Modeling and Reliability investigation with HiCuM for InP/InGaAs DHBT

S. Ghosh, F. Marc, C. Maneux, B. Grandchamp, G. A. Koné, T. Zimmer.

IMS Lab., University of Bordeaux 1.

11th HICUM Workshop 2011 (28th & 29th June)

IMS Lab., University of Bordeaux 1.

2/27

Purpose

Physics based modeling with high accuracy level (before aging)

Introduction of the InP HBT degradation laws into its compact model

An essential step to achieve built in reliability at circuit level

Implementation of aging circuit in compact electrical model

Impact of device failure mechanisms on the circuit in operating conditions.

3/27

Outline

The InP HBT: some technological aspects

Modeling with HiCuM L2 v2.24G

Summary of accelerated bias aging tests

Physical aging Model using TCAD tools

Electrical aging Model using HiCuM

Enhancement of the HiCuM model L2

Demonstration of the compact model including aging

Device level

Circuit level (Common emitter amplifier)

Conclusion

4/27

InP HBT: technological aspects

Name Material Level (cm-3)

G1

Thickness (nm)

G1

Cont Em In0.53Ga0.47As >1019 100

Emitter 2 InP >1019 180

Emitter 1 InP 2x1017 40

Base InX-1GaXAs 8 x1019 ≈30

Buffer In0.53Ga0.47As 1x1016 30

Collector 2 InP 5x1017 20

Collector 1 InP 2.5x1016 80

Cont Co 3 InP >1019 <100

Cont Co 2 In0.53Ga0.47As >1019 <50

Cont Co 1 InP >1019 350

Etch-Stop In0.53Ga0.47As 10

Contact Co 1

Contact Co 2

Contact Co 3

Collector 1

Emitter 2

Emitter Contact

Emitter 1

Buffer

Collector 2

Base

HBT devices from III-V Lab

InP substrate

GSMBE growth

Self-aligned triple-mesa process

Ti/Au metallization

Polyimide passivation.

5/27

Modeling with HICUM/L2 v2.24G

In advanced HBTs the effective reverse Early voltage decrease drastically with the increasing of RF performances

This small effective reverse Early voltages becomes strongly temperature dependant

The new version of HiCUM model is able to physically solve these problem and has already been demonstrated on SiGe HBT technology

InP DHBT technology faces similar types of problems

This new version* and the similar parameter extraction strategy* has been adopted for the modeling purpose

*Z. Huszka, D. Céli and E. Seebacher, “A Novel Low-Bias Charge Concept for HBT/BJT Models Including Heterobandgap and

Temperature Effects - Part I: Theory , Part II: Implementation, Parameter Extraction and Verification”, IEEE Trans. Electron. Dev., 2011

6/27

HICUM/L2 v2.24G new model equations

Collector current at low current densities

Temperature dependence

001 .

0 0.ETAG

T

G TZ

PP eQQ

01 .

.ETAGEZ

J

G

E E

T

T

J I IH eH

01 .

.ETAGCZ

J

G

C C

T

T

J I IH eH

TTT EEE

TTT CCC

0 0

0

0

1 .

. . ( ) . . ( )

BCBE

T T

VV

V V

C G G G

P JEI P E JCI P C

e e

IQ H Q T H Q T

C

7/27

Preliminary assumption of parameter values: ZEDC=0.999 and AJEDC=10

)(/1ln 0TVV DEDCBE

Extracted Parameters: IS, HJEI, VDEDC

Parameter Extraction Results (0.7x10 µm2) (1/2)

0.0E+00

2.0E+14

4.0E+14

6.0E+14

8.0E+14

1.0E+15

1.2E+15

1.4E+15

-2 -1.5 -1 -0.5 0

-HJEI/IS

1/IS

1A

BE

TV

V

Ce

I

8/27

Parameter Extraction Results (0.7x10 µm2) (2/2)

