The effects of reaction parameters on the deposition characteristics in Al2O3 CVD

Abstract

Deposits of aluminum oxides (Al2O3) have been formed by a chemical vapor deposition (CVD) technique involving the application of gas mixtures of AlCl3, CO2, and H2 onto TiN coated cemented carbide substrates. The relationships between the deposition rate and various reaction parameters such as the gas flow rate, the deposition temperature, the composition of reactant gases, and the system pressure were studied. The CVD of Al2O3 is a thermally activated process and limited by the surface chemical reaction. The apparent activation energy is about 36 kcal/mol at 50 Torr and decreases with the increasing system pressure. The dependence of the deposition rate on the reactant gas composition is affected by the variation of the relative contents of the aluminum donor and the oxygen donor. At a low AlCl3 mole fraction, the deposition rate increases with the AlCl3 mole fraction; however, at higher AlCl3 mole fractions than 1.0×10−2 the deposition rate is mainly influenced by the H2O-forming reaction between CO2 and H2.