Electrode, piezoelectric device and its design method, piezoelectric filter, electronic device

Abstract

The present application provides an electrode, a piezoelectric device and its design method, a piezoelectric filter, and an electronic device. The piezoelectric device includes: a first electrode, a piezoelectric layer, a second electrode, an acoustic mirror, and a substrate stacked in sequence; an overlapping region of the first electrode, the piezoelectric layer, the second electrode, and the acoustic mirror in the stacking direction constitutes an effective region of the piezoelectric device; the effective region includes a first elliptical region and a second elliptical region; the first elliptical region includes a major axis side, and a first elliptical arc corresponding to the major axis side and a first minor axis; the second elliptical region includes the major axis side, and a second elliptical arc corresponding to the major axis side and a second minor axis; the first elliptical arc and the second elliptical arc are respectively connected at two end points of the major axis side; the first elliptical region and the second elliptical region are adjacent to each other in the same plane with the major axis side as the boundary; the first minor axis and the second minor axis are not of equal length.

Description

Technical Field

[0001] The present application relates to the technical field of piezoelectric devices, and particularly to an electrode, a piezoelectric device and its design method, a piezoelectric filter, and an electronic device. Background Art

[0002] As the mobile communication technology enters the 5G era, a large number of 5G mobile terminals and base stations are widely deployed worldwide. In addition to inheriting the communication frequency bands of the previous generation 4G and 4G-LTE in the range of 700 MHz - 2.7 GHz, 5G technology also expands applications above 3 GHz, such as N77, N78, N79, with the highest frequency reaching 5 GHz. At the same time, wireless local area network (WLAN) technology, mainly represented by Wi-Fi, is also constantly evolving. Wi-Fi 6 / 6E has entered people's daily lives, and they expand applications above 6 GHz on the basis of the traditional 2.4 GHz and 5 GHz frequency bands (collectively referred to as Sub 6 GHz). Most current mobile communication terminals support wireless access to both of these technologies simultaneously. Multi-mode and multi-band have gradually become general technical requirements. Among them, the radio frequency circuit responsible for the air interface is becoming increasingly complex. However, mobile terminals also need to take into account the requirement of miniaturization at the same time. Therefore, the market's demand for high-performance and miniaturized radio frequency filtering devices is becoming more urgent.

[0003] Currently, the filtering devices that can meet such requirements are mainly piezoelectric acoustic wave filters. The resonators that make up such acoustic wave filters mainly include bulk acoustic wave (BAW) resonators and surface acoustic wave (SAW) resonators. Among them, bulk acoustic wave filters have advantages such as higher application frequencies, lower insertion losses, faster roll-off edges, greater power capacities, and anti-static characteristics. Therefore, they are more suitable for the needs of high-frequency scenarios.

[0004] The performance of BAW resonators is mainly affected by lateral resonance. When the resonance frequency of a certain mode of lateral resonance is exactly near the longitudinal main resonance mode (the resonance mode corresponding to the resonance frequency), the energy superposition generated by lateral resonance may be near the main resonance frequency. The impedance spikes generated due to lateral resonance will affect the insertion loss of the bulk acoustic wave filter and deteriorate the device performance.

[0005] In related technologies, the shape of the effective area of the BAW resonator is usually set to an ellipse to increase the length of the lateral resonance distances at each edge point and make them as different as possible, so as to improve the device performance as much as possible. However, there may still be points with similar reflection paths in some adjacent areas on the arc edge of the ellipse, forming energy superposition, and then generating impedance spikes, reducing the device performance. Summary of the Invention

[0006] The present application provides an electrode, a piezoelectric device and its design method, a piezoelectric filter, and an electronic device, which can improve the lateral resonance distance by destroying the symmetry of the elliptical effective region, disperse the edge points of similar reflection paths, and improve the device performance.

[0007] In a first aspect, the present application provides a piezoelectric device, including: a first electrode, a piezoelectric layer, a second electrode, an acoustic mirror, and a substrate stacked in sequence;

[0008] The overlapping regions of the first electrode, the piezoelectric layer, the second electrode, and the acoustic mirror in the stacking direction form the effective region of the piezoelectric device;

[0009] The effective region includes a first elliptical region and a second elliptical region;

[0010] The first elliptical region includes a long axis side and a first elliptical arc corresponding to the long axis side and a first short axis; the second elliptical region includes the long axis side and a second elliptical arc corresponding to the long axis side and a second short axis; the first elliptical arc and the second elliptical arc are respectively connected at two end points of the long axis side;

[0011] Wherein, the first elliptical region and the second elliptical region are adjacent to each other in the same plane with the long axis side as the boundary; the first short axis and the second short axis are not of equal length.

[0012] Optionally, the first elliptical arc is a semi-elliptical arc corresponding to the long axis side and the first short axis;

[0013] The second elliptical arc is a semi-elliptical arc corresponding to the long axis side and the second short axis.

[0014] Optionally, it further includes: an input end and an output end;

[0015] The input end is connected to the first electrode, and the output end is connected to the second electrode;

[0016] The input end and the output end are respectively arranged at two end points of the long axis side.

[0017] Optionally, the first elliptical region further includes a first truncated edge, and the first truncated edge is connected to the first elliptical arc; the first truncated edge is not parallel to the long axis side; the second elliptical arc is a semi-elliptical arc corresponding to the long axis side and the second short axis;

[0018] Or,

[0019] The second elliptical region further includes a second truncated edge, and the second truncated edge is connected to the second elliptical arc; the second truncated edge is not parallel to the long axis side; the first elliptical arc is a semi-elliptical arc corresponding to the long axis side and the first short axis.

[0020] Optionally, the first elliptical region further includes a first truncated edge, and the first truncated edge is connected to the first elliptical arc;

[0021] The second elliptical region further includes a second truncated edge, and the second truncated edge is connected to the second elliptical arc;

[0022] Wherein, the first truncated edge and the second truncated edge are not parallel.

[0023] In a second aspect, the present application provides a piezoelectric device, wherein the first elliptical arc in the piezoelectric device according to any one of the first aspect is replaced with an inscribed broken line of the first elliptical arc; and the second elliptical arc is replaced with an inscribed broken line of the second elliptical arc.

