because they are metallic elements with strong combined forces, Ga, Y, Zr, La, Ce, or Nd are more highly By having a low atomic ratio, oxygen deficiency is less likely to occur.

[0309] When the oxide semiconductor film 218 is an In-M-Zn oxide, the sum of In and M is 100a. When the atomic percentage is 50 atomic %, the atomic ratio of In to M is preferably 50 atomic %. %, M is 50 atomic % or more, and more preferably In is less than 25 atomic %. M must be 75 atomic% or more.

[0310] In addition, the oxide semiconductor film 208 and the oxide semiconductor film 218 are made of In-M-Zn oxide (M is Ga, Y, Zr, La, Ce, or Nd), compared with the oxide semiconductor film 208 The element of M (Ga, Y, Zr, La, Ce, or Nd) contained in the oxide semiconductor film 218 The atomic ratio is large, typically, 1 compared to the above atoms contained in the oxide semiconductor film 208. The atomic ratio is 0.5 times or more, preferably 2 times or more, and more preferably 3 times or more higher.

[0311] In addition, the oxide semiconductor film 208 and the oxide semiconductor film 218 are made of In-M-Zn oxide (M is Al, Ga, Y, Zr, La, Ce, or Nd), the oxide semiconductor film 218 is n:M:Zn=x1:y1:z1 [atomic ratio], and the oxide semiconductor film 208 was In:M:Zn = x2:y2:z2 [atomic ratio], y1 / x1 is larger than y2 / x2, and is preferred. Preferably, y1 / x1 is 1.5 times or more greater than y2 / x2. x1 is at least twice as large as y2 / x2, and more preferably, y1 / x1 is larger than y2 / x2. In this case, when y2 is equal to or larger than x2 in the oxide semiconductor film, This is preferable because stable electrical characteristics can be imparted to a transistor including an oxide semiconductor film. However, when y2 is three times or more of x2, the electric field of the transistor using the oxide semiconductor film Since the effective mobility is reduced, y2 is preferably less than three times x2.

[0312] The oxide semiconductor film 208 is an In-M-Zn oxide (M is Ga, Y, Zr, La, Ce, or In the case of Nd), the oxide semiconductor film 208 is formed using a target containing Nd and / or Nd. If the atomic ratio of metal elements is In:M:Zn=x1:y1:z1, 、 x1 / y1 is 1 / 3 or more and 6 or less, further 1 or more and 6 or less, and z1 / y1 is 1 / 3 or more and 6 or less, further It is preferable that z1 / y1 is 1 or more and 6 or less. Therefore, a CAAC-OS film is easily formed as the oxide semiconductor film 208. Typical examples of atomic ratios of group elements are In:M:Zn=1:1:1 and In:M:Zn=5 :5:6, In:M:Zn=2:1:2, In:M:Zn=3:1:2, etc.

[0313] The oxide semiconductor film 218 is an In-M-Zn oxide (M is Ga, Y, Zr, La, Ce, or In the case of Nd), the target used for depositing the oxide semiconductor film 218 is If the atomic ratio of metal elements is In:M:Zn=x2:y2:z2, 、 x2 / y2 <x1 / y1, z2 / y2 is preferably 1 / 3 or more and 6 or less, and more preferably 1 or more and 6 or less. When z2 / y2 is 1 or more and 6 or less, the oxide semiconductor film 218 can be formed of C AAC-OS film is easily formed. Typical examples of the atomic ratio of the target metal elements are: are In:M:Zn=1:3:2, In:M:Zn=1:3:4, In:M:Zn=1: 3:6, In:M:Zn=1:3:8, etc.

[0314] The atomic ratios of the oxide semiconductor film 208 and the oxide semiconductor film 218 are each determined by an error The atomic ratios listed above may vary by ±40%.

[0315] The thickness of the oxide semiconductor film 218 is greater than or equal to 3 nm and less than or equal to 100 nm, preferably greater than or equal to 3 nm and less than or equal to 50 nm. Let nm.

[0316] Similarly to the oxide semiconductor film 208, the oxide semiconductor film 218 has a non-single-crystal structure, for example. The non-single crystal structure may be a CAAC structure, a polycrystalline structure, a microcrystalline structure, or an amorphous structure. Includes structure.

