基於石英音叉之原子力顯微鏡之開發

Abstract

原子力顯微鏡(Atomic force microscopy, AFM)利用一極尖之探針掃描帶測物表面，可達到奈米級解析度，並能結合多種模式用以量測不同之表面物理量。多探針原子力顯微鏡可同時對多區域進行量測，並可用於量測奈米尺度下之表面電性，然而其複雜度亦高於一般原子力顯微鏡。一般原子力顯微鏡係利用雷射光偏折方法量測探針之形變，然而雷射光偏折光路體積較大，在多探針系統中可能會造成機械干涉。此外，每組的光路雷射光訊號亦可能會出現互相干擾的情況，進而影響量測精度。本研究選擇石英音叉(Quartz tuning fork)作為感測元件，並結合自製鎢針建構一原子力顯微鏡。在鎢針製作上，透過改善蝕刻步驟，可穩定製作針尖小於20 nm之鎢針。實驗中對PG標準片(Platinum Coated Calibration Grid, Digital Instrument)進行掃描，結果可看到週期性表面結構。

Atomic force microscopy (AFM) uses a very sharp probe to scan the measured surface at nanoscale. Moreover, multiple physical quantities are available through diverse operating modes. Multi-probe AFM equips abilities of surface imaging and electrical property measurement on multiple regions simultaneously. However, the complexity of the multi-probe AFM is higher than common AFMs. Generally, AFMs use the laser beam deflection method to measure the deformation of the probe. However, the optical path of the beam deflection system is bulky for the multi-probe AFM, which may cause mechanical interference. In addition, the laser light scattering from different optical paths may also interfere with each other, thus affecting the measurement accuracy. In this study, a quartz tuning fork was selected as the sensing element and combined with a homemade tungsten probe to construct an AFM. By improving the etching method to manufacture the tungsten probe, the tungsten tip with a tip radius less than 20 nm can be routinely produced. In the experiment, a standard PG sample was scanned, and the periodic surface structures can be imaged.