Ultrasonic transducer and manufacturing method thereof

1. An ultrasonic transducer, comprising:

a first electrode;

a second electrode;

an insulating film disposed between the first and second electrodes; and

a cavity disposed between the first and second electrodes;

wherein the insulating film includes a projection extending in the cavity;

wherein a portion of the cavity is disposed between the projection and the first electrode; and

wherein a portion of at least one of the first electrode and the second electrode has an opening corresponding to a position of the projection of the insulating film when viewed in plan view.

2. The ultrasonic transducer of claim 1 , wherein the second electrode is disposed over the first electrode.

3. The ultrasonic transducer of claim 2 , further comprising:

a second insulating film disposed between the first electrode and the cavity.

4. The ultrasonic transducer of claim 2 , further comprising:

a third insulating film disposed over the second electrode.

5. The ultrasonic transducer of claim 1 , wherein a distance between an outer peripheral surface of the projection and an inner peripheral surface of the opening in at least one of the first electrode and the second electrode is greater than a thickness of the insulating film.

6. An ultrasonic transducer comprising:

a first electrode;

a second electrode including an opening;

a cavity disposed between the first and second electrodes;

an insulating film, disposed between the first and second electrodes including a projection corresponding to a position of the opening when viewed in plan view; and

a cavity disposed between the first and second electrodes so that a portion of the cavity is disposed between the projection and one of the first and second electrodes.

7. The ultrasonic transducer of claim 6 , wherein the second electrode is disposed over the first electrode.

8. The ultrasonic transducer of claim 7 , further comprising:

a second insulating film disposed between the first electrode and the cavity.

9. The ultrasonic transducer of claim 7 , further comprising:

a third insulating film disposed over second electrode.

10. The ultrasonic transducer of claim 6 , wherein a distance between an outer peripheral surface of the projection and an inner peripheral surface of the opening in at least one of the first electrode and the second electrode is greater than a thickness of the insulating film.

11. An ultrasonic transducer, comprising:

a first electrode;

a cavity disposed over the first electrode;

an insulating film disposed over the first electrode; and

a second electrode disposed over the cavity;

wherein the insulating film includes a projection extending in the cavity so that a portion of the cavity is disposed between the projection of the insulating film and the first electrode; and

wherein at least a portion of at least one of the first electrode and the second electrode has an opening corresponding to a position of the projection of the insulating film when viewed in plan view.

12. The ultrasonic transducer of claim 11 , further comprising:

a second insulating film disposed between the first electrode and the cavity.

13. The ultrasonic transducer of claim 11 , further comprising:

a third insulating film disposed over the second electrode.

14. The ultrasonic transducer of claim 11 , wherein a distance between an outer peripheral surface of the projection and an inner peripheral surface of the opening in at least one of the first electrode and the second electrode is greater than a thickness of the insulating film.