[0317] The oxide semiconductor film 218 may have, for example, an amorphous structure. For example, the atomic arrangement is disordered and does not have crystalline components. Alternatively, the oxide film has an amorphous structure. For example, the amorphous structure of the crystalline silicon film is completely amorphous and does not have any crystalline portions.

[0318] Note that the oxide semiconductor film 208 and the oxide semiconductor film 218 form an amorphous region, It has two or more of the following structures: a microcrystalline structure region, a polycrystalline structure region, a CAAC structure region, and a single crystal structure region. The mixed film may have, for example, an amorphous structure region, a microcrystalline structure region, and , a polycrystalline structure region, a CAAC structure region, and a single crystal structure region. The mixed film may have, for example, an amorphous structure region, a microcrystalline structure region, Two or more of the following regions: polycrystalline structure region, CAAC structure region, and single crystal structure region It may have a laminated structure.

[0319] Here, an oxide semiconductor film 218 is provided between the oxide semiconductor film 208 and the insulating film 108. Therefore, impurities and Even if trap states are formed due to defects, the trap states and the oxide semiconductor film 208 As a result, electrons flowing through the oxide semiconductor film 208 are transported to the trap states. This makes it possible to increase the on-state current of the transistor and also to In addition, when an electron is captured in the trap level, the electron This results in a negative fixed charge. As a result, the threshold voltage of the transistor fluctuates. However, because there is a gap between the oxide semiconductor film 208 and the trap states, Therefore, it is possible to reduce the trapping of electrons in the trap level, and the fluctuation of the threshold voltage can be reduced.

[0320] In addition, the oxide semiconductor film 218 can block impurities from the outside. It is possible to reduce the amount of impurities that move from the oxide semiconductor film 208 to the oxide semiconductor film 208. For these reasons, the oxide semiconductor film 208 is less likely to form oxygen vacancies. It is possible to reduce the impurity concentration and oxygen vacancy in the silicon substrate.

[0321] Note that the oxide semiconductor film 208 and the oxide semiconductor film 218 are not simply stacked. The structure is a continuous junction (here, the energy of the bottom of the conduction band changes continuously between each film). In other words, trap centers and recrystallization sites are formed at the interfaces of each film. The layer structure is such that there are no impurities that form defect levels such as a junction center. Impurities are mixed between the stacked oxide semiconductor films 208 and 218. If the interface is too thick, the continuity of the energy band is lost, and carriers are trapped at the interface, or They recombine and disappear.

[0322] To form continuous junctions, a multi-chamber deposition system equipped with a load lock chamber is required. (sputtering equipment) to continuously stack each film without exposing it to the air. Each chamber in the sputtering device is indispensable for the oxide semiconductor film. An adsorption type vacuum pump such as a cryopump is used to remove as much water as possible. High vacuum pumping (5×10 -7 Pa~1×10 -4 It is preferable to Alternatively, a turbomolecular pump and cold trap can be combined to evacuate the chamber from the exhaust system. It is preferable to prevent gases, especially gases containing carbon or hydrogen, from flowing back into the .

[0323] In the process of forming the source electrode 209a and the drain electrode 209b, the oxide semiconductor film The surface of 218 may be etched.

[0324] [Band structure diagram] FIG. 17 is a schematic diagram showing the band structure of the region indicated by the dashed line Z1-Z2 in FIG. 16(D). EcI1 shown in FIG. 17 indicates the energy of the bottom of the conduction band of the gate insulating film 207. EcS1 represents the energy of the bottom of the conduction band of the oxide semiconductor film 208, and EcS2 represents the energy of the bottom of the conduction band of the oxide semiconductor film 208. EcI2 indicates the energy of the bottom of the conduction band of the insulating film 108. The energy at the edge is shown.

[0325] As shown in FIG. 17, at the junction between the oxide semiconductor film 208 and the oxide semiconductor film 218, In other words, the energy at the bottom of the conduction band changes smoothly. This can be said to be because the oxide semiconductor film 208 and the oxide semiconductor film 218 have a common The oxide semiconductor film 208 and the oxide semiconductor film 218 contain a metal element, and oxygen is mixed between the oxide semiconductor film 208 and the oxide semiconductor film 218. This can be said to be because a mixed layer is formed when the water moves to the

[0326] As shown in FIG. 17, the oxide semiconductor film 208 serves as a well, and the channel region is formed of the oxide semiconductor. It can be seen that the oxide semiconductor film 208 is formed on the oxide semiconductor film 208. The film 218 has a continuously changing energy level at the bottom of the conduction band. In other words, the oxide semiconductor film 8 and the oxide semiconductor film 218 are in continuous contact with each other.

