Patent ID: 9025130
Filing Date: 2015-05-05
Classification: G02B,G03F

Abstract:
1. A method comprising: directing a beam of radiation, with optics of a lithography tool, along an optical axis toward a workpiece support, the optics of the lithography tool having a longitudinal aberration; measuring, at a first time, a first spectral profile of the beam and also a first peak intensity of the beam; measuring, at a second time subsequent to the first time, a second spectral profile of the beam and also a second peak intensity of the beam; calculating a spectral offset between the first and second spectral profiles; calculating a peak intensity offset between the first peak intensity and the second peak intensity; calculating an adjustment amount by multiplying the spectral offset by the longitudinal aberration; and adjusting a position of the workpiece support along the optical axis by an average of the adjustment amount and the peak intensity offset.