広島大学ﾅﾉﾃﾞﾊﾞｲｽｼｽﾃﾑ研究ｾﾝﾀｰ講演(第2回，2005.1.25)

マイクロメカニカルフォトニクス

立命館大学 浮田宏生

1. Micromechanical Photonics

– An Emerging Technology –

-1970 : Semiconductor laser diode - late 1980s : Micromachining technology

- early 1990s : Birth of optical MEMS / micromechanical photonics

* digital micromirror device (DMD) for display * optical switches for communication* micro-servo mechanisms for optical/magnetic recording* micro-total analysis systems (µ-TAS) for medical treatment

- Silicon (Si) - Dielectric - Polyimide - Metal

Monolithic integration with an LD

-Group III-V compounds (GaAs, InP) * tunable laser diode: moving external cavity mirror * resonant sensor* optical encoder* integrated flying optical head* blood flow sensor

Remote control in micro/nano scale

- Optical tweezers- Optical pressure rotor

2. Fabrication Methods

2.1 Bulk and surface Micromachining (a) Photolithography(b) Electron beam lithography (EBL)

2.2 Three-dimensional micromachining (a) LIGA(b) Photoforming

2.3 Monolithic Integration with LDs

Al (sacrificed layer)

Si substrate

Resist

Exposure (UV light)

Mask

Development

Mask

Isotropic etching Anisotropic etching

Undercut

(b)(a)

Electron-beam

Exposed partResist

Substrate

10μｍ

50μｍ

10μｍ

50μｍ

Syncrotronradiation

Mask

PMMA resist

Metal substrate

Ni deposition

Mold

Development

StageResin

Objective (NA=0.8)

Half mirror

Lens

CCD

XY scanner

ND filterShutter

ExpanderLaser(473 nm)

PC

10.50.62Lateral232.2Depth

Resolution (µm)

Stacking3-D scanning3-D scanningCubic structureAclyle basedUrethane based Urethane basedResin

0.35 mW1.5 mW50 kW (peak)Power (mW)650442780Wavelength (nm)

LD (DVD head)He-Cd laserTitan-sapphire laserLaserLight source

SpinnerSuper IH processTwo-photon absorptionMethod

スピナー

光ヘッド 樹脂

Ｘステージ

Ｙステージ

Ｚステージ

(b) Entire view

X stage

Y stage

Z stage

Optical head ResinSpinner

Spinner

Optical head

PCXY stage

Resin

(a) Diagram

Microcantilever (MC)Microcantilever

Fig. 1.11

Microcantilever (MC)Microcantilever

(a)

(b)

(c)

(d)

3. Miniaturized Systems with Optics and Mechanics

3.1 Important aspects for miniaturization

3.2 Light processing by micromechanics(a) Free-space optical bench and optical sensors(b) Digital micro-mirror device (DMD) (c) Optical switch(d) Optical head(e) µ-TAS / BioMEMS

3.3 Kinetic energy aspect of light

3.4 Micro mechanical control by optical pressure

【Characteristics of MEMS】- Viscosity >>inertia →Surface force increase- Response time [ L2 ]→ Quick response- Reynolds number [ L2] → Laminated flow- Moving energy [L5 ] → Low energy - Effect on environment → Environmentally friendly

【Technologies of MEMS】- Fabrication: Micromachining- Drive force: Electric, Optic- Material: Silicon, Compound【Optical MEMS】

- Sensor- Switch- µ-TAS

Micromirror (Si plate)

Laser incidence

Laser beam

1 mm

Optical element

Si substrate

Sacrificial layer

Sacrificial layer

Staple holding Staple holding

Si substrate

Optical element

(a) (b)

Side latch

Si substrate

Spring Staple Hing Spring latch

Substrate

ＤＭＤ（構成）

Mirror

Mirror post

Torsion hinge Stopper

Yoke

Bias/reset

To SRAM

Address electrode

ＤＭＤ（作製法）

Metal Sacrificed layer CMP oxide

Hinge mask Hinge metal

Yoke mask Yoke metal

Hinge support post Yoke Hinge

Mirror maskMirror Mirror support post

Mirror Mirror support post

YokeHinge

110 inch

LensDMD chip

Lens

Color filter

Lens

Light source

Screen

Fabrication of micromirror switches

(1) Surface micromachining of polysilicon

- switching 256 input light beams to 256 output fibers (Lucent Technologies)

- 1152 x 1152 optical cross-connects (Nortel)MEMS micromirror array between two stacked PLCs

(2) Bulk micromachining of crystalline silicon

* silicon-on-insulator (SOI) substrate * reactive ion etching (DRIE)

