Surface acoustic wave resonator and preparation method thereof, filter and electronic equipment

Abstract

The invention provides a surface acoustic wave resonator and a preparation method thereof, a filter and electronic equipment, and relates to the technical field of semiconductors. A metal layer is arranged on one side, deviating from a substrate, of a temperature compensation layer, namely, the metal layer is arranged above the temperature compensation layer, a dielectric layer is further arranged between the temperature compensation layer and the metal layer, and the orthographic projection of the metal layer in a first direction covers the tail end part of an interdigital electrode. The arrangement of the metal layer realizes a larger sound velocity difference by changing the sound velocity in the region, so that the transverse mode is reflected to different directions to avoid energy dissipation caused by resonance, and the purposes of suppressing miscellaneous mode interference, improving the Q value and improving the performance of the surface acoustic wave resonator are achieved. The dielectric layer can prevent the metal layer from being oxidized by the temperature compensation layer, so that the clutter suppression effect of the surface acoustic wave resonator can be improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a surface acoustic wave resonator and a preparation method thereof, a filter and an electronic device. Background Art

[0002] SAW (Surface Acoustic Wave) resonator is the abbreviation of surface acoustic wave resonator. It is a special filtering device made by using its piezoelectric effect and the physical characteristics of surface acoustic wave propagation. It is widely used in various fields, such as radio frequency. Among them, surface acoustic wave is an elastic wave with energy concentrated near the surface.

[0003] In the current SAW product design, the SAW resonator will have lateral resonance modes due to the acoustic waves propagating laterally in the SAW resonator, that is, noise appearing in and near the passband. This noise will increase the loss of the SAW resonator, cause the Q value to fluctuate greatly, and reduce the performance of the SAW resonator.

[0004] Therefore, how to suppress the interference of heterodyne modes, increase the Q value, and enhance the performance of surface acoustic wave resonators is the top priority in today's resonator design. Summary of the invention

[0005] In view of the above problems, the present application provides a surface acoustic wave resonator and a preparation method thereof, a filter and an electronic device, which can suppress heterogeneous mode interference, increase the Q value, and enhance the performance of the surface acoustic wave resonator. The specific scheme is as follows:

[0006] In a first aspect, the present application provides a surface acoustic wave resonator, the surface acoustic wave resonator comprising:

[0007] substrate;

[0008] An interdigital electrode located on one side of the substrate, the interdigital electrode comprising an interdigital electrode central portion and an interdigital electrode terminal portion;

[0009] a temperature compensation layer located on a side of the interdigital electrode facing away from the substrate;

[0010] a dielectric layer located on a side of the temperature compensation layer facing away from the substrate;

[0011] A metal layer is located on a side of the dielectric layer away from the substrate, and an orthographic projection of the metal layer in a first direction covers the end portion of the interdigitated electrode; the first direction is perpendicular to the plane where the substrate is located.

[0012] Preferably, in the above surface acoustic wave resonator, the metal layer is a metal layer that has been heat-treated in an oxygen-free atmosphere.

[0013] Preferably, in the above-mentioned surface acoustic wave resonator, the surface acoustic wave resonator further comprises:

[0014] A dielectric film layer is located on a side of the metal layer facing away from the substrate.

[0015] Preferably, in the above-mentioned surface acoustic wave resonator, the material of the dielectric film layer is silicon oxide material or silicon nitride material.

[0016] Preferably, in the above-mentioned surface acoustic wave resonator, the surface acoustic wave resonator further comprises:

[0017] A transparent conductive electrode layer is located on a side of the metal layer away from the substrate.

[0018] Preferably, in the above-mentioned surface acoustic wave resonator, the surface acoustic wave resonator further comprises:

[0019] A metal peroxide layer is located on a side of the metal layer facing away from the substrate.

[0020] Preferably, in the above-mentioned surface acoustic wave resonator, the surface acoustic wave resonator further comprises:

[0021] An anti-reflection layer is located on a side of the metal layer facing away from the substrate.

