Film bulk acoustic resonator and fabrication method thereof, filter, and radio frequency communication system

Patent metadata

Field	Value
Publication number	US-12081197-B2
Application number	US-202117198698-A
Country	US
Kind code	B2
Filing date	Mar 11, 2021
Priority date	Jul 19, 2019
Publication date	Sep 3, 2024
Grant date	Sep 3, 2024

Abstract

The present disclosure provides a film bulk acoustic resonator and its fabrication method, a filter, and a radio frequency communication system. The film bulk acoustic resonator includes a first substrate and a support layer disposed on the first substrate, where a cavity is formed in the support layer; a piezoelectric stacked layer covering the cavity, where the piezoelectric stacked layer includes an active resonance region and an inactive resonance region surrounding the active resonance region; and at least two trenches, arranged at a junction of the active resonance region and the inactive resonance region to define a range of the active resonance region. The at least two trenches include a first trench and a second trench; the second trench passes through the second electrode layer and the piezoelectric layer; and the first trench passes the first electrode and the piezoelectric layer and is connected to the cavity.

First claim

What is claimed is:

1. A film bulk acoustic resonator, comprising:
a first substrate and a support layer disposed on the first substrate, wherein a cavity is formed in the support layer;
a piezoelectric stacked layer covering the cavity, wherein the piezoelectric stacked layer includes a first electrode, a piezoelectric layer, and a second electrode which are sequentially disposed on the support layer, and the piezoelectric stacked layer includes an active resonance region above a center of the cavity and an inactive resonance region surrounding the active resonance region; and

at least two trenches, arranged at a junction of the active resonance region and the inactive resonance region to define a range of the active resonance region, wherein the at least two trenches include a first trench and a second trench; the second trench passes through the second electrode layer and the piezoelectric layer; and the first trench passes the first electrode and the piezoelectric layer and is connected to the cavity, wherein:
an angle between a sidewall of the first trench and a plane of the second electrode is an obtuse angle, and an angle between a sidewall of the second trench and a plane of the first electrode is an obtuse angle.

2. The film bulk acoustic resonator according to claim 1 , wherein:
the piezoelectric material layer is made of a material including aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, or a combination thereof.

3. The film bulk acoustic resonator according to claim 1 , wherein:
the support layer is connected to the first substrate by a bonding process.

4. The film bulk acoustic resonator according to claim 3 , wherein:
the bonding process includes a thermocompression bonding process or a dry film bonding process.

5. The film bulk acoustic resonator according to claim 1 , wherein:
a projection of the active resonance region on a plane of the piezoelectric layer is a polygon, and any two sides of the polygon are not in parallel with each other.

6. The film bulk acoustic resonator according to claim 1 , wherein:
the first electrode includes a first electrode adjoining region and a first electrode resonance region; the first electrode resonance region overlaps the active resonance region;
and the first electrode adjoining region is connected to each of the first electrode resonance region and the support layer.

7. The film bulk acoustic resonator according to claim 6 , wherein:
the second electrode includes a second electrode adjoining region and a second electrode resonance region; the second electrode resonance region overlaps the active resonance region; the second electrode adjoining region is connected to each of the second electrode resonance region and the piezoelectric stacked layer on a periphery of the cavity; and projections of the second electrode adjoining region and the first electrode adjoining region on a plane of the piezoelectric layer are not overlapped with each other.

8. The film bulk acoustic resonator according to claim 1 , wherein:
the support layer is made of a material including silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or a combination thereof.

9. A filter, comprising
at least one film bulk acoustic resonator each comprising:
a first substrate and a support layer disposed on the first substrate, wherein a cavity is formed in the support layer;
a piezoelectric stacked layer covering the cavity, wherein the piezoelectric stacked layer includes a first electrode, a piezoelectric layer, and a second electrode which are sequentially disposed on the support layer, and the piezoelectric stacked layer includes an active resonance region above a center of the cavity and an inactive resonance region surrounding the active resonance region; and
at least two trenches, arranged at a junction of the active resonance region and the inactive resonance region to define a range of the active resonance region, wherein the at least two trenches include a first trench and a second trench; the second trench passes through the second electrode layer and the piezoelectric layer; and the first trench passes the first electrode and the piezoelectric layer and is connected to the cavity, wherein:
an angle between a sidewall of the first trench and a plane of the second electrode is an obtuse angle, and an angle between a sidewall of the second trench and a plane of the first electrode is an obtuse angle.

10. A radio frequency communication system, wherein the radio frequency communication system includes at least one filter according to claim 9 .

11. A method for fabricating a film bulk acoustic resonator, comprising:
providing a second substrate and forming a piezoelectric stacked layer-structure on the second substrate, wherein the piezoelectric stacked layer-structure includes a second electrode layer, a piezoelectric layer, and a first electrode layer which are sequentially formed on the second substrate;
forming a support layer on the first electrode layer, wherein an opening is formed in the support layer, exposing a portion of the first electrode layer;
etching the first electrode layer and the piezoelectric layer to form at least one first trench connected to the opening;
providing a first substrate, and bonding the first substrate with the support layer to seal the opening, forming a cavity;
removing the second substrate; and
etching the second electrode layer and the piezoelectric layer to form at least one second trench, wherein projections of the first trench and the second trench on a plane of the piezoelectric layer enclose an active resonance region, wherein:
an angle between a sidewall of the first trench and a plane of the second electrode layer is an obtuse angle, and an angle between a sidewall of the second trench and a plane of the first electrode layer is an obtuse angle.

12. The method according to claim 11 , wherein bonding the first substrate with the support layer to seal the opening includes:
using a thermocompression bonding process or a dry film bonding process to bond the first substrate with the support layer.

13. The method according to claim 11 , wherein etching the first electrode layer and the piezoelectric layer to form the at least one first trench includes:
using a first patterned mask, etching the first electrode layer and the piezoelectric layer to form the at least one first trench.

14. The method according to claim 11 , wherein etching the first electrode layer and the piezoelectric layer to form the at least one first trench further includes:
patterning the first electrode layer to form a first electrode, wherein the first electrode includes a first electrode adjoining region and a first electrode resonance region; the first electrode resonance region overlaps the active resonance region; and the first electrode adjoining region is connected to each of the first electrode resonance region and the support layer.

15. The method according to claim 14 , wherein etching the second electrode layer and the piezoelectric layer to form the at least one second trench includes:
using a second patterned mask, etching the second electrode layer and the piezoelectric layer to form the at least one second trench.

16. The method according to claim 15 , wherein etching the second electrode layer and the piezoelectric layer to form the at least one second trench further includes:
patterning the second electrode layer to form a second electrode, wherein the second electrode includes a second electrode adjoining region and a second ele

Assignees

• Ningbo Semiconductor Int Corp

Inventors

• Sui huan
• Qi Fei
• Yang Guohuang

Classifications

• H03H9/17

  having a single resonator (crystal tuning forks H03H9/21) · CPC title

• H03H9/13

  for networks consisting of piezoelectric or electrostrictive materials (for networks using surface acoustic waves H03H9/145) · CPC title

• H03H9/0504

  for bulk acoustic wave devices · CPC title

• H03H3/02

  for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence) · CPC title

• H03H2003/023

  the resonators or networks being of the membrane type · CPC title