石英奈米針狀結構表面之潤濕性及遲滯性研究

陳新龍(Sin-Long Chen)

指導教授 ： 洪銘聰

國立中央大學/工學院/機械工程學系/碩士(2014年)

摘要

石英具有良好的熱穩定性、透光性、絕緣性及壓電特性廣泛應用於機械結構、光學元件及震盪元件。隨著微機電技術的進步，石英也開始應用於微機電系統元件上，在這些應用中其表面特性經常為重要考量的因素，表面潤濕性為化學檢測微系統及生醫晶片中重要的參數，於表面製作微奈米結構則為表面改質的有效方法。
本研究使用熱退火製備之白金奈米點作為遮罩，並利用氟化氫銨水溶液對石英晶圓進行濕式蝕刻得到奈米針狀結構，藉由掃描式電子顯微鏡觀察針狀結構形狀，再量測表面接觸角分析其與表面結構關係，並與理論模型進行探討。研究結果隨膜厚增加，奈米點粒徑隨之上升，而分佈密度下降。白金奈米點雖附著性較差但仍可阻擋蝕刻液，利用不同粒徑與分佈之奈米點，配合不同蝕刻時間即可在石英表面蝕刻出不同高度與分佈密度之結構。在靜態接觸角方面，量測結果與模型比對後發現液滴在此結構下會滲入至結構間並接觸到結構間底部，使接觸角下降。分析參數後得知接觸結構間底部面積比例隨分佈密度增加等比例下降；結構高度則影響下降的幅度，結構高度越高則下降幅度越大。在動態接觸角方面，具有結構之表面呈現相當大的遲滯現象，其原因可由液滴在表面的狀態作解釋，在此針狀結構表面液滴會滲入結構之中，使其不易於表面上移動。遲滯角隨表面粗糙度增加而變大，因其滲入結構的程度與表面粗糙度有關，當表面粗糙度上升時，液滴仍為部分接觸結構間底部的狀態，代表滲入的狀況更為嚴重而使遲滯角更大。

關鍵字

石英 ； 接觸角 ； 奈米結構 ； 潤濕性

並列摘要

Quartz has been widely used in mechanical structures, optic components and oscillators because of its superb properties in thermal stability, light transmission, insulation, and piezoelectricity. With the development of MEMS technology, quartz also becomes an important MEMS material. The surface wettability plays an important role in chemical detecting microsystems and biomedical components. One of the effective ways to modify the surface wettability is by introducing micro/nanostructures on the surface. In this study, we use thermal annealing process to make the platinum nano-dots and use it as the etching mask. Then, we use ammonium bifluoride solution to etch the quartz wafer and obtain the nanoneedle structures on the surface. The surface morphology is observed by SEM. Then, we measure the static and dynamic contact angles and compared with theoretical models.
In the results, as the thickness of the platinum film increases, the diameter of nano-dots increases and the density of nano-dots decreases. The nano-dots can withstand the etchant although it has poor adhesion. By using different size and density nano-dots with different time, various height and density nanostructures are obtained. In the contact angle measurements, it suggests that the droplet penetrates into the structures and partially contacts the bottoms of them. Compared with the theoretical models, we find that the ratio of the bottom contacting area decreases with the increase of the structure density. And the decreasing level increases with the increase of the structure height. The dynamic contact angle measurements show that the structure has great impact on the hysteresis behavior. This situation can be explained by the droplet penetration into the structures, which impede the move of the droplet. The hysteresis increases with the increase of surface roughness. The situation becomes severe when the droplets partially touch the bottom surface

並列關鍵字

quartz ； contact angle ； nanostructure ； wettability

參考文獻

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