CN217904380U

CN217904380U - Bulk acoustic wave resonator and bulk acoustic wave filter

Info

Publication number: CN217904380U
Application number: CN202222048719.5U
Authority: CN
Inventors: 王矿伟; 赖志国; 杨清华
Original assignee: Suzhou Huntersun Electronics Co Ltd
Current assignee: Suzhou Huntersun Electronics Co Ltd
Priority date: 2022-08-04
Filing date: 2022-08-04
Publication date: 2022-11-25
Anticipated expiration: 2032-08-04

Abstract

The utility model discloses a bulk acoustic wave resonator and a bulk acoustic wave filter, wherein the bulk acoustic wave resonator comprises a substrate and a resonator body, and the substrate is provided with a first surface and a second surface opposite to the first surface; an acoustic reflection structure is arranged in the substrate and comprises a cavity structure or a groove, the cavity structure is positioned on the side of the first surface, and the groove penetrates through the first surface and the second surface; the substrate comprises a substrate body and a plurality of device supporting points which are connected with the substrate body and are arranged at intervals; the resonator body comprises a lamination of a bottom electrode, a first piezoelectric layer and a top electrode in sequence, the bottom electrode is arranged close to the substrate, at least one part of the boundary of the vertical projection of the resonator body on the substrate body is positioned in the acoustic reflection structure, and the device supporting point is used for supporting the resonator body. The utility model discloses can reduce energy leakage in the bulk acoustic wave syntonizer, improve the Q value of bulk acoustic wave syntonizer, and when the acoustic reflection structure is the cavity structure, need not to make sacrificial layer release passageway to can simplify the preparation flow.

Description

Bulk acoustic wave resonator and bulk acoustic wave filter

Technical Field

The utility model relates to the field of semiconductor technology, especially, relate to a bulk acoustic wave syntonizer and bulk acoustic wave filter.

Background

The resonator is an electronic component generating a resonant frequency, has the characteristics of stability and good anti-interference performance, and is widely applied to various electronic products, such as filters.

The conventional resonator such as a bulk acoustic wave resonator generally comprises a substrate, and a bottom electrode, an acoustic reflection structure, a piezoelectric layer and a top electrode which are positioned on the surface of the substrate, wherein the contact area between the edge of the bottom electrode and the substrate in the conventional bulk acoustic wave resonator is large, so that the energy of the bulk acoustic wave resonator is excessively leaked through the substrate, and the Q value of the bulk acoustic wave resonator is reduced. In addition, when the acoustic reflection structure of the existing bulk acoustic wave resonator is a cavity structure, the sacrificial layer needs to be released before the cavity structure is formed, the sacrificial layer needs to be etched in the bulk acoustic wave resonator to release a channel, and the extra etching process makes the bulk acoustic wave resonator more cumbersome to manufacture.

SUMMERY OF THE UTILITY MODEL

The utility model provides a bulk acoustic wave syntonizer and bulk acoustic wave filter can reduce energy leakage in the bulk acoustic wave syntonizer, improves the Q value of bulk acoustic wave syntonizer, and when the sound reflection structure is the cavity structure, need not the preparation sacrificial layer release path to can simplify the preparation flow.

According to an aspect of the utility model provides a bulk acoustic wave syntonizer, bulk acoustic wave syntonizer includes: a substrate having a first surface and a second surface opposite the first surface; an acoustic reflection structure is arranged in the substrate and comprises a cavity structure or a groove, the cavity structure is positioned on the first surface side, and the groove penetrates through the first surface and the second surface; the substrate comprises a substrate body and a plurality of device supporting points which are connected with the substrate body and are arranged at intervals, and the device supporting points are arranged in the sound reflection structure;

the resonator, the resonator includes the stromatolite of bottom electrode, first piezoelectric layer and top electrode in proper order, the bottom electrode is close to the substrate sets up, the resonator is in at least partly of the perpendicular projection's on the substrate body border is located in the sound reflection structure, the device strong point is used for supporting the resonator.

Optionally, the device support point is for supporting at least one of a portion of the bottom electrode and a portion of the first piezoelectric layer.

Optionally, the same device support point is used to support a portion of the bottom electrode and a portion of the first piezoelectric layer.

Optionally, the device support point is used for supporting the first piezoelectric layer; a portion of the first piezoelectric layer is located on a first surface side of the device support point; the bottom electrode is in no contact with the device support point, and the top electrode is in no contact with the device support point;

or the device supporting point is used for supporting the bottom electrode; a portion of the bottom electrode is located on a first surface side of the device support site; the first piezoelectric layer is free of contact with the device support point and the top electrode is free of contact with the device support point.

