A thin film bulk acoustic wave resonator and its manufacturing method and filter

Abstract

The present invention provides a thin film bulk acoustic wave resonator and a manufacturing method and a filter, wherein the thin film bulk acoustic wave resonator comprises: a first substrate, a first cavity is provided on the upper surface of the first substrate; a piezoelectric stack structure is arranged on the upper surface of the first substrate, covering the first cavity, and the piezoelectric stack structure comprises a second electrode, a piezoelectric layer and a first electrode stacked in sequence from bottom to top; a groove, comprising a first groove and / or a second groove, the first groove passes through the first electrode and extends into or passes through the piezoelectric layer, and the second groove passes through the second electrode and extends into or passes through the piezoelectric layer; a reinforcement layer is arranged on at least one side of the first electrode or the second electrode at the bottom position of the groove. The present invention arranges a reinforcement layer at the bottom of the groove, and the reinforcement layer can reinforce the electrode in the groove area to prevent the thin film electrode from being damaged.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor device manufacturing, and in particular to a thin film bulk acoustic wave resonator and a manufacturing method and a filter thereof. Background Art

[0002] With the continuous development of wireless communication technology, in order to meet the multifunctional requirements of various wireless communication terminals, terminal equipment needs to be able to use different carrier spectra to transmit data. At the same time, in order to support sufficient data transmission rate within a limited bandwidth, strict performance requirements are also put forward for the RF system. RF filter is an important part of the RF system, which can filter out interference and noise outside the communication spectrum to meet the signal-to-noise ratio requirements of the RF system and communication protocol. Taking mobile phones as an example, since each frequency band requires a corresponding filter, dozens of filters may need to be set in a mobile phone.

[0003] Generally, a film bulk acoustic wave resonator includes two film electrodes, and a piezoelectric film layer is arranged between the two film electrodes. Its working principle is to utilize the piezoelectric film layer to generate vibration under an alternating electric field. The vibration excites a bulk acoustic wave that propagates along the thickness direction of the piezoelectric film layer. The sound wave is reflected back when it reaches the interface between the upper and lower electrodes and the air, and then reflects back and forth inside the film to form an oscillation. When the sound wave propagates in the piezoelectric film layer at an odd multiple of half the wavelength, a standing wave oscillation is formed.

[0004] However, the cavity-type thin film bulk acoustic wave resonators currently manufactured have problems such as shear wave loss and insufficient structural strength, which prevents the quality factor (Q) from being further improved and low yield rate, and therefore cannot meet the needs of high-performance RF systems. Summary of the invention

[0005] The invention discloses a thin film bulk acoustic wave resonator and a manufacturing method thereof, which can solve the problems of low quality factor caused by transverse wave leakage of the thin film bulk acoustic wave resonator and easy damage of electrodes at the grooves.

[0006] In order to solve the above technical problems, the present invention provides a thin film bulk acoustic wave resonator, comprising:

[0007] A first substrate, wherein a first cavity is provided on an upper surface of the first substrate;

[0008] A piezoelectric stack structure is disposed on the upper surface of the first substrate and covers the first cavity, wherein the piezoelectric stack structure comprises a second electrode, a piezoelectric layer and a first electrode stacked in sequence from bottom to top;

[0009] Grooves, including a first groove and / or a second groove, wherein the first groove penetrates the first electrode and extends into the piezoelectric layer or penetrates the piezoelectric layer, and the second groove penetrates the second electrode and extends into the piezoelectric layer or penetrates the piezoelectric layer;

[0010] A reinforcement layer is disposed on at least one side of the first electrode or the second electrode at the bottom of the groove.

[0011] The present invention also provides a filter, comprising at least one of the above-mentioned thin film bulk acoustic wave resonators.

[0012] The present invention also provides a method for manufacturing a thin film bulk acoustic wave resonator, comprising:

[0013] providing a carrier substrate,

[0014] forming a first electrode, a piezoelectric layer, and a second electrode in sequence on the carrier substrate;

[0015] forming a first substrate with a first cavity on the second electrode;

[0016] removing the carrier substrate;

[0017] The thin film bulk acoustic wave resonator includes a second groove and a second reinforcement layer, and forming the second groove and the second reinforcement layer includes: forming a second reinforcement layer on the carrier substrate before forming the first electrode; after forming the second electrode, forming a second groove above a region of the second reinforcement layer that penetrates the second electrode and extends into or penetrates the piezoelectric layer; and / or,

[0018] The thin film bulk acoustic wave resonator includes a first groove and a first reinforcement layer. The formation of the first groove and the first reinforcement layer includes: after forming the second electrode, forming the first reinforcement layer on the second electrode; after removing the supporting substrate, forming a first groove above the area of ​​the first reinforcement layer that penetrates the first electrode and extends into the piezoelectric layer or penetrates the piezoelectric layer.

