Springer Series in

MATERIALS SCIENCE

Springer Series in

MATERIALS SCIENCE

Editors: R. Hull R. M. Osgood, Jr. J. Parisi

The Springer Series in Materials Science covers the complete spectrum of materials physics, including fundamental principles, physical properties, materials theory and design. Recognizing the increasing importance of materials science in future device technologies, the book titles in this series reflect the state-of-the-art in understanding and controlling the structure and properties of all important classes of materials.

61 Fatigue in Ferroelectric Ceramics 70 Applications of the Isotopic Effect and Related Issues in Solids By D.C. Lupascu By V.G. Plekhanov

62 Epitaxy 71 Dissipative Phenomena Physical Principles in Condensed Matter and Technical Implementation Some Applications By M.A. Herman, W. Richter, and H. Sitter By S. Dattagupta and S. Puri

63 Fundamentals 72 Predictive Simulation oflon-lrradiated Polymers of Semiconductor Processing By D. Fink Status and Challenges

64 Morphology Control of Materials Editors: J. Dabrowski and E.R. Weber

and Nanoparticles 73 SiC Power Materials Advanced Materials Processing Devices and Applications and Characterization Editor: Z.C. Feng Editors: Y. Waseda and A. Muramatsu

Plastic Deformation 74 65 Transport Processes in Nanocrystalline Materials

in Ion-Irradiated Polymers By M.Yu. Gutkin and I.A. Ovid'ko By D. Fink

75 Wafer Bonding 66 Multiphased Ceramic Materials Applications and Technology

Processing and Potential Editors: M. Alexe and U. Gosele Editors: W.-H. Than and J.-K. Guo

76 Spirally Anisotropic Composites 67 Nondestructive By G.E. Freger, V.N. Kestelman,

Materials Characterization and D.G. Freger With Applications to Aerospace Materials

77 Impurities Confined Editors: N.G.H. Meyendorf, P.B. Nagy, and S.I. Rokhlin in Quantum Structures

By P.O. Holtz and Q. Zhao 68 Diffraction Analysis

Macromolecular Nanostructured of the Microstructure of Materials 78

Editors: E.J. Mittemeijer and P. Scardi Materials Editors: N. Ueyama and A. Harada

69 Chemical-Mechanical Planarization of Semiconductor Materials Editor: M.R. Oliver

Volumes 10-60 are listed at the end of the book.

D. Fink (Ed.)

Transport Processes in ion-Irradiated Polymers

With 107 Figures and 15 Tables

~Springer

Dr. Dietmar Fink HMI Berlin, Abt. SF4, Glienicker Str. 100 14109 Berlin, Germany

Series Editors:

Professor Robert Hull University of Virginia Dept. of Materials Science and Engineering Thornton HaU Charlottesville, VA 22903-2442, USA

Professor R. M. Osgood, Jr. Microelectronics Science Laboratory Department of Electrical Engineering Columbia University Seeley W. Mudd Building New York, NY 10027, USA

ISSN 0933-033X

Professor Jiirgen Parisi Universitiit Oldenburg, Fachbereich Physik Abt. Energie- und Halbleiterforschung Carl-von-Ossietzky-Strasse 9-11 26129 Oldenburg, Germany

Professor Hans Warlimont Institut fUr Festkorper-und Werkstofforschung, Helmholtzstrasse 20 01069 Dresden, Germany

ISBN 978-3-642-05894-3 ISBN 978-3-662-10608-2 (eBook) DOI 10.1007/978-3-662-10608-2 Library of Congress Control Number: 2004104058

