CN112039486A

CN112039486A - Film bulk acoustic resonator and method for manufacturing the same

Info

Publication number: CN112039486A
Application number: CN202010549498.2A
Authority: CN
Inventors: 黄河
Original assignee: Smic Ningbo Co ltd Shanghai Branch
Current assignee: Smic Ningbo Co ltd Shanghai Branch; Ningbo Semiconductor International Corp Shanghai Branch
Priority date: 2020-06-16
Filing date: 2020-06-16
Publication date: 2020-12-04

Abstract

The present invention relates to a film bulk acoustic resonator and a method for manufacturing the same, wherein the film bulk acoustic resonator comprises: a first substrate provided with a first cavity; the piezoelectric laminated structure comprises a first electrode, a piezoelectric layer and a second electrode which are sequentially laminated from bottom to top, the piezoelectric layer covers a first cavity, the edges of the first electrode and the second electrode are all positioned within the boundary of an area enclosed by the first cavity, and an effective resonance area comprises the area where the first electrode, the piezoelectric layer and the second electrode are mutually overlapped in the direction vertical to the surface of the piezoelectric layer; the first electrode leading-out structure is connected with the edge of the first electrode and extends to the invalid resonance area to be used as a first signal connecting end, and a first gap is formed by the edge of the valid resonance area and the piezoelectric laminated structure in a surrounding mode; and the second electrode leading-out structure is connected with the edge of the second electrode and extends to the invalid resonance area to be used as a second signal connecting end, and a second gap is formed by the edge of the valid resonance area and the piezoelectric laminated structure. The invention improves the Q value by eliminating the boundary clutter of the effective resonance area.

Description

Film bulk acoustic resonator and method for manufacturing the same

Technical Field

The invention relates to the field of semiconductor device manufacturing, in particular to a film bulk acoustic resonator and a manufacturing method thereof.

Background

Since the development of analog rf communication technology in the early 90 th century, rf front-end modules have gradually become the core components of communication devices. In all rf front-end modules, the filter has become the most fierce component to grow and have the greatest development prospect. With the rapid development of wireless communication technology, 5G communication protocols are becoming mature, and the market also puts forward more strict standards on various aspects of the performance of radio frequency filters. The performance of the filter is determined by the resonator elements that make up the filter. Among the existing filters, the Film Bulk Acoustic Resonator (FBAR) is one of the most suitable filters for 5G applications due to its small size, low insertion loss, large out-of-band rejection, high quality factor, high operating frequency, large power capacity, and good anti-electrostatic shock capability.

Generally, a film bulk acoustic resonator includes two film electrodes, and a piezoelectric film layer is disposed between the two film electrodes, and the working principle of the film bulk acoustic resonator is to utilize the piezoelectric film layer to generate vibration under an alternating electric field, the vibration excites a bulk acoustic wave propagating along the thickness direction of the piezoelectric film layer, the acoustic wave is transmitted to an interface between an upper electrode and a lower electrode and an air interface to be reflected back, and then reflected back and forth inside the film to form oscillation. When the sound wave is transmitted in the piezoelectric film layer and is just odd times of half wavelength, standing wave oscillation is formed.

However, the quality factor (Q) of the currently manufactured cavity type film bulk acoustic resonator cannot be further improved, and thus the requirement of a high-performance radio frequency system cannot be met.

Disclosure of Invention

The invention aims to provide a film bulk acoustic resonator and a manufacturing method thereof, which can improve the quality factor of the film bulk acoustic resonator and further improve the device performance.

In order to achieve the above object, the present invention provides a thin film bulk acoustic resonator comprising:

a first substrate having a first cavity therein;

the piezoelectric laminated structure comprises a first electrode, a piezoelectric layer and a second electrode which are sequentially laminated from bottom to top, the edges of the first electrode and the second electrode are all positioned within the boundary of an area enclosed by the first cavity, and an effective resonance area comprises the area where the first electrode, the piezoelectric layer and the second electrode are mutually overlapped in the direction vertical to the surface of the piezoelectric layer;

the first electrode leading-out structure is connected with the edge of the first electrode and extends to the invalid resonance area to be used as a first signal connecting end, and a first gap is formed by the edge of the valid resonance area and the piezoelectric laminated structure in an enclosing mode;

and the second electrode leading-out structure is connected with the edge of the second electrode and extends to the invalid resonance area to be used as a second signal connecting end, and a second gap is formed by the edge of the valid resonance area and the piezoelectric laminated structure in an enclosing manner.

The invention also provides a manufacturing method of the film bulk acoustic resonator, which comprises the following steps:

providing a temporary substrate;

sequentially forming a second electrode layer, a piezoelectric layer and a first electrode on the temporary substrate, wherein the first electrode is positioned in an effective resonance area;

forming a first electrode leading-out structure, wherein the first electrode leading-out structure is connected with the edge of the first electrode and extends to an invalid resonance area to serve as a first signal connecting end, and a first gap is formed by the boundary of the valid resonance area, the piezoelectric layer and the first electrode;

forming a first sacrificial layer covering the first electrode and the first electrode leading-out structure positioned at the boundary of the effective resonance area;

forming the first substrate, covering the first sacrificial layer and the piezoelectric layer;

removing the temporary substrate;

patterning the second electrode layer to form the second electrode; the effective resonance region includes a region where the first electrode, the piezoelectric layer, and the second electrode overlap each other in a direction perpendicular to a surface of the piezoelectric layer;

forming a second electrode leading-out structure, wherein the second electrode leading-out structure is connected with the edge of the second electrode and extends to an invalid resonance area to serve as a second signal connecting end, and a second gap is formed by the edge of the valid resonance area, the piezoelectric layer and the second electrode;

and removing the first sacrificial layer.

The film bulk acoustic resonator has the beneficial effects that:

through adopting solitary first electrode extraction structure and second electrode extraction structure respectively on first electrode side and second electrode side, first electrode extraction structure and second electrode extraction structure form first space and second space in effective resonance area boundary region respectively, and first space and second space can reach the effect of eliminating effective resonance area boundary clutter, and then promote the Q value of syntonizer.

Furthermore, the first electrode leading-out structure and the second electrode leading-out structure are made of metal materials with lower resistivity and better heat conductivity, so that the impedance can be reduced, and the heat conduction can be enhanced.

Further, the piezoelectric layer is provided with a void edge gap so that the edge of the piezoelectric layer is exposed to air, and transverse wave loss can be suppressed.

Further, when the piezoelectric layer is a complete film layer, the structural strength of the resonator can be increased; the piezoelectric layer is formed on the flat electrode layer, so that the piezoelectric layer has better lattice orientation, the piezoelectric property of the piezoelectric layer is improved, and the overall performance of the resonator is further improved.

Furthermore, a first protrusion is arranged on the surface of the first electrode and/or a second protrusion is arranged on the surface of the second electrode, and an acoustic impedance mismatch area is formed in the area where the first protrusion and the second protrusion are located, so that acoustic impedance mismatch between the boundary of the effective resonance area and the inside of the effective resonance area can be realized; the projection of the first bulge and the first overhead part on the surface of the piezoelectric layer is closed or has a gap ring shape or the projection of the second bulge and the second overhead part on the surface of the piezoelectric layer is closed or has a gap ring shape, so that the effect of inhibiting the leakage of transverse clutter can be jointly played, and the quality factor of the resonator is further improved.

Furthermore, a first dielectric layer and a second dielectric layer are respectively formed on the upper surface and the lower surface of the piezoelectric layer, so that the bonding effect can be improved when the top cover is formed subsequently, and meanwhile, the mechanical strength of the whole resonator can be improved due to the arrangement of the first dielectric layer and the second dielectric layer.

The manufacturing method of the film bulk acoustic resonator has the advantages that:

form second electrode layer and piezoelectric layer in proper order on the temporary substrate surface for the piezoelectric layer can form on smooth second electrode layer, guarantees that the piezoelectric layer has better lattice orientation, improves the piezoelectricity characteristic of piezoelectric layer, and then improves the performance of syntonizer. The first electrode and the first electrode leading-out structure are formed on the first surface of the piezoelectric layer, and then the second electrode and the second electrode leading-out structure are formed on the second surface of the piezoelectric layer, so that the process of electrode patterning is carried out on the two surfaces of the piezoelectric layer, the piezoelectric layer is prevented from being etched in the electrode forming process, the integrity and the flatness of the piezoelectric layer are ensured, the influence on the piezoelectric layer is reduced, and the performance of the resonator is improved; and the method is compatible with the resonator main body process, and the flow is simple.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic cross-sectional view of a film bulk acoustic resonator according to an embodiment of the present invention;

FIG. 1A shows a top view of FIG. 1 in the X direction;

FIG. 2 is a schematic cross-sectional view of a film bulk acoustic resonator including a first bump, a second bump, a first dielectric layer and a second dielectric layer according to an embodiment of the present invention;

FIG. 2A is a top view of FIG. 2 taken along the X direction;

FIG. 3 is a schematic cross-sectional view of a film bulk acoustic resonator including a top cover according to an embodiment of the present invention;

FIG. 4 is a schematic cross-sectional view of a film bulk acoustic resonator including an air gap, a first dielectric layer, and a second dielectric layer according to another embodiment of the present invention;

FIG. 5 is a flow chart of a method for fabricating a film bulk acoustic resonator according to an embodiment of the present invention;

fig. 6-16 are schematic structural diagrams corresponding to corresponding steps of a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present invention.

