Effects of copper interlayer on deposition and flexibility improvement of diamond microelectrode

Tungsten with sputtered copper layer (W/Cu) and bare tungsten (W) substrates were investigated for boron doped diamond microelectrode (BDDME). Traditional tungsten substrate becomes brittle after diamond film deposition and is prone to fracture when BDDME confronts slight bending force in practice because of formation of carbide on the surface of tungsten. To improve the flexibility of the microelectrode, a 100 nm sputtered copper layer has been chosen as a barrier interlayer to hinder diffusion of carbon into tungsten, as copper does not form compounds with carbon and tungsten. We have found that the copper layer greatly curbs the formation of tungsten carbide, making the W/Cu substrates more flexible than W substrates after deposition and the bending angle was up to 40°, which was 4 times higher than that of bare tungsten substrates. Besides, the sputtered copper layer made it easier for diamond nanoparticles to adsorb on the surface, which has improved nucleation and growth of diamond film. High-quality and well-adhesive diamond film without crack and holes has been deposited on the W/Cu substrate.