A method for manufacturing a resonator and a resonator

Abstract

The present invention discloses a method for manufacturing a resonator and a resonator, comprising: sequentially stacking a first electrode layer, a piezoelectric layer, and a second electrode layer; making a first hole penetrating the second electrode layer to obtain a plurality of second electrodes, with a portion of the surface of the piezoelectric layer exposed at the first hole; making a through groove on the exposed surface of the piezoelectric layer to obtain a plurality of piezoelectric bodies, with the through groove located between two second electrodes; making a sacrificial layer comprising a plurality of protrusions, with two adjacent protrusions forming a groove, with the through groove exposed at the groove; making a cutoff boundary layer to cover one side of the protrusion, the wall of the groove, the wall of the through groove, a portion of the second electrode, a portion of the piezoelectric body, and a portion of the first electrode layer; making a second hole penetrating the first electrode layer to obtain a plurality of first electrodes, with a portion of the surface of the piezoelectric layer exposed at the second hole, and a portion of the cutoff boundary layer exposed from the second hole; and removing the protrusions corresponding to the second electrode to form a cavity. The above method can reduce the stress mismatch between the cutoff boundary layer and the piezoelectric layer.

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 the 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] As an important component of the bulk acoustic wave filter, the resonator in the existing technology generates large stress in the resonator manufacturing process because 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 the material and manufacturing process 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 cutoff 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 the resonator are provided, comprising:

[0007] stacking a first electrode layer, a piezoelectric layer, and a second electrode layer in sequence;

[0008] 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;

[0009] A through groove is formed 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;

[0010] A second hole is formed 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 located in the through groove facing away from the bonding contact layer is exposed in the second hole;

[0011] 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.

[0012] In some possible embodiments, after forming the through groove on the exposed surface of the piezoelectric layer, the method further includes:

[0013] A sacrificial layer is made on the side 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 exposed in one of the grooves, wherein each of the second electrodes is connected to at least two protrusions.

[0014] In some possible embodiments, after forming the sacrificial layer, the method further includes:

[0015] Producing a cutoff boundary layer, wherein the cutoff 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;

[0016] A bonding contact layer is fabricated, which fills each groove and the through groove and covers the side of the cutoff boundary layer away from the sacrificial layer; the side of the cutoff 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 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.

[0018] In some possible embodiments, before forming the plurality of second holes on the first electrode layer, the method includes:

[0019] A packaging substrate is provided, and the packaging substrate is bonded to the bonding contact layer.

[0020] 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.

[0021] In some possible embodiments, the method further includes:

[0022] 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;

[0023] Fabricating a plurality of first conductive structures, each of the first conductive structures corresponding to the first electrodes one by one, and each of the first conductive structures covering a portion of a surface of the corresponding first electrode facing away from the piezoelectric body;

[0024] A plurality of second conductive structures are manufactured, each of the second conductive structures corresponding to the third holes. 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.

[0025] In some possible embodiments, 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 includes:

[0026] The piezoelectric body is provided with a release hole that passes through the piezoelectric body, and 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 facing away from the piezoelectric layer and the cut-off boundary layer.

[0027] According to a second aspect of the present disclosure, a resonator is provided, comprising:

[0028] A first electrode layer, a piezoelectric layer, and a second electrode layer are stacked;

[0029] The first electrode layer is provided with second holes to form a plurality of first electrodes spaced apart from each other; the second electrode layer is provided with first holes to form a plurality of second electrodes spaced apart from each other;

[0030] A through groove is formed on the side of the piezoelectric layer facing 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;

[0031] 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.

[0032] 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.

[0033] In some possible embodiments, a cutoff boundary layer is provided on a side of the sacrificial layer facing 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;

[0034] A bonding contact layer is provided on the side of the cut-off boundary layer facing away from the sacrificial layer, and the bonding contact layer fills each of the grooves and covers the surface of the cut-off boundary layer facing away from the sacrificial layer; the side of the cut-off boundary layer in the through groove facing away from the bonding contact layer is exposed from the second hole.

