Murty, Johnson, Harame

Murty, Johnson, Harame BCTM 2001

RF BiCMOS Device Modeling

Extraction of HiCUM Model Parameters for SiGe Bipolar Transistors

M. Ramana Murty, J.Johnson and D. Harame9/27/01



Outline

• Extraction of Resistances• Base Resistances: CBEB Test Structure• Emitter Resistance: Open-Collector Method• Collector resistance: Test-Structure

• Extraction of Junction Capacitances• Cold S-Parameters (CBEBC Transistors)+ Test-Structures

• Extraction of Avalanche Parameters• Ib vs Vbc Characteristics (CBEBC Transistors)

• Extraction of Current Parameters• Gummel and Transfer Current Characteristics (CBEBC Transistors)

• Extraction of Transit Time parameters• Active S-Parameters (CBEBC Transistors)



Base-link Resistance be0/∆l

R (O )

Extrinsic Base Resistance

Test-Structure to Measure Base Resistances

• CBEB Configuration• l = 4.5 and 10 um• b = 0 to 0.8 (5-sizes)

B1

B2

C

E



Base Pinch Resistance and Zero Bias Hole Charge

rsBi (O/Sq )

Vbe(V)

chargesjunction internal theare Q and Q

and 0

here

, 0

11

jcijEi

∫=+==

=−

bejjcijEi dVCQQQjrsBirsBir

pQjQ

r

(1/r-1)

Qj

Vce= 0 and 0.5 V



Emitter Resistance: Open Collector method

Set Ic=0, Vary Vbe, Measure Vce, Ib. Plot Vce vs Ie and fit to:

baseinternal under the collector in mobilities

,1

2

1ln

=

+=

++=

µµµµ

µ

pc

nc

T

os

EEECE

Vf

IIfIrV VCE (V)

IE (A)

1/AE0

rE(Ω) Slope=ρKE

Offset ?



Junction Capacitances – Cold S-parameter Method

Cold => Vbe= -0.5 to +0.5 V, Vbc=0 and Vbe=0, Vce= -0.5 to +3.5 V

+=

+

−=

−=

+=

22121

22121.2

12

)12(2

)12()11(

YYrealRsub

YYimagf

Ccs

fYimagCbc

fYimagYimagCbe

π

π

πB

E

C

Sub

Cbc

Cbe

Ccs

Rsub

Eq.ckt under Cold operation



Cold S-par Cbcmeas.

Cbc=Cbcmeas-Ccox

Polyfit Cbc vs. size

Intercept= area partOf (Cbci+Cextbase)

Slope =peri part of Cjcb

Subtract Cex

Fit to C-V equ,=>c’jcb,m,vbi

Fit to C-V equ,=>cjci,m,vbi

Cextbase fromCapmons(CAC2XB)Cjcb,m,vbi

Ccox (=oxideoverSTI) :Capmons(CAC2XBMS)

Extraction Flow of the Components of Cbc



• CBEBC Structures: b=0.16, 0.32, 0.48, 0.64, 0.96 and l=8.4 um• Corrected for (a) Emitter Spacer, (b) extrinsic base and (c) oxide capacitance.• Fit to classical C-V relationship

CperiVs VoltageCarea Vs Voltage

Separation of Cbc into its Components



Base-Collector Weak Avalanche Model

2/ and 2 , )()0( where

)(exp)(

''''

''''

EnAVLn

nAVLCBbCBbAVL

CBDCijCi

AVLCBDCiAVLTAVL

AbqbafVIVII

VVCqVVfII

ε==−==

−−−=

I b(nA

)

I avl(n

A)

Vbc (V) -Vbc (V)

• Ib and Ic measured at a low Vbe where self-heating effects are negligible

5 device sizes



Separation of Ibe into Area and Perimeter Components

• Ibe has no perimeter component as implied by the Ibe/A Vs P/A plot

I beA (A

)



Separation of Ic into Area and Perimeter Components



Is=9.12e-19Qp0= 3.18e-14mcF=1.035

T

BE

BEjEip

psc V

VVQQ

QII +

++=

)(log)log()log(

0

0

Bias Dependent Early Effect

Ic(a

rea)

(Am

p)

Vbe (V)



Transit Time- Low Ic Region

( ) cppfciifEEfEf

CBjci

jciBfvlhf

bcB

ECxfT

IIbIcbbQVC

Cc

cc

gmCCrrr

f

..)(.)(

)( ,11)1(

.2

1

0000000

''

0000

0

τττ

ττττ

βτ

π

+==

=

−+−∆+=

Σ+

+++=

Qf0(area)= 5.7x10-17 Cτf0i/τf0p= 1.857

1/2π

f T (p

s)

16

10

21x103 4x103 7x103

1/Ic(low) (A-1)



1 ; 11

; .

.21.2

22

c

ck

hc

hc

hcc

ckhCs i

Iiaaii

waii

Iwfh −=++++

=

++=∆ ττ

Transit Time- High Ic Region and Critical Current Parameters

0.48x8.4 µm

Ick referred ∆τf



PTceff

ceff

ceffck VVvxxx

Vvrci

vI ).( ;

2101

lim1

10

lim

32

2−=

+++

+

=−

Ick vs VC’E’ for w = 0.16, 0.32, 0.48, 0.64, 0.96 um

Transit Time-Determination of the Ick Parameters



Conclusions

• Several of the HiCUM Model Parameters are Extracted and their Physical Meaningfulness Verified.

• Extraction of High-current parameters, Non-quasi-static effect parameters etc. is underway

3.



A Screen-shot of the Structure Data Required in Tradica

SEM+SIMS



A Screen-shot of the Model Parameter Data(1) Required in Tradica



A Screen-shot of the Model Parameter Data(2) Required in Tradica





Documents

Murty, Johnson, Harame