A bulk acoustic wave resonator and electrode design method thereof

Abstract

The present application provides a bulk acoustic wave resonator and an electrode design method thereof, which relates to the field of resonator technology. The bulk acoustic wave resonator includes a substrate and a bottom electrode, a piezoelectric layer and a top electrode stacked on the substrate in sequence. The bottom electrode and / or the top electrode has an orthographic projection located on the substrate. The contour of the orthographic projection is formed by connecting multiple curve segments end to end in sequence. The multiple curve segments are all intercepted from line segments near the non-end points of multiple Bezier curves, and the order of the Bezier curve is equal to or greater than 2. The use of this electrode contour can have a high degree of irregularity, especially the electrode contour obtained by further optimizing the Bezier curve can further suppress pseudo-modes, so that the bulk acoustic wave resonator has better performance.

Description

Technical Field

[0001] The present application relates to the technical field of resonators, and in particular to a bulk acoustic wave resonator and an electrode design method thereof. Background Art

[0002] RF filters are widely used in military and civilian fields such as radar communications and RF front-ends. Film bulk acoustic resonator (FBAR) has become one of the key components for building RF bandpass filters due to its high quality factor, low loss, high reliability, and miniaturization.

[0003] The working principle of FBAR is to apply radio frequency electrical signals through the upper and lower electrodes, and use the inverse piezoelectric effect of the piezoelectric layer material to convert the electrical signals into high-frequency vibrations of the film to generate acoustic wave signals. FBAR mainly produces longitudinal waves that propagate along the thickness direction, and inevitably there will be transverse acoustic waves. Transverse acoustic waves tend to be continuously reflected at the boundary to form standing waves, thereby forming ripples in the impedance curve of the resonator, that is, generating pseudo-modes, thereby reducing the performance of the resonator. Therefore, it is necessary to reasonably design the electrode shape of the resonator to alleviate the pseudo-modes caused by transverse acoustic waves.

[0004] In the prior art, irregular pentagons are usually used as the mainstream electrode shape, which uses non-parallel boundaries to increase the reflection distance of transverse sound waves, thereby alleviating the pseudo-mode caused by transverse sound waves. However, with the continuous development of radio frequency technology, the existing resonator using irregular pentagons as electrode shapes can no longer meet the needs. Summary of the invention

[0005] The purpose of the present application is to provide a bulk acoustic wave resonator and an electrode design method thereof to address the deficiencies in the above-mentioned prior art.

[0006] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] According to one aspect of an embodiment of the present application, a bulk acoustic wave resonator is provided, comprising a substrate and a bottom electrode, a piezoelectric layer and a top electrode stacked in sequence on the substrate, wherein the bottom electrode and / or the top electrode has an orthographic projection located on the substrate, and an outline of the orthographic projection is formed by connecting a plurality of curve segments in sequence end to end, wherein the plurality of curve segments are all intercepted from line segments near non-end points of a plurality of Bezier curves, and the order of the Bezier curves is equal to or greater than 2.

[0008] Optionally, each Bezier curve includes a starting control point, at least one intermediate control point and an ending control point, the starting control point, the intermediate control point and the ending control point of each Bezier curve are part or all of the vertices of a preset polygon, and the starting control points of multiple Bezier curves are selected sequentially from all the vertices of the preset polygon.

[0009] Optionally, the preset polygon has no parallel sides.

[0010] Optionally, the curvature radii of the curvature circles of two adjacent curved line segments at the same connection point are equal.

[0011] Optionally, when the order of the Bezier curve is greater than 2, the number of the plurality of curve segments is equal to or greater than the number of the plurality of Bezier curves.

[0012] Optionally, when the degree of the Bezier curve is equal to 2, the number of the plurality of curve segments is equal to the number of the plurality of Bezier curves.

[0013] Another aspect of the present application provides a method for designing an electrode of a bulk acoustic wave resonator, the method comprising:

[0014] Obtain multiple intersecting Bezier curves and intersection points among the multiple Bezier curves, wherein the intersection points do not include the endpoints of the Bezier curves, and the order of the Bezier curves is equal to or greater than 2;

[0015] Determine the line segments near the non-end points of the Bezier curve according to the intersection points;

[0016] Some or all of the non-endpoint vicinity line segments connected end to end at the intersection are selected from the non-endpoint vicinity line segments of the multiple Bezier curves as multiple curve segments, so that the multiple curve segments are connected end to end in sequence to form an electrode contour.

[0017] Optionally, obtaining a plurality of mutually intersecting Bezier curves and intersection points among the plurality of Bezier curves includes:

[0018] Get the preset polygon and the vertices of the preset polygon;

[0019] Selecting part or all of the vertices of the preset polygon as the starting control point, at least one intermediate control point and the ending control point of each Bezier curve, and the starting control points of the multiple Bezier curves are sequentially selected from all the vertices of the preset polygon;

[0020] A plurality of mutually intersecting Bezier curves are constructed according to a starting control point, at least one intermediate control point and a terminal control point of each Bezier curve, and intersection points among the plurality of Bezier curves are determined.

