A thin film bulk acoustic resonator and a method for manufacturing the same

Abstract

The present invention provides a thin film bulk acoustic wave resonator and a manufacturing method thereof, wherein the thin film bulk acoustic wave resonator comprises: a carrier substrate, the carrier substrate comprises a first semiconductor layer and a first device layer; a first micro-device, the first micro-device is embedded in the carrier substrate, and at least part of the first micro-device is located in the first device layer; a dielectric layer, bonded to the first device layer, the dielectric layer encloses a first cavity, and the first cavity exposes the surface of the carrier substrate; a piezoelectric stack structure, covering the first cavity, the piezoelectric stack structure comprises a first electrode, a piezoelectric layer, and a second electrode stacked in sequence from bottom to top; the first cavity is formed before the piezoelectric stack structure and is located below the piezoelectric stack structure; a first electrical connection structure, connecting the first micro-device and electrically leading the first micro-device out. The present invention can improve the integration of the resonator.

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 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, due to the limitations of the cavity formation process, traditionally manufactured cavity-type thin film bulk acoustic wave resonators cannot integrate micro devices in the substrate below the cavity. The resonator can only be connected to external devices to achieve related functions, resulting in large device size and long leads, making the resonator's integration level low and unable to meet the needs of device miniaturization. Summary of the invention

[0005] The invention discloses a thin film bulk acoustic wave resonator and a manufacturing method thereof, which can solve the problem of low integration of the thin film bulk acoustic wave resonator.

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

[0007] A carrier substrate, the carrier substrate comprising a first semiconductor layer and a first device layer;

[0008] a first micro device, wherein the first micro device is embedded in the carrier substrate, and at least a portion of the first micro device is located in the first device layer;

[0009] a dielectric layer bonded to the first device layer, the dielectric layer enclosing a first cavity, the first cavity exposing a surface of the carrier substrate;

[0010] A piezoelectric stack structure covers the first cavity, wherein the piezoelectric stack structure includes a first electrode, a piezoelectric layer, and a second electrode stacked in sequence from bottom to top; the first cavity is formed before the piezoelectric stack structure and is located below the piezoelectric stack structure;

[0011] The first electrical connection structure is connected to the first micro-device to electrically lead out the first micro-device.

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

[0013] providing a temporary substrate;

[0014] forming a piezoelectric stack structure on the temporary substrate, wherein the piezoelectric stack structure comprises a second electrode, a piezoelectric layer, and a first electrode arranged in sequence from bottom to top;

[0015] forming a dielectric layer to cover the piezoelectric stack structure;

[0016] Patterning the dielectric layer to form a first cavity, wherein the first cavity penetrates the dielectric layer;

[0017] Providing a carrier substrate, the carrier substrate comprising a first semiconductor layer and a first device layer, a first micro-device being embedded in a first surface of the carrier substrate, and a side where the first device layer is located is a side where the first surface of the carrier substrate is located;

[0018] Bonding the carrier substrate to the dielectric layer to cover the first cavity, with the first surface facing the first cavity;

[0019] removing the temporary substrate;

[0020] A first electrical connection structure is formed to electrically connect the first micro device to an external signal.

[0021] The beneficial effects of the present invention are:

[0022] Before bonding the carrier substrate, the first micro-device is pre-formed in the carrier substrate, which is separated from the production of the resonator, thereby shortening the process time. The micro-device can be produced separately, without being produced in the resonator manufacturing process, so as to avoid the resonator structure being subjected to the process environment when producing the micro-device, thereby improving the stability of the resonator. Since the structure bonds the carrier substrate to the dielectric layer by bonding, it is possible to pre-form the first micro-device in the carrier substrate.

[0023] Furthermore, micro devices are also formed in the cover substrate, further improving the integration of the resonator.

[0024] Furthermore, the dielectric layer and the bonding surface of the carrier substrate (first device layer) are made of the same material and can be directly bonded via atomic bonds, thereby increasing the bonding strength and simplifying the process flow.

[0025] Furthermore, the first conductive plug and the second conductive plug are located on the same side of the resonator, which facilitates the manufacturing process.

