Application oriented micro-nano electro mechanical systems

Masayoshi Esashi

New Industry Creation Hatchery Center, Tohoku University, Sendai, Japan

Ⅰ. Introduction

Ⅱ. Electrostatically levitated rotational gyroscope

Ⅲ. MEMS relay

Ⅳ. Multi probe data storage

Ⅴ. Electron field emitter array using carbon nanotube for multi-column electron beam lithography

Ⅵ. Monolithic stage

Ⅶ. Micro Molding for Harsh Environment

A. Silicon lost mold process for SiC microstructure

B. SiC microstructures for glass press molding

Ⅷ.Conclusions

MEMS process facility for 20 mm wafer

Vibrating gyroscope (yaw rate sensor) for vehicle stability control

Resonating gyroscope fabricated using Si deep RIE

Si deep RIE system(M.Takinami, 11th Sensor Symposium, (1992) p.15)

Ⅱ. Electrostatically levitated rotational gyroscope

Electrostatically levitating micromotor for rotational gyroscope (disk rotor type)

(T.Murakoshi (Tokimec Inc.) et.al., Transducers’99)

Electrostatically levitating micromotor for rotational gyroscope (disk rotor type)

(T.Murakoshi (Tokimec Inc.) et.al., Transducers’99)

10mm

Electrostatically levitating micromotor for rotating gyroscope

Max 20,000 rpm5mm

Rotor position is capacitively detected and voltage is applied to electrode

(T.Matsubara et.al., Transducers’93, 50-53)

Electrostatically levitating micromotor for rotational gyroscope (ring rotor type) (Control voltage < 15 V)(T.Murakoshi et.al. : Jpn. J. Appli. Phys., 42, Part1 No.4B (2003) pp.2468-2472)

Structure of electrostatically levitated ring rotor gyroscope

Fabrication process of electrostatically levitating micromotor for rotational gyroscope (ring rotor type)

Rotor

Gap 5μm(100μm deep)

Lateral control electrode

4mm ring : 12,000 rpm (1mm ring : 100,000 rpm)

Inertia measurement system for 2-axis rotation and 3-axis acceleration

Noise floor

Gyro : 0.002 deg/s/√Hz

Accelerometer ： 10μG/ √Hz

Rotor

MESAG-1 (Micro Electrostatically Suspended Accelerometer Gyro)

Integrated capacitive pressure sensor

Circuit integration

(T.Kudoh et.al., Sensors and Actuators A,29 (1991) p.185-193)

MEMS is value added but small volume

→ Hard to commercialize because of

the high cost.

(70% of the MEMS cost is packaging

and test)

Wafer level packaging

→ low cost (minimization of assembly

investment and loss in test)

→ small size (chip size encapsulation)

→ high yield (protection of MEMS

structures during dicing)

→ reliability (hermetic sealing)

MEMS relay having electrical feedthrough made by RIE and electroplating (Y.Liu et.al., MEMS’01)

Partly removed

Micro spring contact

Packaged micro relay

High reliability (>107)

Application for LSI tester

(A.Nakamura et.al.,Advantest Technical Report, 22 (2004), 9-16)

5mm4mm

Driving power <160mW (6V)

On resistance <0.3Ω

Operation speed

<3ms

Life of contact 8×107（ 3V-15mA）>20GHz

Multi probe data storage　　 Conventional hard disk

Ⅳ. Multi probe data storage

Structure of the multiprobe data storage (D.W.Lee et.al., J. of Microelectromechanical Systems, 11, 3 (2002), 215-219)

Recording media

Conductance image of the recorded bits on thin GeSbTe (phase change media) (2m2m)

Diamond Probe for Ultra-High-Density Data Storage Based on Scanning Nonlinear Dielectric Microscopy

(H.Takahashi (Pioneer Corp.), T.Ono, Y.Cho and M.Esashi (Tohoku Univ.) MEMS’04 (2004) p.536)

N S + +-

Domain of ferromagnetics Domain of ferroelectrics

Pr

Pr

Pr

Bloch wall~50nm

Single lattice domain wall

Advantageous to record nano-size domain array

N

N

SNDM 　 (Scanning Nonlinear Dielectric Microscopy)

(Y.Cho, Rev. Sci. Instrum. 67, (1996) p.2297)

The diamond probe array.

The end of the diamond probe. 800nm

Recording medium

LiTaO3 Thickness: 60nmWriting condition

DC Pulse: 15 V Width: 1 ms

Reading condition

AC voltage: 2.5V Frequency: 10kHz

FM signal frequency: around 1.3GHz

Conductance modification of conductive polymer

(T.Ono et.al., Nanotechnology, 14 (2003) pp.1051-1054)

(T.Ono et.al., Nanotechnology, 14 (2003) pp.1051-1054)

・ Scan speed　10m/sec

・ Recording voltage　10V

・ Reading voltage　　0.4V

Dot diameter　150nm

Recording on a conductive polymer (doped polyaniline) film

Conductance is decreased by 20 times after recording.

Current image (5m×5m)

Current after writing

Ⅴ. Electron field emitter array using carbon nanotube for multi-column electron beam lithography

Concept of Multi-Column Electron Beam Lithography

Electron field emitter array with electrostatic lens

(P.N.Minh, MEMS’04

(2004), p.430)

Fabrication of electron field emitter array with electrostatic lens

CNT electron field emitter

Hot filament CVD of carbon nano tube

(H.Miyashita et.al. MEMS'2001)

Electron field emitter with carbon nano tube deposited at the Si apex

(P.H.Minh et.al. , J. Vac. Sci. Technol. B 21, 4, (2003), 1705-1709)

Effect of hydrogen treartment (Fowler-Nordheim plot)

Stability of carbon nanotube field emitter

Ⅵ. Monolithic stage

Monolithic stage fabricated from a PZT plate

(D.-Y.Zhang et.al., Digest of Technical Papers, Transducers'03, Boston (2003) 1518-1521)

Monolithic X-Y stage

X/Y Motion

Amplification factor L/W

Rotation around Z axis Z motion

Elongation vs. Applied Voltage of bimorph PZT actuator

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 20 40 60 80 100 120Applied Voltage (V)

Dis

pla

cem

ent

(um

)

L

Z

-12.0

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

0 20 40 60 80 100 120

Dis

pla

cem

ent

(um

)

Applied Voltage (V)

Bending vs. Applied Voltage of bimorph PZT actuator

Ⅶ. Micro Molding for Harsh Environment

A. Silicon lost mold process for SiC microstructure

B. SiC microstructures for glass press molding

Si lost mold process for SiC microstructure.

(reaction sintering condition : 1700°C, 100MPa)(S.Sugimoto et.al., MEMS’2000)

SiC micro turbine made by the Si lost mold process

Gray scale exposure by exposing with programmed multiple patterns Surface profile of resist

Mask less exposure system using DMD (Ball Semiconductor INC.)

Micro lens array fabricated

(K.Totsu et.al., Sensor Symposium, Late news (2004/10/14))Gray scale mask-less exposure

Fabrication of SiC mold for glass mold press (T.Itoh et.al., Transducers'03, (2003) p.25

4)

SiC mold for glass mold press

(non-spherical lens)(K.-O.Min et.al.,The 21th Sensor Symposium, Kyoto (2004/10/14-15))

Wafer level packaging

Multiprobe data storage

Electrical feedthrough in glass

MEMS relay

SIP (System In Package) MEMS

Ⅷ.Conclusions

SiC mold for glass mold press

Electrostatically levitated rotational gyroscope

Monolithic stage