Substrate, electronic device, and module

Abstract

The embodiment of the invention provides a substrate, an electronic device and a module. The substrate provided by the embodiment of the invention comprises a polycrystalline material layer, the density of crystal grains in the polycrystalline material layer is greater than or equal to 1000 grains / mm < 2 >, and the thickness of the polycrystalline material layer is greater than or equal to two times of the maximum grain size of the crystal grains in the polycrystalline material layer. According to the supporting substrate with the special grain density, the high strength of the supporting substrate can be achieved, the situation that fragments occur due to insufficient strength can be reduced, and then the production quality and efficiency are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic device processing and manufacturing, and particularly to a substrate, an electronic device, and a module. Background Art

[0002] In some elastic wave filters, such as SAW (surface acoustic wave) devices, for example, in TC-SAW (temperature compensated SAW) devices, a composite substrate obtained by bonding a piezoelectric layer and a support substrate is required. The strength of the support substrate is one of the more important parameters in the production process of SAW devices. If the strength is insufficient, fragmentation is likely to occur in subsequent processing steps such as the bonding process and the process of fabricating electrodes on the composite substrate, which will affect production efficiency and quality, and even increase production costs. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem that the support substrate is prone to fragmentation due to insufficient strength. Therefore, the present invention provides a substrate, an electronic device, and a module, which can achieve higher strength and ensure production quality and efficiency.

[0004] An embodiment of the present invention provides a substrate, including a polycrystalline material layer, wherein the density of grains in the polycrystalline material layer is greater than or equal to 1000 grains / mm 2 , and the thickness of the polycrystalline material layer is greater than or equal to twice the maximum grain size in the polycrystalline material layer.

[0005] An embodiment of the present invention provides an electronic device, including the aforementioned substrate.

[0006] An 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 aforementioned electronic device.

[0007] The above embodiments of the present invention have at least one or more of the following beneficial effects: By providing a polycrystalline material layer with a special grain density setting, the substrate has better bending strength, which can avoid the occurrence of fragmentation problems in subsequent bonding processes and ensure production quality and efficiency. Brief Description of the Drawings

[0008] The following will describe in detail the specific embodiments of the present invention in conjunction with the drawings.

[0009] Figure 1 It is a schematic structural diagram of a support substrate provided by an embodiment of the present invention.

[0010] Figure 2 It is a microscopic tissue structure diagram of a support substrate provided by an embodiment of the present invention.

[0011] Figure 3 This is a schematic structural diagram of a composite substrate provided by an embodiment of the present invention.

[0012] Figure 4 This is a schematic structural diagram of an electronic device provided by an embodiment of the present invention.

[0013] Figure 5 This is a schematic structural diagram of another electronic device provided by an embodiment of the present invention.

[0014] Figure 6 This is a schematic structural diagram of yet another electronic device provided by an embodiment of the present invention.

[0015] Figure 7 This is a schematic structural diagram of still another electronic device provided by an embodiment of the present invention.

[0016] Figure 8 This is a schematic structural diagram of a module provided by an embodiment of the present invention.

[0017] Figure 9 This is a schematic diagram of a designated area when a yield test is performed on the electronic device provided by an embodiment of the present invention.

[0018]

Description of the Reference Numerals

[0019] 1000, module; 100, electronic device; 10, composite substrate; 11, support substrate; 111, main support surface; 112, back surface; 12, piezoelectric layer; 121, main surface; 13, intermediate layer; 20, electrode; 21, IDT electrode; 22, electrode pad; 30, encapsulation substrate; 41, first sealing structure; 42, second sealing structure; 51, bump; 52, first conductive part; 53, first external terminal electrode; 54, second conductive part; 55, second external terminal electrode; 60, gap; 70, cover body; 400, inductor; 500, sealing part; 600, integrated circuit component; 700, wiring substrate; 701, external connection terminal. Detailed Embodiments

[0020] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of the specific embodiments of the present invention with reference to the accompanying drawings.

[0021] To enable those of ordinary skill in the art to better understand the technical solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, 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 "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0023] 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 cross-referenced without conflict.

