CN112039484A

CN112039484A - Film bulk acoustic resonator and manufacturing method thereof

Info

Publication number: CN112039484A
Application number: CN202010229389.2A
Authority: CN
Inventors: 黄河; 罗海龙; 李伟
Original assignee: China Core Integrated Circuit Ningbo Co Ltd
Current assignee: Ningbo Semiconductor International Corp; China Core Integrated Circuit Ningbo Co Ltd
Priority date: 2020-03-27
Filing date: 2020-03-27
Publication date: 2020-12-04
Also published as: WO2021189965A1

Abstract

The invention provides a film bulk acoustic resonator and a manufacturing method thereof, wherein the film bulk acoustic resonator comprises: the device comprises a bearing substrate, a first substrate and a second substrate, wherein the bearing substrate comprises a first semiconductor layer and a first device layer; a first micro device embedded in the carrier substrate, and at least a portion of the first micro device being located in the first device layer; the dielectric layer is bonded on the first device layer, the dielectric layer surrounds a first cavity, and the surface of the bearing substrate is exposed out of the first cavity; the piezoelectric laminated structure covers the first cavity and comprises a first electrode, a piezoelectric layer and a second electrode which are sequentially laminated from bottom to top; the first cavity is formed in front of the piezoelectric laminated structure and is positioned below the piezoelectric laminated structure; and the first electric connection structure is connected with the first micro device and electrically leads out the first micro device. The invention can improve the integration level of the resonator.

Description

Film bulk acoustic resonator and manufacturing method thereof

Technical Field

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

Background

With the continuous development of wireless communication technology, in order to meet the multifunctional requirements of various wireless communication terminals, terminal devices need to be able to transmit data by using different carrier frequency spectrums, and meanwhile, in order to support a sufficient data transmission rate within a limited bandwidth, strict performance requirements are also provided for a radio frequency system. The radio frequency filter is an important component of a radio frequency system, and can filter out interference and noise outside a communication spectrum so as to meet the requirements of the radio frequency system and a communication protocol on signal to noise ratio. Taking a mobile phone as an example, since each frequency band needs to have a corresponding filter, several tens of filters may need to be arranged in one mobile phone.

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

However, in the cavity type film bulk acoustic resonator manufactured conventionally, because the formation process of the cavity is limited, the micro device cannot be integrated in the substrate below the cavity, and related functions can be realized only by connecting the resonator with an external device, so that the device has a large volume and long lead, the integration level of the resonator is not high, and the requirement for miniaturization of the device cannot be met.

Disclosure of Invention

The invention discloses a film bulk acoustic resonator and a manufacturing method thereof, which can solve the problem of low integration level of the film bulk acoustic resonator.

In order to solve the above technical problem, the present invention provides a film bulk acoustic resonator, including:

the device comprises a bearing substrate, a first substrate and a second substrate, wherein the bearing substrate comprises a first semiconductor layer and a first device layer;

a first micro device embedded in the carrier substrate, and at least a portion of the first micro device being located in the first device layer;

the dielectric layer is bonded on the first device layer, the dielectric layer surrounds a first cavity, and the surface of the bearing substrate is exposed out of the first cavity;

the piezoelectric laminated structure covers the first cavity and comprises a first electrode, a piezoelectric layer and a second electrode which are sequentially laminated from bottom to top; the first cavity is formed in front of the piezoelectric laminated structure and is positioned below the piezoelectric laminated structure;

and the first electric connection structure is connected with the first micro device and electrically leads out the first micro device.

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

providing a temporary substrate;

forming a piezoelectric laminated structure on the temporary substrate, wherein the piezoelectric laminated structure comprises a second electrode, a piezoelectric layer and a first electrode which are sequentially arranged from bottom to top;

forming a dielectric layer to cover the piezoelectric laminated structure;

patterning the dielectric layer to form a first cavity, wherein the first cavity penetrates through the dielectric layer;

providing a bearing substrate, wherein the bearing substrate comprises a first semiconductor layer and a first device layer, a first micro device is embedded in the first surface of the bearing substrate, and the side of the first device layer is the side of the first surface of the bearing substrate;

bonding the bearing substrate to the dielectric layer, covering the first cavity and enabling the first surface to face the first cavity;

removing the temporary substrate;

and forming a first electric connection structure for electrically connecting the first micro device with an external signal.

The invention has the beneficial effects that:

before the bearing substrate is bonded, the first micro device is formed in the bearing substrate in advance, and the manufacture of the first micro device and the manufacture of the resonator are separated, so that the manufacture time is shortened. The micro device can be manufactured independently without being manufactured in the manufacturing process of the resonator, so that the resonator structure is prevented from bearing the process environment when the micro device is manufactured, and the stability of the resonator is improved. Because the bearing substrate is bonded on the dielectric layer in a bonding mode, the first micro device can be formed in the bearing substrate in advance.

Furthermore, the cover substrate is also provided with a micro device, so that the integration level of the resonator is further improved.

Furthermore, the material of the dielectric layer is the same as that of the bonding surface (the first device layer) of the bearing substrate, and the dielectric layer and the bonding surface (the first device layer) can be directly bonded through an atomic bond, so that the bonding strength is improved, and the process flow is simplified.

Furthermore, the first conductive plug and the second conductive plug are located on the same side of the resonator, so that the manufacturing process of the process is facilitated.

