Highly integrated bulk acoustic wave resonator, filter and method of fabrication

Abstract

The application discloses a highly integrated bulk acoustic resonator, filter and preparation method, and belongs to the technical field of filters.The bulk acoustic resonator comprises an active region and a non-active region surrounding the active region at least partially, and further comprises a substrate, a bottom electrode, a piezoelectric layer and a top electrode arranged in a longitudinal direction, and further comprises a planar inductor, a dielectric layer and a capacitor electrode, wherein the planar inductor is in the same layer as the top electrode, the dielectric layer is located on the side of the planar inductor and the top electrode away from the piezoelectric layer, and the capacitor electrode is arranged on one side of the dielectric layer and forms a capacitor structure with the top electrode, wherein the planar inductor and the capacitor structure are located in the non-active region and are located on the two sides of the active region respectively.The application integrates the inductor and the capacitor in the bulk acoustic resonator, which is conducive to the miniaturization of radio frequency devices.

Description

Technical Field

[0001] This invention relates to the field of filter technology, specifically to a highly integrated bulk acoustic resonator, filter, and fabrication method. Background Technology

[0002] In existing technologies, inductors and capacitors are usually integrated into the input / output / ground terminals of filters or into the RF front-end module. This greatly increases the size of the filter or RF front-end module, which does not meet the current miniaturization requirements of RF devices. At the same time, the integration freedom of capacitors and inductors is limited. Summary of the Invention

[0003] The purpose of this invention is to provide a highly integrated bulk acoustic resonator, filter, and fabrication method to solve the problem that integrating inductors and capacitors into the input or output of filters in the prior art would increase the size of the filters.

[0004] One object of the present invention is to provide a highly integrated bulk acoustic wave resonator, comprising an active region and at least a portion of an active region surrounding the active region. The bulk acoustic wave resonator further comprises a substrate, a bottom electrode, a piezoelectric layer, and a top electrode stacked in a longitudinal direction. The bulk acoustic wave resonator further comprises a planar inductor, a dielectric layer, and a capacitor electrode. The planar inductor is on the same layer as the top electrode. The dielectric layer is located on the side of the planar inductor and the top electrode away from the piezoelectric layer. The capacitor electrode is disposed on one side of the dielectric layer and forms a capacitor structure with the top electrode. The planar inductor and the capacitor structure are located in the active region and are respectively located on both sides of the active region.

[0005] Optionally, the bulk acoustic resonator further includes a cover plate stacked on the dielectric layer, wherein the dielectric layer is provided with a groove on the side away from the top electrode and / or the cover plate is provided with a groove on the side near the piezoelectric layer, and the capacitor electrode is disposed in the groove.

[0006] Optionally, the capacitor electrode includes conductive adhesive, the groove is disposed on the side of the dielectric layer away from the top electrode, the conductive adhesive fills the groove, and the conductive adhesive is simultaneously bonded to the side of the cover plate near the piezoelectric layer and the sidewall of the groove; or, the capacitor electrode includes conductive adhesive, the groove is disposed on the side of the cover plate near the piezoelectric layer, the conductive adhesive fills the groove, and the conductive adhesive is simultaneously bonded to the side of the dielectric layer away from the top electrode and the sidewall of the groove.

[0007] Optionally, the capacitor electrode includes conductive adhesive, and the groove includes a first groove and a second groove. The first groove is disposed on the side of the dielectric layer away from the top electrode, and the second groove is disposed on the side of the cover plate near the piezoelectric layer. The first groove and the second groove are connected, and the conductive adhesive fills the groove.

[0008] Optionally, the first groove and the second groove are staggered.

[0009] Another object of the present invention is to provide a highly integrated bulk acoustic wave resonator, including an active region and at least a portion of an active region surrounding the active region. The bulk acoustic wave resonator further includes a substrate, a bottom electrode, a piezoelectric layer, and a top electrode stacked in a longitudinal direction. The bulk acoustic wave resonator also includes a first capacitor and a second capacitor, one electrode of the first capacitor and one electrode of the second capacitor being in the same layer as the top electrode. The bulk acoustic wave resonator further includes a dielectric layer covering the top electrode. The other electrode of the first capacitor and the other electrode of the second capacitor are located on the side of the dielectric layer away from the top electrode. The first capacitor and the second capacitor are located in the active region and are respectively located on both sides of the active region.

[0010] Another object of the present invention is to provide a bulk acoustic wave filter, including the bulk acoustic wave resonator described above.

