Look What You Made Me Glue: SEMGluTM Enabled Alternative Cryogenic Sample Preparation Process for Cryogenic Atom Probe Tomography Studies

Abstract

Extensive efforts over the past number of years have been applied to develop workflows for sample preparation of specimens for atom probe tomography at cryogenic temperatures. This is primarily due to the difficulty involved in preparing site specific lift out samples at cryogenic temperatures without the assistance of the gas injection system (GIS) as using it under cryogenic conditions leads to nonuniform and difficult to control deposition. Building on the efforts of previously developed GIS free workflows utilising redeposition techniques, this work provides an alternative approach using SEMGluTM, which is an electron beam curing adhesive that remains usable at cryogenic temperatures, to both lift out cryogenically frozen samples, and mount these samples to Si microarray posts for subsequent redeposition welding. This approach is applicable for a full cryogenic workflow but is particularly useful for non-fully cryogenic workflows such as beam sensitive samples, samples that mill easily, and samples with challenging geometries. We demonstrate atom probe analysis of silicon samples in both laser pulsing and voltage mode prepared using this workflow, with comparable analytical performance to a pre-sharpened microtip coupon. An application-based example which directly benefits from this approach, correlative Liquid Cell Transmission Electron Microscopy and cryogenic Atom Probe Tomography sample preparation, is also shown.