JPH05313111A - Production of transparent conductive glass for liquid crystal display element - Google Patents

Abstract

PURPOSE:To efficiently produce a transparent conductive glass for the liq. crystal display element by using an in-line sputtering device. CONSTITUTION:A first coating chamber 2, a heating chamber 3 and a second coating chamber 4 are connected in this order to constitute an in-line sputtering device. A glass sheet is heated to <=200 deg.C in the first coating chamber 2 and coated with an alkali elution preventive film consisting of silicon dioxide, then the glass sheet is heated to >=300 deg.C in the heating chamber 3, densified and simultaneously heat-contracted, and the glass sheet is heated to >=300 deg.C in the second coating chamber 4 and coated with an ITO film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a liquid crystal display device having a glass substrate made of transparent conductive glass in which an alkali elution preventive film and a transparent conductive film are sequentially coated on a glass plate, particularly float glass having a soda lime silica composition. The present invention relates to a method for producing a transparent conductive glass that is preferably used.

[0002]

2. Description of the Related Art A transparent conductive glass for a liquid crystal display device of a simple matrix type is a float glass plate of soda lime silica composition coated with an alkali elution preventive film as an undercoat and ITO (tin-doped) as a transparent conductive film. A film coated with an (indium oxide) film is known. As the method for producing the transparent conductive glass, the washed glass plate is dipped in a fluorosilicic acid solution to form about 35
After coating an alkali elution preventive film consisting of a silicon dioxide film of ˜50 nm at room temperature (step 1 in FIG. 3) and then cleaning the glass again (step 2 in FIG. 3), vacuum deposition such as sputtering (FIG. 3). There is known a method of coating the ITO film by the step 3). Further, instead of the above silicofluoric acid solution, the glass plate is dipped in a diluting solution of an organosilicon compound such as polysiloxane, and then the glass plate is heated in air to decompose and remove the organic component to a thickness of 100 to 200 nm. There is known a method of forming a silicon dioxide film, and then covering the ITO film.

[0003]

However, in the above-mentioned prior art, since the alkali elution preventing film and the transparent conductive film are covered with the dipping equipment and the vacuum film forming equipment, respectively, the inter-process There are problems such as defects such as scratches and glass edge chipping that are indispensable for glass transportation, large equipment space is required, an operator is required for each process, etc.
It has been difficult to efficiently produce transparent conductive glass with a high yield. Further, it is known that the presence of sodium ions in the glass is not preferable in ensuring the reliability of the liquid crystal display element, and a transparent conductive glass having a more alkaline elution prevention performance is required. It has been desired to develop a method for efficiently producing conductive glass.

The present invention has been made in order to solve the above problems, and an object of the present invention is to provide a method for economically producing a conductive glass for a liquid crystal display device having a high alkali prevention performance.

When a liquid crystal display device is manufactured using the above-mentioned transparent conductive glass of the prior art, the transparent conductive glass on which an electrode pattern is processed is usually manufactured by an alignment film treatment step or the like.
Since the glass is subjected to heat treatment at 0 to 480 ° C. for about 30 to 60 minutes, heat shrinkage occurs in the glass at this time, and the size of the glass is slightly reduced, which causes a problem that the electrode pattern is displaced. The displacement of the electrode pattern due to the thermal contraction of the glass has been a problem when manufacturing a high-definition liquid crystal display device with a particularly large display area.
In particular, when the liquid crystal display is performed in color, or when high-definition display is performed even in monochrome display, the line width of the transparent electrode of the liquid crystal display cell becomes as thin as about 100 to 200 μm. At this time, it is necessary that the deviation of the width of the transparent electrode pattern is at least 1/2 to 1/3 or less, and therefore, the heat shrinkage of the glass substrate that normally occurs during the assembly process of the liquid crystal cell is required to be 30 ppm or less. It is said that.

A second object of the present invention is to economically manufacture a transparent conductive glass in which the heat shrinkage of the glass substrate caused by the heat treatment in the liquid crystal display element assembling step is reduced, that is, the electrode pattern is not displaced. To provide a way to do it.

