Low-order Wavefront Error Compensation for Multi-field of Lithography Projection Objective Based on Interior Point Method

Abstract

Low-order wavefront error account for a large proportion of wave aberrations. A compensation method for low order aberration of projection lithography objective based on Interior Point Method is presented. Compensation model between wavefront error and degree of movable lens freedom is established. Converting over-determined system to underdetermined system, the compensation is solved by Interior Point Method (IPM). The presented method is compared with direct solve the over-determined system. Then, other algorithm GA, EA and PS is compared with IPM. Simulation and experimental results show that the presented compensation method can obtained compensation with less residuals compared with direct solve the over-determined system. Also, the presented compensation method can reduce computation time and obtain results with less residuals compare with AGA, EA and PS. Moreover, after compensation, RMS of wavefront error of the experimental lithography projection objective decrease from 56.05 nm to 17.88 nm.