Filter integrating fundamental wave resonator and harmonic wave resonator and manufacturing method thereof

Abstract

The invention relates to a filter integrating a fundamental wave resonator and a harmonic wave resonator and a manufacturing method of the filter, the fundamental wave resonator and the harmonic wave resonator are resonators in a thickness extension vibration mode, the fundamental wave resonator and the harmonic wave resonator are integrated on a single chip in a single crystal mode, the stack acoustic phase length hph of the fundamental wave resonator and the harmonic wave resonator is close to pi n, n is a harmonic order, and the acoustic phase lengths of the dielectric layers of the fundamental wave resonator and the harmonic wave resonator approach to pi (n-1). Dielectric layers with different thicknesses are arranged in a fundamental wave resonator area and a harmonic wave resonator area, the acoustic phase length of the dielectric layers of the fundamental wave resonator and the harmonic wave resonator is pi (n-1), the fundamental wave resonator and the harmonic wave resonator are integrated on a single chip, and therefore a wider frequency range and more suitable electromechanical coupling are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of resonators, and particularly to a filter integrating a fundamental wave resonator and a harmonic resonator, and a manufacturing method of a filter integrating a fundamental wave resonator and a harmonic resonator. Background Art

[0002] RF components such as resonators and filters based on microelectromechanical system (MEMS) technology are widely used in telecommunication fields such as mobile phones, wireless networks, and positioning systems. These components have key advantages such as small size, good scalability, and convenience for large-scale production. The new generation of communication standards requires higher data rates, which necessarily requires the filter passband to have a wider bandwidth and the stopband to have a higher suppression level. In acoustic technology, bulk acoustic wave (BAW) technology is expected to dominate in next-generation applications because they can meet the requirements of high-frequency operation, broadband functionality, low loss, and strict power requirements.

[0003] Compared with the thickness shear (TS) vibration mode, the thickness extensional (TE) vibration mode has significant advantages. For example, a thin film of a specific material (AlN and / or Al 1-x Sc x N) in the TE vibration mode has higher electromechanical coupling, which means a wider bandwidth and more efficient energy conversion. In addition, the TE vibration mode is more capable of achieving high frequencies, which is crucial for meeting the requirements of advanced communication systems. In contrast, the TS vibration mode usually exhibits lower electromechanical coupling and acoustic phase velocity, making them less efficient for applications that require wide bandwidth and high-frequency operation. In addition, the AlN thin film deposition technology optimized for the TE vibration mode is more mature than the thin film integration technology optimized for the TS vibration mode.

[0004] The fundamental wave resonator in the thickness extensional vibration mode can provide high electromechanical coupling, but its frequency range is limited. Summary of the Invention

[0005] Based on this, it is necessary to provide a filter integrating a fundamental wave resonator and a harmonic resonator and its manufacturing method to take into account a wider frequency range and more appropriate electromechanical coupling.

[0006] A filter integrating a fundamental resonator and a harmonic resonator, characterized in that the fundamental resonator and the harmonic resonator are resonators in a thickness-extensional vibration mode, and the harmonic order of the harmonic resonator is not less than 2. The fundamental resonator and the harmonic resonator are monocrystalline integrated on a single chip. The filter includes a mirror, a bottom electrode layer, a piezoelectric layer, a top electrode layer, a dielectric layer, and a passivation layer stacked in sequence. The stack acoustic phase length h of the fundamental resonator and the harmonic resonator ph approaches πn, where n is the harmonic order. The stack acoustic phase length h ph is the sum of the acoustic phase lengths of the bottom electrode layer, the piezoelectric layer, the top electrode layer, the dielectric layer, and the passivation layer of the resonator. The acoustic phase length of the dielectric layer of the fundamental resonator and the harmonic resonator approaches π(n - 1). The thickness of the dielectric layer of the harmonic resonator is greater than the thickness of the dielectric layer of the fundamental resonator.

[0007] For the above filter integrating a fundamental resonator and a harmonic resonator, by setting dielectric layers with different thicknesses in the fundamental resonator region and the harmonic resonator region, the acoustic phase lengths of the dielectric layers of the fundamental resonator and the harmonic resonator are π(n - 1), and the fundamental resonator and the harmonic resonator are integrated onto a single chip (Die), thereby achieving a wider frequency range and more appropriate electromechanical coupling.

[0008] In one embodiment, the fundamental resonator serves as a parallel resonator in the filter, and the harmonic resonator serves as a series resonator in the filter.

