see scaling effects lloyd massengill 10 may 2005
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SEE Scaling Effects
Lloyd Massengill10 May 2005
MURI 05 Kickoff 10 May 2005 2
Institute for Space and Defense Electronics Vanderbilt Engineering
Hierarchical Multi-Scale Analysis of Radiation Effects
Materials
Device Structure
Device Simulation Circuit Response
IC DesignEnergy
Deposition
Defect Models
MURI 05 Kickoff 10 May 2005 3
Institute for Space and Defense Electronics Vanderbilt Engineering
Scaling and SEUs
“Unconventional” SEE Mechanisms in Technology Nodes Below 100nm:
Charge Sharing • Distributed effects
Secondary (nuclear) Reactions• Probabilistic effects
Track Size as Large as the Critical Region• Spatial effects
Circuit Speed on the order of Collection Dynamics• Temporal effects
MURI 05 Kickoff 10 May 2005 4
Institute for Space and Defense Electronics Vanderbilt Engineering
Scaling and SEUs
“Unconventional” SEE Mechanisms in Technology Nodes Below 100nm:
Charge Sharing • Distributed effects
Secondary (nuclear) Reactions• Probabilistic effects
Track Size as Large as the Critical Region• Spatial effects
Circuit Speed on the order of Collection Dynamics• Temporal effects
MURI 05 Kickoff 10 May 2005 5
Institute for Space and Defense Electronics Vanderbilt Engineering
Charge Sharing *
Issue: At the 250nm CMOS technology node, we have observed two “unusual” effects
Heavy Ion – Very low LETth Laser (2) – N-Well Edge
NFETs
PFETs
Quantum 4M SRAM SEU DataSample 581 Versus Operating Conditions
1.0E-13
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
0 10 20 30 40 50 60 70 80 90 100 110 120 130
LETeff (MeV/mg/cm2)
Upse
t Xse
ctio
n (c
m2/
bit)
No latchup after 1E7 particles @ LETeff of 120 MeV/mg/cm2. (3.6V, 125 C)
Quantum 4M SRAM SEU DataSample 581 Versus Operating Conditions
1.0E-13
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
0 10 20 30 40 50 60 70 80 90 100 110 120 130
LETeff (MeV/mg/cm2)
Upse
t Xse
ctio
n (c
m2/
bit)
No latchup after 1E7 particles @ LETeff of 120 MeV/mg/cm2. (3.6V, 125 C)
* McMorrow et al, ”Single-Event Upset in Flip-Chip SRAM Induced by Through-Wafer, Two-Photon Absorption”, accepted to the 2005 NSREC
Warren et al., “The Contribution of Nuclear Reactions to Single Event Upset Cross-Section Measurements in a High-Density SEU Hardened SRAM Technology”, accepted to the 2005 NSREC
MURI 05 Kickoff 10 May 2005 6
Institute for Space and Defense Electronics Vanderbilt Engineering
Charge Sharing Background *
Distributed-storage hardened SRAM cell:
“Single Node” events cannot produce an upset
Charge collection required at nodes on both legs
Event sequence• Sufficient charge must be
collected on one leg to float the opposite leg
• The floating leg must then collected enough charge to lose its state
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
H L
* Warren et al., “The Contribution of Nuclear Reactions to Single Event Upset Cross-Section Measurements in a High-Density SEU Hardened SRAM Technology”, accepted to the 2005 NSREC
MURI 05 Kickoff 10 May 2005 7
Institute for Space and Defense Electronics Vanderbilt Engineering
Charge Sharing Simulations *
Mixed-mode simulations (3-D TCAD + compact model) useful for efficiency
We constructed calibrated base structure for SEE mapping
VAMPIRE simulations: 4G Opteron nodes550,000 elements, 1.5 wks per
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
TCAD
SPICE* Olson et al, “Simultaneous SE Charge Sharing and Parasitic Bipolar Conduction in
a Highly-Scaled SRAM Design,“ accepted to NSREC 2005
MURI 05 Kickoff 10 May 2005 8
Institute for Space and Defense Electronics Vanderbilt Engineering
Charge Sharing Preliminary Findings *
Functionally disjoint, but physically adjacent nodes share charge
In addition, parasitic conduction affects PFET of opposite rail
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
