LOW THERMAL EXPANSION GLASS FOR EUVL APPLICATION

PROBLEM TO BE SOLVED: To provide a low thermal expansion glass which has stable thermal expansion in a temperature range wider than that in the present ULE glass and can be polished so as to satisfy surface roughness requirements. SOLUTION: The low thermal expansion glass includes a base glass material 3 having a front surface 5, a back surface 7, and a thickness T; and a glass coating material 9 applied on at least the front surface 5 of the base glass material 3. The base glass material 3 consists essentially of 10 wt.% to 20 wt.% titania and 80 wt.% to 90 wt.% silica. The glass coating material 9 also consists essentially of titania and silica, but the total amount of titania in the glass coating material 9 is lower than the total amount of titania in the base glass material 3. The base glass material 3 preferably has a coefficient of thermal expansion of substantially zero in the temperature range of about 10 to 100°C. COPYRIGHT: (C)2011,JPO&INPIT