Motorola Demonstrates Viability of
World’s First 4-Megabit Silicon Nanocrystal Memory
DeviceTest Chip Shows
Possibilities of Advanced Memory Technique as a Successor to
FlashAUSTIN, Texas – March 31, 2003
– Motorola, Inc. (NYSE:MOT) has demonstrated the world’s first
4-megabit (Mbit) memory device based on silicon nanocrystals. The fully
functional 4-Mbit test chip represents a major milestone in the search for
successors to floating gate-based flash memories, which many believe will not
continue to scale to smaller geometries. These advances could lead to memories
that are smaller, more reliable and more energy-efficient than floating
gate-based flash memories.
Silicon nanocrystal
memories are part of an advanced class of memory techniques called thin film
storage. Motorola has developed techniques designed to help simplify the
manufacture of these memories. Using traditional deposition equipment,
researchers at Motorola’s DigitalDNA™ Laboratories, deposited
silicon nanocrystals resembling 50-angstrom diameter spheres between two layers
of oxide. The silicon spheres are engineered to hold and prevent lateral
movement of charge to other isolated nanocrystals. This is expected to increase
reliability and scalability because a single oxide defect does not lead to
complete charge loss as in a conventional floating gate nonvolatile
memory.
“Silicon nanocrystal-based memories have the
potential to be an evolutionary replacement for conventional flash memory, which
is widely used in automobiles, appliances, wireless devices and industrial
controls,” said Joe Mogab, vice president, Advanced Products Research and
Development Lab, Motorola’s Semiconductor Products Sector. “As the
first company to demonstrate a 4-Mbit device, we’re one step ahead in
meeting the future needs of the embedded, non-volatile memory market. These
encouraging results suggest that memories based on silicon nanocrystals could be
cost-effectively manufactured with today’s
equipment.”
Flexibility of
FlashFloating gate-based embedded flash memory
is the workhorse of embedded non-volatile memories. Flash memory technology
allows manufacturers to store both software code and data. This flexibility
allows manufacturers to re-program microcontrollers several times in the
development cycle, or store data while operating the controller in the field.
It also makes it easy to adjust to fast-changing market demands or correct
software problems remotely in the field.
However, as the industry begins manufacturing
at smaller geometries – 90nm and smaller – manufacturing floating
gate-based flash becomes impractical. At those dimensions, the chip area spent
on the 9-12V high voltage transistors needed to write and erase the flash
becomes too expensive. Further, engineers cannot reduce the high voltage in
floating-gate based flash without compromising reliability, at the risk of
memory failures and loss of data.
Motorola is
also an industry leader in magnetoresistive random access memory (MRAM). MRAM
has the potential to be a truly revolutionary memory technology, combining the
best attributes of the three major memory types onto a “single” chip
– the density of eDRAM, the speed of eSRAM and the non-volatility of
flash.
Process
BreakthroughMotorola built the test array on
200mm wafers using its 90nm process in the Dan Noble Center at its east-side
campus in Austin, Texas. The key challenge Motorola researchers overcame is
getting the nanocrystals to grow repeatedly to consistent size and density. If
the nanocrystals are too small or too dispersed, then the memory device will not
hold sufficient charge density. The proper charge density is what allows the
memory to detect “on/off” states or 0’s and 1’s. If the
nanocrystals are too large or too dense, the electrons may move either to other
nanocrystals or leak through defects in the tunnel oxide beneath the
nanocrystals. By experimenting with different process chemicals and modifying
conditions such as temperature, pressure and time, Motorola developed a method
to repeatedly grow the nanocrystals with existing semiconductor equipment.
Researchers may now focus on reducing the die size and tightening the technology
specifications in order to be ready for potential products in
2004.
About Motorola’s Semiconductor
Products Sector
As the world's #1 producer of
embedded processors, Motorola's Semiconductor Products Sector creates
DigitalDNA™ system-on-chip solutions for a connected world. Our strong
focus on wireless communications and networking enables customers to develop
smarter, simpler, safer and synchronized products for the person, work team,
home and automobile. Motorola's worldwide semiconductor sales were $4.8 billion
(USD) in 2002. For more information please visit
www.motorola.com/semiconductors About
MotorolaMotorola, Inc. (NYSE:MOT) is a global
leader in providing integrated communications and embedded electronic solutions.
Sales in 2002 were $26.7 billion. Motorola is a global corporate citizen
dedicated to ethical business practices and pioneering important technologies
that make things smarter and life better for people, honored traditions that
began when the company was founded 75 years ago this year. For more information,
please visit:
www.motorola.com#
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