Adaptive Tilting Angles to Achieve High-Precision Scanning of a Dual-Probe AFM

隨著奈米科技的進步，一些微結構的尺寸也不斷的縮小，因此如何精確的對這些微小結構或特徵進行量測已成為一個相當重要的議題，原子力顯微鏡是一種具有奈米級解析能力的量測儀器，近年來已廣泛應用於微奈米結構的輪廓量測，然而，由於傳統原子力顯微鏡的單一探針傾角設計，在量測時探針和樣本的存在相對角度的誤差，進而造成掃描結果在樣本側邊和邊角的影像扭曲。 為了改善上述的問題，在本研究中，我們提出自主適應性傾角演算法結合自主開發之雙探針原子力顯微鏡系統，藉此達到對未知樣本的線上樣本側邊角度估測，經由所提出的演算法，我們能決定兩根探針在每一條掃描線所應該具有的傾角角度；再者，經由我們所設計的探針旋轉機構，探針的傾角能夠在掃描期間改變，結合雙探針架構，我們的原子力顯微鏡系統只需一次掃描就能獲得高精確的樣本輪廓影像。從一系列的實驗結果能證實本研究所提出的方法能有效消除樣本側邊的失真現象。With the deep development of micro- and nano- frabricated techniques, the feature size of the sample has become smaller and smaller. There is an important issue to measure this kind of small object in nano-scale. Atomic force microscopy (AFM) is a powerful measurement tool which has been wildly used in micro-fabricated structure inspection recently. However, since the fixed tilting angle of the probe employed in traditional AFM, the corner and sidewall of the scanned sample image would be distorted. To overcome the problem, in this works, an adaptive tilting angle algorithm operated on a self-designed dual-probe AFM system is presented to achieve on-line sidewall estimation for general sample profile. Through the use of adaptive tilting angle algorithm, the tilting angles of dual probes for each scan line can be determined. Above all, the probe-tilt mechanism is designed which allows the AFM system to change the tilting angles of the probe during the scanning process such that the dual-probe structure can acquire a complete high precise image in a single scan. The experimental results show outstanding performance of sidewall measurement and the high-precision image obtained by the proposed method