銅金合金及核殼奈米粒子之合成、氧化特性及其奈米導線之研究

Abstract

奈米級 Cu:Au 二元金屬系統氧化行為之研究，無論對奈米氧化理論之修正或是奈米 科技之應用均是極為重要的一環。然至目前為止，不同成份比例(atomic ratio)之Cu-Au 合金(alloy)奈米粒子抑或是Cu/Au 核殼(core-shell)奈米粒子至今仍尚未被系統化的製備 以及研究。 本研究計畫第一年擬利用液相化學還原製程，研製一系列不同Au 含量之Cu-Au 合 金奈米粒子及不同Au 殼層厚度之Cu/Au 核殼奈米粒子。合成所得之奈米粒子，主要利 用X 光繞射(XRD)、高分解能電子顯微鏡(HREM)、電子能譜儀(XPS)及相關理論計算， 評估奈米粒子合成初始之結構，包括(1) Cu-Au 合金固溶狀態以及(2) Cu/Au 核殼之包覆 狀態。並藉由定性及定量分析Cu 氧化物是否存在亦或形成量，來探討結構因素(合金及 核殼)及成份因素(Au 含量)對Cu 奈米氧化特性之影響。 研究計畫第二年主要將所製備且已經過結構鑑定確認之 Cu-Au 合金奈米粒子及 Cu/Au 核殼奈米粒子溶液，以旋轉塗佈法(spin coating)將粒子塗佈至以電子束微影蝕刻 法所製備之奈米直線溝槽中(SiO2 基板)，再於不同氣氛之下，進行中低溫燒結(<300oC)。 燒結完成之試片將再以XPS 確認其氧化態，燒結後粒子結構則由XRD 及SEM 進行確 認，最後並利用四點探針法來進行導電度之測試。本階段將探討燒結過程中，奈米粒子 結構變化與Cu 價態變化之外，並進一步探究燒結結構與導電度之關係。

Oxidation of nano-scaled Cu:Au bimetallic system is of great importance for both theoretical and practical purposes. However, till now Cu-Au alloyed nanoparticles or Cu/Au core-shell nanoparticles have not been systematically synthesized and investigated yet. Further research is therefore needed. In the first year of the research plane, Cu-Au alloyed nanoparticles with various Au contents and Cu/Au core-shell nanoparticles with various Au shell thickness will be generated by direct chemical reduction method. In this stage, x-ray diffraction (XRD), high-resolution electron microscope (HREM), and x-ray photoelectron spectroscopy (XPS) will be mainly used to identify the Cu-Au alloyed uniformity as well as the coverage condition of Au shells of the generated nanoparticles. In addition, with precise measurement and theoretical calculation, the oxide species, e.g. Cu2O and CuO, and amounts can be characterized qualitatively and quantitatively. In the second year, using the spin-coating method, the well identified nanoparticles will be spread into nano-scaled channels made by lithography and etching method on SiO2/Si wafer surface. We plan to investigate the sintering process of the Cu-Au alloyed nanoparticles and Cu/Au core-shell nanoparticles under different temperatures (from 25 oC up to 300oC) with various oxygen pressures. The structural parameters including sintered structure and oxidation condition will be checked again for the comparison with the initial structures before sintering. The electrical conductivity of the sintered nanoparticles will be measured by 4-probe method. This study is expected to understand the potential of Au-Cu alloyed nanoparticles and Cu/Au core-shell nanoparticles for electrical applications such as nano-conductive wires and devices.