Introductory MEMS

by Adams, Thomas M.; Layton, Richard A.

• ISBN13: 9780387095103
• ISBN10: 0387095101
• Format: Hardcover
• Copyright: 2010-01-12
• Publisher: Springer Verlag

Summary

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.

Table of Contents

Preface	p. xiii
Fabrication
Introduction	p. 3
What are MEMS?	p. 3
Why MEMS?	p. 4
Low cost, redundancy and disposability	p. 4
Favorable scalings	p. 5
How are MEMS made?	p. 8
Roadmap and perspective	p. 12
Essay: The Role of Surface to Volume Atoms as Magnetic Devices Miniaturize	p. 12
The substrate and adding material to it	p. 17
Introduction	p. 17
The silicon substrate	p. 17
Silicon growth	p. 17
It's a crystal	p. 19
Miller indices	p. 20
It's a semiconductor	p. 24
Additive technique: Oxidation	p. 35
Growing an oxide layer	p. 35
Oxidation kinetics	p. 37
Additive technique: Physical vapor deposition	p. 40
Vacuum fundamentals	p. 41
Thermal evaporation	p. 46
Sputtering	p. 51
Other additive techniques	p. 57
Chemical vapor deposition	p. 57
Electrodeposition	p. 58
Spin casting	p. 58
Wafer bonding	p. 58
Essay: Silicon Ingot Manufacturing	p. 59
Creating and transferring patterns-Photolithography	p. 65
Introduction	p. 65
Keeping it clean	p. 66
Photoresist	p. 69
Positive resist	p. 69
Negative resist	p. 70
Working with resist	p. 71
Applying photoresist	p. 71
Exposure and pattern transfer	p. 72
Development and post-treatment	p. 77
Masks	p. 79
Resolution	p. 81
Resolution in contact and proximity printing	p. 81
Resolution in projection printing	p. 82
Sensitivity and resist profiles	p. 84
Modeling of resist profiles	p. 86
Photolithography resolution enhancement technology	p. 87
Mask alignment	p. 88
Permanent resists	p. 89
Essay: Photolithography-Past, Present and Future	p. 90
Creating structures-Micromachining	p. 95
Introduction	p. 95
Bulk micromachining processes	p. 96
Wet chemical etching	p. 96
Dry etching	p. 106
Surface micromachining	p. 108
Surface micromachining processes	p. 109
Problems with surface micromachining	p. 111
Lift-off	p. 112
Process integration	p. 113
A surface micromachining example	p. 115
Designing a good MEMS process flow	p. 119
Last thoughts	p. 124
Essay: Introduction to MEMS Packaging	p. 126
Solid mechanics	p. 131
Introduction	p. 131
Fundamentals of solid mechanics	p. 131
Stress	p. 132
Strain	p. 133
Elasticity	p. 135
Special cases	p. 138
Non-isotropic materials	p. 139
Thermal strain	p. 141
Properties of thin films	p. 142
Adhesion	p. 142
Stress in thin films	p. 142
Peel forces	p. 149
Applications
Thinking about modeling	p. 157
What is modeling?	p. 157
Units	p. 158
The input-output concept	p. 159
Physical variables and notation	p. 162
Preface to the modeling chapters	p. 163
MEMS transducers-An overview of how they work	p. 167
What is a transducer?	p. 167
Distinguishing between sensors and actuators	p. 168
Response characteristics of transducers	p. 171
Static response characteristics	p. 172
Dynamic performance characteristics	p. 173
MEMS sensors: principles of operation	p. 178
Resistive sensing	p. 178
Capacitive sensing	p. 181
Piezoelectric sensing	p. 182
Resonant sensing	p. 184
Thermoelectric sensing	p. 186
Magnetic sensing	p. 189
MEMS actuators: principles of operation	p. 193
Capacitive actuation	p. 193
Piezoelectric actuation	p. 194
Thermo-mechanical actuation	p. 196
Thermo-electric cooling	p. 201
Magnetic actuation	p. 202
Signal conditioning	p. 204
A quick look at two applications	p. 206
RF applications	p. 207
Optical applications	p. 207
Piezoresistive transducers	p. 211
Introduction	p. 211
Modeling piezoresistive transducers	p. 212
Bridge analysis	p. 213
Relating electrical resistance to mechanical strain	p. 215
Device case study: Piezoresistive pressure sensor	p. 221
Capacitive transducers	p. 231
Introduction	p. 231
Capacitor fundamentals	p. 232
Fixed-capacitance capacitor	p. 232
Variable-capacitance capacitor	p. 234
An overview of capacitive sensors and actuators	p. 236
Modeling a capacitive sensor	p. 239
Capacitive half-bridge	p. 239
Conditioning the signal from the half-bridge	p. 243
Mechanical subsystem	p. 246
Device case study: Capacitive accelerometer	p. 250
Piezoelectric transducers	p. 255
Introduction	p. 255
Modeling piezoelectric materials	p. 256
Mechanical modeling of beams and plates	p. 261
Distributed parameter modeling	p. 261
Statics	p. 262
Bending in beams	p. 268
Bending in plates	p. 274
Case study: Cantilever piezoelectric actuator	p. 276
Thermal transducers	p. 283
Introduction	p. 283
Basic heat transfer	p. 284
Conduction	p. 286
Convection	p. 288
Radiation	p. 289
Case study: Hot-arm actuator	p. 294
Lumped element model	p. 295
Distributed parameter model	p. 300
FEA model	p. 306
Essay: Effect of Scale on Thermal Properties	p. 310
Introduction to microfluidics	p. 317
Introduction	p. 317
Basics of fluid mechanics	p. 319
Viscosity and flow regimes	p. 320
Entrance lengths	p. 324
Basic equations of fluid mechanics	p. 325
Conservation of mass	p. 325
Conservation of linear momentum	p. 326
Conservation equations at a point: Continuity and Navier-Stokes equations	p. 329
Some solutions to the Navier-Stokes equations	p. 337
Couette flow	p. 337
Poiseuille flow	p. 339
Electro-osmotic flow	p. 339
Electrostatics	p. 340
Ionic double layers	p. 346
Navier-Stokes with a constant electric field	p. 355
Electrophoretic separation	p. 357
Essay: Detection Schemes Employed in Microfluidic Devices for Chemical Analysis	p. 362
Microfabrication laboratories
Microfabrication laboratories	p. 371
Hot-arm actuator as a hands-on case study	p. 371
Overview of fabrication of hot-arm actuators	p. 372
Cleanroom safety and etiquette	p. 375
Experiments	p. 377
Wet oxidation of a silicon wafer	p. 377
Photolithography of sacrificial layer	p. 384
Depositing metal contacts with evaporation	p. 388
Wet chemical etching of aluminum	p. 392
Plasma ash release	p. 395
Characterization of hot-arm actuators	p. 397
Notation	p. 405
Periodic table of the elements	p. 411
The complimentary error function	p. 413
Color chart for thermally grown silicon dioxide	p. 415
Glossary	p. 417
Subject Index	p. 439
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