KR0182019B1 - Liquid crystal cell and its manufacturing method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal cell and a method of manufacturing the same. In particular, in order to planarize a thin film transistor substrate and a common electrode substrate of a liquid crystal cell, a step of using a spin on glass (SOG) with a protective film is overcome. It relates to a liquid crystal cell.

Therefore, it is possible to realize low reflection by overcoming the disadvantage of deterioration of image quality due to external light, and to overcome the disadvantage that the vertical viewing angle asymmetrically generated due to the positive optical anisotropy of the liquid crystal is made by making the optical anisotropy of the compensation film negative. Can be.

Description

Liquid crystal cell and its manufacturing method

1 is a cross-sectional view showing a substrate of a thin film transistor of a conventional liquid crystal cell,

2 is a cross-sectional view showing a common electrode substrate of a conventional liquid crystal cell,

3 is a cross-sectional view (a) to (g) illustrating a conventional method for manufacturing a thin film transistor substrate of another liquid crystal cell according to a process sequence,

4 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a first embodiment of the present invention.

5 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a second exemplary embodiment of the present invention.

6 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a third exemplary embodiment of the present invention.

7 is a cross-sectional view illustrating a method of manufacturing a thin film transistor substrate of a liquid crystal cell according to a fourth embodiment of the present invention according to a process sequence;

8 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a fifth embodiment of the present invention.

9 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a sixth embodiment of the present invention.

10 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a seventh embodiment of the present invention.

11 is a cross-sectional view illustrating a method of manufacturing a thin film transistor substrate of a liquid crystal cell according to an eighth embodiment of the present invention according to a process sequence;

12 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a ninth embodiment of the present invention.

13 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a tenth embodiment of the present invention.

14 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to an eleventh embodiment of the present invention.

FIG. 15 is a cross-sectional view (a) to (c) illustrating a method of manufacturing a common electrode substrate of a liquid crystal cell according to a twelfth embodiment of the present invention according to a process sequence;

FIG. 16 is a cross-sectional view illustrating a common electrode substrate of a liquid crystal cell according to a thirteenth embodiment of the present invention.

17 is a cross-sectional view illustrating a common electrode substrate of a liquid crystal cell according to a fourteenth exemplary embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal cell and a method for manufacturing the same. In particular, a liquid crystal that overcomes a step using a spin on glass (SOG) coating method for planarization of a thin film transistor substrate and a common electrode substrate of a liquid crystal cell. A cell and a method of manufacturing the same.

In general, the liquid crystal cell has the following structure. A common electrode substrate including a substrate, three color filter layers of red, green, and blue, and a common electrode, a plurality of pixels, a gate line for transmitting image information signals to the pixels, and an intersection portion of the data line and the gate line. A thin film transistor substrate including a switching element, and a liquid crystal filled between the thin film transistor substrate and the rigid common electrode substrate.

First, a thin film transistor substrate of a conventional liquid crystal cell will be described with reference to the drawings.

1 is a cross-sectional view showing a thin film transistor substrate of a conventional liquid crystal cell. As shown in FIG. 1, a thin film transistor substrate of a liquid crystal cell includes a substrate 1, a gate electrode 2 formed on the substrate 1, and a gate oxide film formed on the gate electrode 2. (4), an insulating film 6 formed on the gate oxide film 4, a semiconductor film 8 formed on the insulating film 6, and an exogenous semiconductor film formed on the semiconductor film 8 (10), the source / drain electrodes 12 formed on the exogenous semiconductor film 10, the protective film 14 formed on the source / drain electrodes 12, and the protective film 14 formed thereon. And the exogenous semiconductor film 10 and the source / drain electrode 12 are patterned to expose the semiconductor film 8 formed on the gate electrode 2. The pixel electrode 16 is the source / drain electrode 12 It is to be connected.

In this case, the gate electrode 2 may be formed of aluminum (A1), the gate oxide film 4 may be formed of an aluminum oxide film (A ₂ O ₃ ), and the insulating film 6 may be formed of a silicon insulating film (SiNｘ). The semiconductor film 8 may be formed of amorphous silicon (a-Si), and the exogenous semiconductor film 10 may be formed of n-type amorphous silicon (n ⁺ a-Si). The pixel electrode 16 may be formed of indium tinoxide (ITO).

