Fishing – trapping – and vermin destroying
Patent
1992-06-23
1994-07-05
Kunemund, Robert
Fishing, trapping, and vermin destroying
148DIG101, 423335, 4274301, 427169, B05D 118
Patent
active
053267206
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for producing silicon dioxide film, and more particularly to an improved method for producing a silicon dioxide film on the surface of a substrate by contacting the substrate with a treating liquid comprising a hydrosilicofluoric acid solution supersaturated with silicon dioxide.
Conventionally, as a method for forming a silicon dioxide film, there is known a method wherein a silicon dioxide film is formed on the surface of a substrate by dipping the substrate such as glass into an aqueous solution of hydrosilicofluoric acid supersaturated with silicon dioxide (hereinafter referred to as deposition method) (for example, Japanese Unexamined Patent Publication Nos. 196744/1982, 281047/1986 and 20876/1987). For increasing the film deposition rate in the deposition method, it is effective to increase the feed rate of a material or heat energy which accelerates the decomposition of hydrosilicofluoric acid as the treating liquid. However, it is known that if the feed rate is too fast, silicon dioxide particles are produced in the treating liquid and the film deposition rate is rather decreased. This means that the film forming efficiency represented by a ratio of (the amount of silicon dioxide film formed)/(the amount of material or heat energy which accelerates decomposition of hydrosilicofluoric acid) (hereinafter referred to as film forming efficiency) is decreased. In order to inhibit generation and growth of silicon dioxide particles and to increase the film deposition rate (namely, to increase the film forming efficiency), it is known to continuously feed the material or heat energy which accelerates decomposition of hydrosilicofluoric acid, and to circulate a part of the treating liquid so as to filter out silicon dioxide particles (hereinafter referred to as improved method 1) (for example, Japanese Unexamined Patent Publication Nos 33233/1985 and 102738/1988).
Also, as a manner of forming a dense silicon dioxide film in the above-mentioned deposition method, there are known a method wherein a silicon dioxide film is formed at a high temperature of treating liquid (hereinafter referred to as improved method 2) (for example, Japanese Patent Application No. 184569/1987); and a method wherein a high concentration of hydrosilicofluoric acid solution is used as the treating liquid (hereinafter referred to as improved method 3) (for example, Japanese Patent Application No. 174561/1987).
However, the film deposition rate obtained by the improved method 1, is from about 30 to about 100 nm/h, although it varies somewhat depending on the treating conditions, so it is not sufficient from the industrial point of view. Further, even in the improved method 1, generation of silicon dioxide particles occurs, so the film forming efficiency is not necessarily enough.
In the improved methods 2 and 3, Si components (presumed to be H.sub.2 SiF.sub.6 or SiF.sub.4) evaporate vigorously from the treating liquid, so silicon dioxide particles deposit at the interface between the treating liquid and the atmosphere, or to the wall of a vessel at the positions above the surface of the treating liquid. These silicon dioxide particles are estimated to be originally a part able to form a silicon dioxide film in the treating liquid, but escape into the atmosphere, so that there arises a problem that the film forming efficiency decreases. In addition, the evaporation of the treating liquid into the atmosphere is undesirable because the working environment is polluted.
DISCLOSURE OF THE INVENTION
The present invention has been made in order to solve the above-mentioned problems. The present invention relates to a method for producing a silicon dioxide film by contacting a substrate with a treating liquid comprising a hydrosilicofluoric acid solution supersaturated with silicon dioxide and depositing a silicon dioxide film on the surface of the substrate, wherein a means for preventing an Si component from escaping from the treating liquid is provided.
One of the means for preve
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Deki Shigehito
Goda Takuji
Hishinuma Akihiro
Kawahara Hideo
Sakai Yasuto
Horton Ken
Kunemund Robert
Nippon Sheet Glass Co. Ltd.
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