A bulk acoustic resonator array, a bulk acoustic filter, and a communication device

Abstract

This invention discloses a bulk acoustic wave (BAW) resonator array, a BAW filter, and a communication device. The BAW resonator array includes at least three BAW resonators, each comprising a stacked structure of a first electrode, a piezoelectric layer, and a second electrode. The at least three BAW resonators are stacked, with the upper BAW resonator positioned above two adjacent lower BAW resonators via a first support layer. The adjacent lower BAW resonators have at least one of a V-shape, a trapezoid, and a parallelogram shape. The technical solution provided by this invention reduces the size of the BAW resonator array, thereby achieving miniaturization of the BAW resonator array, the BAW filter, and the communication device.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a bulk acoustic wave resonator array, a bulk acoustic wave filter, and a communication device. Background Technology

[0002] With the continuous development of wireless communication technology, high-performance, small-sized communication devices are being used more and more widely.

[0003] A bulk acoustic wave resonator group includes at least one film bulk acoustic wave resonator, also known as a bulk acoustic wave (BAS). Due to its small size, high operating frequency, low power consumption, high quality factor, and compatibility with CMOS technology, the BAS resonator has become an important device in the field of communication devices and is widely used.

[0004] The existing bulk acoustic wave resonator arrays are too large, which is not conducive to the miniaturization of bulk acoustic wave resonator arrays, bulk acoustic wave filters and communication devices. Figure 1 This is a schematic diagram of the structure of a bulk acoustic wave filter in the prior art. See also... Figure 1 The bulk acoustic wave filter includes a substrate 001, and the first surface 101 of the substrate 001 includes a bulk acoustic wave resonator group composed of a bulk acoustic wave resonator 21, a bulk acoustic wave resonator 22, and a bulk acoustic wave resonator 23. Each bulk acoustic wave resonator includes a stacked structure of a first electrode 20a, a piezoelectric layer 20b, and a second electrode 20c. In a first aspect, because the bulk acoustic wave resonators 21, 22, and 23 are laid flat on the first surface 101 of the substrate 001, the size of the bulk acoustic wave filter in the thickness direction perpendicular to the substrate 001 is too large, which is detrimental to the miniaturization of the bulk acoustic wave filter and communication devices. Secondly, since the bulk acoustic wave resonators 21, 22, and 23 are laid flat on the first surface 101 of the substrate 001, in order to reduce the acoustic wave loss of the bulk acoustic wave filter, an acoustic reflection structure 40 needs to be provided for each of the bulk acoustic wave resonators 21, 22, and 23 on the surface or inside the substrate 001. This results in a complicated fabrication process and high fabrication cost. In particular, when the acoustic reflection structure 40 includes a cavity structure 40a or a back groove, it will also reduce the structural stability of the bulk acoustic wave filter. It should be noted that the thickness direction parallel to the substrate 001 is the Y direction in the XOY plane rectangular coordinate system, and the thickness direction perpendicular to the substrate 001 is the X direction in the XOY plane rectangular coordinate system. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a bulk acoustic wave resonator group, a bulk acoustic wave filter, and a communication device to reduce the size of the bulk acoustic wave resonator group, thereby achieving miniaturization of the bulk acoustic wave resonator group, the bulk acoustic wave filter, and the communication device.

[0006] This invention provides a bulk acoustic wave resonator group, comprising: at least three bulk acoustic wave resonators, each of the bulk acoustic wave resonators comprising a stacked structure of a first electrode, a piezoelectric layer, and a second electrode;

[0007] The at least three bulk acoustic wave resonators are stacked, with the upper bulk acoustic wave resonator disposed on the two adjacent bulk acoustic wave resonators of the lower layer through a first support layer. The two adjacent bulk acoustic wave resonators of the lower layer are in at least one of the following structures: V-shaped, trapezoidal, and parallelogram.

[0008] Optionally, the lower-layer bulk acoustic resonator includes at least two;

[0009] One end of each of the two bulk acoustic resonators is supported by a V-shaped structure, and the other end is supported by a support structure. The upper bulk acoustic resonator is disposed on the V-shaped space through the first support layer.

[0010] Alternatively, the two bulk acoustic resonators are located on the two sides of the trapezoid via a support structure, and the upper bulk acoustic resonator is disposed on the V-shaped space between the two sides of the trapezoid via the first support layer.

[0011] Alternatively, the two bulk acoustic resonators are located on the parallel sides of a parallelogram via a support structure, and the upper bulk acoustic resonator is disposed on the V-shaped space between the parallel sides of the parallelogram via the first support layer.

[0012] Optionally, the lower layer may include at least four bulk acoustic resonators, and the V-shaped structure formed by two adjacent bulk acoustic resonators in the lower layer may be an inverted V-shaped structure or an upright V-shaped structure.

[0013] The upper-layer bulk acoustic resonator is disposed on the V-shaped space through the first support layer. The V-shaped space is composed of two adjacent upright V-shaped bulk acoustic resonators disposed on the lower layer.

[0014] Optionally, the angle formed by the V-shaped sides of the V-shaped structure is greater than or equal to 0° and less than or equal to 90°.

[0015] Optionally, the two adjacent bulk acoustic resonators in the lower layer support each other in an inverted V-shaped structure;

[0016] Alternatively, the two adjacent bulk acoustic resonators in the lower layer can be arranged in an inverted V-shape under the support of the second support layer.

[0017] Optionally, the electrodes of two adjacent bulk acoustic resonators in the lower layer are electrically connected through an intermediate conductive part;

[0018] Alternatively, the electrodes of two adjacent bulk acoustic resonators in the lower layer can be in direct contact to achieve electrical connection;

[0019] Alternatively, the electrodes of the two adjacent bulk acoustic resonators in the lower layer are insulated.

[0020] Optionally, the bulk acoustic resonator further includes a temperature compensation layer, which comprises a material with a positive frequency drift coefficient.

