A surface acoustic wave filter, electronic component, and electronic device

Abstract

The embodiment of the present specification provides a surface acoustic wave filter, which comprises a first resonator and a second resonator, wherein a dielectric layer is arranged between a piezoelectric layer and an interdigital transducer of the first resonator, so that the bandwidth of the first resonator can be adjusted by adjusting the thickness of the dielectric layer, and the rectangularity of the left side, the right side or both sides of the surface acoustic wave filter can be selectively improved, thereby achieving the purpose of improving the rectangularity of the surface acoustic wave filter. In addition, the dielectric layer comprises a high acoustic impedance material layer, and under the same thickness change, the change of the bandwidth and frequency offset of the high acoustic impedance material layer is smaller than that of a low acoustic impedance material layer, so that the process sensitivity of the device can be reduced by comprising the high acoustic impedance material layer, and the adverse effects of process errors on the target bandwidth of the design are weakened.

Description

Technical Field

[0001] This specification relates to the field of semiconductor technology, specifically to surface acoustic wave (SAW) filter technology within the semiconductor technology field, and more specifically to a SAW filter, electronic components, and electronic devices. Background Technology

[0002] Acoustic wave devices are a class of devices that utilize the properties of sound waves propagating in a medium to achieve various functions. Acoustic wave devices are widely used in fields such as communication, signal processing, and sensors.

[0003] Taking surface acoustic wave (SAW) filters as an example, rectangularity is an indicator of whether the frequency response of a SAW filter closely approximates the ideal rectangular characteristic, reflecting the steepness of the transition band. High rectangularity means a steeper transition between the passband and stopband of the SAW filter. This allows the SAW filter to more effectively suppress nearby interference signals while allowing the target signal to pass, thereby improving signal purity and quality. Therefore, it is necessary to improve the rectangularity of SAW filters to improve device performance. Utility Model Content

[0004] This specification provides an embodiment of a surface acoustic wave filter, electronic components, and electronic equipment to improve the rectangularity of the surface acoustic wave filter.

[0005] To achieve the above technical objectives, the embodiments of this specification provide the following technical solutions:

[0006] In one aspect, one embodiment of this specification provides a surface acoustic wave filter, comprising: a first resonator and a second resonator; wherein...

[0007] Both the first resonator and the second resonator include: a substrate, a piezoelectric layer located on one side of the substrate, and an interdigital transducer located on the side of the piezoelectric layer opposite to the substrate;

[0008] The first resonator further includes a dielectric layer located between the piezoelectric layer and the interdigital transducer, the dielectric layer comprising a high acoustic impedance material layer.

[0009] Optionally, the thickness of the dielectric layer ranges from 5 nm to 30 nm.

[0010] Optionally, the piezoelectric layer of the first resonator and the piezoelectric layer of the second resonator are a shared piezoelectric layer.

[0011] Optionally, the high acoustic impedance material layer includes a material layer with an acoustic impedance greater than 30 MRayl.

[0012] Optionally, the high acoustic impedance material layer includes a material layer with an acoustic impedance greater than 45 MRayl.

[0013] Optionally, the high acoustic impedance material layer includes at least one of the following: a platinum metal layer, a tungsten metal layer, a tantalum metal layer, an iridium metal layer, a rhenium metal layer, a silicon nitride layer, and a molybdenum metal layer.

[0014] Optionally, both the first resonator and the second resonator further include: a reflective grating;

[0015] The reflective grating is located on both sides of the interdigital transducer in a first direction, which intersects the extension direction of the interdigital electrodes in the interdigital transducer.

[0016] Optionally, both the first resonator and the second resonator further include: a temperature compensation layer, a protective layer, and a low-velocity sound layer; wherein,

[0017] The temperature compensation layer is located on the side of the interdigital transducer away from the substrate, and the protective layer is located on the side of the temperature compensation layer away from the substrate.

[0018] The low-velocity layer is located between the substrate and the piezoelectric layer.

[0019] Secondly, one embodiment of this specification provides an electronic component including one or more surface acoustic wave filters as described in any of the preceding claims.

[0020] Thirdly, one embodiment of this specification also provides an electronic device, comprising:

[0021] A transceiver for receiving or transmitting signals, the transceiver comprising electronic components as described in any of the preceding claims;

[0022] A processor for processing the signal, wherein the processor is coupled to the transceiver.

