MEMS-Application, Functionality, Fabrication process and limitations, MEMS as a switch, MEMS packaging and proposed mems switches for microwave circuit switch.

1. 1
Presentation by
Tonmoy Ibne Arif (35177946)
Masters in ElectricalCommunication Engineering
RF MEMSBASIC

2. Outline
2
RF MEMS BASIC
o What is MEMS ?
o Size Comparison ?
o MEMS VS IC
o Features of MEMS
o Where it Began
o Popularity of Mems
o Market Potential
o Fabrication of MEMS
o Material Used for MEMS
o MEMS Packaging
o Why MEMS
o Applications
o What is RF MEMS
o Why RF MEMS
o Application & Market Pontential of RF MEMS
o RF MEMS Switch
o Ohmic cantilevertype RF-MEMS micro-switch
o Shunt type ohmic RF MEMS switch
o RF MEMS Ohmic Switch
o Pros Of Ohmic & Shunt Switches
o RF MEMS Capacitor
o Electrostatically controlled RF-MEMS
device
o Capacitive RF MEMS switch
o RF-MEMS PASSIVE COMPONENTS
o Application of Capacitive RF MEMS
switch
o Advantages RF MEMS Switches over SSS
o RF MEMS Devices
o RF MEMS variable Capacitor
o RF MEMS Tunable Inductor
o MEMS Phase Shifters
o Commercial MEMS Switch
o RF MEMS Limitations
o Summary
o References

3. What is Mems?
.
Micro-Electro-Mechanical Systems are known as MEMS. MEMS refers to
miniature mechatronic systems.Where we integrate sensors,actuators, and
other electronic elements.Other techniques are also available like
deposition,patterning, and etching.The integration process is generally done
on a common silicon substrate using micro-fabrication technology. [1]
Some commercial MEMS:
3
RF MEMS BASIC
[2]Figure 1: Commercial MEMS

4. Size Comaprison
.
4
RF MEMS BASIC
[4]
Figure 2: Biological & Techonological Scale comparison.

5. MEMS vs IC
.
5
RF MEMS BASIC
[2]
MEMS
• 3D structures
• Sometimes have moving parts
• No building block
• Pacakaging is a very complex
process.
• May have interface with
external media
• Can be used for
biological,Chemical and many
more
ICs
• 2D structures
• No moving parts available
• Always have basic building block
• Well developed packaging
techniques are available.
• Only conected with internal
circuit
• Only Electrical

6. MEMS Component
Figure: Accelerometer Gyroscope[21]
6

7. MEMS Component
Figure: MEMS Magnetometer [ 21]
7

8. Features of MEMS
MEMS are used for Sensing,Actuation (passive micro-
structures)
• Cost reduction
• Increase functionality
• Improve reliability
• Small in size: In the range of micrometer to Milimeter
• Techniques and processes to design and create
miniature systems Miniature embedded system
• Fewer defects per chip
• Reduce noise and improve sensitivity.
. RF MEMS BASIC 8
Figure 3: Component of MEMS [1]
[1]

9. Where it Began
➢ Point Contact Transistor invented in 1947 by Bardeen,Bratitan.Schockly
➢ 1959 First silicon pressure sensor demonstrated(Kulite)
➢ Surface Micromachinig Process was first introduced in 1968.
➢ 1971 the first microprocessor was invented.
RF MEMS BASIC 9
Figure 4:First Commercial Processor by Intel [ 5]
[ 5]

10. Popularity of MEMS
RF MEMS BASIC 1
0
[ 1]
Many famous brands are now using MEMS in their products for various purposes .
Wii and iPhone using MEMS to detect motion and changes in orientation.
Wii- instead of using the joystick, Wii players can move their arms & body to simulate
an action, like playing Mortal Kombat.
iPhone-unique feature is it able to rotate an image with the rotation of the
phone.(Recently iPhone 6 has replaced it,s solid state switch with RF MEMS Switch)
Texas Instrument-DLP chip, which is mainly used in projectors and TV projections.
Airbags-BOSCH is using the accelerometer to detect hard deceleration .
Automobiles Tires-Infineon introduces Pressure Sensor MEMS chips which enable us
to get notification low air pressure in w Vehicle Tire.
Laptops and Cellphones- MEMS are used to capture the sound and convert it into to
a digital signal on the same chip.
Digital Camera- Nowadays Analog Gyroscope is made based on MEMS and which
help us to adjust between portrait and landscape mode.

