JP2006106106A - Liquid crystal display and method for fabricating the same, and liquid crystal television set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for fabricating a liquid crystal display, having a high speed TFT in which the utilization factor of a material is improved, where only a small number of photomasks is required and deviation of the threshold hardly occurs. <P>SOLUTION: A catalyst element is added to an amorphous semiconductor film and heated to form a crystalline semiconductor film, and the catalyst element is removed from the crystalline semiconductor film, and subsequently, an inverted staggered thin-film transistor is fabricated. Also, simplification of the steps and reduction of loss for the materials are achieved, by forming a gate electrode layer of the thin-film transistor and a pixel electrode layer using the same step and the same material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a liquid crystal display device and a liquid crystal television device using the same.

  In recent years, a flat panel display (FPD) represented by a liquid crystal display (LCD) has attracted attention as a display device that replaces the conventional CRT. In particular, the development of a large-screen liquid crystal television apparatus equipped with a large liquid crystal panel driven by an active matrix has become an important issue for liquid crystal panel manufacturers to focus on.

    In a conventional liquid crystal display device, a thin film transistor (hereinafter also referred to as TFT) using amorphous silicon is used as a semiconductor element for driving each pixel.

On the other hand, in conventional liquid crystal televisions, image blurring due to the limitation of viewing angle characteristics and the limitation of high-speed operation due to liquid crystal materials and the like has been a drawback. In recent years, OCB (optically compensated bend) mode has been proposed (see Non-Patent Document 1).
Nagahiro Yasuaki et al., “Nikkei Microdevices separate volume flat panel display 2002”, Nikkei BP, October 2001, P102-109

However, when a TFT using an amorphous semiconductor film is DC-driven, the threshold value tends to shift and TFT characteristic variation tends to occur accordingly. For this reason, luminance unevenness occurs in a display device in which a TFT using an amorphous semiconductor film is used for pixel switching. Such a phenomenon becomes more conspicuous as a large-screen television apparatus having a diagonal of 30 inches or more (typically 40 inches or more), and deterioration in image quality is a serious problem.

  On the other hand, there is a need for a switching element that can operate at high speed in order to improve the image quality of the LCD. However, a TFT using an amorphous semiconductor film has a limit. For example, it is difficult to realize an OCB mode liquid crystal display device.

  The present invention has been made in view of such a situation, and provides a method for manufacturing a liquid crystal display device having a TFT which can be operated at high speed without causing a threshold shift with a small number of photomasks. In addition, a method for manufacturing a liquid crystal display device which can display with high switching characteristics and high contrast is provided.

  In order to solve the above-described problems of the prior art, the following measures are taken in the present invention.

  The present invention adds an element that promotes or promotes crystallization (hereinafter, also referred to as a metal element or a catalyst element because it mainly refers to a metal element) to form an amorphous semiconductor film, and a semiconductor film having a group 15 element Alternatively, a semiconductor film containing a rare gas element is formed, heated to form a crystalline semiconductor film, and a metal element is removed from the crystalline semiconductor film at the same time, and then an inverted staggered thin film transistor is formed. . Note that in the case where a semiconductor film containing a Group 15 element is formed in the crystalline semiconductor film, an n-channel thin film transistor is formed using the semiconductor film containing a Group 15 element as a source region and a drain region. Further, a p-channel thin film transistor is formed by adding a group 13 element as an impurity element imparting p-type to a semiconductor film having a group 15 element as an impurity element imparting n-type. Further, when a semiconductor film containing a rare gas element is formed, the semiconductor film containing the rare gas element is removed after heating, and a source region and a drain region are formed, so that an n-channel thin film transistor or a p-channel thin film transistor is formed. To do.

    In the present invention, a gate electrode layer and a pixel electrode layer of a thin film transistor are formed using the same material in the same process, thereby achieving simplification of the process and reduction of material loss.

    One aspect of the liquid crystal display device of the present invention has a gate electrode layer and a pixel electrode layer provided on an insulating surface, has a first gate insulating layer on the gate electrode layer, and is on the first gate insulating layer. A second gate insulating layer, a third gate insulating layer on the second gate insulating layer, a crystalline semiconductor layer on the third gate insulating layer, and a crystalline semiconductor layer A semiconductor layer having one conductivity type in contact therewith, a source electrode layer and a drain electrode layer in contact with the semiconductor layer having one conductivity, and an insulating layer formed on the source electrode layer, the drain electrode layer, and the pixel electrode layer; The insulating layer has a first opening reaching the source electrode layer or the drain electrode layer, the gate insulating layer and the insulating layer have a second opening reaching the pixel electrode layer, and the first opening The source electrode layer or the drain electrode layer and the pixel electrode layer are electrically connected to the second opening. Having a wiring layer connected.

    One aspect of the liquid crystal display device of the present invention has a gate electrode layer and a pixel electrode layer provided on an insulating surface, has a first gate insulating layer on the gate electrode layer, and is on the first gate insulating layer. A crystalline semiconductor layer having a second gate insulating layer, a third gate insulating layer on the second gate insulating layer, and a source region and a drain region provided on the third gate insulating layer A source electrode layer and a drain electrode layer in contact with the source region and the drain region, an insulating layer on the source electrode layer, the drain electrode layer and the pixel electrode layer, wherein the insulating layer is a source electrode A first opening reaching the layer or drain electrode layer, the gate insulating layer and the insulating layer have a second opening reaching the pixel electrode layer, and the first opening and the second opening, The source or drain electrode layer and the pixel electrode layer are electrically connected Having a wiring layer continue to.

    One aspect of the liquid crystal display device of the present invention has a pixel region and a driver circuit region over the same substrate, and has a first gate electrode layer and a second gate electrode layer over the substrate in the driver circuit region, A first gate insulating layer over the first gate insulating layer, a second gate insulating layer over the first gate insulating layer, and a second gate insulating layer over the second gate insulating layer. 3 gate insulating layers, and the first crystalline semiconductor layer and the second crystalline semiconductor layer are provided on the third gate insulating layer, and the n-type is in contact with the first crystalline semiconductor layer. A semiconductor layer; a semiconductor layer having a p-type in contact with the first crystalline semiconductor layer; and a first source electrode layer and a first drain electrode layer in contact with the semiconductor layer having an n-type , Having a second source electrode layer and a second drain electrode layer in contact with the p-type semiconductor layer, in the pixel region There has a pixel electrode layer on the substrate.

    In one embodiment of the liquid crystal display device of the present invention, a gate electrode layer and a pixel electrode layer are formed over an insulating surface, a gate insulating layer is formed over the gate electrode layer and the pixel electrode layer, and a metal element is included over the gate insulating layer Forming a metal layer; forming a semiconductor layer over the metal layer; forming a semiconductor layer having one conductivity type in contact with the semiconductor layer; heating the semiconductor layer and the semiconductor layer having one conductivity type; A source electrode layer and a drain electrode layer are formed in contact with the semiconductor layer, and a semiconductor layer having one conductivity type is patterned to form a source region and a drain region, over the source electrode layer, the drain electrode layer, and the gate insulating layer An insulating layer is formed, a first opening reaching the source electrode layer or the drain electrode layer is formed in the insulating layer, and a second opening reaching the pixel electrode layer is formed in the insulating layer and the gate insulating layer. And second opening To form a wiring layer for electrically connecting the source or drain electrode layer and the pixel electrode layer.

    In one embodiment of the liquid crystal display device of the present invention, a gate electrode layer and a pixel electrode layer are formed over an insulating surface, a gate insulating layer is formed over the gate electrode layer and the pixel electrode layer, and a semiconductor layer is formed over the gate insulating layer A metal element is added to the semiconductor layer, a semiconductor layer having one conductivity type is formed in contact with the semiconductor layer, the semiconductor layer and the semiconductor layer having one conductivity type are heated, and the semiconductor layer having one conductivity type is in contact with the semiconductor layer. Forming a source electrode layer and a drain electrode layer, patterning a semiconductor layer having one conductivity type, forming a source region and a drain region, and forming an insulating layer on the source electrode layer, the drain electrode layer, and the gate insulating layer Then, a first opening reaching the source or drain electrode layer is formed in the insulating layer, and a second opening reaching the pixel electrode layer is formed in the insulating layer and the gate insulating layer, and the first opening and the second opening are formed. In the opening of the The source electrode layer or the drain electrode layer and the pixel electrode layer to form a wiring layer electrically connected.

    In one embodiment of the liquid crystal display device of the present invention, a gate electrode layer and a pixel electrode layer are formed over an insulating surface, a gate insulating layer is formed over the gate electrode layer and the pixel electrode layer, and a metal element is included over the gate insulating layer Forming a metal layer, forming a semiconductor layer on the metal layer, selectively forming a channel protective layer on the semiconductor layer, forming a semiconductor layer having one conductivity type in contact with the semiconductor layer and the channel protective layer; The semiconductor layer, the channel protective layer, and the semiconductor layer having one conductivity type are heated, a source electrode layer and a drain electrode layer are formed in contact with the semiconductor layer having one conductivity type, and the semiconductor layer having one conductivity type is patterned. Forming a source region and a drain region, forming an insulating layer over the source electrode layer, the drain electrode layer, and the gate insulating layer; and a first opening reaching the source electrode layer or the drain electrode layer in the insulating layer, and the insulating layer When A second opening reaching the pixel electrode layer is formed in the gate insulating layer, and the source or drain electrode layer and the pixel electrode layer are electrically connected to the first opening and the second opening. Form a layer.

    In one embodiment of the liquid crystal display device of the present invention, a gate electrode layer and a pixel electrode layer are formed over an insulating surface, a gate insulating layer is formed over the gate electrode layer and the pixel electrode layer, and a semiconductor layer is formed over the gate insulating layer A channel protective layer is selectively formed over the semiconductor layer, a metal element is added to the semiconductor layer and the channel protective layer, and a semiconductor layer having one conductivity type is formed in contact with the semiconductor layer and the channel protective layer. A layer, a channel protective layer, and a semiconductor layer having one conductivity type are heated, a source electrode layer and a drain electrode layer are formed in contact with the semiconductor layer having one conductivity type, and the semiconductor layer having one conductivity type is patterned, A source region and a drain region; an insulating layer is formed over the source electrode layer, the drain electrode layer, and the gate insulating layer; a first opening reaching the source electrode layer or the drain electrode layer; A second opening reaching the pixel electrode layer is formed in the layer and the gate insulating layer, and the source or drain electrode layer and the pixel electrode layer are electrically connected to the first opening and the second opening. A wiring layer is formed.

  According to the present invention, an inverted staggered TFT formed of a crystalline semiconductor film can be formed with a small number of photomasks. The inversely staggered TFT of the present invention can simultaneously perform a crystallization process of an amorphous semiconductor film and a gettering process of a metal catalyst for promoting crystallization of the amorphous semiconductor film. The number of processes can be reduced. In particular, since the number of heat treatments can be reduced, energy saving can be achieved and throughput can be improved.

  In addition, the inverted staggered TFT of the present invention uses a material having high heat resistance for the gate electrode, and uses a low-resistance material after heat treatment such as an activation process, a crystallization process, and a gettering process. Wiring such as signal lines and scanning lines is formed. Therefore, a TFT having crystallinity, a small amount of impurity metal elements, and low wiring resistance can be formed. In the liquid crystal display device of the present invention, a pixel electrode can be formed over the insulating film, and the aperture ratio can be increased.

  A TFT formed of a crystalline semiconductor film has a mobility of several tens to 50 times as high as that of an inverted staggered TFT formed of an amorphous semiconductor film. In addition, the source region and the drain region include a catalyst element in addition to the acceptor element or the donor element. For this reason, a source region and a drain region having low contact resistance with the semiconductor region can be formed. As a result, a semiconductor device that requires high-speed operation can be manufactured. Typically, it is possible to manufacture a liquid crystal display device that can display with a high response speed and a high viewing angle as in the OCB mode.

  In addition, a scanning line driver circuit can be formed at the periphery of the liquid crystal display device at the same time as the TFT in the pixel region. Therefore, a miniaturized liquid crystal display device can be manufactured.

  Further, as compared with a TFT formed using an amorphous semiconductor film, a threshold shift is less likely to occur, and variation in TFT characteristics can be reduced. Therefore, display unevenness can be reduced and a highly reliable semiconductor device can be manufactured as compared with a liquid crystal display device using a TFT formed of an amorphous semiconductor film as a switching element. It is.

  Furthermore, the gettering process performed together with the crystallization process also getters the metal element mixed in the semiconductor film in the film formation stage, so that the off-current can be reduced, typically 6 digits. It is possible to form a TFT having the above ON / OFF ratio. By providing such a TFT in a switching element of a liquid crystal display device, contrast can be improved.

  Furthermore, a liquid crystal television having a liquid crystal display device formed by the above manufacturing process can be manufactured at low cost because throughput and yield can be improved.

(Embodiment 1)
Embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below. Note that in structures of the present invention described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and description thereof is not repeated.

  FIG. 28A is a top view illustrating a structure of a display panel according to the present invention. A pixel portion 2701 in which pixels 2702 are arranged in a matrix over a substrate 2700 having an insulating surface, a scanning line side input terminal 2703, a signal A line side input terminal 2704 is formed. The number of pixels may be provided in accordance with various standards. For XGA, 1024 × 768 × 3 (RGB), for UXGA, 1600 × 1200 × 3 (RGB), and for full specification high vision, 1920 × 1080. X3 (RGB) may be used.

  The pixels 2702 are arranged in a matrix by a scan line extending from the scan line side input terminal 2703 and a signal line extending from the signal line side input terminal 2704 intersecting. Each of the pixels 2702 includes a switching element and a pixel electrode connected to the switching element. A typical example of the switching element is a TFT. By connecting the gate electrode side of the TFT to a scanning line and the source or drain side to a signal line, each pixel can be controlled independently by a signal input from the outside. Yes.

    FIG. 28A shows a structure of a display panel in which signals input to the scanning lines and signal lines are controlled by an external driver circuit. As shown in FIG. 29A, a COG (Chip on The driver IC 2751 may be mounted on the substrate 2700 by the Glass method. As another mounting mode, a TAB (Tape Automated Bonding) method as shown in FIG. 29B may be used. The driver IC may be formed on a single crystal semiconductor substrate or may be a circuit in which a TFT is formed on a glass substrate. In FIG. 29, the driver IC 2751 is connected to the FPC 2750.

    In the case where a TFT provided for a pixel is formed using SAS, a scan line driver circuit 3702 can be formed over the substrate 3700 and integrated as shown in FIG. In FIG. 29B, reference numeral 3701 denotes a pixel portion, and the signal line side driver circuit is controlled by an external driver circuit as in FIG. In the case where a TFT provided for a pixel is formed using a polycrystalline (microcrystalline) semiconductor, a single crystal semiconductor, or the like with high mobility, a scan line driver circuit 4702 and a signal line driver circuit 4704 are formed over a glass substrate in FIG. It can also be integrally formed on 4700.

    The present invention relates to an object necessary for manufacturing a display panel such as a conductive layer for forming a wiring layer or an electrode or a mask layer for forming a predetermined pattern (all forms such as a film and a layer depending on its purpose and function). The liquid crystal display device is manufactured by forming at least one or more of them in a desired shape. The present invention includes a conductive layer such as a gate electrode layer, a source electrode layer, and a drain electrode layer, a semiconductor layer, a mask layer, an insulating film, and the like that are formed in a predetermined shape, which constitute a thin film transistor and a liquid crystal display device. It can be applied to other components.

    This embodiment uses a method of forming a mask by a photolithographic process in which a resist is applied and formed on the entire surface of a substrate and pre-baked, and then ultraviolet rays are irradiated through the mask pattern and a resist pattern is formed by development. Yes. Using the resist pattern as a mask pattern, a film existing in a portion where a pattern is to be formed is removed by etching, thereby forming a desired pattern.

    In the present invention, in the patterning step of the formed product, a step of exposing the photosensitive resist or the material containing the photosensitive substance to light is performed. The light used for exposure is not particularly limited, and any one of infrared light, visible light, and ultraviolet light, or a combination thereof can be used. For example, light emitted from an ultraviolet lamp, black light, halogen lamp, metal halide lamp, xenon arc lamp, carbon arc lamp, high pressure sodium lamp, or high pressure mercury lamp may be used. In that case, the lamp light source may be lit and irradiated for a necessary time, or may be irradiated multiple times.

A laser oscillator may be used as a light source used for exposure. As the laser oscillator, a laser oscillator that can oscillate ultraviolet light, visible light, or infrared light can be used. As the laser oscillator, excimer laser oscillators such as KrF, ArF, KrF, XeCl, and Xe, gas laser oscillators such as He, He—Cd, Ar, He—Ne, and HF, YAG, GdVO ₄ , YVO ₄ , YLF, and YAlO Cr crystal such as _{3, Nd, Er, Ho,} Ce, Co, solid-state laser oscillator using a crystal doped with Ti or Tm, can be used GaN, GaAs, GaAlAs, a semiconductor laser oscillator of InGaAsP or the like. In the solid-state laser oscillator, it is preferable to apply the first to fifth harmonics of the fundamental wave.

    Photosensitive materials are roughly divided into negative types and positive types. In the case of the negative type, a chemical reaction occurs in the exposed part, and only the part in which the chemical reaction is caused by the developer is left to form a pattern. In the case of the positive type, a chemical reaction occurs in the exposed portion, the portion in which the chemical reaction has occurred is dissolved by the developing solution, and only the unexposed portion is left to form a pattern. It is good to use a negative type and a positive type as needed.

