- 學位論文
順流式遠端電漿對單層有機金屬表面 反應機制之研究
Chemical Reactions of Downstream Microwave Plasma to the Alkanethiolate Self-Assembled Monolayers on Gold Surface
摘要
低溫電漿處理為高分子表面改質常被考慮的重要技術。依機台的特性、處理參數及氣體電漿產生形式，可使電漿與有機高分子產生聚合、表面化學反應及交錯連結等效應，創造出特殊的、可運用的及具功能性的表面。本研究使用self-assembled monolayers方式將octadecanethiol（C18H37SH, ODT）固定在Au（111）晶面上，以模擬有機長鏈碳結構作為可定義的緻密表面。實驗中，使用功率80W、處理腔室壓力1torr之順流式N2微波電漿處理，研究ODT-Au試片表面受電漿化學誘發之反應。以Langmuir probe量測電子溫度及其電漿（或離子化）密度，並以此參數作為機台調整的標準。另外，亦研究電漿物種中，紫外光波長大於200nm對ODT-Au的影響。電漿處理後的ODT-Au試片使用靜態接觸角及X光光電子能譜儀（XPS）進行表面分析。實驗結果顯示：本實驗所使用之順流式電漿提供到試片處理位置的電漿密度約為 ，電子溫度約為0.46eV，屬低密度電漿。XPS分析得知：本實驗中，使用N2電漿處理後，可使ODT-Au表面產生新的C-N、C-O、C=O、O=C-OH鍵結，這些極性基團驗在表面創造親水性質，使靜態接觸角由120。下降至18。。分析結果顯示：N2電漿帶進O2，在10sec內可對ODT-Au表面進行化學反應；30sec的處理後，C/Au的比例下降，此與電漿對ODT-Au表面產生蝕刻效應有關。經60sec處理後，表面的N、O與C元素鍵結量減少，但C元素量減少趨緩，可能是電漿作用使表面產生交錯連結結構。本實驗使用之電漿，其所產生波長在200nm以上的紫外光，經120sec照射，對ODT-Au基材結構無顯著影響。此結果亦驗證低密度電漿中的紫外光對與ODT-Au表面的化學反應無顯著影響。
並列摘要
Low-temperature plasma processing has been greatly considered as a vital technique for polymer surface modification. According to the characteristic of plasma generation, the applied processing parameters and the type of gas plasma, the organic substrate may arise some effects such as polymerization, superficial chemical reactions and cross-linking and create specific, applicable and functionalized surfaces. This study utilizes self-assembled monolayers of the octadecanethiol (C18H37SH, or ODT) on Au(111) surface to simulate an organic structure with well-packed and long carbon chains. In this experiment, downstream N2 microwave plasma is generated by 80W under 1 torr; plasma-induced chemistries on the ODT/Au surface are studied. Using Langmuir probe, the state of electron temperature and the electron (or ionization) density are statically measured; they provide valuable information to adjust changing condition in practical plasma applications. The effect of UV generated in plasma, for the wavelengths higher than 200nm, to ODT/Au is also evaluated. Water contact angle and X-ray Photoemission Spectroscopy (XPS) measurements are applied for verifying structural modification at surface. Experimental result has indicated that current downstream plasma provides plasma density of ca. or electron temperature of ca. 0.46eV; it is regarded as low-density plasma. Surface analyses by XPS have revealed that after N2 plasma treatment, new chemical bonds such as C-N, C-O, C=O and O=C-OH are formed on the modified ODT/Au surface. These polarizable groups arise a hydrophilic characteristic at surface and decrease water contact angle from 120o to 18o. Analytical result also implies that N2 plasma takes O2 and reacts with ODT/Au within 10sec. After 30sec of plasma treatment, the C/Au ratio decreases, which is correlated with etching effect on the ODT/Au surface. After 60sec of plasma projection onto the ODT/Au surface, all N, O and C elements are decreased, however, relatively small decrease ratio of C is found, which may be directed to the formation of cross-linked structure at surface. Moreover, for introducing UV generated in plasma, wavelengths longer than 200nm and up to 120sec, the ODT/Au structure is insignificantly affected. This consequence has confirmed that UV produced in low-density plasma does not have the capability to provoke chemical reactions with the ODT/Au surface.