Optionally, the device support points include a first device support point and a second device support point;

a portion of the first piezoelectric layer is located on a first surface side of the first device support point, the first device support point being for supporting a portion of the first piezoelectric layer, the top electrode being free of contact with the first device support point, the bottom electrode being free of contact with the first device support point; a portion of the bottom electrode is located on a first surface side of the second device support point, the second device support point is to support a portion of the bottom electrode, the first piezoelectric layer is free from contact with the second device support point, and the top electrode is free from contact with the second device support point.

Optionally, the device support point comprises a sixth device support point;

a portion of the bottom electrode and a portion of the first piezoelectric layer are located on a first surface side of the sixth device support point, the sixth device support point being for supporting the portion of the bottom electrode and the portion of the first piezoelectric layer, the top electrode being free of contact with the sixth device support point.

Optionally, the bulk acoustic wave resonator provided in this embodiment further includes a mass loading layer;

the mass loading layer is located on a side of the top electrode away from the first piezoelectric layer.

Optionally, the bulk acoustic wave resonator provided in this embodiment further includes a passivation layer;

the passivation layer is located on one side of the mass loading layer away from the top electrode.

Optionally, the shape of the vertical projection of the resonator body on the substrate body includes at least one of a circle, an ellipse, a crescent and a polygon.

Optionally, the shape of the vertical projection of the resonator body on the substrate body includes a polygon, and the device support point is used for supporting the vertex of the resonator body.

Optionally, the bulk acoustic wave resonator provided in this embodiment further includes a bottom electrode connection electrode, and the bottom electrode connection electrode is connected to the bottom electrode and extends to the surface of the substrate body.

According to the utility model discloses an on the other hand provides a bulk acoustic wave filter, and bulk acoustic wave filter includes the utility model discloses arbitrary embodiment provides a bulk acoustic wave syntonizer.

The embodiment provides a bulk acoustic wave resonator, which comprises a substrate and a resonator body, wherein the substrate comprises a substrate body and a plurality of spaced device supporting points connected with the substrate body. The resonator body includes bottom electrode, first piezoelectric layer and the top electrode of range upon range of setting in proper order, and the bottom electrode is close to the substrate setting. At least a part of the boundary of the perpendicular projection of the resonator body on the substrate body is located within the acoustically reflective structure, i.e. at least a part of the side face of the resonator body has a gap with the side face of the substrate body, and the resonator body may not be supported by the substrate body but may be supported by the device support points. When the acoustic reflection structure is a cavity structure, the sacrificial layer can be released through a gap between the resonator body and the substrate body before the cavity structure is formed, so that an additional sacrificial layer release channel is not required to be formed to release the sacrificial layer. Compared with the existing bulk acoustic wave resonator, the contact area between the resonator body and the substrate is greatly reduced, so that the energy leakage in the resonator body is reduced, the Q value of the bulk acoustic wave resonator is improved, and when the acoustic reflection structure is a cavity structure, a sacrificial layer release channel does not need to be manufactured, so that the manufacturing process can be simplified.

It should be understood that the statements herein are not intended to identify key or critical features of any embodiment of the present invention, nor are they intended to limit the scope of the invention. Other features of the present invention will become apparent from the following description.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic top view of a bulk acoustic wave resonator according to an embodiment of the present invention;

fig. 2 is a schematic top view of another bulk acoustic wave resonator according to an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view taken along line A1A2 of FIG. 1;

FIG. 4 is a schematic view of a further cross-sectional configuration taken along the line A1A2 of FIG. 1;

FIG. 5 is a schematic cross-sectional view taken along line B1B2 of FIG. 1;

FIG. 6 is a schematic view of a further cross-sectional configuration taken along the anatomical line B1B2 of FIG. 1;

FIG. 7 is a schematic representation of a further cross-sectional configuration taken along line B1B2 of FIG. 1;

FIG. 8 is a schematic representation of a further cross-sectional configuration taken along line B1B2 of FIG. 1;

FIG. 9 is a schematic representation of a further cross-sectional configuration taken along line B1B2 of FIG. 1;

FIG. 10 is a schematic view of a further cross-sectional structure taken along line B1B2 of FIG. 1;

