Elastic wave device, filter, and multiplexer

Abstract

The invention discloses an elastic wave device, a filter and a multiplexer, and belongs to the technical field of elastic waves, the elastic wave device comprises a piezoelectric layer, a quartz substrate and a conductive material film pattern; the conductive material film pattern comprises an interdigital transducer electrode and a reflector electrode; the interdigital transducer electrode comprises M1 transduction electrode fingers, the reflector electrode comprises M2 reflection electrode fingers, the piezoelectric layer is arranged on the quartz substrate along a third direction, the conductive material film pattern is arranged on the piezoelectric layer, and the third direction is the height direction of the elastic wave device; in the first direction, the reflector electrodes are located on the two sides of the interdigital transducer electrode, the piezoelectric layer comprises N1 concave parts, the quartz substrate comprises N1 convex parts, and the first direction is the arrangement direction of the N1 convex parts; and each convex part is matched with two adjacent concave parts, and the condition that N1 / (M1 + M2) is greater than or equal to 1 / 2 is met. According to the invention, while the transverse mode of the elastic wave device is suppressed, forbidden band jitter is reduced, and ohmic loss is reduced.

Description

Technical Field

[0001] The present application relates to the field of elastic wave technology, and in particular to an elastic wave device, a filter and a multiplexer. Background Art

[0002] In the field of existing elastic wave device technology, invention patent application CN118740094A discloses: Figure 1 The schematic diagram of a typical elastic wave device 100 based on a piezoelectric composite substrate is shown. The elastic wave device 100 based on a piezoelectric composite substrate includes a piezoelectric layer 1, a non-piezoelectric substrate 3, and a conductive material film pattern. The piezoelectric layer 1 is located above the non-piezoelectric substrate 3, and the conductive material film pattern is located above the piezoelectric layer 1. The conductive material film pattern includes an interdigital transducer (IDT) electrode 2a, a reflector electrode 2b, a first interdigital transducer bus bar 4a, a second interdigital transducer bus bar, a first reflector bus bar 4b, and a second reflector bus bar. The IDT electrode 2a includes a plurality of transducer electrode fingers, and the plurality of transducer electrodes include a plurality of first electrode fingers and a plurality of second electrode fingers interlaced with each other, and a first interdigital transducer bus bar 4a and a second interdigital transducer bus bar facing each other in the extending direction of the first electrode fingers and the second electrode fingers. The distance between adjacent first electrode fingers (or second electrode fingers) is λ, and the distance λ is also generally referred to as the wavelength of the IDT. A distance AP at which the first electrode finger and the second electrode finger overlap is generally referred to as the aperture of the IDT; the reflector electrode 2b includes a plurality of reflective electrode fingers, the plurality of reflective electrode fingers include a plurality of third electrode fingers and a plurality of fourth electrode fingers interlaced with each other, and a first reflector bus bar 4b and a second reflector bus bar facing each other in the extending direction of the third electrode fingers and the fourth electrode fingers; Figure 2 The admittance / conductance-frequency curve of a typical elastic wave device 100 is shown. From the admittance / conductance-frequency curve, it can be seen that the elastic wave device 100 has a lateral parasitic mode, which is specifically manifested as fluctuations in admittance and conductance between the resonant frequency and the anti-resonant frequency.

[0003] Meanwhile, in the existing elastic wave device technology field, Figure 3 A typical slowness curve of the elastic wave device 100 is shown. From the slowness curve, it can be seen that the slowness curve is convex, and its curvature is greater than 0, and the elastic wave device 100 will generate a transverse mode; Figure 4The cross-sectional view of an elastic wave device 200 is shown. A piezoelectric layer 1 is formed on a quartz substrate 5 and supports the piezoelectric layer 1. A conductive material film pattern is formed on the piezoelectric layer 1. The conductive material film pattern also includes an interdigital transducer electrode, a reflector electrode, a first interdigital transducer bus bar, a second interdigital transducer bus bar, a first reflector bus bar and a second reflector bus bar. Specifically, the direction parallel to the x-axis in the coordinate system is defined as the electrode finger arrangement direction, which is also the elastic wave propagation direction. The direction parallel to the y-axis in the coordinate system is defined as the electrode finger extension direction (not shown in the figure). The direction parallel to the z-axis in the coordinate system is defined as the height direction of the elastic wave device 200. The piezoelectric layer 1 is lithium niobate (LiNbO3), and the Euler angle is (0°, 122°, 0°); the wavelength of the elastic wave is λ; the conductive film material pattern is composed of aluminum electrodes, and the thickness of the aluminum electrodes is h. Al ; The Euler angles of the quartz substrate 5 are (0°, 126°, 0°).

