Resonator manufacturing method and resonator

Abstract

The invention discloses a resonator manufacturing method and a resonator. The resonator manufacturing method comprises the steps that a first electrode layer, a piezoelectric layer and a second electrode layer are sequentially manufactured in a stacked mode; a first hole penetrating through the second electrode layer is manufactured, a plurality of second electrodes are obtained, and part of the surface of the piezoelectric layer is exposed out of the first hole; a through groove is formed in the exposed surface of the piezoelectric layer, a plurality of piezoelectric bodies are obtained, and the through groove is located between the two second electrodes; manufacturing a sacrificial layer comprising a plurality of convex parts, forming a groove by two adjacent convex parts, and exposing the through groove in the groove; manufacturing a cut-off boundary layer to cover one side of the lug boss, the wall surface of the groove, the wall surface of the through groove, a part of the second electrode, a part of the piezoelectric body and a part of the first electrode layer; a second hole penetrating through the first electrode layer is manufactured, a plurality of first electrodes are obtained, part of the surface of the piezoelectric layer is exposed out of the second hole, and part of the cut-off boundary layer is exposed out of the second hole; and removing the lug boss corresponding to the second electrode to form a cavity. According to the method, the stress mismatch between the cut-off boundary layer and the piezoelectric layer can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of resonators, and in particular to a method for manufacturing a resonator and a resonator. Background Art

[0002] Bulk acoustic wave filters are widely used in modern wireless communications and electronic devices due to their high performance and miniaturization, such as mobile communications, wireless network equipment, satellite communications, etc.

[0003] The resonator is an important component of the bulk acoustic wave filter. In the prior art, during the manufacturing process of the resonator, the piezoelectric layer will generate large stress due to its material, structure and deposition process. At the same time, at least a part of the piezoelectric layer is covered with a cutoff boundary layer on one side. Since the material and manufacturing process of the piezoelectric layer may be different from those of the cutoff boundary layer, it may cause stress mismatch between the piezoelectric layer and the cutoff boundary layer, which in turn affects the performance and reliability of the resonator. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to reduce the stress mismatch between the piezoelectric layer and the cut-off boundary layer during the manufacturing process of the resonator.

[0005] In order to solve at least one of the above-mentioned technical problems, the present invention discloses a method for manufacturing a resonator and a resonator.

[0006] According to one aspect of the present disclosure, a method for manufacturing a resonator and a resonator are provided, comprising: The first electrode layer, the piezoelectric layer and the second electrode layer are sequentially stacked; Making a first hole on the second electrode layer, wherein the first hole penetrates the second electrode layer so that a portion of the surface of the piezoelectric layer is exposed in the first hole, and the first hole divides the second electrode layer into a plurality of second electrodes; A through groove is made on the exposed surface of the piezoelectric layer, the through groove penetrates the piezoelectric layer and divides the piezoelectric layer into a plurality of piezoelectric bodies, and a portion of the surface of the first electrode layer is exposed in the through groove, and the through groove is located between two adjacent second electrodes; Making a second hole on the first electrode layer, the second hole penetrates the first electrode layer, so that a portion of the surface of the piezoelectric layer is exposed in the second hole, and the second hole divides the first electrode layer into a plurality of first electrodes, and a side of the cutoff boundary layer in the through groove facing away from the bonding contact layer is exposed in the second hole; For each of the second electrodes, at least one protrusion connected to the second electrode is removed, so that at least one cavity is formed between a side of each of the second electrodes facing away from the piezoelectric layer and the cutoff boundary layer.

[0007] In some possible embodiments, after forming the through groove on the exposed surface of the piezoelectric layer, the method further includes: A sacrificial layer is made on the side of the second electrode layer away from the piezoelectric layer, the sacrificial layer includes a plurality of spaced-apart protrusions, and a groove is formed between two adjacent protrusions, the through groove is exposed in one of the grooves, wherein each of the second electrodes is connected to at least two protrusions.

[0008] In some possible embodiments, after the sacrificial layer is formed, the method further includes: A cut-off boundary layer is manufactured, wherein the cut-off boundary layer covers the side of the protrusion away from the piezoelectric layer, the wall surface of the groove, the wall surface of the through groove, and covers the second electrode and the piezoelectric body exposed at the groove and the first electrode layer exposed at the through groove; A bonding contact layer is manufactured, which fills each groove and the through groove respectively and covers a side of the cut-off boundary layer away from the sacrificial layer; a side of the cut-off boundary layer in the through groove away from the bonding contact layer is exposed from the second hole.

[0009] In some possible embodiments, a surface of a side of the cut-off boundary layer located in the through groove facing away from the bonding contact layer is flush with a surface of a side of the piezoelectric layer facing away from the second electrode layer.

[0010] In some possible embodiments, before forming a plurality of second holes on the first electrode layer, the method includes: A packaging substrate is provided, and the packaging substrate is bonded to the bonding contact layer.

[0011] In some possible embodiments, the multiple first electrodes correspond one-to-one to the multiple piezoelectric bodies, and the multiple piezoelectric bodies correspond one-to-one to the multiple second electrodes. In the stacking direction of the resonator, the corresponding projections of the first electrodes, the projections of the piezoelectric bodies, and the projections of the second electrodes at least partially overlap.

