Composite substrate and method for manufacturing the same, electronic device, and module

Abstract

To provide a composite substrate which has both advantages of a temperature compensation type surface acoustic wave filter (TC-SAW) and a thin film type surface acoustic wave filter (TF-SAW), has high versatility, reduces difficulty in production, and is suitable for mass production, and to provide a method of manufacturing the same, an electronic device, and a module.SOLUTION: The composite substrate 100 includes a support layer 10 including a polycrystalline compound, and a piezoelectric layer 20 including a piezoelectric material and having a main bonding surface 21, wherein the piezoelectric layer is disposed on the support layer in a manner that the main bonding surface is bonded to the support layer, and has a diffusion region 22 extending from the main bonding surface into the piezoelectric layer in a direction gradually away from the support layer, wherein constituent elements of the polycrystalline compound include intrinsic elements different from constituent elements of the piezoelectric material, and the diffusion region includes at least one intrinsic element.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of electronic device processing and manufacturing technology, and more particularly to a composite substrate and a manufacturing method thereof, an electronic device, and a module. [Background technology]

[0002] High-performance high-frequency filters used in current communication systems typically include surface acoustic wave (SAW) resonators, bulk acoustic wave (BAW) resonators, thin-film bulk acoustic wave resonators (FBARs), and other acoustic resonators. Taking surface acoustic wave (SAW) resonators as an example, acoustic wave filters (SAW) can be divided into conventional surface acoustic wave filters (conventional SAW), temperature-compensated surface acoustic wave filters (TC-SAW), and thin-film surface acoustic wave filters (TF-SAW). By incorporating temperature compensation and thin-film technologies, their applicable frequency has increased to a maximum of 3.5 GHz compared to conventional SAW filters, and they are primarily used in the high-frequency front-end of mobile terminals, as well as base stations, automotive electronics, and the Internet of Things. Summary of the Invention [Problem to be solved by the invention]

[0003] The objective of the present invention is to provide a composite substrate, a manufacturing method thereof, and an electronic device, which not only can introduce a temperature compensation effect, but also can thin the piezoelectric layer, combine the advantages of TC-SAW and TF-SAW, is highly versatile, can reduce production difficulty, and is suitable for mass production. [Means for solving the problem]

[0004] One embodiment of the present invention provides a composite substrate, the composite substrate including: a support layer including a polycrystalline compound; and a piezoelectric layer including a piezoelectric material and having a bonding main surface, the piezoelectric layer being disposed on the support layer such that the bonding main surface is bonded to the support layer; the piezoelectric layer having a diffusion region extending from the bonding main surface in a direction gradually away from the support layer; the constituent elements of the polycrystalline compound including an intrinsic element different from the constituent elements of the piezoelectric material; and the diffusion region including at least one of the intrinsic elements.

[0005] One embodiment of the present invention provides a method for manufacturing a composite substrate, the method including: a preparation step of providing a support layer including a polycrystalline compound and having a supporting main surface; and a piezoelectric layer including a piezoelectric material and having a bonding main surface; and a bonding step of bonding the support layer and the piezoelectric layer together such that the bonding main surface is bonded to the supporting main surface to obtain a bonded substrate, wherein the method for manufacturing the composite substrate further includes a step of performing an activation treatment on the supporting main surface and the bonding main surface before the bonding step, so that after the bonding step, at least one element among the constituent elements of the polycrystalline compound diffuses from the support layer to the piezoelectric layer to form a diffusion region in the piezoelectric layer that extends from the bonding main surface in a direction gradually away from the support layer, thereby obtaining the composite substrate.

[0006] An embodiment of the present invention further provides an electronic device including the composite substrate described above or a composite substrate manufactured by the method for manufacturing a composite substrate described above.

