为保证投影光刻物镜的成像性能并降低制造成本, 提出了一种更全面可靠的公差分析方法。该方法在以波像差均方根(RMS)值作为评价标准的传统分析方法基础上, 添加波像差峰谷(P-V)值作为评价指标, 并据此选择合理的补偿器组合。在系统波像差的RMS值和P-V值均满足要求的情况下, 采用了较少的补偿器, 从而有效地降低了系统的制造难度和成本。结合实验室设计的一套90nm投影光刻物镜进行了公差分析和补偿器优选。结果表明, 利用该方法选择的7个补偿器, 使得系统在97.7%置信区间内, 全视场波像差的RMS值≤0.0412 λ, P-V值≤0.2469 λ, 满足了90nm投影光刻物镜的像质要求。

A simple and reliable method of tolerance analysis is proposed to ensure the performance of lithographic projection lens and minimize the manufacturing costs of lithographic projection lens. This method defines P-V wavefront error as merit function based on RMS wavefront error, and selects the optimal compensators. Compared to present methods, this method decreases mechanical complexity and minimizes the manufacturing costs by adopting less compensators, with both RMS wavefront error and P-V wavefront error achieving the requirement. As an example the method is applied to a refractive projection lens for 90nm resolution lithography projection lens designed by us. The results show that, only with 7 compensators, RMS wavefront error and P-V wavefront error at 97.7% probability are less than 0.0412 λ and 0.2469 λ, respectively. In conclusion, this method is able to meet the performance requirement of lithographic projection lens.