Support substrate and preparation method thereof, composite substrate, electronic device and module

Abstract

The embodiment of the present invention provides a support substrate and a preparation method thereof, a composite substrate, an electronic device and a module. The support substrate is formed of a polycrystalline material, has a main support surface for supporting a piezoelectric layer and a back surface opposite to the main support surface, the surface roughness Sz of the back surface is greater than or equal to 3 microns, and the surface roughness Sa of the back surface is greater than or equal to 0.2 microns. The support substrate provided by the embodiment of the present invention can achieve a suitable warpage, reduce the adverse effects on subsequent processes, and reduce the adverse effects on other performance parameters of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic device processing and manufacturing, and in particular to a supporting substrate and a preparation method thereof, a composite substrate, an electronic device and a module. Background Art

[0002] In some elastic wave devices, such as SAW (surface acoustic wave) devices, more specifically TC-SAW (temperature compensated filter), a composite substrate obtained by bonding a piezoelectric layer and a supporting substrate is required. The warpage of the supporting substrate used for bonding is an important parameter. When the warpage is too large, the subsequent chip preparation process and packaging process can only be manually loaded and unloaded, and the equipment cannot be automatically operated. However, in the production process, it is not only necessary to ensure that the supporting substrate has a suitable warpage, but also to prevent the deterioration of other parameters or performance caused by simply achieving a suitable warpage, and to prevent adverse effects on the efficiency, cost, product yield, etc. of other processes. For this reason, there is no suitable solution in the prior art to reduce the warpage of the supporting substrate. Summary of the invention

[0003] The purpose of the present invention is to reduce the warping of a supporting substrate to reduce the difficulty of production. A supporting substrate and a preparation method thereof, a composite substrate, an electronic device and a module are provided, which can achieve a suitable warping, reduce the adverse effects on subsequent processes, and reduce the adverse effects on other performance parameters of the product.

[0004] One embodiment of the present invention provides a supporting substrate, which has a main supporting surface for combining with a piezoelectric layer and a back surface opposite to the main supporting surface, the surface roughness Sz of the back surface is greater than or equal to 3 microns, and the surface roughness Sa of the back surface is greater than or equal to 0.2 microns.

[0005] One embodiment of the present invention provides a supporting substrate, which is formed of a polycrystalline material and has a main supporting surface for supporting a piezoelectric layer and a back surface opposite to the main supporting surface, wherein the surface roughness Sz of the back surface is greater than or equal to the average grain size of the supporting substrate.

[0006] An embodiment of the present invention provides a preparation method for the aforementioned supporting substrate, comprising making a crystal ingot from raw material crystal powder, and processing the crystal ingot into a pre-processed substrate; polishing two opposite surfaces of the pre-processed substrate respectively; and sandblasting one of the two polished surfaces of the pre-processed substrate to obtain the supporting substrate.

[0007] An embodiment of the present invention provides a composite substrate, comprising a piezoelectric layer, and the aforementioned supporting substrate or a supporting substrate obtained by the aforementioned preparation method; the piezoelectric layer is arranged on the main supporting surface of the supporting substrate.

[0008] One embodiment of the present invention provides an electronic device including the aforementioned composite substrate.

[0009] One embodiment of the present invention provides a module including a wiring substrate, a plurality of external connection terminals, an integrated circuit component, an inductor, and a sealing portion, and the electronic device described in any one of the above.

[0010] The above-mentioned embodiments of the present invention have at least one or more of the following beneficial effects: the supporting substrate can have the effect of reducing the warpage by having a specific surface roughness Sz on the back side. Combined with the specific surface roughness Sa on the back side, a lower light transmittance can be achieved, which can avoid the problem of difficult alignment in subsequent processes, and can also effectively reflect and scatter body waves and suppress noise. The preparation method of the supporting substrate can achieve a smaller warpage and a smaller TTV (Total Thickness Variation) while reducing the light transmittance of the prepared supporting substrate by first polishing the two relative surfaces of the pre-treated substrate and then sandblasting the surface of the pre-treated substrate used to form the back side of the supporting substrate to achieve roughening, thereby avoiding the problem of difficult alignment in subsequent processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The specific implementation modes of the present invention will be described in detail below with reference to the accompanying drawings.