According to the present invention, there is provided a first coating chamber in which a reduced pressure atmosphere can be adjusted and a heating valve in which the reduced pressure atmosphere can be adjusted by connecting the first coating chamber with an openable gate valve. Using an in-line type sputtering apparatus having at least a second coating chamber in which the chamber and the heating chamber are connected by an openable / closable gate valve and the depressurized atmosphere can be adjusted, an alkali elution preventing film and a transparent conductive film are formed on a glass substrate. A method for producing a transparent conductive glass in which films are sequentially coated, comprising: a) setting the temperature of the glass substrate to 2 in the first coating chamber.
Covering the alkali elution preventive film composed of a transparent metal oxide or a transparent metal nitride by sputtering at a temperature of 00 ° C or lower, b) heating the coated alkali elution preventive film to 300 ° C or higher in the heating chamber. To densify, c) coating the transparent conductive film in the second coating chamber in a state where the glass substrate coated with the alkali elution preventing film is heated to 300 ° C. or higher. This is a method for producing a transparent conductive glass for a liquid crystal display element.

The present invention eliminates the case where the alkali elution preventive film and the transparent conductive film are carried out by separate devices, and continuously coats the alkali elution preventive film with a single facility and densifies the alkali elution preventive film. It is characterized in that the step and the step of coating the transparent conductive film are performed.

As the alkali elution preventive film used in the present invention, a transparent metal oxide or a transparent metal nitride, which is transparent in the wavelength range of visible light, is used. Specifically, silicon nitride, tantalum nitride, silicon dioxide, or dioxide is used. Examples include zirconium, tantalum pentoxide, and aluminum oxide. Of these, silicon dioxide is most preferably used. The thickness of these alkali elution preventive films is preferably 10 to 200 nm. If the thickness is 10 nm or less, the alkali elution prevention performance is deteriorated, which is not preferable, and even if the thickness is 200 nm or more, the alkali prevention performance is not improved depending on the thickness of the film.

Particularly, for the silicon dioxide film, 10 to 5
It is preferable because the object can be achieved with a relatively thin thickness of 0 nm. The above alkali elution preventing film can be formed by known high frequency sputtering or direct current reactive sputtering in which a metal target is sputtered in an atmosphere containing oxygen or nitrogen.

When the temperature of the glass plate at the time of coating the alkali elution preventing film is set to 200 ° C. or less, the effect of baking the film in the subsequent densification treatment step is increased and the alkali elution preventing performance is further improved. It is necessary to make it. Setting the temperature of the glass plate to 150 ° C. or lower is more preferable because it suppresses the diffusion of sodium ions in the glass onto the glass surface.

The heat treatment temperature performed in the heating chamber according to the present invention needs to be 300 ° C. or higher. The upper limit of the heating temperature can be set to a temperature at which the flatness of the glass surface is not deteriorated due to the bending or warping of the glass plate. The heating time depends on the thickness of the alkali elution prevention film,
It is determined in relation to the thickness of the transparent conductive film.

In the present invention, the heat shrinkage treatment of the glass plate can be performed simultaneously with the densification treatment of the alkali elution preventive film. The heat shrinkage of the glass is performed by heating the glass of the soda lime silica composition to 380 ° C. or higher. In order to perform the heat shrinkage treatment in a short time, the heating temperature of the glass is preferably 450 ° C. or higher, more preferably 500 ° C. or higher. Further, the atmosphere for the heat shrinkage is a reduced pressure atmosphere.

The heating temperature for the heat shrinkage of the glass plate according to the present invention does not necessarily need to exceed the heating temperature during the process of manufacturing a liquid crystal display device using the glass plate. When a glass plate having a soda lime silica composition is used as the glass substrate, setting the shrinkage ratio of the heat shrinkage in the heating chamber to 50 ppm or more reduces the shrinkage amount of the glass size caused by the heat treatment during the liquid crystal display element manufacturing process. It is preferable that the deviation of the electrode pattern is substantially unlikely to occur, and it is more preferably 150 ppm or more.

The transparent conductive film used in the present invention may be a tin-doped indium oxide (ITO) film, a fluorine- or antimony-doped tin oxide film, or the like. A known method such as high frequency sputtering or direct current reactive sputtering is used for the target. In particular, the ITO film is preferable because it has a low resistivity and the fine electrode can be easily processed.