[0021] Optionally, the preset polygon has no parallel sides.

[0022] Optionally, the curvature radii of the curvature circles of two adjacent curved line segments at the same connection point are equal.

[0023] The beneficial effects of this application include:

[0024] The present application provides a bulk acoustic wave resonator and an electrode design method thereof, wherein the bulk acoustic wave resonator comprises a substrate and a bottom electrode, a piezoelectric layer and a top electrode sequentially stacked on the substrate, wherein the bottom electrode and / or the top electrode has an orthographic projection located on the substrate, and the contour of the orthographic projection is formed by connecting a plurality of curve segments end to end in sequence, wherein the plurality of curve segments are all intercepted from line segments near non-end points of a plurality of Bezier curves, and the order of the Bezier curves is equal to or greater than 2. The use of such an electrode contour can have a high degree of irregularity, and in particular, the electrode contour finally obtained by further optimizing the Bezier curve can further suppress pseudo-modes, so that the bulk acoustic wave resonator has better performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 One of the schematic diagrams of an electrode design process provided in an embodiment of the present application;

[0027] Figure 2 One of the structural schematic diagrams of an electrode profile provided in an embodiment of the present application;

[0028] Figure 3 A second schematic diagram of an electrode design process provided in an embodiment of the present application;

[0029] Figure 4 A second schematic diagram of the structure of an electrode profile provided in an embodiment of the present application;

[0030] Figure 5 A third schematic diagram of an electrode design process provided in an embodiment of the present application;

[0031] Figure 6 A third structural schematic diagram of an electrode profile provided in an embodiment of the present application;

[0032] Figure 7 A fourth structural schematic diagram of an electrode profile provided in an embodiment of the present application;

[0033] Figure 8 The BAW resonator with pentagonal electrode profile is different from the BAW resonator with pentagonal electrode profile adopted in the present application. Figure 6 Schematic diagram of the electrode profiles and respective impedance curves of the BAW resonators.

[0034] Icons: 110-preset polygon; 10-electrode outline; 11-first middle line segment; 12-second middle line segment; 13-third middle line segment; 14-fourth middle line segment; 15-fifth middle line segment; 16-sixth middle line segment; 17-seventh middle line segment; 18-eighth middle line segment; 19-ninth middle line segment; 20-tenth middle line segment; 21-eleventh middle line segment; 22-twelfth middle line segment; 23-thirteenth middle line segment; 24-fourteenth middle line segment; 25-fifteenth middle line segment; 26-sixteenth middle line segment; 27-seventeenth middle line segment; 28-eighteenth middle line segment; 29-nineteenth middle line segment; 30-twentieth middle line segment; 31-twenty-first middle line segment. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. It should be noted that, in the absence of conflict, the various features in the embodiments of the present application can be combined with each other, and the combined embodiments are still within the scope of protection of the present application.

[0037] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0038] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0039] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] The present application provides a bulk acoustic wave resonator, the electrode shape used in the bulk acoustic wave resonator can further alleviate the pseudo mode caused by the transverse acoustic wave, thereby effectively improving the performance of the bulk acoustic wave resonator, so that the filter constructed by the bulk acoustic wave resonator can meet higher radio frequency requirements.

[0042] In order to optimize the pseudo-mode caused by the transverse acoustic wave, it is necessary to design the electrode shape in the BAW resonator. The following provides an electrode design method for a BAW resonator, which includes:

[0043] S1: obtaining a plurality of mutually intersecting Bezier curves and intersection points among the plurality of Bezier curves, wherein the intersection points do not include endpoints of the Bezier curves, and the order of the Bezier curves is equal to or greater than 2.

[0044] In the process of designing the electrode shape, the Bezier curve can be introduced. Thus, on the one hand, the irregularity can be improved, and on the other hand, the Bezier curve is relatively smooth and has no sharp corners. The Bezier curve can be controlled by multiple points. When the points P0, P1, ..., Pn are given, the general parameter formula of the Bezier curve is:

[0045]

[0046]

[0047] Wherein, t∈[0,1], point Pi is the control point of the Bezier curve, the Bezier polygon is connected by the control points of the Bezier curve with a line, starting from P0 and ending at Pn. Controlling the positions of given points P0, P1, ..., Pn can reasonably design the shape of the Bezier curve and the shape of the Bezier polygon.

[0048] n is the control number of the Bezier curve order. When n is 1, the control points are P0 and P1 (P0 is the starting control point and P1 is the ending control point), and the Bezier curve order is 1, that is, it is a line segment.

[0049] When n is 2, the control points are P0, P1, and P2 (P0 is the starting control point and P2 is the ending control point), the order of the Bezier curve is 2, and the general parameter formula of the Bezier curve is:

[0050] B(t)=(1-t) 2 P0+2t(1-t) 2 P1+t 2 P2

[0051] Where t∈[0,1].

