Shin-etsu Chemical Co., Ltd.

Shin-etsu Chemical C O., Ltd.

Yoko Ishitsuka

Masaki Takeuchi

Atsushi Watabe

Daijitsu Harada

A large-size synthetic quartz glass substrate has a diagonal length of at least 1,000 mm. Provided that an effective range is defined on the substrate surface, and the effective range is partitioned into a plurality of evaluation regions such that the evaluation regions partly overlap each other, a flatness in each evaluation region is up to 3 &#x3bc;m. From the quartz glass substrate having a high flatness and a minimal local gradient within the substrate surface, a large-size photomask is prepared.

Large-size synthetic quartz glass substrate, evaluation method, and manufacturing method

The invention provides a method for producing a synthetic quartz glass substrate, the method includes arranging spacers to be in contact with outer peripheral side surfaces of a synthetic quartz glass substrate, arranging plate materials to be in contact with the outer peripheral side surfaces of the spacers in a state that the plates are protruded from the surface of the substrate, and sandblasting the surface of the substrate.

Method for producing synthetic quartz glass substrate

Synthetic quartz glass substrates are prepared by furnishing a synthetic quartz glass block, coating two opposed surfaces of the glass block with a liquid having a transmittance of at least 99.0%/mm at a birefringence measuring wavelength, measuring a birefringence of the glass block by directing light thereacross, determining a slice thickness on the basis of the birefringence measurement and the dimensions of the substrate, and slicing the glass block at the determined slice thickness.

Method for preparing synthetic quartz glass substrate

There is furnished a working tool comprising a rotating shaft (), a polishing plate () mounted on the shaft, an expandable elastomer sheet () attached to the polishing plate (), an abrasive cloth () attached to the elastomer sheet (), and means for pressing the elastomer sheet () at a plurality of positions under respective predetermined different pressures such that a lower surface of the abrasive cloth () is deformed to the desired inverted convex shape in accordance with differences of pressing force applied to the elastomer sheet () at the plurality of positions. A substrate is produced by bringing the inverted convexly deformed surface of the abrasive cloth () in contact with a substrate stock, and rotating and moving the working tool for polishing the substrate over a selected area.

Growing community of inventors

Joetsu, Japan

Yoko Ishitsuka