Materials and Failures in MEMS and NEMS E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 697

Veröffentlichungsjahr: 2015

Beschreibung

The fabrication of MEMS has been predominately achieved by etching the polysilicon material. However, new materials are in large demands that could overcome the hurdles in fabrication or manufacturing process. Although, an enormous amount of work being accomplished in the area, most of the information is treated as confidential or privileged. It is extremely hard to find the meaningful information for the new or related developments. This book is collection of chapters written by experts in MEMS and NEMS technology. Chapters are contributed on the development of new MEMS and NEMS materials as well as on the properties of these devices. Important properties such as residual stresses and buckling behavior in the devices are discussed as separate chapters. Various models have been included in the chapters that studies the mode and mechanism of failure of the MEMS and NEMS. This book is meant for the graduate students, research scholars and engineers who are involved in the research and developments of advanced MEMS and NEMS for a wide variety of applications. Critical information has been included for the readers that will help them in gaining precise control over dimensional stability, quality, reliability, productivity and maintenance in MEMS and NEMS. No such book is available in the market that addresses the developments and failures in these advanced devices.

Leseprobe

Contents

Cover

Half Title page

Title page

Copyright page

Preface

Chapter 1: Carbon as a MEMS Material

1.1 Introduction

1.2 Structure and Properties of Glassy Carbon

1.3 Fabrication of C-MEMS Structures

1.4 Integration of C-MEMS Structures with Other Materials

1.5 Conclusion

References

Chapter 2: Intelligent Model-Based Fault Diagnosis of MEMS

2.1 Introduction

2.2 Model-Based Fault Diagnosis

2.3 Self-Tuning Estimation

References

Chapter 3: MEMS Heat Exchangers

3.1 Introduction

3.2 Fundamentals of Thermodynamics, Fluid Mechanics, and Heat Transfer

3.3 MEMS Heat Sinks

3.4 MEMS Heat Pipes

3.5 Two-Fluid MEMS Heat Exchanger

3.6 Need for Microscale Internal Flow Passages

Nomenclature

Greek Alphabets

Subscripts

References

Chapter 4: Application of Porous Silicon in MEMS and Sensors Technology

4.1 Introduction

4.2 Porous Silicon in Biosensors

4.3 Porous Silicon for Pressure Sensors

4.4 Conclusion

References

Chapter 5: MEMS/NEMS Switches with Silicon to Silicon (Si-to-Si) Contact Interface

5.1 Introduction

5.2 Bi-Stable CMOS Front End Silicon Nanofin (SiNF) Switch for Non-volatile Memory Based On Van Der Waals Force

5.3 Vertically Actuated U-Shape Nanowire NEMS Switch

5.4 A Vacuum Encapsulated Si-to-Si MEMS Switch for Rugged Electronics

5.5 Summary

References

Chapter 6: On the Design, Fabrication, and Characterization of cMUT Devices

6.1 Introduction

6.2 cMUT Design and Finite Element Modeling Simulation

6.3 cMUT Fabrication and Characterization

6.4 Summary and Conclusions

Acknowledgments

References

Chapter 7: Inverse Problems in the MEMS/NEMS Applications

7.1 Introduction

7.2 Inverse Problems in the Micro/Nanomechanical Resonators

7.3 Inverse Problems in the MEMS Stiction Test

Acknowledgment

References

Chapter 8: Ohmic RF-MEMS Control

8.1 Introduction

8.2 Charge Drive Control (Resistive Damping)

8.3 Hybrid Drive Control

8.4 Control Under High-Pressure Gas Damping

8.5 Comparison between Different Control Modes

References

Chapter 9: Dynamics of MEMS Devices

9.1 Introduction

9.2 Modeling and Simulation

9.3 Fabrication Methods

9.4 Characterization

9.5 Device Failures

Acknowledgments

References

Chapter 10: Buckling Behaviors and Interfacial Toughness of a Micron-Scale Composite Structure with a Metal Wire on a Flexible Substrate

10.1 Introduction

10.2 Buckling Behaviors of Constantan Wire under Electrical Loading

10.3 Interfacial Toughness between Constantan Wire and Polymer Substrate

10.4 Buckling Behaviors of Polymer Substrate Restricted by Constantan Wire

10.5 Conclusions

Acknowledgments

References

Chapter 11: Microcantilever-Based Nano-Electro-Mechanical Sensor Systems: Characterization, Instrumentation, and Applications

