1. John D. Cressler, 6/13/06 1 Radiation Effects in SiGe Devices Bongim Jun, Gnana Prakash, Akil Sutton, Marco Bellini, Ram Krithivasan, and John D. Cressler MURI Review: Vanderbilt University, Nashville, TN June 13, 2006 School of Electrical and Computer Engineering 777 Atlantic Drive, N.W., Georgia Institute of Technology Atlanta, GA 30332-0250 USA cressler@ece.gatech.edu Tel (404) 894-5161 / http://users.ece.gatech.edu/~cressler/

2. John D. Cressler, 6/13/06 2 Rapid Generational Evolution (full SiGe BiCMOS) Making Significant In-roads in High-speed Communications ICs Many DoD-Relevant Opportunities 1 st 2 nd 3 rd 4 th 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

3. John D. Cressler, 6/13/06 3 Half-TeraHertz SiGe HBT! 510 GHz peak f T 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

4. John D. Cressler, 6/13/06 4 Applications Defense Navigation Automotive Communications

5. John D. Cressler, 6/13/06 5 SiGe mm-wave SoC  Wireless 60 GHz (ISM band) Data Links (1.0 Gb/sec!) Courtesy of Ullrich Pfeiffer of IBM DARPA Funded

6. John D. Cressler, 6/13/06 6 SiGe Radar Systems Begs For SiGe! Potential Paradigm Shifting Impact for Phased Array Radar! Single Chip X-band SiGe T/R (4x4 mm 2 ) MDA Funded

7. John D. Cressler, 6/13/06 7 Extreme Environments Cryogenic Temperatures (e.g., 77K = -196C) High Temperatures (e.g., 200C) Radiation (e.g., Earth orbit) CEV Drilling Cars Aerospace Moon / Mars

8. John D. Cressler, 6/13/06 8 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 @ 5x10 13 p/cm 2 = 6.7 Mrad TID! 200 GHz SiGe HBT 3 rd 2 nd 1 st 4 th

9. John D. Cressler, 6/13/06 9 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!

10. John D. Cressler, 6/13/06 10 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)

11. John D. Cressler, 6/13/06 11 3-D TCAD Modeling Collaboration with R. Reed of Vanderbilt Univ. and G. Niu of Auburn Univ.

12. John D. Cressler, 6/13/06 12 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

13. John D. Cressler, 6/13/06 13 3D Simulation I(t), Deep Strike, LET=10, V sx = -4V (4 GB/s) 8HP 5HP OUT DATA CLOCK DATA OUT “Hit” Standard Master Slave RamHard RHBD UPSETS TCAD to Circuits

14. John D. Cressler, 6/13/06 14 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 Program DTRA / NEPP

15. John D. Cressler, 6/13/06 15 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

16. John D. Cressler, 6/13/06 16 Source / Rate Effects EB spacer  SiO 2 /Si 3 N 4 composite stack Variation in ∆J B 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 Team Leverage: DTRA / NEPP

17. John D. Cressler, 6/13/06 17 Source / Rate Effects STI oxide  thermal CVD (different interface to EB spacer) Increase in inverse mode ∆J B with dose rate ( 60 Co and x-ray) –electron-hole pairs escape recombination  increased charge yield –secondary electrons generated with low stopping power  increased damage EBCEBC

18. John D. Cressler, 6/13/06 18 Reliability Issues Preliminary study of possible reliability stress path dependence Mixed-mode stress (high V CB + high J E ) prior to proton irradiation –63 MeV protons / 3000 sec mixed-mode stress (J E =40mA/µm 2, V CB =3V) No change observed in post-radiation response after 3000 s of stress

19. John D. Cressler, 6/13/06 19 Reliability Issues 1Mrad(SiO 2 ) prior to 3000 sec mixed-mode stress Forward and inverse mode ∆J B independent of pre-stress condition More work needed –increase stress time beyond 3000 sec & vary current density during stress –explore reverse EB stress response

20. John D. Cressler, 6/13/06 20 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

21. John D. Cressler, 6/13/06 21 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

22. John D. Cressler, 6/13/06 22 Cryo-T Irradiation Less Degradation For Devices Irradiated at 77K Compared to at 300K Damage is Produced Even in the Absence of Significant Thermal Energy 63 MeV protons Leverage: DTRA / NEPP

23. John D. Cressler, 6/13/06 23 Cryo-T Irradiation 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

24. John D. Cressler, 6/13/06 24 Cryo-T Irradiation Answer Appears to Depend on the Technology Node! In 200 GHz 8HP Devices, Forward-Mode  I B is Larger for 77K Irradiation We Will Focus Some More Attention Here

25. John D. Cressler, 6/13/06 25 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

26. John D. Cressler, 6/13/06 26 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 / NEPP NAVSEA

27. John D. Cressler, 6/13/06 27 Device Technology IBM Research Collaboration (J. Cai) T Si = 120 nm / T BOX = 140 nm (compatible with 130 nm SOI CMOS) Substrate Can Be Used as an Active 4 th Terminal True 2-D Device (fundamentally different from conventional SiGe HBT) V SUB

28. John D. Cressler, 6/13/06 28 X-ray Irradiation I B Leakage Increases at Low V BE (EB spacer damage) I B Decreases at High V BE (R C effect) Collaboration with MURI Vanderbilt Team

29. John D. Cressler, 6/13/06 29 X-ray Irradiation Partially Depleted Devices Irradiated for the First Time Larger Excess Current with Respect to 63 MeV Protons Fully Depleted Partially Depleted

30. John D. Cressler, 6/13/06 30 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

31. John D. Cressler, 6/13/06 31 SiGe MODFETs Collaboration with S. Koester at IBM

32. John D. Cressler, 6/13/06 32 SiGe n-MODFETs Collaboration with S. Koester at IBM

33. John D. Cressler, 6/13/06 33 nMODFET Irradiation Peak g m and peak f T decrease with Radiation Impact of Displacement Damage on Transport? 63 MeV protons Leverage: DTRA / NEPP

34. John D. Cressler, 6/13/06 34 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)

35. John D. Cressler, 6/13/06 35 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)