[0021] Optionally, the temperature compensation layer is located at at least one of the following locations: inside the piezoelectric layer, on the surface of the piezoelectric layer adjacent to the first electrode, on the surface of the piezoelectric layer adjacent to the second electrode, inside the first electrode, on the surface of the first electrode facing away from the piezoelectric layer, inside the second electrode, and on the surface of the second electrode facing away from the piezoelectric layer.

[0022] This invention also provides a bulk acoustic wave filter, including at least one substrate, the substrate including a first surface and a second surface disposed opposite to the first surface, the first surface of the substrate being provided with at least one bulk acoustic wave resonator group as described in any of the above technical solutions;

[0023] The substrate and the lower layer of the bulk acoustic wave resonator group supported by the substrate form a predetermined angle.

[0024] Optionally, the substrate includes an adjacent first substrate and a second substrate;

[0025] The first substrate has at least one bulk acoustic wave resonator group disposed on its first surface, and the second substrate has at least one bulk acoustic wave resonator group disposed on its second surface. The bulk acoustic wave resonator groups between the first substrate and the second substrate are distributed in an interdigitated pattern.

[0026] Optionally, conductive interconnect structures may also be included;

[0027] The conductive interconnect structure is used to lead the electrical signal of the bulk acoustic wave resonator group to the first surface side of the uppermost substrate, and / or, the conductive interconnect structure is used to lead the electrical signal of the bulk acoustic wave resonator group to the second surface side located on the lowermost substrate.

[0028] Optionally, it also includes a wafer cover plate, which is located on the first surface side of the uppermost substrate;

[0029] The conductive interconnect structure is used to direct the electrical signals of the bulk acoustic resonator group to the surface of the wafer cover away from the uppermost substrate.

[0030] Optionally, the first electrode or the second electrode of the bulk acoustic resonator adjacent to the conductive interconnect structure is connected to the conductive interconnect structure via a conductive connection portion.

[0031] Optionally, a first bulk acoustic wave resonator group is disposed on the first surface of the first substrate, the first bulk acoustic wave resonator group including at least two upper-layer bulk acoustic wave resonators.

[0032] The bulk acoustic wave filter further includes a second substrate located on the upper layer of the first substrate, and a second bulk acoustic wave resonator group is disposed on the second surface of the second substrate.

[0033] The upper layer of the second bulk acoustic resonator group is located between the upper layer of the first bulk acoustic resonator group.

[0034] Optionally, in the thickness direction parallel to the substrate, the spacing between adjacent substrates is less than the sum of the heights of the bulk acoustic wave resonator groups that are interdigitated between adjacent substrates.

[0035] Optionally, in the horizontal direction, the two groups of acoustic resonators are spaced apart by a preset distance.

[0036] This invention also provides a communication device, including any of the bulk acoustic wave filters described in the above technical solutions;

[0037] The communication device includes at least one of a filter, a duplexer, and a multiplexer.

[0038] The technical solution provided by this invention has three aspects. First, at least three bulk acoustic wave (BAW) resonators are stacked, reducing the size of the BAW resonator group perpendicular to the stacking direction, which helps to form a miniaturized BAW resonator group. The lower layer of adjacent BAW resonators has at least one of a V-shape, trapezoid, and parallelogram structure, further reducing the size of the BAW resonator group perpendicular to the stacking direction. Second, the V-shape, trapezoid, and parallelogram structures form an air gap structure, which can reflect sound waves back to the adjacent lower and upper BAW resonators, thereby reducing sound wave loss and improving the quality factor of the BAW resonator group. Third, in this invention, the acoustic reflection structure does not need to be set on the substrate by cutting grooves, simplifying the fabrication process, reducing fabrication costs, and also improving the structural stability of the BAW resonator group. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of a bulk acoustic wave filter in the prior art;

[0040] Figure 2This is a schematic diagram of the structure of a bulk acoustic resonator array provided in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of another bulk acoustic resonator array provided in an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of another bulk acoustic resonator array provided in an embodiment of the present invention;

[0043] Figure 5 A schematic diagram of another bulk acoustic resonator array provided in an embodiment of the present invention;

[0044] Figure 6 A schematic diagram of another bulk acoustic resonator array provided in an embodiment of the present invention;

[0045] Figure 7 A schematic diagram of another bulk acoustic resonator array provided in an embodiment of the present invention;

[0046] Figure 8 A schematic diagram of another bulk acoustic resonator array provided in an embodiment of the present invention;

[0047] Figure 9 This is a schematic diagram of the structure of a bulk acoustic wave filter provided in an embodiment of the present invention;

[0048] Figure 10 This is a schematic diagram of another bulk acoustic wave filter provided in an embodiment of the present invention;

[0049] Figure 11 This is a schematic diagram of the structure of another bulk acoustic wave filter provided in an embodiment of the present invention;

[0050] Figure 12 for Figure 9 The equivalent circuit connection diagram of the bulk acoustic wave filter in the image;

[0051] Figure 13 for Figure 6 Flowchart of the fabrication method of the bulk acoustic resonator group in the image;

[0052] Figure 14 for Figure 13 Schematic diagrams of cross-sectional structures corresponding to each step in the fabrication method of the medium-volume acoustic resonator group. Detailed Implementation

[0053] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0054] To address the technical problem that existing bulk acoustic wave resonator arrays are too large, hindering the miniaturization of bulk acoustic wave resonator arrays, bulk acoustic wave filters, and communication devices, embodiments of the present invention provide the following bulk acoustic wave resonator array:

[0055] The bulk acoustic wave resonator group includes: at least three bulk acoustic wave resonators, each of which includes a stacked structure of a first electrode, a piezoelectric layer, and a second electrode; the at least three bulk acoustic wave resonators are stacked, with the upper bulk acoustic wave resonator disposed on top of two adjacent lower bulk acoustic wave resonators through a first support layer, and the two adjacent lower bulk acoustic wave resonators having at least one of the following structures: V-shaped, trapezoidal, and parallelogram-shaped.

