CHEMICAL VAPOR-DEPOSITION OF BORON-NITRIDE

Thermodynamics and kinetics of boron nitride deposition from BCl3-NH3 gas mixtures were studied in the temperature range 850 to 1050-degrees-C at pressures between 1.1 and 3.5 Torr. A wide range of deposition rates, as high as 1 mum/min, were measured. The rate of depositon was controlled by an interface reaction with an activation energy of 35 +/- 3 kcal/mol. The deposition rate constant essentially was independent of the partial pressure of NH3 and showed a close to first-order dependence on the partial pressure of BCl3. The rate-limiting step of the interface reaction may be the dissociative adsorption of BCl3 onto the substrate surface. The deposited BN was of theoretical density, turbostratic structure, and contained about 12 atomic percent oxygen.