11.1 Introduction

11.2 Operation Principle and Fundamental Models

11.3 Microcantilever Sensor Fabrication

11.4 Mechanical and Electrical Characterization of Microcantilevers

11.5 Readout Principles

11.6 Application of Microcantilever Sensors

11.7 Energy Harvesting for Sensor Networks

11.8 Conclusion

References

Chapter 12: CMOS MEMS Integration

12.1 Introduction

12.2 State-of-the-Art inertial Sensor

12.3 Capacitance Sensing Techniques

12.4 Capacitance Sensing Architectures

12.5 Continuous Time Voltage Sensing Circuit

12.6 CMOS ASIC Design

12.7 Test Results of CMOS–MEMS Integration

12.8 Electrical Reliability Issues

References

Chapter 13: Solving Quality and Reliability Optimization Problems for MEMS with Degradation Data

Abbreviations

13.1 Introduction

13.2 Notations and Assumptions

13.3 Reliability Model

13.4 Numerical Example

13.5 Conclusions

References

Index

Materials and Failures in MEMS and NEMS

Scrivener Publishing 100 Cummings Center, Suite 541J Beverly, MA 01915-6106

Materials Degradation and Failure Series Studies and investigations on materials failure are critical aspects of science and engineering. The failure analysis of existing materials and the development of new materials demands in-depth understanding of the concepts and principles involved in the deterioration of materials The Material’s Degradation and Failure series encourages the publication of titles that are centered on understanding the failure in materials. Topics treating the kinetics and mechanism of degradation of materials is of particular interest. Similarly, characterization techniques that record macroscopic (e.g., tensile testing), microscopic (e.g., in-situ observation) and nanoscopic (e.g., nanoindentation) damages in materials will be of interest. Modeling studies that cover failure in materials will also be included in this series.

Series Editors: Atul Tiwari and Baldev Raj Dr. Atul Tiwari, CChem Director, R&D, Pantheon Chemicals 225 W. Deer Valley Road #4 Phoenix, AZ 85027 USA Email: [email protected], [email protected]

Dr. Baldev Raj, FTWAS, FNAE, FNA, FASc, FNASc Director, National Institute of Advanced Studies Indian Institute of Science Campus Bangalore 560 012, India Email: [email protected], [email protected]

Publishers at Scrivener Martin Scrivener([email protected]) Phillip Carmical ([email protected])

Copyright © 2015 by Scrivener Publishing LLC. All rights reserved.

Co-published by John Wiley & Sons, Inc. Hoboken, New Jersey and Scrivener Publishing LLC, Salem, Massachusetts. Published simultaneously in Canada.

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Library of Congress Cataloging-in-Publication Data:

Materials and failures in MEMS and NEMS / edited by Atul Tiwari and Baldev Raj.    1 online resource.  Includes bibliographical references and index.  Description based on print version record and CIP data provided by publisher; resource not viewed.  ISBN 978-1-119-08387-0 (pdf) – ISBN 978-1-119-08386-3 (epub) – ISBN 978-1-119-08360-3 (cloth : alk. paper) 1. Microelectromechanical systems–Design and construction. 2. Nanoelectromechanical systems–Design and construction. I. Tiwari, Atul, editor. II. Raj, Baldev, 1947- editor.  TK7875  621.381–dc23 2015027730

ISBN 978-1-119-08360-3

Preface

Manufacturing, diagnosis and treatment of biospecies, agriculture, energy and infrastructure, governance, security, etc., need sensors and devices based on well-grounded concepts, engineering and technology. Miniaturization demands new materials, designs and fabrication technologies. The decrease in the size and volume of devices has necessitated the incorporation of a high level of fabrication technologies. There is a priority need to address failures in micro- and nanodevices.

The invention of Microelectromechanical Systems (MEMS) and Nanoelectromechanical Systems (NEMS) fabrication technologies has revolutionized the science and engineering industry. It is estimated that market prospects for MEMS and NEMS will increase rapidly to reach $200 billion in 2025. The key to the success of MEMS and NEMS will be the development of technologies that can integrate multiple devices with electronics on a single chip. Among the technologies available so far, the fabrication of MEMS and/or NEMS has been predominately achieved by etching the polysilicon material. Novel materials and technologies are being explored to overcome the challenges in fabrication or manufacturing processes. In order to meet the ever-increasing demands of MEMS and NEMS, enormous amounts of research, applications and innovations have been explored and exploited. Most of the relevant information originating from such efforts is being treated as confidential or privileged, which seeds extensive barriers to the research, development and aspirational demands of these technologies.

