| 摘要 |
PURPOSE:To enlarge the life of a quartz glass plate to be used for the manufacture of semiconductor by a method wherein the surface of the quartz glass plate is so formed as to have the length from the end faces to be less than 20mm., and to have the difference between the maximum and the minimum roughness per measured length of 3mm. to be 30mum or less. CONSTITUTION:When the quartz glass plate before use has previously a minute crack, the crack grows and is enlarged still more by the stress acting to the glass during use. Therefore the surface within the range less than 20mm. from the edge is polished to make to be smooth. When the length exceeds 20mm., it is not economical. The roughness of the polished surface is so made as the difference between the maximum and the minimum per 3mm. to be 30mum or less. When it exceeds 30mum, the number of times to be usable is reduced. The roughness is measured with a surface roughness measuring apparatus, and the roughness between the maximum and the minimum is obtained from the height of chart. Besides the polishing, to melt the unevenness with an oxyhydrogen gas burner after rough polishing to form a smooth surface may do. By this constitution, even if the quartz glass plate is used repeatedly, the crack does not generated and the life is prolonged. |
