Surface acoustic wave resonator and manufacturing method thereof

Abstract

The invention provides a surface acoustic wave resonator and a manufacturing method thereof, and the method comprises the steps: providing a substrate, and forming a piezoelectric layer on the surface of the substrate; an interdigital transducer is formed on the piezoelectric layer, the interdigital transducer comprises a first finger electrode and a second finger electrode which are arranged in a crossed mode, each of the first finger electrode and the second finger electrode comprises a bus bar and a plurality of electrode fingers connected with the bus bar, and the electrode fingers are arranged at intervals in the first direction; forming a temperature compensation layer with a predetermined target thickness to cover the surface of the interdigital transducer; and finishing the thickness of the temperature compensation layer to adjust the frequency of the surface acoustic wave resonator. According to the method, after the temperature compensation layer is formed, the thickness of the temperature compensation layer is trimmed, so that the purpose of frequency modulation is achieved, and the method is high in reliability.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a surface acoustic wave resonator and a manufacturing method thereof. Background Art

[0002] Surface Acoustic Wave (SAW) resonator is an electronic component that converts electrical signals into acoustic signals or acoustic signals into electrical signals. It is widely used to screen and output electrical signals in a specific frequency range to achieve accurate signal processing and transmission. SAW resonators usually include a piezoelectric layer and an interdigital transducer (IDT) formed on the piezoelectric layer. The interdigital transducer can be used to convert electrical signals into acoustic signals or acoustic signals into electrical signals.

[0003] The frequency of the SAW resonator is closely related to the spacing between the metal interdigital electrodes of the interdigital transducer. After the IDT is prepared, a temperature compensation layer, SIN and other film layers of fixed thickness can usually be grown on the surface of the IDT to protect the IDT. Such film layers have a certain influence on the frequency of the SAW resonator. Therefore, how to adjust these film layers so that the frequency of the SAW resonator meets the design requirements is a problem that needs to be solved urgently. Summary of the invention

[0004] A series of simplified concepts are introduced in the summary of the invention, which will be further described in detail in the specific implementation method. The summary of the invention does not mean to attempt to define the key features and essential technical features of the technical solution claimed for protection, nor does it mean to attempt to determine the scope of protection of the technical solution claimed for protection.

[0005] In view of the existing problems, the present invention provides a method for manufacturing a surface acoustic wave resonator, comprising: providing a substrate, wherein a piezoelectric layer is formed on a surface of the substrate; An interdigital transducer is formed on the piezoelectric layer, wherein the interdigital transducer comprises a first finger electrode and a second finger electrode arranged crosswise, each of the first finger electrode and the second finger electrode comprises a bus bar and a plurality of electrode fingers connected to the bus bar, and the plurality of electrode fingers are arranged at intervals in a first direction; Forming a temperature compensation layer with a predetermined target thickness to cover the surface of the interdigital transducer; The thickness of the temperature compensation layer is trimmed to adjust the frequency of the surface acoustic wave resonator.

[0006] In one example, the thickness of the temperature compensation layer is trimmed to adjust the frequency of the surface acoustic wave resonator, including: Acquire a target size of the electrode finger in the first direction and measure an actual size of the electrode finger in the first direction; Obtaining the target thickness of the electrode fingers and measuring the actual thickness of the electrode fingers; Determining a target frequency modulation thickness of the temperature compensation layer based on the target size, the actual size, the target thickness, the actual thickness, and the predetermined target thickness; The thickness of the temperature compensation layer is trimmed to a target frequency tuning thickness to adjust the frequency of the surface acoustic wave resonator.

[0007] In one example, determining a target frequency modulation thickness of the temperature compensation layer based on the target size, the actual size, the target thickness, the actual thickness, and the predetermined target thickness includes: The target frequency modulation thickness of the temperature compensation layer is determined based on the following formula, Among them, T1 is the target FM thickness, W1 is the actual size, W2 is the target size, T2 is the actual thickness, T3 is the target thickness, and T4 is the predetermined target thickness.

[0008] In one example, the size of the electrode fingers and the frequency of the SAW resonator are linearly and negatively correlated; The thickness of the electrode finger is linearly related to the frequency of the surface acoustic wave resonator and negatively correlated; the thickness of the temperature compensation layer is linearly related to the frequency of the surface acoustic wave resonator and negatively correlated; The thickness of the cover layer is linearly and negatively correlated with the frequency of the SAW resonator.