The thin film transistor substrate of the liquid crystal cell may be divided into a thin film transistor unit (1) having a gate electrode 2 and a source / drain electrode 12 formed therein, and a pixel electrode unit (2) occupying most of the pixel electrode. .

However, the conventional thin film transistor substrate has a disadvantage due to the step difference due to the generation of the topology (g) between the thin film transistor unit (X1) and the pixel electrode unit (X2). That is, the cell gap is uneven. In addition, the screen display may be defective, and the alignment process may not be performed during the rubbing process in which the liquid crystal molecules are rubbed with a cloth to align the liquid crystal molecules in one direction on the surface of the alignment film, which is a polymer material. Stress concentration in the cracks are likely to occur.

Thus, a screen display failure occurs. Meanwhile, a common electrode substrate of a conventional liquid crystal cell will be described with reference to the drawings. 2 is a cross-sectional view showing a common electrode substrate of a conventional liquid crystal cell. As shown in FIG. 2, the common electrode substrate of the liquid crystal cell includes a color filter layer 104 in which a red filter layer, a green filter layer, and a blue filter layer are repeatedly arranged on a substrate 101 made of a transparent insulating material to form a color display. Is formed.

At this time, each filter layer 104 having a predetermined width g1 is arranged at a constant interval g2. The passivation layer 106 is formed on the color filter layer 104, and is formed of the common electrode 108 made of a transparent conductive material on the passivation layer 106.

The common electrode substrate of the conventional liquid crystal cell has the following disadvantages. In the common electrode substrate of the conventional liquid crystal cell, red (R), green, and blue color filters are formed at regular intervals, so that the color filter is formed and the color filter on the substrate is formed. The step is generated in the part that is not present, the disadvantage is caused by the step.

Therefore, in order to overcome the step (g), a protective film is formed using a thermosetting resin between a portion where the killer filter is formed and a portion where the color filter on the substrate is not formed.

However, the thermosetting resin adversely affects pixel electrode formation, which is a subsequent process. That is, an outgassing phenomenon occurs from the thermosetting resin to increase the resistance of the pixel electrode and decrease the current to deteriorate the characteristics of the pixel electrode.

In addition, the thermosetting resin has a bad effect in the heat treatment process for the purpose of reducing the resistance of the pixel electrode, which is a subsequent process. That is, the thermosetting resin thermally expands to cause wrinkles in the pixel electrode and the protective film, thereby decreasing transmittance and color reproducibility.

Therefore, a thin film transistor of another conventional liquid crystal cell has emerged to compensate for the shortcomings of the thin film transistor substrate of the conventional liquid crystal cell. Structure and manufacturing method of a thin film transistor substrate of another conventional liquid crystal cell

It demonstrates with reference to FIG.3 (a)-(g). (A)-(g) of FIG. 3 is sectional drawing which shows the manufacturing method of the thin film transistor substrate of another conventional liquid crystal cell according to a process sequence.

As shown in FIG. 3A, a gate wiring metal film is deposited and patterned on the transparent insulating substrate 1 to form the gate electrode 2.

As shown in FIG. 3B, anodization is performed to form a gate oxide film 4 on the gate electrode 2. As shown in FIG.

Next, as shown in FIG. 3C, the gate insulating film 6 is deposited, and the semiconductor film 8 and the exogenous semiconductor film 10 are sequentially deposited on the gate insulating film 6 on the gate electrode 2. do.

As shown in FIG. 3D, the semiconductor film 8 and the exogenous semiconductor film 10 are patterned to form a semiconductor pattern.

As shown in FIG. 3E, the source and drain electrodes 12 are formed to overlap both edges of the exogenous semiconductor film 12, and the exogenous semiconductor film ( Remove the exposed part of 12).

As shown in FIG. 3 (f), a SOG (spin on glass) film 20 is applied over the entire surface to eliminate the step difference caused by the wirings, and the SOI film is exposed so that a part of the drain electrode 12 is exposed. (20) Remove some.

As shown in (g) of FIG. 3, the transparent pixel electrode 16 covering the SOG film 20 is formed.

