Near field scanning microwave microscope based on a coaxial cavity resonator for the characterization of semiconductor structures

In this work, we have designed, simulated and fabricated a near-field scanning microwave microscope based on a coaxial cavity resonator. The coaxial cavity resonator is fed by a Keysight N5242A PNA-X Network Analyzer. The inner conductor of the coaxial resonator is connected to a sharpened tungsten tip home-made in our Lab following an electrochemical process. The transmission coefficient S21, the resonance frequency fr and the quality factor Q are measured as the sharp tip is scanned over the device under test at a fixed sample-tip distance in the near field region. The variations of these parameters are related to the topographical and dielectric properties of a very small region of the material under the tip.