CN112039469B

CN112039469B - Method for manufacturing film bulk acoustic resonator

Info

Publication number: CN112039469B
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
Filing date: 2020-06-16
Publication date: 2024-07-02
Anticipated expiration: 2040-06-16

Abstract

The invention discloses a manufacturing method of a film bulk acoustic resonator, comprising the steps of providing a temporary substrate; forming a piezoelectric layer on a temporary substrate; forming a first sacrificial bump 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 protrusion; forming a first substrate including a first cavity on the 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 portion located in the effective resonance region on the piezoelectric layer and the second sacrificial protrusion; the first electrode resonance part and the second electrode resonance part are positioned in the first cavity; the first sacrificial protrusion and the second sacrificial protrusion are removed to form a first void and a second void, respectively. The invention can achieve the effect of eliminating the boundary clutter of the 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 beginning of the last 90 th generation, rf front-end modules have gradually become the core components of communication devices. Among all the radio frequency front end modules, the filter has become the most powerful component of growth and development prospect. With the rapid development of wireless communication technology, the 5G communication protocol is mature, and the market also puts forward more strict standards on the performance of the radio frequency filter in all aspects. The performance of the filter is determined by the resonator elements that make up the filter. Among the existing filters, a 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 antistatic impact capability.

In general, a thin film bulk acoustic resonator includes two thin film electrodes, and a piezoelectric thin film layer is disposed between the two thin film electrodes, and the working principle of the thin film bulk acoustic resonator is that the piezoelectric thin film layer is utilized to generate vibration under an alternating electric field, the vibration excites bulk acoustic waves propagating along the thickness direction of the piezoelectric thin film layer, and the acoustic waves are transmitted to the interface between the upper electrode and the lower electrode and air to be reflected back, and then are reflected back and forth inside the thin film to form oscillation. Standing wave oscillation is formed when the acoustic wave propagates in the piezoelectric film layer just an odd multiple of half the wavelength.

However, the quality factor (Q) of the cavity type thin film bulk acoustic resonator manufactured at present cannot be further improved, so that the requirement of a high-performance radio frequency system cannot be met.

Disclosure of Invention

The invention aims to provide a manufacturing method of 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 thin film bulk acoustic resonator, including:

Providing a temporary substrate;

Forming a piezoelectric layer on the temporary substrate;

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

Forming a first electrode on the piezoelectric layer and the first sacrificial protrusion, wherein the first electrode comprises a first electrode resonance part and a first electrode extraction part which are positioned in an effective resonance area, and the first electrode extraction part extends to an ineffective area to serve as a first signal connection end;

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 resonant area;

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 extraction part which are positioned in an effective resonance area, and the second electrode extraction part extends to the periphery of the first cavity; the first electrode, the piezoelectric layer and the second electrode form the effective resonance area of the resonator in a region overlapping each other in a direction perpendicular to the surface of the piezoelectric layer;

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 lead-out part, and the second electrode comprises a second electrode resonance part and a second electrode lead-out part, wherein the first electrode lead-out part and the second electrode lead-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 clutter of the effective resonance area, so that the Q value of the resonator is improved. By forming the piezoelectric layer on the surface of the temporary substrate, the piezoelectric layer can be formed on the flat temporary substrate, so that the piezoelectric layer is ensured to have better lattice orientation, the piezoelectric property of the piezoelectric layer is improved, and the performance of the resonator is further improved. The first electrode is formed on the first surface of the piezoelectric layer, and the second electrode is formed on the second surface, so that the electrode patterning process is carried out on the two sides of the piezoelectric layer, the etching of the piezoelectric layer in the electrode forming process is avoided, the integrity and 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 main process of the resonator, and the flow is simple.

Further, when the piezoelectric layer is a complete membrane layer, the structural strength of the resonator can be increased; when the piezoelectric layer is provided with an air side gap, the edge of the piezoelectric layer is exposed in the air, so that the transverse wave loss can be restrained; when the projections of the air side gap, the first gap and the second gap on the piezoelectric layer are staggered, and the air side gap, the first gap and the second gap enclose a closed ring shape, the transverse wave loss can be well restrained.

Further, the first bulge is arranged on the surface of the first electrode and/or the second bulge is arranged on the surface of the second electrode, and the acoustic impedance mismatch area is formed in the area where the first bulge and the second bulge are located, so that acoustic impedance mismatch can be carried out between the boundary of the effective resonance area and the inside of the effective resonance area, and the quality factor of the resonator is improved.

