A method of manufacturing an electronic device formed in a cavity may include, on a first substrate having a bottom surface and a top surface, forming a first side wall of a certain height along a periphery on the bottom surface to surround an electronic circuit disposed on the bottom surface; forming a via communicating between the bottom surface and the top surface, forming of the via including stacking a first stop layer and a second stop layer sequentially on a portion of the bottom surface of the first substrate corresponding to the via and etching the first substrate to form a through-hole corresponding to the via, a rate of etching the first substrate being greater than that of the first stop layer and a rate of etching the first stop layer being greater than that of the second stop layer; forming a second side wall of a certain height along a periphery on a top surface of the second substrate; and aligning and bonding the first side wall and the second side wall.

Methods of manufacturing an electronic device formed in a cavity may include providing a first substrate having a first side wall including a first metal formed along a periphery on a bottom surface thereof and surrounding an electronic circuit disposed on the bottom surface, providing a second substrate having a second side wall including a second metal and a third metal formed along a periphery on a top surface thereof, aligning the first substrate with the second substrate with the first side wall opposing and contacting the second side wall to internally define a cavity between the bottom surface of the first substrate, the top surface of the second substrate, the first side wall ,and the second side wall, and heating and bonding the first substrate and the second substrate by transient liquid phase bonding.

Methods of preventing water from penetrating inside a pair of bonded wafers that are bonded to one another during manufacture of an electronic device. A method is provided for manufacturing an electronic device including a first substrate having a first side wall of a certain height formed along a periphery to surround an electronic circuit disposed on a bottom surface and a second substrate having a second side wall of a certain height formed along a periphery on a top surface, the second side wall being aligned and bonded with the first side wall. The method includes forming the first side wall on a bottom surface of a first wafer as the bottom surface of the first substrate and forming a first sealing portion of a certain height along a periphery; forming the second side wall on a top surface of a second wafer as the top surface of the second substrate and forming a second sealing portion of a certain height along a periphery; and aligning and bonding the first wafer and the second wafer with each other, the first sealing portion and the first side wall being bonded with the second sealing portion and the second side wall respectively by transient liquid phase bonding.

An electronic device, such as a filter, includes a first substrate having a bottom surface and a top surface, a first side wall of a certain height being formed along a periphery of the bottom surface to surround an electronic circuit disposed on the bottom surface, an external electrode formed on the top surface, the external electrode being connected to the electronic circuit by a via communicating with the bottom surface and a second substrate. The second substrate has a second side wall of a certain height formed along a periphery of a top surface, the second side wall being aligned and bonded with the first side wall to internally form a cavity defined between the bottom surface of the first substrate, the top surface of the second substrate, the first side wall, and the second side wall.

A device including a piezoelectric substrate, an interdigital transducer (IDT), and an antireflective structure is disclosed herein. The piezoelectric substrate has a front-side surface and a smoothed back-side surface. The IDT is on the front-side surface of the piezoelectric substrate. The antireflective structure is over at least a portion of the smoothed back-side surface of the piezoelectric substrate. By having the antireflective structure on at least a portion of the smoothed back-side surface of the piezoelectric substrate, reflection of spurious bulk acoustic waves toward the front-side surface of the piezoelectric substrate can be reduced and/or eliminated to lessen interference with surface acoustic waves. The reduction and/or elimination of spurious bulk acoustic waves allows the device to forego conventional roughening of the back-side surface of the piezoelectric substrate, thereby reducing fractures at the back-side surface and allowing for singulation techniques capable of producing smaller die sizes.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. A first patterned electrode is deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the first electrode and a planarized support layer is deposited over the sacrificial layer, which is then bonded to a substrate wafer. The crystalline substrate is removed and a second patterned electrode is deposited over a second surface of the film. The sacrificial layer is etched to release the air reflection cavity. Also, a cavity can instead be etched into the support layer prior to bonding with the substrate wafer. Alternatively, a reflector structure can be deposited on the first electrode, replacing the cavity.

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. A first patterned electrode is deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the first electrode and a planarized support layer is deposited over the sacrificial layer, which is then bonded to a substrate wafer. The crystalline substrate is removed and a second patterned electrode is deposited over a second surface of the film. The sacrificial layer is etched to release the air reflection cavity. Also, a cavity can instead be etched into the support layer prior to bonding with the substrate wafer. Alternatively, a reflector structure can be deposited on the first electrode, replacing the cavity.

A production method for a composite substrate according to the present invention comprises (a) a step of mirror-polishing a piezoelectric-substrate side of a laminated substrate formed by bonding a piezoelectric substrate and a support substrate; (b) a step of performing machining using an ion beam or a neutral atom beam so that a thickness of an outer peripheral portion of the piezoelectric substrate is larger than a thickness of an inner peripheral portion and a difference between a largest thickness and a smallest thickness of the inner peripheral portion of the piezoelectric substrate is 100 nm or less over an entire surface; and (c) a step of flattening the entire surface of the piezoelectric substrate to remove at least a part of an altered layer formed by the machining using the ion beam or the neutral atom beam in the step (b).

A composite substrate production method of the invention includes (a) a step of mirror polishing a substrate stack having a diameter of 4 inch or more, the substrate stack including a piezoelectric substrate and a support substrate bonded to each other, the mirror polishing being performed on the piezoelectric substrate side until the thickness of the piezoelectric substrate reaches 3 m or less; (b) a step of creating data of the distribution of the thickness of the mirror-polished piezoelectric substrate; and (c) a step of performing machining with an ion beam machine based on the data of the thickness distribution so as to produce a composite substrate have some special technical features.