针对光刻机照明系统的实际应用需求,提出了一种光瞳特性参数的评估算法。该算法通过对光瞳强度分布进行转换,可以在不同照明模式下同时计算光瞳椭圆度、X方向光瞳极平衡性、Y方向光瞳极平衡性和四象限光瞳极平衡性等多种光瞳特性参数。以一种28 nm节点扫描光刻机照明系统的中继镜组为实例,对其在传统照明模式下进行光瞳特性参数计算分析。仿真结果显示,全视场光瞳椭圆度最大值为0.95%,X方向和Y方向光瞳极平衡性最大值分别为0.18%和0.19%,四象限光瞳极平衡性最大值为0.66%,均满足28 nm节点扫描光刻机实际指标需求。所提算法在光学设计阶段能快速评估光瞳性能。

An evaluation algorithm of the pupil characteristic parameters is proposed, aiming at the practical application requirements of lithography illumination system. By changing the intensity distribution of pupil, this algorithm can be used to simultaneously calculate the pupil ellipticity, non-balance_X, non-balance_Y, non-balance_quad, and other pupil characteristic parameters in different illumination modes. The relay lens set of the 28 nm node scanning lithography illumination system is used as an example and the pupil characteristic parameters under the traditional illumination mode are analyzed. The simulation results show that the maximum value of pupil ellipticity in the full field of view is 0.95%, and the maximum values of non-balance_X and non-balance_Y are 0.18% and 0.19%, respectively. In addition, the maximum value of non-balance_quad is 0.66%. These data satisfy the actual index requirements of the 28 nm node scanning lithography. The proposed algorithm can help to evaluate the pupil performances quickly at the optical design stage.