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MOEMS: Micro-Opto-Electro-Mechanical Systems
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Book Description

"This is a great compendium of fundamentals, research, and applications in the rapidly growing area of optical microsystems. Every engineer working on MOEMS should have this on his or her bookshelf." --Douglas R. Sparks, Ph.D., Executive Vice President, Integrated Sensing Systems Inc. (ISSYS)

This book introduces the exciting and fast-moving field of MOEMS to graduate students, scientists, and engineers by providing a foundation of both micro-optics and MEMS that will enable them to conduct future research in the field. Born from the relatively new fields of MEMS and micro-optics, MOEMS are proving to be an attractive and low-cost solution to a range of device problems requiring high optical functionality and high optical performance. MOEMS solutions include optical devices for telecommunication, sensing, and mobile systems such as v-grooves, gratings, shutters, scanners, filters, micromirrors, switches, alignment aids, lens arrays, and hermetic wafer-scale optical packaging. An international team of leading researchers contributed to this book, and it presents examples and problems employing cutting-edge MOEM devices. It will inspire researchers to further advance the design, fabrication, and analysis of MOEM systems.


Book Details

Date Published: 21 April 2005
Pages: 636
ISBN: 9780819450210
Volume: PM126
Errata

Table of Contents
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Foreword xv
Preface xvii
Acknowledgments xix
1 Introduction 1
1.1 Integrated circuits and the evolution of micromachining 1
1.2 Micro-electro-mechanical systems review 3
1.3 New developments in micro-optics 8
1.4 Micro-optics in MEMS: MOEMS overview 11
1.4.1 New developments in optical switches 13
1.4.2 Tunable filters and WDMs 14
1.4.3 Digital mirror devices 15
1.4.4 MOEMS scanners 15
1.4.5 MOEMS technology applied to telecom 17
1.5 Microsystems: Terms and visions 17
1.5.1 MEMS and MOEMS activities worldwide 18
1.5.2 MEMS and MOEMS science worldwide 19
1.5.3 MEMS and MOEMS markets worldwide 19
1.6 Scope of this book 20
2 Microfabrication 27
2.1 Introduction 27
2.2 Bulk micromachining 32
2.2.1 Wet bulk micromachining 32
2.2.2 Dry bulk micromachining 35
2.3 Deep x-ray lithography (DXRL) 40
2.4 Surface micromachining 47
2.5 CMOS-compatible MEMS and MOEMS 57
2.6 Compound-semiconductor-based MEMS and MOEMS 60
2.7 Optics-specific issues for MOEMS 66
3 Micro-optics 75
3.1 Introduction 75
3.2 History 75
3.3 Deflection of light by micro- and nanostructures 77
3.3.1 Refractive and diffractive micro-optics 77
3.3.2 Artificial index material 78
3.3.3 Photonic crystals 79
3.3.4 Resonant filters 80
3.3.5 Demands on profile shapes 80
3.4 Binary and multilevel optics 82
3.4.1 Motivation 82
3.4.2 Fabrication of binary optics structures 82
3.4.3 Fabrication of multilevel structures 84
3.4.3.1 Concept 85
3.4.3.2 Diffraction efficiency 86
3.5 Technologies for continuous surface profiles 88
3.5.1 Lithographic technologies 89
3.5.1.1 Technologies based on surface tension 89
3.5.1.2 Analog lithography 96
3.5.2 Transfer of surface profiles into optical materials 110
3.5.2.1 Replication 110
