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					Magnetic RAM: The Universal
          Memory
                      Overview
Overview
Introduction   •   Introduction
Historical     •   Historical perspective
Perspective
               •   Technical Description
Technical
Description    •   Challenges
Challenges /   •   Principals
Constraints    •   Market impacts
Principals     •   Summary
Market
Summary
                         Introduction
Overview
Introduction   • Non-volatile
Historical        – Information is saved even when there is
Perspective         no power
Technical      • Immediate boot up
Description       – No need to wait for your computer to boot up
               • MRAM, SRAM and DRAM
Challenges /
Constraints       – MRAM is potentially capable of replacing
                    both DRAM, SRAM and many advantages
Principals          over technology currently used in electronic
                    devices
Market
Summary
                        Introduction
               • DRAM
Overview          – Advantages: cheap
Introduction      – Disadvantages: Comparatively slow
                    and loses data when power is off
Historical
               • SRAM
Perspective
                  – Advantages: fast
Technical         – Disadvantages: cost up to 4 times as
Description         much as DRAM loses data when power
Challenges /        is off
Constraints    • Flash memory
Principals
                  – Advantages: save data when power is
                    off
Market            – Disadvantages: saving data is slow and
Summary
                    use lot of power
                     Historical Overview
               • Why MRAM Became an Important Research Topic
Overview
                 – Universal Memory (Computing & Electronics)
Introduction
                 – “Instant-On” Computing
Historical       – Read & Write to Memory Faster
Perspective
                 – Reduced Power Consumption
Technical        – Save Data in Case of a Power Failure
Description
             • Modern MRAM Technology Emerged from
Challenges /   Several Technologies :
Constraints
                 – Magnetic Core Memory
Principals       – Magnetoresistive RAM
Market           – Giant Magnetoresistance
Summary
                 Magnetic Core Memory
Overview       • In 1953 a team at MIT called Whirlwind
                 introduced the magnetic core memory
Introduction
                • Magnetic core memory utilized arrays of
Historical         thousands of small ring magnets threaded
Perspective        with wires
Technical      • Data bits were stored and
Description       manipulated by sending
Challenges /      electric current pulses through
Constraints       the magnets
Principals     • Magnetic cores were the most
                 reliable and inexpensive
Market           memories for almost twenty      Photo Courtesy: Magnetism Group,
                                                 Trinity College, Dublin

Summary          years
               Giant Magnetoresistance
                      Materials
Overview
             • Giant Magnetoresistance Materials (GMR) were
Introduction
               discovered in 1989
Historical   • By 1991 GMR technology provided a
Perspective    magnetoresistance ratio of 6% (3 times that
Technical      provided by previous technologies)
Description  • Read access time of 50 ns (9 times improvement)
Challenges / • Still not as fast as semiconductor memory
Constraints
             • Large size because lines of 1micron were
Principals     required
Market
Summary
                   Technical Overview
Overview
             • 3 MRAM Technologies are Currently Being
Introduction   Developed
Historical      – Hybrid Ferromagnet Semiconductor Structures
Perspective     – Magnetic Tunnel Junctions
                – All-Metal Spin Transistors & Spin Valves
Technical
Description  • Writing Data to a Cell is Similar for all 3
               Technologies
Challenges /
Constraints
             • Reading a Cell’s Data Reads the Direction of
               Magnetization of a Ferromagnetic Element, but
Principals     the Method Varies for Each Technology
Market
Summary
                        Basic Principles
Overview
             • The 2 Possible
Introduction   Magnetization States
Historical     of a Ferromagnetic
Perspective    Element can be
               Described by a
Technical      Hysteresis Loop
Description
             • Magnetization of Film
Challenges /   vs. Magnetic Field
