Patent ID: 8241924

Claim:
A method for controlling an implantation process, comprising: determining a variation of critical dimensions (CD) of a semiconductor wafer; performing an implantation process on the wafer with an ion beam having an initial beam current; moving the semiconductor wafer with a scan arm along an arcuate path at an angular velocity during the implantation process; and varying the angular velocity of the movement of the semiconductor wafer along the arcuate path during the implantation process so that an implant dose into the semiconductor wafer is varied based on the variation of CD, wherein varying the angular velocity includes determining an actual scan speed of the semiconductor wafer based in part on a ratio of a measured beam current to the initial beam current; wherein determining the actual scan speed includes applying an implant-localize control algorithm expressed as: Actual-Scan Speed=Nom-Scan Speed*(1/R)*(Measured-Beam-Current/Initial-Beam-Current), wherein R represents a length of the scan arm.