Semiconductor Device Modeling and Characterization – EE5342 Lecture 7 – Spring 2011
Semiconductor Device Modeling and Characterization – EE5342 Lecture 34 – Spring 2011
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Transcript of Semiconductor Device Modeling and Characterization – EE5342 Lecture 34 – Spring 2011
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Semiconductor Device Modeling and
Characterization – EE5342 Lecture 34 – Spring 2011
Professor Ronald L. [email protected]
http://www.uta.edu/ronc/
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The npn Gummel-Poon Static ModelC
E
BB’
ILC
ILE IBF
IBRICC - IEC = IS(exp(vBE/NFVt
- exp(vBC/NRVt)/QB
RC
RE
RBB
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Gummel Poon npnModel Equations
IBF = ISexpf(vBE/NFVt)/BFILE = ISEexpf(vBE/NEVt)
IBR = ISexpf(vBC/NRVt)/BRILC = ISCexpf(vBC/NCVt)
QB = (1 + vBC/VAF + vBE/VAR ){½ + ¼ + (BFIBF/IKF + BRIBR/IKR)}
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Values for ms
with metal gate
02586.0V ,12.1E ,19E8.2N10E45.1n ,05.4 ,28.4
NNlnV :Si-n to Al
nNlnVq2
EnNNlnV :Note
nNNlnV :Si-p to Al
tgC
iSiAlm,
dCtSiAlm,ms
iat
g2i
aCt
2i
aCtSiAlm,ms
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Values for ms
with silicon gate
idt
g
dCt
dCtSi
gSims
iat
g2i
aCt
2i
aCtSiSims
nNlnVq2
ENNlnV :Note
NNlnVq
E :Si-n to poly p
nNlnVq2
EnNNlnV :Note
nNNlnV :Si-p to poly n
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8Fig 10.15*
ms(V)
NB (cm-3)
Typical ms values
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Flat band with oxidecharge (approx. scale)
Ev
AlSiO2
p-Si
EFm
Ec,Ox
Eg,ox~8eV EFp
Ec
Ev
EFi
'Ox
'ss
msOxmsFB
Ox
Oxc
Ox
'ss
x
ssm
ss
CQVV
xV
dxdE
q1QE
surface gate the onis Q'Q' charge
a cond FB at thenbound, Ox/Si the at
is Q' charge a If
q(fp-ox)q(Vox)
q(m-ox)
q(VFB) VFB= VG-VB, when Si bands
are flat
Ex
+<--Vox-->-
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Flat-band parametersfor n-channel (p-subst)
0nNlnVq2
EnNNlnV
gate, Si-poly n a For
den chg Ox/Si the is 'Q ,x'C
'C'QV :substratep
iat
g2i
actms
sms
ssOxOx
Ox
OxssmsFB
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Flat-band parametersfor p-channel (n-subst)
0nNlnVq2
EnNNlnV
qE gate, Si-poly p a For
den chg Ox/Si the is 'Q ,x'C
change) (no 'C'QV :substraten
idt
g2i
dvtms
gsms
ssOxOx
Ox
OxssmsFB
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Inversion for p-SiVgate>VTh>VFB
Vgate> VFB
Vsub = 0
EOx,x> 0
inversion for threshold above
E Induced depletes 0
E Induced
0xVE
Si
SiOxOx
x,Ox
Acceptors
Depl Reg
e- e- e- e- e-
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Approximation concept“Onset of Strong Inv”• OSI = Onset of Strong Inversion occurs
when ns = Na = ppo and VG = VTh
• Assume ns = 0 for VG < VTh
• Assume xdepl = xd,max for VG = VTh and it doesn’t increase for VG > VTh
• Cd,min = Si/xd,max for VG > VTh • Assume ns > 0 for VG > VTh
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MOS Bands at OSIp-substr = n-channel
Fig 10.9*
2q|p|
qp
xd,max
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Computing the D.R. W and Q at O.S.I.
Ex
Emax
x
aSi
x NqdxdE
a
pSid qN
x
22
,max
parea 2
,max,max' dad xqNQ
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Calculation of thethreshold cond, VT
Ox the across Q' induce to addedvoltage the isV where V,VVsub)-p sub,-(n xNqQ' is
charge extra the and x of value the reached has region depletion
The inverted. is surface the whenreached is condition threshold The
d,max
FBT
d,maxBd,max
d,max
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Equations forVT calculation
substr-n for 0 substr,- p for 0VqN22x ,xNqQ'
0nNV 0N
nV
CQ2VV substrnp
da
npd,maxd,maxa,dd,max
id
tnai
tp
Ox
dnpFBT
,
,
',max
,
,ln,ln
':,
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Fully biased n-MOScapacitor
0y
L
VG
Vsub=VB
EOx,x> 0
Acceptors
Depl Reg
e- e- e- e- e- e- n+ n+
VS VD
p-substrate
Channel if VG > VT
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MOS energy bands atSi surface for n-channel
Fig 8.10**
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Computing the D.R. W and Q at O.S.I.
Ex
Emax
x
aSi
x NqdxdE
a
SBpSid qN
VVx
)(22,max
)(2 SBp VVarea
,maxda,maxd xqNQ
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Q’d,max and xd,max forbiased MOS capacitor
Fig 8.11**
xd,max
(m) )2-
d,max
(cmq
Q'
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Fully biased n-channel VT calc
0V ,qN
VV22x
,xNqQ' ,0NnlnV
VV'C'Q2VVV
VV :substratep
aCBp
d,max
d,maxad,maxaitp
FBOx,maxd
pFBCT
Tthreshold at ,G
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n-channel VT forVC = VB = 0
Fig 10.20*
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References* Semiconductor Physics & Devices,
by Donald A. Neamen, Irwin, Chicago, 1997.
**Device Electronics for Integrated Circuits, 2nd ed., by Richard S. Muller and Theodore I. Kamins, John Wiley and Sons, New York, 1986