Micromachined ultrasonic transducers integrated with complementary metal oxide semiconductor (CMOS) substrates are described, as well as methods of fabricating such devices. Fabrication may involve two separate wafer bonding steps. Wafer bonding may be used to fabricate sealed cavities in a substrate. Wafer bonding may also be used to bond the substrate to another substrate, such as a CMOS wafer. At least the second wafer bonding may be performed at a low temperature.

A sensor chip includes a first substrate with a first surface and a second surface including at least one CMOS circuit, a first MEMS substrate with a first surface and a second surface on opposing sides of the first MEMS substrate, a second substrate, a second MEMS substrate, and a third substrate including at least one CMOS circuit. The first surface of the first substrate is attached to a packaging substrate and the second surface of the first substrate is attached to the first surface of the first MEMS substrate. The second surface of the first MEMS substrate is attached to the second substrate. The first substrate, the first MEMS substrate, the second substrate and the packaging substrate are provided with electrical inter-connects.

A sensor device may include a base layer, and an ASIC element disposed on the base layer. The ASIC element may include a plurality of electrical contact points. The sensor device may include a MEMS element. The MEMS element may include a plurality of through-silicon vias. The sensor device may include a plurality of conductive contact elements. Each conductive contact element may be disposed between, and electrically coupling, a respective through-silicon via and a respective electrical contact point. The sensor device may include a protective layer disposed between the ASIC element and the MEMS element. The protective layer may be composed of material(s) having a physical property defined to permit the protective layer to mitigate stress forces directed from the ASIC element to the MEMS element, to prevent corrosion, and/or to prevent leakage current between electrical connections due to pollution and/or humidity.

The present disclosure provides a packaging method, including: providing a first semiconductor substrate; forming a bonding region on the first semiconductor substrate, wherein the bonding region of the first semiconductor substrate includes a first bonding metal layer and a second bonding metal layer; providing a second semiconductor substrate having a bonding region, wherein the bonding region of the second semiconductor substrate includes a third bonding layer; and bonding the first semiconductor substrate to the second semiconductor substrate by bringing the bonding region of the first semiconductor substrate in contact with the bonding region of the second semiconductor substrate; wherein the first and third bonding metal layers include copper (Cu), and the second bonding metal layer includes Tin (Sn). An associated packaging structure is also disclosed.

A process for manufacturing electroacoustic modules including: forming an assembly with a redistribution structure and a plurality of dice arranged in a dielectric region; forming a wafer with a semiconductor body and a plurality of respective unit portions laterally staggered, each of which includes a respective supporting region, set in contact with the semiconductor body, and a number of actuators; reducing the thickness of the semiconductor body and then selectively removing portions of the semiconductor body so as to singulate, starting from the wafer, a plurality of transduction structures, each including a semiconductor substrate, which contacts a corresponding supporting region and is traversed by cavities delimited by portions of the supporting region that form membranes mechanically coupled to the actuators; and then coupling the transduction structures to the redistribution structure of the assembly.

An ultrasonic transducer includes a membrane, a bottom electrode, and a plurality of cavities disposed between the membrane and the bottom electrode, each of the plurality of cavities corresponding to an individual transducer cell. Portions of the bottom electrode corresponding to each individual transducer cell are electrically isolated from one another. Each portion of the bottom electrode corresponds to each individual transducer that cell further includes a first bottom electrode portion and a second bottom electrode portion, the first and second bottom electrode portions electrically isolated from one another.

A method for forming a hybrid-bonding structure is provided. The method includes forming a first dielectric layer over a first semiconductor substrate. The first semiconductor substrate includes a conductive structure. The method also includes partially removing the first dielectric layer to form a first dielectric dummy pattern, a second dielectric dummy pattern and a third dielectric dummy pattern and an opening through the first dielectric layer. The first dielectric dummy pattern, the second dielectric dummy pattern and the third dielectric dummy pattern are surrounded by the opening. In addition, the method includes forming a first conductive line in the opening. The first conductive line is in contact with the conductive structure.

The present disclosure relates to a method for transferring a target layer to a substrate. The method includes providing a stack by forming a first transfer layer over a first substrate, forming a second transfer layer on the first transfer layer, the second transfer layer being water-soluble, and forming the target layer on the second transfer layer, such that the stack has a top surface. The method also includes bonding the top surface of the stack to a second substrate, separating the first transfer layer from the second transfer layer, and dissolving the second transfer layer in water.

A stacked semiconductor structure includes a first substrate. A multilayer interconnect is disposed over the first substrate. Metal sections are disposed over the multilayer interconnect. First bonding features are over the metal sections. A second substrate has a front surface. A cavity extends from the front surface into a depth D in the second substrate. A movable structure is disposed over the front surface of the second substrate and suspending over the cavity. The movable structure includes a dielectric membrane, metal units over the dielectric membrane and a cap dielectric layer over the metal units. Second bonding features are over the cap dielectric layer and bonded to the first bonding features. The second bonding features extend through the cap dielectric layer and electrically coupled to the metal units.

Aspects of the technology described herein relate to ultrasound transducer devices including capacitive micromachined ultrasonic transducers (CMUTs) and methods for forming CMUTs in ultrasound transducer devices. Some embodiments include forming a cavity of a CMUT by forming a first layer of insulating material on a first substrate, forming a second layer of insulating material on the first layer of insulating material, and then etching a cavity in the second insulating material. A second substrate may be bonded to the first substrate to seal the cavity. The first layer of insulating material may include, for example, aluminum oxide. The first substrate may include integrated circuitry. Some embodiments include forming through-silicon vias (TSVs) in the first substrate prior to forming the first and second insulating layers (TSV-Middle process) or subsequent to bonding the first and second substrates (TSV-Last process).