[0009] In one example, the substrate includes a plurality of exposure regions, each exposure region is used to form at least one surface acoustic wave resonator, and the thickness of the temperature compensation layer is trimmed to adjust the frequency of the surface acoustic wave resonator, including: The thickness of the temperature compensation layer corresponding to each exposure area is trimmed respectively to adjust the frequency of the corresponding surface acoustic wave resonator.

[0010] In one example, the temperature compensation layers in at least two exposure regions correspond to different target frequency modulation thicknesses.

[0011] In one example, the thickness of the temperature compensation layer is trimmed by etching.

[0012] In one example, the material of the temperature compensation layer includes silicon oxide.

[0013] In one example, the method further includes: forming a capping layer on the temperature compensation layer, wherein a material of the capping layer includes silicon nitride or silicon nitride oxide.

[0014] Another aspect of the present invention provides a surface acoustic wave resonator obtained by the above-mentioned manufacturing method.

[0015] The surface acoustic wave resonator and the manufacturing method thereof of the present invention adjust the thickness of the temperature compensation layer after forming the temperature compensation layer, so that the frequency of the surface acoustic wave resonator approaches or reaches the design frequency, thereby ensuring that the resonator resonates within a predetermined frequency range, thereby effectively transmitting or suppressing signals within the predetermined frequency range. Moreover, compared with the frequency modulation method of trimming the cover layer in the related art, the method of the present application has higher reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following drawings of the present invention are used to understand the present invention as part of the present invention. The embodiments of the present invention are shown in the drawings and the description thereof is used to explain the principle of the present invention.

[0017] In the attached figure: Figure 1 A flow chart showing a method for manufacturing a surface acoustic wave resonator according to a specific embodiment of the present invention; Figure 2 A schematic cross-sectional view of a surface acoustic wave resonator according to a specific embodiment of the present invention is shown; Figure 3 A schematic diagram showing the relationship between the size of the electrode finger of a surface acoustic wave resonator in a first direction and the frequency of the surface acoustic wave resonator according to a specific embodiment of the present invention; Figure 4 A schematic diagram showing the relationship between the thickness of the electrode fingers of a surface acoustic wave resonator and the frequency of the surface acoustic wave resonator according to a specific embodiment of the present invention; Figure 5 A schematic diagram showing the relationship between the thickness of the temperature compensation layer of a surface acoustic wave resonator and the frequency of the surface acoustic wave resonator according to a specific embodiment of the present invention; Figure 6 A schematic diagram showing the relationship between the thickness of the cover layer of a surface acoustic wave resonator and the frequency of the surface acoustic wave resonator according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0018] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0019] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0020] 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.

[0021] 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.

[0022] 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 "a", "an" and " / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the terms "consisting of" and / or "comprising" when used in this specification determine the presence of 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.

[0023] In order to fully understand the present invention, detailed steps and structures will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0024] In view of the above technical problems, the present invention provides a method for manufacturing a surface acoustic wave resonator, such as Figure 1 As shown, the manufacturing method 100 includes the following steps: In step S110, a substrate is provided, and a piezoelectric layer is formed on a surface of the substrate; In step S120, an IDT is formed on the piezoelectric layer, wherein the IDT comprises a first finger electrode and a second finger electrode arranged crosswise, each of the first finger electrode and the second finger electrode comprises a bus bar and a plurality of electrode fingers connected to the bus bar, and the plurality of electrode fingers are arranged at intervals in a first direction; In step S130, a temperature compensation layer with a predetermined target thickness is formed to cover the surface of the IDT; In step S140 , the thickness of the temperature compensation layer is trimmed to adjust the frequency of the surface acoustic wave resonator.

[0025] The method for manufacturing a surface acoustic wave resonator of the present invention achieves the purpose of frequency modulation by trimming the thickness of the temperature compensation layer after forming the temperature compensation layer, so that the frequency of the surface acoustic wave resonator approaches or reaches the design frequency, thereby ensuring that the resonator resonates within a predetermined frequency range, thereby effectively transmitting or suppressing signals within the predetermined frequency range. Moreover, compared with the frequency modulation method of trimming the cover layer in the related art, the method of the present application has higher reliability.