Description of reference numerals:

1. a first substrate; 11. a substrate; 12. a support layer; 121. a first cavity; 3. a piezoelectric stack structure; 31. a first electrode; 31', a first electrode layer; 32. a piezoelectric layer; 321. an air side gap; 33. a second electrode; 33', a second electrode layer; 4. a first electrode lead-out structure; 41. a first overhead portion; 42. a first lap joint portion; 43. a first void; 5. a second electrode lead-out structure; 51. a second overhead portion; 52. a second lap joint portion; 53. a second void; 6. a first protrusion; 7. a second protrusion; 8. a top cover; 81. a bonding layer; 811. a second cavity; 812. a release aperture; 82. a second substrate; 90. a temporary substrate; 91. a first sacrificial layer; 92. a first sacrificial protrusion; 93. a second sacrificial protrusion; 94. a second sacrificial layer; 95. a first dielectric layer; 96. a second dielectric layer; 97. an isolation layer.

Detailed Description

The existing manufactured cavity type film bulk acoustic resonator has the problems of transverse wave loss, insufficient structural strength, incapability of further improving quality factor (Q), low yield and the like, so that the requirement of a high-performance radio frequency system cannot be met.

In order to solve the above problems, the present invention provides a film bulk acoustic resonator, wherein a first electrode lead-out structure and a second electrode lead-out structure are separately adopted on a first electrode side and a second electrode side, the first electrode lead-out structure and the second electrode lead-out structure are respectively located on two sides of an effective resonance area to form an oblique symmetric structure, the first electrode lead-out structure and the second electrode lead-out structure respectively form a first gap and a second gap in a boundary area of the effective resonance area, and the first gap and the second gap can achieve an effect of eliminating boundary clutter of the effective resonance area, so as to improve a Q value of the resonator.

The film bulk acoustic resonator and the method for manufacturing the same according to the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and drawings, it being understood, however, that the concepts of the present invention may be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. The drawings are in simplified form and are not to scale, but are provided for convenience and clarity in describing embodiments of the invention.

The terms "first," "second," and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other sequences than described or illustrated herein. Similarly, if the method described herein comprises a series of steps, the order in which these steps are presented herein is not necessarily the only order in which these steps may be performed, and some of the described steps may be omitted and/or some other steps not described herein may be added to the method. Although elements in one drawing may be readily identified as such in other drawings, the present disclosure does not identify each element as being identical to each other in every drawing for clarity of description.

Fig. 1 is a schematic cross-sectional structure diagram of a thin film bulk acoustic resonator according to an embodiment of the present invention, and referring to fig. 1, the thin film bulk acoustic resonator includes:

a first substrate 1, wherein a first cavity 121 is arranged in the first substrate 1;

the piezoelectric laminated structure 3 comprises a first electrode 31, a piezoelectric layer 32 and a second electrode 33 which are sequentially laminated from bottom to top, the edges of the first electrode 31 and the second electrode 33 are all positioned within the boundary of the area enclosed by the first cavity 121, the effective resonance area comprises the area where the first electrode 31, the piezoelectric layer 32 and the second electrode 33 are mutually overlapped in the direction vertical to the surface of the piezoelectric layer 32, and the ineffective resonance area is an area outside the effective resonance area;

the first electrode lead-out structure 4 is connected with the edge of the first electrode 31 and extends to the invalid resonance area to be used as a first signal connection end, and a first gap 43 is formed by the edge of the valid resonance area and the piezoelectric laminated structure 3;

and the second electrode lead-out structure 5 is connected with the edge of the second electrode 33 and extends to the invalid resonance area to be used as a second signal connection end, and a second gap 53 is formed by the edge of the valid resonance area and the piezoelectric laminated structure 3.

In this embodiment, the material of the first substrate 1 may be any suitable substrate known to those skilled in the art, and may be at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III/V compound semiconductors.

In this embodiment, the first substrate 1 is a double-layer structure, and includes a base 11 and a support layer 12, the support layer 12 and the piezoelectric stack structure 3 are sequentially stacked on the base 11, and the first cavity 121 is disposed in the support layer 12. It should be noted that the support layer 12 may be bonded to the substrate 11 by means of a bonding layer or deposition. The material of the bonding layer comprises silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate. In addition, the bonding layer may also use an adhesive such as a photo-curing material or a thermosetting material, for example, a Die Attach Film (DAF) or a Dry Film (Dry Film). The deposition mode can be chemical vapor deposition or physical vapor deposition. The material of the substrate 11 may be at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III/V compound semiconductors. The material of the support layer 12 may be any suitable dielectric material, including but not limited to one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, etc., but the technology of the present invention is not limited thereto. In other embodiments, the first substrate 1 may be a single-layer structure, and the material is referred to as the base 11.

In the present embodiment, the cross-sectional shape of the first cavity 121 may be a rectangle, but in other embodiments of the present invention, the cross-sectional shape of the first cavity 121 may also be a circle, an ellipse, or a polygon other than a rectangle, such as a pentagon, a hexagon, etc.

The piezoelectric laminated structure 3 is arranged above the first cavity 121, the piezoelectric layer 32 covers the first cavity 121, and the edges of the first electrode 31 and the second electrode 33 are located within the boundary of the area enclosed by the first cavity 121.

The second electrode 33 and the first electrode 31 may be the same or different in shape. In the present embodiment, the second electrode 33 and the first electrode 31 are the same in shape and are each a polygon with two non-parallel sides, the second electrode 33 and the first electrode 31 are completely overlapped in a direction perpendicular to the piezoelectric layer 32, edges of the first electrode 31 and the second electrode 33 define a boundary of the effective resonance region, that is, the edges of the first electrode 31 and the second electrode 33 are the boundary of the effective resonance region, and the first electrode 31 and the second electrode 33 exist only above the first cavity 121. The first electrode 31 and the second electrode 33 are not overlapped with each other in the ineffective resonance area along the direction vertical to the surface of the piezoelectric layer, so that the problem of high-frequency coupling caused by potential floating can be avoided, and the Q value of the resonator is favorably improved.

In general, any suitable conductive material or semiconductor material known in the art can be used for the second electrode 33 and the first electrode 31, wherein the conductive material can be a metal material having conductive property, for example, made of one of metals such as molybdenum (Mo), aluminum (Al), copper (Cu), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Cr), titanium (Ti), gold (Au), osmium (Os), rhenium (Re), palladium (Pd), or a stack of the above metals, or a semiconductor material such as Si, Ge, SiGe, SiC, SiGeC, or the like. The second electrode 33 and the first electrode 31 may be formed by physical vapor deposition such as magnetron sputtering, evaporation, or chemical vapor deposition.

As a material of the piezoelectric layer 32, a piezoelectric material having a wurtzite crystal structure such as aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), Quartz (Quartz), potassium niobate (KNbO3), or lithium tantalate (LiTaO3), and a combination thereof can be used. When the piezoelectric layer 32 comprises aluminum nitride (AlN), the piezoelectric layer 32 may further comprise a rare earth metal, such as at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). Further, when the piezoelectric layer 32 includes aluminum nitride (AlN), the piezoelectric layer 32 may further include a transition metal, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). Piezoelectric layer 32 may be deposited using any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition. In the present embodiment, the second electrode 33 and the first electrode 31 are made of molybdenum metal (Mo), and the piezoelectric layer 32 is made of aluminum nitride (AlN).

In order to facilitate the subsequent input/output of the electrical signal, the piezoelectric resonator further comprises a first electrode leading-out structure 4 and a second electrode leading-out structure 5, wherein the first electrode leading-out structure 4 is used for connecting the edge of the first electrode 31 and extending to the invalid resonance area as a first signal connecting end, a first gap 43 is enclosed between the edge of the first electrode 31 and the piezoelectric layer 32, the second electrode leading-out structure 5 is used for connecting the edge of the second electrode 33 and extending to the invalid resonance area as a second signal connecting end, and a second gap 53 is enclosed between the edge of the second electrode 33 and the piezoelectric layer 32. It should be noted that the first signal connection terminal may be used as a signal input terminal to introduce an electrical signal into the first electrode 31 of the effective resonance area, and may also be used as a signal output terminal to output an electrical signal on the first electrode 31, and similarly, the second signal connection terminal may also be used as a signal input terminal or a signal output terminal, and when the first signal connection terminal is used as a signal input terminal, the second signal connection terminal is used as a signal output terminal, and vice versa. After the first signal connecting end and the second signal connecting end are connected with the alternating current, the first signal connecting end and the second signal connecting end are respectively used as a signal input end and a signal output end and are in a dynamic change process.

