A sound producing package structure includes a first sub-package structure and a second sub-package structure. The first sub-package structure includes a first substrate having a first opening and a first chip including a first membrane, wherein a first cavity is formed between the first membrane and the first substrate. The first sub-package structure and the second sub-package structure are stacked, and the second sub-package structure includes a second substrate and a second chip. The second substrate is connected to the first substrate and has a second opening. The second chip includes a second membrane, wherein a second cavity is formed between the second membrane and the second substrate. A gap, connected to the first opening and the second opening, is formed between the first substrate and the second substrate, such that an ambient of the sound producing package structure, the first cavity and the second cavity are connected.

In some embodiments, a piezoelectric biosensor is provided. The piezoelectric biosensor includes a semiconductor substrate. A first electrode is disposed over the semiconductor substrate. A piezoelectric structure is disposed on the first electrode. A second electrode is disposed on the piezoelectric structure. A sensing reservoir is disposed over the piezoelectric structure and exposed to an ambient environment, where the sensing reservoir is configured to collect a fluid comprising a number of bio-entities.

An elastic wave device includes a supporting substrate, a high-acoustic-velocity film stacked on the supporting substrate and in which an acoustic velocity of a bulk wave propagating therein is higher than an acoustic velocity of an elastic wave propagating in a piezoelectric film, a low-acoustic-velocity film stacked on the high-acoustic-velocity film and in which an acoustic velocity of a bulk wave propagating therein is lower than an acoustic velocity of a bulk wave propagating in the piezoelectric film, the piezoelectric film is stacked on the low-acoustic-velocity film, and an IDT electrode stacked on a surface of the piezoelectric film.

A wafer level ultrasonic chip module includes a substrate, a composite layer, a conducting material, and a base material. The substrate has a through slot that passes through an upper surface of the substrate and a lower surface of the substrate. The composite layer includes an ultrasonic body and a protective layer. A lower surface of the ultrasonic body is exposed from the through slot. The protective layer covers the ultrasonic body and a partial upper surface of the substrate. The protective layer has an opening, from which a partial upper surface of the ultrasonic body is exposed. The conducting material is in contact with the upper surface of the ultrasonic body. The base material covers the through slot, such that a space is formed among the through slot, the lower surface of the ultrasonic body and an upper surface of the base material.

In some embodiments, a piezoelectric biosensor is provided. The piezoelectric biosensor includes a semiconductor substrate. A first electrode is disposed over the semiconductor substrate. A piezoelectric structure is disposed on the first electrode. A second electrode is disposed on the piezoelectric structure. A sensing reservoir is disposed over the piezoelectric structure and exposed to an ambient environment, where the sensing reservoir is configured to collect a fluid comprising a number of bio-entities.

An elastic wave device includes a supporting substrate, a high-acoustic-velocity film stacked on the supporting substrate and in which an acoustic velocity of a bulk wave propagating therein is higher than an acoustic velocity of an elastic wave propagating in a piezoelectric film, a low-acoustic-velocity film stacked on the high-acoustic-velocity film and in which an acoustic velocity of a bulk wave propagating therein is lower than an acoustic velocity of a bulk wave propagating in the piezoelectric film, the piezoelectric film is stacked on the low-acoustic-velocity film, and an IDT electrode stacked on a surface of the piezoelectric film.

A MEMS actuator includes a monolithic body of semiconductor material, with a supporting portion of semiconductor material, orientable with respect to a first and second rotation axes, transverse to each other. A first frame of semiconductor material is coupled to the supporting portion through first deformable elements configured to control a rotation of the supporting portion about the first rotation axis. A second frame of semiconductor material is coupled to the first frame by second deformable elements, which are coupled between the first and the second frames and configured to control a rotation of the supporting portion about the second rotation axis. The first and second deformable elements carry respective piezoelectric actuation elements.

An ultrasonic transducer device for use in an acoustic biometric imaging system, the ultrasonic transducer device comprising: a first piezoelectric element having a first face, a second face opposite the first face, and side edges extending between the first face and the second face; a first transducer electrode on the first face of the first piezoelectric element; a second transducer electrode on the second face of the first piezoelectric element; and a spacer structure leaving at least a portion of the first transducer electrode of the first piezoelectric element uncovered.

The MEMS actuator is formed by a substrate, which surrounds a cavity; by a deformable structure suspended on the cavity; by an actuation structure formed by a first piezoelectric region of a first piezoelectric material, supported by the deformable structure and configured to cause a deformation of the deformable structure; and by a detection structure formed by a second piezoelectric region of a second piezoelectric material, supported by the deformable structure and configured to detect the deformation of the deformable structure.

A lithium niobate semiconductor structure includes: a first lithium niobate material layer, a second lithium niobate material layer and a third lithium niobate material layer. A polarization direction of a ferroelectric domain of the first lithium niobate material layer is a first direction. The second lithium niobate material layer is spaced apart from the first lithium niobate material layer, and a polarization direction of a ferroelectric domain of the second lithium niobate material layer is the first direction. The third lithium niobate material layer is sandwiched between the first lithium niobate material layer and the second lithium niobate material layer, and a polarization direction of a ferroelectric domain of the third lithium niobate material layer is a second direction; the first direction is opposite to the second direction.