CN115412046A

CN115412046A - Film bulk acoustic resonator and manufacturing method thereof

Info

Publication number: CN115412046A
Application number: CN202110594618.5A
Authority: CN
Inventors: 李伟; 罗海龙
Original assignee: Smic Ningbo Co ltd Shanghai Branch
Current assignee: Smic Ningbo Co ltd Shanghai Branch
Priority date: 2021-05-28
Filing date: 2021-05-28
Publication date: 2022-11-29

Abstract

The invention relates to a film bulk acoustic resonator and a manufacturing method thereof, comprising the following steps: providing a resonant cavity main body structure which comprises a first substrate and a piezoelectric laminated structure formed on the first substrate, wherein a first cavity is formed between the first substrate and the piezoelectric laminated structure; forming a reinforcing structure in a peripheral area surrounding the piezoelectric laminated structure, wherein the surface of the reinforcing structure is provided with grooves and/or protrusions; providing a second substrate, and forming an elastic bonding material layer with a second cavity on the second substrate to form a resonator cover body; the reinforcing structure and the resonator cover are bonded together by a layer of resilient bonding material, the second cavity and said first cavity being at least partially aligned. According to the invention, the reinforcing structure with the groove and/or the bulge is formed in the peripheral area of the piezoelectric laminated structure, and the reinforcing structure and the resonator cover body are bonded together through the elastic bonding material layer, so that the elastic bonding material layer is well attached to the groove, the path of water vapor diffusion is prolonged, and the reliability of the product is improved.

Description

Film bulk acoustic resonator and manufacturing method thereof

Technical Field

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

Background

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

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

In the filter capping process, a dry film bonding process is usually adopted, but because the interface between the dry film and the medium is poor in water tightness, water vapor can enter the cavity along the contact boundary of the dry film and the medium, so that the electrode can be corroded by the water vapor to cause the technical problems of poor performance and the like. Therefore, the film bulk acoustic resonator manufactured at present cannot meet the requirement of a high-performance radio frequency system.

Disclosure of Invention

The invention aims to provide a film bulk acoustic resonator and a manufacturing method thereof, which can solve the technical problems that the interface of a dry film and a medium in a dry film bonding process is poor in water tightness, water vapor can enter a cavity to cause electrode corrosion to cause poor performance and the like.

In order to achieve the above object, the present invention provides a method for manufacturing a film bulk acoustic resonator, including:

providing a resonant cavity main body structure, wherein the resonant cavity main body structure comprises a first substrate and a piezoelectric laminated structure formed on the first substrate, and a first cavity is formed between the first substrate and the piezoelectric laminated structure;

forming a reinforcing structure on the peripheral area of the resonant cavity main body structure surrounding the piezoelectric laminated structure, wherein the surface of the reinforcing structure is provided with grooves and/or protrusions;

providing a second substrate, and forming an elastic bonding material layer on the second substrate to form a resonator cover body, wherein the elastic bonding material layer is provided with a second cavity;

the reinforcing structure and the resonator cover are bonded together by the layer of resilient bonding material, and after bonding, the piezoelectric stack is sandwiched between the first substrate and the second substrate, the second cavity and the first cavity being at least partially aligned.

The present invention also provides a film bulk acoustic resonator, comprising:

the resonant cavity comprises a resonant cavity main body structure and a resonant cavity main body structure, wherein the resonant cavity main body structure comprises a first substrate and a piezoelectric laminated structure positioned on the first substrate, and a first cavity is formed between the first substrate and the piezoelectric laminated structure;

the reinforcing structure surrounds the peripheral area of the piezoelectric laminated structure, and the surface of the reinforcing structure is provided with grooves and/or protrusions;

a resonator cap bonded to the reinforcing structure, the resonator cap comprising a layer of resilient bonding material bonded to the reinforcing structure and having a second cavity, the piezoelectric stack being sandwiched between the first substrate and the second substrate, the second cavity being at least partially aligned with the first cavity, and a second substrate.

The invention has the beneficial effects that:

the reinforcing structure with the grooves and/or the protrusions surrounding the piezoelectric laminated structure is formed in the peripheral area of the piezoelectric laminated structure, the elastic bonding material layer is used for bonding the reinforcing structure and the resonator cover together, and finally the elastic bonding material layer is well attached to the grooves and/or the protrusions, so that the interface of the elastic bonding material layer attached to the reinforcing structure is good in water tightness, a water vapor diffusion path is prolonged, and the reliability of a product is improved. The quality factor of the film bulk acoustic resonator is effectively improved by clamping the piezoelectric laminated structure between the first substrate and the second substrate, and at least partially aligning the second cavity and the first cavity.

Furthermore, an effective resonance area of the film bulk acoustic resonator is defined through the first groove and the second groove, the first groove and the second groove penetrate through the first electrode and the second electrode respectively, the complete film layer of the piezoelectric layer is not etched, the structural strength of the film bulk acoustic resonator is guaranteed, and the yield of the manufactured film bulk acoustic resonator is improved.

Further, the conductive interconnection structure is connected with the first electrode and the second electrode outside the effective resonance area, so that the first electrode and the second electrode outside the effective resonance area are in short circuit, no pressure difference exists between the upper part and the lower part of the piezoelectric layer of the piezoelectric laminated structure outside the effective resonance area, and no standing wave oscillation is generated outside the effective resonance area.

Furtherly, highly establishing into 0.3um ~ 1.5um through with the recess, the width is 1um ~ 100um for the elastic bonding material layer can reach better laminating with the recess bottom, makes the water proofness on its laminating interface better, further improves the reliability of product.

