APEC '99 Trench-Gate Technology for The Next Generation of MOS Power Devices IEEE, APEC Conference 1999 Eric R. Motto Sr. Application Engineer Powerex Inc. Youngwood PA USA APEC '99 Introduction 1. The Trench Gate Structure, Development History and Advantages 2. Low Voltage MOSFETs RDS(on) DS(on), Small packages, QG, Future Direction 3. High Power IGBT Modules for Industrial Applications Low VCE(sat), Low losses, Reduced EMI/RFI 4. Special Devices Strobe Flash, Fork Lift, Microwave Oven 5. Conclusion APEC '99 Planar versus Trench-Gate MOSFET Unit Cell Comparison Source Source Gate Gate n+ RChannel RJFET p Rn- n- Planar Gate Cell RChannel n- Rnn+ Drain n+ p n+ Drain Trench Gate Cell APEC '99 Advantages of Trench-Gate: l Vertical channel requires less area compared to the horizontal channel of planar structure Ý Greater cell density Ý Greater channel width/unit area Ý Lower RDS(on) l No RJFET between adjacent cells Ý Greater cell density Ý Lower RDS(on) APEC '99 Major Mitsubishi/Powerex Mitsubishi/Powerex TrenchGate Milestones: 1983 - Trench capacitor cell proposed for next generation DRAM 1988 - Mass production of trench capacitor memory launched 1992 - Prototype low voltage trench gate MOSFETs developed 1994 - Mass production of trench gate 30V-150V MOSFETs launched 1994 - Prototype 600V Trench IGBT developed 1994 - 400V Strobe Flash IGBT production started 1995 - 250V 400A, 600A Trench gate IGBT module production started 1998 - 1200V Trench IGBT developed 1999 - Production of 600V, 1200V trench gate IGBT modules started 1999 - Production of sub µm trench MOSFETs started APEC '99 Trench-Gate MOSFET Technology Focus: • • • • • • • Low voltage types 20V - 150V N-channel and P-channel Logic level drive 4V and 2.5V Low RDS(ON) in small packages Low QG Low RDS(ON) at low driving voltage Preserve ESD ruggedness APEC '99 Low voltage MOSFETs benefit most from trench gate: % of RDS(ON) Typical 60V High Density Planar Gate MOSFET Typical 500V MOSFET RCH 30% 10% RJFET 20% 5% RN- 30% 80% Other 20% 5% Trench technology attacks RCH and RJFET APEC '99 Trench-Gate MOSFET Chip Structure : Source Electrode Source Layer P-base Polysilicon Gate Gate Oxide n-epi layer n+ Drain Electrode 5TH Generation stripe trench 1µm design rule Benchmark TO220 (D2-Pak) Devices: RDS(ON) (mΩ Ω) Maximum, VGS=10V, Tj=25C VDSS n-ch, -VDSS p-ch (Volts) 20V 30V 60V 100V 150V n-ch n-ch p-ch n-ch p-ch n-ch p-ch n-ch p-ch 4.0 4.7 12 7.0 19 17 New - FS100VSJ-02A More than 500 types available in TO-220, TO-220 Isolated, D2-Pac, D-pac. Standard and logic level (4V, 2.5V) drive. n-channel and p-channel 50 30 100 APEC '99 Reducing QG: For DC to DC converter and synchronous rectification applications: Package Type SOP-8 FY10AAJ-03 VDSS 30V Qg Max RDS(on) Ciss 2850pF 32nC 13.5mΩ SOP-8 30V 13.5mΩ Process Conventional Trench FY10AAJ-03A Shallow Trench 1800pF 22nC DC to DC Converter Efficiency V IN=15V, VOUT=3.3V, f=300kHz 93 Efficiency (%) FY10AAJ-03A 91 FY10AAJ-03 89 1 2 3 4 Output Current (Amps) 30% Reduction of Gate Charge APEC '99 Low RDS(ON) DS(ON) in small package: SOP-8 Package Type TSSOP-8 Process FY7ACH-03A 5th Generation Dual n-channel Shallow Trench TSSOP-8 FY7BCH-02A 5th Generation Dual n-channel Mesh Trench SOP-8 VDSS 30V Max RDS(on) 26mΩ 20V 25mΩ Ω APEC '99 Low RDS(ON) DS(ON) at low drive voltage: - Package Configuration Type Number Max RDS(ON) VGS=4.0V SOP-8 Single n-channel FY10AAJ-03A 20mΩ 20mΩ SOP-8 Single p-channel FY8ABJ-03 37mΩ 37mΩ VGS=2.5V SOP-8 Dual n-channel