An acoustic resonator forms a component of an FBAR filter that includes a trap-rich layer to avoid parasitic conduction by degrading carrier lifetimes of a free charge carriers. The acoustic resonator has a first electrode, a second electrode disposed parallel to the first planar portion and a piezoelectric layer disposed between and contacting both the first and second planar electrodes. A silicon-based a support layer is bonded to the second electrode and includes a trap region. The acoustic resonator may be manufactured by (a) depositing the trap region on the support layer; (b) oxidizing a surface of the trap region; (c) depositing a bonding layer on the oxidized surface of the trap region; (d) bonding a first electrode to the bonding layer; (e) contacting a first side of a piezoelectric layer to the electrode; and (f) contacting a second side of the piezoelectric layer a second electrode.

A transducer structure for a surface acoustic device comprises a composite substrate comprising a piezoelectric layer, a pair of inter-digitated comb electrodes, comprising a plurality of electrode means with a pitch p satisfying the Bragg condition, wherein the inter-digitated comb electrodes are embedded in the piezoelectric layer such that, in use, the excitation of a wave propagating mode in the volume of the electrode means is taking place and is the predominant propagating mode of the structure. The present disclosure relates also to an acoustic wave device comprising at least one transducer structure as described above and to a method for fabricating the transducer structure. The present disclosure relates also to the use of the frequency of the bulk wave propagating in the electrode means of the transducer structure in an acoustic wave device to generate contribution at high frequency, in particular, above 3 GHz.

A method of forming a resonator includes forming top and bottom dielectric structures over a substrate. A piezoelectric layer is formed between the top and bottom dielectric structures. A bottom electrode is formed between the piezoelectric layer and the bottom dielectric structure, and a top electrode is formed between the piezoelectric layer and the top dielectric structure. A metal layer is formed over the top dielectric structure and is patterned, thereby forming a first contact pad making electrical contact to the top electrode, a second contact pad making electrical contact with the bottom electrode, and a mass bias located over the top dielectric structure.

An apparatus is disclosed for partially suspending a piezoelectric layer using a dielectric. In an example aspect, the apparatus includes a microacoustic filter with a substrate layer, a piezoelectric layer, an electrode structure that is in contact with the piezoelectric layer, and a dielectric. The electrode structure includes multiple fingers arranged across a plane having a first axis that is perpendicular to the multiple fingers and a second axis that is parallel to the multiple fingers. The dielectric is configured to separate the piezoelectric layer from the substrate layer and define a cavity between the piezoelectric layer and the substrate layer. The dielectric is also configured to support the piezoelectric layer across at least three points along the first axis.

In a crystal resonator plate (2), a support part (24) extends from only one corner part positioned in the +X direction and in the −Z′ direction of a vibrating part (22) to an external frame part (23) in the −Z′ direction. The vibrating part (22) and at least part of the support part (24) form an etching region (Eg) having a thickness thinner than a thickness of the external frame part (23). A stepped part is formed at a boundary of the etching region (Eg), and a first lead-out wiring (223) is formed over the support part (24) to the external frame part (23) so as to overlap with the stepped part. At least part of the stepped part that is superimposed on the first lead-out wiring (223) is formed so as not to be parallel to the X axis in plan view.

An acoustic wave device includes a piezoelectric layer and first and second electrodes. The first and second electrodes face each other in a direction intersecting with a thickness direction of the piezoelectric layer. The acoustic wave device uses a bulk wave of a thickness-shear primary mode. A material of the piezoelectric layer is lithium niobate or lithium tantalate. The piezoelectric layer is on a first main surface of the silicon substrate. The acoustic wave device further includes a trap region on a side of a second main surface of the piezoelectric layer.

An apparatus and method for making an acoustic filter package where the apparatus includes a base layer; a support layer disposed on the base layer; a piezoelectric structure disposed on the support layer; wherein the piezoelectric structure comprises: a piezoelectric layer; a top electrode on a top surface of the piezoelectric layer; a bottom electrode on a bottom surface of the piezoelectric layer; a contact pad coupled to the bottom electrode that extends through an opening in the piezoelectric layer and is coupled to the bottom electrode or the top electrode; and a corrosion resistant pad disposed on the contact pad; and a capping structure disposed on the piezoelectric structure.

A bulk-acoustic wave resonator is provided. The bulk-acoustic wave resonator comprises a substrate comprising an external connection electrode; a connection layer connected to the external connection electrode and disposed on the substrate; a first electrode disposed to cover at least a portion of the connection layer; a piezoelectric layer disposed to cover at least a portion of the first electrode; and a second electrode disposed to cover at least a portion of the piezoelectric layer. The connection layer may be disposed to surround a cavity and may be connected to the first electrode and the second electrode.

An acoustic resonator is disclosed. The acoustic resonator comprises a substrate, a first electrode, a second electrode and a piezoelectric layer positioned between the first electrode and the second electrode. An acoustic reflector is positioned between the first electrode and the substrate. An active area comprises a region of contacting overlap of the acoustic reflector, the first electrode, the piezoelectric layer and the second electrode. A gap region extends around the active area.

Bulk acoustic wave (BAW) resonators, and electrical filters that incorporate the BAW resonators, are described. Generally, the BAW resonators comprise a substrate comprising an acoustic reflector; a first electrode disposed over the acoustic reflector; a piezoelectric layer disposed over the first electrode, the piezoelectric layer comprising scandium-doped aluminum nitride (ASN); a diffusion barrier layer disposed over the piezoelectric layer; and a second electrode disposed over the diffusion barrier layer. The diffusion barrier layer configured to prevent diffusion of material of the first electrode into the piezoelectric layer.