Positional stability of focused ion beams

Probe position stability of focused ion beams in a 100 kV focused ion beam implanter has been investigated. The best result gave a steady probe ion beam with a fluctuation of about 0.1 µm. The ion beam position fluctuates with unstable ion emission. These fluctuations are due to the following two reasons. The first is the extractor voltage variation which is usually required to stabilize the ion emission (a kind of deflection effect). The second seems to be the movement of the Taylor cone itself whose apex represents the actual source position. The results suggest that the Taylor cone on a smaller emitter apex would hardly move, even if the ion emission is unstable.