Embed Size (px)
Citation preview
Semiconductor Power Devices
Josef Lutz · Heinrich Schlangenotto ·Uwe Scheuermann · Rik De Doncker
Semiconductor PowerDevices
Physics, Characteristics, Reliability
123
Prof. Dr. -Ing. Prof. h.c. Josef LutzChemnitz University of TechnologyFaculty of ET/ITChair Power Electronics andElectromagnetic CompatibilityReichenhainer Str. 70D-09126 [email protected]
Prof. Dr. Heinrich SchlangenottoStoltzestr. 86D-63262 [email protected]
Dr. Uwe ScheuermannSemikron Elektronik GmbH & Co. KGSigmundstr. 200D-90431 Nü[email protected]
Prof. Dr. ir. Rik De DonckerRWTH Aachen UniversityFaculty of ET&ITChair Power Generation and StorageSystems (PGS) at E.ON ERCMathieustrasse 6D-52074 [email protected]
ISBN 978-3-642-11124-2 e-ISBN 978-3-642-11125-9DOI 10.1007/978-3-642-11125-9Springer Heidelberg Dordrecht London New York
Library of Congress Control Number: 2010934110
© Springer-Verlag Berlin Heidelberg 2011This work is subject to copyright. All rights are reserved, whether the whole or part of the material isconcerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcastingreproduction on microfilm or in any other way, and storage in data banks. Duplication of this publicationor parts thereof is permitted only under the provisions of the German Copyright Law of September 9,1965, in its current version, and permission for use must always be obtained from Springer. Violationsare liable to prosecution under the German Copyright Law.The use of general descriptive names, registered names, trademarks, etc. in this publication does notimply, even in the absence of a specific statement, that such names are exempt from the relevantprotective laws and regulations and therefore free for general use.
Cover design: eStudio Calamar S.L., Heidelberg
Printed on acid-free paper
Springer is part of Springer Science+Business Media (www.springer.com)
Preface
Power electronics is gaining more and more importance in industry and society. Ithas the potential to substantially increase the efficiency of power systems, a taskof great significance. To exploit this potential, not only engineers working in thedevelopment of improved and new devices but also application engineers in the fieldof power electronics need to understand the basic principles of semiconductor powerdevices. Furthermore, since a semiconductor device can only fulfil its function in asuitable environment, interconnection and packaging technologies with the relatedmaterial properties have to be considered as well as the problem of cooling, whichhas to be solved for reliable applications.
This book was written for students and for engineers working in the field ofpower device design and power electronics application. The focus was set on mod-ern semiconductor switches such as power MOSFETs and IGBTs together with theessential freewheeling diodes. The engineer in practice may start his work with thebook with the specific power device. Each chapter presents first the device structureand the generic characteristics and then a more thorough discussion is added withthe focus on the physical function principles. The in-depth discussions require theprinciples of semiconductor physics, the functioning of pn-junctions, and the basicsof technology. These topics are treated in depth such that the book will also be ofvalue for the semiconductor device specialist.
Some subjects are treated in particular detail and presented here for the first timein an English textbook on power devices. In device physics, this is especially theemitter recombination which is used in modern power devices to control forwardand switching properties. A detailed discussion of its influence is given using param-eters characterizing the emitter recombination properties. Furthermore, because ofthe growing awareness of the importance of packaging technique for reliable appli-cations, chapters on packaging and reliability are included. During the developmentof power electronic systems, engineers often are confronted with failures and unex-pected effects with the consequence of time-consuming efforts to isolate the rootcause of these effects. Therefore, chapters on failure mechanisms and oscillationeffects in power circuits are included in this textbook to supply guidance based onlong-time experience.
The book has emerged from lectures on “Power devices” held by J. Lutz atChemnitz University of Technology and from earlier lecture notes on “Power
v
vi Preface
devices” from H. Schlangenotto held at Darmstadt Technical University in 1991–2001. Using these lectures and adding considerable material on new devices,packaging, reliability, and failure mechanisms, Lutz published the German bookHalbleiter-Leistungsbauelemente – Physik, Eigenschaften, Zuverlässigkeit in 2006.The English textbook presented here is far more than a translation; it was consider-ably extended with new material.
