DEPOSITION OF BORON-CARBIDE THIN-FILM BY SUPERSONIC PLASMA-JET CVD WITH SECONDARY DISCHARGE

Boron carbide thin films have been deposited on Si(100) using superson ic plasma jet chemical vapor deposition from boron trichloride and met hane. Vickers hardnesses have been measured around 30 GPa and have bee n found to be dependent on the substrate temperature and the depositio n rate. Growth rates as high as 80 mu m/h have been achieved and their dependence on substrate temperature is shown. The films are composed solely of pure boron carbide and are not contaminated with chlorine or hydrogen, as found by FTIR and XPS analysis. Micro X-ray diffraction studies indicated that the films were microcrystalline. The influence of a positive bias on the growth rate and composition of boron carbide has also been investigated. We have found that the minimum temperatur e at which films can be grown could be lowered from 550 to 500 degrees C and that the growth rate was significantly enhanced at any substrat e temperature. (C) 1998 Elsevier Science S.A. All rights reserved.