以掃描穿隧顯微鏡在矽晶上進行奈米氧化加工之研究

Abstract

本實驗中利用掃描穿隧顯微鏡(Scanning Tunneling Microscope，STM)在矽(100)單晶表面長成奈米尺寸的矽氧化物。實驗結果顯示，進行氧化加工時的電壓值、穿隧電流值以及掃描線密度等均為重要的參數。此外由原子力顯微鏡(AFM)與掃描式電子顯微鏡(SEM)的分析檢測結果顯示，在氧化加工的過程中，探針的材質是影響加工電壓值的因素之一，當穿隧電流為2.0 nA時，對鎢(W)探針而言，長成理想的氧化圖案之電壓範圍在-0.6 V至-1.4 V之間；對鉑-銥(PtIr)探針而言，理想電壓範圍則在-1.0 V和-2.6 V之間。探針的尖銳程度對氧化物圖案的寬度與高度有直接的影響，須使用尖銳的探針才能長成高縱橫比的氧化物直線。最後，本實驗亦探討鎢探針的製備方法。

In this work, nanoscale oxide patterns were fabricated on H-passivated Si substrate by using a scanning tunneling microscope (STM) in air. It was found that the bias voltages, setpoint current and scan line density play important roles to form attainable oxide features. Characterization using AFM and SEM further revealed that the optimum bias voltage applied for patterning is related to the material species of tip rather than to the tip head sharpness. For W tips, oxide patterns with desired geometrical features can be obtained at the bias voltages ranging from -0.6 V to -1.4 V, while for PtIr tips, the bias voltages lie in between -1.0 V and -2.6 V at fixed tunneling current of 2.0 nA. On the other hand, the tip sharpness does affect the width and height of line patterns. When narrower oxide lines were desired, a sharper tip has to be used for STM patterning. In addition, we also demonstrated the method for W tip preparation.