Near-field scanning microwave microscopy (SNMM) continues to be developed since its first demonstration in 1972 [1]. SNMM is attractive because it offers a non-invasive method for localized material measurement [2]. Coaxial near-field probes with a tapered protruding center conductor are good candidates for SNMM, in part because they reduce far-field effects [2-4]. The short tip height (～10 μm) of currently available SNMM coaxial probes, however, involves an unwanted electromagnetic interaction between the chip body and the sample, resulting in parasitic capacitance [4-6]. One way to decrease this parasitic capacitance and to achieve a more localized measurement is to use taller tips. To demonstrate this approach, we have designed and fabricated ultra-tall coaxial tips (having heights up to 50 μm) and integrated them with the cantilever and a coplanar waveguide (CPW), as shown in Fig. 1 [4,7]. Here, we present the first results from simultaneous SNMM and AFM measurements using these probes.
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