Gong Shuang, Yang Baoxi, Huang Huijie
Appl Opt. 2022 Apr 1;61(10):2706-2714. doi: 10.1364/AO.449787.
Illumination-integrated nonuniformity (IINU) is a key factor in determining resolution and critical dimension uniformity, which are important performance parameters in advanced lithography systems. To further reduce the IINU, a uniformity correction technology was adopted. In this paper, a low-cost and simple-structure approach for uniformity correction with higher flexibility and better correction capability is proposed. The method is composed of two dynamic gray filters with a specific transmittance distribution, which can form different correction curves by controlling the displacement of the gray filters. The frequency limitation of the defocus uniformity correction system is analyzed. A uniformity correction system design method based on the particle swarm optimization algorithm is introduced. Based on the proposed method, a dynamic gray filter uniformity correction system is applied to an illumination optical system. The experimental results show that the value of the corrected IINU reaches less than 0.7%, which satisfies the IINU requirements of advanced lithography systems. This verifies the higher flexibility and better correction capability of the proposed method.
照明集成非均匀性（IINU）是决定分辨率和关键尺寸均匀性的关键因素，而分辨率和关键尺寸均匀性是先进光刻系统中的重要性能参数。为了进一步降低IINU，采用了一种均匀性校正技术。本文提出了一种低成本、结构简单、具有更高灵活性和更好校正能力的均匀性校正方法。该方法由两个具有特定透过率分布的动态灰度滤波器组成，通过控制灰度滤波器的位移可以形成不同的校正曲线。分析了离焦均匀性校正系统的频率限制。介绍了一种基于粒子群优化算法的均匀性校正系统设计方法。基于所提出的方法，将动态灰度滤波器均匀性校正系统应用于照明光学系统。实验结果表明，校正后的IINU值小于0.7%，满足先进光刻系统的IINU要求。这验证了所提方法具有更高的灵活性和更好的校正能力。