[0056] For example, see Figures 2-5 The bulk acoustic wave resonator group includes three bulk acoustic wave resonators: bulk acoustic wave resonator 24, bulk acoustic wave resonator 25, and bulk acoustic wave resonator 26. Each bulk acoustic wave resonator includes a stacked structure of a first electrode 20a, a piezoelectric layer 20b, and a second electrode 20c. The bulk acoustic wave resonators 24, 25, and 26 are stacked, with the upper-layer bulk acoustic wave resonator 26 positioned above the lower-layer two bulk acoustic wave resonators 24 and 25 via a first support layer 30. Figure 2 The two bulk acoustic resonators 24 and 25 in the middle and lower layers have a V-shaped structure. Figure 3 The two bulk acoustic resonators 24 and 25 in the middle and lower layers are trapezoidal. Figure 4 and Figure 5 The two bulk acoustic resonators 24 and 25 in the middle and lower layers are parallelograms.

[0057] The above technical solution reduces the size of the bulk acoustic wave resonator array perpendicular to the stacking direction of the bulk acoustic wave resonators, which helps to form a miniaturized bulk acoustic wave resonator array. It should be noted that, in the embodiments of the present invention, the stacking direction of the bulk acoustic wave resonators is parallel to the Y direction in the XOY coordinate system.

[0058] Optionally, the first support layer 30 can be a conductive support layer or an insulating support layer.

[0059] It should be noted that within a bulk acoustic wave resonator array, electrical connections between different bulk acoustic wave resonators can be achieved through conductive connecting parts of a predetermined shape or through direct contact. For example, Figure 2 In this circuit, the second electrodes 20c of the bulk acoustic resonator 24 and the bulk acoustic resonator 25 are electrically connected through direct contact.

[0060] The technical solution provided by this invention has three aspects. First, at least three bulk acoustic wave (BAW) resonators are stacked, reducing the size of the BAW resonator group perpendicular to the stacking direction, which helps to form a miniaturized BAW resonator group. The lower layer's adjacent BAW resonators are at least one of a V-shape, trapezoid, or parallelogram structure, further reducing the size of the BAW resonator group perpendicular to the stacking direction. Second, the V-shape, trapezoid, and parallelogram structures form an air gap structure, which can reflect sound waves back to the adjacent lower and upper BAW resonators, thereby reducing sound wave loss and improving the quality factor of the BAW resonator group. Third, in this invention, the acoustic reflection structure is not set by slotting on the substrate, simplifying the fabrication process, reducing fabrication costs, and also improving the structural stability of the BAW resonator group.

[0061] Optionally, the lower layer of bulk acoustic wave resonators includes at least two; one end of the two bulk acoustic wave resonators supports each other in a V-shaped structure, and the other end is supported by a support structure, and the upper layer of bulk acoustic wave resonators is set on the V-shaped space through the first support layer.

[0062] For example, Figure 2 The two bulk acoustic resonators 24 and 25 in the middle and lower layers have a V-shaped structure. One end of the two bulk acoustic resonators 24 and 25 supports each other in a V-shaped structure, and the other end is supported by a support structure. The upper bulk acoustic resonator 26 is set on the V-shaped space through the first support layer 30.

[0063] Alternatively, two bulk acoustic resonators are located on the two sides of a trapezoid via a support structure, and the upper bulk acoustic resonator is positioned on the V-shaped space between the two sides of the trapezoid via a first support layer.

[0064] For example, Figure 3 The two bulk acoustic resonators 24 and 25 in the middle and lower layers are trapezoidal. The two bulk acoustic resonators 24 and 25 are located on the two sides of the trapezoid through the support structure, and the upper bulk acoustic resonator 26 is set on the V-shaped space between the two sides of the trapezoid through the first support layer 30.

[0065] Alternatively, two bulk acoustic resonators are located on the parallel sides of a parallelogram via a support structure, and the upper bulk acoustic resonator is positioned on the V-shaped space between the parallel sides of the parallelogram via a first support layer.

[0066] For example, see Figure 4 and Figure 5The lower-layer two-body acoustic resonators 24 and 25 are in the shape of a parallelogram. The two-body acoustic resonators 24 and 25 are located on the parallel sides of the parallelogram through a support structure, and the upper-layer bulk acoustic resonator 26 is disposed on the V-shaped space between the parallel sides of the parallelogram through the first support layer 30.

[0067] Optionally, the lower layer includes at least four bulk acoustic wave resonators, and the V-shaped structure formed by two adjacent bulk acoustic wave resonators in the lower layer includes an inverted V-shaped structure or an upright V-shaped structure; the upper layer bulk acoustic wave resonators are set on the V-shaped space through the first support layer, and the V-shaped space is formed by two adjacent upright V-shaped bulk acoustic wave resonators in the lower layer.

[0068] For example, see Figure 6 The lower layer comprises four bulk acoustic wave resonators: bulk acoustic wave resonator 24, bulk acoustic wave resonator 25, bulk acoustic wave resonator 26, and bulk acoustic wave resonator 27. Adjacent bulk acoustic wave resonators 24 and 25 in the lower layer support each other in an inverted V-shape. Adjacent bulk acoustic wave resonators 26 and 27 support each other in an inverted V-shape. Adjacent bulk acoustic wave resonators 25 and 26 support each other in an upright V-shape. The upper layer bulk acoustic wave resonator 28 is horizontally positioned above the V-shaped space 50 via the first support layer 30.

[0069] Optional, see Figure 6 The angle β formed by the V-shaped sides of the V-shaped structure is greater than or equal to 0° and less than or equal to 90°. Preferably, the angle β formed by the V-shaped sides of the V-shaped structure is greater than 0° and less than 90°.

