濕度對沾筆式奈米印刷術之應用

Abstract

本文利用原子力學顯微鏡(Atomic Force Microscope，AFM)研究沾筆式奈米印刷技術(Dip-pen Nanolithography，DPN)，並探討原子力學顯微鏡上，針尖上的墨水沾附在基板上的機制，文中選用兩種不同特性的分子作為奈米圖形化的研究，分別為MHA(16-mercaptohexadecanoic acid)以及ODT(1-octadecanethiol)；兩者最大的不同點為，MHA是具有親水性的官能基，而ODT是具有疏水性的官能基。藉由改變相對濕度來觀察親水性和疏水性官能基在金表面上的吸附，並且瞭解這兩種分子在金表面的擴散程度；另外，將兩種不同官能基的分子混合，並且沈積到金表面上，進一步觀察親水性和疏水性官能基對於金基材表面的擴散情形。 實驗結果顯示，親水性MHA分子會因為相對濕度的改變有很大的變化，疏水性ODT分子在環境相對濕度的改變下影響不大；MHA和ODT混合的墨水在基板上的擴散情形，會因為分子不同的特性造成親水性分子聚集在中央，疏水性的分子則擴散在親水性分子周圍；改變混合分子的相對濕度，發現相對濕度高的情況下，親水性分子的擴散速率遠大於疏水性分子，這更進一步證明環境的改變對於親水性分子的影響遠大於疏水性分子。In this thesis, we report the studies of the dip-pen nanolithography (DPN) technology using atomic force microscope (AFM) and linking mechanisms of 16-mercaptohexadecanoic acid (MHA) and 1-octadecanethiol (ODT) on the Au substrate. The diffusion and adsorption behaviors of the hydrophilic (MHA) and hydrophobic (ODT) functional groups on Au substrate under various relative humidity conditions were studied. In addition, we also examined the diffusion and adsorption of the binary alkanethiol mixture of MHA and ODT.

We found that the diffusion of the hydrophilic MHA molecule was highly dependent on the relative humidity; a similar observation for hydrophobic ODT molecule was not made. A phase separation occurred in the binary alkanethiol mixture of MHA and ODT, in which the hydrophilic MHA tended to form patterned structure surrounded by the hydrophobic ODT. The phenomenon found contrasts to the bulk behavior of such adsorbates. Furthermore, in the binary alkanethiol mixture system, we also found that the MHA diffusion rate was significantly larger then that of ODT after increasing the relative humidity. Thus, we conclude that the hydrophilic molecule possesses a significant higher sensitivity to relative humidity compared with hydrophobic molecule.