JPH05341299A - Production of liquid crystal display panel - Google Patents

Abstract

PURPOSE:To provide the process for production which simplifies the process for forming the electrode wirings of a thin-film transistor matrix to be provided in an LCD to two-layered structures in which the front surface and flanks of low-resistance metals are coated with a metal for protection and the wire widths of the low-resistance metals in the electrode wirings widen. CONSTITUTION:This process for production is so constituted as to have a stage for forming two-layered films consisting of a first film 2 consisting of the low- resistance metal and a second film 3 consisting of the metal for protection thereon on an insulating substrate 1, a stage for patterning the two-layered films 4 by using a resist mask 5, a stage for depositing a third film 6 consisting of the respective metal for protection on the insulating substrate 1 on the outer side thereof and a stage for removing the third film 6 by anisotropic etching in such a manner that this film remains on the flanks of the two-layered films 4 and does not remain on the outer side thereof. The deposition thickness of the third film 6 is set larger than the thickness of the first film 2 at this time. The low-resistance metal is Al and Ti, Mo, W, Ni, Cr are usable for the metal for protection.

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 panel having a thin film transistor matrix as an active matrix driving system, and more particularly to electrode wiring of the thin film transistor matrix.

The above electrode wiring is used for a liquid crystal display panel (LC
In order to avoid signal delay due to the increase in size D), a low resistance is required, and a two-layer structure of a low resistance metal and a protective metal for protecting it is provided. It is desired to simplify and further reduce the resistance.

[0003]

2. Description of the Related Art The electrode wiring of a thin film transistor matrix in a liquid crystal display panel having a thin film transistor matrix is composed of aluminum, which is a low resistance metal for reducing the resistance, and a protective metal, such as titanium, which complements and protects its heat resistance and chemical resistance. The two-layer structure is such that titanium covers the exposed surface (top surface and side surface) of aluminum. This structure is required especially for electrode wiring on a transparent insulating substrate (glass substrate).

Conventionally, this electrode wiring is formed by the following steps. First, an aluminum film is formed on a glass substrate and patterned by photolithography. Then, a titanium film is formed thereon and patterned by photolithography to be wider than the aluminum pattern, thus completing the process.

The above photolithography requires the steps of coating a resist on an aluminum film or a titanium film, exposing and developing the resist film (forming a resist mask), and etching the aluminum film or the titanium film. Since a photomask for exposure must be prepared for each photolithography, many steps are required.

The pattern width of titanium is made wider than the pattern width of aluminum so that titanium covers the side surface of aluminum. The difference between the two pattern widths needs to be several μm or more in order to allow a positioning margin with respect to the aluminum pattern.

[0007]

Therefore, the conventional method of forming the above-mentioned electrode wiring has a problem that an extremely large number of steps are required because the photolithography is performed twice. When the number of processes increases, there is a problem that dust adheres.

Further, there is a problem that the line width of aluminum becomes smaller than the wiring width by several μm or more. If the thickness of the aluminum film is increased so as to compensate for the narrow line width of aluminum for lowering the resistance, there is a problem that the step coverage of the upper layer film is affected and the upper layer wiring is easily broken.

The present invention relates to an LCD having a thin film transistor matrix, and more particularly to an electrode wiring of the thin film transistor matrix, in which a process of forming a two-layer structure in which a top surface and a side surface of a low resistance metal are covered with a protective metal is simplified, and It is an object of the present invention to provide a method for manufacturing an LCD in which the line width of the low resistance metal is wide within the wiring width of the electrode wiring.

[0010]

In order to achieve the above object, a method of manufacturing an LCD according to the present invention provides an electrode wiring of the thin film transistor matrix in an LCD having a thin film transistor matrix formed on a transparent insulating substrate. Upon formation, a step of forming a two-layer film composed of a first film made of a low-resistance metal and a second film made of a protective metal thereover on the insulating substrate, and a step of patterning the two-layer film Depositing a third film of the protective metal on the patterned two-layer film and the insulating substrate outside the patterned two-layer film, and anisotropically etching the third film to a side surface of the two-layer film. And a step of removing it so as not to remain on the outside thereof.

In this case, it is desirable that the deposited thickness of the third film is equal to or larger than the thickness of the first film, the low resistance metal is aluminum, and the protective metal is
Be a metal selected from titanium, molybdenum, tantalum, tungsten, nickel, chromium.

[0012]

According to the steps described above, after the anisotropic etching is completed, desired electrode wirings are formed in which the upper surface and the side surface of the low resistance metal are covered with the protective metal. The second film covers the upper surface and the third film covers the side surfaces.

The photolithography required during that time is one time for patterning the above two-layer film, which is once less than the conventional two times. Instead, the third
Film deposition and anisotropic etching have been added, but the steps are much less than a single photolithography step. Therefore, the process is simplified as compared with the conventional case.

Of course, the patterning of the third film by the anisotropic etching corresponds to the conventional patterning of titanium (protective metal), but in a self-aligned manner with the pattern of the two-layer film. Since it is performed, it is virtually the same as without the alignment margin required conventionally,
The width of the low resistance metal is widened within the width of the electrode wiring to be formed.

