Film precursors and growth mechanisms of carbon and silicon carbide deposition from gas phase

在1010℃、50 Torr条件下，用薄管式CVD反应器进行了热解碳的化学气相沉积。为了研究气相中复杂反应生成的各种碳氢化合物的影响，进行了甲烷、乙烷、乙烯、乙炔、丙烷、丙烯、丙二烯、烯丙基、正丁烷、苯等的沉积实验。采用微型气相色谱仪分析了热解炭的气体组成。XPS测试结果表明，由丙烷制得的样品中sp^3 C-C键的含量约为100%，而由丙烷制得的样品中sp^3 C-C键的含量约为100%. 70%和很少sp^2 C-C键检测。由丙烯制备的样品具有30%的sp^3分数。来自丙二烯的样品中sp^3的含量为15%。X射线衍射和拉曼散射测量显示每个样品似乎是非结晶的。然而，在由苯、丙二烯和烯丙基制备的热解碳样品中，通过TEM观察到层状结构。产品气体分析表明， ...更多信息 气相中的烯丙基分数能够达到约10%。5%，甚至当丙烷进料到反应器中时。在由丙烷制备的膜中观察到的sp^2结构的起源被认为是在气相中形成的丙二烯和烯丙基。气相中的膜前体似乎决定了所得膜的结构。气相反应的数值模拟也进行了使用基元反应数据库。提出了一种将由数百个基元反应组成的反应模型简化为可用于设计的化学反应工程模型的方法。在所提出的方法中，首先通过比较实际气体组成的反应速率来筛选基元反应，然后从化学反应工程的角度进行模型简化。根据数值模拟和实验气体组成分析的结果，从651个丙烷热解基元反应中提取出26个重要反应。推导的简化模型与实验结果相关良好。少

Chemical vapor deposition of pyrolytic carbon was carried out by using a thin tubular CVD reactor at 1010℃ and 50 Torr. In order to investigate the effects of various hydrocarbons formed by complex reactions in the gas phase, deposition experiments from methane, ethane, ethylene, acetylene, propane, propylene, allene, allylene, n-butane, benzene, etc. were conducted. Pyrolytic carbon samples were obtained and the product gas composition was analyzed by micro gas chromatograph. XPS measurement of the sample prepared from propane showed that the sp^3 C-C bond fraction was ca. 70% and few sp^2 C-C bonds were detected. The sample prepared from propylene had a sp^3 fraction of 30%. The sample from allene had a sp^3 fraction of 15%. X-ray diffraction and Raman scattering measurements showed each sample seemed non-crystalline. However, a layered structure was observed by TEM in the pyrolytic carbon samples prepared from benzene, allene, and allylene. The product gas analysis showed the allene … More and allylene fraction in the gas phase was able to reach ca. 5% even when propane was fed to the reactor. The origin of the sp^2 structure observed in the film prepared from propane was thought to be allene and allylene formed in the gas phase. Film precursors in the gas phase seem to determine the structure of the resulting film. Numerical simulation of the gas phase reactions was also carried out by using an elementary reaction database. A procedure to reduce a reaction model consisting of hundreds of elementary reactions to a chemical reaction engineering model that can be used for design purpose was proposed. In the proposed procedure, elementary reactions were first screened by comparing the reaction rates for an actual gas composition, and then the model reduction was made from chemical reaction engineering point of view. From the results of the numerical simulation and gas composition analysis in the experiments, 26 important reactions were extracted from 651 elementary reactions concerning propane pyrolysis. The derived reduced model and the experimental results correlated well. Less