浸没式光刻机投影物镜波像差检测技术研究
文献类型：学位论文
| 作者 | 诸波尔 |
| 文献子类 | 博士 |
| 导师 | 王向朝 |
| 关键词 | 浸没式光刻机 Immersion lithography tool 投影物镜 Projection lens 波像差检测 Wavefront aberration measurement 空间像 Aerial image 主成分分析 Principal component analysis (PCA) |
| 其他题名 | Study on Wavefront Aberration Measurement for Immersion Lithographic Projection Lens |
| 英文摘要 | 集成电路产业是信息技术产业的核心，是支撑经济社会发展和保障国家安全的战略性、基础性和先导性产业。光刻机是集成电路制造的核心装备，投影物镜系统是光刻机的关键分系统之一。投影物镜的波像差影响光刻成像对比度，缩小工艺窗口，降低集成电路产品良率。当前，最先进浸没式光刻机的投影物镜波像差已经达到了亚纳米量级。随着光源掩模优化等分辨率增强技术的应用和准分子激光功率的不断提高，投影物镜热效应引起的波像差动态变化对光刻成像造成严重影响。为保证高质量成像，需要对波像差进行原位检测与控制。目前，基于瞳面测量的波像差检测技术是国际上的主流技术，具有检测速度快、精度高的优点，但需要额外的硬件成本。本课题组已提出基于空间像主成分分析的光刻机投影物镜波像差检测技术(AMAI-PCA)，具有成本低、检测速度快、精度高、可以原位检测波像差的优点，为干式光刻机投影物镜波像差检测提供了一种新的技术手段。但由于已有检测模型的限制，尚不能应用于浸没式光刻机投影物镜波像差的检测。本文基于矢量光刻成像理论建立高灵敏度检测模型，提出了浸没式光刻机投影物镜波像差检测技术，大幅度提高了检测精度，扩展了可测泽尼克系数范围，在此基础上，显著提高了波像差求解速度。主要内容包括： 1. 本文提出了一种光刻机投影物镜热效应快速仿真模型。通过光瞳面光强映射简化了光强计算过程，并推导镜片温度分布的简化公式加快了温度计算过程，实现了光刻机曝光过程中投影物镜热效应对波像差影响的快速(~10 min)、精确仿真。商用前道扫描光刻机热效应实验结果表明，本模型的仿真精度(Rs2)优于0.99。本模型用于分析光刻机投影物镜热效应对波像差的影响，对于高灵敏度波像差检测模型的建立具有指导作用。 2. 本文提出了一种基于矢量光刻成像模型的高精度波像差检测技术。通过采用偏振光照明和矢量光刻成像模型，准确表征了浸没式光刻机的空间像，建立了空间像光强分布与泽尼克系数之间的线性模型，提高了投影物镜波像差的检测精度。光刻仿真软件PROLITH 的仿真结果表明，本技术对33 项泽尼克系数(Z5~Z37)的检测精度优于0.85mλ (0.1636 nm)。 3. 本文设计了一种八方向孤立空测量标记，提出了基于该测量标记和旋转矩阵法的高阶波像差检测技术。本技术采用八方向孤立空测量标记实现了对投影物镜光瞳面波前的高效率采样，并采用旋转矩阵法提高了建模速度，从而建立了对投影物镜高阶波像差更加敏感的检测模型，将可测泽尼克像差项数由33 项扩展至60 项。PROLITH 仿真结果表明，本技术对60 项泽尼克系数(Z5~Z64)的检测精度优于1.03mλ (0.1980 nm)。 4. 本文提出了一种基于多偏振照明模式的波像差快速求解方法。通过采用线性采样方式，并结合不同偏振照明模式下的空间像进行建模，有效降低了采样数，加快了建模过程，提高了波像差求解模型的灵敏度。PROLITH 仿真结果表明，本方法对60 项泽尼克系数(Z5~Z64)的求解精度优于1.06mλ (0.2037 nm)。相比于基于八方向孤立空标记的高阶波像差检测技术，本方法在不损失求解精度的前提下，求解速度提高了5 倍以上。相比于AMAI-PCA 技术，本方法的波像差求解速度提高了3 倍以上。; Integrated circuit industry is the core of the information technology industry. It is also a strategic, fundamental and guiding industry for the development of national economy and society. Lithography tools are the most critical equipment in the manufacturing process of very-large-scale integrated circuits. Projection lens is one of the most important subsystems of a lithography tool. The wavefront aberration of a projection lens will deteriorate the lithographic imaging performance, shrink the process window, and depress the yield of chips. Nowadays, the wavefront aberration of advanced immersion lithographic projection lens is less than 1 nm. Owing to the increasement of the laser power and application of resolution enhancement techniques (RETs) such as source mask optimization (SMO), the lens heating effect leads to serious variation of the wavefront aberration that degrades the imaging performance gravely. In order to guarantee high imaging quality, the wavefront aberration needs to be in-situ measured and controlled. At present, the aberration measurement technique based on pupil measurement is the primary method to measure the aberration of an immersion lithographic projection lens. It measures the wavefront aberration fast and accurately. However, it requires extra cost. Our group has proposed an aberration measurement technique based on principal component analysis of aerial image (AMAI-PCA). It has the advantages of being fast, accurate, and low cost. This technique provides an optional method for the aberration measurement of a dry lithographic projection lens. Limited by the measurement model, conventional AMAI-PCA is not capable of measuring the aberration of an immersion lithographic projection lens. In this dissertation, the measurement model with high sensitivity is built based on vector imaging theory, then wavefront aberration measurement techniques based on principal