Microelectromechanical Systems
(MEMS) based advanced high
performance Radio Frequency (RF)
systems
Outline
••
••
Introduction
Introduction
What
What are
are MEMS
MEMS
–– Why
Why use
use MEMS
MEMS –– advantages
advantages
–– How
How are MEMS
MEMS fabricated
fabricated
–– MEMS
MEMS actuation
actuation techniques
techniques
•• RF
RF MEMS
MEMS
–– Fabrication
Fabrication
–– Applications
Applications
–– Advantages
Advantages
–– MEMS
MEMS switch
switch library
library
–– Design
Design and
and analysis
analysis
–– Failure
Failure mechanisms
mechanisms
–– Challenges
Challenges
–– Conclusions
Conclusions
What are MEMS?
••
MEMS
MEMS are
are Micro
Micro Electro-Mechanical
Electro-Mechanical Systems
Systems
••
MEMS
MEMS typically
typically have
have both
both electrical
electrical and
and mechanical
mechanical
components
components
••
As
As microelectronics
microelectronics has
has shown,
shown, size
size doesn’t
doesn’t necessarily
necessarily
matter
matter
••
Envisioned
Envisioned by
by Sci-Fi
Sci-Fi authors
authors
••
R.P.
R.P. Feynman
Feynman –– “There’s
“There’s lots
lots of
of room
room at
at the
the bottom”
bottom”
••
First
First MEMS
MEMS Publication
Publication ::
–– H.C.
H.C. Nathanson,
Nathanson, et
et al.,
al., The
The Resonant
Resonant Gate
Gate Transistor,
Transistor,
IEEE
IEEE Trans.
Trans. Electron
Electron Devices,
Devices, March
March 1967,
1967, vol.
vol. 14,
14, no.
no.
3,
3, pp
pp 117-133
117-133
••
Pressure
Pressure sensors
sensors were
were the
the first
first MEMS
MEMS products
products
–– Si
Si diaphragms
diaphragms and
and diffused
diffused piezo-resistors
piezo-resistors
••
Surface
Surface m-machined
m-machined accelerometers
accelerometers and
and flow
flow sensors
sensors
Why MEMS?
•
•
•
•
•
•
•
•
Miniaturization with no loss of functionality
Integration to form a monolithic system
Improved reproducibility, reliability and accuracy
Exploitation of new physics domains
Low power
Fast actuation techniques
Improved selectivity and sensitivity
MEMS may be the ONLY solution
MEMS enables advances in many business
areas…
Optics
• Micromirrors
• Silicon
Benches
• Waveguided
structures
• Integrated
subsystems
• Optical
transparency
• Ease of
manufacture
• High precision
• High reliability
• Integration of
multiple
subsystems
Life Sciences &
Laboratory
Equipment
• Micronozzles
• Micropumps
• Membranes
• Microfluidic
channels
• Wells &
reservoirs
• Waveguides
• Lab-on-a-chip
• Economical use
of samples
• Low cost assays
• Quick turnaround
on sample
analysis
• Reduction in
equipment
footprint
RF
• Capacitors
• High-Q
inductors
• Resonators
• Relays and
Switches
• Integrated
subsystems
• Low weight
• Low insertion
loss
• High off-state
isolation
• High precision
• Low power
consumption
• High reliability
Some MEMS Applications
Ultrasound Transducer
Gyroscope
Optical Scanner
Microphone
Accelerometer
2-Axis Micromirror
Overall, the market is poised for breakaway
growth
$30
$20
$10
$ US Billions
Growth of International MEMS Market
2008
2005
2002
1999
1996
1993
1990
$0
Year
Source: Aggregate of data presented in MST News 5/01, including data from SPC, SRI,
NEXUS, Batelle, VDC, and other research organizations
New applications for MEMS emerge and grow
quickly
2001
Industrial
25%
Consumer
1%
Medical
16%
Automotive
31%
2006
Comm.
1%
Computer
26%
Medical
11%
Industrial
22%
Consumer
3%
Comm.