[0026] Furthermore, a protrusion is arranged along the boundary of the effective resonance region, so that the acoustic impedance inside the effective resonance region and the region where the protrusion is located are mismatched, which effectively prevents the lateral leakage of the sound wave and improves the quality factor of the resonator;

[0027] Furthermore, an effective resonance area of ​​the resonator is defined by the first groove and the second groove, and the first groove and the second groove respectively penetrate the first electrode and the second electrode. The piezoelectric layer maintains a complete film layer without being etched, thereby ensuring the structural strength of the resonator and improving the yield rate of manufacturing the resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] Figure 1 A schematic structural diagram of a thin film bulk acoustic wave resonator according to Example 1 is shown.

[0030] Figures 2 to 11 A structural schematic diagram corresponding to different steps of a method for manufacturing a thin film bulk acoustic wave resonator in Example 2 is shown.

[0031] Description of reference numerals:

[0032] 100A-first semiconductor layer; 100B-first device layer; 1000-first microdevice; 1001-first conductive plug; 101-bonding layer; 102 dielectric layer; 103-first electrode; 104-piezoelectric layer; 105-second electrode; 106-bonding layer; 110a-first cavity; 110b-second cavity; 120-conductive interconnect structure; 130a-first groove; 130b-second groove; 141-first conductive interconnect layer; 142-first conductive protrusion; 151-second conductive interconnect layer; 152-second conductive protrusion; 160-insulating layer; 200A-second semiconductor layer; 200B-second device layer; 2000-second microdevice; 2001-second conductive plug; 40-protrusion; 300-temporary substrate. DETAILED DESCRIPTION

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] Example 1

[0039] 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:

[0040] A carrier substrate, the carrier substrate comprising a first semiconductor layer 100A and a first device layer 100B;

[0041] A first micro device 1000, wherein the first micro device 1000 is embedded in the carrier substrate, and at least a portion of the first micro device 1000 is located in the first device layer 100B;

[0042] A dielectric layer 102 is bonded to the first device layer 100B, the dielectric layer 102 encloses a first cavity 110a, and the first cavity 110a exposes the surface of the carrier substrate;

[0043] A piezoelectric stack structure covering the first cavity 110a, wherein the piezoelectric stack structure comprises a first electrode 103, a piezoelectric layer 104, and a second electrode 105 stacked in sequence from bottom to top, and the first cavity 110a is formed before the piezoelectric stack structure and is located below the piezoelectric stack structure;

[0044] The first electrical connection structure is connected to the first micro device, and the first electrical connection structure is used to supply power to the first micro device.

[0045] It should be noted that the first cavity 110a is formed before the piezoelectric stack structure and is located below the piezoelectric stack structure. The following explanation is given: In the prior art, the manufacturing process of the resonator is to etch a cavity on the substrate, fill the cavity with a sacrificial layer material, form a piezoelectric stack structure above the sacrificial layer material and the substrate, and after releasing the sacrificial layer, form a lower cavity, and the piezoelectric stack structure is suspended above the lower cavity. After the piezoelectric stack structure is formed, a capping layer can also be formed on the upper surface of the piezoelectric stack, and the cavity between the capping layer and the piezoelectric stack structure is the 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 needs to provide better support for the patterning process of the second electrode of the resonator, the production and patterning of the bonding layer, the production / grinding of the capping layer, or the production of the second electrical connection structure. Since the present structure bonds the carrier substrate to the dielectric layer by bonding, it is possible to pre-form the first micro-device in the carrier substrate. The lower cavity is formed by the sacrificial layer method, and the micro device cannot be formed at the bottom of the lower cavity. Before bonding the carrier substrate, the first micro device is pre-formed in the carrier substrate to shorten the process time. The micro device can be made separately without being made in the resonator manufacturing process, avoiding the resonator structure from being subjected to the process environment when making the micro device, and improving the stability of the resonator.

[0046] 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 where the first cavity 110a is located, 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 can be completely located in the device layer 100B. When the first micro device 1000 is a triode or a MOS transistor, its source and drain can be located in the first semiconductor layer 100A.

[0047] The material of the first semiconductor layer 100A includes 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. 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 combined by bonding. The material of the dielectric layer 102 can 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 bond bonding can be used for direct bonding. When the materials of the first device layer 100B and the dielectric layer 102 are different, a bonding layer can be formed on the bonding surface of the two, and the material of the bonding layer includes: silicon oxide, silicon nitride, polysilicon, ethyl silicate or 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 atomic bonds, so 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. It can be seen from the materials of the dielectric layer and the bonding layer that the materials of the two can be the same or different.