    In this embodiment, the exposure is performed from the front surface of the substrate, but the exposure may be performed from the back surface of the substrate as necessary.

    An embodiment of the present invention will be described with reference to FIGS. 1 to 6 and FIG. More specifically, a method for manufacturing a liquid crystal display device to which the present invention is applied will be described. First, a method for manufacturing a liquid crystal display device having a channel-etched thin film transistor to which the present invention is applied will be described. 2 to 6A are top views of the pixel portion of the liquid crystal display device, and FIG. 2B to FIG. 6B are cross-sectional views taken along line AB in FIG. 2 to FIG. FIG. 6C is a cross-sectional view taken along line CD in FIGS. 2 to 6A.

    As the substrate 100, a glass substrate made of barium borosilicate glass, alumino borosilicate glass, or the like, a quartz substrate, a silicon substrate, a metal substrate, a stainless steel substrate, or a plastic substrate having heat resistance that can withstand the processing temperature in this manufacturing process is used. Further, polishing may be performed by a CMP method or the like so that the surface of the substrate 100 is planarized. Note that an insulating film may be formed over the substrate 100. The insulating film is formed as a single layer or a stacked layer using an oxide material or a nitride material containing silicon by a known method such as a CVD method, a plasma CVD method, a sputtering method, or a spin coating method. This insulating film is not necessarily formed, but has an effect of blocking contaminants from the substrate 100. As the substrate 100, a large area substrate such as 320 mm × 400 mm, 370 mm × 470 mm, 550 mm × 650 mm, 600 mm × 720 mm, 680 mm × 880 mm, 1000 mm × 1200 mm, 1100 mm × 1250 mm, 1150 mm × 1300 mm can be used.

    A conductive film 101 is formed over the substrate 100. The conductive film 101 is patterned into a gate electrode layer and a pixel electrode layer. The conductive film 101 is preferably formed using a high melting point material by a known method such as a printing method, an electroplating method, a PVD method (Physical Vapor Deposition), a CVD method (Chemical Vapor Deposition), or an evaporation method. By using a high melting point material, a later heating step is possible. High melting point materials include tungsten (W), molybdenum (Mo), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), cobalt (Co) A metal such as nickel (Ni) or platinum (Pt), an alloy thereof, or a metal nitride thereof can be used as appropriate. Further, a plurality of these layers may be stacked. Typically, a tantalum nitride film may be stacked on the substrate surface, and a tungsten film may be stacked thereon. Such a reflective metal is preferable when a reflective liquid crystal display panel is manufactured. Alternatively, a material in which an impurity element imparting one conductivity type is added to silicon may be used. For example, an n-type silicon film in which an amorphous silicon film contains an impurity element imparting n-type such as phosphorus (P) can be used.

Since the conductive film 101 also functions as a pixel electrode layer, the conductive film 101 can be formed using a transparent conductive material. When a transmissive liquid crystal display panel is manufactured, the pixel electrode layer is made of indium tin oxide (ITO), indium tin oxide containing silicon oxide (ITSO), zinc oxide (ZnO), tin oxide (SnO ₂ ). You may form by. Preferably, it is formed of indium tin oxide (ITO), indium tin oxide containing silicon oxide (ITSO), zinc oxide (ZnO), or the like by a sputtering method. More preferably, indium tin oxide containing silicon oxide is used by a sputtering method using a target containing 2 to 10% by weight of silicon oxide in ITO. In addition, a conductive material such as an indium zinc oxide alloy in which silicon oxide is included and indium oxide is mixed with 2 to 20% zinc oxide (ZnO) may be used.

  In this embodiment, the conductive film 101 is formed using indium tin oxide (ITO) as a conductive material by a sputtering method and baked at 550 ° C. Further, the conductive film 101 to be the electrode layer may be formed by stacking a plurality of conductive materials.

  A mask 102a and a mask 102b made of resist are formed over the conductive film 101 using a photolithography process. (See FIG. 2).

  For the mask, a commercially available resist material containing a photosensitizer may be used. For example, a novolak resin that is a typical positive resist and a naphthoquinonediazide compound that is a photosensitizer, a base resin that is a negative resist, diphenylsilanediol In addition, an acid generator or the like may be used. Whichever material is used, the surface tension and viscosity are appropriately adjusted by adjusting the concentration of the solvent or adding a surfactant or the like. In addition, when a conductive material containing a photosensitive substance having photosensitivity is used for the conductive film 101, a desired pattern can be obtained by directly exposing the conductive film 101 without removing a mask made of a resist and performing removal using an etchant. Can be patterned. In this case, there is an advantage that the process is simplified because it is not necessary to form a mask. The conductive material containing a photosensitive substance is a photosensitive material composed of a metal or alloy such as Ag, Au, Cu, Ni, Al, Pt, and an organic polymer resin, a photopolymerization initiator, a photopolymerization monomer, or a solvent. What contains a functional resin may be used. As the organic polymer resin, a novolak resin, an acrylic copolymer, a methacrylic copolymer, a cellulose derivative, a cyclized rubber resin, or the like is used.

    The conductive film 101 is patterned using the mask 102a and the mask 102b that are finely processed in this manner, so that the gate electrode layer 103 and the pixel electrode layer 111 are formed (see FIG. 3).

  Next, a gate insulating film 105a, a gate insulating film 105b, and a gate insulating film 105c are formed over the gate electrode layer 103 and the pixel electrode layer 111 to form a three-layer structure. The thickness of the gate insulating film 105c in contact with the semiconductor layer is preferably 0.1 nm to 10 nm (preferably 1 nm to 3 nm). With such a structure, the gettering efficiency of the metal element in the semiconductor layer is increased, and the adverse effect of the silicon nitride film on the semiconductor layer can be reduced. The insulating films to be stacked are preferably formed continuously at the same temperature without breaking the vacuum in the same chamber while switching the reaction gas. If formed continuously without breaking the vacuum, it is possible to prevent the interface between the stacked films from being contaminated.

The gate insulating film 105a, the gate insulating film 105b, and the gate insulating film 105c are formed of silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy) (x> y), and silicon nitride oxide (SiNxOy) (x> y). ) And the like can be used as appropriate. Further, the gate electrode layer 103 may be anodized to form an anodized film instead of the gate insulating film 105a. Note that in order to prevent diffusion of impurities and the like from the substrate side, the gate insulating film 105a is preferably formed using silicon nitride (SiNx), silicon nitride oxide (SiNxOy) (x> y), or the like. The gate insulating film 105b is preferably formed using silicon oxide (SiOx) or silicon oxynitride (SiOxNy) (x> y). Note that the gate insulating film 105b contains hydrogen. The gate insulating film 105c is preferably formed using a silicon nitride film (SiNx), a silicon nitride oxide film (SiNxOy) (x> y), or the like. Note that in order to form a dense insulating film with low gate leakage current at a low deposition temperature, a rare gas element such as argon is preferably contained in the reaction gas and mixed into the formed insulating film. In this embodiment, a gate insulating film 105a is formed with a silicon nitride film having a thickness of 50 nm to 140 nm using SiH ₄ and NH ₃ as reaction gases, and a silicon oxide film is formed with a film thickness of 100 nm using SiH ₄ and N ₂ O as reaction gases. After stacking the gate insulating film 105b, a silicon nitride film is formed to a thickness of 1 nm to ₃ nm using SiH ₄ and NH ₃ as reaction gases to form a gate insulating film 105c. Note that each of the gate insulating film 105a and the gate insulating film 105b preferably has a thickness of 50 nm to 100 nm. In addition, the gate insulating film 105c may be extremely thin depending on the formation conditions, and the gate insulating film 105c may not be kept in the form of a film.

    Next, a semiconductor film is formed. A detailed method for manufacturing the semiconductor layer will be described with reference to FIGS. The semiconductor film may be formed by a known means (a sputtering method, an LPCVD method, a plasma CVD method, or the like) with a thickness of 25 to 200 nm (preferably 30 to 150 nm). In this embodiment mode, it is preferable to use a crystallized semiconductor film obtained by crystallizing an amorphous semiconductor film.

    As a material for forming the semiconductor film, an amorphous semiconductor (hereinafter also referred to as “amorphous semiconductor: AS”) manufactured by a vapor deposition method or a sputtering method using a semiconductor material gas typified by silane or germane, the non-material is used. A polycrystalline semiconductor obtained by crystallizing a crystalline semiconductor using thermal energy, a semi-amorphous (also referred to as microcrystal or microcrystal, hereinafter, also referred to as “SAS”) semiconductor, or the like can be used.

SAS is a semiconductor having an intermediate structure between amorphous and crystalline structures (including single crystal and polycrystal) and having a third state that is stable in terms of free energy and has a short-range order and a lattice. It includes a crystalline region with strain. A crystal region of 0.5 to 20 nm can be observed in at least a part of the film, and when silicon is the main component, the Raman spectrum shifts to a lower wave number side than 520 cm ^−1. Yes. In X-ray diffraction, diffraction peaks of (111) and (220) that are derived from the silicon crystal lattice are observed. As a neutralizing agent for dangling bonds, hydrogen or halogen is contained at least 1 atomic% or more. The SAS is formed by glow discharge decomposition (plasma CVD) of a silicide gas. As the silicide gas, SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , SiF _{4, and the} like can be used. Further, F ₂ and GeF ₄ may be mixed. This silicide gas may be diluted with H ₂ , or H ₂ and one or more kinds of rare gas elements selected from He, Ar, Kr, and Ne. The dilution rate is in the range of 2 to 1000 times, the pressure is in the range of approximately 0.1 Pa to 133 Pa, and the power supply frequency is 1 MHz to 120 MHz, preferably 13 MHz to 60 MHz. The substrate heating temperature is preferably 300 ° C. or lower, and can be formed even at a substrate heating temperature of 100 to 200 ° C. Here, as an impurity element mainly taken in at the time of film formation, it is desirable that impurities derived from atmospheric components such as oxygen, nitrogen, and carbon be 1 × 10 ²⁰ cm ⁻³ or less, and in particular, the oxygen concentration is 5 × 10 5. It is preferable to be ¹⁹ cm ⁻³ or less, preferably 1 × 10 ¹⁹ cm ⁻³ or less. Further, by adding a rare gas element such as helium, argon, krypton, or neon to further promote lattice distortion, stability is improved and a favorable SAS can be obtained. In addition, a SAS layer formed of a hydrogen-based gas may be stacked on a SAS layer formed of a fluorine-based gas as a semiconductor film.

In order to obtain a semiconductor film having a good crystal structure by subsequent crystallization, the concentration of impurities such as oxygen and nitrogen contained in the amorphous semiconductor film 404 shown in FIG. 8 is set to 5 × 10 ¹⁸ / cm. ³ (Hereinafter, all concentrations are shown as atomic concentrations measured by secondary ion mass spectrometry (SIMS)). These impurities are likely to react with the catalytic element, hinder subsequent crystallization, and increase the density of capture centers and recombination centers even after crystallization.

    In this embodiment mode, a thermal crystallization method using an element that promotes crystallization is used for an amorphous semiconductor film or a SAS film. As a heating method, there are RTA methods such as a GRTA (Gas Rapid Thermal Anneal) method and an LRTA (Lamp Rapid Thermal Anneal) method.

    The method of introducing the metal element into the amorphous semiconductor film is not particularly limited as long as the metal element can be present on the surface of the amorphous semiconductor film or inside the amorphous semiconductor film. For example, sputtering, CVD, Plasma treatment methods (including plasma CVD methods), adsorption methods, metal salt solution coating methods, ion implantation methods, and ion doping methods can be used. Among these, the method using a solution is simple and useful in that the concentration of the metal element can be easily adjusted. At this time, in order to improve the wettability of the surface of the base film on which the metal element film is formed and to spread the aqueous solution over the entire surface of the base film, irradiation with UV light in an oxygen atmosphere, thermal oxidation method, hydroxy radical It is desirable to form an oxide film by treatment with ozone water or hydrogen peroxide.

    In this embodiment mode, a metal film 403 is formed over the gate insulating film 105c by applying Ni as an element for promoting crystallization and applying an aqueous solution containing 10 ppm of Ni in terms of weight by a spin coating method ( (See FIG. 8A.) As elements that promote crystallization, metal elements that promote crystallization of silicon include iron (Fe), nickel (Ni), titanium (Ti), cobalt (Co), ruthenium (Ru), and rhodium (Rh). The metal film 403 may be formed using one or more selected from palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), copper (Cu), and gold (Au). it can. The metal film 403 has an extremely thin film thickness depending on the formation conditions, and does not have to maintain the form as a film. In order to obtain an effect of promoting crystallization, the film may be formed in contact with the amorphous semiconductor film 404 formed in a later step.

An amorphous semiconductor film 404 is formed over the metal film 403. As the amorphous semiconductor film 404, amorphous silicon formed using a reactive gas of SiH ₄ and H ₂ is used. In this embodiment mode, Ni added as a metal element is formed by forming the amorphous semiconductor film 404 with an oxygen concentration of 5 × 10 ¹⁹ atom / cm ³ or less, preferably 2 × 10 ¹⁹ atom / cm ³ or less. Makes gettering easier. The thickness of the amorphous semiconductor film 404 is preferably 30 nm to 150 nm. In this embodiment mode, the amorphous semiconductor film 404 is formed with a thickness of 150 nm.

    When crystallization using a metal element is performed, a gettering step is performed in order to reduce or remove the metal element. After the metal element of the metal film 403 diffuses into the amorphous semiconductor film 404 and contributes to crystallization, a semiconductor film is formed in contact with the amorphous semiconductor film 404 as a layer that sucks the metal element into itself. In this embodiment mode, a metal element is captured using an amorphous semiconductor film having impurities as a gettering sink.

A semiconductor film 405a and a semiconductor film 405b are formed over the amorphous semiconductor film 404 by a plasma CVD method. The semiconductor films 405a and 405b have an impurity element, and an impurity element imparting n-type conductivity, a rare gas element, or the like can be used as the impurity element. For example, phosphorus (P), nitrogen (N), arsenic, or the like can be used. One or more selected from (As), antimony (Sb), bismuth (Bi), helium (He), neon (Ne), argon (Ar), Kr (krypton), and Xe (xenon) may be used. it can. The n-type semiconductor film containing an impurity element imparting n-type conductivity can be formed so as to contain a rare gas element such as argon. In this embodiment mode, the semiconductor film 405a and the semiconductor film 405b contain an impurity element imparting n-type conductivity (phosphorus is used in this embodiment mode). It is formed to be lower than the film 405b. The impurity element may be formed by a CVD method or the like so as to include the impurity element, or may be added by an ion doping method or the like after the semiconductor film is formed. Further, in this embodiment mode, the amorphous semiconductor film 404, the semiconductor film 405a, and the semiconductor film 405b are formed using the reactive gas at the same temperature (330 ° C. in this embodiment) without breaking the vacuum in the same chamber. Form continuously while cutting. After the amorphous semiconductor film 404 is formed, a semiconductor film 405a and a semiconductor film 405b are formed.

    FIG. 37 shows the impurity profile of the semiconductor film containing the impurity element imparting n-type conductivity at this time. FIG. 37A shows a profile 900a of an impurity element imparting n-type when the semiconductor films 901a and 901b containing an impurity element imparting n-type are formed over the crystalline semiconductor film 903 by a plasma CVD method. Show. The semiconductor film 901a and the semiconductor film 901b correspond to the semiconductor film 405a and the semiconductor film 405b. The semiconductor film 901a is formed as an n-type low-concentration impurity region (also referred to as an n− region), and the semiconductor film 901b is an n-type. Is formed as a high concentration impurity region (also referred to as an n + region). Therefore, an impurity element imparting a constant concentration of n-type in the depth direction is distributed in each of the semiconductor film 901a and the semiconductor film 901b, and the semiconductor film 901a has a lower concentration than the semiconductor film 901b. An impurity element imparting n-type is distributed. The semiconductor film 901b which is an n + region later functions as a source region and a drain region, and the semiconductor film 901a which is an n− region functions as an LDD (Lightly Doped Drain) region. Note that an interface exists because the n + region and the n− region are separately formed. The film thickness control of the n + region and the n− region can be achieved by controlling the film thickness of each concentration of semiconductor film.

    As the impurity element imparting p-type conductivity to the semiconductor film 901a and the semiconductor film 901b formed in FIG. 37A, boron is added by an ion doping method or an ion implantation method, so that the p-type when the semiconductor film 911 is formed is imparted. A profile 913 of the impurity element is illustrated in FIG. It can be seen that the concentration of the impurity element imparting p-type is higher than the concentration of the impurity element imparting n-type, and the semiconductor film 911 is a semiconductor film having p-type. Further, the impurity element imparting p-type conductivity is added to the crystalline semiconductor film 903 because it is channel-doped. As shown in FIG. 38A, the vicinity of the surface of the semiconductor film 911 is a p-type impurity region (also referred to as a p + region) 912b having a relatively high concentration of an impurity element imparting p-type, As the crystalline semiconductor film 903 is approached, the concentration of the impurity element imparting p-type is relatively reduced, and a p-type low-concentration impurity region (also referred to as p-region) 912a is formed.