The thin film transistor substrate of the conventional liquid crystal cell formed by the method shown in FIG. 3 is advantageous in reducing the step difference than the structure described with reference to FIG. 1 above, but uses only the SOG film 20 as the planarization layer. There is a problem that it is difficult to secure the characteristics of the thin film transistor because contamination is likely to occur.

The present invention is to solve the problems of the prior art and to provide a liquid crystal cell and a method of manufacturing the same, which does not adversely affect subsequent processes and can realize planarization of a thin film transistor substrate and a common electrode substrate of a liquid crystal cell.

The thin film transistor substrate of the liquid crystal cell of the present invention for achieving the above object comprises a substrate made of a transparent insulating material, a gate electrode formed of a metal on the substrate, a first insulating film formed on the gate electrode, the first 1, a semiconductor film formed over the insulating film, a source / drain electrode formed over the semiconductor film so as to expose the semiconductor film at a position corresponding to the gate electrode, a protective film formed over the source / drain electrode, and formed over the protective film. And a pixel electrode formed on the SOG film to remove the step, and connected to the / drain electrodes.

On the other hand, another configuration of the thin film transistor substrate of the liquid crystal cell of the present invention for achieving the above object is a substrate made of a transparent material, a gate electrode formed of a metal on the substrate, a first insulating film formed on the gate electrode, A semiconductor film formed on the first insulating film, an etch stopper insulating film formed on a portion corresponding to the gate electrode on the semiconductor film, and an etch stopper insulating film on a portion corresponding to the gate electrode, to be exposed. A source / drain electrode, which is a metal layer, an SOG film that eliminates a step formed on the source / drain electrode, and a pixel electrode formed on the SOG film and connected to the source / drain electrode.

In addition, the configuration of the common electrode substrate of the liquid crystal cell of the present invention for achieving the above object is a substrate made of a transparent insulating material, a color filter layer formed on the substrate, a multilayer wiring on the substrate formed on the color filter layer And a common electrode organ of the liquid crystal cell, characterized in that the SOG film is made to have a uniform film thickness, and a pixel electrode formed on the SOG film. And the configuration of the method for manufacturing a thin film transistor substrate of the liquid crystal cell of the present invention for achieving the above object, the first step of forming a gate electrode 2 of metal on a substrate made of a transparent insulating material, the upper portion of the gate electrode A second step of oxidizing to form an insulating film, a third step of sequentially forming a first insulating film, a semiconductor film, and an exogenous semiconductor film on the gate oxide film in sequence, and a source / drain electrode to expose the semiconductor film at a position corresponding to the gate electrode Forming a protective film on the source / drain electrodes, applying a SOG film that eliminates a step on the protective film by a spin method, and then forming a protective film on the source / drain electrodes together with the protective film to expose a part of the source / drain electrodes. The sixth step of patterning / connecting the source / drain electrode with a transparent conductive material on the SOG film It comprises a seventh step of forming an electrode.

In addition, the configuration of the method for manufacturing a thin film transistor substrate of the liquid crystal cell of the present invention for achieving the above object, the first step of forming a gate electrode with a metal on a substrate made of a transparent insulating material, a first insulating film, a semiconductor on the gate electrode A second step of successively forming a film, an etch stopper insulating film in sequence, a third step of patterning the etch stopper insulating film, a fourth step of sequentially forming a source / drain electrode as a metal layer on the etch stopper insulating film, and the / drain A fifth step of patterning the source / drain electrodes so that a portion of the etch stopper insulating layer is exposed, and a part of the source / drain electrodes is exposed after applying an SOG film on the source / drain electrodes to eliminate the step by a spin method And a sixth step of patterning the source / drain electrodes with a transparent conductive material on the SOG film. Connection to be made up of the seventh step of forming a pixel electrode.

In addition, another configuration of the method for manufacturing a thin film transistor substrate of a liquid crystal cell of the present invention for achieving the above object, the first step of forming a gate electrode of metal on a substrate made of a transparent insulating material, by oxidizing the upper portion of the gate electrode A second step of forming an insulating film, a third step of sequentially forming a first insulating film, a semiconductor film, and an etch stopper insulating film sequentially on the gate oxide film, a fourth step of patterning the etch stopper insulating film, and a portion covered by the etch stopper insulating film A fifth step of forming an exogenous semiconductor layer by ion implantation of impurities into the semiconductor layer except for the above, a sixth step of forming a source / drain electrode on the exogenous semiconductor layer to expose a part of the exogenous semiconductor layer, and the / drain electrode A seventh step of forming a protective film thereon, and a SOG film to remove the step on the protective film And an eighth step of patterning a portion of the source / drain electrode to be exposed after coating by a fin method, and a ninth step of forming a pixel electrode on the SOG film to be connected to the source / drain electrode with a transparent conductive material.

