IP Library › Granted Patent US 12,597,902
Granted Patent B2
US 12,597,902 · App. 17/742,827 · Granted Apr 7, 2026

Piezoelectric bulk layers with tilted c-axis orientation and methods for making the same

Inventors: Derya Deniz (McKinney, TX); Robert Kraft (Plano, TX); John Belsick (Bend, OR)
Assignee: Qorvo US, Inc.
H03H3/02C23C14/0036C23C14/226H01J37/3408H01J37/3447H03H9/02007H03H9/02031H03H9/54
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Quick Facts
Patent No.
US 12,597,902
App. No.
17/742,827
Granted
Apr 7, 2026
Kind
B2
Abstract

Bulk acoustic wave resonator structures include a bulk layer with inclined c-axis hexagonal crystal structure piezoelectric material supported by a substrate. The bulk layer may be prepared without first depositing a seed layer on the substrate. The bulk material layer has a c-axis tilt of about 32 degrees or greater. The bulk material layer may exhibit a ratio of shear coupling to longitudinal coupling of 1.25 or greater during excitation. A method for preparing a crystalline bulk layer having a c-axis tilt includes depositing a bulk material layer directly onto a substrate at an off-normal incidence. The deposition conditions may include a pressure of less than 5 mTorr and a deposition angle of about 35 degrees to about 85 degrees.

Claims (26)

1 . A piezoelectric structure with enhanced shear mode coupling, comprising:

a substrate comprising a wafer or a portion thereof; and

a bulk material layer with an inclined c-axis tilt, wherein the bulk material layer is deposited directly onto the substrate without first depositing a seed layer, at an off-normal incidence angle under deposition conditions comprising a pressure of less than 5 mTorr; and

wherein the piezoelectric structure exhibits a ratio of shear coupling to longitudinal coupling of 1.25 or greater during excitation.

2 . The piezoelectric structure of claim 1 , wherein the pressure is from about 0.5 mTorr to about 4.5 mTorr.

3 . The piezoelectric structure of claim 1 , wherein the pressure is from about 1 mTorr to about 4 mTorr.

4 . The piezoelectric structure of claim 1 , wherein the off-normal incidence angle is from about 35 degrees to about 85 degrees.

5 . The piezoelectric structure of claim 1 , wherein the c-axis tilt of the bulk material layer ranges from about 35 degrees to about 85 degrees.

6 . A bulk acoustic wave resonator comprising the piezoelectric structure of claim 1 , and further comprising a first electrode and a second electrode, wherein at least a portion of the bulk material layer is between the first electrode and the second electrode.

7 . The piezoelectric structure of claim 1 , wherein the bulk material layer is deposited using a linear sputtering apparatus.

8 . The piezoelectric structure of claim 1 , wherein the deposition conditions further comprise a temperature of 50° C. to 300° C.

9 . The piezoelectric structure of claim 1 , wherein the deposition conditions further comprise a deposition distance between a target surface and the substrate of 50 mm to 200 mm.

10 . The piezoelectric structure of claim 1 , wherein the deposition conditions further comprise a gas ratio of argon to reacting gas of 1:10 to 10:10.

11 . A piezoelectric structure with enhanced shear mode coupling comprising:

a substrate comprising a wafer or a portion thereof; and

a bulk material layer deposited directly onto the substrate without first depositing a seed layer, at an off-normal incidence angle, wherein the bulk material layer has a c-axis tilt that ranges from about 35 degrees to about 85 degrees; and

wherein the bulk material layer exhibits a ratio of shear coupling to longitudinal coupling of 1.25 or greater during excitation.

12 . The piezoelectric structure of claim 11 , wherein the bulk material layer has a thickness of about 1,000 Angstroms to about 30,000 Angstroms.

13 . The piezoelectric structure of claim 11 , wherein the bulk material layer comprises AlN.

14 . A bulk acoustic wave resonator comprising the piezoelectric structure of claim 11 , and further comprising a first electrode and a second electrode, wherein at least a portion of the bulk material layer is between the first electrode and the second electrode.

15 . A piezoelectric structure with a preselected c-axis tilt angle comprising:

a substrate comprising a wafer or a portion thereof; and

a bulk material layer deposited directly onto the substrate without first depositing a seed layer, at an off-normal incidence angle, wherein a plurality of crystals in the bulk material layer are substantially parallel to one another and are substantially oriented in a direction of the preselected c-axis tilt angle; and

wherein the piezoelectric structure exhibits a ratio of shear coupling to longitudinal coupling of 1.25 or greater during excitation.

16 . The piezoelectric structure of claim 15 , wherein the c-axis tilt of the bulk material layer ranges from about 35 degrees to about 85 degrees.

17 . A bulk acoustic wave resonator comprising the piezoelectric structure of claim 15 , and further comprising a first electrode and a second electrode, wherein at least a portion of the bulk material layer is between the first electrode and the second electrode.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded May 13, 2022
From: DENIZ, DERYA; BELSICK, JOHN; KRAFT, ROBERT
To: QORVO US, INC.
Reel/Frame 060068/0345 →
Continuity (3)
Continuation 16359575 · Mar 20, 2019
Provisional Application 62646212 · Mar 21, 2018
Related Publication 20220271726A1 · Aug 25, 2022
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