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 to 11 are schematic structural diagrams corresponding to different steps in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present invention.

Reference numerals: 10. reinforcing the structure; 100. a first substrate; 101. a support layer; 102. a first electrode; 102', a first electrode layer; 103. a piezoelectric layer; 104. a second electrode; 104', a second electrode layer; 105. etching the stop layer; 106. a dielectric layer; 107. a first trench; 108. a second trench; 109. a groove; 109a, a sacrificial layer; 110. a protrusion; 110a, a first cavity; 110b, a second cavity; 120. a first electrical connection structure; 121. a first conductive interconnect layer; 122. a conductive block; 130. a second electrical connection structure; 131. a second conductive interconnect layer; 140. a conductive interconnect structure; 200. a temporary substrate; 300. a resonator cover; 301. a second substrate; 302. a layer of resilient bonding material.

Detailed Description

The film bulk acoustic resonator and the method for manufacturing the same according to the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and drawings, it being understood, however, that the inventive concepts may be embodied in many different forms and are not limited to the specific embodiments described 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 1

The present embodiment 1 provides a method for manufacturing a film bulk acoustic resonator, including the following steps:

s01: providing a resonant cavity main body structure, wherein the resonant cavity main body structure comprises a first substrate and a piezoelectric laminated structure formed on the first substrate, and a first cavity is formed between the first substrate and the piezoelectric laminated structure;

s02: forming a reinforcing structure on the peripheral area of the resonant cavity main body structure surrounding the piezoelectric laminated structure, wherein the surface of the reinforcing structure is provided with grooves and/or protrusions;

s03: providing a second substrate, and forming an elastic bonding material layer on the second substrate to form a resonator cover, wherein the elastic bonding material layer is provided with a second cavity;

s04: the reinforcing structure and the resonator cover are bonded together by the layer of resilient bonding material, and after bonding, the piezoelectric stack is sandwiched between the first substrate and the second substrate, the second cavity and the first cavity being at least partially aligned.

Fig. 1 to 9 are schematic cross-sectional structural diagrams corresponding to corresponding steps of a method for manufacturing a thin film bulk acoustic resonator according to this embodiment, and the method for manufacturing a thin film bulk acoustic resonator according to this embodiment will be described in detail with reference to fig. 1 to 9.

Referring to fig. 1 to 3, step S01 is performed to provide a resonant cavity body structure, where the resonant cavity body structure includes a first substrate 100 and a piezoelectric stack structure formed on the first substrate 100, and a first cavity 110a is formed between the first substrate 100 and the piezoelectric stack structure.

The forming method of the resonant cavity main body structure comprises the following steps:

referring to fig. 1, a temporary substrate 200 is provided, and a piezoelectric stack structure film is formed on the temporary substrate 200.

The temporary substrate 200 may be any suitable substrate known to those skilled in the art, and may be, for example, at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III/V compound semiconductors, 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 (DSP), or may be a ceramic substrate such as alumina, quartz, or a glass substrate.

The piezoelectric laminated structure film sequentially comprises a second electrode layer 104', a piezoelectric layer 103 and a first electrode layer 102' which are sequentially arranged from bottom to top.

The material of the second electrode layer 104 'and the first electrode layer 102' may be any suitable conductive material or semiconductor material known to those skilled 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 (Cu), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Cr), titanium (Ti), gold (Au), osmium (Os), rhenium (Re), palladium (Pd), or a stack of the above metals, or a semiconductor material such as Si, ge, siGe, siC, siGeC, or the like. The second electrode layer 104 'and the first electrode layer 102' may be formed by physical vapor deposition such as magnetron sputtering and evaporation, or by chemical vapor deposition. 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 (LiNbO 3), quartz (Quartz), potassium niobate (KNbO 3), or lithium tantalate (LiTaO 3), or a combination thereof can be used. 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 (Sc), 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 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. Alternatively, in the present embodiment, the second electrode layer 104 'and the first electrode layer 102' are made of molybdenum (Mo) metal, and the piezoelectric layer 103 is made of aluminum nitride (AlN).

In this embodiment, before forming the piezoelectric laminated structure film, a seed layer (not shown in the figure) is further formed on the temporary substrate 200, where the seed layer has a guiding property for a crystal direction of the piezoelectric laminated structure film to be formed later, so that the piezoelectric laminated structure film to be formed later grows along a specific crystal direction, uniformity of the piezoelectric laminated structure film is ensured, piezoelectric characteristics of the piezoelectric layer are improved, and overall performance of the resonator is further improved. In this embodiment, the seed layer may be formed by a magnetron sputtering or an epitaxial growth process.

After the seed layer is formed and before the piezoelectric stack structure film is formed, the method further includes: and carrying out surface treatment on the seed layer, wherein the surface treatment comprises the following steps: and cleaning the seed layer to remove surface impurities. The cleaning mode comprises the following steps: cleaning the surface of the seed layer by using a chemical reagent or deionized water to remove surface impurities and defects, wherein the chemical reagent comprises SC1, SC2, SPM, DHF or an organic solvent; ultrasonic vibration, heating and/or vacuum pumping processes are also carried out when the surface is cleaned. The SC1 solution is a mixed solution composed of NH4OH, H2O2 and H2O, the SC2 solution is a mixed solution composed of HCl, H2O2 and H2O, or is an HCl solution, the SPM solution is a mixed solution composed of H2SO4, H2O2 and H2O, and the DHF solution is an HF solution, or is a mixed solution composed of HF, H2O2 and H2O. It should be noted that when heating, it is also necessary to select a suitable heating temperature so that the adsorbed atoms have sufficient energy to migrate to a suitable equilibrium position for epitaxial growth, and the heating temperature of the seed layer is 700 ℃ to 1350 ℃. When the heating temperature is too high, the adsorbed atoms are evaporated again and desorbed, and when the heating temperature is too low, a polycrystalline or amorphous layer may be grown.

