Prototype of a 2.45 GHz cylindrical ceramic dielectric antenna surface wave plasma source for flood gun

In modern ion implanters, plasma flood gun (PFG) is used to neutralize wafer charge during doping process, preventing the breakdown damage of floating wafers caused by the space charge accumulation. Surface wave (SW) plasma source is a potential choice for PFG, because of its no metal pollution, simple structure, high current intensity and low cost for ion implanters. At Peking University (PKU), a 2.45 GHz surface wave PFG (SW-PFG) with a cylindrical dielectric antenna was designed and tested recently. It aims to obtain plasma at the gas pressure of several 10-3 Pa and below which is strictly required by the ion implanter. A two-dimensional discharge model was established to optimize the cylindrical dielectric antenna structure. Through optimization of operation parameters, the electron current intensity of 88 mA was obtained with RF power 500 W and gas pressure 5.0 x 10-3 Pa in the experiments, which meets the requirement of ion implanters. Further, through optimization of operation parameters, the electron current intensity could reach 140 mA. In addition, by setting the graphite liner to isolate the metal cavity wall and plasma, the improvement in the long-term operation stability has been confirmed, which laid a solid foundation for the industrial application of the SW-PFG.