SiGe:C BiCMOS Technologies for RF Automotive Application Gerhard Fischer, Srdjan Glisic, Bernd Heinemann, Dieter Knoll, Wolfgang Winkler IHP Im Technologiepark 25 15236 Frankfurt (Oder) Germany
Outline IHP Frankfurt (Oder) Application: automotive radar sensors IHP technologies: Low-cost SiGe:C BiCMOS for 24 GHz front-end receiver High-performance SiGe:C BiCMOS for 77/79 GHz transmitter High temperature stability and reliability
IHP Frankfurt (Oder) Founded 1972 Institut für Halbleiterphysik of the East German Academy of Science 1991 Member of the Blaue Liste (later Leibniz Society) 1999: Innovations for High Performance Microelectronics 900 m² class 1 clean room, staff: ~ 200 co-workers 4 core competencies: Materials research, Si process technology, rf circuit design, wireless communication systems
IHP Technology Portfolio Platform 0.25 µm CMOS with 4 or 5 Al metal layers, 1 ff/µm² MIM capacitors (> 1 ff/µm² high-k MIM in development), different resistors SiGe:C hetero bipolar transistors (HBT) Technologies Technology SGB25VD SG25H1 SG25H2 SG25H3 Object Low-Cost BiCMOS w/ LV/MV/HV HBTs High Performance BiCMOS Complementary BiCMOS w/ npn + pnp HBTs Multi Purpose BiCMOS w/ LV/MV/HV HBTs 0.13 µm BiCMOS technology with f T /f max > 200 GHz is in development technologies are offered in multi-wafer project (MPW) shuttle service
Application: Automotive Radar Sensors Short range radar (SRR) Frequency: 24 GHz or 79 GHz Bandwidth: up to 4 GHz Distance: 0 30 m Parking aid Blind spot detection Long range radar (LRR) for Autonomous Cruise Control (ACC) Precrash Backup parking aid ACC for Stop & Go Rear crash collision warning Frequency: 76.5 GHz Bandwidth: 200 MHz Distance: > 5m Collision warning Collision mitigation Blind spot detection Lane change assistent Radar technology allows control of car surroundings enables new applications for passive and active safety total system needs up to 8 SRR and 1 ACC sensors
Application: Radar Front-end Transceiver Example: 77/79 GHz with high-performance BiCMOS Example: 24 GHz with low-cost BiCMOS No technology modification for automotive application!
Example 24 GHz LNA Low-Cost SiGe:C BiCMOS
Low-Cost Technology SGB25VD Platform 0.25 µm CMOS with 4 metal layers (3 µm thick 5 th Al layer optional) 3 SiGe:C hetero bipolar transistors (HBT) Devices (selection) Device ft/fmax/bvceo [GHz/GHz/V] Low-voltage HBT f T /f max = 75/90 GHz, BV CEO = 2.4V, BV CBO = 7.7V Medium-voltage HBT High-voltage HBT NMOS Varactor MIM Capacity Resistors Predefined Inductors f T /f max = 45/90 GHz, BV CEO = 4V, BV CBO = 17V f T /f max = 25/70 GHz, BV CEO = 7V, BV CBO > 20V C = 2.3 7 ff/µm², Q = 25 75 @ 5GHz C = 1 ff/µm², BV > 30 V R S = 310 Ohm (p + -poly) R S = 2000 Ohm (low doped poly) L = 0.94 23.8 nh
Medium-Voltage HBT: X-section Features of SGB25VD bipolar module Only shallow trench isolation (STI) SiO 2 L-Spacer Si/SiGe:C/Si Epi Layer Poly-Si Gate Layer CoSi 3 HBT types by collector implant variation HBT integration after gate stack deposition 1-mask HBT module Poly-Si CMP for emitter external base isolation Emitter area: 0.42x0.84 µm² SIC Coll. Well Deep P Implant (SC) n-well S/D SIC: Selectively implanted collector S/D: Source/drain implant
