FABRICATION ENGINEERING MICRO- NANOSCALE ATTHE AND. Fourth Edition STEPHEN A. CAMPBELL. of Minnesota. University OXFORD UNIVERSITY PRESS

Transcription

1 AND FABRICATION ENGINEERING ATTHE MICRO- NANOSCALE Fourth Edition STEPHEN A. CAMPBELL University of Minnesota New York Oxford OXFORD UNIVERSITY PRESS

2 CONTENTS Preface xiii prrt i OVERVIEW AND MATERIALS CHRPTER AN INTRODUCTION TO MICROELECTRONIC FABRICATION Microelectronic Technologies: A Simple Example 5 Unit Processes and Technologies 7 A Roadmap Summary 9 for the Course 8 CHRPTER a SEMICONDUCTOR SUBSTRATES Phase Diagrams and Solid Solubility0 2.2 Crystallography and Crystal Structure0 2.3 Crystal Defects Czochralski Growth Bridgman Growth of GaAs Float Zone and Other Growth Wafer Preparation and Specifications 2.8 Summary and Future Trends Problems 36 References 38 prrt ii UNIT PROCESSES I: HOT PROCESSING AND ION IMPLANTATION 41 CHRPTER DIFFUSION 43 Fick's Diffusion Equation in One Dimension Atomistic Models of Diffusion 45 Analytic Solutions of Fick's Law 50 Diffusion Coefficients for Common Dopants Analysis of Diffused Profiles This section provides background material. V

3 * This section contains advanced material and can be omitted without loss of the basic content of the course. CONTENTS 3.6 Diffusion in Si Simulations of Diffusion Profiles Summary 70 Problems 70 References 72 CHRPTER THERMAL OXIDATION 75 The Deal-Grove Model of Oxidation 75 The Linear and Parabolic Rate Coefficients 78 The Initial Oxidation Regime 82 The Structure of Si02 85 Oxide Characterization 86 The Effects of Dopants During Oxidation and Polysilicon Oxidation Silicon Oxynitrides 96 Alternative Gate Insulators+ 97 Oxidation Systems 99 Numeric Oxidations+ 101 Summary 102 Problems 104 References CHRPTER 5 ION IMPLANTATION Idealized Ion Implantation Systems Coulomb Scattering Vertical Projected Range Channeling and Lateral Projected Range Implantation Damage Shallow Junction Formation Buried Dielectrics* Ion Implantation Systems: Problems and Concerns Numerical Implanted Profiles* Summary 139 Problems 140 References 142 CHRPTER B RAPID THERMAL PROCESSING Gray Body Radiation, Heat Exchange, and Optical Absorption High Intensity Optical Sources and Chamber Design Temperature Measurement Thermoplastic Stress" Rapid Thermal Activation of Impurities Rapid Thermal Processing of Dielectrics Silicidation and Contact Formation Alternative Rapid Thermal Processing Systems Summary 165 Problems 166 References 166

4 Contents vii prrtiii UNIT PROCESSES 2: PATTERN TRANSFER 173 CHHPTER 7 OPTICAL LITHOGRAPHY Lithography Overview Diffraction" The Modulation Transfer Function and Optical Exposures Source Systems and Spatial Coherence Contact/Proximity Printers 190 Projection Printers 194 Advanced Mask Concepts Surface Reflections and Standing Waves Alignment 206 Summary 207 Problems 208 References HRPTER B PHOTORESISTS Photoresist Types Organic Materials and Polymers Typical Reactions of DQN Positive Photoresist Contrast Curves The Critical Modulation Transfer Function Applying and Developing Photoresist Second-Order Exposure Effects Advanced Photoresists and Photoresist Processes* Summary 233 Problems 233 References 235 CHRPTER3 NONOPTICAL LITHOGRAPHIC TECHNIQUES Interactions of High Energy Beams with Matter Direct-Write Electron Beam Lithography Systems Direct-Write Electron Beam Lithography: Summary and Outlook X-ray and EUV Sources" Proximity X-ray Exposure Systems Membrane Masks for Proximity X-ray EUV Lithography Projection Electron Beam Lithography (SCALPEL) E-beam and X-ray Resists Radiation Damage in MOS Devices Soft Lithography and Nanoimprint Lithography Summary 265 Problems 265 References 266

