Nanopackaging:
Nanotechnologies in
Microelectronics Packaging
James E. Morris
Department of Electrical & Computer Engineering,
Portland State University, Portland, Oregon, USA
j.e.morris@ieee.org
Nanoparticle Properties (High surface/volume ratio→catalysts, etc)
Nanoparticles → single grain, no
defects
(Mallik)
Criterion:
Fermi Level in
Conduction Band
Aguilera-Granja
Nanotechnology
(2007)
(atoms)
DIFFUSION
Ostwald ripening
Coalescence
2
Sintering
(thermally activated)
Ohring (2002)
(Novikov & Nowottnick, ESTC 2010)
Melting Point Depression:
Normalized curves ~independent of material
Solder: 0.05(273+217) = 24.5K;
TM → 192.5 C for ~5nm
i.e. 5% at 5nm
Sambles, Proc. Royal Soc. (1971) [TEM observations]
(Hongjin Jiang et al, ECTC’07)
[found by DSC]
Temperature (oC)
Melting Point Depression
in Nanoparticle No-Pb
Solders
(Johan Liu et al, EPTC 2008)
220


200
Tm(20)=214oC
Tm(10)=204oC
Bulk
Eq.(1) cal.
Tm(5)=188oC
180
160
 B-sample, Tm=213.92oC
140
 C-sample, Tm=213.75oC
120
0
20
40
Sn-3.0Ag600.5Cu
80
100
120
Particle radius (nm)
SnAg
← ~5% reduction (K) at 5nm
3
Sn-0.4Co-0.7Cu
140
Printed Nanoparticle
Interconnect Deposition
(Felba & Schaeffer) e.g. on flex
Nanoscale Ag on Si, before and after
sintering at 280 (Bai et al)
4
Ag nanoparticle paste : Initially, and after dipping in
methanol for 180s, 600s, 3600s at room temperature
(Wakuda et al)
Nanoparticle Sintering
[Wong et al, ECTC’06]
Surface treatments to avoid agglomeration
(Sun & Wong, ECTC’04)
e.g.
Carboxylate
Amine
Polymer
(Moscicki et al, EMPC 2011)
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ICA
Microvia
Fill
(PWB)
75 C micro/nano Ag
sintering
Das & Egitto
LMP
Cu
Ag
CNT Properties (Wikipedia)
Young’s
Modulus
(Tpa)
Tensile
Strength
(Gpa)
Elongation
at break
(%)
~1 (1-5)
13-53E
16
Armchair
0.94T
126.2T
23.1
Zigzag
0.94T
94.5T
15.6-17.5
Chiral
0.92T
MWNT
0.8-0.9E
150
~0.2
~0.65-1.0
15-50
~0.15
(0.25T)
~3.5
(29.6T)
~2
SWNT
Stainless
steel
Kevlar
T Theoretical
E Experimental
CNT classifications:
Single wall SWNT
Multi-wall MWNT
Armchair
Zigzag
Chiral
SWNTs:
MWNTs:
(Metallic)
(Metallic or
semiconducting)
typ. ⅔ metallic, ⅓ semicond
Grow at ~ 900 C
Metallic
Grow at ~ 700 C (→365 C)
(Mallik)
Nanotubes
Diamond
7
CTE ~ 0
Electrical (Metallic CNT):
Imax CNT > 1000 x Imax Ag/Cu
µCNT ~ 70 x µSi
CNT “ropes” 10-4 Ω.cm
Metals
Solders
Polymers
1
10
100
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1000
Bulk Thermal Conductivity (W/mK)
10000
Open-ended CNTs
for electrical contact
Xiao et al, ECTC
2009, 1811-1815
Oh et al, Nanotechnology,
19 (2008) 495602 (7pp)
CNT Interconnect
(Banerjee, Li, Srivastava NANO 2008)
Inductance Lbundle = Lmagnetic + Lkinetic,
Lkinetic = RLandauer /vf
Quantum capacitance CQ = 1/RLandauervf
(& Ceq< CQ, Celectrostatic)
2
where RLandauer = h/2q = minimum ballistic resistance
and vf = Fermi velocity ≈ 8x105m/s → Lkinetic ≈16nH/μm >>Lmagnetic
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CNTs in TSVs
←Xu et al, Appl Phys Lett (2007)
1
0
15nm MWNTs in 35nm vias
Graham et al, Diamond & Related materials (2004)
TSV reliability issues
(Sinha et al, NMDC 2010)
a)
b)
c)
Cu filled via at normal temperature
Copper expansion can fracture the oxide
layer above
Delamination as a result of thermal cycling
(Metallic) SWNT thermal expansion coefficient
(Jiang et al, J. Eng Materials & Technology, 126 (2004) 265-270)
Pradham, Duan, Liang, Iannacchione,
Nanotechnology, 20 (2009) 245705 (7p)
Aligned SWNTs→
CNT Thermal
Conductivity
Random SWNTs→
Random MWNTs→
←Graphite
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CNT Heat Sink
on Si
(Liu & Wang)
13
Graphene for Thermal Management
(Balandin)
Advancing Microelectronics, 38(4)
July/August 2011, 6-10
Nature Materials, 10 Aug 2011, 569581
FLG heat spreaders
Thermal Conductivity
Balandin, Nature Materials, 10 Aug 2011, 569-581
Health and Environmental Issues & Tort Law:
• Nano-Ag in the environment: aquatic food chain
• Nanoparticles & CNTs in the body
Company responsibility that product meets FDA safety standards
To minimize exposure to litigation, must show:
•Product designed with safety in mind
•Workers educated to possible exposure risks
•Company tracks relevant research, regulations, etc
•NIOSH website Nanoparticle Information Library
•Risks evaluated (in collaboration with others?)
•External statements consistent with internal data/memos
•Affirmative steps to reduce exposures
•Filters, gloves, washing, etc
•Monitors health of workers and consumers
ISO9000 parallel: Must be able to show procedures in place
•If not → negligence! punitive damages!
•Cautions already abound
Canaries: Monitor workers; asbestos problems in factories, not public
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Summary
 Nanoparticles in Microelectronics Packaging
 Carbon Nanotubes in Microelectronics Packaging
 Graphene in Microelectronics Packaging
 Health & Environment (EHS & ELSI)
 Other: Solder, nanowires, nanosprings, contacts, adhesion, ECAs,
nanoelectronics, modeling, etc
References:
1
7

Nanopackaging: Nanotechnologies in Electronics Packaging, J.E. Morris (editor)
Springer (2008)

J.E. Morris, “Nanopackaging,” in Nanoelectronics: Fabrication, Interconnects, and
Device Structures, Kris Iniewski (editor), McGraw-Hill (2010)
9/22/2011