A resonator and a method for preparing the same

Abstract

The present application provides a resonator and a preparation method thereof, relating to the technical field of resonators. The resonator includes a substrate and a bottom electrode, a piezoelectric layer, and a top electrode sequentially stacked on the substrate. The top electrode has an acoustic reflection portion located at the edge of a working area of ​​the resonator. The acoustic reflection portion arches toward at least one side away from the piezoelectric layer to form a plurality of reflection cavities between the piezoelectric layer and the top electrode. The acoustic impedance mismatch between the air inside the reflection cavity and the acoustic reflection portion is utilized to reflect transverse sound waves, thereby reducing longitudinal energy loss and improving the Q value of the resonator. In addition, because the acoustic reflection portion arches toward the side away from the piezoelectric layer, the top electrode can be effectively extended by the arching, thereby improving the thermal stability of the device through the top electrode and reducing the temperature drift coefficient of the resonator.

Description

Technical Field

[0001] The present application relates to the technical field of resonators, and in particular to a resonator and a method for preparing the same. Background Art

[0002] With the rapid development of wireless communications, an increasing number of devices are transmitting and receiving information at higher frequencies, placing increasingly stringent demands on RF front-end circuits and increasing demand for high-performance filters. Bulk acoustic wave filters, with their high quality factor, excellent out-of-band suppression, and high squareness coefficient, are becoming a mainstream market component.

[0003] BAW filters are constructed by cascading multiple resonators in a specific circuit. During operation, the piezoelectric effect generates transverse vibrations in thin film bulk acoustic wave resonators. This transverse vibration causes longitudinal acoustic waves to be transmitted to transverse acoustic waves, generating unnecessary parasitics, causing longitudinal energy loss, reducing the resonator's Q value, affecting the filter roll-off, increasing in-band ripple, and increasing insertion loss, which significantly affects device performance.

[0004] Therefore, it is necessary to provide a high-performance resonator with a higher Q value. However, in the prior art, the purpose is to improve the Q value of the resonator, while ignoring the heat dissipation of the resonator. Summary of the Invention

[0005] The purpose of this application is to address the deficiencies in the above-mentioned prior art and provide a resonator and a method for preparing the same, which can improve the Q value of the resonator while improving the heat dissipation capacity of the resonator so that the resonator has better stability.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of the present application are as follows:

[0007] In one aspect of an embodiment of the present application, a resonator is provided, comprising a substrate and a bottom electrode, a piezoelectric layer, and a top electrode stacked sequentially on the substrate, wherein the top electrode has an acoustic reflection portion located at an edge of a working area of ​​the resonator, and the acoustic reflection portion arches toward at least one side away from the piezoelectric layer to form a plurality of reflection cavities between the top electrode and the piezoelectric layer.

[0008] Optionally, an insulating isolation layer is provided between the sound reflecting portion and the piezoelectric layer.

[0009] Optionally, the sound reflecting portion includes a first sound reflecting portion, the first sound reflecting portion is an arch structure, and the insulating isolation layer is located between an edge end of the first sound reflecting portion away from the center of the working area and the piezoelectric layer.

[0010] Optionally, the sound reflecting part also includes a second sound reflecting part, which is an air wing. A passivation layer is also provided on the top electrode, and the edge end of the passivation layer extends from the suspended end of the air wing toward the piezoelectric layer, and the insulating isolation layer is located between the edge end of the passivation layer and the piezoelectric layer.

[0011] Optionally, the insulating isolation layer protrudes from the upper surface of the piezoelectric layer;

[0012] The top surface of the insulating isolation layer is flush with the upper surface of the piezoelectric layer;

[0013] Alternatively, the top surface of the insulating isolation layer is concave relative to the upper surface of the piezoelectric layer.

[0014] Optionally, a conductive layer is provided on the top electrode, and the conductive layer is an arched structure that arches away from the top electrode to form an air gap between the conductive layer and the top electrode, and an insulating isolation layer is provided between the edge end of the conductive layer away from the center of the working area and the top electrode.

[0015] Optionally, the sound reflecting portion further includes a third sound reflecting portion, and the third sound reflecting portion is an arch structure or an air wing;

[0016] And / or, there are multiple third sound reflecting parts, and the multiple third sound reflecting parts are arranged in sequence from the center to the edge of the working area.

