Scanning microwave impedance microscopy (sMIM) is an AFM-based technique for materials and device characterization that does not require making electrical contact between the sample and the substrate.It works by reflecting the microwave signal from the tip-sample interface to reveal the electrodynamic properties of the sample surface and sub surface due to the penetration of the near field signal.
By AC-biasing the sample or device under test, sMIM also provides carrier profiling (dC/dV) capability similar to traditional scanning capacitance microscopy (SCM). In the same way, it also uniquely offers mapping of nonlinear resistive properties (dR/dV). With both the sMIM and its AC-sample-bias modulated signals, sMIM is suitable for studying surfaces with complex composition or devices under test with a broad dynamic range, e.g., metallic, semiconducting, and insulating domains. As a near-field method, the resolution is only limited by the tip radius of the probe, and it can easily achieve a lateral resolution of <30 nm for electrical mapping. These unique capabilities make sMIM superior to other AFM-based electrical modes for a broad range of applications.