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Book Details
Abstract
For courses in Micro-Electro-Mechanical Systems (MEMS) taken by advanced undergraduate students, beginning graduate students, and professionals.
Foundations of MEMS is an entry-level text designed to systematically teach the specifics of MEMS to an interdisciplinary audience. Liu discusses designs, materials, and fabrication issues related to the MEMS field by employing concepts from both the electrical and mechanical engineering domains and by incorporating evolving microfabrication technology — all in a time-efficient and methodical manner. A wealth of examples and problems solidify students’ understanding of abstract concepts and provide ample opportunities for practicing critical thinking.
Table of Contents
| Section Title | Page | Action | Price |
|---|---|---|---|
| Cover | Cover | ||
| CONTENTS | 3 | ||
| PREFACE | 10 | ||
| A NOTE TO INSTRUCTORS | 12 | ||
| ABOUT THE AUTHOR | 14 | ||
| Chapter 1 Introduction | 15 | ||
| 1.0 Preview | 15 | ||
| 1.1 The History of MEMS Development | 15 | ||
| 1.1.1 From the Beginning to 1990 | 15 | ||
| 1.1.2 From 1990 to 2001 | 19 | ||
| 1.1.3 2002 to Present | 25 | ||
| 1.1.4 Future Trends | 26 | ||
| 1.2 The Intrinsic Characteristics of MEMS | 27 | ||
| 1.2.1 Miniaturization | 27 | ||
| 1.2.2 Microelectronics Integration | 29 | ||
| 1.2.3 Parallel Fabrication with Precision | 29 | ||
| 1.3 Devices: Sensors and Actuators | 30 | ||
| 1.3.1 Energy Domains and Transducers | 30 | ||
| 1.3.2 Sensors Considerations | 32 | ||
| 1.3.3 Sensor Noise and Design Complexity | 34 | ||
| 1.3.4 Actuators Considerations | 35 | ||
| Summary | 36 | ||
| Problems | 37 | ||
| References | 41 | ||
| Chapter 2 First-Pass Introduction to Microfabrication | 47 | ||
| 2.0 Preview | 47 | ||
| 2.1 Overview of Microfabrication | 47 | ||
| 2.2 Essential Overview of Frequently Used Microfabrication Processes | 51 | ||
| 2.2.1 Photolithography | 51 | ||
| 2.2.2 Thin Film Deposition | 54 | ||
| 2.2.3 Thermal Oxidation of Silicon | 55 | ||
| 2.2.4 Wet Etching | 55 | ||
| 2.2.5 Silicon Anisotropic Etching | 57 | ||
| 2.2.6 Plasma Etching and Reactive Ion Etching | 57 | ||
| 2.2.7 Doping | 58 | ||
| 2.2.8 Wafer Dicing | 59 | ||
| 2.2.9 Wafer Bonding | 60 | ||
| 2.3 The Microelectronics Fabrication Process Flow | 61 | ||
| 2.4 Silicon-Based MEMS Processes | 63 | ||
| 2.5 Packaging and Integration | 69 | ||
| 2.5.1 Integration Options | 69 | ||
| 2.5.2 Encapsulation | 71 | ||
| 2.6 New Materials and Fabrication Processes | 71 | ||
| 2.7 Process Selection and Design | 73 | ||
| 2.7.1 Points of Consideration for Deposition Processes | 73 | ||
| 2.7.2 Points of Consideration for Etching Processes | 73 | ||
| 2.7.3 Ideal Rules for Building a Process Flow | 75 | ||
| 2.7.4 Rules for Building a Robust Process | 75 | ||
| Summary | 77 | ||