[0019] The beneficial effects of the present invention are:

[0020] A groove is set in the piezoelectric stack structure to expose the first electrode or the second electrode and the end face of the piezoelectric layer in the groove, forming an acoustic impedance mismatch area with the gas in the groove, which can effectively prevent the lateral leakage of sound waves and improve the quality factor of the resonator. A reinforcement layer is set at the bottom of the groove, which can reinforce the electrode in the groove area and prevent damage to the thin film electrode.

[0021] Furthermore, the reinforcement layer located outside the groove and at the boundary of the effective resonance area can not only improve the structural strength of the electrode but also form an acoustic impedance mismatch zone in this area, thereby preventing lateral leakage of sound waves and improving the quality factor of the resonator.

[0022] Furthermore, the projection of the groove in the direction of the surface of the first substrate is a ring shape, and the interior of the ring shape is an effective resonance area of ​​the resonator. This arrangement can greatly increase the acoustic impedance mismatch area and further improve the quality factor of the resonator.

[0023] Furthermore, the groove includes a first groove and a second groove, and protrusions are arranged along the inner boundaries of the grooves and the surfaces of the first electrode and the second electrode. In the horizontal direction, the protrusions are arranged relative to the reinforcement layer to form a complete or nearly complete ring to increase the area of ​​impedance mismatch (the boundaries of the effective resonance area all form impedance mismatch areas); in the vertical direction, there is a relative area between the protrusions and the reinforcement layer, which can further increase the degree of impedance mismatch. Such an arrangement can prevent lateral leakage of sound waves to a large extent and improve the quality factor of the resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which like reference numerals generally represent like components.

[0025] Figure 1 A schematic structural diagram of a thin film bulk acoustic wave resonator according to embodiment 1 of the present invention is shown.

[0026] Figure 2 A schematic structural diagram of a thin film bulk acoustic wave resonator according to embodiment 2 of the present invention is shown.

[0027] Figures 3 to 9 A structural schematic diagram corresponding to different steps of a method for manufacturing a thin film bulk acoustic wave resonator in Example 3 is shown.

[0028] Figures 10 to 16 A structural schematic diagram corresponding to different steps of a method for manufacturing a thin film bulk acoustic wave resonator in Example 4 is shown.

[0029] Description of reference numerals:

[0030] 100-carrying substrate; 101-second dielectric layer; 102-second reinforcement layer; 200-first cavity; 201-first electrode; 202-piezoelectric layer; 203-second electrode; 204-first reinforcement layer; 205-support layer; 206-sacrificial layer; 207-dielectric layer; 208-substrate; 110b-second cavity; 40-second groove; 41-first groove; 1021-first protrusion; 2041-second protrusion; 300-base. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will become clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in a variety of different forms and is not limited to the specific embodiments described herein. The drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0032] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0033] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0034] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0035] If the method herein includes a series of steps, the order of the steps presented herein is not necessarily the only order in which the steps can be performed, and some steps may be omitted and / or some other steps not described herein may be added to the method. If the components in a certain figure are the same as those in other figures, although these components can be easily identified in all figures, in order to make the description of the figures clearer, this specification will not mark all the same component numbers in each figure.

[0036] Example 1

[0037] This embodiment provides a thin film bulk acoustic resonator. Figure 1 FIG. 1 is a schematic diagram showing the structure of a thin film piezoelectric acoustic wave resonator of Example 1, please refer to Figure 1 , the thin film bulk acoustic wave resonator comprises:

[0038] A first substrate, wherein a first cavity 200 is provided on an upper surface of the first substrate;

[0039] A piezoelectric stack structure is disposed on the upper surface of the first substrate and covers the first cavity 200. The piezoelectric stack structure includes a second electrode 203, a piezoelectric layer 202 and a first electrode 201 stacked in sequence from bottom to top;

[0040] Grooves, including a first groove 41 and / or a second groove 40, wherein the first groove 41 penetrates the first electrode 201 and extends into or penetrates the piezoelectric layer 202, and the second groove 40 penetrates the second electrode 203 and extends into or penetrates the piezoelectric layer 202;

[0041] A reinforcement layer is disposed on at least one side of the first electrode 201 or the second electrode 202 at the bottom of the groove.

