Doping-dependent contrast in secondary electron images of p/n junctions in silicon obtained in a field-emission scanning electron microscope was observed and characterized. The optimum experimental conditions for observing this ''electronic'' contrast were established by investigating the effect of microscope and material parameters on the magnitude of the contrast. The contrast between the bright p-type areas and the darker n-type areas was maximized at an accelerating voltage of similar to 1 kV, and when a through-the-lens detector configuration was employed. Secondary electron contrast profiles of boron doped p(+)/n junctions in silicon showed a good correlation with secondary ion mass spectroscopy depth profiles of the atomic concentration down to the 10(17) cm(-3) level. However, similar results were not obtainable for n(+)/p junctions. It is demonstrated that this contrast effect may he exploited for obtaining two-dimensional dopant profiles directly from secondary electron images of p(+)/n junctions provided that the technique is empirically calibrated against a one-dimensional dopant profiling method. (C) 1996 American Vacuum Society.
