Composition of alumina films grown on Si at low temperature with catalytic CVD

The X-ray photoelectron spectroscopy (XPS) measurements have been used to reveal the compositions of alumina (Al2O3) films formed on Si wafers using tri-methyl aluminium (TMA) and molecular oxygen (O2) with catalytic chemical vapour deposition (Cat-CVD). The atomic ratio (O/Al) for Al2O3 samples formed at substrate temperature of 200-400 °C has been obtained to be 1.4 which is close to stoichiometry. The increase of growth rate at substrate temperatures below 200 °C and above 400 °C can be attributed to formation of aluminum oxides with non-stoichiometry and metallic aluminum incorporated in the films resulting from deficient oxygen. Angle resolved XPS measurements have revealed that the alumina/Si interface with no SiO2 film has been obtained at substrate temperatures below 200 °C.