超高数值孔径Schwarzschild投影光刻物镜的光学设计

针对45nm及以下节点光刻相关技术的研究需求,确定了实验型投影光刻物镜的结构型式及设计指标。依据像差理论在非同心小遮拦的Schwarzschild反射系统中添加折射补偿镜组来进一步减小系统的中心遮拦,扩大像方数值孔径。设计了一套小中心遮拦,数值孔径为1.20的Schwarzschild折反式投影光刻物镜。设计结果表明,该投影光刻物镜工作带宽为100pm,像方视场为50μm,线中心遮拦比为13%,光学分辨力为80nm时(6240lp/mm)的系统调制传递函数大于0.45,全视场最大畸变为6.5nm,满足了45nm深紫外(DUV)浸没光刻实验平台对投影光刻物镜的需求。

Optical Design of Hyper Numerical-Aperture Schwarzschild Projection Lithographic Lens

To meet the research requirements of 45 nm node or even below microlithography, the configurations and specifications of experimental lens are determined. Based on the aberration theory, several refractive elements are inserted into a non-concentric all-reflective Schwarzschild system with a small central obstruction so as to achieve smaller obstruction and hyper-numerical aperture. A Schwarzschild catadioptric lithographic lens whose numerical aperture is 1.20 is designed with a small central obstruction. Designing results show that the objective′s working bandwidth is 100 pm, viewing field of image is 50 mm, the linear obstruction ratio is 13%, modulation transfer function is greater than 0.45 at the resolution of 80 nm (6240 lp/mm), and its distortions of all field points are below 6.5 nm. It can meet the requirement of deep ultraviolet immersion lithographic experiment with 45 nm nodes.