Present PresentStatus StatusAnd AndFuture FutureProspects Prospectsof ofSiC SiCPower PowerDevices Devices Contributors : Gourab Majumdar Chief Engineer, Power Device Works, Mitsubishi Electric Corporation, Japan John Donlon Senior Application Engineer, Powerex Inc., U.S.A. Eric Motto Principal Application Engineer, Powerex Inc., U.S.A. Tatsuo Ozeki Project Manager, SiC Project Group, Advanced Technology R & D Center, Mitsubishi Electric Corporation, Japan Hidekazu Yamamoto Manager, Power Device Development Dept., Power Device Works, Mitsubishi Electric Corporation, Japan Makoto Seto Manager, Power Electronics System Development Center, Advanced Technology R & D Center, Mitsubishi Electric Corporation, Japan Abstract: At Mitsubishi, R & D work on SiC Power Devices has been continuing for several years through implementation of in-house strategic projects and by active participation in national projects in Japan. Through these activities, advanced high performance MOSFET and Schottky Barrier Diode devices of 1200V-2000V class have been developed. In this presentation, the technical results of these activities will be briefly explained. The conceptual aspects and performance-related evaluation results of some experimental SiC-MOSFET and SiC-SBD device structures will be shown. It will conclude with some discussion of existing issues and possibilities concerning SiC power devices becoming the future de facto solution in the industry. Present PresentStatus StatusAnd AndFuture FutureProspects Prospectsof ofSiC SiCPower PowerDevices Devices Introduction Device Achievements & Needs Future Prospects of SiC Power Devices Conclusion Evolution Evolution of of Power Power Devices Devices 1950 1970 First Wave (Uncontrollable Latching Devices) Triac Thyristor 1980 1990 RC Thyristor Light Trig. Thyristor Second Wave (Controllable Non-Latching Devices) GTO Bipolar Transistor SIT Bipolar Tr. Module 1991 1991 :: Second Second Generation Generation MOSFET MOSFET & & IGBT IGBTPower MOSFET (5μm (5μm design design rule). rule). Third Wave (MOS-Gate Controlled Devices & Power ICs) 2000 1993 1993 :: Third Third Generation Generation MOSFET MOSFET & & IGBT IGBT (3μm (3μm design design rule). rule). GCT High β Bip. Tr. Module Power MOS. Module Trench MOS Sub µm MOS IGBT 1995 1995 :: Fourth Fourth Generation Generation MOSFET MOSFET IGBT Module (1.5μm (1.5μm design design rule). rule). 1995 1995 :: Fourth Fourth Generation Generation IGBT IGBT (1μm (1μm design design rule; rule; Trench Trench Version). Version). 1997 1997 :: Fifth Fifth Generation Generation MOSFET MOSFET (1μm (1μm design design rule). rule). 1999 1999 :: Fourth Fourth Generation Generation IGBT IGBT (1μm (1μm design design rule; rule; Planar Planar Version). Version). *Note: ASIPM ≡ Mitsubishi’s Application Specific Intelligent Power Module. TM CSTBT ≡ Mitsubishi’s Carrier stored trench gated bipolar transistor. “..Generation” ≡ The denominations refer to Mitsubishi’ s technologies. Trench IGBT Sub µm IGBT CSTBTTM *Note IPM; ASIPM *Note; System DIP-IPM; Integrated HEV-IPM; Solutions HVIPM; Power ICs New Devices (SiC Devices) IPM Introduction by Mitsubishi Reduction of IGBT operation losses 1985 1st Gen Power Loss (W) 100W IGBT turn-off loss 1990 2nd Gen. E series Ov er a ll p o 75W 1995 3rd Gen. H series 2000 4th Gen. F series 5th Gen. NF series Power losses in inverter application we r lo ss IGBT conduction loss re d uce d 50W to 1 40W 2nd Gen. Planar gate 3rd Gen. 4th Gen. Device using