21%
Source: In-stat 2002
Automotive
17%
Computer
26%
Fabrication of MEMS
•• Typically
Typically the
the fabrication
fabrication of
of MEMS
MEMS uses
uses tools
tools from
from the
the semiconductor
semiconductor
industry,
industry, plus
plus many
many other
other tools:
tools:
–– Photolithography
Photolithography
–– Diffusion
Diffusion
–– Oxidation
Oxidation
–– Etching
Etching (isotropic
(isotropic and
and anisotropic,
anisotropic, wet
wet and
and plasma)
plasma)
–– Chemical
Chemical Vapor
Vapor Deposition
Deposition (Si3N4,
(Si3N4, SiO2,
SiO2, Polysilicon,
Polysilicon, etc.)
etc.)
–– Vacuum
Vacuum Metal
Metal Deposition
Deposition (sputtering,
(sputtering, evaporation)
evaporation)
–– Electroplating
Electroplating (LIGA, Ni, Au, Cu microstructures)
–– Chemical
Chemical Mechanical
Mechanical Polishing
Polishing to
to produce
produce flat
flat surfaces
surfaces
–– Wafer
Wafer Bonding,
Bonding, SOI
SOI wafers
wafers
–– Deep
Deep Plasma
Plasma Etching
Etching (Inductively
(Inductively Coupled
Coupled Plasma)
Plasma)
–– Sol-Gel
Sol-Gel deposition
deposition (PZT)
(PZT)
Bulk Micromachining
••
••
••
Single
Single Crystalline
Crystalline Silicon
Silicon
Isotropic
Isotropic Etching
Etching (HNA etc.)
Anisotropic
Anisotropic Etching (KOH, TMAH,
EDP
EDP etc.)
etc.)
•• Reactive
Reactive Ion
Ion Etching
Etching (RIE
(RIE &
& DRIE)
DRIE)
•• Accommodates
Accommodates sharp
sharp corners,
corners, small
small
features
features and
and very
very smooth
smooth surfaces
surfaces
LIGA Process
••
••
••
••
••
Electroplated
Electroplated microstructures
microstructures
X-ray
X-ray Photolithography
Photolithography in
in PMMA
PMMA polymer
polymer resist
resist
Very
Very high
high aspect
aspect ratio
ratio microstructures
microstructures with
with smooth
smooth surfaces
surfaces
Used
Used to
to create
create molds
molds for
for low
low cost
cost replication
replication of
of precision
precision shapes
shapes
Molded
Molded diffraction
diffraction grating
grating for
for match-box
match-box spectrometer
spectrometer
Surface Micromachining
••
••
••
••
Primarily
Primarily Poly-Si
Poly-Si thin-film
thin-film structures
structures
Make
Make structures
structures horizontally
horizontally and
and erect
erect them
them
on
on aa hinge
hinge
MUMPS,
MUMPS, SUMMIT,
SUMMIT, HEXSIL
HEXSIL etc.
etc.
