Introductory MEMS: Fabrication and Applications / Edition 1

by Thomas M. Adams, Richard A. Layton

Overview

Introductory MEMS: Fabrication and Applications is a practical introduction to MEMS for advanced undergraduate and graduate students. Part I introduces the student to the most commonly used MEMS fabrication techniques as well as the MEMS devices produced using these techniques. Part II focuses on MEMS transducers: principles of operation, modeling from first principles, and a detailed look at commercialized MEMS devices, in addition to microfluidics. Multiple field-tested laboratory exercises are included, designed to facilitate student learning about the fundamentals of microfabrication processes. References, suggested reading, review questions, and homework problems are provided at the close of each chapter.

Introductory MEMS: Fabrication and Applications is an excellent introduction to the subject, with a tested pedagogical structure and an accessible writing style suitable for students at an advanced undergraduate level across academic disciplines.

Product Details

ISBN-13:	9780387095103
Publisher:	Springer US
Publication date:	12/21/2009
Series:	Lecture Notes in Computer Science Series
Edition description:	2010
Pages:	440
Product dimensions:	6.30(w) x 9.30(h) x 1.30(d)

Table of Contents

Preface xiii

Part I Fabrication

Chapter 1 Introduction 3

1.1 What are MEMS? 3

1.2 Why MEMS? 4

1.2.1 Low cost, redundancy and disposability 4

1.2.2 Favorable scalings 5

1.3 How are MEMS made? 8

1.4 Roadmap and perspective 12

Essay: The Role of Surface to Volume Atoms as Magnetic Devices Miniaturize 12

Chapter 2 The substrate and adding material to it 17

2.1 Introduction 17

2.2 The silicon substrate 17

2.2.1 Silicon growth 17

2.2.2 It's a crystal 19

2.2.3 Miller indices 20

2.2.4 It's a semiconductor 24

2.3 Additive technique: Oxidation 35

2.3.1 Growing an oxide layer 35

2.3.2 Oxidation kinetics 37

2.4 Additive technique: Physical vapor deposition 40

2.4.1 Vacuum fundamentals 41

2.4.2 Thermal evaporation 46

2.4.3 Sputtering 51

2.5 Other additive techniques 57

2.5.1 Chemical vapor deposition 57

2.5.2 Electrodeposition 58

2.5.3 Spin casting 58

2.5.4 Wafer bonding 58

Essay: Silicon Ingot Manufacturing 59

Chapter 3 Creating and transferring patterns-Photolithography 65

3.1 Introduction 65

3.2 Keeping it clean 66

3.3 Photoresist 69

3.3.1 Positive resist 69

3.3.2 Negative resist 70

3.4 Working with resist 71

3.4.1 Applying photoresist 71

3.4.2 Exposure and pattern transfer 72

3.4.3 Development and post-treatment 77

3.5 Masks 79

3.6 Resolution 81

3.6.1 Resolution in contact and proximity printing 81

3.6.2 Resolution in projection printing 82

3.6.3 Sensitivity and resist profiles 84

3.6.4 Modeling of resist profiles 86

3.6.5 Photolithography resolution enhancement technology 87

3.6.6 Mask alignment 88

3.7 Permanent resists 89

Essay: Photolithography-Past, Present and Future 90

Chapter 4 Creating structures-Micromachining 95

4.1 Introduction 95

4.2 Bulk micromachining processes 96

4.2.1 Wet chemical etching 96

4.2.2 Dry etching 106

4.3 Surface micromachining 108

4.3.1 Surface micromachining processes 109

4.3.2 Problems with surface micromachining 111

4.3.3 Lift-off 112

4.4 Process integration 113

4.4.1 A surface micromachining example 115

4.4.2 Designing a good MEMS process flow 119

4.4.3 Last thoughts 124

Essay: Introduction to MEMS Packaging 126

Chapter 5 Solid mechanics 131

5.1 Introduction 131

5.2 Fundamentals of solid mechanics 131

5.2.1 Stress 132

5.2.2 Strain 133

5.2.3 Elasticity 135

5.2.4 Special cases 138

5.2.5 Non-isotropic materials 139

5.2.6 Thermal strain 141

5.3 Properties of thin films 142

5.3.1 Adhesion 142

5.3.2 Stress in thin films 142

5.3.3 Peel forces 149

Part II Applications

Chapter 6 Thinking about modeling 157

6.1 What is modeling? 157

6.2 Units 158

