Mems

MEMS MICROELCETROMECHANICALSYSTEMS

GUIDE Mr. DEEPAK N.A.

TECHNICAL SEMINAR E. RAM KUMAR (1BY05EC015)

Agenda  History  Definition  Overview  Applications  Futures  Conclusion

Microelectronics- Historical Perspective  Point contact Transistor invented in 1947 by Bardeen, Brattain, Schokly at Bell Telephone laboratory.  Nobel Prize in 1956  Oxidation demonstrated in 1953 at Bell Telephone Laboratory

Microelectronics- Historical Perspective

 Jack S. Kilby invented Monolithic Integrated Circuit in 1958.  US Patent Filed on Feb 6th,1959. U.S. Patent #3138743  Noble Prize in 2000

Microelectronics- Historical Perspective

 IC’s in early 1960s with for BJTs and several Resistive elements.

 IC’s in early 1990s with over 1million Transistors (MOS).

Silicon ICs Status And Trends

Silicon ICs Status And Trends



MOORE’S LAW: The number of transistors that can be placed inexpensively on an integrated circuit has increased exponentially, doubling approximately every two years.

Silicon Microelectronics  Silicon Wafer size (~4 – 12 inches)  Silicon chip size (~2 inches)  Currently>100M transistors/chip  Projection in 2014: 20B transistors/chip

Size does matters…

What are MEMS?  Micro

- Small size, microfabricated structures

 Electro

- Electrical signal/control

 Mechanical

- Mechanical functionality

 Systems

- Structures, Devices, systems - Control

Cont... 

   

Integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through micro fabrication technology. Components between 1 to 100 micrometers in size (i.e. 0.001 to 0.1 mm). They are fabricated by Batch processing techniques to sense, control and actuate on micro scale. Micromachining techniques were adapted for precision of structures from micrometers to nanometers MEMS can transform whole of electronics and mechanical devices to micro scale.

Multidisciplinary Micro-Probing (STM,AFM) Micro-optics Micro-Fluids

Bio-MEMS

Micro-Scale Actuation and Motion

MEMS

RF-MEMS

Pressure, Force, Inertia, sound etc

Micro- magnetics

History of MEMS technology 

Richard Feynman- “There’s plenty of room at the bottom” - Presentation given at California Institute Of technology, 26th Dec 1959. -Tries to spur innovative miniature fabrication techniques for micromechanics



Westinghouse creates the “Resonant Gate FET” in 1969.

 

Bulk-etched silicon wafers used as pressure sensors in 1970s. Early surface micromachined polysilicon in 1980s.



Micromachining leverages and microelectronics industries in late 1990s.

Micromachining   

Process to remove excess or unwanted stock by the use of machine tools. Micromachining techniques were originally developed for IC indusrty(1960s). Micromachining distinguish: 1. Surface micromachining: use deposited thin films. 2. Bulk micromachining: use (silicon) substrate.

Surface micromachining

Bulk micromachining

Scaling 

To design micromechanical actuators, it is helpful to understand how forces scale.



In building small actuating systems, one cannot easily combine small motor, gears or screw together.



Size of a system depends on magnitude of integrations and complexity.



Scaling by a variable S that represents linear scale system.

Water bug   

Weight of water bug scales as volume(S3). Surface tension (S1). Force on bug’s foot(S2).



When scale size decreases, weight decreases rapidly than surface tension.



Changing weight from 2m to 2mm causes a weight decrease a billion factor than the surface tension. Hence, the bug walks on water.

First Aerospace Device

Bi-Directional Micro Thruster Place: Under the Aerospace Corporation, NASAJPL, MIT, and Lewis Research center with in July, 1998. Specifications: Mass flow rate

= 5 x 10-8 kg/s.

Thrust

= 1 mN

Thruster are a gas plenum 1 mm deep by 36 mm2 Commercially available at EG & GIC sensor corp…

Micro Nozzle 1. A supersonic nozzle for space propulsion application. 2. Specification •

Throat diameter = 100 μm

• Expansion range = 10:1 • Length = 1 mm

MEMS Picosat 

The primary goal of picosasts mission is to validate microelectromechanical systems (MEMS) radio frequency switches designed by Rockwell Science Center, Thousand Oaks, Calif.



The two orbiting picosats are to be tethered because they will communicate via micro power radios



The tether contains thin strands of gold wire to facilitate radar tracking by U.S. Space Command. Concepts for the future involve optical communication via fiberoptic tethers and other cluster architectures for miniature satellites for which experience with tethers is useful.



Accelerometer 

These are the devices used to measure acceleration.



These are used for airbag sensors.



MEMS version of accelerometer are miniature in size.



They are low cost, smaller and light in weight.

Goals for Accelerometer Specifications Through experiments we intend to determine: 

Required bandwidth to detect meaningful acceleration.



Analog outputs of accelerometer were used.



Range of accelerations generated from impact and foot slip Required accelerometer sensitivity.

`

Futures MEMS is an enabling technology that will be part of both macro and micro systems. MEMS array can be used to change the geometry of the system. MEMS exploration in space in coming years will emphasize cost effectiveness and exploration of robust, ultra-miniaturized, cost-effective and functionality focused smart air planes. Use of MEMS robot for repairing and house-keeping the main satellite.

Conclusion • Reduction of cost for a given performance. • Extreme miniaturisation possible. • Microtechnology allows production of multiple types of microdevices. • Possibility of enabling new functions. • Improve performance of existing functions. • Shorter development time. • Controlled risk.

Thank you!!!