JP2005148766A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active matrix type liquid crystal display device. <P>SOLUTION: This active matrix type liquid crystal device has a backing film formed on a glass substrate, a semiconductor layer formed on the backing film, a gate insulating film formed on the semiconductor layer, a gate electrode formed on the gate insulating film, a silicon nitride film formed on the gate insulating film and gate electrode, a an electrode connected to the semiconductor layer in a 1st contact hole penetrating the gate insulating film and silicon nitride film, an organic resin film formed on the silicon nitride film and electrode, and a pixel electrode connected to the electrode in a 2nd contact hole penetrating the organic resin film, corners of the pixel electrode being rounded. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The invention disclosed in this specification relates to a pixel structure of an active matrix display device (particularly, a liquid crystal display device). More specifically, the present invention relates to a configuration of an auxiliary capacitor and a black matrix (BM) connected in parallel with the pixel electrode.
The present invention also relates to a pixel configuration of a flat panel display that requires a black matrix widely.

  A display device having an active matrix circuit is known. This has a plurality of source wirings for transmitting image data, a plurality of gate wirings arranged so as to intersect therewith and a plurality of gate wirings for transmitting switching signals, and a plurality of pixels provided at the intersections thereof. A transistor (particularly a thin film transistor) is usually used as the switching element.

  The pixel has not only a transistor for switching but also a pixel electrode, and has a structure in which the gate electrode of the transistor is connected to the gate wiring, the source is connected to the source wiring, and the drain is connected to the pixel electrode. Note that in the operation of a transistor, the distinction between a source and a drain is not a steady one and varies according to a signal according to a normal electric circuit definition. However, in the following description, an impurity region provided in a transistor Of these, the one simply connected to the source wiring is called the source, and the one connected to the pixel electrode is called the drain.

  Each pixel has one or more transistors. In particular, the connection of two or more transistors in series is effective because the leakage current can be reduced even when the transistors are not selected. Even in such a case, the above definition is applied, and an impurity region that is not connected to either the source wiring or the pixel electrode is not particularly defined.

  The pixel electrode forms a capacitor (capacitor) between the opposing electrodes across the liquid crystal. The above-described transistor functions as a switching element that takes charge into and out of this capacitor. However, in actual operation, the capacitance is too small with only the pixel electrode portion, and the necessary charge cannot be held for a sufficient time. Therefore, it is necessary to provide an auxiliary capacity separately.

  Conventionally, this auxiliary capacitor (also referred to as a storage capacitor) has been separately provided with an opaque conductive material such as metal, and a capacitor is formed between this auxiliary capacitor and a pixel electrode or a semiconductor layer. Usually, the gate wiring in the next row was used as the counter electrode. However, when the pixel area is large, the capacitance formed using the gate wiring is sufficient, but when the pixel area is small, the capacitance is insufficient with the original gate wiring alone, and the area of the auxiliary capacitor electrode is reduced. In order to secure it, it was required to expand the gate wiring more than necessary. In such a structure, there is a portion that shields light in the pixel, so that the aperture ratio decreases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a pixel structure capable of obtaining a sufficient capacity without a substantial decrease in aperture ratio.

In particular, in an active matrix type liquid crystal display device, a light blocking member called a black matrix is required around the pixel electrode.
In general, in an area where source wirings and gate wirings arranged in a grid pattern are formed, the upper part is raised.

  As a result, the rubbing treatment for the alignment film in this portion does not work well, and the orientation of the liquid crystal molecules in that portion is disturbed. As a result, a phenomenon in which light leaks or light is not sufficiently transmitted appears in the periphery of the pixel. In addition, it is impossible to perform a predetermined electro-optical operation on the liquid crystal in this portion.

When the above phenomenon occurs, the display around the pixel becomes blurry, and the overall sharpness of the image is lost.
As a configuration for solving this problem, there is a configuration in which a light shielding film is disposed so as to cover the edge portion of the pixel electrode. This light shielding film is called a black matrix (BM).

The first invention disclosed in this specification is:
(1) An electrode that covers the source wiring and the gate wiring and shields visible light (it is called a common electrode because it is held at a constant potential) is disposed.
(2) The peripheral portion of the pixel electrode overlaps the common electrode.
(3) The common electrode is connected to a wiring in the same layer as the source wiring through a film in the same layer as the pixel electrode.
It has the characteristics.

  In the above configuration, all regions other than the pixel electrode and part of the source and drain of the transistor can be shielded from incident light by the common electrode. In particular, the source wiring and the gate wiring can be completely shielded from the outside. By doing so, it is possible to prevent electromagnetic waves from entering the source wiring and the gate wiring from the outside and causing malfunction and malfunction of the device.

