Two-dimensional computational fluid dynamics modeling of slip-flow heat transfer in the hot filament chemical vapor deposition process

The computational fluid dynamics (CFD) modeling on the hot filament chemical vapor deposition (HFCVD) process used to produce a diamond film has been conducted to anticipate the heat transfer and calculate the generation of H. The effect in the slip-flow regime owing to the low-pressure process should be considered to simulate the heat transfer accurately. In addition, a heterogeneous reaction occurring on the filament should be included to calculate the generation of H. The parameters to simulate such microscopic phenomena were applied in the present work and validated by comparing the results with the previous work. The thermal accommodation coefficient (TAC) for H2 was determined as 0.3, at which the calculated mass fraction and H concentration showed good agreement. In addition, It was confirmed that the value could be applied over various filament temperatures and operating pressure. Further, the behavior of H is analyzed above the substrate; the analysis results indicate that there is a correlation between the gas temperature and the gradient of H concentration on the substrate. The high gas temperature caused a severe gradient; thus, a non-uniform film may be deposited. The developed modeling method suggested that microscopic phenomena could be simulated without experimental materials. This fact implied that it is possible to anticipate the temperature and H concentration regardless of the structural design.