[0009] In one embodiment, the filter is a bulk acoustic wave filter.

[0010] In one embodiment, the dielectric layer is used for frequency tuning and frequency temperature coefficient compensation.

[0011] In one embodiment, the fundamental resonator and the harmonic resonator are fixed resonators.

[0012] In one embodiment, the fundamental resonator and the harmonic resonator are thin film bulk acoustic wave resonators.

[0013] In one embodiment, the mirror, the bottom electrode layer, the piezoelectric layer, and the top electrode layer of the fundamental resonator and the harmonic resonator have the same thickness.

[0014] In one embodiment, the filter integrating a fundamental resonator and a harmonic resonator further includes a seed layer located on the mirror and under the bottom electrode layer and the piezoelectric layer. The material of the seed layer includes aluminum nitride.

[0015] In one embodiment, the harmonic resonator includes at least two resonators with different harmonic orders.

[0016] In one embodiment, the material of the piezoelectric layer includes scandium-doped aluminum nitride.

[0017] A method for manufacturing a filter integrating a fundamental resonator and a harmonic resonator, where the fundamental resonator and the harmonic resonator are resonators in thickness-extensional vibration mode, and the harmonic order of the harmonic resonator is not less than 2. The method includes: obtaining a wafer formed with a mirror, a bottom electrode layer, a piezoelectric layer, and a top electrode layer stacked in sequence; forming dielectric layers with different thicknesses in regions of the wafer for forming different resonators; the acoustic phase lengths of the dielectric layers of the fundamental resonator and the harmonic resonator approach π(n - 1), where n is the harmonic order of the resonator in thickness-extensional vibration mode; forming a passivation layer covering the dielectric layers; the stack acoustic phase length h ph approaches πn, and the stack acoustic phase length h ph is the sum of the acoustic phase lengths of the bottom electrode layer, the piezoelectric layer, the top electrode layer, the dielectric layer, and the passivation layer of the resonator; wherein, the fundamental resonator and the harmonic resonator are included on a single chip of the wafer.

[0018] The above method for manufacturing a filter integrating a fundamental resonator and a harmonic resonator forms dielectric layers with different thicknesses in the fundamental resonator region and the harmonic resonator region, so that the acoustic phase lengths of the dielectric layers of the fundamental resonator and the harmonic resonator are π(n - 1), integrating the fundamental resonator and the harmonic resonator onto a single chip, thereby achieving a wider frequency range and more suitable electromechanical coupling.

[0019] In one embodiment, before the step of obtaining a wafer formed with a mirror, a bottom electrode layer, a piezoelectric layer, and a top electrode layer stacked in sequence, it further includes: determining the structural parameters of the mirror according to the frequency range of the passband of the filter to achieve frequency screening of sound waves; adjusting the structural parameters of the bottom electrode layer, the piezoelectric layer, the top electrode layer, the dielectric layer, and the passivation layer through simulation to balance the electromechanical coupling and frequency characteristics of the fundamental resonator and the harmonic resonator; further adjusting the structural parameters of each film layer of the filter through simulation to optimize the resonator performance and meet the design specifications.

[0020] In one embodiment, in the step of obtaining a wafer formed with a mirror, a bottom electrode layer, a piezoelectric layer, and a top electrode layer stacked in sequence, the thicknesses of the mirror, the bottom electrode layer, the piezoelectric layer, and the top electrode layer in the regions for forming different resonators are the same.

[0021] In one embodiment, after forming the passivation layer, it further includes a step of cutting the wafer into individual chips by dicing, and a single chip includes the fundamental resonator and the harmonic resonator. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 It is a schematic structural diagram of a filter integrating a fundamental resonator and a harmonic resonator in an embodiment of the present application.

[0024] Figure 2a It is the circuit topology of a ladder filter in an embodiment of the present application, Figure 2b It is adopted in an embodiment of the present application Figure 2a The broadband filter response of the circuit topology shown. Figure 2c It is in an embodiment of the present application Figure 2a The narrowband filter response with a superimposed resonator response of the circuit topology shown.

[0025] Figure 3 It is a schematic diagram showing the variation of the transmittance of a Bragg acoustic mirror with frequency.

[0026] Figure 4 It is a flowchart of a method for manufacturing a filter integrating a fundamental resonator and a harmonic resonator in an embodiment of the present application.

