Patent · US Active

Method for producing titanium-doped silica glass for use in EUV lithography and blank produced in accordance therewith

US9586850B2 · kind B2 · utility

1Cited by

4References

16Claims

0Family size

Assignee

HERAEUS QUARZGLAS GMBH & CO. KG · DE

Inventors

Stefan Ochs · Bad Camberg, DE
Klaus Becker · Hanau, DE
Stephan Thomas · Großkrotzenburg, DE

Key dates

Filing date	Jul 22, 2014
Grant date	Mar 7, 2017
Priority date	—
Expiry date	Jul 22, 2034

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC03C2204/00
WIPO fieldMaterials, metallurgy
WIPO sectorChemistry

Abstract

The Ti3+ ions present in Ti-doped silica glass cause a brown staining of the glass, causing inspection of the lens to become more difficult. Known methods for reducing Ti3+ ions in favor of Ti4+ ions in Ti-doped silica glass include a sufficiently high proportion of OH-groups and carrying out an oxygen treatment prior to vitrification, which both have disadvantages. In order to provide a cost-efficient production method for Ti-doped silica glass, which at a hydroxyl group content of less than 120 ppm shows an internal transmittance (sample thickness 10 mm) of at least 70% in the wavelength range of 400 nm to 1000 nm, the TiO2—SiO2 soot body is subjected to a conditioning treatment with a nitrogen oxide prior to vitrification. The blank produced in this way from Ti-doped silica glass has the ratio Ti3+/Ti4+≦5×10−4.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.