CN112039469A

CN112039469A - Method for manufacturing film bulk acoustic resonator

Info

Publication number: CN112039469A
Application number: CN202010549480.2A
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 invention discloses a manufacturing method of a film bulk acoustic resonator, which comprises the steps of providing a temporary substrate; forming a piezoelectric layer on a temporary substrate; forming a first sacrificial protrusion on the piezoelectric layer; forming a first electrode including a first electrode resonance portion and a first electrode lead-out portion on the piezoelectric layer and the first sacrificial projection; forming a first substrate including a first cavity on a piezoelectric layer; removing the temporary substrate; forming a second sacrificial protrusion on the piezoelectric layer; forming a second electrode including a second electrode resonance portion and a second electrode lead-out portion located in the effective resonance region on the piezoelectric layer and the second sacrificial projection; the first electrode resonance part and the second electrode resonance part are positioned in the first cavity; and removing the first sacrificial protrusion and the second sacrificial protrusion to form a first gap and a second gap respectively. The invention can achieve the effect of eliminating boundary clutter of an effective resonance area, thereby improving the Q of the resonator.

Description

Method for manufacturing film bulk acoustic resonator

Technical Field

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

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 method for manufacturing a film bulk acoustic resonator, 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 method for manufacturing a film bulk acoustic resonator, including:

providing a temporary substrate;

forming a piezoelectric layer on the temporary substrate;

forming a first sacrificial protrusion on a first surface of the piezoelectric layer at an edge of an effective resonance region;

forming a first electrode on the piezoelectric layer and the first sacrificial protrusion, the first electrode including a first electrode resonance portion located in an effective resonance region and a first electrode lead-out portion extending to an ineffective region as a first signal connection terminal;

forming a first substrate on the piezoelectric layer, wherein a first cavity is formed in the first substrate, the first electrode resonance part is positioned in the first cavity, and the first electrode lead-out part extends to the periphery of the first cavity;

removing the temporary substrate;

forming a second sacrificial protrusion on a second surface of the piezoelectric layer, the second sacrificial protrusion being located at an edge of the effective resonance region;

forming a second electrode on the piezoelectric layer and the second sacrificial protrusion, wherein the second electrode comprises a second electrode resonance part and a second electrode lead-out part which are positioned in an effective resonance area, and the second electrode lead-out part extends to the periphery of the first cavity; 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 the effective resonance region of a resonator;

and removing the first sacrificial protrusion and the second sacrificial protrusion to form a first gap and a second gap respectively.

The invention has the beneficial effects that:

the first electrode comprises a first electrode resonance part and a first electrode leading-out part, the second electrode comprises a second electrode resonance part and a second electrode leading-out part, wherein the first electrode leading-out part and the second electrode leading-out part respectively form a first gap and a second gap in the boundary area of the effective resonance area, and the first gap and the second gap can achieve the effect of eliminating boundary noise waves of the effective resonance area, so that the Q value of the resonator is improved. Through forming the piezoelectric layer on the temporary substrate surface for the piezoelectric layer can form on smooth temporary substrate, guarantees that the piezoelectric layer has better lattice orientation, improves the piezoelectricity characteristic of piezoelectric layer, and then improves the performance of syntonizer. By forming the first electrode on the first surface of the piezoelectric layer and then forming the second electrode on the second surface, the process of patterning the electrodes on the two surfaces of the piezoelectric layer avoids the etching of the piezoelectric layer in the electrode forming process, ensures the integrity and the flatness of the piezoelectric layer, reduces the influence on the piezoelectric layer, and improves the performance of the resonator; and the method is compatible with the resonator main body process, and the flow is simple.

Further, when the piezoelectric layer is a complete film layer, the structural strength of the resonator can be increased; when the piezoelectric layer is provided with the air side gap, the edge of the piezoelectric layer is exposed in the air, so that the transverse wave loss can be inhibited; when the projections of the air 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.

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, and the quality factor of the resonator is improved.

Furthermore, the first dielectric layer and the 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.

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 flowchart illustrating a method for manufacturing a film bulk acoustic resonator according to a first embodiment of the present invention;

2-9 are schematic structural diagrams illustrating steps corresponding to a method for manufacturing a thin film bulk acoustic resonator according to a first embodiment of the present invention;

FIG. 10 is a top view of FIG. 9;

fig. 11 is a schematic structural diagram illustrating a corresponding step of a method for manufacturing a film bulk acoustic resonator according to a second embodiment of the present invention;

fig. 12 to 13 are schematic structural diagrams illustrating steps corresponding to a method for manufacturing a thin film bulk acoustic resonator according to a third embodiment of the present invention;

FIGS. 14 and 15 are top views of two of the raised structures of FIG. 13, respectively;

fig. 16 is a schematic structural diagram illustrating a corresponding step of a method for manufacturing a film bulk acoustic resonator according to a fourth embodiment of the present invention;

fig. 17 to fig. 18 are schematic structural diagrams illustrating steps corresponding to a manufacturing method of a thin film bulk acoustic resonator according to a fifth embodiment of the present invention;

FIG. 19 is a top view of FIG. 18;

fig. 20 to 21 are schematic structural diagrams illustrating steps corresponding to a manufacturing method of a film bulk acoustic resonator according to a sixth embodiment of the present invention;

fig. 22 to 24 respectively show corresponding structural diagrams of the film bulk acoustic resonator with different structures after the top cover is formed.

Description of reference numerals:

100. a first substrate; 101. a support layer; 101', a substrate; 102. a first electrode; 103. a piezoelectric layer; 104. a second electrode; 105. a first electrode resonance section; 106. a first electrode lead-out section; 1061. a first overhead portion; 1062. a first lap joint portion; 107. a second electrode resonance section; 108. a second electrode lead-out section; 1081. a second overhead portion; 1082. a second lap joint portion; 109a, a first sacrificial protrusion; 109b, a second sacrificial protrusion; 110a, a first cavity; 110b, a second cavity; 120a, a first void; 120b, a second void; 121a, a first dielectric layer; 121b, a second dielectric layer; 122a, a first protrusion; 122b, a second protrusion; 123. a first sacrificial layer; 200. a temporary substrate; 210. etching the stop layer; 300. a second substrate; 301. a bonding layer; 303. an air gap.

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, in which a first electrode is configured to include a first electrode resonance portion and a first electrode lead-out portion, a second electrode is configured to include a second electrode resonance portion and a second electrode lap region, and the first electrode lead-out portion and the second electrode lead-out portion respectively form a first gap and a second gap at an edge of an effective resonance region; the first gap and the second gap can achieve the effect of eliminating boundary clutter of the effective resonance area, and further the Q value of the resonator is improved.

