Photomask substrate made of synthetic quartz glass and photomask
US7491475B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 3, 2006 |
| Grant date | Feb 17, 2009 |
| Priority date | — |
| Expiry date | Aug 15, 2027 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/31616
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
It is to provide a photomask substrate which has a low birefringence and with which polarized illumination can be employed or immersion exposure can be carried out.A photomask substrate made of a synthetic quartz glass to be used for production of a semiconductor employing a light source having an exposure wavelength of at most about 200 nm, which has a birefringence of at most 1 nm/6.35 mm at the exposure wavelength, and of which the amount of decrease in light transmittance is at most 1.0% as a difference in light transmittance at a wavelength of 217 nm, between before and after irradiation with Xe excimer lamp with an illuminance of 13.2 mW/cm2 for 20 minutes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.