An investigation of the structural properties of diamond films deposited by pulsed bias enhanced hot filament CVD

The control of the surface roughness and morphology of diamond films is of critical importance for many applications such as for optical and electroni c components. In order to produce uniform CVD diamond films with a controll ed surface morphology over large areas, bias enhanced methods of nucleation offer better reproducibility than substrate pre-treatment methods such as mechanical abrasion. Hot filament chemical vapour deposition (HFCVD) with b ias enhanced nucleation (BEN) has been used to increase thr nucleation dens ity of diamond films on Si{100} substrates. Optimal conditions of the nucle ation step for subsequent growth of good quality diamond were a substrate t emperature of 1100 K; methane/hydrogen ratio of 3%; pressure of 20 Torr; fi lament temperature of similar to 2500 K; d.c. bias of - 250 V and time of 3 0 min. We also demonstrate that re-nucleation of diamond is possible using short intervals of substrate biasing during normal diamond growth. The film morphology and surface roughness critically depend on the length of the bi as cycle and may be controlled without reducing the diamond quality. The mo rphology and quality of the standard negatively biased and pulsed biased fi lms were characterised by scanning electron microscopy and Raman spectrosco py. Atomic force microscopy was used to measure the surface roughness of th e films. (C) 1999 Elsevier Science S.A. All rights reserved.