結合建構光發展超解析白光干涉顯微術之研究

Research on the development of super-resolution white light interferometric microscopy with structured illumination

林允丞(Yun-Chen Lin)

指導教授 ： 陳亮嘉

國立臺灣大學/工學院/機械工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202000374

摘要

因為工業製程的精進，工業元件的關鍵尺寸不斷縮小，因此元件的三維形貌尺寸依賴各式量測技術來達成，光學量測是一種最常見的量測方式，它是非接觸式量測且量測速度快，可以應用在產線上，白光干涉儀就是一種常見的奈米級量測儀器，其深度解析能力非常好。然而因為光學的特性，在水平解析度上被繞射極限所限制，在一定的尺度下就無法分辨，因此本研究開發一種提升水平解析能力的白光干涉三微形貌量測技術，在同樣N.A.的情況下增加系統解析能力。
為了增加橫向解析，本研究將白光干涉結合結構光投影顯微術，結構光投影顯微術是一種對待測物較無限制的超解析法，透過在待測物表面投影弦波並進行相位移，將收取的影像轉到傅立葉頻域處理，藉此解出高頻的訊號並重建成更寬廣的頻譜範圍，此方式結合白光干涉的深度解析能力，透過垂直掃描的方式來解出深度資訊，因為白光干涉的特性，其深度解析可以到達奈米級，因此這兩方法的結合可望細微結構的三維形貌量測上可以更加精準。
本研究對1.0 um的線寬樣品進行量測，可將傳統白光干涉系統未能解析的形貌特徵給重建出來，初步驗證了結構光投影顯微術可以有效提升三維形貌的水平解析能力。

關鍵字

繞射極限 ； 白光干涉 ； 結構光投影顯微 ； 超解析 ； 三維形貌量測

並列摘要

Due to the advancement of industrial processes, the critical dimensions of industrial components have been shrinking. The dimensions of 3D profiles can be measured by various methods. Optical metrology is one of the common methods in profile metrology. Because it is a non-contact method and with high measurement speed, it can be applied to on-line production process. White light interferometry is an optical method for surface profilometry in nanoscale and its depth resolution can reach to sub-nanoscale. However, its lateral resolution is limited by optical diffraction limit. When the dimension of a sample is beyond Rayleigh criterion, it can’t be resolved. To resolve this issue, this study develops a technique to improve the lateral resolution of white light interferometry. It can achieve better lateral resolution ability under the condition of same N.A. In order to improve the lateral resolution, in this work, white light interferometry is integrated with structured illumination microscopy (SIM). Structured illumination microscopy is a super-resolution method without the restriction of tested samples to be of biomaterials or similar ones. By projecting structured light and phase shifting, the high frequency information can be resolved in Fourier domain when the spectrum range of its virtual optical transfer frequency (OTF) is effectively extended by adding the first order spectrum information. With the combination of vertical scanning of white light interferometry, the depth resolution can achieve in nanoscale and the 3D topography of the micro structure with improved lateral resolution can be measured and reconstructed more accurately.
Proofed by the experiments, the developed method can reconstruct the unresolved topography by the traditional white light interferometric system on a 1.0 um line-width sample.

並列關鍵字

diffraction limit ； white light interferometry ； structured illumination microscopy (SIM) ； super-resolution ； 3D metrology

參考文獻

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