Atmospheric pressure chemical vapor deposition mechanism of Al2O3 film from AlCl3 and O2

Aluminum oxide (Al2O3) films were deposited by atmospheric pressure chemical vapor deposition (AP-CVD) method from aluminum trichloride (AlCl3), argon, and oxygen gas mixtures at temperatures ranging from 800 to 1000 °C. Alumina films with crystalline phases of γ- or θ-, and α-alumina were obtained starting at 800 °C. Increase in the relative amount of the α-phase as well as improvement in crystallinity is observed as temperature is increased to 1000 °C. The films have low chlorine content, which continued to decrease with increasing temperature. Analysis of the film growth rate on tubular substrates of varying diameters revealed a diffusion-limited growth from 800 to 950 °C and gas-phase reaction-limited growth at 1000 °C. The growth species is a cluster with size 1.2 nm at 800 °C and 0.9 nm at 950 °C. The gas-phase reaction constant at 1000 °C is 1.1/s.