[0007] One embodiment of the present invention further provides a module including a wiring substrate, a plurality of external connection terminals, an integrated circuit member, an inductor, a sealing portion, and the electronic device described above. [Effects of the Invention]

[0008] The above-described embodiments of the present invention have at least one or more of the following beneficial effects: By forming a diffusion region in the piezoelectric layer of the composite substrate, a filter device can be manufactured after thinning the piezoelectric layer of the composite substrate, and the electrical parameters of the filter device can essentially match those of conventional filter devices. The reduced TCF (Temperature Coefficient of Frequency) makes the filter device less susceptible to temperature effects and more stable performance. Therefore, the composite substrate provided in the above-described embodiments of the present invention not only introduces a temperature compensation effect, but also allows for a thin piezoelectric layer, combining the advantages of TC-SAW and TF-SAW, making it suitable for the production of both types of filters. Therefore, the composite substrate has the characteristics of being highly versatile and suitable for mass production, reducing the cost and difficulty of filter production. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a structure of a composite substrate according to an embodiment of the present invention. [Figure 2] 1 is a partially enlarged photograph of a composite substrate according to one embodiment of the present invention. [Figure 3] This is a further enlarged photograph of the area enclosed by the dashed line in Figure 2. [Figure 4] FIG. 3 is an analysis diagram of the content of tantalum element in a composite substrate according to one embodiment of the present invention. [Figure 5] FIG. 3 is an analysis diagram of the oxygen element content in a composite substrate according to one embodiment of the present invention. [Figure 6] FIG. 3 is an analysis diagram of the content of aluminum element in a composite substrate according to one embodiment of the present invention. [Figure 7] FIG. 3 is an analysis diagram of the magnesium element content in a composite substrate according to one embodiment of the present invention. [Figure 8] 3 is a flowchart of a method for manufacturing a composite substrate according to one embodiment of the present invention. [Figure 9] 1 is a schematic diagram illustrating the structure of an electronic device according to one embodiment of the present invention. [Figure 10]1 is a schematic diagram illustrating the structure of a module according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] (First Example) As shown in FIG. 1 , an embodiment of the present invention provides a composite substrate 100, which includes a support layer 10 and a piezoelectric layer 20 bonded together. The support layer 10 includes a polycrystalline compound and has a main support surface 11. The piezoelectric layer 20 includes a piezoelectric material and has a main bonding surface 21, and the piezoelectric layer 20 is disposed on the support layer 10 such that the main bonding surface 21 is bonded to the main support surface 11. The piezoelectric layer 20 includes a diffusion region 22 that extends from the main bonding surface 21 in a direction gradually away from the support layer 10. The constituent elements of the polycrystalline compound included in the support layer 10 include an inherent element that is different from the constituent elements of the piezoelectric material, and the diffusion region 22 includes at least one inherent element.

[0011] However, when the support layer 10 includes a polycrystalline compound, it may be understood that the main material of the support layer 10 is a polycrystalline compound, in other words, the support layer 10 is obtained by a polycrystalline compound. When the piezoelectric layer 20 includes a piezoelectric material, it may be understood that the main material of the piezoelectric layer 20 is a piezoelectric material, in other words, the piezoelectric layer 20 is obtained by a piezoelectric material. For example, the polycrystalline compound contained in the support layer 10 may be a polycrystalline spinel compound, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, aluminum oxynitride, etc. The piezoelectric material may be lithium tantalate (LT), lithium niobate (LN), etc. For example, the support layer 10 is a polycrystalline magnesium aluminum spinel substrate, the piezoelectric layer 20 is a lithium tantalate substrate, the support layer 10 includes polycrystalline magnesium aluminum spinel, magnesium, aluminum, and oxygen elements are the constituent elements of the polycrystalline magnesium aluminum spinel, tantalum, lithium, and oxygen elements are the constituent elements of the piezoelectric material, and the intrinsic elements are the magnesium and aluminum elements other than oxygen element in the constituent elements of the polycrystalline magnesium aluminum spinel, i.e., the diffusion region 22 includes at least one of the magnesium element and the aluminum element. The intrinsic elements in diffusion region 22 may be in an atomic or ionic state. Referring to the orientation shown in Figure 1, support surface 11 is the upper surface of support layer 10, bonding surface 21 is the lower surface of piezoelectric layer 20, piezoelectric layer 20 is disposed above support layer 10, and bonding surface 21 and support surface 11 are bonded to each other. Diffusion region 22 is located on the side of bonding surface 21 facing away from support layer 10, i.e., above bonding surface 21 in Figure 1.