[0012] Figure 1 A schematic structural diagram of a support substrate provided in one embodiment of the present invention.

[0013] Figure 2 A schematic diagram of the light transmittance of a supporting substrate in various wavelength bands provided by an embodiment of the present invention.

[0014] Figure 3 A schematic structural diagram of a composite substrate provided in one embodiment of the present invention.

[0015] Figure 4 A schematic structural diagram of an electronic device provided in one embodiment of the present invention.

[0016] Figure 5 A schematic structural diagram of another electronic device provided by an embodiment of the present invention.

[0017] Figure 6 A schematic structural diagram of another electronic device provided by an embodiment of the present invention.

[0018] Figure 7A schematic structural diagram of yet another electronic device provided in an embodiment of the present invention.

[0019] Figure 8 A schematic diagram of the structure of a module provided for one embodiment of the present invention.

[0020] [Description of Reference Numerals]

[0021] 1000, module; 100, electronic device; 10, composite substrate; 11, supporting substrate; 111, main supporting surface; 112, back surface; 12, piezoelectric layer; 121, main surface; 13, intermediate layer; 20, electrode; 21, IDT electrode; 22, electrode pad; 30, packaging substrate; 41, first sealing structure; 42, second sealing structure; 51, bump; 52, first conductive portion; 53, first external terminal electrode; 54, second conductive portion; 55, second external terminal electrode; 60, gap; 70, cover; 400, inductor; 500, sealing portion; 600, integrated circuit component; 700, wiring substrate; 701, external connection terminal. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] It should also be noted that the division of multiple embodiments in the present invention is only for the convenience of description and should not constitute a special limitation. The features in various embodiments can be combined and referenced to each other without contradiction.

[0026] The embodiment of the present invention further provides a method for preparing a support substrate, which can prepare a support substrate 11, wherein the support substrate 11 has a main support surface 111 for supporting a piezoelectric layer and a back surface 112 opposite to the main support surface 111. The method for preparing the support substrate includes:

[0027] Step S1: using raw material crystal powder to make a crystal ingot, and processing the crystal ingot into a pre-processed substrate;

[0028] Step S2: polishing two opposite surfaces of the pre-treated substrate respectively;

[0029] Step S3: performing sandblasting on one of the two polished surfaces of the pre-processed substrate to obtain a supporting substrate.

[0030] The raw material crystal powder in step S1 is, for example, a powder of a polycrystalline material, and the polycrystalline material is, for example, any one of polycrystalline magnesium aluminum spinel, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and polycrystalline quartz. In step S1, the raw material crystal powder can be made into an ingot by processes such as CIP (Cold Isostatic Pressing) and HIP (Hot Isostatic Pressing), and a pre-processed substrate can be obtained by cutting and grinding.

[0031] For example, the two relatively polished surfaces of the pre-treated substrate in step S2 are respectively referred to as the first surface and the second surface. The first surface is used as the main support surface 111 for supporting the piezoelectric layer in the subsequent process. In step S2, for example, the first surface is specifically polished to a surface roughness Sa less than or equal to 0.6 nm, so that it can be firmly bonded to the piezoelectric layer later. According to ISO 25178, the roughness can be represented by parameters such as the arithmetic mean height Sa, the maximum height Sz, the root mean square height Sq, and the maximum peak height Sp. The surface roughness Sa in this application is the arithmetic mean height Sa in ISO 25178.

