JP7199757B2 - Bulk acoustic wave resonator, manufacturing method thereof, filter, radio frequency communication system - Google Patents

Description

TECHNICAL FIELD The present invention relates to the technical field of radio frequency communication, and more particularly to a bulk acoustic wave resonator and its manufacturing method and filter, radio frequency communication system.

Radio frequency (RF) communications, such as those used in cell phones, require the use of radio frequency filters, each of which transmits desired frequencies and limits all other frequencies. can be done. With the development of mobile communication technology, the amount of mobile data transferred is also increasing rapidly. Therefore, on the premise that frequency resources are limited and the need to use as few mobile communication devices as possible, it is difficult to improve the transmission power of wireless power transmission devices such as radio base stations, micro base stations or repeaters. , becomes a matter of consideration and also means that the filter power requirements in the front-end circuits of mobile communication devices are also high.

Conventionally, high-power filters in devices such as wireless base stations are mainly cavity filters, whose power reaches 100 watts, but the size of such filters is too large. Some devices use dielectric filters, the average power of which can reach 5 Watts or more, and the size of this filter is also large. Due to their large size, these two filters cannot be integrated into a radio frequency front-end chip.

As MEMS technology matures, filters composed of bulk acoustic wave (BAW) resonators can successfully overcome the existing deficiencies of the above two filters. Bulk acoustic wave resonators have volume advantages incomparable with ceramic dielectric filters, operating frequency and power capacity advantages incomparable with surface acoustic wave (SAW) resonators, and are a trend of current wireless communication systems. It has become.

The main body of the bulk acoustic wave resonator has a “sandwich” structure consisting of a bottom electrode, a piezoelectric thin film, and a top electrode. A standing wave is formed in the form of an acoustic wave in a filter composed of acoustic wave resonators. Since the speed of acoustic waves is five orders of magnitude smaller than that of electromagnetic waves, the size of filters composed of bulk acoustic wave resonators is smaller than that of conventional dielectric filters.

The working principle of one type of cavity bulk acoustic wave resonator is to use acoustic waves to reflect at the interface between the bottom electrode or support layer and the air, confining the acoustic waves to the piezoelectric layer to achieve resonance. It has advantages such as high Q factor, low insertion loss, and integrability, and is widely adopted.

However, conventionally fabricated cavity-type bulk acoustic wave resonators cannot further improve their quality factor (Q) and meet the demands of high-performance radio frequency systems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bulk acoustic wave resonator, a method for manufacturing the same, a filter, and a radio frequency communication system that can improve the quality factor and the performance of the device.

To achieve the above object, the present invention provides a bulk acoustic wave resonator comprising:
a substrate;
a bottom electrode layer provided on the substrate, wherein a cavity is formed between the bottom electrode layer and the substrate; the bottom electrode layer has a bottom electrode protrusion; a bottom electrode layer located in the region of the cavity and protruding away from the bottom surface of the cavity;
a piezoelectric resonance layer formed on the bottom electrode layer above the cavity;
a top electrode layer formed on the piezoelectric resonance layer, the top electrode layer having a top electrode protrusion, the top electrode protrusion being located in the region of the cavity and the bottom surface of the cavity; Both the top electrode protrusion and the bottom electrode protrusion are located in the cavity region on the outer periphery of the piezoelectric resonance layer, and the bottom electrode protrusion and the top electrode protrusion are both located in the piezoelectric resonance layer. A bulk acoustic wave resonator is provided comprising: a top electrode layer extending circumferentially around the layer, at least a portion of which is opposed to the top electrode layer.

The invention further provides a filter comprising at least one bulk acoustic wave resonator according to the invention.

The invention further provides a radio frequency communication system comprising at least one filter according to the invention.

The present invention is a method of manufacturing a bulk acoustic wave resonator, comprising:
providing a substrate and forming a first sacrificial layer having a first sacrificial protrusion on a portion of the substrate;
forming a bottom electrode layer on the first sacrificial layer, the portion of the bottom electrode layer covered by the surface of the first sacrificial protrusion forming a bottom electrode protrusion;
forming a piezoelectric resonance layer on the bottom electrode layer and exposing the bottom electrode protrusion from the piezoelectric resonance layer;
forming a second sacrificial layer having a second sacrificial protrusion in a region exposed from the perimeter of the piezoelectric resonance layer;
forming a top electrode layer on the piezoelectric resonance layer and a second sacrificial layer partly around the piezoelectric resonance layer, the portion of the top electrode layer covered by the second sacrificial protrusion forming a top electrode protrusion; forming;
removing the second sacrificial layer with second sacrificial protrusions and the first sacrificial layer with first sacrificial protrusions; removing the second sacrificial layer with second sacrificial protrusions and the first sacrificial protrusions; wherein the top electrode protrusion and the bottom electrode protrusion are both located in the cavity region on the outer periphery of the piezoelectric resonance layer, and the bottom electrode A protrusion and the top electrode protrusion both extend around the piezoelectric resonance layer in a peripheral direction, and at least a portion of both of them face each other. offer.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects.
1. When electrical energy is applied to the bottom electrode and the top electrode, the piezoelectric phenomenon induced in the piezoelectric resonance layer produces a desired longitudinal wave propagating in the thickness direction and an undesirable transverse wave propagating along the plane of the piezoelectric resonance layer. Then, the transverse wave is blocked by the bottom electrode projection and the top electrode projection on the cavity floating on the outer circumference of the piezoelectric resonance layer, is reflected by the region corresponding to the piezoelectric resonance layer, and further the transverse wave is transmitted to the film layer on the outer circumference of the cavity. This can improve the acoustic wave loss, improve the quality factor of the resonator, and ultimately improve the performance of the device.

2. The periphery of the piezoelectric resonance layer and the periphery of the cavity are separated from each other, that is, the piezoelectric resonance layer does not extend continuously above the substrate at the periphery of the cavity, and the effective operation of the bulk acoustic wave resonator The area can be completely confined to the cavity area, with both the bottom and top electrode bridges extending to only some sides of the cavity (i.e., the bottom and top electrode layers (without completely covering the cavity), thereby reducing the influence of the membrane layer around the cavity on the longitudinal vibrations induced in the piezoelectric resonant layer and improving performance.

3. Even if the bottom electrode protrusion and the top electrode protrusion have overlapping portions, there is a gap structure between the overlapping portions, which can greatly reduce the parasitic parameters, and the top electrode layer And problems such as electrical contact in the cavity region of the bottom electrode layer can be avoided, and the reliability of the device can be improved.

4. The overlapping portions of the bottom electrode bridge portion and the top electrode bridge portion with the cavity are all floating, and the bottom electrode bridge portion and the top electrode bridge portion are offset from each other (i.e., both do not overlap in the cavity region), which can greatly reduce the parasitic parameters and avoid problems such as leakage and short circuit caused by contact between the bottom electrode bridge and the top electrode bridge; Device reliability can be improved.

5. The bottom electrode bridge completely covers the cavity above the portion of the cavity in which it is located, thereby using a large area bottom electrode bridge to strongly attach to the membrane layer above it. provide good mechanical support, thereby avoiding the problem of device failure due to cavity collapse.

6. The top electrode protrusion surrounds the entire circumference of the top electrode resonance part, and the bottom electrode recess surrounds the entire circumference of the bottom electrode resonance part, which blocks transverse waves from the periphery of the piezoelectric resonance layer in all directions, and has a favorable quality factor. can be obtained.

7. The bottom electrode protruding portion, the bottom electrode resonant portion and the bottom electrode bridge portion are formed of the same film layer and have a uniform film thickness, and the top electrode protruding portion, the top electrode resonant portion and the top electrode bridge portion are formed of the same film. The film thickness is uniform, which simplifies the process and reduces the cost. To improve the reliability of a device without causing a situation in which the bottom electrode protrusion and the top electrode protrusion are cut off because the film thickness of the electrode protrusion is substantially the same as that of the other portions of the top electrode layer. can be done.

1 is a top structural schematic diagram of a bulk acoustic wave resonator according to an embodiment of the present invention; FIG. FIG. 2 is a schematic cross-sectional view taken along lines XX' and YY' in FIG. 1; FIG. 2 is a schematic cross-sectional view taken along lines XX' and YY' in FIG. 1; FIG. 4 is a top structural schematic diagram of a bulk acoustic wave resonator according to another embodiment of the present invention; FIG. 4 is a top structural schematic diagram of a bulk acoustic wave resonator according to another embodiment of the present invention; FIG. 4 is a top structural schematic diagram of a bulk acoustic wave resonator according to another embodiment of the present invention; FIG. 4 is a top structural schematic diagram of a bulk acoustic wave resonator according to another embodiment of the present invention; FIG. 4 is a top structural schematic diagram of a bulk acoustic wave resonator according to another embodiment of the present invention; 1 is a flow chart of a method for manufacturing a bulk acoustic wave resonator according to one embodiment of the present invention; It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. 1B is a schematic cross-sectional view along XX' in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to another embodiment of the present invention; FIG.

The technical solutions of the present invention are further described in detail below with reference to the drawings and specific embodiments. Based on the following description, the effects and features of the present invention will become clearer. It should be noted that the drawings are all in a greatly simplified form, imprecise proportions, and are merely for the purpose of providing an easy, clear and supplemental explanation of the embodiments of the present invention. Similarly, to the extent that the methods described herein include a series of steps, the order of these steps presented herein is not the only order in which these steps may be performed, and some said steps may include: Some other steps may be omitted and/or not described herein may be added to the method. Further, what is meant herein by "relatively offset" is that they do not overlap in the cavity area, ie their projections at the bottom of the cavity do not overlap.