[0052] When n is greater than or equal to 3, the control points are P0, P1, P2, and P3 (P0 is the starting control point and P3 is the ending control point), the order of the Bezier curve is 3, and the general parameter formula of the Bezier curve is:

[0053] B(t)=(1-t) 3 P0+3t(1-t) 2 P1+3t 2 (1-t)P2+t 3 P3

[0054] Where t∈[0,1].

[0055] Please refer to (3) in 1. Figure 3 (4) or Figure 5 In (5), first, a plurality of Bezier curves are obtained, and the order of all Bezier curves is greater than or equal to 2, so the number of control points of each Bezier curve is equal to or greater than 3. The plurality of Bezier curves intersect each other, so that an intersection is formed at each intersection position, and each Bezier curve has at least two intersections. Of course, the intersection does not include the two end points of the Bezier curve.

[0056] Specific, for example Figure 1 (3) in FIG. 1 shows three second-order Bezier curves, and the control points of the three Bezier curves are ABC (point A is the starting control point, point B is the middle control point, and point C is the ending control point), BCA (point B is the starting control point, point C is the middle control point, and point A is the ending control point), and CAB (point C is the starting control point, point A is the middle control point, and point B is the ending control point). Correspondingly, the three Bezier curves intersect with each other to form three intersection points, point a, point b, and point c, and each Bezier curve has two intersection points. Since the three points ABC are sequentially used as the endpoints of the three Bezier curves, the intersection points do not include any point in ABC.

[0057] Or, for example Figure 3 (4) in FIG. 4 shows four second-order Bezier curves, and the control points of the four Bezier curves are ABC (point A is the starting control point, point B is the middle control point, and point C is the ending control point), BCD (point B is the starting control point, point C is the middle control point, and point D is the ending control point), CDA (point C is the starting control point, point D is the middle control point, and point A is the ending control point), and DAB (point D is the starting control point, point A is the middle control point, and point B is the ending control point). Correspondingly, the four Bezier curves intersect with each other to form four intersection points a, b, c, and d. Each Bezier curve has two intersection points. Since the four points ABCD are the endpoints of the four Bezier curves in sequence, the intersection points do not include any point in ABCD. For ease of understanding and distinction, all the control points of the Bezier curve will represent the corresponding Bezier curve. For example, when the control point of the second-order Bezier curve is ABC, the Bezier curve ABC is used to refer to the second-order Bezier curve.

[0058] Or, for example Figure 5 (5) in FIG. 5 shows five third-order Bezier curves, and the control points of the five Bezier curves are ABCD (point A is the starting control point, points B and C are the intermediate control points, and point D is the ending control point), BCDE (point B is the starting control point, points C and D are the intermediate control points, and point E is the ending control point), CDEA (point C is the starting control point, points D and E are the intermediate control points, and point A is the ending control point), DEAB (point D is the starting control point, points E and A are the intermediate control points, and point B is the ending control point), and EABC (point E is the starting control point, points A and B are the intermediate control points, and point C is the ending control point). Correspondingly, the five Bezier curves intersect with each other to form multiple intersections, such as at least point a, point b, point c, point d, and point e. Each Bezier curve has at least two intersections. Since the five points ABCDE are sequentially used as the endpoints of the five Bezier curves, the intersection does not include any point in ABCDE.

[0059] S2: Determine the line segments near the non-endpoints of the Bezier curve based on the intersection points.

[0060] According to the intersection points obtained above, and each Bezier curve has at least two intersection points, at least one non-endpoint near line segment can be intercepted from the Bezier curve using two adjacent intersection points. In other words, each non-endpoint near line segment belongs to a segment of the Bezier curve it intercepts. Among them, the non-endpoint near line segment refers to the line segment that does not include the two endpoints of the Bezier curve, so it can also be called the middle line segment.

[0061] Specific, for example Figure 1(3) in the figure, using the intersection point a to point b, we can intercept or determine a middle line segment from the Bezier curve ABC, which can be used Figure 2 Similarly, using the intersection point b to point c, a middle line segment can be intercepted or determined from the Bezier curve BCA, which can be expressed as Figure 2 The second middle line segment 12 in the middle line segment is used to represent the middle line segment. By using the intersection point c to point a, a middle line segment can be intercepted or determined from the Bezier curve CAB, which can be used Figure 2 The third middle line segment 13 in FIG. 1 is used to represent the middle line segment.

[0062] Or, for example Figure 3 (4) in the figure, using the intersection point a to point b, we can intercept or determine a middle line segment from the Bezier curve ABC, which can be used Figure 4 Similarly, using the intersection point b to point c, a middle line segment can be intercepted or determined from the Bezier curve BCD, which can be used Figure 4 The fifth middle line segment 15 in the figure is used to represent the middle line segment. By using the intersection point c to point d, a middle line segment can be intercepted or determined from the Bezier curve CDA, which can be used Figure 4 The sixth middle line segment 16 in the figure represents the middle line segment. By using the intersection point d to point a, a middle line segment can be intercepted or determined from the Bezier curve DAB, which can be expressed as Figure 4 The seventh middle line segment 17 in FIG. 1 is used to represent the middle line segment.

