Intro to MEMS

Lecture 1:

Intro to MEMS

Dong-Il “Dan” Cho

S h l f El i l E i i d C S i School of Electrical Engineering and Computer Science, Seoul National University

Nano/Micro Systems & Controls Laboratory

Email: [email protected]: http://nml.snu.ac.kr

What is MEMS ?

• Different physics in nano and micro scales– High viscosity (> inertia) stiction friction & surface High viscosity (> inertia), stiction, friction & surface

tension are dominant in micro world

Antz, Dreamworks

Dong-Il “Dan” Cho Nano/Micro Systems & Controls Lab.This material is intended for students in 4541.844 class in the Fall of 2006. Any other usage and possession is in violation of copyright laws

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What is MEMS ?

• MicroElectroMechanical Systems

Th f b i i f d i i h l f h i • The fabrication of devices with at least some of their dimensions in the micrometer range.

• Increase performance and decrease cost• Increase performance and decrease cost.

• Application for electronics, communications, mechatronics, medicine, military, , y

• Commercial product : an accelerometer sensor for the car air-bag, an inkjet printer header, a pressure sensor, components of RF and Optics

• As a new solution for IT, BT, ET, and NT many countries investment MEMSinvestment MEMS.


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What is MEMS ?

• A brief MEMS history


4

What is MEMS ?

• Scales and dimensions


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What is MEMS ?

• Uses IC manufacturing techniques to fabricate moving structures in micro scalestructures in micro scale

(C ll)

(Http://www.analog.com)

(Cornell)


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(Http://www.analog.com)

What is MEMS ?

• Scaling law– As system becomes smaller, the scaling of the force also

d i h l i i i idetermines the acceleration, a; transit time, t; power per unit volume P/VO generated and dissipated

– the mass of a system : m, scales as (S3)– for generalized case with a force F scaling as (SF)

F

1 -2 1.5S S S⎡ ⎤ ⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥ ⎢ ⎥

for generalized case with a force F scaling as (S )– where x = distance

1

2

SS⎡ ⎤⎢ ⎥⎢ ⎥

[ ][ ]

[ ][ ][ ]( )

F -3

1

Fa = = S Sm2xm

2 -1 1

3 0 0.5

4 1 2.0

S S SF = a = t =

S S SS S S

⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⇒ ⇒⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎣ ⎦ ⎣ ⎦

3

4

SF =

SS

⎢ ⎥⎢ ⎥⎢ ⎥⎣ ⎦

[ ][ ][ ]( )1 3 -F 22xmt = = S S SF

P Fx=

-2.5

-1

S S SSSP

⎣ ⎦ ⎣ ⎦ ⎣ ⎦⎡ ⎤⎢ ⎥⎢ ⎥

O O

V tV

0.5

O

2

SP = SVS

⎢ ⎥⎢ ⎥⎢ ⎥⎣ ⎦


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What is MEMS ?

• Long slender beams are very strong in micro scale

• But moving through air in micro scale is difficult (like

Http://www.memspi.com Nano/Micro Systems & Controls Lab, SNU

swimming in molasses)


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What are MEMS driving forces ?

• MiniaturizationWearable PC

– Small feature: fast, precise, gentle, reach narrow space

• Multiplicity– Batch fabrication: mass

production, low cost– Pre-assembled system and parallel

processing: high densityIBM Millipede

• Microelectronics– Integration with electronic circuits


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MEMS Market

ld k f

Source: Inertial MEMS Markets For Consumer Electronics Applications 2007, Yole Developpement

World MEMS market forecast


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pp , pp

Intro to Micromachining

1992J of MEMS

~1995SOI process

1991IOP JMM“MEMS”

coined

1988 UC Berkley micromotor:

Beginning of

1992 ADI accelerometer

1993 Cornell

SCREAM process

1997SNU

SBM process

Multi Chip Packaging

1980 1990 2000

the surface micromaching


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Intro to Bulk Micromachining (70’s)

• Anisotropic silicon etching

Optical bench using (100) silicon Silicon tip using (111) silicon

(SNU NML)


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( )

Intro to Surface Micromachining (’85-’95)

• Typical surface micromachining process steps– In HF, oxide etches fast for sacrificial release,

substrate: (100), p- type substrate: (100), p- type

(b) nitride deposition, sacrificial oxide deposition(a) oxide/nitride deposition, polysilicon deposition & patterning& patterning

(c) anchor patterning, polysilicon deposition & (d) sacrificial wet etch in HF

substrate: (100), p-type substrate: (100), p-type

(c) anchor patterning, polysilicon deposition & patterning

(d) sacrificial wet etch in HF

(SNU MEMS MPC)


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( )


• Micro gear chain • Actuated micromirrors • Micro gear chain (four polysilicon)

• Actuated micromirrors (three polysilicon hinge structure)

(UC Berkeley, Pister Ph.D. thesis)(Sandia Lab.)


