Jean-Philippe POLIZZI

MEMS Business Development Manager, DCOS, CEA-LETI

AN OVERVIEW OF SOI BASED MEMS

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About Leti

Founded in 1967

1,900 researchers

54 start-ups

& 365 industrial partners

2700 patents

318 M€ budget (80% contract R&D)

CEO

E SABONNADIERE

250 PhD students + 40 post PhD

with 85 foreign students (35%)

~ 40M€ CapEx

311 generated in 2016

40% under license

8500 m² clean rooms200 and 300 mm wafer fab

Operated 24/7

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WHAT ARE MEMS AND NEMS ?

•MEMS is the acronym of Micro Electro-Mechanical Systems

•MEMS are mechanical systems with components in the micrometer scale

•MEMS are micron sized devices that perform mechanical, optical, chemical

or fluidic functions . They are generally realized by the technology used to

manufacture integrated circuits, that is thin film deposition, photo-

lithography and etching.

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10’s

00’s

90’s

MEMS MARKETS EVOLUTION

80’s

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WHAT ARE THE USED FOR ?

$0M

$5 000M

$10 000M

$15 000M

$20 000M

$25 000M

2014

2015

2016

20172018

20192020

MEMS devices US$M forecasts per application market

Aeronautics Automotive Consumer Defense Industrial Medical Telecom

Source: Yole Développement

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Thin Film Technology

(Vac.dep. / shadow mask)

80 90 00

year

10 20

Tran

sfe

rsK

ey d

ate

s

Bulk Technology

(Litho / wet etching)

1984 - Comb drive accelero patent

19

81

Hygrometer

Weight sensor

19

80

Pacemaker accelerometer

Geophone

19

96

Miniature pressure sensor

19

96

Accelerometer

20

05

Quartz accelerometer

19

87

High perf. pressure sensor

19

98

Surface Technology

(Litho / DRIE on SOI)

1996 - Startup creation

30+ YEARS BACKGROUND IN MEMS SENSORS

Inertial platform

2011M&NEMS platform

2014

Above-IC GMR Technology

2012

XXXXXX

PZT actuator process

2017

Capacitance stacking

2016

XXXXXX

Nano-scale Technology(DUV litho on thin SOI)

2007 - Caltech Alliance

2013 - Startup

2014 Startup

2011 - Startup

2015 Startups

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TECHNOLOGICAL PLATFORM• MEMS 8”(1000 m²) + FE 8”(3000 m²) Cleanrooms

• Specific MEMS equip. : DRIE, HF-vapor, bonder…

• 5 shifts working: 7days/week – 24h/days

LCMC Lab.

Sensors Components

LCRF Lab.

RF Components

LCMA Lab.

Actuators Components

LCFC Lab.

Characterization & Reliability

3D Lab.

Packaging &Interposer

Overall MEMS activities > 200 people

Microsystems section

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WHY USE SOI FOR MEMS ?

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HOW MEMS ARE MADE ?

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THE EFFECT OF STRESS GRADIENT

#1 Reason for using SOI: (almost) Stress Free Material !

#1 Reason for using SOI: Compatibility with thick

structural layers

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Silicon is an excellent

mechanical material !

E=169 GPa

WHY USE SOI FOR MEMS ?

#2 Reason for using SOI: Single Crystal Silicon is an

excellent structural material

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WHY USE SOI FOR MEMS ?

#3 Reason for using SOI: No CTE mismatch with

underlying support

Buckling

happens

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WHY USE SOI FOR MEMS ?

#4 Reason for using SOI: Built-in sacrificial layer

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WHY USE SOI FOR MEMS ?

#5 Reason for using SOI: Precise thickness control of

structural layer

Pressure sensors MUTs Force sensors

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WHAT TYPES OF MEMS ?

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Accelerometer

Inertial Sensors

Geophone

3D Gyro

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Example of technology transfer to industrial company

HARMEMS accelerometer shipments - units

Development and transfer of the HARMEMS technology to Freescale

HARMEMS accelerometer shipments: 350+ million units

Inertial Sensors

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Pressure

Membrane based Sensors

3D Force sensor

cMUT and

pMUT

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NEMS

200 nm AlSilinewidth200 nm AlSilinewidth

L= 1.6µm - ø~10nm

MEMS for time reference

(nano-gaps)

100 MHz / Q=40 000

NEMS RESONATORS CO-INTEGRATED WITH CMOS

Monolithic integration with

CMOS

SEM view

CMOS

NEMS

Capacitive resonators with

STMicro 0.35µm CMOS (IEDM

2012)

Piezoresistive resonators with

LETI FDSOI CMOS (ISSCC 2012)

MOS circuit

NEMS

Si(encapsulated

with SiO2)

Oxide

700nm

Amplification

Bias stageBuffer stage

Piezoresistive

gauges used

for detection

Electrode for

capacitive

in-plane

actuation

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NEMS-BASED SENSORS PLATFORM

FOR GAS AND BIO-SENSING

Mass

loading

Mass

loading40

2

lM

f

m

f

eff

Responsivity

3

0

2 lMm

Resolution

µbolometer

Freq

uen

cy s

tab

ility

Freq

uen

cy s

tab

ility

Cellular force sensor

Gas detection Mass-spec for Bio applications

• High resolution• Very short response time• High integration

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MEMS size inertial mass

+Nano-size piezoresistive gauge

Miniaturized sensors

Generic platform

Not sensitive to parasitics

Well known and robustpiezoresisitive detection

Strongly differentiated approach (20+ patents)

3-axis

Gyroscope

3-axis

Magneto

3-axis

Accelero

X

ZY

Microphone

M&NEMS "Generic" Platform

Pressure

sensor

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M&NEMS 6-AXIS COMPASS/ACCELEROMETER

6-axis mechanical footprint ≈ 1,1mm²

Low power consumption (30µW/axis in DC)

Robust to external field (x10 compare to Hall, GMR, TMR)

1 electronic common for each of the 6 axis

High linearity

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3-AXES M&NEMS GYROSCOPE

Mechanical footprint ≈ 2 mm²

Cross-axis rejection > 59 dB

ARW 1,8 mdps/√Hz

Bias Instability = 1.2°/hr

Linearity error is < 0.25% of the FSR

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M&NEMS PRESSURE SENSOR

Mechanical footprint ≈ 0.1mm²

High linearity

Auto-test electrode

Reliability:

Protected gauge from external environment

Over-pressure protection (stops)

Compatible with high temperature

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CONCLUSION

80% of the MEMS sensors developed in

Leti are based on SOI wafers Accelerometers, gyrometers, pressure, force sensors

Microphones, MUTs

Mass sensors based on vibrating beams

1. Stress free structural layer

2. Single Crystal Silicon shows superior

mechanical properties

3. No CTE mismatch with support

4. Built-in sacrificial layer

5. Precise control of structural layer thickness

30 years experience in MEMS

200 people involved in MEMS (sensor, actuator, RF, packaging, process, characterization)

All 8” MEMS/NEMS technologies in-house

Leti, technology research institute

Commissariat à l’énergie atomique et aux énergies alternatives

Minatec Campus | 17 rue des Martyrs | 38054 Grenoble Cedex | France

www.leti.fr

Thank you for your attention