[0011] Another object of the present invention is to provide a method for fabricating a bulk acoustic resonator, comprising:

[0012] Provide a first substrate;

[0013] A bottom electrode film, a piezoelectric layer, and a top electrode film are sequentially formed on the first substrate, and the top electrode film is patterned to form a top electrode and a planar inductor.

[0014] A dielectric layer is formed on the top electrode and the planar inductor, and the dielectric layer is patterned to form a groove on the side of the dielectric layer away from the top electrode. A capacitor electrode is filled in the groove so that the capacitor electrode and the top electrode form a capacitor structure. The bulk acoustic resonator includes an active region and an active region at least partially surrounding the active region. The planar inductor and the capacitor structure are located in the active region and are respectively located on both sides of the active region.

[0015] Optionally, the preparation method further includes:

[0016] A second substrate is covered on the capacitor electrode and the dielectric layer;

[0017] The first substrate is peeled off, and the bottom electrode film is patterned to form the bottom electrode;

[0018] A first through-hole is formed in the piezoelectric layer, and a conductive material is filled in the first through-hole to conduct a portion of the bottom electrode and the top electrode film, wherein the bottom electrode and the top electrode are not electrically connected;

[0019] A third substrate is bonded to the side of the piezoelectric layer away from the top electrode;

[0020] A plurality of second vias are formed on the second substrate and / or the dielectric layer, and the plurality of second vias are filled with conductive material;

[0021] A pad is formed on the side of the second substrate away from the third substrate, which is connected to the plurality of second vias one by one. The plurality of second vias respectively connect the planar inductor, the first via, the top electrode, the capacitor electrode and the corresponding pad.

[0022] Optionally, the step of forming a groove on the side of the dielectric layer away from the top electrode includes:

[0023] A groove is formed on the side of the dielectric layer away from the top electrode, or

[0024] A groove is formed on the side of the second substrate near the piezoelectric layer, or

[0025] A first groove is formed on the side of the dielectric layer away from the top electrode, and a second groove is formed on the side of the second substrate near the piezoelectric layer, the first groove and the second groove forming the groove.

[0026] Compared with related technologies, this invention integrates capacitors and inductors simultaneously into the resonator, which is different from the traditional method of integrating capacitors and inductors into the input / output terminals of filters or into the RF front-end module. By integrating the resonator as the basic unit, the device size can be significantly reduced, which is beneficial for miniaturizing RF devices. At the same time, by using a part of the top electrode as one of the plates of the capacitor structure, the top electrode can be reused as a component of the capacitor structure and can be implemented in the same process, which not only reduces the device size but also simplifies the manufacturing process. In addition, since the capacitor and inductor are located on both sides of the active layer, that is, using the non-active area outside the active region as the arrangement position of the capacitor and inductor, the space around the resonator is rationally utilized. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0028] Figure 1This is a first schematic diagram of a bulk acoustic resonator provided in an embodiment of the present invention;

[0029] Figure 2 This is a second schematic diagram of the bulk acoustic resonator provided in an embodiment of the present invention;

[0030] Figure 3 This is a third schematic diagram of the bulk acoustic resonator provided in the embodiments of the present invention;

[0031] Figure 4 This is a fourth schematic diagram of the bulk acoustic resonator provided in the embodiments of the present invention;

[0032] Figure 5 This is a fifth schematic diagram of the bulk acoustic resonator provided in the embodiments of the present invention;

[0033] Figure 6 This is a topology circuit diagram of the bulk acoustic wave filter provided in an embodiment of the present invention;

[0034] Figure 7a This is the first step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention;

[0035] Figure 7b This is the second fabrication process for the bulk acoustic wave filter provided in this embodiment of the invention;

[0036] Figure 7c This is the third step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention;

[0037] Figure 7d This is the fourth step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention;

[0038] Figure 7e This is step five of the fabrication process for the bulk acoustic wave filter provided in this embodiment of the invention;

[0039] Figure 7f This is the sixth step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention;

[0040] Figure 7g This is step seven of the fabrication process for the bulk acoustic wave filter provided in this embodiment of the invention;

[0041] Figure 7h This is the eighth step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention.

