CN217693270U - Acoustic wave resonator, filter, and communication apparatus - Google Patents

Abstract

The embodiment of the utility model provides an acoustic wave syntonizer, wave filter and communication equipment, wherein the acoustic wave syntonizer includes: the substrate is provided with a cavity; a bottom electrode disposed on the substrate and covering the cavity; at least one raised structure disposed within and raised towards the substrate, the raised structure being disposed around a periphery of the cavity; a piezoelectric layer disposed on the bottom electrode; a top electrode disposed on the piezoelectric layer.

Description

Acoustic wave resonator, filter, and communication apparatus

Technical Field

The utility model relates to a semiconductor device technical field, concretely relates to sound wave syntonizer, wave filter and communication equipment.

Background

Acoustic resonators, such as Film Bulk Acoustic Resonators (FBAR), currently play an important role in the fields of communications, sensors, and the like. The high-sensitivity radio frequency filter has the advantages of small volume, high frequency, large power capacity and the like, so that the high-sensitivity radio frequency filter occupies a larger and larger share in the field of radio frequency front ends, particularly in the market of radio frequency filters, and has great development advantages in the fields of biosensing, medical measurement and the like.

The bulk acoustic wave resonator has a main structure of a sandwich structure consisting of a bottom electrode, a piezoelectric film and a top electrode, applies an electric signal between the electrodes, converts an input electric signal into acoustic vibration by utilizing an inverse piezoelectric effect, converts the acoustic vibration into the electric signal by utilizing the piezoelectric effect, and outputs the electric signal. Due to the existence of the transverse mode, a part of the transverse sound wave leaks out from the edge of the electrode, so that the sound wave energy in the sound wave resonator is reduced, and the Q value of the resonator is reduced.

SUMMERY OF THE UTILITY MODEL

In view of this, the embodiment of the present invention provides an acoustic wave resonator, a filter and a communication device, so as to solve the problem that the Q value of the resonator is reduced due to the leakage of the lateral acoustic wave of the existing acoustic wave resonator.

To this end, according to a first aspect, an embodiment of the present invention provides an acoustic wave resonator, including:

the substrate is provided with a cavity;

a bottom electrode disposed on the substrate and covering the cavity;

at least one protruding structure arranged in the substrate and protruding towards the inside of the substrate, wherein the protruding structure is arranged around the periphery of the cavity;

a piezoelectric layer disposed on the bottom electrode;

a top electrode disposed on the piezoelectric layer.

Optionally, the raised structure is formed below and in contact with the bottom electrode and/or the piezoelectric layer.

Optionally, a projection of the protruding structure on the plane where the substrate is located is a circle, an ellipse, or a polygon.

Optionally, the raised structure is made of a high acoustic impedance material.

Optionally, the protruding structures are multiple, and the multiple protruding structures are all arranged around the periphery of the cavity, and

a plurality of the convex structures are arranged at intervals; or alternatively

A plurality of the convex structures are arranged in contact with each other.

Optionally, the height of the protrusion structure protruding into the substrate at the outer side is greater than the height of the protrusion structure protruding into the substrate at the inner side.

Optionally, the protruding structure at the innermost side is 1-6 μm away from the cavity, and the height of the protruding structure at the innermost side is 0.04-0.3 μm and the width is 1-8 μm.

Optionally, the height of the protruding structure located at the outermost side is 0.06-0.4 μm, and the width is 1-12 μm.

According to a second aspect, embodiments of the present invention provide a filter comprising at least one acoustic wave resonator according to any one of the above first aspects.

According to a third aspect, embodiments of the present invention provide a communication device, including the filter of the second aspect.

According to the utility model discloses acoustic wave syntonizer, wave filter and communication equipment, protruding structure encircles the periphery setting of cavity to can be in the outside reflection horizontal sound wave of cavity, restraint sound wave energy promotes the Q value of syntonizer, protruding structure forms in the base plate and outside being located the effective resonance area of acoustic wave syntonizer simultaneously, can not produce the mass load, and reduced the influence to the effective electromechanical coupling coefficient of acoustic wave syntonizer by a wide margin.

