An acoustic resonator

Abstract

The present invention discloses an acoustic resonator and a method for suppressing high-order clutter passbands, providing a substrate on which a reflective grating is formed; a first resonator assembly is formed on the reflective grating, including a first bottom electrode, a first top electrode, and a piezoelectric layer disposed between the first bottom electrode and the first top electrode; a second resonator assembly is formed on the reflective grating and is arranged in parallel with the first resonator assembly, including a second bottom electrode, a second top electrode, and a piezoelectric layer disposed between the first bottom electrode and the first top electrode; the reflective grating includes alternately stacked low acoustic impedance layers and high acoustic impedance layers, and there is a height difference h between the reflective gratings under the first resonator assembly and the second resonator assembly. In the present invention, the height difference h is set in the second layer from top to bottom of the reflective grating, and the height of one side resonator is changed, so that the clutter passbands formed by the frequency offset of the first resonator assembly and the second resonator assembly become superimposed, thereby suppressing the clutter passbands.

Description

Technical Field

[0001] The present invention belongs to the technical field of acoustic wave resonators, and particularly relates to an acoustic wave resonator. Background Art

[0002] Film bulk acoustic resonators typically operate in the resonance mode of the main mode. However, in use, it is often found that in addition to the passband generated by the main mode, passbands of higher-order modes also appear at higher frequencies, which we call clutter. Although these higher-order clutters are very narrow and not obvious, the existence of higher-order clutters still affects the performance of the filter. Some filters of the prior art increase the height of a layer on the top electrode of the parallel resonator to reduce the frequency of the main mode, so as to form a band-pass filter together with the series resonator, but this technique will introduce higher-order clutters; there are also some prior arts that suppress higher-order clutters by reducing the thickness of the top layer of the reflection grating in contact with the bottom of the parallel resonator.

[0003] However, the material of the top layer of the reflection grating is a low acoustic impedance material, usually SiO 2 (silicon dioxide). Since it is close to the resonator, and SiO 2 also plays a role in temperature compensation in the reflection grating. If the thickness of the top SiO 2 is changed to suppress higher-order clutters, the temperature characteristics of the filter will be affected, and it cannot be applied in many industries that are sensitive to temperature and require temperature compensation for filters, such as satellite communication. Summary of the Invention

[0004] To solve the above problems, the present invention provides an acoustic wave resonator.

[0005] The technical solution provided by the present invention is as follows:

[0006] An acoustic wave resonator, comprising:

[0007] a substrate, on which a reflection grating is formed;

[0008] a first resonator assembly, formed on the reflection grating, including a first bottom electrode, a first top electrode, and a piezoelectric layer disposed between the first bottom electrode and the first top electrode;

[0009] a second resonator assembly, formed on the reflection grating, arranged in parallel with the first resonator assembly, including a second bottom electrode, a second top electrode, and a piezoelectric layer disposed between the first bottom electrode and the first top electrode;

[0010] The reflection grating includes alternately stacked low acoustic impedance layers and high acoustic impedance layers. There is a height difference h between the reflection gratings under the first resonator assembly and the second resonator assembly, and the height difference h is set in the second layer from top to bottom of the reflection grating.

[0011] In some embodiments, the material of the low acoustic impedance layer is SiO 2 , and the material of the high acoustic impedance layer is W (tungsten) or Mo (molybdenum).

[0012] In some embodiments, the second layer of the reflection grating under the second resonator assembly sinks with a height difference h.

[0013] In some embodiments, a tuning layer is provided above the second top electrode.

[0014] In some embodiments, the thickness of the reflection grating is 1000 Å - 2 μm.

[0015] In some embodiments, the height of the height difference h is 10 Å - 1000 Å. In some embodiments, the low acoustic impedance layer has 4 layers and the high acoustic impedance layer has 3 layers.