[0027] Figure 5 It is a flowchart of sub-steps before step S110 in an embodiment of the present application.

[0028] Figure 6 It is a curve graph of the electromechanical coupling varying with the acoustic phase length h of the dielectric layer pht of the dielectric layer.

[0029] Figure 7 It is a curve graph of the relationship between the electromechanical coupling and frequency of the TE1 and TE2 resonators when the thickness of the dielectric layer changes.

[0030] Figure 8a It is the admittance response curve of TE1 when the thickness of the dielectric layer is 110nm, 65nm, and 5nm respectively, Figure 8b It is the admittance response curve of TE2 when the thickness of the dielectric layer is 560nm, 480nm, and 400nm respectively. Detailed Embodiments

[0031] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present application is more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0033] It should be understood that when an element or layer is referred to as "on", "adjacent to", "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as "directly on", "directly adjacent to", "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although terms such as first, second, third, etc. may be used to describe various elements, components, regions, layers, doping types and / or parts, these elements, components, regions, layers, doping types and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type or part from another element, component, region, layer, doping type or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer, doping type or part discussed below may be referred to as the second element, component, region, layer or part; for example, the first doping type may be referred to as the second doping type, and similarly, the second doping type may be referred to as the first doping type; the first doping type and the second doping type are different doping types. For example, the first doping type may be P-type and the second doping type may be N-type, or the first doping type may be N-type and the second doping type may be P-type.

[0034] Spatial relationship terms such as "under", "below", "beneath", "underneath", "above", "over", etc. may be used herein to describe the relationship of one 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, spatial relationship terms also include different orientations of the device in use and operation. For example, if the device in the attached figures is flipped, an element or feature described as "under other elements" or "beneath them" or "underneath them" will be oriented "over" the other elements or features. Thus, the exemplary terms "under" and "underneath" can include both an upper and a lower orientation. In addition, the device may also include additional orientations (such as, rotated 90 degrees or other orientations), and the spatial descriptors used herein are to be interpreted accordingly.

[0035] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprises / comprising" or "has / having" etc. specify the presence of the stated features, integers, steps, operations, components, parts or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts or combinations thereof. At the same time, in this specification, the term "and / or" includes any and all combinations of the related listed items.

[0036] Embodiments of the invention are described herein with reference to cross-sectional views that are schematic illustrations of ideal embodiments (and intermediate structures) of the invention, such that variations in the illustrated shapes due to, for example, manufacturing techniques and / or tolerances are to be expected. Accordingly, embodiments of the invention should not be limited to the particular shapes of regions shown herein, but include shape deviations due to, for example, manufacturing techniques. For example, an implantation region shown as rectangular will typically have rounded or curved features at its edges and / or an implantation concentration gradient, rather than a binary change from the implanted region to the non-implanted region. Similarly, a buried region formed by implantation can result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions shown in the figures are substantially schematic, and their shapes do not represent the actual shapes of regions of the device and do not limit the scope of the invention.

[0037] The present application introduces a platform that overcomes the limitations of traditional TE1-mode BAW (bulk acoustic wave) filter designs by integrating resonators operating in the fundamental thickness extensional mode (i.e., thickness extensional first order, TE1, with a harmonic order of 1) and harmonic thickness extensional modes (which can be TE2, TE3, etc.) onto a single acoustic chip (Die). By allowing adjustment of the thickness of the dielectric layer on the top electrode layer in the resonator stack, this platform enables seamless mode conversion, thereby achieving a wider frequency range and more suitable electromechanical coupling. The fundamental mode uses a thin resonator cavity, while the harmonic mode uses a thicker resonator cavity. This approach provides a flexible platform for designing BAW filters suitable for various applications.

