Substrate structure, filter and duplexer

Abstract

A substrate structure and its manufacturing method, a filter, and a duplexer, which relate to the field of filter technology. The substrate structure includes a support substrate and a piezoelectric layer located on the support substrate, where the material of the support substrate is a polycrystalline material, and the porosity of the support substrate is less than 0.0045% or more than 0.6%. The substrate structure can effectively improve the generation of interference noise and improve the operating performance of the device.

Description

[Technical field]

[0001] The present disclosure relates to the technical field of electronic devices, and more particularly to a substrate structure and its manufacturing method, a filter, and a duplexer. [Background technology]

[0002] Surface acoustic wave filters are widely used in various communication devices. In order to adapt to various more severe external environments in future communication applications, there is a strong demand for improving the operational stability of surface acoustic wave filters. Conventional surface acoustic wave filters have low Q values ​​(<1000), low operating frequencies, and frequency drift with changes in operating temperature. These make it difficult to meet the filter requirements of high-frequency terminals in the 5G era, where frequency bands are becoming increasingly crowded. Therefore, conventional surface acoustic wave filters must be developed into temperature-compensated filters that have high frequencies and stable temperature characteristics.

[0003] The key point to realize the transformation of a conventional surface acoustic wave filter into a temperature-compensated filter is to add a support layer structure to the simple piezoelectric layer structure. After adding the support layer structure, on the one hand, the thickness of the piezoelectric layer can be effectively reduced, and the Q value of the device can be increased; on the other hand, the support layer structure has a better thermal expansion coefficient, so that the frequency drift phenomenon caused by the temperature of the device can be effectively improved. However, the support layer structure of the conventional temperature-compensated filter device is generally a high-density, high-sound-speed material, so it cannot improve the temperature drift characteristics of the device and avoid the generation of a large amount of interference noise. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a substrate structure and a manufacturing method thereof, a filter, and a duplexer that can effectively reduce the occurrence of interference noise and improve the operating performance of a device. [Means for solving the problem]

[0005] One aspect of the present disclosure provides a substrate structure, the substrate structure including a support substrate and a piezoelectric substrate located on the support substrate, wherein the material of the support substrate is a polycrystalline material, and the porosity of the support substrate is less than 0.0045% or greater than 0.6%, and the number of grain boundary layers of the support substrate is three or more.

[0006] In this substrate structure, the pores and grain boundaries in the polycrystalline material can both absorb and attenuate the scattering of acoustic waves, and can be consumed in the process of transmitting the surface acoustic waves into the supporting substrate or to the lower surface, thereby significantly reducing the acoustic waves reflected on the upper surface, effectively improving the generation of interference noise, and improving the operating performance of the device.

[0007] Another aspect of the present disclosure provides a method for manufacturing a substrate structure, the method including: providing a support substrate, the material of the support substrate being a polycrystalline material, and the porosity of the support substrate being less than 0.0045% or greater than 0.6%, and bonding a piezoelectric substrate onto the support substrate to obtain a substrate structure.

[0008] Another aspect of the present invention provides a compensated substrate including a support substrate and a piezoelectric substrate located on the support substrate, wherein the material of the support substrate is a polycrystalline material, and the number of crystal grains per unit area of ​​the support substrate is 6 or more, the unit area is 100 μm×100 μm, and the number of crystal grain boundary layers is 3 or more.

[0009] The compensated substrate provided by the present disclosure can effectively reduce the thickness of the piezoelectric substrate by placing a support substrate under the piezoelectric substrate, increase the Q value of the filter, and realize the technical improvement from the conventional surface acoustic wave filter to a temperature compensated SAW filter with high frequency and stable temperature characteristics. The grain boundaries of the polycrystalline material play the role of absorption and attenuation for scattering of sound waves, and the surface acoustic wave is transmitted to the inside or the lower surface of the support substrate, and the sound waves are consumed by the grain boundaries and pores, and the sound waves reflected on the surface are significantly reduced, thereby playing a role in reducing noise, so that the noise can be effectively reduced by setting the material of the support substrate to a polycrystalline material. By limiting the number of crystal grains per unit area, it is possible to control the size of the crystal grains in the polycrystalline material. By setting the number of crystal grains per unit area, on the one hand, it is possible to avoid the problem that the crystal grain size is too large, which causes few crystal grain boundaries and is prone to noise in the manufactured filter device, and on the other hand, it is possible to prevent the problem that the crystal grain size is too small, which causes an increase in pores and a decrease in the Q value of the device.