Referring to fig. 2 and 3, a support layer 101 is formed on the piezoelectric stack structure film; patterning the support layer 101 to form a first cavity 110a, wherein the first cavity 110a penetrates through the support layer 101; the first substrate 100 is bonded on the support layer 101, and the first substrate 100 covers the first cavity 110a.

The support layer 101 is formed by physical vapor deposition or chemical vapor deposition. The material of the support layer 101 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.

The first electrode layer 102 'is patterned to form the first electrode 102 by etching the support layer 101 through an etching process to form the first cavity 110a and expose the first electrode layer 102' at the bottom, and the method for patterning the first electrode layer 102 'may be to etch the first electrode layer 102' through the etching process, which may be a wet etching process or a dry etching process, and the dry etching process includes, but is not limited to, reactive Ion Etching (RIE), ion beam etching, and plasma etching. It should be noted that, patterning the first electrode layer 102 'to form the first electrode 102 may be performed simultaneously when etching the support layer 101, or patterning the first electrode layer 102' to form the first electrode 102 first, and forming the support layer 101 on the first electrode 102, which is not limited herein; 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. The shape of the bottom surface of the first cavity 110a may be rectangular or polygonal other than rectangular, such as pentagonal, hexagonal, octagonal, etc., and may also be circular or elliptical.

In addition, before the support layer 101 is formed, an etch stop layer 105 and a dielectric layer 106 are deposited and formed on the first electrode layer 102', and when the support layer 101 is etched, the dielectric layer 106 and the etch stop layer 105 are simultaneously etched to form a first cavity 110a, as shown in fig. 3.

It should be noted that after forming the first cavity 110a and before bonding the first substrate 100, a first trench 107 is formed on the first electrode 102 at the bottom of the first cavity 110a to penetrate the first electrode 102; on one hand, the etching stop layer 105 and the dielectric layer 106 are formed on the piezoelectric laminated structure film, on the other hand, the groove 109 is formed by etching the dielectric layer 106 and the etching stop layer 105, so that the subsequent elastic bonding material layer is tightly attached to the groove 109, the path of water vapor diffusion is prolonged, and the reliability of the product is improved; on the other hand, when the first cavity 110a is formed by etching the support layer 101, over-etching is prevented, and the surface of the first electrode 102 located therebelow is protected from being damaged, so that the performance and reliability of the device are improved. The first trench 107 penetrates the first electrode 102 so that the side of the first electrode 102 surrounding the inner wall of the first trench 102 is exposed to the air, and the electrode material and the air have a large acoustic impedance mismatch so that the acoustic wave in the piezoelectric laminated structure film is emitted at the air interface, thereby preventing the energy of the acoustic wave from leaking.

Referring to fig. 4, the temporary substrate 200 is removed. After the temporary substrate 200 is removed, the film bulk acoustic resonator is turned over.

It should be noted that when the temporary substrate 200 is removed, the seed layer is removed. The method for removing the seed layer comprises the following steps: and removing the seed layer by using a grinding process or an etching process. Specifically, the temporary substrate 200 is thinned by a grinding process, and then the remaining temporary substrate 200 and the seed layer are removed by a wet etching or dry etching process.

The first substrate 100 and the piezoelectric stack structure film on the first substrate 100 constitute the resonator body structure.

Referring to fig. 5 to 9, step S02 is performed, and a reinforcing structure 10 is formed on the resonator body structure around the peripheral region of the piezoelectric stack structure film, where the surface of the reinforcing structure 10 has grooves 109 and/or protrusions 110.

After removing the temporary substrate 200, the second electrode layer 104' is patterned to form the second electrode 104.

In the present embodiment, the forming method of the reinforcing structure 10 includes: after the first electrode layer 102 'is formed and before the support layer 101 is formed, forming an etching stop layer 105 and a dielectric layer 106 on the first electrode layer 102', and after the temporary substrate 200 is removed, etching the piezoelectric laminated structure film and the etching stop layer 105 and the dielectric layer 106 located below the piezoelectric laminated structure film; specifically, the dielectric layer and the etch stop layer 106 are etched to form a groove 109, one surface of the groove 109 penetrates through the etch stop layer 105 and extends into the dielectric layer 106, and the support layer 101, the etch stop layer 105 with the groove 109, and the dielectric layer 106 form the reinforcing structure 10, as shown in fig. 5. The function of forming the etching stop layer 105 and the dielectric layer 106 on the first electrode layer 102' is described above, and is not described herein again.

In an embodiment, after removing the temporary substrate 200, the reinforcing structure is formed by etching the support layer 101, and the forming method specifically includes:

after removing the temporary substrate 200, etching the piezoelectric stack structure film and the support layer 101 located below the piezoelectric stack structure film; specifically, the supporting layer 101 is etched to form the grooves 109, and the supporting layer 101 having the grooves 109 constitutes the reinforcing structure 10, as shown in fig. 6.

In one embodiment, after removing the temporary substrate 200, the piezoelectric stack structure film is etched to expose a portion of the etch stop layer 105; forming a bump material layer on the etching stop layer 105, removing the bump material layer on the piezoelectric stack structure film, and etching the bump material layer to form a bump 110, where the support layer 101, the dielectric layer 106, the etching stop layer 105, and the bump 110 formed on the etching stop layer 105 constitute the reinforcing structure 10, as shown in fig. 7.