[0022] Preferably, in the above-mentioned surface acoustic wave resonator, the surface acoustic wave resonator further comprises: an interdigital electrode lead-out portion;

[0023] The interdigital electrode lead-out portion is electrically connected to the interdigital electrode;

[0024] The surface acoustic wave resonator further includes: a first through hole penetrating the dielectric layer and the temperature compensation layer;

[0025] The first through hole exposes a portion of the surface of the interdigital electrode lead-out portion;

[0026] The surface acoustic wave resonator further includes: a pad structure;

[0027] The pad structure is electrically connected to the interdigital electrode lead-out portion through the first through hole.

[0028] Preferably, in the above-mentioned surface acoustic wave resonator, the surface acoustic wave resonator further comprises: a passivation layer;

[0029] The passivation layer covers the pad structure, the metal layer and the exposed surface of the dielectric layer;

[0030] The passivation layer has a second through hole;

[0031] The second through hole exposes a portion of the surface of the pad structure.

[0032] Preferably, in the above-mentioned surface acoustic wave resonator, the material of the dielectric layer is SiN material, AlN material, amorphous silicon material or GaN material.

[0033] Preferably, in the above-mentioned surface acoustic wave resonator, the dielectric layer includes N layers of sub-dielectric layers stacked in sequence in the first direction;

[0034] Wherein, N≥2, and N is a positive integer.

[0035] A second aspect of the present application provides a method for preparing a surface acoustic wave resonator, the method for preparing the surface acoustic wave resonator comprising:

[0036] Providing a substrate:

[0037] forming an interdigital electrode on one side of the substrate, wherein the interdigital electrode comprises an interdigital electrode central portion and an interdigital electrode terminal portion;

[0038] forming a temperature compensation layer on a side of the interdigital electrode facing away from the substrate;

[0039] forming a dielectric layer on a side of the temperature compensation layer facing away from the substrate;

[0040] A metal layer is formed on a side of the dielectric layer facing away from the substrate, and the orthographic projection of the metal layer in a first direction covers the end portion of the interdigital electrode; the first direction is perpendicular to the plane where the substrate is located.

[0041] A third aspect of the present application provides a filter, comprising the surface acoustic wave resonator described in any one of the above items.

[0042] A fourth aspect of the present application provides an electronic device, the electronic device comprising the surface acoustic wave resonator described in any one of the above items;

[0043] Alternatively, the electronic device includes the filter described above.

[0044] By means of the above technical solution, the present application provides a surface acoustic wave resonator and a preparation method thereof, a filter and an electronic device, wherein a metal layer is arranged on the side of the temperature compensation layer away from the substrate, that is, a metal layer is arranged above the temperature compensation layer, and a dielectric layer is also arranged between the temperature compensation layer and the metal layer, and the orthographic projection of the metal layer in the first direction covers the end portion of the interdigital electrode. The arrangement of the metal layer achieves a greater sound velocity difference by changing the sound velocity in the region, so that the transverse mode is reflected in different directions to avoid the formation of resonance and energy dissipation, thereby achieving the purpose of suppressing heterodyne interference, improving the Q value, and enhancing the performance of the surface acoustic wave resonator. The dielectric layer can prevent the metal layer from being oxidized by the temperature compensation layer, thereby improving the heterodyne suppression effect of the surface acoustic wave resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0046] Figure 1 A partial structural schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present invention;

[0047] Figure 2 The embodiment of the present invention provides Figure 1 Schematic diagram of the cross section along the AA' direction;

[0048] Figure 3 The embodiment of the present invention provides Figure 1 Schematic diagram of the cross section along the BB' direction;

[0049] Figure 4 A schematic flow chart of a method for preparing a surface acoustic wave resonator provided in an embodiment of the present invention;

[0050] Figure 5-Figure 15 A partial structural schematic diagram of a surface acoustic wave resonator preparation process provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation method section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. It is known to those of ordinary skill in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems. It should be noted that the directional words appearing in the present invention are based on the relative position relationship shown in the drawings and cannot be used as an absolute limitation on the present application.