[0042] Reference numerals: 10-Substrate; 20-Piezoelectric layer; 21-First via; 30-Capacitor structure; 31-Top electrode; 32-Capacitor electrode; 321-Second groove; 322-First groove; 33-Bottom electrode; 34-Planar inductor; 35-Transition electrode; 36-First capacitor; 37-Second capacitor; 40-Cavity; 50-Opening; 60-Cover plate; 61-Second via; 70-Pad; 80-Dielectric layer; 100-First substrate; 200-Second substrate; 300-Third substrate; A1-Active region; A2-Non-active region. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figure 1 As shown, the present invention provides a highly integrated bulk acoustic wave resonator, comprising a substrate 10, a bottom electrode 33, a piezoelectric layer 20 and a top electrode 31 stacked along the longitudinal direction.

[0045] The substrate 10 can be made of materials such as silicon, silicon carbide, sapphire, and silicon nitride.

[0046] The bottom electrode 33 and the top electrode 31 can be made of one or more metals with good conductivity, such as Mo, Au, Ag, Cu, Al, Ti and W. The materials of the top electrode 31 and the bottom electrode 33 can be the same or different, and the present invention does not make specific limitations in this regard.

[0047] The piezoelectric layer 20 can be made of materials such as AlN (aluminum nitride), AlScN (scandium-doped aluminum nitride), LiTaO3 (lithium tantalate), or LiNbO3 (lithium niobate).

[0048] The bulk acoustic resonator also includes an acoustic mirror, which may include a cavity or a Bragg reflector layer. In this invention, the acoustic mirror includes a cavity 40. Specifically, a groove may be provided on one side of the substrate 10 to form the cavity 40.

[0049] The bulk acoustic resonator also includes an active region A1 and an active region A2 that at least partially surrounds the active region A1. The active region A1 is formed by the overlap of the acoustic mirror, bottom electrode 33, piezoelectric layer 20 and top electrode 31 in the longitudinal direction, and the remaining region is the active region A2. The longitudinal direction here is the thickness direction of the bulk acoustic resonator.

[0050] The bulk acoustic wave resonator also includes a planar inductor 34, a dielectric layer 80, and a capacitor electrode 32. The planar inductor 34 is in the same layer as the top electrode 31, that is, the planar inductor 34 and the top electrode 31 can be made of the same metal. For example, when the top electrode 31 is one or more metals selected from Mo, Au, Ag, Cu, Al, Ti, and W, the planar inductor 34 can be made of the same metal as the top electrode 31, so that the planar inductor 34 and the top electrode 31 can be fabricated using the same process. The dielectric layer 80 is located on the side of the planar inductor 34 and the top electrode 31 away from the piezoelectric layer 20, that is, the dielectric layer 80 covers the planar inductor 34 and the top electrode 31. The dielectric layer 80 can be made of silicon dioxide.

[0051] The capacitor electrode 32 is disposed on one side of the dielectric layer 80 and forms a capacitor structure 30 with the top electrode 31. The planar inductor 34 and the capacitor structure 30 are located in the non-active region A2 and on both sides of the active region A1, respectively. The dielectric layer 80 is provided with an opening 50, which exposes at least a portion of the top electrode 31. At the same time, the dielectric layer 80 can serve as a film layer that physically isolates the capacitor electrode 32 and the top electrode 31, so that the capacitor electrode 32 and the top electrode 31 form the capacitor structure 30.

[0052] In this invention, by integrating capacitors and inductors simultaneously into the resonator, compared to the traditional method of integrating capacitors and inductors into the input / output terminals of a filter or integrating them into the RF front-end module, the resonator is integrated as the basic unit, which can significantly reduce the device size and facilitate the miniaturization of RF devices. At the same time, by using a part of the top electrode 31 as one of the plates of the capacitor structure 30, the top electrode 31 can be reused as a component of the capacitor structure 30, and it can be implemented through the same process, which not only reduces the device size but also simplifies the process. Furthermore, since the capacitor and inductor are located on opposite sides of the active layer, that is, by using the non-active region A2 surrounding the active region A1 as the arrangement position of the capacitor and inductor, the space surrounding the resonator is rationally utilized.

[0053] Here, the top electrode 31 can be a counter electrode formed with the bottom electrode 33, or it can not form a counter electrode with the bottom electrode 33. When it does not form a counter electrode with the bottom electrode 33, the top electrode 31 needs to be separated from the counter electrode of the bottom electrode 33, that is, it does not form an electrical connection relationship. In other words, the capacitor structure can be electrically connected to the top electrode 31 or not.