Further, the first dielectric layer and the second dielectric layer are formed on the upper surface and the lower surface of the piezoelectric layer respectively, so that the bonding effect can be improved when the top cover is formed later, 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 invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a flowchart of a method for manufacturing a thin film bulk acoustic resonator according to a first embodiment of the present invention;

fig. 2 to fig. 9 are schematic structural diagrams showing 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 showing steps corresponding to a method for manufacturing a thin film bulk acoustic resonator according to a second embodiment of the present invention;

Fig. 12 to 13 are schematic structural views showing 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 the two raised structures of FIG. 13, respectively;

Fig. 16 is a schematic structural diagram showing steps corresponding to a method for manufacturing a thin film bulk acoustic resonator according to a fourth embodiment of the present invention;

Fig. 17 to 18 are schematic structural diagrams showing steps corresponding to a method for manufacturing 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 views showing steps corresponding to a method for manufacturing a thin film bulk acoustic resonator according to a sixth embodiment of the present invention;

fig. 22 to 24 respectively show schematic structural diagrams of thin film bulk acoustic resonators with different structures after forming a top cover.

Reference numerals illustrate:

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 portion; 106. a first electrode lead-out portion; 1061. a first overhead section; 1062. a first lap joint; 107. a second electrode resonance part; 108. a second electrode lead-out portion; 1081. a second overhead section; 1082. a second lap joint; 109a, first sacrificial projections; 109b, second sacrificial projections; 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, first protrusions; 122b, a second protrusion; 123. a first sacrificial layer; 200. a temporary substrate; 210. an etch stop layer; 300. a second substrate; 301. a bonding layer; 303. an air gap.

Detailed Description

The cavity type film bulk acoustic resonator manufactured at present 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 requirements of a high-performance radio frequency system cannot be met.

In order to solve the above problems, the present invention provides a thin film bulk acoustic resonator, in which a first electrode is provided to include a first electrode resonating section and a first electrode lead-out section, a second electrode is provided to include a second electrode resonating section and a second electrode overlap region, and the first electrode lead-out section and the second electrode lead-out section form a first gap and a second gap at edges of an effective resonating region, respectively; the first gap and the second gap can achieve the effect of eliminating boundary clutter in an effective resonance area, and then the Q value of the resonator is improved.

The method for manufacturing the film bulk acoustic resonator according to the present invention is described in further detail below with reference to the accompanying drawings and specific examples. The advantages and features of the present invention will become more apparent from the following description and drawings, however, it should be understood that the inventive concept may be embodied in many different forms and is not limited to the specific embodiments set forth herein. The drawings are in a very simplified form and are to non-precise scale, merely for convenience and clarity in aiding in the description of 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 a method described herein comprises a series of steps, and the order of the steps presented herein is not necessarily the only order in which the 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. If a component in one drawing is identical to a component in another drawing, the component will be easily recognized in all drawings, but in order to make the description of the drawings clearer, the specification does not refer to all the identical components in each drawing.

Example 1

FIG. 1 is a step diagram of a method of fabricating a thin 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 the 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 resonating section 105 and a first electrode lead-out section 106 located in an effective resonating region, the first electrode lead-out section 106 extending to an ineffective region as a first signal connection terminal;

S05: forming 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 being located within the first cavity 110a, the first electrode lead-out portion 106 extending 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 resonating section 107 and a second electrode lead-out section 108 located in the effective resonating region, the second electrode lead-out section 108 extending to the periphery of the first cavity 110 a; the areas 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 constitute the effective resonance area of the resonator;

S09: the first sacrificial protrusion 109a and the second sacrificial protrusion 109b are removed, forming a first void 120a and a second void 120b, respectively.

Fig. 2 to 10 are schematic structural diagrams corresponding to the steps of a method for fabricating a thin film bulk acoustic resonator according to the first embodiment, and the method for fabricating a thin film bulk acoustic resonator according to the first 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;

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 carbon (SiGe), indium arsenide (Ins), gallium arsenide (Gs), indium phosphide (InP), or other III/V compound semiconductors, and also include multilayer structures composed of these semiconductors, or are silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator (S-SiGeOI), silicon-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), or may be double-sided polished silicon wafers (Doule Side Polished Wfers, DSP), or may be ceramic substrates such as aluminum oxide, quartz, or glass substrates, or the like. The temporary substrate 200 in this embodiment is a P-type high-resistance monocrystalline silicon wafer with a <100> crystal orientation.

It should be noted that the surface of the temporary substrate 200 needs to achieve a certain flatness 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, the materials including, but not limited to, silicon nitride (Si ₃N₄) and silicon oxynitride (SiON); the etch stop layer 210 may be used to increase structural stability of the finally manufactured thin film bulk acoustic resonator on the one hand, and the etch stop layer 210 has a lower etching rate, may prevent over etching during the process of removing the temporary substrate 200, and protect the surface of the piezoelectric layer 103 located thereunder from damage, so that the piezoelectric layer 103 always maintains flatness and integrity, thereby improving device performance and reliability.