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Preface

The ion irradiation of polymers (which had been treated in Volume 1 of this book) is frequently followed by transport processes, either of the implanted ions themselves or of the activated polymer chains, of radiochemical reaction products inside the irradiated zone, or of foreign atoms, ions or molecules that penetrate into the polymer after the irradiation has taken place (these entities will be called "penetrants" from now on). Transport processes in a polymer can be described in terms of diffusion, permeation, and/or solution phenomena, but there are also cases when, e.g., viscous flow through pores plays a role. There exist many elaborate theories on transport processes in unirradiated polymers, the most important ones of which will be briefly sum­marized in this volume in Chap. 1. Transport processes in irradiated poly­mers are much less well known, but nevertheless the presently available data base already allows one to obtain a rough understanding of the processes occurring. This will be summarized in the subsequent two chapters. As it has turned out that the formation of tracks by energetic heavy ions leads to many peculiarities of the transport processes in polymers, Chap. 3 will be devoted to these cases, while Chap. 2 rather treats the penetrant migration in low­energy ion-irradiated polymers. Finally, Chap. 4 deals with ion-track etching. The latter is of importance as quite a number of technical applications have emerged from the use of etched ion tracks in polymers.

Ion irradiation of polymers has found applications already since about 1950. This concerned especially low-energy ion beams (Chap. 5) that were used in electronics for semiconductor doping through polymeric photoresist masks. In the meantime, the ion-beam modification of polymeric surfaces for medical applications to improve the material's biocompatibility has also found major use, and, furthermore, tribological and optical applications of low-energy ion beams have become more familar.

In order to prepare high-energy irradiated polymers for applications, frequently additional manipulation steps have to be undertaken, e.g. etch­ing, doping with penetrants, deposition of nanoclusters, nanowires, or nano­tubules within the ion tracks, or deposition of additional structures on the polymeric surfaces. Whereas these manipulations will be treated in Chap. 6, the last chapter will be devoted to the emerging applications themselves.

For high-energy ion-beam irradiation of polymers, the major field is found in the production of microporous foils. These etch-track filters have found a

VI Preface

number of well-established applications, and more are currently under dis­cussion or development.

For all applications of ion-irradiated polymers it is of fundamental im­portance to prevent the inherent degradation of their properties due to both the constituent and penetrant motion at ambient temperature, with possibly detrimental oxidative or corrosive reactions. Since this would otherwise re­strict the applicability of polymers to inexpensive throwaway products with limited lifetimes and to low-temperature devices only, the continuous search for new polymer systems with good thermal stability even after their irradi­ation is of central importance.

This volume as well as the preceeding one on the fundamentals of ion­irradiated polymers are thought to challenge the reader to contribute himself to the yet open questions, to deepen our insight and to promote the techno­logical applicability of this fascinating field.

Thanks to everybody who contributed to this book directly or indirectly by numerous discussions at conferences, meetings, etc. Apart from giving spe­cial credit to all the coauthors of this book, I want to acknowledge thankfully the continuous interest and help of Prof. Lewis T. Chadderton, Dr. Man­fred Muller, and Dr. Jiri Vacik over the many years during which the idea of that book emerged, and which helped clarifying many findings that ap­peared to be a riddle in the moment of their discovery. We are also obliged to Dr. Ricarda Klett, Dr. Arne Schmoldt, Prof. Kamal K. Dvivedi, Dr. Svarnali Ghosh, Mr. Prashant Alegaonkar and Mr. Alexander Petrov who obtained quite a number of the results compiled in this book, partly in the frame of their PhD or Postdoc works. Many other important personal communica­tions are mentioned in the references. We thank to Prof. Pedro Grande for his kind help in the chapter on stopping powers and ranges, to Prof. Jochen P. Biersack and to Dr. Amita Chandra for their critical reading, and to Dr. Mahalakshmi Iyer for her technical help in the last chapter of this book. Thanks also to the coauthors for their help in the chapters in which they are not explicitely named. Thanks also to all Publishing Companies who allowed the reproduction of figures in this book.

We are also obliged to the organizations that enabled this work by giving us financial support, especially to the DAAD and CAPES in the frame of the German-Brazil agreement "POBRAL". I also must not forget to mention the continuous support by my home institute, the Hahn-Meitner-Institute Berlin. Last not least I want to thank my good friends all over the world - especially to the families Chadderton, Stange-Ferreira, and Berdinsky, and also to my own family who always supported me with constant encouragement, friend­ship and love, and thus cared for the warm and good atmosphere necessary to write this book.

