Soft X-Rays and Extreme Ultraviolet Radiation: Principles and Applications

503 Pages·1999·17.957 MB·English

by  David Attwood

SOFT X-RAYS AND EXTREME ULTRAVIOLET RADIATION
Thisself-contained,comprehensivebookdescribesthefundamentalpropertiesofsoftx-rays
and extreme ultraviolet (EUV) radiation and discusses their applications in a wide variety
of fields, including EUV lithography for semiconductor chip manufacture and soft x-ray
biomicroscopy.
Theauthorbeginsbypresentingtherelevantbasicprinciplessuchasradiationandscatter-
ing,wavepropagation,diffraction,andcoherence.Hethengoesontoexamineabroadrange
ofphenomenaandapplications.Eachchapterbeginswithasimplesummaryofkeyresultsand
concepts,followedbyanintroductionwithlittleornomathematicssoastobeaccessibleto
thewidestpossibleaudience.Thisisfollowedbyadetailedmathematicaldevelopmentofthe
theoreticalstructureofthesubjectinquestion.ThetopicscoveredincludeEUVlithography,
biomicroscopy, spectromicroscopy, EUV astronomy, synchrotron radiation, and soft x-ray
lasers.
Theauthoralsoprovidesagreatdealofusefulreferencematerialsuchaselectronbinding
energies,characteristicemissionlines,andphotoabsorptioncross-sections.Thebookwillbeof
greatinteresttograduatestudentsandresearchersinengineering,physics,chemistry,andthe
lifesciences.Itwillalsoappealtopracticingengineersinvolvedinsemiconductorfabrication
andmaterialsscience.
David Attwood is the Director of the Center for X-Ray Optics at the Lawrence Berkeley
NationalLaboratory.HeisalsoaProfessorinResidenceinboththeDepartmentofElectrical
EngineeringandComputerScienceandtheGraduateGroupinAppliedScienceandTechnol-
ogyattheUniversityofCalifornia,Berkeley.HeisaFellowoftheOpticalSocietyofAmerica
andhaspublishedover100scientificarticles.

SOFT X-RAYS AND
EXTREME ULTRAVIOLET
RADIATION
PrinciplesandApplications
DAVID ATTWOOD
UNIVERSITYOFCALIFORNIA,BERKELEY
AND
LAWRENCEBERKELEY
NATIONALLABORATORY
CAMBRIDGE UNIVERSITY PRESS
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo
Cambridge University Press
The Edinburgh Building, Cambridge CB2 2RU, UK
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521652148
© Cambridge University Press 1999
This publication is in copyright. Subject to statutory exception
and to the provisions of relevant collective licensing agreements,
no reproduction of any part may take place without
the written permission of Cambridge University Press.
First published 1999
This digitally printed first paperback version (with amendments) 2007
A catalogue record for this publication is available from the British Library
Library of Congress Cataloguing in Publication data
Attwood. David T.
Soft x-rays and extreme ultraviolet radiation : principles and
applications / David Attwood.
p. cm.
Includes bibliographical references.
ISBN 0-521-65214-6 (hbk.)
1. Grenz rays. 2. Ultraviolet radiation. I. Title.
QC482.G68A88 1999
539.7´222 – dc21 99-21078
CIP
ISBN-13 978-0-521-65214-8 hardback
ISBN-10 0-521-65214-6 hardback
ISBN-13 978-0-521-02997-1 paperback
ISBN-10 0-521-02997-X paperback
Cambridge University Press has no responsibility for the persistence or
accuracy of URLs for external or third-party Internet websites referred to
in this publication, and does not guarantee that any content on such websites
is, or will remain, accurate or appropriate.
The colour figures referred to in this publication have been replaced with black and white
images for this digital reprinting. At the time of going to press the original images were
available in colour for download from http://www.cambridge.org/9780521029971
ToProfessorsStanleyGoldstein
andNathanMarcuvitz

