MICROELECTROMECHANICAL SYSTEMS

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WHAT IS MEMS?
Submicron manufacturing promises to
provide economic solutions to meeting
increasingly demanding customer needs and, at the same time, decreasing time to market,energy consumption, and environmental costs. Manufacturing at the submicron level has four evolutionary advances in (1) miniaturization and (2) microelectromechanical systems (MEMS), as well as revolutionary advances in (3) nanofabrication and (4) biotechnology. This paper deals with MEMS.
MEMS SCAN ENGINE (1)
The proliferation of more powerful, but smaller intelligent systems will lead to advances that will be crucial for meeting several of the grand challenges for manufacturing in 2020. Using the fabrication techniques and materials of microelectronics as a basis, MEMS processes construct both mechanical and electrical components. Mechanical components in MEMS, like transistors in Microelectronics, have dimensions that are measured in microns and numbers measured from a few to millions. Ceramics and polymers are becoming important materials for MEMS application because of wide range of properties and promised improvement in performance. MEMS is a fabrication approach that conveys the advantages of miniaturization, multiple components, and microelectronics to the design and construction of integrated electromechanical systems. Following graph shows rapid growth in MEMS market in recent years –
Following graph-

HISTORICAL BACKGROUND OF MEMS TECHNOLOGY:
1960: Invention of planar batch fabrication process improving reliability and cost of semiconductor devices and allowing integration of multiple semiconductor devices.
1970: Development of the microprocessor.
1970s & 1980s: MEMS technology for producing parts for automotive industry.
1989: Researchers at MIT developed the first electro statically controlled
micro motors that used rotating bearing surfaces.
1990s: A tremendous increase in the number of devices, technologies, and
applications has greatly expanded the sphere of influence of MEMS and it is
continuing today.

MANUFACTURING PROCESS
Many of the micro fabrication techniques and materials used to produce MEMS have been borrowed from the IC industry. There are six basic manufacturing steps towards making a final MEMS component.

A) CRYSTAL GROWING
For making high quality, defect free single crystal SPEED SHAFT
material for micro devices silicon has to be purified. The most widely used crystal SPEED CRYSTAL growing method is Czochralski process, (as shown aside). MOLTEN SILICON
It utilizes a seed crystal that is dipped into a silicon —»TO VACCUM PUMP
melt and then slowly pulled out by being rotated. Initially the pulling rate is rapid, which causes the
single crystal of silicon to solidify against the seed, forming a neck. The velocity is then reduced( 10 μm/s), causing the neck to grow into the desired diameter ( usually 50-200mm diameter and 1 m in length), while maintaining the single crystal structure