Surface reaction process at epitaxial growth of 3C-SiC on Si(001) using organosilicon compounds

本课题的目的是了解以有机硅化合物为原料在Si(001)衬底上外延生长3C-SiC的反应过程，以实现性能优良的碳化硅的低温外延生长。2002年，利用反射高能电子衍射(RHEED)和扫描隧道显微镜(STM)原位观察了二甲基硅烷(DMS)或单甲基硅烷(MMS)在Si(2x1)表面的初始反应过程。用扫描隧道显微镜观察到了Si(2x1)和Sic(4x4)结构。通过线型测量对这两种结构的晶格常数进行了估算，发现c(4x4)域被收缩，而Si(2x1)域被扩展。碳化硅岛不是沿衬底表面的原子台阶成核，而是在平台上成核。此外，原子力显微镜测量表明，碳化硅岛沿&lt；100&gt；方位生长。这一方向与碳原子的位置向c(4x4)次表层扩散相一致。根据这些结果，我们认为碳化硅是在c(4x4)结构域上形成的。2003年，用四极质谱仪鉴定了从反应表面解吸出来的自由基和分子。在MMS(DMS)与Si(2x1)表面反应过程中，几乎没有检测到甲基和硅基，只检测到氢分子。从这些结果来看，甲基和硅基没有从表面解吸，而是分解成C和Si原子。在形成c(4x4)结构的过程中，C原子扩散到衬底中，Si原子补偿二聚体空位，在薄膜生长过程中，两个原子都形成了碳化硅岛状结构。利用质谱仪的程序升温脱附光谱证实了硅双占据二聚体(DOD)在c(4x4)表面的背键中形成了Si-C键。

The objective of this project is to understand the reaction processes during the epitaxial growth of 3C-SiC on Si(001) substrates using organosilicon compounds as source materials in order to realize the low temperature epitaxial growth of SiC with excellent properties.In 2002, the initial reaction process of dimethylsilane(DMS) or monomechylsilane(MMS) on Si (2x1) surface was observed in-situ using reflection high-energy electron diffraction(RHEED) and scanning tunneling microscopy(STM) : On the surface of Si c(4x4) structure, which appears in RHEED pattern during incubation time before SiC nucleation, both Si(2x1) and Si c(4x4) structures were observed by STM measurement. From the evaluation of the lattice constant for the both structures by lineprofile measurement, the c(4x4) domain was contracted and the Si(2x1) domain was expanded. SiC islands were not nucleated along atomic steps of the substrate surface but on the terrace. In addition, the SiC islands were grown along <100> azimuth from AFM measurement. This direction agrees with that the positions of carbon atoms diffused into subsurface layer of c(4x4). From these results, it was considered that the SiC islands were formed on the c(4x4) domain.In 2003, radicals and molecules desorbed from the reaction surface were identified using a quadrupole mass spectrometer. Methyl and silyl groups were hardly detected, and hydrogen molecules were only detected during the reaction between MMS(DMS) and Si(2x1) surface. From these results, methyl and silyl groups do not desorb from the surface but decompose into C and Si atoms. The C atoms diffuse into the substrate and the Si atoms compensate dimer vacancies during the formation of c(4x4) structure, and both atoms are incorporated into SiC islands during film growth. From temperature-programmed desorption spectra using the mass spectrometer, the formation of Si-C bonds in the back bonds of Si double occupied dimers(DOD) was confirmed on the c(4x4) surface.