Interdigital bulk acoustic wave resonator and filter

Abstract

An interdigital BAW resonator and filter relate to the field of resonator technology. The interdigital BAW resonator comprises a substrate and a piezoelectric stack located on the substrate. The piezoelectric stack comprises a piezoelectric layer located on the substrate and a first set of interdigital electrodes and a second set of interdigital electrodes located on the piezoelectric layer. A cavity is provided on the side of the substrate adjacent to the piezoelectric stack. The first set of interdigital electrodes and the second set of interdigital electrodes each comprise a plurality of first electrodes, with at least two of the first electrodes having different heights on the piezoelectric layer. The interdigital BAW resonator can achieve independent tuning of each mode of a multi-mode resonator by providing multiple arrays of interdigital fingers of different heights.

Description

Technical Field

[0001] The present invention relates to the technical field of resonators, and in particular to an interdigital bulk acoustic wave resonator and a filter. Background Art

[0002] With the rapid development of multi-band wireless communication technology, the demand for highly integrated and miniaturized RF front-end devices has become increasingly prominent. Dual-band filters and multi-band filters, which are front-end devices of wireless communication systems, have gradually become indispensable components in communication systems due to their high selectivity, small size, low cost, and ability to operate simultaneously in multiple communication frequency bands.

[0003] Traditional dual-passband filters and multi-passband filters are usually implemented by connecting multiple single-passband filters in series, or using multi-mode resonators. However, the method of designing a multi-passband filter by connecting multiple single-passband filters in series, although it is possible to adjust the bandwidth, quality factor and other parameters of a single passband individually, its physical size is generally large; and the method of designing a multi-passband filter by using multi-mode resonators, although it is possible to achieve a smaller physical size, conventional multi-mode resonators need to use multiple propagation modes of bulk acoustic waves at the same time, and bulk acoustic waves of different propagation modes have different propagation forms, propagation paths and propagation speeds. Therefore, the bandwidth, quality factor and other parameters of each resonant mode of the multi-mode resonator can only be adjusted within a certain range, which has certain limitations. Therefore, how to reduce the physical volume of dual-passband filters and multi-passband filters, and how to achieve independent tuning of multiple modes so that the multiple modes do not interfere with each other has become a technical problem that needs to be solved urgently. Summary of the Invention

[0004] The object of the present invention is to provide an interdigital bulk acoustic wave resonator and a filter, which can achieve independent tuning of each mode of a multi-mode resonator by arranging multiple interdigital arrays of different heights.

[0005] The embodiment of the present invention is achieved as follows:

[0006] One aspect of the present invention provides an IBAW resonator (IBAW) comprising a substrate and a piezoelectric stack located on the substrate. The piezoelectric stack comprises a piezoelectric layer located on the substrate and a first set of interdigital electrodes and a second set of interdigital electrodes located on the piezoelectric layer. A cavity is provided on the side of the substrate proximal to the piezoelectric stack. The first set of interdigital electrodes and the second set of interdigital electrodes each comprise a plurality of first electrodes, with at least two of the first electrodes positioned at different heights on the piezoelectric layer. This IBAW resonator can achieve independent tuning of each mode of a multimodal resonator by providing an array of multiple interdigital electrodes of varying heights.

[0007] Optionally, the plurality of first electrodes have two different height values ​​on the piezoelectric layer.

[0008] Optionally, the plurality of first electrodes have three different height values ​​on the piezoelectric layer.

[0009] Optionally, the interdigital bulk acoustic wave resonator further includes a third interdigital electrode and a fourth interdigital electrode located between the piezoelectric layer and the substrate, each of the third interdigital electrode and the fourth interdigital electrode includes a plurality of second electrodes, and at least two of the second electrodes have different heights on the piezoelectric layer.

[0010] Optionally, the plurality of second electrodes are at two or three different heights on the piezoelectric layer.

[0011] Optionally, the heights of the first electrode and the second electrode on the piezoelectric layer are both between 1 nm and 1 μm.

[0012] Optionally, the material of the piezoelectric layer is one or more combinations of aluminum nitride, zinc oxide, lithium niobate, lithium tantalate, lead zirconate titanate piezoelectric ceramics, and barium sodium niobate.

