| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 96 === Self-assembled monolayers (SAMs) can behave as negative or positive resist after irradiated by physical sources such as X-ray, electron beam or ion beam. As well, the electron beam irradiated SAMs can thereafter promote exchange reactions with other SAMs molecules. In addition to the mentioned physical sources, the downstream microwave plasma can provide an alternative method to modify SAMs. In this study, we applied the downstream microwave nitrogen plasma for the modification of the octadecanethiol (ODT) SAMs chemically adsorbed on Au. The ODT/Au was masked by Au mesh and patterned by the exposure of plasma. The patterned ODT/Au was then developed by Au etching process. Subsequently the plasma-exposed ODT/Au was particularly examined by the molecular exchange reaction with Mercapto-undecanoic acid (MUA) in ethanol. The exchange reaction on the plasma-exposed ODT/Au was distinguished by the presence of newly formed S-Au bonds and the COOH tail group from MUA. Synchrotron-based high resolution X-ray photoemission spectroscopy and scanning photoelectron microscopy were applied to characterize the surfaces prepared in different stages. Two topics were discussed: a possible mechanism that formed a negative or positive resist and an extent of subsequent exchange reaction on the plasma-exposed ODT/Au. Experimental results demonstrated that by controlling the plasma exposure time, the modified ODT/Au was competent to behave as negative or positive resist. The most probable process is related to the oxidization or molecular desorption (i.e. with the tail group, alkyl chains, and the head group) that tends to damage SAMs structure adsorbed on Au as well as cross-linking among alkyl chains (i.e. with a significant amount of lasting S-Au bonds) that tends to enhance the molecular configuration. The plasma-exposed ODT molecules on Au could also be desorbed and exchanged by MUA. Based on these findings, it is promising to apply the plasma-patterned SAMs combined with the molecular exchange reaction for making the variety of micro/nano devices such as micro-fluid channels and micro-scale bio-chip.
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