[0048] In this embodiment, the first cavity 110a is a closed cavity, and the first cavity 110a can 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 can also be circular, elliptical, or a polygon other than a rectangle, such as a pentagon, a hexagon, etc.

[0049] A piezoelectric stack structure is provided above the first cavity 110a, and the piezoelectric stack structure includes a first electrode 103, a piezoelectric layer 104, and a second electrode 105 from bottom to top. The first electrode 103 is located on the dielectric layer 102, the piezoelectric layer 104 is located on the first electrode 103, and the 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 have 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 the area surrounded by the first cavity 110a. The shape of the effective resonance area is an irregular polygon, such as a pentagon or hexagon without parallel opposite sides.

[0050] In this embodiment, the piezoelectric layer 104 covers the first cavity 110a. Covering the first cavity 110a should be understood as the piezoelectric layer 104 being a complete film layer without being etched. It does not mean that the piezoelectric layer 104 completely covers the first cavity 110a to form a sealed cavity. Of course, the piezoelectric layer 104 can completely cover the first cavity 110a to form a sealed cavity. The piezoelectric layer is not etched to ensure that the piezoelectric laminate structure has a certain thickness, so that the resonator has a certain structural strength. Improve the yield rate of resonator manufacturing.

[0051] In one embodiment, an etch stop layer is further provided between the dielectric layer 102 and the first electrode 103, and its material includes but is not limited to silicon nitride (Si3N4) and silicon oxynitride (SiON). The etch stop layer can be used to increase the structural stability of the thin film bulk acoustic wave resonator finally manufactured on the one hand, and on the other hand, the etch stop layer has a lower etching rate than the dielectric layer 102, and can prevent over-etching in the process of etching the dielectric layer 102 to form the first cavity 110a, and protect the surface of the first electrode 103 thereunder from being damaged, thereby improving the device performance and reliability.

[0052] In this embodiment, a bonding layer 106 is included above the structure of the piezoelectric stack, and the bonding layer 106 encloses a second cavity 110b. The second cavity 110b exposes the surface of the piezoelectric stack structure, and the second cavity 110b is located above the first cavity 110a. A cover substrate is also included, which is disposed on the bonding layer 106 and covers the second cavity 110b. In this embodiment, a second micro-device 2000 is embedded in the cover substrate near the second cavity 110b.

[0053] In this embodiment, the cover substrate is a double-layer structure, including a second semiconductor layer 200A and a second device layer 200B. The second device layer 100B is close to the side where the second cavity 110b is located, and the first microdevice 1000 is at least partially formed in the second device layer 200B. The type of the second microdevice 1000 and its positional relationship with the cover substrate refer to the relevant description of the type of the first microdevice 1000 and its positional relationship with the carrier substrate, the optional materials of the second semiconductor layer 200A refer to the material types of the first semiconductor layer 100A, and the optional materials of the second device layer 200B refer to the material types of the first device layer 100B, which will not be repeated here. The bonding layer 106 can be made of conventional bonding materials, such as silicon oxide, silicon nitride, silicon oxynitride, ethyl silicate, etc., or it can be an adhesive such as a photocurable material or a thermosetting material, such as a die attach film (DAF) or a dry film (Dry Film), and the manufacturing and patterning process is relatively simple. The material of the bonding layer and the material of the cover substrate 200 may be the same, and the two are an integrated structure. The second cavity 110 b is formed by forming a space in the film layer (forming the bonding layer 106 and the cover substrate 200 ).

[0054] 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 .

[0055] In this embodiment, the first conductive plug 1001 extends from the bottom surface of the carrier substrate to the first micro device 1000 , and the second conductive plug 2001 extends from the bottom surface of the carrier substrate to the second micro device 2000 .

[0056] In another embodiment, the first conductive plug may extend from the top surface of the cover substrate to the first micro-device. The second conductive plug also extends from the top surface of the cover substrate to the second micro-device. In the above two cases, both conductive plugs are electrically connected to the micro-device from the same side of the resonator. The main consideration is that when making the conductive plug, the opposite side of the conductive plug needs to have a certain strength of support. When making the conductive plug, one side of the conductive plug (the supporting substrate or the cover substrate) needs to be thinned to a thickness of about 100 microns, and the opposite side of the conductive plug (the supporting substrate or the cover substrate) is not thinned to a thickness of about several hundred microns, providing a certain strength of support for the manufacturing process. Of course, if the process conditions permit, the first conductive plug and the second conductive plug can be arranged on opposite sides of the resonator. In one embodiment, a third electrical connection structure, such as a third conductive plug, can also be included to electrically connect the first micro-device and the second micro-device.

