MEMS and Industry-University Collaboration Masayoshi Esashi Department of Nanomechanics, Tohoku University, Sendai, Japan 1. Introduction 2. Gyroscope 3. Wafer level packaging and electrical feedthrough 4. Multi probe data storage and monolithic stage 5. Multi-column electron beam lithography system 6. Micro-Nano mold press 7. MEMS for power supply 8. Small volume supply of MEMS
(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 PCO 2 sensor (K.Shimada et.al., Med.& Biol.Eng. & Comput.,18 (1980))
ph PCO 2 monitor catheter using ISFET
Integrated blood analysis system (S.Shoji et.al., Sensors and Actuators, 14 (1988) pp.101-107)
Portable ph meter Antibody H.pylori ph change by ammonia (reaction product) is measured using the ISFET Urea H.pylori detector using ISFET (H.pylori causes stomach ulcer)
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
1992-1997 Two researchers from Toyota stayed in Tohoku University for collaborative development of vibrating gyroscope 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)
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)
1.0 calibrated output [G] 0.5 0.0-0.5-1.0 x y z -180-90 0 90 180 rotation angle about y-axis [deg] Example of 3-axis acceleration measurement using ball accelerometer
Projection exposure system using DMD Electrode pattern made on a 1mm diameter Si ball Maskless exposure sytem
Electrostatically levitating micromotor for rotational gyroscope (disk rotor type) (T.Murakoshi (Tokimec Inc.) et.al., Transducers 99)
20,000 rpm 10mm Electrostatically levitating rotational gyroscope (disk rotor type) (T.Murakoshi (Tokimec Inc.) et.al., Transducers 99)
Rotor position is capacitively detected and voltage is applied to electrode (T.Matsubara et.al., Transducers 93, 50-53)
Control Electrodes for x (or y) axis Rotation Electrodes Rotor Island (Feedthrough) Common Electrodes Pad Control Electrodes for z and θ (or φ) axis 1.5 mm Structure of electrostatically levitaed rotational gyroscope
4.3 4.3 1mm Rotor diameter1.5mm 74,000rpm 14 14 3mm Rotational gyroscope levitated electrostatically using high speed digital signal control (Tokimec Corp., MESAG-1 (Micro Electrostatically Suspended Accelerometer Gyro) (Simultaneous measurement of 2 axes rotation and 3 axes acceleration) T.Murakoshi)
Fabrication process of the electrostatically levitaed rotational gyroscope
Gyroscope Accelerometer Temp. range: -40 85 Performance of of electrostatically levitaed rotational gyroscope
3. Wafer level packaging and electrical feedthrough Wafer level packaging MEMS relay Contactor for wafer probing Electrical interconnection through Si wafer
Capacitance detection circuit (JTEKT 2006~) 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 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
Vacuum packaging Silicon diaphragm capacitive vacuum sensor (K.Hatanaka et.al., 13th Sensor Symposium, 1995)