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Magnetic Field Assisted Finishing of Ultra-Lightweight and High-Resolution MEMS X-Ray Micro-Pore Optics

Permanent Link: http://ufdc.ufl.edu/UFE0024588/00001

Material Information

Title: Magnetic Field Assisted Finishing of Ultra-Lightweight and High-Resolution MEMS X-Ray Micro-Pore Optics
Physical Description: 1 online resource (78 p.)
Language: english
Creator: Riveros, Raul
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: drie, finishing, liga, magnetic, micropore, polishing, x
Mechanical and Aerospace Engineering -- Dissertations, Academic -- UF
Genre: Mechanical Engineering thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: In recent years, x-ray telescopes have been shrinking in both size and weight to reduce cost and volume on space flight missions. Current designs focus on the use of micro-electro-mechanical systems (MEMS) technologies to fabricate ultra-lightweight and high-resolution Wolter type I x-ray optics. In 2006, Ezoe et al. introduced micro-pore x-ray optics fabricated using anisotropic wet etching of silicon (110) wafers. These optics, though lightweight (complete telescope weight less than 1 kg for an effective area of 1000 cm^2, had limited angular resolution, as the reflecting surfaces were flat crystal planes. To achieve higher angular resolution, curved micro-pores are required. Two MEMS techniques were used to fabricate x-ray optics with curvilinear micro-pores; however, the resulting curved sidewalls were too rough to reflect x-rays. To solve this issue, an ultra-precision polishing process employing alternating magnetic field assisted finishing was proposed. A processing principle was devised using a magnetic abrasive fluid mixture and an alternating and switching magnetic field. The concept involves two coaxial, inward facing, magnetic poles. The micro-pore optic is submerged in the fluid mixture and placed between the poles. The fluid mixture oscillates from pole to pole, flowing through the optic's micro-pores, thus polishing the sidewalls. A machine was constructed to realize this principle on miniature work pieces called mirror chips (7.5 mm^2 wafers with micro-pores). The effects on sidewall roughness of several process parameters were studied, and improvements in micro-pore sidewall roughness were seen. The x-ray reflectance of the polished mirror chips was also confirmed.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Raul Riveros.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Greenslet, Hitomi.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024588:00001

Permanent Link: http://ufdc.ufl.edu/UFE0024588/00001

Material Information

Title: Magnetic Field Assisted Finishing of Ultra-Lightweight and High-Resolution MEMS X-Ray Micro-Pore Optics
Physical Description: 1 online resource (78 p.)
Language: english
Creator: Riveros, Raul
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: drie, finishing, liga, magnetic, micropore, polishing, x
Mechanical and Aerospace Engineering -- Dissertations, Academic -- UF
Genre: Mechanical Engineering thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: In recent years, x-ray telescopes have been shrinking in both size and weight to reduce cost and volume on space flight missions. Current designs focus on the use of micro-electro-mechanical systems (MEMS) technologies to fabricate ultra-lightweight and high-resolution Wolter type I x-ray optics. In 2006, Ezoe et al. introduced micro-pore x-ray optics fabricated using anisotropic wet etching of silicon (110) wafers. These optics, though lightweight (complete telescope weight less than 1 kg for an effective area of 1000 cm^2, had limited angular resolution, as the reflecting surfaces were flat crystal planes. To achieve higher angular resolution, curved micro-pores are required. Two MEMS techniques were used to fabricate x-ray optics with curvilinear micro-pores; however, the resulting curved sidewalls were too rough to reflect x-rays. To solve this issue, an ultra-precision polishing process employing alternating magnetic field assisted finishing was proposed. A processing principle was devised using a magnetic abrasive fluid mixture and an alternating and switching magnetic field. The concept involves two coaxial, inward facing, magnetic poles. The micro-pore optic is submerged in the fluid mixture and placed between the poles. The fluid mixture oscillates from pole to pole, flowing through the optic's micro-pores, thus polishing the sidewalls. A machine was constructed to realize this principle on miniature work pieces called mirror chips (7.5 mm^2 wafers with micro-pores). The effects on sidewall roughness of several process parameters were studied, and improvements in micro-pore sidewall roughness were seen. The x-ray reflectance of the polished mirror chips was also confirmed.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Raul Riveros.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Greenslet, Hitomi.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024588:00001


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Iwouldliketothankmyparents,asIwouldbenothingwithouttheireverlastingdedication,support,teachings,andlove.Iwouldalsoliketothankmyawesomeadvisor,Dr.HitomiYamaguchiGreenslet,forbelievinginandworkingwithme;Ibelieveitisagreathonortoworkwithher.IwouldliketothanktheDr.TonyL.Schmitzwhograciouslywelcomedmeintohislabandassignedmetoprojectswhichreadiedmeformygraduatestudy.IalsowanttothankDr.JohnK.Schuellerforlettingmeintograduateschoolandbeingonmycommittee.IwishtothankourpartnersinJapan,Dr.YuichiroEzoe,IkuyukiMitsuishi,MasakiKoshiishi,UtakoTagakiandFumikiKato,fortheirgreateortsincoordinatingandrealizingourgoals.AspecialthanksgoestoDr.JohnGreenslet,whoverykindlyeditedmywrittenwork.IwanttothankallmembersoftheMachineToolResearchCenter,particularlythosepresentfromJuly2006toMay2009;wewillallbebestfriendsforever(BFF). 4

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page ACKNOWLEDGMENTS ................................. 4 LISTOFTABLES ..................................... 7 LISTOFFIGURES .................................... 8 ABSTRACT ........................................ 11 CHAPTER 1INTRODUCTION .................................. 13 1.1X-RayAstronomy ................................ 13 1.2Background ................................... 13 1.2.1ReectionandRefractionofElectromagneticRadiation ....... 13 1.2.2X-RayReection ............................ 15 1.3X-RayTelescopes ................................ 16 1.3.1WolterType-IOptics .......................... 17 1.3.2TechnicalIssuesofExistingWolterType-IOptics .......... 18 1.4X-RayMirrorFabricationTechnologies .................... 19 1.4.1GlassSheetMirrors ........................... 19 1.4.2ThinFoilMirrors ............................ 20 1.4.3Micro-PoreMirrors ........................... 20 1.5MEMSTypeX-RayMirrorFabrication .................... 21 1.5.1AnisotropicWetEtching ........................ 21 1.5.2DeepReactiveIonEtching(DRIE) .................. 22 1.5.3X-RayLithography(LIGA) ...................... 24 2MAGNETICFIELDASSISTEDFINISHING ................... 26 2.1IntroductiontoMagneticFieldAssistedFinishing .............. 26 2.2StaticMagneticFieldAssistedProcess .................... 30 2.3AlternatingMagneticFieldAssistedProcess ................. 32 3DEVELOPMENTOFPROCESSPRINCIPLEANDPOLISHINGMACHINE 34 3.1Micro-PoreX-RayMirrors ........................... 34 3.2ProcessingPrincipleforMicro-PoreX-RayMirrorPolishing ........ 38 3.3DesignConceptandSpecicationsofPolishingMachine ........... 40 3.4PolishingMachine ................................ 40 3.4.1DesignandBuild ............................ 40 3.4.2DynamicMotionofFerrousSlurry ................... 43 5

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......................... 49 4.1SurfaceRoughnessAnalysis .......................... 49 4.2ExperimentalProcedure ............................ 51 4.3DRIE-FabricatedMirrors ............................ 53 4.3.1UnpolishedState ............................ 53 4.3.2EectsofDiamondSlurriesonPolishingCharacteristics ....... 55 4.3.3EectsofPolishingTimeonPolishingCharacteristics ........ 55 4.3.4EectsofFrequencyofMagneticFieldonPolishingCharacteristics 57 4.3.5EectsofMicro-poreWidthonPolishingCharacteristics ...... 59 4.3.6EectsofChemicalAssistanceonPolishingCharacteristics ..... 60 4.4LIGA-FabricatedMirrors ............................ 63 4.4.1UnpolishedState ............................ 63 4.4.2PolishingCharacteristics ........................ 65 5X-RAYREFLECTIONTESTING ......................... 67 5.1TestingMethod ................................. 67 5.2GrazingIncidenceX-RayScatteringandSpecularReectanceTestResults 68 6CONCLUSIONS ................................... 70 6.1ConcludingStatements ............................. 70 6.2FutureWork ................................... 70 APPENDIX:TESTINGPLAN .............................. 73 REFERENCES ....................................... 76 BIOGRAPHICALSKETCH ................................ 78 6

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Table page 3-1Machinespecications. ................................ 42 4-1Experimentalconditionsforabrasivesizetest. ................... 55 4-2Experimentalconditionsforpolishingtimetest. .................. 57 4-3Experimentalconditionsforoscillatingfrequencytest. ............... 58 4-4Experimentalconditionsformicro-porewidthtest. ................ 60 4-5Experimentalconditionsforchemicalassistancetest. ............... 62 4-6Experimentalconditionsfornickelmirrorchiptrial. ................ 65 A-1Experimentalconditionsforeachtestonsiliconmirrorchips. ........... 74 A-2Siliconmirrorchipsusedfortestingandtheirmicro-poredimensions. ...... 75 A-3Surfaceroughnessvaluesofsiliconmirrorchipmicro-poresidewalls ....... 75 7

