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www.cameca.com
A Brief History of Atom Probe
Thomas F. Kelly and John A. PanitzPre-meeting Congress, M&M 2016
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Ancestry of the Modern Atom Probe
July 24, 2016A Brief History of Atom Probe 2
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Erwin Wilhelm Müller
July 24, 2016A Brief History of Atom Probe 3
Photograph of Professor Erwin W. Müller (1911-1977): Father of High Field Nanoscience
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Field Electron Emission Microscopy
July 24, 2016A Brief History of Atom Probe 4
E. W. Müller, Z. Phys. 120 (1943) 270
Fluo
resc
ent S
cree
n
- electron
E +
1935
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Field Electron Emission Microscopy
■ Field electron emission microscopy (FEEM) was developed as a point projection microscope
■ FEEM patterns showed clear crystallographic information■ Ba atoms and phthalocyanine molecules were observed on
W needles with FEEM■ Image resolution improved through the late 1940’s■ Müller sought to resolve atoms with FEEM■ Eventually it was concluded that FEEM would resolve no
better than ~2 nm■ Field desorption (and evaporation?) was shown in 1941
July 24, 2016A Brief History of Atom Probe 5
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Field Ion Microscopy
July 24, 2016A Brief History of Atom Probe 6
Erwin Müller at Penn State
• FEEM tips were routinely cleaned by reversing the bias
• Practitioners of FEEM noticed:• Field ions were emitted during
reverse bias• Müller sought, and found, a way
to increase the signal of field ions: H, He gas
• Intensity of field ion signal varied with gas pressure
• In early 1950s, this was pursued for imaging the tip surface
• Atoms at ledges were seen
• Early field ion images (FIM) had higher resolution than FEEM
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Field Ion Microscopy
July 24, 2016A Brief History of Atom Probe 7
First images ever of atoms (on ledges of tip surface): Summer 1951, MüllerFirst atomically resolved lattice on surface: October 11, 1955, Bahadur and Müller
Fluo
resc
ent S
cree
n
+ ion
+ E
1951
Gas supply
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Imaging Crystal Defects in FIM■ Surface atoms and
defects are visible in FIM■ E.g. Self-interstitial
atoms produce large image in FIM
July 24, 2016A Brief History of Atom Probe 8
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Vacancies imaged in FIM!■ Vacancies observed■ Knock-on damage
cascades were mapped by cinematography of FIM
July 24, 2016A Brief History of Atom Probe 9
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1960s FIM
July 24, 2016A Brief History of Atom Probe 10
FIM & Field Evaporation
Movie
40 K Tungsten NeedleHelium GasPhosphor Screen
Best Imaging Voltage
Slight Laser Heating
Field Evaporation
Adsorbed gas atoms ⇒ field ion imageSpecimen atoms ⇒ atom probe Movie Courtesy Baptiste Gault
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3D FIM Comes to Life!
July 24, 2016A Brief History of Atom Probe 12
• 100% of atoms positioned
• High precision on atom locations
• Crystal structure and defects readily visible
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Compositional Contrast in FIM
July 24, 2016A Brief History of Atom Probe 13
In this field ion micrograph of boron-doped nickel aluminide (Ni3Al), the bright dots are individual boron atoms that have segregated to a grain boundary (arrowed).
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The Atom Probe
July 24, 2016A Brief History of Atom Probe 14
Mueller, Panitz, McLane, Rev. Sci. Instrum. (1968) vol. 39, p. 83.