In addition, an auxiliary capacitor can be formed without causing a decrease in the aperture ratio. This is because the black matrix itself is originally required, and in the present invention, an auxiliary capacitor can be formed in the overlapping portion of the common electrode and the pixel electrode that also function as the black matrix.
In the above configuration, the pixel electrode is formed of a transparent conductive film such as ITO (indium tin oxide). In the basic configuration, one pixel electrode is provided for each pixel, but a configuration in which the pixel electrode is divided into a plurality of pixels may be employed.

The common electrode (black matrix) arranged so as to overlap with the peripheral edge portion of the pixel electrode is made of titanium or chromium. As is apparent from the above description, the common electrode also functions as one electrode constituting the auxiliary capacitance.
For this purpose, it is necessary to connect the common electrode to the outside. In the present invention, the requirement (3) is provided for that purpose. That is, in the requirement (3), a wiring in the same layer as the source wiring is a wiring connected to a bonding portion with an external wiring. However, in a general process, there is no step of directly contacting the common electrode layer and the above wiring. Therefore, in the present invention, the common electrode and the external bonding portion are electrically connected to each other through a film in the same layer as the pixel electrode.

  The common electrode exists through a lower wiring portion and an insulating layer (first insulating layer). In addition, the pixel electrode layer exists via an insulating layer (second insulating layer) separate from the common electrode. Therefore, a contact hole is formed by etching the second insulating layer on the common electrode and on each portion where the common electrode does not exist. Further, the first insulating layer is continuously etched to form a contact hole. In that case, it is desirable that the common electrode is not etched in the latter etching step.

  Through the above steps, a contact hole reaching the common electrode (first contact hole) and a contact hole reaching the lower wiring (second contact hole) are formed. Thereafter, a transparent conductive film is formed and etched in the same process as the formation of the pixel electrode, and a wiring connecting the first contact hole and the second contact hole is constituted by the transparent conductive film. Thus, the common electrode is connected to the external wiring.

The configuration of the second invention is as follows:
(1) A common electrode for shielding light is disposed on the periphery of the pixel electrode.
(3) A film made of the same layer as the pixel electrode and having a film in contact with the common electrode and the wiring of the same layer as the source wiring.
It is characterized by being disposed in the organic resin layer. The operation and effect of the second invention are the same as those described with respect to the first invention.

In the first or second invention, the insulating layer (second insulating layer) between the pixel electrode layer and the common electrode is made of an organic resin such as polyimide so that the surface thereof is flat. Good.
In the first or second invention, the insulating layer (second insulating layer) between the pixel electrode layer and the common electrode may be a high dielectric material. In particular, a material having a dielectric constant higher than that of the insulating layer (first insulating layer) on which the common electrode is formed is preferably used.

  If the dielectric constant of the insulating layer existing between the pixel electrode and the common electrode is higher than the dielectric constant of the organic resin layer formed on the surface of the common electrode, it is natural that the auxiliary capacitance can be increased. In general, since capacitive coupling between wirings is increased, it has been avoided to increase the dielectric constant of an insulating layer in a semiconductor circuit. However, in the present invention, the source wiring and the gate wiring which are main wirings are shielded by the common electrode, and there is no wiring capacitively coupled to the pixel electrode through the insulating layer. Therefore, there is no problem with the insulating layer as a high dielectric material.

  Further, in order to strengthen the bonding, in the first or second invention described above, the portion to be bonded (bonding pad) is made of a film of the same layer as the pixel electrode and a wiring of the same layer as the source wiring. A multilayer structure is preferable.

  By partially overlapping the black matrix covering the periphery of the pixel electrode and the pixel electrode with an insulating film interposed therebetween, that portion can be configured as an auxiliary capacitor. This itself is not a factor that reduces the aperture ratio of the pixel. Further, since the insulating film can be thinned, the capacitance value can be increased.

  The invention disclosed in this specification is not limited to an active matrix liquid crystal electro-optical device, but is generally used for a flat panel display that requires a black matrix covering a pixel electrode and its periphery, and an auxiliary capacitor connected to a thin film transistor. can do. Thus, the present invention is industrially useful.

