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1John D. Cressler, 5/09
SiGe Technology:New Research Directions and
Emerging Application Opportunities
John D. CresslerKen Byers Professor
School of Electrical and Computer EngineeringGeorgia Tech, Atlanta, GA 30332-0250 USA
IEEE Southeastern Michigan Chapter IV, Ann Arbor, MI, May 2009IEEE Electron Devices Society Distinguished Lecture
This work was supported by NASA, DTRA, IBM, DARPA, JPL, TI, and NSC
2John D. Cressler, 5/09
3John D. Cressler, 5/09
A few monolayersof SiGe Goes Here… Very Carefully!
A Level-Set on Miracles
4John D. Cressler, 5/09
Outline
• Some Reminders on SiGe• Scaling Trends and Performance Limits• Using SiGe for Radar Systems • Using SiGe for High-speed Analog • Using SiGe in Extreme Environments • Summary
5John D. Cressler, 5/09
Practice Bandgap Engineering … but do it in Silicon!
SiGe Strained Layer Epi
ΔEV
The Bright Idea!
6John D. Cressler, 5/09
• Seamless Integration of SiGe into Si
When You Do It Right …
No Evidenceof Deposition!100 nm
7John D. Cressler, 5/09
The SiGe HBT
The Idea: Put Graded Ge Layer into the Base of a Si BJT
Primary Consequences:• smaller base bandgap increases electron injection (β )• field from graded base bandgap decreases base transit time (fT ) • base bandgap grading produces higher Early voltage (VA )• decouples base profile from performance metrics
SiGe = III-V Speed + Si Manufacturing: Win-Win!
8John D. Cressler, 5/09
The SiGe HBT
E B C
SiGe50 nmSiGe = III-V Speed + Si ManufacturingWin-Win!
• Conventional Shallow and Deep Trench Isolation + CMOS BEOL• Unconditionally Stable, SiGe Epitaxial Base Profile• 100% Si Manufacturing Compatibility• SiGe HBT + Si CMOS on wafer
9John D. Cressler, 5/09
SiGe Success Story
1G
2G
3G
4G
• Rapid Generational Evolution (full SiGe BiCMOS)• Significant In-roads in Communications / Analog ICs
Important Point: 200 GHz @ 130 nm! (2G better than CMOS)
(130 nm)
(180 nm)
(500 nm)
10John D. Cressler, 5/09
SiGe Apps
Defense
Navigation
Automotive
Communications 1999 2000 2001 2002 2003 2004 2005 20060.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Wor
ldw
ide
Chi
p Sa
les
In Billions of US $ SiGe, CAGR = 61.3% GaAs, CAGR = 8.7%
Years
Defense
Navigation
Automotive
Communications
SiGe Analog/MS ICs Are a Major Driver!
11John D. Cressler, 5/09
• SiGe for Radar Systems- single chip T/R for phased arrays, space-based radar (2-10 GHz & up) - automotive radar (24, 77 GHz)
• SiGe for Millimeter-wave Communications - Gb/s short range wireless links (60, 94 GHz)- cognitive radio / frequency-agile WLAN / 100 Gb Ethernet
• SiGe for THz Sensing, Imaging, and Communications - imaging / radar systems, diagnostics, comm (94 GHz, 100-300 GHz)
• SiGe for Analog Applications- the emerging role of C-SiGe (npn + pnp) + data conversion (ADC limits)
• SiGe for Extreme Environment Electronics- extreme temperatures (4K to 300C) + radiation (e.g., space systems)
• SiGe for Electronic Warfare - extreme wideband transceivers (20 MHz – 20 GHz)- dynamic range enhanced receivers
Some New Opportunities
12John D. Cressler, 5/09
• SiGe for Radar Systems- single chip T/R for phased arrays, space-based radar (2-10 GHz & up) - automotive radar (24, 77 GHz)
• SiGe for Millimeter-wave Communications - Gb/s short range wireless links (60, 94 GHz)- cognitive radio / frequency-agile WLAN / 100 Gb Ethernet
• SiGe for THz Sensing, Imaging, and Communications - imaging / radar systems, diagnostics, comm (94 GHz, 100-300 GHz)
• SiGe for Analog Applications- the emerging role of C-SiGe (npn + pnp) + data conversion (ADC limits)
• SiGe for Extreme Environment Electronics- extreme temperatures (4K to 300C) + radiation (e.g., space systems)
• SiGe for Electronic Warfare - extreme wideband transceivers (20 MHz – 20 GHz)- dynamic range enhanced receivers
Some New Opportunities
13John D. Cressler, 5/09
