隨著時代的發展，奈米科技已經成為我們生活周遭不可或缺的技術，多年來隨著技術的發展成熟，多孔矽奈米技術已經成為半導體製程及能源產業中舉足輕重的重要角色。而金屬輔助化學蝕刻可利用兩步法(Two-step method)製程製備出多孔矽結構，其製程簡易及成本較低等優點於近年研究中得到相當的注目。在生醫方面，微流道為備受關注的主題，其中研究微流體需要探討流體於材料的親疏水之濕潤性質，若需要在微小流體上進行遷移動作，可以透過改變物體表面之微奈米結構改變其濕潤性。

本文利用金屬輔助化學蝕刻，其製程簡易且不需在高壓或高溫環境下即可進行實驗之特點，先以無電鍍沉積法進行銀粒子沉積，再利用蝕刻液使銀粒子於矽表面發生氧化反應從而進行非等向性蝕刻，研究其蝕刻液於常溫及變溫情況下，對於蝕刻深度及結構之影響。實驗結果顯示於適當蝕刻溫度可給予蝕刻結構深度與孔隙率良好之助力，再將蝕刻後之試片進行接觸角量測，探討不同表面結構對於液珠接觸角之影響。

最後綜合上述實驗結果，以將矽試片拉出蝕刻液之方法，製備出具有梯度結構之多孔矽試片，並觀察其接觸角與液珠滑動之情形。實驗結果顯示，液珠於梯度結構表面之驅動力過小，但透過一頃斜平台轉動角度使液珠滑動可得知，液珠於大接觸角端所需滑動之臨界角度小於小接觸角端之滑動臨界角，並且其液珠加速度之提升更為快速。

In recent years, nanoporous silicon plays an important role in the semiconductor industry and energy industry. Two-step metal assisted chemical etching method has the advantages of low cost and simple processes. In biomedical and microfluidic systems, the hydrophobicity of materials must be considered. We can control a fluid drop to move on a solid surface by changing the hydrophobicity of surface material with nano structures.

We deposit silver particles with electro-less plating deposition method, followed by the anisotropic etch of the silicon surface by oxidation of etchant and silver particles. We apply different temperature to see how it affects the etching depths and the structures. Appropriate temperature helps to achieve best etching depth and porousity. We also determine the effects of different surface structures on droplet contact angles.

We find that the driving force to make the droplet move is too small on the nano porous silicon surface we made. So we use a tilt platform to increase the driving force to observe the effects easily. The critical angle at the larger contact angle side is smaller than the one at the smaller contact angle side, and is faster in the increase of the acceleration of the droplet.

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