Mems fundamental technology and applications

Devices, Circuits, and SystemsElectrical Solitons: Theory, Design, and Applications David Ricketts and Donhee Ham Electronics for Radiation Detection Krzysztof Iniewski Graphene, Carbo

FUNDAMENTAL TECHNOLOGY

Devices, Circuits, and Systems

Electrical Solitons: Theory, Design, and Applications

David Ricketts and Donhee Ham

Electronics for Radiation Detection

Krzysztof Iniewski

Graphene, Carbon Nanotubes, and Nanostuctures:

Techniques and Applications

James E Morris and Krzysztof Iniewski

High-Speed Photonics Interconnects

Lukas Chrostowski and Krzysztof Iniewski

Integrated Microsystems: Electronics, Photonics, and Biotechnology

Krzysztof Iniewski

Internet Networks: Wired, Wireless, and Optical Technologies

Krzysztof Iniewski

Low Power Emerging Wireless Technologies

Lukas Chrostowski and Krzysztof Iniewski

MEMS: Fundamental Technology and Applications

Vikas Choudhary and Krzysztof Iniewski

Nano-Semiconductors: Devices and Technology

Krzysztof Iniewski

Nanoelectronic Device Applications Handbook

James E Morris and Krzysztof Iniewski

Optical, Acoustic, Magnetic, and Mechanical Sensor Technologies

Novel Advances in Microsystems Technologies and Their Applications

Laurent A Francis and Krzysztof Iniewski

Nanoelectronics: Devices, Circuits, and Systems

Nikos Konofaos

Building Sensor Networks: From Design to Applications

Ioanis Nikolaidis and Krzysztof Iniewski

Embedded and Networking Systems: Design, Software, and Implementation

Gul N Khan and Krzysztof Iniewski

Medical Imaging: Technology and Applications

Troy Farncombe and Krzysztof Iniewski

Nanoscale Semiconductor Memories: Technology and Applications

Santosh K Kurinec and Krzysztof Iniewski

Nanoplasmonics: Advanced Device Applications

James W M Chon and Krzysztof Iniewski

MIMO Power Line Communications: Narrow and Broadband Standards, EMC,

and Advanced Processing

Lars Torsten Berger, Andreas Schwager, Pascal Pagani, and Daniel Schneider

Energy Harvesting with Functional Materials and Microsystems

Madhu Bhaskaran, Sharath Sriram, and Krzysztof Iniewski

Mobile Point-of-Care Monitors and Diagnostic Device Design

Walter Karlen and Krzysztof Iniewski

Integrated Power Devices and TCAD Simulation

Yue Fu, Zhanming Li, Wai Tung Ng, and Johnny K.O Sin

CMOS: Front-End Electronics for Radiation Sensors

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Vikas Choudhary

Contents

Preface xiEditors xviiContributors xix

SECTION I Breakthrough Technology

Chapter 1 Microsystems to Nano-Microsystems: A Technological Breakthrough 3

Daniel Hauden

Chapter 2 HfO2-Based High-κ Dielectrics for Use in MEMS Applications 21

Bing Miao, Rajat Mahapatra, Nick Wright, and Alton Horsfall

Chapter 3 Piezoelectric Thin Films for MEMS Applications 41

Isaku Kanno

Chapter 4 CMOS Systems and Interfaces for Sub-Deg/Hr Microgyroscopes 69

Ajit Sharma, Mohammad Faisal Zaman, and Farrokh Ayazi

Chapter 5 Bulk Acoustic Wave Gyroscopes 91

Houri Johari

Chapter 6 Mechanically Flexible Interconnects and TSVs: Applications in CMOS/MEMS

Integration 111

Hyung Suk Yang, Paragkumar Thadesar, Chaoqi Zhang, and Muhannad Bakir

Chapter 7 Modeling of Piezoelectric MEMS Vibration Energy Harvesters 131

Marcin Marzencki and Skandar Basrour

Chapter 8 Interface Circuits for Capacitive MEMS Gyroscopes 161

Hongzhi Sun and Huikai Xie

Chapter 9 Electromechanical Loops for High-Performance and Robust Gyroscope

SECTION II MEMS-Based Novel Applications

Chapter 10 Bulk Acoustic Wave Resonators for Mobile Communication Systems 205

Sumy Jose

Chapter 11 Wideband Ultrasonic Transmitter and Sensor Array for In-Air Applications 227

J R Gonzalez, Mohamed Saad, and Chris J Bleakley

Chapter 12 MEMS-Based Lamellar Grating Fourier Transform Spectrometers 249

Hongbin Yu, Guangya Zhou, and Fook Siong Chau

Chapter 13 Microelectromechanical Resonators for RF Applications 273

Frederic Nabki, Tomas A Dusatko, and Mourad N El-Gamal

Chapter 14 Rigid Body Motion Capturing by Means of Wearable Inertial and

Magnetic MEMS Sensor Assembly—From Reconstitution of the Posture toward Dead Reckoning: An Application in Bio-Logging 313

