1

Integrated MEMS by adhesive bonding

M.Esashi and S.Tanaka

Tohoku University

1. Introduction

2. Wafer bonding first approach

3. Wafer bonding last approach

4. Open collaboration for MEMS on LSI

5. Conclusions

12. July, 2012

21990 2000 2010 year

Pressure sensor

Accelerometer & Gyro

Communication

Image

(MEMS array)

Engine controlBlood pressure sensing

Accelerometer for airbag

Tire pressure monitoring

Gyro for cameraAccelerometer for user interface

MEMS switch

Print head Display (DMD)

IR imager (Night vision)

Trends of MEMS (Micro Electro Mechanical Systems) products

Oscillator

Microphone

Structure + sensor + circuit + actuator

Advantages

・Miniaturization(high sensitivity, low power, good spatial resolution, etc.)

・Integration(low cost, array etc.)

3

Inertia sensors (SIP) MEMS chip + LSI chip

Array MEMS for display

(SOC) MEMS on LSI

(Toyota)(ST microelectronics)

(Invensense)

MEMS for wireless communication

(Adhesive bonding of MEMS wafer on LSI wafer)

4

1. Introduction

2. Multi Band Wireless Communication Systems

Multiband filter on LSI

PZT switch on LSI

SAW filter on LSI

3. Sensors for Safety

4. Open Collaboration

28. May, 2012

5

CMOS compatible AlN Lamb wave resonator

Ge

Al

Au/Cr

AlN

1. Ge patterning and SiO2 deposition

2. Metal patterning and AlN deposition

3. AlN and Au/Cr patterning

4. Ge sacrificial etching

SiO2

Mo

LSI

(K.Hirano (Japan Denpa Ltd,) 2nd Internl. Workshop on Piezo-devices Based on Latest MEMS Tech.(2008) 111)

Filters and oscillators for multi-band RF systems

(Polytec high frequency laser doppler imaging)

LSI

Deposition-based approach (Surface micromachining)

(300℃)

6Wafer-level Hetero-Integration Approaches

AlN Lamb wave resonator

Micro mechanical filters on LSI

SAW filter on LSI

(Damage-free MEMS fabrication on LSI)(High-density, small stray capacitance and inductance)

(Electrical interconnection using metal bonding) (Flexibility in fabrication)

7Application of adhesive bonding

Tactile sensorBonding with BCB (Cyclotene)

Micromechanical resonatorBonding with polyimidePartly etching of polymer after bonding

SAW filter on LSIBonding with UV curable resinRemove after temporary bonding

Surface micromachining

Sacrificial layer

Adhesive bonding process

8(H.Yanagida, IEEE MEMS2011, 324)

Removal of polymers by ozone in acetic acid

9AlN/Si composite disk resonators and FBAR for multiband wireless sultiband wireless systemsystems(T.Matsumura (NICT), J. of Micromech. Microeng., 20, 9 (2010) 95027)

Disk resonator

High freq. laser dopplerimaging (293 MHz) (Polytec UHF120)

10

FBAR (Film Balk Acoustic Resonator)(T.Matsumura, M.Esashi, H.Harada and S.Tanaka, 2009 IEEE Internl. Ultrasonic Symposium (2009) 2141)

11PZT MEMS Switch on Integrated Circuit

A

C

A B

GND RF I/O GND

Contact

Bias electrode

LSIAl pad

C

BAuPZT

Cu SiO2

Pt

(Matsuo, Moriyama, Esashi, Tanaka (Tohoku Univ.), IEEE MEMS 2012, 1153-1156)

PZTPt

Au

10MΩ

Deflection

0

2

4

6

8

10

12

14

0 2 4 6 8 10

Def

lect

ion

[µm

]Voltage [V]

Initial gap

Initial gap

12

PZT MEMS Switch on Integrated Circuit

Si wafer

IC wafer

PZTPolymer Metal

(Matsuo, Moriyama, Esashi, Tanaka (Tohoku Univ.), IEEE MEMS 2012, 1153-1156)

13

CMOS switch control circuit

INV INVINVINV

Delay Circuit

CLKVDD

GND

SOUT_1(Output “00”)

SOUT_2(Output “10”)

SOUT_3(Output “01”)

SOUT_4(Output “11”)

Delay Circuit

INV

INV

INV

Decorder DFF INV

INVDFF

DFF

DFF

INV

INV

INV

IN_1IN_2

0.0

4.0

8.0

12.0

16.0

20.0

24.0

0 2000 4000 6000 8000 10000

Volta

ge [V

]

Time [µs]

IN_1IN_2DOUT_1DOUT_2DOUT_3DOUT_4

VDD : power supply, 3.3VCLK : clock signal,3.3 V, 5 MHzIN_1, IN_2 : switching signal, 3.3 VDOUT_1~4 : D flip-flop’s output

14

PZT sol-gel deposition process

Automated machine

PbO,TiO2

(Sol-gel : Mitsubishi Materials, ZrO2:TiO2:PbO = 52:48:110 in mol.)

