A THERMODYNAMIC APPROACH TO CHEMICAL-VAPOR-DEPOSITION OF BORON-NITRIDE THIN-FILMS FROM BORAZINE

Thermodynamic analysis of the chemical vapor deposition (CVD) of boron nitride has been performed for the B-N-H system using the method of t he minimization of Gibbs' free energy. The calculations were carried o ut for two gas mixtures with borazine: (1) B3N3H6 + N-2 and (2) B3N3H6 + NH3 for total pressures P-tot of 1 and 10(-2) Torr, temperature ran ge 800-2300 K and for a variety of initial gas mixture compositions. T hree different modifications of boron nitride (hexagonal h-BN, cubic c -BN and wurtzite w-BN) were taken into consideration. It was obtained that c-BN is formed at temperatures up to 1804 K, h-BN modification is most stable above this temperature, w-BN is a metastable phase at all possible variations of process conditions. Mixture borazine with nitr ogen is more promising to deposit h-BN at low pressure.