[0026] Reference below Figure 1 , Figure 2 as well as Figures 3 to 6 The method for manufacturing the surface acoustic wave resonator of the present invention is explained and illustrated in detail.

[0027] First, execute step S110, such as Figure 2As shown, a substrate 200 is provided, and a piezoelectric layer 210 is formed on the surface of the substrate 200 .

[0028] The substrate 200 is used to provide a process platform for the subsequent formation of resonators. A resonator refers to a device that generates a resonant frequency. In this embodiment, the substrate 200 is a wafer. By making the resonator on a wafer, the process cost can be reduced and mass production can be achieved, which is conducive to improving the reliability of the resonator and improving the manufacturing efficiency.

[0029] The substrate 200 may be a piezoelectric substrate, so that the subsequent resonator can use the piezoelectric effect for filtering. In this embodiment, the material of the substrate 200 is lithium niobate (LiNbO3), lithium tantalate (LiTaO3), quartz or piezoelectric ceramics. Among them, lithium niobate or lithium tantalate can provide a very high electromechanical coupling coefficient and can be used to manufacture a filter with a relative bandwidth of about 50%.

[0030] Optionally, the material of the piezoelectric layer 210 may include one or more of LiNbO 3 , LiTaO 3 , and quartz.

[0031] Next, in step S120, continue to refer to Figure 2 , an interdigital transducer is formed on the piezoelectric layer 210, wherein the interdigital transducer includes a first finger electrode and a second finger electrode arranged crosswise, the first finger electrode and the second finger electrode both include a bus bar and a plurality of electrode fingers 220 connected to the bus bar, and the plurality of electrode fingers 220 are arranged at intervals in a first direction.

[0032] The interdigital transducer is used to realize the mutual conversion between electrical signals and acoustic signals, so that the resonator can filter the signal. Specifically, the interdigital transducer is an acoustic transducer with a piezoelectric structure. The interdigital transducer can be a metal interdigital transducer. IDT includes two groups of first finger electrodes and second finger electrodes with energy conversion functions, which are input interdigital transducers and output interdigital transducers respectively. When the input interdigital transducer receives an electrical signal, the surface of the substrate 200 vibrates and excites an acoustic wave with the same frequency as the external signal. The acoustic wave propagates along the direction of the surface of the piezoelectric substrate, and a part of the acoustic wave is transmitted to the output interdigital transducer. The output interdigital transducer converts the mechanical vibration into an electrical signal, which is output by the output interdigital transducer.

[0033] In some examples, the material of the first finger electrodes includes one or more of Mo, Al, Pt, W, Au, Al, Cu, Cr, Ti, Ni, and Ag. The material of the second finger electrodes includes one or more of Mo, Al, Pt, W, Au, Cu, Cr, Ti, Al, Ni, and Ag.

[0034] In this embodiment, the first finger electrode and the second finger electrode may be interdigital aluminum electrodes. Specifically, in some examples, a metal film may be deposited on the piezoelectric layer 210, and the metal film may be patterned by photolithography and etching processes to form an interdigital transducer, and the method for forming the metal film may be physical vapor deposition or any other suitable deposition method.

[0035] Optionally, the first finger electrode and the second finger electrode both include a bus bar and a plurality of electrode fingers 220 connected to the bus bar, the plurality of electrode fingers 220 are spaced apart in a first direction, that is, spaced apart in a length direction of the bus bar, each electrode finger 220 extends in a second direction, and the first direction and the second direction are substantially perpendicular.

[0036] The first finger electrode and the second finger electrode are cross-arranged, that is, the first finger electrode and the second finger electrode are arranged in a forked finger shape, so that the electrode fingers 220 of the first finger electrode and the electrode fingers 220 of the second finger electrode are alternately arranged along a first direction, and the first direction is parallel to the surface of the piezoelectric layer 210 close to the side of the forked finger transducer.

[0037] The number of electrode fingers 220 included in the first finger-shaped electrode may be the same as or different from the number of electrode fingers 220 included in the second finger-shaped electrode.

