Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS...
Transcript of Technology Platforms for Micro-Nanoelectromechanical Systems · MEMS packaging on waferlevel. MEMS...
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Technology Platforms for Micro-Nanoelectromechanical Systems
Sønderborg, 07.10.2010
Bernhard Wagner
Email:[email protected]
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Fraunhofer Institute for Silicon Technology
Itzehoe site view
Research and productionat one location
Head count:R&D: ~ 150Production: ~ 300
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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)
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Fraunhofer ISIT topics
IC Technology, power electronics
MEMS/ Microsystems
ASIC/MEMS Design
Packaging, assembly, reliability
Biochip systems
Integrated power systems
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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
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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
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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
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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
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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
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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
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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
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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
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3D integration of MEMS with electronics
2D integration 3D integrationfunctional cap with ASIC
MEMS
ASIC
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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
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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
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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
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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
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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
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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
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Projected Image
dark ambient: A0-formatlight ambient: A4-format
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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
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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
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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
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RF-MEMS waferlevel packaging
Lateral feedthrough Vertical feedthroughThrough silicon vias (TSV)
Metallic seal ring
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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
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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
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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
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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
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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
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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
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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