Theoretical study of thermochemistry of molecules in the silicon-carbon-chlorine-hydrogn system

Abstract

Ab initio electronic structure calculations coupled with empirical corrections are used to obtain a self-consistent set of heats of formation for molecules in the series CHSiCl, (n, m = 0-3) and for selected molecules in the series (CH3),,SiH,Clp. Heats of formation are also reported for the series Cl$iSiCl, (m, n = 0-3) and for H C e S i C l Z H and H$=CH(SiC12H). Gibbs free energies as a function of temperature and standard entropies are given for all molecules in the study. Heats of formation are used to evaluate potential pathways for the decomposition of C13SiCH3, a common silicon carbide chemical vapor deposition precursor. The analysis includes the calculation of the transition state for the 1,Zelimination of HCl from Cl3SiCH3. Theoretical MethodsThe theoretical methods used in these calculations have been presented in detail el~ewhere.~.'~ A general discussion is provided here, however, for the reader who is not familar with the computational technique.Molecular geometries, vibrational frequencies, and electronic energies were obtained using the Gaussian series of codes developed by Pople et al.I5 The equilibrium molecular geometry was determined using restricted HartreeFock (RHF) theory for closed-shell molecules and unrestricted HartrebFock (UHF).haory for open-shell molecules. A 6-3 1 G* split-valence basis ,e, w:'h polarkation functions on the heavy atoms was used to ''

Thermodynamics Simulations Applied to Gas-Solid Materials Fabrication Processes

“…With coaxial source and substrate, the exchanged flow between the r0 radius source and r1, radius substrate, separated by a distance h is given by the relation (38 The results of the simulations are the same order as the obtained experimental values.…”

“…This is related to the difficulty to measure thermochemical properties of such reactive, short life time, species. Most of the thermodynamic data that have been used for these species come from ab initio electronic structure calculations combined with empiric bond additivity corrections [37,38]. Mass spectrometry measurements have been carried out to estimate the thermodynamic data of the gaseous species Si2C(g), SiC2(g), SiC(g) and the condensed SiC(s) phase [39,40].…”

Thermodynamic and experimental investigations on the growth of thick aluminum nitride layers by high temperature CVD

“…Contrary to thermodynamic prediction, we definitely observed the formation of condensed AlN above 1600 1C. A new further assessment of thermodynamic data on the whole Al-N-H-Cl system at high temperature should be achieved as for the Si-C-H-Cl system [53,[59][60][61]. Fig.…”

Growth kinetics study in halide chemical vapor deposition of SiC

“…Unless otherwise stated, the figures in this paper show the gas phase composition (solid phases are denoted by subscript-'s'). Calculations were performed in two À232.7 [18] steps. Firstly, the reactant gas mixtures in the respective injectors were equilibrated with graphite.…”