In the present embodiment, the height of the first gap 43 is greater than the thickness of the first electrode 31 so that the entire edge of the first electrode 31 is exposed to the air, and likewise, the height of the second gap 53 is greater than the thickness of the second electrode 33 so that the entire edge of the second electrode 33 is exposed to the air. In other embodiments, the height of the first gap 43 may be equal to or less than the thickness of the first electrode 31; the height of the second gap 53 may also be equal to or less than the thickness of the second electrode 33. The effect is best when the edges of the first electrode 31 are fully exposed to air and the edges of the second electrode 33 are fully exposed to air. The edges of the first electrode 31 and the second electrode 33 form a reflection interface with air, so that acoustic impedance is mismatched, transverse wave leakage is suppressed, an effect of eliminating boundary clutter of an effective resonance area is achieved, and a quality factor (Q value) of the resonator is improved. In addition, the energy coupled into the first electrode 31 and the second electrode 33 is reduced, so that the first electrode 31 and/or the second electrode 33 are prevented from being worn to influence the quality factor (Q value) of the resonator, and the quality factor (Q value) of the resonator in the whole working frequency band is improved. In this embodiment, the projections of the first and

second gaps

43 and 53 are located in the first cavity 121. In other embodiments, the projections of the first and

second gaps

43 and 53 may also be located outside the first cavity 121.

In the present embodiment, the first gap 43 and/or the second gap 53 is an air gap. In other embodiments, the first gap 43 and/or the second gap 53 may be a vacuum gap, or may be other gas medium gaps. In the present embodiment, the projections of the first and

second gaps

43 and 53 on the piezoelectric layer 32 enclose a closed ring shape or a ring shape with a gap.

The first electrode lead-out structure 4 includes: a first overhead part 41 enclosing a first gap 43, and a first bridging part 42 connecting the first overhead part 41 and extending to the ineffective resonance area, the first bridging part 42 serving as a first signal connection terminal. Specifically, the first electrode lead-out structure 4 includes a first overhead portion 41 and a first bridging portion 42, the first overhead portion 41 and the piezoelectric laminated structure 3 enclose a first gap 43, the first bridging portion 42 connects the first overhead portion 41 and extends to the ineffective resonance region, and the first bridging portion 41 is connected for connecting a first external signal.

In the present embodiment, referring to fig. 1, the piezoelectric layer 32 covers the first cavity 121, and the surface of the first land 42 facing the piezoelectric layer 32 is flush with the surface of the first electrode 31 facing the piezoelectric layer 32; and/or the surface of the second land 52 facing the piezoelectric layer 32 is flush with the surface of the second electrode 52 facing the piezoelectric layer 32. The surfaces of the first bridging portion 42 and the second bridging portion 52 facing the piezoelectric layer 32 are flush with the surface of the piezoelectric layer 32, so that the flatness of the whole piezoelectric laminated structure can be ensured, and the performance of the resonator can be ensured.

In the present embodiment, the first bridging portion 42 surrounds the outer periphery of the first electrode 31. In another embodiment, the first overlapping portion 42 is disposed at a portion of the outer periphery of the first electrode 31, such as at a side of the first electrode.

In the present embodiment, the first hollow portion 41 surrounds the outer periphery of the first electrode 31. In other embodiments, the first hollow portion 41 may be connected to one or more edges of the first electrode 31, and in this case, the number of the first hollow portions 41 connecting the first electrode 31 and one first bridging portion 42 may be plural.

Referring to fig. 1A, fig. 1A is a top view of fig. 1 along the X direction. Referring to fig. 1A, the first overlapping portion 42 and the first overhead portion 41 are both disposed at one side of the first electrode 31.

Referring to fig. 1A, the projection of the first hollow portion 41 on the piezoelectric layer 32 is in a strip shape or a planar shape, and when the projection is in the planar shape, the projection may be continuously or discontinuously distributed on one or more edges of the first electrode 31; similarly, the projection of the first land 42 on the piezoelectric layer 32 may be a stripe or a plane; correspondingly, the combination of the first overhead part 41 and the first bridging part 42 may be multiple, for example, the first overhead part 41 and the first bridging part 42 are both strip-shaped or planar, or one of them is a strip-shaped structure, and the other is a planar structure, further, the first overhead part 41 and the first bridging part 42 are both planar, so as to increase the contact area between the first electrode 31 and the first electrode lead-out structure 4, which is beneficial to reducing impedance and improving the Q value of the resonator.

With continued reference to fig. 1, the second electrode lead-out structure 5 includes: a second overhead part 51 surrounding a second gap 53, and a second bridging part 52 connecting the second overhead part 51 and extending to the ineffective resonance area, wherein the second bridging part 52 is used as a second signal connection terminal.

Specifically, the second electrode lead-out structure 5 includes a second raised hollow portion 41 and a second bridging portion 52, the second hollow portion 51 and the piezoelectric laminated structure 3 enclose a second gap 53, and the second bridging portion 52 connects the second hollow portion 51 and extends to the ineffective resonance region.

In the present embodiment, the second bridging portion 52 surrounds the outer periphery of the second electrode 33. In other embodiments, the second overlapping portion 52 is provided at a portion of the outer circumference of the second electrode 33.

In the present embodiment, the second hollow portion 51 surrounds the outer periphery of the second electrode 33. In other embodiments, the second hollow parts 51 are connected to one or more edges of the second electrode 33, and in this case, the number of the second hollow parts 51 connecting the second electrode 33 and one second bridging part 52 may be multiple.

Referring to fig. 1A, the second overhead part 51 is connected to both sides of the second electrode 33, and the second overlapping part 52 is led out from one side. The structures of the second overhead portion 51 and the second land portion 52 and the positional relationship with the second electrode are referred to the structures of the first overhead portion 41 and the first land portion 42 and the positional relationship with the first electrode 31. And will not be described in detail herein.

In this embodiment, the projections of the first electrode lead-out structure 4 and the second electrode lead-out structure 5 on the surface of the piezoelectric layer 32 are staggered, so as to avoid high-frequency coupling caused by potential floating and prevent parasitic capacitance effect. Specifically, the projections of the second land 52 and the first land 42 in the surface direction of the piezoelectric layer 32 are shifted, and the projections of the first and second

overhead parts

41 and 51 in the surface direction of the piezoelectric layer 32 are shifted. At this time, the clutter cancellation effect is optimal.

The materials of the first electrode leading-out structure 4 and the first electrode 31 and/or the materials of the second electrode leading-out structure 5 and the second electrode 33 may be the same or different, the first electrode leading-out structure 4 and/or the second electrode leading-out structure 5 are made of metal materials with small impedance so as to ensure good electrical connection effect, and the metal materials include one or more of gold, silver, tungsten, platinum, aluminum and copper.

In another embodiment, referring to fig. 2, the thin film bulk acoustic resonator further includes: the first bulges 6 and the second bulges 7, the first bulges 6 are positioned on the first electrode 31 and distributed along the edge of the effective resonance area, and the first bulges 6 and the first gaps 43 form a closed ring shape or a ring shape with gaps in the projection of the surface of the piezoelectric layer 32; the second protrusions 7 are located on the second electrode 33 and distributed along the edge of the effective resonance region, and the second protrusions 7 and the projection of the second gap 53 on the surface of the piezoelectric layer 32 form a closed or annular shape with a gap. Specifically, the first protrusion 6 is a continuous whole or includes a plurality of first sub-protrusions intermittently provided, and the second protrusion 7 is a continuous whole or includes a plurality of second sub-protrusions intermittently provided.

Referring to fig. 2A, when the first protrusion 6 is a continuous whole, the projection of the first protrusion 6 on the piezoelectric layer 32 is a continuous pattern, and when the second protrusion 7 is a continuous whole, the projection of the second protrusion 7 on the piezoelectric layer 32 is a continuous pattern, it is understood that it is more advantageous to prevent the lateral leakage of the acoustic wave when the respective projections of the first protrusion 6 and the second protrusion 7 on the piezoelectric layer 32 are continuous patterns. When the first projection 6 includes a plurality of first sub-projections arranged intermittently; and/or when the second protrusion 7 comprises a plurality of discontinuously arranged second sub-protrusions, the projection of the first protrusion 6 on the piezoelectric layer 32 is in a discontinuous pattern; and/or the projection of the second protrusions 7 on the piezoelectric layer 32 is in a discontinuous pattern. When the first bump 6 includes a plurality of first sub-bumps and the second bump 7 includes a plurality of second sub-bumps, projections of the first bump 6 and the second bump 7 on the plane of the piezoelectric layer 32 may overlap, and their projections enclose a ring shape with a gap. In other embodiments, the projections of the first protrusion 6 and the second protrusion 7 in the plane of the piezoelectric layer 32 may not overlap.