[0035] In some possible embodiments, 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.

[0036] 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.

[0037] In some possible embodiments, the resonator further includes:

[0038] a plurality of first conductive structures, each of the first conductive structures corresponding to the first electrodes one by one, and covering a portion of a surface of the corresponding first electrode facing away from the piezoelectric body;

[0039] Multiple second conductive structures, the first conductive structure and the second electrode correspond one to one, a third hole penetrating the piezoelectric body is opened on the 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 wall of the corresponding third hole and covers the second electrode exposed in the third hole.

[0040] The implementation of the present invention has the following beneficial effects:

[0041] In the resonator manufacturing method disclosed in 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. 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 stress distribution on multiple piezoelectric bodies; in addition, after the through groove is etched on the piezoelectric layer and the sacrificial layer is made, the through groove is exposed in the groove formed by the two protrusions. At this time, a cut-off boundary layer is made, which can cover the wall of the through groove and the piezoelectric layer exposed at the through groove. Such a setting can make the piezoelectric layer 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, thereby reducing the stress of the piezoelectric layer. Therefore, it is possible to reduce the bending of the wafer 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

[0042] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. 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.

[0043] Figure 1 A schematic flow chart corresponding to a method for manufacturing a resonator provided in an embodiment of the present invention;

[0044] Figure 2 Schematic diagram of a sandwich structure constructed on a supporting substrate according to an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the structure of manufacturing the second electrode provided by an embodiment of the present invention;

[0046] Figure 4 is a schematic structural diagram of manufacturing a piezoelectric body provided by an embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of a structure for fabricating a sacrificial layer on a second electrode layer according to an embodiment of the present invention;

[0048] Figure 6 This is a schematic diagram of the structure of producing a cutoff boundary layer provided by an embodiment of the present invention;

[0049] Figure 7 It is a structural diagram of manufacturing a bonding contact layer provided by an embodiment of the present invention;

[0050] Figure 8 Schematic diagram of the structure of bonding between a packaging substrate and a bonding contact layer provided by an embodiment of the present invention;

[0051] Figure 9 This is a schematic diagram of a structure in which a supporting substrate is removed according to an embodiment of the present invention;

[0052] Figure 10 This is a schematic structural diagram of manufacturing a first electrode according to an embodiment of the present invention;

[0053] Figure 11 is a schematic structural diagram of etching a third hole according to an embodiment of the present invention;

[0054] Figure 12 is a schematic structural diagram of forming a conductive structure provided by an embodiment of the present invention;

[0055] Figure 13 It is a structural schematic diagram of a cavity formed after a portion of the sacrificial layer is corroded, provided by an embodiment of the present invention.

[0056] The accompanying drawings are numerals as follows:

[0057] 100-support substrate;

[0058] 200-first electrode layer, 210-first electrode, 220-second hole;

[0059] 300 - piezoelectric layer, 310 - piezoelectric body, 320 - through groove, 330 - third hole, 340 - release hole;

[0060] 400 - second electrode layer, 410 - second electrode, 420 - first hole;

[0061] 500-sacrificial layer, 510-protrusion, 520-groove, 530-cavity;

[0062] 600-cutoff boundary layer;

[0063] 700-bonding contact layer;

[0064] 800-Packaging substrate;

[0065] 900 - first conductive structure, 910 - second conductive structure. DETAILED DESCRIPTION

[0066] 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 embodiments described 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 making any creative efforts are within the scope of protection of this invention.

[0067] It should be noted that the terms "first", "second", etc. in the description 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 numbers used in this way are 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.

[0068] 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 indicated.

[0069] 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.

[0070] The term "and / or" as used herein describes an association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can represent the existence of A alone, the simultaneous existence of A and B, and the existence of B alone. Furthermore, the term "at least one" as used herein refers to any combination of at least two of any one or more of a plurality of items. For example, "at least one of A, B, and C" can represent any one or more elements selected from the set consisting of A, B, and C.