[0012] In some possible embodiments, the method further includes: Making a plurality of third holes on each of the piezoelectric bodies, wherein the plurality of third holes penetrate the piezoelectric body so that a portion of the surface of the second electrode corresponding to the piezoelectric body is exposed from the third holes; Manufacturing a plurality of first conductive structures, wherein the first conductive structures correspond to the first electrodes one by one, and the first conductive structures cover a portion of the surface of the corresponding first electrode facing away from the piezoelectric body; A plurality of second conductive structures are manufactured, wherein the second conductive structures correspond to the third holes one by one, and the second conductive structures cover the inner sidewalls of the corresponding third holes and extend to cover the second electrodes exposed in the third holes.

[0013] In some possible embodiments, removing at least one protrusion connected to the second electrode from each of the second electrodes so that at least one cavity is formed between a side of each of the second electrodes facing away from the piezoelectric layer and the cut-off boundary layer, includes: The piezoelectric body is provided with a release hole that penetrates the piezoelectric body. The etching liquid is injected through the release hole to corrode at least one protrusion connected to the second electrode for each second electrode, so as to form the at least one cavity between the side of each second electrode away from the piezoelectric layer and the cut-off boundary layer.

[0014] According to a second aspect of the present disclosure, a resonator is provided, the resonator comprising: A first electrode layer, a piezoelectric layer and a second electrode layer are stacked; The first electrode layer is provided with second holes to form a plurality of first electrodes arranged at intervals; the second electrode layer is provided with first holes to form a plurality of second electrodes arranged at intervals; A through groove is formed on the side of the piezoelectric layer away from the second electrode layer to form a plurality of piezoelectric bodies arranged at intervals, and the through groove is located between two adjacent first electrodes and also between two adjacent second electrodes; For each of the second electrodes, at least one protrusion connected to the second electrode is removed, so that at least one cavity is formed between a side of each of the second electrodes facing away from the piezoelectric layer and the cutoff boundary layer.

[0015] In some possible embodiments, a sacrificial layer is further provided on the surface of the second electrode layer facing away from the piezoelectric layer, the sacrificial layer includes a plurality of spaced-apart protrusions, and a groove is formed between two adjacent protrusions, the through groove is connected to one of the grooves, wherein each of the second electrodes is connected to at least two protrusions.

[0016] In some possible embodiments, a cutoff boundary layer is provided on a side of the sacrificial layer away from the piezoelectric layer, and the cutoff boundary layer covers a side of the protrusion away from the piezoelectric layer, a wall surface of the groove, a wall surface of the through groove, and covers the second electrode and the piezoelectric body exposed at the groove; A bonding contact layer is provided on the side of the cut-off boundary layer away from the sacrificial layer, and the bonding contact layer fills each of the grooves and covers the surface of the side of the cut-off boundary layer away from the sacrificial layer; the side of the cut-off boundary layer in the through groove away from the bonding contact layer is exposed from the second hole.

[0017] In some possible embodiments, a surface of a side of the cut-off boundary layer located in the through groove facing away from the bonding contact layer is flush with a surface of a side of the piezoelectric layer facing away from the second electrode layer.

[0018] In some possible embodiments, the multiple first electrodes correspond one-to-one to the multiple piezoelectric bodies, and the multiple piezoelectric bodies correspond one-to-one to the multiple second electrodes. In the stacking direction of the resonator, the corresponding projections of the first electrodes, the projections of the piezoelectric bodies, and the projections of the second electrodes at least partially overlap.

[0019] In some possible embodiments, the resonator further includes: a plurality of first conductive structures, wherein the first conductive structures correspond to the first electrodes one by one, and the first conductive structures cover a portion of a surface of the corresponding first electrode that is away from the piezoelectric body; A plurality of second conductive structures, wherein the first conductive structure and the second electrode correspond one to one, a third hole penetrating the piezoelectric body is provided on a side of each piezoelectric body away from the second electrode, the second electrode corresponding to the piezoelectric body is exposed in the third hole, and the second conductive structure covers the inner side wall of the corresponding third hole and covers the second electrode exposed in the third hole.

[0020] The implementation of the present invention has the following beneficial effects: In the resonator manufacturing method disclosed in the present invention, after a first hole is etched through the second electrode layer so that a portion of the surface of the piezoelectric layer is exposed through the first hole, a through groove is etched through the piezoelectric layer on the exposed portion of the surface of the piezoelectric layer, and the through groove can divide the piezoelectric layer into a plurality of piezoelectric bodies so that the stress of the piezoelectric layer can be redistributed, thereby reducing local stress, reducing stress concentration and achieving uniform distribution of stress on a plurality of piezoelectric bodies; in addition, after the through groove is etched on the piezoelectric layer and a sacrificial layer is made, the through groove is exposed in a groove formed by two protruding portions, and a cut-off boundary layer is made at this time, which can cover the wall of the through groove covered by the cut-off boundary layer and the piezoelectric layer exposed at the through groove, so that the piezoelectric layer can adapt to the deformation of the cut-off boundary layer, thereby better adapting to thermal expansion and contraction, and reducing the stress mismatch between the two; at the same time, the through groove can provide space to alleviate the thermal stress caused by the difference in thermal expansion coefficient caused by the difference between the material of the piezoelectric layer and the material of the cut-off boundary layer, thereby reducing the stress mismatch between the two. Furthermore, since through-groove etching is performed after etching the first hole, the piezoelectric layer is divided into multiple piezoelectric bodies to reduce the stress of the piezoelectric layer. This can reduce wafer bending due to excessive stress or uneven stress, thereby avoiding the impact of wafer bending on the manufacturing accuracy and quality of the resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic flow chart corresponding to a method for manufacturing a resonator provided in an embodiment of the present invention; Figure 2 is a schematic structural diagram of constructing a sandwich structure on a supporting substrate provided by an embodiment of the present invention; Figure 3 is a schematic diagram of a structure for manufacturing a second electrode provided by an embodiment of the present invention; Figure 4 is a schematic diagram of the structure of manufacturing a piezoelectric body provided by an embodiment of the present invention; Figure 5 is a schematic diagram of a structure for manufacturing a sacrificial layer on a second electrode layer provided by an embodiment of the present invention; Figure 6 is a schematic diagram of a structure for making a cut-off boundary layer provided by an embodiment of the present invention; Figure 7 is a schematic diagram of a structure for manufacturing a bonding contact layer provided by an embodiment of the present invention; Figure 8is a schematic structural diagram of bonding between a packaging substrate and a bonding contact layer provided by an embodiment of the present invention; Fig. 9 is a schematic diagram of a structure in which a supporting substrate is removed according to an embodiment of the present invention; Fig.10 is a schematic diagram of a structure for manufacturing a first electrode provided by an embodiment of the present invention; Fig.11 is a schematic diagram of the structure of etching a third hole provided by an embodiment of the present invention; Fig.12 is a schematic structural diagram of forming a conductive structure provided by an embodiment of the present invention; Fig.13 It is a schematic structural diagram of a cavity formed after a portion of the sacrificial layer is corroded according to an embodiment of the present invention.