[0070] The above-described technical solution reduces the size of the bulk acoustic wave (BAW) resonator array perpendicular to the stacking direction of the BAW resonators, which helps to form a miniaturized BAW resonator array. Furthermore, as the angle β formed by the V-shaped sides of the V-shaped structure decreases, the size of the BAW resonator array perpendicular to the stacking direction of the BAW resonators becomes smaller. The V-shaped space 50 constitutes an air gap structure, which can reflect sound waves back to the adjacent lower and upper BAW resonators, thereby reducing sound wave loss and improving the quality factor of the BAW resonator array. Therefore, in this embodiment of the invention, it is not necessary to set the acoustic reflection structure on the substrate by cutting grooves, simplifying the fabrication process, reducing fabrication costs, and also improving the structural stability of the BAW resonator array.

[0071] Optionally, two adjacent bulk acoustic resonators in the lower layer support each other in an inverted V-shaped structure; or, two adjacent bulk acoustic resonators in the lower layer are supported by a second support layer in an inverted V-shaped structure.

[0072] For example, Figure 6 The first electrodes 20a of the two adjacent bulk acoustic wave resonators 24 and 25 in the middle and lower layers support each other in an inverted V-shaped structure. The first electrodes 20a of the two adjacent bulk acoustic wave resonators 26 and 27 in the lower layer support each other in an inverted V-shaped structure.

[0073] For example, Figure 7 The first electrodes 20a of two adjacent bulk acoustic wave resonators 24 and 25 in the middle and lower layers are arranged in an inverted V-shape through the second support layer 31. The first electrodes 20a of two adjacent bulk acoustic wave resonators 26 and 27 in the lower layer are also arranged in an inverted V-shape through the second support layer 31. The second support layer 31 can be a conductive support layer or an insulating support layer.

[0074] Optionally, the electrodes of two adjacent bulk acoustic wave resonators in the lower layer are electrically connected through an intermediate conductive part; or, the electrodes of two adjacent bulk acoustic wave resonators in the lower layer are in direct contact to achieve electrical connection; or, the electrodes of two adjacent bulk acoustic wave resonators in the lower layer are insulated.

[0075] For example, Figure 7 The second electrodes 20c of the two adjacent bulk acoustic resonators 24 and 25 in the middle and lower layers are electrically connected through the intermediate conductive part 20d. Figure 7 The second electrodes 20c of the two adjacent bulk acoustic resonators 25 and 26 in the middle and lower layers are in direct contact to achieve electrical connection. Figure 6 The second electrodes 20c of the two adjacent bulk acoustic resonators 24 and 25 in the middle and lower layers are spaced apart by a predetermined area to achieve insulation.

[0076] Optionally, the bulk acoustic resonator may also include a temperature compensation layer, which comprises a material with a positive frequency drift coefficient.

[0077] For example, see Figure 8 The bulk acoustic wave resonators 24, 25, 26, 27 and 28 also include a temperature compensation layer 20e, which is located on the surface of the second electrode 20c away from the piezoelectric layer 20b.

[0078] Optionally, the temperature compensation layer 20e is located at at least one of the following locations: within the piezoelectric layer 20b, on the surface of the piezoelectric layer 20b adjacent to the first electrode 20a, on the surface of the piezoelectric layer 20b adjacent to the second electrode 20c, within the first electrode 20a, on the surface of the first electrode 20a facing away from the piezoelectric layer 20b, within the second electrode 20c, and on the surface of the second electrode 20c facing away from the piezoelectric layer 20b.

[0079] Specifically, the temperature compensation layer 20e includes a positive frequency drift coefficient material, which can compensate for the changes in the electrical and mechanical properties of the bulk acoustic wave resonator caused by temperature variations, thereby improving the temperature stability of the bulk acoustic wave resonator. For example, the temperature compensation layer 20e can be selected from a positive frequency drift coefficient material such as silicon dioxide.

[0080] This invention also provides a bulk acoustic wave filter, including at least one substrate. The substrate includes a first surface and a second surface disposed opposite to the first surface. The first surface of the substrate is provided with at least one bulk acoustic wave resonator group as described in any of the above technical solutions. The substrate and the lower layer of the bulk acoustic wave resonator group supported by the substrate form a predetermined angle.

[0081] For example, see Figure 9 The bulk acoustic wave filter includes a substrate 001, which includes a first surface 101 and a second surface 102 disposed opposite to the first surface 101. A bulk acoustic wave resonator group 2 is disposed on the first surface 101 of the substrate 001. The substrate 001 and the lower layer of the bulk acoustic wave resonator group 2 supported by the substrate 001 form a preset angle α.

[0082] Optionally, when there are at least two substrates, a bonding structure can be provided for sealing the connection between the different substrates. See, for an example. Figure 10 The bulk acoustic wave (BAW) filter includes two substrates, substrate 001 and substrate 002. A BAW resonator group 2 is disposed on the first surface 101 of substrate 001. A predetermined angle α is formed between substrate 001 and the BAW resonators in the BAW resonator group 2 supported by substrate 001. A BAW resonator group 3 is disposed on the first surface 101 of substrate 002. A predetermined angle α is formed between substrate 002 and the lower layer of the BAW resonator group 3 supported by substrate 002.

[0083] Specifically, the preset included angle α is within the range of greater than 0° and less than 90°. The larger the value of the preset included angle α, the smaller the angle β formed by the V-shaped sides of the V-shaped structure of the two adjacent bulk acoustic wave resonators in the lower layer, and the smaller the size of the bulk acoustic wave filter in the direction perpendicular to the thickness of the substrate 001. For ease of description, the direction perpendicular to the thickness of the substrate 001 is the X direction in the XOY plane rectangular coordinate system, and the direction parallel to the thickness of the substrate 001 is the Y direction in the XOY plane rectangular coordinate system.