[0052] Combined with the content recorded in the background technology, the surface acoustic wave resonator and filter are an acoustic device widely used in the radio frequency field. They combine low insertion loss and good suppression performance, and are relatively small in size. They are used to filter out the interference of heterodyne signals, attenuate some frequency components, and only allow specified frequency components. They are the technical basis for the application of wireless spectrum as a non-renewable scarce resource. The specific principle can be simply understood as based on the piezoelectric properties of piezoelectric materials, using input and output transducer devices such as interdigital transducers to convert electrical signals into mechanical energy, and then convert them into electrical signals after processing, so as to amplify the required signals, filter out noise signals and improve signal quality. They are widely used in various wireless communication equipment.

[0053] At present, filters are mainly divided into SAW filters and BAW (Bulk Acoustic Wave) filters. Surface acoustic waves are an elastic wave that is generated and propagated on the surface of a piezoelectric substrate with piezoelectric properties, and whose amplitude decreases rapidly as the depth of the piezoelectric substrate increases. For SAW filters, their manufacturing cost is lower than that of BAW filters. They are mainly used in low-frequency bands, have low insertion loss and good suppression, and are highly temperature sensitive.

[0054] At the same time, it should be noted that SAW filters also have corresponding limitations, one of which is that they are easily affected by temperature changes. When the temperature rises, the stiffness of the base material tends to decrease and the speed of sound will also decrease. In other words, SAW filters have the defect of temperature drift, that is, the frequency will drift with the operating temperature. Therefore, based on the traditional SAW filter, a TC-SAW filter, that is, a temperature-compensated SAW filter, is produced accordingly. It mainly uses the temperature elastic properties of the temperature compensation layer (such as SiO2 layer) and the piezoelectric film layer that are opposite to each other to achieve compensation for the temperature drift characteristics.

[0055] Furthermore, SAW filters also have product designs such as TF-SAW filters (thin film surface acoustic wave filters), in which the design of the filter often uses a resonator as a basic unit, which can form a corresponding topology and amplify the specified frequency component signal.

[0056] For TC-SAW resonators, due to the acoustic waves propagating laterally in the surface acoustic wave resonator, the surface acoustic wave resonator will have a lateral resonance mode, that is, the noise appearing in and near the passband. This noise will increase the loss of the surface acoustic wave resonator, cause the Q value to fluctuate greatly, and reduce the performance of the surface acoustic wave resonator.

[0057] In the current prior art, a small metal block (commonly known as HammerHead in the field) is superimposed at the end of the interdigital electrode to form a convex shape to suppress clutter and ensure excellent filter performance. However, in the prior art, the metal block superimposed at the end of the interdigital electrode is in contact with the temperature compensation layer. During the use of the resonator, the metal block will be oxidized by the temperature compensation layer, thereby reducing the effect of suppressing clutter.

[0058] Based on this, the embodiment of the present invention provides a surface acoustic wave resonator and a preparation method thereof, a filter and an electronic device, by arranging a metal layer on the side of the temperature compensation layer away from the substrate, that is, arranging a metal layer above the temperature compensation layer, and a dielectric layer is also arranged between the temperature compensation layer and the metal layer, and the orthographic projection of the metal layer in the first direction covers the end portion of the interdigital electrode. The arrangement of the metal layer achieves a greater sound velocity difference by changing the sound velocity in the region, so that the transverse mode is reflected in different directions to avoid its resonance and energy dissipation, thereby achieving the purpose of suppressing the interference of the stray mode, improving the Q value, and improving the performance of the surface acoustic wave resonator. The dielectric layer can prevent the metal layer from being oxidized by the temperature compensation layer, thereby improving the stray wave suppression effect of the surface acoustic wave resonator.

[0059] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] refer to Figure 1 , Figure 1 A partial structural diagram of a surface acoustic wave resonator provided by an embodiment of the present invention; Figure 2 , Figure 2 The embodiment of the present invention provides Figure 1 Schematic diagram of the cross section in the AA' direction; reference Figure 3 , Figure 3 The embodiment of the present invention provides Figure 1 The surface acoustic wave resonator provided by the embodiment of the present invention comprises: a substrate 11.