[0024]

First Embodiment

[0025] The first embodiment of the present invention provides a method for preparing a support substrate, which can obtain a support substrate having a main support surface for supporting a piezoelectric layer and a back surface opposite to the main support surface.

[0026] The method for preparing the support substrate includes:

[0027] Step S11: Making an ingot from raw material crystal powder and processing the ingot into a pre-treatment substrate;

[0028] Step S12: Polishing the two opposite surfaces of the pre-treatment substrate respectively;

[0029] Step S13: Performing sandblasting on one of the two polished surfaces of the pre-treatment substrate to obtain the support substrate.

[0030] The raw material crystal powder in step S11 is, for example, the powder of polycrystalline crystals, and the polycrystalline crystals are, for example, any one of polycrystalline magnesium aluminate spinel, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and polycrystalline quartz. In step S11, the raw material crystal powder can be made into an ingot through processes such as CIP (Cold Isostatic Pressing) and HIP (Hot Isostatic Pressing), and the pre-treatment substrate can be obtained through cutting, grinding and other processes.

[0031] For example, in step S12, the two opposite surfaces of the preprocessed substrate that are polished are respectively referred to as the first surface and the second surface. The first surface is used as the main support surface for supporting the piezoelectric layer in subsequent processes. In step S12, specifically, the first surface is polished to a surface roughness Sa less than or equal to 0.6 nm, so as to facilitate stable bonding with the piezoelectric layer in the subsequent process. According to the provisions in ISO 25178, 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. In this application, the surface roughness Sa is the arithmetic mean height Sa in ISO 25178.

[0032] In the first embodiment of the present invention, after the treatment in step S2, the TTV (Total Thickness Variation) of the surface of the preprocessed substrate can reach less than or equal to 1 micron, so as to better reduce the influence on the film thickness uniformity of the piezoelectric layer in subsequent processes.

[0033] As mentioned above, in step S13, the second surface of the preprocessed substrate is subjected to sandblasting treatment. After the sandblasting treatment, the second surface becomes the back surface of the support substrate. The grains on the second surface of the preprocessed substrate are broken through by sandblasting treatment to achieve roughening of the second surface, so that the surface roughness Sz of the back surface 112 of the support substrate can meet the target requirements. In this application, the surface roughness Sz is the maximum height Sz in ISO 25178.

[0034] In the first embodiment of the present invention, by first polishing the two opposite surfaces of the preprocessed substrate and then sandblasting the surface of the preprocessed substrate used to form the back surface of the support substrate to achieve roughening, a smaller TTV can be achieved through double-sided polishing treatment while reducing the light transmittance of the obtained support substrate, thus avoiding the problem of difficult alignment in subsequent processes while achieving a smaller TTV.

[0035] The first embodiment of the present invention also provides a method for preparing a composite substrate, which can be used to prepare a composite substrate. The composite substrate includes a piezoelectric layer and a support substrate. The piezoelectric layer is disposed on the support substrate. Specifically, the piezoelectric layer is disposed on the main support surface of the support substrate.

[0036] The method for preparing a composite substrate provided by the first embodiment of the present invention includes:

[0037] Step S11: Making an ingot from raw material crystal powder and processing the ingot into a preprocessed substrate;

[0038] Step S12: Polishing the two opposite surfaces of the preprocessed substrate respectively;

[0039] Step S14: Bonding the polished preprocessed substrate with a piezoelectric substrate;

[0040] Step S15: Perform sandblasting on the surface of the pre-treated substrate facing away from the piezoelectric substrate after the polishing treatment to obtain the composite substrate.