[0038] Figure 1 FIG. 4 is a schematic structural diagram of a filter integrating a fundamental resonator and a harmonic resonator in an embodiment of the present application. The fundamental resonator and the harmonic resonator are resonators in a thickness extension vibration mode, and the harmonic order of the harmonic resonator is not less than 2 (i.e., it can be second-order TE2, third-order TE3, fourth-order TE4, etc.). The fundamental resonator and the harmonic resonator are monocrystalline integrated on a single chip. The filter includes a mirror 120, a bottom electrode layer 130, a piezoelectric layer 140, a top electrode layer 150, a dielectric layer 160, and a passivation layer 170 stacked in sequence. The stacked acoustic phase length h of the fundamental resonator and the harmonic resonator ph approaches (is approximately equal to) πn, where n is the harmonic order of the resonator in the thickness extension vibration mode, and h ph is the sum of the acoustic phase lengths of the bottom electrode layer, the piezoelectric layer, the top electrode layer, the dielectric layer, and the passivation layer of the resonator. The acoustic phase length h of the dielectric layer of the fundamental resonator and the harmonic resonator pht approaches (is approximately equal to) π(n - 1). Therefore, the total thickness of the stack of each resonator (the sum of the thicknesses of the bottom electrode layer 130, the piezoelectric layer 140, the top electrode layer 150, the dielectric layer 160, and the passivation layer 170) is approximately equal to a multiple (n times) of half the wavelength of each resonator. h ph approaches πn, and h pht approaches π(n - 1), which means that the inventor believes that when h ph = πn and h pht = π, the resonator theoretically has the best electromechanical coupling performance. However, in actual production, due to process errors and other reasons, the acoustic phase length (corresponding thickness) of the film layer can also deviate slightly from the theoretical value.

[0039] The thickness of the dielectric layer 160 of the harmonic resonator is greater than that of the fundamental resonator. In Figure 1 the illustrated embodiment, the fundamental resonator is a TE2 resonator, i.e., n = 2, h ph ≈ 2π, h pht ≈ π.

[0040] For the above filter integrating the fundamental resonator and the harmonic resonator, by setting dielectric layers 160 with different thicknesses in the fundamental resonator region and the harmonic resonator region, the acoustic phase lengths of the dielectric layers of the fundamental resonator and the harmonic resonator are π(n - 1), and the fundamental resonator and the harmonic resonator are integrated onto a single chip, thereby achieving a wider frequency range and more appropriate electromechanical coupling.

[0041] Referring to Figure 2a , in an embodiment of the present application, the fundamental resonator and the harmonic resonator form a ladder filter, the fundamental resonator serves as a shunt resonator in the ladder filter, and the harmonic resonator serves as a series resonator in the ladder filter. Figure 2b is the broadband filter response adopting the Figure 2a illustrated circuit topology in an embodiment of the present application, Figure 2c is the narrowband filter response with a superimposed resonator response of the Figure 2a illustrated circuit topology in an embodiment of the present application. For Figure 2c each curve in, the solid line is the forward transmission S parameter, and the dashed line is the admittance of the resonator constituting the filter.

[0042] In another embodiment of the present application, it may also be that the fundamental resonator serves as a series resonator in the ladder filter and the harmonic resonator serves as a shunt resonator in the ladder filter. In other embodiments of the present application, other filter orders and topologies are also possible.

[0043] In an embodiment of the present application, the dielectric layer 160 is used for frequency tuning and temperature coefficient of frequency (TCF) compensation. The material of the dielectric layer 160 may be silicon dioxide.

[0044] In an embodiment of the present application, the fundamental resonator and the harmonic resonator are solidly mounted resonators (SMRs). Further, the mirror 120 may be a Bragg acoustic mirror, and the mirror 120 includes a low acoustic impedance layer 122 and a high acoustic impedance layer 124. In Figure 1In the illustrated embodiment, the low acoustic impedance layer 122 and the high acoustic impedance layer 124 are not patterned; in other embodiments of the present application, the Bragg acoustic mirror may also have a patterned high acoustic impedance layer 124 and / or low acoustic impedance layer 122. Among them, the low acoustic impedance material of the low acoustic impedance layer 122 may be at least one of silicon dioxide, aluminum, benzocyclobutene (BCB), polyimide, and spin on glass, and the high acoustic impedance material of the high acoustic impedance layer 124 may be at least one of molybdenum, tungsten, titanium, platinum, aluminum nitride, aluminum oxide, tungsten oxide, and silicon nitride; it can be understood that in other embodiments, other material combinations with a large impedance ratio may also be used for the low acoustic impedance material and the high acoustic impedance material.

[0045] Figure 3 is a schematic diagram showing the transmittance of the Bragg acoustic mirror varying with frequency. The acoustic Bragg mirror is composed of three pairs of alternating SiO2 layers (low acoustic impedance layer 122) and AlN layers (high acoustic impedance layer 124), and the acoustic Bragg mirror is formed on a silicon (Si) substrate. An additional top SiO2 layer is added to the mirror. The thicknesses of these layers are: the bottom three SiO2 layers are 260 nm, the bottom three AlN layers are 480 nm, and the topmost SiO2 layer is 280 nm.