[0061] The interdigital electrode 12 is located at one side of the substrate 11, and includes an interdigital electrode central portion A1 and an interdigital electrode terminal portion A2.

[0062] A temperature compensation layer 13 is located on a side of the interdigital electrode 12 facing away from the substrate 11 .

[0063] The dielectric layer 14 is located on a side of the temperature compensation layer 13 facing away from the substrate 11 .

[0064] The metal layer 15 is located on the side of the dielectric layer 14 away from the substrate 11 , and the orthographic projection of the metal layer 15 in a first direction covers the end portion A2 of the interdigitated electrode; the first direction is perpendicular to the plane where the substrate 11 is located.

[0065] Specifically, in the embodiment of the present invention, the interdigital electrode 12 includes a first interdigital electrode 121 and a second interdigital electrode 122, and the first interdigital electrode 121 and the second interdigital electrode 122 are placed crosswise and parallel. Both the first interdigital electrode 121 and the second interdigital electrode 122 include an interdigital electrode central portion A1 and an interdigital electrode terminal portion A2. In the embodiment of the present invention, the edge area of ​​the interdigital electrode 12 is defined as the interdigital electrode terminal portion A2, and the area within the interdigital electrode terminal portion A2 is defined as the interdigital electrode central portion A1.

[0066] like Figure 1-Figure 3 As shown, the surface acoustic wave resonator further includes: an interdigital electrode lead-out portion 16 .

[0067] The interdigital electrode lead-out portion 16 is electrically connected to the interdigital electrode 12 .

[0068] Among them, the interdigital electrode lead-out portion 16 includes a first interdigital electrode lead-out portion 161 and a second interdigital electrode lead-out portion 162. The first interdigital electrode lead-out portion 161 is electrically connected to the first interdigital electrode 121, and serves as an external electrical connection portion of the first interdigital electrode 121. The first interdigital electrode 121 and the first interdigital electrode lead-out portion 161 can be prepared in an integrated manner. The second interdigital electrode lead-out portion 162 is electrically connected to the second interdigital electrode 122, and serves as an external electrical connection portion of the second interdigital electrode 122. The second interdigital electrode 122 and the second interdigital electrode lead-out portion 162 can be prepared in an integrated manner.

[0069] like Figure 2 and Figure 3 As shown, the surface acoustic wave resonator further includes: a first through hole penetrating the dielectric layer 14 and the temperature compensation layer 13 .

[0070] The first through hole exposes a portion of the surface of the interdigital electrode lead-out portion 16 .

[0071] The surface acoustic wave resonator further includes a pad structure 17 .

[0072] The pad structure 17 is electrically connected to the interdigital electrode lead-out portion 16 through the first through hole.

[0073] In the embodiment of the present application, two first through holes are included, one of which exposes a portion of the surface of the first interdigital electrode lead-out portion 161, and the other first through hole exposes a portion of the surface of the second interdigital electrode lead-out portion 162. The pad structure 17 includes a first pad 171 and a second pad 172, wherein the first pad 171 is in contact and electrically connected with the first interdigital electrode lead-out portion 161 through the corresponding first through hole, and the second pad 172 is in contact and electrically connected with the second interdigital electrode lead-out portion 162 through the corresponding first through hole.

[0074] like Figure 2 and Figure 3 As shown, the surface acoustic wave resonator further includes a passivation layer 18 .

[0075] The passivation layer 18 covers the exposed surface of the pad structure 17 , the metal layer 15 and the dielectric layer 14 . The passivation layer 18 has a second through hole; the second through hole exposes a portion of the surface of the pad structure 17 .

[0076] The passivation layer 18 is provided to realize passivation protection of the surface acoustic wave resonator, thereby improving the performance and service life of the surface acoustic wave resonator. The second through hole is formed by processing the passivation layer 18, exposing a part of the surface of the pad structure 17, so as to realize the electrical connection of the surface acoustic wave resonator to the outside. In other words, the second through hole can be understood as a window for the surface acoustic wave resonator to be electrically connected to the outside.