15

Dispensing and coating

Drying (200℃) and pyrolysis (300℃)

Crystallization (680℃ RTA)

3 times

PZT sol-gel deposition process

16

SAW devices on LSI

(Kyeong-Dong Park, M.Esashi, S.Tanaka, IEEJ The 26th Sensor Symposium, 37 (2009)

SAW device

LSI

Frequency spectrum obtained from SAW oscillator on LSI (502 MHz)

Wafer bonding last approach

17

1. Introduction2. Multi Band Wireless Communication Systems3. Sensors for Safety

Accelerometer and gyroRange imager using optical scannerTactile sensor network

4. Wafer Level Packaging 5. Open Collaboration

28. May, 2012

18

Rotational gyroscope levitated electrostatically using high speed digital signal control

MESAG-100 (Micro Electrostatically Suspended Accelerometer Gyro)

(Simultaneous measurement of 2 axes rotation and 3 axes acceleration)

(T.Murakoshi et.al. : Jpn. J. Appli. Phys., 42, Part1 No.4B (2003) p.2468)

Rotor diameter1.5mm 74,000rpm

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Ranging imager for safety systems and other applications

(T.Ishikawa,H.Inomata : Japan Signal Technical Report, 33, 1 (2009) 41)

Color correspond to the distance

２D Optical scanner(N.Asada et.al., IEEE Trans. on Magnetics, 30 (1994) 4647)

Ebisu station (platform doors using the ranging imager)

20

(S.Kobayashi & M.Esashi, Technical Digest of the 9th Sensor Symposium,(1990),137)Common 2 wires tactile sensor array (polling type)

(1,000 Tr./chip in our lab., 1,000,000 Tr./chip in company)

2121Tactile sensor network for robot (event driven type)

(M.Makihata, M.Muroyama, 26th Sensor Symposium (Oct. 15-16, 2009))

Safe nursing robot

22Network voltage

23Fabrication process of tactile sensor

24

1. Introduction

2. Multi Band Wireless Communication Systems

3. Sensors for Safety

4. Open Collaboration

Shared wafer

Hands-on access fab.

Partnership

28. May, 2012

25

MEMS process facility for 20 mm waferMany process equipments have been made in house.Simple and basic equipments are suitable for training people who have experiences of all the process and for developing new devices taking advantages of process flexibility.The facility has been shared by many laboratories.More than 100 companies dispatched researchers (full time, 2years).

Unique facility like toy for MEMS prototyping

26

Ricoh, Toyota motor, Pioneer, Nippon signal, Toppan TDC,Kitagawa iron works, Sumitomo precision, NIDEC COPAL elec. Nikko, Toyota central R&D lab, Nippon dempa kogyo, Japan aviation elect. Ind., MEMS core, MEMSAS, Furukawa Electric, DensoLaboratories in Tohoku Univ.

Shared CMOS LSI wafer

27

→ 「Shared wafer」 for additive MEMS processes to reduce the development cost

Innovation center for fusion of advanced technologies 2007~2016FY

http://www.rdceim.tohoku.ac.jp/

→ 「Hetero Integration」 to integrated heterogeneouscomponents for value added devices.

→ 「Massive parallel EB exposure systems」 to produce small volume LSI cost effectively.

→ 「Shared facility for industry」 to enable the MEMS Hands-on access fab. for prototyping without facilities.

World-leading innovative R&D center 2010 ~ 2013FYhttp://www8.cao.go.jp/cstp/sentan/index.html

Solutions to the economical crisis of advanced LSI

28

Concept of the massive parallel EB exposure system(2D array of micro columns which have active matrix nc-Si electron emitter array)

Nanocrystalline silicon

29(N.Ikegami et.al., Active-Matrix nc-Si Electron Emitter Array for Massively Parallel Direct-Write Electron-Beam System, SPIE 2012 Advanced Lithography (2012/2/12-16) San Jose, USA)

Nc (Nanocrystalline)-Si emitter array fabricated on SOI substrate

(A Kojima, H. Ohyi and N. Koshida, J. Vac. Sci. Technol., B26 (2008) 2064)

Cascaded tunnel junction for ballistic electron emission

30100 x 100 active-matrix driving LSI

100×100

31

Electron BeamElectron Beam

Confirmation of electron emission from NC-Si electron emitter driven by CMOS LSI

NC-Si electron emitter

CMOS LSI

32

Electron emitter array

Lens Lens

V acceleration > V acceleration

Electronic aberration compensation

Aberration

33

Al

In Au Cr

LSI

Glass (or Si)

LSI

Glass (or Si)

1) Alignment of electron source to LSI

2) Au-In-Au TLP bonding (200℃~)

LSI

3) Ge etching (H2O2)

The fabrication process of active matrix electron source using adhesive bonding

LSI

4) Polymer removal

Ge

Polyimide

Pierce gun for condensing and collimation of electron beam

34

Shared facility for industry to prototype MEMS devices (4 / 6 inch)Hands-on access fab. (Nishizawa memorial research center in Tohoku Univ.)

