Glancing Angle Deposition of Thin Films: Engineering the Nanoscale

316 Pages·2014·7.25 MB·English

by  Matthew M. Hawkeye

Wiley Series in Materials for
Electronic & Optoelectronic Applications
Matthew M. Hawkeye
Michael T. Taschuk
Michael J. Brett
Glancing Angle
Deposition of
Thin Films
Engineering the Nanoscale

Glancing Angle Deposition
of Thin Films
WileySeriesinMaterials forElectronicandOptoelectronic
Applications
www.wiley.com/go/meoa
SeriesEditors
ProfessorArthurWilloughby,UniversityofSouthampton,Southampton,UK
DrPeterCapper,SELEXGalileoInfraredLtd,Southampton,UK
ProfessorSafaKasap,UniversityofSaskatchewan,Saskatoon,Canada
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andK.Maex
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P.CapperandM.Mauk
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M.Skorobogatiy
PhotovoltaicMaterials:FromCrystallineSilicontoThird-GenerationApproaches,
EditedbyG.ConibeerandA.Willoughby
Glancing Angle Deposition
of Thin Films
Engineering the Nanoscale
Matthew M. Hawkeye
DepartmentofElectricalandComputerEngineering
UniversityofAlberta
Canada
Michael T. Taschuk
DepartmentofElectricalandComputerEngineering
UniversityofAlberta
Canada
Michael J. Brett
DepartmentofElectricalandComputerEngineering
UniversityofAlberta
Canada
NRCNationalInstituteforNanotechnology
Canada
Thiseditionfirstpublished2014
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LibraryofCongressCataloging-in-PublicationData
Hawkeye,MatthewM.
Glancingangledepositionofthinfilms:engineeringthenanoscale/MatthewM.Hawkeye,MichaelT.
Taschuk,MichaelJ.Brett,NRCNationalInstituteforNanotechnology.
pagescm
Includesbibliographicalreferencesandindex.
ISBN978-1-118-84756-5(cloth)
1.Nanotechnology. 2.Chemicalvapordeposition. 3.Nanoelectromechanicalsystems–Designand
construction. I.Taschuk,MichaelT. II.Brett,MichaelJ. III.Title.
T174.7.H392014
621.3815′2–dc23
2014013307
AcataloguerecordforthisbookisavailablefromtheBritishLibrary.
ISBN:9781118847565
Setin10/12ptTimesbyAptaraInc.,NewDelhi,India
1 2014
Contents
SeriesPreface xi
Preface xiii
1 Introduction:GlancingAngleDepositionTechnology 1
1.1 Nanoscaleengineeringandglancingangledeposition 1
1.2 GLAD-vantages 4
1.2.1 Nanoscalemorphologycontrol 4
1.2.2 Broadmaterialcompatibility 6
1.2.3 Novelthin-filmmaterialproperties 10
1.2.4 Compatibilitywithstandardmicrofabricationprocesses 10
1.2.5 Scalablefabricationmethod 11
1.3 Therootsofglancingangledeposition:obliquedeposition 12
1.4 Theimportanceofexperimentalcalibration 13
1.5 Computersimulationsofglancingangledepositiongrowth 15
1.6 Majorapplicationareasinglancingangledepositiontechnology 17
1.6.1 Energyandcatalysis 17
1.6.2 Sensingapplications 19
1.6.3 Optics 20
1.7 Summaryandoutlineofthebook 21
References 22
2 EngineeringFilmMicrostructurewithGlancingAngleDeposition 31
2.1 Introduction 31
2.2 Basicsofconventionalfilmgrowth 32
2.2.1 Physicalvapourdeposition 32
2.2.2 Nucleationandcoalescence 33
2.2.3 Columnmicrostructure 35
2.3 Glancingangledepositiontechnology:microstructuralcontrolvia
substratemotion 37
2.4 Engineeringfilmmorphologywith𝛼 41