[0013] Optionally, the piezoelectric stack includes at least two piezoelectric stacks, and heights of the multiple first electrodes of any one piezoelectric stack on the piezoelectric layer are different from heights of the multiple first electrodes of the remaining piezoelectric stacks on the piezoelectric layer.

[0014] Another aspect of the present invention provides a filter comprising a plurality of the above-mentioned interdigital BAW resonators, wherein M interdigital BAW resonators are connected in series to form a series branch, and N interdigital BAW resonators are connected in parallel to the series branch, where M and N are both positive integers.

[0015] Optionally, a height of the plurality of first electrodes of the IBDW resonators in the series branch on the piezoelectric layer is different from a height of the plurality of first electrodes of the IBDW resonators connected in parallel to the series branch on the piezoelectric layer.

[0016] The beneficial effects of the present invention include:

[0017] The interdigital bulk acoustic wave resonator provided in this embodiment includes a substrate and a piezoelectric stack located on the substrate, the piezoelectric stack including a piezoelectric layer located on the substrate and a first group of interdigital electrodes and a second group of interdigital electrodes located on the piezoelectric layer. A cavity is provided on a side of the substrate adjacent to the piezoelectric stack. The first group of interdigital electrodes and the second group of interdigital electrodes each include a plurality of first electrodes, and at least two of the first electrodes are at different heights on the piezoelectric layer. This application excites multimodal acoustic waves by distributing a first group of interdigital electrodes having a plurality of first electrodes and a second group of interdigital electrodes having a plurality of first electrodes on the surface of the piezoelectric layer, and setting the at least two first electrodes at different heights on the piezoelectric layer. This allows the impedance curve obtained by the interdigital bulk acoustic wave resonator provided in this application to have multiple main resonance peaks, thereby achieving independent tuning of each mode of the multimodal resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 One of the structural schematic diagrams of an interdigital bulk acoustic wave resonator provided in some embodiments of the present invention;

[0020] Figure 2 One of the schematic structural diagrams of the piezoelectric stack of the interdigital bulk acoustic wave resonator provided in some embodiments of the present invention;

[0021] Figure 3 A second schematic structural diagram of a piezoelectric stack of an interdigital bulk acoustic wave resonator provided in some embodiments of the present invention;

[0022] Figure 4 A third structural diagram of a piezoelectric stack of an interdigital bulk acoustic wave resonator provided in some embodiments of the present invention;

[0023] Figure 5 A fourth structural schematic diagram of a piezoelectric stack of an interdigital bulk acoustic wave resonator provided in some embodiments of the present invention;

[0024] Figure 6 A fifth structural diagram of a piezoelectric stack of an interdigital bulk acoustic wave resonator provided in some embodiments of the present invention;

[0025] Figure 7 A second structural schematic diagram of an interdigital bulk acoustic wave resonator provided in some embodiments of the present invention;

[0026] Figure 8A comparison diagram of impedance curves of interdigital bulk acoustic wave resonators provided by some embodiments of the present invention and existing resonators;

[0027] Figure 9 A schematic diagram of the structure of a filter provided in some embodiments of the present invention;

[0028] Figure 10 for Figure 9 The effect of the filter in ;

[0029] Figure 11 One of the impedance curve tuning comparison diagrams of the interdigital bulk acoustic wave resonator provided by some embodiments of the present invention;

[0030] Figure 12 This is a second comparison diagram of impedance curve tuning of the interdigital bulk acoustic wave resonator provided in some embodiments of the present invention.

[0031] Icon: 10 - substrate; 11 - cavity; 20 - piezoelectric stack; 21 - piezoelectric layer; 221 - first group of interdigital electrodes; 222 - second group of interdigital electrodes; 223 - first electrode; 231 - third interdigital electrode; 232 - fourth interdigital electrode; 233 - second electrode; a - first direction; b - second direction. DETAILED DESCRIPTION

[0032] The embodiments set forth below represent the information necessary to enable those skilled in the art to practice the embodiments and illustrate the best mode for practicing the embodiments. After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of the present invention and will recognize applications of these concepts not specifically set forth herein. It should be understood that these concepts and applications fall within the scope of the present invention and the appended claims.