[0004] Figure 5 shows different aluminum electrode thickness h Al The slowness curve of the elastic wave device 200 is shown in FIG. LiNbO3 is 300nm, and the wavelength λ of the elastic wave is 4μm. As the thickness of the aluminum electrode decreases, the curvature of the slowness curve of the elastic wave device 200 gradually decreases from greater than 0 to less than 0. To ensure that the curvature is equal to or less than 0, the thickness of the aluminum electrode h Al Need to meet h Al ≤160nm (4%λ). Therefore, according to the slowness calculation result, it can be known that the thinner the thickness of the conductive material film pattern of the elastic wave device 200 is, the more conducive it is to the lateral mode suppression of the elastic wave device 200; Figure 6 shows different aluminum electrode thickness h Al The admittance-frequency curve of the elastic wave device 200 is shown in FIG. 2 , wherein the thickness of the piezoelectric layer h p is 300nm, and the wavelength λ of the elastic wave is 4μm. It can be seen from the curve that as the thickness of the aluminum electrode is h Al Thinning (i.e. h Al If the reflectivity is reduced, the band gap jitter on the right side of the anti-resonance frequency of the elastic wave device 200 will gradually increase, and the performance will deteriorate. In order to minimize the ohmic loss of the elastic wave device 200 and improve the performance as much as possible, the thickness of the aluminum electrode is preferably h Al It needs to be as big as possible.

[0005] Therefore, when the aluminum electrode thickness h Al Satisfy h AlWhen the thickness is ≤160nm (4%λ), although the transverse mode of the elastic wave device 200 is suppressed, the thinner the thickness of the conductive material film pattern is, the less reflectivity of the device will be, the greater the bandgap jitter will be, and the thinner the electrode will lead to the increase of the ohmic loss of the elastic wave device and the decrease of the quality factor Q value. Therefore, the elastic wave device cannot ensure the suppression of the transverse mode while making the bandgap jitter and ohmic loss as small as possible. A new method is needed to suppress the transverse mode of the elastic wave device while ensuring the bandgap jitter and ohmic loss of the elastic wave device are small. Summary of the invention

[0006] The purpose of this application is to provide an elastic wave device, a filter and a multiplexer to partially or completely solve the problems existing in the above-mentioned prior art. To achieve the above-mentioned purpose, the technical solution adopted by this application is:

[0007] In a first aspect, an elastic wave device includes: a piezoelectric layer, a quartz substrate, and a conductive material film pattern; the conductive material film pattern includes an interdigital transducer electrode and a reflector electrode; the interdigital transducer electrode includes M1 transducer electrode fingers, and the reflector electrode includes M2 reflective electrode fingers;

[0008] Along the third direction, the piezoelectric layer is arranged on the quartz substrate, and the conductive material film pattern is arranged on the piezoelectric layer. The third direction is the height direction of the elastic wave device. Along the first direction, the reflector electrode is located on both sides of the interdigital transducer electrode. The piezoelectric layer includes N1 concave portions, and the quartz substrate includes N1 convex portions. The first direction is the arrangement direction of the N1 convex portions. Each convex portion cooperates with two adjacent concave portions to satisfy: N1 / (M1+M2)≥1 / 2.

[0009] Optionally, along the first direction, the width of the transducing electrode finger and the width of the reflecting electrode finger are equal, both being the electrode width w, and the width of the convex portion is W, satisfying W≥0.6×w.

[0010] Optionally, along the third direction, the piezoelectric layer comprises a first height h p and the second height h t , the height of the convex part is h s , satisfying: h p >h t ,h s ≥0.4×h p .

[0011] Optionally, N1 / (M1+M2)=1, or 1 / 2≤N1 / (M1+M2)<1, or N1 / (M1+M2)>1.

[0012] Optionally, the piezoelectric layer is lithium niobate LiNbO3, and the Euler angle is (0°, 90°-140°, 0°).

[0013] Optionally, the piezoelectric layer is lithium tantalate LiTaO3, and the Euler angle is (0°, 100°-150°, 0°).