[0077] It should be noted that the passivation layer 18 can also be used as a frequency adjustment layer of the surface acoustic wave resonator. The material of the passivation layer 18 includes but is not limited to insulating materials such as SiN, AlN, amorphous silicon, GaN, or a combination of two or more of them.

[0078] In summary, the surface acoustic wave resonator provided by the embodiment of the present invention is provided with a metal layer 15 on the side of the temperature compensation layer 13 away from the substrate 11, that is, the metal layer 15 is provided above the temperature compensation layer 13, and a dielectric layer 14 is also provided between the temperature compensation layer 13 and the metal layer 15, and the orthographic projection of the metal layer 15 in the first direction covers the end portion of the interdigital electrode 12. The provision of the metal layer 15 achieves a greater sound velocity difference by changing the sound velocity in the region, so that the transverse mode is reflected in different directions to avoid its resonance and energy dissipation, thereby achieving the purpose of suppressing the interference of the heterodyne mode, improving the Q value, and improving the performance of the surface acoustic wave resonator. The dielectric layer 14 can prevent the metal layer 15 from being oxidized by the temperature compensation layer 13, thereby improving the heterodyne suppression effect of the surface acoustic wave resonator.

[0079] In an optional embodiment of the present invention, the material of the dielectric layer 14 is SiN material, AlN material, amorphous silicon material, GaN material or other insulating materials.

[0080] In an optional embodiment of the present invention, the dielectric layer 14 includes a metal layer stacked in sequence in the first direction and heat-treated in an oxygen-free atmosphere, which can prevent the metal layer from being oxidized and improve the stability of the metal layer. In the embodiment of the present invention, the number of layers of the dielectric layer 14 is not limited, and it can be a single layer or a multi-layer stacked structure, as long as it can isolate the metal layer 15 from the temperature compensation layer 13.

[0081] It should be noted that, in the surface acoustic wave resonator, the dielectric layer 14 can also play the role of isolating the metal layer 15 from the temperature compensation layer 13 while realizing some required functions.

[0082] In an optional embodiment of the present invention, the metal layer is a metal layer that has been heat-treated in an oxygen-free atmosphere.

[0083] Specifically, in the embodiment of the present invention, by heat treating the metal layer in an oxygen-free atmosphere, the metal layer can be prevented from being oxidized, the stability of the metal layer can be improved, and the structural stability and working performance of the surface acoustic wave resonator can be improved.

[0084] In an optional embodiment of the present invention, the surface acoustic wave resonator further includes: a dielectric film layer located on a side of the metal layer facing away from the substrate.

[0085] Specifically, in the embodiment of the present invention, the material of the dielectric film layer includes but is not limited to silicon oxide material or silicon nitride material. By forming a dielectric film layer on the metal layer, the metal layer can be prevented from being oxidized, the stability of the metal layer can be improved, and the structural stability and working performance of the surface acoustic wave resonator can be improved.

[0086] In an optional embodiment of the present invention, the surface acoustic wave resonator further includes: a transparent conductive electrode layer located on a side of the metal layer facing away from the substrate.

[0087] Specifically, in the embodiment of the present invention, by forming a transparent conductive electrode layer on the metal layer, the metal layer can be prevented from being oxidized, the stability of the metal layer can be improved, and the structural stability and working performance of the surface acoustic wave resonator can be improved.

[0088] In an optional embodiment of the present invention, the surface acoustic wave resonator further includes: a metal peroxide layer located on a side of the metal layer facing away from the substrate.

[0089] Specifically, in the embodiment of the present invention, by forming a metal peroxide layer on the metal layer, the metal layer can be prevented from being oxidized, the stability of the metal layer can be improved, and the structural stability and working performance of the surface acoustic wave resonator can be improved.

[0090] In an optional embodiment of the present invention, the surface acoustic wave resonator further includes: an anti-reflection layer located on a side of the metal layer facing away from the substrate.

[0091] Specifically, in the embodiment of the present invention, the material of the anti-reflection layer includes but is not limited to silicon oxynitride material. By forming the anti-reflection layer on the metal layer, the apparent reflectivity of the metal layer can be reduced, thereby reducing the risk of the metal layer being oxidized by the temperature compensation layer 13, improving the stability of the metal layer, and further improving the structural stability and working performance of the surface acoustic wave resonator.