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• Aphid on mirror • 6 gears• Aphid on mirror • 6 gears

(Sandia Lab.)


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Applications – Smart Sensors

• Smart sensor– A sensor with built-in

Measuringse so t bu t

intelligence– The intelligence is partially or

fully integrated on a single chip Sensing Element

• Smart sensor architectureS i l t

Element

l nin

g

Micro&

P

– Sensing element– Interface element for signal

conditioning and data conversion

Signal

onditio

n oco

ntro

llePro

cessor

PowerEnergy

conversion– Processing element (this

includes a microcontroller with an associated memory and

Communication

Co er

r

ysoftware)

– Communication element– Power source


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Applications – Smart Sensors (cont’d)

• Trend of the smart sensors• Intelligence ↑

Signal

Conditioning &

Intelligence ↑- Self identification- Self diagnosis- Self calibration- Multi sensing

• Integration ↑- Smart sensor system- Complex systems for sensing, transforming

and signal processing

Conditioning &

Processing

Mechanical

• Miniaturization ↑- Small scale Mechanical

Thermal Chemical

- Integration- Nanotechnology

ActuatorsMulti-Sensing

Magnetic Radiant

• Performance ↑- Accuracy- Linearity- Reliability

Current Trend in Sensors &

SystemsMagnetic

Electrical

Radianty- Maintenance free • Standardization ↑

- Economies of scale- Importance of codes- Compatibility

Smarter Cheaper

Integration


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p y g


• Smart pressure sensors: piezoresistive or capacitive– Sensor + Electronics Smaller & CheaperSensor + Electronics Smaller & Cheaper– Key trends

• The growth of the medical and automotive business is stable• New application like the TPMS are boosting this marketpp g

1991Bipolar integrated ?

2010Battery less TPMS

Bipolar integrated

1999CMOS i t t d

2003Smart pressure sensor(TPMS)

?

1980

CMOS integrated(DSP)

( )

Uncompensated

1985Temperature

compensated


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• Smart pressure sensors application– Engine optimization emission control and safety enhancementEngine optimization, emission control, and safety enhancement

• Manifold intake air pressure (MAP) and barometric air pressure (BAP) for the engine control unit

• Tire pressure monitoring system (TPMS) and side airbag pressure sensor

– Medical applications• Sleep apnea, asthma monitoring, blood pressure meter

MAP sensor(Delphi)

Airbag pressure sensor(Bosch)

Wheel mounted TPMS(Siemens)

Blood pressure meter(Motorola)


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• Smart accelerometer: capacitive or thermal– Smaller devices with multiple axis sensingSmaller devices with multiple axis sensing– Key trends

• The automotive business is increasing rapidly with the growth of ESP• Consumer applications have really started use MEMS sensors in volume pp y

for application like mobile phone, GPS, and game controller

2 chip accelerometer(Motorola)

Dual-axis thermal accelerator(MEMSIC)

Capacitive accelerometer(ADI)


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• Smart gyroscope : capacitive or piezoelectric– Smaller devices with multiple axis sensingSmaller devices with multiple axis sensing– Key trends

• The ESP market is growing very fast, with adoption of the system in medium end cars. (Silicon vs. Quartz)

• GPS is another growth area, both for automotive and autonomous systems

X-axis gyroscope(SNU NML)

Z-axis gyroscope(Motorola)

iMEMS ADXRS(ADI)


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(SNU, NML) (Motorola)(ADI)


• Smart accelerometer & gyroscope applicationspp– Automotive: crash accident recording,

ESP, GPS– Consumer Electronics: video game

controller, camera image stabilization, HDD protection, mobile phone, human computer interface

Video game controller (Nintendo)

Electronic Stability Program Camera image stabilization (Sony)GPS


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y g g ( y)


• MEMS microphone– Since 2004, the industry has seen increasing sales of MEMS devices across

multiple consumer applications, with MEMS microphones for cell phones leading the pack.