[0063] Or, for example Figure 5 In (5), the same Bezier curve can have more than two intersection points, for example, Bezier curve ABCD has four intersection points. Therefore, three middle line segments can be intercepted or determined from Bezier curve ABCD using the four intersection points. For Bezier curves BCDE, CDEA, DEAB and EABC, multiple intersection points can be determined according to actual conditions, and then at least one middle line segment can be intercepted or determined from each Bezier curve.

[0064] S3: selecting part or all of the non-endpoint vicinity line segments connected end to end at the intersection from the non-endpoint vicinity line segments of the plurality of Bezier curves as the plurality of curve segments, so that the plurality of curve segments are connected end to end in sequence to form the electrode contour 10 .

[0065] Through all the middle line segments obtained in S2, all or part of the middle line segments can be selected and the selected middle line segments can be used as curve segments. In the selection process, it is necessary to make the selected middle line segments meet the requirement of connecting end to end in sequence at the intersection to form a closed loop. In this way, the selected multiple curve segments can be connected end to end in sequence to form a closed loop, and the figure is used as the electrode contour 10.

[0066] Specifically, for example, Figure 1 In (3), all the middle line segments, namely the first middle line segment 11, the second middle line segment 12 and the third middle line segment 13, are selected as curve segments, so as to obtain Figure 2 The electrode profile 10 is shown.

[0067] Or, for example, from Figure 3 In (4), all the middle line segments, namely the fourth middle line segment 14, the fifth middle line segment 15, the sixth middle line segment 16 and the seventh middle line segment 17 are selected as curve segments, so as to obtain the following: Figure 4 The electrode profile 10 is shown.

[0068] Or, for example, from Figure 5 Select some middle line segments from (5) and combine Figure 6 For example, the eighth middle line segment 18, the ninth middle line segment 19, the tenth middle line segment 20, the eleventh middle line segment 21 and the twelfth middle line segment 22 are selected as curve segments, so as to obtain the following Figure 6 The electrode profile 10 is shown. Of course, it is also possible to combine Figure 7 For example, the thirteenth middle line segment 23, the fourteenth middle line segment 24, the fifteenth middle line segment 25, the sixteenth middle line segment 26, the seventeenth middle line segment 27, the eighteenth middle line segment 28, the nineteenth middle line segment 29, the twentieth middle line segment 30 and the twenty-first middle line segment 31 are selected as curve segments, respectively, so as to obtain the following Figure 7 The electrode profile 10 is shown.

[0069] The electrode profile 10 thus obtained can have a high degree of irregularity, and in particular, the electrode profile 10 finally obtained by further optimizing the Bezier curve can further suppress pseudo-modes, so that the BAW resonator has better performance.

[0070] like Figure 8 As shown, the BAW resonator using the pentagonal electrode profile 10 in the prior art and the BAW resonator using the pentagonal electrode profile 10 in the present application are shown. Figure 6 The impedance curves of the BAW resonators of the electrode profiles 10 are shown. Figure 8 It can be seen from the two elliptical circles in that the impedance curve of the BAW resonator of the present application has fewer ripples and can effectively suppress pseudo-modes.

[0071] Optionally, when obtaining multiple intersecting Bezier curves and intersection points of multiple Bezier curves through S1, a preset polygon 110 may be introduced, and the vertices of the preset polygon 110 may be used sequentially as control points of the Bezier curves, thereby obtaining multiple intersecting Bezier curves. Specifically, it includes:

[0072] S1.1: Obtain a preset polygon 110 and vertices of the preset polygon 110.

[0073] The preset polygon 110 is first obtained, and thus, a plurality of vertices of the preset polygon 110 can be obtained.

[0074] For example Figure 1 The preset polygon 110 shown in (1) is a triangle, and the triangle has three vertices A, B and C.

[0075] Or, for example Figure 3 The preset polygon 110 shown in (1) is a quadrilateral, and correspondingly, the quadrilateral has four vertices A, B, C and D.

[0076] Or, for example Figure 5 The preset polygon 110 shown in (1) is a pentagon, and correspondingly, the pentagon has five vertices A, B, C, D and E.

[0077] S1.2: Select some or all vertices of the preset polygon 110 as the starting control point, at least one intermediate control point and the ending control point of each Bezier curve, and the starting control points of multiple Bezier curves are selected sequentially from all vertices of the preset polygon 110.

[0078] After the specific shape of the preset polygon 110 is determined by S1.1, some or all of the vertices in the preset polygon 110 can be selected, and the selected vertices are used as the starting control point, at least one intermediate control point and the ending control point of each Bezier curve. In order to construct different Bezier curves and the multiple Bezier curves finally constructed can form the aforementioned middle line segment (which can be used to form the electrode contour 10) by crossing each other, the next Bezier curve can be displaced by one vertex in the clockwise or counterclockwise direction when selecting points. That is, the starting control points of multiple Bezier curves are selected sequentially from all the vertices of the preset polygon 110.

