Patent ID: 7084084

Claim:
A durable silica glass member provided in a semiconductor production apparatus or a liquid crystal production apparatus, which is exposed to a fluorine-containing gas or a plasma of halogenated gas, comprising a durable silica glass consisting essentially of SiO 2 , Al 2 O 3 and an oxide of at least one element (M) selected from the group consisting of group 3A elements of the periodic table, wherein said silica glass has an amorphous structure and further has a composition falling within a hexagon formed by drawing lines connecting six points: 70:20:10, 50:20:30, 30:40:30, 30:50:20, 45:50:5 and 70:25:5, in the triangular diagram of three-components Si—Al—M, and wherein said silica glass is free of nitrogen.