NUCLEATION AND SELECTED-AREA DEPOSITION OF DIAMOND BY BIASED HOT-FILAMENT CHEMICAL-VAPOR-DEPOSITION

This paper describes a process for uniformly enhancing the nucleation density of diamond films on silicon (Si) substrates via de-biased hot filament chemical vapor deposition (HFCVD). The Si substrate was negat ively biased and the tungsten (W) filaments were positively biased rel ative to the grounded stainless steel reactor wall. It was found that by directly applying such a negative bias to the Si substrate in a typ ical HFCVD process, the enhanced diamond nucleation occurred only alon g the edges of the Si wafer. This resulted in an extremely nonuniform nucleation pattern. Several modifications were introduced to the desig n of the substrate holder, including a metal wire-mesh inserted betwee n the filaments and the substrate, in the aim of making the impinging ion flux more uniformly distributed across the substrate surface. With such improved growth system designs, uniform enhancement of diamond n ucleation across the substrate surface was realized. In addition, the use of certain metallic wire mesh sizes during biasing also enabled pa tterned or selective diamond deposition.