Diamond metallization for Mo electroplating

A metallization system for diamond compatible with Mo electroplating is presented. The deposition of the thin films is made by RF sputtering. 2 MeV ⁴He⁺⁺ backscattering spectroscopy, X-ray diffraction and sheet resistivity measurements are used to characterize the metallization. The stability of the metallization is tested in a tube furnace in a vacuum of 7×10^-7 Torr. The metallization consists of an adhesion layer 30 nm thick of Mo, a 240 nm thick TaSi-N diffusion barrier and an additional 200 nm thick Mo layer to facilitate the subsequent electroplating of a heavy Mo film. The Mo adhesion layer is found to react with diamond and form Mo₂C after annealing at 800°C during 30 min. The Ta₂₄Si₃₉N₃₇ film is stable up to 1 h annealing at 900°C, it starts losing nitrogen close to the surface for 1 h annealing at 1000°C. The Ta-Si-N barrier prevent diffusion of C in the top Mo layer, which needs to be free of N, C, Si and Ta. This requirement is satisfied for annealing of the complete structure at 900°C during 1 h. Mo-Si-N and Mo-N have also been potential candidates for diffusion barrier