Introduction to Microlithography. Theory, Materials, and Processing

364 Pages·1983·6.16 MB·English

by  L. F. Thompson, C. G. Willson, and M. J. Bowden (Eds.)

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Introduction
to Microlithography
Theory, Materials, and Processing
L. F. Thompson, EDITOR
Bell Laboratories
C. G. Willson, EDITOR
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2 M. J. Bowden, EDITOR
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Dat and Plastics Chemistry
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American Chemical Society,
Seattle, Washington,
March 20-25, 1983

219
ACS SYMPOSIUM SERIES
AMERICAN CHEMICAL SOCIETY
WASHINGTON, D. C. 1983
Library of Congress Cataloging in Publication Data
Introduction to microlithography.
(ACS symposium series, ISSN 0097-6156; 219)
Includes bibliographies and index.
Contents: An introduction to lithography/L. F.
01 Thompson—The lithographic process—the physics/
w0 L. F. Thompson and M. J. Bowden—Organic resist
9.f materials—theory and chemistry/C. Grant Willson—
1 [etc.]
2
0
3- 1. Photolithography—Congresses. 2. Photoresists—
98 Congresses.
bk-1 C.I .G Trahnotm, p1s9o3n9,- L arry. FII.I,. 1B94o4w-d en, .M IuIr.r aWe ilJls.o nS.,,
1/ 1943- . IV. American Chemical Society. Division
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10 of Organic Coatings and Plastics Chemistry. V. Amer
0. ican Chemical Society. National Meeting (185th:
1
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3 | d TISRB9N40 0.I5-874 12-0717958-35 686.2'315 83-5968
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cati Copyright © 1983
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ACS Symposium Series
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Marvin Margoshes Charles S. Tuesday
Donald E. Moreland C. Grant Willson
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19.f FOREWORD
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1 IN CHEMISTRY SERBES except that in order to save time the
oi: papers are not typeset but are reproduced as they are sub
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1 viewed under the supervision of the Editors with the assistance
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PREFACE
THE REMARKABLE PROGRESS in the miniaturization of electronic devices
over the past three decades promises to continue for many years. At the
heart of this revolution is the silicon integrated circuit (IC) whose com­
plexity and performance continue to increase, paving the way for continued
innovation in solid state devices. The improvements in IC performance
stem primarily from an ability to internally interconnect more and more
active components (transistors, diodes, etc.) on a single "chip" of silicon.
In 1965, 250 devices could be interconnected in the "monolithic integrated
circuit" and in 1983 over 1,000,000 devices are routinely connected in a
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0 single device. This improvement has come about largely through a decrease
pr
9. in the size of the circuit elements. The size (area) of the chips has not
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8 decreased from >20 μχη in 1963 to <2.0 ^m in 1983.
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21/ processes collectively known as "lithography". The pattern is first generated
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0.1 in a polymeric film on a device "wafer" and this pattern is then transferred
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3 | d review the theory, materials, and processes that are used in the lithographic
8 process. This book is intended to be a tutorial and not a comprehensive
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3, review. Each chapter contains many references to which the reader can
ay refer for more detail on any specific aspect of microlithography.
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e: The authors are indebted to the Bell Laboratories Text Processing group,
Dat especially T. I. Howard, J. Alder, and M. McCann. Special thanks also
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Pu L. F. THOMPSON

Bell Telephone Laboratories
Murray Hill, NJ 07974
C. G. WILLSON
IBM Research Laboratories
San Jose, CA 95193
M. J. BOWDEN
Bell Telephone Laboratories
Murray Hill, NJ 07974
February 18, 1983
ix
1
An Introduction to Lithography
L. F. THOMPSON
Bell Laboratories, Murray Hill, NJ 07974
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3-0 1.1 Historical Perspective 2
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9 1.1.a Solid State Devices 3
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k- 1.1.b Lithography, the Art 7
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1 1.2.a Photolithography 9
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1 1.2.b X-ray Lithography 9
doi: 1.2.c Electron Beam Lithography 10
3 | 1.3 Resist Materials and Processes 10
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0097-6156/83/0219-0001$06.00/0
© 1983 American Chemical Society
2 INTRODUCTION TO MICROLITHOGRAPHY
1.1 Historical Perspective
Soon after the invention of the point contact transistor over three decades
ago, several important technological trends were rapidly established. First,
a technology known as planar junction technology (1) was developed; the
development of this technology permitted the construction of p-n junctions
in a semiconductor material without the use of bulky, three-dimensional
contact devices. Within a few years, silicon had become the dominant
material for semiconductor fabrication, and photolithography was esta
blished as the technique of choice in fabricating planar, silicon devices.
Numerous volumes have been written about the chemistry and physics of
semiconductor devices and of materials for semiconductor manufacturing
(2-4). Much less information has been compiled concerning the processing
01 steps involved in semiconductor device fabrication, especially in the area of
0
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1 Another important innovation in semiconductor devices was the
2
3-0 invention of the monolithic integrated circuit. This technology provides a
98 means for the internal interconnection of many solid-state and passive dev
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k- ices into a working unit that performs complex, electronic functions and
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2
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1 times over that achievable with discrete or single transistor devices. The
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1 past two decades have seen an astronomical growth in the microelectronics
oi: industry and associated technologies. The application of microelectronics
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19 energy, and more recently, home entertainment. This revolution is going to
3, continue for the foreseeable future and will require continued advances in
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Dat manufacturing technologies.
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cati ices smaller, this results in more active-circuits per unit area (5). Figure 1
ubli illustrates this trend, and it is the conviction of the author that this will con
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tinue for at least two more decades. It is interesting to note that not only
are we decreasing the size of the elements in an integrated circuit while
increasing the number of active devices, but that the average cost per chip is
also remaining essentially constant — that is the cost per function is decreas
ing dramatically. This trend has required and will continue to require a
greater understanding of device physics, device design, and lithography.
Microcircuit fabrication requires the selective diffusion of tiny amounts of
impurities into specific regions of the semiconductor substrate to produce the
desired electrical characteristics of the circuit. These regions are defined by
lithographic processes in which the desired pattern is first defined in a resist
layer (usually a polymeric film which is spin-coated onto the substrate) and
1. THOMPSON Introduction to Lithography 3
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subsequently transferred, via techniques such as etching, ion implantation
and/or diffusion, to the underlying substrate. This process is shown
schematically in Figure 2. The purposes of this book are: (a) to review the
lithographic strategies currently being used and under development, and (b)
to emphasize in particular, the importance of resists and resist processing in
achieving each individual lithographic technology goal.
1.1.a Solid State Devices. Many designs and strategies for device design
and fabrication have intervened between the point contact transistor and the
planar technology to which we alluded earlier, including grown junction
transistors, alloyed junction transistors, and many variations of the planar
technology. An understanding of the definition of integrated circuits,
together with the details of the physics involved in their operation, is an