Dual cathode ion source

An ion implanter, comprising:

• an ion source, comprising:
• a first end wall and a second end wall;
• chamber walls connected to the first end wall and the second end wall to define an ion source chamber, wherein one of the chamber walls comprises an extraction aperture, wherein a ribbon ion beam is extracted through the extraction aperture;
• a first cathode disposed proximate the first end wall;
• a first filament disposed between the first end wall and the first cathode;
• a first bias power supply to bias the first cathode relative to the first filament;
• a first filament power supply to supply a first current to the first filament;
• a second cathode disposed proximate the second end wall;
• a second filament disposed between the second end wall and the second cathode;
• a second bias power supply, different from the first bias power supply, to bias the second cathode relative to the second filament;
• and
• a second filament power supply to supply a second current to the second filament;
• a beam profiler for measuring a beam current of the ribbon ion beam as a function of beam position;
• and
• a controller, wherein the controller is in communication with the ion source and the beam profiler, such that the controller determines a uniformity of beam current of the ribbon ion beam passing through the extraction aperture based on input from the beam profiler and independently controls the output of the first bias power supply and the second bias power supply so as to improve the uniformity of beam current of the ribbon ion beam.