Optical and mechanical properties of nanocrystalline aluminum oxynitride films prepared by electron cyclotron resonance plasma enhanced chemical vapor deposition

Aluminum oxynitride (AlON) films were prepared on silicon, glass and polymer substrates using electron cyclotron resonance plasma-enhanced chemical vapor deposition. The composition, structure, optical and mechanical properties were investigated. It was found that the composition of AlON films varies from nearly pure AlN to Al₂O₃, controlled by O₂ flow rate. Films deposited at room temperature is amorphous with hardness of 9.1-9.4 GPa, while those deposited at high temperature is crystalline with grain size of 10-20 nm. The hardness of crystalline films accords with the mixture rule. All AlON films are transparent and the transmittance increases with increasing O₂ concentration.