Simulation study for ion beam extraction of 150 keV/2mA ion implantor by using SIMION 8.1

Abstract

Abstract A simulation of ion beam extraction and beam formation process for 150 keV/2mA ion implantor using SIMION 8.1. has been done. This simulation is aimed to provide an overview of the influence of the geometry and the effect of the variation of the voltage of both extractor and the acceleration tube of the ion source of ion implantor on the trajectory, beam diameter and beam emittance. The simulation was carried by varying the amount of particles that went through the acclerating tube, varying the accelerating voltage, and the extraction voltage, from 50 to 3000 particles, from 30 kV to 150 kV, and from 1 kV to 10 kV respectively. The simulation results show that the ion extraction process and the ion beam formation at the ion source of ion implantor is very dependent on the geometry and the voltage of both electrode and the extractor on the device. The incorrect electrode geometry and voltage would cause the particle trajectory to be non-linear, while the angle of the beam would diverge too much. We’ve also found that the amount of simulated particle would affect the homogeneity of the cross section of the beam. The bigger the amount of the simulated particle, the more homogeneous and stable the beam becomes. Unfortunately, for 3000 particles the running process was very long and prone to errors. Therefore in this simulation, the amount of particles is set to 2000, which gave us a rather uniform beam cross section. The variation of extraction voltage 1 kV to 10 kV while keeping the accelerating voltage constant at 150 kV produced an increment of the diameter of the ion beam from 3.84 cm to 4.12 cm. The variation of accelerating voltage from 30 kV to 150 kV while keeping the extraction voltage constant at 10 kV caused the spot diameter of the ion beam to increase. The value of the spot diameter of the ion beam when the accelerating voltage is kept at 150 kV are 4.12 ± 0.05 cm and 4.05 ± 0.05 cm for y-axis and x-axis respectively.