Chemical depth profiling on submicron regions : a combined focused ion beam/scanning electron microscope approach

The combination of focused ion beam (FIB) milling and field emission scanning electron microscopy (SEM) with x-ray energy-dispersive spectroscopy (EDS) makes possible high-spatial-resolution (< 1 μm) element-specific depth profiling. The depth profile resolution is controlled via the FIB to < 5 nm sputter depths. Depth profiles through thin-film hard disk media on NiP substrates and through similar film structures deposited on a carbon-coated substrate are presented. The high spatial resolution of the FIB/SEM depth profile is not necessary for blanket films, and depth profiles through them are used to benchmark the spatial and depth resolution of the technique using a field emission SEM. Energy depth profiles that use increasing primary electron beam voltages in the spectrometer are shown on the same samples in comparison to FIB depth profiles. A brief overview of this technique in relation to XPS, AES and SIMS illustrates applications where FIB depth profiling analysis offers some advantages.