[0038] The plurality of electrode fingers 220 in the first finger-shaped electrode may be arranged at equal intervals or at unequal intervals along the first direction. Similarly, the plurality of electrode fingers 220 in the second finger-shaped electrode may be arranged at equal intervals or at unequal intervals along the first direction.

[0039] In addition, the spacing between the electrode fingers 220 of each pair of adjacent first finger electrodes and the electrode fingers 220 of the second finger electrodes may be equal or unequal. The embodiments of the present application do not limit the structural design of the interdigital transducer.

[0040] In order to make the frequency of the surface acoustic wave resonator close to or reach the design frequency (also referred to as the target frequency in this article), before forming the IDT, it is usually necessary to first determine the target size and target thickness of the electrode fingers 220 of the IDT according to the target frequency, such as Figure 3As shown, the size of the electrode finger 220 and the frequency of the surface acoustic wave resonator are linearly related, wherein the frequency and the size of the electrode finger 220 are negatively correlated, and the size is also the size of the electrode finger 220 in the first direction, which can be called a critical dimension (Critical Dimension, CD for short). For example, the relationship between the size of the electrode finger 220 and the frequency of the surface acoustic wave resonator satisfies the following formula: Y=-0.0336X+757.35 Formula (1) Here, Y represents the frequency, and X represents the size of the electrode finger 220 .

[0041] The above formula (1) can be obtained by linearly fitting the previously acquired sizes of the plurality of electrode fingers 220 and the corresponding frequencies of the surface acoustic wave resonators. The R 2 (coefficient of determination) is a statistic that measures how well the model fits the observed data. ‌R 2 It indicates the percentage of variance of the dependent variable explained by the independent variables, and its value is between 0 and 100%. 2 A higher value means that the model is better able to explain the variation in the dependent variable, while a lower R 2 The value indicates that the model has weak explanatory power. 2 The linear fitting model is 0.8581, which can better explain the variation of the dependent variable.

[0042] like Figure 4 As shown, the thickness of the electrode finger 220 and the frequency of the surface acoustic wave resonator are linearly related, wherein the frequency and the thickness of the electrode finger 220 are negatively correlated. For example, the relationship between the thickness of the electrode finger 220 and the frequency of the surface acoustic wave resonator satisfies the following formula: Y=-0.0202X+881.04 Formula (2) Here, Y represents the frequency, and X represents the thickness of the electrode finger 220 .

[0043] Similarly, the above formula (2) can also be obtained by linearly fitting the thickness of the plurality of electrode fingers 220 previously obtained and the frequency of the corresponding surface acoustic wave resonator. The R of the linear fitting is 2 The linear fitting model is 0.9707, which can better explain the variation of the dependent variable.

[0044] Specifically, the target size and target thickness of the electrode finger 220 can be determined according to the target frequency using the above formula, or the target size and target thickness of the electrode finger 220 corresponding to the target frequency can be directly obtained based on prior experience, and then the metal layer is deposited based on the target size and target thickness. However, due to certain process deviations in the deposition process or the etching process, there may be deviations between the size of the electrode finger 220 actually obtained and the target size, and there may be deviations between the thickness of the electrode finger 220 and the target thickness. If not processed, these deviations may cause deviations between the actual frequency of the surface acoustic wave resonator and the target frequency, thereby affecting the normal operation of the resonator.

[0045] Optionally, the size of the electrode finger 220 may range from 688 Å to 1280 Å, which may be adjusted according to the frequency range. Optionally, the thickness of the electrode finger 220 may range from 2750 Å to 3300 Å, which may be adjusted according to the frequency range.

[0046] Next, in step S130, continue to refer to Figure 2 A temperature compensation layer 230 with a predetermined target thickness is formed to cover the surface of the IDT.

[0047] In order to make the frequency of the surface acoustic wave resonator close to or reach the design frequency (also referred to as the target frequency herein), it is usually necessary to first determine the predetermined target thickness of the temperature compensation layer 230 according to the target frequency before forming the temperature compensation layer 230. The predetermined target thickness of the temperature compensation layer 230 can be determined according to the target frequency by the following formula (3), or the predetermined target thickness of the temperature compensation layer 230 corresponding to the target frequency can be directly obtained based on prior experience. In some embodiments, the numerical range of the predetermined target thickness can be 9490Å-12570Å, or other suitable numerical ranges.

