Preparation of highly oriented polycrystalline AlN thin films deposited on glass at oblique-angle incidence

Abstract

A new method to prepare polycrystalline AlN thin films biaxially oriented on amorphous substrates has been demonstrated. The films were deposited at different angles of incidence with a rf sputtering system. Population-1 crystallites, oriented with their c-axis pointing toward the incoming flux with random orientation in aximuthal directions, predominate at low angle of incidence (near normal). Population-2 crystallites result from non-normal incidence and have their c-axis tilted away from the incoming flux and predominate at high, near glancing, angle of incidence. The alignment of crystallites (population-2) increases with angle of incidence. Crystallites align along the [11*0] channeling direction, characterized by a low sputtering yield, while misoriented crystal grains suffer a higher resputtering and their growth is inhibited. For films deposited at 75°, the FWHM of an x-ray ϕ scan profile is 25°, indicating a high in-plane alignment.