Sheath and presheath dynamics in plasma immersion ion implantation

For plasma immersion ion implantation (PIII) the ion flux onto the target is determined by the expansion of the plasma sheath during the voltage pulses. Spatially resolved probe measurements of the electron density during the pulses in the plasma sheath and presheath are presented. An empirical model is used to describe the delayed reaction of the original presheath to the moving sheath edge and the formation of a new presheath. An increased electron density far away from the target, probably caused by electrons displaced by the sheath or secondary electrons, is also detected. Additionally, the refill of the depleted sheath after the pulses is observed and described.