[0017] Optionally, the bottom electrode has a raised portion raised toward a side facing away from the substrate, and an air cavity is formed between the substrate and the raised portion.

[0018] Optionally, a thickness M of the reflective cavity along the substrate thickness direction satisfies: 10 nm ≤ M ≤ 1000 nm;

[0019] From the center of the working area to the edge, the width L1 of the reflective cavity satisfies: 0.5um≤L1≤10um;

[0020] And / or; along the direction from the center of the working area toward the edge, the width L2 of the isolation layer satisfies: 0.5um≤L2≤5um.

[0021] Another aspect of the present invention provides a method for preparing a resonator, the method comprising:

[0022] Depositing a stacked bottom electrode and a piezoelectric layer in sequence on a substrate;

[0023] A top electrode is deposited on the piezoelectric layer, wherein the top electrode has an acoustic reflection portion located at an edge of a resonator working area, and the acoustic reflection portion arches toward at least one side away from the piezoelectric layer to form a plurality of reflection cavities between the top electrode and the piezoelectric layer.

[0024] Optionally, depositing a top electrode on the piezoelectric layer comprises:

[0025] depositing a sacrificial layer and an insulating isolation layer on the piezoelectric layer;

[0026] depositing an electrode layer on the piezoelectric layer, covering the sacrificial layer and the insulating isolation layer;

[0027] The patterned electrode layer forms a top electrode, wherein the sound reflecting portion includes a first sound reflecting portion covering the sacrificial layer to form an arched structure, and an edge end of the first sound reflecting portion away from the center of the working area is isolated from the piezoelectric layer by an insulating isolation layer;

[0028] The sacrificial layer is released to form a reflection cavity between the first sound reflecting portion and the piezoelectric layer.

[0029] According to another aspect of the embodiments of the present application, a filter is provided, comprising any one of the above-mentioned resonators.

[0030] The beneficial effects of this application include:

[0031] The present application provides a resonator and a preparation method thereof. The resonator includes a substrate and a bottom electrode, a piezoelectric layer and a top electrode stacked in sequence on the substrate. The top electrode has an acoustic reflection portion located at the edge of the resonator working area. The acoustic reflection portion arches toward at least one side away from the piezoelectric layer to form multiple reflection cavities between the piezoelectric layer. The acoustic impedance mismatch between the air inside the reflection cavity and the acoustic reflection portion is utilized to reflect transverse sound waves, thereby reducing the loss of longitudinal energy and improving the Q value of the resonator. In addition, since the acoustic reflection portion arches toward the side away from the piezoelectric layer, the top electrode can be effectively extended by the arching, thereby improving the thermal stability of the device through the top electrode and reducing the temperature drift coefficient of the resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 This is one of the state diagrams of a resonator preparation method provided in an embodiment of the present application;

[0034] Figure 2 The second state diagram of a resonator manufacturing method provided in an embodiment of the present application;

[0035] Figure 3 The third state diagram of a resonator manufacturing method provided in an embodiment of the present application;

[0036] Figure 4 A fourth state diagram of a resonator manufacturing method provided in an embodiment of the present application;

[0037] Figure 5 This is one of the structural diagrams of a resonator provided in an embodiment of the present application;

[0038] Figure 6 This is a second structural diagram of a resonator provided in an embodiment of the present application;

[0039] Figure 7 The third structural diagram of a resonator provided in an embodiment of the present application;

[0040] Figure 8 This is a fourth structural diagram of a resonator provided in an embodiment of the present application;

[0041] Figure 9 A fifth state diagram of a resonator manufacturing method provided in an embodiment of the present application;

[0042] Figure 10 A sixth state diagram of a resonator manufacturing method provided in an embodiment of the present application;

[0043] Figure 11 A fifth structural diagram of a resonator provided in an embodiment of the present application;

[0044] Figure 12 A sixth structural diagram of a resonator provided in an embodiment of the present application;

[0045] Figure 13 The seventh structural diagram of a resonator provided in an embodiment of the present application;

[0046] Figure 14 This is an eighth structural diagram of a resonator provided in an embodiment of the present application;

[0047] Figure 15 A schematic top view of a resonator provided in an embodiment of the present application;

[0048] Figure 16 This is a schematic diagram of the simulation of the resonator temperature drift coefficient of the transmission structure;

[0049] Figure 17 A schematic diagram of a resonator temperature drift coefficient simulation provided in an embodiment of the present application.

