Substrate structure and its manufacturing method, filter, duplexer

Abstract

The present invention provides a substrate structure and its manufacturing method, a filter, and a duplexer that effectively improve the generation of interference noise and enhance the operating performance of a filter device. [Solution] In a substrate structure for a filter device, a duplexer, the substrate structure includes a support substrate 10 and a piezoelectric substrate 20 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%. This substrate structure can effectively improve the generation of interference noise and enhance the operating performance of the filter device.

Description

Technical Field

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

Background Art

[0002] Surface acoustic wave filters are widely applied to various communication devices. In future communication applications, in order to adapt to various more severe external environments, it is strongly required to improve the operation stability of surface acoustic wave filters. Conventional surface acoustic wave filters have the characteristics of low Q value (<1000), low operating frequency, and frequency drift with the change of operating temperature, making it difficult to meet the requirements for filters in high-frequency terminals in the 5G era where the frequency band is becoming increasingly congested. Therefore, conventional surface acoustic wave filters must develop into temperature-compensated filters with high frequencies and stable temperature characteristics.

[0003] warm The temperature-compensated filter Generally adds a A temperature compensation layer is coated or bonded on top. Taking the bonding structure as an example, typically the piezoelectric layer has a temperature compensation function on top of its structure. support layer structure to the piezoelectric layer This will serve as a temperature compensation layer. . After adding the support layer structure, on the one hand, the thickness of the piezoelectric layer can be effectively reduced, increasing the Q value of the device. On the other hand, since the support layer structure has a better coefficient of thermal expansion, the frequency drift phenomenon caused by the temperature of the device can be effectively improved. However, the support layer structure of conventional temperature-compensated filter devices is generally made of high-density and high-speed-of-sound materials. Therefore, while it can improve the temperature drift characteristics of the device, it cannot avoid the generation of a large amount of interference noise.

Summary of the Invention

Problems to be Solved by the Invention

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

[0005] One aspect of the present disclosure provides 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, 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, both pores and grain boundaries within the polycrystalline material can absorb and attenuate sound wave scattering, and furthermore, surface acoustic waves can be consumed during the process of transmission to the inside or bottom surface of the support substrate, thereby significantly reducing sound waves reflected on the top surface and effectively improving the generation of interference noise. filter This can improve the operating performance of the device.

[0007] Another aspect of the present disclosure provides a method for manufacturing a substrate structure, the method for manufacturing a substrate structure comprising the steps of providing a 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 bonding a piezoelectric substrate to the support substrate to obtain a substrate structure.

[0008] Another aspect of the present invention provides a compensating 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, 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 this disclosure effectively reduces the thickness of the piezoelectric substrate by installing a support substrate beneath the piezoelectric substrate, thereby increasing the Q value of the filter and realizing a technological improvement from conventional surface acoustic wave filters to temperature-compensated SAW filters that have high frequency capabilities and stable temperature characteristics. The grain boundaries of polycrystalline materials play a role in absorbing and attenuating sound wave scattering, and surface acoustic waves are transmitted to the interior or underside of the support substrate. The sound waves are consumed by the grain boundaries and pores, and the sound waves reflected from the surface are significantly reduced, thereby reducing noise. For this reason, 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 of noise generation in the manufactured filter device due to fewer crystal boundaries caused by the crystal grain size being too large, and on the other hand, it is possible to prevent the problem of increased pores and a decrease in the Q value of the device caused by the crystal grain size being too small.

[0010] In another aspect of this disclosure, a method for manufacturing a compensating substrate provided by this disclosure includes the steps of providing a 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, and the unit area is 100 μm × 100 μm; and bonding a piezoelectric substrate to the support substrate to obtain a compensating substrate. The method for manufacturing a compensating substrate provided by this disclosure, by bonding a piezoelectric substrate to a support substrate to obtain a compensating substrate, can be applied to temperature-compensated filters, effectively improving the frequency drift due to temperature of the support substrate and increasing the Q value of the device.

[0011] Another aspect of this disclosure is a filter. device Provides the filter device This includes a substrate structure and electrodes provided on the substrate structure.

