IN SITU BEAM CURRENT MONITORING AND CONTROL IN SCANNED ION IMPLANTATION SYSTEMS

摘要

A system and method for controlling an ion implantation system as a function of sampling ion beam current and uniformity thereof. The ion implantation system includes a plurality of ion beam optical elements configured to selectively steer and/or shape the ion beam as it is transported toward a workpiece, wherein the ion beam is sampled at a high frequency to provide a plurality of ion beam current samples, which are then analyzed to detect fluctuations and/or nonuniformities or unpredicted variations amongst the plurality of ion beam current samples. Beam current samples are compared against predetermined threshold levels, and/or predicted nonuniformity levels to generate a control signal when a detected nonuniformity in the plurality of ion beam current density samples exceeds a predetermined threshold. A control system can be configured to generate a control signal for interlocking the ion beam transport in the ion implantation system or for varying an input to at least one beam optical element to control variations in beam current.