| Problems | 77 | ||
| References | 79 | ||
| Chapter 3 Review of Essential Electrical and Mechanical Concepts | 84 | ||
| 3.0 Preview | 84 | ||
| 3.1 Conductivity of Semiconductors | 85 | ||
| 3.1.1 Semiconductor Materials | 85 | ||
| 3.1.2 Calculation of Charge Carrier Concentration | 86 | ||
| 3.1.3 Conductivity and Resistivity | 89 | ||
| 3.2 Crystal Planes and Orientations | 93 | ||
| 3.3 Stress and Strain | 96 | ||
| 3.3.1 Internal Force Analysis: Newton's Laws of Motion | 96 | ||
| 3.3.2 Definitions of Stress and Strain | 98 | ||
| 3.3.3 General Scalar Relation Between Tensile Stress and Strain | 101 | ||
| 3.3.4 Mechanical Properties of Silicon and Related Thin Films | 103 | ||
| 3.3.5 General Stress—Strain Relations | 105 | ||
| 3.4 Flexural Beam Bending Analysis Under Simple Loading Conditions | 107 | ||
| 3.4.1 Types of Beams | 108 | ||
| 3.4.2 Longitudinal Strain Under Pure Bending | 110 | ||
| 3.4.3 Deflection of Beams | 112 | ||
| 3.4.4 Finding the Spring Constants | 113 | ||
| 3.5 Torsional Deflections | 118 | ||
| 3.6 Intrinsic Stress | 120 | ||
| 3.7 Dynamic System, Resonant Frequency, and Quality Factor | 125 | ||
| 3.7.1 Dynamic System and Governing Equation | 125 | ||
| 3.7.2 Response Under Sinusoidal Resonant Input | 126 | ||
| 3.7.3 Damping and Quality Factor | 128 | ||
| 3.7.4 Resonant Frequency and Bandwidth | 128 | ||
| 3.8 Active Tuning of Spring Constant and Resonant Frequency | 129 | ||
| 3.9 A List of Suggested Courses and Books | 130 | ||
| Summary | 131 | ||
| Problems | 132 | ||
| References | 136 | ||
| Chapter 4 Electrostatic Sensing and Actuation | 141 | ||
| 4.0 Preview | 141 | ||
| 4.1 Introduction to Electrostatic Sensors and Actuators | 141 | ||
| 4.2 Parallel-Plate Capacitor | 143 | ||
| 4.2.1 Capacitance of Parallel Plates | 143 | ||
| 4.2.2 Equilibrium Position of Electrostatic Actuator under Bias | 146 | ||
| 4.2.3 Pull-in Effect of Parallel-Plate Actuators | 149 | ||
| 4.3 Applications of Parallel-Plate Capacitors | 154 | ||
| 4.3.1 Inertia Sensor | 155 | ||
| 4.3.2 Pressure Sensor | 160 | ||
| 4.3.3 Flow Sensor | 165 | ||
| 4.3.4 Tactile Sensor | 168 | ||
| 4.3.5 Parallel-Plate Actuators | 170 | ||
| 4.4 Interdigitated Finger Capacitors | 171 | ||
| 4.5 Applications of Comb-Drive Devices | 176 | ||
| 4.5.1 Inertia Sensors | 176 | ||
| 4.5.2 Actuators | 180 | ||
| Summary | 182 | ||
| Problems | 182 | ||
| References | 186 | ||
| Chapter 5 Thermal Sensing and Actuation | 190 | ||
| 5.0 Preview | 190 | ||
| 5.1 Introduction | 190 | ||
| 5.1.1 Thermal Sensors | 190 | ||
| 5.1.2 Thermal Actuators | 191 | ||
| 5.1.3 Fundamentals of Thermal Transfer | 191 | ||
| 5.2 Sensors and Actuators Based on Thermal Expansion | 196 | ||
| 5.2.1 Thermal Bimorph Principle | 198 | ||
| 5.2.2 Thermal Actuators with a Single Material | 205 | ||
| 5.3 Thermal Couples | 207 | ||
