Advances in Acoustic Microscopy

374 Pages·1995·10.16 MB·English

by  Gabriel M. Crean, Colm M. Flannery, Séan Cian Ó Mathúna (auth.), Andrew Briggs (eds.)

Advances in
Acoustic Microscopy
Volume 1
Advancesin
Acoustic Microscopy
Volume 1
Editedby
Andrew Briggs
University of Oxford
Oxford, United Kingdom
Springer Science+Business Media, LLC
Llbrary of Congress Cataloglng-ln-Publlcatlon Data
Advances in acoustic microscopy / edited by Andrew Briggs.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-4613-5762-9 ISBN 978-1-4615-1873-0 (eBook)
DOI 10.1007/978-1-4615-1873-0
1. Materials--Microscopy. 2. Acoustic microscopy. r. Briggs.
Andrew.
TA417.23.A38 1994
620.1' 1274--dc20 95-3646
CIP
ISBN 978-1-4613-5762-9
© 1995 Springer Science+Business Media New York
Originally published by Plenum Press in 1995
Softcover reprint of the hardcover 1 st edition
10987654321
AII rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted in
any form or by any means, electronic, mechanical, photocopying, microfilming,
recording, or otherwise, without written permission from the Publisher
For Diana, Felicity, and Lizzie
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Kai t'~v ayti7r1] v, au 7ravOf.1al
cuxaplauJv u7rep Uf.1wv.
Having heard ofy our faith and love,
I never cease to give thanks for you.
Contributors
Jan D. Achenbach, Center for Quality Engineering and Failure Prevention,
Northwestern University, Evanston, Illinois 60208
Abdullah Atalar, Electrical and Electronics Engineering Department, Bilkent
University, Ankara, Turkey
M. Beghi, Dipartimento di Ingegneria Nucieare, Politecnico di Milano, Milano,
Italy and Consorzio Interuniversitario Nazionale per la Fisica della Materia, Unita
di Ricerca Milano Politecnico, Milano, Italy
Jiirgen Bereiter-Hahn, Cinematic Cell Research Group, Zoological Institute,
Johann Wolfgang Goethe University, Frankfurt am Maim, Germany
C. E. Bottani, Dipartimento di Ingegneria Nucieare, Politecnico di Milano,
Milano, Italy and Consorzio Interuniversitario Nazionale per la Fisica della Mate
ria, Unita di Ricerca Milano Politecnico, Milano, Italy
Ayhan Bozkurt, Electrical and Electronics Engineering Department, Bilkent
University, Ankara, Turkey
G. A. D. Briggs, Department of Materials, University of Oxford, Oxford,
England
Gabriel M. Crean, National Microelectronics Research Centre, University
College, Lee Maltings, Cork, Ireland
Colm M. Flannery, National Microelectronics Research Centre, University
College, Lee Maltings, Cork, Ireland
vii
viii
CONTRIBUTORS
G. Ghislotti, Dipartimento di Ingegneria Nucleare, Politecnico di Milano, Mi
lano, Italy
Jin O. Kim, Center for Quality Engineering and Failure Prevention, Northwest
ern University, Evanston, Illinois 60208
Dieter Knauss, Department of Materials, University of Oxford, Oxford,
England
Hayrettin Koymen, Electrical and Electronics Engineering Department, Bil
kent University, Ankara, Turkey
Yung-Chun Lee, Center for Quality Engineering and Failure Prevention,
Northwestern University, Evanston, Illinois 60208
J. W. Martin, Department of Materials, University of Oxford, Oxford, England
Paolo Mutti, Department of Materials, University of Oxford, Oxford, England;
present address: Dipartimento di Ingegneria Nucleare, Politecnico di Milano,
Milano, Italy
Sean Cian 6 Mathuna, Power Electronics Ireland, National Microelectronics
Research Centre, UCC, Ireland
J. R. Sandercock, JRS, Zurich, Switzerland
Zenon Sklar, Department of Materials, University of Oxford, Oxford, England
N. C. Stoodley, Department of Materials, University of Oxford, Oxford,
England
Kazushi Yamanaka, Nanotechnology Division, Medical Engineering Labora
tory, Ministry of International Trade and Industry, Namiki 1-2, Tsukaba, Ibar
aki, Japan
Goksenin Yaralioglu, Electrical and Electronics Engineering Department, Bil
kent University, Ankara, Turkey
T. Zhai, Department of Materials, University of Oxford, Oxford, England
Preface
In 1992 Acoustic Microscopy was published by Oxford University Press, in the
series of Monographs on the Physics and Chemistry of Materials. Reviews
appeared in the Journal of Microscopy [169 (1), 91] and in Contemporary Physics
[33 (4), 296]. At the time of going to press, it seemed that the field of acoustic
microscopy had settled down from the wonderful developments in resolution
that had been seen in the late seventies and the early eighties and from the no
less exciting developments in quantitative elastic measurements that had followed.
One reviewer wrote, "The time is ripe for such a book, now that the expansion
of the subject has perceptively slowed after it was detonated by Lemons and
Quate." [A. Howie, Proc. RMS 27 (4), 280]. In many ways, this remains true. The
basic design for both imaging and quantitative instruments is well-established; the
upper frequency for routine imaging is the 2 GHz established by the Ernst Leitz
scanning acoustic microscope (ELSAM) in 1984. For the most accurate V(z)
measurements, the 225-MHz line-focus-beam lens, developed at Tohoku Univer
sity a little before then, remains standard. The principles of the contrast theory
have been confirmed by abundant experience; in particular the role of surface
acoustic waves, such as Rayleigh waves, dominates the contrast in most high
resolution studies of many materials. But in other ways, it has been delightful
to observe the astonishing advances that have taken place in acoustic microscopy
since the monograph was written. The purpose of this volume is to give an
account of some of the key developments since then.
Perhaps the fastest growing field of applications of acoustic microscopy is
inspection using interior imaging at relatively modest frequencies. There is an
analogy here with what is happening in scanning probe microscopy, where
although many of the most scientifically dramatic pictures come from scanning
tunneling microscopy (STM) imaging with atomic resolution in ultra high vacuum
ix
x
PREFACE
(UHV), nevertheless the greater quantity of industrial applicaton is at a lower
resolution in air with atomic force microscopy. Similarly there is a large volume
of industrial inspection by acoustic microscopy that does not require gigahertz
