Growth of diamond films with bias during microwave plasma chemical vapor deposition

Abstract

Diamond films on 3-inch diameter (100) silicon wafers were synthesized with bias during microwave plasma vapor deposition (MPCVD). The deposition parameters were as follows: 0.13% CH4 in H-2 pressure at 30 torr; deposition temperature at 768-869 degreesC, and a deposition time of 3-3.5 h. The bias voltage applied to the substrates during diamond growth varied from 0 to -450 V. The deposited films were characterized by Raman spectroscopy and electron microscopy. The results show that the film properties are uniform across the whole 3-inch diameter area. Raman spectra show that the ratio of sp(3) to sp(2) is increased with the bias voltage up to -350 V, while further increases in voltage resulted in a decreased ratio. It was found that column-shaped grains of diamond were directly grown from the substrate surface without grain coalescence in the lateral direction during growth. The nucleation density of diamond with biased growth was of the order of 10(9) cm(-2). (C) 2002 Elsevier Science B.V. All rights reserved.