In this embodiment, the projections of the first protrusion 6 and the first gap 43 on the surface of the piezoelectric layer 32 form a closed or gapped ring, and the projections of the second protrusion 7 and the second gap 53 on the surface of the piezoelectric layer 32 form a closed or gapped ring, so that the region where the first protrusion 6 and the first gap 43, and the region where the second protrusion 7 and the second gap 53 are located, and the effective resonance region form an acoustic impedance mismatch, and thus, the outward propagating transverse sound wave can be reflected back into the effective resonance region, so as to suppress leakage of transverse noise, reduce energy loss, and improve the quality factor (Q value) of the resonator. When the projection of the first protrusion 6 and the first hollow part 41 on the surface of the piezoelectric layer 32 is a closed ring shape, and the projection of the second protrusion 7 and the second hollow part 51 on the surface of the piezoelectric layer 32 is a closed ring shape, it is more beneficial to prevent the lateral leakage of the acoustic wave. The material of the first protrusion 6 and the second protrusion 7 may be a dielectric material or a conductive material, and when the material of the first protrusion 6 and/or the second protrusion 7 is a dielectric material, it may be any one of silicon oxide, silicon nitride, silicon oxynitride, or silicon carbonitride, but is not limited thereto. When the material of the first bump 6 and/or the second bump 7 is a conductive material, the material of the first bump 6 is the same as the material of the first electrode 31; and/or the material of the second bump 7 is the same as the material of the second electrode 33.

With continuing reference to figures 2 and 2A, in yet another embodiment, the thin film bulk acoustic resonator further comprises: a first dielectric layer 95 and a second dielectric layer 96, the first dielectric layer 95 being located between the first substrate 1 and the piezoelectric layer 32, the first dielectric layer 95 being located in the ineffective resonance region and being spaced apart from the first electrode 31, the first dielectric layer 95 and the first junction 42 surrounding the first electrode 31; a second dielectric layer 96 is located over the piezoelectric layer 32, the second dielectric layer 96 and the second land 52 surrounding the second electrode 33, and the second dielectric layer 96 and the second land 52 surrounding the second electrode 33. The first dielectric layer 95 and the second dielectric layer 96 can improve the bonding effect when the top cover is bonded subsequently; meanwhile, the arrangement of the first dielectric layer 95 and the second dielectric layer 96 can also improve the mechanical strength of the whole resonator. It is noted that the overall mechanical strength performance is best when the upper surface of the first dielectric layer 95 is flush with the upper surface of the first strap 42 and the upper surface of the second dielectric layer 96 is flush with the upper surface of the second strap 52. Furthermore, the first dielectric layer 95 may be continuously connected to the first bridging portion 42, that is, the first dielectric layer 95 and the first bridging portion 42 are connected to each other on the surface of the piezoelectric layer 32, and form a ring on the surface of the piezoelectric layer 32, and fill the area outside the edge of the effective resonance area; the second dielectric layer 96 may be continuous with the second land 52, i.e., the second dielectric layer 96 may be continuous with the second land 52 at the surface of the piezoelectric layer 32, and may form a ring shape at the surface of the piezoelectric layer 32, and may fill the area outside the edge of the effective resonance area. When the first dielectric layer 95 and the first bridging portion 42 are continuously connected and the second dielectric layer 96 and the second bridging portion 52 are continuously connected, it is more advantageous to ensure the flatness of the piezoelectric laminated structure 3 to improve the strength of the resonator. The first dielectric layer 95 may be any suitable dielectric material, including but not limited to at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, and the like, and the material of the second dielectric layer 96 may be selected according to the material of the first dielectric layer 95, which is not described herein again. In this embodiment, the material of the second dielectric layer 96 may be the same as that of the first dielectric layer 95.

It should be understood that the raised structures and the dielectric layer structures are independent of each other, and in other embodiments, only the raised structures may be included, or only the dielectric layer structures may be included. When the first protrusion 6, the second protrusion 7, the first dielectric layer 95, and the second dielectric layer 96 are included at the same time, it is possible to more advantageously suppress the leakage of the transverse wave, balance the temperature drift, improve the mechanical strength, and improve the effect of the top cap bonding.

In another embodiment, referring to fig. 3, in order to prevent the layers exposed in the upper space from being contaminated by the external environment, a top cover 8 is further disposed above the piezoelectric stack structure, the top cover 8 has a second cavity 811 therein, the second cavity 811 is located above the first cavity 121, and the edge of the second electrode 33 is located in the second cavity 811.

Specifically, the top cover 8 may be of unitary construction, with the second cavity 811 not extending through the top cover 8; alternatively, the top cover includes the bonding layer 81 and the second substrate 82, the second cavity 811 is formed on the bonding layer 81, the second cavity 811 may or may not penetrate the bonding layer 81, and the second substrate 82 is bonded above the bonding layer 81. The bonding layer 81 may be silicon oxide, silicon nitride, silicon oxynitride, ethyl silicate, or an adhesive such as a photo-curable material or a thermosetting material, for example, a Die tth Film (DF) or a Dry Film (Dry Film). The material of the bonding layer 81 and the material of the second substrate 82 may be the same, and both may be of a unitary structure, that is, the top cover 8 is of a unitary structure, and the second cavity 811 is formed by forming a space in the top cover 8.

In the present embodiment, referring to fig. 4, an air gap 321 is further disposed on the piezoelectric layer 32 and communicates with the first cavity 121, and the air gap 321 serves as a release hole for releasing the sacrificial material filled in the first cavity. On the other hand, the edges of the piezoelectric layer 32 can be exposed to air, so that the transverse wave can be effectively suppressed. Specifically, the air gap 321, the first hollow portion and the second hollow portion are offset from each other in projection on the piezoelectric layer 32, and enclose a closed ring shape or a ring shape with a gap.

Specifically, the air gap 321 may be one or more through holes distributed on the periphery of the piezoelectric layer above the first cavity 121 and outside the effective resonance area, or the air gap 321 may be an unclosed ring structure having a certain length. The air gap 321 connects the first cavity 121 and the second cavity 811.

In other embodiments, piezoelectric layer 32 can be a complete membrane layer. Maintaining the integrity of the membrane layers of the piezoelectric layer 32 can improve the structural strength of the piezoelectric layer 32 and thus improve resonator yield.

Fig. 5 is a flowchart illustrating steps of a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present invention, and referring to fig. 5, the method for manufacturing a thin film bulk acoustic resonator includes:

s01: providing a temporary substrate;

s02: sequentially forming a second electrode layer, a piezoelectric layer and a first electrode on the temporary substrate, wherein the first electrode is positioned in the effective resonance area;

s03: forming a first electrode leading-out structure, wherein the first electrode leading-out structure is connected with the edge of the first electrode and extends to the invalid resonance area to be used as a first signal connecting end, and a first gap is formed by the edge of the valid resonance area, the piezoelectric layer and the first electrode;

s04: forming a first sacrificial layer covering the first electrode and the first electrode leading-out structure positioned at the boundary of the effective resonance area;

s05: forming a first substrate covering the first sacrificial layer and the piezoelectric layer;

s06: removing the temporary substrate;

s07: patterning the second electrode layer to form a second electrode, wherein the first electrode, the piezoelectric layer and the second electrode form a piezoelectric laminated structure; the region where the first electrode, the piezoelectric layer, and the second electrode overlap each other in a direction perpendicular to the surface of the piezoelectric layer constitutes an effective resonance region of the resonator;

s08: forming a second electrode leading-out structure, wherein the second electrode leading-out structure is connected with the edge of the second electrode and extends to the invalid resonance area to be used as a second signal connecting end, and a second gap is formed by the edge of the valid resonance area, the piezoelectric layer and the second electrode;

s09: the first sacrificial layer is removed.

Fig. 6 to 14 are schematic structural diagrams corresponding to respective steps of a method for manufacturing a thin film bulk acoustic resonator according to this embodiment, and the method for manufacturing a thin film bulk acoustic resonator according to this embodiment will be described in detail below with reference to fig. 6 to 14.

Referring to fig. 6, step S01 is performed to provide a temporary substrate 90.

The material of the temporary substrate 90 may be the material of the first substrate 1, and is not described herein.

In addition, an isolation layer 97 may also be formed on the temporary substrate 90 to facilitate subsequent peeling of the temporary substrate 90. In the subsequent stripping process, the temporary substrate 90 may be separated from the subsequently formed second electrode layer by etching the isolation layer, which is helpful for rapidly stripping the temporary substrate 90 and improving the process manufacturing efficiency. If the isolation layer 97 is not formed between the temporary substrate 90 and the second electrode layer formed in the subsequent process, the temporary substrate 90 may be removed by mechanical polishing or the like. The material of the isolation layer 97 includes, but is not limited to, at least one of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), and aluminum nitride (AlN). The isolation layer 97 can be formed by chemical vapor deposition, magnetron sputtering, or evaporation. In this embodiment, the temporary substrate 90 is monocrystalline silicon, and the isolation layer 97 is silicon dioxide (SiO 2).

