Transcript Notes

Introduction to MEMS;
energy domains; mechanical and
fluidic devices
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MEMS (Microelectromechanical systems)
(Other commonly used terms: Microsystems (Europe); Microfluidics;
Mechatronics (Japan) )
All these terms refer to "systems" incorporating electrical elements
and elements from other domains into a "chip" or "integrated circuit".
Both miniaturization and integration are usually implied.
Another term commonly used is "SOC", which stands for "system on
a chip".
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Motivations for MEMS:
-----space (area) savings
-----power reduction (can we use batteries?)
-----portability (reduced weight / power)
-----reliability--because of integration
-----economic savings--"mass produce" elements as VLSI chips are
currently produced
-----application of well-understood VLSI processing techniques to
other domains
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Application areas (a sampling)------automotive systems
-----environmental control / monitoring
-----health care
-----defense systems
----- automated manufacturing
Example applications (see, e.g., Analog Devices website,
www.analog.com)::
--airbags: change in acceleration (force) is translated into signal to
deploy airbag
--navigation and stabilization: micro gyroscopes provide a frame of
reference in navigation and stabilization systems in cars, planes, etc.
--”lab on a chip”: biological / chemical procedures can be carried
out on one integrated chip (Lab on a Chip journal:
http://www.rsc.org/is/journals/current/loc/locpub.htm)
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Area is INHERENTLY MULTIDISCIPLINARY (based on
today's "disciplines")
How old is this area? (~ 30 years)
basic reference:
K. Petersen, Silicon as a mechanical material, IEEE Proceedings
70 (5), May 1982, 420-457.
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Basic idea: IC's perform (electronic) calculations extremely well;
I/O is NOT generally in the electrical domain--how can I/O
elements (“sensors” and “actuators”, or "transducers")be
integrated?
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Energy Domains:
1. thermal--temperature, heat, heat flow, etc.
2. mechanical--force, pressure, ve;ocity, acceleration, position, etc.
3. chemical--concentration, material composition, reaction rate, etc.
4. magnetic--magnetic field intensity, flux density, magnetization,
etc.
5. radiant--intensity, wavelength, polarizaion, phase, etc.
6. electrical--voltage, current, charge, etc.
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Relation to IC's:
Typical IC is built up of "layers" of material. These layers can be
used to make other devices, e.g., cantilever beams for sensing and
actuating
Techniques for "machining" are those used in IC fabrication--how
can they be used / modified to make devices usable in other
domains?
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Devices are generally divided into two classes according to
processing required:
a. "surface micromachining" (2.5D devices)
uses “layers”
b. "bulk micromachining"
(true 3D devices)
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examples:
beams
cantilever beams
membranes
ducts
motors, movable parts
http://www.sfu.ca/immr/projects/ensc494-01/acoppin/designs.html
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How can MEMS development make use of well-understood IC
CAD capabilities?
What extensions are needed for CAD for MEMS?
Recall:
1. Predicting IC performance requires input from fabrication,
design, and environment.
2. Tools for incorporating information from each of these domains
are necessary for "rapid prototyping" which make many
IC designs economically feasible.
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Comparisons of Mechanical Properties (Petersen)
Property
Si
SiO2
Steel
Al
Yield
(1010 dyne/cm2)
7.0
8.4
4.2
0.17
Hardness
(kg/mm2)
850
820
1500
130
Young's mod
(1012dyne/cm2)
1.9
0.73
4.9
0.7
Density
(gr/cm3)
2.3
2.5
7.9
2.7
Therm. cond
(W/cmoC)
1.57
.014
0.97
2.36
Thermal exp
(10-6/oC)
2.33
0.55
12
25
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Tasks: Specify-Design-Simulate-Fab-Test-Maintain
=====================================================================================
LEVELS||
VIEWS
|| Behavioral
Structural
Physical
=====================================================================================
4
|| Specifications,
CPUs,Memory,
Partitions
|| Systems
Switches, Complex
||
MEMS
-----------------------------------------------------------------------------------------------------------------------------------------------3
|| Algorithms
Data Structures
Clusters
-----------------------------------------------------------------------------------------------------------------------------------------------2
|| Register Transfers
ALUs, Registers,
Floorplans
||
Electromechanical
||
Components
----------------------------------------------------------------------------------------------------------------------------------------------1
|| Boolean Equations,
Gates, Flip-flops,
Cells,
|| FSMs, Mechanical
Sensors, Actuators
Modules
|| Behavior
----------------------------------------------------------------------------------------------------------------------------------------------0
|| Transfer Functions
Transistors, Wires,
Layout
||
Contacts, Vias,
Geometry
||
Beams, Membranes,
||
Holes, Grooves,
||
Joints
====================================================================================
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MEMS