Filter integrating fundamental and harmonic resonators and method of manufacturing the same

Abstract

The application relates to a filter integrating a fundamental resonator and a harmonic resonator and a manufacturing method thereof, the fundamental resonator and the harmonic resonator are resonators of thickness extensional vibration mode, the single crystal of the fundamental resonator and the harmonic resonator is integrated on a single chip, the stack acoustic phase length h of the fundamental resonator and the harmonic resonator is ph tends to pi*n, n is a harmonic order, the dielectric layer acoustic phase length of the fundamental resonator and the harmonic resonator tends to pi (n-1). The application sets the dielectric layer with different thicknesses in the fundamental resonator area and the harmonic resonator area, the dielectric layer acoustic phase length of the fundamental resonator and the harmonic resonator is pi (n-1), the fundamental resonator and the harmonic resonator are integrated on a single chip, so that a wider frequency range and a more suitable electromechanical coupling are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resonators, and in particular to a filter integrating a fundamental resonator and a harmonic resonator, and a manufacturing method of the filter integrating the fundamental resonator and the harmonic resonator. BACKGROUND

[0002] Resonators and filters based on micro-electro-mechanical 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 ease of mass production. New generation communication standards require higher data rates, which inevitably requires the passband of the filter 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 the next generation of applications because they can meet the requirements of high frequency operation, wideband function, low loss and strict power requirements.

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

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

[0005] Therefore, it is necessary to provide a filter integrating a fundamental resonator and a harmonic resonator and a manufacturing method thereof to balance a wider frequency range and more suitable 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 of thickness extensional mode, and the harmonic resonator is of a harmonic order not less than 2, the fundamental resonator and the harmonic resonator are monocrystal integrated on a single chip, the filter comprises, in sequence, a mirror, a bottom electrode layer, a piezoelectric layer, a top electrode layer, a dielectric layer and a passivation layer, the stack acoustic phase length h of the fundamental resonator and the harmonic resonator is ph tending to πn, n being the harmonic order, the stack acoustic phase length h of the fundamental resonator and the harmonic resonator is ph the sum of the bottom electrode layer acoustic phase length, the piezoelectric layer acoustic phase length, the top electrode layer acoustic phase length, the dielectric layer acoustic phase length and the passivation layer acoustic phase length of the resonator, the dielectric layer acoustic phase length of the fundamental resonator and the harmonic resonator tends to π(n-1), and the thickness of the dielectric layer of the harmonic resonator is greater than the thickness of the dielectric layer of the fundamental resonator.

[0007] The filter integrating the fundamental resonator and the harmonic resonator, by setting the dielectric layers of different thicknesses in the fundamental resonator region and the harmonic resonator region, makes the dielectric layer acoustic phase lengths of the fundamental resonator and the harmonic resonator π(n-1), integrates the fundamental resonator and the harmonic resonator on a single chip, and thus realizes a wider frequency range and a more suitable electromechanical coupling.

[0008] In one of the embodiments, 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 of the embodiments, the filter is a bulk acoustic wave filter.

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

[0011] In one of the embodiments, the fundamental resonator and the harmonic resonator are solid mounted resonators.

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

[0013] In one of the embodiments, the thicknesses of the mirror, the bottom electrode layer, the piezoelectric layer and the top electrode layer of the fundamental resonator and the harmonic resonator are the same.

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

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

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

[0017] A manufacturing method of a filter integrating a fundamental resonator and a harmonic resonator, the fundamental resonator and the harmonic resonator being resonators of thickness-extensional vibration mode, and the harmonic resonator having a harmonic order not less than 2, the method comprising: obtaining a wafer formed with sequentially stacked mirrors, bottom electrode layers, piezoelectric layers, and top electrode layers; forming dielectric layers with different thicknesses in regions of the wafer for forming different resonators; the dielectric layers of the fundamental resonator and the harmonic resonator having an acoustic phase length tending to π(n-1), n being the harmonic order of the resonator of thickness-extensional vibration mode; forming a passivation layer covering the dielectric layers; the stack acoustic phase length h ph tending to πn, the stack acoustic phase length h ph being the sum of the acoustic phase length of the bottom electrode layer, the acoustic phase length of the piezoelectric layer, the acoustic phase length of the top electrode layer, the acoustic phase length of the dielectric layer, and the acoustic phase length of the passivation layer of the resonator; wherein the wafer includes the fundamental resonator and the harmonic resonator on a single chip.