[0084] The technical solution provided by this invention has three aspects. First, the bulk acoustic wave (SAW) resonators in the bulk acoustic wave (BAW) resonator group are stacked, which reduces the size of the BAW filter in the direction perpendicular to the substrate thickness, thus facilitating the formation of a miniaturized BAW filter. The substrate and the lower layer of the BAW resonator group supported by the substrate form a predetermined angle between them; that is, two adjacent BAW resonators in the lower layer form an upright V-shaped structure or an inverted V-shaped structure, further reducing the size of the BAW filter in the direction perpendicular to the substrate thickness. Furthermore, as the angle formed by the V-shaped sides of the V-shaped structure decreases, the size of the BAW filter in the direction perpendicular to the substrate thickness becomes smaller. Second, since the V-shaped structure constitutes an air-gap structure BAW resonator, sound waves can be reflected back to the adjacent lower and upper layer BAW resonators, thereby reducing sound wave loss and improving the quality factor of the BAW filter. Third, in this invention embodiment, there is no need to set the sound reflection structure on the substrate by cutting grooves, which simplifies the manufacturing process, reduces manufacturing costs, and also improves the structural stability of the BAW resonator group.

[0085] Optionally, the substrate includes an adjacent first substrate and a second substrate; at least one bulk acoustic wave resonator group is disposed on the first surface of the first substrate, and at least one bulk acoustic wave resonator group is disposed on the second surface of the second substrate, and the bulk acoustic wave resonator groups between the first substrate and the second substrate are distributed in an interdigital pattern.

[0086] For example, see Figure 11 When the first substrate is substrate 001, a bulk acoustic wave resonator group 2 is provided on the first surface 101 of substrate 001. When the second substrate is substrate 002, a bulk acoustic wave resonator group 3 is provided on the second surface 102 of substrate 002. The bulk acoustic wave resonator group 2 and the bulk acoustic wave resonator group 3 between substrate 001 and substrate 002 are distributed in an interdigitated manner.

[0087] Specifically, the bulk acoustic wave resonators are arranged in an interdigitated pattern between two adjacent substrates, which reduces the size of the bulk acoustic wave filter parallel to the substrate thickness direction, thus helping to form a miniaturized bulk acoustic wave filter.

[0088] Optionally, it also includes a conductive interconnect structure; the conductive interconnect structure is used to lead the electrical signal of the bulk acoustic wave resonator group to the first surface side of the uppermost substrate, and / or, the conductive interconnect structure is used to lead the electrical signal of the bulk acoustic wave resonator group to the second surface side located on the lowermost substrate.

[0089] For example, see Figures 9-11 It also includes a conductive interconnect structure 60, a conductive via 61, a conductive bonding layer 62, and a redistribution layer 63. See also Figure 10The conductive interconnect structure 60 is used to lead out the electrical signals of the bulk acoustic wave resonator group 2 and the bulk acoustic wave resonator group 3 to the second surface 102 side located on the bottommost substrate 001. At the same time, the conductive interconnect structure 60 is also used to lead out the electrical signals of the bulk acoustic wave resonator group 2 and the bulk acoustic wave resonator group 3 to the first surface 101 side located on the topmost substrate 002.

[0090] Specifically, the conductive interconnect structure 60 is used to lead out the electrical signal of the bulk acoustic wave resonator group, so as to facilitate the electrical connection between the electrical signal of the bulk acoustic wave filter and the compensation circuit composed of at least one of capacitors, inductors, resistors and functional chips.

[0091] Optionally, it also includes a wafer cover plate located on the first surface side of the uppermost substrate; the conductive interconnect structure is used to guide the electrical signals of the bulk acoustic resonator group to the surface of the wafer cover plate away from the uppermost substrate.

[0092] Optionally, a bonding structure for connection can be provided between the wafer cover and the substrate. See, for example... Figure 10 The bulk acoustic wave filter also includes a wafer cover plate 70, which is located on the first surface 101 side of the uppermost substrate 002. In addition to the conductive interconnect structure 60 used to lead the electrical signals of the bulk acoustic wave resonator group to the second surface 102 side of the lowermost substrate 001, the conductive interconnect structure 60 can also be used to lead the electrical signals of the bulk acoustic wave resonator group to the surface of the wafer cover plate 70 opposite to the uppermost substrate 002. Figure 9 In this diagram, only one substrate is shown, with both the topmost and bottommost substrates being substrate 001. For example, the substrates and the wafer cover 70 can be made of the same or different materials.

[0093] Optional, see Figure 10 The wafer cover plate 70 has a groove 70a on its surface adjacent to the uppermost substrate. For example, Figure 10 There are two substrates: the top substrate is substrate 002, and the bottom substrate is substrate 001. The groove 70a can reflect the sound waves back to the bulk acoustic resonator group on one side of the top substrate to improve the quality factor of the bulk acoustic filter.

[0094] Optionally, the first or second electrode of the bulk acoustic resonator adjacent to the conductive interconnect structure is connected to the conductive interconnect structure via a conductive connection portion.

[0095] For example, see Figure 9 The second electrode 20c of the bulk acoustic wave resonator 24 adjacent to the conductive interconnect structure 60 is connected to the conductive interconnect structure 60 via the conductive connection portion 80. The second electrode 20c of the bulk acoustic wave resonator 27 adjacent to the conductive interconnect structure 60 is connected to the conductive interconnect structure 60 via the conductive connection portion 81.

[0096] See Figure 11 The second electrode 20c of the bulk acoustic wave resonator 24a adjacent to the conductive interconnect structure 60 is connected to the conductive interconnect structure 60 via a conductive connection portion 82. The second electrode 20c of the bulk acoustic wave resonator 27b adjacent to the conductive interconnect structure 60 is connected to the conductive interconnect structure 60 via a conductive connection portion 83.

[0097] The second electrode 20c of the bulk acoustic wave resonator 24c adjacent to the conductive interconnect structure 60 is connected to the conductive interconnect structure 60 via a conductive connection portion 84. The second electrode 20c of the bulk acoustic wave resonator 27c adjacent to the conductive interconnect structure 60 is connected to the conductive interconnect structure 60 via a conductive connection portion 85. In the bulk acoustic wave resonator group 2, the second electrode 20c of the bulk acoustic wave resonator 27a and the second electrode 20c of the bulk acoustic wave resonator 24b are connected to the conductive interconnect structure 60 via a conductive connection portion 86.

