A bulk-acoustic wave resonator includes: a membrane layer disposed on a substrate and forming a cavity; a lower electrode disposed on the membrane layer; a piezoelectric layer disposed on the lower electrode; an upper electrode disposed on the piezoelectric layer, and including a frame part disposed at an edge of an active area and having a thickness greater than that of a portion of the upper electrode disposed in a central portion of the active area; and a frequency adjusting layer disposed on the piezoelectric layer and the upper electrode. The frequency adjusting layer is excluded from an inclined surface of the frame part, or a thickness of a portion of the frequency adjusting layer on the inclined surface is less than that of other portions of the frequency adjusting layer. The frequency adjusting layer is disposed on a portion of the piezoelectric layer protruding from the upper electrode.

Devices and processes for preparing devices are described for a bulk acoustic wave resonator. A stack formed over a substrate includes a piezoelectric film element, a first (e.g., bottom) electrode coupled to a first side of the piezoelectric film element, and a second (e.g., top) electrode that is coupled to a second side of the piezoelectric film element. A cavity is positioned between the stack and the substrate. The resonator includes one or more planarizing layers, including a first planarizing layer around the cavity, wherein a first portion of the first electrode is adjacent the cavity and a second portion of the first electrode is adjacent the first planarizing layer. The resonator optionally includes an air reflector around the perimeter of the piezoelectric film element. The stack is configured to resonate in response to an electrical signal applied between the first electrode and the second electrode.

A method for forming a bulk acoustic wave resonance device is provided, includes: forming a first stack, and said forming the first stack includes providing a first substrate; forming a piezoelectric layer on the first substrate; forming a first electrode layer on the piezoelectric layer; forming a cavity preprocessing layer on the piezoelectric layer, and a cavity is to be formed based on the cavity preprocessing layer, the cavity preprocessing layer at least covers a first end of the first electrode layer, and the cavity preprocessing layer is in contact with the piezoelectric layer, a first side of the first stack corresponds to a side of the first substrate, and a second side of the first stack corresponds to a side of the cavity preprocessing layer; forming a second stack, and said forming the second stack includes providing a second substrate; joining the first stack and the second stack, and the second stack is disposed at the second side; removing the first substrate, and the first side corresponds to a side of the piezoelectric layer; forming a second electrode layer at the first side, and the second electrode layer is in contact with the piezoelectric layer; and removing the second stack.

Disclosed is an acoustic wave resonator comprising a substrate material formed of aluminum nitride (AIN) doped with one or more of zinc (Zn), lithium (Li), silicon (Si), or germanium (Ge) to enhance performance of the acoustic wave resonator.

The present disclosure provides a filter unit and a manufacturing method therefor, and an electronic device, relating to the technical field of radio frequency micro-electromechanical systems. The filter unit includes a resonant structure; and a substrate disposed at one side of the resonant structure, the substrate including a modified structure and a supporting structure surrounding the modified structure, and a cavity being formed between the modified structure and the resonant structure. The filter unit provided in the present disclosure can greatly simplify the process manufacturing flow and reduce the process manufacturing procedure difficulty by forming a cavity between the modified structure and the resonant structure.

An on-chip acoustic delay line (ADL) for operation in the radio frequency (RF) range uses a two-dimensional array of resonant rods and a piezoelectric layer having corrugated structure. The ADL has one or more programmable passband frequencies which are determined by the lithographically-defined artificial dispersive characteristics of acoustic metamaterials formed by forests of the locally resonant rods and selectable attached matching networks. The ADL devices offer exceptionally high fractional bandwidth and low insertion loss. The ADL can be used in self-interference cancellation networks to provide full duplex radio.

A method of manufacturing a bulk acoustic wave filter is provided, including: forming an acoustic reflection air cavity, a sacrificial layer, a seed layer, a lower electrode layer and a piezoelectric layer of n resonators on a substrate in sequence, wherein n is greater than or equal to 2; taking N from 1 to n for respectively repeating following steps: forming an N-th metal hard mask layer, defining an effective area of a first resonator to an N-th resonator by using a photolithography process, removing the N-th metal hard mask layer outside the effective area of the first resonator to the N-th resonator, oxidizing the piezoelectric layer outside the effective area of the first resonator to the N-th resonator to form an N-th oxidized part of the piezoelectric layer, and etching the N-th oxidized part of the piezoelectric layer; removing the metal hard mask layer of the effective area of the first resonator to the N-th resonator, so as to form the piezoelectric layer having different thicknesses of the first resonator to the N-th resonator; and forming an upper electrode layer on the piezoelectric layer having different thicknesses of the first resonator to the N-th resonator.

A method for fabricating a film bulk acoustic resonator (FBAR) structure includes: sequentially forming a top electrode material layer, a piezoelectric layer, and a bottom electrode material layer on a substrate; patterning the bottom electrode material layer to form a bottom electrode; forming a sacrificial layer above the bottom electrode; bonding a bottom cap wafer onto the sacrificial layer; removing the substrate; patterning the top electrode material layer to form a top electrode; and removing a portion of the sacrificial layer to form a lower cavity.

An acoustic resonator device is provided that includes a substrate; a piezoelectric layer having front and back surfaces, with the back surface supported by the substrate; a conductor pattern at the front surface of the piezoelectric layer and including an interdigital transducer (IDT) including a first busbar, a second busbar, and interleaved IDT fingers, with the IDT fingers including a first IDT finger and an nth IDT finger at opposing ends of the IDT; a first grating element that includes a grating bar extending from one of the first busbar or the second busbar, the first grating element being adjacent and parallel to the first IDT finger; a front-side dielectric layer at a front surface of the piezoelectric layer; and a back-side dielectric layer at a back surface of the piezoelectric layer.

A resonator is provided. The resonator includes a substrate, a bottom electrode, a piezoelectric layer and a top electrode. The bottom electrode is arranged between the substrate and the piezoelectric layer, the piezoelectric layer is arranged between the bottom electrode and the top electrode, and a multilayer cavity is arranged between the bottom electrode and the substrate. The multilayer cavity has a width gradually decreased in a direction away from the substrate, so that the change in shapes of the bottom electrode and the piezoelectric layer subsequently arranged on the multilayer cavity at a boundary of each layer of the multilayer cavity is reduced, thus reducing the change in stress due to a large change in shape. A filter, an electronic device and a method for manufacturing a resonator are further provided.