Abstract: A glass substrate-holding tool employed during the production of a reflective mask blank for EUV lithography includes an electrostatic chuck and a mechanical chuck. A caught and held portion of a glass substrate caught and held by the electrostatic chuck, and pressed portions of the glass substrate pressed by the mechanical chuck are located outside a quality-guaranteed region on each of a film deposition surface and a rear surface of the glass substrate. The sum of a catching and holding force applied to the glass substrate by the electrostatic chuck and a holding force applied to the glass substrate by the mechanical chuck is at least 200 kgf. A pressing force per unit area applied to the glass substrate by the mechanical chuck is at most 25 kgf/mm2.

Abstract: A glass substrate-holding tool, adapted to be employed during the production of a reflective mask blank for EUV lithography (EUVL), includes an electrostatic chuck and a supporting member. The chuck attracts a rear surface of a glass substrate in a non-contact manner by electrostatic attractive force. The supporting member partly supports the rear surface. An area ratio of a projected area of an active surface of the chuck for providing the electrostatic force to an area of a quality-guaranteed region of the rear surface is from 0.5 to 1.0. The active surface is apart from the rear surface by more than 20 ?m. The supporting member is configured to support only a region including at least two of four sides defining an outer portion outside the quality-guaranteed region.

Abstract: The present invention relates to a process for production of a TiO2—SiO2 glass body, comprising a step of, when an annealing point of a TiO2—SiO2 glass body after transparent vitrification is taken as T1(° C.), holding the glass body after transparent vitrification in a temperature region of from T1?90(° C.) to T1?220(° C.) for 120 hours or more.

Abstract: The present invention relates to a process for production of a TiO2—SiO2 glass body, comprising: a step of, when an annealing point of a TiO2—SiO2 glass body after transparent vitrification is taken as T1 (° C.), heating the glass body after transparent vitrification at a temperature of T1+400° C. or more for 20 hours or more; and a step of cooling the glass body after the heating step up to T1?400 (° C.) from T1 (° C.) in an average temperature decreasing rate of 10° C./hr or less.

Abstract: A process for producing a porous quartz glass body containing hydrolyzing a metal dopant precursor and an SiO2 precursor in a flame of a burner to form glass fine particles, and depositing and growing the formed glass fine particles on a base material, in which the burner has at least two nozzles, and in which a mixed gas containing (A) a metal dopant precursor gas, (B) an SiO2 precursor gas, (C) one gas of H2 and O2, and (D) one or more gases selected from the group consisting of a rare gas, N2, CO2, a hydrogen halide and H2O, with a proportion of the gas (D) being from 5 to 70 mol %; and (E) the other gas of H2 and O2 of (C), are fed into different nozzles of the burner from each other.

Abstract: A glass substrate-holding tool, adapted to be employed during the production of a reflective mask blank for EUV lithography (EUVL), includes an electrostatic chuck and a supporting member. The chuck attracts a rear surface of a glass substrate in a non-contact manner by electrostatic attractive force. The supporting member partly supports the rear surface. An area ratio of a projected area of an active surface of the chuck for providing the electrostatic force to an area of a quality-guaranteed region of the rear surface is from 0.5 to 1.0. The active surface is apart from the rear surface by more than 20 ?m. The supporting member is configured to support only a region including at least two of four sides defining an outer portion outside the quality-guaranteed region.

Abstract: The present invention relates to a TiO2-containing silica glass containing TiO2 in an amount of from 5 to 10 mass % and at least one of B2O3, P2O5 and S in an amount of from 50 ppb by mass to 5 mass % in terms of the total content.

Abstract: A glass substrate-holding tool employed during the production of a reflective mask blank for EUV lithography includes an electrostatic chuck and a mechanical chuck. A caught and held portion of a glass substrate caught and held by the electrostatic chuck, and pressed portions of the glass substrate pressed by the mechanical chuck are located outside a quality-guaranteed region on each of a film deposition surface and a rear surface of the glass substrate. The sum of a catching and holding force applied to the glass substrate by the electrostatic chuck and a holding force applied to the glass substrate by the mechanical chuck is at least 200 kgf. A pressing force per unit area applied to the glass substrate by the mechanical chuck is at most 25 kgf/mm2.

Abstract: The present invention relates to a process for production of a TiO2—SiO2 glass body, comprising a step of, when an annealing point of a TiO2—SiO2 glass body after transparent vitrification is taken as T1(° C.), holding the glass body after transparent vitrification in a temperature region of from T1?90(° C.) to T1?220(° C.) for 120 hours or more.

Abstract: The present invention relates to a process for production of a TiO2—SiO2 glass body, comprising: a step of, when an annealing point of a TiO2—SiO2 glass body after transparent vitrification is taken as T1 (° C.), heating the glass body after transparent vitrification at a temperature of T1+400° C. or more for 20 hours or more; and a step of cooling the glass body after the heating step up to T1?400 (° C.) from T1 (° C.) in an average temperature decreasing rate of 10° C./hr or less.

Abstract: The present invention relates to a process for producing a porous quarts glass body containing hydrolyzing a metal dopant precursor and an SiO2 precursor in a flame of a burner to form glass fine particles, and depositing and growing the formed glass fine particles on a base material, in which the burner has at least two nozzles, and in which a mixed gas containing (A) a metal dopant precursor gas, (B) an SiO2 precursor gas, (C) one gas of H2 and O2, and (D) one or more gases selected from the group consisting of a rare gas, N2, CO2, a hydrogen halide and H2O, with a proportion of the gas (D) being from 5 to 70 mol %; and (E) the other gas of H2 and O2 of (C), are fed into different nozzles of the burner from each other.