A thermodynamic approach to chemical vapor deposition of boron nitride thin films from borazine

Abstract

Thermodynamic analysis of the chemical vapor deposition (CVD) of boron nitride has been performed for the BNH system using the method of the minimization of Gibbs' free energy. The calculations were carried out for two gas mixtures with borazine: (1) B 3N 3H 6 + N 2 and (2) B 3N 3H 6 + NH 3 for total pressures P tot of 1 and 10 −2 Torr, temperature range 800–2300 K and for a variety of initial gas mixture compositions. Theree 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 nitrogen is more promising to deposit h-BN at low pressure.