KR20020039466A - Method for manufacturing liquid crystal display device - Google Patents

Abstract

PURPOSE: A method of fabricating a liquid crystal display is provided to secure electrical contact between gate and data electrodes and a transparent pixel electrode. CONSTITUTION: A gate metal such as Al is deposited on a glass substrate to form a gate electrode(10), and a gate insulating layer(12) and an active layer are formed on the substrate including the gate electrode. A data electrode(18) is formed on the gate insulating layer, a protection layer(20) is formed on the substrate, and a contact hole is formed on a portion corresponding to the gate electrode and the data electrode. A Mo thin film is formed on the overall surface of the substrate including the contact hole. An ITO pixel electrode(26) is formed on the Mo thin film.

Description

Manufacturing method of liquid crystal display device {METHOD FOR MANUFACTURING LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display, and more particularly, to forming a gate and a data electrode in the process of forming a TFT-array of a TFT-LCD, and transparent of the gate / data electrode and an indium tin oxide (ITO). The present invention relates to a method of manufacturing a liquid crystal display device for ensuring electrical connection between pixel electrodes.

Compared to the CRT (Cathod Ray Tube) display device that reproduces color images by hitting the color ratio generated from the R / G / B electron gun against the R / G / B pixels formed on the fluorescent panel, LCD devices designed to be lightweight and thin have been applied to various electronic products (for example, wall-mounted televisions).

The LCD device comprises a first substrate on which a TFT array is formed, a second substrate on which a color filter composed of R / G / B pixels is formed, and a liquid crystal cell injected between the first substrate and the second substrate, When the arrangement direction of the liquid crystal cell is changed by applying a graphic data signal to the TFT array of the first substrate, the light transmitted through the liquid crystal cell passes through the color filter and generates a specific color to reproduce the color image. .

In the TFT-LCD device, an aluminum (Al) -alloy is generally applied to the unit TFT element as a large electrode / definable electrode material for the gate electrode and the data electrode (source / drain electrode), and the pixel electrode is disposed on the uppermost layer. ITO as is laminated and patterned.

For this reason, a buffer layer made of Mo is used to prevent an increase in contact resistance between Al-alloy and ITO. According to the application example of the buffer layer, in the case of FIG. 1A, the upper and lower portions of the Al alloy layer 1 are used. Buffer layers 2a and 2b are formed by Mo, and in the case of FIG. 1B, the buffer layer 2 is formed only on the Al alloy layer 1. In the case of FIG. 1C, the outer periphery of the Al alloy layer 1 is formed. Accordingly, the buffer layer 2 is formed.

Here, the buffer layers 2a, 2b; 2 generally deposit Mo layers in the range of several hundreds to several thousand kilos, and contact holes for contacting the electrode by the Al alloy layer 1 and the transparent electrode ITO. Even when etching etc., it forms so that the Mo layer may remain | survives enough.

By the way, when the buffer layer (2a, 2b; 2) described above is involved, it is advantageous in that the contact resistance with ITO is kept below a certain level for pure Al or Al-alloy, but for forming the buffer layer Not only is the deposition process complicated, there is a disadvantage that the process time and the cost are increased, and the thickness of the electrode is increased, thereby reducing the reliability of the device.

Accordingly, the present invention has been made in view of the above-described prior art, and a thin Mo layer is formed on a contact portion with a transparent electrode such as ITO of an electrode formed from a single layer of an Al-alloy layer to form an Al-alloy layer and a Mo layer. It is an object of the present invention to provide a method for manufacturing a liquid crystal display device which is made to react to prevent an increase in contact resistance with a transparent electrode.

In order to achieve the above object, according to a preferred embodiment of the present invention, a process of forming a gate electrode by stacking an Al-based gate metal on a glass substrate and patterning a gate insulating film and an active layer on the gate electrode, Forming a protective layer on the film, forming a protective layer, forming a contact hole at a position corresponding to the gate electrode and the data electrode, laminating a Mo thin film layer on the entire surface including the contact hole, and Provided is a method of manufacturing a liquid crystal display device comprising patterning and forming ITO in contact with the gate electrode and the data electrode in such a manner that an increase in contact resistance is prevented by the Mo thin layer.

According to an embodiment of the present invention, the Mo thin film layer has a Mo deposition temperature or a heat treatment temperature condition so that the Mo thin film layer remains only in the contact hole formed in the gate electrode and the data electrode to form Mo and Al-alloy bonding layer. Then, the entire surface etching process is performed, and ITO in contact with the remaining Mo thin layer is patterned.

On the other hand, in another embodiment of the present invention, the liquid crystal display device is manufactured in a structure in which the ITO is laminated on the entire surface of the Mo thin film layer.

According to the manufacturing method of the liquid crystal display device according to the present invention, a Mo thin film layer is formed by forming a gate electrode and a data electrode as a single layer of Al-alloy, and then Mo as Al-alloy and buffer layer of the gate electrode and data electrode. The reaction is prevented from increasing the buckle resistance with the transparent electrode ITO.

