Fabrication of on-chip probes for double-tip scanning tunneling microscopy

TL;DR

This paper presents a novel fabrication method for on-chip double-tip STM probes with a fixed 35 nm separation, enhancing precision and stability for nanoscale measurements in scanning tunneling microscopy.

Contribution

The authors develop a lithographic fabrication process for on-chip double-tip STM probes with fixed nanometer-scale separation, improving integration and mechanical stability.

Findings

Achieved 35 nm fixed tip separation using lithography.

Demonstrated easy integration with existing STM/AFM systems.

Provided mechanically stable and lithographically defined tips.

Abstract

Reduction of the inter-probe distance in multi-probe and double-tip STM down to the nanometer scale has been a longstanding and technically difficult challenge. Recent multi-probe systems have allowed for significant progress by achieving distances of around 30 nm using two individually driven, traditional metal wire tips. For situations where simple alignment and a fixed separation can be advantageous, we here present the fabrication of on-chip double-tip devices that incorporate two mechanically fixed gold tips with a tip separation of only 35 nm. We utilize the excellent mechanical, insulating and dielectric properties of high quality SiN as a base material to realize easy-to-implement, lithographically defined and mechanically stable tips. With their large contact pads and adjustable footprint these novel tips can be easily integrated with most existing commercial combined STM/AFM systems.