Hassen Fourati, Noureddine Manamanni, Lissan Afilal, and Yves Handrich

Chapter 15 Radio-Controlled Wireless MEMS Actuators and Applications 331

Mohamed Sultan Mohamed Ali and Kenichi Takahata

Chapter 16 Advanced MEMS Technologies for Tactile Sensing and Actuation 351

M Amato, Massimo De Vittorio, and S Petroni

Chapter 17 MEMS-Based Micro Hot-Plate Devices 381

Jürgen Hildenbrand, Andreas Greiner, and Jan G Korvink

Chapter 18 A Wireless Sensor Networks Enabled Inertial Sensor 401

Index 441

Chapter 1 by Daniel Hauden provides a comprehensive overview of MEMS technology and its evolution This chapter can be considered as an overview for the rest of the book Written by Dr Hauden, professor emeritus with the French University, who has been involved in this field virtually from its inception, the chapter offers readers an excellent snapshot of this field After a brief histori-cal perspective on the technological breakthroughs, a section rich in examples of microsystems that have been laboratory proven, as well as commercially successful, is introduced This is followed by

a section on the link between nanotechnology and the macroscopic world Eventually, the tion for a bottom-up approach for nanotechnology is discussed Throughout the chapter, readers are challenged with various scientific questions that need to be resolved, thereby paving the way for new applications For experienced readers, the chapter will serve as a refresher, while for students and researchers, it will serve as a platform to direct their research in the right direction and invigorate them with the right questions

motiva-Chapter 2 by Bing Miao et al discusses the need for research in the area of thin-film integrated passives as an alternative to discrete passives in an effort to save board space and improve electri-cal performance and system reliability Specifically, it discusses HfO2-based high-κ dielectrics for use in MEMS applications Additionally, the chapter is unique in that it is one of the few research works to discuss the long-term degradation (both performance and reliability) in electronics due to radiation

In general, silicon has been probably the most-studied material in the history of mankind and definitely for MEMS devices as well At the same time, functional materials, such as ferroelectric materials, have gradually been integrated into MEMS and they can give new functionality to simple microstructures Among them, piezoelectricity is very attractive for the application of microsensors and actuators Piezoelectricity has two characteristics, one is the piezoelectric effect, which means charge generation by an external stress or strain, and the other is the inverse piezoelectric effect, which is force generation by an external electric field These characteristics imply that piezoelec-tric materials are inherently sensors and actuators Therefore, unique functionality, especially in simple microstructures, can be created using piezoelectric materials that are integrated into MEMS Chapter 3 by Isaku Kanno from Kyoto University discusses such a possibility of developing piezo-electric MEMS This chapter can form a good basis for researchers and practicing engineers look-ing for alternative material for MEMS

A gyroscope is a sensor used to measure the angle or velocity of rotation From the days of the first silicon tuning-fork gyroscope introduced by Draper Labs in 1991, micromachined gyroscopes today constitute one of the fastest-growing segments of the microsensor market The application domain of these devices is quickly expanding from automotive to consumer and personal navigation systems Today, most micromachined gyroscopes use vibrating elements to sense rotation and are devoid of any rotating parts or bearings, making them suitable for batch fabrication using planar

processes and for potential integration with complementary metal–oxide–semiconductor (CMOS) circuitry Chapter 4 by Ajit Sharma et al introduces readers to the gyroscope and its implementation details through a case study of a mode-matched tuning fork gyroscope The first half of the chap-ter discusses the nonidealities associated with such a gyroscope and how they could be addressed potentially through circuits The second half of the chapter elaborates the case study with details of such an implementation This chapter sets the tone for Chapters 5, 8, and 9 on gyroscopes.

The performance of micromachined gyroscopes has significantly improved over the last two decades Since 1991, the resolution of micromachined gyroscopes, indicated by the random angle walk, has improved by a factor of 10 (Chapter 4) However, most of the improvements so far have come from the manufacturing, packaging, and, to some extent, signal-processing circuitry

A fundamental need has arisen to investigate structures that can provide orders of magnitude of improvement over current performance numbers Chapter 5 by Houri Johari presents bulk acoustic wave (BAW) gyroscopes that could be a potential solution for future gyroscopes Single-crystal silicon disk gyroscopes are designed to operate in their degenerate elliptic bulk acoustic modes with frequencies in the 1−20 MHz range This enhances the gyroscopes’ operational bandwidth

in the mode-matched condition compared to low-frequency (<100 kHz) flexural-mode gyroscopes

Operating gyroscopes in the mode-matched condition with a high quality factor (Q) enhances the

signal-to-noise ratio significantly and improves the performance of the gyroscopes This chapter gives an overview of BAW gyroscopes and would serve as excellent introductory material for those interested in pursuing this technology

Chapter 6 by Hyung Suk Yang et al begins by posing an excellent question The authors rightly observe that despite the fact that the MEMS market has grown substantially, the industry is domi-nated by a few powerhouses What prohibits this proliferation? And a follow-up question would be what enables widescale adoption of myriad MEMS devices? While the obvious answer is cost, it

is succinctly stated through what the Yole Development calls the MEMS Law—“One product, one process, one package” (MEMS Market Overview, 2010) This MEMS Law refers to the observed

trend that fabrication processes and packages needed by MEMS devices are so unique to those devices that both the fabrication process and packages cannot be standardized and therefore both need to be custom designed for each unique product Compared to the microelectronics industry where many small successful fabless companies exist, taking advantage of a dedicated foundry like the Taiwan Semiconductor Manufacturing Company (TSMC) to handle fabrication and packaging needs, many MEMS companies require a significant initial investment This sets the tone to dis-cuss possible solutions, and in this chapter, specifically, by leveraging new advances in flexible I/O technologies and through-silicon via technologies The authors believe that one can create a generic integration platform for state-of-the-art CMOS and arbitrary MEMS devices The chapter outlines the 3D integration of CMOS, and MEMS provides the performance of monolithic integration and the process simplicity of hybrid integration Key to exploiting all the benefits of 3D integration for CMOS and MEMS is leveraging advanced interconnect technologies such as flexible inter-connects and through-silicon vias In this chapter, the motivation and need for such interconnects are discussed along with an overview of challenges involved in the design and fabrication of such interconnects

