Method for producing a blank of fluorine-doped and titanium-doped glass having a high silicic-acid content and a blank produced according to the method

US9568818B2 · kind B2 · utility

Assignee

• HERAEUS QUARZGLAS GMBH & CO. KG · DE

Inventors

• Stefan Ochs · Bad Camberg, DE
• Klaus Becker · Hanau, DE

Key dates

• Filing date: Sep 23, 2015
• Grant date: Feb 14, 2017
• Expiry date: Sep 23, 2035

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03C2203/54
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A method for producing a silica glass blank co-doped with titanium and fluorine for use in EUV lithography includes (a) producing a TiO2—SiO2 soot body by flame hydrolysis of silicon- and titanium-containing precursor substances, (b) fluorinating the TiO2—SiO2 soot body to form a fluorine-doped TiO2—SiO2 soot body, (c) treating the fluorine-doped TiO2—SiO2 soot body in a water vapor-containing atmosphere to form a conditioned soot body, and (d) vitrifying the conditioned soot body to form the blank. The blank has an internal transmission of at least 60% in the wavelength range of 400 to 700 nm at a sample thickness of 10 mm, a mean OH content in the range of 10 to 100 wt. ppm and a mean fluorine content in the range of 2,500 to 10,000 wt. ppm. Titanium is present in the blank in the oxidation forms Ti3+ and Ti4+.