[0050] Icon: 110-substrate; 120-releasable layer; 121-air cavity; 130-bottom electrode; 131-arched portion; 140-piezoelectric layer; 141-electrode lead hole; 150-sacrificial layer; 151-reflection cavity; 160-lead metal; 170-gold protective layer; 180-top electrode; 191-third acoustic reflection portion; 192-first acoustic reflection portion; 193-second acoustic reflection portion; 194-conductive layer; 1941-air gap; 210-passivation layer; 220-insulating isolation layer. DETAILED DESCRIPTION

[0051] The embodiments set forth below represent the information necessary to enable those skilled in the art to practice the embodiments and illustrate the best mode for practicing the embodiments. After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and will recognize applications of these concepts not specifically set forth herein. It should be understood that these concepts and applications fall within the scope of the present disclosure and the appended claims.

[0052] It should be understood that although the terms first, second, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to regionally distinguish one element from another element. For example, without departing from the scope of this disclosure, a first element can be referred to as a second element, and similarly, a second element can be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0053] It should be understood that when an element (such as a layer, region or substrate) is referred to as being "on another element" or "extending onto another element", it may be directly on the other element or directly extending onto the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly on another element" or "extending directly onto another element", there are no intervening elements. Similarly, it should be understood that when an element (such as a layer, region or substrate) is referred to as being "above another element" or "extending over another element", it may be directly on the other element or directly extending over the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly on another element" or "extending directly over another element", there are no intervening elements. It should also be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0054] Relative terms, such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical", may be used herein to describe the relationship of one element, layer or region to another element, layer or region, as illustrated in the figures. It should be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0055] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms as well. It should also be understood that when used herein, the term "comprising" indicates the presence of the recited features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0056] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. It should also be understood that the terms used herein should be interpreted as having the same meaning as they have in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense unless otherwise explicitly defined herein.

[0057] Considering that the resonator may generate transverse acoustic waves during operation, Figures 5 to 8 as well as Figures 11 to 14 As shown, the present application provides the top electrode 180 of the resonator with an acoustic reflection portion, and the acoustic reflection portion is located at the edge of the working area of ​​the resonator. The acoustic reflection portion arches toward the side away from the piezoelectric layer 140, thereby forming a reflection cavity 151 between the acoustic reflection portion and the piezoelectric layer 140. The acoustic impedance mismatch between the air inside the reflection cavity 151 and the acoustic reflection portion is utilized to reflect the transverse sound waves, thereby reducing the loss of longitudinal energy and improving the Q value of the resonator. Moreover, since the acoustic reflection portion arches toward the side away from the piezoelectric layer 140, the top electrode 180 can be effectively extended by the arching, thereby improving the thermal stability of the device through the top electrode 180 and reducing the temperature drift coefficient of the resonator.

[0058] For ease of understanding, the resonator of the present application will be described below with reference to the accompanying drawings and through the preparation process.

[0059] In the first example:

[0060] S010: Provide a substrate 110. Figure 1 As shown, the substrate 110 may be a silicon substrate 110 , including but not limited to ordinary high-resistance, low-resistance, polycrystalline, and amorphous silicon wafers.

[0061] S011: forming a concave cavity structure on the substrate 110 by etching. The present application does not limit the shape of the cavity structure.

[0062] S012: Fill the cavity structure of the substrate 110 with a releasable layer 120. The releasable layer 120 may be flush with the upper surface of the substrate 110 around the cavity structure, such as Figure 1 As shown, the releasable layer 120 may also protrude from the upper surface of the substrate 110. Figures 6 to 8 as well as Figure 14 As shown, when the releasable layer 120 is flush with the upper surface of the substrate 110 around the cavity structure, the air cavity 121 after final release also does not protrude from the upper surface of the substrate 110; Figure 5 as well as Figures 11 to 13 As shown, when the releasable layer 120 protrudes from the upper surface of the substrate 110 , the air cavity 121 ultimately formed includes a portion protruding from the upper surface of the substrate 110 .