The basic chapters on semiconductor properties and pn-junctions and a part ofthe chapter on pin-diodes were revised and enhanced widely by H. Schlangenotto.J. Lutz extended the chapters on thyristors, MOSFETs, IGBTs, and failure mecha-nisms. U. Scheuermann contributed the chapter on packaging technology, reliability,and system integration. R. De Doncker supplied the introduction on power devicesas the key components. All the authors have contributed, however, also to otherchapters not written mainly by themselves.
Several researchers in power devices have supported this work with helpful dis-cussions, support in translations, suggestions, and comments. These are especiallyArnost Kopta, Stefan Linder and Munaf Rahimo from ABB Semiconductors, DieterPolenov from BMW, Thomas Laska, Anton Mauder, Franz-Josef Niedernostheide,Ralf Siemieniec, and Gerald Soelkner from Infineon, Martin Domeij and AndersHallén from KTH Stockholm, Stephane Lefebvre from SATIE, Michael Reschkefrom Secos, Reinhard Herzer and Werner Tursky from Semikron, Wolfgang Bartschfrom SiCED, Dieter Silber from University of Bremen, Hans Günter Eckel from theUniversity of Rostock. Several diploma and Ph.D. students at Chemnitz Universityof Technology have supported part of the work, especially Hans-Peter Felsl, BirkHeinze, Roman Baburske, Marco Bohlländer, Tilo Pollera Matthias Baumann,and Thomas Basler. Thomas Blum and Florian Mura from RWTH Aachen havetranslated the chapter on MOSFETS, and Mary-Joan Blümich has given supportwith improvements of the English text. Finally, the authors thank the many otherresearchers and students in power electronics, who supported this work with criticalcomments and discussions.
Chemnitz, Germany Josef LutzNeu-Isenburg, Germany Heinrich SchlangenottoNürnberg, Germany Uwe ScheuermannAachen, Germany Rik De DonckerMarch 2010
Contents
1 Power Semiconductor Devices – Key Components forEfficient Electrical Energy Conversion Systems . . . . . . . . . . 11.1 Systems, Power Converters, and Power Semiconductor Devices 1
1.1.1 Basic Principles of Power Converters . . . . . . . . . 31.1.2 Types of Power Converters and Selection
of Power Devices . . . . . . . . . . . . . . . . . . . 41.2 Operating and Selecting Power Semiconductors . . . . . . . . 71.3 Applications of Power Semiconductors . . . . . . . . . . . . . 10References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2 Semiconductor Properties . . . . . . . . . . . . . . . . . . . . . . 172.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 172.2 Crystal Structure . . . . . . . . . . . . . . . . . . . . . . . . 192.3 Energy Gap and Intrinsic Concentration . . . . . . . . . . . . 212.4 Energy Band Structure and Particle Properties of Carriers . . . 262.5 The Doped Semiconductor . . . . . . . . . . . . . . . . . . . 302.6 Current Transport . . . . . . . . . . . . . . . . . . . . . . . . 39
2.6.1 Carrier Mobilities and Field Currents . . . . . . . . . 392.6.2 High-Field Drift Velocities . . . . . . . . . . . . . . 452.6.3 Diffusion of Carriers and Current Transport Equations 46
2.7 Recombination-Generation and Lifetimeof Non-equilibrium Carriers . . . . . . . . . . . . . . . . . . 482.7.1 Intrinsic Recombination Mechanisms . . . . . . . . . 502.7.2 Recombination and Generation at
Recombination Centers . . . . . . . . . . . . . . . . 512.8 Impact Ionization . . . . . . . . . . . . . . . . . . . . . . . . 602.9 Basic Equations of Semiconductor Devices . . . . . . . . . . 662.10 Simple Conclusions . . . . . . . . . . . . . . . . . . . . . . . 69References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3 pn-Junctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773.1 The pn-Junction in Thermal Equilibrium . . . . . . . . . . . . 78
3.1.1 The Abrupt Step Junction . . . . . . . . . . . . . . . 803.1.2 Graded Junctions . . . . . . . . . . . . . . . . . . . . 86
vii
viii Contents
3.2 Current–Voltage Characteristics of the pn-Junction . . . . . . 893.3 Blocking Characteristics and Breakdown