[0048] like Figure 5 As shown, the thickness of the temperature compensation layer 230 and the frequency of the surface acoustic wave resonator are linearly related, wherein the thickness of the temperature compensation layer 230 and the frequency of the surface acoustic wave resonator are negatively correlated. For example, the relationship between the thickness of the temperature compensation layer 230 and the frequency of the surface acoustic wave resonator satisfies the following formula: Y=-0.004X+873.76 Formula (3) Wherein, Y represents the frequency, and X represents the thickness of the temperature compensation layer 230 .

[0049] The above formula (3) can be obtained by linearly fitting the previously acquired thickness of the temperature compensation layer 230 and the corresponding frequency of the surface acoustic wave resonator. The R 2 The linear fitting model is 0.9379, which can better explain the variation of the dependent variable.

[0050] In some embodiments, the predetermined target thickness may also have a predetermined margin space, so as to achieve the purpose of frequency modulation by trimming the temperature compensation layer 230. For example, the predetermined thickness may be increased on the basis of the thickness determined by formula (3), so as to allow a larger margin for subsequent trimming and improve the reliability of trimming. The predetermined thickness may be reasonably set according to actual needs, for example, it may be 100 Å-650 Å, and no specific limitation is made here.

[0051] In some embodiments, the temperature compensation layer 230 is used to adjust the temperature frequency coefficient of the resonator to avoid changes in the resonant frequency of the resonator due to temperature changes. The temperature compensation layer 230 may have a positive temperature coefficient to compensate for the negative temperature coefficient of the piezoelectric layer 210. The material of the temperature compensation layer 230 includes but is not limited to silicon oxide, fluorine-containing silicon dioxide, etc.

[0052] The temperature compensation layer 230 is located in the area between the two bus bars and covers the surfaces of the multiple electrode fingers 220. That is, the temperature compensation layer 230 can be located between the two bus bars and cover the multiple electrode fingers 220 and the piezoelectric layer 210 between the two bus bars. This method can improve the Q value of the resonator. In some other embodiments, the temperature compensation layer 230 can also cover two bus bars on the basis of covering the surfaces of the multiple electrode fingers 220. Specifically, it can cover one of the bus bars, or it can cover two bus bars, it can cover a part of the bus bar, or it can cover the entire bus bar, which is not limited in this application.

[0053] The temperature compensation layer 230 may be formed by, for example, chemical vapor deposition, physical vapor deposition, or any other suitable deposition method.

[0054] Next, in step S140, continue to refer to Figure 2 , the thickness of the temperature compensation layer 230 is trimmed to adjust the frequency of the surface acoustic wave resonator.

[0055] In some embodiments, the thickness of the temperature compensation layer 230 is trimmed to adjust the frequency of the surface acoustic wave resonator, including: obtaining a target size of the electrode finger 220 in the first direction and measuring the actual size of the electrode finger 220 in the first direction; obtaining a target thickness of the electrode finger 220 and measuring the actual thickness of the electrode finger 220; determining a target frequency modulation thickness of the temperature compensation layer 230 based on the target size of the electrode finger 220, the actual size of the electrode finger 220, the target thickness of the electrode finger 220, the actual thickness of the electrode finger 220 and the predetermined target thickness of the temperature compensation layer 230; trimming the thickness of the temperature compensation layer 230 to the target frequency modulation thickness to adjust the frequency of the surface acoustic wave resonator, for example, adjusting the frequency of the surface acoustic wave resonator to make it close to or reach the target frequency, thereby ensuring that the resonator resonates within a predetermined frequency range, thereby effectively transmitting or suppressing signals within the predetermined frequency range.

[0056] In some embodiments, the target frequency modulation thickness of the temperature compensation layer 230 is determined based on the following formula: Formula (4)

[0057] Among them, T1 is the target frequency modulation thickness of the electrode finger 220, W1 is the actual size of the electrode finger 220, W2 is the target size of the electrode finger 220, T2 is the actual thickness of the electrode finger 220, T3 is the target thickness of the electrode finger 220, and T4 is the predetermined target thickness of the temperature compensation layer 230.

[0058] The above formula (4) can be derived based on the above formulas 1-3.

