Deposition of boron nitride thin films by ion beam assisted deposition

Abstract

The deposition of boron nitride as well as other refractory metal nitride thin films (TiN, HfN etc.) normally requires elevated temperatures to avoid problems with film adhesion, residual stress and chemical stability. A system will be described which has produced adherent, stable thin films. The method uses the low temperature technique of ion beam assisted deposition in which the metal is evaporated onto the substrate and bombarded with energetic nitrogen ions. Coatings as thin as 120 nm have been produced using a 5 mA ion beam of 120 keV N 2 +. Boron nitride coatings with a Knoop microhardness in excess of 2500 kg/mm 2 have been produced. Non-mass-analyzed ion beams have been simulated during the depositions and correlated to film properties. The films are characterized using Knoop microhardness tests, ball-on-disc wear tests and coefficient of friction tests. Film properties are studied by optical and scanning electron micrography, spectral reflectivity and index of refraction measurements.