Chapter 7 by Marcin Marzencki and Skandar Basrour addresses a very fundamental issue at the heart of this modern electronic gadget era, and that is device recharging What if a device never needs charging? Can this be accomplished? The authors claim that just as light energy has been successfully used as a source of energy, our environment is replete with pressure variations, structural deformations or mechanical vibrations, which can be harnessed to generate energy A scheme to harness such energy is called ambient energy harvesting This chapter then discusses harvesting the energy of ambient mechanical vibrations using piezoelectric MEMS devices What MEMS allows is miniaturization of such energy harvesters that can be integrated with electronics and hence open avenues for fully autonomous miniature systems The chapter discusses models for such a possible system and is rich in both theory and measurement of outlined theoretical models

The chapter also has a rich set of references at the end and can serve as an excellent reference for researchers in this field.

Chapter 8 by Hongzhi Sun and Huikai Xie first introduces basic knowledge about the interface circuits for capacitive MEMS gyroscopes The chapter is rich in theoretical analyses of the working principle of gyroscopes and their associated nonidealities In contrast to Chapter 4, the focus here

is more on capacitive sensing and associated circuitry The chapter deals with both continuous and discrete time sensing, and to some extent, a very general exposure on interfacing sensing circuits The readers of this chapter will benefit by having a solid understanding of how to analyze inter-face circuits, although specifically for capacitive interface gyroscopes, but this knowledge can be extended to any such interface MEMS circuitry

Chapter 9 by Vikas Choudhary et al presents a unique viewpoint for ultimately creating a highly robust and high-performance microsystem, with a capacitive vibratory-type MEMS gyroscope as a case in point The viewpoint offered in this chapter is essentially to harness the advances made in the field of circuit design and signal processing to create electromechanical loops The nonidealities

of the sensor can be sensed through the electronic signature, processed and then finally electrical signals can be issued to the sensor to correct such behavior The approach can, in fact, be extended

to issue electronic signals to the sensor to mimic certain qualified behavior, which can then be indicative of the health of the system, thereby creating a platform for more robust systems This chapter concludes with a plethora of applications that such a robust gyroscope system has spawned Readers can derive significant insights into creating high-performance inertial systems

BAW resonators have been researched for several decades now They have shown great promise and are also making their presence felt commercially, particularly in the field of wireless Lately a major trend has been the replacement of conventional RF filters at the front end of the receiving or transmitting chain for gigahertz wireless applications by BAW filters, particularly because of a high

Q (selectivity) steep transition band Chapter 10 by Sumy Jose begins with an overview of the basics

of BAW device physics and then goes on to explain such devices in greater detail This particular chapter can serve as a good tutorial for those just being initiated in this field The chapter further has

an exhaustive set of references that can be used for further reading and research

Chapter 11 by J R Gonzalez et al presents a unique application of creating ultrasonic receiver arrays using MEMS sensors In particular, this chapter presents the results of the authors’ research

on the use of piezoelectric transducers and MEMS sensors in wideband in-air ultrasonic location applications with a focus on low cost, low power, and wideband The chapter elaborates on how conventional technology cannot meet such a demand, thereby presenting a modification process for ultrasonic transmitters resulting in a significant increase in piezoelectric transducer bandwidth Theory and experimental results are presented and validated and eventually the chapter asserts a new direction for local positioning systems (LPS) For industry researchers and entrepreneurs, this chapter can serve as a reference for taking such MEMS-based applications to their commercial end.Chapter 12 written by Hongbin Yu et al presents another novel application of MEMS technol-ogy Optical spectrometers are very important instruments in the field of metrology However, they need to be miniaturized and are required to operate under harsh environments This has been the main driving force for optical MEMS-based spectrometers This chapter introduces readers to sev-eral designs of miniaturized field-applicable FTIR microspectrometers based on lamellar gratings These designs are implemented using silicon-on-insulator (SOI) micromachining and are shown to have lighter weight, lower device cost, and a more compact configuration Readers of this chapter will get a full preview of the state of the art in MEMS-based spectrometers and the challenges asso-ciated with commercializing this application

Chapter 13 by Frederic Nabki et al is on microelectromechanical resonators and their tion with conventional circuitry on a chip to create highly compact subsystems The chapter focuses mainly on RF applications The chapter begins with a primer on MEMS resonator basics and does a thorough job of defining all the performance parameters, modeling, nonlinearity, and so on, that are associated with such devices The chapter then elaborates on a few applications that such resonators

are enabling, for example, filters and oscillators Additionally, the chapter has a full section on MEMS resonators and concludes with a case study on a resonator-based complete system This chapter thoroughly deals with MEMS resonators, and readers will enjoy the completeness of mate-rial This can further serve as a platform for researchers and students in this field.