[0012] Through experimental verification, the piezoelectric layer 20 of the composite substrate 100 according to the above embodiment was thinned to a thickness of 5 micrometers or less, and then the thin piezoelectric layer 20 was subjected to IDT (interdigital transducer) electrode processing to obtain a filter device. Electrical tests were then conducted on the filter device, and it was confirmed that several electrical parameters of the filter device in the electrical test results were basically equivalent to those of conventional filter devices, and that the TCF (temperature coefficient of frequency) reached -10 to -40 ppm / K. The filter device is less susceptible to temperature effects, and its performance is stable. Therefore, the composite substrate 100 provided in the above embodiment of the present invention can not only introduce a temperature compensation effect, but also thin the piezoelectric layer, combine the advantages of TC-SAW and TF-SAW, and be applicable to the production of two types of filters. Therefore, the composite substrate 100 has the characteristics of being highly versatile, suitable for mass production, and reducing the cost and difficulty of filter production.

[0013] In some embodiments, the thickness of the diffusion region 22 is 1 to 1000 nanometers, such as 1 nm, 5 nm, 10 nm, 20 nm, 40 nm, 100 nm, or 200 nm. Specifically, the thickness of the diffusion region 22 is 1 to 500 nm, more specifically, 1 to 100 nm, and even more specifically, 1 to 40 nm. The thickness of the diffusion region 22 is the stacking direction of the support layer 10 and the piezoelectric layer 20. The thickness of the diffusion region 22 is also called the diffusion depth. Within the above thickness range, the thicker the diffusion region 22, the higher its temperature compensation effect, which is advantageous in reducing temperature-related interference with the device. In particular, when the thickness of the diffusion region 22 is between 1 and 40 nm, there is a noticeable tendency for the temperature compensation effect to increase as the thickness increases.

[0014] In some embodiments, the polycrystalline compound of support layer 10 is selected from any one of polycrystalline spinel compounds, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and aluminum oxynitride.

[0015] In some embodiments, the polycrystalline compound of support layer 10 is a polycrystalline spinel compound, for example, the molecular formula of the polycrystalline spinel compound can be expressed as AB2O4, where A is a metal element, B is another metal element different from A, and O is elemental oxygen. For example, the polycrystalline compound is a polycrystalline magnesium aluminum spinel, whose chemical formula is MgAl2O4, where A is elemental magnesium and B is elemental aluminum.

[0016] One metal element in the polycrystalline spinel compound is referred to as the first metal element, and the other metal element is referred to as the second metal element; that is, the polycrystalline compound of support layer 10 is a polycrystalline spinel compound containing the first metal element, the second metal element, and oxygen, and in some embodiments, the first metal element and the second metal element are contained in diffusion region 22. For example, the constituent elements of the piezoelectric material of piezoelectric layer 20 include oxygen but do not include the first metal element or the second metal element, and both the first metal element and the second metal element are the inherent elements described above.

[0017] In some embodiments, the mass percentage of the first metal element in diffusion region 22 may be 1-20 wt%, specifically 1-10 wt%, and the mass percentage of the second metal element may be 1-20 wt%, specifically 1-10 wt%.

[0018] In some embodiments, when the metal activity of the first metal element is higher than the metal activity of the second metal element in the polycrystalline spinel compound, the difference in mass percentage between the first metal element and the second metal element in the diffusion region 22 is 1 to 5 wt%.

[0019] In one specific embodiment, the polycrystalline compound is polycrystalline magnesium aluminum spinel, the mass percentage of elemental magnesium in the diffusion region 22 is 1-10 wt %, and the mass percentage of elemental aluminum is 0.5-10 wt %.

