CN112865742A - Bulk acoustic wave resonator - Google Patents

Bulk acoustic wave resonator Download PDF

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Publication number
CN112865742A
CN112865742A CN201911100619.9A CN201911100619A CN112865742A CN 112865742 A CN112865742 A CN 112865742A CN 201911100619 A CN201911100619 A CN 201911100619A CN 112865742 A CN112865742 A CN 112865742A
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China
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bulk acoustic
acoustic wave
wave resonator
piezoelectric layer
lower electrode
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CN201911100619.9A
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Chinese (zh)
Inventor
缪建民
张瑞珍
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Sv Senstech Wuxi Co ltd
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Maigan Microelectronics Shanghai Co ltd
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    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03HIMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/178Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator of a laminated structure of multiple piezoelectric layers with inner electrodes

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

The embodiment of the invention discloses a bulk acoustic wave resonator. The bulk acoustic wave resonator includes: an upper electrode, a piezoelectric layer, and a lower electrode, the piezoelectric layer being disposed between the upper electrode and the lower electrode; at least part of the boundary of the vertical projection of the piezoelectric layer on the lower electrode comprises a plurality of saw-tooth structures. The side surface of the piezoelectric layer is provided with the plurality of sawtooth structures, so that the side surface of the piezoelectric layer forms irregular edges, when transverse bulk acoustic waves generated after the piezoelectric layer is electrified are transmitted to the surface of the piezoelectric layer, which is in contact with air, disordered reflection or diffuse reflection can be generated, and transverse standing waves are prevented from being formed. The technical scheme of the embodiment of the invention solves the problems that the existing bulk acoustic wave resonator can generate standing waves in other forms besides longitudinal bulk acoustic waves, increases the noise of the bulk acoustic wave resonator and has adverse effect on the performance of the bulk acoustic wave resonator, prevents standing waves in other forms from being generated, reduces the noise of the bulk acoustic wave resonator and improves the performance of the bulk acoustic wave resonator.

