Bulk acoustic wave resonator, manufacturing method thereof and filter

A bulk acoustic wave resonator, comprising a dielectric substrate, a first electrode, a piezoelectric layer, and a second electrode;

• wherein the dielectric substrate comprises a first surface and a second surface opposite to each other in a thickness direction of the dielectric substrate, the first electrode is on a side of the first surface away from the second surface, the piezoelectric layer is on a side of the first electrode away from the dielectric substrate, and the second electrode is on a side of the piezoelectric layer away from the first electrode;
• wherein
• the dielectric substrate has a first cavity penetrating through the dielectric substrate in the thickness direction of the dielectric substrate, and the first cavity comprises a first opening penetrating through the first surface, and a second opening penetrating through the second surface;
• the first opening comprises a plurality of first sides sequentially arranged in a clockwise direction, and a plurality of first connecting sides, each of which connects two adjacent first sides;
• the second opening comprises a plurality of second sides sequentially arranged in a clockwise direction, and a plurality of second connecting sides, each of which connects two adjacent second sides;
• the plurality of first sides are in one-to-one correspondence with the plurality of second sides, and the plurality of first connecting sides are in one-to-one correspondence with the plurality of second connecting sides;
• for any two adjacent first sides and the first connecting side connecting the two adjacent first sides, a tangent line at any point on one first side intersects with a tangent line at any point on the other first side at a first intersection point, and the first intersection point is on a side of the first connecting side close to the second connecting side corresponding to the first connecting side;
• and
• for any two adjacent second sides and the second connecting side connecting the two adjacent second sides, a tangent line at any point on one second side intersects with a tangent line at any point on the other second side at a second intersection point, and the second intersection point is on a side of the second connecting side away from the first connecting side corresponding to the second connecting side.