Pull-Up
Access
Hardening
Pull-Down
Hardening
P-wellWithN-FET
N-wellWithP-FET
= Gate Poly = Diffusion
SensitiveRegion
H L
M7
M8
M9
M10
M2
M0
M4
M5
* Olson et al, “Enhanced Single-Event Charge Collection in Submicron CMOS Due to a Diffusion-Triggered Parasitic LPNP” presented at HEART 05
MURI 05 Kickoff 10 May 2005 9
Institute for Space and Defense Electronics Vanderbilt Engineering
Scaling and SEUs
“Unconventional” SEE Mechanisms in Technology Nodes Below 100nm:
Charge Sharing • Distributed effects
Secondary (nuclear) Reactions• Probabilistic effects
Track Size as Large as the Critical Region• Spatial effects
Circuit Speed on the order of Collection Dynamics• Temporal effects
MURI 05 Kickoff 10 May 2005 10
Institute for Space and Defense Electronics Vanderbilt Engineering
Secondary (Nuclear) Effects
Issue: Unable to explain upsets at very low LET in TCAD Upset cross section too small to be intra-cell variation
1.0E-13
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
0 10 20 30 40 50 60 70 80 90 100 110 120 130
LETeff (MeV/mg/cm2)
Ups
et X
sect
ion
(cm
2/bi
t)
Dyn, 3.14V, 125C Static, 3.14V, 125C Dyn, 3.3V, 32C
No latchup after 1E7 particles @ LETeff of 120 MeV/mg/cm2. (3.6V, 125 C)
Brookhaven Labs, 3/27/02rdb
Ultra Low (follow-on at BNL)
Approximate Ion ( -Track Area intra
)cell Limit
TCAD Prediction
TCAD with average
LET ion does not
explain low LET upsets
MURI 05 Kickoff 10 May 2005 11
Institute for Space and Defense Electronics Vanderbilt Engineering
Secondary (Nuclear) Effects Hypotheses
Nuclear reaction events can increase the effective LET to +/- 8x the incident LET for this simulation
In scaled technologies, the low probability of occurrence offset by: - high number of sensitive volumes (4 Mbit SRAM)- elimination of lower-LET sensitivity via hardening
LET NuclearReaction Events
-Electrons LET NuclearReaction Events
-Electrons523 MeV Neon
= 1.79 / /LET MeV mg cm2
MURI 05 Kickoff 10 May 2005 12
Institute for Space and Defense Electronics Vanderbilt Engineering
Secondary (Nuclear) Effects Preliminary Analysis *
MRED used for preliminary investigation of potential event sources:
Conceptually simple relative energy deposition experiment 1x108 Monte-Carlo type simulations Reactions in the interconnect materials result in charge
deposition from secondary species in the sensitive volume
2m3m
Sensitive Volume5m
All Cubes
523 MeV 20Ne
Oxide
Si2m
3m
Sensitive Volume5m
All Cubes
523 MeV 20Ne
Oxide
Si
Oxide Only Oxide and Metallization
2m3m
Sensitive Volume
5m
All Cubes
523 MeV 20Ne
Oxide
Si
Si
TiN
Al
1m1m
1m
2m3m
Sensitive Volume
5m
All Cubes
523 MeV 20Ne
Oxide
Si
Si
TiN
Al
1m1m
1m
W
* Warren et al., “The Contribution of Nuclear Reactions to Single Event Upset Cross-Section Measurements in a High-Density SEU Hardened SRAM Technology” accepted to the 2005 NSREC
MURI 05 Kickoff 10 May 2005 13
Institute for Space and Defense Electronics Vanderbilt Engineering
Secondary (Nuclear) Effects Preliminary MRED Results
Nuclear Reactions can produce products greater than 8x in energy deposition than the primary LET
Effect is exacerbated with inter-connect materials (tungsten, aluminum, etc…)
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.00E+02 1.00E+03 1.00E+04 1.00E+05 1.00E+06 1.00E+07 1.00E+08
Energy (eV)
# of
Eve
nts
SiO2/Si
W/Ti/TiN/SiO2/Si
Primary LET
* ( 1 10Nuclear events only in x 8 simulations)
High EnergyEvents
MURI 05 Kickoff 10 May 2005 14
Institute for Space and Defense Electronics Vanderbilt Engineering
Secondary (Nuclear) Effects On-Going Work
Integration of multiple tools• Layout• TCAD modules• MRED (nuclear)
Accurate spatial relationship between sensitive regions and materials
Interconnect material affects the probability of extreme value events
Events must occur near the sensitive region to upset the cell
A step closer to developing a predictive tool
MURI 05 Kickoff 10 May 2005 15
