Ultrasonic probe and method for manufacturing the same and ultrasonic diagnostic device

An ultrasonic probe comprising:

• a Capacitive Micromachined Ultrasonic Transducer (cMUT) chip having a plurality of vibration elements whose electromechanical coupling coefficient or a sensitivity changes depending on a bias voltage, and configured to transmit/receive an ultrasonic wave to/from a subject;
• an acoustic lens provided on an ultrasonic wave radiation side of said cMUT chip;
• a backing layer provided on a back side of said cMUT chip, to absorb a propagation of said ultrasonic wave;
• an electric wiring portion provided from a peripheral portion of said cMUT chip and on a side surface of said backing layer and having a signal pattern connected with an electrode of said cMUT chip arranged thereon;
• and
• a housing for containing said cMUT chip, acoustic lens, said backing layer and said electric wiring portion,
• wherein:
• a ground layer at ground potential surrounds the ultrasonic wave radiation side of said cMUT chip and side surfaces of said cMUT chip and said electrical wiring portion, to cover said cMUT chip and said side surfaces of said electrical wiring portion as a grounding barrier to not allow electricity in the ultrasonic probe to discharge to the subject;
• said cMUT chip has a substrate;
• each of said vibration elements of said cMUT chip has a film body provided on the ultrasonic radiation side of said substrate of said cMUT chip, a lower electrode provided in said film body, and an upper electrode provided on the ultrasonic radiation side of said lower electrode;
• said substrate of cMUT chip is connected with a ground line;
• AC high frequency voltage for transmitting/receiving ultrasonic wave is applied on said upper electrode using ground potential as reference potential;
• and
• DC bias voltage for changing electromechanical coupling coefficient or sensitivity of said vibration element is applied on said lower electrode using ground potential as reference potential.