1A to 1C, FIG. 1A is a top structural schematic diagram of a bulk acoustic wave resonator of one embodiment of the present invention, and FIG. 1B is a cross-sectional structural schematic diagram along XX' in FIG. FIG. 1C is a schematic cross-sectional view along line YY' in FIG. and layer 108 .

The substrate includes a base 100 and an etching protection layer 101 coated on the base 100 . The base 100 may be any suitable substrate known to those skilled in the art, such as silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III/V compound semiconductors, multilayer structures composed of these semiconductors, etc. May be one or Silicon on Insulator (SOI), Stacked Silicon on Insulator (SSOI), Stacked Silicon Germanium on Insulator (S-SiGeOI), Stacked Silicon Germanium on Insulator (SiGeOI) and Germanium on Insulator (GeOI), or Double Side Polished Wafers (DSP), ceramic-based such as aluminum oxide, Sekiei , or may be a glass base or the like. The material of the etching protection layer 101 may be any suitable dielectric material, including but not limited to at least one of silicon oxide, silicon nitride, silicon nitrogen oxide, silicon carbonitride, and the like. can't The etching protection layer, on the other hand, improves the structural stability of the finally manufactured bulk acoustic wave resonator, strengthens the isolation between the bulk acoustic wave resonator and the base 100, and reduces the resistivity requirements for the base 100. can be reduced while protecting other areas of the substrate from being etched during fabrication of the bulk acoustic wave resonator, thereby improving device performance and reliability.

A cavity 102 is formed between the bottom electrode layer 104 and the substrate. 1A-1C, in this embodiment, the cavity 102 may be formed by sequentially etching the thickness of the etching protection layer 101 and part of the base 100 by an etching process, and the bottom The whole becomes a groove structure recessed in the substrate. However, the technique of the present invention is not limited to this, and referring to FIG. 2E, in another embodiment of the present invention, the cavity 102 is followed by a sacrificial layer protruding from the etching protection layer 101 . Through the process of removing using a removing method, it may be formed above the top surface of the etching protection layer 101 , resulting in a cavity structure that protrudes over the surface of said etching protection layer 101 as a whole. Also, in this embodiment, the shape of the bottom surface of the cavity 102 may be rectangular, but in other embodiments of the present invention, the shape of the bottom surface of the cavity 102 may also be circular, elliptical, or other than rectangular. polygon (eg, pentagon, hexagon).

The piezoelectric resonant layer 1051, which may be called a piezoelectric resonant part, is located in the upper region of the cavity 102 (i.e., located within the region of the cavity 102) and corresponds to the effective working area of the bulk acoustic wave resonator. and is provided between the bottom electrode layer 104 and the top electrode layer 108 . The bottom electrode layer 104 includes a bottom electrode bridge portion 1040, a bottom electrode protrusion 1041, and a bottom electrode resonance portion 1042, which are connected in order. The top electrode layer 108 includes a top electrode bridge portion 1080, a top electrode protrusion, which are connected in order. 1081 and a top electrode resonant portion 1082 , and both the bottom electrode resonant portion 1042 and the top electrode resonant portion 1082 overlap the piezoelectric resonant layer 1051 , and the overlapping bottom electrode resonant portion 1042 , the piezoelectric resonant layer 1051 , and the top electrode resonant portion 1082 The corresponding region of the cavity 102 constitutes an effective operating region 102A of the bulk acoustic wave resonator, and the portion of the cavity 102 other than the effective operating region 102A is an ineffective region 102B. Located in the region 102A and separated from the film layers surrounding the cavity 102, the effective operating region of the bulk acoustic wave resonator can be completely restricted to the region of the cavity 102, and the piezoelectric The effect on longitudinal vibrations induced in the resonant layer can be reduced, the parasitic parameters induced in the dead region 102B can be reduced, and the performance of the device can be improved. The bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051, and the top electrode resonance portion 1082 all have flat structures with flat upper and lower surfaces, and the bottom electrode projecting portion 1041 is located at the outer periphery of the effective operation area 102A in the cavity 102B. The top electrode projecting portion 1081 is located above and electrically connected to the bottom electrode resonant portion 1042 and projects away from the bottom surface of the cavity, and the top electrode projecting portion 1081 is located above the cavity 102B on the outer periphery of the effective operating area 102A. It is positioned and electrically connected to the top electrode resonator 1082 and protrudes away from the bottom surface of the cavity 102 . The entire bottom electrode protrusion 1041 protrudes upward from the top surface of the bottom electrode resonance section 1042, the entire top electrode protrusion 1081 protrudes upward from the top surface of the top electrode resonance section 1082, and the top electrode protrusion 1081 protrudes upward from the top surface of the top electrode resonance section 1082. and the bottom electrode protrusion 1041 are both located in the cavity region (ie, 102B) on the outer periphery of the piezoelectric resonance layer 1051 . The bottom electrode protrusion 1041 and the top electrode protrusion 1081 may have a solid structure or a hollow structure, preferably a hollow structure, thereby forming the bottom electrode layer 104 and the top electrode layer 108 . The film thickness of the solid bottom electrode projecting portion 1041 can be made uniform, and separation of the bottom electrode resonant portion 1042 and the piezoelectric resonant layer 1051 due to the gravity of the solid bottom electrode projecting portion 1041 can be avoided. It avoids the collapsing deformation of the top electrode resonant part 1082 and the piezoelectric resonant layer 1051 and the bottom electrode resonant part 1042 caused by the protrusion 1081, and further improves the resonance coefficient. Both the bottom electrode resonance portion 1042 and the top electrode resonance portion 1082 are polygonal (the top surface and the bottom surface are both polygonal), and the shapes of the bottom electrode resonance portion 1042 and the top electrode resonance portion 1082 are may be similar (shown in FIGS. 2A-2B and 2D) or completely identical (shown in FIGS. 1A and 2C). The piezoelectric resonance layer 1051 has a polygonal structure similar to the shapes of the bottom electrode resonance part 1042 and the top electrode resonance part 1082 .

1A to 1C, in this embodiment, the bottom electrode layer 104, the piezoelectric resonance layer 1051 and the top electrode layer 108 constitute a "watch"-like film layer structure, and the bottom electrode bridge portion 1040 is the bottom electrode resonance layer. Aligned with one corner of portion 1042, with top electrode bridge portion 1080 aligned with one corner of top electrode resonator portion 1082, bottom electrode bridge portion 1040 and top electrode bridge portion 1080 form the two bands of the "watch". , and the bottom electrode projecting portion 1041 is provided along the side of the bottom electrode resonant portion 1042 and is provided only in a region where the bottom electrode bridge portion 1040 and the bottom electrode resonant portion 1042 are aligned. the top electrode projecting portion 1081 is provided along the side of the top electrode resonant portion 1082 and is provided only in a region where the top electrode bridge portion 1080 and the top electrode resonant portion 1082 are aligned, The bottom electrode protrusion 1041 and the top electrode protrusion 1081 correspond to the connection structure between the dial of a "watch" and two bands, and the bottom electrode resonance part 1042 and the piezoelectric resonance layer 1051 in the effective area 102A. , the lamination structure of the top electrode resonance part 1082 corresponds to the dial of a wrist watch, in which the band part is connected to the film layer on the substrate around the cavity, and the remaining parts are all connected through the cavity. separated from the film layer on the substrate surrounding the cavity. That is, in this embodiment, both the bottom electrode protrusion 1041 and the top electrode protrusion 1081 extend surrounding the piezoelectric resonance layer 1051 in the peripheral direction. The protrusions 1081 are respectively surrounded by only a part of the sides of the piezoelectric resonance layer 1051 along the peripheral direction of the piezoelectric resonance layer 1051, and refer to the plane where the piezoelectric resonance layer 1051 is located. The bottom electrode protrusions 1041 are located on both sides of the piezoelectric resonance layer 1051 and completely face each other, thereby realizing a certain transverse wave blocking effect, and the top electrode bridge part 1080 and the bottom electrode bridge part 1040 It contributes to a reduction in the area of the uncovered dead area 102B, which in turn contributes to a reduction in the size of the device, which in turn contributes to a reduction in the area of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040, which further reduces the parasitic parameters. reduce and improve the electrical performance of the device. The bottom electrode bridge portion 1040 is electrically connected to the side of the bottom electrode projecting portion 1041 facing away from the bottom electrode resonance portion 1042 , and the bottom electrode projecting portion 1041 is connected to the bottom electrode projecting portion 1041 from above the bottom electrode projecting portion 1041 . After passing above an outwardly floating cavity (that is, 102B), it extends to above a portion of the etching protection layer 101 at the outer periphery of the cavity 102, and the top electrode bridge portion 1080 is connected to the top electrode. A cavity (that is, 102B) that is electrically connected to the side of the protruding portion 1081 opposite to the top electrode resonant portion 1082 and floats from above the top electrode protruding portion 1081 to the outside of the top electrode protruding portion 1081. After passing above, it extends to above a part of the etching protection layer 101 at the outer periphery of the cavity 102, and the bottom electrode bridge part 1040 and the top electrode bridge part 1080 connect two opposite sides of the cavity 102. The bottom electrode bridge portion 1040 and the top electrode bridge portion 1080 are offset from each other (i.e., do not overlap) in the cavity 102 area at this time, and this can reduce parasitic parameters, avoid problems such as leaks and short circuits caused by contact between the bottom electrode bridge and the top electrode bridge, and improve device performance. The bottom electrode bridge portion 1040 is used to transfer a corresponding signal to the bottom electrode resonance portion 1042 via the bottom electrode projection portion 1041 by connecting the corresponding signal line, and the top electrode bridge portion 1080 is , is used to transfer the corresponding signal to the top electrode resonator 1082 via the top electrode protrusion 1081 by connecting the corresponding signal line, so that the bulk acoustic wave resonator can operate normally. Specifically, by applying a time-varying voltage to the bottom electrode resonance section 1042 and the top electrode resonance section 1082 via the bottom electrode bridge section 1040 and the top electrode bridge section 1080, respectively, the longitudinal extension mode or , excites a “piston” mode, the piezoelectric resonant layer 1051 converts the energy in the form of electrical energy into longitudinal waves, generating parasitic transverse waves in the process, and the bottom electrode protrusion 1041 and the top electrode protrusion 1081 are coupled to these can be blocked from propagating to the film layer at the outer periphery of the cavity and confined to the area of the cavity 102, thereby avoiding energy loss due to the shear wave and improving the quality factor.