[0020] In some embodiments, the constituent elements of the polycrystalline compound of support layer 10 include aluminum, the diffusion region 22 includes aluminum, and the mass percentage of aluminum in diffusion region 22 is 1-20 wt %, more specifically, the mass percentage of aluminum in diffusion region 22 is 1-10 wt %. For example, if the polycrystalline compound of support layer 10 is polycrystalline magnesium aluminum spinel (MgAlO), polycrystalline sapphire (AlO), polycrystalline aluminum nitride (AlN), or aluminum oxynitride (AlON), the diffusion region 22 includes aluminum, and the mass percentage of aluminum is 1-20 wt %.

[0021] In some embodiments, the polycrystalline compound of the support layer 10 includes nitrogen as an intrinsic element, the diffusion region 22 includes nitrogen, and the mass percentage of the nitrogen in the diffusion region 22 is 1-10 wt %, more specifically, the mass percentage of the nitrogen in the diffusion region 22 is 1-5 wt %. For example, the polycrystalline compound of the support layer 10 is polycrystalline aluminum nitride (AlN) or aluminum oxynitride (AlON), the diffusion region 22 includes nitrogen, and the mass percentage of the nitrogen in the diffusion region 22 is 1-10 wt %.

[0022] For example, the piezoelectric material of piezoelectric layer 20 is lithium tantalate or lithium niobate, the polycrystalline compound of support layer 10 is polycrystalline sapphire, the diffusion state of aluminum elements can be observed in diffusion region 22, and it is confirmed that the mass percentage of aluminum elements is 1 to 20 wt%. The polycrystalline compound of support layer 10 is polycrystalline aluminum nitride, the diffusion states of aluminum elements and nitrogen elements can be observed in diffusion region 22, and the mass percentage of aluminum elements is 1 to 20 wt% and the mass percentage of nitrogen elements is 1 to 10 wt%.

[0023] In some embodiments, in composite substrate 100, the conductivity of piezoelectric layer 20 is greater than 1×10 -12 ~1×10 -9The piezoelectric layer 20 may have a thickness of 150 to 250 micrometers, or may be thinned to a thickness of 5 micrometers or less. The support layer 10 may have a thickness of 250 to 500 micrometers, and after the electronic device 200 is manufactured using the composite substrate 100, the thickness of the support layer 10 in the electronic device 200 may be 150 to 250 micrometers.

[0024] (Second Example) An embodiment of the present invention further provides a method for manufacturing a composite substrate, the method comprising: a preparation step (step S1) of providing a support layer 10 comprising a polycrystalline compound and having a main support surface 11 and a piezoelectric layer 20 having a main bonding surface 21; a bonding step (step S3) of bonding the support layer 10 and the piezoelectric layer 20 together such that the bonding main surface 21 is bonded to the support main surface 11 to obtain a bonded substrate 101; However, the manufacturing method of the composite substrate further includes step S2 of performing an activation treatment on the supporting main surface 11 and the bonding main surface 21 before the bonding step S3, so that after the bonding step S3, at least one of the constituent elements of the polycrystalline compound diffuses into the piezoelectric layer 20, forming a diffusion region 22 in the piezoelectric layer 20 that extends from the bonding main surface 21 in a direction gradually away from the supporting layer 10, thereby obtaining the composite substrate 100.

[0025] The composite substrate manufacturing method provided in this embodiment can be used to manufacture the composite substrate 100 of the first embodiment described above. Specifically, the polycrystalline compound of the support layer 10 provided in step S1 may be selected from any one of polycrystalline spinel compounds, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and aluminum oxynitride. The piezoelectric material of the piezoelectric layer 20 may be lithium tantalate or lithium niobate. For specific arrangements of the polycrystalline compound of the support layer 10 and the piezoelectric material of the piezoelectric layer 20, please refer to the description of the first embodiment described above.

[0026] In step S1, the thickness of the support layer 10 is 250 to 500 micrometers, and the thickness of the piezoelectric layer 20 is 150 to 250 micrometers. Before step S1, for example, the materials of the support layer 10 and the piezoelectric layer 20 are polished so that the surface roughness Sa of the main support surface 11 and the main bonding surface 21 is 0.5 nm or less. Before step S3, for example, the electrical conductivity of the main bonding surface 21 is 1×10 -12 ~1×10 -9 The surface of the piezoelectric layer 20 is further subjected to a reduction treatment so that a large number of oxygen vacancies are present, with a density of siemens / centimeter (S / m).