[0024] In a third aspect, the present application provides an electrode of a piezoelectric device, and the electrode is used as the first electrode and / or the second electrode of the piezoelectric device according to the first aspect to form the effective region.

[0025] In a fourth aspect, the present application provides a design method of a piezoelectric device. The piezoelectric device includes a first electrode, a piezoelectric layer, a second electrode, an acoustic mirror, and a substrate stacked in sequence; an overlapping region of the first electrode, the piezoelectric layer, the second electrode, and the acoustic mirror in the stacking direction constitutes the effective region of the piezoelectric device; the effective region includes a first elliptical region and a second elliptical region; the first elliptical region includes a major axis side and an inscribed broken line of a first elliptical arc corresponding to the major axis side and a first minor axis; the second elliptical region includes the major axis side and an inscribed broken line of a second elliptical arc corresponding to the major axis side and a second minor axis; the inscribed broken lines of the first elliptical arc and the second elliptical arc are respectively connected to two end points of the major axis side; wherein, the first elliptical region and the second elliptical region are adjacent to each other in the same plane with the major axis side as the boundary; the first minor axis and the second minor axis are not of equal length; the method includes:

[0026] Determine the first ellipse and the second ellipse;

[0027] Determine the first elliptical arc from the first ellipse;

[0028] Determine the second elliptical arc from the second ellipse;

[0029] Select a corresponding number of points from the first ellipse and the second ellipse at a set step angle;

[0030] Select the points located on the first elliptical arc and the second elliptical arc from the selected corresponding number of points as the in-points;

[0031] Connect the inner contact points, the endpoints of the first elliptical arc, and the endpoints of the second elliptical arc in sequence to form the inscribed broken line of the first elliptical arc and the inscribed broken line of the second elliptical arc, so as to constitute the effective area.

[0032] In a fifth aspect, the present application provides a piezoelectric filter, including: the piezoelectric device according to any one of the first aspect or any one of the second aspect.

[0033] In a sixth aspect, the present application provides an electronic device, including: the piezoelectric filter according to the fifth aspect.

[0034] In a seventh aspect, the present application provides a design device for a piezoelectric device, including:

[0035] An elliptical determination module for determining a first ellipse and a second ellipse;

[0036] An elliptical arc selection module for determining a first elliptical arc from the first ellipse; and determining a second elliptical arc from the second ellipse;

[0037] An inner contact point determination module for selecting a corresponding number of points from the first ellipse and the second ellipse at a set step angle; and selecting the points located on the first elliptical arc and the second elliptical arc from the selected corresponding number of points as inner contact points;

[0038] An effective area adjustment module for connecting the inner contact points, the endpoints of the first elliptical arc, and the endpoints of the second elliptical arc in sequence to form the inscribed broken line of the first elliptical arc and the inscribed broken line of the second elliptical arc, so as to constitute the effective area.

[0039] In an eighth aspect, the present application provides a design device for a piezoelectric device, including: a memory and a processor; a computer program capable of being loaded and executed by the processor for the design method of the fourth aspect is stored on the memory.

[0040] In a ninth aspect, the present application provides a computer-readable storage medium storing a computer program capable of being loaded and executed by the processor for the design method of the fourth aspect.

[0041] The present application provides an electrode, a piezoelectric device and its design method, a piezoelectric filter, and an electronic device. The effective area of the piezoelectric device is divided into two sub-areas, and the shape of each sub-area is a part of an ellipse. The ellipses corresponding to the two sub-areas have the same major axis and different minor axes. In this way, a composite ellipse is formed. Compared with the ellipse in the prior art, the symmetry based on the major axis is eliminated, the difference in the relative positions of each point at the edge of the effective area is increased, the edge points of similar reflection paths are dispersed, so as to eliminate as much as possible the problem of similar resonance paths of multiple points that may exist on the elliptical arc, and the performance of the device is improved. Brief Description of the Drawings

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application or 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 some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0043] Figure 1 Schematic diagram of an existing elliptical effective area provided by an embodiment of the present application;

[0044] Figure 2 For an embodiment of the present application to perform Figure 1 Schematic diagram of the result of resonance distance analysis on the edge sampling points of the effective area;

[0045] Figure 3 For an embodiment of the present application Figure 1 Schematic diagram of the resonance path of a starting point in;

[0046] Figure 4 For an embodiment of the present application Figure 1 Schematic diagram of the resonance path of another starting point in;

[0047] Figure 5 Schematic diagram of a composite elliptical effective area provided by an embodiment of the present application;

[0048] Figure 6 For an embodiment of the present application Figure 5 Schematic diagram of the setting position of the composite elliptical edge sampling points shown in;

[0049] Figure 7 For an embodiment of the present application to perform Figure 6 Statistical chart of the transverse resonance distance distribution of each sampling point in;

[0050] Figure 8 For an embodiment of the present application Figure 6 Schematic diagram of the resonance path of a starting point in;

[0051] Figure 9 For an embodiment of the present application Figure 6 Schematic diagram of the resonance path of another starting point in;

[0052] Figure 10 For an embodiment of the present application Figure 6 Schematic diagram of the resonance path of another starting point in;

[0053] Figure 11Provided by an embodiment of the present application Figure 6 Schematic diagram of the resonance path of another starting point in

[0054] Figure 12 Provided by an embodiment of the present application Figure 6 Schematic diagram of the resonance path of another starting point in

[0055] Figure 13 Provided by an embodiment of the present application Figure 6 Schematic diagram of the resonance path of another starting point in

[0056] Figure 14 A resonator provided by an embodiment of the present application with a Figure 5 Schematic diagram of the structure of a resonator with the shown composite ellipse as the effective area;

[0057] Figure 15 Schematic diagram of a composite elliptical effective area with truncated edges provided by an embodiment of the present application;

[0058] Figure 16 Schematic diagram of the distribution of sampling points in a composite elliptical effective area with truncated edges provided by an embodiment of the present application;

[0059] Figure 17 Provided by an embodiment of the present application Figure 16 Schematic diagram of the resonance path of one starting point in

[0060] Figure 18 Provided by an embodiment of the present application Figure 16 Schematic diagram of the resonance path of another starting point in

