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Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
*Joohee Kim, *Eakhwan Song, *Jeonghyeon Cho, *Jun So Pak,
**Junho Lee, **Hyungdong Lee, **Kunwoo Park and *Joungho Kim
* Korea Advanced Institute of Science and Technology (KAIST)
** Hynix Semiconductor Inc.
2010. 6. 17.
Agilent Measurement Forum 2010
Through Silicon Via (TSV) Equalizer
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Contents
2
Introduction
Analysis of loss mechanism of a TSV
Proposed TSV Equalizer
Simulation-based Verification of the Equalization Performance of the
Proposed TSV Equalizer
Conclusion
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
PCB
Through Silicon Via (TSV) in 3-dimensional Integrated Circuits
3
Through Silicon Via (TSV) is a vertical interconnection method
between chips in 3-dimensional integrated circuits.
Package
Stacked
Dies
[ 3-dimensional Integrated Circuits ]
Interposer
Interposer
Package
Die
Through Silicon Via
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
A Through Silicon Via Structure on Double-sided Silicon Substrate
4
1111111111111 TSV Double-sided
Silicon Substrate
Underfill
Insulation layer
Inter-metal Dielectric
Underfill Metal (M1,M2) Bump
Inter-metal Dielectric
Bump Cu SiO2 Si
Cinsulator GSi sub
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Frequency-dependent Loss of Through Silicon Via
5
1 -6
-5
-4
-3
-2
-1
0
10 20 0.1
Capacitive
region Resistive
region
Cu SiO2 Si
Leakage current
Frequency
dependent term
Loss term
Cinsulator GSi sub
Tra
nsm
issio
n c
oeffic
ient
(S21)
[dB
]
Frequency [GHz]
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Cinsulator Cinsulator
High Speed Signal Performance Degradation caused by TSV
6 Time (ps)
0 100 80 20 40 60 -0.25
0.25
0 V
olta
ge
(V
)
0 100 80 20 40 60 -0.25
0.25
0
Vo
lta
ge
(V
)
Time (ps)
The Eye is Closed!
We Need an Equalizer !
Ground
TSV Signal
TSV
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Scalable Equivalent Circuit Model of a TSV
7
Cinsulator Cinsulator
Cinsulator Cinsulator Bump Bump
Signal
TSV
Ground
TSV
Structural Parameters
TSV diameter : d
TSV-to-TSV pitch : p
SiO2 thickness : t
Height : h
Bump diameter : D
Equations
Cinsulator (d,h,t)
CSi sub (d,h,p,t)
CBump (p,D)
GSi sub (d,h,p,D)
RTSV (d,h)
LTSV (d,h,p)
Cinsulator Cinsulator
Cinsulator Cinsulator
GSi sub
CSi sub
RTSV RTSV
LTSV LTSV
CBump
CBump
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Scalable Equivalent Circuit Model of a TSV
8
d
)d/
td/(
h)επ(
L
)a
b(
εεπ C r
insulator
2
2ln
42
ln
2
0
0
Cinsulator (d,h,t) : SiO2 insulator capacitance
CSi sub (d,h,p,t) : Silicon substrate capacitance
t h
h
))(d/
tdp(
εεπ
L
)b
a(
εεπ C
r
rsubSi
2
2ln
2
2
1
2ln
2
2
1
0
0_
d
h
p
a b
a b
t
Ref) Matthew N.O. Sadiku, Elements of Electromagnetics, 3th Edition
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Scalable Equivalent Circuit Model of a TSV
9
RSi (d,p,h) : Resistance of Silicon
hd)ump
(
ump.
ζS
L R subSi
502
10
3070
_
CBump (d,p,h) : Capacitance between Bumps
h
p
p/2+d+50um
um)D
π(p-D
εε C r
bump 102
0
p
D
10um L
Ref) Matthew N.O. Sadiku, Elements of Electromagnetics, 3th Edition
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Scalable Equivalent Circuit Model of a TSV
10
RTSV (d,h) : Resistance of TSV
))-δd
()d
((π
h)e.(
A
lρ R
skin depth
TSV
22
22
8721
LTSV (d,h,p,D) : Inductance of TSV
))D/
p(um)()
d/
p((h
π
)eπ(
)a
p(
π
lμ LTSV
2ln20
2ln
74
ln0
h
d
δSkin depth p
h
d
D 10 um
a
l
l
Ref) Matthew N.O. Sadiku, Elements of Electromagnetics, 3th Edition
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Signal TSV Ground TSV
SiO2
Si
Cu Cu
Signal current
Leakage current
Insertion Loss of a TSV in Low Frequency Range
11
Cinsulator
Cinsulator Cinsulator
Cinsulator Cinsulator
Cinsulator dominantly affects frequency
dependency of insertion loss of a TSV.
1 -6
-5
-4
-3
-2
-1
0
10 20 0.1 Tra
nsm
issio
n c
oeffic
ient
(S21)
[dB
]
Frequency [GHz]
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Signal current
Leakage current
Signal TSV Ground TSV
Insertion Loss of a TSV in Mid Frequency Range
12
CSi sub dominantly affects frequency
dependency of insertion loss of a TSV.