[0027] Step S2 can refer to step (a) in Figure 8, specifically, Ar (argon) ions are emitted using an ion gun 300 to activate the supporting surface 11 and the bonding surface 21, and after step S2, step S3 is performed with reference to step (b) in Figure 8 to obtain a bonded substrate 101. Because the surface of the piezoelectric layer 20 has a large number of oxygen vacancies, active atoms or ions on the surface of the supporting layer 10 can easily diffuse into the piezoelectric layer 20, forming a diffusion region 22, and finally forming a composite substrate 100 as shown in step (c) in Figure 8.

[0028] In some specific embodiments, the constituent elements of the polycrystalline compound of the support layer 10 include an intrinsic element different from the constituent elements of the piezoelectric material of the piezoelectric layer 20, and the diffusion region 22 includes at least one intrinsic element.

[0029] In some embodiments, the method for manufacturing a composite substrate further includes step S4 of annealing the bonded substrate 101 after the bonding process. The annealing temperature is, for example, 100-300°C. The annealing can accelerate the formation of the diffusion region 22 and help the diffusion region 22 reach an appropriate diffusion depth (thickness), thereby making it possible to control the thickness of the diffusion region 22 and ensure consistency of the diffusion depth in mass production. Specifically, step S4 employs a low-temperature, oxygen-free annealing process, and the oxygen-free environment can prevent resistance changes in the piezoelectric layer 20 during the annealing process.

[0030] 8, in some embodiments, the manufacturing method of the composite substrate further includes, after the bonding step S3, a step S5 of thinning the piezoelectric layer 20 so that the thickness of the piezoelectric layer 20 is 5 micrometers or less (less than or equal to 5 micrometers). However, if step S4 is further included after step S3, step S5 is performed after step S4. By thinning and polishing the piezoelectric layer 20 in step S5, the piezoelectric layer 20 can be thinned, which can facilitate the manufacturing of the TF-SAW device.

[0031] 2 to 7 show the results of observations of a composite substrate 100 manufactured using the manufacturing method provided in this embodiment in one specific example. In this specific example, the piezoelectric material of piezoelectric layer 20 is lithium tantalate (chemical formula: LiTaO, abbreviated as LT), and the polycrystalline compound of support layer 10 is magnesium aluminum spinel. In FIG. 2, the dashed lines indicate the regions on both sides of the interface between support layer 10 and piezoelectric layer 20. In FIG. 3, the dashed line area in FIG. 2 is further enlarged to reveal a diffusion region 22 (the region surrounded by a black solid line in FIG. 3) with a length of approximately 5 nm. The upper right corner of FIG. 3 (scale: 1 / 5 nanometers) shows the atomic state of diffusion region 22 when subjected to high-magnification STEM observation. The uniform atomic arrangement is clearly visible. Therefore, diffusion region 22 is a crystalline layer, not an amorphous layer. This crystalline layer structure facilitates smoother heat conduction between diffusion region 22 and the non-diffusion region (i.e., the region other than the diffusion region of piezoelectric layer 20), which is advantageous for improving TCF. As can be seen, the main component of the diffusion region 22 is still the piezoelectric material of the piezoelectric layer 20, and only a portion of the elements diffuse from the support layer 10 into the piezoelectric layer 20 to form the diffusion region 22. Elemental analysis was performed on both sides of the interface along the direction indicated by the black arrow in FIG. 3 (i.e., the direction from LT to Spinel). As shown in FIG. 4, there is no diffusion of Ta (tantalum) atoms, and a clear boundary exists between LT and Spinel. The diffusion status of O (oxygen) atoms cannot be determined from FIG. 5. As shown in FIG. 6, a low concentration of aluminum elements is diffused into LT to a depth of 1 to 1000 nm, and the mass percentage of aluminum elements in the diffusion region 22 is measured to be 0.5 to 10 wt%. As shown in FIG. 7, a medium concentration of magnesium elements is diffused into LT to a depth of 1 to 1000 nm, and the mass percentage of magnesium elements in the diffusion region 22 is measured to be 1 to 10 wt%. As a result, the composite substrate manufacturing method provided in the second embodiment of the present invention can manufacture the composite substrate 100 provided in the first embodiment described above.