[0032] In the related art, the initial substrate needs to be polished to obtain the supporting substrate, and usually the side that needs to be bonded with the piezoelectric layer (corresponding to the first side of the pre-treated substrate in this application) is polished to achieve the roughness required for bonding. However, the inventors found in the production process that the substrate obtained in this way has a large warpage, and the equipment cannot be automatically operated in the subsequent process, which is difficult to produce. In addition, the TTV of the surface of the substrate obtained in this way can only be about 2 microns, and cannot reach a smaller TTV of 1 micron. In this embodiment, after the step S2 process, the warpage of the pre-treated substrate can reach less than 200 microns, which can reduce the difficulty of production and the TTV of its surface can reach less than or equal to 1 micron, so as to better reduce the impact on the uniformity of the film thickness of the piezoelectric layer in the subsequent process.

[0033] As mentioned above, in step S3, the second surface of the pre-treated substrate is sandblasted, and the second surface after the sandblasting becomes the back surface 112 of the support substrate 11. The grains of the second surface of the pre-treated substrate are broken through by sandblasting to achieve the roughening of the second surface, so that the surface roughness Sz of the back surface 112 of the support substrate 11 can meet the target requirements. Thus, a lower warpage is achieved. The surface roughness Sz in this application is the maximum height Sz in ISO 25178.

[0034] In the related art, the chip needs to be aligned during the packaging process of the elastic wave device. An infrared sensor can be used. The infrared sensor is a photoelectric sensor. It first converts the measured change into a change in the light signal, and then further converts the light signal into an electrical signal with the help of a photoelectric element. However, when the transmittance of the object to be measured is high and the reflectivity is low, the light signal cannot be received during the detection and the shape and position of the object to be measured cannot be determined. Therefore, when the transmittance of the supporting substrate 11 is high, the light emitted by the alignment device will pass through the supporting substrate 11, resulting in alignment failure.

[0035] In an embodiment of the present invention, by first polishing the two relative surfaces of the pre-treated substrate and then sandblasting the surface of the pre-treated substrate used to form the back side 112 of the supporting substrate 11 to achieve roughening, a smaller warpage and TTV can be achieved through double-sided polishing while reducing the transmittance of the manufactured supporting substrate 11, thereby achieving a smaller warpage and TTV while avoiding the problem of difficult alignment in subsequent processes.

[0036] In step S3 , the surface roughness of the surface after the sandblasting treatment is also measured. When the surface roughness reaches the target range, step S3 can be stopped to obtain the support substrate 11 .

[0037] In some embodiments, the target range of the surface roughness of the surface after sandblasting is Sz greater than or equal to 3 microns, and Sa greater than 0.2 microns. The support substrate 11 obtained in this way can reduce the warpage because the back surface 112 has a specific surface roughness Sz, and can effectively reflect and scatter body waves and suppress noise because the back surface has a specific surface roughness Sa, and can also reduce the difficulty of alignment.

[0038] In other embodiments, the target range of the surface roughness of the surface after sandblasting is that the surface roughness Sz is greater than or equal to the average grain size of the pre-treated substrate. The pre-support substrate includes, for example, a plurality of grains. For example, the grain size of the pre-support substrate can be, for example, 1 to 100 microns, that is, the pre-support substrate can have grains of different sizes, for example, grains of different sizes such as 10 microns, 25 microns, 40 microns, 50 microns, 60 microns, and 100 microns, and the grain size of the smallest grain is not less than 1 micron (≥1μm), and the grain size of the largest grain is not more than 100 microns (≤100μm). The average grain size of these grains of different sizes is the average grain size of the pre-support substrate. The calculation of the average grain size can be, for example, dividing the pre-support substrate into multiple regions, and counting the number of grains of each particle size in the multiple regions respectively, and averaging the number of corresponding particle sizes as weights, that is, the average grain size of the pre-support substrate is the weighted average of the particle sizes of all grains in the pre-support substrate.

[0039] In some embodiments, the pressure of the sandblasting in step S3 is, for example, 0.2-0.6 MPa. The particle size of the sand particles in the sandblasting is 1200-1800 mesh. The sand particles in the sandblasting can be selected from any one or more of high-hardness sand particles such as silicon carbide, aluminum oxide, and boron carbide.

