mems sensors: from automotive to ce applications -...

1 Engineering | April 2010 | © Bosch Sensortec GmbH 2009. All rights reserved, also regarding any disposal, exploitation, reproduction, editing,

distribution, as well as in the event of applications for industrial property rights.

Bosch Sensortec

MicroNanoTec

Forum “Innovations for Industry”

2010 April 19th Hannover, Germany

Oliver Schatz, CTO Bosch Sensortec

MEMS Sensors:

From Automotive

to

CE Applications

2

Forum "Innovations for Industry"

Engineering | April 2010 | © Bosch Sensortec GmbH 2009. All rights reserved, also regarding any disposal, exploitation, reproduction, editing,


Bosch Sensortec

MEMS Sensors: From Automotive to Consumer Electronic Applications

� Introduction

� Overview technologies

� Function principle and applications of MEMS sensors

� Future trends and applications in Consumer Electronics

� Outlook and summary

3




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MEMS Sensor Market

Source: Yole Dévelopement 2008

RF MEMS

Micromirror/-display

Microphone

Gyroscope

Accelerometer

Inkjet head

Pressure sensor

Microfluidics

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Challenges of MEMS (1/2)� Dedicated processes and equipment

HF vapor etch

Frequency Damping

Sensitivity Capacitance

Frequency Damping

Sensitivity Capacitance

Anodic wafer

bonding

DRIE

� Processes with contamination risks to ICs

� Combined design and control of mechanical and electrical parameters

Source: Semitool Source: Tegal

Source: EVG 1 mm

Anisotropic

etching (KOH)

20 µm20 µm

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Challenges of MEMS (2/2)� Controlling the influence of mechanical stress in the package

� Testing of physical parameters

� Robustness and media compatibility (e.g. for pressure or flow sensors)

air mass sensor pressure sensor

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Market drivers for MEMS sensors

Automotive applications

1. high functional requirements

(high accuracy, self test,

advanced safety concepts)

2. high reliability/quality

(15 years, < 1 ppm, extreme

environmental conditions)

3. low price

(< 3 EUR)

Consumer applications

1. small size

(~ 3 x 3 x 0,9 mm³)

2. ultra-low power consumption

(≤ 200 µA)

3. low price

(< 1 EUR)

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Bosch Sensortec


� Introduction





8

Two fundamental ways doing micromachining

Volume Micromachining

� Building structures through wafer etching

� Structures from mono-crystalline silicon

� Sensor size reduction limited

Surface Micromachining

� Structures generated by applying different layers of

polysilicon

� Good alignment with standardized semiconductor

processes

� Sensor size can be reduced significantly

Surface Micromachining opens up a new world for sensors.




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20 µm20 µm

1 mm

9




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Bosch-team wins German Future Prize

of the Federal President 2008„Smart Sensors for Consumer Electronics, Industrial

and Medical Technologies“

10

Surface micromachining: Bosch-team develops five new

key technologies for series-production.

� Growth of extremely thick layers of polysilicon

� High-precision and fast deep etching - „Bosch process“

� Gas phase etching for release of the structures

� Encapsulation for hermetical sealing

� APSM process – exact vacuum cavities in silicon

Sensors fulfill requirements of consumer electronics

� Sensors considerably smaller and less expensive

� Sensors with less power consumption




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Surface micromachining – the key

Automotive electronics Consumer electronics

11


key technologies for series-production

� Growth of extremely thick layers of polysilicon.





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12

Five Key processes (1/5)


Thickness of structures tailor-made.




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Silicon

Oxide

Epi-Poly

Epi-Poly

Silicon

Oxide

13




� High-precision and fast deep etching („Bosch process“).





Bosch Sensortec

14

Five key processes (2/5)


The base process of surface micromachining worldwide




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DRIE – The “BOSCH process”

� Deep RIE of silicon trenches

� Licensed to many companies worldwide

� “European Inventor of the Year 2007” Andrea Urban and Dr. Franz Lärmer

16 Engineering | April 2010 | © Bosch Sensortec GmbH 2009. All rights reserved, also regarding any disposal, exploitation, reproduction, editing,


DRIE – the BOSCH process


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� Deep RIE of silicon trenches

� Alternating etch- (SF6) and

passivation cycles (C4F8)

� High aspect ratio ( >>10:1 )

� High anisotropy

(underetch <<2 % of etch depth)

� High etch rate

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� Gas phase etching for release of the structures.





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18

Five Key Processes (3/5)





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With this process the structures become movable.

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� Encapsulation for hermetical sealing.





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� Encapsulation for hermetical sealing




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cap

acceleration sensor

Construction of compact elements

21







� APSM process – exact vacuum cavities in silicon.





