The Materials Science of Thin Films

Samer Elatrache V-17810600 estudiante de CRF
Thin-film science and technology play a crucial role in the high-tech industries
that will bear the main burden of future American competitiveness. While the
major exploitation of thin films has been in microelectronics, there are
numerous and growing applications in communications, optical electronics,
coatings of all kinds, and in energy generation and conservation strategies. A
great many sophisticated analytical instruments and techniques, largely developed
to characterize thin films and surfaces, have already become indispensable
in virtually every scientific endeavor irrespective of discipline. When I
was called upon to offer a course on thin films, it became a genuine source of
concern to me that there were no suitable textbooks available on this unquestionably
important topic. This book, written with a materials science flavor, is
a response to this need. It is intended for
1.
2.
3.
Science and engineering students in advanced undergraduate or first-year
graduate level courses on thin films
Participants in industrial in-house courses or short courses offered by
professional societies
Mature scientists and engineers switching career directions who require an
overview of the field.
Readers should be reasonably conversant with introductory college chemistry
and physics and possess a passive cultural familiarity with topics commonly
treated in undergraduate physical chemistry and modem physics courses.
It is worthwhile to briefly elaborate on this book's title and the connection
between thin films and the broader discipline of materials science and engineering.
A dramatic increase in our understanding of the fundamental nature of
materials throughout much of the twentieth century has led to the development
of materials science and engineering. This period witnessed the emergence of
polymeric, nuclear, and electronic materials, new roles for metals and ceramics,
and the development of reliable methods to process these materials in bulk
and thin-film form. Traditional educational approaches to the study of materials
have stressed structure-property relationships in bulk solids, typically
utilizing metals, semiconductors, ceramics; and polymers, taken singly or
collectively as illustrative vehicles to convey principles. The same spirit is
adopted in this book except that thin solid films are the vehicle. In addition,
the basic theme has been expanded to include the multifaceted processingstructure-
properties-performance interactions. Thus the original science
core is preserved but enveloped by the engineering concerns of processing
and performance. Within this context, I have attempted to weave threads of
commonality among seemingly different materials and properties, as well as to
draw distinctions between materials that exhibit outwardly similiar behavior. In
particular, parallels and contrasts between films and bulk materials are recurring
themes.
An optional introductory review chapter on standard topics in materials
establishes a foundation for subsequent chapters. Following a second chapter
on vacuum science and technology, the remaining text is broadly organized
into three categories. Chapters 3 and 4 deal with the principles and practices of
film deposition from the vapor phase. Chapters 5-9 deal with the processes
and phenomena that influence the structural, chemical, and physical attributes
of films, and how to characterize them. Topics discussed include nucleation,
growth, crystal perfection, epitaxy, mass transport effects, and the role of
stress. These are the common thin-film concerns irrespective of application.
The final portion of the book (Chapters 10-14) is largely devoted to specific
film properties (electrical, magnetic, optical, mechanical) and applications, as
well as to emerging materials and processes. Although the first nine chapters
may be viewed as core subject matter, the last five chapters offer elective
topics intended to address individual interests. It is my hope that instructors
using this book will find this division of topics a useful one.
Much of the book reflects what is of current interest to the thin-film research
and development communities. Examples include chapters on chemical vapor
deposition, epitaxy, interdiffusion and reactions, metallurgical and protective
coatings, and surface modification. The field is evolving so rapidly that even
the classics of yesteryear, e.g., Maissel and Glang, Handbook of Thin Film
Technology (1970) and Chopra, Thin Film Phenomena (1969), as well as
more recent books on thin films, e.g., Pulker, Coatings on Glass (1984), and
Eckertova, Physics of Thin Films (1986), make little or no mention of these
now important subjects.
As every book must necessarily establish its boundaries, I would like to
point out the following: (1) Except for coatings (Chapter 12) where thicknesses
range from several to as much as hundreds of microns (1 micron or 1
pm = lop6 meter), the book is primarily concerned with films that are less
than 1 pm thick. (2) Only films and coatings formed from the gas phase by
physical (PVD) or chemical vapor deposition (CVD) processes are considered.
Therefore spin and dip coating, flame and plasma spraying of powders,
electrolytic deposition, etc., will not be treated. (3) The topic of polymer films
could easily justify a monograph of its own, and hence will not be discussed
here. (4) Time and space simply do not allow for development of all topics
from first principles. (Nevertheless, I have avoided using the unwelcome
phrase "It can be shown that . . . ," and have refrained from using other
textbooks or the research literature to fill in missing steps of derivations.) (5) A
single set of units (e.g., CGS, MKS, SI, etc.) has been purposely avoided to
better address the needs of a multifaceted and interdisciplinary audience.
Common usage, commercial terminology, the research literature and simple
bias and convenience have all played a role in the ecumenical display of units.
Where necessary, conversions between different systems of units are provided.
At the end of each chapter are problems of varying difficulty, and I believe a
deeper sense of the subject matter will be gained by considering them. Three
very elegant problems (Le. 9-6, -7, -8) were developed by Professor W. D.
Nix, and I thank him for their use.
By emphasizing immutable concepts, I hope this book will be spared the
specter of rapid obsolescence. However, if this book will in some small
measure help spawn new technology rendering it obsolete, it will have served a
useful function