The following describes a method for manufacturing a film bulk acoustic resonator according to the present invention 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.

Example one

FIG. 1 is a diagram illustrating the steps of a method of fabricating a film bulk acoustic resonator of the present invention;

referring to fig. 1, a method for manufacturing a thin film bulk acoustic resonator includes:

s01: providing a temporary substrate 200;

s02: forming a piezoelectric layer 103 on a temporary substrate 200;

s03: forming a first sacrificial protrusion 109a on a first surface of the piezoelectric layer 103, the first sacrificial protrusion 109a being located at an edge of the effective resonance region;

s04: forming a first electrode 102 on the piezoelectric layer 103 and the first sacrificial protrusion 109a, the first electrode 102 including a first electrode resonance section 105 and a first electrode lead-out section 106 located in the effective resonance region, the first electrode lead-out section 106 extending to the ineffective region as a first signal connection terminal;

s05: forming a first substrate 100 on the piezoelectric layer 103, wherein a first cavity 110a is formed in the first substrate 100, a first electrode resonance part 105 is located in the first cavity 110a, and a first electrode lead-out part 106 extends to the periphery of the first cavity 110 a;

s06: removing the temporary substrate 200;

s07: forming a second sacrificial protrusion 109b on the second surface of the piezoelectric layer 103, the second sacrificial protrusion 109b being located at an edge of the effective resonance region;

s08: forming a second electrode 104 on the piezoelectric layer 103 and the second sacrificial protrusion 109b, the second electrode 104 including a second electrode resonance portion 107 and a second electrode lead-out portion 108 located in the effective resonance region, the second electrode lead-out portion 108 extending to the periphery of the first cavity 110 a; the region where the first electrode 102, the piezoelectric layer 103, and the second electrode 104 overlap each other in the direction perpendicular to the surface of the piezoelectric layer 103 constitutes an effective resonance region of the resonator;

s09: the first sacrificial protrusion 109a and the second sacrificial protrusion 109b are removed to form a first void 120a and a second void 120b, respectively.

Fig. 2 to 10 are schematic structural diagrams corresponding to corresponding steps of a method for manufacturing a thin film bulk acoustic resonator according to an embodiment, and the method for manufacturing a thin film bulk acoustic resonator according to the embodiment will be described in detail with reference to fig. 2 to 10.

Referring to fig. 2, step S01 is performed to provide a temporary substrate 200;

the temporary substrate 200 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 (Si), silicon germanium (SiGe), indium arsenide (Ins), gallium arsenide (Gs), indium phosphide (InP), or other III/V compound semiconductors, and further includes a multilayer structure composed of these semiconductors, or may be Silicon On Insulator (SOI), silicon on insulator (SSOI), silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI), and germanium on insulator (GeOI), or may be double-Side Polished silicon wafers (Doule Side Polished wafers (DSP), or may be ceramic substrates such as alumina, quartz, glass substrates, or the like. The temporary substrate 200 in this embodiment is a P-type high-resistance monocrystalline silicon wafer with <100> crystal orientation.

It is noted that the surface of the temporary substrate 200 needs to be planarized to ensure the quality of the piezoelectric layer to be formed later.

Referring to fig. 3, step S02 is performed to form the piezoelectric layer 103 on the temporary substrate 200.

Before forming the piezoelectric layer 103, an etch stop layer 210 may be formed on the temporary substrate 200, the etch stop layer 210 being formed between the temporary substrate 200 and the piezoelectric layer 103, and the material thereof includes, but is not limited to, silicon nitride (Si)₃N₄) And silicon oxynitride (SiON); the etching stop layer 210 can be used to increase the structural stability of the finally manufactured film bulk acoustic resonator, and on the other hand, the etching stop layer 210 has a lower etching rate, so that over-etching can be prevented in the process of removing the temporary substrate 200, and the surface of the piezoelectric layer 103 located below the etching stop layer is protected from being damaged, so that the piezoelectric layer 103 always keeps flatness and integrity, and the performance and reliability of the device are improved.

Before the piezoelectric layer 103 is formed, a seed layer (not shown in the figure) can be further formed on the etching stop layer 210, the seed layer is formed between the etching stop layer 210 and the piezoelectric layer 103, and the seed layer has guidance for the crystal directions of the piezoelectric layer 103, the first electrode 102 and the second electrode 104 which are formed subsequently, so that the piezoelectric layer 103 which is formed subsequently can grow along a specific crystal direction, and the uniformity of the piezoelectric layer 103 is ensured; 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.

As a material of the piezoelectric layer 103, aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNO) can be used₃) Quartz (quartz), potassium niobate (KNO)₃) Or lithium tantalate (Lito)₃) And the like, and combinations thereof. When the piezoelectric layer 103 comprises aluminum nitride (AlN), the piezoelectric layer 103 may further comprise a rare earth metal, such as at least one of scandium (S), erbium (Er), yttrium (Y), and lanthanum (La). Further, when the piezoelectric layer 103 includes aluminum nitride (AlN), the piezoelectric layer 103 may further include a transition metal, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). The piezoelectric layer 103 can 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 this embodiment, the piezoelectric layer 103 is formed on the surface of the temporary substrate, so that the piezoelectric layer 103 is a flat film layer, and both the first surface and the second surface of the piezoelectric layer 103 are flat surfaces, cover the first cavity 110a and extend out of the first cavity 110 a. The first surface and the second surface of the piezoelectric layer 103 are both planar, which can make the piezoelectric layer 103 have better lattice orientation, improve the piezoelectric properties of the piezoelectric layer 103, and further improve the overall performance of the resonator.

Referring to fig. 4, step S03 is performed to form a first sacrificial protrusion 109a on the first surface of the piezoelectric layer 103 at an edge of the effective resonance area;

the method of forming the first sacrificial protrusion 109a includes:

forming a first sacrificial raised material layer on a first surface of the piezoelectric layer 103, the first sacrificial raised material layer overlying the piezoelectric layer 103; the first sacrificial protrusion material layer is patterned to form a first sacrificial protrusion 109a outside the edge of the effective resonance region and next to a sidewall of the first electrode resonance portion 105 (formed in a subsequent process).

The first sacrificial protrusion 109a may have a step-like protrusion structure or a column-like structure, and the shape of the first sacrificial protrusion 109a is not limited thereto.