[0023] As can be seen from the above technical solution, the surface acoustic wave (SAW) filter provided in this embodiment includes a first resonator and a second resonator. A dielectric layer is disposed between the piezoelectric layer and the interdigital transducer of the first resonator. Thus, the bandwidth of the first resonator can be adjusted by regulating the thickness of the dielectric layer, selectively improving the rectangularity of the left, right, or both sides of the SAW filter, thereby achieving the goal of improving the rectangularity of the SAW filter. Furthermore, the dielectric layer includes a high acoustic impedance material layer, based on the acoustic impedance formula: Z = ρ × v (material density ρ × sound velocity v) and the reflection coefficient... It is known that the greater the difference in acoustic impedance between two layers (e.g., a piezoelectric layer and a dielectric layer), the stronger the reflection and the higher the energy loss. When a dielectric layer is inserted between an interdigital transducer and a piezoelectric layer, the degree of matching between the acoustic impedance of the dielectric layer and the acoustic impedance of the piezoelectric layer determines the propagation loss and energy coupling efficiency of surface acoustic waves. High acoustic impedance material layers, because their acoustic impedance is closer to that of the piezoelectric layer, reduce interface reflection and energy loss. The thickness variation has a smaller impact on the electromechanical coupling coefficient and propagation path, resulting in smaller bandwidth and frequency shift. That is, under the same thickness variation, the bandwidth and frequency shift of a high acoustic impedance material layer are smaller than those of a low acoustic impedance material layer. Therefore, including a high acoustic impedance material layer in the dielectric layer can reduce the device's process sensitivity and mitigate the adverse effects of process errors on the designed target bandwidth. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this specification. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 A schematic diagram of the structure of a surface acoustic wave filter provided for one embodiment of this specification;

[0026] Figure 2 A cross-sectional structural schematic diagram of a first resonator and a second resonator provided for one embodiment of this specification;

[0027] Figure 3 A top view of a resonator provided for one embodiment of this specification;

[0028] Figure 4 A simulation structure diagram of a resonator with different dielectric layer thicknesses is provided as one embodiment of this specification;

[0029] Figure 5 A schematic diagram showing the relationship between the resonant frequency of a first resonator and the thickness of the dielectric layer, provided for one embodiment of this specification;

[0030] Figure 6 A schematic diagram showing the relationship between the relative bandwidth of a first resonator and the thickness of the dielectric layer, provided for one embodiment of this specification;

[0031] Figure 7 A performance comparison diagram of the surface acoustic wave filter provided in the embodiments of this specification and the surface acoustic wave resonator provided in the comparative examples;

[0032] Figure 8 A comparison diagram of the right edge passband performance of the surface acoustic wave filter provided in the embodiments of this specification and the surface acoustic wave resonator provided in the comparative examples;

[0033] Figure 9 This is a schematic diagram of another surface acoustic wave filter provided as one embodiment of this specification.

[0034] Explanation of reference numerals in the attached figures:

[0035] 100 - Surface acoustic wave filter; 101 - Series resonator; 102 - Parallel resonator; 110 - First resonator; 120 - Second resonator;

[0036] 10 - Substrate; 20 - Piezoelectric layer; 30 - Dielectric layer; 40 - Interdigital transducer; 50 - Reflective grating. Detailed Implementation

[0037] Unless otherwise defined, the technical or scientific terms used in the embodiments of this specification shall have the ordinary meaning understood by one of ordinary skill in the art to which this specification pertains. The terms "first," "second," and similar terms used in the embodiments of this specification do not indicate any order, quantity, or importance, but are merely used to avoid confusion of constituent elements.

[0038] Unless the context otherwise requires, throughout this specification, "a plurality of" means "at least two," and "including" is interpreted as open-ended or encompassing, that is, "including, but not limited to." In the description of this specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this specification. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example.

[0039] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification.

