Highly integrated bulk acoustic wave resonator, filter and preparation method

Abstract

The invention discloses a highly-integrated bulk acoustic wave resonator, a filter and a preparation method, and belongs to the technical field of filters, the bulk acoustic wave resonator comprises an active region and a non-active region at least partially surrounding the active region, and the bulk acoustic wave resonator further comprises a substrate, a bottom electrode, a piezoelectric layer and a top electrode which are stacked in the longitudinal direction, the bulk acoustic wave resonator further comprises a planar inductor, a dielectric layer and a capacitor electrode, the planar inductor and the top electrode are in the same layer, the dielectric layer is located on the sides, away from the piezoelectric layer, of the planar inductor and the top electrode, the capacitor electrode is arranged on one side of the dielectric layer, and the capacitor electrode and the top electrode form a capacitor structure. And the planar inductor and the capacitor structure are positioned in the non-active region and are respectively positioned on two sides of the active region. According to the invention, the inductor and the capacitor are integrated in the bulk acoustic wave resonator, so that miniaturization of a radio frequency device is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of filter, in particular to a highly integrated bulk acoustic resonator, filter and preparation method. BACKGROUND

[0002] In the prior art, inductors and capacitors are usually integrated at the input / output / ground of a filter or in a radio frequency front-end module, which greatly increases the size of the filter or the radio frequency front-end module, does not meet the current demand for miniaturization of radio frequency devices, and limits the integration freedom of capacitors and inductors. SUMMARY

[0003] The present application aims to provide a highly integrated bulk acoustic resonator, filter and preparation method to solve the problem of size increase of the filter caused by the integration of inductors and capacitors at the input or output of the filter in the prior art.

[0004] One object of the present application is to provide a highly integrated bulk acoustic resonator, comprising an active region and a non-active region at least partially surrounding the active region, the bulk acoustic resonator further comprising a substrate, a bottom electrode, a piezoelectric layer and a top electrode arranged in a stack along a longitudinal direction, the bulk acoustic resonator further comprising a planar inductor, a dielectric layer and a capacitor electrode, the planar inductor being in the same layer as the top electrode, the dielectric layer being located on a side of the planar inductor and the top electrode away from the piezoelectric layer, the capacitor electrode being disposed on a side of the dielectric layer and forming a capacitor structure with the top electrode, the planar inductor and the capacitor structure being located in the non-active region and on both sides of the active region, respectively.

[0005] Optionally, the bulk acoustic resonator further comprises a cover plate stacked on the dielectric layer, a recess is provided on a side of the dielectric layer away from the top electrode and / or a side of the cover plate close to the piezoelectric layer, and the capacitor electrode is disposed in the recess.

[0006] Optionally, the capacitor electrode comprises conductive glue, the recess is provided on a side of the dielectric layer away from the top electrode, and the conductive glue is filled in the recess and simultaneously bonded to a side of the cover plate close to the piezoelectric layer and a side wall of the recess, or the capacitor electrode comprises conductive glue, the recess is provided on a side of the cover plate close to the piezoelectric layer, and the conductive glue is filled in the recess and simultaneously bonded to a side of the dielectric layer away from the top electrode and a side wall of the recess.

[0007] Optionally, the capacitive electrode comprises conductive glue, the groove comprises a first groove and a second groove, the first groove is arranged on a side of the dielectric layer away from the top electrode, the second groove is arranged on a side of the cover plate close to the piezoelectric layer, the first groove and the second groove are communicated, and the conductive glue is filled in the groove.

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

[0009] It is another object of the present application to provide a highly integrated bulk acoustic wave resonator, comprising an active region and a non-active region at least partially surrounding the active region, the bulk acoustic wave resonator further comprising a substrate, a bottom electrode, a piezoelectric layer and a top electrode arranged in a stack along a longitudinal direction, the bulk acoustic wave resonator further comprising a first capacitor and a second capacitor, one plate of the first capacitor and one plate of the second capacitor being in the same layer as the top electrode, the bulk acoustic wave resonator further comprising a dielectric layer covering the top electrode, the other plate of the first capacitor and the other plate of the second capacitor being located on a side of the dielectric layer away from the top electrode, the first capacitor and the second capacitor being located in the non-active region and on two sides of the active region respectively.