Drawings

The features and advantages of the invention will be more clearly understood by reference to the accompanying drawings, which are schematic and are not to be understood as imposing any limitation on the invention, and in which:

FIG. 1 shows a schematic diagram of a prior art acoustic wave resonator;

fig. 2A and 2B show schematic diagrams of acoustic wave resonators according to embodiments of the present invention;

fig. 3 shows frequency-impedance plots of an acoustic wave resonator of an embodiment of the present invention versus a prior art acoustic wave resonator;

fig. 4A and 4B show schematic views of an acoustic wave resonator according to another embodiment of the present invention;

fig. 5A and 5B show schematic diagrams of an acoustic wave resonator according to still another embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

In order to solve the problem that the transverse sound wave of the acoustic wave resonator leaks from the edge of the electrode, the acoustic wave resonator is provided in the prior art, as shown in fig. 1, a sandwich structure consisting of a bottom electrode 13, a piezoelectric layer 14 and a top electrode 15 is formed on a substrate 11 with a cavity 12, a protruding structure 16 is formed on the top electrode 15, and the protruding structure 16 is located at the edge of the top electrode 15, so that the transverse sound wave can be reflected at the edge of the acoustic wave resonator, and the Q value of the resonator is further improved. However, the raised structure 16 is inherently massive and can cause a certain mass loading on the piezoelectric layer 14, resulting in a frequency shift of the acoustic wave resonator, and the raised structure 16 located in the resonance region can also reduce the effective electromechanical coupling coefficient of the acoustic wave resonator, thereby reducing the filter bandwidth.

Fig. 2A and 2B show an acoustic wave resonator according to an embodiment of the present invention, in which fig. 2A isbase:Sub>A top view of the acoustic wave resonator of the present embodiment on the upper surface ofbase:Sub>A substrate, and fig. 2B isbase:Sub>A cross-sectional view along linebase:Sub>A-base:Sub>A in fig. 2A, as shown in fig. 2A and 2B, the acoustic wave resonator according to an embodiment of the present invention may includebase:Sub>A substrate 21, and the substrate 21 may bebase:Sub>A substrate or an epitaxial layer formed onbase:Sub>A substrate, and the substrate may be formed ofbase:Sub>A material compatible with the semiconductor process, such as silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), glass, sapphire, alumina, siC, or the like. The cavity 22 is formed in the substrate 21, and in the example of fig. 2A, the projection of the cavity 22 on the plane where the substrate 21 is located is a regular octagon, but those skilled in the art should understand that the projection shape of the cavity 22 on the plane where the substrate 21 is located is not limited thereto, and may be any regular pattern such as a polygon, a circle, or an ellipse, or may be an irregular pattern.

The acoustic wave resonator of the embodiment of the present invention is formed with the bottom electrode 23 on the substrate 21, and the bottom electrode covers the cavity 22, and the piezoelectric layer 24 is formed on the bottom electrode 23, in the example of fig. 2B, the piezoelectric layer 24 extends and covers the bottom electrode 23, the cavity 22 and the substrate 21, and those skilled in the art should understand that the piezoelectric layer 24 may also be formed only on the bottom electrode 23. A top electrode 25 is formed on the piezoelectric layer 24. The bottom electrode 23 and the top electrode 25 may be a single layer or a multi-layer, and the bottom electrode or the top electrode may be formed of one or more conductive materials, for example, various metals compatible with a semiconductor process including tungsten (W), molybdenum (Mo), iridium (Ir), aluminum (Al), platinum (Pt), ruthenium (Ru), niobium (Nb), or hafnium (Hf). The bottom and top electrodes may be of the same or different materials. The piezoelectric layer 24 may be formed of any piezoelectric material compatible with semiconductor processing, such as aluminum nitride (AlN), doped aluminum nitride (AlN), or zirconate titanate (PZT). The overlapped part of the top electrode, the piezoelectric layer and the bottom electrode above the acoustic wave reflection area forms a sandwich structure of the acoustic wave resonator.

Further, a mass loading layer may be formed on the top electrode 25, and a protective layer may be formed on the mass loading layer to protect the acoustic wave resonator. It should be understood by those skilled in the art that a bonding layer and a cover plate (cap wafer) may also be formed on the acoustic wave resonator, and the bonding layer and the cover plate are bonded and thinned to form a device package, where the bonding layer material may be, for example, au, or other suitable bonding materials, and will not be described herein again.

