M-RAM%20(Magnetoresistive%20

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M-RAM (Magnetoresistive Random
Access Memory)
Kraków, 7 XII 2004r
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Information flux.
Information transmission
Information Processing
Information storage
Information
Input
Outside word
Output
Magnetic (HDD) Optical (CD, DVD)
DRAM, MRAM
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Memory categories.
WHY DO WEE NEED M-RAM MEMORY ????
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Basic attractions of M-RAM.

• Nonvolatility
• Speed
• Low-power consumption
• Scalability.

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Basic attractions of M-RAM.

• Transfer data to microprocessor
• without
• creating a bottleneck!

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History and development...
M-RAM based on

• M-RAM quick view.
• Magnetoresistivity.

• AMR effect - 80-th.
• GMR effect - 80-th.
• TMR effect 1995 year.

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Storage and states of a bit.
MRAM charge and spin.

• Storage state
• DRAM charge of capacitor.
• Flash, EEPROM charge on floating gate.
• FeRAM charge of a ferroelectric capacitor.

Soft ferromagnet
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Insulator
Hard ferromagnet
TMR
0
Field Oe
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Implementationof 1-MTJ / 1-transistor cell.
NiFe (free layer)
Al2O3 (tunneling barrier)
CoFe (fixed layer)
Ru
SAF
CoFe (pinned layer)
Word line
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Write.
Word line
With digit line current
Without digit line current
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Write.
RA kOhm-um2
Word line
Easy axis field Oe
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Read.
Word line
Word line
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Sizes of MTJ.
Ferromagnet I
NiFe (free layer)
4nm
Al2O3 (tunneling barrier)
1..2nm
Tunnel barrier
CoFe (fixed layer)
3nm
Ru
CoFe (pinned layer)
3nm
Ferromagnet II
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Other MRAM cell architectures.
Twin cell arrays

• Circuit is faster than the 1T1TMR implementation.

• Less atractive on a cell density and cost basis.

Diode cell

• SOI diodes allow the integration of a memory
  with most circuits without sacrificing silicon
  wafer surface area.

• SOI diodes suitable for this aplication havent
  been developed yet.

Transistorless array

• Large reduce in cell area.

• Complex circuity required to read bit state,
  slow read.

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MRAM 32Kb memory segment.
Bit line 31
Bit line 0
Digit line
Word line
Word line
Digit line
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Reference generator.
RMAX
RMIN
Bit line
Digit line
Word line
Wordline
Digit line
RMAX
RMIN
RREF 1/2(RMAX RMIN)
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1Mb MRAM architecture.
Available modes

• Active mode
• Sleep mode
• Standby mode

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Examples and performance of M-RAM technology.

• Motorola semiconductors 2002.

• Freescale semiconductors 2003/2004.

• Technology 0.6um, 5-level metal CMOS, copper
  interconnects
• Capacity 1MB
• Access time 35ns

• Technology 0.18mikrons, 5-level metal CMOS,
  copper interconnects
• Capacity 4MB
• Access time 15-20ns

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Roadmap to future storage technologies.
RRAM with CMR
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Bio MRAM,vision for tomorrow?
Biomolecule labeled by magnetic markers
MRAM array
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References.

• Wyklad z przedmiotu Magnetyczne nosniki
  pamieci, AGH
• Materialy z Uniwersytetu Bielefeld wyklad Thin
  films and nanostructures
• Materialy seminaryjne z Motorola Labs
• Materialy z sympozjum VLSI symposium 2002
• www.freescale.com
• www.motorola.com

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