[0040] In some embodiments, the thickness of the pre-treated substrate obtained in step S1 is greater than or equal to twice the maximum grain size thereof. The thickness of the pre-treated substrate is the distance between the first surface and the second surface. For example, if the grain size of the grains in the pre-treated substrate is 5 to 60 microns, that is, the grain size of the smallest grain in the pre-treated substrate is not less than 5 microns (≥5μm), and the grain size of the largest grain is not more than 60 microns (≤60μm), then the maximum grain size in the pre-treated substrate is 60 microns, and the thickness of the pre-treated substrate should be greater than or equal to 120 microns, so as to facilitate the sandblasting in step S3.

[0041] In some embodiments, for example, after step S3, the transmittance of the prepared supporting substrate 11 is also tested. When it is detected that the transmittance of the supporting substrate 11 satisfies that the transmittance in the wavelength band of 240~780nm is less than 9%, and the transmittance in the wavelength band below 550nm is less than 0.1%, it indicates that the supporting substrate 11 is more conducive to subsequent accurate alignment.

[0042] Based on the preparation method of the supporting substrate provided in the above embodiment, Figure 1 As shown, an embodiment of the present invention provides a support substrate 11, which is, for example, made by the above-mentioned support substrate preparation method. The support substrate 11 is formed of a polycrystalline material and has a main support surface 111 for supporting a piezoelectric layer and a back surface 112 opposite to the main support surface 111. In the support substrate 11, the back surface 112 has a specific surface roughness Sz.

[0043] For example, in the support substrate 11, the surface roughness Sz of the back surface 112 is greater than or equal to 3 microns, and the surface roughness Sa of the back surface 112 is greater than or equal to 0.2 microns. Or in the support substrate 11, the surface roughness Sz of the back surface 112 is greater than or equal to the average grain size of the support substrate.

[0044] For example, the material of the support substrate 11 may be a polycrystalline material, such as any one of polycrystalline magnesium aluminum spinel, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and polycrystalline quartz.

[0045] The support substrate 11 includes a plurality of crystal grains. For example, the crystal grain size in the support substrate 11 may be, for example, 1 to 100 microns, that is, the support substrate 11 may have crystal grains of different sizes, for example, the support substrate 11 may have crystal grains of different sizes such as 10 microns, 25 microns, 40 microns, 50 microns, 60 microns, and 100 microns, and the crystal grain size of the smallest crystal grain is not less than 1 micron (≥1 μm), and the crystal grain size of the largest crystal grain is not more than 100 microns (≤100 μm). The average crystal grain size of these crystal grains of different sizes is the average crystal grain size of the support substrate 11. For example, if the average crystal grain size in the support substrate 11 is 3 microns, the surface roughness Sz of the back surface 112 is greater than or equal to 3 microns. For example, if the average crystal grain size in the support substrate 11 is 6 microns, the surface roughness Sz of the back surface 112 is greater than or equal to 6 microns.

[0046] Refer to Table 1, which shows the data of the average grain size of some supporting substrates 11, the surface roughness Sz of the back side 112 and the warpage of the supporting substrate 11 provided in the embodiments of the present application.

[0047] Table 1:

[0048]

[0049] It can be seen from Table 1 that when the surface roughness Sz is 2.3 microns, the surface roughness Sz is less than the average grain size, and the warpage exceeds 200. When the surface roughness is above 3.4 microns, the surface roughness Sz is greater than the average grain size, and the warpage is within 200 microns. Therefore, this embodiment is conducive to achieving the effect of reducing the warpage by setting the surface roughness Sz to be greater than the average grain size.

[0050] Refer to Table 2, which shows the relationship between the average grain size of some supporting substrates 11 provided in the embodiments of the present application, the surface roughness Sa of the back surface 112 and the transmittance (for light with a wavelength of less than 780 nm).