[0092] It should be noted that, based on the surface acoustic wave resonator provided by the technical solution of the present application, a wet gas oxidation method can be used after each film layer is prepared to form a highly uniform silicon oxide film on the surface of the film layer; a plasma oxidation method can also be used to form a high-quality silicon oxide film on the surface of the film layer. This can improve the structural stability of each film layer, and ultimately improve the structural stability and working performance of the surface acoustic wave resonator.

[0093] Based on the above embodiment of the present invention, another embodiment of the present invention further provides a method for preparing a surface acoustic wave resonator, referring to Figure 4 , Figure 4 A schematic flow chart of a method for preparing a surface acoustic wave resonator provided in an embodiment of the present invention. A method for preparing a surface acoustic wave resonator provided in an embodiment of the present invention comprises:

[0094] S101: Figure 5 As shown, a substrate 11 is provided.

[0095] Specifically, in this step, the material of the substrate 11 includes but is not limited to lithium niobate material, lithium tantalate material or other piezoelectric materials.

[0096] S102: Figure 6 , Figure 7 and Figure 8 As shown, an interdigital electrode 12 is formed on one side of the substrate 11 , and the interdigital electrode 12 includes an interdigital electrode central portion A1 and an interdigital electrode terminal portion A2 .

[0097] Specifically, in this step, Figure 6 The photoresist M is coated and a corresponding photolithography pattern of the interdigital electrodes 12 is formed through mask exposure, development and other processes.

[0098] like Figure 7 As shown, the interdigital electrodes 12 are formed by deposition using a vapor deposition process, including but not limited to; the material of the interdigital electrodes 12 is metal, and can be Ti, Cr, Ag, Cu, Mo, Pt, W, Al or other materials, or a combination of two or more thereof; wherein the interdigital electrodes 12 and the interdigital electrode lead-out portions 16 are prepared in the same process, and the interdigital electrodes 12 and the interdigital electrode lead-out portions 16 are an integrally formed structure.

[0099] like Figure 8 As shown, the process includes but is not limited to using a lift-off process to remove the photoresist M, thereby completing the preparation of the interdigital electrode 12.

[0100] S103: Fig. 9 As shown, a temperature compensation layer 13 is formed on a side of the interdigital electrode 12 facing away from the substrate 11 .

[0101] Specifically, in this step, a temperature compensation layer 13 is deposited and CMP planarization is performed. The temperature compensation layer 13 covers the exposed surfaces of the substrate 11 and the interdigital electrodes 12; the temperature compensation layer 13 can be a single-layer structure of SiO2 material, or a stacked structure of a thin layer of SiN, AlN, amorphous silicon, GaN or other materials superimposed with a thick layer of SiO2, wherein the thin layer of SiN, AlN, amorphous silicon, GaN or other materials can be used as a protective layer for the exposed interdigital electrodes 12 to prevent oxidation of the metal of the interdigital electrodes 12 when SiO2 is deposited.

[0102] S104: Fig.10 As shown, a dielectric layer 14 is formed on a side of the temperature compensation layer 13 facing away from the substrate 11 .

[0103] Specifically, in this step, a dielectric layer 14 is deposited, and the material of the dielectric layer 14 is SiN material, AlN material, amorphous silicon material or GaN material or other insulating materials. In an optional embodiment of the present invention, the dielectric layer 14 includes N layers of sub-dielectric layers stacked in sequence in the first direction; wherein N ≥ 2, and N is a positive integer. Specifically, in the embodiment of the present invention, the number of layers of the dielectric layer 14 is not limited, and it can be a single layer or a multi-layer stacked structure, as long as it can play the role of isolating the metal layer 15 from the temperature compensation layer 13. It should be noted that in the surface acoustic wave resonator, the dielectric layer 14 can also play the role of isolating the metal layer 15 from the temperature compensation layer 13 while realizing some functions that need to be realized.