[0054] In this invention, the bulk acoustic wave resonator also includes a cover plate 60 stacked on the dielectric layer 80. The cover plate 60 can be made of silicon, silicon carbide, spinel, or sapphire. The cover plate 60, the dielectric layer 80, the piezoelectric layer 20, and the top electrode 31 together form a cavity (opening 50) located above the piezoelectric layer 20. The side of the dielectric layer 80 away from the top electrode 31 and / or the side of the cover plate 60 near the piezoelectric layer 20 are provided with grooves. The capacitor electrode 32 is disposed in the grooves. Compared with the capacitor electrode 32 being disposed on the upper surface of the dielectric layer 80, the capacitor electrode 32 is embedded in the grooves, that is, the capacitor electrode 32 does not protrude from the grooves. In this way, compared with the conventional bulk acoustic wave resonator, although the capacitor electrode 32 is added, the thickness of the bulk acoustic wave resonator is not increased. This ensures that the bulk acoustic wave resonator maintains a small thickness, which is beneficial to the miniaturization of the bulk acoustic wave resonator.

[0055] Furthermore, the capacitance of the capacitor structure 30 can be adjusted. For example, by changing the depth of the groove to make it larger or smaller, the distance between the capacitor electrode 32 and the top electrode 31 can be changed, thereby adjusting the capacitance of the capacitor structure 30. The capacitance of the capacitor structure 30 can also be adjusted by changing the facing area between the capacitor electrode 32 and the top electrode 31.

[0056] In this invention, the capacitor electrode 32 includes conductive adhesive, which is an adhesive that has a certain conductivity after curing or drying. The conductive adhesive can be formed by resin matrix, conductive particles and dispersing additives, auxiliaries, etc. The conductive adhesive can achieve both conductivity and adhesion.

[0057] like Figure 1 As shown, in one embodiment of the present invention, the groove is disposed on the side of the dielectric layer 80 away from the top electrode 31, that is, the groove is disposed on the upper surface of the dielectric layer 80, and the conductive adhesive is filled in the groove. The conductive adhesive is flush with the upper surface of the dielectric layer 80, that is, the conductive adhesive completely fills the groove but does not protrude from the groove. It can be seen that the top surface of the conductive adhesive can contact the cover plate 60, and the rest of the conductive adhesive contacts the inner wall of the groove, so that the cover plate 60 can be bonded to the dielectric layer 80 by the conductive adhesive, thereby making the bonding between the dielectric layer 80 and the cover plate 60 more firm and ensuring the stability of the cavity (i.e., the opening 50) formed by the cover plate 60, the dielectric layer 80, the piezoelectric layer 20 and the top electrode 31.

[0058] like Figure 2As shown, in one embodiment of the present invention, the groove is disposed on the side of the cover plate 60 near the piezoelectric layer 20, that is, the groove is disposed on the lower surface of the cover plate 60, and conductive adhesive is filled in the groove. The conductive adhesive is flush with the lower surface of the cover plate 60, and the conductive adhesive does not protrude from the groove. In this case, the cover plate 60 can also be bonded to the dielectric layer 80 by the conductive adhesive, making the bond between the dielectric layer 80 and the cover plate 60 stronger. Unlike the above embodiment where the groove is disposed on the dielectric layer 80, in this embodiment the groove is disposed on the cover plate 60, which increases the distance between the conductive adhesive in the groove and the top electrode 31, thereby reducing the capacitance value of the capacitor structure 30. This makes the bulk acoustic wave resonator also suitable for scenarios where the capacitance value requirement of the capacitor structure 30 is relatively small.

[0059] like Figure 3 As shown, in another embodiment of the present invention, the groove includes a first groove 322 and a second groove 321. The first groove 322 is disposed on the side of the dielectric layer 80 away from the top electrode 31, and the second groove 321 is disposed on the side of the cover plate 60 near the piezoelectric layer 20. The first groove 322 and the second groove 321 are connected, and conductive adhesive is simultaneously filled in the first groove 322 and the second groove 321. Compared with disposing the groove on the dielectric layer 80, the contact area between the conductive adhesive in the groove and the cover plate 60 can be increased, thereby improving the adhesion.

