二维计量型平面光栅的设计  

Design of Two-Dimensional Metrological Planar Grating

作　　者：袁伟 朱煜[1] 张鸣[1] 王磊杰 Yuan Wei;Zhu Yu;Zhang Ming;Wang Leijie(Department of Mechanical Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学机械工程系,北京100084

出　　处：《光学学报》2023年第19期24-32,共9页Acta Optica Sinica

摘　　要：针对二维计量型平面光栅的设计和加工中工艺参数复杂的难点,本文基于电磁波时域有限差分方法,对硅基二维平面光栅的设计仿真进行了探索和研究,并进行了工艺实验验证。围绕平面光栅对衍射效率、衍射效率均衡性等指标的高要求,对不同结构、槽深和占空比下二维光栅偏振衍射效率受到的影响和变化规律进行了探索。仿真和实验结果表明,在占空比45.0%~46.7%附近,随着槽深增大,S偏振衍射效率逐渐减小,P偏振衍射效率逐渐增大;光栅槽深在260 nm附近时,不同偏振衍射效率可以达到平衡,带圆角的梯台结构光栅模型与实际工艺结果相近,衍射效率和偏振衍射均衡性等符合设计要求。仿真结果与实际工艺结果基本一致,表明其精度满足要求,大幅度提高了平面光栅设计和加工的效率。Objective The design and manufacturing technology of two-dimensional metrological planar gratings is complex and difficult.Design indicators and processing accuracy of two-dimensional(2D)gratings are important factors determining the performance of planar grating measurement systems.The grating type,grating pitch,groove depth,duty cycle,and characteristics of surface coating materials exert influence on diffraction efficiency and diffraction efficiency equilibrium.There are many parameter combinations and manufacturing methods for gratings.The development and process optimization of gratings feature long cycle time and low efficiency.Our purpose is to propose an accurate design and simulation method for two-dimensional planar gratings to provide sufficient accurate and fast support for grating development,shorten the cycle time of the design and processing of planar gratings,and improve development efficiency.Methods The design simulation of a silicon based two-dimensional planar grating is studied through the electromagnetic finite-difference time-domain(FDTD)method,and the simulation results are verified by experiments in this study.For two-dimensional grating structures,the FDTD algorithm only needs to simulate the smallest repeatable element with periodic boundary conditions.The calculation speed and accuracy meet the requirements and have been applied and verified in some grating simulations.By approximating and iterating the Maxwell equations in three-dimensional space,we can obtain the spatio-temporal changes in electromagnetic fields.One approximation method is called the central difference method.By linear interpolation approximation of physical quantities and selecting the appropriate truncation error level,high-precision approximation results can be obtained.The grating diffraction simulation in this study employs FDTD Solutions software and the grating unit in the simulation model consists of two parts,and the upper part is a columnar shape compatible with semiconductor technology.In this study,three

关 键 词：光栅设计 光栅仿真 光栅制造 衍射光栅 衍射效率 

分 类 号：O436[机械工程—光学工程]