| 5.4 Thermal Resistors | 210 | ||
| 5.5 Applications | 212 | ||
| 5.5.1 Inertia Sensors | 213 | ||
| 5.5.2 Flow Sensors | 215 | ||
| 5.5.3 Infrared Sensors | 228 | ||
| 5.5.4 Other Sensors | 231 | ||
| Summary | 236 | ||
| Problems | 236 | ||
| References | 241 | ||
| Chapter 6 Piezoresistive Sensors | 245 | ||
| 6.0 Preview | 245 | ||
| 6.1 Origin and Expression of Piezoresistivity | 245 | ||
| 6.2 Piezoresistive Sensor Materials | 248 | ||
| 6.2.1 Metal Strain Gauges | 248 | ||
| 6.2.2 Single Crystal Silicon | 249 | ||
| 6.2.3 Polycrystalline Silicon | 252 | ||
| 6.3 Stress Analysis of Mechanical Elements | 252 | ||
| 6.3.1 Stress in Flexural Cantilevers | 252 | ||
| 6.3.2 Stress and Deformation in Membrane | 258 | ||
| 6.4 Applications of Piezoresistive Sensors | 260 | ||
| 6.4.1 Inertial Sensors | 260 | ||
| 6.4.2 Pressure Sensors | 266 | ||
| 6.4.3 Tactile Sensor | 268 | ||
| 6.4.4 Flow Sensor | 271 | ||
| Summary | 276 | ||
| Problems | 277 | ||
| References | 281 | ||
| Chapter 7 Piezoelectric Sensing and Actuation | 283 | ||
| 7.0 Preview | 283 | ||
| 7.1 Introduction | 283 | ||
| 7.1.1 Background | 283 | ||
| 7.1.2 Mathematical Description of Piezoelectric Effects | 285 | ||
| 7.1.3 Cantilever Piezoelectric Actuator Model | 287 | ||
| 7.2 Properties of Piezoelectric Materials | 290 | ||
| 7.2.1 Quartz | 290 | ||
| 7.2.2 PZT | 292 | ||
| 7.2.3 PVDF | 293 | ||
| 7.2.4 ZnO | 294 | ||
| 7.2.5 Other Materials | 298 | ||
| 7.3 Applications | 299 | ||
| 7.3.1 Inertia Sensors | 299 | ||
| 7.3.2 Acoustic Sensors | 303 | ||
| 7.3.3 Tactile Sensors | 306 | ||
| 7.3.4 Flow Sensors | 307 | ||
| 7.3.5 Surface Elastic Waves | 309 | ||
| Summary | 311 | ||
| Problems | 311 | ||
| References | 315 | ||
| Chapter 8 Magnetic Actuation | 317 | ||
| 8.0 Preview | 317 | ||
| 8.1 Essential Concepts and Principles | 317 | ||
| 8.1.1 Magnetization and Nomenclatures | 317 | ||
| 8.1.3 Selected Principles of Micro Magnetic Actuators | 321 | ||
| 8.2 Fabrication of Micro Magnetic Components | 326 | ||
| 8.2.1 Deposition of Magnetic Materials | 326 | ||
| 8.2.2 Design and Fabrication of Magnetic Coil | 328 | ||
| 8.3 Case Studies of MEMS Magnetic Actuators | 331 | ||
| Summary | 342 | ||
| Problems | 342 | ||
| References | 344 | ||
| Chapter 9 Summary of Sensing and Actuation Methods | 346 | ||
| 9.0 Preview | 346 | ||
| 9.1 Comparison of Major Sensing and Actuation Methods | 346 | ||
| 9.2 Other Sensing and Actuation Methods | 348 | ||
| 9.2.1 Tunneling Sensing | 348 | ||
| 9.2.3 Optical Sensing | 350 | ||
| 9.2.4 Field Effect Transistors | 356 | ||
| 9.2.5 Radio Frequency Resonance Sensing | 359 | ||
| Summary | 360 | ||
| Problems | 361 | ||
| References | 362 | ||
| Chapter 10 Bulk Micromachining and Silicon Anisotropic Etching | 365 | ||
| 10.0 Preview | 365 | ||
| 10.1 Introduction | 365 | ||
