Spatial Resolution in Atom Probe Tomography

Abstract

This article addresses gaps in definitions and a lack of standard measurement techniques to assess the spatial resolution in atom probe tomography. This resolution is known to be anisotropic, being better in the depth than laterally. Generally the presence of atomic planes in the tomographic reconstruction is considered as being a sufficient proof of the quality of the spatial resolution of the instrument. Based on advanced spatial distribution maps, an analysis methodology that interrogates the local neighborhood of the atoms within the tomographic reconstruction, it is shown how both the in-depth and the lateral resolution can be quantified. The influences of the crystallography and the temperature are investigated, and models are proposed to explain the observed results. We demonstrate that the absolute value of resolution is specimenspecific. 2/23

Advances in the reconstruction of atom probe tomography data

“…The spatial accuracy of atom probe tomography has been under scrutiny through the past few years in both high-voltage pulsing [11,12] and laserpulsing modes [13,14]. It was proposed that, in pure metals, the lateral resolution is limited by a combination of surface-diffusionrelated processes and trajectory aberrations, while the sequence in which atoms are field evaporated from the specimen surface underpins the in-depth resolution.…”

Impact of laser pulsing on the reconstruction in an atom probe tomography

“…In doing so, we utilise a novel approach developed recently for the calibration of reconstruction parameters [21,22]. These methods have been used to investigate the influence of several experimental parameters, such as the temperature or the electrostatic environment, on the quality of tomographic reconstruction and the spatial resolution of the technique in voltage pulsing mode [23,24]. Using similar approaches, a series of atom probe analyses on pure aluminium have been undertaken to investigate the impact of varying laser power on the two main reconstruction parameters, the image compression factor and field factor, and on the evolution of the specimen apex average shape.…”

Atom probe tomography in nanoelectronics

“…A major advantage of APT is its quantitativity combined with its high spatial resolution (0.1 nm in depth, a few nm laterally) [16,17]. The local composition in a small selected region of the analyzed volume (a few nm 3 ) is simply derived from the number of atoms of each species.…”