[0032] Table 1 shows data on the diffusion depth and mass percentage of magnesium and aluminum elements in diffusion region 22 in composite substrate 100 (where the polycrystalline compound of support layer 10 is magnesium aluminum spinel) in several embodiments. According to Table 1, when the diffusion depth is 40 nm or less, the mass percentage of magnesium and aluminum increases as the diffusion depth increases, and when the diffusion depth is greater than 40 nm, the mass percentage of magnesium and aluminum gradually decreases as the diffusion depth increases, allowing for a diffusion region 22 with a maximum thickness of 1000 nm to be formed.

[0033] [Table 1]

[0034] The effects of the composite substrate 100 manufactured by the composite substrate manufacturing method are described below in Experiments 1 to 4. In Experiment 1, it was ensured that only a small number of atoms or ions were activated and bonded on the surfaces of the piezoelectric layer 20 and the support layer 10. An IDT electrode was fabricated on the resulting composite substrate 100 and used for electrical testing of a filter. In Experiment 2, it was ensured that only a portion of the atoms or ions were activated and bonded on the surfaces of the piezoelectric layer 20 and the support layer 10. An IDT electrode was fabricated on the resulting composite substrate 100 and used for electrical testing of a filter. In Experiment 3, it was ensured that a large number of atoms or ions were activated and bonded on the surfaces of the piezoelectric layer 20 and the support layer 10. An IDT electrode was fabricated on the resulting composite substrate 100 and used for electrical testing of a filter. In Experiment 4, it was ensured that most of the atoms or ions were activated and bonded on the surfaces of the piezoelectric layer 20 and the support layer 10. An IDT electrode was fabricated on the resulting composite substrate 100 and used for electrical testing of a filter.

[0035] The results of the electrical tests for Experiments 1 to 4 are shown in Table 2.

[0036] [Table 2]

[0037] In Table 2, the frequency difference refers to the difference between the filter's receiving frequency and the designed standard frequency, and the insertion loss difference refers to the difference between the receiving and transmitting insertion losses. The data from Experiments 1 to 4 show that the thickness of the diffusion region 22 (i.e., the diffusion depth of the magnesium and aluminum elements) does not significantly affect the electrical parameters, and both meet the requirements of conventional TC-SAW and TF-SAW. Increasing the thickness of the diffusion region 22 significantly optimizes the TCF. After metal ions are diffused into the piezoelectric layer 20, oxygen vacancies on the surface of the piezoelectric layer 20 are replenished, significantly improving its thermal conductivity and electrical conductivity, thereby improving the filter device's TCF characteristics. Increasing the thickness of the diffusion region 22 reduces temperature-induced interference with the filter device and contributes to stable performance. Therefore, the composite substrate 100 fabricated using the above method not only achieves temperature compensation, but also allows for a thinner piezoelectric layer 20, combining the advantages of both TC-SAW and TF-SAW.

[0038] (Third Example) A third embodiment of the present invention provides an electronic device 200, which includes any one of the composite substrates 100 in the first embodiment described above or a composite substrate 100 manufactured by the composite substrate manufacturing method in the second embodiment described above. For a detailed description of the composite substrate 100, please refer to the descriptions of the first and second embodiments described above, and further description will be omitted here. The electronic device 200 further includes, for example, an electrode 30 arranged on the side of the piezoelectric layer 20 farther from the support layer 10. See FIG. 9, where the electrode 30 is, for example, an IDT electrode, and the electronic device 200 is, for example, a SAW device.

[0039] In some embodiments, electrical testing is performed on the electronic device 200, and the temperature drift coefficient of the electronic device 200 is −10 to −40 ppm / K.

[0040] The electronic device 200 provided in the third embodiment of the present invention includes the composite substrate 100 of the first and second embodiments described above, and has the same beneficial effects as the first and second embodiments described above, and the description thereof will be omitted here.