[0061] Figure 19 Provided by an embodiment of the present application Figure 16 Schematic diagram of the resonance path of another starting point in

[0062] Figure 20 Provided by an embodiment of the present application for Figure 6 Statistical chart of the transverse resonance distance distribution of each sampling point in

[0063] Figure 21 A resonator provided by an embodiment of the present application with a Figure 16 Schematic diagram of the structure of a resonator with the shown composite ellipse as the effective area;

[0064] Figure 22 Provided by an embodiment of the present application Figure 21 Cross-sectional view of the shown resonator along the transverse dotted line position;

[0065] Figure 23Another schematic diagram of a composite elliptical effective area with truncated edges provided by an embodiment of the present application;

[0066] Figure 24 For an embodiment of the present application, Figure 23 Statistical chart of the lateral resonance distance distribution of some sampling points of the composite ellipse in

[0067] Figure 25 Another schematic diagram of a composite elliptical effective area with truncated edges provided by an embodiment of the present application;

[0068] Figure 26 For an embodiment of the present application, Figure 25 Statistical chart of the lateral resonance distance distribution of some sampling points of the composite ellipse in

[0069] Figure 27 Another schematic diagram of a composite elliptical effective area with truncated edges provided by an embodiment of the present application;

[0070] Figure 28 For an embodiment of the present application, Figure 16 Schematic diagram of the ellipse arc folding of the composite ellipse in

[0071] Figure 29 For an embodiment of the present application, Figure 28 Statistical chart of the lateral resonance distance distribution of some sampling points of the composite ellipse in

[0072] Figure 30 Schematic diagram of the structure of a piezoelectric filter provided by an embodiment of the present application;

[0073] Figure 31 Schematic diagram of the structure of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0074] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0075] In addition, the term "and / or" in this text is merely a correlative relationship describing associated objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this text generally represents an "or" relationship between the front and back associated objects unless otherwise specified.

[0076] The embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings of the specification. For the convenience of comparison and description, the area of the effective region adopted in each embodiment of the present application is 10,000 μm 2 .

[0077] In the prior art, the shape of the effective region of a BAW resonator is usually set to be elliptical to achieve the purpose of increasing the length of the lateral resonance distance at each point on the edge and making them as different as possible. However, this method has certain disadvantages. The characteristics of the ellipse being symmetric about the major axis and the minor axis will result in the lateral resonance distance of the curves in the four quadrants not being long enough and partial regions being highly overlapped.

[0078] Figure 1 is an implementation method of an elliptical resonator in the prior art. The ellipse in the figure is the edge of the effective region of the resonator. The ellipse has an axisymmetric characteristic, and the resonance paths of two points symmetric about the axis of symmetry are the same. Therefore, in this embodiment, the arc edge of the right half of the minor axis of the ellipse is taken as an example for analysis. On this arc edge, a series of sampling points are set at intervals of 3 μm as the starting points for lateral resonance analysis. Among them, the point located at the lower vertex is numbered 101, and the remaining points are numbered in counterclockwise order, with a total of 60 points. Taking these points as starting points respectively, the lateral resonance paths are calculated, and the results are as shown in the line chart in Figure 2 . Figure 2 In, the lateral resonance distance is shown in logarithmic coordinates and is generally distributed in the range of 850 μm to 50,000 μm, and the median value can reach ***********12295.1 μm.

[0079] However, the ellipse is axisymmetric about both the major axis and the minor axis, and the elliptical arc also has a certain centripetal characteristic similar to a circle. Therefore, the lateral resonance paths formed by the points in some regions cannot completely cover the effective region of the resonator, which all lead to the shortening of the lateral resonance distance and the concentration of the distribution, resulting in the deterioration of performance. Especially in the region closer to the center of the ellipse (near the minor semi-axis), the resonance paths are similar, such as the starting point No. 102 shown in Figure 3 and Figure 4The starting point No. 104 as shown. Through analysis, it is found that this is because the curvature of the position near the minor axis on the elliptical arc is small, and the shorter arc can be approximated as a small straight line segment. In this way, two shorter arcs that are centrosymmetric about the center of the ellipse are close to a pair of parallel lines. The sound waves emitted on this approximately straight arc will be reflected back on the approximately parallel arc on the opposite side. In this way, the resonant path of the sound waves will be restricted to a relatively narrow range along the major axis direction, forming a "beam" similar to Figure 3 and Figure 4 as shown. This results in the resonant paths of the points on this approximately straight arc being similar, and the resonant energy will also be superimposed at the same frequency point, forming impedance spikes.

[0080] Therefore, how to design the shape of a resonator so that its lateral resonant distance is as large as possible and the distribution at each edge point is as dispersed as possible has become an urgent problem to be solved in the design of piezoelectric filters.

[0081] Based on this, the present application provides an electrode, a piezoelectric device and its design method, a piezoelectric filter, and an electronic device, which break the symmetry of the ellipse based on the major axis to eliminate the approximately parallel lines existing in the ellipse, so as to reduce the superposition of resonant energy and improve the performance of the resonator.

[0082] In some embodiments, a piezoelectric device provided by the present application includes: a first electrode, a piezoelectric layer, a second electrode, an acoustic mirror, and a substrate stacked in sequence. The overlapping regions of the first electrode, the piezoelectric layer, the second electrode, and the acoustic mirror in the stacking direction form the effective region of the piezoelectric device. The effective region can be divided into two sub-regions, and the shape of each sub-region is a part of an ellipse. For distinction, in the present application, they are respectively referred to as the first elliptical region and the second elliptical region. The two sub-regions have a common side, which is also the major axis of the corresponding ellipse, and is referred to as the major axis side in the present application. The minor axis of the ellipse corresponding to the first elliptical region is called the first minor axis, and the minor axis of the ellipse corresponding to the second elliptical region is called the second minor axis, and the first minor axis and the second minor axis are not of equal length.

[0083] Except for the major axis side, the first elliptical region further includes a first elliptical arc corresponding to the major axis side and the first minor axis, that is, the elliptical arc on the ellipse corresponding to the first elliptical region; the second elliptical region further includes a second elliptical arc corresponding to the major axis side and the second minor axis, that is, the elliptical arc on the ellipse corresponding to the second elliptical region.