11. Market Potential
11
RF MEMS BASIC
Source: Semico Research Corp. (Phoenix, Ariz.) [ 6 ]

12. FabricationProcessof MEMS
12
RF MEMS BASIC
Fabrication Of MEMS
Physical
Deposition Etching
Chemical
Lithography
Dry
Wet
Pattering
Photolithography
321

13. FabricationProcessof MEMS
• Deposition:-
Deposition of thin flim.It is usually ecthed to remove unwante dmaterial and leave the
desired pattern on the waffer.Diposition that happens because of Chemical reaction or Physical
reaction
• Patterning:-
-Transfer to a photosensitive material, exposure to UV light.
-Developed in solution after exposure to UV.
-Material Etch away.
• Ecthing
-In this process acid is used to disolve unprotected parts of metal surface to creat a design.
Here we use
i.Dry
ii.Wet
13

14. FabricationProcessof MEMS
14
RF MEMS BASIC
Deposition Etchin
Chemical
Lithography
Dry
Pattering
Photolithography
Figure 5 :Steps of LIGA process to fabricate high aspect ratio MEMS devices
(LIGA is a
HARMST
process)
[ 1]

15. Materialsusedfor MEMS
15
RF MEMS BASIC
➢ Metals-Gold,Ni,Al,Cr,Pl and Ag
➢ Polymers
➢ Ceramic materials
➢ Semiconductors-Silicon
➢ Composite Materials
[ 1]

16. MEMS Packaging
16
RF MEMS BASIC
Function of a package is to integrate all of the component required for a system application
in a manner that minimize size,cost,mass and complexity.It provides the interface between
the components and the overall system.
Three main functions of the MEMS package
I. Mechanical support
II. Protection from the environment
III. Electrical connection to other system components.
Types of MEMS Packages:
I. All Metal packages
II. Ceramic
III. Plastic
IV. Thin-film multilayer packages.
[ 1]

17. MEMS introduced many benefits of size reduction on the electrical domain :
Why MEMS…?
17
RF MEMS BASIC
❑ Speed –High Frequency,Low Thermal time
const.
❑ Power Consumption-less Actuation Energy
& Heating power.
❑ Complexity- High Integration density &
functionality.
❑ Faster switching
❑ Low loss
❑ Larger networks
❑ Fast Analysis speed
[ 1]

18. Apllications
18
RF MEMS BASIC
Figure 6: Apllication fiields of MEMS(Source - Università del Salento) [ 7]

19. “RF mems devices are microsystems manufactured in a suitable techonology platform,
typicall characteristic by having movable micro-parts capable of reconfiguring the rf
chracteristic of a device “. [ 8 ]
Features of RF MEMS :
• High Quality
• Three Dimensional
• Microscale Structure
What isRFMEMS ?
19
RF MEMS BASIC
Figure 7: MEMS Package [ 9 ]

20. ➢ Small in size
➢ High Shock resistivity
➢ Require less power to operate
➢ Can operate within a wide temperature range
➢ Minimum weight
➢ High linearity
➢ Can operate within large frequency bandwidth
➢ It is easy to alter parts of MEMS device compare to other counterpart.
➢ Automotive industries are widely using RF MEMs
(To measure tire air pressure,Fuel pressure and Lubricant Oil pressure)
➢ It is the house of both mechanical and electrical components in microscale.
Why RFMEMS?
20
RF MEMS BASIC

