3D Chip Stacks Novel Thermal Interface Materials
duNovel Thermal InterfaceMaterials for 3D Chip StacksSrilakshmi Lingamnenisril@stanford.eduAdvisor: Prof. Ken GoodsonDepartment of Mechanical Engineering, StanfordIEEE SFBA Nanotechnology Council TalkOct 16, 2012IEEE SFBA Nanotechnology Council
Outline Stanford Nano Heat Lab– Overview of Metrology and Materials Materials for Thermal Management––––3D chip attachments and conductive underfillsHigh density aligned CNT compositesAligned CNT nanotapeMechanical CharacterizationIEEE SFBA Nanotechnology Council2
Thermal and Mechanical CharacterizationCross-sectional IR MicroscopyPico/Nanosecond Thermoreflectance40CNTCNT Film500 μmTemperature (C)35Metal30CNT Film dT kdT 1 dx dxk T RB20growthsubstrateCNT CatalystMetalTransparentSubstrate25150200400 1600TR SignalHeating PulseReflected SignalHeaterTimeDistance (μm)(um)DistanceElectrothermal Characterization3
Thermal and Mechanical CharacterizationCross-sectional IR MicroscopyNanosecond Transient Thermoreflectance40HeaterCNTR”topCNT Film500 μmTemperature (C)35Metal30Film25 dT kdT 1 dx dxk T RB20growthsubstrate150200400 1SiR”filmCv, filmR”base600Distance (μm)(um)DistanceElectrothermal CharacterizationMechanical CharacterizationMicroresonators (In-Plane)Laser DopplerVibrometer(LDV)Nanoindentation (Out-of-Plane)PhotodetectorLaserBeamCNT Film4
MetrologyRig ComplexityPump-probe opticsMulti-propertyMeasurementsSAMPLE FILMKaeding, Skurk, Goodson,Applied Physics Letters (1993)Hybrid Optical-ElectricalMethodsSample ComplexityIEEE SFBA Nanotechnology Council5
Nanodevices and MaterialsData StorageNumonyx/IntelCMOS LasersVuckovic et al., StanfordThermoelectricsSolar ElectrodesThermal InterfacesC. Xi, C-M HsuCui group, StanfordR. Noriega and S. PhadkeSalleo group, StanfordGoodson group, StanfordIEEE SFBA Nanotechnology Council6
Interface PhysicsZijian Li, Elah Bozorg-Grayeli, Jungwan Cho, Si TanExtreme UVNanoOpticsMo/Si MultilayerStructureNovel CompositeSubstrates forPower Electronicsand PhotonicsGaN-diamond compositefor power HEMTs(courtesy Group4 Labs)IEEE SFBA Nanotechnology CouncilPhonon & ElectronNonequilibrium atInterfacesEngineered multilayerinterface for reducing thermalconductance in phase changememory devicesPhysical mechanismsgoverning electron andphonon transport atinterfaces7
Groups of H.S. Philip Wong (EE) andKenneth E. Goodson (ME)Phase Change MemoryIntel (D. Kau, K-W. Chang, Ilya V Karpov, G. Spandini)Sponsors &NXP (F. Hurckx), Micron (John Smythe), IBM (Raoux, Krebs, et al.)Collaborators:National Science Foundation (NSF),Semiconductor Research Corporation (SRC)Thermal CharacterizationCW RadiationforThermometryNanosecond Heatingfrom Nd:YAGToDetectorNovel Geometries, Synthesis, & MultibitMetal coatingJaeho LeeSampleGST film (CNT Array)Zijian LiHeat sink (silicon or metal substrate)Elah Bozorg-GrayeliSangBum KimCrystalline AmorphousJohn ReifenbergYuan ZhangRakesh GnanaSangbum KimJohn ReifenbergThermoElectric Effect (Seebeck)Jaeho Lee,Rakesh Gnana,Zijian LiVCurrent (A)GNDWPCMWThreshold Switching PhenomenaMetal heaterSiO2Electrothermal/Crystallization ModelingPCJohn ReifenbergZijian LeeMicroThermal Stage (MTS)SangBum KimRakesh Gnana,John Reifenberg,Jaeho Lee,Zijian Li8
Key Challenges for TEs in Combustion SystemsImprovements in the intrinsic ZT of TE materials are proving to be very difficult totranslate into efficient, reliable power recovery systems.Major needs include Low resistance interfaces that arestable under thermal cycling.600 CHeatcontact resistancehot side / heat exchanger High-temperature TE materials thatare stable and promise low-costscaleup. Characterization methods thatinclude interfaces and correlate betterwith system performance.thermalthermalinsulation / e.g. ceramic plateconductor/ e.g. copperelectrical& thermalnconductor/ e.g. copperpdiffusion barrierjoining technologyconductor/ e.g. copperinsulation / e.g. ceramic plateelectrical& thermalthermalthermalcold side / heat exchangerCoolingIEEE SFBA Nanotechnology Council90 C9