Institute for Space and Defense Electronics Vanderbilt Engineering
Scaling and SEUs
“Unconventional” SEE Mechanisms in Technology Nodes Below 100nm:
Charge Sharing • Distributed effects
Secondary (nuclear) Reactions• Probabilistic effects
Track Size as Large as the Critical Region• Spatial effects
Circuit Speed on the order of Collection Dynamics• Temporal effects
MURI 05 Kickoff 10 May 2005 16
Institute for Space and Defense Electronics Vanderbilt Engineering
Track Size
Issue: Device dimensions becoming
smaller than• Commonly assumed radial
dimensions for SE charge generation tracks
• Minority carrier diffusion lengths (even in Drain/Source regions)
Device topology has implications for charge deposition
(1) M. L. Alles, et. al. , “Considerations for Single Event Effects in Non-Planar Multi-Gate SOI FETs”, submitted for presentation at the 2005 IEEE International SOI Conference.
(2) R. Chau et. al., “Advanced Depleted-Substrate Transistors: Single-Gate, Double-Gate, Tri-Gate”, 2002 International Conference on Solid State Devices and Materials (SSDM 2002), Nagoya, Japan.
(1)
(2)
MURI 05 Kickoff 10 May 2005 17
Institute for Space and Defense Electronics Vanderbilt Engineering
Track Size
Preliminary Simulations: Simulation of an ion hit using 3D TCAD
• (Alpha Particle, LET=2.4 MeV/mg-cm2) • Normal incidence• Three locations (Body, Drain, Source)
Response shows much longer time profile vs. direct collection;• Potential profile indicates bipolar action
Hit to Channel
M. L. Alles, et. al. , “Considerations for Single Event Effects in Non-Planar Multi-Gate SOI FETs”, submitted for presentation at the 2005 IEEE International SOI Conference. Simulated Tri-gate device based on: J Choi et. al., IEDM Technical Digest, 647 (2004).
MURI 05 Kickoff 10 May 2005 18
Institute for Space and Defense Electronics Vanderbilt Engineering
Track Size
Preliminary Findings: Hits to Drain (and Source) can
lead to notable charge collection• Implication for sensitive area• Drain and source contribution
found to depend on contact placement and size
Energy deposition process in such small devices unclear• Convention LET concept may
break down• We will study this with detailed
simulations (MRED)• Accurate TCAD modeling
(FLOODS)
M. L. Alles, et. al. , “Considerations for Single Event Effects in Non-Planar Multi-Gate SOI FETs”, submitted for presentation at the 2005 IEEE International SOI Conference.
MURI 05 Kickoff 10 May 2005 19
Institute for Space and Defense Electronics Vanderbilt Engineering
Scaling and SEUs
“Unconventional” SEE Mechanisms in Technology Nodes Below 100nm:
Charge Sharing • Distributed effects
Secondary (nuclear) Reactions• Probabilistic effects
Track Size as Large as the Critical Region• Spatial effects
Circuit Speed on the order of Collection Dynamics• Temporal effects
MURI 05 Kickoff 10 May 2005 20
Institute for Space and Defense Electronics Vanderbilt Engineering
Circuit Speed
Issue:
GHz circuitry have response dynamics on the same order as charge collection transient profiles
In these cases, SE transients are indistinguishable from legitimate signals
Some hardening techniques are ineffective Dynamic modeling required Detailed SE charge collection profiles are needed
MURI 05 Kickoff 10 May 2005 21
Institute for Space and Defense Electronics Vanderbilt Engineering
Conclusions
An understanding of SEE in emerging, scaled technologies (SiGe, ultra-small CMOS and 3-d SOI) constructed with novel materials systems (strained Si, alternative dielectrics, new metallizations) requires:
Improved physical models for ion interaction with materials other than Si
Detailed SE track structure models Improved understanding of nuclear reaction effects Improved device physics for mixed-mode modeling Improved understanding of parasitic charge collection
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