[0018] The manufacturing method of the filter integrating the fundamental resonator and the harmonic resonator, by forming the dielectric layers with different thicknesses in the regions of the fundamental resonator and the harmonic resonator, makes the dielectric layers of the fundamental resonator and the harmonic resonator have an acoustic phase length of π(n-1), and integrates the fundamental resonator and the harmonic resonator on a single chip, thereby realizing a wider frequency range and a more suitable electromechanical coupling.

[0019] In one of the embodiments, before the step of obtaining the wafer formed with sequentially stacked mirrors, bottom electrode layers, piezoelectric layers, and top electrode layers, the method further comprises: determining the structural parameters of the mirrors according to the frequency range of the passband of the filter, to realize frequency screening of acoustic waves; adjusting the structural parameters of the bottom electrode layers, the piezoelectric layers, the top electrode layers, the dielectric layers, and the passivation layers through simulation, to balance the electromechanical coupling and the frequency characteristics of the fundamental resonator and the harmonic resonator; and further adjusting the structural parameters of each film layer of the filter through simulation, to optimize the performance of the resonator and meet the design specifications.

[0020] In one of the embodiments, in the step of obtaining the wafer formed with sequentially stacked mirrors, bottom electrode layers, piezoelectric layers, and top electrode layers, the thicknesses of the mirrors, the bottom electrode layers, the piezoelectric layers, and the top electrode layers in the regions for forming different resonators are the same.

[0021] In one of the embodiments, after forming the passivation layer, the method further comprises a step of cutting the wafer into chips by scribing, and each chip comprises the fundamental resonator and the harmonic resonator. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

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

[0024] Figure 2a is a circuit topology structure of a ladder filter in an embodiment of the present application, Figure 2b is a broadband filter response of the circuit topology structure shown in Figure 2a is a narrowband filter response of the circuit topology structure shown in Figure 2c Figure 2a

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

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

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

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

[0029] Figure 7 is a curve diagram of the electromechanical coupling of the resonators of TE1 and TE2 varying with frequency when the thickness of the dielectric layer varies.

[0030] Figure 8a is a conductance response curve of TE1 when the thickness of the dielectric layer is 110 nm, 65 nm and 5 nm respectively, Figure 8b is a conductance response curve of TE2 when the thickness of the dielectric layer is 560 nm, 480 nm and 400 nm respectively. DETAILED DESCRIPTION ​​​

[0031] For the purposes of this application, the application will now be described in more detail with reference to the enclosed drawings. In the drawings, embodiments of the application are shown. The application can be implemented in numerous different forms, however, and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art.

[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 art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0033] It should be understood that when an element or layer is referred to as being "on" or "adjacent" or "connected" or "coupled" to another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer or one or more intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on," "directly adjacent," "directly connected" or "directly coupled" to another element or layer, there are no intervening elements or layers present. It will be appreciated that, although terms such as first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms as these terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section; for example, a first dopant type could be termed a second dopant type, and similarly, a second dopant type could be termed a first dopant type; a first dopant type and a second dopant type are different dopant types, for example, a first dopant type could be P-type and a second dopant type could be N-type, or a first dopant type could be N-type and a second dopant type could be P-type.

[0034] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and / or operation in addition to the orientations depicted in the figures. For example, if a device in the figures is inverted, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The devices can be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0035] As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. As should also be apparent, the term "comprising" or "containing" or "having" or the like means containing at least the stated feature, integer, step, operation, component, or combination thereof, but does not exclude the presence or addition of one or more other features, integers, steps, operations, components, or combinations thereof.

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

[0037] The present application introduces a platform that overcomes the limitations of conventional TE1 mode BAW (Bulk Acoustic Wave) filter designs by integrating resonators operating in both the fundamental thickness extensional mode (first order thickness extensional, TE1, harmonic order of 1) and the harmonic thickness extensional mode (TE2, TE3, etc.) on a single acoustic die. By allowing the thickness of the dielectric layer on the top electrode layer in the resonator stack to be adjusted, the platform enables seamless transitions between modes, resulting in a wider frequency range and more appropriate electromechanical coupling. The fundamental mode uses a thin resonant cavity, while the harmonic mode uses a thicker resonant cavity. This approach provides a flexible platform for designing BAW filters suitable for a variety of applications.