This book includes chapters written by eminent experts in the area of MEMS and NEMS. The opening chapter of this book reviews various C-MEMS fabrication technologies involving patterning of polymeric precursors of carbon such as epoxy photoresists and sol-gel polymers, followed by pyrolysis to generate glassy or semicrystalline carbon. Another chapter discusses the origins of fault in such devices, related mathematical models and utilization of filters in fault diagnosis. Also, the authors have illustrated the structure of a multiple-model adaptive estimator and its application in fault diagnosis simulation. Another chapter provides an overview of the design of MEMS heat exchangers such as heat sinks, heat pipes and two-fluid heat exchangers. The formation of porous silicon devices by elec trochemical etching of silicon and the control over the porosity and pore size are discussed in a separate chapter. The use of such porous silicon devices as biosensors is thoroughly investigated by these contributors. Further, a chapter provides an overview on MEMS and NEMS switches using Si-to-Si contact. An interesting chapter discusses the design challenges during fabrication and failure analysis of cMUT devices. Investigators have compared the device fabrication by surface micromachining and wafer bonding techniques. Moreover, failure analysis of cMUT using various materials characterization techniques and their importance for successful device fabrication are also investigated.

A successive chapter investigates an effective approach to solve inverse problems in MEMS and NEMS. This chapter describes inverse problems in micro- and nanomechanical resonators and also the stiction test of MEMS and NEMS. Further, there is a chapter in the book dedicated to the control of ohmic RF-MEMS switches operating under different actuation modes, such as single pulse, tailored pulse, and tailored-pulse optimization methods, based on Taguchi’s technique of resistive damping; and the hybrid actuation mode, which is a combination of the tailored pulse, the resistive damping, and Taguchi’s optimization technique. Additional challenges involved in design methodologies, and available simulation packages to model and simulate MEMS devices are explored in a separate chapter. To develop MEMS devices and to understand the inception of fabrication defects, researchers have explored fabrication techniques such as surface micromachining and bonding silicon to glass. The use of different characterization techniques, such as visual, electrical and mechanical, for inspecting the defects in these devices has also been demonstrated. An independent chapter systematically investigates the buckling behavior of a typical micron-scale constantan-wire/polymer-substrate structure under electrical loading. Another crucial chapter discusses many important aspects of microcantilever sensors such as operation principles, fabrication of silicon and polymer microcantilevers, mechanical and electrical characterization, readout principles, applications of microcantilever sensors for vapor-phase chemical or gas detection, biosensing and agriculture applications; and nanogenerators for energy harvesting. A chapter in the book elaborates the inherent challenges encountered in CMOS–MEMS along with the possibility of integration at board and chip levels. This chapter also lists various circuit architectures being used in capacitance detection along with a detailed comparison on their merits and demerits. The final chapter proposes a mathematical model to determine strategies for preventive replacement and inspection for MEMS that are subject to multiple dependent competing failure processes as a result of degradation and/or shock loads.

We are confident that this book will constitute a large knowledge bank for students, research scholars and engineers who are involved in the research, development and deployment of advanced MEMS and NEMS for a wide variety of applications. To the best of the editors’ knowledge, such a book that addresses the developments and failures in these advanced devices has not yet been available to readers. Comprehensive expertise is mapped out and discussed in this book to advance the knowledge bank of readers in order to enable precise control over dimensional stability, quality, reliability, productivity and life cycle management of MEMS and NEMS.

The editors look forward to constructive suggestions and feedback for improving the next edition of this book on this important, relatively young subject of increasing importance and relevance.

Wishing you a purposeful and wonderful reading experience.

