Depth Profiling SIMS analysis

Depth Profiling SIMS (DSIMS) In SIMS depth profiling analysis the intensity of the secondary ion signals is recorded as a function of erosion time. The concentration of the elements being analysed are derived from the "relative sensitivity factors" of these elements, using appropriate SIMS reference materials. To provide a depth scale, the erosion time is converted to depth of by accurately measuring the depth of the resulting crater. If different layers are present, one also has to ensure that the varying erosion rates of the various layers are taken into account. Whilst quantification in SIMS analysis is normally valid for dilute dopants or impurities (<1 atom%) in homogenous matrices, special protocols are available for the measurement of bulk composition of certain alloys (e.g. SiGe) or high concentrations of dopants. Magnetic sector spectrometers are commonly used for depth profiling application. This is partly due to the ability of the magnetic spectrometers to resolve atomic ions from molecular ion of the same nominal mass. An example is P31 which occurs at the same mass as SiH31. The most important applications in this case are a host of semiconductor materials (silicon, III/V and II/VI) and photovoltaics. For analysis of very near surface regions, or high depth resolution requirements see ule-SIMS.

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