leap tomography and the rapidly expanding world of
TRANSCRIPT
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LEAP® Tomography and the Rapidly Expanding World of Microelectronic Applications
Thomas F. Kelly2007 International Conference on Frontiers of Characterization and
Metrology for NanoelectronicsMarch 29, 2007
www.imago.com
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Imago Contributors External Contributors
• Keith Thompson• David Larson• Jesse Olson• Joe Bunton• Roger Alvis• Rob Ulfig• Dan Lawrence
• Paul Ronsheim, IBM• Brian Gorman, Univ.
North Texas• Sean Corcoran, Intel• Kevin Jones, Sam
Moore, Univ. Florida• David Seidman,
Northwestern Univ.
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Description of Atom Probe Operation
High Voltage ~10 kV
+ -
Needle-Shaped Specimen 50nm radius at apex
~50nm tip 50mm detector = 106 magnification
Evaporation initiated by:• Field Pulsing• or Thermal Pulsing (laser) 3-Dimensional
ReconstructedModel of Specimenz is determined from sequence of evaporation events
Data are collected and interpreted
2D DetectorDetermines x,ycoordinates of atom
Time of Flight (TOF) identifies massTOF~500 ns for LEAP, ∆TOF < 1 ns
Atom Probe = Point projection imaging time-of-flight mass spectrometer
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Application Spaces
Electrical C
onductivity
Thermal Diffusivity
Semiconductorsand Ceramics
Metals
Biological materials
Synthetic Organics
Voltage Pulsing
Laser Pulsing
Finer laser focus
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The Strengths of Atom Probe Tomography
• Mass Analysis– Phase formation and composition identification
• Compositional Imaging– Buried interfaces
• Thin film interfaces, precipitates, grain boundaries
• Structural Imaging– number density, size distribution, …
Mass Spectrum
3D Image
Quantitative 3-D Compositional Imaging at the Atomic Scale with High Sensitivity
Atom Probe Tomography is the highest spatial resolution analytical characterization technique
Spatial Resolution 0.4 nm laterally, < 0.2 nm depth(0.06 nm demonstrated laterally)
Sensitivity ~10 appm
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3000X™
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Specimen Preparation
Microtips™ and the Lift-Out Method
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Top CameraView
Bottom Camera View
Microtips in the LEAP®
• Two types: – Pre-sharpened– Flat top
• Uses:– Depositions (thin films, organics)– Receptacle for liftout
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Extracting Specimens with FIB
Images courtesy of Brian Gorman
Deposit PtMill first trench
Mill second trench
Attach probe and extract sample
Step 1 - Extract the Coupon
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Extracting Specimens with FIB
Perspective view of LEAP microtip coupon
Sample wedge
Microtip post
Pt weld
Attach sample to wedge Remainder of wedge is retracted
With J. Sam Moore and Kevin Jones, University of Florida,Brian Gorman, University of North Texas
Step 2 - Attach Sample Wedge to LEAP Microtip
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Extracting Specimens with FIB
Coupon Mounted on Microtip Sharpened Tip Region of Interest
Total time: 4 hours per 20 specimens
2 µm 2 µm
Step 3 - Final Preparation of Tip
Region of Interest
Region of Interest
Region of
Interest
With J. Sam Moore and Kevin Jones, University of Florida,Brian Gorman, University of North Texas
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Lithographic Critical Features vs. AP Field of View
Source: SIA ITRS and Hitachi Global Storage website
Opening the door to full
device analysis
At the atomic level!!!
Atom Probe Field of View
NiSi
Poly-Si Gate
SiNSiN SiOSiO
SiON
Gate Ox
NiSi NiSiSi
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TEM next-generation transistor
Analysis Volume Approaches Transistor Dimensions
NiSi
Poly-SiGate
SiN SiOSiO
SiON
Gate OxNiSi NiSiSi
LEAP 3000XSi™ with DT200
LEAP reveals dopant distributions
80nm
Red – OGreen - As
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Verification
• Compositional– Compare with known standards– e.g., NIST Standard Reference Material (SRM 2137)
• Spatial– Spatial Distribution Maps™ (SDM™)
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National Institute of Standards & Technology (NIST) Standard Reference Material (SRM)
Dave Simons, NIST
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National Institute of Standards & Technology Standard Sample -Boron Implant
SIMS
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NIST Standard Reference Material – Boron Implant
10 B implant in SiSensitivity of ~1 x 1018 cm-2
is demonstrated1E
+17
1E+18
1E+19
1E+20
050
100150
200250
300
depth (nm)
Concentration (#/cm3)
NIS
T - BLE
AP3000X
- B
NIST Total Dose
1 x 1015 cm-2
LEAP Total Dose
9 x 1014 cm-2
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Tungsten bcc lattice observed Brian Geiser,Imago
Crystal Planes
Spatial Distribution Maps™
Analysis direction
+ + +
Z = 0 Z = ½ Z = 1
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Compositional and Spatial Verification
SiliconArsenicOxygen
1.E+18
1.E+19
1.E+20
1.E+21
010
2030
4050
6070
8090
depth (nm)
A s co n ce n tra tio n (# /cm 3)
0 10 20 30 40 50 60 70
% o xyg e n
Si <200> planes observedMay be used to calibrate depth
Composition calibrated against SIMSDepth calibrated by internal standard w
ith SDM™
LEAP
SIMS
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PolySi/Hafnia High-k Dielectric Stack
Dielectric thicknessO FWHM = 3.7nm, Peak 43 at.%Hf FWHM = 2.5nm
Proximity Histogram Substrate Si 50%: 550 Type 19
0.01
0.1
1
10
100
-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4
[nm]
Con
cent
ratio
n [A
tom
ic %
]
0
5
10
15
20
25 Si O Cl Hf N HO/Hf Ratio
• Paul Ronsheim, IBM• Keith Thompson, Imago• Rob Ulfig, Imago
SubstratePolySi
Hf Si
Hf O
H
N
Substrate
PolySi
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Poly-Si Gate Analysis
0
2
4
6
8
10
12
10 15 20 25distance (nm)
%co
ncen
tratio
n
O H
0
2
4
6
8
10
12
15 20 25 30distance (nm)
%co
ncen
tratio
n
O H
Left Sidewall
Right Sidewall
Kevin S. Jones and John S. Moore, University of FloridaSean Corcorran, Intel and coworkersKeith Thompson and Imago personnel
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Compound Semiconductor NanostructuresAll atoms As atoms In, P atoms
0
1
2
3
4
5
6
7
8
105 115 125depth (nm)
%C
once
ntra
tion
P As Ga In
Brian Gorman, University of North Texas, LEAP 3000X
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0
2
4
6
8
10
12
14
16
0 20 40 60 80 100 120depth (nm)
% c
once
ntra
tion
LEAPSIMS
Summary• Atom probe tomography provides atomic-scale
compositional characterization at high sensitivity in 3D– This is especially useful for characterization of
buried interfaces• Specimen preparation is similar to TEM
– Local electrode enables rapid preparation of multiple samples
• Site-specific Lift-out enables many new applications– Semiconductor device development– Failure analysis– Competitive analysis