Elastic wave device, filter or multiplexer having high linearity

Abstract

The invention relates to an elastic wave device with high linearity, a filter or a multiplexer, and belongs to the technical field of elastic waves, the filter or the multiplexer is provided with a series arm resonator and a parallel arm resonator, and the series arm resonator and the parallel arm resonator comprise the elastic wave device. According to the invention, the linearity of the elastic wave device can be improved.

Description

Technical Field

[0001] The present invention application relates to the technical field of elastic wave, and particularly to an elastic wave device, a filter or a multiplexer with high linearity. Background Art

[0002] Elastic wave devices are widely used in the radio frequency front end of mobile communication systems due to their advantages such as high performance, low loss, and small size, and are key devices for signal selection and ensuring communication quality. However, with the rapid increase in the complexity and integration of radio frequency front-end modules, the miniaturization of devices and the improvement of operating power levels have become development trends, and the non-linearity problem of radio frequency devices has become increasingly serious. Under high-power conditions, elastic wave devices will inevitably generate non-linear effects such as harmonics and intermodulation distortion. Therefore, while the International Organization for Standardization has put forward higher requirements for the performance of the radio frequency front end of 5G mobile terminals, it has also set more stringent indicators for the non-linearity level of radio frequency devices. Suppressing the non-linearity of elastic wave devices to improve their own linearity has become an urgent problem to be solved in the industry. Summary of the Invention

[0003] The present invention application provides an elastic wave device, a filter or a multiplexer with high linearity, aiming to partially or fully solve the technical problem of how to suppress the non-linearity of elastic wave devices and improve the linearity of elastic wave devices in the prior art. To achieve the above object, the present invention application adopts the following technical solutions:

[0004] In a first aspect, an elastic wave device includes:

[0005] A silicon substrate layer, a low acoustic velocity layer, and a piezoelectric layer;

[0006] Along a second direction, a low acoustic velocity layer is disposed above the silicon substrate layer, a piezoelectric layer is disposed above the low acoustic velocity layer, and a conductive material thin film pattern is formed above the piezoelectric layer; the conductive material thin film pattern includes an interdigital transducer and a reflector;

[0007] The interdigital transducer includes a plurality of first electrode fingers and a plurality of second electrode fingers that are alternately arranged along a first direction, and a plurality of first electrode dummy fingers and second electrode dummy fingers that are alternately arranged;

[0008] Along the second direction, a first bus bar and a second bus bar are opposed to each other; the starting end portion of the first electrode finger is connected to the first bus bar, the ending end portion of the first electrode finger is spaced and opposed to the ending end portion of the second electrode dummy finger, and the starting portion of the second electrode dummy finger is connected to the second bus bar; the leading end portion of the second electrode finger is connected to the second bus bar, the trailing end portion of the second electrode finger is spaced and opposed to the trailing end portion of the first electrode dummy finger, and the starting portion of the first electrode dummy finger is connected to the first bus bar;

[0009] The end portions of multiple first electrode fingers are connected to form a first connection line, and the tail end portions of multiple second electrode fingers are connected to form a second connection line, satisfying: 8° ≤ θ1 ≤ 16°, 8° ≤ θ2 ≤ 16°, where θ1 is the included angle formed by the extension direction of the first connection line and the first direction, and θ2 is the included angle formed by the extension direction of the second connection line and the first direction.

[0010] Optionally, the piezoelectric layer is lithium niobate, and the Euler angles of the lithium niobate are set to (0°, Φ, 0°), satisfying: 90° ≤ Φ ≤ 150°.

[0011] Optionally, the thickness of the silicon substrate layer is 500 μm, the material of the low acoustic velocity layer is silicon dioxide, along the second direction, the thickness of the low acoustic velocity layer is 825 nm, the thickness of the piezoelectric layer is 850 nm, and the thickness of the conductive material thin film pattern is 300 nm; the piezoelectric layer is 30° Y-cut lithium niobate, and the Euler angle is (0°, 120°, 0°); the wavelength λ of the elastic wave is 4 μm, and the material of the conductive material thin film pattern is aluminum.

[0012] Optionally, θ1 = θ2.

[0013] In a second aspect, a filter or multiplexer has series arm resonators and shunt arm resonators, where: the series arm resonators and the shunt arm resonators include any one of the elastic wave devices in the first aspect above.

