Significant enhancement of ion-induced secondary electron current by photons in plasma immersion ion implantation

This paper describes effects of vacuum ultraviolet (VUV) optical emission on the secondary electron emission coefficient (SEEC) in plasma immersion ion implantation (PIII) processes. To examine this, time-resolved in situ SEEC measurements were carried out for square wave-modulated Ar discharges. The SEEC in the activeglow was enhanced in proportion to the SEEC in the afterglow regardless of the ion-bombarding energy. The SEEC enhancement in the activeglow was caused by photon effects, and was explained by synergistic effects of photon irradiation and ion bombardment. Oxygen addition to the Ar discharge also caused a significant increase in the SEEC, and enhanced both ion-induced SEEC and photon enhancement factor.