Microsystems: The Power of SMALL

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Microsystems The Power of SMALL

• Rosemary L. Smith
• MicroInstruments Systems Laboratory (MISL)
• Dept. Electrical Computer Engineering
• UCDavis

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Microsystems

• What are they?
• Microfabricated Systems
• the integration of microfabricated sensors,
  actuators, and electronics on a common substrate
  or in a single package.
• a.k.a. MicroElectroMechanical Systems (MEMS)
• Optical MEMS
• RF MEMS
• BioMEMS

Biological System Microsystem brain microprocess
or eyes, ears, nose microsensors arms, legs,
fingers microactuators heart
circulation microfluidics lungs digestive
track power source vocal cords display
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Why Microsystems?
Mechanical, optical, magnetic, chemical, and
electronic devices are manufactured using silicon
integrated circuit fabrication technology

• Paradigm shift new way of thinking!
• Batch Fabrication
• low-cost, small size, sophisticated electronics
  vacuum tubes to Pentium !
• Photolithographic patterning
• dimensional precision, reproducibile
• Millions of components High functionality.

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IC Manufacturing Process
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Photopatterning
photoresist spun on wafer
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• Fabrication is independent of the complexity of
  the pattern.
• Mass production
• many chips per wafer
• many wafers per batch
• many batches per day

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Microfabrication

• The Promise
• Improved manufacturing
• Batch fabrication
• Precise dimensional control
• Well established IC technology
• New types of sensors and structures
• New materials
• New structures, by micromachining
• New Sytems capabilities
• Integration
• Auto-reconfiguring
• Swarms
• Lower Cost
• Better Performance
• More Function per unit volume

Invest NOW !
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Microelectronic Devices as Sensors
Resistors .Strain Capacitors
Displacement Diodes Optical Transistors
pH Circuits Temperature

• Proportional To Absolute Temperature (PTAT)
  circuit AD590
• R 1 µA/K , - 55 C ltTlt 150 C

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Ion Selective Field Effect Transistor
MOSFET
Ion Selective Membrane
S. D. Collins, UCDavis
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Micromachining

• Collection of technologies that create 3D
  microstructures on or within a substrate.
• Surface Micromachining
• Bulk Micromachining
• wet chemical etching
• dry plasma etching Reactive Ion Etching
• LIGA electroforming
• MicroMolding
• SU-8 Photocured epoxy

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Surface Micromachining
Structural Layers Sacrificial Layers Etchant Polys
ilicon (Silicon) Silicon Dioxide HF Polymers Metal
s Metal Etches Metals Organics Solvents
Cantilever
Bridge
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Multiple Levels gt Complex Structures
Multiple Structural Layers
Multiple Sacrificial Layers
Etch Sacrificial Layers
Anchored Joints
Substrate
Free Standing Joints
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Surface Micromachines
http//mems.sandia.gov/scripts/images.asp
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Bulk Micromachining

• Anisotropic Etching
• (Silicon in KOH)
• All crystal planes etch much faster than 111

(100)/(111) plane intersection 54.7o
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Micromachined Sensors

• Pressure Sensor
• Thin Silicon Membrane deforms with pressure
• Piezoresistors change with strain induced by
  bending membrane
• Packaging requires sealing to maintain pressure
  differential

Photo of a packaged pressure sensor Motorola, Inc.
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Accelerometer

• Accelerometer for automobile air bag
• Surface micromachined, capacitive sensor
• Sensor Electronics on same substrate smart

Analog Devices ADXL-50
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Actuators
C. Keller MEMS Precision Instruments http//www.me
mspi.com
Micro light-bulb
Micro Switch
UCDavis
K. Petersen, IBM
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Pump Flow Sensor

• Flow
• differential pressure across an integrated
  channel.
• Pump
• piezo-electric disk sitting on top of a thin,
  silicon membrane.
• Combined assembly
• measures 6.0x2.5x9 cm.

Flow Sensor
Piezo-electric Pump
B. Van der Schoot and M. Boillat University of
Neuchatel, Switzerland
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Microthruster
UCDavis
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Micromotors
MCNC Electrostatic Micromotor

• Motors, engines and turbines all have been made
  in and on silicon.

UCDavis
Nickel LIGA gear Sandia National Labs
Si Bulk micromachined Linear Synchronous Motor
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Microfluidics

• Micro droplet manipulated by electrowetting of
  electrodes
• C. J. Kim, UCLA
• http//cjmems.seas.ucla.edu

• Fluid transport from needles to microchannel by
  capillary force
• E. Mukerjee, UCDavis

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Micro Power Sources

• Micro Fuel Cell
• J. Morse, LLNL

Lawrence Livermore National Laboratories
http//www-eng.llnl.gov/explo_resear/mems_pg2.html
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Surface Plasmon Resonance Microsystem
MicroInstruments Systems Laboratory, MISL
UCDavis
UCDavis

• A multi- layer, assembly of microfabricated
  components
• Mechanical Torsional Micromirror
• Optical GRIN Lens Optical Fiber
• Position Sensitive PhotoDiode
• Alumina Hybrid Electronic Substrate

Operation Polarized optical beam reflects off a
thin metal film. At the resonance angle, the
optical energy is completely converted into a
surface plasmon (zero reflection). The SPR angle
is a strong function of the surface dielectric.
http//www.ece.ucdavis.edu/misl/Homepage.htm
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SPR Response
MicroInstruments Systems Laboratory, MISL
UCDavis
Response of SPR to avidin adsorption on a
biotynilated gold surface
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Micro-ALPS?

• Number of sensors
• information
• Functions
• capability
• Lifetime
• Reduction in power
• redundancy

If MEMS can fly, then why shouldnt they swim?

• K. Pister, BSAC

http//robotics.eecs.berkeley.edu/pister/smartdus
t