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.

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.

The present disclosure relates to a method for fabricating a laterally excited shear mode acoustic resonator. The method includes: providing a piezoelectric layer including monocrystalline lithium niobate and/or monocrystalline lithium tantalate; forming an acoustic mirror on a first surface of the piezoelectric layer; the acoustic mirror including at least one first acoustic reflection layer and at least one second acoustic reflection layer, the first acoustic reflection layers and the second acoustic reflection layers being alternately superimposed, and acoustic impedance of each of the first acoustic reflection layers being less than that of each of the second acoustic reflection layers; bonding a bearing wafer on a first surface of the acoustic mirror; and forming an electrode unit and a lateral reflector on a second surface of the piezoelectric layer.

The present disclosure relates to a method for fabricating a laterally excited shear mode acoustic resonator. The method includes: providing a piezoelectric layer including monocrystalline lithium niobate and/or monocrystalline lithium tantalate; forming an acoustic mirror on a first surface of the piezoelectric layer; the acoustic mirror including at least one first acoustic reflection layer and at least one second acoustic reflection layer, the first acoustic reflection layers and the second acoustic reflection layers being alternately superimposed, and acoustic impedance of each of the first acoustic reflection layers being less than that of each of the second acoustic reflection layers; bonding a bearing wafer on a first surface of the acoustic mirror; and forming an electrode unit and a lateral reflector on a second surface of the piezoelectric layer.

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.

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.

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.

Modern RF front end filters feature acoustic resonators in a film bulk acoustic resonator (FBAR) structure. An acoustic filter is a circuit that includes at least (and typically significantly more) two resonators. The acoustic resonator structure comprises a substrate including sidewalls and a vertical cavity between the sidewalls and two or more resonators deposited in the vertical cavity.