A piezoelectric micromachined ultrasonic transducer (PMUT) includes a substrate, a stopper, and a membrane, where the substrate and the stopper are composed of same single-crystalline material. The substrate has a cavity penetrating the substrate, and the stopper protrudes from a top surface of the substrate and surrounds the edge of the cavity. The membrane is disposed over the cavity and attached to the stopper.

There is provided a method for producing a piezoelectric element, which allows for forming a columnar microstructure with a small width and a high aspect ratio. The method is intended to produce a piezoelectric element 102 including a three-dimensional structure group 20 having a plurality of the three-dimensional structures 21 and 321 formed in a plate-like or columnar shape with a width of 30 μm or less and a height of 80 μm or more. The production method includes a first process of fabricating a plurality of plate-like or columnar precursor shapes 82a on a bulk material 81 formed of a Pb-based piezoelectric material, and a second process of reducing the width of the precursor shapes 82a to a predetermined value using an etching liquid.

Disclosed is a vibration actuator device. The vibration actuator device includes a substrate, lower supports disposed on the substrate and spaced apart from each other in a first direction, an actuator disposed on the lower supports to generate a vibration having a first resonant frequency by an external power, a vibration plate disposed on the actuator to vibrate in accordance with the actuator, and a mass portion disposed on the vibration plate to vibrate in accordance with the actuator and the vibration plate. Here, each of the vibration plate and the mass portion has a second resonant frequency that is less than the first resonant frequency.

A micro-electro-mechanical systems (MEMS) sensor includes a substrate, a diaphragm portion and a piezoelectric film. The diaphragm portion is located at the substrate. The piezoelectric film is located on the diaphragm portion. The piezoelectric film is made of scandium aluminum nitride. A carbon concentration of the piezoelectric film is 2.5 atomic percent or less while an oxygen concentration of the piezoelectric film is 0.35 atomic percent or less.

An ultrasonic device includes an ultrasonic element configured to perform at least one of transmission of an ultrasonic wave along a first axis and reception of the ultrasonic wave input along the first axis, and a protective member provided on the first axis to cover the ultrasonic element. The protective member has a first surface provided with at least one hole through which the ultrasonic wave travelling along the first axis passes, and a second surface intersecting with the first surface and provided with a first opening through which foreign matter entering from the at least one hole is discharged.

MEMS ultrasonic transducer, MUT, device, comprising a semiconductor body with a first and a second main surface and including: a first chamber extending into the semiconductor body at a distance from the first main surface; a membrane formed by the semiconductor body between the first main surface and the first chamber; a piezoelectric element on the membrane; a second chamber extending into the semiconductor body between the first chamber and the second main surface; a central fluidic passage extending into the semiconductor body from the second main surface to the first chamber and traversing the second chamber; and one or more lateral fluidic passages extending into the semiconductor body from the second main surface to the second chamber. The one or more lateral fluidic passages, the central fluidic passage and the second chamber define a fluidic recirculation path that fluidically connects the first chamber with the outside of the semiconductor body.

Microelectromechanical (MEMS) devices and associated methods are disclosed. Piezoelectric MEMS transducers (PMUTs) suitable for integration with complementary metal oxide semiconductor (CMOS) integrated circuit (IC), as well as PMUT arrays having high fill factor for fingerprint sensing, are described.

An electroacoustic transducer comprising an electromechanical transducer and a vibratory component. The latter has a generally cylindrical side wall, an outwardly directed portion at the base of the side wall, and a generally planar vibratory top wall extending inwardly from the rim of the side wall further from its base to close the upper end of the cylindrical side wall. The said outwardly directed portion is mounted on the electromechanical transducer.

A PMUT includes a substrate, a stopper, and a multi-layered structure, where the substrate includes a corner, and a cavity is disposed in the substrate. The stopper is in contact with the corner of the substrate and the cavity. The multi-layered structure is disposed over the cavity and attached to the stopper and the multi-layered structure includes at least one through hole in contact with the cavity.

An ultrasonic sensor includes an opening portion, vibrating plate covering the opening portion, piezoelectric element overlapping with the opening portion, and a coupling electrode coupled to the piezoelectric element, extended from a position overlapping the opening portion to a position not overlapping the opening portion, and having a line width smaller than a width of the piezoelectric element. The piezoelectric has a first and second line portion, and a corner portion coupling the first and second line portions, when an intersection point connects a center of gravity of the piezoelectric and the corner portion with a virtual circle inscribed in the outline of the piezoelectric is a first intersection point of a tangent line. The first intersection point with the first and second line portions are a second and third intersection points, the coupling electrode coupled to a corner portion from the second intersection point to the third intersection point.