Radiation-Induced Pulse Noise in SOI CMOS Logic · 0.6-0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 Current (mA)...
Transcript of Radiation-Induced Pulse Noise in SOI CMOS Logic · 0.6-0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 Current (mA)...
Radiation-Induced Pulse Noisein SOI CMOS Logic
D. Kobayashi, K. Hirose, H. Ikeda, and H. SaitoInstitute of Space and Astronautical Science
Japan Aerospace Exploration Agency
ソフトエラー(などのLSIにおける放射線効果)に 関する第1回勉強会(京都)2011年9月7--8日Most part of this material is presented in an invited talk at
Int’l Symp on Advanced Semiconductor-on-insulator Technology and Related Physics 219th ECS Meeting, Montreal, Canada, May. 4, 2011
Outline
1. How serious radiation problems are
2. Merits and demerits of SOI
3. Pulse-noise problems in logic gate
4. Summary
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Radiation-Induced Pulse Noise in SOI CMOS Logic
An example of basic radiation effects
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Cu
rren
t (m
A)
Time (ns)
Smoothed Waveform
Signal Observed
ON current
Drain current behavior of 0.2-μm FD-SOI nMOSFET
Radiation strike (single Kr ion)
Makino (JAEA) et al., RASEDA 2010
Standing by in OFF state@VDS=1.8V
Basic parameters of studied SOI tech.
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Lg = 0.2 μm LDD DrainLOCOS
tox = 5 nm
tBOX = 100 nm
tSOI = 50 nm
8-inch bond-and-etch-back SOI wafer
Commercial 0.2-μm FD-SOI
Publication number history
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“soft error”SE & neutronSE & logic
Google scholar result (May 2, 2011): number of publications with keywords in anywhere in the articles and patents including citations
“Logic” and “Neutron”
It may not lessen Toyota's woes to hear that the problems the company has been having withfaulty gas pedals could be blamed on cosmic rays from space. Sound unbelievable? The concept isactually a lot more plausible than you might think.
Toyota Recall Might Be Caused by Cosmic RaysTechnology
By Denise Chow, LiveScience Staff Writerposted: 26 March 2010 11:32 am ET
Comments (21) | Recommend (13)
Soft error is a serous problem
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http://www.livescience.com/technology/toyota-recall-cosmic-rays-100326.htmlLiveScience (March 26, 2010)
ECC is already essential in cache memories for enterprise servers...
Intel developed rad-hard Itanium processor already...
Acceptable concept (Real reason is unknown)
Our living space is filled up with neutrons
Supernova
Sun
Earth
Galactic cosmic rays10GeV, 10/cm2·s
Space: H.-Siedle and Adams, “Hand book of radiation effects”, Oxford, 2001Terrestrial: Ziegler (IBM) et al., IBM J. Research and Development 40, 1996 p3
Nuclear reactions
n
π
n
n
Atmosphere
Solar flare1GeV, 1E5/cm2·s
Terrestrial neutrons 10/cm2·h @ sea level
secondary cosmic rays
n
How strong are they?
Linear Energy Transfer (LET), explains ionizing ability
Si
+−−++
−−++
−−++
−−+
+−
−
+
1 μm
LET 10 MeV·cm2/mg
100 fC
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SOI is known as a strong technology to radiation.Now is a time to show our stuff!
Outline
1. How serious radiation problems are
2. Merits and demerits of SOI
3. Pulse-noise problems in logic gate
4. Summary
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Radiation-Induced Pulse Noise in SOI CMOS Logic
People say, SOI is strong to radiation
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In the bulk case, noise charge in the deep substrate region can reach the signal (drain) terminal but not
in the SOI case because of the BOX layer.
Radiation
ElectronHole
Radiation
BOX
Bulk SOI
Large noise Small noise
That’s not so simple
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Parasitic bipolar structure can amplify noises
Small parasitic capacitance results in high sensitivity to noise signals
injection
escape
Electron
Holescreated byirradiation
Barrier lowering
Source
Drain
n
n
p
1.noise charge is deposited in body
2.holes are confined3.npn-BJT turns on
Large noise
How large?
