K-MAC | SPR Analysis, Bio Diagnosis, Thickness Measurement, Miniature Spectrometer

■ What is MEMS?
MEMS is Micro Electro Mechanical System meaning technology for micro semiconductor processing. This technology is to integrate electric and mechanical parts into micro small size one, and MEMS means to fabricate a system with new function by combining mechanical structure and electric structure of micro scale together.

This system technologies are miniaturized systems which comprise sensor, actuators and electronic functions thereby opening up a whole range of new applications which would not be possible with purely microelectronic systems.

MEMS promises to revolutionize nearly every product category by bringing together silicon-based microelectronics with micromachining technology, making possible the realization of complete systems-on-a-chip. MEMS is an enabling technology allowing the development of smart products, augmenting the computational ability of micro electronics with the perception and control capabilities of micro-sensors and micro- actuators and expanding the space of possible designs and applications.
Bio-MEMS is one of the application related to biotechnology such as the Polymerase Chain Reaction (PCR) microsystems for DNA amplification and identification, micromachined Scanning Tunneling Microscopes (STMs), biochips for detection of hazardous chemical and biological agents, and microsystems for high-throughput drug screening and selection.

■ MEMS Benefit
Small size / Lighter / Cheaper
Low Power / High reliability / Icrease levels of integration
Multifunctional enable / Cost effective

■ Thin Film Deposition Process
MEMS deposition technology can be classified in two groups:

1. Depositions that happen because of a chemical reaction:
   - Chemical Vapor Deposition (CVD)
   - Electrodeposition
   - Epitaxy
   - Thermal oxidation

These processes exploit the creation of solid materials directly from chemical reactions in gas and/or liquid compositions or with the substrate material. The solid material is usually not the only product formed by the reaction. Byproducts can include gases, liquids and even other solids.

2. Depositions that happen because of a physical reaction:
   - Physical Vapor Deposition (PVD)
   - Casting

Common for all these processes are that the material deposited is physically moved on to the substrate. In other words, there is no chemical reaction which forms the material on the substrate. This is not completely correct for casting processes, though it is more convenient to think of them that way.

[Gold Thin Film Chip made by E-beam Evaporation for SPR Biosensor]

■ Lithography & Etching Process
MEMS deposition technology can be classified in two groups:

Lithography in the MEMS context is typically the transfer of a pattern to a photosensitive material by selective exposure to a radiation source such as light. A photosensitive material is a material that experiences a change in its physical properties when exposed to a radiation source. If we selectively expose a photosensitive material to radiation (e.g. by masking some of the radiation) the pattern of the radiation on the material is transferred to the material exposed, as the properties of the exposed and unexposed regions differs.
In order to form a functional MEMS structure on a substrate, it is necessary to etch the thin films previously deposited and/or the substrate itself. In general, there are two classes of etching processes:

1. Wet etching where the material is dissolved when immersed in a chemical solution
2. Dry etching where the material is sputtered or dissolved using reactive ions or a vapor phase etchant

[Gold Sensor Chip Patterning Process]

■ Micro Fluidics Chip Fabrication Process

[Gold Sensor Chip Patterning Process]

■ MEMS and Nanotechnology Application

There are numerous possible applications for MEMS and Nanotechnology. As a breakthrough technology, allowing unparalleled synergy between previously unrelated fields such as biology and microelectronics, many new MEMS and Nanotechnology applications will emerge, expanding beyond that which is currently identified or known. Here are a few applications of current interest:

Biotechnology
MEMS and Nanotechnology is enabling new discoveries in science and engineering such as the Polymerase Chain Reaction (PCR) microsystems for DNA amplification and identification, micromachined Scanning Tunneling Microscopes (STMs), biochips for detection of hazardous chemical and biological agents, and microsystems for high-throughput drug screening and selection.

RF MEMS
High frequency circuits will benefit considerably from the advent of the RF-MEMS technology. Electrical components such as inductors and tunable capacitors can be improved significantly compared to their integrated counterparts if they are made using MEMS and Nanotechnology. With the integration of such components, the performance of communication circuits will improve, while the total circuit area, power consumption and cost will be reduced. In addition, the mechanical switch, as developed by several research groups, is a key component with huge potential in various microwave circuits. The demonstrated samples of mechanical switches have quality factors much higher than anything previously available. Reliability and packaging of RF-MEMS components seem to be the two critical issues that need to be solved before they receive wider acceptance by the market.

Accelerometers
MEMS accelerometers are quickly replacing conventional accelerometers for crash air-bag deployment systems in automobiles. The conventional approach uses several bulky accelerometers made of discrete components mounted in the front of the car with separate electronics near the air-bag; this approach costs over $50 per automobile. MEMS and Nanotechnology has made it possible to integrate the accelerometer and electronics onto a single silicon chip at a cost between $5 to $10. These MEMS accelerometers are much smaller, more functional, lighter, more reliable, and are produced for a fraction of the cost of the conventional macroscale accelerometer elements.

■ Typical of MEMS Applications

   - Inertial measurement devices
   - Microfluidics devices
   - Optical devices
   - Pressure measurement devices
   - RF devices