[0023] The reference numerals are as follows: 100-support substrate; 200-first electrode layer, 210-first electrode, 220-second hole; 300 - piezoelectric layer, 310 - piezoelectric body, 320 - through groove, 330 - third hole, 340 - release hole; 400 - second electrode layer, 410 - second electrode, 420 - first hole; 500-sacrificial layer, 510-protrusion, 520-groove, 530-cavity; 600 - cut-off boundary layer; 700-bonding contact layer; 800- packaging substrate; 900 - first conductive structure, 910 - second conductive structure. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the described embodiments are part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0026] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0027] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0028] The term "and / or" herein is a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may indicate the existence of A alone, A and B at the same time, and B alone. In addition, the term "at least one" herein indicates any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C may indicate including any one or more elements selected from the set consisting of A, B, and C.

[0029] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present disclosure.

[0030] Figure 1 A schematic diagram of the process flow corresponding to the resonator manufacturing method provided in the embodiment of the present invention; please refer to Figure 1 , a method for manufacturing a resonator, comprising: S1: stacking a first electrode layer 200, a piezoelectric layer 300 and a second electrode layer 400 in sequence; In a specific embodiment, Figure 2is a schematic diagram of a sandwich structure constructed on a supporting substrate according to an embodiment of the present invention. Figure 2 , a supporting substrate 100 is usually used to assist in the production of the first electrode layer 200, the piezoelectric layer 300 and the second electrode layer 400 in the resonator; wherein the supporting substrate 100 can be a carrier wafer, and a wafer with supporting capacity and matching the production requirements such as mechanical strength and thermal expansion coefficient can be selected as the carrier wafer, such as a silicon wafer, a glass wafer, etc.; since the first electrode layer 200, the piezoelectric layer 300 and the second electrode layer 400 are all thin film structures, they are thin in thickness and have low mechanical strength, and are prone to bending, warping and cracking. Therefore, providing a supporting substrate 100 to assist can improve the stability and safety of the resonator manufacturing process, and protect the first electrode layer 200, the piezoelectric layer 300 and the second electrode layer 400.

[0031] The above-mentioned first electrode layer 200, piezoelectric layer 300 and second electrode layer 400 can all be made by deposition. The material of the first electrode layer 200 and the second electrode layer 400 can be one of molybdenum or tungsten or a mixture of the two. The material of the piezoelectric layer 300 can be selected from one of polycrystalline or single crystal or polycrystalline single crystal mixed aluminum nitride, aluminum nitride scandium, quartz and other materials or a combination of at least two. These materials will produce charge separation or mechanical deformation when pressure or electric field is applied, thereby realizing the piezoelectric effect. Different piezoelectric materials have different properties and characteristics. In actual applications, suitable materials can be selected according to specific application requirements to deposit the first electrode layer 200, piezoelectric layer 300 and second electrode layer 400. After deposition, the sandwich structure is as follows Figure 2 shown.

[0032] S2: making a first hole 420 on the second electrode layer 400 , wherein the first hole 420 penetrates the second electrode layer 400 , so that a portion of the surface of the piezoelectric layer 300 is exposed in the first hole 420 , and the first hole 420 divides the second electrode layer 400 into a plurality of second electrodes 410 ; In a specific embodiment, Figure 3 is a schematic diagram of the structure of manufacturing the second electrode provided by an embodiment of the present invention; Figure 3 As shown, a plurality of second electrodes 410 can be obtained after the second electrode layer 400 is divided by the first hole 420. The lengths of the plurality of second electrodes 410 can be the same or different according to actual needs. The first hole 420 can be obtained by etching the second electrode layer 400. The first hole 420 penetrates the second electrode layer 400 so that a portion of the surface of the piezoelectric layer 300 is exposed in the first hole 420. After etching the first hole 420, the second electrode layer 400 is divided into a plurality of second electrodes 410 by the first hole 420. Figure 3 , the number of the second electrodes 410 may be two.

