Microsensors, MEMS, and Smart Devices

Transcription

1 Microsensors, MEMS, and Smart Devices Julian W. Gardner University of Warwick, UK Vijay K. Varadan Osama O. Awadelkarim Pennsylvania State University, USA JOHN W1LEY & SONS, LTD Chichester New York Weinheim Brisbane Singapore Toronto

2 Contents Preface About the Authors Acknowledgments xiii xv xvii 1 Introduction Historical Development of Microcteetronics Evolution of Microsensors Evolution of MEMS Emergence of Micromachines 7 References 8 2 Electronic Materials and Processing Introduction Electronic Materials and their Deposition Oxide Film Formation by Thermal Oxidation Deposition of Silicon Dioxide and Silicon Nitride Polysilicon Film Deposition Pattern Transfer The Lithographie Process Mask Formation Resist Lift-off Technique Etching Electronic Materials Wet Chemical Etching Dry Etching Doping Semiconductors Diffusion Ion Implantation Concluding Remarks 32 References 34 3 MEMS Materials and their Preparation Overview Atomic Structure and the Periodic Table 35

3 vi CONTENTS Atomic Bonding Crystallinity Metals Physical and Chemical Properties Metallisation Semiconductors Scmiconductors: Electrical and Chemical Properties Semiconductors: Growth and Deposition Ceramic, Polymerie, and Composite Materials 58 References 59 Standard Microelectronic Technologies (nlroduction Wafer Preparation Crystal Growth Wafcr Manufacture Epilaxial Deposiüon Monoliihic Processing Bipolar Processing Characteristics of BJTs MOS Processing Characteristics of FETs SOI CMOS Processing Monolithic Mounting Die Bonding and Wire Bonding Tape-Automated Bonding Flip TAB Bonding Flip-Chip Mounting Printed Circuit Board Technologies Solid Board Flexible Board Plaslic Mouldcd Hybrid and MCM Technologies Thick Film Multichip Modules Ball Grid Array Programmable Devices And ASICs 112 References Silicon Micromachining: Bulk fntroduetion Isotropie and Orientation-Dcpcndcnt Wet Etching Etch-Stop Techniques Doping-Selective Etching (DSE) Convcntional Bias-Dependent BSE or Electrochemical 126 Ftch-Stop

4 CONTENTS vii Selective Etching of n-type Silicon by Pulsed 131 Potential Anodisation Photovoltaic Eleclrochemical Etch-Stop Technique 131 (PHET) 5.4 Dry Etching Buried Oxide Process Silicon Fusion Bonding Wafer Fusion Annealing Treatment Fusion of Silicon-Based Materials Anodic Bonding Concluding Remarks 143 Refcrences 143 d Silicon Micromachining: Surface Introduction Sacrificial Laycr Technology Simple Process Sacrificial Layer Processes Utilising more lhan One 151 Structural Laycr 6.3 Material Systems in Sacrificial Layer Technology Polycrystalline Silicon and Silicon Dioxide Polyimide and Aluminum Silicon Nitride/Polycryslalline Silicon and 157 Tungsten/Silicon Dioxide 6.4 Surface Micromachining using Plasma Etching Combined IC Technology and Anisotropie Wct Etching Proccsscs Using Both Bulk and Surface Micromachining Adhcsion Problems in Surface Micromachining Surface Versus Bulk Micromachining 172 References Microstereolithography for MEMS Introduction Photopolymerisation Stercoiithographic System Microstereolithography Scanning Method ClassicalMSL H Process Mass-IH Process Super-IH Process Two-photon MSL Other MSL Approaches Projection Method Mask-Projection MSL Dynamic Mask-Projection MSL 196