On the other hand, the configuration of the manufacturing method of the common electrode substrate of the liquid crystal cell of the present invention for achieving the above object is a first step of forming a color filter on a substrate made of a transparent insulating material, the multi-layer wiring on the substrate on the color filter A second step of applying a SOG film by a spin method so that the thickness of the film is uniform, and a third step of forming a pixel electrode of a transparent conductive material on the SOG film.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

First, FIG. 4 is a cross-sectional view of a thin film transistor substrate of a liquid crystal cell according to a first embodiment of the present invention, and shows a structure in which a protective film is formed between the source and drain electrodes and the planarization film.

As shown in FIG. 4, the gate electrode 2 is formed on the board | substrate 1, and the gate oxide film 4 is formed in the outer surface of the gate electrode 2. As shown in FIG.

The gate insulating film 6 is covered over the whole surface, the semiconductor film 8 is formed on the gate insulating film 6 on the gate electrode 2, and the source / drain is overlapped with the edge of the semiconductor film 8. The electrode 12 is formed. An exogenous semiconductor film 10 is formed between the source / drain electrodes 12 and the semiconductor film 8 to improve the electrical contact between the metal material and the semiconductor material.

The passivation layer 14 covers the gate insulating layer 6 on which the source / drain electrodes 12 are formed, and a step on which the gate electrode 2, the source / drain electrode 12, etc. are formed on the passivation layer 14. The SOG film 20, which is a planarization film, is covered to make the large part flat with the other parts.

The SOG film 20 and the gate insulating film 6 are provided with contact holes for exposing the drain electrode 12, and the pixel electrode 16 contacting the drain electrode 12 through the contact hole is the SOG film 20. It is formed on the top.

A thin film transistor substrate having the structure of FIG. 4 is manufactured as follows. A gate electrode 2 is formed of a metal (eg, aluminum) on a substrate 1 made of a transparent insulating material, and then an upper portion of the gate electrode 2 is oxidized to form an insulating film (eg, Al ₂ O ₃ ). Thus, the gate oxide film 4 is formed.

Next, SiN 증착 is deposited on the gate oxide film 4 as the first insulating film 6, an a-Si (amorphous silicon) film is used as the semiconductor film 8, and n ⁺ a-Si is used as the exogenous semiconductor film 12 in succession. After patterning to form a semiconductor pattern, the source / drain electrodes 12 are formed on the exogenous semiconductor film 10 so that the exogenous semiconductor film 10 and the semiconductor film 8 at positions corresponding to the gate electrodes 2 are exposed. do.

Next, the exogenous semiconductor film 10 exposed as the source / drain electrode 12 is removed, and then a protective film 14 covering the source / drain electrode 12 is formed.

Next, the SOG 20 film is uniformly coated with a spin method of about 0.8 μm so that the thickness of the multi-layer wired film on the substrate 1 is uniform. Then, the temperature is 200 ° C. using a bake oven or a hot plate. Heat 60 minutes at.

Next, the pixel electrode 16 is formed of a transparent conductive material on the SOG 20 film. As described above, in the first embodiment, since the protective film 14 is further formed before the SOG film 20 is formed only, carbon contamination, which is likely to occur when only the SOG film 20 is formed, can be prevented, thereby improving the characteristics of the transistor. It can be secured.

After the SOG film 20 is formed, a dry etch back process using an F-based reaction gas may be further performed to reduce the thickness of the SOG film.

5 and 6 show the structures of the second and third embodiments which have a relatively thin thickness SOG film by this process, thereby preventing the holding capacitance value from being reduced by the SOG film.

5 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a second embodiment of the present invention, and the basic structure thereof is similar to that of the first embodiment described in FIG. However, the thickness of the SOG film 20 is about 0.2 μm thinner than that of the SOG film 20 in the first embodiment, and the thickness of the SOx film 20 around the pixel electrode 16 is about 0.5 μm or less.