[0046] In one embodiment of the present application, the fundamental wave resonator and the harmonic wave resonator are film bulk acoustic wave resonators (FBARs), and an air cavity formed below the bottom electrode layer is used as a mirror.

[0047] In one embodiment of the present application, the mirrors 120, the bottom electrode layer 130, the piezoelectric layer 140, and the top electrode layer 150 of the fundamental wave resonator and the harmonic wave resonator have the same thickness, and different stack acoustic phase lengths h are obtained by setting dielectric layers 160 with different thicknesses for resonators of different harmonic orders. ph 。

[0048] In one embodiment of the present application, the harmonic resonator includes at least two resonators with different harmonic orders, for example, a resonator of TE2 and a resonator of TE3.

[0049] In one embodiment of the present application, the mirror 120 is disposed on the substrate 110, and the substrate 110 may be a silicon substrate. Further, the substrate 110 may be a single-crystalline silicon substrate with a <111> crystal orientation.

[0050] In one embodiment of the present application, the filter further includes a seed layer 132 located on the mirror 120 and under the bottom electrode layer 130 and the piezoelectric layer 140. The material of the seed layer 132 includes aluminum nitride. The seed layer 132 is used to promote the growth of the film layer above it.

[0051] In one embodiment of the present application, a diffusion barrier layer is provided on the upper surface of the top electrode layer 150, and the material of the diffusion barrier layer is Ti.

[0052] In one embodiment of the present application, the filter further includes a Ti frame layer 152 located on the top electrode layer 150, and the top electrode layer 150 and the Ti frame layer 152 are covered by a passivation layer 170.

[0053] In one embodiment of the present application, the material of the piezoelectric layer 140 is scandium-doped aluminum nitride. In one embodiment of the present application, the material of the bottom electrode layer 130 is Mo. In one embodiment of the present application, the material of the top electrode layer 150 is Al.

[0054] In one embodiment of the present application, the filter is a filter covering UNII bands 1, 2, and 3, that is, a filter centered at 5502.5 MHz with a bandwidth of 665 MHz.

[0055] The present application correspondingly provides a method for manufacturing a filter integrating a fundamental resonator and a harmonic resonator, which can be used to manufacture the filter integrating a fundamental resonator and a harmonic resonator described in any of the above embodiments. Figure 4 is a flowchart of a method for manufacturing a filter integrating a fundamental resonator and a harmonic resonator in an embodiment of the present application, including the following steps:

[0056] S110, obtain a wafer formed with a mirror, a bottom electrode layer, a piezoelectric layer, and a top electrode layer stacked in sequence.

[0057] In one embodiment of the present application, the mirror 120, the bottom electrode layer 130, the piezoelectric layer 140, and the top electrode layer 150 are formed in sequence from bottom to top. Other film layers may also be formed between these film layers. In one embodiment of the present application, the mirror 120 is formed on the substrate 110. In one embodiment of the present application, after forming the mirror 120, it further includes the step of forming a seed layer 132 on the mirror 120. The bottom electrode layer 130 and the piezoelectric layer 140 are formed on the seed layer 132.

[0058] S120, form dielectric layers with different thicknesses in the regions of different resonators on the wafer.

[0059] The acoustic phase length h of the dielectric layer of the fundamental resonator and the harmonic resonator phtApproaches (i.e., is approximately equal to) π(n - 1), where n is the harmonic order of the resonator in the thickness-extensional vibration mode.

[0060] S130, to form a passivation layer covering the dielectric layer.

[0061] The stack acoustic phase length h of the resonator ph Approaches (is approximately equal to) πn, where n is the harmonic order of the resonator in the thickness-extensional vibration mode. The stack acoustic phase length h ph Is the sum of the acoustic phase lengths of the bottom electrode layer, piezoelectric layer, top electrode layer, dielectric layer, and passivation layer of the resonator. The total thickness of the stack (the sum of the thicknesses of the bottom electrode layer 130, piezoelectric layer 140, top electrode layer 150, dielectric layer 160, and passivation layer 170) is approximately equal to n times the half-wavelength of each resonator.

[0062] In an embodiment of the present application, after step S130, it further includes a step of dicing the wafer into individual chips (Dies) through scribing. A single chip includes a fundamental resonator and a harmonic resonator.

