中国科学院光电技术研究所微细加工光学技术国家重点实验室, 四川 成都 610209
针对现有同轴检焦方法如临界角法、博科刀口法、针孔法以及像散法等容易受光强变化的影响,且对系统装调有较高要求的问题,提出一种基于差动调制度解析的同轴检焦方法。通过物理光栅对成像空间进行编码,并采用傅里叶变换解析经基片高度调制后的编码图像调制度分布,结合差动探测系统实现对基片高度的精确测量。理论与实验表明,采用数值孔径为0.9、放大倍率为100的物镜,检焦精度优于10 nm。本文所提的检焦方法无需复杂光学元件,具有结构简单、测试精度高等优点,将为新型光刻技术提供一种新的高精度同轴检焦手段。
测量 同轴检焦 光刻 傅里叶变换 调制度
Author Affiliations
Abstract
School of Physics and Opto-Electronics Engineering, Ludong University, Yantai 264025, China
We propose a metalens for coaxial double wavelength focusing. One focusing spot is a circular solid spot, and the other focusing spot is a doughnut-shaped spot that is circling the solid spot. The designed metalens was composed of a meta-molecular nanostructured cell array. Each meta-molecular nanostructured cell was divided into four squares. Two slots with exactly the same shape, but usually with the rotation angle measured clockwise from the positive x axis, are etched into the gold film in two diagonally connected squares. Another two slots with the same shape but with the rotation angle measured counter-clockwise from the positive x axis are etched into another two diagonally connected squares in the same cell. The lasers with two different wavelengths are transformed into right-handed and left-handed circularly polarized beams, respectively. The two sets of slots with different azimuthal rotations modulated the phases of incident right-handed and left-handed circularly polarized beams independently. The numerical simulation with finite-difference time-domain (FDTD) software was carried out, and the experimental verification was also implemented. Both the experimental result and the numerical simulation agree well with the theoretical design.
metalens coaxial focusing double wavelengths Chinese Optics Letters
2020, 18(4): 042401
1 中国科学院理化技术研究所, 北京 100190
2 中国科学院光电技术研究所, 四川 成都 610209
3 中国科学院大学, 北京 100049
针对现有离轴检焦技术在浸没式光刻方法中的局限性,提出了一种新的基于干涉的同轴检焦方法。测量光通过光刻物镜入射到硅片表面,在硅片表面反射后再次经过光刻物镜后,测量光和参考光产生干涉条纹,并被CCD接收,从而将硅片的离焦量信息调制在干涉条纹的相位信息中。通过对干涉条纹的相位提取,即可获得硅片的离焦量。仿真结果表明,该方法可以达到λ/25(λ=632.8 nm)的检焦精度,并具有良好的抗噪性,满足浸没式光刻高精度、实时、非接触焦面测量的要求。
测量 同轴检焦 干涉 傅里叶变换 离焦量 中国激光
2013, 40(12): 1208005