Influence of rapid thermal annealing on morphological and electrical properties of RF sputtered AlN films

Aluminum nitride films were deposited, at 200 °C, on silicon substrates by RF sputtering. Effects of rapid thermal annealing on these films, at temperatures ranging from 400 to 1000 °C, have been studied. Fourier transform infrared spectroscopy (FTIR) revealed that the characteristic absorption band of Al–N, around 684 cm⁻¹, became prominent with increased annealing temperature. X-ray diffraction (XRD) patterns exhibited a better, c-axis, (0 0 2) oriented AlN films at 800 °C. Significant rise in surface roughness, from 2.1 to 3.68 nm, was observed as annealing temperatures increased. Apart from these observations, micro-cracks were observed at 1000 °C. Insulator charge density increased from 2×10¹¹ to 7.7×10¹¹ cm⁻² at higher temperatures, whereas, the interface charge density was found minimum, 3.2×10¹¹ eV⁻¹cm⁻², at 600 °C.