Medium-Voltage HBT: RF Characteristics f T, f max [ GHz ] 120 110 100 90 80 70 60 50 40 30 20 10 0 V CE = 2.5V 4x(0.42x0.84) µm² 16x(0.42x0.84) µm² 0.1 1 10 IC [ ma ] HBT emitter area variants in design kit: A E = N xy x 0.42 µm x L Emitter N xy = 1 16 L Emitter = 0.84 3.36 µm
Medium-Voltage HBT: RF Noise Fmin (db) 2.5 2.4 2.3 2.2 2.1 @24GHz 10 8 6 4 2 Associated Gain [ db ] V CE = 3V Emitter area = 16x0.42x0.84 µm² Minimum noise figure: @ 2 GHz ~ 0.5 db @ 24 GHz ~ 2.1 db 2.0 0 1 2 Collector Current (ma) 0
24GHz Receiver Front End: LNA Noise Figure [ db ] 14 12 10 8 6 F min F 50Ω 4 2 0 5 10 15 20 25 30 Frequency [ GHz ] 22 20 18 16 14 12 10 8 6 4 Associated Gain [ db ] V CC = 5V I CC = 6.3 ma @ 24 GHz: F min ~ F 50Ω ~ 4.5 db G a = 16 db
Example 77/79 GHz VCO High-Performance SiGe:C BiCMOS
High-Performance Technology SG25H1 Platform 0.25 µm CMOS with 4 metal layers (3 µm thick 5 th Al layer optional) 2 SiGe:C hetero bipolar transistors (HBT) Devices (selection) Device HBT npn200 HBT npn201 ft/fmax/bvceo [GHz/GHz/V] f T /f max = 190/190 GHz, BV CEO = 1.9V, BV CBO = 4.5V f T /f max = 180/220 GHz, BV CEO = 1.9V, BV CBO = 4.5V
High-Performance HBT: X-section Features of SG25H1 bipolar module CoSi emitter contact Only shallow trench isolation (STI) HBT integration after gate module Uniform active area 30nm boron doped Si 0.8 Ge 0.2 C 0.002 n doped poly crystalline Si emitter CoSi base contact poly crystalline SiGe:C extrinsic base CoSi collector contact Combination of selective and differential Si/SiGe:C/Si epitaxy Drawn emitter area: 0.21x0.84 µm² (npn200) 0.18x0.84 µm² (npn201) SiO 2 Trench STI S/D n + SiO 2 SIC n + n doped Si collector 2 µm bipolar window p - Si substrate SiO 2 SIC: Selectively implanted collector S/D: Source/drain implant
High-Performance HBT: DC Gummel Characteristic I B, I C [A] 10 0 250 10-1 V CB = 0V 10-2 10-3 200 10-4 10-5 150 10-6 10-7 100 10-8 10-9 HBT 10-10 npn200 50 10-11 npn201 10-12 0.4 0.5 0.6 0.7 0.8 0.9 0 1.0 V BE [V] Beta
High Performance HBT: DC Output Characteristic 5.0 4.0 npn200 I C / Emitter [ ma ] 3.0 2.0 1.0 maximum f T 0.0 I E = 0 (-0.5mA) -4mA -1.0-1 0 1 2 3 V CB [ V ] Breakdown voltage with soft breakdown criterion: IC = 100 na BVCBo = 4.5V IC = 10 ua BVCBo = 5.5V
High Performance HBT: Transit Frequency f T f T [ GHz ] 220 200 180 160 140 120 100 80 60 40 20 0 Extrapolation @ 30 GHz V CE = 1.5V 1 10 I C [ ma ] HBT npn200 npn201 f max [ GHz ] 220 200 180 160 140 120 100 220 80 200 180 60 160 40 140 20 120 0 100 80 60 40 20 0 Extrapolation @ 30 GHz V CE = 1.5V HBT npn200 npn201 1 10 220 200 180 160 140 120 100 80 60 40 20 0 I C [ ma ]
High Performance HBT: Gate Delay Time τ RO Gate Delay Time (ps) 7 6 5 4 3 npn201 A E = 0.18x0.84µm 2 npn200 A E = 0.21x0.84µm 2 T= 300K ΔV= 300mV V EE = -2.5V Standard Extr. Base Elevated Extr. Base Optimization τ RO Elevated extrinsic base (Rücker et al., IEDM 2003) Collector pedestal 3.2 ps (Heinemann et al., IEDM 2004) 1 10 2 0 Current per Gate (ma) 2000 2001 2002 2003 2004 Gate Delay Time [ ps ] 14 12 10 8 6 4 Year Hitachi IBM Infineon IHP
