全视场低偏振像差敏感度矢量成像分辨率增强及优化方法

Resolution enhancement technique (RET) is a method and technology to continuously break through the Rayleigh diffraction resolution limitation by manipulating the light’s direction, amplitude, phase and polarization. RET is still key technology for 22-7nm IC lithography. However polarization aberration (PA) impact on RET and image performance. Vectorial RET with low PA sensitivity in full field of image should be studied emergently because PAs exist in immersion lithography system which impact on image resolution，fidelity and depth of focus. Otherwise，lithography cannot meet the requirements of 22-7nm node IC fabrication. PAs represented by eight Jones pupils are very complicated, which result in a difficulty of inverse image theory. So that RET accounting PA has not been developed yet. It is difficult to study the influence of polarization aberration on image performance by forward image theory. However it is daunting complexity if inverse image taking PA into account. Vectorial RET to achieve lower polarization aberration sensitivity in full field of image adds much complexity. No one has been touched it. Study on the novel method of vectorial RET to achieve low polarization aberration sensitivity in full field is urgently. Based on vectorial imaging theory and RET established by us, we first evaluate the PA sensitivity systemically, Then develop the statistical method to characterization of random polarization aberration in full field. Finally we deeply investigate the inverse vectorial imaging and RET method to achieve low PA sensitivity of the RET in full field of image. And demonstrate the effective of the method by simulation to realize lithography imaging in greater depth of focus, higher resolution and fidelity.

光刻分辨率增强技术（RET）以光传播与成像理论为基础，调控光波的方向、振幅、相位和偏振，不断突破瑞利衍射分辨极限。矢量RET依然是22-7nm技术节点的集成电路关键技术。但是，浸没光刻系统的偏振像差影响RET及成像分辨率、保真度和焦深。 因此迫切需要全视场低误差敏感度的矢量RET新方法。 否则，难实现22-7nm IC光刻。用8个琼斯光瞳表示的偏振像差比标量波像差复杂，研究正向成像中偏振像差成像影响并不难，含偏振像差的逆向成像理论模型和矢量RET变得非常复杂，进一步导致全视场低偏振像差敏感度的矢量RET方法的研究令人望而却步，无人触及。本项目研究系统含偏振像差矢量成像及RET对偏振像差的敏感度，深入研究全视场随机偏振像差的统计理论和表征方法，建立全视场低偏振像差敏感度的矢量RET及多目标优化方法，实现在更大焦深内、更高分辨率和保真度光刻成像。

22-14nm及以下技术节点IC光刻技术必须采纳光源-掩模联合优化（SMO）分辨率增强技术（RET）。因光刻曝光系统是非零像差系统（存在厚掩模效应和物镜偏振像差―用琼斯光瞳表征），采用常规（零像差）SMO理论和方法，在IC制造中，需要较长时间的工艺迭代优化。.本项目研究建立了含偏振像差的严格矢量成像模型、以及低像差（含波像差和偏振像差）敏感度SMO分辨率增强理论及方法，并实现了厚掩模偏振像差（含标量像差）的精确表征，为后续工作奠定了基础。突破了含偏振像差的矢量SMO分辨率增强理论，建立了全视场矢量SMO及成像性能对偏振像差敏感度的评估方法。.研究了投影物镜及厚掩模效应的像差对各视场点SMO及光刻成像性能的影响；研究了全视场、多目标、低像差敏感度SMO分辨率增强理论模型及多目标优化算法（MOSMO）；创新性建立了低像差敏感度、平均权重和自适应权重的SMO优化方法（Mean- MOSMO和Adaptive-MOSMO）。.构建了空间像的强度与琼斯光瞳的解析关系，建立了偏振像差及检测理论与方法；全视场低像差敏感度SMO基础上，进一步构建建立光瞳补偿常规（零像差）SMO不能补偿的随机像差对光刻成像的影响，并建立了全视场多个琼斯光瞳约束的SMPWO分辨率增强理论和方法（MPWO）。.创新建立了低误差敏感度、多参数协同优化分辨率增强方法，增加了光源参数、掩模参数、投影物镜NA、光刻机前后烘时间、光刻机显影时间及其他工艺参数等6个优化自由度，进一步提高成像分辨率、保真度和工艺窗口。开发了全视场低像差敏感度矢量RET及多目标优化方法的系列软件包。.上述创新型研究理论、方法和技术，是我国高端光刻机研制和高端IC制造工艺研发面临的众多卡脖子技术的一部分，其成果应用，将极大缩短光刻机和工艺的研发周期，提高光刻成像质量、成品率和集成电路的产率。