[0012] Another aspect of this disclosure provides a duplexer which includes a transmit filter and a receive filter, wherein the transmit filter and / or receive filter are the filters device We will adopt this. [Effects of the Invention]

[0013] Compared to conventional technology, the filter provided by this disclosure device is a filter device This effectively improves performance and significantly reduces noise interference. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of the substrate structure provided by some embodiments of this disclosure. [Figure 2] This is a schematic diagram 1 of the structure of a support substrate provided by some embodiments of the present disclosure. [Figure 3] This is a schematic diagram 2 of the structure of a support substrate provided by some embodiments of the present disclosure. [Figure 4] This is a schematic diagram 3 of the structure of a support substrate provided by some embodiments of the present disclosure. [Figure 5] This is a schematic diagram 4 of the structure of a support substrate provided by some embodiments of the present disclosure. [Figure 6] Figure 5 shows a schematic diagram of the structure of a support substrate provided by some embodiments of this disclosure. [Figure 7] This is a schematic diagram 6 of the structure of a support substrate provided by some embodiments of the present disclosure. [Figure 8] This is a schematic diagram of a noise measurement method provided by some embodiments of the present disclosure. [Figure 9] This is flowchart 1 of a method for manufacturing a substrate structure provided by some embodiments of this disclosure. [Figure 10] This is flowchart 2 of a method for manufacturing a substrate structure provided by some embodiments of this disclosure. [Figure 11] This is a schematic diagram of the structure of a filter device provided by some embodiments of this disclosure. [Figure 12] This is a schematic structural diagram of a substrate structure provided by some embodiments of the present disclosure.

Embodiments for Carrying out the Invention

[0015] Conventional temperature-compensated filter devices generally add a support structure to the structure of the piezoelectric layer. However, conventional support structures generally have a high density and select materials with a high sound velocity, which may cause a large amount of noise to be generated during the use of the device. To solve the above problems, the present application provides a new substrate structure, which has a special polycrystalline structure. The filter device adopting the substrate structure can satisfy the basic functions of the filter and can improve the noise.

[0016] Hereinafter, the present application will elaborate and explain in detail the specific structure of the new substrate structure. (Embodiment 1)

[0017] Referring to FIG. 1, the substrate structure provided by this embodiment includes a support substrate 10 and a piezoelectric substrate 20 located on the support substrate 10. Here, 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 substrate structure can effectively improve the generation of interference noise, filter and can improve the operating performance of the device.

[0018] Here, the material of the support substrate 10 is a polycrystalline material. Exemplarily, 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 select an LT (lithium tantalate) or LN (lithium niobate) piezoelectric substrate 20.

[0020] Furthermore, the main cause of sound wave attenuation is absorption of sound waves by the medium. Therefore, in this application, a polycrystalline material having a certain porosity is selected for the support substrate 10. As a result, as shown in Figure 1, factors such as grain boundaries and microdomain non-uniformity (i.e., pores) in the polycrystalline material 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 greater than 0.6%. For example, if 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%, or 0.0010%, and this application does not list them individually.

[0022] If 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%, or 1.4%, etc. Of course, the specific numerical values ​​for the porosity of the support substrate 10 are merely examples and do not imply any restriction on the specific porosity of the support substrate 10. A person skilled in the art can select an appropriate porosity as needed, as long as it is less than 0.0045% or greater than 0.6%.

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

[0024] To further suppress and attenuate interference noise and improve the operating performance of the device, the porosity of the support substrate 10 is selectively 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%.

[0025] Furthermore, in this embodiment, the number of grain boundary layers in the support substrate 10 is selectively 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, it has multiple crystal grains within it. Here, the grain boundary is the boundary between two adjacent crystal grain layers, and corresponding to Figure 3, Figure 3 includes three crystal grain boundary layers (these three crystal grain boundary layers are each shown by black lines in Figure 3).