[0014] In a second aspect, the present invention provides a filter, comprising: a series arm resonator and a parallel arm resonator; at least one of the series arm resonator and the parallel arm resonator is the elastic wave device described in any one of the first aspects.

[0015] In a third aspect, the present invention provides a multiplexer, comprising: an antenna terminal, the antenna terminal is connected to an antenna; a plurality of filters, the plurality of filters are connected to the antenna terminal; at least one filter is the filter in the second aspect.

[0016] The beneficial effects of the technical solution provided by this application include at least:

[0017] (1) In the present invention, the piezoelectric layer includes N1 concave portions, the quartz substrate includes N1 convex portions, the first direction is the arrangement direction of the N1 convex portions, each convex portion cooperates with two adjacent concave portions, the N1 convex portions, the M1 transducer electrode fingers, and the M2 reflective electrode fingers of the quartz substrate satisfy: N1 / (M1+M2)≥1 / 2, and under the condition of suppressing the transverse mode of the elastic wave device and having the same curvature, the thickness h of the aluminum electrode Al It will be larger, the bandgap jitter of the elastic wave device has been weakened and the ohmic loss has been reduced, achieving the goal of reducing the bandgap jitter and reducing the ohmic loss while suppressing the lateral mode of the elastic wave device.

[0018] (2) In the present application, the piezoelectric layer includes a first height h p and the second height h t , electrode width w, convex width W, convex height h s , satisfying: W ≥ 0.6 × w, h p >h t ,h s ≥0.4×h p , it can control the propagation characteristics of elastic waves, reduce the energy dispersion phenomenon caused by the transverse mode when the elastic wave propagates, make the energy propagate more concentratedly along the predetermined direction, make the longitudinal wave of the elastic wave device dominant, reduce the energy loss and interference caused by the transverse mode, and enable the elastic wave device to work more accurately and stably in practical applications, thereby improving and optimizing the overall performance of the elastic wave device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0020] Figure 1 is a schematic diagram of a typical elastic wave device 100 based on a piezoelectric composite substrate in the prior art;

[0021] Figure 2 is a typical admittance / conductance-frequency graph of an elastic wave device 100 in the prior art;

[0022] Figure 3 is a slowness curve diagram of a typical elastic wave device 100 in the prior art;

[0023] Figure 4 is a cross-sectional view of an elastic wave device 200 in the prior art;

[0024] Figure 5 is the thickness of different aluminum electrodes in the prior art Al A slowness curve diagram of the elastic wave device 200;

[0025] Figure 6 is the thickness of different aluminum electrodes in the prior art Al Admittance-frequency curve of the elastic wave device 200;

[0026] Figure 7 is a cross-sectional view of an elastic wave device 300 according to the present invention;

[0027] Figure 8 is a partially enlarged schematic diagram of the elastic wave device 300 of the present invention;

[0028] Fig. 9 4 is a cross-sectional view of an elastic wave device 400 provided in the present application.

[0029] Fig.10 FIG. 5 is a cross-sectional view of an elastic wave device 500 provided in the present application.

[0030] Fig.11 is the thickness h of the different aluminum electrodes applied in the present invention Al Slowness curve of the elastic wave device.

[0031] Fig.12 is a slowness curve diagram of elastic wave devices with different widths W of the present invention;

[0032] Fig.13 The different heights h of the present invention are s Slowness curve of elastic wave device; DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] Among them, the same parts are represented by the same figure marks. It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings of the present application specification, and the words "bottom surface" and "top surface", "inside" and "outside" refer to the direction towards or away from a specific component, respectively. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application specification, the meaning of "multiple" is two or more.

[0035] In a first aspect, an elastic wave device 300 comprises: a piezoelectric layer 1, a quartz substrate 5 and a conductive material thin film pattern; the conductive material thin film pattern comprises an interdigital transducer electrode and a reflector electrode, and the reflector electrode is located on both sides of the interdigital transducer electrode; the interdigital transducer electrode comprises M1 transducer electrode fingers, and the reflector electrode comprises M2 reflective electrode fingers; along a third direction, the piezoelectric layer 1 is arranged on the quartz substrate 5, and the conductive material thin film pattern is arranged on the piezoelectric layer; along the first direction, the piezoelectric layer 1 comprises N1 recesses, and the quartz substrate 5 comprises N1 protrusions, and the protrusion cooperates with two adjacent recesses to satisfy: N1 / (M1+M2)≥1 / 2.

