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TRANSCRIPT
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FIB applications in the nano‐technology world
Hugo Benderimec, Leuven, Belgium
EFUG 2013
30/9/13
MCASA : Chris Drijbooms, Patricia Van Marcke, Jef Geypen,
Pieter Lagrain, Olivier Richard, Paola Favia
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OUTLINE
Introduction
FIB as a preparation tool for nano-device analysis
▸ FIB/SEM imaging
▸ TEM specimen preparation
▸ Atomprobe needle preparation
▸ SSRM marking and backcontacts
Conclusions
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FROM MICRO-TO NANO-
ELECTRONICS
CMOS scaling :
• Decrease of 3D-dimensions
• New and more materials
• New device concepts
Interconnect :
• Decrease on chip
• Stacked dies : increase
dimensions
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INTRODUCTION : TYPICAL STRUCTURES
GatepFET
nFET
nFET
Fins 45 nm pitch
Gates
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110 nm
28nm
FIB / SEM PARALLEL FINS
Start of FIN
Through FIN
Spacing between FIN
- Position / slicing accuracy
- Contamination SEM
- Slow in-situ plasma clean
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TEM PREPARATION PARALLEL FIN / GATE
HM
poly
gate
above
fin
HM
poly
gate
50 nm
thick
specimen
50 nm
thick
specimen
The colored boxes indicate the approximate volume
probed in the other specimen cross-section direction
epi
cap
STI
gate
30nm
fin
11nm
- Position accuracy
- Projection overlaps
- Small thickness/damage
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PARALLEL FIN
30 kV FIB
30 kV + 5kV FIB
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SRAM CELL
Specimen
Specimen
Active Fin gates L1 = metal on silicide L2 = metal vias Cu metal lines
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SRAM PARALLEL/ACROSS FINS
SEM final specimen
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SPECIMEN THICKNESS30kV older FIB 30+5kV newFIB
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CURTAINING
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SUBSTRATE SIDE THINNING
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SUBSTRATE SIDE MILLING
Si
InP
InAs
Ge
Curtaining moved to the upper side
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THICKNESS CONTROL
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ATOM PROBE PREPARATION
Sebastian Koelling, PhD 2011, KULeuven
- Adhesion on the metal wire
- Capping
- Shape/size
- FIB damage
- Ageing
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ATOM PROBE TIP –TEM
73º75º
tip radius 155 nm
5kV amorphous layer ~ 5 nm
AP : Arul Kumar
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SSRM : SCANNING SPREADING RESISTANCE MICROSCOPYOptions :▸ Cleaved samples : backcontact and
marks without milling/damaging the
cleaved face
▸ Cleaning mill of cleaved face : - low kV minimum damage and Ga
implantation
- from substrate side to avoid
curtaining
Backcontact position :▸ For small structures (fins) : as close
as possible to the cleaved face and
with low kV finishing/Pt for low
backcontact resistance.
▸ 3D devices
Conductive diamond probe
Backcontact
Active dopant mapping
Andreas Schulze, PhD KULeuven
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SSRM BACKCONTACT / MARKS
Marks 30 kV
Trench 30kV + additional 5 kV
Pt fill 5 kV
Pt line/pad 5 kV
Requirements :
• No FIB imaging on the cleaved face
• 5kV final milling trench and Pt fill
• Backcontact
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SSRM : BACKCONTACT DISTANCE
Backcontact at 100 µm
Bulk resistance dominates
Backcontact at 1 µm
Spreading resistance dominates
Bulk resistance Fin width 30 nm 100 nm 900 nm
Tip radius
J Mody, J. Vac. Sci. Technol B 26 351 (2008)
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2kV 53°
SSRM STAIRCASE 30 kV 5 kV 2 kV
5kV 53°
30 kV
5kV
2kV
Staircase
dopant
profile
P. Eyben et al
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CONCLUSIONS
FIB as preparation tool for nanodevices :
Dual beam imaging
TEM preparation
Atom probe preparation
SSRM preparation
(Device edit)
TSV / stacked die analysis : new FIB concepts needed :
plasmafib, laser ablation.
Key requirements
- Low energy milling
- No curtaining
- Position accuracy
- Excellent SEM image
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Acknowledgment
Imec processing groups & Core partners
AP : Sebastian Koelling, Ajay Kambham, Arul Kumar, Matthieu Gilbert
SSRM : Jay Mody, Andreas Schulze, Pierre Eyben, Kristof Paredis