An elastic wave device and method of manufacture, electronic module

Abstract

The application discloses an elastic wave device and a manufacturing method and an electronic module, wherein the elastic wave device comprises a support substrate, a piezoelectric substrate and a plurality of interdigital electrodes, the piezoelectric substrate is bonded with the support substrate, a surface of the piezoelectric substrate away from the support substrate has a damage layer, and the thickness of the damage layer is less than 0.00075 lambda; the plurality of interdigital electrodes are arranged at intervals on the side of the piezoelectric substrate away from the support substrate, and the interval between two adjacent interdigital electrodes is less than 3 microns; that is, the thickness of the damage layer can be effectively reduced in the application, the insertion loss generated by the filter is reduced, the frequency concentration is improved, and the electrical performance of subsequent products is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic device processing and manufacturing, in particular to an elastic wave device, a manufacturing method thereof and an electronic module. BACKGROUND

[0002] The elastic wave device is included in a filter structure, and the thickness of the piezoelectric layer determines the center frequency range of the filter. A high-frequency filter represents a thinner piezoelectric layer, which also leads to a more serious frequency deviation caused by the same size error. Therefore, it is desirable to obtain a piezoelectric layer with smaller thickness fluctuation to ensure that the center frequency of the filter is in the target center.

[0003] In the prior art, the thickness range of the piezoelectric substrate of the composite substrate is controlled by etching technology, but the existing etching technology generates a relatively thick damage layer on the surface of the piezoelectric substrate, which causes a large insertion loss of the filter, thereby affecting the electrical performance of the filter. SUMMARY

[0004] The technical problem solved by the present application is to provide an elastic wave device, a manufacturing method thereof and an electronic module, which can effectively reduce the thickness of the damage layer, reduce the insertion loss of the filter, and improve the electrical performance of the filter.

[0005] To solve the above technical problems, one technical solution adopted by the present application is to provide an elastic wave device, comprising a support substrate, a piezoelectric substrate and a plurality of interdigital electrodes, the piezoelectric substrate is bonded to the support substrate, the surface of the piezoelectric substrate away from the support substrate has a damage layer, the thickness of the damage layer is less than 0.00075λ; the plurality of interdigital electrodes are arranged at intervals on the side of the piezoelectric substrate away from the support substrate, and the spacing between the adjacent two interdigital electrodes is less than 3μm.

[0006] To solve the above technical problems, another technical solution adopted by the present application is to provide a manufacturing method of an elastic wave device, comprising the following steps: providing a support substrate; bonding a piezoelectric substrate on the support substrate; etching the piezoelectric substrate by using an ion beam to form a composite substrate, wherein a damage layer is formed on the surface of the piezoelectric substrate away from the support substrate, and the thickness of the damage layer is less than 0.00075λ; forming a plurality of interdigital electrodes arranged at intervals on the piezoelectric substrate, and the spacing between the adjacent two interdigital electrodes is less than 3μm.

[0007] To solve the above technical problems, still another technical solution adopted by the present application is to provide an electronic module comprising the above-mentioned elastic wave device.

[0008] Different from the prior art, the elastic wave device provided in the application comprises a bonded support substrate and a piezoelectric substrate, wherein the piezoelectric substrate has a damage layer away from the surface of the support substrate, and the thickness of the damage layer is less than 0.00075λ; a plurality of interdigital electrodes are arranged at the side of the piezoelectric substrate away from the support substrate, and the spacing between two adjacent interdigital electrodes is less than 3μm; the thickness of the damage layer can be effectively reduced, the insertion loss generated by the filter can be reduced, the frequency concentration of the filter can be improved, and the electrical properties of the subsequent product are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort. Among them:

[0010] Figure 1 is a structural schematic diagram of a first embodiment of a composite substrate in the application;

[0011] Figure 2 is a structural schematic diagram of a second embodiment of a composite substrate in the application;

[0012] Figure 3 is a structural schematic diagram of a third embodiment of a composite substrate in the application;

[0013] Figure 4 is a flowchart of a first embodiment of a preparation method of a composite substrate in the application;

[0014] Figure 5 is a filter characteristic comparison diagram;

[0015] Figure 6 is a structural schematic diagram of a first embodiment of a filter in the application;

[0016] Figure 7 is a structural schematic diagram of a second embodiment of a filter in the application.