[0010] In another aspect of the present disclosure, a method for manufacturing a compensated substrate provided by the present disclosure includes the steps of: providing a support substrate, the material of the support substrate being a polycrystalline material, the number of crystal grains per unit area of ​​the support substrate being 6 or more, and the unit area of ​​the support substrate being 100 μm×100 μm; and bonding a piezoelectric substrate onto the support substrate to obtain a compensated substrate. The method for manufacturing a compensated substrate provided by the present disclosure can be applied to a temperature-compensated filter by bonding a piezoelectric substrate onto the support substrate to obtain a compensated substrate, which can effectively improve the frequency drift caused by the temperature of the support substrate and increase the Q value of the device.

[0011] Another aspect of the present disclosure provides a filter, the filter including a substrate structure and an electrode disposed on the substrate structure.

[0012] Another aspect of the present disclosure provides a duplexer, the duplexer including a transmit filter and a receive filter, where the transmit filter and / or the receive filter employ the above filter. Effect of the Invention

[0013] Compared with the prior art, the filter provided by the present disclosure effectively improves the performance of the filter and greatly reduces the noise interference. [Brief description of the drawings]

[0014] [Figure 1] 1 is a structural schematic diagram of a substrate structure provided according to some embodiments of the present disclosure. [Diagram 2] 1 is a structural schematic diagram of a support substrate provided according to some embodiments of the present disclosure. [Diagram 3] FIG. 2 is a structural schematic diagram of a support substrate provided according to some embodiments of the present disclosure. [Figure 4] 3 is a structural schematic diagram of a support substrate provided according to some embodiments of the present disclosure. [Diagram 5] 4 is a structural schematic diagram of a support substrate provided according to some embodiments of the present disclosure. [Figure 6] FIG. 5 is a structural schematic diagram of a support substrate provided according to some embodiments of the present disclosure. [Figure 7] 6 is a structural schematic diagram of a support substrate provided according to some embodiments of the present disclosure. [Figure 8] FIG. 2 is a schematic diagram of a noise measurement scheme provided by some embodiments of the present disclosure. [Figure 9] 1 is a flowchart 1 of a method for manufacturing a substrate structure provided according to some embodiments of the present disclosure. [Figure 10] 2 is a flow chart 2 of a method for manufacturing a substrate structure provided according to some embodiments of the present disclosure. [Figure 11] 1 is a structural schematic diagram of a filter provided according to some embodiments of the present disclosure. [Figure 12] 1 is a structural schematic diagram of a substrate structure provided according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Conventional temperature compensation filter devices generally add a support structure to the structure of the piezoelectric layer, but the conventional support structure generally selects materials with high density and high sound speed, which may cause a large amount of noise during the use of the device. To solve the above problem, the present application provides a new substrate structure, which has a special polycrystalline structure, and the filter using the substrate structure can fulfill the basic function of the filter and improve the noise.

[0016] Hereinafter, the present application will discuss and explain in detail the specific structure of the new substrate structure. Example 1

[0017] 1, the substrate structure provided in this embodiment includes a support substrate 10 and a piezoelectric substrate 20 located on the support substrate 10, where the material of the support substrate 10 is a polycrystalline material, and the porosity of the support substrate 10 is less than 0.0045% or greater than 0.6%. This substrate structure can effectively improve the generation of interference noise and improve the operating performance of the device.

[0018] Here, the material of the support substrate 10 is a polycrystalline material, and for example, the polycrystalline material may be any one of polycrystalline spinel, polycrystalline sapphire, polycrystalline silicon, polycrystalline quartz, and polycrystalline aluminum nitride.

[0019] The piezoelectric substrate 20 can be selected from LT (lithium tantalate) and LN (lithium niobate) piezoelectric substrates.

[0020] In addition, the main cause of sound attenuation is the absorption of sound waves by the medium. Therefore, the present application selects a polycrystalline material with a certain porosity as the material for the support substrate 10, so that factors such as the crystal grain boundaries of the polycrystalline material and the unevenness of the microdomains (i.e., pores), as shown in Figure 1, can effectively reduce the energy of longitudinal wave transmission, and further suppress and attenuate noise.

