在扫描干涉场曝光(SBIL)系统中, 曝光光斑尺寸对干涉条纹的拼接精度、光栅制作效率及干涉场质量有着十分重要的影响。为获取合理的曝光光斑尺寸, 基于高斯光束的传输规律及扫描拼接数学模型进行了数值模拟,讨论了曝光光斑尺寸对干涉条纹的非线性误差、刻线拼接误差和曝光对比度的影响。结果表明: 小尺寸曝光光斑比大尺寸曝光光斑更有利于控制干涉条纹的非线性误差; 由于存在周期测量误差, 小尺寸曝光光斑有利于减小拼接后的刻线误差并提高曝光对比度。针对SBIL系统设计了曝光光路, 并对所设计的光路进行了优化。对干涉场左右光斑形貌及干涉条纹相位的非线性误差进行了测量, 结果表明: 曝光光斑的束腰半径约为0.9 mm, 干涉条纹相位的非线性误差峰谷值为21.8 nm。

In a scanning beam interference lithography (SBIL) system, the exposure spot size has significant influence on the stitching accuracy of interference fringes, efficiency of grating fabrication and quality of interference field. In order to obtain a reasonable exposure spot size, the influence of exposure spot size on nonlinear error of interference fringe, line stitching error and exposure contrast is discussed by numerical simulation based on the transmission law of Gaussian beam and scanning stitching mathematical model. Results show that, compared with the large-sized spot, the small exposure spot is more conducive to controlling nonlinear error of interference fringe. Because there exists periodic measurement error, a small exposure spot helps to reduce the line error after stitching and enhance the exposure contrast. The exposure optical path of SBIL system is designed and optimized. The left and right spot morphologies of interference field and the nonlinear error of interference fringe phase are measured. Results show that the waist radius of exposure spot is about 0.9 mm, and the nonlinear error peak-valley value of interference fringe phase is 21.8 nm.