Preferably, the line widths of the top electrode protrusion 1081 and the bottom electrode protrusion 1041 are the minimum line widths allowed for the corresponding processes, and the horizontal distance between the bottom electrode protrusion 1041 and the piezoelectric resonance layer 1051 and The horizontal distance between the top electrode protrusion 1081 and the piezoelectric resonance layer 1051 is the minimum distance allowed for the corresponding process, so that the top electrode protrusion 1081 and the bottom electrode protrusion 1041 form a predetermined transverse wave. A blocking effect can be realized, and the device area can be reduced.

Further, the sidewall of the top electrode protrusion 1081 is a sidewall inclined with respect to the top surface of the piezoelectric resonance layer 1051, and as shown in FIG. 1B, the top electrode protrusion 1081 is XX′ in FIG. 1A. The cross section along the line is a trapezoid or a trapezoid-like shape, and the angles β1 and β2 between the two side walls of the top electrode protrusion 1081 and the top surface of the piezoelectric resonance layer 1051 are both 45 degrees. This avoids the side wall of the top electrode protrusion 1081 being too vertical, causing the top electrode protrusion 1081 to be cut, and further affecting the effect of transferring the signal to the top electrode resonance section 1082. Also, the thickness uniformity of the entire top electrode layer 108 can be further improved, and the sidewalls of the bottom electrode protrusion 1041 are sloped sidewalls with respect to the bottom surface of the piezoelectric resonance layer 1051, as shown in FIG. 1B. , the cross section of the bottom electrode protrusion 1041 along line XX' in FIG. Both of the angles α1 and α2 between the bottom surface of the layer 1051 and the bottom surface are 45 degrees or less. It is possible to avoid affecting the effect of transferring the signal to the resonator 1042 and further improve the thickness uniformity of the bottom electrode layer 104 .

In one preferred embodiment of the present invention, the bottom electrode resonator portion 1042, the bottom electrode protrusion portion 1041 and the bottom electrode bridge portion 1040 are formed in the same film layer manufacturing process (i.e., the same film layer manufacturing process). The electrode resonance part 1082, the top electrode protrusion part 1081, and the top electrode bridge part 1080 are formed in the same film layer manufacturing process (that is, the same film layer manufacturing process). and the bottom electrode bridge portion 1040 are integrally manufactured film layers, and the top electrode resonance portion 1082, the top electrode protrusion portion 1081 and the top electrode bridge portion 1080 are integrally manufactured film layers, whereby To simplify the process and reduce the cost, the film layer materials for fabricating the bottom electrode resonator 1042, the bottom electrode protrusion 1041 and the bottom electrode bridge 1040, and the top electrode resonator 1082, the top electrode protrusion 1081 and the top The film layer material for fabricating the electrode bridge portion 1080 may be any suitable conductive material or semiconductor material known in the art, respectively, and the conductive material may be a metal having electrical conductivity. The material may be aluminum (Al), copper (Cu), platinum (Pt), gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), rhenium (Re), palladium (Pd), rhodium (Rh), and ruthenium (Ru), and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, or the like. In another embodiment of the present invention, the bottom electrode resonance part 1042, the bottom electrode protrusion part 1041 and the bottom electrode bridge part 1040 can be formed by different film layer manufacturing processes, subject to process cost and process technology. Well, the top electrode resonator portion 1082, the top electrode protrusion portion 1081 and the top electrode bridge portion 1080 may be formed by different layer manufacturing processes.

2A-2D, in order to further improve the transverse wave blocking effect, the bottom electrode protrusion 1041 extends to more continuous sides of the bottom electrode resonator 1042, and the top electrode protrusion 1081 extends to the top. It extends to more continuous sides of the electrode resonator 1082 . For example, referring to FIG. 2A, the projections of bottom electrode protrusion 1041 and top electrode protrusion 1081 at the bottom surface of cavity 102 may be just connected or nearly connected, i.e., bottom electrode protrusion 1041 and the top electrode protrusion 1081 at the bottom of the cavity 102 may form a completely closed ring or a nearly closed ring, whereby the bottom electrode protrusion 1041 and the top electrode protrusion 1081 By fitting the piezoelectric resonance layer 1051, transverse waves can be shielded from the entire circumference of the piezoelectric resonance layer 1051. Alternatively, the ring formed by combining the two may be evenly divided (at this time, the bottom electrode protrusion 1041 and the top electrode protrusion 1081 are positioned on both sides of the piezoelectric resonance layer 1051, respectively, and the entire portion is are completely opposed to each other), and the division may not be uniform (at this time, the bottom electrode protrusion 1041 and the top electrode protrusion 1081 are positioned on both sides of the piezoelectric resonance layer 1051, respectively, and only a portion of the bottom electrode protrusion 1041 and the top electrode protrusion 1081 opposite). For example, referring to FIG. 2B, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082, and the bottom electrode resonance portion 1042 all have a pentagonal planar structure, and the area of the piezoelectric resonance layer 1051 is the smallest. The portion 1082 is larger than that, and the area of the bottom electrode resonant portion 1042 is the largest, and the bottom electrode projecting portion 1041 is provided along each side of the bottom electrode resonant portion 1042 and connected to each side, A part or all of the projection of the boundary connected from the top electrode bridge portion 1080 of the top electrode protrusion 1081 on the bottom surface of the cavity 102 is exposed from the projection of the bottom electrode protrusion 1041 on the bottom surface of the cavity 102. The top electrode projecting portion 1081 is provided along each side of the top electrode resonant portion 1082 and connected to each side, and is connected to the bottom electrode bridge portion 1040 of the bottom electrode projecting portion 1041 . Some or all projections of the boundary at the bottom surface of the cavity 102 are exposed from the projection of the top electrode protrusion 1081 at the bottom surface of the cavity 102 , thereby forming the bottom electrode protrusion 1041 and the top electrode bridge 1080 . do not overlap, the top electrode protrusion 1081 and the bottom electrode bridge 1040 do not overlap, further reducing the parasitic parameter, and the bottom electrode protrusion 1041 and the top electrode protrusion 1081 In other words, the bottom electrode protrusion 1041 and the top electrode protrusion 1081 are completely displaced in the direction perpendicular to the piezoelectric resonance layer 1051, or , are only partially aligned above and below (not in contact under any circumstances to ensure electrical isolation between the top electrode layer 108 and the bottom electrode layer 104), and all parts face each other, so that the bottom electrode protrusion 1041 can partially surround the top electrode protrusion 1081 in the projection structure at the bottom surface of the cavity, and thus the bottom electrode protrusion 1041 and the By fitting the top electrode projecting portion 1081, transverse waves can be shielded from the entire periphery of the piezoelectric resonance layer 1051, and a request for alignment between the bottom electrode projecting portion 1041 and the top electrode projecting portion 1081 can be made. can be reduced, contributing to a reduction in the manufacturing difficulty of the process. For example, referring to FIG. 2C, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082, and the bottom electrode resonance portion 1042 all have a pentagonal planar structure, and the area of the piezoelectric resonance layer 1051 is the smallest. The portion 1082 and the bottom electrode resonance portion 1042 have the same or substantially the same area, shape, etc., and the bottom electrode projection portion 1041 surrounds the entire periphery of the bottom electrode resonance portion 1042 and the top electrode projection portion 1081 surrounds the entire circumference of the top electrode resonance portion 1082 , and projections of the bottom electrode projection portion 1041 and the top electrode projection portion 1081 on the bottom surface of the cavity 102 are overlapped, but there is a gap between the top electrode layer 108 and the bottom electrode layer 104 . In order to ensure electrical isolation, the projections of the top electrode resonator 1082 and the bottom electrode resonator 1042 on the bottom surface of the cavity 102 overlap under no circumstances so that they are not in contact, thereby allowing different heights to be vertically positioned. Since both the bottom electrode protrusion 1041 and the top electrode protrusion 1081 have a closed annular shape, transverse waves of different heights generated in the piezoelectric resonance layer 1051 can be blocked. That is, when the bottom electrode projecting portion 1041 extends to more continuous sides of the bottom electrode resonant portion 1042 and the top electrode projecting portion 1081 extends to more continuous sides of the top electrode resonant portion 1082. , the bottom electrode protrusion 1041 and the top electrode protrusion 1081 both extend around the piezoelectric resonance layer 1051 in the peripheral direction, and the bottom electrode protrusion 1041 and the top electrode protrusion 1081 are respectively along the peripheral direction of the piezoelectric resonant layer 1051, partially encircling the periphery of the piezoelectric resonant layer 1051 (shown in FIGS. 2A-2B), where at least both the top electrode protrusion 1081 and the bottom electrode protrusion 1041 are The bottom electrode protrusion 1041 and the top electrode protrusion 1081 partially face each other, or respectively surround the entire periphery of the piezoelectric resonance layer 1051 along the peripheral direction of the piezoelectric resonance layer 1051 (shown in FIG. 2C), At this time, both the top electrode protrusion 1081 and the bottom electrode protrusion 1041 face each other.

