Introduction of MEMS
• MEMS means micro electro mechanical systems
• MEMS, often referred to as micro systems technology, are fabricated using
modified silicon and non-silicon fabrication technology.
• MEMS is a process technology used to create tiny integrated devices or
systems that combine mechanical and electrical components.
• These devices (or systems) have the ability to sense, control and actuate
on the micro scale, and generate effects on the macro scale.
• MEMS has been identified as one of the most promising technologies for
the 21st Century and has the potential to revolutionize both industrial and
consumer products by combining silicon based microelectronics with
• If semiconductor microfabrication was seen to be the first micro
manufacturing revolution, MEMS is the second revolution.
• Silicon Micro Fabrication
The two most general methods of MEMS integration are:
1) Surface micromachining
2) Bulk micromachining
• Non-Silicon Micro fabrication:
• Surface micromachining enables the fabrication of complex
multicomponent integrated micromechanical structures that would not be
possible with traditional bulk micromachining.
• One of the most important processing steps that is required of dynamic
MEMS devices is the selective removal of an underlying film, referred to as
a sacrificial layer, without attacking an overlaying film, referred to as the
structural layer, used to create the mechanical parts
Advantages of surface micro machining
thicknesses, can be smaller than 10 µm in size,
The micro machined device footprint
can often be much smaller than bulk wet-etched
It is easier to integrate electronics
below surface micro-structures, and
Surface microstructures generally
have superior tolerance compared to bulk wetetched devices.
The primary disadvantage is the fragility of
handling, particulates and condensation during
• Bulk micromachining is an extension of IC technology for the fabrication of
3D structures. Bulk micromachining of Si uses wet- and dry-etching
techniques in conjunction with etch masks and etch stops to sculpt
micromechanical devices from the Si substrate.
• Two additional processing techniques have extended the range of
traditional bulk micromachining technology: deep anisotropic dry etching
and wafer bonding. Reactive gas plasmas can perform deep anisotropic
dry etching of Si wafers, up to a depth of a few hundred microns, while
maintaining smooth vertical sidewall profiles. The other technology, wafer
bonding, permits a Si substrate to be attached to another
substrate, typically Si or glass
LIGA is a German acronym standing for lithographie, galvanoformung
(plating), and abformung (molding).
• However, in practice LIGA essentially stands for a process that combines
extremely thick-film resists (often >1 mm) and x-ray lithography, which can
pattern thick resists with high fidelity and results in vertical sidewalls.
• The LIGA process exposes PMMA (poly methyl metha crylate) plastic with
synchrotron radiation through a mask.
MEMS DESIGN PROCESS
• There are three basic building blocks in MEMS technology, which are,
• Deposition Process-the ability to deposit thin films of material on a
• Lithography-to apply a patterned mask on top of the films by
• Etching-to etch the films selectively to the mask. A MEMS process is
usually a structured sequence of these operations to form actual devices.
• As with micromachining processes, many MEMS sensor-packaging
techniques are the same as, or derived from, those used in the
• Microelectronic packages are often generic with plastic, ceramic, or metal
packages being suitable for the vast majority of IC applications.
• A MEMS sensor packaging must meet several requirements :
1) Protect the sensor from external influences and environmental effects.
2) Protect the environment from the presence of the sensor
3) Provide a controlled electrical, thermal, mechanical, and/or optical
interface between the sensor, its associated components, and its
environment. Not only must the package protect both the sensor and its
environment, it must also provide a reliable and repeatable interface for all
the coupling requirements of a particular application.
THE FUTURE OF MEMS TECHNOLOGY
Access to Foundries
Design, Simulation and Modelling
Packaging and Testing
Education and Training
• The automotive industry, motivated by the need for more efficient safety
systems and the desire for enhanced performance, is the largest consumer
of MEMS-based technology.
• In this seminar I explained all basic parameter and techniques which is
required for further research and product development.
• MEMS will be the indispensable factor for advancing technology in the
21st century and it promises to create entirely new categories of products.
• Medical applications include the detection of DNA sequences and
metabolites. MEMS biosensors can also monitor several chemicals
simultaneously, making them perfect for detecting toxins in the
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White, R.M. [Eds.], IEEE Press, New York, NY, 1991.
2. Micromechanics and MEMS: Classic and Seminal Paper to
1990, Trimmer, W.S., IEEE Press, New York, NY, 1997.
3. Journal of Microelectromechanical Systems
4. Journal of Micromechanics and Microengineering
5. Berkeley Sensor and Actuator Center, http://bsac.eecs.berkeley.edu
6. University of Stanford, http://www.stanford.edu/group/SML/ee321/ho/MEMS-01-intro.pdf
7. Trimmer, W.S., Micromechanics and MEMS: Classic and Seminal Papers to 1990, IEEE
Press, New York, NY, 1997.
8. Tjerkstra, R. W., de Boer, M., Berenschot, E., Gardeniers, J.G.E., van der Berg, A., and
Elwenspoek, M., Etching Technology for Microchannels, Proceedings of the 10th Annual Workshop
of Micro Electro Mechanical Systems (MEMS ’97), Nagoya, Japan, Jan. 26-30, 1997, pp. 396-398.