[0104] S105: Fig.11 and Fig.12 As shown, a metal layer 15 is formed on the side of the dielectric layer 14 away from the substrate 11 , and the orthographic projection of the metal layer 15 in a first direction covers the end portion A2 of the interdigitated electrode; the first direction is perpendicular to the plane where the substrate 11 is located.

[0105] Specifically, in this step, Fig.11 The coated photoresist M shown in the figure forms a corresponding photolithography pattern of the metal layer 15 through mask exposure, development and other processes. The photolithography pattern based on the metal layer 15 includes but is not limited to the metal layer 15 formed by deposition using a vapor deposition process, wherein the metal layer 15 is formed on the surface of the dielectric layer 14, and the orthographic projection of the metal layer 15 in the first direction covers the end portion A2 of the interdigitated electrode; the material of the metal layer 15 can be a metal material, and can optionally be one material such as Ti, Cr, Ag, Cu, Mo, Pt, W, Al, or a combination of two or more of them.

[0106] like Fig.12As shown, the process includes but is not limited to using a lift-off process to remove the photoresist M, thereby completing the preparation of the metal layer 15, and the orthographic projection of the prepared metal layer 15 in the first direction covers the end portion A2 of the interdigital electrode.

[0107] In an optional embodiment of the present invention, Fig.13 and Fig.14 As shown, the method for preparing the surface acoustic wave resonator provided by the embodiment of the present invention also includes:

[0108] The dielectric layer 14 and the temperature compensation layer 13 are etched to form a first through hole penetrating the dielectric layer 14 and the temperature compensation layer 13 .

[0109] A pad structure 17 is formed; the pad structure 17 is electrically connected to the interdigital electrode lead-out portion 16 through the first through hole.

[0110] Specifically, in the embodiment of the present application, two first through holes are included, wherein one first through hole exposes a portion of the surface of the first interdigital electrode lead-out portion 161, and the other first through hole exposes a portion of the surface of the second interdigital electrode lead-out portion 162. The pad structure 17 includes a first pad 171 and a second pad 172, wherein the first pad 171 is in contact and electrically connected with the first interdigital electrode lead-out portion 161 through the corresponding first through hole, and the second pad 172 is in contact and electrically connected with the second interdigital electrode lead-out portion 162 through the corresponding first through hole.

[0111] The material of the pad structure 17 may be a metal material, and may optionally be one material such as Ti, Cr, Al, Cu, Ni, Ag, Au, etc., or a combination of two or more of them.

[0112] In an optional embodiment of the present invention, Fig.15 and Figure 2 As shown, the method for preparing the surface acoustic wave resonator provided by the embodiment of the present invention also includes:

[0113] A passivation layer 18 is formed, and the passivation layer 18 covers the exposed surface of the pad structure 17 , the metal layer 15 , and the dielectric layer 14 . The passivation layer 18 has a second through hole, and the second through hole exposes a portion of the surface of the pad structure 17 .

[0114] Specifically, in the embodiment of the present application, the passivation layer 18 is provided to realize the passivation protection of the surface acoustic wave resonator, thereby improving the performance and service life of the surface acoustic wave resonator. The second through hole is formed by processing the passivation layer 18, exposing a part of the surface of the pad structure 17, so as to realize the electrical connection of the surface acoustic wave resonator to the outside. In other words, the second through hole can be understood as a window for the surface acoustic wave resonator to be electrically connected to the outside.

[0115] It should be noted that the passivation layer 18 can also be used as a frequency adjustment layer of the surface acoustic wave resonator. The material of the passivation layer 18 includes but is not limited to insulating materials such as SiN, AlN, amorphous silicon, GaN, or a combination of two or more of them.

[0116] Optionally, based on the above embodiment of the present invention, a filter is further provided in another embodiment of the present invention. The filter includes the surface acoustic wave resonator described in the above embodiment.

[0117] This filter has the same effect as the surface acoustic wave resonator in the above-mentioned embodiment.

[0118] Optionally, based on the above embodiments of the present invention, in another embodiment of the present invention, an electronic device is further provided, the electronic device includes the filter described in the above embodiments, or includes the surface acoustic wave resonator described in the above embodiments.

