Nanometer-Scale Materials Contrast Imaging with a Near-Field Microwave Microscope

TL;DR

This paper demonstrates a near-field microwave microscope capable of high-resolution, topography-free contrast imaging of doped silicon at the nanometer scale, revealing local variations in sheet resistance with minimal influence from surface topography.

Contribution

It introduces a novel application of near-field microwave microscopy for nanometer-scale, topography-free contrast imaging of doped silicon, achieving high spatial resolution.

Findings

Spatial resolution of about 100 nm in sheet resistance contrast

Effective imaging over a broad frequency range

Ability to distinguish doped regions with different resistances

Abstract

We report topography-free materials contrast imaging on a nano-fabricated Boron-doped Silicon sample measured with a Near-field Scanning Microwave Microscope over a broad frequency range. The Boron doping was performed using the Focus Ion Beam technique on a Silicon wafer with nominal resistivity of 61 Ohm.cm. A topography-free doped region varies in sheet resistance from 1000Ohm/Square to about 400kOhm/Square within a lateral distance of 4 micrometer. The qualitative spatial-resolution in sheet resistance imaging contrast is no worse than 100 nm as estimated from the frequency shift signal.