Constraints                                  Diagram Courtesy: IEEE Spectrum


Principals
              • A magnetic field, with magnitude greater than the
                switching field, sets magnetization in direction of
Market          applied field
Summary
                         Writing a Bit
             • MRAM Utilizes a Wire Directly Over &
Overview       Magnetically Coupled to the Magnetic Element
Introduction • A Current Pulse Traveling Down the Wire
               Creates a Magnetic Field Parallel to the Wire
Historical
Perspective • Each Cell is Inductively Coupled with a Write
               Wire From a Row & a Column
Technical
Description
Challenges /
Constraints
Principals
Market
Summary                        Diagram Courtesy: IBM
                 Hybrid Ferromagnet
               Semiconductor Structures
Overview     • A Ferromagnetic Element is Placed Directly
Introduction   Over a Semiconducting Channel
             • The Fringe Field has a Large Component
Historical
               Perpendicular to the Plane of the Channel
Perspective
Technical
Description
Challenges /
Constraints
Principals
Market
Summary                      Diagram Courtesy: IEEE Spectrum
                      Magnetic Tunnel
                        Junctions
             • 2 Ferromagnetic Films Separated by a Dielectric
Overview
               Tunnel Barrier
Introduction • Resistance Between Films Depends on their
Historical     Magnetic States
Perspective • Parallel Fields: Low Resistance
Technical    • Antiparallel Fields: High Resistance
Description
Challenges /
Constraints
Principals
Market
Summary                      Diagram Courtesy: IEEE Spectrum
                            Comparison
Overview       • Hybrid Ferromagnet Semiconductor:
                  – Problems with Cross-Talk Between Cells
Introduction
                  – Compatable with Standard CMOS Processing
Historical     • Magnetic Tunnel Junction
Perspective
                  – Fabrication Requirements Cause Problems with
Technical           Operating Margins and Yields
Description       – Not Compatable with Standard CMOS Processing
Challenges /   • All-Metal Spin Valve
Constraints       – Low Impedance, Low Readout Voltage
                  – Not Compatable with Standard CMOS Processing
Principals
Market
Summary
                    Current Challenges
Overview
Introduction
Historical     •   Interference
Perspective    •   Manufacturing
Technical
Description
               •   Uniformity
Challenges /
               •   Power efficiency
Constraints    •   Size
Principals
Market
Summary
                      Interference
Overview
Introduction   -Interference
Historical     between adjacent
Perspective    cells
Technical      -Disturbance by
Description    digit line current to
Challenges /   adjacent line current
Constraints
               -The effect of heat
Principals
               cause bit flip
Market
Summary
                      Manufacturing
Overview
               • As chips get smaller the individual
Introduction     circuits hold less of the charge
Historical     • Risks of leaking current and other
Perspective      problems
Technical      • Hard to integrate with other silicon-based
Description      chips
Challenges /   • The resistance of the magnet device
Constraints      varies exponentially with it thickness
Principals
Market
Summary
                     Uniformity
Overview
Introduction   -Distribution of the electromagnetic field
Historical
Perspective
Technical
Description
Challenges /
Constraints
Principals
Market
Summary
                     Power efficiency
Overview       • High Current consumption
Introduction     – MRAM designs required a relatively
                   high current to write each single bit
Historical
Perspective
Technical      • Power consumption is significantly
Description      greater than DRAM, only 99% of the total
                 power is used in delivering electric
Challenges /
Constraints      current for writing data
Principals
               • One transistor is required for each
Market
                 memory bit
Summary
                                The Players
Overview       • Principal Players:
Introduction
Historical
Perspective
Technical
Description
Challenges /   • Additional Players:
Constraints       –   Bosch           - Hewlett-Packard
Principals        –   Intel           - NVE Corporation
                  –   Siemens         - Sony
Market
                  –   Toshiba
Summary
                    Impacts on Broader
                         Society