In an embodiment, after removing the temporary substrate 200, etching the surface of the support layer 101 facing away from the first substrate 100 to form the groove 109, as shown in fig. 8 a; forming a sacrificial layer 109a in the recess 109, as shown in fig. 8 b; forming a bump material layer on the support layer 101, and etching the bump material layer to form a bump 110; releasing the sacrificial layer 109a; the support layer 101 with the recesses 109 and the protrusions 110 form the reinforcing structure 10, as shown in fig. 8 c.

In another embodiment, after removing the temporary substrate 200, a reinforcing structure 10 is formed on the support layer 101, and the forming method specifically includes:

after removing the temporary substrate 200, etching the piezoelectric stack structure film to expose a part of the support layer 101, forming a reinforced structure film on the support layer 101, and after removing the reinforced structure film on the piezoelectric stack structure film, etching the surface of the reinforced structure film to form a groove 109 and a protrusion 110 so as to form the reinforced structure 10; alternatively, after forming the reinforcing structure film on the support layer 101, after removing the reinforcing structure film on the piezoelectric laminated structure film, the surface of the reinforcing structure film is etched to form the grooves 109 or the protrusions 110 to form the reinforcing structure 10, as shown in fig. 9.

It should be noted that, the above-mentioned groove 109 and protrusion 110 are a concept taking a certain plane as a reference plane, for example, the groove 109 and protrusion 110 are based on the lower surface of the first electrode 102, a portion lower than the lower surface of the first electrode 102 is called the groove 109, and a portion higher than the lower surface of the first electrode 102 is called the protrusion 110, and so on, but not limited to, taking the lower surface of the first electrode 102 as the reference plane, and the selection of the reference plane is determined according to the specific process setting. While several different methods of forming the reinforcing structure 10 have been described above, it should be understood that there are other methods that are not described here.

The reinforcing structure 10 surrounds the piezoelectric stack structure film, and the grooves 109 or the protrusions 110 surround the piezoelectric stack structure film; the number of the grooves 109 or the protrusions 110 may be one or more.

In one embodiment, the number of the grooves 109 is plural, and when the surface of the reinforcing structure 10 has the grooves 109 and the grooves 109 surround the piezoelectric laminated structure film, the plural grooves 109 are concentrically arranged along the center to the periphery of the piezoelectric laminated structure film on a plane parallel to the first substrate 100.

Specifically, the reinforcing structure 10 surrounds the piezoelectric laminated structure film, and when the surface of the reinforcing structure 10 has the grooves 109, the grooves 109 are arranged outward Zhou Tongxin centering on the piezoelectric laminated structure film in a top view, and the grooves 109 are overlapped or contacted with each other in a direction perpendicular to the first substrate 110.

In one embodiment, the number of the protrusions 110 is plural, and when the surface of the reinforcing structure 10 has the protrusions 110 and the protrusions 110 surround the piezoelectric stack film, the plurality of protrusions 110 are concentrically arranged along the center to the periphery of the piezoelectric stack film on a plane parallel to the first substrate 100.

Specifically, the reinforcing structure 10 surrounds the piezoelectric laminated structure film, and when the surface of the reinforcing structure 10 has the protrusions 110, the protrusions 110 are arranged outward Zhou Tongxin centering on the piezoelectric laminated structure film in a plan view, and the protrusions 110 are overlapped or in contact with each other as viewed in a direction perpendicular to the first substrate 100.

In another embodiment, when the surface of the reinforcing structure 10 has grooves 109 and protrusions 110, the grooves 109 and the protrusions 110 are concentrically arranged along the center of the piezoelectric laminated structure film to the periphery on a plane parallel to the first substrate 100, and the projections of the grooves 109 and the protrusions 110 on the first substrate 100 are concentrically arranged, in contact with each other, or cover each other;

in other embodiments, the groove 109 and the protrusion 110 jointly surround the piezoelectric laminated structure film, the projection of the groove 109 and the protrusion 110 on the first substrate 100 is annular, and the projection of the groove 109 and the protrusion 110 are in contact with or overlap each other.

Specifically, the projection of the groove 109 and the protrusion 110 on the first substrate 100 forms a ring, and the ring may be a closed ring or an unclosed ring.

When the surface of the reinforcing structure 10 has the grooves 109 and the protrusions 110, the heights of the grooves 109 and the protrusions 110 in a direction perpendicular to the plane of the first substrate 100 may be the same or different, specifically, the height of the groove 109 may be higher than the height of the protrusion 110, lower than the height of the protrusion 100, or equal to the height of the protrusion 110, which is not limited in this embodiment.

In this embodiment, the height of the groove 109 or the protrusion 110 along the direction perpendicular to the plane of the first substrate 100 is 0.3um to 1.5um, and the width of the groove 109 or the protrusion 110 along the plane parallel to the first substrate 100 is 1um to 100um.