[0042] Specifically, in this embodiment, the first substrate includes a base 300 and a support layer 205 disposed on the base 300, the support layer 205 is bonded to the base 300, and the support layer 205 encloses a first cavity 200, and the first cavity 200 exposes the upper surface of the base 300. In this embodiment, the first cavity 200 is an annular closed cavity, and the first cavity 200 can be formed by etching the support layer 205 through an etching process. However, the technology of the present invention is not limited to this. For example, in another embodiment, the first substrate is a single-layer structure, and the first cavity is disposed in the first substrate. In this embodiment, the support layer 205 is combined with the base 300 by bonding, and the bonding method includes: covalent bonding, adhesive bonding or melt bonding. In this embodiment, the support layer 205 and the base 300 are bonded by a bonding layer, and the material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate.

[0043] In this embodiment, the material of the substrate 300 can be at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), carbon silicon (SiC), carbon germanium silicon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III / V compound semiconductors, including multilayer structures composed of these semiconductors, etc., and can also be a ceramic substrate such as aluminum oxide, a quartz or glass substrate, etc. The material of the support layer 205 can be any suitable dielectric material, including but not limited to one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride and the like.

[0044] In this embodiment, the shape of the bottom surface of the first cavity 200 is a rectangle, but in other embodiments of the present invention, the shape of the bottom surface of the first cavity 200 may also be a circle, an ellipse, or a polygon other than a rectangle, such as a pentagon, a hexagon, etc. A piezoelectric stack structure is provided above the first cavity 200, and the piezoelectric stack structure includes a second electrode 203, a piezoelectric layer 202, and a first electrode 201 from bottom to top. The second electrode 203 is located on the support layer 205, the piezoelectric layer 202 is located on the second electrode 203, and the first electrode 201 is located on the piezoelectric layer 202. The materials of the second electrode 203 and the first electrode 201 can be any suitable conductive material or semiconductor material known to those skilled in the art, wherein the conductive material can be a metal material with conductive properties, for example, made of one of the 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, and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, etc. The second electrode 203 and the first electrode 201 can be formed by physical vapor deposition or chemical vapor deposition methods such as magnetron sputtering and evaporation. The material of the piezoelectric layer 202 can be piezoelectric materials with a wurtzite crystal structure such as aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate, quartz, potassium niobate or lithium tantalate, and combinations thereof. When the piezoelectric layer 202 includes aluminum nitride (AlN), the piezoelectric layer 202 may further include a rare earth metal, such as at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, when the piezoelectric layer 202 includes aluminum nitride (AlN), the piezoelectric layer 202 may further include a transition metal, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). The piezoelectric layer 202 may be deposited and formed using any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition.

[0045] The grooves in this embodiment include a first groove 41 and a second groove 40. The first groove 41 penetrates the first electrode 201 and the piezoelectric layer 202, and the second groove 40 penetrates the second electrode 203 and the piezoelectric layer 202. In this embodiment, the inner sidewall of the groove constitutes at least a part of the boundary of the effective resonance region, and the first electrode 201, the piezoelectric layer 202 and the second electrode 203 in the effective resonance region overlap each other in a direction perpendicular to the surface of the piezoelectric layer 202. In this embodiment, a first reinforcement layer 204 is arranged on the second electrode 203 at the bottom position of the first groove 41, and a second reinforcement layer 102 is arranged on the first electrode 201 at the bottom position of the second groove 40. In this embodiment, the first reinforcement layer 204 is arranged on the surface of the second electrode close to the first cavity 200, and the second reinforcement layer 102 is arranged on the surface of the first electrode 201 away from the first cavity 200. In other embodiments, the first reinforcement layer may also be disposed on the surface of the second electrode away from the first cavity, or on both the upper and lower surfaces of the first electrode. Similarly, the second reinforcement layer may be disposed on any surface of the first electrode or on both surfaces of the first electrode. The first groove 41 and / or the second groove 40 allow the end surface of the electrode and the end surface of the piezoelectric layer to contact the air, thereby causing the acoustic impedance mismatch in the area where the grooves are located, thereby preventing the leakage of transverse waves in the effective area and improving the Q value of the resonator. The reinforcement layer can reinforce the electrode in the groove area and prevent the thin film electrode from being damaged.

