Composite substrate and preparation method thereof, electronic device and module

Abstract

The embodiment of the invention provides a composite substrate and a preparation method thereof, an electronic device and a module, and the composite substrate comprises a supporting layer which comprises a polycrystalline compound; the piezoelectric layer is formed on the supporting layer, and the piezoelectric layer is provided with a diffusion region which extends from the lower surface, close to the supporting layer, of the piezoelectric layer in the direction gradually away from the supporting layer; wherein the piezoelectric layer comprises a piezoelectric material, the constituent elements of the polycrystalline compound comprise characteristic elements different from the constituent elements of the piezoelectric material, and the diffusion region is based on the piezoelectric material and comprises at least one characteristic element; the piezoelectric material has at least one element different from a constituent element of the polycrystalline compound, and the element is only located in the piezoelectric layer. The composite substrate provided by the embodiment of the invention has the advantages of a TC-SAW and a TF-SAW, is high in universality, can reduce the production difficulty, and is suitable for batch production.

Description

Technical Field

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

[0002] High-performance RF filters used in current communication systems usually include surface acoustic wave (SAW) resonators, bulk acoustic wave (BAW) resonators, thin film bulk acoustic wave resonators (FBAR) and other types of acoustic resonators. Taking surface acoustic wave (SAW) resonators as an example, acoustic wave filters (SAW) are divided into ordinary surface acoustic wave filters (ordinary SAW), temperature compensated surface acoustic wave filters (TC-SAW) and thin film surface acoustic wave filters (TF-SAW). By introducing temperature compensation technology and thin film technology, its applicable frequency can be increased to a maximum of 3.5GHz compared to ordinary SAW. It is mainly used in mobile RF front-ends, as well as base stations, automotive electronics and the Internet of Things. Summary of the invention

[0003] The purpose of the present invention is to provide a composite substrate, a preparation method thereof and an electronic device. The composite substrate can not only introduce temperature compensation effect, but also thin the piezoelectric layer. It has the advantages of TC-SAW and TF-SAW, has high versatility, can reduce production difficulty, and is suitable for mass production.

[0004] One embodiment of the present invention provides a composite substrate, comprising: a support layer, the support layer comprising a polycrystalline compound; a piezoelectric layer, the piezoelectric layer being formed on the support layer, the piezoelectric layer having a diffusion zone extending from its lower surface close to the support layer toward a direction gradually away from the support layer; wherein the piezoelectric layer comprises a piezoelectric material, the constituent elements of the polycrystalline compound comprising characteristic elements different from the constituent elements of the piezoelectric material, the diffusion zone being based on the piezoelectric material and comprising at least one of the characteristic elements; the piezoelectric material having at least one element different from the constituent elements of the polycrystalline compound, the element being located only in the piezoelectric layer.

[0005] One embodiment of the present invention provides a method for preparing a composite substrate, comprising: providing a support layer, the support layer comprising a polycrystalline compound; forming a piezoelectric layer on the support layer to obtain the composite substrate; the piezoelectric layer comprising a piezoelectric material, the constituent elements of the polycrystalline compound comprising characteristic elements different from the constituent elements of the piezoelectric material; activating the surfaces of the support layer and the piezoelectric material before forming the piezoelectric layer; so that at least one of the characteristic elements can diffuse unidirectionally from the support layer into the piezoelectric material, so as to form a diffusion zone in the piezoelectric layer extending from its lower surface close to the support layer toward a direction gradually away from the support layer, the diffusion zone is based on the piezoelectric material and comprises at least one of the characteristic elements, and the piezoelectric material has at least one element different from the constituent elements of the polycrystalline compound, and the element is only located in the piezoelectric layer.

[0006] An embodiment of the present invention further provides an electronic device, comprising the aforementioned composite substrate or a composite substrate manufactured by the aforementioned composite substrate manufacturing method.

[0007] One embodiment of the present invention also provides a module including a wiring substrate, a plurality of external connection terminals, an integrated circuit component, an inductor, and a sealing portion, as well as the aforementioned electronic device.

