Asahi Glass Company, Limited

Takahiro Mitsumori

Akio Koike

Takeru Kinoshita

Yasutomi Iwahashi

Hirotoshi Ise

Tomonori Ogawa

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/mm.

Glass substrate-holding tool and method for producing an EUV mask blank by employing the same

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 &#x3bc;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.

The present invention relates to a process for production of a TiO&#x2014;SiOglass body, comprising a step of, when an annealing point of a TiO&#x2014;SiOglass body after transparent vitrification is taken as T(&#xb0; C.), holding the glass body after transparent vitrification in a temperature region of from T&#x2212;90(&#xb0; C.) to T&#x2212;220(&#xb0; C.) for 120 hours or more.

[object Object]

A process for producing a porous quartz glass body containing hydrolyzing a metal dopant precursor and an SiOprecursor 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 SiOprecursor gas, (C) one gas of Hand O, and (D) one or more gases selected from the group consisting of a rare gas, N, CO, a hydrogen halide and HO, with a proportion of the gas (D) being from 5 to 70 mol %; and (E) the other gas of Hand Oof (C), are fed into different nozzles of the burner from each other.

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Tokyo, Japan

Takahiro Mitsumori