Disclosed is a film bulk acoustic resonator (FBAR) type filter including a substrate including two or more cavities on a top surface thereof, a lower electrode formed above the substrate, a piezoelectric layer formed above the lower electrode, two or more upper electrodes formed above the piezoelectric layer, and a package layer including a wall vertically extending while surrounding a periphery of certain areas in which the cavities and the lower electrode are formed and a roof disposed above the wall while being spaced apart from the upper electrodes to seal the certain areas.

Aspects of this disclosure relate to bulk acoustic wave resonators. A bulk acoustic wave resonator includes a patterned mass loading layer that affects a resonant frequency of the bulk acoustic wave resonator. The patterned mass loading layer can have a duty factor in a range from 0.2 to 0.8 in a main acoustically active region of the bulk acoustic wave resonator. Related filters, acoustic wave dies, radio frequency modules, wireless communications devices, and methods are disclosed.

A method of manufacture for an acoustic resonator or filter device. In an example, the present method can include forming metal electrodes with different geometric areas and profile shapes coupled to a piezoelectric layer overlying a substrate. These metal electrodes can also be formed within cavities of the piezoelectric layer or the substrate with varying geometric areas. Combined with specific dimensional ratios and ion implantations, such techniques can increase device performance metrics. In an example, the present method can include forming various types of perimeter structures surrounding the metal electrodes, which can be on top or bottom of the piezoelectric layer. These perimeter structures can use various combinations of modifications to shape, material, and continuity. These perimeter structures can also be combined with sandbar structures, piezoelectric layer cavities, the geometric variations previously discussed to improve device performance metrics.

A laterally excited bulk acoustic wave device is disclosed. The laterally excited bulk acoustic wave device can include a first solid acoustic mirror, a second solid acoustic mirror, a piezoelectric layer that is positioned between the first solid acoustic mirror and the second solid acoustic mirror, an interdigital transducer electrode on the piezoelectric layer, and a support substrate arranged to dissipate heat associated with the bulk acoustic wave. The interdigital transducer electrode is arranged to laterally excite a bulk acoustic wave. The first solid acoustic mirror and the second solid acoustic mirror are arranged to confine acoustic energy of the bulk acoustic wave. The first solid acoustic mirror is positioned on the support substrate.

Acoustic resonators and filter devices. An acoustic resonator includes a substrate having a surface and a single-crystal piezoelectric plate having front and back surfaces. The back surface is attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. A conductor pattern formed is formed on the front surface of the piezoelectric plate, including an interdigital transducer (IDT) with interleaved fingers of the IDT on the diaphragm. The substrate and the piezoelectric plate are the same material.

A radio frequency filter includes at least a first sub-filter and a second sub-filter connected in parallel between a first port and a second port. Each of the sub-filters has a piezoelectric plate having front and back surfaces, the back surface attached to a substrate, and portions of the piezoelectric plate forming diaphragms spanning respective cavities in the substrate. A conductor pattern is formed on the front surface of the plate, the conductor pattern includes interdigital transducers (IDTs) of a respective plurality of resonators, with interleaved fingers of each IDT disposed on a respective diaphragm of the plurality of diaphragms. A thickness of the portions of the piezoelectric plate of the first sub-filter is different from a thickness of the portions of the piezoelectric plate of the second sub-filter.

The invention provides a planarization method, which can make the local flatness of the product to be processed more uniform. The product has a cavity filled with oxide and includes a first electrode layer, a piezoelectric layer and a second electrode layer superposed on the cavity. The first electrode layer covers the cavity and includes a first inclined face around the first electrode layer, and the piezoelectric layer covers the first electrode layer and is arranged on the first electrode layer. The planarization method includes: depositing a passivation layer on the second electrode layer and etching the passivation layer completely until the thickness of the passivation layer is reduced to the required thickness.

Filter devices and fabrication methods are disclosed. A filter device includes a piezoelectric plate and a conductor pattern on a front surface of the piezoelectric plate. The conductor pattern includes interdigital transducers (IDTs) of a plurality of transversely-excited film bulk acoustic resonators (XBARs) and a plurality of conductors connecting the plurality of XBARs in a ladder filter circuit architecture. The plurality of conductors includes a first conductor adjacent to a second conductor. An opening is provided through the piezoelectric plate between the first conductor and the second conductor.

Disclosed are a resonator and a manufacturing method thereof, a filter, and an electronic device. The resonator includes a substrate, a Bragg reflection layer, and a piezoelectric layer that are sequentially stacked. A first electrode is disposed on a surface that is of the piezoelectric layer and that faces the Bragg reflection layer, a second electrode is disposed on a surface that is of the piezoelectric layer and that is away from the Bragg reflection layer, a border ring is disposed on a surface that is of the second electrode and that is away from the piezoelectric layer, and the resonator has a first resonance region and a second resonance region corresponding to the border ring.

A resonator and a preparation method of a resonator, and a filter relate to the technical field of resonators. The preparation method includes: forming a piezoelectric layer, a first electrode layer, and a first bonding layer on a first substrate; patterning the first bonding layer to form a first bonding ring, a second bonding ring, and a third bonding ring, and etching an exposed part of the first electrode layer to form a first window; forming a first supporting layer and a second bonding layer on the second substrate; patterning the second bonding layer to form a fourth bonding ring and a fifth bonding ring, and etching an exposed part of the first supporting layer to form a second window and a third window to obtain a boundary ring located between the third window and the second window; bonding the third bonding ring and the fifth bonding ring, and bonding the second bonding ring and the fourth bonding ring to obtain a cavity structure of the resonator; and removing the first substrate, and forming a second electrode layer on the piezoelectric layer. According to the preparation method, preparation of the boundary ring is realized through a packaging and bonding process, and the preparation process of a resonator is simple.