Before forming the piezoelectric layer 103, a seed layer (not shown in the figure) may be formed on the etching stop layer 210, where the seed layer is formed between the etching stop layer 210 and the piezoelectric layer 103, and has a direction to the crystal directions of the subsequently formed piezoelectric layer 103, the first electrode 102 and the second electrode 104, so that the subsequently formed piezoelectric layer 103 can be grown along a specific crystal direction, and uniformity of the piezoelectric layer 103 is ensured; the seed layer may be made of aluminum nitride (AlN), and may be formed of a metal or a dielectric material having a hexagonal close-packed (HCP) structure other than AlN. For example, the seed layer may also be formed of metallic titanium (Ti).

As a material of the piezoelectric layer 103, a piezoelectric material having a wurtzite crystal structure such as aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNO ₃), quartz (Qurtz), potassium niobate (KNO ₃), or lithium tantalate (LiTO ₃), or a combination thereof can be used. When the piezoelectric layer 103 includes aluminum nitride (AlN), the piezoelectric layer 103 may further include at least one of rare earth metals such as scandium (S), erbium (Er), yttrium (Y), and lanthanum (La). In addition, when the piezoelectric layer 103 includes aluminum nitride (AlN), the piezoelectric layer 103 may further include at least one of transition metals such as zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). The piezoelectric layer 103 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 this embodiment, the piezoelectric layer 103 is formed on the temporary substrate surface, so the piezoelectric layer 103 is a flat film layer, and the first surface and the second surface of the piezoelectric layer 103 are both 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, so that the piezoelectric layer 103 has better lattice orientation, the piezoelectric property of the piezoelectric layer 103 is improved, and the overall performance of the resonator is further improved.

Referring to fig. 4, step S03 is performed in which a first sacrificial protrusion 109a is formed on the first surface of the piezoelectric layer 103 at the edge of the effective resonance region;

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

Forming a first sacrificial raised material layer on the first surface of the piezoelectric layer 103, the first sacrificial raised material layer covering the piezoelectric layer 103; the first sacrificial bump material layer is patterned to form first sacrificial bumps 109a outside the edges of the active resonance region and immediately adjacent to the sidewalls of the first electrode resonance portion 105 (formed in a subsequent process).

The first sacrificial protrusion 109a may have a stepped protrusion structure or a columnar 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 along the direction perpendicular to the surface of the piezoelectric layer 103 is a trapezoid, and the included angle formed by the trapezoid and the surface of the piezoelectric layer 103 at the side close to the effective resonance area is smaller than 90 degrees, however, the shape of the cross section of the first sacrificial protrusion 109a along the direction perpendicular to the surface of the piezoelectric layer 103 may be other shapes, such as triangle, rectangle, etc.; the first sacrificial protrusion 109a is formed in a trapezoid shape in a cross section perpendicular to the surface of the piezoelectric layer 103, which is more advantageous in eliminating boundary clutter and preventing lateral leakage of acoustic waves.

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

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

The first electrode 102 extends continuously from the effective resonance region to the ineffective 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 in the inactive region.

The method of forming the first electrode 102 includes:

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

The first overhead part 1061 is connected to the first electrode resonance part 105, and the first overlap 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 120a. The first gap 120a can expose the edge of the first electrode resonance portion 105 to air, and when a transverse wave is transmitted to the edge of the first electrode resonance portion 105, reflection occurs at an air interface, so that 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 surrounding the first space 120a, and a first lap portion 1062 extending to the inactive area as a signal connection terminal. The first overlap portion 1062 surrounds the outer periphery of the first electrode resonance portion 105, or the first overlap portion 1062 is disposed at a portion of the outer periphery of the first electrode resonance portion 105; the first overhead part 1061 surrounds the outer circumference of the first electrode resonance part 105, or the first overhead part 1061 is disposed at a portion of the outer circumference of the first electrode resonance part 105. The first overlap portion 1062 may surround the outer periphery of the first electrode resonance portion 105, and the first overhead portion 1061 may surround the outer periphery of the first electrode resonance portion 105. The first overhead part 1061 covers the entire end face of the first overlap part 1062 facing the first electrode resonance part 105, and the size of the portion of the first overhead part 1061 that meets the first electrode resonance part 105 is equal to the size of the end face of the first overlap part 1062 facing the first electrode resonance part 105. The first overlap portion 1062 may be one or more, and the first overlap portion 1062 and the first overhead portion 1061 may be planar or linear. The first overhead part 1061 covers all or part of the end surface of the first overlap part 1062 opposite to the first electrode resonance part 105, and the size of the portion of the first overhead part 1061 that meets the first electrode resonance part 105 may be larger or smaller than the size of the end surface of the first overlap part 1062 opposite to 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 overlap portion 1062 is provided at a part of the outer periphery of the first electrode resonance portion 105. In another embodiment, the first overlap portion 1062 may form a closed loop around the outer circumference of the first electrode resonance portion 105.

