Microelectromechanical Systems (MEMS) Actuators

© October 31, 2016 Dr. Lynn Fuller

Rochester Institute of Technology

Microelectronic Engineering

MEMs –Actuators

ROCHESTER INSTITUTE OF TEHNOLOGYMICROELECTRONIC ENGINEERING

October 31, 2016 MEM_Actuators.ppt

Microelectromechanical Systems (MEMS)

Actuators

Dr. Lynn Fuller and Dr. Ivan Puchades

Webpage: http://people.rit.edu/lffeeeMicroelectronic Engineering

Rochester Institute of Technology82 Lomb Memorial Drive

Rochester, NY 14623-5604Tel (585) 475-2035

Email: [email protected] Dept Webpage: http://www.rit.edu/kgcoe/microelectronic

http://people.rit.edu/lffeee

mailto:[email protected]

http://www.rit.edu/kgcoe/microelectronic




MEMs –Actuators

INTRODUCTION

Actuators

ThermalTwo beam heated cantileverPolyimide on HeatersBimetalicheaters on diaphragms

ElectrostaticCapacitor Plate DriveComb Drive

OtherElectromagneticPeizoelectric




MEMs –Actuators

OUTLINE

Polycrystalline Silicon Thermal ActuatorsChevron ActuatorsHeated Diaphragm ActuatorsHeated Polyimide Cantilever MirrorsPolyimide Thermal Actuators

A Walking Silicon Micro-RobotThermal Mirrors

Electrostatic ForceDigital Light Projection

Electrostatic Impact-Drive MicroactuatorShuffle Motor

Electrostatic Comb DriveMagnetic Actuators on a Diaphragm




MEMs –Actuators

POLYCRYSTALLINE SILICON THERMAL ACTUATORS

Polycrystalline Silicon Thermal Actuators Integrated with Photodetector

Position Sensors

Kevin Munger




MEMs –Actuators


No current flow




MEMs –Actuators


Current flow




MEMs –Actuators

SELECTED MATERIAL PROPERTIES

Thermal Young’s Thermal DensityExpansion Modulus Conductivityppm/°C 1012 dyne/cm2 w/cmK gm/cm3

Silicone Elastomers 275-300 Unfilled Epoxies 100-200 0.015Filled Epoxies 50-125Aluminum 20-25 0.68 2.36 2.7Copper 15-20 1.20 3.98 8.96Gold 14.2 0.785 3.19 19.3 Silicon (single crystal) 2.4 1.9 1.9 2.33Poly Silicon 2.4 1.5 1.5 2.33Inconel 2.4Nickel-Iron 1.22Alumina Ceramic 6.3Borosilicate Glass 5.0Silicon Dioxide 0.55 0.73 0.014 2.19Silicon Nitride 0.8 3.85 0.185 3.44Diamond 1.0 11 20Air - - 0.00026Water - - 0.0061

10 dyne/cm2 = 1 newton/m2




MEMs –Actuators

THERMAL EXPANSION

1. How much will a 500 um long bar of aluminum expand if it is

heated 200 C above ambient?

DL/L = 22 ppm/C

= 22 x 200 = 4400 ppm = 4400E-6

DL = 4400E-6 x 500 um = 2.2 um

2. If the hot arm on a 200µm Si actuator is 400C hotter than the cold

arm how much longer will it be ?

DL/L = 2.4 ppm/C

= 2.4 x 400 = 932 ppm = 960E-6

DL = 960E-6 x 200 um = 0.192 um




MEMs –Actuators

FINITE ELEMENT ANALYSIS OF THERMAL BENDING

Small arm 400 C, 10um X 200 um

Large arm 0 C, 30 um x 200 um

Maximum Displacement = 0.12 um




MEMs –Actuators

FEA SIMULATION




MEMs –Actuators

INTEGRATION OF PHOTODIODE AND MEMS

December 2001Kevin Munger. joinedIBM Burlington, VT

Maximum Deflection 9 µm at 30 µw

162,000 cycles, 6 msec.,

Thermal Actuator with

Integrated Photodiode




MEMs –Actuators


Summary

These devices give large mechanical motion

on the order of several to few 10’s of micrometers

These devices are analog

Integrated with analog photodiode position detection

can give feedback for accurate position

Cycle fatigue seems to be infinite




MEMs –Actuators

CHEVRON ACTUATOR

1000um10° Angle

Thermal Expansion for Si is 2.33E-6/°C

Current flow causes heating and movement




MEMs –Actuators

CHEVRON ACTUATOR

1000um10° Angle




MEMs –Actuators

MODIFIED BULK PROCESS FOR MEMS CLASS 2004-06

Thermopile

Inductor

Accelerometer

Pressure Sensor

Speaker

Movie




MEMs –Actuators

DIAPHRAGM

Diaphragm:

Displacement

Uniform Pressure (P)

Radius (R)

diaphragm

thickness ()

Displacement (y)

E = Young’s Modulus, = Poisson’s Ratio

for Aluminum =0.35

Equation for deflection at center of diaphragm

y = 3PR4[(1/)2-1]

16E(1/)23= (249.979)PR4[(1/)2-1]

E(1/)23

*The second equation corrects all units

assuming that pressure is mmHg,

radius and diaphragm is m, Young’s

Modulus is dynes/cm2, and the

calculated displacement found is m.




