Abstract: Aspects of this disclosure relate to bulk acoustic wave resonators. A bulk acoustic wave resonator includes a patterned mass loading layer that affects a resonant frequency of the bulk acoustic wave resonator. The patterned mass loading layer can have a duty factor in a range from 0.2 to 0.8 in a main acoustically active region of the bulk acoustic wave resonator. Related filters, acoustic wave dies, radio frequency modules, wireless communications devices, and methods are disclosed.

Abstract: Aspects of this disclosure relate to methods of manufacturing bulk acoustic wave resonators. During a common processing step, a first patterned mass loading layer for a first bulk acoustic wave resonator is formed and a second patterned mass loading layer for a second bulk acoustic wave resonator is formed. The first patterned mass loading layer has a different density than the second patterned mass loading layer.

Abstract: Aspects of this disclosure relate to bulk acoustic wave resonators with patterned mass loading layers. Two different bulk acoustic wave resonators of an acoustic wave filter and/or an acoustic wave die have respective patterned mass loading layers with different densities. The patterned mass loading layers contribute to the two different bulk acoustic wave resonators having different respective resonant frequencies. Related bulk acoustic wave devices, filters, acoustic wave dies, radio frequency modules, wireless communication devices, and methods are disclosed.

Abstract: Aspects of this disclosure relate bulk acoustic wave resonators with a patterned mass loading layer at least contributing to a difference in mass loading between a main acoustically active region of the bulk acoustic wave resonator and a recessed frame region of the bulk acoustic wave resonator. Related methods of manufacturing can involve forming the patterned mass loading layer in the main acoustically active region and the recessed frame region in a common processing step such that the patterned mass loading layer has a higher density in the main acoustically active region than in the recessed frame region.

Abstract: Aspects of this disclosure relate to bulk acoustic wave resonators. A bulk acoustic wave resonator includes a patterned mass loading layer that affects a resonant frequency of the bulk acoustic wave resonator. The patterned mass loading layer can have a duty factor in a range from 0.2 to 0.8 in a main acoustically active region of the bulk acoustic wave resonator. Related filters, acoustic wave dies, radio frequency modules, wireless communications devices, and methods are disclosed.

Abstract: Aspects of this disclosure relate to a bulk acoustic wave device with a multi-layer raised frame. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a multi-layer raised frame structure configured to cause lateral energy leakage from a main acoustically active region of the bulk acoustic wave device to be reduced. The multi-layer raised frame structure includes a first raised frame layer embedded in the piezoelectric layer and a second raised frame layer. The first raised frame layer has a lower acoustic impedance than the piezoelectric layer.

Abstract: Aspects of this disclosure relate to a bulk acoustic wave device with a multi-gradient raised frame. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a multi-gradient raised frame structure. The multi-gradient raised frame structure includes a first raised frame layer and a second raised frame layer. The second raised frame layer extends beyond the first raised frame layer. The second raised frame layer is tapered on opposing sides.

Abstract: Aspects of this disclosure relate to a bulk acoustic wave device with a multi-gradient raised frame. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a multi-gradient raised frame structure configured to cause lateral energy leakage from a main acoustically active region of the bulk acoustic wave device to be reduced. The multi-gradient raised frame structure is tapered on opposing sides.