Acoustic resonator comprising acoustic reflector, frame and collar

Patent metadata

Field	Value
Publication number	US-9525397-B2
Application number	US-201414180596-A
Country	US
Kind code	B2
Filing date	Feb 14, 2014
Priority date	Mar 29, 2011
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

A solidly mounted resonator (SMR) device includes an acoustic reflector having stacked acoustic reflector layer pairs, each of which includes a low acoustic impedance layer formed of low acoustic impedance material stacked on a high acoustic impedance layer formed of high acoustic impedance material. The SMR device further includes a bottom electrode disposed on the acoustic reflector, a piezoelectric layer disposed on the bottom electrode, and a top electrode disposed on the piezoelectric layer. A collar is formed outside a main active region defined by an overlap between the top electrode, the piezoelectric layer and the bottom electrode, and at least one frame is disposed within the main active region. The collar has an inner edge substantially aligned with a boundary of or overlapping the main active region, and the at least one frame has an outer edge substantially aligned with the boundary of the main active region.

First claim

The invention claimed is:

1. A solidly mounted resonator (SMR) device, comprising:
an acoustic reflector disposed on a substrate, the acoustic reflector comprising a plurality of stacked acoustic reflector layer pairs, each acoustic reflector layer pair comprising a low acoustic impedance layer formed of low acoustic impedance material stacked on a high acoustic impedance layer formed of high acoustic impedance material;
a bottom electrode disposed on the low acoustic impedance layer of a top acoustic impedance layer pair of the acoustic reflector;
a piezoelectric layer disposed on the bottom electrode;
a top electrode disposed on the piezoelectric layer;
a collar formed outside a main active region defined by an overlap between the top electrode, the piezoelectric layer and the bottom electrode, the collar having an inner edge substantially aligned with a boundary of or overlapping the main active region; and
at least one frame disposed within the main active region and having an outer edge substantially aligned with the boundary of the main active region,
wherein the collar defines a collar region having a cutoff frequency that is substantially the same as a cutoff frequency of the main active region, and
wherein the collar is formed on a top surface of the top electrode and a planarization layer adjacent the top electrode or on a top surface of the bottom electrode between the bottom electrode and the piezoelectric layer.

2. The SMR device of claim 1 , wherein the low acoustic impedance material comprises borosilicate glass (BSG) or tetra-ethyl-ortho-silicate (TEOS).

3. The SMR device of claim 1 , wherein the collar comprises borosilicate glass, silicon dioxide, carbon-doped silicon oxide, silicon carbide, silicon nitride, aluminum oxide, aluminum nitride, zinc oxide, lead zirconium titanate, diamond, diamond-like carbon, tungsten, molybdenum or iridium.

4. The SMR device of claim 1 , wherein the at least one frame comprises copper, molybdenum, aluminum, tungsten, iridium, borosilicate glass, carbon-doped silicon oxide, silicon carbide, silicon nitride, aluminum oxide, aluminum nitride, zinc oxide, lead zirconium titanate, diamond or diamond-like carbon.

5. The SMR device of claim 1 , wherein the piezoelectric layer is doped with at least one rare earth element.

6. The SMR device of claim 1 , wherein the low acoustic impedance material of at least one of the plurality of stacked acoustic reflector layer pairs comprises a temperature compensating material having a positive temperature coefficient for offsetting at least a portion of negative temperature coefficients of the piezoelectric layer, the bottom electrode and the top electrode.

7. A solidly mounted resonator (SMR) device, comprising:
an acoustic reflector disposed on a substrate, the acoustic reflector comprising a plurality of stacked acoustic reflector layer pairs, each acoustic reflector layer pair comprising a low acoustic impedance layer formed of low acoustic impedance material stacked on a high acoustic impedance layer formed of high acoustic impedance material;
a bottom electrode disposed on the low acoustic impedance layer of a top acoustic impedance layer pair of the acoustic reflector;
a piezoelectric layer disposed on the bottom electrode;
a top electrode disposed on the piezoelectric layer;
a collar formed outside a main active region defined by an overlap between the top electrode, the piezoelectric layer and the bottom electrode, the collar having an inner edge substantially aligned with a boundary of or overlapping the main active region, wherein at least a portion of the collar is formed on a top surface of the bottom electrode or on a top surface of the top electrode; and
at least one frame disposed within the main active region and having an outer edge substantially aligned with the boundary of the main active region,
wherein the collar defines a collar region having a cutoff frequency that is substantially the same as a cutoff frequency of the main active region, and
wherein the collar is an electrically grounded collar.

