Very high uniformity mass analysed large area ion implantation

The simplification of the reflected beam collection structure for quadrupole and sextupole analysing magnets is described. This analysis technique enables ribbon beams of any width to be mass analysed. There is potentially a uniformity problem when a ribbon beam together with a single mechanical scan movement is used for the implant of large substrates. A technique is described called binary trim uniformity control which enables a uniform implant to be achieved using a beam which is neither uniform or stable. The technique relies on the monitoring of, and corrections to, the integrated dose distribution as the implant proceeds and does not necessarily attempt to make the beam uniform. Using this technique, the uniformity can be improved by an order of magnitude in 10 mechanical scan cycles using an array of overlapping trim plates which have two positions, an in-beam position removing a fixed predetermined fraction of the beam at each beam trim position (trim = 1) or an out-of-beam position (trim = 0).