[0063] The manufacturing method of the structure of the filter integrating the fundamental resonator and the harmonic resonator, by forming dielectric layers with different thicknesses in the fundamental resonator region and the harmonic resonator region, such that the acoustic phase lengths of the dielectric layers of the fundamental resonator and the harmonic resonator are π(n - 1), integrating the fundamental resonator and the harmonic resonator onto a single chip, thereby achieving a wider frequency range and more suitable electromechanical coupling. By precisely setting the thickness of the dielectric layer 160, different resonators can be formed in the same material stack, and each resonator is customized to achieve different resonant frequencies and coupling characteristics. This innovative method simplifies the manufacturing process, reduces complexity and related costs, while achieving a higher level of customization and optimization of key performance indicators.

[0064] In an embodiment of the present application, before step S120, it further includes a step of forming a diffusion barrier layer on the upper surface of the top electrode layer 150, and the material of the diffusion barrier layer is Ti.

[0065] In an embodiment of the present application, it further includes a step of forming a Ti frame layer 152 on the top electrode layer 150.

[0066] See Figure 5 , in an embodiment of the present application, before step S110, it further includes a step of performing a structural design on the filter, specifically including:

[0067] S102, to determine the structural parameters of the mirror according to the frequency range of the passband of the filter.

[0068] Determine the structural parameters of the mirror 120 according to the frequency range of the passband of the filter to achieve frequency screening of sound waves. Create a mirror 120 with optimal reflectivity characteristics for the defined passband, ensuring effective energy limitation when necessary and allowing energy to pass through when not needed.

[0069] S104, adjust the structural parameters of the stack to balance the electromechanical coupling and frequency characteristics of the fundamental wave and harmonic resonators.

[0070] Through simulation, adjust and optimize the structural parameters (including shape, pattern, size, etc.) of the stack (including the bottom electrode layer 130, piezoelectric layer 140, top electrode layer 150, dielectric layer 160, and passivation layer 170) above the mirror 120 to balance the electromechanical coupling and frequency characteristics of the fundamental wave mode (corresponding to the fundamental wave resonator) and harmonic wave mode (corresponding to the harmonic resonator). These resonators operating in different modes share the same film layers in the chip. The thicknesses of different film layers can be finely adjusted, and only the thickness of the dielectric layer 160 can be significantly changed to achieve the transition between modes.

[0071] For the acoustic phase length h of the stack ph , , where h is the thickness of the film layer, v ph is the phase velocity of the wave, and f is the operating frequency. Figure 6 Shows how the electromechanical coupling varies with the acoustic phase length h of the dielectric layer pht formed in the resonator of the embodiment corresponding to the curve, and the specific film layer structure is as follows: the material of the seed layer 132 is AlN, and the thickness is 30 nm; the material of the bottom electrode layer 130 is Mo, and the thickness is 90 nm; the material of the piezoelectric layer 140 is Al Figure 3 Sc 80% Sc 20% N, the thickness is 480 nm, the material of the top electrode layer 150 is Al, and the thickness is 90 nm; the material of the diffusion barrier layer is Ti, and the thickness is 10 nm. The thickness of the dielectric layer 160 varies from 5 nm to 650 nm. It should be noted that the h corresponding to the maximum coupling of the TE2 resonator pht is smaller than π because the electrodes and the passivation layer 170 have contributed to the acoustic phase length of the top stack above the piezoelectric layer 140. Figure 6 In, the solid line is the curve corresponding to the TE1 resonator, and the dashed line is the curve corresponding to the TE2 resonator.

[0072] Figure 7 Shows when Figure 3 and Figure 6 the thickness of the dielectric layer 160 described changes, the relationship between the electromechanical coupling and frequency of the TE1 (solid line) and TE2 (dashed line) resonators, Figure 7In the illustrated embodiment, the dielectric layer 160 is a SiO2 layer. The curves of the TE1 resonator correspond to the thickness of the dielectric layer 160 varying from 5 nm to 190 nm, and the curves of the TE2 resonator correspond to the thickness of the dielectric layer 160 varying from 350 nm to 630 nm.

[0073] Figure 8a The admittance response curves of TE1 are shown for the thicknesses of the dielectric layer 160 being 110 nm, 65 nm, and 5 nm (from low frequency to high frequency); Figure 8b The admittance response curves of TE2 are shown for the thicknesses of the dielectric layer 160 being 560 nm, 480 nm, and 400 nm (from low frequency to high frequency).

