Low-temperature deposition of nanocrystalline Al2O3 films by ion source-assisted magnetron sputtering

Abstract

In this paper, bipolar pulse reactive magnetron sputtering with ion source assisted deposition method has been utilized for the deposition of nanocrystalline alumina (Al2O3) films at the temperature of 300 °C onto silicon (111) wafers, and cemented carbide substrates. The influence of ion source power, i.e. 0, 1.0, 1.5 and 2.0 kW on the structure, morphology, compressive stress and mechanical properties of the Al2O3 films were investigated. In absence of ion source power assistance, an amorphous Al2O3 film was dominant at deposition temperature of 300 °C. With ion source assisted deposition, the crystalline γ-Al2O3 films were obtained at the same conditions, suggesting an importance of ion source power in crystallinity development of metal oxide films obtained from magnetron sputtering deposition method. Images of surface morphology clearly demonstrated the difference in granular sizes of film surfaces prepared with and without ion source powers. With increasing ion source power from 1.0 to 2.0 kW, the micro-hardness and compressive stress of the films were increased from 7 GPa to 13 GPa and 0.3 GPa to 1.1 GPa, respectively. Results revealed that the reactive magnetron sputtering with the ion source assisted deposition was a simple and effective way to prepare nanocrystalline γ-Al2O3 films at low temperature.