Patent ID: 9238243
Filing Date: 2016-01-19
CPC Classification: B05B,G03F,H05G,H05H

Claim Text:
1. A method of pre-compensating for push-out from a primary focal spot at which sequential target material droplets from a droplet generator are to be lased during burst-firing of an extreme ultraviolet laser light source, the laser light source containing a feedback mechanism for correcting for droplet-to-droplet changes in axial position, comprising: sensing a plurality of droplets during a burst, the droplets directed toward an initial target position; calculating an axial position for each of the sensed droplets; estimating for each sensed droplet an uncorrected droplet position by subtracting from the calculated axial position for each of the droplets any correction in axial position made by the feedback mechanism; calculating, after the burst has ended, a pre-compensation correction based on the uncorrected droplet positions; calculating an updated target position based upon the pre-compensation correction; and commanding one or more actuators to reposition the droplet generator to deliver, during a succeeding burst, droplets of target material to the updated target position.