Tosoh Corporation

Tosoh Sgm Corporation

Masahito Uchida

Kazuyoshi Arai

Yoshinori Harada

Tsutomu Takahata

Nobusuke Yamada

Hideharu Horikoshi

Shinkichi Hasimoto

Fused silica glass having an internal transmittance of UV with 245 nm wavelength, being at least 95% at 10 mm thickness, a OH content of not larger than 5 ppm, and a content of Li, Na, K, Mg, Ca and Cu each being smaller than 0.1 ppm. Preferably the glass has a viscosity coefficient at 1215&#xb0; C. of at least 10Pa&#xb7;s; and a Cu ion diffusion coefficient of not larger than 1&#xd7;10cm/sec in a depth range of greater than 20 &#x3bc;m up to 100 &#x3bc;m, from the surface, when leaving to stand at 1050&#xb0; C. in air for 24 hours. The glass is made by cristobalitizing powdery silica raw material; then, fusing the cristobalitized silica material in a non-reducing atmosphere. The glass exhibits a high transmittance of ultraviolet, visible and infrared rays, has high purity and heat resistance, and exhibits a reduced diffusion rate of metal impurities, therefore, it is suitable for various optical goods, semiconductor-production apparatus members, and liquid crystal display production apparatus members.

Fused silica glass and process for producing the same

Growing community of inventors

Yokohama, Japan

Masahito Uchida