This paper presents a detailed modeling and characterization of a microfabricated cantilever-based scanning microwave probe with separated excitation and sensing electrodes. Using finite-element analysis, we model the tip-sample interaction as small impedance changes between the tip electrode and the ground at our working frequencies near . The equivalent lumped elements of the cantilever can be determined by transmission line simulation of the matching network, which routes the cantilever signals to feed lines. In the microwave electronics, the background common-mode signal is canceled before the amplifier stage so that high sensitivity (below capacitance changes) is obtained. Experimental characterization of the microwave microscope was performed on ion-implanted Si wafers and patterned semiconductor samples. Pure electrical or topographical signals can be obtained from different reflection modes of the probe.
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The actual tip-sample interface is also affected by the work function difference and small rf oscillating potential. Such effect will slightly modify the sample surface and is not included in our current simulation.