De-embedding techniques for nanoscale characterization of semiconductors by scanning microwave microscopy

The paper presents a methodology for de-embedding scanning microwave microscopy (SMM) measurements, mainly for semiconductor characterization. Analytical modeling, a parametric study and experimental verification are presented. The proposed methodology is based on the analysis of system response in the linear scale, instead of the dB scale commonly utilized in RF measurements, and on expressing the standard calibration capacitances per unit area. In this way the total measured capacitance is determined by the tip area which is then obtained as a result of the model fitting on the experimental data. Additional evaluation is performed by a straightforward experimental comparison with the usually adopted technique that is based on the electrostatic force microscopy approach curve method. The results obtained by the application of both techniques on the same tip during the same experiment were found to be in good agreement and moreover allowed a detailed discussion on the features of each one of the two methodologies. The paper provides also in this way useful knowledge for the potential users in order to choose the most appropriate technique according to the corresponding SMM application.