Bulk acoustic resonator and manufacturing method thereof, filter and electronic device

A bulk acoustic resonator, comprising:

• a substrate, an acoustic reflection structure, a bottom electrode, a piezoelectric layer, and a top electrode, wherein
• the acoustic reflection structure is arranged on the substrate or is embedded in the substrate;
• the bottom electrode, the piezoelectric layer and the top electrode are sequentially arranged on a side of a structure formed by the acoustic reflection structure and the substrate, a first depression is defined on a surface of the bottom electrode away from the substrate, the first depression is filled by the piezoelectric layer, a second depression is defined on a surface of the piezoelectric layer away from the substrate, the piezoelectric layer has an equal thickness in a direction perpendicular to a plane where the substrate is located, and an orthographic projection of the first depression on the plane where the substrate is located is configured to cover an orthographic projection of the second depression on the plane where the substrate is located;
• and
• the top electrode comprises a plurality of edges, and in the direction perpendicular to the plane where the substrate is located, the second depression is arranged to correspond to at least one of the edges of the top electrode.