Furthermore, the bulge is arranged along the boundary of the effective resonance area, so that the acoustic impedance of the area in which the bulge is arranged and the inside of the effective resonance area are mismatched, the transverse leakage of the acoustic wave is effectively prevented, and the quality factor of the resonator is improved;

furthermore, an effective resonance area of the resonator is defined by the first groove and the second groove, the first groove and the second groove respectively penetrate through the first electrode and the second electrode, and the complete film layer of the piezoelectric layer is not etched, so that the structural strength of the resonator is ensured, and the yield of the resonator is improved.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts.

Fig. 1 shows a schematic structural diagram of a film bulk acoustic resonator of embodiment 1.

Fig. 2 to 11 are schematic structural diagrams corresponding to different steps of a method for manufacturing a thin film bulk acoustic resonator according to embodiment 2.

Description of reference numerals:

100A-a first semiconductor layer; 100B-a first device layer; 1000-a first micro device; 1001-first conductive plug; 101-a bonding layer; 102 a dielectric layer; 103-a first electrode; 104-a piezoelectric layer; 105-a second electrode; 106-a bonding layer; 110 a-a first cavity; 110 b-a second cavity; 120-conductive interconnect structures; 130 a-a first trench; 130 b-a second trench; 141-a first conductive interconnect layer; 142-a first conductive bump; 151-a second conductive interconnect layer; 152-a second conductive bump; 160-an insulating layer; 200A-a second semiconductor layer; 200B-a second device layer; 2000-a second micro device; 2001-a second conductive plug; 40-projection; 300-temporary substrate.

Detailed Description

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

It will 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 can be directly on, adjacent to, connected or coupled to the other elements or layers or intervening elements or layers may be present. 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 are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatial relational terms such as "under," "below," "under," "above," "over," and the like may be used herein for convenience in describing the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "under" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

If the method 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 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

This embodiment provides a thin film bulk acoustic resonator, fig. 1 shows a schematic structural diagram of a thin film piezoelectric acoustic resonator of embodiment 1, please refer to fig. 1, where the thin film bulk acoustic resonator includes:

a carrier substrate including a first semiconductor layer 100A and a first device layer 100B;

a first micro device 1000, the first micro device 1000 being embedded in the carrier substrate with at least a portion of the first micro device 1000 being located in the first device layer 100B;

a dielectric layer 102 bonded to the first device layer 100B, the dielectric layer 102 enclosing a first cavity 110a, the first cavity 110a exposing the surface of the carrier substrate;

the piezoelectric stack structure covers the first cavity 110a, the piezoelectric stack structure comprises a first electrode 103, a piezoelectric layer 104 and a second electrode 105 which are sequentially stacked from bottom to top, and the first cavity 110a is formed in front of the piezoelectric stack structure and located below the piezoelectric stack structure;

a first electrical connection structure connected to the first micro device, the first electrical connection structure for powering the first micro device.

It should be noted that the first cavity 110a is formed before the piezoelectric stack structure and located below the piezoelectric stack structure as follows: in the prior art, a resonator is manufactured by etching a substrate to form a cavity, filling a sacrificial layer material into the cavity, forming a piezoelectric stack structure above the sacrificial layer material and the substrate, releasing the sacrificial layer to form a lower cavity, and suspending the piezoelectric stack structure above the lower cavity. After the piezoelectric laminated structure is formed, a capping layer can be formed on the upper surface of the piezoelectric laminated structure, and a cavity between the capping layer and the piezoelectric laminated structure is an upper cavity. The first cavity of the present invention corresponds to the lower cavity. The carrier substrate of this embodiment is bonded to the dielectric layer after the first cavity is formed. The carrier substrate is required to provide better support for patterning process of the second electrode of the resonator, fabrication and patterning of the bonding layer, fabrication/polishing of the capping layer, or fabrication of the second electrical connection structure. Because the bearing substrate is bonded on the dielectric layer in a bonding mode, the first micro device can be formed in the bearing substrate in advance. The lower cavity is formed by a sacrificial layer method, and a micro device cannot be formed at the bottom of the lower cavity. Before bonding the bearing substrate, the first micro device is formed in the bearing substrate in advance, and the manufacturing time is shortened. The micro device can be manufactured independently without being manufactured in the manufacturing process of the resonator, so that the resonator structure is prevented from bearing the process environment when the micro device is manufactured, and the stability of the resonator is improved.

Specifically, in this embodiment, the carrier substrate includes a first semiconductor layer 100A and a first device layer 100B, the first device layer 100B is close to the side of the first cavity 110A, and the first micro device 1000 is at least partially formed in the first device layer 100B. The first micro device 1000 includes: a diode, a triode, a MOS transistor, an electrostatic discharge protection device, a resistor, a capacitor or an inductor. When the first micro device 1000 is a resistor, a capacitor, or an inductor, the first micro device 1000 may be entirely located in the device layer 100B, and when the first micro device 1000 is a triode or a MOS transistor, the source and the drain thereof may be located in the first semiconductor layer 100A.

The material of the first semiconductor layer 100A includes silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), other III/V compound semiconductors, or the like. The material of the first device layer 100B includes silicon oxide, silicon nitride, silicon oxynitride, and silicon carbonitride. The first device layer 100B and the dielectric layer 102 are bonded. The material of the dielectric layer 102 may be any suitable dielectric material including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or ethyl silicate. When the materials of the first device layer 100B and the dielectric layer 102 are the same, atomic bonding may be used to directly perform bonding. When the materials of the first device layer 100B and the dielectric layer 102 are different, a bonding layer may be formed on a bonding surface of the two, and the materials of the bonding layer include: silicon oxide, silicon nitride, polysilicon, ethyl silicate, or an organic cured film. In this embodiment, the first device layer 100B and the dielectric layer are both made of silicon oxide, and are bonded by using an atomic bond, so that the bonding structure is strong and the process flow is simple. When bonding is performed through the bonding layer, a bonding layer structure is formed between the dielectric layer 101 and the carrier substrate. The materials of the dielectric layer and the bonding layer may be the same or different.

