AFM-compatible near-field scanning microwave microscope with separated excitation and sensing probes

TL;DR

This paper introduces a novel near-field scanning microwave microscope with separated excitation and sensing probes, enabling high-resolution imaging of buried structures, nanoparticles, and biological samples at 1GHz.

Contribution

The design separates excitation and sensing probes to reduce common-mode signals, improving image quality and resolution in near-field microwave microscopy.

Findings

Successfully imaged buried structures and nano-scale features.

Achieved high-resolution microwave imaging at 1GHz.

Demonstrated robustness for high-speed scanning in contact mode.

Abstract

We present the design and experimental results of a near-field scanning microwave microscope (NSMM) working at a frequency of 1GHz. Our microscope is unique in that the sensing probe is separated from the excitation electrode to significantly suppress the common-mode signal. Coplanar waveguides were patterned onto a silicon nitride cantilever interchangeable with atomic force microscope (AFM) tips, which are robust for high speed scanning. In the contact mode that we are currently using, the numerical analysis shows that contrast comes from both the variation in local dielectric properties and the sample topography. Our microscope demonstrates the ability to achieve high resolution microwave images on buried structures, as well as nano-particles, nano-wires, and biological samples.