Ion beam analysis methods generally rely on either the scattering of a high energy primary particle, or secondary process arising from the stopping of this particle in the substrate. The information typically obtained is the identification and quantitation of elements present, often resolved in terms of their depth distribution. However, there are a variety of techniques which offer complementary information on the structure composition and chemistry of a surface. These are typified by rather softer interactions with the surface, typified by low energy (kV) ion beams or photons, which interact with the surface in rather more complex manner than higher energy ion beams. The combination of energy and momentum transfer for the ion beams, makes these methods less quantitative, but opens up the potential for more chemically detailed information on the nature of the surface. Secondary ion mass spectrometry (SIMS), both static and dynamic, and X-ray Photoelectron Spectroscopy (XPS) will be discussed in some detail. SIMS offers excellent compositional depth profiling capability, but offers poor quantitation, while XPS offers unparalleled chemical detail, but limited lateral and depth resolution. The underlying processes which dictate the strengths and limitations of these techniques are discussed, along with a number of typical applications to the analysis of oxide films and polymeric materials.
Ion Beam Analysis for the Investigation of Diffusion Processes