[0327] In the process of forming the source electrode 209a and the drain electrode 209b, an oxide semiconductor The surface of the insulating film 218 may be etched. A trap level due to impurities or defects may be formed near the interface with the film 108. In addition, the oxide semiconductor film 218 is provided, so that the oxide semiconductor film 208 and the oxide semiconductor film 218 are However, the energy difference between EcS1 and EcS2 ( When dEcS is small, electrons in the oxide semiconductor film 208 can exceed the energy difference and be tracked. When electrons are captured in the trap level, they form mi- crons at the interface of the insulating film. A fixed charge is generated, and the threshold voltage of the transistor shifts in the positive direction. Therefore, the energy difference (dEcS) between EcS1 and EcS2 is preferably 0.1 eV or more. Preferably, when the value is 0.15 eV or more, the fluctuation of the threshold voltage of the transistor is reduced, and the stability is improved. This is preferable because it results in stable electrical properties.

[0328] The structures and methods described in this embodiment may be appropriately combined with the structures and methods described in other embodiments. They can be used in combination.

[0329] (Embodiment 7) In this embodiment, a structural example of a light-emitting element that can be used as the light-emitting element 125 will be described. Note that the EL layer 320 in this embodiment may be the same as the EL layer 117 in other embodiments. is equivalent to

[0330] <Configuration of light-emitting element> The light-emitting element 330 shown in FIG. 18(A) has an EL element between a pair of electrodes (electrode 318 and electrode 322). In the following description of this embodiment, the layer 320 is taken as an example. Electrode 318 is used as an anode and electrode 322 is used as a cathode.

[0331] The EL layer 320 may be formed to include at least a light-emitting layer. The functional layer other than the light-emitting layer may be a layered structure including a functional layer having a high hole injection property. materials with high hole transporting properties, materials with high electron transporting properties, materials with high electron injecting properties, bipolar A layer containing a material having high electron and hole transport properties can be used. In practice, functional layers such as a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer are appropriately combined. It can be used as such.

[0332] The light-emitting element 330 shown in FIG. 18(A) emits light in response to a potential difference generated between the electrode 318 and the electrode 322. This allows current to flow, and holes and electrons recombine in the EL layer 320, causing light to be emitted. In other words, the EL layer 320 is configured to have a light-emitting region.

[0333] In the present invention, light emitted from the light emitting element 330 is emitted from the electrode 318 or electrode 322 side. Therefore, either the electrode 318 or the electrode 322 has a light-transmitting property. It consists of a substance that

[0334] The EL layer 320 is connected to the electrode 318 and the electrode 331 as in the light-emitting element 331 shown in FIG. 18(B). 22 may be laminated in multiple layers. In this case, it is preferable to provide charge generation layers 320a between the m-th (where m is a natural number satisfying 1 ≤ m < n) EL layer 320 and the (m + 1) -th EL layer 320, respectively.

[0335] The charge generation layer 320a can be formed by appropriately combining, in addition to a composite material of an organic compound and a metal oxide, a metal oxide, a composite material of an organic compound and an alkali metal, an alkaline earth metal, or a compound thereof. As the composite material of an organic compound and a metal oxide, for example, it contains a composite material of an organic compound and a metal oxide such as vanadium oxide, molybdenum oxide, or tungsten oxide. As the organic compound, various compounds can be used, such as aromatic amine compounds, carbazole derivatives, low molecular weight compounds such as aromatic hydrocarbons, or oligomers, dendrimers, polymers, etc. of these low molecular weight compounds. In addition, as the organic compound, a hole transport organic compound with a hole mobility of 10 cm / Vs or more is preferably applied. However, as long as it is a substance with higher hole transportability than electrons, other substances can be used. These materials used for the charge generation layer 320a are excellent in carrier injection properties and carrier transport properties, so low current driving and low voltage driving of the light emitting element 330 can be realized. -6 cm 2 / Vs or more is preferably applied. However, as long as it is a substance with higher hole transportability than electrons, other substances can be used. These materials used for the charge generation layer 320a are excellent in carrier injection properties and carrier [[ID=二十八]] transport properties, so low current driving and low voltage driving of the light emitting element 330 can be realized. transport properties, so low current driving and low voltage driving of the light emitting element 330 can be realized. In addition, the charge generation layer 320a may be formed by combining a composite material of an organic compound and a metal oxide with other materials. For example, a layer containing a composite material of an organic compound and a metal oxide and a layer containing a compound selected from electron donors and a compound with high electron transportability may be combined. [[ID=3'']]