John A. Panitz
Müller sought a way to identify atoms in the ■specimenBarofsky was asked to built a magnetic sector ■mass spectrometer
He later suggested that they should try ToF■
Panitz was assigned the job■How to detect single atoms? Never been done■
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Much of the following from Panitz 2014
54th International Field Emission SymposiumAtom Probe Tomography and MicroscopyStuttgart, Germany 2014
July 24, 2016A Brief History of Atom Probe 15
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The Müller Group ~ 1968
July 24, 2016A Brief History of Atom Probe 16
Names in bold are part of the atom probe effort
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Original Atom-Probe Field Ion Microscope
July 24, 2016A Brief History of Atom Probe 17
1967
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Single Atom Detection Was Invented
July 24, 2016A Brief History of Atom Probe 18
Photograph of oscilloscope screen
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Data File: Oscilloscope Trace
July 24, 2016A Brief History of Atom Probe 19
Atom Hit
Polaroid picture of oscilloscope screen
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First Publication on Atom Probe
July 24, 2016A Brief History of Atom Probe 20
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The Second Atom Probe - 1968
July 24, 2016A Brief History of Atom Probe 21
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■ Tip tilting not needed■ Flight distance 11.38 cm to center■ Observe field ion image or field desorption image■ Mass analyze all atoms within a field of view
July 24, 2016A Brief History of Atom Probe 23
Imaging Atom Probe: the Progenitor of Atom Probe Tomography
MRP of ■ 14 was achieved!
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Imaging Atom Probe 2.0: Curved MCPs
July 24, 2016A Brief History of Atom Probe 24
Tip at center of MCP ■curvatureAll parts of detector ■have same flight lengthHigh mass resolution ■over entire field of viewTomographic imaging ■possible
Detector technology for recording each ion impact position was not yet invented
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Field Desorption Images of Single Specie
July 24, 2016A Brief History of Atom Probe 25
■ Time gate on MCPs
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Pulsed Laser Atom Probe■ A laser was adapted to
the Imaging atom probe at Sandia Laboratories
■ First time non-metals were atom probed
■ Laser pulsing has become the dominant pulsing mode in APT
July 24, 2016A Brief History of Atom Probe 26
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PLAP data - Molybdenum
■ Flight path was not optimized
■ No correction for flight distance across detector
■ Demonstrated laser pulsing for metals, insulators
■ Correct isotopic abundances
July 24, 2016A Brief History of Atom Probe 27
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New Groups Develop – University of Oxford
July 24, 2016A Brief History of Atom Probe 28
Professor George Smith
Early atom probe at Oxford
Congratulations to GeorgeMSA Distinguished Scientist Award
First atom probe expert
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The Vacuum Generators APFIM 100
Developed in conjunction with ■Smith et al. at OxfordFirst commercial atom probe■
July 24, 2016A Brief History of Atom Probe 29
1975
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The Position-Sensitive Atom Probe
■ Adapted a Wedge-and-Strip detector from astronomy to a VG APFIM 100
■ 1988 Fall MRS presented by George Smith
■ First operational 3DAP
July 24, 2016A Brief History of Atom Probe 30
1988
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The Position-Sensitive Atom Probe (PoSAP)
July 24, 2016A Brief History of Atom Probe 31
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The Commercial PoSAP
July 24, 2016A Brief History of Atom Probe 32
Manufactured by Kindbrisk (Oxford NanoScience)
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Tomographic Atom Probe
July 24, 2016A Brief History of Atom Probe 33
D. Blavette, A. Bostel, J. M. Sarrau, B. Deconihout, and A. Menand: An atom-probe for three dimensional tomography. Nature 363:432–435 (1993).
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TAP Detector
July 24, 2016A Brief History of Atom Probe 34
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Electron-Beam-Pulsed Atom Probe
Thermal pulsing can be route to high repetition rates ■Need to heat very small volumes for rapid cooling■
Needed for high mass resolving power■
Electron beams can be focused to very small diameter■■ ~100 nm heated volumeSpecimen in atom probe is positive electrode■
Thermal pulsing with electron beam■July 24, 2016A Brief History of Atom Probe 35
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Atom Probe and (S)TEM
Electron beam pulsing and ■atom probe naturally suggest imaging during analysisThere are many ■advantages of having a TEM image of the specimen
July 24, 2016A Brief History of Atom Probe 36
Kelly, 1990 IFES meeting, Albuquerque
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Electron-Beam-Pulsed Atom Probe
July 24, 2016A Brief History of Atom Probe 37
Larson, Camus and Kelly, Applied Surface Science 67 (1993) 473.