[0119] This electronic device has the same effects as the filter or the surface acoustic wave resonator in the above-mentioned embodiments.

[0120] The surface acoustic wave resonator and its preparation method, filter and electronic device provided by the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for general technicians in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

[0121] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0122] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0123] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A surface acoustic wave resonator, characterized in that: The surface acoustic wave resonator comprises: substrate; An interdigital electrode located on one side of the substrate, the interdigital electrode comprising an interdigital electrode central portion and an interdigital electrode terminal portion; a temperature compensation layer located on a side of the interdigital electrode facing away from the substrate; a dielectric layer located on a side of the temperature compensation layer away from the substrate; A metal layer is located on a side of the dielectric layer away from the substrate, and an orthographic projection of the metal layer in a first direction covers the end portion of the interdigitated electrode; the first direction is perpendicular to the plane where the substrate is located.

2. The surface acoustic wave resonator according to claim 1, characterized in that: The metal layer is a metal layer that has been heat-treated in an oxygen-free atmosphere.

3. The surface acoustic wave resonator according to claim 1, characterized in that: The surface acoustic wave resonator further comprises: A dielectric film layer is located on a side of the metal layer facing away from the substrate.

4. The surface acoustic wave resonator according to claim 3, characterized in that: The material of the dielectric film layer is silicon oxide material or silicon nitride material.

5. The surface acoustic wave resonator according to claim 1, characterized in that: The surface acoustic wave resonator further comprises: A transparent conductive electrode layer is located on a side of the metal layer away from the substrate.

6. The surface acoustic wave resonator according to claim 1, characterized in that: The surface acoustic wave resonator further comprises: A metal peroxide layer is located on a side of the metal layer facing away from the substrate.

7. The surface acoustic wave resonator according to claim 1, characterized in that: The surface acoustic wave resonator further comprises: An anti-reflection layer is located on a side of the metal layer facing away from the substrate.

8. The surface acoustic wave resonator according to claim 1, characterized in that: The surface acoustic wave resonator further includes: an interdigital electrode lead-out portion; The interdigital electrode lead-out portion is electrically connected to the interdigital electrode; The surface acoustic wave resonator further includes: a first through hole penetrating the dielectric layer and the temperature compensation layer; The first through hole exposes a portion of the surface of the interdigital electrode lead-out portion; The surface acoustic wave resonator further includes: a pad structure; The pad structure is electrically connected to the interdigital electrode lead-out portion through the first through hole.

9. The surface acoustic wave resonator according to claim 8, characterized in that: The surface acoustic wave resonator further includes: a passivation layer; The passivation layer covers the pad structure, the metal layer and the exposed surface of the dielectric layer; The passivation layer has a second through hole; The second through hole exposes a portion of the surface of the pad structure.

10. The surface acoustic wave resonator according to any one of claims 1 to 9, characterized in that: The material of the dielectric layer is SiN material, AlN material, amorphous silicon material or GaN material.

11. The surface acoustic wave resonator according to any one of claims 1 to 9, characterized in that: The dielectric layer includes N layers of sub-dielectric layers stacked in sequence in the first direction; Wherein, N≥2, and N is a positive integer.

12. A method for preparing a surface acoustic wave resonator, characterized in that: The preparation method of the surface acoustic wave resonator comprises: providing a substrate; forming an interdigital electrode on one side of the substrate, wherein the interdigital electrode comprises an interdigital electrode central portion and an interdigital electrode terminal portion; forming a temperature compensation layer on a side of the interdigital electrode facing away from the substrate; forming a dielectric layer on a side of the temperature compensation layer facing away from the substrate; A metal layer is formed on a side of the dielectric layer facing away from the substrate, and the orthographic projection of the metal layer in a first direction covers the end portion of the interdigital electrode; the first direction is perpendicular to the plane where the substrate is located.

13. A filter, characterized in that: The filter comprises the surface acoustic wave resonator according to any one of claims 1 to 11.

14. An electronic device, characterized in that: The electronic device comprises the surface acoustic wave resonator according to any one of claims 1 to 11; Or, the electronic device comprises the filter according to claim 13.

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