[0017] In the drawings, filter 1, elastic wave device 10, support substrate 100, substrate 110, support layer 120, first support layer 121, second support layer 122, piezoelectric substrate 200, damage layer 210, piezoelectric layer 220, interdigital electrode 300. DETAILED DESCRIPTION

[0018] With reference to the drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. It can be understood that the specific embodiments described here are only used to explain the present application, but not to limit the present application. In addition, it should be explained that, in order to facilitate the description, only the parts related to the present application are shown in the drawings, but not all the structures. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0019] The term "embodiment" mentioned in the application means that the specific features, structures or characteristics described in combination with the embodiment can be contained in at least one embodiment of the present application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] The terms "first", "second", etc. in the present application are used to distinguish different objects, not to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units not listed or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0021] In addition, although the terms "first", "second" and the like are used repeatedly in the present application to describe various data (or various elements or various applications or various instructions or various operations) and the like, these data (or elements or applications or instructions or operations) should not be limited by these terms. These terms are only used to distinguish one data (or element or application or instruction or operation) from another data (or element or application or instruction or operation). For example, the first position information can be referred to as the second position information, and the second position information can also be referred to as the first position information, only the scope included by the two is different, without departing from the scope of the present application, the first position information and the second position information are both a set of various position and attitude information, only the two are not the same set of position and attitude information.

[0022] In the filter structure, the thickness of the piezoelectric layer determines the center frequency range of the filter. High frequency filters represent thinner piezoelectric layers, which also result in more serious frequency deviation caused by the same size error. Therefore, it is desirable to obtain a piezoelectric layer with less thickness fluctuation to ensure that the center frequency of the filter is in the target center. In addition, during the preparation of the composite substrate of the filter, it is usually prepared by bonding, thinning and polishing. However, due to process stability and different support substrate topography, the piezoelectric substrate after bonding may have different thicknesses, and it is difficult to control the uniformity of the piezoelectric substrate thickness, so that the frequency concentration of the filter prepared based on the composite substrate is low, which affects the frequency range of the filter and reduces the yield; in the prior art, the thickness range of the piezoelectric substrate of the composite substrate is controlled by etching technology, but the existing etching technology will generate a relatively thick damage layer on the surface of the piezoelectric substrate, which will cause a large insertion loss of the filter, and thus affect the electrical performance of the filter.

[0023] Therefore, an elastic wave device and a preparation method and an electronic module based on the elastic wave device, such as a surface acoustic wave filter, are proposed. The elastic wave device of the present application can effectively reduce the thickness of the damage layer, reduce the insertion loss generated by the filter, and thus improve the frequency concentration of the filter, thereby ensuring the electrical properties of the subsequent product.

[0024] Please refer to Figure 1 , Figure 1 is a structural schematic diagram of the first embodiment of the elastic wave device in the present application.

[0025] As Figure 1 indicated, the elastic wave device 10 includes a support substrate 100, a piezoelectric substrate 200 and a plurality of interdigital electrodes 300; the piezoelectric substrate 200 is bonded to the support substrate 100, the surface of the piezoelectric substrate 200 away from the support substrate 100 has a damage layer 210, the thickness of the damage layer 210 is less than 0.00075λ, a plurality of interdigital electrodes 300 are arranged on the side of the piezoelectric substrate 200 away from the support substrate 100, the distance between two adjacent interdigital electrodes 300 is less than 3μm, wherein λ is the wavelength of the elastic wave of the elastic wave device 10, which is determined according to the electrode period of the interdigital electrode 300.

[0026] Among them, the support substrate 100 is the bottom plate supporting the entire device, and the piezoelectric substrate is a crystal material that will generate a voltage between the two end faces when subjected to pressure.

[0027] Specifically, the support substrate 100 has a first surface, the piezoelectric substrate 200 has an opposite second surface and a third surface, for example, the bottom surface of the piezoelectric substrate 200 is the second surface, and the top surface of the piezoelectric substrate 200 is the third surface; the support substrate 100 takes the first surface as the bonding surface of the support substrate 100, and the piezoelectric substrate 200 takes the second surface as the bonding surface of the piezoelectric substrate 200, so that the support substrate 100 is bonded to the second surface of the piezoelectric substrate 200 through the first surface; in addition, the surface of the piezoelectric substrate 200 away from the support substrate 100 has a damage layer 210, the thickness of the damage layer 210 is less than 0.00075λ; a plurality of interdigital electrodes 300 are arranged at intervals on the side of the piezoelectric substrate 200 away from the support substrate 100, and the distance between two adjacent interdigital electrodes 300 is less than 3μm; wherein λ is the wavelength of the elastic wave of the elastic wave device 10, which is determined according to the electrode period of the interdigital electrode 300.

[0028] The elastic wave is a kind of stress wave, and the stress wave is a propagation form of stress and strain disturbance, that is, the form of stress and strain caused by disturbance or external force in the elastic wave device 10; there is an elastic force between the particles in the elastic wave device 10. After a particle deviates from the equilibrium position due to the disturbance or external force, the elastic restoring force makes the particle vibrate, thereby causing the displacement and vibration of the surrounding particles, so that the vibration propagates in the elastic medium and is accompanied by energy transmission. Where the vibration is, the stress and strain will change.

