In an ion implantation system, departure from uniform ion dosage of a planar workpiece is first compensated by modulating the scan rate of at least one coordinate of scan deflection in accordance with a non-linear waveform. The non-linear waveform is digitally synthesized from a plurality of contiguous...http://www.google.de/patents/US4283631?utm_source=gb-gplus-sharePatent US4283631 - Bean scanning and method of use for ion implantation