[0038] Figure 1 is a structural schematic 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 thickness extensional resonators, and the harmonic order of the harmonic resonator is not less than 2 (i.e., it can be a second-order TE2, a third-order TE3, a fourth-order TE4, etc.), and the single-crystal fundamental resonator and the single-crystal harmonic resonator are integrated on a single die. 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, which are sequentially stacked. The acoustic phase length h ph of the stack of the fundamental resonator and the harmonic resonator is close to (approximately equal to) πn, n is the harmonic order of the thickness extensional resonator, h ph is the sum of the acoustic phase length of the bottom electrode layer, the acoustic phase length of the piezoelectric layer, the acoustic phase length of the top electrode layer, the acoustic phase length of the dielectric layer, and the acoustic phase length of the passivation layer of the resonator, and the acoustic phase length h pht of the dielectric layer of the fundamental resonator and the harmonic resonator is close to (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 the half wavelength of each resonator.h ph is close to πn, h pht is close to π(n-1), which means that the inventors believe that h ph = πn, h pht = π, the resonator theoretically has the best electromechanical coupling performance, but in actual production, the acoustic phase length (corresponding thickness) of the film layer can also deviate slightly from the theoretical value due to process errors and other reasons.

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

[0040] The filter integrating the fundamental resonator and the harmonic resonator, by setting the dielectric layer 160 with different thickness in the fundamental resonator region and the harmonic resonator region, so that the acoustic phase length of the dielectric layer of the fundamental resonator and the harmonic resonator is π (n-1), integrates the fundamental resonator and the harmonic resonator on a single chip, so as to realize a wider frequency range and a more suitable electromechanical coupling.

[0041] Referring to Figure 2a In an embodiment of the present application, the fundamental resonator and the harmonic resonator constitute a ladder filter, the fundamental resonator as a parallel resonator in the ladder filter, and the harmonic resonator as a series resonator in the ladder filter. Figure 2b is the wideband filter response of the circuit topology shown in Figure 2a Figure 2c is the narrowband filter response with superimposed resonator response of the circuit topology shown in Figure 2a Figure 2c For each curve in

[0042] In another embodiment of the present application, the fundamental resonator can also be a series resonator in the ladder filter, and the harmonic resonator can be a parallel 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 can 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 can 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 1 ​​In the shown 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 can also have a patterned high acoustic impedance layer 124 and / or a patterned low acoustic impedance layer 122. In some embodiments, the low acoustic impedance material of the low acoustic impedance layer 122 can 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 can be at least one of molybdenum, tungsten, titanium, platinum, aluminum nitride, aluminum oxide, tungsten oxide, and silicon nitride; it can be appreciated that in other embodiments, other material combinations with a larger impedance ratio can also be used for the low acoustic impedance material and the high acoustic impedance material.

[0045] Figure 3 Figure 2 is a plot of the transmittance of a Bragg acoustic mirror as a function of frequency. The acoustic Bragg mirror is composed of three pairs of alternating SiO2layers (low acoustic impedance layer 122) and AlN layers (high acoustic impedance layer 124), and is formed on a silicon (Si) substrate. An additional top SiO2layer is added to the mirror. The thicknesses of the layers are: 260 nm for the bottom three SiO2layers, 480 nm for the bottom three AlN layers, and 280 nm for the top SiO2layer.

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

[0047] In one embodiment of the present application, the thicknesses of the mirror 120, the bottom electrode layer 130, the piezoelectric layer 140, and the top electrode layer 150 of the fundamental resonator and the harmonic resonator are the same, and the different stack acoustic phase lengths h ph .

[0048] In one embodiment of the present application, the harmonic resonator includes at least two resonators with different harmonic orders, for example, a TE2resonator and a TE3resonator.

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

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

[0051] In an embodiment of the present application, the top surface of the top electrode layer 150 is provided with a diffusion barrier layer, the material of the diffusion barrier layer being Ti.

[0052] In an embodiment of the present application, the filter further comprises a Ti frame layer 152 on the top electrode layer 150, the top electrode layer 150 and the Ti frame layer 152 being covered by the passivation layer 170.

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

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

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

[0056] S110, obtaining a wafer formed with a mirror, a bottom electrode layer, a piezoelectric layer and a top electrode layer sequentially stacked.

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

[0058] S120, forming dielectric layers with different thicknesses in the areas of different resonators of the wafer.

