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1 Technology Platforms for Micro-Nanoelectromechanical Systems Sønderborg, 07.10.2010 Bernhard Wagner Email: [email protected]

Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Page 1: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Technology Platforms for Micro-Nanoelectromechanical Systems

Sønderborg, 07.10.2010

Bernhard Wagner

Email:[email protected]

Page 2: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Fraunhofer Institute for Silicon Technology

Itzehoe site view

Research and productionat one location

Head count:R&D: ~ 150Production: ~ 300

Page 3: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Fraunhofer Society

• Leading non-profit organization for applied research in Europe

• 59 Institutes in Germany

• 15.000+ employees

• Annual research budget ~1.5 B€

• Named after Joseph von Fraunhofer(1787-1826)

Page 4: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Fraunhofer ISIT topics

IC Technology, power electronics

MEMS/ Microsystems

ASIC/MEMS Design

Packaging, assembly, reliability

Biochip systems

Integrated power systems

Page 5: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Facilities and Equipment

Semiconductor technology cleanroom2500 m² - 200 mm wafersFrontend-of-line technologiesVishay: volume production 250.000 w./year

MEMS technology cleanroom500m² clean room - 200 mm wafersBackend-of-line technologies

Research laboratoriesPackaging, testing, reliability, …

Li-Polymer battery laboratoriesR&D and pilot production

Page 6: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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From basic research to volume production

Basic Research Development Production

research partnersU Kiel etc.

new technologies,materials,device principles

component developmentprocess integrationmanufacturability,yield, reliability

wafer fabrication

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Microelectronics vs. MEMS/NEMS Technologies

MicroelectronicsStandardized Technologies, e.g. CMOS Established design tools and libraries

MEMS - NEMSfew standards, large variety on• sensor & actuator principles• functional materials• 3D geometries• various design tools needed:

coupling of electronics, mechanics, optics, fluidics

Page 8: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Technology platformsFirst MEMS law: One product – one process – one package

Problems: high R&D costslong time-to-market

Dedicated MEMS technology development: only for high volume products

Technology Platform Concept

set-up of portfolio of qualified• MEMS process modules• transducer elements with multiple use for different application fields

New device

development:

integration

and adaptation

of platform

modules

Page 9: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Technology platforms

MEMS technology platform = process module + parameterized model

Example: Interdigital comb electrode structureelectrostatic actuation – capacitive sensing

Electromechanical Modellingspring constantsresonant frequenciesdampingcapacitancenon-linearitiescross-couplingstresses…

movable comb(x, y, z + torsion)fixed

comb

Page 10: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Thick polysilicon MEMS technology

Key process steps:

• Deposition of thick (10 - 30 µm) poly-Si• CMP: Chemical Mechanical Polishing• DRIE: Deep Reactice Ion Etching of silicon• Sacrificial layer SiO2 etch in HF-gas

Electrostatic comb drive and sense

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History of thick polysilicon („Epi-Poly“)

Development of thick polysilicon MEMS:EC-EPRIT III – 6416: 1992 -1995 MAXIMA: Multiaxial Monolithic Integrated AccelerometerFraunhofer ISIT, R. Bosch et al.

Driver application: AutomotiveInertial sensors for airbag, ESP, roll-over …

Industrialization by R. Bosch:Accelerometers and gyroscopesCurrent volume: 200 Mio pcs/year

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Device example: Vibrating ring gyroscope

Resonant oscillating ring: fres ~ 10 - 20 kHzComb-drive excitation in-planeComb motion sensing in-planeCoriolis-force induced capactive signal sensing out-of-plane

Signal amplification by Q-factor Need for vacuum packaging

p ~ 0.1 mbar Q ~ 10.000

drive(8x)

motionsense

Page 13: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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MEMS packaging on waferlevel

MEMS need hermetic encapsulationProtection against moisture and dust

Wafer bonding provides robust solution

Application-specific packagingResonant MEMS: vacuum encapsulationOptical MEMS (vis, IR)RF-MEMS

Page 14: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Waferlevel vacuum packaged MEMS resonators

0.01 0.1 11000

10000

100000

Q fa

ctor

pressure (mbar)

cap diced wafer

MEMS resonator quality factor

waferprobe map

Page 15: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Technology platform: Waferlevel packaging

AuSn sealing: bond temp: ~300°CMetallic seal ring (~ 100µm wide)

Thinfilm getter layer on cap wafer Glass frit sealing: bond temp: ~400°C

Page 16: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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3D integration of MEMS with electronics

2D integration 3D integrationfunctional cap with ASIC

MEMS

ASIC

Page 17: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Inertial sensor industrialization

• start of volume production of inertial sensors in Itzehoe1D-, 2D-, 3D-gyroscopes3D-accelerometers

• Applications: automotive, consumer, medical …

• In development:9D sensor unit: navigation and motion tracking:

3D gyroscope+3D accelerometer+3D magnetic field sensor

Page 18: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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MEMS micromirrors

Focus on single mirrors (vis/IR)

Driver application:Mobile laser projection display

Optical sensingOptical 3D imagingOptical writingOptical switching

Mobile TV

Page 19: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Micromirror application in medicine

MEMS scanners for operation microscopesOCT: Optical Coherence Tomography3D near-IR imaging

X- and Y-scanning micromirrors(3 x 4 mm2), integrated in endoscopefor tissue imaging (1995)

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Flying-spot laser projection displays

RGB Laser projection system

MHz-modulated red, green and blue lasers2-axis micromirror Lissajous or raster scanning

high miniaturizationwide color gamutformat-freeno projection lens

Projected image

Page 21: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Scanning micromirror concept and design