21. [10]
21
RF MEMS BASIC
Applications & Market Potential of RF MEMS

22. 22
RF MEMS BASIC
Properties :
• Operates at low volatge.(less than 1 volt)
• Less susceptible to high power.
• Due to bistability of the actuators no standing power is consumed .
• No parasitic inductance effect.
RF MEMS SWITCH
Figure 8: Schematic diagram of the RF MEMS switch at On-state & off-state
[ 11 ]

23. 23
RF MEMS BASIC
Ohmic cantilevertype RF-MEMS micro-
switch
Figure 9:Schematic cross-section of an ohmic cantilever- type RF-MEMS micro switch
a) No bias is applied (OPEN).
b) The Relay is closed after applying suitable voltage level.
[ 12]

24. 24
RF MEMS BASIC
Shunt type ohmic RF MEMS
switch(Proposed)
Figure 10:A schematic diagram of shunt type ohmic RF MEMS switch with piezoelectric actuation.
Figure 11:Equivalent circuit model of shunt type ohmic RF MEMS switch: on and off states. [ 12]

25. 21
RF MEMS Ohmic Switch
[8]
•Low insertion loss.(10GHz-
0.27db)
•High Isolation
•High Linearity
•Gate voltage can vary from
40-120 volt depending on the
design.
RF MEMS BASIC
Figure 12: SEMimage of Ohmicswitch.
Figure 13:Schematic representation of Ohmicswitch.Properties of Ohmic switch:
• Operates for both DC and RF
application
• The micrp switch have trhree terminals
• Can operate in high temperature
environment.
• Operate upto 60GHz

26. Pros Of Ohmic & Shunt Switches
[8]
RF MEMS BASIC
Ohmic Switch:
• Very Low Insertion loss
• Very high off state isolation
• Low power consumption
Shunt Switch:
• Long life time
• Independent from contact force.
• Low On state insertion loss.
• Super tolerance for higher
temperature envieronment.
22

27. RF MEMS Capacitor
[8]
RF MEMS BASIC
23
The Capacitor is used in RF MEMS are usually variable capacitors. The capacitance can
be tuned by changing either area and the distance between the plates or the dielectric
constant.
According to Their tunning parameter, Mems can be categorized MEMS
❑ GAP-Tunning Capacitor
❑ MEMS AREA-Tunning Capacitor
❑ MEMS Dielectric-Tunning Capacitor
Gap tuning capacitor can be made using two parallel plates . The upper is connected to
a spring and is movable and the lower part remained fixed.
The gap between the electrodes can be changed by applying a dc voltage to the
electrodes. Where displacement=applied voltage.

28. 28
RF MEMS BASIC
Electrostatically controlled RF-MEMS
device
Figure 14:One dimensional schematization of an electrostatically controlled RF-MEMS
device (massspring and parallel plate capacitor)
(a) Rest position.
(b) Equilibrium position.
(c) Actuated position.
[ 12 ]

29. 29
RF MEMS BASIC
Capacitive RF MEMS switch
Figure 15:Schematic of shunt capacitive
type RF MEMS switch
Figure 16:Functions of shunt capacitive type RF
MEMS switch.
• Electrostatic actuation method
• Variable capacitance can be obtain by
providing dc bias
• Capacitance detemined by sapcing
• Isolation depend on capacitive ratio
between On and OFF state.
• Switch consistsof a metallic electrode
• Voltage isapplied between the suspended
electrode
[ 13]

30. 30
RF MEMS BASIC
RF-MEMS PASSIVE COMPONENTS
Figure 17:clamped-clamped RF-MEMS.
Figure 18:Holes in the metal needed for technology purpose.
Scanning Electron Microscopy(SEM) photograph of a clamped-clamped RF MEMS
• Double Hinged
• Electrostatically controlled device
used in Coplanar waveguide
configuaration(CPW)
• Sacrificial layer is removed.
[ 14]

31. 31
RF MEMS BASIC
RF-MEMS PASSIVE COMPONENTS
Figure 20 : S11 parameter(reflection).
Figure 21:S21 parameter(transmission/isolaton).
• S11 is High,RF power is
reflected(OPEN switch)
• S21 is low at Isolation.But
Small losses (Closed switch )
[ 14]