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

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

[0061] The stack acoustic phase length h of the resonator ph Approaches (i.e. approximately equal to) π(n-1), n is the harmonic order of the resonator of the thickness extension vibration mode. The stack acoustic phase length h ph The sum of the bottom electrode layer acoustic phase length, the piezoelectric layer acoustic phase length, the top electrode layer acoustic phase length, the dielectric layer acoustic phase length and the passivation layer acoustic phase length of the resonator. The total thickness of the stack (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 n times the half wavelength of each resonator.

[0062] In an embodiment of the present application, after step S130, further comprising the step of cutting the wafer into individual chips (Die) by dicing, and each chip includes a fundamental resonator and a harmonic resonator.

[0063] The manufacturing method of the above-mentioned filter structure integrating the fundamental resonator and the harmonic resonator, by forming dielectric layers of different thicknesses in the fundamental resonator region and the harmonic resonator region, the dielectric layer acoustic phase lengths of the fundamental resonator and the harmonic resonator are π(n-1), the fundamental resonator and the harmonic resonator are integrated into a single chip, thereby realizing 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, 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 higher levels of customized optimization of key performance indicators.

[0064] In an embodiment of the present application, before step S120, further comprising the 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, further comprising the step of forming a Ti frame layer 152 on the top electrode layer 150.

[0066] Referring to Figure 5 In an embodiment of the present application, before step S110, further comprising the step of structurally designing the filter, specifically including:

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

[0068] Based on the frequency range of the filter's passband, the structural parameters of reflector 120 are determined to achieve frequency filtering of acoustic waves. Creating reflector 120 with optimal reflectivity characteristics for the defined passband ensures effective energy confinement when necessary and allows energy to pass when not required.

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

[0070] Through simulation, the structural parameters (including shape, pattern, and dimensions) of the stack above the reflector 120 (including the bottom electrode layer 130, piezoelectric layer 140, top electrode layer 150, dielectric layer 160, and passivation layer 170) are adjusted and optimized to balance the electromechanical coupling and frequency characteristics of the fundamental mode (corresponding to the fundamental resonator) and the harmonic modes (corresponding to the harmonic resonators). These resonators operating in different modes share the same membrane layers within the chip. The thicknesses of the various membrane layers can be finely tuned, while only the thickness of the dielectric layer 160 can be significantly varied to achieve transitions between the modes.

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

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

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

[0074] S106, further adjust the structure parameters of the stack to optimize the resonator performance and meet the design specifications.

[0075] The structure parameters of each film layer of the filter are modified 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 is adjusted to reflect shear wave components in addition to the longitudinal wave components, or spurious modes are suppressed, among other improvements.

[0076] After step S106 is completed, steps S110 to S130 are performed to manufacture the filter based on the adjusted structure parameters of each film layer of the filter.

[0077] Based on all the above embodiments, the filter of the present embodiment, which integrates fundamental resonators and harmonic resonators, has the following advantages:

[0078] Increased frequency range: By combining fundamental resonators and harmonic resonators, the frequency range of high electromechanical coupling is expanded, allowing for a wider resonant frequency with a larger bandwidth.

[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, thereby providing greater flexibility for filter design.

[0080] Good thermal stability: The harmonic 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 a wide range of frequency and performance characteristics, making it useful for filter design.

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

[0083] Reduced cost: minimizes the need for complex multi-chip processing, simplifies the manufacturing flow and reduces its cost.

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

[0085] By adjusting the resonator cavity size, a wide frequency range and diverse electromechanical coupling can be achieved, enabling the resonator to operate in different bulk acoustic wave vibration modes. For example, a resonator with a thin cavity (defined primarily by the piezoelectric layer) supports a thickness-extended fundamental mode (TE1), while a resonator with a thick cavity supports thickness-extended harmonic modes (TE2, TE3, etc.). The thickness-extended harmonic modes are defined primarily by the piezoelectric layer 140 and the dielectric layer 160, which is also typically used to stabilize the resonator's performance with respect to temperature.

[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 design center frequency, to maximize the electromechanical coupling coefficient. The TE1 vibration mode is composed of only the half-wavelength portion of the film layers, while the harmonic vibration modes include an additional half-wavelength portion (extending to the film layers from the top electrode layer 150 to the passivation layer 170) to complete the respective harmonic order.