2A-2D, in these embodiments of the present invention, the bottom electrode bridge portion 1040 includes at least one side of the bottom electrode protrusion 1041 facing away from the bottom electrode resonance portion 1042, or at least After passing above the cavity (that is, 102B) that is electrically connected to one corner and floats outside the bottom electrode protrusion 1041 from the corresponding side of the bottom electrode protrusion 1041, the The top electrode bridge portion 1080 extends to above a portion of the etching protection layer 101 on the outer periphery, and the top electrode bridge portion 1080 extends from at least one side of the top electrode protrusion portion 1081 facing away from the top electrode resonance portion 1082 or at least one side of the top electrode resonance portion 1082 . After passing above the cavity (that is, 102B) that is electrically connected to one corner and floats outside the top electrode protrusion 1081 from the top electrode protrusion 1081, a part of the outer periphery of the cavity 102 Extending above the etching protection layer 101, the projections of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 on the bottom surface of the cavity 102 may just be connected or separated from each other. , whereby the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 are offset from each other in the region of the cavity 102 without overlapping. For example, as shown in FIGS. 1A and 2A-2C, the bottom electrode bridge portion 1040 extends above a portion of the substrate at the perimeter of only one side of the cavity 102 to provide the top electrode bridge. A portion 1080 extends above a portion of the substrate at the perimeter of only one side of the cavity 102 , and at the bottom surface of the cavity 102 between the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 . are separated from each other, thereby avoiding the introduction of parasitic parameters and problems such as leaks and shorts that can be caused when the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 overlap. However, preferably, referring to FIG. 2D, when the bottom electrode protrusions 1041 are provided along a plurality of continuous sides of the bottom electrode resonance part 1042, the bottom electrode bridge part 1040 is connected to the bottom electrode protrusions 1041 , and extends continuously to the substrate at the outer periphery of the cavity 102, whereby the bottom electrode bridge portion 1040 is provided along all sides facing away from the bottom electrode resonance portion 1042 of the cavity. 102, i.e., the bottom electrode bridge portion 1040 then extends above the portion of the cavity in which it is located. completely covers the cavity 102 at , thereby increasing the supporting force of the effective working area 102A to the membrane layer by laying down the large-area bottom electrode bridge portion 1040 to prevent the cavity 102 from collapsing. More preferably, when the bottom electrode bridge portion 1040 extends above a portion of the substrate in more directions at the outer periphery of the cavity 102, the top electrode bridge portion 1080 extends from the outer periphery of the cavity 102. For example, if the top surface shape of the cavity 102 is rectangular, the top electrode bridge portion 1080 extends to the outer periphery of only one side of the cavity 102. , and the bottom electrode bridge portion 1040 extends to the other three sides of the cavity 102, where the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 and are just connected or separated from each other, i.e., the bottom electrode bridge portion 1040 is then above the portion of the cavity in which it is located. , completely covers the cavity 102 and does not overlap the top electrode bridge portion 1080 in the width direction of the top electrode bridge portion 1080 . This avoids introducing too many parasitic parameters when providing a large area of the top electrode bridge, which vertically overlaps structures such as the bottom electrode bridge, further improving the electrical performance and reliability of the device. can be improved.

In each embodiment of the present invention, when the top surface shape of the cavity 102 is polygonal, at least one side of the cavity 102 is exposed from each of the bottom electrode bridge portion 1040 and the top electrode bridge portion 1080, thereby , the bottom electrode resonance portion 1042 to which the bottom electrode projection portion 1041 is connected, and the top electrode resonance portion 1082 to which the top electrode projection portion 1081 is connected, each has at least one end completely floating, thus forming the invalid region 102B. In addition, parasitic parameters such as parasitic capacitance generated in the invalid region 102B are reduced, thereby improving the performance of the device. Preferably, the bottom electrode protrusion 1041 is offset from at least the top electrode bridge 1080 above the cavity 102 (i.e., they do not overlap in the cavity area), and the top electrode protrusion 1081 is aligned with the cavity. 102 above at least the bottom electrode bridge portion 1040 mutually offset (i.e., they do not overlap in the cavity area), the projection of the top electrode protrusion 1081 and the bottom electrode protrusion 1041 on the bottom surface of the cavity 102 are just connected, mutually displaced, or partially overlapped, and the overlapping portions of the top electrode protrusion 1081 and the bottom electrode protrusion 1041 do not make electrical contact. This further reduces the parasitic parameters such as parasitic capacitance generated in the invalid region 102B, avoids the occurrence of a short circuit between the top electrode layer and the bottom electrode layer, and improves the performance of the device.

In addition, in order to realize the optimum transverse wave blocking effect and contribute to the fabrication of a small size device, it is preferable that the top electrode protrusion 1081 and the bottom electrode protrusion 1041 are closer to the effective operation area 102A. Preferably, the line widths of the top electrode protrusion 1081 and the bottom electrode protrusion 1041 are the minimum line widths allowed for the corresponding processes, The horizontal distances between the electrode protrusions 1081 and bottom electrode protrusions 1041 and the effective operating area 102A (that is, the piezoelectric resonance layer 1051) are respectively the minimum distances allowed for the corresponding processes.

In each of the above embodiments, the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042 have similar or the same shape and have the same area, or the area of the bottom electrode resonance portion 1042 is the same as that of the top electrode. Although the area of the resonator 1082 is larger, the technical solution of the present invention is not limited to this. In other embodiments of the present invention, the shapes of the top electrode resonating portion 1082 and the bottom electrode resonating portion 1042 may not be similar, but the top electrode protrusion 1081 and the bottom electrode protrusion 1041 are shaped like piezoelectric resonators. It preferably conforms to the shape of layer 1051 and can extend along at least one side of piezoelectric resonant layer 1051 . Furthermore, research has found that most of the parasitic transverse waves in bulk acoustic wave resonators are transmitted through the connecting structure between the film layers on the effective working area 102A and the substrate at the periphery of the cavity, thus , in each embodiment of the present invention, the area (i.e., line width) of the top electrode bridge portion 1080 is minimized, and the area (i.e., line width) of the bottom electrode bridge portion 1040 is minimized, provided that the membrane layers of the effective active area 102A can be effectively supported. The area (ie line width) can be controlled as much as possible.

An embodiment of the invention further provides a filter comprising at least one bulk acoustic wave resonator as described in any of the embodiments of the invention above.

An embodiment of the invention further provides a radio frequency communication system comprising at least one filter according to an embodiment of the invention.

Referring to FIG. 3, one embodiment of the present invention is a method of manufacturing a bulk acoustic wave resonator of the present invention (eg, the bulk acoustic wave resonator shown in FIGS. 1A-2D) comprising:
step S1 of providing a substrate and forming a first sacrificial layer having a first sacrificial protrusion on a portion of said substrate;
step S2 of forming a bottom electrode layer on the first sacrificial layer, the portion of the bottom electrode layer covered by the surface of the first sacrificial protrusion forming a bottom electrode protrusion;
a step S3 of forming a piezoelectric resonance layer on the bottom electrode layer and exposing the bottom electrode protrusion from the piezoelectric resonance layer;
step S4 of forming a second sacrificial layer having a second sacrificial protrusion in a region exposed from the periphery of the piezoelectric resonance layer;
forming a top electrode layer on the piezoelectric resonance layer and a second sacrificial layer partly around the piezoelectric resonance layer, the portion of the top electrode layer covered by the second sacrificial protrusion forming a top electrode protrusion; a forming step S5;
removing the second sacrificial layer having second sacrificial protrusions and the first sacrificial layer having first sacrificial protrusions, and the second sacrificial layer having second sacrificial protrusions and having first sacrificial protrusions; forming a cavity at the location of the first sacrificial layer, wherein the top electrode protrusion and the bottom electrode protrusion are both located in the cavity region on the outer periphery of the piezoelectric resonance layer, and the bottom electrode protrusion is and a step S6 in which both the top electrode protrusions extend around the piezoelectric resonance layer in a peripheral direction, and at least a part of the two face each other.

1A, 1B and 4A-4B, in step S1 of the present embodiment, the first sacrificial layer is formed into a part of the substrate by etching the substrate to form grooves and filling the grooves with material. The specific realization process formed above includes the following.