[0036] In some embodiments, the first direction is the x-axis direction, and the direction parallel to the x-axis is defined as the arrangement direction of the electrode fingers. The x-axis direction is also the elastic wave propagation direction. The first direction is also the arrangement direction of the N1 convex portions. The second direction is the y-axis direction (not shown in the figure, but can be referred to Figure 1 ), the direction parallel to the y-axis is defined as the extension direction of the electrode fingers (not shown in the figure), the third direction is the z-axis direction, and the direction parallel to the z-axis is defined as the height direction of the elastic wave device.

[0037] In some embodiments, the slowness curve is usually expressed as S x and S y The graphs are coordinate axes, representing the components of the slowness vector S in the x-direction and the y-direction respectively. Each point on the curve represents the slowness value of the wave in a certain direction, which can intuitively reflect the anisotropy of the material and the wave propagation characteristics in different directions.

[0038] In some embodiments, Figure 8 As shown, the materials of the interdigital transducer electrode and the reflector electrode are both aluminum. Along the third direction, the height of the transducer electrode finger and the height of the reflector electrode finger are equal, both of which are electrode height h Al Along the first direction, the width of the transducer electrode finger and the width of the reflective electrode finger are equal, both are electrode width w, and the width of the convex portion 66 and the width of the concave portion are equal, both are W.

[0039] In some embodiments, Figure 8 As shown, along the third direction, the piezoelectric layer includes a first height h p and the second height h t , the first height h p Greater than the second height h t The height of the convex part is h s , the first height h p At least it can be understood that: along the third direction, the quartz substrate 5 contacts the bottom of the piezoelectric layer 1 to form a first contact surface, the first contact surface is substantially parallel to the plane (which may be a horizontal plane) formed by the first direction (x-axis direction) and the second direction (y-axis direction), along the third direction, the first contact surface is farthest from the top surface of the piezoelectric layer, and the vertical distance from the first contact surface to the top surface of the piezoelectric layer is the first height h p ; Second height h t At least it can be understood that: along the third direction, the top of the quartz substrate contacts the piezoelectric layer to form a second contact surface, the second contact surface is substantially parallel to the plane (which may be a horizontal plane) formed by the first direction (x-axis direction) and the second direction (y-axis direction), along the third direction, the second contact surface is closest to the top surface of the piezoelectric layer, and the vertical distance from the second contact surface to the top surface of the piezoelectric layer is the second height h t ; The height of the convex part is h s At least it can be understood that: along the third direction, the top surface of the convex portion is substantially parallel to the plane (which may be a horizontal plane) formed by the first direction (x-axis direction) and the second direction (y-axis direction), and the vertical distance from the top surface of the convex portion to the first contact surface is the height of the convex portion, which is h. s .

[0040] In some embodiments, the conductive material film pattern includes an IDT electrode, a reflector electrode, a first IDT bus bar (not shown in the figure, refer to Figure 1 ), the second IDT bus bar (not shown in the figure, can refer to Figure 1 ), the first reflector bus bar (not shown in the figure, can refer to Figure 1 ) and a second reflector bus bar (not shown in the figure, refer to Figure 1), along the first direction, the reflector electrode is located on both sides of the interdigital transducer electrode, the interdigital transducer electrode includes M1 transducer electrode fingers, and the reflector electrode includes M2 reflective electrode fingers, which belong to the common conductive material thin film graphic technology in the existing elastic wave device, and the present invention application will not be repeated here.

[0041] In some embodiments, on the basis of satisfying N1 / (M1+M2)≥1 / 2, the N1 protrusions, M1 transducing electrode fingers, and M2 reflecting electrode fingers of the quartz substrate 5 may further satisfy:

[0042] N1 / (M1+M2)=1, or 1 / 2≤N1 / (M1+M2)<1, or N1 / (M1+M2)>1.

[0043] Specifically, Figure 7 As shown, the N1 protrusions, M1 transducing electrode fingers, and M2 reflecting electrode fingers of the quartz substrate 5 satisfy: N1 / (M1+M2)=1; Fig. 9 As shown, the N1 protrusions, M1 transducing electrode fingers, and M2 reflecting electrode fingers of the quartz substrate 5 of the elastic wave device 400 satisfy: 1 / 2≤N1 / (M1+M2)<1, as Fig.10 As shown, N1 protrusions, M1 transducing electrode fingers, and M2 reflecting electrode fingers of quartz substrate 5 of elastic wave device 500 satisfy: N1 / (M1+M2)>1.