[0033] It should be understood that although the terms first, second, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to regionally divide one element from another element. For example, without departing from the scope of the present invention, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0034] It should be understood that when an element (such as a layer, region or substrate) is referred to as being "on another element" or "extending onto another element", it may be directly on the other element or directly extending onto the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly on another element" or "extending directly onto another element", there are no intervening elements. Similarly, it should be understood that when an element (such as a layer, region or substrate) is referred to as being "above another element" or "extending over another element", it may be directly on the other element or directly extending over the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly on another element" or "extending directly over another element", there are no intervening elements. It should also be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0035] Relative terms, such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical", may be used herein to describe the relationship of one element, layer or region to another element, layer or region, as illustrated in the figures. It should be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0036] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms as well. It should also be understood that when used herein, the term "comprising" indicates the presence of the recited features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0037] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. It should also be understood that the terms used herein should be interpreted as having the same meaning as in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense, unless otherwise explicitly defined herein.

[0038] Please refer to Figure 1 and Figure 2This embodiment provides an interdigital BAW resonator (IBR) comprising a substrate 10 and a piezoelectric stack 20 located on substrate 10. The piezoelectric stack 20 comprises a piezoelectric layer 21 located on substrate 10, and a first set of interdigital electrodes 221 and a second set of interdigital electrodes 222 located on piezoelectric layer 21. A cavity 11 is provided on a side of substrate 10 adjacent to piezoelectric stack 20. Each of the first set of interdigital electrodes 221 and the second set of interdigital electrodes 222 comprises a plurality of first electrodes 223, with at least two first electrodes 223 having different heights on piezoelectric layer 21. This IBR can achieve independent tuning of each mode of a multi-mode resonator by providing multiple interdigital arrays of different heights.

[0039] The material of the substrate 10 is not limited in this application, and those skilled in the art can select a suitable material, such as silicon. The cavity 11 in the substrate 10 is formed by pre-filling a sacrificial material and then releasing the sacrificial material.

[0040] The piezoelectric stack 20 is disposed on the upper surface of the substrate 10 and includes a first set of interdigital electrodes 221 and a second set of interdigital electrodes 222. Figure 2 As shown, Figure 2 The figure shows a top view of the piezoelectric stack 20. In this embodiment, two groups of interdigital electrodes (i.e., a first group of interdigital electrodes 221 and a second group of interdigital electrodes 222) are arranged on the piezoelectric layer 21 in a metal electrode pattern similar to the interdigital fingers of two hands. It should be noted that in this embodiment, the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 have different polarities. For example, the first group of interdigital electrodes 221 can be positive electrodes, and the second group of interdigital electrodes 222 can be negative electrodes; alternatively, the first group of interdigital electrodes 221 can be negative electrodes, and the second group of interdigital electrodes 222 can be positive electrodes.

[0041] In this way, when an electrical signal is input to the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 in the interdigital bulk acoustic wave resonator to apply an electric field in the first direction a (wherein, the extension direction of the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 is the second direction b, the first direction a is parallel to the upper surface of the substrate 10, and the first direction a is perpendicular to the second direction b) to the piezoelectric layer 21, so that the piezoelectric layer 21 generates an electric field in the first direction a throughout its thickness direction (i.e., the direction perpendicular to the substrate 10), the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 can excite surface acoustic waves propagating along the first direction a in the piezoelectric layer 21.

[0042] Optionally, the material of the piezoelectric layer 21 may be any one or more combinations of aluminum nitride, zinc oxide, lithium niobate, lithium tantalate, lead zirconate titanate piezoelectric ceramics, and barium sodium niobate. The material of the first set of interdigital electrodes 221 and the second set of interdigital electrodes 222 may be any one or more combinations of molybdenum, platinum, gold, silver, aluminum, tungsten, titanium, ruthenium, copper, and chromium.

[0043] Please refer to Figure 1 and Figure 2 As shown, the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 each include a plurality of first electrodes 223. The first electrodes 223 of the first group of interdigital electrodes 221 and the first electrodes 223 of the second group of interdigital electrodes 222 are metal electrode patterns on the piezoelectric layer 21 that are similar to the fingers of two hands interlaced with each other.