[0057] In this embodiment, it also includes a first electrode lead-out portion and a second electrode lead-out portion. The first electrode lead-out portion is used to introduce an electrical signal into the first electrode 103 of the effective resonance area, and the second electrode lead-out portion is used to introduce an electrical signal into the second electrode 105 of the effective resonance area. After the first electrode 103 and the second electrode 105 are energized, a pressure difference is generated on the upper and lower surfaces of the piezoelectric layer 104, forming a standing wave oscillation. The conductive interconnection structure 120 is used to short-circuit the first electrode and the second electrode outside the effective resonance area. As can be seen from the figure, the area outside the effective resonance area also includes an area 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 energized, a pressure difference can also be generated on the upper and lower surfaces of the piezoelectric layer outside the effective resonance area, and standing wave oscillations are also generated. However, standing wave oscillations outside the effective resonance area are undesirable. In this embodiment, the first electrode and the second electrode outside the effective resonance area are short-circuited, so that the upper and lower voltages of the piezoelectric layer outside the effective resonance area are consistent, and standing wave oscillations cannot be generated outside the effective resonance area, thereby improving the Q value of the resonator. 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:

[0058] The first electrode lead-out portion comprises:

[0059] A first through hole 140, wherein the first through hole 140 penetrates the lower structure of the first electrode 103 outside the effective resonance region to expose the first electrode 103; a first conductive interconnection layer 141, covering the inner surface of the first through hole 140 and a portion of the surface of the carrier substrate 100 around the first through hole 140, and connected to the first electrode 103; an insulating layer 160, covering the first conductive interconnection layer 141 and the surface of the carrier substrate 100; and a conductive protrusion 142, disposed on the surface of the carrier substrate 100 and connected to the first conductive interconnection layer 141.

[0060] The second electrode lead-out portion comprises:

[0061] A second through hole 150, wherein the second through hole 150 penetrates 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 the inner surface of the second through hole 150 and a portion of the surface of the carrier substrate 100 around the second through hole 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 protrusion 152, disposed on the surface of the carrier substrate 100 and connected to the second conductive interconnection layer 151.

[0062] In this embodiment, a protrusion 40 is provided at the boundary of the effective resonance region, and the protrusion 40 is provided on the upper surface or the lower surface of the piezoelectric stack structure; or, the protrusion 40 is partially provided on the upper surface of the piezoelectric stack structure and partially provided on the lower surface of the piezoelectric stack structure.

[0063] In this embodiment, the protrusions 40 are all located on the lower surface of the piezoelectric stack structure. They are all located on the side where the first cavity 110a is located. The area surrounded by the protrusions 40 is the effective resonance area, and the outside of the protrusions 40 is the invalid resonance area. The first electrode 103, the piezoelectric layer 104, and the second electrode 105 in the effective resonance area overlap each other in a direction perpendicular to the carrier substrate 100. In other embodiments, the protrusions 40 can be all located on the upper surface of the piezoelectric stack structure, away from the side where the first cavity 110a is located. The protrusions 40 can also be partially arranged on the upper surface of the piezoelectric stack structure and partially arranged on the lower surface of the piezoelectric stack structure.

[0064] In this embodiment, the projection of the protrusion 40 on the carrier substrate 100 forms a closed ring, such as a closed irregular polygon, circle or ellipse. The protrusion 40 makes the acoustic impedance of the effective resonance area inside it and the area where the protrusion 40 is located mismatched, which can effectively prevent the lateral leakage of sound waves and improve the quality factor of the resonator. In other embodiments, the projection of the protrusion 40 on 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 conducive to preventing the lateral leakage of sound waves.

[0065] The material of the protrusion 40 can be a conductive material or a dielectric material. When the material of the protrusion 40 is a conductive material, it can be the same as the material of the first electrode 103 or the second electrode 105. When the material of the protrusion 40 is a dielectric material, it can be any one of silicon oxide, silicon nitride, silicon oxynitride or silicon carbonitride, but is not limited to the above materials.