5 CONTENTS CHRPTER ID VACUUM SCIENCE AND PLASMAS The Kinetic Theory of Gases" 271 Gas Flow and Conductance 274 Pressure Ranges and Vacuum Pumps 277 Vacuum Seals and Pressure Measurement 283 The DC Glow Discharge0 285 RF Discharges 287 High Density Plasmas 289 Summary 292 Problems 293 References CHRPTER 11 ETCHING Wet Etching Chemical Mechanical Polishing Basic Regimes of Plasma Etching High Pressure Plasma Etching Ion Milling Reactive Ion Etching Damage in Reactive Ion Etching"1" High Density Plasma (HDP) Etching Liftoff Summary 328 Problems 328 References 330 prrtiu UNIT PROCESSES 3: THIN FILMS 337 CHRPTER PHYSICAL DEPOSITION: EVAPORATION AND SPUTTERING Phase Diagrams: Sublimation and Evaporation0 340 Deposition Rates 341 Step Coverage 345 Evaporator Systems: Crucible Heating Techniques 348 Multicomponent Films 350 An Introduction to Sputtering 351 Physics of Sputtering0 352 Deposition Rate: Sputter Yield 354 High Density Plasma Sputtering 357 Morphology and Step Coverage 358 Sputtering Methods 361 Sputtering of Specific Materials 363 Stress in Deposited Layers 366 Summary 367 Problems 368 References

6 Contents ix CHRPTER CHEMICAL VAPOR DEPOSITION 374 A Simple CVD System for the Deposition of Silicon 375 Chemical Equilibrium and the Law of Mass Action" 376 Gas Flow and Boundary Layers0 380 Evaluation of the Simple CVD System 384 Atmospheric CVD of Dielectrics 385 Low Pressure CVD of Dielectrics and Semiconductors in Hot Wall Systems Plasma-enhanced CVD of Dielectrics 392 Metal CVD+ 395 Atomic Layer Deposition 398 Electroplating Copper 401 Summary 403 Problems 403 References CHRPTER EPITAXIAL GROWTH 410 Wafer Cleaning and Native Oxide Removal The Thermodynamics of Vapor Phase Growth Surface Reactions 420 Dopant Incorporation 421 Defects in Epitaxial Growth 422 Selective Growth Halide Transport GaAs Vapor Phase Epitaxy 425 Incommensurate and Strained Layer Heteroepitaxy Metal Organic Chemical Vapor Deposition (MOCVD) Advanced Silicon Vapor Phase Epitaxial Growth Techniques Molecular Beam Epitaxy Technology 438 BCF Theory"1" 443 Gas Source MBE and Chemical Beam Epitaxy+ 448 Summary 449 Problems 449 References phht u PROCESS INTEGRATION 457 CHRPTER IS DEVICE ISOLATION, CONTACTS, AND METALLIZATION Junction and Oxide Isolation LOCOS Methods Trench Isolation Silicon-on-Insulator Isolation Techniques Semi-insulating Substrates Schottky Contacts Implanted Ohmic Contacts Alloyed Contacts Multilevel Metallization Planarization and Advanced Interconnect 486

7 CONTENTS Summary Problems References CHRPTER IB CMOS TECHNOLOGIES 499 Basic Long-Channel Device Behavior 499 Early MOS Technologies 502 The Basic 3-u.m Technology 503 Device Scaling 507 Hot Carrier Effects and Drain Engineering 515 Latchup 518 Shallow Source/Drains and Tailored Channel Doping 521 The Universal Curve and Advanced CMOS 524 A Nanoscale CMOS Process 525 Nonplanar CMOS 527 Summary 529 Problems 529 References 532 CHAPTER 17 OTHER TRANSISTOR TECHNOLOGIES Basic MESFET Operation 538 Basic MESFET Technology 539 Digital Technologies 541 MMIC Technologies 545 MODFETs 547 Review of Bipolar Devices: Ideal and Quasi-ideal Behavior 549 Performance of BJTs 550 Early Bipolar Processes 553 Advanced Bipolar Processes 556 BiCMOS 563 Thin Film Transistors 565 Summary 568 Problems 569 References 572 CHAPTER IB OPTOELECTRONIC AND SOLAR TECHNOLOGIES Optoelectronic Devices Overview 578 Direct-Gap Inorganic LEDs 579 Polymer/Organic Light-Emitting Diodes 583 Lasers 585 Photovoltaic Devices Overview 586 Silicon Based Photovoltaic Device Fabrication 587 Other Photovoltaic Technologies 590 Summary 592 References CHRPTER13 MEMS Fundamentals of Mechanics Stress in Thin Films 598

8 Contents xi 19.3 Mechanical-to-Electrical Transduction Mechanics of Common MEMS Devices Bulk Micromachining Etching Techniques Bulk Micromachining Process Flow Surface Micromachining Basics Surface Micromachining Process Flow MEMS Actuators High Aspect Ratio Microsystems Technology (HARMST) Microfluidics Summary 638 Problems 640 References 642 APPENDIX I. ACRONYMS AND COMMON SYMBOLS 647 APPENDIX II. PROPERTIES OF SELECTED SEMICONDUCTOR MATERIALS 653 APPENDIX III. PHYSICAL CONSTANTS 654 APPENDIX IV CONVERSION FACTORS 656 APPENDIX V. SOME PROPERTIES OF THE ERROR FUNCTION 659 Index 663