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

利用薄管化学气相沉积反应器，在1010℃和50Torr的条件下进行了热解碳的化学气相沉积。对甲烷、乙烷、乙烯、乙炔、丙烷、丙烯、正丁烷、苯等进行了沉积实验，考察了各种碳氢化合物在气相中复杂反应生成的影响。获得了热解碳样品，并用微量气相色谱仪分析了产物的气体组成。由丙烷制备的样品的XPS测量表明，sp3C-C键的比例约为70%，并检测到少量的sp2C-C键。以丙烯为原料制得的样品的sp3含量为30%。丙二烯样品的sp^3含量为15%。X射线衍射和拉曼散射测量表明，每个样品似乎都是非晶态的。而在由苯、烯和烯制备的热解碳样品中，通过透射电子显微镜观察到层状结构。产物气体分析表明，丙二烯…当丙烷进料到反应器中时，气相中的烯丙基含量仍能达到约5%。由丙烷制备的薄膜中观察到的sp2结构的来源被认为是气相中形成的烯丙烯和烯丙烯。气相中的膜前驱体似乎决定了所得膜的结构。利用基元反应数据库对气相反应进行了数值模拟。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目的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。根据数值模拟和气体成分分析的结果，从651个与丙烷裂解有关的基元反应中提取了26个重要反应。推导出的简化模型与实验结果吻合较好。较少

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