[0033] It should be noted that the present invention takes the manufacturing process of two resonators as an example for explanation, so the number of the first hole 420 can be 1, and the number of the second electrode 410 can be two; in actual application, the number of the first hole 420 can be set based on actual needs, and the number of the corresponding second electrodes 410 can change accordingly. In addition, the number of the second hole 220, the third hole 330, the release hole 340, the protrusion 510, the through groove 320 and the cavity 530 mentioned later can also be set according to actual needs, and the number of the first electrode 210, the piezoelectric body 310 and the groove 520 will also change accordingly.

[0034] S3: making a through groove 320 on the exposed surface of the piezoelectric layer 300, wherein the through groove 320 penetrates the piezoelectric layer 300 and divides the piezoelectric layer 300 into a plurality of piezoelectric bodies 310, and a portion of the surface of the first electrode layer 200 is exposed in the through groove 320, and the through groove 320 is located between two adjacent second electrodes 410; In a specific embodiment, since the piezoelectric layer 300 itself has stress in its structure and the differences in materials and thermal expansion coefficients between the various layers of the structure will also produce greater stress, after etching the first hole 420 on the second electrode layer 400, the piezoelectric layer 300 is exposed at the position of the first hole 420, and a through groove 320 that penetrates the piezoelectric layer 300 is made on the exposed surface of the piezoelectric layer 300 to reduce the stress in the piezoelectric layer 300 itself.

[0035] Figure 4 Schematic diagram of the structure of manufacturing a piezoelectric body provided by an embodiment of the present invention; Figure 4 As shown, the provision of the through groove 320 can divide the piezoelectric layer 300 into a plurality of piezoelectric bodies 310. The number of the plurality of piezoelectric bodies 310 can be two, and the lengths of the plurality of piezoelectric bodies 310 can be the same or different. The position of the through groove 320 can be adaptively adjusted according to the length and number of the piezoelectric bodies 310. For example, when the number of the piezoelectric bodies 310 is two and the lengths of the two piezoelectric bodies 310 are equal, the position of the through groove 320 should be at the midpoint of two adjacent piezoelectric bodies 310.

[0036] The provision of the through groove 320 can provide space to relieve the thermal stress caused by the difference in thermal expansion coefficient between the material of the piezoelectric layer 300 and the material of other layers, thereby reducing the stress mismatch between the piezoelectric layer 300 and other layers. Furthermore, since the through groove 320 is etched after the first hole 420 is etched, the piezoelectric layer 300 is divided into a plurality of piezoelectric bodies 310 and the stress of the piezoelectric layer 300 is reduced, it is possible to reduce the occurrence of wafer bending due to excessive stress or uneven stress, thereby avoiding the influence of wafer bending on the manufacturing accuracy and quality of the resonator.

[0037] S4: forming a sacrificial layer 500 on a side of the second electrode layer 400 away from the piezoelectric layer 300, wherein the sacrificial layer 500 includes a plurality of protrusions 510 arranged at intervals, and a groove 520 is formed between two adjacent protrusions 510, and the through groove 320 is exposed in one of the grooves 520, wherein each second electrode 410 is connected to at least two protrusions 510; In a specific embodiment, the sacrificial layer 500 can provide mechanical support to ensure the flatness and integrity of other layers. At the same time, the cavity 530 can be constructed by etching the sacrificial layer 500 so that the cavity 530 is used to achieve the propagation or resonance of sound waves.

[0038] Specifically, Figure 5 is a schematic diagram of a structure in which a sacrificial layer is fabricated on a second electrode layer according to an embodiment of the present invention. Figure 5 As shown, the sacrificial layer 500 can be obtained by depositing and etching on the side of the second electrode layer 400 away from the piezoelectric layer 300. The material of the sacrificial layer 500 can be silicon, silicon dioxide, silicon nitride compounds, and other materials that can be corroded by acid. First, a sacrificial layer 500 of a preset thickness is deposited. The sacrificial layer 500 of the preset thickness covers each second electrode 410 and covers the piezoelectric body 310 exposed between two adjacent second electrodes 410. Then, the sacrificial layer 500 of the preset thickness is etched so that a plurality of spaced-apart protrusions 510 are formed on the sacrificial layer 500, and a groove 520 is formed between two adjacent protrusions 510. Among the plurality of protrusions 510, there is a protrusion 510 covering at least a portion of the second electrode 410, and at least two protrusions 510 can be connected to each second electrode 410; the through groove 320 is exposed from one of the grooves 520, and at least a portion of each second electrode 410 is exposed from one of the grooves 520. Specifically, in the embodiments provided in the present application, with reference to Figure 5 Each piezoelectric body 310 is connected to at least one protrusion 510, and the protrusion 510 is used to support the piezoelectric body 310 on the side of the piezoelectric body 310 away from the first electrode layer 200. Each second electrode 410 is connected to at least one protrusion 510, and the protrusion 510 is used to support the second electrode 410 on the side of the second electrode 410 away from the piezoelectric body 310.

[0039] S5: manufacturing a cut-off boundary layer 600, wherein the cut-off boundary layer 600 covers the side of the protrusion 510 away from the piezoelectric layer 300, the wall surface of the groove 520, the wall surface of the through groove 320, and covers the second electrode 410 and the piezoelectric body 310 exposed at the groove 520 and the first electrode layer 200 exposed at the through groove 320; In a specific embodiment, Figure 6is a schematic diagram of a structure for making a cut-off boundary layer provided by an embodiment of the present invention, such as Figure 6 As shown, the cut-off boundary layer 600 is located on the side of the sacrificial layer 500 away from the second electrode layer 400. Specifically, the cut-off boundary layer 600 can be deposited on the side of the sacrificial layer 500 away from the second electrode layer 400, so that the cut-off boundary layer 600 covers the side of the protrusion 510 away from the piezoelectric layer 300, the wall surface of the groove 520, the wall surface of the through groove 320, and covers the second electrode 410 and the piezoelectric body 310 exposed at the groove 520, and covers the first electrode layer 200 exposed at the through groove 320. The material of the cut-off boundary layer 600 can be any material that can resist acid corrosion, such as polycrystalline silicon, single crystal silicon, amorphous silicon, etc., and the material of the cut-off boundary layer 600 can also be selected according to specific needs.