[0063] S013: Deposit metal on the substrate 110 and form a bottom electrode 130 covering the releasable layer 120 by patterning. The material of the bottom electrode 130 includes but is not limited to molybdenum, gold, aluminum, copper, titanium, tungsten, etc. Before depositing the metal for forming the bottom electrode 130, a seed layer can be pre-deposited to improve the film performance. Figure 1 As shown, when the releasable layer 120 protrudes from the upper surface of the substrate 110, the bottom electrode 130 can be arched in the direction away from the substrate 110, that is, the bottom electrode 130 has an arched portion 131. The arched portion 131 can appropriately expand the area where the metal region of the bottom electrode 130 contacts the air (due to the slope of the bottom electrode 130), thereby improving the thermal stability of the resonator.

[0064] S014: Depositing a piezoelectric layer 140 on the bottom electrode 130. Figure 2 As shown, the piezoelectric layer 140 can be made of a variety of piezoelectric materials, including AlN, PZT, ZnO, LiNbO 3 , LiTaO 3 , etc.

[0065] S015: An electrode extraction hole 141 exposing the bottom electrode 130 is formed on the piezoelectric layer 140 by etching. Figure 2 As shown, the electrode lead-out hole 141 exposes the bottom electrode 130 located below the piezoelectric layer 140, so that the bottom electrode 130 can be subsequently led out through the electrode lead-out hole 141. It is understood that the present application does not limit the order of S015, as long as it is located after S014 and before S017 or S021.

[0066] S016: Depositing a sacrificial layer 150 on the piezoelectric layer 140. After depositing the sacrificial material, the sacrificial layer 150 may be formed by patterning. Figure 3 As shown, the sacrificial layer 150 is used to form the reflection cavity 151 of the sound reflection part by releasing. Therefore, the position, shape and number of the sacrificial layer 150 can be reasonably set according to the position, shape and number of the required sound reflection part and the reflection cavity 151. For example, the sacrificial layer 150 can be located at the edge of the working area of ​​the resonator. It should be understood that, as Figure 3 As shown, the sacrificial layer 150 may include three parts, for example Figure 15 As shown, the sacrificial layer 150 may also include two parts, namely a ring-shaped part and a strip-shaped part. The present application does not impose any restrictions on the shape and number of the reflective cavities.

[0067] S017: Depositing metal on the piezoelectric layer 140 and forming a top electrode 180 covering the sacrificial layer 150 by patterning. Figure 4 As shown, the position where the top electrode 180 covers the sacrificial layer 150 will arch up to form an acoustic reflection portion. More specifically, the acoustic reflection portion is a third acoustic reflection portion 191. Of course, the metal deposited on the piezoelectric layer 140 can also be patterned to form a lead-out metal 160 located in the electrode lead-out hole 141.

[0068] S018: Depositing a gold protective layer 170. Figure 4 As shown, the gold protective layer 170 includes a portion filled in the electrode lead-out hole 141 ( Figure 4 The left part) and the part leading out the top electrode 180 ( Figure 4 middle right part).

[0069] S019: Release the releasable layer 120 and the sacrificial layer 150. Figure 5 As shown, by releasing the releasable layer 120, the original position of the releasable layer 120 becomes the air cavity 121, and by releasing the sacrificial layer 150, the original position of the sacrificial layer 150 becomes the reflective cavity 151. According to the different coverage of the top electrode 180 on the sacrificial layer 150, as shown in FIG. Figures 5 to 7 As shown, the third sound reflecting portion 191 may be an arched structure, for example Figure 8 As shown, the third sound reflecting portion 191 may be an air wing, that is, one end of the third sound reflecting portion 191 is suspended (suspended end).

