Comparison of microwave and lower frequency discharges for plasma polymerization

Abstract

A plasma sustained by electromagnetic surface waves (SW’s) has been used to study the deposition rate R of hydrocarbon and fluorocarbon plasma polymer films as a function of the applied field frequency f in the range 12–400 MHz. The SW technique allows one to vary only f while keeping constant all other parameters known to influence R, for example, power density P in the plasma. A plot of R/P at a total pressure of 200 mTorr (27 Pa) displays two plateaus, that at f100 MHz. This is attributed to the fact that electron energy distribution functions differ fundamentally at radio and microwave frequencies, for the gas pressure range considered.