A theoretical analysis of scanning capacitance microscopy is presented. By solving and matching the corresponding Laplace and Poisson equations for vacuum and semiconductor, the potential and charge distributions induced by a rounded tip in a semiconductor sample were found and used to calculate the capacity and its voltage derivative. The results allow us to analyze the dependence of the capacitance on the semiconductor doping level, applied voltage, and tip geometry, and to estimate the spatial resolution of such measurements. © 2003 American Institute of Physics