大数值孔径下的偏振成像分析.doc

光电工程Opto-Electronic Engineering第 38 卷第 12 期2011 年 12 月Vol.38, 光电工程 Opto-Electronic Engineering 第 38 卷第 12 期 2011 年 12 月 Vol.38, No.12 Dec, 2011 文章编号：1003-501X(2011)12-0035-06 大数值孔径下的偏振成像分析 勇 1,2，邢廷文 1，杨 雄 1 刘 ( 1. 中国科学院光电技术研究所，成都 610209； 2. 中国科学院研究生院，北京 100049 ) 摘要：光刻设备的分辨率越来越高，以满足集成电路特征尺寸不断缩小的要求。根据瑞利判据，可以通过缩小曝 光波长和工艺因子、增大数值孔径来提升光学投影光刻的分辨率。随着数值孔径的增加，光的偏振特性对成像的 影响越来越大。通过分析偏振光的成像特性，控制照明的偏振方向，可以延伸光刻的分辨率。运用光的干涉原理 分析了偏振光影响成像质量的原因，结合阿贝成像原理与偏振的矢量特性对偏振光的成像进行了仿真，比较了不 同偏振照明下的成像对比度及焦深。结果表明，对图形选取相应的偏振照明，可以改善成像质量。 关键词：偏振成像；大数值孔径；光刻 中图分类号：O436.1; O436.3 文献标志码：A doi：10.3969/j.issn.1003-501X.2011.12.007 Analysis on High Numerical Aperture Polarized Imaging LIU Yong 1,2，XING Ting-wen1，YANG Xiong1 ( 1. Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China; 2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China ) Abstract: The resolution of lithography has become higher and higher to satisfy the demand of the continuous reduction of integrated circuit critical dimension (CD). As to the Rayleigh criterion, the resolution of optical projection lithography can be enhanced by reducing the wavelength, lowering the process factor and enlarging the numerical aperture (NA). As NA becomes larger, the polarization of light affects the imaging more significantly. By using the polarized illumination, the resolution can be improved. The reason why the polarization of light affects the imaging is analyzed by interference principle. The imaging of different polarized light is simulated with the Abbe’s theory of image formation and vector’s property. The image contrast and Depth of Focus (DOF) under different polarization are compared. The result shows that imaging performance can be improved by optimizing the polarization of illumination. Key words: polarized imaging; high NA; lithography 0 引 言 集成电路的特征线宽从最初的微米量级发展到了现在的 20 nm 左右，不断缩小的线宽对光刻机提出了 越来越苛刻的要求。由于衍射受限，所有的光学系统都存在着分辨极限，这一极限由瑞利判据来决定。光 学投影光刻也不例外，其能分辨的最小特征线宽为[1] CD = k 1λ / NA (1) 其中：k1 为工