[0016] A method for manufacturing an acoustic wave resonator, including manufacturing an acoustic wave resonator with stable temperature characteristics and low energy loss. The steps are as follows:

[0017] S1: Prepare a substrate, and alternately deposit a low acoustic impedance layer and a high acoustic impedance layer on the substrate to form a reflection grating;

[0018] S2: When depositing to the second layer from top to bottom, etch downward a height difference h on one side of the second layer, and then deposit the topmost layer of the reflection grating on the second layer;

[0019] S3: Fabricate a first resonator assembly and a second resonator assembly on the reflection grating, including fabricating a first bottom electrode and a second bottom electrode on the topmost layer of the reflection grating. The first bottom electrode is disposed on the side of the reflection grating with a higher height, and the second bottom electrode is disposed on the side of the reflection grating with a lower height;

[0020] S4: Fabricate a piezoelectric layer on the first bottom electrode and the second bottom electrode;

[0021] S5: Fabricate a first top electrode and a second top electrode on the piezoelectric layer. The first top electrode is located directly above the first bottom electrode, and the second top electrode is located directly above the second bottom electrode;

[0022] By reducing the thickness of the second layer on one side of the second resonator assembly, a height difference h is generated between the first resonator assembly and the second resonator assembly, so that the main mode frequencies of the first resonator assembly and the second resonator assembly are close to each other, and at the same time, the higher-order frequencies of the first resonator assembly and the second resonator assembly overlap, thereby suppressing the passband of the higher-order clutter.

[0023] In some embodiments, the material of the second layer is W or Mo.

[0024] In some embodiments, a tuning layer is fabricated above the second top electrode in step S5.

[0025] In summary, the beneficial effects of the present invention are as follows:

[0026] (1) A height difference is provided on the second layer of the reflection grating of the present invention, changing the height of one side of the resonator, so that the clutter passbands formed by the frequency offsets of the first resonator assembly and the second resonator assembly become superimposed, thereby suppressing the clutter passbands. At the same time, the performance of the main mode passband is not affected, and setting the height difference on the second layer will not affect the temperature characteristics of the filter, which is applicable to industries that are sensitive to temperature and have temperature compensation requirements for the filter.

[0027] (2) The acoustic wave resonator of the present invention has a height difference provided on the second layer of the reflection grating, which does not affect the dispersion curve of the filter, suppresses the parasitic modes formed below the main mode, and solves the problem of passband jitter.

[0028] (3) The height adjustment of the present invention is provided on the second layer of the reflection grating, and its thickness change has a large sensitivity to frequency. The thickness of the reflection grating can reach the optimal value at the expected thickness, reducing the energy leakage of the resonator, ensuring the Q value, and reducing the loss of the filter. Description of the Drawings

[0029] Figure 1 It is a structural diagram of a resonator in the prior art;

[0030] Figure 2 It is a schematic structural diagram of the present invention;

[0031] Figure 3 It is a schematic structural diagram of the reflection grating of the present invention;

[0032] Figure 4 It is a schematic structural diagram of the filter;

[0033] Figure 5 It is a curve diagram of the impedance characteristics of the series resonator and the parallel resonator in the initial state;

[0034] Figure 6 For Figure 5 An enlarged view of the main passband A in

[0035] Figure 7 For Figure 5 An enlarged view of the parasitic passband B in

[0036] Figure 8 For Figure 5 An enlarged view of E in

[0037] Figure 9 It is the change of the clutter passband when the thickness d changes from 0 to 200 Å in the comparative example;

[0038] Figure 10 It is the change of the main passband bandwidth when the thickness d changes from 0 to 200 Å in the comparative example;

[0039] Figure 11 It is a graph showing the increase in the main resonance frequency of the impedance characteristics of the parallel resonator in the comparative example;

[0040] Figure 12 It is a graph showing the increase in the parasitic resonance frequency of the impedance characteristics of the parallel resonator in the comparative example;

[0041] Figure 13 This is the change of the clutter passband when the height difference h changes from 0 to 100A in this embodiment;

[0042] Figure 14 This is the change of the main passband bandwidth when the height difference h changes from 0 to 100A in this embodiment;

[0043] Figure 15 It is a graph showing the increase in the main resonance frequency of the impedance characteristics of the parallel resonator in this embodiment;

[0044] Figure 16 It is a graph showing the increase in the parasitic resonance frequency of the impedance characteristics of the parallel resonator in this embodiment.

[0045] The reference numerals are as follows:

[0046] 1, substrate; 2, reflection grating;

[0047] 11, first resonator assembly; 12, second resonator assembly; 13, piezoelectric layer; 14, tuning layer; 21, first layer; 22, second layer; 23, third layer; 24, fourth layer; 25, fifth layer; 26, sixth layer; 27, seventh layer;

[0048] 111, first bottom electrode; 112, first top electrode; 121, second bottom electrode; 122, second top electrode; Detailed implementation manners

[0049] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in combination with embodiments. The following embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0050] Based on the research on suppressing high-order clutter, the present invention discovers that in the prior art, by reducing the thickness of the low-impedance layer in contact with the bottom electrode below the parallel resonator, which is usually SiO 2 It can indeed suppress the influence of high-order clutter to a certain extent.

