Asahi Glass Company, Limited

Long Shao

Akio Koike

Shinya Kikugawa

Yasutomi Iwahashi

Tomonori Ogawa

Masaaki Takata

Kenta Saito

Kei Iwata

The present invention provides a synthetic silica glass for an optical member in which not only a fast axis direction in an optical axis direction is controlled, and a birefringence in an off-axis direction is reduced, but a magnitude of a birefringence in the optical axis direction is controlled to an arbitrary value, such that an average value of a value BR cos2&#x3b8;defined from a birefringence BR and a fast axis direction &#x3b8;as measured from a parallel direction to the principal optical axis direction is defined as an average birefringence AveBR cos2&#x3b8;, and when a maximum value of a birefringence measured from a vertical direction to the principal optical axis direction of the optical member is defined as a maximum birefringence BRin an off-axis direction, the following expression (1-1) and expression (2-1) are established:&#x2212;1.0&#x2266;AveBR cos2&#x3b8;&#x3c;0.0&#x2003;&#x2003;(1-1)0.0&#x2266;BR&#x2266;1.0&#x2003;&#x2003;(2-1).

Synthesized silica glass for optical component

The present invention provides a TiO&#x2014;SiOglass whose coefficient of linear thermal expansion in the range of the time of irradiation with EUV light is substantially zero when used as an optical member of an exposure tool for EUVL and which has extremely high surface smoothness. The present invention relates to a TiO-containing silica glass having a TiOcontent of from 7.5 to 12% by mass, a temperature at which a coefficient of linear thermal expansion is 0 ppb/&#xb0; C., falling within the range of from 40 to 110&#xb0; C., and a standard deviation (&#x3c3;) of a stress level of striae of 0.03 MPa or lower within an area of 30 mm&#xd7;30 mm in at least one plane.

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Growing community of inventors

Tokyo, Japan

Long Shao