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/分子角度阐明硅外延的生长机理，我们取得了以下成果： 1．我们发现，在 Si-GSMBE 中，源气体分子在低温下使用两个位点，在高温下使用四个位点吸附到 Si 表面上。阐明了低温下生长速率活化能的决定机制。 2．与之前的理解相反，首次阐明了从 Si(100) 表面解吸氢可以采取大于 1 的反应级数。反应级数取决于氢化气体的选择和热历史，其变化可以通过表面成对氢原子的浓度来统一解释。3．关于原位掺杂过程中的表面化学，我们首先开发了一种控制磷原子表面覆盖度的新方法，其中我们简单地计算吸附/解吸序列的数量。利用该方法，发现表面P原子对Si外延的作用是抑制吸附过程和抑制氢解吸。更准确地说，后一种效应由两个途径组成：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生长速率的延迟提供了基础。4．为了在 Si 上实现良好的 SiC 异质外延，我们比较了乙炔和单甲基硅烷 (MMS) 吸附的 Si 表面的原子排列。在乙炔吸附表面上，表面碳和基底Si原子之间发生位点交换，而在MMS吸附表面上交换被大大抑制。然后，通过使用MMS，在低至900℃的温度下，无需任何碳化过程，在Si(100)上成功获得了合格的SiC晶体薄膜。明确了SiC外延合格的关键是彻底消除表面氢。