# US 2021/0280771 A1 · Substituted aluminum nitride for improved acoustic wave filters

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- Number: US 2021/0280771 A1
- Document ID: US20210280771A1
- Status: Published application
- Kind: A1
- Application number: 17/308,168
- Filed: 2021-05-05
- Published: 2021-09-09
- Earliest claimed: 2017-07-07
- Assignees: Skyworks Solutions, Inc.
- Applicants: Skyworks Solutions, Inc.
- Inventors: Michael David Hill; Peter Ledel Gammel
- Web page: https://patentgrep.com/patent/US20210280771A1

## CPC

- H10N 30/853: Ceramic compositions
- C01B 21/072: with aluminium
- H03H 9/02031: {consisting of ceramic}
- H03H 9/54: comprising resonators of piezoelectric or electrostrictive material (comprising resonators using surface acoustic waves H03H9/64)
- C01P 2002/52: containing elements as dopants
- C01P 2002/54: one element only
- C01P 2002/76: by a space-group or by other symmetry indications
- C01P 2002/77: by unit-cell parameters, atom positions or structure diagrams
- C01P 2006/40: Electric properties
- H03H 3/02: for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence)
- H03H 9/205: having multiple resonators (crystal tuning forks H03H9/21)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

An acoustic wave resonator comprises a piezoelectric material formed of aluminum nitride (AlN) doped with calcium (Ca) to enhance performance of the acoustic wave resonator.

## Claims

### Claim 1

An acoustic wave resonator comprising a piezoelectric material formed of aluminum nitride doped with calcium to enhance performance of the acoustic wave resonator.

### Claim 2 (depends on 1)

The acoustic wave resonator of claim 1, wherein the calcium is charge balanced with at least one of silicon and germanium and the piezoelectric material has a chemical formula of one of
Al1-2xCaxSixN (0<x<1); or
Al1-2xCaxGexN (0<x<1).

### Claim 3 (depends on 1)

An acoustic wave filter including the acoustic wave resonator of claim 1.

### Claim 4 (depends on 3)

The acoustic wave filter of claim 3 wherein the acoustic wave resonator is a bulk acoustic wave resonator.

### Claim 5 (depends on 4)

The acoustic wave filter of claim 4 wherein the bulk acoustic wave resonator is one of a film bulk acoustic wave resonator, a Lamb wave resonator, or a surface mounted resonator.

### Claim 6 (depends on 4)

The acoustic wave filter of claim 4 wherein the acoustic wave filter is a radio frequency filter.

### Claim 7 (depends on 6)

An electronics module including the acoustic wave filter of claim 6.

### Claim 8 (depends on 7)

An electronic device including the electronics module of claim 7.

### Claim 9 (depends on 1)

The acoustic wave resonator of claim 1 wherein the piezoelectric material has a Wurtzite crystal structure.

### Claim 10

A method of forming an acoustic wave resonator comprising:
forming a piezoelectric film formed of aluminum nitride doped with calcium; and
depositing electrodes on the piezoelectric film to form the acoustic wave resonator.

### Claim 11 (depends on 10)

The method of claim 10 wherein depositing the electrodes on the piezoelectric film in includes depositing a first electrode on a top surface of the piezoelectric film and depositing a second electrode on a bottom surface of the piezoelectric film.

### Claim 12 (depends on 11)

The method of claim 11 wherein the acoustic wave resonator is a film bulk acoustic wave resonator and the method further comprises defining a cavity below the lower surface of the piezoelectric film.

### Claim 13 (depends on 11)

The method of claim 11 wherein the acoustic wave resonator is a Lamb wave resonator and depositing the first electrode on the top surface of the piezoelectric film comprises depositing interdigital transducer electrodes on the top surface of the piezoelectric film.

### Claim 14 (depends on 11)

The method of claim 11 wherein the acoustic wave resonator is a solidly mounted resonator and the method further comprises forming the piezoelectric film on a top surface of a Bragg reflector.

### Claim 15

An acoustic wave resonator including a film of piezoelectric material and an electrode disposed on the film of piezoelectric material, the film of piezoelectric material comprising:
AlN doped with cations of one or more elements selected from the group consisting of:
a) one of Sb, or Nb;
b) Cr in combination with one or more of B, Sc, Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, or Yb;
c) one of Nb and Ta in combination with one of Li, Ca, Ni, or Co;
d) Ca in combination with one of Si or Ge;
e) Mg in combination with one of Si or Ge; or
f) one or more of Co, Sb, Ta, Nb, Si, or Ge in combination with one or more of Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, or Yb;
the cations at least partially substituting for Al in a crystal structure of the piezoelectric material.

### Claim 16 (depends on 15)

The acoustic wave resonator of claim 15 wherein the piezoelectric material of has a Wurtzite crystal structure.

### Claim 17 (depends on 15)

The acoustic wave resonator of claim 15 configured as a solidly mounted resonator.

### Claim 18 (depends on 15)

The acoustic wave resonator of claim 15 configured as a film bulk acoustic resonator.

### Claim 19 (depends on 15)

A filter including the acoustic wave resonator of claim 15.

### Claim 20 (depends on 19)

The filter of claim 19 having a passband in the radio frequency band.

### Claim 21 (depends on 19)

An electronic device module including the filter of claim 19.

### Claim 22 (depends on 21)

An electronic device including the electronic device module of claim 21.

### Claim 23 (depends on 22)

The electronic device of claim 22 wherein the electronic device module is a radio frequency electronic device module.