MEMS BASED INTEGRATED CIRCUIT

MASS STORAGE SYSTEMS

Presented by

prashant singh(imi2011003)

Highlights New secondary storage technology that could revolutionize computer

architecture.

-Faster than hard drives

-Lower entry cost

-Lower weight and volume

-Lower power consumption

Discuss physical description of device.

Disk Drive limitations Disk-drive capacities double every 18 months

-better 60% per year growth rate of semiconductor memories

Two major limitations of disk drives are…..

-Access times decreases have been minimal

-Minimum entry cost remains too high for many applications

Problem Specification

Requirement of mass storage system that can break both barrier

-Access times

-Minimum entry cost

New mass storage should also be significantly cheaper than non-volatile RAM

-$100 now buys 1 GB of flash memory

MEMS MEMS use

-Same parallel wafer-fabrication process as semiconductor memories

-Keeps the prices low

-Same mechanical positioning of R/W heads as disk drives

-Data can be stored using higher density thin film technology

Main Advantages Of MEMS

Potential for dramatic decrease in-Entry cost(10x cheaper than RAM)

-Access time

-Volume

-Mass

-Power dissipation

-Failure rate

-Shock sensitivity

Integrate storage with computation

-Complete system-on-chip integration

-Processing unit

-RAM

-Non-volatile storage

MEMS storage prototype

Like a disk drive, it has

-recording heads

-a moving magnetic recording medium

Major departures from disk drive architecture are

-MEMS recording heads-probe tips-are fabricated in a parallel wafer level manufacturing process

-Media surface does not rotate(Data latency decreases)

Data Organization

disk

MEMS

Media Surface Movement

Media surface that rotate requires ball bearings

Very small ball bearing may have “striction” problem that prevent accurate positioning

-Element would move by sticking and slipping

Best solution is to have media sled moving in X-Y directions

-Sled moves in Y-direction for data access

-Sled is suspended by spring

Read/writetips

Read/writetips

Conceptual View of “Moving Media”(CMU prototype)

Read/Writetips

Read/Writetips

MagneticMedia

MagneticMedia

ActuatorsActuators

Bits storedunderneath

each tip

Bits storedunderneath

each tipMediaMedia

side view

SpringsSprings

Operation (A) (B) (C)

(D) (E) (F)

The Media Sled

Actuator pull sled in both dimensions

Size 8mm X 8mm X 500µm

Held over the probe tip array by a network of springs

Motion applied through electrostatic actuators

-Motion limited to 10% or less of suspension/actuator length

-Each probe tip can sweep 1% of the media sled

Include large number of probe tips for

-Improving data throughput

-Increasing system reliabilityRead write operation

Probe Tip Positioning Most MEMS include some form of tip height control because

-Media surface is not perfectly flat

-Probe tip height may vary

CMU(Carnegie Mellon University,Pennsylvania,US) prototype places each probe tip on a separate cantilever

-Cantilever is electrostatically actuated to a fixed distance from the media surface

IBM Millipede

-Uses 32 x 32 array of probe tips

-Each tip is placed at the end of a flexible cantilever

-Cantilever bends when tip touches surface

HP design places media surface and probe tips sufficiently apart

-No need to control probe tips heightIBM Millipede

Probe Tip Fabrication Major challenge is fabricating read/write probe tips in a way that is

compatible with the underlying CMOS circuitry

This includes

-thermal compatibility

-geometrical compatibility

-chemical compatibility……..

Failure Management MEMS devices will have internal failures

-Tips will break during fabrication/assembly, use

-Media can wear(erosion/sideways displacement)

Storing, Reading and Writing Bits CMU prototype uses same magnetic recording technology as current

disk drives

-Minimum mark size around 80µm x 80µm

Other solutions include

-Melting pits in a polymer (IBM Millipede)

-Raises tip wear issues

Potential Application Lighter and less shock sensitive than disk drives

-Great for notebook PC’s,PDA’s and video camcorders

Lower cost than disk drives in 1 to 10 GB range

-Will open many new applications

High areal densities

-Great for storing huge amounts of data

Can combine computing and storage on a single chip

E.g. Average service time around 0.52 ms

-Disk drive service time is 10.1 ms

-Key factor for service time is X-seek time

Thank You