FIG. 11 is a schematic view of a further cross-sectional configuration taken along the anatomical line B1B2 in FIG. 1;

FIG. 12 is a schematic view of a further cross-sectional configuration taken along the line A1A2 of FIG. 1;

fig. 13 is a schematic top view of a bulk acoustic wave filter according to an embodiment of the present invention;

FIG. 14 is a schematic representation of a structure dissected along section line A3A4 of FIG. 13;

fig. 15 to fig. 26 are schematic diagrams of a flow structure for forming the bulk acoustic wave resonator provided in this embodiment.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of 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 only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Fig. 1 is a schematic top view structure diagram of a bulk acoustic wave resonator according to an embodiment of the present invention, fig. 2 is a schematic top view structure diagram of another bulk acoustic wave resonator according to an embodiment of the present invention, fig. 3 is a schematic cross-sectional structure diagram obtained by dissection along an dissection line A1A2 in fig. 1, fig. 4 is a schematic cross-sectional structure diagram obtained by dissection along an dissection line A1A2 in fig. 1, fig. 5 is a schematic cross-sectional structure diagram obtained by dissection along an dissection line B1B2 in fig. 1, fig. 6 is a schematic cross-sectional structure diagram obtained by dissection along an dissection line B1B2 in fig. 1, and fig. 7 is a schematic cross-sectional structure diagram obtained by dissection along a dissection line B1B2 in fig. 1. Referring to fig. 1 to 7, the present embodiment provides a bulk acoustic wave resonator including: a substrate 110 and a resonator body 120, the substrate 110 including a first surface and a second surface opposite to the first surface; an acoustic reflection structure 111 is provided in the substrate 110, the acoustic reflection structure 111 including a cavity structure (refer to fig. 3) or a groove (refer to fig. 4), the cavity structure being located on the first surface side, the groove penetrating the first surface and the second surface; the substrate 110 includes a substrate body 112 and a plurality of spaced apart device support points 113 connected to the substrate body 112, the device support points 113 being disposed within the acoustic reflection structure 111; the resonator body 120 comprises a bottom electrode 121, a first piezoelectric layer 122 and a top electrode 123 arranged in a stack, the bottom electrode 121 being arranged close to the substrate 110, and with reference to fig. 1-4, at least a part of the border of the perpendicular projection of the resonator body 120 on the substrate body 112 is located within the acoustically reflective structure 111; referring to fig. 5-7, the device support points 113 are used to support the resonator body 120.

The resonator body 120 is located at a first surface side of the device support point 113, the first piezoelectric layer 122 in the resonator body 120 shown in fig. 1 completely covering the device support point 113, and the first piezoelectric layer 122 in the resonator body 120 shown in fig. 2 covering a part of the device support point 113. The material of the substrate 110 may be at least one of single crystal silicon, gallium arsenide, sapphire, quartz, and the like. The first piezoelectric layer 122 and the second piezoelectric layer 124 can be formed simultaneously and can each be aluminum nitride, with the second piezoelectric layer 124 being located on the first surface of the substrate body 112. The material of the bottom electrode 121 may be at least one of molybdenum, aluminum, and tungsten. The device supporting point 113 may be located inside the substrate body 112 (refer to fig. 5-7), a first surface of the device supporting point 113 may be flush with the first surface of the substrate body 112 (refer to fig. 5 and 7), or the first surface of the device supporting point 113 may have a certain distance from the first surface of the substrate body 112 (refer to fig. 6); the material of the device supporting point 113 may be the same as that of the substrate body 112, and the device supporting point 113 may be integrally connected with the substrate body 112.

The thickness of the device supporting point 113 may be less than or equal to the depth of the acoustic reflection structure 111, and by setting the thickness of the device supporting point 113 to be less than the depth of the acoustic reflection structure 111 (refer to fig. 5 and 6), the volume of the acoustic reflection structure 111 may be increased; by setting the thickness of the device support point 113 equal to the depth of the acoustic reflection structure 111 (refer to fig. 7), the stability of the device support point 113 supporting the resonator body 120 can be improved.