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Figure page 1-1Schematicoftheelectromagneticspectrum. .................... 13 1-2Schematicofawavereectingandrefractingoasurface. ............ 14 1-3Schematicofgenericopticalfocusing. ........................ 17 1-4SchematicofWoltertype-Imirrorarrangement. .................. 18 1-5Schematicofacut-awayviewofaWoltertype-Inestedmirrorarrangement. .. 18 1-6Asimplediagramofnestedannularrings. ..................... 19 1-7Comparisonbetweenglass/foilmirrortypemirrorsandmicro-poremirrors. ... 21 1-8Schematicofwetetchingprocessow. ....................... 22 1-9SchematicofDRIEprocessow. .......................... 23 1-10SchematicofDRIEetchingmechanism. ....................... 23 1-11X-rayLIGAprocessow. .............................. 25 2-1Schematicofastandardwaferpolishingmachine. ................. 27 2-2SchematicofawaferpolishingprocessmodiedtouseMAF. ........... 28 2-3Schematicofprocessingprincipleforstaticmagneticeldpolishingprocess. .. 31 2-4Photographofstaticmagneticeldassistedinternalnishingequipment. .... 31 2-5Schematicofprocessingprincipleforalternatingmagneticeldassistedmachiningprocess. ........................................ 33 2-6Photographofalternatingmagneticeldassistedmachiningequipment. ..... 33 3-1PhotographofasiliconsinglestageWoltertypeIoptic. .............. 34 3-2Schematicofthefunctionofamicro-porex-raymirror. .............. 35 3-3Photographofasiliconmirrorchip. ......................... 36 3-4Photographofanickelmirrorchip. ......................... 37 3-5PhotographofaLIGAmoldforelectroplating. ................... 37 3-6Sizecomparisonbetweenafullopticandamirrorchip. .............. 38 3-7Two-dimensionalschematicofprocessingprinciple. ................ 41 3-8CADdesignofpolishingmachine. .......................... 42 8

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................................... 43 3-10Photographofcompletedpolishingmachine. .................... 44 3-11Workstationsetup. .................................. 44 3-12Originalelectriccircuitandatwo-dimensionalschematicofthecorrespondinguidbehavior. ..................................... 45 3-13Fluidmotionusingoriginalcircuit. ......................... 46 3-14Modiedcircuitandcurrentplot. .......................... 47 3-15Two-dimensionalschematicofuidbehaviorwithmodiedcircuitdesign. .... 47 3-16Fluidmotionusingmodiedcircuit. ......................... 48 3-17Schematicoftransientstatesofmagneticeldduringoperation. ......... 48 4-1Schematicofasurfaceprole. ............................ 49 4-2Schematicofasurfaceprolebrokendownintowavinessandroughness. .... 50 4-3Photographofexperimentalsetupwithamirrorchipmounted. ......... 52 4-4MicrographofanunpolishedDRIE-fabricatedmirrorchipmicro-poresidewall. 54 4-5Three-dimensionalshapeofunpolishedsiliconmirrorchipsidewallsurfacemeasuredbyanopticalprolometer. .............................. 54 4-6Surfaceroughnessresultsfromabrasivesizetests. ................. 56 4-7Three-dimensionalshapeofsiliconmirrorchipmicro-poresidewallsurfacesafterabrasivesizetestingasmeasuredbyanopticalprolometer. ........... 56 4-8Surfaceroughnessresultsfrompolishingtimetests. ................ 57 4-9Three-dimensionalshapeofsiliconmirrorchipmicro-poresidewallsurfacesafterpolishingtimetestingasmeasuredbyanopticalprolometer. .......... 58 4-10Surfaceroughnessresultsfromfrequencyvariationtests. ............. 59 4-11Three-dimensionalshapeofsiliconmirrorchipmicro-poresidewallsurfacesafterfrequencyvariationtestingasmeasuredbyanopticalprolometer. ....... 59 4-12Surfaceroughnessresultsfrommicro-porewidthtests. .............. 61 4-13Three-dimensionalshapeofsiliconmirrorchipmicro-poresidewallsurfacesaftermicro-porewidthvariationtestingasmeasuredbyanopticalprolometer. ... 61 4-14Surfaceroughnessresultsfromchemicalassistancetests. ............. 63 9

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....... 64 4-16Opticalprolometerdataforanunpolishedmirrorchip. ............. 64 4-17Opticalprolometerdataforapolishedmirrorchip. ................ 66 4-18Comparisonofsidewallsurfaceroughnessbeforeandafterpolishing. ....... 66 5-1Schematicofx-rayreectancetestingsetupformicroporemirrorchips. ..... 67 5-2X-rayreectancetestingsetup. ........................... 68 5-3X-rayreectancedataforapolishednickelmirrorchip. .............. 69 10

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Inrecentyears,x-raytelescopeshavebeenshrinkinginbothsizeandweighttoreducecostandvolumeonspaceightmissions.Currentdesignsfocusontheuseofmicro-electro-mechanicalsystems(MEMS)technologiestofabricateultra-lightweightandhigh-resolutionWoltertypeIx-rayoptics.In2006,Ezoeetal.introducedmicro-porex-rayopticsfabricatedusinganisotropicwetetchingofsilicon(110)wafers.Theseoptics,thoughlightweight(completetelescopeweightlessthan1kgforaneectiveareaof1000cm2),hadlimitedangularresolution,asthereectingsurfaceswereatcrystalplanes.Toachievehigherangularresolution,curvedmicro-poresarerequired. TwoMEMStechniqueswereusedtofabricatex-rayopticswithcurvilinearmicro-pores;however,theresultingcurvedsidewallsweretooroughtoreectx-rays.Tosolvethisissue,anultra-precisionpolishingprocessemployingalternatingmagneticeldassistednishingwasproposed.Aprocessingprinciplewasdevisedusingamagneticabrasiveuidmixtureandanalternatingandswitchingmagneticeld.Theconceptinvolvestwocoaxial,inwardfacing,magneticpoles.Themicro-poreopticissubmergedintheuidmixtureandplacedbetweenthepoles.Theuidmixtureoscillatesfrompoletopole,owingthroughtheoptic'smicro-pores,thuspolishingthesidewalls.Amachinewasconstructedtorealizethisprincipleonminiatureworkpiecescalledmirrorchips(7.5mm2waferswithmicro-pores).Theeectsonsidewallroughnessofseveralprocessparameterswerestudied;thisdemonstratedthefeasibilityoftheproposedprocessto 11

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InDecember2008,Ezoeetal.presentedthedevelopmentofanewclassofx-rayopticswhichwouldallowfortheconstructionofultra-lightweightandhighresolutionx-raytelescopes 1.2.1ReectionandRefractionofElectromagneticRadiation 1-1 Figure1-1. Schematicoftheelectromagneticspectrum. 13

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v(1{1) wherecisthephasevelocityofthewavethroughareferencemediumandviswave'sphasevelocitythroughthemediumwithwhichitisinteracting.Thephasevelocity,andthustherefractiveindex,ofawavethroughamediumdependsonboththemedium'spropertiessuchastheatomicscatteringfactoranddensityandthewave'spropertiessuchasitsenergyandelectric-eldvectororientation Figure 1-2 showsawaveimpingingonasurfaceandtwocomponents,thereectedwaveandtherefractedwave.Snell'slawrelatestherefractiveindicesofmediumsthrough Figure1-2. Schematicofawavereectingandrefractingoasurface. 14

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wheren1andn2aretherefractiveindicesoftwoadjacentmediumsand1and2aretheincidentandrefractedwaveangles.Astheangleofincidence,1,increases,aphenomenonknownastotalinternalreectionoccurs.Atacertaincriticalangle,c,thewaveceasestorefractintotheadjacentmediumandcompletelyreects.Totalinternalreectiononlyoccursifthemediuminwhichthewaveisoriginallyinhasahigherrefractiveindexthantheadjacentmedium(n1>n2).ThecriticalangleisfoundbyrewritingSnell'slaw( 1{2 )andsetting2=90 Totalexternalreectionisatermoftenusedtoidentifythetotalreectionofawaveoasurface.Thewave,inthiscase,istypicallytravelingthroughavacuum.Itisthesamephenomenonastotalinternalreection;however,thetermexternalimpliesthatthewaveinitiallytravelsfromthesurroundingsofthereectioninterface. whereisdierencebetweentherefractiveindexand1,isthematerial'sabsorptionindex,f1andf2aretherealandimaginarycomponentsofthematerial'satomicscatteringfactor,Natisthematerial'satomicdensity(atomsperunitvolume),r0istheradiusofanelectron,iistheimaginarynumber,andisthewavelengthofthex-rayradiation Ithappensthatallmaterialshaverefractiveindicesslightlylessthan1forx-rays.Suchvaluesforrefractiveindicesindicatethatx-rayreectionandrefractionisnotas 15

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Imagingx-rayshashistoricallybeenchallenging.Becausemostmaterialshaverefractiveindicesjustslightlybelow1,lensesareimpracticalasfocallengthswouldbeextremelylong.Practically,themostecientwaytochangethedirectionofanx-rayisthroughtotalexternalreection.X-raylensesaredesignedtoemploythetotalexternalreectionofx-rayssoastofocusthemtoapointontoadetectorforimaging.Therearemanydesignsinexistence;however,thedesignofx-raytelescopesoperatinginouterspaceisrelevanttothisdocument. X-rayopticsshouldbeabletoproperlyfocusx-raysecientlywithoutdistortingtheincomingx-rayradiationsuchthatthedetectedimageaccuratelyrepresentstheincomingsignals.Intheory,reectionoaperfectlyatandsmoothsurfaceproducesspecularreection(clear,undistorted).Reectionoaroughsurfacewouldproducediusereection(blurred,distorted).Inpractice,totalexternalreectionisdiculttoachieveduetotheroughnessofthereectingsurfaces.Thus,tomaximizethereectingcapabilityofasurfaceitshouldachieveasmuchspecularreectionaspossibleandhavemaximumreectedwaveintensity.Toachievespecularreection,thereectingsurfacesmustbeassmoothaspossible.Tomaximizetheintensityofthereectedwave,theangleofincidenceshouldbeaslargeastechnicallypossible.Suchextremelyincidenceanglesareknownasgrazingincidence. 16

