新型原子力顯微鏡系統之設計與控制

Design and Control of Novel Atomic Force Microscope Systems

洪紹剛(Shao-Kang Hung)

指導教授 ： 傅立成

國立臺灣大學/電機資訊學院/電機工程學研究所/博士(2007年)

https://doi.org/10.6342/NTU.2007.00961

摘要

本論文提出三種新型原子力顯微鏡（atomic force microscope）系統。首先是雷射光路追蹤型原子力顯微鏡，其特殊的光學感測機制可以追蹤往復運動中的探針，進而量測探針懸臂的撓曲，其偽撓曲（false deflection）現象已最小化。如此一來，樣品不需運動，故掃描速度不會受限於樣品之質量。其次提出的是利用光碟讀取頭來量測探針懸臂撓曲的掃樣品型原子力顯微鏡。既然光碟讀取頭輕得足以快速往復掃描，本研究中所發展的第三種系統回到掃針型原子力顯微鏡。在此嶄新的系統中樣品完全靜止，也沒有偽撓曲現象。
為了實現上述系統，我們設計了一種適應性滑動模式控制器（adaptive sliding-mode controller），用以取代傳統上人工手動調整參數的正比積分控制器（proportion-integration controller）。使用這種控制器，任何無經驗的使用者都可以輕鬆得到高品質的原子力顯微鏡影像。隨後我們提出螺旋掃描法，它實現了平滑的圓形掃描。這種新方法可以提高掃描速度、降低影像扭曲、減少對壓電掃描器的傷害。最後，為了展現系統的性能，我們執行了一系列的實驗。實驗結果顯示最大暫態追蹤誤差為 ±6奈米，穩態誤差（垂直方向解析度）為 ±1奈米，取像速度為每幅157秒。

關鍵字

原子力顯微鏡 ； 適應性控制 ； 滑動模式控制 ； 螺旋掃描法 ； 光碟讀取頭 ； 雷射追蹤型原子力顯微鏡 ； 掃樣品型原子力顯微鏡 ； 掃針型原子力顯微鏡

並列摘要

Three novel atomic force microscope (AFM) systems are proposed in this dissertation. The first one is a laser tracking type AFM. In this system, the laser detecting mechanism is specially designed to track the scanning probe, and then measure the deflection of the cantilever with minimized false deflection. Under such circumstance, the sample can be kept stationary, and the scanning speed will not be limited by the weight of the sample. Contrary to scanning probe notion, the second system proposed here is a scanning sample type AFM equipped with a CD/DVD pick-up-head (PUH) used to measure the deflection of the cantilever beam of the probe. Since the PUH is light enough to be carried for rapid scan, the third system developed in this research is back to a scanning probe type AFM. For this novel system, the sample is fully stationary, and there is no false deflection in this system.
To implement the above systems, we have designed an adaptive sliding-mode controller which replaces the traditional manually-tuned proportion-integration (PI) controller. Using this controller, any inexperienced user can still obtain high quality AFM images without difficulty. Next, a spiral scanning method is devised to realize a smooth circular scan. This novel method can achieve high speed scanning, low image distortion, and low damage to the piezoelectric scanner. Finally, to demonstrate the performance of the proposed systems, numerous experiments have been conducted. The experimental results show that he maximum transient tracking error is ±6 nm, the steady state error (topography resolution) is ±1 nm, and the imaging speed is 157 s/frame.

並列關鍵字

atomic force microscope (AFM) ； adaptive control ； sliding-mode control ； spiral scanning method ； compact disk (CD)/ digital versatile disk (DVD) pickup head (PUH) ； laser tracking type AFM ； scanning sample type AFM ； scanning probe type AFM

參考文獻

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