Download Emerging Memory Technologies OUM (Ovonic Unified Memory)

Emerging Memory
Technologies
Presented By
Ananth Hegde
Ashwini Dwarakanath
CSE597E
OUM (Ovonic Unified Memory)
Operation
• Chalcogenide material alloys used material alloys used
in re-writable CDs and DVDs
• Electrical energy (heat) converts the material between
crystalline (conductive) and amorphous (resistive)
phases
• Cell reads by measuring resistance Conductive=>0
Resistive => 1
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OUM Attributes
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Non-volatile
High density
Non-destructive read
Low voltage and low power
~1012 write/erase cycles
Easy to integrate w/ logic
Poly Crystalline
Structure & electric property of
phase change materials
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Device resistance vs. pulse width
Chalcogenide Resistance vs
Temperature
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VI Characteristics
SET – RESET Currents
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OUM Test Chip
• Functional Ovonics Unified memory Array has
been demonstrated in a 0.18um integrated
CMOS logic process
• Endurance demonstrated to 1012 set-reset
cycles
• Direct 3.3V operation without the use of an on
chip charge pump
• This technology offers the potential of easy
addition of non-volatile memory to a standard
CMOS process, is low cost and highly scalable
Memory Array
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Array Characteristics
Technology Challenges
• Reduction of programming current for
lower voltage and lower power operation
• Increased set/reset resistance and
decreased read current/set current margin
with scaling -> impact on read
performance/margin
• Management of proximity heating with
declining cell space -> disturb risk
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Polymer Memory Attributes
• Very low cost/bit, high
capacity per dollar
Simple processing,
easy to integrate with
other CMOS
• Low power
consumption
• PFRAM low-cost/high
capacity fits well in
handheld data storage
applications
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Technology Camps
OUM
• Ovonyx
• Intel
• ST Micro
• British Aerospace
MRAM
• IBM
• Motorola
• Infineon
FeRAM
• Matsuhita
• Motorola
• Micron
• NEC
• Fujitsu
• Toshiba
• Samsung
• Hitachi
• IBM / Infineon
PFRAM
• Intel
• AMD
• Coatue
Technology Comparison
MRAM
Fastest Read
and Write,
Unlimited
Cycles
FeRAM
OUM
Fastest
Fastest Read
Read and
and Write,
Write, 1012
1012 Cycles
Cycles
Non
Destructive
Read
Destructive
Read
Special
Process
Larger Cell
Size
Special
Process
Larger Cell
Size
Non
Destructive
Read
“Bolt on”
Process
Smaller Cell
Size
Polymer
Slow Read
and Write,
Unlimited
Cycles?
Non
Destructive
Read
?
Smaller Cell
size
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A Comparative chart for memory
specifications
Summary
• All 3 claim similar performance advantages: low voltage
operation, long life span and very high speed.
• FeRAM has lower, though comparable read and write
times. However MRAM has a higher promise to be
denser and so less expensive.
• O.U.M. can be read and written to trillions of times,
making its use essentially nondestructive, unlike MRAM
or FRAM, while O.U.M. again is not as fast as MRAM
• While MRAM and O.U.M. would require the addition of
six to eight "masking" layers in the chip-manufacturing
process, just like flash, FRAM might require as little as
two extra layers.
• The biggest problem with MRAM is a relatively small
difference, difficult to detect, between its "on" and "off"
states.
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Summary
• Only FRAM is produced today, though the low memory
capacity of current chips (64KB) has restricted it to
telemetry applications.
• MRAM has already surpassed FRAM in capacity,
achieving a 256KB figure a scant three years into its
development cycle, but fabrication issues still need to be
sorted out.
• OUM's prospects are even less clear. While its basic
materials technology has already proven successful in
recordable optical discs, the one major chip
manufacturer committed to OUM development—Intel—
isn't saying much.
• But perfecting any of them would have significant
consequences, effectively obsolescing Flash, permitting
the fabrication of complete systems-on-a-chip (making
for even smaller devices) and ultimately even replacing
all but the fastest solid-state memories.
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