CMOS Ultrasonic Transducers and processes for making such devices are described. The processes may include forming cavities on a first wafer and bonding the first wafer to a second wafer. The second wafer may be processed to form a membrane for the cavities. Electrical access to the cavities may be provided.

An example of a cavity structure comprises a cavity substrate comprising a substrate surface, a cavity extending into the cavity substrate, the cavity having a cavity bottom and cavity walls, and a cap disposed on a side of the cavity opposite the cavity bottom. The cavity substrate, the cap, and the one or more cavity walls form a cavity enclosing a volume. A component can be disposed in the cavity and can extend above the substrate surface. The component can be a piezoelectric or a MEMS device. The cap can have a tophat configuration. The cavity structure can be micro-transfer printed from a source wafer to a destination substrate.

A micro-electromechanical system (MEMS) device includes a moveable element within a cavity. The MEMS device also includes a first layer over the cavity, the first layer having a first hole and a second hole. The first hole has a first diameter. The second hole has a second diameter. The second diameter is larger than the first diameter, and the second hole is farther from the moveable element than the first hole. The first hole is sealed with a first dielectric material. The second hole is sealed with a second dielectric material. The cavity filled with a gas at a pressure of at least approximately 10 torr.

A hollow package (103) includes a substrate (109), an element (111), a partition wall (113), and a top plate (115) and has one or more closed hollow parts (117) that are covered by the substrate (109), the partition wall (113), and the top plate (115), and the substrate (109), the partition wall (113), and the top plate (115) are sealed with a cured product of a sealing resin composition. The top plate (115) and the partition wall (113) are composed of an organic material, and the thickness of the top plate (115), the thickness of the partition wall (113), the width of the partition wall, and the maximum width of the hollow part (117) are each within respective predetermined ranges. The sealing resin composition comprises (A) an epoxy resin that includes one or more selected from the group consisting of an epoxy resin containing two epoxy groups in the molecule and an epoxy resin containing three or more epoxy resins in the molecule and (B) an inorganic filler.

A low-profile packaging structure for a microelectromechanical-system (MEMS) resonator system includes an electrical lead having internal and external electrical contact surfaces at respective first and second heights within a cross-sectional profile of the packaging structure and a die-mounting surface at an intermediate height between the first and second heights. A resonator-control chip is mounted to the die-mounting surface of the electrical lead such that at least a portion of the resonator-control chip is disposed between the first and second heights and wire-bonded to the internal electrical contact surface of the electrical lead. A MEMS resonator chip is mounted to the resonator-control chip in a stacked die configuration and the MEMS resonator chip, resonator-control chip and internal electrical contact and die-mounting surfaces of the electrical lead are enclosed within a package enclosure that exposes the external electrical contact surface of the electrical lead at an external surface of the packaging structure.

An example of a cavity structure comprises a cavity substrate comprising a substrate surface, a cavity extending into the cavity substrate, the cavity having a cavity bottom and cavity walls, and a cap disposed on a side of the cavity opposite the cavity bottom. The cavity substrate, the cap, and the one or more cavity walls form a cavity enclosing a volume. A component can be disposed in the cavity and can extend above the substrate surface. The component can be a piezoelectric or a MEMS device. The cap can have a tophat configuration. The cavity structure can be micro-transfer printed from a source wafer to a destination substrate.

An example of a cavity structure comprises a cavity substrate comprising a substrate surface, a cavity extending into the cavity substrate, the cavity having a cavity bottom and cavity walls, and a cap disposed on a side of the cavity opposite the cavity bottom. The cavity substrate, the cap, and the one or more cavity walls form a cavity enclosing a volume. A component can be disposed in the cavity and can extend above the substrate surface. The component can be a piezoelectric or a MEMS device. The cap can have a tophat configuration. The cavity structure can be micro-transfer printed from a source wafer to a destination substrate.

A low-profile packaging structure for a microelectromechanical-system (MEMS) resonator system includes an electrical lead having internal and external electrical contact surfaces at respective first and second heights within a cross-sectional profile of the packaging structure and a die-mounting surface at an intermediate height between the first and second heights. A resonator-control chip is mounted to the die-mounting surface of the electrical lead such that at least a portion of the resonator-control chip is disposed between the first and second heights and wire-bonded to the internal electrical contact surface of the electrical lead. A MEMS resonator chip is mounted to the resonator-control chip in a stacked die configuration and the MEMS resonator chip, resonator-control chip and internal electrical contact and die-mounting surfaces of the electrical lead are enclosed within a package enclosure that exposes the external electrical contact surface of the electrical lead at an external surface of the packaging structure.

The method comprises fabricating a semiconductor panel comprising a plurality of semiconductor devices, fabricating a cap panel comprising a plurality of caps, bonding the cap panel onto the semiconductor panel so that each one of the caps covers one or more of the semiconductor devices, and singulating the bonded panels into a plurality of semiconductor modules.

An example of a cavity structure comprises a cavity substrate comprising a substrate surface, a cavity extending into the cavity substrate, the cavity having a cavity bottom and cavity walls, and a cap disposed on a side of the cavity opposite the cavity bottom. The cavity substrate, the cap, and the one or more cavity walls form a cavity enclosing a volume. A component can be disposed in the cavity and can extend above the substrate surface. The component can be a piezoelectric or a MEMS device. The cap can have a tophat configuration. The cavity structure can be micro-transfer printed from a source wafer to a destination substrate.