[0336] In addition, the charge generation layer 320a may be formed by combining a composite material of an organic compound and a metal oxide with other materials. For example, a layer containing a composite material of an organic compound and a metal oxide and a layer containing a compound selected from electron donors and a compound with high electron transportability may be combined. In addition, the charge generation layer 320a may be formed by combining a composite material of an organic compound and a metal oxide with other materials. For example, a layer containing a composite material of an organic compound and a metal oxide and a layer containing a compound selected from electron donors and a compound with high electron transportability may be combined. In addition, the charge generation layer 320a may be formed by combining a composite material of an organic compound and a metal oxide with other materials. For example, a layer containing a composite material of an organic compound and a metal oxide and a layer containing a compound selected from electron donors and a compound with high electron transportability may be combined. In addition, the charge generation layer 320a may be formed by combining a composite material of an organic compound and a metal oxide with other materials. For example, a layer containing a composite material of an organic compound and a metal oxide and a layer containing a compound selected from electron donors and a compound with high electron transportability may be combined.

[0337]

[0338]

[0339]

[0340]

[0341]

[0342]

[0343]

[0344]

[0345]

[0346] [[ID=A]]

[0347]

[0348]

[0349]

[0350] [[ID=B]]

[0351]

[0352]

[0353]

[0354]

[0355] [[ID=E]]

[0356]

[0357]

[0358]

[0359]

[0360]

[0361]

[0362] [[ID=17 may be formed in combination with each other.

[0337] The light emitting element 331 having such a configuration may have problems such as energy transfer and quenching. It is difficult to achieve this, and the range of materials to choose from is widened, making it possible to create a light-emitting element that has both high luminous efficiency and a long life. It is also easy to obtain phosphorescence in one light-emitting layer and fluorescence in the other. is.

[0338] The charge generating layer 320a is a layer that generates a charge when a voltage is applied between the electrode 318 and the electrode 322. The electron-generating layer 320a has a function of injecting holes into the EL layer 320 formed in contact with the electron-generating layer 320a. The other EL layer 320 has a function of injecting electrons.

[0339] The light-emitting element 331 shown in FIG. 18B can be realized by changing the type of light-emitting material used in the EL layer 320. In addition, it is possible to obtain various luminescent colors by using a plurality of luminescent materials with different luminescent colors. By using luminescent materials, it is possible to obtain broad spectrum luminescence and white luminescence. do.

[0340] When white light is to be emitted using the light-emitting element 331 shown in FIG. 18(B), a combination of a plurality of EL layers is used. In combination, it is sufficient if the configuration includes red, blue, and green light and emits white light. For example, The light-emitting layer contains a blue fluorescent material as a light-emitting material, and the light-emitting layer contains green and red phosphorescent materials as light-emitting materials. In addition, a light-emitting layer that emits red light and a light-emitting layer that emits green light may be used. Alternatively, the light-emitting layer may have a structure including a light-emitting layer that emits blue light and a light-emitting layer that emits red light. White light can be obtained even if the device has a light-emitting layer that emits light of complementary colors. In a stacked element in which two layers are stacked, the color of the light emitted from the light-emitting layer and the color of the light emitted from the light-emitting layer are When the colors of the emitted light are complementary to each other, the complementary colors are blue and yellow, or Examples include blue-green and red.

[0341] In the configuration of the above-mentioned stacked element, a charge generating layer may be disposed between the stacked light emitting layers. By doing so, it is possible to realize a long-life element in the high-brightness region while maintaining a low current density. In addition, the voltage drop due to the resistance of the electrode material can be reduced, allowing for uniform generation over a large area. Light becomes possible.