[0074] S106. Further adjust the structural parameters of the stack to optimize the resonator performance and meet the design specifications.

[0075] Modify the structural parameters of each film layer of the filter as needed to further optimize the filter performance and meet specific design specifications. For example, the loss can be reduced by adjusting the dispersion curve behavior of the stack, the mirror 120 can be adjusted to reflect shear wave components other than the longitudinal wave component, or spurious modes can be suppressed, as well as other improvements.

[0076] After step S106 is completed, according to the structural parameters of each film layer of the filter obtained by adjustment, execute steps S110 to S130 to manufacture the filter.

[0077] Based on all of the above embodiments, the filter integrating the fundamental mode resonator and the harmonic mode resonator of the embodiments of the present application has the following advantages:

[0078] Increased frequency range: By combining the fundamental mode resonator and the harmonic mode resonator, the frequency range of high electromechanical coupling is expanded, thereby allowing a larger bandwidth of resonant frequencies.

[0079] Increased electromechanical coupling range: The filter can provide a wider range of electromechanical coupling values, including those of the fundamental mode and the harmonic mode, thus providing greater flexibility for filter design.

[0080] Good thermal stability: The harmonic mode resonator exhibits very good thermal stability due to the thick SiO2 material TCF compensation layer (dielectric layer 160).

[0081] Enhanced design flexibility: The combination of the above points enables the achievement of a wide range of frequency and performance characteristics, making it applicable to filter design.

[0082] Single-chip solution: All resonators are fabricated on a single chip with shared material layers, which greatly reduces the manufacturing complexity and cost compared to a multi-chip solution.

[0083] Cost reduction: Minimize the need for complex multi-chip processing, simplify the manufacturing process and reduce its cost.

[0084] Embodiments of this application provide a method and platform for designing and manufacturing radio frequency (RF) or bulk acoustic wave (BAW) filters by integrating resonators of multiple harmonic orders within a single chip. All resonators are fabricated through the same wafer-level process and are differentiated by applying specific trimming or etching steps (as well as layout variations such as size and shape) to shared layers.

[0085] By adjusting the resonator cavity size, a wide frequency range and diverse electromechanical couplings can be achieved, enabling the resonators to operate in different bulk acoustic wave vibration modes. For example, resonators with thinner cavities (mainly defined by the piezoelectric layer) support the thickness-extensional fundamental mode (TE1), while resonators with thicker cavities support thickness-extensional harmonic modes (TE2, TE3, etc.). The thickness-extensional harmonic modes are mainly defined by the piezoelectric layer 140 and the dielectric layer 160, and the dielectric layer 160 is also typically used to stabilize the resonator performance against temperature variations.

[0086] In each TEn vibration mode, the thickness of the piezoelectric layer 140 is set to be close to half of the wavelength corresponding to the designed center frequency to maximize the electromechanical coupling coefficient. The TE1 vibration mode consists only of the film layer corresponding to this half-wavelength, while the harmonic vibration modes include additional half-wavelength portions (extending to the film layer from the top electrode layer 150 to the passivation layer 170) to complete their respective harmonic orders.

[0087] Although parameters such as frequency, electromechanical coupling, capacitance, and temperature coefficient of frequency (TCF) can be modified by adjusting each film layer, the main advantage of this platform lies in its ability to adjust the frequency and coupling characteristics of the resonator by changing the thickness of the dielectric layer 160 located above the top electrode layer 150. The dielectric layer 160 is typically used to improve the TCF and achieve a smooth transition between different resonators, thus supporting a seamless transition between the fundamental and harmonic vibration modes. This provides higher flexibility for resonator design and overall performance. At the same time, this application also provides a solution for integrating resonators with a wider frequency range to achieve wideband and large-bandwidth filters on a single chip.

[0088] The manufacturing method of the filter integrating fundamental and harmonic resonators of this application is based on the same inventive concept as the filter integrating fundamental and harmonic resonators. For details not specifically described in the manufacturing method of the filter integrating fundamental and harmonic resonators, reference can be made to the introduction of the filter integrating fundamental and harmonic resonators above.

[0089] It should be understood that although the steps in the flowcharts of the present application are shown in sequence according to the indications of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise clearly stated herein, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in the flowcharts of the present application may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least some of the steps or stages in other steps or other steps.