Description

Bulk acoustic wave resonator
Technical Field
The embodiment of the invention relates to the technical field of resonators, in particular to a bulk acoustic wave resonator.
Background
The ideal bulk acoustic wave resonator is an acoustic stack consisting of an upper electrode, a piezoelectric layer and a lower electrode, and has the advantages of small size, good performance, suitability for integrated circuits and the like.
The bulk acoustic wave resonator generally excites a longitudinal bulk acoustic wave propagating in the thickness direction of the piezoelectric layer, which is a major factor affecting the quality of the bulk acoustic wave resonator. However, in addition to generating the desired longitudinal bulk acoustic wave, the existing bulk acoustic wave resonators often generate other forms of standing waves in the device, which increases the noise of the bulk acoustic wave resonators and adversely affects the performance of the bulk acoustic wave resonators.
Disclosure of Invention
The invention provides a bulk acoustic wave resonator, which is used for preventing standing waves in other forms from being generated, reducing the noise of the bulk acoustic wave resonator and improving the performance of the bulk acoustic wave resonator.
In a first aspect, an embodiment of the present invention provides a bulk acoustic wave resonator, including:
an upper electrode, a piezoelectric layer, and a lower electrode, the piezoelectric layer being disposed between the upper electrode and the lower electrode;
at least part of the boundary of the vertical projection of the piezoelectric layer on the lower electrode comprises a plurality of sawtooth structures.
Optionally, at least a partial boundary of a vertical projection of the upper electrode and the lower electrode on a plane perpendicular to a thickness direction of the bulk acoustic wave resonator includes a plurality of saw-tooth structures.
Optionally, the center-to-center spacing between adjacent saw tooth structures is greater than or equal to 2 microns.
Optionally, all boundaries of the vertical projection of the piezoelectric layer on the lower electrode comprise a plurality of saw-tooth structures.
Optionally, a plurality of said sawtooth structures are end-to-end in sequence on said boundary.
Optionally, the shape of the sawtooth structure comprises a triangle or a trapezoid.
Optionally, a shape of a perpendicular projection of the bulk acoustic wave resonator on a plane perpendicular to a thickness direction thereof includes a polygon.
Optionally, the material of the upper electrode and the lower electrode is any one of gold, molybdenum, aluminum, chromium, and nickel.
Optionally, the piezoelectric layer is made of any one of lead zirconate titanate piezoelectric ceramic, zinc oxide and aluminum nitride.
An embodiment of the present invention provides a bulk acoustic wave resonator, including: an upper electrode, a piezoelectric layer, and a lower electrode, the piezoelectric layer being disposed between the upper electrode and the lower electrode; at least part of the boundary of the vertical projection of the piezoelectric layer on the lower electrode comprises a plurality of saw-tooth structures. Through set up a plurality of sawtooth structures in the side of piezoelectric layer, make the side of piezoelectric layer form irregular edge, when making the horizontal bulk acoustic wave that produces behind the piezoelectric layer circular telegram propagate piezoelectric layer and air contact's surface, can take place indiscriminate reflection or diffuse reflection, prevent the formation of horizontal standing wave, solved current bulk acoustic wave resonator except producing vertical bulk acoustic wave, still can produce the standing wave of other forms, increase the noise of bulk acoustic wave resonator, produce the problem of adverse effect to the performance of bulk acoustic wave resonator, the standing wave of other forms has been stopped and has been produced, the noise of bulk acoustic wave resonator has been reduced, the performance of bulk acoustic wave resonator has been promoted.
Drawings
Fig. 1 is a schematic plan view of a bulk acoustic wave resonator according to an embodiment of the present invention;
fig. 2 is a schematic perspective view of a bulk acoustic wave resonator according to an embodiment of the present invention;
fig. 3 is a schematic vertical projection diagram of a bulk acoustic wave resonator according to an embodiment of the present invention;
fig. 4 is a schematic plan view of a bulk acoustic wave resonator in the prior art;
fig. 5 is a schematic perspective view of another bulk acoustic wave resonator according to an embodiment of the present invention;
FIG. 6 is a graphical representation of impedance as a function of frequency for a bulk acoustic wave resonator in accordance with an embodiment of the present invention;
figures 7-15 are schematic vertical projections of another bulk acoustic wave resonator provided by embodiments of the present invention;
figure 16 is a graphical representation of the impedance as a function of frequency for another bulk acoustic wave resonator provided by an embodiment of the present invention;
fig. 17-18 are schematic vertical projection views of another bulk acoustic wave resonator provided by an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic plan view of a bulk acoustic wave resonator according to an embodiment of the present invention, specifically illustrating a side view of the bulk acoustic wave resonator; fig. 2 is a schematic perspective view of a bulk acoustic wave resonator according to an embodiment of the present invention, specifically illustrating a side-view perspective structure of the bulk acoustic wave resonator; fig. 3 is a schematic vertical projection diagram of a bulk acoustic wave resonator provided by an embodiment of the present invention, and fig. 3 schematically illustrates a shape of a vertical projection of a piezoelectric layer 2 on a lower electrode 3 in the bulk acoustic wave resonator shown in fig. 1-2. As shown in fig. 1 to 3, the bulk acoustic wave resonator includes: an upper electrode 1, a piezoelectric layer 2 and a lower electrode 3, the piezoelectric layer 2 being disposed between the upper electrode 1 and the lower electrode 3; at least part of the boundary of the piezoelectric layer 2 in the vertical projection of the lower electrode 3 comprises a plurality of saw-tooth structures a.