Preferably, the shape of the cross section of the first sacrificial protrusion 109a in the direction perpendicular to the surface of the piezoelectric layer 103 is a trapezoid, and the trapezoid forms an angle of less than 90 degrees with the surface of the piezoelectric layer 103 at a side near the effective resonance region, of course, the shape of the cross section of the first sacrificial protrusion 109a in the direction perpendicular to the surface of the piezoelectric layer 103 may be other shapes, such as a triangle, a rectangle, etc.; the first sacrificial protrusion 109a is formed in a trapezoidal shape in a cross section in a direction perpendicular to the surface of the piezoelectric layer 103, which is more advantageous for eliminating boundary noise and preventing lateral leakage of an acoustic wave.

In this embodiment, the first sacrificial bump material layer comprises phosphosilicate glass, low temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide, or photoresist.

Referring to fig. 5, step S04 is performed to form a first electrode 102 on the piezoelectric layer 103 and the first sacrificial protrusion 109a, the first electrode 102 including a first electrode resonance portion 105 and a first electrode lead-out portion 106 located in the effective resonance region, the first electrode lead-out portion 106 extending to the ineffective region as a first signal connection terminal.

The first electrode 102 extends continuously from the active resonance region to the inactive region, i.e., the first electrode lead-out portion 106 extends from the boundary of the first electrode resonance portion 105 to the outside of the first cavity. In this embodiment, the first electrode lead-out portion 106 covers the first sacrificial protrusion 109a and the surface of the piezoelectric layer 103 of the inactive area.

The method of forming the first electrode 102 includes:

forming a first conductive layer covering the piezoelectric layer 103 and the first sacrificial bump 109 a; the first conductive layer is patterned to form a first electrode 102, the first electrode 102 includes a first electrode resonance part 105 and a first electrode lead-out part 106, and the first electrode lead-out part 106 includes a first overhead part 1061 covering the first sacrificial protrusion 109a and a first bridging part 1062 located on the surface of the piezoelectric layer 103.

The first overhead part 1061 is connected to the first electrode resonator 105, and the first bridging part 1062 extends to the inactive area as a signal connection terminal.

In this embodiment, after forming the first electrode 102, the method further includes: the first sacrificial protrusion 109a is removed to form a first void 120 a. The first air gap 120a can expose the edge of the first electrode resonance portion 105 to the air, and the transverse wave is reflected at the air interface when being transmitted to the edge of the first electrode resonance portion 105, so that the loss of the transverse wave can be effectively suppressed, and the Q value of the resonator can be further improved.

The first electrode lead-out portion 106 includes a first overhead portion 1061 enclosing the first gap 120a, and a first bridging portion 1062 extending to the inactive area as a signal connection terminal. The first bridging part 1062 surrounds the outer periphery of the first electrode resonance part 105, or the first bridging part 1062 is disposed on a part of the outer periphery of the first electrode resonance part 105; the first overhead part 1061 surrounds the outer periphery of the first electrode resonance part 105, or the first overhead part 1061 is disposed at a part of the outer periphery of the first electrode resonance part 105. The first bridging part 1062 may surround the outer circumference of the first electrode resonance part 105, and the first overhead part 1061 may surround the outer circumference of the first electrode resonance part 105. The first overhead part 1061 covers the entire end surface of the first bridging part 1062 facing the first electrode resonance part 105, and the size of the part of the first overhead part 1061 contacting the first electrode resonance part 105 is equal to the size of the end surface of the first bridging part 1062 facing the first electrode resonance part 105. The first bridging part 1062 may be one or more, and the first bridging part 1062 and the first overhead part 1061 may be planar or linear. The first overhead part 1061 covers all or part of the end surface of the first bridging part 1062 facing the first electrode resonance part 105, and the size of the part of the first overhead part 1061 contacting the first electrode resonance part 105 may be larger or smaller than the size of the end surface of the first bridging part 1062 facing the first electrode resonance part 105.

In the present embodiment, the first overhead part 1061 is provided at a part of the outer periphery of the first electrode resonance part 105. In another embodiment, the first overhead part 1061 forms a closed loop around the outer circumference of the first electrode resonance part 105.

In the present embodiment, the first overlapping part 1062 is provided at a partial outer circumference of the first electrode resonance part 105. In another embodiment, the first overlapping part 1062 may form a closed loop around the outer circumference of the first electrode resonance part 105.

In this embodiment, the first overhead part 1061 and the first lap joint 1062 are both continuous surfaces to increase the contact area with the first electrode resonance part 105, which is beneficial to reducing impedance and improving the Q value of the resonator.

Referring to fig. 6, step S05 is performed to form a first substrate 100 on the piezoelectric layer 103, the first substrate 100 having a first cavity 110a formed therein, the first electrode resonance portion 105 located in the first cavity 110a, and the first electrode lead-out portion 106 extending to the periphery of the first cavity 110 a.

In one embodiment, the method of forming the first substrate 100 including the first cavity 110a is as follows:

forming a support layer 101 on the piezoelectric layer 103, and forming a first cavity 110a in the support layer 101;

providing a substrate 101 ', and bonding the substrate 101' on the support layer 101;

the support layer 101 and the base 101' constitute a first substrate 100.

Specifically, in the present embodiment, first, the support layer 101 is formed by a chemical vapor deposition or physical vapor deposition method, the support layer covers the piezoelectric layer 103, the first electrode resonance section 105, and the first electrode lead-out section 106, and the material of the support layer 101 is, for example, silicon dioxide (SiO) or the like₂) Silicon nitride (Si)₃N₄) Alumina (Al 2O)₃) And aluminum nitride.

Then, a first cavity 110a is formed in the support layer 101, the first electrode resonance section 105 being located within the first cavity 110 a; in this embodiment, the first cavity 110a penetrates through the support layer 101, and the substrate 101 'is bonded to the support layer 101, so that the substrate 101' covers the first cavity 110 a.

In this embodiment, the first cavity 110a may be formed by etching the support layer 101 through an etching process; the depth and shape of the first cavity 110a are determined by the depth and shape of the cavity required for the bulk acoustic wave resonator to be manufactured, i.e., the depth of the first cavity 110a can be determined by forming the thickness of the support layer 101. In this embodiment, the bottom surface of the cavity is rectangular, but in other embodiments of the present invention, the bottom surface of the cavity may also be circular, oval, or polygonal other than rectangular, such as pentagonal, hexagonal, etc.

In this embodiment, the bonding between the substrate 101 'and the supporting layer 101 may be achieved by thermocompression bonding, or the bonding between the substrate 101' and the supporting layer 101 may be achieved by Dry film bonding, in which a Dry film (Dry film) is coated on the substrate 101 ', an adhesive pattern is formed by exposure and development or laser, and the substrate 101' and the supporting layer 101 are bonded together by the Dry film (Dry film). The material of the base 101' refers to the material of the temporary substrate 200 mentioned below, and is not described herein again.

