Scanning capacitance microscopy: quantitative profiling down to nanostructures

We addressed the issues related to quantitative carrier profiling by scanning capacitance microscopy (SCM) on doped layers with different dimensions, starting from thick (similar to 5 mu m) uniformly B-doped Si layers, down to Si/Si1-xGex/Si quantum wells with nanometric width. We preliminarly discussed the influence of the SCM hardware on the quantification, by comparing the analyses performed on Si calibration standards with two different atomic force microscopes, i.e., DI3100 by Veeco and XE-100 by PSIA, equipped with different SCM sensors. Furthermore, both concentration and spatial resolution are demonstrated by measurements on specially designed samples containing B-doped quantum wells of Si0.75Ge0.25 layers strained between Si films. Measurements were taken both on cross-sectioned samples and on beveled ones. A SCM spatial resolution of 1 nm with a concentration sensitivity from 5% to 10% was demonstrated by quantitative majority carrier profiling on the B-doped Si/Si0.75Ge0.25/Si heterostructures.