Rigid-body motion capture has myriad applications and Chapter 14 addresses this by proposing

a robust alternative approach to estimate the movement patterns (attitude or orientation) of a rigid body, which represents the animal body Further, to achieve this, the authors of the chapter, Hassen Fourati et al., propose a wearable inertial and magnetic MEMS sensor assembly based on a 3-axis accelerometer, a 3-axis magnetometer, and a 3-axis gyroscope (inertial measurement unit) Detailed results of this application are presented and offer entrepreneurs a platform to study the performance

of such MEMS-based systems that can be potentially commercialized

MEMS for drug-delivery applications have attracted significant interest Implantable MEMS devices for this application are aimed at enabling the controlled release of drugs locally at dis-eased sites through miniaturized devices, offering a more effective therapy compared with conven-tional methods for systemic drug administration that can have a negative impact on the entire body Chapter 15 by Mohamed Sultan Mohamed Ali and Kenichi Takahata focuses on recent research progress in wireless microactuators to enable applications like the above The chapter is complete

in itself in the sense that it has a detailed description of such a novel device and its applications.The contrasting challenge of emulation of the human sense of touch, on the one hand, and accu-rate reproduction of haptic feedback, on the other hand, presents a challenge in the field of robot-ics Chapter 16 by M Amato et al discusses the use of MEMS technology for tactile sensing and actuation The chapter begins with the human sense of touch, which inspires and drives the design

of tactile systems Following this, a review of the state of the art in MEMS technology for tactile sensors and actuators discusses their principle of operation, advantages, and drawbacks with an emphasis on soft MEMS technology and biomimetic approaches

Devices with an integrated heater element—micro hot plates—form another family of MEMS devices, sensing orders of several hundreds of degree Celsius Chapter 17 by Jürgen Hildenbrand

et al elaborates the scheme for such a MEMS-based micro hot-plate device The chapter begins with a review of the state of the art of such devices and then discusses the design process for such hot plates Later in the chapter, these devices are characterized and the results are discussed in detail At the end of the chapter, a few applications such as the use of hot plates in metal-oxide-based gas sensors and thermal emitters are also elaborated upon

Chapter 18 by Yao-Chiang Kan talks about creating IMUs (inertial measurement units) with integrated wireless circuitry to enable convenient and continuous monitoring This chapter begins with the basic theory of inertial navigation, the error characteristics of MEMS IMUs, and the effects

of these errors on a calculated position Radio frequency (RF) technology is then introduced with an emphasis on antenna issues for different applications, followed by a description of a wireless sensor network (WSN)-enabled inertial sensor node (ISN) developed by the author Later in the chapter, applications are discussed The chapter essentially provides an application-based view of the main components of a WSN-enabled ISN This chapter can serve as a good reference for practicing or application engineers who are involved in this field

Chapter 19 by Sylvain Ballandras et al discusses passive acousto-electric devices and their applications in wired and wireless systems Passive acousto-electric devices have been extensively used for a long time in various RF applications Of all these, the possibility of developing sensors and associated systems using these devices has been widely investigated and has yielded numerous academic as well as industrial developments Different strategies can be implemented for probing these sensors, based on time-domain analysis or using spectrum techniques depending on the sen-sor nature In this chapter, the authors introduce the basic principles of RF acoustic devices and the various structures usually implemented for sensors Several examples illustrate the implementation

of these devices and the focus is then on the different electronic systems devoted to sensor operation control The authors also present the state of the art concerning accuracy, resolution and stability,

interrogation distance, and long-term robustness of these systems, with a discussion on the further development of such devices and their present and future applications.

Finally, we would like to acknowledge the help extended by all the contributing authors Vikas Choudhary would also like to acknowledge S Karthik and Farhad Vazehgoo at Analog Devices for their encouragement during the course of compiling this book Last, our sincere thanks go to CRC Press and its staff for hours of editing work that went into making this effort come out as a book.MATLAB® is a registered trademark of The MathWorks, Inc For product information, please contact:

The MathWorks, Inc

3 Apple Hill Drive

Editors

Vikas Choudhary is currently a senior manager of the MEMS and Sensor Technology Group at

Analog Devices He is involved in the design and management of products for inertial MEMS Additionally, he manages a team of engineers involved in the design of high-performance precision analog-to-digital converters

Vikas has more than 18 years of experience in the semiconductor industry In his career, he has been involved in the design of both circuits and systems for high-speed gigabit signaling for chip-to-chip interconnects He has led designs of advanced clock and data recovery systems and equalization schemes for receivers and transmitters He was also the architect and lead designer for several RFIC subsystems such as 802.16e and 802.11n He has held various management and design positions at PMC-Sierra Inc., Texas Instruments, and STMicroelectronics He earned his master’s in signal processing from the University of California, Los Angeles, and has three issued patents His current research interests are in the field of applied signal processing for high-performance analog circuits and systems He can be reached at vikas.choudhary@analog.com

Krzysztof (Kris) Iniewski is managing R&D at Redlen Technologies Inc., a start-up company in

Vancouver, Canada Redlen’s revolutionary production process for advanced semiconductor als enables a new generation of more accurate, all-digital, radiation-based imaging solutions He is also the president of CMOS Emerging Technologies Research (www.cmosetr.com), an organization for high-tech events covering communications, microsystems, optoelectronics, and sensors

materi-Dr Iniewski has held numerous faculty and management positions at the University of Toronto, University of Alberta, Simon Fraser University, and PMC-Sierra Inc He has published more than

100 research papers in international journals and conferences He holds 18 international patents granted in the United States, Canada, France, Germany, and Japan He is a frequently invited speaker and has consulted to multiple organizations internationally He has written and edited sev-eral books for Cambridge University Press, Wiley, CRC Press, McGraw-Hill, Artech House, and Springer His personal goal is to contribute to healthy living and sustainability through innovative engineering solutions He can be reached at kris.iniewski@gmail.com