[0070] In different embodiments of this example, the number of the third sound reflecting parts 191 can be different, for example, it can be one or more, and when it is multiple, it can include two, three, four, etc. The multiple third sound reflecting parts 191 can reflect the transverse sound waves multiple times, further improving the Q value. Figure 5 As shown in FIG, the number of the third sound reflecting portion 191 on the left side of the working area is one, the number of the third sound reflecting portion 191 on the right side of the working area is two, and the two third sound reflecting portions 191 on the right side are along the direction from the center of the working area to the edge (for example Figure 5 From left to right in the middle) are arranged in sequence; for example Figure 6 As shown, there is a third sound reflection portion 191 on the left and right sides of the working area; for example Figure 7As shown, there are two third sound reflection parts 191 on the left and right sides of the working area. The two third sound reflection parts 191 on the left are arranged along the direction from the center of the working area toward the edge, and the thickness of the reflection cavity 151 of the third sound reflection part 191 gradually increases and becomes a step form. The same is true for the two third sound reflection parts 191 on the right, thereby improving the effect of sound reflection.

[0071] For example Figure 8 As shown, when the third sound reflecting part 191 is an air wing, a passivation layer 210 can be deposited on the top electrode 180, and the passivation layer 210 can extend from the suspended end of the air wing toward the piezoelectric layer 140, so that the reflection cavity 151 of the air wing is closed, and the suspended end of the air wing is within the closed space.

[0072] In the second example:

[0073] This example is different from the previous example after S016. Specifically:

[0074] S020: Depositing an insulating isolation layer 220 on the piezoelectric layer 140. Figure 9 As shown, an insulating isolation layer 220 can be formed on the piezoelectric layer 140 by deposition. The isolation layer comprises a non-metallic material, such as SiN. Of course, the order of S020 and S016 is not limited. The number of the insulating isolation layer 220 can be one or more, and the shape can be any shape, such as Figures 9 to 14 As shown, there are two insulating isolation layers 220, each in a block shape, for example Figure 15 As shown, there is one insulating isolation layer 220 in a ring shape, and at least a portion of the insulating isolation layer 220 is located within the working area.

[0075] S021: depositing an electrode layer on the piezoelectric layer 140 to cover the sacrificial layer 150 and the insulating isolation layer 220. The electrode layer may be made of metal, such as molybdenum, gold, aluminum, copper, titanium, tungsten, etc.

[0076] S022: Patterning the electrode layer to form a top electrode 180, wherein Figure 10 As shown, the sound reflector includes a first sound reflector 192 covering the sacrificial layer 150 to form an arched structure, and the edge of the first sound reflector 192 away from the center of the working area is isolated from the piezoelectric layer 140 by the insulating isolation layer 220. Therefore, the insulating isolation layer 220 can prevent the landing point of the first sound reflector 192 from directly contacting the piezoelectric layer 140. In turn, the properties of the insulating isolation layer 220 are utilized to reduce the resulting parasitic effects and reduce the spurious modes of the resonator.

[0077] S023: Depositing a gold protective layer 170. Figure 10 As shown, the gold protective layer 170 includes a portion filled in the electrode lead-out hole 141 ( Figure 10 The left part) and the part leading out the top electrode 180 ( Figure 10 middle right part).

[0078] S024: Release the sacrificial layer 150 to form a reflection cavity 151 between the first sound reflecting portion 192 and the piezoelectric layer 140. Figure 11 As shown, by releasing the sacrificial layer 150, a reflection cavity 151 is formed between the first sound reflecting portion 192 and the piezoelectric layer 140, thereby utilizing the impedance mismatch between air and the first sound reflecting portion 192 to reflect the transverse sound wave, thereby improving the Q value. Figure 11 As shown, the releasable layer 120 may also be released, thereby forming an air cavity 121 .

[0079] In different implementations of this example, Figure 11 As shown, the insulating isolation layer 220 may protrude from the upper surface of the piezoelectric layer 140; Figure 12 As shown, the top surface of the insulating isolation layer 220 may also be flush with the upper surface of the piezoelectric layer 140 ; ​​the top surface of the insulating isolation layer 220 may also be recessed into the upper surface of the piezoelectric layer 140 (not shown in the figure).

[0080] In the third example:

[0081] The difference from the second example is that the sound reflecting portion further includes a second sound reflecting portion 193, and the second sound reflecting portion 193 is an air wing ( Figure 13 In the second acoustic reflection portion 193 on the left side of the middle portion, a passivation layer 210 is further provided on the top electrode 180, and the edge end of the passivation layer 210 extends from the suspended end of the air wing toward the piezoelectric layer 140, and the insulating isolation layer 220 is located between the edge end of the passivation layer 210 and the piezoelectric layer 140, that is, the passivation layer 210 can help to seal the reflection cavity 151 of the air wing.