[0342] The structures and methods described in this embodiment may be appropriately combined with the structures and methods described in other embodiments. They can be used in combination.

[0343] (Embodiment 8) In this embodiment, examples of electronic devices and lighting devices to which the display device of one embodiment of the present invention is applied will be described. This will be explained with reference to the drawings.

[0344] As an example of an electronic device to which a display device having a flexible shape is applied, a television equipment (also called television or television receiver), monitors for computers, digital barrel cameras, digital video cameras, digital photo frames, mobile phones (mobile phones, (also called mobile phone devices), portable game machines, personal digital assistants, audio playback devices, pachinko machines, etc. Examples include large game consoles.

[0345] In addition, lighting devices and display devices can be installed on the interior or exterior walls of houses and buildings, or on the interior or exterior of automobiles. It is also possible to incorporate it along the curved surface of the

[0346] FIG. 19A shows an example of a mobile phone. The mobile phone 7400 has a housing 7401. In addition to the display unit 7402 incorporated in the The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, etc. The device is used in the display portion 7402 .

[0347] In a mobile phone 7400 shown in FIG. 19A, information can be displayed by touching a display portion 7402 with a finger or the like. You can also make calls, enter text, or do any other actions. An operation can be performed by touching the display portion 7402 with a finger or the like.

[0348] Also, by operating the operation button 7403, the power can be turned on and off, and the display unit 7402 can be displayed. For example, from the email creation screen, you can change the type of image displayed. - You can switch to the screen.

[0349] Here, the display device of one embodiment of the present invention is incorporated in the display portion 7402. As a result, a highly reliable mobile phone can be provided with a curved display.

[0350] FIG. 19B shows an example of a wristband-type display device. The device includes a housing 7101, a display unit 7102, operation buttons 7103, and a transmitting / receiving device 7104. can.

[0351] The portable display device 7100 can receive a video signal by the transmitting / receiving device 7104. Video can be displayed on the display unit 7102. Audio signals can also be transmitted to other receiving devices. It is also possible to do so.

[0352] In addition, the operation button 7103 can be used to turn the power on and off and to switch the displayed image. , or adjust the volume of the audio.

[0353] Here, the display device of one embodiment of the present invention is incorporated in the display portion 7102. As a result, a highly reliable portable display device can be provided that has a curved display portion.

[0354] 19(C) to 19(E) show an example of a lighting device. The lighting device 7210 and the illumination device 7220 are each mounted on a base 72 having an operation switch 7203. 01 and a light emitting part supported by a base part 7201.

[0355] The lighting device 7200 shown in FIG. 19(C) includes a light-emitting unit 7202 having a wavy light-emitting surface. This makes it a highly designed lighting device.

[0356] The light-emitting portion 7212 of the lighting device 7210 shown in FIG. 19(D) has two convexly curved The light emitting units are arranged symmetrically. It can illuminate the direction.

[0357] The lighting device 7220 shown in FIG. 19(E) includes a light-emitting portion 7222 that is curved in a concave shape. Therefore, in order to collect light emitted from the light emitting portion 7222 onto the front surface of the lighting device 7220, It is suitable for brightly lighting an area.

[0358] Furthermore, the light-emitting units of the lighting devices 7200, 7210, and 7220 Since the light emitting part is flexible, it can be attached to a plastic member or a movable frame. The light emitting portion may be fixed with a member, and the light emitting surface of the light emitting portion may be freely curved depending on the application.

[0359] Here, the light emitting devices 7200, 7210, and 7220 are The display device according to one embodiment of the present invention is incorporated in the curved display unit. Therefore, a highly reliable lighting device can be obtained.

[0360] An example of a portable display device is shown in FIG. 20A. The display device 7300 includes a housing 7301, It includes a display unit 7302, operation buttons 7303, a drawer member 7304, and a control unit 7305. .

[0361] The display device 7300 is a flexible display unit rolled up in a cylindrical housing 7301. Equipped with 7302.

[0362] The display device 7300 can receive a video signal through the control unit 7305. can be displayed on the display unit 7302. The control unit 7305 is equipped with a battery. In addition, the control unit 7305 can be equipped with a connector to directly supply video signals and power. good.

