長碳鏈的烷基硫醇分子在金的表面上形成自我聚集單分子層（SAM）由於碳氫練間的凡得瓦力與Au-S間的強鍵結，使得其具有排列緻密的特性。本實驗欲將以C10H21SH所形成之自我聚集單分子層自金基材上去除，以利金基材之回收再利用，達到降低成本的目的。利用乾式（O2 Plasma）及濕式（SOCl2、Piranha solution）氧化法進行表面氧化，探討不同氧化法及不同氧化條件如電漿功率、氧化劑濃度、反應時間等對表面上自我聚集單分子層之清除的效果。
由靜態接觸角之結果來測量，以各種氧化法反應所得表面大多呈現親水性，表現出氧化的特性，並藉由X光-光電子光譜儀(XPS或ESCA) 之C1S、O1s及S2P 圖譜及At%結果對各氧化法所產生之表面反應進行分析，發現表面自我聚集單分子層經氧化後皆產生C-C、C-H、Au-S斷鍵及氧化物C-O、C＝O、O-C＝O及RSO3之生成，使烷基鏈降解及部分SAM自基材上移除。經氧電漿反應所得之表面氧化程度高但其所生成氧化物之鑲嵌現象及表面接枝使得整個膜厚隨反應時間及反應功率增加而增加，更加妨礙SAM之清除；而SOCl2系列之組合反應結果產生結構之氧化、部分烷基鏈降解及部分Au-S鍵斷裂，但整體清除效果不佳；至於以Piranha solution反應烷基鏈降解程度最高，Au-S鍵斷鍵情形最劇。遂以S2P結果來判定經Piranha solution反應後表面自我聚集單分子層之氧化清除效果最佳，以反應20分鐘為最明顯。

The self-assembled monolayer (SAM) formed by the long chain alkanethiol has densely-packed, and well-oriented characteristics due to the Van der Waals force between the hydrocarbon chains as well as strong binding between sulfur and gold substrate. The aim of this study is to explore the efficacy of various surface oxidation techniques to remove the self-assembled monolayers formed by C10H21SH on the gold substrate with an attempt to reuse gold substrate that in turns, lowering the cost. The surface oxidation methods explored include O2 plasma treatment and wet chemical oxidations techniques by SOCl2 and Piranha solution. The effect of various processing parameters, such as O2 plasma power, gas pressure, plasma treatment time, and concentration and reaction duration of the wet chemicals on the removal of SAM from gold substrate were evaluated by static contact angle method and x-ray photoelectron spectroscopy (XPS) technique.
Based on the static contact angle results, the surface properties of SAMs were varied markedly, from hydrophobic surface to hydrophilic one, after various oxidation treatments. This can be attributed to the formation of different oxygen-containing hydrocarbons as well as the gold oxide on these post-treated substrates. XPS data indicated the alkanethiol molecules on the pristine SAM can undergo a series of chain scission reactions that occurs along the backbone as well as the formation of the new oxygen containing (i.e. C-O, C=O, O-C=O, RSO3) hydrocarbons on these surfaces. In addition, the deosrption of oxidized/degraded hydrocarbons as well as the bond breaking of Au-S were also noted in XPS analysis. These results indicated that although SAM was oxidized substantially by the O2 plasma treatment, the thickness of the film were increased with plasma power and reaction time as a result of oxygen-containing hydrocarbons inlaying and grafting of hydrocarbon contaminants, which unfortunately retarded the removal of SAM even more. For SOCl2 system, the effects of surface oxidation, adsorbed molecule degradation and thiolate bond breakage were of limited. In contrast, not only the degradation of the adsorbed alkanethiols but also the bond breakage of thiolates were increased drastically by using Piranha solution. Piranha solution had the higher efficacy in removal of SAM, especially for the 20 min treatment time, than any other two methods based on S2p results by XPS analysis

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