Automotive Waste Heat RecoveryThermoelectric Modules and Electro-Thermo InterfacesMichael Barako, Lewis Hom, Saniya Leblanc, Yuan Gao, WoosunngPark, Amir Aminfar, Amy Marconnet, Dr. Mehdi AsheghiSolder BondingHigh Temperature IR ImagingIR CameraHot SideCold SideThermal Cycling of TE Modules250 WFigure of MeritAfter 45,000 CyclesFractureZT0.60.55TE Material0.550 μmIEEE SFBA Nanotechnology Council100101102103Cycles10410105 400 oC drop across TE module10
Thermal Management Challenges for MicroprocessorsImportance of Hotspot ThermalManagement Peak temperatures limit the reliability of interconnects Thermo-mechanical strains due to temperature nonuniformities can degrade packaging and interfacesChallenges Ahead for Thermal Management Transistor scaling Increasing number of cores 3D integration Constraints of mobile applicationsAdapted from: http://en.wikipedia.org/wiki/Heat sinkIEEE SFBA Nanotechnology CouncilImages of Electromigration FailureRalph Group, Cornell UniversitySolder joint failure due to thermomechanical stressRidgetop Group Inc.,11
Hot Spot Detection and Thermal ManagementTo resolve transient chip hotspots with increased accuracy and cool themMilnes David, Joe Miler, Lewis Hom, Dr. Mehdi Asheghiwith high-heat flux cooling solutionsThrough-Wafer Hotspot Imaging(a)To detectorRapid Hotspot Prediction & Power Distribution(a)(b)(c)Imaging lensIR radiationPower mapIR tranIR transparewindownt fluidNonunifgene orm hearating chip tDistributedTemperatureSensor NetworkReproducedpower mapVapor-Venting Microfluidic Heat ExchangersFlow 2 ml/min, Mass Flux 103 kg/s-m225/ PΔPtot P 0David et al.,IEEE SFBA Nanotechnology Council10203040506070Heat Flux [W/cm ] 2Heat Flux [W/cm ]212
duThermal Interface materials
3D chips: Material RequirementsGoal: Discover and characterize advanced materials containing nanoscale inclusions(particles, platelets, tubes), targeting the unique property needs of packaging applicationsincluding TSV, interposer, and 3DTIM 1 &2 (metal alloys, particlefilled organics, aligned CNT films)- High thermal conductivity- Mechanical compliance3D Chip Attachment (Adhesives,Thermal compression bonding)- High thermal conductivity- Electrically insulating- Thermal cycling stabilityLogicDRAMDRAMlnterposerChip CarrierMemoryMemoryLogicChip CarrierEncapsulation- High thermal conductivity- Electrically insulating (on theside facing the chip)- Mechanical complianceIEEE SFBA Nanotechnology CouncilFlowable Underfill- Electrically insulating- Mechanical stiffness- Viscosity and capillary forces- High thermal conductivity14
Thermal Interface MaterialsAlN-(xGNP) Exfoliated Graphenenanoplatelet compositesAlN – 10 µm2 μmAligned CNT CompositesxGNPs – 5-15 nm 1 μmNanotape to Replace Solder PadsIEEE SFBA Nanotechnology Council2 mmThermal and Mechanical Characterization15
Thermal Conductivity Measurement – IR strate 2.50QuartzSAMPLE 3.75QuartzHeater 5.00656055[mm]454035Temperature [C]50302520Metal Layer156.251.252.503.755.006.25[mm]Calibration & Verification Emitter tape defines measurement location and uniformemissivity Emissivity calibrated(@ 65-75 oC) using thermocouples Verification performed on known materials Dual heat flux measurement region quantify heat lossesIEEE SFBA Nanotechnology Council16
Aligned CNT Nanocomposites1 vol.% CNT filmBiaxial compression toincrease volume fractionAxialRemove 1 vol.% CNT filmfrom growth substrateInfiltrate with epoxy(RTM-6)1 vol.% CNT CompositeTransverse1 mmIEEE SFBA Nanotechnology CouncilMarconnet et al, ACS Nano (2011)2 mm17
15.05.0Composites - AxialComposites - TransverseUnfilled Arrays - Axial4.0Effective medium approachPower %5%10%Volume Fraction15%Thermal Conductivity [W/m/K]Thermal Conductivity Enhancement][k/kThermal Conductivity of Aligned CNT Nanocomposites0.020%(Surfaces polished to 3nm roughness and coated with 200 nm of Pt to ensure nearly identical contact conditions for all samples andimproves contact between composite and reference layers) Non-linear increase at higher volume fraction suggests that CNT-CNT and CNT-polymer interactions areimportant to the thermal transportCNT’s contribute at a rate of about 10 W/m/K per CNT at low volume fractions, much lower thanexpected.IEEE SFBA Nanotechnology Council18