[0014] In summary, the present invention application has the following beneficial technical effects:

[0015] (1) In the present invention application, first, the silicon substrate layer is selected for the elastic wave device. Compared with the 4H-silicon carbide substrate layer, the third harmonic amplitude of the elastic wave device is reduced by nearly 10 dB, and its own linearity is greatly improved; in addition, the included angle θ1 formed by the extension direction of the first connection line of the elastic wave device and the first direction, and the included angle θ2 formed by the extension direction of the second connection line and the first direction, satisfy: 8°

[0016] ≤ θ1 ≤ 16°, 8° ≤ θ2 ≤ 16°, the third harmonic amplitude of the elastic wave device is reduced by nearly 10 dB, and its own linearity is greatly improved.

[0017] (2) In the present invention application, by selecting a silicon substrate layer for the elastic wave device, the included angle θ1 (8° ≤ θ1 ≤ 16°) formed by the extension direction of the first connection line intersecting with the first direction, and the included angle θ2 (8° ≤ θ2 ≤ 16°) formed by the extension direction of the second connection line intersecting with the first direction are set in coordination. The combined effect of the silicon substrate layer and the included angles θ1 and θ2 jointly regulates the acoustic wave propagation through material properties and structural optimization. The settings of the included angles θ1 and θ2 optimize the boundary conditions of the acoustic wave through geometric effects, weaken the generation of non-linear harmonics, jointly suppress the non-linearity of the elastic wave device, and appropriately improve the linearity of the elastic wave device itself.

[0018] Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of an elastic wave device 500 according to an embodiment of the present invention application;

[0020] Figure 2 is a comparison diagram of the third harmonic amplitude-frequency test curves of the elastic wave device 500 when θ is 8° (corresponding to T8), 12° (corresponding to T12), and 16° (corresponding to T16) respectively according to an embodiment of the present invention application;

[0021] Figure 3 is a schematic structural diagram of an elastic wave device 300 in Comparative Example 1 of the present invention application;

[0022] Figure 4 is a schematic structural diagram of an elastic wave device 400 in Comparative Example 2 of the present invention application;

[0023] Figure 5 is a comparison diagram of the third harmonic amplitude-frequency test curves of the elastic wave device 300 in Comparative Example 1 of the present invention application;

[0024] Figure 6 is a comparison diagram of the third harmonic amplitude-frequency test curves of the elastic wave device 400 in Comparative Example 2 of the present invention application. Detailed Embodiments

[0025] In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention application. However, it is obvious to those skilled in the art that the present invention application can be implemented without one or more of these details. In other examples, some well-known technical features are not described to avoid confusion with the present invention application.

[0026] In a first aspect, as Figure 1As shown in the figure, the present invention application provides an elastic wave device 500, including: a silicon substrate layer 14, a low sound velocity layer 12, and a piezoelectric layer 11; along a second direction, the low sound velocity layer 12 is disposed above the silicon substrate layer 14, the piezoelectric layer 11 is disposed above the low sound velocity layer 12, and a conductive material thin film pattern is formed above the piezoelectric layer 11; the conductive material thin film pattern includes an interdigital transducer and a reflector 5; the interdigital transducer includes a plurality of first electrode fingers 2a and a plurality of second electrode fingers 2b that are alternately arranged along a first direction, and a plurality of first dummy electrode fingers 3a and second dummy electrode fingers 3b that are alternately arranged; along the second direction, a first bus bar 4a and a second bus bar 4b are opposed to each other; the starting end portion 2aa of the first electrode finger 2a is connected to the first bus bar 4a, the ending end portion 2ab of the first electrode finger 2a is spaced and opposed to the ending end portion 3bb of the second dummy electrode finger 3b, and the starting portion 3ba of the second dummy electrode finger 3b is connected to the second bus bar 4b; the leading end portion 2ba of the second electrode finger 2b is connected to the second bus bar 4b, the trailing end portion 2bb of the second electrode finger 2b is spaced and opposed to the trailing end portion 3ab of the first dummy electrode finger 3a, and the starting portion 3aa of the first dummy electrode finger 3a is connected to the first bus bar 4a; the ending end portions 2ab of the plurality of first electrode fingers are connected to form a first connection line 5a, the trailing end portions 2bb of the plurality of second electrode fingers are connected to form a second connection line 5b, satisfying: 8° ≤ θ1 ≤ 16°, 8° ≤ θ2 ≤ 16°, where θ1 is the angle formed by the extension direction of the first connection line and the first direction, and θ2 is the angle formed by the extension direction of the second connection line and the first direction.