Referring to fig. 1-4, at least a portion of the boundary of the perpendicular projection of the resonator body 120 on the substrate body 112 is located within the acoustic reflection structure 111, i.e. at least a portion of the side of the resonator body 120 has a certain gap 114 with the side of the substrate body 112. A portion of the resonator body 120 may be in contact with the substrate body 112 and the remaining portion may be out of contact with the substrate body 112, or the entire resonator body 120 is out of contact with the substrate body 112, only in contact with the device support point 113; since the plurality of device supporting points 113 are distributed at intervals, compared with the bulk acoustic wave resonator in which the resonator body contacts the substrate body in the prior art, the contact area between the resonator body 120 and the substrate 110 in the embodiment is greatly reduced, so that the leakage of energy in the resonator body 120 into the substrate 110 can be reduced, and the Q value of the bulk acoustic wave resonator is improved.

In addition, when the acoustic reflection structure 111 is a cavity structure, in the process of manufacturing the bulk acoustic wave resonator, the sacrificial layer filled in the cavity structure needs to be removed, before the sacrificial layer is removed, the bulk acoustic wave resonator in the prior art needs to etch the sacrificial layer release channel, and in this embodiment, because at least a part of the boundary of the vertical projection of the resonator body 120 on the substrate body 112 is located in the acoustic reflection structure 111, when the sacrificial layer is removed, the sacrificial layer can be released through the gap 114 between the side surface of the resonator body 120 and the side surface of the substrate body 112, so that the sacrificial layer release channel does not need to be formed, the process steps are simplified, and the manufacturing efficiency of the bulk acoustic wave resonator is improved.

Optionally, the shape of the perpendicular projection of the resonator body on the substrate body includes at least one of a circle, an ellipse, a crescent, and a polygon.

Specifically, the shape of the vertical projection of the resonator on the substrate body may be a regular pattern or an irregular pattern, and for example, the shape of the vertical projection of the resonator 120 on the substrate body in the bulk acoustic wave resonator shown in fig. 2 is a pentagon.

Optionally, the shape of the perpendicular projection of the resonator body on the substrate body comprises a polygon, the device support points being for supporting vertices of the resonator body.

Specifically, referring to fig. 2, the device supporting point 113 of fig. 2 supports the apex of the resonator body 120, so that the resonator body 120 can be stably disposed on the device supporting point 113. Furthermore, the device support points 113 may also support the middle point on each side of the resonator body 120.

Optionally, the edge of the acoustic reflective structure is parallel to the boundary of the resonator body.

Specifically, referring to fig. 1, the edge of the acoustic reflection structure 111 in the bulk acoustic wave resonator shown in fig. 1 is parallel to the boundary of the resonator body 120.

Alternatively, the device supporting point 113 is for supporting at least one of a portion of the bottom electrode 121 and a portion of the first piezoelectric layer 122, and the device supporting point 113 may allow the resonator body 120 to be stably disposed on the first surface side of the device supporting point 113. In the bulk acoustic wave resonators shown in fig. 5-7 only a part of the first piezoelectric layer 122 is in contact with the device support point 113, i.e. the device support point 113 is used to support a part of the first piezoelectric layer 122. The bulk acoustic wave resonator provided in this embodiment may also be such that only a portion of the bottom electrode 121 contacts the device supporting point 113, may also be such that a portion of the bottom electrode 121 and a portion of the first piezoelectric layer 122 contact the same device supporting point 113, and may also be such that a portion of the bottom electrode 121 and a portion of the first piezoelectric layer 122 contact different device supporting points 113.

Specifically, providing the same device supporting point 113 for supporting the portion of the bottom electrode 121 and the portion of the first piezoelectric layer 122 can improve the stability of the resonator body 120 provided on the first surface side of the device supporting point 113. Exemplarily, referring to fig. 8, the bulk acoustic wave resonator shown in fig. 8 indicates that a portion of the bottom electrode 121 and a portion of the first piezoelectric layer 122 are both in contact with the same device supporting point 113.

The following is directed to a scheme in which the device support point supports one of a portion of the bottom electrode and a portion of the first piezoelectric layer.

Optionally, with continued reference to fig. 5-7, the device support points 113 are used to support the first piezoelectric layer 122; a portion of the first piezoelectric layer 122 is located on a first surface side of the device support point 113; the bottom electrode 121 is not in contact with the device support point 113, the top electrode 123 is not in contact with the device support point 113, the device support point 113 is only in contact with a portion of the first piezoelectric layer 122, and a vertical projection of the first piezoelectric layer 122 on the substrate body 112 may completely cover or partially cover a vertical projection of the device support point 113 on the substrate body 112.

