MEMS and Industry-University CollaborationMasayoshi Esashi
Department of Nanomechanics, Tohoku University, Sendai, Japan
1. Introduction 2. Gyroscope3. Wafer level packaging and electrical feedthrough4. Multi probe data storage and monolithic stage5. Multi-column electron beam lithography system6. Micro-Nano mold press 7. MEMS for power supply 8. Small volume supply of MEMS
ＩＳＦＥＴ(Ion Sensitive FET)（T.Matsuo, M.Esashi, K.Iinuma, Tohoku region meeting of Electrical Eng. (1971)）
ISFET (Ion Sensitive Field Effect Transistor)(M.Esashi, Supplement to the J.J.AP.,44 (1975),339-343)
Catheter tip pH、PCO2 sensor(K.Shimada et.al., Med.& Biol.Eng. & Comput.,18 (1980))
pH、PCO2 monitor catheter using ISFET
Integrated blood analysis system(S.Shoji et.al., Sensors and Actuators, 14 (1988) pp.101-107)
Antibody H.pyloripH change by ammonia (reaction product) is measured using the ISFET
Urea
H.pylori detector using ISFET (H.pylori causes stomach ulcer)
Portable pHmeter
MEMS process facility for 20 mm wafer (users : 25 laboratories)
Dr.Ono (Nanomachining) Dr.Tanaka (Power MEMS) Dr.Totsu (Catheter sensor)
Staff 4 and Pos-doc 2
Students Dr.13, Mr.10 and Undergraduate students 5
Dispatched researchers from industry Full time 10 and Part time 17
(Foreign people 21： Korea 7, China 5, Taiwan 3, Germany 3, USA 2, Canada 1)
2. Gyroscope
Resonating gyroscope
Electrostatically levitated rotational gyroscope
Vibrating gyroscope (yaw rate sensor) for vehicle stability control
1992-1997Two researchers from Toyota stayed in Tohoku University for collaborative development of vibrating gyroscope
Resonating gyroscope fabricated using Si deep RIESi deep RIE system
(M.Takinami, 11th Sensor Symposium, (1992) p.15)
Semiconductor Capacitance Type Accelerometer with Electrostatic Servo Controller(S.Suzuki, S.Tuchitani, K.Sato, Y.Yokota, M.Sato and M.Esashi
Sensors and Actuators,A21-23,(1990))
Electrostatic servo capacitive 3-axis accelerometer(Johno et.al., MEMS’94 )
Principle of electrostatic levitation
Electrostatically levitated spherical 3-axis accelerometer
(R.Toda (Ball Semiconductor Inc.) et.al., MEMS’02)
Example of 3-axis acceleration measurement using ball accelerometer
-1.0
-0.5
0.0
0.5
1.0ca
libra
ted
outp
ut [G
]
-180 -90 0 90 180rotation angle about y-axis [deg]
x y z
Projection exposure system using DMD
Maskless exposure sytemElectrode pattern made on a 1mm diameter Si ball
Electrostatically levitating micromotor for rotational gyroscope (disk rotor type) (T.Murakoshi (Tokimec Inc.) et.al., Transducers’99)
Electrostatically levitating rotational gyroscope(disk rotor type) (T.Murakoshi (Tokimec Inc.) et.al., Transducers’99)
10mm
20,000 rpm
Rotor position is capacitivelydetected and voltage is applied to electrode(T.Matsubara et.al., Transducers’93, 50-53)
Rotor
Control Electrodes for z and θ (or φ) axis
Control Electrodes for x (or y) axis
Pad
Rotation Electrodes
Common Electrodes
Island (Feedthrough)
Structure of electrostatically levitaed rotational gyroscope(T.Murakoshi et.al. : Jpn. J. Appli. Phys., 42, Part1 No.4B (2003) pp.2468-2472)
1.5 mm
Rotational gyroscope levitated electrostatically using high speed digital signal control
MESAG-1 (Micro Electrostatically Suspended Accelerometer Gyro)(Simultaneous measurement of 2 axes rotation and 3 axes acceleration)
(Tokimec Corp., T.Murakoshi)
Rotor diameter1.5mm 74,000rpm4.3×4.3×1mm
14×14×3mm
Fabrication process of the electrostatically levitaed rotational gyroscope
Performance of of electrostatically levitaed rotational gyroscope
GyroscopeRange: ±150 deg/s
Sensitivity(1LSB): 0.01 deg/s
Noise：0.002 deg/s/√Hz
Offset in temp.range: ±1 deg/s
AccelerometerRange: ±5 G
Sensitivity(1LSB): 0.2 mG
Noise：50 μG/√Hz
Offset in temp.range: ±10 mG
Temp. range: -40－85 ℃
3. Wafer level packaging and electrical feedthrough
Wafer level packaging
MEMS relay
Contactor for wafer probing
Electrical interconnection through Si wafer
Integrated capacitive pressure sensorCircuit integration
(T.Kudoh et.al., Sensors and Actuators A,29 (1991) p.185-193)
Capacitance detection circuit (JTEKT 2006~)
MEMS is value added but small volume
→ Hard to commercialize because of the high cost.
(70% of MEMS cost : packaging, 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)→ small loss in test after packaging
Silicon diaphragm capacitive vacuum sensor(K.Hatanaka et.al., 13th Sensor Symposium, 1995)
Vacuum packaging