SiGe HBT vs CMOS
• If Cost Were No Object, III-V Devices Would Always DominateSi-based Solutions in Terms of Raw Speed and Breakdown Voltage,BUT … Integration and Cost Increasingly Decide Things …
• Clearly Both SiGe HBTs and (Strained-Si) CMOS Are Capable of Very Frequency Operation, BUT That Is Not the Whole Story …
Some Key Advantages SiGe HBTs Have Over CMOS:- for equal performance, SiGe requires less aggressive lith (2 gen)- lith delta = cost delta (130 nm SiGe costs less than 65 nm CMOS) - SiGe HBTs give higher BV’s at fixed performance (BVCEO vs BVCBO)- SiGe HBTs are better for generating CW power at fixed frequency- gm/µm2 is MUCH larger for SiGe HBTs (need BIG nFETs for high fmax)- 1/f noise is 100x lower in SiGe HBTs; much better matching- SiGe HBTs have better output conductance at fixed scaling node- modeling of SiGe HBTs is easier for high-frequency design - SiGe HBTs have built-in total dose radiation hardness for space- SiGe HBTs are natural for mixed-signal & BiCMOS = HBTs + CMOS
Some Thoughts on the Matter …
My Opinion: SiGe BiCMOS at a More Conservative Node Is Often Better Suited for MANY Applications Than Aggressively-Scaled CMOS
14John D. Cressler, 5/09
Strain Engineering in Si
Strained Si CMOS SiGe HBTs
SiGe MODFETs
All Are:Strain-Enhanced
Si-based Transistors
Close Cousins!
15John D. Cressler, 5/09
Some Morals to the Story:
1) CMOS is Cheaper Than SiGe at Fixed Scaling Node2) SiGe is Cheaper Than CMOS at Fixed Performance3) SiGe HBTs are More “Natural” for RF/Analog Design4) BiCMOS Often is Optimal for Integrated Solutions
Q: Where is SiGe the Best Fit?
16John D. Cressler, 5/09
Outline
• Some Reminders on SiGe• Scaling Trends and Performance Limits• Using SiGe for Radar Systems • Using SiGe for High-speed Analog • Using SiGe in Extreme Environments • Summary
17John D. Cressler, 5/09
TeraHertz Applications
Pic. avail. at http://www.advancedphotonix.com/
• Imaging for Quality Control • Detection of Non-Metallic Objects • Medical Diagnostics• Radio Astronomy• Ultra-Wideband Communications (fast and secure)• THz Active Circuits + ICs ??
300 GHz
Emerging THz Electronics Applications (100-300 GHz)
18John D. Cressler, 5/09
• Cooling a SiGe HBT Emulates Vertical + Lateral Scaling- vsat , RB , and CCB as T better current drive, parasitics
- and … Ge grading (∆Eg,Ge(grade)/kT) more effective as T
Cryo-T as a Scaling Knob
• Classical Scaling (300K):- vertical: NC , NB , WB
Pros: τE, τC, τCSCL, and τΒCons: CCB and RB , BVCEO
- lateral:Pros: RB , CCB and CEB
Cons: RE and RC
- innovation needed …- moral: scaling isn’t free!
300 K
19John D. Cressler, 5/09
• fT + fmax > 1 THz in SiGe Is Clearly Possible (at very modest lith)• Both fT and fmax above 500 GHz at Cryo-T (T = scaling knob) • Goal: Useful BV @ 500 GHz (BVCEO > 1.5 V + BVCBO > 5.5 V)
SiGe Performance Limits
8HP
200-500 GHz @ 130 nm Node!
20John D. Cressler, 5/09
• A 300K Scaling Roadmap for SiGe HBTs
Can We Do This at 300K?
e.g., EU “DOT5”Project
21John D. Cressler, 5/09
Outline
• Some Reminders on SiGe• Scaling Trends and Performance Limits• Using SiGe for Radar Systems • Using SiGe for High-speed Analog • Using SiGe in Extreme Environments • Summary
22John D. Cressler, 5/09
DoD Radar T/R Modules
• X-Band Phased Array Radar - realized with III-V MMICs, assembled into T/R MCMs ($1k each)- employs high power density approach (1 MW to run 25k HPD T/R modules)- costly to deploy and operate
25,000 high power multi-chip modules
1 MW diesel generator
liquid/air heat
exchanger
1990’s
Courtesy of M. Mitchell
T/RTHAADRadar
23John D. Cressler, 5/09
A New DoD Radar Vision
• A New Radar Paradigm- panel based + uses low power density approach (reduced prime power)- T/R = low-cost + efficient + highly integrated (with digital control)
The Future
SiGe T/R
Multi-ChipPanel
Multi-Panel Array
Courtesy of M. MitchellBegs for a SiGe BiCMOS Solution!