frequencies and where Rayleigh waves are not excited. Such inspection uses
focused probes and frequencies intermediate between high-resolution acoustic
microscopy and conventional nondestructive testing. Indeed in many ways, it
forms a bridge joining those two kinds of examination. Because of the widespread
importance of this kind of inspection, Chapter I is written by members of
the National Microelectronics Research Centre in Cork, which has extensive
experience of using acoustic microscopy for industrial inspection of electronic
packaging; Chapter I is extensively illustrated with examples of their own work.
It has long been established that acoustic microscopy is a powerful technique
for studying surface cracks. Enhanced contrast arises from the scattering of
Rayleigh waves, which can strike a crack broadside and therefore be strongly
scattered even when the crack opening is much less than the resolution of the
microscope. The contrast theory for this has been worked out in detail and fairly
thoroughly tested. It has also been known for some time that Rayleigh waves
can be diffracted by the tip of a crack and this can be detected in time-resolved
measurements. At much lower nondestructive testing (NDT) frequencies (typi
cally 5 MHz), the depth of crack tips can be measured from the time of flight
of the signal diffracted from the crack tip. There has been strong motivation to
be able to make the same kind of measurement in an acoustic microscope to
study the behavior of cracks at the earliest stages of fatigue. Chapter 2 describes
how this has been achieved at Oxford University using nanosecond time resolution
to measure the subsurface geometry of cracks in metals with a resolution of a
few micro metres.
The use of acoustic microscopy in biology demands perseverance, but re
wards are great because of the possibility of directly imaging and measuring the
elastic properties of cells and tissue. The Cinematic Cell Research Group at
Frankfurt has been active in this field for many years, and Professor Bereiter-Hahn
has produced an authoritative account, richly illustrated from his own experi
ments. Chapter 3 is written from a cytologists point of view, with the particular
hope that life scientists will find it expressed in their own language and addressing
questions relevant to them. There are healthy warnings about constraints of
sample preparation, and problems that remain to be solved to make wider applica
tions possible, but there is also a great deal that has been thoroughly established
and is now available for use in biological applications of acoustic microscopy.
The applications to short cracks and biological cells both involve quantitative
measurements, and the capability for quantitative elastic measurements has be
come increasingly important in acoustic microscopy. The next three chapters are
concerned with measuring various kinds of surface waves. Chapter 4, devoted
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PREFACE
to a critical account of various lens geometries that can be used in acoustic
microscopy, is written by Professor Atalar, one of the original pioneers of acoustic
microscopy with Professor Quate at Stanford University. Professor Atalar pro
duced one of the original formulations of V(z) theory and an early physical
explanation of oscillations in terms of Rayleigh wave excitation. But V(z) mea
surements are not the only way of measuring surface waves if they are dispersive,
and the chapter includes a definitive account of a Lamb wave lens for making
swept-frequency V(f) measurements.
Chapters 5 and 6 give two highly professional accounts of how to analyze
V(z) data from line focus-beam lenses to determine elastic properties of layered
specimens. Chapter 5, which comes from the Center for Quality Engineering and
Failure Prevention at Northwestern University, contains examples from their own
work there on analyzing the elastic properties of coatings. There is a subtle
difference between the methods of inversion in Chapters 5 and 6. In Chapter 5
inversion is performed by calculating V(z) for trial parameters of the sample,
analyzing mode velocities in this calculated curve, and comparing to analyzed
mode velocities in a V(z) curve measured experimentally from the sample. Trial
parameters are then improved by iteration until good agreement is obtained
between mode velocities from calculated and measured V(z) curves. A great
strength of this procedure is that it explicitly focuses on modes that are most
strongly excited in the acoustic microscope and therefore convey most information
about the elastic structure of the sample.
In the method of inversion in Chapter 6, velocities of acoustic modes in the
surface are calculated directly from the trial elastic parameters of the specimen
without calculating a V(z) curve as an intermediate step. In the theoretical model
for doing this, elastic stress is explicitly included, so that it is possible to include
stress among the parameters to be deduced from experimental V(z) data. The
chapter contains a number of examples from the authors' laboratory at Oxford
University. These include elastic constants of hydroxyapatite and ftuoroapatite,
stresses and nonlinear elasticity in silicon, and changes in elastic constants of
amorphous hydrogenated carbon coatings as a function of processing parameters.
In many studies of elastic properties of surfaces, it is desirable to sample a
layer considerably thinner than the 10 micro metres or so (depending on the
Rayleigh velocity) probed in a standard line-focus-beam measurement at 225
MHz. This applies for example to measuring thin coatings and also fine subsurface
damage. To address this, surface Brillouin-scattering spectroscopy has been devel
oped at the Politecnico di Milano to be able to measure surface waves at higher
frequencies. In surface Brillouin spectroscopy, light waves (photons) are scattered
by elastic waves (phonons) in the surface of the sample. Two quantities are
conserved: energy, so that the difference in frequency between the incident and
scattered photons is equal to the frequency of a phonon created or annihilated