Bipolar amplification effect
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Cu
rren
t (m
A)
Time (ns)
Smoothed Waveform
Signal Observed
~200 fC
x10 larger than charge deposited (20 fC)Important to suppress this amplification effect
Makino (JAEA) et al., RASEDA 2010
Body tie effect: SRAM sensitivity to n
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10-13
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SE
U c
ross
-sec
tio
n (
cm2 /b
it)
Gate length (μm)
Bulk
Our 0.2-μm FD-SOI
+BT
Baggio (CEA) et al., IEEE Trans. Nucl. Sci. 52, 2005, p2319
FD-SOI SRAM is harder than bulk but not enough.BT is effective to suppress parasitic bipolar amp. effect
~10 errors@year@1Gb@Ground
Rad-hard SRAM for space
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T. neutrons G. cosmic rays
3.6 9.0 40Threshold LET for bit upset in MeV•cm2/mg
Original
K. Hirose (ISAS) et al., IEEE Trans. Nucl. Sci. 49, 2002 p2965
Original FD SOI SRAM + Body tie + RC filter
RC filter is used for space applicationsCombined use of BT + RC is important
Only RC requires a really large RC value, practically unacceptable
Cell library is available
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Hirose (ISAS) et al.,日本航空宇宙学会誌 58(683), 2010 p365 (in Japanese)
All memory elements such as SRAM, latchesare protected by optimized RC + BT
Mitsubishi Heavy Industries, Ltd.SoC for space applications- 32-bit CPU (100MIPS) with FPU- Cache memory- SpaceWire Interface
Outline
1. How serious radiation problems are
2. Merits and demerits of SOI
3. Pulse-noise problems in logic gate
4. Summary
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Radiation-Induced Pulse Noise in SOI CMOS Logic
Pulse-noise problems in logic gate
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For now this SET effect is negligibleBut many predictions say it becomes serious soon
Radiation
Transient noise pulse = SET
1FF 0
capturepropagation
corruption
Logic gate network
Stored bit infomation
VOVDD
Time
CLK
Original pulse information is essential
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Radiation
Transient noise pulse = SET
1FF 0
capturepropagation
corruption
Logic gate network
Stored bit infomation
VOVDD
Time
CLK
i. On-chip pulse-width measurementii. Full-waveform observation techniqueiii. Physics-based analytical model
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Yanagawa (ISAS) et al., IEEE Trans. Nucl. Sci. 53(6) 2006 p3575
Radiation SET
111100011111
SNAPSHOT A(Time-to-digital converters)
12 NOR gates
input
digitize & record
read &decode
B
Target logic gates
On-chip pulse width measurement
World-first experimental demonstration
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0 0.2 0.4 0.6 0.8 1.0 1.2
10203040
0
SET width (ns)
Nu
mb
er o
f o
bse
rvat
ion
s Decodingaccuracy is not guar-anteed.
NORs (w/o BT) under irradiation with LET 40 MeV·cm2/mg
Yanagawa (ISAS) et al., IEEE Trans. Nucl. Sci. 53(6) 2006 p3575
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Comparison with bulkMakino (ISAS) et al., IEEE Trans. Nucl. Sci. 56(6), 2009 p3180
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Cro
ss s
ecti
on
(10
-9 c
m2 )
SET pulse width (ns)
90-nm bulk (by Narasimham et al.)
