VERFAHREN ZUR HERSTELLUNG EINES SUBSTRATS AUS SYNTHETISCHEM QUARZGLAS FÜR EINE PHOTOMASKE

摘要

A synthetic quartz glass substrate is prepared by annealing a synthetic quartz glass member having a higher hydroxyl content in a peripheral portion than in a central portion, machining off the peripheral portion of the member, slicing the member into a plate shaped substrate, chamfering and etching the substrate. The synthetic quartz glass substrate has a minimized birefringence and is suited for use as a photomask in photolithography.