[0051] Table 2:

[0052]

[0053] According to Table 2, when the surface roughness Sz of the back surface 112 is less than 3 microns and the surface roughness Sa reaches 0.2 microns, the transmittance is 16.30%, which is relatively large. When the surface roughness Sz of the back surface 112 reaches more than 3.4 microns and the surface roughness Sa reaches more than 0.4 microns, the transmittance can reach less than 8.90%, and as the surface roughness Sz and the surface roughness Sa gradually increase, the reflectivity is gradually lower, which can reduce the difficulty of alignment in subsequent processes.

[0054] The supporting substrate 11 provided in the embodiment of the present invention has a special surface roughness Sz, so that the warpage of the supporting substrate 11 can be less than 200 microns. Combined with the special surface roughness Sa, it can have a lower light transmittance. On the one hand, under the condition of the specific surface roughness Sa, the supporting substrate 11 can effectively reflect and scatter body waves and suppress noise. On the other hand, it can avoid the problem of difficult alignment in subsequent processes.

[0055] In one embodiment of the present invention, referring to Figure 2 The light transmittance of the support substrate 11 provided in the embodiment of the present invention is less than 9% in the wavelength range of 240-780nm. More specifically, the light transmittance is less than 0.1% in the wavelength range below 550nm, or even close to 0, which can further reduce the difficulty of alignment and ensure the efficient performance of subsequent processes.

[0056] In some embodiments, the thickness of the support substrate 11 is greater than or equal to twice the maximum grain size of the support substrate 11. For example, if the grain size of the grains in the support substrate 11 is 5 to 60 microns, that is, the grain size of the smallest grain in the support substrate 11 is not less than 5 microns (≥5μm), and the grain size of the largest grain is not more than 60 microns (≤60μm), then the maximum grain size of the support substrate 11 is 60 microns, and the thickness of the support substrate 11 should be greater than or equal to 120 microns. The thickness of the support substrate 11 is the distance between the main support surface 111 and the back surface 112.

[0057] In some embodiments, the surface roughness Sa of the main support surface 111 of the support substrate 11 is less than or equal to 0.6 nm (nanometer), wherein the surface roughness Sa is the arithmetic mean height Sa in ISO 25178.

[0058] In some embodiments, the warpage of the support substrate 11 is less than or equal to 200 micrometers.

[0059] The embodiment of the present invention further provides a composite substrate 10, referring to Figure 3 The composite substrate 10 includes a piezoelectric layer 12, and the supporting substrate 11 described in the above embodiment or the supporting substrate 11 prepared by the preparation method of the above embodiment. The piezoelectric layer 12 is arranged on the main supporting surface 111 of the supporting substrate 11. Specifically, the piezoelectric layer 12 can be bonded to the main supporting surface 111 of the supporting substrate 11. The two can be directly bonded by van der Waals force. The piezoelectric layer 12 can be, for example, lithium tantalate or lithium niobate material.

[0060] The composite substrate 10 can be obtained by separately preparing the aforementioned supporting substrate 11 and piezoelectric layer 12 and then bonding the supporting substrate 11 and the piezoelectric layer 12, or can be obtained by the preparation method of the composite substrate 10 provided in an embodiment of the present invention.

[0061] The method for preparing the composite substrate provided by the embodiment of the present invention includes:

[0062] Step S1: using raw material crystal powder to make a crystal ingot, and processing the crystal ingot into a pre-processed substrate;

[0063] Step S2: polishing two opposite surfaces of the pre-treated substrate respectively;

[0064] Step S4: bonding the polished pre-treated substrate to the piezoelectric substrate;

[0065] Step S5: performing sandblasting on the surface of the polished pre-processed substrate facing away from the piezoelectric substrate to obtain the composite substrate.