Application: Radar Project KOKON 2004 formation of BMBF funded project KOKON Goals: Investigation of systems for automotive radar sensors at 76 81 GHz Definition of SiGe technology for - long range radar (LRR) system at 76 77 GHz - ultra-wide band short range radar (UWB-SRR) at 77 81 GHz Development of circuits for cost-efficient LRR and SRR sensors Prototyping a full electronic cocoon ( KOKON ) around the car IHP is subcontractor of Infineon and Atmel in BMBF project KOKON Homepage: www.kokon-project.com
Application: Radar Core Circuit Core circuit for radar signal generation: Voltage controlled oscillator (VCO) + power amplifier (PA) Realization in KOKON: SiGe:C bipolar process (Infineon) with BC varactors SiGe:C BiCMOS process (IHP) with NMOS accumulation varactors Goal: Analysis of impact of technological platform on circuit performance 0.8 mm 0.5 mm IHP 77 GHz VCO + PA + metal 5 transmission line inductors differential design 1-stage output buffer 2-stage output buffer (tbd)
Application: Radar Specifications VCO + PA Parameter Center frequency Tuning sensitivity Tuning range Output power Phase noise Amplitude noise Target 77 GHz ~ 2 GHz/V 10 GHz +16 dbm (40 mw) 2-stage output buffer < -75 dbc/hz @ 100kHz Offset < -160 dbc/hz @ 10 khz Offset Other boundary conditions: Environmental temperature Supply voltage - 40 C... +125 C + 5.5V, VCC
Application: Radar Properties VCO Oscillator Frequency [ GHz ] 78 77 76 75 74 73 72 71 70 69 2 4 6 8 Standard deviation over wafer (10 chips): +/- 0.14 GHZ tuning range ~ 8 GHz Standard deviation over wafer (10 chips): +/- 0.67 dbm 2 4 6 8 1 0-1 -2-3 -4 Output Power [ dbm ] Technology: SG25H1 (w/ npn200) Output power (singleended measurement): -1.2 +/- 0.4 dbm Control Voltage [ V ]
Application: Radar Properties VCO + 1-stage Buffer Oscillator Frequency [ GHz ] 82 81 80 79 78 77 76 75 74 73 tuning range ~ 7 GHz with npn201 with npn200 2 3 4 5 Control Voltage [ V ] 16 15 14 13 12 Output Power [ dbm ] Technology: SG25H1 (w/ npn201 and npn200) f max difference: 20 GHz Output Power difference: ~ 0.8 dbm Full output power 1-stage buffer ~ 14 dbm 2-stage buffer ~ 18 dbm (expected)
Application: Radar Properties VCO + 1-stage Buffer 17 250 Technology: SG25H1 (w/ npn201) P out [ db ] 16 15 14 200 150 I CC [ ma ] HBT: 8x0.18x0.84 µm 2 Maximum size in design kit P out > 16 dbm @ V CC = 6.5V 13 100 5 6 7 Supply Voltage V CC [ V ] Power dissipation @ V CC = 5.5 V P diss = 900 mw
High Temperature Stability and Reliability
Application: KOKON Sensitivity Analysis Oscillator Frequency f osc [ GHz ] 81 80 79 78 base resistance collector base capacity forward transit time ~ 1/f T oxide thickness (inductor) BC capacity 77 (CBC) Forward transit time (TF) 76-60% -40% -20% 0% 20% 40% 60% Relative Change Changing inductivity or SPICE parameters in simulation leads to following sensitivities: Parameter Oxide thickness (Inductor) Base resistance (RB) MHz / %shift -135-45 -38-35.5
Application: KOKON Sensitivity Analysis Parameter Simulation MHz / %shift Measurement %shift / 100K Shift of f osc [MHz/100K] Oxide thickness - 135 + 0.1% -13.5 (Inductor) Base resistance -45 + 5% - 225 (RB) BC capacity (CBC) -38 + 4% - 150 Forward transit time (TF) -35.5 + 25% - 890 Sum ~ - 1300 Estimation gives a reduction of oscillator frequency of at least 1.3 GHz/100K
