Deposition of aluminium nitride coatings using a cold wall CVD reactor

Aluminium nitride was obtained in a cold wall reactor using AlCl3 and NH3 as precursors and N2 as a carrier gas. AlCl3 was synthesized in situ by means of an original method based on the SiCl4(g) reaction on Al(s). The substrate used is a cylinder of graphite coated with SiC and heated by high frequency induction. The deposition rate was studied as a function of temperature in the range 900–1500°C, the total pressure varying from 2 to 180 hPa. temperatures an Arrhenius type representation of the kinetics for several pressures indicated a thermally activated behaviour with an apparent activation energy of about 80 kJ mol−1. At high deposition temperatures the deposition rate was almost constant, indicating that the growth is controlled by the diffusion process. The influence of gas composition and total AlCl3 flow rate was also discussed. fferent layers were characterized particularly by means of X-ray diffraction and scanning electron microscopy. The influence of temperature and total pressure on crystallization and morphology was studied.