[0010] It is another object of the present application to provide a bulk acoustic wave filter comprising the bulk acoustic wave resonator.

[0011] It is still another object of the present application to provide a method for manufacturing a bulk acoustic wave resonator, comprising: providing a first substrate; forming a bottom electrode film, a piezoelectric layer and a top electrode film on the first substrate in sequence, and patterning the top electrode film to form a top electrode and a planar inductor; forming a dielectric layer on the top electrode and the planar inductor, and patterning the dielectric layer to form a groove on a side of the dielectric layer away from the top electrode, and filling a capacitive electrode in the groove to form a capacitive structure between the capacitive electrode and the top electrode, wherein the bulk acoustic wave resonator comprises an active region and a non-active region at least partially surrounding the active region, the planar inductor and the capacitive structure are located in the non-active region and on two sides of the active region respectively.

[0012] Optionally, the method further comprises: covering a second substrate on the capacitive electrode and the dielectric layer; stripping the first substrate, and patterning the bottom electrode film to form a bottom electrode; forming a first via hole in the piezoelectric layer, and filling a conductive material in the first via hole to conduct the bottom electrode and a part of the top electrode film, wherein the bottom electrode is not electrically connected with the top electrode; bonding a third substrate on a side of the piezoelectric layer away from the top electrode; forming a plurality of second through holes on the second substrate and / or the dielectric layer, and filling the plurality of second through holes with conductive material; forming pads on a side of the second substrate away from the third substrate, the pads being connected to the plurality of second through holes one by one, the plurality of second through holes respectively connecting the planar inductor, the first through hole, the top electrode, the capacitor electrode and the corresponding pads.

[0013] Optionally, the step of forming the groove on the side of the dielectric layer away from the top electrode comprises: forming a groove on the side of the dielectric layer away from the top electrode, or forming a groove on the side of the second substrate close to the piezoelectric layer, or forming a first groove on the side of the dielectric layer away from the top electrode, and forming a second groove on the side of the second substrate close to the piezoelectric layer, the first groove and the second groove forming the groove.

[0014] Compared with the related art, the application integrates the capacitor and the inductor in the resonator, which is based on the resonator unit, so that the device size can be greatly reduced, and the miniaturization of the radio frequency device is facilitated. In addition, a part of the top electrode is used as one of the plates of the capacitor structure, so that the top electrode can be reused as a part of the capacitor structure, and the same process can be used to realize the capacitor structure. Therefore, the device size can be reduced, and the process can be simplified. In addition, the capacitor and the inductor are respectively arranged on the two sides of the active layer, i.e., the non-active area outside the active area is used as the arrangement position of the capacitor and the inductor, so that the peripheral space of the resonator is reasonably utilized. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, illustrate the application, and are used to explain the application, but do not constitute a limitation on the application. In the drawings: Figure 1 is a first schematic diagram of a bulk acoustic wave resonator provided by an embodiment of the application; Figure 2 is a second schematic diagram of a bulk acoustic wave resonator provided by an embodiment of the application; Figure 3 is a third schematic diagram of a bulk acoustic wave resonator provided by an embodiment of the application; Figure 4 is a fourth schematic diagram of a bulk acoustic wave resonator provided by an embodiment of the application; Figure 5 This is a fifth schematic diagram of the bulk acoustic resonator provided in the embodiments of the present invention; Figure 6 This is a topology circuit diagram of the bulk acoustic wave filter provided in an embodiment of the present invention; Figure 7a This is the first step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention; Figure 7b This is the second fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention; Figure 7c This is the third step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention; Figure 7d This is the fourth step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention; Figure 7e This is step five of the fabrication process for the bulk acoustic wave filter provided in this embodiment of the invention; Figure 7f This is the sixth step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention; Figure 7g This is step seven of the fabrication process for the bulk acoustic wave filter provided in this embodiment of the invention; Figure 7h This is the eighth step in the fabrication process of the bulk acoustic wave filter provided in this embodiment of the invention.