[0051] It is found in the experiment that when changing the thickness of the low-impedance layer SiO 2 layer, since it is close to the resonator, the change in the thickness of SiO 2 affects the temperature characteristics of the filter, resulting in a decrease in its accuracy.

[0052] On the other hand, changing the thickness of the SiO 2 layer will also affect the dispersion curve of the filter. After reducing the thickness, parasitic modes will be formed below the main mode, resulting in jitter in the passband.

[0053] Furthermore, when changing the thickness of the SiO 2 layer, it is found that the change in the main mode frequency f 1 is slightly less different from the change in the high-order mode frequency f 2 . In order to suppress high-order clutter, it is necessary to reduce the thickness of the SiO 2 layer too much, resulting in the thickness of the reflection grating not reaching the set optimal value, which will also cause the Q value to become low, energy leakage of the resonator, and further increase the loss of the filter.

[0054] Among them, in frequency response and resonance phenomena, the "Q value" (Quality Factor, Q) is an important parameter used to describe the sharpness or selectivity of a resonator or filter. The higher the Q value, the sharper the resonance peak, indicating that the system has higher selectivity and a smaller bandwidth near the resonance frequency. On the contrary, a lower Q value indicates a wider resonance peak, lower selectivity, and a larger bandwidth.

[0055] Based on the above experiments, the purpose of this application is to change the height of the height difference h so that the frequency f 2 of the high-order mode changes greatly, while the frequency f 1 of the main mode changes little, in order to suppress the high-order clutter passband while keeping the main bandwidth basically unchanged.

[0056] In the attached figure curve of this application, freq represents frequency; GHz and MHz are frequency units; mag is an abbreviation for magnitude, representing the amplitude of the frequency response, and the amplitude can be expressed in different units, such as decibels (dB) or linear scale; dB is an abbreviation for decibel and represents the amplitude in the frequency response curve.

[0057] Please refer to Figure 1 for reference Figure 2 , Figure 1 which is a schematic diagram of the resonator structure in the prior art. The difference between it and the acoustic wave resonator of this application is that there is no height difference h between the reflection grating 2 under the first resonator component 11 and the second resonator component 12.

[0058] Continuing to refer to Figure 2 , the present invention provides an acoustic wave resonator, including:

[0059] A substrate 1, on which a reflection grating 2 is formed;

[0060] Specifically, the substrate 1 is generally made of silicon, and the reflection grating 2 is grown on the upper surface of the substrate 1. The reflection grating 2 includes alternately stacked low acoustic impedance layers and high acoustic impedance layers. Among them, the low acoustic impedance layer is disposed on the upper surface of the substrate 1, and the topmost layer of the reflection grating 2 is a low acoustic impedance layer, that is, the number of high acoustic impedance layers is one less than the number of low acoustic impedance layers. Please refer to Figure 2 , in this embodiment, the reflection grating 2 is provided with seven layers from 21 to 27. Among them, the first layer 21, the third layer 23, the fifth layer 25, and the seventh layer 27 are low acoustic impedance layers, and their materials are made of SiO 2 ; among them, the second layer 22, the fourth layer 24, and the sixth layer 26 are high acoustic impedance layers, and their materials are made of W. Of course, in other embodiments, other equivalent substitute materials such as Mo and Cr can also be used.

[0061] The first resonator assembly 11 is formed on the reflection grating 2 and includes a first bottom electrode 111, a first top electrode 112, and a piezoelectric layer 13 disposed between the first bottom electrode 111 and the first top electrode 112;

[0062] The second resonator assembly 12 is formed on the reflection grating 2 and is arranged in parallel with the first resonator assembly 11. It includes a second bottom electrode 121, a second top electrode 122, and a piezoelectric layer 13 disposed between the first bottom electrode 111 and the first top electrode 112;

