Bulk acoustic wave resonance device and bulk acoustic wave filter

A bulk acoustic wave resonance device, comprising:

• a first layer comprising a cavity disposed at a first side of the first layer;
• a first electrode layer disposed in the cavity;
• a second layer disposed at the first side and disposed on the first electrode layer, wherein the second layer is a flat layer and covers the first cavity;
• and
• a second electrode layer disposed at the first side and disposed on the second layer,
• wherein the first electrode layer comprises at least two first electrode bars or the second electrode layer comprises at least two second electrode bars;
• wherein the second layer comprises a piezoelectric layer comprising a plurality of crystal grains, the plurality of crystal grains comprising a first crystal grain and a second crystal grain, and the first crystal grain and the second crystal grain are any two crystal grains of the plurality of crystal grains, wherein a first coordinate axis along a first direction corresponds to a height of the first crystal grain, a second coordinate axis along a second direction corresponds to a height of the second crystal grain, and the first direction is the same as or opposite to the second direction;
• wherein the first electrode layer and the second electrode layer are adapted to excite a bulk acoustic wave propagating in a direction perpendicular to the piezoelectric layer, and the bulk acoustic wave propagating in the direction perpendicular to the piezoelectric layer comprises a shear vertical wave or a longitudinal wave;
• wherein an overlap portion of the second electrode layer overlapping with the first electrode layer is disposed above the cavity, and a projection of the overlap portion along a direction perpendicular to the first layer falls within the cavity so as to prevent the bulk acoustic wave propagating from a resonance region to the first layer.