MILLIPEDE MEMORYMEMS BASED MEMORY DEVICE FROM IBM

CONTENTS :

Millipede memory Introduction. The Millipede concept. Operational. Practical, Technological aspects & Manufacturing. Usage Scenarios. Commercial aspects & Conclusion. Research areas & Future challenges References.

MILLIPEDE MEMORY INTRO :

‘Millipede’ is a non-volatile computer memory storage device. Data density > 1 terabit per square inch. 'Millipede' technology is re-writeable. Developed at IBM’s Zurich research laboratory by a team that includes

Gerd Binnig (inventor of the AFM) and engineer Peter Vettiger. IBM demonstrated a prototype at CeBIT, Germany 2005. Replacement for magnetic recording in hard drives. Operational at Low power. Parallel cantilevers to achieve high data rate upto GBps.

THE MILLIPEDE CONCEPT:

Memory is stored on nanoscopic pits burned onto polymer-layer, read and written by a MEMS-based probe.

Bit-wise memory storage.

OPERATIONAL:

Core components of probe storage system:Two-dimensional array of silicon

probes (cantilevers)Micro-mechanical scanner which

moves the storage medium relative to the array.

OPERATIONAL: Memory written in bit-wise corresponding to

spatial co-ordinates. Writing is done by heating the cantilever to

400˚C & making an indentation on the substrate.

Scanning is done at 300˚C by another lever & data depends on the resistance value sensed.

Overwriting can be achieved by many methods. But are limited to 100,000 cycles.

Capacitive platform for electrostatic actuation of the cantilevers in the z-direction.

PRACTICAL & TECH ASPECTS: MANUFACTURING IC: Cantilevers & CMOS are fabricated on

separate wafers both are which are inherently optimized.

Cantilevers are transferred onto the CMOS wafer, using a soldering process that provides a mechanical and electrical interconnect to the CMOS wafer.

A thin film of a custom designed cross-linked polymer coated on a silicon substrate, which is moved in the x-y directions. The storage medium is positioned with nanometre-scale accuracy relative to the cantilever array.

PRACTICAL & TECH ASPECTS: MANUFACTURING The crux of the system is a 2D array of V-

shaped silicon cantilevers that are 0.5 micrometers thick and 70 micrometers long.

Recent array design consists of an array of 64 × 64 cantilevers (4096) on a 100 µm pitch at 100mW allowing data to be written at extremely high densities >1 Tb/in² at an error rate < 1e-4.

The 6.4 × 6.4 mm² array is fabricated on a 10 × 10 mm² silicon chip using "transfer and join" technology that allows the direct interconnection of the cantilevers with CMOS electronics .

PRACTICAL & TECH ASPECTS: MICROSCANNER Scan table (6.8 × 6.8 mm²) carries the polymer medium, and a pair

of electromagnetic actuators (X-Y) & are supported by silicon springs (10–12 µm wide & 400 µm thick) & fabricated on a silicon wafer using a deep trench etching process.

Scanner chip is mounted on a silicon base plate, which acts as the mechanical ground of the system and provides a clearance ~20 µm between top-bottom of the moving parts of the scanner.

Each actuator consists of a pair of permanent magnets mounted in a silicon frame, with a miniature coil mounted between them on the base plate.

The actuator motion is coupled to the scan table using a pivot and a mass-balancing scheme, which makes the system robust against external vibrations and shock.

PRACTICAL & TECH ASPECTS: POSITION SENSING

A fraction of this heat is conducted through the ambient air into the scan table, which acts as a heat sink. Displacement of the scan table gives rise to a change in the efficiency of this cooling mechanism, resulting in a change in the temperature of the heater and thus a change in its electrical resistance.

Accuracy : Sensors provide an effectively linear position signal over the entire 120 µm range of the scanner, with a resolution of less than 2 nm in a 10 kHz bandwidth.

USAGE SCENARIOS: Micro Data Drives Millipede systems can be used for micro drives,

which will feature very small form factor, enabling use in small footprint/wearable devices like watches, mobiles, especially in the Internet of Things, and at the same time provide high capacity. 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, probably, high reliability. These features make them candidates for building high capacity hard drives, with storage capacity in the range of terabytes. Although the data density of a Millipede is high, the capacity of an individual device is expected to be relatively low -- on the order of single gigabytes.

COMMERCIAL ASPECTS & CONCLUSION:

MERITS : High density > 1Tbits/inch² Compact & reliable. Large storage space Possibility of reading ,writing

and overwriting in parallel.

DEMERITS : Expensive As of 2016, Competing

technologies have surpassed this record.

Practical limitations in further upgradation.

Exploring novel methods for writing, reading and erasing data in thermomechanical probe recording.

Research is pursued in the areas of coding, signal processing and read channel design.

Limiting factor in the areal density that can potentially be reached in thermomechanical probe storage is the intrinsic nonlinear interaction between closely packed indentations.

Upon this realization, the storage capacity can be increased by applying (d, k)-constrained codes, similar to the ones used in optical disc recording. The d-constraint in particular is instrumental in limiting the interference between successive indentations as well as in increasing the effective areal density of the storage device.

Continuous advancements on probe-tip fabrication, storage medium design, and improvements on the writing process and on the read channel design has lead to the repeated realization of storage of large amounts of data at densities higher than 1.0 Tb/in² and reliable retrieval of the data at raw error rates better than 1E-4.At these error-rate levels, conventional error-correcting codes (ECC) can successfully correct all errors, & there will be no loss of user data.

RESEARCH AREAS:

DEFERENCE TO THE REFERENCES Wikipedia: https://en.wikipedia.org/wiki/Millipede_memory IBM : http://ethw.org/IBMs_Millipede_Memory_Chip &

Crazyengineers.com Google for providing relevant images & links to resources quickly

& Etc..

Thank You By:HARSHA HN.USN: 1MS12EC042.Dated 30th Jan’16MSRIT, B’lore.