[0040] S6: manufacturing a bonding contact layer 700 , wherein the bonding contact layer 700 fills each groove 520 and the through groove 320 respectively, and covers a side of the cut-off boundary layer 600 away from the sacrificial layer 500 ; In a specific embodiment, Figure 7 is a schematic diagram of the structure of making a bonding contact layer provided by an embodiment of the present invention, such as Figure 7 As shown, the bonding contact layer 700 can be made by deposition, so that the bonding contact layer 700 can fill each groove 520 and the through groove 320 respectively, and cover the side of the cut-off boundary layer 600 away from the sacrificial layer 500. Further, the side of the bonding contact layer 700 away from the cut-off boundary layer 600 is polished, preferably by chemical mechanical polishing CMP, so that the side of the bonding contact layer away from the cut-off boundary layer 600 is flat and uniform. The material of the bonding contact layer 700 can be selected from one or a mixture of at least two materials such as undoped silicate glass material, phosphorus silicon glass, silicon nitride, etc., and the material selection can also be realized according to specific needs.

[0041] S7: A second hole 220 is made on the first electrode layer 200, and the second hole 220 penetrates the first electrode layer 200, so that part of the surface of the piezoelectric layer 300 is exposed in the second hole 220, and the second hole 220 divides the first electrode layer 200 into a plurality of first electrodes 210, and the cutoff boundary layer 600 located in the through groove 320 is exposed from the second hole 220 on the side away from the bonding contact layer 700. In other words, in the stacking direction of the resonator, the projection of the through groove pre-opened on the piezoelectric layer is located within the projection of the second hole opened on the first electrode layer, so that the cutoff boundary layer covering the through groove can be exposed in the second hole. In a specific embodiment, Fig.10 is a schematic diagram of a structure for manufacturing a first electrode provided by an embodiment of the present invention, such as Fig.10As shown, a plurality of first electrodes 210 can be obtained after the first electrode layer 200 is divided by the second hole 220, and the plurality of first electrodes 210 can be arranged the same or different according to actual needs; the second hole 220 can be obtained by etching the first electrode layer 200, and the second hole 220 penetrates the first electrode layer 200, so that a part of the surface of the piezoelectric layer 300 is exposed in the second hole 220, and the side of the cut-off boundary layer 600 in the through groove 320 away from the bonding contact layer 700 is exposed from one of the second holes 220; after etching the second hole 220, the first electrode layer 200 is divided into a plurality of first electrodes 210 by the second hole 220, as shown in FIG. Fig.10 As shown, the number of the second holes 220 may be three, and the number of the second electrodes 410 may be two accordingly.

[0042] like Fig.10 , the plurality of first electrodes 210 correspond to the plurality of piezoelectric bodies 310 one by one, the plurality of piezoelectric bodies 310 correspond to the plurality of second electrodes 410 one by one, in the stacking direction of the resonator, the corresponding projections of the first electrodes 210, the projections of the piezoelectric bodies 310 and the projections of the second electrodes 410 at least partially overlap, and the overlapping parts of the three form an effective area of ​​the resonator, so that the first electrode 210 and the second electrode 410 form an electric field and excite the piezoelectric body 310, and the piezoelectric body 310 generates mechanical vibration under the action of the electric field to achieve the propagation of sound waves. The length of the effective area can affect the efficiency of sound wave excitation and propagation, as well as maximize the utilization of the electric field, reduce energy loss and improve the overall performance of the resonator.

[0043] Specifically, some resonators will be packaged in the filter housing through wafer-level packaging on the side of the first electrode layer away from the piezoelectric layer. After packaging, each first electrode is enclosed between the side of the piezoelectric layer and the filter housing to form a cavity for the first electrode to deform. Choosing WLP (Wafer-Level Packaging) packaging can improve the reliability of the packaging process, and by reducing the length of the electrical path, it can reduce inductance and resistance to improve electrical performance. In order to facilitate WLP packaging of each layer structure, such as Fig.10 As shown, in a specific embodiment, the surface of the cut-off boundary layer 600 located in the through groove 320 facing away from the bonding contact layer 700 is flush with the surface of the piezoelectric layer 300 facing away from the second electrode layer 400. Setting the two surfaces flat means improving the surface flatness, which can ensure uniform deposition of multiple layers of materials in the subsequent wafer packaging process, avoiding inconsistent performance or performance defects due to uneven thickness; in addition, surface flatness can reduce stress concentration, thereby reducing reliability stability such as material cracking caused by stress concentration; and a flat surface helps to improve the yield of the manufacturing process, can reduce rework and scrap caused by surface defects, and thus reduce production costs.

[0044] Before step S7 , the method for manufacturing the resonator further includes: providing a packaging substrate 800 , and bonding the packaging substrate 800 to the bonding contact layer 700 .

[0045] In a specific embodiment, a packaging substrate 800 is provided, and the packaging substrate 800 is bonded to the bonding contact layer 700, and then the product is rotated upside down so that the packaging substrate 800 becomes the base, and the supporting substrate 100 is removed. For details, please refer to Figure 8-Figure 9 .

