Radiation Effects in SiGe Devices
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Transcript of Radiation Effects in SiGe Devices
1John D. Cressler, 6/13/06
Radiation Effects in SiGe Devices
Bongim Jun, Gnana Prakash, Akil Sutton, Marco Bellini, Ram Krithivasan, and John D. Cressler
MURI Review: Vanderbilt University, Nashville, TNJune 13, 2006
School of Electrical and Computer Engineering777 Atlantic Drive, N.W., Georgia Institute of Technology
Atlanta, GA 30332-0250 USA
[email protected] (404) 894-5161 / http://users.ece.gatech.edu/~cressler/
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• Rapid Generational Evolution (full SiGe BiCMOS)
• Making Significant In-roads in High-speed Communications ICs• Many DoD-Relevant Opportunities
1st
2nd
3rd
4th
The SiGe Success Story
- very high performance SiGe HBT + best-of-breed Si CMOS- RF to mm-wave + analog + digital + passives for integrated SoC / SiP
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Half-TeraHertz SiGe HBT!
• 510 GHz peak fT at 4.5K!• World’s First Half-TeraHertz Si-based Transistor• Lot’s of Steam Left for SiGe HBT Scaling …
To appear in IEEE Electron Device Letters, July 2006
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Applications
Defense
Navigation
Automotive
Communications
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SiGe mm-wave SoC
Wireless 60 GHz (ISM band) Data Links (1.0 Gb/sec!)
Courtesy of Ullrich Pfeiffer of IBM
DARPA Funded
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SiGe Radar Systems
Begs For SiGe!
Potential Paradigm Shifting Impact for Phased Array Radar!
Single Chip X-bandSiGe T/R (4x4 mm2)
MDA Funded
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Extreme Environments
• Cryogenic Temperatures (e.g., 77K = -196C)• High Temperatures (e.g., 200C)• Radiation (e.g., Earth orbit)
CEV
Drilling
Cars
Aerospace
Moon / Mars
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Total-Dose Response
• Multi-Mrad Total Dose Hardness (with no intentional hardening!)• Radiation Hardness Due to Epitaxial Base Structure (not Ge)
- thin emitter-base spacer + heavily doped extrinsic base + very thin base
63 MeV protons @ 5x1013 p/cm2 = 6.7 Mrad TID!
200 GHz SiGe HBT
3rd
2nd
1st
4th
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• Observed SEU Sensitivity in SiGe HBT Shift Registers- low LET threshold + high saturated cross-section (bad news!)
P. Marshall et al., IEEE TNS, 47, p. 2669, 2000
1.6 Gb/sec
50 GHz SiGe HBTs
Goal…
Single Event Effects
The ‘Achilles Heel’ of SiGe and Space!
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• Collector-substrate (n+/p-) Junction Is a Problem (SOI solves this)
• Lightly Doped Substrate Definitely Doesn’t Help!
The Intuitive Picture
Very Efficient Charge Collection!
Heavy Ion (GeV cosmic ray)
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3-D TCAD Modeling
Collaboration with R. Reed of Vanderbilt Univ.and G. Niu of Auburn Univ.
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• Most Charge Collection Occurs Through C/Sx Junction • Long Collection Times for High LET Ion Strikes (nsec!)• Deep Collection Depth (16μm!)
TCAD Charge Dynamics
Collaboration with R. Reed of Vanderbilt and Guofu Niu of Auburn Univ.
Drift Diffusion
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• 3D Simulation I(t), Deep Strike, LET=10, Vsx= -4V (4 GB/s)
8HP 5HP
OUT
DATA
CLOCK
CLOCK
DATA
OUT
“Hit”
Standard Master Slave
RamHard RHBD
UPSETS
TCAD to Circuits
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Dual-Interleaved
• Reduce Tx-Tx Feedback Coupling Internal to the Latch• Circuit Architecture Changes + Transistor Layout Changes
SEU Tolerant Latches
Limiting Cross-section (no errors!)First Successful Hardening of SiGe!