In fig. 2A and 2B, the acoustic wave resonator of the embodiment of the present invention further includes a protruding structure 26, the protruding structure 26 is disposed in the substrate 21 and protrudes toward the substrate 21, and the protruding structure 26 is disposed around the periphery of the cavity 22. Only one raised structure 26 is shown in the example of fig. 2A and 2B, it being understood by those skilled in the art that multiple raised structures are also possible. Furthermore, in the example of fig. 2A and 2B, the projection of the protruding structure 26 on the plane where the substrate 21 is located is a circle, however, the present invention is not limited thereto, and those skilled in the art can adaptively adjust the projection shape of the protruding structure 26 on the plane where the substrate 21 is located according to the shape of the cavity 22, and the projection shape of the protruding structure 26 on the plane where the substrate 21 is located can be any regular figure, such as various circles, ellipses or polygons, and even any irregular figure, as long as it is disposed around the periphery of the cavity 22, that is, it can reflect the transverse sound wave outside the cavity to restrain the sound wave energy. As an alternative to the embodiments of the present invention, the protruding structure is made of high acoustic impedance material, such as metal Mo, W, pt, etc., so as to better reflect the transverse sound wave. In the acoustic wave resonator according to the embodiment of the present invention, the material used for the protruding structure 26 may be the same as or different from the material used for the bottom electrode 23. When the material of the protruding structure 26 is the same as the material of the bottom electrode 23, a deposition process may be used to form the protruding structure 26 and the bottom electrode metal layer, and then the bottom electrode metal layer is etched to form the bottom electrode 23.

Fig. 3 shows frequency-impedance graphs of the acoustic wave resonator having the bump structure as shown in fig. 2A and 2B, and the acoustic wave resonator not having the bump structure, in which the height of the bump structure is 0.22 μm and the width is 2 μm, and other parameters are the same as those of the acoustic wave resonator not having the bump structure. As shown in fig. 3, contain protruding structure the utility model discloses an acoustic wave syntonizer compares with the acoustic wave syntonizer that does not contain protruding structure, and the impedance of parallel resonance point department has promoted 35%, and parallel resonance point frequency deviation is less, has hardly influenced effective electromechanical coupling coefficient.

Therefore, the utility model discloses acoustic resonator's protruding structure encircles the periphery setting of cavity to can be in the outside reflection horizontal sound wave of cavity, restraint sound wave energy promotes the Q value of syntonizer, protruding structure forms in the base plate and outside being located acoustic resonator's effective resonance area simultaneously, can not produce the mass load, and reduced the influence to acoustic resonator's effective electromechanical coupling coefficient by a wide margin.

In the example of fig. 2B, the raised structure 26 is formed below the piezoelectric layer 24 and in contact with the piezoelectric layer 24. In the example of fig. 4B, the convex structure 26 is plural, a part of the convex structure 26 is formed under the bottom electrode 23, and a part of the convex structure 26 is formed under the piezoelectric layer 24 and is in contact with the bottom electrode 23 and the piezoelectric layer 24. In the example of fig. 5A, the convex structure 26 is formed under the bottom electrode 23 and is in contact with the bottom electrode 23.

Fig. 4A and 4B are schematic diagrams showing an acoustic wave resonator according to another embodiment of the present invention, fig. 4A is a plan view of the acoustic wave resonator of the present embodiment on the upper surface of the substrate, and fig. 4B is a cross-sectional view taken along line B-B in fig. 4A. While 3 raised structures 26 are provided in fig. 4A and 4B, those skilled in the art will appreciate that fig. 4A and 4B are merely exemplary and that raised structures 26 may include fewer or more raised structures. In the example of fig. 4A and 4B, the raised structures 26 are spaced apart from one another, but those skilled in the art will appreciate that the raised structures may also be in contact with one another. As shown in fig. 4A, the plurality of protruding structures 26 are all disposed around the periphery of the cavity 22, in the example of fig. 4A, the plurality of protruding structures 26 are circular structures disposed concentrically, and it should be understood by those skilled in the art that the projection shape of the protruding structures 26 on the plane where the substrate 21 is located may be any regular pattern, such as various circles, ellipses or polygons, and may even be any irregular pattern, as long as they are disposed around the periphery of the cavity 22, and the concentric arrangement between the protruding structures 26 does not need to be maintained. In the embodiment shown in fig. 4A and 4B, because a plurality of protruding structures 26 are adopted, the lateral acoustic wave can be better reflected at the outer side of the cavity, the acoustic wave energy is confined, and the Q value of the resonator is further improved.