[0082] In the fourth example:

[0083] The difference from the second example is that: Figure 14 As shown, a conductive layer 194 is provided on the top electrode 180. The conductive layer 194 is an arched structure that is arched away from the top electrode 180 to form an air gap 1941 between the conductive layer 194 and the top electrode 180. An insulating isolation layer 220 is provided between the edge end of the conductive layer 194 away from the center of the working area and the top electrode 180.

[0084] Furthermore, in different examples, e.g. Figure 14As shown, the thickness M of the reflective cavity along the thickness direction of substrate 110 satisfies the following conditions: 10 nm ≤ M ≤ 1000 nm. The width L1 of the reflective cavity along the direction from the center of the active area toward the edge satisfies the following conditions: 0.5 μm ≤ L1 ≤ 10 μm. The width L2 of the isolation layer along the direction from the center of the active area toward the edge satisfies the following conditions: 0.5 μm ≤ L2 ≤ 5 μm.

[0085] In addition, before depositing the bottom electrode 130, a seed layer can be deposited on the surface of the substrate 110 to facilitate the subsequent crystal growth of the metal electrode and the piezoelectric layer 140. The material of the seed layer is consistent with the material of the piezoelectric layer 140, and the thickness is usually between ten nanometers and several hundred nanometers.

[0086] An embodiment of the present application also provides a resonator, which includes a substrate 110 and a bottom electrode 130, a piezoelectric layer 140 and a top electrode 180 stacked in sequence on the substrate 110. In this way, when the resonator is working, longitudinal vibration is generated by the piezoelectric effect, thereby completing the conversion of electrical energy and mechanical energy.

[0087] Considering that the resonator may generate transverse acoustic waves during operation, Figures 5 to 8 as well as Figures 11 to 14 As shown, the top electrode 180 has an acoustic reflection portion, and is located at the edge of the working area of ​​the resonator. The acoustic reflection portion arches toward at least one side away from the piezoelectric layer 140, thereby forming a plurality of reflection cavities 151 between the acoustic reflection portion and the piezoelectric layer 140. The acoustic impedance mismatch between the air inside the reflection cavity 151 and the acoustic reflection portion is utilized to reflect the transverse sound waves, thereby reducing the loss of longitudinal energy and improving the Q value of the resonator. Moreover, since the acoustic reflection portion arches toward the side away from the piezoelectric layer 140, the top electrode 180 can be effectively extended by the arching, thereby improving the thermal stability of the device through the top electrode 180 and reducing the temperature drift coefficient of the resonator.

[0088] Alternatively, as Figures 5 to 8 as well as Figures 11 to 14 As shown, an air cavity 121 may be provided between the substrate 110 and the bottom electrode 130, thereby reflecting longitudinal acoustic waves through the air cavity 121 to improve the performance of the resonator. Of course, in other embodiments, a reflector may be provided between the substrate 110 and the bottom electrode 130.

[0089] It should be understood that the working area of ​​the resonator is the overlapping area of ​​the bottom electrode 130 , the piezoelectric layer 140 and the top electrode 180 along the thickness direction of the substrate 110 .

[0090] Optionally, an insulating isolation layer 220 is provided between the acoustic reflector and the piezoelectric layer 140. The isolation layer comprises a non-metallic material, such as SiN. The number of the insulating isolation layer 220 can be one or more, and the shape can be any shape, for example Figures 9 to 14 As shown, there are two insulating isolation layers 220, each in a block shape, for example Figure 15 As shown, there is one insulating isolation layer 220 in a ring shape. At least a portion of the insulating isolation layer 220 is located in the working area, and the insulating isolation layer 220 is used to prevent the parasitic capacitance with the bottom electrode 130 from affecting the performance.

[0091] Alternatively, as Figure 10 As shown, the sound reflecting portion includes a first sound reflecting portion 192 having an arched structure, and an insulating isolation layer 220 is located between the edge of the first sound reflecting portion 192 away from the center of the working area and the piezoelectric layer 140. Thus, the insulating isolation layer 220 prevents the landing point of the first sound reflecting portion 192 from directly contacting the piezoelectric layer 140. Furthermore, the properties of the insulating isolation layer 220 are utilized to reduce the resulting parasitic effects and thus reduce spurious modes of the resonator.