[0041] Among them, the specific steps of Step S11 and Step S12 can refer to the specific descriptions of Step S11 and Step S12 in the aforementioned preparation method of the support substrate. The piezoelectric substrate in Step S14 is, for example, a finished piezoelectric substrate obtained by cutting, grinding, polishing, and reduction treatment after making a lithium tantalate ingot from lithium tantalate material. Before Step S15, for example, Step S16 is further included. In Step S16, the piezoelectric substrate is subjected to thinning and polishing treatment to obtain a piezoelectric layer with a target film thickness. The thickness of the piezoelectric layer is, for example, 3 microns. According to the above description of Step S2, since the TTV of the pre-treated substrate through Step S12 can be less than or equal to 1 micron, the thickness of the piezoelectric layer obtained in Step S16 can be controlled to 3 ± 0.3 μm, that is, the thickness of the piezoelectric layer can be 2.7 to 3.3 microns. Step S15 can refer to the description in Step S13, except that Step S15 is performed after the combination of the polished pre-treated substrate and the piezoelectric substrate, while Step S13 is performed after the combination of the polished pre-treated substrate and the piezoelectric substrate. After the sandblasting treatment in Step S15, the pre-treated substrate becomes the above-mentioned support substrate, and the sandblasted surface becomes the back surface.

[0042] The preparation method of the composite substrate provided in the first embodiment of the present invention can achieve a smaller TTV through the double-sided polishing treatment in Step S12 and at the same time reduce the light transmittance of the obtained composite substrate through Step S15, thereby avoiding the problem of difficult alignment in subsequent processes while achieving a smaller TTV. Moreover, in the preparation method of the composite substrate provided in this first embodiment, after Step S14, since the back surface of the substrate has been subjected to sandblasting and roughening treatment and has an ideal roughness, there is no need to perform thinning treatment on the back surface of the pre-treated substrate or the formed support substrate 11, which can reduce the warpage of the support substrate and make the warpage of the support substrate in the composite substrate 10 less than or equal to 200 microns, providing a larger processing window for the subsequent packaging and testing.

[0043]

Second Embodiment

[0044] Before presenting the preparation method of the support substrate and the preparation method of the composite substrate in the first embodiment of the present application, in the process of preparing the composite substrate using a support substrate and a piezoelectric substrate, during the bonding process between the support substrate and the piezoelectric substrate, if the thickness of the support substrate is too thin, there is a problem that the wafer is prone to breakage during the bonding process. Therefore, in the existing process, a support substrate with a larger thickness is usually used to bond with the piezoelectric substrate, and then the back surface of the support substrate facing away from the piezoelectric substrate is thinned. However, there will be residual processing stress during thinning. If the remaining thickness of the support substrate is too thin, there will be a phenomenon of excessive warpage. Excessive warpage is likely to cause problems in the automatic operation during the encapsulation process. Therefore, in the existing process, the support substrate still retains a thickness of more than 300 μm after thinning and is difficult to be further thinned.

[0045] Therefore, based on the preparation method of the support substrate or the preparation method of the composite substrate provided in the first embodiment of the present application, in the preparation method of the composite substrate, it is no longer necessary to thin the support substrate, and a small warpage can be ensured. Therefore, a thinner support substrate can be prepared to bond with the piezoelectric layer. However, if a support substrate with a thickness less than 300 microns is directly prepared using the existing process, or if the existing support substrate is directly thinned to less than 300 microns for use, the strength of the support substrate is insufficient, and the wafer is extremely prone to breakage during the subsequent bonding process with the piezoelectric substrate and during the subsequent production process.

[0046] Therefore, the second embodiment of the present invention provides a support substrate 11 with higher strength. Figure 1 FIG. is a schematic structural diagram of the support substrate 11. Figure 2 FIG. is a microstructural diagram of a region in a support substrate 11 provided in the second embodiment of the present invention. Figure 2 The shown region is 50 microns * 50 microns.

[0047] The material of the support substrate 11 is, for example, a polycrystalline material, specifically any one of polycrystalline magnesium aluminate spinel, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and polycrystalline quartz. The support substrate 11 includes a plurality of grains. For example, the grain density of the grains in the support substrate 11 can be, for example, 1000 grains / mm 2 or more, 2000 grains / mm 2 or more, 20000 grains / mm 2 or more, 80000 grains / mm 2 or more, 250000 grains / mm 2 or more, and the minimum grain density is not less than 1000 grains / mm 2 . The corresponding grain boundary volume fraction is shown in Table 1. The grain density and the grain boundary volume fraction can be detected by an electron backscatter diffraction (EBSD) device. In this embodiment, the grain boundary volume fraction in the support substrate 11 is 8 - 40%.