[0087] While it is possible to modify parameters such as frequency, electromechanical coupling, capacitance, and frequency temperature coefficient (TCF) by adjusting the film layers, the main advantage of this platform is the ability to adjust the frequency and coupling characteristics of the resonator by changing the thickness of the dielectric layer 160 above the top electrode layer 150. The dielectric layer 160 is typically used to improve the TCF and enable smooth transitions between different resonator cavities, supporting seamless transitions between the fundamental vibration mode and the harmonic vibration modes. This provides higher flexibility for resonator design and overall performance. At the same time, the present application also provides a solution for integrating resonators of a wider frequency range to achieve a filter with a wide frequency and large bandwidth on a single chip.

[0088] The method for manufacturing the filter integrating the fundamental resonator and the harmonic resonator of the present application is based on the same inventive concept as the filter integrating the fundamental resonator and the harmonic resonator, and the contents not specifically described in the method for manufacturing the filter integrating the fundamental resonator and the harmonic resonator can be referred to the foregoing description of the filter integrating the fundamental resonator and the harmonic resonator.

[0089] It should be understood that, although the steps in the flowcharts of the present application are shown in a sequence according to the arrows, the steps are not necessarily executed in the sequence according to the arrows. Unless otherwise specified herein, the execution of the steps is not necessarily limited in sequence, and the steps can be executed in other sequences. Moreover, at least some of the steps in the flowcharts of the present application can include multiple steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of the steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least some of the other steps or the steps or stages in the other steps.

[0090] In the description of the present application, the description of the terms "some embodiments", "other embodiments", "ideal embodiments", and the like means that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0091] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, not all possible combinations of the technical features of the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present application.

[0092] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are within the protection scope of the present application. Therefore, the patent protection scope of the present application should 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 of thickness extension vibration mode, and the harmonic order of the harmonic resonator is not less than 2. The fundamental resonator and the harmonic resonator are integrated into a single chip. The filter includes a reflector, 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 is ph Approaching π×n, n is the harmonic order, the stack acoustic phase length h ph It is the sum of the acoustic phase length of the bottom electrode layer, the acoustic phase length of the piezoelectric layer, the acoustic phase length of the top electrode layer, the acoustic phase length of the dielectric layer and the acoustic phase length of 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), where n is the harmonic order. The fundamental resonator is used to operate in the fundamental mode, and the harmonic resonator is used to operate in the harmonic mode. 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 fundamental resonator and harmonic resonator according to claim 1, characterized in that: The fundamental 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 fundamental resonator and harmonic resonator according to claim 1, characterized in that: The filter is a bulk acoustic wave filter.

4. The filter integrating fundamental wave resonator and harmonic wave 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 fundamental resonator and harmonic resonator according to claim 1, characterized in that: The fundamental wave resonator and the harmonic wave resonator are fixed resonators, or the fundamental wave resonator and the harmonic wave resonator are thin film bulk acoustic resonators.

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

7. The filter integrating fundamental wave resonator and harmonic wave resonator according to claim 1, characterized in that: The invention also includes a seed layer located on the reflecting mirror and below the bottom electrode layer and the piezoelectric layer, wherein the material of the seed layer includes aluminum nitride.

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

9. A method for manufacturing a filter integrating a fundamental resonator and a harmonic resonator, characterized in that: The fundamental resonator and the harmonic resonator are resonators of thickness extension vibration mode, and the harmonic order of the harmonic resonator is not less than 2. The method includes: Obtaining a wafer having a reflective mirror, a bottom electrode layer, a piezoelectric layer, and a top electrode layer stacked in sequence; Dielectric layers of different thicknesses are formed in regions of the wafer used to form 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 the thickness extension vibration mode; A passivation layer is formed covering the dielectric layer; the stack acoustic phase length h of the resonator ph Approaching πn, 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, a single chip of the wafer includes the fundamental wave resonator and the harmonic resonator, the fundamental wave resonator is used to operate in a fundamental wave mode, and the harmonic resonator is used to operate in a harmonic mode.

10. The method for manufacturing a filter integrating fundamental resonators and harmonic resonators according to claim 9, characterized in that: Before the step of obtaining a wafer having a reflective mirror, a bottom electrode layer, a piezoelectric layer, and a top electrode layer stacked in sequence, the method further includes: Determining the structural parameters of the reflector according to the frequency range of the filter's passband to achieve frequency screening of the acoustic wave; 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; The structural parameters of each membrane layer of the filter are further adjusted through simulation to optimize the resonator performance and meet the design specifications.

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