Aligned CNT NanocompositesAxial ConductionHeat SourceComposite ation inCNT HeightsSpatially Varying AlignmentCNT-CNT ContactsVoidsDefectsIndividual CNT ThermalConductanceHeat SinkCNT-CNT ContactsIndividual CNT ThermalConductanceIEEE SFBA Nanotechnology CouncilHeat SinkComposite InterfaceResistanceHeat SourceTransverse ConductionCNT-EpoxyBoundaryResistanceSpatially Varying AlignmentHeat Sink19
Nanotape to Replace Solder PadsSRC Patent: Hu, Jiang, Goodson, US Patent 7,504,453,issued 2009SRC Patent: Panzer, Goodson, et al., 2009/0068387(pending)Panzer, Maruyama, Goodson et al., Nanoletters (2010)Hu, Fisher, Goodson et al., J. Heat Transfer (2006)Adhesion layerLow melting temperaturebinder (e.g. alloys of Ga, In,Sn)NanofibersRemovablemechanicalbackerIEEE SFBA Nanotechnology CouncilAdhesion layer wets nanotubes andpromotes adhesion of binder (Pd, Pt, or Ti). 100 nm is thetypical variation inCNT height.Upon heating, the low melting binderconforms to CNT and substrate topography.20
Bonded CNT Thermal PropertiesNanofoilBondIndiumBondSiCNT FilmCNTCr/Ni/AuCr/Ni/AuBonding Layer1 μmBondingLayerCr/Ni/Au1 μmFused SilicaTemperature Profile100For constant q'', the interfacial temperaturedrop is reduced by an order of magnitudethrough solder bondingTemperature [C]CNTNFGlass8060402000.511.5Distance [mm]IEEE SFBA Nanotechnology CouncilBarako et al, ITHERM 201221
Bonded CNT Thermal Properties2CNT Bulk Thermal ConductivitykCNT[W/m/K]k [W/m/K] Intrinsic Thermal Conductivityincreases due to improvedengagement of CNTs Thermal boundary resistancedecreases significantly1.51No BondingIndium BondingNanofoil Bonding0.50Barako et al, ITHERM 2012Indium Bonding410UnbondedBonded103R''CNT-In-Glass 28-71 K-mm2/W101010210200400600Axial Pressure [kPa]Nanofoil Bonding800Pressure [kPa][K-mm2/W] 2R '' TBRCNT-NF-Glass [K-mm /W]R '' CNT-In-Glass[K-mm2/W]TBR [K-mm2/W]1003UnbondedBondedR''CNT-NF-Glass 15-50 60022
Thermal Interface MaterialsElastic Modulus (MPa)GOAL: Thermal Conductivity Mechanical FlexibilityImplication: Higher package form NT Data1102Thermo-mechanical Stresses in TEsPhaseChangeMaterialsNanogelsCourtesy of Dr. Boris Kozinsky (Bosch)Greases &Gels101GOAL0.011.00.1Thermal Resistivity (m K / W)1IEEE SFBA Nanotechnology CouncilGao, Goodson, et al., J. Electronic Materials (2010).Won, Goodson, et al., Carbon, submitted (2011).23
Mechanical Properties of CNT FilmsNew Technique: Mechanical ResonatorsThermal and Mechanical CharacterizationResonator lengthand shape variationExperimental SetupCNT on a Cantilever LDV (laser Doppler velocimetry) experimental setup :resonant frequency of various thickness films. Resonant frequency shift : mechanical modulus Ring-down and fitting measurements : quality factorsIEEE SFBA Nanotechnology Council24
Experimental Method and Data InterpretationEuler-Bernoulli differential equation for multi-layer beam 4w i Ai EI Ei I i A 2 EI 4 0 A iidt xPolysilicon deposition 2wResonator outline etchingTransformed section method wnE SiISi E cnt Icnt wn,o Si ASi cnt AcntECNTE si I CNT Si ASiE SiISi,o 1 w 2 A 1 CNT CNT 1 n I I Si, 0 Si Si ASi wn, Si, 0 Resonator etchingOxide layer removalSi-CNT Cantilever Catalyst depositionCarbonnanotubethickness, tcntCarbon Nanotube GrowthBeam thickness, tSiBeam Length, L(200-1000 um)Beam Width, b (25100 um)IEEE SFBA Nanotechnology CouncilWon et al, Carbon (2011)25
Mechanical Behavior of CNT FilmsThickness: 0.5 - 220 µmModulus : 1 - 370 MPaDensity : 25 - 140 kg/m3MWCNTs(Monano)IEEE SFBA Nanotechnology CouncilSWCNTs(U. of Tokyo)MWCNTs(MIT)26
