基于变量分离分解法的极紫外光刻三维掩模快速仿真方法

Fast Simulation Method of Extreme-Ultraviolet Lithography 3D Mask Based on Variable Separation Degration Method

提出了一种基于分离变量法的极紫外光刻三维掩模衍射谱快速仿真方法,在保证一定仿真精度的前提下提高了仿真速度。该方法将三维掩模分解为2个相互垂直的二维掩模,对2个二维掩模采用严格电磁场方法进行衍射谱仿真并将结果相乘以重构成三维衍射谱。以6°主入射角、45°线偏振光照明及22nm三维方形接触孔掩模为例,在入射光方位角0°~90°变化范围内,相同仿真参数下,该方法的仿真结果与商用光刻仿真软件Dr.LiTHO的严格仿真结果相比,图形特征尺寸误差小于0.21nm,仿真速度提高约65倍。在上述参数下,该方法与Dr.LiTHO的域分解方法及基于掩模结构分解法等快速方法相比,仿真精度和速度均提高1倍以上。该模型无需参数标定,适用于矩形图形的三维掩模快速仿真。

A fast simulation method based on variable separation is proposed for 3D mask diffraction in extreme- ultraviolet lithography （EUVL）. The method achieves higher simulation speed while maintaining a good simulation accuracy. In this method, the 3D mask is decomposed into two orthogonal 2D masks. The diffraction spectrum simulation on two 2D masks are carried out through rigorous electromagnetic method. The results are then multiplied to reconstruct the three-dimensional diffraction spectrum. We set a premise of 6° main incident angle, 45° linearly polarized light illumination and 22 nm 3D square contact hole mask. Azimuth angle is ranging from 0° to 90°. Under the same simulation parameters, the simulation results of this method are compared with the rigorous simulation results of commercial lithography simulation software Dr. LiTHO. The errors of the simulated critical-dimension of the proposed method are within 0. 21 nm, and the simulation speed is about 65 times faster. Under the above parameters, the proposed method is compared with the domain decomposition method of Dr. LiTHO and a fast method based on mask-structure decomposition. The results show that the simulation accuracy and speed are improved more than double. The method needs no calibrations for model parameters and suits fast simulations of 3D masks that contain rectangular patterns.