| 摘要 |
PURPOSE:To produce quartz glass which has little Ti impurities and excellent in the transmittance of ultraviolet light by using silicon alkoxide and fine powdery silica as a raw material and producing quartz by a sol-gel process. CONSTITUTION:Ethanol, water and aq. ammonia are added to unpurified ethyl silicate having 0.02ppm Ti content of harmful impurities and the mixture is stirred and left to stand overnight and concentrated to make it sol. On the other hand, 0.02 N hydrochloric acid is added to unpurified ethyl silicate and this mixture is hydrolyzed to form sol. After mixing both the above-mentioned sols and stirring this mixture, aq. ammonia is added thereto to regulate pH to 4.5. Then this sol is introduced into a polypropylene vessel and allowed to gel and thereafter the obtained gel is dried at 60 deg.C for 10 days to produce dry gel. After sintering this to produced quartz glass, this is subjected to high temp. treatment at 1,780 deg.C for 10min. The obtained quartz glass has <=0.05ppm Ti content and >=90% transmittance of ultraviolet light having 200nm wavelength and can be sufficiently used as the substrate of a photomask for an IC. |