[0066] In this embodiment, the surface of the piezoelectric stack structure 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 structure, on the side where the first cavity 110a is located, penetrates 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 the second electrode 105, and surrounds the periphery of the area where the protrusion 40 is located. The two ends of the first groove 130a are arranged opposite to the two ends of the second groove 130b, so that the first groove 130a and the second groove 130b are connected or provided with a gap at two intersections of the projection of the carrier substrate 100. 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 arranged along the outer boundary of the protrusion 40, that is, the outer boundary of the protrusion 40 coincides with the inner edges of the first groove 130a and the second groove 130b. The projections of the first groove 130 a and the second groove 130 b on the carrier substrate 100 are closed shapes, which are consistent with the shapes of the projections of the protrusions 40 on the carrier substrate 100 and are located at the periphery of the projections formed by the protrusions 40 .

[0067] It should be understood that the protrusion 40 is annular (when the protrusion 40 is entirely located on the lower surface or the upper surface of the piezoelectric stack structure, the protrusion 40 forms an annular shape; when the protrusion 40 is located on both surfaces of the piezoelectric stack structure, the projections of the two parts of the protrusion together form an integral annular shape). When the protrusion 40 is entirely located on the upper surface or the lower surface of the piezoelectric stack structure, the first groove 130a surrounds the outer circumference of part of the protrusion 40, and the second groove 130b surrounds the outer circumference of the remaining part of the protrusion 40 (in this case, the second groove 130b surrounds the outer circumference of the protrusion 40, which means that it surrounds the outer circumference of the surface of the piezoelectric stack structure in the area of ​​the protrusion 40, and does not directly surround the outer circumference of the protrusion 40). When 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, the first groove 130a may surround the outer periphery of the protrusion 40 located on the lower surface of the piezoelectric stack structure, and the second groove 130b may surround the outer periphery of the protrusion 40 located on the upper surface of the piezoelectric stack structure. However, the present invention is not limited thereto, as long as the first groove 130a and the second groove 130b cooperate with each other to surround the outer periphery of the area where the protrusion 40 is located.

[0068] The protrusion 40 causes the acoustic impedance of the inner area of ​​the protrusion to be mismatched with the acoustic impedance of the area where the protrusion is located, defining the boundary of the effective resonance area of ​​the resonator. The first groove 130a and the second groove 130b respectively separate the first electrode 103 and the second electrode 105, so that the resonator cannot meet the working conditions (the working conditions are that the first electrode 103, the piezoelectric layer 104 and the second electrode 105 overlap each other in the thickness direction), further defining the boundary of the effective resonance area of ​​the resonator. The protrusion 40 causes the acoustic impedance to be mismatched by adding a mass block, and the first groove 130a and the second groove 130b cause the acoustic impedance to be mismatched by making the electrode end surface contact with the air. Both of them play a role in preventing the problem of shear wave leakage and improving the Q value of the resonator. Of course, in other embodiments, only the first groove 130a or the second groove 130b may be provided separately. Since the first electrode 103 and the second electrode 105 need to introduce electrical signals, the first groove 130a or the second groove 130b is not suitable for forming a closed ring. In this case, the first groove 130a or the second groove 130b cannot completely surround the area where the protrusion 40 is located. The first groove 130a or the second groove 130b can be formed into a nearly closed ring, and the non-enclosed area is used to introduce electrical signals. This arrangement can simplify the process flow and reduce the cost of the resonator.

[0069] In this embodiment, a conductive interconnection structure 120 is further included. The conductive interconnection structure 120 includes two parts. One part is arranged in the outer area of ​​the second groove 130b, connecting the first electrode 103 and the second electrode 105, and electrically connected to the first electrode lead-out portion through the first electrode 103. The other part of the conductive interconnection structure 120 is arranged in the outer area of ​​the first groove 130a, connecting the first electrode 103 and the second electrode 105, and electrically connected to the second electrode lead-out portion through the first electrode 103. Both parts of the conductive interconnection structure 120 are provided with an area covering a part of the surface of the second electrode 105, which increases the contact area with the second electrode 105, reduces the contact impedance, and can prevent local high temperature caused by excessive current.

