Biomedical Engineering Reference
In-Depth Information
to equal those of ICs. Yet, even though the performance of MEMS and nano
devices is expected to be superior to macroscale components and systems,
the price is predicted to be much lower.
MEMS technology is based on a number of tools and methodologies,
which are used to form small structures with dimensions in the micrometer
scale (one millionth of a meter). Significant parts of the technology have been
adopted from IC technology. For instance, almost all devices are built on
wafers of silicon, like ICs. The structures are realized in thin films of materi-
als, like ICs. They are patterned using photolithographic methods, like ICs.
There are however several processes that are not derived from IC technology,
and as the technology continues to grow the gap with IC technology also
grows.
There are three basic building blocks in MEMS technology, which are the
ability to deposit thin films of material on a substrate, to apply a patterned
mask on top of the films by photolithograpic imaging, and to etch the films
selectively to the mask. A MEMS process is usually a structured sequence of
these operations to form actual devices.
7.2.6 Developments Needed
MEMS and nanotechnology are currently used in low- or medium-volume
applications.
Some of the obstacles preventing its wider adoption are the following.
7.2.6.1 Limited Options
Most companies who explore the potential of MEMS and nanotechnology
have very limited options for prototyping or manufacturing devices and
have no capability or expertise in microfabrication technology. Few compa-
nies will build their own fabrication facilities because of the high cost. A
mechanism giving smaller organizations responsive and affordable access
to MEMS and Nano fabrication is essential.
7.2.6.2 Packaging
The packaging of MEMS devices and systems needs to improve considerably
from its current primitive state. MEMS packaging is more challenging than
IC packaging due to the diversity of MEMS devices and the requirement
that many of these devices be in contact with their environment. Currently,
almost all MEMS and nano development efforts must develop a new and spe-
cialized package for each new device. Most companies find that packaging is
the single most expensive and time-consuming task in their overall product
development program. As for the components themselves, numerical mod-
eling and simulation tools for MEMS packaging are virtually nonexistent.
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