應用於非等距採樣白光干涉形貌量測演算法之研究

白光干涉近年來廣泛用於微奈米結構的形貌，在精密量測過程中，微細的環境振動會影響量測工件之準確度，所以處理振動造成的偏移量為白光干涉精密量測必要的步驟。處理振動偏移量的方式有兩種，一種方式為在量測過程中主動補償振動偏移量；另一種方式為偵測振動偏移量，再利用適當的演算法補償修正。前者利用系統回授的方式驅動壓電材料侷補償振動偏移，不過侷限於壓電材料之運動響應頻寬偏低，會造成系統補償延遲。因此，本研究使用嵌入式控制器同步擷取高同調干涉條紋及白光干涉條紋，其中高同調干涉訊號配合相移演算法可即時偵測振動偏移量，再將振動資訊與白光干涉訊號結合進行影像形貌分析。本研究中先針對高同調性干涉條紋進行訊號處理，可以精確量測影像取樣高度。根據白光干涉定理可知，白光干涉訊號最大峰值位置即為待測物之高度，所以白光干涉演算法為估測白光干涉峰值位置之手段。一般白光干涉量測建立在等距採樣的條件，但白光干涉垂直掃描系統中獲得的振動資訊與白光干涉訊號相互配合，會產生出一個非等間隔、非週期性及非對稱採樣之數值模型。本研究採用白光干涉曲線擬合演算法進行估測峰值之位置，該演算法為基礎之函式擬合模型，可應用於非等距、非對稱之採樣訊號，藉由演算法估算白光干涉峰值之位置，進而重建待測物之三維形貌輪廓，本研究發展之演算法相較於同光學系統中現有之演算法有較優的精準度。

關鍵字

白光干涉測量；曲線擬合

並列摘要

The white-light interferometry has been broadly used in micro/nano-structure in recent years. As environmental vibration affects the measurement accuracy, it is necessary to modulate offset-compensation of vibration. There are two methods for compensating the displacement of vibration. The first method is to use the PZT as feedback. The other method is to detect the displacement and use the appropriate algorithm to attenuate and correct adjustments. Of the two methods, the former relies on the accuracy of PZT. Its limitation is that the bandwidth of PZT stays low, causing delay to the compensatory system. The aim of this study is to use the embedded system in hope of achieving high-coherence by effectively mastering white-light interference fringe to calculate the offset with phase-shift algorithm. It focuses on signal processing with high-coherence interference fringe, which can be sampled in high and accurate resolution. According to the white-light interference principle, the highest peak of white-light interference fringe is the height of the object. Hence, it can be used as a method to estimate the peak using mathematical algorithm. White-light interferometry measurement assumes equidistant sampling condition, but the measurement is in aperiodic waveforms. This study estimated the peak of fringe which is sampled in unequal, aperiodic and asymmetric. In order to obtain the peak position of the white-light interference, the study uses white-light curve fitting algorithm for fitting sampling points, which can be applied to unequal, asymmetric signals. By using the algorithm to estimate the peak point of the white-light interference fringe, this study reconstructs the three dimension outlines of components to be analyzed. The algorithm developed by this study can calculate with the standard deviation of 2.22 nm, which is one of the better algorithms so far.

並列關鍵字

white-light interferometry ； curve fitting

參考文獻

[1] 何仁杰，應用於白光干涉測量之嵌入式抑制線上振動系統開發，碩士論文，國立台北科技大學機電整合研究所，台北，2011

[2] D. Wu et al., “Transverse spatial phase-shifing method used invibration compensated interferometer, ” Optik 115, No. 8, 2004, pp. 343-346

[3] T. Yamauchi et al., “Measurement of topographic phase image of living cells by white-light phase-shifting microscope with active stabilization of optical path difference,” Proc. SPIE 6429, 64291Q, 2007, pp. 1354-1358

[4] J. Schmit et al., “White light interferometry with reference signal,” Proc. Of SPIE, Vol. 4777,2002,pp.102-109

[5] A. Olszal and J. Schmit, “Scanning interferometry with reference signal, ” U.S. Patent,2002, No.0196450

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應用於非等距採樣白光干涉形貌量測演算法之研究

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