創新式白光干涉橫向掃描三維輪廓量測儀

Innovative 3-D Surface Profilometer Using White Light Lateral Scanning Interferometry

林宜萱(Yi-Hsuan Lin)

指導教授 ： 陳亮嘉 ； 賴明鈞

國立臺北科技大學/機電學院/機電整合研究所/碩士(2009年)

摘要

本研究提出一創新式白光干涉橫向掃描 (White Light Lateral Scanning Interferometry, WLLSI) 三維輪廓量測儀，研究創新性為可用於大範圍線上物體表面微結構三維形貌重建量測，不需繁雜局部縫合技術，量測更有效率。傳統白光垂直干涉掃描 (Vertical Scanning Interferometry, VSI) 量測系統，受限於不同干涉物鏡之視野範圍，物體量測之範圍 (Field of View, FOV) 將受限制。在進行垂直掃描取得干涉訊號時，易受外來振動因素影響且量測過程較耗時，故不適於大範圍線上檢測。另外傳統橫向掃描 (Lateral Scanning Interferometry, LSI) 系統，是將整個干涉系統傾斜一角度，使光軸與待測物掃描方向夾一角度，藉此特性進行橫向掃描以重建物體三維形貌。因系統傾斜一角度，使用較高倍率物鏡時，將有待測物與干涉物鏡碰撞問題。
為解決上述問題，本研究提出創新式WLLSI技術，以控制干涉物鏡中參考鏡傾斜角度，取代傳統LSI方法。將待測物置於傾斜的干涉同調範圍內，並以橫向掃描進行待測物之三維形貌重建。另外提出一深度位置校正方法，利用參考鏡進行垂直掃描，找出CCD與干涉訊號峰值之對應關係，進而求得精確的深度資訊。為驗證系統之可行性，使用標準階高塊規與業界樣本(BEF及微結構物體)進行重覆性量測，以驗證量測之精準度與穩定性。實驗結果證明，重覆性之一個標準差中可控制在60奈米以下，且最大量測深度為27.21μm。驗證本系統相較於傳統橫向或垂直掃描法，不但有效解決大範圍線上量測的效率問題且可維持一定程度的精準度。

關鍵字

白光干涉 ； 表面輪廓尺寸 ； 橫向掃描 ； 垂直掃描

並列摘要

An in-situ 3-D surface profilometer for reconstructing micro surface profiles with a long depth measuring range and a nano-scale resolution was developed using innovative white light lateral scanning interferometry (LSI). Current measuring field of view (FOV) of conventional white light interferometers is currently limited by microscopic views of the existing interferometric objectives, such as Michelson, Mirau or Linnik design. Moreover, vertical scanning operation required for acquiring volumetric interferometric data is extremerely time consuming and makes white light vertical scanning interferometry (VSI) infeasible for in-situ automatic optical inspection (AOI) on micro 3-D structures. The traditional LSI methods were mainly developed by tilting the whole optical axis with respect to the scanning direction of a sample’s surface underlying inspection, in which it has one inherent difficulty in effective collision avoidance between the optical objective and the object’s surface. To resolve this, a new white light LSI method was developed here by controlling the tilting angle of the reference mirror in the interferometric objective. With the proposed optical configuration, the surface is inspected at a tilting angle with respect to the maximum coherence plane of the interferometric system along its lateral scanning direction when the objective lies perpendicularly with the tested surface. In addition, a calibration method was developed to establish an accurate mathematical mapping model between the object depth and the lateral axis. To evaluate the feasibility of the methodology, a calibrated step height was measured for evaluating the accuracy and repeatability. Some industrial samples, such as photon spacers and other microstructures fabricated by -nano imprinting processes, were measured to verify the actual performance on real components. It was found that the measurement repeatability was controlled less than 60 nm within one standard deviation for a maximum measurable depth of 27.21 μm.

並列關鍵字

white light interferometry ； lateral scanning interferometry (LSI) ； surface profiler ； vertical scanning interferometry (VSI)

參考文獻

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