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Nano In-Process Measurement of 3D Micro-Profile Using Optical Inverse Scattering

使用光学逆散射对 3D 微观轮廓进行纳米过程测量

基本信息

批准号：
11555043
负责人：
MIYOSHI Takashi
金额：
$ 6.59万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11555043/
关键词：
Optical Inverse Scattering Phase retrieval 3D Micro-Profile Nano in-process measurement Fourier transform Fraunhofer diffraction Optical measurement レーザー応用計測

项目摘要

A new optical measurement method, which can be applied to in-process measurement of three-dimensional micro-profiles with accuracy in the nanometer order, is proposed in this paper. The proposed method is called optical inverse scattering phase method and offers the advantage of measuring a three-dimensional profile within the whole area illuminated by the laser beam simultaneously. This means that no scanning process is required. The optical inverse scattering phase method is based on two principles, one is optical Fourier transform, the other is iterative Fourier phase retrieval algorithm. Employing Fourier phase retrieval algorithm, three-dimensional micro-profiles are reconstructed from only the Fraunhofer diffraction intensity measured by Fourier transform optical system. Computer simulations as well as actual measurements were performed for the verification of our proposed method. First, the simulation results suggested the capability for reconstructing three-dimensional micro-profiles with accuracy in the nanometer order. As a strategy to avoid stagnation of iterative algorithm, a new concept based on the design model of the workpiece and the Gaussian profile of the laser beam was also proposed. Next, in order to verify the feasibility of the optical inverse scattering phase method, the automated optical measuring system consisting of Ar ion laser, Fourier transform lens, CCD linesensor, EWS computer, etc., was developed and the measurement experiments were carried out for the ultra-precision grid pattern with the depth of 44nm and the pitch of 10μm. The experimental results showed that the proposed method makes it possible to reconstruct a micro-profile within the whole illumination area equivalent to the laser beam diameter at one time without scanning.

提出了一种新的光学测量方法，可用于纳米级三维微轮廓的在线测量。所提出的方法被称为光学逆散射相位法，并提供了测量的三维轮廓内的激光束照射的整个区域内的同时的优点。这意味着不需要扫描过程。光学逆散射相位法基于光学傅里叶变换和迭代傅里叶相位恢复算法两个原理。采用傅里叶相位恢复算法，仅由傅里叶变换光学系统测量的夫琅和费衍射强度重建三维微轮廓。计算机模拟以及实际测量进行了验证我们提出的方法。首先，模拟结果表明，重建三维微观轮廓的能力，精度在纳米级。作为避免迭代算法停滞的一种策略，提出了一种基于工件设计模型和激光束高斯分布的新概念。其次，为了验证光学逆散射相位法的可行性，建立了由Ar离子激光器、傅里叶变换透镜、CCD线传感器、EWS计算机等组成的自动光学测量系统，并对深度为44nm、间距为10μm的超精密网格图形进行了测量实验。实验结果表明，该方法可以在不扫描的情况下，一次重建相当于激光束直径的整个照明区域内的微轮廓。