PRODUCTION OF SAPPHIRE SUBSTRATE FOR PHOTOMASK

摘要

PURPOSE: To obtain a method for producing the sapphire substrate for a sapphire glass photomask high in mechanical and chemical durability. CONSTITUTION: A single crystal of sapphire is formed from alumina (Al2 O3 ) in Step 101. The formed sapphire single crystal is cut to a square sheet of sapphire in accordance with the size and thickness of a necessary photomask in Step 102. The periphery of the square sapphire sheet is finished with a periphery reshaping machine in Step 103. The surface of the square sheet with the periphery reshaped is polished. Both sides are polished at the same time or the one side after another is polished in Step 104. The square sapphire sheet with the surface polished is cleaned in Step 105.