Mohamed Sultan Mohamed Ali

Micro and Nano Technology Research Group

Universiti Teknologi Malaysia

Johor, Malaysia

M Amato

Istituto Italiano di Tecnologia and

Dipartimento di Ingegneria dell’Innovazione

Università del Salento

Lecce, Italy

Farrokh Ayazi

School of Electrical and Computer Engineering

Georgia Institute of Technology

Emile Carry

FEMTO-STUniversité de Franche-Comté (UFC)Besançon, France

Fook Siong Chau

Department of Mechanical EngineeringNational University of SingaporeSingapore

Luc Chommeloux

FEMTO-STUniversité de Franche-Comté (UFC)Besançon, France

Vikas Choudhary

MEMS & SensorsAnalog DevicesBangalore, India

Nicolas Chrétien

SENSeOR SASParc de Haute Technologie du Font de l’OrmeMougins, France

andSENSeOR (R&D)Besançon, France

William Daniau

FEMTO-STUniversité de Franche-Comté (UFC)Besançon, France

Massimo De Vittorio

Istituto Italiano di Tecnologia

and

Dipartimento di Ingegneria dell’Innovazione

Università del Salento

Department of Automatic Control

GIPSA-LAB Grenoble, France

School of Computer Science and Informatics

University College Dublin

Saravanan Kamatchi

MEMS & SensorsAnalog DevicesBangalore, India

Yao-Chiang Kan

Department of Communications Engineering

Yuan-Ze UniversityTaoyuan, Taiwan

Deva Phanindra Kumar

MEMS & Sensors

Simon Fraser University

Burnaby, British Columbia, Canada

David Rabus

FEMTO-STUniversité de Franche-Comté (UFC)Besançon, France

andSENSeOR (R&D)Besançon, France

Meddy Vanotti

FEMTO-STUniversité de Franche-Comté (UFC)Besançon, France

Hyung Suk Yang

Georgia Institute of Technology

Atlanta, Georgia

Hongbin Yu

Department of Mechanical EngineeringNational University of SingaporeSingapore

Mohammad Faisal Zaman

Section I

Breakthrough Technology

The new tools generally ensure a link with nanotechnology (technology capable of elaborating objects structured on the scale of the nanometer) and the macroscopic real world Nanotechnologies lead to creating infinitely local functions using either sculpture by manipulating atoms, molecules,

or molecular assembly (the bottom-up way) They are approachable to the users through a ous line as nano–micro–meso–macro systems, ensuring coherent and additional set of useful func-tions from nano to real world

continu-1.1 FROM MICROELECTRONICS TO MICROSYSTEMS

The microelectronics developed on the concept of C-MOS transistor and on planar manufacturing technology allow for an automatic realignment of various technological layers implemented during circuit integration

1

CONTENTS

1.1 From Microelectronics to Microsystems 31.1.1 Realization of Micromechanisms with Mobile Parts 41.1.2 Increase of Mechanical Couple and Power in Micromechanisms 51.1.2.1 LIGA Techniques 61.1.2.2 Scratch Drive Technique 61.1.3 Main Fields of Application of Microsystems 61.1.3.1 Precursor Domains (up to 2000) 61.1.3.2 Exploring Applications of Microsystems Combined with

Nanotechnologies 71.2 Microsystems: A Link between Nanotechnologies and the Macroscopic World 141.3 Bottom-Up Nanotechnologies: Future of Nanoelectromechanical Systems 151.4 Conclusion and Perspectives 16Acknowledgments 18References 18

Microelectronics evolved toward ultra-miniaturization (known as nanoelectronics) Collective manufacturing in parallel (batch processing) also allows for a decrease in the manufacturing cost.

In the 1980s, miniaturization of mechanical and electromechanical components, for instance,

in the watch industry and micromechanical systems, was traditionally fabricated in line, was more expensive, and was certainly improved from the point of view of their precision of manufacturing and assembly

The idea to design and fabricate mechanical functions by using the technologies of electronics

is not new Indeed, from 1967, Bell Laboratories proposed the structure of an electromechanical transistor with a vibrating beam resonator, which is the first known electromechanical microcom-ponent [1] However, an important technological effort was necessary to integrate mobile parts in the manufacturing processes of the microelectronics

1.1.1 Realization of MicRoMechanisMs with Mobile P aRts

To elaborate micro-mechanisms with parts in movement, the manufacturing process needs to bine surface and volume machining In 1978, K.E Beam published the process of chemical etching

com-of anisotropic silicon crystal to obtain monolithic structures in three dimensions (Figure 1.1) This concept was generalized in 1982 by Professor Kurt E Petersen to promote silicon as the best mate-rial in micromechanics [3]

Microsensors for accelerometry and gyrometry were then fabricated from silicon wafers by bulk micromachining as shown in Figure 1.2, which represents a two-axis gyrometer, designed in a bulk silicon wafer The three corresponding signals are detected either by electrical detection through a capacitive measurement or by an optical detection of three beam vibrations (two for measurement and the third to prove the validity of the result) This structure is directly machined from the silicon wafer with a deep reactive ionic etching (DRIE) process

During the 1980s, several laboratories proposed integration of a local chemical etching of thin layers of soft silica (sacrificial layer) to release the mechanical mobile parts of MEMS (microelec-tromechanical systems) (suspended beams, bridge, etc.) These new processes then paved the way to numerous electromechanical applications of microsystems in the field of sensors and microactua-tors The historic example (Figure 1.3) is the all-silicon microengine, manufactured in 1989, at the

FIGURE 1.1 A three-dimensional microstructure manufactured by the process of bulk chemical etching of

silicon to obtain the sensitive element of a three-axis accelerometer Four very thin arms of silicon separately suspend three inertial masses in silicon (Adapted from J.C Jeannot et al., Micro-accéléromètre intégré 3 axes,

Microcapteurs et microsystèmes intégrés Nano et Micro Technologies, 1(1), 33–54, 2000.)

