Micro-electro-mechanical device for transducing high-frequency acoustic waves in a propagation medium and manufacturing process thereof

A method, comprising:

• forming a Piezoelectric Micromachined Ultrasonic Transducer (PMUT) acoustic transducer including:
• forming a plurality of first buried cavities in a wafer of semiconductor material, the first buried cavities being arranged concentrically to each other and extending at a distance from the face of the first wafer,
• the first buried cavities defining a plurality of first membranes each extending between a respective first buried cavity of the plurality of first buried cavities and the face of the body;
• and
• forming a plurality of piezoelectric elements on the face of the body, each piezoelectric element extending above a respective first membrane of the plurality of first membranes;
• wherein the first membranes have different widths.

A device, comprising:

• a body of semiconductor material having a face;
• a plurality of annular buried cavities in the body of the semiconductor material, each annular buried cavity of the plurality of annular buried cavities is concentric with each other, and the plurality of annular buried cavities is at a first level within the body;
• a plurality of annular piezoelectric elements on the face of the body, each one of the annular piezoelectric elements of the plurality of annular piezoelectric elements overlaps a corresponding annular buried cavity of the plurality of annular buried cavities;
• a round piezoelectric element on the face of the body and surrounded by the plurality of annular piezoelectric elements;
• a first round buried cavity in the body of the semiconductor material, the first round buried cavity overlaps the round piezoelectric element, and the first round buried cavity is at the first level within the body;
• and
• a second round buried cavity in the body of the semiconductor material, the second round buried cavity overlaps the first round buried cavity and at least one annular buried cavity of the plurality of annular buried cavities, and the second round buried cavity is at a second level within the body different from the first level.