MEMs –Actuators








MEMs –Actuators

CALCULATOR FOR DIAPHRAGM DEFLECTIONS

Rochester Institute of Technology 5-Apr-06

Dr. Lynn Fuller Microelectronic Engineering, 82 Lomb Memorial Dr., Rochester, NY 14623

Deflection Ymax = 0.0151 P L4(1-Nu2)/EH3 Ymax = 0.17 µm

P = Pressure P = 15 lbs/in2

L = Length of side of square diaphragm L = 1000 µm

E = Youngs Modulus E = 1.90E+11 N/m2

Nu = Poissons Ratio Nu = 0.32

H = Diaphragm Thickness H = 35 µm

P = 1.03E+05 Pascal

Stress = 0.3 P (L/H)2 (at center of each edge) Stress = 2.53E+07 Pascal

P = Pressure Yield Strength = 1.20E+10 Pascal

L = Square Diaphragm Side Length

H = Diaphragm Thickness

Capacitance = eoer Area/d C = 7.97E-11 F

eo = Permitivitty of free space = 8.85E-14 F/cm

er = relative permitivitty = 1 for air Area = 9.00E-02 cm2

Area = area of plates x number of plates N = 1

d = distance between plates d = 1 µm

If round plates, Diameter = 0 µm

If square plates, Side = 3000 µm




MEMs –Actuators

CALCULATOR FOR DIAPHRAGM DEFLECTIONS

Rochester Institute of Technology 11-Feb-14

Dr. Lynn Fuller Microelectronic Engineering, 82 Lomb Memorial Dr., Rochester, NY 14623

To use this spread sheet enter values in the white boxes. The rest of the sheet is protected and should not be

changed unless you are sure of the consequences. The results are displayed in the purple boxes.

