MEMS and Microsystems

Tai-Ran Hsu, PhD, is a Professor in the Department of Mechanical and Aerospace Engineering, San Jose State University, California. Dr. Hsu is the author of the earlier edition of this book, which is considered one of the bestselling textbooks on the subject of MEMS.

• Preface xviiPreface To The First Edition xixSuggestions To Instructors xxiii1 OVERVIEW OF MEMS AND MICROSYSTEMS 11.1 MEMS and Microsystems 11.2 Typical MEMS and Microsystems Products 71.2.1 Microgears 71.2.2 Micromotors 71.2.3 Microturbines 71.2.4 Micro-Optical Components 71.3 Evolution of Microfabrication 101.4 Microsystems and Microelectronics 111.5 Multidisciplinary Nature of Microsystems Design and Manufacture 131.6 Microsystems and Miniaturization 151.7 Application of Microsystems in Automotive Industry 211.7.1 Safety 221.7.2 Engine and Power Trains 241.7.3 Comfort and Convenience 241.7.4 Vehicle Diagnostics and Health Monitoring 241.7.5 Future Automotive Applications 261.8 Application of Microsystems in Other Industries 271.8.1 Application in Health Care Industry 271.8.2 Application in Aerospace Industry 281.8.3 Application in Industrial Products 291.8.4 Application in Consumer Products 291.8.5 Application in Telecommunications 301.9 Markets for Microsystems 30Problems 322 WORKING PRINCIPLES OF MICROSYSTEMS 352.1 Introduction 352.2 Microsensors 352.2.1 Acoustic Wave Sensors 362.2.2 Biomedical and Biosensors 372.2.3 Chemical Sensors 402.2.4 Optical Sensors 422.2.5 Pressure Sensors 442.2.6 Thermal Sensors 502.3 Microactuation 532.3.1 Actuation Using Thermal Forces 532.3.2 Actuation Using Shape Memory Alloys 542.3.3 Actuation Using Piezoelectric Effect 542.3.4 Actuation Using Electrostatic Forces 552.4 MEMS with Microactuators 592.4.1 Microgrippers 592.4.2 Miniature Microphones 612.4.3 Micromotors 642.5 Microactuators with Mechanical Inertia 662.5.1 Microaccelerometers 662.5.2 Microgyroscopes 702.6 Microfluidics 722.6.1 Microvalves 742.6.2 Micropumps 752.6.3 Micro–Heat Pipes 75Problems 773 ENGINEERING SCIENCE FOR MICROSYSTEMS DESIGN AND FABRICATION 833.1 Introduction 833.2 Atomic Structure of Matter 833.3 Ions and Ionization 863.4 Molecular Theory of Matter and Intermolecular Forces 873.5 Doping of Semiconductors 893.6 Diffusion Process 923.7 Plasma Physics 993.8 Electrochemistry 1003.8.1 Electrolysis 1013.8.2 Electrohydrodynamics 102Problems 1054 ENGINEERING MECHANICS FOR MICROSYSTEMS DESIGN 1094.1 Introduction 1094.2 Static Bending of Thin Plates 1104.2.1 Bending of Circular Plates with Edge Fixed 1124.2.2 Bending of Rectangular Plates with All Edges Fixed 1144.2.3 Bending of Square Plates with Edges Fixed 1164.3 Mechanical Vibration 1194.3.1 General Formulation 1194.3.2 Resonant Vibration 1234.3.3 Microaccelerometers 1254.3.4 Design Theory of Accelerometers 1264.3.5 Damping Coefficients 1344.3.6 Resonant Microsensors 1444.4 Thermomechanics 1504.4.1 Thermal Effects on Mechanical Strength of Materials 1504.4.2 Creep Deformation 1504.4.3 Thermal Stresses 1524.5 Fracture Mechanics 1654.5.1 Stress Intensity Factors 1664.5.2 Fracture Toughness 1674.5.3 Interfacial Fracture Mechanics 1694.6 Thin-Film Mechanics 1724.7 Overview of Finite Element Stress Analysis 1734.7.1 The Principle 1734.7.2 Engineering Applications 1754.7.3 Input Information to FEA 1754.7.4 Output from FEA 1754.7.5 Graphical Output 1764.7.6 General Remarks 176Problems 1785 THERMOFLUID ENGINEERING AND MICROSYSTEMS DESIGN 1835.1 Introduction 1835.2 Overview of Basics of Fluid Mechanics at Macro- and Mesoscales 1845.2.1 Viscosity of Fluids 1845.2.2 Streamlines and Stream Tubes 1865.2.3 Control Volumes and Control Surfaces 1875.2.4 Flow Patterns and Reynolds Number 1875.3 Basic Equations in Continuum Fluid Dynamics 