MELTED QUARTZ GLASS AND METHOD FOR MANUFACTURING THE SAME

• Main Authors: TAKAHATA TSUTOMU, YAMADA SHUSUKE, UCHIDA MASATO, HARADA YOSHINORI, HORIKOSHI HIDEHARU, ARAI KAZUYOSHI, HASHIMOTO SHINKICHI
• Format: Patent
• Language: English
• Published: 16.01.2014
• Subjects: CHEMICAL COMPOSITION OF GLASSES, GLAZES, OR VITREOUSENAMELS; CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GLASS; JOINING GLASS TO GLASS OR OTHER MATERIALS; MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES; METALLURGY; MINERAL OR SLAG WOOL; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS,MINERALS OR SLAGS; SURFACE TREATMENT OF GLASS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE

PROBLEM TO BE SOLVED: To inexpensively provide a melted quartz glass which is suitably usable for various optical materials that use ultraviolet rays, visible rays and infrared rays, a member for manufacturing a semiconductor, a member for manufacturing a liquid crystal, a member for manufacturing MEMS, and a glass substrate for a liquid crystal, has a high transmittance to ultraviolet rays, visible rays and infrared rays, has high purity and high heat resistance, and a low diffusion speed of a Cu ion.SOLUTION: In a melted quartz glass, an internal transmittance to ultraviolet light having a wavelength of 245 nm in a thickness of 10 mm is 95% or more, an OH content is 5 ppm or less, and each content of Li, Na, K, Mg, Ca and Cu is less than 0.1 ppm. Preferably, Al is contained therein in weight ratio of 2 ppm or less, the viscosity at 1,215°C is 10Pa s or more, and a diffusion coefficient of a Cu ion in a depth of 20 to 100 μm from the surface in thermal diffusion of the Cu ion at 1,050°C in the atmosphere is 1×10cm/sec or less. Such a melted quartz glass can be obtained by previously converting raw material silica powder into cristobalite, and then melting the cristobalitized silica powder in a non-reducing atmosphere.