[0048] In the embodiment of the present invention, the meaning of the grain density is to count the grains in an area on the surface of the support substrate 11. The total number N (unit: grains) of the grains in this area is divided by the area S (unit: square millimeter, mm 2 ) of this area, which is the density of the grains in the support substrate 11. The grain density is greater than or equal to 1000 grains / mm 2 That is, for the support substrate 11, N / S≥1000 grains per square millimeter is satisfied. During actual measurement, a larger-sized area in the microstructure diagram of the surface of the support substrate 11 can be divided into multiple smaller-sized areas (such as 50 microns * 50 microns) for counting respectively, and then the number of grains in multiple smaller-sized areas is summed up to obtain the total number of grains in the larger-sized area, from which the density of the grains can be obtained.

[0049] Among them, multiple grains in the support substrate 11 have different crystal orientations and are interconnected through grain boundaries. That is, the grain boundary is the interface between grains. The grain boundary volume can be understood as the volume of the gap between grains. The grain boundary volume ratio is the ratio of the grain boundary volume to the total volume of a certain area of the support substrate 11. In other words, the grain boundary volume can be understood as the difference between the total volume of this area and the total volume of multiple grains in this area. For example, for a certain area of the support substrate 11, the total volume is V0, and the sum of the volumes of multiple grains in the support substrate 11 is V1, then the grain boundary volume V2 is equal to V0 - V1. The grain boundary volume ratio is (V0 - V1) / V0. The volumes of multiple grains in the support substrate 11 can be measured by Electron Back Scatter Diffraction (EBSD for short). For example, the grain boundary volume ratio of the support substrate 11 (that is, the grain boundary volume fraction, specifically referring to the percentage of the grain boundary volume in the total volume of the material) can be 10%, 15%, 20%, 30%, 35%, 40%, etc. In this embodiment, by designing the value of the grain boundary volume in the support substrate 11, the support substrate 11 can achieve a more appropriate strength.

[0050] Refer to Figure 1 , the support substrate 11 includes a main support surface 111 and a back surface 112 opposite to the main support surface 111. The main support surface 111 is used to support the piezoelectric layer. The thickness of the support substrate 11 is the distance between the main support surface 111 and the back surface 112. Table 1 records the data of the grain density, grain boundary volume ratio, thickness, and corresponding flexural strength of some support substrates 11 provided in the second embodiment of the present invention. In this application, the flexural strength is measured by the test method specified in the flexural testing machine of Jinan Zhongchuang. Among them, the grain density generally has a fluctuation of about 10%.

[0051] Table 1:

[0052]

[0053] As can be seen from Table 1, when the grain density remains unchanged, the flexural strength increases with the increase of the thickness. Referring to the data corresponding to Experiment Nos. 1 to 3, when the grain density is about 200 grains / mm 2 and the proportion of the grain boundary volume is about 6%, if the flexural strength above 180 Mpa is to be achieved, the thickness needs to reach more than 300 microns. Referring to the data corresponding to Experiment Nos. 4 to 6, when the grain density is about 1000 grains / mm 2 and the proportion of the grain boundary volume is about 8%, when the thickness is 250 microns, the strength above 200 MPa can be achieved. Referring to the data in Experiment No. 12, when the grain density is about 20000 grains / mm 2 and the proportion of the grain boundary volume is about 8%, even when the thickness is reduced to 200 microns, the flexural strength of the support substrate 11 can still reach above 180 Mpa. Referring to the corresponding data of Experiment Nos. 3, 6, 9, 12, and 15, at the same thickness, when the grain density is about 80000 grains / mm 2 the flexural strength of the support substrate 11 can even reach above 200 Mpa. Therefore, the support substrate 11 provided by the second embodiment of the present invention has better flexural strength, can avoid the occurrence of chip breaking problems in the subsequent bonding process, and ensure the production quality and efficiency.

