Microstructure and surface morphology of thin AlN films formed on sapphire by dual magnetron sputtering

Abstract

Results of studies of the effect of the discharge current on the crystalline structure, surface morphology, and thickness of thin AlN coatings deposited by reactive dual magnetron sputtering on c-axis oriented sapphire wafers have been described. Using grazing incidence X-ray diffraction, it has been determined that the coatings have a wurtzite crystalline structure and at least two types of grains with different orientations of the (002) planes. Electron microscopy has revealed that the coatings are composed of vertically aligned columnar grains and a nucleation layer. The grains are uniformly distributed over the substrate surface; each of the grains consists of smaller crystallites. It has been found that the discharge current largely affects the concentration of grains of different orientations and has hardly any effect on the size of the nuclei.