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

37

38

Ø 2 mm