SPICE Compatible Models for Circuit Simulation of ESD Events
1. The World Leader in High Performance Signal Processing Solutions
EverywhereEverywhere
“SPICE Compatible
Models for Circuit
Simulation of ESD
Events”
Jean-Jacques (J-J) Hajjar,
Srivatsan Parthasarathy
& Paul Zhou
IEEE Electron Device Society Colloquium
University of Central Florida, Orlando, FL
March 20, 2012
2. EverywhereEverywhere
MOTIVATION
2
Key Drivers: the 3 “S”
Simulation: Predicting robustness of a particular
design to ESD prior to manufacture.
Synergy: Synthesize the physical concepts that
describes the ESD event into a self-contained
solution.
Simplicity: Automate and integrate simulation
flow in a standard circuit simulation
environment.
9. EverywhereEverywhere
Modeling Objectives & Approach
9
A. Verification
– Pass or Fail Robustness test
– Interaction with Core (or Protected) Circuitry
B. Optimization
– Redundant or insufficient protection?
C. Design Cycle Reduction
– First pass success
D. Simplicity
– Adopted by end-user
23. EverywhereEverywhere
Model Development
23
ESD Diode Model
Standard operation
Operation during
ESD event
-1 -0.5 0 0.5 1
Current (A)
Voltage (V)
`0.05
0.1
0.05
-4 -3 -2 -1 0 1
Voltage (V)
Current (A)
0.5
1.0
0.5
27. EverywhereEverywhere
Model Development
27
NPN Emitter-Base Breakdown Model
D1
R1
VEBO
● NPN BVEBO is modeled using:
– Ideal diode: D1
– Series resistance: R1
– DC source: VEBO=BVEBO
● Diode turns on at VEBO
Device Failure
(VM,IM)
NPN AE=0.35 5.2 m
BVEB0
SIMULATION
DATA
29. EverywhereEverywhere
Model Development
29
PNP Emitter-Base Breakdown Model
● A parallel breakdown is
observed at V>BVEBO
● This breakdown is modeled
using:
– Ideal diode: D2
– Series resistance: R2
– DC source: VEBO1=BVEBO1
r
PARALLEL
(R2)
BVEB0
PNP AE=4 1 10 m
PRIMARY
(R1)
Device Failure
(VM,IM)
SIMULATION
DATA
32. EverywhereEverywhere
Model Development
32
PNP Collector-Base Breakdown Model
● A Parallel breakdown path is
observed due to the reach-
through between extrinsic-
base/collector.
● Current flows laterally instead of
vertically.
D4
R4
D3
R3
VCBOVCBO1
33. EverywhereEverywhere
Model Development
33
Collector-Emitter Breakdown
● Impact ionization in the base collector depletion region.
● Electron-hole pairs swept into the base and collector respectively.
● Results in forward-biasing the base-emitter base junction.
● Current flow from emitter to collector sustains the avalanching in the
depletion region
N P N
E B C
35. EverywhereEverywhere
Model Development
35
Using MEXTRAM to Model
Collector-Emitter Breakdown:
● Weak avalanche is modelled in
MEXTRAM.
● The resulting current will turn-on
the Emitter-Base diode.
● This is sufficient to initiate and
sustain the breakdown.
● The collector resistance will be
optimized to model the conductivity
modulation.
● Velocity saturation is also modelled
in MEXTRAM.
S
RCV
C B E
CBCO CBEO
RCC
RBC
RBV
RE
IN
QBE IB
ISUB
QBCIBC
QSUB
E1
B1
B2
C1
C2
IAVL
36. EverywhereEverywhere
Model Development
36
Collector-Emitter Breakdown Model
NPN PNP
0
20
40
60
80
VOLTAGE (V)
0 4 8 12
Device Failure
(VM,IM)
BVCEO
NPN AE=1 10 m
CURRENT(mA)
SIMULATION
DATA
PNP AE=1 10 m
0 10 20
r
VOLTAGE (V)
CURRENT(mA)
BVCEO
0
20
40
60
80
Device Failure
(VM,IM)
37. EverywhereEverywhere
Model Development
37
Bipolar Model for ESD Event Simulations
D1
R1
Ci
Bi
Ei
MEXTRAM
D2
R2
CBO
Model
EBO
Model
VEBO
VCBO
C
E
B
D1
R1
Ci
Bi
Ei
D2
R2
D4
R4
D3
R3
VEBO
VCBOVCBO1
VEBO1
C
E
B
MEXTRAM
CBO
Model
EBO
Model
43. EverywhereEverywhere
Circuit Simulation Example
43
● The simulation identified NPN Q9 to go into BVCEO and conduct current
before the ESD protection turns on.
TLP CHARACTERISTICS OF INDIVIDUAL
NPN TRANSISTOR Q9
VOLTAGE TRANSIENT DURING
HBM STRESS
VOLTAGE(V)CURRENT(mA)
46. EverywhereEverywhere
Circuit Simulation Example
46
● Fix consists of adding resistor in series with transistor Q9
● Resulting current through transistor Q9 decreases to below failure level.
CURRENT TRANSIENT DURING HBM
STRESS ACROSS TRANSISTOR Q9
R R
Q1 Q2
Q3
R1
R3
Q4
VOUT
Q9
R
0
20
40
60
0 0.2 0.4 0.6 0.8 1
CURRENT(mA)
TIME (10-6
sec.)
FAILURE
ORIGINAL
DESIGN
REVISED
DESIGN
Q9: NPN AE=0.35 5.2 m
48. EverywhereEverywhere
SUMMARY
48
● An enhanced compact bipolar breakdown model was developed for a
SiGe bipolar process.
● The model was built around the industry-standard MEXTRAM compact
bipolar model, enabling SPICE-like circuit simulation.
● The model developed is integrated as part of the standard SPICE-type
circuit simulation environment.
● Simulation accuracy was confirmed using circuit simulation example and
the relevant Failure Analysis techniques.
● Predictive ESD simulation methodology used successfully on over four
dozen designs, over four bipolar process technologies and on various
design complexities.
49. The World Leader in High Performance Signal Processing Solutions
EverywhereEverywhere
“SPICE Compatible
Models for Circuit
Simulation of ESD
Events”
Jean-Jacques (J-J) Hajjar,
Srivatsan Parthasarathy
& Paul Zhou
IEEE Electron Device Society Colloquium
University of Central Florida, Orlando, FL
March 20, 2012