Deposition of c-BN films on diamond: influence of diamond roughness

J. Pascallon, V. Stambouli, S. Ilias, D. Bouchier, G. Nouet (1), F. Silva (2), A. Gicquel (2)

Institu d'Electronique Fondamentale, URA CNRS 22, Bat. 220, Université Paris-Sud, F-91405 Orsay, cedex, France.
(1) LERMAT-ISMRA, boulevard du Maréchal Juin, F-14050 Caen, cedex, France
(2) Laboratoire d'Ingénierie des Matériaux et des Hautes Pressions, CNRS, Université Paris-Nord, Avenue J.B. Clément, F-93430 Villetaneuse, France

ABSTRACT

Diamond films deposited on Si substrates by Plasma Enhanced Chemical Vapor Deposition (PECVD) were used as substrates for c-BN thin film depostion. The c-BN films were deposited at 400oC by Ion Beam Assisted Deposition (IBAD) using a mixture of nitrogen and arogn ions. In term of roughness, two kinds of diamond films were chosen, i.e. naturally rough diamond with roughness values ranging from 100 to 200 nm (r.m.s) and planarized diamond films with a roughness value of 16 nm (r.m.s). From IR analyses, it was shown that the fraction of cubic phase in the c-BN films was depending on the roughness of the diamond surface. As expected, this fraction in cubic phase was optimized in the case of smooth surfaces presenting no particular geometrical effect for incoming energetic nitrogen and argon ions. These results clearly showed the necessity to have planarized and smooth diamond surfaces prior to the c-BN film deposition. TEM study performed on c-BN films deposited planarized diamond revealed that the films were nanocrystalline with columnar grains. A HRTEM study focused on the interface between the c-BN film and the substrate showed the commonly observed layered structure, i.e. a well  textured c-BN volume lying on a h-BN basal layer with the (00.2) planes perpendicular to the substrate.


Article published in Materials Science & Engineering B59 (1999) 239-243.