Berlin, February 2004 Dietmar Fink

Contents

Part I Transport Processes in Polymers

1 Transport Processes: Fundamentals D. Fink and M. Behar........................................... 3 1.1 Diffusion in Polymers: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2 Case I Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.2.1 Regular Fickian Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.2.2 Some Special Cases and Peculiarities. . . . . . . . . . . . . . . . . . . . 11 1.2.3 One-Dimensional Diffusion in a Semi-infinite Medium . . . . . 15 1.2.4 One-Dimensional Diffusion in a Thin Foil. . . . . . . . . . . . . . . . 16 1.2.5 Permeation through a Membrane . . . . . . . . . . . . . . . . . . . . . . . 17 1.2.6 Case I Diffusion with Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 1.2.7 Electrolytes in Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.2.8 Case I Diffusion with Sorption . . . . . . . . . . . . . . . . . . . . . . . . . 21 1.2.9 Chemical Reaction Kinetics. . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1.2.10 Numerical Solution of Diffusive Problems. . . . . . . . . . . . . . . . 26 1.2.11 Clustering Phenomena . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 1.2.12 Three-Dimensional Case I Diffusion. . . . . . . . . . . . . . . . . . . . . 30

1.3 Case II and Anomalous Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 1.3.1 Swelling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 1.3.2 Case II Diffusion Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

1.4 Penetration along Pores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 1.4.1 Diffusional Penetration along Latent Tracks . . . . . . . . . . . . . 34 1.4.2 Penetration along Etched Tracks . . . . . . . . . . . . . . . . . . . . . . . 34 1.4.3 Capillaric Penetration along Tracks . . . . . . . . . . . . . . . . . . . . . 35

1.5 Interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

2 Transport Processes in Low-Energy Ion-Irradiated Polymers D. Fink and V. Hnatowicz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 2.1 Transport of Implanted Penetrants; General Remarks . . . . . . . . . . . 47 2.2 Thermal Diffusion of Implanted Ions . . . . . . . . . . . . . . . . . . . . . . . . . . 51

VIII Contents

2.3 Radiation-Enhanced Diffusion................................ 51 2.3.1 Self-Radiation-Enhanced Transport

of Ions Implanted into Polymers after Low-Fluence Irradiation . . . . . . . . . . . . . . . . . . . . . . . . . . 51

2.3.2 Radiation-Enhanced Transport of Ions in Polymers . . . . . . . 57 2.4 Transport of Metals in Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

2.4.1 Transport of Metals through Metal/Polymer Interfaces.... 60 2.4.2 Transport of Ion-Implanted Metals in Polymers . . . . . . . . . . 61

2.5 Transport Processes of High-Fluence Implanted Ions . . . . . . . . . . . . 63 2.6 Transport Processes of Liquid Penetrants

within Ion-Irradiated Polymers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 2.6.1 Liquid Penetrants in Ion-Irradiated Polymers . . . . . . . . . . . . 67 2.6.2 Transport of Penetrants in Three Dimensions . . . . . . . . . . . . 72

2.7 Penetration of Gases into Ion-Irradiated Polymers . . . . . . . . . . . . . . 75 2.8 The Influence of Surfaces on the Transport of Penetrants . . . . . . . . 78 2.9 Transport of Intrinsic Polymer Components

after Ion Irradiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 2.9.1 Mobility of Radiochemical Products . . . . . . . . . . . . . . . . . . . . 79 2.9.2 Photoresist Inhibitor Mobility. . . . . . . . . . . . . . . . . . . . . . . . . . 80 2.9.3 Thermal-Stability Enhancement of Photoresists . . . . . . . . . . 83

2.10 Transport of Charge Carriers in Irradiated Polymers . . . . . . . . . . . . 85 2.11 Summary and Concluding Remarks........................... 85

