Effect of inter-electrode spacing on structural and electrical properties of RF sputtered AlN films

Abstract

An attempt has been made to correlate the morphological and electrical properties of RF sputtered aluminum nitride (AlN), with target to substrate distance (Dts) in sputter chamber. AlN films, having thickness around 3,000 A, were deposited on silicon substrates with different Dts values varying from 5 to 8 cm. XRD results indicated that the crystallinity of c-axis oriented films increase significantly with decrease in Dts and the FTIR absorption band of the films became prominent at shorter Dts. The surface roughness increased from 1.85 to 2.45 nm with that in Dts. A smooth surface with smaller grains was found at shorter Dts. The capacitance–voltage (C–V) measurements revealed that the insulator charge density (Qin) increased from 3.3 × 1011 to 7.3 × 1011 cm−2 and the interface state density (Dit) from 1.5 × 1011 to 7.3 × 1011 eV−1cm−2 with the increase in Dts.