Stéphanie de Persis

Gas-phase kinetics analysis and reduction of large reaction mechanisms exemplified in the case of SiC deposition

Abstract Chemical vapor deposition (CVD) is commonly used to grow epitaxial SiC layers at relatively high temperature from SiH 4 –C 3 H 8 –H 2 mixtures. In order to model the deposition process, the kinetics of the gas-phase reactions involved must be known accurately and the main reaction pathways must be identified. For this purpose, we have selected the most recent sets of reactions and related kinetic data available for the C–H and Si–H chemical systems. However, the full mechanism so obtained is too large to be included in a CVD reactor model, because of the computational time required for the calculations and numerical convergence problems. As a consequence, the full mechanism has been reduced using the so-called ‘redundant species and reactions’ method due to Turanyi. Since reactions between Si–H species and C–H species have not been considered, the C–H and Si–H mechanisms have been reduced separately. As a result, a smaller subset of reactions and species describing accurately the gas-phase reactivity in the Si–C–H system has been obtained.

Classical and Dynamic Analysis of Gas Phase Reactivity Influence of Carbon Precursor in the CVD of SiC

The intrinsic low dimensional manifold method (ILDM), which is a reduction method of large gaseous chemical systems, is applied to the gas-phase chemistry used to deposit 4H or 6H silicon carbide (SiC). The 1-dimensional (1-D) manifold corresponding to the relaxation of all the fast reaction modes of the complex gaseous chemical system is calculated and represented according to different projections in the state space. The ILDM method is also used to compare trajectories corresponding to various initial gas-phase compositions. These initial gas-phase mixtures, which include different carbon precursors, all converge towards the same thermodynamic equilibrium. Long before thermodynamic equilibrium is reached, the trajectories are attracted by the 1-D manifold.