Depth and lateral resolution of laser-assisted atom probe microscopy of silicon revealed by isotopic heterostructures

We report on a direct comparison of the depth and lateral resolution of the current state-of-the-art laser-assisted atom probe microscopy analysis of single-crystalline silicon. The isotopic heterostructures composed of 5-15 nm-thick Si-28- and Si-30-enriched layers were measured to reconstruct three-dimensional images of Si-28 and Si-30 stable isotope distributions in the surface perpendicular and parallel directions for the analysis of the depth and lateral resolution, respectively. The decay length experimentally obtained for the lateral direction is only about twice longer than in the direction, meaning that the lateral resolution is higher than obtained by secondary ion mass spectrometry. (C) 2011 American Institute of Physics. [doi:10.1063/1.3544496]