1875.3.1 Continuity Equation 1875.3.2 Momentum Equation 1905.3.3 Equation of Motion 1925.4 Laminar Fluid Flow in Circular Conduits 1955.5 Computational Fluid Dynamics 1985.6 Incompressible Fluid Flow in Microconduits 1995.6.1 Surface Tension 1995.6.2 Capillary Effect 2015.6.3 Micropumping 2035.7 Overview of Heat Conduction in Solids 2045.7.1 General Principle of Heat Conduction 2045.7.2 Fourier Law of Heat Conduction 2055.7.3 Heat Conduction Equation 2075.7.4 Newton’s Cooling Law 2085.7.5 Solid–Fluid Interaction 2095.7.6 Boundary Conditions 2105.8 Heat Conduction in Multilayered Thin Films 2155.9 Heat Conduction in Solids at Submicrometer Scale 220Problems 2216 SCALING LAWS IN MINIATURIZATION 2276.1 Introduction to Scaling 2276.2 Scaling in Geometry 2286.3 Scaling in Rigid-Body Dynamics 2306.3.1 Scaling in Dynamic Forces 2306.3.2 Trimmer Force Scaling Vector 2316.4 Scaling in Electrostatic Forces 2336.5 Scaling of Electromagnetic Forces 2356.6 Scaling in Electricity 2376.7 Scaling in Fluid Mechanics 2386.8 Scaling in Heat Transfer 2426.8.1 Scaling in Heat Conduction 2426.8.2 Scaling in Heat Convection 243Problems 2447 MATERIALS FOR MEMS AND MICROSYSTEMS 2457.1 Introduction 2457.2 Substrates and Wafers 2457.3 Active Substrate Materials 2477.4 Silicon as Substrate Material 2477.4.1 Ideal Substrate for MEMS 2477.4.2 Single-Crystal Silicon and Wafers 2487.4.3 Crystal Structure 2507.4.4 Miller Indices 2537.4.5 Mechanical Properties of Silicon 2567.5 Silicon Compounds 2587.5.1 Silicon Dioxide 2587.5.2 Silicon Carbide 2597.5.3 Silicon Nitride 2597.5.4 Polycrystalline Silicon 2607.6 Silicon Piezoresistors 2617.7 Gallium Arsenide 2667.8 Quartz 2677.9 Piezoelectric Crystals 2687.10 Polymers 2747.10.1 Polymers as Industrial Materials 2747.10.2 Polymers for MEMS and Microsystems 2757.10.3 Conductive Polymers 2757.10.4 Langmuir–Blodgett Film 2777.10.5 SU-8 Photoresists 2787.11 Packaging Materials 280Problems 281 8 MICROSYSTEMS FABRICATION PROCESSES 2858.1 Introduction 2858.2 Photolithography 2858.2.1 Overview 2868.2.2 Photoresists and Application 2868.2.3 Light Sources 2888.2.4 Photoresist Development 2898.2.5 Photoresist Removal and Postbaking 2898.3 Ion Implantation 2898.4 Diffusion 2928.5 Oxidation 2958.5.1 Thermal Oxidation 2958.5.2 Silicon Dioxide 2968.5.3 Thermal Oxidation Rates 2968.5.4 Oxide Thickness by Color 3008.6 Chemical Vapor Deposition 3018.6.1 Working Principle of CVD 3018.6.2 Chemical Reactions in CVD 3028.6.3 Rate of Deposition 3038.6.4 Enhanced CVD 3108.7 Physical Vapor Deposition: Sputtering 3128.8 Deposition by Epitaxy 3138.9 Etching 3158.9.1 Chemical Etching 3168.9.2 Plasma Etching 3178.10 Summary of Microfabrication 317Problems 3189 OVERVIEW OF MICROMANUFACTURING 3239.1 Introduction 3239.2 Bulk Micromanufacturing 3249.2.1 Overview of Etching 3249.2.2 Isotropic and Anisotropic Etching 3259.2.3 Wet Etchants 3269.2.4 Etch Stop 3289.2.5 Dry Etching 3299.2.6 Comparison of Wet versus Dry Etching 3339.3 Surface Micromachining 3339.3.1 Description 3339.3.2 Process 3359.3.3 Mechanical Problems Associated with Surface Micromachining 3369.4 LIGA Process 3389.4.1 Description 3399.4.2 Materials for Substrates and Photoresists 3409.4.3 Electroplating 3419.4.4 SLIGA Process 3429.5 Summary of Micromanufacturing 3439.5.1 Bulk Micromanufacturing 3439.5.2 Surface Micromachining 3439.5.3 LIGA Process 343Problems 34410 MICROSYSTEMS DESIGN 34910.1 Introduction 34910.2 Design Considerations 35010.2.1 Design Constraints 35110.2.2 Selection of Materials 35210.2.3 Selection of Manufacturing Processes 35410.2.4 Selection of Signal Transduction 35510.2.5 Electromechanical System 35810.2.6 Packaging 35810.3 Process Design 35810.3.1 Photolithography 35910.3.2 Thin-Film Fabrications 