Modelling Of The Ion Energy Spectrum In Electron Cyclotron Resonance Plasmas

The ion energy spectrum in microwave electron cyclotron resonance (ECR) produced plasmas is studied in the presence of a divergent static magnetic field. The analysis is kinetic in which ion-neutral collisions are treated using a Monte Carlo collision algorithm. For a low pressure (< 1 m Torr) argon plasma, results show that the ion energy spectrum near the specimen sheath is peaked at low energy (˜ room temperature). This peak is produced by all the ions that experienced collisions (charge exchange & elastic scattering) with the neutral gas background. A second, and yet much smaller, peak which corresponds to those particles that reached the sheath edge without any collisions, is also observed. This indicates that the effect of the presheath potential in determining the energy of the ions hitting the surface of a substrate is small and that ions acquire the most of their energy in crossing the substrate's sheath. Results showing the variation of the energy spectrum and plasma potential profile with neutral gas pressure will be presented.