支撑变形对亚纳米级面形检测精度的影响

Influence of Support Deformation on Sub-Nano Level Surface Shape Detection Accuracy

摘要:

光刻投影物镜中透物镜的面形精度是影响光学系统成像质量的关键因素之一,而支撑变形是影响面形精度的一个非常重要的因素。为提高大口径透镜的光学检测复现性,设计了一种整体式柔性支撑结构,分析了重力作用下弹片数量和各尺寸参数等对透镜面形精度及复现精度的影响。分析结果表明:增加弹片数量、减小支撑距离透镜中心的距离及增大弹片厚度可使透镜的变形减小；可以通过缩短弹片长度、增加弹片厚度及弹片数量来提高复现精度。根据各影响因素与复现性的关系分析得到的优化参数下的复现精度为0.21nm rms,能够满足深紫外光刻投影物镜中透镜的高精度面形要求。

Abstract:

The surface shape accuracy of the transparent objective lens in the lithographic projection objective is one of the key factors affecting the imaging quality of the optical system, and the support deformation is a very important factor affecting the surface shape accuracy. In order to improve the reproducibility of the optical inspection of the large-aperture lens, an integral flexible support structure was designed, and the influence of the number of shrapnel and various dimensional parameters on the surface accuracy and reproducibility of the lens under the action of gravity was analyzed. The analysis results show that:increasing the number of shrapnel, reducing the distance between the support and the center of the lens and increasing the thickness of the shrapnel can reduce the deformation of the lens. The reproduction accuracy can be improved by shortening the length of the shrapnel, increasing the thickness of the shrapnel and the number of shrapnel. According to the analysis of the relationship between the influence factors and the reproducibility, the reproducibility under the optimized parameters is 0.21nm rms, which can meet the high-precision surface shape requirements of the lens in the deep ultraviolet lithography projection objective.