[0008] The above embodiments of the present invention have at least one or more of the following beneficial effects: a diffusion zone is formed in the piezoelectric layer of the composite substrate, so that the piezoelectric layer of the composite substrate can be thinned to obtain a filter device, and the electrical parameters of the filter device can basically reach the parameters of the traditional filter device, and the TCF it possesses can reduce the interference of the filter device by temperature and maintain stable performance. Therefore, the composite substrate provided by the above embodiments of the present invention can not only introduce temperature compensation, but also thin the piezoelectric layer, and has the advantages of both TC-SAW and TF-SAW. Moreover, since it can be applied to the production of two types of filters, the composite substrate has the characteristics of high versatility, suitable for mass production, and reduced filter production cost and difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The specific implementation modes of the present invention will be described in detail below with reference to the accompanying drawings.

[0010] Figure 1 A schematic structural diagram of a composite substrate provided in an embodiment of the present invention.

[0011] Figure 2 This is a partially enlarged photograph of a composite substrate provided in one embodiment of the present invention.

[0012] Figure 3 for Figure 2 A further enlarged photo of the dotted frame in the middle.

[0013] Figure 4 This is an analysis chart of the tantalum content in a composite substrate provided in one embodiment of the present invention.

[0014] Figure 5 This is an analysis chart of the oxygen content in a composite substrate provided in one embodiment of the present invention.

[0015] Figure 6 This is an analysis chart of the aluminum content in a composite substrate provided in one embodiment of the present invention.

[0016] Figure 7 This is an analysis chart of the magnesium content in a composite substrate provided in one embodiment of the present invention.

[0017] Figure 8 A schematic flow chart of a method for preparing a composite substrate provided in accordance with an embodiment of the present invention.

[0018] Fig. 9 A schematic structural diagram of an electronic device provided in one embodiment of the present invention.

[0019] Fig.10 A schematic diagram of the structure of a module provided for one embodiment of the present invention.

[0020] [Description of Reference Numerals]

[0021] 100. Composite substrate; 101. Bonded substrate; 10. Support layer; 11. Support main surface; 20. Piezoelectric layer; 21. Bonding main surface; 22. Diffusion region; 30. Electrode; 200. Electronic device; 300. Ion gun; 400. Inductor; 500. Sealing part; 600. Integrated circuit component; 700. Wiring substrate; 701. External connection terminal; 1000. Module. 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] [First embodiment]

[0027] like Figure 1 As shown, an embodiment of the present invention provides a composite substrate 100, comprising a support layer 10 and a piezoelectric layer 20 bonded to each other. The support layer 10 comprises a polycrystalline compound and has a support main surface 11. The piezoelectric layer 20 comprises a piezoelectric material and has a bonding main surface 21, and the piezoelectric layer 20 is arranged on the support layer 10 in a manner that the bonding main surface 21 is bonded to the support main surface 11. The piezoelectric layer 20 comprises a diffusion zone 22 extending from the bonding main 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 characteristic elements different from the constituent elements of the piezoelectric material, and the diffusion zone 22 includes at least one characteristic element.

[0028] Among them, the support layer 10 includes a polycrystalline compound, which can also be understood as 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. The piezoelectric layer 20 includes a piezoelectric material, which can be understood as 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 included in the support layer 10 can be a polycrystalline spinel compound, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, aluminum oxynitride, etc. The piezoelectric material can 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 are the constituent elements of the polycrystalline magnesium aluminum spinel, tantalum, lithium and oxygen are the constituent elements of the piezoelectric material, and the characteristic element is the magnesium element and aluminum element in the constituent elements of the polycrystalline magnesium aluminum spinel except the oxygen element, that is, the diffusion region 22 includes at least one of the magnesium element and the aluminum element. The characteristic element in the diffusion region 22 can be in an atomic or ionic state. Figure 1 In the orientation shown, the supporting main surface 11 is the upper surface of the supporting layer 10, the bonding main surface 21 is the lower surface of the piezoelectric layer 20, the piezoelectric layer 20 is arranged above the supporting layer 10, and the bonding main surface 21 and the supporting main surface 11 are bonded to each other. The diffusion region 22 is located on the side of the bonding main surface 21 facing away from the supporting layer 10, that is, Figure 1 The upper side of the bonding main surface 21 is provided.

