PROPERTIES OF REACTIVELY DC-MAGNETRON-SPUTTERED A1N THIN-FILMS

In this work the dependence of the properties of reactively d.c.-magnetron-sputtered AlN films on their deposition parameters was investigated. In this set-up, argon was used as the sputtering gas and nitrogen as the reactive gas. The argon-to-nitrogen ratios varied between 1 to 3 and 3 to 1, at three different total gas flows: 50 sccm, 100 sccm and 200 sccm. The d.c. power was kept constant at 1 kW. All films showed a polycrystalline hexagonal structure; the refractive index at 550 nm of the series grown at 50 sccm was scattered around 2.12, for the series grown at 100 sccm around 2.05, and for the series grown at 200 sccm around 1.97. Localized gap states appeared in films grown at 50 sccm with an Ar-to-N2 ratio of 3 to 1. The films grown at flows of 100 sccm and 200 sccm showed tensile stresses (up to 1 GPa). The films grown at 50 sccm showed a transition from compressive (-1.3 GPa) to tensile stress (0.3 GPa) if the Ar-to-N2 ratio was increased to more than 2 to 1.