[0021] In this embodiment, the porosity of the support substrate 10 is less than 0.0045% or more than 0.6%. Exemplarily, when the porosity of the support substrate 10 is less than 0.0045%, the specific porosity of the support substrate 10 may be 0.0044%, 0.0043%, 0.0040%, 0.0035%, 0.0030%, 0.0020%, 0.0010%, etc., and the present application does not recite them one by one.

[0022] When the porosity of the support substrate 10 is greater than 0.6%, the specific porosity of the support substrate 10 may be 0.65%, 0.7%, 0.8%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, etc. Of course, the specific values ​​of the porosity of the support substrate 10 are merely examples and are not limitations on the specific porosity of the support substrate 10, and those skilled in the art may select an appropriate porosity as needed, as long as the porosity is less than 0.0045% or greater than 0.6%.

[0023] In this embodiment, when the porosity of the support substrate 10 is greater than 0.6%, the porosity of the support substrate 10 can be selectively selected to be greater than 0.65%. In this way, the generation of noise can be more effectively suppressed and attenuated.

[0024] In order to further suppress and attenuate interference noise and improve the operation performance of the device, optionally, the porosity of the support substrate 10 is greater than 0.65% and less than 1.5%. For example, the porosity of the support substrate 10 may be 0.7%, 0.9%, 1.0%, 1.3%, or 1.4%, etc.

[0025] In this embodiment, the number of grain boundary layers of the support substrate 10 is optionally three or more.

[0026] First, the material of the support substrate 10 is a polycrystalline material, and therefore, as shown in Figures 2 and 3, the support substrate 10 has a plurality of crystal grains. Here, the crystal grain boundary is the boundary between two adjacent crystal grain layers, and includes three crystal grain boundary layers in Figure 3 corresponding to Figure 3 (the three crystal grain boundary layers are indicated by black lines in Figure 3).

[0027] Next, grain boundaries in the medium and unevenness in microdomains (e.g., pores) can both cause sound waves to scatter at the interfaces between these regions, resulting in energy attenuation (scattering attenuation). Since there are more grain boundary layers in the support substrate 10 than there are pores in the support substrate 10, the grain boundary layers can provide good suppression and attenuation effects on sound waves propagating downward from the surface of the electrode 30.

[0028] The multiple crystal grain boundaries of the support substrate 10 absorb and attenuate the scattering of sound waves, and as the sound waves transmitted to the inside or underside of the support substrate 10 of the surface acoustic wave are consumed by the crystal grain boundaries and pores, the sound waves reflected on the surface are significantly reduced, as shown in FIG. 1, thereby reducing noise.

[0029] 4 to 7, which are drawings showing the cases where the number of grain boundary layers in the support substrate 10 is at least 0, 1, 2, and 3, respectively. The positions indicated by the white arrows are the positions with the fewest grain boundary layers in the side cross sections of the four types of samples, and the positions where the number of grain boundary layers is reduced correspond to the positions where the size of the crystal grains is large and the number of crystal grains per unit area is small, and the areas near the white arrows are basically the positions with the fewest number of crystal grains per unit area, which are 3, 4, 5, and 7 grains, respectively. The characteristics of the filters manufactured using the four types of support substrate 10 are shown in the table below.

[0030] [Table 1] The noise measurement method in the above table refers to FIG. 8. 21 positions are selected at the fixed coordinate points of each sample to manufacture a filter and test its characteristics. If no noise occurs at any of the 21 test points, the noise yield is expressed as 100% (sample 4 in the above table). If noise occurs at one position, the noise yield can be obtained based on the ratio as 95%.

[0031] As can be seen from the above table, the four different samples have obvious differences in noise, but the remaining characteristics are almost similar. Thus, it can be seen that the number of grain boundary layers definitely affects noise, and as can be seen from the analysis of the table data, when the number of grain boundary layers is ≧3, the generation of noise can be better suppressed.

[0032] In addition, controlling the number of grain boundaries means controlling the grain size of the polycrystalline substrate. If the size is too large, there will be few grain boundaries, and the manufactured filter device will be prone to noise. If the size of the grains is too small, there will be many grain boundaries, but the pores will also increase, which may improve noise and reduce the Q value of the device. Therefore, the number of grain boundary layers cannot be increased infinitely, and therefore, in this embodiment, the number of grain boundary layers is selectively 40 layers or less. Specifically, the specific number of grain boundary layers may be selected by those skilled in the art according to the actual situation, and the present application does not particularly limit it.