[0092] Alternatively, as Figure 13 As shown, the sound reflecting portion also includes a second sound reflecting portion 193, which is an air wing. A passivation layer 210 is also provided on the top electrode 180, and the edge end of the passivation layer 210 extends from the suspended end of the air wing toward the piezoelectric layer 140, and the insulating isolation layer 220 is located between the edge end of the passivation layer 210 and the piezoelectric layer 140, that is, the passivation layer 210 can help seal the reflection cavity 151 of the air wing.

[0093] Alternatively, as Figure 11 As shown, the insulating isolation layer 220 may protrude from the upper surface of the piezoelectric layer 140; Figure 12 As shown, the top surface of the insulating isolation layer 220 may also be flush with the upper surface of the piezoelectric layer 140 ; ​​the top surface of the insulating isolation layer 220 may also be recessed into the upper surface of the piezoelectric layer 140 (not shown in the figure).

[0094] Alternatively, as Figure 14 As shown, a conductive layer 194 is provided on the top electrode 180. The conductive layer 194 is an arched structure that is arched away from the top electrode 180 to form an air gap 1941 between the conductive layer 194 and the top electrode 180. An insulating isolation layer 220 is provided between the edge end of the conductive layer 194 away from the center of the working area and the top electrode 180.

[0095] Optionally, depending on the coverage of the top electrode 180 on the sacrificial layer 150, such as Figures 5 to 7 As shown, the third sound reflecting portion 191 may be an arched structure, for example Figure 8As shown, the third sound reflecting portion 191 may be an air wing, that is, one end of the third sound reflecting portion 191 is suspended (suspended end).

[0096] Optionally, the number of the third sound reflecting parts 191 can be different, for example, it can be one or more, and when it is multiple, it can include two, three, four, etc. The multiple third sound reflecting parts 191 can reflect the transverse sound waves multiple times, further improving the Q value. Figure 5 As shown in FIG, the number of the third sound reflecting portion 191 on the left side of the working area is one, the number of the third sound reflecting portion 191 on the right side of the working area is two, and the two third sound reflecting portions 191 on the right side are along the direction from the center of the working area to the edge (for example Figure 5 From left to right in the middle) are arranged in sequence; for example Figure 6 As shown, there is a third sound reflection portion 191 on the left and right sides of the working area; for example Figure 7 As shown, there are two third sound reflecting portions 191 on the left and right sides of the working area. The two third sound reflecting portions 191 on the left are arranged from the center of the working area toward the edge, and the thickness of the reflection cavity 151 of the third sound reflecting portions 191 gradually increases to form a step-like shape. The ends of the third sound reflecting portions 191 contact the upper surface of the piezoelectric layer 140. The two third sound reflecting portions 191 on the right can thus improve the sound reflection effect. In addition, the thickness of the third sound reflecting portions 191 on the left and right sides can be inconsistent in the vertical or horizontal direction.

[0097] Alternatively, as Figure 14 As shown, the thickness M of the reflective cavity along the thickness direction of substrate 110 satisfies the following conditions: 10 nm ≤ M ≤ 1000 nm. The width L1 of the reflective cavity along the direction from the center of the active area toward the edge satisfies the following conditions: 0.5 μm ≤ L1 ≤ 10 μm. The width L2 of the isolation layer along the direction from the center of the active area toward the edge satisfies the following conditions: 0.5 μm ≤ L2 ≤ 5 μm.

[0098] It should be noted that the simulation results of the temperature drift coefficient of the resonator with traditional structure are as follows Figure 16 As shown, the simulation results of the resonator temperature drift coefficient in this application are as follows Figure 17 As shown, it can be seen that the temperature drift coefficient of the resonator based on the traditional structure is -23.6ppm / ℃, and the temperature drift coefficient based on the present application is -17.7ppm / ℃. The temperature drift coefficient of the present application is improved by 25%. Therefore, the frequency temperature stability of the resonator is higher.

[0099] In another aspect of the embodiments of the present application, a filter is provided, comprising any one of the above-mentioned resonators, wherein the number of the resonators may be multiple, and the filter is formed by connecting the multiple resonators in series and / or in parallel.

