Capacitive ultrasonic transducer, production method thereof, and capacitive ultrasonic probe

A production method of a capacitive ultrasonic transducer which comprises a first electrode, a second electrode which faces the first electrode and is arranged with keeping a predetermined gap, and a high dielectric constant film which is given on a surface of at least one electrode of the electrodes, that is, the surface which faces another one of the electrodes, comprising:

• a stacked layer forming step of performs stacked layer formation of one or more layers including the first electrode and high dielectric constant film on a first substrate;
• a cavity forming step of forming cavities in a second substrate for forming the cavities which are spaces between the first electrode and the second electrode;
• an electrode forming step of forming a second electrode in bottom sections of the cavities;
• a bonding step of bonding a surface in a stacked layer formation side of the first substrate, on which the stacked layer formation is performed, with a convex section surface of the second substrate;
• and
• a substrate removing step of removing the first substrate from the first substrate on which the stacked layer formation is performed.

A production method of a capacitive ultrasonic transducer which comprises a first electrode, a second electrode which faces the first electrode and is arranged with keeping a predetermined gap, and a high dielectric constant film which is given on a surface of at least one electrode of the electrodes, that is, the surface which faces another one of the electrodes, comprising:

• a substrate forming step of not only forming cavities in a second substrate for forming the cavities which are spaces between the first electrode and the second electrode, but also forming the second electrode in the bottom sections of the cavities;
• a sacrifice layer forming step of forming a sacrifice layer by making the cavities of the second substrate filled with a resist agent;
• a high dielectric constant film forming step of forming one or more films, including the high dielectric constant film, on a surface of a side of the second substrate where is filled with the resist agent;
• an electrode forming step of forming the first electrode on the film;
• and
• a sacrifice layer removing step of making holes penetrate the first electrode and the film, and removing the sacrifice layer from the holes.

A production method of a stacked capacitive ultrasonic transducer, not only comprising:

• a first step of forming an insulating layer on an upper face of a semiconductor substrate and forming a first electrode layer on its upper face;
• a second step of forming a temporary layer for cavity formation on an upper face of this first electrode layer;
• a third step of forming masks corresponding to portions, where cavities are formed, on the temporary layer so as to make them arranged two-dimensionally;
• a fourth step of forming concavities reaching the first electrode layer by removing portions, to which the masks are not given, by etching and the like;
• a fourth step of removing the masks and exposing the temporary layer;
• a fifth step of forming a film covering the temporary layer while filling the concavities;
• a sixth step of forming holes which penetrate the film and reach the temporary layer;
• a seventh step of removing the temporary layer by etching or the like using the holes;
• an eighth step of forming a membrane layer on an upper face of the film;
• a ninth step of forming a second electrode layer on an upper face of the membrane layer;
• and
• a tenth step of repeating the second step to ninth step once or more on the second electrode layer,
• but also forming upper side masks with shifting them so as to become positions between two just lower layers of masks when forming them at that time.

A production method of a capacitive ultrasonic transducer, produced by:

• a first step of forming a spherical surface or an aspherical surface near a spherical surface in one surface of a substrate;
• a second step of forming a further finer concave work surface with leaving a part of a region of the spherical surface or the aspherical surface near a spherical surface;
• a third step of forming a lower electrode in a surface which is not the further finer concave work surface, after the second step;
• and
• a fourth step of bonding a flexible sheet, which is given an upper electrode on the lower electrode and can be vibrated, after the third step.