In another embodiment, the method of forming the first substrate 100 with the first cavity 110a may further be:

providing a first substrate 100; a first cavity 110a is etched into the first substrate 100, the bottom of the first cavity 110a is spaced from the top of the first substrate 100 (i.e. the first cavity 110a does not penetrate the first substrate 100), and the first substrate 100 is bonded to the piezoelectric layer 103, such that the edge of the first electrode resonance part 105 is located within the boundary of the region surrounded by the first cavity 110 a.

In other embodiments, the support layer 101 may be formed on the substrate 101 ', the support layer 101 is etched to form the first cavity 110a, the support layer 101 is bonded to the piezoelectric layer 103, and the substrate 101' and the support layer 103 form the first substrate 100.

The first substrate 100 including the first cavity 110a is bonded on the piezoelectric layer 103 through a bonding process, so that the piezoelectric layer 103 is prevented from being deformed by pressure in the process of forming the first cavity 110a, and the structural stability of the piezoelectric layer 103 is ensured.

In this embodiment, before bonding the first substrate 100 on the piezoelectric layer 103, the first sacrificial protrusion 109a is released (the first sacrificial protrusion may also be released in a subsequent step, but is not limited thereto), so that a first gap 120a is formed between the first overhead portion 1061 and the edge of the first electrode resonance portion 105 and the surface of the piezoelectric layer 103. The first gap 120a exposes the edge of the first electrode resonance part 105, and the transverse wave is reflected at the air interface when being transmitted to the edge of the first electrode resonance part 105, so that the loss of the transverse wave is suppressed, and the Q value of the resonator is increased.

In this embodiment, a bonding process is used to form the first cavity 110a, so that the first sacrificial protrusion 109a may be released before the first substrate 100 is bonded to the piezoelectric layer 103, and in an embodiment in which the piezoelectric layer 103 is an integral film, it can be avoided to punch a hole in the piezoelectric layer 103 and then release the first sacrificial protrusion 109a in a subsequent step, so as to ensure the integrity of the piezoelectric layer 103, improve the structural strength of the piezoelectric layer 103, and improve the yield of the resonator.

Referring to fig. 7, steps S06 and S07 are performed to remove the temporary substrate 200; a second sacrificial protrusion 109b is formed on the second surface of the piezoelectric layer 103, the second sacrificial protrusion 109b being located at an edge of the effective resonance region.

In this embodiment, the temporary substrate 200 is removed by etching or mechanical polishing.

After the temporary substrate 200 is removed, the bonded film bulk acoustic resonator is turned over, and subsequent processes are performed.

The method of forming the second sacrificial protrusion 109b includes:

forming a second layer of sacrificial raised material on a second surface of the piezoelectric layer 103, the second layer of sacrificial raised material overlying the piezoelectric layer 103; the second sacrificial protrusion material layer is patterned to form a second sacrificial protrusion 109b outside the edge of the effective resonance region and abutting against a sidewall of the second electrode resonance portion 107 (formed in a subsequent process). In this embodiment, the second sacrificial protrusion 109b defines the position of the second void 120b to be formed later, and therefore the second sacrificial protrusion 109b needs to be offset from the first sacrificial protrusion 109 a.

The material and shape of the second sacrificial protrusion 109b are referred to the first sacrificial protrusion 109a, and will not be described herein.

Referring to fig. 8, step S08 is performed to form a second electrode 104 on the piezoelectric layer 103 and the second sacrificial protrusion 109b, the second electrode 104 including a second electrode resonance portion 107 located in the effective resonance region and a second electrode lead-out portion 108, the second electrode lead-out portion 108 extending to the periphery of the first cavity 110 a; the region where the first electrode 102, the piezoelectric layer 103, and the second electrode 104 overlap each other in the direction perpendicular to the surface of the piezoelectric layer 103 constitutes an effective resonance region of the resonator.

The second electrode 104 extends continuously from the effective resonance region to the ineffective region, i.e., the second electrode lead-out portion 108 extends from the boundary of the second electrode resonance portion 107 to the outside of the first cavity 110 a. In the present embodiment, the second electrode lead-out portion 108 covers the second sacrificial protrusion 109b and the surface of the piezoelectric layer 103 of the inactive area.

The method of forming the second electrode 104 includes:

forming a second conductive layer covering the piezoelectric layer 103 and the second sacrificial bump 109 b; the second conductive layer is patterned to form a second electrode 104, the second electrode 104 includes a second electrode resonance portion 107 and a second electrode lead-out portion 108, and the second electrode lead-out portion 108 includes a second aerial portion 1081 covering the second sacrificial protrusion 109b and a second bridging portion 1082 located on the surface of the piezoelectric layer 103.

The second overhead portion 1081 is connected to the second electrode resonance portion 107, and the second overlapping portion 1082 extends to the inactive area as a signal connection terminal.

Referring to fig. 9 and 10, fig. 10 is a top view of the state of fig. 9, and the second sacrificial protrusion 109b is released, so that a second air gap 120b is formed between the second overhead portion 1081 and the edge of the second electrode resonance portion 107 and the surface of the piezoelectric layer 103; the second sacrificial protrusion 109b may also be released in a subsequent step, but is not limited thereto. In this embodiment, the first sacrificial protrusion 109a and the second sacrificial protrusion 109b are selectively released, so that the piezoelectric layer 103 is a complete film layer that is not etched, and the structural strength and yield of the resonator can be increased. The second gap 120b can completely expose the edge of the second electrode resonance portion 107 to the air, and the transverse wave is reflected at the air interface when being transmitted to the edge of the second electrode resonance portion 107, so that the loss of the transverse wave can be effectively suppressed, and the Q value of the resonator can be improved.

Further, referring to fig. 10, the second electrode lead-out portion 108 includes a second overhead portion 1081 enclosing a second gap 120b, and a second overlapping portion 1082 extending to the inactive area as a signal connection end; the second overlapping portion 1082 surrounds the outer circumference of the second electrode resonance portion 107, or the second overlapping portion 1082 is disposed at a portion of the outer circumference of the second electrode resonance portion 107; the second overhead portion 1081 surrounds the outer circumference of the second electrode resonance portion 107, or the second overhead portion 1081 is provided at a part of the outer circumference of the second electrode resonance portion 107.

When one of the first signal connecting end and the second signal connecting end is a signal input end, the other one is a signal output end.