36010.3.3 Geometry Shaping 36210.4 Mechanical Design 36210.4.1 Geometry of MEMS Components 36210.4.2 Thermomechanical Loading 36210.4.3 Thermomechanical Stress Analysis 36310.4.4 Dynamic Analysis 36410.4.5 Interfacial Fracture Analysis 36910.5 Mechanical Design Using Finite Element Method 36910.5.1 Finite Element Formulation 37010.5.2 Simulation of Microfabrication Processes 37510.6 Design of Silicon Die of a Micropressure Sensor 37810.7 Design of Microfluidic Network Systems 38210.7.1 Fluid Resistance in Microchannels 38310.7.2 Capillary Electrophoresis Network Systems 38610.7.3 Mathematical Modeling of Capillary Electrophoresis Network Systems 38810.7.4 Design Case: Capillary Electrophoresis Network System 38910.7.5 Capillary Electrophoresis in Curved Channels 39210.7.6 Issues in Design of CE Processes 39410.8 Computer-Aided Design 39510.8.1 Why CAD? 39510.8.2 What Is in a CAD Package for Microsystems? 39510.8.3 How to Choose a CAD Package 39810.8.4 Design Case Using CAD 398Problems 40211 ASSEMBLY, PACKAGING, AND TESTING OF MICROSYSTEMS 40711.1 Introduction 40711.2 Overview of Microassembly 40911.3 High Costs of Microassembly 41011.4 Microassembly Processes 41111.5 Major Technical Problems in Microassembly 41311.5.1 Tolerances in Microassembly 41411.5.2 Tools and Fixtures 41711.5.3 Contact Problems in Microassembly Tools 41711.6 Microassembly Work Cells 41911.7 Challenging Issues in Microassembly 42111.8 Overview of Microsystems Packaging 42211.9 General Considerations in Packaging Design 42411.10 Three Levels of Microsystems Packaging 42411.10.1 Die-Level Packaging 42411.10.2 Device-Level Packaging 42511.10.3 System-Level Packaging 42711.11 Interfaces in Microsystems Packaging 42711.12 Essential Packaging Technologies 42811.13 Die Preparation 42911.14 Surface Bonding 42911.14.1 Adhesives 43011.14.2 Eutectic Bonding 43111.14.3 Anodic Bonding 43211.14.4 Silicon Fusion Bonding 43411.14.5 Overview of Surface Bonding Techniques 43411.14.6 Silicon-on-Insulator: Special Surface Bonding Techniques 43511.15 Wire Bonding 43711.16 Sealing and Encapsulation 43911.16.1 Integrated Encapsulation Processes 44011.16.2 Sealing by Wafer Bonding 44111.16.3 Vacuum Sealing and Encapsulation 44211.17 Three-Dimensional Packaging 44311.18 Selection of Packaging Materials 44411.19 Signal Mapping and Transduction 44711.19.1 Typical Electrical Signals in Microsystems 44711.19.2 Measurement of Resistance 44711.19.3 Signal Mapping and Transduction in Pressure Sensors 44811.19.4 Capacitance Measurements 45011.20 Design Case on Pressure Sensor Packaging 45111.21 Reliability in MEMS Packaging 45511.22 Testing for Reliability 456Problems 45812 INTRODUCTION TO NANOSCALE ENGINEERING 46512.1 Introduction 46512.2 Micro- and Nanoscale Technologies 46712.3 General Principle of Nanofabrication 46812.4 Nanoproducts 47112.5 Application of Nanoproducts 47412.6 Quantum Physics 47812.7 Molecular Dynamics 47912.8 Fluid Flow in Submicrometer- and Nanoscales 48212.8.1 Rarefied Gas 48212.8.2 Knudsen and Mach Numbers 48212.8.3 Modeling of Micro- and Nanoscale Gas Flow 48312.9 Heat Conduction at Nanoscale 48612.9.1 Heat Transmission at Submicrometer- and Nanoscale 48612.9.2 Thermal Conductivity of Thin Films 48912.9.3 Heat Conduction Equation for Thin Films 49012.10 Measurement of Thermal Conductivity 49112.11 Challenges in Nanoscale Engineering 49712.11.1 Nanopatterning in Nanofabrication 49812.11.2 Nanoassembly 50012.11.3 New Materials for Nanoelectromechanical Systems (NEMS) 50012.11.4 Analytical Modeling 50112.11.5 Testing 50212.12 Social Impacts of Nanoscale Engineering 502Problems 503References 509Appendix 1 Recommended Units For Thermophysical Quantities 523Appendix 2 Conversion Of Units 525Index 527