Plate wave devices with wave confinement structures and fabrication methods

A micro-electrical-mechanical system (MEMS) guided wave device comprising:

• a single crystal piezoelectric layer;
• a plurality of electrodes arranged in or on the single crystal piezoelectric layer and configured for transduction of a lateral acoustic wave in the single crystal piezoelectric layer;
• and
• at least one guided wave confinement structure arranged proximate to the single crystal piezoelectric layer and configured to confine a laterally excited wave having a wavelength λ in the single crystal piezoelectric layer, wherein each guided wave confinement structure of the at least one guided wave confinement structure comprises a thickness of less than 5 λ, and the at least one guided wave confinement structure comprises a fast wave propagation layer;
• wherein:
• the plurality of electrodes comprises an interdigital transducer (IDT) including a first group of electrodes of a first polarity and a second group of electrodes of a second polarity opposing the first polarity;
• the single crystal piezoelectric layer includes a plurality of recessed regions;
• and
• the second group of electrodes is arranged in the plurality of recessed regions, such that the second group of electrodes is non-coplanar with the first group of electrodes.

A micro-electrical-mechanical system (MEMS) guided wave device comprising:

• a single crystal piezoelectric layer comprising a first surface and a second surface opposing the first surface;
• a plurality of electrodes arranged in or on the single crystal piezoelectric layer and configured for transduction of a lateral acoustic wave in the single crystal piezoelectric layer;
• and
• at least one guided wave confinement structure arranged proximate to the single crystal piezoelectric layer and configured to confine a laterally excited wave having a wavelength λ in the single crystal piezoelectric layer, wherein each guided wave confinement structure of the at least one guided wave confinement structure comprises a thickness of less than 5 λ, and the at least one guided wave confinement structure comprises a fast wave propagation layer;
• wherein the MEMS guided wave device comprises at least one of the following features:
• (i) the plurality of electrodes comprises a first interdigital transducer (IDT) arranged on the first surface and a comprises a second IDT arranged on the second surface, or (ii) the at least one guided wave confinement structure comprises a first guided wave confinement structure proximate to the first surface, and comprises a second guided wave confinement structure proximate to the second surface.

A micro-electrical-mechanical system (MEMS) guided wave device comprising:

• a single crystal piezoelectric layer comprising a first surface and a second surface opposing the first surface;
• a plurality of electrodes arranged in or on the single crystal piezoelectric layer and configured for transduction of a lateral acoustic wave in the single crystal piezoelectric layer;
• and
• at least one guided wave confinement structure arranged proximate to the single crystal piezoelectric layer and configured to confine a laterally excited wave having a wavelength λ in the single crystal piezoelectric layer, wherein each guided wave confinement structure of the at least one guided wave confinement structure comprises a thickness of less than 5 λ, and the at least one guided wave confinement structure comprises a fast wave propagation layer;
• wherein:
• the plurality of electrodes and the single crystal piezoelectric layer in combination comprise a periodically poled transducer in which the single crystal piezoelectric layer comprises a plurality of laterally alternating regions of different polarity, and in which the plurality of electrodes comprises a first solid metal electrode arranged on the first surface and comprises a second solid metal electrode arranged on the second surface;
• and
• at least one slow wave propagation layer is present between the periodically poled transducer and the at least one guided wave confinement structure.

A micro-electrical-mechanical system (MEMS) guided wave device comprising:

• a segmented single crystal piezoelectric layer;
• a plurality of electrodes arranged in or on the single crystal piezoelectric layer and configured for transduction of a lateral acoustic wave in the single crystal piezoelectric layer, wherein the plurality of electrodes comprises a segmented layer of first electrodes and comprises a substantially continuous layer of a second electrode;
• and
• at least one guided wave confinement structure arranged proximate to the single crystal piezoelectric layer and configured to confine a laterally excited wave having a wavelength λ in the single crystal piezoelectric layer, wherein each guided wave confinement structure of the at least one guided wave confinement structure comprises a thickness of less than 5 λ, and the at least one guided wave confinement structure comprises a fast wave propagation layer;
• wherein the segmented single crystal piezoelectric layer is arranged between the segmented layer of first electrodes and the substantially continuous layer of the second electrode, with segments of the segmented single crystal piezoelectric layer being substantially registered with segments of the segmented layer of first electrodes.

A micro-electrical-mechanical system (MEMS) guided wave device comprising:

• a single crystal piezoelectric layer comprising a first thickness region and a second thickness region, wherein a thickness of the first thickness region differs from a thickness of the second thickness region;
• a first plurality of electrodes arranged on or adjacent to the first thickness region and configured for transduction of a first lateral acoustic wave having a wavelength λ1 in the first thickness region;
• a second plurality of electrodes arranged on or adjacent to the second thickness region and configured for transduction of a second lateral acoustic wave having a wavelength λ2 in the second thickness region, wherein λ2 differs from λ1;
• and
• at least one guided wave confinement structure arranged proximate to the single crystal piezoelectric layer, configured to confine the first lateral acoustic wave in the first thickness region, and configured to confine the second lateral acoustic wave in the second thickness region.