JPH1195239A - Production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obviate the generation of residues in an etching stage and to improve the corrosion resistance in post stages by using a sputtering method in which gas added with a prescribed amt. of gaseous steam is used in a deposition stage for transparent conductive films. SOLUTION: The sputtering method in which the gas added with the pressure divided gaseous steam at 0.002 to 0.010 Pa is used in the deposition stage of the transparent conductive films. When the partial pressures in the gaseous mixture are respectively specified to 0.001Pa, 0.002Pa and 0.05Pa and the X-ray diffraction spectra thereof are measured, the peak appearing at about 30 deg. of a 20 scale under 0.002Pa of the partial pressure of gaseous H2 O is lowered to about half that of the case the gaseous H2 O is not mixed or below the same. At the time of producing ITO as pixel electrodes in such a manner, the gaseous mixture composed of gaseous argon and the gaseous steam is used as a sputtering gas. As a result, the exertion of influence on an etching rate and the generation of microcrystals liable to produce the etching residues are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a method for manufacturing a transparent conductive film provided on an array substrate.

[0002]

2. Description of the Related Art At present, for example, thin-film transistors (TFs) are installed on display units of portable devices or notebook computers for reasons of high image quality, thinness, light weight and low power consumption.
Active matrix driven liquid crystal display devices in which a liquid crystal material is sealed between an active matrix substrate using a switching element such as T) and a counter substrate are widely used.

An active matrix substrate of the above-mentioned active matrix drive liquid crystal display device uses an ITO (indium oxide) film used as a pixel electrode. As a method of forming the ITO film, 200 °
There are known a method of performing sputtering at a high temperature of about C, and a method of forming a film at a low temperature, performing patterning, and then performing a heat treatment.

However, in the method of forming a film at a high temperature,
It is known that the etching rate in the etching step (post-process) for patterning is reduced, and the manufacturing efficiency is reduced.

In the method of forming a film at a low temperature, performing patterning, and then performing a heat treatment, it is known that an etching residue is generated in an etching step which is a later step, although the etching rate is high. For this reason, in a method of forming a film at a low temperature, a method of partial pressure (addition) of water vapor (H ₂ O) to a sputtering gas used for forming an ITO film has been proposed.

[0006]

However, in a conventional method of manufacturing an active matrix substrate, before forming a source electrode and a drain electrode, it is necessary to obtain good contact between each electrode and a low-resistance silicon film. The method includes a step of removing an oxide film layer on the surface of the low-resistance silicon layer by washing with a chemical solution containing hydrofluoric acid.
When a TO film is formed, there is an advantage that an etching residue does not occur in an amorphous film, but corrosion resistance is low, and even if an annealing process is performed after etching, there is a problem that the surface of the ITO film is corroded and becomes cloudy. .

An object of the present invention is to provide a method of manufacturing a liquid crystal display device having a transparent conductive film capable of improving the corrosion resistance in a subsequent step without generating a residue in an etching step.

[0008]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above-mentioned problems. An active matrix type liquid crystal display device provided with a transparent conductive film made of ITO on an insulating substrate is provided. The film formation step is characterized by a sputtering method to which steam gas is added, and the addition amount of the steam gas is 0.002 Pa to 0.010 Pa in partial pressure. .

Further, the present invention provides an active matrix type liquid crystal display device having a transparent conductive film made of ITO on an insulating substrate, wherein the step of forming the transparent conductive film comprises:
The sputtering method to which steam gas is added, and the amount of steam gas to be added is from 0.002 Pa to 0.010 Pa in partial pressure, and then has a heat treatment step by heat of 200 ° C. or more. It is characterized by.

[0010] Further, the present invention provides a method for manufacturing a semiconductor device, comprising:
In an active matrix type liquid crystal display device having a transparent conductive film consisting of, the step of forming the transparent conductive film is a sputtering method in which steam gas is added, and the amount of the steam gas added is a partial pressure. , 0.002Pa
To 0.010 Pa and then 200 ° C.
A heat treatment step using the heat described above, and thereafter, a surface treatment step using an aqueous solution containing hydrofluoric acid.

Still further, according to the present invention, the addition amount of the steam gas is 0.005 Pa to 0.010 Pa in partial pressure.
It is characterized by the following. Furthermore, according to the present invention, the addition amount of the steam gas is approximately 0.005 in partial pressure.
Pa, and the heat treatment temperature is preferably approximately 230 ° C.
It is characterized by being.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic cross section of an active matrix liquid crystal display panel used for an inverted stagger type liquid crystal display device.

