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

2© IMEC 2013 / CONFIDENTIAL

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

Acknowledgment

Imec processing groups & Core partners

AP : Sebastian Koelling, Ajay Kambham, Arul Kumar, Matthieu Gilbert

SSRM : Jay Mody, Andreas Schulze, Pierre Eyben, Kristof Paredis