[0098] In summary, the first or second electrode of the bulk acoustic wave resonator adjacent to the conductive interconnect structure is connected to the conductive interconnect structure via a conductive connection. Combined with the connection method of the conductive interconnect structure and the bulk acoustic wave resonator group, the electrical signal of the bulk acoustic wave resonator group is extracted, facilitating the electrical connection of the bulk acoustic wave filter with a compensation circuit composed of at least one of capacitors, inductors, resistors, and functional chips. It should be noted that within a bulk acoustic wave resonator group, electrical connections between different bulk acoustic wave resonators can be achieved through conductive connections of a preset shape or direct contact. The shape and size of the conductive connection can be set according to actual conditions.

[0099] Within a bulk acoustic wave resonator array, the electrodes of two adjacent bulk acoustic wave resonators are electrically connected either through direct contact or through an intermediate conductive portion. For example, see [link to example]. Figure 9 and Figure 12 The lower-layer bulk acoustic resonators 24, 25, 26 and 27 are connected in series and in parallel with the upper-layer bulk acoustic resonator 28.

[0100] Optionally, a first bulk acoustic wave resonator group is disposed on the first surface of the first substrate, the first bulk acoustic wave resonator group including at least two upper bulk acoustic wave resonators; the bulk acoustic wave filter further includes a second substrate located on the upper layer of the first substrate, the second surface of the second substrate being disposed on the second bulk acoustic wave resonator group; the upper layer of the second bulk acoustic wave resonator group is located between the upper layer bulk acoustic wave filters of the first bulk acoustic wave resonator group.

[0101] For example, see Figure 11The first substrate 001 has a first bulk acoustic wave resonator group 2 disposed on its first surface 101. The first bulk acoustic wave resonator group 2 includes two upper bulk acoustic wave resonators 28a and 28b. The bulk acoustic wave filter also includes a second substrate 002 located on the upper layer of the first substrate 001, and a second bulk acoustic wave resonator group 3 disposed on its second surface 102. The upper layer of the second bulk acoustic wave resonator group 3, a bulk acoustic wave resonator 28c, is located between the upper layer bulk acoustic wave resonators 28a and 28b of the first bulk acoustic wave resonator group 2. The first bulk acoustic wave resonator group 2 also includes lower layer bulk acoustic wave resonators 24a, 25a, 26a, 27a, 24b, 25b, 26b, and 27b. The second bulk acoustic resonator group 3 also includes bulk acoustic resonators 24c, 25c, 26c, and 27c located in the lower layer.

[0102] The technical solution provided by this invention, in a first aspect, involves stacking bulk acoustic wave (BAW) resonators in a bulk acoustic wave (BAW) resonator group, which reduces the size of the BAW filter perpendicular to the substrate thickness, thus facilitating the formation of a miniaturized BAW filter. The substrate and the lower layer of the BAW resonator group supported by the substrate form a predetermined angle between them; that is, adjacent BAW resonators in the lower layer form an upright V-shaped structure or an inverted V-shaped structure, further reducing the size of the BAW filter perpendicular to the substrate thickness. Furthermore, as the angle formed by the V-shaped sides of the V-shaped structure decreases, the size of the BAW filter perpendicular to the substrate thickness becomes smaller. When the number of substrates is greater than or equal to two, the BAW resonators between adjacent substrates are distributed in an interdigitated pattern, reducing the size of the BAW filter parallel to the substrate thickness, thereby facilitating the formation of a miniaturized BAW filter. In a second aspect, the V-shaped structure constitutes an air-gap structure BAW resonator, which can reflect sound waves back to adjacent lower and upper layer BAW resonators, thereby reducing sound wave loss and improving the quality factor of the BAW filter. Thirdly, in the embodiments of the present invention, it is not necessary to set the acoustic reflection structure on the substrate by means of groove, which simplifies the manufacturing process, reduces the manufacturing cost, and also improves the structural stability of the bulk acoustic resonator group.

[0103] Optionally, in the thickness direction parallel to the substrate, the spacing between adjacent substrates is less than the sum of the heights of the bulk acoustic wave resonator groups that are interdigitated between adjacent substrates.

[0104] For example, see Figure 11In the thickness direction parallel to substrate 001, the height S1 of bulk acoustic wave resonator group 2 is less than the distance S3 between substrate 001 and substrate 002, and the height S2 of bulk acoustic wave resonator group 3 is less than the distance S3 between substrate 001 and substrate 002. The distance S3 between adjacent substrates 001 and 002 is less than the sum of the heights S1 and S2 of the bulk acoustic wave resonator group 2 and bulk acoustic wave resonator group 3, which are interdigitated between adjacent substrates 001 and substrate 001.

[0105] For example, see Figure 9 In the thickness direction parallel to the substrate 001, the height S1 of the bulk acoustic resonator group 2 is less than the distance S4 between the substrate 001 and the wafer cover plate 70.

[0106] Optionally, in the horizontal direction, the two groups of acoustic resonators are spaced apart by a preset distance.

[0107] For example, see Figure 11 In the horizontal direction, the two bulk acoustic wave resonator groups 2 and 3, which are distributed in an interdigital pattern, are spaced apart by a predetermined distance. Specifically, in the horizontal direction, the acoustic wave resonators of bulk acoustic wave resonator group 2 and the bulk acoustic wave resonator group 3 are spaced apart by a predetermined distance and are not in contact. The above technical solution increases the isolation between the two bulk acoustic wave resonator groups 2 and 3, which are distributed in an interdigital pattern, and avoids signal crosstalk.

[0108] For example, targeting Figure 6 The illustrated bulk acoustic resonator array is further described in this embodiment of the invention, which also provides a method for fabricating the bulk acoustic resonator array. (See also...) Figure 13 The preparation method includes the following steps:

[0109] Step 110: Provide a substrate and form a first sacrificial layer on the first surface of the substrate.

