Download InGaP HBT modeling, scaling and parameter extraction using HICUM

III-V HBT modeling, scaling and
parameter extraction using
TRADICA and HICUM
Yves Zimmermann, Peter Zampardi,
Michael Schroeter
Outline
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•
•
•
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MESA HBTs in TRADICA
Parameter extraction
Experimental results
Future work
Summary
Geometry definition in TRADICA
- MESA HBT cross section -
Emitter resistance
• TLM method not suitable
• different methods for extraction of RE
– open collector method (DC)
– 1/gm method (DC)
– calculation from RF-measurements (S-parameter)
• different emitter sizes needed to get area specific resistance r’E
(including contact and mesa resistance)
RE
r’E
RACC (possible access resistance)
1/AE
RE=r’E/AE+RACC
[r’E]=[Ohm um2]
Collector and base-emitter saturation
current densities
• plot log(I) vs. VBE @ VBC=0V (Gummel plot)
• linear fit over linear region gives IS(saturation current) and m
(emission coefficient)
• extract IS and m for transistors with different emitter area
• average m, calculate JS as current density
• split JS into an area and a perimeter specific value
Base emitter recombination current
density
• Extract base emitter saturation current first
• Calculate IBE and subtract it from measured values
• linear fit over linear region gives IRES(saturation current) and mRE
(emission coefficient)
• extract IRES and mRE for transistors with different emitter area
• average mRE, calculate JRES as current density
BE recombination current
I BE  I SBE  exp(
1.00E-03
1.00E-04
1.00E-05
1.00E-06
IB
1.00E-07
1.00E-08
1.00E-09
1.00E-10
Recombination
current component
1.00E-11
1.00E-12
1.00E-13
0.8
0.9
1
1.1
VBE
1.2
1.3
1.4
VBE
V
)  I SRE  exp( BE )
mBE VT
mRE VT
Transit time extraction
• in HICUM split into two components, τ0 for low-current region, Δτ as
high-current correction
• low current component only depending on VBC, extraction from plot of
transit time versus 1/IC in linear region
low current transit time tau0 vs. VBC
low current transit time verification
measured
8.00E-12
extracted
calculated
7.00E-12
4.50E-12
measured
calculated
tau0
6.00E-12
tau
5.00E-12
5.00E-12
fit
4.00E-12
3.50E-12
4.00E-12
3.00E-12
3.00E-12
2.00E-12
-
100.00 200.00 300.00 400.00 500.00 600.00
1/IC
2.50E-12
-3.00E+ -2.50E+ -2.00E+ -1.50E+ -1.00E+ -5.00E- 0.00E+ 5.00E00
00
00
00
00
01
00
01
VBC
Gummel characteristics verification
(rectangular devices)
IC vs. VBE measured and simulated for different emitter
areas
simulated (SPECTRE)
measured
Series3
Series4
Series5
Series6
1.00E+00
1.00E-01
1.00E-02
1.00E-03
log(IC)
1.00E-04
1.00E-05
1.00E-06
1.00E-07
1.00E-08
1.00E-09
1.00E-10
1.00E-11
1.00E-12
0.8
0.9
1
1.1
1.2
1.3
VBE 1.4
1.5
Collector current scaling
(rectangular devices)
IS
geomtry scaling of transfer current IS
4.00E-25
3.50E-25
3.00E-25
2.50E-25
2.00E-25
1.50E-25
1.00E-25
5.00E-26
0.00E+00
Practically no offset,
perimeter component
very small
0.0
20.0
40.0
60.0
emitter area
80.0
100.0
120.0
Gummel characteristics verification
(rectangular devices)
IB vs. VBE measured and simulated for different
emitter areas
simulated (SPECTRE)
measured
1.00E-03
1.00E-04
log(IB)
1.00E-05
1.00E-06
1.00E-07
1.00E-08
1.00E-09
1.00E-10
1.00E-11
1.00E-12
0.8
0.9
1
1.1
1.2
1.3
VBE
1.4
1.5
Base emitter current scaling
(rectangular devices)
IS
geometry scaling of base emitter current IBE
8.00E-26
7.00E-26
6.00E-26
5.00E-26
4.00E-26
3.00E-26
2.00E-26
1.00E-26
0.00E+00
Offset indicates
perimeter component
-
20.0
40.0
60.0
emitter area
80.0
100.0
120.0
Output curves verification
(rectangular devices)
output curves (forced IB)
1.20E-02
1.00E-02
8.00E-03
IC
6.00E-03
4.00E-03
2.00E-03
simulated
(SPECTRE)
0.00E+00
measured
-2.00E-03
0
0.5
1
1.5
VCE
2
2.5
3
Base collector depletion cap.
(rectangular devices)
CBC vs. VBC measured and simulated for different
transistor sizes
simulated (SPECTRE)
9.00E-14
measured
8.00E-14
7.00E-14
CBC
6.00E-14
5.00E-14
4.00E-14
3.00E-14
2.00E-14
1.00E-14
0.00E+00
-10.0
-9.0
-8.0
-7.0
-6.0
-5.0
VBC
-4.0
-3.0
-2.0
-1.0
0.0
1.0
Low current transit time
low current transit time tau0 vs. VBC
extraction of low current transit time
5.00E-12
9.00E-12
measured
8.00E-12
linear fit
extracted
4.50E-12
fit
4.00E-12
6.00E-12
tau0
tau
7.00E-12
5.00E-12
3.50E-12
4.00E-12
3.00E-12
3.00E-12
2.00E-12
-
100
200
300
400
500
600
2.50E-12
-3
1/IC
-3
-2
-2
-1
VBC
-1
0
1
Importance of accurate measurements
transit time vs. 1/IC
6.00E-11
Gummelplot
5.00E-11
THIS IS BAD
4.00E-11
tau
1.00E+00
IC
1.00E-01
3.00E-11
2.00E-11
IB
1.00E-11
0.00E+00
1.00E-02
0
500
1000
1500
2500
3000
3500
4000
1/IC
1.00E-03
transit time vs. 1/IC
1.00E-04
9.00E-12
1.00E-05
8.00E-12
THIS IS BETTER
1.00E-06
7.00E-12
1.00E-07
tau
IC,IB
2000
6.00E-12
5.00E-12
1.00E-08
0.8
0.9
1
1.1
1.2
VBE
1.3
1.4
1.5
1.6
4.00E-12
3.00E-12
2.00E-12
-
100.00
200.00
300.00
1/IC
400.00
500.00
600.00
Summary
• General:
– HICUM model well suited for modeling DC characteristics
– Transit time model in HICUM has to be enhanced (velocity overshoot)
– Process variations over wafer seem to be very high
• Rectangular devices:
–
–
–
–
Parameters for geometry scaling have been extracted
Modeling of DC characteristics ok
Scaling equations in TRADICA well suited
Model parameter generation with TRADICA possible for low IC
applications
– Found relatively large bias independent (fringing) BC-capacitance,
probably base-metal isolation
• Ring emitter devices:
– CBC does not scale with whole BC area
– IC including large perimeter component (ledge working properly???)
Future work
• Enhancing HICUM transit time equations
• Implementing ring emitter scaling equations into TRADICA
• Verification of ring emitter calculations and parameter
generation
• Extraction and verification of high current transit time
parameters
• Library generation for HBT3 rectangular and ring emitter
devices
• Measuring transistors on different DIEs and wafers, and
DOEs for estimation of process variations
• Establishing statistical modeling capability using TRADICA