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HICUM workshop Bordeaux June 2011 1/14
SiGe spike mono emitter HBT modelling with Hicum
A. Bhattacharyya, C. Maneux, S. Frégonèse, T. Zimmer
IMS - University Bordeaux 1, France
HICUM workshop Bordeaux June 2011 2/14
Outline
Introduction: SiGe spike emitter
Basic principle
structure
Device simulation on SiGe spike transistor
Static characteristics
Dynamic characteristics
Compact modeling results
modeling with HICUML2V24
HICUM with an additional base current
Formulation of the model
Modeling results
Conclusion
HICUM workshop Bordeaux June 2011 3/14
Introduction: SiGe spike emitter
Basic principle:
From Choi IEEE EDL 2007
Inserting SiGe Spike
inside mono emitter
Increases hole recombination Increases base current
HICUM workshop Bordeaux June 2011 4/14
SiGe spike emitter is constructed with the help of IMEC device.
Introduction: SiGe spike emitter
SiGe spike mono-emitter mono-emitter
SiGe Spike
-0.10 -0.05 0.00 0.05 0.10
0.00
0.05
0.10
0.15
0.20
0.25
Ge
_c
on
ten
t(%
)
X(µm)
mono_emitter
SiGe_spike_emitter
x x
SIGe spike mono emitter device
X_mole fraction in both transistors
HICUM workshop Bordeaux June 2011 5/14
Device simulation on SiGe spike transistor
Device is simulated with calibrated parameter file and applying additional recombinatio for SiGe spike
-0.05 -0.04 -0.03 -0.02 -0.01 0.001E15
1E16
1E17
1E18
1E19
1E20
h_
de
ns
ity
(cm
-3)
X (µm)
mono_emitter
SiGe_spike
-0.08 -0.06 -0.04 -0.02 0.00 0.02 0.04 0.06 0.08 0.10
-2.0
-1.8
-1.6
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
Ba
nd
_e
ne
rgy
[e
V]
X [µm]
VBE= 0V
VBE= 0.9V
Energy band diagram comparing
SiGe spike emitter and mono emitter
h carrier density at VBE= 0.9V
h carrier density slope increses
near BE junction.
HICUM workshop Bordeaux June 2011 6/14
Device simulation on SiGe spike transistor
DC and AC Simulaton results with SiGe spike emitter are compared with the mono
emitter
0.4 0.5 0.6 0.7 0.8 0.9 1.0
1x10-11
1x10-10
1x10-9
1x10-8
1x10-7
1x10-6
1x10-5
1x10-4
1x10-3
1x10-2
Ic,
Ib [
A]
VBE
[V]
TCAD_monoEmitter
TCAD_SiGe_Spike
Base current increase
Gummel plot at VCB= 0V fT vs Ic plot at different VCE
10-4
10-3
10-2
0
50
100
150
200
250
300
fT [
GH
z]
Ic [amp]
SiGe_spike_Ft
monoEmitter_Ft
fT identical
HICUM workshop Bordeaux June 2011 7/14
Device simulation on SiGe spike transistor
7 20 55 148
-3.0
-2.8
-2.6
-2.4
-2.2
-2.0
-1.8
-1.6
-1.4
-1.2
-1.0
Ph
as
e(h
.m.2
1)
Frequency [GHz]
SiGe_Spike
MonoEmitter
VBE
7 20 55 1480.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
VBE
Ph
as
e(Y
.m.1
1)
Frequency [GHz]
SiGe_Spike
MonoEmitter
Excess recombination charge affects the phase of dynamic parameters at low
frequency
Phase of h21 at VCE= 0.5V and
VBE= 0.75V, 0.79V, 0.83V, 0.87V
Phase of Y11 at VCE= 0.5V and
VBE= 0.75V, 0.79V, 0.83V, 0.87V
HICUM workshop Bordeaux June 2011 8/14
Compact modeling on SiGe spike transistor
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
1E-20
1E-19
Ib/e
xp
(VB
E/V
T)
VBE
[V]
TCAD_SiGe_spike
HICUM_L2V24
SiGe spike mono emitter device simulation data are exported to ICCAP to perform
compact modeling with HICUML2
Gummel plot at VCB= 0V
vb [E+0]
ic.