[0016] 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

[0017] 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.

[0018] 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.

[0019] The substrate 10 can be made of silicon, silicon carbide, sapphire, silicon nitride, etc.

[0020] The bottom electrode 33 and the top electrode 31 can be made of one or more metals selected from Mo, Au, Ag, Cu, Al, Ti and W, and the materials of the top electrode 31 and the bottom electrode 33 can be the same or different, which is not limited in the present application.

[0021] The piezoelectric layer 20 can be made of AlN (aluminum nitride), AlScN (scandium-doped aluminum nitride), LiTaO3 (lithium tantalate) or LiNbO3 (lithium niobate), etc.

[0022] The bulk acoustic wave resonator further comprises an acoustic mirror, which can include a cavity or a Bragg reflector. In the present application, the acoustic mirror includes a cavity 40, which is formed by providing a groove on one side of the substrate 10.

[0023] The bulk acoustic wave resonator further comprises an active region A1 and a non-active region A2 at least partially surrounding the active region A1, wherein the active region A1 is formed by the overlapping part of the acoustic mirror, the bottom electrode 33, the piezoelectric layer 20 and the top electrode 31 in the longitudinal direction, and the remaining area is the non-active region A2, wherein the longitudinal direction is the thickness direction of the bulk acoustic wave resonator.

[0024] The bulk acoustic wave resonator further comprises 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, i.e. the planar inductor 34 and the top electrode 31 can be made of the same metal, for example, when the top electrode 31 is made of one or more metals selected from Mo, Au, Ag, Cu, Al, Ti and W, the planar inductor 34 can also be made of the same metal as the top electrode 31, so as to facilitate the fabrication of the planar inductor 34 and the top electrode 31 by 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, i.e. the dielectric layer 80 covers the planar inductor 34 and the top electrode 31, wherein the dielectric layer 80 can be made of silicon dioxide.

[0025] The capacitor electrode 32 is provided 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, wherein the dielectric layer 80 is provided with an opening 50, which exposes at least part of the top electrode 31. Meanwhile, the dielectric layer 80 can serve as a film layer for physically isolating the capacitor electrode 32 and the top electrode 31, so as to form the capacitor structure 30.

[0026] In the present application, by integrating the capacitor and the inductor in the resonator simultaneously, compared with the traditional way of integrating the capacitor and the inductor in the input / output of the filter or integrating the capacitor and the inductor on the radio frequency front end module, the device size can be greatly reduced by taking the resonator as the basic unit, which is beneficial to realize the miniaturization of the radio frequency device. Meanwhile, by taking 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 the same process can be used to realize it, which not only reduces the size of the device, but also simplifies the process. In addition, since the capacitor and the inductor are located on both sides of the active layer, i.e. the non-active area A2 outside the active area A1 is used as the arrangement position of the capacitor and the inductor, the peripheral space of the resonator is reasonably utilized.

[0027] Here, the top electrode 31 can be a pair of electrodes formed with the bottom electrode 33, or can not form a pair of electrodes with the bottom electrode 33. When it does not form a pair of electrodes with the bottom electrode 33, the top electrode 31 needs to be spaced apart from the pair of electrodes of the bottom electrode 33, i.e. not in an electrically connected relationship. That is, the capacitor structure can be electrically connected with the top electrode 31 or not.

[0028] In the present application, the bulk acoustic wave resonator further comprises a cover plate 60 stacked on the dielectric layer 80. The cover plate 60 can be made of silicon, silicon carbide, spinel or sapphire, etc. The cover plate 60, the dielectric layer 80, the piezoelectric layer 20 and the top electrode 31 together enclose a cavity (opening 50) 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 close to the piezoelectric layer 20 is provided with a recess, and the capacitor electrode 32 is arranged in the recess. Compared with arranging the capacitor electrode 32 on the upper surface of the dielectric layer 80, the capacitor electrode 32 is embedded in the recess, i.e. the capacitor electrode 32 does not protrude from the recess. Compared with the traditional bulk acoustic wave resonator, although the capacitor electrode 32 is added, the thickness of the bulk acoustic wave resonator is not increased, so that the bulk acoustic wave resonator can maintain a small thickness, which is beneficial to realize the miniaturization of the bulk acoustic wave resonator.

