Particle-induced x-ray analysis using focused ion beams

Abstract

In addition to the production of secondary electrons and secondary ions, characteristic x-ray emission may also result from ion/solid interactions and is the basis for the well-known analysis technique referred to as particle-induced x-ray emission. Characteristic x-rays may be emitted by either bombardment by MeV protons or heavy ions of a few keV. The advantage to heavy ions is that the x-ray yield is confined to the region near the surface defined by the collision cascade. An advantage of heavy ion-induced x-ray emission over electron-induced x-ray emission is that the Bremsstrahlung is potentially orders of magnitude lower. Thus, ion-induced x-ray spectra may provide for superior peak-to-noise ratios, and there-fore, offers trace element sensitivity compared with elec-tron-induced x-ray emission. In addition, the near surface ion/solid interactions also allow for the possibility of surface analysis or depth profiling. A Dual Beam instrument was used to collect focused ion beam-induced x-ray (FIBIX) spectra. The acquisition of characteristic x-rays from targets via FIBIX is demonstrated and compared with scanning electron microscopy-induced x-ray energy dispersive spectroscopy spectra and is consistent with the theory described above.