In this embodiment, the first cavity 110a is a closed cavity, and the first cavity 110a may be formed by etching the dielectric layer 102 through an etching process. The bottom surface of the first cavity 110a is rectangular, but in other embodiments of the present invention, the shape of the first cavity 110a on the bottom surface of the first electrode 103 may also be circular, elliptical, or polygonal other than rectangular, such as pentagonal, hexagonal, etc.

A piezoelectric stack structure is arranged above the first cavity 110a, and the piezoelectric stack structure sequentially includes the first electrode 103, the piezoelectric layer 104, and the second electrode 105 from bottom to top. A first electrode 103 is located on the dielectric layer 102, a piezoelectric layer 104 is located on the first electrode 103, and a second electrode 105 is located on the piezoelectric layer 104. The first electrode 103, the piezoelectric layer 104 and the second electrode 105 above the first cavity 110a are provided with an overlapping area in a direction perpendicular to the carrier substrate 100 as an effective resonance area, and the boundary of the effective resonance area is located in an area surrounded by the first cavity 110 a. The shape of the effective resonance region is an irregular polygon, such as a pentagon, a hexagon, etc., where there are no parallel opposite sides.

In this embodiment, the piezoelectric layer 104 covers the first cavity 110a, and covering the first cavity 110a should be understood as the piezoelectric layer 104 is a complete film layer and is not etched. It is not intended that the piezoelectric layer 104 completely cover the first cavity 110a to form a sealed cavity. Of course, the piezoelectric layer 104 can completely cover the first cavity 110a, forming a sealed cavity. The piezoelectric layer can be guaranteed to have certain thickness without being etched, so that the resonator has certain structural strength. The yield of the resonator is improved.

In one embodiment, an etch stop layer is further disposed between the dielectric layer 102 and the first electrode 103, and the material of the etch stop layer includes, but is not limited to, silicon nitride (Si3N4) and silicon oxynitride (SiON). The etching stop layer can be used for improving the structural stability of the finally manufactured film bulk acoustic resonator on one hand, and on the other hand, the etching stop layer has a lower etching rate compared with the dielectric layer 102, so that over-etching can be prevented in the process of etching the dielectric layer 102 to form the first cavity 110a, the surface of the first electrode 103 below the etching stop layer is protected from being damaged, and the performance and the reliability of the device are improved.

In this embodiment, a bonding layer 106 is included above the piezoelectric stack structure, the bonding layer 106 encloses a second cavity 110b, the second cavity 110b exposes a surface of the piezoelectric stack structure, and the second cavity 110b is located above the first cavity 110 a. A cover substrate is further included and disposed on the bonding layer 106 and covers the second cavity 110 b. In this embodiment, a second micro device 2000 is embedded in the cover substrate near the second cavity 110 b.

In this embodiment, the capping substrate has a double-layer structure including a second semiconductor layer 200A and a second device layer 200B. The second device layer 100B is adjacent to the second cavity 110B, and the first micro device 1000 is at least partially formed in the second device layer 200B. The type of the second micro device 1000 and the positional relationship with the capping substrate refer to the type of the first micro device 1000 and the positional relationship with the carrier substrate, the material for the second semiconductor layer 200A refers to the material for the first semiconductor layer 100A, and the material for the second device layer 200B refers to the material for the first device layer 100B, which are not repeated herein. The bonding layer 106 may be made of a conventional bonding material, such as silicon oxide, silicon nitride, silicon oxynitride, ethyl silicate, etc., or may be an adhesive such as a photo-curing material or a thermosetting material, such as a Die Attach Film (DAF) or a Dry Film (Dry Film), and the fabrication and patterning processes are relatively simple. The material of the bonding layer and the material of the cover substrate 200 may be the same, and they are an integral structure, and the second cavity 110b is formed by forming a space in the film layers (forming the bonding layer 106 and the cover substrate 200).

In order to supply power to the first micro device 1000 and the second micro device 2000, the resonator further includes a first electrical connection structure connected to the first micro device 1000 and a second electrical connection structure connected to the second micro device 2000, in this embodiment, the first electrical connection structure is a first conductive plug 1001, and the second electrical connection structure is a second conductive plug 2001.

In this embodiment, a first conductive plug 1001 extends from the bottom surface of the carrier substrate to the first micro device 1000. A second conductive plug 2001 extends from the bottom surface of the carrier substrate to the second micro device 2000.

In another embodiment, a first conductive plug may extend from a top surface of the capping substrate to the first micro device. A second conductive plug also extends from the top surface of the capping substrate to the second micro device. In both cases, the two conductive plugs are electrically connected to the micro device from the same side of the resonator. The main consideration is that the opposite sides of the conductive plug need to have a certain strength support when the conductive plug is manufactured. When the conductive plug is manufactured, one side (the bearing substrate or the cover substrate) for manufacturing the conductive plug needs to be thinned, the thickness of the side is about 100 micrometers, the opposite side (the bearing substrate or the cover substrate) for manufacturing the conductive plug does not need to be thinned, and the thickness of the side is about hundreds of micrometers, so that certain strength support is provided for the manufacturing process. Of course, the first and second conductive plugs may be disposed on opposite sides of the resonator, as process conditions allow. In one embodiment, a third electrical connection structure, such as a third conductive plug, may also be included to electrically connect the first micro device and the second micro device.