In this embodiment, the first overhead portion 1061 and the first overlap portion 1062 are continuous, so as to increase the contact area with the first electrode resonance portion 105, which is beneficial to reducing the impedance and improving the Q value of the resonator.

Referring to fig. 6, step S05 is performed in which the first substrate 100 is formed on the piezoelectric layer 103, the first cavity 110a is formed in the first substrate 100, the first electrode resonance portion 105 is located within the first cavity 110a, and the first electrode lead-out portion 106 extends 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, forming a first cavity 110a in the support layer 101;

providing a substrate 101', 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 chemical vapor deposition or physical vapor deposition, and covers the piezoelectric layer 103, the first electrode resonance portion 105, and the first electrode lead-out portion 106, and the material of the support layer 101 is, for example, one or a combination of several of silicon dioxide (SiO ₂), silicon nitride (Si ₃N₄), aluminum oxide (Al 2O ₃), and aluminum nitride.

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

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 both dependent on the depth and shape of the cavity required for the bulk acoustic 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 the present embodiment, the bottom surface of the cavity is rectangular, but in other embodiments of the present invention, the bottom surface of the cavity may be circular, elliptical, 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 thermal compression bonding, or bonding between the substrate 101' and the supporting layer 101 may be achieved by Dry film bonding, in which Dry film is applied to the substrate 101', and an adhesive pattern is formed by exposing and developing or laser, and the substrate 101' and the supporting layer 101 are bonded together by Dry film. The material of the base 101' refers to the material of the temporary substrate 200 mentioned below, and will not be described here.

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

Providing a first substrate 100; the first cavity 110a is etched in the first substrate 100, where a certain distance is provided between the bottom of the first cavity 110a and the top of the first substrate 100 (i.e., the first cavity 110a does not penetrate through the first substrate 100), and the first substrate 100 is bonded on the piezoelectric layer 103, so that the edge of the first electrode resonance portion 105 is located within the boundary of the surrounding area of 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 to the piezoelectric layer 103 through a bonding process, so that the piezoelectric layer 103 is ensured not to be deformed by compression in the process of forming the first cavity 110a, and the structural stability of the piezoelectric layer 103 is ensured.

In the present embodiment, before the first substrate 100 is bonded to the piezoelectric layer 103, the first sacrificial protrusion 109a is released (the first sacrificial protrusion may be released in a subsequent step, not limited thereto), so that the first air 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 portion 105, and when a transverse wave is transmitted to the edge of the first electrode resonance portion 105, the transverse wave is reflected at the air interface, so that loss of the transverse wave is suppressed, and the Q value of the resonator is further improved.

In this embodiment, the bonding process is adopted to form the first cavity 110a, so that the first substrate 100 is bonded before the piezoelectric layer 103, and the first sacrificial protrusion 109a can be released first, and in the embodiment in which the piezoelectric layer 103 is a complete film layer, the situation that holes are punched in the piezoelectric layer 103 and then the first sacrificial protrusion 109a is released in a subsequent step can be avoided, the integrity of the piezoelectric layer 103 is ensured, the structural strength of the piezoelectric layer 103 is improved, and the yield of the resonator is improved.

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

The temporary substrate 200 is removed by etching or mechanical polishing in this embodiment.

After the temporary substrate 200 is removed, the bonded thin film bulk acoustic resonator is flipped over, and a subsequent process is performed.

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

Forming a second sacrificial raised material layer on the second surface of the piezoelectric layer 103, the second sacrificial raised material layer covering the piezoelectric layer 103; the second sacrificial bump material layer is patterned to form second sacrificial bumps 109b outside the edges of the active resonance region and immediately adjacent to the sidewalls 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 thus 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 formed with reference to the first sacrificial protrusion 109a, and will not be described here.

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 resonating section 107 and a second electrode lead-out section 108 located in the effective resonating region, the second electrode lead-out section 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, that is, 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 110a. In the present embodiment, the second electrode lead-out portion 108 covers the second sacrificial protrusion 109b and the piezoelectric layer 103 surface of the ineffective region.

The method of forming the second electrode 104 includes:

Forming a second conductive layer covering the piezoelectric layer 103 and the second sacrificial protrusion 109b; 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 overhead portion 1081 covering the second sacrificial protrusion 109b and a second overlap portion 1082 located at the surface of the piezoelectric layer 103.

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

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

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

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

The second lap joint part can encircle the outer periphery of the second electrode resonance part, and the second overhead part can encircle the outer periphery of the second electrode resonance part. The second overhead part covers the whole of the end face of the second overlap part opposite to the second electrode resonance part, and the size of the part of the second overhead part, which is connected with the second electrode resonance part, is equal to the size of the end face of the second overlap part opposite to the second electrode resonance part. The second overlap portion may be one or more, and the second overlap portion and the second overhead portion may be planar or linear. The second overhead portion covers all or part of an end face of the second overlap portion opposite to the second electrode resonance portion, and a size of a portion of the second overhead portion that meets the second electrode resonance portion may be larger or smaller than a size of an end face of the second overlap portion opposite to the second electrode resonance portion.