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The Atom Probe Microscope
July 24, 2016A Brief History of Atom Probe 38
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There were Challenges to overcome
With Cryopump on■
July 24, 2016A Brief History of Atom Probe 39
Vibration• -free coolingField emission from electrode•
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Scanning Atom Probe
Nishikawa, O., Kimoto, M., Applied Surface Science (1994) vol. 76, pp. 424-430.
July 24, 2016A Brief History of Atom Probe 40
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Origins of Local Electrode Atom ProbeBasic conundrum: ■■ 3DAP is superlative analytical tool but■ 3DAP of 1990 is too slow to be practical (1 atom/s)
The field of view was limited to about ■ 20 nm
Scanning Atom Probe used an aperture electrode close to ■specimenField emitter arrays had demonstrated field enhancement ■factors of 10 relative to remote electrodeLower voltage pulsers can achieve much higher repetition ■ratesTwo key results: ■
Use local electrode to obtain high data rates■Relative reduction in energy spread can be compensated by post ■acceleration => high mass resolution over full field of view
July 24, 2016A Brief History of Atom Probe 41
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Local Electrode
July 24, 2016A Brief History of Atom Probe 42
Enables:Analysis of microtips and needlesHigh data collection ratesLarge field of view
Local Electrode
Specimen
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Microtips™ in the LEAP®
Local Electrode
July 24, 2016A Brief History of Atom Probe 43
Microtip Array
1 mm
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Solid Model of Alpha Prototype
July 24, 2016A Brief History of Atom Probe 44
Cryopump
Specimen and local electrode
Detector
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Alpha Prototype to LEAP 3000 – Circa 2001
July 24, 2016A Brief History of Atom Probe 45
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There Are Many LEAP Models Anticipated
July 24, 2016A Brief History of Atom Probe 48
Quantum LEAPLEAP FrogLEAP of FaithLambeau LEAP
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EIKOS IS Atom Probe Tomography
July 24, 2016
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Focused Ion Beam: General Liftout Method
50
a) b)
c) d)
e) f)
1
23
All scale bars are 5 μmA Brief History of Atom Probe July 24, 2016
All scale bars are 1 μm (except f which is 200nm)
c) d)
e) f)
a) b)
David Larson led the way on FIB preparation of specimens
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The ATOM Project
O. Krivanek et al., Ultramicros. 108 (2008) 179.
Position–Sensitive Detector
Side-entry liquid He sample stage
STEM+LEAP
July 24, 2016A Brief History of Atom Probe 51
Build objective lens assembly with atom probe inside
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July 24, 2016A Brief History of Atom Probe 52
Project Tomo
Build objective lens ■assembly with atom probe inside
TEM+LEAP
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Specimen Holder for Project TOMO
Electron Beam
Evaporated Ions
July 24, 2016A Brief History of Atom Probe 53
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EELS
Properties
Diffraction
Atomic Structure
Computed Image
Atom Probe
STEM
Structure-Properties Microscopy
Electronic StructureElectronic Structure
AST
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In the History of Microscopy, We are at an Inflection Point
July 24, 2016A Brief History of Atom Probe 55
Log
(Len
gth
Scal
e of
Kno
wle
dge)
Today Time
Telescopes
Microscopes
Macro
Micro
Mega
Human eye
1600Prehistory
Inflection point
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The History of Microscopy
■ The history of microscopy is the pursuit of learning “more and more about less and less”
■ We have reached the atomic scale■ This marks an inflection point
■ The future of microscopy will be the pursuit of learning “more and more about more and more”
July 24, 2016A Brief History of Atom Probe 56
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Ancestry of the Modern Atom Probe
July 24, 2016A Brief History of Atom Probe 57
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We’ve made progress: From Müller
July 24, 2016A Brief History of Atom Probe 58
1951- FIM 1967 - APFIM1935 - FEM
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To Commercial Atom Probes
1990- PoSAP 2016 – LEAP 5000, EIKOS1975 – VG APFIM 100July 24, 2016A Brief History of Atom Probe 59