KR100379366B1 - Method for fabricating liquid crystal display - Google Patents

Abstract

PURPOSE: A method for fabricating a liquid crystal display is provided to prevent a semiconductor layer from being exposed to plasma when a capacitor of the liquid crystal display is formed to remove a damage in the semiconductor layer. CONSTITUTION: A semiconductor layer is formed on an insulating substrate(11). A gate insulating layer is formed on the semiconductor layer. The first gate electrode is formed on the gate insulating layer. The first and second impurity regions(12a,12b) are provided in the semiconductor layer using the first gate electrode as a mask. The second gate electrode and a capacitor upper electrode are respectively formed on the first gate electrode and gate insulating layer. An interlevel insulating layer(17) having the first and second contact holes exposing the first and second impurity regions are formed on the overall surface of the substrate. Source and drain electrodes(20,21) are formed on the interlevel insulating layer to be electrically connected to the first and second impurity regions through the first and second contact holes.

Description

Manufacturing method of liquid crystal display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a liquid crystal display device capable of stabilizing device characteristics by eliminating damage to a semiconductor layer during capacitor manufacturing of a liquid crystal display device.

A method of manufacturing a conventional liquid crystal display device will be described below with reference to FIGS. 1A to 1G.

1A to 1F are sectional views of the manufacturing process of a conventional liquid crystal display device.

According to the drawing, in the conventional method of manufacturing a liquid crystal display device, as shown in FIG. 1A, a transparent insulating substrate 1 is prepared, and amorphous silicon is deposited on the transparent insulating substrate 1 by LPCVD. Next, the semiconductor layer 2 is formed by patterning it into a predetermined pattern.

Subsequently, as shown in FIG. 1B, a photoresist film 3 is applied to a predetermined portion of the semiconductor layer 2, and then P ⁺ or B ⁺ is primarily formed using the photoresist film 3 as a mask. By implanting ions into the surface, the lower electrode 2a of the capacitor is formed in the semiconductor layer 2. Then, the photoresist film 3 remaining on the semiconductor layer 2 is etched by plasma etching.

At this time, the portion of the semiconductor layer 2 covered with the photoresist film 3 is damaged as the photoresist film 3 is etched, as shown in FIG. 1C, while the surface thereof is exposed to the plasma state.

Subsequently, as shown in FIG. 1D, the gate insulating film 4 is formed on the semiconductor layer 2 by a dry thermal oxidation process.

Then, as shown in FIG. 1E, a doped polysilicon layer and a tungsten silicide layer were successively deposited on the front surface of the substrate by LPCVD and sputtering, respectively, and then patterned into a mask for a common storage line of the gate line and the capacitor. Thus, the gate electrodes 5 and 5a and the upper electrodes 6 and 6a of the capacitor are formed.

In this way, the capacitor manufacturing of the liquid crystal display device is completed.

Subsequently, P ⁺ or B ⁺ is ion-implanted into the entire surface of the substrate with the gate electrodes 5 and 5a as masks, so that the so-called region 2b and the drain region 2c are formed in the surface of the semiconductor layer 2. Form.

In this case, the train region 2c is formed to be electrically connected to the lower electrode region 2b of the capacitor.

Subsequently, as shown in FIG. 1F, SiO ₂ is deposited on the entire surface of the substrate by CVD to form an interlayer insulating film 7.

Then, predetermined portions of the interlayer insulating layer 7 are etched by dry etching so that the source region 2b and the drain region 2c are exposed.

Subsequently, as shown in FIG. 1G, by depositing A1 on the interlayer insulating film 7 and then patterning it in a predetermined pattern to form the source / drain electrodes 8 and 9, transistors and capacitors of the liquid crystal display device. Complete the manufacture of

The conventional liquid crystal display device uses a plasma etching method to remove the photoresist film 3 after the ion implantation process for forming the storage capacitor electrode, as shown in FIG. 1B, wherein the photoresist film 3 is removed. Since the semiconductor layer 2 is exposed to the plasma state, the portion of the semiconductor layer 2 which is the active layer region of the transistor is damaged as in the "A" portion of FIG. 1C.

Therefore, since the portion of the semiconductor layer 2 which is the active layer region is damaged, the electrical characteristics of the seed TFT are degraded.

In addition, since a predetermined portion of the surface of the semiconductor layer 2 is etched at the time of removing the photoresist film, the film thickness cannot be precisely adjusted, and thus the production yield is low.

On the other hand, since the lower electrode of the capacitor is conventionally formed by using a photoresist mask, a process of applying and removing the photoresist film is added, thereby increasing the manufacturing process time.

On the other hand, the conventional manufacturing method of the liquid crystal display device is cumbersome to perform two ion implantation process.

In addition, the conventional manufacturing method of the liquid crystal display device has a problem in that the thickness of the semiconductor layer cannot be accurately adjusted because the surface of the semiconductor layer is etched when the photosensitive film is removed.

Accordingly, an object of the present invention is to provide a method of manufacturing a liquid crystal display device capable of stabilizing device characteristics by eliminating damage to a semiconductor layer during capacitor manufacturing.

In addition, another object of the present invention is to provide a method of manufacturing a liquid crystal display device which can reduce the number of manufacturing process to shorten the process time.