Extraction of QP0 Parameter

Optimization of parameters IS, HJEI, VDEDC, AJEDC and QP0

QP0 Extraction

IS, HJEI

VDEDC, AJEDC

and QP0

0,4 0,6 0,8 1,00,0

0,5

1,0

1,5

Temp = 27 OCI C

/eV

BE/(

Mcf*V

T) (

fA)

VBE

(V)

Meas

Sim

9/27

Normalized collector current

Impact of the temperature on the effective reverse early effect

Accuracy of temperature dependant parameters: ZETAG0, ZETAGE, ZETAGC, ZETACT, VGB, DELTE, DELTC

0.4 0.6 0.8 1.00

10

20

Temp = 50 OC

I C/e

Vb

e/(

MC

F*V

T) (f

A)

V BE

(V)

Meas

Sim

0.4 0.6 0.8 1.00

200

400

I C/e

Vb

e/(

MC

F*V

T) (f

A)

VBE

(V)

Meas

Sim

Temp = 80 OC

0.4 0.6 0.8 1.00.0

0.5

1.0

1.5

Temp = 27 OC

I C/e

Vb

e/(

MC

F*V

T) (

fA)

VBE

(V)

Meas

Sim

10/27

Fwd Gummel plots and Collector Current at different VCB

0.4 0.6 0.8 1.01E-9

1E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

I C (

A)

VBE

(V)

IC.M_27OC

IC.S_27OC

IC.M_50OC

IC.M_50OC

IC.M_80OC

IC.M_80OC

VBC

= 0

0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96

0.00

0.01

0.02

0.03

0.04

0.05

I C (

A)

VBE

(V)

Meas

Sim

VCE

= 0.8 to 1.2 V

@ 0.1V Steps

Temp= 27OC

11/27

Output and fT characteristics

-0.5 0.0 0.5 1.0 1.5 2.0

0

3

6

9

12

15

18

I C

(mA

)

VCE

(V)

Meas

Sim

IB sweep

100uA to 700uA

1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0,01 0,1 10

50

100

150

200

250

300

350

f T (

GH

z)

IC (A)

Meas

Sim

VBC

=0

0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,10

50

100

150

200

250

300

350

VBC

=0

f T (

GH

z)

VBE

(V)

Meas

Sim

12/27

Summary of Extraction results

Easier C10, QP0, HJEI extraction for HICUM/L2 (Convenient for single geometry parameter extraction procedure)

Unified approach between HL0 and HL2

Modeling of the reverse early effect

Temperature dependence of reverse early effect

Parameter extraction and validation on InP HBT technology at wide range of temperatures, from low to high current densities and in DC and AC conditions

13/27

Current density and bias stress conditions

Bias Point #1: (not used)

Vce : 1.5V

Jc: 400KA/cm²

Aging Temperature 30°C

Bias Point #2:

Vce : 2V

Jc : 400 KA/cm²

Aging Temperature 30°C

Tj = 100°C (T7)

Bias Point #3:

Vce : 2.5V

Jc : 400 KA/cm²

Aging Temperature 30°C

Bias Point #4:

Vce : 2.7V

Jc : 400 KA/cm²

Aging Temperature 30°C

Bias Point #2’:

Vce : 1.31V

Jc : 610 KA/cm²

Aging Temperature 30°C

Tj = 100°C (T7)

0.0 0.5 1.0 1.5 2.0 2.5 3.0

0

200

400

600

125°C118°C

100°C

83°C

P2'

P4P3P2

100µA <IB< 800µA step size 100µA

T7

JC (

KA

/cm

²)

VCE

(V)

P1

14/27

Results of accelerated bias aging tests

0.2 0.4 0.6 0.8 1.0

0

5

10

15

20

25 P3G1T7

Cu

rre

nt

Ga

in

Vbe [V]

Beta_0

Beta_1

Beta_2

Beta_4

Beta_8

Beta_16

Beta_24

Beta_72

Beta_250

Beta_500

Beta_750

Beta_1000

Beta_1250

Beta_1500

Beta_200040% At 0.95V

vc [E+0]

ic

.m

ic.m

@2

50

0h

[E

-3]

0.0 0.5 1.0 1.5 2.0 2.5 3.0-5

-0

5

10

15

20

25

0,2 0,4 0,6 0,8 1,010

-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

I (

A)

P3/G1/T7

VBE

(V)

0 to 72 hrs

250 to 2000 hrs

2500 hrs

IC

IB

15/27

Modeling through TCAD

TCAD simulations:

Introduction of donor traps on the entire surface of the emitter-base junction (trap level at ET-EV=0.83eV) IC, IB degradation (0.6V≤VBE≤1V).

