Angstrom polishing of calcium fluoride optical VUV microlithography lens elements and preforms
US6375551B1 · kind B1 · utility
9Cited by
4References
56Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 6, 2000 |
| Grant date | Apr 23, 2002 |
| Priority date | — |
| Expiry date | Jun 6, 2020 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC30B33/00
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
The invention provides a means for making below 200 nm VUV optical microlithography lens elements and preforms therefor. The inventive methods include polishing a fluoride optical lithography crystal with cerium to a surface roughness less than five angstroms. The invention includes making a 157 nm VUV optical lithography element preform by polishing a calcium fluoride crystal with cerium oxide polish.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.