2.4.1 Controllingmicrostructureandporosity 41
2.4.2 Directionalcolumngrowth:columntilt𝛽 44
2.5 Engineeringfilmmorphology:columnsteeringvia𝜑rotation 47
2.5.1 Controllingcolumnarchitecturewith𝜑:helicalcolumns 47
2.5.2 Controllingmicrostructurewithrotationspeed:verticalcolumns 48
2.5.3 Continuousversusdiscretesubstraterotation 49
vi CONTENTS
2.6 Growthcharacteristicsofglancingangledepositiontechnologyfilms 53
2.6.1 Evolutionarycolumngrowth 53
2.6.2 Columnbroadening 56
2.6.3 Columnbifurcation 57
2.6.4 Anisotropicshadowingandcolumnfanning 59
2.7 Advancedcolumnsteeringalgorithms 60
2.7.1 𝛽 variationsinzigzagmicrostructures 61
2.7.2 Spin–pause/two-phasesubstraterotation:decoupling𝛽 andfilm
density 63
2.7.3 Phisweepmotion:competition-resilientstructuregrowth 67
2.8 Additionalcontroloverfilmgrowthandstructure 72
2.8.1 High-temperatureglancingangledepositiongrowth 72
2.8.2 Multimaterialstructures:co-depositionprocesses 75
References 77
3 CreatingHigh-UniformityNanostructureArrays 81
3.1 Introduction 81
3.2 Seedlayerdesign 82
3.2.1 Seedspacingandseedheight 84
3.2.2 Seedlatticegeometry 86
3.2.3 Seedsize 87
3.2.4 Planarfillfraction 89
3.2.5 Seedshape 90
3.2.6 Two-dimensionalshadowcoverage 91
3.2.7 Seedmaterial 94
3.2.8 Designparametersummary 95
3.3 Seedfabrication 95
3.3.1 Conventionaltechniques 96
3.3.2 Unconventionaltechniques 97
3.4 Advancedcontroloflocalshadowingenvironment 99
3.4.1 Preventingbifurcation:slow-cornermotion 99
3.4.2 Preventingbroadening:phisweepandsubstrateswing 102
References 108
4 PropertiesandCharacterizationMethods 113
4.1 Introduction 113
4.2 Structuralanalysiswithelectronmicroscopy 113
4.2.1 Practicalaspects 114
4.2.2 Scanningelectronmicroscopeimageanalysis 117
4.2.3 Three-dimensionalcolumnimaging:tomographicsectioning 122
4.2.4 Characterizinginternalcolumnstructurewithtransmissionelectron
microscopeimaging 124
4.3 Structuralpropertiesofglancingangledepositionfilms 126
4.3.1 Filmsurfaceroughnessandevolution 126
4.3.2 Columnbroadening 128
4.3.3 Intercolumnspacingandcolumndensity 133
CONTENTS vii
4.4 Filmdensity 134
4.4.1 Controllingdensitywith𝛼:theoreticalmodels 135
4.4.2 Experimentalmeasurementandcontroloffilmdensity 136
4.5 Porosimetryandsurfaceareadetermination 140
4.5.1 Surfaceareaenhancementinglancingangledepositionfilms 141
4.5.2 Theporestructureofglancingangledepositionfilms 144
4.6 Crystallographictextureandevolution 146
4.7 Electricalproperties 148
4.7.1 Resistivityinmicrostructuredglancingangledepositionfilms 148
4.7.2 Anisotropicresistivity 151
4.7.3 Modellingglancingangledepositionfilmresistivity 153
4.7.4 Individualnanocolumnproperties 154
4.8 Mechanicalproperties 155
4.8.1 𝛼effectsonfilmstress 155
4.8.2 Hardnessproperties 158
4.8.3 Elasticbehaviourofglancingangledepositionfilms 159
4.8.4 Additionalmechanicalproperties 163
References 164
5 GlancingAngleDepositionOpticalFilms 173
5.1 Introduction 173
5.2 Theopticsofstructuredglancingangledepositionfilms 173
5.2.1 Opticalanisotropyincolumnarglancingangledepositionfilms 173
5.2.2 Modellingglancingangledepositionfilmswitheffectivemedium
theory 176