As shown in fig. 1-2, the bulk acoustic wave resonator provided in this embodiment may use a piezoelectric effect based on a bulk acoustic wave resonance technology, and convert an electric energy signal into a corresponding acoustic wave signal after being connected to an external power source, thereby forming resonance. Specifically, the upper electrode 1 can be connected to one pole of an external power supply, the lower electrode 3 can be connected to the other pole of the external power supply, the piezoelectric layer 2 can be correspondingly expanded or contracted along with the change of an electric field generated by the external power supply after being electrified, so that longitudinal bulk acoustic waves are generated in the thickness direction of the piezoelectric layer 2, and the longitudinal bulk acoustic waves can be reflected when being transmitted to the boundary between the upper electrode 1 and air and the boundary between the lower electrode 3 and air, so that oscillation is formed in the piezoelectric layer 2.
As shown in fig. 1 to 3, the side surface of the piezoelectric layer 2 in the thickness direction ao may be provided with a plurality of saw-tooth structures, so that the side surface of the piezoelectric layer 2 forms an irregular edge, and when the piezoelectric layer 2 is vertically projected to the lower electrode 3 in the thickness direction ao, the vertical projection on the surface of the lower electrode 3 takes a shape in which at least a part of the boundary conforming to the shape of the side surface edge of the piezoelectric layer 2 includes the plurality of saw-tooth structures a.
Fig. 4 is a schematic plan view of a bulk acoustic wave resonator in the prior art, and particularly shows a side plan view of the bulk acoustic wave resonator in the prior art. As shown in fig. 4, the piezoelectric layer 2 'of the bulk acoustic wave resonator in the prior art is consistent with the size and shape of the upper electrode 1' and the lower electrode 3 ', and the side surface of the piezoelectric layer 2' presents a regular planar structure, and all edges are straight lines. However, after the bulk acoustic wave resonator in the prior art is connected to an external power supply, the piezoelectric layer 2' may generate a transverse bulk acoustic wave in addition to a desired longitudinal bulk acoustic wave, so that after standing, noise of the bulk acoustic wave resonator may be increased, and performance of the bulk acoustic wave resonator may be reduced.
The bulk acoustic wave resonator provided by the embodiment includes: an upper electrode, a piezoelectric layer, and a lower electrode, the piezoelectric layer being disposed between the upper electrode and the lower electrode; at least part of the boundary of the vertical projection of the piezoelectric layer on the lower electrode comprises a plurality of saw-tooth structures. Through set up a plurality of sawtooth structures in the side of piezoelectric layer, make the side of piezoelectric layer form irregular edge, when making the horizontal bulk acoustic wave that produces behind the piezoelectric layer circular telegram propagate piezoelectric layer and air contact's surface, can take place indiscriminate reflection or diffuse reflection, prevent the formation of horizontal standing wave, solved current bulk acoustic wave resonator except producing vertical bulk acoustic wave, still can produce the standing wave of other forms, increase the noise of bulk acoustic wave resonator, produce the problem of adverse effect to the performance of bulk acoustic wave resonator, the standing wave of other forms has been stopped and has been produced, the noise of bulk acoustic wave resonator has been reduced, the performance of bulk acoustic wave resonator has been promoted.
Fig. 5 is a schematic perspective view of another bulk acoustic wave resonator according to an embodiment of the present invention. As shown in fig. 5, optionally, on the basis of the above technical solution, at least part of the boundary of the vertical projection of the upper electrode 1 and the lower electrode 3 on the plane perpendicular to the thickness direction of the bulk acoustic wave resonator includes a plurality of saw-tooth structures a.
Specifically, referring to fig. 5, a plurality of saw-tooth structures a may be provided on the side surfaces of the upper electrode 1, the piezoelectric layer 2, and the lower electrode 3, so that the side surfaces of the upper electrode 1, the piezoelectric layer 2, and the lower electrode 3 each form an irregular edge, and when the upper electrode 1, the piezoelectric layer 2, and the lower electrode 3 are vertically projected in the thickness direction ao of the bulk acoustic wave resonator, the vertical projection presents a shape in which at least part of the boundary that coincides with the shape of the side edge of the upper electrode 1, the piezoelectric layer 2, and the lower electrode 3 includes the plurality of saw-tooth structures a (the specific shape of the vertical projection may refer to fig. 3). Therefore, when the bulk acoustic wave resonator is connected with an external power supply, when other directions except the longitudinal bulk acoustic wave generated in the piezoelectric layer 2, such as a transverse bulk acoustic wave, are transmitted in the piezoelectric layer 2, the surfaces of the plurality of zigzag side surfaces, which are in contact with air, transmitted to the upper electrode 1, the piezoelectric layer 2 and the lower electrode 3 can be subjected to more disorderly reflection or diffuse reflection, so that the formation of transverse standing waves or standing waves in other directions is prevented, the noise of the bulk acoustic wave resonator is further reduced, and the performance of the bulk acoustic wave resonator is improved.
It should be noted that fig. 5 schematically illustrates a case where shapes of the upper electrode 1, the piezoelectric layer 2, and the lower electrode 3 are the same, and in practical applications, shapes of the upper electrode 1, the piezoelectric layer 2, and the lower electrode 3 may be the same or different, so as to ensure that the upper electrode 1, the piezoelectric layer 2, and the lower electrode 3 can form saw-tooth-shaped side surfaces, respectively.