[0029] Further, the capacitance of the capacitor structure 30 can be adjusted, for example, by changing the depth of the recess to make it larger or smaller, changing the distance between the capacitor electrode 32 and the top electrode 31 to adjust the capacitance of the capacitor structure 30, or changing the opposite area between the capacitor electrode 32 and the top electrode 31 to adjust the capacitance of the capacitor structure 30.

[0030] 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.

[0031] 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.

[0032] like Figure 2 As 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.

[0033] 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.

[0034] like Figure 4As 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.

[0035] 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.

[0036] 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.

[0037] As Figure 1 shown in the application, for the interconnection wire of the bulk acoustic wave resonator, a first via hole 21 can also be arranged in the piezoelectric layer 20, the first via hole 21 penetrates the piezoelectric layer 20, and after the top electrode film is patterned, the top electrode film forms three independent parts, which are the top electrode 31, the planar inductor 34 and the transition electrode 35, the three of which do not form an electrical connection relationship with each other, the transition electrode 35 is in conduction with the bottom electrode 33 through the first via hole 21, and at the same time, a second via hole 61 is formed in the cover plate 60 and / or the dielectric layer 80, the first via hole 21 and the second via hole 61 are both filled with metal materials, thereby the bottom electrode 33 can be conducted to the outside of the cover plate 60 through the first via hole 21, the transition electrode 35 and the second via hole 61, the capacitor electrode 32 and the top electrode 31 can be conducted to the outside of the cover plate 60 through the corresponding second via hole 61, and the planar inductor 34 can be conducted to the outside of the cover plate 60 through the corresponding second via hole 61, a plurality of pads 70 are arranged on the side of the cover plate 60 away from the piezoelectric layer 20, the plurality of pads 70 correspond one-to-one to the second via holes 61, so that the signal input or output of the planar inductor 34, the top electrode 31 and the bottom electrode 33, and the capacitor structure 30 can be realized.

[0038] As Figure 6 shown, the application further provides a bulk acoustic wave filter, which comprises the bulk acoustic wave resonator described above, 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 ladder-shaped filter.

[0039] The application further provides a preparation method of the bulk acoustic wave resonator, which comprises: Step S1: providing a first substrate 100.

[0040] The first substrate 100 can be made of silicon, silicon carbide, spinel or sapphire, etc.

[0041] Step S2: as Figure 7a and Figure 7b , a bottom electrode film, a piezoelectric layer 20 and a top electrode film are sequentially formed on the first substrate 100, and the top electrode film is patterned to form a top electrode 31 and a planar inductor 34.

[0042] The bottom electrode thin film is formed on the first substrate 100, the bottom electrode 33 can adopt PVD (magnetic sputtering) process, the bottom electrode 33 and the top electrode 31 can adopt one or more metals with good conductivity selected from Mo, Au, Ag, Cu, Al, Ti and W, the piezoelectric layer 20 can adopt AlN (aluminum nitride), AlScN (scandium-doped aluminum nitride), LiTa03 (lithium tantalate) or LiNb03 (lithium niobate) and the like, and after the top electrode thin film is formed, the top electrode thin film is patterned by photolithography and etching process to form the patterned top electrode 31 and the planar inductor 34.

[0043] Step S3: as Figure 7c The 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, and the capacitor electrode 32 is filled in the groove to form the capacitor structure 30 with the top electrode 31, wherein the bulk acoustic wave resonator includes an active area A1 and a non-active area A2 at least partially surrounding the active area A1, the planar inductor 34 and the capacitor structure 30 are located in the non-active area A2 and are respectively located on both sides of the active area A1.

[0044] The dielectric layer 80 is formed on the top electrode 31 and the planar inductor 34, and the dielectric layer 80 is patterned to form an opening in the active area A1 corresponding to the position of the dielectric layer 80, and a groove in the position of the non-active area A2, and the opening and the groove can be formed on the dielectric layer 80 by photolithography and etching process, and the capacitor electrode 32 is filled in the groove by conductive glue of one or more metals selected from Mo, Au, Ag, Cu, Al, Ti and W, wherein at least part of the capacitor electrode 32 overlaps with the edge of the top electrode 31 in the longitudinal direction, so that the capacitor electrode 32 and the top electrode 31 can respectively serve as one of the plates of the parallel-plate capacitor to form the capacitor structure 30.

