1
EEvaluation valuation TestTest RResultesultss of of AAntifuse ntifuse TType FPGAype FPGA
2005.10.28Noriko YAMADA
Electronic, Mechanical Components and MaterialsEngineering Group
2
BackgroundBackgroundIn the U.S., the failures of antifuse type FPGA (RTSX-S and SX-A) produced with MEC die (MEC device) have been reported from the beginning of 2003.An Industry Tiger Team (ITT) and NASA have made investigations and evaluation tests to find out the cause of the failures (ongoing).From the evaluation test results, the failure phenomenon is considered to be the increase in the delay time by the increase in resistance of an antifuse.The antifuse degradation is attributed to the problem of the structure of the MEC devices , and the manufacture recommends change to the UMC devices which are compatible with the MEC devices.In order to evaluate the risk of the MEC devices already mounted in the PWB and to determine the management plan for every project, the evaluation test was carried out by JAXA.
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APPENDIX(1): APPENDIX(1): AntifuseAntifuse (MEC)(MEC)
W-Plug
a:Si
Al
Ti
Ti
Before programming
unprogrammedunprogrammed AntifuseAntifuse
After programming
Programmed Programmed AntifuseAntifuse
“Reliability of Antifuse-Based Field Programmable Gate Arrays for Military and Aerospace Applications,” MAPLD 2001
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IntroductionIntroduction
Risk assessment of MEC die DevicesTo determine the acceleration factors and the failure rates about antifuse failures.Long-term life tests and thermal shock tests are carried out .
Reliability evaluation of UMC die DevicesThe UMC device has just received QML authorization in October, 2004, and UMC does not have experience used in the space. To evaluate the reliability for space applications by performing long-term life tests and radiation tests.
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Test SamplesTest Samples
Original(ver. 4.48)UMC die110Actel Corp.RTSX32SU-
CQ256E
Old(ver. 4.42)MEC die320Actel Corp.A54SX72A-
CQ256M
Old(ver. 4.42)MEC die190Actel Corp.A54SX32A-
CQ256M
ProgramAlgorithmRemarkSample
SizeManufacturerPartNumber
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Test Vehicle (1)Test Vehicle (1)
4-input AND-OR chains : Maximum utilization of antifusesStable operation using an external clock circuit:Easier failure detectionR-cells driven by skewed clock: Delays detectable to less than 10nsecContinuous monitoring of XORed outputs from the same circuit block: Real-time detection of failures
x4:32A32SU
x8:72A
Block UnitBlock Unit
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RTSX32SU
RT54SX32S
RT54SX32S
A54SX72A
A54SX32ARTSX32SU
Part No.
12102
13012
13015
3654536545
1790617906
Dynamic fuse Count (Total)
-
-
-
8
4
Circuit BlockCount
15102151022144321443
46967406NASA
51787834General Test
51977818Colonel Test
7931793199759975JAXAJAXA
High CurrentFuse Count
(F,X,G,V,H,W)
Low Current Fuse Count
(I,S,K,B)
Designtype
Test Vehicle (2)Test Vehicle (2)The number of antifuses in test vehicles
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5--Total Ionizing Dose (TID)5--Single Event Effect (SEL/SEU)
Radiation Test
907745-65 to +150deg.C,1000 cyclesThermal Shock Test-774525 deg.C, 33MHz, 1000H
1007745125 deg.C, 1MHz, 1000H-774570 deg.C, 1MHz, 1000H-774525 deg.C, 1MHz, 1000H
Long-term Life Test
RTRTSX32SUSX32SU
A54A54SX72ASX72A
A54A54SX32ASX32A
Sample SizeSample SizeConditionConditionTest ItemTest Item
Test Items and ConditionsTest Items and Conditions
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Test EnvironmentTest Environment
Handling EnvironmentHandling EnvironmentESD protected / designated areaESD protected / designated area
-- Vacuum wandsVacuum wands-- Globes requiredGlobes required-- Wrist strapWrist strap-- ESD shoesESD shoes
-- ESD safe table matsESD safe table mats-- Ionizer (ATE area)Ionizer (ATE area)-- Antistatic floor Antistatic floor etc. etc.