[0110] See Figure 14 A substrate 001 is provided, and a first sacrificial layer 100 is formed on a first surface 101 of the substrate 001. Exemplarily, the substrate 001 may be made of materials such as single-crystal silicon, gallium arsenide, sapphire, and quartz. Exemplarily, the first sacrificial layer 100 may be made of a material containing silicon oxide, such as phosphosilicate glass (PSG), and may be formed by a deposition process. The thickness of the first sacrificial layer 100 may be controlled by process parameters of the deposition process.

[0111] Step 120: Perform graphical processing on the first sacrificial layer.

[0112] See Figure 14The first sacrificial layer 100 is patterned using photolithography and etching processes.

[0113] Step 130: Form a first electrode on the surface of the first sacrificial layer away from the substrate.

[0114] See Figure 14 The first electrode 20a can be formed on the surface of the first sacrificial layer 100 away from the substrate 001 by sputtering or vapor deposition. For example, the first electrode 20a can be selected from at least one of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper and titanium, which have good conductivity.

[0115] Step 140: Form a piezoelectric layer on the surface of the first electrode.

[0116] See Figure 14 A piezoelectric layer 20b can be formed on the surface of the first electrode 20a through a deposition process. For example, the piezoelectric layer 20b can be selected from at least one of single-crystal piezoelectric thin film materials such as aluminum nitride, zinc oxide, lead zirconate titanate piezoelectric ceramics, lithium niobate, lithium tantalate, and potassium niobate, as well as polycrystalline piezoelectric thin film materials. A certain proportion of rare earth elements can also be doped into the piezoelectric layer 20b to improve the performance of the piezoelectric material layer. It should be noted that aluminum nitride piezoelectric layers, due to their lower inherent losses, lower temperature coefficient, and better thermal conductivity, exhibit superior performance as bulk acoustic wave resonators in piezoelectric layers.

[0117] Step 150: Form a second electrode on the surface of the piezoelectric layer.

[0118] See Figure 14 A second electrode 20c can be formed on the surface of the piezoelectric layer 20b by sputtering or vapor deposition. For example, the second electrode 20c can be selected from at least one of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, and titanium, which have good conductivity. The above steps can form the lower-layer bulk acoustic wave resonators 24, 25, 26, and 27. Adjacent bulk acoustic wave resonators 24 and 25 support each other in an inverted V-shaped structure. Adjacent bulk acoustic wave resonators 26 and 27 support each other in an inverted V-shaped structure. Adjacent bulk acoustic wave resonators 25 and 26 support each other in an upright V-shaped structure.

[0119] Step 160: Form the second sacrificial layer.

[0120] See Figure 14 The second sacrificial layer 200 can be formed through a deposition process.

[0121] Step 170: Planarize the second sacrificial layer.

[0122] See Figure 14The second sacrificial layer 200 can be planarized using a chemical mechanical polishing (CMP) process.

[0123] Step 180: Form the first support layer, the first electrode, the piezoelectric layer and the second electrode sequentially on the V-shaped space.

[0124] See Figure 14 A first support layer 30, a first electrode 20a, a piezoelectric layer 20b, and a second electrode 20c are sequentially formed on the V-shaped space 50 to form an upper-layer bulk acoustic resonator 28 supported by the first support layer 30 on the V-shaped space 50.

[0125] Step 190: Release the first and second sacrificial layers.

[0126] See Figure 14 and Figure 6 Release the first sacrificial layer 100 and the second sacrificial layer 200.

[0127] For example, both the first sacrificial layer 100 and the second sacrificial layer 200 can be made of silicon oxide, and the etching solution can be hydrofluoric acid solution, which can quickly release the first sacrificial layer 100.

[0128] This invention also provides a communication device, including any of the bulk acoustic wave filters described in the above technical solutions; the communication device includes at least one of a filter, a duplexer, and a multiplexer.

[0129] Specifically, a duplexer can be simply understood as the operation of two bulk acoustic wave filters: one is a receiving bulk acoustic wave filter to receive signals, and the other is a transmitting bulk acoustic wave filter to transmit signals. A multiplexer can be simply understood as a communication device composed of at least two duplexers.

[0130] The communication device provided in this embodiment of the invention includes any of the bulk acoustic wave filters described in the above technical solutions, and therefore has the beneficial effects of the bulk acoustic wave filters described above, which will not be repeated here.

[0131] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A bulk acoustic resonator array, characterized in that, include: At least three bulk acoustic wave resonators, each of the bulk acoustic wave resonators comprising a stacked structure of a first electrode, a piezoelectric layer, and a second electrode; The at least three bulk acoustic wave resonators are stacked, and the upper bulk acoustic wave resonator is disposed on the two adjacent bulk acoustic wave resonators of the lower layer through the first support layer. With the support of the support structure, the two adjacent bulk acoustic wave resonators of the lower layer are at least one of V-shaped, trapezoidal and parallelogram. At least one of the V-shaped, trapezoidal, and parallelogram structures constitutes an air gap structure that can reflect sound waves back to the adjacent lower and upper volume acoustic resonators.

2. The bulk acoustic resonator assembly according to claim 1, characterized in that, The lower-level bulk acoustic resonator includes at least two; One end of each of the two bulk acoustic resonators is supported by a V-shaped structure, and the other end is supported by a support structure. The upper bulk acoustic resonator is disposed on the V-shaped space through the first support layer. Alternatively, the two bulk acoustic wave resonators are located on the two sides of a trapezoid via a support structure, wherein the two bulk acoustic wave resonators include a first bulk acoustic wave resonator and a second bulk acoustic wave resonator; the support structure includes a first side and a second side, one end of the first side and the second side supporting each other to form a V-shape; one end of the first bulk acoustic wave resonator and the other end of the first side supporting each other to form a V-shape, and one end of the second bulk acoustic wave resonator and the other end of the second side supporting each other to form a V-shape; the upper bulk acoustic wave resonator is disposed on the V-shaped space between the two sides of the trapezoid via the first support layer. Alternatively, the two bulk acoustic wave resonators are located on the parallel sides of a parallelogram via a support structure, and the upper bulk acoustic wave resonator is disposed on the V-shaped space between the parallel sides of the parallelogram via the first support layer; the two bulk acoustic wave resonators include a third bulk acoustic wave resonator and a fourth bulk acoustic wave resonator arranged in parallel; the support structure includes a third side and a fourth side arranged in parallel and spaced apart; one end of the third bulk acoustic wave resonator and one end of the third side support each other to form a V-shaped structure, one end of the fourth bulk acoustic wave resonator and one end of the fourth side support each other to form a V-shaped structure, and the other end of the third side and the other end of the fourth bulk acoustic wave resonator support each other to form a V-shaped structure; or, one end of the third bulk acoustic wave resonator and one end of the third side support each other to form a V-shaped structure, one end of the fourth bulk acoustic wave resonator and one end of the fourth side support each other to form a V-shaped structure, and the other end of the fourth side and the other end of the third bulk acoustic wave resonator support each other to form a V-shaped structure.

