High compressive stress is one of the major problems preventing any application of cubic boron nitride thin films at the present time. In order to solve this problem, a detailed understanding of the origins of stress formation in c-BN films is required. According to Davis' model, the stress is determined by a balance of defect (interstitial) generation and recombination. By means of TRIM calculations, we investigated the interstitial generation as a function of important process parameters such as the ion energy and ion mass. Based on these calculations, the Davis model predicted, for example, a stress reduction with increasing ion energy. In our experimental work, we investigated the stress of depth-resolved c-BN films by means of the bending of cantilevers on specially designed substrates. The dependence of the stress on the major deposition parameters (ion energy, ion mass (by varying the Ar/N-2 ratio) was established, e.g. a decrease in stress was observed with increasing energy, as predicted by the model. Furthermore, the incorporation of Ar ions within the films was studied by means of ERD measurements. Although the argon content increases with increasing Ar fraction in the ion beam to a maximum value of approximately 2%, it can be concluded that Ar yields a major stress contribution. Rather, the incorporated Ar is situated at the grain boundaries of the nanocrystalline films which also play an important role in stress release.