new material Simulated Conditions Device Ratings = 75A, 600V Application : VVVF Inverter Circuit Inverter Output Current,Io = 45Ar.m.s. Control Scheme = PWM, Sinusoidal Carrier frequency,fc = 15kHz Power factor, φ = 0.8 /3 33W CSTBTTM IGBT turn-on loss 1st Gen. 2005 5th Gen. Trench gate Static characteristics of Si & SiC devices compared with theoretical limits Relationship between specific on-resistance and breakdown voltage Specific Ron (mohm-cm2) 1000 Silicon Unipolar Limit HV-Thyristor/GTO family Super Junction MOSFET HV-IGBT IGBT-2G 100 IGBT-3G Power MOSFET 10 CSTBTTM Estimated PiN Diode Limit (Bipolar) 1 Super Junction Unipolar Limit 4H-SiC Unipolar Limit (Estimated for Jp=1μm） Compared at Tj or Tch = 400K 0.1 10 100 1000 10000 Breakdown Voltage (V) In terms of power losses, the users have benefited from continuous improvement made by various generations of IGBT families over the past 20 years Power PowerDensity DensityEnhancement Enhancementfor forMedium MediumPower PowerPE PEEquipment Equipment Power Density (w/cc) パワー密度 [W/cc] 100 M-Converter Inverter • Efforts toward HEV Inverter SiC Application • Integration M-Converter Technology （RB-IGBT) • New Packaging Technologies Gen-purpose Inverter 10 ( DIP-IPM ) 1 Note: IPM: Intelligent Power Module DIP-IPM: Dual In-line Package IPM EV-IPM: IPM for EV and/or HEV applications RB-IGBT: Reverse Blocking type IGBT RC-IGBT: Reverse Conducting type IGBT M-Converter: Matrix Converter HEV Inverter: Inverter systems for hybrid vehicles 0 .1 0 .0 1 1980 HEV Inverter ( EV-IPM ) Gen-purpose Inverter ( IPM ) Gen-purpose Inverter ( Bipolar ) Gen-purpose Inverter ( RC-IGBT & others ) 1990 2000 年 Year 2010 2020 Comparison Comparison of of Device Device Structure Structure and and Distribution Distribution of of Electric Electric Field Field SiC Si source Breakdown Electric Field x 10 source source gate + p n n+ p E n- SiC Distribution of electric field n- Si drift layer (very low carrier concentration) ～ ～ Si substrate drain Si ～ ～ gate + p n n- source n+ p n-SiC drift layer ～ ～ SiC substrate drain drift layer thickness: very thin carrier concentration: very high = Drastic reduction of On-state Loss ～ ～ Merits of SiC Devices 6 Diamond 5 1.89Å SiC Poly types 4 3 4H-SiC 3C-SiC 6H-SiC On-state voltage [V] Critical Electrical Breakdown Field [MV/cm] Ideal SiC devices for power applications 10 Si-GTO Si-IGBT SiC-IGBT 1 Si-MOSFET SiC-MOSFET 0.1 1 10 Breakdown voltage [kV] 2 Low loss, high voltage SiC devices Wide bandgap High critical BV 1 2.35Å Si 0 1 2 3 4 Bandgap [eV] 5 6 Physical Physicalparameters parametersof ofdifferent differentmaterials materials and andexpectations expectationsfrom fromSiC SiC Material Saturated Breakdown Thermal FOM Electron Drift Electric Field Conductivity 【λ＊Johnson FOM】 Velocity Bandgap Energy Dielectric Constant Electron Mobility Eg εr μn (dimension) 2 cm /Vｓ 10 Ｖ/cm 10 cm/s W/cm.K 11.9 9.5 9.7 9.7 9.7 1500 900 800 1000 460 0.3 2.6 3.0 3.5 3.0 1.0 2.5 2.7 2.7 2.0 1.5 1.3 4.9 4.9 4.9 eV 1.1 3.4 2.2 3.0 2.9 4H-SiC : Silicon Si GaN 3C-SiC 4H-SiC 6H-SiC Low On-resistance (approx. 1/100 of Si） Εc νsat 6 λ 7 【 λ＊（Ec＊ עsat）2 】 1 407 2381 3241 1307 • Higher voltage > 10kV • Higher current density High Breakdown Voltage (approx. 10x of Si) High Thermal Conductivity (approx. 10x of Si) System Merits Loss reduction Down sizing Cost reduction Capacity of applied system (VA) High temp. operation (approx. 