With continuing reference to fig. 6, step S02 is performed to form the second electrode layer 33', the piezoelectric layer 32, and the first electrode 31 in that order on the temporary substrate 90, the first electrode 31 being located in the effective resonance region. The piezoelectric layer 32 is located between the first electrode 31 and the second electrode layer 33 ', and the first electrode 31 and the second electrode layer 33' are oppositely disposed. Note that when the isolation layer 97 is formed on the temporary substrate 90, the second electrode layer 33' is formed on the isolation layer 97.

The second electrode layer 33 ' is first deposited on the temporary substrate 90, then the piezoelectric layer 32 is deposited on the second electrode layer 33 ', and finally the first electrode layer 31 ' is deposited on the piezoelectric layer 32. Through a deposition process, the second electrode layer 33 'and the piezoelectric layer 32 are sequentially formed on the surface of the temporary substrate 90, so that the piezoelectric layer 32 is formed on the flat second electrode layer 33', and therefore the piezoelectric layer 32 is ensured to have better lattice orientation, the piezoelectric property of the piezoelectric layer 32 is improved, and the overall performance of the resonator is further improved.

The first electrode layer 31 'is used for the subsequent formation of the first electrode 31, and the second electrode layer 33' is used for the subsequent formation of the second electrode 33. The materials of the first electrode layer 31 ', the second electrode layer 33' and the piezoelectric layer can be referred to the materials of the first electrode 31, the second electrode 33 and the piezoelectric layer 32 in the foregoing structural embodiment section, respectively. The first electrode layer 31 'or the second electrode layer 33' may be formed by physical vapor deposition such as magnetron sputtering or evaporation, or by chemical vapor deposition. Piezoelectric layer 32 may be deposited using any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition.

After the first electrode layer 31 'is formed, the first electrode layer 31' is patterned to form the first electrode 31, and the method for patterning the first electrode layer 31 'may etch the first electrode layer 31' by using an etching process, which may be a wet etching process or a dry etching process, wherein a dry etching process is preferably used, and the dry etching process includes, but is not limited to, Reactive Ion Etching (RIE), ion beam etching, plasma etching or laser cutting. In the present embodiment, the boundary of the first electrode 31 exists only within the boundary of the effective resonance region.

In other embodiments, after forming the piezoelectric layer 32, a mask layer may be formed on the piezoelectric layer 32, where the mask layer exposes a portion of the surface of the piezoelectric layer 32, and the first electrode layer 31' is deposited on the piezoelectric layer 32 and the mask layer; and removing the mask layer and the first electrode layer 31' positioned on the mask layer to form the first electrode. By forming a mask layer on the piezoelectric layer 32 to facilitate the patterning of the first electrode 31, it is ensured that the piezoelectric layer 32 is not etched, thereby ensuring the integrity of the piezoelectric layer 32 and further improving the structural stability of the resonator.

Before forming the second electrode layer 33 ', a seed layer may also be formed on the temporary substrate 90 or the isolation layer 97, so that the second electrode layer 33' is formed on the seed layer, and the seed layer has guidance for the crystal directions of the subsequently formed second electrode layer 33 ', the piezoelectric layer 32, and the first electrode layer 31', thereby facilitating the growth of the second electrode layer 33 ', the piezoelectric layer 32, and the first electrode layer 31' along a specific crystal direction, and ensuring the uniformity of the piezoelectric layer 32. The seed layer may be made of aluminum nitride (AlN), and may be formed using a metal or a dielectric material having a hexagonal close-packed (HCP) structure, in addition to AlN. For example, the seed layer may be formed of titanium (Ti) metal.

With continuing reference to fig. 7, step S03 is performed to form the first electrode lead-out structure 4, where the first electrode lead-out structure 4 connects the edge of the first electrode 31 and extends to the inactive resonance area as the first signal connection end, and a first gap is defined by the edge of the active resonance area, the piezoelectric layer 32 and the first electrode 31. In the present embodiment, the effective resonance region includes a region where the first electrode 31, the piezoelectric layer 32, and the second electrode overlap each other in a direction perpendicular to the surface of the piezoelectric layer 32, the ineffective resonance region is a region other than the effective resonance region, and the edge of the effective resonance region is defined by the edges of the first electrode 31 and the second electrode.

In the present embodiment, the first electrode lead-out structure 4 includes a first overhead portion 41 and a first bridging portion 42, the first overhead portion 41, the piezoelectric layer 32 and the first electrode 31 enclose a first gap, the first bridging portion 42 connects the first overhead portion 41 and extends to the ineffective resonance region, and the first bridging portion 42 is used for connecting a first external signal. It should be noted that the first external signal may be an input signal or an output signal.

The method of forming the first electrode lead-out structure 4 includes:

forming a first sacrificial protrusion 92 on an edge of the first electrode 31, where the first sacrificial protrusion 92 is located on the first electrode 31 and on a sidewall of the first electrode 31, or the first sacrificial protrusion 92 is located on a sidewall of the first electrode 31;

forming a first conductive layer overlying the piezoelectric layer 32 and the first sacrificial protrusion 92;

the first conductive layer is patterned to form the first electrode lead-out structure 4.

Specifically, referring to fig. 7, first, a first sacrificial protrusion material layer is formed on the piezoelectric layer 32, the first sacrificial protrusion material layer covers the first electrode 31 and the piezoelectric layer 32, the first sacrificial protrusion material layer is patterned, and a first sacrificial protrusion 92 is formed outside the edge of the first electrode 31 and close to the sidewall of the first electrode 31, or the first sacrificial protrusion 92 may be located on the first electrode 31 and extend onto the piezoelectric layer 32. In this embodiment, the top of the first sacrificial protrusion 92 is higher than the surface of the first electrode 31, but it should be understood that the top of the first sacrificial protrusion 92 may also be not higher than the surface of the first electrode 31, and only when the top of the first sacrificial protrusion 92 is higher than the surface of the first electrode 31, the edge of the first electrode 31 can be completely exposed in the first gap when the first gap is formed after the first sacrificial protrusion 92 is subsequently removed, so that the loss of the transverse wave can be better suppressed. The first sacrificial protrusion 92 may have a step-shaped protrusion structure or a column-shaped structure, and the shape of the first sacrificial protrusion 92 is not limited thereto. In this embodiment, the first sacrificial bump material layer comprises phosphosilicate glass, low temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide, or photoresist.

The first sacrificial protrusion 92 is formed when the first electrode lead-out structure 4 is formed, so that the first electrode lead-out structure 4, the piezoelectric layer 32 and the first electrode 31 enclose a first gap to expose the edge of the first electrode 31, thereby effectively suppressing transverse waves and improving the Q value of the resonator.

With continued reference to fig. 7, a first conductive layer is formed overlying the piezoelectric layer 32, the first electrode 31, and the first sacrificial protrusion 92; the first conductive layer is patterned to form the first electrode lead-out structure 4. In the present embodiment, the first electrode lead-out structure 4 includes the first overhead portion 41 covering the first sacrificial protrusion 92 and the first land portion 42 located on the surface of the piezoelectric layer 32, the first land portion 42 being electrically connected to an external signal, the first overhead portion and the first land portion being electrically connected. The material of the first electrode lead-out structure 4 is as described above with reference to the structural embodiment.

In the present embodiment, the first hollow portion 41 forms a closed ring shape around the outer periphery of the first electrode 31. In another embodiment, the first overhead portion 41 is connected to one or more edges of the first electrode 31. The projection of the first hollow part on the piezoelectric layer can be strip-shaped or planar, and when the projection is planar, the projection can be continuously or discontinuously distributed on one or more edges of the second electrode; similarly, the projection of the first bridging part on the piezoelectric layer can also be strip-shaped or planar; correspondingly, the combination of the first overhead part and the first bridging part can be multiple, for example, when the first overhead part and the first bridging part are both strip-shaped or planar, or one of the first overhead part and the first bridging part is a strip-shaped structure and the other is a planar structure, specifically, when the first overhead part and the first bridging part are both planar, the contact area between the first electrode and the first electrode leading-out structure can be increased, which is beneficial to reducing impedance and improving the Q value of the resonator.

Referring to fig. 8, step S04 is performed to form a first sacrificial layer 91 covering the first electrode 31 and the first electrode lead-out structure 4 located at the boundary of the effective resonance area. In this embodiment, the first sacrifice layer 91 covers the area above the first overhead portion 41. In other embodiments, the first sacrificial layer 91 may cover part of the first hollow portion 41, or may not cover the first hollow portion 41. The material of the first sacrificial layer 91 includes any one of phosphosilicate glass, low-temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide, or photoresist. The formation method of the first sacrificial layer 91 may be different according to the material, and the formation process of the first sacrificial layer 91 includes a deposition process or a spin coating process. The first cavity is formed by adopting the first sacrificial layer 91, so that the first substrate 91 is supported in the process of forming the first substrate, the piezoelectric laminated structure 3 is prevented from being pressed and deformed due to uneven stress, and the piezoelectric layer is supported in the subsequent reverse process, so that the flatness of the piezoelectric laminated structure 3 is ensured.

