JP3232646B2 - Method for producing transparent conductive glass for liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive glass in which an alkali elution preventing film and a transparent conductive film are sequentially coated on a glass plate, and in particular, to a liquid crystal display element using a float glass of soda lime silica composition as a glass substrate. The present invention relates to a method for producing a suitably used transparent conductive glass.

[0002]

2. Description of the Related Art A transparent conductive glass for a simple matrix type liquid crystal display element is provided with an alkali elution preventing film as an undercoat on a float glass plate of soda lime silica composition, and ITO (tin) doped as a transparent conductive film. One coated with an indium oxide (indium oxide) film is known. As a method of manufacturing the above-mentioned transparent conductive glass, a washed glass plate is immersed in a silicic acid solution and about 35 mm is placed on the glass plate.
An alkali elution preventing film made of a silicon dioxide film having a thickness of about 50 nm is coated at a room temperature (step 1 in FIG. 3), and then the glass is washed again (step 2 in FIG. 3). A method of coating an ITO film by step 3) is known. Further, instead of the above-mentioned silicic acid solution, the glass plate is immersed in a diluent of an organic silicon compound such as polysiloxane, and then the glass plate is heated in the air to decompose and remove organic components to have a thickness of 100 to 200 nm. There is known a method of forming a silicon dioxide film, and then coating an ITO film.

[0003]

However, in the above-mentioned prior art, the coating of the alkali elution preventing film and the coating of the transparent conductive film require a dipping facility and a vacuum film-forming facility, respectively. There are problems that defects such as scratches and chipping of the glass edge, which are indispensable for the transportation of glass, are likely to occur, large equipment space is required, and workers are required for each process,
It has been difficult to produce a transparent conductive glass efficiently and with a high yield. Further, the presence of sodium ions in the glass is known to be unfavorable in securing the reliability of the liquid crystal display element, and a transparent conductive glass having a more alkaline elution preventing performance is required, and such a transparent conductive glass is required. It has been desired to develop a method for efficiently producing conductive glass.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a method for economically producing a conductive glass for a liquid crystal display element having a high alkali prevention performance.

When a liquid crystal display device is manufactured using the above-described conventional transparent conductive glass, the transparent conductive glass on which an electrode pattern has been processed is usually subjected to an alignment film processing step or the like.
Since the glass is subjected to a heat treatment at 0 to 480 ° C. for about 30 to 60 minutes, there is a problem in that heat shrinkage occurs in the glass at this time, and the glass size is slightly reduced, thereby causing a shift in the electrode pattern. The displacement of the electrode pattern due to the heat shrinkage of the glass has been a problem particularly when manufacturing a high-definition liquid crystal display element with a large display area.
In particular, when performing liquid crystal display in color, or when performing high-definition display 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 to make the deviation of the width of the transparent electrode pattern at least 1/2 to 1/3 or less, and therefore, it is necessary to reduce the heat shrinkage of the glass substrate during the assembly process of the liquid crystal cell to 30 ppm or less. It has been.

A second object of the present invention is to reduce the thermal shrinkage of the glass substrate caused by the heat treatment in the liquid crystal display element assembling step, that is, to produce a transparent conductive glass with no electrode pattern deviation economically. Is to provide a way to do that.

SUMMARY OF THE INVENTION According to the present invention, there is provided a first coating chamber in which a reduced-pressure atmosphere can be adjusted, and a first coating chamber in which the reduced-pressure atmosphere can be adjusted by a gate valve which can be opened and closed. The chamber and the heating chamber are connected by a gate valve that can be opened and closed, and an alkali elution preventing film and a transparent conductive film are formed on a glass substrate by using an in-line sputtering apparatus having at least a second coating chamber in which a reduced-pressure atmosphere can be adjusted. A method for producing a transparent conductive glass in which a film is sequentially coated, comprising: a) in the first coating chamber, the temperature of the glass substrate is set to 2;
Coating the alkali elution prevention film made of a transparent metal oxide or a transparent metal nitride by sputtering at a temperature not higher than 00 ° C., b) heating the coated alkali elution prevention film to 300 ° C. or higher in the heating chamber. C) in the second coating chamber, coating the transparent conductive film in a state where the glass substrate coated with the alkali elution preventing film is heated to 300 ° C. or more. This is a method for producing a transparent conductive glass for a liquid crystal display element.

[0007] The present invention eliminates the need for performing the alkali elution preventing film and the transparent conductive film in separate devices, and continuously coats the alkali elution preventing film with a single facility and densifies the alkali elution preventing film. And a step of coating the transparent conductive film.

