多参数联合优化是光刻分辨率增强技术的发展方向。提出了一种以光刻胶三维形貌差异为评价目标的光刻多参数联合优化方法。以多个深度位置的光刻胶图形误差为目标函数,对光源、掩模、投影物镜波前、离焦量和曝光剂量进行联合优化,提高了光刻胶图形三维形貌的质量。为获得较高的优化效率,采用自适应差分进化算法实现光源和掩模的优化,并针对其他参数的特点,采用不同优化方法进行优化。对密集线、含有交叉门的复杂掩模图形和静态随机存储器中的典型图形进行了仿真验证,可用焦深的最大值分别达到237 nm、115 nm 和144.8 nm,曝光宽容度的最大值分别达到18.5%、12.4%和16.4%。与基于空间像的光源掩模投影物镜联合优化技术相比,所提方法明显扩大了工艺窗口。

Multi-parameter joint optimization is a trend in lithography resolution enhancement techniques. A multi-parameter joint optimization method for lithography based on the 3D topography difference of photoresist was proposed herein. By using the error of photoresist pattern at multiple depth positions as an objective function, the light source, the mask, the wavefront of the projection objective lens, the defocusing amount, and the exposure dose were jointly optimized, which improved the quality of the 3D topography of photoresist pattern. To obtain higher optimization efficiency, the adaptive differential evolution algorithm was adopted to optimize the light source and the mask, and different optimization methods were employed based on the characteristics of other parameters. The simulation results of dense lines, complex mask patterns with cross gate structure, and typical patterns in the static random access memory show that the maximum possible focal depth is 237 nm, 115 nm, and 144.8 nm, and the maximum exposure latitude is 18.5%, 12.4%, and 16.4%, respectively. Compared with the joint optimization technology of light source mask projection objective lens based on aerial image, the proposed method provides much larger process window.