[0054] According to the experimental results in Table 1 above, in some embodiments, the thickness of the support substrate 11 is less than or equal to 300 microns. For example, the thickness of the support substrate 11 can be 300 microns, 250 microns, 200 microns, etc. More specifically, the thickness of the support substrate 11 is less than or equal to 200 microns. For example, 200 microns, 180 microns, 150 microns, etc. By setting the support substrate 11 to be thinner, better heat dissipation of the product can be achieved while ensuring the production quality.

[0055] In some embodiments, the flexural strength of the support substrate 11 provided in the present application is greater than or equal to 180 Mpa, which can prevent the occurrence of chip breaking problems. For example, the flexural strength of the support substrate 11 can be 180 Mpa, 200 Mpa, 250 Mpa, etc.

[0056] In some embodiments, the grain density in the support substrate is greater than or equal to 80000 grains / mm 2 , and the flexural strength of the support substrate 11 is greater than or equal to 200 Mpa, which can achieve better strength when the thickness of the support substrate 11 is made thinner, and can ensure the production quality while meeting the heat dissipation requirements of the product.

[0057] In some embodiments, the Young's modulus of the support substrate 11 is greater than or equal to 250 GPa. The Young's modulus is used to describe the ability of a material to resist deformation. When the Young's modulus of the support substrate 11 is greater than or equal to 250 GPa, it also has good strength.

[0058] In some embodiments, the grain size of the grains in the support substrate 11 can specifically be 10 microns or less.

[0059] The second embodiment of the present invention also provides a preparation method for preparing the above-mentioned support substrate 11, and this method includes:

[0060] Step S21: Prepare an ingot using crystal material powder with a particle size of 0.1 - 1 micron;

[0061] Step S22: Cut and grind the ingot to obtain a cut substrate;

[0062] Step S23: Polish the cut substrate to obtain the support substrate.

[0063] Among them, in step S21, the crystal material powder can be, for example, powder of polycrystalline materials such as polycrystalline magnesium aluminate spinel. In step S21, for example, through CIP (Cold Isostatic Pressing), the polycrystalline material powder is first made into a blank, and then through HIP (Hot Isostatic Pressing), the blank is processed into an ingot. The temperature of the CIP treatment is 1400 - 1500 °C, and the pressing pressure is 10000 - 100000 Psi (pounds per square inch). The temperature of the HIP treatment is 1650 - 1850 °C, and the ambient pressure is 150 - 250 Mpa. In step S22, the thickness of the cut substrate is, for example, 250 - 300 μm, and preferably silicon carbide or boron carbide powder with a particle size of 1200 - 1500 # (mesh) is used for grinding. In step S23, the polished surface is the surface for bonding with the piezoelectric layer. The surface roughness Sa of the surface for bonding with the piezoelectric layer (i.e., the main support surface 111) obtained in step S23 is ≤ 0.6 nm, TTV ≤ 2 μm, and the finished thickness of the finally obtained support substrate 11 is 200 - 250 μm.

[0064] That is, in some embodiments, the TTV of the main support surface 111 in the support substrate 11 is less than or equal to 2 microns. 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.

[0065] The method for preparing the support substrate 11 provided by the embodiments of the present invention can obtain the above-mentioned support substrate 11 by using crystal materials with special particle sizes, and can achieve appropriate strength even under the condition of a relatively thin thickness, which can ensure production efficiency and improve the yield of products.

[0066] In some embodiments, for example, the method for preparing the support substrate provided in the first embodiment can also be combined with the method for preparing the support substrate 11 in the second embodiment. For example, in step S32, both opposite surfaces of the cut substrate can be polished, and after the polishing process, the surface that will subsequently become the back surface 112 of the support substrate 11 is sandblasted to make the back surface 112 of the obtained support substrate 11 reach an appropriate roughness, so as to reduce the warpage of the support substrate 11.

[0067] Or in some other embodiments, it can also be that the surface for bonding with the piezoelectric layer is polished in step S32 to directly obtain the support substrate 11, and this embodiment is not limited.

[0068] When the method for preparing the support substrate provided in the first embodiment is combined with the method for preparing the support substrate 11 in the second embodiment, the obtained support substrate 11 can have the same effects as the support substrate preparation method provided in the first embodiment. Therefore, the support substrate 11 also has corresponding TTV, roughness Sz, warpage, light transmittance, etc.