Referring to fig. 9, step S05 is performed to form a first substrate 1 covering the first sacrificial layer 91 and the piezoelectric layer 32. In the present embodiment, the first substrate 1 includes a base 11 and a support layer 12, and the method of forming the first substrate 1 includes: the support layer 12 is formed, the support layer 12 covers the first sacrificial layer 91 and the piezoelectric layer 32 and the first electrode lead-out structure 4, and the method of forming the support layer 12 may employ a deposition process. A substrate 11 is provided bonded to a support layer 12. The bonding of the support layer 12 and the substrate 11 can be achieved as described in the previous structural embodiments. The materials of the support layer 12 and the substrate 11 can also be referred to the relevant description in the previous structural embodiments.

In other embodiments, the first substrate 1 may be a unitary structure, the first substrate 1 covering the first sacrificial layer 91 and the piezoelectric layer 32. The first substrate 1 may be formed by a chemical vapor deposition method or a physical vapor deposition method, and the material of the first substrate 1 may refer to the material of the temporary substrate 90, which is not described herein again.

Referring to fig. 10, after the bonding process is completed, step S06 is performed to remove the temporary substrate 90 and turn over the bonded thin film bulk acoustic resonator. When the isolation layer 97 is formed between the temporary substrate 90 and the second electrode layer 33, the temporary substrate 90 may be peeled off by etching the isolation layer 97; when no isolation layer 97 is formed between the temporary substrate 90 and the second electrode layer 33, the temporary substrate 90 may be removed by other methods, such as etching or mechanical polishing.

Referring to fig. 11, step S07 is executed, when the resonator is turned over, the second electrode layer 33' is patterned to form the second electrode 33, the first electrode 31, the piezoelectric layer 32 and the second electrode 33 form the piezoelectric stack 3, the effective resonance area includes an area where the first electrode 31, the piezoelectric layer 32 and the second electrode 33 overlap each other in a direction perpendicular to the surface of the piezoelectric layer 32, and the ineffective resonance area is an area other than the effective resonance area. The second electrode 33 remains in a portion of the effective resonance region, and the method of patterning the second electrode layer 33 'is the same as the method of patterning the first electrode layer 31', and thus, a detailed description thereof is omitted. In this embodiment, the second electrode 33 and the first electrode 31 have the same shape and are both irregular polygons, and projections of the second electrode 33 and the first electrode 31 in the direction of the piezoelectric layer 32 are completely overlapped.

Referring to fig. 11, step S08 is performed to form a second electrode lead-out structure 5, where the second electrode lead-out structure 5 connects the edge of the second electrode 33 and extends to the inactive resonance region as a second signal connection terminal, and a second gap 53 is defined between the edge of the active resonance region and the piezoelectric stack structure 3. It should be noted that the second signal connection terminal can be used as a signal input terminal and also can be used as a signal output terminal, when the first signal connection terminal is used as a signal input terminal, the second signal connection terminal is used as a signal output terminal, and vice versa, when the alternating current is switched in, the first signal connection terminal and the second signal connection terminal are respectively used as a signal input terminal and a signal output terminal and are in a dynamic change process. The second electrode lead-out structure 5 may be a planar type or a strip type. Specifically, when the second electrode lead-out structure 5 is planar, the areas of the second electrode 33 and the second electrode lead-out structure 5 can be increased, which is beneficial to reducing impedance and improving the Q value of the resonator.

With continued reference to fig. 11, in the present embodiment, the second electrode lead-out structure 5 includes a second overhead portion 51 and a second bridging portion 52, the second overhead portion 51 and the piezoelectric layer 32 and the second electrode 33 enclose a second gap 53, the second bridging portion 52 connects the second overhead portion 51 and extends to the ineffective resonance region, and the second bridging portion 52 is used for connecting a second external signal.

The method of forming the second electrode lead-out structure 5 includes:

forming a second sacrificial protrusion 93 at an edge of the second electrode 33, where the second sacrificial protrusion 93 is located on the second electrode 33 and on a sidewall of the second electrode 33, or the second sacrificial protrusion 93 is located on a sidewall of the second electrode 33;

forming a second conductive layer covering the piezoelectric layer 32 and the second sacrificial protrusion 93;

and patterning the second conductive layer to form a second electrode lead-out structure 5.

Specifically, a second sacrificial protrusion material layer is formed first, the second sacrificial protrusion material layer covers the second electrode 33 and the piezoelectric layer 32, the second sacrificial protrusion material layer is patterned, and a second sacrificial protrusion is formed outside the edge of the second electrode 33 and abutting against the sidewall of the second electrode 33, or the second sacrificial protrusion may be located on the second electrode 33 and extend onto the piezoelectric layer 32. In this embodiment, the top of the second sacrificial protrusion is higher than the surface of the second electrode 33, it should be understood that the top of the second sacrificial protrusion may also be not higher than the surface of the second electrode 33, but when the top of the second sacrificial protrusion is higher than the surface of the second electrode 33, the edge of the second electrode 33 can be completely exposed in the second gap 33 when the second gap 53 is formed after the second sacrificial protrusion is subsequently removed, and the loss of the transverse wave can be better suppressed. The shape and material of the second sacrificial protrusion refer to those of the first sacrificial protrusion, and the material of the second electrode lead-out structure 5 refers to those described in the foregoing structural embodiments.

In this embodiment, the second electrode lead-out structure 5 includes a second overhead portion 51 covering the second sacrificial protrusion and a second bridging portion 52 located on the surface of the piezoelectric layer 33, the second bridging portion 52 extends to the periphery of the first cavity 21, the second bridging portion 52 is electrically connected to the second external signal terminal, and the second overhead portion is electrically connected to the second bridging portion.

In addition, the second sacrificial protrusion is formed by adopting a sacrificial material method, so that a support can be formed when the second electrode leading-out structure 5 is formed, the structural strength of the second electrode leading-out structure is ensured, meanwhile, the piezoelectric layer 32 is ensured not to be pressed and deformed, and further, the integral structure stability of the formed resonator is ensured.

In this embodiment, the projections of the first electrode lead-out structure and the second electrode lead-out structure on the surface of the piezoelectric layer are staggered.

Specifically, the projections of the first overlapping part and the second overlapping part on the surface of the piezoelectric layer are mutually staggered, so that the coupling effect caused by potential floating is avoided, and the parasitic effect is prevented.

With continued reference to fig. 11, step S09 is performed to remove the first sacrificial layer. And when the first sacrificial layer is removed, removing the sacrificial protrusion. Specifically, a first release hole is formed through the piezoelectric layer 32 to expose the first sacrificial layer, and the first sacrificial layer is removed through the first release hole; and forming a second release hole penetrating through the electrode lead-out structure to expose the sacrificial protrusion, and removing the sacrificial protrusion through the second release hole.

In the present embodiment, in order to facilitate removal of the first sacrificial layer after the formation of the second electrode lead-out structure 5, it is necessary to form the air boundary 321 that penetrates the piezoelectric layer 32 and communicates with the first sacrificial layer when forming the piezoelectric layer 32. The air gaps 321 may be formed by etching, and the structure and distribution of the air gaps 321 can be described in the foregoing structural embodiments, which are not described herein again.

In the process of removing the first sacrificial layer, according to the material of the first sacrificial layer, a corresponding removal method is adopted, for example, when the material of the first sacrificial layer is polyimide or photoresist, an ashing method is adopted for removing, specifically, at a temperature of 250 ℃, oxygen chemically reacts with the material of the first sacrificial layer through the air gap 321, generated gas substances are volatilized, when the material of the first sacrificial layer is low-temperature silicon dioxide, a hydrofluoric acid solvent reacts with the low-temperature silicon dioxide for removing, so as to form the first cavity 121, and the shape of the first cavity 121 is the same as that of the first sacrificial layer. It should be noted that, when the first sacrificial protrusion and the first sacrificial layer are made of the same material, the first sacrificial protrusion and the first sacrificial layer can be removed simultaneously through the air gap 321, and in addition, after the first sacrificial layer is removed, the second sacrificial protrusion needs to be removed.

When the first sacrificial layer, the first sacrificial protrusion and the second sacrificial protrusion are removed, the first cavity 121, the first gap 43 and the second gap 53 are formed respectively, and the air side gap 321, the first gap 43 and the second gap 53 can cooperate to play a role in inhibiting transverse waves.

In the present embodiment, the projections of the first and

second gaps

43 and 53 on the piezoelectric layer 32 enclose a closed ring shape or a ring shape with a gap. The contact area between the edge of the first electrode and the edge of the second electrode and the air is increased, the leakage of transverse waves is prevented, and the Q value of the resonator is improved.

The edge area of the effective resonance area is further provided with an air gap 321 which penetrates the piezoelectric layer 32 and communicates with the first cavity 121, so that part of the edge of the piezoelectric layer 32 is exposed to air, thereby effectively suppressing transverse waves.