On the other hand, in FIG. 37B, a semiconductor film having a state selected from an amorphous semiconductor, a SAS, a microcrystalline semiconductor, and a crystalline semiconductor is formed over the crystalline semiconductor film 903; A profile 900b of an impurity element imparting n-type when the semiconductor film 902 is formed by adding an impurity element imparting n-type to the semiconductor film by an ion doping method or an ion implantation method is shown. As shown in FIG. 37B, the concentration of an impurity element imparting n-type conductivity is relatively high in the vicinity of the surface of the semiconductor film 902. A region where the concentration of an impurity element imparting n-type conductivity is 1 × 10 ¹⁹ / cm ³ or more is referred to as an n-type high-concentration impurity region (also referred to as an n + region) 904b. On the other hand, as the crystalline semiconductor film 903 is approached, the concentration of the impurity element imparting n-type decreases relatively. A region where the concentration of an impurity element imparting n-type conductivity is 5 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ is referred to as an n-type low-concentration impurity region (also referred to as an n− region) 904a. The n + region 904b functions as a source region and a drain region later, and the n− region 904a functions as an LDD region. Note that the interface between the n + region and the n− region does not exist, and changes depending on the concentration of the impurity element that imparts a relative n-type. In this manner, the semiconductor film 902 including the impurity element imparting n-type formed by the ion doping method or the ion implantation method can control the concentration profile depending on the addition conditions, and the n + region and the n− region The film thickness can be appropriately controlled. By having the n + region and the n− region, the effect of relaxing the electric field is increased, and a thin film transistor with improved hot carrier resistance can be formed.

    Profile of the impurity element imparting p-type when boron is added to the semiconductor film 902 formed in FIG. 37B as an impurity element imparting p-type by an ion doping method or an ion implantation method. 923 is shown in FIG. The concentration of the impurity element imparting p-type is higher than the concentration of the impurity element imparting n-type, and the semiconductor film 921 is a p-type semiconductor film (also referred to as a semiconductor film having a p-type impurity region). I can see that Further, the impurity element imparting p-type conductivity is added to the crystalline semiconductor film 903 because it is channel-doped. As shown in FIG. 38B, the vicinity of the surface of the semiconductor film 921 is a p-type impurity region (also referred to as a p + region) 922b having a relatively high concentration of an impurity element imparting p-type conductivity, As the crystalline semiconductor film 903 is approached, the concentration of the impurity element imparting p-type is relatively reduced, and a p-type low-concentration impurity region (also referred to as p-region) 922a is formed. Further, in the step of adding an impurity element imparting n-type, the impurity element concentration on the film surface may be high depending on the addition conditions. In such a case, a process of adding an impurity element imparting p-type may be performed after the film surface is thinly etched and the film in the high impurity element concentration region is removed.

In this embodiment, as the semiconductor film 405a and the semiconductor film 405b, an n-type semiconductor film containing phosphorus which is an impurity element imparting n-type (a donor element) is formed by a plasma CVD method. Further, since the concentration of the impurity element imparting n-type included in the semiconductor films 405a and 405b is different, the semiconductor film 405a becomes an n-type low-concentration impurity region, and the semiconductor film 405b has an n-type high concentration. It is an impurity region. The impurity concentration of the n-type low-concentration impurity region is 1 × 10 ^{17 to} 3 × 10 ¹⁹ / cm ³ , preferably 1 × 10 ¹⁸ to 1 × 10 ¹⁹ / cm ³ , and the impurity concentration of the n-type high-concentration impurity region Is preferably 10 to 100 times, and can be 1 × 10 ^{19 to} 3 × 10 ²¹ / cm ³ . The thickness of the semiconductor film 405a which is an n-type low concentration impurity region is 20 to 200 nm, typically 50 to 150 nm. In this embodiment, the semiconductor film 405a is formed with a thickness of 50 nm. The thickness of the semiconductor film 405b which is an n-type high concentration impurity region is 30 to 100 nm, typically 40 to 60 nm. In this embodiment, the semiconductor film 405b is formed with a thickness of 50 nm.

After that, heat treatment is performed, and the amorphous semiconductor film is crystallized to form the crystalline semiconductor film 406, and a gettering step is simultaneously performed to reduce or remove the metal element in the crystalline semiconductor film 406. In this case, in crystallization, silicide is formed in a portion of the semiconductor film in contact with a metal element that promotes crystallization of the semiconductor, and crystallization proceeds using the silicide as a nucleus. Here, after the heat treatment for dehydrogenation, heat treatment for crystallization and gettering steps (550 ° C. to 650 ° C. for 5 minutes to 24 hours) is performed. Further, the crystallization and gettering steps may be performed by RTA or GRTA. Here, by performing crystallization without laser light irradiation for heating, variation in crystallinity can be reduced, and variation in TFTs to be formed later can be suppressed. In this embodiment mode, since the amorphous semiconductor film containing impurities is formed in contact with the crystalline semiconductor film 406 as a gettering sink, the metal element is an arrow as shown in FIG. And is trapped in the semiconductor film 405a and the semiconductor film 405b. The semiconductor films 405a and 405b become a semiconductor film 408a and a semiconductor film 408b containing a metal element. In this embodiment, the semiconductor film 408a and the semiconductor film 408b include an impurity element imparting n-type conductivity and a metal element that promotes crystallization. Through this step, the concentration at which the element that promotes crystallization in the crystalline semiconductor film 406 (in this embodiment, nickel element) does not affect the device characteristics, that is, the nickel concentration in the film is 1 × 10 ¹⁸ / cm ^3. Hereinafter, it can be desirably 1 × 10 ¹⁷ / cm ³ or less. In addition, the semiconductor film 408a and the semiconductor film 408b to which the metal catalyst after gettering has moved may be crystallized by heat treatment. Note that in this embodiment, an impurity element imparting n-type conductivity (a donor element) in the semiconductor film 408a and the semiconductor film 408b is activated together with the gettering step. The heat treatment may be performed in a nitrogen atmosphere. In this embodiment, the heat treatment is performed at 550 ° C. for 4 hours, but the heat treatment may be performed at 650 ° C. for 6 minutes by the RTA method.

The crystalline semiconductor film 406 thus obtained may be doped with a trace amount of an impurity element (boron or phosphorus) in order to control the threshold voltage of the thin film transistor. This doping of the impurity element may be performed on the amorphous semiconductor film before the crystallization process, or may be performed after the metal element in the crystalline semiconductor film 406 is reduced and removed by the gettering process. In this embodiment mode, boron is added by an ion doping method in which diborane (B ₂ H ₆ ) is plasma-excited without mass separation. Note that an ion implantation method in which mass separation is performed may be used. When the impurity element is doped in the state of the amorphous semiconductor film, the impurity can be activated by heat treatment for subsequent crystallization. In addition, defects and the like generated during doping can be improved.

    Next, a resist mask is formed over the crystalline semiconductor film 406, the semiconductor film 408a, and the semiconductor film 408b using a photolithography process, and the crystalline semiconductor film 406, the semiconductor film 408a, and the semiconductor are formed using the finely processed mask. The film 408b is patterned to form the crystalline semiconductor layer 106, the semiconductor layer 107a, and the semiconductor layer 107b. In this embodiment mode, a photomask is manufactured, and a crystalline semiconductor layer 106, an n-type semiconductor layer 107a, and an n-type semiconductor layer 107b are formed by patterning treatment using a photolithography method (see FIG. 4). .) As for the photomask, a mask with a fine pattern may be formed by a photolithography process in the same manner as when the mask 102a is formed. The semiconductor film can be finely and finely patterned into a desired shape with a fine pattern mask.

As the etching process at the time of patterning, either plasma etching (dry etching) or wet etching may be employed, but plasma etching is suitable for processing a large area substrate. As an etching gas, a fluorine-based gas such as CF ₄ , NF ₃ , SF ₆ , or CHF ₃ , a chlorine-based gas typified by Cl ₂ , BCl ₃ , SiCl _4, CCl _4, or the like, or an O ₂ gas is used. An inert gas such as Ar or Ar may be added as appropriate. Further, if an atmospheric pressure discharge etching process is applied, a local electric discharge process is also possible, and it is not necessary to form a mask layer on the entire surface of the substrate.

In the photolithography processes of the following embodiments and examples, it is preferable to form an insulating film having a thickness of several nanometers on the surface of the semiconductor film before applying the resist. By this step, it is possible to avoid direct contact between the semiconductor film and the resist, and impurities can be prevented from entering the semiconductor film. Note that examples of a method for forming the insulating film include a method of applying an oxidizing solution such as ozone water, a method of irradiating oxygen plasma, ozone plasma, and the like.

  Next, a conductive film is formed by a sputtering method, and a resist mask is formed over the conductive film using a photolithography process. A source or drain electrode layer 130, a source or drain electrode layer 108, and a capacitor wiring layer 104 are formed using a mask, and the source or drain electrode layer 130 and the source or drain electrode layer 108 are formed. As a mask, the crystalline semiconductor layer 106, the n-type semiconductor layer 107a, and the n-type semiconductor layer 107b are patterned, so that the semiconductor layer 115, the n-type semiconductor layer 116a, the n-type semiconductor layer 116b, An n-type semiconductor layer 117a and an n-type semiconductor layer 117b are formed (see FIG. 5). The step of forming the source or drain electrode layer 130 and the source or drain electrode layer 108 can also be formed in the same manner as the gate electrode layer 103 is formed. The source or drain electrode layer 130 also functions as a wiring layer.

  As a conductive material for forming the source or drain electrode layer 130 and the source or drain electrode layer 108, Ag (silver), Au (gold), Cu (copper), W (tungsten), Al (aluminum) The metal which has the main component etc. can be used. Further, light-transmitting indium tin oxide (ITO), ITSO made of indium tin oxide and silicon oxide, organic indium, organic tin, zinc oxide, titanium nitride, or the like may be combined.

  A method for forming the source electrode layer or the drain electrode layer will be described. The source or drain electrode layer 130 and the source or drain electrode layer 108 are formed in a fine pattern, and if not formed with good controllability, a defect such as a short circuit due to poor formation is caused. Therefore, in this embodiment mode, fine patterning on the semiconductor layer is performed by forming a photomask and performing patterning using a photolithography method. As shown in FIG. 4, a gate electrode layer, a gate insulating film, a semiconductor layer, and an n-type semiconductor layer are formed over a substrate, and a conductive film is formed over the entire surface so as to cover them. The conductive film can be formed by an evaporation method, a CVD method, a sputtering method, or the like. Thereafter, a resist mask is formed. The resist mask is exposed to light and exposed to light. Since a positive photosensitive resist is used in this embodiment mode, an exposed region is removed by an etchant, so that an opening is formed. By patterning the conductive film by etching using a mask having an opening, the source or drain electrode layer 130 and the source or drain electrode layer 108 are formed.

    An insulating film 109 serving as a passivation film is preferably formed so as to cover the source or drain electrode layer, the semiconductor layer, the gate electrode layer, and the gate insulating film. The insulating film 109 is formed using a thin film formation method such as a plasma CVD method or a sputtering method, and contains silicon nitride, silicon oxide, silicon nitride oxide, silicon oxynitride, aluminum oxynitride, or aluminum oxide, diamond-like carbon (DLC), and nitrogen. It can be formed using carbon (CN) or other insulating materials. Note that the passivation film may be a single layer or a laminated structure. Here, a stacked structure in which silicon oxide or silicon oxynitride is formed from the interface characteristics of the semiconductor layer 115 and then silicon nitride or silicon nitride oxide is formed to prevent external impurities from entering the semiconductor element. preferable. In this embodiment mode, after forming a silicon oxide film with a thickness of 150 nm in contact with the semiconductor layer 115, the insulating film 109 has a stacked structure in which a gas is switched in the same chamber to continuously form a silicon nitride film with a thickness of 200 nm. Form.

    Thereafter, the semiconductor layer 115 is preferably hydrogenated by heating in a hydrogen atmosphere or a nitrogen atmosphere. Note that in the case of heating in a nitrogen atmosphere, an insulating film containing hydrogen is preferably formed as the insulating film 109.

    Next, the insulating film 110 is formed. In this embodiment mode, the insulating film 110 is formed over the entire surface, and is etched and patterned using a mask such as a resist.

    The insulating film 110 includes silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, diamond-like carbon (DLC), nitrogen-containing carbon film (CN), other inorganic insulating materials, or acrylic acid, Methacrylic acid and derivatives thereof, silicon, oxygen formed using organic insulating materials such as polyimide, aromatic polyamide, polybenzimidazole, benzocyclobutene, polysilazane, or siloxane-based materials as starting materials Among the compounds composed of hydrogen, inorganic siloxanes containing Si—O—Si bonds, and organic siloxane insulating materials in which hydrogen on silicon is replaced by organic groups such as methyl and phenyl can be used. You may form using photosensitive and non-photosensitive materials, such as an acryl and a polyimide.

    In this embodiment, as a material of the insulating film 110, a skeleton structure is formed by a bond of silicon (Si) and oxygen (O), and a substituent includes hydrogen, fluorine, an alkyl group, or an aromatic hydrocarbon. A coating film using a material having at least one kind is used. The fired film can also be called a silicon oxide film (SiOx) containing an alkyl group.

    An opening 135 reaching the source electrode layer or the drain electrode layer 108 in the insulating film 109 and the insulating film 110, and a pixel electrode layer in the gate insulating film 105 a, the gate insulating film 105 b, the gate insulating film 105 c, the insulating film 109, and the insulating film 110 An opening 136 reaching 111 and an opening 137 reaching the gate electrode layer 103 are formed. This opening is also formed by etching using a resist mask. A mask used for patterning is formed using a photolithography process. A wiring layer 113 is formed in the opening 135 and the opening 137 thus formed, and the source or drain electrode layer 108 and the pixel electrode layer 111 are electrically connected. The gate wiring layer 112 is also formed in the opening 137 so as to be electrically connected to the gate electrode layer 103. By forming the gate wiring layer 112 with a low-resistance material, even when the gate electrode layer 103 is a material with a relatively high resistance, high-speed operation is possible and a large current can flow.

    Through the above steps, a TFT substrate for a liquid crystal display panel in which a bottom gate type (also referred to as an inverted stagger type) thin film transistor and a pixel electrode are connected to the substrate 100 is completed (see FIG. 6). The thin film transistor of this embodiment is a channel etch type.

    Next, as illustrated in FIG. 1, an insulating film 114 called an alignment film is formed by a printing method or a spin coating method so as to cover the pixel electrode layer 111. FIG. 1 is a cross-sectional view taken along line AB of the top view shown in FIGS. Note that the insulating film 114 can be selectively formed by a screen printing method or an offset printing method. Then, rubbing is performed. Subsequently, a sealing material is formed in a peripheral region where pixels are formed by a droplet discharge method (not shown).

  After that, the insulating film 121 functioning as an alignment film, the colored layer 122 functioning as a color filter, the conductor layer 123 functioning as a counter electrode, the counter substrate 124 provided with the polarizing plate 125a, and the substrate 100 having TFTs are provided with spacers. And a liquid crystal display panel can be manufactured by providing the liquid crystal layer 120 in the gap (see FIG. 1). The substrate 100 is also provided with a polarizing plate 125b on the surface opposite to the surface having TFTs. A filler may be mixed in the sealing material, and a shielding film (black matrix) or the like may be formed on the counter substrate 124. Note that as a method of forming the liquid crystal layer, a dispenser type (dropping type) or a dip type (pumping type) in which liquid crystal is injected by using a capillary phenomenon after the counter substrate 124 is attached can be used.

  A liquid crystal dropping injection method employing a dispenser method will be described with reference to FIG. In FIG. 22, 40 is a control device, 42 is an imaging means, 43 is a head, 33 is a liquid crystal, 35 and 41 are markers, 34 is a barrier layer, 32 is a sealing material, 30 is a TFT substrate, and 20 is a counter substrate. A closed loop is formed by the sealing material 32, and the liquid crystal 33 is dropped from the head 43 once or plural times therein. The head 43 includes a plurality of nozzles, and a large amount of liquid crystal material can be dropped at a time, thereby improving the throughput. At that time, a barrier layer 34 is provided to prevent the sealing material 32 and the liquid crystal 33 from reacting. Subsequently, the substrates are bonded together in a vacuum, and thereafter UV curing is performed to fill the liquid crystal.

A connection portion is formed in order to connect the pixel portion formed in the above steps and an external wiring substrate. The insulator layer in the connection portion is removed by ashing using oxygen gas at or near atmospheric pressure. This treatment is performed using oxygen gas and one or more selected from hydrogen, CF ₄ , NF ₃ , H ₂ O, and CHF ₃ . In this step, in order to prevent damage and destruction due to static electricity, ashing is performed after sealing using the counter substrate. However, if there is little influence from static electricity, it may be performed at any timing. .

  Subsequently, a wiring board for connection is provided so that the wiring layer in the liquid crystal display device is electrically connected via the anisotropic conductor layer. The wiring board plays a role of transmitting signals and potentials from the outside, and an FPC (Flexible printed circuit) or the like can be used. Through the above steps, a liquid crystal display panel including a channel etch type switching TFT and a capacitor is completed. The capacitor is formed of the capacitor wiring layer 104, the gate insulating film 105a, the gate insulating film 105b, the gate insulating film 105c, and the pixel electrode layer 111.

    The wiring layer in the liquid crystal display device and the FPC are connected using a terminal electrode layer. The terminal electrode layer is made of the same material and process as the gate electrode layer, and the same material and the same material as the source wiring layer that also serves as the source electrode layer and the drain electrode layer. The process and the gate wiring layer can be manufactured in the same material and the same process. A connection example between the FPC and a wiring layer in the liquid crystal display device will be described with reference to FIG.