Through highly establishing into 0.3um ~ 1.5um with recess 109, the width is 1um ~ 100um for follow-up elastic bonding material layer can reach better laminating with recess 109 bottom, makes the water proofness at its laminating interface better, further improves the reliability of product. In addition, when the piezoelectric stack structure film is etched, a second trench 108 penetrating through the second electrode 104 is formed on the second electrode 104, the second trench 108 is arranged opposite to the first trench 107, the first trench 107 and the second trench 108 are connected or provided with a gap at two junctions of the projection of the first substrate 100, and the piezoelectric stack structure film after the first trench 107 and the second trench 108 are formed is a piezoelectric stack structure; the area enclosed by the first trench 107 and the second trench 108 is an effective resonance area of the piezoelectric stack structure. The first trench 107 penetrates the first electrode 102, so that the side of the first electrode 102 surrounding the inner wall of the first trench 102 is exposed to the air, and the electrode material and the air have a large acoustic impedance mismatch, so that the acoustic wave in the piezoelectric stack structure is emitted at the air interface, thereby preventing the energy of the acoustic wave from leaking. Similarly, the second trench 108 prevents the energy of the acoustic wave from leaking. In addition, an effective resonance region is defined by the first trench 107 and the second trench 108, so that acoustic impedance mismatch is formed in the region where the first trench 107 and the second trench 108 are located, and thus acoustic wave loss is effectively suppressed. The first trench 107 and/or the second trench 108 are/is at least partially located within the range of the first cavity 110a, the first trench 107 is communicated with the first cavity 110a, and an effective resonance area surrounded by the first trench 107 and the second trench 108 is located above the first cavity 110a, so that when the sound wave longitudinally propagates in the effective resonance area to the air above the first cavity 110a or the second electrode 104, the sound wave is reflected back into the effective resonance area due to the acoustic impedance mismatch between the air and the electrode material, and the effective utilization rate of the sound wave is improved. When the first trench 107 and the second trench 108 are all located within the first cavity 110a, the effective utilization rate of the sound wave located in the effective resonance region is better. An effective resonance area of the thin film bulk acoustic resonator is defined by the first groove 107 and the second groove 108, the first groove 107 and the second groove 108 respectively penetrate through the first electrode 102 and the second electrode 104, and the piezoelectric layer 103 keeps a complete film layer without being etched, so that the structural strength of the thin film bulk acoustic resonator is ensured, and the yield of the manufactured thin film bulk acoustic resonators is improved.

Referring to fig. 10, based on fig. 5, steps S03 and S04 are performed, a second substrate 301 is provided, an elastic bonding material layer 302 is formed on the second substrate 301 to form a resonator cap 300, and the elastic bonding material layer 302 has a second cavity 110b; the reinforcing structure 10 and the resonator cap 300 are bonded together by the layer 302 of elastic bonding material, and after bonding, the piezoelectric stack is sandwiched between the first substrate 100 and the second substrate 301, and the second cavity 110b and the first cavity 110a are at least partially aligned.

The material of the elastic bonding material layer 302 is a photo-curing material and/or a thermosetting material, and can lose elasticity by means of illumination or cooling after heating.

The material selected for the resilient bonding material layer 302 is selected to satisfy: the material of the elastic bonding material layer 302 can be a photo-curing material, a thermosetting material, or a combination of a photo-curing material and a thermosetting material, and can lose elasticity by means of light irradiation and cooling after heating, for example, a dry film. Alternatively, a flowable dry film photoresist material may be applied by a coating process (e.g., spin coating, spray coating, roll coating, or screen printing) or a solid or semi-solid dry film material may be pressed on the second substrate 300 by a laminator to form the elastic bonding material layer 302. For example, a film laminator is used to attach a solid dry film material to the second substrate 300 under a vacuum condition at 80 ℃ to 120 ℃ (e.g., 110 ℃) to form an elastic bonding material layer. The layer of resilient bonding material may be a three layer structure, for example, one layer being a PE protective layer, the middle being a dry film layer, and the other layer being a PET protective layer. The PE protective layer is a film layer based on a special Polyethylene (PE) plastic film, such as a high density polyethylene protective film, medium density polyethylene, and low density polyethylene. The PET protective layer is known as polyethylene terephthalate and is obtained by condensation polymerization reaction of terephthalic acid and ethylene glycol. The PE protective layer and the PET layer are both protective and removed before lamination and before development, so that an intermediate dry film layer having a certain adhesiveness and good photosensitivity is finally interposed between the second substrate 300 and the first substrate 400, and the thickness of the elastic bonding material layer is 10 to 20 μm. Next, the elastic bonding material layer 302 may be further patterned by a dry etching process through a series of photolithography processes including exposure, development, and the like to form the second cavity 110b. Specifically, firstly, a mask is formed on the elastic bonding material layer 302, ultraviolet exposure is carried out under a vacuum condition, standing is carried out for a moment after exposure, and the irradiation dose of the ultraviolet exposure is preferably 200J/cm 2-300 mJ/cm2; then, pre-baking the exposed elastic bonding material layer 302 at a temperature of 100 ℃ to 150 ℃ (e.g., 130 ℃) for 100 seconds to 300 seconds (e.g., 200 seconds); then, at normal temperature, a developing solution is spun onto the pre-baked elastic bonding material layer 302 for a plurality of times (for example, 3 times) to develop the pre-baked elastic bonding material layer 302 to form the elastic bonding material layer 302 having the second cavity 110b, wherein the developing solution is PGMEA and includes propylene glycol methyl ether acetate, and the molecular formula of the propylene glycol methyl ether acetate is C6H12O3. Thus, the resonator cover 300 is completed. The shape and size of the second cavity 110b may be the same as or not the same as those of the first cavity 110a, as long as the second cavity 110b enables the first electrode 102, the piezoelectric layer 103, and the second electrode 104 of the bulk acoustic wave resonant structure to have portions overlapping with the first cavity 110a and the second cavity 110b at the same time after subsequent bonding, thereby forming an effective resonant region of the resonator.