As the alkali elution preventing film used in the present invention, a transparent metal oxide or a transparent metal nitride which is transparent in the wavelength region of visible light is used, and specifically, silicon nitride, tantalum nitride, silicon dioxide, and silicon dioxide Examples include zirconium, tantalum pentoxide, and aluminum oxide. Among these, silicon dioxide is most preferably used. The thickness of these alkali elution preventing films is preferably 10 to 200 nm. When the thickness is 10 nm or less, the alkali elution prevention performance is undesirably reduced, so that even if the coating is applied to a thickness of 200 nm or more, the alkali prevention performance does not improve according to the thickness of the film.

In particular, for silicon dioxide films, 10 to 5
It is preferable because the object can be achieved with a relatively thin thickness of 0 nm. The 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 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 let It is more preferable to set the temperature of the glass plate to 150 ° C. or less, because it suppresses sodium ions in the glass from diffusing to the glass surface.

[0011] The heat treatment temperature in the heating chamber according to the present invention must be 300 ° C or higher. The upper limit of the heating temperature can be a temperature at which the flatness of the glass surface is not impaired by bending or warping of the glass plate. The heating time depends on the thickness of the alkali elution preventing film,
It is determined in relation to the thickness of the transparent conductive film.

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

The heating temperature for 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 element using the glass plate. When a glass plate having a soda-lime-silica composition is used for 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 dimension caused by the heat treatment during the liquid crystal display element manufacturing process. This is preferable in that the displacement of the electrode pattern is substantially unlikely to occur, and more preferably 150 ppm or more.

As the transparent conductive film used in the present invention, a tin-doped indium oxide (ITO) film, a fluorine- or antimony-doped tin oxide film, or the like is used. Known methods such as high-frequency sputtering and DC reactive sputtering are used for the target. In particular, an ITO film is preferable because it has a low resistivity and the processing of fine electrodes is easy.

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

Also, so-called low expansion glass having a low expansion coefficient, for example, NA-45 glass (trade name, manufactured by Hoya Corporation), AX glass manufactured by Asahi Glass Co., Ltd., 70 glass manufactured by Corning Glass Co., Ltd.
A glass substrate such as 59 glass can be used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
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 of FIG. 1, and FIG. 3 is a manufacturing flowchart for explaining a conventional method for manufacturing a transparent conductive glass. . Example The thickness of the washed and dried soda lime silica composition was 1.1.
A float glass plate having a thickness of 2 mm was attached to a metal carrier 13 having upper and lower claws and capable of supporting a glass substrate therebetween, and was set in a vacuum preliminary chamber 1 partitioned by gate valves 14A and 14B which can be opened and closed. The carrier 13 was moved to the first coating chamber 2 after the inside of the vacuum preparatory chamber 1 reached a predetermined reduced pressure state. The temperature of the glass plate was maintained at 150 ° C. by the heater 9, and the front surfaces of the quartz glass targets 7, which had been sputtered by applying high frequency power under an atmosphere of 0.4 Pa (Pascal) of argon gas, were set to 0.1 mm. 45m /
Silicon dioxide (SiO ₂ )
The film was coated at 35 nm. Further, the carrier 13 is transported to the heating chamber 3 by opening and closing the gate valve 14C, and the carrier 13 is heated by the heaters 10 and 11.
Was placed in the heating chamber 13, the temperature of the glass was set to 500 ° C., and the alkali elution preventing film was densified and the glass plate was thermally shrunk. At this time, the atmosphere in the heating chamber was 0.4
Pa or less. Then, the gate valve 14 that can be opened and closed
D is opened, the carrier 13 is transported into the second coating chamber 4, and the temperature of the glass plate is adjusted to 400 ° C. by the heaters 11A and 12 to adjust the oxygen 1% argon 9
The cathodes 8, 8, 8, and 9 attached with an ITO (mixture of 10% tin oxide and 90% indium oxide) target to which DC power is applied under a reduced pressure atmosphere of 9% and 0.3 Pa and sputtered. 0.45m front of 8
While transporting the ITO film at a speed of 150 nm / min.
Coated. Thereafter, the gate valves 14E, 1
By operating the 4F and 14G, the carrier 13 is sequentially transferred from the second coating chamber 4 to the buffer chamber 5 and the removal chamber 6 without changing the depressurized atmosphere state of the second coating chamber. Carrier 1 from device 15
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 the glass was removed by etching with an acid, the glass was immersed in boiling pure water at 100 ° C. for 24 hours, and the amount of alkali in the pure water was quantified. / Cm ² . When the transparent conductive glass was subjected to a heat treatment in the atmosphere at 480 ° C. for 30 minutes, the heat shrinkage of the glass was 26.5.
ppm. Comparative Example 1 A float glass plate having a thickness of 1.1 mm of a washed and dried soda lime silica composition was immersed in an aqueous solution of silicic acid and coated with a 35 nm SiO ₂ film at 35 ° C. On the SiO ₂ film of this glass, using the same apparatus as used in the examples,
Except that the SiO ₂ film was not coated in the first coating chamber and heating by the heater 11 was not performed,
The ITO film was coated in the same manner as in the example.