FY8ACH-02A 36mΩ 36mΩ TSSOP-8 Dual n-channel FY7BCH-02A 37mΩ 37mΩ Don’t be fooled - Industry standard is to supply maximum RDS(ON) at VGS=10V for logic level (4V drive) devices and VGS=4V for 2.5V drive devices Powerex/Mistubishi Powerex/Mistubishi provides maximum RDS(ON) DS(ON) specified at low drive voltage for all logic level (4V, 2.5V) devices APEC '99 Preserving ESD ruggedness: Two methods to reduce RDS(ON) DS(ON) at low drive voltages (1) Increase channel width/unit chip area - Trench gate structure is very effective for this approach (2) Reduce gate oxide thickness - This approach degrades VGSS and ESD ruggedness ESD W ithstanding (Human Body Model) FY10AAJ-03A (No failures) 4000V 3000V Test Voltage 2000V Competitive Device 1000V 10 20 30 Samples 40 APEC '99 More ESD ruggedness: Adopt an integrated gate protection zener Package Type Process FY6BCH-02E 5th Generation Dual n-channel Mesh Trench With integrated G-S zener TSSOP-8 FY7BCH-02E 5th Generation Dual n-channel Mesh Trench With integrated G-S zener TSSOP-8 VDSS 20V Max RDS(on) 30mΩ Ω 20V 27mΩ Ω APEC '99 Trench-gate MOSFET future direction: Next Step - Sub µm design trench Under Development Package TSSOP-8 Type FY7BCH-02B Dual n-channel FY8BCH-02 TSSOP-8 Dual n-channel Process VDSS Proprietary 20V Max RDS(on) 21mΩ Ω Proprietary 20V 19mΩ Ω More types under development…. APEC '99 Trench-Gate IGBT Modules (For High Power Industrial Applications) Technology Focus: • Low VCE(sat) , Low Losses • Full Line-Up 600V and 1200V 50A-600A • High Reliability • Reduced EMI/RFI Advantages of Trench-Gate Structure for IGBT: l Vertical channel requires less area compared to the horizontal channel of planar structure Ý Greater cell density Ý More uniform current flow through chip Ý Robust Turn-Off Switching Capability l No RJFET between adjacent cells Ý Greater cell density Ý Lower VCE(SAT) APEC '99 Reducing VCE(sat) CE(sat): Emitter Emitter Gate Gate n+ RChannel RJFET p Rn- n- Planar Gate IGBT IGBT Cell RChannel n- Rnn+ p+ Collector n+ p n+ p+ Region of local lifetime control Collector New Trench Gate IGBT Cell Components Reduction Technique of VCE(sat) Adopt trench gate surface structure to increase cell RChannel RJFET Rn- density and channel width per unit area Eliminate by adopting trench gate structure Utilize optimized PT chip design with local lifetime control to increase on-state carrier concentration APEC '99 IGBT Structure Comparison: PT IGBT Poly-Si Gate NPT IGBT Emitter Electrode n- drift region Poly-Si Gate n- drift region n+ buffer layer p+ anode Collector Electrode APEC '99 Advantages of PT structure: l n- layer thickness and resistivity can be optimized for low VCE(sat) without special thin wafer processing or leakage current stability problems. l Low VCE(sat) at elevated junction temperature l Tail current time is short (due to lifetime control) (~0.3µs versus several µs for NPT) l Low leakage current at high temperatures (one tenth to one twentieth of thin n- NPT) APEC '99 Effect of Local Lifetime Control Using Heavy Ion Irradiation: • Carrier lifetime in the n+ buffer layer is reduced • • • using local life time control Long lifetime is maintained in the n- layer Carrier concentration in the n- layer during conduction is increased Rn- is reduced í VCE(sat) is Reduced APEC '99 Maintaining Short Circuit Withstanding: Adopt RTC (Real Time Control Circuit) to clamp short circuit current Trench Gate IGBT C Main Emitter Area G RTC Circuit E Current Mirror Emitter Gate APEC '99 1200V Trench Gate IGBT Performance: ESW(off) versus VCE(sat) Trade-Off 4.0 Old NPT 3.5 New NPT 3.0 V CE(sat) (V) Tj=125C IC =100A Powerex U-Series 2.5 Powerex H-Series 2.0 New TrenchGate IGBT 1.5 1.0 0 5 10 15 20 25 E S W (off) (mJ/pulse) Tj=125C, IC =100A, V CC =600V 30 APEC '99 Characteristics of 1200V (F-Series) trench gate IGBT: Parameter Conditions 3rd Gen. Planar Trench VCE(sat) Tj=125C 2.85V SWSOA 2X IC(rated) Square Square tSC Short Circuit Withstand Time >10µs >10µs ESW(off) Turn-Off Switching Energy (Normalized) 1.0 1.9V 0.8 APEC '99 Characteristics of 600V (F-Series) trench gate IGBT: Parameter Conditions 3rd Gen. Planar Trench VCE(sat) Tj=125C 2.6V 1.6V SWSOA 2X IC(rated) Current Density Square Square tSC Short Circuit Withstand Time >10µs >10µs ESW(off) Turn-Off Switching Energy (Normalized) 1.0 0.75 APEC '99 Next Generation Performance: 1200V F-Series IGBT Module Parameter VCE(sat) (V) Tj=125C Switching Loss - Eon+EOFF Total Sinusoidal Output Inverter Loss fPWM=10KHz Thermal Impedance RTH(j-c) Temperature Rise - TJ-C Third Generation H-Series 2.3 1.0 1.0 Trench Gate 1.0 1.0 1.45 1.0 30% Reduction of losses ! 1.9 0.85 0.70 APEC '99 Evolution of Industrial Power Semiconductor Modules: Chip Technology Darlington Transistor High-β G1 IGBT G2 IGBT Package Technology Generation 3 IGBT Conventional Al2O3 Trench Al2O3 DBC AlN DBC (Soldered Power Terminals) U-Package APEC '99 New Module Package Main Terminal Electrode Silicone Gel Epoxy Resin Molded Case Conventional Module (H-Series) Solder Connection Cu Base Plate Main Terminal Electrode Silicone Gel Power Chips AlN Substrate Cover Insert Molded Case New Module (U-Package) Al Bond Wires Cu Base Plate Power Chips AlN Substrate APEC '99 Advantages of the New Module Package: Low Inductance - Insert molded case allows low inductance electrode designs Low Capacitance - Substrate geometry optimized for reduced leakage capacitance to the base plate Improved Reliability - Solder joints between power electrodes and base plate have been eliminated. Low temperature solder used to attach chips and substrate. Improved Manufacturability - Soldering passes reduced from 2 to 1 Increased Resistance to Bending Stresses - Smaller ceramic substrates and thicker copper base minimize breakage and allow greater mounting torque APEC '99 New Module Package: Dual 300A, 1200V Trench-Gate IGBT Module (CM300DU-24F) APEC '99 Worlds Most Powerful SOP-8 CY25AAJ-8 400V, 150A Strobe Flash IGBT Charging Circuit Designed for compact digital cameras 400uF 350VDC Xenon Tube Features: Trench gate technology 4V gate drive High current/small package VTRIG VG=4V APEC '99 '98 Low VCE(SAT) CE(SAT) 250V IGBT Modules For forklift and light electric vehicles Features: • Low VCE(SAT)= 1.1V (Tj=125C, IC=IC(RATED)) • High Reliability Packaging • Robust Switching SOA Type CM600HA-5F CM450HA-5F CM350DU-5F CM200TU-5F Circuit Single Single Dual Six-Pack New Product Current 600A 450A 350A 200A APEC '99 Trench IGBT for Resonant Operation For Microwave Oven/Induction Heating CT60AM-18B Features: • Low V = 2.0V (Tj=125C, IC=IC(RATED)) CE(SAT) • Low tail loss • Integrated anti-parallel diode • TO-3PL (TO264) Outline APEC '99 Conclusion Trench-Gate technology is effective for improving the key characteristics of a wide range of power semiconductor devices. Examples presented: • Low voltage MOSFETs (especially small package types) • Industrial IGBT modules (600V and 1200V) • Special Devices (strobe flash, forklift, resonant mode)