Seminar On:-

By:-PALLAVI GHODKET.E.COMPRoll No::18

Millipede Memory

Content

Millipede memory Introduction. The Millipede concept. Reading and Writing data. Stored bits. Cantilever Structure. Current state of the art Modern disk Storage Conclusion

What is millipede ?

Millipede is a non-volatile  computer memory  stored on nanoscopic pits burned into the surface of a thin polymer layer, read and written by a MEMS-based probe.

Millipede storage technology is being pursued as a potential replacement for magnetic recording in hard drives.

At launch, it would probably be more expensive per-megabyte than prevailing technologies, but this disadvantage is hoped to be offset by the sheer storage capacity that Millipede technology would offer.

History… Using an innovative nanotechnology,

scientists have demonstrated a data storage density of a trillion bits per square inch – (20 times higher)

Rather than using traditional magnetic or electronic means to store data, Millipede uses thousands of nano-sharp tips to punch indentations representing individual bits into a thin plastic film.

The 'Millipede' technology is re-writeable (meaning it can be used over and over again), and may be able to store more than 3 billion bits of data in the space occupied by just one hole in a standard punch card.

Millipede Storage Chips

MEMS Based Device

Bitwise Data Storage

Need of Millipede ? Flash memory is not expected to surpass 1-2 gigabytes of

capacity in the near term, Millipede technology could pack 10 - 15 gigabytes of data into the same tiny format, without requiring more power for device operation.

"The Millipede project could bring tremendous data capacity to mobile devices such as personal digital assistants, cellular phones, and multifunctional watches,“

Using revolutionary nanotechnology, scientists have

made it to the millionths of a millimeter range, achieving data storage densities of more than one terabit (1000 gigabit) per square inch, equivalent to storing the content of 25 DVDs on an area the size of a postage stamp.

The Millipede concept The main memory of modern computers is constructed from number

of DRAM-related devices. DRAM basically consists of a series of capacitors, which store data as the presence or absence of electrical charge. Each capacitor and its associated control circuitry, referred to as a cell, holds one bit, and bits can be read or written in large blocks at the same time.

Hard drives store data on a metal disk that is covered with a magnetic material; data is represented as local magnetization of this material.

Millipede storage attempts to combine the best features of both. Like the hard drive, millipede stores data in a "dumb" medium that is simpler and smaller than any cell used in an electronic medium.

What is a Cantilever ?

The core components of probe storage system are a two-dimensional array of silicon probes (cantilevers) and a micro-mechanical scanner which moves the storage medium relative to the array.

For the device to perform its reading, writing and erasing functions, the cantilever tips are brought into contact with the storage medium — a thin film of a custom designed cross-linked polymer coated on a silicon substrate, which is moved in the x- and y-directions. The storage medium is positioned with nanometer-scale accuracy relative to the cantilever array.

About used Cantilevers The cantilevers used in the array are of a

three-terminal design, with separate heaters for reading and writing, and a capacitive platform for electrostatic actuation of the cantilevers in the z-direction.

The cantilevers are approximately 70 µm long, with a 500-700 nm long tip integrated directly above the write heater. The apex of each tip has a radius on the scale of a few nanometers allowing data to be written at extremely high densities

Animated View of Millipede

•The core of the Millipede Project.

>2D array>Operations

Performed

Technical background

Writing data Bits are written by heating

a resistor built into the cantilever to a temperature of 400 degrees Celsius.

The hot tip softens the polymer and briefly sinks into it,&

generating an indentation.

Reading Data

For reading, the resistor is operated at lower temperature, typically 300 degrees Celsius, which does not soften the polymer.

When the tip drops into an indentation, the resistor is cooled by the resulting better heat transport, and a measurable change in resistance occurs.

Overwriting Data

To over-write data, the tip makes a series of offset pits that overlap so closely their edges fill in the old pits, effectively erasing the unwanted data.

The write or overwrite cycles are limited to 1,00,000 cycles.

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).

Stored bits

The close-ups (center) present 40 nm (nanometers) wide indentations at a "pitch" (distance between centers of neighboring indentations) of 120 nm (left) and 40 nm (right), pitch. 

Millipede Cantilever

Closed View Of Millipede

Zoom to a section of the Millipede cantilever array as seen in an optical microscope. 

Modern disk Storage

IBM 353

IBM 2310IBM 350

Current state of the art

The progress of millipede storage to a commercially useful product has been slower than expected.

Huge advances in Flash and hard drives, has made the existing demonstrators unattractive for commercial production.

Millipede appears to be in a race, it has not

been surpassed by newer generations of the existing technologies by the time it is ready for production.

Conclusion

Today there are no known emerging markets for nanotechnology where high density storage devices.