[0027] In some embodiments, the silicon substrate layer 14 serves as a support substrate, the low sound velocity layer 12 is formed above the silicon substrate layer 14, the low sound velocity layer 12 supports the piezoelectric layer 11, and the Euler angles of the piezoelectric layer 11 are set to (0°, Φ, 0°), where Φ satisfies 90° ≤ Φ ≤ 150°.

[0028] In some embodiments, the first direction may be the arrangement direction of the first electrode finger 1 or the second electrode finger 2, the first direction may also be the x-axis direction, the x-axis direction is also the elastic wave propagation direction, the second direction may be the extension direction of the first electrode finger 1 or the second electrode finger 2, the second direction may also be the y-axis direction, the third direction may be the height direction of the elastic wave device, the third direction may also be the z-axis direction, the first direction, the second direction, and the third direction intersect pairwise, preferably, the first direction, the second direction, and the third direction are perpendicular to each other pairwise.

[0029] Optionally, the thickness of the silicon substrate layer 14 is 500 μm, the material of the low acoustic velocity layer 12 is silicon dioxide, along the second direction, the thickness of the low acoustic velocity layer 12 is 825 nm, the thickness of the piezoelectric layer 11 is 850 nm, and the thickness of the conductive material thin film pattern is 300 nm; the piezoelectric layer 11 is 30° Y-cut lithium niobate, and the Euler angles are (0°, 120°, 0°); the wavelength λ of the elastic wave is 4 μm, and the material of the conductive material thin film pattern is aluminum.

[0030] In the application of the present invention, through comparison with subsequent test results, it can be seen that: First, when the elastic wave device selects a silicon substrate layer, compared with a 4H-silicon carbide substrate layer, the third harmonic amplitude of the elastic wave device is reduced by nearly 10 dB, and its own linearity is greatly improved; in addition, the included angle θ1 formed by the extension direction of the first connection line of the elastic wave device and the first direction, and the included angle θ2 formed by the extension direction of the second connection line and the first direction satisfy: 8° ≤ θ1 ≤ 16°, 8° ≤ θ2 ≤ 16°, and the third harmonic amplitude of the elastic wave device is reduced by nearly 10 dB, and its own linearity is greatly improved; furthermore, through the collaborative setting of the elastic wave device selecting a silicon substrate layer, the included angle θ1 (8° ≤ θ1 ≤ 16°) formed by the extension direction of the first connection line and the first direction, and the included angle θ2 (8° ≤ θ2 ≤ 16°) formed by the extension direction of the second connection line and the first direction, the synergistic effect of the silicon substrate layer and the included angles θ1 and θ2 jointly regulates the acoustic wave propagation through material characteristics and structural optimization. The setting of the included angles θ1 and θ2 optimizes the boundary conditions of the acoustic wave through geometric effects, weakens the generation of non-linear harmonics, forms a "dual suppression", jointly suppresses the non-linearity of the elastic wave device, and appropriately improves the linearity of the elastic wave device itself.

[0031] In a second aspect, a filter or multiplexer has series-arm resonators and shunt-arm resonators, wherein: the series-arm resonators and the shunt-arm resonators each include any one of the elastic wave devices in the first aspect.

[0032] In some embodiments, a filter or multiplexer has series-arm resonators and shunt-arm resonators, wherein: the series-arm resonators and the shunt-arm resonators each include any one of the elastic wave devices in the first aspect.

[0033] (1) Comparative Example 1

[0034] As Figure 3As shown, a cross-sectional view of the elastic wave device 300, the elastic wave device 300 includes: a 4H-silicon carbide substrate layer 13, a low acoustic velocity layer 12, and a piezoelectric layer 11; along the second direction, the low acoustic velocity layer 12 is disposed above the silicon substrate layer 14, the piezoelectric layer 11 is disposed above the low acoustic velocity layer 12, and a conductive material thin film pattern is formed above the piezoelectric layer 11; the conductive material thin film pattern includes an interdigital transducer and a reflector 5; the interdigital transducer includes a plurality of first electrode fingers 2a and a plurality of second electrode fingers 2b that are alternately arranged along the first direction and a plurality of first dummy electrode fingers 3a and second dummy electrode fingers 3b that are alternately arranged; along the second direction, a first bus bar 4a and a second bus bar 4b are opposed to each other; the starting end 2aa of the first electrode finger 2a is connected to the first bus bar 4a, the ending end 2ab of the first electrode finger 2a is spaced and opposed to the ending end 3bb of the second dummy electrode finger 3b, and the starting part 3ba of the second dummy electrode finger 3b is connected to the second bus bar 4b; the leading end 2ba of the second electrode finger 2b is connected to the second bus bar 4b, the trailing end 2bb of the second electrode finger 2b is spaced and opposed to the trailing end 3ab of the first dummy electrode finger 3a, and the starting part 3aa of the first dummy electrode finger 3a is connected to the first bus bar 4a; the ending ends 2ab of the plurality of first electrode fingers are connected to form a first connection line 5a, the trailing ends 2bb of the plurality of second electrode fingers are connected to form a second connection line 5b, satisfying: θ1 = θ2 = 16°, θ1 is the included angle formed by the extending direction of the first connection line and the first direction, and θ2 is the included angle formed by the extending direction of the second connection line and the first direction.

