随着极紫外(EUV)光刻物镜的设计朝着组合倍率物镜系统的方向发展,物镜系统需要同时具有大视场和高数值孔径(NA),因而产生了物镜的光线入射角及入射角范围急剧增大的问题,需要研究适用于组合倍率极紫外光刻物镜系统的膜层设计的新方法。提出了渐进优化膜层的设计方法,该方法提高了镀制膜层的物镜系统的反射率,保证了组合倍率物镜系统的成像质量。利用该方法对NA为0.6的组合倍率物镜系统进行了膜层设计,设计结果表明,含膜极紫外光刻物镜系统的平均反射率大于65%,各反射镜的反射率峰谷值均小于3.35%,反射率均匀性良好。

The development of extreme ultraviolet(EUV) lithographic objective design is toward the direction of an anamorphic magnification objective system, and large field of view and high numerical aperture (NA) for projection objectives are both needed, which cause an extreme increase of incident angle and incident angle range of an objective lens system, so new methods for multilayer film design of anamorphic magnification EUV lithography objective systems are needed to explore. A progressive optimization multilayer film design method is presented to increase the reflectivity but not to change the imaging performance. This method is successfully applied to design the multilayer films of an anamorphic magnification EUV lithography objective system with NA=0.6. The results show that the average reflectivity of each mirror is higher than 65% and the reflectivity peak-to-valley value of each mirror is less than 3.35%, meanwhile, a good uniformity of reflectivity is maintained.