Power Semiconductors for Power Electronics Applications Munaf Rahimo, Corporate Executive Engineer Grid Systems R&D, Power Systems ABB Switzerland Ltd, Semiconductors CAS-PSI Special course Power Converters, Baden th Switzerland, 8 May 2014 © ABB Group May 16, 2014 | Slide 1 Contents § Power Electronics and Power Semiconductors § Understanding the Basics § Technologies and Performance § Packaging Concepts § Technology Drivers and Trends § Wide Band gap Technologies § Conclusions © ABB Group May 16, 2014 | Slide 2 Power Electronics and Power Semiconductors FWD1 S1 S3 S5 VDC S2 S4 S6 © ABB Group May 16, 2014 | Slide 3 Power Electronics Applications are …. .. an established technology that bridges the power industry with its needs for flexible and fast controllers DC Transportation AC AC = = M Grid Systems ~ ~ 104 HVDC Traction FACTS 103 Power Motor Industrial Drives Supply Drive 102 Device Current [A] HP 101 Automotive DC → AC Lighting AC → DC AC(V , , ) AC(V , , ) 100 1 ω1 ϕ1 → 2 ω2 ϕ2 DC(V1) → DC(V2) 1 2 3 4 10 10 10 10 PE conversion employ controllable solid-state switches referred to as Power Semiconductors Device Blocking Voltage [V] © ABB Group May 16, 2014 | Slide 4 Power Electronics Application Trends § Traditional: More Compact and Powerful Systems § Modern: Better Quality and Reliability § Efficient: Lower Losses § Custom: Niche and Special Applications § Solid State: DC Breakers, Transformers § Environmental: Renewable Energy Sources, Electric/Hybrid Cars © ABB Group May 16, 2014 | Slide 5 The Semiconductor Revolution Sub-module section System Valve PIN Wafer Module IGBT 1947: Bell`s Transistor Today: GW IGBT based HVDC systems © ABB Group May 16, 2014 | Slide 6 Semiconductors, Towards Higher Speeds & Power § It took close to two decades after the invention of the solid-state bipolar transistor (1947) for semiconductors to hit mainstream applications § The beginnings of power semiconductors came at a similar time with the integrated circuit in the fifties § Both lead to the modern era of advanced DATA Kilby`s first IC in 1958 and POWER processing § While the main target for ICs is increasing the speed of data processing, for power devices it was the controlled power handling capability § Since the 1970s, power semiconductors have benefited from advanced Silicon material and technologies/ processes developed for the much larger and well funded IC applications and markets Robert N. Hall (left) at GE demonstrated the first 200V/35A Ge power diode in 1952 © ABB Group May 16, 2014 | Slide 7 The Global Semiconductor Market and Producers © ABB Group May 16, 2014 | Slide 8 Power Semiconductors; the Principle Power Semiconductor Current flow direction Switches Rectifiers (MOSFET, IGBT, Thyistor) (Diodes) © ABB Group May 16, 2014 | Slide 9 Power Semiconductor Device Main Functions Logic Device High Power Device § Main Functions of the power device: Switch § Support the off-voltage (Thousands of Volts) § Conduct currents when switch is on (Hundreds of Amps per cm2) © ABB Group May 16, 2014 | Slide 10 Silicon Switch/Diode Classification Si Power Devices BiPolar BiMOS UniPolar Thyristors IGBT MOSFET GTO/IGCT BJT JFET (Lat. & Ver.) (Lat. & Ver.) Triac § Current drive § Current drive § Voltage drive § Voltage drive § Voltage drive § up to 10kV § up to 2kV § up to 6.5kV § few 100V § up to 1.2kV PIN Diode SB Diode § up to 13kV § few 100V © ABB Group May 16, 2014 | Slide 11 Evolution of Silicon Based Power Devices PCT/Diode Bipolar evolving Technologies GTO IGCT evolving BJT MOSFET evolving MOS IGBT Technologies evolving Ge → Si 1960 1970 1980 1990 2000 2010 © ABB Group May 16, 2014 | Slide 12 Silicon, the main power semiconductor material § Silicon is the second most common chemical element in the crust of the earth (27.7% vs. 46.6% of Oxygen) § Stones and sand are mostly consisting of Silicon and Oxygen (SiO2) § For Semiconductors, we need an almost perfect Silicon crystal § Silicon crystals for semiconductor applications are probably the best organized structures on earth § Before the fabrication of chips, the semiconductor wafer is doped with minute amounts of foreign atoms (p “B, Al” or n “P, As” type doping) © ABB Group May 16, 2014 | Slide 13 Power Semiconductor Processes § It takes basically the same technologies to manufacture power semiconductors like modern logic devices like microprocessors § But the challenges are different in terms of Device Physics and Application Critical Min. doping Max. Process Device Dimension concentration Temperature* 1050 - 1100°C Logic Devices 0.1 - 0.2 µm 1015 cm-3 (minutes) 1250°C MOSFET, IGBT 1 - 2 µm 1013 - 1014 cm-3 (hours) Thyristor, GTO, IGCT 10 -20 µm < 1013 cm-3 1280-1300°C(days) melts at 1360°C § Doping and thickness of the silicon must be tightly controlled (both in % range) § Because silicon is a resistor, device thickness must be kept at absolute minimum § Virtually no defects or contamination with foreign atoms are permitted © ABB Group May 16, 2014 | Slide 14 Power Semiconductors Understanding The Basics © ABB Group May 16, 2014 | Slide 15 … without diving into semiconductor physics … - 1.50 - 1.00 - 0.50 0.00 ionising radiation0.50 1.00 1.50 - - - 20 15 10 10 15 20 - 5 electron “knocked out of orbit” 0 5 E = energy of electron conduction band 0 band gap 0.5 allowable valance band energy levels 1 nucleus 1.5 core band 2 r = distance from nucleus 2.5 + + + + + + + + + Si Si − − − − Conduction Band Conduction Band Conduction Band − − − Si Si Si Si − − − − − Valence Band Band Gap − − Valence Band − − − Si Si Si Si − − − Valence Band − − − − Si Si Metal Semiconductor Insulator (ρ ≈ 10-6 Ω-cm) (ρ ≈ 102…6 Ω-cm) (ρ ≈ 1016 Ω-cm) Power Semiconductors, S. Linder, EPFL Press ISBN 2-940222-09-6 © ABB Group May 16, 2014 | Slide 16 The Basic Building Block; The PN Junction electric field p-type n-type − − − − − − − − − − − − − − − − + + + + + + + + − − − − − − − − Anode − − − − − − − − + + + + + + + Cathode − − − − − − − − + + + + + + + + − − − − − − − − junction + donors − acceptors holes electrons EC No Bias EF EV Forward Bias e P(+)N(-) Space-charge region abolished and a current starts to flow if the external voltage exceeds the “built- h in” voltage ~ 0.7 V Reverse Bias P(-)N(+) Space-charge region expands and avalanche break-down voltage is reached at critical electric field for Si 5 (2x10 V/cm) © ABB Group May 16, 2014 | Slide 17 The PIN Bipolar Power Diode