[0071] In addition, numerous specific details are provided in the following detailed description to better illustrate the present disclosure. Those skilled in the art will appreciate that the present disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art are not described in detail in order to highlight the main points of the present disclosure.

[0072] Figure 1This is a flow chart 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:

[0073] S1: stacking a first electrode layer 200, a piezoelectric layer 300 and a second electrode layer 400 in sequence;

[0074] In a specific embodiment, Figure 2 This is 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 relatively thin 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.

[0075] 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.

[0076] S2: forming 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 ;

[0077] In a specific embodiment, Figure 3 Schematic diagram of the structure of the second electrode provided by the embodiment of the present invention; Figure 3As shown, a plurality of second electrodes 410 can be obtained by dividing the second electrode layer 400 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 passes through 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.

[0078] It should be noted that the present invention uses the manufacturing process of two resonators as an example for description. Therefore, the number of first holes 420 can be one, and the number of second electrodes 410 can be two. In actual application, the number of first holes 420 can be set based on actual needs, and the number of second electrodes 410 can be changed accordingly. In addition, the number of second holes 220, third holes 330, release holes 340, protrusions 510, through-slots 320, and cavities 530 mentioned below can also be set based on actual needs, and the number of first electrodes 210, piezoelectric bodies 310, and grooves 520 can also be changed accordingly.

[0079] S3: forming 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;

[0080] In a specific embodiment, since the structure of the piezoelectric layer 300 itself has stress, and the differences in materials and thermal expansion coefficients between the layers of the structure will also produce large stress, after the first hole 420 is etched 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 is made on the exposed surface of the piezoelectric layer 300 to pass through the piezoelectric layer 300 to reduce the stress in the piezoelectric layer 300 itself.

[0081] Figure 4 Schematic diagram of the structure of manufacturing a piezoelectric body according to an embodiment of the present invention; Figure 4 As shown, the setting of the through groove 320 can divide the piezoelectric layer 300 into multiple piezoelectric bodies 310. The number of the multiple piezoelectric bodies 310 can be two, and the lengths of the multiple 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 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 the two adjacent piezoelectric bodies 310.

[0082] The provision of the through-grooves 320 can provide space to alleviate thermal stress caused by the difference in thermal expansion coefficients between the material of the piezoelectric layer 300 and the materials of other layers, thereby reducing the stress mismatch between the piezoelectric layer 300 and other layers. Furthermore, because the through-grooves 320 are etched after the first holes 420 are etched, the piezoelectric layer 300 is divided into multiple piezoelectric bodies 310 and the stress of the piezoelectric layer 300 is reduced. This can reduce the risk of wafer bowing due to excessive or uneven stress, thereby preventing the impact of wafer bowing on the manufacturing accuracy and quality of the resonator.

[0083] S4: forming a sacrificial layer 500 on a side of the second electrode layer 400 facing away from the piezoelectric layer 300 , wherein the sacrificial layer 500 includes a plurality of spaced-apart protrusions 510 , with grooves 520 formed between two adjacent protrusions 510 , and the through-slot 320 exposed in one of the grooves 520 , wherein each second electrode 410 is connected to at least two protrusions 510 ;

[0084] 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 sacrificial layer 500 can be etched to form a cavity 530, so that the cavity 530 is used to achieve the propagation or resonance of sound waves.

[0085] Specifically, Figure 5 FIG. 1 is a schematic diagram of a structure in which a sacrificial layer is formed 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 to form a plurality of spaced-apart protrusions 510 on the sacrificial layer 500, and a groove 520 is formed between two adjacent protrusions 510. Among the multiple 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 5Each 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 facing 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 facing away from the piezoelectric body 310.