Spring

Ginbalring

Hinged sidewall

Assembly arm

Electrodes

Fixed frame

Base substrate

Torsion springSilicon oxide

Electrode substrate

Pivot

Terraced electrode Ditch

Movable mirror

Ring

AuSnsolder

Mirror

Electrode

Optical disk

LDMicro Fresnel lens

Rotable beam splitterIntegrated PD

450 mirrorSi substrate

Electrostatic actuator

Bow-tie antenna

Springs

Glass substrate

500 µm

Gap

spa

cing

(µm

)Applied voltage (V)

Sample

Reagent

InletMixing

Analysis

Detector

Fluidic channel

LaserObjective

Optical mixer

Microchannel

Sample

Waste

Reagent

Mixing

Outlet

(a) (b)

(a) (b)

4. Integrated Systems with LDs and Micromechanics

4.1 Tunable LD

4.2 Resonant sensor

4.3 Optical encoder

4.4. Flying optical head with an LD

4.5 Blood flow sensor with an LD

4.1 Tunable LD

Antireflection

Tunable LD (LD1)Bimorph

Active layer

Light outputMicro cantilever (MC)

LD exciting a cantilever (LD2)

l

t1 t3t2 t4 t5GaAs or InP

Bimorph films

Au(1)

Si3N4(1)Antireflection films{

Au(2)

Si3N4(2){

b

t1,t2,t3,t4≪t5

Absorption A，Reflectivity R

Au(1) thickness (nm)0 20 40 60 80 100

0

0.2

0.4

0.6

0.8

1.0

16 nm

A

R

Si3N4(1)=366 nm

λ=1.3 µm

Au(1) thickness (nm)0 20 40 60 80 1000

0.2

0.4

0.6

0.8

1.0

26 nm

Si3N4(1)=223 nm

A

R

Absorption A，Reflectivity R

λ=0.83 µm

(a) (b)

Def

lect

ion

(nm

)

Thickness of Au(2) film (nm)

Au(1) /Si3N4(1) /Au(2) /Si3N4

(2) /InP

50 100 150

200

400

600

800

1000

00

78

415

650

81

200

Au(1) /Si3N4(1) /Au(2) /Si3N4

(2) /GaAs

Lex Optical disk

Flying slider LD-PD

Lex

Lex

Optical spectrum analyzer

Lens

Optical fiber

Rotation direction

External cavity1

0

1278

1285

1292

1299

1306

1313

1.7 2.0 2.3 2.6 2.9

外部共振器長 [μm]

波長

[nm

]

②

①

③

④⑥

⑤⑦

⑧

①～⑧の発振スペクトル

波長 [μm]

①

波長 [μm]

⑤

波長 [μm]

②

波長 [μm]

③

波長 [μm]

④

波長 [μm]

⑥

波長 [μm]

⑦

4.2 Resonant sensor

4.3 Optical encoder

Mirror

Photo diode

Microlens

U-shaped LD

Scale Pitch Λ

Gap

4.4. Flying optical head with an LD

4.5 Blood flow sensor with an LD

5. Future Outlook of Optical MEMS

and Micromechanical Photonics

Kinds of force Silicon Dielectric, Polymer, Metal III-V Compound OthersQuartz Polyimide, resin (GaAs, InP)

OpticalOptical Pressure Rotor, M (62) Rotor, (63) Near field probe, (19)

Rotor, P (64)Rotor, P (65)Mixer, M (50,66)

Photoelectric Solar cell, M (57,58) Encoder, I (68)Near field probe, M (74) Blood flowmeter, I (70)

Photothermal Gripper, P (54) Switch, M (55) Tunable LD, I (67)Resonator, I (17)Optical head, I (69)

Photoelectrochemical Battery, O (56)Electrostatic Slider, M (8) Antenna, M (35) Pump, M (12) DMD, M (5) Tunable LD, I (16)

Optical head, I (20) Mirror, M (34) Tunable PD, I (15)Bow-tie probe, M (46)Switch, M (6,7)Switch, M (40,41)Focal length controlShutter, M (76)XYZ stage, M (38)Micro-pump, M (52)Diagnosis probe, M (53)

Electromagnetic Scanner, M (33)Tunable filter, L (29)

Piezoelectric Nano-tracking, M (9)Valiable focal length lens, M (77)

Others Microchannels, M (49)Micro-TAS, M (48)

M: Micromachining including lithography, etching, sputtering and deposition, P: Photoforming, L: LIGA, I: Monolithic integration of a laser diode, O: Others.

Optical MEMS size

Molecular device

1.0 m 1.0 mm 1.0 µm

3

5

7

9

11

Optical disk

Acutuator

Alignment

In commercial

Under development

Pressure sensorAccelerometer

1

MDF

ResonatorEncoder

Surface actuator

Scanner

Fiber connector

DMD

MotorTunable LD

IR sensor

Rotor/Mixer

Num

ber o

f fun

ctio

n

Blood flowmeter

µ-TASSwitch

Pump

Diagnosisprobe

Bow tieprobe