1A to 1C are views for explaining a structure of an electrode formed according to a conventional method for manufacturing a liquid crystal display device;

FIG. 2 is a table for explaining contact resistance during excessive etching of Mo and Al-alloy samples forming a stacked structure of a gate electrode and a data electrode of a liquid crystal display;

FIG. 3 is a graph illustrating an analysis result of overetching of Mo and Al-alloy samples forming a stacked structure of a gate electrode and a data electrode of a liquid crystal display;

FIG. 4 is a table showing resistance change due to heat treatment of Mo and Al-alloy samples forming a stacked structure of a gate electrode and a data electrode of a liquid crystal display;

5 is a graph illustrating thermal analysis results of an Mo / Al-alloy / Mo structure forming a stacked structure of a gate electrode and a data electrode of a liquid crystal display device;

6A to 6I are flowcharts illustrating a method of manufacturing a liquid crystal display device according to an exemplary embodiment of the present invention;

7A to 7C are flowcharts illustrating a manufacturing method of a liquid crystal display according to another exemplary embodiment of the present invention.

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

10: gate electrode, 12: gate insulating layer,

18: data electrode, 20: protective layer,

22: contact hole, 24: Mo thin layer,

26: ITO.

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

First, the technical principle of the present invention will be described based on the electrode structure shown in FIGS. 1A to 1C. In the case where the Mo buffer layer is over-etched, as shown in Table 1 shown in FIG. 2, the 300-μM upper-Mo buffer layer is deposited, and the etching is performed even if the over-etching is performed to over 1200 to the level of 1200 by dry etching. The contact resistance with the ITO deposited later does not increase as compared with the normal conditions (ie, the condition in which Mo remains). However, when the upper-Mo buffer layer does not exist from the beginning, the contact resistance increases considerably after the heat treatment and is not practically used. It will not be possible.

In addition, when the composition distribution of the sample over-etched in FIG. 2 is examined, the result shown in FIG. 3 is obtained. Thus, even in the case of over-etching, a small amount of Mo remains. In this case, the sample used was subjected to the deposition of the gate insulating layer at 350 ° C. or higher after the formation of the gate electrode (Mo-Al-Mo in the form shown in FIG. 1A), and in the process, between the Mo and Al alloys. It is believed that an interfacial reaction occurs. The interfacial reaction of the Mo-Al alloy layer thus formed seems to remain without etching with Mo dry etching gas (SF6, etc.) (Al dry dry etching gas: BCl3 + Cl2, etc.). The reaction layer prevents an increase in contact resistance between Al alloy and ITO.

Next, considering the resistance change due to the heat treatment (350 ° C.) of the Mo / Al-alloy layer / Mo structure and the Al (-alloy) structure, as shown in FIG. 4, when the Mo buffer layer is present, 350 ° C. heat treatment is performed. In this case, the resistance is increased, and when the buffer layer is not present, it can be seen that there is no increase in the resistance even if heat treatment is performed at 350 ° C. That is, when the Mo buffer layer is present it can be seen that there is any reaction between the Al-alloy layer and the Mo buffer layer at a temperature of 350 ℃ or more.

And, considering the thermal analysis results of the Mo / Al (-alloy layer) / Mo structure, it can be seen that the reaction of Al (-alloy) and Mo is formed from around 350 ℃ in the thermal analysis results shown in FIG.

Therefore, in the present invention, a thin Mo layer is formed only at a contact portion with a transparent pixel electrode such as ITO of an electrode formed of a single layer of Al-alloy based on the above-described results to react the Al-alloy with Mo to form a transparent electrode. This prevents an increase in contact resistance.

6A to 6I are flowcharts illustrating a method of manufacturing a liquid crystal display device according to an exemplary embodiment of the present invention.

According to the present invention, the gate electrode 10 is formed on the glass substrate in FIG. 6A, and the gate electrode 10 is formed of an Al-alloy single layer.

After the gate electrode 10 is formed, the gate insulating layer 12, the a-Si layer 14, and the n + a-Si layer 16 are formed on the entire surface including the gate electrode 10 in FIG. 6B. The layers are sequentially stacked and then patterned into a predetermined shape (Fig. 6C).

In FIG. 6D, the Al-alloy single layer is stacked to form the data electrode 18 on the structure including the gate insulating layer 12, and then etching is performed using, for example, an S / D mask. The protective layer 20 is formed in the structure in which the electrode 18 was formed (FIG. 6E).

After the protective layer 20 is formed, a contact hole 22 is formed at a position corresponding to the gate electrode 10 and the data electrode 18 (FIG. 6F). The gate metal for the formation of Al-alloy monolayer is involved in the procedure of the 5-mask process.

