15 March 2016 Confocal position alignment in high-precision wavefront error metrology using Shack-Hartmann wavefront sensor
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Abstract
The aberration inspection of Shack-Hartmann of lithographic lens has reached the nanometer inspection accuracy. Collimator as the key element of the system, the accurate positioning of itself is one important factor for the inspection accuracy. Based on the wavefront reconstruction with Zernike polynomials, in this paper, an optical alignment method for positioning adjustments of the collimator is presented. A sensitivity matrix is obtained from the equation that describes the correlation between Zernike coefficients and the multi-degree-of-freedom misalignment, and the positioning adjustments of collimator are acquired thereof. For the aberration inspection with Shack-Hartmann method, an engineering model of 193nm NA 0.75 projection lens is established in commercial simulating software (ZEMAX). For 0.5nm RMS aberration inspection accuracy, the positioning accuracy of collimator is analyzed and plotted with independent single freedom degree and mutual correlation with combined three freedom degrees. These analysis indicate the proposed method is a viable tool for aligning confocal position of collimator.
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Jiani Su, Jiani Su, Zengxiong Lu, Zengxiong Lu, Yuejing Qi, Yuejing Qi, Guangyi Liu, Guangyi Liu, Qingbin Meng, Qingbin Meng, "Confocal position alignment in high-precision wavefront error metrology using Shack-Hartmann wavefront sensor", Proc. SPIE 9780, Optical Microlithography XXIX, 97801N (15 March 2016); doi: 10.1117/12.2218506; https://doi.org/10.1117/12.2218506
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