[0029] After experimental verification, the piezoelectric layer 20 of the composite substrate 100 provided in the above embodiment is thinned to less than 5 microns to form a thin film, and then the IDT (interdigital transducer) electrode processing is performed on the thin film piezoelectric layer 20 to obtain a filter device. The filter device is electrically tested. In the electrical test results, some electrical parameters of the filter device can basically reach the parameters of the traditional filter device, and the TCF (temperature drift coefficient) can reach -10 to -40ppm / K, which is conducive to reducing the interference of the filter device by temperature and maintaining stable performance. Therefore, the composite substrate 100 provided in the above embodiment of the present invention can not only introduce temperature compensation, but also thin the piezoelectric layer, and has the advantages of both TC-SAW and TF-SAW. Moreover, since it can be applied to the production of two types of filters, the composite substrate 100 has the characteristics of high versatility, suitable for mass production, and reduced filter production cost and difficulty.

[0030] In some embodiments, the thickness of the diffusion region 22 is 1 to 1000 nanometers, for example, 1 nm, 5 nm, 10 nm, 20 nm, 40 nm, 100 nm or 200 nm, etc. Specifically, the thickness of the diffusion region 22 is 1 to 500 nm, more specifically, the thickness of the diffusion region 22 is 1 to 100 nm, and more specifically, the thickness of the diffusion region 22 is 1 to 40 nm. The thickness direction 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 can also be called the diffusion depth. Within the above thickness range, the greater the thickness of the diffusion region 22, the better the temperature compensation effect, which is more conducive to reducing the interference of the device by temperature. In particular, when the thickness of the diffusion region 22 is between 1 and 40 nm, the greater the thickness, the more obvious the trend of increasing the temperature compensation effect.

[0031] In some embodiments, the polycrystalline compound of the support layer 10 is selected from any one of polycrystalline spinel compounds, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and aluminum oxynitride.

[0032] In some embodiments, the polycrystalline compound of the support layer 10 is a polycrystalline spinel compound. For example, the molecular formula of the polycrystalline spinel compound can be expressed as AB2O4, wherein A is a metal element, B is another metal element different from A, and O is an oxygen element. For example, the polycrystalline compound is polycrystalline magnesium aluminum spinel, and its chemical formula is MgAl2O4, then A is magnesium element, and B is aluminum element.

[0033] One metal element in the polycrystalline spinel compound is called the first metal element, and the other metal element is called the second metal element, that is, the polycrystalline compound of the support layer 10 is a polycrystalline spinel compound including the first metal element, the second metal element and the oxygen element. In some embodiments, the first metal element and the second metal element are included in the diffusion region 22. For example, the constituent elements of the piezoelectric material of the piezoelectric layer 20 include the oxygen element but do not include the first metal element and the second metal element, and the first metal element and the second metal element are both the aforementioned characteristic elements.

[0034] In some embodiments, the mass percentage of the first metal element in the diffusion region 22 is 1-20 wt%, specifically 1-10 wt%. The mass percentage of the second metal element is 1-20 wt%, specifically 1-10 wt%.

[0035] In some embodiments, in the polycrystalline spinel compound, the metal activity of the first metal element is higher than that of the second metal element, and the difference in mass percentage between the first metal element and the second metal element in the diffusion region 22 is 1-5 wt %.

[0036] In a specific embodiment, the polycrystalline compound is polycrystalline magnesium-aluminum spinel, the mass percentage of magnesium in the diffusion region 22 is 1-10 wt %, and the mass percentage of aluminum is 0.5-10 wt %.

[0037] In some embodiments, the characteristic element in the constituent elements of the polycrystalline compound of the support layer 10 includes aluminum, the diffusion region 22 includes aluminum, and the mass percentage of the aluminum in the diffusion region 22 is 1-20wt%, more specifically, the mass percentage of the aluminum in the diffusion region 22 is 1-10wt%. For example, when the polycrystalline compound of the support layer 10 is polycrystalline magnesium aluminum spinel (MgAl2O4), polycrystalline sapphire (Al2O3), polycrystalline aluminum nitride (AlN) or aluminum oxynitride (AlON), the diffusion region 22 includes aluminum and the mass percentage of the aluminum is 1-20wt%.

