title: In situ site-specific specimen preparation for atom probe tomography.
abstract: Techniques for the rapid preparation of atom-probe samples extracted directly from a Si wafer are presented and discussed. A systematic mounting process to a standardized microtip array allows approximately 12 samples to be extracted from a near-surface region and mounted for subsequent focused-ion-beam sharpening in a short period of time, about 2h. In addition, site-specific annular mill extraction techniques are demonstrated that allow specific devices or structures to be removed from a Si wafer and analyzed in the atom-probe. The challenges presented by Ga-induced implantation and damage, particularly at a standard ion-beam accelerating voltage of 30 keV, are shown and discussed. A significant reduction in the extent of the damaged regions through the application of a low-energy "clean-up" ion beam is confirmed by atom-probe analysis of the damaged regions. The Ga+ penetration depth into {100} Si at 30 keV is approximately 40 nm. Clean-up with either a 5 or 2 keV beam reduces the depth of damaged Si to approximately 5 nm and <1 nm, respectively. Finally, a NiSi sample was extracted from a Si wafer, mounted to a microtip array, sharpened, cleaned up with a 5 keV beam and analyzed in the atom probe. The current results demonstrate that specific regions of interest can be accessed and preserved throughout the sample-preparation process and that this preparation method leads to high-quality atom probe analysis of such nano-structures.
authors.affiliation: Imago Scientific Instruments Corporation, 6300 Enterprise Lane, Suite 100, Madison, WI 53719, USA. kthompson@imago.com
authors.forename: K
authors.initials: K
authors.lastname: Thompson
authors.forename: D
authors.initials: D
authors.lastname: Lawrence
authors.forename: D J
authors.initials: DJ
authors.lastname: Larson
authors.forename: J D
authors.initials: JD
authors.lastname: Olson
authors.forename: T F
authors.initials: TF
authors.lastname: Kelly
authors.forename: B
authors.initials: B
authors.lastname: Gorman