[0044] In this embodiment, the heights of at least two first electrodes 223 on the piezoelectric layer 21 are different, including various forms. For example, the heights of at least two first electrodes 223 on the piezoelectric layer 21 may be different (e.g., Figure 4 As shown); for another example, at least two of the plurality of first electrodes 223 of the second group of interdigital electrodes 222 may have different heights on the piezoelectric layer 21 (not shown); for another example, at least one of the plurality of first electrodes 223 of the first group of interdigital electrodes 221 may have a different height on the piezoelectric layer 21 than at least one of the plurality of first electrodes 223 of the second group of interdigital electrodes 222 (as shown); Figure 3 shown).

[0045] Here, it should be noted that the height of the first electrode 223 on the piezoelectric layer 21 is the extension length of the first electrode 223 from the side of the piezoelectric layer 21 away from the substrate 10 toward the direction away from the substrate 10 .

[0046] In this embodiment, by setting the heights of at least two first electrodes 223 on the piezoelectric layer 21 to be different, multimodal acoustic waves can be generated. On the one hand, the number of filters in the RF front end of the communication system can be reduced, thereby meeting the requirements of high integration and miniaturization of RF devices. On the other hand, since the actual reflection interface of the sound wave in the interdigital bulk acoustic wave resonator is air, the thickness of the piezoelectric layer 21, the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 (i.e., the thickness of the piezoelectric layer 21, the height of the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 on the piezoelectric layer 21) will affect the resonant frequency. Therefore, the interdigital bulk acoustic wave resonator provided in the present application can excite the resonance peaks of the bulk acoustic wave resonator thickness mode with different resonant frequencies by at least two first electrodes 223 with different heights, thereby realizing independent tuning of each mode of the multimodal resonator.

[0047] It should be noted that if Figure 11 As shown, when there are only the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222, and when the multiple first electrodes 223 have two different height values ​​on the piezoelectric layer 21, the interdigital bulk acoustic wave resonator provided by the present application can have two resonance peaks with different resonant frequencies. By adjusting the height of the first electrode 223 on the piezoelectric layer 21, the purpose of tuning can be achieved. Taking the height value including the first height value H1 and the second height value H2 as an example, the second height value H2 can be kept unchanged, and the resonant frequency of the first resonance peak can be adjusted by independently adjusting the height of the first height value H1. Figure 11 The five resonant frequencies on the left are achieved by setting the first height value H1 to different heights. Figure 11 In the figure, the first height values ​​H1 corresponding to the five resonance peaks on the left from left to right are 0.3 μm, 0.29 μm, 0.28 μm, 0.27 μm and 0.26 μm respectively; the second height value H2 corresponding to the rightmost resonance peak (i.e. the second resonance peak) is 0.10 μm.

[0048] like Figure 12 As shown, the resonant frequency of the second resonance peak (ie, the left and right resonance peaks) can also be adjusted by independently adjusting the height value of the second height value H2. Figure 12 The five resonant frequencies on the right side are achieved by setting the second height value H2 to different heights. Figure 12, the first height values ​​H1 corresponding to the five resonance peaks on the right from left to right are 0.10μm, 0.09μm, 0.08μm, 0.07μm and 0.06μm respectively; the first height value H1 corresponding to the leftmost resonance peak (i.e., the first resonance peak) is 0.30μm. Of course, in addition to this method of adjusting the resonance frequency of the first resonance peak or the second resonance peak separately, in other embodiments, the resonance frequencies of the first resonance peak and the second resonance peak can also be adjusted simultaneously. Since the tuning method when the interdigital bulk acoustic wave resonator provided in this application has three or more resonance peaks is the same as the tuning method when it has two resonance peaks, those skilled in the art can simply deduce the tuning method based on the above-mentioned two resonance peaks. Therefore, it will not be repeated in this embodiment.

[0049] In summary, the interdigital bulk acoustic wave resonator provided in this embodiment includes a substrate 10 and a piezoelectric stack 20 located on the substrate 10. The piezoelectric stack 20 includes a piezoelectric layer 21 located on the substrate 10 and a first group of interdigital electrodes 221 and a second group of interdigital electrodes 222 located on the piezoelectric layer 21. A cavity 11 is provided on the side of the substrate 10 close to the piezoelectric stack 20; wherein the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 each include a plurality of first electrodes 223, and at least two of the first electrodes 223 have different heights on the piezoelectric layer 21. In the present application, a first group of interdigitated electrodes 221 having multiple first electrodes 223 and a second group of interdigitated electrodes 222 having multiple first electrodes 223 are distributed on the surface of the piezoelectric layer 21, and the heights of at least two first electrodes 223 on the piezoelectric layer 21 are set to different levels. In this way, multimodal acoustic waves can be excited, so that the impedance curve obtained by the interdigitated bulk acoustic wave resonator provided by the present application has multiple main resonance peaks, thereby realizing independent tuning of each mode of the multimodal resonator.

