Wisconsin Alumni Research Foundation

Cameca Instruments, Inc.

Imago Scientific Instruments Corporation

Lockheed Martin Idaho Technologies Company

Thomas F Kelly

Scott A Wiener

Steven L Goodman

Joseph Hale Bunton

Patrick Paul Camus

Richard L Martens

Louis M Holzman

Tye Travis Gribb

Jon J McCarthy

John E Flinn

Daniel Robert Lenz

Derrick C Mancini

Sateeshchandra S Bajikar

Mark Ronald Levesque

David J Larson

In an atom probe having a vacuum chamber containing a specimen mount and a detector for receiving ions emitted from the specimen, a high vacuum subchamber is provided about the specimen mount, with an aperture in the subchamber allowing passage of emitted ions to the detector. The high vacuum subchamber may be pumped to higher vacuum (lower pressure) than the vacuum chamber, and so long as the pressure in the vacuum chamber is below about 10Pa, very little gas diffusion takes place through the aperture, allowing higher vacuum to be maintained in the subchamber despite the aperture opening to the chamber. The higher vacuum in the subchamber about the specimen assists in reducing noise in atom probe image data. The aperture may conveniently be provided by the aperture in a counter electrode, such as a local electrode, as commonly used in atom probes.

Atom probe with vacuum differential

The present invention is directed generally toward atom probe and TEM data and associated systems and methods. Other aspects of the invention are directed toward combining APT data and TEM data into a unified data set. Other aspects of the invention are directed toward using the data from one instrument to improve the quality of data obtained from another instrument.

3D atomic scale imaging methods

An atom probe includes a detector which registers the time of flight of ions evaporated from a specimen, as well as the positions on the detector at which the ions impact and the kinetic energies of the ions. The detected position allows the original locations of the ions on the specimen to be mapped, and the times of flight and kinetic energies can be spectrally analyzed (e.g., binned into sets of like values) to determine the elemental identities of the ions. The use of kinetic energy data as well as time of flight data can allow more accurate identification of composition than where time of flight data are used alone, as in traditional atom probes.

Methods and devices for improving atom probe detector performance

The present invention relates generally to atom probes, atom probe specimens, and associated methods. For example, certain aspects are directed toward methods for analyzing a portion of a specimen that includes selecting a region of interest and moving a portion of material in a border region proximate to the region of interest so that at least a portion of the region of interest protrudes relative to at least a portion of the border region. The method further includes analyzing a portion of the region of interest. Other aspects of the invention are directed toward a method for applying photonic energy in an atom probe process by passing photonic energy through a lens system separated from a photonic device and spaced apart from the photonic device. Yet other aspects of the invention are directed toward a method for reflecting photonic energy off an outer surface of an electrode onto a specimen.

Atom probes, atom probe specimens, and associated methods

A laser atom probe () situates a counter electrode between a specimen mount and a detector (), and provides a laser () having its beam () aligned to illuminate the specimen () through the aperture () of the counter electrode (). The detector, specimen mount (), and then be pulsed to bring the specimen to ionization. The timing of the laser pulses may be used to determine ion departure and arrival times allowing determination of the mass-to-charge ratios of the ions, thus their identities. Automated alignment methods are described wherein the laser is automatically directed to areas of interest.

Laser atom probe

Methods of sampling specimens for microanalysis, particularly microanalysis by atom probe microscopy, include steps of forming a study specimen in a first study object (as by use of focused ion beam milling); removing the study specimen from the study object; situating the study specimen on a second study object; and microanalyzing the study specimen. Where the first study object is of particular interest for study, the study specimen may be taken from a functional portion of the first study object so that microanalysis will provide information regarding this functional portion. Where the second study object is of particular interest for study, the second study object may be subjected to manufacturing processes (e.g., deposition of layers of materials) after the study specimen is situated thereon so that the study specimen will provide information regarding the results of the manufacturing process. The study specimen may have study regions formed thereon which are particularly suitable for study by atom probes, e.g., regions bearing raised protrusions, at virtually any point during the process, thereby greatly enhancing the speed and efficiency of specimen preparation.

