Modeling studies of the chemical vapor deposition of boron films from B2H6

The effect of growth conditions on the chemical vapor deposition of boron thin films from diborane (B2H6) was investigated using a combination of experimental studies and computational fluid dynamics-based reactor modeling. A multi-physics computational model was developed to simulate the thermal-fluid environment in the reactor. The proposed chemistry model incorporated into the simulations includes gas-phase decomposition and formation of B2H6 and surface adsorption and reaction of borane (BH3). The model accurately predicts the experimentally measured temperature and partial pressure dependence of the boron growth rate using the sticking coefficient of BH3 on the growth surface as the only adjustable parameter in the calculations. The results indicate that at lower growth temperatures (<500°C) the boron growth rate is limited by gas-phase kinetics while at higher temperatures (>500°C) the growth rate is limited by mass transfer of BH3 to the substrate surface. The studies of boron thin film growth are relevant to the deposition of superconducting MgB2 thin films, in which B2H6 is used as the boron precursor.