Devices and their Packaging Technology

4 th Workshop Future of Electronic Power Processing and Conversion Devices and their Packaging Technology May 2001 Werner Tursky SEMIKRON ELEKTRONIK GmbH Nuremberg, Germany 1

1. Devices 2. From Discrete Components to Power Electronic Systems 3. Packaging Technology 4. Cooling 5. Passive Components 6. High Temperature Power Electronics 7. Summary Devices and their Packaging Technology 2

1. Devices Enabling Technologies Semiconductor Materials Rectifiers Switches 2. From Discrete Components to Power Electronic Systems 3. Packaging Technology 4. Cooling 5. Passive Components 6. High Temperature Power Electronics 7. Summary Devices and their Packaging Technology 3

Devices Thin Wafer Technology 100 µm / 6 60 µm / 6 8 Super Junction implantation, trench, expensive cost effective SOI expensive low power cost effective 2001 2006 2011 Enabling Technologies for Power Semiconductors 4

Devices SiC Wafer micro pipes, 4 quality for large area devices, 6 8 FZ Silicon GaN, Diamond??? 2001 2006 2011 Enabling Technologies for Power Semiconductors 5

Devices Rectifier Diodes 10 000 V / 8 000 A Schottky diodes up to 200V continuous development Free Wheeling Diodes (silicon based) trench structures, merged pin Schottky, hybrid diode radiation technique, controlled emitter efficiency 6 500 V 8 000 V switched emitter? super junction Free Wheeling Diodes (not silicon based) GaAs SiC (Schottky) 1 200 V / 20 A 2 500 V / 100 A SiC (pin) 5 000 V / 200 A??? GaN,diamond 2001 2006 2011 Diodes 6

Devices Thyristor continuous development Light Triggered Thyristor 8 000 V / 4 000 A GTO, (I)GCT (I)GCT 4 500 V IGCT with integrated diode 8 000 V 10 000 V MCT, MTO, EST (Thyristor Cascode) samples 6 000 V / 1 000 A only for soft switching? hybrid or monolithic? wafer bonding? 2001 2006 2011 Thyristors 7

Devices Low Voltage MOSFET trench technology > 100 million cells/inch² continuous development High Voltage MOSFET super junction 600 V super junction 500 V...1 000 V hybrid or monolithic? super junction 1 200 V SiC JFET cascoded with Si MOSFET SiC Si 2001 2006 2011 Field Effect Transistors 8

Devices Darlington no new development 1 400 V / 200 A buffer layer super junction IGBT? IGBT trench 600/1200 V planar 6 500 V trench 3 300 V planar 8 000 V trench 8 000V reverse blocking IGBT (1200 V/60A) market for reverse blocking IGBT? lateral IGBT 1200 V / 5 A lateral IGBT 1200 V / 10 A 2001 2006 2011 Bipolar Transistors 9

Devices Monolithic Bidirectional Switch (R. Sittig) idea feasibility study first devices? Dielectric Charge Trap Devices (D. Silber) idea feasibility study first devices? 2001 2006 2011 New Device Ideas 10

1. Devices 2.From Discrete Components to Power Electronic Systems Technology Driver Monolithic vs. Hybrid Integration Functions and Interfaces 3. Packaging Technology 4. Cooling 5. Passive Components 6. High Temperature Power Electronics 7. Summary Devices and their Packaging Technology 11

From Discrete Components to Power Electronic Systems Technology Drivers: Cost Reliability Size / weight Easy to use in many applications Short time to market From Discrete Components to Power Electronic Systems 12

From Discrete Components to Power Electronic Systems increasing complexity Monolithic Integration for low power power range is growing Hybrid Integration: 4 Stages module intelligent module IPM intelligent subsystem intelligent power electronic system Challenge known good die static and dynamic measurement of chip parameters at full load conditions Monolithic vs. Hybrid Integration 13

From Discrete Components to Power Electronic Systems main battery auxiliary power supply motor control PWM control contactor DC-link charge circuit gate driver protection Module DC-link 3-phase bridge temperature sensor IPM Intelligent Subsystem Intelligent Power Electronic System heatsink cooling system motor current sensor speed sensor From Module to Intelligent Power Electronic System (Example: Automotive Drive System) 14

From Discrete Components to Power Electronic Systems Hitachi HV IC Blocking voltage: 500 V Motor current: 5 A unisolated package Monolithic Integration of Power Switches, Driver and Protection Circuits 15

