| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic sensor in which sensitivity can be enhanced by reducing variation in sensitivity of the sensor. SOLUTION: An ultrasonic sensor 100 comprises a substrate 110 in which a thin portion 120 is formed partially; and a piezoelectric vibrator 130 formed on the thin portion 120 and having a piezoelectric thin film 131 arranged between two detection electrodes 132 and 133, and arranged such that a membrane structure consisting of the thin portion 120 and the piezoelectric vibrator 130 resonates at a predetermined frequency. Internal stress of the entire membrane structure is adjusted to become tensile stress or zero, and a part of the membrane structure is constituted as a compressive stress in the plane direction of the substrate 110. COPYRIGHT: (C)2008,JPO&INPIT
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