Fig. 6 is a graph illustrating impedance and frequency of a bulk acoustic wave resonator according to an embodiment of the present invention. As shown in fig. 6, a curve C shown by a dotted line is a function curve between the impedance and the frequency of the bulk acoustic wave resonator in the prior art provided in fig. 4, and a curve D is a function curve between the impedance and the frequency of the bulk acoustic wave resonator provided in the embodiment of the present invention shown in fig. 5.
Referring to fig. 3, optionally, on the basis of the above technical solution, all boundaries of the vertical projection of the piezoelectric layer on the lower electrode include a plurality of saw-tooth structures a. Exemplarily, when the saw-tooth structure a is provided only on the side of the piezoelectric layer, all sides of the piezoelectric layer may be provided with a plurality of saw-tooth structures a, and accordingly, all boundaries of the vertical projection of the piezoelectric layer on the lower electrode include a plurality of saw-tooth structures a; when the side surfaces of the upper electrode, the piezoelectric layer and the lower electrode are all provided with the sawtooth structures a, all the side surfaces of the upper electrode, the piezoelectric layer and the lower electrode can be provided with a plurality of sawtooth structures a, and accordingly, when the upper electrode, the piezoelectric layer and the lower electrode are vertically projected in the thickness direction of the bulk acoustic wave resonator, all boundaries of the vertical projection all include a plurality of sawtooth structures a.
Optionally, on the basis of the above technical solution, a part of a boundary of the vertical projection of the piezoelectric layer on the lower electrode includes a plurality of sawtooth structures, specifically, any one of the boundaries includes a plurality of sawtooth structures, any two of the boundaries includes a plurality of sawtooth structures, or any three of the boundaries includes a plurality of sawtooth structures. Fig. 7 is a schematic vertical projection view of another bulk acoustic wave resonator provided by an embodiment of the present invention, and fig. 7 schematically shows a case where one boundary of the vertical projection of the piezoelectric layer on the lower electrode includes a plurality of saw-tooth structures a. Fig. 8 is a schematic vertical projection of another bulk acoustic wave resonator provided by an embodiment of the present invention; fig. 9 is a schematic vertical projection view of another bulk acoustic wave resonator provided by an embodiment of the present invention, and fig. 8 to 9 schematically show two cases where two boundaries of the vertical projection of the piezoelectric layer on the lower electrode include a plurality of saw-tooth structures a. Fig. 10 is a schematic vertical projection view of another bulk acoustic wave resonator provided by an embodiment of the present invention, and fig. 10 schematically illustrates a case where three boundaries of a vertical projection of a piezoelectric layer on a lower electrode include a plurality of saw-tooth structures a.
It should be noted that, if the saw-tooth structures are disposed on the side surfaces of the upper electrode, the piezoelectric layer, and the lower electrode of the bulk acoustic wave resonator, and the upper electrode, the piezoelectric layer, and the lower electrode are vertically projected along the thickness direction of the bulk acoustic wave resonator, the shape of the vertical projection can also refer to fig. 3 and fig. 7-10, specifically, the saw-tooth structure a is disposed only on the piezoelectric layer, or the saw-tooth structure a is disposed on the upper electrode, the piezoelectric layer, and the lower electrode, and the arrangement conditions of the saw-tooth structures a on the side surfaces in both cases can be determined by combining practical application conditions.
As shown in fig. 7-10, optionally, on the basis of the above technical solution, a plurality of sawtooth structures a are connected end to end in sequence on the boundary. Specifically, each sawtooth structure a includes two intersecting sides, an intersecting point is a vertex, and non-intersecting points are end points, and a plurality of sawtooth structures a may be arranged to be sequentially connected end to end through the end points, so that a plurality of continuous sawtooth structures a are formed on the side surface of the piezoelectric layer, or the side surfaces of the upper electrode, the piezoelectric layer, and the lower electrode, and a plurality of sawtooth structures a sequentially connected end to end are also included on the corresponding vertical projection boundary.
Fig. 11 is a schematic vertical projection of another bulk acoustic wave resonator according to an embodiment of the present invention. As shown in fig. 11, alternatively, on the basis of the above technical solution, a plurality of saw-tooth structures a with set intervals may be disposed on the side surface of the piezoelectric layer, or the side surfaces of the upper electrode, the piezoelectric layer and the lower electrode, and a plurality of discontinuous saw-tooth structures a may be formed on the corresponding boundaries of the vertical projection.
As shown in fig. 7 to 11, optionally, on the basis of the above technical solution, the shapes of the plurality of sawtooth structures a are the same. By the arrangement, the process difficulty in the manufacture of the sawtooth structure can be reduced, and the process cost is reduced.
Fig. 12 is a schematic vertical projection of another bulk acoustic wave resonator according to an embodiment of the present invention. As shown in fig. 12, optionally, on the basis of the above technical solution, the shapes of the plurality of saw-tooth structures may also be different. Specifically, a plurality of saw tooth structures with the same shape may be provided on the side surface of the piezoelectric layer, or the side surfaces of the upper electrode, the piezoelectric layer, and the lower electrode, or a plurality of saw tooth structures with different shapes may be provided, and the saw tooth structures may be specifically set in combination with the effect of preventing the standing wave in other forms except for the longitudinal bulk acoustic wave from being generated by the saw tooth structures and the practical application situation.
