JPH0792488A - Production of liquid crystal display substrate - Google Patents

Abstract

PURPOSE:To decrease the number of production processes by anodially oxidizing the surface of metallic layers constituting either of gate bus lines and signal bus lines and etching the metallic layers constituting pixel electrodes. CONSTITUTION:A transparent conductive layer 11 and the metallic layer 12 are successively formed over the entire area on the main surface of a glass substrate 1 and are respectively selectively etched by using the same mask, by which the gate bus lines 2 and the pixel electrodes 4 are formed. A mask is so formed as to cover the surface on the pixel electrode 4 side and oxidized films 13 are formed by using an anodic oxidation method on the surfaces (including the flanks) of only the metallic layers 12 constituting the gate bus lines 2 exposed from this mask and thereafter, the mask is removed. The entire part of the metallic layers 12 constituting the pixel electrodes 4 is etched by using an etching liquid for the metallic layers 12. The need for using the mask in etching of the metallic layers 12 is, therefore, entirely eliminated at this time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display substrate, for example, a method of manufacturing an active matrix type liquid crystal display substrate using thin film transistors and the like.

[0002]

2. Description of the Related Art A liquid crystal display substrate of an active matrix type has a nonlinear element (switching element) corresponding to each of a plurality of pixel electrodes arranged in a matrix.
Is provided. Since the liquid crystal in each pixel is theoretically always driven (duty ratio 1.0), the active system has better contrast than the so-called simple matrix system, which employs the time-division driving system. It is becoming an indispensable technology for display boards. A typical example of the switching element is a thin film transistor (TFT).

An active matrix type liquid crystal display device using a thin film transistor is disclosed in, for example, Japanese Patent Laid-Open No. 63-309921 and "1.
2.5-inch active matrix color LCD ", Nikkei Electronics, pages 193-210, 1986 12
Known on the 15th of March, published by Nikkei McGraw-Hill, Inc.

[0004]

However, in such a liquid crystal display substrate, since the number of manufacturing steps is extremely large, there is a strong demand for reduction of the number of steps.

Therefore, the applicant has already proposed a method of forming the signal bus line and the pixel electrode in the same pattern, a method of forming the gate bus line and the pixel electrode in the same pattern, and the like. There is a demand for further reduction in man-hours.

For example, when the signal bus line and the pixel electrode are formed in the same pattern, the pixel electrode needs to be formed of a transparent conductive layer. Therefore, the signal bus line is similarly formed of a transparent conductive layer. Will end up. Since the transparent conductive layer generally has a high resistance, there is also a problem that the high resistance at the time of writing a signal causes an adverse effect. Such an adverse effect also occurs when the gate bus line and the pixel electrode are formed in the same pattern.

Therefore, the present invention has been made under such circumstances, and an object of the present invention is to provide a method of manufacturing a liquid crystal display substrate in which the number of manufacturing steps is reduced.

Another object of the present invention is to provide a method of manufacturing a liquid crystal display substrate which can obtain a gate bus line or a signal bus line having a low resistance.

[0009]

In order to achieve such an object, the present invention basically provides a liquid crystal side surface of one of the glass substrates opposed to each other with a liquid crystal interposed therebetween. A liquid crystal display in which a gate bus line, a signal bus line, and a pixel electrode are formed on one side, and one of the gate bus line and the signal bus line and the pixel electrode are formed from a laminated body of a transparent conductive layer and a metal layer. A method of manufacturing a substrate, comprising: a step of anodizing a surface of a metal layer forming one of the gate bus line and the signal bus line; and a step of etching a metal layer forming a pixel electrode. It is a thing.

[0010]

According to the method of manufacturing a liquid crystal display substrate having such a structure, the surface of the metal layer of the gate bus line or the signal bus line formed of a laminated body of the transparent conductive layer and the metal layer is anodized by anodic oxidation. By covering with, it becomes possible to completely remove the unnecessary metal layer on the pixel electrode side without etching the metal layer.

In this case, a mask is not required for etching the metal layer on the pixel electrode side, so that the number of manufacturing steps can be reduced.

Further, the gate bus line or the signal bus line has a transparent conductive layer as an underlying layer, but since it has a laminated structure including a metal layer as an upper layer, it has a high resistance. It also has the effect of being able to prevent

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Each embodiment of the method for manufacturing a liquid crystal display substrate according to the present invention will be described below with reference to the drawings.

[Embodiment 1] First, the structure of a liquid crystal display substrate to which this embodiment is applied will be described with reference to FIG.
FIG. 2 shows a configuration of one of a plurality of matrix electrodes formed in a matrix and its periphery.

In the figure, on the main surface of the glass substrate 1,
There is a gate bus line 2 extending in the x direction in the figure, and a plurality of gate bus lines 2 are arranged in parallel in the y direction in the figure in parallel with each other.

On the other hand, there is a signal bus line 3 extending in the y direction in the figure, and a plurality of the signal bus lines 3 are arranged in parallel in the x direction in the figure. These signal bus lines 3 are insulated from each other by an interlayer insulating film formed at least with the gate bus lines 2.

