Rob van SchaijkMEMS & Micro Devices
06-06-2019
CMUT: a versatile ultrasonic platform developed by Philips
Innovation & Strategy
Strategy, Mergers & Acquisitions, Partnerships
Chief Technology Office organization
Integral part of innovation organization of Philips
External medical & high-tech companies
PersonalHealth
Precision Diagnosis*
Connected Care Design
Image-Guided Therapy*
Sustainability
Idea to Market Excellence
Operations, delivery & services
Technical Expert Group
Innovation Services
*Effective January 1, 2019, the reporting segment Diagnosis & Treatment comprises two clusters: Precision Diagnosis and Image-Guided Therapy.
Product Engineering Organization
Philips
Intellectual Property & Standards
MEMS Foundry
Micro-fabrication
2650 m2 Clean room
ISO13485 certified
Micro-assembly
die/board/system level
2500 m2
ISO13485 certified
Process Development Micro Devices
Smart catheters, in- and on-body devices
Workshop, 300 m2
ISO13485 certified
MEMS & Micro DevicesDevelopment and manufacturing at Philips Innovation Services
High Tech Campus High Tech CampusGreenhouse (Strijp)
Our position in the marketFilling and bridging the gap
Project size [wfrs/yr]
1 100.000
Research flexibility
High (Research Labs)
Low (Foundries)Universities
Institutes
Semi public
Industry
Philips MEMS Foundry
Ecosystem
Filling: many MEMS applications stay below 5 wafers/year Bridging: transfer to larger foundries for much higher volumes
CMUT: Capacitive Micro-machined Ultrasound Transducer
Medical ultrasound application range
Market focus for handheld andwearable applications
Handheld and wearable ultrasoundKeywords: Consumer Ultrasound, High volume, Pregnancy, Bladder, Medical and non-medical applications
Hitachi
Samsung Galaxy
PulsNmore
Philips Lumify
NovioScan Butterfly
Bulk piezo versus MUT
The MEMS US revolution:• High volume production• Eliminate (manual) assembly• Low-cost platform multiple applications• Miniaturization catheters• Higher frequencies• 3D imaging compatible• Enter consumer market
Todays ultrasound imaging:• Based on piezo-ceramics• Difficult to manufacture• No volume production• Labor intensive expensive• Reserved for professional use
Confidential13 Lectures on CMUT: the CM5, April 2019
CMUT fabrication is a batch processTailor made for high volume production
CMUT technology platform
CMUTCapacitive Micromachined Ultrasound Transducer
A replacement for piezo-based ultrasound in the medical domain
CMUT is fabricated by IC technology
Parallel plate capacitor on membrane
Transmits and receives ultrasound at 1 - 50MHz
Collapse mode: the membrane touches the cavity bottom
An RF-voltage makes the membrane vibrate
Advantages:
Robust design, large volume & low cost, high level of integration
Miniaturization & high frequency, lead free for disposable applications
Typically 100 μm
CMUT modular technology platformCMUT offers a lot of design freedom
Wafer
Membrane/
cavity
Bare Si wafer
ASICSubstrate
150mm 200mm
Membrane thickness
Pitch
Gap height
Dielectric
< 1 µm
Variable
< 5 µm
# cMUTs / die
Variable
< 500 µmDiameter
SiO2 SiN
CMUT design
FEM and analytical model
Validated for a wide range of frequencies
Membrane
Electrostatic Force
3 MHz, =280 m
20 MHz, =30 m
9 MHz,= 135 m
Frequency vs diameter
100
Diameter [m]
Freq
uen
cy [
MH
z]
Experimental data
Trend
10
110 100 1000
Membrane
Etch hole(sealed)
Electrodes Vacuum gap
Planarization layer
ASIC
Top view of a CMUT – on - ASIC
x-section
Collapse mode operation
0 5 10 15 20 250
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Frequency (MHz)
Pre
ss
ure
Non-Collapse CollapseBias
Advantages: High performance
Challenges: Stress sensitive Charging driftLifetime issues
Collapse mode: frequency agilityExample: cMUT based Forward Looking Inter Cardiac Echo (FLICE)
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Penetration modeBias low 6MHz
General modeBias nominal 10MHz
Resolution modeBias high 14MHz
• Image from inside the hart (aortic valve)• cMUT frequency tuning 6 14 MHz enables zooming
2x2 mm aperture
3D U/S – Towards general complete solution
• Monolithically integrated CMUT–on-ASIC
• Test array 6x6 mm with 2000 individual elements
• Each element = one membrane
CMUT
Via
Low frequency example: CMUT imaging probe
1 7
-4
0
Frequency [MHz]
-150 VDC
-130 VDC
-120 VDC
50 70RF [V]
Pre
ssu
re a
.u.
