The physical principles of scanning capacitance spectroscopy

Measurements of two-dimensional dopant profiles by means of conventional scanning capacitance microscopy contain uncertainties concerning the quantification of the charge-carrier distribution due to parameters of the capacitance sensor, the probe and the sample itself. Thus an improved sample preparation is presented which is mainly based on a UV-ozone-oxidation process. Further, it is shown how to handle the actual tip shape by aligning a standard calibration curve to the measurement of a known dopant value of the sample. However, the main topic is the influence of the bias voltage on the measurements. It is shown that measurements at non-zero voltages improve the lateral resolution as well as the dopant resolution. To achieve the required data, scanning capacitance spectroscopy (SCS) is the proper method. It is suggested to modify the SCS method into a high-speed SCS to overcome unreliabilities of the measurements due to hysteresis effects.