[0084] It should be noted that the "major axis side" in the present application is a feature used to illustrate the relationship between the two sub-regions in the effective region, and it actually exists within the effective region range, rather than the boundary of the effective region.

[0085] In addition, the first electrode and the second electrode are only used to distinguish two different electrodes in the piezoelectric device. When one of them corresponds to the upper electrode, the other is the lower electrode. Which one is the upper electrode can vary according to the actual scenario and is not restricted in this application.

[0086] The first elliptical arc and the second elliptical arc are respectively taken from the arcs of the corresponding ellipses, but the number of them is not restricted.

[0087] In some embodiments, the first elliptical arc and the second elliptical arc respectively include a section of arc taken from the corresponding ellipse. Moreover, the two ends of the first elliptical arc are respectively connected to the two ends of the major axis side, forming the first elliptical region (half an ellipse); the two ends of the second elliptical arc are respectively connected to the two ends of the major axis side, forming the second elliptical region (half an ellipse). The first elliptical arc and the second elliptical arc are connected to jointly form the boundary of the effective region. The specific shape can be referred to Figure 5 .

[0088] As Figure 5 shown, for the ellipse 51, with the midpoint 511 of the major axis as the center, the straight line 512 as the major axis, and the straight line 513 as the minor axis; for the ellipse 52, with the midpoint 511 of the major axis as the center, the straight line 512 as the major axis, and the straight line 523 as the minor axis.

[0089] Taking the major axis side 512 as the boundary, the upper half of the ellipse 51 is used as the first elliptical region, and the lower half of the ellipse 52 is used as the second elliptical region, jointly forming a composite ellipse (effective region). The upper half elliptical arc 514 of the ellipse 51 is used as the first elliptical arc, and the lower half elliptical arc 524 of the ellipse 52 is used as the second elliptical arc, jointly forming the boundary of the composite ellipse (effective region), as shown by the solid line in the figure.

[0090] The joint point of the first elliptical arc 514 and the second elliptical arc 524 is the intersection point of them and the major axis side, and is also the end point of the major axis side. The one on the left side of the center is the left joint point 515, and the one on the right side of the center is the right joint point 516. The intersection point of the first elliptical arc 514 and the minor axis 513 is the upper vertex 517 of the composite ellipse, and the intersection point of the second elliptical arc 524 and the minor axis 523 is the lower vertex 518 of the composite ellipse.

[0091] For the convenience of description, in the embodiments of this application, the variable a will be used to represent the length of the major semi-axis of the two ellipses, the variable b1 will be used to represent the length of the minor semi-axis of the upper half ellipse, and b2 will be used to represent the length of the minor semi-axis of the lower half ellipse. As can be seen from Figure 5 this, in this embodiment, the minor axis 513 is slightly longer than the minor axis 523. Therefore, a > b1 > b2. It can be understood that if the length relationship is reversed, it is equivalent to flipping the current composite ellipse up and down along the major axis, and it is still the same figure, so all the analysis conclusions obtained remain unchanged.

[0092] Obviously, Figure 5 the shown composite ellipse is a figure symmetric about the short axis and asymmetric about the long axis. Therefore, if this composite ellipse is used as the shape of the effective area of the resonator, only the part on one side of the short axis of symmetry needs to be analyzed. The normal lines at the positions of the upper vertex and the lower vertex point to each other respectively, and the transverse resonance distance starting from these two points is 2(b1 + b2). The normal lines at the positions of the left joint point and the right joint point also point to each other respectively, and the transverse resonance distance starting from these two points is 4a. When analyzing the transverse resonance distance, these special positions can be temporarily ignored, and only edge sampling points are set on the elliptical arc on the right side of the short axis as the starting points.

[0093] Figure 6 Shows the positions of the sampling points set on the composite ellipse. Set the value of the length a of the semi-major axis to 70um, the value of the length b1 of the semi-minor axis of the upper semi-ellipse to 49.7um, the value of the length b2 of the semi-minor axis of the lower semi-ellipse to 41.3um, and the area of the entire composite ellipse is approximately 10000um 2 .

[0094] In some implementations, the sampling points can be selected by the following method.

[0095] 1) Set the step angle: δ = 3;

[0096] 2) Construct a coordinate system with the center as the origin, and calculate the number of sampling points in one quadrant: N = 90 / δ = 30;

[0097] 3) Draw a ray from the center to the right as the point-taking line, and set the angle between the point-taking line and the long axis to β;

[0098] 4) Let β be equal to (-N - 0.5 + n)δ respectively, where n = 1, 2,..., 2N, so that a total of 2N point-taking lines are obtained;

[0099] 5) Set the intersection points of these point-taking lines and the composite ellipse as the starting points, and number them as n. The one closest to the lower vertex is the 1st starting point 601, and the one closest to the upper vertex is the 2Nth starting point 660.

[0100] Figure 7 The transverse resonance distance distribution of all sampling points is shown in the form of a line graph. The resonance distances of each point are generally distributed in the range of 560μm to 335000μm, and the median value reaches 22785.3μm. Comparing Figure 2 It can be seen that Figure 5 the composite ellipse of Figure 1The oval shape significantly increases the path length of the transverse resonance and is dispersed at the edge of the entire effective area, thereby improving the performance of the resonator. This is mainly because the characteristic of the overall shape being symmetric about the long axis is eliminated.

[0101] Figure 8 shows Figure 6 the transverse resonance path distribution of the starting point 612 at No. 12 in []. Although the transverse resonance path at this point is relatively concentrated, the number of reflections is large, and the path length reaches 47622.1 μm. Figure 9 shows Figure 6 the transverse resonance path distribution of the starting point 625 at No. 25 in []. It can be seen that the transverse resonance path at this point basically fills the inside of the shape, and the path length reaches 55552.5 μm.

