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A science that combines electronics, life science,
mechanical engineering, and industrial applications, the MEMS
technology, through bound by cross-domain support, non-standardized
fabrication technology, mechanical characteristics and an integrated
design, has a great potential of evolving from a substitution
into one that yields innovation, with estimated potential yield
exceeding US$40 billion in 2003, that goes beyond the more conventional
applications of inkjet printer head, disk driver retriever head,
hearing aid,pressure sensor, and is expected to move in on emerging
science in the applications of information technology, biotechnology
and Nanome technology. |
Among them, the biomedical domain and the miscellaneous engineering
domain have come to provide an emerging concept for the new millennium,
as cross-domain integration would infinitely become more important
and perfected to serve as a vital key in kicking off the next round
of industry leap in Taiwan.
| Taking to the application of the
micro-flow metering system in biomedical chipset, the MEMS technology
is poised to revolutionize new drug research, genetic engineering,
environmental surveillance, as well as clinical prognosis. The
adaptation of the MEMS technology not only helps to scale down
the bulky biomedical instruments but can also integrate its
functions in culture sampling, transmission, reaction, separation
and detection into a lab-on-a-chip format. The implication implies
that it not only excel the checkup rate but also reduces checkup
cost with greatly reduced timing and culture sampling. |
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More than serving to streamline a varied conventional functional structure
into one comprehensive system, MEMS also helps to enhance system performance
and dependability thanks to its advantages of compactness and supporting
mass production when applied to semiconductor process. Its other advantages
include substantially cutting down the sampling and timing in calibration,
offering a swift, parallel validation, as well as lowering production
costs.
The adaptation of MEMS in micro flow metering can be grouped roughly
into the followings,
¡]1¡^ Micro flow transmission and control : the integration of micro
switching, micro pump and micro tracks for producing a single unit
intelligent micro flow chipset.
¡]2¡^ Microchemistry analysis system : means to rapid DNA separation
using microelectrode chipsets and cellular separation.
¡]3¡^ Biomedical screenings : such as the micro blood analyzer, auto
renal discharge tracks, micro metering drug conveyance system.
¡]4¡^ Micro flow metering control : means to produce precision metering
and control of process gas flow.
| In medical applications, more than its compactness, the concern
for secondary pollution has also spawned the necessity of developing
low-cost disposable micro flow biomedical chipsets. For instance,
inexpensive biomedical chipsets can be produced using the straightforward
and highly dependable MEMS process for commercial optical shield,
taking to approx. 1£gm optical shield and approx. 01.£gm of chromium
layer on top of an approx. 2.3mm quartz substrate before bonding
them and transposing the template onto a PMMA material, with
injection track and branch measuring approx. 6mm and 30mm, and
a trench depth and width at 40£gm and 100£gm, respectively. While
the compression technique allows the formation of uniformed
micro liquid flow plastic chipset, which not only poises to
improve the rate of analysis, but the chipset's having already
treated with protein suppressant also provides a vital yield
in clinical prognosis as it can be applied to protein analysis
without requiring pre-treatment. |
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In response to the MEMS development and application trend, AST has
since launched a series of exclusive MEMS process equipment, which
consist of ICP-RIE equipment, PECVD
equipment, Sputter equipment, E-Beam
Evaporator equipment and the like, all are intended to enhance
the local MEMS processing industry with an extra competitive edge.
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In general, with its fabrication taking to physical
micro process and surface micro process, there could be substantial
disparity in micro structure and surface characteristics among
the two major materials groups used for fabricating silica wafer
MEMS sensor components in that there is more than the dimensional
variations but also varied dimensions in structural material
and varied processes in MEMS processes. Or even varied MEMS
processes could lead to significant disparity arisen from a
materials electrical property and mechanical property. For instance,
there are distinguishable differences on the synthesis of an
identical material using the PECVD
and SiO2 processes in terms of their eventual dielectric, mechanical
strength and residual stress are concerned. |
Below provides an in-depth account on plasma process equipment and
related processes, including the inductively coupled plasma reactive
ion etching (ICP-RIE process) and the plasma-enhanced
chemical vapor deposition SiC PECVD process
equipment.
First, the technical development of the Inductively Coupled Plasma
Reactive Ion Etching (ICP-RIE)centers around
adopting a surface process design via a physical process, in which
tow alternative work cycles are incorporated to etch and insulate
the surface. While C4F8 is used to seal the sides to present sideway
etching, SF6 is then used for nonlinear etching in a repetitive manner,
hence be able to etch out several hundred micrometers in depth at
an equivalent height-width ratio in a matter of hours
In addition, how the MEMS system provides a greater application potential
in more stringent settings in that the current standard material of
Si has not been truly ideal to apply in heat and chemically volatile
setting also puts the application of MEMS ever more important in terms
of locating suitable alternative materials. Of which, SiC, a highly
inert material against reactionary volatility and at a higher energy
scale than Si alone, also makes it suitable in power electronics applications,
and has a significant development potential in the mechanical and
electrical fields.
| Although a lower production means using PECVD
PECVD for fabricating SiC membrane, in which plasma-enhanced
reactionary dispersion allows such chemical process be conducted
at low temperature, a major hindrance arisen from substantial
internal stress due to a low surface diffusion created at low
temperature to lead to cracking as the thickness of SiC deposition
membrane becomes excessive (50 ~ 60£gm) would have to be overcome.
As to SiC surface bonding process, it can be obtain through
incorporating a reverse target defined for an Si substrate on
an ICP-RIE equipment, together with
a PECVD equipment that deposits SiC
on the silica target before finally having the etching liquid
rinsed off. |
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