[0086] S5: forming a cutoff boundary layer 600, wherein the cutoff 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 in the groove 520 and the first electrode layer 200 exposed in the through groove 320;

[0087] In a specific embodiment, Figure 6 Schematic diagram of the structure of the cut-off boundary layer provided by the embodiment of the present invention. 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, the second electrode 410 and the piezoelectric body 310 exposed in the groove 520, and the first electrode layer 200 exposed in the through-groove 320. The material of the cut-off boundary layer 600 can be any material that is resistant to 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.

[0088] S6: forming a bonding contact layer 700 , wherein the bonding contact layer 700 fills each groove 520 and the through groove 320 , and covers a side of the cutoff boundary layer 600 away from the sacrificial layer 500 ;

[0089] In a specific embodiment, Figure 7 FIG. 1 is a schematic diagram of a structure for making a bonding contact layer according to an embodiment of the present invention. Figure 7As shown, the bonding contact layer 700 can be fabricated by deposition so that the bonding contact layer 700 can fill each groove 520 and through-groove 320, and cover the side of the cut-off boundary layer 600 away from the sacrificial layer 500. Furthermore, the side of the bonding contact layer 700 away from the cut-off boundary layer 600 is polished, preferably using chemical mechanical polishing (CMP), to make the side of the bonding contact layer away from the cut-off boundary layer 600 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, phosphosilicate glass, and silicon nitride. The material selection can also be based on specific needs.

[0090] S7: A second hole 220 is made on the first electrode layer 200. 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. The second hole 220 divides the first electrode layer 200 into a plurality of first electrodes 210. The cutoff boundary layer 600 located in the through groove 320 is exposed from the second hole 220 on the side facing 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, Figure 10 Schematic diagram of the structure of the first electrode provided by the embodiment of the present invention, such as Figure 10 As shown, a plurality of first electrodes 210 can be obtained by dividing the first electrode layer 200 by the second hole 220. 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. The second hole 220 passes through 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 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. Figure 10 As shown, the number of the second holes 220 may be three, and the number of the second electrodes 410 is correspondingly two.

[0091] like Figure 10The plurality of first electrodes 210 correspond one-to-one with the plurality of piezoelectric bodies 310, and the plurality of piezoelectric bodies 310 correspond one-to-one with the plurality of 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. The overlapping portion of the three forms the effective area of ​​the resonator, so that the first electrodes 210 and the second electrodes 410 form an electric field and excite the piezoelectric bodies 310. The piezoelectric bodies 310 generate mechanical vibrations under the action of the electric field, thereby achieving the propagation of sound waves. The length of the effective area can affect the efficiency of sound wave excitation and propagation, maximize electric field utilization, reduce energy loss, and improve the overall performance of the resonator.

[0092] Specifically, some resonators will subsequently be packaged in a filter housing through wafer-level packaging on the side of the first electrode layer facing away from the piezoelectric layer. After packaging, each first electrode will be enclosed between the side facing away from 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 Figure 10 As shown, in a specific embodiment, the surface of the cutoff 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. Providing these two surfaces with a flush surface improves surface flatness, ensuring uniform deposition of multiple layers of material during subsequent wafer packaging, avoiding inconsistent performance or defects due to uneven thickness. Furthermore, a flat surface reduces stress concentration, thereby minimizing material cracking caused by stress concentration and improving reliability. Furthermore, a flat surface helps improve the yield of the manufacturing process, reducing rework and scrap due to surface defects, thereby reducing production costs.

[0093] Before step S7 , the resonator manufacturing method further includes: providing a packaging substrate 800 , and bonding the packaging substrate 800 to the bonding contact layer 700 .

[0094] 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 .

[0095] Before step S8, the resonator manufacturing method further includes:

[0096] 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 ;

[0097] Fabricate a plurality of first conductive structures 900 , wherein each of the first conductive structures 900 corresponds to the first electrodes 210 one by one, and each of the first conductive structures 900 covers a portion of the surface of the corresponding first electrode 210 facing away from the piezoelectric body 310 ;

[0098] A plurality of second conductive structures 910 are fabricated. Each of the second conductive structures 910 corresponds 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 .

