Opto-Mechanical Thermal Integration Analysis and Optimization of KrF Deep Ultraviolet Lithography Projection Lens
Objective To achieve the design of high-precision deep ultraviolet lithography projection lenses,we propose a method for opto-mechanical thermal integration analysis and optimization of deep ultraviolet lithography projection lenses.This method can analyze the influence of factors such as gravity,mechanical support structure,and temperature variations on the image quality of the optical system during the design phase.A novel support mechanism combining axial multi-point and circumferential three-point adhesive supports is designed to meet the requirements of ultra-high-precision positioning of the optical elements.Meanwhile,sensitivity analysis is conducted on individual optical elements using the sensitivity analysis method to optimize the image quality in opto-mechanical thermal integration analysis conditions,which provides insights and directions for improving the image quality of the optical system.Methods Initially,an innovative support mechanism combining axial multi-point and circumferential three-point adhesive supports is employed to achieve ultra-high precision positioning requirements for a 212.51 mm aperture optical element.Subsequently,the thermal-mechanical coupling analysis of the novel support structure is conducted using the finite element analysis method.The obtained results are adopted in a developed Fringe Zernike polynomial fitting program to compute the surface peak valley(PV)and root mean square(RMS)of the optical element and thus validate the rationality of the opto-mechanical structure.Furthermore,the SigFit software serves as the opto-mechanical interface software,enabling the analysis of individual optical element sensitivity and the influence of overall optical element surface deformations on the wavefront aberration RMS value and calibration of F-tan θ distortion within the opto-mechanical thermal integration analysis framework.Finally,localized optimization is performed on elements with high sensitivity to reduce their sensitivity and ultimately optimize the image quality of the entire optical system.Conclusions In thermal-mechanical coupling conditions(reference temperature of 22.5 ℃,±2.5 ℃,gravitational force),the maximum surface profile RMS value of the optical elements is verified to be ≤9.86 nm,which satisfies the stringent ultra-high precision positioning requirements.In opto-mechanical thermal integration analysis conditions(reference temperature of 22.5 ℃,±2 ℃ limit operating temperature,gravitational force),the optimized wavefront aberration RMS value of the optical system is determined to be 10.50 nm,with a corresponding F-tan θ distortion calibration of 6.00 nm.Compared to pre-optimization results,the wavefront aberration RMS demonstrates a remarkable improvement of 46.98％,while the corresponding F-tan θ distortion shows an impressive enhancement of 77.69％,successfully meeting the design specifications.
optical designstructural designopto-mechanical thermal integration analysisZernike polynomialfinite element analysis
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