Dynamic sheath studies in plasma source ion implantation

Summary form only given. Plasma source ion implantation is a non-line-of-sight method for materials processing in which a target is immersed in a plasma and pulse biased to a high negative voltage. A model of the dynamic sheath which forms under these conditions has been developed and applied to planar, cylindrical, and spherical geometries. This model assumes that the transient sheath obeys the Child-Langmuir law for space-charge-limited emission at each instant during the propagation. Ions uncovered by the propagating sheath edge supply the space-charge-limited current. This yields an equation relating sheath edge velocity to position; it can be integrated to obtain the sheath edge position as a function of time. Comparison of results of experimental measurements, the proposed model, and simulation has been performed for the dynamic sheath edge position and target current waveform. Measurements of implanted dose uniformity of wedge-shaped targets were obtained