Present Present Status Status And And Future Future Prospects of of SiC SiC Power Power Devices 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 Present Status Status And And Future Future Prospects of of SiC SiC Power Power Devices Devices Introduction Device Achievements & Needs Future Prospects of SiC Power Devices Conclusion
Evolution of of Power Devices 1950 1970 1980 1990 2000 First Wave (Uncontrollable Latching Devices) Triac Thyristor RC Thyristor Light Trig. Thyristor Second Wave (Controllable Non-Latching Devices) Third Wave (MOS-Gate Controlled Devices & Power ICs) Bipolar Transistor SIT Bipolar Tr. Module 1991 : Second Generation MOSFET & IGBT Power MOSFET (5μm design rule). 1993 : Third Generation MOSFET & IGBT IGBT (3μm design rule). 1995 : Fourth Generation MOSFET (1.5μm design rule). 1995 : Fourth Generation IGBT (1μm design rule; Trench Version). 1997 : Fifth Generation MOSFET (1μm design rule). 1999 : Fourth Generation IGBT (1μm design rule; Planar 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. GTO GCT High β Bip. Tr. Module Power MOS. Module IGBT Module IPM; ASIPM *Note ; DIP-IPM; HEV-IPM; HVIPM; Power ICs Trench MOS Sub µm MOS Trench IGBT IPM Introduction by Mitsubishi Sub µm IGBT CSTBTTM *Note System Integrated Solutions New Devices (SiC Devices)
Reduction of IGBT operation losses 1985 1990 1995 2000 2005 1 st Gen 2 nd Gen. E series 3 rd Gen. H series 4 th Gen. F series 5 th Gen. NF series Device using new material Power Loss (W) 100W IGBT turn-off loss IGBT conduction loss Overall power loss reduced to 1/3 75W Power losses in inverter application 50W 40W 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 33W CSTBT TM IGBT turn-on loss 1 st Gen. 2 nd Gen. 3 rd Gen. 4 th Gen. 5 th Gen. Planar gate Trench gate
Static characteristics of Si & SiC devices compared with theoretical limits Relationship between specific on-resistance and breakdown voltage 1000 Specific Ron (mohm-cm2) 100 10 1 0.1 Power MOSFET Silicon Unipolar Limit IGBT-2G CSTBT TM Super Junction Unipolar Limit (Estimated for J p =1μm) Super Junction MOSFET IGBT-3G HV-Thyristor/GTO family HV-IGBT Estimated PiN Diode Limit (Bipolar) 4H-SiC Unipolar Limit Compared at Tj or Tch = 400K 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 Density Enhancement for for Medium Power PE PE Equipment Power パワー密度 Density [W/cc] (w/cc) 100 10 1 Gen-purpose Inverter ( Bipolar ) 0.1 Gen-purpose Inverter ( IPM ) Gen-purpose Inverter ( DIP-IPM ) M-Converter (RB-IGBT) 0.01 1980 1990 2000 2010 2020 年 Year M-Converter Inverter HEV Inverter Gen-purpose Inverter ( RC-IGBT & others ) HEV Inverter ( EV-IPM ) 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 Efforts toward SiC Application Integration Technology New Packaging Technologies
Comparison of Device Structure and Distribution of Electric Field source p ~ n + Si gate n - n- Si drift layer (very low carrier concentration) Si substrate drain Breakdown Electric Field x 10 source source n + p ~ Si SiC Distribution of electric field E p ~ SiC gate n + n n - + p n-sic drift layer SiC substrate ~ drain drift layer thickness: very thin carrier concentration: very high = Drastic reduction of On-state Loss source