University of Berkeley, with a diameter of 150 µm [5] The sequenced electrostatic strengths pull the rotor, but the mechanical torque and the mechanical power are extremely weak, lower than the tenth

of micro-Newton-meter and the micro-Watt This is the main limitation of silicon microactuators and electrostatic microengines for applications in the mechanisms of very small sizes

1.1.2 incRease of Mechanical couPle and PoweR in MicRoMechanisMs

The increase of couple and mechanical power is obtained either by increasing the electrostatic strength (higher thickness) or by using active materials to induce an important mechanical strength

or a large deformation (piezo, giant magnetoresistance effect (GMR), etc.)

FIGURE 1.2 The two-axis gyrometer is a free suspended structure with two arms clamped on the silicon

frame The sensing part consists of three double beams vibrating at the same frequency in a flexure mode in the plane When it is rotating around the axis, the vibration energy is transferred in an orthogonal vibrating mode out of the sensor plane (Adapted from J Maisonnet, Optimisation et realisation d’un micro-gyromètre deux axes à poutres vibrantes en silicium, these de Doctorat Université de Franche-Comté, 20 novembre 2009.)

FIGURE 1.3 Rotary electrostatic engine side electrostatic excitement An electric field in the order of 100 V

runs the rotor The fixed electrodes are periodically deposited on the stator and are electrically driven by a sequence of periodic electric signals.

1.1.2.1 LIGA Techniques

The couple and the power, thus the electrostatic strength, are proportional on the active surface of electrodes We increase this surface by increasing the thickness of the drivers (the stator and the rotor) Several techniques are available in the industry to increase the form factor (the thickness/width ratio) of the driver electrodes Technology using thick (>50 µm) electrosensitive resins [poly (methyl methacrylate) (PMMA)], which are insulated with hard x-rays, is called “technique LIGA”

[Lithographie, Galvanoformung, Abformung (lithography, electroplating, and molding)] or

photo-sensitive thick resins (SU-8, for instance) illuminated by the traditional microelectronics UV light, called poor man’s LIGA technique These techniques are generally completed by a step of electro-lytic nickel metal deposit (and often another step of micromolding) (Figure 1.4)

Remark: The poor man’s LIGA technique is completely compatible with standard technology processes and equipments of microelectronics and, thus, much less expensive than the LIGA tech-nique using sunstroke by x-rays from a synchrotron ring machine

Several European and American manufacturers use this technique to applications such as forms of micro-optics, micromechanics components, and chemical microreactors for catalysis

plat-1.1.2.2 Scratch Drive Technique

This example shows the evolution of ideas in micromechanical systems where we turn to good properties of friction to activate the rotor (previously, the frictions were prohibited in mechanics).Another type of silicon micromotors with friction (called scratch drive), completely realized with a microelectronic technology polysilicium, is shown in Figure 1.5 It combines the electrostatic command of microfingers with their friction on the stator, which then pulls the rotor

This technique allows for realization of distributed microactuators to applications such as tion control, microconveyor of very small parts for microassembly lines, and adaptive micro-optics The most spectacular demonstrator is a nanodrone with vibrating wings [7]

vibra-1.1.3 Main fields of aPPlication of MicRosysteMs

1.1.3.1 Precursor Domains (up to 2000)

The contribution of microtechnologies in low-cost consumer products was rapid in the following three branches of industry:

• Subsystems of computing peripherals such as the heads of printers (inkjet systems) and the reading and writing heads of hard disks

FIGURE 1.4 (a) Micromotor crown with electrostatic command realized in poor man’s LIGA and several

stages of electrolytic nickel deposits (b) High-aspect-ratio capacitive electrodes with 10-µm-thick

electro-formed nickel (Adapted from S Basrour et al., IEEE Digest of Tech Papers for the Int Conf on Solid State

• Wrist watches with the microsystem energy source and storage Kinetic Seiko model and today with additional functions such as altimeter, pedometer, heart rhythm controller, ten-siometer-integrating accelerometers, and pressure microsensors.

• Automobile equipments for the automated control of engines’ electronic gas jet and for safety in vehicles (airbag system and trim control of cars and buses)

In the automobile domain, microsystems such as airbag systems and pressure sensors are usually used for injection of fuel in engines in vehicles (Figures 1.6 and 1.7) [8]

1.1.3.2 Exploring Applications of Microsystems Combined with Nanotechnologies

With regard to the success of the previous applications, the other branches of industry quickly took into account the concepts and technologies of miniaturization and systems integration replacing the current conception of systems (scaling-up) by a multiplicative approach from elementary microsys-tems (numbering-up)

Another approach is to have a cloud of microsystems disseminated or distributed (sensors + ators + communication circuits) to control processes or the environment

actu-(b) (a)

E

FIGURE 1.5 (a) Micromotor of type scratch drive (500 µm) according to P Minotti The rotor is driven by the friction of 18 microfingers scratching the stator and allowing rotation around the central axis The scratch drive principle is illustrated in (b).