[0050] It should be noted that the interdigital bulk acoustic wave resonator provided in this application can be used to build duplexers, dual-passband filters, and multi-passband filters. Filters built using this resonator have adjustable dual or multi-passbands, meeting the market demands of modern wireless communications.

[0051] For example, in one possible embodiment, please refer to Figure 1 As shown, the plurality of first electrodes 223 have two different height values ​​on the piezoelectric layer 21. For ease of understanding, it is assumed that the two different height values ​​are a first height value and a second height value. The plurality of first electrodes 223 have two different height values ​​on the piezoelectric layer 21. In other words, it can be considered that the height of any first electrode 223 among all the first electrodes 223 is either the first height value or the second height value.

[0052] In this embodiment, the plurality of first electrodes 223 having two different height values ​​on the piezoelectric layer 21 also includes various situations. For example, the height of all first electrodes 223 of the first group of interdigital electrodes 221 may be a first height value, and the height of all first electrodes 223 of the second group of interdigital electrodes 222 may be a second height value (e.g., Figure 3 As described above); for another example, it may be that among all the first electrodes 223 of the first group of interdigital electrodes 221, the height of a portion of the first electrodes 223 is the first height value, and the height of another portion of the first electrodes 223 is the second height value. Among all the first electrodes 223 of the second group of interdigital electrodes 222, the height of a portion of the first electrodes 223 is the first height value, and the height of another portion of the first electrodes 223 is the second height value; for another example, it may be that all the first electrodes 223 of the first group of interdigital electrodes 221 include first electrodes 223 with the first height value and first electrodes 223 with the second height value, while the heights of all the first electrodes 223 of the second group of interdigital electrodes 222 are all the first height value or all the second height value; for another example, it may be that all the first electrodes 223 of the second group of interdigital electrodes 222 include first electrodes 223 with the first height value and first electrodes 223 with the second height value, while the heights of all the first electrodes 223 of the first group of interdigital electrodes 221 are all the first height value or all the second height value.

[0053] For example, in another feasible embodiment, the plurality of first electrodes 223 have three different height values ​​on the piezoelectric layer 21 .

[0054] Assume that the three different height values ​​are the first height value, the second height value, and the third height value. Then the multiple first electrodes 223 have three different height values ​​on the piezoelectric layer 21. In other words, it can be considered that the height of any one of the first electrodes 223 among all the first electrodes 223 is any one of the first height value, the second height value, and the third height value. In this embodiment, similar to the case where the multiple first electrodes 223 have two different height values ​​on the piezoelectric layer 21, when the multiple first electrodes 223 have three different height values ​​on the piezoelectric layer 21, it also includes multiple situations. Those skilled in the art can simply deduce each situation based on the relevant description of the multiple first electrodes 223 having two different height values ​​in the previous text, so this application will not go into details.

[0055] It should be understood that the aforementioned plurality of first electrodes 223 having two or three different height values ​​on the piezoelectric layer 21 is merely an example provided herein and should not be considered a limitation of the present application. For example, the plurality of first electrodes 223 may also have four or five different height values ​​on the piezoelectric layer 21, and such values ​​are not further enumerated herein. Furthermore, the height values ​​of all first electrodes 223 on the piezoelectric layer 21 may be different.

[0056] Please refer to Figure 5 and Figure 6 Optionally, the interdigital bulk acoustic wave resonator further includes a third interdigital electrode 231 and a fourth interdigital electrode 232 located between the piezoelectric layer 21 and the substrate 10, and the third interdigital electrode 231 and the fourth interdigital electrode 232 each include a plurality of second electrodes 233, and at least two second electrodes 233 have different heights on the piezoelectric layer 21.

[0057] The third interdigital electrode 231 and the fourth interdigital electrode 232 are respectively located on a side of the piezoelectric layer 21 close to the substrate 10. It should be noted that the height of the second electrode 233 on the piezoelectric layer 21 is the length of the second electrode 233 extending from the piezoelectric layer 21 toward the substrate 10.

