Bulk acoustic wave device including patterned acoustic mirror layers to reduce effective thickness and related methods

A method of manufacturing a bulk acoustic wave (BAW) device, the method comprising:

• forming a piezoelectric layer;
• forming a first electrode on a first side of the piezoelectric layer;
• forming a second electrode on a second side of the piezoelectric layer;
• and
• forming an acoustic mirror on a surface of the second electrode, the acoustic mirror comprising a plurality of layers comprising a first patterned layer;
• wherein:
• the first patterned layer comprises a first region of a first material and a second region of the first material;
• the first region and the second region are discrete regions separated from each other by a second material different from the first material;
• the first patterned layer comprises the first material and the second material disposed in a first area of the first patterned layer corresponding to the second electrode;
• the first area extends parallel to a surface of the second electrode in a first direction and a second direction orthogonal to the first direction;
• and
• the plurality of layers further comprising:
• a first isolation layer comprising the second material disposed between the second electrode and the first patterned layer;
• a substrate;
• a second isolation layer comprising the second material disposed between the first patterned layer and the substrate;
• and
• a non-patterned layer comprising a single region of the first material in the first area corresponding to the second electrode.

An acoustic filter package comprising:

• a substrate;
• and
• at least one bulk acoustic wave (BAW) device disposed on the substrate, the BAW device comprising:
• a piezoelectric layer;
• a first electrode on a first side of the piezoelectric layer;
• a second electrode on a second side of the piezoelectric layer;
• and
• an acoustic mirror on a surface of the second electrode, the acoustic mirror comprising a plurality of layers comprising a first patterned layer;
• wherein:
• the first patterned layer comprises a first region of a first material and a second region of the first material;
• the first region and the second region are discrete regions separated from each other by a second material different from the first material;
• the first patterned layer comprises the first material and the second material disposed in a first area of the first patterned layer corresponding to the second electrode;
• the first area extends parallel to a surface of the second electrode in a first direction and a second direction orthogonal to the first direction;
• and
• the plurality of layers further comprising:
• a first isolation layer comprising the second material disposed between the second electrode and the first patterned layer;
• a substrate;
• a second isolation layer comprising the second material disposed between the first patterned layer and the substrate;
• and
• a non-patterned layer comprising a single region of the first material in the first area corresponding to the second electrode.

A bulk acoustic wave (BAW) device comprising:

• a piezoelectric layer;
• a first electrode disposed on a first side of the piezoelectric layer;
• a second electrode disposed on a second side of the piezoelectric layer;
• and
• an acoustic mirror disposed between the second electrode and a substrate, the acoustic mirror comprising a plurality of layers comprising a first patterned layer and a non-patterned layer;
• wherein:
• the first patterned layer comprises a first region of a first material and a second region of the first material;
• the first region and the second region are discrete regions separated from each other by a second material different from the first material;
• the first patterned layer comprises the first material and the second material disposed in a first area of the first patterned layer corresponding to the second electrode;
• and
• the non-patterned layer comprises a single region of the first material in the first area corresponding to the second electrode.