Optical lithography is a critical technique to fabricate nano-scale semiconductor devices by replicating the layouts of integrated circuits from the lithography mask onto the silicon wafer. As the critical dimension of integrated circuits continuously shrinks, source and mask optimization (SMO) methods are extensively used to improve the resolution and image fidelity of lithography patterning. However, the theoretical lower bound of the lithography pattern error in the SMO framework is not yet understood. This paper introduces an informational lithography approach to unveil the information transmission mechanism in lithography systems under freeform illumination configurations. The lithography system is regarded as an information channel, where the mask pattern and the print image on the wafer are modeled as the statistical input and output signals, respectively. Subsequently, we derive the optimal information transfer (OIT) of the lithography system, which represents the best information transfer strategy rendering the least image distortion. Based on the OIT, we derive a lower bound for the lithography pattern error, and the corresponding optimal source pattern and optimal mask probability distribution. Finally, we propose a new SMO algorithm based on the information theoretical framework to effectively improve the lithography image fidelity compared to the existing gradient-based SMO algorithm.

中文翻译：

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基于源和掩模优化的信息光刻方法

光刻是通过将集成电路的布局从光刻掩模复制到硅晶片上来制造纳米级半导体器件的关键技术。随着集成电路的关键尺寸不断缩小，源和掩模优化 (SMO) 方法被广泛用于提高光刻图案的分辨率和图像保真度。然而，SMO 框架中光刻图案误差的理论下限尚不清楚。本文介绍了一种信息光刻方法，以揭示自由曲面照明配置下光刻系统中的信息传输机制。光刻系统被视为一个信息通道，其中晶圆上的掩模图案和印刷图像分别建模为统计输入和输出信号。随后，我们推导出光刻系统的最佳信息传输（OIT），它代表了呈现最少图像失真的最佳信息传输策略。基于 OIT，我们推导出光刻图案误差的下限，以及相应的最佳源图案和最佳掩模概率分布。最后，我们提出了一种基于信息理论框架的新 SMO 算法，与现有的基于梯度的 SMO 算法相比，有效提高了光刻图像的保真度。这代表了呈现最少图像失真的最佳信息传输策略。基于 OIT，我们推导出光刻图案误差的下限，以及相应的最佳源图案和最佳掩模概率分布。最后，我们提出了一种基于信息理论框架的新 SMO 算法，与现有的基于梯度的 SMO 算法相比，有效提高了光刻图像的保真度。这代表了呈现最少图像失真的最佳信息传输策略。基于 OIT，我们推导出光刻图案误差的下限，以及相应的最佳源图案和最佳掩模概率分布。最后，我们提出了一种基于信息理论框架的新 SMO 算法，与现有的基于梯度的 SMO 算法相比，有效提高了光刻图像的保真度。