大焦深数字灰度光刻物镜设计

为了提高数字灰度光刻系统的焦深,研究了基于点扩散函数稳定性的光瞳编码优化方法,在此基础上综合考虑系统的成像对比度和分辨率,利用工程计算软件MAPLE和光学设计软件ZEMAX设计了一种分辨率为1m的含有5区相位型光瞳滤波器的长焦深数字灰度光刻系统。结果表明,系统调制传递函数表现出离焦不变性,在保证像方分辨率的前提下,系统的焦深被延拓到原有焦深的2.5倍以上,且在整个焦深空间内系统性能与焦点处保持一致,从而提高了光刻系统的工艺容限。所得实验结果与理论分析一致,说明了设计的可行性。

Design of objective lens with long focus depth for digital grayscale lithography

In order to improve focus depth of digital grayscale lithography, an optimization method of pupil coding was studied based on the stabilization of point spread function. A digital grayscale lithography system with 1m resolution, long focus depth and five-zone phase pupil filter was designed by using MAPLE and ZEMAX software. The results show that system modulation transfer function has defocus invariance. Under the premise of image resolution stability, the focus depth of the system is extended 2.5 times more than the original focus depth. And then, the system performance within the space of the entire focus depth is consistent with the system performance at the focal point. Thereby, the tolerance of lithography system is increased. The experimental result is the same as the theoretical analysis and the design is feasible.