The introduction of scanning microwave microscopy (SMM) tools have pioneered many applications, notably including mapping and quantitative measurement of the electrical properties of materials and devices at micro and nano scale. The ability to measure accurately and in a sensitive manner high impedance nanoscale devices is mainly related to the strategy used to match the AFM probe close to the 50 1 impedance of the vector network analyzer (VNA). Different measurement configurations of a homemade interferometric matching network inserted between the AFM probe and the VNA are studied. Measurement sensitivity and accuracy related to nanoscale metal oxide semiconductor (MOS) structures are discussed.