The present invention for achieving the above object comprises the steps of preparing an insulating substrate; Forming a semiconductor layer on the insulating substrate; Forming a gate insulating film on the semiconductor layer; Forming a first gate electrode on the gate insulating film; Forming first and second impurity regions in the semiconductor layer using the first gate electrode as a mask; Forming an upper electrode of a second gate electrode and a capacitor on the first gate electrode and the semiconductor layer, respectively; Forming a protective film on a front surface of the substrate having first and second contact holes exposing the first and second impurity regions; And forming a source / drain electrode on the passivation layer so as to be electrically connected to the first and second impurity regions through the first and second contact holes.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2A to 2G are sectional views of the manufacturing process of the liquid crystal display device according to the present invention.

According to the drawing, as shown in FIG. 2A, a transparent insulating substrate 11 is prepared, amorphous silicon is deposited on the insulating substrate 11 by LPCVD, and then patterned into a predetermined pattern to form a semiconductor layer ( 12) form.

Subsequently, as shown in FIG. 2B, the gate insulating film 13 is formed on the entire surface of the substrate by a dry thermal oxidation process.

Then, as shown in FIG. 2C, polysilicon doped on the entire surface of the substrate is deposited by LPCVD, and then patterned with a mask for a gate line to form the first gate electrode 14.

Subsequently, as shown in FIG. 2D, the first impurity region 12a and the first impurity region 12a in the semiconductor layer 12 are implanted by ion implantation of B ⁺ or P ⁺ on the entire surface of the substrate using the first gate electrode 14 as a mask. 2 impurity regions 12b are formed.

In this case, the first impurity region 12a is used as a source region of the transistor, and the second impurity region 12b is used as a drain region of the transistor and a lower electrode of the capacitor.

Next, as shown in FIG. 2E, a tungsten silicide film WSiχ is deposited on the front surface of the substrate by a sputtering method, and then, the tungsten silicide film WSiχ is deposited in a predetermined pattern so that only the upper portion of the first gate electrode 14 and the upper portion of the gate insulating film 13 remain. By patterning, the second gate electrode 15 and the upper electrode 16 of the capacitor are formed.

In this case, the second gate electrode 15 is formed smaller than the width of the first gate electrode 14 in consideration of misalignment on the first gate electrode 14.

Subsequently, as shown in FIG. 2F, SiO ₂ is deposited on the entire surface of the substrate by CVD to form an interlayer insulating film 17.

Next, the interlayer insulating layer 17 and the gate insulating layer 13 are etched to expose the first and second impurity regions 12a and 12b to form first and second contact holes 18 and 19.

As shown in FIG. 2G, the interlayer insulating layer may be electrically connected to the first and second impurity regions 12a and 12b through the first and second contact holes 18 and 19. The Al is deposited on the substrate 17 by a sputtering method and then patterned into a predetermined pattern to form the source / drain electrodes 20 and 21 to complete transistors and capacitors of the liquid crystal display.

As described above, the liquid crystal display according to the present invention does not have to be damaged since the semiconductor layer is not exposed to the plasma state because the photosensitive film does not have to be removed using the plasma etching method as in the related art.

Therefore, since the semiconductor layer is not subjected to plasma damage, the electrical characteristics of the transistor are stabilized, and the film thickness is precisely controlled.

In addition, in the ion implantation process for forming the source / drain region of the transistor and the lower electrode region of the capacitor, the liquid crystal display device according to the present invention is different from the conventional ion implantation process. Regions may be formed.

In the present invention, during the ion implantation process, a separate photoresist film is applied as in the prior art, and the process of eliminating the photoresist film after ion implantation using the photoresist film as a mask is not necessary, thereby reducing the number of manufacturing steps. It is shortened.

1A to 1G are sectional views of the manufacturing process of a conventional liquid crystal display device.

2A to 2G are sectional views of the manufacturing process of the liquid crystal display device according to the present invention.

* Description of the symbols for the main parts of the drawings *

11 insulation board 12 semiconductor layer

12a: first impurity region 12b: second impurity region

13 gate insulating film 14 first gate electrode

15: second gate electrode 16: upper electrode (capacitor)

17 interlayer insulating film 18 first contact hole

19: second contact hole 20, 21: source / drain electrode

Claims (7)

Preparing an insulating substrate; Forming a semiconductor layer on the insulating substrate; Forming a gate insulating film on the semiconductor layer; Forming a first gate electrode on the gate insulating film; Forming first and second impurity regions in the semiconductor layer using the first gate electrode as a mask; Forming a second gate electrode and an upper electrode of a capacitor on the first gate electrode and the gate insulating film, respectively; Forming an interlayer insulating film having first and second contact holes exposing the first and second impurity regions on a front surface of the substrate; And forming a source / drain electrode on the interlayer insulating layer so as to be electrically connected to the first and second impurity regions through the first and second contact holes. The method of claim 1, The first gate electrode is formed of doped polysilicon. The method of claim 1, And the first impurity region forms a source region of a transistor. The method of claim 1, And the second impurity region forms a drain region of a transistor and a lower electrode of a capacitor. The method of claim 4, wherein The drain region of the transistor and the lower electrode of the capacitor are formed by one ion implantation process. The method of claim 1, And the upper electrode of the second gate electrode and the capacitor is formed of a tungsten silicide layer. The method of claim 1, The width of the second gate electrode is smaller than the width of the first gate electrode manufacturing method of the liquid crystal display device.