[0033] Optionally, the support substrate 10 provided by the present application includes a plurality of crystal grains, and the average grain size of the crystal grains is between 2 μm and 60 μm. Exemplarily, the average grain size of the crystal grains may be 2 μm, 10 μm, 20 μm, 30 μm, 50 μm, or 60 μm, etc.

[0034] In this embodiment, the grain size of the crystal grains can be between 1 μm and 80 μm. For example, the grain size of the crystal grains may be 1 μm, 5 μm, 20 μm, 40 μm, 50 μm, or 80 μm.

[0035] The average grain size of the crystal grains is related to the thickness T of the support substrate, and the number of grain boundary layers in the support substrate 10 of the present application must be three or more. Therefore, the average grain size of the crystal grains should be one-third or less of the thickness T of the support substrate.

[0036] In this embodiment, the thickness of the piezoelectric substrate is optionally between 0.1 μm and 10 μm, and preferably between 0.5 μm and 5 μm.

[0037] Furthermore, the material of the support substrate 10 is a polycrystalline material, and the number of crystal grains per unit area of ​​the support substrate 10 is 6 or more, and the number of crystal grains per unit area of ​​the support substrate 10 is 200 or less, and the unit area is 100 μm × 100 μm.

[0038] For example, the number of crystal grains per unit area of ​​the support substrate 10 may be 10 to 100. If the number of crystal grains is too large, the hardness of the support substrate 10 increases, which is disadvantageous in thinning and polishing the support substrate 10, and increases material loss and processing time, while if the number of crystal grains is too small, the processing difficulty of the support substrate 10 can be reduced, but the material strength of the support substrate 10 decreases. For this reason, the number of crystal grains per unit area of ​​the support substrate 10 is preferably between 10 and 30 grains.

[0039] In short, the substrate structure provided by the present application includes a support substrate 10 and a piezoelectric substrate 20 located on the support substrate 10, where the material of the support substrate 10 is a polycrystalline material, and the porosity of the support substrate 10 is less than 0.0045% or greater than 0.6%. The present application selects a polycrystalline material as the material of the support substrate 10, and sets the porosity of the support substrate 10 to less than 0.0045% or greater than 0.6%, so that the pores and grain boundaries in the polycrystalline material can both absorb and attenuate the scattering of acoustic waves, and can be consumed in the process of transmitting the surface acoustic wave to the inside or lower surface of the support substrate 10, thereby significantly reducing the acoustic wave reflected to the upper surface, thereby reducing noise and improving the operating performance of the device. Example 2

[0040] A polycrystalline spinel support substrate 10 is selected, characterized in that the porosity of the support substrate 10 is between 1% and 1.5%, the number of grain boundary layers is 40 layers or more and the number of grain boundaries is >10 layers, and the average grain size is about 6 μm.

[0041] The support substrate 10 and the piezoelectric substrate 20 were bonded together, and then thinned and polished to obtain a finished substrate structure with a piezoelectric substrate 20 having a thickness of 5 μm and a support substrate having a thickness T of 250 μm. An electrode 30 was formed on the substrate structure to obtain a filter, and the characteristics of the filter were verified. The characteristics of a filter manufactured using a support substrate 10 with a porosity between 0.0045% and 0.6% were used as a reference standard, and the obtained parameters are shown in the table below.

[0042] [Table 2]

[0043] As can be seen from analyzing the above table, when the porosity is between 0.0045% and 6%, there is still a large noise interference, but when the porosity of the support substrate 10 is selected between 1% and 1.5%, the noise can be significantly improved.

[0044] In addition, when the porosity of the support substrate 10 is between 1% and 1.5%, the material strength is inevitably reduced due to the high porosity. In response to such a case, the average grain size of the support substrate 10 can be appropriately reduced, and for example, a support substrate 10 with an average grain size ≦4 μm may be selected, and thus the grain size D of most of the grains is between 1 μm and 2 μm. Thus, the smaller the grain size D of the selected grains, the better the mechanical performance of the material. Macroscopically, there are increases in yield and tensile strength, increases in surface hardness, and increases in fatigue life. The specific principle is that the finer the grains are, the more grains there are in a unit volume, and the more grains involved in deformation, the more uniform the deformation, and the greater the plastic deformation that occurs before fracture. Strength and plasticity increase simultaneously, and the power consumed by the material before fracture is also large, and therefore its toughness is also high. Example 3

[0045] A polycrystalline spinel support substrate 10 is selected, characterized in that the porosity of the support substrate 10 is between 0.65% and 1%, the number of grain boundary layers is 40 layers or more and the number of grain boundaries is >3 layers, and the average grain size is about 45 μm.

