“MEMS Technology”

Presented By-Dhaval Kaneria (13014061010)

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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 micromachining technology.

• If semiconductor microfabrication was seen to be the first micro manufacturing revolution, MEMS is the second revolution.

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Fabrication Techniques

• Silicon Micro Fabrication

The two most general methods of MEMS integration are:1) Surface micromachining 2) Bulk micromachining

• Non-Silicon Micro fabrication: 1) LIGA

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Surface Micromachining

• 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

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Advantages of surface micro machining

 

a) Structures, especially thicknesses, can be smaller than 10 µm in size,

b) The micro machined device footprint can often be much smaller than bulk wet-etched devices,

c) It is easier to integrate electronics below surface micro-structures, and

d) Surface microstructures generally have superior tolerance compared to bulk wet-etched devices.

The primary disadvantage is the fragility of surface microstructures to handling, particulates and condensation during manufacturing.

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Bulk Micromachining• 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

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LIGA

• 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.

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Continue..

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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

substrate, • Lithography-to apply a patterned mask on top of the films by

photolithograpic imaging.• Etching-to etch the films selectively to the mask. A MEMS process is

usually a structured sequence of these operations to form actual devices.

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Continue..

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Packaging

• As with micromachining processes, many MEMS sensor-packaging techniques are the same as, or derived from, those used in the semiconductor industry.

• 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 sensor3) 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.

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Application Of MEMS

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THE FUTURE OF MEMS TECHNOLOGY

Industry Challenges

• Access to Foundries• Design, Simulation and Modelling• Packaging and Testing• Standardization• Education and Training

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Conclusion.

• 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 environment.

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References.

1. Microsensors, Muller, R.S., Howe, R.T., Senturia, S.D., Smith, R.L., and 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(http://www.ieee.org/pub_preview/mems_toc.html)

4. Journal of Micromechanics and Microengineering(http://www.iop.org/Journals/jm)

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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.

Thank-You

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