In this embodiment, the projections of the air side gap 321, the first gap 43, and the second gap 43 on the piezoelectric layer 32 are staggered from each other, and enclose a closed ring or a ring with a gap, so that the transverse wave can be suppressed better.

In the embodiment, the first electrode 31 and the first electrode lead-out structure 4 are formed on the first surface of the piezoelectric layer 32, and then the second electrode 33 and the second electrode lead-out structure 5 are formed on the second surface of the piezoelectric layer 32, so that the process of patterning the electrodes on the two surfaces of the piezoelectric layer avoids the etching of the electrode forming process on the piezoelectric layer, ensures the integrity and the flatness of the piezoelectric layer 32, reduces the influence on the piezoelectric layer, and improves the performance of the resonator.

In other embodiments, referring to fig. 12, further comprising: first protrusions 6 are formed on the first electrode 31, and the first protrusions 6 are distributed along the boundary of the effective resonance region. When the first electrode leading-out structure 4 is formed by etching, a first bulge 6 is also formed by etching, and the material of the first bulge 6 is the same as that of the first electrode leading-out structure 4; alternatively, the first projection 6 is formed after the first electrode lead-out structure 4 is formed; alternatively, the first bump 6 is formed after the first electrode 31 is formed and before the first electrode lead-out structure 4.

With continued reference to fig. 12, further comprising: second protrusions 7 are formed on the second electrode 33, and the second protrusions 7 are distributed along the boundary of the effective resonance region. When the second electrode leading-out structure 5 is formed by etching, a second bulge 7 is also formed by etching, and the material of the second bulge 7 is the same as that of the second electrode leading-out structure 5; alternatively, the second projection 7 is formed after the second electrode lead-out structure 5 is formed; alternatively, the second bump 7 is formed after the second electrode 33 is formed and before the second electrode lead-out structure 5. In this embodiment, the structure, material, distribution and beneficial effects of the first bump 6 and the second bump 7 can refer to the first bump 6 and the second bump 7 described in the structural embodiments, and are not described herein again.

Referring to fig. 13, in another embodiment of the present invention, after forming the first electrode 31, forming a first dielectric layer 95 on the piezoelectric layer 32 in the non-effective resonance region, the first dielectric layer 95 being spaced apart from the first electrode 31, the first dielectric layer 95 being formed between the first substrate 1 and the piezoelectric layer 32, the first dielectric layer 95 and the first bridging portion 42 surrounding the first electrode 31. It should be noted that the first dielectric layer 95 may be formed before or after the first electrode lead-out structure 4 is formed. Similarly, after the second electrode 32 is formed, a second dielectric layer 96 is formed on the piezoelectric layer 32 in the null resonance region so as to be spaced apart from the second electrode 33, and the second dielectric layer 96 and the second bridging portion 52 surround the second electrode 33. It should be noted that the second dielectric layer 96 may be formed before or after the second electrode lead-out structure 5 is formed.

The distribution and advantageous effects of the first dielectric layer 95 with respect to the first bridging portion 42 and the material of the first dielectric layer 95 can be described in the structural embodiments above, the distribution and advantageous effects of the second dielectric layer 96 with respect to the second bridging portion 52 and the material of the second dielectric layer 96 can be described in the structural embodiments above, and the arrangement and advantageous effects of the first dielectric layer 95 with respect to the second dielectric layer 96 can be described in the structural embodiments above, and are not described herein again.

In other embodiments, as shown in fig. 14 to 16, a top cover 8 may be further formed on the piezoelectric stack 3 to prevent the layers exposed in the upper space from being contaminated by the external environment, the top cover 8 having a second cavity 811 therein, and the second electrode 33 being located in the second cavity 811.

Meanwhile, the formed second cavity 811 is matched with the first cavity 121, so that longitudinal waves among the first electrode 31, the piezoelectric layer 32 and the second electrode 33 are transmitted to the first cavity 121 or the second cavity 811 and then reflected back to the effective resonance area, and the utilization rate of sound waves is improved.

Referring to fig. 14, the top cover 8 may further include a bonding layer 81 and a second substrate 82.

In one embodiment, referring to fig. 15-16, a method of forming the top cover 8 includes:

s1: forming a second sacrificial layer 94, the second sacrificial layer 94 covering the second electrode 33 and the second electrode lead-out structure 5 located at the boundary of the effective resonance region;

s2: forming a bonding layer 81 covering the second sacrificial layer 94 and the piezoelectric laminated structure 3;

s3: removing the second sacrificial layer 94 to form a second cavity 811;

s4: a second substrate 82 is formed over the bonding layer 81.

Referring to fig. 11 together with fig. 15, step S1 is performed in which, after step S08 is performed, a second sacrificial layer 94 is formed as shown in fig. 15, the second sacrificial layer 94 covering the second electrode 33 and the second electrode lead-out structure 5 located at the boundary of the effective resonance region. The second sacrificial layer 94 may cover part or all of the second hollow portion 51, or may not cover the second hollow portion 51. The manner of depositing the second sacrificial layer 94 may refer to the manner of depositing the first sacrificial layer 91, and the material of the second sacrificial layer 94 may refer to the material of the first sacrificial layer 91, which are not described herein again.

Referring to fig. 16, when step S2 is performed, the second sacrificial layer forming the bonding layer 81 by a deposition process may cover all of the empty portions, or may cover part of the second empty portions or not cover the second empty portions. Release holes 812 are formed on the bonding layer, the number, size and shape of the release holes 812 are not specifically limited, the sacrificial layer material can be removed cleanly, and the cross section of the release holes 812 can be trapezoidal, rectangular, circular, oval and the like, and is formed by dry etching.

With continued reference to fig. 16, when the step S3 is executed to remove the second sacrificial layer 94, a corresponding removal method needs to be adopted according to the material thereof, and details are not repeated here. It should be noted that the first sacrificial protrusion, the second sacrificial protrusion and the first sacrificial layer 91 can be removed simultaneously with the second sacrificial layer 94 at this step, and at this time, the same kind of sacrificial material is used for the first sacrificial protrusion 92, the second sacrificial protrusion 93, the first sacrificial layer and the second sacrificial layer.

With continued reference to fig. 16, step S4 is performed, and the bonding manner of the bonding layer 81 and the second substrate 82 can refer to the bonding manner of the base 11 and the supporting layer 12, which is not repeated herein.

In this embodiment, the second cavity 811 is formed by using the second sacrificial layer 94, so that the first sacrificial layer 91, the first sacrificial protrusion 92 and the second sacrificial protrusion 93 are combined to form a support in the process of forming the second substrate 82, and the piezoelectric stack structure 3 is prevented from being deformed by pressure due to uneven stress, thereby ensuring that the finally formed resonator has good overall structural stability.

In other embodiments, the top cover 8 may be a unitary structure, and the top cover 8 may be etched to form the second cavity 811 to bond the top cover 8 to the piezoelectric stack. It should be noted that the first sacrificial projections 92, the second sacrificial projections 93 need to be removed before the top cover 8 is formed. The second cavity 811 is formed by etching the second substrate 82, and then the second substrate 82 is bonded to the piezoelectric layer 32, so as to prevent the integrity of the piezoelectric layer 32 from being damaged when the second cavity 811 is etched, thereby ensuring the structural strength of the piezoelectric layer 32.

In summary, in the process of manufacturing the resonator, the first electrode lead-out structure and the second electrode lead-out structure are respectively adopted on the first electrode side and the second electrode side, the first electrode lead-out structure and the second electrode lead-out structure respectively form a first gap and a second gap in the boundary area of the effective resonance area, the first gap and the second gap can achieve the effect of eliminating the boundary noise wave of the effective resonance area, and further the Q value of the resonator is improved.

Furthermore, the piezoelectric layer is provided with a gap edge gap, so that the edge of the piezoelectric layer is exposed in the air, and the loss of transverse waves can be inhibited; when the projections of the gap side gap, the first gap and the second gap on the piezoelectric layer are mutually staggered and enclose a closed ring, the transverse wave loss can be better inhibited.

According to the manufacturing method of the film bulk acoustic resonator, the process of patterning the electrodes on the two sides of the piezoelectric layer is adopted, and the piezoelectric layer is not etched in the whole manufacturing process, so that the integrity and the flatness of the piezoelectric layer are guaranteed, and the piezoelectric layer is further guaranteed to have good piezoelectric characteristics.

It should be noted that, in the present specification, all the embodiments are described in a related manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the structural embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims

1. A thin film bulk acoustic resonator, comprising:

a first substrate having a first cavity therein;

2. The film bulk acoustic resonator according to claim 1, wherein the projections of the first electrode lead-out structure and the second electrode lead-out structure on the surface of the piezoelectric layer are mutually staggered.

3. The film bulk acoustic resonator of claim 1, wherein a projection of the first and second voids on the piezoelectric layer encloses a closed ring shape or a ring shape with a gap.

