Mechanical Engineering/Bioengineering/Electrical Engineering/Materials Science/Manufacturing Engineering Third Edition Fundamentals of MICROFABRICATION NANOTECHNOLOGY AND M M V O LU M E I I i a c Manufacturing Techniques for Microfabrication and Nanotechnology n r o u Focuses on Emerging Trends and Traditional Manufacturing Methods f f r a a c Designed for science and engineering students, Manufacturing Techniques for Microfabrication and b t Nanotechnology focuses on emerging trends in processes for fabricating MEMS and NEMS devices. u r The book reviews different forms of lithography, subtractive material removal processes, and additive i r technologies, detailing those that differ the most from the miniaturization processes used to fashion ICs. It c i exhaustively covers top-down and bottom-up fabrication processes and compares the merits of the different a n approaches. Fully illustrated in color, the text contains end-of-chapter problems, worked examples, extensive t g i references for further reading, and an extensive glossary of terms. o T n Topics include: e c • Alternative next-generation lithographies (NGEs), including extreme ultraviolet (EUV), x-ray, a h n and charged particle lithographies n • Lithography techniques in the early research and development stage, such as very thin resist layers d i and block copolymers, zone plate array lithography, quantum lithography, and proximal probe- q N based techniques u • Gas and vapor dry etching processes, including chemical, physical, and chemical-physical a e • Wet chemical etching, wet bulk micromachining, thermal removing techniques, and traditional n s and nontraditional mechanical removing techniques o f • Recent developments to miniaturized mechanical manufacturing equipment, the so-called t o e desktop factories r • Additive (forming) processes, physical vapor deposition processes, chemical vapor deposition c h micromachining, thin film properties, and surface micromachining n • Additive chemical, photochemical, and electrochemical processes geared towards BioMEMS o applications, thermal forming techniques, and plastic molding techniques l o The second volume in Fundamentals of Microfabrication and Nanotechnology, Third Edition, Three-Volume g Set, the book provides a guide for establishing the appropriate fabrication technique for any type of micro- y or nanomachine. Other volumes in Fundamentals of Microfabrication and Nanotechnology, Third Edition, Three-Volume Set include: Solid-State Physics, Fluidics, and Analytical Techniques in Micro- and Nanotechnology From MEMS to Bio-MEMS and Bio-NEMS: Manufacturing Techniques and Applications VOLUME II 55194 Madou ISBN: 978-1-4200-5519-1 90000 9 781420 055191 55194_COVER_final.indd 1 5/5/11 10:13 AM Marc J. Madou Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2011 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20110720 International Standard Book Number-13: 978-1-4398-9530-6 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. 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Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com I dedicate this third edition of Fundamentals of Microfabrication to my family in the US and in Belgium and to all MEMS and NEMS colleagues in labs in the US, Canada, India, Korea, Mexico, Malaysia, Switzerland, Sweden and Denmark that I have the pleasure to work with. The opportunity to carry out international research in MEMS and NEMS and writing a textbook about it has been rewarding in terms of research productivity but perhaps even more in cultural enrichment. Scientists have always been at the frontier of globalization because science is the biggest gift one country can give to another and perhaps the best road to a more peaceful world. Contents Roadmap ix Author xi Acknowledgments xiii Part I Lithography IntroductiontoPartI 2 1 Photolithography 3 2 Next-GenerationLithographiesandLithographyResearch 89 Part II Pattern transfer with Subtractive techniques IntroductiontoPartII 148 3 DryEtching 155 4 WetChemicalEtchingandWetBulkMicromachining—PoolsasTools 215 5 ThermalEnergy-BasedRemoving 