After the resonator cover 300 is completed, a layer 302 of resilient bonding material bonds the reinforcing structure 10 and the resonator cover 300 together. The elastic bonding material layer 302 is finally attached to the bottom of the groove 109 well, so that a water vapor diffusion path is prolonged, and the reliability of the product is improved.

By forming the reinforcing structure 10 with the grooves 109 and/or the protrusions 110 surrounding the piezoelectric laminated structure in the peripheral area of the piezoelectric laminated structure and bonding the reinforcing structure 10 and the resonator cover 300 together through the elastic bonding material layer 302, good bonding of the elastic bonding material layer 302 and the grooves 109 and/or the protrusions 110 is finally achieved, so that the interface of the bonding of the elastic bonding material layer 302 and the reinforcing structure 10 is good in water tightness, a path for water vapor diffusion is prolonged, and the reliability of a product is improved.

Referring to fig. 11, based on fig. 7, fig. 11 and fig. 10 are different in that fig. 10 shows that the surface of the reinforcing structure 10 has grooves 109, fig. 11 shows that the surface of the reinforcing structure 10 has protrusions 110, and the method for forming the protrusions 110 is described above and will not be described again.

After the resonator cover is completed, a layer of resilient bonding material 302 bonds the reinforcing structure 10 and the resonator cover 300 together. The elastic bonding material layer 302 is finally attached to the convex groove 110 well, so that the water vapor diffusion path is prolonged, and the reliability of the product is improved.

With continued reference to fig. 10 and 11, the present embodiment further includes forming a first electrical connection structure 120 and a second electrical connection structure 130, the first electrical connection structure 120 for electrically connecting with the first electrode 102 of the effective resonance area, and the second electrical connection structure 130 for electrically connecting with the second electrode 104 of the effective resonance area.

Further comprising forming a conductive interconnect structure 140 connected to the first electrode 102 and the second electrode 104 outside the active resonance region.

The conductive interconnect structure 140 may be formed after removing the temporary substrate 200 and before forming the second recess 108, may be formed simultaneously with the second recess 108, or may be formed after the piezoelectric stack structure and before bonding with the resonator cap; the conductive interconnection structure 140 can short-circuit the first electrode 102 and the second electrode 104 outside the effective resonance region, and no voltage difference exists between the upper and lower sides of the piezoelectric layer 103 of the piezoelectric stack structure outside the effective resonance region, and no standing wave oscillation is generated outside the effective resonance region.

Wherein forming the first electrical connection structure 120 comprises:

forming a first interconnection hole penetrating through the underlying structure of the first electrode 102 by an etching process, the first interconnection hole exposing the first electrode 102, forming a first conductive interconnection layer 121 in the first interconnection hole by an electroplating process or a physical vapor deposition process, the first conductive interconnection layer 121 covering an inner surface of the first interconnection hole and a portion of a surface of the first substrate 100 at the periphery of the first interconnection hole, and connecting with the first electrode 102; forming an insulating layer on the surface of the first conductive interconnection layer 121 through a deposition process; a conductive block 122 is formed on the surface of the first substrate 100, the conductive block 122 is electrically connected to the first conductive interconnection layer 121, and the conductive block 122 is electrically connected to an external circuit.

The forming method of the second electrical connection structure 130 is similar to the forming method of the first electrical connection structure 120, and is not repeated here.

In this embodiment, the conductive block 122 is made of the same material as the first conductive interconnection layer 121, and is made of copper.

In summary, the reinforcing structure 10 having the grooves 109 and/or the protrusions 110 surrounding the piezoelectric stack structure is formed in the peripheral region of the piezoelectric stack structure, and the elastic bonding material layer 302 bonds the reinforcing structure 10 and the resonator cover 300 together, so that the elastic bonding material layer 302 is bonded to the grooves 109 and/or the protrusions 110 well, the interface where the elastic bonding material layer 302 is bonded to the reinforcing structure 10 has good water tightness, the path of water vapor diffusion is extended, and the reliability of the product is improved. By sandwiching the piezoelectric stack structure between the first substrate 100 and the second substrate 301, the second cavity 110b and the first cavity 110a are at least partially aligned, which effectively improves the quality factor of the film bulk acoustic resonator.

Furthermore, an effective resonance area of the film bulk acoustic resonator is defined by the first trench 107 and the second trench 108, the first trench 107 and the second trench 108 respectively penetrate through the first electrode 102 and the second electrode 104, and the piezoelectric layer 103 keeps a complete film layer without being etched, so that the structural strength of the film bulk acoustic resonator is ensured, and the yield of the manufactured film bulk acoustic resonator is improved.

Further, by connecting the conductive interconnection structure 140 to the first electrode 102 and the second electrode 104 outside the effective resonance region, the first electrode 102 and the second electrode 104 outside the effective resonance region are short-circuited, no voltage difference exists between the upper and lower sides of the piezoelectric layer 103 of the piezoelectric laminated structure outside the effective resonance region, and no standing wave oscillation occurs outside the effective resonance region.

Further, the etching stop layer 105 and the dielectric layer 106 are formed on the piezoelectric laminated structure, on one hand, the groove 109 is formed by etching the dielectric layer 106 and the etching stop layer 105, so that the elastic bonding material layer 302 is tightly attached to the groove 109, the path of water vapor diffusion is prolonged, and the reliability of the product is improved; on the other hand, when the first cavity 110a is formed by etching the support layer 101, over-etching is prevented, and the surface of the first electrode 102 located therebelow is protected from being damaged, so that the performance and reliability of the device are improved.

