Chapter 1: Introduction
1.0. Preview
1.1. The History of MEMS Development
1.1.1. From the Beginning to 1990
1.1.2. From 1990 to 2001
1.1.3. 2002 to present
1.1.4. Future Trends
1.2. The Intrinsic Characteristics of MEMS
1.2.1. Miniaturization
1.2.2. Microelectronics Integration
1.2.3. Parallel Fabrication with Precision
1.3. Devices: Sensors and Actuators
1.3.1. Energy Domains and Transducers
1.3.2. Sensors Considerations
13.3. Sensor Noise and Design Complexity
1.3.4. Actuators Considerations
Summary
Problems
References
Chapter 2: First-Pass Introduction to Microfabrication
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2.1. Overview of Microfabrication
2.2. Essential Overview of Frequently Used Microfabrication Processes
2.2.1. Photolithography
2.2.2. Thin film deposition
2.2.3. Thermal oxidation of silicon
2.2.4. Wet Etching
2.2.5. Silicon anisotropic etching
2.2.6. Plasma etching and reactive ion etching
2.2.7. Doping
2.2.8. Wafer dicing
2.2.9. Wafer bonding
2.3. The Microelectronics Fabrication Process Flow
2.4. Silicon-based MEMS Processes
2.5. Packaging and Integration
2.5.1. Integration Options
2.5.2. Encapsulation
2.6. New Materials and Fabrication Processes
2.7. Process Selection and Design
2.7.1. Points of Consideration for Deposition Processes
2.7.2. Points of Consideration for Etching Processes
2.7.3. Ideal Rules for Building a Process Flow
2.7.4. Rules for Building a Robust Process
Summary
Problems
References
Chapter 3: Review of Essential Electrical and Mechanical Concepts
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3.1. Conductivity of Semiconductors
3.1.1. Semiconductor Materials
3.1.2. Calculation of Charge Carrier Concentration
3.1.3. Conductivity and Resistivity
3.2. Crystal Planes and Orientations
3.3. Stress and Strain
3.3.1. Internal Force Analysis: Newton’s Laws of Motion
3.3.2. Definitions of Stress and Strain
3.3.3. General Scalar Relation between Tensile Stress and Strain
3.3.4. Mechanical Properties of Silicon and Related Thin Films
3.3.5. General Stress — Strain Relations
3.4. Flexural Beam Bending Analysis under Simple Loading Conditions
3.4.1. Types of Beams
3.4.2. Longitudinal Strain under Pure Bending
3.4.3. Deflection of Beams
3.4.4. Finding the Spring Constants
3.5. Torsional Deflections
3.6. Intrinsic Stress
3.7. Dynamic System, Resonant Frequency, and Quality Factor
3.7.1. Dynamic System and Governing Equation
3.7.2. Response under Sinusoidal Resonant Input
3.7.3. Damping and Quality Factor
3.7.4. Resonant Frequency and Bandwidth
3.8. Active Tuning of Spring Constant and Resonant Frequency
3.9. A List of Suggested Courses and Books
Summary
Problems
References
Chapter 4: Electrostatic Sensing and Actuation
Section 4.0. Preview
Section 4.1. Introduction to Electrostatic Sensors and Actuators
Section 4.2. Parallel Plate Capacitor
4.2.1. Capacitance of Parallel Plates
4.2.2. Equilibrium Position of Electrostatic Actuator under Bias
4.2.3. Pull-in Effect of Parallel-Plate Actuators
Section 4.3. Applications of Parallel-Plate Capacitors
4.3.1. Inertia Sensor
4.3.2. Pressure Sensor
4.3.3. Flow Sensor
4.3.4. Tactile sensor
4.3.5. Parallel-plate actuators
Section 4.4. Interdigitated Finger Capacitors
Section 4.5. Applications of Comb-Drive Devices
4.5.1. Inertia Sensors
4.5.2. Actuators
Summary
Problems
References
Chapter 5: Thermal Sensing and Actuation
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5.1. Introduction
5.1.1. Thermal Sensors
5.1.2. Thermal Actuators
5.1.3. Fundamentals of Thermal Transfer
5.2. Sensors and Actuators Based on Thermal Expansion
5.2.1. Thermal Bimorph Principle
5.2.2. Thermal Actuators with a Single Material
5.3. Thermal Couples
5.4. Thermal Resistors
5.5. Applications
5.5.1. Inertia Sensors
5.5.2. Flow Sensors
5.5.3. Infrared Sensors
5.5.4. Other Sensors
Summary
Problems
References
Chapter 6: Piezoresistive Sensors
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6.1. Origin and Expression of Piezoresistivity
6.2. Piezoresistive Sensor Materials
6.2.1. Metal Strain Gauges
6.2.2. Single Crystal Silicon
6.2.3. Polycrystalline Silicon
6.3. Stress Analysis of Mechanical Elements
6.3.1. Stress in Flexural Cantilevers
6.3.2. Stress and Deformation in Membrane
6.4. Applications of Piezoresistive Sensors
6.4.1. Inertial Sensors
6.4.2. Pressure Sensors
6.4.3. Tactile sensor
6.4.4. Flow sensor
Summary
Problems
References
Chapter 7: Piezoelectric Sensing and Actuation
7.0. Preview
7.1. Introduction
7.1.1. Background
7.1.2. Mathematical description of piezoelectric effects
7.1.3. Cantilever piezoelectric actuator model
7.2. Properties of Piezoelectric Materials
7.2.1. Quartz
7.2.2. PZT
7.2.3. PVDF
7.2.4. ZnO
7.2.5. Other Materials
7.3. Applications
7.3.1. Inertia Sensors
7.3.2. Acoustic Sensors
7.3.3. Tactile Sensors
7.3.4. Flow Sensors
7.3.5. Surface Elastic Waves