0 1000 2000 30000,0

5,0x1011

1,0x1012

1,5x1012

E-B

junction d

onor

trap d

ensity @

Et-

Ev=

0,8

3eV

Time (hr)

Bias P4

Bias P3

Bias P2

Bias P2'

Linear fit

AE=0,7x7µm

2

Location Type Energy (ET-EV)

Emitter Sidewall Donor 1.3 eV

Extrinsic Base Acceptor 0.4 eV

Before aging the trap parameters and their locations

Recombination tunneling current at EB junction (0.2V≤VBE≤0.6V)

0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,910

-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

Meas @ 0h

TCAD (no EB traps)

Meas @ 1250h

TCAD (NT=1,15x10

-12cm

-2)

Curr

ents

(A

)

VBE

(V)

AE = 0,7x7µm

2

Jc = 400kA/cm

2

Tj = 125°C

16/27

Electrical modeling through HiCuM

The internal base current injected across the B-E junction is given by:

' '

exp 1 exp 1BEiS REiS

BEi REi

B E B EjBEi

T T

v vi

VI

m VI

m

The base current injected across the emitter periphery is given by:

* *exp 1 exp 1BEpS REpS

BEp RE

B E B EjBEp

T Tp

v vi

VI

m VI

m

Hicum L2

Parameter

Initial value 2500 hr aging

(P3)

Ibeis 0 34.0 E-15

Mbei 1.340 1.340

Ireis 598.9 E-15 598.9 E-15

Mrei 1.699 1.699

Ibeps 178.3 E-15 178.3 E-15

Mbep 1.517 1.517

Ireps 0 1.2 e-9

Mrep 4 4

IS 2.338 E-15 3.195 E-15

RE 4.01 4.86

17/27

HiCUM Parameter evolutions due to stress

0 500 1000 1500 2000 25000

5

10

15

20

25

30

35 P4

P3

P2

P2'

Linear fit

Ibe

is (

fA)

Stress time (hr)

0 500 1000 1500 2000 25002,2

2,4

2,6

2,8

3,0

3,2

3,4 P4

P3

P2

P2'

Linear fit

IS (

fA)

Stress time (hr)

0 250 500 750 1000 1250 15000,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

Ire

ps (

nA

)

time (hr)

P2

P2'

P3

P4

Exponential fit

of Ireps

1

1,05

1,1

1,15

1,2

1,25

0 500 1000 1500 2000 2500 3000re

/re

0

stress time (hr)

P4

P3

P2

P2p

Linéaire (P4)

Linéaire (P3)

Linéaire (P2)

Linéaire (P2p)

18/27

Electrical aging model

tTk

EJt

B

xax

CJT

,,

x,x expBAI

2,50 2,55 2,60 2,65 2,7010

-3

10-2

10-1

Ea, Ibeis

= 0.776 eV

constant increase

rate of Ibeis

of IS

fitted line

1000/T (1/K)A

T,J(I

be

is)

Ea, IS

= 1.32 eV

10-6

10-5

10-4

10-3

AT

,J (IS)

0 500 1000 1500 2000 2500 3000

0

10

20

30

40

50

60

Ibe

is (

fA)

Stress time (hr)

P4

P3

P2

P2p

P4

P3

P2

P2'

a, Ibeis = 0.776 eV

Where IX denotes IBEiS and IS parameters

Both junction temperature and current density dependence

Arrhenius Plot (T dependency)

Fitted lines following above equation

19/27

Implementation into HiCuM

Three new nodes that give IX(t, T,JC) and RE(t, T,JC)