First, referring to FIGS. 1A and 4A, a substrate is provided, specifically a base 100 is provided, and the base 100 is coated with an etching protection layer 101 . The etching protection layer 101 is formed by any suitable process method, such as thermal treatment methods such as thermal oxidation, thermal nitridation, thermal oxynitridation, or deposition methods such as chemical vapor deposition, physical vapor deposition or atomic layer deposition. , may be formed on the base 100 . Moreover, the etching thickness of the protective layer 101 may be reasonably set according to the actual device process needs, and is not specifically limited here.

Subsequently, referring to FIGS. 1A, 1B and 4A, at least one groove 102' is formed by etching the substrate by a photo-etching and etching process. The etching process may be a wet etching process or a dry etching process, preferably using a dry etching process, the dry etching process being reactive ion etching (RIE), ion beam etching, plasma etching, or laser cutting. Including but not limited to: The depth and shape of the groove 102' are all determined by the depth and shape of the cavity required for the bulk acoustic wave resonator to be manufactured, and the cross-sectional shape of the groove 102' is rectangular. In embodiments, the cross-section of groove 102' may also be any other suitable shape, such as circular, elliptical, or other polygonal shapes other than rectangular (pentagons, hexagons, etc.).

1A, 1B and 4B, a first sacrificial layer 103 may be filled into the trench 102' by a process such as vapor deposition, thermal oxidation, spin coating or epitaxial growth, and 1 sacrificial layer 103 may be selected semiconductor material, dielectric material or photoresist material different from the base 100 and etching protection layer 101, for example, if the base 100 is Si-based, the first sacrificial layer 103 may be Ge, in which case the formed first sacrificial layer 103 is further covered by the etching protection layer 101 at the periphery of the trench or the top surface is etched around the trench. by planarizing the top of the first sacrificial layer 103 to the top surface of the etching protection layer 101 by a chemical mechanical planarization (CMP) process, which may be higher than the top surface of the protection layer 101 . , the first sacrificial layer 103 is positioned only in the groove 102', and the top surface of the first sacrificial layer 103 is flush with the top surface of the surrounding etching protection layer 101, thereby enabling subsequent etching. provides a flat process surface for the process of

A layer of sacrificial material (not shown) is then coated on the first sacrificial layer 103 by a suitable process such as a coating process or a vapor deposition process, the thickness of the sacrificial material layer being formed thereafter. The protrusion height of the bottom electrode protrusion is determined, and the material of the sacrificial material layer is amorphous carbon, photoresist, dielectric material (e.g., silicon nitride, silicon oxycarbide, porous material, etc.), or semiconductor material ( For example, at least one selected from polycrystalline silicon, amorphous silicon, germanium, etc.), and then patterning the sacrificial material layer by a lithography process or a combination process of photoetching and etching, The line width, size, shape and position of the first sacrificial protrusion 103' determine the line width, size, shape and position of the subsequently formed bottom electrode protrusion. be decided. In this embodiment, the longitudinal section along XX' in FIG. 2A of the first sacrificial protrusion 103' is a trapezoid that widens from top to bottom. The angles φ1, φ2 between the top surface of the layer 103 are less than 45 degrees, thereby contributing to the subsequent deposition of the bottom electrode material layer and the subsequently formed bottom electrode layer in the groove 102′ region. Further improve thickness uniformity. In another embodiment of the present invention, the cross-sectional shape of the first sacrificial protrusion 103' may be a spherical crown that widens further from top to bottom, i.e., the longitudinal section along line XX' in FIG. Both are inverted U-shaped. The horizontal distance between said first sacrificial protrusion 103' and said active active area 102A is preferably the minimum distance allowed for the etching alignment process of said first sacrificial protrusion 103', and said first sacrificial protrusion 103' The line width of the sacrificial protrusion 103' is the minimum line width allowed for the corresponding process.

In other embodiments of the present invention, the first sacrificial protrusion 103' and the first sacrificial layer 103 may be formed in the same process, for example, on the trench 102' and the etching protection layer 101 first, the thickness by covering the first sacrificial layer 103 with a depth equal to or greater than the sum of the depth of the groove 102' and the thickness of the first sacrificial protrusion 103', and then patterning the first sacrificial layer 10 by an etching process, A first sacrificial layer 103 is formed to fill only the groove 102', a part of the first sacrificial layer 103 has a first sacrificial protrusion 103', and the bottom surface of the first sacrificial protrusion 103' is The top surface of the etching protection layer 101 may be flush with the top surface of the etching protection layer 101 , and the top surface of the remaining portion of the first sacrificial layer 103 may be flush with the top surface of the etching protection layer 101 .

1A, 1B and 4D, in step S2, first, according to the material of the pre-formed bottom electrode, an appropriate method is selected to form the etching protection layer 101, the first sacrificial layer 103 and the first sacrificial layer 103. A bottom electrode material layer (not shown) may be coated on the surface of the sacrificial protrusion 103' of the bottom electrode material layer, for example, by a physical vapor deposition such as magnetron sputtering, evaporation, or a chemical vapor deposition method. and then forming a photoresist layer (not shown) in which a bottom electrode pattern is defined on the bottom electrode material layer by a lithography process, and etching the bottom electrode material layer using the photoresist layer as a mask. to form a bottom electrode layer (ie, the remaining bottom electrode material layer) 104, after which the photoresist layer is removed. The bottom electrode material layer can use any suitable conductive or semiconductor material known in the art, and the conductive material can be a metallic material having electrical conductivity, such as aluminum ( Al), copper (Cu), platinum (Pt), gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), rhenium (Re), palladium (Pd), rhodium ( Rh) and ruthenium (Ru), and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, or the like. In this embodiment, the bottom electrode layer (remaining bottom electrode material layer) 104 is covered by the bottom electrode resonator 1042 covered by the subsequently formed effective active area 102A and the first sacrificial protrusion 103'. a bottom electrode protrusion 1041, and extending from one side of the bottom electrode protrusion 1041 through the surface of the first sacrificial layer 103 onto a portion of the etching protection layer 101 outside the groove 102'; It includes a bottom electrode bridge portion 1040 and a bottom electrode outer periphery 1043 that is separated from both the bottom electrode resonant portion 1042 and the bottom electrode protrusion 1041, and the bottom electrode outer periphery 1043 is the bulk of the region to be formed. As one metal contact of the acoustic wave resonator, it may be connected to the side of the bottom electrode projecting portion 1041 facing away from the bottom electrode resonator portion 1042, or may be a part of the bottom electrode bridge portion of the adjacent bulk acoustic wave resonator. As such, the bottom electrode bridge portion 1040 may be separated, and in other embodiments of the invention, the bottom electrode perimeter portion 1043 may be omitted. The top surface shape of the bottom electrode resonance part 1042 may be a pentagon, or in another embodiment of the present invention, may be a square or a hexagon. The bottom electrode projecting portion 1041 is provided along at least one side of the bottom electrode resonance portion 1042 and connected to the corresponding side of the bottom electrode resonance portion 1042 . The bottom electrode bridge portion 1040 is electrically connected to at least one side or at least one corner of the bottom electrode projection portion 1041 opposite to the bottom electrode resonance portion 1042, From the corresponding side of 1041, after passing through the top surface of the first sacrificial layer 103 coated on the outside of the bottom electrode projecting portion 1041, the top surface of a portion of the etching protection layer 101 on the outer periphery of the groove 102'. That is, the bottom electrode projecting portion 1041 is provided along the side of the bottom electrode resonant portion 1042, and the bottom electrode bridge portion 1040 and the bottom electrode resonant portion 1042 are aligned. For example, the bottom electrode protruding portion 1041 may surround the entire periphery of the bottom electrode resonance portion 1042 to form a closed ring structure (see FIG. 2C), and the bottom electrode resonance It may be provided along only one side of the portion 1042, or may be an open ring structure provided along two or more continuous sides of the bottom electrode resonance portion 1042 (FIGS. 2A-2B). , 2D). The shape, line width and horizontal distance between the bottom electrode protrusion 1041 and the effective operating area 102A are all determined by the forming process of the first sacrificial protrusion 103'. Preferably, as shown in FIG. 2D, the bottom electrode bridge portion 1040 completely covers the cavity 102 above the portion of the cavity in which it is located, and across the width of the top electrode bridge portion 1080: The lack of overlap with the top electrode bridge portion 1080 improves support for subsequent membrane layers, and the overlap with the top electrode bridge portion 1080 minimizes the introduction of unnecessary parasitic parameters, e.g. When the top surface shape of the groove 102' is rectangular, the bottom electrode bridge portion 1040 extends to three sides of the rectangle. The bottom electrode resonator 1042 may be used as an input or output electrode for receiving or providing electrical signals, such as radio frequency (RF) signals. In this embodiment, the bottom electrode protruding portion 1041, the bottom electrode resonance portion 1042, and the bottom electrode bridge portion 1040 have substantially the same thickness.

