Resistive switching in Cu: TCNQ thin films [Elektronische Ressource] / vorgelegt von Thorsten Kever

Thorsten Kever

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2009
• Nombre de lectures: 43
• Langue: Deutsch
• Poids de l'ouvrage: 5 Mo

Extrait

ResistiveSwitchinginCu:TCNQ
ThinFilms
VonderFakultätfürElektrotechnikundInformationstechnikder
Rheinisch-WestfälischenTechnischenHochschuleAachenzur
ErlangungdesakademischenGradeseinesDoktorsder
IngenieurwissenschaftengenehmigteDissertation
vorgelegtvon
Diplom-IngenieurElektrotechnik
ThorstenKever
ausErkelenz
Berichter: Univ.-Prof. Dr.-Ing. RainerWaser
JuniorprofessorDr. rer. nat. DirkUweSauer
TagdermündlichenPrüfung: 30.01.2009
DieseDissertationistaufdenInternetseitenderHochschulbibliothekonlineverfügbar.Preface
ThisthesiswaswrittenduringmyPh.D.studiesattheInstitutfürWerkstoffeder
ElektrotechnikoftheRheinisch-WestfälischeTechnischeHochschule(RWTH)Aachen,
Germany.
IwouldliketoexpressmygratitudetoProf. Waserforgivingmetheopportunityto
doresearchintheexcitingfieldofresistiveswitchingmemoriesandforprovidingan
excellentworkingandlearningenvironment.
IamalsoindebtedtoProf. Sauerwhokindlyagreedtobetheco-examinerinthe
jury.
Manythanksalsoto: Dr. Böttgerforhissupportandstimulatingdiscussions;Eike
Linn and Ann-Christin Dippel for fruitfull discussions, carefull proof-reading and
being great office mates; Bart Klopstra, Christian Nauenheim, Carsten Giesen and
TorstenJaspertfortheirdedicatedworkduringtheirdiplomathesis;GiselaWassefor
takingSEMpictures;ChristinaSchindlerforfruitfulldiscussionsandthepreparation
ofcomparisonsamples.
Lastbutnotleast,IwouldliketothankallcolleaguesandallstudentsattheInstitut
fürWerkstoffederElektrotechnikoftheRheinisch-WestfälischeTechnischeHochschule
(RWTH) Aachen and at the Research Center Jülich for their valueable support and
manymemorablemomentsspenttogether.v
Contents
1 Introduction 1
1.1 Motivation...........................................................1
1.2 Stateoftheart........................................................2
1.3 Objectives............................................................3
2 Non–VolatileMemory 7
2.1 Overview............................................................7
2.1.1 ElectricallyAddressedSolid–StateMemorySystems ........... 8
2.2 ConceptsBasedonMetal–Insulator–MetalSetups ................... 16
2.2.1 SwitchingMechanismsinMIMStructures .................... 19
2.2.2 MIMStructuresBasedonOrganicMaterials...................21
2.3 TheChargeTransferComplexCu:TCNQ............................23
2.3.1 TheOrganicLigandTCNQ...................................24
2.3.2 FormationofCu:TCNQ.......................................25
2.3.3 ConductivityofandCTcomplexesinGeneral......28
2.3.4 ResistiveSwitchinginCu:TCNQ..............................29
3 DevicePreparation 33
3.1 ChoiceoftheDepositionMethod....................................33
3.1.1 BasicPrinciplesofVacuumEvaporation ...................... 34
3.2 DesignandConstructionoftheChamber...............36
3.2.1 SetupoftheVacuumChamber................................37
3.2.2 GenerationoftheVacuumPressure...........................37
3.2.3 ToolingoftheEvaporationChamber..........................42
3.2.4 ControlandRegulationoftheSystem.........................45
3.3 DevelopmentoftheDepositionProcesses ........................... 48
3.3.1 SuccessiveEvaporationRoute ................................ 50
3.3.2 TheAnnealingProcess........................................53
3.3.3 SimultaneousEvaporationRoute ............................. 57
3.3.4 DeviceSetup ................................................. 62
3.4 Summary...........................................................68
4 Characterization 69
4.1 PhysicalCharacterization ........................................... 69
4.1.1 UV–VisSpectroscopy.........................................69
4.1.2 IRSpectroscopy...............................................71
4.1.3 XRDMeasurements .......................................... 72vi Contents
4.2 ElectricalCharacterization...........................................74
4.2.1 QuasiStaticCurrent–VoltageMeasurements..................74
4.2.2 ImpedanceSpectroscopy......................................82
4.2.3 PulseMeasurements..........................................85
4.2.4 TemperatureDependence.....................................92
4.3 Summary...........................................................94
5 SwitchingMechanisms 97
5.1 UseofDifferentElectrodeMaterials.................................98
5.1.1 DeviceswithAlTopElectrodes...............................99
5.1.2withPtTopElectrodes .............................. 100
