Thermodynamic Analysis of Chemical Vapor Deposition of BN + AIN Composite Coatings

Thermodynamic calculations were performed using a modified solgasmix‐pv computer program in order to study the feasibility of codepositing boron nitride (BN) plus aluminum nitride (AIN) by chemical vapor deposition. Reactants considered were AICl 3 , BCl 3 or B 2 H 6 , NH 3 , and H 2 . Deposition diagrams were generated for the BCl 3 ‐AICl 3 ‐NH 3 system over a range of processing conditions such as temperature, total system pressure, and reagent concentrations. Codeposition of BN + AIN was predicted by the calculations for temperatures in the range of 900 to 1700 K and pressures of 10.13 to 101.3 kPa. The predicted deposition efficiency at equilibrium was much higher for BN than for AlN at most reagent compositions. The AlN deposition efficiency increased with decreasing temperature and decreasing BCl 3 content, with increasing NH 3 content, or with the addition of H 2 . Aluminum chlorides were found to be the dominant gaseous species.