24John D. Cressler, 5/09
RF Manifold
In/Out
PA
From Radiator-A
T/R Module Topology
From Radiator-B
3-bitPhase Shifter
Pre-AmpPre-Gain
SP3TSwitch
LNA-B
LNA-ALNA
SwitchSwitch
1-bitPhase Shifter
4-bit Phase Shifterwith integrated LNA
RX Mode Challenges- need very aggressive LNA- must balance gain, linearity, and NF- need low power dissipation- need a good phase shifter
TX Mode Challenges- must deliver necessary output power- need high power efficiency- need high gain + stability
BiCMOS Design OptimumSiGe is an Ideal FitSingle chip solution
25John D. Cressler, 5/09VCC = 2.5 V, IC = 6 mA = 15 mW
X-band LNA
1.5 dB
• Radar Spec Demands NF < 2.0 dB Across Band
26John D. Cressler, 5/09
• Compare MOS Phase Shifter to HBT Phase Shifter• Maintain Same Design Methodology
- target 4-bit phase shifter- use similar HP and LP filter sections- utilize meander layout for reasonable aspect ratio
MOS vs HBT Shifters
HBT MOS
27John D. Cressler, 5/09
SiGe PA Design Issues• Understand Voltage Constraints / Instabilities• Leverage CB-forced IE Mode for PA Voltage Swing • Power Cell Layout Optimization For Thermal Coupling
125 mW / 40 dB gain 25% PAE X-band PAHP + HB Cascode
850 mW / 11 dB gain 18% PAE X-band PAHP + HB Cascode
28John D. Cressler, 5/09
SiGe T/R Results
• Pout > 22 dBm• P1dB > 20 dBm• TX Gain > 17 dB• PAE = 28%
• NF < 3.5 dB• RX Gain > 15 dB• IIP3 = -10 dBm
RX TX
RX TX
13 mm2
29John D. Cressler, 5/09
SiGe Automotive Radar
• 24 GHz Short Range Radar + 77 GHz Long Range Radar - nice fit for SiGe technology (2G SiGe for SRR + 3G SiGe for LRR) - in the EU 24G SRR works until 2013, and then moves to 79G (LRR = 77G)
Courtesy of SARA
SRR LRR
Integration is Key
30John D. Cressler, 5/09
A Future SiGe Radar Path
Multilayer OrganicSubstrate (LCP)
Embedded SiGe T/RCircuits
Integrated RF MEMS Phase Shifters
IntegratedSiGe T/Ron Flexible Multilayer OrganicSubstrate
• 3D X-band to mm-wave SiGe Integrated Radars- flexible + low-cost + multilayer + wafer scale - RF MEMS phase shifters + antennae- for space-based radar & comm systems
85 90 95 1002
4
6
8
10
12
14
Measured Gain & Noise Figure
Gain
NF
Frequency (GHz)
W-band SiGe LNA
P1dB = -12.5 dBmIIP3 = -8 dBm
Collaboration with John Papapolymerou and Kevin Kornegay
Gai
n an
d N
oise
(dB
)
31John D. Cressler, 5/09
Outline
• Some Reminders on SiGe• Scaling Trends and Performance Limits• Using SiGe for Radar Systems• Using SiGe for High-speed Analog • Using SiGe in Extreme Environments • Summary
32John D. Cressler, 5/09
C-SiGe Leverage
Q: Complementary SiGe HBT Technology (C-SiGe)?