Test SystemsTest SystemsPrevention of EOSPrevention of EOS
-- Signals and power supplies within Signals and power supplies within recommended operating conditions recommended operating conditions described in datasheetdescribed in datasheet
(ex. Power strip with noise filter)(ex. Power strip with noise filter)
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Test Results (Test Results (11): ): Weibull PlotsWeibull Plots72A Weibull Plot
y(125C) = 0.0954Ln(x) - 2.6000y(70C) = 0.1002Ln(x) - 2.7259y(25C) = 0.1118Ln(x) - 2.8132
-5
-4
-3
-2
-1
1 10 100 1000 10000Time [Hour]
ln(-l
n(1-
F))
125C70C25C
Comparison of Weibull Plot
y(72A, 25C) = 0.1118Ln(x) - 2.8132
y(32A, 25C) = 0.0518Ln(x) - 3.2763
-5
-4
-3
-2
-1
1 10 100 1000 10000Time [Hour]
ln(-l
n(1-
F))
25C(72A)25C(32A)
Weibull ParametersWeibull Parameters
6.528E+110.1002
70℃
6.857E+118.473E+10η
0.09540.1118β
125℃25℃
2.942E+27η
0.0518β
32AWeibull parameter (beta< 1) Infant mortality as the result in the U.S.
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Comparison of Failure Rate
1E+1
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
1 10 100 1000 10000 100000Time [Hour]
Failu
re R
ate
[Fit(
32A
Equ
ival
ent)] 25C(72A)
25C(32A)
Failure Rate for 72A
1E+1
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
1 10 100 1000 10000 100000Time [Hour]
Failu
re R
ate
[Fit(
32A
Equ
ival
ent)] 25C
70C125C
Test Results (Test Results (22): Failure Rate): Failure Rate
The temperature dependence of the failure rates is very small.
Since the structure of 32A and 72A is the same, the difference in the failure rates between 32A and 72A is considered to be lot dependence.
90% Confidence Interval (Upper-Lower)
90% Confidence Interval (Upper-Lower)
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Acceleration Factor (Ea=0.002eV)
y = 0.9567e-0.0218x
1E-1
1E+0
2 2.5 3 3.51000/T [1000/K]
Slop
e of
λ(t)
Test Results Test Results (3)(3): : Activation EnergyActivation Energy
Ea=0.002eV
The activation energy (Ea) was calculated based on the Weibull plot of 72A sample.
Ea=0.002eV → PPBI (125 deg.C, 240 hours) is almost ineffective in screening for the antifuse delay failures.
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Test Results Test Results (4):(4): UMCUMC
Long-term Life Test (1MHz・125℃・ 1000H)
→ No Failure
The failure by antifuse delay which was detected by the MEC device did not take place.
The failure by ESD was not observed.*
* In the evaluation in the U.S, the failure by ESD had occurred and it became clear that the electrostatic tolerance of 32SU is extremely low.
