High-throughput thermodynamic analysis of the CVD of SiC from the SiCl4-CH4-H2 system

A high-throughput thermodynamic analysis based on the CALPHAD approach is employed in this study to gain insights into the chemical vapor deposition (CVD) of SiC from the SiCl4-CH4-H2 system using up-to-date thermodynamic databases. The explored deposition conditions, i.e., temperature, pressure, C/Si ratios and H2/SiCl4 ratios, ranges from 800 to 1800 °C, 400 to 40,000 Pa, 0.1 to 10 and 0.1 to 200, respectively. In addition to the metrics of deposit purity and deposition efficiency of SiC, a new metric, i.e., the utilization efficiency of precursors, is proposed in this work to facilitate the identification of the optimal deposition conditions. The influence of deposition parameters and precursor compositions on the compositions and phase stabilities of the condensed and gas phases pertinent to vapor processing are elucidated. The results show that the deposit purity is more sensitive to temperature than pressure. The optimal conditions to achieve high deposit purity (100 %), deposition efficiency (99.74 %) and the utilization efficiency of precursors (99.74 %) locate on the C/Si ratios between ~0.8 and ~ 1, H2/SiCl4 ratios above 8, low pressure (below 10 kPa) and medium temperatures (~ 1000 to ~1400 °C). Furthermore, low C/Si ratios (< 0.5) and high C/Si ratios (> 1) lead to the formation of free Si and graphite, respectively.