[0099] In a specific embodiment, Figure 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 Figure 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 part of the surface of the second electrode 410 corresponding to the piezoelectric body 310 is exposed from the third hole 330, which is used for the subsequent production of a second conductive structure to lead out the electrical signal of the second electrode.

[0100] Further, Figure 12 Schematic diagram of the structure of the conductive structure provided by the embodiment of the present invention, such as Figure 12 As 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 separately fabricated. Deposition and etching can be used to form the first conductive structure 900 on a portion of the surface of the first electrode 210 facing away from the piezoelectric body 310, and the second conductive structure 910 is formed on the inner sidewall of the third hole 330 and on the second electrode 410 exposed within the third hole 330. The first conductive structure 900 and the second conductive structure 910 are used to achieve electrical connection with other components.

[0101] S8: For each second electrode 410 , remove at least one protrusion 510 connected to the 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 cut-off boundary layer 600 .

[0102] In a specific embodiment, at least one protrusion 510 connected to each second electrode 410 is etched 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 cutoff boundary layer 600 .

[0103] 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. Figure 13 FIG. 1 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. Figure 13 The etching solution used to etch the protrusions 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, thereby forming a cavity 530 between the side of each second electrode 410 facing away from the piezoelectric layer 300 and the cut-off boundary layer 600. In addition, after etching, each second electrode 410 is connected to a protrusion 510. 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, thereby solving the problem of excessive stress in a single support.

[0104] In a specific embodiment, the release holes 340 can be etched before forming the conductive structure. The location where the projection of the first electrode 210 overlaps with the projection of the second electrode 410 forms a resonance region. Each piezoelectric body 310 corresponds to a resonance region. The piezoelectric body 310 is uniformly etched with release holes 340 at corresponding locations between the outer edge of the resonance region and the edge of the sacrificial layer 500. The release holes 340 are used to inject etching liquid to etch a portion of the raised portion 510 in the sacrificial layer 500, thereby forming a cavity 530.

[0105] An embodiment of the present invention further provides a resonator, comprising:

[0106] A first electrode layer 200, a piezoelectric layer 300, and a second electrode layer 400 are stacked;

[0107] The first electrode layer 200 is provided with second holes 220 to form a plurality of first electrodes 210 spaced apart from each other; the second electrode layer 400 is provided with first holes 420 to form a plurality of second electrodes 410 spaced apart from each other;

[0108] The piezoelectric layer 300 is provided with a through-groove 320 on a side facing away from the second electrode layer 400 to form a plurality of spaced-apart piezoelectric bodies 310. The through-groove 320 is located between two adjacent first electrodes 210 and also between two adjacent second electrodes 410.

[0109] A sacrificial layer 500 is further provided on a surface of the second electrode layer 400 facing away from the piezoelectric layer 300. The sacrificial layer 500 includes a plurality of spaced-apart protrusions 510, with grooves 520 formed between two adjacent protrusions 510. The through-slot 320 is connected to one of the grooves 520. Each second electrode 410 is connected to at least two protrusions 510.

[0110] A cutoff boundary layer 600 is provided on a side of the sacrificial layer 500 away from the piezoelectric layer 300 , and the cutoff boundary layer 600 covers a side of the protrusion 510 away from the piezoelectric layer 300 , a wall surface of the groove 520 , a wall surface of the through-groove 320 , and covers the second electrode 410 and the piezoelectric body 310 exposed in the groove 520 ;

[0111] A bonding contact layer 700 is provided on a side of the cut-off boundary layer 600 facing away from the sacrificial layer 500 , and the bonding contact layer 700 fills each of the grooves 520 and covers a surface of the cut-off boundary layer 600 facing away from the sacrificial layer 500 ;

[0112] After the bonding contact layer 700 is formed, at least one protrusion 510 connected to each 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 .

[0113] 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 .

[0114] 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.

