REACTION LAYER FORMATION AND FRACTURE AT CHEMICALLY VAPOR-DEPOSITED DIAMOND METAL INTERFACES

Chemically vapor deposited (CVD) diamond films have been deposited by a microwave enhanced deposition process on metal substrates including titanium, tungsten, molybdenum, and copper. Boundary reaction layers f ormed at the interface during the growth of the CVD diamond films have been investigated for each of these systems. In these studies, the in terface has been exposed by mechanically deforming the metal substrate to cause film delamination. Where the diamond film has adhered to the substrate through the growth process, delamination procedures have be en carried out under controlled conditions in order to preserve the in tegrity of the interfacial species. The exposed interfaces were charac terized by x-ray photoelectron spectroscopy, scanning Auger microscopy , secondary electron microscopy, and Raman microprobe spectroscopy. Re action layers composed of carbides and oxides of the native metal were detected at the interfaces of titanium, tungsten, and molybdenum whil e only traces of carbon and oxygen were detected at the diamond/copper interface. We believe that both the chemical composition and morpholo gy of the interface influence the adhesive properties of the diamond c oating. Correlated investigations of the interfacial surfaces reveal t hat fracture of the diamond/metal interface occurs discretely at the d iamond nucleation plane or within a reaction layer near the diamond in terface.