Narrow band excimer laser
US5982800A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 10, 1997 |
| Grant date | Nov 9, 1999 |
| Priority date | — |
| Expiry date | Oct 10, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S3/2256
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A very narrow band pulse excimer laser capable of producing pulses at a rate in the range of about 500 to 2000 Hz with enhanced energy dose control and reproducibility. A prior art burst mode "slug effect" occuring at one gas circulation time after the beginning of a burst of pulses is eliminated by the addition of a minute quantity of oxygen. In a preferred embodiment very narrow bandwidth is achieved by reducing fluorine partial pressure to less than 0.10 percent and by increasing the reflectance of the output coupler to greater than 25 percent. In a preferred embodiment, prior art fused silica beam expansion prisms used in the prior art line narrowing module were replaced with calcium fluoride prisms.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.