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

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

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

In this embodiment, the 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 offset from each other, so that the coupling effect due to the floating of the potential is prevented from being generated, and the parasitic effect is prevented. Specifically, the projections of the second overlap portion 1082 and the first overlap portion 1062 in the surface direction of the piezoelectric layer 103 are offset, and the projections of the first overhead portion 1061 and the second overhead portion 1081 in the surface direction of the piezoelectric layer 103 are offset. At this time, the clutter cancellation effect is optimal. The projections of the first and second gaps 120a, 120b on the piezoelectric layer 103 enclose a closed ring shape or a ring shape with gaps. The first and second gaps 120a and 120b can expose the edges of the first and second electrode resonance portions 105 and 107 to air, respectively, to achieve the effect of eliminating boundary clutter in the effective resonance region, thereby improving the Q value of the resonator.

The first electrode and the second electrode may use any suitable conductive material or semiconductor material known in the art, where the conductive material may be a metal material having conductive properties, for example, 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 laminate formed of the above metals, and the semiconductor material is Si, ge, siGe, si, siGe or the like. Preferably, in the present embodiment, the second electrode and the first electrode are made of molybdenum (Mo), and the piezoelectric layer is made of aluminum nitride (AlN). The shapes of the second electrode and the first electrode may be the same or different, and the areas of the second electrode and the first electrode may be the same or different. In this embodiment, the second electrode and the first electrode have the same shape and area.

In this 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 electrode patterning process is performed on both sides of the piezoelectric layer, the etching of the piezoelectric layer 103 in the electrode forming process is avoided, the integrity and flatness of the piezoelectric layer 103 are ensured, the influence on the piezoelectric layer 103 is reduced, and therefore, the performance of the resonator is improved.

Example two

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

After forming the second electrode 104 (on the basis of fig. 9), the edge region of the effective resonance region may also be etched to form an air gap 303 that penetrates the piezoelectric layer 103 and communicates with the first cavity 110 a.

The air side gap 303 penetrating the piezoelectric layer 103 and communicating with the first cavity 110a is provided at the edge region of the effective resonance region, so that part of the edge of the piezoelectric layer 103 is exposed to air, thereby effectively suppressing transverse waves. The projection of the air gap 303 on the piezoelectric layer 103 and the projections of the first and second aerial parts 1061 and 1081 on the piezoelectric layer 103 are offset from each other, so that transverse waves can be suppressed more effectively. The air gap 303 is formed to have a certain length and to be distributed along the edges of the effective resonance area other than the first and second overhead portions 1061 and 1081.

In this embodiment, the air side gap 303 may also serve as a release hole, so that it is possible to select not to release the first sacrificial protrusion 109a during the fabrication of the first substrate, but to release the first sacrificial protrusion 109a and the second sacrificial protrusion 109b simultaneously after the formation of the second electrode 104 and the air side gap 303.

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

Example III

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

Based on fig. 5, after the first electrode 102 is formed, the first protrusion 122a is formed on the first electrode 102, and the first protrusion 122a is distributed along the boundary of the resonance portion of the first electrode and encloses 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 the second electrode 104 is formed, the second protrusion 122b is formed on the second electrode 104, the second protrusion 122b is distributed along the boundary of the second electrode resonance portion 107, and forms a closed or gapped ring shape with the projection of the second gap 120b on the surface of the piezoelectric layer 103. Note that, when the first electrode 102 is formed, the first protrusion 122a may be etched to form the first protrusion 122a, or the first protrusion 122a may be formed after the first electrode 102 is formed; similarly, when the second bump 122b is formed on the second electrode 104, the second bump 122b may be etched, or the second bump 122b may be formed after the second electrode 104 is formed.

In the present 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 part of the surface of the edge of the first electrode resonance portion 105;

forming a first bump material layer covering the mask layer and the exposed first electrode resonance portion 105;

The mask layer is removed to form the first bump 122a.

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, ensuring the integrity of the piezoelectric layer 103.

The first projection 122a is a continuous whole or includes a plurality of first sub-projections intermittently provided.

The second bump 122b is formed by a mask layer similar to the first bump 122a, and the mask layer is formed on the piezoelectric layer 103 and the first electrode 102, so that the mask layer can expose a part of the first electrode 102 at the edge, and then the first bump 122a is formed by patterning, so that the piezoelectric layer 103 and the first electrode 102 are not etched, the integrity of the piezoelectric layer 103 and the first electrode 102 is ensured, and the overall structural stability of the formed resonator is further ensured.

