MEMS and Microsystems: Design, Manufacture, and Nanoscale Engineering, 2nd Edition

Preface xvii

Preface To The First Edition xix

Suggestions To Instructors xxiii

1 OVERVIEW OF MEMS AND MICROSYSTEMS 1

1.1 MEMS and Microsystems 1

1.2 Typical MEMS and Microsystems Products 7

1.2.1 Microgears 7

1.2.2 Micromotors 7

1.2.3 Microturbines 7

1.2.4 Micro-Optical Components 7

1.3 Evolution of Microfabrication 10

1.4 Microsystems and Microelectronics 11

1.5 Multidisciplinary Nature of Microsystems Design and Manufacture 13

1.6 Microsystems and Miniaturization 15

1.7 Application of Microsystems in Automotive Industry 21

1.7.1 Safety 22

1.7.2 Engine and Power Trains 24

1.7.3 Comfort and Convenience 24

1.7.4 Vehicle Diagnostics and Health Monitoring 24

1.7.5 Future Automotive Applications 26

1.8 Application of Microsystems in Other Industries 27

1.8.1 Application in Health Care Industry 27

1.8.2 Application in Aerospace Industry 28

1.8.3 Application in Industrial Products 29

1.8.4 Application in Consumer Products 29

1.8.5 Application in Telecommunications 30

1.9 Markets for Microsystems 30

Problems 32

2 WORKING PRINCIPLES OF MICROSYSTEMS 35

2.1 Introduction 35

2.2 Microsensors 35

2.2.1 Acoustic Wave Sensors 36

2.2.2 Biomedical and Biosensors 37

2.2.3 Chemical Sensors 40

2.2.4 Optical Sensors 42

2.2.5 Pressure Sensors 44

2.2.6 Thermal Sensors 50

2.3 Microactuation 53

2.3.1 Actuation Using Thermal Forces 53

2.3.2 Actuation Using Shape Memory Alloys 54

2.3.3 Actuation Using Piezoelectric Effect 54

2.3.4 Actuation Using Electrostatic Forces 55

2.4 MEMS with Microactuators 59

2.4.1 Microgrippers 59

2.4.2 Miniature Microphones 61

2.4.3 Micromotors 64

2.5 Microactuators with Mechanical Inertia 66

2.5.1 Microaccelerometers 66

2.5.2 Microgyroscopes 70

2.6 Microfluidics 72

2.6.1 Microvalves 74

2.6.2 Micropumps 75

2.6.3 Micro–Heat Pipes 75

Problems 77

3 ENGINEERING SCIENCE FOR MICROSYSTEMS DESIGN AND FABRICATION 83

3.1 Introduction 83

3.2 Atomic Structure of Matter 83

3.3 Ions and Ionization 86

3.4 Molecular Theory of Matter and Intermolecular Forces 87

3.5 Doping of Semiconductors 89

3.6 Diffusion Process 92

3.7 Plasma Physics 99

3.8 Electrochemistry 100

3.8.1 Electrolysis 101

3.8.2 Electrohydrodynamics 102

Problems 105

4 ENGINEERING MECHANICS FOR MICROSYSTEMS DESIGN 109

4.1 Introduction 109

4.2 Static Bending of Thin Plates 110

4.2.1 Bending of Circular Plates with Edge Fixed 112

4.2.2 Bending of Rectangular Plates with All Edges Fixed 114

4.2.3 Bending of Square Plates with Edges Fixed 116

4.3 Mechanical Vibration 119

4.3.1 General Formulation 119

4.3.2 Resonant Vibration 123

4.3.3 Microaccelerometers 125

4.3.4 Design Theory of Accelerometers 126

4.3.5 Damping Coefficients 134

4.3.6 Resonant Microsensors 144

4.4 Thermomechanics 150

4.4.1 Thermal Effects on Mechanical Strength of Materials 150

4.4.2 Creep Deformation 150

4.4.3 Thermal Stresses 152

4.5 Fracture Mechanics 165

4.5.1 Stress Intensity Factors 166

4.5.2 Fracture Toughness 167

4.5.3 Interfacial Fracture Mechanics 169

4.6 Thin-Film Mechanics 172

4.7 Overview of Finite Element Stress Analysis 173

4.7.1 The Principle 173

4.7.2 Engineering Applications 175

4.7.3 Input Information to FEA 175

4.7.4 Output from FEA 175

4.7.5 Graphical Output 176

4.7.6 General Remarks 176

Problems 178

5 THERMOFLUID ENGINEERING AND MICROSYSTEMS DESIGN 183

5.1 Introduction 183

5.2 Overview of Basics of Fluid Mechanics at Macro- and Mesoscales 184

5.2.1 Viscosity of Fluids 184

5.2.2 Streamlines and Stream Tubes 186

5.2.3 Control Volumes and Control Surfaces 187

5.2.4 Flow Patterns and Reynolds Number 187

5.3 Basic Equations in Continuum Fluid Dynamics 187

5.3.1 Continuity Equation 187

5.3.2 Momentum Equation 190

5.3.3 Equation of Motion 192

5.4 Laminar Fluid Flow in Circular Conduits 195