[0066] Among them, the specific steps of step S1 and step S2 can refer to the specific description of step S1 and step S2 in the preparation method of the aforementioned support substrate. The piezoelectric substrate in step S4 of step S5 is, for example, a finished piezoelectric substrate obtained by cutting, grinding, polishing and reducing a lithium tantalate ingot made of a lithium tantalate material. Before step S5, for example, step S6 is also included, in which the piezoelectric substrate is thinned and polished to obtain a piezoelectric layer 12 of a target film thickness. The thickness of the piezoelectric layer 12 is, for example, 3 microns. According to the above description of step S2, since the TTV of the surface of the substrate pretreated by step S2 can be less than or equal to 1 micron, the thickness of the piezoelectric layer 12 obtained in step S6 can be controlled to 3±0.3μm, that is, the thickness of the piezoelectric layer 12 can be 2.7~3.3 microns. Step S5 can refer to the description in step S3, except that step S5 is performed after the polished pretreated substrate is combined with the piezoelectric substrate, while step S3 is performed after the polished pretreated substrate is combined with the piezoelectric substrate. After the sandblasting process in step S5 , the pre-treated substrate becomes the supporting substrate 11 , and the sandblasted surface thereof becomes the back surface 112 .

[0067] The preparation method of the composite substrate provided in the embodiment of the present invention can achieve a smaller warpage and TTV through double-sided polishing in step S2, and at the same time reduce the transmittance of the prepared composite substrate through step S5, thereby achieving a smaller warpage and TTV while avoiding the problem of difficult alignment in subsequent processes. In addition, in the preparation method of the composite substrate provided in this embodiment, there is no need to thin the back of the pre-treated substrate or the formed support substrate 11 after step S5, because S5 has roughened the back of the support substrate to achieve the ideal transmittance and surface roughness. And this processing method can reduce the warpage of the support substrate 11, so that the warpage of the support substrate in the composite substrate 10 is less than or equal to 200 microns, making the processing window of the back-end packaging larger.

[0068] like Figure 4 As shown, an embodiment of the present invention further provides an electronic device 100, including the supporting substrate 11 in the aforementioned embodiment or the composite substrate 10 in the aforementioned embodiment. Or the supporting substrate 11 prepared by the aforementioned supporting substrate preparation method, or the composite substrate 10 obtained by the aforementioned composite substrate preparation method. In the composite substrate 10, the piezoelectric layer 12, for example, includes a main surface 121 facing away from the supporting substrate 11, and the electronic device 100, for example, also includes an electrode 20 arranged on the main surface 121, and the electrode 20, for example, includes an IDT electrode 21, IDT is an interdigital transducer, and the electronic device 100 is, for example, a SAW device. The electronic device 100 has the supporting substrate 11 in the aforementioned embodiment and has the same effect as the supporting substrate 11.

[0069] Reference Figure 5 In another embodiment of the present invention, the electronic device 100 (composite substrate 10) further includes an intermediate layer 13, which is located between the piezoelectric layer 12 and the supporting substrate 11. The acoustic velocity of the intermediate layer 13 is lower than that of the piezoelectric layer 12. That is, compared with the body wave propagating in the piezoelectric layer 12, the acoustic velocity of the body wave in the intermediate layer 13 is lower. In this embodiment, by providing the intermediate layer 13 with a low acoustic velocity, the acoustic velocity of the elastic wave can be reduced, and the energy of the elastic wave can be concentrated in the medium with a low acoustic velocity (i.e., the intermediate layer 13), which can reduce the loss and improve the Q value.

[0070] The material of the intermediate layer 13 is silicon oxide, silicon oxynitride, tantalum oxide, or any one of the materials with these materials as the main components. In some embodiments, the intermediate layer is made of silicon oxide, and the material of the piezoelectric layer 12 is lithium tantalate. The elastic constant of lithium tantalate has a negative temperature characteristic, while silicon dioxide has a positive temperature characteristic, thereby reducing the absolute value of the TCF (temperature drift coefficient) of the elastic wave device. Furthermore, the inherent acoustic impedance of silicon oxide is smaller than the inherent acoustic impedance of lithium tantalate, so the electromechanical coupling coefficient of the electronic component can be increased.

