millipede memory
TRANSCRIPT
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By:- Varun Khandelwal
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Content• Millipede memory Introduction. • The Millipede concept.• Cantilever Structure.• Reading data.• Writing data. • Stored bits.• Usage Scenarios.• Current state of the art.• Future challenges.• Conclusion.
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What is millipede ?
• Millipede is a non-volatile computer memory.
• IBM demonstrated a prototype of millipede at CeBIT 2005.
• Data is stored as pits burned into the surface of a thin polymer layer.
• Read and write is done by a MEMS-based probe.
• Seen as potential replacement for magnetic recording in hard drives.
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How it is ?
• Millipede uses thousands of nano-sharp tips to punch indentations representing individual bits into a thin polymer film.
• The 'Millipede' technology is re-writeable.
• Can store more than 3 billion bits of data in the space occupied by just one hole in a standard punch card.
• Their layout looked like the legs of a millipede, and hence the name.
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Need of Millipede ?
• Flash memory cannot surpass 1-2 gigabytes of capacity, whereas Millipede technology could pack 10 - 15 gigabytes of data into the same tiny format.
• Power required will be same as that of flash memory.
• The Millipede can add tremendous data capacity to mobile devices such as PDA, cellular phones.
• Data storage density is 1 Tb/inch^2, equivalent to storing the
content of 25 DVDs on the size of a postal stamp.
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The Millipede concept
• The main memory of modern computers is constructed from number of DRAM-related devices.
• DRAM store data as the presence or absence of electrical charge.
• Hard drive store data on a metal disk.
• Data is represented as local magnetization of the material.
• Reading and writing is accomplished by a single “head”.
• The drive's performance is dependent on how fast the disk spins.
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• Millipede storage combine the best features of both.
• Millipede uses numerous probes,for reading and writing.
• Bits are stored as a pit, in the surface of a thermo-active polymer known as the “sled”.
• The sled is moved in a scanning pattern to bring the requested bits under the probe, a process known as x/y scan.
• The core components of probe storage system are (1) A two-dimensional array of silicon probes (cantilevers) (2) A micro-mechanical scanner which moves the storage
medium relative to the array.
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Animated View of Millipede• An animated view of the
Millipede storage device illustrates how an individual tip creates an indentation in a polymer surface (bottom) and how a large number of such tips are operated in parallel (top).
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What is a Cantilever ?
• Millipede has cantilever array, on which a probe has to be mounted,which is made of silicon.
• For reading, writing and erasing functions, the cantilever tips are brought into contact with the storage medium.
• Most recent array design consists of an array of 64 × 64 cantilevers (4096).
• The storage medium is positioned relative to the cantilever array.
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Reading Data • To accomplish a read, the probe tip is heated to around
300°C and moved in proximity to the data sled.
• If the probe is located over a pit,the surface area increases in contact with the sled, and cools as heat leaks into the sled from the probe.
• The electrical resistance of the probe is proportional of its
temperature.
• Thus when the probe drops into a pit and cools, this registers as a drop in resistance.
• A low resistance will be translated to a "1" bit, or a "0" bit otherwise.
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Thermo-mechanical reading
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Writing data
• To write a bit, the tip of the probe is heated to a temperature above the glass transition temperature of the polymer, which is generally acrylic glass.
• The transition temperature is around 400 K.
• To write a "1", the polymer in proximity to the tip is softened, and then the tip is gently touched to it, causing a dent.
• To erase the bit and return it to the zero state, the tip is instead pulled up from the surface, allowing surface tension to pull the surface flat again
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Thermo-mechanical writing
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Overwriting Data
• To over-write data, the tip makes a series of offset pits that overlap so closely that their edges fill in the old pits, effectively erasing the unwanted data.
• The write or overwrite cycles are limited to 1,00,000 cycles.
• Current data rates of individual tips is limited to kilobits/sec which is few Mbits/sec for entire array.
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Stored bits• Fig. shows that more than
80 percent of the 1,024 cantilevers of an experimental setup were able to write data (12 storage areas at right).
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Usage Scenarios
• Micro Drives Millipede systems can be used for micro drives, like
watches, mobile phones and personal media systems. The very high data density of millipede systems makes
them a very good candidate to be put to this use.
• High-capacity hard drives The Millipede system provides high data density, low seek times, low power consumption and, high reliability. These features make them candidates for
building high capacity hard drives.
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Current state of the art
• The Earlier generation millipede devices used probes 10 nanometers in diameter and 70 nanometers in length, producing pits about 40 nm in diameter on fields 92 µm x 92 µm. This is arranged in a 32 x 32 grid, the resulting 3 mm x 3 mm chip storing 500 megabits of data or 62.5 MB, resulting in an areal density of 200 Gbit/in².
• But recent devices have used a 64 x 64 cantilever chips with a 7 mm x 7 mm data sled, the pit size is about 10 nm, resulting in a areal density just over 1Tbit/in².
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Challenges
• The progress of millipede storage to a commercially useful product has been slower than expected.
• Huge advances in other competing storage systems, notably Flash and hard drives.
• More expensive per megabyte then current technology.
• It has not been surpassed by newer generations of the existing technologies but this can be a great challenge.
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Conclusion
• Today there are many emerging markets for nanotechnology where high density nano storage devices are required.
• It is a nano version of punch card but rewriteable.
• Can be used in micro devices as well as in hard drive manufacturing.
• Millipedes read and write data parallely.
• High storage density of 1Tb/square inch.
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References
• http://www.seagate.com
• IBM Zurich Research
• Millipede project
• T-bit demonstration
• Millipede animation
• IBM Journal Res. Dev. paper
• www.ibm.com
• www.newscientist.com
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Thank you
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Questions