Method of manufacturing bulk acoustic wave resonator

A method of manufacturing a bulk acoustic wave resonator, comprising:

• providing a first substrate and a piezoelectric substrate;
• bonding the piezoelectric substrate to the first substrate through a bonding layer;
• performing a thinning process on the piezoelectric substrate to form a piezoelectric layer having a desired thickness, thereby forming a piezoelectric substrate structure comprising the piezoelectric layer and the first substrate bonded to each other;
• forming a first electrode structure on the piezoelectric layer of the piezoelectric substrate structure, the first electrode structure is located on a first side of the piezoelectric layer away from the first substrate;
• forming a dielectric layer on the first electrode structure, and performing a patterning process on the dielectric layer to form a patterned dielectric layer comprising a sacrificial dielectric part and a periphery dielectric part separated from each other;
• forming a boundary layer on the patterned dielectric layer, the boundary layer covers a surface of the patterned dielectric layer and surrounds the sacrificial dielectric part;
• removing the first substrate and the bonding layer from the piezoelectric layer with the first electrode structure, the patterned dielectric layer, and the boundary layer, so as to expose a second side of the piezoelectric layer, the second side is opposite to the first side;
• forming a second electrode structure on the second side of the piezoelectric layer;
• and
• removing the sacrificial dielectric part to form a resonant cavity between the boundary layer and the piezoelectric layer and between the boundary layer and the first electrode structure.