32. 32
RF MEMS BASIC
Application of Capacitive RF MEMS switch
• Telecommunication
• Aerospace and defense system
• Automotive system
• Low-voltage capacitive shunt microsystem
• Cmos compatible
Advantages.
• Longer contact lifetime
• Broad frequency coverage
• Insertion loss dependent on the contact resistance
• High switching speed(5-100microseconds.The actual time that it take to move
the membrane is in most cases probably less than 1 microsecond)
[ 1]

33. Advantages RF MEMS Switches over SSS
33
RF MEMS BASIC
• Very low Power Consumption (0.5-1mW)
• Higher power Handling Capability.
• Very High Isolation
• Very Low Insertion Loss
• High Linearity
• Better stability with temperature
• Multiple frequency range (DC to max frequency)
• Potential for Low Cost
• Fast switching capability (1-300uS)
• ESD Imuunity is High.
[ 1]

34. Applications RF MEMS Switches over SSS
34
RF MEMS BASIC
• Industrial Instruments
• Medical Instruments
• Cellular Phones
• Transmitter and receivers
• Low frequency applications
• Automatic test equipment
• Satelite Communication
• Phase shifter
[ 1]

35. RF MEMS Devices
35
RF MEMS BASIC
Many of the RF component now has been replaced by MEMS
technology
I. MEMS Variable capacitor
II. MEMS Tunable Inductor
III. MEMS Phase Shifter
IV. MEMS Multiport Switch
[ 1]

36. RF MEMS variable
Capacitor(Proposed)
[15]
• It consists of two parallel plates
• Four T shaped beams
•Air is between the top plate and bottom
plate
•When voltage is to the pads, the top
plate moves downard because of
electrostatic force
•50% capacitance increases
36
RF MEMS BASIC

37. 33RF MEMS BASIC
[16]
RF MEMS Tunable Inductor
An inductor is capable of inducing a voltage with time-varying
current
• It stores magnetic energy.
• It is a coil of wires in spiral or circular shape.
But the use of wire in macroscopic scale affects the circuit
• Capacitance and resistance along with the inductance
• The signal can be delayed due to these parasitic effects.
• Noise is generated due to the resistance
• Insertion loss is increased

38. 34RF MEMS BASIC
[10]
RF MEMS Tunable Inductor
A micro scale version of inductor implies minimized values of parasitic elements.
Proposed structure of avariableinductor.
Structure of an improved heatexpansion
actuator.
When currentflows andheat isgeneratedin the lower metal,
the tip portion goesup.
[17]

39. 39
RF MEMS BASIC
[18]
MEMs switch scan can be used as phase shifters by switching
between two different signal paths. MEMS phase shifter generally
uses in phase arrays where multiple antennas are fed by single input
power. A phase shifter is a two-port network which has the ability to
control the phase difference between the input and output power
Phase Shifter is of two types:
I. Digital Phase Shifter
II. Analog Phase Shifter
MEMS Phase Shifters

40. Multi-stag Linear-codedphaseshifters
Properties:
•Total phase-shift of 360° ,
•It,s phaseresolutionof 45° can be
obtained by the distance between
each stage 10um.
•45° phase- shift steps can be
achieved by placing seven single
45° stages in series.
[13]
40
RF MEMS BASIC
[19]

41. 37
MM3100 Switch Developed by MenloMicro
Properties:
I. 6 channel mems switch
II. DC to 3GHz frequency range
III. Low Insertion loss<0.3db @3GHz
IV. Low on state resistance<0.75 ohm.
V. High reaibility
VI. Switching time <10us
Commercial MEMS Switch
RF MEMS BASIC
Figure 22: MM3100 MEMS Switch
Figure 23:Schematic representation of MM3100
[20]