As a glass plate for a liquid crystal display device, a float glass having a soda lime silica composition (70% to 73% by weight of SiO _{2 and} 1% of Al ₂ O ₃ as main components by weight%) is used.
~ 1.8%, CaO 7-12%, MgO 1-4.5
%, Na ₂ O 13 to 15%, Fe ₂ O ₃ 0.08 to
0.14% included) is most commonly used because it is cheap and available in large quantities. In the present invention, particularly with respect to the glass having the soda lime silica composition, the improvement of the alkali elution prevention performance and the stabilization of the dimension of the glass plate by heat shrinkage can be simultaneously and effectively performed.

Further, it is a so-called low expansion glass having a low expansion coefficient, for example, NA-45 glass manufactured by Hoya Co., AX glass manufactured by Asahi Glass Co., 70 manufactured by Corning Glass Co., Ltd.
A glass substrate such as 59 glass can be used.

EXAMPLES The present invention will be described below based on examples.
1 is a side sectional view of an in-line type sputtering apparatus used for carrying out the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a manufacturing flow chart for explaining a method for manufacturing a transparent conductive glass according to a conventional technique. .. Example The washed and dried soda lime silica composition has a thickness of 1.1.
A mm float glass plate was attached to a metal carrier 13 having upper and lower claws and capable of supporting a glass substrate between them, and set in a vacuum preliminary chamber 1 partitioned by openable and closable gate valves 14A and 14B. The carrier 13 was transferred to the first coating chamber 2 after the inside of the vacuum preliminary chamber 1 became a predetermined depressurized state. The temperature of the glass plate is maintained at 150 ° C. by the heater 9 and the front surface of the quartz glass targets 7, 7 to which high frequency power is applied and is sputtered in an atmosphere of argon gas of 0.4 Pa (Pascal) is set to 0. 45m /
Silicon dioxide (SiO ₂ ) while transporting at the speed of a minute
The film was coated to 35 nm. Further, the carrier 13 is conveyed to the heating chamber 3 by opening / closing the gate valve 14C, and the carrier 13 is driven by the heater 10 and the heater 11.
The temperature of the glass was set to 500 ° C. when the sample was in the heating chamber 13, and the alkali elution preventing film was densified and the glass plate was heat-shrinked. At this time, the atmosphere in the heating chamber is 0.4.
It was set to Pa or less. After that, the gate valve 14 that can be opened and closed
Open D, convey the carrier 13 into the second coating chamber 4, adjust the glass plate temperature to 400 ° C. by the heater 11A and the heater 12, and add oxygen 1% argon 9
Cathodes 8, 8 and 8 to which an ITO (mixture of 10% tin oxide and 90% indium oxide) target, which is sputtered by applying DC power in a reduced pressure atmosphere of 9% of 0.3 Pa, is attached. 0.45m in front of 8
While transporting at a speed of / min, the ITO film is 150 nm
Coated. After that, the gate valve 14E that can be opened and closed, 1
By operating 4F and 14G, the carrier 13 is sequentially transferred from the second coating chamber 4 to the buffer chamber 5 and the take-out chamber 6 without changing the decompressed atmosphere state of the second coating chamber, and finally in-line sputtering is performed. Device 15 to carrier 1
3 was taken out.

The visible light transmittance of the obtained transparent conductive glass was 90%, and the sheet resistance of the ITO film was 8 ohm / square. After the ITO film of this glass was removed by etching with an acid, it was immersed in boiling pure water at 100 ° C. for 24 hours, the amount of alkali in this pure water was quantified, and the alkali elution prevention performance was measured. Was / cm ² . The heat shrinkage rate of the transparent conductive glass when it was heat-treated in the atmosphere at 480 ° C. for 30 minutes was 26.5.
It was ppm. Comparative Example 1 A washed and dried float glass plate having a soda-lime-silica composition having a thickness of 1.1 mm was immersed in an aqueous solution of silicofluoric acid, and a SiO ₂ film was coated to a thickness of 35 nm at 35 ° C. On the SiO ₂ film of this glass, with the same device used in the example,
Except that the SiO ₂ film was not coated in the first coating chamber and that the heater 11 was not used for heating,
The ITO film was coated in the same manner as in the example.

The transparent conductive glass obtained had a visible light transmittance of 90%, and the ITO film had a sheet resistance of 8 ohms / square. After the ITO film of this glass was removed by etching with an acid, it was immersed in boiling pure water at 100 ° C. for 24 hours, the amount of alkali in this pure water was quantified, and the alkali elution prevention performance was measured. / Cm ² and the alkali elution prevention performance were reduced to 1/5 of those of the examples. The heat shrinkage rate of the transparent conductive glass was 48.3 ppm when heat-treated at 480 ° C. for 30 minutes in the atmosphere. Comparative Example 2 A transparent conductive glass was manufactured in exactly the same manner as in Example except that the heater 11 in the heating chamber 3 was not powered.