As shown in FIG. 1, the liquid crystal display panel 1 comprises:
It comprises an active matrix substrate 10 having a thin film transistor (TFT) structure, a counter substrate 30 disposed opposite to the active matrix substrate 10, and a liquid crystal material 50 injected and sealed between the two substrates.

Next, a method of manufacturing a liquid crystal display panel will be described focusing on a manufacturing process of an active matrix substrate.
As shown in FIG. 1, first, a thin layer of a metal or an alloy is formed on one principal plane, that is, one surface of a glass substrate 11 to be used as an active matrix substrate 10 and etched into a predetermined pattern. Then, a scanning electrode (12) and a gate electrode 12 (not shown) are formed.

Next, a first gate insulating film 13 made of, for example, SiOx (silicon oxide) is laminated to a predetermined thickness by, for example, a plasma CVD method so as to cover the gate electrode 12.

Subsequently, a second gate insulating film 1 having a predetermined thickness
4 and a channel (semiconductor) in a TFT structure to be described later.
Amorphous silicon (hereinafter referred to as a-
A film 15 (shown as Si) and an etching stopper (protective insulating film) layer 16 are sequentially deposited.

Next, only the etching stopper layer 16 is etched and processed into a predetermined shape, for example, an island shape. Subsequently, a low-resistance silicon (hereinafter, referred to as Si) layer 17 is
A predetermined thickness is formed, and the low-resistance Si layer 17, the a-Si film 15, and the second gate insulating film 14 are etched in the same pattern.

Next, a transparent conductive film, that is, an ITO film 18, which is a pixel electrode, is formed by sputtering, for example, for 50 minutes.
A nanometer (hereinafter, referred to as nm) is formed. Note that I
As the TO film 18, indium oxide (In ₂ O ₃ )
To which 10% by weight (wt%) of tin (Sn) is added. The ITO film 18 was formed under the following conditions: a power density of 10 W / cm 2, an argon (Ar) gas as a sputtering gas, and a pressure of 0.6.
A mixed gas obtained by mixing Pa and water vapor (H ₂ O) gas at a partial pressure of 0.005 Pa is used. At this time, the temperature of the stage is normal temperature (room temperature).

Subsequently, a desired resist pattern is formed by using a photolithography technique, and wet etching is performed with an etching solution containing oxalic acid as a main component. Next, the photoresist is removed, and nitrogen (N
₂ ) Heat treatment in a gas atmosphere. The heating temperature is
230 ° C. The N ₂ gas atmosphere during heating is
It may be about 1 Torr.

Subsequently, a buffered hydrofluoric acid solution B-HF
A contact hole for applying a scanning signal to the scanning electrode (12) is formed in the first gate insulating film 13 by using.

Next, using a diluted hydrofluoric acid solution, a low-resistance Si
Removal of oxide film formed on the surface of layer 17 (annealing)
Then, a chromium (Cr) layer as an electrode member corresponding to the source electrode 19, the drain electrode 20, and a signal line (not shown) is deposited to a predetermined thickness, and patterned by disposing a photoresist. It goes without saying that the source electrode 19 is partially connected to the ITO film, that is, the pixel electrode 18.

Subsequently, using the source electrode 19 and the drain electrode 20 as a mask, the low-resistance Si layer 17
Is removed by etching. Hereinafter, the pixel electrode 18, the source electrode 19, the drain electrode 20, and the exposed etching stopper layer 16 are covered with a passivation film 21, and an alignment film 22 is further laminated.

Next, the opposing substrate 30 formed in a separate step from the above-mentioned active matrix substrate 10 is opposed to the active matrix substrate 10 at a predetermined interval, and a liquid crystal material 50 is injected between the two substrates and sealed. A liquid crystal display device is provided by adding a driving circuit or the like to a predetermined area. The opposite substrate 30 includes a glass substrate 31 and a well-known black matrix (light shielding film) 32 and a color filter 3.
3, in which the counter electrode 34 and the alignment film 35 are formed in this order, and various configurations have already been proposed, so detailed description will be omitted.

FIG. 2 is a graph showing the result of measuring an X-ray diffraction spectrum to evaluate the crystallinity of the pixel electrode, that is, the ITO film 18 in the liquid crystal display panel 1 shown in FIG.