[0038] In some embodiments, the characteristic element in the constituent elements of the polycrystalline compound of the support layer 10 includes nitrogen, the diffusion region 22 includes nitrogen, the mass percentage of the nitrogen in the diffusion region 22 is 1-10wt%, and more specifically, the mass percentage of the nitrogen in the diffusion region 22 is 1-5wt%. 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 is 1-10wt%.

[0039] For example, the piezoelectric material of the piezoelectric layer 20 is lithium tantalate or lithium niobate, the polycrystalline compound of the support layer 10 is polycrystalline sapphire, the diffusion of aluminum can be observed in the diffusion region 22 and the mass percentage of aluminum is calculated to be 1-20wt%. The polycrystalline compound of the support layer 10 is polycrystalline aluminum nitride, the diffusion of aluminum and nitrogen can be observed in the diffusion region 22 and the mass percentage of aluminum is calculated to be 1-20wt% and the mass percentage of nitrogen is calculated to be 1-10wt%.

[0040] In some embodiments, in the composite substrate 100, the conductivity of the piezoelectric layer 20 is 1×10 -12 ~1×10 -9 S / cm (Siemens / cm). The thickness of the piezoelectric layer 20 can be 150 to 250 microns, and the piezoelectric layer 20 can be thin-filmed, and the thickness of the piezoelectric layer 20 after thin-filming is less than or equal to 5 microns. The thickness of the support layer 10 is 250 to 500 microns. After the electronic device 200 is prepared using the composite substrate 100, the thickness of the support layer 10 in the electronic device 200 can be 150 to 250 microns.

[0041] [Second embodiment]

[0042] The embodiment of the present invention further provides a method for preparing a composite substrate, comprising:

[0043] Preparation process (step S1 ): providing a support layer 10 and a piezoelectric layer 20 , wherein the support layer 10 includes a polycrystalline compound and has a support main surface 11 ; and the piezoelectric layer 20 has a bonding main surface 21 .

[0044] Bonding process (step S3): bonding the support layer 10 and the piezoelectric layer 20 together in a manner that the bonding main surface 21 is bonded to the support main surface 11 to obtain a bonded substrate 101;

[0045] Among them, the preparation method of the composite substrate also includes step S2: activating the supporting main surface 11 and the bonding main surface 21 before the bonding process S3; so that after the bonding process S3, at least one element among the constituent elements of the polycrystalline compound can diffuse into the piezoelectric layer 20, so that a diffusion zone 22 is formed in the piezoelectric layer 20, extending from the bonding main surface 21 in a direction gradually away from the supporting layer 10, to obtain a composite substrate 100.

[0046] The preparation method of the composite substrate provided in this embodiment can be used to prepare the composite substrate 100 of the aforementioned first embodiment. Specifically, the polycrystalline compound of the support layer 10 provided in step S1 can be selected from any one of a polycrystalline spinel compound, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and aluminum oxynitride. The piezoelectric material of the piezoelectric layer 20 can be lithium tantalate or lithium niobate. The specific settings of the polycrystalline compound of the support layer 10 and the piezoelectric material of the piezoelectric layer 20 can refer to the description in the aforementioned first embodiment.

[0047] The thickness of the support layer 10 in step S1 is 250 to 500 microns, and the thickness of the piezoelectric layer 20 is 150 to 250 microns. 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 support main surface 11 and the bonding main surface 21 is less than or equal to 0.5 nm. Before step S3, for example, the surface of the piezoelectric layer 20 is reduced so that the conductivity of the bonding main surface 21 reaches 1×10 -12 ~1×10 -9 S / m (Siemens / cm), and there are a large number of oxygen vacancies.

