Aluminium oxides ($Al_2O_3$) have been deposited by a chemical vapor deposition technique using $AlCl_3$, $CO_2$ and $H_2$ gas mixture on to TiN-coated carbide substrates.
The effects of deposition time, temperature, gas flow rate, total pressure and $AlCl_3$ partial pressure on the deposition rate and the crystal morphology of $Al_2O_3$ deposit are studied. $Al_2O_3$ deposited at the temperature range between 1000℃ and 1200℃ has corundum structure and it has preferred orientations of ($10\bar{1}4$) and ($11\bar{2}6$). It is found that C.V.D. of $Al_2O_3$ is a thermally activated process and limited by surface reaction. The apparent activation energy of $Al_2O_3$ deposition is about 36 Kcal/mole at 50 Torr and the apparent activation energy varies with the total pressure. The deposition rate increases with the mole fraction of $AlCl_3$ up to 0.01, and then decreases slightly with further increase of $AlCl_3$ mole fraction. And the effect of the supersaturation of reactant gas on the crystal morphology of $Al_2O_3$ deposit are studied.