[0059] In some embodiments, the substrate 200 of the present application may be a wafer, which may include a plurality of exposure regions, each exposure region (shot) is used to form at least one surface acoustic wave resonator, and the thickness of the temperature compensation layer 230 is trimmed to adjust the frequency of the surface acoustic wave resonator, including: trimming the thickness of the temperature compensation layer 230 corresponding to each exposure region respectively to adjust the frequency of the corresponding surface acoustic wave resonator. For example, the target frequency modulation thickness of each exposure region is determined by the aforementioned method, and then the thickness of the temperature compensation layer 230 of the exposure region is trimmed to the corresponding target frequency modulation thickness. Since the process deviation may be different at different positions of the substrate 200, the actual thickness or actual size of the electrode finger 220 may also be different, which may cause the temperature compensation layer 230 of at least two exposure regions to correspond to different target frequency modulation thicknesses, for example, all exposure regions correspond to different target frequency modulation thicknesses, or part of the exposure regions correspond to different target frequency modulation thicknesses.

[0060] By sequentially trimming the temperature compensation layer 230 in a plurality of exposure regions, the frequency of the surface acoustic wave resonator on the entire substrate 200 can be adjusted.

[0061] In some embodiments, the thickness of the temperature compensation layer 230 is trimmed by etching, for example, by dry etching or wet etching to remove a portion of the temperature compensation layer 230. Preferably, a dry etching process is used, and dry etching includes but is not limited to: reactive ion etching (RIE), ion beam etching, and plasma etching.

[0062] Next, in some embodiments, the manufacturing method of the present application further includes step S150. In step S150, continue to refer to Figure 2 , a capping layer 240 is formed on the temperature compensation layer 230 .

[0063] The covering layer 240 can be arranged on the surface of the temperature compensation layer 230 away from the IDT, and the covering layer 240 can be used to adjust the resonant frequency of the resonator. Optionally, the material of the covering layer 240 can be silicon nitride or silicon oxynitride. The covering layer 240 can be a single layer or a multilayer, and different materials can be used between the multilayers. The covering layer 240 can be used to adjust the resonant frequency of the resonator. The covering layer 240 can also play a passivation role to protect the IDT, which helps to prevent the IDT from being damaged or corroded.

[0064] The capping layer 240 may be formed by, for example, chemical vapor deposition, physical vapor deposition, or any other suitable deposition method.

[0065] Optionally, the thickness of the covering layer 240 may be less than the thickness of the temperature compensation layer 230. Therefore, the method of adjusting the frequency by trimming the thinner covering layer 240 in the related art has a high reliability risk. Therefore, in the embodiment of the present application, a covering layer 240 of a predetermined thickness may be deposited to cover the temperature compensation layer 230. The predetermined thickness may be reasonably set according to actual needs, or may be an empirical value or may be determined according to the target frequency. The predetermined thickness may be a fixed value determined according to the frequency. By depositing a covering layer 240 of a fixed thickness, the reliability risk brought about by trimming the covering layer 240 in the related art may be reduced, and the trimming process of the covering layer 240 may also be reduced, thereby optimizing the process flow of the resonator.

[0066] like Figure 6 As shown, the thickness of the cover layer 240 and the frequency of the surface acoustic wave resonator are linearly related, wherein the thickness of the cover layer 240 and the frequency of the surface acoustic wave resonator are negatively correlated. For example, the relationship between the thickness of the cover layer 240 and the frequency of the surface acoustic wave resonator satisfies the following formula: Y=-0.0192X+922.07 Formula (5) Here, Y represents the frequency, and X represents the thickness of the cover layer 240 .

[0067] The above formula (5) can be obtained by linearly fitting the frequencies of the previously acquired multiple cover layers 240 and the corresponding surface acoustic wave resonators. The R 2 The linear fitting model is 0.9512, which can better explain the variation of the dependent variable.

[0068] Exemplarily, the thickness of the cover layer 240 ranges from 150Å to 450Å. For example, the thickness of the cover layer 240 may be 150Å, 200Å, 250Å, 300Å, 400Å, or 450Å, or any other suitable thickness. Different target frequencies may correspond to different thicknesses of the cover layer 240 .

