An Optimization Method To Improve Accuracy of the Wavefront Aberration Measurement Technique Based on Principal Component Analysis of Aerial Images

Wavefront aberration of projection lens will deteriorate the lithographic imaging performance, shrink the process window, and depress the yield of chips. The wavefront aberration measurement based on principal component analysis of aerial images (AMAI-PCA) is an efficient technique to solve this problem with the advantages of low cost, high speed and reliable accuracy. To apply this technique to advanced process nodes, this paper proposes an optimization method to improve the accuracy of AMAI-PCA. After obtaining the aberration solution by AMAI-PCA, the BFGS quasi-Newton algorithm is used to further optimize the result. The simulation results show a significant improvement in measurement accuracy.