In-situ sputtering from the micromanipulator to enable cryogenic preparation of specimens for atom probe tomography by focused-ion beam

TL;DR

This paper introduces an in-situ sputtering technique from a micromanipulator to improve cryogenic specimen preparation for atom probe tomography, enabling precise site-specific analysis with enhanced interface strength.

Contribution

It presents a novel method for locally sputtering metal during cryogenic specimen prep, building on existing redeposition techniques to improve interface strength and flexibility.

Findings

Successful atom probe analysis of Si at cryogenic temperatures

Comparable performance to traditional microtip preparation

Versatile sputtering approach with various metals

Abstract

Workflows have been developed in the past decade to enable atom probe tomography analysis at cryogenic temperatures. The inability to control the local deposition of the metallic precursor from the gas-injection system (GIS) at cryogenic temperature makes the preparation of site-specific specimens by using lift-out extremely challenging in the focused-ion beam. Schreiber et al. exploited redeposition to weld the lifted-out sample to a support. Here we build on their approach to attach the region-of-interest and additionally strengthen the interface with locally sputtered metal from the micromanipulator. Following standard focused-ion beam annular milling, we demonstrate atom probe analysis of Si in both laser pulsing and voltage mode, with comparable analytical performance as a pre-sharpened microtip coupon. Our welding approach is versatile, as various metals could be used for sputtering, and allows similar flexibility as the GIS in principle.