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FUNDAMENTAL TECHNOLOGY

AND APPLICATIONS

Edited by

VIKAS CHOUDHARY

KRZYSZTOF INIEWSK I

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Dedicated to Anu, Aryaman, Anushka, and my parents

Vikas Choudhary

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ix

Contents

Preface...............................................................................................................................................xi

Editors............................................................................................................................................xvii

Contributors....................................................................................................................................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

System Design.......................................................................................................... 183

Vikas Choudhary, Abhinav Dikshit, Anjan Kumar, Deva Phanindra Kumar,

Saravanan Kamatchi, and Nemai Biswas

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x Contents

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

Yao-Chiang Kan

Chapter 19 Passive Radio-Frequency Acoustic Sensors and Systems for Wired

and Wireless Applications........................................................................................ 417

Sylvain Ballandras, Gilles Martin, Jean-Michel Friedt, Victor Plessky,

Virginie Blondeau-Pâtissier, William Daniau, Thomas Baron, Luc

Chommeloux, Stéphane Tourette, Jean-François Leguen, Bruno François,

Christophe Droit, Meddy Vanotti, Marc Lamothe, David Rabus, Nicolas

Chrétien, and Emile Carry

Index.............................................................................................................................................. 441

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xi

Preface

The microelectromechanical systems (MEMS) industry has seen explosive growth over the last

decade. This industry has seen proliferation in various technologies and applications alike. There

is not a single book that can present a unique view of this landscape and this book is no different.

However, this book serves the purpose of being eclectic in its selections from authorities in their

respective fields. This book has 19 chapters, roughly divided into two broad categories. Chapters

1–9 in the technology section discuss new MEMS devices, whereas Chapters 10–19 in the applica￾tions section dwell upon novel MEMS-based applications. Each chapter is complete in itself and

can be read in isolation or in conjunction with other chapters of the book. Below we give a brief

overview of the chapters to guide readers for a quick selection of the topic of their choice.

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 motiva￾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.

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

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xii Preface

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.

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Preface xiii

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 integra￾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

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xiv Preface

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,

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