[0070] It should be noted that 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 in the effective resonance region through the conductive interconnect structure 120. It can be seen that the first electrode lead-out portion and the second electrode lead-out portion are consistent in structure, but are arranged in 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. 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 interconnect structure 120, and is not connected to the second electrode inside the effective resonance region. Similarly, the second electrode lead-out portion is connected to the first electrode outside the effective resonance region and the second electrode inside the effective resonance region to supply power to the second electrode inside the effective resonance region.

[0071] Example 2

[0072] Embodiment 2 provides a method for manufacturing a thin film bulk acoustic wave resonator, comprising the following steps:

[0073] S01: providing a temporary substrate;

[0074] S02: forming a piezoelectric stack structure on the temporary substrate, wherein the piezoelectric stack structure includes a second electrode, a piezoelectric layer, and a first electrode arranged in sequence from bottom to top;

[0075] S03: forming a dielectric layer to cover the piezoelectric stack structure;

[0076] S04: patterning the dielectric layer to form a first cavity, wherein the first cavity penetrates the dielectric layer;

[0077] S05: 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 a first surface of the carrier substrate, and a side where the first device layer is located is a side where the first surface of the carrier substrate is located;

[0078] S06: bonding the carrier substrate to the dielectric layer to cover the first cavity, and making the first surface face the first cavity;

[0079] S07: removing the temporary substrate;

[0080] S08: forming a first electrical connection structure to electrically connect the first micro-device to an external signal.

[0081] It should be noted that S0N is not used to limit the sequence of steps. Figures 2 to 11 FIG. 1 is a schematic diagram showing the structure of different stages of a method for manufacturing a thin film piezoelectric acoustic wave resonator according to Embodiment 2 of the present invention. Figures 2 to 11 , explaining each step in detail.

[0082] refer to Figure 2 , executing step S01: providing a temporary substrate 300 .

[0083] The temporary 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, or a ceramic substrate such as aluminum oxide, a quartz or glass substrate, etc.

[0084] refer to Figure 3, executing step S02: forming a piezoelectric stack structure on the temporary substrate 300, wherein the piezoelectric stack structure includes a second electrode 105, a piezoelectric layer 104, and a first electrode 103 arranged in sequence from bottom to top.

[0085] The materials of the second electrode 105 and the first electrode 103 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 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 105 and the first electrode 103 can be formed by physical vapor deposition or chemical vapor deposition methods such as magnetron sputtering and evaporation. The material of the piezoelectric layer 104 can be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz (Quartz), potassium niobate (KNbO3) or lithium tantalate (LiTaO3) and a combination thereof. When the piezoelectric layer 104 includes aluminum nitride (AlN), the piezoelectric layer 104 may also include a rare earth metal, such as scandium (Sc), erbium (Er), yttrium (Y) and lanthanum (La). In addition, when the piezoelectric layer 104 includes aluminum nitride (AlN), the piezoelectric layer 104 may also include a transition metal, such as zirconium (Zr), titanium (Ti), manganese (Mn) and hafnium (Hf). The piezoelectric layer 104 can be deposited and formed by any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition or atomic layer deposition. Optionally, in this embodiment, the second electrode 105 and the first electrode 103 are made of metal molybdenum (Mo), and the piezoelectric layer 104 is made of aluminum nitride (AlN).

[0086] refer to Figure 4 , executing step S03: forming a dielectric layer 102 to cover the piezoelectric stacked structure.

[0087] The dielectric layer 102 is formed by physical vapor deposition or chemical vapor deposition. The material of the dielectric layer 102 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.

[0088] refer to Figure 5 , executing step S05: patterning the dielectric layer 102 to form a first cavity 110 a , wherein the first cavity 110 a penetrates the dielectric layer 102 .

[0089] 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 can be a wet etching process or a dry etching process, and dry etching includes but is not limited to reactive ion etching (RIE), ion beam etching, and plasma etching. The depth and shape of the first cavity 110a depend on the depth and shape of the cavity required for the bulk acoustic wave resonator to be manufactured, that is, the depth of the first cavity 110a can be determined by forming the thickness of the dielectric layer 102. The shape of the bottom surface of the first cavity 110a can be a rectangle or a polygon other than a rectangle, such as a pentagon, a hexagon, an octagon, etc., or it can be a circle or an ellipse.

