Energy and composition of the ion flux in microwave electron cyclotron resonance/radio frequency methane plasma

The microwave electron cyclotron resonance/r.f. discharge in methane and methane/argon working gas has been studied by means of the energy resolved ion mass spectrometry. The ion energy distribution and composition of the ion flux at a substrate were measured for microwave powers ranging from 50 to 600 W, r.f. biases from 0 to −200 V and total pressures from 0.05 to 1 Pa. A wide ion energy distribution was found with the ion energies substantially higher than the r.f. generated bias. The major hydrocarbon ion species in the present type of discharge are CH4+ and CH3+ at low pressures, CH5+ and C2H5+ at high pressures in the methane and CH3+ in the methane diluted in argon. The main ion–molecular reactions affecting the plasma composition were identified by the analysis of the variation of hydrocarbon ions intensities with the discharge parameters.