The above conditions for the thickness of the third layer prevent the low resistance metal side surface from being exposed due to the thickness being too small during the anisotropic etching. In addition to the titanium, the above-mentioned various metals mentioned as the protective metal have characteristics for protecting the electrode wiring as well as titanium.

By the way, the anisotropic etching is performed in the third step.
In order to remove the second film from the side surface of the above-mentioned two-layer film so as not to remain outside thereof, the film thickness of the third film is slightly overetched. This slightly scrubs the surface of the second film in the two-layer film to remove surface residual impurities such as resist, so that the surface of the protective metal is cleaned. This cleaning is useful for preventing LCD defects.

[0017]

Embodiments of the present invention will be described below with reference to the side view showing the order of steps in FIG. This embodiment is an example in which aluminum and titanium are used for the gate electrode wiring by the sputtering method.

In FIG. 1, first, referring to (a), a first film 2 is formed on a glass substrate 1 which is a transparent insulating substrate.
As a low resistance metal, aluminum is deposited to a thickness of 500 Å, and as the second film 3, titanium serving as a protective metal is deposited to a thickness of 1000 Å to form a two-layer film 4. The deposition of aluminum to form the first film 2 and the deposition of titanium to form the second film 3 are performed using a DC sputtering apparatus in an Ar atmosphere at a pressure of about 0.005 Torr.
After that, a resist mask 5 having a pattern according to the electrode wiring to be formed (strictly, contracted inward from the contour by about 0.1 μm) is formed on the two-layer film 4.

Next, referring to (b), RIE (reactive ion etching) which is anisotropic etching.
Thus, using the resist mask 5 as a mask, the second film 3 and the first film 2 of the two-layer film 4 are etched into the same pattern. Then, the resist mask 5 is removed.

Next, referring to (c), the same protective metal (titanium) as that of the second film 3 is used as the third film 6 at 1000 Å.
Deposited to a thickness of. This deposition is performed under the same conditions as the deposition of the second film 3. The third film 6 covers the upper surface and the side surface of the two-layer film 4, and the surface on the glass substrate 1 is more than the surface on the two-layer film 4 by two.
The height of the layer film 4 is lowered by the step.

Next, referring to (d), the third film 6 is removed by RTE which is anisotropic etching so that the third film 6 is left on the side surface of the two-layer film 4 and not on the outer side thereof. For that purpose, the film thickness of the third film 6 is slightly overetched. As a result, the thickness of titanium, which is the second film 3 of the two-layer film 4, becomes about 800 Å, and at the same time, the titanium, which is the remaining third film 6, is the first film 2 of the two-layer film 4. By covering the side surface of aluminum with a thickness of about 800Å, and by covering the upper surface and side surface of aluminum, which is a low resistance metal, with titanium, which is a protective metal, electrode wiring with a clean surface is completed.

As is apparent from the above, the difference between the wiring width and the line width of the low resistance metal inside the electrode wiring is only about 0.16 μm, and the difference is several μm or more. Compared with the conventional method, the line width of the low resistance metal is widened and the resistance is reduced.

The protective metal used for the second film 3 and the third film 6 can be appropriately selected from titanium, molybdenum, tantalum, tungsten, nickel and chromium. In addition, the dimensions described in the embodiments are examples and LCDs
Can vary depending on the design of.

[0024]

As described above, according to the present invention, the present invention relates to an LCD having a thin film transistor matrix, and in particular to an electrode wiring of the thin film transistor matrix, it has a two-layer structure in which the upper surface and the side surface of a low resistance metal are covered with a protective metal. The manufacturing process is simplified, the line width of the low-resistance metal is widened within the wiring width of the electrode wiring, and further, the surface of the protective metal is cleaned. It greatly contributes to the improvement of performance.

[Brief description of drawings]

FIG. 1 is a side view of a process according to an embodiment.

[Explanation of symbols]

 1 Glass Substrate (Transparent Insulating Substrate) 2 First Film Made of Low Resistance Metal (Aluminum) 3 Second Film Made of Protective Metal (Titanium etc.) 4 Two Layer Film Composed of First Film and Second Film 5 Resist mask 6 Third film made of the same protective metal as the second film

Claims (3)

[Claims] 1. When forming an electrode wiring of the thin film transistor matrix in a liquid crystal display panel having a thin film transistor matrix formed on a transparent insulating substrate, a first film made of a low resistance metal is formed on the insulating substrate. A step of forming a two-layer film made of a second film of a protective metal thereon, a step of patterning the two-layer film, and a step of patterning the patterned two-layer film and the insulating substrate on the outside thereof. A step of depositing a third film made of a protective metal, and a step of removing the third film by anisotropic etching so as to leave the side surface of the two-layer film and not the outside thereof. A method of manufacturing a characteristic liquid crystal display panel. 2. The method for manufacturing a liquid crystal display panel according to claim 1, wherein the deposited thickness of the third film is equal to or larger than the thickness of the first film. 3. The low resistance metal is aluminum,
The method for manufacturing a liquid crystal display panel according to claim 1, wherein the protective metal is a metal selected from titanium, molybdenum, tantalum, tungsten, nickel, and chromium.