JTX

dt

dI,A

Tk

EJ

B

xax

CJT

,,

x, expBA

module hic2_full (c,b,e,s,tnode,ibeis_out,is_out,re_out);

branch (ibeis_out) br_ibeisout;

branch (is_out) br_isout;

branch (re_out) br_reout;

// Aging model parameter initialization

parameter real ibeis0 = 0; is0 = 2.338e-15; re0 = 4.01; bibeis = 10.28e-15;

eibeis = 775.5m; alpha1 = 1.4; bis = 130.6p; eis = 1.206; alpha2 = 1.417;

aeff = 3.28E-8; (info="Effective emitter area unit cm2") ; atsf = 1.0; flage = 1

(info="Flag for turning on and off aging effect") ; bre = 2.778m;

ere = 543m; alpha3 = 771.4m;

// Declaration of variable

real aibeis,ais,are,ibeis,is,re;

//Model initialization

ibeis = V(br_ibeisout)+ibeis0; is = V(br_isout)+is0;

re = V(br_reout)*re0;

//Model evaluation

aibeis = bibeis*exp(-ibeis/((`P_K/`P_Q)*Tdev))*pow(((itf/1000.0)/aeff),alpha1);

ais = bis*exp(-eis/((`P_K/`P_Q)*Tdev))*pow(((itf/1000.0)/aeff),alpha2);

are = bre*exp(-ere/((`P_K/`P_Q)*Tdev))*pow(((itf/1000.0)/aeff),alpha3);

// Load Source

if (flage !=0) begin : Bias_aging

if (analysis("tran")) begin

if (analysis("ic")) begin

V(br_ibeisout) <+ 0.0;

V(br_isout) <+ 0.0;

V(br_reout) <+ 1.0;

end else begin

I(br_ibeisout) <+ -atsf*aibeis;

I(br_ibeisout) <+ ddt(V(br_ibeisout));

I(br_isout) <+ -atsf*ais;

I(br_isout) <+ ddt(V(br_isout));

I(br_reout) <+ -atsf*are;

I(br_reout) <+ ddt(V(br_reout));

end

end else begin

V(br_ibeisout) <+ 0.0;

V(br_isout) <+ 0.0;

V(br_reout) <+ 1.0;

end

end else begin

V(br_ibeisout) <+ 0.0;

V(br_isout) <+ 0.0;

V(br_reout) <+ 1.0;

end

20/27

Simulation results: Real aging conditions

Current Voltage regulation loop to maintain P3 bias condition (JC=400 kA/cm2 or IC= 13.33 mA and

VCE = 2.5V

+

-

VCE2.5V

Iset13.33mA

+

-

+

-

VcVs

IcIs

C

1uF

Q1NPN

R11

Experimental set up Simulation set up in ICCAP Software

21/27

Simulation results: Real aging conditions

P3 bias condition (JC=400 kA/cm2 or IC= 13.33 mA and VCE = 2.5V

time [E+6]

ib

[E

-3]

0 2 4 6 80.5

0.6

0.7

0.8

0.9

1.0

1.1

time [E+6]

vb [E

-3]

0 2 4 6 8838

840

842

844

846

848

850

22/27

Simulation results: circuit level

Common emitter amplifier

DC operating point (near peak fT condition):

Vbb=2V(DC)

AC amp=1V

Frequency=1GHz

Rb=1.0KΩ

Rc=120Ω

Vcc=2V

Thermal node

Ibeis-out

b

c

e

s

IS_out

Re_out

23/27

Transient Simulation results: circuit level

150 years (Aging time) 150 years (Aging time)

150 years (Aging time) 150 years (Aging time)

simulation time [s] [E-9]

IC

[A]

[E-3

]

0 200 400 600 800 10002

4

6

8

10

12

14

simulation time [s] [E-9]

VC

[V]

[E+0

]

0 200 400 600 800 10000.0

0.5

1.0

1.5

2.0

simulation time [s] [E-9]

tem

p [d

egre

e C

] [E

+0]