After the contact hole 22 is formed, the entire surface of the Mo thin film layer 24 is deposited at a high temperature process of 300 ° C. or higher, or when it is deposited at a lower temperature, the film is heat-treated at 300 ° C. or higher following the deposition (FIG. 6G). ). Here, the thickness of the Mo thin film layer 24 is advantageous to be set as thin as possible in consideration of the process time, it should be noted that during the deposition temperature of the substrate should be maintained at a high temperature of about 350 ℃ or more, which is This is to ensure the reaction of Mo and Al-alloy on the contact hole 22 surface. When the entire surface of Mo is deposited by the process, Mo reacts with Al-alloy in the interface with Al-alloy. do.

Then, the entire surface etching process is performed on the Mo thin film layer 24. The etching is performed by dry etching using a gas (SF6 or the like) capable of etching Mo, and the etching degree thereof is a protective layer ( While 20 is set to a level that does not cause serious damage, all Mo layers on the protective layer 20 are set to a level which is higher than that of etching removal. In this case, the layer on which the Al-alloy and Mo react on the surface of the contact hole 22 is not etched away and the Mo component remains.

That is, a bonding layer structure of Mo and Al-alloy is formed at the position of the contact hole 22 (FIG. 6H), and the ITO contact is made between the gate electrode 12 and the data electrode 18. The ITO is stacked so that ITO contact is made between the data electrode 18 and the transparent pixel electrode (FIG. 6I).

Therefore, according to an embodiment of the present invention, the Mo thin film layer is formed only at the contact portion with the transparent electrode such as ITO of the electrode formed of a single layer of Al-alloy, thereby reacting the Al-alloy with Mo to form a transparent electrode. An increase in contact resistance is prevented.

7A to 7C illustrate a method of manufacturing a liquid crystal display according to another exemplary embodiment of the present invention. The present exemplary embodiment provides a more simplified process structure than the aforementioned exemplary embodiment.

That is, FIG. 7A is a process corresponding to FIG. 6F and the gate electrode 10 and the data electrode 18 are formed after the protective layer 20 is formed in a state in which the process corresponding to FIGS. 6A to 6E is performed. The contact hole 22 is formed at a position corresponding to), and in FIG. 7B corresponding to FIG. 6G, after several tens of Mo thin film layers 24 are formed in the overall structure, an ITO 26 is formed thereon. By the simultaneous patterning of the Mo thin film layer 24 and the ITO 26, the structure of FIG. 7C corresponding to FIG. 6H is obtained.

Here, the thickness of the Mo thin film layer 24 is limited to a thickness (~ several tens of microseconds) or less sufficient to transmit visible light, which is because the Mo thin film layer 24 is disposed below the ITO 26. This is to ensure the transmittance of.

Therefore, since Mo remains between the transparent electrode and the Al-alloy in the structure shown in FIG. 7C, the contact therebetween is ensured.

On the other hand, the present invention is not limited to the above examples and various changes and modifications can be made within the scope not departing from the technical gist and gist of the invention.

As described above, according to the manufacturing method of the liquid crystal display device according to the present invention, the Mo thin film layer is formed only on the contact portion of the gate electrode (data electrode) formed of a single layer of Al-alloy with the transparent electrode such as ITO. The increase in contact resistance with the transparent electrode can be prevented by the reaction of Al-alloy with Mo without employing the structure.

In addition, in the present invention, as the overall vertical size of the device is reduced as the multi-layer structure is not adopted for the gate electrode / data electrode, the process steps can be reduced, so that the operation of the equipment is easier, and the production yield and product yield and The reliability can be improved.

Claims (6)

Stacking an Al-based gate metal on a glass substrate to form a gate electrode, and patterning a gate insulating film and an active layer on the upper side thereof; Forming a protective layer after forming a data electrode on the gate insulating layer and forming a contact hole at a position corresponding to the gate electrode and the data electrode, Stacking the Mo thin film layer on the entire surface including the contact hole; And patterning the ITO in contact with the gate electrode and the data electrode in such a way that an increase in contact resistance is prevented by the Mo thin film layer. The method of claim 1, wherein the Mo thin film layer has a temperature condition such that the Mo thin film layer remains only at the contact hole formed in the gate electrode and the data electrode to form an Al-alloy bonding layer. And ITO in contact with the remaining Mo thin film layer is patterned. The liquid crystal display device according to claim 1 or 2, wherein the Mo thin film layer is laminated in a state in which the glass substrate is maintained at about 300 ° C or higher, or deposited at a lower temperature, and subjected to a heat treatment process of 300 ° C or higher. Manufacturing method. The method according to claim 1, wherein the ITO is laminated on the entire surface of the Mo thin film layer. The method according to claim 4, wherein the Mo thin layer is deposited at 300 ° C. or higher or at a lower temperature and undergoes a heat treatment of 300 ° C. or higher, and the Mo thin layer is formed to a thickness of several tens of micrometers or less for transmitting visible light. Method of manufacturing a liquid crystal display device. The method of claim 4, wherein the Mo thin film layer and the ITO are patterned at the same time.