[0063] In this embodiment, the first resonator assembly 11 is a series resonator, and the second resonator assembly 12 is a parallel resonator. The first bottom electrode 111 and the second bottom electrode 121 are disposed on the upper surface of the reflection grating 2, that is, the upper surface of the first layer 21. A piezoelectric layer 13 is provided above the first bottom electrode 111 and the second bottom electrode 121. The piezoelectric layer 13 is composed of crystalline CdS (cadmium sulfide), PZT (lead zirconate titanate piezoelectric ceramic), AlN (aluminum nitride), or ZnO (zinc oxide). A first top electrode 112 and a second top electrode 122 are provided on the upper surface of the piezoelectric layer 13. The first top electrode 112 is located directly above the first bottom electrode 111, and the second top electrode 122 is located directly above the second bottom electrode 121. In order to realize the tuning of the resonator, a tuning layer 14 is provided above the second top electrode 122, and the thickness of the tuning layer 14 determines the bandwidth of the filter.

[0064] Furthermore, in order to suppress the high-order clutter passband, there is a height difference h between the reflection grating 2 below the first resonator assembly 11 and the second resonator assembly 12 of the present invention, that is, by changing the height of one side of the resonator, the clutter passband formed by the frequency separation of the first resonator assembly 11 and the second resonator assembly 12 is made to overlap, thereby suppressing the clutter passband while the main mode passband performance is not affected. In this embodiment, the height difference h is set in the second layer 22 of the reflection grating 2 from top to bottom, and the height difference h is 10 Å - 1000 Å.

[0065] To further verify the effect of the technical solution of the present application on suppressing the high-order clutter passband, please refer to Figure 4 , Figure 4 Figure of the filter structure composed of series resonators X1, X2, X3, X4 and parallel resonators Y1, Y2, Y3. For the impedance characteristic curves of series resonators X1, X2, X3, X4 and parallel resonators Y1, Y2, Y3 in the initial state, please refer to Figure 5 .

[0066] Without suppressing the clutter passband, please refer to Figure 5 , 6 , 7, 8. The main passband is composed of two main resonance peaks at point A in Figure 5 , and the clutter passband is composed of two parasitic resonance peaks at point B in Figure 5 . The principle of suppressing the clutter passband in the present application is as follows: raise the frequency of the series resonance points of parallel resonators Y1, Y2, Y3 (please refer to point m6 in Figure 8 ) to the series resonance points of series resonators X1, X2, X3, X4 (please refer to point m5 in Figure 8 ). In this embodiment, it needs to be shifted upward by 11 MHz, so that X and Y cannot form a clutter passband, thereby achieving the suppression of the clutter passband.

[0067] As a comparative example, in order to suppress the clutter passband, the prior art reduces the thickness d of SiO 2 that is in contact with the bottom electrode of parallel resonators Y1, Y2, Y3. When the thickness d changes from 0 to 200 Å and is recorded every 25 Å, Figure 9 shows the change of the clutter passband. It can be seen that when d = 100 Å, the clutter passband is the weakest. Please continue to refer to Figure 10 . During the process of the thickness d changing from 0 to 200 Å, the bandwidth of the main passband of the filter changes very violently, and the sensitivity reaches 50 kHz / Å. When the clutter passband is the weakest, that is, d = 100 Å, the main bandwidth shrinks by 5 MHz and a side effect of the main passband shift occurs at point C in Figure 10 .

[0068] Please refer to Figure 11 , 12 , Figure 11 shows the curve of the increase in the main resonance frequency of the impedance characteristic of the parallel resonator in the comparative example, Figure 12 shows the curve of the increase in the parasitic resonance frequency of the impedance characteristic of the parallel resonator in the comparative example. When d = 100 Å, Figure 11 shows that the frequency increases from 2.216 GHz to 2.221 GHz, that is, the main resonance frequency of the impedance characteristic of parallel resonators Y1, Y2, Y3 increases by 5 MHz.Figure 12 The displayed frequency increases from 3.223 GHz to 3.234 GHz, that is, the clutter resonance frequency of the impedance characteristics of the parallel resonators Y1, Y2, and Y3 increases by 11 MHz.

[0069] Table 1 shows the parameters of reducing the thickness d of SiO that is in contact with the bottom electrode under the parallel resonator. 2 The detection method of the temperature characteristic TCF is the prior art, and the detection process will not be elaborated in this application. The detection results are recorded in Table 1.