5 CONTENTS 7.7 Polymerie MEMS Architecture with Silicon, Metal, and Ceramics '" CeramicMSL Metallic Microstructures Metal-Polymer Microstructures Localised Electrochemical Deposition Combined Silicon and Polymerie Structurcs Architecture Combination by Photoforming Process MSL Integrated with Thick Film Lithography AMANDA Process Applications Microactuators Fabricated by MSL 2L Microconcentrator Microdevices Fabricated by the AMANDA Process Concluding Remarks 224 Referenccs Microsensors Introduction Thermal Sensors Resislivc Temperature Microsensors Microthermocouples Thermodiodes and Thermotransistors SAW Temperature Sensor Radiation Sensors Photoconductive Devices Photovoltaic Devices Pyroelectric Devices Microantenna Mechanical Sensors Overview Micromecbanical Components and Staues Microshuttles and Dynamics Mechanical Microstructures Pressure Microsensors Microaccelerometers Microgyromcters Flow Microsensors Magnetic Sensors Magnetogalvanic Microsensors Magnetoresistive Devices Magnetodiodes and Magnetotransistors Acoustic Devices and SQUIDs Bio(chemical) Sensors Conduclimetric Devices Potentiometrie Devices Othcrs 296

6 CONTENTS 8.7 Concluding Remarks 300 References Introduction to SAW Devices Introduction Saw Device Development and Hislory The Piezoelectric Effect Interdigital Transducers in SAW Devices Acoustic Waves Rayleigh Surface Acoustic Waves Shcar Horizontal Acoustic Waves Love Surface Acoustic Waves Concluding Remarks 314 References Surface Acoustic Waves in Solids Introduction Acoustic Wave Propagation Acoustic Wave Propagation Representation Introduction to Acoustics Particle Displacement and Strain Stress The Piezoelectric Effect Acouslic Wavc Propagation Uniform Plane Waves in a Piezoelectric Solid: 325 Quasi-Static Approximation Shcar Horizontal or Acoustic Plate Modes Love Modes Concluding Remarks 334 References IDT Microsensor Parameter Measurement Introduction to IDT SAW Sensor Instrumentation Acoustic Wave Sensor Instrumentation Introduction Network Analyser and Vector Voltmeter Analogue (Amplitude) Measuring System Phase Measurement System Frequency Measurement System Acouslic Wavc Sensor Output Frequency Translation Measurement Setup Calibration 344 References IDT Microsensor Fabrication Introduction Saw-IDT Microsensor Fabrication 347

7 x CONTENTS Mask Generation Wafer Preparation Metallisation Photolithography Water Dicing Deposition of Waveguide Layer Introduction TMS PBCVD Process and Conditions Concluding Remarks 358 References IDT Microsensors Introduction Saw Device Modeling via Coupled-mode Theory Wireless SAW-based Microsensors Applications Strain Sensor Temperature Sensor Pressure Sensor Humidity Sensor SAW-Based Gyroscope Concluding Remarks 395 References MEMS-TDT Microsensors Introduction Principles of a MEMS-1DT Accclcromctcr Fabrication of a MEMS-IDT Accelerometer Fabrication of the SAW Device Integration of the SAW Device and Scismic Mass Testing of a MFMS-1DT Accelerometer Measurement Setup Calibration Procedure Time Domain Measurement Experimental Fabrication of Scismic Mass Wireless Readout Hybrid Accelerometers and Gyroscopes Concluding Remarks 416 References Smart Sensors and MEMS Introduction Smart Sensors MEMS Devices Concluding Remarks 442 References 443

8 Appendices A. List of Abbrcviations 445 B. Eist of Symbols and Prefixes 449 C. List of Some Important Terms 455 D. Fundamental Constants 457 E. Unit Conversion Factors 459 F. Properties of Electronic & MEMS Metallic Materials 461 G. Properties of Electronic & MEMS Seniiconducting Materials 463 H. Properties of Electronic & MEMS Ceramic and Polymer Materials 465 I. Complex Reciprocity Relation and Perturbation Analysis 467 J. Couplcd-mode Modeling of a SAW Device 477 K. Suggested Further Reading 481 L. Webography 487 M. List of Worked Fxamples 491 Index 493