光源形状及掩模结构对极紫外光刻成像性能影响的基础研究

The extreme ultraviolent(EUV) lithography combined with source and mask optimization(SMO) techniques is a leading solution for patterning at the node of 10nm and below. There are three major problems in the state-of-art SMO techniques. Firstly, the impacts of the characteristics of EUV lithography system on the imaging qualities are barely considered. Secondly, the corresponding cost function is not wholesome. Thirdly, more parameters should be involved in the optimization. To solve the problems, basic research of SMO in EUV lithography is implemented, which includes modeling of shadowing effect and flare in EUV lithography, development of new cost function with pattern shift and critical dimension uniformity considered, study of new optimization method with optimize parameters of source, mask pattern and absorber thickness. Based on current SMO methods, this project innovatively co-optimizes the source and mask three dimension (M3D) structure which consists of mask pattern and absorber thickness in EUV lithography. The impacts of M3D to the imaging of EUV lithography is systematically analyzed and elucidated. The optimized source and mask are compared to the results from conventional SMO with emphasis on the improvement of process window and complicacy of the mask pattern. This study further reveals the intrinsic features and rules of absorber thickness to the imaging properties. This study also significantly provides a novel method for source and mask optimization and relative analysis as well as a new direction for resolution enhancement technology.

极紫外（EUV）光刻结合光源掩模优化(SMO)是实现10nm及以下节点成像的主要技术手段。目前EUV下的SMO方法存在以下问题：未充分考虑光刻系统的特性；评价函数不健全；优化方法中自由度较少。针对以上问题，本项目对EUV下的SMO方法进行基础性科学研究。主要内容有：对EUV光刻的阴影和杂散光效应进行数学建模；建立包含图形偏移、特征尺寸均匀性的新型评价函数；建立包含光源、掩模图形、掩模吸收层厚度等更高自由度的优化算法。本项目旨在通过对现有EUV下的SMO方法进行创新性研究，实现EUV下光源、掩模图形、吸收层厚度联合优化的目标。本研究系统分析掩模三维结构对EUV光刻成像性能的影响规律，以及新方法结果相对于传统优化方法结果在工艺窗口、掩模复杂度等方面的优势。本项目研究将进一步揭示成像性能指标随吸收层厚度变化的相应特征及规律，提出SMO的新方法，为光刻分辨率增强技术发展提供新的指导方向。

极紫外光刻结合光源掩模联合优化 (SMO)是解决10nm及以下节点光刻成像的主要技术手段之一。以极紫外光刻的光源以及包含掩模图形、吸收层厚度在内的掩模三维结构联合优化方法为研究对象，通过对阴影效应、杂散光效应进行数学建模，将图形偏移、特征尺寸均匀性引入评价函数中，将光源、掩模图形、掩模吸收层厚度作为优化自由度，建立新的优化方法及相应的仿真平台。针对EUV光刻及SMO方法存在的线条边缘粗糙度评估、焦平面精确量测、衬底表面不平整性等问题，进行研究并提出相应的研究成果及解决方法。