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22


� APSM process – exact vacuum cavities in silicon

The core of „ASPM process“ is porous silicon




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cavity

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APSM technology advantages

New surface micromachining technique

� Reduced size: bond frames not necessary

� Fabrication of monocrystalline Si membranes

� Full flexibility with size and shape of the membrane

CMOS compatible process

� High synergy between MEMS and ASIC

� No process media that are difficult for a CMOS fab

� Fully integrated process flow in a CMOS wafer fab

� Integrated pressure sensor

24







� APSM process – exact vacuum cavities in silicon.





Bosch Sensortec

25




Bosch Sensortec


� Introduction





26

Movable structures…

� … to measure acceleration and tilt




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Acceleration sensor

27




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MEMS sensors – automotive applications� Airbag Systems

� Acceleration sensors for occupant protection

� Engine Management

� Pressure sensors for engine management

� Vehicle Dynamics Control (VDC)

� Acceleration and angular rate sensors for VDC

� Driver Information

� Angular rate sensor for navigation systems

28


� … to measure angular velocity




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30


� … to measure pressure




Bosch Sensortec

membrane

31

Automobile applications

e.g. Motor management

� Highest accuracy over temperature and lifetime

� Integrated, single chip solution

� stable single-crystalline membrane

� Diagnosis capability

� Small SMD package




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new

(APSM)

old

(KOH)

Consumer electronics applications

e.g. Altitude measurement

� High absolute accuracy

� Extremely high precision

� Very small, robust LCC8 ceramic package

� Ultra-low current consumption

� Digital I2C interface

Pressure sensors for automotive and CE applications

32




Bosch Sensortec


� Introduction





33

…the key for versatile new applications

� Sensors considerably smaller

� Sensors with much less power consumption

� Sensors less expensive

� Sensors fulfil the requirements of

consumer electronics

Surface Micromachining…




Bosch Sensortec

34




Bosch Sensortec

Evolution of requirements (1/2)

Packages of acceleration sensors

PLCC28

(Automotive)

1996

SOIC16w

(Automotive)

2002

4x4 LGA

(CE)

2006

SOIC14n

(Automotive)

2006

3x3 QFN

(CE)

2007

2x2 LGA

(CE)

2010

35




Bosch Sensortec

Evolution of requirements (2/2)

Packages acceleration sensors

0

20

40

60

80

100

120

140

1995 2000 2005 2010

Pa

cka

ge

fo

otp

rin

t (m

m²)

Automotive

CE

36




Bosch Sensortec

MEMS sensors – the senses for mobile devices

� Mobile phones, PDAs

� Intuitive menu input through

motion and position change

� Gaming and toys

� New gaming experience through motion interaction

� Mobile computing

� Data protection by free-fall detection

� Sports and fitness

� Monitoring through step-counting and altimetry

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Bosch Sensortec

Use cases for MEMS sensors in mobile phones

User Interface

• Tap control

• Gaming input

• Menu navigation

Position Detection

• Upside down

• Portrait / landscape

Pedestrian navigation

• Speed & distance estimation

• Altitude detection

• Location based services

Motion Detection

• Step counting

• Activity monitoring

• Power management

38




Bosch Sensortec


� Introduction





39




Bosch Sensortec

Bosch – leading the market in MEMS sensors

0

50

100

150

200

250

300

350

400

450

500

RO

BER

T BO

SC

H

STM

ICR

OELE

CTR

ON

ICS

FRE

ESC

ALE

DEN

SO

AN

ALO

G D

EVIC

ES

INFIN

EON

(inc

l.Sen

sono

r)S

ENS

ATAP

ANA

SON

IC

SC

HN

EID

ER

ELE

CTR

IC

KN

OW

LES

AC

OU

STICS

Sa

les

(M

$)

Source: iSupply estimation, 2008

revenues for TOP50 MEMS

suppliers, shown here: TOP10

MEMS sensor suppliers

Fo

un

dry

40




Bosch Sensortec

1 billion MEMS sensors produced*

0

500

1000

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Ac

cu

mu

late

d p

rod

uc

tio

n v

olu

me

(m

io.)

*Bosch total MEMS production (automotive and consumer)

41




Bosch Sensortec

Future of MEMS

� New applications are arising

MEMS autofocus

Micromirror for microprojection systems

Source: Microvision

Source: SiimpelSource: IMEC

Energy Harvester

Source: STM, CEA

Micro Fuel Cell

42




Bosch Sensortec

Summary

Automotive

� MEMS is main driver for sensor development

� Permanent enhancements of MEMS technology enables

miniaturization of components and new functions

� Continuous development of new device generations

Consumer electronics

� MEMS is enabling technology for new functions in CE

� Key factors: size, power consumption, price

� In future large variety of new applications in many areas

43




Bosch Sensortec

Thank you for your attention!

mems sensors: from automotive to ce applications -...

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