3.5.2.2 Proportional transfer 113
3.6 Conclusion 114
4 Actuation and Sensing 121
4.1 Introduction 121
4.1.1 Microactuator 122
4.1.2 MOEMS-related sensors 124
4.1.3 Organization of this chapter 125
4.2 Electrostatic actuators 125
4.2.1 Background 125
4.2.2 In-plane actuation 129
4.2.2.1 Electrostatic electrode actuator 129
4.2.2.2 Comb drive 129
4.2.2.3 Scratch drive actuator 131
4.2.2.4 Linear electrostatic micromotor 131
4.2.2.5 Rotary electrostatic micromotors 132
4.2.3 Out-of-plane actuation 134
4.2.3.1 Parallel-plate drive 134
4.2.3.2 Torsion actuation 135
4.2.4 Three-dimensional actuation 138
4.3 Thermal actuators 139
4.3.1 Background 139
4.3.2 In-plane actuation 141
4.3.2.1 Pseudo-bimorph actuator 141
4.3.2.2 Bent-beam electrothermal actuator 142
4.3.2.3 U-shaped and serpentine-shaped electrothermal actuators 144
4.3.2.4 Linear microvibromotor 145
4.3.2.5 Rotary actuator 146
4.3.3 Out-of-plane actuation 147
4.3.3.1 Bimorph and multimorph 147
4.3.3.2 Symmetric pseudo-bimorph 149
4.3.4 Three-dimensional actuation 149
4.4 Shape memory actuators 150
4.4.1 Background 150
4.4.2 In-plane actuation 154
4.4.2.1 Linear SMA microactuators 154
4.4.2.2 SMA microgripper 155
4.4.3 Out-of-plane actuation 156
4.4.3.1 SMA bimorph 156
4.4.4 Three-dimensional actuation 158
4.5 Piezoelectric actuators 159
4.5.1 Background 159
4.5.2 In-plane actuation 163
4.5.2.1 LIGA piezoelectric actuator 163
4.5.2.2 Linear microworms 164
4.5.2.3 Inchworm 164
4.5.2.4 Rotation micromotor 165
4.5.3 Out-of-plane actuation 166
4.5.3.1 Bimorph 166
4.5.3.2 Multilayer cantilever 168
4.5.3.3 Torsion: 2D scanning mirror 169
4.5.4 Three-dimensional actuation 170
4.6 Magnetic actuators 171
4.6.1 Background 171
4.6.2 In-plane actuation 177
4.6.2.1 Latchable bistable actuator 177
4.6.2.2 Magnetic micromotor 179
4.6.3 Out-of-plane actuation 180
4.6.3.1 Cantilever and membrane actuation 180
4.6.3.2 Torsion actuation 181
4.6.4 Three-dimensional actuation 185
4.7 MOEMS-related sensors 187
4.7.1 Displacement sensor 187
4.7.2 Chemical sensor 190
4.7.3 Fluorescence detection sensor 191
4.7.4 Inertial sensor: accelerometer 194
4.7.5 Pressure sensor 196
5 Micro-Optic Components, Testing, and Applications 211
5.1 Micro-optic components 211
5.1.1 Micro-optical lenses 211
5.1.1.1 Vapor deposition 213
5.1.1.2 Mass transport 214
5.1.2 Liquid crystal optical components 214
5.1.3 Beam-shaping optical components 216
5.1.3.1 Optical collimator 216
5.1.3.2 Optical transformer 217
5.2 Optical testing 219
5.2.1 Optical profile measurement 219
5.2.1.1 Optical profilometers using focus detection 220
5.2.1.2 Optical profilometers based on white light interferometry 222
5.2.2 Surface deviation measurements 226
5.2.2.1 Spherical microlenses 226
5.2.2.2 Cylindrical microlenses 239
5.2.3 Wave aberration measurement 248
5.2.3.1 Weak phase objects 250
5.2.3.2 Microlenses as strong phase objects 253
5.2.3.3 Cylindrical lenses 259
5.2.3.4 Shearing methods and wavefront sensors 262
5.3 Micro-optics applications 266
5.3.1 Beam steering 266
5.3.2 Microlens and FPA integration 270
5.3.2.1 Micro-optics integration 270
5.3.2.2 Device characterization 272
6 Fiber Optic Systems 279
6.1 Introduction 279
6.2 Fundamentals 280
6.2.1 Optical fiber types 280
6.2.2 Key parameters of fiber optic components 283