Applications
Applications
–– Pop-up
Pop-up micro-mirrors
micro-mirrors
–– Pressure
Pressure sensors
sensors
–– RF
RF switches
switches
A
B
C
D
E
Si
Phosphosilicate glass
Polysilicon
Capacitive MEMS RF Switch Fabrication
•• Surface
Surface micromachining based
fabrication
fabrication process
process
–– oxide
oxide deposition,
deposition, electrode,
electrode,
dielectric
dielectric deposition
deposition and
and
patterning
patterning
–– metal
metal posts
posts deposition
deposition and
and
patterning
patterning
–– spacer
spacer coating
coating and
and patterning
patterning
–– membrane
membrane deposition
deposition and
and
patterning
patterning
–– removal
removal of
of spacer
spacer layer
layer by
by
dry
dry or
or wet
wet etching*
etching*
*Yao, Z., Chen, S., Eshelman, S., Goldsmith, C., “Micromachined low-loss microwave switches”,
IEEE, J. MEMS, Vol 8, pp 129–34, 1999
MEMS Actuation Techniques
Mechanism
Advantage
Disadvantage
Rockwell
Electrostatic
Fast
High voltage
Cronos
Georgia Tech
Thermal
Magnetostatic
High force,
Fast,
bi-directional
high force,
Quiescent
bi-directional
power,
Quiescent
slow
power
Marconi
Piezoelectric
Fast
Small throw
Microlab
Latching
Magnetic
Fast,
high force,
bi-directional
Construction
Series Switches
Rebeiz/Muldavin/Rizk
Shunt Capacitive Switches
Rs1
G
Rs1
Zo, a, bl
L
W
C
Zo, a, bl
L
CPW
Rs
L
MEMS bridge
g
w
Rs1
w
G
Microstrip
Rs1
Zo, a, bl
L
W
C
L
Rs
via
Rebeiz/Muldavin/Rizk
Lvia
Rvia
Zo, a, bl
G
Circuit metal
W
Thin dielectric
layer
MEMS Ohmic Switch Technology
HRL Laboratories
Rockwell
Analog Devices
Motorola
Chronos
Microlab
Ohmic Contact Switch
Companies
Rockwell Scientific
HRL Laboratories
Analog Devices
Motorola
Chronos
Omron
Microlab
Several standard MEMS fabs
Switch Construction
Metallizations
Gold, aluminum, nickel
Substrates
Silicon, gallium arsenide
Actuation Mechanisms
Electrostatic, thermal,
magnetic
CoCo-integration
microwave electronics
MEMS Capacitive Switch Technology
Raytheon
MIT Lincoln Labs
Bosch
Capacitive Contact Switch
Companies
Raytheon
NorthropNorthrop-Grumman
Samsung
LG Electronics
MIT Lincoln Labs
DaimlerDaimler-Chrysler
Bosch
Samsung
LG Electronics
DaimlerDaimler-Chrysler
Switch Construction
Metallizations
Gold, aluminum, copper
Substrates
Silicon, quartz,
gallium arsenide
CoCo-integration
CMOS
Radio Frequency Applications
Technology
Bulk Micromachining
Surface Micromachining
Micromachining - fab of
3D structures on an IC
MEMS - movable
structure micromachined
into an IC
Cornell
Rockwell
DaimlerDaimler-Chrysler
U Michigan
Transmission Lines
Variable Capacitor
Switch
Filter
Devices
These devices are the “transistor” of a new generation of mechanical IC devices!
Rockwell
Raytheon
Circuits
5-Pole Bandpass Filter
Electronic Phase Shifter
MEMS are creating a revolutionary impact on RF technology!
Opportunity for Applications of RF MEMS
Application Areas for MEMS RF
Comparison: MEMS versus Solid-state switches
Advantages of RF MEMS
Performance
Performance
Ultra-low
Ultra-low RF
RF loss
loss –– Beats
Beats any
any available
available electronics
electronics technology
technology for
for
switching
switching or
or tuning
tuning of
of RF
RF signals
signals
Essentially
Essentially no
no DC
DC power
power consumption
consumption –– Perfect
Perfect for
for battery
battery and
and low
low powerpowerconsumption
consumption applications
applications
Extremely
Extremely high
high linearity
linearity –– Creates
Creates no
no harmonics
harmonics or
or distortion,
distortion, excellent
excellent for
for
broadband
broadband communications
communications
Size
Size
Microminiature
Microminiature size
size –– Reduced
Reduced size
size with
with unmatched
unmatched performance,
performance, able
able to
to
work
work at
at very
very high
high frequencies
frequencies (>
(> 50
50 GHz)
GHz)
Tunability
Tunability –– Supports
Supports reduction
reduction in
in number
number of
of passive
passive components,
components,
combines
combines numerous
numerous switched
switched parts
parts into
into one
one tunable
tunable chip
chip
Cost
Cost
Reduced
Reduced IC
IC costs
costs –– Low
Low cost,
cost, batch
batch fabrication.
fabrication. Much
Much less
less expensive
expensive than
than
competing
competing exotic
exotic semiconductor
semiconductor technologies.
technologies.