[0115] In some possible embodiments, the resonator further includes:

[0116] a plurality of first conductive structures 900 , each of the first conductive structures 900 corresponding to the first electrodes 210 , and each of the first conductive structures 900 covers a portion of a surface of the corresponding first electrode 210 facing away from the piezoelectric body 310 ;

[0117] Multiple second conductive structures 910, 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 opened on the 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 wall of the corresponding third hole 330 and covers the second electrode 410 exposed in the third hole 330.

[0118] 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 .

[0119] The present invention further discloses a bulk acoustic wave filter, which includes the resonator described in any of the above embodiments, and the resonator included in the filter is manufactured by the resonator manufacturing method described in any of the above embodiments.

[0120] It can be seen from the embodiments provided by the present invention above that in the resonator manufacturing method disclosed by the present invention, after a first hole is etched through the second electrode layer on 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. 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 cutoff boundary layer is made so that at least part of the piezoelectric layer is in contact with the cutoff boundary layer. The provision of the through groove can enable the piezoelectric layer to adapt to the deformation of the cutoff 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 cutoff 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, thereby reducing the stress of the piezoelectric layer. Therefore, it is possible to reduce the bending of the wafer due to excessive stress or uneven stress, thereby avoiding the impact of wafer bending on the manufacturing accuracy and quality of the resonator.

[0121] It should be noted that the various embodiments of the present disclosure have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles, practical applications, or technical improvements to the market of the various embodiments, or to enable other persons skilled in the art to understand the various embodiments disclosed herein.

Claims

1. A method for manufacturing a resonator, characterized in that: The method comprises: stacking a first electrode layer, a piezoelectric layer, and a second electrode layer in sequence; 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 formed 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; Producing a cutoff boundary layer, the cutoff boundary layer covering the side of the protrusion away from the piezoelectric layer, the wall surface of the groove, the wall surface of the through groove, and covering the second electrode and the piezoelectric body exposed at the groove and the first electrode layer exposed at the through groove; 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, wherein: 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 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 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, wherein: After the cutoff boundary layer is formed, the method further comprises: A bonding contact layer is fabricated, which fills each groove and the through groove and covers the side of the cutoff boundary layer away from the sacrificial layer; the side of the cutoff 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, wherein: 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, wherein: 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.

6. The method for manufacturing a resonator according to claim 1, wherein: The multiple first electrodes correspond to the multiple piezoelectric bodies one-to-one, and the multiple piezoelectric bodies correspond to the multiple second electrodes one-to-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, wherein: 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; Fabricating a plurality of first conductive structures, each of the first conductive structures corresponding to the first electrodes one by one, and each of the first conductive structures covering a portion of a surface of the corresponding first electrode facing away from the piezoelectric body; A plurality of second conductive structures are manufactured, each of the second conductive structures corresponding to the third holes. 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, wherein: The step 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 cutoff boundary layer comprises: The piezoelectric body is provided with a release hole that passes through the piezoelectric body, and 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 facing 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 first holes to form a plurality of second electrodes arranged at intervals; A through groove is formed on the side of the piezoelectric layer facing 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; A cutoff boundary layer is provided on a side of the second electrode layer away from the piezoelectric layer, 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; 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 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.

11. A resonator according to claim 10, characterized in that: A bonding contact layer is provided on the side of the cut-off boundary layer facing away from the sacrificial layer, and the bonding contact layer fills each of the grooves and covers the surface of the cut-off boundary layer facing away from the sacrificial layer; the side of the cut-off boundary layer in the through groove facing 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. The resonator according to claim 9, characterized in that: Multiple first electrodes correspond to multiple piezoelectric bodies one-to-one, and the multiple piezoelectric bodies correspond to multiple second electrodes one-to-one. 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, each of the first conductive structures corresponding to the first electrodes one by one, and covering a portion of a surface of the corresponding first electrode facing away from the piezoelectric body; Multiple second conductive structures, the first conductive structure and the second electrode correspond one to one, a third hole penetrating the piezoelectric body is opened on the 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 wall of the corresponding third hole and covers the second electrode exposed in the third hole.

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