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Although scanning capacitance microscopy (SCM) is based on the MOS capacitance theory, the measurement frequency is 915-MHz instead of 100 kHz to 1 MHz in conventional MOS capacitance-voltage measurement. At this high frequency, the reactance of the probe tip-to-substrate capacitance can become smaller than the series resistance of the substrate inversion layer, particularly when the surface mobility is degraded. The response of the oxide-silicon interface traps to SCM measurement is also different due to the use of a 10-kHz signal to determine dC/dV. In this paper, we compare experimental and simulation data to demonstrate the effects of interface traps and surface mobility degradation on SCM measurement. Implications on the treatment of SCM data for accurate dopant profile extraction are also presented.