[0046] The support substrate 10 and the piezoelectric substrate 20 were bonded together, and then thinned and polished to obtain a finished substrate structure with a piezoelectric substrate 20 having a thickness of 5 μm and a support substrate having a thickness T of 250 μm. An electrode 30 was formed on the substrate structure to obtain a filter, and the characteristics of the filter were verified. The characteristics of a filter manufactured using a support substrate 10 with a porosity between 0.0045% and 0.6% were used as a reference standard, and the obtained parameters are shown in the table below.

[0047] [Table 3]

[0048] As can be seen from analyzing the above table, there is still a large noise interference when the porosity is between 0.0045% and 0.6%, and after the porosity of the support substrate 10 is selected to be 0.6% or more, it can significantly improve the noise. Example 4

[0049] A polycrystalline spinel support substrate 10 is selected, characterized in that the support substrate 10 has a porosity of 0.0045% or less, the number of grain boundary layers is 40 layers or more, and the average grain size is about 10 μm.

[0050] The support substrate 10 and the piezoelectric substrate 20 were bonded together, and then thinned and polished to obtain a finished substrate structure with a piezoelectric substrate 20 having a thickness of 5 μm and a support substrate having a thickness T of 250 μm. An electrode 30 was formed on the substrate structure to obtain a filter, and the characteristics of the filter were verified. The characteristics of a filter manufactured using a support substrate 10 with a porosity between 0.0045% and 0.6% were used as a reference standard, and the obtained parameters are shown in the table below.

[0051] [Table 4]

[0052] As can be seen from analyzing the above table, when the porosity is between 0.0045% and 0.6%, there is still a large noise interference, but when the porosity of the support substrate 10 is selected to be 0.0045 or less, the noise can be significantly improved.

[0053] According to the above three embodiments, when the supporting substrate 10 adopts a polycrystalline material and the porosity of the polycrystalline material is selected to be less than 0.0045% or greater than 0.6%, the noise can be significantly improved, thereby improving the operating performance of the device.

[0054] Referring to FIG. 9 , another aspect of the present disclosure provides a method for manufacturing a substrate structure, the method for manufacturing the substrate structure includes: A step S100 of providing a support substrate 10, the material of the support substrate 10 being a polycrystalline material, and the porosity of the support substrate 10 being less than 0.0045% or more than 0.6%; and step S200 of bonding the piezoelectric substrate 20 onto the supporting substrate 10 to obtain a substrate structure.

[0055] It should be noted that the material of the supporting substrate 10 is a polycrystalline material, and for the specific type of the polycrystalline material and the specific selection of the porosity of the polycrystalline material, those skilled in the art may refer to the above description, and the present application will not repeat the description.

[0056] Similarly, reference may be made to the above description for specific materials of the piezoelectric substrate 20. The bonding process is well known to those skilled in the art, so the present application will not repeat the description.

[0057] Also referring to FIG. 10, optionally, the above step S200 of bonding the piezoelectric substrate 20 onto the supporting substrate 10 to obtain a substrate structure includes steps S210 to S230.

[0058] In S210, the piezoelectric substrate 20 is bonded onto the support substrate 10.

[0059] Prior to bonding, the bonding surface of the piezoelectric substrate 20 may be polished to a roughness of 0.3 nm or less, and similarly, the bonding surface of the support substrate 10 may be polished prior to bonding to a roughness of 0.8 nm or less.

[0060] The bonding may be performed in a room temperature, high vacuum environment by an ion activation method.

[0061] In S220, the surface of the piezoelectric substrate 20 that faces away from the support substrate 10 is thinned and polished to a thickness of less than 10 μm.

[0062] In S230, the surface of the support substrate 10 that faces away from the piezoelectric substrate 20 is thinned and polished to reduce the thickness T of the support substrate 10 to less than 250 μm, thereby obtaining a substrate structure.

[0063] Referring to FIG. 11, another aspect of the present disclosure provides a filter, which includes a substrate structure and an electrode 30 disposed on the substrate structure.

[0064] The electrode 30 is an electrode finger 30. The specific structure of the substrate structure and its beneficial effects have been described in detail above, so they will not be described here.