Contents
PREFACE pagexiii
ACKNOWLEDGMENTS xv
CHAPTER1. INTRODUCTION 1
1.1 TheSoftX-RayandExtremeUltravioletRegionsoftheElectromagnetic
Spectrum 1
1.2 BasicAbsorptionandEmissionProcesses 5
1.3 AtomicEnergyLevelsandAllowedTransitions 10
1.4 Scattering,Diffraction,andRefractionofElectromagneticRadiation 18
References 21
HomeworkProblems 23
CHAPTER2. RADIATIONANDSCATTERINGATEUVANDSOFT
X-RAYWAVELENGTHS 24
2.1 Maxwell’sEquationsandtheWaveEquation 24
2.2 CalculatingScatteredFields 27
2.3 RadiatedPowerandPoynting’sTheorem 33
2.4 ScatteringCrossSections 38
2.5 ScatteringbyaFreeElectron 39
2.6 ScatteringbyBoundElectrons 41
2.7 ScatteringbyaMulti-electronAtom 44
References 53
HomeworkProblems 54
CHAPTER3. WAVEPROPAGATIONANDREFRACTIVEINDEXATEUVANDSOFT
X-RAYWAVELENGTHS 55
3.1 TheWaveEquationandRefractiveIndex 56
3.2 PhaseVariationandAbsorptionofPropagatingWaves 61
3.3 ReflectionandRefractionatanInterface 66
3.4 TotalExternalReflectionofSoftX-RaysandEUVRadiation 69
vii
viii CONTENTS
3.5 ReflectionCoefficientsatanInterface 71
3.5.1 E PerpendiculartothePlaneofIncidence 71
0
3.5.2 E ParalleltothePlaneofIncidence 77
0
3.6 Brewster’sAngle 80
3.7 FieldPenetrationintoaLossyMediumNeartheCriticalAngle 82
3.8 Determinationofδandβ: TheKramers–KronigRelations 90
3.9 ApplicationstoGlancingIncidenceOptics 94
3.10 EnhancedReflectivityfromPeriodicStructures 95
References 96
HomeworkProblems 97
CHAPTER4. MULTILAYERINTERFERENCECOATINGS 98
4.1 Introduction 98
4.2 ConstructiveInterferenceofScatteredRadiation 99
4.3 ComputationalModelforCalculatingReflectionfromaMultilayerMirror 103
4.4 MultilayerFabrication 106
4.5 ApplicationsofMultilayerCoatedOptics 107
4.5.1 SoftX-RayandExtremeUltravioletPhotoemissionMicroscopy
forSurfaceScience 108
4.5.2 ExtremeUltravioletandSoftX-RayAstronomy 108
4.5.3 ExtremeUltravioletLithography 110
4.5.4 PlasmaDiagnostics 113
4.5.5 PolarizationStudiesofMagneticMaterials 114
4.5.6 TheX-RayMicroprobe 116
References 119
HomeworkProblems 122
CHAPTER5. SYNCHROTRONRADIATION 123
5.1 Introduction 124
5.2 CharacteristicsofBendingMagnetRadiation 126
5.3 CharacteristicsofUndulatorRadiation 135
5.3.1 UndulatorRadiationPattern 137
5.3.2 TheCentralRadiationCone 139
5.4 UndulatorRadiation: CalculationsofRadiatedPower,Brightness,
andHarmonics 141
5.4.1 TheUndulatorEquation 141
5.4.2 CommentsonUndulatorHarmonics 146
5.4.3 PowerRadiatedintheCentralRadiationCone 147
5.4.4 PowerasaFunctionofAngleandTotalRadiatedPower 156
5.4.5 SpectralBandwidthofUndulatorRadiation 161
5.4.6 SpectralBrightnessofUndulatorRadiation 165
5.4.7 TimeStructure 168
5.4.8 PolarizationPropertiesofUndulatorRadiation 170
5.5 TheScaleofHarmonicMotion 172
CONTENTS ix
5.6 TheTransitionfromUndulatortoWigglerRadiation 177
5.7 WigglerPowerandFlux 182
5.8 FemtosecondPulseGeneration 185
References 186
HomeworkProblems 188
CHAPTER6. PHYSICSOFHOTDENSEPLASMAS 189