A pixel electrode 4 is formed in a rectangular area surrounded by the gate bus line 2 and the signal bus line 3. The pixel electrode 4 is composed of a transparent conductive layer, and a part of the pixel electrode 4 extends to a portion of a thin film transistor (TFT) formed on the gate bus line 2 to form a source electrode 4A. .

The thin film transistor (TFT) is formed by sequentially forming the interlayer insulating film and the semiconductor layer, which will be a gate insulating film, on the surface of the gate bus line 2, and the source electrode on the semiconductor layer. The drain electrode 4B, which is formed so as to be opposed to 4A, is formed integrally with the signal bus line 3.

Further, the other part of the pixel electrode 4 extends to a part of the other gate bus line 2 and is overlapped with the interlayer insulating film interposed therebetween to form a capacitor in this overlap region. There is.

Such a structure is called a so-called inverted staggered structure because the gate bus line 2 serving as the gate electrode of the thin film transistor (TFT) is located below the semiconductor layer.

Next, a method of manufacturing the liquid crystal display substrate having the above structure will be described with reference to FIG. In this embodiment, the gate bus line and the pixel electrode are patterned at the same time. FIG. 1 is a sectional view taken along the line I-I of FIG.

Step 1. As shown in FIG. 1A, the transparent conductive layer 11 and the metal layer 12 are sequentially formed on the entire main surface of the glass substrate 1, and these are selectively etched by using the same photomask. 2 and the pixel electrode 4 are formed.

Step 2. As shown in FIG. 1B, a mask is formed so as to cover the surface on the pixel electrode 4 side, and the surface of only the metal layer 12 constituting the gate bus line 2 exposed from the mask (side surface) Oxide film 13 is formed by using an anodic oxidation method. Then, the mask is removed.

Step 3. As shown in FIG. 1C, the metal layer 12 forming the pixel electrode 4 is entirely etched with an etching solution for the metal layer 12. In this case, since the metal layer 12 forming the gate bus line 2 is covered with the oxide film 13 on its surface, it can be left without being etched.

Therefore, no mask is required for etching the metal layer 12 at this time.

Step 4. As shown in FIG. 1D, the insulating layer 14 is selectively covered with the gate bus line 2 sufficiently.
To form the gate bus line 2 on the surface of the insulating layer 14.
The semiconductor layer 15 is selectively formed thereon.

Then, a signal bus line 3 (not shown) is formed so as to be orthogonal to the gate bus line 2. At this time, at the same time as the formation of the signal bus line 3, the drain electrode 4B connected to the signal bus line 3 and laminated on a part of the surface of the semiconductor layer 15 and the transparent conductive layer 11 forming the pixel electrode 4 are formed. A source electrode 4A, which is connected and is laminated so as to face the drain electrode 4B, is formed on a part of the surface of the semiconductor layer 15.

After that, the protective film 16 is formed on the entire main surface of the glass substrate thus processed.

[Embodiment 2] This embodiment is an embodiment in which the signal bus lines and the pixel electrodes are simultaneously patterned by the inverted stagger structure shown in FIG. In FIG. 3, steps 1. As shown in FIG. 3A, first, the glass substrate 1
The gate bus line 2 is formed on the main surface of. In this case, it is composed of only a metal layer. Then, the insulating layer 14 is formed over the entire main surface of the glass substrate 1 so as to cover the gate bus line 2.

Gate bus line 2 on the main surface of insulating layer 14
The semiconductor layer 15 is selectively formed on the upper part.

Then, a signal bus line 3 (not shown) is formed so as to be orthogonal to the gate bus line 2. The signal bus line 3 is composed of a sequentially laminated body of a transparent conductive layer 11 and a metal layer 12.

At this time, at the same time when the signal bus line 3 is formed, the drain electrode 4B connected to the signal bus line 3 and stacked over a part of the surface of the semiconductor layer 15 and the drain electrode 4B facing the drain electrode 4B. Source electrode 4A to be laminated
Then, the pixel electrode 4 formed integrally with the source electrode 4A is formed.

Step 2. As shown in FIG. 3B, a mask is formed so as to cover the surface of the source electrode 4A and the pixel electrode 4 formed integrally with the source electrode 4A, and the drain electrode 4B exposed from the mask. Then, the oxide film 13 is formed on the surface (including the side surface) of the metal layer 12 forming the signal bus line 3 by using the anodic oxidation method. Then, the mask is removed.

Step 3. As shown in FIG. 3C, the metal layer 12 forming the source electrode 4A and the pixel electrode 4 is entirely etched by using an etching solution for the metal layer 12. In this case, since the metal layer 12 forming the drain electrode 4B and the signal bus line 3 is covered with the oxide film 13 on its surface, it can be left without being etched.

Therefore, no mask is required for etching the metal layer at this time.

Step 4. As shown in FIG. 3D, the protective film 16 is formed on the entire main surface of the glass substrate thus processed.
To form.