Merits of SiC Devices Ideal SiC devices for power applications Critical Electrical Breakdown Field [MV/cm] 6 5 4 3 2 1 SiC Poly types 4H-SiC 3C-SiC 6H-SiC Wide bandgap High critical BV Si Diamond 1.89A 2.35A On-state voltage [V] 10 1 Si-MOSFET 0.1 Si-GTO Si-IGBT 1 10 Breakdown voltage [kv] Low loss, high voltage SiC devices SiC-IGBT SiC-MOSFET 0 1 2 3 4 Bandgap [ev] 5 6
Material Bandgap Energy Physical parameters of of different materials and expectations from SiC Dielectric Constant Electron Mobility Breakdown Electric Field Saturated Electron Drift Velocity Thermal Conductivity E g ε r μ n Ε c ν sat λ ev (dimension) cm 2 /Vs 10 6 V/cm 10 7 cm/s W/cm.K Si 1.1 11.9 1500 0.3 1.0 1.5 GaN 3.4 9.5 900 2.6 2.5 1.3 3C-SiC 2.2 9.7 800 3.0 2.7 4.9 4H-SiC 3.0 9.7 1000 3.5 2.7 4.9 6H-SiC 2.9 9.7 460 3.0 2.0 4.9 Low On-resistance 4H-SiC : Silicon (approx. 1/100 of Si) High temp. operation (approx. 3x of Si) 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) Higher voltage > 10kV Higher current density DC transmission Steel mill traction Automotive Inverter UPS Operation frequency (Hz) Voltage driven device (MOSgated) Higher voltage, higher current On-state resistive loss reduction MOSFET-like fast switching speed Simple forced air cooling realized by higher Tj operation FOM λ*johnson FOM λ*(e c * ע sat ) 2 1 407 2381 3241 1307 MOSFET-like fast speed Lower power loss Higher junction temperature
Silicon Carbide R & D status Specific on-resistance (mωcm 2 ) 100 10 Si-limit 1/10 of Si-limit1/100 of Si-limit Mitsubishi (2002) Mitsubishi (2002) SiC-limit SiC 4H 6H MOSFET Schottky (2002) epi-layer channel source n-drift layer drain gate p-body contact Al-implanted p-body n-sic substrate High Temp Epitaxial Growth Previous work 4H-SiC (2002) Double Implanted OSFET VBr=1900V R on =40mΩcm 2 1. High voltage vertical structure 2. Double implantation 3. Epilayer channel -High quality -Doping control 4. JTE termination 4H-SiC Previous work (2002) Schottky Barrier Diode VBr=1500V R on =3mΩcm 2 1 500 1000 2000 Breakdown voltage 5000 (V)
Drain current (ma) Electrical characteristics of initial 4H-SiC Power MOSFET test element R on =40mΩcm 2 20 V g =20V V g =25V ドレイン電流 (ma) -2 1x10-3 8x10-3 6x10 10-3 V 4x10 g =15V -3 V b =1900V 2x10 V g =10V V g =0V 0 0 0 1 V g =0.5V 2 0 1000 2000 Drain-Source Voltage (V) Initial work (2002) Ron = 40mOhm.cm 2 BV = 1900V Drain-Source Voltage (V)
100 Silicon Carbide R & D goals Si-limit 1/10 of Si-limit 1/100 of Si-limit Mitsubishi 2001 Specific on-resistance (mωcm 2 ) 10 Mitsubishi Mitsubishi 2002 SiC-limit MOSFET Schottky mobility=20cm 2 /Vs channel length=3µm mobility=100cm 2 /Vs channel length=3µm mobility=100cm 2 /Vs channel length=1µm 1 500 1000 2000 5000 Breakdown voltage (V)
Silicon Carbide R & D goals New SiC High Voltage MOSFET Development p++ n+ p+ Source Metal Poly Si Gate Epitaxial Channel Channel Area n- Epitaxial Layer Contact Hole n+ p+ Source Area Present target (2004) p++ Gate Pad Al source electrodes n+ SiC Substrate Drain Metal 1mm 25μm Gate length: 2μm SiC MOSFET Cell Structure 4H-SiC High Voltage MOSFET (Experimental chip) (Performance :1200V, 13mΩ cm 2 )
Performance of a 30A/600V 4HSiC-SBD chip (experimental)
SiC SiC application application example example (Future) (Future) High performance PFC-Inverter for Air-conditioning PFC Circuit (High frequency, Low loss requirement) P DC 300-400V (controllable) P Inverter Circuit DIP-IPM Relay ACL R N/F S LVIC Co Co Co M AC 90-264V (universal) Q2 Q1 N N N2 HVIC HVIC HVIC LVIC Preferable device: SiC-SBD SBD Compact Compact PFC-Inverter PFC-Inverter system system Complete Complete clear clear of of harmonic harmonic current regulation current regulation High performance PAM control High performance PAM control High system efficiency High system efficiency Possible module packaging Control IC DIP-PFC Use of DIP-IPM concept DIP-IPM MCU
