13.5 nm波长极紫外(EUV)光刻机的分辨率虽然很高,但因波长的减小使其对像差的容忍度降低,有必要研究像差对EUV光刻成像的影响。针对四类典型像差的波前特征,选取对像差最敏感的四种测试图形,研究像差对光刻成像特征尺寸和最佳聚焦点偏差量的影响。在满足焦深要求的条件下,给出各单类像差的最大允许范围,最后将四类像差总值控制在0.04λ内,从仿真分析的角度研究了实际工艺生产对像差的要求,即总像差需控制在0.025λ以内,约0.34 nm。

In comparison with traditional immersion lithography, extreme ultraviolet (EUV) lithography at a wavelength of 13.5 nm has become a promising technology. While imaging resolution has been greatly improved, aberration tolerances must be strengthened as they scale with wavelength, and a greater understanding of the effect of aberration on EUV lithography imaging is urgently needed. Focusing on the wave front characteristics of four kinds of typical aberrations, this study establishes corresponding aberration models according to their characteristics to explore the influence of aberration on lithographic imaging critical dimension and best focus bias. The maximum allowable range of single aberrations under required focus depths is provided. The total values of the four kinds of aberrations are controlled within 0.04λ, and the analysis is repeated to determine the requirements the aberrations needed in actual demand from the simulation. Based on these results, total aberrations should be controlled within 0.025λ, about 0.34 nm.