SHEATH AND PRESHEATH DYNAMICS IN PLASMA IMMERSION ION-IMPLANTATION

For plasma immersion ion implantation (PIII) the ion flux onto the tar get is determined by the expansion of the plasma sheath during the vol tage pulses. Spatially resolved probe measurements of the electron den sity during the pulses in the plasma sheath and presheath are presente d. An empirical model is used to describe the delayed reaction of the original presheath to the moving sheath edge and the formation of a ne w presheath. An increased electron density far away from the target, p robably caused by electrons displaced by the sheath or secondary elect rons, is also detected. Additionally, the refill of the depleted sheat h after the pulses is observed and described.