WVGA-resolution: 480 lines x 854 pixel, 60 Hzfhor = 14.4 kHz for bidirectional writingoptimum mirror diameter: ~1 mm mirror deflection angle: ± 10° full optical scan angle: 40°

Concept:implementation of poly-Si MEMS platform60 µm thick mirror plate to minimize dynamic deformation,backside etching …

Staggered torsionalelectrostatic comb-drive2 x 30 µm poly-Si

poly-Si

poly-Si

Al

Page 22: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Drive electrodesfast axis, ~ 30 kHz

Sense electrodesslow axis

Drive electrodesslow axis, ~ 1kHz

Sense electrodesfast axis

2-axis scanning micromirror with electrostatic drive and sense

Page 23: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Micromirror waferlevel packaging

Three wafer stack:borosilicate glass cap wafer

deep cavity (~ 0.5 mm)optical quality window + ARC

MEMS mirror wafer

Si bottom wafer with getter

vacuum encapsulation resonant operation (Q ~ 50.000)

low-power drive

Page 24: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Projected Image

dark ambient: A0-formatlight ambient: A4-format

Page 25: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Laserscanning for automotive driver assistance systems

MiniFaros: Low-cost Miniature Laserscanner for Environment Perception:FP7-ICT-248123: 2010-2012

Automotive LIDAR: near IRTOF distance measurementcollision warningpedestrian detection

Challenge: large micromirror: > 5 mmlarge mirror deflection: +/- 15°automotive robustness

Page 26: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Radio-frequency MEMS

membraneanchoring

signal line

dielectric layer

actuation electrodesmembraneanchoring

signal line

dielectric layer

actuation electrodesRF-MEMS switchesfrequency range 0.5 – 100 GHzcapacitive or ohmic contact switchlow loss, power and distortion

Driver application: mobile phonemulti-mode, multi-band, tunable, adaptiveRF front-end (antenna, PA, filter, LNA)4G phone: 10-12 bands 100+ switches

RADAR systemsRF test equipmentWireless communication (satellite, home …)

capacitve switch

Page 27: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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RF-MEMS technology

Minimize RF losses: highly conducting mechanical material:

i.e. metals, not silicon; ISIT: AuNiAuissues: creep, thermal mismatch, thermal stability

substrate: high resistivity silicon (HR-Si) or glass

digital capacitive switch: Con /Coff -ratio ~20electrostatic actuation (~ 50V) reliability issue: charging of dielectric layersISIT: AlN dielectrics

Page 28: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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RF-MEMS waferlevel packaging

Lateral feedthrough Vertical feedthroughThrough silicon vias (TSV)

Metallic seal ring

Page 29: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Technology platform: Through-Silicon-Via technologies

Key process steps:

through wafer via hole etchingvia hole dielectric isolationvia hole metallizationwafer grindingsolder bumping

… + process integration

Thin siliconwafer

Page 30: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Why one more MEMS transducer principle?

Electrostatic MEMS limitations- need for counter electrode- limited deflection range, force- large area consumption for combs- sticking, dielectric charging, pull-in- need for hermetic packaging

Electromagnetic and thermal MEMS- high forces, large deflection- high power consumption- slow

Piezoelectric MEMS- low power - high forces, high speed

Thermal microactuator

Electromagnetic microactuator

Page 31: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Piezoelectric MEMS applications

MicroactuatorsRF-MEMS switchesoptical MEMSmicrofluidics: ink-jet, micropumps, valves

Microsensorsmechanical, magnetoelectric, pyroelectric

Ultrasonic transducers50 - 500 MHz transducer (arrays)

Energy harvestingvibrational harvesting

Tunable RF components

membrane

piezoelectric layer electrodes

nozzle

pump chamber

Page 32: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Piezoelectric thinfilm materials: AlN and PZT

Aluminum nitride, AlNnon-ferroelectric, IC-compatible, low-loss dielectrics,good material for piezoelectric sensors, RF-filterseffective transverse coefficiente31,f

-1.2 C/m2

effective longitudinal coefficientd33,f

5 pm/V

PZT

AlN

Oerlikon Clusterline 200 at ISIT2 µm AlN

Page 33: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Sputtering of PZT (lead zirconate titanate) thin films

Pb(Zrx ,Ti1-x )O3 : ferroelectric, highest piezoelectric coefficients,good material for piezoelectric actuators

Challenges:critical stoichiometry: x

52%

substrate temperature:

550 °C

Two sputter processes:• Gas flow sputtering from metallic targets

high deposition rate:

150 nm/mine31,f

-11 C/m2, d33,f

200 pm/V

• Magnetron sputtering from ceramic targetEC-Project „piezoVolume“, 2010-2012, FP7-NMP-229196

5 µm thick sputtered PZT layer

Page 34: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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PROTEM: Probe-based Terabit Memory FP6-IST-34719

Piezoelectric nanoprobefor data storage- high-speed piezo-actuation- low power piezoelectric readout- fres ~ 250 kHz

Overall project objectives: long-term data storage: > 50ystorage density: ~ Tbit/in2

pit pitch : < 30 nm

Page 35: Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS need . hermetic encapsulation. Protection against moisture and dust. Wafer bonding

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Magnetoelectric composites – biomagnetic interfaces of the future SFB 855

Ultrahigh resolution MEMS/NEMS magnetic sensors for MEG and MKG recording

H. Greve, E. Woltermann, H.-J. Quenzer, B. Wagner, E. Quandt, Giant magnetoelectric coefficients in (Fe90 Co10 )78 B12 Si10 - AlN thin film composites, APL 96, 182501 (2010)

AlNmetglass