[0035] Specifically, the thickness of the 4H-silicon carbide substrate layer 13 is 500 μm, the material of the low acoustic velocity layer 12 is silicon dioxide, along the second direction, the thickness of the low acoustic velocity layer 12 is 825 nm, the thickness of the piezoelectric layer 11 is 850 nm, and the thickness of the conductive material thin film pattern is 300 nm; the piezoelectric layer 11 is 30° Y-cut lithium niobate with Euler angles of (0°, 120°, 0°); the wavelength λ of the elastic wave is 4 μm, and the material of the conductive material thin film pattern is aluminum. Thus, the difference between Comparative Example 1 and the embodiment of the present invention application is that: when θ1 = θ2 = 16°, 4H-silicon carbide substrate layer 13 is selected in Comparative Example 1.

[0036] (2) Comparative Example 2

[0037] As Figure 4As shown, a cross-sectional view of the elastic wave device 400. The elastic wave device 400 includes: a silicon substrate layer 14, a low acoustic velocity layer 12, and a piezoelectric layer 11. Along the second direction, the low acoustic velocity layer 12 is disposed above the silicon substrate layer 14, the piezoelectric layer 11 is disposed above the low acoustic velocity layer 12, and a conductive material thin film pattern is formed above the piezoelectric layer 11. The conductive material thin film pattern includes an interdigital transducer and a reflector 5. The interdigital transducer includes a plurality of first electrode fingers 2a and a plurality of second electrode fingers 2b that are alternately arranged along the first direction, and a plurality of first dummy electrode fingers 3a and second dummy electrode fingers 3b that are alternately arranged. Along the second direction, a first bus bar 4a and a second bus bar 4b are opposed to each other. The starting end 2aa of the first electrode finger 2a is connected to the first bus bar 4a, the ending end 2ab of the first electrode finger 2a is spaced and opposed to the ending end 3bb of the second dummy electrode finger 3b, and the starting end 3ba of the second dummy electrode finger 3b is connected to the second bus bar 4b. The leading end 2ba of the second electrode finger 2b is connected to the second bus bar 4b, the trailing end 2bb of the second electrode finger 2b is spaced and opposed to the trailing end 3ab of the first dummy electrode finger 3a, and the starting end 3aa of the first dummy electrode finger 3a is connected to the first bus bar 4a. The ending ends 2ab of the plurality of first electrode fingers are connected to form a first connection line 5a, and the trailing ends 2bb of the plurality of second electrode fingers are connected to form a second connection line 5b, satisfying: θ1 = θ2 = 0°, where θ1 is the angle formed by the extension direction of the first connection line and the first direction, and θ2 is the angle formed by the extension direction of the second connection line and the first direction.

[0038] Specifically, the thickness of the silicon substrate layer 14 is 500 μm, the material of the low acoustic velocity layer 12 is silicon dioxide, along the second direction, the thickness of the low acoustic velocity layer 12 is 825 nm, the thickness of the piezoelectric layer 11 is 850 nm, and the thickness of the conductive material thin film pattern is 300 nm. The piezoelectric layer 11 is 30° Y-cut lithium niobate with Euler angles of (0°, 120°, 0°). The wavelength λ of the elastic wave is 4 μm, and the material of the conductive material thin film pattern is aluminum. Thus, the difference between Comparative Example 2 and the embodiment of the present invention application is that in Comparative Example 2, θ1 = θ2 = 0°.

[0039] (3) Comparison of test results

[0040] As Figure 2 shown, when θ is 8°, 12°, and 16° respectively, a comparison graph of the third harmonic amplitude-frequency test curves of the elastic wave device 500. It can be seen from the curves that the maximum value of the third harmonic amplitude of the elastic wave device 500 is below the -60 dBm level.