[0060] like Figure 4 As shown, in one embodiment of the present invention, the first groove 322 and the second groove 321 are offset from each other, that is, the first groove 322 and the second groove 321 located on the dielectric layer 80 are not completely aligned. For example, with Figure 4 As shown, the left edge of the first groove 322 is not aligned with the left edge of the second groove 321. The left edge of the first groove 322 is further away from the opening 50 than the left edge of the second groove 321. At the same time, the right edge of the first groove 322 is not aligned with the right edge of the second groove 321. The right edge of the first groove 322 is closer to the opening 50 than the right edge of the second groove 321. Therefore, compared with the case where the left and right edges of the first groove 322 are aligned with the left and right edges of the second groove 321 respectively, the staggered arrangement of the first groove 322 and the second groove 321 can increase the contact area between the conductive adhesive and the dielectric layer 80 and the cover plate 60 respectively, thereby improving the adhesion. Moreover, the staggered arrangement of the first groove 322 and the second groove 321 can also increase the facing area between the conductive adhesive and the top electrode 31, thereby increasing the capacitance value of the capacitor structure 30, which is suitable for scenarios that require a larger capacitance value.

[0061] In other embodiments of the present invention, the first groove 322 and the second groove 321 are offset from each other. Alternatively, the left edge of the first groove 322 may not be aligned with the left edge of the second groove 321, while the right edge of the first groove 322 may be aligned with the right edge of the second groove 321. Or, the left edge of the first groove 322 may be aligned with the left edge of the second groove 321, but the right edge of the first groove 322 may not be aligned with the right edge of the second groove 321.

[0062] like Figure 5 As shown, in one embodiment of the present invention, the bulk acoustic wave resonator includes an active region A1 and a non-active region A2 at least partially surrounding the active region A1. The bulk acoustic wave resonator also includes a substrate 10, a bottom electrode 33, a piezoelectric layer 20, and a top electrode 31 stacked along the longitudinal direction. The bulk acoustic wave resonator also includes a first capacitor 36 and a second capacitor 37. One electrode of the first capacitor 36 and one electrode of the second capacitor 37 are on the same layer as the top electrode 31. The bulk acoustic wave resonator also includes a dielectric layer 80 covering the top electrode 31. The other electrode of the first capacitor 36 and the other electrode of the second capacitor 37 are located on the side of the dielectric layer 80 away from the top electrode 31. The first capacitor 36 and the second capacitor 37 are located in the non-active region A2 and are respectively located on both sides of the active region A1, i.e., two capacitors are provided in the non-active region A2, without a planar inductor. The electrodes of the first capacitor 36 and the second capacitor 37 on the same layer as the top electrode 31 may or may not be electrically connected to the top electrode 31. Figure 5 In the first capacitor 36, the plate on the same layer as the top electrode 31 is electrically connected to the top electrode 31, while the plate on the same layer as the second capacitor 37 is not electrically connected to the top electrode 31.

[0063] like Figure 1As shown, in this invention, to form the interconnection traces of the bulk acoustic wave resonator, a first via 21 can be provided in the piezoelectric layer 20. This first via 21 penetrates the piezoelectric layer 20. After patterning the top electrode film, the top electrode film forms three independent parts: a top electrode 31, a planar inductor 34, and a transition electrode 35. The top electrode 31, planar inductor 34, and transition electrode 35 are not electrically connected to each other. The transition electrode 35 is connected to the bottom electrode 33 through the first via 21. Simultaneously, a second via 61 is also formed in the cover plate 60 and / or the dielectric layer 80. The first via 21 and the second via... The space 61 is filled with metal material, so that the bottom electrode 33 can be connected to the outside of the cover plate 60 through the first through hole 21, the transition electrode 35 and the second through hole 61. The capacitor electrode 32 and the top electrode 31 can be connected to the outside of the cover plate 60 through the corresponding second through hole 61. The planar inductor 34 can be connected to the outside of the cover plate 60 through the corresponding second through hole 61. Multiple pads 70 are provided on the side of the cover plate 60 away from the piezoelectric layer 20. The multiple pads 70 correspond one-to-one with the second through hole 61, so that signal input or output to the planar inductor 34, the top electrode 31 and the bottom electrode 33 and the capacitor structure 30 can be realized.

[0064] like Figure 6 As shown, the present invention also provides a bulk acoustic wave filter, which includes the above-mentioned bulk acoustic wave resonators. Specifically, the number of bulk acoustic wave resonators can be multiple, and the multiple bulk acoustic wave resonators can be connected in series and in parallel to form a trapezoidal filter.

[0065] The present invention also provides a method for fabricating a bulk acoustic resonator, the method comprising:

[0066] Step S1: Provide a first substrate 100.