Leverage: DARPA RHBD ProgramDTRA / NEPP
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• Some Reminders
• New Total Dose Effects in Bulk SiGe HBTs
• New Cryogenic Irradiation Results
• New Results on SiGe HBTs on Thin-Film SOI
• A First Look at SiGe MODFETs
• Progress / Plans
Outline
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Source / Rate Effects
• EB spacer SiO2/Si3N4 composite stack • Variation in ∆JB damage with dose rate for different sources not large• Dose enhancement effects apparently observed for x-ray damage
– photon interaction with Cu/W metallization enhanced x-ray damage?– results qualitatively agree with Geant-4 MRED simulations on SRAMs
x-ray dose enhancement
Cu/W studs above EB spacer
Collaboration with MURI Vanderbilt TeamLeverage: DTRA / NEPP
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Source / Rate Effects
• STI oxide thermal CVD (different interface to EB spacer)• Increase in inverse mode ∆JB with dose rate (60Co and x-ray)
– electron-hole pairs escape recombination increased charge yield– secondary electrons generated with low stopping power increased damage
E
B
C
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Reliability Issues
• Preliminary study of possible reliability stress path dependence • Mixed-mode stress (high VCB + high JE) prior to proton irradiation
– 63 MeV protons / 3000 sec mixed-mode stress (JE=40mA/µm2, VCB=3V)• No change observed in post-radiation response after 3000 s of stress
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Reliability Issues
• 1Mrad(SiO2) prior to 3000 sec mixed-mode stress• Forward and inverse mode ∆JB independent of pre-stress condition• More work needed
– increase stress time beyond 3000 sec & vary current density during stress– explore reverse EB stress response
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• Some Reminders
• New Total Dose Effects in Bulk SiGe HBTs
• New Cryogenic Irradiation Results
• New Results on SiGe HBTs on Thin-Film SOI
• A First Look at SiGe MODFETs
• Progress / Plans
Outline
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Temperature: +120C to -180C 28 day cycles -230C in shadowed polar craters
Radiation: 10’s of krad (modest) single event upset (SEU) solar events
Many Different Circuits: digital / analog library ADC / DAC RF power control functions sensor interfaces
The Moon (Classic Extreme Environment!)
Get Rid of the Centralized “Warm Box”
Rover / Robotics
Large GT-led NASA Funded Effort (RHESE) Targeting RLEP-2
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Cryo-T Irradiation
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.21x10-10
1x10-9
1x10-8
1x10-7
1x10-6
1x10-5
1x10-4
1x10-3
1x10-2
Forward Gummel
AE=0.5x1 m2
VCB
=0 V
77 K
300 K
I C, I
B (A
)
VBE
(V)
IC-Prerad
IB-Prerad
IB-100 krad
IB-300 krad
IB-600 krad
IB-1 Mrad
IB-3 Mrad
IB-6 Mrad
100 1000 10000-0.5
0.0
0.5
1.0
1.5
2.0
-0.5
0.0
0.5
1.0
1.5
2.0Forward Mode Gummel
AE=0.5x1 m2
VBE
@IB(Pre)=1 nA
300 K
I B(P
ost)-
IB(P
re) (
nA)
Total Dose (krad(Si))
77 K
• Less Degradation For Devices Irradiated at 77K Compared to at 300K • Damage is Produced Even in the Absence of Significant Thermal Energy
63 MeV protonsLeverage: DTRA / NEPP
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Cryo-T Irradiation
0.4 0.6 0.8 1.0 1.21x10-10
1x10-9
1x10-8
1x10-7
1x10-6
1x10-5
1x10-4
1x10-3
1x10-2
1x10-1
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.21x10-10
1x10-9
1x10-8
1x10-7
1x10-6
1x10-5
1x10-4
1x10-3
1x10-2
1x10-1
5AM SiGe HBTForward Gummel
AE=0.5x2.5 m2
IC-Prerad
IB-Prerad
6 Mrad at 300 K
6 Mrad at77 K
6 Mrad at 77 K
6 Mrad at 300 K 77 K
300 K
I C, I
B (
A)
VBE
(V)
• 300K Irradiation + 77K Measurement vs. 77K Irradiation + 300K Meas.• 300K Irradiation Appears to Produce More Damage Than 77K Irradiation • Interesting Physics AND Bodes Well Lunar Apps of SiGe
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Cryo-T Irradiation
100 1000 100000
1
2
3
4
0
1
2
3
4Forward Mode Gummel
AE=0.12x2 m2
VBE
@IB(Pre)=1 nA
I B(P
ost)
-IB(P
re)
(nA
)
Total Dose (krad(Si))
300 K
77 K
• Answer Appears to Depend on the Technology Node! • In 200 GHz 8HP Devices, Forward-Mode IB is Larger for 77K Irradiation• We Will Focus Some More Attention Here
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• Some Reminders
• New Total Dose Effects in Bulk SiGe HBTs
• New Cryogenic Irradiation Results
• New Results on SiGe HBTs on Thin-Film SOI
• A First Look at SiGe MODFETs
• Progress / Plans
Outline
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• Collector-substrate (n+/p-) Junction Is a Problem• Low Resistivity Substrate (8-10 ohm-cm) Definitely Hurts!