[0069] For example, in some embodiments, the TTV of the main support surface 111 of the support substrate 11 can reach less than 1 micrometer.

[0070] For example, in some embodiments, the warpage of the support substrate 11 is less than or equal to 200 micrometers.

[0071] For example, in some embodiments, the light transmittance of the support substrate 11 in the wavelength band of 240 - 780 nm is less than 9%. Specifically, in the wavelength band below 550 nanometers, the light transmittance is less than 0.1%. This reduces the difficulty of the subsequent alignment process.

[0072] For example, in some embodiments, the surface roughness Sz of the back surface 112 of the support substrate 11 is greater than or equal to 3 micrometers, and the surface roughness Sa of the back surface 112 is greater than or equal to 0.2 micrometers. This can not only achieve a lower warpage but also effectively reflect and scatter body waves to avoid the appearance of noise.

[0073] For example, in some embodiments, the surface roughness Sz of the back surface 112 of the support substrate 11 is greater than or equal to the average grain size of the grains in the support substrate 11. For example, if the average grain size of the grains in the support substrate 11 is 3 micrometers, then the surface roughness Sz of the back surface 112 of the support substrate 11 is greater than or equal to 3 micrometers. For example, in some embodiments, the thickness of the support substrate 11 is greater than or equal to twice the maximum grain size in the support substrate. For example, if the maximum grain size in the support substrate 11 is 60 micrometers, then the thickness of the support substrate 11 is greater than or equal to 120 micrometers.

[0074] Refer to Figure 3The second embodiment of the present invention also provides a composite substrate 10, which includes a piezoelectric layer 12 and the support substrate 11 described in the foregoing second embodiment. The piezoelectric layer 12 is disposed on the support substrate 11. Specifically, the piezoelectric layer 12 is bonded to the main support surface 111 of the support substrate 11. The two can be directly bonded by van der Waals force. The piezoelectric layer 12 can be, for example, a lithium tantalate or lithium niobate material. By applying the foregoing support substrate 11, since the support substrate 11 has higher strength and is not easily fragmented, the yield of the composite substrate 10 is higher, and the support substrate 11 can achieve a relatively thin thickness, so the composite substrate 10 can also achieve a better heat dissipation effect.

[0075] Among them, the composite substrate 10 can be obtained, for example, by directly bonding the support substrate 11 and the piezoelectric layer 12. Alternatively, the support substrate 11 and the piezoelectric layer 12 can be surface-activated (activating the surfaces used for mutual bonding). After activation, they are butt-bonded in a normal-temperature vacuum environment. At this time, since the atoms on the surfaces of the support substrate 11 and the piezoelectric layer 12 will bond successfully to form covalent bonds after surface activation, the bonding strength is extremely high, and they are basically perfectly integrated, so a higher-quality composite substrate 10 can be obtained.

[0076] In some embodiments, after the support substrate 11 and the piezoelectric layer 12 are bonded, for example, the piezoelectric layer 12 is further thinned and polished to make the piezoelectric layer 12 thinner. At this time, the thickness of the piezoelectric layer 12 is, for example, 0.5 to 3.5 micrometers, which can be selected according to the applied frequency band. The piezoelectric layer 12 includes, for example, a main surface 121 facing away from the support substrate 11. After the piezoelectric layer 12 is thinned and polished, electrodes can be directly fabricated on the main surface 121 without further thinning the support substrate 11, which can reduce the process and save materials.

[0077] Refer to Figure 4 The second embodiment of the present invention also provides an electronic device 100, which includes the support substrate 11 in the foregoing embodiment or the composite substrate 10 in the foregoing embodiment. In the composite substrate 10, the electronic device 100 further includes, for example, an electrode 20 disposed on the main surface 121. The electrode 20 includes, for example, an IDT electrode 21. IDT is an interdigital transducer. The electronic device 100 is, for example, a SAW device. The electronic device 100 has the support substrate 11 in the foregoing embodiment. Since the support substrate 11 has higher strength and is not easily fragmented, the yield of the electronic device 100 is higher, and the support substrate 11 can achieve a relatively thin thickness, so the electronic device 100 can also achieve a better heat dissipation effect.