of the pn-Junction . . . . . . . . . . . . . . . . . . . . . . . . 983.3.1 Blocking Current . . . . . . . . . . . . . . . . . . . . 983.3.2 Avalanche Multiplication and Breakdown Voltage . . 1013.3.3 Blocking Capability with Wide-Gap Semiconductors . 110
3.4 Injection Efficiency of Emitter Regions . . . . . . . . . . . . . 1113.5 Capacitance of pn-Junctions . . . . . . . . . . . . . . . . . . 118References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
4 Short Introduction to Power Device Technology . . . . . . . . . . 1234.1 Crystal Growth . . . . . . . . . . . . . . . . . . . . . . . . . 1234.2 Neutron Transmutation for Adjustment of the Wafer Doping . 1264.3 Epitaxial Growth . . . . . . . . . . . . . . . . . . . . . . . . 1284.4 Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1294.5 Ion Implantation . . . . . . . . . . . . . . . . . . . . . . . . . 1344.6 Oxidation and Masking . . . . . . . . . . . . . . . . . . . . . 1394.7 Edge Terminations . . . . . . . . . . . . . . . . . . . . . . . 142
4.7.1 Bevelled Termination Structures . . . . . . . . . . . . 1424.7.2 Planar Junction Termination Structures . . . . . . . . 1444.7.3 Junction Termination for Bidirectional
Blocking Devices . . . . . . . . . . . . . . . . . . . 1464.8 Passivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1474.9 Recombination Centers . . . . . . . . . . . . . . . . . . . . . 148
4.9.1 Gold and Platinum as Recombination Centers . . . . 1484.9.2 Radiation-Induced Recombination Centers . . . . . . 1514.9.3 Radiation-Enhanced Diffusion of Pt and Pd . . . . . . 154
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
5 pin-Diodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1595.1 Structure of the pin-Diode . . . . . . . . . . . . . . . . . . . 1595.2 I–V Characteristic of the pin-Diode . . . . . . . . . . . . . . . 1605.3 Design and Blocking Voltage of the pin-Diode . . . . . . . . . 1625.4 Forward Conduction Behavior . . . . . . . . . . . . . . . . . 167
5.4.1 Carrier Distribution . . . . . . . . . . . . . . . . . . 1675.4.2 Junction Voltages . . . . . . . . . . . . . . . . . . . 1705.4.3 Voltage Drop Across the Middle Region . . . . . . . 1725.4.4 Voltage Drop in the Hall Approximation . . . . . . . 1735.4.5 Emitter Recombination, Effective Carrier
Lifetime, and Forward Characteristic . . . . . . . . . 1755.4.6 Temperature Dependency of the Forward Characteristics 183
5.5 Relation Between Stored Charge and Forward Voltage . . . . . 1845.6 Turn-On Behavior of Power Diodes . . . . . . . . . . . . . . 1855.7 Reverse Recovery of Power Diodes . . . . . . . . . . . . . . . 188
5.7.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . 1885.7.2 Reverse Recovery Related Power Losses . . . . . . . 194
Contents ix
5.7.3 Reverse Recovery: Charge Dynamic in the Diode . . . 1985.7.4 Fast Diodes with Optimized Reverse Recovery Behavior 206
5.8 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
6 Schottky Diodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2256.1 Aspects of the Physics of the Metal–Semiconductor
Junction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2256.2 Current–Voltage Characteristics of the Schottky Junction . . . 2276.3 Structure of Schottky Diodes . . . . . . . . . . . . . . . . . . 2306.4 Ohmic Voltage Drop of a Unipolar Device . . . . . . . . . . . 2306.5 Schottky Diodes Based on SiC . . . . . . . . . . . . . . . . . 234References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
7 Bipolar Transistors . . . . . . . . . . . . . . . . . . . . . . . . . . 2417.1 Function of the Bipolar Transistor . . . . . . . . . . . . . . . 2417.2 Structure of the Bipolar Power Transistor . . . . . . . . . . . 2437.3 I–V Characteristic of the Power Transistor . . . . . . . . . . . 2447.4 Blocking Behavior of the Bipolar Power Transistor . . . . . . 2457.5 Current Gain of the Bipolar Transistor . . . . . . . . . . . . . 2477.6 Base Widening, Field Redistribution,