Diaphragm

Deflection Ymax = 0.0151 P L4(1-Nu2)/EH3 Ymax = 9.44E-03 µm

P = Pressure P = 1.50E-05 lbs/in2

L = Length of side of square diaphragm L = 20000 µm

E = Youngs Modulus E = 1.90E+11 N/m2

Nu = Poissons Ratio Nu = 0.32

H = Diaphragm Thickness H = 50 µm

P = 1.03E-01 Pascal

Diaphragm

Stress = 0.3 P (L/H)2 (at center of each edge) Stress = 4.96E+03 Pascal

P = Pressure Yield Strength = 1.20E+10 Pascal

L = Square Diaphragm Side Length

H = Diaphragm Thickness 1N/m2 = 1Pascal = 10dyne/cm2

Two Parallel Plates

Capacitance = eoer Area/d C = 5.5549E-11 F

eo = Permitivitty of free space = 8.85E-14 F/cm

er = relative permitivitty = 1 for air Area = 3.14E+00 cm2

Area = area of plates x number of plates N = 1

d = distance between plates d = 50.026 µm

If round plates, Diameter = 20000 µm

If square plates, Side = 0 µm

Capacitance Change for Ymax Deflection = 1.05E-14 F

Two Parallel Plates

Electrostatic Force= eoer Area V2/2d2 Felec = 1.39E-05 N

V = applied voltage V = 5 volts

Single Plate

Pressure Force = Pressure x Area Fpress = 4.14E-05 N

Single Plate with a Coil in a Magnetic Field Approximate Equation 1

Electromagnetic Force = I L B Fmagnetic = 1.88E-03 N

Assuming a constant field strength B from a Rmax of Coil = 1000 µm

permanent magnet then, Lorentz Force = I L B Rmin of Coil = 500 µm

where I is the current in a coil of length L, Number of turns (N) = 40 turns

L =~ 2 pi Rave x N, Rave = (Rmax+Rmin)/2 Length of coil (L) = 1.88E-01 m

Current (I) = 0.02 amperes

Magnet Field Strength (B) = 0.5 Tesla

Single Plate with a Coil in a Magnetic Field Approximate Equation 2

Electromagnetic Force =

distance between magnet and coil = 300 µm

radius of coil = 750 µm

radius of magnet = 2000 µm

Fmagnetic = 3.70E+00 N

Cheng eq. 6-196

Resonant Frequency of Round or Square Diaphragm =

Dd is diameter or length of diaphragm Dd = 3 mm

Ey is youngs modulus Ey = 1.9 x1012 dynes/cm2

Td is diaphragm thickness Td = 20 µm

Nu is Poisons ratio Nu = 0.32

Rho is volumn density Rho = 2.33 gm/cm3

fo is 1st resonant frequency for round fo = 39559 Hz

fo is 1st resonant frequency for square fo = 35999 Hz

Diaphragm Volumn = 0.0001413 cm-3

Diaphragm Mass = 3.E-04 gm

AddedBio Mass = 4 gm x 10-9

Delta Rho = 2.83086E-05 gm/cm3

Delta fo = 0 Hz

Resistive Bridge Output

Film Sheet Resistance Rhos = 61 ohms/sq

Resistor Length L = 350 um

Resistor Width W = 50 um

Nominal Resistor Value R=Rs L/W R = 427 ohms

Strain = Stress/Youngs Modulus e = 0.000 %

Deflection for given pressure

Stress at edge of diaphragm

Electrostatic equivalent pressure

Magnetic equivalent pressure

Resonant frequency

Piezoresistive bridge calculations




MEMs –Actuators

ANSYS FINITE ELEMENT ANALYSIS

Regular Si Diaphragm Corrugated Diaphragm

Layer 2: 1.5mm x 1.5mm Polysilicon 1μm thick

2mm x 2mm diaphragm 30µm thick, 50 psi applied

Rob Manley, 2005




MEMs –Actuators

DIAPHRAGM DEFORMATION MOVIE

Rob Manley, 2005

200µm




MEMs –Actuators

PICTURES OF WAFER AFTER KOH ETCH

50 µm in 57 min ~.877 µm/min




MEMs –Actuators

DIAPHRAGM THICKNESS USING OPTICAL MICROSCOPE

20% KOH Etch, @ 72 C, 10 Hrs.

31 µm500 µm




MEMs –Actuators

SQUARE DIAPHRAGM MOVIE




MEMs –Actuators

MEMS THERMAL ACTUATOR AND POSITION SENSOR




MEMs –Actuators

THERMAL ACTUATED VERTICAL DISPLACEMENT

Veeco NT1100Increase heater currentMeasure z-displacement and Vout

Ih e a t (m A ) V o u t (m V ) Z -d e f le c t io n (u m ) v e c c o

0 1 1 .8 -4

2 0 1 1 .3 -2 .7 5

3 0 1 0 .6 -1 .6

4 0 8 .7 -0 .6 5

5 0 6 .2 0 .3 5

6 0 1 .3 2 .6 5

6 6 -1 7 .4 1 7 .5

7 0 -2 1 .7 2 2 .2

y = - 1 .3 4 1 9 x + 7 .0 0 2 8

R2 = 0 .9 9 1 8

- 1 5

- 1 0

- 5

0

5

1 0

1 5

- 5 0 5 1 0

Z - d e fle c tio n (µm )

Vo

ut

(m

V)




MEMs –Actuators

VISCOCITY SENSOR JOURNAL PUBLICATION AND PATENT




MEMs –Actuators








MEMs –Actuators

POLYIMIDE ON HEATER

Movie




MEMs –Actuators

A WALKING SILICON MICRO-ROBOT




MEMs –Actuators


http://www.s3.kth.se/mst/staff/thorbjorne.html

Professor Goran Stemme

Kungliga Tekniska Hogskolan

Stockholm, Sweden

http://www.s3.kth.se/mst/staff/thorbjorne.html




MEMs –Actuators





MEMs –Actuators


Movie




MEMs –Actuators

THERMALLY ACTUATED MICRO MIRROR




MEMs –Actuators

CAPACITIVE ELECTROSTATIC FORCE

F

++++++++

- - - - - - -

The energy stored in a capacitorcan be equated to the force timesdistance between the plates

W = Fd or F = W/d

2d2

eo e r AV2F =

d

area A

Energy stored in a parallel plate capacitor W

with area A and space between plates of d

W = 0.5 QV = 0.5 CV2

since Q = CV

d

e oe rAC =

e opermitivitty of free space = 8.85e-12 Farads/m

e r = relative permitivitty (for air e r = 1)




