Atomic scale monitoring for epitaxial growth process of 3C-SiC on Si

本课题旨在了解以甲基硅烷为源材料的3C-SiC在Si衬底上外延生长的反应过程，从而实现性能优异的SiC的低温外延生长。1999年，从低压CVD （LPCVD）和以单甲基硅烷（MMS）为源气的三极管等离子体CVD晶体生长实验中发现，三极管等离子体CVD在900℃下成功实现了外延生长，而LPCVD在高于950℃的温度下成功实现了外延生长。在LPCVD和三极管等离子体CVD中，SiC生长的活化能分别为70kcal/mol和43kcal/mol。2000年，为了研究SiC在Si（001）表面的生长机理，利用反射高能电子衍射（RHEED）原位观察了二甲基硅烷（DMS）与Si （2×1）表面的初始反应过程。将衬底温度提高到650 ~ 750℃，通过DMS供电，在孵育时间延长后，观察到3C-SiC斑点。在孵育期间，观察Si - c（4×4）表面重建。Si c（4×4）重建被认为是碳原子从吸附的DMS分子扩散到Si衬底的结果。根据Arrhenius图计算出Si c（4×4）结构出现前的活化能约为16kcal/mol。认为碳原子吸附DMS分子扩散到Si衬底，形成Si_xC_<1-x>合金是为了在孵育过程中缓解Si和SiC之间的晶格失配。根据碳化硅初始生长速率的Arrhenius图计算得到的活化能约为45kcal/mol。该能量值与硅表面氢的脱附能量值接近。在此温度范围内，吸附在Si表面的DMS分子的氢原子迁移到Si悬空键上，然后从Si- h键上脱附。硅表面的氢脱附过程被认为是一个限速步骤。在此基础上，以二甲基硅烷为源气体，利用LPCVD和三极管等离子体CVD进行了SiC外延生长。SiC生长的活化能为90kcal/mol。另一方面，在三极管等离子体CVD生长SiC时，外延生长的活化能几乎不依赖于源材料，即在MMS和DMS之间。少

The objective of this project is to understand the reaction processes during the epitaxial growth of 3C-SiC on Si substrates using methylsilanes as source materials in order to realize the low temperature epitaxial growth of SiC with excellent properties.In 1999, from the experiments of crystal growth by low-pressure CVD (LPCVD) and triode plasma CVD using monometylsilane (MMS) as a source gas, the epitaxial growth at 900℃ was successful by triode plasma CVD, while the epitaxial growth was successful at higher temperature than 950℃ by LPCVD.The activation energies of SiC growth were 70kcal/mol in LPCVD and 43kcal/mol in triode plasma CVD, respectively.In 2000, to investigate the growth mechanism of SiC on Si (001) surface, the initial reaction process between dimethylsilane (DMS) and Si (2×1) surface was observed in-situ using reflection high-energy electron diffraction (RHEED). By the DMS supply after raising the substrate temperature to 650-750℃, 3C-SiC spots were observed after incu … More bation time. During the incubation time, Si c(4×4) surface reconstruction was observed. The Si c(4×4) reconstruction was considered to have been a result of the carbon atoms diffused to the Si substrate from adsorbed DMS molecules. The activation energy calculated from the Arrhenius plot of the time until the Si c(4×4) structure appeared was about 16kcal/mol. It was considered that the carbon atoms adsorbed DMS molecules diffused into the Si substrate and formed Si_xC_<1-x> alloys in order to relax the lattice mismatch between Si and SiC during incubation time. The activation energy calculated from the Arrhenius plot on the initial growth rate of SiC formation was about 45kcal/mol. This energy value was close to that of hydrogen desorption from Si surface. In this temperature region, hydrogen atoms of DMS molecules adsorbed on Si surface migrated to Si dangling bonds and thereafter desorbed from Si-H bonds. The hydrogen desorption process from Si surface is considered to be rate-limiting step.Parallel to the above investigation, SiC epitaxial growth was carried out by LPCVD and triode plasma CVD using dimethylsilane as source gas. The activation energies for SiC growth were 90kcal/mol in. In the case of the SiC growth by triode plasma CVD, on the other hand, the activation energy for the epitaxial growth hardly depended on the source materials, i. e. between MMS and DMS. Less