[0102] However, the characteristic of being symmetric about the short axis still has a certain influence. As a result, there are still cases where the transverse resonance distance at certain specific points is relatively small. As Figure 10 shown, Figure 6 the transverse resonance path length of the starting point 617 at No. 17 in [] is only 560.7 μm. Moreover, near the upper vertex and the lower vertex, there is still a relatively small area where the transverse resonance distances of the sampling points are very close or even equal. As Figure 11 shown, Figure 6 the transverse resonance path length of the starting point 601 at No. 1 in [] is 2191.8 μm. As Figure 12 shown, Figure 6 the transverse resonance path length of the starting point 602 at No. 2 in [] is 2557 μm. As Figure 13 shown, Figure 6 the transverse resonance path length of the starting point 657 at No. 57 in [] is 2557 μm. Comparing Figure 3 , Figure 4 it can be seen that for points at similar positions, the similarity of the resonance paths in the composite oval is lower than that in the oval, which can achieve a certain performance optimization effect, but still has a certain impact on the resonator performance. Through a large number of experiments, it is found that this situation is more obvious when the ratio of a to b1 (or b2) is larger (the ellipse is flatter). On the contrary, in the region near the left and right joint points, the values of the transverse resonance distances are significantly larger than those of the points in the region near the upper and lower vertices, as shown in the distribution diagrams of Figure 8 , Figure 9 .

[0103] In some embodiments, in view of the above situation, the electrical signal can be input into the resonator from near the left and right joint points. That is, the input end and the output end are arranged on the left and right sides of the composite ellipse, as Figure 14As shown in the figure. In the figure, the shapes of the first electrode 141 and the second electrode 142 are the same as the shape of the effective area, both being composite ellipses. The input terminal 143 is connected to the endpoint of the long axis side of the first electrode 141 adjacent to the left side of the effective area, and the output terminal 144 is connected to the endpoint of the long axis side of the second electrode 142 adjacent to the right side of the effective area.

[0104] It should be noted that the "left" and "right" mentioned in this embodiment are both based on Figure 14 the shown composite ellipse graph. Corresponding to the description in the above embodiment, the first electrode in this embodiment can be the upper electrode or the lower electrode, specifically subject to the actual scenario design requirements, and there is no limitation in this embodiment.

[0105] At this time, the flow direction of the electrical signal is the direction shown by the solid line arrow in the figure, parallel to the long axis direction. The starting points of the transverse resonance mostly gather near the left and right combination points, the resonance distance is relatively long, and the resonance path differences at adjacent points are relatively large, which can reduce the burrs and improve the performance.

[0106] However, in this setting scenario, the transmission distance of the electrical signal is relatively long, and the width of the transmission electrode is relatively narrow (as shown by the dashed line arrow in the figure). According to Ohm's law, these will all increase the resistance, thereby increasing the electrical loss during the transmission process, increasing the overall insertion loss of the filter, and reducing the performance.

[0107] To solve this problem, on the basis of Figure 5 the composite ellipse, some changes are made, such as Figure 15 shown in the figure, where the components the same as Figure 5 are omitted from the corresponding marking description.

[0108] First, select a point 1511 on the short axis 513 of the composite ellipse as the upper cut-off point, and the position of the upper cut-off point is between the upper vertex and the center point. The length between the upper cut-off point and the center point is called the upper intercept, denoted as d1. Draw a straight line through the upper cut-off point, and the angle 1512 between this straight line and the horizontal direction is called the upper inclination angle, denoted as α1. Appropriately select the values of d1 and α1, so that this straight line intersects the upper half ellipse at two points. The intersection point in the first quadrant is called the upper right vertex 1513, and the intersection point in the second quadrant is called the upper left vertex 1514. The straight line segment between the upper right vertex and the upper left vertex is called the upper cut-off edge 1515. When the upper right vertex is higher than the upper left vertex, α1>0; conversely, when the upper left vertex is higher than the upper right vertex, α1<0.

[0109] Similarly, select a point 1521 on the minor axis 523 of the composite ellipse as the lower cut-off point, and the position of the lower cut-off point is between the lower vertex and the center point. The length between the lower cut-off point and the center point is called the lower intercept, denoted as d2. Draw a straight line through the lower cut-off point, and the angle 1522 between this straight line and the horizontal direction is called the lower inclination angle, denoted as α2. By appropriately selecting the values of d2 and α2, this straight line can intersect the lower half ellipse at two points. The intersection point in the third quadrant is called the lower left vertex 1523, and the intersection point in the fourth quadrant is called the lower right vertex 1524. The straight line segment between the lower left vertex and the lower right vertex is called the lower cut-off edge 1525. When the lower right vertex is higher than the lower left vertex, α2>0; conversely, when the lower left vertex is higher than the lower right vertex, α2<0. In this way, the upper cut-off edge 1515, the lower cut-off edge 1525, and the arc of the composite ellipse between them form the shape of a new effective area.

[0110] In this embodiment, the first elliptical arc and the second elliptical arc respectively include two arc segments taken from the corresponding ellipse. The upper cut-off edge 1515 is the first cut-off edge, and the two arc segments between the first cut-off edge and the major axis edge are the first elliptical arc. The first cut-off edge, the first elliptical arc, and the major axis edge are connected to enclose the first elliptical area. The lower cut-off edge 1525 is the second cut-off edge, and the two arc segments between the second cut-off edge and the major axis edge are the second elliptical arc. The second cut-off edge, the second elliptical arc, and the major axis edge are connected to enclose the second elliptical area.

[0111] The shape of the effective area provided in this embodiment is equivalent to cutting off the areas near the upper vertex and the lower vertex of the composite ellipse in the previous embodiment with two edges (the upper cut-off edge and the lower cut-off edge), further eliminating the characteristic of the composite ellipse being symmetric about the minor axis. Furthermore, the problem of the short lateral resonance distance of the composite ellipse in this area is avoided.

[0112] In some preferred implementation manners, in order to make the lateral resonance distance of the sound waves excited by the upper cut-off edge and the lower cut-off edge larger, these two edges (the upper cut-off edge and the lower cut-off edge) are not parallel.

[0113] In some implementation manners, the slopes of the two cut-off edges can be one positive and one negative. That is, α1α2<0. As Figure 16 shown. Figure 16 is a schematic diagram of the shape of an effective area constructed by the above method. Among them, the length a of the major semi-axis of the composite ellipse is 73.9um, the length b1 of the minor semi-axis of the upper half ellipse is 54.7um, the length b2 of the minor semi-axis of the lower half ellipse is 42.1um, the upper intercept d1 is 43.8um, the lower intercept d2 is 33.7um, the upper inclination angle α1 is 5 degrees, and the lower inclination angle α2 is -5 degrees.