[0090] refer to Figure 6 , perform step S05: provide a carrier substrate, the carrier substrate includes a first semiconductor layer 100A and a first device layer 100B, a first surface of the carrier substrate is embedded with a first micro device 1000, and the side where the first device layer 100B is located is the side where the first surface of the carrier substrate is located. 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 relevant description of Example 1, and will not be repeated here.

[0091] refer to Figure 7 , perform step S06: bond the carrier substrate to the dielectric layer 102 to cover the first cavity 110a, and make the first surface face the first cavity 110a. The material of the dielectric layer and the bonding method between the dielectric layer and the carrier substrate refer to the relevant description of embodiment 1.

[0092] refer to Figure 8 , executing step S07: removing the temporary substrate. The temporary substrate can be removed by mechanical grinding.

[0093] refer to Fig. 9 and Fig.10In this embodiment, before forming the first electrical connection structure and connecting the first micro-device, it also includes: forming a bonding layer 106 on the piezoelectric stack structure, the bonding layer 106 enclosing a second cavity 110b, the second cavity 110b exposing the surface of the piezoelectric stack structure, and the second cavity 110b is located above the first cavity 110a. Provide a cover substrate, the cover substrate includes a second semiconductor layer 200A and a second device layer 200B, the first surface of the cover substrate is embedded with a second micro-device 2000, and the side where the second device layer 200B is located is the side where the first surface of the cover substrate is located. The cover substrate is arranged on the bonding layer 106, covering the second cavity 110b, and the first surface of the cover substrate is facing the second cavity 110b. 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 cover substrate refer to the relevant description of Example 1, and will not be repeated here.

[0094] refer to Fig.11 , executing step S08: forming a first electrical connection structure to electrically connect the first micro-device to an external signal. This embodiment also includes: forming a second electrical connection structure to electrically connect the second micro-device to an external signal. The first electrical connection structure and the second electrical connection structure are respectively a first conductive plug 1001 and a second conductive plug 2001. In this embodiment, forming the first conductive plug 1001 and the second conductive plug 2001 includes: forming a first through hole (not shown in the figure) penetrating the carrier substrate from the carrier substrate side and a second through hole (not shown in the figure) penetrating the carrier substrate and the upper structure of the carrier substrate (in this embodiment, the upper structure includes a dielectric layer 102, a piezoelectric stack structure, a bonding layer 106 and a part of the second device layer 200B), the first through hole exposing the first micro-device 1000, the second through hole exposing the second micro-device 2000, and forming a conductive material 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 through hole and the second through hole may be formed by a dry etching process, and the conductive material may be formed in the first through hole and the second through hole by an electroplating or chemical plating process.

[0095] In another embodiment, forming the first conductive plug 1001 and the second conductive plug 2001 includes: forming a third through hole penetrating the cover substrate from the cover substrate side and a fourth through hole penetrating the cover substrate and the structure below the cover substrate, the third through hole exposing the second microdevice, the fourth through hole exposing the first microdevice, and forming a conductive material in the third through hole and the fourth through hole to form the second conductive plug and the first conductive plug.

[0096] The above two conductive plugs are formed on the same side of the resonator (the side where the carrier substrate is located or the side where the cover substrate is located). The reason for this arrangement is described in detail in Example 1. Before the conductive plug is formed on the side where the carrier substrate is located, the carrier substrate is thinned by supporting the cover substrate; before the conductive plug is formed on the side where the cover substrate is located, the cover substrate is thinned by supporting the carrier substrate.

[0097] In this embodiment, a first electrode lead-out portion and a second electrode lead-out portion are formed, wherein the first electrode lead-out portion is connected to the first electrode 103, and 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 where the carrier substrate is located. 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 also located on the side where the cover substrate is located.

[0098] The forming of the first electrode lead-out portion comprises:

[0099] A through hole penetrating the lower structure of the first electrode 103 is formed by an etching process, the through hole exposes the first electrode 103, and a first conductive interconnection layer 141 is formed in the through hole by an electroplating process or a physical vapor deposition process, the first conductive interconnection layer 141 covers the inner surface of the through hole and a portion of the surface of the carrier substrate 100 at the periphery of the through hole, and is connected to the first electrode 103; an insulating layer 160 is formed on the surface of the first conductive interconnection layer 141 by a deposition process; a first conductive protrusion 142 is formed on the surface of the carrier substrate, and the first conductive protrusion 142 is electrically connected to the first conductive interconnection layer 141.