Summary
Problems
References
Chapter 8: Magnetic Actuation
8.0. Preview
8.1. Essential Concepts and Principles
8.1.1. Magnetization and Nomenclatures
8.1.3. Selected Principles of Micro Magnetic Actuators
8.2 Fabrication of Micro Magnetic Components
8.2.1. Deposition of Magnetic Materials
8.2.2. Design and Fabrication of Magnetic Coil
8.3. Case Studies of MEMS Magnetic Actuators
Summary
Problems
References
Chapter 9: Summary of Sensing and Actuation Methods
9.0. Preview
9.1. Comparison of Major Sensing and Actuation Methods
9.2. Other Sensing and Actuation Methods
9.2.1. Tunneling Sensing
9.2.3 Optical Sensing
9.2.4. Field Effect Transistors
9.2.5. Radio Frequency Resonance Sensing
Summary
Problems
References
Chapter 10: Bulk Micromachining and Silicon Anisotropic Etching
10.0. Preview
10.1. Introduction
10.2. Anisotropic Wet Etching
10.2.1. Introduction
10.2.2. Rules of Anisotropic Etching–Simplest Case
10.2.3. Rules of Anisotropic Etching–Complex Structures
10.2.4. Forming Protrusions
10.2.5. Interaction of Etching Profiles from Isolated Patterns
10.2.6. Summary of design methodology
10.2.7. Chemicals for Wet Anisotropic Etching
10.3. Dry Etching and Deep Reactive Ion Etching
10.4. Isotropic Wet Etching
10.5. Gas Phase Etchants
10.6. Native Oxide
10.7. Special Wafers and Techniques
Summary
Problems
References
Chapter 11: Surface Micromachining
11.0. Preview
11.1. Basic Surface Micromachining Processes
11.1.1. Sacrificial Etching Process
11.1.2. Micro Motor Fabrication Process–A First Pass
11.2.3. Micro Motor Fabrication Process–A Second Pass
11.1.4. Micro Motor Fabrication Process–Third Pass
11.2. Structural and Sacrificial Materials
11.2.1. Material Selection Criteria for a Two-layer Process
11.2.2. Thin Films by Low Pressure Chemical Vapor Deposition
11.2.3. Other Surface Micromachining Materials and Processes
11.3. Acceleration of Sacrificial Etch
11.4. Stiction and Anti-stiction Methods
Summary
Problems
References
Chapter 12: Process Synthesis: Putting It all Together
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12.1. Process for Suspension Beams
12.2. Process for Membranes
12.3. Process for Cantilevers
12.3.1. SPM Technologies Case Motivation
12.3.2. General Fabrication Methods for Tips
12.3.3. Cantilevers with Integrated Tips
12.3.4. Cantilevers with Integrated Sensors
12.3.5. SPM Probes with Actuators
12.4. Practical Factors Affecting Yield of MEMS
Summary
Problems
References
Chapter 13: Polymer MEMS
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13.1. Introduction
13.2. Polymers in MEMS
13.2.1. Polyimide
13.2.2. SU-8
13.2.3. Liquid Crystal Polymer (LCP)
13.2.4. PDMS
13.2.5. PMMA
13.2.6. Parylene
13.2.7. Fluorocarbon
13.2.8. Other Polymers
13.3. Representative Applications
13.3.1. Acceleration Sensors
13.3.2. Pressure Sensors
13.3.3. Flow sensors
13.3.4. Tactile Sensors
Summary
Problems
Reference
Chapter 14: Micro Fluidics Applications
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14.1. Motivation for Microfluidics
14.2. Essential Biology Concepts
14.3. Basic Fluid Mechanics Concepts
14.3.1. The Reynolds Number and Viscosity
14.3.2. Methods for Fluid Movement in Channels
14.3.3. Pressure Driven Flow
14.3.4. Electrokinetic Flow
14.3.5. Electrophoresis and Dielectrophoresis
14.4. Design and Fabrication of Selective Components
14.4.1. Channels
14.4.2. Valves
Summary
Problems
References
Chapter 15: Case Studies of Selected MEMS Products
15.0. Preview
15.1. Case Studies: Blood Pressure (BP) Sensor
15.1.1. Background and History
15.1.2. Device Design Considerations
15.1.3. Commercial Case: NovaSensor BP Sensor
15.2. Case Studies: Microphone
15.2.1. Background and History
15.2.2. Design Considerations
15.2.3. Commercial Case: Knowles Microphone
15.3. Case Studies: Acceleration Sensors
15.3.1. Background and History
15.4.2. Design Considerations
15.4.1. Commercial Case: Analog Devices and MEMSIC
15.4. Case Studies: Gyros
15.4.1. Background and History
15.4.2. The Coriolis Force
15.4.3. MEMS Gyro Design
15.4.4. Single Axis Gyro Dynamics
15.4.4. Commercial Case: InvenSense Gyro
15.5 Summary of Top Concerns for MEMS Product Development
15.5.1. Performance and Accuracy
15.5.2. Repeatability and Reliability
15.5.3. Managing the Cost of MEMS Products
15.5.4. Market Uncertainties, Investment, and Competition
Summary
Problems
References
Appendix 1: Characteristics of selected MEMS material
Appendix 2: Frequently Used Formula for Beams, Cantilevers, and Plates
Appendix 3: Basic Tools for Dealing with a Mechanical Second-order Dynamic System
Appendix 4: Most Commonly Encountered Materials
Appendix 5: Most Commonly Encountered Material Removal Process Steps
Appendix 6: A List of General Compatibility between General Materials and Processes
Appendix 7: Comparison of Commercial Inertial Sensors
Answers to selected problems
Index
