Ultrasonic transducer, method of producing same, and ultrasonic probe using same
View Patent ↗Disclosed is an ultrasonic transducer that is provided with: a bottom electrode; an electric connection part which is connected to the bottom electrode from the bottom of the bottom electrode; a first insulating film which is formed so as to cover the bottom electrode; a cavity which is formed on the first insulating film so as to overlap the bottom electrode when seen from above; a second insulating film which is formed so as to cover the cavity; and a top electrode which is formed on the second insulating film so as to overlap the cavity when seen from above. The electric connection part to the bottom electrode is positioned so as to not overlap the cavity when seen from above.
1. A method of producing an ultrasonic transducer, the method comprising:
forming a wiring;
forming a first insulating film that covers the wiring;
flattening the first insulating film;
forming, in the first insulating film, a first opening that reaches the wiring;
forming an electric connection part by embedding a conductive film into the first opening;
forming a bottom electrode on the electric connection part;
forming a second insulating film that covers the bottom electrode;
forming a sacrifice layer on the first insulating film at a position where the sacrifice layer overlaps the bottom electrode, but does not overlap the electric connection part;
forming a third insulating film that covers the sacrifice layer;
forming a top electrode on the third insulating film that overlaps the sacrifice layer;
forming a fourth insulating film that covers the top electrode and the third insulating film;
forming a second opening that penetrates the third insulating film and the fourth insulating film to reach the sacrifice layer;
forming a cavity by removing the sacrifice layer using the second opening; and
sealing the cavity by forming a fifth insulating film that covers the opening that reaches the second insulating film and the sacrifice layer.
2. The method of producing the ultrasonic transducer of claim 1 , wherein the forming the electric connection part by embedding the conductive film into the first opening and the forming the bottom electrode on the electric connection part, are performed in one step.
3. The method of producing the ultrasonic transducer of claim 1 , wherein the forming the wiring comprises forming the wiring on a semiconductor substrate.