6 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a third exemplary embodiment of the present invention, in which the protective layer 14 is not present, and as in the second exemplary embodiment, the SOG 20 of the pixel electrode 16 is formed. ) The thickness is about 0.5 μm.

Next, embodiments in which the planarization film structure and the planarization method described above are applied to an etch stopper type thin film transistor substrate will be described below. 7 (a) to 7 (i) are cross-sectional views illustrating a method of manufacturing a thin film transistor substrate of a liquid crystal cell according to a fourth embodiment of the present invention in order of process.

First, as shown in FIG. 7A, a gate electrode 2 is formed of a metal (for example, aluminum) on a substrate 1 made of a transparent insulating material.

Next, as shown in Fig. 7B, the upper portion of the gate electrode 2 is oxidized to form a gate oxide film 4 as an insulating film.

Next, as shown in FIG. 7C, SiNｘ is deposited on the gate oxide film 4 to form a first insulating film 6, and a second insulating film 22 for forming an a-Si film and an etch stopper. Are deposited in succession.

Next, as shown in FIG. 7D, the a-Si film is patterned to form the semiconductor film 8, and the second insulating film 22 is patterned to form the etch stopper insulating film 22. Next, as shown in FIG. 7E, the n ⁺ ASI film 10 for forming the exogenous semiconductor film 10 and the metal layer 12 for forming the source / drain electrodes are successively formed on the etch stopper insulating film 22. Deposit.

Next, as shown in FIG. 7F, the metal layer 12 for forming the source / drain electrodes is patterned so that a part of the etch stopper insulating film 22 is exposed to form the source / drain electrodes 12.

Next, as shown in Fig. 7G, the exogenous semiconductor film 12 is removed so that a part of the etch stopper insulating film 22 is exposed.

Next, as shown in Fig. 7H, the SOG 20 film is applied by the spin method so that the thickness of the multi-layered film on the substrate 1 on the source / drain electrode 12 is uniform.

At this time, the SOG 20 film thickness is increased by the step difference increase due to the formation of the etch stopper insulating film 22. Next, as shown in FIG. 7I, the pixel electrode 16 is formed of a transparent conductive material on the SOG 20 film.

8 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a fifth exemplary embodiment of the present invention.

As shown in FIG. 8, the protective film 14 is formed between the source / drain electrode 12 and the SOG 20 film to reduce carbon contamination, thereby securing the characteristics of the thin film transistor.

9 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a sixth embodiment of the present invention, and FIG. 10 is a cross-sectional view showing a thin film transistor substrate of a liquid crystal cell according to a seventh embodiment of the present invention.

The sixth and seventh embodiments shown in FIGS. 9 and 10 are almost similar to the structures and manufacturing methods of the fourth and fifth embodiments mentioned in FIGS. 7 and 8, respectively. However, the sixth and seventh practical examples further include a dry etch back process for reducing the thickness of the SOG 20 after the SOG 20 film is formed.

The following describes the eighth to eleventh embodiments of the present invention, wherein the exogenous semiconductor film is formed on the surface of the semiconductor film by an ion doping method.

11A to 11H are cross-sectional views illustrating a method of manufacturing a thin film transistor substrate of a liquid crystal cell according to an eighth embodiment of the present invention according to a process sequence.

First, as shown in FIG. 11A, the gate electrode 2 is formed of metal on the substrate 1 made of a transparent insulating material.

Next, as shown in FIG. 11B, the upper portion of the gate electrode 2 is oxidized to form a gate oxide film 4.

Next, as shown in FIG. 11C, the first insulating film 6, the semiconductor film 8, and the etch stopper insulating film 22 are successively formed on the gate oxide film 4 in sequence.

Thereafter, the etch stopper insulating film 22 is exposed to silver back by self matching.

Next, as shown in Fig. 11D, the etch stopper insulating film 22 is patterned.

Next, as shown in FIG. 11E, the P-type impurity is ion-implanted into the semiconductor layer except for the portion covered by the etch stopper insulating film 22 to form the exogenous semiconductor layer 11.

