Texture development in polycrystalline CrN coatings: the role of growth conditions and a Cr interlayer

The control of the texture of transition-metal nitride coatings by varying the energy of incident ions and the coating thickness and by introducing a highly textured interlayer was demonstrated on polycrystalline CrN coatings grown by reactive magnetron sputtering. Development of the preferred (1 1 1) orientation was observed at moderate ion bombardment as the adatom net flux from the (2 0 0) to (1 1 1)-oriented grains dominated. A reversal of this flux at higher ion energies associated with collisional dissociation of N2+ ions at the film surface resulted in the development of a (2 0 0) texture. Coatings composed of grains with mixed (2 0 0) and (2 2 0) orientations were developed under intense ion bombardment due to preferential re-sputtering. The preferred orientation also changes with increasing coating thickness from (2 0 0) towards (1 1 1) through competitive growth. In contrast, a complete (2 0 0)-oriented structure of the CrN layer is formed when it is grown on a Cr interlayer with strong preferred (2 0 0) orientation.