[0041] Referring to FIG. 10 , a third embodiment of the present invention further provides a module 1000 including a wiring substrate 700, a plurality of external connection terminals 701, an integrated circuit member 600, an electronic device 200 (including a composite substrate 100), an inductor 400, and an encapsulation unit 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 attached to a motherboard of a predetermined mobile communication terminal. The integrated circuit member 600 (which may also be referred to as an IC) is attached inside the wiring substrate 700. The integrated circuit member 600 includes a switch circuit and a low-noise amplifier. The electronic device 200 is attached to a 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). The encapsulation unit 500 is used to encapsulate the plurality of electronic members including the electronic device 200 on the wiring substrate 700.

[0042] The module 1000 provided in this embodiment includes the electronic device 200 and has the same beneficial effects as the electronic device 200, so the description thereof will be omitted here.

[0043] The above are only preferred embodiments of the present invention and do not limit the present invention in any manner. Although the preferred embodiments have disclosed the present invention as above, they do not limit the present invention. Those skilled in the art can make equivalent embodiments with slight changes or modifications that are equivalent changes using the technical content disclosed above, within the scope of the technical solutions of the present invention. Any simple amendments, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention all fall within the scope of the technical solutions of the present invention. [Explanation of symbols]

[0044] 10 Support layer 11 Main support surface 20 Piezoelectric layer 21 Bonding surface 22 Diffusion Region 30 electrodes 100 Composite Board 101 Bonded substrate 200 Electronic Devices 300 Ion Gun 400 inductor 500 Sealing part 600 Integrated circuit components 700 wiring board 701 External connection terminal 1000 Module

Claims

1. a support layer comprising a polycrystalline compound; a piezoelectric layer including a piezoelectric material and having a bonding main surface, the piezoelectric layer being disposed on the support layer in such a manner that the bonding main surface is bonded to the support layer, the piezoelectric layer having a diffusion region extending in a direction gradually away from the bonding main surface and away from the support layer, the constituent elements of the polycrystalline compound including an intrinsic element different from the constituent elements of the piezoelectric material, and the diffusion region including at least one of the intrinsic elements.

2. 2. The composite substrate of claim 1, wherein the diffusion region has a thickness of 1 to 1000 nanometers.

3. 2. The composite substrate according to claim 1, wherein the polycrystalline compound is selected from the group consisting of a polycrystalline spinel compound, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and aluminum oxynitride.

4. The composite substrate described in claim 3, characterized in that the polycrystalline compound is a polycrystalline spinel compound containing a first metal element, a second metal element, and an oxygen element, and the first metal element and the second metal element are contained within the diffusion region.

5. 5. The composite substrate according to claim 4, wherein the mass percentage of the first metal element in the diffusion region is 1 to 20 wt %, and the mass percentage of the second metal element is 1 to 20 wt %.

6. The difference in mass percentage between the first metal element and the second metal element in the diffusion region is 1 to 5 wt%, and the metal activity of the first metal element is higher than the metal activity of the second metal element.

7. 4. The composite substrate of claim 3, wherein the polycrystalline compound is polycrystalline magnesium aluminum spinel, and the mass percentage of elemental magnesium in the diffusion region is 1-10 wt %, and the mass percentage of elemental aluminum is 0.5-10 wt %.

8. 2. The composite substrate according to claim 1, wherein the intrinsic element includes an aluminum element, and the mass percentage of the aluminum element in the diffusion region is 1 to 20 wt %.

9. 2. The composite substrate of claim 1, wherein the diffusion region is a crystalline layer.

10. 10. The composite substrate according to claim 1, wherein the piezoelectric material is lithium tantalate or lithium niobate, and / or the thickness of the piezoelectric layer is 5 micrometers or less.

11. An electronic device comprising the composite substrate according to any one of claims 1 to 10.

12. 12. The electronic device according to claim 11, wherein the temperature drift coefficient of the electronic device is −10 to −40 ppm / K.

13. A module comprising a wiring substrate, a plurality of external connection terminals, an integrated circuit member, an inductor, a sealing portion, and the electronic device according to claim 11 or 13.

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