[0114] To analyze the transverse resonance distance of the input signal on the straight edge, 29 starting points are set at intervals of 3 μm on the upper and lower edges respectively, for a total of 58 starting points, as Figure 16 shown. The leftmost point on the upper edge is the 1st starting point 1601, the leftmost point on the lower edge is the 30th starting point 1630, and the rightmost point is the 58th starting point 1658.

[0115] Figure 17 , Figure 18 , Figure 19 are schematic diagrams of the transverse resonance path distributions of the 1st starting point 1601, the 32nd starting point 1632, and the 45th starting point 1645 respectively. Among them, the transverse resonance path length of the 1st starting point 1601 is 22191.6 μm, the transverse resonance path length of the 32nd starting point 1632 is 39431.6 μm, and the transverse resonance path length of the 45th starting point 1645 is 4724.5 μm. It can also be seen from the figure that after setting the straight edges on the upper and lower sides of the composite ellipse, the transverse resonance paths of the sound waves starting from the straight edges almost cover most of the effective area of the resonator.

[0116] Figure 20 is Figure 16 the distribution diagram of the transverse resonance distances of each sampling point in Figure 7 . The resonance distance distribution of each point is in the range of 1500 μm to 107000 μm, and the median value is 23772.9 μm. Compared with the transverse resonance distance distribution starting from the starting points near the upper and lower vertices in Figure 7 , the transverse resonance distance on the straight edge in this embodiment is longer and the distribution is more dispersed, which can further improve the device performance.

[0117] Figure 21 is a schematic diagram of a resonator having the shape of the effective area shown in Figure 16 . Figure 22 Shows the cross-sectional view of the resonator along the transverse dotted line position shown in Figure 21 . As shown in Figure 21 , Figure 22 , in this embodiment, the resonator is formed by connecting two piezoelectric devices 211 and 212. The electrode shapes of the piezoelectric devices 211 and 212 are the same as the shape of the effective area, both being truncated composite ellipses.

[0118] The lower edge of the first electrode 2111 of the piezoelectric device 211 is connected to the upper edge of the first electrode 2121 of the piezoelectric device 212 through the connecting member 213 and is arranged on the piezoelectric layer 217. The input end 214 of the resonator is connected to the upper edge of the second electrode 2112 of the piezoelectric device 211, and the output end 215 is connected to the lower edge of the second electrode 2122 of the piezoelectric device 212 and is arranged on the substrate 216.

[0119] In this embodiment, the two straight sides of the resonator serve as the input end and the output end of the electrical signal respectively, and the lateral resonance distance is relatively long. This reduces the impedance spikes caused by the short lateral resonance distance and the resulting energy superposition in the above embodiment, thereby improving the performance of the resonator. Moreover, the flow direction of the electrical signal is along the short-axis direction (the direction of the solid arrow in the figure), the transmission distance is relatively short, and the electrode width for transmission is relatively wide, as Figure 21 shown by the dashed line in

[0120] According to Ohm's law, all of these will reduce the electrode resistance, thereby reducing the electrical loss during transmission, reducing the overall insertion loss of the filter, and improving the performance. Figure 23 shown. Figure 23 FIG.

[0121] is a schematic diagram of another effective area shape constructed using the above method. Among them, the length a of the major semi-axis of the composite ellipse is 68.9 um, the length b1 of the minor semi-axis of the upper semi-ellipse is 63.6 um, the length b2 of the minor semi-axis of the lower semi-ellipse is 42.4 um, the upper intercept d1 is 47.7 um, the lower intercept d2 is 33.9 um, the upper inclination angle α1 is 3 degrees, and the lower inclination angle α2 is 0 degree, that is, the lower truncated side is in the horizontal direction parallel to the long axis. Figure 23 In a sampling manner similar to the above embodiment, 57 sampling points are sequentially set on the upper and lower straight sides of Figure 24 . The distribution of the lateral resonance distances of each sampling point is statistically analyzed to generate Figure 20 . The lateral resonance distances of each sampling point are distributed in the range of 2014.6 um to 133632 um, and the median value reaches 26175.4 um. Comparing

[0122] it can be seen that even if the lower truncated side is horizontal and the lower half of the entire resonator is symmetric about the short axis, it does not result in a reduction or concentration of the lateral resonance distance. This also corroborates the effectiveness of the technical solution provided in this application. Figure 25 shown. Figure 25It is a schematic diagram of another effective region shape constructed by using the above method. Among them, the length a of the major semi-axis of the composite ellipse is 76.1um, the length b1 of the minor semi-axis of the upper semi-ellipse is 56.4um, the length b2 of the minor semi-axis of the lower semi-ellipse is 43.4um, the upper intercept d1 is 42.3um, the lower intercept d2 is 34.7um, the upper inclination angle α1 is 15 degrees, and the lower inclination angle α2 is 10 degrees. The upper inclination angle and the lower inclination angle are set to have the same sign and the same value. In this way, the positions of the two straight edges projected on each other will be somewhat misaligned compared with the previous embodiment. In this way, a more flexible and variable resonator shape can be obtained, which is more convenient for the layout design, especially for the connection based on the straight edges between different piezoelectric devices.

[0123] In a sampling manner similar to the above embodiment, on Figure 25 the upper and lower straight edges of, 66 sampling points are sequentially set, and the distribution of the lateral resonance distances of each sampling point is statistically analyzed to generate Figure 26 . The lateral resonance distances of each sampling point are distributed in the range of 1203.5um to 211700.6um, and the median value reaches 28638.05um. It can be seen that although there is a slight misalignment between the two straight edges, it does not cause a reduction or concentration of the lateral resonance distances. This also corroborates the effectiveness of the technical solution provided by this application.

[0124] In some embodiments, Figure 15 when the upper intercept in is equal to the length of the first minor axis and α1 = 0, the length of the upper intercept edge (the first truncated edge) is 0, and the upper intercept edge does not exist; or, when the lower intercept is equal to the length of the second minor axis and α2 = 0, the length of the lower intercept edge (the second truncated edge) is 0, and the lower intercept edge does not exist. In these two cases, only one truncated edge is included in the truncated composite ellipse.