[0078] In some embodiments, in the electronic device 100, the density of the crystal grains in the support substrate 11 is greater than or equal to 20,000 grains / mm 2, the thickness of the support substrate 11 is 250 micrometers or less (≤250 micrometers).

[0079] Referring to Table 2, Table 2 shows the noise suppression situation in the electronic device 100 made of the support substrate 11 corresponding to the experiment numbers 1 to 18 in Table 1. The larger the noise suppression ratio, the better the noise suppression effect. When the noise suppression ratio reaches 100%, it means there is no noise influence. The data of the noise suppression ratio in Table 2 is derived from the yield obtained by performing performance sampling tests on the specified areas of the sample to be measured (electronic device 100). For example, the specified area is Figure 9 the 21 areas numbered 1 to 21 shown in. When the yield test results of these 21 areas are all qualified, the corresponding noise suppression ratio is 100%. Figure 9 The blue area in is the piezoelectric layer 12 in the electronic device 100.

[0080] Table 2:

[0081]

[0082]

[0083] Combining Table 1 and Table 2, for the data corresponding to the experiment numbers 1 to 3, when the grain density is around 200 grains / mm 2 , the grain boundary volume is small. When the filter is working, it cannot completely reflect the bulk wave, and there will be a certain amount of noise loss. For the data corresponding to the experiment numbers 4 to 6, when the grain density is around 1000 grains / mm 2 , the grain boundary volume reaches more than 8%. When the filter is working, it can basically completely reflect the bulk wave, and there will still be a little noise loss. For the data corresponding to the experiment numbers 10 to 18, when the grain density is 20000 grains / mm 2 or more, the grain boundary volume is large. When the filter is working, it completely reflects the bulk wave and there is no noise loss. When the bulk wave propagates through the grain boundary, there will be a certain amount of energy loss. When the support substrate has enough grain boundaries, the conduction of the bulk wave can be completely eliminated, and the noise can be reduced.

[0084] Referring to Figure 5 , in another embodiment of the present invention, the electronic device 100 (composite substrate 10) further includes an intermediate layer 13, and the intermediate layer 13 is located between the piezoelectric layer 12 and the support substrate 11. Among them, the sound velocity of the intermediate layer 13 is lower than that of the piezoelectric layer 12. That is, compared with the bulk wave propagating in the piezoelectric layer 12, the sound velocity of the bulk wave in the intermediate layer 13 is lower. In this embodiment, by setting the intermediate layer 13 with a low sound velocity, the sound velocity of the elastic wave can be decreased, and the energy of the elastic wave can be concentrated in the medium with a low sound velocity (i.e., the intermediate layer 13), which can reduce the loss and improve the Q value.

[0085] Among them, the material of the intermediate layer 13 is any one of silicon oxide, silicon oxynitride, tantalum oxide, or a material mainly composed of these materials. In some embodiments, the intermediate layer uses silicon oxide, 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, so that the absolute value of the TCF (temperature coefficient of drift) of the elastic wave device can be reduced. Further, the intrinsic acoustic impedance of silicon oxide is less than that of lithium tantalate, so the electromechanical coupling coefficient of the electronic component can be increased.

[0086] 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 micrometers, the thickness of the piezoelectric layer 12 is 0.1λ - 1λ, and the thickness of the intermediate layer 13 is 0.6λ.

[0087] The electronic device 100 provided in this embodiment can adopt CSP packaging (Chip Scale Package) or WLP packaging (Wafer Level Package).

[0088] For example, refer to Figure 6 , which is a schematic structural diagram of an electronic device 100 using CSP packaging. The electronic device 100 includes components (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 disposed opposite to the surface where the electrode 20 of the component is located (i.e., 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 disposed on the side of the packaging substrate 30 facing the component, covering the side surface and the surface of the component 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. The electrode pad 22 is electrically connected to a first conductive portion 52 in the wiring pattern on the packaging substrate 30 through a bump 51, and 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 electrical connection between the electronic device 100 and an external device can be achieved through the first external terminal electrode 53.