[0071] In some embodiments, the thickness of the intermediate layer 13 is greater than or equal to 0.5λ, where λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode 21. Specifically, the thickness of the intermediate layer 13 can be 0.6~0.8λ. In some embodiments, the thickness of the piezoelectric layer 12 is less than or equal to 2λ. Specifically, the thickness of the piezoelectric layer 12 can be less than 1λ. In a specific embodiment, λ is 2.25 microns, the piezoelectric layer 12 is 0.1λ~1λ, and the thickness of the intermediate layer 13 is 0.6λ.

[0072] The electronic device 100 provided in this embodiment may adopt CSP packaging (Chip Scale Package) or WLP packaging (Wafer Level Package).

[0073] For example, refer to Figure 6, which is a structural schematic diagram of an electronic device 100 using CSP packaging. The electronic device 100 includes a component (including a composite substrate 10 and an electrode 20), a packaging substrate 30, a first sealing structure 41 and a first external terminal electrode 53. The packaging substrate 30 is arranged opposite to the surface where the electrode 20 of the component is located (that is, the main surface 121 of the piezoelectric layer 12), and a gap 60 is formed between the packaging substrate 30 and the main surface 121. The first sealing structure 41 is arranged on the side of the packaging substrate 30 facing the component, covering the side of the component and the side facing away from the packaging substrate 30 to seal the gap 60 and seal the component. The electrode 20 includes an electrode pad 22 electrically connected to the IDT electrode 21, and the electrode pad 22 is electrically connected to the first conductive portion 52 in the wiring pattern on the packaging substrate 30 through the bump 51. The first conductive portion 52 is electrically connected to the first external terminal electrode 53 on the side of the packaging substrate 30 facing away from the component, so that the electronic device 100 can be electrically connected to an external device through the first external terminal electrode 53.

[0074] Among them, the materials of the packaging substrate 30 and the first sealing structure 41 can refer to the common substrate materials and sealing materials in the existing CSP packaging. The electrode pad 22, the bump 51, the first conductive part 52 and the first external terminal electrode 53 are all made of materials with good conductive properties. This embodiment is not limited to the above examples.

[0075] Reference Figure 7 , which is a structural schematic diagram of an electronic device 100 using CSP packaging. The electronic device 100 includes a component (including a composite substrate 10 and an electrode 20), a cover 70, a second sealing structure 42, and a second external terminal electrode. The cover 70 is arranged opposite to a side of the component on which the electrode 20 is arranged (that is, the main surface 121 of the piezoelectric layer 12), and a gap 60 is formed between the cover 70 and the main surface 121. The electrode 20 includes an electrode pad 22 electrically connected to the IDT electrode 21. The area on the main surface 121 where the IDT electrode 21 is arranged is called an effective area. The second sealing structure 42 is arranged between the cover 70 and the component and is arranged around the effective area. The second sealing structure 42 surrounds the electrode pad 22 to achieve sealing of the component. The second external terminal electrode 55 arranged on the surface of the cover 70 facing away from the component is connected to the electrode pad 22 through the second conductive portion 54 that penetrates the cover 70 and the second sealing structure 42, so that the electronic device 100 can be electrically connected to an external device through the second external terminal electrode 55.

[0076] The materials of the cover 70 and the second sealing structure 42 can refer to the cover material and sealing material used in the existing WLP package. The electrode pad 22, the second conductive part 54 and the second external terminal electrode 55 are all made of materials with good conductive properties, which is not limited in this embodiment.

[0077] Reference Figure 8The invention also provides a module 1000, including a wiring substrate 700, a plurality of external connection terminals 701, an integrated circuit component 600, an electronic device 100 (including a composite substrate 10), an inductor 400 and a sealing portion 500. A plurality of external connection terminals 701 are formed on one surface of the wiring substrate 700, and the plurality of external connection terminals 701 are mounted on a motherboard of a pre-set mobile communication terminal. The integrated circuit component 600 (which may be referred to as an IC) is mounted inside the wiring substrate 700. The integrated circuit component 600 includes a switching circuit and a noise amplifier. The electronic device 100 is mounted on the main surface of the wiring substrate 700. The inductor 400 is used for impedance matching, and for example, the inductor 400 is an integrated passive device (IPD: Integrated Passive Device). The sealing portion 500 is used to seal a plurality of electronic components including the electronic device 100 on the wiring substrate 700.