[0065] Another aspect of the present disclosure provides a duplexer, which includes a transmit filter and a receive filter, and the transmit filter and / or the receive filter adopt the above filter. The specific structure and effect of the filter have both been described in detail above, and therefore will not be described here.

[0066] 12, the present application further provides a compensated substrate for use in a filter device, the compensated substrate includes a support substrate 10 and a piezoelectric substrate 20 located on the support substrate 10, the material of the support substrate 10 is a polycrystalline material, and the number of crystal grains per unit area of ​​the support substrate 10 is 6 or more, and the unit area is 100 μm×100 μm. In this embodiment, the number of crystal grains per unit area of ​​the support substrate 10 is 6 or more, and the specific number of crystal grains is not limited, and may be set by those skilled in the art as needed. The compensated substrate described in this embodiment can effectively reduce the thickness of the piezoelectric substrate 20 by placing the support substrate 10 under the piezoelectric substrate 20, and can increase the Q value of the filter, realizing the technical improvement from the conventional surface acoustic wave filter to a temperature compensated SAW filter with high frequency and stable temperature characteristics. The grain boundaries of polycrystalline materials play a role in absorbing and attenuating the scattering of sound waves, and the surface acoustic waves are transmitted to the inside or underside of the support substrate, and the sound waves are consumed by the grain boundaries and pores, and the sound waves reflected on the surface are significantly reduced, thereby playing a role in reducing noise. Therefore, by setting the material of the support substrate 10 to a polycrystalline material, noise can be effectively reduced. By limiting the number of crystal grains per unit area, it is possible to control the size of the crystal grains in the polycrystalline material. By setting the number of crystal grains per unit area, on the one hand, it is possible to avoid the crystal grain size being too large, which causes few crystal grain boundaries and makes the manufactured filter device prone to noise, and on the other hand, it is possible to prevent the crystal grain size being too small, which causes the problem of increased pores and reduced Q value of the device.

[0067] Alternatively, the number of crystal grains per unit area of ​​the support substrate 10 is 200 or less. In this embodiment, the number of crystal grains in the support substrate 10 per unit area of ​​100 μm×100 μm must be 200 or less and 6 or more. More preferably, the number of crystal grains in the support substrate 10 per unit area of ​​100 μm×100 μm is 10 to 100. Illustratively, the number of crystal grains in the support substrate 10 per unit area of ​​100 μm×100 μm may be 10, 30, or 100.

[0068] By controlling the number of crystal grains within the range of 10 to 100 grains, noise can be improved while the strength of the material can be ensured within an appropriate range, so that the difficulty of processing the material is not increased. If the number of crystal grains is too large, the hardness of the material of the support substrate 10 increases, which is disadvantageous in performing thinning and polishing operations on the support substrate 10, and increases material loss and processing time. Therefore, by controlling the number of crystal grains, not only can noise be improved, but the difficulty of production processing can also be effectively reduced. The specific number of crystal grains is not limited here, and can be set by those skilled in the art according to actual needs.

[0069] Optionally, the number of grain boundary layers is 3 or more, and / or the number of grain boundary layers is 40 or less. By limiting the number of grain boundary layers, the arrangement of grains in the cross section of the support substrate can be controlled, and if the number of grain boundary layers is less than 3 layers, the grain boundaries are too few, and the sound waves cannot be effectively absorbed and consumed, which is disadvantageous to noise reduction. If the number of grain boundary layers is too large, the size of the grains becomes too small and the porosity increases, which may improve noise and reduce the Q value of the device.

[0070] Optionally, the material of the support substrate 10 is any one of polycrystalline spinel, polycrystalline sapphire, polycrystalline silicon, polycrystalline quartz, and polycrystalline aluminum nitride.

[0071] Optionally, the piezoelectric substrate 20 is made of a piezoelectric material and has a piezoelectric effect. The piezoelectric material is lithium tantalate in this embodiment 1, but in other embodiments of the present invention, the piezoelectric material may be lithium niobate. In this embodiment, the thickness of the piezoelectric substrate is 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

[0072] The manufacturing method of the compensated substrate provided by this embodiment includes the steps of providing a support substrate 10, where the material of the support substrate 10 is a polycrystalline material, the number of crystal grains per unit area of ​​the support substrate 10 is 6 or more, and the unit area of ​​the support substrate 10 is 100 μm × 100 μm, and bonding a piezoelectric substrate 20 onto the support substrate 10 to obtain a compensated substrate.

