Highly textured AlN films deposited by pulsed DC magnetron sputtering with optimized process parameters

Abstract

The work is oriented towards finding the optimal process parameters of growth of polycrystalline AlN films by pulsed DC magnetron sputtering. The nitrogen concentration varied from 10 to 40 %, total flow of Ar/N₂ gas mixture varied from 60 to 120 sccm, substrate temperatures were 100, 200 and 300 °C. X-ray diffraction, atomic force microscopy, high resolution transmission electron microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy selected area electron diffraction and ellipsometry methods were applied for AlN films characterization. The transition layer at the film-substrate interface was investigated and its polycrystalline structure without preferred crystallite texture was confirmed. Correlations of deposition parameters and films’ texture, mechanical stresses, roughness, elemental and phase composition were found. As a result, optimal deposition parameters were selected to obtain highly textured along c-axis AlN films with reasonable growth rate, low roughness and minimum level of macro- and microstresses.