Scanning capacitance microscopy using a self-sensing probe has been applied to the quantification of local dielectric properties in Hf-based high-k films grown by an atomic layer deposition method. Local capacitance spectroscopy revealed distinctive contrasts in dC/dV and dC/dZ images originating from the spatial distribution of fixed charges in the films. We also found that the HfSiON film shows better performance than HfSiO and HfO2, in terms of flat-band voltage (VFB) shift and spatial fluctuation. In every sample, the spatial fluctuations of gate capacitance (COX) are less than 3%. Considering VFB shift and COX fluctuations, HfSiON was found to be a promising candidate for gate dielectric applications.