高斯光在远离束腰位置能得到直线度极高的干涉条纹,基于此提出了一种基于远场干涉的新型扫描干涉场曝光(SBIL)系统。建立了条纹相位非线性误差关于高斯光束腰半径、入射角度及束腰到基底距离的解析表达式。通过数值仿真,详细分析了条纹相位非线性误差与上述参数的关系。研究结果表明,该光学系统可以有效地将条纹相位非线性误差限制在纳米量级,并具有光路简洁、装调误差宽容度较高的优点。适当缩短束腰到基底的距离,可有效解决曝光光斑边界处条纹相位非线性误差恶化的问题。

Extremely straight interference fringes can be formed at the position far away from the waist of Gaussian beams and based on this principle, a novel far-field-interference-based scanning beam interference lithography (SBIL) optical system is proposed. The analytic expression of the nonlinear error with respect to waist radius of Gaussian beams, the incident angle and the waist-to-substrate distance is established. By the numerical simulation, the relationships between the nonlinear error of fringes and the above parameters are analyzed in detail. The research results show that this optical system can effectively limit the nonlinear error of fringe phase to the nanometer scale, and possesses the advantages of simple optical path and high tolerance of assembly errors. The problem that the nonlinear error of fringes at the boundary of the exposure spot is deteriorated can be effectively solved if the waist-to-substrate distance is suitably shortened.