Calibration of shielded microwave probes using bulk dielectrics

TL;DR

This paper presents a microfabricated stripline microwave probe for precise dielectric measurements, improving shielding and localization compared to traditional probes, enabling quantitative analysis of bulk dielectric properties.

Contribution

The study introduces a novel shielded stripline microwave probe design and demonstrates its ability to accurately measure dielectric constants through finite-element analysis fitting.

Findings

The probe effectively localizes microwave interactions around the tip.

Approaching curves can be quantitatively simulated and fitted.

Peak signals correlate with dielectric constants of bulk materials.

Abstract

A stripline-type near-field microwave probe is microfabricated for microwave impedance microscopy. Unlike the poorly shielded coplanar probe that senses the sample tens of microns away, the stripline structure removes the stray fields from the cantilever body and localizes the interaction only around the focused-ion beam deposited Pt tip. The approaching curve of an oscillating tip toward bulk dielectrics can be quantitatively simulated and fitted to the finite-element analysis result. The peak signal of the approaching curve is a measure of the sample dielectric constant and can be used to study unknown bulk materials.