[0046] The material of the reinforcement layer includes a conductive material or a dielectric material. When the material of the reinforcement layer is a conductive material, in a preferred embodiment, the material of the first reinforcement layer is the same as the material of the second electrode, and the material of the second reinforcement layer is the same as the material of the first electrode. The dielectric material includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, etc.

[0047] In this embodiment, the area enclosed by the inner side walls of the first groove 41 and the second groove 40 is an effective resonance zone, and the projections of the inner side walls of the two in the direction of the surface of the piezoelectric layer are a closed figure, which is an irregular polygon. The first electrode 210, the piezoelectric layer 202, and the second electrode 203 in the effective resonance zone are superimposed on each other in a direction perpendicular to the surface of the piezoelectric layer. In a typical example, the first groove 41 and the second groove 40 are both continuous structures and are arranged opposite to each other, and the projections of the two ends of the two are connected. The first groove and / or the second groove can be an intermittent structure, and the projections of the two are complementary to each other to form a closed figure. In another embodiment, the groove includes the first groove 41 and the second groove 40, and the inner side walls of the two only constitute a portion of the boundary of the effective resonance zone.

[0048] In another embodiment, the first groove and / or the second groove extends to a partial depth in the piezoelectric layer and does not penetrate the piezoelectric layer. In other embodiments, the groove may include only the first groove or the second groove. When the groove includes the first groove, a first reinforcement layer is provided at the bottom of the first groove and at the corresponding position of the second electrode 203. When the groove includes the second groove, a second reinforcement layer is provided at the bottom of the second groove and at the corresponding position of the first electrode 201.

[0049] In this embodiment, the projection of the bottom of the first groove 41 in the surface direction of the piezoelectric layer 202 is located within the range of the projection of the first reinforcement layer 204 in the surface direction of the piezoelectric layer 202, and the projection of the bottom of the second groove 40 in the surface direction of the piezoelectric layer 202 is located within the range of the projection of the second reinforcement layer 102 in the surface direction of the piezoelectric layer 202, that is, the reinforcement layer completely covers the bottom area of ​​the groove, and the reinforcement layer located outside the groove and at the boundary of the effective resonance zone can not only improve the structural strength of the electrode but also form an acoustic impedance mismatch zone in this area, thereby preventing lateral leakage of sound waves and improving the quality factor of the resonator.

[0050] Example 2

[0051] The difference between this embodiment and the first embodiment is that a protrusion is arranged at the boundary of the effective resonance region, and the protrusion is arranged opposite to the reinforcement layer. The other structures are the same as those of the first embodiment.

[0052] refer to Figure 2 Specifically, in the present embodiment, the protrusion includes a first protrusion and a second protrusion. A second protrusion 2041 is provided on the horizontally opposite side of the first reinforcement layer 204 and the area where the inner side wall of the second groove 40 is located, and a first protrusion 1021 is provided on the horizontally opposite side of the second reinforcement layer 102 and the area where the inner side wall of the first groove 41 is located. In the present embodiment, the first protrusion 1021 is made of the same material as the second reinforcement layer, and the thickness of the two is also the same, and the two are formed in a synchronous process; the second protrusion 2041 is made of the same material as the first reinforcement layer 204 and the thickness of the two is also the same, and the two are formed in a synchronous process. In other embodiments, the materials of the protrusion and the reinforcement layer may also be different, and the heights may also be different. Providing a protrusion at the boundary of the effective resonance zone can achieve impedance mismatch between the area where the protrusion is located and the effective resonance zone, prevent shear wave leakage in the effective resonance zone, and improve the Q value of the resonator. In an optional solution, the projection of the first protrusion 1021 and the second reinforcement layer 102 on the surface of the piezoelectric layer forms a closed figure and / or the projection of the second protrusion 2041 and the first reinforcement layer 204 on the surface of the piezoelectric layer forms a closed figure.

[0053] In the horizontal direction, the first protrusion 1021 is arranged opposite to the second reinforcement layer 102 to form a complete or nearly complete ring. In the horizontal direction, the second protrusion 2041 is arranged opposite to the first reinforcement layer 204. This arrangement increases the impedance mismatch area (the boundaries of the effective resonance area all form an impedance mismatch area); in the vertical direction, the first protrusion 1021 and the first reinforcement layer 204 have a relative area, and in the vertical direction, the second protrusion 2041 and the second reinforcement layer 102 have a relative area. This arrangement can further increase the degree of impedance mismatch. The above arrangement can largely prevent the lateral leakage of sound waves and improve the quality factor of the resonator. .