[0067] The first substrate 100 can be made of silicon, silicon carbide, spinel or sapphire, etc.

[0068] Step S2: As Figure 7a and Figure 7b A bottom electrode thin film, a piezoelectric layer 20, and a top electrode thin film are sequentially formed on the first substrate 100. The top electrode thin film is patterned to form a top electrode 31 and a planar inductor 34.

[0069] In this process, a bottom electrode thin film is formed on the first substrate 100. The bottom electrode 33 can be formed using PVD (magnetron sputtering) technology. The bottom electrode 33 and the top electrode 31 can be formed using one or more metals with good conductivity, such as Mo, Au, Ag, Cu, Al, Ti and W. The piezoelectric layer 20 can be formed using AlN (aluminum nitride), AlScN (scandium-doped aluminum nitride), LiTaO3 (lithium tantalate) or LiNbO3 (lithium niobate). After the top electrode thin film is formed, the top electrode thin film is patterned to form the top electrode 31 and the planar inductor 34 by photolithography and etching processes.

[0070] Step S3: As Figure 7c A dielectric layer 80 is formed on the top electrode 31 and the planar inductor 34, and the dielectric layer 80 is patterned to form a groove on the side of the dielectric layer 80 away from the top electrode 31. A capacitor electrode 32 is filled in the groove so that the capacitor electrode 32 and the top electrode 31 form a capacitor structure 30. The bulk acoustic resonator includes an active region A1 and an active region A2 that at least partially surrounds the active region A1. The planar inductor 34 and the capacitor structure 30 are located in the active region A2 and are located on both sides of the active region A1, respectively.

[0071] Using silicon dioxide as the dielectric layer 80, the dielectric layer is formed on the top electrode 31 and the planar inductor 34, and the dielectric layer 80 is patterned to form an opening at the position of the active region A1 corresponding to the dielectric layer 80, and a groove at the position of the non-active region A2. Here, the opening and groove can be formed on the dielectric layer 80 by photolithography and etching processes. The groove is filled with a conductive adhesive composed of one or more metals selected from Mo, Au, Ag, Cu, Al, Ti and W to form a capacitor electrode 32. At least a portion of the capacitor electrode 32 overlaps with the edge of the top electrode 31 in the longitudinal direction. Thus, the capacitor electrode 32 and the top electrode 31 can each serve as one of the plates of a parallel plate capacitor to form a capacitor structure 30.

[0072] By integrating the capacitor and inductor into the bulk acoustic wave resonator, the device size can be significantly reduced, which is beneficial for miniaturizing radio frequency devices. At the same time, by using a part of the top electrode 31 as one of the plates of the capacitor structure 30, the top electrode 31 can be reused as a component of the capacitor structure 30 and can be implemented using the same process. This not only reduces the device size but also simplifies the process. Furthermore, since the capacitor and inductor are located on both sides of the active region A1, the non-active region A2 surrounding the active region A1 is used as the arrangement position for the capacitor and inductor, which makes reasonable use of the space surrounding the resonator.

[0073] Step S4: As Figure 7d A second substrate 200 is covered on the capacitor electrode 32 and the dielectric layer 80.

[0074] The second substrate 200 can be made of silicon, silicon carbide, spinel or sapphire, etc.

[0075] Step S5: As Figure 7e and Figure 7f The first substrate 100 is peeled off, and the bottom electrode film is patterned to form the bottom electrode 33.

[0076] After the first substrate 100 is peeled off, the bottom electrode 33 can be patterned. Similarly, the bottom electrode film can be patterned using photolithography and etching processes, just like the top electrode film.

[0077] Step S6: As Figure 7g A first through-hole 21 is formed in the piezoelectric layer 20, and a conductive material is filled in the first through-hole 21 to conduct a portion of the bottom electrode 33 and the top electrode film, wherein the bottom electrode 33 and the top electrode 31 are not electrically connected.

[0078] The top electrode film is patterned into three independent parts: top electrode 31, planar inductor 34, and transition electrode 35. The top electrode 31, planar inductor 34, and transition electrode 35 are not electrically connected to each other. The transition electrode 35 is used to conduct to the bottom electrode 33 through the first through hole 21. The first through hole 21 can be filled with materials such as Cu, Al, and Ag.

[0079] Step S7: As Figure 7h A third substrate 300 is bonded to the side of the piezoelectric layer 20 away from the top electrode 31.