6.3 The input-output concept 159

6.4 Physical variables and notation 162

6.5 Preface to the modeling chapters 163

Chapter 7 MEMS transducers-An overview of how they work 167

7.1 What is a transducer? 167

7.2 Distinguishing between sensors and actuators 168

7.3 Response characteristics of transducers 171

7.3.1 Static response characteristics 172

7.3.2 Dynamic performance characteristics 173

7.4 MEMS sensors: principles of operation 178

7.4.1 Resistive sensing 178

7.4.2 Capacitive sensing 181

7.4.3 Piezoelectric sensing 182

7.4.4 Resonant sensing 184

7.4.5 Thermoelectric sensing 186

7.4.6 Magnetic sensing 189

7.5 MEMS actuators: principles of operation 193

7.5.1 Capacitive actuation 193

7.5.2 Piezoelectric actuation 194

7.5.3 Thermo-mechanical actuation 196

7.5.4 Thermo-electric cooling 201

7.5.5 Magnetic actuation 202

7.6 Signal conditioning 204

7.7 A quick look at two applications 206

7.7.1 RF applications 207

7.7.2 Optical applications 207

Chapter 8 Piezoresistive transducers 211

8.1 Introduction 211

8.2 Modeling piezoresistive transducers 212

8.2.1 Bridge analysis 213

8.2.2 Relating electrical resistance to mechanical strain 215

8.3 Device case study: Piezoresistive pressure sensor 221

Chapter 9 Capacitive transducers 231

9.1 Introduction 231

9.2 Capacitor fundamentals 232

9.2.1 Fixed-capacitance capacitor 232

9.2.2 Variable-capacitance capacitor 234

9.2.3 An overview of capacitive sensors and actuators 236

9.3 Modeling a capacitive sensor 239

9.3.1 Capacitive half-bridge 239

9.3.2 Conditioning the signal from the half-bridge 243

9.3.3 Mechanical subsystem 246

9.4 Device case study: Capacitive accelerometer 250

Chapter 10 Piezoelectric transducers 255

10.1 Introduction 255

10.2 Modeling piezoelectric materials 256

10.3 Mechanical modeling of beams and plates 261

10.3.1 Distributed parameter modeling 261

10.3.2 Statics 262

10.3.3 Bending in beams 268

10.3.4 Bending in plates 274

10.4 Case study: Cantilever piezoelectric actuator 276

Chapter 11 Thermal transducers 283

11.1 Introduction 283

11.2 Basic heat transfer 284

11.2.1 Conduction 286

11.2.2 Convection 288

11.2.3 Radiation 289

11.3 Case study: Hot-arm actuator 294

11.3.1 Lumped element model 295

11.3.2 Distributed parameter model 300

11.3.3 FEA model 306

Essay: Effect of Scale on Thermal Properties 310

Chapter 12 Introduction to microfluidics 317

12.1 Introduction 317

12.2 Basics of fluid mechanics 319

12.2.1 Viscosity and flow regimes 320

12.2.2 Entrance lengths 324

12.3 Basic equations of fluid mechanics 325

12.3.1 Conservation of mass 325

12.3.2 Conservation of linear momentum 326

12.3.3 Conservation equations at a point: Continuity and Navier-Stokes equations 329

12.4 Some solutions to the Navier-Stokes equations 337

12.4.1 Couette flow 337

12.4.2 Poiseuille flow 339

12.5 Electro-osmotic flow 339

12.5.1 Electrostatics 340

12.5.2 Ionic double layers 346

12.5.3 Navier-Stokes with a constant electric field 355

12.6 Electrophoretic separation 357

Essay: Detection Schemes Employed in Microfluidic Devices for Chemical Analysis 362

Part III Microfabrication laboratories

Chapter 13 Microfabrication laboratories 371

13.1 Hot-arm actuator as a hands-on case study 371

13.2 Overview of fabrication of hot-arm actuators 372

13.3 Cleanroom safety and etiquette 375

13.4 Experiments 377

Experiment 1 Wet oxidation of a silicon wafer 377

Experiment 2 Photolithography of sacrificial layer 384

Experiment 3 Depositing metal contacts with evaporation 388

Experiment 4 Wet chemical etching of aluminum 392

Experiment 5 Plasma ash release 395

Experiment 6 Characterization of hot-arm actuators 397

Appendix A Notation 405

Appendix B Periodic table of the elements 411

Appendix C The complimentary error function 413

Appendix D Color chart for thermally grown silicon dioxide 415

Glossary 417

Subject Index 439