Simulations of temperature field in HFCVD diamond films over large area

A three-dimensional model was developed to investigate the influence of various hot filaments parameters on substrate temperature fields that significantly affect the nucleation and growth of diamond films over large area by hot-filament chemical vapor deposition (HFCVD). Numerical simulated results indicated that substrate temperature varies as a function of hot filaments number, radius, temperature, emissivity, the distance between filaments, and the distance between substrate and filaments arrangement plane. When these filaments parameters were maintained at the optimal values, the homogeneous substrate temperature region of 76 mm x 76 mm with the temperature fluctuation no more than 5% could be obtained by a 80 mm x 80 mm hot filaments arrangement plane. Furthermore, the homogeneous region could be enlarged to 100 mm x 100 mm under the condition of supplementary hot filaments with appropriate parameters. All of these calculations provided the basis for specially optimizing the hot filaments parameters to deposit uniform diamond films over large area by HFCVD.