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Antifuse Delay Time DistributionAntifuse Delay Time DistributionSX72A, 25 deg. C, 1000H
0
1
2
3
4
5
6
7
8
1.0 10.0 100.0 1000.0 10000.log10(Delta tPD) [ns]
Occ
uren
ce
experimentnormal
SX72A, 125 deg. C, 1000H
0
1
2
3
4
5
1 10 100 1000 10000log10(Delta tPD [ns])
Occ
uren
ce
experimentnormal
SX72A, 125 deg. C, 1000H
0
1
2
3
4
5
1 10 100 1000 10000log10(Delta tPD [ns])
Occ
uren
ce
experimentnormal
SX72A, 70 deg. C, 1000H
0
1
2
3
4
5
6
7
1 10 100 1000 10000log10(Delta TPD [ns])
Occ
uren
ce
measuredexperiment
SX72A, 70 deg. C, 1000H
0
1
2
3
4
5
6
7
1 10 100 1000 10000log10(Delta TPD [ns])
Occ
uren
ce
measuredexperiment
SX72A, 70 deg. C, 1000H
0
1
2
3
4
5
6
7
1 10 100 1000 10000log10(Delta TPD [ns])
Occ
uren
ce
measuredexperiment
SX72A, 70 deg. C, 1000H
0
1
2
3
4
5
6
7
1 10 100 1000 10000log10(Delta TPD [ns])
Occ
uren
ce
experimentnormal
SX72A, 70 deg. C, 1000H
0
1
2
3
4
5
6
7
1 10 100 1000 10000log10(Delta TPD [ns])
Occ
uren
ce
measuredexperiment
SX72A, 70 deg. C, 1000H
0
1
2
3
4
5
6
7
1 10 100 1000 10000log10(Delta TPD [ns])
Occ
uren
ce
experimentnormal
The delta is well fitted to the log-normal distribution.
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Voltage Voltage AAccelerationcceleration FactorFactor72A Weibull Plot (Accelerated)
y(2.5V) = 0.1118Ln(x) - 2.8132
y (3.0V,a.f.=50)= 0.1079Ln(x) - 2.7912 R2 = 0.9867
-5
-4
-3
-2
-1
1 10 100 1000 10000 100000Time [Hour]
ln(-l
n(1-
F))
2.5V3.0V(a.f.=50)
Long-term life test was carried out on 72A at 3.0V following 1000H life test at 2.5V (@1MHz・25℃).
2.5V => 3.0V An acceleration factor is about 50 times.
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Frequency Frequency DDependabilityependability ((11)): : 32A32A
Comparison of Fairure Rate for 32A
1E+0
1E+1
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
1 10 100 1000 10000 100000Time [Hour]
Failu
re R
ate
[Fit(
32A
Equ
ival
ent)] 1MHz
33MHz
33MHz ⇔ 1MHzA failure rate is mostly the same and the frequency dependenceis not observed.
The thermal migration model which a manufacturer advocates cannot explain the results.
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Frequency Frequency DDependabilityependability ((22):): 72A72A
In order to avoid the influence of noise when testing at 33MHz, power supply voltage was set up 0.1V lower than when testing at 1MHz. the failure rate at 33MHz is low.
The voltage accelerationfactor calculated from page14 was about 3(0.1V). This is almost the same as that of estimated from this graph. No frequency dependability
Comparison of Fairure Rate for 72A
1E+0
1E+1
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
1 10 100 1000 10000 100000Time [Hour]
Failu
re R
ate
[Fit(
32A
Equ
ival
ent)] 1MHz
33MHz
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0.50
0.60
0.70
0.80
0.90
1.00
1.10
0 20,000 40,000 60,000 80,000 100,000Mission Duration (hours)
Pro
babi
lity
of N
o Fa
ilure
3years1year 5years 10years
85300FIT
25500FIT14500FIT
6700FIT
Survival ProbabilitySurvival Probability :: 72A72A
The survival probability over the mission time was calculated using the Weibull parameters and activation energy at the operating temperature of 40 degrees C after PPBI
FIT of 72A is large compared with general LSI for the space.
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1.0E-10
1.0E-09
1.0E-08
1.0E-07
0.1 1 10 100Frequency [MHz]
Cro
ss S
ectio
n [c
m2 /b
it]
Dyanmic(CKB pattern)Dyanmic(All 1)
Radiation Test Results (1)Radiation Test Results (1):: SEESEE
FrequencyFrequencydependencedependence
SEU(Single Event Upset) / SEL(Single Event Latch-up)- Japan Atomic Energy Agency(JAEA)TIARA* AVF CYCLOTRON- Xe (LET=64[MeV/mg/cm2])
SEL was not observed
SEU was not observed in the static state .