In addition, the sizes of the plurality of sawtooth structures can be the same or different, and the sawtooth structures can be specifically arranged according to requirements.
Optionally, on the basis of the above technical solution, the shape of the sawtooth structure includes a triangle or a trapezoid. By the arrangement, the process of the sawtooth structure is simple during manufacturing, and the process cost is reduced. Fig. 13 is a schematic vertical projection of another bulk acoustic wave resonator according to an embodiment of the present invention. Fig. 2 to 3, fig. 5, and fig. 7 to 12 show the case where the saw-tooth structure is triangular, and fig. 13 shows the case where the saw-tooth structure a' is trapezoidal, and the specific shape of the saw-tooth structure can be selected in combination with the practical application and the effect of the saw-tooth structure on preventing the generation of standing waves of other forms than longitudinal bulk acoustic waves.
Referring to fig. 11, alternatively, on the basis of the above technical solution, the center-to-center distance B between adjacent sawtooth structures a is greater than or equal to 2 micrometers. By the arrangement, the manufacturing process difficulty of the sawtooth structure A is further reduced, and the manufacturing cost is reduced.
Fig. 14 is a schematic vertical projection of another bulk acoustic wave resonator provided by an embodiment of the present invention; fig. 15 is a schematic vertical projection of another bulk acoustic wave resonator according to an embodiment of the present invention. Fig. 3 shows that a plurality of sawtooth structures a which are connected in sequence and have the same size are arranged on the side surfaces of the piezoelectric layer along the thickness direction, and the center distance B between adjacent sawtooth structures a is the same size, and fig. 14 to 15 show that a plurality of sawtooth structures a which are connected in sequence and have the same size are arranged on the side surfaces of the piezoelectric layer along the thickness direction, and the center distances B between adjacent sawtooth structures a are the sparse size and the encrypted size respectively. Figure 16 is a graphical representation of the impedance as a function of frequency for another bulk acoustic wave resonator provided by an embodiment of the present invention. Curve G is the curve as a function of impedance and frequency for the bulk acoustic wave resonator corresponding to fig. 3, and curves E and F are the curves as a function of impedance and frequency for the bulk acoustic wave resonators corresponding to fig. 14 and 15, respectively. As shown in fig. 16, the smoothness of the curve E, the curve G and the curve F increases in sequence, and the center-to-center distance B between adjacent saw-tooth structures a in each corresponding bulk acoustic wave resonator decreases in sequence, so that the smaller the center-to-center distance B is, the smoother the function curve of the impedance and the frequency of the bulk acoustic wave resonator is, the less the noise of the bulk acoustic wave resonator is, and the better the performance of the bulk acoustic wave resonator is. Therefore, the more densely the plurality of saw-tooth structures a are arranged on the side faces of the piezoelectric layer, or the side faces of the upper electrode, the piezoelectric layer, and the lower electrode, the better the effect of blocking standing waves of other forms is. Illustratively, the center-to-center spacing B of adjacent sawtooth structures A can be set to an encrypted size in the range of 2um-5um, or a generic size in the range of 5um-10um, or a sparse size in the range of 10um-20 um.
Fig. 17 is a schematic vertical projection of another bulk acoustic wave resonator provided by an embodiment of the present invention; fig. 18 is a schematic vertical projection of another bulk acoustic wave resonator according to an embodiment of the present invention. Optionally, on the basis of the above technical solution, a shape of a vertical projection of the bulk acoustic wave resonator on a plane perpendicular to a thickness direction thereof includes a polygon. Specifically, the shape of the vertical projection of the bulk acoustic wave resonator on the plane perpendicular to the thickness direction of the bulk acoustic wave resonator refers to an approximate shape of the outline of the vertical projection, and the polygon may be a planar figure formed by sequentially connecting three or more line segments end to end, and includes a triangle, a quadrangle, a pentagon and the like, and may be a regular polygon or an irregular polygon, where the quadrangle may be a square or a rectangle. Fig. 3 and 7-15 show the arrangement of saw-tooth structures on a bulk acoustic wave resonator when the external contour of the vertical projection of the bulk acoustic wave resonator on a plane perpendicular to the thickness direction of the bulk acoustic wave resonator is square, and fig. 17-18 show the arrangement of saw-tooth structures on a bulk acoustic wave resonator when the external contour of the vertical projection of the bulk acoustic wave resonator on a plane perpendicular to the thickness direction of the bulk acoustic wave resonator is triangle and quadrangle, respectively. The bulk acoustic wave resonator may have different shapes in combination with its specific structure and application, and the different shapes of the bulk acoustic wave resonator may be provided with saw tooth structures according to any of the embodiments of the present invention.
Alternatively, in addition to the above technical solution, the material of the upper electrode and the lower electrode may be any one of gold, molybdenum, aluminum, chromium, and nickel, or may be another material for manufacturing the upper electrode and the lower electrode. The piezoelectric layer is made of any one of lead zirconate titanate piezoelectric ceramic, zinc oxide and aluminum nitride. Specifically, any one of the above materials can be selected in combination with the structure and application scenario of the bulk acoustic wave resonator and the requirements on the electrical conductivity of the upper electrode, the lower electrode and the piezoelectric layer.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (9)