[Embodiment 3] The structure of a liquid crystal display substrate to which this embodiment is applied will be described with reference to FIG. Those having the same reference numerals as those in FIG. 2 have the same function. 2 is different from FIG. 2 in that the gate bus line 2 is positioned above the signal bus line 3 and such a structure is called a positive stagger structure.

Next, a method of manufacturing the liquid crystal display substrate having such a structure will be described with reference to FIG. In this embodiment, the gate bus line and the pixel electrode are patterned at the same time. FIG. 5 is a sectional view taken along line VV of FIG.

Step 1. As shown in FIG. 5A, signal bus lines 3 (not shown) are formed on the main surface of the glass substrate 1. At this time, the drain electrode 4A connected to the signal bus line 3 and the source electrode 4A separated from the signal bus line 3 are formed in the same step as the signal bus line 3.

Then, the semiconductor 15 is selectively formed at one end of the drain electrode 4B and one end of the source electrode 4B.

After that, the signal bus line 3 and the semiconductor layer 15
And one end of the source electrode 4A, and the source electrode 4A
The insulating layer 14 is formed so that the other end of the insulating layer 14 is exposed.

Further, the gate bus line 2 is formed on the main surface of the insulating layer 14 so as to be orthogonal to the signal bus line 3.
The gate bus line 2 includes one end of each of the drain electrode 4B and the source electrode 4A and the semiconductor layer 14 between them.
Positioned so as to be superposed on the transparent conductive layer 11
And a metal layer 12 are sequentially laminated.

At this time, the pixel electrode 4 connected to the other end of the source electrode 4A is also formed in the same step as the gate bus line 2.

Step 2. As shown in FIG. 5B, a mask is formed so as to cover the surface of the pixel electrode 4, and only the surface of the metal layer 12 (the side surface is exposed) which constitutes the gate bus line 2 exposed from the mask. Oxide film 13 is formed by using the anodic oxidation method. Then, the mask is removed.

Step 3. As shown in FIG. 5C, the entire metal layer 12 forming the pixel electrode 4 is etched using an etchant for the metal layer 12. In this case, since the metal layer 12 forming the gate bus line 2 is covered with the oxide film 13 on its surface, it can be left without being etched.

Therefore, no mask is required for etching the metal layer 12 at this time.

Step 4. As shown in FIG. 5D, the protective film 1 is formed on the entire main surface of the glass substrate 1 thus processed.
6 is formed.

According to the method of manufacturing a liquid crystal display substrate configured as in each of the above embodiments, the metal of the gate bus line 2 or the signal bus line 3 formed of a laminated body of the transparent conductive layer 11 and the metal layer 12 is used. By covering the surface of the layer 12 with an insulating film by anodic oxidation, the unnecessary metal layer 12 on the pixel electrode 4 side can be completely removed without etching the metal layer 12.

In this case, a mask is not required for etching the metal layer 12 on the pixel electrode 4 side, so that the number of manufacturing steps can be reduced.

The gate bus line 2 or the signal bus line 3 has the transparent conductive layer 11 in the lower layer thereof, but since it has the metal layer 12 in the upper layer, it has a high structure. It also has the effect of preventing resistance.

In this embodiment, the manufacturing method is shown on the premise of the pattern as shown in FIG. 2 or FIG. 3, but it goes without saying that the pattern is not necessarily limited to the above-mentioned pattern. Absent.

[0052]

As is apparent from the above description,
According to the method of manufacturing a liquid crystal display substrate of the present invention, it is possible to reduce the number of manufacturing steps.

[Brief description of drawings]

1A to 1D are process diagrams showing an embodiment of a method for manufacturing a liquid crystal display substrate according to the present invention.

FIG. 2 is a plan view showing an embodiment of a liquid crystal display substrate to which the manufacturing method according to the present invention is applied.

3A to 3D are process drawings showing another embodiment of the method for manufacturing a liquid crystal display substrate according to the present invention.

FIG. 4 is a plan view showing another embodiment of the liquid crystal display substrate to which the manufacturing method according to the present invention is applied.

5A to 5D are process diagrams showing another embodiment of the method for manufacturing a liquid crystal display substrate according to the present invention.

[Explanation of symbols]

 1 glass substrate 2 gate bus line 3 signal bus line 11 transparent conductive layer 12 metal layer 13 oxide film

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Haruo Matsumaru 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Electronic Device Division

Claims (1)

[Claims] 1. A gate bus line, a signal bus line, and a pixel electrode are formed on a liquid crystal side surface of one of the glass substrates arranged to face each other with a liquid crystal interposed therebetween. In a method of manufacturing a liquid crystal display substrate, in which one of the signal bus lines and the pixel electrode are formed from a laminated body of a transparent conductive layer and a metal layer, a metal layer forming one of the gate bus line and the signal bus line is formed. A method of manufacturing a liquid crystal display substrate, comprising: a step of anodizing and a step of etching a metal layer forming a pixel electrode.