(1) MEMS-based mass storage devices could revolutionize computer architecture by providing faster access times, lower costs, and smaller sizes than traditional hard disk drives. (2) Proposed MEMS devices would use microscopic probe tips on a movable sled to read and write data on a magnetic storage surface, allowing for faster access and higher densities than rotating disks. (3) Major challenges include fabricating the probe tips to be compatible with CMOS circuits and managing failures, but potential applications include use in devices like laptops, cameras, and systems-on-a-chip due to advantages in speed, size, cost and robustness over disk drives.

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