[0073] Here, the step of bonding the piezoelectric substrate 20 onto the support substrate 10 to obtain a compensated substrate includes the steps of bonding the piezoelectric substrate 20 onto the support substrate 10, successively thinning and polishing the surface of the piezoelectric substrate 20 away from the support substrate to make the thickness of the piezoelectric substrate 20 less than 10 μm, and successively thinning and polishing the surface of the support substrate 10 away from the piezoelectric substrate 20 to make the thickness of the support substrate 10 less than 400 μm to obtain a compensated substrate. Here, the compensated substrate obtained by making the thickness of the support substrate 10 between 150 and 250 μm has excellent performance, and may be, for example, 180 to 220 μm. The compensated substrate obtained by bonding the piezoelectric substrate 20 onto the support substrate 10 can be applied to a temperature compensated filter, and can effectively improve the frequency drift due to the temperature of the support substrate 10 and increase the Q value of the device.

[0074] Specifically, LT (lithium tantalate) is selected as the piezoelectric substrate 20, one surface of the piezoelectric substrate 20 is polished to a surface roughness of 0.3 nm or less, and this processed surface is used as the bonding surface of the piezoelectric substrate 20, and polycrystalline spinel is selected as the support substrate 10, one surface of the support substrate 10 is polished to a surface roughness of 0.8 nm or less, and this processed surface is used as the bonding surface of the support substrate 10. The bonding surfaces of the piezoelectric substrate 20 and the support substrate 10 are bonded in a room temperature high vacuum environment by an ion activation method. Finally, a compensation type substrate with a LT thickness of 5 μm and a spinel thickness of 240 μm is obtained as the finished product.

[0075] To further illustrate the superior performance of the filters provided by the embodiments of the present application, tests are performed using the filters provided by the present application.

[0076] Test Example 1: In a specific test, the average grain size of the support substrate 10 was set to about 6 μm, the number of grain boundary layers was set to >10, the number of grains within a 100 μm×100 μm area of ​​the support substrate 10 was set to about 100 grains, and the substrate was bonded to the LT piezoelectric substrate 20, thinned, polished, and other processes were sequentially performed, and finally a compensation substrate was obtained with a LT piezoelectric substrate having a thickness of 5 μm and a spinel thickness of 250 μm. A filter was manufactured using this compensation substrate, and the final filter was obtained and its characteristics were verified, showing that no noise was generated, i.e., the noise yield was 100%.

[0077] Test Example 2: The average grain size of the support substrate 10 was set to about 45 μm, the number of grain boundary layers was set to >3, the number of grains within a 100 μm × 100 μm area of ​​the support substrate 10 was set to about 50 grains, and the substrate was joined to the LT piezoelectric substrate 20, thinned, polished, and other processes were sequentially performed, and finally a compensation substrate was obtained in which the LT piezoelectric substrate was 5 μm thick and the spinel was 250 μm thick. A filter was manufactured using this compensation substrate, and the characteristics of the final filter were verified, and similarly no noise was generated, i.e., the noise yield was 100%.

[0078] Test Example 3: Unlike Test Example 1, the number of crystal grains within a 100 μm x 100 μm area of ​​the support substrate 10 was set to approximately 3, and the number of crystal grain boundary layers was set to the minimum of 0. The final filter was obtained and its characteristics were verified, with a noise yield of 43%.

[0079] Test Example 4: Unlike Test Example 3, the number of crystal grains within a 100 μm x 100 μm area of ​​the support substrate 10 was set to approximately 5, and the number of crystal grain boundary layers was set to a minimum of 2. The final filter was obtained and its characteristics were verified, with a noise yield of 85%.

[0080] Test Example 5: Unlike Test Example 3, the number of crystal grains within a 100 μm x 100 μm area of ​​the support substrate 10 was set to approximately 7 grains, and the number of crystal grain boundary layers was set to a minimum of 3 layers. When the final filter was obtained and its characteristics were verified, the noise yield was 100%.

[0081] The above are only preferred embodiments of the present disclosure, and are not used to limit the present disclosure, and those skilled in the art can make various modifications and changes to the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure should be included within the protection scope of the present disclosure.