[0040] Overview

[0041] The commercialization of 5G technology and the research and development of 6G technology have placed higher demands on wireless communication systems. 5G communication requires higher data transmission rates, lower latency, and a larger number of connections, which necessitates higher performance filters. Surface Acoustic Wave (SAW) filters, due to their simple structure, fewer mask layers, ease of miniaturization, and low cost, are widely used in home televisions, mobile communications, RF filters, and radar. The explosive growth of transmitted data in the 5G era places higher demands on the bandwidth of SAW filters. This requires filters with higher frequency selectivity, lower insertion loss, and better temperature stability. High-rectangularity filters can more effectively suppress adjacent channel interference and improve signal quality. High-rectangularity filters have steeper roll-off characteristics, which can more effectively suppress unwanted frequency components, improve spectrum utilization, and reduce interference between different devices. In related technologies, to adjust the bandwidth of a SAW filter, a capacitor can be connected in parallel across the SAW resonator, and the bandwidth of the SAW filter can be adjusted by changing the size of the capacitor. However, this method is not conducive to the miniaturization of surface acoustic wave filters because the capacitor itself occupies a large area, resulting in a high overall device cost.

[0042] To address this issue, the inventors conducted a detailed study on the structure and bandwidth adjustment principle of surface acoustic wave (SAW) filters. Two types of resonators (which can be referred to as the first resonator and the second resonator) can be incorporated into the SAW filter. A dielectric layer is inserted between the piezoelectric layer and the interdigital transducer of the first resonator. By adjusting the thickness of the dielectric layer, the propagation loss and energy coupling efficiency of the SAW waves in the first resonator can be controlled, thereby adjusting the bandwidth of the SAW filter. This allows for selective improvement of the rectangularity of the left, right, or both sides of the SAW filter. Furthermore, the influence of inserting different acoustic impedance material layers as dielectric layers into the first resonator was investigated, based on the acoustic impedance formula: Z = ρ × v (material density ρ × sound velocity v) and the reflection coefficient. It is known that the greater the difference in acoustic impedance between two layers (e.g., a piezoelectric layer and a dielectric layer), the stronger the reflection and the higher the energy loss. When a dielectric layer is inserted between an interdigital transducer and a piezoelectric layer, the degree of matching between the acoustic impedance of the dielectric layer and the acoustic impedance of the piezoelectric layer determines the propagation loss and energy coupling efficiency of surface acoustic waves. High acoustic impedance material layers, because their acoustic impedance is closer to that of the piezoelectric layer, reduce interface reflection and energy loss. The thickness variation has a smaller impact on the electromechanical coupling coefficient and propagation path, resulting in smaller bandwidth and frequency shift. That is, under the same thickness variation, the bandwidth and frequency shift of a high acoustic impedance material layer are smaller than those of a low acoustic impedance material layer. Therefore, including a high acoustic impedance material layer in the dielectric layer can reduce the device's process sensitivity (process sensitivity refers to the sensitivity of key device performance parameters (such as resonant frequency f, bandwidth Δf, etc.) to parameter fluctuations during manufacturing (such as material thickness deviation, interface roughness, temperature changes, etching accuracy, etc.)) and mitigate the adverse effects of process errors on the designed target bandwidth. In the manufacturing process of micro- and nano-electronic devices (such as surface acoustic wave resonators and filters), process errors may cause discrepancies between the actual film thickness and the designed thickness. Higher process sensitivity means that even small process errors (such as a 1nm thickness deviation) can lead to significant deviations in device performance from the design target (such as a frequency shift of hundreds of kHz). Conversely, lower process sensitivity means that the device performance is more tolerant of process errors, making large-scale, highly consistent mass production easier. Therefore, reducing the process sensitivity of devices is crucial for ensuring device performance.

[0043] Based on the above concept, this specification provides a surface acoustic wave filter. The surface acoustic wave filter provided in this specification will be described exemplarily below with reference to the accompanying drawings.

[0044] Exemplary Filter

[0045] This specification provides a surface acoustic wave filter 100, such as... Figure 1 and Figure 2 As shown, it includes: a first resonator 110 and a second resonator 120; wherein, the first resonator 110 and the second resonator 120 each include: a substrate 10, a piezoelectric layer 20 located on one side of the substrate 10, and an interdigital transducer 40 located on the side of the piezoelectric layer 20 opposite to the substrate 10.

[0046] The first resonator 110 further includes a dielectric layer 30, which is located between the piezoelectric layer 20 and the interdigital transducer 40, and the dielectric layer 30 includes a high acoustic impedance material layer.