Alternatively, referring to fig. 9, fig. 9 is a schematic cross-sectional view taken along the dissection line B1B2 in fig. 1, wherein the device supporting point 113 is used for supporting the bottom electrode 121; portions of the bottom electrode 121 are located on the first surface side of the device support point 113; the first piezoelectric layer 122 is free from contact with the device support point 113 and the top electrode 123 is free from contact with the device support point 113. Specifically, the device support point 113 is in contact with only the bottom electrode 121, which is not in contact with both the first piezoelectric layer 122 and the top electrode 123. The vertical projection of the bottom electrode 121 on the substrate body 112 may completely cover or cover part of the vertical projection of the device support point 113 on the substrate body 112.

The following is a description of a solution in which two differently located device support points support a portion of the bottom electrode and a portion of the first piezoelectric layer, respectively.

Alternatively, referring to FIG. 10, FIG. 10 is a schematic view of a further cross-sectional configuration taken along anatomical line B1B2 of FIG. 1, device support points 113 including a first device support point 10 and a second device support point 20; a portion of the first piezoelectric layer 122 is located on a first surface side of the first device support point 10, the first device support point 10 is for supporting the portion of the first piezoelectric layer 122, the top electrode 123 is free from contact with the first device support point 10, and the bottom electrode 121 is free from contact with the first device support point 10; a portion of the bottom electrode 121 is located on a first surface side of the second device support point 20, the second device support point 20 is for supporting a portion of the bottom electrode 121, the first piezoelectric layer 122 is free from contact with the second device support point 20, and the top electrode 123 is free from contact with the second device support point 20.

Specifically, the plurality of device support points 113 may be divided into two parts, one part being the first device support points 10 and the other part being the second device support points 20, the first device support points 10 may be in contact with only the first piezoelectric layer 122, and the second device support points 20 may be in contact with only the bottom electrode 121.

It should be noted that the relative position between the first device supporting point 10 and the second device supporting point 20 in the embodiment of the present invention is not limited.

The following is a description of a scheme in which one device supporting point supports a portion of the bottom electrode and a portion of the first piezoelectric layer.

Alternatively, referring to FIG. 11, FIG. 11 is a schematic view of a further cross-sectional configuration dissected along dissection line B1B2 of FIG. 1, with device support points 113 including a sixth device support point 30; the part of the bottom electrode 121 and the part of the first piezoelectric layer 122 are located on the first surface side of the sixth device support point 30, the sixth device support point 30 is for supporting the part of the bottom electrode 121 and the part of the first piezoelectric layer 122, and the top electrode 123 is free from contact with the sixth device support point 30.

Specifically, the sixth device support point 30 may be in contact with portions of the bottom electrode 121 and portions of the first piezoelectric layer 122, and the sixth device support point 30 is not in contact with the top electrode 123.

Alternatively, referring to fig. 12, fig. 12 is a schematic cross-sectional structure view obtained by dissection along a dissection line A1A2 in fig. 1, and the bulk acoustic wave resonator provided in this embodiment further includes a mass loading layer 130, where the mass loading layer 130 is located on a side of the top electrode 123 away from the first piezoelectric layer 122.

In particular, the mass loading layer 130 is used to adjust the operating frequency of the bulk acoustic wave resonator. The material of the mass loading layer 130 may be the same as the material of the bottom electrode 121 or the top electrode 123.

Optionally, with continuing reference to fig. 12, the bulk acoustic wave resonator provided in this embodiment further includes a passivation layer 140, where the passivation layer 140 is located on a side of the mass loading layer 130 away from the top electrode 123.

In particular, the passivation layer 140 is also used to adjust the operating frequency of the bulk acoustic wave resonator. The material of the passivation layer 140 may include aluminum nitride.

Optionally, the bulk acoustic wave resonator provided in this embodiment further includes a bottom electrode connection electrode, the bottom electrode connection electrode is connected to the bottom electrode 121 and extends to the surface of the substrate body 112, and the bottom electrode connection electrode is used for transmitting an electrical signal to the bottom electrode 121.

This embodiment still provides a bulk acoustic wave filter, and this bulk acoustic wave filter includes the utility model discloses arbitrary embodiment provides a bulk acoustic wave resonator.

Alternatively, referring to fig. 13, fig. 13 is a schematic diagram of a top-view structure of a bulk acoustic wave filter according to an embodiment of the present invention, where the bulk acoustic wave filter provided by this embodiment includes at least two bulk acoustic wave resonators, the at least two bulk acoustic wave resonators include a first bulk acoustic wave resonator 101 and a second bulk acoustic wave resonator 102, and the first bulk acoustic wave resonator 101 and the second bulk acoustic wave resonator 101 are connected in series or in parallel through a connection electrode 103.