Contact person : Assoc. Prof. Kentaro Totsu totsu@mems.mech.tohoku.ac.jp

Companies which cannot prepare their own facility dispatch their employees to operate equipments by themselves.

35Shared facility for industry to prototype MEMS devices (4 / 6 inch) Hands-on access fab.

36Sendai MEMS showroom (2012/5/16 renewal opening)

Efficient way to access accumulated knowledge is important for heterogeneous integration

37

Tohoku Univ. Micro System Integration Center・MEMS prototyping facility (20mm □)

・Micro/Nanomachining research and education Center (MNC) (2 inch LSI)

・Hands on access fab. (4/6 inch)

MEMS Park Consortium (MEMSPC)

MEMS Core (4/6 inch line)

Advantest components et.al.

Germany FhG

MEMS Industry Group in USA

Belgium IMEC

Industrial Tech. Inst. Miyagi Pref.

MEMS PC member companies (80)

Local companies

Annex Esashi lab.

Sendai city

Sendai stealth dicing lab.

MEMS show room

Tsukuba Innovation Arena (TIA)

AIST Research Center for Ubiquitous MEMS and Micro (UMEMSME) (8 inch)

Nissan motors, Dainippon Printing et.al. France LETI

Murata MFG

NICT

Crestec

Chiba Univ.

Funding program for world-leading Innovative R&D on Science and Technology (FIRST)(2010-2013) ~5MUS$ / Year

Tokyo Univ. of Agriculture and Tech.

Ricoh, Toyota motor, Pioneer, Nippon signal, Toppan technical design center, Kitagawa ironworks, Sumitomo precision, NIDEC COPAL electronics, Nikko, Toyota central R&D labs, Nippon dempa kogyo, Japan aviation electronics industry, MEMS core, MEMSAS, Furukawa Electric, Denso

R&D Center of Excellence forIntegrated Microsystems(2007-2016) ~5MUS$ / Year

Hamamatsu Photonics. et.al.

Italy Poly Tech. Torino USA U.C.Berkeley

Collaboration

38

FhG Germany – Sendai city partnership signing ceremonyAnnual Fraunhofer Symposium in Sendai, Project center 2012~

39

Basic

Company

In the past

University

Company University

At present

Company University

In future

Facility for prototypingApplication

Government research institutes

Government research institutes

Government research institutes

40

Efficient development for heterogeneous integration

（MEMS park consortium http://www.memspc.jp）Free MEMS Seminar in Tokyo (Aug. 23-25, 2006) 280 attendees

Free MEMS Seminar in Sendai (Aug. 22-24, 2007) 75 attendees

Free MEMS Seminar in Fukuoka (Aug.20-22, 2008) 150 attendeesFree MEMS Seminar in Nagoya (Aug.4-6, 2009) 100 attendeesFree MEMS Seminar in Tsukuba (Aug.5-7, 2010) 211 attendeesFree MEMS Seminar in Kyoto (Aug.9-11, 2011) 175 attendeesFree MEMS Seminar in Tokyo (Aug.22-24, 2012)

(in The Univ. of Tokyo)

High-tech. small volume production → Job creation

Efficient utilization of facilities

Information from universities

41

Conclusions

1. Multi Band Wireless Communication SystemsMEMS oscillator on LSI (Surface micromachining)

Multiband filter on LSI (Wafer bonding first approach)

PZT switch on LSI (Wafer bonding first approach)

SAW filter on LSI (Wafer bonding last approach)

2. Sensors for SafetyAccelerometer and gyroRange imager using optical scannerTactile sensor network Adhesive bonding

3. Open collaboration for MEMS on LSIShared wafer Massive parallel EB exposure systemsShared facility for industry (Hands-on access fab. )

42

Prof. Assoc.Prof. Prof. Assoc.Prof. Assis.Prof.T.Ono S.Tanaka Y.Haga K.Totsu S.Yoshida

(Nanomachining) (RF MEMS) (Medical) (Hands-on access fab.) (Polymer)

Assis.Prof. Assis.Prof. Assis.Prof. Guest Prof. Assis.Prof.M.Muroyama H.Miyashita Y.Kawai T.Gessner Y.C.Lin (from TW)

(LSI design) (EB exposure) (Piezo electric) (Packaging) (MEMS materials)

Acknowledgment to collaborators FhG ENAS Germany