[0090] In the description of this specification, the descriptions referring to terms such as "some embodiments", "other embodiments", "ideal embodiments", etc. mean that the specific features, structures, materials or features described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0091] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features of the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0092] The above-described embodiments only represent several implementation manners of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A filter integrating a fundamental resonator and a harmonic resonator, characterized in that, The fundamental resonator and the harmonic resonator are resonators in a thickness-extensional vibration mode, and the harmonic order of the harmonic resonator is not less than 2. The fundamental resonator and the harmonic resonator are monocrystalline integrated on a single chip. The filter includes a mirror, a bottom electrode layer, a piezoelectric layer, a top electrode layer, a dielectric layer, and a passivation layer stacked in sequence. The stack acoustic phase length h of the fundamental resonator and the harmonic resonator ph approaches π×n, where n is the harmonic order. The stack acoustic phase length h ph is the sum of the acoustic phase lengths of the bottom electrode layer, the piezoelectric layer, the top electrode layer, the dielectric layer, and the passivation layer of the resonator. The acoustic phase length of the dielectric layer of the fundamental resonator and the harmonic resonator approaches π×(n - 1). The thickness of the dielectric layer of the harmonic resonator is greater than the thickness of the dielectric layer of the fundamental resonator.

2. The filter integrating a fundamental resonator and a harmonic resonator according to claim 1, characterized in that, The fundamental wave resonator serves as a parallel resonator in the filter, and the harmonic resonator serves as a series resonator in the filter.

3. The filter integrating a fundamental resonator and a harmonic resonator according to claim 1, characterized in that, The filter is a bulk acoustic wave filter.

4. The filter integrating a fundamental resonator and a harmonic resonator according to claim 1, characterized in that, The dielectric layer is used for frequency tuning and frequency temperature coefficient compensation.

5. The filter integrating a fundamental resonator and a harmonic resonator according to claim 1, characterized in that, The fundamental wave resonator and the harmonic resonator are solid-mounted resonators, or the fundamental wave resonator and the harmonic resonator are thin film bulk acoustic wave resonators.

6. The filter integrating a fundamental resonator and a harmonic resonator according to claim 1, characterized in that, The reflectors, bottom electrode layers, piezoelectric layers, and top electrode layers of the fundamental wave resonator and the harmonic resonator have the same thickness.

7. The filter integrating a fundamental resonator and a harmonic resonator according to claim 1, characterized in that, It further includes a seed layer located on the reflector, under the bottom electrode layer and the piezoelectric layer, and the material of the seed layer includes aluminum nitride.

8. The filter integrating a fundamental resonator and a harmonic resonator according to claim 1, characterized in that, The material of the piezoelectric layer includes scandium-doped aluminum nitride.

9. A manufacturing method of a filter integrating a fundamental resonator and a harmonic resonator, characterized in that, The fundamental wave resonator and the harmonic resonator are resonators in a thickness-extensional vibration mode, and the harmonic order of the harmonic resonator is not less than 2. The method includes: Obtaining a wafer formed with a reflector, a bottom electrode layer, a piezoelectric layer, and a top electrode layer stacked in sequence; Forming dielectric layers with different thicknesses in regions of the wafer for forming different resonators; the acoustic phase lengths of the dielectric layers of the fundamental wave resonator and the harmonic resonator approach π(n - 1), where n is the harmonic order of the resonator in the thickness-extensional vibration mode; Form a passivation layer covering the dielectric layer; the stack acoustic phase length h of the resonator ph Approaches πn, the stack acoustic phase length h ph Is the sum of the acoustic phase lengths of the bottom electrode layer, piezoelectric layer, top electrode layer, dielectric layer, and passivation layer of the resonator; Among them, the single chip of the wafer includes the fundamental wave resonator and the harmonic resonator.

10. The manufacturing method of a filter integrating a fundamental resonator and a harmonic resonator according to claim 9, characterized in that, Before the step of obtaining the wafer formed with a reflector, a bottom electrode layer, a piezoelectric layer, and a top electrode layer stacked in sequence, it further includes: Determining the structural parameters of the reflector according to the frequency range of the passband of the filter to achieve frequency screening of acoustic waves; Adjusting the structural parameters of the bottom electrode layer, piezoelectric layer, top electrode layer, dielectric layer, and passivation layer through simulation to balance the electromechanical coupling and frequency characteristics of the fundamental wave resonator and the harmonic resonator; Further adjusting the structural parameters of each film layer of the filter through simulation to optimize the resonator performance and meet the design specifications.

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