高深寬比微結構之創新光學散射關鍵尺寸量測技術

Novel Scatterometry Technique for Critical Dimension Metrology of High-aspect-ratio Microstructures

簡維信(Wei-Hsin Chein) ； 楊福生(Fu-Sheng Yang) ； 傅子英(Zi-Ying Fu) ； 陳亮嘉(Liang-Chia Chen)

《科儀新知》 235期 (2023/06) Pp. 76-87

摘要

本研究發展了一創新之光學關鍵尺寸量測（OCD）系統與技術，用以克服目前於先進封裝製程中，具高深寬比之微結構難以使用非破壞性檢測的困境。結合光譜反射術與光學散射術，並利用雷射寬頻光源的高空間同調性所設計之創新顯微光學架構，此技術可大幅提升量測之光效率，並在量測範圍上可實現單一結構的量測，避免了現存之光學量測技術限於量測多個結構之平均資訊的缺點，此為本技術的關鍵突破和特點。通過反向優化的最佳化工程，實驗驗證結果表明，本系統可同時量測線寬與線距為1μm、深寬比為3：1之RDL結構的多項關鍵尺寸資訊。

並列摘要

In this study, we proposed a novel optical critical dimension (OCD) metrology system for nondestructive inspection of high-aspect-ratio (HAR) microstructures used in advanced packaging processes. The proposed system involves the integration of spectral reflectometry and scatterometry techniques, and incorporates the high spatial coherence of a broadband laser source for optimal beam shaping. The proposed technique significantly enhances the measurement light efficiency and enables single-structure measurements, addressing the limitations of existing optical metrology techniques that rely on average information from multiple structures. With the proposed model-based measurement scheme for solving an inverse problem, experimental tests demonstrate that multiple CDs of a RDL structure with a fine nominal linewidth and spacing of 1 μm and an aspect ratio of 3:1 can be accurately measured.