  1 to 3 show a pixel structure of an active matrix liquid crystal display device using the invention disclosed in this specification. FIG. 1 shows an outline of a manufacturing process sectional view of a TFT portion of a pixel of this embodiment, and FIG. 2 shows an arrangement of each wiring, common electrode, pixel electrode, semiconductor layer and the like of the pixel. A cross section taken along the dotted line XY in FIG. 2A is shown in FIG. 1, but FIG. 1 is conceptual and is not exactly the same as the arrangement in FIG. Further, FIG. 3 is a sectional view of manufacturing steps of the contact portion (interlayer contact region), the external lead terminal (bonded portion, terminal region) and the TFT region of the common electrode and the lower layer wiring of the display device. The numbers in the figures correspond in all figures.

Note that FIGS. 1 to 3 show only the structure on the substrate side where the thin film transistor is arranged, and there is actually a counter substrate (counter substrate), which is shown in FIG. The liquid crystal is held with a gap of several μm between the substrate and the substrate.
Hereinafter, the manufacturing process will be described. As shown in FIG. 1A, a semiconductor layer (active layer) 12 of a transistor is provided on a glass substrate 11 provided with a base silicon oxide film (not shown).

  The active layer 12 is composed of a crystalline silicon film obtained by crystallizing an amorphous silicon film by heating or laser light irradiation. A gate insulating film 13 is formed covering the active layer 12. The material of the gate insulating film 13 is preferably silicon oxide or silicon nitride. For example, a silicon oxide film formed by a plasma CVD method may be used. On the gate insulating film, a gate wiring (gate electrode) 14 is formed of an aluminum-titanium alloy by a known sputtering method. (Fig. 1 (A), Fig. 3 (A))

The circuit arrangement of the pixel portion in this state is shown in FIG. (Fig. 2 (A))
Next, an impurity region 15 is formed by introducing an N-type or P-type impurity into the active layer by a known ion doping method using the gate wiring as a mask. After the introduction of the impurities, if necessary, the impurities may be activated (recrystallization of the semiconductor film) by thermal annealing or laser annealing.
After the above steps, a silicon nitride film (or silicon oxide film) 16 is deposited by plasma CVD. This functions as a first interlayer insulator. (Fig. 1 (B), Fig. 3 (B))

Next, a contact hole reaching the impurity region 15 is formed in the first interlayer insulator 16. Then, a multilayer film of titanium and aluminum is formed by a known sputtering method, and this is etched to form a source wiring 17a, a drain electrode 17b, and a wiring 17c connected to the bonding pad. In FIG. 3, the wiring 17c is shown in both the terminal region and the interlayer contact region, but this is the same.
After the above steps, a silicon nitride film (or silicon oxide film) 18 is deposited by plasma CVD. This functions as a second interlayer insulator. (Fig. 1 (C), Fig. 3 (C))

The circuit arrangement of the pixel portion in this state is shown in FIG. (Fig. 2 (B))
Next, a chromium film is formed by a known sputtering method, and this is etched to form the common electrode 22. Titanium may be used in addition to chromium.
The circuit arrangement of the pixel portion in this state is shown in FIG. As can be seen from the figure, the common electrode is formed so as to cover the source wiring and the gate wiring. (Fig. 2 (C))

  Further, an organic resin layer 20 of polyimide is formed by a spin coating method. The thickness needs to be larger than the thickness of the common electrode, but is typically 0.5 to 1 μm. In this case, the thickness on the common electrode can be 0.3 μm or more. Then, contact holes 21 are formed in the organic resin layer. Here, the contact hole 21a forms a contact for connecting the pixel electrode and the TFT. Moreover, the contact hole 21b is an opening part of the part to bond. Further, the contact holes 21c and 21d are contact holes for providing a wiring for connecting the common electrode of the present invention and the lower layer wiring. (Fig. 1 (D), Fig. 3 (D))

Further, the etching is advanced, and the second interlayer insulating film 18 is also etched. By this step, the lower wiring 17 is reached in the contact holes 21a, 21b and 21d. However, in the contact hole 21c, the common electrode 19 serves as an etching stopper, and etching does not proceed further.
Next, an ITO film is formed by a known sputtering method, and this is etched to form pixel electrodes 22a, 22b and 22c, a protective film 22d on the surface of the bonding portion, and an interlayer connection wiring 22e.

  The pixel electrode 22c is a pixel electrode of the transistor, and the pixel electrodes 22a and 22b are adjacent pixel electrodes. In this embodiment, the protective film 22d is in contact with only the wiring 17c, and the interlayer connection wiring 22e is in contact with only the wiring 17c and the common electrode 19.

