Thermodynamic analysis of phase and composition during the co-deposition of SiC-HfC films by chemical vapor deposition method

A thorough thermodynamic investigation of phase and composition in the SiCl₄-HfCl₄-C₃H₈-H₂ system is conducted during the co-deposition of SiC + HfC films by chemical vapor deposition method (CVD). The results indicate that medium temperature ranging from 1000 to1400 ^oC is more suitable for SiC deposition, while higher temperature (1400 ∼ 1800 °C) promotes HfC deposition. The co-deposition of pure SiC and HfC phases is observed when the C₃H₈/(SiCl₄ + HfCl₄) ratio is maintained between 0.15 and 0.3, along with an H₂/(SiCl₄ + HfCl₄) ratio exceeding 50. The excess carbon source leads to undesirable formation of graphite, whereas insufficient carburization may result in the formation of impurities such as Si or HfSi₂. An optimal increase the hydrogen ratio can suppress the formation of the graphite phase, but too much hydrogen may cause the decomposition of SiC, leading to additional impurities. Furthermore, a high-throughput calculation method was employed to generate the composition mapping, which allow for fine-tuned control of SiC-HfC film composition by adjusting temperature and the SiCl₄:HfCl₄ ratio.