CONTROL-SYSTEM FOR A 300-KV ION IMPLANTER

A complete system has been developed for the control of a 300 kV ion implanter machine. It includes fibre optic links for the monitoring and control of the ion source parameters in the high voltage zone, and a computer system for the characterization of the ion beam and the whole control of an implantation process. With the fibre optic system the ion source anode, cathode and focus voltages and currents are measured, and pressure and magnetic field of the discharge are controlled, allowing the use of the source for obtaining many different ion species with good stability. The computer system offers the possibility of quantitative mass characterization of the complete beam, and management of an implantation, controlling the mass being implanted and stopping the process when any problem is detected. All conversion modules and interface circuits, designed as general purpose circuits, are described. Results of Si-29 and Mg-24 implants into Fe doped semi-insulating InP are shown to demonstrate the purity and reliability of the system developed.