0 200 400 600 800 10008

9

10

11

12

13

simulation time [s] [E-9]

ibei

sout

[A

] [

E-1

5]

0 200 400 600 800 10000

2

4

6

8

10

12

24/27

Time scales

Three different time scales:

Electrical operating conditions (e.g.: frequency f=1GHz or higher, period t=1ns or less)

Thermal effect (CTH*RTH thermal time constant: 8 ns to 10ns)

Aging effect has to be simulated with respect to life time of the system (several years)

• Introduction of ATSF: Aging Time Scale Factor

• Gives a parallel time scale: actual time scale * ATSF (5x1015)

• CTH=3 pJ/K, Thermal time constant = 8 ns

25/27

Discussion

Implementation of “aging” into HiCuM

Adapt time scales: ATSF and CTH

Convergence

No particular problems detected so far

Allowed parameter ranges have to be checked

26/27

Conclusion

Investigation of reliability on InP HBTs

Measurements and compact modeling at t=0

Aging of devices at different current and bias stress conditions (up to 2500h) + intermediate characterization + parameter extraction

Physical modeling of aging and extraction of aging law

Electrical modeling of aging

Link between physical and electrical modeling results

Development of new compact model including aging

Application to circuit design (future work 100G modulator driver circuit)

27/27

This work is a part of the ROBUST project supported by the French Government through the ANR

Program “VERSO: Réseaux du futur et services”.

Thanks to III-V Lab (Alcatel -Lucent) for fruitful discussions and wafer supply.

Robust Website: http://extranet.ims-bordeaux.fr/ROBUST/

Acknowledgement

28/27

Additional slides (1/3)

0.4 0.6 0.8 1.010

-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

Cu

rre

nt

(A)

VBE (V)

Measurement

TCAD

0.2 0.3 0.4 0.5-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5 V

BE = 1,1V

VBE

= 1,0V

VBE

= 0,9V

VBE

= 0,8V

VBE

= 0,7V

VBE

= 0,6V

VBE

= 0,5V

BufferEmitter Collector

BV

energ

y level (e

V)

distance (µm)

BC

Base

blocking

spike

29/27

Additional slides (2/3): Physics of InP HBT: Transport across E-B junction

Thermionic Emission VS Thermionic Field Emission

Conventional transport cease to be valid at heterojunction interface

Currents and energy flux are then define by interface conditions

Thermionic Emission: Allow to take into account thermionic transport above the E-B junction discontinuity

Thermionic Field Emission: allow to take into account the field dependent tunneling and thermionic electron transport respectively through (through tunnel effect) and above the E-B junction discontinuity

ΔEC = 0.25eV TFE occurs

Determination of the tunnel mass

0,20 0,25 0,30 0,35 0,40 0,45 0,500,0

0,2

0,4

0,6

0,8

1,0

1,2

En

erg

y L

ev

el

(eV

)

Distance (µm)

Thermionic

Emission (TE)

Thermionic Field

Emission (TFE)

0,20 0,25 0,30 0,35 0,40 0,45 0,500,0

0,2

0,4

0,6

0,8

1,0

1,2

En

erg

y L

ev

el

(eV

)

Distance (µm)

Thermionic

Emission (TE)

Thermionic Field

Emission (TFE)

0,5 0,6 0,7 0,8 0,9 1,010

-6

10-5

10-4

10-3

10-2

10-1

100

Co

lle

cto

r c

urr

en

t (A

)

VBE

(V)

Measurement

mt=0,5 (TCAD)

mt=0,2 (TCAD)

mt=0,1 (TCAD)

mt=0,05 (TCAD)

mt=0,02 (TCAD)

mt=0,01 (TCAD)

T10B3H7

30/27

Additional slides (3/3)

ic [LOG]

ft.m

ft.s

[E

+9

]

1E-4 1E-3 1E-2 1E-10

100

200

300

400

-VBC [E+0]

C

jc.m

C

jc.s

[E

-15

]

-3 -2 -1 0 10

50

100

150