Acoustic wave device with enhanced quality factor and fabrication method thereof

An acoustic wave device comprising:

• a first substrate comprising:
• a first surface;
• a first bulkplate;
• a first electrode, a piezoelectric layer, and a second electrode, wherein the first electrode, the piezoelectric layer, and the second electrode are stacked in sequence, and the first electrode is exposed from the first surface;
• and
• a first frame disposed in the first bulkplate and at least partially surrounding the first electrode;
• and
• a second substrate comprising:
• a second surface;
• a second bulkplate;
• and
• a recess disposed in the second bulkplate and recessed from the second surface;
• wherein the first surface of the first substrate and the second surface of the second substrate are bonded together;
• wherein the recess, the first electrode, the piezoelectric layer, and the second electrode at least partially overlap when viewed along a vertical direction;
• and
• wherein the first substrate and the second substrate form a sealed cavity at the recess.

A method of fabricating an acoustic wave device, the method comprising:

• providing a first bulkplate;
• forming a first electrode on the first bulkplate;
• forming a first frame on the first bulkplate, wherein the first frame at least partially surrounds the first electrode and is separated from the first electrode;
• forming a piezoelectric layer at least on the first electrode;
• forming a second electrode at least on the piezoelectric layer;
• forming a contact hole penetrating the piezoelectric layer;
• forming a first contact in the contact hole, the first contact being electrically connected to the first electrode;
• forming a passivation layer to at least cover the second electrode, so as to form a first substrate;
• applying an adhesion layer to a first side of the first substrate;
• attaching the first substrate to a carrier via the adhesion layer;
• performing a planarization process from a second side of the first substrate to reduce a thickness of the first substrate to a first surface, such that the first electrode is exposed from the first surface;
• providing a second substrate, the second substrate comprising a second bulkplate and a recess, the recess being recessed from a second surface of the second substrate;
• bonding the first surface of the first substrate and the second surface of the second substrate together, such that the recess, the first electrode, the piezoelectric layer, and the second electrode at least partially overlap when viewed along a vertical direction to form an overlapping area;
• and
• removing the carrier and the adhesion layer.

An acoustic wave device comprising:

• a first substrate comprising:
• a first surface;
• a first electrode, a piezoelectric layer, and a second electrode, wherein the first electrode, the piezoelectric layer, and the second electrode are stacked in sequence, and the first electrode is exposed from the first surface;
• and
• a first frame at least partially surrounding the first electrode;
• and
• a second substrate comprising:
• a second surface;
• a second bulkplate;
• a recess disposed in the second bulkplate and recessed from the second surface;
• and
• a second frame disposed in the second bulkplate;
• wherein the first surface of the first substrate and the second surface of the second substrate are bonded together;
• the recess, the first electrode, the piezoelectric layer, and the second electrode at least partially overlap when viewed along a vertical direction;
• the first substrate and the second substrate form a sealed cavity at the recess;
• and
• the second frame at least partially surrounds the sealed cavity.