快速热氧化制备超薄GeO_2及其性质

Growth and Properties of Ultra Thin GeO_2 by Rapid Thermal Oxidation

超薄氧化锗对钝化Ge MOSFET器件中高介电常数栅介质与Ge界面具有重要的意义。通过研究400～550℃下快速热氧化锗制备氧化锗的过程及其性质,发现在一定温度下较短的氧化时间内,氧化锗的厚度随氧化时间的增加呈明显的两段线性关系。在开始阶段,氧化锗具有高的生长速率;当氧化锗厚度达到一定值(与温度相关)时,氧化速率变慢,与Deal-Grove氧化模型中的线性生长速率基本一致。X射线光电子能谱(XPS)测试结果表明氧化锗中存在不同价态的Ge,且随着氧化时间的增加,氧化锗的氧化程度逐渐提高。在550℃下氧化180 s形成的氧化锗用于Ge-MOS结构,C-V特性表明在禁带中央处获得了较小的界面态密度,达到1.7×1012 cm-2eV-1。

It was demonstrated that the ultra thin germanium oxide was effective to passivate the high-k dielectric/Ge interface for fabrication of high performance germanium MOSFET. The properties of the ultra thin germanium oxide formed by rapid thermal oxidation were investigated which were in temperature range from 400 ℃ to 550 ℃. The two distinct linear relationships between germanium oxide thickness and oxidation time are observed during the initial oxidation of Ge. At the very beginning, the oxidation rate is very high, which is reduced significantly when the oxide thickness reaches a certain value （depending on oxidation temperature）. The slower oxidation rate on the later stage is in fair agreement with the prediction of Deal-Grove model. The X-ray photoelectron spectra from the germanium oxide reveals that the various of chemical states of Ge exist in the oxide and the degree of oxidation of Ge increases with oxidation time. The capacitance-voltage characteristics of the Ge MOS structure with germanium oxide fabricated at 550 ℃ for 180 s shows small hysteresis and relatively lower interface state density of 1.7 × 10^12 cm^-2eV^-1 at midgap.