5.5 Computational Fluid Dynamics 198

5.6 Incompressible Fluid Flow in Microconduits 199

5.6.1 Surface Tension 199

5.6.2 Capillary Effect 201

5.6.3 Micropumping 203

5.7 Overview of Heat Conduction in Solids 204

5.7.1 General Principle of Heat Conduction 204

5.7.2 Fourier Law of Heat Conduction 205

5.7.3 Heat Conduction Equation 207

5.7.4 Newton’s Cooling Law 208

5.7.5 Solid–Fluid Interaction 209

5.7.6 Boundary Conditions 210

5.8 Heat Conduction in Multilayered Thin Films 215

5.9 Heat Conduction in Solids at Submicrometer Scale 220

Problems 221

6 SCALING LAWS IN MINIATURIZATION 227

6.1 Introduction to Scaling 227

6.2 Scaling in Geometry 228

6.3 Scaling in Rigid-Body Dynamics 230

6.3.1 Scaling in Dynamic Forces 230

6.3.2 Trimmer Force Scaling Vector 231

6.4 Scaling in Electrostatic Forces 233

6.5 Scaling of Electromagnetic Forces 235

6.6 Scaling in Electricity 237

6.7 Scaling in Fluid Mechanics 238

6.8 Scaling in Heat Transfer 242

6.8.1 Scaling in Heat Conduction 242

6.8.2 Scaling in Heat Convection 243

Problems 244

7 MATERIALS FOR MEMS AND MICROSYSTEMS 245

7.1 Introduction 245

7.2 Substrates and Wafers 245

7.3 Active Substrate Materials 247

7.4 Silicon as Substrate Material 247

7.4.1 Ideal Substrate for MEMS 247

7.4.2 Single-Crystal Silicon and Wafers 248

7.4.3 Crystal Structure 250

7.4.4 Miller Indices 253

7.4.5 Mechanical Properties of Silicon 256

7.5 Silicon Compounds 258

7.5.1 Silicon Dioxide 258

7.5.2 Silicon Carbide 259

7.5.3 Silicon Nitride 259

7.5.4 Polycrystalline Silicon 260

7.6 Silicon Piezoresistors 261

7.7 Gallium Arsenide 266

7.8 Quartz 267

7.9 Piezoelectric Crystals 268

7.10 Polymers 274

7.10.1 Polymers as Industrial Materials 274

7.10.2 Polymers for MEMS and Microsystems 275

7.10.3 Conductive Polymers 275

7.10.4 Langmuir–Blodgett Film 277

7.10.5 SU-8 Photoresists 278

7.11 Packaging Materials 280

Problems 281 

8 MICROSYSTEMS FABRICATION PROCESSES 285

8.1 Introduction 285

8.2 Photolithography 285

8.2.1 Overview 286

8.2.2 Photoresists and Application 286

8.2.3 Light Sources 288

8.2.4 Photoresist Development 289

8.2.5 Photoresist Removal and Postbaking 289

8.3 Ion Implantation 289

8.4 Diffusion 292

8.5 Oxidation 295

8.5.1 Thermal Oxidation 295

8.5.2 Silicon Dioxide 296

8.5.3 Thermal Oxidation Rates 296

8.5.4 Oxide Thickness by Color 300

8.6 Chemical Vapor Deposition 301

8.6.1 Working Principle of CVD 301

8.6.2 Chemical Reactions in CVD 302

8.6.3 Rate of Deposition 303

8.6.4 Enhanced CVD 310

8.7 Physical Vapor Deposition: Sputtering 312

8.8 Deposition by Epitaxy 313

8.9 Etching 315

8.9.1 Chemical Etching 316

8.9.2 Plasma Etching 317

8.10 Summary of Microfabrication 317

Problems 318

9 OVERVIEW OF MICROMANUFACTURING 323

9.1 Introduction 323

9.2 Bulk Micromanufacturing 324

9.2.1 Overview of Etching 324

9.2.2 Isotropic and Anisotropic Etching 325

9.2.3 Wet Etchants 326

9.2.4 Etch Stop 328

9.2.5 Dry Etching 329

9.2.6 Comparison of Wet versus Dry Etching 333

9.3 Surface Micromachining 333

9.3.1 Description 333

9.3.2 Process 335

9.3.3 Mechanical Problems Associated with Surface Micromachining 336

9.4 LIGA Process 338

9.4.1 Description 339

9.4.2 Materials for Substrates and Photoresists 340

9.4.3 Electroplating 341

9.4.4 SLIGA Process 342

9.5 Summary of Micromanufacturing 343

9.5.1 Bulk Micromanufacturing 343

9.5.2 Surface Micromachining 343

9.5.3 LIGA Process 343

Problems 344

10 MICROSYSTEMS DESIGN 349

10.1 Introduction 349

10.2 Design Considerations 350

10.2.1 Design Constraints 351

10.2.2 Selection of Materials 352

10.2.3 Selection of Manufacturing Processes 354

10.2.4 Selection of Signal Transduction 355

10.2.5 Electromechanical System 358

10.2.6 Packaging 358

10.3 Process Design 358

10.3.1 Photolithography 359

10.3.2 Thin-Film Fabrications 360

10.3.3 Geometry Shaping 362