[0045] By simultaneously integrating the capacitor and the inductor in the bulk acoustic wave resonator, the device size can be greatly reduced, which is conducive to the miniaturization of the radio frequency device, and by using 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 the same process can be used, which not only reduces the device size, but also simplifies the process. In addition, since the capacitor and the inductor are respectively located on both sides of the active area A1, i.e. the non-active area A2 outside the active area A1 is used as the layout position of the capacitor and the inductor, which makes full use of the peripheral space of the resonator.

[0046] Step S4: as Figure 7d The second substrate 200 is covered on the capacitor electrode 32 and the dielectric layer 80.

[0047] The second substrate 200 can be made of silicon, silicon carbide, spinel or sapphire, etc.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] The third substrate 300 can be made of silicon, silicon carbide, spinel or sapphire, etc.

[0054] 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.

[0055] The second through holes 61 are arranged on the second substrate 200, and the second through holes 61 can be filled with materials such as Cu, Al, Ag, etc. The number of the second through holes 61 can be determined according to actual needs. For example, since the planar inductor 34 has an input end and an output end, the planar inductor 34 needs to correspond to two second through holes 61. Since the top electrode 31 corresponds to one second through hole 61, the capacitor structure 30 only needs one second through hole 61. Among the two second through holes 61 corresponding to the planar inductor 34, one needs to penetrate the second substrate 200 and be in conduction with the input end of the planar inductor 34, and the other second through hole 61 needs to penetrate the second substrate 200 and extend to the bottom of the dielectric layer 80 and be in conduction with the output end of the planar inductor 34. Similarly, the second through hole 61 corresponding to the top electrode 31 penetrates the second substrate 200 and extends to the bottom of the dielectric layer 80 and is in conduction with the top electrode 31. The second through hole 61 corresponding to the capacitor electrode 32 needs to penetrate the second substrate 200 and be in conduction with the capacitor electrode 32.

[0056] Step S9: as Figure 7h A pad 70 is formed on the side of the second substrate 200 away from the third substrate 300 and connected to the second through hole 61, and the second through hole 61 is in conduction with the planar inductor 34, the first through hole 21, the top electrode 31, the capacitor electrode 32, and the corresponding pad 70.

[0057] The pad 70 is formed on the upper surface of the second substrate 200, and the pad 70 is in conduction with the second through hole 61, so as to serve as the interconnection line of the planar inductor 34, the bottom electrode 33, the top electrode 31, and the capacitor electrode 32, and transmit signals as the input or output end of the capacitor structure 30, the top electrode 31, and the bottom electrode 33, and the planar inductor 34.

[0058] Step S31: forming a groove on the side of the dielectric layer 80 away from the top electrode 31, comprising: forming a groove on the side of the dielectric layer 80 away from the top electrode 31, or forming a groove on the side of the second substrate 200 close to the piezoelectric layer 20, or forming a first groove 322 on the side of the dielectric layer 80 away from the top electrode 31, and forming a second groove 321 on the side of the second substrate 200 close to the piezoelectric layer 20, and the first groove 322 and the second groove 321 form a groove.

[0059] In the present application, the groove can be arranged at different suitable positions, that is, the groove can be arranged on the dielectric layer 80 alone, or arranged on the second substrate 200 alone, or arranged on the second substrate 200 and the dielectric layer 80 simultaneously.

[0060] It should be noted that, in the present document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0061] Finally, it should be noted that the above-mentioned merely preferred embodiments of the present application, and are not used to limit the present application, although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A highly integrated bulk acoustic resonator characterized in that, The bulk acoustic wave resonator further comprises a substrate, a bottom electrode, a piezoelectric layer and a top electrode which are arranged in a stack along a longitudinal direction, and further comprises a planar inductor, a dielectric layer and a capacitor electrode, the planar inductor is in the same layer as the top electrode, the dielectric layer is located on a side of the planar inductor and the top electrode away from the piezoelectric layer, and the capacitor electrode is arranged on a 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 area and are respectively located on two sides of the active area.

