Abstract: On an EUV light-reflecting surface of titania-doped quartz glass, an angle (?) 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.

Abstract: 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° C. for 100 hours as suitable material for the EUV lithography member.

Abstract: On an EUV light-reflecting surface of titania-doped quartz glass, an angle (?) 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.

Abstract: On an EUV light-reflecting surface of titania-doped quartz glass, an angle (?) 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.

Abstract: 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.

Abstract: 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.

Abstract: 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° C. for 100 hours as suitable material for the EUV lithography member.

Abstract: On an EUV light-reflecting surface of titania-doped quartz glass, an angle (?) 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.

Abstract: A 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° C. for 100 hours is suitable as the EUV lithography member.

Abstract: To provide titania-silica glass which is transparent glass of low thermal expansion, in particular, is of a low thermal expansion coefficient over a wide range of temperatures of 0 to 100° C. (an operating temperature range) when it is used as a photomask or a mirror material in extreme ultraviolet ray lithography, and which is excellent in homogeneity within the field and stability. Titania-silica glass is used which has 8 to 10% by weight of titania and 90 to 92% by weight of silica, where a Ti3+ concentration is 10 to 60 ppm by weight.

Abstract: To provide titania-silica glass which is transparent glass of low thermal expansion, in particular, is of a low thermal expansion coefficient over a wide range of temperatures of 0 to 100° C. (an operating temperature range) when it is used as a photomask or a mirror material in extreme ultraviolet ray lithography, and which is excellent in homogeneity within the field and stability. Titania-silica glass is used which has 8 to 10% by weight of titania and 90 to 92% by weight of silica, where a Ti3+ concentration is 10 to 60 ppm by weight.

Abstract: A silica glass member for semiconductor in which each concentration of Fe, Cu, Cr and Ni is 5 ppb or less and the concentration of an OH group is 30 ppm or less and which has a viscosity of 1013.0 poise or more at 1200° C. is provided as a silica glass member for semiconductor having high heat-resistance and higher purity.

Abstract: The invention provides a method for efficiently manufacturing a synthetic silica glass substrate for photomasks excellent in light stability and capable of being applied to ArF-Wet photolithography with maximum birefringence of 1.4 nm/cm or less, homogeneity of diffractive index of 2×10?5 or less and an average content of hydrogen atoms of 1018 to 1019, comprising the steps of: forming a mask-plain substrate by slicing a block of a synthetic silica glass; heating each sheet of the mask-plain substrate at a temperature of 1100° C. or more; slowly cooling the substrate at a cooling rate of 0.01 to 0.8° C./min; and placing the substrate in a hydrogen gas atmosphere at least at the latter half of the slow cooling step or after the slow cooling step.

Abstract: A silica glass member for semiconductor in which each concentration of Fe, Cu, Cr and Ni is 5 ppb or less and the concentration of an OH group is 30 ppm or less and which has a viscosity of 1013.0 poise or more at 1200° C. is provided as a silica glass member for semiconductor having high heat-resistance and higher purity.