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www.nanohub.org

NCN

ECE606:SolidStateDevicesLecture39:ReliabilityofMOSFET

MuhammadAshrafulAlamalam@purdue.edu

1AlamECE-606S09

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Outline

AlamECE-606S09 2

1. Introducon2. NegaBveiasTemp.Instability3. GateDielectricreakdown4. RadiaBonInducedDamage5. Conclusion

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Warranty,productrecallandotherfactsoflife

AlamECE-606S09 3

Inthiscourse,you

arelearningto

analyze/design

MOSFETsthatgo

inanIC

becausetheICs

operateinincredibly

harshcondiBons,turningonandoff

trillionsofBme

duringitslifeBme.

thereforetheproperBesofthe

MOSFETkeepchanging.

Eventually,S/Dcanbeshorted,thegateoxidecanbreak,etc.

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SiOandSiHonds

AlamECE-606S09 4

Broken Si-H bonds

Negative Bias Temperature Instability (NBTI)

Hot carrier degradation (HCI)

Broken Si-O bonds

Gate dielectric Breakdown (TDDB)

Electrostatic Discharge (ESD)

Radiation induced Gate Rupture (RBD)

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NegaBveiasTemperatureInstabilityDefined

AlamECE-606S09 5

VD(volts)

ID(mA)

beforestress

aZerstress

012340

4

3

2

1

StressTime(sec)

%

degradaon

101103105107109

5

10

15

Spec.

Warranty

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NTIdefined

AlamECE-606S09 6

n~0.25Ea~0.5eVAdependsonEox

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DiffusionDistance

AlamECE-606S09 7

t1

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NITwithHdiffusion

AlamECE-606S09 8

NH

x

Combiningthesetwo,weget

SiSiSi H

HH

H

HH

H

Sisubstrate

Poly

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SiOonds

AlamECE-606S09 9

Broken Si-H bonds

Negative Bias Temperature Instability (NBTI)

Hot carrier degradation (HCI)

Broken Si-O bondsGate dielectric Breakdown (TDDB)

Electrostatic Discharge (ESD)

Radiation induced Gate Rupture (RBD)

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Outline

AlamECE-606S09 10

1. IntroducBon2. NegaBveiasTemp.Instability3. GateDielectricBreakdown4. RadiaBonInducedDamage5. Conclusion

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Time-dependentulkTrap

AlamECE-606S09 11

C/Cox

VG

IdealVT

ActualVT

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Dielectricreakdown

AlamECE-606S09 12

ln(Bme)GateCurrent reakdown

ln(-ln(1-F))

VG1>VG2>VG3 VDD64

20-2-4-6-8

-10

-20246810log(TBD)

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AnodeHoleInjecBonforDielectricreakdown

AlamECE-606S09 13

Anode

Cathode

e

h

NBD-DensityofpercolaBondefectsatbreakdown

Je-Electroncurrentdensity

a-ImpactIonizaBonRate(probabilitythataholewillbecreated

byanincomingelectron)

Tp-TransmissionRate(probabilitythattheholewilltravel

throughtheoxidelayer)

k-TrapGeneraBonEfficiency

(probabilitythattheholewillcreateapercolaBondefect)

OXIDE

JeaTpk

NBD

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AnodeHoleInjecBonTheoryofTDD

AlamECE-606S09 14

Jh=JeTpJe=Aexp(-B/E) =1-2Tp~const

ln(TBD)~1/R~1/E

Je~f(E)~Mexp(DV)ln(TBD)~1/R~V

AB

V~low

B

A

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PercolaBonModelforDielectricreakdown

AlamECE-606S0915

M

P1=NC1[p

1][(1-p)(N-1)]

P1=() exp(-)

with=(t/)and=M

F1()=1-Po()

Prob.ofexactly1BD

Prob.ofafilledcolumn:p=qM

Prob.offilledcell:q=(ata/NM)

ln[-ln(1-F1)]~lnt

ln(-ln(1-F))

100/million

VG1>VG2>VG3 VDD

64

20-2-4

-6-8-10

-20246810log(TBD)

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Outline

AlamECE-606S0916

1. IntroducBon2. NegaBveiasTemp.Instability3. GateDielectricreakdown4. RadiaonInducedDamage5. Conclusion

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RadiaBonInducedDamage

AlamECE-606S0917

Geant4highenergyparBclephysicsbasedtoolkit

UsedfortheionizaBonandenergyrelaxaBon(~10eVkeVs)

177MeVClion50Mrad(Si)8MeVelec

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RadiaBonInducedChargeuildup

AlamECE-606S0918

C/Cox

VG

IdealVT

ActualVT

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Summary

AlamECE-606S0919

1) ReliabilityisaseriousconcernforscalingofMOSFETs.2) TherearemanydifferenttypesofdegradaBon

mechanismsthatneedscarefulmodelingtopredictthe

lifeBmeofaMOSFETs.

3) Atpresent,NTIinPMOStransistorsisthemostdifficultreliabilityproblem,followedbyHCI,TDD,andRadiaBon

effects.