Role of surface pre-treatment in the CVD of diamond films on copper

Diamond films have been deposited on copper substrates using hot filament chemical vapour deposition (HFCVD). In order to improve the nucleation density, several methods of surface pre-treatment and substrate biasing have been investigated. These included polishing the substrates using a number of diamond powders and diamond pastes followed by ultrasonic cleaning. We show that the nucleation density on copper is highly dependent on the particle size in the polishing materials and on the polishing duration. Negative d.c.-biasing enhances more effectively the diamond nucleation on copper than the abrasion process. This method is also much more controllable, reliable and reproducible. High quality diamond films on copper have been produced via HFCVD using a precursor gas mixture of 1% methane in hydrogen. The as-deposited diamond films were characterised for film morphology, crystallinity, film quality and phase purity by scanning electron microscopy (SEM) and Raman spectroscopy. Raman spectroscopy analysis revealed an intense diamond peak at around 1332 cm(-1) and nearly no graphite band. Diamond crystals of predominantly [111] orientation were evident from SEM analysis, Both the diamond phase purity and the nucleation density were enhanced in films deposited by the bias-enhanced nucleation (BEN) method as compared to the diamond deposited on abraded copper substrates. (C) 1999 Elsevier Science S.A. All rights reserved.