| 10.2 Anisotropic Wet Etching | 367 | ||
| 10.2.1 Introduction | 367 | ||
| 10.2.2 Rules of Anisotropic Etching—Simplest Case | 367 | ||
| 10.2.3 Rules of Anisotropic Etching—Complex Structures | 373 | ||
| 10.2.4 Forming Protrusions | 381 | ||
| 10.2.5 Interaction of Etching Profiles from Isolated Patterns | 381 | ||
| 10.2.6 Summary of Design Methodology | 383 | ||
| 10.2.7 Chemicals for Wet Anisotropic Etching | 385 | ||
| 10.3 Dry Etching and Deep Reactive Ion Etching | 390 | ||
| 10.4 Isotropic Wet Etching | 391 | ||
| 10.5 Gas Phase Etchants | 391 | ||
| 10.6 Native Oxide | 392 | ||
| 10.7 Special Wafers and Techniques | 393 | ||
| Summary | 393 | ||
| Problems | 394 | ||
| References | 400 | ||
| Chapter 11 Surface Micromachining | 403 | ||
| 11.0 Preview | 403 | ||
| 11.1 Basic Surface Micromachining Processes | 403 | ||
| 11.1.1 Sacrificial Etching Process | 403 | ||
| 11.1.2 Micro Motor Fabrication Process—A First Pass | 404 | ||
| 11.2.3 Micro Motor Fabrication Process—A Second Pass | 405 | ||
| 11.1.4 Micro Motor Fabrication Process—Third Pass | 406 | ||
| 11.2 Structural and Sacrificial Materials | 409 | ||
| 11.2.1 Material Selection Criteria for a Two-layer Process | 409 | ||
| 11.2.2 Thin Films by Low Pressure Chemical Vapor Deposition | 410 | ||
| 11.2.3 Other Surface Micromachining Materials and Processes | 413 | ||
| 11.3 Acceleration of Sacrificial Etch | 414 | ||
| 11.4 Stiction and Anti-stiction Methods | 416 | ||
| Summary | 417 | ||
| Problems | 418 | ||
| References | 420 | ||
| Chapter 12 Process Synthesis: Putting It All Together | 424 | ||
| 12.0 Preview | 424 | ||
| 12.1 Process for Suspension Beams | 426 | ||
| 12.2 Process for Membranes | 432 | ||
| 12.3 Process for Cantilevers | 437 | ||
| 12.3.1 SPM Technologies Case Motivation | 437 | ||
| 12.3.2 General Fabrication Methods for Tips | 439 | ||
| 12.3.3 Cantilevers with Integrated Tips | 441 | ||
| 12.3.4 Cantilevers with Integrated Sensors | 446 | ||
| 12.3.5 SPM Probes with Actuators | 452 | ||
| 12.4 Practical Factors Affecting Yield of MEMS | 457 | ||
| Summary | 458 | ||
| Problems | 458 | ||
| References | 462 | ||
| Chapter 13 Polymer MEMS | 465 | ||
| 13.0 Preview | 465 | ||
| 13.1 Introduction | 465 | ||
| 13.2 Polymers in MEMS | 467 | ||
| 13.2.1 Polyimide | 469 | ||
| 13.2.2 SU-8 | 469 | ||
| 13.2.3 Liquid Crystal Polymer (LCP) | 470 | ||
| 13.2.4 PDMS | 471 | ||
| 13.2.5 PMMA | 473 | ||
| 13.2.6 Parylene | 473 | ||
| 13.2.7 Fluorocarbon | 474 | ||
| 13.2.8 Other Polymers | 474 | ||
| 13.3 Representative Applications | 475 | ||
| 13.3.1 Acceleration Sensors | 475 | ||
| 13.3.2 Pressure Sensors | 477 | ||
| 13.3.3 Flow Sensors | 481 | ||
| 13.3.4 Tactile Sensors | 483 | ||
| Summary | 486 | ||
| Problems | 486 | ||
| References | 487 | ||
| Chapter 14 Micro Fluidics Applications | 491 | ||
| 14.0 Preview | 491 | ||