The second bridging portion may surround an outer periphery of the second electrode resonance portion, and the second overhead portion may also surround an outer periphery of the second electrode resonance portion. The second overhead portion covers the entire end surface of the second bridging portion opposite to the second electrode resonance portion, and the size of the portion of the second overhead portion in contact with the second electrode resonance portion is equal to the size of the end surface of the second bridging portion opposite to the second electrode resonance portion. The second overlapping part may be one or more, and the second overlapping part and the second overhead part may be planar or linear. The second overhead portion covers all or part of an end face of the second bridging portion opposite to the second electrode resonance portion, and the size of a portion of the second overhead portion in contact with the second electrode resonance portion may be larger or smaller than the size of the end face of the second bridging portion opposite to the second electrode resonance portion.

In the present embodiment, the second overhead portion 1081 is provided at a part of the outer periphery of the second electrode resonance portion 107. In another embodiment, the second overhead portion 1081 forms a closed loop around the outer periphery of the second electrode resonating portion 107.

In the present embodiment, the second overlapping portion 1082 is provided at a part of the outer circumference of the second electrode resonance portion 107. In another embodiment, the second overlapping portion 1082 may form a closed loop shape around the outer circumference of the second electrode resonance portion 107.

In this embodiment, the second overhead portion 1081 and the second bridging portion 1082 are both continuous planar portions, so as to increase the contact area with the second electrode resonance portion 107, which is beneficial to reducing the impedance and improving the Q value of the resonator.

In this embodiment, projections of the first electrode lead-out portion 106 and the second electrode lead-out portion 108 on the surface of the piezoelectric layer 103 are shifted from each other, so that the coupling effect due to potential floating is prevented from occurring, and the parasitic effect is prevented from occurring. Specifically, the projections of the second land portion 1082 and the first land portion 1062 in the surface direction of the piezoelectric layer 103 are shifted, and the projections of the first land portion 1061 and the second land portion 1081 in the surface direction of the piezoelectric layer 103 are shifted. At this time, the clutter cancellation effect is optimal. Projections of the first and

second gaps

120a and 120b on the piezoelectric layer 103 enclose a closed ring shape or a ring shape with gaps. The first gap 120a and the second gap 120b can respectively expose the edge of the first electrode resonance part 105 and the edge of the second electrode resonance part 107 in the air, so that the effect of eliminating boundary noise of an effective resonance area is achieved, and the Q value of the resonator is further improved.

The first electrode and the second electrode may be made of any suitable conductive material or semiconductor material known in the art, wherein the conductive material may be a metal material having a conductive property, for example, made of one of metals such as molybdenum (Mo), aluminum (Al), copper (Au), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Ar), 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, Si, SiGe, or the like. Preferably, in the present embodiment, the second electrode and the first electrode are made of molybdenum metal (Mo), and the piezoelectric layer is made of aluminum nitride (AlN). The shapes of the second electrode and the first electrode can be the same or different, and the areas of the second electrode and the first electrode can be the same or different. In this embodiment, the second electrode and the first electrode have the same shape and area.

In the embodiment, the first electrode 102 is formed on the first surface of the piezoelectric layer 103, and then the second electrode 104 is formed on the second surface of the piezoelectric layer 103, so that the process of patterning the electrodes on the two surfaces of the piezoelectric layer is performed, etching of the piezoelectric layer 103 in the electrode forming process is avoided, the integrity and the flatness of the piezoelectric layer 103 are ensured, and the influence on the piezoelectric layer 103 is reduced, so that the performance of the resonator is improved.

Example two

Referring to fig. 11, the method for manufacturing a thin film bulk acoustic resonator according to the first embodiment further includes:

after the second electrode 104 is formed (on the basis of fig. 9), the edge area of the effective resonance region may also be etched to form an air boundary 303 that extends through the piezoelectric layer 103 and communicates with the first cavity 110 a.

The transverse wave is effectively suppressed by providing an air boundary 303 penetrating the piezoelectric layer 103 and communicating with the first cavity 110a in the edge area of the effective resonance region so that part of the edge of the piezoelectric layer 103 is exposed to the air. The projection of the air gap 303 on the piezoelectric layer 103 is offset from the projections of the first and second

elevated portions

1061, 1081 on the piezoelectric layer 103, thereby better suppressing transverse waves. The air gaps 303 are formed to have a length and are distributed along the edges of the active resonance area outside the first and second

elevated portions

1061 and 1081.

In this embodiment, the air gap 303 may also serve as a release hole, so that the first sacrificial protrusion 109a may be optionally not released during the fabrication of the first substrate, and the first sacrificial protrusion 109a and the second sacrificial protrusion 109b may be simultaneously released after the formation of the second electrode 104 and the air gap 303.

In other embodiments, the piezoelectric layer 103 can be a complete film layer without etching, and such an arrangement can increase the structural strength of the resonator.

EXAMPLE III

Referring to fig. 12 and 13, the present invention further provides another embodiment, which is different from the first embodiment in that it further includes: forming first projections 122a on the first electrode 102, the first projections 122a being distributed along the boundary of the first electrode resonance portion 105; and/or, a second protrusion 122b is formed on the second electrode 104, and the second protrusion 122b is distributed along the boundary of the second electrode resonance part 107.

Based on fig. 5, after the first electrode 102 is formed, a first protrusion 122a is formed on the first electrode 102, and the first protrusion 122a is distributed along the boundary of the first electrode resonance part and forms a closed or gapped ring shape with the projection of the first gap 120a on the surface of the piezoelectric layer 103.

And or, based on fig. 8, after forming the second electrode 104, forming a second protrusion 122b on the second electrode 104, the second protrusion 122b being distributed along the boundary of the second electrode resonance part 107 and enclosing a closed or gapped ring shape with the projection of the second air gap 120b on the surface of the piezoelectric layer 103. It should be noted that, when the first electrode 102 is formed, the first protrusion 122a may also be formed by etching, or the first protrusion 122a may be formed after the first electrode 102 is formed; similarly, when the second electrode 104 is formed on the second protrusion 122b, the second protrusion 122b may be formed by etching, or the second protrusion 122b may be formed after the second electrode 104 is formed.

In this embodiment, the method of forming the first protrusion 122a is as follows: after forming the first electrode 102, before bonding the first substrate 100:

forming a mask layer (not shown) on the piezoelectric layer 103 and the first electrode 102, the mask layer exposing a partial surface of an edge of the first electrode resonance section 105;

forming a first protrusion material layer covering the mask layer and the exposed first electrode resonance part 105;

the mask layer is removed to form the first protrusion 122 a.