[0029] In this embodiment, in order to reduce the insertion loss generated by the subsequent filter, the thickness of the damage layer in the piezoelectric substrate is set to be less than 0.00075λ, while ensuring the thickness uniformity of the piezoelectric substrate 200, so as to achieve the required frequency concentration of the filter formed based on the composite substrate.

[0030] Referring to Figure 2 , Figure 2 , the second embodiment of the composite substrate in this application is a structural schematic diagram.

[0031] As Figure 2 shown, the elastic wave device 10 includes a support substrate 100, a piezoelectric substrate 200 and a plurality of interdigital electrodes 300; wherein the piezoelectric substrate 200 is bonded to the support substrate 100, the surface of the piezoelectric substrate 200 away from the support substrate 100 has a damage layer 210, the thickness of the damage layer 210 is less than 0.00075λ, a plurality of interdigital electrodes 300 are arranged at intervals on the side of the piezoelectric substrate 200 away from the support substrate 100, and the distance between two adjacent interdigital electrodes 300 is less than 3μm, wherein λ is the wavelength of the elastic wave of the elastic wave device 10, which is determined according to the electrode period of the interdigital electrode 300.

[0032] The electrode period of the interdigital electrode 300 is determined according to four structure parameters of the interdigital electrode structure, including the logarithm of the interdigital electrode pair, the interdigital width, the spacing between adjacent interdigital electrodes, and the thickness of the interdigital electrode. Through analysis of the calculation formula of the resistance of the interdigital electrode, it can be found that the greater the aspect ratio of the interdigital electrode, the greater the density of the interdigital electrode, and the smaller the initial resistance of the interdigital electrode, so that the sensitivity and response speed of the sensor will be higher. When the size of the interdigital electrode structure is reduced to the micron level, the weak resistance change between the interdigital electrode structures can be sensitively detected, and the sensitivity of the interdigital electrode sensor is significantly improved. The electric field distribution around the interdigital electrode structure can be obtained by theoretical analysis and numerical simulation calculation, and the calculation results show that the electric field strength of the interdigital electrode sensor is approximately inversely proportional to the electrode thickness, and the thicker the electrode, the smaller the electric field strength. In addition, the logarithm of the electrode has little effect on the signal-to-noise ratio of the interdigital electrode sensor; the reduction of the interdigital electrode spacing can increase the signal-to-noise ratio while improving the signal amplitude; the reduction of the interdigital electrode spacing can also effectively improve the reaction rate and speed up the reaction process, thereby improving the performance of the sensor and shortening the reaction time of the interdigital electrode sensor. The reduction of the electrode width of the interdigital electrode sensor can improve the signal-to-noise ratio while reducing the detection signal amplitude.

[0033] In some embodiments, the support substrate 100 can include a substrate 110 and at least one support layer 120, and the bonding surface of the support substrate 100 can be a horizontal surface or a curved surface; the bonding surface of the piezoelectric substrate 200 is arranged correspondingly to the bonding surface of the support substrate 100, so that the support substrate 100 and the piezoelectric substrate 200 are bonded with the corresponding bonding surfaces.

[0034] Specifically, the bonding surface of the support substrate 100 is taken as a horizontal surface, and the support layer 120 includes a first support layer 121 and a second support layer 122, the first support layer 121 is closest to the substrate 110, and the second support layer 122 is farthest from the substrate 110; the first support layer 121 covers the substrate 110, i.e., the first support layer 121 is located between the substrate 110 and the piezoelectric substrate 200; the second support layer 122 covers the first support layer 121, i.e., the second support layer 122 is located between the first support layer 121 and the piezoelectric substrate 200, and the piezoelectric substrate 200 is bonded with the second support layer 122; wherein the piezoelectric substrate 200 includes a piezoelectric layer 220 and a damage layer 210; that is, the piezoelectric layer 220 is bonded with the second support layer 122, and the damage layer 210 covers the piezoelectric layer 220; the thickness of the first support layer 121 is greater than the thickness of the damage layer 210, and the thickness of the second support layer 122 is greater than the thickness of the damage layer 300.

[0035] The substrate 110 can be any suitable substrate known in the art, such as at least one of the following: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors, including multilayer structures of these semiconductors, etc., or silicon-on-insulator (SOI), silicon-on-silicon-on-insulator (SSOI), silicon germanium-on-silicon-on-insulator (S-SiGeOI), silicon germanium-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), or high-resistivity silicon, sapphire, spinel, and polycrystalline materials, etc.

[0036] The first support layer 121 can be at least one of the following or a combination of two or more thereof: silicon oxide, silicon nitride, aluminum oxide, etc., and the thickness of the first support layer 121 is less than 2λ, where λ is the wavelength; for example, when λ is 4 μιη (4000 nm), 0.00025λ can be 1 nm, i.e., the thickness of the first support layer 121 is less than 8000 nm, for example, the thickness of the first support layer 121 is 6000 nm, 6400 nm, or 7000 nm.

