Water cooled plasma flood source for intense ion beam implantation

A plasma shower for ion beam and process wafer neutralization has been developed. A plasma is produced within an arc discharge chamber enclosed in a source housing with sufficient water cooling so that the housing temperature is close to room temperature. Arc discharge between a filament and the arc chamber ionizes the shower gas atoms or molecules in the are chamber. The low energy electrons together with ions in the plasma drift out of the arc chamber and neutralize the ion beams and the process wafers. The sufficiently cooled source housing prevents radiation to the process wafers and reduces vapor pressures of variety of elements in the arc chamber. Therefore, metal contaminations resulting from the shower operations are very low on the process wafers. The low temperature of the arc chamber reduces the gas leakage rate per unit area from the arc chamber by a factor of ∼2. In this way, the beamline pressure can be kept low while more electrons can be extracted from the plasma source through the apertures with a larger area.