Ultrasonic transducer cell
An ultrasonic transducer cell according to the present invention includes: a substrate; a charge holding portion provided on the substrate; a lower electrode provided on the charge holding portion and used to input and output a signal; and a vibration membrane provided above the lower electrode to be separated from the lower electrode with a cavity, and configured to include at least an insulating film and an upper electrode provided on the insulating film.
1. An ultrasonic transducer cell comprising:
a substrate;
a lower electrode used to input and output a signal;
a vibration membrane arranged on a first side of the lower electrode, the first side of the lower electrode being opposite to a second side of the lower electrode on which the substrate is arranged, the vibration member being separated from the lower electrode with a cavity and configured to include an insulating film and an upper electrode; and
a charge holding portion formed by charging an insulating material,
wherein the charge holding portion is arranged between the substrate and the lower electrode.
2. The ultrasonic transducer cell according to claim 1 , wherein the charge holding portion is an electret film.
3. The ultrasonic transducer cell according to claim 2 , wherein the electret film is a single-layer film or a multi-layer film, and is made of a silicon compound.
4. The ultrasonic transducer cell according to claim 2 , wherein the electret film is a single-layer film or a multi-layer film, and is made of hafnium oxide.
5. The ultrasonic transducer cell according to claim 2 , wherein the electret film is formed by layering a film made of a silicon compound and a film made of hafnium oxide.
6. The ultrasonic transducer cell according to claim 2 , wherein a second electret film is provided between the lower electrode and the upper electrode.
7. The ultrasonic transducer cell according to claim 1 , wherein the substrate is an insulating substrate configured by an electrically insulating material, and wherein a grounding conductive film having a conductive property and set to the ground potential is provided between the insulating substrate and the charge holding portion.
8. The ultrasonic transducer cell according to claim 2 , wherein the substrate is an insulating substrate configured by an electrically insulating material, and wherein a grounding conductive film having a conductive property and set to the ground potential is provided between the insulating substrate and the charge holding portion.
9. The ultrasonic transducer cell according to claim 1 , wherein the substrate is a conductive substrate configured by a conductive material, and the conductive substrate is set to the ground potential.
10. The ultrasonic transducer cell according to claim 2 , wherein the substrate is a conductive substrate configured by a conductive material, and the conductive substrate is set to the ground potential.
11. The ultrasonic transducer cell according to claim 10 , wherein the conductive substrate is made of a silicon semiconductor.
12. The ultrasonic transducer cell according to claim 9 , wherein the conductive substrate is made of a silicon semiconductor.
13. The ultrasonic transducer cell according to claim 1 , wherein an electrically insulating protective film is provided between the lower electrode and the cavity.
14. The ultrasonic transducer cell according to claim 2 , wherein an electrically insulating protective film is provided between the lower electrode and the cavity.
15. An ultrasonic transducer element comprising the ultrasonic transducer cell according to claim 1 .
16. An ultrasonic transducer array comprising the ultrasonic transducer element according to claim 15 .
17. An ultrasonic diagnostic apparatus comprising the ultrasonic transducer array according to claim 16 .