3x of Si) • Voltage driven device (MOSgated) • Higher voltage, higher current • On-state resistive loss reduction DC transmission Steel mill traction • MOSFET-like fast switching speed • Simple forced air cooling realized by higher Tj operation Automotive Inverter UPS Operation frequency (Hz) • MOSFET-like fast speed • Lower power loss • Higher junction temperature Silicon Silicon Carbide Carbide RR && DD status status epi-layer channel Specific on-resistance (mΩcm2) 100 Si-limit 1/10 of Si-limit1/100 of Si-limit source gate p-body contact Al-implanted p-body Mitsubishi (2002) n-drift layer n-SiC substrate drain Previous work 4H-SiC(2002) Double Implanted OSFET VBr=1900V Ron=40mΩcm2 1. High voltage vertical structure 2. Double implantation 3. Epilayer channel -High quality -Doping control 4. JTE termination 10 SiC 4H 6H MOSFET Schottky Mitsubishi (2002) SiC-limit 1 500 1000 2000 5000 Breakdown voltage (V) High Temp Epitaxial Growth Previous work (2002) 4H-SiC Schottky Barrier Diode VBr=1500V Ron=3mΩcm2 Electrical characteristics of initial 4H-SiC Power MOSFET test element Initial work (2002) Ron=40mΩcm2 ドレイン電流 (mA) 20 Drain current (mA) Vg=20V Vg=25V 10 1x10 -2 -3 8x10 -3 6x10 -3 Vg=15V 4x10 Vb=1900V -3 2x10 Vg=10V 0 0 1 Vg=0.5V 2 Drain-Source Voltage (V) Vg=0V 0 0 1000 2000 Drain-Source Voltage (V) Ron = 40mOhm.cm2 BV = 1900V Silicon SiliconCarbide CarbideRR& &DDgoals goals Si-limit Specific on-resistance (mΩcm2) 100 1/10 of Si-limit 1/100 of Si-limit Mitsubishi 2001 mobility=20cm2/Vs channel length=3µm Mitsubishi 2002 mobility=100cm2/Vs channel length=3µm mobility=100cm2/Vs channel length=1µm 10 Mitsubishi SiC-limit MOSFET Schottky 1 500 1000 2000 5000 Breakdown voltage (V) Silicon SiliconCarbide CarbideRR& &DDgoals goals New SiC High Voltage MOSFET Development Present target (2004) Gate Pad Source Metal Contact Hole Poly Si Gate Epitaxial Channel p++ n+ p+ n+ p+ Channel Area p++ Source Area n- Epitaxial Layer n+ SiC Substrate Al source electrodes １mm Drain Metal ２５μm Gate length: 2μm SiC MOSFET Cell Structure 4H-SiC High Voltage MOSFET (Experimental chip) (Performance :1200V, 13mΩ・cm2) Performance of a 30A/600V 4HSiC-SBD chip (experimental) SiC SiCapplication applicationexample example(Future) (Future) High performance PFC-Inverter for Air-conditioning PFC Circuit (High frequency, Low loss requirement) P Inverter Circuit DC 300-400V (controllable) P DIP-IPM Relay N/F R LVIC ACL S Q2 Co’ Co M Q1 AC 90-264V N (universal) N2 Preferable device: SiC-SBD N HVIC HVIC HVIC Control Possible module packaging ●CompactPFC-Inverter PFC-Invertersystem system ●Compact ●Completeclear clearofofharmonic harmonic ●Complete currentregulation regulation current ● High performance PAMcontrol control ● High performance PAM Highsystem systemefficiency efficiency ●●High Co’’ MCU IC DIP-PFC Use of DIP-IPM concept DIP-IPM LVIC - Predicted system benefits - based on simulation using 1200V device designs Conditions for Simulation: Inverter Operation Loss ［Ratio］ 1.20 Vcc=600V, Irms=31A, Modulation ratio=1.0 Power Factor=0.8, fc=20kHz (Sinusoidal PWM) SiC-MOSFET Ron=5mΩcm2@25℃ (Note-2) SiC-SBD Ron=3mΩcm2@25℃ (Note-2) Note: Si-CSTBT＋Si-FWDi Device active area : 1 1.00 1) Exsisting Silicon-IGBT based system's device loss at Tj=125℃/fc=20kHz operation is referenced as unity for comparison. 2) Assumed values for simulation purpose. 