[0070] Table 1

[0071]

[0072] In the embodiment of this application, when reducing the thickness of the second layer 22 of the reflection grating 2 from top to bottom, that is, the height difference h. When h changes from 0 to 100 Å, it is recorded once every 10 Å. Figure 13 The change of the clutter passband is shown. It can be seen that when h = 40 Å, the clutter passband reaches the weakest. Please continue to refer to Figure 14 , during the process of the height difference h changing from 0 to 100 Å, the bandwidth of the main passband of the filter changes insignificantly, and the sensitivity is 12.5 kHz / Å. When the clutter passband reaches the weakest, that is, h = 40 Å, the main bandwidth only shrinks by 0.5 MHz.

[0073] Please refer to Figure 15 , 16 , Figure 15 shows the curve of the increase in the main resonance frequency of the impedance characteristics of the parallel resonator in this embodiment. Figure 16 shows the curve of the increase in the parasitic resonance frequency of the impedance characteristics of the parallel resonator in this embodiment. When h = 40 Å, Figure 15 the displayed frequency increases from 2.216 GHz to 2.2165 GHz, that is, the main resonance frequency of the impedance characteristics of the parallel resonators Y1, Y2, and Y3 increases by 0.5 MHz. Figure 15 the displayed frequency increases from 3.223 GHz to 3.234 GHz, that is, the clutter resonance frequency of the impedance characteristics of the parallel resonators Y1, Y2, and Y3 increases by 11 MHz. Comparing with the method of reducing the thickness of SiO 2 , when the clutter resonance frequency increases by the same frequency, the main resonance frequency of the technical solution of this application only increases by 0.5 MHz, with a significant improvement in effect.

[0074] Table 2 shows the parameters of reducing the thickness of the second layer 22, that is, the height difference h, in this technical solution. The detection method of the temperature characteristic TCF is the prior art, and the detection process will not be elaborated in this application. The detection results are recorded in Table 2.

[0075]

[0076] In summary, in the technical solution of the present application, reducing the thickness of the second layer 22 compared with the method of reducing the thickness of the top layer SiO 2 in the prior art, when the clutter resonance frequency increases by the same frequency, the main resonance frequency of the technical solution of the present application only increases by 0.5 MHz, and the effect of suppressing the clutter passband is significantly improved. Secondly, setting a height difference in the second layer in the technical solution of the present application does not affect the temperature characteristics of the filter, and it is applicable to industries that are sensitive to temperature and have temperature compensation requirements for the filter; at the same time, reducing the thickness reduces the thickness of the reflection grating, and the thickness of the reflection grating can reach the set optimal value, avoiding energy leakage of the resonator.

[0077] On the other hand, the present invention provides a method for suppressing the high-order clutter passband of an acoustic wave resonator, including preparing an acoustic wave resonator, and the steps are as follows:

[0078] S1: Prepare a substrate 1, and alternately deposit a low acoustic impedance layer and a high acoustic impedance layer on the substrate 1 to form a reflection grating 2; specifically in this embodiment, first deposit a layer of SiO 2 on the upper surface of the substrate 1, and then deposit a layer of W on the surface of SiO 2 . Of course, Mo can also be used to replace W, and deposit 3 layers of SiO 2 and 3 layers of W alternately and repeatedly.

[0079] S2: When depositing to the second layer 22 from top to bottom, that is, when depositing to W, etch downward on one side of the second layer 22, and the etching depth is the height difference h. Then deposit a layer of SiO 2 on the second layer 22 to complete the preparation of the reflection grating; for the structure obtained by preparing the above reflection grating 2, please refer to Figure 3 , and the surface of the reflection grating 2 has a structure similar to a step.

[0080] S3: Fabricate a first resonator component 11 and a second resonator component 12 on the reflection grating 2, including fabricating a first bottom electrode 111 and a second bottom electrode 121 on the uppermost layer of the reflection grating 2. The first bottom electrode 111 is disposed on the side of the reflection grating 2 with a higher height, and the second bottom electrode 121 is disposed on the side of the reflection grating 2 with a lower height;

[0081] S4: Fabricate a piezoelectric layer 13 on the first bottom electrode 111 and the second bottom electrode 121;

[0082] S5: Fabricate a first top electrode 112 and a second top electrode 122 on the piezoelectric layer 13. The first top electrode 112 is located directly above the first bottom electrode 111, and the second top electrode 122 is located directly above the second bottom electrode 121. And fabricate a tuning layer 14 above the second top electrode 122;

[0083] The specific implementation method is to reduce the thickness of the second layer 22 on one side of the second resonator component 12, so as to generate a height difference h between the first resonator component 11 and the second resonator component 12, thereby making the main mode frequencies f of the first resonator component 11 and the second resonator component 12 1 approach each other, while the high-order frequencies f of the first resonator component 11 and the second resonator component 12 2 overlap, thereby suppressing the passband of high-order clutter.

