《Heat Assisted Magnetic Storage (HAMR) - integrated lasers and plasmonicsfor ultra-high density data storage.pdf》由会员分享,可在线阅读,更多相关《Heat Assisted Magnetic Storage (HAMR) - integrated lasers and plasmonicsfor ultra-high density data storage.pdf(47页珍藏版)》请在三个皮匠报告上搜索。
1、Heat Assisted Magnetic Storage(HAMR)-integrated lasers and plasmonicsfor ultra-high density data storageTechnology Case StudyPresenter:Dr Richard Pitwon,SeagateTechnology Case StudySpecial Focus:OpticsOPTICS3OverviewOptical interconnect and integration in hyperscale data centres The need for ultra-h
2、igh capacity data storage Hard disk drive read and write principles Areal density trilemma Heat Assisted Magnetic Recording(HAMR)HAMR head architecture Materials and reliability challenges in HAMR headsSection Title 2Subtitle4Optical interconnect in hyperscale environments5Hyperscale is now the domi
3、nant type of data centreOptical interconnect intrinsic to hyperscale data centres6Seagate UK made substantial advances over the past 8 years in:Optically integrated data centre systems(storage switch systems)Subsystems(disk drives)Advances in hyperscale optical interconnect7Object oriented Ethernet
4、controller with interchangeable optical mezzanine cardsPegasus(NephDem06.01)Optically disaggregated object oriented platformSystem level optical interconnect advances8Pegasus(NephDem06.01)Optically disaggregated object oriented platformObject oriented Ethernet controller with interchangeable optical
5、 mezzanine cardsSystem level optical interconnect advances9Pegasus(NephDem06.01)Optically disaggregated object oriented platformSystem level optical interconnect advances10Pegasus(NephDem06.01)Optically disaggregated object oriented platformSystem level optical interconnect advancesStandard Kinetic
6、drive receptacleTo connect to Kinetic driveBoard-to-board power connectorMurata FOT2+2 optical engineFireLight connector64 channel optical array interface2 channels illuminated11Pegasus(NephDem06.01)Optically disaggregated object oriented platformSystem level optical interconnect advances12Aurora(Ph
7、oxDem09.03)Multimode optical interconnect platformUniversal optical mezzanine cardsSystem level optical interconnect advances1st Generation-Vertical CouplingFigure courtesy:FHG IZMFirst international standard for micro-photonic test boardsH2020 COSMICC silicon photonic CWDM transceiverGlass waveguid
8、e backplane2nd Generation-Adiabatic Coupling13Aurora(PhoxDem09.03)Multimode optical interconnect platformSinglemode silicon photonics transceiverChip level optical interconnect advancesMedium reach CWDM singlemode silicon photonics transceiverUniversal optical mezzanine cards14Aurora(PhoxDem09.03)Mu
9、ltimode optical interconnect platformSinglemode silicon photonics transceiverChip level optical interconnect advancesMedium reach CWDM singlemode silicon photonics transceiverUniversal optical mezzanine cards15Section Title 2Photonic Integrated CircuitsCombining the ability to guide light and change
10、 the speed of light opens the door to:ModulationSplittingSwitchingWavelength MUX/DEMUXLithium Niobate LiNbO3SiliconIndium PhosphideSilicon NitrideSilica(glass)PolymerBarium Titanate BTOOptical transceiversQuantum techWearable diagnosticsWDM switchingLIDARSource:MIT Lincoln LaboratorySource:Rockley P
11、hotonicsNeuromorphic computingSensorsSource:GenalyteHAMRIntegrated photonics form the basis of diverse applicationsSeagate InternalHigh-Capacity Digital StorageSeagate InternalDemand for High-Capacity StorageSource:Data Age 2025,sponsored by Seagate with data from IDC Global Datasphere,Nov 2018Growt
12、h in created data is explodingHard Disk Drives(HDDs)dominate the Cloud exabyte market Solid State Drives(SSDs)better for performance-sensitive,highly transactional workloads closer to compute nodes.Hard Disk Drives(HDDs)provide best TCO for the vast majority of cloud workloads.Seagate InternalHard D
13、rive ComponentsWaferBarHead StackMediaHGAHard DriveSliderSeagate InternalMagnetic regionsAreal Density1 Tb/in2Magnetic domainsLinear Density(down-track)Track Density(cross-track)The material of the main magnetic medium layer is usually a cobalt-based alloy e.g cobalt,platinum and chromiumMagnetic su
14、rface of each platter is divided into small sub-micron magnetic regions,representing a bitWhen cooled below Curie temperature,magnetization of a piece of ferromagnetic material spontaneously divides into many small regions called magnetic domains.51 nm13 nmGrain of polycrystalline magnetic material
15、contains many domainsBy Gorchy-Own work,CC BY-SA 3.0,https:/commons.wikimedia.org/w/index.php?curid=4459327Seagate InternalReading and writing on a magnetic platterRead elementGMR sensor which reads changes in resistance for different magnetic field orientationsWrite elementElectromagnet creates mag
16、netic field between polesAreal Density for LMR0.3 Tb/in2Longitudinal Magnetic Recording(LMR)ShieldSeagate InternalPerpendicular Magnetic Recording(PMR)Read elementGMR sensor which reads changes in resistance for different magnetic field orientationsWrite elementElectromagnet creates magnetic field b
17、etween poles with asymmetric flux densityReading and writing on a magnetic platterAreal Density for PMR1 Tb/in2Soft underlayerSeagate InternalAerodynamic engineeringGap or“Flying Height”5 nmIn order to further increase bit density,the Flying Height must be minimisedIn order to maintain 5 nm gap betw
18、een head and platter,the head acts as an air bearing surface(ABS)The platter surface roughness is less than 0.1 nm or 1Seagate InternalRecording Head ArchitectureHead Gimbal Assembly(HGA)“BEOL”InterconnectsSeagate InternalRecording Head Architecture0.3mm2300 devicesWriter-over-Reader“BEOL”Interconne