  Capacitors 23 a, 23 b, and 23 c are formed on the portions where the pixel electrodes 22 a to 22 b overlap with the common electrode 19 through the organic resin layer 20. A bonding wiring 24 is connected to the contact hole 21b (bonding pad). In this portion, the wiring 17c and the protective film 22d of the transparent conductive film are provided in multiple layers, and since the surface of the protective film 22d is not deteriorated by the outside air, stable bonding can be performed at any time. (Fig. 1 (E), Fig. 3 (E))

  The circuit arrangement of the pixel portion in this state is shown in FIG. In the drawing, the pixel electrode and the position of the overlapping portion of the pixel electrode and the common electrode (that is, the portion where the capacitance exists) are shown by shading for easy understanding. As can be seen from the figure, the pixel electrode is formed so as to overlap the common electrode, and the common electrode functions as a black matrix. For example, it is possible to prevent the generation and accumulation of charges due to irradiation with strong light.

Further, the common electrode 19 functions not only as a light shield but also as a shield against an electromagnetic wave from the outside. In other words, the gate wiring 14 and the source wiring 17a have a function of preventing unnecessary signal intrusion due to the antenna. (Fig. 2 (D))
As is clear from FIG. 2C, the common electrode 19 is disposed so as to cover the channel of the thin film transistor. This is to prevent the operation of the thin film transistor from being affected by light.

  Here, a configuration in which the organic resin layer 20 is a single layer is shown, but a multilayer structure may be used. Moreover, you may comprise with an inorganic material or a material with a higher dielectric constant. This is because there is no capacitive coupling between the pixel electrode and the lower wiring through the insulating layer corresponding to the organic resin layer. If the insulating layer corresponding to the organic resin layer 20 is made of a high dielectric material, it is effective in increasing the auxiliary capacitance.

The manufacturing process sectional drawing of one Example of this invention is shown. An arrangement of wiring and the like in the embodiment is shown. The manufacturing process sectional drawing of an Example is shown.

Explanation of symbols

11 Glass substrate 12 Active layer 13 Gate insulating film 14 Gate wiring (gate electrode)
DESCRIPTION OF SYMBOLS 15 Impurity area | region 16 1st interlayer insulator 17 Source wiring and its same layer wiring 18 2nd interlayer insulator 19 Common electrode
20 Organic Resin Layer 21 Contact Hole 22 Pixel Electrode and Same Layer Wiring 23 Auxiliary Capacitor 24 Bonded Wiring

Claims (44)

