A new approach to ion implanter mass analysis optics

Abstract

The Precision Implant 9000 Ion Implanter uses a mass analysis geometry where the ribbon beam extracted from a Freeman type ion source has the long axis of the ion source extraction slot in the dispersion plane of the magnetic analysis system. This allows the ion source and its associated extraction system to be placed close to the analysis magnet, the length of the extraction slot no longer determining the pole gap necessary for the analysing magnet as would be the case for conventional isotope separator optics. This geometry allows extraction from a long and wide extraction slot or multiple extraction slots, in the latter case each beam seeing the same dispersion plane geometry. The above features, together with an extraction system employing a generous accel/decel ratio results in a machine which will deliver high beam currents from a compact beam line with particularly advantageous extraction gap electrical breakdown characteristics. The design of the mass analysis system incorporates a number of features aimed at minimising cross-contamination caused by sputtering.