Influence of bowl shaped substrate holder on growth of polymeric DLC film in a microwave plasma CVD reactor

Abstract

The properties of diamond like carbon (DLC) films grown in modified microwave plasma CVD reactor is presented in this paper. By using bowl shaped steel substrate holder in a MW plasma CVD reactor (without ECR), films have been grown at relatively high pressure (20 Torr) and at low temperature (without heating). The input microwave power was about 300 W. Earlier, under the same growth conditions, no deposition was achieved when flat molybdenum/steel substrate holders were used. In this study, two different designs of bowl shaped steel substrate holder at different bias have been experimented. Raman spectra confirm the PLC characteristics of the films. FTIR results indicate that the carbon is bonded in the sp(3) form with hydrogen, and this characteristic is more pronounced when smaller holder is used. UV-visible spectra show high visible transmittance (similar to 85%) for films grown in both the holders. The nanoindentation hardness of the films have a wide range, about 4-16 GPa. Field emission scanning electron microscope (FESEM) images reveal that the films have featureless and smooth surface morphology. These films are polymeric in nature with moderately high hardness, which may be useful as anti-scratch and anti-corrosive coatings.