CSi sub
CSi sub
1 -6
-5
-4
-3
-2
-1
0
10 20 0.1 Tra
nsm
issio
n c
oeffic
ient
(S21)
[dB
]
Frequency [GHz]
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Signal current
Leakage current
Signal TSV Ground TSV
Insertion Loss of a TSV in High Frequency Range
13
CBump
CBump
CBump
CBump dominantly affects frequency
dependency of insertion loss of a TSV.
1 -6
-5
-4
-3
-2
-1
0
10 20 0.1 Tra
nsm
issio
n c
oeffic
ient
(S21)
[dB
]
Frequency [GHz]
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
14
Re-distribution Layer
(RDL)
Signal TSV Ground TSV
Top die
Bottom die
Bump
Re-distribution Layer
(RDL)
Designed TSV Channel for Experimental Verification
Designed TSV Channel with Single-ended Signal TSVs
Re-distribution layer (RDL)
Through Silicon Via
(TSV)
Re-distribution layer (RDL)
for connecting TSVs
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
15
Probe
Station
Vector
Network
Analyzer
(VNA)
Cascade
probe
High
speed
cable
Measurement Environment for Experimental Verification
Vector Network analyzer (VNA)
Agilent Technologies / N2530A
(300kHz-20GHz)
Cascade Probe
I40-GS/SG 100um pitch
High Speed Cables
Micro-coax
(Frequency range : 0.05-26.5GHz)
(Insertion loss : 1.57dB/m at 26.5GHz)
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
16
0.1 1 10 -3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
20
Frequency (GHz)
S21 m
agnitude (
dB
)
Measurement Proposed model
Cinsulator
CSi sub
CBump
TSV has capacitive characteristic which brings frequency dependency to
loss of a TSV.
Insulator capacitance, Cinsulator, dominantly affects the overall frequency
dependent loss of a TSV.
Verification of the Analyzed TSV loss by Measurement
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Bump Bump
The Proposed TSV Equalizer using an Ohmic Contact
We intentionally made leakage by using an Ohmic contact
resulting in DC attenuation between signal and ground TSV.
17
n-type
Silicon
Substrate
n+ high
doped Silicon
Ohmic contact (Al/n+ type)
Signal
TSV
Ground
TSV
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Signal TSV Ground TSV
Signal current
Intended Leakage current
Intended DC attenuation of the Proposed TSV Equalizer
18
Ohmic contact brings
DC attenuation!
After Equalization
Before Equalization
1 -6
-5
-4
-3
-2
-1
0
Tra
nsm
issio
n c
oeffic
ient
(S21)
[dB
]
Frequency [GHz]
10 20 0.1
Rcontact Rcontact
Rcontact Rcontact
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Metal Patterning
Process of the Proposed TSV Equalizer
19
Lithography
Silicon Substrate
Insulator Deposition
Silicon Doping
Via Etch
Back-grinding
Ohmic contact
Signal
TSV
Ground
TSV
Metal
Silicon
Substrate
Metal Plating
Chemical Mechanical
Polishing (CMP)
Back-side Metal Patterning
Backside Silicon doping
The Proposed TSV Equalizer
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Simulation Item for Verification of the TSV Equalizer Performance
20
TSV diameter 75 um
TSV height 90 um
TSV-to-TSV pitch 150 um
SiO2 thickness 0.1 um
TSV dimension
Ohmic Contact information
Junction depth 1 um
Resistivity of
Junction
0.032 Ω·cm
Resistivity of
Silicon
10 Ω·cm
Contact Width 22.5 um
Number of stacked dies 8
Ground Signal Ground
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
0.1 1 10 -8
-6
-4
-2
0
Tra
nsm
issio
n c
oeffic
ient
(S21)
[dB
]
Frequency [GHz]
20
Flattened from DC to 10GHz
(Nyquist frequency of 20Gbps)
- 4.5
0.7dB 1 dB
-3.8 dB
4.8 dB
Frequency Domain Simulation-based Verification of the TSV Equalizer Performance
21
Insertion loss of 8 TSVs
without TSV equalizer
Insertion loss of 8 TSVs with TSV equalizer
• We successfully flattened frequency dependent loss by 3.8 dB
by using TSV Equalizer.
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Time Domain Simulation-based Verification of the TSV Equalizer Performance
Time (ps) 0 100 80 20 40 60
-0.25
0.25
0
Voltage (
V)
• We successfully achieved normalized pk-pk jitter and eye-opening,
32% and 20%,
meanwhile the unequalized eye is completely closed.
22
Time (ps) 0 100 80 20 40 60
-0.25
0.25 Pk-pk jitter : 16 ps
Eye opening: 100mV
0
Voltage (
V)
Terahertz Interconnection and Package Laboratory TERA Terahertz Interconnection and Package Laboratory
Conclusion
23
We analyzed the loss mechanism of a TSV with scalable equivalent
circuit model which is verified with measurement.
We analyzed the frequency dependent loss of a TSV which is
capacitive and resistive.
We proposed the TSV Equalizer by using DC attenuation from an
ohmic contact to flatten the frequency dependent loss of a TSV.
With the proposed TSV Equalizer, we achieved normalized timing jitter
and eye opening, 32% and 20%, even with the almost closed eye.