Birch, Stewart, Kolasch & Birch, LLP
Photomask-forming glass substrate and making method
A photomask-forming glass substrate having a square major surface is provided wherein two strip regions are defined on the major surface near a pair of opposed sides such that each region spans between 2 mm and 10 mm inward of the side and excludes end portions extending 2 mm inward from the opposed ends of the side, a least squares plane is computed for each of the two strip regions, the angle included between normal lines to the least squares planes of two strip regions is within 10 seconds, and the height difference between two strip regions is up to 0.5 μm.
SHIN-ETSU CHEMICAL CO., LTD.
G Y G
G03F Y10T G03F
inventional additional inventional
Daijitsu Masaki Yukio Mamoru
Harada Takeuchi Shibano Morikawa