[0044] like Fig.11 As shown, in the present invention, on the basis that the N1 protrusions, M1 transducing electrode fingers, and M2 reflecting electrode fingers of the quartz substrate 5 satisfy N1 / (M1+M2)≥1 / 2, as the electrode height h of the transducing electrode finger (or reflecting electrode finger) increases, Al The curvature of the slowness curve of the elastic wave device 300 gradually decreases from greater than 0 to less than 0. To ensure that the curvature is less than 0, the thickness h of the aluminum electrode Al Need to meet h Al ≤280nm (7%λ), compared to the thickness h of the aluminum electrode of the elastic wave device 200 in the prior art. Al ≤160nm (4%λ), at this time, under the condition of suppressing the lateral mode of the elastic wave device and the same curvature, the thickness h of the aluminum electrode applied in the present invention is Al The bandgap jitter of the corresponding elastic wave device will be weakened and the ohmic loss will be reduced. That is, compared with the elastic wave device 200, the elastic wave device 300 can suppress the lateral mode of the elastic wave device 300 while reducing the bandgap jitter and the ohmic loss.

[0045] Optionally, the piezoelectric layer 1 is lithium niobate LiNbO3, the Euler angle is (0°, 90°-140°, 0°), the Euler angle of the quartz substrate 5 is (0°, 126°, 0°), and the first height h p =300nm, the second height h t = 120nm, electrode width w = 1μm, height of convex portion h s =180nm, the wavelength of the elastic wave λ=4μm.

[0046] In the present application, on the basis that the N1 protrusions, M1 transducer electrode fingers, and M2 reflective electrode fingers of the quartz substrate 5 satisfy N1 / (M1+M2)≥1 / 2, preferably, N1 / (M1+M2)>1, the electrical layer 1 is lithium niobate LiNbO3, the Euler angle is (0°, 90°~140°, 0°), preferably, the Euler angle is (0°, 122°, 0°), the Euler angle of the quartz substrate 5 can be (0°, 126°, 0°), and the first thickness h p is 300nm, and the second thickness h t is 120nm, the width W of the convex portion is equal to the electrode width w, W = w = 1μm, and the height h of the convex portion is s =180nm, the wavelength λ of the elastic wave is 4μm. p =300nm, the second height h t = 120nm, electrode width w = 1μm, height of convex portion h s =180nm, the partial or overall design of the elastic wave wavelength λ=4μm can enhance the longitudinal mode effect of the elastic wave device 300 compared to the elastic wave device 200, and while effectively suppressing the transverse mode of the elastic wave device, it can achieve reduced bandgap jitter, reduced ohmic loss, enhanced the conductivity of the electrode, ensured good contact and stability of the electrode, avoid unnecessary energy loss and instability of the elastic wave device, and improve the signal transmission performance of the elastic wave device, which is suitable for application in high-frequency miniaturized devices.

[0047] Optionally, along the first direction, the width of the transducing electrode finger and the width of the reflecting electrode finger are equal, both being the electrode width w, and the width of the convex portion 66 is W, satisfying: W≥0.6×w.

[0048] In some embodiments, all the above-mentioned technical contents can be combined according to the needs of technicians, such as Fig.12 As shown, the first height h p is 300nm, and the second height h t is 120nm, and the electrode height h Al is 280nm, and the height of the convex portion h s=180nm, the wavelength λ of the elastic wave is 4μm, and w=1μm. It can be seen from the curve that as the width W of the convex portion increases, the curvature of the slowness curve of the elastic wave device 300 gradually decreases, from greater than 0 to less than 0. To ensure that the curvature is less than 0, the width W of the convex portion needs to satisfy W≥0.6×w.