[0082] It should be noted that the specific technical features described in the above specific embodiments may be combined in any suitable manner if not contradictory, and in order to avoid unnecessary duplication, the present disclosure will not describe various possible combination manners again. [Explanation of symbols]

[0083] 10...Support substrate, 20...piezoelectric substrate, 30...electrode, T: thickness of the support substrate, D: grain size.

Claims

1. 1. A substrate structure comprising: a support substrate; and a piezoelectric substrate located on the support substrate, wherein the material of the support substrate is a polycrystalline material, and the porosity of the support substrate is less than 0.0045% or greater than 0.6%, and the number of grain boundary layers of the support substrate is three or more.

2. The substrate structure of claim 1 , wherein the porosity of the support substrate is greater than 0.65%.

3. 3. The substrate structure of claim 2, wherein the porosity of the support substrate is greater than 0.65% and less than 1.5%.

4. 2. The substrate structure according to claim 1, wherein the number of said grain boundary layers is 10 or more.

5. 5. The substrate structure according to claim 4, wherein the number of said grain boundary layers is 40 or less.

6. 5. The substrate structure according to claim 1, wherein the support substrate includes a plurality of crystal grains, and the average grain size of the crystal grains is between 2 μm and 60 μm.

7. 2. The substrate structure according to claim 1, wherein the material of the support substrate is one of polycrystalline spinel, polycrystalline sapphire, polycrystalline silicon, polycrystalline quartz, and polycrystalline aluminum nitride.

8. The substrate structure of claim 1, wherein the support substrate includes a plurality of crystal grains, the average grain size of the crystal grains being less than or equal to one-third of the thickness of the support substrate.The substrate structure of claim 1, wherein the support substrate includes a plurality of crystal grains, the average grain size of the crystal grains being less than or equal to one-third of the thickness of the support substrate.

9. 2. The substrate structure of claim 1, wherein the thickness of the piezoelectric substrate is between 0.1 μm and 10 μm.

10. 2. The substrate structure according to claim 1, wherein the number of crystal grains per unit area of ​​said support substrate is six or more, and said unit area is 100 μm×100 μm.

11. 11. The substrate structure according to claim 10, wherein the number of crystal grains per unit area of ​​the support substrate is 200 grains or less.

12. The substrate structure according to claim 10 , wherein the porosity of the supporting substrate is less than 0.0045% and is equal to or greater than 0.001%.

13. 11. The substrate structure of claim 10, wherein the number of crystal grains per unit area of ​​the support substrate is between 10 and 30 grains, and the unit area is 100 μm×100 μm.

14. 11. The substrate structure of claim 10, wherein the thickness of the piezoelectric substrate is 0.5 to 5 μm, and the thickness of the support substrate is less than 400 μm.

15. 2. The substrate structure according to claim 1, wherein the surface of said support substrate that contacts said piezoelectric substrate has a roughness of 0.8 nm or less.

16. providing a support substrate, the material of the support substrate being a polycrystalline material, and the porosity of the support substrate being less than 0.0045% or greater than 0.6%; and bonding a piezoelectric substrate onto the support substrate to obtain a substrate structure.

17. The step of bonding a piezoelectric substrate onto the support substrate to obtain a substrate structure includes: bonding a piezoelectric substrate onto the support substrate; thinning and polishing a surface of the piezoelectric substrate facing away from the support substrate to a thickness of the piezoelectric substrate of less than 10 μm; and thinning and polishing a surface of the support substrate facing away from the piezoelectric substrate to reduce the thickness of the support substrate to less than 400 μm to obtain a substrate structure.

18. The method for manufacturing a substrate structure according to claim 16, further comprising bonding a piezoelectric substrate onto the supporting substrate to obtain a compensated substrate.

19. 20. The method for manufacturing a substrate structure according to claim 18, comprising the steps of: bonding a piezoelectric substrate onto the support substrate; sequentially thinning and polishing a surface of the piezoelectric substrate facing away from the support substrate to a thickness of the piezoelectric substrate less than 10 μm; and sequentially thinning and polishing a surface of the support substrate facing away from the piezoelectric substrate to a thickness of the support substrate less than 250 μm, thereby obtaining a compensated substrate.

20. A filter comprising the substrate structure according to any one of claims 1 to 15 and an electrode provided on the substrate structure.

21. 20. A duplexer comprising a transmit filter and a receive filter, wherein the transmit filter and / or the receive filter employs a filter as claimed in claim 19.

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