[0089] 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 existing CSP packaging. The electrode pad 22, the bump 51, the first conductive portion 52, and the first external terminal electrode 53 are all materials with good electrical conductivity. This embodiment is not limited to the above examples.

[0090] Reference Figure 7 , which is a schematic structural diagram of an electronic device 100 using a CSP package. The electronic device 100 includes components (including a composite substrate 10 and electrodes 20), a cover body 70, a second sealing structure 42, and second external terminal electrodes. The cover body 70 is disposed opposite to the surface of the component where the electrodes 20 are provided (i.e., the main surface 121 of the piezoelectric layer 12), and a gap 60 is formed between the cover body 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 provided is called an effective area. The second sealing structure 42 is disposed between the cover body 70 and the component and is disposed around the effective area. The second sealing structure 42 surrounds the electrode pad 22 to achieve sealing of the component. The second external terminal electrodes 55 provided on the surface of the cover body 70 facing away from the component are connected to the electrode pad 22 through a second conductive portion 54 passing through the cover body 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 electrodes 55.

[0091] Among them, the materials of the cover body 70 and the second sealing structure 42 can refer to the cover body materials and sealing materials used in the existing WLP package. The electrode pad 22, the second conductive portion 54, and the second external terminal electrodes 55 are all made of materials with good electrical conductivity, which is not limited in this embodiment.

[0092] Reference Figure 8 , the 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. The 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 the motherboard of a preset mobile communication terminal. The integrated circuit component 600 (which can be called 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. 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.

[0093] The module 1000 provided in this embodiment includes the electronic device 100, that is, includes the support substrate 11, and has the same effect as the support substrate 11, which will not be elaborated here.

[0094] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A substrate comprising a polycrystalline material layer, characterized in that: The density of the grains in the polycrystalline material layer is greater than or equal to 1000 grains / mm 2 , the thickness of the polycrystalline material layer is greater than or equal to twice the maximum grain size of the polycrystalline material layer.

2. A substrate according to claim 1, characterized in that: The bending strength of the polycrystalline material layer is greater than or equal to 180 MPa.

3. A substrate according to claim 1, characterized in that: The Young's modulus of the polycrystalline material layer is greater than or equal to 250 GPa.

4. A substrate according to claim 1, characterized in that: The light transmittance of the polycrystalline material layer in the wavelength range of 240-780 nm is less than 9%.

5. A substrate according to claim 1, characterized in that: The polycrystalline material layer has multiple grains with different crystal orientations, and the multiple grains are interconnected by grain boundaries. The grain boundary volume of a unit area is defined as the difference between the total volume of the unit area and the total volume of the multiple grains in the unit area. The grain boundary volume ratio is the ratio of the grain boundary volume in the unit area of ​​the polycrystalline material layer to the total volume of the unit area. The grain boundary volume ratio in the polycrystalline material layer is 8% to 40%.

6. A substrate according to claim 1, characterized in that: The surface roughness Sa of the back side of the polycrystalline material layer is greater than or equal to 0.2 micrometers.

7. A substrate according to claim 1, characterized in that: The surface roughness Sz of the back side of the polycrystalline material layer is greater than or equal to 3 microns.

8. A substrate according to any one of claims 1 to 7, characterized in that: Also included is a piezoelectric layer disposed on the polycrystalline material layer.

9. An electronic device, characterized in that: The invention comprises the substrate as claimed in claim 8.

10. The electronic device according to claim 9, characterized in that: It also includes an IDT electrode, which is located on a main surface of the piezoelectric layer facing away from the polycrystalline material layer.

11. The electronic device according to claim 10, 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.

12. The electronic device according to claim 9, characterized in that: The thickness of the polycrystalline material layer is less than 250 μm.

13. A module, characterized in that: An electronic device comprising a wiring substrate, a plurality of external connection terminals, an integrated circuit component and a sealing portion, and the electronic device according to any one of claims 9 to 12.

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