© 2005
Silicon Microphone Industrial and market focus
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Content (of the global report)• 6. Silicon Microphone Technology Overview
(p.74)• Microphone definition• Advantages of Silicon Microphones vs. ECM• Silicon MEMS Technology• Detection principle description
• 7. Silicon Microphones Manufacturing Challenges (p.91)
• Design• Processes• Cost analysis on several device types• Opportunity to decrease price• Development costs per players
• 8. Appendix
• 8.1 General overview of the MEMS Business (p.99)
• MEMS History & Genealogy• MEMS market challenges
• 8.2 MEMS Manufacturing Overview (p.115)• Key Differences between MEMS and IC Lines• MEMS typical flow chart• Micromachining technologies• Why integrated MEMS: from MEMS to
Microsystems• MEMS processes challenges
• 1. Executive Summary (p.3)
• 2. Methodology (p.4)
• 3. Market Opportunity (p.9)• ECM markets Key points• Market opportunity for MEMS microphones• Description of applications• Market evaluation per application• Market trends
• 4. Industry Status of Development (p.31)• Product introduction schedule• Silicon Microphone Player Profiles• Current partnerships
• 5. Industry Organization and Trends (p.62)• Business model comparison• Evolution of the ECM competition• From Analog to Digital evolution• Technology winners: monolithic vs. several chip
solution?• Key drivers of microphone manufacturer and
handset manufacturers relationship • From microphone device to microphone module• M&A
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3. Silicon Microphone Market Opportunity
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3. Silicon Microphone Market Opportunity Market Descriptions
• Silicon Microphone potential applications are identified on the schematic above
• Market penetration is estimated to be in the following order:1. Consumer2. Medical3. Automotive4. Industrial
SILICON MICROPHONE
CONSUMER
INDUSTRIAL
AUTOMOTIVE
MEDICAL Active noise cancellation
Hearing aids
PDAs
LaptopsMobile phones
Acoutics crash sensors
Active noise cancellation
Hand free sets
PCs
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3. Silicon Microphone Market Opportunity Market Estimation
• The total available market has a great potential.– 2008 global penetration rate is only 16%
SiMicro Total Market
0
500
1000
1500
2000
2500
3000
2004 2005 2006 2007 2008
Mun
its
0
50
100
150
200
250 M$
TAM (Munits)SiMicro volume (Munits)SiMicro market value (M$)
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4. Industry status of development
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4. Industry status of development Players detection principle
• Three types of silicon microphones have been identified so far:– Capacitive detection is of high growth and interest today
• Dedicated to low cost and moderate performances devices: i.e. the replacement market of the ECM– Microflow detection is related to fine sound measurements
• Oriented toward measurement market– Optical detection is more military /security oriented
• This detection is very accurate and allow lot of noise reduction• It main feature is to be undetectable compared to other technologies• They are mainly developed for military applications
Detection principlesDetection principles
CapacitiveCapacitive PiezoelectricPiezoelectricPiezoresistivePiezoresistiveOpticalOptical MicroflowMicroflowKnowles AcousticsSonionMEMSMEMSTechInfineonAkusticaMatsushitaApogeeHosidenVTT Electronics…
Phone-OrToshibaNASA
Microflown
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4. Industry status of development Existing products
• 4 Companies are in production today:
• Knowles Acoustics (US):- In production since 2003- 2004 sales: 50 M units- Silicon microphone chip on PCB
with metallic lid
• SonionMems (DK):- Part of the Sonion Group (3000
persons, 114 MEuro sales in 2004)- Technology leader with volume
manufacturing capabilities- They are shipping sample in 08/2008
and volume is expected very soon- We expect product commercial release
in September-October 2005
- Phone-Or (IL)- Specific optical microphones
dedicated to security applications
- Microflown (NL)- Specific microphones for
measurements
• Many other are still at development stage
– Hosiden (Korea)– Akustica (US)– Apogee (US)– Infineon (D), – Best Sound
Electronics (KR) NHK STRL (JP)
– Innovation Technology Co. (CN)
– Merry ElectronecsCo,Ltd (Taiwan)
– JL World (JP)
SonionMEMS SiMic product for mobile applications
Knowles Acoustics SiSonic product with opened mettalic lead
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1995
4. Industry status of development Product introduction schedule
2001 2004 20102007
Star
t of r
e sea
r ch
eff o
rts
1998
Fir s
t co
mm
erci
aliz
a tio
n 2003 - Knowles Acoustics2005 – SonionMEMS for
mobile phones
1997 - Infineon
2006 – MemsTech
2001 - Akustica
2003 - Apogee
1992
2007 – SonionMEMS for hearing aids applications
2006 – Akustica
1995 -SonionMEMS2002 - MemsTech
1992 -Knowles
2006 – Apogee
1994 - NCT
<1992 – Draper Lab
2006 – Infineon
2006 – … (confidential newcomer)
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4. Industry status of development Current partnerships
Markets Partners Prod.GN ReSound (DK) 2006
BSE (Best Sound Electronics) (KR) Cell-Phone Samsung (KR) R&D in 2005 Capacitive
Prod since 2003
Innovative Technology (INN Acoustics) (CN) Cell Phone D in 2005 Capacitive
Microflown (NL) Measurement Microphone Prod Microflow
NHK (JP) Broadcast Panasonic Mobile Communication (JP) R&D in 2005 Capacitive
Toshiba Corporate R & D Center Auto Handset R&D in 2005 Optical
Prod in 10/05
No prod.
