High repetition-rate LPP-source facility for EUVL

Abstract

In this work we present the status of our high repetition-rate/high power EUV source facility. The mass-limited target concept has demonstrated high conversion efficiencies (CE) previously, with precision solid state lasers. Currently, experiments are in progress with high power high repetition-rate (3-4 kHz) Q-switched laser modules. We present a new dedicated facility for the high power EUV source. Also, we present a precision EUV energy-meter, which is developed for absolute EUV energy measurements. Spectral measurements of the tin-doped droplet laser plasma are performed with a flat-field spectrometer (FFS) with a back-illuminated CCD camera. We address the issue of maintaining the calibration of the EUV optics during source operation at non-optimum intensity at high repetition-rate, which is required for CE improvement studies. Here we present the unique metrology for measuring EUV energies under a variety of irradiation conditions without degrading EUV optics, even at high repetition rates (multi-kHz). Show more