[0037] The second support layer 122 can be at least one of the following: titanium, tungsten, silicon, etc., and the thickness of the second support layer 122 is less than 0.004λ when λ is 4 μιη (4000 nm), i.e., the thickness of the second support layer 122 is less than 16 nm, for example, the thickness of the second support layer 122 is 10 nm, 12 nm, or 14 nm.

[0038] The piezoelectric substrate 200 can be a piezoelectric single crystal or a piezoelectric polycrystal, and can be at least one of the following: barium titanate (BT), lead zirconate titanate (PZT), modified lead zirconate titanate, lead metaniobate, lead barium lithium niobate (PBLN), modified lead titanate (PT), quartz (quartz crystal), lithium gallate, lithium germanate, titanium germanate, and ferroelectric lithium niobate, lithium tantalate, etc.; the thickness of the piezoelectric substrate 200 is less than 1λ, i.e., the thickness of the piezoelectric substrate 200 is less than 4000 nm, for example, the thickness of the piezoelectric substrate is 500 nm, 1000 nm, or 2000 nm; and the thickness of the damage layer 210 is less than 0.00075λ, i.e., the thickness of the damage layer 210 is less than 3 nm, for example, the thickness of the damage layer 210 is 1 nm, 0.8 nm, or 0.5 nm.

[0039] In some embodiments, the piezoelectric substrate 200 is configured such that the difference between the maximum and minimum values of the thickness of the piezoelectric substrate 200 is less than 40 nm, so that the thickness uniformity of the piezoelectric substrate 200 is included regardless of the topography of the support substrate 100.

[0040] In the embodiment, the difference between the maximum and minimum thickness of the piezoelectric substrate 200 is controlled to be less than 40 nm when the topography of the support substrate 100 is different, and the thickness uniformity of the piezoelectric substrate 200 is ensured to achieve the required frequency concentration of the filter formed based on the composite substrate; in addition, the damage layer 210 on the side of the piezoelectric substrate 200 away from the support substrate 100 is controlled to be less than 3 nm, so that the frequency concentration is improved while reducing the abnormal insertion loss caused by the damage layer, thereby improving the electrical performance of the subsequently formed device.

[0041] Referring to Figure 3 , Figure 3 FIG. 3 is a structural schematic diagram of a third embodiment of the composite substrate in the present application.

[0042] As Figure 3 shown, the composite substrate 10 includes a support substrate 100, a piezoelectric substrate 200, and a plurality of interdigital electrodes 300; wherein the piezoelectric substrate 200 is bonded to the support substrate 100, and the difference between the maximum and minimum thickness of the piezoelectric substrate 200 is less than 40 nm; the surface of the piezoelectric substrate 200 away from the support substrate 100 has a damage layer 210, that is, the damage layer 210 is located on the side of the piezoelectric substrate 200 away from the support substrate 100, and the thickness of the damage layer 300 is less than 0.00075λ. Wherein, the piezoelectric substrate 200 includes a piezoelectric layer 220 and a damage layer 210.

[0043] That is, the thickness of the damage layer 300 is less than 3 nm, for example, the thickness of the damage layer 210 is 1 nm, 0.8 nm or 0.5 nm.

[0044] Wherein, the bonding surface of the support substrate 100 can be a non-perfect horizontal surface with ups and downs, such as a curved surface, an arc surface, etc., and the support substrate 100 is tightly connected with the piezoelectric substrate 200 after bonding, therefore, the bonding surface of the piezoelectric substrate 200 can also be an arc surface, for example, the bonding surface of the support substrate 100 is an outer arc surface, and the bonding surface of the piezoelectric substrate is an inner arc surface.

[0045] In addition, because the difference between the maximum and minimum thickness of the piezoelectric substrate 200 is less than 40 nm, the surface of the piezoelectric substrate 200 away from the support substrate 100 is also an outer arc surface; for example, the bonding surface of the piezoelectric substrate 200 is parallel to the outer arc surface away from the support substrate 100.

[0046] Correspondingly, the damage layer 210 generated after the piezoelectric substrate 200 is etched by an ion beam is also arc-shaped and covers the surface of the piezoelectric substrate 200.

[0047] In the embodiment, because the bonding surface of the support substrate 100 is a curved surface, the conventional thinning and polishing process cannot make the thickness of the piezoelectric substrate 200 uniform, that is, the difference between the maximum and minimum thickness of the piezoelectric substrate 200 after the thinning and polishing process is large, reaching 0.4 μm, which affects the frequency concentration of the filter; in the embodiment, the ion beam is used to etch the piezoelectric substrate 200, which can effectively reduce the difference between the maximum and minimum thickness of the piezoelectric substrate 200 to less than 40 nm, and the thickness of the damage layer 210 is less than 3 nm, reducing the abnormal insertion loss caused by the damage layer, improving the frequency concentration of the filter, and ensuring the electrical properties of the filter.