319 6 MechanicalEnergy-BasedRemoving 351 Part III Pattern transfer with additive techniques IntroductiontoPartIII 386 7 PhysicalandChemicalVaporDeposition—ThinFilmPropertiesandSurfaceMicromachining 391 8 Chemical,Photochemical,andElectrochemicalFormingTechniques 509 vii viii      Contents 9 ThermalEnergy-BasedFormingTechniques—Thermoforming 567 10 MicromoldingTechniques—LIGA 591 Roadmap Manufacturing Techniques for Microfabrication and Nanotechnology consistsofthreepartsandtenchapters. InPartI,wereviewdifferentformsoflithography,detailingthosethatdiffermostfromtheminiaturiza- tionprocessesusedtofashionintegratedcircuits(ICs).Chapter1startswithashorthistoricalnoteabout theoriginsoflithography,followedbyadescriptionofphotolithography,includingdevelopmentsthathave allowedtheprintingoftheever-shrinkingfeaturesofmodernICs.Afterreviewingthelimitsofphotolithog- raphy,wedetailalternativenext-generationlithographies(NGEs)inChapter2,includingextremeultraviolet (EUV),x-ray,andcharged-particle(electronandion)lithographies,followedbylithographytechniquesin theearlyresearchanddevelopment(R&D)stage.LithographyapproachesintheR&Dstageincludeverythin resistlayersandblockcopolymers,zoneplatearraylithography(ZPAL),quantumlithography(two-photon lithography),andproximalprobe-basedtechniquessuchasatomicforcemicroscopy(AFM),scanningtun- nelingmicroscopy(STM),dip-penlithography(DPL),near-fieldscanningopticalmicroscopy(NSOM),and aperturelessnear-fieldscanningopticalmicroscopy(ANSOM).Alsoconsideredareholographiclithography, plasmoniclithography,andlithographywithsuperlenses(“Pendry’sdream”).Asanexampleofalithography methodthatiscapableofpatterningresistonnonplanarsubstrates(e.g.,patterningaresistonthesurfaceof acylinder)wedetailsoftlithography. InPartIIwedealwithmaterialremovalprocesses,andadditivetechnologiesarethefocusofPartIII.We reviewgasandvaporphasedryetchingprocesses,includingchemical,physical(purelymechanical),and chemical-physical(mostlychemicalwithsomemechanicalassist)inChapter3.Chapter4consistsoftwo parts:onecoverswetchemical etching andtheotherwet bulk micromachining,thelatterbeingchemicaletching aswellbutoptimizedforthemanufactureofICs,nano-,andmicromachines.Chapter5discussesthermal removingtechniqueswherethermalenergy,providedbyaheatsource,meltsand/orvaporizesmaterialfrom theworkpiece.Examplesofthermaltechniquescoveredinthischapterareelectricdischargemachining (EDM)(includingµ-EDM),laser-andelectron-beammachining(LBMandEBM),andplasmaarccutting.In Chapter6,wecovertraditionalandnontraditionalmechanicalremovingtechniques.Traditionalmechanical materialremovingtechnologiescoveredaremechanicalprecisionmachiningandabrasivewheelmachining. Innontraditionalmechanicalmachining,wedealwithultrasonicdrilling,electrolyticin-processdressing (ELID)grinding,waterjet,abrasivewaterjet,abrasivejetmachining,andfocusedion-beammilling(FIB). Alsointhischapter,wehighlightrecentdevelopmentstowardminiaturizedmechanicalmanufacturing equipment,theso-calleddesktopfactories. InPartIIIwecoveradditive(forming)processes,wherematerialsareadded,usuallyinaselectiveman- ner,toaworkpieceoradeviceunderconstruction.Physicalvapordepositionprocesses(PVD)andchemical vapordeposition(CVD)aretopicsofChapter7.Inthesamechapterwesurveythinfilmpropertiesanddetail surfacemicromachining,animportantapplicationofthinfilmdepositiontechniques.Insurfacemicroma- chining,featuresarebuiltup,layerbylayer,onthesurfaceofasubstrate(e.g.,asingle-crystalsiliconwafer). Dryetchingdefinesthesurfacefeaturesinthex,y-plane,andwetetchingreleasesthemfromtheplaneby undercutting.Insurfacemicromachining,shapesinthex,y-planeareunrestrictedbythecrystallographyof thesubstrate.InChapter8wediscussadditivechemical,photochemical,andelectrochemicalprocesses. ThechemicalformingmethodscoveredinChapter8aregearedtowardBioMEMSapplications.Inpho- tochemicalforming,photoenergysolidifiesamaterialintoa3Dshape,asillustratedinrapidprototyping andmicrophotoforming(stereolithography).Inthecaseofelectrochemicalforming,theenergyatthework pieceiselectrochemical.Chapter9coversthermalformingtechniqueswherethermalenergyprovidedbya ix