2/mg
1. Lower sensitivity than bulk 2. Shorter pulse (←?)
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Pulse can be broadened
Ferlet-Cavrois (CEA) et al., IEEE Trans. Nucl. Sci. 54, 2007, p2338
Propagation-induced pulse broadening (PIPB)
Floating body effect: dynamic VT change leads to pulse broadening during propagationWei (MIT) et al., IEEE Electron Device Lett. 17, 1996, p391
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Comparison with bulkMakino (ISAS) et al., IEEE Trans. Nucl. Sci. 56(6), 2009 p3180
0
2
4
6
8
0.0 0.5 1.0 1.5 2.0
Cro
ss s
ecti
on
(10
-9 c
m2 )
SET pulse width (ns)
90-nm bulk (by Narasimham et al.)
1000-gates chain (?)
Precise pulse-width comparison requires further study
24-gates chain (≤ 200ps PIPB)
Original pulse information is essential
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Radiation
Transient noise pulse = SET
1FF 0
capturepropagation
corruption
Logic gate network
Stored bit infomation
VOVDD
Time
CLK
i. On-chip pulse-width measurementii. Full-waveform observation techniqueiii. Physics-based analytical model
Full-waveform observation
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IDn
IDp
IDp
IDnVO
Radiation
VDD
VSS
Bias Tee
Oscilloscope
p-MT
n-MT
D
S
D
S
VSS
VDD
50 Ω
50 Ω
Target logic gate(inverter)
SET
VO
Time
Time
Time
Kobayashi (ISAS) et al., IEEE Trans. Nucl. Sci. 55, 2008 p2872
Waveform of SET experimentally observed in advanced CMOS tech.
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Original pulse information is essential
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Radiation
Transient noise pulse = SET
1FF 0
capturepropagation
corruption
Logic gate network
Stored bit infomation
VOVDD
Time
CLK
i. On-chip pulse-width measurementii. Full-waveform observation techniqueiii. Physics-based analytical model
Saturation tendency
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Dodd (Sandia National Lab) et al., IEEE Trans. Nucl. Sci. 51, 2004 p3278
Numerical device simulation results
Saturation
What makes this saturation tendency? Mechanics was unknown
Stating point of modeling
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VO
In
Plateau Ip(ON)
Rad
Device Sim. 130-nm SOI
V. Ferlet-Cavrois, IEEE Trans. Nucl. Sci. 53 (2006) 3242
Duration of plateau at Ip(ON) = Indicator of SET width
Numerical device simulation result
What mechanics is behind this plateau?
Band diagram analysis
30BJT operates in saturation during the plateau bottom
Forward biased
@ Initial
@ Plateaubottom
N P N
Kobayashi (ISAS) et al., IEEE Trans. Nucl. Sci. 56, 2009 p3043
Turn-off behavior of saturated BJT
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Sze and Ng, Physics of Semiconductor Devices 2007
Radiation effect = delta-function-like current injection
t1
T0Ip(ON)
t
t
QDEP
t
IB
IextForwardBiased(F.B.)
F.B.
IBt
QB
IC
t1
TSIext
t
t++ QB
IC
VCC
Rext
IB1
QB1
Demonstration
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t∗ = τ0 ln(
QDEP
Ip(ON)τ0
)+ τ1 +
CL|VTp|Ip(ON)
Bottom (storage time) Recovery
Kobayashi (ISAS) et al., IEEE Trans. Nucl. Sci. 56, 2009 p3043
0.2
0.4
0.6
0.8
100 101 102SE
T w
idth
@ |V
TP| (
ns)
Deposited charge: QDEP (fC)
Analyticalmodel Device
simulation
ln(QDEP)
0.2-μm FD-SOICMOS inverter
Good agreementSaturation = log behavior
1. How serious radiation problems areNeed to protect memory elements. Not only in space but also on the ground.
2. Merits and demerits of SOIBOX suppresses noise charge collection. Need a special care about increase in sensitivity due to small parasitic capacitance, bipolar amplification effect, and propagation-induced broadening
3. Pulse-noise problems in logicLogic gates need to be protected in near future. Characterization techniques such as pulse-width measurement, full-waveform observation technique, and physics-based analytical models are developed.
Summary
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Radiation-Induced Pulse Noise in SOI CMOS Logic