1. Introduction
Chromium nitride films have been developed as an ‘industry standard’ coating for tribological or decorative applications [1], [2] and [3]. For reactively sputtered films the predominant structure that forms depends on a number of deposition parameters, which control the energy delivered to the growing film. This includes the bias applied to the substrate, both in terms of its magnitude and the mode in which it is delivered (i.e. RF, DC, pulsed DC, etc.). In this study the system has been characterised to identify the optimum conditions for CrN deposition, then the effect of pulsing the substrate bias in the mid-frequency range (100–350 kHz) during both the ion etching and deposition stages has been investigated. Previous studies have shown that this can significantly increase the ion current drawn at the substrate, possibly due to the initiation of a second plasma discharge [4] in front of the substrate compared to DC biasing and thereby provide enhanced deposition conditions [5], [6] and [7]. The earlier studies utilised pulsed biasing during the deposition of TiO2 and TiN coatings. This is the first study in which this technique has been applied to CrN films and builds upon earlier published work [8] into the effects of ion energy and nitrogen content.