[0079] Specific, for example Figure 1As shown in (1), the preset polygon 110 is a triangle. Since the order of the Bezier curve needs to be equal to or greater than 2, a 2nd-order Bezier curve (three control points) is selected. Therefore, all vertices of the triangle are selected when constructing the Bezier curve. When selecting the starting control point of the first Bezier curve, point A is selected. Correspondingly, point B is selected as the middle control point and point C is selected as the ending control point in sequence. Then refer to Figure 1 In (2), when selecting the starting control point of the second Bezier curve, select point B in the clockwise direction. Correspondingly, select point C as the middle control point and point A as the ending control point. Finally, refer to Figure 1 In (3), when selecting the starting control point of the third Bezier curve, point C is selected in the clockwise direction. Correspondingly, point A is selected as the middle control point and point B is selected as the ending control point.

[0080] Or, for example Figure 3 As shown in (1) in FIG. 1 , the preset polygon 110 is a quadrilateral, and a second-order Bezier curve is selected. Therefore, three of the four vertices of the quadrilateral can be selected as control points of the same Bezier curve (of course, in other embodiments, a third-order Bezier curve can also be selected. Correspondingly, all vertices of the quadrilateral need to be selected when constructing the Bezier curve). First, as Figure 3 As shown in (1) in the figure, when selecting the starting control point of the first Bezier curve, point A is selected, and correspondingly, point B is selected as the middle control point and point C is selected as the ending control point in sequence; then refer to Figure 3 In (2), when selecting the starting control point of the second Bezier curve, select point B in the clockwise direction. Correspondingly, select point C as the middle control point and point D as the ending control point. Then refer to Figure 3 In (3), when selecting the starting control point of the third Bezier curve, select point C in the clockwise direction. Correspondingly, select point D as the middle control point and point A as the ending control point. Finally, refer to Figure 3 In (4), when selecting the starting control point of the fourth Bezier curve, point D is selected in the clockwise direction. Correspondingly, point A is selected as the middle control point and point B is selected as the ending control point.

[0081] Or, for example Figure 5 As shown, the preset polygon 110 is a pentagon, and a 3rd order Bezier curve is selected. Therefore, four of the five vertices of the pentagon can be selected as control points of the same Bezier curve (of course, in other implementations, a 2nd order or 4th order Bezier curve can also be selected. Correspondingly, three vertices or all vertices of the pentagon need to be selected when constructing the Bezier curve). Figure 5As shown in (1) in the figure, when selecting the starting control point of the first Bezier curve, point A is selected. Correspondingly, points B and C are selected in sequence as the intermediate control points, and point D is selected as the ending control point. Then refer to Figure 5 In (2), when selecting the starting control point of the second Bezier curve, select point B in the clockwise direction. Correspondingly, select points C and D as the intermediate control points in sequence, and point E as the ending control point. Then refer to Figure 5 In (3), when selecting the starting control point of the third Bezier curve, select point C in the clockwise direction. Correspondingly, select points D and E as the intermediate control points in sequence, and point A as the ending control point. Then refer to Figure 5 In (4), when selecting the starting control point of the fourth Bezier curve, select point D in the clockwise direction. Correspondingly, select points E and A as the intermediate control points in sequence, and point B as the ending control point. Finally, refer to Figure 5 In (5), when selecting the starting control point of the fifth Bezier curve, point E is selected in the clockwise direction. Correspondingly, points A and B are selected in sequence as the intermediate control points, and point C is selected as the ending control point.

[0082] S1.3: Construct multiple mutually intersecting Bezier curves according to the starting control point, at least one intermediate control point and the ending control point of each Bezier curve, and determine the intersection points among the multiple Bezier curves.

[0083] According to each control point of each Bezier curve determined above, multiple intersecting Bezier curves can be constructed, and each intersection point can be determined according to the intersecting situation.

[0084] Specifically, for example, combining Figure 1 As shown in (1) to (3) in , Bezier curve ABC, Bezier curve BCA and Bezier curve CAB can be obtained in sequence. Figure 1 (3) and Figure 2 According to Bezier curve ABC, Bezier curve BCA and Bezier curve CAB, the intersection points a, b and c are obtained.

[0085] Or, for example Figure 3 As shown in (1) to (4) in , Bezier curve ABC, Bezier curve BCD, Bezier curve CDA and Bezier curve DAB can be obtained in sequence. Figure 3 (4) and Figure 4 According to Bezier curve ABC, Bezier curve BCD, Bezier curve CDA and Bezier curve DAB, the intersection points a, b, c and d are obtained.