[0046] Before step S8, the method for manufacturing the resonator further includes: A plurality of third holes 330 are formed on each of the piezoelectric bodies 310 , wherein the plurality of third holes 330 penetrate the piezoelectric body 310 , so that a portion of the surface of the second electrode 410 corresponding to the piezoelectric body 310 is exposed from the third holes 330 ; Manufacturing a plurality of first conductive structures 900 , wherein the first conductive structures 900 correspond to the first electrodes 210 one by one, and the first conductive structures 900 cover a portion of the surface of the corresponding first electrode 210 that is away from the piezoelectric body 310 ; A plurality of second conductive structures 910 are manufactured. The second conductive structures 910 correspond to the third holes 330 one by one. The second conductive structures 910 cover the inner sidewalls of the corresponding third holes 330 and extend to cover the second electrodes 410 exposed in the third holes 330 .

[0047] In a specific embodiment, Fig.11 is a schematic diagram of the structure of etching the third hole provided by an embodiment of the present invention, such as Figure 4 and Fig.11 First, a through groove 320 is etched on the side of the piezoelectric layer 300 away from the first electrode layer to obtain a plurality of piezoelectric bodies 310, and then a third hole 330 is etched through each piezoelectric body 310 on the side of each piezoelectric body 310 away from the second electrode, so that a portion of the surface of the second electrode 410 corresponding to the piezoelectric body 310 is exposed from the third hole 330, so as to allow the subsequent manufacture of a second conductive structure to lead out the electrical signal of the second electrode.

[0048] Further, Fig.12 is a schematic diagram of a structure for forming a conductive structure provided by an embodiment of the present invention, such as Fig.12As shown, a first conductive structure 900 corresponding to the first electrode 210 and a second conductive structure 910 corresponding to the third hole 330 are respectively manufactured. The first conductive structure 900 can be formed on a portion of the surface of the first electrode 210 away from the piezoelectric body 310 by deposition and etching, and the second conductive structure 910 is formed on the inner wall of the third hole 330 and the second electrode 410 exposed in the third hole 330. The first conductive structure 900 and the second conductive structure 910 are used to realize electrical connection with other components.

[0049] S8: For each second electrode 410 , at least one protrusion 510 connected to the second electrode 410 is removed, so that at least one cavity 530 is formed between the side of each second electrode 410 facing away from the piezoelectric layer 300 and the cut-off boundary layer 600 .

[0050] In a specific embodiment, at least one protrusion 510 connected to the second electrode 410 is etched for each second electrode 410 to form the at least one cavity 530 between the side of each second electrode 410 facing away from the piezoelectric layer 300 and the cut-off boundary layer 600 .

[0051] The type of the etching liquid can be determined according to the material of the protrusion 510. During the release of the etching liquid, it is necessary to selectively etch a portion of the sacrificial layer 500 while remaining relatively inert to the materials of other structures. Fig.13 is a schematic diagram of a structure in which a cavity is formed after a portion of the sacrificial layer is corroded according to an embodiment of the present invention. Fig.13 , the etching liquid used to etch the protrusion 510 is injected through the release hole 340, so that for each second electrode 410, at least one protrusion 510 connected to the second electrode 410 is etched, so that each second electrode 410 can form a cavity 530 between the side away from the piezoelectric layer 300 and the cut-off boundary layer 600. In addition, after the etching is completed, each second electrode 410 is connected to a protrusion 510, and the protrusion 510 and the cut-off boundary layer 600 at the corresponding position form a support structure, which together play a supporting role to disperse the stress generated when the resonator is compressed, and solve the problem of excessive stress in a single support.

[0052] In a specific embodiment, the release holes 340 may be etched before the conductive structure is manufactured. The position where the projection of the first electrode 210 overlaps with the projection of the second electrode 410 forms a resonance zone, each piezoelectric body 310 corresponds to a resonance zone, and the piezoelectric body 310 is uniformly etched with release holes 340 at the corresponding position between the outer edge of the resonance zone and the edge of the sacrificial layer 500. The release holes 340 are used to inject etching liquid to achieve etching of part of the protrusion 510 in the sacrificial layer 500, thereby forming a cavity 530.

[0053] An embodiment of the present invention further provides a resonator, the resonator comprising: A first electrode layer 200, a piezoelectric layer 300 and a second electrode layer 400 are stacked; The first electrode layer 200 is provided with second holes 220 to form a plurality of first electrodes 210 disposed at intervals; the second electrode layer 400 is provided with first holes 420 to form a plurality of second electrodes 410 disposed at intervals; The piezoelectric layer 300 is provided with a through groove 320 on one side away from the second electrode layer 400 to form a plurality of piezoelectric bodies 310 arranged at intervals. The through groove 320 is located between two adjacent first electrodes 210 and also between two adjacent second electrodes 410. A sacrificial layer 500 is further disposed on a surface of the second electrode layer 400 facing away from the piezoelectric layer 300, wherein the sacrificial layer 500 includes a plurality of convex portions 510 disposed at intervals, and a groove 520 is formed between two adjacent convex portions 510, and the through groove 320 is connected to one of the grooves 520, wherein each of the second electrodes 410 is connected to at least two convex portions 510; A cut-off boundary layer 600 is provided on the side of the sacrificial layer 500 away from the piezoelectric layer 300, and the cut-off boundary layer 600 covers the side of the protrusion 510 away from the piezoelectric layer 300, the wall surface of the groove 520, the wall surface of the through groove 320, and the second electrode 410 and the piezoelectric body 310 exposed at the groove 520; A bonding contact layer 700 is disposed on one side of the cut-off boundary layer 600 away from the sacrificial layer 500 , and the bonding contact layer 700 fills each of the grooves 520 and covers the surface of the cut-off boundary layer 600 away from the sacrificial layer 500 ; After the bonding contact layer 700 is formed, at least one protrusion 510 connected to the second electrode 410 is removed from each second electrode 410 , so that at least one cavity 530 is formed between the side of each second electrode 410 facing away from the piezoelectric layer 300 and the cutoff boundary layer 600 .

