Skyworks Global Pte. Ltd.

A system for compensating for thermal stress in piezoelectric microelectromechanical systems devices can have a piezoelectric layer at least partially spanning a cavity such that it generates electrical signals when external forces cause the piezoelectric layer to vibrate with respect to the cavity. At least one electrode layer can include a conductive metal positioned adjacent the piezoelectric layer and configured as an electrode to accept the electrical signals. The piezoelectric layer and electrode layer can have an expected thermal stress tending to cause expected deflection even when external forces are not causing the piezoelectric layer to vibrate. A compensation layer can be positioned adjacent at least one of the piezoelectric layer and the at least one electrode layer and configured to counteract the expected deflection from the expected thermal stress.

An acoustic sensor (e.g., for use in a piezoelectric MEMS microphone) includes a substrate and a cantilever beam attached to the substrate. The cantilever beam has a proximal portion attached to the substrate and a distal portion that extends from the proximal portion to a free end of the beam, the beam extending in a first direction between the proximal portion and the free end, the distal portion of the beam having a corrugated section including one or more grooves that extend generally in the first direction. The corrugated section inhibits bending of the corrugated section along the length of the distal portion when the acoustic sensor is subjected to sound pressure. An electrode is disposed on or in the proximal portion of the beam.

A piezoelectric microelectromechanical system microphone comprises a support substrate, a diaphragm including a piezoelectric material attached to the support substrate and configured to deform and generate an electrical potential responsive to impingement of sound waves on the diaphragm, and a compliant anchor formed of a material with a greater compliance than a compliance of the piezoelectric material, the compliant anchor defined in the diaphragm in an anchor region between the piezoelectric material of the diaphragm and the support substrate to improve sensitivity and reduce residual stress impact of the piezoelectric microelectromechanical system microphone.

A piezoelectric microelectromechanical systems device can include a cavity bounded by walls and an asymmetrical bimorph structure at least partially spanning the cavity that includes at least a piezoelectric layer and two electrode layers. The electrode layers can have relative thicknesses configured to compensate for expected temperature stress in the bimorph structure. Thus, metals having different thicknesses can be positioned and configured to compensate deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer and a substrate. A method for making the piezoelectric microelectromechanical systems device is also provided.

A piezoelectric microelectromechanical systems diaphragm microphone can be mounted on a printed circuit board. The microphone can include a substrate with an opening between a bottom end of the substrate and a top end of the substrate. The microphone can have two or more piezoelectric film layers disposed over the top end of the substrate and defining a diaphragm structure. Each of the two or more piezoelectric film layers can have a predefined residual stress that substantially cancel each other out so that the diaphragm structure is substantially flat with substantially zero residual stress. The microphone can include one or more electrodes disposed over the diaphragm structure. The diaphragm structure is configured to deflect when the diaphragm is subjected to sound pressure via the opening in the substrate.

A method of making an acoustic sensor includes forming or providing a mold having one or more grooves extending in a direction of the length of the mold to a distal end of the mold. The method also includes forming or depositing a structure having one or more piezoelectric layers over the top surface of the mold to define a beam with a proximal portion and a distal portion, the distal portion having a corrugated section including one or more grooves that correspond to the one or more grooves of the mold. The method also includes forming or applying an electrode to the proximal portion of the structure and releasing the structure from the mold to form one or more cantilever beams. The corrugated section inhibits bending of the corrugated section along the length of the distal portion of the structure when the acoustic sensor is subjected to sound pressure.

A method of making an acoustic sensor (e.g., for use in a piezoelectric MEMS microphone) includes forming or providing a mold having one or more grooves in a top surface of the mold that extend in a direction of the length of the mold to a distal end of the mold. The method also includes forming or depositing a structure having one or more piezoelectric layers over the top surface of the mold to define a beam, the distal portion of the beam having a corrugated section including one or more grooves that correspond to the grooves of the mold. The method also includes forming a gap in the structure to define two beams separated by the gap, and releasing the structure from the mold to form one or more cantilever beams that increases an acoustic resistance of the gap between sensors.

A method of making an acoustic sensor (e.g., for use in a piezoelectric MEMS microphone) includes forming or providing a mold having one or more grooves in a top surface of the mold that extend in a direction of the length of the mold to a distal end of the mold. The method also includes forming or depositing a structure having one or more piezoelectric layers over the top surface of the mold to define a beam, the distal portion of the beam having a corrugated section including one or more grooves that correspond to the grooves of the mold. The method also includes forming a gap in the structure to define two beams separated by the gap, and releasing the structure from the mold to form one or more cantilever beams that increases an acoustic resistance of the gap between sensors.

A piezoelectric microelectromechanical system microphone comprises a support substrate, a piezoelectric element configured to deform and generate an electrical potential responsive to impingement of sound waves on the piezoelectric element, the piezoelectric element attached to the support substrate about a perimeter of the piezoelectric element, a sensing electrode disposed on the piezoelectric element and configured to sense the electrical potential, and corrugations defined in the piezoelectric element about the perimeter of the piezoelectric element to release residual stress and improve sensitivity of the piezoelectric microelectromechanical system microphone.

An acoustic sensor (e.g., for use in a piezoelectric MEMS microphone) includes a substrate and a cantilever beam attached to the substrate. The cantilever beam has a proximal portion attached to the substrate and a distal portion that extends from the proximal portion to a free end of the beam, the beam extending generally linearly from the proximal portion toward the free end in a first direction. The beam has a wall portion at or proximate the free end that extends in a second direction generally transverse to the first direction and increases an acoustic resistance of the gap between sensors. An electrode is disposed on or in the proximal portion of the beam.