Fig. 5A and 5B are schematic diagrams showing an acoustic wave resonator according to another embodiment of the present invention, in which fig. 5B shows a portion inside a dotted line frame in fig. 5A. Unlike the acoustic wave resonators shown in fig. 4A and 4B in which the respective bump structures are arranged at intervals and the heights thereof are kept uniform, the plurality of bump structures of the acoustic wave resonators shown in fig. 5A and 5B are arranged in contact with each other and the heights of the respective bump structures are different, thereby constituting one stepped bump structure. More specifically, as shown in fig. 5B, three protruding structures 261, 262, 263 are disposed in contact with each other to form a stepped protruding structure 26. It will be understood by those skilled in the art that fig. 5A and 5B are merely exemplary, and that the raised structures 26 may be provided by fewer or more raised structures in contact with each other.

Further, as shown in fig. 5B, the heights of the protruding structures 261, 262, and 263 gradually increase from inside to outside, that is, the height of the protruding structure at the outside protruding toward the inside of the substrate is greater than the height of the protruding structure at the inside protruding toward the inside of the substrate. Compared with the embodiment shown in fig. 4A and 4B, the acoustic wave resonator adopting the convex structure with the gradually increasing height from inside to outside can better reflect transverse acoustic waves, restrain acoustic wave energy and further improve the Q value of the resonator. It should be understood by those skilled in the art that, in order to further raise the Q value of the resonator, those skilled in the art may also set the protruding structures 26 in the embodiments shown in fig. 4A and 4B to have gradually increasing heights from inside to outside, that is, the protruding structures on the outer side protrude toward the inside of the substrate by a greater height than the protruding structures on the inner side protrude toward the inside of the substrate, so as to further raise the Q value of the resonator.

More specifically, as shown in FIG. 5B, the distance d of the innermost protruding structure 261 from the cavity 22 is 1 to 6 μm, and the height h1 of the innermost protruding structure 261 is 0.04 to 0.3 μm and the width w1 is 1 to 8 μm. Further, the height h2 of the convex structure positioned at the outermost side is 0.06-0.4 μm, and the width w2 is 1-12 μm.

The embodiment of the present invention further provides a filter, which may include at least one acoustic wave resonator as described in any of the embodiments shown in fig. 2A to 5B above.

The details of the filter can be understood by referring to the corresponding related descriptions and effects in the embodiments shown in fig. 2A to fig. 5B, which are not described herein again.

Embodiments of the present invention further provide a communication device, such as a portable communication device, for example, a mobile phone, a Personal Digital Assistant (PDA), an electronic game device, and the like, which may include the filter described above.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims (10)

1. An acoustic wave resonator, comprising:

the substrate is provided with a cavity;

a bottom electrode disposed on the substrate and covering the cavity;

at least one protruding structure arranged in the substrate and protruding towards the inside of the substrate, wherein the protruding structure is arranged around the periphery of the cavity;

a piezoelectric layer disposed on the bottom electrode;

a top electrode disposed on the piezoelectric layer.

2. The acoustic resonator according to claim 1, wherein the raised structure is formed below and in contact with the bottom electrode and/or the piezoelectric layer.

3. The acoustic resonator according to claim 1, wherein a projection of the convex structure on a plane on which the substrate is located is circular, elliptical or polygonal.

4. The acoustic resonator of claim 1, wherein the raised structure is made of a high acoustic impedance material.

5. The acoustic resonator according to any one of claims 1 to 4, wherein the projection structure is plural, plural projection structures are each provided around the periphery of the cavity, and

a plurality of the convex structures are arranged at intervals; or alternatively

A plurality of the convex structures are arranged in contact with each other.

6. The acoustic resonator according to claim 5, wherein the height of the convex structure at the outer side that protrudes toward the inside of the substrate is larger than the height of the convex structure at the inner side that protrudes toward the inside of the substrate.

7. The acoustic resonator according to claim 5, wherein the convex structure located innermost is 1 to 6 μm from the cavity, and the convex structure located innermost has a height of 0.04 to 0.3 μm and a width of 1 to 8 μm.

8. The acoustic resonator according to claim 5, wherein the height of the convex structure located on the outermost side is 0.06-0.4 μm, and the width is 1-12 μm.

9. A filter comprising at least one acoustic wave resonator according to any one of claims 1 to 8.

10. A communication device comprising the filter of claim 9.

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