By forming a mask layer on the piezoelectric layer 103 and the first electrode 102, it can be ensured that the piezoelectric layer 103 is not etched, and the integrity of the piezoelectric layer 103 is ensured.

The first protrusion 122a is a continuous whole or includes a plurality of first sub-protrusions arranged intermittently.

The forming method of the second protrusion 122b is similar to the forming method of the first protrusion 122a, and is also formed in a mask layer mode, the mask layer is formed on the piezoelectric layer 103 and the first electrode 102, the mask layer can expose a part of the first electrode 102 at the edge, and then the first protrusion 122a is formed through patterning, so that the piezoelectric layer 103 and the first electrode 102 can be ensured not to be etched, the integrity of the piezoelectric layer 103 and the first electrode 102 is ensured, and the overall structure stability of the formed resonator is further ensured.

The areas where the first protrusion 122a and the second protrusion 122b are located form an acoustic impedance mismatch area, and acoustic impedance mismatch between the boundary of the effective resonance area and the inside of the effective resonance area can be achieved, the first protrusion 122a and the first overhead part 1061 of the first electrode lead-out part 106 can be surrounded into a ring shape, or the second protrusion 122b and the second overhead part 1081 of the second electrode lead-out part 108 can be surrounded into a ring shape, so that the effect of inhibiting transverse clutter leakage is achieved together, and the quality factor of the resonator is further improved.

In this embodiment, when the first protrusion 122a is a continuous whole or when the first protrusion 122a is a continuous whole, the first protrusion 122a and the first overhead part 1061 form a closed ring shape, or when the second protrusion 122b and the second overhead part 1061 form a closed ring shape at the boundary of the effective resonance area, it is more beneficial to prevent the lateral leakage of the sound wave. In other embodiments, only the first protrusion 122a or the second protrusion 122b may be included, and the first protrusion 122a and the first overhead part 1061 form a ring shape, or the second protrusion 122b and the second overhead part 1061 form a ring shape. The pattern enclosed by the first protrusion 122a and the first overhead part 1061, or the second protrusion 122b and the second overhead part 1061 may not be a closed ring.

The projections of the first and

second projections

122a and 122b on the surface of the piezoelectric layer 103 may enclose a closed or an open ring.

Specifically, the first protrusion 122a and the second protrusion 122b may be a continuous whole or include a plurality of sub-protrusions arranged intermittently, and the first protrusion 122a and the second protrusion 122b may form a closed ring or a non-closed ring.

Referring to fig. 14, the case where the projections of the first projection 122a and the second projection 122b on the surface of the piezoelectric layer 103 enclose a closed ring shape may be: when the first protrusion 122a and the second protrusion 122b are a continuous whole, the first protrusion 122a and the second protrusion 122b may form a closed ring shape alone, or the first protrusion 122a and the second protrusion 122b may be arranged oppositely and complementary to form a closed ring shape.

Referring to fig. 15, when the first protrusion 122a and the second protrusion 122b include a plurality of sub-protrusions intermittently provided, the first protrusion 122a and the second protrusion 122b can be complementary to each other, and a closed ring shape can be formed on a projection of the piezoelectric layer 103.

It should be noted that the projection of the first protrusion 122a and the second protrusion 122b on the surface of the piezoelectric layer 103 is not limited to a closed ring shape; the case where the projections of the first projection 122a and the second projection 122b on the surface of the piezoelectric layer 103 enclose an unclosed ring shape may be: when the first protrusion 122a and the second protrusion 122b are both a continuous whole, and the first protrusion 122a and the second protrusion 122b are not overlapped and not complemented with each other, the projection on the piezoelectric layer 103 may form an unclosed ring, and when the first protrusion 122a and the second protrusion 122b are a plurality of discontinuously arranged sub-protrusions and are not complemented with each other, the projection on the surface of the piezoelectric layer 103 of the first protrusion 122a and the projection on the surface of the second protrusion 122b form an unclosed ring, and similarly, the projection on the surface of the piezoelectric layer 103 of the first protrusion 122a and the projection on the surface of the second protrusion 122b form an unclosed ring is not limited thereto.

The material of the first protrusion 122a and the second protrusion 122b may be a conductive material or a dielectric material, and when the material of the first protrusion 122a or the second protrusion 122b is a conductive material, it may be the same as the material of the first electrode 102 or the second electrode 104, and when the material of the first protrusion 122a or the second protrusion 122b is a dielectric material, it may be any one of silicon oxide, silicon nitride, silicon oxynitride, or silicon carbonitride, but is not limited thereto.

In other embodiments, only at least one of the first and

second protrusions

122a and 122b may be included. It is understood that when both the first protrusion 122a and the second protrusion 122b are included, it is more advantageous to prevent lateral leakage of the acoustic wave.

Example four

Referring to fig. 16, the present invention further provides another embodiment, which is different from the first embodiment in that the present invention further includes: further comprising: after the first electrode 102 is formed, a first dielectric layer 121a is formed on the piezoelectric layer 103 in the inactive area, spaced apart from the first electrode resonance section 105; after the second electrode 104 is formed, a second dielectric layer 121b is formed on the piezoelectric layer 103 in the inactive area, spaced apart from the second electrode resonance portion 107 of the second electrode 104.

The specific method comprises the following steps:

based on fig. 5, after the first electrode 102 is formed, a first dielectric layer 121a is formed on the piezoelectric layer 103 in the inactive area, spaced apart from the first electrode resonance portion 105, the first dielectric layer 121a is continuously connected to the first electrode lead-out portion 106, the first dielectric layer 121a is located at the periphery of the active resonance area and forms a gap between the edge of the active resonance area and the edge of the first electrode resonance portion 105, and the first dielectric layer 121a and the first bridging portion 1062 surround the first electrode resonance portion 105; the first dielectric layer 121a and the first bridging portion 1062 are in contact with and complementary to each other on the surface of the piezoelectric layer 103, surround a ring shape on the surface of the piezoelectric layer 103, and extend over the area other than the edge of the effective resonance area. The first dielectric layer 121a 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, based on fig. 8, after forming the second electrode 104, further including:

a second dielectric layer 121b is formed on the piezoelectric layer 103 in the inactive area so as to be spaced apart from the second electrode resonance portion 107, the second dielectric layer 121b is continuously connected to the second electrode lead-out portion 108, the second dielectric layer 121b is located at the periphery of the active resonance area and forms a gap between the edge of the active resonance area and the edge of the second electrode resonance portion 107, and the second dielectric layer 121b and the second overlapping portion 1082 surround the second electrode resonance portion 107. The second dielectric layer 121b and the second bridging portion 1082 meet and complement each other at the surface of the piezoelectric layer 103, surround a ring shape at the surface of the piezoelectric layer 103, and cover the region other than the edge of the effective resonance region. The material of the second dielectric layer 121b refers to the material of the first dielectric layer 121a, and is not described herein again.

