大数值孔径下的偏振成像分析

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.%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.