FIGURE 1.6 Sensor of shock activating for the inflating of the pillow of the airbag The part in black is the

shock sensor (SensoNor A/S).

Three interesting industrial domains in microsystems are: telecommunications, engineering of chemical processes, and biological and medical applications up to ambulatory systems.

In telecommunications, increasing the electromagnetic and optical frequency created new needs because there was routing of millions of communications at a time New microsystems are proposed for switches or for massive route planners in radiofrequency (RF) or micro-opto-electromechanical systems (MOEMS) (Figure 1.8)

Integrated fast electro-optic modulators up to 40 GHz have been commercially available in LiNbO3 technology for several years Today, a new concept of modulation combines the nano-structure of photonic crystal with integrated technology to modulate and control frequency-band selection

Figure 1.9 is an example of a prototype realized on the Ti-LiNbO3 optical waveguide with a photonic crystal grooved in niobate by the focused ion beam (FIB) process (Figure 1.9a and b) [10].Moreover, because the optical and the high-frequency acoustic wavelengths are similar, new opto−acoustic systems could be developed for communications (and for sensing) Here is an exam-ple of a phononic (acoustic) bandgap (BG) which selects the frequencies propagating on a surface acoustic wave (SAW) sensor on a quartz crystal (Figure 1.10) Figure 1.11 represents the SAW

FIGURE 1.7 Microsensor of pressure for the injection jet of fuel (SINTEF).

FIGURE 1.8 Wave Star TM lambda router with aluminum micromirrors on silicon (Adapted from J.E

Ford et al., Solid State Sensors and Actuators Workshop, pp 11–12, 1998.)

FIGURE 1.9 (a) Photonic crystal in LiNbO3 (b) LiNbO 3 tunable photonic crystal optical modulator.

FIGURE 1.10 SAW phononic crystal.

0.35 0.3 0.25 0.15 0.05

Distance (μm)

0 0.1 0.2

15 10 5 0

0.5 0.4 0.3 0.2 0.1 0

FIGURE 1.11 Frequency response of SAW BG at 800 MHz.

propagation at 800 MHz scanned by a laser probe and the amplitude wave profile, which shows the

BG acting as an acoustic mirror This constitutes a phononic crystal [11]

If we combine an optical waveguide integrated in LiNbO3 with a phononic crystal (it is also the photonic crystal!), a phoXonic crystal filter-modulator is designed (Figure 1.12) The low cost opto-electronic systems and microrouters will increase ultrafast telecommunications from networks to home computers In chemical, biochemical, and environmental domains, MEMS can be a producer

of materials and/or sensors

Two complementary concepts guide the microsystems for chemical processes: either the turized model of different functions (separation, filtering, thermal heat exchanger, reactor, etc.) acts

minia-as a microreactor model of the real one or a combination of multiple microreactors in parallel to obtain, by multiplication (numbering-up), the volume of synthesized material

It is then possible, with millions of identical microreactors, each delivering 1 mg of material,

to obtain simultaneously 1 kg of material It is an argument of undeniable security for dangerous materials, which are produced in very big factories today then forwarded by ground or shipping transportation

The microsystems for the processes of synthesis and combinatorial analysis are very ing because the kinetics is fast and time for analysis is extremely short The number of operations

promis-is then considerably increased by numbering-up Thpromis-is promis-is very important in the research for new medicines Here is an example on protein crystallization to identify each one by a spectrometric technique This method combines the thermodynamic conditions in parallel microfluidic channels

in order to separate different proteins (Figure 1.13) This method is in progress to implement a throughput screening machine with a recognizing spectrometric technique

high-The first 10 years of the twenty-first century were devoted to new technologies for local diagnosis The idea is to use minimal invasive or not invasive systems through the natural ways

of the human body Examples are flexible, intelligent, sub-millimeter-length endoscopes with tools for diagnosis and/or adapted localized therapy, or more recently, autonomous pills The c-MUTS is typically one acoustic MEMS to image tumors or cracks along the natural body tubes (Figure 1.14)

Another example is an intradermal medical injector made from an electroformed needles carpet

on silicon (or glass substrate) that enables injection of the medicine several times quickly and lessly through the derma (Figure 1.15)

pain-The complete system was tested on pig skin, and the material diffusion is compared with one standard needle for vaccine (Figure 1.16)

In energy sources applications, projects on microfuel cells combine the nanotechnologies and the MEMS technologies Here is an example of PEM (proton exchange membrane) hydrogen fuel cells developed in France [16,17] Figure 1.17 describes the hydrogen fuel cell where the ionomer

Guide d’onde optique

Crystal phoXonic Transducer

Luniere

+V

FIGURE 1.12 Acousto-optic modulator based on phononic and photonic crystal (called phoXonic

crys-tal) at 800 MHz (Adapted from V Laude, Phononics, phononic crystals, and beyond, IEEE International

membrane (inorganic skeleton) is a thin membrane of porous silicon obtained by a standard MEMS technology process with an electrochemical etching in ethanol/HF providing nanometric porosities (Figure 1.18).