As shown in FIG. 2, H ₂ in the mixed gas
When the X-ray diffraction spectrum was measured with the partial pressure of the O gas being 0.001 Pa, 0.002 Pa, and 0.005 Pa, respectively, the partial pressure of the H ₂ O gas was 0.002 Pa.
And the peak seen around 30 ° on the 2θ scale is H
It can be seen that the amount is reduced to about 1/2 as compared with the case where ₂ O gas is not mixed. Further, it is recognized that when the partial pressure of the H ₂ O gas is 0.005 Pa, the peak seen near 30 ° on the 2θ scale is greatly reduced.

FIG. 3 is a graph showing the relationship between the partial pressure of H ₂ O gas in the mixed gas and the transmittance. As shown in FIG. 3, the partial pressure of the H ₂ O gas in the mixed gas is 0.010 Pa
If it is higher than the above, the ITO film 18 is corroded by the step of removing the surface oxide film by HF, and the transmittance is rapidly lowered, and cloudiness below 80% which is a general specification of the transmittance of ITO is recognized. Was.

FIG. 4 is a graph showing the spectral transmittance of the pixel electrode in the liquid crystal display panel shown in FIG. 1, that is, the ITO film 18 manufactured by the above-described method. As shown in FIG. 4, visible light required in the liquid crystal display panel 1, that is, a wavelength of 400 to 700 nm.
It is recognized that a transmittance higher than 80% can be ensured in the entire region of the light.

[0028]

As described above, in the liquid crystal display device of the present invention, when producing ITO as a pixel electrode, an argon (Ar) gas is used as a sputtering gas at a pressure of 0.6.
A mixed gas obtained by mixing Pa and water vapor (H ₂ O) gas at a partial pressure of 0.005 Pa is used. Thus, it is possible to prevent the generation of fine crystal grains which are likely to become etching residues without affecting the etching rate in the next step. Therefore, it is possible to provide a liquid crystal display panel that has no etching residue and does not cause deterioration in image quality due to cloudiness or the like.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an active matrix substrate of a liquid crystal display device to which a manufacturing method according to an embodiment of the present invention is applied.

FIG. 2 is a graph showing a relationship between a partial pressure of water vapor gas in a mixed gas and an X-ray diffraction spectrum of the ITO film in the method of manufacturing an ITO film described with reference to FIG.

FIG. 3 is a graph showing the relationship between the partial pressure of water vapor gas in a mixed gas and the transmittance of the ITO film in the method of manufacturing an ITO film described with reference to FIG.

FIG. 4 is a graph showing the spectral transmittance of an ITO film obtained by the method of manufacturing an ITO film described with reference to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Active matrix type liquid crystal display panel, 10 ... Active matrix substrate, 11 ... Glass substrate, 12 ... Gate electrode, 13 ... First gate insulating film, 14 ... Second gate insulating film, 15 ... Amorphous silicon film, 16 ... Etching stopper layer, 17 ... Low resistance silicon layer, 18 ... Transparent conductive film, 19 ... Source electrode, 20 ... Drain electrode, 21 ... Passivation film, 22 ... Orientation film, 30 ... Counter substrate, 50 ... Liquid crystal material.

Claims (5)

[Claims] 1. An active matrix type liquid crystal display device having an ITO transparent conductive film on an insulating substrate, wherein the step of forming the transparent conductive film is performed by a sputtering method to which water vapor gas is added. A method for manufacturing a liquid crystal display device, wherein the amount of steam gas added is 0.002 Pa to 0.010 Pa in partial pressure. 2. An active matrix type liquid crystal display device having an ITO transparent conductive film on an insulating substrate, wherein the step of forming the transparent conductive film is performed by a sputtering method to which a water vapor gas is added. A method for manufacturing a liquid crystal display device, wherein the amount of steam gas to be added is 0.002 Pa to 0.010 Pa in partial pressure, and further comprises a heat treatment step using heat of 200 ° C. or more. 3. An active matrix type liquid crystal display device having an ITO transparent conductive film on an insulating substrate, wherein the step of forming the transparent conductive film is a sputtering method to which a steam gas is added. The added amount of gas is 0.002P
a to 0.010 Pa, and after that, a heat treatment step with heat of 200 ° C. or more,
And thereafter performing a surface treatment with an aqueous solution containing hydrofluoric acid. 4. The addition amount of the steam gas is set to a partial pressure.
4. The method for manufacturing a liquid crystal display device according to claim 1, wherein the pressure is 0.005 Pa or more. 5. The addition amount of said steam gas is set to a partial pressure.
The method according to any one of claims 1 to 3, wherein the heat treatment temperature is approximately 0.005 Pa, and the heat treatment temperature is preferably approximately 230 ° C.