[0048] Step S2 can refer to Figure 8 As shown in step (a), the ion gun 300 is used to emit Ar (argon) ions to activate the support main surface 11 and the bonding main surface 21. After step S2, refer to Figure 8 Step S3 is performed as shown in step (b) to obtain the bonded substrate 101. Since the surface of the piezoelectric layer 20 has a large number of oxygen vacancies, the active atoms or ions on the surface of the support layer 10 can easily diffuse into the piezoelectric layer 20 to form a diffusion region 22, and finally form Figure 8 The composite substrate 100 shown in step (c).

[0049] In some specific embodiments, constituent elements of the polycrystalline compound of the support layer 10 include characteristic elements different from constituent elements of the piezoelectric material of the piezoelectric layer 20 , and the diffusion region 22 includes at least one characteristic element.

[0050] In some embodiments, the method for preparing the composite substrate further includes step S4, annealing the bonded substrate 101 after the bonding process. The temperature of the annealing process is, for example, 100 to 300° C. The annealing process can accelerate the formation of the diffusion region 22 and promote the diffusion region 22 to reach a suitable diffusion depth (thickness), so that the thickness of the diffusion region 22 is controllable, which is convenient for mass production to ensure the consistency of the diffusion depth. Specifically, step S4 adopts a low-temperature oxygen-free annealing process, and the oxygen-free environment can prevent the resistance of the piezoelectric layer 20 from changing during the annealing process.

[0051] In some embodiments, reference Figure 8 In step (d) of the bonding process, the method for preparing the composite substrate further includes step S5: thinning the piezoelectric layer 20 after the bonding process S3, so that the thickness of the piezoelectric layer 20 reaches less than 5 microns (less than or equal to 5 microns). Wherein, when step S3 is followed by step S4, step S5 is performed after step S4. Thinning and polishing the piezoelectric layer 20 in step S5 can achieve thin filmization of the piezoelectric layer 20, so as to facilitate the preparation of the TF-SAW device.

[0052] Figures 2 to 7 The observation results of a composite substrate 100 prepared by the preparation method provided in this embodiment are shown in a specific embodiment. In this specific embodiment, the piezoelectric material of the piezoelectric layer 20 is lithium tantalate (chemical formula: LiTaO3, referred to as LT), and the polycrystalline compound of the support layer 10 is magnesium aluminum spinel (Spinel). Figure 2 The dotted line frame captures the area on both sides of the bonding interface between the support layer 10 and the piezoelectric layer 20. Figure 3 Middle Pair Figure 2 Further magnification of the dotted box area shows a diffusion region 22 ( Figure 3 The black solid line frame area), Figure 3 The upper right corner (scale is 1 / 5 nanometer) shows the atomic state of the diffusion zone 22 under high-magnification STEM observation. It can be seen that the atoms are clearly evenly arranged, so it can be determined that the diffusion zone 22 is a quasi-crystalline layer, rather than an amorphous state. This quasi-crystalline layer structure makes the heat conduction between the diffusion zone 22 and the non-diffusion zone (i.e., the area of ​​the piezoelectric layer 20 other than the diffusion zone) smoother, which is beneficial to the improvement of TCF. It can be understood that the main component of the diffusion zone 22 is still the piezoelectric material of the piezoelectric layer 20, but some elements diffuse from the support layer 10 into the piezoelectric layer 20 to form the diffusion zone 22. According to Figure 3The direction indicated by the black arrow (i.e., the direction from LT to Spniel) is the measurement direction for element analysis on both sides of the interface. Figure 4 , Ta (tantalum) atoms do not diffuse, and there is a clear boundary between LT and Spinel. Figure 5 It is impossible to determine the diffusion of O (oxygen) atoms. Figure 6 , a relatively low concentration of aluminum diffuses to the LT, with a depth of 1 to 1000 nm, and the mass percentage of aluminum in the diffusion zone 22 is measured to be 0.5 to 10 wt%. Figure 7 , a medium concentration of magnesium element diffuses to LT, the depth is 1-1000nm, and the mass percentage of magnesium element in the diffusion zone 22 is measured to be 1-10wt%. It can be seen that the composite substrate preparation method provided by the second embodiment of the present invention can prepare the composite substrate 100 provided by the first embodiment.

