Study of Wide-Band and Large-Angle Spectral Ellipsometry Technique Based on Grating and Fourier Spectrometry
ZHANG Rui1, 2*, BAI Qin1, 2, XU Cheng-yu1, 2, WANG Sai-fei1, KONG Quan-huizi1, 2, XUE Peng1, WANG Zhi-bin1
1. Technology Innovation Center of Shanxi Provincial for Intelligent Microwave Photoelectric, North University of China, Taiyuan 030051，China
2. School of Information and Communication Engineering, North University of China, Taiyuan 030051, China
Abstract：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 (192～2 100 nm), while Fourier spectral ellipsometry covers the SWIR-MIR range (2 000～3 200 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 3 200 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 SiO2-Si (dielectric), ZnO-Si (semiconductor), PI-Si (polymer), Si3N4-Al2O3-Si (dielectric bilayer), and Au-SiO2-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.
Key words：Spectral ellipsometry;Wide-band; Large-angle;Grating and Fourier spectrometry
张 瑞，白 沁，徐承雨，王赛飞，孔泉慧子，薛 鹏，王志斌. 基于光栅+傅里叶光谱的宽波段大角度光谱椭偏技术研究[J]. 光谱学与光谱分析, 2025, 45(10): 2930-2934.
ZHANG Rui, BAI Qin, XU Cheng-yu, WANG Sai-fei, KONG Quan-huizi, XUE Peng, WANG Zhi-bin. Study of Wide-Band and Large-Angle Spectral Ellipsometry Technique Based on Grating and Fourier Spectrometry. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(10): 2930-2934.
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