Neonode (SW)MEMSCAP (FR)
Siemens (D)Siemens Hearing (D)
Motorola’s TCG (USA)Kenwood (JP)
SonionKirk (DK)
Nokia (FI)
Techno
Infineon (D) Auto Handset, Hearing aid Capacitive?
VTT Information Technology (FI) Cell-Phone Capacitive
Akustica (USA) Cell-Phone, Hearing aid Capacitive
Knowles Acoustics (USA) Cell-Phone Capacitive
Phone-Or (IL) Auto Handset Optical
SonionMEMS (DK) Cell-Phone, Hearing aid Capacitive
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5. Industry organization and trends
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3. Silicon Microphone flow chart :from design to OEM integration
STEP STRUCTURE DESIGN
PROCESS DESIGN
DIE MANUFACTURING ASSEMBLY PACKAGING
and TESTS OEM ASSEMBLY
Resources required
MEMS and ASIC design expertise Electronic assembly line
OEM
Silicon Microphone
Final products: Mobile Phone, Hearing aids….
Players Design department Foundry Back End
Chip Wafer Dies
Acoustics expertise: design and electronics
Process knowledge and Manufacturing capability
Back-End and Test capability
Silicon microphone flow chart model
Chips assembly
MEMS Manufacturing processes definition and tests
Handling and soldering on PCB
Sensing element structure design
MEMS Foundry
ASIC design
ASIC manufacturing processes definition and tests
ASIC Foundry
Packaging
Tests Ship
ping
FIN
AL
PRO
DU
CT
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3. Silicon Microphone flow chart :Business model comparison
• To that extend, three technological models ave been identified:
– SonionMEMS products are made from 3 silicon dies assembled together
• Each die comes from an different foundries (partners)• Dies are assembled at SonionMEMS site (proprietary
assembly process)
– Knowles Acoustics SiMicro:• ASIC and MEMS microphone comes from different foundries
(partners)• Dies are glued onto a PCB substrate. • Dies are connected to metallic PCB contacts using wire
bonding• Frame and metallic lid are fixed onto the PCB and the
connected dies
– MemsTech• ASIC and MEMS sensing element manufactured within
MemsTech• It is a hybrid microphone which is 1.4mm*4mm (die size is not
available) – The product size need to be checked when datasheets would be
available
ASIC chip
Substrate chipMicrophone chip
bond wire
microphonechip
lid with acoustical opening
backplate
contactcontact
glob top
PCB
adhesive
fram
e
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5. Industry organization and trendsBusiness model analysis
• Knowles Acoustics was first in the market thanks to– Its basic technology
• Two chip component• Basic packaging metallic lead
– Its highly flexible business model• Fabless company• Two manucfacturing sources: Sony, Memscap
• Fabless business model is a general trend among MEMS microphone manufacturers– Subcontracted to MEMS foundries: Knowles, SonionMEMS– Subcontract to standard CMOS foundries:
• For ASIC: Knowles, SonionMEMS• For the whole device: Akustica, Apogee
• Integrated fabrication is reserved to big companies with SC fab– Infienon, Matsushita
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6. Silicon Microphone technology overview
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6. Silicon Microphone technology overviewMicrophone definition
• Definition:– A microphone is a device that converts sound
into an electrical signal
– In all microphones, sound waves (sound pressure) are translated into mechanical vibrations in a thin, flexible diaphragm. These sound vibrations are then converted into an electrical signal.
– Today the main microphone technology used is the ECM: Electret Condenser Microphone.
• In a condenser microphone, the diaphragm acts as one plate of a capacitor, and the distance changing vibrations produce changes in a voltage maintained across the capacitor plates
• An electret is a dielectric material that has been permanently electrically charged or polarised.