[0100] Forming the second electrode lead-out portion includes:

[0101] A through hole penetrating the lower structure of the first electrode 103 is formed by an etching process, the through hole exposes the second electrode 105, and a second conductive interconnection layer 151 is formed in the through hole by a deposition process or an electroplating process, the second conductive interconnection layer 151 covers the inner surface of the through hole and a portion of the surface of the carrier substrate at the periphery of the through hole, and is connected to the second electrode 105; an insulating layer 160 is formed on the surface of the second conductive interconnection layer 151 by a deposition process; a second conductive protrusion 152 is formed on the surface of the carrier substrate 100, and the second conductive protrusion 152 is electrically connected to the second conductive interconnection layer 151.

[0102] 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 structural embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0103] 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 carrier substrate, the carrier substrate comprising a first semiconductor layer and a first device layer; a first micro device, wherein the first micro device is embedded in the carrier substrate, and at least a portion of the first micro device is located in the first device layer; a dielectric layer bonded to the first device layer, the dielectric layer enclosing a first cavity, the first cavity exposing a surface of the carrier substrate; A piezoelectric stack structure covers the first cavity, wherein the piezoelectric stack structure includes a first electrode, a piezoelectric layer, and a second electrode stacked sequentially from bottom to top; a first electrical connection structure, connected to the first micro-device, electrically leading the first micro-device out; Also includes: A bonding layer is disposed above the piezoelectric stack structure, the bonding layer encloses a second cavity, the second cavity exposes the surface of the piezoelectric stack structure, and the second cavity and the projection of the first cavity on the piezoelectric stack structure have an overlapping portion; a cover substrate, disposed on the bonding layer and covering the second cavity; The capping substrate comprises a second semiconductor layer and a second device layer, wherein the second device layer is close to a side where the second cavity is located; and further comprises: a second micro device, wherein the second micro device is embedded in the cover substrate, and at least a portion of the second micro device is located in the second device layer; a second electrical connection structure connected to the second micro-device to electrically lead out the second micro-device; Also includes: A first groove is located inside the area surrounded by the first cavity and penetrates the first electrode, or penetrates the first electrode and the piezoelectric layer; a second groove, located inside the area surrounded by the second cavity, arranged opposite to the first groove in the lateral direction, and penetrating the second electrode, or penetrating the second electrode and the piezoelectric layer; The first groove and the second groove are connected or provided with a gap at two intersections of the projection of the carrier substrate.

2. The thin film bulk acoustic wave resonator according to claim 1, characterized in that The first electrical connection structure comprises: A first conductive plug extends from the bottom surface of the carrier substrate to the first micro device; or the first conductive plug extends from the top surface of the cover substrate to the first micro device.

3. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The second electrical connection structure comprises: A second conductive plug extends from the bottom surface of the carrier substrate to the first micro device; or the second conductive plug extends from the top surface of the cover substrate to the second micro device.

4. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: Also included is a third electrical connection structure, wherein the third electrical connection structure connects the first micro device and the second micro device.

5. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The first micro device and / or the second micro device comprises: Diodes, triodes, MOS transistors, electrostatic discharge protection devices, resistors, capacitors or inductors.

6. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The material of the first device layer includes silicon oxide, silicon nitride, silicon oxynitride or silicon carbonitride.

7. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The material of the dielectric layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate.

8. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The dielectric layer and the first device layer are made of the same material, and the bonding method includes: atomic bond bonding.

9. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: It also includes a bonding layer, which is arranged between the dielectric layer and the carrier substrate.

10. The thin film bulk acoustic wave resonator according to claim 9, characterized in that: The material of the bonding layer includes: silicon oxide, silicon nitride, polysilicon, ethyl silicate or organic curing film.

11. The thin film bulk acoustic wave resonator according to claim 10, characterized in that: The dielectric layer and the bonding layer are made of the same material.

12. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The area where the first electrode, the piezoelectric layer and the second electrode overlap each other in a direction perpendicular to the carrier substrate is an effective resonance area, the boundary of the effective resonance area is located in the area surrounded by the first cavity, a protrusion is arranged at the boundary of the effective resonance area, and the protrusion is arranged on the upper surface or the lower surface of the piezoelectric stack structure; or, The protrusion is partially disposed on the upper surface of the piezoelectric stack structure, and partially disposed on the lower surface of the piezoelectric stack structure.

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