Optical Characterization of Nanofilms and Metalenses via Ellipsometry

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/97618

Title:	Optical Characterization of Nanofilms and Metalenses via Ellipsometry
Authors:	林柏亨;Po-Heng, Lin
Contributors:	光電科學研究所碩士在職專班
Keywords:	橢圓偏振量測;嚴格耦合波分析;先穎透鏡;色散模型;Ellipsometry;RCWA;Metalens;Dispersion model
Date:	2025-08-14
Issue Date:	2025-10-17 11:41:31 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究建立了一套整合橢圓偏振量測、Tauc–Lorentz 色散模型與嚴格耦合波分析法（RCWA）的完整工作流程，旨在全面性地表徵非晶矽薄膜以及奈米級週期性光柵結構。我們首先運用 Tauc–Lorentz 色散模型擬合非晶矽的橢圓偏振參數 Ψ 與 Δ 光譜，獲得最佳化的薄膜厚度（62.64 nm）與入射角度（60.52°）。所提取的介電常數進一步透過 Kramers–Kronig 關係驗證其物理自洽性。接著，利用 RETICOLO, 一套使用在 MATLAB 的 RCWA 求解器，我們系統性探討 60°–70° 入射角範圍、佔空比（0.3–0.7）、蝕刻深度（91–111 nm）以及光柵週期（726 nm 與 1033 nm）對 TE/TM 反射率以及橢圓偏振參數 Ψ 與 Δ 在 250–1200 nm 波段與內的影響。模擬結果與實驗數據展現出極佳的一致性，顯示在布魯斯特角附近 TM 波顯著抑制。最後，我們提出一套適用於先穎透鏡量測的多點、多角度量測策略：選擇 AOI = 60° 作為穩定的基線，以及 AOI = 70° 作為敏感檢測奈米級非均勻性的量測條件。此方法能為薄膜與奈米結構元件提供穩健的線上製程監控，並加速光柵與先穎透鏡的設計優化。;This work develops an integrated workflow combining spectroscopic ellipsometry, the Tauc–Lorentz dispersion model, and rigorous coupled-wave analysis (RCWA) to comprehensively characterize amorphous silicon thin films and nanoscale periodic grating structures. We first employ the Tauc–Lorentz formalism to fit ellipsometric Ψ and Δ spectra of amorphous silicon, achieving optimized film thickness (62.64 nm) and incidence angle (60.52 ° ). Physical self ‐ consistency of the extracted refractive index and extinction coefficient is confirmed via Kramers–Kronig relations. Next, using the RETICOLO RCWA solver, we systematically investigate the influence of 60°–70° AOI, duty cycle (0.3– 0.7), etch depth (91–111 nm), and grating period (726 nm vs. 1033 nm) on TE/TM reflectance and ellipsometric parameters across 250–1200 nm. Simulation and experimental data exhibit excellent agreement, revealing pronounced TM suppression at Brewster’s angle. Finally, we propose a multi‐point, multi‐angle measurement strategy for metalens metrology: AOI = 60° for a stable baseline and AOI = 70° for sensitive detection of nanoscale nonuniformities. This methodology offers robust in‐line process monitoring for thin ‐ film and nanostructured photonic devices and accelerates design optimization of gratings and metalenses.
Appears in Collections:	[Executive Master of Optics and Photonics] Electronic Thesis & Dissertation

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