• Some Possibilities:- address “issues” analog C-Si BJTs have inherent trouble with:
- achieving high current gain for both npn + pnp- achieving high speed for both npn + pnp- achieving high output resistance for both npn + pnp- decoupling gain / speed / VA from base profile design
- enables a future performance scaling path for analog IC apps
MANY Intriguing Possibilities …
Fact: C-Si BiCMOS (npn + pnp) is the Gold Standard for High-performance Analog ICs (high value add)
33John D. Cressler, 5/09
TI’s BiCOM3X C-SiGe
• Balanced 25 GHz fT / 60 GHz fmax, 6V BVCEO C-SiGe Platform • Thick Film SOI for Isolation• Being Used Leading-Edge Analog Parts (500 MS/s 14 bit ADC)
npn SiGe HBT
pnp SiGe HBT npn SiGe HBT
34John D. Cressler, 5/09
IHP C-SiGe Technology
• IHP’s C-SiGe HBT Technology- low RC and CCS collector construction (no STI between E and C)- reduced phosphorus diffusion in the C-doped base- npn SiGe HBT: peak fT / BVCEO of 170 GHz / 1.9 V- pnp SiGe HBT: peak fT / BVCEO of 90 GHz / 3.1 V (60 / 4.5)-
npn SiGe HBT
pnp SiGe HBT
[2] D Knoll et al, BCTM, pp. 30-33, 2007[1] B. Heinemann et al, IEDM, pp. 117-120, 2003
35John D. Cressler, 5/09
ADC Migration
Major Stressor on ADC Performance
36John D. Cressler, 5/09
40 GS/s Track/Hold Amp
37John D. Cressler, 5/09
Outline
• Some Reminders on SiGe• Scaling Trends and Performance Limits• Using SiGe for Radar Systems • Using SiGe for High-speed Analog • Using SiGe in Extreme Environments • Summary
38John D. Cressler, 5/09
Extreme Environments
• Aerospace (aircraft, satellites ...)• Space Exploration (Moon, Mars ...)• Automotive (on-engine …)• Drilling (oil, geothermal ...)
Exploration
DrillingCars
Aerospace
Extreme Environment Electronics:low-T, high-T, wide-T, radiation, shock, chemical …
39John D. Cressler, 5/09
Moon Mars Outer Planets
Space Exploration
All Represent Extreme Environments!(Very Wide Temperature Swings + Radiation)
40John D. Cressler, 5/09
Temperature Ranges:+120C to -180C (300C swings!)28 day cycles
Radiation:100 krad over 10 yearssingle event upset (SEU)solar events
Many Different Circuit Needs:digital building blocksanalog building blocksdata conversion (ADC/DAC)RF communicationspower conditioningactuation and controlswitchessensors / sensor interfaces
Requires Centralized “Warm Box”
Rovers / Robotics
The Moon:A Classic Extreme Environment!
Highly Mixed-Signal Flavor!
41John D. Cressler, 5/09
The Idea: Put Graded Ge Layer into the Base of a Si BJT
Primary Consequences:• smaller base bandgap increases electron injection (β )• field from graded base bandgap decreases base transit time (fT )• base bandgap grading produces higher Early voltage (VA )
All kT Factors Are Arranged to Help at Cryo-T!
SiGe HBTs for Cryo-T
42John D. Cressler, 5/09
SiGe HBTs at Cryo-T
27C
-230C
dc ac
SiGe Exhibits Very High Speed at Very Low Power!
First Generation SiGe HBT
43John D. Cressler, 5/09
X-band LNA Operation at 15 K (Not Yet Optimized!)
• Teff < 20 K (noise T)• NF < 0.3 dB• Gain > 20 dB• dc power < 2 mW
Cryogenic SiGe LNAs
Collaboration with S. Weinreb, Cal Tech
NF = 0.3 dB!
This SiGe LNA is Also Rad-Hard!
44John D. Cressler, 5/09
SiGe at High-T? (200-300C)
• Degradation, But Plenty of Performance Left!• Device Reliability Looks Fine • Just in: Robust Operation @ 300C for Selected Circuits
Gain Frequency
45John D. Cressler, 5/09
• The Holy Grail of the Space Community- IC technology space-qualified without additional hardening (major cost adder)- high integration levels to support SoC / SiP (low cost)
SiGe For Space Systems
proton + electron belts
Major Question: Can SiGe Play a Major Role in Space?
• Total Ionizing Dose (TID) – ionizing radiation- TID is measured in “rads” (1 rad = 100 ergs per gram of energy absorbed)- 100-1000 krad(Si) over 10 years for typical orbit (300 rad(Si) is lethal to humans!)
• Single Event Upset (SEU) – high energy heavy ions- measure data upset cross-section (σ) vs. Linear Energy Transfer (LET)- σ = # errors / particle fluence (ions/cm2): LET = charge deposition (pC/μm)- Goals: low cross-section + high LET threshold
46John D. Cressler, 5/09
Total-Dose Response• Multi-Mrad Total Dose Hardness (with no intentional hardening!)