[0058] It should be noted that the arrangement of the third interdigital electrodes 231 and the fourth interdigital electrodes 232 on the piezoelectric layer 21 is the same as the arrangement of the first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 on the piezoelectric layer 21. Figure 2 The first group of interdigital electrodes 221 and the second group of interdigital electrodes 222 are arranged on the piezoelectric layer 21 in the same manner.

[0059] The different heights of the at least two second electrodes 233 on the piezoelectric layer 21 also include multiple forms, and the forms included are the same as the forms included in the different heights of the at least two first electrodes 223 on the piezoelectric layer 21 mentioned above, so they will not be repeated in this application.

[0060] Similar to the first electrodes 223 on the voltage layer, in this embodiment, the plurality of second electrodes 233 may also be provided at two or three different heights on the piezoelectric layer 21. Specifically, the distribution of the two or three different heights of the second electrodes 233 is the same as described above and will not be further described in this application.

[0061] Optionally, the heights of the first electrode 223 and the second electrode 233 on the piezoelectric layer 21 are both between 1 nm and 1 μm. Specific heights of the first electrode 223 and the second electrode 233 can be selected by those skilled in the art within the above range, and this application does not impose any limitation thereto.

[0062] Please refer to Figure 7 As shown, optionally, the piezoelectric stack 20 includes at least two, and the height of the multiple first electrodes 223 of any one piezoelectric stack 20 on the piezoelectric layer 21 is different from the height of the multiple first electrodes 223 of the remaining piezoelectric stacks 20 on the piezoelectric layer 21.

[0063] Since the specific structure of the piezoelectric stack 20 has been described in detail above, it will not be repeated here. In this embodiment, the height of the multiple first electrodes 223 of any piezoelectric stack 20 on the piezoelectric layer 21 is different from the height of the multiple first electrodes 223 of the other piezoelectric stacks 20 on the piezoelectric layer 21. For ease of understanding, an example is given below. Assume that the piezoelectric stack 20 includes two, such as Figure 7 As shown, if the first electrode 223 included in the first piezoelectric stack 20 (the piezoelectric stack 20 on the left) has a first height value and a second height value, and the first electrode 223 included in the second piezoelectric stack 20 (the piezoelectric stack 20 on the right) has a third height value and a fourth height value, then the first height value and the second height value are neither equal to the third height value nor equal to the fourth height value.

[0064] Please refer to Figure 8 , Figure 8 This figure compares the impedance curves of the interdigital BAW resonator provided in this embodiment with those of existing resonators. The dashed line represents the impedance curve of the prior art resonator, while the solid line represents the impedance curve of the interdigital BAW resonator provided in this application. As can be seen from the figure, the interdigital BAW resonator provided in this application has a resonance peak at both 2.7 GHz and 3.6 GHz, with a distance of 900 MHz between the two peaks.

[0065] Furthermore, it should be noted that when the piezoelectric stack 20 includes at least two piezoelectric stacks, each piezoelectric stack 20 may include a third interdigital electrode 231 and a fourth interdigital electrode 232, or may not include the third interdigital electrode 231 and the fourth interdigital electrode 232. When the third interdigital electrode 231 and the fourth interdigital electrode 232 are included, the specific forms of the third interdigital electrode 231 and the fourth interdigital electrode 232 can be found in the previous description and will not be repeated here.

[0066] Please refer to Figure 9 As shown, another aspect of the present invention further provides a filter comprising a plurality of the aforementioned IBAW resonators, wherein M IBAW resonators are connected in series to form a series branch, and N IBAW resonators are connected in parallel to the series branch, where M and N are both positive integers. Since the specific structure and effective effects of the IBAW resonators have been described in detail above, they will not be repeated here.

[0067] For example, the filter can be Figure 9 The above-mentioned device comprises two interdigital BAW resonators connected in series and three interdigital BAW resonators connected in parallel. Of course, it should be understood that Figure 9 This is only an example, and those skilled in the art can choose the specific way to build the filter.