4. The film bulk acoustic resonator of claim 1, wherein the first electrode lead-out structure comprises: the first bridging part is connected with the first overhead part and extends to the invalid resonance area, and the first bridging part is used as the first signal connecting end;

and/or the presence of a gas in the gas,

the second electrode lead-out structure includes: the second bridging part is connected with the second overhead part and extends to the invalid resonance area, and the second bridging part is used as the second signal connecting end.

5. The film bulk acoustic resonator according to claim 4, wherein the piezoelectric layer covers the first cavity, and a surface of the first land facing the piezoelectric layer is flush with a surface of the first electrode facing the piezoelectric layer;

and/or the presence of a gas in the gas,

the surface of the second land facing the piezoelectric layer is flush with the surface of the second electrode facing the piezoelectric layer.

6. The film bulk acoustic resonator of claim 4,

the first lap joint part surrounds the periphery of the first electrode, or the first lap joint part is arranged on part of the periphery of the first electrode;

the first overhead part surrounds the periphery of the first electrode;

the second lap joint part surrounds the periphery of the second electrode, or the second lap joint part is arranged on part of the periphery of the second electrode;

the second overhead portion surrounds the outer periphery of the second electrode.

7. The film bulk acoustic resonator of claim 1, wherein the material of the first electrode lead-out structure or the second electrode lead-out structure is a metal material, and the metal material comprises one or more of gold, silver, tungsten, platinum, aluminum, and copper.

8. The film bulk acoustic resonator according to claim 1, further comprising a first protrusion and/or a second protrusion, wherein the first protrusion is located on the first electrode and distributed along the boundary of the effective resonance area, and a projection of the first protrusion and the first hollow portion on the surface of the piezoelectric layer is in a closed or annular shape with a gap;

the second bulges are positioned on the second electrode and distributed along the boundary of the effective resonance area, and the projections of the second bulges and the second overhead part on the surface of the piezoelectric layer are closed or in a ring shape with gaps.

9. The thin film bulk acoustic resonator of claim 8, wherein the material of the first bump and the second bump comprises a dielectric material; alternatively, the first and second electrodes may be,

the material of the first bump is the same as that of the first electrode; and/or the material of the second bump is the same as the material of the second electrode.

10. The film bulk acoustic resonator of claim 1, further comprising a first dielectric layer and a second dielectric layer;

the first dielectric layer is positioned between the first substrate and the piezoelectric layer, the first dielectric layer is positioned in the invalid resonance region and is separated from the first electrode, and the first dielectric layer and the first lap joint part surround the first electrode;

the second dielectric layer is located on the piezoelectric layer, the second dielectric layer is located in the invalid resonance region and is separated from the second electrode, and the second dielectric layer and the second lapping portion surround the second electrode.

11. The film bulk acoustic resonator according to claim 1, wherein an air gap penetrating the piezoelectric layer and communicating with the first cavity is further provided at an edge of the effective resonance region.

12. The film bulk acoustic resonator of claim 1, further comprising a top cap having a second cavity therein, the second cavity being located above the first cavity, and the second electrode being located within the second cavity.

13. The thin film bulk acoustic resonator of claim 1, wherein the first substrate includes a base and a support layer, the support layer and the piezoelectric stack structure are sequentially stacked on the base, and the first cavity is disposed in the support layer.

14. A method of manufacturing a film bulk acoustic resonator, comprising:

providing a temporary substrate;

removing the temporary substrate;

and removing the first sacrificial layer.

15. The method of manufacturing a thin film bulk acoustic resonator according to claim 14, wherein projections of the first electrode lead-out structure and the second electrode lead-out structure on the surface of the piezoelectric layer are shifted from each other.

16. The method of manufacturing a thin film bulk acoustic resonator according to claim 14, wherein a projection of the first gap and the second gap on the piezoelectric layer forms a closed ring shape or a ring shape having a gap.

17. The method of manufacturing a thin film bulk acoustic resonator according to claim 16, wherein the method of forming the first electrode lead-out structure comprises:

forming a first sacrificial bulge on the edge of the first electrode, wherein the first sacrificial bulge is positioned on the first electrode and on the side wall of the first electrode, or the first sacrificial bulge is positioned on the side wall of the first electrode;

forming a first conductive layer overlying the piezoelectric layer and the first sacrificial protrusion;

and patterning the first conductive layer to form the first electrode leading-out structure.

18. The method of manufacturing a thin film bulk acoustic resonator according to claim 16, wherein the method of forming the second electrode lead-out structure comprises:

forming a second sacrificial bulge on the edge of the second electrode, wherein the second sacrificial bulge is positioned on the second electrode and the side wall of the second electrode, or the second sacrificial bulge is positioned on the side wall of the second electrode;

forming a second conductive layer overlying the piezoelectric layer and the second sacrificial protrusion;

and patterning the second conductive layer to form the second electrode leading-out structure.

19. The method for manufacturing a thin film bulk acoustic resonator according to claim 17 or 18, wherein the sacrificial protrusion is removed when the first sacrificial layer is removed;

forming a first release hole penetrating the piezoelectric layer to expose the first sacrificial layer, and removing the first sacrificial layer through the first release hole;

and forming a second release hole penetrating through the electrode lead-out structure to expose the sacrificial protrusion, and removing the sacrificial protrusion through the second release hole.

20. The method for manufacturing a thin film bulk acoustic resonator according to claim 14, further comprising:

forming first protrusions on the first electrode, the first protrusions being distributed along a boundary of the effective resonance region;

when the first electrode leading-out structure is formed by etching, the first bulge is also formed by etching, and the first bulge is made of the same material as the first electrode leading-out structure;

or, the first protrusion is formed after the first electrode lead-out structure is formed;

alternatively, the first protrusion may be formed after the first electrode is formed and before the first electrode lead-out structure.

21. The method as claimed in claim 20, wherein the projection of the first protrusion and the first gap on the surface of the piezoelectric layer form a closed or gapped ring.

22. The method of manufacturing a thin film bulk acoustic resonator according to claim 20, wherein the material of the first bump comprises a dielectric material; alternatively, the first and second electrodes may be,

the material of the first protrusion is the same as that of the first electrode.

23. The method for manufacturing a thin film bulk acoustic resonator according to claim 14, further comprising:

forming second protrusions on the second electrode, the second protrusions being distributed along a boundary of the effective resonance region;

and when the second electrode leading-out structure is formed by etching, the second bulge is also formed by etching, and the material of the second bulge is the same as that of the second electrode leading-out structure.

Or, the second protrusion is formed after the second electrode lead-out structure is formed;

alternatively, the second projection is formed after the second electrode is formed and before the second electrode lead-out structure.

24. The method for manufacturing a thin film bulk acoustic resonator according to claim 23, further comprising: the projections of the second protrusion and the second gap on the surface of the piezoelectric layer form a closed ring or a ring with a gap.

25. The method of manufacturing a thin film bulk acoustic resonator according to claim 24, wherein the material of the second bump comprises a dielectric material; alternatively, the first and second electrodes may be,

the material of the second protrusion is the same as the material of the second electrode.

26. The method for manufacturing a thin film bulk acoustic resonator according to claim 14, further comprising:

after forming the first electrode, forming a first dielectric layer on the piezoelectric layer of the ineffective resonance area, wherein the first dielectric layer is separated from the first electrode, the first dielectric layer is formed between the first substrate and the piezoelectric layer, and the first dielectric layer is continuously connected with the first lapping part;

and after the second electrode is formed, forming a second dielectric layer on the piezoelectric layer of the ineffective resonance area, wherein the second dielectric layer is separated from the second electrode and is continuously connected with the second lapping part.

27. The method of manufacturing a thin film bulk acoustic resonator according to claim 14, wherein the piezoelectric layer is a complete film layer; or, after forming the second electrode lead-out structure, further comprising:

and etching the piezoelectric layer at the edge of the effective resonance area to form an air boundary penetrating through the piezoelectric layer and communicated with the first cavity.

28. The method of manufacturing a thin film bulk acoustic resonator according to claim 27, wherein the air side gap, the first air gap, and the second air gap are offset from each other in projection on the piezoelectric layer and enclose a closed ring shape or a ring shape with a gap.

29. The method for manufacturing a thin film bulk acoustic resonator according to claim 14, further comprising:

forming a cap on the piezoelectric stack, the cap including a second cavity, the second electrode being located within the second cavity.

30. The method of manufacturing a thin film bulk acoustic resonator according to claim 14, wherein the material of the first sacrificial layer includes: phosphosilicate glass, low temperature silica, borophosphosilicate glass, germanium, carbon, polyimide, or photoresist.

31. The method for manufacturing a thin film bulk acoustic resonator according to claim 14, wherein the material of the first sacrificial layer is polyimide or photoresist, and is removed by an ashing method; alternatively, the first and second electrodes may be,

the first sacrificial layer is made of low-temperature silicon dioxide and is removed by hydrofluoric acid solvent.