Homogeneity improvement of TiO2-SiO2 glass synthesized by the soot method and its evaluation using the ultrasonic measurement system

Masahiro Kawagishi, Junko Konishi, Masaaki Takata, Mototaka Arakawa, Yuji Ohashi, Jun Ichi Kushibiki

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


TiO2-SiO2 glass is one of the leading candidates for optical elements of extreme ultraviolet lithography. TiO2-SiO 2 glass synthesized by the soot method has shown striae related to inhomogeneity of TiO2 concentration formed in the planes perpendicular to soot growth direction in the synthesis process. It can induce CTE variation and localized surface roughness. Striae were characterized in three modes by polarization microscope. Such striae were improved with an improved gas condition and developing a modified material gas supply system. Specimen prepared from the improved TiO2-SiO2 glass was evaluated by a line-focus-beam ultrasonic material characterization system, using a surfaceacoustic- wave mode. Improved glass had 43% striae level compared to conventional glass by birefringence measurement, 31% compared to conventional glass by the ultrasonic measurement. It was found that improved glass had good homogeneity to both directions perpendicular and parallel to striae plane.

Original languageEnglish
Title of host publicationExtreme Ultraviolet (EUV) Lithography IV
Publication statusPublished - 2013
EventExtreme Ultraviolet (EUV) Lithography IV - San Jose, CA, United States
Duration: 2013 Feb 252013 Feb 28

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


OtherExtreme Ultraviolet (EUV) Lithography IV
Country/TerritoryUnited States
CitySan Jose, CA


  • EUVL
  • Homogeneity
  • Leaky surface acoustic waves
  • Line-focus-beam ultrasonic material characterization system
  • Optical material
  • Soot method
  • Striae
  • TiO-SiO glass

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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