Combined substrate polishing and biasing during hot-filament chemical vapor deposition of diamond on copper

Diamond deposition on copper is problematic mainly due to the poor affinity between copper and carbon. Therefore, it becomes necessary to pretreat the substrate surfaces prior to diamond deposition. Several surface pretreatments have been investigated, such as polishing using various abrasives and substrate biasing. In this study, we report new results relating diamond nucleation on copper substrates to a combination of surface polishing and biasing pretreatments. The results show that the combined pretreatments give a higher nucleation density than the two individual treatments. It was found that an increase of 70% in the nucleation density was observed when the surfaces were polished with diamond paste and then negatively biased. Copper surfaces polished with diamond powder and then biased displayed the highest nucleation density obtained. Raman spectroscopy revealed that after negatively biasing the substrate for 30 min, broad D- and G-bands of microcrystalline graphite were present, which completely disappeared with subsequent diamond growth, leaving behind a good-quality diamond film.