Significant
Significant system
system cost
cost impact
impact -- Able
Able to
to be
be combined
combined with
with other
other electronics
electronics
for
for “system-on-a-chip.”
“system-on-a-chip.” Improved
Improved functionality
functionality can
can greatly
greatly reduce
reduce cost.
cost.
RF MEMS Switches Are
Much Simpler than PIN Diode Switches
PIN Diode Switch Circuit
RF MEMS Switch Circuit
+Vcontrol
DC Control Voltage
–Vcontrol
C
In
Out
L
In
C
L
C
C
R
0.0025 sq inch
One
< 1 nanowatt
Area
DC Control Voltages
DC Control Power
0.25 sq inch
Two: + and –
~300 milliwatts
Out
Companies/ Univ./Labs Developing MEMS
switches
••
••
••
••
••
••
••
••
••
••
••
••
••
Raytheon
Raytheon // (Texas
(Texas Instruments)
Instruments)
Raytheon
Raytheon // (HRL)
(HRL)
Rockwell
Rockwell Science
Science Center
Center
Northrop
Northrop Grumman
Grumman
Motorola
Motorola
Analog
Analog Devices
Devices
Lincoln
Lincoln Labs
Labs
Dow-Key
Dow-Key Microwave
Microwave (with
(with HRL)
HRL)
Sarnoff
Sarnoff Labs
Labs
Sandia
Sandia Labs
Labs
Bosch,
Bosch, Germany
Germany
DaimlerChrysler,
DaimlerChrysler, Germany
Germany
Thompson-CSF,
Thompson-CSF, France
France
••
••
••
••
••
••
••
••
••
••
••
University
University of
of Michigan
Michigan
Univ.
Univ. of
of Illinois,
Illinois, Urbana
Urbana
Univ.
Univ. of
of California,
California, Berkeley
Berkeley
Northeastern
Northeastern University
University
And
And other
other small
small efforts
efforts at
at many
many
European
European and
and Japanese
Japanese Univ.
Univ.
Samsung,
Samsung, Korea
Korea
Sony,
Sony, Japan
Japan
MEMSCAP,
MEMSCAP, France
France
Corning
Corning IntelliSense
IntelliSense
LG-Corporate
LG-Corporate Research,
Research, Korea
Korea
NEC,
NEC, Japan
Japan
Raytheon
0
0
-5
-1
-10
-1.5
-15
-2
-20
-2.5
-25
-3
Return Loss (dB)
Insertion Loss (dB)
-0.5
-30
Capacitor Up
-3.5
-35
-4
-40
0
5
10
15
20
25
30
35
40
Frequency (GHz)
0
0
-5
Capacitor Down
-10
-10
-15
-15
-20
-20
-25
-25
-30
-30
-35
-35
-40
-40
-45
-45
-50
-50
0
5
10
15
20
25
Frequency (GHz)
30
35
40
Return Loss (dB)
Isolation (dB)
-5
Insertion Loss @ 40 GHz
Isolation @ 40 GHz
<0.07
>35
Model Values
Rs
0.11
0.2
Rsh
CON/OFF
0.03-0.045
Coff
3.4
Con RSH
RSH
0.25
Ron
Capacitance Ratio
70-110
Cutoff Frequency
18,000
Switching Speed
< 10
Intercept Point
> +66
Switching Voltage
30-50
Size
280 × 170
RSE
RSE
dB
dB
Ohms
Ohms
pF
pF
Ohms
GHz
µs
dBm
volts
µm
HRL
Top View
Side View
RF Out
Switch Open (Signal Isolation)
h
Anchor
Bias
Electrode
RF
Contact
h = 2 µm (0.08 mil)
500 µm
(20 mil)
Switch Closed (Signal Transmission)
Gold
700 µm
(28 mil)
• Metal-Metal contact series switch
