Thermodynamic Aspects of Diamond/β‐SiC Composite Films

Abstract

A thermodynamic equilibrium analysis involving H 2 -CH 4 -Si(CH 3 ) 4 (tetramethylsilane, TMS) gas mixtures is made to understand the evolution of major gas-phase species and to predict the solid-phase co-deposition of diamond and b-SiC phases. The equilibrium compositions are analyzed at the practical deposition conditions of nanocrystalline diamond/b-SiC composite films. The influence of various predominant species on the equilibrium compositions is investigated.

Thermodynamics of the Production of Condensed Phases in the CVD of Methyltrichlorosilane Pyrolysis

“…[11,60,66] Consequently, the temperature region for the co-deposition of C and SiC should be where the maximum C is located in the case where a higher C content material is desirable. [29,55] In the higher temperature region (>1300 K for 0.6 kPa, >1400 K for 6 kPa, and >1500 K for both 60 and 100 kPa), the amount of b-SiC slightly decreases (i.e., 0.99 to 0.78 mol for 0.6 kPa, 0.98 to 0.85 mol for 6 kPa, 0.96 to 0.86 mol for 60 kPa, or 0.95 to 0.87 mol for 100 kPa) whereas the amount of the co-deposited C increases (i.e., 0.011 to 0.20 mol for 0.6 kPa, 0.020 to 0.14 mol for 6 kPa, 0.041 to 0.11 mol for 60 kPa, or 0.038 to 0.092 mol for 100 kPa). The results show that the main product is still b-SiC, but the minor product is the co-deposited C. This is in excellent accord with the experimental observations of Lim et al [55] [i.e., the amount of SiC decreases and that of free carbon increases with increasing temperatures (higher than 1050 8C)].…”

“…[74] Since a large number of short-lived radicals or highly reactive intermediates (the experimental data of which are temporarily unavailable) must be produced and may also play important roles in the equilibrium system, a theoretical study involving as many species as possible is desirable. As the main features of the co-deposition of the solid phases as a function of the experimental parameters of the process are already known, [11,[20][21][22][23][24][25][26][27][28][29]43,[57][58][59][60][61][62][63][64][65][66][67][68][69][70][71] an optimization and application of a new database is another main motivation for our work. For these reasons, we carried out thermodynamic data evaluations in the H 2 /MTS system [75][76][77][78][79][80][81] with accurate model chemistry methods.…”

Diamond/β-SiC Composite Thin Films: Preparation, Properties and Applications

“…The co-deposition of diamond and β-SiC phases was predicted to be possible by the addition of tetramethylsilane (TMS) during the diamond growth [2]. However, it is only possible in a narrow temperature region.…”

“…The feasibility of the fabrication of diamond/β-SiC composite films was revealed via a simple thermal dynamic calculation [2]. The co-deposition of diamond and β-SiC phases was predicted to be possible by the addition of tetramethylsilane (TMS) during the diamond growth [2].…”