8. A solidly mounted resonator (SMR) device, comprising:
an acoustic reflector disposed on a substrate, the acoustic reflector comprising a plurality of stacked acoustic reflector layer pairs, each acoustic reflector layer pair comprising a low acoustic impedance layer formed of low acoustic impedance material stacked on a high acoustic impedance layer formed of high acoustic impedance material;
a bottom electrode disposed on the low acoustic impedance layer of a top acoustic impedance layer pair of the acoustic reflector;
a piezoelectric layer disposed on the bottom electrode;
a top electrode disposed on the piezoelectric layer;
a collar formed outside a main active region defined by an overlap between the top electrode, the piezoelectric layer and the bottom electrode, the collar having an inner edge substantially aligned with a boundary of or overlapping the main active region, wherein at least a portion of the collar is formed on a top surface of the bottom electrode or on a top surface of the top electrode; and
at least one frame disposed within the main active region and having an outer edge substantially aligned with the boundary of the main active region, wherein the at least one frame comprises a frame disposed at a bottom portion of the top electrode.

9. The SMR device of claim 8 , wherein the frame disposed at the bottom portion of the top electrode comprises an add-on frame.

10. The SMR device of claim 8 , wherein the frame disposed at the bottom portion of the top electrode comprises a composite frame.

11. The SMR device of claim 8 , wherein the at least one frame comprises another frame disposed at one of a top portion or a bottom portion of the bottom electrode.

12. The SMR device of claim 8 , wherein the piezoelectric layer is doped with at least one rare earth element.

13. The SMR device of claim 8 , wherein the low acoustic impedance material of at least one of the plurality of stacked acoustic reflector layer pairs comprises a temperature compensating material having a positive temperature coefficient for offsetting at least a portion of negative temperature coefficients of the piezoelectric layer, the bottom electrode and the top electrode.

14. A solidly mounted resonator (SMR) device, comprising:
an acoustic reflector disposed on a substrate, the acoustic reflector comprising a plurality of stacked acoustic reflector layer pairs, each acoustic reflector layer pair comprising a low acoustic impedance layer formed of low acoustic impedance material stacked on a high acoustic impedance layer formed of high acoustic impedance material;
a bottom electrode disposed on the low acoustic impedance layer of a top acoustic impedance layer pair of the acoustic reflector;
a piezoelectric layer disposed on the bottom electrode;
a top electrode disposed on the piezoelectric layer;
a collar formed outside a main active region defined by an overlap between the top electrode, the piezoelectric layer and the bottom electrode, the collar having an inner edge substantially aligned with a boundary of or overlapping the main active region, wherein at least a portion of the collar is formed on a top surface of the bottom electrode or on a top surface of the top electrode; and
at least one frame disposed within the main active region and having an outer edge substantially aligned with the boundary of the main active region, wherein the at least one frame comprises a frame disposed at a bottom portion of the bottom electrode.

15. The SMR device of claim 14 , wherein the piezoelectric layer is doped

Assignees

• Avago Technologies General Ip

Inventors

• Burak Dariusz

Classifications

• H03H9/132

  characterized by a particular shape · CPC title

• H03H9/175

  Acoustic mirrors · CPC title

• H03H9/171

  implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type · CPC title

• H03H9/02102

  of temperature influence (cutting angles H03H9/02015) · CPC title

• H03H9/54

  comprising resonators of piezoelectric or electrostrictive material (comprising resonators using surface acoustic waves H03H9/64) · CPC title