Titania-doped quartz glass and making method

Patent metadata

Field	Value
Publication number	US-10114280-B2
Application number	US-201615041113-A
Country	US
Kind code	B2
Filing date	Feb 11, 2016
Priority date	Apr 11, 2011
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

On an EUV light-reflecting surface of titania-doped quartz glass, an angle (θ) included between a straight line connecting an origin (O) at the center of the reflecting surface to a birefringence measurement point (A) and a fast axis of birefringence at the measurement point (A) has an average value of more than 45 degrees. Since fast axes of birefringence are distributed in a concentric fashion, a titania-doped quartz glass substrate having a high flatness is obtainable which is suited for use in the EUV lithography.

First claim

The invention claimed is:

1. A titania-doped quartz glass having a surface where EUV light is reflected, wherein an angle (θ) included between a straight line connecting an origin (O) at the center of the reflecting surface and a birefringence measurement point (A) and a fast axis of birefringence at the measurement point (A) has an average value of more than 45 degrees, and wherein the fast axes of birefringence in the EUV light reflecting surface are distributed in a concentric fashion.

2. The titania-doped quartz glass of claim 1 wherein on the EUV light-reflecting surface, a standard deviation of birefringence is less than or equal to 5 nm/cm.

3. The titania-doped quartz glass of claim 1 wherein on the EUV light-reflecting surface, a maximum of birefringence is less than or equal to 10 nm/cm.

4. The titania-doped quartz glass of claim 1 , having a fictive temperature distribution of less than or equal to 20° C.

5. The titania-doped quartz glass of claim 1 , having a fictive temperature of lower than or equal to 850° C.

6. An EUV lithographic member comprising the titania-doped quartz glass of claim 1 .

7. The EUV lithographic member of claim 6 which is an EUV lithographic photomask substrate.

8. The EUV lithographic photomask substrate of claim 7 wherein the substrate has front and back surfaces, either one of which has a flatness of less than or equal to 50 nm in a central region of 142 mm×142 mm squares.

9. The EUV lithographic photomask substrate of claim 8 wherein both the front and back surfaces have a flatness of less than or equal to 50 nm in a central region of 142 mm×142 mm squares.

Assignees

• Shinetsu Chemical Co

Inventors

• Maida Shigeru
• Otsuka Hisatoshi
• Ueda Tetsuji
• Ezaki Masanobu

Classifications

• C03C2203/42

  using silicon halides as starting materials · CPC title

• C03B19/1423

  Reactant deposition burners · CPC title

• C03B19/1415 Primary

  Reactant delivery systems · CPC title

• C03B2201/42

  doped with titanium · CPC title

• C03C4/08

  for glass selectively absorbing radiation of specified wave lengths · CPC title