We describe here a method that employs through substrate vias (TSVs) to frustrate the standing waves that are formed in the metal trace. TSVs may be formed at intervals in the first substrate, electrically coupling the metal bondline to the ground plane.

A micro-resonator employs a lid-integrated electrode to one or more of drive, sense and tune a vibrational resonant mode of a microelectromechanical systems (MEMS) resonator. The micro-resonator includes a lid attached to a base that provides a resonator cavity. The micro-resonator further includes the MEMS resonator extending from a surface of the base toward the lid within the resonator cavity. The lid-integrated electrode extends vertically from the lid into the resonator cavity toward the base. The vertically extending, lid-integrated electrode is positioned spaced from and adjacent to a side of the MEMS resonator to one or more of drive, sense and tune mechanical movement of the MEMS resonator.

A method for fabricating an integrated MEMS-CMOS device uses a micro-fabrication process that realizes moving mechanical structures (MEMS) on top of a conventional CMOS structure by bonding a mechanical structural wafer on top of the CMOS and etching the mechanical layer using plasma etching processes, such as Deep Reactive Ion Etching (DRIE). During etching of the mechanical layer, CMOS devices that are directly connected to the mechanical layer are exposed to plasma. This sometimes causes permanent damage to CMOS circuits and is termed Plasma Induced Damage (PID). Embodiments of the present invention presents methods and structures to prevent or reduce this PID and protect the underlying CMOS circuits by grounding and providing an alternate path for the CMOS circuits until the MEMS layer is completely etched.

A microstructure may be provided by forming a metal layer such as a molybdenum layer over a substrate. An aluminum nitride layer is formed on a top surface of the metal layer. A surface portion of the aluminum nitride layer is converted into a continuous aluminum oxide-containing layer by oxidation. A dielectric spacer layer may be formed over the continuous aluminum oxide-containing layer. Contact via cavities extending through the dielectric spacer layer, the continuous aluminum oxide containing layer, and the aluminum nitride layer and down to a respective portion of the at least one metal layer may be formed using etch processes that contain a wet etch step while suppressing formation of an undercut in the aluminum nitride layer. Contact via structures may be formed in the contact via cavities. The microstructure may include a micro-electromechanical system (MEMS) device containing a piezoelectric transducer.

A microstructure may be provided by forming a metal layer such as a molybdenum layer over a substrate. An aluminum nitride layer is formed on a top surface of the metal layer. A surface portion of the aluminum nitride layer is converted into a continuous aluminum oxide-containing layer by oxidation. A dielectric spacer layer may be formed over the continuous aluminum oxide-containing layer. Contact via cavities extending through the dielectric spacer layer, the continuous aluminum oxide containing layer, and the aluminum nitride layer and down to a respective portion of the at least one metal layer may be formed using etch processes that contain a wet etch step while suppressing formation of an undercut in the aluminum nitride layer. Contact via structures may be formed in the contact via cavities. The microstructure may include a micro-electromechanical system (MEMS) device containing a piezoelectric transducer.

A conductive layer is deposited into a trench in a sacrificial layer on a substrate. An etch stop layer is deposited over the conductive layer. The sacrificial layer is removed to form a gap. In one embodiment, a beam is over a substrate. An interconnect is on the beam. An etch stop layer is over the beam. A gap is between the beam and the etch stop layer.

A silicon-on-sapphire chip with minimal thermal strain preload is provided. The chip includes a sapphire substrate having a first-sapphire surface and an opposing second-sapphire surface; and a silicon layer overlaying the first-sapphire surface. The silicon layer is formed by: creating a plurality of buried cavities in a plane within tens of microns from a first-silicon surface of a silicon wafer; laser fusing the first-silicon surface to the first-sapphire surface at room temperature to attach the silicon wafer to a sapphire wafer; and cleaving the silicon wafer along the plane including the plurality of buried cavities. A silicon-wafer layer is formed from the silicon material between the first-silicon surface and the plane of the plurality of buried cavities. The silicon-wafer layer and the sapphire wafer form a silicon-on-sapphire wafer. The silicon-on-sapphire chip is formed by dicing the silicon-on-sapphire wafer.

A MEMS device is disclosed. The MEMS device includes a first substrate. At least one structure is formed within the first substrate. The first substrate includes at least one first conductive pad thereon. The MEMS device also includes a second substrate. The second substrate includes a passivation layer. The passivation layer includes a plurality of layers. A top layer of the plurality of layers comprises an outgassing barrier layer. At least one second conductive pad and at least one electrode are coupled to the top layer. At least one first conductive pad is coupled to the at least one second conductive pad.

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.

A method of bonding of germanium to aluminum between two substrates to create a robust electrical and mechanical contact is disclosed. An aluminum-germanium bond has the following unique combination of attributes: (1) it can form a hermetic seal; (2) it can be used to create an electrically conductive path between two substrates; (3) it can be patterned so that this conduction path is localized; (4) the bond can be made with the aluminum that is available as standard foundry CMOS process. This has the significant advantage of allowing for wafer-level bonding or packaging without the addition of any additional process layers to the CMOS wafer.