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1-3 ,tosuccessfullyformanimage,itsgeometricarrangementmustsatisfytheAbbesinecondition,statedin( 1{5 ). Thisequationmustbetrueornearlytrueforproperimageformation.Therefore,afunctionalx-rayopticalsystemmustnotonlyachieveecientx-rayreection,butitmustalsosatisfytheAbbesinecondition Figure1-3. Schematicofgenericopticalfocusing. 1-4 showsWolter'stype-Ix-rayopticalarrangement.ThisarrangementnotonlyallowsfortotalexternalreectionothereectingsurfacesbutalsonearlysatisestheAbbecondition.Theuppermirrorsarecontouredtofollowaparaboloidwhilethelowermirrorsarecontouredtofollowaconfocalhyperboloid.Inactuality,telescopescontainmanynestedlayersofmirrorsasshowninFigure 1-5 .Suchanarrangementallowsforgreaterdetectionarea 17

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SchematicofWoltertype-Imirrorarrangement. Figure1-5. Schematicofacut-awayviewofaWoltertype-Inestedmirrorarrangement. 1-6 .TheareabetweentheblackannularregionsinFigure 1-6 isduetothethicknessofthereectingsurfaces.Thethicknessofthereectingsurfacescausesaradialdiscontinuityinthecapturedimage.Also,supportstructuresfortheinnernestedmirrorsetscauseangulardiscontinuitiesaswell. Thenextmajortechnicalissueisweight.X-raytelescopesintendedforastrophysicsresearchmustoperateinouterspace.Thus,theyneedtobetransportedbyarocket.The 18

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Asimplediagramofnestedannularrings. costperunitweightfortransportingasatelliteintospaceisextremelyhigh($10Kperkg);therefore,itisimportantthatthetelescopebeaslightaspossible.ExistingWoltertype-Ix-raytelescopestendtobelargeandheavy,fortheyrequireprecisehardwareandsupportstructures. 19

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1-7 showsacomparisonbetweenmicro-poreandglass/foiltypemirrors.Essentially,theseopticsconsistofasubstratewiththrough-pores;theporesidewallsareintendedforuseasgrazingincidencemirrors.Reducedreectingsurfacethicknesswillallowforbetterimaging.Micro-poreoptics,ifrealized,couldallowfortheconstructionoffullycapablex-raytelescopesweighingapproximately1kg Micro-porex-rayopticsarefabricatedusingtechniquescommonlyusedforthemanufacturingofmicro-electro-mechanicalsystems(MEMS).Therearethreetechniqueswhichcanbemostusefulforcreatingmicro-porex-rayoptics;theywillbedescribedinthenextsection. 20

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BMicro-poremirror Comparisonbetweenglass/foilmirrortypemirrorsandmicro-poremirrors. 1-8 .Thewetetchingofsiliconinvolvescoatingasiliconwaferwitheithersiliconnitrideorsiliconoxideonbothsides(topandbottom).Alayerofphotoresistisplacedonthetopcoat.Usingultravioletradiation(UV)andaUVmask,thecoatingonthetoplayerisexposedtotheUVradiation.Thephotoresististhendevelopedandthetoplayerofsiliconnitride/oxideisetched.Theremainingphotoresistisremovedandthesiliconwaferisnowmaskedonlyby 21

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Figure1-8. Schematicofwetetchingprocessow.[CourtesyofYuichiroEzoe] Thistypeofetchingisanisotropic.Thislimitsittoetchingonlystraighttrenchesalongthesilicon'scrystalplanes,renderingonlystraightmicro-pores.Ezoeetal.presentedmicro-poreopticsmadeusingthiswetetchingtechnique.Intheireort,anultrasonicwavewasusedduringtheetchingofthesilicontoimprovetheresultingmicro-poresidewallroughnesstolessthan1nmrms.Theseopticsthereforehadexcellentspecularreectionofx-rays;however,theyhadlimitedangularresolutionasthereectingsurfaceswereatplaneswhichdoesnotcomplywithatrueWoltertype-Iopticdesign 1-9 .Alayerofphotoresistisplacedonasiliconwafer.UsingaUVmaskandUVradiation,themaskisexposedtotheUV.The 22

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Figure1-9. SchematicofDRIEprocessow. TheactualDRIEmechanismhastwophasesasshowninFigure 1-10 .First,thesiliconisexposedtouorineionswhichreactwiththesiliconandcreateSiF4gas,thisiscalledthe"EtchingMode".Thentheexposedsiliconiscoatedina(-CF2-)polymer,thisiscalledthe"PassivationMode".Thispolymercoatingprotectsthetrenchsidewallsfromfurtheretchingandundercutting.Theprocessisthenrepeateduntilthedesiredetchingdepthisreached. BPassivationmode SchematicofDRIEetchingmechanism. 23

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1-11 beginswithasheetofpolymethylmethacrylate(PMMA)andamaskcapableofobscuringx-rays.ThemaskisplacedoverthePMMAsubstrateandthesetupisexposedtosynchrotronradiation,namelyhighenergy(hard)x-rays.TheradiationtendstodestroythePMMAstructure.Theaectedareasarethenremovedwithachemicalsolution TherearesomeadvantagestofabricatingmicrostructureswithLIGAasopposedtoetching.LIGAallowsfortheproductionofhighaspectratiostructures.Alsothesidewallsoffeaturesareverystraightandtypicallyhaveasurfaceroughnessofabout10nmrms 24

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LIGAprocessow.[CourtesyofYuichiroEzoe] 25

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, 14 ThereareseeminglyendlesswaysinwhichMAFcanbeapplied;however,allsetupspossessimilarcomponents.Allsetupsincludeoneormorepermanentmagnetsorelectromagnets.Theyalsoincludeaferromagneticentitywhicheitherhasabrasivepropertiesitselforisincontactwithalooseabrasive.MAFsetupsalsohaveameansofachievingrelativemotionbetweenthecuttingedgesoftheabrasiveparticlesandthesurfaceintendedfornishing. TherearemanyadvantagestousingMAFinsteadofconventionaltechniques,buttherearealsosomeapplicationsinwhichMAFistheonlysuitablenishingtechnique.PerhapsthemostprominentadvantageofMAFisthatitallowsfornishingofsurfacesinaccessiblebyconventionaltechniques.Forexample,insystemswherecleangasisused,thepipingandrellsneedtohavesmoothsurfacesinsidetopreventcontaminationbydepositionofforeignsubstances.ShinmuraandYamaguchiusedMAFtosuccessfullypolishtheinsideofacleangasrell.Theinsidesurfacewouldnormallybedicultifnotimpossibletoaccesswithaconventionalpolishingtoolbecauseitisnotpossibletoinsertthetoolthroughtherell'ssmallopening.Instead,therellwaspartiallylledwitha"mixed-type"magneticabrasive.Thismagneticabrasiveisamixtureofironparticlesandabrasiveparticles.Permanentmagnetsoutsideoftherellwereheldstationaryasthe 26

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AnotheradvantageofMAFisthenon-rigidlinkbetweentheactuatingentityandtheabrasivecuttingedges.ThisoccurrenceisperhapsbestillustratedbyanexampleinwhichastandardwaferpolishingmachinesetupisconvertedtoemployMAF.InFigure 2-1 ,anormalwafersingle-sidedpolishingsetupisshown.Thewafertobepolishedsitsatoparotatingtable.Abrasiveslurryisplacedbetweenthepolishingpadandworkpiece.Amechanicalarmappliespressuretothepolishingpad,maintainingitstationaryasthetableandworkpiecerotate. Figure2-1. Schematicofastandardwaferpolishingprocess. TheprocessinFigure 2-1 canbereconguredtouseMAF.ThereconguredprocessisshowninFigure 2-2 ;thisissimilartothesetupusedbyYamaguchietal.in2009 27

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2-1 ,doesnothavearigidlinkbetweenthemagnetandtheabrasiveparticles.Thismeansthatanyvibrationsfromtherotatingplate,supportstructureofthemagnetarenotdirectlytransmittedwhereasinastandardpolishingmachine,anyvibrationsinthetableormachinewillbetransmittedtotheabrasiveandsubsequentlytotheworkpiece.Thisnon-rigidlinkallowsformoreprecisesurfacesandsmoothernishes.Thissortofimprovementisrequiredintheareaofquartzorlenspolishing,asanydefectsinthesurfaceoftheelementtendstoreducethelifeofthepart.Thenon-rigidlinkofMAFprovidesagentlernishingprocess,reducingtheamountofsurfacedamagefromthenishingprocess Figure2-2. SchematicofawaferpolishingprocessmodiedtouseMAF. MAFisahighprecisionsurfacenishingprocesscapableofnishingconventionallyinaccessiblesurfaces.Itisknownasaformfollowingandpressurecopyingprocessasthepolishingtoolstendtobeexibleandcanchangeinlengthinsituwithoutaectingthenishingproperties;thisisknownasthe"exiblebrush"createdbythealignmentofferromagneticparticlesalongthemagneticlinesofforceinamagneticeld.Thechallengesofpolishingofcomplexsurfaces(contoured,textured)aresometimeseasilyovercomewithMAF. Theforcetotalforceofamagnetictoolactingonasurfacecanbecalculatedusingthefollowingrelationship: 28