[0047] The surface acoustic wave filter 100 may include a series resonator 101 and a parallel resonator 102, and the number of both the series resonator 101 and the parallel resonator 102 may be multiple, for example, reference... Figure 1 In one embodiment, the surface acoustic wave filter 100 may include seven resonators named SNP1 to SNP7, which together form a seventh-order trapezoidal filter. It is understood that... Figure 1 This specification only illustrates one feasible layout and connection method of the resonators in the surface acoustic wave (SAW) filter 100. In other embodiments, the SAW filter 100 may include more or fewer resonators. This specification does not limit the number, layout, or connection method of the resonators included in the SAW filter 100; it depends on the actual situation. Figure 1 In this embodiment, resonators named SNP1 to SNP4 are series resonators 101, and resonators named SNP5 to SNP7 are parallel resonators 102. In some embodiments, all series resonators 101 can be first resonators 110, and all parallel resonators 102 can be second resonators 120. However, in other embodiments, the series resonators 101 and the parallel resonators 102 can be either the first resonator 110 or the second resonator 120. This specification does not limit this, and the specific choice depends on the actual situation. The cross-sectional structures of the first resonator 110 and the second resonator 120 can be referred to... Figure 2 Both the first resonator 110 and the second resonator 120 may include structures such as a substrate 10, a piezoelectric layer 20, and an interdigital transducer 40. In addition, the first resonator 110 also includes a dielectric layer 30. The dielectric layer 30 may include a high acoustic impedance material layer, thus allowing for bandwidth adjustment of the first resonator 110 by adjusting the thickness of the dielectric layer 30. This selectively improves the rectangularity of the left, right, or both sides of the surface acoustic wave filter 100, achieving the goal of improving the rectangularity of the surface acoustic wave filter 100. Furthermore, the dielectric layer 30 includes a high acoustic impedance material layer, based on the acoustic impedance formula: Z = ρ × v (material density ρ × sound velocity v) and the reflection coefficient... It is known that the greater the difference in acoustic impedance between the two layers (e.g., piezoelectric layer 20 and dielectric layer 30), the stronger the reflection, and the higher the energy loss. When a dielectric layer 30 is inserted between the interdigital transducer 40 and the piezoelectric layer 20, the degree of matching between the acoustic impedance of the dielectric layer 30 and the acoustic impedance of the piezoelectric layer 20 determines the propagation loss and energy coupling efficiency of the surface acoustic wave. Because the high acoustic impedance material layer is closer to the acoustic impedance of the piezoelectric layer 20, it reduces interface reflection and energy loss. The thickness variation has a smaller impact on the electromechanical coupling coefficient and propagation path, resulting in smaller bandwidth and frequency shift. That is, under the same thickness variation, the bandwidth and frequency shift of the high acoustic impedance material layer are smaller than those of the low acoustic impedance material layer. Therefore, including a high acoustic impedance material layer in the dielectric layer 30 can reduce the device's process sensitivity and mitigate the adverse effects of process errors on the designed target bandwidth.

[0048] In one embodiment, the high acoustic impedance material layer may refer to a layer with an acoustic impedance greater than or equal to 30 MRayl (1 MRayl = 10 MRayl). 6 A high acoustic impedance material layer (HAIL) can be a material layer with an acoustic impedance greater than or equal to 35 MRayl. In yet another embodiment, the high acoustic impedance material layer can be a material layer with an acoustic impedance greater than or equal to 45 MRayl. These material layers may include at least one of platinum, tungsten, tantalum, iridium, rhenium, and molybdenum metal layers. In some embodiments, the high acoustic impedance material layer may also be a silicon nitride layer.

