由于光刻投影物镜小比率模型光学系统的光学元件数量较多,用每个补偿量去补偿对应失调量的传统装调方法已不适用.本文利用灵敏度矩阵,通过找出偏心补偿量和倾斜补偿量的内在联系来缩小补偿量的选择范围.然后根据失调量敏感度的分析,提出了选择系统补偿量的方法.利用这个方法,选择4个补偿量便使补偿后的光学系统成像质量满足设计指标要求,减少了光学系统的装调难度.最后,编写宏模块完成大量仿真计算,验证了敏感度分析的正确性.光学系统初装完成后,对系统进行了预装调.实验结果表明,补偿后系统波像差(RMS)由50.9 nm提高到25.9 nm,优于技术指标要求,证明了本文提出的补偿量选择方法的正确性和有效性.
As the small scale model optical system for a projected objective of lithography has so many optical elements,it is impossible to use a traditional method that each compensator only compensates the corresponding misalignment.Therefore,this paper proposes a sensitive matrix to solve this problem.Firstly,the internal relations between the decenter disalignments and the tip/tilt ones were found out based on a sensitive matrix to reduce the range of selection compensators.Then,according to the analysis of the disalignment sensitivity,a method for selecting system compensators was proposed.With the method,only selected four compensators could allow the imaging quality of compensated optical system to achieve the design index and the alignment difficulty to be reduced.Finally,the macro command modes were proposed to complete the massive simulation calculation to prove the correctness of the sensitive analysis.After the original assembling,a pre-aligning procedure of optical system was achieved to ensure the feasibility of the aligning scheme.The test results show that the wave front errors (RMS) have reduced to 25.9 nm from 50.9 nm after compensation,which is better than the requirements of the qualifications.The results prove that the proposed methods are right and effective.