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ThereissomevarietyofferromagneticcomponentsusedinMAFprocesses;theseinclude:magneticabrasives(ferrousparticleswithabrasiveparticlesaxedtotheirsurface),ironpowder,magneto-rheologicaluid(MRF),andmagneticuid(MF).MRFisamixtureofsmall(5mdiameter)ironparticlesandeitherahydrocarbonorsiliconbasedoil.MRF,whensubjectedtoamagneticeld,becomesmoreviscous.Thispropertyallowsittobecontrolledinapplicationssuchaslenspolishingwherethenishingpressureneedsprecisecontrol.MRFisusedtopolishsurfacestoangstromorderroughness MFisasuspensionofnanoscalemagnetiteparticles(10nmdiameter)inwater.TherehavebeensuccessfulattemptsatpolishingwithMF 29

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MAFhasbeenshowntobescalable;ithasbeenappliedtonormalsizedworkpiecesaswellastomicro-scaleworkpieces.Thefollowingsectionswilldetailtwoprocesseswhicharerelevanttothisresearch,fortheyshowthescalabilityofMAFandtheuseofanalternatingmagneticeld. Figure 2-3 isaschematicoftheprocessingprincipleforcapillarytubepolishing.Asseen,thetubecontainsasmallamountofmagneticabrasive.Thetuberotateswhilethemagneticcomponentsreciprocateparalleltothetube'saxis.Themagneticcomponentsconsistofapermanentmagnetslinkedbyapieceofferromagneticmaterial,inthiscasecarbonsteel,whichactsasamagneticyoke.Theyoketendstoincreasethemagneticeldstrength.Alsoattachedtothepermanentmagnetsareferromagneticdevicescalledmagneticpoletipswhichconcentratetheeldattheirnarrowtips.Suchgeometryallowsformoreprecisecontroloftheabrasiveandallowsforthepolishingofsmalldiametertubes. 30

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Schematicofprocessingprincipleforstaticmagneticeldpolishingprocess.[CourtesyofHitomiYamaguchi] Figure2-4. Photographofstaticmagneticeldassistedinternalnishingequipment.[CourtesyofHitomiYamaguchi] Figure 2-4 isaphotographofthecapillarytubepolishingmachinesetup.Themotorandchuckassemblywhichholdtheassemblyareseen.Alsothemagneticcomponentsareseenmountedonatwoaxismanualstageforproperpositioningofthepoletipsrelativetotheworkpiece.Themagneticcomponent/stageassemblyismountedontoamotorizedlinearstagewhichisthenprogrammedtoreciprocatethemagneticcomponent/stageassemblyparalleltothetube'saxis ExperimentsconductedwiththismachinedemonstratedthattheinnersurfaceofSS304stainlesssteeltubesof400minnerdiameterhavinganinitialsurfaceroughnessof 31

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Figure 2-5 showstheprocessingprincipleforthisprocess.Asshown,therearetwoelectromagnetsfacingeachother;thecoilsaresuppliedwithalternatingcurrentinaparallelcongurationwhichcreatesanalternatingmagneticeld.Apipeisclampedonachuckjustbeneaththeelectromagneticpoletips.ThemagnetictoolsusedinthiscaseareSS304stainlesssteelpins,formedbycuttingawireinto2.5and5mmsegments.AlthoughSS304stainlesssteelisaparamagneticalloy,coldworkingcausesachangeinmicrostructure,allowingthepinstobecomemagnetized.Thecoldworkedpinswillnaturallyalignthemselveswiththemagneticelddirection.Therefore,iftheeldisalternating,thepinswillcontinuallyrealignthemselveswiththeelddirection.Ifthealternatingfrequencyishighenoughandifthepinsweresomehowsuspended,theywouldrotateinareciprocatingfashion.Thepins,however,arenotsuspended;instead,theyareplacedinsidethetube.Whenanalternatingeldisappliedtotheworkingarea,thepinsbegintorotateandessentiallyjumpotheinnertubesurface.Theresultsisaseeminglychaoticmotionwiththepinsconstantlystrikingtheinnertubesurface,thuscreatingregionsofcompressivestresses(dents). Figure 2-6 showsaphotographofthemachine.Theopposingelectromagnetsarevisibleasistheworkpiece.Thefunctiongeneratorcreatesthealternatingcurrentfortheelectromagnets.Alsotheelectromagneticpoletipsareshownwithclearanceslabeled.This 32

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Schematicofprocessingprincipleforalternatingmagneticeldassistedmachiningprocess.[CourtesyofHitomiYamaguchi] processwasabletosuccessfullyraisethehardnessandcompressiveresidualstressesoftheinnertubesurface.ThisisanexampleofanalternatingMAFprocessforasurfacetexturingapplication. Figure2-6. Photographofalternatingmagneticeldassistedmachiningequipment.[CourtesyofHitomiYamaguchi] 33

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3-1 showsaphotographofanx-raymirrormadebyJAXA.Thissiliconmicro-porex-raymirroris100mmindiameterandonly300mthick.Theslitsare5-20mwideandvaryinarclengthfromlessthan1mmtonearly10mmandextendthroughthethicknessofthesiliconsubstrate;theslitswerecreatedbyDRIEonacommerciallypurchasedhighqualitysiliconwafer. Figure3-1. PhotographofasiliconsinglestageWoltertypeIopticfabricatedbyDRIE. ThemirrorsfunctionisbrieyexplainedinFigure 3-2 .Themirrorintop-viewrepresentsthemirrorfromFigure 3-1 .Ascanbeseenfromthecross-sectionalview,theslitsaretoincreaseinwidthastheradiusincreases.ThelowermostgraphicinFigure 3-2 showsthemirrordeformedsothatthemicro-poresidewallsareangledsuchthatincidentx-raysarespectrallyreectedandfocusedontoapoint.JAXAisincollaborationwithanothergroupatTohokuUniversityinJapanwhohasbeenabletoplasticallydeform 34

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3-1 ,givingitasphericalshapehavingaradiusofapproximately1000mm. Figure3-2. Schematicofthefunctionofamicro-porex-raymirror. AlthoughJAXAcancreatethemirrorandTohokuUniversitycandeformthemirrortothedesiredsphericalshape,themicro-poresidewallroughnessistoohightoattainspectralreectionofincidentx-rays.ThisisnotanunexpectedresultastypicalroughnessforthesidewallsoffeaturescreatedbyDRIEisaround30nmrms Toattempttosolvethesidewallroughnessdilemma,JAXAprovidedminiatureworkpieceswithmicro-poresetchedonthemofsimilargeometrytothefull-sizemicro-porex-raymirror.Theseminiatureworkpiecesarecalled"mirrorchips"andaphotographofasiliconmirrorchipisshownFigure 3-3 .Themicro-porewidthisconstantonthesemirror 35

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Figure3-3. PhotographofasiliconmirrorchipfabricatedbyDRIE. JAXAiscollaboratingwithFumikiKatoofRitsumeikanUniversityinJapantofabricatenickelmirrorchipsbyx-rayLIGA.Mr.Katowasabletofabricatealimitednumberofnickelmirrorchips.AphotographofanickelmirrorchipfabricatedbyLIGAcanbeseeninFigure 3-4 .AlthoughthesidewallsurfaceroughnessofnickelstructuresmadebyLIGAisbetter(10nmrms 3-5 ,thePMMAmoldfromtheLIGAprocessisshown;thisisbeforethemoldissputteredwithgold.Toclarify,themoldseeninFigure 3-5 istheatstep3inFigure 1-11 Figure 3-6 showsasidebysidecomparisonbetweenthefull-sizex-raymirrorandasiliconmirrorchip.Oncetestingiscompleteonmirrorchipsandasuitablemicro-poresidewallsurfaceroughnessisachieved,attemptsatpolishingafull-sizex-raymirrormaybegin. 36

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PhotographofanickelmirrorchipfabricatedbyLIGA. Figure3-5. PhotographofaLIGAmoldusedtocreateanickelmirrorchip.Thisisanexampleofthemolddescribedinstep2ofFigure 1-11 37

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Sizecomparisonbetweenafullopticandamirrorchip.BothstructuresshownaremadeofsiliconandfabricatedbyDRIE. 38

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Micro-pores,withregardtothemicro-porex-raymirror,rangeinwidthfrom5to20m.Thelowerlimitof5mrulesouttheuseofanymagneticabrasiveparticles,ironpowdersormagneto-rheologicaluid(MRF)asaferromagneticcomponentoftheMAFprocessastheyrangeinsizefrom5mtohundredsofmicrons.Theonlyferromagneticcomponentneenoughtoworkinsidemicro-poresismagneticuid(MF).Thesmallslitwidthalsolimitsthesizeofabrasivethatcanbeused;fortunatelythough,therearecommerciallyavailableabrasiveshavingameanparticlediameterassmallas50nm. Choicesforamagneticabrasivecombinationofmaterialswereratherlimited.MFiscommerciallyavailableandiscommonlybasedineitherkeroseneorwater.WaterbasedMFwaschosenforthisapplicationbecauseitrinseseasilyandwithoutresidue;waterbasedMFismoreenvironmentallyfriendlythankerosenebasedMF.Throughtrialanderror,itwasfoundthatMFdoesnotmixeasilywithcommercialpowderabrasivesbecauseagglomerationofparticlesoccurs.Italsodoesnotmixwellwithcommercialabrasiveslurriesasittendstoformaprecipitate.Itwasfoundthatitonlymixeswellwithsomewaterbasedabrasiveslurries(dependingonthemanufacture'sspecicsurfactants)andwithuniversalabrasiveslurrieswhichareabletohomogeneouslymixwithbothwaterandoilbaseduids. ThebasicconceptofaprocessingprincipleinvolvedusingamixtureofMFandabrasiveslurryasamagneticabrasive.Thismixturewouldbeplacedinsidetheslitsandamagneticeldwouldbeusedtoforcethemixtureonthemicro-poresidewallstopolishthem.Toplacethemagneticabrasiveuidinsidethemicro-poreslits,themirrorwastobesubmergedinthemagneticabrasiveuid.Inordertopolishthemicro-poresidewalls,therehadtoberelativemotionbetweentheabrasivecuttingedgesandthemicro-pore 39

