光学学报, 2013, 33 (1): 0111003, 网络出版: 2012-12-14
基于空间像自适应降噪的投影物镜波像差检测方法
Projection Lens Wave-Front Aberration Measurement Method Based on Adaptive Aerial Image Denoising
成像系统 光刻机 波像差检测 加权最小二乘法 空间像 降噪 imaging systems microlithographic system wave-front aberration measurement weighted least square aerial image denoising
摘要
提出了一种基于空间像自适应降噪的投影物镜波像差检测方法。通过对空间像进行统计分析,获取空间像的噪声模型和噪声标准差模型。以噪声标准差为权重因子,利用加权最小二乘法对空间像进行主成分分解,可以实现对空间像的自适应、无损降噪,从而得到更为精确的主成分系数和泽尼克系数。使用光刻仿真软件PROLITH的仿真结果表明,在相同的噪声水平下,0.1λ像差幅值内,与基于空间像主成分分析的波像差检测技术相比,精度提高30%以上。在使用光刻实验平台测量Z8调整量的实验中,该方法的精度更高。
Abstract
A wave-front aberration measurement method of lithographic projection lens based on adaptive aerial image denoising is proposed. Principal component analysis (PCA) and multivariate linear regression analysis are used for model generation. Weighted least-square (WLSQ) method based PCA is used to get the principal component coefficients that are used for extracting the actual Zernike coefficients. Both the noise model of aerial images and the standard deviation model of noises are obtained by statistical analysis of actually measured aerial images. The standard deviation of the noise is used as weighting factors of the weighted least-square method. Accurate principal component coefficients and Zernike coefficients can be calculated because of the adaptive and lossless denoising ability of this method. Compared with wave-front aberration measurement techniques based on principal component analysis of aerial images (AMAI-PCA), the new method can provide more accurate results. Simulations show that AMAI-WLSQ can enhance the accuracy by more than 30% when the range of wavefront aberration is within 0.1λ. Experiments also show that AMAI-WLSQ can detect aberration shifts more accurately.
杨济硕, 李思坤, 王向朝, 闫观勇, 徐东波. 基于空间像自适应降噪的投影物镜波像差检测方法[J]. 光学学报, 2013, 33(1): 0111003. Yang Jishuo, Li Sikun, Wang Xiangzhao, Yan Guanyong, Xu Dongbo. Projection Lens Wave-Front Aberration Measurement Method Based on Adaptive Aerial Image Denoising[J]. Acta Optica Sinica, 2013, 33(1): 0111003.