[0049] In one embodiment of this specification, the thickness of the dielectric layer 30 ranges from 5 nm to 30 nm. When the thickness of the dielectric layer 30 is within the above range, and the acoustic impedance of the high acoustic impedance material layer is greater than or equal to 30 MRayl, simulation verification shows that the dielectric layer 30 causes the 3dB bandwidth Δf of the first resonator 110 to decrease as the thickness d of the dielectric layer 30 increases, satisfying Δf ≤ -k2×d; k2 is an integer coefficient, and when the dielectric layer 30 includes a high acoustic impedance material layer, the value of k2 is smaller; while when the dielectric layer 30 includes a low acoustic impedance material layer, the value of k2 is larger; furthermore, the dielectric layer 30 causes the resonant frequency fs of the first resonator 110 to increase as the thickness d of the dielectric layer 30 increases, satisfying fs ≤ k4×d, and when the dielectric layer 30 includes a high acoustic impedance material layer, the value of k4 is smaller. That is, when the dielectric layer 30 includes a high acoustic impedance material layer, under the same thickness variation, the changes in bandwidth and frequency shift of the high acoustic impedance material layer are smaller than those of the low acoustic impedance material layer. Therefore, including a high acoustic impedance material layer in the dielectric layer 30 can reduce the device's process sensitivity and mitigate the adverse effects of process errors on the designed target bandwidth. In one embodiment, to ensure the adjustment function of the dielectric layer 30 on bandwidth and frequency, the width of the dielectric layer 30 can be greater than or equal to the width of the interdigital transducer 40. The width of the interdigital transducer 40 can refer to the dimension of the interdigital transducer 40 in the arrangement direction of its interdigital electrodes. Correspondingly, the width of the dielectric layer 30 can refer to the dimension of the dielectric layer 30 in the arrangement direction of its interdigital electrodes.

[0050] In one implementation, to simplify the process and ensure acoustic coupling consistency, reference is still made to... Figure 2 The piezoelectric layer 20 of the first resonator 110 and the piezoelectric layer 20 of the second resonator 120 are shared by the same piezoelectric layer 20. Thus, during the fabrication of the surface acoustic wave filter 100, the piezoelectric layers 20 of the first resonator 110 and the second resonator 120 can be formed in one fabrication process, thereby simplifying the process and ensuring acoustic coupling consistency.

[0051] In one embodiment, the piezoelectric layer 20 may include any one of a lithium tantalate layer, a lithium niobate layer, and a quartz layer. The chamfer angle of the lithium tantalate layer may be 30° to 50°, and the thickness of the piezoelectric layer 20 may range from 300 nm to 2000 nm. The material forming the interdigital transducer 40 may include at least one of titanium, chromium, copper, silver, and aluminum.

[0052] In one implementation, to improve the quality factor (Q value) of the surface acoustic wave filter 100, a reference is made. Figure 3The first resonator 110 and the second resonator 120 also each include a reflective grating 50;

[0053] The reflective grating 50 is located on both sides of the interdigital transducer 40 in a first direction, which intersects the extension direction of the interdigital electrodes in the interdigital transducer 40.

[0054] The reflective grating 50 can limit the propagation of surface acoustic waves in the resonant cavity, form the resonant cavity boundary, enhance energy localization, and improve the quality factor (Q value).

[0055] In one embodiment, both the first resonator 110 and the second resonator 120 further include: a temperature compensation layer, a protective layer, and a low-velocity sound layer; wherein...

[0056] The temperature compensation layer is located on the side of the interdigital transducer 40 away from the substrate 10, and the protective layer is located on the side of the temperature compensation layer away from the substrate 10.

[0057] The low-velocity layer is located between the substrate 10 and the piezoelectric layer 20.

[0058] The sound velocity in the low-velocity layer is less than the sound velocity in the piezoelectric layer 20, while the sound velocity in the substrate 10 is greater than the sound velocity in the piezoelectric layer 20.

[0059] The low-velocity layer can confine the acoustic energy on the surface of the piezoelectric layer 20, reducing the leakage of acoustic waves to the substrate 10, thereby helping to improve the Q value and electromechanical coupling efficiency of the resonator.

[0060] The temperature compensation layer can suppress the frequency drift of the resonator and improve temperature stability (which is especially important for 5G high-frequency filters).