Mechanical Behavior of Nonhomogeneous CNT FilmsThree-layerAnalysisGrowth StagesStage 1Stage 2crustTwo-layer analysis Three-layer analysisE SiISi,1 E MiddleIMiddle ETopITop wn wn,Si,0 Si ASi MiddleAMiddle Top ATop Si ASiE SiISi,0 1: Moduli are scaled by reference sampleDimensionlessand volume fractionEffective ModulusmiddleSelf-organization Vertical-growthcrustSWCNTs (U. of Tokyo)Theoretical curve forMWCNT filmsMWCNTs (Monano)MWCNTs (MIT)middle Interweaving of a thin layer ofentangled and randomly orientednanotubes Vertical-aligned growth Density decayIEEE SFBA Nanotechnology CouncilSWCNT films27
Conclusions - Materials for Thermal Management– Development of novel thermal interface materials iscrucial for 3D circuits performance– Nano tape is a promising replacement to solder pads– Measurements of aligned CNT films and compositesshowed thermal conductivity and elastic moduluscomparable to or better than commercial TIMs– Thermal conductivity data of AlN-xGNP nanocompositesshowed promising trends and are potential candidates forunderfill materialsIEEE SFBA Nanotechnology Council28
Contact Info: Srilakshmi Lingamneni (sril@stanford.edu)Prof. Ken Goodson /
(b) Distributed Temperature Sensor Network (c) Reproduced power map (a) Power map Rapid Hotspot Prediction & Power Distribution at p Base ow Imaging lens To detector IR radiation fluid (a) Through-Wafer Hotspot Imaging Milnes David, Joe Miler, Lewis Hom, Dr. Mehdi Asheghi To resolve tran
De novo stack formation Stacks will, through the program ustacks, use a k-mer search algorithm to merge alleles into loci. First, exactly matching reads are formed into stacks using a hashing algorithm. Stacks are subsequently decomposed into k-mers (subsequences of length k) that are compared among stacks to find matching alleles (see Catchen .
1.1 Piezo-stacks with on-stack-insulation (osi) 5 1.2 Piezo-stacks with in-stack-insulation (isi) 7 2. Aspects of actuator operation 11 2.1 Bulk-stacks or hollow ring-stacks 11 2.2 Mechanics of actuator operation 12 2.3 Mounting advises 14 2.4 Influences from ambient 17 2.5 Electrical operation conditions 18 3. Products, technical data 20
The viticulture industry stacks large volumes of wine barrel inventory on portable steel racks. Individual wine barrel stacks consist of two barrels at each level placed side by side on the rack below. These stacks
Of these stacks, 207 are 500 to 699 feet tall, 63 are 700 to 999 feet tall, and the remaining 14 are 1,000 feet tall or higher. About one-third of these stacks are concentrated in 5 states along the Ohio River Valley. While about half of tall stacks began operating more than 30 years ago, there has been an increase in the number of tall stacks that
Description of selected steel stacks/chimneys . 1. Type of stack circular self-supporting industrial steel stacks 2. Heights of stacks: 30 m ,35m,40m,45m ,50m ,55m,60 m ( short stacks) 3. Top diameter for each stack is taken as minimum h/30 as per provision in IS 6533 :1989 4. Variation in base diameter for each stack for fixed
Energies 2018, 11, 1879 3 of 14 R3 Thermal resistance of the air space between a panel and the roof surface. R4 Thermal resistance of roof material (tiles or metal sheet). R5 Thermal resistance of the air gap between the roof material and a sarking sheet. R6 Thermal resistance of a gabled roof space. R7 Thermal resistance of the insulation above the ceiling. R8 Thermal resistance of ceiling .
10.3.5 Connecting ADC and DAC IPs into a Cortex-M system 242 10.4 243Bring an SoC to life – Beetle test chip case study 10.4.1 Beetle test chip overview 243 10.4.2 Beetle test chip challenges 245 10.4.3 Beetle test chip system design 246 10.4.4 Implementation of the Beetle test chip 24
The parallel chip breaker, that the figure N 1 shows an example, is mainly used in finishing operations. Figure N 1 - Parallel chip breaker Inclined chip breaker The angular type is suitable for most machining operations and is the most difficult to do. The chip is flexed towards the area of the workpiece where is broken without damaging .