[0054] An embodiment of the present invention provides a filter, comprising at least one thin film bulk acoustic wave resonator in embodiment 1 and / or embodiment 2.

[0055] Example 3

[0056] Embodiment 3 provides a method for manufacturing a thin film bulk acoustic wave resonator, comprising the following steps:

[0057] S01: providing a carrier substrate,

[0058] S02: forming a first electrode, a piezoelectric layer, and a second electrode in sequence on the carrier substrate;

[0059] S03: forming a first substrate with a first cavity on the second electrode;

[0060] S04: removing the carrier substrate;

[0061] S05: The thin film bulk acoustic wave resonator includes a second groove and a second reinforcement layer, and forming the second groove and the second reinforcement layer includes: forming a second reinforcement layer on the supporting substrate before forming the first electrode; forming a second groove above the area of ​​the second reinforcement layer after forming the second electrode, which passes through the second electrode and extends into the piezoelectric layer or passes through the piezoelectric layer; and / or, the thin film bulk acoustic wave resonator includes a first groove and a first reinforcement layer, and forming the first groove and the first reinforcement layer includes: forming the first reinforcement layer on the second electrode after forming the second electrode; and forming a first groove above the area of ​​the first reinforcement layer after removing the supporting substrate, which passes through the first electrode and extends into the piezoelectric layer or passes through the piezoelectric layer.

[0062] Steps S0N do not represent a sequential order.

[0063] Figures 3 to 9 FIG. 1 is a schematic diagram showing the structure of different steps of a method for manufacturing a thin film piezoelectric acoustic wave resonator according to Embodiment 3 of the present invention. Figures 3 to 9 , explaining each step in detail.

[0064] refer to Figure 3 , perform step S01: provide a carrier substrate 100.

[0065] The carrier substrate 100 can be at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), carbon silicon (SiC), carbon germanium silicon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III / V compound semiconductors, or a ceramic substrate such as aluminum oxide, a quartz or glass substrate, etc.

[0066] In this embodiment, the thin film bulk acoustic wave resonator includes both a first groove and a first reinforcement layer and a second groove and a second reinforcement layer. The inner sidewall of the first groove and / or the second groove constitutes at least a part of the boundary of the effective resonance region, and the first electrode, the piezoelectric layer and the second electrode in the effective resonance region are overlapped with each other in a direction perpendicular to the surface of the piezoelectric layer. After executing step S01, the second reinforcement layer is formed in step S05. Specifically, refer to Figure 3 , forming a second reinforcement material layer on the carrier substrate 100, patterning the first reinforcement material layer to form the second reinforcement layer 102, forming a second dielectric layer 101 on the carrier substrate 100 and at the periphery of the second reinforcement layer, so that the surface of the second dielectric layer 101 is flush with the surface of the second reinforcement layer 102. The material of the second reinforcement layer refers to Example 1, and the second reinforcement material layer can be formed by a deposition method. The second dielectric layer needs to be removed in the later process, and the second dielectric layer is selected from a material that is easy to remove, such as low-temperature silicon dioxide, polyimide, amorphous carbon or germanium. The structural form and function of the first groove and the first reinforcement layer refer to Example 1.

[0067] In this embodiment, the thin film bulk acoustic wave resonator also includes a first protrusion 1021 that is arranged horizontally opposite to the second reinforcement layer 102. The positional relationship between the first protrusion 1021 and the second reinforcement layer 102 refers to Example 2. In this embodiment, the first protrusion 1021 is formed synchronously with the second reinforcement layer 102, and the formation of the first protrusion 1021 includes: forming a reinforcement material layer, and graphing the reinforcement material layer to form the second reinforcement layer 102 and the first protrusion 1021, and the material and height of the first protrusion and the reinforcement layer are the same. In other embodiments, the first protrusion and the second reinforcement layer can also be formed separately, in which case the material or height of the first protrusion and the reinforcement layer can be the same or different. The structure, positional relationship and function of the protrusion and the reinforcement layer refer to the relevant description of Example 1 and Example 2.

[0068] refer to Figure 4, execute step S02, and sequentially form a first electrode 201, a piezoelectric layer 202 and a second electrode 203 on the second dielectric layer, the second reinforcement layer and the first protrusion 1021. The materials and formation methods of the three are the same as those in Example 1 and will not be repeated here.

