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Study on Initial Stage of Oxidation of Hydrogen-Terminated Silicon Surface and Structure of Interface between Ultra-thin Metal Film and Ultra-thin Silicon Oxide Film

氢封端硅表面氧化初期及超薄金属膜与超薄氧化硅膜界面结构的研究

基本信息

批准号：
04452096
负责人：
HATTORI Takeo
金额：
$ 4.42万
依托单位：
Musashi Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

In order to form high quality silicon oxide and SiO_2/Si interface in atomic scale, it is important to prepare ultra-clean and atomically flat Si surface. Namely, in the case of Si(111) surface it can be realized by the treatment in 40% NH_4F solution, while in the case of Si(100) surface it can be realized by the epitaxial growth of Si in hydrogen gas at 1100ﾟC.In either case Si surface is terminated with hydrogen and is atomically flat. Because hydrogen-terminated Si surface is chemically stable, the passivation of Si surface with native oxide is expected to be replaced by that with hydrogen. In the present study initial stage of oxidation of atomically flat hydrogen-terminated Si(111) in 1 Torr dry oxygen at 300ﾟC was studied in details by X-ray photoelectron spectroscopy. By comparing this experimtal results with simulated results of oxidation process, it was found that the oxidation proceeds non-uniformly and layr by layr growth of oxide proceeds locally. However, if the oxidation is performed in 1 Torr dry oxygen at 600 and 800ﾟC through 0.5 nm thick oxide formed in 1 Torr dry oxygen at 300ﾟC, the periodic changes in interface structure appeared with the progress of oxidation. This can be understood by the layr by layr growth of thermal oxide. These results can be understood such that below the critical thickness of 0.5-0.8 nm oxidation proceeds non-uniformly, while above this critical thickness the atomic steps at the interface flow uniformly to result in layr by layr growth of thermal oxide. In order to confirm this important discovery, only a little time could be spent for the formation of metal /Si interface and the measurement of valence band spectra of this system. By the way it was found from the study on the initial stage of oxidation in 1 Torr dry oxygen at 200, 300 and 400ﾟC that the oxidation proceeds more uniformly at lower oxidation temperature.

为了在原子尺度上形成高质量的氧化硅和SiO_2/Si界面，制备超洁净、原子级平整的Si表面至关重要。Si（111）表面的外延生长可以通过在40%NH_4F溶液中处理来实现，而Si（100）表面的外延生长可以通过在1100 ℃氢气中外延生长来实现。由于氢封端的硅表面是化学稳定的，与自然氧化物的硅表面的钝化，预计将被取代的氢。本文用X射线光电子能谱详细研究了原子级平坦的氢封端的Si（111）在300 ℃、1 Torr的干氧中氧化的初始阶段。将实验结果与氧化过程模拟结果进行比较，发现氧化过程是不均匀的，氧化层是局部逐层生长的。然而，如果在600和800 ℃下在1 Torr干燥氧气中通过在300 ℃下在1 Torr干燥氧气中形成的0.5nm厚的氧化物进行氧化，则随着氧化的进行出现界面结构的周期性变化。这可以通过热氧化物的逐层生长来理解。这些结果可以理解为，在0.5- 0.8nm的临界厚度以下，氧化不均匀地进行，而在该临界厚度以上，界面处的原子台阶均匀地流动，导致热氧化物的逐层生长。为了证实这一重要发现，只需花费很少的时间就可以形成金属/Si界面并测量该体系的价带谱。顺便说一下，从在200、300和400 ℃下在1 Torr干燥氧气中氧化的初始阶段的研究中发现，在较低的氧化温度下氧化进行得更均匀。