[0048] The embodiment also includes a preparation method of a composite substrate, which is specifically as follows.

[0049] Referring to Figure 4 , Figure 4 is a flowchart of an embodiment of the preparation method of the composite substrate in the application.

[0050] As Figure 4 shown, the method includes the following steps:

[0051] S10, providing a support substrate.

[0052] The support substrate 100 can include a substrate 110 and at least one support layer 120, and the bonding surface of the support substrate 100 can be a horizontal surface or a curved surface; the bonding surface of the piezoelectric substrate 200 is arranged correspondingly to the bonding surface of the support substrate 100, so that the support substrate 100 and the piezoelectric substrate 200 are bonded with the corresponding bonding surfaces.

[0053] Specifically, the following is an example of two support layers, and the bonding surface of the support substrate 100 is a horizontal surface. The support layer 120 includes a first support layer 121 and a second support layer 122. The first support layer 121 is closest to the substrate 110, and the second support layer 122 is farthest from the substrate 110. The first support layer 121 is covered on the substrate 110, that is, the first support layer 121 is located between the substrate 110 and the piezoelectric substrate 200. The second support layer 122 is covered on the first support layer 121, that is, the second support layer 122 is located between the first support layer 121 and the piezoelectric substrate 200. The piezoelectric substrate 200 is bonded with the second support layer 122, wherein the piezoelectric substrate 200 includes a piezoelectric layer 220 and a damage layer 210; that is, the piezoelectric layer 220 is bonded with the second support layer 122, and the damage layer 210 covers the piezoelectric layer 220. The thickness of the first support layer 121 is greater than the thickness of the damage layer 210, and the thickness of the second support layer 122 is greater than the thickness of the damage layer 210.

[0054] S20, bonding the piezoelectric substrate on the support substrate.

[0055] The piezoelectric substrate 200 can be a piezoelectric single crystal or a piezoelectric polycrystal, and can be at least one of the following materials: barium titanate BT, lead zirconate titanate PZT, modified lead zirconate titanate, lead metaniobate, lead barium lithium niobate PBLN, modified lead titanate PT, quartz (quartz crystal), lithium gallate, lithium germanate, titanium germanate, and iron transistor lithium niobate, lithium tantalate, lithium niobate, etc. In a preferred embodiment, the thinner the piezoelectric substrate 200, the higher the Q value. For example, the piezoelectric substrate can be a lithium tantalate substrate with a 15°-52° Y-axis cut and an X-axis propagation.

[0056] Specifically, the bonding surface of the piezoelectric substrate 200 is bonded to the bonding surface of the support substrate 100, i.e., the piezoelectric substrate 200 is bonded to the second support layer 122 of the support substrate, so that the piezoelectric substrate 200 and the support substrate 100 form an integral whole.

[0057] In some embodiments, if the topography of the support substrate 100 is not planar, the thickness of the bonded piezoelectric substrate 200 will also change, i.e., the thickness of the piezoelectric substrate 200 is not uniform, and the piezoelectric substrate 200 can have a larger thickness in some areas. Therefore, in order to reduce the difficulty of ion beam etching, the piezoelectric substrate 200 can be thinned and polished first. For example, if the total thickness of the bonded piezoelectric substrate 200 and the support substrate 100 exceeds a threshold thickness, the piezoelectric substrate 200 is thinned and polished so that the total thickness of the piezoelectric substrate 200 and the support substrate 100 is less than or equal to the threshold thickness.

[0058] The threshold thickness can be set according to design requirements, which is not set here.

[0059] The thinning and polishing can first use a grinding machine to grind the side of the piezoelectric substrate 200 in the composite substrate 10 away from the support substrate 100, and then use a grinding machine for further grinding. The thinning and polishing can be further performed by chemical mechanical grinding, for example, using a CMP grinder (Chemical Mechanical Polishing) to grind the thickness of the piezoelectric substrate 200 to a mirror surface.

[0060] S30, etching the piezoelectric substrate using an ion beam to form a composite substrate; wherein the surface of the piezoelectric substrate away from the support substrate forms a damage layer, and the thickness of the damage layer is less than 0.00075λ.

[0061] In some embodiments, the difference between the maximum and minimum thickness of the etched piezoelectric substrate is less than 40 nm.

[0062] In order to etch the piezoelectric substrate 200, the piezoelectric substrate 200 can be etched by an ion beam etching method to trim the piezoelectric substrate 200.