[0078] The module 1000 provided in this embodiment includes the electronic device 100 , that is, includes the supporting substrate 11 , and has the same effect as the supporting substrate 11 , which will not be described in detail herein.

[0079] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A supporting substrate, characterized in that: The supporting substrate is formed of a polycrystalline material, having a main supporting surface for supporting the piezoelectric layer and a back surface opposite to the main supporting surface, the surface roughness Sz of the back surface is greater than or equal to 3 microns, and the surface roughness Sa of the back surface is greater than or equal to 0.2 microns; the thickness of the supporting substrate is greater than or equal to twice the maximum grain size of the supporting substrate.

2. The support substrate according to claim 1, wherein: The surface roughness Sz of the back surface is greater than or equal to the average grain size of the support substrate.

3. The support substrate according to claim 1, wherein: The surface roughness Sa of the main supporting surface is less than or equal to 0.6 nanometers.

4. The support substrate according to claim 1, wherein: The warping degree of the support substrate is less than or equal to 200 micrometers.

5. The support substrate according to claim 1, wherein: The total thickness deviation of the main support surface is less than or equal to 1 micron.

6. The support substrate according to claim 1, wherein: The light transmittance of the support substrate in the wavelength range of 240-780 nm is less than 9%.

7. The support substrate according to claim 6, wherein: The light transmittance of the support substrate is less than 0.1% in a wavelength band below 550 nm.

8. The support substrate according to claim 1, wherein: The material of the support substrate is any one of polycrystalline magnesium aluminum spinel, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and polycrystalline quartz.

9. The support substrate according to claim 2, characterized in that: The surface roughness Sa of the main supporting surface is less than or equal to 0.6 nanometers.

10. The support substrate according to claim 2, wherein: The warping degree of the support substrate is less than or equal to 200 micrometers.

11. A method for preparing a supporting substrate, characterized in that: Used to prepare the support substrate according to any one of claims 1 to 10, the preparation method of the support substrate comprising: Using raw material crystal powder to form a crystal ingot, and processing the crystal ingot into a pre-processed substrate; performing polishing treatment on two opposite surfaces of the pre-treated substrate respectively; The supporting substrate is obtained by sandblasting one of the two polished surfaces of the pre-processed substrate; the supporting substrate has a main supporting surface for supporting the piezoelectric layer.

12. A composite substrate, characterized in that: It comprises a piezoelectric layer and a supporting substrate as described in any one of claims 1 to 10 or a supporting substrate prepared by the preparation method as described in claim 11; the piezoelectric layer is arranged on the main supporting surface of the supporting substrate.

13. An electronic device, characterized in that: Comprising the composite substrate as claimed in claim 12.

14. The electronic device according to claim 13, characterized in that: It also includes an IDT electrode, which is located on a main surface of the piezoelectric layer facing away from the supporting substrate.

15. The electronic device according to claim 14, characterized in that: The invention also includes an intermediate layer located between the support substrate and the piezoelectric layer, wherein a sound velocity of the intermediate layer is lower than a sound velocity of the piezoelectric layer.

16. The electronic device according to claim 15, characterized in that: The thickness of the intermediate layer is greater than or equal to 0.5λ, where λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode.

17. The electronic device according to claim 14, characterized in that: The thickness of the piezoelectric layer is less than or equal to 2λ, where λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode.

18. A module, characterized in that: An electronic device comprising a wiring substrate, a plurality of external connection terminals, an integrated circuit component, an inductor and a sealing portion, and the electronic device according to any one of claims 13 to 17.

Images