[0100] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A resonator, characterized in that The resonator comprises a substrate, a bottom electrode, a piezoelectric layer, and a top electrode sequentially stacked on the substrate, wherein the top electrode has a sound reflecting portion located at an edge of the resonator working area, the sound reflecting portion arching toward at least one side away from the piezoelectric layer to form a plurality of reflection cavities between the piezoelectric layer and the sound reflecting portion; and at least one insulating isolation layer is provided between the sound reflecting portion and the piezoelectric layer. The reflective cavity is a closed area formed by at least part of the top electrode, the insulating isolation layer and the piezoelectric layer; The sound reflecting portion includes a first sound reflecting portion, the first sound reflecting portion is an arched structure, the insulating isolation layer is located between an edge end of the first sound reflecting portion away from the center of the working area and the piezoelectric layer, and the insulating isolation layer is located at a boundary of a reflection cavity of the first sound reflecting portion away from the working area, so that the insulating isolation layer can prevent a landing point of the first sound reflecting portion from directly contacting the piezoelectric layer; The sound reflection part also includes a third sound reflection part, and multiple third sound reflection parts are arranged in sequence from the center to the edge of the working area, and the thickness of the reflection cavity of the multiple third sound reflection parts gradually increases along the arrangement direction.

2. The resonator according to claim 1, wherein The sound reflecting portion also includes a second sound reflecting portion, which is an air wing. A passivation layer is also provided on the top electrode. The edge end of the passivation layer extends from the suspended end of the air wing toward the piezoelectric layer, and the insulating isolation layer is located between the edge end of the passivation layer and the piezoelectric layer.

3. The resonator according to claim 1 or 2, characterized in that The insulating isolation layer protrudes from the upper surface of the piezoelectric layer; The top surface of the insulating isolation layer is flush with the upper surface of the piezoelectric layer; Alternatively, the top surface of the insulating isolation layer is concave relative to the upper surface of the piezoelectric layer.

4. The resonator according to claim 1, wherein A conductive layer is provided on the top electrode, and the conductive layer is an arched structure that arches away from the top electrode to form an air gap between the conductive layer and the top electrode, and an insulating isolation layer is provided between the edge end of the conductive layer away from the center of the working area and the top electrode.

5. The resonator according to claim 1, wherein The third sound reflecting portion is an arch structure or an air wing.

6. The resonator according to any one of claims 1, 2, 4 and 5, characterized in that The bottom electrode has a raised portion raised toward a side away from the substrate, and an air cavity is formed between the substrate and the raised portion.

7. The resonator according to claim 1 or 2, characterized in that The thickness M of the reflective cavity along the thickness direction of the substrate satisfies: 10 nm ≤ M ≤ 1000 nm; Along the direction from the center of the working area to the edge, the width L1 of the reflective cavity satisfies: 0.5um≤L1≤10um; And / or; along the direction from the center of the working area toward the edge, the width L2 of the isolation layer satisfies: 0.5um≤L2≤5um.

8. A method for preparing a resonator, characterized in that: For preparing the resonator according to any one of claims 1 to 7, the method comprises: Depositing a stacked bottom electrode and a piezoelectric layer in sequence on a substrate; A top electrode is deposited on the piezoelectric layer, wherein the top electrode has a sound reflecting portion located at an edge of the resonator working area, and the sound reflecting portion is arched toward at least one side away from the piezoelectric layer to form a plurality of reflection cavities between the top electrode and the piezoelectric layer.

9. The method according to claim 8, wherein Depositing a top electrode on the piezoelectric layer comprises: depositing a sacrificial layer and an insulating isolation layer on the piezoelectric layer; Depositing an electrode layer on the piezoelectric layer, covering the sacrificial layer and the insulating isolation layer; Patterning the electrode layer to form a top electrode, wherein the sound reflecting portion includes a first sound reflecting portion covering the sacrificial layer to form an arched structure, and an edge end of the first sound reflecting portion away from the center of the working area is isolated from the piezoelectric layer by the insulating isolation layer; The sacrificial layer is released to form a plurality of reflection cavities between the first sound reflecting portion and the piezoelectric layer.

Images