| 14.1 Motivation for Microfluidics | 491 | ||
| 14.2 Essential Biology Concepts | 492 | ||
| 14.3 Basic Fluid Mechanics Concepts | 495 | ||
| 14.3.1 The Reynolds Number and Viscosity | 495 | ||
| 14.3.2 Methods for Fluid Movement in Channels | 497 | ||
| 14.3.3 Pressure Driven Flow | 497 | ||
| 14.3.4 Electrokinetic Flow | 500 | ||
| 14.3.5 Electrophoresis and Dielectrophoresis | 501 | ||
| 14.4 Design and Fabrication of Selective Components | 503 | ||
| 14.4.1 Channels | 503 | ||
| 14.4.2 Valves | 515 | ||
| Summary | 518 | ||
| Problems | 518 | ||
| References | 520 | ||
| Chapter 15 Case Studies of Selected MEMS Products | 525 | ||
| 15.0 Preview | 525 | ||
| 15.1 Case Studies: Blood Pressure (BP) Sensor | 526 | ||
| 15.1.1 Background and History | 526 | ||
| 15.1.2 Device Design Considerations | 527 | ||
| 15.1.3 Commercial Case: NovaSensor BP Sensor | 528 | ||
| 15.2 Case Studies: Microphone | 530 | ||
| 15.2.1 Background and History | 530 | ||
| 15.2.2 Design Considerations | 531 | ||
| 15.2.3 Commercial Case: Knowles Microphone | 532 | ||
| 15.3 Case Studies: Acceleration Sensors | 533 | ||
| 15.3.1 Background and History | 533 | ||
| 15.3.2 Design Considerations | 533 | ||
| 15.3.3 Commercial Case: Analog Devices and MEMSIC | 537 | ||
| 15.4 Case Studies: Gyros | 538 | ||
| 15.4.1 Background and History | 538 | ||
| 15.4.2 The Coriolis Force | 538 | ||
| 15.4.3 MEMS Gyro Design | 540 | ||
| 15.4.4 Single Axis Gyro Dynamics | 542 | ||
| 15.4.5 Commercial Case: InvenSense Gyro | 544 | ||
| 15.5 Summary of Top Concerns for MEMS Product Development | 545 | ||
| 15.5.1 Performance and Accuracy | 546 | ||
| 15.5.2 Repeatability and Reliability | 546 | ||
| 15.5.3 Managing the Cost of MEMS Products | 547 | ||
| 15.5.4 Market Uncertainties, Investment, and Competition | 547 | ||
| Summary | 548 | ||
| Problems | 548 | ||
| References | 552 | ||
| Appendix 1 Characteristics of Selected MEMS Materials | 553 | ||
| Appendix 2 Frequently Used Formula for Beams, Cantilevers, and Plates | 556 | ||
| Appendix 3 Basic Tools for Dealing with a Mechanical Second-order Dynamic System | 558 | ||
| Appendix 4 Most Commonly Encountered Materials | 562 | ||
| Appendix 5 Most Commonly Encountered Material Removal Process Steps | 563 | ||
| Appendix 6 A List of General Compatibility between General Materials and Processes | 564 | ||
| Appendix 7 Comparison of Commercial Inertial Sensors | 567 | ||
| Answers to Selected Problems | 569 | ||
| Index | 571 | ||
| A | 571 | ||
| B | 571 | ||
| C | 571 | ||
| D | 572 | ||
| E | 572 | ||
| F | 572 | ||
| G | 572 | ||
| H | 572 | ||
| I | 573 | ||
| J | 573 | ||
| K | 573 | ||
| L | 573 | ||
| M | 573 | ||
| N | 574 | ||
| O | 574 | ||
| P | 574 | ||
| Q | 575 | ||
| R | 575 | ||
| S | 575 | ||
| T | 576 | ||
| U | 576 | ||
| V | 576 | ||
| W | 576 | ||
| Y | 576 | ||
| Z | 576 |