component analysis of aerial image for an immersion lithographic projection lens are proposed. The measurement accuracy is improved, the measuring range is extended. The retrieving speed is also increased. The main contents are as follows: 1. A novel fast thermal effect model (FTM) for a lithographic projection lens is proposed. The intensity calculation is simplified using pupil intensity mapping. Simplified temperature calculation formula is derived to accelerate the calculation process. As a result, the impact of thermal effect on the wavefront aberration is simulated fast (~10 min) and accurately. Comparison between the simulation and experiment performed on a lithography tool shows that the accuracy (R-Square) of FTM is better than 0.99. The model is used to analyze the impact of thermal effect on the wavefront aberration, which benefits building the wavefront aberration measurement model with high sensitivity. 2. A wavefront aberration measurement technique for an immersion lithographic projection lens based on vector imaging model is proposed. Aerial image of an immersion projection lens is modeled accurately by using polarized light and vector imaging model, as well as considering the polarization properties. A linear relationship model between the aerial image intensity distribution and the Zernike coefficients is built. As a result, the measurement accuracy of wavefront aberration is improved. Simulations using the commercial lithography simulator PROLITH show that the proposed technique can retrieve 33 terms of Zernike coefficients (Z5~Z37) with measurement accuracy better than 0.85mλ (0.1636 nm). 3. A binary target with eight directions is designed. Subsequently a high-order wavefront aberration measurement technique based on the target and rotated regression matrix is proposed. The target improves the efficiency of pupil sampling, while the rotated regression matrix improves the model building speed. The measurement model which is sensitive to high-order wavefront aberration is built. As a result, the measuring range of Zernike coefficient is extended to 60 terms from 33 terms, and the measurement accuracy of high-order wavefront aberration is improved. Simulations using PROLITH show that the proposed technique retrieves 60 terms of Zernike coefficients (Z5~Z64) with accuracy better than 1.03mλ (0.1980 nm). 4. A fast and accurate high-order wavefront aberration retrieving method using multi-polarized illuminations is proposed. Zernike coefficient group is set by linear sampling, and aerial images are simulated under different polarized illuminations. The wavefront aberration retrieving model is built using the aerial images. The proposed method effectively reduces the number of aerial images. The modeling is accelerated and the sampling efficiency is improved. Meanwhile, the proposed method is sensitive to high-order wavefront aberration. Simulations using PROLITH show that the proposed method retrieves 60 terms of Zernike coefficients (Z5~Z64) with retrieving accuracy better than 1.06mλ (0.2037 nm). The method is compared with that based on a binary target with eight directions. The retrieving speed is increased by more than 5 times while the retrieving accuracy is almost the same. Compared with AMAI-PCA, the retrieving speed of the method is increased by more than 3 times. |
| 学科主题 | 光学工程 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31138]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 诸波尔. 浸没式光刻机投影物镜波像差检测技术研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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