Millen White Zelano & Branigan, P.C.
Glass substrate for photomasks and preparation method
A glass substrate is to be used as a photomask having a patterned light-shielding film on a surface thereof and thus exposed to light. The substrate is leveled by local plasma etching such that an exposure surface may have a flatness of 0.04-2.2 nm/cm2. Since the glass substrate is configured such that the exposure surface or hold surface of the resulting photomask is fully flat during the exposure step, it is suited for use as silica glass substrates for photomasks used in the photolithography of great interest in the fabrication of ICs, thus contributing to the achievement of finer patterns in the semiconductor field.
Shin-Etsu Chemical Co., Ltd.
C G C
C03C G03F C03C
inventional inventional inventional
Yukio Masaki
Shibano Takeuchi