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This technology was evolved from Micro-electronics revolution and extensively

used in manufacturing various devices, such as pressure sensors, accelerometers, flow

sensors, inkjet printers, deformable mirror devices, gas sensors, micro-motors, and

micro-gears. In recent times the market growth and demand for MEMS is increasing

at a rapid rate due to wide range of applications in designing various military, civil

and bio-applications. They are critically used in Integrated Circuit (IC) technology,

mechanical, chemical and electrical engineering, material science and fabrication

technology [1].

MEMS technology is having its impact on Microwave Communication Systems,

Phased Array Beam former, EW Transmitters and Space based Radar Systems. All

the above systems use switches, which are limited by insertion losses. At present

most commonly used switch devices are PIN diodes, GaAs FETs and Conventional

mechanical Switches.

MEMS are preferred as they can realize similar to Very Large Scale Integration

(VLSI) process technology, which is well established. The fabricated structures can

be integrated with MMICs (Monolithic Microwave Integrated Circuit) as well as

VLSI circuits. The fabricated structures have good mechanical properties as well as

good electrical performance like:

• Very good isolation and low insertion losses.

• Low circuit power consumption in either ON or OFF state.

• Switching speed is sufficient for control; and

• Reliable Systems.

Background of MEMS

The studies on MEMS are being carried out since 1960s and first device appeared

in 1970s. However, a boost from public interest allowed this technology get funding

from various government agencies [2]. In 21st Century, MEMS are considered to be

the most promising technologies to revolutionize industrial and consumer products

by using Si based microelectronics and machining technologies. They consist of

mechanical micro-structures, micro-sensors, micro-actuators and micro-electronics

integrated on a Silicon chip. The devices designed using MEMS are very small and

components are microscopic. However, many components like levers, gears, pistons,

small motors and even steam engines are fabricated using MEMS.

Ingeneral,thetermMEMSisalsoreferredtobeMicroSystemTechnology(MST),

but sometimes it is also considered to be a subset of MST as it deals with the creation

of tiny mechanical devices or systems. Apart from this MOEMS (Micro-opto-electro-

mechanical Systems) are also considered to be the subset of MST (Fig. 11.1).

The terms transducer, sensor and actuator are mostly used terms in MEMS

technology and they are defined as follows:

Transducer: It is a device that transforms one form of signal or energy to other

form. It is generally used with both sensors and actuators.