Further, through setting the height of recess 109 to 0.3um ~ 1.5um, the width is 1um ~ 100um for elastic bonding material layer 302 can reach better laminating with recess 109 bottom, makes the water proofness of its laminating interface better, further improves the reliability of product.

Example 2

Referring to fig. 10, the present embodiment provides a film bulk acoustic resonator, and fig. 10 shows a schematic structural diagram of a film piezoelectric acoustic resonator of embodiment 2, and referring to fig. 10, the film bulk acoustic resonator includes:

the resonant cavity comprises a resonant cavity body structure and a resonant cavity body structure, wherein the resonant cavity body structure comprises a first substrate 100 and a piezoelectric laminated structure positioned on the first substrate 100, and a first cavity 110a is formed between the first substrate 100 and the piezoelectric laminated structure;

the reinforcing structure 10 surrounds the peripheral area of the piezoelectric laminated structure, and the surface of the reinforcing structure 10 is provided with grooves 109 and/or protrusions;

a resonator cover 300 bonded to the reinforcing structure, said resonator cover 300 comprising a layer 302 of resilient bonding material and a second substrate 301, said layer 302 of resilient bonding material being bonded to the reinforcing structure 10, and said layer 302 of resilient bonding material having a second cavity 110b, said piezoelectric stack being sandwiched between said first substrate 100 and said second substrate 301, said second cavity 110b being at least partially aligned with said first cavity 110a.

The reinforcing structure 10 comprises a support layer 101 and a groove 109 or a protrusion on the support layer 101; alternatively, the first and second electrodes may be,

on said supporting layer 101, a reinforcing structure 10 is located, the surface of said reinforcing structure 10 having grooves and protrusions. The specific forming method of the reinforcing structure refers to embodiment 1, and details are not repeated here.

The number of the grooves 109 or the protrusions 110 is one or more; when the number of the grooves 109 or the protrusions 110 is plural and the grooves 109 or the protrusions 110 surround the piezoelectric stack structure, the plural grooves 109 or the protrusions 110 are concentrically arranged along the center to the periphery of the piezoelectric stack structure on a plane parallel to the first substrate 100. Please refer to example 1 for a specific method for forming the recess 109 or the protrusion 110. When the surface of the reinforcing structure 10 has grooves 109 and protrusions 110, the grooves 109 and the protrusions 110 are concentrically arranged along the center and the periphery of the piezoelectric stack structure on a plane parallel to the first substrate 100, and the projections of the grooves 109 and the protrusions 110 on the first substrate 100 are concentrically arranged, contacted with, or overlapped with each other; alternatively, the groove 109 and the protrusion 110 jointly surround the piezoelectric stack structure, the projection of the groove 109 and the protrusion 110 on the first substrate 100 is annular, and the projection of the groove 109 and the protrusion 110 are in contact with or overlap each other.

The height of groove 109 or protrusion 110 along the direction perpendicular to the plane of first substrate 100 is 0.3um ~ 1.5um, groove 109 or protrusion 110 along the width that is on a parallel with first substrate 100 plane is 1um ~ 100um.

The piezoelectric laminated structure comprises a second electrode 104, a piezoelectric layer 103 and a first electrode 102 which are arranged in sequence; further comprising: a first trench 107 located inside the first cavity 110a and penetrating the first electrode 102; a second trench 108, which is disposed opposite to the first trench 107 and penetrates the second electrode 104; the first trench 107 and the second trench 108 meet at two intersections of the projection of the first substrate 100 or are provided with gaps; the area enclosed by the first trench 107 and the second trench 108 is an effective resonance area of the piezoelectric stack structure.

The present embodiment further includes forming a first electrical connection structure 120 and a second electrical connection structure 130, the first electrical connection structure 120 for electrically connecting with the first electrode 102 of the effective resonance region, and the second electrical connection structure 130 for electrically connecting with the second electrode 104 of the effective resonance region. The method further comprises forming a conductive interconnection structure 140, connecting the first electrode 102 and the second electrode 104 outside the effective resonance area, and enabling the first electrode 102 and the second electrode 104 outside the effective resonance area to be in short circuit, so that no pressure difference exists above and below the piezoelectric layer 103 of the piezoelectric laminated structure outside the effective resonance area, and no standing wave oscillation is generated outside the effective resonance area.

In summary, the reinforcing structure 10 having the groove 109 and/or the protrusion 110 surrounding the piezoelectric stack structure is formed in the peripheral region of the piezoelectric stack structure, and the elastic bonding material layer 302 bonds the reinforcing structure 10 and the resonator cover 300 together, so that the elastic bonding material layer 302 and the groove 109 are well bonded, the interface where the elastic bonding material layer 302 and the reinforcing structure 10 are bonded has good water tightness, the path of water vapor diffusion is extended, and the reliability of the product is improved. By sandwiching the piezoelectric stack structure between the first substrate 100 and the second substrate 301, the second cavity 110b and the first cavity 110a are at least partially aligned, which effectively improves the quality factor of the film bulk acoustic resonator.

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.

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 second substrate, and forming an elastic bonding material layer on the second substrate to form a resonator cover, wherein the elastic bonding material layer is provided with a second cavity;

2. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the reinforcing structure surrounds a piezoelectric stack structure, and the groove or protrusion surrounds the piezoelectric stack structure.

3. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the number of the grooves or the projections is one or more.

4. The method of manufacturing a thin film bulk acoustic resonator according to claim 3, wherein the number of the grooves or the projections is plural, and when the grooves or the projections surround the piezoelectric stack, the plural grooves or the projections are arranged concentrically along a center to a periphery of the piezoelectric stack on a plane parallel to the first substrate.

