| Project/Area Number |
60850075
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
計測・制御工学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
MATSUO Tadayuki Department of Engineering Tohoku University, 工学部, 教授 (50005170)
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| Co-Investigator(Kenkyū-buntansha) |
SHOJI Shuichi Department of Engineering Tohoku University, 工学部, 助手 (00171017)
ESASHI Masayoshi Department of Engineering Tohoku University, 工学部, 助教授 (20108468)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 1986: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1985: ¥6,700,000 (Direct Cost: ¥6,700,000)
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| Keywords | Pressure Sensor / Biomedical Application / Capacitive Type Pressure Sensor / Low Drift Micro Fabrication / Silicon-to-Silicon Direct Bonding / 低ドリフト / Si直接接着 / 絶対圧センサ / 圧力 / センサ |
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| Research Abstract |
To develope low drift implantable pressure sensors for biomedical research and clinical use, the fabrication of an absolute capasitive type pessure sensors is studied. The absolute capasitive type pressure sensors are suitable for implantation because of its high pressure sensitivity, low drift and low power consumption. It needs, however, a conplicated process to make two capasitance plates on both side of sealed reference cavity. An capacitance readout circuit is also needed very close to it because of its high output impedance.
The electrostatic bonding of the silicon to the glass plate has been applied to fabricated the capasitive type pressure sensoes. This causes a temperature drift of the sensor due to the strain between the silicon and the glass. A new bonding technique, a direct silicon-to-silicon bonding, which uses polymerization of silanol bonds between wafer pairs is applied for this purpose. A vacuum sealed cavity is easily formed by this method and the CMOS IC can be also formed on the same tip after forming the cavity. The capasitive sensor which has a 500 x 500 <micro> <m^2> and 20 <micro> m thick diaphragm and a 1 <micro> m capasitive gap shows a puressure sensitivity of about 0.1 fF/mmHg.
The capacitance readout circuit which applied a switched capacitor type integrater is designed and fabricated as a CMOS IC. A few fF capasitive deviation can be detected by this circuit. The linearity is guaranteed up to about 2 pF and the power consumption is lower than 0.5mW.
The integration of the sensor and the capacitance readout CMOS IC on the same chip is accomplished. The prssure sensitivity of integrated sensor is about 8 <micro> V/V/mmHg (0.09 fF/mmHg) in the range of 0 to 300 mmHg. The drift of the sensor is, however, a little larger than that expected. This will be improved by redesign the process sequence and the circuit.
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