In this embodiment, the resonator further includes a first electrode lead-out portion for leading an electrical signal to the first electrode 103 in the effective resonance region, and a second electrode lead-out portion for leading an electrical signal to the second electrode 105 in the effective resonance region. When the first electrode 103 and the second electrode 105 are energized, a pressure difference is generated between the upper surface and the lower surface of the piezoelectric layer 104, and standing wave oscillation is formed. The conductive interconnect structure 120 is used to short the first and second electrodes outside the active resonance area. As can be seen from the figure, the effective resonance region also includes a region where the piezoelectric layer, the first electrode, and the second electrode overlap each other in a direction perpendicular to the piezoelectric layer. When the first electrode and the second electrode are electrified, the pressure difference can be generated above and below the surface of the piezoelectric layer outside the effective resonance area, standing wave oscillation is also generated, however, the standing wave oscillation outside the effective resonance area is not expected, the first electrode and the second electrode outside the effective resonance area are in short circuit, the voltage of the piezoelectric layer outside the effective resonance area is consistent, standing wave oscillation cannot be generated outside the effective resonance area, and the Q value of the resonator is improved. The specific structures of the first electrode lead-out portion, the second electrode lead-out portion, and the conductive interconnection structure 120 are as follows:

the first electrode lead-out portion includes:

a first via 140, wherein the first via 140 penetrates through the lower layer structure of the first electrode 103 outside the effective resonance region, and exposes the first electrode 103; a first conductive interconnection layer 141 covering an inner surface of the first via hole 140 and a portion of the surface of the carrier substrate 100 at the periphery of the first via hole 140, and connected to the first electrode 103; an insulating layer 160 covering the first conductive interconnect layer 141 and the surface of the carrier substrate 100; and a conductive bump 142 disposed on the surface of the carrier substrate 100 and electrically connected to the first conductive interconnection layer 141.

The second electrode lead-out portion includes:

a second via 150, the second via 150 penetrating through the lower structure of the first electrode 103 outside the effective resonance region to expose the first electrode 103; a second conductive interconnection layer 151 covering an inner surface of the second via 150 and a portion of the surface of the carrier substrate 100 around the second via 150, and connected to the first electrode 103; an insulating layer 160 covering the second conductive interconnection layer 151 and the surface of the carrier substrate 100; and a second conductive bump 152 disposed on the surface of the carrier substrate 100 and electrically connected to the second conductive interconnection layer 151.

In this embodiment, a protrusion 40 is disposed at the boundary of the effective resonance region, and the protrusion 40 is disposed on the upper surface or the lower surface of the piezoelectric stack structure; or, the protrusion 40 is partially disposed on the upper surface of the piezoelectric stack structure, and partially disposed on the lower surface of the piezoelectric stack structure.

In this embodiment, the protrusions 40 are all located on the lower surface of the piezoelectric stack. All located on the side of the first cavity 110 a. The area surrounded by the protrusion 40 is an effective resonance area, and the outside of the protrusion 40 is an ineffective resonance area. The first electrode 103, the piezoelectric layer 104 and the second electrode 105 in the effective resonance region overlap each other in a direction perpendicular to the carrier substrate 100. In other embodiments, the protrusion 40 may be located entirely on the upper surface of the piezoelectric stack, on the side facing away from the first cavity 110 a. The protrusion 40 may also be partially disposed on the upper surface of the piezoelectric stack and partially disposed on the lower surface of the piezoelectric stack.

In this embodiment, the projection of the protrusion 40 on the carrier substrate 100 forms a closed ring shape, such as a closed irregular polygon, a circle, or an ellipse. The bulge 40 enables the acoustic impedance of the effective resonance area inside the bulge 40 to be mismatched with that of the area where the bulge 40 is located, so that the transverse leakage of sound waves can be effectively prevented, and the quality factor of the resonator is improved. In other embodiments, the projection of the protrusions 40 onto the carrier substrate 100 may not be a completely closed figure. It should be understood that when the projection of the protrusion 40 on the carrier substrate 100 is a closed figure, it is more advantageous to prevent the lateral leakage of the acoustic wave.

The material of the protrusion 40 may be a conductive material or a dielectric material, and when the material of the protrusion 40 is a conductive material, the material may be the same as the material of the first electrode 103 or the second electrode 105, and when the material of the protrusion 40 is a dielectric material, the material may be any one of silicon oxide, silicon nitride, silicon oxynitride, or silicon carbonitride, but is not limited to the above materials.

In this embodiment, the surface of the piezoelectric stack further includes a first groove 130a and a second groove 130b, the first groove 130a is located on the lower surface of the piezoelectric stack and on the side of the first cavity 110a, penetrates through the first electrode 103, and surrounds the periphery of the area where the protrusion 40 is located. The second groove 130b is located on the upper surface of the piezoelectric stack structure, penetrates through the second electrode 105, and surrounds the periphery of the area where the protrusion 40 is located. Two ends of the first trench 130a are disposed opposite to two ends of the second trench 130b, so that the first trench 130a and the second trench 130b meet at two intersections of the projection of the carrier substrate 100 or are provided with gaps. In this embodiment, the projection of the protrusion 40 on the piezoelectric layer 104 is a closed polygon, and the inner edges of the first groove 130a and the second groove 130b are disposed along the outer boundary of the protrusion 40, that is, the outer boundary of the protrusion 40 is overlapped with the inner edges of the first groove 130a and the second groove 130 b. The projections of the first groove 130a and the second groove 130b on the carrier substrate 100 are closed figures, and the shapes of the closed figures are consistent with the shapes of the projections 40 on the carrier substrate 100, and are positioned at the periphery of the projection formed by the projections 40.

