1. MEMS BASED
INTEGRATED CIRCUIT
MASS STORAGE SYSTEMS
Presented by
prashant singh
(imi2011003)

2. 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.

3. 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

4. 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

5. 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

6. 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

7. 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)

8. Data Organization
disk
MEMS

9. 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

10. Conceptual View of “Moving Media”(CMU prototype)
Read/Write Read/write
Actuators tips tips
Springs
Magnetic
Media
Bits stored
Media underneath
side view each tip

11. Operation
(A) (B) (C)
(D) (E) (F)

12. 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 reliability
Read write operation

13. 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 IBM Millipede
-No need to control probe tips height

14. 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……..

15. Failure Management
MEMS devices will have internal failures
-Tips will break during fabrication/assembly, use
-Media can wear(erosion/sideways displacement)

16. 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

17. 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

18. Thank You