Acoustic resonator and method of manufacturing the same

A method to manufacture an acoustic resonator, comprising:

• forming a resonant part comprising a central portion and an extension portion extended outwardly of the central portion,
• wherein the forming the resonant part comprises:
• forming a first electrode on a substrate;
• forming an insertion layer on the first electrode and the substrate;
• forming a piezoelectric layer comprising a piezoelectric portion stacked on the first electrode and a bent portion extended at an incline from a boundary of the piezoelectric portion;
• and
• forming a second electrode on the piezoelectric layer,
• wherein the insertion layer is disposed over the resonant part to surround and expose the central portion, and
• wherein an end of the second electrode is disposed on the incline.

An acoustic resonator, comprising:

• a resonant part comprising:
• a central portion;
• an extension portion extended outwardly of the central portion;
• a first electrode, a piezoelectric layer, and a second electrode stacked on a substrate, in the central portion;
• and
• an insertion layer disposed below the piezoelectric layer in the extension portion,
• wherein a portion of the piezoelectric layer disposed in the extension portion comprises an inclined portion caused by the insertion layer,
• wherein the insertion layer is disposed over the resonant part to surround and expose the central portion, and
• wherein an end of the second electrode is disposed on the incline.

An acoustic resonator, comprising:

• a resonant part comprising:
• a central portion;
• an extension portion extended outwardly of the central portion;
• a first electrode, a piezoelectric layer, and a second electrode stacked on a substrate, in the central portion;
• and
• an insertion layer disposed an insertion layer disposed on the first electrode in the extension portion,
• wherein the piezoelectric layer comprises
• a piezoelectric portion disposed in the central portion, and
• a bent portion disposed in the extension portion and extended from the piezoelectric portion at an incline depending on a shape of the insertion layer,
• wherein the insertion layer is disposed at the extension portion disposed at both ends of the central portion in a cross-sectional surface where the resonant part is cut across the center portion, and
• wherein an end of the second electrode is disposed on the incline.