From Discrete Components to Power Electronic Systems TrilithIC mit 2 low side-chips und 1 Doppel-high side-chip mit Schutz- und Diagnosefunktionen Mini DIP IPM ASIPM (Application Specific IPM) Intelligent Power Modules in Isolated Packages 16

From Discrete Components to Power Electronic Systems 6 IGBTs 1200 V / 600 A with free wheeling diodes, sensors for current, temperature and voltage, protection and driver circuits and auxiliary power supply SKiiP : More than an Intelligent Power Module 17

From Discrete Components to Power Electronic Systems SKiiP Solution input rectifier 3-phase inverter brake chopper electrical isolation sensors for voltage, current and temperature protection circuits driver DC link heat sink cooling fan Intelligent Integrated Subsystem 18

From Discrete Components to Power Electronic Systems Standardisation of signal interface sensor interface power interface user friendly rating system Diagnosis actual state state of health remote control Interfaces 19

1. Devices 2. From Discrete Components to Power Electronic Systems 3.Packaging Technology Reduced Complexity Interconnect Technologies Inductances and Resistances Tools 4. Cooling 5. Passive Components 6. High Temperature Power Electronics 7. Summary Devices and their Packaging Technology 20

Packaging Technology FROM: SEMIPACK Gate terminal (silver) Cathode terminal ( Trimetal = Cu-Fe/Ni-Cu Buffer disk (molybdenum) Thyristor (silicon) anode terminal (copper) TO: pressurer SKiiP pressure DBC-substrate Cu-Al 2 O 3 -Cu Baseplate (copper) collector terminal (copper) bonding wire (aluminium) IGBT-chip (silicon) emitter terminal (copper) (grey layers: solder) DBC-substrate Cu-Al 2 O 3 -Cu (grey layers: solder) Module Construction: Reduced Complexity 21

Packaging Technology 2 thyristors/module, I tav (85 C)=95A, 1600V Semipack 1, 1975 Semitop, 1999 Module weight (g) 160 19 Weight efficiency (%) 0.15 1.3 Package footprint (cm 2 ) 18.6 11.3 Area efficency (%) 16.6 27.4 R thjh (K/W) 0.3 0.225 # of assembly parts 22 5 # of solder layers 5 1 Packaging Improvements 22

Packaging Technology Wire bonding Soldered flexible layer silicon chip solder bonding wire Solder balls DBC substrate flexible layer Pressure contact p r e s s u r e solder pressure solder balls underfill copper copper post Interconnect Technologies: Wire Bonding, Soldering, Pressure Contact flexible copper-isolator-copper sandwich 23

Packaging Technology Wire bonding Soldered flexible layer silicon chip solder bonding wire DBC substrate flexible layer solder Advantages: flexible, automatic process great experience Disadvantages: slightly higher inductance and resistance Advantages: low inductance Disadvantages: limited thermal cycling capability complicated process Interconnect Technologies: Wire Bonding vs. Soldered Flexible Layer 24

Packaging Technology Solder balls Pressure contact p r e s s u r e pressure solder balls underfill copper copper post flexible copper-isolator-copper sandwich Advantages: low inductance Disadvantages: limited thermal cycling capability complicated process high cost Advantages: low inductance high reliability simple process Disadvantages: pressure system necessary Interconnect Technologies: Solder Balls vs. Pressure Contact Technology 25

Packaging Technology AlN Substrates Si 3 N 4 Substrates Diamond Substrates Lead Free Solder NTV NTV (low temperature joining) replaces soldering 2001 2006 2011 Materials and Technologies 26

Packaging Technology Today in low voltage MOSFET applications current is often limited by the ohmic resistance of the bonding wires and of the copper on the substrates. Integration requires mounting of power chips and of devices with high pin count (fine pitch) on the same substrate. Need for thick and thin conductors on one substrate power semiconductor high current conductor wire bond SMD-device signal line with cross over isolating substrate Parasitic Ohmic Resistance 27

Packaging Technology Influence of the DBC layout: simulation of the current density in a MOSFET half bridge during commutation: Other topics: bonding wires vs. ribbon connection to bus bar inductance of capacitors Parasitic Inductance 28

Packaging Technology My dream: All in One Solution for 3D device simulation circuit simulation (including switching behaviour and parasitics) 3D mechanical and thermal simulation 3D CAD reliability simulation Simulation / CAD Tools 29