Overview       • Engineers / Scientists
Introduction      – Designing MRAM
                  – Designing Hardware/Software that Interacts with
Historical
                    MRAM
Perspective
                  – New Memory Standards
Technical      • Society
Description
                  – Added Convenience
Challenges /         • Longer Battery Life on Portable Electronics
Constraints          • “Instant-On” Computing
                  – Higher Productivity
Principals
                     • Data not Lost in Power Failure
Market               • Faster Read & Write

Summary
                     Market impacts
Overview
Introduction
               • Huge demand of memory
Historical       – MRAM is expected to be the standard
Perspective        memory
Technical      • The market size was $21 billion in
Description
                 1999 when DRAM came out
Challenges /
Constraints
               • $48 billion in 2001
Principals
               • $72 billion within 2007 with
                 MRAM
Market
Summary
                    Market analysis
Overview
Introduction
Historical
               • IBM being the leader in the
Perspective      development of MRAM is chase by:
Technical      • Motorola
Description
               • Intel
Challenges /
Constraints    • Siemens
Principals     • Toshiba
Market
Summary
                       Next 5 years
Overview
Introduction
Historical     • IBM and Infineon are planning the
Perspective
                 mass production for 2004
Technical
Description    • MRAM will become the standard
Challenges /
                 memory for the next couple of year
Constraints    • MRAM will be use in other devices
Principals
Market
Summary
                       I&O long term
Overview
Introduction
             •   Digital camera
Historical
Perspective •    Cellular phones
Technical    •   PDA
Description •    Palm pilot
Challenges / •   MP3
Constraints
             •   HDTV
Principals
Market
Summary
                 Quality of life impacts
Overview
               • MRAM will eliminate the boot up time
Introduction
               • Electronic devices will be more power
Historical       efficient
Perspective    • It could enable wireless video in cell
Technical        phones
Description    • More accurate speech recognition
Challenges /   • MP3, instead of hundred on songs,
Constraints      MRAM will enable thousand of songs
                 and movies
Principals
Market
Summary
                               Summary
               • Importance
Overview
                  – Potentially Substantial Impact on Society
Introduction      – Potentially Central to Computers and Electronics that
                    Engineers are Designing
Historical
Perspective    • The Future of MRAM
                  – Expected to Replace SRAM, DRAM, & FLASH
Technical
                  – Predicted to be the Memory Standard in both
Description
                    Computers & Consumer Electronics
Challenges /   • Indicators of a Breakthrough
Constraints       – Price of MRAM is Equivalent to or Only Slightly
Principals          More than DRAM & FLASH
                  – MRAM is More Common in New PCs than DRAM
Market              & More Common in New Electronics than FLASH
Summary
                                References
               • Bonsor, Kevin. How Magnetic RAM Will Work. 9 Feb 2003.
Overview         <http://computer.howstuffworks.com/mram.htm>.
               • Daughton, James. Magnetoresistive Random Access Memory
Introduction     (MRAM). 4 Feb 2000. 1-13. 13 Feb 2003.
                 <http://www.math.uwaterloo.ca/~m2wang/cs690b/mram.pdf>.
Historical     • Goodwins, Rupert. Magnetic Memory Set to Charge the Market.
Perspective      ZDNet UK. 12 Feb 2003. 16 Feb 2003.
                 <http://techupdate.zdnet.co.uk/story/0,,t481-s2130312,00.html>.
Technical
               • Guth, M., Schmerber, G., Dinia, A. “Magnetic Tunnel Junctions
Description      for Magnetic Random Access Memory Applications.” Materials
Challenges /     Science and Engineering. Online 2 Jan 2002: 19. Science
                 Direct. 16 Feb 2003. <http://www.sciencedirect.com>.
Constraints
               • IBM Magnetic RAM Images. 16 Feb 2003.
Principals       <http://www.research.ibm.com/resources/news/20001207_mrami
                 mages.shtml>.
Market         • Johnson, Mark. “Magnetoelectronic memories last and last.”
                 IEEE Spectrum 37 (2000 Feb): 33-40.
Summary

				
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