5. The method of claim 1, wherein the height of the groove or protrusion along a direction perpendicular to the plane of the first substrate is 0.3um to 1.5um, and the width of the groove or protrusion along a direction parallel to the plane of the first substrate is 1um to 100um.

6. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the reinforcing structure has a surface having a groove and/or a protrusion, and the thickness of the elastic bonding material layer is varied to accommodate a step height of the groove and/or the protrusion when the reinforcing structure and the resonator lid are bonded together.

7. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the surface of the reinforcing structure has grooves and protrusions, the grooves and the protrusions are concentrically arranged along a center of the piezoelectric stack structure to a periphery thereof on a plane parallel to the first substrate, and projections of the grooves and the protrusions on the first substrate are concentrically arranged, in contact with, or cover each other;

or the groove and the protrusion jointly surround the piezoelectric laminated structure, the projection of the groove and the projection of the protrusion on the first substrate is annular, and the projection of the groove and the projection of the protrusion are in contact with each other or mutually cover.

8. The method of manufacturing a thin film bulk acoustic resonator according to claim 6,

the forming method of the reinforcing structure comprises the following steps:

providing a temporary substrate, and forming a piezoelectric laminated structure on the temporary substrate;

forming a support layer on the piezoelectric stack structure; etching the supporting layer to form a first cavity;

forming a first substrate on the support layer, the first substrate covering the first cavity;

removing the temporary substrate; etching the surface of the support layer, which is far away from the first substrate, to form a groove or a protrusion so as to form a reinforced structure;

alternatively, the first and second electrodes may be,

removing the temporary substrate; forming a reinforcing structure film on the support layer; and etching the surface of the reinforced structure film to form grooves and/or bulges so as to form the reinforced structure.

9. The method of manufacturing a thin film bulk acoustic resonator according to claim 8,

after etching the surface of the support layer, which faces away from the first substrate, to form the groove, the method further includes: forming a sacrificial layer in the groove, forming a protruding material layer on the supporting layer, and etching the protruding material layer to form a protrusion;

releasing the sacrificial layer; the support layer with the grooves and the protrusions constitute the reinforcing structure.

10. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the material of the elastic bonding material layer is a photo-setting material and/or a thermal-setting material.

11. The method of manufacturing a thin film bulk acoustic resonator according to claim 8, wherein the piezoelectric laminated structure includes a second electrode, a piezoelectric layer, and a first electrode that are provided in this order; after forming the support layer and before bonding the first substrate, further comprising:

forming a first groove penetrating through the first electrode on the first electrode at the bottom of the first cavity;

after the supporting layer is bonded with the first substrate and before the reinforcing structure is bonded with the resonator cover body, the method further comprises the following steps of;

forming a second groove penetrating through the second electrode on the second electrode, wherein the second groove is opposite to the first groove, and the first groove and the second groove are connected at two junctions of the projection of the first substrate or are provided with gaps; the area enclosed by the first groove and the second groove is an effective resonance area of the piezoelectric stack structure.

12. The method for manufacturing a film bulk acoustic resonator according to claim 11, further comprising, before or after the step of bonding the reinforcing structure and the resonator lid together:

forming a first electrical connection structure and a second electrical connection structure electrically connected with an external circuit;

the forming method of the first electrical connection structure comprises the following steps:

forming a first interconnection hole through an etching process, the first interconnection hole penetrating from one side of the first substrate and extending onto the first electrode;

forming a first conductive interconnect layer in the first interconnect hole, the first conductive interconnect layer covering an inner surface of the first interconnect hole.

13. The method of manufacturing a thin film bulk acoustic resonator according to claim 12, wherein after the first electrical connection structure and the second electrical connection structure are formed, a conductive block is formed on a surface of the first substrate, the conductive block is electrically connected to an external circuit, and the first conductive interconnection layer is electrically connected to the conductive block.

14. The method of manufacturing a thin film bulk acoustic resonator according to claim 11, further comprising a conductive interconnection structure connecting the first electrode and the second electrode outside the effective resonance region.

15. A film bulk acoustic resonator, comprising:

16. The film bulk acoustic resonator according to claim 15, wherein the number of the grooves or projections is one or more.

17. The film bulk acoustic resonator according to claim 16, wherein the number of the grooves or projections is plural, and when the grooves or projections surround the piezoelectric stack, the plural grooves or projections are arranged concentrically along a center to a periphery of the piezoelectric stack on a plane parallel to the first substrate.

18. The film bulk acoustic resonator according to claim 15, wherein the height of the groove or the protrusion along a direction perpendicular to the plane of the first substrate is 0.3um to 1.5um, and the width of the groove or the protrusion along a direction parallel to the plane of the first substrate is 1um to 100um.

19. The thin film bulk acoustic resonator according to claim 15, wherein the surface of the reinforcing structure has grooves and protrusions, the grooves and the protrusions are concentrically arranged along the center to the periphery of the piezoelectric stack structure on a plane parallel to the first substrate, and projections of the grooves and the protrusions on the first substrate are concentrically arranged, in contact with, or cover each other;

20. The film bulk acoustic resonator according to claim 15, wherein the piezoelectric stack structure comprises a second electrode, a piezoelectric layer, a first electrode, which are arranged in this order; further comprising: a first trench located inside the first cavity and penetrating the first electrode;

the second groove is opposite to the first groove and penetrates through the second electrode;

the first groove and the second groove are connected or provided with a gap at two junctions of the projection of the first substrate; the area enclosed by the first groove and the second groove is an effective resonance area of the piezoelectric stack structure.