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, the glass was immersed in boiling pure water at 100 ° C. for 24 hours, the amount of alkali in the pure water was quantified, and the alkali elution prevention performance was measured. / Cm ² and the alkali elution prevention performance was reduced to 1/5 of the example. When the transparent conductive glass was subjected to a heat treatment at 480 ° C. for 30 minutes in the air, the heat shrinkage of the glass was 48.3 ppm. Comparative Example 2 A transparent conductive glass was produced in exactly the same manner as in the example except that power was not supplied to the heater 11 of the heating chamber 3.

The resulting transparent conductive glass had a visible light transmittance of 90% and a sheet resistance of the transparent conductive film of 8 ohm / square. After the ITO film of this glass was removed by etching with an acid, the glass was immersed in boiling pure water at 100 ° C. for 24 hours, and the amount of alkali in the pure water was quantified.性能0.1 μg / cm ^2, and the alkali elution prevention performance was reduced to 1/5 to 1/10 of that of the examples. When the transparent conductive glass was subjected to a heat treatment in the atmosphere at 480 ° C. for 30 minutes, the heat shrinkage of the glass was 2.6 ppm.

As described above, the transparent conductive glass obtained in the example is 1/5 to 1/1/1 that of the transparent conductive glass obtained in the comparative example.
It can be seen that the alkali elution amount is as low as 10. Furthermore, the transparent conductive glass obtained in the example was subjected to a heat treatment in the air at 480 ° C. for 30 minutes, which is almost the same heat treatment conditions as those 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 significantly reduced as compared with the transparent conductive glass obtained in Comparative Example.

[0021]

According to the present invention, an undercoat having excellent alkali elution preventing performance and a low-resistance transparent conductive film can be continuously coated on a glass plate with a single facility, so that a liquid crystal display device is provided. Transparent conductive glass can be efficiently produced at a 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 simultaneously, the amount of heat shrinkage of the glass during the heat treatment during the liquid crystal display element manufacturing process is reduced, and the pattern shift of the transparent electrode is performed. The transparent conductive glass free from the occurrence of the problem can be efficiently manufactured with a single facility.

[Brief description of the 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 of FIG.

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

[Explanation of symbols]

1 ... vacuum spare 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1333 G02F 1/13 101 G02F 1/1343 G02F 1/1362 G09F 9/00-9/46 B65G 49 / 00

Claims (5)

(57) [Claims] 1. A first coating chamber in which a reduced-pressure atmosphere can be adjusted and the first coating chamber are connected by a gate valve which can be opened and closed, and a heating chamber in which a 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 apparatus having at least a second coating chamber connected with a possible gate valve and capable of adjusting a reduced-pressure atmosphere. A method for producing glass, comprising: a) in the first coating chamber, the temperature of the glass substrate is set to 2;
Coating the alkali elution prevention film made of a transparent metal oxide or a transparent metal nitride by sputtering at a temperature not higher than 00 ° C., b) heating the coated alkali elution prevention film to 300 ° C. or higher in the heating chamber. C) in the second coating chamber, coating the transparent conductive film in a state where the glass substrate coated with the alkali elution preventing film is heated to 300 ° C. or more. A method for producing a transparent conductive glass for a liquid crystal display element. 2. The heating of the glass plate in the heating chamber is performed by 38.
2. The method according to claim 1, wherein at a temperature of 0 ° C. or higher, densification of the alkali elution preventing film and heat shrinkage of the glass substrate are simultaneously performed. 3. The method according to claim 1, wherein the alkali elution preventing film is 10 to 200.
3. The method according to claim 1, wherein the silicon dioxide has 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 is 50 ppm or more. 5. The method according to claim 1, wherein the transparent conductive film is an indium oxide film doped with tin.