Specifically, the bottom electrode 121 of the first bulk acoustic resonator 101 is connected to the bottom electrode 121 of the second bulk acoustic resonator 102 via the connection electrode 103, and the top electrode 123 of the first bulk acoustic resonator 101 is connected to the top electrode 123 of the second bulk acoustic resonator 102 via the connection electrode 103, so that the first bulk acoustic resonator 101 and the second bulk acoustic resonator 102 are connected in parallel. The bottom electrode 121 of the first bulk acoustic resonator 101 is connected to the top electrode 123 of the second bulk acoustic resonator 102 via the connecting electrode 103, and the first bulk acoustic resonator 101 and the second bulk acoustic resonator 102 can be connected in series. Referring to fig. 14, fig. 14 is a schematic structural diagram dissected along a section line A3A4 in fig. 13, the film layer structure in the first bulk acoustic wave resonator 101 may be different from that in the second bulk acoustic wave resonator 102, and for example, the first bulk acoustic wave resonator 101 may include the mass loading layer 130, and the second bulk acoustic wave resonator 102 may not include the mass loading layer.

The embodiment also provides a method for manufacturing the bulk acoustic wave resonator, which comprises the following steps:

s110, providing a substrate, forming a cavity structure, and forming a sacrificial layer in the cavity structure, wherein the substrate comprises a substrate body and a plurality of device supporting points connected with the substrate body.

Referring to fig. 15, fig. 15 is a schematic top view of the sacrificial layer 210 formed in the substrate 110, and fig. 16 is a schematic structure view dissected along the section line C1C2 in fig. 15. The cavity structure may be filled with the sacrificial layer 210 through a plating process. In the subsequent step, the sacrificial layer 210 is etched by an etching solution, so that a cavity structure serving as an acoustic reflection structure can be obtained. Illustratively, the sacrificial layer 210 comprises a material of an oxide of silicon, such as: phosphosilicate Glass (PSG).

And S120, forming a bottom electrode and a bottom electrode connecting electrode on one side of the sacrificial layer far away from the substrate body.

Referring to fig. 17 and 18, fig. 17 is a schematic top view of the bottom electrode 121 and the bottom electrode connecting electrode formed on the sacrificial layer 210 on the side away from the substrate body 112, and fig. 18 is a schematic structural view dissected along a section line D1D2 in fig. 17. A transition electrode layer may be formed on a side of the sacrificial layer 210 away from the substrate 110 by a plating process, where the transition electrode layer covers the sacrificial layer 210 and the first surface of the substrate 110; and then patterning the transition electrode layer by photolithography and etching processes to form a bottom electrode 121 and a bottom electrode connection electrode, wherein the material of the bottom electrode 121 and the bottom electrode connection electrode may be at least one of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, and titanium.

And S130, forming a piezoelectric transition layer on one side of the bottom electrode far away from the substrate body.

Referring to fig. 19 and 20, fig. 19 is a schematic top view of the piezoelectric transition layer 222 formed on the side of the bottom electrode 121 away from the substrate body 112, and fig. 20 is a schematic structural view dissected along a section line E1E2 in fig. 19. The first piezoelectric layer transition layer 222 may be formed on the side of the bottom electrode 121 away from the sacrificial layer 210 by a plating process.

And S140, forming a top electrode transition layer on one side of the piezoelectric transition layer far away from the substrate body.

Referring to fig. 21, fig. 21 is a schematic structural diagram of forming a top electrode transition layer 223 on a side of the piezoelectric transition layer 222 away from the substrate body 112. The top electrode transition layer 223 may be formed on a side of the piezoelectric transition layer 222 away from the substrate body 112 by a plating process.

And S150, forming a mass load transition layer on one side, far away from the piezoelectric transition layer, of the top electrode transition layer.

Referring to fig. 22, fig. 22 is a schematic structural diagram of the mass load transition layer 131 formed on the top electrode transition layer 223 on the side away from the piezoelectric transition layer 222.

And S160, forming a passivation transition layer on one side of the mass load transition layer far away from the top electrode transition layer.

Referring to fig. 23, fig. 23 is a schematic structural diagram of forming a passivation transition layer 141 on a side of the mass loading transition layer 131 away from the top electrode transition layer 223.

