193nm光刻投影物镜单镜支撑仿真分析及实验研究

光刻是大规模集成电路制造过程中最为关键的工艺,光刻的分辨力主要取决于光刻投影物镜的光学性能。光刻投影物镜光学元件面形精度为纳米量级,其对光学元件的加工及物镜单镜支撑提出了极高的要求。为193nm光刻投影物镜高精度的单镜面形,设计了一种运动学单镜支撑结构。运用有限元法(FEM)分析光刻投影物镜单镜运动学支撑结构在重力下物镜镜片的面形变化量,经分析物镜镜片的峰值(PV)值为15.46nm,均方根(RMS)误差为3.62nm。为了验证有限元计算精度,建立了可去除参考面面形及被测面原始面形的方法。经过分析对比,仿真结果与实验结果面形的PV值为2.356nm,RMS误差为0.357nm。研究结果表明,所设计的基于运动学193nm光刻投影物镜单镜支撑结构能够满足193nm光刻投影物镜系统对于物镜机械支撑结构的要求。

Simulation and Experimental Research of 193 nm Projection Lithography Lens Supporting

Lithography is the most important technology when manufacturing of large scale integrated circuit. Since the resolution of a lithographic tool is determined by the performance of the imaging optics. The surface accuracy of lithographic projection objectives is on nanometer scale. It is obvious that the fabrication of such high-quality optics and single lens supporting requires tremendous efforts. In order to design the structure of single lens supporting with high-precision, the surface form of single lens is studied, under gravitational condition. Then, the support structure is analyzed in detail by finite element method (FEM) and a new type of flexible support is presented. Analytical results indicate that the surface figure accuracy of the mirror reach peak valley (PV) of 15.4 nm and root mean square (RMS) of 3.62 nm under the load case of gravity. In order to accept high accuracy for optical surface form analyses by FEM, a new method which could remove the surface form of reference surface and the original surface form of tested surface is built. According to the method, the differences of PV magnitudes and RMS values are only 2.356 nm and 0.357 nm, respectively. The results show that the proposed kinematics mount structures satisfy the mechanical requirements of mounts for 193 nm projection lithographic lens.