[0084] It should be noted that, in the drawings or the text of the specification, the implementation manners that are not illustrated or described are all forms known to those of ordinary skill in the art and are not described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or manners mentioned in the embodiments.

[0085] It should also be noted that the directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", "inside", "outside", etc., are only references to the directions in the drawings and are not used to limit the protection scope of this application.

[0086] The above description shows and describes the preferred embodiments of the present invention. As mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the inventive concept described herein through the above teachings or the techniques or knowledge in the relevant field. And the changes and alterations made by those skilled in the art without departing from the spirit and scope of the present invention should all be within the protection scope of the appended claims of the present invention.

Claims

1. An acoustic wave resonator, characterized in that: include: A substrate (1), wherein a reflection grating (2) is formed on the substrate (1); A first resonator component (11), formed on the reflection grid (2), comprising a first bottom electrode (111), a first top electrode (112), and a piezoelectric layer (13) arranged between the first bottom electrode (111) and the first top electrode (112); A second resonator component (12) is formed on the reflection grid (2), arranged in parallel with the first resonator component (11), and comprises a second bottom electrode (121), a second top electrode (122), and a piezoelectric layer (13) arranged between the first bottom electrode (111) and the first top electrode (112); The reflection grating (2) comprises alternately stacked low acoustic impedance layers and high acoustic impedance layers, and there is a height difference h between the first resonator component (11) and the reflection grating (2) below the second resonator component (12), and the height difference h is set at the second layer (22) from top to bottom of the reflection grating (2); The material of the low acoustic impedance layer is SiO2, the material of the high acoustic impedance layer is W or Mo, and the material of the second layer (22) is W or Mo; The second layer (22) of the reflective grating (2) below the second resonator component (12) is sunken with a height difference h; The height difference h is 40A; The preparation steps of the acoustic wave resonator are: S1: preparing a substrate (1), and alternately depositing low acoustic impedance layers and high acoustic impedance layers on the substrate (1) to form a reflection grating (2); S2: when depositing to the second layer (22) from top to bottom, etching downwards a height difference h on one side of the second layer (22), and then depositing the uppermost layer of the reflective grating (2) on the second layer (22); S3: manufacturing a first resonator component (11) and a second resonator component (12) on the reflection grid (2), comprising manufacturing a first bottom electrode (111) and a second bottom electrode (121) on the uppermost layer of the reflection grid (2), wherein the first bottom electrode (111) is arranged on a side of the reflection grid (2) with a higher height, and the second bottom electrode (121) is arranged on a side of the reflection grid (2) with a lower height; S4: forming a piezoelectric layer (13) on the first bottom electrode (111) and the second bottom electrode (121); S5: manufacturing a first top electrode (112) and a second top electrode (122) on the piezoelectric layer (13), wherein the first top electrode (112) is located directly above the first bottom electrode (111), and the second top electrode (122) is located directly above the second bottom electrode (121); By reducing the thickness of the second layer (22) on one side of the second resonator component (12), a height difference h is generated between the first resonator component (11) and the second resonator component (12), so that the main mode frequencies of the first resonator component (11) and the second resonator component (12) are close to each other, and the high-order frequencies of the first resonator component (11) and the second resonator component (12) are overlapped, thereby suppressing the passband of high-order clutter; The material of the second layer (22) is W or Mo; A tuning layer (14) is fabricated above the second top electrode (122) in step S5.

2. The acoustic wave resonator according to claim 1, characterized in that A tuning layer (14) is provided above the second top electrode (122).

3. The acoustic wave resonator according to claim 1, characterized in that The thickness of the reflective grating (2) is 1000A-2 μm.

4. The acoustic wave resonator according to claim 1, characterized in that The low acoustic impedance layer is provided with four layers, and the high acoustic impedance layer is provided with three layers.

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