42. 42
RF MEMS BASIC
RF MEMS Limitations
• The active device requires power.
• Very Low noise response at low frequency (<1Hz) because of
the small mass of it.
• Due to their size, significant power transfer is impossible.
• Complex Manufacturing process.
• Switching speed is relatively slow(2-40us)
• Due to its base material cannot be loaded with a large load.
• Lifetime is less(MEMS 0.1~40 Billion cycles)
• Humidity effect is a serious issue for MEMS structures.
• Vibration and Shock
[1]

43. RFMEMSLimitations
[1]
43
RF MEMS BASIC
Packaging Problem
• MEMS packaging is more challenging than IC packing
• MEMs devices need to be simultaneously in contact with the
environment and as well as protect from the environment .
• Different packaging method is required for different MEMS-
according to field of usage and properties .
• Due to expansion coefficient of metals(which is 10 times higher
than silicon), It is a problem to use metal packaging
(As there are three packaging techniques is available )
• To prevent package expansion, special isolation techniques is
required.
• Currently, the cost of MEMS packing typically account for 75% or
more of the sale price of the device

44. summary
44
RF MEMS BASIC
•As there are MEMS is a Promising Technology for the 21st century.
•Currently, the packaging is a significant portion of the total cost of
MEMS device. So more research should be done on packaging to
reduce the manufacturing cost. Need to increase resources for
designing, prototyping & manufacturing devices. (Few organizations
willing to do it because of huge cost )
• MEMS fabrication demands clean room technology. MEMS fabrication
requires very specialized skills and practical experience with innovative
engineering skill.

45. References
45
RF MEMS BASIC
1. https://www.mems-exchange.org/MEMS/what-is.html
2. https://www.quora.com/What-is-the-difference-between-an-IC-and-a-MEMS
3. Julian W. Gardner, Microsensors: Principles and Applications, Wiley 1994, ISBN 0-4719-4135-
4. https://de.wikipedia.org/wiki/Datei:Biological_and_technological_scales_compared-en.svg
5. http://scmenm.org/index.php?option=com_docman&task=cat_view&gid=63&Itemid=53
6. http://www.semi.org/en/node/39781
7. Chris Reeves (QINETIQ), ‘Metrology and reliability challenges facing the fabrication of Microsystems Technologies Advanced
Microsystems’, DTIP Stresa, Lago Maggiore, Italy 25 April 2006
8. http://www.me.iitb.ac.in/~gandhi/me645/05L1_coursecontents_mtvn.pdf
9. https://www.google.com/search?q=mems+package&client=firefox-
b&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiu2qDk9arbAhUqSJoKHQdhDrgQ_AUICigB&biw=1366&bih=636#imgrc=zfifr
QYIIjh3ZM:
10. 1. Gabriel M. Rebeiz, RF MEMS: Theory, Design, and Technology, John Wiley & Sons, Inc. New York, NY, USA , 2003, ISBN:0471201693.
11.http://www.ece.lsu.edu/dyhah/RF_switch.html
12.https://www.researchgate.net/figure/Schematic-cross-section-of-an-ohmic-cantilevertype-RF-MEMS-micro-switch-a-The-relay-
is_fig2_262406936
13.http://tempest.das.ucdavis.edu/mmwave/mems.html
14.https://www.researchgate.net/figure/SEM-photograph-of-an-RF-MEMS-variable-capacitor-or-capacitive-switch-The-
suspended_fig6_257303364
15.https://www.sciencedirect.com/science/article/pii/S0026269207002455
16.Mems Tunable Inductors: A SurveyMir Majid Teymoori and Jaber Merrikhi Ahangarkolaei
17.http://www.el.gunma-u.ac.jp/~kobaweb/news/pdf/AVLSIWS2005.pdf
18.RF MEMS Phase Shifters and Their Applicationin Phase Array AntennasMaximilian C. Scardelletti, George E. Ponchak, Afroz
J Zaman, and Richard Q. Lee
19. http://www.diva-portal.org/smash/get/diva2:516789/FULLTEXT01.pdf
20. https://www.menlomicro.com/rf-tuning-products.html
21. https://www.youtube.com/watch?v=oLELDb94kzM

46. Thank You