Optimization of Comb-Drive Actuators

135 Pages·2010·8.56 MB·English

Digitalversion,20thDecember2010.
Graduationcommittee
Prof.dr.ir. TonJ.Mouthaan UniversityofTwente(chairmanandsecretary)
Prof.dr. MikoC.Elwenspoek UniversityofTwente(promotor)
Dr.ir. LeonAbelmann UniversityofTwente(assistantpromotor)
Prof.dr. GaryK.Fedder CarnegieMellonUniversity,Pittsburgh,PA,USA
Prof.dr. PieterH.Hartel UniversityofTwente
Prof.dr.ir. FredvanKeulen DelftUniversityofTechnology,theNetherlands
Prof.dr.ir. GijsJ.M.Krijnen UniversityofTwente
Dr. MarkA.Lantz IBMZu¨richResearchLaboratory,Switzerland
Prof.dr.ir. StefanoStramigioli UniversityofTwente
Paranymphs
WabeW.Koelmans
Le´onA.Woldering
TheresearchpresentedinthisdissertationwascarriedoutattheTransducersScience&
TechnologygroupattheMESA+InstituteforNanotechnologyattheUniversityofTwente,
Enschede,theNetherlands.TheprojectissupportedbytheDutchTechnologyFoundation
STW,whichistheappliedsciencedivisionofNWO,andtheTechnologyProgrammeofthe
MinistryofEconomicAffairs(“A4–Adaptivenon-volatilestorAgesystemsforAdaptive
Applications”,projectnumberTES.06369)
E-mail:[email protected]
Onthecover,amicroniumwafer(front),wheretheinstrument’sresonatorsappearcoloured
becausetheincidentlightisdiffractedbytheperforationoftheresonatormasses;andaport-
raitoftheauthor(back),seenthroughthelithographymaskusedtofabricatethemicronium.
PhotosbyArvidJense.
PrintedbyGildeprintDrukkerijen,Enschede,theNetherlands
Copyright©2010JohanB.C.Engelen,Enschede,theNetherlands
Somerightsreserved.Allorpartofthisbookmaybereproducedortransmittedinanyformorbyany
means,electronicormechanical,includingphotocopying,orbyanyinformationstorageorretrieval
system,withoutpermissioninwritingfromtheauthor,onlyifproperreferencetotheoriginalworkis
made.
ISBN 978-90-365-3120-7
DOI 10.3990/1.9789036531207
Optimization of Comb-Drive Actuators
Nanopositioners for Probe-based Data Storage
and Musical MEMS
dissertation
toobtain
thedegreeofdoctorattheUniversityofTwente,
ontheauthorityoftherectormagnificus,
prof.dr.H.Brinksma,
onaccountofthedecisionofthegraduationcommittee,
tobepubliclydefended
onFriday,14January2011at13:15
by
Johannes Bernardus Charles Engelen
bornon8June1983,
inNijmegen,theNetherlands
Thisdissertationisapprovedby
Prof.dr.MikoC.Elwenspoek UniversityofTwente(promotor)
Dr.ir.LeonAbelmann UniversityofTwente(assistantpromotor)
Theeraofinfinitestorage
Imaginecarryingallthemusiceverrecorded
bythehumanraceinyourpocket.Thatwillbe
possiblebytheendofthisdecade.Ifyouwant
allthemoviesandTVprograms,too,thatwill
takeonlyafewyearsmore.Orimaginemaking
anaudiorecordingofyourwholelife,from
beginningtoend:thatisaffordablealready.
Videowillbepossibleinafewyears.Data
storagedevicessuchasharddrivesandflash
memoryhavegottensodenseandsocheapthat
formostpurposestheirstoragecapacitywill
soonbeunlimited.
Theeraofinfinitestorageisabouttobegin.
Felten,2010
i

Contents
Theeraofinfinitestorage i
Contents iii
1 Introduction 1
1.1 Parallelprobe-baseddatastorage . . . . . . . . . . . . . . . . . . . 2
2 Scannersforprobedatastorage 5
2.1 Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.1 Electromagnetic . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.2 Electrostaticcombdrives . . . . . . . . . . . . . . . . . . . 10
2.2.3 Electrostaticsteppermotors . . . . . . . . . . . . . . . . . 14
2.2.4 Piezoelectric . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.3 Sensorsandcontrol . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3 Amass-balancedelectrostaticx/y-scanner 21
3.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2 Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.3 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.5 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4 Optimizedcomb-drivefingershapeforshock-resistantactuation 31
4.1 Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.1.1 Analyticalmodel . . . . . . . . . . . . . . . . . . . . . . . . 34
4.1.2 Graphicaldeterminationofequilibriumstability . . . . . 36
4.1.3 Designofoptimalshape . . . . . . . . . . . . . . . . . . . . 38
4.1.4 Asymmetricshape . . . . . . . . . . . . . . . . . . . . . . . 40
4.2 Finite-elementanalysis . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.3 Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.3.1 Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.3.2 Measurementresults . . . . . . . . . . . . . . . . . . . . . . 47
iii
4.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.6 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5 Energyconsumptioncomparison 51
5.1 Generalaspects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.2 Comb-driveactuation . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.3 Electrodynamicactuation. . . . . . . . . . . . . . . . . . . . . . . . 56
5.4 Seektimecalculations . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.4.1 Combdriveswith‘optim’fingers . . . . . . . . . . . . . . . 59
5.4.2 Electrodynamicactuator . . . . . . . . . . . . . . . . . . . 59
5.5 Energycostcalculations . . . . . . . . . . . . . . . . . . . . . . . . 60
5.5.1 Stayenergy . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5.5.2 Read/writeenergy . . . . . . . . . . . . . . . . . . . . . . . 61
5.5.3 Seekenergy . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5.6 Resultsforhypotheticaldesigns . . . . . . . . . . . . . . . . . . . . 65
5.6.1 Seektime . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.6.2 Stayenergy . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.6.3 Read/writeenergy . . . . . . . . . . . . . . . . . . . . . . . 68
5.6.4 Seekenergy . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5.7 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5.8 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
6 TheMicronium—amusicalMEMSinstrument 73
6.1 Theoryanddesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
6.1.1 Resonatortheory . . . . . . . . . . . . . . . . . . . . . . . . 74
6.1.2 Instrumentdesign . . . . . . . . . . . . . . . . . . . . . . . 75
6.1.3 Capacitiveread-out . . . . . . . . . . . . . . . . . . . . . . 76
6.1.4 Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.2 Experimentaldetailsandresults . . . . . . . . . . . . . . . . . . . . 79
6.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.5 TheMicroniumproject . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.6 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
7 Conclusionandfutureoutlook 89
Appendices 93
A Optimalchargingofacapacitor 95
A.1 Withoutleakageresistor . . . . . . . . . . . . . . . . . . . . . . . . 95
A.2 Withleakageresistor . . . . . . . . . . . . . . . . . . . . . . . . . . 95
B Seektimeforelectrodynamicactuator 99
C ProcessFlow 103
iv
Bibliography 108
Summary 118
Samenvatting 119
Publications 120
Dankwoord 122
Biography/Biografie 124
v