ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The electron energy relaxation in space has been investigated for electropositive Ar and electronegative SiH4 discharges by a 1D Particle-in-cell/Monte Carlo code. The ionization rate has been studied since this rate is strongly influenced by the energy relaxation mechanism. The ionization rate in the two kinds of discharges at a low pressure (30 mTorr), a low power (8 W), and a low frequency (13.56 MHz) is regarded as the reference case. The effects of pressure, power, and frequency on the ionization rate have been observed and compared between the two types of discharges. With the pressure increasing from 30 to 400 mTorr, in the case of the argon discharge the ionization peak moves from the plasma bulk (nonlocal behavior of the electron energy distribution function) towards the momentary cathodic presheath (local behavior). In addition to a similar variation of the ionization rate, in the silane discharge an ionization peak occurs near the momentary anodic presheath, and at the high pressure the ionization in the plasma bulk is still considerable. The power can only influence the ionization rate quantitatively. The effect of frequency on the ionization rate is similar for both kinds of discharges. With increasing frequency the ionization rate tends to a somewhat local character, i.e., the ionization appears closer to the momentary cathode. This is attributed to the fact that at the high frequency a bulk electric field in the bulk is found clearly out of phase with the sheath fields, and the energetic electrons are pushed towards the cathode earlier in space. Meanwhile, in the silane discharge the distinctive ionization, which is strongly present at the anodic presheath and in the plasma bulk at low frequency, almost disappears. © 2000 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.372392