It should be understood that the protrusion 40 is annular (when the protrusion 40 is located entirely on the lower or upper surface of the piezoelectric stack, the protrusion 40 forms an annular shape; when the protrusion 40 is located on both surfaces of the piezoelectric stack, the projections of the two portions of the protrusion together form an overall annular shape). When the protrusion 40 is located on the upper surface or the lower surface of the piezoelectric stack, the first groove 130a surrounds a portion of the outer periphery of the protrusion 40, and the second groove 130b surrounds the remaining portion of the outer periphery of the protrusion 40 (in this case, the second groove 130b surrounds the outer periphery of the protrusion 40, which means the outer periphery of the piezoelectric stack surface surrounding the area of the protrusion 40, and does not directly surround the outer periphery of the protrusion 40). When the protrusion 40 is partially disposed on the upper surface of the piezoelectric stack and partially disposed on the lower surface of the piezoelectric stack, the first groove 130a may surround the outer circumference of the protrusion 40 on the lower surface of the piezoelectric stack, and the second groove 130b may surround the outer circumference of the protrusion 40 on the upper surface of the piezoelectric stack. However, the present invention is not limited thereto as long as the first groove 130a and the second groove 130b are fitted to each other around the outer circumference of the area where the protrusion 40 is located.

The protrusion 40 mismatches the acoustic impedance of the inner region of the protrusion to the acoustic impedance of the region in which the protrusion is located, defining the boundary of the effective resonance region of the resonator. The first trench 130a and the second trench 130b separate the first electrode 103 and the second electrode 105, respectively, so that the resonator cannot satisfy an operating condition (the operating condition is that the first electrode 103, the piezoelectric layer 104, and the second electrode 105 overlap each other in the thickness direction), further defining a boundary of an effective resonance region of the resonator. The protrusion 40 makes the acoustic impedance mismatched by adding the mass block, the first groove 130a and the second groove 130b make the electrode end surface contact with air, so that the acoustic impedance is mismatched, and both the first groove 130a and the second groove prevent the transverse wave from leaking, thereby improving the Q value of the resonator. Of course, in other embodiments, only the first trench 130a or the second trench 130b may be separately disposed, and since the first electrode 103 and the second electrode 105 need to introduce an electrical signal, the first trench 130a or the second trench 130b is not suitable to form a closed ring shape, and at this time, the first trench 130a or the second trench 130b cannot completely surround the region where the protrusion 40 is located. The first trench 130a or the second trench 130b may be formed in a nearly closed loop shape, and an open region is used for introducing an electrical signal. The arrangement mode can simplify the process flow and reduce the cost of the resonator.

In this embodiment, the conductive interconnection structure 120 is further included, and the conductive interconnection structure 120 includes two parts, one of which is disposed in the outer region of the second trench 130b, connects the first electrode 103 and the second electrode 105, and is electrically connected to the first electrode lead-out portion through the first electrode 103. The other part of the conductive interconnection structure 120 is disposed in the outer region of the first trench 130a, connects the first electrode 103 and the second electrode 105, and is electrically connected to the second electrode lead-out portion through the first electrode 103. The two portions of the conductive interconnect structure 120 are each provided with a region covering a portion of the surface of the second electrode 105, which increases the contact area with the second electrode 105, reduces the contact resistance, and prevents local high temperatures caused by excessive current.

The second electrode lead-out portion is not directly electrically connected to the second electrode, but is connected to the first electrode outside the effective resonance region, and is electrically connected to the second electrode of the effective resonance region through the conductive interconnection structure 120. It can be seen that the first electrode lead-out portion and the second electrode lead-out portion are identical in structure, but are disposed at different positions, the first electrode lead-out portion is electrically connected to the first electrode inside the effective resonance region to supply power to the first electrode inside the effective resonance region, and the first electrode lead-out portion is electrically connected to the second electrode outside the effective resonance region through the first electrode outside the effective resonance region and the conductive interconnection structure 120, and is not connected to the second electrode inside the effective resonance region. In a similar way, the second electrode leading-out part is connected with the first electrode outside the effective resonance area and the second electrode inside the effective resonance area, so that power supply for the second electrode inside the effective resonance area is realized.

Example 2

Embodiment 2 provides a method for manufacturing a film bulk acoustic resonator, including the steps of:

s01: providing a temporary substrate;

s02: forming a piezoelectric laminated structure on the temporary substrate, wherein the piezoelectric laminated structure comprises a second electrode, a piezoelectric layer and a first electrode which are sequentially arranged from bottom to top;

s03: forming a dielectric layer to cover the piezoelectric laminated structure;

s04: patterning the dielectric layer to form a first cavity, wherein the first cavity penetrates through the dielectric layer;

s05: providing a bearing substrate, wherein the bearing substrate comprises a first semiconductor layer and a first device layer, a first micro device is embedded in the first surface of the bearing substrate, and the side of the first device layer is the side of the first surface of the bearing substrate;

s06: bonding the bearing substrate to the dielectric layer, covering the first cavity and enabling the first surface to face the first cavity;

s07: removing the temporary substrate;

s08: and forming a first electric connection structure for electrically connecting the first micro device with an external signal.