3 Transport Processes in Tracks D. Fink, V. Hnatowicz, and P. Yu. Apel............................ 93 3.1 Transport of Solids in Ion Tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

3.1.1 Latent Tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 3.1.2 Etched Tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

3.2 Transport of Liquids in Ion Tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 3.2.1 Penetration of Liquids into Hydrophobic

and Hydrophilic Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 3.2.2 Depth Profiles of Penetrating Liquids . . . . . . . . . . . . . . . . . . . 96 3.2.3 Transport of Liquids into Latent Tracks:

Corrosion Effects and Aging ........................... 116 3.2.4 Swelling after Penetration of Liquids into Latent Tracks ... 117 3.2.5 Latent-Track Sensibilization (Sensitization)

and Grafting ......................................... 119 3.2.6 Transport of Liquids through Etched Tracks ............. 120 3.2. 7 Transport of Suspended Particles

through Etched Tracks ................................ 122 3.2.8 Transport Processes in Irradiated Biological Matter ....... 123

3.3 Transport of Gases in Ion Tracks ............................. 124 3.3.1 Latent Tracks ........................................ 124 3.3.2 Etched Tracks ....................................... 127

Contents IX

3.4 Current Transport through Ion Tracks Embedded in Liquids . . . . . 128 3.4.1 Electrolytes in Latent Tracks .......................... 128 3.4.2 Etched Tracks ....................................... 130

3.5 Transmission of Energetic Ions through Tracks in Vacuum ....... 135 3.5.1 Latent Tracks ........................................ 135 3.5.2 Etched Tracks ....................................... 135

4 Ion-Track Etching P. Yu. Apel and D. Fink .......................................... 147 4.1 Basics of Etching Physics and Chemistry ...................... 147

4.1.1 Etching Kinetics ..................................... 147 4.1.2 Etching of Hydrophobic and Hydrophilic Polymers ....... 149 4.1.3 Ion-Track Swelling .................................... 152 4.1.4 Etching of Polymers with Structural Inhomogeneities.

Why Are Ion Tracks Preferentially Etched? .............. 155 4.1.5 Selection of Appropriate Etchants

for Developing Ion Tracks ............................. 157 4.2 Etching Threshold and Track-Etch Sensitivity .................. 163

4.2.1 Basic Definitions ..................................... 163 4.2.2 Sensitivity Depends on the Polymer Structure ........... 165 4.2.3 Sensitivity Depends on the Etching Conditions ........... 166 4.2.4 Track-Etch Response at High Stopping Power ............ 168 4.2.5 The Realization of Ion-Track Etching ................... 170

4.3 Environmental Effects and Track Sensitization ................. 172 4.4 Shapes of Etched Tracks .................................... 176

4.4.1 Modeling the Track Shape on the Microscopic Scale ...... 176 4.4.2 Examples of Etched Tracks in Polymers ................. 179 4.4.3 Track Etching in the Case of Insoluble Fillers

or Etching Products .................................. 182 4.5 Etched-Track Profiles in the Nanometer Range ................. 186 4.6 Thermal Stability of Etched Tracks ........................... 192 4. 7 Techniques to Improve the Visibility

of Very Small Etched Tracks ................................. 192 4.8 Cases of Inverse Etching ..................................... 193

Part II Applications

5 Applications of Low-Energy Polymer Ion Irradiation V. Hnatowicz and D. Fink ....................................... 205 5.1 Lithography for Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 5.2 Micromachining by Focused Ion Beams ........................ 208 5.3 Applications of Ion-Beam-Modified Surfaces ................... 209

5.3.1 Tribological Applications .............................. 209 5.3.2 Enhancement of Metal-Polymer Adhesion ............... 210