[0086] Or, for example Figure 5As shown in (1) to (5) in , Bezier curve ABCD, Bezier curve BCDE, Bezier curve CDEA, Bezier curve DEAB and Bezier curve EABC can be obtained in sequence. Figure 6 , select some intersection points a, b, c, d, e according to Bezier curve ABCD, Bezier curve BCDE, Bezier curve CDEA, Bezier curve DEAB and Bezier curve EABC. Or, Figure 7 , select some intersection points a, b, c, d, e, h, i, g, k according to Bezier curve ABCD, Bezier curve BCDE, Bezier curve CDEA, Bezier curve DEAB and Bezier curve EABC.

[0087] Optionally, the preset polygon 110 does not have parallel sides, for example Figure 1 , Figure 3 or Figure 5 As shown, no two sides of the triangle, quadrilateral or pentagon are parallel, which can help to increase the irregularity of the final electrode profile 10 .

[0088] Optionally, the curvature radii of the curvature circles of two adjacent curved segments at the same connection point are equal. This can avoid the occurrence of sharp corners at the intersection of the two curved segments (i.e., the connection point of the two curved segments), which helps to improve the performance of the resonator and facilitates processing. Figure 2 In the figure, the first middle line segment 11 and the second middle line segment 12 are tangent at the intersection point b, so that the curvature radii of the curvature circles of the first middle line segment 11 and the second middle line segment 12 at point b are equal. Similarly, the two curve segments at points c and a also satisfy the tangent property. Figure 4 , Figure 6 and Figure 7 The same is true for all shown.

[0089] Optionally, the electrode profile 10 has no inner concave edge, so as to improve the electromechanical coupling coefficient of the resonator.

[0090] In one aspect of an embodiment of the present application, a bulk acoustic wave resonator is provided. The electrode of the bulk acoustic wave resonator can be obtained according to the above method.

[0091] In one aspect of an embodiment of the present application, a bulk acoustic wave resonator is provided, comprising a substrate and a bottom electrode, a piezoelectric layer, and a top electrode sequentially stacked on the substrate. When designing the electrode profile 10, the electrode profile 10 of the bottom electrode can be designed, the electrode profile 10 of the top electrode can be designed, or the electrode profiles 10 of the bottom electrode and the top electrode can be designed simultaneously.

[0092] The electrode to be designed has an orthographic projection on the substrate along the thickness direction of the substrate, and the contour of the orthographic projection is the contour of the electrode. The contour of the orthographic projection is formed by connecting multiple curve segments in sequence, and the multiple curve segments are all intercepted from the middle line segments of multiple Bezier curves, and the order of the Bezier curve is equal to or greater than 2. Based on the relevant description in the aforementioned method, the use of this electrode contour 10 can have a high degree of irregularity, especially the electrode contour 10 obtained by further optimizing the Bezier curve can further suppress pseudo-modes, so that the bulk acoustic wave resonator has better performance.

[0093] Optionally, each Bezier curve includes a starting control point, at least one intermediate control point and an ending control point, the starting control point, the intermediate control point and the ending control point of each Bezier curve are part or all of the vertices of the preset polygon 110, and the starting control points of multiple Bezier curves are selected sequentially from all the vertices of the preset polygon 110.

[0094] Specifically, the preset polygon 110 is first obtained, and thus, a plurality of vertices of the preset polygon 110 can be obtained.

[0095] For example Figure 1 The preset polygon 110 shown in (1) is a triangle, and the triangle has three vertices A, B and C.

[0096] Or, for example Figure 3 The preset polygon 110 shown in (1) is a quadrilateral, and correspondingly, the quadrilateral has four vertices A, B, C and D.

[0097] Or, for example Figure 5 The preset polygon 110 shown in (1) is a pentagon, and correspondingly, the pentagon has five vertices A, B, C, D and E.

[0098] After determining the specific shape of the preset polygon 110, some or all of the vertices in the preset polygon 110 can be selected, and the selected vertices are used as the starting control point, at least one intermediate control point, and the ending control point of each Bezier curve. In order to construct different Bezier curves and the multiple Bezier curves finally constructed can form the aforementioned middle line segment (which can be used to form the electrode contour 10) by crossing each other, the next Bezier curve can be displaced by one vertex in the clockwise or counterclockwise direction when selecting points. That is, the starting control points of multiple Bezier curves are selected sequentially from all the vertices of the preset polygon 110.

[0099] Specific, for example Figure 1As shown in (1), the preset polygon 110 is a triangle. Since the order of the Bezier curve needs to be equal to or greater than 2, a 2nd-order Bezier curve (three control points) is selected. Therefore, all vertices of the triangle are selected when constructing the Bezier curve. When selecting the starting control point of the first Bezier curve, point A is selected. Correspondingly, point B is selected as the middle control point and point C is selected as the ending control point in sequence. Then refer to Figure 1 In (2), when selecting the starting control point of the second Bezier curve, select point B in the clockwise direction. Correspondingly, select point C as the middle control point and point A as the ending control point. Finally, refer to Figure 1 In (3), when selecting the starting control point of the third Bezier curve, point C is selected in the clockwise direction. Correspondingly, point A is selected as the middle control point and point B is selected as the ending control point.