• Electrostatic actuation: 20–40 V
• Switching time: 20–40 µsec
– Depends on gap and voltage
RF In
Silicon
Nitride
GaAs
Substrate
• Nitride/gold/nitride tri-layer prevents
creep
• Fabrication process is compatible with
other substrate materials like high
resistivity silicon
0
-15
-0.2
-20
insertion loss (dB)
-25
-0.4
ON
return loss (dB)
-0.6
-35
-0.8
-40
-1
0
10
20
30
40
freq (GHz)
-10
-20
isolation (dB)
-30
-30
isolation (dB)
-40
-50
OFF
-60
-70
0
10
20
freq (GHz)
30
40
return loss (dB)
insertion loss (dB)
Rockwell Science Center
•
•
•
•
•
•
Low insertion loss: 0.1 dB @ 2GHz
Excellent Isolation: -56dB @2 GHz
Turn-on time <10ms
+28dBm power handling capability
Third order intercept 80dBm
Implementation on Si, GaAs, Quartz
Analog Devices
••
••
••
••
••
••
••
DC
DC Contact
Contact Series
Series switch
switch
Vp
Vp = 50-60
50-60 V
V
Isolation:
Isolation: -40
-40 dB
dB (4
(4 GHz)
GHz)
tt == 0.5-3
0.5-3 ms
ms
Isolation:
Isolation: -27
-27 dB
dB (20
(20 GHz)
GHz)
Cu
Cu == 44 fF
fF
Loss
Loss :: -0.1
-0.1 to
to –0.2
–0.2 dB
dB (DC-20
(DC-20
GHz)
GHz)
•• Rs
Rs == 1-2
1-2 W
W
•• (Electrode
(Electrode does
does not
not touch
touch
cantilever)
cantilever)
Muldavin/Rebeiz
MIT Lincoln Lab
0
-0.1
2 thru lines
-0.2
S21 (dB)
-0.3
-0.4
-0.5
-0.6
-0.7
-0.8
9 switches
Vact = 80 V
-0.9
-1
0
5
10
15
20
25
30
35
Frequency (GHz)
RF Measurement (9 Switches)
Contact Resistance:
DC Contact single switch
in CPW configuration
Switch Speed:
95% yield < 2 W
60% yield < 1 W
Closing time: < 1 ms
Opening time: < 1 ms
40
University of Michigan
••
••
••
••
••
••
All
All metal series
series switch
switch
Vp=20-25
Vp=20-25 V
Switching
Switching speed
speed == 10
10 us
us
Cu=4-8
Cu=4-8 fF,
fF, Ron=0.5-2
Ron=0.5-2 Ohms
Ohms
Isolation:
Isolation: -36
-36 to
to –40
–40 dB
dB (4
(4 GHz)
GHz)
Compact
Compact Geometry
Geometry
–– 300
300 um
um by
by 100
100 um
um
•• CPW
CPW or
or Micro-strip
Micro-strip
•• High
High Impedance
Impedance Bias
Bias Line
Line
–– 11 kOhm
kOhm // square
square SiCr
SiCr
Muldavin/Rebeiz
LG Korea
••
••
••
••
••
••
••
••
••
••
High
High Capacitance
Capacitance shunt
shunt
Isolation:
Isolation: -40 dB (3-5 GHz)
Isolation:
Isolation: -30
-30 dB
dB (10
(10 GHz)
GHz)
Isolation:
Isolation: -20
-20 dB
dB (20
(20 GHz)
GHz)
Loss
Loss :: -0.1
-0.1 dB
dB (10
(10 GHz)
GHz)
(LCd
(LCd Resonance
Resonance effect at
at 3-5
3-5
GHz)
GHz)
Vp
Vp = 8-20
8-20 V
V
tt == N/A
N/A
Dielectric:
Dielectric: SrTiO3
SrTiO3
Cd
Cd == 50
50 pF
pF
Movable
Plate
RF input
Hinge
Ground
RF output
Dielectric
Metal
Post
MEMS Physics is Multi-Disciplinary: Mechanics,
Electrostatics, Fluidics, Ionics etc.