Inverter Operation Loss [Ratio] 1.20 1.00 0.80 0.60 0.40 0.20 0.00 - Predicted system benefits - Si-CSTBT+Si-FWDi Device active area : 1 - based on simulation using 1200V device designs - 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 Conditions for Simulation: 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: 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. 0.16 0.25 0.50 SiC-MOSFET+SiC-SBD Device active area System Cost Reduction
Adoption of high frequency control Inverter Operation Loss [Ratio] 1.20 1.00 0.80 0.60 0.40 0.20 0.00 - Predicted system benefits - - based on simulation using 1200V device designs - Reduces size/weight of peripheral components Si-CSTBT+Si-FWDi (limited to roughly 20kHz) Device active area : 1 System Cost Reduction 75 100 125 150 175 200 225 250 275 Junction Temp. [ ] Conditions for Simulation: 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 at Tj=125 /fc=20khz operation is referenced as unity for comparison. 2) Assumed values for simulation purpose. 100kHz 50kHz 20kHz SiC-MOSFET+SiC-SBD Device active area :0.25
- Predicted system benefits - Si vs. SiC comparison for 460V/22kW/3-ph MC Si-IGBT Module (5 th Gen. Dual 100A/1200V) Operating Tj = 125 deg. C Volume ratio = 1/3 Power-loss ratio = 0.4 SiC-MOSFET Module (Dual 100A/1200V) Operating Tj = 250 deg. C Cooling fans Forced air-cooling Natural air-cooling 3-ph inverter using silicon (state-of-the-art) 3-ph inverter using SiC (Future prediction)
Predicted Major Applications of of 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 key key issues and and projections (1) Pipe density reduction (2) Wafer diameter increment Wafer Diameter(inch) 6 5 Diameter A Diameter B Diameter C 4 Pipe density (MPD) for A 3 10 2 5 1 0 1995 1997 1999 2001 2003 2005 2007 2009 2011 Year 30 25 20 15 MPD (cm -2 ) (Data from ICSCRM 2001)
Scenario for application of of SiC devices High cost Cost issue Higher reliability, Simpler system design, Safer Operation Normally Off type preferred Lower cost Home Appliances <600V Higher power, Higher voltage Motor Drives for Industry 600V-1200V Uninterruptible Power Supplies (UPS) 600V-1200V Power Transmission > 5000V Traction, Large Motor Drives >1700V Automotive (EV,HEV,FCV) 600V-1000V Adequate performance in harsh application surroundings High voltage High power V-I rating issue Low cost Reliability issue High grade Low voltage Low power
Power Device Development Roadmap Functions / Performance Key Power Devices Key Power Devices LPT-CSTBT MPS-Diode Sub-micron MOSFET Process Refine Key Power Devices Reverse Conducting IGBT Reverse Blocking IGBT Intelligent devices Key Processes Versatility Sub-micron Cell-Trench Structure Thin wafer Key Power Devices SiC-FET, SiC-SBD, Intelligent devices Key Processes Key Processes SiC wafer process Hi-speed epitaxial growth Hi-grade oxide formation ) New Material Deep-Trench Structure Ultra-thin wafer Backside diffusion Multi-layered connections 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 2002 2003 2004 2005 2006 2007 2008 (FY)
and