Magnetic RAM: The Universal Memory

Magnetic RAM: The Universal Memory

OverviewIntroductionHistorical perspectiveTechnical DescriptionChallengesPrincipalsMarket impactsSummary OverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Introduction Non-volatileInformation is saved even when there is no powerImmediate boot upNo need to wait for your computer to boot upMRAM, SRAM and DRAMMRAM is potentially capable of replacing both DRAM, SRAM and many advantages over technology currently used in electronic devicesOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Introduction DRAMAdvantages: cheapDisadvantages: Comparatively slow and loses data when power is offSRAMAdvantages: fast Disadvantages: cost up to 4 times as much as DRAM loses data when power is offFlash memoryAdvantages: save data when power is offDisadvantages: saving data is slow and use lot of powerOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Historical OverviewWhy MRAM Became an Important Research TopicUniversal Memory (Computing & Electronics)Instant-On ComputingRead & Write to Memory FasterReduced Power ConsumptionSave Data in Case of a Power FailureModern MRAM Technology Emerged from Several Technologies :Magnetic Core MemoryMagnetoresistive RAMGiant MagnetoresistanceOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Magnetic Core MemoryIn 1953 a team at MIT called Whirlwind introduced the magnetic core memoryMagnetic core memory utilized arrays of thousands of small ring magnets threaded with wires

Data bits were stored and manipulated by sending electric current pulses through the magnetsMagnetic cores were the most reliable and inexpensive memories for almost twenty years

Photo Courtesy: Magnetism Group, Trinity College, DublinOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Giant Magnetoresistance MaterialsOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummaryGiant Magnetoresistance Materials (GMR) were discovered in 1989By 1991 GMR technology provided a magnetoresistance ratio of 6% (3 times that provided by previous technologies)Read access time of 50 ns (9 times improvement)Still not as fast as semiconductor memoryLarge size because lines of 1micron were required

Technical OverviewOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary3 MRAM Technologies are Currently Being DevelopedHybrid Ferromagnet Semiconductor StructuresMagnetic Tunnel JunctionsAll-Metal Spin Transistors & Spin ValvesWriting Data to a Cell is Similar for all 3 TechnologiesReading a Cells Data Reads the Direction of Magnetization of a Ferromagnetic Element, but the Method Varies for Each Technology

Basic PrinciplesOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummaryThe 2 Possible Magnetization States of a Ferromagnetic Element can be Described by a Hysteresis LoopMagnetization of Film vs. Magnetic FieldDiagram Courtesy: IEEE SpectrumA magnetic field, with magnitude greater than the switching field, sets magnetization in direction of applied field

Writing a BitOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummaryMRAM Utilizes a Wire Directly Over & Magnetically Coupled to the Magnetic ElementA Current Pulse Traveling Down the Wire Creates a Magnetic Field Parallel to the WireEach Cell is Inductively Coupled with a Write Wire From a Row & a Column

Diagram Courtesy: IBM

Hybrid Ferromagnet Semiconductor StructuresOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummaryA Ferromagnetic Element is Placed Directly Over a Semiconducting ChannelThe Fringe Field has a Large Component Perpendicular to the Plane of the ChannelDiagram Courtesy: IEEE Spectrum

Magnetic Tunnel JunctionsOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary2 Ferromagnetic Films Separated by a Dielectric Tunnel BarrierResistance Between Films Depends on their Magnetic StatesParallel Fields: Low ResistanceAntiparallel Fields: High ResistanceDiagram Courtesy: IEEE Spectrum

ComparisonOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummaryHybrid Ferromagnet Semiconductor:Problems with Cross-Talk Between CellsCompatable with Standard CMOS ProcessingMagnetic Tunnel JunctionFabrication Requirements Cause Problems with Operating Margins and YieldsNot Compatable with Standard CMOS ProcessingAll-Metal Spin ValveLow Impedance, Low Readout VoltageNot Compatable with Standard CMOS Processing

Current Challenges

InterferenceManufacturing UniformityPower efficiencySize

OverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Interference

Interference between adjacent cellsDisturbance by digit line current to adjacent line currentThe effect of heat cause bit flipOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Manufacturing

As chips get smaller the individual circuits hold less of the chargeRisks of leaking current and other problemsHard to integrate with other silicon-based chips The resistance of the magnet device varies exponentially with it thicknessOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Uniformity

Distribution of the electromagnetic field

OverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Power efficiency

High Current consumptionMRAM designs required a relatively high current to write each single bit

Power consumption is significantly greater than DRAM, only 99% of the total power is used in delivering electric current for writing data

One transistor is required for each memory bit

OverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

The PlayersOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Principal Players:

Additional Players:Bosch- Hewlett-PackardIntel- NVE CorporationSiemens - SonyToshiba

Impacts on Broader SocietyOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Engineers / ScientistsDesigning MRAMDesigning Hardware/Software that Interacts with MRAMNew Memory StandardsSocietyAdded ConvenienceLonger Battery Life on Portable ElectronicsInstant-On ComputingHigher ProductivityData not Lost in Power FailureFaster Read & Write

Market impactsHuge demand of memoryMRAM is expected to be the standard memory The market size was $21 billion in 1999 when DRAM came out$48 billion in 2001$72 billion within 2007 with MRAM

OverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Market analysis IBM being the leader in the development of MRAM is chase by:MotorolaIntelSiemensToshibaOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Next 5 yearsIBM and Infineon are planning the mass production for 2004MRAM will become the standard memory for the next couple of yearMRAM will be use in other devices

OverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

I&O long term Digital cameraCellular phonesPDAPalm pilotMP3HDTVOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Quality of life impactsMRAM will eliminate the boot up timeElectronic devices will be more power efficientIt could enable wireless video in cell phonesMore accurate speech recognitionMP3, instead of hundred on songs, MRAM will enable thousand of songs and movies

OverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

ImportancePotentially Substantial Impact on SocietyPotentially Central to Computers and Electronics that Engineers are Designing The Future of MRAMExpected to Replace SRAM, DRAM, & FLASHPredicted to be the Memory Standard in both Computers & Consumer ElectronicsIndicators of a BreakthroughPrice of MRAM is Equivalent to or Only Slightly More than DRAM & FLASHMRAM is More Common in New PCs than DRAM & More Common in New Electronics than FLASHSummaryOverviewIntroductionHistorical PerspectiveTechnical DescriptionChallenges / ConstraintsPrincipalsMarketSummary

Bonsor, Kevin. How Magnetic RAM Will Work. 9 Feb 2003. .Daughton, James. Magnetoresistive Random Access Memory (MRAM). 4 Feb 2000. 1-13. 13 Feb 2003. .Goodwins, Rupert. Magnetic Memory Set to Charge the Market. ZDNet UK. 12 Feb 2003. 16 Feb 2003. .Guth, M., Schmerber, G., Dinia, A. Magnetic Tunnel Junctions for Magnetic Random Access Memory Applications. Materials Science and Engineering. Online 2 Jan 2002: 19. Science Direct. 16 Feb 2003. . IBM Magnetic RAM Images. 16 Feb 2003. .Johnson, Mark. Magnetoelectronic memories last and last. IEEE Spectrum 37 (2000