19、ctsRead SensorWriter pole tipTCR contact sensorProtrusion heatersSeagate InternalAreal Density TrilemmaSNRlog10(N)=1ReadabilityThermal StabilityWriteabilityIn order to increase arial density reduce size of magnetic bitN=number of grains in the magnetic bitBUT reducing N reduces SNRTherefore you must
20、 reduce grain volume VReducing grain volume V reduces the thermal stability,so you must increase magnetic anisotropy KBUT increasing magnetic anisotropy requires stronger magnetic write field Hwrite to flip the domainSeagate InternalAreal Density TrilemmaSNRlog10(N)=1ReadabilityThermal StabilityWrit
21、eabilityFe65Co35Seagate InternalAreal Density Trilemma19972022Seagate InternalWhy Do We Need HAMR Recording?Maximum capability of perpendicular recording has been reached!Areal Density ExplainedAreal DensityPerpendicular Media GrainsLinear Density(down-track)Track Density(cross-track)Seagate Interna
22、lFlux density too low to orient magnetic mediaHeat Assisted Magnetic Recording(HAMR)Conceptcoercivitytemperatureambient temperatureheatingcoolingwritestoreHeat a spot on the magnetic media to reduce coercivityNow magnetic media responds to magnetic fluxSwitch off heat to rapidly cool media increasin
23、g its coercivity and locking bit into placeMagnetic coercivity is a measure of the ability of a ferromagnetic material to withstand an external magnetic field without becoming demagnetized.Seagate InternalReading and writing on a magnetic platterLaser and near field transducer(NFT)Hear Assisted Magn
24、etic Recording(HAMR)ShieldAreal Density for HAMR3 Tb/in2Seagate InternalThe Diffraction LimitDiffraction limits the minimum optical spot size of focused propagating light waves.In a Blu-Ray drive,=402 nm and sin=0.85.This gives a spot size of 238 nm.By todays definition of track pitch in a HDD,this
25、is huge.Seagates early HAMR heads used immersion near-field recording.This enabled confinement to 100 nm.The simple solution is to just block the light with a screen and poke a small hole in it.The amount of light T,of wavelength,you can get through a circular hole of radius r,scales as the ratio of
26、 the hole diameter to the wavelength to the 4th power.This means if I make the hole smaller by a factor of 2,we need 16x more power to get the same amount of light through.Small holes are just not practical since you waste so much power at high areal densitiesd 642724Seagate InternalNear Field Trans
27、ducerLight hits the gold disk and is converted into surface plasmons(bound states of charge and EM fields).These surface plasmons travel along the edge of the disk and down the peg.The moving charges in the peg produce an electric field that induce charge motion in the media grains.The media materia
28、l is lossy,generating heat in the recording media.The heated area in the media is roughly the size of the peg.The media is designed to control the heat spread and the cooling rate.By using an NFT,a very small thermal spot is created(20 80 nm).Seagate Internal34Physics of HAMR Recordinglaser+matched
29、NFT disc size Quadrupole surface plasmon resonanceNote:opposite light direction from prior page!Antenna Field confinementABS viewNear field transducer has two components:1.NFT Disc transduction of photons to plasmons AND extracting heat from peg2.NFT Peg energy transfer from disc to media for heatin
30、gSeagate Internal35Physics of HAMR Recording830 nm solid state laser on back of sliderLarge-area input coupler to capture free space lightModify mode index to couple light into core low-loss propagationSeagate InternalHeat-Assisted Magnetic RecordingSeagate InternalHAMR Head ArchitectureElectromagne
31、t writer(old)+solid state laser(new)+optical lightpath(new)+nanofocusing optics(new)Laser planar waveguide solid immersion mirror near field transducerLollipop NFT for plasmon resonance disc+antennaSloped write pole to avoid power absorption from light tailSeagate InternalHAMR Head ArchitectureSlide
32、rRecordingHeadLaserLaserCarrierSeagate InternalSeagates HAMR Areal Density ProgressionSeagate|39Richard Pitwon Advances in Heat Assisted Magnetic Recording(HAMR)Seagate InternalFirst commercial deployment of HAMR technologies in 2023Seagate InternalThe evolution of heat assisted magnetic recordingHA
33、MR draws from a very wide range of materials science and physics disciplines to workPerformance and reliability progress has relied on nano-scale control of metal and dielectric filmsSeagate Northern Ireland Cleanroom area 87,000 sq ft,Staff 1600 Site established 1993 The largest of only 5 facilitie
34、s of its type in the world One of two Wafer fabs in Seagate Supplies around 25%of global demand for read-write heads for hard drivesSeagate 43Seagate InternalSeagate in UK-Skills and TalentSeagate is a key contributor to two Centres of Doctoral Training in Photonics and Compound Semiconductors,with
35、an extensive industrial network.Seagate InternalChallenge 1:Innovation capacity for nano-photonic chipsChallenge 2:Manufacturing productivity enabled by industrial digitalisationConclusionConclusionHyperscale data centres are a microcosm for the optical,photonics and quantum technology eco-systemNee
36、d for ultra-high speed data networking and computer processing matched by need for ultra-high data storage Heat Assisted Magnetic Recording(HAMR)enables unprecedented storage densities in hard disk drivesHAMR will require advanced laser and PIC integration into commodity high-volume hard drivesIn 2023 the first commercial HAMR drives were sold with capacity of 30 TBThis will make HAMR one of the highest volume integrated photonics subsystemsThank you!Open Discussion