In this embodiment, the first dielectric layer 121a and the second dielectric layer 121b are spaced apart from the first electrode resonance portion 105 and the second electrode resonance portion 107 to form a gap therebetween, and the first electrode resonance portion 105 and the second electrode resonance portion 107 are exposed to the air, whereby loss of transverse waves can be effectively suppressed.

The first dielectric layer 121a and the second dielectric layer 121b are respectively formed on the upper surface and the lower surface of the piezoelectric layer 103, so that the bonding effect can be improved when a 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 121a and the second dielectric layer 121 b;

further, the surface of the first dielectric layer 121a is flush with the surface of the first bridging portion 1062, and the surface of the second dielectric layer 121b is flush with the surface of the second bridging portion 1082, so that the mechanical strength is improved, and the bonding effect of the top cover is improved.

EXAMPLE five

Referring to fig. 17 to 19, in another embodiment, based on fig. 5, after the first electrode 102 is formed, a first protrusion 122a and a first dielectric layer 121a may be further formed in sequence, and after the second electrode 104 is formed, a second protrusion 122b and a second dielectric layer 121b may be further formed in sequence.

Specifically, referring to fig. 17, the first protrusion 107a and the first dielectric layer 121a may be formed at the same time or may not be formed at the same time, and when the materials of the first protrusion 107a and the first dielectric layer 121a are the same, the first protrusion 107a and the first dielectric layer 121a may be formed at the same time;

also, referring to fig. 18, the second protrusion 107b and the second dielectric layer 121b may be formed simultaneously or not, and when the materials of the second protrusion 107b and the second dielectric layer 121b are the same, they may be formed simultaneously.

Fig. 19 shows a top view of fig. 18. referring to fig. 19, this embodiment includes both first protrusion 107a, second protrusion 107b, first dielectric layer 121a, and second dielectric layer 121 b.

It is understood that when the first protrusion 122a, the second protrusion 107b, the first dielectric layer 121a, and the second dielectric layer 121b are included at the same time, it is more advantageous to suppress the leakage of the transverse wave, to improve the mechanical strength, and to improve the effect of the top cap bonding.

In other embodiments, only one of the first protrusion 122a and the second protrusion 122b and at least one of the first dielectric layer 121a and the second dielectric layer 121b may be formed, which is not described herein again.

EXAMPLE six

In other embodiments of the present invention, based on fig. 9, forming a top cover on the piezoelectric layer 103, the top cover including a second cavity 110b, the second electrode resonance part 107 being located in the second cavity 110 b.

In one embodiment, a method of forming a cap includes:

providing a second substrate 300;

forming a bonding layer 301 over a second substrate 300;

patterning the bonding layer 301 to form a second cavity 110 b;

bonding the bonding layer 301 to the piezoelectric layer 103;

referring to fig. 20, a second substrate 300 is provided, and a bonding layer 301 is formed over the second substrate 300; the material 300 of the second substrate refers to the temporary substrate 200, the material of the bonding layer 301 is the same as that of the support layer 101, and the connection method between the second substrate 300 and the bonding layer 301 is the same as that between the base 101' and the support layer 101, and thus the description thereof is omitted.

Patterning the bonding layer 301 to form a second cavity 110 b;

referring to fig. 21, a bonding layer 301 is bonded to the piezoelectric layer; the step of forming the second cavity 110b is the same as the above-mentioned method of forming the first cavity 110a, and is not described herein again. The top cover is formed on the piezoelectric layer 103 through a bonding process, so that each layer exposed in the upper space is prevented from being polluted by the external environment, and meanwhile, the piezoelectric layer on the first cavity 110a can be prevented from being deformed by pressure, and the quality of the resonator is further ensured. Therefore, the top cover is preferably formed by bonding in the present embodiment.

The scheme of adding the top cover is also applicable to the manufacturing methods of the thin film bulk acoustic resonators of the second to fifth embodiments, and fig. 22 to 24 are cross-sectional views of the thin film bulk acoustic resonators of the second to fifth embodiments after adding the top cover.

Specifically, referring to fig. 22, in another embodiment, in an embodiment where the top cover is formed with any one of the above-described methods, at least one of the first protrusion 122a and the second protrusion 122b is formed. An acoustic impedance mismatch region is formed in a region where the first protrusion 122a and/or the second protrusion 122b are/is located to reflect energy diffused outward in the effective resonance region back into the effective resonance region, thereby suppressing leakage of the shear wave.

When the first protrusion 122a and the second protrusion 122b are included at the same time, it is possible to more advantageously suppress the leakage of the lateral noise and reduce the energy loss.

Referring to fig. 23, in an embodiment in which the cap is formed with any one of the above-described methods, at least one of the first dielectric layer 121a and the second dielectric layer 121b may be formed. When the first dielectric layer 121a and the second dielectric layer 121b are included at the same time, it is possible to more advantageously suppress leakage of transverse waves, improve mechanical strength, and improve the effect of top cap bonding.

Referring to fig. 24, in a further embodiment, in the cap embodiment formed by any one of the above-described methods, at least one of the first dielectric layer 121a and the second dielectric layer 121b, and at least one of the first protrusion 122a and the second protrusion 122b may also be formed as well.

When the first protrusion 122a, the second protrusion 122b, the first dielectric layer 121a, and the second dielectric layer 121b are included at the same time, it is more advantageous to suppress the lateral noise leakage, reduce the energy loss, improve the mechanical strength, and improve the effect of the top cap bonding

In summary, the first electrode 102 includes the first electrode resonance portion 105, the first electrode lead-out portion 106, and the second electrode 104 includes the second electrode resonance portion 107 and the second electrode lead-out portion 108, the first electrode lead-out portion 106 and the second electrode lead-out portion 108 respectively form the first gap 120a and the second gap 120b in the boundary area of the effective resonance area, and the first gap 120a and the second gap 120b can achieve the effect of eliminating boundary noise in the effective resonance area, so as to improve the Q value of the resonator.

