MEMS and Nanotechnology for Gas Sensors

MEMS and Nanotechnology for Gas Sensors

by Sunipa Roy, Chandan Kumar Sarkar
Released December 2017
Publisher(s): CRC Press
ISBN: 9781351830249

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Book description

How Can We Lower the Power Consumption of Gas Sensors?

There is a growing demand for low-power, high-density gas sensor arrays that can overcome problems relative to high power consumption. Low power consumption is a prerequisite for any type of sensor system to operate at optimum efficiency. Focused on fabrication-friendly microelectromechanical systems (MEMS) and other areas of sensor technology, MEMS and Nanotechnology for Gas Sensors explores the distinct advantages of using MEMS in low power consumption, and provides extensive coverage of the MEMS/nanotechnology platform for gas sensor applications.

This book outlines the microfabrication technology needed to fabricate a gas sensor on a MEMS platform. It discusses semiconductors, graphene, nanocrystalline ZnO-based microfabricated sensors, and nanostructures for volatile organic compounds. It also includes performance parameters for the state of the art of sensors, and the applications of MEMS and nanotechnology in different areas relevant to the sensor domain.

In addition, the book includes:

  • An introduction to MEMS for MEMS materials, and a historical background of MEMS
  • A concept for cleanroom technology
  • The substrate materials used for MEMS
  • Two types of deposition techniques, including chemical vapour deposition (CVD)
  • The properties and types of photoresists, and the photolithographic processes
  • Different micromachining techniques for the gas sensor platform, and bulk and surface micromachining
  • The design issues of a microheater for MEMS-based sensors
  • The synthesis technique of a nanocrystalline metal oxide layer
  • A detailed review about graphene; its different deposition techniques; and its important electronic, electrical, and mechanical properties with its application as a gas sensor
  • Low-cost, low-temperature synthesis techniques
  • An explanation of volatile organic compound (VOC) detection and how relative humidity affects the sensing parameters

MEMS and Nanotechnology for Gas Sensors provides a broad overview of current, emerging, and possible future MEMS applications. MEMS technology can be applied in the automotive, consumer, industrial, and biotechnology domains.

