Some growth peculiarities of a-C : H films in ECR microwave plasma

The chemical vapor deposition (CVD) process of a-C:H films from methane and argon gas mixtures in an electron cyclotron resonance (ECR) microwave plas ma has been studied. The formation of a-C:H films in a wide range of basic parameters has been investigated. The basic parameters are the following: t he total pressure of the working gas mixture, the composition of the gas mi xture, the magnitude of microwave power absorbed in a plasma, the location of the substrate LECR-S with respect to the position of ECR and substrate m aterial (Si, ceramic). We found that extremely low or zero growth rate of t he a-C:H films takes place in the cases when (i) the substrate is placed in the ECR plane or its close vicinity and (ii) a high microwave power is use d; the latter situation occurs when the power is about 300 W or greater. Th e increase in deposition rate takes place under the increase of the LECR-S distance or under the decrease of the microwave power. The deposition rate of a-C:H films on the ceramic substrate was higher than that on the silicon substrate for all values of operating pressure. These peculiarities are ex plained in terms of additional heating of Si substrates by microwave power absorption outside the ECR region. A later (latent) parameter should be tak en into account in the analysis of the deposition process and choice of the substrate material. The mechanism leading to a very high growth rate of a- C:H polymer-like films is discussed. (C) 2001 Elsevier Science Ltd. All rig hts reserved.