Measurement Capability of Scanning Microwave Microscopy: Measurement Sensitivity Versus Accuracy

Here, we investigate the measurement capability of a near-field scanning microwave microscope (SMM) using an atomic force microscope with several types of matching circuits for the characterization of high-permittivity dielectric materials. A fixed impedance matching circuit is generally used in SMM products. In this paper, we propose two types of passive interferometer circuits for the application of SMM systems in laboratories. Both systems are useful for operators without knowledge of microwave measurements; however, they are somewhat limited in their measurement ranges and accuracy when performing high-reflection measurements in the characterization of high-permittivity dielectric materials. Thus, we investigate the stability and the accuracy of SMMs with both setups for measurements on high-permittivity dielectric materials; here, we show that an SMM with an interferometric circuit can achieve a low data distribution and a high-dynamic range, and is, therefore, capable of quantitatively characterizing high-permittivity dielectric materials over frequencies higher than approximately 8 GHz.