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

In the present embodiment, when the first protrusion 122a is a continuous whole or when the first protrusion 122a is a continuous whole, the first protrusion 122a is fitted to the first aerial part 1061 to enclose a closed ring shape, or the second protrusion 122b and the second aerial part 1061 are fitted to enclose a closed ring shape at the boundary of the effective resonance region, it is more advantageous to prevent lateral leakage of sound waves. In other embodiments, only the first protrusion 122a or the second protrusion 122b may be included, the first protrusion 122a and the first overhead portion 1061 may be looped, or the second protrusion 122b and the second overhead portion 1061 may be looped. The pattern enclosed by the first protrusion 122a and the first overhead portion 1061, or the second protrusion 122b and the second overhead portion 1061, may not be a closed loop.

The projections of the first protrusion 122a and the second protrusion 122b on the surface of the piezoelectric layer 103 may enclose a closed or non-closed ring shape.

Specifically, the first protrusion 122a and the second protrusion 122b may be a continuous whole or may include a plurality of sub-protrusions intermittently disposed, and the first protrusion 122a and the second protrusion 122b may enclose a closed loop or an unsealed loop.

Referring to fig. 14, the case where the projections of the first protrusion 122a and the second protrusion 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 formed as a continuous whole, the first protrusion 122a and the second protrusion 122b may be formed as a closed loop alone, or the first protrusion 122a and the second protrusion 122b may be disposed opposite to each other, and complementarily form a closed loop.

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

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 encloses a closed ring shape, which is not limited thereto; the projection of the first protrusion 122a and the second protrusion 122b on the surface of the piezoelectric layer 103 may be that: when the first protrusion 122a and the second protrusion 122b are all continuous and integral, the projections of the first protrusion 122a and the second protrusion 122b on the piezoelectric layer 103 may enclose an unsealed ring shape, and when the projections of the first protrusion 122a and the second protrusion 122b on the surface of the piezoelectric layer 103 enclose an unsealed ring shape when the projections of the first protrusion 122a and the second protrusion 122b on the surface of the piezoelectric layer 103 are a plurality of sub-protrusions arranged intermittently and are not complementary, the projection of the first protrusion 122a and the second protrusion 122b on the surface of the piezoelectric layer 103 encloses an unsealed ring shape, and the case 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, the material may be the same as that 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, any one of silicon oxide, silicon nitride, silicon oxynitride, or silicon carbonitride may be used, but is not limited thereto.

In other embodiments, only at least one of the first protrusion 122a and the second protrusion 122b may be included. It should be appreciated that when both the first projection 122a and the second projection 122b are included, it is more advantageous to prevent lateral leakage of sound waves.

Example IV

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

The specific method comprises the following steps:

Referring to fig. 5, after the first electrode 102 is formed, a first dielectric layer 121a is formed on the piezoelectric layer 103 in the inactive region and is spaced apart from the first electrode resonant portion 105, the first dielectric layer 121a and the first electrode lead-out portion 106 are continuously connected, the first dielectric layer 121a is located at the periphery of the active resonant region and forms a gap between the edge of the active resonant region and the edge of the first electrode resonant portion 105, and the first dielectric layer 121a and the first overlap portion 1062 surround the first electrode resonant portion 105; the first dielectric layer 121a and the first overlap portion 1062 are connected to each other and complementary to each other on the surface of the piezoelectric layer 103, and form a ring shape around the surface of the piezoelectric layer 103, and cover 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, etc.

And, based on fig. 8, after forming the second electrode 104, further includes:

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, the second dielectric layer 121b and the second electrode lead-out portion 108 are continuously connected, 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 overlap portion 1082 surround the second electrode resonance portion 107. The second dielectric layer 121b and the second overlap 1082 are connected and complementary to each other on the surface of the piezoelectric layer 103, and form a loop around the surface of the piezoelectric layer 103, and cover the area outside the edge of the effective resonance area. The material of the second dielectric layer 121b refers to the material of the first dielectric layer 121a, and will not be described herein.

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, respectively, to form a gap, and the first electrode resonance portion 105 and the second electrode resonance portion 107 are exposed to air, so that the 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 later, 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 lap joint portion 1062, and the surface of the second dielectric layer 121b is flush with the surface of the second lap joint portion 1082, so as to improve mechanical strength and bonding effect of the top cover.

Example five

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

Specifically, referring to fig. 17, the first protrusion 107a and the first dielectric layer 121a may be formed simultaneously or not, 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 simultaneously;

Also, referring to fig. 18, the second bump 107b and the second dielectric layer 121b may be formed simultaneously or not, and may be formed simultaneously when the second bump 107b and the second dielectric layer 121b are the same material.

Fig. 19 shows a top view of fig. 18, and referring to fig. 19, the present embodiment includes a first bump 107a, a second bump 107b, a first dielectric layer 121a, and a second dielectric layer 121b.