It should be noted that S0N is not used to limit the order of the steps. Fig. 2 to 11 are schematic structural diagrams illustrating different stages of a method for manufacturing a thin film piezoelectric acoustic resonator according to embodiment 2 of the present invention, and please refer to fig. 2 to 11 to describe in detail the steps.

Referring to fig. 2, step S01 is performed: a temporary substrate 300 is provided.

The temporary substrate 300 may be at least one of the following mentioned 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 may be a ceramic substrate such as alumina, a quartz or glass substrate, or the like.

Referring to fig. 3, step S02 is performed: forming a piezoelectric laminated structure on the temporary substrate 300, wherein the piezoelectric laminated structure comprises a second electrode 105, a piezoelectric layer 104 and a first electrode 103 which are sequentially arranged from bottom to top.

The material of the second electrode 105 and the first electrode 103 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 105 and the first electrode 103 may be formed by physical vapor deposition such as magnetron sputtering or evaporation, or by chemical vapor deposition. As a material of the piezoelectric layer 104, a piezoelectric material having a wurtzite crystal structure such as aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), Quartz (Quartz), potassium niobate (KNbO3), or lithium tantalate (LiTaO3), or a combination thereof can be used. When the piezoelectric layer 104 comprises aluminum nitride (AlN), the piezoelectric layer 104 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 104 includes aluminum nitride (AlN), the piezoelectric layer 104 may further include a transition metal, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). Piezoelectric layer 104 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 this embodiment, the second electrode 105 and the first electrode 103 are made of molybdenum metal (Mo), and the piezoelectric layer 104 is made of aluminum nitride (AlN).

Referring to fig. 4, step S03 is performed: a dielectric layer 102 is formed overlying the piezoelectric stack.

The dielectric layer 102 is formed by physical vapor deposition or chemical vapor deposition. The material of the dielectric layer 102 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.

Referring to fig. 5, step S05 is performed: and patterning the dielectric layer 102 to form a first cavity 110a, wherein the first cavity 110a penetrates through the dielectric layer 102.

The dielectric layer 102 is etched by an etching process to form a first cavity 110a, and the first electrode layer 103 at the bottom is exposed. The etching process may be a wet etching or a dry etching process including, but not limited to, Reactive Ion Etching (RIE), ion beam etching, plasma etching. 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 the thickness of the formed dielectric layer 102. 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.

Referring to fig. 6, step S05 is performed: providing a bearing substrate, wherein the bearing substrate comprises a first semiconductor layer 100A and a first device layer 100B, a first micro device 1000 is embedded in the first surface of the bearing substrate, and the side of the first device layer 100B is the side of the first surface of the bearing substrate. The material of the first semiconductor layer 100A, the material of the first device layer 100B, the type of the first micro device 1000, and the structural relationship with the carrier substrate refer to the description of embodiment 1, and are not repeated herein.

Referring to fig. 7, step S06 is performed: and bonding the bearing substrate to the dielectric layer 102, covering the first cavity 110a, and enabling the first surface to face the first cavity 110 a. The materials of the dielectric layer and the bonding mode of the dielectric layer and the carrier substrate are described with reference to embodiment 1.

Referring to fig. 8, step S07 is performed: and removing the temporary substrate. The method of removing the temporary substrate may employ mechanical grinding.

Referring to fig. 9 and 10, in this embodiment, before forming the first electrical connection structure and connecting the first micro device, the method further includes: forming a bonding layer 106 on the piezoelectric stack structure, wherein the bonding layer 106 encloses a second cavity 110b, the second cavity 110b exposes a surface of the piezoelectric stack structure, and the second cavity 110b is located above the first cavity 110 a. Providing a cover substrate, wherein the cover substrate comprises a second semiconductor layer 200A and a second device layer 200B, a second micro device 2000 is embedded in the first surface of the cover substrate, and the side of the second device layer 200B is the side of the first surface of the cover substrate. The capping substrate is disposed on the bonding layer 106, covering the second cavity 110b, and facing the first surface of the capping substrate toward the second cavity 110 b. The material of the bonding layer 106, the material of the second semiconductor layer 200A, the material of the second device layer 200B, the type of the second micro device 2000, and the structural relationship with the capping substrate refer to the description of embodiment 1, and are not repeated herein.

Referring to fig. 11, step S08 is performed: and forming a first electric connection structure for electrically connecting the first micro device with an external signal. The embodiment further includes: and forming a second electric connection structure for electrically connecting the second micro device with an external signal. The first and second electrical connection structures are a first conductive plug 1001 and a second conductive plug 2001, respectively. In this embodiment, forming the first conductive plug 1001 and the second conductive plug 2001 includes: a first through hole (not shown) penetrating through the carrier substrate and a second through hole (not shown) penetrating through the carrier substrate and the carrier substrate upper structure (the upper structure in this embodiment includes the dielectric layer 102, the piezoelectric stack structure, the bonding layer 106, and a portion of the second device layer 200B) are formed from the carrier substrate side, the first through hole exposes the first micro device 1000, the second through hole exposes the second micro device 2000, and a conductive material is formed in the first through hole 1000 and the second through hole 2000 to form the first conductive plug 1001 and the second conductive plug 2001. The first and second vias may be formed using a dry etching process, and the conductive material formed in the first and second vias may be formed using an electroplating or electroless plating process.

