TOWARDS A 3D CHARACTERIZATION OF SOLIDS BY MCS(+) SIMS

The three-dimensional (3D) characterization of solids by means of seco ndary ion mass spectrometry monitoring MCs(+) ions is investigated. Th e MCs(+) molecular ions emitted from surfaces upon Cs+ bombardment are found to be well suited for a quantitative data evaluation via relati ve sensitivity factors (RSFs). Laterally resolved ion images recorded with acquisition times of typically a few seconds can be thus transfor med into elemental distribution maps; these exhibit a dynamic sensitiv ity range in excess of 10(2) and a lateral resolution of similar to 2- 3 mu m. From the applied RSFs, local (i.e. erosion-time dependent) spu ttering yields can be derived; together with atomic densities (which m ight be interpolated from pure-element values), a local depth scale (r elative to some reference level) is assigned to each pixel of the 3D d ata volume recorded during the analysis. In conjunction with the eleme ntal concentration values, this provides the possibility of a complete reconstruction of the 3D sample volume removed by sputtering. This ap proach is exemplified and its validity and limitations are assessed by means of a laterally inhomogeneous semiconductor test specimen.