[0054] In some possible embodiments, a surface of the cut-off boundary layer 600 in the through groove 320 facing away from the bonding contact layer 700 is flush with a surface of the piezoelectric layer 300 facing away from the second electrode layer 400 .

[0055] In some possible embodiments, the multiple first electrodes 210 correspond one-to-one to the multiple piezoelectric bodies 310, and the multiple piezoelectric bodies 310 correspond one-to-one to the multiple second electrodes 410. In the stacking direction of the resonator, the corresponding projections of the first electrodes 210, the projections of the piezoelectric bodies 310, and the projections of the second electrodes 410 at least partially overlap.

[0056] In some possible embodiments, the resonator further includes: a plurality of first conductive structures 900 , wherein the first conductive structures 900 correspond to the first electrodes 210 one by one, and the first conductive structures 900 cover a portion of the surface of the corresponding first electrode 210 away from the piezoelectric body 310 ; A plurality of second conductive structures 910, wherein the first conductive structures 900 and the second electrodes 410 correspond one to one, and a third hole 330 penetrating the piezoelectric body 310 is provided on a side of each piezoelectric body 310 away from the second electrode 410, and the second electrode 410 corresponding to the piezoelectric body 310 is exposed in the third hole 330, and the second conductive structure 910 covers the inner side wall of the corresponding third hole 330 and covers the second electrode 410 exposed in the third hole 330.

[0057] In some possible embodiments, the piezoelectric body 310 is further provided with a release hole 340 penetrating the piezoelectric body 310 , so that the etching liquid can be injected through the release hole 340 and corrode the protrusion 510 .

[0058] The present invention further discloses a bulk acoustic wave filter, which includes the resonator as described in any of the above embodiments, and the resonator included in the bulk acoustic wave filter is manufactured by the resonator manufacturing method as described in any of the above embodiments.

[0059] It can be seen from the embodiments provided by the present invention that in the resonator manufacturing method disclosed by the present invention, after a first hole is etched through the second electrode layer so that part of the surface of the piezoelectric layer is exposed through the first hole, a through groove is etched through the piezoelectric layer on the exposed part of the surface of the piezoelectric layer, and the through groove can divide the piezoelectric layer into multiple piezoelectric bodies so that the stress of the piezoelectric layer can be redistributed, thereby reducing local stress, reducing stress concentration and achieving uniform distribution of stress on multiple piezoelectric bodies; in addition, after the through groove is etched on the piezoelectric layer and the sacrificial layer is made, a cut-off boundary layer is made so that at least part of the piezoelectric layer is in contact with the cut-off boundary layer, and the provision of the through groove can enable the piezoelectric layer to adapt to the deformation of the cut-off boundary layer, thereby better adapting to thermal expansion and contraction, and reducing the stress mismatch between the two; at the same time, the through groove provides space to alleviate the thermal stress caused by the difference in thermal expansion coefficient caused by the difference between the material of the piezoelectric layer and the material of the cut-off boundary layer, thereby reducing the stress mismatch between the two. Furthermore, since through-groove etching is performed after etching the first hole, the piezoelectric layer is divided into multiple piezoelectric bodies to reduce the stress of the piezoelectric layer. This can reduce wafer bending due to excessive stress or uneven stress, thereby avoiding the impact of wafer bending on the manufacturing accuracy and quality of the resonator.

[0060] It should be noted that various embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The choice of terms used in this article is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for manufacturing a resonator, characterized in that: The method comprises: The first electrode layer, the piezoelectric layer and the second electrode layer are sequentially stacked; Making a first hole on the second electrode layer, wherein the first hole penetrates the second electrode layer so that a portion of the surface of the piezoelectric layer is exposed in the first hole, and the first hole divides the second electrode layer into a plurality of second electrodes; A through groove is made on the exposed surface of the piezoelectric layer, the through groove penetrates the piezoelectric layer and divides the piezoelectric layer into a plurality of piezoelectric bodies, and a portion of the surface of the first electrode layer is exposed in the through groove, and the through groove is located between two adjacent second electrodes; Making a second hole on the first electrode layer, wherein the second hole penetrates the first electrode layer so that a portion of the surface of the piezoelectric layer is exposed at the second hole, and the second hole divides the first electrode layer into a plurality of first electrodes; For each of the second electrodes, at least one protrusion connected to the second electrode is removed, so that at least one cavity is formed between a side of each of the second electrodes facing away from the piezoelectric layer and the cutoff boundary layer.

2. The method for manufacturing a resonator according to claim 1, characterized in that: After forming the through groove on the exposed surface of the piezoelectric layer, the method further comprises: A sacrificial layer is made on the side of the second electrode layer away from the piezoelectric layer, the sacrificial layer includes a plurality of spaced-apart protrusions, and a groove is formed between two adjacent protrusions, the through groove is exposed in one of the grooves, wherein each of the second electrodes is connected to at least two protrusions.