[0053] Table 1 shows the diffusion depth and mass percentage of magnesium and aluminum elements in the diffusion zone 22 of the composite substrate 100 (the polycrystalline compound of the support layer 10 is magnesium-aluminum spinel) in some embodiments. According to Table 1, when the diffusion depth is less than or equal to 40nm, the greater the diffusion depth, the greater the mass percentage of magnesium and aluminum elements. When the diffusion depth is greater than 40nm, as the diffusion depth gradually increases, the mass percentage of magnesium and aluminum elements gradually decreases, and a diffusion zone 22 with a maximum thickness of 1000nm can be formed.

[0054] Table 1:

[0055] Diffusion Depth 20nm 40nm 100nm 300nm 500nm 1000nm Mg element mass percentage ≤7.1％ ≤7.5％ ≤5.9％ ≤4.3％ ≤2.5％ ≤1.0％ AL element mass percentage ≤4.2％ ≤4.4％ ≤2.6％ ≤1.1％ ≤0.8％ ≤0.5％

[0056] The following describes the effect of the composite substrate 100 obtained by the composite substrate preparation method through experiments one to four. In experiment one, it is ensured that only a few atoms or ions on the surface of the piezoelectric layer 20 and the support layer 10 are activated and bonded, and an IDT electrode is prepared on the basis of the obtained composite substrate 100, and used for the electrical test of the filter. In experiment two, it is ensured that only some atoms or ions on the surface of the piezoelectric layer 20 and the support layer 10 are activated and bonded, and an IDT electrode is prepared on the basis of the obtained composite substrate 100, and used for the electrical test of the filter. In experiment three, it is ensured that most atoms or ions on the surface of the piezoelectric layer 20 and the support layer 10 are activated and bonded, and an IDT electrode is prepared on the basis of the obtained composite substrate 100, and used for the electrical test of the filter. In experiment four, it is ensured that most atoms or ions on the surface of the piezoelectric layer 20 and the support layer 10 are activated and bonded, and an IDT electrode is prepared on the basis of the obtained composite substrate 100, and used for the electrical test of the filter.

[0057] The results of the electrical test of Experiments 1 to 4 are shown in Table 2.

[0058] Table 2:

[0059] Experiment 1 Experiment 2 Experiment 3 Experiment 4 Diffusion zone magnesium content <1.0wt% 5.7wt% 7.1wt% 7.5wt% Aluminum content in diffusion zone <0.5wt% 2.4wt% 4.2wt% 4.4wt% Diffusion layer thickness 0～5 6~10nm 15~25nm 30~40nm Yield 92.17％ 93.43％ 96.21％ 95.20％ Frequency Difference 2.15 2.07 2.2 2.09 Insertion loss difference 0.39 0.38 0.43 0.36 TCF(ppm / K) -13.9 -13.7 -13.2 -12.5

[0060] The frequency difference in Table 2 is the difference between the filter receiving end frequency and the designed standard frequency, and the insertion loss difference indicates the difference in insertion loss between the receiving end and the transmitting end. According to the data of Experiments 1 to 4, the change in the thickness of the diffusion zone 22 (that is, the diffusion depth of magnesium and aluminum elements) has little effect on the electrical parameters, and can meet the requirements of traditional TC-SAW and TF-SAW, and the thickness of the diffusion zone 22 formed increases the TCF significantly optimized. After the metal ions diffuse into the piezoelectric layer 20, the oxygen vacancies on the surface of the piezoelectric layer 20 are supplemented, and the thermal conductivity and electrical conductivity of the device are significantly changed, resulting in a certain improvement in the characteristics of the filter device in TCF. Increasing the thickness of the diffusion zone 22 is beneficial to reducing the interference of temperature on the filter device and maintaining stable performance. Therefore, the composite substrate 100 prepared by the above-mentioned preparation method can not only introduce temperature compensation, but also thin the piezoelectric layer 20, and has the advantages of both TC-SAW and TF-SAW.

