MEMS
Tutorial
Definition
MEMS stands for Microelectromechanical systems, a manufacturing
technology that enables the development of electromechanical systems
using batch fabrication techniques similar to those used in integrated
circuit (IC) design. MEMS integrate mechanical elements, sensors, actuators
and electronics on a silicon substrate using a process technology called
microfabrication.
This combination of silicon-based microelectronics and micromachining
technology allows the system to gather and process information, decide
on a course of action, as well as control the surrounding environment,
which in turn increases the affordability, functionality and performance
of products using the system. Due to this increase in value, MEMS are
expected to drive the development of "smart" products within
the automobile, scientific, consumer goods, defense and medical industries.
How
MEMS work:
The
sensors gather information by measuring mechanical, thermal, biological,
chemical, magnetic and optical signals from the environment. The microelectronic
ICs act as the decision-making piece of the system, by processing the
information given by the sensors. Finally, the actuators help the system
respond by moving, pumping, filtering or somehow controlling the surrounding
environment to achieve its purpose.
Three
key pieces are used in MEMS development:
Deposition
processes are processes that result in the deposit of thin films on
the substrate. Deposition occurs due to various chemical or physical
reactions and can have many forms. After the films are deposited, they
are locally etched by either lithography or etching processes.
Lithography
is the transfer of a pattern to a photosensitive material by selective
exposure to a radiation source.
Etching
processes are used on the films deposited (mentioned above) to form
the functional MEMS structure. Etching either occurs when a liquid is
added that will dissolve the material (wet etching) or by dry etching,
when the substrate is put into a reactor in order to break the gas molecules
into ions which react with the material being etched.
MEMS
Applications
MEMS have uses within the automobile, scientific, consumer
goods, defense and medical industries. Some examples include:
- Pressure, temperature, chemical and vibration sensors
- Light reflectors
- Switches
- Accelerometers (for airbags, pacemakers and games)
- Microactuators for data storage and read/write heads
- All-optical switches
Applications
of these devices are emerging in a wide variety of industries, such
as automobile (air bag sensor/exploders), healthcare (intravenous blood
pressure monitors), and consumer products (thermisters of all kinds).
MEMS
are also used by DARPA
to improve weapons performance for the US military.
Terms
Sensor - device
that gathers information from its surrounding environment and provides
output variables to a measuring instrument.
Actuator - device
that creates a force to manipulate itself or another mechanical device
to perform some useful function.
Batch fabrication
- mass commodity production, which makes it possible to produce a product
in large volumes with a low cost.
Additional
sources of information*
The
MEMS Exchange
MEMS
Clearinghouse
MEMS
Center
*The WAVE Report is
not responsible for content on additional sites 10/10/01 |
