KrF深紫外光刻投影物镜光机热集成分析与优化

Opto-Mechanical Thermal Integration Analysis and Optimization of KrF Deep Ultraviolet Lithography Projection Lens

提出了一种融合新型支撑方式与灵敏度分析的光机热集成分析与优化方法,用于设计超高精度深紫外光刻投影物镜系统。首先,采用轴向多点与周向三点胶接支撑相结合的新型支撑方式,实现了212.51 mm口径光学元件的超高精度定位要求。其次,通过对光学元件进行热力耦合分析,验证了光机系统的合理性。然后,在光机热集成分析条件下,分析了单个光学元件的灵敏度,以及全部光学元件表面变形对整体光学系统波像差均方根值和校准F-tanθ(F为焦距,θ为物方视场角)畸变的影响。最后,通过调整部分光学元件的灵敏度进行局部优化,并对整体光学系统的像质进行优化。结果表明:在热力耦合条件(参考温度为22.5℃、极限工作温度为±2.5℃、重力)下,光学元件的最大表面面型均方根(RMS)值为9.86 nm,能够满足超高精度定位要求。在光机热集成分析条件下(参考温度为22.5℃、极限工作温度为±2℃、重力),优化后光学系统的波像差RMS值小于10.50 nm,校准F-tanθ畸变小于6.00 nm,相较于优化前,波像差RMS提升了46.98%,校准F-tanθ畸变提升了77.69%,达到了设计要求。

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 optomechanical 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-tanθdistortion 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-tanθdistortion 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-tanθdistortion shows an impressive enhancement of 77.69%,successfully meeting the design specifications.