Table of contents

  1. Cover
  2. Half Title
  3. Title Page
  4. Copyright Page
  5. Dedication
  6. Table of Contents
  7. Preface
  8. Authors
  9. Section I Fabrication Procedure
    1. 1. Introduction
      1. 1.1 Cleanroom Technology
      2. 1.2 Microelectromechanical System
        1. 1.2.1 History
        2. 1.2.2 Definitions and Classifications
        3. 1.2.3 Market and Application
        4. 1.2.4 Materials for MEMS
      3. 1.3 Significance of MEMS
      4. References
    2. 2. Substrate for MEMS
      1. 2.1 Introduction
      2. 2.2 Silicon: The Base
        1. 2.2.1 Silicon as a Semiconductor
        2. 2.2.2 Surface Contamination
          1. 2.2.2.1 Contaminants on Silicon Wafers
        3. 2.2.3 Cleaning and Etching
          1. 2.2.3.1 Cleaning
          2. 2.2.3.2 Etching
      3. 2.3 Dielectrics
        1. 2.3.1 Silicon Dioxide (SiO2)
        2. 2.3.2 Silicon Nitride (Si3N4)
        3. 2.3.3 Low-Temperature Oxidation
        4. 2.3.4 Oxide Properties
      4. References
    3. 3. Deposition
      1. 3.1 Physical Vapour Deposition
        1. 3.1.1 Vacuum Technology for MEMS
        2. 3.1.2 e-Beam Evaporation
        3. 3.1.3 Thermal Evaporation
        4. 3.1.4 Sputtering
        5. 3.1.5 Molecular Beam Epitaxy
      2. 3.2 Chemical Vapour Deposition
        1. 3.2.1 Atmospheric Pressure CVD (APCVD)
        2. 3.2.2 Plasma CVD
        3. 3.2.3 MOCVD
      3. 3.3 Metallization
        1. 3.3.1 Different Types of Metallization
        2. 3.3.2 Methods
          1. 3.3.2.1 Filament Evaporation
          2. 3.3.2.2 Electron Beam Evaporation
          3. 3.3.2.3 Induction Evaporation
          4. 3.3.2.4 Sputtering
        3. 3.3.3 Wire Bonding
      4. References
    4. 4. Photolithography: Pattern Transfer
      1. 4.1 Introduction
      2. 4.2 Photoresist for Structuring
      3. 4.3 Some Important Properties of Photoresist
        1. 4.3.1 Sensitivity
        2. 4.3.2 Adhesion
        3. 4.3.3 Etch Resistance
        4. 4.3.4 Bubble Formation
      4. 4.4 Types of Photoresists: Negative and Positive Photoresists
        1. 4.4.1 Negative Photoresists
        2. 4.4.2 Positive Photoresists
      5. 4.5 Designing of Mask Layout
      6. 4.6 Photolithography Process
      7. 4.7 Application of Photoresist and Prebake
      8. 4.8 Alignment, Exposure, and Pattern Formation
      9. 4.9 PR Developer and Postbake
      10. 4.10 Stripping (Photoresist Removal)
      11. 4.11 Some Advanced Lithographic Techniques
        1. 4.11.1 Electron Beam Lithography
        2. 4.11.2 Ion Beam Lithography
        3. 4.11.3 X-Ray Lithography
        4. 4.11.4 Phase-Shift Lithography
    5. 5. Structuring MEMS: Micromachining
      1. 5.1 Introduction
      2. 5.2 Bulk Micromachining
        1. 5.2.1 Wet Etching
          1. 5.2.1.1 Isotropic and Anisotropic: Empirical Observations
          2. 5.2.1.2 Convex and Concave Corner Compensations
        2. 5.2.2 Dry Etching
      3. 5.3 Surface Micromachining
        1. 5.3.1 Processes
        2. 5.3.2 Hurdles
        3. 5.3.3 Lift-Off versus Etch Back
          1. 5.3.3.1 Lift-Off
          2. 5.3.3.2 Etch Back
      4. 5.4 Etch-Stop Technique
        1. 5.4.1 Boron Etch Stop
        2. 5.4.2 Electrochemical Etch Stop
        3. 5.4.3 Photo-Assisted Electrochemical Etch Stop (for n-Type Silicon)
        4. 5.4.4 Etch Stop at Thin Films: Silicon on Insulator
      5. 5.5 High-Aspect-Ratio Micromachining
        1. 5.5.1 LIGA
        2. 5.5.2 Laser Micromachining
      6. References
    6. 6. Microheaters for Gas Sensor
      1. 6.1 Introduction
      2. 6.2 Need of Microheater
      3. 6.3 Types of Microheater
        1. 6.3.1 Closed-Membrane Type
        2. 6.3.2 Suspended-Membrane Hotplates
      4. 6.4 Microheater Design Issues
      5. 6.5 Heater Material Selection
      6. 6.6 Heater Geometry Selection
      7. 6.7 Function of Interdigitated Electrode
      8. 6.8 Software Used
        1. 6.8.1 Temperature Distribution
        2. 6.8.2 Mechanical Stability
        3. 6.8.3 Thermal Response Time
      9. 6.9 Heating Power Consumption
      10. 6.10 Fabrication of Microheater
      11. 6.11 Microheater Array
      12. References
  10. Section II Sensor Applications
    1. 7. Semiconductors as Gas Sensors
      1. 7.1 Introduction
      2. 7.2 Development of Semiconductor Sensors
        1. 7.2.1 Fundamentals of Semiconductor Sensors
        2. 7.2.2 Classification of Semiconductor Sensors
        3. 7.2.3 Different Structures of Semiconductor Gas Sensors
          1. 7.2.3.1 Resistive-Type Metal Oxide–Based Gas Sensors