1A, 1B and 4E, in step S3, first, piezoelectric material layer 105 is deposited by any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition. Alternatively, a photoresist layer (not shown) having a piezoelectric thin film pattern defined thereon is formed on the piezoelectric material layer 105 by a lithography process, and the photoresist layer is used as a mask to form the piezoelectric material layer 105. is etched to form the piezoelectric resonance layer 1051, after which the photoresist layer is removed. Materials of the piezoelectric material layer 105 are aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO ₃ ), quartz, and potassium niobate (KNbO ₃ ). Alternatively, piezoelectric materials having a wurtzite crystal structure, such as lithium tantalate (LiTaO ₃ ), and combinations thereof may be used. The piezoelectric material layer 105 includes aluminum nitride (AlN) and may also include rare earth metals, such as at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). Seeds. In addition, the piezoelectric material layer 105 contains aluminum nitride (AlN) and transition metal (eg, at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf)). may include After patterning, the remaining piezoelectric material layer 105 includes a piezoelectric resonant layer 1051 and a piezoelectric peripheral portion 1050 that are separated from each other, the piezoelectric resonant layer 1051 is located on the bottom electrode resonant portion 1042 and the bottom electrode protruding portion 1041 is exposed and may be completely or partially covered by the bottom electrode resonator 1042 . The shape of the piezoelectric resonance layer 1051 may be the same as or different from the shape of the bottom electrode resonance portion 1042, and the shape of the upper surface thereof may be a pentagon, a quadrangle, a hexagon, a heptagon, or Other polygons such as octagons are also possible. By forming a gap between the piezoelectric peripheral portion 1050 and the piezoelectric resonance layer 1051, the first sacrificial layer 103 around the bottom electrode projecting portion 1041 and the bottom electrode resonance portion 1042 is exposed. , limits the formation area of a subsequent second sacrificial layer and also provides a flat process surface for subsequent formation of a second second sacrificial protrusion, and the piezoelectric outer perimeter 1050 is formed on a subsequently formed apex. Provides separation between the electrode perimeter and the previously formed bottom electrode perimeter 1043 and also provides a flat process surface for the subsequent formation of the second sacrificial layer and the top electrode layer. be able to.

1A, 1B and 4F, in step S4, first, the piezoelectric outer peripheral portion 1050, the piezoelectric resonant layer 1051, and the piezoelectric outer peripheral portion 1050 and the piezoelectric resonant layer are subjected to a suitable process such as a coating process or a vapor deposition process. 1051 may be coated with a second sacrificial layer 106, and the second sacrificial layer 106 can fill the gap between the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer 1051, The material of the second sacrificial layer 106 can be amorphous carbon, photoresist, dielectric material (e.g. silicon nitride, silicon oxycarbide, porous material, etc.), or semiconductor material (e.g. polycrystalline silicon, amorphous silicon, germanium ), etc. Then, the second sacrificial layer 106 is formed into the piezoelectric outer peripheral portion 1050 by planarizing the top of the second sacrificial layer 106 by a CMP process. Only the gap between the piezoelectric resonance layer 1051 is filled, and the piezoelectric outer peripheral portion 1050, the piezoelectric resonance layer 1051 and the second sacrificial layer 106 form a flat upper surface. In another embodiment of the present invention, the second sacrificial layer 106 on the top surface of the piezoelectric outer periphery 1050 and the piezoelectric resonant layer 1051 is removed by an etch back process, thereby removing the piezoelectric outer periphery 1050 and the piezoelectric resonant layer 1051 . Only the interstices may be filled. Next, a sacrificial material (not shown) is coated on the piezoelectric outer periphery 1050, the piezoelectric resonant layer 1051 and the second sacrificial layer 106 by a suitable process such as a coating process or a vapor deposition process, and the thickness of the sacrificial material is The height is determined by the protrusion height of the second sacrificial protrusion 107 to be formed and may be equal to the protrusion height of the first sacrificial protrusion 103' in FIG. 4C, the sacrificial material being amorphous carbon, photo at least one selected from resists, dielectric materials (e.g., silicon nitride, silicon oxycarbide, porous materials, etc.), or semiconductor materials (e.g., polycrystalline silicon, amorphous silicon, germanium), etc. may be the same as the material of the second sacrificial layer 106, which saves cost and simplifies the process; A second sacrificial protrusion 107 is formed by patterning, and the shape, size and position of the top electrode protrusion to be formed later are determined by the shape, size and position of the second sacrificial protrusion 107 . Preferably, the sidewalls of the second sacrificial protrusions 107 are sloped sidewalls with respect to the plane in which the piezoelectric resonance layer 1051 is located, and the sidewalls of the second sacrificial protrusions 107 and the top surface of the piezoelectric resonance layer 1051 are between the sidewalls of the second sacrificial protrusions 107 . are both 45 degrees or less, which contributes to covering the top electrode recessed portion 1081 with material after this, avoids cutting, and contributes to improving thickness uniformity. do. More preferably, the line width of the second sacrificial protrusion 107 is the minimum line width allowed for the corresponding process, and the horizontal distance between the second sacrificial protrusion 107 and the piezoelectric resonance layer 1051 is the corresponding It is the minimum distance allowed for the process, which achieves a favorable shear wave blocking effect and contributes to a reduction in device size. In one embodiment of the present invention, the second sacrificial protrusion 107 and the first sacrificial protrusion 103' may be centrosymmetric with respect to the piezoelectric resonant layer 1051, and the subsequently formed top electrode protrusion 1081 and The previously formed bottom electrode protrusion 1041 is centrosymmetric, which allows the same transverse wave blocking effect on both sides of the subsequently formed cavity resonance region, improving the performance of the device.

In other embodiments of the present invention, the second sacrificial protrusion 107 and the second sacrificial layer 106 may be formed by the same process, for example, first piezoelectric outer periphery 1050, piezoelectric resonance layer 1051 and piezoelectric outer periphery 1050 are formed. and the piezoelectric resonance layer 1051, a second sacrificial layer 106 having a thickness equal to or greater than the sum of the thickness of the piezoelectric resonance layer 1051 and the thickness of the second sacrificial protrusion 107 is coated, and then the second sacrificial layer 106 is formed by an etching process. By patterning the second sacrificial layer 106, the second sacrificial layer 106 filled only in the gap between the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer 1051 is formed. A second sacrificial protrusion 107 may be provided, and the bottom surface of the second sacrificial protrusion 107 and the top surface of the piezoelectric resonance layer 1051 may be flush with each other. The top surface and the top surface of the piezoelectric resonance layer 1051 may be flush with each other.

1A, 1B and 4G, in step S5, first, based on the material of the pre-formed top electrode, select an appropriate method, and A top electrode material layer (not shown) may be coated on the surfaces of the sacrificial layer 106 and the second sacrificial protrusion 107, for example by physical vapor deposition, such as magnetron sputtering deposition, or by chemical vapor deposition methods. A top electrode material layer may be formed, the top electrode material layer may be uniform in thickness at each location, and then a photoresist layer (not shown) in which the top electrode pattern is defined is lithographically deposited. The top electrode layer (i.e., the patterned top electrode material layer or the remaining top electrode material layer) is formed on the top electrode material layer in the process and etched using the photoresist layer as a mask. layer) 108, after which the photoresist layer is removed. The top electrode material layer may use any suitable conductive or semiconducting material known in the art, and the conductive material may be a metallic material having electrical conductivity, such as Al, Cu, Pt, Au, Mo, W, Ir, Os, Re, Pd, Rh and Ru, etc., and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, etc. is. In this embodiment, the top electrode layer 108 includes a top electrode resonance portion 1082 coated on the piezoelectric resonance layer 1051, a top electrode protrusion portion 1081 coated on the second sacrificial protrusion 107, and a top electrode protrusion portion 1081. , through the top surface of a portion of the second sacrificial layer 106 and onto the piezoelectric outer peripheral portion 1050 outside the top electrode projecting portion 1081 , and the top electrode resonance portion 1082 . and a top electrode protrusion 1081 and a top electrode perimeter 1083 that are both separated, and the top electrode perimeter 1083 serves as one metal contact for the bulk acoustic wave resonator to be formed in the region. It may be connected to one side of the electrode bridge portion 1080 facing away from the top electrode protrusion portion 1081, or may be separated from the top electrode bridge portion 1080 as part of the top electrode bridge portion of the adjacent bulk acoustic wave resonator. Well, in other embodiments of the invention, the top electrode perimeter 1083 may be omitted. The shape of the top surface of the top electrode resonance part 1082 may be the same as or different from the shape of the piezoelectric resonance layer 1051. The shape of the top surface is, for example, a pentagon. The area of the top electrode resonator 1082 is preferably larger than the piezoelectric resonator layer 1051 so as to be completely sandwiched between the electrode resonator 1042, thereby contributing to the reduction of device size and parasitic parameters. In other embodiments of the present invention, the shape of the top electrode resonator 1082 may also be polygonal, such as square, hexagon, heptagon, or octagon. The top electrode layer 108 may be used as an input electrode for receiving or providing electrical signals, such as radio frequency (RF) signals, or as an output electrode. For example, when bottom electrode layer 104 is used as an input electrode, top electrode layer 108 may be used as an output electrode, and when bottom electrode layer 104 is used as an output electrode, top electrode layer 108 may be used as an input electrode. The piezoelectric resonance layer 1051 converts an electrical signal input via the top electrode resonance section 1082 or the bottom electrode resonance section 1042 into a bulk acoustic wave. For example, the piezoelectric resonant layer 1051 converts electrical signals into bulk acoustic waves by physical vibration. The top electrode projecting portion 1081 is provided along at least one side of the top electrode resonant portion 1082 and connected to the corresponding side of the top electrode resonant portion 1082. It is provided along the side of the top electrode resonant portion 1082 and is provided at least in a region where the top electrode bridge portion 1080 and the top electrode resonant portion 1082 are aligned. A closed ring structure is formed around the entire circumference of the electrode resonant portion 1082 (shown in FIGS. 2C and 2D), and for example, the top electrode protrusion 1081 extends at a plurality of continuous sides of the top electrode resonant portion 1082. This constitutes an open ring structure (shown in Figures 2A and 2B). The top electrode bridge portion 1080 is electrically connected to the side of the top electrode protruding portion 1081 facing away from the top electrode resonant portion 1082. From above the top electrode protruding portion 1081, a part of the second sacrificial layer 106 to the top surface of a portion of the etching protection layer 101 outside the groove 102', and the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 are connected to each other. At least one side of the trench 102' is exposed from each of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 when offset (ie, they do not overlap in the cavity region). In one embodiment of the present invention, referring to FIGS. 2A and 2B, the top electrode protrusion 1081 faces the bottom electrode protrusion 1041 of the bottom electrode bridge 1040 in a direction perpendicular to the bottom surface of the groove 102'. , and the bottom electrode projecting portion 1041 does not overlap the side of the top electrode bridge portion 1080 facing the top electrode projecting portion 1081 . The projections of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 on the bottom surface of the groove 102' are just connected or separated from each other, and the top electrode bridge portion 1080 is connected to the groove 102. ' may extend above a portion of the substrate at the perimeter of only one side of '.