Temperature Stability VCO Oscillator Frequency [ GHz ] 80 79 78 77 76 75 74 73 tuning range temperature shift 72-40 -20 0 20 40 60 80 100 120 140 Temperature [ C ] Chip A Chip B Chip C Technology: SG25H1 (npn200) Temperature shift Δf = f Osz,RT f Osz,125 C ~ 1.8 GHz
Oscillator Operation Transistor Reliability I C / Emitter [ ma ] 5.0 4.0 3.0 2.0 1.0 npn200 maximum f T area of oscillator operations 0.0 I E = 0 (-0.5mA) -4mA -1.0-1 0 1 2 3 4 V CB [ V ] Technology: SG25H1 (npn200) Stress tests in work T = 125 C, t > 100h 1) high-current : VCB = 0V, IE = 4xIE @ max. f T 2) mixed-mode : VCB = 1.5V, IE = 2x IE @ max. f T 3) high-voltage : VCB = 3V, IE = 0.25x IE @ max. f T
High Current Stress I Base Current, Collector Current [ A ] 10 0 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 t = 0 t = 67h 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 V BE [ V ] 250 200 150 100 Technology: IHP SG25H1 (npn200) Beta Stress conditions T = 125 C, I E = - 20mA, V CB = 0V 50 Stress current density: 37mA/µm² Stress time: 67h Beta degradation 0 @ V BE = 0.7V: 9% @ V BE = 0.8V: 5% @ V BE = 0.9V: 4%
High Current Stress II 200 t = 0 t = 67h 200 Technology: IHP SG25H1 (npn200) 150 150 f T [ GHz ] 100 100 f max [ GHz ] 50 50 Stress conditions T = 125 C, I 0 0 E = - 20mA, V CB = 0V 0.7 0.8 0.9 1.0 1.1 Stress current density: 37 ma/µm² V BE [ V ] Stress time: 67h No RF performance degradation
Mixed-Mode Stress I Base Current, Collector Current [ A ] 10 0 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 t = 0 t = 160h 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 V BE [ V ] 250 200 150 100 Beta Technology: IHP SG25H1 (npn200) Stress conditions 50 T = 125 C, I E = - 10mA, V CB = 1.5V 0 Stress time: 160h Very low Beta degradation!
Mixed-Mode-Stress II 200 150 t = 0 t = 160h 200 150 Technology: IHP SG25H1 (npn200) f T [ GHz ] 100 100 f max [ GHz ] 50 50 0 0 0.7 0.8 0.9 1.0 1.1 V BE [ V ] Stress conditions T = 125 C, I E = - 10mA, V CB = 1.5V Stress time: 160h No RF performance degradation!
High-Voltage Stress I Current [ A ] 10 0 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 T = 125 C, t = 97h T = 27 C, t = 12h 1.0 0.8 0.6 0.4 0.2 0.0 0.4 0.5 0.6 0.7 0.8 V BE [ V ] Beta / Beta (Maximum) Stress conditions J E = - 5.2mA/µm², V CB = 3V Degradation by trap creation in EB spacer region: e - e - h + V C > 3V
High Voltage Stress II Relative Beta Degradation @ V BE = 0.7V 10% 1% 1 10 100 1000 10000 AE = 0.21x0.84 µm² AE = 0.21x1.26 µm² AE = 0.21x1.68 µm² AE = 0.21x3.36 µm² 25% 20% 15% 0.1% 1 10 100 1000 10000 10% Stress Time [ s ] Beta Degradation (t=12h) Stress conditions T = 27 C, J E = - 5.2 ma/µm², V CB = 3V Stress time: 12h 10 11 12 Emitter Perimeter/Area [µm -1 ]
High Voltage Stress III 200 150 t = 0 t = 63h t = 97h 200 150 Technology: IHP SG25H1 (npn200) f T [ GHz ] 100 100 f max [ GHz ] 50 50 0 0 0.7 0.8 0.9 1.0 1.1 V BE [ V ] Stress conditions T = 125 C, I E = - 1.3mA, V CB = 3V Stress time: 97h No RF performance degradation
Resume IHP has portfolio of rf SiGe:C BiCMOS technologies Low-cost technology High-performance technology 0.13 µm technology in development Automotive radar application examples 24 GHz LNA 77/79 GHz VCO Investigation of high temperature sensitivity and reliability necessity for automotive application