[0061] In one specific embodiment, a feasible surface acoustic wave (SAW) filter 100 structure is provided, wherein the series resonators 101 in the SAW filter 100 are all first resonators 110, and the parallel resonators 102 in the SAW resonators are all second resonators 120. The piezoelectric layer 20 can be a lithium tantalate layer or a lithium niobate layer. The chamfer angle of the lithium tantalate layer can be 30° to 50°. The piezoelectric layer 20 is obtained by cutting a lithium tantalate single crystal material layer at 42°YX, and the thickness can be 2μm. The material of the interdigital transducer 40 can be aluminum metal, and the thickness of the interdigital electrodes in the interdigital transducer 40 can be 160nm. The dielectric layer 30 in the first resonator 110 can be a silicon nitride layer with a thickness of 5nm. The dielectric layer 30 uniformly covers the area where the interdigital transducer 40 is located in the first resonator 110 along a first direction.

[0062] refer to Figure 4 , Figure 4The diagram shows simulation results of the resonator when the dielectric layer 30 includes a silicon nitride layer and the thickness of the dielectric layer 30 varies. Figure 4 The horizontal axis represents frequency (in GHz), and the vertical axis represents admittance (in dB). Figure 4 In the diagram, curve 1 represents the admittance curve of the surface acoustic wave resonator without dielectric layer 30; curves 2, 3, 4, 5, and 6 represent the admittance curves of the first resonator 110 with dielectric layer 30 thicknesses of 5 nm, 10 nm, 15 nm, 20 nm, and 30 nm, respectively. The frequency corresponding to the peak point is the resonant frequency (fs) of the surface acoustic wave resonator, and the frequency corresponding to the valley point is the anti-resonant frequency (fp) of the surface acoustic wave resonator. The relative bandwidth (PZD) of the resonator is defined as: Relative bandwidth is used to represent the relative change in bandwidth.

[0063] refer to Figure 5 and Figure 6 , Figure 5 The relationship between the resonant frequency of the first resonator 110 and the thickness of the dielectric layer 30 is shown. Figure 5 The horizontal axis represents the thickness of the dielectric layer (30 nm), and the vertical axis represents the resonant frequency (fs) in MHz. Figure 6 The relationship between the relative bandwidth of the first resonator 110 and the thickness of the dielectric layer 30 is shown. Figure 6 The horizontal axis represents the dielectric layer thickness (30 nm), and the vertical axis represents the relative bandwidth (%).

[0064] The working principle is as follows: Due to the relatively low dielectric constant of the dielectric layer 30, adding the dielectric layer 30 between the piezoelectric layer 20 and the interdigital transducer 40 reduces the overall relative dielectric constant and relative electromechanical coupling coefficient of the piezoelectric layer 20 and the dielectric layer 30. Since the bandwidth of the surface acoustic wave resonator is directly related to the electromechanical coupling coefficient, the addition of the dielectric layer 30 alters the electromechanical coupling coefficient, thereby changing the bandwidth of the surface acoustic wave resonator. Specifically, the greater the thickness of the dielectric layer 30, the smaller the electromechanical coupling coefficient becomes, and consequently, the smaller the bandwidth of the surface acoustic wave resonator. Figure 5 and Figure 6In this case, Si3N4 indicates that the dielectric layer 30 in the resonator is a high acoustic impedance material layer, and SiO2 indicates that the dielectric layer 30 in the resonator is a low acoustic impedance material layer. When the dielectric layer 30 is a low acoustic impedance material layer, the thickness d of the dielectric layer 30 satisfies 5 nm ≤ d ≤ 30 nm. The dielectric layer 30 causes the relative bandwidth PZD of the resonator to decrease as d increases (ΔPZD ≤ -k1·d, where k1 is a positive coefficient); the dielectric layer 30 causes the resonance frequency fs of the resonator to increase as d increases (Δfs ≥ k3·d, where k3 is a positive coefficient). When the dielectric layer 30 is a high acoustic impedance material layer, the thickness d of the dielectric layer 30 satisfies 5 nm ≤ d ≤ 30 nm. The dielectric layer 30 causes the relative bandwidth PZD of the resonator to decrease as d increases (ΔPZD ≥ -k2·d, where k2 is a positive coefficient and k2 < k1). The dielectric layer 30 causes the resonance frequency fs of the resonator to increase as d increases (Δfs ≤ k4·d, where k4 is a positive coefficient and k3 > k4). For every 1 nm change in thickness d, the bandwidth change of the high impedance material is relatively small, and the frequency offset is relatively small; the bandwidth change of the low impedance material is relatively large, and the frequency offset is relatively large. Therefore, using a high acoustic impedance material can make the influence of thickness change on PZD and fs more gentle, reduce process sensitivity (such as the influence of lithography and etching errors on performance is smaller), and is beneficial to mass production consistency.

