Influence of the RF power on the deposition rate and the chemical surface composition of fluorocarbon films prepared in dry etching gas plasma

Fluorocarbon (FC) films have technological applications in various fields such as microelectronics and MicroElectroMechanical Systems (MEMS). In this study, thin FC-films were deposited via plasma polymerisation of trifluoromethane (CHF3) onto Si(1 1 1) in a commercial reactive ion etcher (RIE, radio-frequency RF=13.56 MHz). The behaviour of the fluorocarbon deposition rate and the chemical composition as a function of the RF-power was investigated. The deposition rates of FC plasma polymers are strongly dependent on the RF-power. X-ray photoelectron spectroscopy (XPS) of the C 1s core levels reveals that FC-films containing a high percentage of –CF3 type bonds are formed at low RF powers with low deposition rates. However, at high deposition rates, the percentage of CF3 bonds falls off sharply. This work demonstrates that tailoring the chemical composition of FC films is possible by careful variation of film deposition parameters.