高NA光刻机投影物镜偏振像差检测技术研究
文献类型：学位论文
| 作者 | 沈丽娜 |
| 学位类别 | 博士 |
| 答辩日期 | 2016 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 王向朝 |
| 关键词 | 光刻机 矢量成像模型 偏振像差 泡利-泽尼克系数 偏振像差检测 |
| 其他题名 | Study on polarization aberration measurement techniques for the projection lens of high-NA lithography tools |
| 中文摘要 | 光刻机是集成电路制造的核心设备，投影物镜系统是光刻机中最复杂、最昂贵的分系统之一。投影物镜偏振像差会引起图形位置偏移、最佳焦面偏移和焦深减小，从而降低光刻成像质量，影响光刻机的分辨率、套刻精度、CDU（Critical Dimension Uniformity）等重要性能指标。高NA（Numerical Aperture）光刻成像中，偏振像差的这些不利影响愈加突出，不容忽视。高分辨率光刻迫切要求对偏振像差进行快速、高精度的测量和控制。现有的偏振像差检测技术需要特制的测试掩模或偏振态测量装置，系统结构和计算过程相对复杂。为了简化偏振像差检测系统结构，实现偏振像差的快速精确测量，本文研究了高NA光刻机投影物镜偏振像差检测技术，主要内容包括以下几个方面： 1. 研究了偏振像差对光刻成像的影响。基于矢量部分相干成像模型，在 级衍射光干涉条件下，推导了泡利-泽尼克系数与交替相移掩模（Alt-PSM）空间像的成像位置偏移（IPE）和最佳焦面偏移（BFS）之间的线性关系表达式。对该线性关系进行了仿真实验验证。各IPE/BFS仿真值与泡利-泽尼克系数间的线性相关系数绝对值最小达到0.987，表明了所得解析结果的正确性。在此基础上，建立了空间像偏移量（IPE和BFS）与偏振像差之间的两光瞳和四光瞳线性关系模型，为研究偏振像差检测技术提供了理论依据。 2. 研究了照明偏振角对偏振像差灵敏度（PAS）的影响。基于矢量部分相干成像模型，在 级衍射光干涉条件下，推导了Alt-PSM空间像偏移量（IPE和BFS）的PAS与照明偏振角之间的关系表达式以及PAS的零值点和极值点条件表达式。对所得解析结果进行了仿真实验验证。以30°偏振角为例，比较了PAS的解析与仿真结果，其差异都在10-2数量级，表明了两种结果具有很好的一致性。此外，根据解析式获得的PAS零值点和极值点均与仿真结果匹配。解析结果为本文偏振像差检测技术研究中最佳照明偏振态的选择提供了理论依据。 3. 提出了一种光刻机投影物镜偏振像差原位检测方法。结合X和Y线性偏振照明条件下标定的偏振像差灵敏度系数，消除了灵敏度矩阵列向量间的线性相关性。利用不同数值孔径和部分相干因子条件下Alt-PSM空间像的偏移量（IPE和BFS），计算得到了泡利光瞳Pa0_Ph和Pa1_Im中低阶像差的泡利-泽尼克系数。仿真实验结果表明奇像差（彗差和三波差）的检测精度优于1.60mλ，球差的检测精度优于0.97mλ，像散的检测精度优于3.07mλ。该方法简化了偏振像差检测系统结构和计算过程，可用于低阶泡利-泽尼克偏振像差的快速精确测量。 |
| 英文摘要 | Lithography tools are the key equipments for the integrated circuit manufacturing. The projection lens is one of the most complex and expensive subsystems of the lithography tools. The polarization aberration of projection lens can cause image placement error (IPE), best focus shift (BFS), the DOF (depth of focus) decrease and so on. It consequently leads to the degradation of lithographic image quality and affects the performance of lithoragphy tools, such as the resolution, overlay error, critical dimension uniformity and so on. In high-NA lithographic imaging, the undesirable impact of polarization aberration becomes increasingly obvious and non-ignorable. High-resolution lithography has an urge to explore fast and accurate polarization aberration measurement and control techniques. The special masks or polarization measuring instruments are required in the existing polarization aberration measurement techniques, thus the system construction and calculation process are relatively complex. In this dissertation, the polarization aberration measurement techniques for the projection lens of high-NA lithography tools are studied. The main contents are as follows: 1. The impact of the polarization aberration on the lithographic imaging is studied. Based on the vector partially coherent imaging model, the expressions of the linear relationships between the IPE/BFS and Pauli-Zernike coefficients are derived from the aerial image of alternating phase-shift mask (Alt-PSM) formed by the interference of 1st-order diffracted lights. Simulations are performed to verify the derived relational expressions. The absolute values of linear correlation coefficients between the simulated IPE/BFS and the Pauli-Zernike coefficients fall in the range of [0.987,1]. This indicates the validity of the derived analytical expressions. On this basis, the linear ralationship models between aerial image offsets and polarization aberration for two pupils and four pupils are established. These models provide a theoretical basis for exploring new polarization aberration measurement techniques. 2. The impact of the polarization angles of illumination on the polarization aberration sensitivities (PAS) is studied. Based on the vector partially coherent imaging model, the relational expressions of the PAS and the polarization angles of illumination are derived from the aerial image of Alt-PSM formed by the interference of 1st-order diffracted lights. Then the expressions for the zero-value points and the extremum points of PAS are derived. Simulations are performed to verify the derived analytical expressions. Take the polarization angle of 30° as an example, the PAS calculated from the analytical expressions are compared with the simulated PAS, and the differences between them are on the level of 10-2. This result illustrates well their consistency. Moreover, the zero-value points and extremum points, obtained from the analytical expressions, match well with the simulation results. The derived analytical expressions provide guidance for choosing the optimal polarization of the illumination in exploring new polarization aberration measurement techniques. 3. A polarization aberration measurement method for the lithographic projection lens is proposed. The linear dependence of the column vectors of the sensitivity matrix is eliminated by combining the polarization aberration sensitivity coefficients calibrated under X and Y linearly polarized illumination. The Pauli-Zernike coefficients of the low-order aberrations in Pauli pupils Pa0_Ph and Pa1_Im are retrieved using the IPE and BFS of the Alt-PSM’s aerial images obtained under multiple parameters (NA and σ) conditions. The simulation results show that the measurement accuracy of odd aberrations (coma and three-leaf clover), spherical aberration and astigmatism aberration are better than 1.60mλ, 0.97mλ and 3.07mλ, respectively. The proposed method simplifies the system construction and calculation process, and can measure fastly and accurately the low-order Pauli-Zernike polarization aberrations. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15977]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 沈丽娜. 高NA光刻机投影物镜偏振像差检测技术研究[D]. 中国科学院上海光学精密机械研究所. 2016. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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