[0061] [Third embodiment]

[0062] The third embodiment of the present invention provides an electronic device 200, including the composite substrate 100 of any one of the first embodiments, or the composite substrate 100 prepared by the composite substrate preparation method of the second embodiment. The specific description of the composite substrate 100 can refer to the description of the first and second embodiments, and will not be repeated here. The electronic device 200, for example, also includes an electrode 30 disposed on the side of the piezoelectric layer 20 away from the support layer 10, referring to Fig. 9 The electrode 30 is, for example, an IDT electrode, and the electronic device 200 is, for example, a SAW device.

[0063] In some embodiments, the electronic device 200 is subjected to an electrical test, and the temperature drift coefficient of the electronic device 200 is -10 to -40 ppm / K.

[0064] The electronic device 200 provided in the third embodiment of the present invention includes the composite substrate 100 of the first and second embodiments, and has the same beneficial effects as the first and second embodiments, which will not be described in detail herein.

[0065] Reference Fig.10The third embodiment of the present 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 200 (including a composite substrate 100), 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 200 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 200 on the wiring substrate 700.

[0066] The module 1000 provided in this embodiment includes the electronic device 200 and has the same beneficial effects as the electronic device 200, which will not be described in detail herein.

[0067] 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 composite substrate, characterized in that: include: a support layer, the support layer comprising a polycrystalline compound; A piezoelectric layer, wherein the piezoelectric layer is formed on the support layer, and the piezoelectric layer has a diffusion region extending from a lower surface thereof close to the support layer toward a direction gradually away from the support layer; Wherein, the piezoelectric layer includes a piezoelectric material, the constituent elements of the polycrystalline compound include characteristic elements different from the constituent elements of the piezoelectric material, the diffusion zone is based on the piezoelectric material and includes at least one of the characteristic elements; the piezoelectric material has at least one element different from the constituent elements of the polycrystalline compound, and the element is only located in the piezoelectric layer.

2. The composite substrate according to claim 1, characterized in that The polycrystalline compound is selected from any one of polycrystalline spinel compounds, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, and aluminum oxynitride.

3. The composite substrate according to claim 2, characterized in that The polycrystalline compound is a polycrystalline spinel compound including a first metal element, a second metal element and an oxygen element, and the diffusion region includes the first metal element and the second metal element.

4. The composite substrate according to claim 3, characterized in that The mass percentage of the first metal element in the diffusion zone is 1-20 wt %, and the mass percentage of the second metal element is 1-20 wt %.

5. The composite substrate according to claim 4, characterized in that The difference in mass percentage between the first metal element and the second metal element in the diffusion region is 1-5wt%, and the metal activity of the first metal element is higher than that of the second metal element.

6. The composite substrate according to claim 1, wherein: The diffusion region is a quasi-crystalline layer formed by supplementing oxygen vacancies in the piezoelectric layer with at least one of the characteristic elements.

7. A method for preparing a composite substrate, characterized in that: include: providing a support layer, the support layer comprising a polycrystalline compound; forming a piezoelectric layer on the support layer to obtain the composite substrate; The piezoelectric layer includes a piezoelectric material, and the constituent elements of the polycrystalline compound include a characteristic element different from the constituent elements of the piezoelectric material; Before forming the piezoelectric layer, the surfaces of the support layer and the piezoelectric material are activated so that at least one of the characteristic elements can diffuse unidirectionally from the support layer into the piezoelectric material, so as to form a diffusion zone in the piezoelectric layer extending from its lower surface close to the support layer toward gradually away from the support layer, wherein the diffusion zone is based on the piezoelectric material and includes at least one of the characteristic elements, and the piezoelectric material has at least one element different from the constituent elements of the polycrystalline compound, and the element is only located in the piezoelectric layer.

8. The method for preparing a composite substrate according to claim 7, characterized in that: Also includes: Before forming the piezoelectric layer, the lower surface of the piezoelectric material is subjected to a reduction treatment so that the conductivity of the lower surface of the piezoelectric layer reaches 1×10 -12 ~1×10 -9 S / m.

9. An electronic device, characterized in that: The invention comprises a composite substrate as claimed in any one of claims 1 to 6, or comprises a composite substrate prepared by the preparation method as claimed in any one of claims 7 to 8.

10. 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 as claimed in claim 9.

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