1. A bulk acoustic wave resonator, comprising:
an upper electrode, a piezoelectric layer, and a lower electrode, the piezoelectric layer being disposed between the upper electrode and the lower electrode;
at least part of the boundary of the vertical projection of the piezoelectric layer on the lower electrode comprises a plurality of sawtooth structures.
2. The bulk acoustic resonator according to claim 1, wherein at least a partial boundary of a perpendicular projection of the upper electrode and the lower electrode on a plane perpendicular to a thickness direction of the bulk acoustic resonator includes a plurality of saw-tooth structures.
3. The bulk acoustic wave resonator according to claim 1, wherein a center-to-center distance between adjacent saw tooth structures is greater than or equal to 2 μm.
4. The bulk acoustic resonator according to claim 1, wherein the piezoelectric layer comprises a plurality of saw-tooth structures at all boundaries of a vertical projection of the lower electrode.
5. The bulk acoustic wave resonator according to claim 4, wherein a plurality of the saw-tooth structures are sequentially connected end to end on the boundary.
6. The bulk acoustic wave resonator according to claim 1, wherein the saw-tooth structure comprises a triangular or trapezoidal shape.
7. The bulk acoustic wave resonator according to claim 1, wherein a shape of a perpendicular projection of the bulk acoustic wave resonator on a plane perpendicular to a thickness direction thereof comprises a polygon.
8. The bulk acoustic wave resonator according to claim 1, wherein the upper electrode and the lower electrode are made of any one of gold, molybdenum, aluminum, chromium, and nickel.
9. The bulk acoustic wave resonator according to claim 1, wherein the piezoelectric layer is made of any one of lead zirconate titanate piezoelectric ceramic, zinc oxide, and aluminum nitride.
CN201911100619.9A 2019-11-12 2019-11-12 Bulk acoustic wave resonator Pending CN112865742A (en)

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CN201911100619.9A CN112865742A (en) 2019-11-12 2019-11-12 Bulk acoustic wave resonator

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CN201911100619.9A CN112865742A (en) 2019-11-12 2019-11-12 Bulk acoustic wave resonator

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CN112865742A true CN112865742A (en) 2021-05-28

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