[0080] The third substrate 300 can be made of silicon, silicon carbide, spinel or sapphire, etc.

[0081] Step S8: A plurality of second vias 61 are formed on the second substrate 200 and / or dielectric layer 80, and conductive material is filled in the plurality of second vias 61.

[0082] Multiple second vias 61 are spaced apart on the second substrate 200. The second vias 61 can be filled with materials such as Cu, Al, and Ag. The number of second vias 61 can be determined according to actual needs. For example, since the planar inductor 34 has an input terminal and an output terminal, it requires two corresponding second vias 61. Since the top electrode 31 corresponds to one second via 61, the capacitor structure 30 only needs one second via 61. Specifically, of the two second vias 61 corresponding to the planar inductor 34, one must penetrate the second substrate 200 and be connected to the input terminal of the planar inductor 34, while the other second via 61 must penetrate the second substrate 200 and extend to the bottom of the dielectric layer 80 to be connected to the output terminal of the planar inductor 34. Similarly, the second via 61 corresponding to the top electrode 31 must penetrate the second substrate 200 and extend to the bottom of the dielectric layer 80 to be connected to the top electrode 31. The second via 61 corresponding to the capacitor electrode 32 must penetrate the second substrate 200 and be connected to the capacitor electrode 32.

[0083] Step S9: As Figure 7h A pad 70 is formed on the side of the second substrate 200 away from the third substrate 300, which is connected to a plurality of second vias 61 in a one-to-one manner. The plurality of second vias 61 respectively conduct planar inductor 34, first via 21, top electrode 31, capacitor electrode 32 and corresponding pad 70.

[0084] By forming a pad 70 on the upper surface of the second substrate 200 and making the pad 70 connected to the second via 61, it can serve as an interconnection trace for the planar inductor 34, bottom electrode 33, top electrode 31 and capacitor electrode 32, so as to serve as the input or output terminal of the capacitor structure 30, top electrode 31 and bottom electrode 33 and planar inductor 34 to transmit signals.

[0085] Step S31: The step of forming a groove on the side of the dielectric layer 80 away from the top electrode 31 includes:

[0086] A groove is formed on the side of the dielectric layer 80 away from the top electrode 31, or

[0087] A groove is formed on the side of the second substrate 200 near the piezoelectric layer 20, or

[0088] A first groove 322 is formed on the side of the dielectric layer 80 away from the top electrode 31, and a second groove 321 is formed on the side of the second substrate 200 near the piezoelectric layer 20. The first groove 322 and the second groove 321 form a groove.

[0089] In this invention, the groove can be set in different suitable positions. That is, the groove can be set on the dielectric layer 80 alone, or on the second substrate 200 alone, or on both the second substrate 200 and the dielectric layer 80 at the same time.

[0090] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0091] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly integrated bulk acoustic resonator, characterized in that, The bulk acoustic wave resonator includes an active region and at least a portion of a non-active region surrounding the active region. It further includes a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer, a top electrode, and a transition electrode stacked along a longitudinal direction. The overlapping portion of the acoustic mirror, bottom electrode, piezoelectric layer, and top electrode in the longitudinal direction constitutes the active region. The bulk acoustic wave resonator also includes a planar inductor, a dielectric layer, and a capacitor electrode. The planar inductor, the transition electrode, and the top electrode are on the same layer. The dielectric layer is located on the side of the planar inductor and the top electrode away from the piezoelectric layer. The capacitor electrode is disposed on one side of the dielectric layer and forms a capacitor structure with the top electrode. The planar inductor and the capacitor structure are located in the non-active region and are respectively located on both sides of the active region. The bulk acoustic resonator further includes a cover plate stacked on the dielectric layer, and the dielectric layer is provided with a groove on the side away from the top electrode and / or the cover plate is provided with a groove on the side near the piezoelectric layer, and the capacitor electrode is disposed in the groove; The capacitor electrode includes conductive adhesive, the groove is disposed on the side of the dielectric layer away from the top electrode, the conductive adhesive is filled in the groove, and the conductive adhesive is simultaneously bonded to the side of the cover plate near the piezoelectric layer and the sidewall of the groove; or, the capacitor electrode includes conductive adhesive, the groove is disposed on the side of the cover plate near the piezoelectric layer, the conductive adhesive is filled in the groove, and the conductive adhesive is simultaneously bonded to the side of the dielectric layer away from the top electrode and the sidewall of the groove. The piezoelectric layer has a first through-hole that penetrates the piezoelectric layer. The cover plate and the dielectric layer form a second through-hole. Both the first and second through-holes are filled with metallic material. The bottom electrode is connected to the side of the cover plate away from the piezoelectric layer through the first through-hole, the transition electrode, and the second through-hole. The capacitor electrode and the top electrode are connected to the side of the cover plate away from the piezoelectric layer through the second through-hole. The planar inductor is connected to the side of the cover plate away from the piezoelectric layer through the second through-hole.

