Improvement in adhesion of diamond film on Cu substrate with an inlay structured interlayer

Diamond films were fabricated by using a two-step process on copper substrates in this study. The first step involved electroplating a chromium (Cr)–diamond composite interlayer on copper substrate and in the second step continuous diamond film was deposited on top using the hot-filament chemical vapor deposition (HFCVD) method. The interfacial characteristics was investigated by indentation tests and the thin film surface morphology, phase structure and residual stress analyzed by scanning electron microscopy (SEM), X ray diffraction (XRD) and Raman spectroscopy. The results show that the diamond particles are deeply imbedded in the chromium layer and the amorphous Cr in the composite interlayer was carburized to Cr3C2 during the CVD process. Low residual stress was detected in the diamond film and good adhesive strength between film and substrate was obtained due to the diamond particles anchored deep in the Cr3C2 matrix. Concentric cracks but no delaminated areas and radial cracks were observed on the periphery of the indentation at indentation load of 441 N.