John D. Cressler, 6/13/06 1 Radiation Effects in SiGe Devices Bongim Jun, Gnana Prakash, Akil...

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/


• 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


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


Applications

Defense

Navigation

Automotive

Communications


SiGe mm-wave SoC

Wireless 60 GHz (ISM band) Data Links (1.0 Gb/sec!)

Courtesy of Ullrich Pfeiffer of IBM

DARPA Funded


SiGe Radar Systems

Begs For SiGe!

Potential Paradigm Shifting Impact for Phased Array Radar!

Single Chip X-bandSiGe T/R (4x4 mm2)

MDA Funded


Extreme Environments

• Cryogenic Temperatures (e.g., 77K = -196C)• High Temperatures (e.g., 200C)• Radiation (e.g., Earth orbit)

CEV

Drilling

Cars

Aerospace

Moon / Mars


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


• 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!


• 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)


3-D TCAD Modeling

Collaboration with R. Reed of Vanderbilt Univ.and G. Niu of Auburn Univ.


• 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


• 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


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


• 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


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


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


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


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


• Some Reminders






Outline


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


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


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


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


• Some Reminders






Outline


• 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


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


X-ray Irradiation

• IB Leakage Increases at Low VBE (EB spacer damage)• IB Decreases at High VBE (RC effect)

Collaboration with MURI Vanderbilt Team


X-ray Irradiation

• Partially Depleted Devices Irradiated for the First Time• Larger Excess Current with Respect to 63 MeV Protons

FullyDepleted

PartiallyDepleted


• Some Reminders






Outline


SiGe MODFETs

Collaboration with S. Koester at IBM


SiGe n-MODFETs

Collaboration with S. Koester at IBM


nMODFET Irradiation

• Peak gm and peak fT decrease with Radiation

• Impact of Displacement Damage on Transport?

63 MeV protonsLeverage: DTRA / NEPP


• 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)


• 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)

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John D. Cressler, 6/13/06 1 Radiation Effects in SiGe Devices Bongim Jun, Gnana Prakash, Akil...

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