– The market for overall MEMS microphones will be 432 million units in 2008, according to Yole report.g p

• MEMS microphone applications: mobile phone, PDA, digicam, camcorder, lab-top, automotive (hand-free calling)

Surface mountable monolithic digital microphone & Fabrication process for MEMS microphone (Akustica)

Silicon microphone(Knowles Acoustics)


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Fabrication process for MEMS microphone (Akustica)( )


• Smart biomedical sensors– Biomedical sensors with integrated circuitryBiomedical sensors with integrated circuitry– Implanted in the human body or wearable – Will improve people’s health, comfort and

f tsafety– Typical future sensor node

• Example applicationsp pp– Glucose level monitor– Transplant organ viability

monitormonitor– Blood monitor– Cancer detection/monitor

Hand-Held Device– Health monitor– Retinal and cortical prosthesis

Wireless Body Area Network (WBAN)

Hand-Held Device(receiver unit)


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y ( )

Applications – Fluidics and BioMEMS (cont’d)

DNA chip (Nanogen) Micromixer (Micralyne)Microfluidics (Twente)

Nanopump (De GENEVE Univ.) DNA microarray chip(Protron)

Microneedle (NML SNU)


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chip(Protron)


DNA chip (Roche)DNA chip (Roche) High through system (Caliper)

Chemical Multiplexer (Aclara) Biosensor (IMEC )


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( ) ( )


• Neural Chip - The New Bionic Man– Retina Implant– Cochlear Implant– Edinburgh Arm– Heart Assist Pump– Nose on a chip– Electronic Tongue

NCP (NeuroCybernetic Prosthesis)– NCP (NeuroCybernetic Prosthesis): relief for the epileptic seizures, VNS (Vagus Nerve Stimulation)

– Plastic muscle– Silicon Sensor

(Science, 8 February, 2002)


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(Science, 8 February, 2002)


• Cochlea prosthesis

Cochlear Inc.


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• Vision prosthesis

Extraocular Unit

Intraocular Unit

Extraocular Unit

Intraocular Unit

(http:\\www.dobelle.com) (Johns Hopkins University & North Carolina State University)


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• MEMS Neural probe

(University of Michigan) (Sung June Kim SNU)(University of Michigan) (Sung June Kim, SNU)


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Applications – OMEMS (cont’d)

• DLP(digital light processing)


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• DLP(digital light processing)

(http://www.dlp.com)


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• Microlens

Microlenses array (Axetris) Micro-Lens Scanner (UC Berkeley)


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• Optical switch

Fast on/off optical switch4×4 matrix switch for optical fiber switching Fast on/off optical switch(NML SNU)

4×4 matrix switch for optical fiber switching(Neuchatel Univ.)


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Applications – RF MEMS

• RF MEMS applications


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Applications – RF MEMS (cont’d)

• RF MEMS components for wireless devices


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• Vibrating RF MEMS devices

• Filters60-MHz wine-glass disk resonator (Michigan) Side-supported SCS disk resonator (Georgia Tech.)

Quadrature mixer-filter (Michigan) Disk array composite µMechanical filter (Michigan)


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Quadrature mixer-filter (Michigan) Disk array composite µMechanical filter (Michigan)


• MEMS switch

• InductorZipper-Actuated RF MEMS switch (MIT) Single crystalline silicon RF MEMS switch (SNU)

Solenoid inductor (LG) 3-D microstructure for RF MEMS (KAIST)


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Solenoid inductor (LG) 3 D microstructure for RF MEMS (KAIST)


• Non-Contact-Type RF Switch (SNU)– Free from welding and stiction problemsee o e d g a d st ct o p ob e s– RF characteristics of non-contact-type switch

• Insertion loss = 0.29 dB @ 24 GHz• Isolation = 34.5 dB @ 24 GHzIsolation 34.5 dB @ 24 GHz

Off-state signal flow

On-state signal flow

The complete view of the switch

signal flow

The magnified view of the variable capacitors


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Documents

Intro to MEMS