Atul Tiwari, PhD Baldev Raj, PhD August 4, 2015

Chapter 1

Carbon as a MEMS Material

Amritha Rammohan* and Ashutosh Sharma

Department of Chemical Engineering, Indian Institute of Technology, Kanpur, Uttar Pradesh, India

*Corresponding authors: [email protected]

Abstract

Carbon has become a popular material in microelectromechanical (MEMS) applications because of its versatile electrochemical and mechanical properties, as well as the numerous precursor materials and facile fabrication methods available. This review details various C-MEMS fabrication technologies, most of which involve the patterning of polymeric precursors of carbon such as epoxy photoresists and sol–gel polymers followed by their pyrolysis to create glassy or semicrystalline carbon pattern replicas. The structure and properties of glassy carbon, as well as the pyrolysis process and concurrent shrinkage, are also discussed in detail, as these directly affect the applicability of the carbon structures and devices. The integration of carbon structures in MEMS devices by means of surface modification and the incorporation of additives and fillers such as carbon nanotubes and carbon nanofibers to enhance the functional properties are also discussed.

Keywords: Carbon, C-MEMS, pyrolysis, volumetric shrinkage, MEMS integration, lithography

1.1 Introduction

Carbon is one of the most versatile materials in the periodic table. Due to its ability to form sp, sp2, and sp3 hybridized covalent bonds with various elements including itself, carbon-based compounds and materials are amongst the most adaptable materials available to us. The ability of carbon to form bonds with itself is manifested in the form of many allotropes of carbon including fullerenes, nanotubes, graphite, graphene, and diamond. Even within these allotropes, despite being all made of carbon, the properties such as electrical conductivity, hardness, and strength vary widely with allotrope due to different microstructures in terms of crystallite size, long-range order, anisotropy, etc. [1]. Amorphous or glassy carbon, in particular, has a wide window of electrochemical stability as well as high thermal conductivity and excellent biocompatibility, warranting its use in various electrochemical and biological applications [2]. Diamond-like carbon or DLC, another form of carbon, has superior tribological properties and wear resistance, and anisotropic carbon materials such as nanotubes and nanofibers can be leveraged for their unique and anisotropic electromechanical properties as well [2–4].

When this versatility in functional properties is combined with appropriate micro/nanofabrication techniques, carbon structures become highly viable as elements in micro and nano electromechanical systems (MEMS/NEMS). In order to create micro- and nanosized electromechanical structures such as actuators and microsensors from carbon, appropriate robust and facile micro/nanofabrication techniques have to be adopted. The methods to pattern carbon and its precursors into MEMS structures are divided, like other microfabrication techniques, into top-down and bottom-up techniques. Top-down techniques are subtractive processes such as reactive ion etching (RIE) and lithographic patterning with photons, electrons, or ions. Bottom-up or additive processes include sputtering, evaporation, and chemical vapor deposition (CVD) [5]. While top-down techniques create deterministic patterns with good shape and size control, bottom-up techniques result in increased functionality and have greater capability for three-dimensional (3D) patterns. Self-assembled structures that are formed with very little external guidance or direction also fall in the latter category of bottom-up techniques. Apart from strictly top-down and bottom-up techniques, many fabrication techniques include a combination of these two. For example, hierarchical structures can be achieved by top-down patterning of large-scale structures and bottom-up patterning of smaller, 3D features. Soft lithographic techniques such as micromolding and nanoimprinting are often considered a third classification of microfabrication techniques and have also been used successfully in the patterning of C-MEMS (Carbon MEMS) structures [6].

One process that facilitates the fabrication of amorphous or glassy carbon microstructures involves the pyrolysis of carbon-containing precursor molecules (usually polymers) that have been prefabricated into requisite micro/nanostructures (Figure 1.1). Pyrolysis or carbonization is the method of heating carbon-containing precursors to temperatures upward of 600 °C in an inert atmosphere such as nitrogen or argon to remove noncarbonaceous components in a material by volatilizing them into gaseous and hence removable compounds. This method, apart from allowing the creation of any required shape as long as appropriate formable precursors are used, also allows tweaking the properties of the final carbon micro/nanostructures by the rational use of various precursors with different functional groups. Appropriate precursors are those carbon-containing polymers that result in a high enough yield of carbonaceous residue and at the same time do not reflow when subjected to high temperatures during pyrolysis [2]. Thus, the methods to create glassy carbon MEMS structures can be decoupled into various methods to create microstructures in appropriate precursors and the pyrolysis processes (Figure 1.1).

Figure 1.1 Fabrication of Carbon MEMS structures using top-down, bottom-up and soft lithographic techniques.