Shin-Etsu Chemical Co., Ltd.

Masanobu Ezaki

Hisatoshi Otsuka

Shigeru Maida

Tetsuji Ueda

On an EUV light-reflecting surface of titania-doped quartz glass, an angle (&#x3b8;) included between a straight line connecting an origin (O) at the center of the reflecting surface to a birefringence measurement point (A) and a fast axis of birefringence at the measurement point (A) has an average value of more than 45 degrees. Since fast axes of birefringence are distributed in a concentric fashion, a titania-doped quartz glass substrate having a high flatness is obtainable which is suited for use in the EUV lithography.

Titania-doped quartz glass and making method

Methods for selecting titania-doped quartz glass which experiences a reduction in OH group concentration of less than or equal to 100 ppm upon heat treatment at 900&#xb0; C. for 100 hours as suitable material for the EUV lithography member.

Titania doped quartz glass and making method

A member is made of titania-doped quartz glass in which striae have a curvature radius of at least 150 mm in a surface perpendicular to an EUV-reflecting surface. The member free of exposed striae and having a high flatness is useful in EUV lithography.

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Koriyama, Japan

Masanobu Ezaki