Patent ID: 9713239
Date: 2017-07-18
CPC Classifications: G03F,H05G

Claim:
1. An EUV light source comprising: a system for generating a plurality of targets; a system generating pre-pulses and main-pulses, the pre-pulses for irradiating targets to produce expanded targets, the system comprising a continuously pumped laser device generating the main pulses, the main pulses for irradiating expanded targets to produce a burst of EUV light pulses, the system having a controller varying at least one pre-pulse parameter during the burst of EUV light pulses; and metrology instrument operatively coupled with said controller for measuring an intensity of at least a portion of one EUV light pulse within the burst of EUV light pulses generated by main pulses irradiation and for generating a feedback signal responsive to the measuring and for providing the feedback signal to the controller for varying responsive to the feedback signal at least one pre-pulse parameter, wherein the measuring, the providing feedback signal, and the varying occur during the burst of EUV light pulses.