# US 2017/0288122 A1 · Baw resonator having thin seed layer

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- Number: US 2017/0288122 A1
- Document ID: US20170288122A1
- Status: Published application
- Kind: A1
- Application number: 15/140,777
- Filed: 2016-04-28
- Published: 2017-10-05
- Earliest claimed: 2016-03-29
- Assignees: Avago Technologies General IP (Singapore) Pte. Ltd.
- Applicants: Avago Technologies General IP (Singapore) Pte. Ltd.
- Inventors: Qiang Zou; Chris Feng; Phil Nikkel; John Choy
- Web page: https://patentgrep.com/patent/US20170288122A1

## CPC

- H03H 9/02102: {of temperature influence (cutting angles H03H9/02015)}
- H03H 9/173: {Air-gaps}
- H03H 9/175: {Acoustic mirrors}
- H03H 2003/028: {for obtaining desired values of other parameters}
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)

## Abstract

A bulk acoustic wave (BAW) resonator comprises: a seed layer disposed over a substrate; a first electrode disposed over the seed layer; and a second electrode disposed over a piezoelectric layer. The seed layer has a thickness in the range of approximately 30 Å to approximately 150 Å.

## Claims

### Claim 1

A bulk acoustic wave (BAW) resonator comprising:
a seed layer disposed over a substrate, the seed layer having a thickness in the range of approximately 30 Å to approximately 150 Å;
a first electrode disposed on the seed layer; and
a second electrode disposed over a piezoelectric layer.

### Claim 2 (depends on 1)

The BAW resonator of claim 1, wherein the piezoelectric layer comprises aluminum nitride (AlN) doped with scandium (Sc).

### Claim 3 (depends on 2)

The BAW resonator of claim 2, wherein the seed layer comprises a piezoelectric material.

### Claim 4 (depends on 3)

The BAW resonator of claim 3, wherein the seed layer comprises scandium-doped aluminum nitride (ASN).

### Claim 5 (depends on 2)

The BAW resonator of claim 2, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.

### Claim 6 (depends on 4)

The BAW resonator of claim 4, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.

### Claim 7

A bulk acoustic wave (BAW) resonator comprising:
a seed layer disposed over a substrate, the seed layer having a thickness in the range of approximately 30 Å to approximately 60 Å;
a first electrode disposed on the seed layer; and
a second electrode disposed over a piezoelectric layer.

### Claim 8 (depends on 7)

The BAW resonator of claim 7, wherein the piezoelectric layer comprises aluminum nitride (AlN) doped with scandium (Sc).

### Claim 9 (depends on 8)

The BAW resonator of claim 8, wherein the seed layer comprises a piezoelectric material.

### Claim 10 (depends on 8)

The BAW resonator of claim 8, wherein the seed layer comprises scandium-doped aluminum nitride (ASN).

### Claim 11 (depends on 8)

The BAW resonator of claim 8, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.

### Claim 12 (depends on 10)

The BAW resonator of claim 10, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.

### Claim 13

A bulk acoustic wave (BAW) resonator comprising:
a seed layer disposed over a substrate, the seed layer having a thickness in the range of approximately 30 Å to approximately 60 Å;
a composite first electrode disposed over a substrate, the composite first electrode comprising:
a base electrode layer disposed on the seed layer;
a temperature compensation layer disposed on the base electrode layer;
a seed interlayer disposed on the temperature compensation layer, the seed interlayer having a thickness between about 30 Å and about 60 Å; and
a conductive interposer layer disposed on at least the seed interlayer, at least a portion of the conductive interposer layer contacting the base electrode layer;
a piezoelectric layer disposed on the composite first electrode, the piezoelectric layer comprising a piezoelectric material doped with scandium (Sc) for improving piezoelectric properties of the piezoelectric layer; and
a second electrode disposed on the piezoelectric layer,
wherein the piezoelectric layer has a negative temperature coefficient and the temperature compensation layer has a positive temperature coefficient that at least partially offsets the negative temperature coefficient of the piezoelectric layer.

### Claim 14 (depends on 13)

The BAW resonator of claim 13, wherein the piezoelectric layer comprises aluminum nitride (AlN) doped with scandium (Sc).

### Claim 15 (depends on 14)

The BAW resonator of claim 14, wherein the seed interlayer comprises a piezoelectric material.

### Claim 16 (depends on 15)

The BAW resonator of claim 15, wherein the seed interlayer comprises scandium-doped aluminum nitride (ASN).

### Claim 17 (depends on 15)

The BAW resonator of claim 15, wherein the seed layer comprises piezoelectric material.

### Claim 18 (depends on 17)

The BAW resonator of claim 17, wherein the seed interlayer comprises scandium-doped aluminum nitride (ASN).

### Claim 19 (depends on 14)

The BAW resonator of claim 14, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.

### Claim 20 (depends on 16)

The BAW resonator of claim 16, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.

### Claim 21 (depends on 18)

The BAW resonator of claim 18, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.

### Claim 22

A bulk acoustic wave (BAW) resonator comprising:
a seed layer disposed over a substrate, the seed layer having a thickness in the range of approximately 30 Å to approximately 150 Å;
a composite first electrode disposed over a substrate, the composite first electrode comprising:
a base electrode layer disposed on the seed layer;
a temperature compensation layer disposed over the base electrode layer;
a seed interlayer disposed over the temperature compensation layer, the seed interlayer having a thickness between about 30 Å and about 150 Å; and
a conductive interposer layer disposed on at least the seed interlayer, at least a portion of the conductive interposer layer contacting the base electrode layer;
a piezoelectric layer disposed on the composite first electrode, the piezoelectric layer comprising a piezoelectric material doped with scandium (Sc) for improving piezoelectric properties of the piezoelectric layer; and
a second electrode disposed over the piezoelectric layer, wherein the piezoelectric layer has a negative temperature coefficient and the temperature compensation layer has a positive temperature coefficient that at least partially offsets the negative temperature coefficient of the piezoelectric layer.

### Claim 23 (depends on 22)

The BAW resonator of claim 22, wherein the piezoelectric layer comprises aluminum nitride (AlN) doped with scandium (Sc).

### Claim 24 (depends on 22)

The BAW resonator of claim 22, wherein the seed interlayer comprises a piezoelectric material.

### Claim 25 (depends on 24)

The BAW resonator of claim 24, wherein the seed interlayer comprises scandium-doped aluminum nitride (ASN).

### Claim 26 (depends on 22)

The BAW resonator of claim 22, wherein the seed layer comprises piezoelectric material.

### Claim 27 (depends on 26)

The BAW resonator of claim 26, wherein the seed layer comprises scandium-doped aluminum nitride (ASN).

### Claim 28 (depends on 23)

The BAW resonator of claim 23, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.

### Claim 29 (depends on 25)

The BAW resonator of claim 25, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.

### Claim 30 (depends on 27)

The BAW resonator of claim 27, wherein a concentration of scandium (Sc) is in a range of approximately 5.0 atomic percent to approximately 18 atomic percent of the piezoelectric material.