In another embodiment, forming first and second

conductive plugs

1001 and 2001 includes: and forming a third through hole penetrating through the cover substrate and a fourth through hole penetrating through the cover substrate and the structure below the cover substrate from the side of the cover substrate, wherein the third through hole exposes the second micro device, the fourth through hole exposes the first micro device, and a conductive material is formed in the third through hole and the fourth through hole to form the second conductive plug and the first conductive plug.

The two conductive plugs are formed on the same side of the resonator (the side on which the carrier substrate is located or the side on which the cover substrate is located), and the reason for this arrangement is described with reference to embodiment 1. The conductive plug is formed in front of the side of the bearing substrate, and the bearing substrate is thinned by taking the cover base plate as a support; the conductive plug is formed in front of the side of the cover base plate, and the cover base plate is thinned by taking the bearing substrate as a support.

In this embodiment, a first electrode lead-out portion and a second electrode lead-out portion are further formed, the first electrode lead-out portion is connected to the first electrode 103, the second electrode lead-out portion is connected to the second electrode 105, and the first electrode lead-out portion and the second electrode lead-out portion are located on the side of the carrier substrate. When the first conductive plug and the second conductive plug are located on the side where the cover substrate is located, the first electrode lead-out portion and the second electrode lead-out portion are preferably located on the side where the cover substrate is located.

Wherein forming the first electrode lead-out portion includes:

forming a through hole penetrating through a lower layer structure of the first electrode 103 by an etching process, wherein the through hole exposes the first electrode 103, forming a first conductive interconnection layer 141 in the through hole by an electroplating process or a physical vapor deposition process, and the first conductive interconnection layer 141 covers the inner surface of the through hole and a part of the surface of the carrier substrate 100 at the periphery of the through hole and is connected with the first electrode 103; forming an insulating layer 160 on the surface of the first conductive interconnection layer 141 through a deposition process; a first conductive bump 142 is formed on the surface of the carrier substrate, and the first conductive bump 142 is electrically connected to the first conductive interconnection layer 141.

Forming the second electrode lead-out portion includes:

forming a through hole penetrating through the lower layer structure of the first electrode 103 by an etching process, wherein the through hole exposes the second electrode 105, forming a second conductive interconnection layer 151 in the through hole by a deposition process or an electroplating process, wherein the second conductive interconnection layer 151 covers the inner surface of the through hole and part of the surface of the bearing substrate at the periphery of the through hole and is connected with the second electrode 105; forming an insulating layer 160 on the surface of the second conductive interconnection layer 151 through a deposition process; a second conductive bump 152 is formed on the surface of the carrier substrate 100, and the second conductive bump 152 is electrically connected to the second conductive interconnection layer 151.

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

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

Claims

1. A thin film bulk acoustic resonator, comprising:

the piezoelectric laminated structure covers the first cavity and comprises a first electrode, a piezoelectric layer and a second electrode which are sequentially laminated from bottom to top;

2. The thin film bulk acoustic resonator of claim 1, further comprising:

the junction layer is arranged above the piezoelectric laminated structure, a second cavity is surrounded by the junction layer, the surface of the piezoelectric laminated structure is exposed out of the second cavity, and the projection of the second cavity and the projection of the first cavity on the piezoelectric laminated structure are overlapped;

and the sealing cover substrate is arranged on the bonding layer and covers the second cavity.

3. The thin film bulk acoustic resonator of claim 2, wherein the capping substrate comprises a second semiconductor layer and a second device layer, the second device layer being adjacent to a side of the second cavity; further comprising:

a second micro device embedded in the capping substrate, at least a portion of the second micro device being located in the second device layer;

and the second electric connection structure is connected with the second micro device and electrically leads out the second micro device.

4. The thin film bulk acoustic resonator of claim 1, wherein the first electrical connection structure comprises:

a first conductive plug extending from a bottom surface of the carrier substrate to the first micro device or; the first conductive plug extends from the top surface of the capping substrate to the first micro device.

5. The film bulk acoustic resonator of claim 3, wherein the second electrical connection structure comprises:

a second conductive plug extending from a bottom surface of the carrier substrate to the first micro device or; the second conductive plug extends from the top surface of the capping substrate to the second micro device.

6. The thin film bulk acoustic resonator of claim 3, further comprising a third electrical connection structure connecting the first micro device and the second micro device.

7. The thin film bulk acoustic resonator of claim 3, wherein the first micro device and/or the second micro device comprises:

a diode, a triode, a MOS transistor, an electrostatic discharge protection device, a resistor, a capacitor or an inductor.

8. The thin film bulk acoustic resonator of claim 1, wherein the material of the first device layer comprises: silicon oxide, silicon nitride, silicon oxynitride, or silicon carbonitride.

9. The film bulk acoustic resonator of claim 1, wherein the material of the dielectric layer comprises silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or ethyl silicate.

10. The film bulk acoustic resonator of claim 1, wherein the dielectric layer and the first device layer are made of the same material, and the bonding manner comprises: the atoms are bonded.

11. The film bulk acoustic resonator of claim 1, further comprising a bonding layer disposed between the dielectric layer and the carrier substrate.

12. The film bulk acoustic resonator of claim 11, wherein the bonding layer comprises a material comprising: silicon oxide, silicon nitride, polysilicon, ethyl silicate, or an organic cured film.

