Search

Abstract: 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. [Copyright &y& Elsevier]

In this paper, energy measurements of sheath-accelerated secondary electrons were carried out during plasma immersion ion implantation (PIII) based on a temperature-controlled semiconductor detector. Reducing secondary electrons incident to the detector having an integrating circuit, a voltage step corresponding to incidence of single secondary electron was observed. Step height analysis for the detector output enabled us to give kinetic energy of the secondary electron, and the measured energy was found to be proportional to the sheath voltage. The operating pressure hardly had an influence on the kinetic energy for the pressure less than ∼1.3 Pa. Therefore collision effects in the gas phase was negligible on this measurement. [Copyright &y& Elsevier]

This paper describes effects of vacuum ultraviolet (VUV) optical emission from the plasma on the secondary electron emission coefficient (SEEC) in PIII processes. To examine this, time-resolved measurements of the VUV emission intensity and the SEEC are performed in continuous and square-wave-modulated discharges. For all the measured data, a good linearity between the SEEC and the VUV intensity is found out, and the ion-induced SEEC can be distinguished from the photon-induced SEEC. In the afterglow of the modulated discharge, the SEEC decreases because the VUV emission intensity. Therefore, ion implantation in the afterglow allows us to reduce a current requirement of the pulse generator, leading to low-cost PIII processes. [Copyright &y& Elsevier]

This paper reported measurements of secondary electron emission coefficient (SEEC) during plasma immersion ion implantation and its application to in situ process monitoring of surface conditions. In order to obtain the SEEC, the ratio of a target total current to its secondary electron current component was measured. The secondary electron current was measured with a semiconductor detector located in front of the target. In the PIII process based on an oxygen-mixtured discharge, the SEEC increased with the process time, then saturated. The time variation of the SEEC shows a fairly good agreement with that of the oxygen implantation depth measured by XPS analysis. This result suggests that the SEEC measurement is applicable to end-point detection for the PIII process. [Copyright &y& Elsevier]