Electron transport in carbon tetrafluoride along a magnetically neutral plane between constant gradient antiparallel magnetic fields

摘要

Electron motion in CF4 at 0.67 Pa under crossed electric (E) and magnetic (B) fields was simulated by a Monte Carlo method to investigate fundamental properties of electron transport in neutral loop discharge plasmas for dry etching. As a simplified model of the electron path in the plasma, a magnetically neutral plane was assumed between linearly gradient antiparallel B fields, and a uniform E field was applied along the neutral plane perpendicularly to the B fields. The electron behaviour showed two contrasting modes depending on the direction of the B fields relative to the E field. In the field configuration which confines the electrons near the neutral plane, values of the mean electron energy, the drift velocity and the effective ionization frequency were close to those under the dc E field without B field. On the other hand, in the opposite B field configuration, the electrons hardly drifted along the E field, but instead, they showed a constant lateral diffusion driven by the E x B drift. A reverse-blocking effect of the gradient antiparallel B fields is reported.