It should be appreciated that when the first protrusion 122a, the second protrusion 107b, the first dielectric layer 121a, and the second dielectric layer 121b are simultaneously included, it can be more advantageous to suppress the transverse wave leakage, to increase the mechanical strength, and to improve the effect of the top cover bonding.

In other embodiments, only at least 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 will not be described herein.

Example six

In other embodiments of the present invention, based on fig. 9, further comprising forming a cap on the piezoelectric layer 103, the cap including a second cavity 110b, the second electrode resonance portion 107 being located within the second cavity 110 b.

In one embodiment, a method of forming a top cover includes:

Providing a second substrate 300;

Forming a bonding layer 301 on the second substrate 300;

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

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 on 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 supporting layer 101, and the connection manner between the second substrate 300 and the bonding layer 301 is the same as that between the previous base 101' and the supporting layer 101, which is not described herein.

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

Referring to fig. 21, a bonding layer 301 is bonded to a piezoelectric layer; the steps for forming the second cavity 110b are the same as the methods for forming the first cavity 110a described above, and will not be repeated here. The top cover is formed on the piezoelectric layer 103 through the bonding process, so that the layers exposed to the upper space are prevented from being polluted by the external environment, and meanwhile, the piezoelectric layer on the first cavity 110a can be prevented from being deformed under pressure, and the quality of the resonator is further ensured. The top cover is thus preferably formed by means of a bond in this embodiment.

The solution 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 in which the top cover is formed with any one of the methods described above, at least one of the first protrusion 122a and the second protrusion 122b is formed. An acoustic impedance mismatch region is formed in the region of the first protrusion 122a and/or the second protrusion 122b to reflect the energy that is out-diffused in the effective resonance region back into the effective resonance region, thereby suppressing leakage of transverse waves.

When the first protrusion 122a and the second protrusion 122b are simultaneously included, it is more advantageous to suppress the leakage of the transverse clutter, reducing the energy loss.

Referring to fig. 23, in an embodiment having a top cover formed by any one of the methods described above, 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 simultaneously included, it is more advantageous to suppress transverse wave leakage, to increase mechanical strength, and to improve the effect of top cover bonding.

Referring to fig. 24, in still another embodiment, in the top cover embodiment formed by any one of the methods described above, at least one of the first dielectric layer 121a and the second dielectric layer 121b, and at least one of the first bump 122a and the second bump 122b may also be formed.

When the first protrusion 122a, the second protrusion 122b, the first dielectric layer 121a and the second dielectric layer 121b are simultaneously included, the effects of suppressing the leakage of the lateral clutter, reducing the energy loss, improving the mechanical strength and improving the bonding of the top cover can be more facilitated

In summary, since the first electrode 102 includes the first electrode resonant portion 105 and the first electrode lead-out portion 106, and the second electrode 104 includes the second electrode resonant 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 form the first gap 120a and the second gap 120b in the boundary region of the effective resonant region, respectively, and the first gap 120a and the second gap 120b can achieve the effect of eliminating boundary clutter in the effective resonant region, thereby improving the Q value of the resonator.

By forming the piezoelectric layer on the surface of the temporary substrate, the piezoelectric layer can be formed on the flat temporary substrate, so that the piezoelectric layer is ensured to have better lattice orientation, the piezoelectric property of the piezoelectric layer is improved, and the performance of the resonator is further improved. The first electrode is formed on the first surface of the piezoelectric layer, and the second electrode is formed on the second surface, so that the electrode patterning process is carried out on the two sides of the piezoelectric layer, the etching of the piezoelectric layer in the electrode forming process is avoided, the integrity and 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 main process of the resonator, and the flow is simple.

Further, when the piezoelectric layer is a complete membrane layer, the structural strength of the resonator can be increased; when the piezoelectric layer is provided with an air gap, the edge of the piezoelectric layer is exposed to air, so that the transverse wave loss can be suppressed.

Further, the first protrusion 122a is disposed on the surface of the first electrode 102 and/or the second protrusion 122b is disposed on the surface of the second electrode 104, where the first protrusion 122a and the second protrusion 122b are located, form an acoustic impedance mismatch area, which can be mismatched with acoustic impedance inside the effective resonance area at the boundary of the effective resonance area, and the projections of the first protrusion 122a and the first aerial part 1061 on the surface of the piezoelectric layer 103 are closed or ring-shaped with a gap, or the projections of the second protrusion 122b and the second aerial part 1081 on the surface of the piezoelectric layer 103 are closed or ring-shaped with a gap, which can jointly play a role in inhibiting the leakage of transverse clutter, so that the quality factor of the resonator is further improved;

Further, the first dielectric layer 121a and the second dielectric layer 121b are formed on the upper and lower surfaces of the piezoelectric layer 103, respectively, so that the bonding effect can be improved when the top cover is subsequently formed, and the mechanical strength of the entire resonator can be improved by providing the first dielectric layer 121a and the second dielectric layer 121 b.

