Page 20 - An Introduction to Microelectromechanical Systems Engineering

Preface to First Edition

I stood a few years ago before an audience at a customer’s facility explaining the
merits of micromachining technology. The small conference room was packed, and
all ears were attentive. Everyone was eager to learn about this mysterious buzz-
word, “MEMS.” Many in the audience were nodding in a sign of comprehension,
but the gazed looks on many faces betrayed them. This experience is not unique;
rather, it repeats itself frequently in auditoriums around the world. The technology
is simply too broad to be explained in a short lecture. Many technical managers,
engineers, scientists, and even engineering students with little or no prior experience
in microelectromechanical systems are showing a keen interest in learning about
this emerging technology. This book is written for these individuals.
I sought in this book to introduce the technology by describing basic fabrica-
tion processes and select examples of devices and microsystems that are either com-
mercially available or show great promise in becoming products in the near
future—practical examples from the “real world.” The objective is to provide a set
of representative cases that can give the reader a global understanding of the tech-
nology’s foundations and a sense of its diversity. The text describes the basic opera-
tion and fabrication of many devices, along with packaging requirements. Inspired
by the adage “a picture is worth a thousand words,” I have included numerous
descriptive schematic illustrations. It is my hope that scanning these illustrations
will aid the reader in quickly developing a basic familiarity with the technology.
Suggestions at the end of each chapter for further reading and an extensive glossary
should supplement the main text.
The following paragraphs present an overview of each chapter in the book.
Chapter 1—MEMS: A Technology from Lilliput. This introductory chapter
defines the scope of the technology and the applications it addresses. A short analy-
sis of existing markets and future opportunities is also included.
Chapter 2—The Sandbox: Materials for MEMS. This chapter reviews the
properties of materials common in micromachining. The emphasis is on silicon
and materials that can be readily deposited as thin films on silicon substrates.
Three physical effects—piezoresistivity, piezoelectricity, and thermoelectricity—are
described in some detail.
Chapter 3—The Toolbox: Processes for Micromachining. Various fabrication
techniques used in semiconductor manufacturing and micromachining are intro-
duced. These include a number of deposition and etch methods, as well as lithogra-
phy. The discussion on etch methods covers the topics of anisotropic etching,
dependence on crystallographic planes, and deep reactive ion etching. Three com-
plete manufacturing process flows are described at the end.

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