    In FIG. 42, a thin film transistor 9 and a pixel electrode layer 6 are formed on a substrate 1 and bonded to a counter substrate 8 with a sealing material 3. The wiring layer extending from the inside of the liquid crystal display device and formed outside the sealing material and the FPC 2b and FPC 2a are bonded by the anisotropic conductive film 7a and the anisotropic conductive film 7b.

    42 (A1), (B1), and (C1) are top views of the liquid crystal display device, and FIGS. 42 (A2), (B2), and (C2) are FIGS. 42 (A1), (B1), and (C1). It is sectional drawing of line OP and line RQ in FIG. 42A1 and 42A2, the terminal electrode layer 5a and the terminal electrode layer 5b are formed using the same material and the same process as the gate electrode layer. A source wiring layer 4a formed to extend to the outside of the sealing material is connected to the terminal electrode layer 5a, and the terminal electrode layer 5a and the FPC 2a are connected via an anisotropic conductive film 7a. On the other hand, a gate wiring layer 4b formed to extend to the outside of the sealing material is connected to the terminal electrode layer 5b, and the terminal electrode layer 5b and the FPC 2b are connected via an anisotropic conductive film 7b.

    42B and 42B, the terminal electrode layer 55a and the terminal electrode layer 55b are formed using the same material and the same process as the source wiring layer. The terminal electrode layer 55a is formed of a source wiring layer formed to extend outside the sealing material, and the terminal electrode layer 55a and the FPC 2a are connected via an anisotropic conductive film 7a. On the other hand, a gate wiring layer 54b formed to extend to the outside of the sealing material is connected to the terminal electrode layer 55b, and the terminal electrode layer 55b and the FPC 2b are connected via an anisotropic conductive film 7b.

    42 (C1) and 42 (C2), the terminal electrode layer 64a and the terminal electrode layer 64b are formed of the same material and process as the gate wiring layer. A terminal electrode layer 64a is connected to a source wiring layer 65a formed to extend outside the sealing material, and the terminal electrode layer 64a and the FPC 2a are connected via an anisotropic conductive film 7a. On the other hand, the terminal electrode layer 64b is formed of a gate wiring layer formed to extend outside the sealing material, and the terminal electrode layer 64b and the FPC 2b are connected via an anisotropic conductive film 7b.

  In this embodiment mode, the switching TFT has a single gate structure, but a multi-gate structure such as a double gate structure may be used.

Through the above steps, an inverted staggered thin film transistor having a crystalline semiconductor film can be formed. Since the thin film transistor formed in this embodiment is formed using a crystalline semiconductor film, it has higher mobility (about ^{2 to} 50 cm ² / Vsec) than a thin film transistor formed using an amorphous semiconductor film. In addition, the source region and the drain region include a metal element in addition to the impurity element imparting one conductivity type. For this reason, a source region and a drain region with low resistivity can be formed. As a result, a liquid crystal display device that requires high-speed operation can be manufactured. Therefore, it is possible to manufacture a liquid crystal display device that can display with a high response speed and a high viewing angle as in the OCB mode.

  Further, compared to a thin film transistor formed using an amorphous semiconductor film, threshold shift is less likely to occur, and variations in thin film transistor characteristics can be reduced.

  Further, by simultaneously performing the crystallization of the amorphous semiconductor film and the gettering process, the process can be shortened.

  Further, since the metal element mixed in the semiconductor film in the film formation stage is also gettered by the gettering step, off current can be reduced. For this reason, it is possible to improve contrast by providing such a TFT in a switching element of a liquid crystal display device.

(Embodiment 2)
An embodiment of the present invention will be described with reference to FIG. This embodiment is an example in which the formation position of the metal film is different from that in the first embodiment. Therefore, repetitive description of the same portion or a portion having a similar function is omitted.

    A gate electrode layer 701 is formed over the substrate 700, and a gate insulating film 702a, a gate insulating film 702b, and a gate insulating film 702c are formed so as to cover the gate electrode layer 701. An amorphous semiconductor film 703 is formed over the gate insulating film 702c, and a metal film 704 having an element that promotes crystallization is formed (see FIG. 9A). Next, a semiconductor film 705a and a semiconductor film 705b having impurities are formed over the metal film 704 (see FIG. 9B). In this embodiment, as the semiconductor film 705a and the semiconductor film 705b, an n-type semiconductor film containing phosphorus which is an impurity element imparting n-type (a donor element) is formed by a plasma CVD method. Further, the semiconductor film 705a is provided with a low concentration impurity and later functions as an LDD region, and the semiconductor film 705b is provided with a high concentration impurity and later functions as a source region and a drain region.

After that, by heat treatment, the amorphous semiconductor film 703 is crystallized to form the crystalline semiconductor film 706, and a gettering step is simultaneously performed in order to reduce or remove the metal element in the crystalline semiconductor film 706. In this embodiment mode, an amorphous semiconductor film containing an impurity is formed in contact with the crystalline semiconductor film 706 as a gettering sink, so that the metal element is subjected to heat treatment as illustrated in FIG. The semiconductor film 705a and the semiconductor film 705b are captured by the heat treatment in the direction of the arrow. The semiconductor films 705a and 705b become a semiconductor film 707a and a semiconductor film 707b containing a metal element. In this embodiment, the semiconductor films 707a and 707b include an impurity element imparting n-type conductivity and a metal element that promotes crystallization.

    Next, the crystalline semiconductor film 706, the semiconductor film 707a, and the semiconductor film 707b are patterned using a photolithography process, so that the crystalline semiconductor layer 708, the semiconductor layer 709a, and the semiconductor layer 709b are formed. After that, a conductive film 710 is formed over the semiconductor layer 709b, and a resist mask 711a and a mask 711b are formed using a photolithography process (see FIG. 9D). The conductive film 710 is patterned through the masks 711a and 711b, so that the source or drain electrode layer 712a and the source or drain electrode layer 712b are formed.

    The n-type semiconductor film and the crystalline semiconductor film are etched using the source or drain electrode layer 712a and the source or drain electrode layer 712b as masks, so that the n-type functioning as the semiconductor layer 713 and the source or drain region is formed. The semiconductor layer 714b, the semiconductor layer 715b, the n-type semiconductor layer 714a functioning as the LDD, and the semiconductor layer 715a are formed (see FIG. 9E).

    Through the above steps, gettering of a crystalline semiconductor film crystallized with a metal element can be performed at the same time, and a thin film transistor having a semiconductor layer with reduced metal elements can be formed.

    This embodiment can be used in combination with Embodiment 1.

(Embodiment 3)
An embodiment of the present invention will be described with reference to FIG. This embodiment is an example of the liquid crystal display device including the channel protective thin film transistor in Embodiment 1. Therefore, repetitive description of the same portion or a portion having a similar function is omitted.

    A gate electrode layer 721 is formed over the substrate 720, and a gate insulating film 722a, a gate insulating film 722b, and a gate insulating film 722c are formed so as to cover the gate electrode layer 721. A metal film 723 including an element that promotes crystallization is formed over the gate insulating film 722c, so that an amorphous semiconductor film 724 is formed (see FIG. 10A). A channel protective film is formed over the amorphous semiconductor film 724, and the channel protective film is patterned using a photolithography process, so that a channel protective layer 725 is formed. As the channel protective film, silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy) (x> y), silicon nitride oxide (SiNxOy) (x> y), or the like can be used as appropriate. By forming the channel protective layer 725, etching of the semiconductor layer in the channel portion can be prevented when the source electrode layer and the drain electrode layer are formed. In this embodiment, silicon nitride is formed on the channel protective film to form the channel protective layer 725 (see FIG. 10B).

  Next, a semiconductor film 726a and a semiconductor film 726b having impurities are formed (see FIG. 10C). In this embodiment, as the semiconductor film 726a and the semiconductor film 726b, an n-type semiconductor film containing phosphorus which is an impurity element imparting n-type (donor type element) is formed by a plasma CVD method. In addition, the semiconductor film 726a is provided with a low concentration impurity and later functions as an LDD region, and the semiconductor film 726b is provided with a high concentration impurity and functions later as a source region and a drain region.

  After that, by heat treatment, the amorphous semiconductor film is crystallized to form the crystalline semiconductor film 727 and a gettering step for reducing or removing the metal element in the crystalline semiconductor film 727 is performed at the same time. In this embodiment mode, an amorphous semiconductor film having an impurity is formed in contact with the crystalline semiconductor film 727 as a gettering sink, so that the metal element is subjected to heat treatment as illustrated in FIG. It moves by the heat treatment in the direction of the arrow and is trapped in the semiconductor film 726a and the semiconductor film 726b. The semiconductor films 726a and 726b are a semiconductor film 728a and a semiconductor film 728b containing a metal element. In this embodiment, the semiconductor film 728a and the semiconductor film 728b include an impurity element imparting n-type conductivity and a metal element that promotes crystallization.

    Next, the crystalline semiconductor film 727, the semiconductor film 728a, and the semiconductor film 728b are formed using a resist mask by a photolithography process and patterned using the mask, so that the crystalline semiconductor layer 729, the semiconductor layer 730a, and the semiconductor layer 730b are formed. Form. After that, a conductive film 731 is formed over the semiconductor layer 730b, and a resist mask 732a and a mask 732b are formed using a photolithography process (see FIG. 10E). The conductive film 731 is patterned through the masks 732a and 732b, so that the source or drain electrode layer 733a and the source or drain electrode layer 733b are formed.

    An n-type semiconductor film is etched using the source or drain electrode layer 733a and the source or drain electrode layer 733b as a mask, and an n-type semiconductor layer 735b and a semiconductor layer 736b functioning as a source or drain region, An n-type semiconductor layer 735a and a semiconductor layer 736a functioning as an LDD are formed (see FIG. 10F).

    Through the above process, a thin film transistor in which the semiconductor layer in the channel portion is not etched can be manufactured. In addition, by performing gettering of a crystalline semiconductor film crystallized with a metal element at the same time, a process can be shortened and a thin film transistor having a semiconductor layer with reduced metal element can be formed.

  After that, a TFT substrate for a liquid crystal display panel in which a bottom gate type (also referred to as an inverted stagger type) thin film transistor and a pixel electrode are connected to the substrate 720 is completed by the same process as in Embodiment Mode 1 (FIG. 7). reference). Note that the thin film transistor of this embodiment is a channel protection type.

(Embodiment 4)
An embodiment of the present invention will be described with reference to FIG. This embodiment is an example of a liquid crystal display device including channel protective thin film transistors in Embodiment 2. Therefore, repetitive description of the same portion or a portion having a similar function is omitted.

    A gate electrode layer 741 is formed over the substrate 740, and a gate insulating film 742a, a gate insulating film 742b, and a gate insulating film 742c are formed so as to cover the gate electrode layer 741. An amorphous semiconductor film 743 is formed over the gate insulating film 742c, and a metal film 744 having an element that promotes crystallization is formed (see FIG. 11A). A channel protective film is formed over the amorphous semiconductor film 743, and the channel protective film is patterned using a photolithography process, so that a channel protective layer 745 is formed. As the channel protective film, silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy) (x> y), silicon nitride oxide (SiNxOy) (x> y), or the like can be used as appropriate. By forming the channel protective layer 745, etching of the semiconductor layer in the channel portion can be prevented when the source electrode layer and the drain electrode layer are formed. In this embodiment, silicon nitride is formed as a channel protective film to form a channel protective layer 745 (see FIG. 11B).

  Next, a semiconductor film 746a and a semiconductor film 746b having impurities are formed (see FIG. 11C). In this embodiment, as the semiconductor film 746a and the semiconductor film 746b, an n-type semiconductor film containing phosphorus which is an impurity element imparting n-type (donor type element) is formed by a plasma CVD method. The semiconductor film 746a is added with a low concentration impurity and functions later as an LDD region, and the semiconductor film 746b is added with a high concentration impurity and functions as a source region and a drain region later.

  After that, by heat treatment, the amorphous semiconductor film is crystallized to form the crystalline semiconductor film 747 and a gettering step for reducing or removing the metal element in the crystalline semiconductor film 747 is performed at the same time. In this embodiment mode, an amorphous semiconductor film having an impurity is formed in contact with the crystalline semiconductor film 747 as a gettering sink, so that the metal element is formed by heat treatment as illustrated in FIG. It moves by heat treatment in the direction of the arrow and is trapped in the semiconductor film 746a and the semiconductor film 746b. The semiconductor films 746a and 746b become a semiconductor film 748a and a semiconductor film 748b containing a metal element. In this embodiment, the semiconductor films 748a and 748b include an impurity element imparting n-type conductivity and a metal element that promotes crystallization.

    Next, the crystalline semiconductor film 747, the semiconductor film 748a, and the semiconductor film 748b are formed using a resist mask by a photolithography process and patterned using the mask, so that the crystalline semiconductor layer 749, the semiconductor layer 750a, and the semiconductor layer 750b are formed. Form. After that, a conductive film 751 is formed over the semiconductor layer 750b, and a resist mask 752a and a mask 752b are formed using a photolithography process (see FIG. 11E). The conductive film 751 is patterned through the mask 752a and the mask 752b, so that the source or drain electrode layer 753a and the source or drain electrode layer 753b are formed.

    An n-type semiconductor film is etched using the source or drain electrode layer 753a and the source or drain electrode layer 753b as a mask, and an n-type semiconductor layer 755b and a semiconductor layer 756b functioning as a source or drain region, An n-type semiconductor layer 755a and a semiconductor layer 756a functioning as an LDD are formed (see FIG. 11F).

    Through the above process, a thin film transistor in which a channel portion is not etched can be manufactured. In addition, by performing gettering of a crystalline semiconductor film crystallized with a metal element at the same time, a thin film transistor having a semiconductor layer with reduced metal element can be formed.

  Thereafter, a TFT substrate for a liquid crystal display panel in which a bottom gate type (also referred to as an inverted stagger type) thin film transistor and a pixel electrode are connected to the substrate 740 is completed by the same process as that in Embodiment Mode 1 (FIG. 7). reference). Further, the thin film transistor of this embodiment is a channel protection type.

(Embodiment 5)
An embodiment of the present invention will be described with reference to FIG. This embodiment is an example in which the gettering process of the crystalline semiconductor film is different from that in Embodiment 1. Therefore, repetitive description of the same portion or a portion having a similar function is omitted.

    A gate electrode layer 761 is formed over the substrate 760, and a gate insulating film 762a and a gate insulating film 762b are formed so as to cover the gate electrode layer 761. Note that as illustrated in FIG. 12, a thin gate insulating film is formed over the gate insulating film 762b, and the gate insulating layer has a three-layer structure. A metal film 763 is formed over the gate insulating film 762b, and an amorphous semiconductor film 764 is formed (see FIG. 12A). As a gettering layer for gettering a metal element for promoting crystallization, a semiconductor layer 765 including a rare gas element as an impurity element is formed (see FIG. 12B). As the rare gas element, helium, argon, xenon, krypton, or the like can be used. In this embodiment, a semiconductor film containing argon as an impurity element is formed.

  After that, the amorphous semiconductor film 764 is crystallized by heat treatment to form the crystalline semiconductor film 766. At the same time, the metal element contained in the crystalline semiconductor film 766 moves in the direction of the arrow in FIG. The semiconductor film 765 is captured in the film 765 and becomes a semiconductor film 775 containing a metal element. Accordingly, a crystalline semiconductor film 766 with reduced metal elements contained in the film is formed. Then, the semiconductor film 775 serving as the gettering sink and the oxide film formed over the semiconductor film 775 are removed with hydrofluoric acid or the like, so that the crystalline semiconductor film 766 from which the metal element is reduced or removed can be obtained. it can. In this embodiment mode, the semiconductor film 775 serving as a gettering sink is removed using TMAH (Tetramethyl ammonium hydroxide). A semiconductor film 767 having one conductivity type is formed over the crystalline semiconductor film 766 as shown in FIG. 12D, and a mask made of a resist is formed using the photolithography process for the crystalline semiconductor film 766 and the semiconductor film 767. Then, patterning is performed using a mask to form a crystalline semiconductor layer 768 and a semiconductor layer 769. Note that in this embodiment, a semiconductor film having n-type conductivity is formed as the semiconductor film 767 having one conductivity type. After that, a conductive film 770 is formed over the semiconductor layer 769 and patterned using a resist mask 771a and a mask 771b using a photolithography process, and then a source or drain electrode layer 772a, a source or drain electrode layer 772b. (See FIG. 12E).

    The n-type semiconductor film and the crystalline semiconductor film are etched using the source or drain electrode layer 772a and the source or drain electrode layer 772b as masks, and the n-type functioning as the semiconductor layer 773 and the source or drain region is formed. A semiconductor layer 774a and an n-type semiconductor layer 774b are formed (see FIG. 12F).

    Through the above steps, a crystalline semiconductor film crystallized with a metal element is simultaneously gettered to have a semiconductor layer with reduced metal elements and one conductivity type that functions as a source region or a drain region. A thin film transistor containing no metal element can be formed in the semiconductor layer.

    This embodiment can be used in combination with Embodiment 1.

(Embodiment 6)
An embodiment of the present invention will be described with reference to FIG. This embodiment is an example of manufacturing two types of thin film transistors: an n-channel thin film transistor and a p-channel thin film transistor. Therefore, repetitive description of the same portion or a portion having a similar function is omitted.