Next, as shown in FIG. 11F, a source / drain electrode 12 is formed on the exogenous semiconductor layer 11 so that a part of the exogenous semiconductor layer 11 is exposed.

Next, as shown in (g) of FIG. 11, the SOG 20 film is applied by the spin method so that the thickness of the multi-layered film on the substrate 1 on the source / drain electrode 12 is uniform.

Next, as shown in FIG. 11, on the SOG 20 film, a pixel electrode 16 electrically connected to the drain electrode 12 is formed of a transparent conductive material.

12 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a ninth embodiment of the present invention, and has a structure similar to that of the eighth embodiment.

However, as shown in FIG. 12, before the SOG film 20 is formed, the step of forming the protective film 14 on the source / drain electrodes 12 and the etch stopper insulating film 22 is further included. It can prevent carbon pollution.

FIG. 13 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to a tenth embodiment of the present invention, and FIG. 14 is a cross-sectional view illustrating a thin film transistor substrate of a liquid crystal cell according to an eleventh embodiment of the present invention.

As shown in Figs. 13 and 14, the structure and its manufacturing method are the same except for the structure of the SOG film 20 and its manufacturing method.

As shown in FIGS. 13 and 14, an etch process for reducing the thickness of the SOG film 20 may be further included.

The structure and manufacturing method of the planarized common electrode substrate will be described below.

(A)-(c) of FIG. 15 are sectional drawing which showed the manufacturing method of the common electrode substrate of the liquid crystal cell which concerns on 12th Embodiment of this invention according to a process sequence.

First, as shown in Fig. 15A, a color filter 104 is formed on a substrate 101 made of a transparent insulating material.

Next, as shown in FIG. 15B, the SPG film 120 is applied by the spin method so that the thickness of the multi-layered film on the substrate 101 on the color filter 104 becomes uniform.

Next, as shown in FIG. 15C, the pixel electrode 108 is formed of a transparent conductive material on the SOG 20 film.

FIG. 16 is a cross-sectional view illustrating a common electrode substrate of a liquid crystal cell according to a thirteenth embodiment of the present invention.

As shown in FIG. 16, a space for forming the black matrix 102 may be further included between the filters of the color filter 104 layer on the substrate 101.

17 is a cross-sectional view illustrating a common electrode substrate of a liquid crystal cell according to a fourteenth embodiment of the present invention.

As shown in FIG. 17, the method may further include forming a black matrix 102 on the pixel electrode 108 corresponding to the filters of the color filter 104 layer.

The common electrode substrate according to the twelfth to fourteenth embodiments solves step generation.

Claims (6)

A substrate made of a transparent insulating material, a gate electrode formed of metal on the substrate, a first insulating film formed on the gate electrode, a semiconductor film formed on the first insulating film, and the semiconductor at a position corresponding to the gate electrode. A source / drain electrode formed on the semiconductor film, a passivation film formed on the source / drain electrode, an SOG film formed on the passivation film, and eliminating a step, and formed on the SOG film so as to expose the film. A thin film transistor substrate of a liquid crystal cell comprising a pixel electrode connected to an electrode. The thin film transistor substrate of claim 1, further comprising a gate oxide layer formed on the gate electrode. The thin film transistor substrate of claim 1, further comprising an exogenous semiconductor film formed on the semiconductor film to expose the semiconductor film at a position corresponding to the gate electrode. A substrate made of a transparent insulating material, a gate electrode formed of metal on the substrate, a first insulating film formed on the gate electrode, a semiconductor film formed on the first insulating film, and corresponding to the gate electrode on the semiconductor film Eliminates the step formed on the source / drain electrode, which is a metal layer formed on the semiconductor film so that the etch stopper insulating film formed on the portion, the etch stopper insulating film on the portion corresponding to the gate electrode, is exposed. A thin film transistor substrate of a liquid crystal cell, comprising: an SOG film and a pixel electrode formed on the SOG film and connected to the source / drain electrodes. The thin film transistor substrate of claim 4, further comprising a gate oxide layer formed by oxidizing the gate electrode formed on the gate electrode. 6. The thin film transistor substrate of claim 5, further comprising an exogenous semiconductor film covering a portion on the etch stopper insulating film and being exposed to expose the etch stopper insulating film in a portion corresponding to the gate electrode.