Intuitive Picture for SEU
Very efficient charge collection (to 16 um!)An “obvious” solution – move to SOI!
SOI
J. Pellish et al., NSREC 06
Leverage:DTRA / NEPPNAVSEA
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Device Technology
• IBM Research Collaboration (J. Cai)
• TSi = 120 nm / TBOX = 140 nm (compatible with 130 nm SOI CMOS)
• Substrate Can Be Used as an Active 4th Terminal• True 2-D Device (fundamentally different from conventional SiGe HBT)
VSUB
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X-ray Irradiation
• IB Leakage Increases at Low VBE (EB spacer damage)• IB Decreases at High VBE (RC effect)
Collaboration with MURI Vanderbilt Team
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X-ray Irradiation
• Partially Depleted Devices Irradiated for the First Time• Larger Excess Current with Respect to 63 MeV Protons
FullyDepleted
PartiallyDepleted
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• Some Reminders
• New Total Dose Effects in Bulk SiGe HBTs
• New Cryogenic Irradiation Results
• New Results on SiGe HBTs on Thin-Film SOI
• A First Look at SiGe MODFETs
• Progress / Plans
Outline
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SiGe MODFETs
Collaboration with S. Koester at IBM
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SiGe n-MODFETs
Collaboration with S. Koester at IBM
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nMODFET Irradiation
• Peak gm and peak fT decrease with Radiation
• Impact of Displacement Damage on Transport?
63 MeV protonsLeverage: DTRA / NEPP
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• Many Fundamental Issues in SiGe Need Attention - improve our understanding of basic damage mechanisms (TID + SEU)- understand observed dose enhancement / source dependent effects- understand the effects of operating temperature on damage mechanisms- explore other SiGe HBT variants (e.g., SiGe HBT on SOI, C-SiGe) - explore other (new) SiGe-based devices (e.g., SiGe MODFETs) - improve 3D modeling and understanding for SEU (with R. Reed)- explore metalization / overlayer effects (GEANT4 – with R. Reed)- explore device-to-circuit coupling (mixed-mode TCAD – with R. Reed)
Georgia Tech Focus
• Leverage of Significant SiGe Hardware / Testing Activity - many SiGe tapeouts at Georgia Tech (IBM, Jazz, etc.): devices + circuits- DTRA / NASA-GSFC (NEPP)- DARPA RHBD Program- NASA SiGe ETDP RHESE Program (Lunar apps)
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• Dose Enhancement Effects / Source Dependence in SiGe HBTs - push deeper into the mechanisms: more data + TCAD + GEANT4, etc.
Progress / Plans
• Publications[1] A.K. Sutton, A.P.G. Prakash, R.M. Diestelhorst, G. Espinel, B. Jun, M. Carts, A. Phan, J.D. Cressler, P.W.
Marshall, C.J. Marshall, R.A. Reed, R.D. Schrimpf, and D.M. Fleetwood, “An Investigation of Dose Enhancement and Source Dependent Effects in 200 GHz SiGe HBTs,” IEEE Nuclear and Space Radiation Effects Conference, July 2006.
[2] G. Prakash, R. Diestelhorst, G. Espinel, A. Sutton, B. Jun, C. Marshall, P. Marshall, and J.D. Cressler, “The Effects of 63 MeV Proton Irradiation on SiGe HBTs Operating at Liquid Nitrogen Temperature,” Proceedings of the Seventh IEEE European Workshop on Low-Temperature Electronics, June 2006.
[3] M. Bellini, B. Jun, T. Chen, J.D. Cressler, P.W. Marshall, D. Chen, and J. Cai, “Radiation and Bias Effects in Fully-Depleted and Partially-Depleted SiGe HBTs Fabricated on CMOS-Compatible SOI,” 2006 IEEE Nuclear and Space Radiation Effects Conference, July 2006.
[4] A.P.G. Prakash, A.K. Sutton, R. Diestelhorst, G. Espinel, J. Andrews, B. Jun, J.D. Cressler, P.W. Marshall, and C.J. Marshall, “The Effects of Irradiation Temperature on the Proton Response of SiGe HBTs,” 2006 IEEE Nuclear and Space Radiation Effects Conference, July 2006.
• Explore the Role of Temperature in Damage Physics- push deeper into the mechanisms: more data + TCAD, etc.
• Continue to Push More Deeply into New Types of SiGe Devices- SiGe MODFET; SiGe HBT on SOI; complementary SiGe (npn vs pnp)