X Contents

5.3.3 Aerospace Technology: Applications that Require Enhanced Chemical Resistance ......................... 210

5.3.4 Nuclear-Waste Management: Applications that Require Reduced Permeability ......... 211

5.4 Applications of Changes of Optical Properties of Irradiated Polymers ...................................... 211

5.5 Applications of Changes of Electrical Conductivity of Irradiated Polymers ...................................... 212

5.6 Ion-Beam-Modified Polymers for Medicine and Biotechnology .... 215

6 Ion-Track Manipulations D. Fink ........................................................ 227 6.1 Manipulation of Latent Tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

6.1.1 Material Chemical Conversion and Phase Transitions ..... 227 6.1.2 Trapping of Migrating Impurities at Latent Tracks ....... 228 6.1.3 Use of Ion-Induced Excess Free Volume ................. 228 6.1.4 Manipulation of Latent Tracks

for Production of Etched-Track Patterns . . . . . . . . . . . . . . . . 228 6.2 Manipulation of Etched Tracks ............................... 229

6.2.1 Formation of Track Templates from the Vapor Phase ..... 229 6.2.2 Formation of Massive Track Templates

(Rods, Wires, Fibers) from the Liquid Phase. . . . . . . . . . . . . 232 6.2.3 Tubule Formation by Chemical Bath

and Electrodeless Deposition Processes . . . . . . . . . . . . . . . . . . 242 6.3 Formation of Complex Nanostructures ........................ 252 6.4 Electrical and Magnetic Properties of Nanowires

and Nanotubules ........................................... 256 6.5 Nonstatistical Ion-Track Distributions ......................... 259 6.6 Approaches Competing with Ion Tracks for Applications ........ 260

7 Ion-Track Applications D. Fink, P. Yu. Apel, and R.H. Iyer ............................... 269 7.1 Applications of Latent Tracks ................................ 269 7.2 Applications of Etched Tracks ................................ 271

7.2.1 Etched-Track Membranes ............................. 271 7.2.2 Applications of Ion Tracks

in Dosimetry and Related Fields . . . . . . . . . . . . . . . . . . . . . . . 27 4 7.2.3 Applications of Etched Tracks in Lithography ............ 274 7.2.4 Applications of Etch Tracks for Galvanic Replicas ........ 275 7.2.5 Applications of Etched Tracks in Separation Technology ... 275 7.2.6 Applications of Etched Tracks in Sensing Technology ..... 280 7.2. 7 Other Chemical Applications of Etched Tracks ........... 285 7.2.8 Biomedical Applications ............................... 285 7.2.9 Applications of Etched Tracks

in Novel Packing Materials ............................ 288

Contents XI

7.2.10 Electronic Applications ............................... 292 7.2.11 Magnetic Applications ................................ 300 7.2.12 Optical Applications .................................. 304 7.2.13 Mechanical Applications? ............................. 306 7.2.14 Statistical or Spatially Defined Ion Impact? .............. 306

Part III Conclusion

8 Concluding Remarks D. Fink ........................................................ 317

Index ......................................................... 325

List of Contributors

Pawel Yu. Apel Joint Institute of Nuclear Research Dubna Flerov Lab. of Nuclear Reactions 141980 Dubna, Russia apel~cv.jinr.dubna.ru

Moni Behar lnstituto de Fisica Universidade Federal do Rio Grande do Sul Av. Bento Gon<_<alves 9500, C.P.15051 91501-970 Porto Alegre, R.S., Brazil behar~if.ufrgs.br

Dietmar Fink Abt. SF4 Hahn-Meitner-lnstitut Berlin Glienicker Str. 100 D-14109 Berlin, Germany fink~hmi.de

Vladimir Hnatowicz Nuclear Physics Institute 25068 Rez, Czech Republic hnatowicz~ujf.cas.cz

R.H. lyer Nuclear Recycle Group Bhabha Atomic Research Centre Trombay, Mumbai 400 085, India rhiyer@magnum.barc.ernet.in

Ricardo M. Papaleo lnstituto de Fisica Pontificada Universidade Catolica do Rio Grande do Sul Av. lpiranga 6681, C.P.1429 91619-900 Porto Alegre, R.S., Brazil papaleo~if.ufrgs.br