6.1 Introduction 190
6.2 ShortandLongRangeInteractionsinPlasmas 191
6.3 BasicParametersforDescribingaPlasma 195
6.4 Microscopic,Kinetic,andFluidDescriptionsofaPlasma 197
6.4.1 TheMicroscopicDescription 197
6.4.2 TheKineticDescription 200
6.4.3 TheFluidDescription 202
6.4.4 PlasmaExpansion 211
6.4.5 Electron-AcousticWaves 213
6.4.6 Ion-AcousticWaves 217
6.4.7 TransverseElectromagneticWavesinaPlasma 219
6.4.8 ResonanceAbsorption 227
6.4.9 WavesinaMagnetizedPlasma 227
6.4.10 Non-linearProcessesinaPlasma 227
6.4.11 ThresholdforNon-linearProcesses 232
6.5 NumericalSimulations 234
6.5.1 ParticleinCellSimulations 234
6.5.2 LangrangianZonalCalculationsofPlasmaMassandEnergy
Transport 236
6.6 DensityGradients: UVandEUVProbing 238
6.7 X-RayEmissionfromaHotDensePlasma 241
6.7.1 ContinuumRadiationandBlackbodySpectra 242
6.7.2 LineEmissionandIonizationBottlenecks 246
6.7.3 Sub-kilovoltLineandContinuumEmissions 248
6.7.4 Multi-kilovoltLineEmission 254
6.7.5 SuprathermalX-Rays 256
6.7.6 LaserWavelengthTrends 257
6.8 HighHarmonicGenerationwithFemtosecondLaserPulses 259
References 261
HomeworkProblems 266
CHAPTER7. EXTREMEULTRAVIOLETANDSOFTX-RAYLASERS 267
7.1 BasicProcesses 268
7.2 Gain 274
7.3 RecombinationLasingwithHydrogen-likeCarbonIons 279
7.4 CollisionallyPumpedNeon-likeandNickel-likeLasers 283
7.5 CompactEUVLasers 291
x CONTENTS
References 295
HomeworkProblems 299
CHAPTER8. COHERENCEATSHORTWAVELENGTHS 300
8.1 ConceptsofSpatialandTemporalCoherence 301
8.2 ExamplesofExperimentsthatRequireCoherence 306
8.3 SpatialandSpectralFiltering 309
8.4 SpatialandSpectralFilteringofUndulatorRadiation 310
8.5 SpatiallyCoherentEUVandSoftX-RayLasers 318
8.6 TheVanCittert–ZernikeTheorem 321
8.7 ExamplesofHighContrastFringesFormedatShortWavelengths 330
References 333
HomeworkProblems 336
CHAPTER9. SOFTX-RAYMICROSCOPYWITHDIFFRACTIVEOPTICS 337
9.1 Introduction 338
9.2 TheFresnelZonePlateLens 342
9.3 DiffractionofRadiationbyPinholeAperturesandZonePlates 349
9.3.1 PinholeAperture 351
9.3.2 ZonePlate 353
9.4 SpatialResolutionofaZonePlateLens 357
9.5 DepthofFocusandSpectralBandwidth 361
9.6 SpatialResolutionBeyondtheRayleighLimit: TheEffectiveAngular
IlluminationProfile 363
9.7 HighResolutionSoftX-RayMicroscopy 365
9.7.1 TheSoftX-RayMicroscope 366
9.7.2 TheScanningSoftX-RayMicroscope 367
9.8 ApplicationstotheLifeSciences 369
9.8.1 BiologicalApplicationsoftheSoftX-RayMicroscope 372
9.8.2 BiologicalApplicationsoftheScanningSoftX-RayMicroscope 377
9.9 ApplicationstothePhysicalSciences: AnalyticToolsforMaterialsand
SurfaceScienceatSpatialResolutionsBelow100Nanometers 379
9.10 ZonePlateFabrication 385
References 388
HomeworkProblems 394
CHAPTER10. EXTREMEULTRAVIOLETANDX-RAYLITHOGRAPHY 395
10.1 DeepUltraviolet(DUV)LithographyandBeyond 396
10.2 ExtremeUltraviolet(EUV)Lithography 404
10.3 X-RayProximityLithography 408
References 412
HomeworkProblems 416