It should be noted that, in the present specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment is mainly described in a different point from other embodiments. In particular, for structural embodiments, since they are substantially similar to method embodiments, the description is relatively simple, and reference is made to the description of method embodiments for relevant points.

The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.

Claims

1. A method of manufacturing a thin 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 resonant area;

After forming a first electrode, forming a first dielectric layer on the piezoelectric layer in the ineffective area, and separating the first dielectric layer from the first electrode resonance part, wherein the first dielectric layer is continuously connected with the first electrode lead-out part;

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, the first electrode lead-out part extends to the periphery of the first cavity, and the first surface and the second surface of the piezoelectric layer are both planes and cover the first cavity and extend out of the first cavity;

removing the temporary substrate;

After forming a second electrode, forming a second dielectric layer on the piezoelectric layer in the ineffective area, and separating the second dielectric layer from the second electrode resonance part, wherein the second dielectric layer is continuously connected with the second electrode lead-out part;

And removing the first sacrificial bulge and the second sacrificial bulge, wherein the first electrode lead-out part forms a first gap between the edge of the effective resonance area and the edge of the first electrode resonance part and the first surface of the piezoelectric layer, and the second electrode lead-out part forms a second gap between the edge of the effective resonance area and the edge of the second electrode resonance part and the second surface of the piezoelectric layer.

2. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein projections of the first electrode lead-out portion and the second electrode lead-out portion on the surface of the piezoelectric layer are offset from each other.

3. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein projections of the first and second voids on the piezoelectric layer enclose a closed ring shape or a ring shape with voids.

4. The method according to claim 1, wherein the first electrode lead-out portion includes a first overhead portion surrounding the first space, a first lap-joint portion extending to an inactive area as a signal connection end, the first lap-joint portion surrounding an outer periphery of the first electrode resonance portion or the first lap-joint portion being provided at a part of the outer periphery of the first electrode resonance portion; the first overhead part surrounds the outer periphery of the first electrode resonance part, or the first overhead part is arranged on part of the outer periphery of the first electrode resonance part.

5. The method of manufacturing a thin film bulk acoustic resonator according to claim 4, wherein the second electrode lead-out portion includes a second overhead portion surrounding the second void, a second lap portion extending to an inactive area as a signal connection terminal; the second lap joint part surrounds the outer periphery of the second electrode resonance part, or is arranged on part of the outer periphery of the second electrode resonance part; the second overhead part surrounds the outer periphery of the second electrode resonance part, or the second overhead part is arranged on part of the outer periphery of the second electrode resonance part.

6. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the method of forming the first electrode comprises:

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

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

7. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the method of forming the second electrode comprises:

forming a second conductive layer covering 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, wherein the first protrusions are distributed along the boundary of the first electrode resonance part;

the method for forming the first bump includes:

When the first electrode is formed by etching, the first protrusion is also formed by etching, and the first protrusion and the first electrode are made of the same material;

or forming the first bump after forming the first electrode.

9. The method of manufacturing a thin film bulk acoustic resonator according to claim 8, wherein the projection of the first protrusion and the first void on the surface of the piezoelectric layer encloses a closed or gapped ring shape.

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

Forming second protrusions on the second electrode, wherein the second protrusions are distributed along the boundary of the second electrode resonance part;

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

Or forming the second bump after forming the second electrode.

11. The method of manufacturing a thin film bulk acoustic resonator according to claim 10, wherein the projection of the second bump and the second void on the surface of the piezoelectric layer encloses a closed or gapped ring.

12. The method of manufacturing a thin film bulk acoustic resonator according to any one of claims 8 or 9, wherein the first bump comprises a dielectric material; or alternatively

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

13. The method of manufacturing a thin film bulk acoustic resonator according to any one of claims 10 or 11, characterized in that the material of the second bump comprises a dielectric material; or the material of the second bump is the same as the material of the second electrode.

14. The method of manufacturing a thin film bulk acoustic resonator according to claim 5, characterized in that before or after forming the second electrode, further comprising:

Etching the edge area of the effective resonance area to form an air side gap penetrating through the piezoelectric layer and communicated with the first cavity, wherein the projection of the air side gap on the piezoelectric layer and the projections of the first overhead part and the second overhead part on the piezoelectric layer are staggered.

15. The method of manufacturing a thin film bulk acoustic resonator according to 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 protrusion after forming the second electrode lead-out portion;

Or alternatively

After forming the second electrode lead-out portion, an air gap is formed through the piezoelectric layer, releasing the first and second sacrificial protrusions at the same time.

16. A method of fabricating a thin film bulk acoustic resonator as claimed in any one of claims 1 or 15 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.

17. 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 to the piezoelectric layer;

Or alternatively

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 supporting layer;

the support layer and the base form the first substrate.

18. The method of 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 surrounded by the second cavity.