JPS6385029A - Glass attached with coating film to prevent dissolution of alkali metal and production thereof - Google Patents

Abstract

PURPOSE:To obtain a glass having a pinhole-free dense transparent coating film for preventing the dissolution of alkali metal, by attaching a coating film composed mainly of a mixture of Al2O3 and SiO2 on the surface of a glass containing alkali metal. CONSTITUTION:The glass of the present invention has a transparent surface- coating film for the prevention of alkali metal dissolution and composed of 40-60atom% Al2O3 and 40-60atom% SiO2. The objective glass can be produced by the following process. The above transparent coating film is applied to a surface of glass containing alkali metal by a reactive DC sputtering technique using a metal target composed mainly of a mixture of preferably Al and Si. The composition of the metal target is preferably those having the above atom%. The transparent coating film produced by the above process is resistant to the corrosion with alkali metal migrated from the glass surface and is effective in preventing the migration of the alkali metal to the surface of the coating film.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to glass coated with an alkali metal elution prevention coating;
The present invention relates to a glass coated with an alkali metal elution prevention coating suitable for use as a substrate for transparent electrodes used in liquid crystal display devices, and a method for manufacturing the same.

[Conventional technology]

Glass substrates are used as transparent electrodes for displays such as liquid crystal display panels and hard mask substrates in the semiconductor wafer field. It is desirable to use quartz glass or the like having a stable surface as these glass substrates, but it is expensive, so inexpensive plate glass containing an alkali metal such as sodium is often used.

Glass containing alkali metals such as sodium dissolves on its surface over a long period of time, so liquid crystal display panels using such glass substrates may suffer from damage to the transparent electrodes or conductive current flowing between the liquid crystal electrodes. The display function of the liquid crystal deteriorates, and hard masks using such difficult glass substrates deteriorate the performance of the mask film.

In order to prevent the elution of alkali metals from glass containing alkali metals, a transparent film containing silicon oxide as a main component was formed on the glass surface. This transparent coating for preventing alkali metal elution, which is mainly composed of silicon oxide, coats glass with ethyl silicate 6.
After the glass surface was immersed in an ethyl alcohol solution of the glass to adhere the solution to the glass surface, it was heated to form a transparent film containing silicon oxide as the main component. The silicon oxide film formed by such a dipping method is porous and tends to have pinholes, so it has the disadvantage that it is less effective in preventing alkali metal elution.

Therefore, in order to obtain a sufficient effect of preventing elution of alkali metals, it is necessary to form a silicon oxide film of ionm or more. Therefore, when attempting to form a silicon oxide film as an alkali metal elution prevention film using a sputtering method instead of a dipping method, the target surface is oxidized, whereas in the DC sputtering method, reactive sputtering is performed using conductive silicon as a target. , sputtering becomes unstable, making it difficult to form a film, and high-frequency sputtering uses quartz glass as a target, but it is difficult to uniformly apply a high-frequency electric field to a large target, so it is difficult to apply a high-frequency electric field uniformly to a large target. The drawback is that it is difficult to form a uniform silicon oxide film, and the use of a high-output high-frequency power supply causes radio wave interference, and the silicon oxide insulating film that adheres to the inner surface of the vacuum chamber. The drawbacks include a decrease in the deposition rate over time due to changes in the electric field distribution of the plasma.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned drawbacks. The purpose is to manufacture it industrially and at low cost.

[Means for solving problems]

That is, the present invention is a glass in which a transparent coating for preventing alkali metal elution, which is mainly composed of a mixture of aluminum oxide and silicon oxide, is adhered to the surface of glass containing an alkali metal.

In the present invention, the transparent coating for preventing alkali metal elution is preferably attached to the surface of the glass by reactive direct current sputtering using a metal target mainly composed of a mixture of aluminum and silicon. Aluminum oxide (AJ20
3) is J Oatm% to R o atml, and silicon oxide (Sing) is used in a composition of 20 atm% to 10 atm%. In particular, aluminum oxide (Al2O3), which has a refractive index similar to that of the glass substrate, is IIO atm%.
to go atm%, and silicon oxide (Si02) is ≠o
It is preferable to use one having a composition of atm% to to atm<.

[For production]

In the present invention, a transparent coating mainly composed of a mixture of aluminum oxide and silicon oxide is attached to the surface of glass containing an alkali metal, so that the transparent coating is not damaged by the alkali metal from the glass surface. The alkali metal does not dissolve on the surface.

In particular, by forming a dense pinhole-free transparent film containing a mixture of aluminum oxide and silicon oxide as the main ingredients, using a reactive sputtering method using a metal target containing a mixture of aluminum and silicon as the main ingredients. It has a remarkable effect of inhibiting the elution of alkali metals from the glass surface.
After depressurizing the inside of the vacuum chamber 1 to 4 Pa using an oil diffusion pump (not shown) through the exhaust port 2, the gas introduction pipe 7 is passed into the vacuum chamber 1.
Introducing a mixed gas of 0% by volume of argon and 30% by volume, adjusting the pressure inside the tank to a pressure of #X#7-IPa,
A power supply 9 is applied to a target B, which is a sintered powder mixture of aluminum and silicon, on which a magnet is placed on top of the target. Sputtering is performed by applying a negative voltage of jKV, and the glass layer is moved above the target 5 using a conveyor P-rug, and a transparent film for preventing alkali metal elution made of a mixture of aluminum oxide and silicon oxide is formed on the lower surface of the glass 5. It stuck.

Target 6 is aluminum! Oatm%~≦Q
Atm%, Silico"7 is llo atm% to r o
At'm% of various compositions are used, and various compositions of aluminum oxide and silicon oxide as shown in Table 1 are used.
A coating with a thickness of 20 nm or ionm was formed.

Table 1: Each sample obtained was immersed in warm water of WAJ'C for 241 hours,
The amount of Na eluted from the coating surface was determined.

In addition, the refractive index of the coating of each sample was measured using an Elibson meter. The results of these measurements are shown in Table 1. As a comparative example, a glass with a silicon oxide film of 100 nm thick was prepared on the surface of soda lime glass by the immersion method described above, and the Na+ ffj eluted from the film surface and the refractive index were measured. As shown in the table, the amount of alkaline elution is O
, SS μg/crl refractive index was /, <1.

〔Effect of the invention〕

As is clear from Table 1, the glass with the alkali metal elution prevention transparent coating according to the present invention has a lower alkali elution amount than the conventional alkali metal elution prevention glass with the transparent coating.
(l or less, and the refractive index of soda lime glass /,
! ; closer to 2/, t7 to /, j7, and was excellent as a substrate for liquid crystal display panels and the like.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view showing a sputtering apparatus according to an embodiment of the present invention. l: Vacuum chamber, 2: Exhaust port, 3: Vacuum chamber wall, t: Conveyor roll, 5 Ni glass, 6: Target, 7: Gas introduction tube, Z: Magnet Figure 1

Claims (3)

[Claims] (1) A glass containing an alkali metal with a transparent coating that prevents elution of alkali metals and whose main components are a mixture of aluminum oxide and silicon oxide attached to the surface of the glass. (2) The transparent thin film is aluminum oxide (Al_2O_3
) is 40 to 60 atm % and silicon oxide (SiO_2) is 40 to 60 atm %, the glass having a transparent coating for preventing alkali metal elution according to claim 1 attached. (3) Using a metal target mainly composed of a mixture of aluminum and silicon, the surface of glass containing alkali metal is coated with a transparent material containing a mixture of aluminum oxide and silicon oxide to prevent elution of alkali metals, using a reactive direct current sputtering method. Method of applying coating.