5.1.3 EquivalentCircuits..........................................102
5.1.4 TOF–SIMSMeasurements...................................106
5.2 ControlExperiments...............................................108
5.3 Summary..........................................................109
6 Conclusions 111
6.1 Summary..........................................................111
6.2 Outlook............................................................113
Appendices 115vii
Used Symbols and Abbreviations
δ ............... DegreeofChargeTransfer
C .............. ElectricalCapacitance
E .............. ElectricalField
P .............. Polarization
Q .............. ElectricalCharge
R ..............Resistance
V .............. Voltage
BNC ........... BayonetteNeilConcelman
CMOS ......... ComplemantaryMetalOxideSemiconductor
CSD ........... ChemicalSolutionDeposition
CT ............. ChargeTransfer
DRAM ......... DynamicRandomAccessMemory
EPROM ........ ErasableProgrammableRead–OnlyMemory
FeFET .......... FerroelectricFieldEffectTransistor
FeRAM ........ FerrRandomAccessMemory
FET ............ FieldEffectTransistor
FTIR ........... FourierTransformInfraRed
HV ............ HighVacuum
ICT ............ InformationandCommunicationTechnology
IMT ............ Insulator–MetalTransition
IR .............. InfraRed
ITRS ........... TheInternationalTechnologyRoadmapforSemiconductors
MIM ........... Metal–Insulator–Metal
MIM ........... Metal–I–Metal
MOS ........... MetalOxideSemiconductor
MRAM ........ MagnetoresistiveRandomAccessMemory
MV ............ ManipulatedVariable
NAND ......... NotAND
NFGM ......... Nano–FloatingGateMemory
NMOS ......... n–typeMOS
NOR ........... NotOR
NP ............. NanoParticles
NVM .......... Non–VolatileMemory
NVRAM ....... NonVRandomAccessMemory
PC ............. PersonalComputer
PCM ........... PhaseChangeMemory
PID ............ ProportionalIntegralDerivative
PMC ........... ProgrammableMetallizationCellviii Contents
PV ............. ProcessVariable
PVD ........... PhysicalVaporDeposition
QCM .......... QuartzCrystalMicrobalance
RAM .......... RandomAccessMemory
RIE ............ ReactiveIonEtching
RRAM ......... ResistiveRandomAccessMemory
SEM ........... ScanningElectronMicroscope
SIMS ........... SecondaryIonMassSpectrometry
SOI ............ SiliconOnInsulator
SONOS ........ SemiconductorOxideNitrideOxideSemiconductor
SRAM ......... StaticRandomAccessMemory
STM ........... ScanningTunnelingMicroscope
TCNQ ......... Tetracyanoquinodimethane
TOF ............ TimeOfFlight
UHV ........... UltraHighVacuum
UV–Vis ........ UltraViolet–Visible
VARIOT ....... VariableOxideThicknessfloatinggatememory
XRD ........... X–RayDiffraction
Z–RAM ........ ZeroCapacitanceRandomAccessMemory1
1 Introduction
1.1 Motivation
Thedemandforinformationstoragehasincreasedrapidlyinrecentyears. Newapplica-
tionsandconceptsintheinformationandcommunicationtechnology(ICT),likehigh–
definitionvideo,on–demandTV,multimediaentertainment,anddata/information
services are entering the consumer market every year. Most, if not all of these new
applications,requirethehandlingandstorageoflargeamountsofdata. Therefore,the
marketwillexpectthesemiconductorindustrytomaintaintheexponentialgrowths
predictedbyMoore´slaw[1]forthenextseveralyearsbysuccessfullycontinuingthe
scalingofCMOSbeyondthe22nmgeneration[2].
The focus of ICT products has shifted toward portable and hand held devices in
recentyears. Smallportablesystemsenablecommunication,webbrowsing,imageand
videocapturing,anddata/informationservicesaswellasmultimediaentertainment
fromanyplaceandatanytime. Theexpectedfurtherevolutionoftheseapplicationand
servicesindicateaneverincreasingneedforlargercapacityofdatastoragememories
up to even the Terabyte range. The strong gain in importance of portable devices
emphasis some key parameters of the different technologies stronger than others.
Obviouslysizemattersforhandhelddevicesaswellasrobustnessagainstmechanical
stress. Therefore,massstoragetechnologiesbasedonsolid–statememorysystemsare
stronglyfavored,evenwhentakinghighercostsintermsofpurecost/bitcomparedto
harddiskmassstoragedevicesintoaccount[3].
Consideringtheportablecharacteroftheapplications,energyefficiency(dictatedby
limitedbatterycapacity)isanotherkeyparameterwhileassessingdifferenttechnolo-
gies. Non–volatilememory(NVM)meetstherequirementforlow(zero)powerstorage.
Onlythegrowingdemandofportableconsumerproductslikemobilephones,digital
camera´s,andMP3playersinrecentyears,renderedthetremendoussuccessstoryof
Flashmemoriesonagrandscalepossible. FlashtechnologyisbasedonaMOSFET
transistorwithafloatinggatewherechargescanbestoredinordertomodulatethe
thresholdvoltage[4]. TheNVRAMmarkettodayisdominatedbyN