Granted Patent B2

US 12,620,961 · App. 17/831,381 · Granted May 5, 2026

Inventors: Albert Cardona (Santa Barbara, CA); Chris O'Brien (San Diego, CA); Akanksha Saha (Santa Barbara, CA); Andrew Kay (Provo, UT)

Assignee: MURATA MANUFACTURING CO., LTD.

H03H9/02228

Abstract

Claims (20)

1 . An acoustic resonator device comprising:

a substrate having a surface, the substrate comprising a substrate material;

an intervening oxide layer on the surface of the substrate and having a cavity, a thickness of the intervening oxide layer defining a depth of the cavity, the substrate comprising a vertical etch-stop material that includes silicon;

a piezoelectric layer having opposing front and back surfaces, the back surface attached to the intervening oxide layer and the piezoelectric layer having a portion that forms a diaphragm that is over the cavity in the intervening oxide layer;

an interdigital transducer (IDT) on the front surface of the piezoelectric layer and having interleaved fingers on the diaphragm; and

lateral fences in the piezoelectric layer and intervening oxide layer that define a perimeter of the cavity, the lateral fences comprising a lateral etch-stop material that includes at least one of silicon oxide, silicon nitride, aluminum oxide, oxynitride, chromium, aluminum and platinum,

wherein the piezoelectric layer includes one or more holes extending therethrough and that do not overlap the lateral fences in a direction perpendicular to the surface of the substrate.

2 . The device of claim 1 wherein the intervening oxide layer comprises a device layer thickness of silicon oxide material on the silicon substrate.

3 . The device of claim 1 wherein:

the piezoelectric layer and the IDT are configured such that a radio frequency signal applied to the IDT excites a primary shear acoustic mode in the diaphragm,

the primary shear acoustic mode is a bulk shear mode where acoustic energy propagates along a direction substantially orthogonal to the front and back surfaces of piezoelectric layer, which is also transverse to a direction of an electric field generated by the interleaved fingers of the IDT, and

the piezoelectric layer comprising one of lithium niobate and lithium tantalate.

4 . The device of claim 1 wherein the substrate comprises:

a device portion having the intervening oxide layer, wherein the cavity extends from the back surface of the piezoelectric layer through the device portion to the substrate.

5 . The device of claim 4 wherein:

the substrate is silicon; and

the intervening oxide layer is silicon dioxide.

6 . The device of claim 1 wherein:

the cavity is formed by a frontside membrane release etch process that etches the intervening oxide layer; and

the lateral fences and substrate are substantially impervious to the etch process.

Assignments (2)

Continuity (2)

References Cited (228)