†
C-C Beam
Center Cap Top

 Stress in CC Beam
‚ Charge injection into insulator or
contact erosion
ƒ Charge migration over surface
„ Formation of induced channel on
semiconductors
Distributed Mass and Spring
† Large Surface Tension formation
forces
‚
+ + + + + ® ...
2m
200m
†
Cap Base
ƒ „
Design and Analysis of MEMS RF Switches
• Electrostatic domain
– to solve for electrostatic pressure due to parallel surfaces.
• Mechanical domain
– to solve for mechanical deformation, contact, stresses, heat
generation etc.
• Fluidic domain
– to solve for squeeze film dampening effect when the bridge
moves.
• Electromagnetic domain
– to solve for S, Y, Z parameters in order to obtain insertion loss,
isolation and current distribution.
Electromechanical Analysis
Capacitance versus voltage
Deflection versus voltage
1.4000
Deflection ( m)
0
2
4
6
8
10
12
14
16
18
20
- 0.5
-1
- 1.5
-2
22 24
26 28
30
Capacitance (pf)
0
1.2000
1.0000
0.8000
0.6000
0.4000
0.2000
0.0000
- 2.5
0
Voltage (V)
2
4
6
8
10
12 14
16 18 20 22 24 26 28 30
Voltage (V)
Electromagnetic Analysis
0
0
DB(|S[2,1]|)
Measured
-5
-10
-0.1
DB(|S[2,1]|)
Theoretical
-15
-20
-0.2
-0.3
-25
-30
-0.4
-35
DB(|S[2,1]|)
Theoretical
-0.5
-40
-45
-0.6
-50
DB(|S[2,1]|)
Measurement (On)
-0.7
-55
-60
-0.8
2
6
10
14
18
22
26
Frequency (GHz)
30
34
38 40
2
6
10
14
18
22
26
Frequency (GHz)
30
34
Electromagnetic (RF) analysis showing S parameters and
current distribution for a capacitive switch in OFF (left)
and ON (right) positions
38 40
Failure Mechanisms in MEMS Devices
Class I
No Moving parts
Class II
Moving Parts, No Rubbing or
Impacting Surfaces
Class III
Moving Parts,
Impacting Surfaces
Class IV
Moving Parts, Impacting
and Rubbing Surfaces
Applications
Accelerometers
Pressure Sensors
Ink Jet Print Heads
Strain Gauge
Integrated Circuits
Particle Contamination
Shock Induced Stiction
Gyros
Comb Drives
Resonators
Filters
TI DMD
Relays
Valves
Pumps
RF Switches
Optical Switches
Shutters
Scanners
Failure Mechanisms
Particle Contamination
Shock Induced Stiction
Mechanical Fatigue
Particle Contamination
Shock Induced Stiction
Stiction
Mechanical Fatigue
Impact Damage
Particle Contamination
Shock Induced Stiction
Stiction
Mechanical Fatigue
Friction
Wear
Challenges
•
•
•
•
Lifetime and reliability
Packaging
Cost
Speed
Switch Lifetimes: Capacitive Switches
••
••
Stiction
Stiction
–– Metal-to-dielectric
Metal-to-dielectric stiction
stiction
–– Large
Large contact
contact area
area resulting
resulting in
in
stiction
stiction due
due to
to dielectric
dielectric charging
charging
–– Water
Water particle
particle (water
(water is
is aa polar
polar
molecule)
molecule)
–– Organic
Organic materials
materials on
on the
the metalmetaldielectric
dielectric interface
interface
Possible
Possible solutions
solutions
–– Package
Package device
device in
in Nitrogen
Nitrogen
atmosphere
atmosphere (makes
(makes itit very
very
expensive)
expensive)
–– Better
Better design
design and
and dielectrics
dielectrics by
by
reducing
reducing actuation
actuation voltage
voltage
–– Use
Use bipolar
bipolar voltage
voltage so
so as
as not
not to
to
charge
charge the
the dielectric
dielectric (cost
(cost may
may
be
be high
high preventing
preventing use
use in
in
various
various portable
portable applications)
applications)
Packaging Considerations in MEMS Circuits
••
••
••
••
••
Wafer
Wafer level
level packaging
packaging will
will result
result in
in
lowest
lowest cost
cost for
for MEMS
MEMS switches.
switches.