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TheprocessingprincipleshowninFigure 3-7 wasconceived.Inanalternatingmagneticeld,thestrengthanddirectionaretransient.Torepresenttheprocessschematically,twostateswerechosen:State1andState2.Thesestatescorrespondtothepointsintimewherethemagneticeldstrengthisatitsmaximuminbothdirections.Thealternatingmagneticeldiscreatedbytwocylindricalelectromagnetsfacingeachothercoaxially,asinthemachinedescribedinsection2.2.Themirrorchipispositionedsuchthatitslargeatfacesareperpendiculartotheelectromagnet'saxis.Inthisarrangement,theuidshouldessentiallymovefromoneelectromagnettotheotherrepeatedly,thuspolishingthemicro-poresidewalls. Theserequirementsarebroad;amorespecicdescriptionisoeredtheTable 3-1 .Inthenextsection,theactualmachinedesignwillbepresented. 3.4.1DesignandBuild 3-8 .Thedesignfeaturesinterchangeablemagneticpoletipsanda 40

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Two-dimensionalschematicofprocessingprinciple. magneticyoke,delineatedinFigure 3-9 .Bothelectromagnetsaremountedonlinearbearingsandareactuatedbyadoublethreadedleadscrew(halfrighthandthread,halflefthandthread).Thisstagesetupallowstheelectromagnetstomovesymmetrically,creatingspaceonbothsidesoftheworkareaforeasieraccess.Adigitallinearscaleisattachedtobothelectromagnetstagesandreadstheinter-polegap.Thethreeaxismanualstageisavailableforworkpiecejigmounting.Adjustablemachinefeetallowthemachinetobeleveled. Figure 3-9 showsthemagneticcomponentsofthemachineoutlinedinred.Thepoletipsaredesignedtoincreasethestrengthofthemagneticeldattheinter-polegap.The 41

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Machinespecications. Feature PropertyDescription Electromagnets InterchangeablemagneticpoletipsAttachedusingathreadedstud. Adjustableinter-polegapElectromagnetsmountedonlinearbearingsandarepositionbyaleadscrew.Magneticeld AlternatingAnACpowersupplyconnectedtoelectromagnetterminals. ControllableAexiblecircuitabletochangethecircuitfromparalleltoseries.ACpowersupplycanvaryvoltageandfrequency.Workpieceholder PreciseandadaptableAthreeaxis-manualpositioningstagewith50mmtravelineachaxiswithcoarseandnepositionadjustmentallowsformanymountingoptions. Figure3-8. CADdesignofpolishingmachine. 42

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Figure3-9. MagneticcircuitisshowninthisCADmodel.Themagneticcomponents(pole-tips,coilcores,andyoke)aredelineatedinred. Figure 3-10 isaphotographofthecompletedmachine.Figure 3-11 showstheexperimentalsetupwhichincludesthemachineandpowersupply.ThepowersupplyisaKikusuimodelPCR1000LA.Thispowersupplyisactuallyahighcurrentsignalgeneratorabletosupplyavarietyofwaveformsatseveralamperes.ThefrequencyrangeforACcurrentis0to1000Hz.ItisthereforesuitableforanexperimentalelectromagnetsetupsuchastheoneinFigure 3-10 becauseitallowsforexperimentationwithdierentwaveformstoforcedierentdynamicresponsesfromthemagneticabrasiveuid. 43

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Photographofcompletedpolishingmachine. Figure3-11. Workstationsetupincludingcompletedmachine,powersupply,andsurfaceplate. 44

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TheproblemlaidintheoriginalcircuitdesignshowninFigure 3-12 .Thetwoelectromagnets(coils)aresuppliedcurrentinparallel.Itisclearfromexaminingthecurrentowthrougheachelectromagnetthateachcoilreceivesthesamewaveform.Whenthecurrentwaveformisatitscrest,bothelectromagnetsaregeneratingmagneticeldsatfullstrengthandinadirectiondeterminedbytheirwiring.Theelectromagnetsarebothatfullstrengthatthetroughofthesuppliedwavebuttheirmagneticelddirectionsareswitched.Inotherwords,theelectromagnetsarebehavingsymmetrically. BSchematicofuidbehavior Originalelectriccircuitandatwo-dimensionalschematicofthecorrespondinguidbehavior. TheeectthatthissymmetricalelectromagnetbehaviorontheuidbehaviorisdescribedinFigure 3-12 .Theuidtakesonasymmetricalbehavior.Asseen,aportionofuidisplacedinsideaplastictesttubeandthetubeispositionedbetweenthemachine'spoletips.Figure 3-13 isastillframefromavideotakenofthedynamicuidmotion.The 45

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3-7 Figure3-13. Fluidmotionusingoriginalcircuit.[Conditions:MF1mL,1A,16Hz,Pole-poledistance12mm] Analternatingmagneticeldisnotnecessarytoachievethisuidbehavior;supplyingthecoilswithsinusoidalcurrentrangingfromnocurrenttomaximumcurrentwouldaccomplishthesamemacroscopicuidbehavior.ItisknownthatMFdoesnotexhibitanyhysteresisorcoerciveforce Amodicationwasrequiredtomaketheuidbehaveasintended.Achangetothecircuitwasmade;thismodiedcircuitisshowninFigure 3-14 .Asetofdiodeswereincludedinthecircuittomodifythecurrentowtobothelectromagnets.Insteadofeachcoilreceivingafull-wave,eachcoilnowreceivesanoppositehalf-wave.AplotofthisbehaviorisshowninFigure 3-14 .ItwasthoughtthatthiselectriccircuitwouldrealizetheprocessingprincipleofFigure 3-7 ,asonlyonecoilisactiveatatime,allowingforState1andState2toexist.AschematicoftheuidbehaviorobservedisshowninFigure 3-15 .Insteadofsymmetricalmotion,theuidnowisattractedtoonlyonesideatatime. AphotographofState1andState2oftheuidmotionisshowninFigure 3-16 .Theuiddoesnotexhibitsymmetricalmotion.Afewpreliminarypolishingtrialsusingthemodiedcircuitdidindeedcausesignicantmaterialremovalaschangesinsurfaceroughnesswereobserved. 46

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BCurrentbehaviorofmodiedcircuit Modiedcircuitandcurrentplot. Figure3-15. Two-dimensionalschematicofuidbehaviorwithmodiedcircuitdesign. Thismodiedcircuitchangesthefunctionofthemachine.Insteadofcreatingapurelyalternatingeld,themachinenowcreatesanalternatingandswitchingeld,wheretheterm"switching"impliesthat,atcertainpointsduringthemachine'soperation,onlyoneelectromagnetisactive.Sincethemagneticeldgeneratedbythemachineistransient,itisbesttorepresentitsbehaviorusingthepreviouslydenedstates1and2asshowninFigure 3-17 .InState1,theleftcoilisactiveandthearrowsindicateoftheowofmagneticux.InState2,onlytherightcoilisactive.ItisimportanttonotethatState 47

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BState2 Fluidmotionusingmodiedcircuit.[Conditions:MF1mL,1.4A,2Hz,Pole-poledistance15mm] 1andState2correspondtothecurrentstatesat20msand40msofthesimulationinFigure 3-14 BMagneticeldat40msofsimulation Schematicoftransientstatesofmagneticeldduringoperation. 48

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Theproler,usingtheavailablemagnication,isabletoimageanareaassmallas176133mwith640480lateralresolution.Thedataistypicallyanalyzedasamap(area)ofsurface.Fromthismap,surfaceroughnessvaluessuchastheroughnessaverage(Ra),root-mean-squaredroughness(rms),andpeaktovalleydistance(PV)arecalculated.Figure 4-1 showsaschematicofaproleofasinglelineofdatapointswithexamplesofroughnessvalues.TheRavalueisasimpleaverageofthedistanceofall Figure4-1. Schematicofasurfaceprole. pointsfromthecenterline.TheRavalueiscalculatedasfollows, whereyxaretheheightvaluesofameasureddatapoint,andNisthenumberofdatapoints 49

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whereyxaretheheightvaluesofameasureddatapoint,andNisthenumberofdatapoints ThePVvalueissimplythedierencebetweenthehighestpointtothelowestpointinthemaporprole.Thisfactorisusedtodescribethequalityofthesurface.Forexample,ifapolishingprocessleavesagenerallysmoothsurfacebutsuersfromagglomerationofabrasiveparticlescausingoccasionaldeepscratches,thenthesurfacewillhavelowRaandrmsvalues,butitwillhaveahighPVvalue. Anydeviationsonarealsurfacefromaperfectlyatsurfacearereferredtoassurfaceerrors.Surfaceerrorsareoftentimesperiodicinnatureandtheirwavelengthcanbemeasured.Surfaceerrorsaretypicallyclassiedintotwomajorwavelengthgroups,wavinessandroughness.Figure 4-2 showstherelationshipbetweenthesetwoclassications;theboundariesdeningthedierencebetweenwavinessandroughnessaredeterminedbytheintendedapplicationofthesurface. Figure4-2. Schematicofasurfaceprolebrokendownintowavinessandroughness. 50

