Microstructure and characterization of aluminum oxide thin films prepared by reactive RF magnetron sputtering on copper

The influences of the deposition parameters on the properties of aluminum oxide thin films deposited on copper substrates by reactive RF magnetron sputtering with an aluminum target are investigated in this study. The base pressure and argon flow rate were fixed at 8 mTorr and 10 sccm, respectively. The microstructure, composition and oxidation behavior of the aluminum oxide films were characterized respectively by transmission electron microscopy, Auger electron spectrometer and derivative thermogravimetry. It was found that an excellent aluminum oxide coating is obtained when the power density is 15 W/cm2 and the oxygen flow rate is 3 sccm. An increase in the RF power leads to a dense crystalline structure and a slight decrease in the oxygen/aluminum atomic ratio in the deposited film. Oxygen flow rate higher than 3 sccm causes porous structure of thin films. The properties of thin films are thought to be related to the target poisoning and the degree of ionization of gas atoms in different RF power densities and oxygen flow rates.