The low doped drift (base) region is the main differentiator for power devices (normally n-type) Poisson’s Equation for Electric Field Charge Density Permittivity ρ = q (p – n + ND – NA) © ABB Group May 16, 2014 | Slide 18 Power Diode Structure and Doping Profile The Power Diode in Reverse Blocking Mode 0.000005 Vpt 0.000004 Vbd 0.000003 Current (Amp) 0.000002 I s 0.000001 0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 Voltage (Volt) 13 −3/4 Non - Punch Through Breakdown Voltage Vbd = 5.34 ×10 ND −12 Vpt = 7.67 ×10 NDWB Punch Through Voltage • All the constants on the right hand side of the above equations have units which will result in a final unit in (Volts). © ABB Group May 16, 2014 | Slide 19 Power Diode Reverse Blocking Simulation (1/5) 1.0E+19 2.1E+05 1.0E+18 1.8E+05 1.0E+17 1.5E+05 1.0E+16 1.2E+05 1.0E+15 9.0E+04 1.0E+14 6.0E+04 Electric Field [V/cm] Field Electric VR=100V Carrier ConcentrationCarrier[cm-3] 1.0E+13 3.0E+04 Electric Field 1.0E+12 0.0E+00 0 100 200 300 400 500 600 depth [um] © ABB Group May 16, 2014 | Slide 20 Power Diode Reverse Blocking Simulation (2/5) 1.0E+19 2.1E+05 1.0E+18 1.8E+05 1.0E+17 1.5E+05 1.0E+16 1.2E+05 1.0E+15 9.0E+04 1.0E+14 VR=1000V 6.0E+04 Electric Field [V/cm] Field Electric Carrier ConcentrationCarrier[cm-3] 1.0E+13 3.0E+04 Electric Field 1.0E+12 0.0E+00 0 100 200 300 400 500 600 depth [um] © ABB Group May 16, 2014 | Slide 21 Power Diode Reverse Blocking Simulation (3/5) 1.0E+19 2.1E+05 1.0E+18 1.8E+05 1.0E+17 1.5E+05 1.0E+16 1.2E+05 1.0E+15 VR=2000V 9.0E+04 1.0E+14 Electric Field 6.0E+04 Electric Field [V/cm] Field Electric Carrier ConcentrationCarrier[cm-3] 1.0E+13 3.0E+04 1.0E+12 0.0E+00 0 100 200 300 400 500 600 depth [um] © ABB Group May 16, 2014 | Slide 22 Power Diode Reverse Blocking Simulation (4/5) 1.0E+19 2.1E+05 1.0E+18 1.8E+05 1.0E+17 1.5E+05 1.0E+16 VR=4000V 1.2E+05 1.0E+15 Electric Field 9.0E+04 1.0E+14 6.0E+04 Electric Field [V/cm] Field Electric Carrier ConcentrationCarrier[cm-3] 1.0E+13 3.0E+04 1.0E+12 0.0E+00 0 100 200 300 400 500 600 depth [um] © ABB Group May 16, 2014 | Slide 23 Power Diode Reverse Blocking Simulation (5/5) 1.0E+19 2.1E+05 1.0E+18 VR=7400V 1.8E+05 IR=1A 1.0E+17 1.5E+05 Electric Field 1.0E+16 1.2E+05 1.0E+15 9.0E+04 1.0E+14 6.0E+04 Electric Field [V/cm] Field Electric Carrier ConcentrationCarrier[cm-3] 1.0E+13 3.0E+04 1.0E+12 0.0E+00 0 100 200 300 400 500 600 depth [um] © ABB Group May 16, 2014 | Slide 24 Power Diode in Forward Conduction Mode 5000 4500 4000 Vf = Vpn +VB +Vnn 3500 3000 2500 Current (Amp) Current 2000 1500 Vo 1/Ron 1000 500 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 Voltage (Volt) 2kT WB 2 VB = ( ) Base (Drift) Region Voltage Drop q 2La © ABB Group May 16, 2014 | Slide 25 Power Diode Forward Conduction Simulation (1/5) 1.0E+19 Cathode 1.0E+18 Anode 1.0E+17 e- 1.0E+16 h+ 1.0E+15 1.0E+14 Carrier Concentration [cm-3] 1.0E+13 1.0E+12 0 100 200 300 400 500 600 depth [um] © ABB Group May 16, 2014 | Slide 26 90 80 Forward Conduction Simulation (2/5) 70 60 50 IF [A] 40 30 1.0E+19 20 eDensity 10 hDensity 0 1.0E+18 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 DopingConcentration VF [V] 1.0E+17 1.0E+16 1.0E+15 1.0E+14 Carrier Concentration