6.2.3 Direct fiber or waveguide movement 284
6.2.4 Manipulation in a collimated beam 286
6.3 Fiber collimators and collimator arrays 287
6.3.1 Fiber arrays 287
6.3.2 Microlens array requirements 288
6.3.3 Fabrication of microlens arrays 291
6.3.4 Fiber array and microlens array mounting techniques 294
6.4 Fiber optic components with MOEMS 295
6.4.1 Variable optical attenuators 295
6.4.2 Dynamic gain and channel equalizers 298
6.4.3 Fiber optic switches 299
6.4.3.1 Switches with direct fiber or waveguide movement 299
6.4.3.2 Switches with 2D MOEMS 301
6.4.3.3 Digital matrix switches 304
6.4.3.4 Switch matrices with 3D MOEMS 308
6.4.3.5 Multimode fiber switches 311
6.4.4 Tunable sources and filters 312
6.5 Summary 314
7 Optical Scanners 319
7.1 Introduction 319
7.2 Operation principles and classifications of optical scanners 320
7.3 Scanning systems utilizing mechanical structures 321
7.3.1 Tilting micromirrors 321
7.3.2 Lens scanners 322
7.3.3 Micromotor scanners 324
7.3.4 Mirrors with a leverage mechanism 324
7.3.5 Surface-micromachined mirrors 326
7.4 Multidimensional scanning 327
7.5 Microactuators designed for scanning 328
7.5.1 Electrostatic scanners 328
7.5.1.1 Electrostatic actuators with parallel electrodes 329
7.5.1.2 Electrostatic actuation with tapered electrodes 332
7.5.1.3 Electrostatic comb-drive surface-micromachined scanners 332
7.5.1.4 Electrostatic comb drive for out-of-plane tilting mirrors 333
7.5.2 Piezoelectric scanners 336
7.5.2.1 Scanners using thin film piezoelectric actuators 336
7.5.2.2 Piezoelectric scanners in hybrid technologies 337
7.5.3 Electrothermal scanners 338
7.5.3.1 Principle of scanning 338
7.5.3.2 Device structural design 338
7.5.3.3 Characterization and testing 340
7.5.4 Magnetic scanners 341
7.5.4.1 Electromagnetic scanners 341
7.5.4.2 Magnetostrictive scanners 343
7.6 Comparative characteristics 345
7.7 Environmental and survival testing 345
7.8 Applications to commercial products 349
7.9 Applications of MEMS movable mirrors 350
7.9.1 Image display systems 350
7.9.1.1 Display systems using a single scanner 350
7.9.1.2 Display systems using arrays of light deflectors 352
7.9.1.3 Three-dimensional display 353
7.9.2 Components for optical communication 353
7.9.2.1 A digital (crossbar, 2D) switch array 353
7.9.2.2 Analog (beam-steering, 3D) switch 355
8 Display and Imaging Systems 365
8.1 Introduction 365
8.2 Display systems 366
8.2.1 Retinal scanning displays 367
8.2.1.1 MEMS scanners for display applications 367
8.2.1.2 System performance 384
8.2.2 Grating Light Valve displays 389
8.2.2.1 Pixel structure and operation 389
8.2.2.2 Pixel performance 392
8.2.2.3 System performance 393
8.2.3 Digital micromirror device 396
8.2.3.1 Pixel structure 397
8.2.3.2 Pixel operation 399
8.2.3.3 Intensity modulation and switching time 401
8.2.3.4 Fabrication 403
8.2.3.5 System performance 403
8.2.4 Other MEMS display technologies 405
8.3 Imaging systems 408
8.3.1 Scanning imaging systems 408
8.3.2 Confocal imaging systems 411
8.3.3 Other MEMS-based scanned-beam systems 420
8.3.4 Scanned-probe imaging 422
8.3.5 Aberration correction for scanned imaging systems 423
8.3.6 MOEM spatial light modulators in scanned imaging systems 426
8.3.7 Array-based imaging systems (focal plane systems) 428