[0125] In some preferred embodiments, in order to avoid the concentration of the distribution of the lateral resonance distances caused by the symmetric characteristics, it can be set that when there is only one truncated edge as described above, the inclination angle of this truncated edge is not 0 degrees, that is, it is not parallel to the major axis.

[0126] Taking the previous case where only the upper intercept edge is included as an example, its corresponding shape is as Figure 27 shown. Among them, the upper inclination angle is 10 degrees, and there is only the upper intercept edge and no lower intercept edge.

[0127] In each of the above embodiments, the shape of the effective region includes elliptical arcs. However, in currently commonly used EDA software, elliptical arc curves are difficult to implement, the design difficulty is high, and it is not conducive to accurately calculating the area of the effective region, which is likely to lead to design deviations.

[0128] Based on this, in some other embodiments of the present application, a concept of polyline approximation for the elliptical arcs in the above-mentioned effective region is also provided. The elliptical arcs are replaced by their inscribed polylines, so as to convert the shape of the effective region (compound ellipse, truncated compound ellipse) in the above-mentioned embodiments into a polygon with a similar contour to solve the above problems.

[0129] In some specific implementation manners, the following algorithm can be used to implement the polyline approximation of the elliptical arcs.

[0130] 1) Taking the midpoint of the major axis as the origin, the line where the major axis is located as the x-axis, and the line where the minor axis is located as the y-axis, a coordinate system is constructed;

[0131] 2) Starting from the positive x-axis direction, inner contact points are taken from the edge of the ellipse corresponding to the effective region with a step angle δ, and β = nδ is used as the sampling angle, where n = 1, 2, …, 360 / δ;

[0132] 3) When n ≤ 180 / δ, the inner contact points are located in the upper half (the first elliptical region) of the effective region. The point with coordinates (acosβ, b1sinβ) is selected as the nth inner contact point. If there is an upper truncated edge and the inner contact point and the origin are on both sides of the upper truncated edge (the inner contact point is on the upper side of the line where the upper truncated edge is located), then this point is discarded;

[0133] When n > 180 / δ, the inner contact points are located in the lower half (the second elliptical region) of the effective region. The point with coordinates (acosβ, b2sinβ) is selected as the nth inner contact point. If there is a lower truncated edge and the inner contact point and the origin are on both sides of the lower truncated edge (the inner contact point is on the lower side of the line where the lower truncated edge is located), then this point is discarded;

[0134] 4) The endpoints of each truncated edge in the effective region are sequentially connected to the retained inner contact points to obtain the final polygon.

[0135] Figure 28 is based on the above algorithm for Figure 16 the polyline approximation of the elliptical arcs in the truncated compound ellipse in. In this embodiment, the step angle δ is set to 18 degrees, and 20 inner contact points are selected on the entire compound ellipse circumference. After finally discarding 4 inner contact points above the upper truncated line and 4 inner contact points below the lower truncated line, together with the endpoints of the upper truncated edge and the endpoints of the lower truncated edge, a 16-sided polygon is formed, and the overall still retains the contour of the original compound ellipse. Just because of this, the region above the major axis is still called the first elliptical region, and the region below the major axis is still called the second elliptical region.

[0136] In a sampling manner similar to the above-mentioned embodiment, 59 sampling points are sequentially set on the Figure 28 upper and lower straight edges of, and the distribution of the transverse resonance distances of each sampling point is statistically analyzed to generateFigure 29 。The transverse resonance distances at each sampling point are distributed in the range of 682.9 um to 244857.4 um, and the median value reaches 21528.3 um. Compared with Figure 25 , there is no particularly significant change in the overall numerical values and distributions before and after the linearization.

[0137] However, a concentrated distribution occurs in local areas, such as Figure 28 the two regions of 8, 9, 10 and 50, 51, 52 in . This is because in this embodiment, in order to simplify the calculation, a relatively large step angle is selected, the line segment length of the inscribed broken line is relatively long, and the difference from the original elliptical arc is large. By reducing the step angle and increasing the number of sampling points of the inscribed points, the polygon after linearization can be made closer to the shape before linearization, and the numerical values and distribution of the transverse resonance distances will also be closer, so as to avoid the above problems introduced by the relatively long straight sides of the inscribed broken line.

[0138] In the actual application scenario, the length of each line segment of the inscribed broken line generated after the above linearization can be 1 um to 50 um. The smaller the length, the closer the inscribed broken line is to the original elliptical arc; the larger the length, the stronger the sense of edges and corners of the inscribed broken line.

[0139] In some other embodiments, by adjusting the length of the line segments of the inscribed broken line, the shape of the generated effective region can be further adjusted to meet other design requirements.

[0140] Furthermore, according to the requirements of the area of the actual effective region, the designed composite ellipse can be enlarged or reduced proportionally and finely adjusted to meet the requirements of the preset area.

[0141] This application also provides an electrode of a piezoelectric device. The electrode is used as the first electrode and / or the second electrode of the piezoelectric device described in the above embodiments to form the effective region.

[0142] In some embodiments, this electrode can be used as the upper electrode of the piezoelectric device, and the shape of this electrode is the shape of the effective region.

[0143] Figure 30 is a schematic structural diagram of a piezoelectric filter including the piezoelectric device provided by this application. Four series resonators S1 to S4 are connected in series between the first port and the second port. The connection points of adjacent series resonators and the second port are respectively connected to one end of parallel resonators P1 to P4. The other ends of parallel resonators P1 and P2 are grounded via inductor L1, and the other ends of parallel resonators P3 and P4 are grounded via inductor L2. A mass load is provided on the parallel resonators to make the anti-resonance frequency of the parallel resonators basically equivalent to the resonance frequency of the series resonators, forming the basic frequency response curve of the filter.