and Second Breakdown . . . . . . . . . . . . . . . . . . . . . 2517.7 Limits of the Silicon Bipolar Transistor . . . . . . . . . . . . 2547.8 SiC Bipolar Transistor . . . . . . . . . . . . . . . . . . . . . 255References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
8 Thyristors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2578.1 Structure and Mode of Function . . . . . . . . . . . . . . . . 2578.2 I–V Characteristic of the Thyristor . . . . . . . . . . . . . . . 2608.3 Blocking Behavior of the Thyristor . . . . . . . . . . . . . . . 2628.4 The Function of Emitter Shorts . . . . . . . . . . . . . . . . . 2648.5 Modes to Trigger a Thyristor . . . . . . . . . . . . . . . . . . 2658.6 Trigger Front Spreading . . . . . . . . . . . . . . . . . . . . . 2668.7 Follow-Up Triggering and Amplifying Gate . . . . . . . . . . 2678.8 Thyristor Turn-Off and Recovery Time . . . . . . . . . . . . . 2708.9 The Triac . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2728.10 The Gate Turn-Off Thyristor (GTO) . . . . . . . . . . . . . . 2738.11 The Gate-Commutated Thyristor (GCT) . . . . . . . . . . . . 279References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
9 MOS Transistors . . . . . . . . . . . . . . . . . . . . . . . . . . . 2839.1 Function Principle of the MOSFET . . . . . . . . . . . . . . . 2839.2 Structure of Power MOSFETs . . . . . . . . . . . . . . . . . 2859.3 Current–Voltage Characteristics of MOS Transistors . . . . . . 2879.4 Characteristics of the MOSFET Channel . . . . . . . . . . . . 2889.5 The Ohmic Region . . . . . . . . . . . . . . . . . . . . . . . 2929.6 Compensation Structures in Modern MOSFETs . . . . . . . . 293
x Contents
9.7 Switching Properties of the MOSFET . . . . . . . . . . . . . 2989.8 Switching Losses of the MOSFET . . . . . . . . . . . . . . . 3029.9 Safe Operating Area of the MOSFET . . . . . . . . . . . . . . 3039.10 The Inverse Diode of the MOSFET . . . . . . . . . . . . . . . 3059.11 SiC Field Effect Devices . . . . . . . . . . . . . . . . . . . . 3099.12 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
10 IGBTs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31510.1 Mode of Function . . . . . . . . . . . . . . . . . . . . . . . . 31510.2 The I–V Characteristic of the IGBT . . . . . . . . . . . . . . 31710.3 The Switching Behavior of the IGBT . . . . . . . . . . . . . . 31910.4 The Basic Types: PT-IGBT and NPT-IGBT . . . . . . . . . . 32110.5 Plasma Distribution in the IGBT . . . . . . . . . . . . . . . . 32510.6 Modern IGBTs with Increased Charge Carrier Density . . . . 327
10.6.1 Plasma Enhancement by High n-Emitter Efficiency . . 32710.6.2 The “Latch-Up Free Cell Geometry” . . . . . . . . . 33110.6.3 The Effect of the “Hole Barrier” . . . . . . . . . . . . 33210.6.4 Collector Side Buffer Layers . . . . . . . . . . . . . 334
10.7 IGBTs with Bidirectional Blocking Capability . . . . . . . . . 33510.8 Reverse Conducting IGBTs . . . . . . . . . . . . . . . . . . . 33710.9 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
11 Packaging and Reliability of Power Devices . . . . . . . . . . . . . 34311.1 The Challenge of Packaging Technology . . . . . . . . . . . . 34311.2 Package Types . . . . . . . . . . . . . . . . . . . . . . . . . . 344
11.2.1 Capsules . . . . . . . . . . . . . . . . . . . . . . . . 34611.2.2 The TO Family and Its Relatives . . . . . . . . . . . 34811.2.3 Modules . . . . . . . . . . . . . . . . . . . . . . . . 353
11.3 Physical Properties of Materials . . . . . . . . . . . . . . . . 35811.4 Thermal Simulation and Thermal Equivalent Circuits . . . . . 360
11.4.1 Transformation Between Thermo-dynamicaland Electrical Parameters . . . . . . . . . . . . . . . 360
11.4.2 One-Dimensional Equivalent Networks . . . . . . . . 36711.4.3 The Three-Dimensional Thermal Network . . . . . . 36911.4.4 The Transient Thermal Resistance . . . . . . . . . . . 370
11.5 Parasitic Electrical Elements in Power Modules . . . . . . . . 37311.5.1 Parasitic Resistances . . . . . . . . . . . . . . . . . . 37311.5.2 Parasitic Inductance . . . . . . . . . . . . . . . . . . 37411.5.3 Parasitic Capacities . . . . . . . . . . . . . . . . . . 378
