Metal-containing amorphous carbon film development using electron cyclotron resonance CVD

Abstract

A technique for depositing metal-carbon (Me-C:H) thin films is a demonstrated based on two metal screen grids embedded within an electron cyclotron resonance chemical vapour deposition (ECR-CVD) system. The grids are negatively biased and supported at adjustable distances above the substrate holder in the deposition chamber. With source gases of methane and argon, sputtering of the metal grids by Ar+ results in the incorporation of metal in the growing carbon films. The amount of metal in the films can be very well controlled over a wide range by varying the bias voltage at the grids, the separation of the grids from the substrate holder and the ratio of CH4/Ar. Furthermore, by separately biasing the substrate holder, the properties of the films can be varied resulting in the formation of a great variety of Me-C:H films with the very different mechanical and structural properties. Tungsten (W-C:H) and molybdenum (Mo-C:H) incorporated carbon films were deposited using this technique, with the metal fractions controlled by varying the flow ration of CH4/Ar and the bias at the substrates. The films were characterised using Rutherford backscattering, X-ray diffraction and Raman scattering measurements, and also in terms of their conductivity, optical absorption and hardness. Large changes are observed in the conductivity and optical gap of the films even at low fraction of metal incorporated. Metal carbides formation was observed for films deposited under bias. The results suggest that the substrate bias has a crucial effects on the incorporation of metal into the a-C:H films and their resulting microstructures. © 2001 Elsevier Science B.V. All rights reserved.