[0068] Please refer to Figure 10 , Figure 10 for the reason Figure 9 As shown in the figure, the filter constructed using the interdigital BAW resonator has two passbands: 2.4 GHz to 2.58 GHz and 3.56 to 3.9 GHz, which can meet the communication requirements of 2.4G, Wi-Fi, and 5G, n77 frequency bands respectively.

[0069] Optionally, the height of the multiple first electrodes 223 of the IBDW resonators in the series branch on the piezoelectric layer 21 is different from the height of the multiple first electrodes 223 of the IBDW resonators connected in parallel to the series branch on the piezoelectric layer 21 .

[0070] For ease of understanding, use Figure 9 The filter shown is used as an example. The two interdigital BAW resonators connected in series are assumed to be divided into a first resonator (assuming that the height values ​​of the multiple first electrodes 223 of the resonator on the piezoelectric layer 21 include a first height value and a second height value) and a second resonator (assuming that the height values ​​of the multiple first electrodes 223 of the resonator on the piezoelectric layer 21 include a third height value and a fourth height value), and the three interdigital BAW resonators connected in parallel are assumed to be divided into a third resonator (assuming that the height values ​​of the multiple first electrodes 223 of the resonator on the piezoelectric layer 21 include a fifth height value and a sixth height value), a fourth resonator (assuming that the height values ​​of the multiple first electrodes 223 of the resonator on the piezoelectric layer 21 include a seventh height value and an eighth height value), and a fifth resonator (assuming that the height values ​​of the multiple first electrodes 223 of the resonator on the piezoelectric layer 21 include a ninth height value and a tenth height value). Then each of the four height values ​​(the first height value, the second height value, the third height value and the fourth height value) is not equal to any one of the six height values ​​(the fifth height value, the sixth height value, the seventh height value, the eighth height value, the ninth height value and the tenth height value).

[0071] The foregoing description is merely an optional embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

[0072] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. An interdigital bulk acoustic wave resonator, characterized in that: The piezoelectric stack comprises a substrate and a piezoelectric stack located on the substrate, the piezoelectric stack comprising a piezoelectric layer located on the substrate and a first group of interdigital electrodes and a second group of interdigital electrodes located on the piezoelectric layer, wherein a cavity is provided on a side of the substrate adjacent to the piezoelectric stack; wherein each of the first group of interdigital electrodes and the second group of interdigital electrodes comprises a plurality of first electrodes, and at least two of the first electrodes have different heights on the piezoelectric layer, and the plurality of first electrodes have two or three different height values ​​on the piezoelectric layer; The interdigital bulk acoustic wave resonator further includes a third interdigital electrode and a fourth interdigital electrode located between the piezoelectric layer and the substrate, wherein the third interdigital electrode and the fourth interdigital electrode each include a plurality of second electrodes, and at least two of the second electrodes have different heights on the piezoelectric layer, and the plurality of second electrodes have two or three different heights on the piezoelectric layer; The piezoelectric stacks include at least two, and the heights of the plurality of first electrodes of any one of the piezoelectric stacks on the piezoelectric layer are different from the heights of the plurality of first electrodes of the remaining piezoelectric stacks on the piezoelectric layer; The heights of the first electrode and the second electrode on the piezoelectric layer are both between 1 nm and 1 μm. Different heights of the first electrode and different heights of the second electrode correspond to different resonant frequencies. By adjusting the heights of the first electrode and the second electrode, the impedance curve of the interdigital bulk acoustic wave resonator has multiple main resonant peaks, and the frequency interval between the multiple main resonant peaks is greater than or equal to 900 MHz.

2. The interdigital bulk acoustic wave resonator according to claim 1, wherein: The material of the piezoelectric layer is one or more combinations of aluminum nitride, zinc oxide, lithium niobate, lithium tantalate, lead zirconate titanate piezoelectric ceramics, and barium sodium niobate.

3. A filter, characterized in that: The method comprises a plurality of interdigital BAW resonators according to any one of claims 1 to 2, wherein M of the interdigital BAW resonators are connected in series to form a series branch, and N of the interdigital BAW resonators are connected in parallel to the series branch, and M and N are positive integers respectively.

4. The filter according to claim 3, characterized in that The height of the plurality of first electrodes of the IBDW resonator in the series branch on the piezoelectric layer is different from the height of the plurality of first electrodes of the IBDW resonator connected in parallel to the series branch on the piezoelectric layer.

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