Influence of Al-Si-N interlayer on residual stress of CVD diamond coatings

Here we report the novel interlayer for the high-quality CVD diamond thin films with reduced residual stress. We used the novel sputtering technique of reactive high power impulse magnetron suttering (r-HiPIMS) which allows us to deposit high quality, void- and defect-free AlSiN interlayer films. The film based on Al-Si-N system shows fully amorphous structure at temperature of diamond film synthesis (800 °C), inertness to diamond and hard WC-Co alloy at elevated temperatures and reduction of the diamond macrostress up to −0.25 GPa for film with AlSiN interlayer. Additionally, varying the Al content in Al-Si-N film we can finely tune its mechanical properties and total stress in substrate – AlSiN – diamond system. We show that AlSiN with the combination of its properties overcomes conventionally used interlayer materials for CVD-diamond such as transition metals or their nitrides and carbides.