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MEMS and NEMS

Raj Nagarajan, Ph.D.

Professor

Electronics and Advanced Technologies

Austin Community College

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Objective

The objective of the module is to introduce micro- and nano -electromechanical systems to two year community college students with special emphasis on the development, processing, applications, and materials that are currently in use to produce MEMS/NEMS.

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Topics

• Introduction• Brief History• Electromechanical Systems• MEMS• Current Applications• NEMS and Nanotechnology• Impact of Miniaturization• Challenges and Possibilities• References

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Introduction

Figure 5.1: Jonathan Swift.

Courtesy Sandia National Laboratories, SUMMiT™ Technologies, www.sandia.gov/mstc.

Figure 5.1: Drive gear chain and linkages, with a grain of pollen (top right) and coagulated red blood cells (lower right, top left) to demonstrate scale.

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Figure 5.2: The Scale of Things.

Introduction, Continued

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• MST - Microsystems Technology (European)

• MEMS - Microelectromechanical Systems (U.S.)

– Manmade devices created using compatible microfabrication techniques that are capable of

• Converting physical stimuli, events and parameters to electrical, mechanical & optical signals

• Performing actuation, sensing and other functions

Introduction, ContinuedDefinition and Terms

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Figure 5.3: Spider mite with legs on a mirror drive assembly.

Introduction, Continued

Image Courtesy of Sandia National Laboratories, SUMMiTTM Technologies, www.mems.sandia.gov

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1962 Silicon Integrated piezo actuators BY O.N. Tufte et al.

1967 Anisotropic deep silicon etching H.A. Waggener

1967 The resonant gate transistor by H. Nathanson, et.al

1972 National Semiconductor - Pressure Sensor

1979 Thermal inkjet technology is invented at HP laboratories

1982 “Silicon as a Mechanical Material” K. Peterson

1982 Liga Process (KFIK, Germany)

1983 “Infinitesimal Machinery” R. Feynman

1983 Silicon Micromechanical devices – J.B.Angel etc.

1983 Integrated Pressure Sensor – Honeywell

1985 Airbag Crash Sensor

1987 Dr. Hornbeck Digital Micromirror Device or DMD (DLP by Texas Instruments)

Later in 1990s micromachining begins leveraging microelectronics industry

1993 Accelerometer integrated with electronics Analog devices

1994 DRIE Etching (Bosch process is patented)

1999 Optical network switch - Lucent

Brief History

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Figure 5.4: Electromechanical Systems functional block diagram.

Electromechanical SystemsFunctional Block Diagram

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• Materials

• Crystallography – Forms of Silicon

– Amorphous

– Polycrystalline

– Crystalline

• “Miller Planes”

Figure 5.5: Miller Indices, Direction Examples

MEMSMicrostructure Fabrication

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• Pattern definition– Photolithography

• Deposition– Oxidation, chemical-vapor deposition,

ion implantation• Removal

– Etching, evaporation

-Structural layer-Sacrificial layer

deposit

pattern

etchFigure 5.6: Microstructure Fabrication

MEMS, ContinuedMicrostructure Fabrication, Continued

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MEMS, Continued

Processing Techniques• Deep Reactive Ion Etching (DRIE)

• Surface Micromachining

• LIGA process – Lithography / Electroplating / Molding

• SUMMIT process

Microstructure Fabrication, Continued

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MEMS Advantages

The advantages of MEMS devices include

• Size

• High sensitivity

• Low noise

• Reduced cost

• Batch Processing

The applications for MEMS are so far reaching that a multi-billion dollar market is forecast. Key industry applications include transportation, telecommunications and healthcare.

