Control of Magnetic Field in Neutral Loop Discharge Plasma for Uniform Distribution of Ion Flux on Substrate

The production and transport of ions in a neutral loop (NL) discharge plasma under a quadrupole magnetic field are investigated using a Monte Carlo method. The ion production occurred around the separatrices of the quadrupole magnetic field and decreased as the NL shrunk. The ion flux on the substrate had its peak near the foot of a separatrix. It was demonstrated that the time-averaged ion flux on the substrate can be distributed uniformly by controlling the magnetic field so that the foot of the separatrix sweeps over the substrate.