8.3.7.1 Thermal imaging focal plane arrays 428
9 Adaptive Optics 449
9.1 Introduction 449
9.1.1 History of adaptive optics 449
9.1.2 Conventional deformable-mirror technology 452
9.1.3 Motivations for MEMS deformable mirrors 453
9.1.4 The center for adaptive optics 453
9.1.5 The coherent communications, imaging, and targeting 457
9.2 Membrane deformable micromirrors 458
9.3 Polysilicon deformable micromirrors 460
9.4 Single crystal silicon deformable micromirrors 463
9.5 Metal deformable micromirrors 465
9.6 Packaging and electronics 466
9.7 Future trends and challenges 468
10 MEMS and MOEMS CAD and Simulation 473
10.1 Introduction 473
10.2 3D device simulation 475
10.2.1 Introduction 475
10.2.2 Process simulation 475
10.2.3 FEM and BEM simulation 477
10.2.3.1 Introduction 477
10.2.3.2 FEM simulation 478
10.2.3.3 BEM analysis 480
10.2.3.4 Comparison of FEM and BEM 481
10.2.3.5 Meshing 482
10.2.4 Noncontinuum methods 483
10.3 Actuator design and simulation 483
10.3.1 Introduction 483
10.3.2 Simulation of thermal actuators 483
10.3.3 Simulation of electrostatic actuators 485
10.4 Optical solvers 487
10.4.1 Introduction 487
10.4.2 Propagation phenomena 488
10.4.3 Optical theories 488
10.4.4 Mathematical techniques and approximations 489
10.4.5 Codes 490
10.5 System-level simulations 490
10.5.1 Optimization 493
10.5.2 Statistical analysis 494
10.5.3 Dedicated MOEMS simulation and cosimulation 495
10.5.4 System simulation example�pull-in computation 496
10.5.5 Packaging simulation 497
10.5.6 Reduced-order modeling 498
10.5.6.1 Example application: Reduction of a micromirror 500
10.6 Physical tools and verification 501
10.6.1 Design rule checking, extractors, layout versus schematic, and parasitics 503
10.7 Material, process, and reliability issues 504
10.8 Conclusions 504
11 MEMS and MOEMS Packaging 511
11.1 Overview 511
11.2 Background and introduction 511
11.2.1 Mixed signals, mixed domains, and mixed scales packaging:
Towards the next generation of application-specific integrated systems 511
11.2.2 Microelectromechanical systems 513
11.3 Challenges in MEMS system integration 514
11.3.1 Release and stiction 516
11.3.2 Dicing 517
11.3.3 Die handling 518
11.3.4 Wafer-level encapsulation 518
11.3.5 Stress 519
11.3.6 Outgassing 519
11.3.7 Testing 520
11.3.8 State of the art in MEMS and MOEMS packaging 520
11.3.9 Summary and future directions 522
11.4 Packaging considerations and guidelines related to the Digital Micromirror Device 523
11.4.1 Introduction and background to MOEMS devices and particularly the DMD 523
11.4.2 Parameters influencing DMD packaging 526
11.4.3 DMD package design 527
11.4.3.1 DMD die size 528
11.4.3.2 Package piece parts 530
11.4.3.3 Substrate design 531
11.4.3.4 Window design 533
11.4.3.5 Package size 534
11.4.3.6 Headspace getters 534
11.4.4 DMD hermetic package assembly 535
11.4.5 Future packaging challenges 535
12 MEMS and MOEMS Materials 541
12.1 Introduction 541
12.2 Effects of materials on MOEMS 541
12.3 Measuring materials properties 549
12.3.1 Wafer curvature 549
12.3.2 Microstructures 550
12.3.3 In-process monitoring methods 555
12.4 Residual stress engineering 558
12.5 Conclusions 558
Problems and Exercises 561
Acronyms 585
Index

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