0.80 0.60 0.16 0.40 0.25 0.50 0.20 SiC-MOSFET＋SiC-SBD Device active area 0.00 75 100 125 150 175 200 225 250 275 Junction Temp. [℃] High temp. operation will allow chip size reduction and attribute to lower power losses, simultaneously. • Higher power density • Simpler hardware for thermal management System Cost Reduction - Predicted system benefits - based on simulation using 1200V device designs Adoption of high frequency control 1.20 Reduces size/weight of peripheral components Si-CSTBT＋Si-FWDi Inverter Operation Loss ［Ratio］ 1.00 Vcc=600V, Irms=31A, Modulation ratio=1.0 Power Factor=0.8, fc=Vriable (20-100kHz) SiC-MOSFET Ron=5mΩcm2@25℃ (Note-2) SiC-SBD Ron=3mΩcm2@25℃ (Note-2) SiC device active area = 25% of Si-IGBT device active area Note: 1)Existing Silicon-IGBT based system's device loss (limited to roughly 20kHz) Device active area : 1 Conditions for Simulation: System Cost Reduction at Tj=125℃/fc=20kHz operation is referenced as unity for comparison. 2) Assumed values for simulation purpose. 100ｋHz 0.80 0.60 50ｋHz 0.40 20ｋHz 0.20 SiC-MOSFET＋SiC-SBD Device active area ：0.25 0.00 75 100 125 150 175 200 Junction Temp. [℃] 225 250 275 - Predicted system benefits Si vs. SiC comparison for 460V/22kW/3-ph MC (5th Si-IGBT Module Gen. Dual 100A/1200V) Volume ratio = 1/3 Power-loss ratio = 0.4 SiC-MOSFET Module (Dual 100A/1200V) Operating Tj = 125 deg. C Operating Tj = 250 deg. C Cooling fans Forced air-cooling Natural air-cooling 3-ph inverter using silicon 3-ph inverter using SiC (state-of-the-art) (Future prediction) Predicted PredictedMajor MajorApplications Applicationsof ofSiC-MOSFET SiC-MOSFET Motor Controls and Power Supplies Applications Home Appliances （refrigerator, air-conditioner, and washing machines） Automotive (EV, HEV, and FCV) Elevators, UPS and Factory Automation, Power supplies, Alternative energy sources Electric Railway Systems, Metal Industries Power network, Utilities Voltage Ratings 600 V 600-1200 V 600-1700 V 1200-6500 V > 10kV The Thekey keyissues issuesand andprojections projections 30 25 6 5 4 Diameter A Diameter B 20 Diameter C 15 Pipe density (MPD) for A 3 10 2 5 1 1995 1997 1999 2001 2003 2005 2007 2009 2011 MPD (cm-2) Wafer Diameter(inch） (1) Pipe density reduction (2) Wafer diameter increment 0 Year (Data from ICSCRM 2001) Scenario Scenario for for application application of of SiC SiC devices devices Higher reliability, Simpler system design, Safer Operation High cost Cost issue Normally Off type preferred Higher power, Higher voltage > 5000V Traction, Large Motor Drives >1700V Motor Drives for Industry Lower cost Home Appliances <600V 600V-1200V Automotive (EV,HEV,FCV) 600V-1000V Uninterruptible Power Supplies (UPS) Adequate performance in harsh application surroundings High voltage High power V-I rating issue Power Transmission 600V-1200V Low voltage Low power Low cost Reliability issue High grade Power PowerDevice DeviceDevelopment DevelopmentRoadmap Roadmap Functions / Performance Key Power Devices SiC-FET, SiC-SBD, Intelligent devices Key Power Devices Reverse Conducting IGBT Reverse Blocking IGBT Intelligent devices Key Power Devices al i r te a MKey Processes w Ne SiC wafer process Hi-speed epitaxial growth Hi-grade oxide formation ) it y l i t a Key Processes s r Deep-Trench Structure Ve LPT-CSTBT MPS-Diode Sub-micron MOSFET Ultra-thin wafer Backside diffusion Multi-layered connections e n i f e R s Key Processes s e c Sub-micron Cell-Trench Structure o r P Denominations : LPT-CSTBT: Light Punch-through CSTBT MPS-Diode : Merged PiN Schottky Diode SiC-FET : Silicon Carbide FET SiC-SBD : Silicon Carbide Schottky Barrier Diode Thin wafer 2002 2003 2004 2005 2006 2007 2008 (FY) and