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4-3 .Themirrorchipclampistwothin(0.5mm)plateswithanopeningmilledouttoexposethemirrorchip'smicro-pores.Oneoftheseplateshasasquareinsetareatoaccountforthemirrorchip'sthicknesswhenclampedbetweenthetwoplates.AnM3threaded316L(paramagnetic)stainlesssteelboltclampsthetwoplatestogetheratoneend.Thehandleissimplyanaluminumrectangularprismwithadeepslotgoingthroughoneofitsends.ThemirrorchipclampslidesinsidethisslotandanM4threaded316Lstainlesssteelboltclampstheotherendofthemirrorchipclampinthehandle'sslot. Oncethemirrorchipisclampedinthemirrorchipclampandthatassemblyisclampedinthehandle,thewaferandholderassemblyisplacedinsideatesttube.Thetesttubeisthenplacedbetweenthepolishingmachine'spoletips.Torunanactualtest,thetubeislledwiththemagneticabrasiveuidbeforethemirrorchip/holderassemblyisplacedinside.Itisimportanttonotethatthelevelofthemagneticabrasiveuidrelativetothemid-heightofthemirrorchipshouldbecoincidentbeforethealternatingandswitchingmagneticeldisapplied. Oncethemirrorchipisbothmountedonthemachineandpartiallysubmergedinmagneticabrasiveuid,thepowersupplyispoweredon,activatingthemagneticeld. 51

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Photographofexperimentalsetupwithamirrorchipmounted. Theuserwillexaminetheuidagitationvisuallyanddetermineiftheamountofagitationissucient,asthecurrentassumptionisthatmaximumuidmotionisdesiredforthemostecientnishing.Typically,ifmoreagitationisneeded,thewaferholderassemblyispulledoutofthetesttubeasmalldistance(1-2mm).Iflessagitationisneeded,thewaferholderassemblyispositioneddeeperinsidethetesttube.Thewaferassemblytsinsidethetesttubewithaslightinterference,itisthistthatallowsthewaferholderassemblytobepositionedasseentbytheuser. Regardingthemagneticabrasiveuid,itisproducedbyrstplacing1mLofMFinsidethetesttube.Next,1mLofabrasiveslurryisplacedinsidethetubeaswell.Theuserwillhomogenizethemixturebybrisklywavingastrongpermanentmagnetoutsideofthetube;thiscausestheuidstomixwell.Inthefollowingsectionaseriesofexperimentsdoneonsiliconmirrorchipsispresented.Itshouldbeknownthateverypolishingtrial 52

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4.3.1UnpolishedState Figure 4-4 showsamicrographofanunpolishedDRIE-fabricatedmirrorchipmicro-poresidewall.Asseeninthegure,thesurface'stexturevariesintheetchingdirectionandinthedirectionperpendiculartotheetchingdirection.Duetothisnon-uniformsurfacetexture,asinglemeasurementoftheentiresurfacewouldnotaccuratelyrepresenttheroughnessofthesidewall.Instead,onlyan80m2areawasusedforroughnessanalysis.Thisareaisplacedintheapproximatecenterofthesidewallsurfacewherethetexturetendsbemoreuniform. Figure 4-5 showsanobliqueplotfromameasurementtakenofanunpolishedmirrorchipmicro-poresidewallwithanopticalproler.Roughnessvaluestendtorangefrom10nmrmsto15nmrmsdependingonwherethemeasurementistaken.Thismeasurement'speaktovalley(PV)readingwas100nm.Thewaferssuppliedweresortedintogroupsrstbymicro-porewidth,thenbymicro-porespacing,andnallybyradius.Havinggroupedthewafers,atestingplanwascreatedtoexaminetheeectsofvariousprocessparameters. 53

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MicrographofanunpolishedDRIE-fabricatedmirrorchipmicro-poresidewall. AlistingofthistestingplanisshowninAppendixA.Thefollowingsectionswilldetailtheexperimentalconditionsandresultsfromthisseriesoftests. Figure4-5. Three-dimensionalshapeofunpolishedsiliconmirrorchipsidewallsurfacemeasuredbyanopticalprolometer. 54

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Experimentalconditionsforabrasivesizetest. Workpiece Simirrorchip7.50.2mmPoresize201500mAbrasiveslurry Diamondslurry0-0.5m,0-0.2m,0.05m(meandiameter)Suppliedamount:1mLMagneticuid WaterbasedmagneticuidSuppliedamount:1mLPole-Poledistance 15mmMagneticuxdensity 65.5mTAlternatingcurrent 1A,25HzPolishingtime 60min 4-1 liststheparametersusedinthisexperimenttoseetheeectsonsurfaceroughnessofdierentdiamondslurries.Figure 4-6 containstwoplotsdisplayingthemeasuredsurfaceroughnessunderanautomaticrobustgaussspline(coarse,cuto:8m)lterandanaveraging(ne,cuto:0.82m)lter.Figure 4-7 showsobliqueplotsofthemeasuredsurfacesafterpolishingwithdierentabrasiveslurries. InFigure 4-6 adenitetrendisobservedinthecoarselteredplot.Astheabrasivesizeincreases,theroughnessdecreases.Underacoarselter,largerabrasiveparticleswillappeartoremovelargersurfaceerrors.Theroughnessviewedunderanelterhoweverdoesnotexhibitthesametrend.Theabrasivesizeseemstohavenoeectontheroughnessatthisscale. 4-2 showstheexperimentalconditionsforthisexperiment.Figure 4-8 showstheroughnessresultsunderbothacoarseandanelter.Figure 4-9 showsthesurfaceprolerdataforeachpolishedmirrorchipintheformofobliqueplots. ConsideringthecoarselterplotofFigure 4-8 ,thepolishingprocessappearstonotimproveinsurfaceroughnessafter1hour.Thenelterdoesnotfollowthesametrend; 55

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BAveraginglter Surfaceroughnessresultsfromabrasivesizetests. BDiamondslurry:0-0.2m CDiamondslurry:0-0.5m Three-dimensionalshapeofsiliconmirrorchipmicro-poresidewallsurfacesafterabrasivesizetestingasmeasuredbyanopticalprolometer. 56

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Experimentalconditionsforpolishingtimetest. Workpiece Simirrorchip7.50.2mmPoresize101500mAbrasiveslurry Colloidalaluminasuspension0.05m(meandiameter)Suppliedamount:1mLMagneticuid WaterbasedmagneticuidSuppliedamount:1mLPole-Poledistance 15mmMagneticuxdensity 65.5mTAlternatingcurrent 1A,25HzPolishingtime 30,60,120min however,thosedierencesinroughnesscouldbeduetodierencesintheinitialstateofthewafer.Evenwithanindeterminateroughnesstrendunderanelter,itseemsasthough1hourissucienttopolishmicro-poresidewallsasmostofthepolishingseemstobeaccomplishedinthatamountoftime. BAveraginglter Surfaceroughnessresultsfrompolishingtimetests. 4-3 showstheexperimentalconditionsforthisexperiment.Figure 57

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BPolishingtime:60min CPolishingtime:120min Three-dimensionalshapeofsiliconmirrorchipmicro-poresidewallsurfacesafterpolishingtimetestingasmeasuredbyanopticalprolometer. Table4-3. Experimentalconditionsforoscillatingfrequencytest. Workpiece Simirrorchip7.50.2mmPoresize201500mAbrasiveslurry Diamondslurry0.05m(meandiameter)Suppliedamount:1mLMagneticuid WaterbasedmagneticuidSuppliedamount:1mLPole-Poledistance 15mmMagneticuxdensity 65.5mT@25Hz,53.8mT@50HzAlternatingcurrent 1A,25,50HzPolishingtime 60min 4-10 showstheroughnessresultsunderbothcoarseandnelters.Figure 4-11 showsthesurfaceprolerdataforeachpolishedmirrorchipintheformofobliqueplots. Theuid,likeanyphysicalsystem,respondstoanexternalstimuluswhichis,inthiscase,thealternatingmagneticeld.Atlowfrequencies(1-10Hz)theuidexhibitsauni-modalresponse.Athigherfrequencies(over10Hz)theuiddevelopssecondaryand 58

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BAveraginglter Surfaceroughnessresultsfromfrequencyvariationtests. BFrequency:50Hz Three-dimensionalshapeofsiliconmirrorchipmicro-poresidewallsurfacesafterfrequencyvariationtestingasmeasuredbyanopticalprolometer. 4-4 liststheexperimentalconditionsforthisexperiment.Figure 4-12 showstheroughness 59

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Experimentalconditionsformicro-porewidthtest. Workpiece Simirrorchip7.50.2mmPoresize101500,201500,501500mAbrasiveslurry Diamondslurry0.05m(meandiameter)Suppliedamount:1mLMagneticuid WaterbasedmagneticuidSuppliedamount:1mLPole-Poledistance 15mmMagneticuxdensity 65.5mTAlternatingcurrent 1A,25HzPolishingtime 60min resultsunderbothacoarseandanelter.Figure 4-13 showsthesurfaceprolerdataforeachpolishedmirrorchipintheformofobliqueplots. Thereisnotacleartrendinthecoarselteredroughnessvalues.However,thenelteredroughnessvaluesdoshowatrend.Apparently,smallerslitwidthyieldsbettersmallscaleroughness.Thisoccurrencecouldbeduetothefactthatintheexperiment,theuidoscillatedatthesamevelocityforallthreemirrorchips.Whentheuidimpingesonthemirrorchipface,theuidisbothpressuredbyuidmomentumandpulledbymagneticforcethroughthemicro-pores.Themagneticabrasiveuidwouldowfasterthroughthemicro-poresofreducedsizedthanthroughlargermicro-pores.Fasteruidowwouldyieldamoreecientpolishingprocesswithhighernishingforcesandwouldleaveabettersurface. 60

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BAveraginglter Surfaceroughnessresultsfrommicro-porewidthtests. BMicro-porewidth:20m CMicro-porewidth:50m Three-dimensionalshapeofsiliconmirrorchipmicro-poresidewallsurfacesaftermicro-porewidthvariationtestingasmeasuredbyanopticalprolometer. 61

