Ion implanter optimizer scan waveform retention and recovery

A method for controlling dose uniformity by an ion beam in an ion implantation system, comprising the steps of:

• a) storing a first optimized scan waveform that has been applied to scan plates of a scanner during a first ion implantation process;
• b) recalling said first optimized scan waveform;
• c) measuring a beam current profile of the ion beam deflected by the scan plates applied with the first optimized scan waveform across a plane defined by a workpiece in an implant position, and determining whether the measured beam current profile is within a predetermined specification for a second ion implantation process;
• d) having determined that the measured beam current profile is outside the predetermined specification for the second ion implantation process, iteratively adjusting said first optimized scan waveform based on the measured beam current profile to obtain a second optimized scan waveform;
• e) normalizing a series of slope values representative of the second optimized scan waveform applied to the set of scan plates that deflect the ion beam and removing a dependency of the second optimized scan waveform on beam energy of the ion beam, and storing the second optimized scan waveform as the normalized series of slope values;
• and
• f) applying said second optimized scan waveform during the second ion implantation process.