MEMSMicro-Electro-Mechanical Systems

By:-Vikas poonia

(2013btec001L)

What is MEMS?Micro-Electro-Mechanical

Systems◦ is the integration of elements, sensors, actuators,

and electronics on a common silicon substrate through micro-fabrication technology, a manufacturing technology for making microscopic devices

◦Other Materials used in MEMS Gallium Arsinide Titanium Nickel Piezoelectric Materials

Micro Electro Mechanical Systems

Electrical sensing/actuation◦ Capacitive◦ Piezoelectric◦ Piezoresistive

Mechanical devices with a third dimension

Systems◦ Multiple functions on one

piece of silicon IMD

AMFitzgerald

AMFitzgerald

Size of MEMS

Birth of MEMS1970’s: using silicon

processing to make mechanical devices, not transistors◦Accelerometers◦Pressure sensors◦Inkjet nozzles

1982: Petersen’s “Silicon as a Mechanical Material”

Popular Science, June 1984

How MEMS are made! There are three main building blocks

in MEMS Deposition process

The ability to deposit thin films of material

Lithography is typically the transfer of a

pattern to a photosensitive material by selective exposure to a radiation source such as light

Etching Process Wet etching where the material

is dissolved when immersed in a chemical solution

Dry etching where the material is sputtered or dissolved using reactive ions or a vapor phase etchant

MEMS is a miniaturization technology

Airbag sensors (1980) Airbag sensors (2005)

MEMS belong where miniaturization is neededApplications using MEMS devices:

◦ Automotive: pressure, motion, sound, light, heat

◦ Consumer: motion, sound, pressure, compass

◦ RF: filters, resonators, switches, inductors◦ Optical: network components, displays,

switches, mirrors◦ Medical devices: needles, cell scaffolds,

ultrasound, implantables◦ Printing: inkjet, large format nozzles◦ Biotech: lab-on-chip microfluidics◦ Industrial: Atomic force microscopy,

chemical sensors

Smaller, better, cheaper◦ But not always all three!

Sophisticated capabilities in small form factor:◦ Multiple sensors◦ Signal processing and

analysis◦ Telemetry capability◦ Low power

Why MEMS are exciting for so many applications

Integrated Pressure

Sensor

MEMS sensor

Stacked MEMS and ASIC chips,

wirebonded

Applications of MEMS

• MEMS-based sensors are a crucial component in automotive electronics, medical equipment, smart portable electronics such as cell phones.

• PDAs, and hard disk drives, computer peripherals, and wireless devices.

• These sensors began in the automotive industry especially for crash detection in airbag systems.

Explosion of MEMS in consumer devices

Sophisticated capability in small form factor enabling new functions◦Motion sensing -> gesture input,

navigation◦Microphone arrays -> noise

cancellation◦Pressure sensing -> height detection

At the right price!◦MEMS took off when chip price <$3

MEMS enable exciting new products

MEMS are not like ICsYes, both are made on silicon wafersNo building block technology, i.e. no

transistor◦Moore’s law does not apply◦No standardization of design,

processes, or materials◦Each MEMS is custom-crafted

“One product, one process, one package”

What this impliesMEMS prices will not decrease as

fast as IC chips didMEMS sensor performance will

not improve as fast as microprocessors, memory chips did

Chip packaging usually critical to MEMS performance

System integration can be more challenging

ExpectedCharacteristics of MEMSIn the future, MEMS

Technology compared to Conventional Technology should have these effects:◦ Cost reduction◦ Increase functionality◦ Improve reliability◦ Decrease size◦ Decrease mass

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