Cristobalite-contained silica glass, and silica glass jig made of same

摘要

An object of the present invention is to provide silica glass having high purity, high heat resistance, large coefficient of thermal expansion, and low light transmittanc. Another object of the present invention is to provide a silica glass jig with a vapor-deposited film thereon. Therfore Cristobalite-contained silica glass wherein alpha -cristobalite in the shape of a small sphere or a small, round-edged or sharp-edged, three-dimensional region is dispersed in the silica glass matrix, the diameter of each alpha -cristobalite sphere or region is in the range of 0.1 mu m to 1000 mu m, a content of the alpha -cristobalite is at least 10 wt %, and small-sized independent bubbles which are additionally dispersed in the silica glass matrix. The silica glass jig is made of the cristobalite-contained silica glass and the surface of the jig is covered with a vapor-deposited thin film which has a property of being resistant to plasma etching, and which is made of a material of almost the same coefficient of thermal expansion as that of the silica glass. The silica glass jig has no chance to generate particles therefrom and thereby to contaminate a silicon wafer.