10.4 Mechanical Design 362

10.4.1 Geometry of MEMS Components 362

10.4.2 Thermomechanical Loading 362

10.4.3 Thermomechanical Stress Analysis 363

10.4.4 Dynamic Analysis 364

10.4.5 Interfacial Fracture Analysis 369

10.5 Mechanical Design Using Finite Element Method 369

10.5.1 Finite Element Formulation 370

10.5.2 Simulation of Microfabrication Processes 375

10.6 Design of Silicon Die of a Micropressure Sensor 378

10.7 Design of Microfluidic Network Systems 382

10.7.1 Fluid Resistance in Microchannels 383

10.7.2 Capillary Electrophoresis Network Systems 386

10.7.3 Mathematical Modeling of Capillary Electrophoresis Network Systems 388

10.7.4 Design Case: Capillary Electrophoresis Network System 389

10.7.5 Capillary Electrophoresis in Curved Channels 392

10.7.6 Issues in Design of CE Processes 394

10.8 Computer-Aided Design 395

10.8.1 Why CAD? 395

10.8.2 What Is in a CAD Package for Microsystems? 395

10.8.3 How to Choose a CAD Package 398

10.8.4 Design Case Using CAD 398

Problems 402

11 ASSEMBLY, PACKAGING, AND TESTING OF MICROSYSTEMS 407

11.1 Introduction 407

11.2 Overview of Microassembly 409

11.3 High Costs of Microassembly 410

11.4 Microassembly Processes 411

11.5 Major Technical Problems in Microassembly 413

11.5.1 Tolerances in Microassembly 414

11.5.2 Tools and Fixtures 417

11.5.3 Contact Problems in Microassembly Tools 417

11.6 Microassembly Work Cells 419

11.7 Challenging Issues in Microassembly 421

11.8 Overview of Microsystems Packaging 422

11.9 General Considerations in Packaging Design 424

11.10 Three Levels of Microsystems Packaging 424

11.10.1 Die-Level Packaging 424

11.10.2 Device-Level Packaging 425

11.10.3 System-Level Packaging 427

11.11 Interfaces in Microsystems Packaging 427

11.12 Essential Packaging Technologies 428

11.13 Die Preparation 429

11.14 Surface Bonding 429

11.14.1 Adhesives 430

11.14.2 Eutectic Bonding 431

11.14.3 Anodic Bonding 432

11.14.4 Silicon Fusion Bonding 434

11.14.5 Overview of Surface Bonding Techniques 434

11.14.6 Silicon-on-Insulator: Special Surface Bonding Techniques 435

11.15 Wire Bonding 437

11.16 Sealing and Encapsulation 439

11.16.1 Integrated Encapsulation Processes 440

11.16.2 Sealing by Wafer Bonding 441

11.16.3 Vacuum Sealing and Encapsulation 442

11.17 Three-Dimensional Packaging 443

11.18 Selection of Packaging Materials 444

11.19 Signal Mapping and Transduction 447

11.19.1 Typical Electrical Signals in Microsystems 447

11.19.2 Measurement of Resistance 447

11.19.3 Signal Mapping and Transduction in Pressure Sensors 448

11.19.4 Capacitance Measurements 450

11.20 Design Case on Pressure Sensor Packaging 451

11.21 Reliability in MEMS Packaging 455

11.22 Testing for Reliability 456

Problems 458

12 INTRODUCTION TO NANOSCALE ENGINEERING 465

12.1 Introduction 465

12.2 Micro- and Nanoscale Technologies 467

12.3 General Principle of Nanofabrication 468

12.4 Nanoproducts 471

12.5 Application of Nanoproducts 474

12.6 Quantum Physics 478

12.7 Molecular Dynamics 479

12.8 Fluid Flow in Submicrometer- and Nanoscales 482

12.8.1 Rarefied Gas 482

12.8.2 Knudsen and Mach Numbers 482

12.8.3 Modeling of Micro- and Nanoscale Gas Flow 483

12.9 Heat Conduction at Nanoscale 486

12.9.1 Heat Transmission at Submicrometer- and Nanoscale 486

12.9.2 Thermal Conductivity of Thin Films 489

12.9.3 Heat Conduction Equation for Thin Films 490

12.10 Measurement of Thermal Conductivity 491

12.11 Challenges in Nanoscale Engineering 497

12.11.1 Nanopatterning in Nanofabrication 498

12.11.2 Nanoassembly 500

12.11.3 New Materials for Nanoelectromechanical Systems (NEMS) 500

12.11.4 Analytical Modeling 501

12.11.5 Testing 502

12.12 Social Impacts of Nanoscale Engineering 502

Problems 503

References 509

Appendix 1 Recommended Units For Thermophysical Quantities 523

Appendix 2 Conversion Of Units 525

Index 527