[0063] Specifically, after the support substrate 100 and the piezoelectric substrate 200 are bonded and thinned and polished, the side of the piezoelectric substrate 200 away from the support substrate 100 is etched by an ion beam to form a corresponding composite substrate, and the difference between the maximum and minimum thicknesses of the piezoelectric substrate 200 after etching is less than 40 nm.

[0064] In some embodiments, before etching by the ion beam, the etching process parameters of the ion beam, such as the emission current and the emission voltage, are determined so that the thickness of the piezoelectric substrate 200 after etching meets the corresponding device requirements.

[0065] The etching process parameters can be determined according to the thickness requirements of the piezoelectric substrate 200, i.e., the piezoelectric substrate has a corresponding initial thickness at each point after bonding, and a target thickness is required after etching, i.e., the thickness requirement of the piezoelectric substrate 200, so a certain thickness of the piezoelectric substrate 200 needs to be etched off, which is defined as the sacrifice thickness here; then the ion beam needs to etch off the sacrifice thickness, and the corresponding etching process parameters are set.

[0066] In addition, etching the piezoelectric substrate 200 by the ion beam forms a damage layer 300 on the etched surface of the piezoelectric substrate 200, and a relatively large thickness of the damage layer 300 will cause a more serious insertion loss, e.g., when the thickness of the damage layer 300 is greater than 3 nm, and when the thickness of the damage layer is 3-10 nm, the insertion loss is 1.47 dB, and the electromechanical coupling coefficient of the corresponding filter is 7.8%. In addition, when the distance between adjacent two interdigital electrodes is less than 3 μm, the influence of the damage layer 210 on the insertion loss increases significantly, therefore, for the case where the distance between adjacent two interdigital electrodes is less than 3 μm, especially when the distance between adjacent two interdigital electrodes is less than 1 μm, on the one hand, the piezoelectric substrate 200 is etched by the ion beam etching method to improve the thickness uniformity of the piezoelectric substrate 200; and on the other hand, the surface of the piezoelectric substrate is polished after ion etching to make the thickness of the damage layer 210 of the piezoelectric substrate 200 lower than the sensitive thickness of the filter to the damage layer 210, thereby ensuring the characteristics of the filter.

[0067] Therefore, in order to reduce the thickness of the damage layer 300, the current range of the emission current is set to 10-15 mA, for example, the emission current is 12 mA, 13 mA or 14 mA; and the voltage range of the emission voltage is set to 800-1200 V, for example, the emission voltage is 900 V, 1000 V or 1100 V; and then the corresponding ion beam is emitted at the set emission current and emission voltage, and the etched surface of the piezoelectric substrate is etched by the ion beam. The thickness of the damage layer 300 generated after etching is less than 3 nm, for example, 2 nm, 1 nm, 0.8 nm or 0.7 nm, and when the thickness of the damage layer is less than 1 nm, the insertion loss of the corresponding filter is 1.113 dB, and the electromechanical coupling coefficient is 8.31%.

[0068] In addition, since the piezoelectric substrate 200 is etched by the ion beam, the surface roughness of the etched piezoelectric substrate 200 is reduced, for example, the surface roughness of the piezoelectric substrate 200 measured in the present application is 0.178 nm; the surface roughness is the smoothness of the piezoelectric substrate 200, and the smoother the surface of the piezoelectric substrate 200, the better the electrical performance of the corresponding device.

[0069] In some embodiments, the thickness of the support substrate 100 can also be used as a reference, and the initial thickness of the whole after bonding the piezoelectric substrate 200 can be obtained, and then the thickness of the support substrate 100, the initial thickness and the target thickness to be reached are used to determine the sacrificial thickness that needs to be etched off.

[0070] In some embodiments, the thickness distribution data of the piezoelectric substrate 200 can be obtained by measuring the thickness of the polished piezoelectric substrate using a laser interference optical film thickness meter.

[0071] For example, a coordinate system is established, and the thickness of the support substrate 100, the initial thickness of the whole after bonding the piezoelectric substrate 200 and the target thickness to be reached are obtained on each abscissa to determine the sacrificial thickness that needs to be etched off on each abscissa. In addition, the coordinate distance can also be based on the diameter of the ion beam spot; the thickness measurement can be measured by an optical film thickness meter.

[0072] Referring to Figure 5 , Figure 5 is a filter characteristic comparison chart.

[0073] Figure 5The filter characteristic represented by the long dashed line is obtained by testing on the basis that the support substrate is a horizontal panel. The short dashed line is a filter characteristic without ion beam etching, in which the insertion loss is 1.148 dB; the solid line is a filter characteristic with ion beam etching in a general case, in which the insertion loss is 1.47 dB; and the long dashed line is a filter characteristic with the optimized ion beam etching of the present application, in which the insertion loss is 1.113 dB.

