Microstructural evolution of sandwiched Cr interlayer in Cu/Cr/diamond subjected to heat treatment

Abstract Inserting a modifying layer between Cu and diamond is essential to solving the interfacial bonding problem in Cu/diamond composites for thermal management applications. In this study, we deposit Cu/Cr bilayer thin films onto a diamond substrate by magnetron sputtering. The microstructural evolution of the Cr interlayer in the Cu/Cr/diamond structure upon heat treatment at 673-873 K was studied in detail. This method facilitates the observation of interfacial microstructure evolution between Cu and diamond in the processing of Cu/diamond composites. The transmission electron microscopy and Auger electron spectroscopy characterization show that a Cu/Cr/Cr3C2/diamond structure is obtained by the reaction of the Cr interlayer with the diamond substrate. The crystallite sizes become larger and some holes are formed on the surface of the Cu/Cr/diamond samples after heat treatment. Interestingly, a thin Cr layer is formed on the top of the Cu film by Cr diffusion through Cu film at the high annealing temperature of 773 K.