Methods of sampling specimens for microanalysis

Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains.

Strengthening of metallic alloys with nanometer-size oxide dispersions

An atom probe provides rapidly pulsed field evaporation/desorption of ions from a tip utilizing a local extraction electrode positioned closely adjacent to the tip. A bias potential is applied between the tip and the local extraction electrode which provides an electric field at the tip which is less than but near the field intensity required for field evaporation of ions. Additional potential is applied between the tip and the extraction electrode in relatively low over-voltage pulses to obtain field evaporation of ions without substantially accelerating the ions. The ions extracted from the tip by the sharply defined pulses pass through an aperture in the extraction electrode and are accelerated by a large potential difference between the tip and a detector spaced from the tip and the local extraction electrode. An intermediate acceleration electrode may be positioned between the extraction electrode and the detector, with the acceleration electrode having an aperture therein to pass ions therethrough to the detector. The acceleration electrode is maintained at a higher potential with respect to the tip than the extraction electrode, and may be maintained at the same potential as the detector so that ions passed through the acceleration electrode coast to the detector. The use of relatively low voltage pulses to obtain evaporation of ions permits rapid repetition of the pulses, on the order of hundreds of thousands of pulses per second, to allow rapid accumulation of atom probe data.

High mass resolution local-electrode atom probe

A position sensitive detector has one or more wedge-and-wedge anode units, each of which has four electrodes on a planar surface arranged in a plurality of sets of four wedge-shaped electrode elements each, with the sets extending across the anode unit. Two of the electrode elements become progressively wider from set to set from one side of the anode unit to the other, while the other two electrode elements become progressively narrower. The respective electrode elements in each set are electrically connected together to complete the four electrodes. The charge measured on each of the four electrodes can be utilized to determine the X and Y coordinates of an event which results in a charge cloud impacting the anode, with redundant information available from the four electrodes. The coordinates calculated using charge information from any three of the electrodes can be compared with information calculated from the charge measured from the fourth electrode and two of the other electrodes, and the two sets of calculations can be compared. If each set of calculations does not yield the same result, two or more events have occurred simultaneously at different positions, and the measured data can be rejected to avoid erroneous data. The electrodes of large arrays of such anode units can be readily connected together to cover a large detector area with a minimal number of data output lines required, and with the capability of determining the position of simultaneous events by taking advantage of the redundant information available from each anode unit.

Position sensitive detector providing position information with enhanced

Atom probe apparatus includes an emission tip from which atoms can be evaporated in atomic emission events, a position sensitive detector for detecting the position and timing of the charge cloud resulting from atomic emission events, and a pulse heating beam for heating the emission tip in short pulses to evaporate atoms essentially one at a time from the emission tip. The heating beam may be formed as an electron beam from an electron gun which is directed to the tip and scanned rapidly back and forth across the tip to be incident upon the tip for short periods of time as the beam is scanned back and forth. The beam may further be produced as a chopped beam of electrons by scanning the beam back and forth across a slit in an aperture plate so that only pulses of electrons pass through the plate as the beam passes across the slit. The electrons passing through the slit are then focused and directed to the tip. The tip may also be heated by light from a pulsed source such as a laser which is passed through a reflecting Schwarzschild objective and focused onto the tip in pulses to provide excitation by light photons. The position sensitive detector, which may include a microchannel plate backed by a position sensitive wedge and strip detector, determines both the time of arrival of a charge pulse from an atomic emission event and the relative position of the charge cloud at the point where it impacts upon the detector. The detector may also be formed as a three-level, trigonal array of pads which allows both one and two atomic events per heating pulse to be resolved.

High-repetition rate position sensitive atom probe

An X-ray detector efficiency standard is formed of multiple spherical particles of various materials distributed over the surface of a substrate. The particles are preferably formed of pure materials, such as pure elements and stoichiometric compounds, having characteristic X-ray emission energies which span a range sufficient to determine the efficiency of the X-ray detector substantially over its operating range. The spherical particles may be formed by an electrohydrodynamic spraying process and have a diameter preferably in the range of 10 nanometers to 1 micron.

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Madison, WI, United States of America

Thomas F Kelly