5.2.3 Thecolumnandvoidmaterialrefractiveindices 179
5.2.4 Modellingformbirefringenceviathedepolarizationfactor 180
5.2.5 Dealingwithmicrostructuraluncertainty:boundsontheeffective
dielectricfunction 182
5.3 Calibratingopticalpropertiesofglancingangledepositionfilms 182
5.3.1 Basicmeasurements:isotropicapproximations 183
5.3.2 Calibratinganisotropywithpolarization-sensitivemeasurements 185
5.3.3 In-depthcharacterizationwithgeneralizedtechniques 186
5.3.4 Additionalfactors 186
5.4 Controllingglancingangledepositionfilmopticalproperties 187
5.4.1 Basicrefractiveindexengineeringwith𝛼 187
5.4.2 Controllingplanarbirefringencewith𝛼 188
5.4.3 Optimizingbirefringencewithserialbideposition 189
5.4.4 Modulatingbirefringencewithcomplex𝜑motions 192
5.4.5 Controllingnwithadvancedglancingangledepositionmotions 195
5.5 Graded-indexcoatings:designandfabrication 195
5.5.1 Generaldesignmethodforglancingangledepositiongraded-index
coatings 196
5.5.2 Designing𝜑motionsforhigh-accuracygraded-indexcoatings 197
5.5.3 Specificexamples 199
5.5.4 Antireflectioncoatings 199
viii CONTENTS
5.5.5 Rugateinterferencefilters 201
5.5.6 Avoidinghigh-𝛼growthinstabilitiesingraded-indexfilms 205
5.6 Designinghelicalstructuresforcircularpolarizationoptics 206
5.6.1 Opticsofchiralglancingangledepositionmedia 206
5.6.2 Engineeringbasichelicalstructures 208
5.6.3 Polygonalhelicalstructures 210
5.6.4 Optimizationofcircularbraggphenomenawithserialbideposition 212
5.6.5 Microcavitydesigninhelicalstructures 213
5.6.6 Fabricatinggraded-birefringencethin-filmdesigns 214
5.7 Practicalinformationandissues 216
5.7.1 Post-depositiontuning 216
5.7.2 Environmentalsensitivity 217
5.7.3 Opticalscattering 217
References 218
6 Post-DepositionProcessingandDeviceIntegration 227
6.1 Introduction 227
6.2 Post-depositionstructuralcontrol 227
6.2.1 Annealing 227
6.2.2 Chemicalcompositioncontrol 231
6.2.3 Microstructuralcontrolviachemicaletching 231
6.2.4 Ion-millingstructuralmodification 233
6.2.5 Columnsurfacemodifications 235
6.3 Depositionontononplanargeometries 236
6.4 Photolithographicpatterningofglancingangledepositionthinfilms 237
6.5 Encapsulationandreplanarizationofglancingangledepositionfilms 240
6.5.1 Encapsulationlayersubstratemotions 240
6.5.2 Filmstressinencapsulationlayers 242
6.6 Integratingelectricalcontactswithglancingangledeposition
microstructures 244
6.6.1 Planarelectrodeconfigurations 244
6.6.2 Parallel-plateelectrodeconfigurations 245
6.7 Filmsinliquidenvironments 247
6.8 Usingglancingangledepositionmicrostructuresasreplicationtemplates 251
6.8.1 Single-anddouble-templatefabricationprocesses 251
6.8.2 Nanotubefabricationviatemplatefabrication 252
References 254
7 GlancingAngleDepositionSystemsandHardware 261
7.1 Introduction 261
7.2 Vacuumconditions 261
7.2.1 Vacuumrequirementsforglancingangledepositionsystems 261
7.2.2 Physicalvapourdepositionprocessgasesandhigherpressure
deposition 263
7.3 Thicknesscalibrationanddepositionratemonitoring 265
7.3.1 Sourcedirectionalityandtoolingfactor 265
7.3.2 Thicknesscalibrationatnonzero𝛼:depositionratios 267
7.3.3 Extendedsource:effectoncollimation 269