3. The bulk acoustic resonator assembly according to claim 1, characterized in that, When the two adjacent bulk acoustic resonators in the lower layer form a V-shaped structure, the lower layer includes at least four bulk acoustic resonators. The V-shaped structure formed by the two adjacent bulk acoustic resonators in the lower layer includes an inverted V-shaped structure or an upright V-shaped structure. The upper-layer bulk acoustic resonator is disposed on the V-shaped space through the first support layer. The V-shaped space is composed of two adjacent upright V-shaped bulk acoustic resonators disposed on the lower layer.

4. The bulk acoustic resonator assembly according to claim 3, characterized in that, The angle formed by the V-shaped sides of the V-shaped structure is greater than or equal to 0° and less than or equal to 90°.

5. The bulk acoustic resonator assembly according to claim 1, characterized in that, The first electrodes of the two adjacent bulk acoustic resonators in the lower layer support each other in an inverted V-shaped structure. Alternatively, one end of the first electrode of the two adjacent bulk acoustic resonators in the lower layer is in an inverted V-shaped structure under the support of the second support layer, and the two apex corners of the second support layer located on the same surface are respectively used to support one end of the first electrode of the two adjacent bulk acoustic resonators in the lower layer.

6. The bulk acoustic resonator assembly according to claim 1, characterized in that, The electrodes of two adjacent bulk acoustic resonators in the lower layer are electrically connected through a middle conductive part; Alternatively, the electrodes of two adjacent bulk acoustic resonators in the lower layer can be in direct contact to achieve electrical connection; Alternatively, the electrodes of the two adjacent bulk acoustic resonators in the lower layer are insulated.

7. The bulk acoustic resonator assembly according to claim 1, characterized in that, The bulk acoustic resonator also includes a temperature compensation layer, which comprises a material with a positive frequency drift coefficient.

8. The bulk acoustic resonator assembly according to claim 7, characterized in that, The temperature compensation layer is located at at least one of the following locations: within the piezoelectric layer, on the surface of the piezoelectric layer adjacent to the first electrode, on the surface of the piezoelectric layer adjacent to the second electrode, within the first electrode, on the surface of the first electrode facing away from the piezoelectric layer, within the second electrode, and on the surface of the second electrode facing away from the piezoelectric layer.

9. A bulk acoustic wave filter, comprising at least one substrate, the substrate including a first surface and a second surface disposed opposite to the first surface, characterized in that, The first surface of the substrate is provided with at least one bulk acoustic resonator group as described in any one of claims 1-8; The substrate and the lower layer of the bulk acoustic wave resonator group supported by the substrate form a predetermined angle.

10. The bulk acoustic wave filter according to claim 9, characterized in that, The substrate includes an adjacent first substrate and a second substrate; The first substrate has at least one bulk acoustic wave resonator group disposed on its first surface, and the second substrate has at least one bulk acoustic wave resonator group disposed on its second surface. The bulk acoustic wave resonator groups between the first substrate and the second substrate are distributed in an interdigitated pattern.

11. The bulk acoustic wave filter according to claim 9 or 10, characterized in that, It also includes conductive interconnect structures; The conductive interconnect structure is used to lead the electrical signal of the bulk acoustic wave resonator group to the first surface side of the uppermost substrate, and / or, the conductive interconnect structure is used to lead the electrical signal of the bulk acoustic wave resonator group to the second surface side located on the lowermost substrate.

12. The bulk acoustic wave filter according to claim 11, characterized in that, It also includes a wafer cover plate, which is located on the first surface side of the uppermost substrate; The conductive interconnect structure is used to direct the electrical signals of the bulk acoustic resonator group to the surface of the wafer cover away from the uppermost substrate.

13. The bulk acoustic wave filter according to claim 11, characterized in that, The first or second electrode of the bulk acoustic resonator adjacent to the conductive interconnect structure is connected to the conductive interconnect structure via a conductive connection portion.

14. The bulk acoustic wave filter according to claim 10, characterized in that, A first bulk acoustic wave resonator group is disposed on the first surface of the first substrate, and the first bulk acoustic wave resonator group includes at least two upper-layer bulk acoustic wave resonators. The bulk acoustic wave filter further includes a second substrate located on the upper layer of the first substrate, and a second bulk acoustic wave resonator group is disposed on the second surface of the second substrate. The upper layer of the second bulk acoustic wave resonator group is located between the upper layer bulk acoustic wave resonators of the first bulk acoustic wave resonator group.

15. The bulk acoustic wave filter according to claim 10, characterized in that, In the thickness direction parallel to the substrate, the spacing between adjacent substrates is less than the sum of the heights of the bulk acoustic wave resonator groups that are interdigitated between adjacent substrates.

16. The bulk acoustic wave filter according to claim 10, characterized in that, In the horizontal direction, the two acoustic resonator groups, which are distributed in an interdigital pattern, are spaced apart by a predetermined distance.

17. A communication device, characterized in that, Includes the bulk acoustic wave filter according to any one of claims 9-16; The communication device includes at least one of a filter, a duplexer, and a multiplexer.

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