Spatial fluctuation of dielectric properties in Hf-based high-k gate films studied by scanning capacitance microscopy

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 d_{C /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 (V_FB) shift and spatial fluctuation. In every sample, the spatial fluctuations of gate capacitance (C_OX) are less than 3%. Considering V_FB shift and C_OX fluctuations, HfSiON was found to be a promising candidate for gate dielectric applications.