[0041] As Figure 5 shown, the third harmonic amplitude-frequency test curve graph of the elastic wave device 300 in Comparative Example 1. It can be seen from the curves that the highest third harmonic amplitude of the elastic wave device 300 reaches -50 dBm.

[0042] like Figure 6 As shown, the third harmonic amplitude-frequency test curve of the elastic wave device 400 in comparative example 2. From the curve, it can be seen that the third harmonic amplitude of the elastic wave device 400 reaches -50dBm at most.

[0043] From this, we can see that:

[0044] 1) By comparing Comparative Example 1 with the elastic wave device 500 of the present invention, it can be seen that the maximum amplitude of the third harmonic of the elastic wave device 500 is below the level of -60 dBm. Compared with the elastic wave device 300, after the silicon substrate layer 14 is selected, the amplitude of the third harmonic of the elastic wave device 500 is weakened by nearly 10 dB, and its own linearity is greatly improved;

[0045] 2) By comparing Comparative Example 2 with the elastic wave device 500 of the present invention, it can be seen that the maximum amplitude of the third harmonic of the elastic wave device 500 is below -60 dBm. Compared with the elastic wave device 400, after changing the setting of the angle θ, the amplitude of the third harmonic of the elastic wave device 500 is reduced by nearly 10 dB, and its own linearity is greatly improved.

[0046] 3) By comparing comparative examples 1 and 2 with the elastic wave device 500 of the present invention, it can be seen that the maximum value of the third harmonic amplitude of the elastic wave device 500 is below the level of -60Bm. Compared with the elastic wave device 300 and the elastic wave device 400, the third harmonic amplitude of the elastic wave device 500 is weakened by nearly 10dB, and its own linearity is greatly improved.

[0047] The above is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

[0048] As mentioned above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be interpreted as limiting the present invention itself. Various changes can be made to it in form and detail without departing from the spirit and scope of the present invention defined in the appended claims.

Claims

1. An elastic wave device, characterized in that: include: Silicon substrate layer, low acoustic velocity layer, piezoelectric layer; Along the second direction, a low acoustic velocity layer is arranged above the silicon substrate layer, a piezoelectric layer is arranged above the low acoustic velocity layer, and a conductive material film pattern is formed above the piezoelectric layer; the conductive material film pattern includes an interdigital transducer and a reflector; The interdigital transducer comprises a plurality of first electrode fingers and a plurality of second electrode fingers arranged alternately with each other along a first direction, and a plurality of first electrode dummy fingers and a plurality of second electrode dummy fingers arranged alternately with each other; Along the second direction, the first bus bar and the second bus bar are opposite to each other; the starting end of the first electrode finger is connected to the first bus bar, the end of the first electrode finger is spaced and opposite to the end of the second electrode finger, and the starting part of the second electrode finger is connected to the second bus bar; the leading end of the second electrode finger is connected to the second bus bar, the tail end of the second electrode finger is spaced and opposite to the tail end of the first electrode finger, and the starting part of the first electrode finger is connected to the first bus bar; The end portions of a plurality of first electrode fingers are connected to form a first connection line, and the tail ends of a plurality of second electrode fingers are connected to form a second connection line, satisfying: 8°≤θ1≤16°, 8°≤θ2≤16°, θ1 is an angle formed by the intersection of the extension direction of the first connection line and the first direction, and θ2 is an angle formed by the intersection of the extension direction of the second connection line and the first direction.

2. The elastic wave device according to claim 1, wherein: The piezoelectric layer is lithium niobate, and the Euler angle of the lithium niobate is set to (0°, Φ, 0°), satisfying: 90°≤Φ≤150°.

3. The elastic wave device according to claim 1, wherein: The thickness of the silicon substrate layer is 500μm, the material of the low acoustic velocity layer is silicon dioxide, along the second direction, the thickness of the low acoustic velocity layer is 825nm, the thickness of the piezoelectric layer is 850nm, and the thickness of the conductive material thin film pattern is 300nm; the piezoelectric layer is 30°Y-cut lithium niobate, and the Euler angle is (0°, 120°, 0°); the wavelength λ of the elastic wave is 4μm, and the material of the conductive material thin film pattern is aluminum.

4. The elastic wave device according to claim 1, wherein: θ1=θ2.

5. A filter or multiplexer having a series arm resonator and a parallel arm resonator, wherein: The series arm resonator and the parallel arm resonator include the elastic wave device according to any one of claims 1 to 4.

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