MEMS, Continued

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Worldwide MEMS MarketsWorldwide MEMS Markets(in Millions of $)(in Millions of $)

2002 2007

Microfluidics 1401 2241

Optical MEMS 702 1826

RF MEMS 39 249

Other actuators 117 415

Inertial sensors 819 1826

Pressure sensors 546 917

Other sensors 273 830

TotalTotal 39003900 83008300

Figure 5.7: Worldwide MEMS Market (2002 vs. 2007)

MEMS Economy

MEMS, Continued

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• Accelerometers

• Micro Optical Electro Mechanical Systems (MOEMS)

– Digital Mirror Devices (DMD) used in Projection Devices

– Deformable mirrors

– Optical Switches

• Inkjet Print heads (Microfluidics)

• Pressure Sensors

• Gyrometers

• Magnetic RW heads for hard drives

•  Seismic Activities - Thermal transfer

Current Applications

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• Micro-arrayed biosensors

• Virus detection

• DNA Chip PCR (Polymerase Chain Reaction)

• Neuron probes (nerve damage/repair)

• Retina/Cochlear Implants

• Micro Needles

• ChemLab

• Micro Fluidic Pumps

- Insulin Pump (drug delivery)

Biomedical

Current Applications, Continued

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• Hand held detectors – biological & chemical microsensors

– Chem’s Lab on a Chip (security applications)

• Micro and Radio Frequency (RF) Switches

• RFID Technologies

– Modern “bar-coding” system increasingly used on toll roads and materials handling applications

• Data Storage Systems

– IBM Millipede storage system – AFM tip writes data bit by melting a depression into polymer mediaum and reads data by sensing depressions.

Detection systems

Current Applications, Continued

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• Nanotechnology– manipulation of matter at the

nanometer scale.

• Nanomaterials– Started with carbon.– Behavior depends on

morphology.

Figure 5.8: Eight allotropes of carbon:Diamond, graphite, lonsdaleite, C60, C540, C70, amorphous carbon and carbon nanotube

NEMS and Nanotechnology

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• Quantum dots

• Nanowires

• Quantum films

Figure 5.9: Quantum Dots.

NEMS and Nanotechnology, Continued

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• Electrostatic manipulation

• Moving one electron or molecule at a time

• Patterning

• Dip Pen Lithography

• Electron Beam Lithography

• Self assembly

Nano Fabrication

NEMS and Nanotechnology, Continued

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• Cantilever Sensors

• Mass Storage – (IBM) Millipede chip– Nanochip

• Molecular Electronics– Transistors– Memory cells– Nanowires – Nanoswitches

Merging of technologies

NEMS and Nanotechnology, Continued

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Cantilever sensors are essentially MEMS cantilevers with chemical arrays attached. The cantilevers, acting much like tuning forks, have a natural frequency of vibration which changes as more mass is attached (nano function). The change in frequency is sensed by the MEMS device indicating a measurable presence in the system of particular reacting compound.

Selective chemical layer

Reacting compound

cantilever

Figure 5.10: Cantilever sensor

Merging of technologies

NEMS and Nanotechnology, Continued

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• Potential Positive Impacts– Reduction of disease.– Job opportunities in new fields.– Low-cost energy.– Cost reductions with improved efficiencies.– Improved product and building materials.– Transportation improvements

• Potential Negative Impacts– Material toxicity– Non-biodegradable materials.– Unanticipated consequences.– Job losses due to increased manufacturing efficiencies.

Impact of Miniaturization

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• Fundamental and applied research

• Engineering and technological developments

• High Fidelity Modeling

• High Yield / Low Cost Fabrication

• “Molecular manufacturing”

Challenges and Possibilities

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References

• Gad-el-Hak, M. MEMS, Design and Fabrication, Second Edition. (2005)

• Lyshevski, S., MEMS and NEMS, CRC Press LLC. (2002) • Maluf, N. and Williams, K., An Introduction to Micromechanical

Systems Engineering, Second Edition, Artechouse, Inc. (2004)• Microsytems, Same-Tec 2005 Preconference Workshop, July 25

&26, 2005.• Taylor and Francis, MEMS Introductory Course, Sandia National

Laboratories, June 13-15, 2006.• What is MEMS technology? MEMS and Nanotechnology

Clearinghouse. http://www.memsnet.org/mems/what-is.html.