摘要
随着半导体、光电子技术的快速发展,紫外到中红外不同波段的薄膜材料被广泛应用,而薄膜厚度、折射率、消光系数等参数的高精度测量是上述器件质量和性能提高的关键。而光谱椭偏技术是其检测的最佳手段。但现有光谱椭偏测量技术无法同时实现紫外-可见-短波红外宽波段透反射多角度测量,为此提出一种基于光栅+傅里叶光谱的宽波段大角度光谱椭偏测量技术。紫外-短波红外波段UV-SWIR(192~2100 nm)采用光栅光谱椭偏技术,短波红外-中红外波段SWIR-MIR(2000~3200 nm)采用傅里叶光谱椭偏技术,两个波段核心是探测光谱方式和位置不同,UV-SWIR波段的光栅光谱测量在检偏臂后端,SWIR-MIR波段的傅里叶干涉在起偏臂前端。为实现大角度测量,整个系统采用卧式旋转方式,两个波段起偏固定不动,检偏臂和样品台可大角度旋转,实现192~3200 nm宽波段、15°~90°大角度光谱椭偏系统集成。搭建原理样机,对Si基底上不同薄膜材料、不同厚度、不同膜层样片进行测量,其中用SiO_(2)-Si(薄膜为电介质)、ZnO-Si(薄膜为半导体)、PI-Si(薄膜为聚合物)、Si_(3)N_(4)-Al_(2)O_(3)-Si(电介质双层膜)、Au-SiO_(2)-Si(金属电介质双层膜)进行实验验证,并分别对样片穆勒矩阵M_(S)中的N=cos2Ψ、C=sin2ΨcosΔ和S=sin2ΨsinΔ与波长的关系进行测量,进而获得光谱椭偏参数Ψ和Δ,结合光谱椭偏理论拟合反演得到样片薄膜厚度。为验证该方法和系统的重复测量精度,对上述样片各进行30次重复测量实验。实验结果表明,该宽波段光谱椭偏系统的薄膜厚度测量精度优于0.7 nm,厚度重复性测量精度可达0.04 nm。该光谱椭偏测量技术可根据不同材料选择最优的光谱波段,进而提高其对更广泛材料类参数的测量精度,因此在高精度、宽波段、大角度薄膜椭偏测量领域具有重要的应用前景。
With the rapid advancement of semiconductor and optoelectronic technologies,materials operating across the ultraviolet(UV)to mid-infrared(MIR)spectrum have found widespread application.Accurate characterization of thin film parameters,such as thickness,refractive index,and extinction coefficient,is critical for optimizing device performance.Spectroscopic ellipsometry is the most effective technique for such measurements;however,existing methods struggle to achieve wide-band,multi-angle transreflectance measurements across the UV-visible-shortwave infrared(SWIR)range.To address this limitation,we propose a novel wide-band,large-angle spectroscopic ellipsometry system that integrates grating and Fourier spectrometry.Grating-based spectral ellipsometry is employed for the UV-SWIR range(192~2100 nm),while Fourier spectral ellipsometry covers the SWIR-MIR range(2000~3200 nm),extending the measurement capability across a broad spectral window.The detection approach differs between the two bands:grating spectral measurements are performed at the rear of the bias detection arm,whereas Fourier interference occurs at the front.A horizontal rotation mechanism is introduced,allowing large-angle measurements.In this design,the polarizing arms remain fixed.In contrast,the analyzer arm and sample stage rotate over a broad angular range,enabling integrated measurements from 192 to 3200 nm and incident angles between 15°and 90°.A prototype system was constructed and applied to a variety of thin films on silicon substrates,including SiO_(2)-Si(dielectric),ZnO-Si(semiconductor),PI-Si(polymer),Si_(3)N_(4)-Al_(2)O_(3)-Si(dielectric bilayer),and Au-SiO_(2)-Si(metal-dielectric bilayer).The relationships between N=cos2Ψ,C=sin2ΨcosΔ,and S=sin2ΨsinΔ in the Mueller matrix were measured and used to extract the ellipsometric parameters Ψ and Δ.Film thicknesses were then obtained through spectral ellipsometry modeling and fitting.System repeatability was assessed by performing 30 repeated measurements per sample,yielding a thickness measurement accuracy better than 0.7 nm and a repeatability of 0.04 nm.This technique enables the flexible selection of the optimal spectral range,depending on the material,significantly improving measurement accuracy and versatility.It holds great promise for high-precision,wide-band,and large-angle thin-film ellipsometry applications.
作者
张瑞
白沁
徐承雨
王赛飞
孔泉慧子
薛鹏
王志斌
ZHANG Rui;BAI Qin;XU Cheng-yu;WANG Sai-fei;KONG Quan-huizi;XUE Peng;WANG Zhi-bin(Technology Innovation Center of Shanxi Provincial for Intelligent Microwave Photoelectric,North University of China,Taiyuan 030051,China;School of Information and Communication Engineering,North University of China,Taiyuan 030051,China)
出处
《光谱学与光谱分析》
北大核心
2025年第10期2930-2934,共5页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(62105302)资助。
关键词
光谱椭偏
宽波段
大视场
光栅及傅里叶光谱
Spectral ellipsometry
Wide-band
Large-angle
Grating and Fourier spectrometry