s ic
.m i
b.m
ib.
s [L
OG
]
0.4 0.6 0.8 1.0 1.21E-12
1E-11
1E-10
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
1E-2
1E-1
Ib/exp(VBE/VT) at VCB= 0V
Base current is not perfect with the existing HICUM
HICUM workshop Bordeaux June 2011 9/14
Compact modeling on SiGe spike transistor
7 20 55 148-3.2
-3.0
-2.8
-2.6
-2.4
-2.2
-2.0
-1.8
-1.6
-1.4
-1.2
-1.0
VBE
Ph
as
e(h
.m.2
1)
Frequency [GHz]
TCAD
HICUM_L2V24
7 20 55 1480.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
VBE
Ph
ase
(Y.1
1)
Frequency [GHz]
TCAD
HICUML2V24
Modeling results of phase of h21 and Y11 also show some inconsistency at low frequency
Phase of h21 at VCE= 0.5V and
VBE= 0.75V, 0.79V, 0.83V, 0.87V
Phase of Y11 at VCE= 0.5V and
VBE= 0.75V, 0.79V, 0.83V, 0.87V
Additional recombination parameter necessary to model the phase
HICUM workshop Bordeaux June 2011 10/14
HICUM with an additional base current: formulation
Bf
Bhrec
bhrec
QI
1
Tf
Ef EffE
iQ
g
Ef
Berec
berec
QI
' ' ' 'exp 1 exp 1B E B EjBEi BEiS REiS Bhrec
BEi T REi T
V Vi i i I
m V m V
Recombination current due to Ge drop in BC junction
0f f Ef Bf CfQ Q Q Q Q
Where,
Base current components in HICUML2
Introducing an additional recombination current due to the excess hole charge
New model parameter
model parameter
HICUM workshop Bordeaux June 2011 11/14
Modeling results with the extended model,
HICUM with an additional base current: modeling results
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
1E-20
1E-19
Ib/e
xp
(VB
E/V
T)
VBE
[V]
TCAD
HICUM_L2V24
Extended_HICUM
Ib/exp(VBE/VT) at VCB= 0V
vb [E+0] SiG
e_
spik
e_
ic i
c.s
SiG
e_
spik
e_
ib i
b.s
[L
OG
]
0.4 0.6 0.8 1.0 1.21E-12
1E-11
1E-10
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
1E-2
1E-1
Gummel plot at VCB= 0V
Base current is perfect with the extended model
HICUM workshop Bordeaux June 2011 12/14
Modeling results with the extended model,
HICUM with an additional base current: modeling results
7 20 55 148-3.2
-3.0
-2.8
-2.6
-2.4
-2.2
-2.0
-1.8
-1.6
-1.4
-1.2
-1.0
VBE
Ph
as
e(h
.m.2
1)
Frequency(GHz)
TCAD_SiGe_spike
Extended_HICUM
HICUM_L2V24
7 20 55 1480.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
VBE
Ph
as
e(Y
.11
)
Frequency [GHz]
TCAD_SiGe_Spike
Extended_HICUM
HICUM_LV24
Phase of h21 at VCE= 0.5V and
VBE= 0.75V, 0.79V, 0.83V, 0.87V
Phase of Y11 at VCE= 0.5V and
VBE= 0.75V, 0.79V, 0.83V, 0.87V
Excess phase shift is modeled perfectly with the extended model
HICUM workshop Bordeaux June 2011 13/14
Conclusion
A SiGe spike mono emitter device is considered for physical devicesimulation (TCAD).
TCAD simulations show an increase in base current without affecting thetransit frequency.
Simulated results are modeled with HICUML2V24 model.
A small extension of HICUM with an additional recombination current isformulated.
Base current and Y11, h21 phase are accurately modeled with the new model.
HICUM workshop Bordeaux June 2011 14/14
Acknowledgment
This work is part of the:
• DOTFIVE project supported by the European Commission through the Seventh
Framework Programme for Research and Technological Development.
Acknowledgements also to the MEDEA+ “SIAM” project.
We want to thank Arturo.Sibaja-Hernandez from IMEC for fruitful discussions andprocess information supply.