[0074] It can be seen that the etching of the piezoelectric substrate 200 by the ion beam can effectively control the thickness uniformity of the piezoelectric substrate, that is, the difference between the maximum and minimum values of the thickness of the piezoelectric substrate will be less than 60 nm, but the thickness of the damage layer 300 generated by the etching will be larger, 3-10 nm, which will cause a larger insertion loss and affect the performance of the filter; and the etching of the piezoelectric substrate 200 by the optimized ion beam of the present application can effectively control the thickness uniformity of the piezoelectric substrate while generating a smaller thickness of the damage layer 300, less than 3 nm, specifically, the thickness of the damage layer 300 is less than 1 nm, so that the insertion loss of the corresponding filter is smaller, and the frequency of the filter is high and concentrated.

[0075] S40, a plurality of interdigital electrodes are formed on the piezoelectric substrate, and the spacing between adjacent two interdigital electrodes is less than 3 pm.

[0076] The structure parameters of the interdigital electrode include four parameters: the number of interdigital electrode pairs, the interdigital width, the spacing between adjacent interdigital electrodes, and the thickness of the interdigital electrode, that is, the four structure parameters of the interdigital electrode affect the electrical performance of the subsequent product.

[0077] Specifically, the number of interdigital electrode pairs, the interdigital width, and the thickness of the interdigital electrode can be set according to actual needs, which are not limited here; the spacing between the interdigital electrodes is set to be less than 3 pm, so as to cooperate with the aforementioned setting that the thickness of the loss layer in the piezoelectric substrate is set to be less than 0.00075l, and the thickness uniformity of the piezoelectric substrate 200 is ensured, so as to achieve the required frequency high concentration of the filter formed based on the composite substrate.

[0078] In some embodiments, the spacing between adjacent two interdigital electrodes can also be set to be less than 1 pm, so as to cooperate with the aforementioned setting that the thickness of the loss layer in the piezoelectric substrate is set to be less than 0.00075l, and the thickness uniformity of the piezoelectric substrate 200 is better ensured, so as to achieve the required frequency high concentration of the filter formed based on the composite substrate.

[0079] In this embodiment, the corresponding ion beam is emitted by the optimized emission parameters, thereby etching the piezoelectric substrate 200, making the surface of the piezoelectric substrate 200 smooth and the thickness of the piezoelectric substrate 200 highly uniform, improving the frequency concentration of the filter; and greatly reducing the thickness of the damage layer caused by the ion beam, reducing insertion loss, and even avoiding the generation of abnormal insertion loss, effectively ensuring the electrical properties of the filter.

[0080] In addition, this application also includes a filter, as detailed below.

[0081] See Figure 6 , Figure 6 This is a schematic diagram of the structure of the first embodiment of the filter in this application.

[0082] like Figure 6 As shown, the filter 1 includes the aforementioned elastic wave device 10, wherein the elastic wave device 10 can be manufactured by the aforementioned elastic wave device manufacturing method, or the elastic wave device 10 can be the aforementioned elastic wave device 10, that is, the elastic wave device 10 includes a bonded support substrate 100 and a piezoelectric substrate 200; a plurality of interdigitated electrodes 300 are spaced apart on the side of the composite substrate away from the support substrate 100, that is, the interdigitated electrodes 300 are spaced apart on the side of the piezoelectric substrate 200 away from the support substrate 100.

[0083] The wavelength of the elastic wave in the elastic wave device is λ, and the distance between adjacent interdigitated electrodes in the elastic wave device is the IDT spacing (Interdigitated Transducer), which can be set according to the product type.

[0084] Specifically, taking a planar substrate as an example, the filter 1 includes an elastic wave device 10, which includes a support substrate 100, a piezoelectric substrate 200, and interdigitated electrodes 300. The support substrate 100 and the piezoelectric substrate 200 are bonded together, and the bonded piezoelectric substrate 200 is etched by an ion beam to form a composite substrate. The thickness of the etched piezoelectric substrate 200 is less than 3 μm, and the difference between the maximum and minimum thickness of the piezoelectric substrate 200 is less than 40 nm. A damage layer 210 is also formed on the etched surface of the piezoelectric substrate 200. The thickness of the damage layer 210 is less than 3 nm, such as 1 nm. Since a damage layer of less than or equal to 1 nm does not reach the sensitive thickness of the damage layer corresponding to the filter, it will not affect the characteristics of the filter. Interdigitated electrodes 300 are then formed on the damage layer 210 at intervals to form the filter.

[0085] In some embodiments, the spacing between two adjacent interdigital electrodes 20 is less than 3 μm, such as 2 μm, 1 μm, 0.8 μm, 0.5 μm, 0.4 μm, 0.2 μm, etc.