2. The highly integrated bulk acoustic resonator of claim 1, wherein, The bulk acoustic wave resonator further comprises a cover plate which is stacked on the dielectric layer, and a recess is arranged on a side of the dielectric layer away from the top electrode and / or a side of the cover plate close to the piezoelectric layer, and the capacitor electrode is arranged in the recess.

3. The highly integrated bulk acoustic resonator of claim 2, wherein, The capacitor electrode comprises conductive glue, the recess is arranged on the side of the dielectric layer away from the top electrode, and the conductive glue is filled in the recess and simultaneously bonded to the side of the cover plate close to the piezoelectric layer and a side wall of the recess, or the capacitor electrode comprises conductive glue, the recess is arranged on the side of the cover plate close to the piezoelectric layer, and the conductive glue is filled in the recess and simultaneously bonded to the side of the dielectric layer away from the top electrode and a side wall of the recess.

4. The highly integrated bulk acoustic resonator of claim 2, wherein, The capacitor electrode comprises conductive glue, the recess comprises a first recess and a second recess, the first recess is arranged on the side of the dielectric layer away from the top electrode, the second recess is arranged on the side of the cover plate close to the piezoelectric layer, the first recess and the second recess are communicated, and the conductive glue is filled in the recess.

5. The highly integrated bulk acoustic resonator of claim 4, wherein, The first recess and the second recess are staggered with each other.

6. A highly integrated bulk acoustic resonator characterized by, The bulk acoustic wave resonator further comprises a substrate, a bottom electrode, a piezoelectric layer and a top electrode which are arranged in a stack along a longitudinal direction, and further comprises a first capacitor and a second capacitor, one of the plates of the first capacitor and one of the plates of the second capacitor are in the same layer as the top electrode, and the bulk acoustic wave resonator further comprises a dielectric layer which covers the top electrode, the other plate of the first capacitor and the other plate of the second capacitor are located on a side of the dielectric layer away from the top electrode, and the first capacitor and the second capacitor are located in the non-active area and are respectively located on two sides of the active area.

7. A bulk acoustic wave filter characterized by, The bulk acoustic wave resonator comprises any one of claims 1-6.

8. A method of fabricating a bulk acoustic resonator, characterized by, The bulk acoustic wave resonator comprises: providing a first substrate; forming a bottom electrode thin film, a piezoelectric layer and a top electrode thin film on the first substrate in sequence, and patterning the top electrode thin film to form a top 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 recess on a side of the dielectric layer away from the top electrode, and a capacitor electrode is filled in the recess to form a capacitor structure with the top electrode, wherein the bulk acoustic wave resonator comprises an active region and a non-active region at least partially surrounding the active region, and the planar inductor and the capacitor structure are located in the non-active region and are respectively located on two sides of the active region.

9. The production method according to claim 8, characterized by, The preparation method further comprises: 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 a bottom electrode; a first via hole is formed in the piezoelectric layer, and a conductive material is filled in the first via hole to conduct the bottom electrode and a part of the top electrode film, wherein the bottom electrode is not electrically connected with the top electrode; a third substrate is bonded on a side of the piezoelectric layer away from the top electrode; a plurality of second via holes are formed on the second substrate and / or the dielectric layer, and a conductive material is filled in the plurality of second via holes; a pad connected with the plurality of second via holes one by one is formed on a side of the second substrate away from the third substrate, and the plurality of second via holes respectively conduct the planar inductor, the first via hole, the top electrode, the capacitor electrode and the corresponding pad.

10. The method of claim 9, wherein, The step of forming the recess on the side of the dielectric layer away from the top electrode comprises: forming the recess on the side of the dielectric layer away from the top electrode, or forming the recess on a side of the second substrate close to the piezoelectric layer, or forming a first recess on a side of the dielectric layer away from the top electrode and forming a second recess on a side of the second substrate close to the piezoelectric layer, and the first recess and the second recess form the recess.

Images