  A gate electrode layer 431a and a gate electrode layer 431b are formed over the substrate 430, and a gate insulating film 432a and a gate insulating film 432b are formed. Note that as illustrated in FIG. 13, a thin gate insulating film is formed over the gate insulating film 432b, and the gate insulating layer has a three-layer structure. A metal film 433 is formed over the gate insulating film 432b. After the amorphous semiconductor film 434 is formed over the metal film 433 and the n-type semiconductor film 435 is formed, heat treatment is performed. (See FIG. 13A.)

  By the heat treatment, the amorphous semiconductor film is crystallized to form the crystalline semiconductor film, and at the same time, the metal element contained in the crystalline semiconductor film is gettered and moves in the direction of the arrow to have the n-type semiconductor. A crystalline semiconductor film 436 is formed by being trapped in the film 437. (See FIG. 13B.) The crystalline semiconductor film 436 and the n-type semiconductor film 437 are patterned to form a crystalline semiconductor layer 438a and a crystalline semiconductor layer 438b. After that, a mask 440a covering the crystalline semiconductor layer 438a and the n-type semiconductor layer 439, and a mask 440b covering the n-type semiconductor layer 446 over the channel formation region in the crystalline semiconductor layer 438b are formed, and the p-type is formed. An impurity element 441 to be added is added to the n-type semiconductor layer. The semiconductor layer having n-type conductivity is added to the p-type semiconductor layer by adding the impurity element imparting p-type so that the concentration is 2 to 10 times the concentration of the impurity element imparting n-type. The type is inverted, so that a p-type impurity region 447a and a p-type impurity region 447b can be formed (see FIG. 13C).

The source or drain electrode layer 442a, the source or drain electrode layer 442b, the source or drain electrode layer 442c, and the source or drain electrode layer 442d are formed by a photolithography process (see FIG. 13D). . With the source or drain electrode layer 442a, the source or drain electrode layer 442b, the source or drain electrode layer 442c, and the source or drain electrode layer 442d as masks, the crystalline semiconductor layer 438a and the crystalline semiconductor layer 438b The n-type semiconductor layer 439 and the n-type semiconductor layer 446 are etched to form a semiconductor layer 444a, a semiconductor layer 444b, an n-type semiconductor layer 445a, an n-type semiconductor layer 445b, and a p-type semiconductor layer. A semiconductor layer 445d having 445c and a p-type can be formed (see FIG. 13E). Etching may be performed by dry etching or wet etching, the source electrode layer or the drain electrode layer may be etched by wet etching using an etchant, and the semiconductor layer may be etched by dry etching. Alternatively, wet etching using an HNO ₃ solution of the source electrode layer and the drain electrode layer may be performed, and then O ₂ ashing may be performed.

  Through the above steps, an n-channel thin film transistor and a p-channel thin film transistor can be formed over the same substrate.

    This embodiment mode can be used in combination with each of Embodiment Mode 1, Embodiment Mode 2, Embodiment Mode 3, Embodiment Mode 4, and Embodiment Mode 5.

(Embodiment 7)
An embodiment of the present invention will be described with reference to FIG. This embodiment is an example of manufacturing two types of thin film transistors: an n-channel thin film transistor and a p-channel thin film transistor. Therefore, repetitive description of the same portion or a portion having a similar function is omitted.

  A gate electrode layer 451a and a gate electrode layer 451b are formed over the substrate 450, and a gate insulating film 452a and a gate insulating film 452b are formed. Note that as shown in FIG. 14, a thin gate insulating film is formed over the gate insulating film 452b, and the gate insulating layer has a three-layer structure. A metal element 453 is added over the gate insulating film 452b to form an amorphous semiconductor film 454, and a semiconductor film 456 containing a rare gas element as an impurity element is formed (see FIG. 14A). Next, heat treatment is performed to crystallize the amorphous semiconductor film 454 to form the crystalline semiconductor film 455, and at the same time, gettering of a metal element contained in the crystalline semiconductor film 455 is performed. By the heat treatment, the metal element contained in the crystalline semiconductor film 455 is gettered, moved to and captured in the semiconductor film 456 having a rare gas element in the direction of the arrow, and the crystalline semiconductor film 455 is formed. (See FIG. 14B.)

  The semiconductor film 456 used as the gettering sink is removed by etching. The crystalline semiconductor film 455 is patterned to form a mask 458a covering the channel formation region 457a and a mask 458b covering the semiconductor layer 457b, and an impurity element 460 imparting n-type conductivity is added, and an n-type impurity region 459a and n-type impurity region 459a are added. An impurity region 459b is formed (see FIG. 14C).

  The mask 458a and the mask 458b are removed, and a mask 461a that covers the n-type impurity region 459a, the channel formation region 457a, and the n-type impurity region 459b, and a mask 461b that covers the channel formation region 465 are newly formed. An impurity element 463 to be added is added. A p-type impurity region 462a and a p-type impurity region 462b are formed using an impurity element imparting p-type (see FIG. 14D). The n-type impurity region 459a, the n-type impurity region 459b, the p-type impurity region 462a, and the p-type impurity region 462b function as a source region or a drain region. A source or drain electrode layer 464a, a source or drain electrode layer 464b, a source or drain electrode layer 464c, and a source or drain electrode layer 464d are formed in contact with the source or drain region (FIG. 14). (See (E).)

    Through the above steps, an n-channel thin film transistor and a p-channel thin film transistor can be formed over the same substrate. Since the number of deposition steps can be reduced as compared with Embodiment Mode 6, throughput can be improved.

(Embodiment 8)
An embodiment of the present invention will be described with reference to FIG. This embodiment is an example in which two types of thin film transistors, an n-channel thin film transistor and a p-channel thin film transistor, are manufactured, and the gettering process is different. Therefore, repetitive description of the same portion or a portion having a similar function is omitted.

  A gate electrode layer 471a and a gate electrode layer 471b are formed over the substrate 470, and a gate insulating film 472a and a gate insulating film 472b are formed. As shown in FIG. 15, a thin gate insulating film is formed over the gate insulating film 472b, and the gate insulating layer has a three-layer structure. A metal film containing a metal element that promotes crystals is formed over the gate insulating film 472b to form an amorphous semiconductor film. The metal film and the amorphous semiconductor film are patterned to form a metal layer 484a, a metal layer 484b, an amorphous semiconductor layer 473a, and an amorphous semiconductor layer 473b (see FIG. 15A).

A mask 474a covering the amorphous semiconductor layer 483a in the channel formation region and a mask 474b covering the amorphous semiconductor layer 483b in the channel formation region are formed, an impurity element 476 imparting n-type conductivity is added, and an n-type impurity region is added 475a, an n-type impurity region 475b, an n-type impurity region 475c, and an n-type impurity region 475d are formed (see FIG. 15B). After that, heat treatment is performed to crystallize the amorphous semiconductor layer 483a in the channel formation region and the amorphous semiconductor layer 483b in the channel formation region to form the crystalline semiconductor layer 478a and the crystalline semiconductor layer 478b. The metal elements contained in the crystalline semiconductor layer 478a and the crystalline semiconductor layer 478b that is the channel formation region are gettered, and the n-type impurity region 477a, the n-type impurity region 477b, and the n-type impurity region 477b in the direction of the arrows, respectively. A crystalline semiconductor layer 478a which is a channel formation region and a crystalline semiconductor layer 478b which is a channel formation region in which the metal element is removed and reduced are transferred to and trapped in the impurity region 477c and the n-type impurity region 477d. (See FIG. 15C). In addition, the added impurity element imparting n-type can be activated by this heat treatment.

  A mask 479a covering the n-type impurity region 477a, the channel formation region 478a, and the n-type impurity region 477b and a mask 479b covering the channel formation region 478b are formed, and an impurity element 481 imparting p-type conductivity is added. A p-type impurity region 480a and a p-type impurity region 480b are formed using an impurity element imparting p-type (see FIG. 15D). The n-type impurity region 477a, the n-type impurity region 477b, the p-type impurity region 480a, and the p-type impurity region 480b function as a source region or a drain region. A source or drain electrode layer 482a, a source or drain electrode layer 482b, a source or drain electrode layer 482c, and a source or drain electrode layer 482d are formed in contact with the source or drain region (FIG. 15). (See (E).)

    Through the above steps, an n-channel thin film transistor and a p-channel thin film transistor can be formed over the same substrate. Since the number of film formation steps can be reduced as compared with Embodiment Mode 7, throughput can be improved.

(Embodiment 9)
This embodiment will be described with reference to FIGS. In this embodiment, the pixel region is a pixel region manufactured in Embodiment Mode 1 and the thin film transistor included in the pixel is a multi-gate type. Further, the peripheral driver circuit region is also manufactured using a thin film transistor using the present invention, and a CMOS including an n-channel thin film transistor and a p-channel thin film transistor manufactured in Embodiment 6 is applied. Therefore, repetitive description of the same portion or a portion having a similar function is omitted.

    FIG. 19 is a top view of a pixel region of a liquid crystal display device manufactured in this embodiment mode. FIGS. 16 to 19 and FIG. 20B are lines EF and GH in FIG. FIG. 16 to FIG. 19 is a cross-sectional view corresponding to line IJ, which is a peripheral driver circuit region of the liquid crystal display device of FIG.

  A conductive film is formed over the polarizing plate 376 and the substrate 300, and patterning is performed using a resist mask, and the gate electrode layer 301, the gate electrode layer 302, the gate electrode layer 303a, the gate electrode layer 303b, the gate electrode layer 303c, and the pixel electrode are formed. Layer 304 is formed. In this embodiment mode, the gate electrode layer is formed using a single layer of a transparent conductive film, but may have a stacked structure. As the stacked structure, Ta, Ti, W, Mo, Cr, and a nitride film of the above elements can be used. Specifically, TaN \ W, TaN \ Mo, TaN \ Cr, TiN \ W, TiN \ Mo, TiN \ Cr, etc. can be used. In this embodiment, indium tin oxide containing silicon oxide (ITSO) is formed by a sputtering method, and is baked to form a conductive film in the vicinity including the gate electrode layer formation region. This conductive film is precisely patterned using a mask finely processed by a photolithography process, and a gate electrode layer 301, a gate electrode layer 302, a gate electrode layer 303a, a gate electrode layer 303b, a gate electrode layer 303c, and a pixel electrode layer 304 is formed.

    A gate insulating film is formed over the gate electrode layer 301, the gate electrode layer 302, the gate electrode layer 303a, the gate electrode layer 303b, the gate electrode layer 303c, and the pixel electrode layer 304, and crystallization is promoted and promoted over the gate insulating film. A metal film 307 is formed as an element. Since the metal film 307 is very thin, the shape as a film may not be maintained. In this embodiment, an aqueous solution containing Ni of 100 ppm is applied by a spin coating method to form the metal film 307. An amorphous semiconductor film 306 is formed over the metal film 307 (see FIG. 16A). In this embodiment mode, a gate insulating film 305a made of silicon nitride and a gate insulating film 305b made of silicon oxide are stacked as the gate insulating film. As the amorphous semiconductor film 306, an amorphous silicon film is used. In this embodiment, as shown in Embodiment 1, the gate insulating film has a three-layer structure.

  An n-type semiconductor film 308 is formed over the amorphous semiconductor film 306. In this embodiment, as the n-type semiconductor film 308, an amorphous silicon film containing phosphorus (P) as an impurity element imparting n-type is formed to a thickness of 100 nm by a plasma CVD method (FIG. 14B). Next, the amorphous semiconductor film 306 is heated and crystallized, and at the same time, a metal element is gettered using the n-type semiconductor film 308 as a gettering sink (see FIG. 14C). By the heat treatment, the metal element in the crystalline semiconductor film moves in the direction of the arrow by the heat treatment and is captured in the semiconductor film 308 having n-type conductivity. Therefore, the amorphous semiconductor film 306 becomes a crystalline semiconductor film 310 in which the metal element in the film is reduced, and the semiconductor film 308 having n-type conductivity is an impurity element imparting n-type conductivity (P in this embodiment mode). Thus, an n-type semiconductor film 311 containing metal element (Ni in this embodiment) is formed. In this embodiment, heat treatment is performed at 550 ° C. for 4 hours, and the crystalline semiconductor film 310 is formed and gettering is performed.

    The crystalline semiconductor film 310 and the n-type semiconductor film 311 are patterned to have a semiconductor layer 312, a semiconductor layer 313, a semiconductor layer 314, an n-type semiconductor layer 315, an n-type semiconductor layer 316, and an n-type A semiconductor layer 317 can be formed (see FIG. 17A). Patterning of these semiconductor layers can also be precisely performed using a resist mask formed using a photolithography process.

    Next, the mask 318a covering the semiconductor layer 312, the n-type semiconductor layer 315, the channel formation region of the semiconductor layer 316, and the mask 318b covering the channel formation region of the n-type semiconductor layer 316, the semiconductor layer 314, and the n-type are formed. A mask 318 c that covers the semiconductor layer 317 is formed. An impurity element 319 imparting p-type conductivity is added to form a p-type impurity region 320a and a p-type impurity region 320b in the p-type semiconductor layer 316 (see FIG. 17B). In this embodiment mode, an impurity element imparting p-type conductivity is added using an ion doping method. After that, heat treatment is performed at 550 ° C. for 4 hours to activate the impurity element addition region.

In this embodiment mode, a CMOS structure is used in the drive circuit area to function as an inverter. In the case of only PMOS and NMOS only, the gate electrode layer of some TFTs and the source electrode layer or drain electrode layer are connected. Such an example is shown in FIG. A part of the gate insulating film 305a and the gate insulating film 305b is etched using a photomask to form a contact hole 890 as shown in FIG. In this embodiment mode, the first electrode layer to be the pixel electrode layer is connected to the source electrode layer or the drain electrode layer through a contact hole formed in the interlayer insulating film. And the first electrode layer may be connected without an interlayer insulating film interposed therebetween. In this case, the opening reaching the first electrode layer can be formed simultaneously with the contact hole 890. Thereafter, a source electrode layer or a drain electrode layer is formed in these contact holes, and electrically connected to the gate electrode layer or the first electrode layer, respectively.
By connecting the source or drain electrode layer 327b and the gate electrode layer 302, a thin film transistor 335 and a thin film transistor 336 to be formed later can function as an inverter even if they are NMOS transistors and PMOS transistors. As described above, in this embodiment mode, the thin film transistor 335 and the thin film transistor 336 have a CMOS structure, and thus are illustrated in FIGS. Even if it is not structured, it can function as an inverter.

    After removing the mask 318a, the mask 318b, and the mask 318c, a conductive film is formed over the semiconductor layer 312, the semiconductor layer 313, and the semiconductor layer 314, and is patterned by using the mask formed by a photolithography process. A conductive film 321a, a conductive film 321b, a conductive film 321c, a conductive layer 322a, a conductive film 322b, and a conductive film 322c are formed (see FIG. 17C). In the same step, a conductive layer 370 serving as a capacitor wiring layer is also formed over the gate insulating film 305b over the pixel electrode layer 304.

    As described with reference to FIG. 7 in Embodiment 1, the conductive layer 321 and the conductive layer 322 are precisely patterned, and the source or drain electrode layer 327a, the source or drain electrode layer 327b, and the source electrode layer are patterned. Alternatively, the drain electrode layer 327c, the source or drain electrode layer 328a, the source or drain electrode layer 328b, the source or drain electrode layer 328c, and the capacitor wiring layer 332 are formed. Source or drain electrode layer 327a, Source or drain electrode layer 327b, Source or drain electrode layer 327c, Source or drain electrode layer 328a, Source or drain electrode layer 328b, Source or drain electrode layer 328b Using the electrode layer 328c as a mask, the semiconductor layer 312, the semiconductor layer 313, the semiconductor layer 314, the n-type semiconductor layer 315, the n-type semiconductor layer 316, and the n-type semiconductor layer 317 are etched, and the semiconductor layer 371, a semiconductor layer 372, a semiconductor layer 373, an n-type semiconductor layer 324a, an n-type semiconductor layer 324b, a p-type semiconductor layer 325a, a p-type semiconductor layer 325b, an n-type semiconductor layer 326a, An n-type semiconductor layer 326b and an n-type semiconductor layer 326c are formed. To. Etching can be dry etching or wet etching. In this embodiment mode, a dry etching method is used.

    Through the above steps, an n-channel thin film transistor 335, a p-channel thin film transistor 336, an n-channel thin film transistor 337, and a capacitor 338 which form a CMOS can be formed (see FIG. 18A). Although a CMOS structure is used in this embodiment mode, the present invention is not limited to this, and a PMOS structure or an NMOS structure may be used.

    An insulating film 330 to be a passivation film is formed. In this embodiment, the insulating film 330 is formed using a stacked film of a silicon oxide film with a thickness of 150 nm and a silicon nitride film with a thickness of 200 nm from the side in contact with the semiconductor layer. The insulating film 330 may be formed using another silicon-containing film, or a silicon oxynitride film may be used instead of the silicon oxide film, and a silicon oxynitride film and a silicon nitride film may be stacked.

    The insulating film 330 is formed so as to contain oxygen, and heat treatment is performed in a nitrogen atmosphere at a temperature of 300 to 500 ° C. to hydrogenate the semiconductor layer.