[0086] In this embodiment, the composite substrate formed above is used as a base to form a corresponding filter, which can effectively improve the frequency concentration of the filter, reduce insertion loss, and even prevent abnormal insertion loss, thus ensuring the electrical properties of the filter.

[0087] See Figure 7 , Figure 7 This is a schematic diagram of the structure of the second embodiment of the filter in this application.

[0088] like Figure 7 As shown, the filter 1 includes a composite substrate 10 and a plurality of interdigitated electrodes 20. The composite substrate 10 includes a bonded support substrate 100 and a piezoelectric substrate 200. The support substrate 100 includes a substrate 110 and at least one support layer 120. For example, the at least one support layer includes a first support layer 121 and a second support layer 122. A damage layer 210 is formed on the surface of the piezoelectric substrate 200 etched by the ion beam. The thickness of the damage layer 210 is less than 3 nm, such as 1 nm. The difference between the maximum and minimum thickness of the piezoelectric substrate 200 is less than 40 nm.

[0089] This disclosure also provides a module including at least one of the aforementioned elastic wave devices. According to one example, the module includes a wiring substrate, an integrated circuit element (IC), an elastic wave device, an inductor, and a sealing portion. According to one example, the IC is mounted inside the wiring substrate. The IC includes switching circuitry and a low-noise amplifier. At least one elastic wave device is mounted on the main surface of the wiring substrate. The inductor is mounted on the main surface of the wiring substrate. The inductor is mounted for impedance matching. For example, the inductor is an integrated passive device (IPD). The sealing portion seals multiple electronic components, including the elastic wave device.

[0090] In the several embodiments provided in this application, it should be understood that the disclosed systems and devices can be implemented in other ways. For example, the system implementations described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0091] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An elastic wave device, characterized in that, include: Support substrate; A piezoelectric substrate bonded to a support substrate, wherein the surface of the piezoelectric substrate away from the support substrate has a damage layer, the thickness of which is less than 0.00075λ; Multiple interdigitated electrodes are spaced apart on the side of the piezoelectric substrate away from the supporting substrate, and the distance between two adjacent interdigitated electrodes is less than 3 μm; Wherein, λ is the wavelength of the elastic wave of the elastic wave device, which is determined according to the electrode period of the interdigitated electrode.

2. The elastic wave device according to claim 1, characterized in that, The supporting substrate includes: Substrate; At least one support layer is disposed between the substrate and the piezoelectric substrate, and the support layer farthest from the substrate is bonded to the piezoelectric substrate, wherein the thickness of the support layer farthest from the substrate is greater than the thickness of the damaged layer.

3. The elastic wave device according to claim 2, characterized in that, The support layer includes: A first support layer is located between the substrate and the piezoelectric substrate; A second support layer is located between the first support layer and the piezoelectric substrate, wherein the thicknesses of the first support layer and the second support layer are respectively greater than the thickness of the damaged layer.

4. The elastic wave device according to claim 3, characterized in that, The thickness of the first support layer is less than 2λ.

5. The elastic wave device according to claim 3, characterized in that, The thickness of the second support layer is less than 0.004λ.

6. The elastic wave device according to claim 1, characterized in that, The thickness of the damaged layer is less than 3 nm.

7. The elastic wave device according to claim 6, characterized in that, The thickness of the damaged layer is less than or equal to 1 nm.

8. The elastic wave device according to claim 1, characterized in that, The difference between the maximum and minimum thickness of the piezoelectric substrate is less than 40 nm.

9. The elastic wave device according to claim 1, characterized in that, The spacing between two adjacent interdigitated electrodes is less than 1 μm.

10. The elastic wave device according to claim 1, characterized in that, The insertion loss of the elastic wave device is less than 1.4 dB.

11. A method for manufacturing an elastic wave device, comprising the steps of: Provide a support substrate; A piezoelectric substrate is bonded onto the support substrate; A composite substrate is formed by etching the piezoelectric substrate using an ion beam, wherein... A damage layer is formed on the surface of the piezoelectric substrate away from the supporting substrate, and the thickness of the damage layer is less than 0.00075λ. A plurality of interdigitated electrodes are formed on the piezoelectric substrate at intervals, with the spacing between two adjacent interdigitated electrodes being less than 3 μm.

12. The method according to claim 11, characterized in that, The etching process parameters of the ion beam are determined based on the thickness requirements of the piezoelectric substrate. The etching process parameters include emission current and emission voltage. The emission current ranges from 10mA to 15mA, and the emission voltage ranges from 800V to 1200V. The composite substrate is formed by etching the piezoelectric substrate using the ion beam based on the etching process parameters.

13. The method according to claim 12, characterized in that: The piezoelectric substrate is etched using the etching process parameters to make the thickness of the damaged layer less than 1 nm.

14. An electronic module comprising the elastic wave device according to any one of claims 1-10.

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