传统三维光刻矢量成像模型中将投影系统物方电磁场表示为二维形式，实现方式分为两种：采用局部坐标和忽略掩模衍射频谱的轴向分量。后者在浸没式光刻系统仿真中的适用性需要进一步分析。简述了忽略掩模频谱轴向分量的矢量成像模型和引入该分量的全光路三维光刻矢量成像模型，利用这两种模型和商业仿真软件，研究了掩模衍射频谱轴向分量对光刻胶中成像特征尺寸的影响并对结果进行了讨论。研究结果表明，相干照明和部分相干照明条件下，掩模衍射频谱轴向分量对光刻成像的影响随着数值孔径的变化趋势存在较大差异。这说明相干照明下的分析结论并不适用于部分相干照明条件，且只有全光路三维矢量成像模型才能满足浸没式高分辨光刻仿真的要求。

Traditional three-dimensional (3D) vector imaging models treat the electric field distribution in the entrance pupil of projector by transforming the distribution in the local coordinate or ignoring the axial component of the mask diffraction spectrum (MDS). The accuracy of the model with the latter should be discussed in immersion lithography. The traditional 3D vector imaging model and a modified 3D lithography imaging model which integrates all the vector effects of plane wave through the whole imaging system are introduced. Then the influence of the axial component of MDS on the lithography imaging performance is analyzed by the modified imaging model and the resist model of commercial software PROLITHTM. The results are discussed by using frequency spectrum analysis. The simulation results show that the accuracy of traditional 3D vector imaging model is degraded in hyper numerical aperture (NA) system for the axial component of MDS on the entrance pupil of projector cannot be ignored any more in immersion lithography. This demonstrates that only the modified 3D imaging model under partially coherent illumination condition can satisfy the requirement of hyper NA lithography simulation.