[0100] Or, for example Figure 3 As shown in (1) in FIG. 1 , the preset polygon 110 is a quadrilateral, and a second-order Bezier curve is selected. Therefore, three of the four vertices of the quadrilateral can be selected as control points of the same Bezier curve (of course, in other embodiments, a third-order Bezier curve can also be selected. Correspondingly, all vertices of the quadrilateral need to be selected when constructing the Bezier curve). First, as Figure 3 As shown in (1) in the figure, when selecting the starting control point of the first Bezier curve, point A is selected, and correspondingly, point B is selected as the middle control point and point C is selected as the ending control point in sequence; then refer to Figure 3 In (2), when selecting the starting control point of the second Bezier curve, select point B in the clockwise direction. Correspondingly, select point C as the middle control point and point D as the ending control point. Then refer to Figure 3 In (3), when selecting the starting control point of the third Bezier curve, select point C in the clockwise direction. Correspondingly, select point D as the middle control point and point A as the ending control point. Finally, refer to Figure 3 In (4), when selecting the starting control point of the fourth Bezier curve, point D is selected in the clockwise direction. Correspondingly, point A is selected as the middle control point and point B is selected as the ending control point.

[0101] Or, for example Figure 5 As shown, the preset polygon 110 is a pentagon, and a 3rd order Bezier curve is selected. Therefore, four of the five vertices of the pentagon can be selected as control points of the same Bezier curve (of course, in other implementations, a 2nd order or 4th order Bezier curve can also be selected. Correspondingly, three vertices or all vertices of the pentagon need to be selected when constructing the Bezier curve). Figure 5As shown in (1) in the figure, when selecting the starting control point of the first Bezier curve, point A is selected. Correspondingly, points B and C are selected in sequence as the intermediate control points, and point D is selected as the ending control point. Then refer to Figure 5 In (2), when selecting the starting control point of the second Bezier curve, select point B in the clockwise direction. Correspondingly, select points C and D as the intermediate control points in sequence, and point E as the ending control point. Then refer to Figure 5 In (3), when selecting the starting control point of the third Bezier curve, select point C in the clockwise direction. Correspondingly, select points D and E as the intermediate control points in sequence, and point A as the ending control point. Then refer to Figure 5 In (4), when selecting the starting control point of the fourth Bezier curve, select point D in the clockwise direction. Correspondingly, select points E and A as the intermediate control points in sequence, and point B as the ending control point. Finally, refer to Figure 5 In (5), when selecting the starting control point of the fifth Bezier curve, point E is selected in the clockwise direction. Correspondingly, points A and B are selected in sequence as the intermediate control points, and point C is selected as the ending control point.

[0102] According to each control point of each Bezier curve determined above, multiple intersecting Bezier curves can be constructed, and each intersection point can be determined according to the intersecting situation.

[0103] Specifically, for example, combining Figure 1 As shown in (1) to (3) in , Bezier curve ABC, Bezier curve BCA and Bezier curve CAB can be obtained in sequence. Figure 1 (3) and Figure 2 According to Bezier curve ABC, Bezier curve BCA and Bezier curve CAB, the intersection points a, b and c are obtained.

[0104] Or, for example Figure 3 As shown in (1) to (4) in , Bezier curve ABC, Bezier curve BCD, Bezier curve CDA and Bezier curve DAB can be obtained in sequence. Figure 3 (4) and Figure 4 According to Bezier curve ABC, Bezier curve BCD, Bezier curve CDA and Bezier curve DAB, the intersection points a, b, c and d are obtained.

[0105] Or, for example Figure 5 As shown in (1) to (5) in , Bezier curve ABCD, Bezier curve BCDE, Bezier curve CDEA, Bezier curve DEAB and Bezier curve EABC can be obtained in sequence. Figure 6, select some intersection points a, b, c, d, e according to Bezier curve ABCD, Bezier curve BCDE, Bezier curve CDEA, Bezier curve DEAB and Bezier curve EABC. Or, Figure 7 , select some intersection points a, b, c, d, e, h, i, g, k according to Bezier curve ABCD, Bezier curve BCDE, Bezier curve CDEA, Bezier curve DEAB and Bezier curve EABC.

[0106] Optionally, the preset polygon 110 does not have parallel sides, for example Figure 1 , Figure 3 or Figure 5 As shown, no two sides of the triangle, quadrilateral or pentagon are parallel, which can help to increase the irregularity of the final electrode profile 10 .

[0107] Optionally, the curvature radii of the curvature circles of two adjacent curved segments at the same connection point are equal. This can avoid the occurrence of sharp corners at the intersection of the two curved segments (i.e., the connection point of the two curved segments), which helps to improve the performance of the resonator and facilitates processing. Figure 2 In the figure, the first middle line segment 11 and the second middle line segment 12 are tangent at the intersection point b, so that the curvature radii of the curvature circles of the first middle line segment 11 and the second middle line segment 12 at point b are equal. Similarly, the two curve segments at points c and a also satisfy the tangent property. Figure 4 , Figure 6 and Figure 7 The same is true for all shown.