An organic resin film, and a pixel electrode formed on the organic resin film,
A corner portion of the pixel electrode has a rounded shape. An organic resin film, and a pixel electrode made of a transparent conductive film formed on the organic resin film,
A corner portion of the pixel electrode has a rounded shape. An organic resin film, and a pixel electrode made of ITO formed on the organic resin film,
A corner portion of the pixel electrode has a rounded shape. An organic resin film, and a pixel electrode formed on the organic resin film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. An organic resin film, and a pixel electrode made of a transparent conductive film formed on the organic resin film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. An organic resin film, and a pixel electrode made of ITO formed on the organic resin film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. An organic resin film having a thickness of 0.3 μm or more, and a pixel electrode formed on the organic resin film,
A corner portion of the pixel electrode has a rounded shape. An organic resin film having a thickness of 0.3 μm or more, and a pixel electrode made of a transparent conductive film formed on the organic resin film,
A corner portion of the pixel electrode has a rounded shape. An organic resin film having a thickness of 0.3 μm or more, and a pixel electrode made of ITO formed on the organic resin film,
A corner portion of the pixel electrode has a rounded shape. An organic resin film having a thickness of 0.3 μm or more, and a pixel electrode formed on the organic resin film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. An organic resin film having a thickness of 0.3 μm or more, and a pixel electrode made of a transparent conductive film formed on the organic resin film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. An organic resin film having a thickness of 0.3 μm or more, and a pixel electrode made of ITO formed on the organic resin film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An organic resin film formed on the silicon nitride film and the electrode;
A pixel electrode connected to the electrode in a second contact hole penetrating the organic resin film,
A corner portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An organic resin film formed on the silicon nitride film and the electrode;
A pixel electrode made of a transparent conductive film connected to the electrode in a second contact hole penetrating the organic resin film,
A corner portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An organic resin film formed on the silicon nitride film and the electrode;
A pixel electrode made of ITO connected to the electrode in a second contact hole penetrating the organic resin film,
A corner portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An organic resin film formed on the silicon nitride film and the electrode;
A pixel electrode connected to the electrode in a second contact hole penetrating the organic resin film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An organic resin film formed on the silicon nitride film and the electrode;
A pixel electrode made of a transparent conductive film connected to the electrode in a second contact hole penetrating the organic resin film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An organic resin film formed on the silicon nitride film and the electrode;
A pixel electrode made of ITO connected to the electrode in a second contact hole penetrating the organic resin film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape.   19. The liquid crystal display device according to claim 13, wherein the organic resin film has a thickness of 0.3 μm or more.   20. The semiconductor layer according to claim 13, wherein the semiconductor layer has an impurity region in a region that does not overlap the gate electrode, and an end portion of the impurity region substantially coincides with an end portion of the gate electrode. A liquid crystal display device.   21. The liquid crystal display device according to claim 1, wherein the organic resin film is polyimide.   The liquid crystal display device according to claim 1, wherein the organic resin film is formed by a spin coating method. An insulating film having a flat surface, and a pixel electrode formed on the insulating film having a flat surface,
A corner portion of the pixel electrode has a rounded shape. An insulating film having a flat surface, and a pixel electrode made of a transparent conductive film formed on the flat insulating film,
A corner portion of the pixel electrode has a rounded shape. An insulating film having a flat surface, and a pixel electrode made of ITO formed on the flat insulating film;
A corner portion of the pixel electrode has a rounded shape. An insulating film having a flat surface, and a pixel electrode formed on the insulating film having a flat surface,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. An insulating film having a flat surface, and a pixel electrode made of a transparent conductive film formed on the flat insulating film,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. An insulating film having a flat surface, and a pixel electrode made of ITO formed on the flat insulating film;
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape.
An insulating film having a flat surface with a thickness of 0.3 μm or more, and a pixel electrode formed on the insulating film having a flat surface;
A corner portion of the pixel electrode has a rounded shape. An insulating film having a flat surface with a thickness of 0.3 μm or more, and a pixel electrode made of a transparent conductive film formed on the insulating film having a flat surface,
A corner portion of the pixel electrode has a rounded shape. An insulating film having a flat surface with a thickness of 0.3 μm or more, and a pixel electrode made of ITO formed on the insulating film having a flat surface;
A corner portion of the pixel electrode has a rounded shape. An insulating film having a flat surface with a thickness of 0.3 μm or more, and a pixel electrode formed on the insulating film having a flat surface;
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. An insulating film having a flat surface with a thickness of 0.3 μm or more, and a pixel electrode made of a transparent conductive film formed on the insulating film having a flat surface,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. An insulating film having a flat surface with a thickness of 0.3 μm or more, and a pixel electrode made of ITO formed on the insulating film having a flat surface;
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An insulating film having a flat surface formed on the silicon nitride film and the electrode;
A pixel electrode connected to the electrode in a second contact hole having a flat surface penetrating an insulating film;
A corner portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An insulating film having a flat surface formed on the silicon nitride film and the electrode;
A pixel electrode made of a transparent conductive film connected to the electrode in a second contact hole penetrating the insulating film having a flat surface,
A corner portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An insulating film having a flat surface formed on the silicon nitride film and the electrode;
A pixel electrode made of ITO connected to the electrode in a second contact hole penetrating the insulating film having a flat surface;
A corner portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An insulating film having a flat surface formed on the silicon nitride film and the electrode;
A pixel electrode connected to the electrode in a second contact hole having a flat surface penetrating an insulating film;
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An insulating film having a flat surface formed on the silicon nitride film and the electrode;
A pixel electrode made of a transparent conductive film connected to the electrode in a second contact hole penetrating the insulating film having a flat surface,
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape. A base film formed on a glass substrate;
A semiconductor layer formed on the base film;
A gate insulating film formed on the semiconductor layer;
A gate electrode formed on the gate insulating film;
A silicon nitride film formed on the gate insulating film and the gate electrode;
An electrode connected to the semiconductor layer in a first contact hole penetrating the gate insulating film and the silicon nitride film;
An insulating film having a flat surface formed on the silicon nitride film and the electrode;
A pixel electrode made of ITO connected to the electrode in a second contact hole penetrating the insulating film having a flat surface;
The liquid crystal display device according to claim 1, wherein an end portion of the pixel electrode has a rounded shape.   41. The liquid crystal display device according to claim 35, wherein the insulating film having a flat surface has a thickness of 0.3 [mu] m or more.   45. The semiconductor device according to claim 35, wherein the semiconductor layer has an impurity region in a region that does not overlap with the gate electrode, and an end portion of the impurity region substantially coincides with an end portion of the gate electrode. A characteristic liquid crystal display device.   43. The liquid crystal display device according to claim 23, wherein the insulating film having a flat surface is polyimide.   44. The liquid crystal display device according to claim 23, wherein the insulating film having a flat surface is formed by a spin coating method.

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