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.

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.

A method of manufacture for an acoustic resonator or filter device. In an example, the present method can include forming metal electrodes with different geometric areas and profile shapes coupled to a piezoelectric layer overlying a substrate. These metal electrodes can also be formed within cavities of the piezoelectric layer or the substrate with varying geometric areas. Combined with specific dimensional ratios and ion implantations, such techniques can increase device performance metrics. In an example, the present method can include forming various types of perimeter structures surrounding the metal electrodes, which can be on top or bottom of the piezoelectric layer. These perimeter structures can use various combinations of modifications to shape, material, and continuity. These perimeter structures can also be combined with sandbar structures, piezoelectric layer cavities, the geometric variations previously discussed to improve device performance metrics.

A method of manufacture for an acoustic resonator or filter device. In an example, the present method can include forming metal electrodes with different geometric areas and profile shapes coupled to a piezoelectric layer overlying a substrate. These metal electrodes can also be formed within cavities of the piezoelectric layer or the substrate with varying geometric areas. Combined with specific dimensional ratios and ion implantations, such techniques can increase device performance metrics. In an example, the present method can include forming various types of perimeter structures surrounding the metal electrodes, which can be on top or bottom of the piezoelectric layer. These perimeter structures can use various combinations of modifications to shape, material, and continuity. These perimeter structures can also be combined with sandbar structures, piezoelectric layer cavities, the geometric variations previously discussed to improve device performance metrics.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.

A substrate for a surface acoustic wave device or bulk acoustic wave device, comprising a support substrate and an piezoelectric layer on the support substrate, wherein the support substrate comprises a semiconductor layer on a stiffening substrate having a coefficient of thermal expansion that is closer to the coefficient of thermal expansion of the material of the piezoelectric layer than that of silicon, the semiconductor layer being arranged between the piezoelectric layer and the stiffening substrate.

A substrate for a surface acoustic wave device or bulk acoustic wave device, comprising a support substrate and an piezoelectric layer on the support substrate, wherein the support substrate comprises a semiconductor layer on a stiffening substrate having a coefficient of thermal expansion that is closer to the coefficient of thermal expansion of the material of the piezoelectric layer than that of silicon, the semiconductor layer being arranged between the piezoelectric layer and the stiffening substrate.

An acoustic resonator includes: a resonating unit including a resonating unit including a piezoelectric layer and first and second electrodes disposed on a lower side and an upper side of the piezoelectric layer, respectively; a substrate disposed on a lower side of the resonating unit; a support unit providing a cavity between the substrate and the resonating unit; and an intermediate metal layer separated from the second electrode and disposed in the resonating unit such that at least a portion thereof is surrounded by the piezoelectric layer and the second electrode.

A bulk acoustic resonator includes: a substrate; a first electrode disposed on the substrate; a piezoelectric layer disposed to cover at least a portion of the first electrode; a second electrode disposed to cover at least a portion of the piezoelectric layer; a metal pad connected to the first electrode and the second electrode; and a protective layer disposed to cover at least the metal pad.