The visible light transmittance of the obtained transparent conductive glass was 90%, and the sheet resistance of the transparent conductive film was 8 ohm / square. After the ITO film of this glass was removed by etching with an acid, it was immersed in boiling pure water at 100 ° C. for 24 hours and the amount of alkali in this pure water was quantified to measure the alkali elution prevention performance. As a result, the alkali elution prevention performance was about 1 μg / cm ^2, which was 1/5 to 1/10 that of the examples. The heat shrinkage rate of the transparent conductive glass when it is heat-treated in the atmosphere at 480 ° C. for 30 minutes is 4
It was 2.6 ppm.

As described above, the transparent conductive glass obtained in the examples is 1/5 to 1 / th of that obtained in the comparative examples.
It can be seen that the alkali elution amount is as low as 10. Furthermore, even if the transparent conductive glass obtained in the example is subjected to heat treatment in the atmosphere for 30 minutes at 480 ° C., which is almost the same heat treatment condition as received in the liquid crystal display element manufacturing process (liquid crystal cell assembling process), It can be seen that the heat shrinkage was suppressed to 30 ppm or less, and the heat shrinkage was greatly reduced as compared with the transparent conductive glass obtained in Comparative Example.

[0021]

According to the present invention, a glass plate can be continuously coated with an undercoat having an excellent alkali elution preventing property and a low resistance transparent conductive film, so that a liquid crystal display device can be obtained. It is possible to efficiently manufacture the transparent conductive glass for use with high yield. Further, since the densification of the coated alkali elution preventing film and the heat shrinkage treatment of the glass plate can be performed at the same time, the heat shrinkage amount of the glass in the heat treatment during the liquid crystal display element manufacturing process is reduced, and the pattern shift of the transparent electrode is reduced. It is possible to efficiently manufacture a transparent conductive glass that does not cause a phenomenon with a single facility.

[Brief description of drawings]

FIG. 1 is a side sectional view of an in-line type sputtering apparatus used for carrying out the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a manufacturing flowchart for explaining a conventional technique.

[Explanation of Codes] 1 ... vacuum reserve chamber, 2 ... first coating chamber, 3 ...
Heating chamber, 4 ... second coating chamber, 5 ... buffer chamber,
6 ... take-out chamber, 7, 8 ... cathode, 9, 1
0, 11, 11A, 12 ... Heater, 13 ... Carrier, 14 ... Gate valve, 15 ... In-line type sputtering device

Claims (5)

[Claims] 1. A first coating chamber in which the reduced pressure atmosphere can be adjusted and the first coating chamber are connected by a gate valve that can be opened and closed, and a heating chamber in which the reduced pressure atmosphere can be adjusted and the heating chamber are opened and closed. A transparent conductive film in which an alkali elution-preventing film and a transparent conductive film are sequentially coated on a glass substrate by using an in-line type sputtering device which has at least a second coating chamber which is connected by a gate valve and is capable of adjusting a depressurized atmosphere. A method for producing glass, comprising: a) setting the temperature of the glass substrate to 2 in the first coating chamber.
Covering the alkali elution preventive film composed of a transparent metal oxide or a transparent metal nitride by sputtering at a temperature of 00 ° C or lower, b) heating the coated alkali elution preventive film to 300 ° C or higher in the heating chamber. To densify, c) coating the transparent conductive film in the second coating chamber in a state where the glass substrate coated with the alkali elution preventing film is heated to 300 ° C. or higher. A method for producing a transparent conductive glass for a liquid crystal display device. 2. Heating the glass plate in the heating chamber
The method according to claim 1, wherein the alkali elution preventing film is densified and the glass substrate is thermally contracted at the same time by setting the temperature to 0 ° C. or higher. 3. The alkali elution preventive film comprises 10 to 200
3. The method according to claim 1 or 2, characterized in that it is silicon dioxide with a thickness of nm. 4. The method according to claim 2, wherein the glass substrate is a glass plate having a soda lime silica composition, and the heat shrinkage rate is 50 ppm or more. 5. The method according to claim 1, wherein the transparent conductive film is a tin-doped indium oxide film.