Method of making a fluoride crystalline optical lithography lens element blank
US7204942B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 25, 2003 |
| Grant date | Apr 17, 2007 |
| Priority date | — |
| Expiry date | Nov 25, 2023 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S501/90
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The method of making a high quality fluoride crystalline optical microlithography lens element blank includes crystallizing a fluoride crystalline member with dimension ≧200 mm from a melt, annealing the fluoride crystalline member and qualifying the resulting member for use as an optical microlithography lens element blank The fluoride crystalline optical lithography lens element blanks have multiple adjoining abutting crystalline subgrains with low boundary angles. The crystalline members made by the method are qualified for use as lens element blanks by a testing method including measuring their absorption spectra at 200 to 220 nm to determine absorbance at 205 nm and/or by making measurements of radiation diffracted by them.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.