[0363] In addition, the operation button 7303 can be used to turn the power on and off and to switch the displayed image. etc. can be done.

[0364] FIG. 20B shows a state in which the display portion 7302 is pulled out by a pull-out member 7304 . In this state, an image can be displayed on the display portion 7302. The provided operation button 7303 allows for easy operation with one hand.

[0365] In order to prevent the display portion 7302 from bending when the display portion 7302 is pulled out, A frame for reinforcement may be provided at the end of 2.

[0366] In addition to this configuration, a speaker is provided on the housing, and the sound is transmitted by the audio signal received together with the video signal. The audio may be output by the audio input.

[0367] The display device of one embodiment of the present invention is incorporated in the display portion 7302. Since the unit 7302 is a flexible and reliable display device, the display device 7300 A lightweight and highly reliable display device can be obtained.

[0368] Note that the display device of one embodiment of the present invention can be used in the electronic devices and lighting devices described above. It goes without saying that there is no particular limitation.

[0369] The structures and methods described in this embodiment may be appropriately combined with the structures and methods described in other embodiments. They can be used in combination. [Explanation of symbols]

[0370] 100 display device 101 Element formation substrate 108 insulating film 109 insulating film 110 insulating film 111 Substrate 112 Adhesive layer 113 Peeling layer 114 Bulkhead 115 Electrode 116 Terminal electrode 117 EL layer 118 Electrode 119 Base layer 120 Adhesive layer 121 PCB 122 Opening 123 Anisotropic Conductive Interconnect Layer 124 External electrode 125 Light-emitting element 131 Display area 132 Drive circuit 133 Drive circuit 134 pixels 135 scan lines 136 Signal Line 141 Protective film 142 Opening 143 Opening 145 Conductive Film 150 Display device

Claims

1. a display area having a plurality of pixels arranged in a matrix; At least one of the plurality of pixels includes a first transistor and a capacitance element, a display device, wherein one of a source electrode and a drain electrode of the first transistor is electrically connected to one electrode of the capacitor; a first oxide semiconductor layer having a region in contact with a top surface of the first insulating layer and including a channel formation region of the first transistor; a first conductive layer having a region overlapping with the first oxide semiconductor layer and functioning as a first gate electrode of the first transistor; a second conductive layer having a region overlapping with the first oxide semiconductor layer and functioning as a second gate electrode of the first transistor; a third conductive layer having a region in contact with a top surface of the first oxide semiconductor layer and functioning as one of a source electrode and a drain electrode of the first transistor; a second oxide semiconductor layer having a region in contact with a top surface of the first insulating layer and functioning as one electrode of the capacitor; a fourth conductive layer having the same material as the second conductive layer and functioning as the other electrode of the capacitor; a second insulating layer having a region in contact with a lower surface of the second conductive layer and a region in contact with a lower surface of the fourth conductive layer; The display device, wherein the second oxide semiconductor layer contains the same material as the first oxide semiconductor layer.

2. a display area having a plurality of pixels arranged in a matrix; At least one of the plurality of pixels includes a first transistor, a second transistor, and a capacitance element; one of a source electrode and a drain electrode of the first transistor is electrically connected to one electrode of the capacitance element; a display device, wherein one of a source electrode and a drain electrode of the first transistor is electrically connected to a gate electrode of the second transistor; a first oxide semiconductor layer having a region in contact with a top surface of the first insulating layer and including a channel formation region of the first transistor; a first conductive layer having a region overlapping with the first oxide semiconductor layer and functioning as a first gate electrode of the first transistor; a second conductive layer having a region overlapping with the first oxide semiconductor layer and functioning as a second gate electrode of the first transistor; a third conductive layer having a region in contact with a top surface of the first oxide semiconductor layer and functioning as one of a source electrode and a drain electrode of the first transistor; a second oxide semiconductor layer having a region in contact with a top surface of the first insulating layer and functioning as one electrode of the capacitor; a fourth conductive layer having the same material as the second conductive layer and functioning as the other electrode of the capacitor; a second insulating layer having a region in contact with a lower surface of the second conductive layer and a region in contact with a lower surface of the fourth conductive layer; The display device, wherein the second oxide semiconductor layer contains the same material as the first oxide semiconductor layer.

Images