    An insulating film 339 is formed over the insulating film 330. In this embodiment, a silicon oxide film including an alkyl group is formed using a slide coater. An opening 340a reaching the source or drain electrode layer 328b is formed in the insulating film 339 and the insulating film 330, and an opening reaching the pixel electrode layer 304 is formed in the insulating film 339, the insulating film 330, the gate insulating film 305a, and the gate insulating film 305b. An opening 340c reaching 340b and the gate electrode layer 303c is formed (see FIG. 18B). For the patterning for forming the opening, the fine processing by the laser beam of the present invention can be used. In this embodiment mode, the opening is formed by dry etching.

    Next, a gate wiring layer 341 and a gate wiring layer 342 are formed. In this embodiment, a gate wiring layer is formed over the insulating film 339 by a sputtering method using Ag (silver), and then patterned using a photolithography process, so that the source or drain electrode layer 328b and the pixel electrode layer 304 are formed. Are formed, and a gate wiring layer 342 which is electrically connected to the gate electrode layer 303c is formed (see FIG. 18C).

As a conductive material for forming the gate wiring layer 341 that electrically connects the source or drain electrode layer 328b and the pixel electrode layer 304 or the gate wiring layer 342 that is electrically connected to the gate electrode layer 303c, Ag (silver) ), Au (gold), Cu (copper), W (tungsten), Al (aluminum), or the like can be used. Further, light-transmitting indium tin oxide (ITO), ITSO made of indium tin oxide and silicon oxide, organic indium, organic tin, zinc oxide, titanium nitride, or the like may be combined.

    FIG. 21 is a top view of a pixel region of a liquid crystal display device manufactured in the embodiment mode. The thin film transistor provided in the pixel region is a multi-gate type. In the pixel region, the gate electrode layer 303a, the gate electrode layer 303b, the pixel electrode layer 304, the semiconductor layer 373, the source or drain electrode layer 328a, the source or drain electrode layer 328b, the source or drain electrode layer 328c , Capacitor wiring layer 332, gate wiring layer 342, and gate wiring layer 341.

  Next, as shown in FIG. 19, an insulating film 343 called an alignment film is formed by a printing method or a spin coating method so as to cover the pixel electrode layer 304. Note that the insulating film 343 can be selectively formed by a screen printing method or an offset printing method. Thereafter, a rubbing process is performed. Subsequently, a sealant 351 is formed in a peripheral region where pixels are formed.

  After that, an insulating substrate 345 functioning as an alignment film, a colored layer 346 functioning as a color filter, a conductor layer 347 functioning as a counter electrode, and a counter substrate 348 provided with a polarizing plate 350a and the substrate 300 are interposed through a spacer 375. A liquid crystal display panel can be manufactured by bonding and providing a liquid crystal layer 344 in the gap (FIG. 20). The substrate 300 is also provided with a polarizing plate 350b on the surface opposite to the surface having TFTs. The spacer may be provided by dispersing particles having a size of several μm, but in this embodiment, a method of forming a resin film on the entire surface of the substrate and then patterning it is employed. After applying such a spacer material with a spinner, it is formed into a predetermined pattern by exposure and development processing. Further, it is cured by heating at 150 to 200 ° C. in a clean oven or the like. The spacers produced in this way can have different shapes depending on the conditions of exposure and development processing, but preferably, the spacers are columnar and the top is flat, so that the opposite substrate is When combined, the mechanical strength of the liquid crystal display panel can be ensured. The shape can be a conical shape, a pyramid shape, or the like, and there is no particular limitation. A filler may be mixed in the sealing material, and a shielding film (black matrix) or the like may be formed on the counter substrate 348. In addition, an FPC 354 is bonded to a terminal electrode layer 352 for electrically connecting the inside and the outside of the liquid crystal display device with an anisotropic conductive film 353 so as to be electrically connected to the terminal electrode layer 352.

    In the liquid crystal display device in FIG. 20 described in this embodiment, the gate electrode layer 301, the gate electrode layer 302, the gate electrode layer 303a, the gate electrode layer 303b, and the pixel electrode layer 304 are illustrated in a single layer structure. As described above, two or more gate electrode layers may be stacked. FIG. 44 shows an example in which the gate electrode layer and the capacitor wiring layer are stacked.

  As the stacked structure, Ta, Ti, W, Mo, Cr, and a nitride film of the above elements can be used. Specifically, TaN \ W, TaN \ Mo, TaN \ Cr, TiN \ W, TiN \ Mo, TiN \ Cr, etc. can be used. In this embodiment, TaN is used as the first gate electrode layer 301a, the first gate electrode layer 302a, the first gate electrode layer 303a1, the first gate electrode layer 303b1, and the first gate electrode layer 303c1, W is used for the second gate electrode layer 301b, the second gate electrode layer 302b, the second gate electrode layer 303a2, the second gate electrode layer 303b2, and the second gate electrode layer 303c2. Also in the pixel electrode layer formed in the same step, a TaN film is formed as the first pixel electrode layer 304a, and a W film is formed as the second pixel electrode layer 304b. Thus, the gate electrode layer and the pixel electrode layer can have a stacked structure. Further, the pixel electrode layer may be formed in a single layer structure, and the gate electrode layer may be formed in a stacked structure. Conversely, the pixel electrode layer may be formed in a stacked structure and the gate electrode layer may be formed in a single layer structure. What is necessary is just to set suitably according to the function requested | required of a liquid crystal display device.

    Through the above steps, an inverted staggered thin film transistor having a crystalline semiconductor film can be formed. Since the thin film transistor formed in this embodiment is formed using a crystalline semiconductor film, it has higher mobility than a thin film transistor formed using an amorphous semiconductor film. In addition, the source region and the drain region include a metal element in addition to the impurity element imparting one conductivity type. For this reason, a source region and a drain region with low resistivity can be formed. As a result, a liquid crystal display device that requires high-speed operation can be manufactured. Therefore, it is possible to manufacture a liquid crystal display device that can display with a high response speed and a high viewing angle as in the OCB mode.

    Further, compared to a thin film transistor formed using an amorphous semiconductor film, threshold shift is less likely to occur, and variations in thin film transistor characteristics can be reduced.

    By simultaneously performing the crystallization of the amorphous semiconductor film and the gettering process, the process can be shortened. Further, since the metal element mixed in the semiconductor film in the film formation step is gettered by the gettering step, off current can be reduced. Therefore, the contrast can be improved by providing such a thin film transistor in the switching element of the liquid crystal display device.

(Embodiment 10)
In Embodiment 1, a gate electrode layer, a source or drain electrode layer (including a source wiring layer) and a capacitor wiring layer are stacked with a gate insulating film interposed therebetween, and a source electrode layer or a drain electrode layer (source wiring) A multilayer structure in which a gate wiring layer is stacked with an interlayer insulating film interposed therebetween. In this embodiment, an example in which these stacked structures are different will be described with reference to FIGS. 31 to 36 and FIG. FIGS. 30A to 35A are top views of the liquid crystal display device, and FIGS. 30B to 32B are lines X1−1 in FIGS. 30A to 32A. It is sectional drawing by V1. FIGS. 30A to 32A are top views of the liquid crystal display device, and FIGS. 30C to 35C are lines X1−1 in FIGS. 30A to 35A. It is sectional drawing by V1.

    30A is a top view of the liquid crystal display device, FIG. 30B is a cross-sectional view taken along line X1-V1 in FIG. 30A, and FIG. 30C is in FIG. It is sectional drawing by line MN. The liquid crystal display device illustrated in FIG. 30 does not have a structure in which the source electrode layer or the drain electrode layer and the pixel electrode layer are electrically connected to each other through the gate wiring layer as described in Embodiment Mode 1. The electrode layer 610 is formed so as to be in direct contact with the pixel electrode layer 611 and is electrically connected. In this manner, the source or drain electrode layer 610 may be directly connected to the pixel electrode layer 611. In the case of a reflective liquid crystal display device, a reflective material is used for the source or drain electrode layer 610, and the pixel A structure in which the electrode layer 611 is stacked may be employed.

    In FIG. 30, in a pixel region of the liquid crystal display device, a gate electrode layer 601a, a gate electrode layer 601b, a pixel electrode layer 611, a gate insulating film 602a, a gate insulating film 602b, a capacitor wiring layer 604, and a source electrode are formed over a substrate 600. Layer or drain electrode layer 603a, source or drain electrode layer 603b, gate wiring layer 607, semiconductor layer 608, n-type semiconductor layer 609a, n-type semiconductor layer 609b, insulating film 605 which is a passivation film, insulating A film 606 is formed. Note that in this embodiment mode, as shown in Embodiment Mode 1, the gate insulating film has a three-layer structure.

    The insulating film 605 is not necessarily required; however, when the insulating film 605 is formed, the insulating film 605 functions as a passivation film, and thus the reliability of the liquid crystal display device is further improved. In addition, when the insulating film 605 is formed and heat treatment is performed, the semiconductor layer can be hydrogenated with hydrogen contained in the insulating film 605.

    As shown in FIG. 30B, the source or drain electrode layer 603b is stacked with the gate wiring layer 607 with an insulating film 606 which is an interlayer insulating film interposed therebetween. The gate wiring layer 607 includes a gate electrode layer. The gate electrode layer 601b is connected to the insulating film 606, the insulating film 605, the gate insulating film 602a, and the contact hole formed in the gate insulating film 602b. Thus, the gate wiring layer 607 is not short-circuited with the source or drain electrode layer 603b and the capacitor wiring layer 604.

    FIG. 31A is a top view of the liquid crystal display device, and FIG. 31B is a cross-sectional view taken along line X2-V2 in FIG. In FIG. 31, in a pixel region of the liquid crystal display device, a gate electrode layer 621a, a gate electrode layer 621b, a gate insulating film 622a, a gate insulating film 622b, a capacitor wiring layer 624, a source electrode layer or a drain electrode layer are formed over a substrate 620. 623a, a source or drain electrode layer 623b, a gate wiring layer 627a, a gate wiring layer 627b, an insulating film 625 which is a passivation film, and an insulating film 626 are formed.

    As shown in FIG. 31B, the source or drain electrode layer 623b is stacked with the gate wiring layer 627b with an insulating film 626 that is an interlayer insulating film interposed therebetween. The gate wiring layer 627b includes a gate electrode layer 621a and the gate electrode layer 621b are connected to each other through a contact hole formed in the insulating film 626, the insulating film 625, the gate insulating film 622a, and the gate insulating film 622b. Therefore, the gate wiring layer 627b is not short-circuited with the source or drain electrode layer 623b and the capacitor wiring layer 624. Further, the liquid crystal display device shown in FIG. 31 has a structure in which the gate wiring layer and the gate electrode layer are formed intermittently rather than continuously, and are electrically connected to each other through a contact hole. ing. Therefore, in the region where the source or drain electrode layer 623b and the capacitor wiring layer 624 are formed, the gate electrode layer 621a and the gate electrode layer 621b are formed in contact with the gate wiring layer 627b formed over the insulating film 626. It is electrically connected by connecting.

    32A is a top view of the liquid crystal display device, and FIG. 32B is a cross-sectional view taken along line X3-V3 in FIG. 32, in the pixel region of the liquid crystal display device, a gate electrode layer 631a, a gate electrode layer 631b, a gate insulating film 632a, a gate insulating film 632b, a capacitor wiring layer 634, a source electrode layer or a drain electrode layer are formed over a substrate 630. 633a, a source or drain electrode layer 633b, a gate wiring layer 637a, a gate wiring layer 637b, a wiring layer 638a, a wiring layer 638b, an insulating film 635 which is a passivation film, and an insulating film 636 are formed.

    As shown in FIG. 32B, the source or drain electrode layer 633b is stacked with the gate wiring layer 637b with the insulating film 636 that is an interlayer insulating film interposed therebetween. In the liquid crystal display device illustrated in FIG. 31, the gate electrode layer 621a is directly connected to the gate wiring layer 627a and the gate wiring layer 627b. However, in the liquid crystal display device shown in FIG. 33, the gate electrode layer 631a, the gate wiring layer 637a, and the gate wiring layer 637b are electrically connected to each other through the wiring layer 638a formed in the same process and using the same material as the source electrode layer. Connected. Therefore, the gate electrode layer 631a is connected to the wiring layer 638a formed over the gate insulating film 632a and the gate insulating film 632b through a contact hole, and the wiring layer 638a is connected to the gate wiring layer 637a and the gate wiring layer 637b through the contact hole. Connect. Therefore, the gate electrode layer 631a, the gate wiring layer 637a, and the gate wiring layer 637b are electrically connected. Since the source or drain electrode layer 633b and the capacitor wiring layer 634 are stacked with the gate wiring layer 637b through the insulating film 636 which is an interlayer insulating film, the source or drain electrode layer 633b and the capacitor wiring layer 634 and the gate are stacked. The wiring layer 637b is not short-circuited.

    30, 31 and 32 show the case where an insulating film is formed as an interlayer insulating film so as to cover a wide range. FIG. 33, FIG. 34 and FIG. 35 show an example in which an interlayer insulating film separating wiring layers is selectively formed only at a necessary portion by using a photolithography process.

    FIG. 33 corresponds to the liquid crystal display device of FIG. 30, FIG. 34 corresponds to FIG. 31, and FIG. 35 corresponds to the liquid crystal display device of FIG. FIG. 33A is a top view of the liquid crystal display device, and FIG. 33B is a cross-sectional view taken along line Y1-Z1 in FIG. In FIG. 33, an insulating film 650 is formed by a photolithography process so as to cover the source or drain electrode layer 603b and the capacitor wiring layer 604. A gate wiring layer 607 is formed so as to straddle over the insulating film 650. An insulating film 660 is formed on the gate wiring layer 607 as a passivation film. Although the insulating film 660 is not necessarily required, formation of the insulating film 660 can improve reliability. In this embodiment mode, the insulating film 650 is formed as a single layer; however, an insulating film may be formed on or below the insulating film 650 to have a stacked structure.

    34A is a top view of the liquid crystal display device, and FIG. 34B is a cross-sectional view taken along line Y2-Z2 in FIG. 34, as in FIG. 33, an insulating film 651 is formed by a photolithography process so as to cover the source or drain electrode layer 623b and the capacitor wiring layer 624. A gate wiring layer 627b is formed so as to straddle over the insulating film 651, and is connected to the gate electrode layer 621a through a contact hole. An insulating film 661 is formed as a passivation film over the gate wiring layer 627a.

    35A is a top view of the liquid crystal display device, and FIG. 35B is a cross-sectional view taken along line Y3-Z3 in FIG. 35, as in FIG. 33, an insulating film 652 is formed by a photolithography process so as to cover the source or drain electrode layer 633b and the capacitor wiring layer 634. A gate wiring layer 637b is formed so as to straddle over the insulating film 652, and is electrically connected to the gate wiring layer 637a and the gate electrode layer 631a through the wiring layer 638a.

    When an insulating film for preventing a short circuit between wiring layers, such as the insulating film 650, the insulating film 651, and the insulating film 652, is selectively formed, it can be formed so that the wirings are in direct contact with each other. The number of steps for forming contact holes is reduced. Therefore, the process can be simplified and low cost and high productivity can be obtained.

    The liquid crystal display device in FIG. 40 is also an example in which the insulating film 653 provided to physically separate the source or drain electrode layer 643b and the capacitor wiring layer 644 from the wiring layer 647b is selectively formed using a photolithography process. In the liquid crystal display device shown in FIGS. 33 to 35, a short circuit between the source electrode layer or the drain electrode layer and the gate wiring layer is prevented by forming the gate wiring layer over the insulating film. In the liquid crystal display device in FIG. 40, the wiring layer 647a and the wiring layer 647b are formed in the step of forming the gate electrode layer 641a and the gate electrode layer 641b. After that, before forming the source or drain electrode layer 643a and the capacitor wiring layer 644, part of the gate insulating film covering the wiring layer 647a and the wiring layer 647b is removed by etching. An insulating film 653 is selectively formed over part of the wiring layer 647b by a photolithography process, and a source or drain electrode layer 643a and a capacitor wiring layer 644 are formed over the insulating film 653. In the same process as the formation of the source or drain electrode layer 643b and the capacitor wiring layer 644, the wiring layer 648a and the wiring layer 648b are formed in contact with the gate electrode layer 641a and the gate electrode layer 641b, respectively. The wiring layer 648a and the wiring layer 648b are electrically connected by the wiring layer 647b under the insulating film 653. In this manner, the gate wiring layer and the gate electrode layer can be electrically connected under the insulating film 653.

    As shown in the above steps, a highly reliable liquid crystal display device can be manufactured with low cost and high productivity.

(Embodiment 11)
Next, a mode in which a driver circuit for driving is mounted on the liquid crystal display panel manufactured according to Embodiments 1 to 10 will be described.

  First, a liquid crystal display device employing a COG method is described with reference to FIG. A pixel portion 2701 for displaying information such as characters and images is provided over the substrate 2700. A substrate provided with a plurality of drive circuits is divided into rectangular shapes, and a divided drive circuit (hereinafter referred to as a driver IC) 2751 is mounted on the substrate 2700. FIG. 29A illustrates a form in which a plurality of driver ICs 2751 and an FPC 2750 are mounted on the tip of the driver ICs 2751. Further, the size to be divided may be substantially the same as the length of the side of the pixel portion on the signal line side, and a tape may be mounted on the tip of the driver IC on a single driver IC.

