BAW resonator with reduced heat build-up, HF filter comprising BAW resonator, duplexer comprising HF filter, and production method

Patent metadata

Field	Value
Publication number	US-10298202-B2
Application number	US-201515528713-A
Country	US
Kind code	B2
Filing date	Nov 10, 2015
Priority date	Nov 25, 2014
Publication date	May 21, 2019
Grant date	May 21, 2019

Abstract

The invention relates to a BAW resonator with reduced heat build-up. The heat build-up is reduced by a thermal bridge, which dissipates heat from the electro-acoustically active region to a support substrate, without impairing the acoustics of the resonator.

First claim

The invention claimed is:

1. A bulk acoustic wave resonator (BAWR) comprising:
an electro-acoustically active region with two electrodes and a piezoelectric layer arranged between them;
a support substrate;
an acoustic mirror arranged between the electro-acoustically active region and the support substrate and comprising a layer of low thermal conductivity and a layer of high thermal conductivity; and
a thermal bridge coupled to the support substrate and the electro-acoustically active region;
wherein the layer of low thermal conductivity is suitable for reducing a heat flow from the electro-acoustically active region to the support substrate, and
wherein the thermal bridge is provided to increase the heat flow from the electro-acoustically active region to the support substrate.

2. The BAWR according to claim 1 , wherein the acoustic mirror comprises layers of low thermal conductivity and layers of high thermal conductivity.

3. The BAWR according to claim 2 , wherein the layers of low thermal conductivity have a low acoustic impedance and the layers of high thermal conductivity have a high acoustic impedance.

4. The BAWR according to claim 2 , wherein the layers of low thermal conductivity comprise a dielectric material and the layers of high thermal conductivity comprise a metal.

5. The BAWR according to claim 1 , wherein the thermal bridge has a higher thermal conductivity than the layer of low thermal conductivity.

6. The BAWR according to claim 1 , wherein:
the distance between the thermal bridge and the active region is smaller than the distance between the electro-acoustically active region and the support substrate, and
the distance between the thermal bridge and the support substrate is smaller than the distance between the electro-acoustically active region and the support substrate.

7. The BAWR according to claim 1 , wherein the thermal bridge comprises a region surrounding the electro-acoustically active region in the lateral direction.

8. The BAWR according to claim 1 , wherein the thermal bridge comprises a region, arranged in at least one layer of low thermal conductivity and connecting at least one layer of high thermal conductivity to the electro-acoustically active region or to the support substrate.

9. The BAWR according to claim 2 , wherein the thermal bridge comprises a region arranged in at least one layer of low thermal conductivity and connecting two layers of high thermal conductivity to each other.

10. A high frequency filter comprising a bulk acoustic wave resonator (BAWR) according to claim 1 .

11. A duplexer comprising a high frequency filter having a bulk acoustic wave resonator (BAWR) according to claim 1 .

12. A method for producing a bulk acoustic wave resonator (BAWR), comprising:
forming an acoustic mirror with alternating layers of high and low thermal conductivity on a support substrate,
forming an electro-acoustically active region with a piezoelectric layer between two electrode layers on the acoustic mirror, and
forming a thermal bridge, which is configured to transfer heat from the electro-acoustically active region to the support substrate, coupled to the support substrate and the electro-acoustically active region.

13. The method according to claim 12 , wherein the thermal bridge comprises a region comprising a material of higher thermal conductivity than the layers of low thermal conductivity and laterally surrounding the electro-acoustically active region.

14. The method according to claim 12 , wherein the thermal bridge comprises a region comprising a material of higher thermal conductivity than the layers of low thermal conductivity and being structured within the layers of low thermal conductivity.

15. The method according to claim 14 , wherein forming the thermal bridge comprises depositing, via lithography processes, material of the thermal bridge in the layers of low thermal conductivity.

Assignees

• Snaptrack Inc

Inventors

• Tag Andreas
• Bader Bernhard
• Pitschi Maximilian

Classifications

• H03H9/175 Primary

  Acoustic mirrors · CPC title

• H03H9/02102 Primary

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

• H03H9/706

  Duplexers · CPC title

• H01L41/27

  Electricity · mapped topic

• H10N30/05

  Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes · CPC title