Referring to FIGS. 1A, 1B and 4H, in step S6, a photo-etching and etching process or a combined process with laser ablation is applied to the edge of the piezoelectric outer periphery 1050 facing the groove 102′ or the bulk acoustic wave resonance. Perforations may be made around the periphery of the device region of the device, part of the first sacrificial protrusions 103', part of the first sacrificial layer 103 other than the first sacrificial protrusions 103', and part of the second sacrificial layer 103'. An open hole (not shown) is formed that can expose at least one of the sacrificial protrusion 107 or the second sacrificial layer 106 other than the second sacrificial protrusion 107, and then gas and/or gas is injected into the open hole. removing the second sacrificial protrusion 107, the first sacrificial protrusion 103', the second sacrificial layer 106, and the first sacrificial layer 103 by introducing a chemical solution, and emptying the trench again; to form a cavity 102, the cavity 102 includes a space of the groove 102' increased by the bottom electrode protrusion 1041, a space increased by the top electrode protrusion 1081, and below the top electrode protrusion 1081, and the space originally occupied by the second sacrificial layer 106 . The bottom electrode resonance part 1042, the piezoelectric resonance layer 1051, and the top electrode resonance part 1082, which float above the cavity 102 and are stacked in order, constitute an independent bulk acoustic thin film. The portion where the top electrode resonator 1082 and the cavity 102 overlap each other along the vertical direction is the effective area, defined as the effective actuation area 102A, which allows electrical energy, such as radio frequency signals, to pass through the bottom electrode. When the voltage is applied to the resonance section 1042 and the top electrode resonance section 1082 , due to the piezoelectric phenomenon occurring in the piezoelectric resonance layer 1051 , vibration and resonance occur in the thickness direction (that is, the longitudinal direction) of the piezoelectric resonance layer 1051 , and the cavity 102 The other area of is the ineffective area 102B, which is an area that does not resonate due to the piezoelectric phenomenon even when electrical energy is applied to the top electrode layer 108 and the bottom electrode layer 104 . The bulk acoustic thin film floating above the effective operating area 102A and composed of the bottom electrode resonance part 1042, the piezoelectric resonance layer 1051 and the top electrode resonance part 1082, which are stacked in order, corresponds to the vibration of the piezoelectric phenomenon of the piezoelectric resonance layer 1051. can output a radio frequency signal with a resonance frequency that Specifically, when electrical energy is applied to the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042, the piezoelectric phenomenon occurring in the piezoelectric resonance layer 1051 generates bulk acoustic waves. In this case, the generated bulk acoustic waves are not only the desired longitudinal waves, but also parasitic transverse waves, which are interrupted by the top electrode protrusion 1081 and the bottom electrode protrusion 1041, are confined to the effective operating area 102A, and the outer periphery of the cavity. , thereby improving the acoustic wave loss due to the transverse wave propagating to the film layers at the outer periphery of the cavity, thereby improving the quality factor of the resonator, and finally Device performance can be improved.

It should be noted that step S6 may be performed after all membrane layers above the cavity 102 to be formed have been fabricated, thereby subsequently forming the first sacrificial layer 103 and the second sacrificial layer 106. can be used to protect the space where the cavity is located and the film layer structure stacked with the bottom electrode layer 104 to the top electrode layer 108 formed thereon, and after the cavity 102 is formed, subsequent subsequent To avoid the risk of cavity collapse caused when performing the process. Also, the open hole formed in step S6 may be left so that subsequent packaging processes such as bonding two substrates can seal the open hole and also seal the cavity 102 .

In step S1 of the method for manufacturing the bulk acoustic wave resonator of each of the above embodiments, the first sacrificial layer 103 is partially removed by etching the substrate to form the groove 102' and filling the groove 102'. , the cavity 102 formed in step S6 has a groove structure whose entire bottom is recessed into the substrate, but the technical solution of the present invention is not limited to this. In step S1 of another embodiment of the present invention, by further forming a first sacrificial layer 103 protruding entirely above the substrate by a combined process of film layer deposition and photo-etching and etching, step S6 2E and 5, in step S1, a groove 102 for forming the cavity 102 is formed in a cavity structure projecting from the substrate surface. ' is first coated on the etching protection layer 101 on the surface of the base 100 with a first sacrificial layer 103, and then by a combined photoetching and etching process, the first sacrificial layer 103 is formed. is patterned to leave only the first sacrificial layer 103 covering the region corresponding to the cavity 102, and further the first sacrificial layer 103 is formed on a part of the substrate, the first sacrificial layer 103 is To fabricate the first sacrificial protrusions 103' after the thickness of the first sacrificial layer 103 determines the depth of the subsequently formed cavities 102, which may be a structure that widens from top to bottom. is coated on the first sacrificial layer 103 and the substrate, and then the first sacrificial protrusions 103' are formed on a portion of the first sacrificial layer 103 by a combination process of photoetching and etching. In this embodiment, the corresponding sidewalls of the bottom electrode perimeter 1043, the bottom electrode bridge 1040, the piezoelectric perimeter 1050, the top electrode perimeter 1083, and the top electrode bridge 1080 to be formed are the protruding first sacrificial layers. 103, and the vertical cross-section must all be a "Z"-shaped structure, and the subsequent steps are the manufacturing method of the bulk acoustic wave resonator of the embodiment shown in FIGS. 4A-4H. are exactly the same as their counterparts in , and will not be described in detail here.

Preferably, in the bulk acoustic wave resonator of the present invention, the bottom electrode bridge portion, the bottom electrode projection portion, and the bottom electrode resonator portion are manufactured in the same process by using the manufacturing method of the bulk acoustic wave resonator of the present invention, The top electrode bridge portion, the top electrode projection portion and the top electrode resonance portion are manufactured by the same process, further simplifying the process and reducing the manufacturing cost.

Of course, those skilled in the art can make various changes and modifications to this invention without departing from the spirit and scope of this invention. Thus, it is intended that the present invention include these modifications and variations of the present invention as they fall within the scope of the claims of the present invention and their equivalents.

100 base 101 etch protection layer 102 cavity 102' groove 102A active active area 102B ineffective area 103 first sacrificial layer 103' first sacrificial protrusion 104 bottom electrode layer (i.e. remaining bottom electrode material layer)
1040 bottom electrode bridge portion 1041 bottom electrode protruding portion 1042 bottom electrode resonance portion 1043 bottom electrode outer peripheral portion 105 piezoelectric material layer 1050 piezoelectric outer peripheral portion 1051 piezoelectric resonance layer (or referred to as piezoelectric resonance portion)
106 second sacrificial layer 107 second sacrificial protrusion 108 top electrode layer (i.e. remaining top electrode material layer)
1080 top electrode bridge portion 1081 top electrode protrusion portion 1082 top electrode resonance portion 1083 top electrode outer peripheral portion

Claims (21)