This solid ionomer skeleton is filled with NAFION that is the proton donor of the fuel cell NAFION

is a fluoropolymer shown in Figure 1.19 Exchange of hydrogen/protons is on the surface of the mer In order to increase the electrical current, NAFION spheres are filled with grafted chains bearing polymers (entangles trisilane) on microporous gels so that the pores are less than 2 nm Finally, the elementary fuel cell is plated with gold to form its electrodes (Figure 1.20) The first results obtained are shown in Figure 1.21 for one elementary cell On account of the collective fabrication process,

poly-it is possible to combine several elementary fuel cells in parallel to increase the current denspoly-ity or

in series to increase the voltage These first results lead to expectation of more improvements on performance

Injection of crystallizing agent

FIGURE 1.13 Protein crystallizations in fluidic multimicrochannels in parallel (Adapted from K Dhouib

et al., Lab on a Chip 9(10), 1412–1421, 2009.)

FIGURE 1.14 Principle of a cMUT exploiting the fundamental flexural mode of an Si plate actuated by a DC-bias

voltage plus an AC excitation (Adapted from O Arbey et al., 8th International Workshop on Micromachined

(a) (b) (c)

FIGURE 1.15 (a) Array of microneedles (b) Elecroformed needles (c) Complete system on silicon substrate.

Needles carpet

Standard needle Diffusion metoprolol

0 5 10 15 20

FIGURE 1.17 Principle of the PEM hydrogen fuel cell.

FIGURE 1.18 Porous silicon of the ionomer membrane (30 nm of porosities).

FIGURE 1.19 NAFION structure and chemical composition.

FIGURE 1.20 Elementary fuel cell under electrical tests (4 mm2 as the active surface).

1.2 MICROSYSTEMS: A LINK BETWEEN NANOTECHNOLOGIES

AND THE MACROSCOPIC WORLD

This distributed microsystems in matrix was generalized for the DNA chips, with massively parallel elements of bio-detection, first developed by the Affymetrix company [18] In these matrices, each element (oligonucleotides) has a lateral size close to nanometric dimension (Figure 1.22)

This first example shows the necessity of having a strategy of connections between tures and the real world All the micro–nano systems of the published nanosciences have the same

nanostruc-Current density (mA/cm 2 )

10 20 30 40 50 60 70

FIGURE 1.21 Voltage and current density of the fuel cell.

Gene Chip ® probe array Hybridized probe feature

Single standard, fluorescently

labeled DNA target Oligonucleotide probe

24 μm

Each probe feature contains millions of copies of a specific oligonucleotide probe Over 200,000 different probes complementary to genetic information of interest

Image of hybridized probe array 1.28 cm

FIGURE 1.22 Gene chip arrays from Affymetrix.

approach to bind the atomic or molecular part (nanometrics) with the final application by one or several microsystems generally distributed in matrix to make either actions or detection in parallel.

A significant example is the concept of MEMS memory Millipede by IBM, which corresponds

to a microadvanced matrix for thermoelectric reading/writing with a high density The apex of each tip has a radius on the scale of a few nanometers allowing data to be written at extremely high den-sities (much greater than 1 Tb/in²) In addition to the cantilevers, the array chip also carries eight

thermal sensors that are used to provide x/y positioning information for closed-loop operation of the

microscanner (Figures 1.23 and 1.24) [19] This is one of the first and complete examples of system

Millipede Highly parallel, very dense AFM data storage system 2D cantilever array chip

Multiplex driver

Storage medium (thin organic film)

x

FIGURE 1.23 MEMS memory Millipede scanner principle by IBM.

FIGURE 1.24 2D-Cantilevers chip array command by two multiplex systems: (a) chip array and (b) cantilever

details (IBM company).

Several research teams of IBM manipulated atoms one by one to build a new structure like an atomic sculpture (Figure 1.25) The size of the individual component is close to ultimate limits, but the sculpture process by STM manipulation is slow and expensive, thus only applicable to individual specific components [20,21] To reach a bottom-up atomic process, manufacturing must be made in large scale by chemical reactions, which is called molecular assembly on a structured surface This

is extensively studied in a large number of universities and company laboratories at present There are examples from FEMTO-ST Laboratory (France) [22] first to explore electric switch properties (Figure 1.26a) and second to try to move a molecule along an atomic step (Figure 1.26b) These nanostructure experiments need a theoretical evaluation of the compatibility between molecules and structured surfaces At the nano level, the simulation is done with an ab initio software (Figures 1.27 and 1.28)

1.4 CONCLUSION AND PERSPECTIVES

The different examples show the variety of micro- and nanotechnologies which, organized between them, pose new scientific questions to resolve and open the way to innovative applications

FIGURE 1.25 Atomic structures made with an STM manipulating individual atoms (a) Thirty-five

xenon atoms on nickel (Adapted from D.M Eigler, E.K Schweizer, IBM Research Division, Almaden

Research Center, CA, USA.) (b) Forty-eight iron atoms on (111) Cu (Adapted from After Nanosciences— Nanotechnologies Report, Académie des Sciences and Académie des Technologies—rst n ° 18, Ed Tec & Doc Lavoisier, 18 April 2004.)

non-FIGURE 1.26 Experimental results of 2,4,6-tri(2′-thienyl)-1,3,5-triazine on Si–B.

Therefore, in the microsystems, even if the models remain, based on the laws of classical physics and mechanics, the extreme miniaturization leads a new approach of modeling On the one hand, the properties of surfaces are more dominating as the volume of the system is small and, on the other hand, very weak sizes impose a very high coupling of the physical phenomena between them Hence, to model microsystems, it is not possible anymore to optimize the various effects by simple models of linear superimposition, but it is necessary to resolve simultaneously all the generally not linear coupled models: electrical, mechanical, thermal, fluidic, and so on This is called multiphys-ics and multiscaling modeling.