  Alternatively, a TAB method may be employed. In that case, a plurality of tapes may be attached and driver ICs may be mounted on the tapes as shown in FIG. As in the case of the COG method, a single driver IC may be mounted on a single tape. In this case, a metal piece or the like for fixing the driver IC may be attached together due to strength problems.

  A plurality of driver ICs mounted on these display panels may be formed on a rectangular substrate having a side of 300 mm to 1000 mm or more from the viewpoint of improving productivity.

  That is, a plurality of circuit patterns having a drive circuit portion and an input / output terminal as one unit may be formed on the substrate, and finally divided and taken out. The long side of the driver IC may be formed in a rectangular shape having a long side of 15 to 80 mm and a short side of 1 to 6 mm in consideration of the length of one side of the pixel portion and the pixel pitch. Or a length obtained by adding one side of the pixel portion and one side of each driver circuit.

  The advantage of the external dimensions of the driver IC over the IC chip lies in the length of the long side. When a driver IC formed with a long side of 15 to 80 mm is used, the number required for mounting corresponding to the pixel portion is as follows. This is less than when an IC chip is used, and the manufacturing yield can be improved. Further, when a driver IC is formed over a glass substrate, the shape of the substrate used as a base is not limited, and thus productivity is not impaired. This is a great advantage compared with the case where the IC chip is taken out from the circular silicon wafer.

  In the case where the driver circuit 3704 on the scanning line side is formed over the substrate as shown in FIG. 28B, the driver in which the driver circuit driver circuit on the signal line side is formed in the region outside the pixel region 3701. IC is mounted. These driver ICs are drive circuits on the signal line side. In order to form a pixel region corresponding to RGB full color, the number of signal lines in the XGA class is 3072 and the number in the UXGA class is 4800. The signal lines formed in such a number are divided into several blocks at the end of the pixel region 3701 to form lead lines, and are collected according to the pitch of the output terminals of the driver IC.

  The driver IC is preferably formed of a crystalline semiconductor formed over a substrate, and a thin film transistor using the present invention can be used. In addition, since the mobility and response speed are good, high-speed driving is possible, the operating frequency of the element can be improved as compared with the prior art, and there is less variation in characteristics, so that high reliability can be obtained.

  In the pixel region, signal lines and scanning lines intersect to form a matrix, and transistors are arranged corresponding to the respective intersections. A thin film transistor using the present invention can also be applied to a transistor arranged in a pixel region. A thin film transistor manufactured by applying the present invention is effective in manufacturing a large-screen liquid crystal display device because a relatively high mobility can be obtained by a simplified process. Therefore, this thin film transistor can be used as a switching element of a pixel or an element constituting a driving circuit on the scanning line side. Therefore, a display panel that realizes system-on-panel can be manufactured.

  As shown in FIGS. 29A and 29B, driver ICs may be mounted as both the scanning line driver circuit and the signal line driver circuit. In that case, the specifications of the driver ICs used on the scanning line side and the signal line side may be different.

  In that case, it is preferable that the specifications of the driver ICs used on the scanning line side and the signal line side are different. For example, although a transistor constituting the driver IC on the scanning line side is required to have a withstand voltage of about 30 V, the driving frequency is 100 kHz or less, and a relatively high speed operation is not required. Therefore, it is preferable to set the channel length (L) of the transistors forming the driver on the scanning line side to be sufficiently large. On the other hand, it is sufficient for the transistor of the driver IC on the signal line side to have a withstand voltage of about 12V, but the drive frequency is about 65 MHz at 3V, and high speed operation is required. Therefore, it is preferable to set the channel length and the like of the transistors constituting the driver on the micron rule. Note that the channel length direction corresponds to the direction in which current flows in the channel formation region, in other words, the direction in which charges move.

  The method for mounting the driver IC is not particularly limited, and a known COG method, wire bonding method, or TAB method can be used.

  By setting the thickness of the driver IC to the same thickness as that of the counter substrate, the height between the two becomes substantially the same, which contributes to the thinning of the liquid crystal display device as a whole. Further, by manufacturing each substrate with the same material, thermal stress does not occur even if a temperature change occurs in the liquid crystal display device, and the characteristics of the circuit manufactured by the TFT are not impaired. In addition, the number of driver ICs to be mounted in one pixel region can be reduced by mounting the driver circuit with a driver IC longer than the IC chip as shown in this embodiment mode. .

  As described above, a driving circuit can be incorporated in the liquid crystal display panel.

(Embodiment 12)
In this embodiment mode, FIG. 26 shows the positional relationship between the end portions of the gate electrode layer, the source electrode layer, and the drain electrode layer, that is, the relationship between the width of the gate electrode layer and the channel length in the above embodiment mode. It explains using.

  FIG. 26A illustrates a gate electrode layer 541, a gate insulating film 542a, a gate insulating film 542b, a semiconductor layer 543, a semiconductor layer 544a having one conductivity, and a semiconductor layer 544b having one conductivity, which are formed over a substrate 540. , A thin film transistor including a source or drain electrode layer 545a and a source or drain electrode layer 545b. Note that in this embodiment mode, as shown in Embodiment Mode 1, the gate insulating film has a three-layer structure.

    In FIG. 26A, end portions of the source and drain electrode layers 545a and 545b overlap with the gate electrode layer 541 by c1. Here, a region where the source and drain electrode layers 545a and the source and drain electrode layers 545b overlap is referred to as an overlap region. That is, the width b1 of the gate electrode layer is larger than the channel length a1. The width c1 of the overlap region is represented by (b1-a1) / 2. An n-channel TFT having such an overlap region preferably has an n + region and an n − region between the source and drain electrode layers and the semiconductor region. With this structure, the effect of relaxing the electric field is increased, and hot carrier resistance can be increased.

  FIG. 26B illustrates a gate electrode layer 551, a gate insulating film 552a, a gate insulating film 552b, a semiconductor layer 553, a semiconductor layer 554a having one conductivity, and a semiconductor layer 554b having one conductivity, which are formed over a substrate 550. , A thin film transistor including a source or drain electrode layer 555a and a source or drain electrode layer 555b.

    In FIG. 26B, the end portion of the gate electrode layer 551 is aligned with the end portions of the source and drain electrode layers 555a and 555b. That is, the width b2 of the gate electrode layer is equal to the channel length a2.

  FIG. 26C illustrates a gate electrode layer 561, a gate insulating film 562a, a gate insulating film 562b, a semiconductor layer 563, a semiconductor layer 564a having one conductivity, and a semiconductor layer 564b having one conductivity, which are formed over a substrate 560. , A thin film transistor including a source or drain electrode layer 565a and a source or drain electrode layer 565b.

  In FIG. 26C, the gate electrode layer 561 is separated from the end portions of the source and drain electrode layers 565a and the source and drain electrode layers 565a by c3. Here, a region where the gate electrode layer 561 is separated from the source and drain electrode layers 565a and the source and drain electrode layers 565a is referred to as an offset region. That is, the width b3 of the gate electrode layer is smaller than the channel length a3. The width c3 of the offset region is represented by (a3−b3) / 2. Since a TFT having such a structure can reduce off-state current, contrast can be improved when the TFT is used as a switching element of a liquid crystal display device.

  Further, a TFT having a so-called multi-gate structure in which the semiconductor region covers a plurality of gate electrodes may be used. A TFT having such a structure can also reduce off-state current.

(Embodiment 13)
In the above embodiment mode, the source electrode layer and the drain electrode layer having end portions perpendicular to the surface of the channel formation region are shown; however, the present invention is not limited to this structure. As shown in FIG. 25, it may be an end portion having an angle of greater than 90 degrees and less than 180 degrees, preferably 95 to 140 degrees, more preferably 135 to 140 degrees with respect to the surface of the channel formation region. Further, if the angle between the source electrode layer and the channel formation region surface is θ1, and the angle between the drain electrode layer and the channel formation region surface is θ2, θ1 and θ2 may be equal. It may be different. The source electrode and the drain electrode having such a shape can be formed by a dry etching method.

(Embodiment 14)
In this embodiment mode, a crystallization process of a semiconductor film which can be applied to the above embodiment mode will be described with reference to FIGS. FIG. 24B is a top view of FIG. FIG. 24D is a top view of FIG.

    In FIG. 24, a gate electrode layer 501, a gate insulating film 502a, and a gate insulating film 502b are formed on a substrate 500. Next, after forming a metal film, the metal film is selectively patterned by using a photolithography process. After the metal layer 503 is formed, an amorphous semiconductor film 504 is formed. A semiconductor film 505 containing an impurity is formed over the amorphous semiconductor film 504 (FIG. 24A). In this embodiment, the semiconductor film 505 containing an impurity contains an impurity element imparting n-type conductivity (in this embodiment, phosphorus is used). Note that in this embodiment mode, as shown in Embodiment Mode 1, the gate insulating film has a three-layer structure.

  Next, the amorphous semiconductor film 504 is simultaneously crystallized and gettered by heat treatment. When the amorphous semiconductor film is heated, crystal growth occurs in a direction parallel to the surface of the substrate from the contact portion between the metal layer 503 and the semiconductor film, as shown by arrows in FIGS. The crystalline semiconductor film 506 is formed. In addition, as the semiconductor film 505 containing an impurity, a semiconductor film 507 containing an impurity containing a metal element is formed. Note that crystallization is not performed in a portion far from the metal layer 503, and an amorphous portion remains.

s
Thus, crystal growth in a direction parallel to the substrate is referred to as lateral growth or lateral growth. Since crystal grains having a large grain size can be formed by lateral growth, a thin film transistor having higher mobility can be formed.

(Embodiment 15)
An example of a protection circuit included in the semiconductor device of the present invention will be described.

  As shown in FIG. 29, a protection circuit 2713 can be formed between the external circuit and the internal circuit. The protection circuit is composed of one or a plurality of elements selected from a TFT, a diode, a resistance element, a capacitance element, and the like, and the configurations and operations of some protection circuits will be described below. First, a configuration of an equivalent circuit diagram of a protection circuit arranged between an external circuit and an internal circuit and corresponding to one input terminal will be described with reference to FIG. The protection circuit illustrated in FIG. 42A includes p-channel thin film transistors 7220 and 7230, capacitor elements 7210 and 7240, and a resistance element 7250. The resistance element 7250 is a two-terminal resistor, and an input voltage Vin (hereinafter referred to as Vin) is applied to one end, and a low potential voltage VSS (hereinafter referred to as VSS) is applied to the other end.

  The protection circuit illustrated in FIG. 41B is an equivalent circuit diagram in which the p-channel thin film transistors 7220 and 7230 are replaced with rectifying diodes 7260 and 7270. The protection circuit illustrated in FIG. 41C is an equivalent circuit diagram in which the p-channel thin film transistors 7220 and 7230 are substituted with TFTs 7350, 7360, 7370, and 7380. In addition, as a protection circuit having a different structure from the above, the protection circuit illustrated in FIG. 41D includes resistors 7280 and 7290 and an n-channel thin film transistor 7300. A protection circuit illustrated in FIG. 41E includes resistors 7280 and 7290, a p-channel thin film transistor 7310, and an n-channel thin film transistor 7320. By providing the protection circuit, a rapid change in potential can be prevented, and destruction or damage of the element can be prevented, so that reliability is improved. Note that the element forming the protection circuit is preferably formed using an amorphous semiconductor with excellent withstand voltage. This embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 16)
A liquid crystal television device can be completed with the liquid crystal display panel manufactured according to the above embodiment mode. In the liquid crystal display panel, only the pixel portion is formed as shown in FIG. 28A, and the scanning line side driver circuit and the signal line side driver circuit are mounted by the TAB method as shown in FIG. In the case of being mounted by the COG method as shown in FIG. 29A, the TFT is formed by SAS as shown in FIG. 28B, and the pixel portion and the scanning line side driver circuit are formed on the substrate. In some cases, the signal line side driver circuit is formed as a separate driver IC, and the pixel portion, the signal line side driver circuit, and the scanning line side driver circuit are integrally formed on the substrate as shown in FIG. There are, but any form is acceptable.

  As other external circuit configurations, on the video signal input side, among the signals received by the tuner, the video signal amplification circuit that amplifies the video signal, and the signal output from it corresponds to each color of red, green, and blue And a control circuit for converting the video signal into the input specification of the driver IC. The control circuit outputs signals to the scanning line side and the signal line side, respectively. In the case of digital driving, a signal dividing circuit may be provided on the signal line side and an input digital signal may be divided into m pieces and supplied.

  Of the signals received by the tuner, the audio signal is sent to the audio signal amplifier circuit, and the output is supplied to the speaker via the audio signal processing circuit. The control circuit receives control information of the receiving station (reception frequency) and volume from the input unit, and sends a signal to the tuner and the audio signal processing circuit.

FIG. 23 illustrates an example of a liquid crystal display module. A TFT substrate 2600 and a counter substrate 2601 are fixed to each other with a sealant 2602, and a pixel portion 2603 and a liquid crystal layer 2604 are provided therebetween to form a display region. The colored layer 2605 is necessary for color display. In the case of the RGB method, a colored layer corresponding to each color of red, green, and blue is provided corresponding to each pixel. Polarizing plates 2606 and 2607 and a lens film 2613 are provided outside the TFT substrate 2600 and the counter substrate 2601. The light source is composed of a cold cathode tube 2610 and a reflection plate 2611. The circuit board 2612 is connected to the TFT substrate 2600 by a flexible wiring board 2609, and an external circuit such as a control circuit or a power supply circuit is incorporated. The liquid crystal display module includes TN (Twisted Nematic) mode, IPS (In-Plane-Switching) mode, MVA (Multi-domain Vertical Alignment) mode, ASM (Axial Symmetric).
An aligned micro-cell) mode, an OCB mode, or the like can be used.

  Further, the liquid crystal display device manufactured according to the present invention can have higher performance by using an OCB mode capable of high-speed response. FIG. 44 shows an example in which the OCB mode is applied to the liquid crystal display module of FIG. 23, and is an FS-LCD (Field sequential-LCD). The FS-LCD emits red light, green light, and blue light in one frame period, and each light emission is performed by a light emitting diode or the like, so that a color filter is unnecessary. Therefore, since it is not necessary to arrange color filters of the three primary colors, 9 times as many pixels can be displayed with the same area. On the other hand, since three colors of light are emitted in one frame period, a high-speed response of the liquid crystal is required.

  Since the thin film transistor included in the liquid crystal display device of the present invention can operate at high speed, an OCB mode can be used. The liquid crystal layer in the OCB mode has a so-called π cell structure. The π cell structure is a structure in which the pretilt angles of liquid crystal molecules are aligned in a plane-symmetric relationship with respect to the center plane between the active matrix substrate and the counter substrate. The alignment state of the π cell structure is splay alignment when no voltage is applied between the substrates, and shifts to bend alignment when a voltage is applied. When a voltage is further applied, the bend-aligned liquid crystal molecules are aligned perpendicularly to both substrates, and light is transmitted. In the OCB mode, high-speed response that is about 10 times faster than the conventional TN mode can be realized.

Therefore, the FS mode and the OCB mode can be applied to the liquid crystal display device of the present invention, and a liquid crystal display device and a liquid crystal television with higher performance and higher image quality can be completed. Further, as a mode corresponding to the FS mode, HV-FLC, SS-FLC using a ferroelectric liquid crystal (FLC: Ferroelectric Liquid Crystal), or the like can be used. Typically, a nematic liquid crystal having a relatively low viscosity is used in the OCB mode, and a smectic liquid crystal is used in HV-FLC and SS-FLC. As a liquid crystal material, materials such as FLC, nematic liquid crystal, and smectic liquid crystal are used. Can be used. The liquid crystal display module of FIG. 44 is a transmissive liquid crystal display module, and a red light source 2910a, a green light source 2910b, and a blue light source 2910c are provided as light sources. A control unit 2912 is installed to control on / off of the red light source 2910a, the green light source 2910b, and the blue light source 2910c. The light emission of each color is controlled by the control unit 2912, light enters the liquid crystal, an image is synthesized using time division, and color display is performed.

  In addition, the high-speed optical response speed of the liquid crystal display module is increased by narrowing the cell gap of the liquid crystal display module. The speed can also be increased by reducing the viscosity of the liquid crystal material. The increase in speed is more effective when the pixel in the pixel region of the TN mode liquid crystal display module or the dot pitch is 30 μm or less.

  These liquid crystal display modules can be incorporated into a housing 2001 as shown in FIG. 36A to complete a liquid crystal television device. A main screen 2003 is formed by a liquid crystal display module, and a speaker unit 2009, operation switches, and the like are provided as other accessory equipment. Thus, a liquid crystal television device can be completed according to the present invention.

  A display panel 2002 using a liquid crystal element is incorporated in a housing 2001, and a receiver 2005 receives a general television broadcast and connects to a wired or wireless communication network via a modem 2004 in one direction ( Information communication can also be performed in a bidirectional manner (between the sender and the receiver, or between the sender and the receiver). The operation of the liquid crystal television device can be performed by a switch incorporated in the housing or a separate remote control device 2006, and this remote control device is also provided with a display portion 2007 for displaying information to be output. Also good.

  In addition to the main screen 2003, the liquid crystal television device may be provided with a configuration in which a sub screen 2008 is formed with a second display panel to display channels, volume, and the like. The main screen 2003 and the sub screen 2008 may be formed using a liquid crystal display panel capable of displaying the main screen 2003 and the sub screen with low power consumption. When the present invention is used, a highly reliable liquid crystal display device can be obtained even when such a large substrate is used and a large number of TFTs and electronic components are used.

