Monitoring of spectral purity and advanced spectral characteristics of a narrow bandwidth excimer laser

摘要

An on-board diagnostic tool can be used to monitor the spectral purity of a lithography laser, such as an excimer or molecular fluorine laser, instead of simply measuring the FWHM bandwidth of the laser. One such on-board tool utilizes a Fabry-Perot Interferometer etalon with a high-finesse and a small free spectral range, which provides the precision necessary to determine spectral purity, while providing the small footprint and light weight necessary to use the tool on-board. A high signal-to-noise detector can be used to improve the accuracy of the measurements.