S170, etching the top electrode transition layer, the mass load transition layer and the passivation transition layer to form a top electrode, a mass load layer and a passivation layer.

Referring to fig. 23 and 24, fig. 24 is a schematic structural diagram of forming the top electrode 123, the mass loading layer 130 and the passivation layer 140, and before etching the top electrode transition layer 223, the mass loading transition layer 131 and the passivation transition layer 141, a photoresist is coated, and then exposed and developed; then, an etching process is performed to form the top electrode 123, the mass loading layer 130, and the passivation layer 140.

And S180, etching the part of the piezoelectric transition layer which is not positioned on the first surface side of the device supporting point to form a passivation layer.

Referring to fig. 24 and 25, fig. 25 is a schematic structural diagram of forming the first piezoelectric layer 122 and the second piezoelectric layer 124. Portions of the piezoelectric transition layer 222 are etched until portions of the sacrificial layer 210 are exposed and the gap 114 is formed. Before etching the part of the piezoelectric transition layer 222 which is not positioned on the first surface side of the device supporting point, coating photoresist, exposing and developing; then, an etching process is performed to form the first piezoelectric layer 122 and the second piezoelectric layer 124.

And S190, removing the sacrificial layer.

Referring to fig. 12 and 25, fig. 12 is a schematic structural view after the sacrificial layer is removed. The sacrificial layer 210 may be etched by an etchant, so that the sacrificial layer 210 is removed to form a cavity structure. The present embodiment uses the gap 114 formed in step S180 as a sacrificial layer release channel, and does not need to add a sacrificial layer release channel. In addition, the coverage of the gap is large, and the sacrificial layer 140 can be released cleanly.

And S200, forming a bonding layer on one side of the first piezoelectric layer far away from the substrate body, and bonding the bonding layer with a wafer.

Referring to fig. 26, fig. 26 is a schematic structural diagram of the first piezoelectric layer 122 after forming a bonding layer 160 on a side away from the substrate body 112 and bonding with a wafer 170. The material of bonding layer 160 may be gold.

It should be understood that various forms of the flows shown above may be used, with steps reordered, added, or deleted. For example, the steps described in the present invention may be executed in parallel, may be executed sequentially, or may be executed in different orders, as long as the desired result of the technical solution of the present invention can be achieved, and the present invention is not limited thereto.

The above detailed description does not limit the scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A bulk acoustic wave resonator, comprising:

a substrate having a first surface and a second surface opposite the first surface; an acoustic reflection structure is arranged in the substrate and comprises a cavity structure or a groove, the cavity structure is positioned on the first surface side, and the groove penetrates through the first surface and the second surface; the substrate comprises a substrate body and a plurality of device supporting points which are connected with the substrate body and arranged at intervals, and the device supporting points are arranged in the sound reflection structure;

2. The bulk acoustic wave resonator according to claim 1, wherein the device support point is configured to support at least one of a portion of the bottom electrode and a portion of the first piezoelectric layer.

3. The bulk acoustic wave resonator according to claim 2, characterized in that the same device support point is used for supporting part of the bottom electrode and part of the first piezoelectric layer.

4. The bulk acoustic wave resonator according to claim 1 or 2, characterized in that the device support point is for supporting the first piezoelectric layer; a portion of the first piezoelectric layer is located on a first surface side of the device support point; the bottom electrode is in no contact with the device support point, and the top electrode is in no contact with the device support point;

5. The bulk acoustic wave resonator according to claim 1 or 2, characterized in that the device support points comprise a first device support point and a second device support point;

6. The bulk acoustic wave resonator according to claim 3, wherein the device support point comprises a sixth device support point;

7. The bulk acoustic wave resonator according to claim 1, further comprising a mass loading layer;

8. The bulk acoustic wave resonator according to claim 7, further comprising a passivation layer;

9. The bulk acoustic wave resonator according to claim 1, wherein a shape of a perpendicular projection of the resonator body on the substrate body comprises at least one of a circle, an ellipse, a crescent, and a polygon.

10. The bulk acoustic wave resonator according to claim 9, characterized in that the shape of the perpendicular projection of the resonator body on the substrate body comprises a polygon, the device support points being used to support the vertices of the resonator body.

11. The bulk acoustic wave resonator according to claim 1, further comprising a bottom electrode connection electrode connected to the bottom electrode extending to a surface of the substrate body.

12. A bulk acoustic wave filter comprising the bulk acoustic wave resonator according to any one of claims 1 to 11.