- ionization + displacement damage very minimal over T; no ELDRS!• 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
47John D. Cressler, 5/09
• 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
Goal…
Single Event Effects
heavy ion
48John D. Cressler, 5/09
OUT
DATA
CLOCK
“TCAD Ion Strike”
Standard Master Slave Latch UPSETS
SEU: TCAD to Circuits
New RHBD SiGe Latch
SEU “Soft”
49John D. Cressler, 5/09
• Reduce Tx-Tx Feedback Coupling Internal to the Latch• Circuit Architecture Changes + Transistor Layout Changes
SiGe RHBD Success!
Future - Eliminate TMR & Be Faster!Path - Build a Rad-Hard System!
(no errors!)
50John D. Cressler, 5/09
Remote Electronics Unit
• 5” x 3” x 6.75” = 101 in3
• 11 kg• 17 Watts • -55oC to +125oC
• 1.5” x 1.5” x 0.5” = 1.1 in3 (100x)• < 1 kg (10x)• < 2 Watts (10x)• -180oC to +125oC, rad tolerant
Conceptual integrated REU system-on-chip SiGe BiCMOS die
The X-33 Remote Health Unit, circa 1998
The ETDP Remote Electronics Unit, circa 2009
Specifications Goals
Analog front end die
Digital control die
Supports Many Sensor Types:Temperature, Strain, Pressure, Acceleration, Vibration, Heat Flux, Position, etc.
REU in connector housing!
Use This REU as a Remote Vehicle Health Monitoring Node
51John D. Cressler, 5/09
Temperature Controlled Environment
System Processor
(RAD750 or equivalent)
Solid State Data Recorder
Extreme Ambient Environment
Extreme Ambient Environment
Communications
Accelerometer (High sp)
Accelerometer (ch amp)
Thermocouple (Low sp)
Thermocouple (Low sp)
Thermocouple (Low sp)
Thermocouple (Low sp)
Pressure Transducer
(Low sp)
Pressure Transducer
(Low sp)
REU Digital Control ASIC
REU Sensor
Interface ASIC
Ctrl
Data
Sensor Inputs
RS-485
REU in Connector Housing
Boot PROM
REU Digital Control ASIC
REU Sensor
Interface ASIC
Ctrl
Data
Sensor Inputs
RS-485
REU in Connector Housing
Boot PROM
REU Digital Control ASIC
REU Sensor
Interface ASIC
Ctrl
Data
Sensor Inputs
RS-485
REU in Connector Housing
Boot PROM
REU Digital Control ASIC
REU Sensor
Interface ASIC
Ctrl
Data
Sensor Inputs
RS-485
REU in Connector Housing
Boot PROM
REU Sensor
Interface ASIC
REU Digital Control ASIC
Data
CtrlSensor Inputs
RS-485
REU in Connector Housing
Boot PROM
REU Sensor
Interface ASIC
REU Digital Control ASIC
Data
CtrlSensor Inputs
RS-485
REU in Connector Housing
Boot PROM
REU Sensor
Interface ASIC
REU Digital Control ASIC
Data
CtrlSensor Inputs
RS-485
REU in Connector Housing
Boot PROM
REU Sensor
Interface ASIC
REU Digital Control ASIC
Data
CtrlSensor Inputs
RS-485
REU in Connector Housing
Boot PROM
Major Advantages:• Eliminates Warm Box (size, weight, and power; allows de-centralized architecture)• Significant Wiring Reduction (weight, reliability, simplifies testing & diagnostics)• Commonality (easily adapted from one system to the next)
SiGe REU Architecture
52John D. Cressler, 5/09
MISSE-6 ISS Mission
Recent NASA photograph of MISSE-6 after deployment, taken by the Space Shuttle Crew
SiGe Circuits !
53John D. Cressler, 5/09
Summary
The Global Landscape:• The Emerging Communications Infrastructure
- frequency bands pushing upward over time (stresses device design)- integration of RF + digital + analog + passives increasingly important- SiGe HBT BiCMOS is well-positioned to address this market
SiGe Technology is Here to Stay!
SiGe HBT BiCMOS Technology:• The SiGe HBT is the First Practical Bandgap Engineered Device in Si• Compared to Si BJTs, SiGe HBTs Offer Better:
- β + VA + βVA + fT + fmax + 1/f + NFmin + …• Compared to CMOS, SiGe HBTs Offer Better:
- fT/fmax/NF at fixed scaling node + matching + gm/area + 1/f noise, + …• Still Room for Lots of Performance Improvement (fT / fmax = 500 GHz)• Still Lots to Learn About the Physics of These Interesting Devices• MANY Interesting Application Possibilities and New Opportunities!
54John D. Cressler, 5/09
My Gang at Georgia Tech