|
What is MEMS technology?
..................................................................................................................................
 Micro-Electro-Mechanical
Systems (MEMS) is the integration of mechanical elements, sensors,
actuators, and electronics on a common silicon substrate through
microfabrication technology. While the electronics are fabricated
using integrated circuit (IC) process sequences (e.g., CMOS, Bipolar,
or BICMOS processes), the micromechanical components are fabricated
using compatible "micromachining" processes that
selectively etch away parts of the silicon wafer or add new
structural layers to form the mechanical and electromechanical
devices.
MEMS promises to revolutionize nearly every product category by bringing
together silicon-based microelectronics with micromachining
technology, making possible the realization of complete
systems-on-a-chip. MEMS is an enabling technology allowing the
development of smart products, augmenting the computational ability of
microelectronics with the perception and control capabilities of
microsensors and microactuators and expanding the space of possible
designs and applications.
Microelectronic integrated circuits can be thought of as the
"brains" of a system and MEMS augments this decision-making
capability with "eyes" and "arms", to allow
microsystems to sense and control the environment. Sensors gather
information from the environment through measuring mechanical,
thermal, biological, chemical, optical, and magnetic phenomena. The
electronics then process the information derived from the sensors and
through some decision making capability direct the actuators to
respond by moving, positioning, regulating, pumping, and filtering,
thereby controlling the environment for some desired outcome or
purpose. Because MEMS devices are manufactured using batch
fabrication techniques similar to those used for integrated circuits,
unprecedented levels of functionality, reliability, and
sophistication can be placed on a small silicon chip at a relatively
low cost.
The following tips were compiled based on our
experience with various MEMS product development programs.
●Each MEMS foundry has its own technologies
and processes that make up its core competencies. Partnering with a
foundry that has a rich history in producing the type of device and
features desired will shorten development timelines and increase the
quality of both initial prototypes and low volume manufacturing.
●Design for test and packaging. Testing, QA
(Quality Assurance) and packaging issues often incur the largest
portion of fabrication expenses. These issues are often ignored
during the early stages of product development; addressing them up
front will reduce both development and ongoing fabrication costs.
●Run tolerance tests to find out what
specifications are absolutely paramount and what specifications can
be relaxed. An over-specified device will be needlessly expensive to
produce.
●Bring the foundry into the design process
as early as possible. The earlier a foundry is involved, the easier
it is to create a manufacturable design.
●Be clear and specific about requirements.
Keep engineering as simple as possible and do not be afraid to ask
for what is wanted. If the question is not asked, it may not be
answered.
●Do not underestimate the time and expense
required to develop a stable design and process. Unlike cases in the
fabless semiconductor industry, it may take more than a single run
for a product to meet expected specifications. Usually a foundry
undertakes a combination of short loop experiments, engineering runs,
and small pilot runs before transferring products to manufacturing.
●Plan to succeed. In consultation with a
foundry, a MEMS product company has to set achievable goals in terms
of price, delivery time, and/or quality. Getting input early from a
foundry will allow for more realistic budgets and timelines to be
prepared for internal planning and for securing financing
commitments.
●Design for manufacturability. As much as possible,
use standard known microfabrication process steps with achievable
tolerances. If a foundry needs to develop several new process steps,
it will result in higher development costs and lower yields during
initial manufacturing. At the same time, the onus is on the foundry
to supply well-characterized, repeatable and reliable processes to
its customers.
●Determine whether the device can be
transferred into commercial production. A complex MEMS device that
represents a novel technical solution may be very difficult or too
costly to manufacture at a high volumes.
|