Packaging
Packaging gas
gas has
has large
large effect
effect on
on
reliability.
reliability.
Hermetic
Hermetic sealing
sealing is
is essential
essential since
since
MEMS
MEMS switches
switches are
are sensitive
sensitive to
to
humidity.
humidity.
For
For high
high performance,
performance, low
low
quantities,
quantities, packaging
packaging can
can be
be done
done
using
using standard
standard techniques.
techniques.
The
The highest
highest cost
cost will
will be
be the
the package
package
in
in single
single MEMS
MEMS switches.
switches. This
This is
is not
not
the
the case
case in
in phase
phase shifters
shifters or
or filters,
filters,
or
or high
high isolation
isolation switch
switch networks.
networks.
Conclusions
•• Virtually
Virtually every
every MEMS
MEMS switch
switch configuration
configuration is
is available
available today.
today. The
The main
main
question
question now
now is
is reliability
reliability and
and packaging.
packaging.
11 mechanically.
•• Reliability
electrically, and
and 10
1011
mechanically.
Reliability is
is currently
currently in
in the
the 10
1088 electrically,
•• Failure
Failure mechanisms
mechanisms are:
are:
–– Resistive
Resistive failure
failure in
in DC-contact
DC-contact switches
switches (metallurgy,
(metallurgy, contact
contact forces)
forces)
–– Stiction
Stiction due to humidity and/or charging of the dielectric (capacitive
switches)
switches)
–– Stiction
Stiction due to metal-to-metal contacts (contact physics)
–– Microwelding
Microwelding due
due to
to large
large currents
currents
•• To
To combat
combat failures,
failures, industry
industry is
is doing
doing the
the following:
following:
–– Packaging
Packaging in inert
inert atmosphere
atmosphere such
such as
as Nitrogen
Nitrogen and/or
and/or hermetic
hermetic
sealing
sealing
–– Large
Large voltage
voltage and
and large
large spring
spring constant
constant structures
structures
–– Development
Development of
of better
better metal
metal contacts
contacts
–– Designs
Designs with
with no
no contact
contact between
between the
the pull-down
pull-down electrode and the
bottom
bottom metal
metal (not
(not applicable
applicable for
for current
current capacitive
capacitive switches)
switches)
Conclusions
•• Today,
Today, most
most MEMS
MEMS switches
switches are
are being
being developed
developed for
for phase
phase shifters
shifters and
and
defense
defense applications.
applications.
•• Tomorrow,
Tomorrow, which
which is
is today,
today, most
most MEMS
MEMS switches will be developed for
wireless
wireless applications
applications and
and low-power
low-power applications:
applications:
–– Single-Pole
Single-Pole Multiple-Throw
Multiple-Throw Switches
Switches
–– Switched
Switched Filter Banks for portable and basestations (receive)
–– Switched
Switched Attenuators for High Dynamic Range Receivers and
Instrumentation
Instrumentation
–– Switch
Switch Matrices
Matrices (Basestations
(Basestations and
and Satellite
Satellite Applications)
Applications)
–– Tunable
Tunable Filters
Filters (High-Q
(High-Q Varactors)
Varactors)
–– Tunable
Tunable Networks
Networks for
for Wideband
Wideband Applications
Applications (Switched
(Switched Capacitors,
Capacitors,
Medium
Medium Q
Q needed)
needed)
•• There
There are
are currently
currently no
no high
high power
power (100
(100 mW
mW to
to 10
10 W)
W) MEMS
MEMS switches.
switches.
•• There
There are
are currently
currently no
no services
services or
or foundries
foundries for
for RF
RF MEMS
MEMS switches.
switches.