1. Devices 2. From Discrete Components to Power Electronic Systems 3. Packaging Technology 4.Cooling New Materials Thermal Interface 5. Passive Components 6. High Temperature Power Electronics 7. Summary Devices and their Packaging Technology 30

Cooling Target high thermal conductivity CTE fits to the isolating substrates or to the baseplate easy to produce (castable, machinable) low cost Materials AlSiC AlN silicon carbide impregnated with aluminium aluminium nitride Si 3 N 4 silicon nitride carbon foam 2001 high pressure drop 2006 2010 New Heat Sink Materials 31

Cooling Methods heat pipes evaporation cooling spray cooling Thermal grease is the greatest obstacle for the heat can their thermal properties be improved by a factor of 10? can we get rid of the thermal paste? New Heat Sink Methods 32

1. Devices 2. From Discrete Components to Power Electronic Systems 3. Packaging Technology 4. Cooling 5.Passive Components Problems and Drawbacks New Developments Integration 6. High Temperature Power Electronics 7. Summary Devices and their Packaging Technology 33

Passive Components Passive Components are bulky heavy expensive capacitors Passive Components have limited temperature range low reliability (electrolytic capacitors) parasitic effects choke power semiconductor Situation 34

Passive Components Development of planar power passives (inductors - capacitor - transformers) higher power densities improved thermal management Integration of the passive components into the power semiconductor level of the system Adaptation of the semiconductor packaging technology to the special needs of integrated passives easy connection of active and passive components Integration of Power Passives 35

Passive Components Make parasitics to a part of the distributed integrated passives, use them instead always fighting against them Discrete passive components: Development of new magnetic materials Development of new materials for electrolytic capacitors Increase of the reliability of electrolytic capacitors Lower ohmic and inductive resistance of electrolytic capacitors Future of Passive Components 36

1. Devices 2. From Discrete Components to Power Electronic Systems 3. Packaging Technology 4. Cooling 5. Passive Components 6.High Temperature Power Electronics Devices Materials Packaging Technology for High Temperature 7. Summary Devices and their Packaging Technology 37

High Temperature Power Electronics Active Components: Silicon Carbide Silicon (depending on blocking voltage 125 C to 200 C) Other semiconductor materials (GaAs, GaN) Passive Component: Capacitors Magnetics Packaging Materials: Material for housing (higher T g plastics) Soft mould Packaging Technology Soldering Bonding (improved wire bonding technology) The Challenge High Temperature 38

High Temperature Power Electronics Today 1 st Step 2 nd Step 1) Temperature T a T c T j T a T c T j T a T c T j Range 80 C 125 C 150 C 105 C 150 C 175 C 130 C 175 C 200 C 2) Packaging a) Solder T s = 180 220 C T s = 200 245 C? T s = 230 280 C? b) Thermoplastic T max =140 C/10000h T max =160 C/10000h? T max =180 C/10000h? material 180 C/1000h 200 C/1000h? 220 C/1000h? (flame retardants ) c) Silicone soft mould T max >150 C T max >175 C? T max >200 C? d) Wire bonding standard improved improved? 3) Reliability a) Power cycling 100% 10% 1% b) Temperature cycling -45/+125 C >100 cycl. ( >1000 cycles) -45/+150 C -45/+175 C Step by Step 39

High Temperature Power Electronics Comparison of Power Cycling Results: soldering (blue lines) versus diffusion sintering (NTV, red lines) between chips and substrate 0,400 Thermal Resistance in Power Cycling Test T c,min =40 C, T j,max =128 C Thermal Resistance Rthjc [K/W] 0,350 0,300 0,250 0,200 0,150 0 10 20 30 40 50 60 Power Cycles [in thousands] soldered chip (1) soldered chip (2) diffusion sintered (1) diffusion sintered (2) Increase of Power Cycling Capability by NTV 40

In the next 10 years the dominating devices will be MOSFETs for low voltage and IGBTs for high voltage applications. Both will be made of silicon the degree of integration will rise distinctly. Hybrid integration will dominate for power levels >1 kw new interconnect technologies will replace wire bonding. Pressure contact technology is the most viable solution to cope with reliability requirements the integration of power passives will improve performance and power density simulation tools will cover all aspects of power management Summary 42

Thank You for Your Attention 43