13. The film bulk acoustic resonator of claim 12, wherein the dielectric layer and the bonding layer are of the same material.

14. The thin film bulk acoustic resonator of claim 1, further comprising:

a first trench located inside an area surrounded by the first cavity, penetrating the first electrode, or penetrating the first electrode and the piezoelectric layer;

the second groove is positioned in an area enclosed by the second cavity, is arranged opposite to the first groove in the transverse direction, and penetrates through the second electrode or penetrates through the second electrode and the piezoelectric layer;

the first groove and the second groove are connected or provided with a gap at two junctions of the projection of the bearing substrate.

15. The film bulk acoustic resonator according to claim 1, wherein an area where the first electrode, the piezoelectric layer, and the second electrode overlap with each other in a direction perpendicular to the carrier substrate is an effective resonance area, a boundary of the effective resonance area is located in an area surrounded by the first cavity, a protrusion is provided at the boundary of the effective resonance area, and the protrusion is provided on an upper surface or a lower surface of the piezoelectric laminated structure; or the like, or, alternatively,

the protruding part is arranged on the upper surface of the piezoelectric laminated structure, and the part is arranged on the lower surface of the piezoelectric laminated structure.

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

providing a temporary substrate;

forming a dielectric layer to cover the piezoelectric laminated structure;

providing a carrier substrate, wherein the carrier substrate comprises a first semiconductor layer and a first device layer, a first micro device is embedded in the carrier substrate, and at least part of the first micro device is positioned in the first device layer;

bonding the first device layer of the bearing substrate to the dielectric layer and covering the first cavity;

removing the temporary substrate;

and forming a first electric connection structure to lead out the first micro device electrically.

17. The method of manufacturing a thin film bulk acoustic resonator according to claim 16, further comprising, after removing the temporary substrate and before forming the first electrical connection structure:

forming a bonding layer on the piezoelectric laminated structure, wherein the bonding layer surrounds a second cavity, the second cavity exposes the surface of the piezoelectric laminated structure, and the second cavity is positioned above the first cavity;

and providing a cover substrate, arranging the cover substrate on the junction layer, covering the second cavity, and enabling the first surface of the cover substrate to face the second cavity.

18. The method of manufacturing a thin film bulk acoustic resonator according to claim 17, wherein the step of embedding a second micro device in the first surface of the cover substrate and the step of disposing the cover substrate on the bonding layer further comprises: and forming a second electric connection structure for electrically connecting the second micro device with an external signal.

19. The method of manufacturing a thin film bulk acoustic resonator according to claim 18, wherein the first electrical connection structure is a first conductive plug, the second electrical connection structure is a second conductive plug, and forming the first electrical connection structure and the second electrical connection structure includes:

forming a first through hole penetrating through the bearing substrate and a second through hole penetrating through the bearing substrate and the bearing substrate upper structure from the bearing substrate side, wherein the first through hole exposes the first micro device, the second through hole exposes the second micro device, and a conductive material is formed in the first through hole and the second through hole to form the first conductive plug and the second conductive plug.

20. The method of manufacturing a thin film bulk acoustic resonator according to claim 18, wherein the first electrical connection structure is a first conductive plug, the second electrical connection structure is a second conductive plug, and forming the first electrical connection structure and the second electrical connection structure includes:

and forming a third through hole penetrating through the cover substrate and a fourth through hole penetrating through the cover substrate and the structure below the cover substrate from the side of the cover substrate, wherein the third through hole exposes the second micro device, the fourth through hole exposes the first micro device, and a conductive material is formed in the third through hole and the fourth through hole to form the second conductive plug and the first conductive plug.

21. The method of manufacturing a thin film bulk acoustic resonator according to claim 19 or 20, further comprising: and forming a first electrode leading-out part and a second electrode leading-out part, wherein the first electrode leading-out part is connected with the first electrode, the second electrode leading-out part is connected with the second electrode, and leading-out ends of the first electrode leading-out part, the second conductive plug and the first conductive plug are all positioned on the side where the cover substrate is positioned or the side where the bearing substrate is positioned.

22. The method of manufacturing a thin film bulk acoustic resonator according to claim 16, further comprising, after forming the first cavity and before bonding the carrier substrate:

patterning the first electrode, or the first electrode and the piezoelectric layer, to form part of the boundary of the effective resonance region;

after removing the temporary substrate, the method further comprises:

patterning the second electrode, or the second electrode and the piezoelectric layer, to form another part of a boundary of an effective resonance area, where the boundary of the effective resonance area is located in an area where projections of the first cavity and the second cavity overlap in the direction of the piezoelectric layer.

23. The method of manufacturing a thin film bulk acoustic resonator of claim 18, wherein the first micro device and/or the second micro device comprises:

24. The method of manufacturing a thin film bulk acoustic resonator according to claim 16, wherein the material of the first device layer includes: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride.

25. The method of manufacturing a thin film bulk acoustic resonator according to claim 24, wherein a material of the dielectric layer is the same as a material of the first device layer, and bonding the carrier substrate on the dielectric layer comprises: bonded directly through an atomic bond.

26. The method of manufacturing a thin film bulk acoustic resonator according to claim 16, wherein bonding the carrier substrate on the dielectric layer comprises:

and forming a bonding layer on the surface of the dielectric layer, and bonding the dielectric layer and the bearing substrate through the bonding layer, wherein the dielectric layer and the bonding layer are made of the same material.