[0049] Therefore, in the present application, first, at a first height h p , second height h t , electrode height h Al , the height h of the convex part s After the parameters of the wavelength λ of the elastic wave are set, the curvature of the slowness curve is affected as the width W of the convex portion changes, and a design rule of W≥0.6×w is proposed, which can control the propagation characteristics of the elastic wave, help optimize the overall performance indicators of the elastic wave device, and enable it to better process complex signals in the field of high-frequency communications, reduce signal attenuation and distortion, and help improve the directionality and stability of signal transmission; in addition, it can suppress the transverse mode of the elastic wave device, greatly reducing the energy dispersion phenomenon caused by the transverse mode during the propagation of the elastic wave, so that the energy can be more concentratedly propagated along the predetermined direction, thereby improving the efficiency of elastic wave transmission. In filter applications, it can accurately screen out elastic waves of specific frequencies, reduce clutter interference, and improve filtering performance. In the resonator, it can enhance the resonance effect, make the resonant frequency more stable and accurate, and promote the transverse mode suppression technology of the elastic wave device to higher precision and better performance.

[0050] Optionally, along the third direction, the piezoelectric layer comprises a first height h p and the second height h t , the height of the protrusion 66 is h s , satisfying: h p >h t ,h s ≥0.4×h p .

[0051] In some embodiments, all the above-mentioned technical contents can be combined according to the needs of technicians, such as Fig.13 As shown, the first height h p is 300nm, and the electrode height h Al is 280nm, the width W of the convex portion is equal to the electrode width w, W = w = 1μm, and the wavelength λ of the elastic wave is 4μm. It can be seen from the curve that as the height h s As the curvature of the slowness curve of the elastic wave device 300 gradually decreases from greater than 0 to less than 0, to ensure that the curvature is less than 0, the height h of the convex portion s Need to meet h s ≥0.4×h p .

[0052] Therefore, in the present invention, first, as the height h of the convex portion s As the slowness curve of the elastic wave device increases, the curvature of the curve gradually decreases from greater than 0 to less than 0, achieving the purpose of effectively suppressing the transverse mode. In addition, h s ≥0.4×h p The design rules can effectively reduce the influence of the transverse mode of the elastic wave device and enhance the directivity of the elastic wave device, ensure that the longitudinal wave of the elastic wave device is dominant, reduce the energy loss and interference caused by the transverse mode, and enable the elastic wave device to work more accurately and stably in practical applications, thereby improving the performance of the elastic wave device.

[0053] Optionally, the piezoelectric layer 1 is lithium tantalate LiTaO3, the Euler angle is (0°, 100°-150°, 0°), and the Euler angle of the quartz substrate 5 is (0°, 126°, 0°).

[0054] In the present application, firstly, the piezoelectric layer 1 uses lithium tantalate LiTaO3 as the main material. Lithium tantalate is widely used in elastic wave devices due to its excellent piezoelectric properties and high temperature stability. Lithium tantalate has a high piezoelectric constant and a good mechanical quality factor, which makes it have lower loss and higher efficiency in high-frequency applications; the selected Euler angle is (0°, 100°~150°, 0°), preferably, the Euler angle is (0°, 132°, 0°), which provides an optimized crystal orientation for the piezoelectric layer 1 (lithium tantalate) and ensures the best performance of the piezoelectric effect in the device. This angle range setting helps to maximize the longitudinal mode effect of the piezoelectric layer and suppress the occurrence of the transverse mode; in addition, the Euler angle (0°, 126°, 0°) of the quartz substrate 5 ensures that the substrate will not cause the piezoelectric effect during operation. Excessive transverse modal effects, the high quality factor (Q factor) and low electrical loss of quartz help to provide a stable environment, so that the performance of the piezoelectric layer 1 can be better reflected, thereby reducing the energy loss and unnecessary interference of the system; in addition, on the basis of satisfying N1 / (M1+M2)≥1 / 2, preferably, N1 / (M1+M2)>1, the longitudinal mode of the elastic wave device can become the dominant mode, and the energy of the transverse mode can be effectively suppressed, which can ensure that the bandgap jitter is minimized and the ohmic loss is reduced, while making the elastic wave device work efficiently and improving the signal quality and processing speed of the system.

[0055] In a second aspect, the present invention provides a filter, comprising: a series arm resonator and a parallel arm resonator; at least one of the series arm resonator and the parallel arm resonator is the elastic wave device described in any one of the first aspects.

[0056] It should be noted that a filter applied for in the present invention is used to realize an elastic wave device including any one of the first aspects, and accordingly also includes all the recorded technical problems, technical solutions and technical effects of any one of the elastic wave devices in the first aspect, which will not be repeated in the present invention application.