2 pulse @ 2.5 MHz
Pressure Spectrum
0 10
-12
-20Pre
ssu
re [
dB
(n
orm
)]20 cmFetal heart:
4 chambers
• fetal imaging, 24 weeks phantom• 20 cm penetration
CMUT CM5
PZT
2 cm
1.2 cm
Confidential22 Lectures on CMUT: the CM5, April 2019Automatic electrical characterization on wafer level
Wafer level electrical characterization• Capacitance• Resonance frequency• Element uniformity• Frequency tunebility & linearity • Model verification (FEM & analytical)
Collapse mode
0 20 40 60 80
Bias voltage (V)
0
10
20
30
40
50
Freq
ue
ncy
[M
Hz]
-10 -5 0 5 10-6
-4
-2
0
2
4
6
Die coordinates
Die
co
ord
inat
es
Wafer map of collapse voltage
Fast CV/impedance measurements
• Fast CV measurements development @ Salland Engineering
• Hardware:
• Fixed probe card for 64 elements
• HV amplifier and capacitance meter
• Based on charge amplifier and lock-in amplifier
25
5
Freq
ue
ncy
[M
Hz]
-150 150DC voltage (V)
sample
hydrophone
Automated acoustic testing:Signal recording for a range of frequencies,
DC voltage, pulse voltages
Test sample characterization: CMUT pressure map
18 20 22 24 26 28
Distance (mm)
-4000
-2000
0
2000
4000
0 2 4 6 8 10 12 14 16
Frequency (MHz)
40
80
Mag
nit
ud
e sp
ectr
um
(d
B)
Inte
nsi
ty
(sam
ple
s)
Transducer level testing
Channel check on Transducer array using Verasonic system
CM5-1
Very large view demonstrator
5 transducers in parallel on flex switch between transducer via DC bias
1 sec programmed delay
Monolithic integrated – Capacitive pressure sensor• Digital: Pressure to Frequency
• 2-wire solutions
• Low drift, Low temperature dependence
• High pressure sensitivity
• Robust: high burst pressure
• 34000 devices on 150mm wafer
Wafer level test @ Salland
• Automatic pressure sensitivity measurement with cantilever probe card (Teradyne ATE)
• Filtering of mal-functioning sensors and delivery of known-good devices in gel-pack
• Multiple site fixed probe card: 10 sites
• Test time per die: ~400ms
• Yield > 90%
Wafer map of pressure sensitivity
Thank you for your attention!
Questions?
Miniaturization challenge: smart catheters
Approximately 10% of the western population will at some moment in their life be treated in a cath lab
Simplifying complex procedures to help you focus on your patients
Our vision:• Seamlessly integrated systems that make image guided therapy simpler, faster and more
cost-effective• Creating a unique, uncluttered, radiation free lab experience • Clinical specialists that become your partner to bring new live image guiding and sensing
innovation to life, enable new therapies
Smart catheters
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Todays Ultrasound transducers:• Obsolete technology• Analog instruments (expensive)• Many expensive (coaxial) wires• Point solutions • Not integrated in the Cath Lab
Next generation smart catheter:• State of the art technology• in-tip AD conversion• Open MEMS technology platforms• MUT with flex-to-rigid (F2R) interconnect• High speed serial interface• Standardized connector (e.g. USB type)• Fully integrated in Cath Lab infrastructure
State-of-art: Volcano Eagle Eye IVUS catheterØ 1.2 mm catheter, 64 piezo elements around circumference
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Transducer region
5 radially placed ASICs
Scanner
• Seamless cMUT-interconnect integration
• Simplifies interventional device manufacturing
• Enables advanced functionality
Flex-to-Rigid (F2R) interconnect platform
Interconnect built into device:
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fully processed silicon substrate
1st polyimide layerinterconnect
island 1 island 2
2nd polyimide layerhard etch mask
island 1 island 2
island 1 island 2
micro flexcable
tab tab
fully processed silicon substrate
Standard Si process flows: Schematic F2R process flow
Technology demonstrator As manufactured in wafer
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Ø 2 mm