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Experimentalconditionsforchemicalassistancetest. Workpiece Simirrorchip7.50.2mmPoresize201500mAbrasiveslurry ColloidalSilica40-50nmmeandiameterSuppliedamount:1mLMagneticuid WaterbasedmagneticuidSuppliedamount:1mLPole-Poledistance 15mmMagneticuxdensity 65.5mTAlternatingcurrent 1A,25HzPolishingtime 60min isthenattachedtothesubstrateatoms.Mechanicalactionfromapolishingpadremovestheattachedsilicaparticleandthesiliconatomstowhichitwasbonded.Thismechanismofmaterialremovalallowsittobeextremelypreciseasitliterallyremovesasinglelayerofatomsatatime Theeectsonsurfaceroughnessofchemicalassistancewereexamined.Table 4-5 liststheexperimentalconditionsforthisexperiment.Figure 4-14 showstheroughnessresultsunderbothacoarseandanelter.Figure 4-15 showsthesurfaceprolerdataforeachpolishedmirrorchipintheformofobliqueplots. Itisdiculttostateifatrendexistsfromthesetwotrials.Itisalsodiculttostatewhetheranymaterialwasremovedatall.Thesilicaparticlesshouldhaveahardnesssimilartothatofthesiliconmirrorchip.Therefore,ifanymaterialremovaloccurs,itisunlikelythatitisaresultofmechanicalremovalandverylikelythatitwastheresultofchemicalaction.Also,incommercialpolishingapplicationthatusecolloidalsilica,itisonlyusedasanalsteptoreducethesurfaceroughnessofsiliconwafersfromafewnanometerstolessthan1nm;inotherwords,itisusedtoremovesmallwavelengthsurfaceerrorsinthetargetsurface 4-14 ,achangeinsurfaceroughnessisseen;however,sinceCMPisbelievedtoonlyaectsmallwavelengthsurfaceerrors,onemustassumethattheprocesshadnoeectunderthislterandthatthe 62

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BAveraginglter Surfaceroughnessresultsfromchemicalassistancetests. TheneplotofFigure 4-14 showsasmallchangeinroughness.However,thischange(about0.3nmrms)isnotenoughtodeclareastheresultofthepolishingprocessfortworeasons.First,theroughnessat2hoursofpolishingisactuallyhigherthantheroughnessat1hourwhichisanunexpectedandunintuitiveresult.Second,sincethedierenceinroughnessunderthecoarselterofthetwomirrorchipsusedtorunthisexperimentissodrastic(>15nmrms),oneshouldassumethattheroughnessofthetwomirrorchipsundernelterwouldbealsobeincomparable.Theresultsfromthistestarethereforeinconclusiveandrequirefurtherstudy.Unfortunately,duetothelimitednumberofworkpieces,furthertestingwasnotpossible. 4.4.1UnpolishedState 63

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BPolishingtime:120min Three-dimensionalshapeofsiliconmirrorchipmicro-poresidewallsurfacesafterchemicalassistancetestingasmeasuredbyanopticalprolometer. is13nmrms.Also,theoverallshapeofthesidewallsurfacetendstobeveryatwhereasthesidewallsofDRIE-fabricatedmicro-poresoftenhavesomecurvaturethroughoutthethicknessofthemirrorchip.Figure 4-16 showsbothanobliqueplotofthesurfaceofonemicro-poreandanintensitymapofthesamedata.Aperiodictextureisseen. BIntensitymap Opticalprolometerdataforanunpolishedmirrorchip. ThefactthatLIGA-fabricatedmirrorchipsaremadeofnickelismorepromising,asnickelissofterthansilicon;havingasoftersubstratematerialistypicallyadisadvantageinapolishingprocessesasplowingandrubbingoccursmoreoftenattheabrasivecuttingedge-workpieceinterfacethanwithhardermaterials.However,sincethisprocessseemstoapplyminimalforce,thepolishingprocesswasexpectedtoworkmoreeciently. 64

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Experimentalconditionsfornickelmirrorchiptrial. Workpiece Nimirrorchip7.50.2mmPoresize202000mAbrasiveslurry Diamondslurry0-0.5mSuppliedamount:1mLMagneticuid WaterbasedmagneticuidSuppliedamount:1mLPole-Poledistance 15mmMagneticuxdensity 65.5mTAlternatingcurrent 1A,25HzPolishingtime 60min OnlytwoLIGA-fabricatedmirrorchipswereprovided.Afulltestingsequencewasthereforenotpossible.Instead,asingletrialwasexecuted.TheparametersforthistestwerechosenbasedontheresultsfromthetestingdoneonDRIE-fabricatedmirrorchips.Thechosenparameterswereonesthatseemtoyieldthebestresultssuchas1hourpolishingtime,0-0.5mdiamondslurry,25Hzoscillationfrequency. 4-6 liststheexperimentalconditionsforthispolishingtrial.Figure 4-18 showstheroughnessresultsunderbothacoarseandanelter.Figure 4-17 showsthesurfaceprolerdataforthepolishedwaferintheformofanobliqueplotofthesurfaceandanintensitymap. Accordingtothedata,thistestwasundeniablysuccessful.Figure 4-18 showsadenitechangeinroughnessunderbothcoarseandnelters.ThereisclearevidenceofmaterialremovalinintensitymapsofFigures 4-18 and 4-16 .Instep7ofFigure 1-11 ,thenalworkpieceisshowntohaveathingoldplatingonallverticalsurfaces;thisimpliesthatthesurfaceseenintheintensitymapofFigure 4-16 isgold.TheintensitymapofFigure 4-17 showsdarkareasandlightareas;wherethelightareasarepresumedtobemadeofgoldandthedarkerareasarepresumedtobewheretheunderlyingnickelhasbeenexposed.Clearly,morepolishingtimeisrequiredtofullyremovethegoldlayer, 65

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BIntensitymap Opticalprolometerdataforapolishedmirrorchip. BAveraging Comparisonofsidewallsurfaceroughnessbeforeandafterpolishing. 66

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5-1 isaschematicofthetestingsetup.Essentially,acollimatedbeamofx-raysisaimedatthemirrorchip,whosemicro-poresidewallsareinitiallyparallelwiththeincidentbeam.Theincidentangle,inthiscase,istheacuteanglebetweenthex-raysandthemicro-poresidewallsurface.Themirrorchipisslowlyrotateduntilthex-raysareobscured.Theintensityofthereectedx-raysismeasuredbyadetectordirectlybehindthemirrorchip. Figure5-1. Schematicofx-rayreectancetestingsetupformicroporemirrorchips. Figure 5-2 hasaphotographofanouterviewofthetestingdeviceatJAXA.Theinsideofthisdeviceisheldatavacuumduringtestingtominimizetheabsorptionofx-raysintoair.ThelefthalfofFigure 5-2 isaschematicofthetestingdevice.Asshownintheschematic,theleftareaiswherethex-raysaregenerated.Thex-raysarecollimatedbypassingthroughapin-holeopening.Theythentraveldownavacuumpipethroughanotherpin-holeforfurthercollimation.Themirrorchipismountedona2axisgoniometerwhichisthenmountedontoathreeaxisstage(notlabeled).Sincethex-ray 67

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Figure5-2. X-rayreectancetestingsetup. Datafromthetestisthenplotted.Iftherethemirrorchipexhibitednox-rayreection,alineardropinintensityversusincidentanglewillbeobservedduetothemirrorchip'sgeometry.Ifthemirror-chipdidreectx-rays,anexcessinintensityatsmallangles(<2)wouldhavebeenobserved. Figure 5-3 showsthereectiondataforapolishedLIGA-fabricatednickelmirrorchip.InFigure 5-3 ,theexcessinintensityduetox-rayreectionofthesidewallsislabeled;the 68

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Figure5-3. X-rayreectancedataforapolishednickelmirrorchip. 69

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1. Anewnishingprocessforimprovingthesurfaceroughnessofmicro-poresidewallswasconceived,anditsprocessingprinciplewasdenedaccordingtoanassessmentoftheworkpiecedimensionsandpriorsurfaceengineeringknowledge. 2. Amachinewasdevelopedtomaterializetheprocessingprinciple.Foraferrousuidtomaterializetheprocessingprinciple,itmusthavelowmagneticforceandlowviscositysuchthattheuiddynamicmotion,encouragingrelativemotionbetweentheabrasiveparticlesandthemicro-porewallsurface. 3. Thenishingcharacteristicsofthepolishingprocesswerestudiedthroughaseriesofpolishingexperiments.Theeectsonsurfaceroughnessofprocessparameterswerestudied;theseincludedabrasivesize,frequencyofmagneticeldoscillation,polishingtime,andchemicalassistance. 4. Themechanismbywhichmaterialremovaloccurswasdeterminedbyobservationspreliminarytrials.Itwasnoticedthattheprincipalagentdeterminingthesuccessofapolishingtrialwasthemagneticabrasiveuid'sdynamicmotion.Fluidagitation(dynamicmotion)wasfoundtobeprimarilycontrolledbythefrequencyofmagneticeldoscillationandthemagneticeldstrength. 5. X-rayreectiontestsdemonstratedthepolishingprocess'eectivenessinimprovingthex-rayreectivityofmirror-chips. 70