[0065] Reference Figure 7 and Figure 8 , Figure 7 is a performance comparison diagram of the surface acoustic wave filter 100 provided by the embodiment of the present specification (wherein, the series resonators 101 are all the first resonators 110, and the parallel resonators 102 are all the second resonators 120) and the surface acoustic wave resonator provided by the comparative example (the filter without inserting the dielectric layer 30 in the resonator). In Figure 7 the surface acoustic wave filter 100 provided by the embodiment of the present specification is represented by a solid line, and the comparative example is represented by a dotted line. Figure 8 is a performance comparison diagram of the right edge of the passband of the surface acoustic wave filter 100 provided by the embodiment of the present specification and the surface acoustic wave resonator provided by the comparative example, that is Figure 8 is Figure 7 a partial enlarged schematic diagram of the right edge of the passband. The topological structures of the surface acoustic wave filter 100 provided by the embodiment of the present specification and the surface acoustic wave filter 100 provided by the comparative example are both as Figure 9 shown. From Figure 7 and Figure 8As can be seen, the surface acoustic wave filter 100 (hereinafter referred to as the embodiment) provided in this specification significantly improves the rectangularity of the right side of the filter. Compared with the comparative example, the transition band of the embodiment is steeper. The rectangularity of the filter is an important indicator for measuring its frequency response to be close to the ideal rectangular characteristic, reflecting the steepness of the transition between the passband and stopband. The higher the rectangularity, the better the selectivity of the filter, and the more effectively it can suppress out-of-band interference. By adding a dielectric layer 30 between the piezoelectric layer 20 and the interdigital transducer 40, the bandwidth of the first structure resonator can be reduced. Through this structural design, precise adjustment of the filter bandwidth is achieved, selectively improving the rectangularity of the right side of the filter, and solving the problem of low rectangularity of the surface acoustic wave resonator.

[0066] Accordingly, this specification also provides a method for fabricating a surface acoustic wave filter 100, comprising: forming a first filter and a second filter; wherein,

[0067] Both the first resonator 110 and the second resonator 120 include: a substrate 10, a piezoelectric layer 20 located on one side of the substrate 10, and an interdigital transducer 40 located on the side of the piezoelectric layer 20 opposite to the substrate 10;

[0068] The first resonator 110 further includes a dielectric layer 30, which is located between the piezoelectric layer 20 and the interdigital transducer 40, and the dielectric layer 30 includes a high acoustic impedance material layer.

[0069] Specifically, in one embodiment, the fabrication process of the surface acoustic wave filter 100 includes:

[0070] Substrate 10 is provided;

[0071] A piezoelectric layer 20 is formed on one side of the substrate 10;

[0072] A dielectric layer 30 is formed on the side of the piezoelectric layer 20 away from the substrate 10. The dielectric layer 30 is selectively removed by photolithography or dry etching, leaving only the dielectric layer 30 covering the area where the piezoelectric layer 20 is located in the first resonator 110.

[0073] Metal electrodes are formed using processes such as magnetron sputtering or electron beam evaporation deposition to form the interdigital transducer 40.

[0074] Exemplary device

[0075] In one embodiment of this specification, an electronic component is also provided, including the surface acoustic wave filter 100 as described in any of the above embodiments.

