SECONDARY ION MASS-SPECTROMETRY AS A MEANS OF SURFACE-ANALYSIS

This paper reviews the current state of Secondary Ion Mass Spectrometry (SIMS) applied to the investigation of surfaces. The basic phenomena involved (ion penetration and reflection, ion ranges and sputtering) are discussed in some detail. Aspects of SIMS instrumentation are considered briefly. It is shown that means to record both positive and negative secondary ion spectra as well as energy distributions are mandatory if one attempts to make full use of the potential of SIMS. Adsorption studies require primary ion energies of 500 eV or less in order to avoid destruction of weakly bound states. In favourable cases a depth resolution of one monolayer can be obtained in low damage SIMS studies. Available experimental results suggest that at energies below ∼1 keV, light adsorbates (N, O, CO) are emitted mostly due to direct interaction with the incoming or reflected primary ion rather than by sputtering from collision cascades. Cluster ions are sensitive to the primary ion energy only if weakly bound adsorbates are involved. Some general rules" for the emission of metal oxides cluster are presented. SIMS studies of organics are discussed briefly. © 1979."