Ion energy distribution in H2/Ar plasma in a planar inductive discharge

The ion energy distribution in H-2 and H-2/Ar plasma in a planar inductive discharge was measured using a quadrupole mass spectrometer. The mean ion energy increases with decreasing pressure from 15 to 40 eV with corresponding ion energy distribution width Delta epsilon(i) increasing from roughly 6 to about 14 eV as the discharge pressure decreased from 24 to 1 mTorr. Furthermore the ion energy distribution becomes narrower and the mean ion energy decreases as the fractional argon content is increased. The sheath is found to be slightly collisional. The dominant ions in H-2 plasma in the pressure range investigated (10-40 mTorr) are found to be H-2(+) and H-3(+) of roughly equal densities.