High depth resolution profiling for magnetic-sector secondary ion mass spectrometry (SIMS)

Abstract

Present day ultra-large scale integration technology exploits the variation of material properties on a nanometer scale and requires analytical methods that can provide adequate characterization at that level. Sputtering with sub-keV ions results in shallower penetration of ions, however, the advantages of low energy sputtering in many cases are offset by the development of crater bottom roughness and the problem is more severe at oblique incidence in the sub-keV range. For magnetic-sector SIMS, using sub-keV beams is more challenging, since the sample is biased to create a high extraction voltage for high transmission. In this work, we will discuss SIMS depth profiling of B, Ge delta-doped Si samples by mainly low energy 500 eV O2+ primary beams. The relationship between depth resolution of the delta layers and surface topography measured by AFM is studied. The effect of oxygen flooding and sample rotation, used to suppress surface roughening is also investigated.