[0108] Optionally, the electrode profile 10 has no inner concave edge, so as to improve the electromechanical coupling coefficient of the resonator.

[0109] Optionally, when the order of the Bezier curve is greater than 2, the number of the multiple curve segments is equal to or greater than the number of the multiple Bezier curves. When the order of the Bezier curve is high, the number of intersections on the same Bezier curve may be greater than 2, so the number of middle line segments provided by the same Bezier curve may be greater than 1. In the end, 2 or more middle line segments provided by the same Bezier curve may be selected as curve segments. For example Figure 5 and Figure 6 , the Bezier curve ABCD provides an eighth middle line segment 18 and a ninth middle line segment 19 as curve segments.

[0110] Optionally, when the order of the Bezier curve is equal to 2, the number of the plurality of curve segments is equal to the number of the plurality of Bezier curves. In other words, when the order of the Bezier curve is equal to 2, a curve segment can be intercepted from each Bezier curve. Figure 1As shown in , a curve segment is intercepted from each of the three 2nd-order Bezier curves. Figure 2 As shown, a curve segment is intercepted from each of the four 2nd-order Bezier curves.

[0111] Optionally, when determining the preset polygon 110 in the above embodiment, please refer to Figure 1 , Figure 3 or Figure 5 As shown in the figure, with point o as the center point, multiple line segments radiate outward in the direction of the ray, with one end point at point o and the other end point far away from point o. Figure 1 , three line segments radiate outward from point o, forming line segments oA, oB and oC respectively, and then connecting points A, B, and C in sequence in a clockwise or counterclockwise direction to form a triangle, which serves as one of the preset polygons 110. Figure 3 The quadrilateral and Figure 5 The same is true for the pentagon in .

[0112] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A bulk acoustic wave resonator, characterized in that: It includes a substrate and a bottom electrode, a piezoelectric layer and a top electrode stacked in sequence on the substrate, the bottom electrode and / or the top electrode has an orthographic projection located on the substrate, the contour of the orthographic projection is formed by connecting a plurality of curve segments end to end in sequence, the plurality of curve segments are all intercepted from line segments near non-end points of a plurality of Bezier curves, the order of the Bezier curves is equal to or greater than 2, the plurality of Bezier curves intersect with each other to form intersections at the intersection positions, and the plurality of curve segments are selected from the line segments near the non-end points and connected end to end in sequence at the intersections.

2. The bulk acoustic wave resonator according to claim 1, characterized in that Each of the Bezier curves includes a starting control point, at least one intermediate control point and an ending control point. The starting control point, the intermediate control point and the ending control point of each of the Bezier curves are part or all of the vertices of a preset polygon, and the starting control points of the multiple Bezier curves are selected sequentially from all the vertices of the preset polygon.

3. The bulk acoustic wave resonator according to claim 2, characterized in that The preset polygon has no parallel sides.

4. The bulk acoustic wave resonator according to claim 1, characterized in that The curvature radii of the curvature circles of two adjacent curved line segments at the same connection point are equal.

5. The bulk acoustic wave resonator according to any one of claims 1 to 4, characterized in that: When the order of the Bezier curve is greater than 2, the number of the plurality of curve segments is equal to or greater than the number of the plurality of Bezier curves.

6. The bulk acoustic wave resonator according to any one of claims 1 to 4, characterized in that: When the order of the Bezier curve is equal to 2, the number of the plurality of curve segments is equal to the number of the plurality of Bezier curves.

7. A method for designing electrodes of a bulk acoustic wave resonator, characterized in that: The method comprises: Acquire a plurality of mutually intersecting Bezier curves and intersection points among the plurality of the Bezier curves, wherein the intersection points do not include endpoints of the Bezier curves, and the order of the Bezier curves is equal to or greater than 2; Determine a line segment near a non-endpoint of the Bezier curve according to the intersection point; Some or all of the non-endpoint vicinity line segments connected end to end at the intersection are selected from the non-endpoint vicinity line segments of the multiple Bezier curves as multiple curve segments, so that the multiple curve segments are connected end to end in sequence to form an electrode contour.

8. The electrode design method according to claim 7, characterized in that: The step of obtaining a plurality of mutually intersecting Bezier curves and the intersection points of the plurality of Bezier curves comprises: Obtaining a preset polygon and vertices of the preset polygon; Selecting part or all of the vertices of the preset polygon as the starting control point, at least one intermediate control point and the ending control point of each Bezier curve, and the starting control points of the plurality of Bezier curves are sequentially selected from all the vertices of the preset polygon; A plurality of mutually intersecting Bezier curves are constructed according to the starting control point, at least one intermediate control point and the ending control point of each Bezier curve, and intersection points among the plurality of Bezier curves are determined.

9. The electrode design method according to claim 8, characterized in that: The preset polygon has no parallel sides.

10. The electrode design method according to any one of claims 7 to 9, characterized in that: The curvature radii of the curvature circles of two adjacent curved line segments at the same connection point are equal.

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