Microphones are basically a high speed pressure sensor
One of the smallest ECM from SMK Corporation (6 mm in diameter and 1.5 mm)
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6. Silicon Microphone technology overviewAdvantages of Silicon Microphones vs. ECM
• Design advantages– Size reduction ideal for space-constrained designs
• Back plate and diaphragm in a MEMS microphone are approximately 10x smaller than those in the smallest ECM
• allows a packaged MEMS microphone to start at approximately the same size as the smallest ECM
• Potential to shrink much further as MEMS microphone technology matures
• Consumes less PCB space• Requires smaller height allowances
– Easy to integrate with new functions • Thus increasing the adaptability of the microphone for
different applications• First functions integrated is amplification of the acoustic
output• For example, several MEMS microphones include output
amplifiers capable of 20 dB gain in the signal transmitted to the codec
– The stronger output signal is less susceptible to noise. – Suitable when the acoustic input comes from a distance and is
weaker: » products such as camcorders and video phones for example
• This both simplifies design and saves board space.
Figure 2: Comparison of 4mm ECM vs. MEMS diaphragm
Figure 3: Size comparison of 4mm ECM vs. MEMS microphone
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6. Silicon Microphone technology overviewSilicon MEMS Technology
• The silicon MEMS microphone is composed of the same parts than the ECM:– A membrane (few µm Silicon material thickness) which act as the flexible diaphragm– A back plate with is the reference of the capacitive sensing and is parallel to the membrane– Back plate let air from the 10µm cavity flow through its holes.
• It senses sound upon 5 main detection principle:– The vibration sound bend the membrane.– Membrane variation is detected using one of the 5 techniques:
• Capcitive• Piezo resistive• Piezo electric• Optical• Microflown
– The measured variation is then amplified and translated into electrical signal corresponding to the sound vibrations
Exmaple of NHK Capacitive Silicon Microphone
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6. Silicon Microphone technology overviewDetection principle
• Three types of silicon microphones have been identified so far:– Capacitive detection is of high growth and interest today
• Dedicated to low cost and moderate performances devices: i.e. the replacement market of the ECM– Microflow detection is related to fine sound measurements
• Oriented toward measurement market– Optical detection is more military /security oriented
• This detection is very accurate and allow lot of noise reduction• It main feature is to be undetectable compared to other technologies• They are mainly developed for military applications
• This technology analysis will only cover the capacitive silicon microphones– 90 of developments and production are using capacitive detection principle
Detection principlesDetection principles
CapacitiveCapacitive PiezoelectricPiezoelectricPiezoresistivePiezoresistiveOpticalOptical MicroflowMicroflow
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7. Silicon Microphones Manufacturing Challenges
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7. Silicon Microphones Manufacturing Challenges Challenges in Manufacturing Processes
• General concepts in MEMS Manufacturing:
• Reduce number of process steps is the main goal in MEMS design– Cost of MEMS die is generally estimated using cost in $/step/mm²– Great cost advantage which is a key success factor
• MemsTech seems to have achieved an only 3 process step design• Matsushita has announced a 2 process steps
– Decreasing number of steps reduce the manufacturing complexity• Yield is expected to be higher
• Avoid costly processing technologies such as:– Dry etching– Wafer bonding– Sacrificial etching (because of its well-known risk of stiction)
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7. Silicon Microphones Manufacturing Challenges Challenges in Technology Design
• The active region of the MEMS device is the gap between membrane (or diaphragm) and back plate
• The membrane has to – Measure the low pressure level (e.g. a sound pressure level of 100
dB -which corresponds to a pneumatic hammer- is equivalent to a pressure of 2 Pa).
– High dynamic measurement range from several Hz up to at least 10 kHz
– The two requirements mean that very thin diaphragms must be used(ex: NHK prototypes changes from 5µm thickness to 4µm)
• The gap must be – Of uniform thickness – As thin as possible to be more sensitive (i.e. NHK prototype
deceased their gap from 15µm to 10µm)
• Structure design has to be thought using has few as possible process steps:
– MEMS average process steps for a structure is 11– Die cost is directly link to number of steps– One process step correspond to a lithography step
• This is one of the most expensive manufacturing part:– Lithography equipments are costly – Lithography is usually the bottleneck of the fab in through put– Masks (pattern which are transferred onto the wafer) are expensive– One step = One mask
– For example MemsTech claims it managed to have a 4 step only process for its microphones
Membrane / Diaphragm
Air gap
NHK silicon microphone structure