[0057] In the present invention application, the filter of the present invention adopts any elastic wave device in the first aspect by combining a series arm resonator and a parallel arm resonator, and can make the frequency selectivity of the filter more accurate by virtue of its effective control characteristics of elastic waves, such as suppressing the lateral mode. When processing complex signals, unnecessary frequency components can be filtered out to reduce mutual interference between signals; at the same time, whether in different environmental conditions or long-term operation, the filter can always maintain good filtering performance, realize the optimization processing of signal transmission, reduce the loss of signal transmission, and improve the stability and reliability of the filter.

[0058] In a third aspect, the present invention provides a multiplexer, comprising: an antenna terminal connected to an antenna; a plurality of filters connected to the antenna terminal; and at least one filter is the filter in the second aspect.

[0059] It should be noted that a multiplexer applied for in the present invention is used to implement a filter in the second aspect, and accordingly includes all the technical problems, technical solutions and technical effects recorded in a filter in the second aspect, which will not be repeated in the present invention application.

[0060] In the present invention application, firstly, by connecting multiple filters to the antenna terminal, signals of different frequencies can be effectively processed and separated, and at least one filter adopts the filter design in the second aspect, and its superior frequency selectivity, low noise and high stability can be used to greatly improve the signal processing capability of the multiplexer. Through this multi-filter structure, it is possible to support the parallel transmission of multiple signal frequency bands, effectively reduce signal interference and crosstalk, and improve the overall performance of the multiplexer; in addition, the multiplexer adopts the filter in the second aspect, which can achieve more accurate signal separation and optimize spectrum utilization efficiency, thereby meeting the needs of efficient and multi-band transmission in complex communication systems, and is suitable for a variety of wireless communications (such as 2G, 3G, 4G and even 5G signals) and satellite communications. The stability and efficiency of multi-band communications can be guaranteed, and users can be provided with a smoother and richer communication service experience, which greatly promotes the development of wireless communication technology towards multi-band integration, and has good technical and market prospects.

[0061] In the embodiments disclosed in the present application, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments disclosed in the present application can be understood according to specific circumstances.

[0062] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. An elastic wave device, comprising: Piezoelectric layer, quartz substrate and conductive material film pattern; The conductive material film pattern includes an interdigital transducer electrode and a reflector electrode; the interdigital transducer electrode includes M1 transducer electrode fingers, and the reflector electrode includes M2 reflective electrode fingers, and is characterized in that: Along the third direction, the piezoelectric layer is arranged on the quartz substrate, and the conductive material film pattern is arranged on the piezoelectric layer. The third direction is the height direction of the elastic wave device. Along the first direction, the reflector electrode is located on both sides of the interdigital transducer electrode. The piezoelectric layer includes N1 concave portions, and the quartz substrate includes N1 convex portions. The first direction is the arrangement direction of the N1 convex portions. Each convex portion cooperates with two adjacent concave portions to satisfy: N1 / (M1+M2)≥1 / 2.

2. The elastic wave device according to claim 1, wherein: Along the first direction, the width of the transducing electrode finger and the width of the reflecting electrode finger are equal, both being the electrode width w, and the width of the convex portion is W, satisfying W≥0.6×w.

3. The elastic wave device according to claim 1, wherein: Along the third direction, the piezoelectric layer includes a first height h p and the second height h t , the height of the convex part is h s , satisfying: h p >h t ,h s ≥0.4×h p .

4. The elastic wave device according to claim 1, wherein: N1 / (M1+M2)=1, or 1 / 2≤N1 / (M1+M2)<1, or N1 / (M1+M2)>1.

5. The elastic wave device according to claim 1, wherein: The piezoelectric layer is lithium niobate LiNbO3, and the Euler angle is (0°, 90°~140°, 0°).

6. The elastic wave device according to claim 1, wherein: The piezoelectric layer is lithium tantalate LiTaO3, and the Euler angle is (0°, 100°~150°, 0°).

7. A filter comprising: A series arm resonator and a parallel arm resonator, characterized in that: At least one of the series arm resonator and the parallel arm resonator is the elastic wave device according to any one of claims 1 to 6.

8. A multiplexer comprising: An antenna terminal connected to the antenna; Multiple filters, multiple filters are connected to antenna terminals; characterized in that: at least one filter is the filter described in claim 7 above.

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