11.6 Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38011.6.1 The Demand for Increasing Reliability . . . . . . . . 38011.6.2 High Temperature Reverse Bias Test . . . . . . . . . 38311.6.3 High Temperature Gate Stress Test . . . . . . . . . . 38511.6.4 Temperature Humidity Bias Test . . . . . . . . . . . 386
Contents xi
11.6.5 High Temperature and Low TemperatureStorage Tests . . . . . . . . . . . . . . . . . . . . . . 387
11.6.6 Temperature Cycling and Temperature Shock Test . . 38811.6.7 Power Cycling Test . . . . . . . . . . . . . . . . . . 39011.6.8 Additional Reliability Tests . . . . . . . . . . . . . . 41011.6.9 Strategies for Enhanced Reliability . . . . . . . . . . 411
11.7 Future Challenges . . . . . . . . . . . . . . . . . . . . . . . . 412References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416
12 Destructive Mechanisms in Power Devices . . . . . . . . . . . . . 41912.1 Thermal Breakdown – Failures by Excess Temperature . . . . 41912.2 Surge Current . . . . . . . . . . . . . . . . . . . . . . . . . . 42112.3 Overvoltage – Voltage Above Blocking Capability . . . . . . . 42612.4 Dynamic Avalanche . . . . . . . . . . . . . . . . . . . . . . . 432
12.4.1 Dynamic avalanche in Bipolar Devices . . . . . . . . 43212.4.2 Dynamic Avalanche in Fast Diodes . . . . . . . . . . 43312.4.3 Diode Structures with High Dynamic
Avalanche Capability . . . . . . . . . . . . . . . . . 44212.4.4 Dynamic Avalanche: Further Tasks . . . . . . . . . . 446
12.5 Exceeding the Maximum Turn-Off Current of GTOs . . . . . 44612.6 Short-Circuit and Over-Current in IGBTs . . . . . . . . . . . 447
12.6.1 Short-Circuit Types I, II, and III . . . . . . . . . . . . 44712.6.2 Thermal and Electrical Stress in Short Circuit . . . . 45212.6.3 Turn-Off of Over-Current and Dynamic Avalanche . . 460
12.7 Cosmic Ray Failures . . . . . . . . . . . . . . . . . . . . . . 46312.8 Failure Analysis . . . . . . . . . . . . . . . . . . . . . . . . . 468References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 470
13 Power Device-Induced Oscillations and ElectromagneticDisturbances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47513.1 Frequency Range of Electromagnetic Disturbances . . . . . . 47513.2 LC Oscillations . . . . . . . . . . . . . . . . . . . . . . . . . 477
13.2.1 Turn-Off Oscillations with IGBTs Connectedin Parallel . . . . . . . . . . . . . . . . . . . . . . . 477
13.2.2 Turn-Off Oscillations with Snappy Diodes . . . . . . 48013.3 Transit-Time Oscillations . . . . . . . . . . . . . . . . . . . . 483
13.3.1 Plasma-Extraction Transit-Time (PETT) Oscillations . 48313.3.2 Dynamic Impact-Ionization Transit-Time
(IMPATT) Oscillations . . . . . . . . . . . . . . . . . 491References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495
xii Contents
14 Power Electronic Systems . . . . . . . . . . . . . . . . . . . . . . 49714.1 Definition and Basic Features . . . . . . . . . . . . . . . . . . 49714.2 Monolithically Integrated Systems – Power ICs . . . . . . . . 49914.3 System Integration on Printed Circuit Board . . . . . . . . . . 50314.4 Hybrid Integration . . . . . . . . . . . . . . . . . . . . . . . . 505References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512
Appendix A: Modeling Parameters of Carrier Mobilities in Siand 4H-SiC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515
Appendix B: Avalanche Multiplication Factors and EffectiveIonization Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517
Appendix C: Thermal Parameters of Important Materials inPackaging Technology . . . . . . . . . . . . . . . . . . . . . . . . 521
Appendix D: Electric Parameters of Important Materials inPackaging Technology . . . . . . . . . . . . . . . . . . . . . . . . 523
Appendix E: Often Used Symbols . . . . . . . . . . . . . . . . . . . . . 525
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 529