MEMs –Actuators

ELECTROSTATIC FORCE EXAMPLE

Example: 100 µm by 100 µm parallel plates

space = 1 µm, voltage = 10 V

Find the force of attraction between the two plates

e oe r AV2

F =2d2

8.85e-(100e-6)(100e-6)(10)2

F =2(1e-6)2

F = 4.42e-6 newtons




MEMs –Actuators

DIGITAL LIGHT PROJECTION SYSTEM

www.TI.com

http://www.ti.com/




MEMs –Actuators

TI DLP - ELECTROSTATIC MIRRORS

www.TI.com

Torrisonal Mirrors Can Tilt

Along One Axis

http://www.ti.com/




MEMs –Actuators

ELECTROSTATIC MIRROR

MOEMs - Micro Optical Electro Mechanical Systems

Lucent Technologies–Lambda Router (256 mirror fiber optic multiplexer)

Nested Torrisonal Mirrors Can Tilt Along Three Axis




MEMs –Actuators

ELECTROSTATIC IMPACT-DRIVE MICROACTUATOR




MEMs –Actuators


1. Actuator can generate high

power

2. Maintain a position precisely

3. Move a long distance.




MEMs –Actuators





MEMs –Actuators


Testing

Figure shows test resultsfor 1Hz actuation, each impactgives 20 nm displacement

Lifetime looks good. Testfor 1 month, 550 million collisions, no visible problems

Energy was supplied to actuator by wireless RF transmision




MEMs –Actuators





MEMs –Actuators


Conclusion

A New type of actuator is described

Diven by electrostatic force

~15 nm per impact at 100 Volts

Speed of 2.7 um/sec at 200 Hz

Life greater than 550 million impacts




MEMs –Actuators

MEMS SWITCH

Electrostatic actuation (V) pulls down contactor to make connection along the signal line.

V

Signal LineSignal Line

Signal Line Signal Line




MEMs –Actuators

SWITCH CALCULATIONS PLUS DIMENSIONS

Each project has 5mm x 5mm layout space

Artur

Nigmatulin

2011




MEMs –Actuators

AC MEMS SWITCH




MEMs –Actuators

SHUFFLE MOTOR MOVIES

What actuation mechanism is this?

Movie Movie




MEMs –Actuators

ELECTROSTATIC COMB DRIVE MICROACTUATORS

Electrostatic movement parallel to wafer surface

AnchorAnchor

Anchor

From Jay Zhao




MEMs –Actuators

CALCULATION OF DISPLACEMENT VS VOLTAGE

t

L

d

movement

F = er eo t V2 / 2 d




MEMs –Actuators

SPRING ELECTROSTATIC DRIVE & CAPACITIVE READ OUT

Anchor

C1

C2

C1

C2

Anchors

and Electrical Ground

Gnd




MEMs –Actuators

PICTURES & MOVIES OF ELECTROSTATIC COMB DRIVE

Movies at www.sandia.gov

http://www.sandia.gov/




MEMs –Actuators

PICTURES & MOVIES OF ELECTROSTATIC COMB DRIVE

MOVABLE MIRROR

Movies at www.sandia.gov

http://www.sandia.gov/




MEMs –Actuators

MAGNETIC TORSIONAL MIRROR

W

Contact

L

Supporting arm

z

Bcoil

Bm

Figure 2: Cross sectional view labels with

variables.

Nz

BLW

Rz

IR

z

mmF

o

m

o

coilm

2

2/322

2

02

4

Metal contact

Topside Hole

Diaphragm

Figure 1: Top down CAD design of single axis

Torsional Mirror

Paper by Eric Harvey




MEMs –Actuators

MAGNETIC FIELD

Bi

F




MEMs –Actuators

DARTMOUTH COLLEGE MICROROBOTS

This SEM image shows the untethered scratch drive actuator (A) used for propulsion, and the cantilevered steering arm (B)which can be lowered to provide a turning pivot. The wavey lines the robot sits on are the insulated interdigitated electrode array which transmits power and control signals to the robot.

http://engineering.dartmouth.edu/microeng/robot05.html




MEMs –Actuators

REFERENCES

1. “Microsensors,” Muller, Howe, Senturia, Smith and White, IEEE Press, NY, NY 1991.

2. “Sensor Technology and Devices,” Ristic, L.J., Artech House, London, 1994.

3. IEEE Journal of Microelectromechanical Systems4. “Electrostatic Impact-Drive Microactuator”, M.Mita, et.el.,

University of Tokyo, IEEE, 20015. “A walking Silicon Micro-Robot”, Thorbjorn Ebefors, et.el.,

Department of signals, sensors and Systems, Royal Institute of technology, Stockholm, Sweden, 10th Int. conference on solid-State Sensors and Actuators, Sendai Japan, June 7-10, 1999.

6. MEMs Wing Technology for a battery-Powered Ornithopter, T. Nick Pornsin-sirirak, Caltech Micromachining Laboratory, Pasadena, CA, 91125, IEEE, 2000.

Microelectromechanical Systems (MEMS) Actuators

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