SEU were observed in the dynamic state, andshowed frequency dependence ( right figure).
•TIARA* (Takasaki Ion Accelerators for Advanced Radiation Application)
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Radiation Test Results Radiation Test Results (2)(2):: TIDTID
S/N 58607
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
0 100 200 300 400 500 600 700 800 900 1000Total Dos e [G y (Si)]
Icc
[A]
Ic c aIc c i
Manufacturer’s result JAXA result
The increase in power supply current was observed.Sharp increase of Icca at 600Gy(Si) Recovered to the initial value and the equivalent level after
annealing (100 degrees C with 168H)
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Thermal Shock Test ResultsThermal Shock Test Results
Thermal Shock Test
Conditions: -65℃~150℃
Test period: 1000 cycles
Test samples: MEC: 32A・72A, UMC: 32SU
No Failure was observed
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Summary Summary (1)(1)MEC:
Delays caused by anti-fuse degradation were observed and considered to be similar phenomena observed in evaluation conducted by ITT and NASA. The failure rates of MEC are large, compared with general LSI for the space.The temperature acceleration of the failure rates was too small to screen out the defective antifuses throughout PPBI (125deg.C 240hours)The frequency dependence of the failure rates was not observed. It is new findings that the degradation mechanism is not explained by thermal migration which manufacturer advocates.The degradation of antifuse is accelerated by supply voltage: accelerated about 50 times for 2.5V to 3.0V of Vcc.The delta tPD showed a stable behavior after failure.The failure rates have varied from lot to lot.
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Summary Summary (2)(2)UMC:
The failure by antifuse delay which was detected in the MEC device did not take place.The failure by ESD was not observed.SEL was not observed.SEU was not observed in static state but also in dynamic state, and showed frequency dependence:Xe (LET=64[MeV/mg/cm2]).The increase in power supply current was observed during TID testing. The trend is similar to the manufacturer’s data.
Thermal Shock TestingNo failure was observed.
Based on the test results, JAXA has decided to replace the Based on the test results, JAXA has decided to replace the MEC with UMC.MEC with UMC.
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APPENDIX(2)APPENDIX(2)--1: Test Data1: Test Data
631 631 631 631 631
Units
76 69 63 52 40
Failures
-2.26 0.1000 100
0.1206 0.1095
0.0826 0.0635
cumulative failure rateF(t) lnln(1/(1-F(t)))Test point
(hours)
-2.16 338-2.06 1011
-2.46 29-2.73 2
72A 25℃ 1MHz72A 25℃ 1MHz
-2.67 0.0673 652 44 2
652 652 652 652 652
Units
76 67 62 55 46
Failures
-2.31 0.0950 36
0.1206 0.1026
0.0842 0.0704
cumulative failure rateF(t) lnln(1/(1-F(t)))Test point
(hours)
-2.23 110-2.06 303
-2.44 16-2.63 4
72A 70℃ 1MHz72A 70℃ 1MHz
25
-2.30 0.0963 655 63 15-2.17 0.1085 655 71 40
655 655 655
655 655
Units
82 80 75
50 49
Failures
-2.11 0.1146 110
0.1253 0.1222
0.0764 0.0749
cumulative failure rateF(t) lnln(1/(1-F(t)))Test point
(hours)
-2.04 303-2.02 1067
-2.54 4-2.56 2
-2.88 0.0564 182 10 804 -2.88 0.0564 182101002
-3.11 0.0454 182 8 96 182
182
Units
9
7
Failures
0.0509
0.0399
cumulative failure rateF(t) lnln(1/(1-F(t)))Test point
(hours)
-2.99 522
-3.25 1
72A 125℃ 1MHz72A 125℃ 1MHz
32A 25℃ 1MHz32A 25℃ 1MHz
APPENDIX(2)APPENDIX(2)--2: Test Data2: Test Data