A bulk acoustic wave resonator,
a substrate;
A bottom electrode layer provided on the substrate, wherein a cavity is formed between the bottom electrode layer and the substrate, the bottom electrode layer being located in the region of the cavity and away from the bottom surface of the cavity. a bottom electrode layer having bottom electrode projections projecting in a direction;
a piezoelectric resonance layer formed on the bottom electrode layer above the cavity;
a top electrode layer formed on the piezoelectric resonance layer, the top electrode layer having a top electrode projecting portion located in the region of the cavity and projecting away from the bottom surface of the cavity; Both the top electrode protrusion and the bottom electrode protrusion are located in the region of the cavity on the outer circumference of the piezoelectric resonance layer, and both the bottom electrode protrusion and the top electrode protrusion surround the piezoelectric resonance layer. a top electrode layer extending in a direction and facing each other at least partially;
the bottom electrode layer further includes a bottom electrode bridge portion having one end connected to the bottom electrode protrusion and the other end abutting on the substrate at the outer periphery of the cavity;
the top electrode layer further includes a top electrode bridge portion having one end connected to the top electrode protrusion and the other end extending above the substrate at the outer periphery of the cavity;
the bottom electrode bridge portion and the top electrode bridge portion are displaced from each other,
the bottom electrode bridge completely covers the cavity above the portion of the cavity in which it is located and does not overlap the top electrode bridge in the width direction of the top electrode bridge;
A bulk acoustic wave resonator characterized by: the bottom electrode layer further includes a bottom electrode resonance portion overlapping the piezoelectric resonance layer;
the top electrode layer further includes a top electrode resonance part overlapping the piezoelectric resonance layer;
2. The bulk acoustic wave resonator according to claim 1 , wherein both said bottom electrode resonator and said top electrode resonator are polygonal. the bottom electrode projecting portion is provided along a side of the bottom electrode resonant portion and is provided at least in a region where the bottom electrode bridge portion and the bottom electrode resonant portion are aligned;
The top electrode projecting portion is provided along a side of the top electrode resonant portion and is provided at least in a region where the top electrode bridge portion and the top electrode resonant portion are aligned. Item 3. The bulk acoustic wave resonator according to item 2. the bottom electrode protrusion is offset from at least the top electrode bridge above the cavity, or the bottom electrode protrusion surrounds the entire circumference of the bottom electrode resonance section;
The top electrode protrusion is displaced from at least the bottom electrode bridge above the cavity, or the top electrode protrusion surrounds the top electrode resonance section. 4. The bulk acoustic wave resonator according to claim 3 . 5. Bulk acoustic wave resonance according to claim 4 , characterized in that the projections of the top electrode protrusion and the bottom electrode protrusion on the bottom surface of the cavity just connect or are mutually offset or overlap. vessel. the bottom electrode projecting portion, the bottom electrode bridge portion, and the bottom electrode resonance portion are formed of the same film layer,
3. The bulk acoustic wave resonator according to claim 2 , wherein said top electrode protrusion, said top electrode bridge and said top electrode resonator are formed of the same film layer. A bulk acoustic wave resonator,
a substrate;
A bottom electrode layer provided on the substrate, wherein a cavity is formed between the bottom electrode layer and the substrate, the bottom electrode layer being located in the region of the cavity and away from the bottom surface of the cavity. a bottom electrode layer having bottom electrode projections projecting in a direction;
a piezoelectric resonance layer formed on the bottom electrode layer above the cavity;
a top electrode layer formed on the piezoelectric resonance layer, the top electrode layer having a top electrode projecting portion located in the region of the cavity and projecting away from the bottom surface of the cavity; Both the top electrode protrusion and the bottom electrode protrusion are located in the region of the cavity on the outer circumference of the piezoelectric resonance layer, and both the bottom electrode protrusion and the top electrode protrusion surround the piezoelectric resonance layer. a top electrode layer extending in a direction and facing each other at least partially;
the horizontal distance between the bottom electrode protrusion and the piezoelectric resonance layer is the minimum distance allowed in the process of manufacturing the bottom electrode protrusion;
A bulk acoustic wave resonator according to claim 1, wherein a horizontal distance between said top electrode protrusion and said piezoelectric resonance layer is a minimum distance allowed in a process of manufacturing said top electrode protrusion. sidewalls of the top electrode projecting portion are inclined with respect to the top surface of the piezoelectric resonance layer;
7. The bulk acoustic wave resonator according to claim 1 , wherein side walls of said bottom electrode projecting portion are inclined with respect to the bottom surface of said piezoelectric resonance layer. an angle between the side wall of the top electrode protrusion and the top surface of the piezoelectric resonance layer is 45 degrees or less;
9. The bulk acoustic wave resonator according to claim 8 , wherein the angle between the side wall of said bottom electrode protrusion and the bottom surface of said piezoelectric resonance layer is 45 degrees or less. the line width of the bottom electrode protrusion is the minimum line width allowed in the process of manufacturing the bottom electrode protrusion;
10. The line width of the top electrode protrusion is the minimum line width allowed in the process of manufacturing the top electrode protrusion . bulk acoustic wave resonator. 10. The cavity according to any one of claims 1 to 6 or 9 , wherein the cavity has a groove structure in which the entire bottom is recessed in the substrate, or a cavity structure in which the entire protrusion is provided on the surface of the substrate. 1. The bulk acoustic wave resonator according to 1. A filter comprising at least one bulk acoustic wave resonator according to any one of claims 1-11. A radio frequency communication system comprising at least one filter according to claim 12. A method of manufacturing a bulk acoustic wave resonator, comprising:
providing a substrate and forming a first sacrificial layer having a first sacrificial protrusion on a portion of the substrate;
forming a bottom electrode layer on the first sacrificial layer and forming portions of the bottom electrode layer covering surfaces of the first sacrificial protrusions as bottom electrode protrusions;
forming a piezoelectric resonance layer on the bottom electrode layer exposing the bottom electrode protrusion;
forming a second sacrificial layer having a second sacrificial protrusion in an exposed area around the piezoelectric resonant layer;
forming a top electrode layer on the piezoelectric resonance layer and a portion of the second sacrificial layer around the piezoelectric resonance layer, and forming a portion of the top electrode layer covering the second sacrificial protrusion as a top electrode protrusion; forming as
removing the second sacrificial layer having the second sacrificial protrusion and the first sacrificial layer having the first sacrificial protrusion; removing the second sacrificial layer having the second sacrificial protrusion and the first sacrificial layer; forming a cavity at the location of the first sacrificial layer having one sacrificial protrusion, wherein the top electrode protrusion and the bottom electrode protrusion are both in the region of the cavity at the perimeter of the piezoelectric resonant layer. wherein the bottom electrode protrusion and the top electrode protrusion both extend in a peripheral direction surrounding the piezoelectric resonance layer and are at least partially opposed to each other. A method for manufacturing a bulk acoustic wave resonator. Forming the first sacrificial layer with the first sacrificial protrusions on a portion of the substrate comprises forming grooves in the substrate by etching the substrate; forming a layer to fill the trench; coating a layer of sacrificial material over the first sacrificial layer and the substrate; forming the first sacrificial layer to protrude, or
Forming the first sacrificial layer with the first sacrificial protrusions on a portion of the substrate comprises: coating the first sacrificial layer on the substrate; and patterning the first sacrificial layer. forming the first sacrificial layer to protrude from a portion of the substrate; coating the first sacrificial layer and the substrate with the sacrificial material layer; and forming the first sacrificial protrusions by patterning so as to protrude from a portion of the first sacrificial layer. The method of making the vessel. removing the second sacrificial layer having the second sacrificial protrusions and the first sacrificial layer having the first sacrificial protrusions, comprising:
After forming the top electrode layer, at least part of the first sacrificial protrusions, part of the second sacrificial protrusions, part of the first sacrificial layer other than the first sacrificial protrusions, or the second sacrificial protrusions forming at least one open hole exposing a portion of the second sacrificial layer other than two sacrificial protrusions;
removing the second sacrificial layer having the second sacrificial protrusions and the first sacrificial layer having the first sacrificial protrusions by introducing a gas and/or a chemical solution into the open holes; 15. The method of manufacturing a bulk acoustic wave resonator according to claim 14 , comprising: forming the bottom electrode layer comprises depositing a bottom electrode material layer overlying the first sacrificial layer having the first sacrificial protrusions; and patterning the bottom electrode material layer, forming a bottom electrode bridge portion, the bottom electrode protrusion, and a bottom electrode resonance portion which are connected in order, wherein the bottom electrode resonance portion and the piezoelectric resonance layer overlap and face the bottom electrode protrusion; and a step of abutting one end of the bottom electrode bridge portion on the substrate at the outer periphery of the cavity. Production method. forming the top electrode layer includes depositing a top electrode material layer overlying the second sacrificial layer having the second sacrificial protrusions and the piezoelectric resonance layer; a step of forming a top electrode bridge portion, the top electrode protrusion portion, and a top electrode resonance portion which are connected in order by patterning, wherein the top electrode resonance portion and the piezoelectric resonance layer are overlapped to form the top electrode protrusion; one end of the top electrode bridge portion facing away from the portion extends above the substrate at the outer periphery of the cavity, and the top electrode bridge portion and the bottom electrode bridge portion are offset from each other. 8. The method of manufacturing a bulk acoustic wave resonator according to claim 17 , characterized by: Both the bottom electrode resonance portion and the top electrode resonance portion are polygonal,
the bottom electrode projecting portion is provided along a side of the bottom electrode resonant portion and is provided at least in a region where the bottom electrode bridge portion and the bottom electrode resonant portion are aligned;
The top electrode projecting portion is provided along a side of the top electrode resonant portion and is provided at least in a region where the top electrode bridge portion and the top electrode resonant portion are aligned. Item 19. A method for manufacturing a bulk acoustic wave resonator according to Item 18 . the horizontal distance between the bottom electrode protrusion and the piezoelectric resonance layer is the minimum distance allowed in the process of manufacturing the bottom electrode protrusion;
14 to 16 and claims, wherein the horizontal distance between the top electrode protrusion and the piezoelectric resonance layer is the minimum distance allowed in the process of manufacturing the top electrode protrusion. 20. A method for manufacturing a bulk acoustic wave resonator according to any one of items 18 to 19 . the line width of the bottom electrode protrusion is the minimum line width allowed in the process of manufacturing the bottom electrode protrusion;
Any one of claims 14 to 16 and claims 18 to 19 , wherein the line width of the top electrode protrusion is a minimum line width allowed in a process for manufacturing the top electrode protrusion. 2. A method for manufacturing a bulk acoustic wave resonator according to item 1.

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