3. The method for manufacturing a resonator according to claim 2, characterized in that: After manufacturing the sacrificial layer, the method further comprises: The cut-off boundary layer is manufactured, and the cut-off boundary layer covers the side of the protrusion away from the piezoelectric layer, the wall surface of the groove, the wall surface of the through groove, and covers the second electrode and the piezoelectric body exposed at the groove and the first electrode layer exposed at the through groove; A bonding contact layer is manufactured, which fills each groove and the through groove respectively and covers a side of the cut-off boundary layer away from the sacrificial layer; a side of the cut-off boundary layer in the through groove away from the bonding contact layer is exposed from the second hole.

4. The method for manufacturing a resonator according to claim 3, characterized in that: A surface of the cut-off boundary layer in the through groove facing away from the bonding contact layer is flush with a surface of the piezoelectric layer facing away from the second electrode layer.

5. The method for manufacturing a resonator according to claim 1, characterized in that: Before forming a plurality of second holes on the first electrode layer, the method comprises: A packaging substrate is provided, and the packaging substrate is bonded to the bonding contact layer.

6. The method for manufacturing a resonator according to claim 1, characterized in that: The multiple first electrodes correspond to the multiple piezoelectric bodies one by one, and the multiple piezoelectric bodies correspond to the multiple second electrodes one by one. In the stacking direction of the resonator, the corresponding projections of the first electrodes, the projections of the piezoelectric bodies, and the projections of the second electrodes at least partially overlap.

7. The method for manufacturing a resonator according to claim 6, characterized in that: The method further comprises: Making a plurality of third holes on each of the piezoelectric bodies, wherein the plurality of third holes penetrate the piezoelectric body so that a portion of the surface of the second electrode corresponding to the piezoelectric body is exposed from the third holes; Manufacturing a plurality of first conductive structures, wherein the first conductive structures correspond to the first electrodes one by one, and the first conductive structures cover a portion of the surface of the corresponding first electrode facing away from the piezoelectric body; A plurality of second conductive structures are manufactured, wherein the second conductive structures correspond to the third holes one by one, and the second conductive structures cover the inner sidewalls of the corresponding third holes and extend to cover the second electrodes exposed in the third holes.

8. The method for manufacturing a resonator according to claim 1, characterized in that: The method of removing at least one protrusion connected to each second electrode so as to form at least one cavity between a side of each second electrode facing away from the piezoelectric layer and the cut-off boundary layer comprises: The piezoelectric body is provided with a release hole that penetrates the piezoelectric body. The etching liquid is injected through the release hole to corrode at least one protrusion connected to the second electrode for each second electrode, so as to form the at least one cavity between the side of each second electrode away from the piezoelectric layer and the cut-off boundary layer.

9. A resonator, characterized in that: include: A first electrode layer, a piezoelectric layer and a second electrode layer are stacked; The first electrode layer is provided with second holes to form a plurality of first electrodes arranged at intervals; The second electrode layer is provided with a first hole to form a plurality of second electrodes arranged at intervals; A through groove is formed on the side of the piezoelectric layer away from the second electrode layer to form a plurality of piezoelectric bodies arranged at intervals, and the through groove is located between two adjacent first electrodes and also between two adjacent second electrodes; For each of the second electrodes, at least one protrusion connected to the second electrode is removed, so that at least one cavity is formed between a side of each of the second electrodes facing away from the piezoelectric layer and the cutoff boundary layer.

10. A resonator according to claim 9, characterized in that: A sacrificial layer is also provided on the surface of the second electrode layer facing away from the piezoelectric layer. The sacrificial layer includes a plurality of protrusions arranged at intervals, and a groove is formed between two adjacent protrusions. The through groove is connected to one of the grooves, wherein each of the second electrodes is connected to at least two protrusions.

11. A resonator according to claim 10, characterized in that: The cut-off boundary layer is disposed on the side of the sacrificial layer away from the piezoelectric layer, and the cut-off boundary layer covers the side of the protrusion away from the piezoelectric layer, the wall surface of the groove, the wall surface of the through groove, and the second electrode and the piezoelectric body exposed at the groove; A bonding contact layer is provided on the side of the cut-off boundary layer away from the sacrificial layer, and the bonding contact layer fills each of the grooves and covers the surface of the side of the cut-off boundary layer away from the sacrificial layer; the side of the cut-off boundary layer in the through groove away from the bonding contact layer is exposed from the second hole.

12. A resonator according to claim 11, characterized in that: A surface of the cut-off boundary layer in the through groove facing away from the bonding contact layer is flush with a surface of the piezoelectric layer facing away from the second electrode layer.

13. A resonator according to claim 9, characterized in that: The plurality of first electrodes correspond one-to-one to the plurality of piezoelectric bodies, and the plurality of piezoelectric bodies correspond one-to-one to the plurality of second electrodes. In the stacking direction of the resonator, the corresponding projections of the first electrodes, the piezoelectric bodies, and the second electrodes at least partially overlap.

14. A resonator according to claim 13, characterized in that: The resonator further comprises: a plurality of first conductive structures, wherein the first conductive structures correspond to the first electrodes one by one, and the first conductive structures cover a portion of a surface of the corresponding first electrode that is away from the piezoelectric body; A plurality of second conductive structures, wherein the first conductive structure and the second electrode correspond one to one, a third hole penetrating the piezoelectric body is provided on a side of each piezoelectric body away from the second electrode, the second electrode corresponding to the piezoelectric body is exposed in the third hole, and the second conductive structure covers the inner side wall of the corresponding third hole and covers the second electrode exposed in the third hole.

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