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Site-specific Failure Analysis and Reliability Testing of 3D Systems using “Plasma” FIB Richard Young, 1 C. Rue, 1 R. Routh, 1 G. Franz, 2 L.F.Tz. Kwakman, 2 P. Ramm, 3 A. Klumpp, 3 and M.M.V Taklo 4 1 FEI Company, Hillsboro, OR, USA 2 FEI Electron Optics, Eindhoven, The Netherlands 3 Fraunhofer EMFT, Munich, Germany 4 SINTEF, Oslo, Norway [email protected] SEMATECH 3D Interconnect Metrology Workshop: July 13 th , 2010 © FEI Company 2011

“Plasma” FIB

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Page 1: “Plasma” FIB

Site-specific Failure

Analysis and Reliability

Testing of 3D Systems using

“Plasma” FIB

Richard Young,1 C. Rue,1 R. Routh,1

G. Franz,2 L.F.Tz. Kwakman,2

P. Ramm,3 A. Klumpp,3 and M.M.V Taklo4

1FEI Company, Hillsboro, OR, USA

2FEI Electron Optics, Eindhoven, The Netherlands

3Fraunhofer EMFT, Munich, Germany

4SINTEF, Oslo, Norway

[email protected]

SEMATECH 3D Interconnect Metrology Workshop: July 13th, 2010© FEI Company 2011

Page 2: “Plasma” FIB

2

Outline

Introduction to focused ion beams (FIB)

Technologies for faster material removal

Plasma FIB technology

3D integration – performance and reliability drivers

Use case examples:

• Plated bumps

• Stacked die with “TSV” and “SLID” bond technology

• Anisotropic conductive adhesive for wafer-to-wafer bonding

Summary

© FEI Company 2011

Page 3: “Plasma” FIB

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What a focused ion beam (FIB) system can do:

Remove Material

• Sample is sputtered

where beam is scanned,

sometimes with a

reactive gas

Add Material

• A gas is decomposed where

beam is scanned

Form an Image

• Secondary electrons or ions are

collected to assemble an image

© FEI Company 2011

Page 4: “Plasma” FIB

4

Focused ion beam sample prep

Excellent for site-specific sample preparation

• Localized – positioning to nm level

- Leave rest of device intact

- Multiple locations on single device

• Any orientation

• No mechanical shock or tearing/smearing

Generally uses gallium liquid metal ion source (LMIS)

Typical beam current range 1 pA to 20-65 nA

• ~103 μm3/min for silicon at 60 nA

• Short prep times for sections a few 10s of μm on a side

• 3D IC technology/packaging sections often > 100 μm

• Therefore, require new techniques focused on

throughput and efficiency300 µm wide

>12 hours with 65nA Ga-FIB

© FEI Company 2011

10 µm wide

20 mins (Ga-FIB)

Page 5: “Plasma” FIB

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Enhancing FIB capabilities

High-speed silicon removal with XeF2

• Gas assisted etching (e.g. I2, XeF2, Cl2)

• Enhancement varies by material (1-15X)

• Special case: XeF2 + Si → 5-10 μm3/min

• Already used in backside circuit edit for “trenching”

• Limited mainly to bulk silicon removal

Larger beam currents with Ga LMIS

• Latest systems already use 65 nA from 21 nA

New source technology for higher beam currents (> 1 μA)

• Inductively coupled plasma (ICP) source

• Improvement > 20X over Ga-FIB

© FEI Company 2011

Page 6: “Plasma” FIB

6

0.001

0.01

0.1

1

10

100

0.001 0.01 0.1 1 10 100 1000 10000

Spo

tsiz

e [µ

m]

Beam Current [nA]

Xe Plasma

Ga LMIS

Why Plasma FIB: 20x faster than current FIBs

High volume milling / high beam

current

Ga-FIB loses size advantage to

plasma source as beam current

goes above 50-60 nA

Xe has high sputter yield, high

brightness, and low energy spread

No Ga contamination

A system that provides unique and fast ion milling capabilities

for rapid cross sectioning of features from 50 to 1000 microns.

© FEI Company 2011

Page 7: “Plasma” FIB

7

Inductively coupled plasma (ICP) ion source

• Gas flows into plasma cell

• Helical antenna couples energy into plasma cell

• Electrons removed from atoms to form Xe+ ions

• Extraction optics accelerate ions into FIB column

© FEI Company 2011

Page 8: “Plasma” FIB

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Comparison of FIB sources

LMIS

ICP

© FEI Company 2011

Page 9: “Plasma” FIB

9

Outline

Introduction to focused ion beams (FIB)

Technologies for faster material removal

Plasma FIB technology

3D integration – performance and reliability drivers

Use case examples:

• Plated bumps

• Stacked die with “TSV” and “SLID” bond technology

• Anisotropic conductive adhesive for wafer-to-wafer bonding

Summary

© FEI Company 2011

Page 10: “Plasma” FIB

10 © FEI Company 2011

Page 11: “Plasma” FIB

11

Cross-sectioned bump

•Bump test wafer (Courtesy SEMATECH)

•80 µm wide and 100 µm tall

•Cross-sectioned and imaged in 20 min.

© FEI Company 2011

Page 12: “Plasma” FIB

12

Stacked die with “TSV” and “SLID” bond

technology

© FEI Company 2011

Three-die reliability test chip

•TSV: Through silicon via (Cu or W)

•SLID: Solid-liquid interdiffusion

bonding (Cu-Sn-Cu)

•IMC: intermetallic compounds

Ref: P. Ramm, A. Klumpp, G. Franz, and

L. Kwakman, Proc. IMAPS Device

Packaging Conf., Scottsdale, Arizona,

2011

Page 13: “Plasma” FIB

13 © FEI Company 2011

Page 14: “Plasma” FIB

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Cross sectioning three-die stack

© FEI Company 2011

Page 15: “Plasma” FIB

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Details of the SLID bonding (Cu-Sn-Cu)

© FEI Company 2011

Page 16: “Plasma” FIB

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Anisotropic conductive adhesive for Wafer-

to-Wafer bonding

© FEI Company 2011

Ref: M.M.V. Taklo, T. Bakke, H.R. Tofteberg, L.G.W. Tvedt and H. Kristiansen, Proc. IMAPS Device Packaging Conf.,

Scottsdale, Arizona, 2011

Metal coated polymer spheres (4 µm diameter) Electrical contacts

Page 17: “Plasma” FIB

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Anisotropic conductive adhesive for W2W

© FEI Company 2011

Box: 200 x 50 x 600 μm3

Time: 30 min

Page 18: “Plasma” FIB

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Summary

3D IC technology needs metrology and root cause analysis down to the

sub-micron level for development and failure analysis

• But it takes too long with traditional Ga-FIB

Plasma FIB technology brings site specific advantages of Ga FIB to

chip/package scaled problems

• More than 20x faster than traditional FIB

• Capable of high-precision final cuts and high-resolution (sub-30 nm) imaging

• Provides faster development feedback and failure analysis

Acknowledgements: A part of the work has been performed in the project JEMSiP_3D, which is funded

by the Public Authorities in France, Germany, Hungary, The Netherlands, Norway and Sweden, as well as

by the ENIAC Joint Undertaking.

© FEI Company 2011