Method of refining rare gas fluoride excimer laser gas
US4964137A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 18, 1990 |
| Grant date | Oct 16, 1990 |
| Priority date | — |
| Expiry date | Jan 18, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S3/225
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A laser gas used in a rare gas fluoride excimer laser is efficiently refined with little loss of the principal rare gas such as Ar, Kr or Xe by sequential contact of the laser gas first with a reactive metal, e.g. Si or Fe, for conversion of the fluorine source gas such as F.sub.2 or NF.sub.3 to a metal fluoride, then with a solid alkaline compound, e.g. Ca(OH).sub.2, for conversion of gaseous fluorides to solid metal fluorides, next with zeolite which is adsorbent of most of the remaining impurities and finally with an alkaline metal, e.g. Ca or Na, for decomposition of CF.sub.4 to form a solid metal fluoride and carbon. CF.sub.4 is formed during operation of the excimer laser by reaction of fluorine with a fluororesin used as electrical insulator in the laser apparatus, and accumulation of CF.sub.4 in the laser gas caused significal lowering of the laser output power.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.