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Thisnewpolishingprocess'feasibilityforfutureapplicationswilldependonbothitsfurtherdevelopmentandintheunderstandingofitsprocessspecictrends.Analytical,empirical,andtheoreticalmodelsmayneedtobeestablished;however,thispolishingprocessis,infact,new,asthereisnootherpolishingprocessinexistencethatemploysthedynamicmotionofanMF-basedmagneticabrasiveuidactuatedbyanalternatingmagneticeldtocausematerialremoval. Tasksrequiredintheimmediatefutureofthisresearchinvolvetherunningofamoreelaborate,thoroughandstatisticallysoundtestingsequencetoverifytheeectsofvaryingprocessparameterswithahigherlevelofcondence.Hopefully,usefultrendswillbedetermined.Alsoanewmachine,capableofpolishingfull-sizemicro-porex-raymirrors,willneedtobedeveloped. Thisnewmachinedesignwillgreatlyimproveonthemachineusedforthisresearch.Onemajorproblemistheoverheatingoftheelectromagnetsallowingthemachinetorunjust1houratatime.Thisproblemshallbeovercomethroughseveralapproaches.Insteadofsolidsteelmagneticcomponents,laminatedsteelshallbeused;thisisacommontechniqueinindustry.Greatercarewillbeusedinthewindingofthecoilsfortheelectromagnets.Also,aclosedloopwatercoolingsystemwillbeimplementedintothenewdesign.Thesemeasuresshouldallowthenewmachinetorunforextendedperiodsoftime(days).Acomputercontrolledmotionandpowercontrolsystemshallbeintegratedinto 71

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Oncethefull-sizemicro-porex-raymirrorsmeetdesignspecications,thetelescope,forwhichtheseopticsareintended,shallbeprototyped.Itishopedthatthedevelopmentofthistelescopewilleventuallyleadtoitbeinglaunchedintospaceforasuccessfulmission. Thisresearchhasexploredanewareaofpolishingtechnology;thiswasachallengingtaskbecausetherewasoftennoreferencebywhichtomakeaneducateddecisions.Often,decisionsweremadebasedsimplyonintuition.Itishopedthatthisworkwillserveasareferencepointforfutureresearchonthistopicandthatuseofthistechnologycanhelprendernewx-raytelescopestostudyobjectsindeepspace,improvingmankind'sknowledgeofphysicsandtheuniverse. 72

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Experimentalconditionsforeachtestonsiliconmirrorchips. TestTestvariableAbrasiveslurryTimehrFrequencyHzPoreorientation 1Time0.05mColloidalAlumina0.525Horizontal2Time0.05mColloidalAlumina125Horizontal3Time0.05mColloidalAlumina225Horizontal4Orientation0.05mDiamondSlurry125Horizontal5Orientation0.05mDiamondSlurry125Vertical6SlitWidth0.05mDiamondSlurry125Horizontal7SlitWidth0.05mDiamondSlurry125Horizontal8SlitWidth0.05mDiamondSlurry125Horizontal9Frequency0.05mDiamondSlurry125Horizontal10Frequency0.05mDiamondSlurry150Horizontal11AbrasiveSize0.05mDiamondSlurry125Horizontal12AbrasiveSize0-0.2mDiamondSlurry125Horizontal13AbrasiveSize0-0.5mDiamondSlurry125Horizontal14CMPTime40-50nmColloidalSilica125Horizontal15CMPTime40-50nmColloidalSilica225Horizontal

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Siliconmirrorchipsusedfortestingandtheirmicro-poredimensions. TestPorewidthmPorespacingmRadiusmm 11030050210300150310300250450100150550100250610501507205015085050250920501501020100501110505012105025013101005014203002501520200250 TableA-3. Surfaceroughnessvaluesofsiliconmirrorchipmicro-poresidewalls LargelterFineFilterTestrmsnmRanmrmsnmRanm 124.34114.0131.671.22329.9716.8442.5051.5310.1177.4941.3631.035414.6310.1963.5982.432516.59310.053.1552.231613.8688.5590.930.682711.7868.4841.8661.433811.3718.992.541.992911.7868.4841.8661.4331014.54510.6823.7482.7311133.50923.41.1560.8721223.36214.1831.441.0261312.1177.4571.2270.9421432.43412.042.061.4481514.21310.4752.4081.868 75

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[1] \X-rayastronomy,"(September2004).http://imagine.gsfc.nasa.gov/docs/science/know l2/history xray.html. [2] Ezoe,Y.,Mitsuisi,I.,Takagi,U.,Ishida,M.,Mitsuda,K.,Yamasaki,N.,Shirata,T.,Ohashi,T.,Fujiwara,K.,Morishita,K.,Nakajima,K.,Fujihira,S.,Kanamori,Y.,Riveros,R.,Yamaguchi,H.,Kato,F.,Sugiyama,S.,andMaeda,R.,\Developmentoflight-weight&high-resolutionx-rayporeopticsinjapan,"InternationalWorkshoponAstronomicalX-rayOptics(December2008). [3] Tipler,P.A.andMosca,G.,[Physicsforscientistandengineers,Volume2],WorthPublishers,NewYork(1995). [4] Spiller,E.,\X-rayoptics,"Advancesinx-rayanalysis42,297{307(2000). [5] Petre,R.,\X-rayimagingsystems,"(September2004).http://imagine.gsfc.nasa.gov/docs/science/how l2/xtelescopes systems.html. [6] \Chandrax-rayobservatory,"(July1999).http://www.shuttlepresskit.com/STS-93/payload45.htm. [7] \Suzaku:Thex-rayrelescope,"(June2005).http://imagine.gsfc.nasa.gov/docs/features/exhibit/astroe2 xray telescope.html. [8] Ezoe,Y.,Koshiishi,M.,Mita,M.,Mitsuda,K.,Hoshino,A.,Ishisaki,Y.,Yang,Z.,Takano,T.,andMaeda,R.,\Microporex-rayopticsusinganisotropicwetetchingof(110)siliconwafers,"AppliedOptics45(35),8932{8938(2006). [9] Marxer,C.,Thio,C.,Gretillat,M.-A.,deRooij,N.F.,Battig,R.,Anthamatten,O.,Valk,B.,,andVogel,P.,\Verticalmirrorsfabricatedbydeepreactiveionetchingforber-opticswitchingapplications,"JournalofMicroelectromechanicalSystems6(3),227{285(1997). [10] Carlo,F.D.,Mancini,D.,Lai,B.,andSong,J.,\Characterizationofexposureandprocessingofthickpmmafordeepx-raylithographyusinghardx-rays,"MicrosystemTechnologies4,86{88(1998). [11] Becker,H.andHeim,U.,\Hotembossingasamethodforthefabricationofpolymerhighaspectratiostructures,"SensorsandActuators83,130{135(2000). [12] Baron,Y.M.,[Technologyofabrasivemachininginamagneticeld],Masino-strojenije,Leningrad,Russia(1975). [13] Yamaguchi,H.,[Handbookoflappingandpolishing],CRCPress,BocaRaton,Florida(2007). [14] Ruben,H.,[AdvancesinSurfaceTreatments],PergamonPress,Oxford(1987). 76

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Shinmura,T.andYamaguchi,H.,\Studyonanewinternalnishingprocessbytheapplicationofmagneticabrasivemachining(internalnishingofstainlesssteeltubeandcleangasbomb),"JSMEInternationalJournal,SeriesC38(4),798{804(1995). [16] Yamaguchi,H.,Yumoto,K.,Shinmura,T.,andOkazaki,T.,\Studyofnishingwafersbymagneticeldassistednishing,"JournalofAdvancedMechanicalDesign,Systems,andManufacturing3(1),35{46(2009). [17] Mahalik,N.,[Micromanufacturingandnanotechnology],Springer,Germany(2006). [18] Svoboda,J.,[Magnetictechniquesforthetreatmentofmaterials],KluwerAcademicPublishers,TheNetherlands(2004). [19] Kordonski,W.andGolini,D.,\Fundamentalsofmagnetorheologicaluidutilizationinhighprecisionnishing,"JournalofIntelligentMaterialSystemsandStruc-tures10,683{689(1999). [20] Kurobe,T.,Imanaka,O.,andTachibana,S.,\Magneticeld-assistednenishing,"BulletinoftheJapanSocietyofPrecisionEngineering17(1),49{50(1983). [21] Yamaguchi,H.,Shinmura,T.,andSekine,M.,\Uniforminternalnishingofsus304stainlesssteelbenttubeusingamagneticabrasivenishingprocess,"ASMEJournalofManufacturingScienceandEngineering127,605{611(2005). [22] Yamaguchi,H.,Shinmura,T.,andIkeda,R.,\Studyofinternalnishingofausteniticstainlesssteelcapillarytubesbymagneticabrasivenishing,"ASMEJournalofManufacturingScienceandEngineering129,885{892(2007). [23] Yamaguchi,H.,Shinmura,T.,andTakenaga,M.,\Developmentofanewprecisioninternalmachiningprocessusinganalternatingmagneticeld,"PrecisionEngineer-ing27,51{58(2003). [24] Nakajima,K.,Fujiwara,K.,Pan,W.,andOkuda,H.,\Shapedsilicon-crystalwafersobtainedbyplasticdeformationandtheirapplicationtosilicon-crystallenses,"NatureMaterials4,47{50(2005). [25] Bennett,J.M.,[LightScatteringandNanoscaleSurfaceRoughness],Springer,NewYork(2007). [26] Doi,T.K.,[HandbookofLappingandPolishing],CRCPress,BocaRaton,Florida(2007). 77

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RaulRiveroswasbornin1985inthecityofMaracay,Venezuela,toIvanandAngelicaRiveros.HeandhisfamilycametotheUnitedStatesin1992,andhehaslivedinFloridaeversince.HejoinedtheUniversityofFloridain2005andgraduatedwithaBachelorofScienceinmechanicalengineeringin2007.Asanundergraduate,RaulconductedresearchattheMachineToolResearchCenter(MTRC).HestartedhisgraduateworkundertheguidanceofDr.HitomiYamaguchiGreensletinJanuaryof2008andgraduatedwithaMasterofScienceinmechanicalengineeringinMay2009fromtheUniversityofFlorida. 78