2. The highly integrated bulk acoustic resonator according to claim 1, characterized in that, The capacitor electrode includes conductive adhesive, and the groove includes a first groove and a second groove. The first groove is disposed on the side of the dielectric layer away from the top electrode, and the second groove is disposed on the side of the cover plate near the piezoelectric layer. The first groove and the second groove are connected, and the conductive adhesive fills the groove.

3. The highly integrated bulk acoustic resonator according to claim 2, characterized in that, The first groove and the second groove are offset from each other.

4. A bulk acoustic wave filter, characterized in that, The bulk acoustic resonator includes any one of claims 1-3.

5. A method for fabricating a bulk acoustic resonator, characterized in that, include: Provide a first substrate; An acoustic mirror, a bottom electrode film, a piezoelectric layer and a top electrode film are sequentially formed on the first substrate. The top electrode film is patterned to form a top electrode, a transition electrode and a planar inductor. A dielectric layer is formed on the top electrode and the planar inductor, and the dielectric layer is patterned to form a groove on the side of the dielectric layer away from the top electrode. A capacitor electrode is filled in the groove so that the capacitor electrode and the top electrode form a capacitor structure. A cover plate is formed on the side of the dielectric layer away from the first substrate. The bulk acoustic resonator includes an active region and at least a portion of an active region surrounding the active region. The planar inductor and the capacitor structure are located in the active region and are respectively located on both sides of the active region. The overlapping portion of the acoustic mirror, bottom electrode, piezoelectric layer and top electrode in the longitudinal direction constitutes the active region. The capacitor electrode includes conductive adhesive, the groove is disposed on the side of the dielectric layer away from the top electrode, the conductive adhesive is filled in the groove, and the conductive adhesive is simultaneously bonded to the side of the cover plate near the piezoelectric layer and the sidewall of the groove; or, the capacitor electrode includes conductive adhesive, the groove is disposed on the side of the cover plate near the piezoelectric layer, the conductive adhesive is filled in the groove, and the conductive adhesive is simultaneously bonded to the side of the dielectric layer away from the top electrode and the sidewall of the groove. The piezoelectric layer has a first through-hole that penetrates the piezoelectric layer. The cover plate and the dielectric layer form a second through-hole. Both the first and second through-holes are filled with metallic material. The bottom electrode is connected to the side of the cover plate away from the piezoelectric layer through the first through-hole, the transition electrode, and the second through-hole. The capacitor electrode and the top electrode are connected to the side of the cover plate away from the piezoelectric layer through the second through-hole. The planar inductor is connected to the side of the cover plate away from the piezoelectric layer through the second through-hole.

6. The preparation method according to claim 5, characterized in that, The preparation method further includes: A second substrate is covered on the capacitor electrode and the dielectric layer; The first substrate is peeled off, and the bottom electrode film is patterned to form the bottom electrode; A first through-hole is formed in the piezoelectric layer, and a conductive material is filled in the first through-hole to conduct a portion of the bottom electrode and the top electrode film, wherein the bottom electrode and the top electrode are not electrically connected; A third substrate is bonded to the side of the piezoelectric layer away from the top electrode; A plurality of second vias are formed on the second substrate and / or the dielectric layer, and the plurality of second vias are filled with conductive material; A pad is formed on the side of the second substrate away from the third substrate, which is connected to the plurality of second vias one by one. The plurality of second vias respectively connect the planar inductor, the first via, the top electrode, the capacitor electrode and the corresponding pad.

7. The preparation method according to claim 6, characterized in that, The step of forming a groove on the side of the dielectric layer away from the top electrode includes: A groove is formed on the side of the dielectric layer away from the top electrode, or A groove is formed on the side of the second substrate near the piezoelectric layer, or A first groove is formed on the side of the dielectric layer away from the top electrode, and a second groove is formed on the side of the second substrate near the piezoelectric layer, the first groove and the second groove forming the groove.

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