Oxygen-Induced Residual Stress Reduction of Cubic Boron Nitride Films: Reinterpretation of Ye’s Results Considering Interfacial Turbostratic Boron Nitride Layer

The effective residual stress reduction in a cubic boron nitride (cBN) thin film by the addition of oxygen gas is reported. Typically, a turbostratic BN layer (tBN) deposits on the substrate surface prior to a cBN layer. This interfacial tBN layer has been observed that the addition of oxygen increases the thickness of the tBN layer, which is also a factor in reducing the residual stress. In this study, the cBN and tBN layers are analysed to assess their individual effect on residual stress reduction when oxygen is added. The variation in residual stress in relation to the tBN layer thickness is estimated using data reported previously by Ye et al. The estimated data shows that the reduction in the residual stress of the cBN layer is significantly greater than that caused by an increase in the tBN layer thickness. This result shows that the residual stress of the cBN layer can be significantly reduced by the addition of oxygen.