[0069] refer to Figure 5 , perform step S05 of forming the first reinforcement layer 204. A first reinforcement material layer is formed on the surface of the second electrode 203 by a deposition process, and the first reinforcement material layer is patterned to form the first reinforcement layer 204. In this embodiment, the thin film bulk acoustic wave resonator also includes a second protrusion 2041 arranged horizontally opposite to the first reinforcement layer 204. The positional relationship between the second protrusion 2041 and the first reinforcement layer 204 refers to Example 2. In this embodiment, the second protrusion 2041 is formed synchronously with the first reinforcement layer 204, and the formation of the second protrusion 2041 includes: forming a reinforcement material layer, patterning the reinforcement material layer to form the first reinforcement layer 204 and the second protrusion 2041, and the material and height of the second protrusion and the first reinforcement layer are the same. In other embodiments, the second protrusion and the first reinforcement layer can also be formed separately, in which case the material or height of the second protrusion and the first reinforcement layer can be the same or different.

[0070] refer to Figures 6 to 8 , S03: forming a first substrate with a first cavity 200 on the second electrode 203. Figure 6 The support layer 205 is formed by physical vapor deposition or chemical vapor deposition to cover the second electrode 203, the first reinforcement layer 204 and the second protrusion 2041. The material of the support layer 205 can 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. Figure 7 , the support layer 205 is patterned to form the first cavity 200. In this embodiment, the first cavity 200 penetrates the support layer 205. The first cavity exposes the first reinforcement layer 204 and the second protrusion 2041. The structure of the first cavity 200 refers to Example 1. In this embodiment, after the second electrode 203 is formed, a second groove 40 penetrating the second electrode 203 and the piezoelectric layer 202 is formed above the area of ​​the second reinforcement layer 102, and the projection of the bottom of the second groove 40 in the surface direction of the piezoelectric layer 202 is located within the range of the projection of the second reinforcement layer 102 in the surface direction of the piezoelectric layer 202. It should be noted that the second groove can be formed before the support layer 205 is formed, or it can be formed after the first cavity 200 is formed. In this embodiment, the second groove 40 is formed on the side of the second protrusion 2041 away from the effective resonance area. The second protrusion 2041 and the second reinforcement layer 102 are provided with an overlapping area in a direction perpendicular to the surface of the piezoelectric layer, and the overlapping area has a stronger impedance mismatching effect.

[0071] refer to Figure 8 , providing a substrate 300, bonding the substrate 300 to the support layer 205, covering the first cavity 200, the first substrate comprising the support layer 205 and the substrate 300. The material of the substrate 300 and the bonding method of the substrate 300 and the support layer 205 refer to Example 1, which will not be repeated here.

[0072] refer to Fig. 9 , perform step S04: remove the carrier substrate 100. The carrier substrate 100 may be removed by grinding, wet etching or etching. In this embodiment, the second dielectric layer 101 is also removed.

[0073] Example 4

[0074] Figures 10 to 16 FIG. 4 shows a schematic diagram of the structure corresponding to different steps of a method for manufacturing a thin film piezoelectric acoustic wave resonator according to Embodiment 4 of the present invention. Figures 10 to 16 , explaining each step in detail.

[0075] refer to Fig.10 , provide a carrier substrate 100, the material of the carrier substrate 100 refers to Example 3, a second reinforcement layer 102 and a second dielectric layer 101 around the second reinforcement layer are formed on the carrier substrate 100, and the materials and formation methods of the second dielectric layer 101 and the second reinforcement layer 102 refer to Example 3.

[0076] Reference Fig.11 A first electrode 201 , a piezoelectric layer 202 and a second electrode 203 are sequentially formed on the second dielectric layer 101 and the second reinforcement layer 102 . The materials and formation methods of the three are the same as those in Example 1 and are not described in detail here.

[0077] refer to Fig.12 A first reinforcement layer 204 is formed on the surface of the second electrode 203. The material and the forming method of the first reinforcement layer refer to Example 3 and are not described here. A second groove 40 is formed on the first reinforcement layer 102. The second groove 40 penetrates the second electrode 203 and the piezoelectric layer 202. The second groove 40 may also penetrate only a portion of the thickness of the piezoelectric layer 202. The structure of the second groove 40 refers to Example 1.

[0078] Reference Figures 13 to 16 , forming a first substrate with a first cavity on the second electrode 203. Specifically, forming a sacrificial layer 206 on the second electrode 203; forming a first substrate to cover the sacrificial layer 206 and the periphery of the sacrificial layer 206; removing the sacrificial layer 206 to form the first cavity 200.