[0069] After that, continue to refer to Figure 2 The manufacturing method of the embodiment of the present application may further include the step of forming a first conductive structure 251 and a second conductive structure 252, wherein the first conductive structure 251 and the second conductive structure 252 also penetrate the piezoelectric layer 210, wherein the first conductive structure 251 and the second conductive structure 252 may be wiring pads, which may be used to electrically connect to the aforementioned first finger electrode and the second finger electrode, respectively, so as to achieve electrical connection with an external circuit through the wiring pads.

[0070] This completes the introduction to the manufacturing method of the surface acoustic wave resonator of the embodiment of the present application, but it should be understood that the completed device manufacturing may also include more steps, and, under the premise of no conflict, the order of the process steps of the present application may also be reasonably adjusted according to actual needs.

[0071] On the other hand, the present invention further provides a surface acoustic wave resonator, which can be prepared by the method of the above embodiment and also has the advantages of the above embodiment.

[0072] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for manufacturing a surface acoustic wave resonator, characterized in that: include: providing a substrate, wherein a piezoelectric layer is formed on a surface of the substrate; An interdigital transducer is formed on the piezoelectric layer, wherein the interdigital transducer comprises a first finger electrode and a second finger electrode arranged crosswise, the first finger electrode and the second finger electrode each comprise a bus bar and a plurality of electrode fingers connected to the bus bar, and the plurality of electrode fingers are arranged at intervals in a first direction; Forming a temperature compensation layer with a predetermined target thickness to cover the surface of the interdigital transducer; The thickness of the temperature compensation layer is trimmed to adjust the frequency of the surface acoustic wave resonator.

2. The manufacturing method according to claim 1, characterized in that The thickness of the temperature compensation layer is trimmed to adjust the frequency of the surface acoustic wave resonator, comprising: Acquiring a target size of the electrode finger in the first direction and measuring an actual size of the electrode finger in the first direction; Obtaining a target thickness of the electrode finger and measuring an actual thickness of the electrode finger; Determining a target frequency modulation thickness of the temperature compensation layer based on the target size, the actual size, the target thickness, the actual thickness, and the predetermined target thickness; The thickness of the temperature compensation layer is trimmed to the target frequency tuning thickness to adjust the frequency of the surface acoustic wave resonator.

3. The manufacturing method according to claim 2, characterized in that: The step of determining a target frequency modulation thickness of the temperature compensation layer based on the target size, the actual size, the target thickness, the actual thickness, and the predetermined target thickness includes: The target frequency modulation thickness of the temperature compensation layer is determined based on the following formula: ， Among them, T1 is the target frequency modulation thickness, W1 is the actual size, W2 is the target size, T2 is the actual thickness, T3 is the target thickness, and T4 is the predetermined target thickness.

4. The manufacturing method according to claim 2, characterized in that: The size of the electrode finger is linearly and negatively correlated with the frequency of the surface acoustic wave resonator; The thickness of the electrode finger is linearly related to the frequency of the surface acoustic wave resonator and negatively correlated; the thickness of the temperature compensation layer is linearly related to the frequency of the surface acoustic wave resonator and negatively correlated; The thickness of the cover layer and the frequency of the surface acoustic wave resonator are linearly and negatively correlated.

5. The manufacturing method according to claim 2, characterized in that: The substrate includes a plurality of exposure regions, each of which is used to form at least one surface acoustic wave resonator, and the thickness of the temperature compensation layer is trimmed to adjust the frequency of the surface acoustic wave resonator, including: The thickness of the temperature compensation layer corresponding to each of the exposure regions is trimmed respectively to adjust the frequency of the corresponding surface acoustic wave resonator.

6. The manufacturing method according to claim 5, characterized in that: The temperature compensation layers in at least two of the exposure areas correspond to different target frequency modulation thicknesses.

7. The manufacturing method according to any one of claims 1 to 6, characterized in that: The thickness of the temperature compensation layer is trimmed by etching.

8. The manufacturing method according to any one of claims 1 to 6, characterized in that: The material of the temperature compensation layer includes silicon oxide.

9. The manufacturing method according to any one of claims 1 to 6, characterized in that: Also includes: A capping layer is formed on the temperature compensation layer, wherein a material of the capping layer includes silicon nitride or silicon nitride oxide.

10. A surface acoustic wave resonator obtained by the manufacturing method according to any one of claims 1 to 9.

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