  FIG. 36B illustrates a television device having a large display portion of 20 to 80 inches, for example, which includes a housing 2010, a display portion 2011, a remote control device 2012 as an operation portion, a speaker portion 2013, and the like. The present invention is applied to manufacture of the display portion 2011. The television set in FIG. 36B is a wall-hanging type and does not require a large installation space.

  Of course, the present invention is not limited to a television device, but can be applied to various uses such as a monitor for a personal computer, an information display board in a railway station or airport, an advertisement display board in a street, etc. can do.

(Embodiment 17)
Various liquid crystal display devices can be manufactured by applying the present invention. That is, the present invention can be applied to various electronic devices in which these liquid crystal display devices are incorporated in a display portion.

  Such electronic devices include video cameras, digital cameras, projectors, head mounted displays (goggles type displays), car navigation systems, car stereos, personal computers, game machines, personal digital assistants (mobile computers, mobile phones, electronic books, etc.) ), An image reproducing apparatus provided with a recording medium (specifically, an apparatus provided with a display capable of reproducing a recording medium such as a digital versatile disc (DVD) and displaying the image). Examples thereof are shown in FIG.

  FIG. 27A illustrates a laptop personal computer which includes a main body 2101, a housing 2102, a display portion 2103, a keyboard 2104, an external connection port 2105, a pointing mouse 2106, and the like. The present invention is applied to manufacturing the display portion 2103. When the present invention is used, a highly reliable high-quality image can be displayed even if the size is reduced and wiring and the like are refined.

  FIG. 27B shows an image reproduction device (specifically, a DVD reproduction device) provided with a recording medium, which includes a main body 2201, a housing 2202, a display portion A 2203, a display portion B 2204, and a recording medium (DVD etc.) reading portion 2205. , An operation key 2206, a speaker portion 2207, and the like. The display portion A 2203 mainly displays image information, and the display portion B 2204 mainly displays character information. The present invention is applied to the production of the display portions A, B 2203, and 2204. When the present invention is used, a highly reliable high-quality image can be displayed even if the size is reduced and wiring and the like are refined.

  FIG. 27C illustrates a mobile phone, which includes a main body 2301, an audio output portion 2302, an audio input portion 2303, a display portion 2304, operation switches 2305, an antenna 2306, and the like. By applying the liquid crystal display device manufactured according to the present invention to the display portion 2304, a highly reliable and high-quality image can be displayed even for a mobile phone that is downsized and wiring and the like are precise.

  FIG. 27D shows a video camera, which includes a main body 2401, a display portion 2402, a housing 2403, an external connection port 2404, a remote control receiving portion 2405, an image receiving portion 2406, a battery 2407, an audio input portion 2408, operation keys 2409, and the like. . The present invention can be applied to the display portion 2402. By applying the liquid crystal display device manufactured according to the present invention to the display portion 2304, a highly reliable and high-quality image can be displayed even with a video camera that is downsized and wiring and the like are made precise. This embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 18)
According to the present invention, a semiconductor device that functions as a wireless chip (also referred to as a wireless processor, a wireless memory, or a wireless tag) can be formed. Applications of wireless chips are wide-ranging. For example, banknotes, coins, securities, bearer bonds, certificates (driver's license, resident card, etc., see FIG. 45A), packaging containers (wrapping paper and 45 (C)), recording medium (DVD software, video tape, etc., see FIG. 45 (B)), vehicles (bicycles, etc., see FIG. 45 (D)), personal items (bags, glasses, etc.) ), Foods, plants, animals, human bodies, clothing, daily necessities, electronic equipment, etc. and goods such as luggage tags (see FIGS. 45E and 45F). be able to. Electronic devices refer to liquid crystal display devices, EL display devices, television devices (also simply referred to as televisions, television receivers, television receivers), mobile phones, and the like.

  The wireless chip is fixed to the article by being attached to the surface of the article or embedded in the article. For example, a book may be embedded in paper, and a package made of an organic resin may be embedded in the organic resin. Forgery can be prevented by providing wireless chips on banknotes, coins, securities, bearer bonds, certificates, etc. In addition, by providing wireless chips in packaging containers, recording media, personal items, foods, clothing, daily necessities, electronic devices, etc., it is possible to improve the efficiency of inspection systems and rental store systems. The wireless chip that can be formed according to the present invention is small, thin, and lightweight because it is provided on a cover material after a thin film integrated circuit formed over a substrate is peeled off by a known peeling process, and is mounted on an article. However, the design is not impaired. Furthermore, since it has flexibility, it can be used for a bottle or pipe having a curved surface.

  Further, by applying a wireless chip that can be formed according to the present invention to an object management or distribution system, it is possible to increase the functionality of the system. For example, by reading the information recorded on the wireless chip provided on the tag with a reader / writer provided on the side of the belt conveyor, information such as the distribution process and delivery destination is read, and inspection of goods and distribution of goods Can be done easily.

    A structure of a wireless chip that can be formed according to the present invention will be described with reference to FIGS. The wireless chip is formed with a thin film integrated circuit 9303 and an antenna 9304 connected thereto. Further, the thin film integrated circuit and the antenna are sandwiched between cover materials 9301 and 9302. The thin film integrated circuit 9303 may be bonded to the cover material with an adhesive. In FIG. 46, one of the thin film integrated circuits 9303 is bonded to a cover material 9301 with an adhesive 9320 interposed therebetween.

  The thin film integrated circuit 9303 is formed using the TFT shown in any of Embodiment Modes 1 to 14, and then peeled off by a known peeling step and provided on the cover material. The semiconductor element used for the thin film integrated circuit 9303 is not limited to this. For example, a memory element, a diode, a photoelectric conversion element, a resistance element, a coil, a capacitor element, an inductor, or the like can be used in addition to the TFT.

  As shown in FIG. 46, an interlayer insulating film 9311 is formed over the TFT of the thin film integrated circuit 9303, and an antenna 9304 connected to the TFT through the interlayer insulating film 9311 is formed. A barrier film 9312 made of a silicon nitride film or the like is formed over the interlayer insulating film 9311 and the antenna 9304.

  The antenna 9304 is formed by discharging a droplet including a conductor such as gold, silver, or copper by a droplet discharge method, followed by drying and baking. By forming the antenna by a droplet discharge method, the number of steps can be reduced, and the cost can be reduced accordingly.

  Cover materials 9301 and 9302 are laminated films (made of polypropylene, polyester, vinyl, polyvinyl fluoride, vinyl chloride, etc.), papers made of fibrous materials, base films (polyester, polyamide, inorganic vapor deposition films, papers, etc.) ) And an adhesive synthetic resin film (acrylic synthetic resin, epoxy synthetic resin, etc.). The laminate film is laminated with the object to be processed by thermocompression bonding. When performing the laminate process, the laminate film is an adhesive layer provided on the outermost surface of the laminate film or a layer provided on the outermost layer. (Not the adhesive layer) is melted by heat treatment and bonded by pressure.

  In addition, by using an incineration-free pollution material such as paper, fiber, and carbon graphite for the cover material, the used wireless chip can be incinerated or cut. Further, wireless chips using these materials are non-polluting because they do not generate toxic gas even when incinerated.

In FIG. 46, the wireless chip is provided on the cover material 9301 through the adhesive 9320. However, instead of the cover material 9301, the wireless chip may be attached to an article for use.

4A and 4B illustrate a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 8A and 8B illustrate a method for manufacturing a liquid crystal display device of the present invention. 4A and 4B illustrate a liquid crystal dropping method that can be applied to the present invention. 4A and 4B illustrate a structure of a liquid crystal display module of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 11 illustrates an electronic device to which the present invention is applied. FIG. 6 is a top view illustrating a liquid crystal display panel of the present invention. FIG. 6 is a top view illustrating a liquid crystal display panel of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 11 illustrates an electronic device to which the present invention is applied. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. The figure which shows the protection circuit to which this invention is applied. FIG. 6 illustrates a liquid crystal display panel of the present invention. FIG. 6 illustrates a liquid crystal display device of the present invention. 4A and 4B illustrate a structure of a liquid crystal display module of the present invention. 1 is a diagram showing a semiconductor device to which the present invention is applied. 1 is a diagram showing a semiconductor device to which the present invention is applied.

Claims (18)

A gate electrode layer and a pixel electrode layer provided on the insulating surface;
A first gate insulating layer on the gate electrode layer;
A second gate insulating layer on the first gate insulating layer;
A third gate insulating layer on the second gate insulating layer;
A crystalline semiconductor layer on the third gate insulating layer;
A semiconductor layer having one conductivity type in contact with the crystalline semiconductor layer;
A source electrode layer and a drain electrode layer in contact with the semiconductor layer having one conductivity;
An insulating layer on the source electrode layer, the drain electrode layer, and the pixel electrode layer;
The insulating layer has a first opening reaching the source electrode layer or the drain electrode layer;
The gate insulating layer and the insulating layer have a second opening reaching the pixel electrode layer;
A wiring layer electrically connecting the source electrode layer or the drain electrode layer and the pixel electrode layer to the first opening and the second opening;
The liquid crystal display device, wherein a thickness of the third gate insulating layer is 0.1 nm or more and 10 nm or less.     The liquid crystal display device according to claim 1, wherein the semiconductor layer having one conductivity includes a metal element. A gate electrode layer and a pixel electrode layer provided on the insulating surface;
A first gate insulating layer on the gate electrode layer;
A second gate insulating layer on the first gate insulating layer;
A third gate insulating layer on the second gate insulating layer;
A crystalline semiconductor layer having a source region and a drain region provided on the third gate insulating layer;
A source electrode layer and a drain electrode layer in contact with the source region and the drain region;
An insulating layer on the source electrode layer, the drain electrode layer, and the pixel electrode layer;
The insulating layer has a first opening reaching the source electrode layer or the drain electrode layer;
The gate insulating layer and the insulating layer have a second opening reaching the pixel electrode layer;
A wiring layer electrically connecting the source electrode layer or the drain electrode layer and the pixel electrode layer to the first opening and the second opening;
The liquid crystal display device, wherein a thickness of the third gate insulating layer is 0.1 nm or more and 10 nm or less.     4. The liquid crystal display device according to claim 3, wherein the source region and the drain region contain a metal element.     5. The liquid crystal display device according to claim 1, further comprising a channel protective layer that selectively covers a channel region of the crystalline semiconductor layer.     6. The first gate insulating layer according to claim 1, wherein the first gate insulating layer is a silicon nitride oxide film, the second gate insulating layer is a silicon oxynitride film, and the third gate insulating layer is nitrided. A liquid crystal display device comprising a silicon film. The gate insulating layer and the insulating layer according to any one of claims 1 to 6, wherein the gate insulating layer and the insulating layer have a third opening that reaches the gate electrode layer.
A liquid crystal display device comprising a gate wiring layer in contact with the gate electrode layer in the third opening.     8. The gate electrode layer and the pixel electrode layer according to claim 1, wherein the gate electrode layer and the pixel electrode layer are one selected from tungsten, molybdenum, zirconia, hafnium, bismuth, niobium, tantalum, chromium, cobalt, nickel, and platinum. A liquid crystal display device comprising a plurality of liquid crystal display devices.     8. The gate electrode layer and the pixel electrode layer according to claim 1, wherein the gate electrode layer and the pixel electrode layer are made of indium tin oxide, indium tin oxide containing silicon oxide, zinc oxide, tin oxide, or an indium zinc oxide alloy. A liquid crystal display device. Having a pixel region and a drive circuit region on the same substrate;
A first gate electrode layer and a second gate electrode layer on the substrate in the drive circuit region;
A first gate insulating layer on the first gate electrode layer and the second gate electrode layer;
A second gate insulating layer on the first gate insulating layer;
A third gate insulating layer on the second gate insulating layer;
A first crystalline semiconductor layer and a second crystalline semiconductor layer on the third gate insulating layer;
An n-type semiconductor layer in contact with the first crystalline semiconductor layer;
A semiconductor layer having a p-type in contact with the first crystalline semiconductor layer;
A first source electrode layer and a first drain electrode layer in contact with the n-type semiconductor layer;
A second source electrode layer and a second drain electrode layer in contact with the p-type semiconductor layer;
A pixel electrode layer on the substrate in the pixel region;
The film thickness of the third gate insulating layer is not less than 0.1 nm and not more than 10 nm,
A liquid crystal display device, wherein a part of the pixel electrode layer is covered with a gate insulating layer.     A liquid crystal television device having a display screen configured by the liquid crystal display device according to claim 1. Forming a gate electrode layer and a pixel electrode layer on the insulating surface;
Forming a gate insulating layer on the gate electrode layer and the pixel electrode layer;
Forming a metal film containing a metal element on the gate insulating layer;
Forming a semiconductor layer on the metal film;
Forming a semiconductor layer having one conductivity type in contact with the semiconductor layer;
Heating the semiconductor layer and the semiconductor layer having one conductivity type;
Forming a source electrode layer and a drain electrode layer in contact with the semiconductor layer having one conductivity type;
Patterning the semiconductor layer having the one conductivity type to form a source region and a drain region;
Forming an insulating layer on the source electrode layer, the drain electrode layer, and the gate insulating layer;
Forming a first opening reaching the source electrode layer or the drain electrode layer in the insulating layer, and a second opening reaching the pixel electrode layer in the insulating layer and the gate insulating layer;
A wiring layer for electrically connecting the source electrode layer or the drain electrode layer and the pixel electrode layer is formed in the first opening and the second opening. Method. Forming a gate electrode layer and a pixel electrode layer on the insulating surface;
Forming a gate insulating layer on the gate electrode layer and the pixel electrode layer;
Forming a semiconductor layer on the gate insulating layer;
Adding a metal element to the semiconductor layer;
Forming a semiconductor layer having one conductivity type in contact with the semiconductor layer;
Heating the semiconductor layer and the semiconductor layer having one conductivity type;
Forming a source electrode layer and a drain electrode layer in contact with the semiconductor layer having one conductivity type;
Patterning the semiconductor layer having the one conductivity type to form a source region and a drain region;
Forming an insulating layer on the source electrode layer, the drain electrode layer, and the gate insulating layer;
Forming a first opening reaching the source electrode layer or the drain electrode layer in the insulating layer, and a second opening reaching the pixel electrode layer in the insulating layer and the gate insulating layer;
A wiring layer for electrically connecting the source electrode layer or the drain electrode layer and the pixel electrode layer is formed in the first opening and the second opening. Method. Forming a gate electrode layer and a pixel electrode layer on the insulating surface;
Forming a gate insulating layer on the gate electrode layer and the pixel electrode layer;
Forming a metal film containing a metal element on the gate insulating layer;
Forming a semiconductor layer on the metal film;
Forming a channel protective layer selectively on the semiconductor layer;
Forming a semiconductor layer having one conductivity type in contact with the semiconductor layer and the channel protective layer;
Heating the semiconductor layer, the channel protective layer, and the semiconductor layer having one conductivity type;
Forming a source electrode layer and a drain electrode layer in contact with the semiconductor layer having one conductivity type;
Patterning the semiconductor layer having the one conductivity type to form a source region and a drain region;
Forming an insulating layer on the source electrode layer, the drain electrode layer, and the gate insulating layer;
Forming a first opening reaching the source electrode layer or the drain electrode layer in the insulating layer, and a second opening reaching the pixel electrode layer in the insulating layer and the gate insulating layer;
A wiring layer for electrically connecting the source electrode layer or the drain electrode layer and the pixel electrode layer is formed in the first opening and the second opening. Method. Forming a gate electrode layer and a pixel electrode layer on the insulating surface;
Forming a gate insulating layer on the gate electrode layer and the pixel electrode layer;
Forming a semiconductor layer on the gate insulating layer;
Forming a channel protective layer selectively on the semiconductor layer;
Adding a metal element to the semiconductor layer and the channel protective layer;
Forming a semiconductor layer having one conductivity type in contact with the semiconductor layer and the channel protective layer;
Heating the semiconductor layer, the channel protective layer, and the semiconductor layer having one conductivity type;
Forming a source electrode layer and a drain electrode layer in contact with the semiconductor layer having one conductivity type;
Patterning the semiconductor layer having the one conductivity type to form a source region and a drain region;
Forming an insulating layer on the source electrode layer, the drain electrode layer, and the gate insulating layer;
Forming a first opening reaching the source electrode layer or the drain electrode layer in the insulating layer, and a second opening reaching the pixel electrode layer in the insulating layer and the gate insulating layer;
A wiring layer for electrically connecting the source electrode layer or the drain electrode layer and the pixel electrode layer is formed in the first opening and the second opening. Method.     16. The metal element according to claim 12, wherein one or more selected from iron, nickel, cobalt, ruthenium, rhodium, palladium, osnium, iridium, platinum, titanium, copper and gold are used as the metal element. A method for manufacturing a liquid crystal display device. The first gate insulating layer is formed on the gate electrode layer and the pixel electrode layer as the gate insulating layer according to any one of claims 12 to 16.
Forming a second gate insulating layer on the first gate insulating layer;
A method for manufacturing a liquid crystal display device, wherein a third gate insulating layer having a thickness of 0.1 nm to 10 nm is formed over the second gate insulating layer. 18. A silicon nitride oxide film is formed as the first gate insulating layer, a silicon oxynitride film is formed as the second gate insulating layer, and a silicon nitride film is formed as the third gate insulating layer according to claim 17. A method for manufacturing a liquid crystal display device.

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