[0079] Specifically, refer to Fig.13 A sacrificial material layer is formed on the surface of the second electrode 203, and the sacrificial material layer is patterned to form a sacrificial layer 206. The sacrificial layer 206 covers the area surrounded by the first reinforcement layer 204 and the second reinforcement layer 102, and fills the second groove. The material of the sacrificial material layer includes phosphosilicate glass, low-temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide or photoresist. Depending on the material, the sacrificial material layer can be formed by a deposition process or a spin coating process.

[0080] refer to Fig.14 , forming a dielectric layer 207, covering the second sacrificial layer 206 and the periphery of the second sacrificial layer, the dielectric layer 207 wraps the second sacrificial layer 206 inside, the material of the dielectric layer 207 includes silicon oxide, silicon nitride, silicon oxynitride and other materials, and the dielectric layer 207 can be formed by deposition. The dielectric layer can be used as a first substrate. In this embodiment, it also includes forming a substrate 208 on the upper surface of the dielectric layer 207, and the substrate 208 can be bonded to the upper surface of the dielectric layer 207 by a bonding process. The purpose of bonding the substrate 208 is to shorten the time of depositing the dielectric layer, because a certain thickness is required above the surface of the sacrificial layer 206 to improve the structural strength of the first substrate. It is slow to form a dielectric layer 207 of a certain thickness by deposition, and the process time is shortened by bonding the substrate 208.

[0081] Reference Fig.15 , remove the carrier substrate 100. The carrier substrate 100 can be removed by grinding, wet etching or etching. This embodiment also includes removing the second dielectric layer 101. After removing the carrier substrate 100, a first groove 41 is formed above the first reinforcement layer 204, and the first groove 41 penetrates the first electrode 201 and the piezoelectric layer 202. The first groove 41 can also only penetrate a portion of the thickness of the piezoelectric layer 202. The structure of the first groove 41 refers to Example 1.

[0082] Reference Fig.16 , remove the sacrificial layer to form the first cavity 200, and a release hole penetrating the first electrode 201, the piezoelectric layer 202 and the second electrode 203 can be formed above the first cavity and outside the first reinforcement layer, and the sacrificial layer is removed through the release hole. According to the selected sacrificial layer material, a corresponding removal method is adopted. For example, when the sacrificial layer material is polyimide or photoresist, an ashing method is adopted to remove it. Specifically, at a temperature of 250 degrees Celsius, oxygen through the release hole reacts chemically with the sacrificial layer material to generate gas substances that volatilize. When the sacrificial layer material is low-temperature silicon dioxide, a hydrofluoric acid solvent is used to react with the low-temperature silicon dioxide to remove it.

[0083] In this embodiment, both the first groove and the first reinforcement layer are formed, and the second groove and the second reinforcement layer are formed. According to the method of this embodiment, only one of the grooves and the corresponding reinforcement layer can also be formed. In this embodiment, the first protrusion and the second protrusion are not formed. It should be understood that the first protrusion and the second protrusion can also be formed using the method of this embodiment. The position and method of formation can refer to Example 3.

[0084] It should be noted that the various embodiments in this specification are described in a related manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiment, since it is basically similar to the structure embodiment, the description is relatively simple, especially for Example 4, the materials, positional relationships and formation methods of the same structure can be referred to the description of Example 3.

[0085] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A thin film bulk acoustic resonator, characterized in that: include: A first substrate, wherein a first cavity is provided on an upper surface of the first substrate; A piezoelectric stack structure is disposed on the upper surface of the first substrate and covers the first cavity, wherein the piezoelectric stack structure comprises a second electrode, a piezoelectric layer and a first electrode stacked in sequence from bottom to top; A groove, comprising a first groove and a second groove, wherein the first groove penetrates the first electrode and extends into the piezoelectric layer or penetrates the piezoelectric layer, and the second groove penetrates the second electrode and extends into the piezoelectric layer or penetrates the piezoelectric layer; A reinforcement layer, disposed on at least one side of the first electrode or the second electrode at the bottom of the groove; The thin film bulk acoustic wave resonator comprises a first groove and a second groove, and the area surrounded by the inner side walls of the first groove and the second groove is an effective resonance area; The projection of the bottom of the groove in the direction of the surface of the piezoelectric layer is located within the range of the projection of the reinforcement layer in the direction of the surface of the piezoelectric layer; A protrusion is arranged at the boundary of the effective resonance area, and the protrusion is arranged opposite to the reinforcement layer; The protrusion has the same height as that of the reinforcement layer.

2. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The reinforcement layer is disposed on a side surface of the first electrode or the second electrode at the bottom of the groove away from the bottom of the groove.

3. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The material of the reinforcement layer includes a conductive material or a dielectric material.

4. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The material of the protrusions is the same as that of the reinforcement layer.

5. A filter comprising at least one thin film bulk acoustic resonator according to any one of claims 1 to 4.

6. A method for manufacturing a thin film bulk acoustic wave resonator, characterized in that: include: providing a carrier substrate, forming a first electrode, a piezoelectric layer, and a second electrode in sequence on the carrier substrate; forming a first substrate with a first cavity on the second electrode; removing the carrier substrate; The thin film bulk acoustic wave resonator includes a second groove and a second reinforcement layer, and forming the second groove and the second reinforcement layer includes: forming a second reinforcement layer on the carrier substrate before forming the first electrode; after forming the second electrode, forming a second groove above a region of the second reinforcement layer that penetrates the second electrode and extends into or penetrates the piezoelectric layer; and / or, The thin film bulk acoustic wave resonator comprises a first groove and a first reinforcement layer, and forming the first groove and the first reinforcement layer comprises: after forming the second electrode, forming the first reinforcement layer on the second electrode; after removing the supporting substrate, forming a first groove above the area of ​​the first reinforcement layer, penetrating the first electrode and extending into the piezoelectric layer or penetrating the piezoelectric layer; Forming the first trench includes: After removing the carrier substrate, forming a first groove penetrating the first electrode and the piezoelectric layer above the region of the first reinforcement layer, and making the projection of the bottom of the first groove in the direction of the surface of the piezoelectric layer be located within the range of the projection of the first reinforcement layer in the direction of the surface of the piezoelectric layer; The thin film bulk acoustic wave resonator comprises a first groove and a second groove, and the area surrounded by the inner side walls of the first groove and the second groove is an effective resonance area; The thin film bulk acoustic wave resonator includes a second groove and a second reinforcement layer, and the method further includes: forming a first protrusion at the boundary of the effective resonance region, the first protrusion protruding from the surface of the first electrode, the first protrusion being arranged opposite to the second reinforcement layer, the first protrusion being formed synchronously with the second reinforcement layer, and forming the first protrusion includes: forming a reinforcement material layer, and patterning the reinforcement material layer to form the second reinforcement layer and the first protrusion; The thin film bulk acoustic wave resonator includes a first groove and a first reinforcement layer. The method also includes: forming a second protrusion at the boundary of the effective resonance area, the second protrusion protruding from the surface of the second electrode, the second protrusion being arranged opposite to the first reinforcement layer, the second protrusion being formed synchronously with the first reinforcement layer, and forming the second protrusion includes: forming a reinforcement material layer, and patterning the reinforcement material layer to form the first reinforcement layer and the second protrusion.

7. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 6, wherein: The forming of a second reinforcement layer on the carrier substrate comprises: forming a second reinforcement material layer on the carrier substrate, patterning the second reinforcement material layer to form the second reinforcement layer, and forming a second dielectric layer on the carrier substrate and around the second reinforcement layer so that the surface of the second dielectric layer is flush with the surface of the second reinforcement layer; After removing the carrier substrate, the method further includes removing the second dielectric layer.

8. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 6, wherein: The forming of a first reinforcement layer on the second electrode comprises: A first reinforcement material layer is formed on the surface of the second electrode by a deposition process, and the first reinforcement material layer is patterned to form the first reinforcement layer.

9. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 6, wherein: Forming the second groove includes: After forming the second electrode, a second groove penetrating the second electrode and the piezoelectric layer is formed above the area of ​​the second reinforcement layer, and the projection of the bottom of the second groove in the direction of the surface of the piezoelectric layer is within the range of the projection of the second reinforcement layer in the direction of the surface of the piezoelectric layer.

10. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 6, wherein: The method of forming a first substrate with a first cavity includes: forming a supporting layer to cover the second electrode; Patterning the support layer to form the first cavity; Providing a substrate, bonding the substrate to the support layer to cover the first cavity, wherein the first substrate includes the support layer and the substrate; or, forming a sacrificial layer on the second electrode; forming a first substrate covering the sacrificial layer and the periphery of the sacrificial layer; The sacrificial layer is removed to form the first cavity.

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