          2. 7.2.3.2 Schottky-Type Metal Oxide–Based Gas Sensor
          3. 7.2.3.3 Metal Oxide Homojunction Gas Sensor
          4. 7.2.3.4 Metal Oxide Heterojunction Gas Sensor
          5. 7.2.3.5 Mixed Metal Oxide Gas Sensors
          6. 7.2.3.6 MEMS Gas Sensors
      3. 7.3 What Is a Nanosensor?
        1. 7.3.1 Thin Film Sensors
        2. 7.3.2 Thick-Film Sensors
          1. 7.3.2.1 Thick-Film Materials
      4. 7.4 Solid-State Chemical Sensors
        1. 7.4.1 Metal Oxide Semiconductors
        2. 7.4.2 Nanocrystalline Metal Oxide Semiconductors
        3. 7.4.3 Adsorption of Oxygen: Analyses
        4. 7.4.4 Reaction between Gas (e.g. CH4) and Oxygen
        5. 7.4.5 Role of Catalyst on Gas Sensing Mechanism
        6. 7.4.6 Thick- and Thin-Film Fabrication Process
          1. 7.4.6.1 Bulk Growth
          2. 7.4.6.2 Substrate Growth
          3. 7.4.6.3 Chemical Vapour Deposition
          4. 7.4.6.4 Sputtering
          5. 7.4.6.5 Chemical Route
        7. 7.4.7 Sensor Characterizations
          1. 7.4.7.1 X-Ray Diffraction
          2. 7.4.7.2 Determination of Crystal Size
          3. 7.4.7.3 Field Emission Scanning Electron Microscopy
          4. 7.4.7.4 Transmission Electron Microscopy
          5. 7.4.7.5 Photoluminescence Spectroscopy
          6. 7.4.7.6 Fourier Transform Infrared Spectroscopy
          7. 7.4.7.7 Qualitative Analysis
          8. 7.4.7.8 UV/VIS Spectroscopy
          9. 7.4.7.9 Raman Spectroscopy
        8. 7.4.8 Sensor Reliability Issues
      5. References
    2. 8. Sensing with Graphene
      1. 8.1 Introduction
      2. 8.2 Properties of Graphene
        1. 8.2.1 Electronic Property
        2. 8.2.2 Mechanical Properties
        3. 8.2.3 Optical Properties
        4. 8.2.4 Electronic Transport
        5. 8.2.5 Anomalous Quantum Hall Effect
        6. 8.2.6 Magnetic Properties
        7. 8.2.7 Thermal Properties
      3. 8.3 Characterization Techniques
        1. 8.3.1 Optical Microscopy
        2. 8.3.2 Field Emission Scanning Electron Microscopy
        3. 8.3.3 Atomic Force Microscopy
        4. 8.3.4 Diffraction Imaging Electron Microscopy
        5. 8.3.5 Transmission Electron Microscopy
        6. 8.3.6 Raman Scattering
      4. 8.4 Synthesis of Single-Layer Graphene/Few-Layer Graphene
        1. 8.4.1 Micromechanical Exfoliation
        2. 8.4.2 Chemical Exfoliation
        3. 8.4.3 Epitaxial Growth on Silicon Carbide (SiC)
        4. 8.4.4 Chemical Vapour Deposition
      5. 8.5 Graphene Oxide
      6. 8.6 Potential Application
        1. 8.6.1 Graphene Sensors
      7. 8.7 Summary
      8. References
    3. 9. Nanocrystalline ZnO-Based Microfabricated Chemical Sensor
      1. 9.1 Introduction
      2. 9.2 Device Structure: Vertical and Horizontal
      3. 9.3 Comparison of Vertical and Horizontal Structure
      4. 9.4 Metal–Insulator–Metal Structure
      5. 9.5 Nanocrystalline ZnO as Sensing Material
      6. 9.6 Sensing Layer Deposition by Chemical Route
        1. 9.6.1 Sol-Gel Method for Synthesis of ZnO Thin Films
        2. 9.6.2 Chemical Bath Deposition Technique
          1. 9.6.2.1 Growth Mechanism
        3. 9.6.3 Chemical Deposition Technique
      7. References
    4. 10. Nanostructures for Volatile Organic Compound Detection
      1. 10.1 Introduction
      2. 10.2 Volatile Organic Compounds
      3. 10.3 Different Nanostructures
        1. 10.3.1 Fabrication Processes
        2. 10.3.2 Characterization Processes
      4. 10.4 Sensing Mechanism
      5. 10.5 Measurement Technique
      6. 10.6 Effect of Relative Humidity on VOC Detection
      7. References
    5. 11. Sensor Interfaces
      1. 11.1 Signal Processing
      2. 11.2 Smart Sensors
        1. 11.2.1 System Components
      3. 11.3 Interface Systems
      4. References
    6. 12. MEMS- and Nanotechnology-Enabled Sensor Applications
      1. 12.1 MEMS and Nanotechnology
      2. 12.2 Automotive Applications: An Elaborated Study
        1. 12.2.1 Safety
        2. 12.2.2 Vehicle Diagnostics/Monitoring
        3. 12.2.3 Engine/Drive Train
        4. 12.2.4 Comfort, Convenience and Security
      3. 12.3 Home Appliances
      4. 12.4 Aerospace
        1. 12.4.1 Turbulence Control
      5. 12.5 Environmental Monitoring
      6. 12.6 Process Engineering
      7. 12.7 Medical Diagnostic
      8. References
  11. Index

Product information

  • Title: MEMS and Nanotechnology for Gas Sensors
  • Author(s): Sunipa Roy, Chandan Kumar Sarkar
  • Release date: December 2017
  • Publisher(s): CRC Press
  • ISBN: 9781351830249