The nuclear microprobe: a unique instrument

There are several features characterising high-energy ion interactions with matter which enables techniques which utilise the high-energy ion beam to have unique or advantageous characteristics. (i) The lack of primary particle bremsstrahlung enables Particle Induced X-ray Emission (PIXE) to be carried out with very little X-ray background, and therefore correspondingly high analytical sensitivity. (ii) The ion beam can penetrate many microns beneath the surface of the specimen with relatively little scattering, and therefore information on structures beneath the surface can be investigated at relatively high spatial resolution. (iii) The ion beam has a well defined depth in the sample, the depth depending on its energy, and this allows more complex three-dimensional structures of better depth definition to be micromachined compared with its X-ray counterpart LIGA. Illustrating these three important features are descriptions of recent work carried out on the elemental analysis of single cells, determination of the annealing efficiency of phosphorous implanted diamond, multi-layer integrated circuit fault finding, and proton micromachining of high aspect ratio structures.