The scanning capacitance microscope is a carrier-sensitive imaging tool based upon the well-known scanning-probe microscope (SCM). Scanning capacitance spectroscopy (SCS) is useful to utilize an SCM to delineate pn junctions in Si devices. This article reports the applications of SCS to Si devices such as CMOS and BiCMOS. SCS is shown to resolve device features on the 10 nm scale for several technologies. Ongoing work includes verifying the reproducibility of SCS measurements and using physical modeling to support the empirical assignment of depletion region width and electrical pn junction position from SCS data. Another technology area where two-dimensional pn junction data is useful is in CMOS device isolation.