EE-535 Introduction to MEMS
Prof. Arda Deniz Yalçınkaya
Boğaziçi University
Electrical and Electronics Engineering Dept.
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Background
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Requirements
Basic linear system theory
Basic circuit theory
Basic knowledge about electromechanics
Differential equations
Basic dynamics and mechanics
And basic solid-state physics
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Course Outline
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Syllabus
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MEMS Basics
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Definition: Micro-structures that can move (narrow def.)
Main drivers: Sensing and Actuation
Accelerometers/Gyroscopes
Pressure/Stress sensors
Optical switches/routers
Mechanical resonators
RF passive components
Microfluidics
Optical scanning
Micro & Nano manipulators/grippers
Biosensors
Spectroscopy/Imaging systems
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Feynman's challenge #1
$ 1000 to the first person who builds an operational electric motor which
fits into 1/64 inch-cube.
a)
b)
Richard Feynman viewing the micromotor built by William McLellan (left)
who won the challenge to build the first motor smaller than 1/64th of an
inch.
The motor, 3.81 mm wide, photographed under an optical microscope.
The huge object above it is the head of a pin.
From Physics Web
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Feynman's challenge #2
• $ 1000 for the first person fitting entire Ency. Brittanica on the head
of a pin (60,000 pages)
5.9 μm
Silicon Nitride Membrane
E-Beam Lithography
Pease and Newman, 1985
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Feynman Grand Prize
• Feynman Grand Prize of $250,000
• The Feynman Grand Prize will be awarded to the first team who designs, constructs, and
demonstrates both a functional nano-scale robotic arm and a functional nano-scale
computing device with specified features.
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Motivation and Challenges for MEMS
• MEMS is a “spin-off” from IC technology
• Same motivation as microelectronics:
Inexpensive fabrication in large quantities
• Challenges:
• Expensive fabrication facilities (cleanrooms) (For R&D $ 5-10M, for
volume production fab ~$ 1B)
• Complex nature of the devices (interactions between different domains)
• Prototyping and packaging: long fabrication periods
• Virgin research fields
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Capabilities of MEMS
• Miniaturization (with submicron precision)
• Small size
• Small mass (no gravity effects)
• Small cost
• Low power
• Many functionalities on one-chip
• Movable mechanical structures (sensors and actuators)
• Optical components
• Electronics
• Production
• Wafer scale fabrication (Batch)
• Mass (Volume) production
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Three Main Disciplines
Micro
Optics
Optomechanics
Micro
Mechanics
Integrated
Photonics w.
MEMS
MEMS on
Electronics
OptoElectronics
Micro
Electronics
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Some MEMS Examples
CC-beam resonator
(Nanoresonator)
SOI torsional
resonator
GaAs force sensor
TI-Digital Light
Processor (DLP)
Roukes, 2001.
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MEMS Design and Modeling
Designer
Inputs
System
High-level
simulations
Device
Analytical,
Macro-models Physical
Sim
ula
Numerical, FEA
tio
n
Ver
ific
ati
on
Process
TCAD
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Two-port Approach
Electrical
port
Electrical
port
Electro
Mechanical
System
Electro
Mechanical
System
Mechanical
port
Mechanical
port
Electro
Mechanical
System
Electrical
port
Intrinsic cascading !
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Analogies
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MEMS Fabrication
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Start with a Substrate (wafer)
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Deposit thin films (organic, metal, semiconductor, insulator … )
Create masks (Pattern surface structures)
Remove sacrificial layers (surface micromachining)
Remove parts of the substrate (bulk machining)
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Fabrication Loop
Patterning:
Photoresist
Thin film
Substrate
Deposition:
-Epitaxy
-Oxidation
-Physical Vapor Deposition
-Chemical Vapor Deposition
-Spin-on method
-Sol-gel method
-Bonding
-Optical lithography
-E-beam writing
-Laser direct writing
-AFM lithography
-Self-assembly etc.
Etching:
-Wet
-Dry
Alternatively;
-Isotropic
-Anisotropic
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Actuation-sensing and fabrication
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