Error Analysis of the Geometric Self-Calibration of the Grating Interferometer System for the Wafer Stage

Geometric self-calibration of the grating interferometer system is essential to improve the displacement measurement accuracy of the wafer stage, and the error analysis is critical for geometric self-calibration. The self-calibration idea based on the self-consistency of a redundant system and the step-by-step self-calibration method of the grating interferometer system for the wafer stage are briefly introduced. The error sources destroying the self-consistency of the geometric mathematical model are analyzed and transformed into the phase shift errors caused by non-geometric errors. The relationship between the accuracy of the model after self-calibration and the phase shift errors is established by fitting the simulation data and can be used as a basis for the design and accuracy budget of the self-calibration process of the grating interferometer system for the wafer stage.