SURFACE CHEMISTRY DURING SiC EPITAXIAL GROWTH USING ORGANO-SILANES

SiC是一种很有前途的下一代功率器件材料。本研究旨在阐明有机硅烷外延过程中的表面化学性质，以及开发低温、高质量的SiC外延材料，研究结果如下：(1)有机硅烷法抑制Si向外扩散：使用分子内含有化学稳定的Si- c键的有机硅烷作为源气体，可以大大抑制Si原子从衬底向外扩散。(2) OS-buffer方法的发展：在SiC/Si异质外延中，必须有缓冲中间层来调节SiC薄膜与Si衬底之间20%的晶格失配。以前采用炭化法形成缓冲层。然而，该工艺所需的高温（~ 900℃）会导致Si衬底产生有害的表面粗糙度和空洞。本研究提出了一种新的方法，即os -缓冲法，即用有机硅烷气体代替烃类气体形成缓冲层。结果表明，在600℃下可以生长出合格的缓冲层。(3) OS-GSMBE方法的发展：代替传统SiC外延中使用一对Si源和c源气体，成功地使用单一有机硅烷气体源生长出合格的SiC外延膜。结果表明，生长温度由1100℃降低到900℃。表面氢也被发现对获得合格薄膜是有害的。(4)在Si上获得单畴SiC薄膜：发现电阻加热方法在Si衬底上获得单畴SiC薄膜是有效的。(5)Si生长的建模：通过获得生长速率和生长表面的氢覆盖率作为衬底温度和二硅烷压力的函数，澄清了Si GSMBE的生长动力学。在此基础上，建立了一个新的生长模型，该模型统一地考虑了生长速率的温度依赖性和压力依赖性。少

SiC is a promising material for the next-generation power devices. This research, aiming at clarifying the surface chemistry during SiC epitaxy using organo-silanes as well as developing a low-temperature, high-quality SiC epitaxy, has yielded the following results.(1) Suppression of Si out-diffusion by using Organo-Silane method: By using an organo-silane as the source gas, which contains a chemically stable Si-C bond within the molecule, the out-diffusion of the Si atoms from the substrate was found to be greatly suppressed.(2) Development of OS-buffer method: In SiC/Si heteroepitaxy, a buffer interlayer is a must to moderate the 20% lattice mismatch between the SiC film and the Si substrate. Formerly, the buffer layer was formed with the carbonization method. The high temperature (〜900℃) required in the process, however, caused harmful surface roughness and voids in the Si substrates. In this study, a new method, named OS-buffer method, has been developed, in which organo-silane gas … More es are used to form the buffer layer in place of hydrocarbon gases. As a result, qualified bufferlayers can be grown at 600℃.(3) Development of OS-GSMBE method: Instead of using a pair of Si- and C-source gases as in the conventional SiC epitaxy, a single source of organo-silane gas was successfully used to grow qualified SiC epitaxial films. As a result, the growth temperature could be reduced from the former 1100℃ to 900℃. Surface hydrogen was also found to be harmful in obtaining qualified films.(4) Obtaining a single-domain SiC film on Si: The resistive heating method was found to be effective in obtaining a single-domain SiC film on Si substrates(5) Modeling of the Si growth: By obtaining the growth rate and the hydrogen coverage at the growing surface as a function of both the substrate temperature and the disilane pressure, the growth kinetics for the Si GSMBE has been clarified. Based on the result, a new growth model has been developed, which accounts for both the temperature- and the pressure-dependence of the growth rate unifiedly. Less