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Surface chemistry of hydrogen on Si surfaces

Si 表面氢的表面化学

基本信息

批准号：
09450015
负责人：
SUEMITSU Maki
金额：
$ 9.02万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450015/
关键词：
silicon epitaxy CVD gas-source MBE doping hydrogen desorption silicon carbide silane disilane シリコンホスフィン水素酸化過程アセチレンガスソース MBE 吸着脱離

项目摘要

With an aim of clarifying the growth mechanism of Si epitaxy on atomic/molecular basis, we have achieved the following.1. We found that, in Si-GSMBE, source-gas molecules adsorb onto the Si surface using two sites at low temperatures and four sites at high temperatures. The mechanism that determines the growth-rate activation energy at low temperatures was also clarified.2. It was clarified for the first time that hydrogen desorption from Si(100) surface can take a reaction order that is larger than unity, as opposed to previous understandings. The reaction order depends on the choice of the hydrogenating gas and the thermal history, whose variation is unifiedly accounted for by using a concentration of paired hydrogen atoms on the surface.3. Concerning the surface chemistry during in-situ doping process, we first developed a novel method for controlling the surface coverage of phosphorus atoms, in which we simply count the number of adsorption/desorption sequence. Using the method, the role of surface P atoms on Si epitaxy was found to be suppression of the adsorption process and suppression of the hydrogen desorption. More precisely, the latter effect consists of two channels : increase of the activation energy and the increase of the reaction order. These findings provide basis for understanding the growth-rate retardation during phosphorus doping.4. To achieve good SiC heteroepitaxy on Si, we compared the atomic arrangements of acetylene- and monomethylsilane(MMS)-adsorbed Si surfaces. On acetylene-adsorbed surface, there occurs site exchange between surface carbon and substrate Si atoms, while the exchange is drastically suppressed on MMS-adsorbed surface. By using MMS, then, a qualified crystalline film of SiC was successfully obtained on Si(100), at as low as 900C without any carbonization procedures. It was clarified that complete elimination of surface hydrogen is key to the qualified epitaxy of SiC.

为了从原子/分子的角度阐明硅外延的生长机制，我们取得了以下成果：1.我们发现，在Si-GSMBE中，源气分子在低温时以两个位吸附在硅表面，在高温时以四个位吸附在硅表面。阐明了决定低温下生长速率活化能的机理。首次阐明了氢从Si(100)表面脱附的反应级数可以大于1，这与以前的理解相反。反应级数取决于加氢气体和热历史的选择，其变化可以统一地用表面上成对的氢原子浓度来解释。关于原位掺杂过程中的表面化学，我们首次提出了一种控制磷原子表面覆盖度的新方法，该方法只需计算吸附/脱附序列的数量。利用该方法，发现表面P原子在Si外延中的作用是抑制吸附过程和抑制氢的脱附。更确切地说，后者由两个途径组成：活化能的增加和反应级数的增加。这些发现为理解磷掺杂过程中的生长速度减慢提供了依据。为了在硅上实现良好的碳化硅异质外延，我们比较了乙炔和单甲基硅烷(MMS)吸附在硅表面的原子排列。在乙炔吸附表面，表面碳原子和衬底硅原子之间发生了位置交换，而在MMS吸附表面，这种交换被强烈地抑制。然后利用MMS在Si(100)表面上成功地获得了质量合格的碳化硅薄膜，其温度低至900℃，无需任何碳化过程。阐明了完全消除表面氢是获得合格的碳化硅外延的关键。