Method of controlling electrostatic lens and ion implantation apparatus

摘要

The ion implantation apparatus deals with an ion beam as a charged particle beam and has an accelerating tube 8 incorporating an electrostatic lens for converging/diverging it. The control of the electrostatic lens is carried out as follows. The swept ion beam 4 is received by a single Faraday cup 46 to measure the beam quantity I(n) and the beam width WD(p) of the ion beam 4. The evaluated values of the beam quantity and beam width with respect to prescribed standards are calculated. These evaluated values are assigned weights to calculate a unified evaluated value. The focusing voltage Vf applied to the electrostatic lens with the accelerating tube 8 is controlled so that the unified evaluated value is increased. A waveform shaping controller 50 and beam controller 54 constitute a device for making such control.