Oxidation mechanism of thin Cu films: A gateway towards the formation of single oxide phase
Oxidation mechanism of thin Cu films: A gateway towards the formation of single oxide phase
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DOI：
10.1063/1.5028407
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发表时间：
2018-05-01
期刊：
影响因子：
1.6
通讯作者：
Gangopadhyay, Subhashis
中科院分区：
文献类型：
--
作者：
Choudhary, Sumita;Sarma, J. V. N.;Gangopadhyay, Subhashis
研究了在相对较低的温度（高达500摄氏度）下薄铜膜的受控热氧化，导致形成单一相的氧化铜，其中氧化温度、持续时间、氧分压、膜厚度和晶体取向对显著控制氧化铜的最终相起非常关键的作用。利用真空辅助热蒸发技术在玻璃和硅衬底上沉积了厚度为100-1000 nm的薄Cu膜。这些Cu膜的氧化在不同的温度下进行可变的持续时间在空气环境以及氧气环境条件。采用四探针电阻率测量、X射线衍射（XRD）、拉曼光谱、紫外-可见（UV-Vis）光谱、扫描电子显微镜（SEM）和X射线光电子能谱（XPS）等技术对氧化膜进行了表征。在热力学平衡下，已经观察到氧化物相仅由氧化温度决定，然而，氧分压可以显著改变该温度范围。在空气中热氧化的情况下，铜膜的初始氧化开始于约150 ℃，但仅在高于200 ℃时观察到氧化亚铜（Cu 2 O）的良好有序的结晶相。然而，氧化铜（CuO）相仅在320摄氏度以上开始出现。铜膜的氧化机理的细节解释与可能的示意性模型的热扩散以及化学反应。(C)2018年作者。
Controlled thermal oxidations of thin copper films at relatively lower temperatures (up to 500 degrees C) leading towards the formation of a single phase of copper oxide are investigated where the oxidation temperature, duration, oxygen partial pressure, film thickness and the crystallographic orientations play very crucial roles to significantly control the final phase of the copper oxide. Thin Cu films of thicknesses 100-1000 nm were deposited on glass and silicon substrates using the vacuum assisted thermal evaporation technique. Oxidations of those Cu films were performed at different temperatures for variable durations in air ambient as well as oxygen ambient conditions. Four probe resistivity measurement, x-ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM) and x-ray photoemission spectroscopy (XPS) techniques have been used to characterize the oxide films. At a thermodynamic equilibrium, it has been observed that the oxide phase is solely determined by the oxidation temperature, however, the oxygen partial pressure can significantly alter this temperature range. In case of thermal oxidation in air, the initial oxidation of the copper films starts at about 150 degrees C, but a well ordered crystalline phase of the cuprous oxide (Cu2O) is observed only above 200 degrees C. However, the cupric oxide (CuO) phase starts to appear only above 320 degrees C. The details of the oxidation mechanism of the Cu film are explained with a probable schematic model in terms of thermal diffusion as well as the chemical reactivity. (C) 2018 Author(s).