Fluorine control system for excimer lasers
US5978406A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 30, 1998 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Jan 30, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S3/225
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An excimer laser with a laser gas containing fluorine in which the fluorine concentration is maintained continuously at or substantially at desired predetermined levels. A real time or substantially real time fluorine monitor provides a feedback signal to a fluorine flow control system which provides continuous fluorine injection flow into the laser chamber to precisely compensate for fluorine depletion and maintain fluorine concentration precisely at desired levels. In a preferred embodiment, fluorine detector which may be a chemical detector periodically measures the fluorine concentration in laser gas discharged from the laser in order to calibrate the real time or substantially real time fluorine monitor. In a second preferred embodiment, the continuous inlet flow is from two gas sources, one containing fluorine, a noble gas and a buffer gas and the other containing only the noble gas and the buffer gas. In a third embodiment, the continuous inlet flow is from a gas source containing fluorine, a noble gas and a buffer gas and filtered gas discharged from the laser.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.