[0076] The surface acoustic wave (SAW) filter 100 includes a first resonator 110 and a second resonator 120. A dielectric layer 30 is disposed between the piezoelectric layer 20 and the interdigital transducer 40 of the first resonator 110. This allows for bandwidth adjustment of the first resonator 110 by adjusting the thickness of the dielectric layer 30, selectively improving the rectangularity of the left, right, or both sides of the SAW filter 100, thus achieving the goal of improving the rectangularity of the SAW filter 100. Furthermore, the dielectric layer 30 includes a high acoustic impedance material layer, based on the acoustic impedance formula: Z = ρ × v (material density ρ × sound velocity v) and the reflection coefficient... It is known that the greater the difference in acoustic impedance between the two layers (e.g., piezoelectric layer 20 and dielectric layer 30), the stronger the reflection, and the higher the energy loss. When a dielectric layer 30 is inserted between the interdigital transducer 40 and the piezoelectric layer 20, the degree of matching between the acoustic impedance of the dielectric layer 30 and the acoustic impedance of the piezoelectric layer 20 determines the propagation loss and energy coupling efficiency of the surface acoustic wave. Because the high acoustic impedance material layer is closer to the acoustic impedance of the piezoelectric layer 20, it reduces interface reflection and energy loss. The thickness variation has a smaller impact on the electromechanical coupling coefficient and propagation path, resulting in smaller bandwidth and frequency shift. That is, under the same thickness variation, the bandwidth and frequency shift of the high acoustic impedance material layer are smaller than those of the low acoustic impedance material layer. Therefore, including a high acoustic impedance material layer in the dielectric layer 30 can reduce the device's process sensitivity and mitigate the adverse effects of process errors on the designed target bandwidth.

[0077] The electronic components may be, but are not limited to, filters, duplexers, delay lines, frequency discriminators, or modulators.

[0078] This specification provides an embodiment of an electronic device including a transceiver and a processor. Specifically, the transceiver is used to receive or transmit signals. The transceiver includes the electronic components provided in this application. The processor is used to perform signal processing on the signals. The processor is coupled to the transceiver.

[0079] Electronic devices can be terminal devices, also known as user equipment (UE), access terminals, user units, user stations, mobile stations, mobile stations, remote stations, remote terminals, mobile devices, user terminals, terminals, wireless communication equipment, user agents, or user devices. As an example and not a limitation, terminal devices can be mobile phones, tablets, computers with wireless transceiver capabilities, virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical care, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, etc.

[0080] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] The embodiments described above are merely illustrative of several implementations of this specification, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the solutions provided in this specification. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this specification, and these all fall within the scope of protection of this specification. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A surface acoustic wave filter, characterized in that, include: First resonator and second resonator; wherein... Both the first resonator and the second resonator include: a substrate, a piezoelectric layer located on one side of the substrate, and an interdigital transducer located on the side of the piezoelectric layer opposite to the substrate; The first resonator further includes a dielectric layer located between the piezoelectric layer and the interdigital transducer, the dielectric layer comprising a high acoustic impedance material layer.

2. The surface acoustic wave filter according to claim 1, characterized in that, The thickness of the dielectric layer ranges from 5 nm to 30 nm.

3. The surface acoustic wave filter according to claim 1, characterized in that, The piezoelectric layer of the first resonator and the piezoelectric layer of the second resonator are the same piezoelectric layer.

4. The surface acoustic wave filter according to claim 1, characterized in that, The high acoustic impedance material layer includes a material layer with an acoustic impedance greater than 30 MRayl.

5. The surface acoustic wave filter according to claim 1, characterized in that, The high acoustic impedance material layer includes a material layer with an acoustic impedance greater than 45 M ayl.

6. The surface acoustic wave filter according to any one of claims 1 to 5, characterized in that, The high acoustic impedance material layer includes at least one of the following: a platinum metal layer, a tungsten metal layer, a tantalum metal layer, an iridium metal layer, a rhenium metal layer, a silicon nitride layer, and a molybdenum metal layer.

7. The surface acoustic wave filter according to any one of claims 1 to 5, characterized in that, Both the first resonator and the second resonator further include: a reflective grating; The reflective grating is located on both sides of the interdigital transducer in a first direction, which intersects the extension direction of the interdigital electrodes in the interdigital transducer.

8. The surface acoustic wave filter according to any one of claims 1 to 5, characterized in that, Both the first resonator and the second resonator further include: a temperature compensation layer, a protective layer, and a low-velocity sound layer; wherein, The temperature compensation layer is located on the side of the interdigital transducer away from the substrate, and the protective layer is located on the side of the temperature compensation layer away from the substrate. The low-velocity layer is located between the substrate and the piezoelectric layer.

9. An electronic component, characterized in that, Includes one or more surface acoustic wave filters as described in any one of claims 1 to 8.

10. An electronic device, characterized in that, include: A transceiver for receiving or transmitting signals, the transceiver comprising the electronic components as described in claim 9; A processor for processing the signal, wherein the processor is coupled to the transceiver.

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