[0144] Figure 31 It is a schematic structural diagram of an electronic device including the piezoelectric device provided in the application. The electronic device is disclosed as a multi-mode and multi-band communication device module in this embodiment. 100 is an antenna port, responsible for wireless transmission and reception with the outside world. 110 is a switching device on the receiving and transmitting channel of frequency band A, 113 is a switching device on the receiving channel of frequency band B, 116 is a switching device on the transmitting channel of frequency band B, and one ends of 110, 113, and 116 are commonly connected to 100. The other end of 110 is connected to the receiving filter 120 of channel A and the transmitting filter 122 of channel A. 120 and 122 together form a duplexer of channel A, and both are packaged on the same carrier board. The other end of 120 is connected to the receiving amplifier 130 of channel A, and the other end of 130 is connected to the receiving port 160 of channel A. The other end of 122 is connected to the transmitting amplifier 132 of channel A, and the other end of 132 is connected to the transmitting port 162 of channel A. 160 and 162 are connected to the corresponding ports of the transceiver of the communication device through leads. The other end of 113 is connected to the receiving filter 124 of channel B, the other end of 124 is connected to the receiving amplifier 134 of channel B, and the other end of 134 is connected to the receiving port 164 of channel B. The other end of 116 is connected to the transmitting filter 126 of channel B, the other end of 126 is connected to the transmitting amplifier 136 of channel B, and the other end of 136 is connected to the transmitting port 166 of channel B. 164 and 166 are connected to the corresponding ports of the transceiver of the communication device through leads. Each filter included in the communication module contains at least one piezoelectric device provided in this application. The module realizes functions such as signal transmission, gating, filtering, and amplification between the transceiver and the antenna in frequency bands A and B. Frequency band A is the standard FDD communication frequency band specified by the 3GPP communication protocol, such as N1, N2, N3, N5, N7, N8, etc. Frequency band B is the standard TDD communication frequency band specified by the mobile communication protocol, such as N40, N41, N77, N78, N79, etc., or it can also be the Wi-Fi communication frequency band specified by the WLAN protocol, such as Wi-Fi-2.4G, Wi-Fi-5G, Wi-Fi-6G, etc.

Claims

1. A piezoelectric device, characterized in that, Comprising: A first electrode, a piezoelectric layer, a second electrode, an acoustic mirror, and a substrate stacked in sequence; The overlapping regions of the first electrode, the piezoelectric layer, the second electrode, and the acoustic mirror in the stacking direction form the effective region of the piezoelectric device; The effective region includes a first elliptical region and a second elliptical region; The first elliptical region includes a major axis side and a first elliptical arc corresponding to the major axis side and a first minor axis; the second elliptical region includes the major axis side and a second elliptical arc corresponding to the major axis side and a second minor axis; the first elliptical arc and the second elliptical arc are respectively connected at two end points of the major axis side; Wherein, the first elliptical region and the second elliptical region are adjacent to each other in the same plane with the major axis side as the boundary; the first minor axis and the second minor axis are not of equal length.

2. The piezoelectric device according to claim 1, wherein The first elliptical arc is a semi-elliptical arc corresponding to the major axis side and the first minor axis; The second elliptical arc is a semi-elliptical arc corresponding to the major axis side and the second minor axis.

3. The piezoelectric device according to claim 2, characterized in that, Further comprising: An input end and an output end; The input end is connected to the first electrode, and the output end is connected to the second electrode; The input end and the output end are respectively arranged at two end points of the major axis side.

4. The piezoelectric device according to claim 1, wherein The first elliptical region further includes a first truncated edge, and the first truncated edge is connected to the first elliptical arc; the first truncated edge is not parallel to the major axis side; the second elliptical arc is a semi-elliptical arc corresponding to the major axis side and the second minor axis; Or, The second elliptical region further includes a second truncated edge, and the second truncated edge is connected to the second elliptical arc; the second truncated edge is not parallel to the major axis side; the first elliptical arc is a semi-elliptical arc corresponding to the major axis side and the first minor axis.

5. The piezoelectric device according to claim 1, characterized in that, The first elliptical region further includes a first truncated edge, and the first truncated edge is connected to the first elliptical arc; The second elliptical region further includes a second truncated edge, and the second truncated edge is connected to the second elliptical arc; Wherein, the first truncated edge and the second truncated edge are not parallel.

6. A piezoelectric device, characterized in that, Replace the first elliptical arc in the piezoelectric device according to any one of claims 1-5 with the inscribed broken line of the first elliptical arc; replace the second elliptical arc with the inscribed broken line of the second elliptical arc.

7. An electrode of a piezoelectric device, characterized in that, The electrode is used as the first electrode and / or the second electrode of the piezoelectric device according to any one of claims 1-6 to form the effective region.

8. A design method of a piezoelectric device, characterized in that, The piezoelectric device includes a first electrode, a piezoelectric layer, a second electrode, an acoustic mirror, and a substrate that are stacked in sequence; the overlapping regions of the first electrode, the piezoelectric layer, the second electrode, and the acoustic mirror in the stacking direction form the effective region of the piezoelectric device; the effective region includes a first elliptical region and a second elliptical region; the first elliptical region includes a major axis side and an inscribed broken line of a first elliptical arc corresponding to the major axis side and a first minor axis; the second elliptical region includes the major axis side and an inscribed broken line of a second elliptical arc corresponding to the major axis side and a second minor axis; the inscribed broken line of the first elliptical arc and the inscribed broken line of the second elliptical arc are respectively connected at two end points of the major axis side; wherein, the first elliptical region and the second elliptical region are adjacent to each other in the same plane with the major axis side as the boundary; the first minor axis and the second minor axis are not of equal length; the method includes: Determine the first ellipse and the second ellipse; Determine the first elliptical arc from the first ellipse; Determine the second elliptical arc from the second ellipse; Select a corresponding number of points from the first ellipse and the second ellipse at a set step angle; Select the points located on the first elliptical arc and the second elliptical arc from the selected corresponding number of points as the in-contact points; Connect the in-contact points, the end points of the first elliptical arc, and the end points of the second elliptical arc in sequence to form the inscribed broken line of the first elliptical arc and the inscribed broken line of the second elliptical arc, so as to form the effective region.

9. A piezoelectric filter, characterized in that, Include: The piezoelectric device according to any one of claims 1-6.

10. An electronic device, characterized in that, Include: The piezoelectric filter according to claim 9.

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