Through forming the piezoelectric layer on the temporary substrate surface for the piezoelectric layer can form on smooth temporary substrate, guarantees that the piezoelectric layer has better lattice orientation, improves the piezoelectricity characteristic of piezoelectric layer, and then improves the performance of syntonizer. By forming the first electrode on the first surface of the piezoelectric layer and then forming the second electrode on the second surface, the process of patterning the electrodes on the two surfaces of the piezoelectric layer avoids the etching of the piezoelectric layer in the electrode forming process, ensures the integrity and the flatness of the piezoelectric layer, reduces the influence on the piezoelectric layer, and improves the performance of the resonator; and the method is compatible with the resonator main body process, and the flow is simple.

Further, when the piezoelectric layer is a complete film layer, the structural strength of the resonator can be increased; when the piezoelectric layer is provided with air gaps so that the edges of the piezoelectric layer are exposed to air, the loss of transverse waves can be suppressed.

Furthermore, a first protrusion 122a is arranged on the surface of the first electrode 102 and/or a second protrusion 122b is arranged on the surface of the second electrode 104, an acoustic impedance mismatch area is formed in an area where the first protrusion 122a and the second protrusion 122b are located, acoustic impedance mismatch between the boundary of the effective resonance area and the inside of the effective resonance area can be achieved, the projection of the first protrusion 122a and the first overhead part 1061 on the surface of the piezoelectric layer 103 is a closed or open ring or the projection of the second protrusion 122b and the second overhead part 1081 on the surface of the piezoelectric layer 103 is a closed or open ring, so that the effect of inhibiting lateral clutter leakage can be achieved together, and the quality factor of the resonator is further improved;

further, the first dielectric layer 121a and the second dielectric layer 121b are respectively formed on the upper surface and the lower surface of the piezoelectric layer 103, so that the bonding effect can be improved when the top cover is formed later, and the mechanical strength of the whole resonator can be improved due to the arrangement of the first dielectric layer 121a and the second dielectric layer 121 b.

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 method of manufacturing a film bulk acoustic resonator, comprising:

providing a temporary substrate;

forming a piezoelectric layer on the temporary substrate;

forming a first sacrificial protrusion on a first surface of the piezoelectric layer, the first sacrificial protrusion being located at an edge of an effective resonance region;

removing the temporary substrate;

2. The method according to claim 1, wherein the projections of the first electrode lead-out portion and the second electrode lead-out portion on the surface of the piezoelectric layer are shifted from each other.

3. The method as claimed in claim 1, wherein the projection of the first and second gaps on the piezoelectric layer forms a closed ring or a ring with gaps.

4. The method of claim 1, wherein the first electrode lead-out portion includes a first overhead portion surrounding the first gap, and a first land portion extending to the inactive area as a signal connection end, the first land portion surrounding an outer periphery of the first electrode resonance portion, or the first land portion being disposed at a portion of the outer periphery of the first electrode resonance portion; the first overhead portion surrounds the outer periphery of the first electrode resonance portion, or the first overhead portion is disposed at a part of the outer periphery of the first electrode resonance portion.

5. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the second electrode lead-out portion includes a second overhead portion surrounding the second gap, and a second land portion extending to the inactive area as a signal connection terminal; the second lapping part surrounds the periphery of the second electrode resonance part, or the second lapping part is arranged on part of the periphery of the second electrode resonance part; the second overhead portion surrounds the outer periphery of the second electrode resonance portion, or the second overhead portion is provided to a part of the outer periphery of the second electrode resonance portion.

6. The method of claim 1, wherein the step of forming the first electrode comprises:

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

and patterning the first conductive layer to form the first electrode.

7. The method of claim 1, wherein the step of forming the second electrode comprises:

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

and patterning the second conductive layer to form the second electrode.

8. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, further comprising:

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

the method of forming the first bump includes:

when the first electrode is formed by etching, the first protrusion is also formed by etching, and the material of the first protrusion is the same as that of the first electrode;

alternatively, the first protrusion is formed after the first electrode is formed.

9. The method according to claim 8, wherein the first protrusion and the projection of the first gap on the surface of the piezoelectric layer form a closed ring or a ring with a gap.

10. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, further comprising:

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

when the second electrode is formed by etching, the second protrusion is also formed by etching, and the material of the second protrusion is the same as that of the second electrode;

alternatively, the second protrusion is formed after the second electrode is formed.

11. The method of manufacturing a thin film bulk acoustic resonator according to claim 10, wherein the second protrusion and the projection of the second gap on the surface of the piezoelectric layer form a closed ring or a ring with a gap.

12. The method of manufacturing a thin film bulk acoustic resonator according to any one of claims 8 or 9, wherein the first projections include 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.

13. The method of manufacturing a thin film bulk acoustic resonator according to any one of claims 10 or 11, wherein the material of the second bump includes a dielectric material; alternatively, the material of the second protrusion is the same as the material of the second electrode.

14. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, further comprising:

after a first electrode is formed, a first dielectric layer is formed on the piezoelectric layer of the invalid area and is separated from the resonance part of the first electrode, and the first dielectric layer is continuously connected with the leading-out part of the first electrode;

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

15. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, further comprising, before or after forming the second electrode:

etching the edge area of the effective resonance area to form an air edge gap which penetrates through the piezoelectric layer and is communicated with the first cavity, wherein the projection of the air edge gap on the piezoelectric layer is mutually staggered with the projections of the first overhead part and the second overhead part on the piezoelectric layer.

16. The method of claim 1, wherein removing the first sacrificial protrusion and the second sacrificial protrusion comprises:

releasing the first sacrificial protrusion prior to forming the first substrate;

releasing the second sacrificial projection after forming the second electrode lead-out portion;

alternatively, the first and second electrodes may be,

after forming the second electrode lead-out portion, an air boundary penetrating the piezoelectric layer is formed while releasing the first sacrificial projection and the second sacrificial projection.

17. The method as claimed in any one of claims 1 or 16, wherein the material of the first sacrificial bump and the second sacrificial bump comprises phosphosilicate glass, low temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide or photoresist.

18. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein forming a first substrate including a first cavity on the piezoelectric layer comprises:

providing a first substrate;

forming the first cavity in the first substrate;

bonding the first substrate on the piezoelectric layer;

alternatively, the first and second electrodes may be,

forming a support layer on the piezoelectric layer;

forming the first cavity in the support layer;

providing a substrate, and bonding the substrate on the support layer;

the support layer and the base constitute the first substrate.

19. The method for manufacturing a thin film bulk acoustic resonator according to claim 1, further comprising, after forming the second electrode:

and forming a top cover on the piezoelectric layer, wherein the top cover comprises a second cavity, and the second electrode resonance part is positioned in the boundary of the area enclosed by the second cavity.

20. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the first surface and the second surface of the piezoelectric layer are both planar, cover the first cavity, and extend out of the first cavity.