[0027] Next, grain boundaries and microdomain inhomogeneities (e.g., pores) in the medium can cause scattering of sound waves at the interfaces of these regions, leading to energy attenuation (scattering attenuation). Since there are more grain boundary layers in the support substrate 10 than pores in the support substrate 10, the grain boundary layers can effectively suppress and attenuate sound waves propagating downward from the surface of the electrode 30.

[0028] Multiple grain boundaries in the support substrate 10 absorb and attenuate sound wave scattering. Sound waves transmitted to the interior or underside of the support substrate 10 are consumed by the grain boundaries and pores, significantly reducing the amount of sound waves reflected from the surface. As shown in Figure 1, this reduces noise.

[0029] Referring to Figures 4 to 7, Figures 4 to 7 show the cases where the number of grain boundary layers in the support substrate 10 is a minimum of 0, 1, 2, and 3, respectively. Here, the positions indicated by the white arrows are the locations with the fewest grain boundary layers in the side cross-section of the four types of samples. Furthermore, the grain size corresponding to the location where the number of grain boundary layers decreases is large, and the number of grains per unit area is small. The vicinity of the white arrows is basically the location with the fewest number of grains per unit area, which is 3, 4, 5, and 7 grains, respectively. Filters manufactured using these four types of support substrates 10. device The various characteristics are shown in the table below.

[0030] [Table 1] Of these, the noise measurement method in the table above is as shown in Figure 8, and 21 positions are selected for the fixed coordinate points of each sample and filtered. device If the product is manufactured and its characteristics are tested, and no noise is generated at any of the 21 test points, the noise yield is expressed as 100% (Sample 4 in the table above). If noise is generated at one location, the noise yield can be calculated as 95% based on the ratio.

[0031] As can be seen from the analysis of the table above, the four different samples are all very similar in their remaining characteristics, except that the noise is clearly distinguishable. Thus, it is clear that the number of grain boundary layers definitely affects the noise, and as can be seen from the analysis of the table data, noise generation can be suppressed more effectively when the number of grain boundary layers is ≥ 3.

[0032] In polycrystalline substrates Number of grain boundaries This relates to the size of the crystal grains, particularly the size of the largest crystal grain. Preferably, the number of grain boundaries is controlled by controlling the size of the crystal grains in the polycrystalline substrate. If the size is too large, there are fewer grain boundaries, and noise is more likely to occur in the manufactured filter device. This could lead to the following: If the crystal grain size is too small, pores teeth The Q value of the device increases. of decline This could lead to Therefore, in this embodiment, the number of grain boundary layers is selectively set to 40 or less. Specifically, the specific number of grain boundary layers may be selected by those skilled in the art according to the actual circumstances, and this application does not particularly limit it.

[0033] Selectively, the support substrate 10 provided by this application contains 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 can be between 1 μm and 80 μm. For example, the grain size may be 1 μm, 5 μm, 20 μm, 40 μm, 50 μm, or 80 μm.

[0035] Furthermore, the crystal grains Maximum particle size This is related to the thickness T of the support substrate, and it is necessary that the number of grain boundary layers of the support substrate 10 in this application be 3 or more, and therefore the grain maximum The particle size should be less than or equal to one-third of the thickness T of the support substrate.

[0036] In this embodiment, the thickness of the piezoelectric substrate is selectively between 0.1 μm and 10 μm. Preferably, the thickness of the piezoelectric substrate is 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 between 10 and 100. If the number of crystal grains is too high, the hardness of the support substrate 10 will increase, which is disadvantageous for thinning and polishing the support substrate 10, and will increase material loss and processing time. On the other hand, if the number of crystal grains is too low, the difficulty of processing the support substrate 10 can be reduced, but the material strength of the support substrate 10 will decrease. For this reason, preferably, the number of crystal grains per unit area of ​​the support substrate 10 is between 10 and 30.

[0039] In short, the substrate structure provided by the present invention includes a support substrate 10 and a piezoelectric substrate 20 located on the support substrate 10, wherein 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%. By selecting a polycrystalline material for the material of the support substrate 10 and making the porosity of the support substrate 10 less than 0.0045% or greater than 0.6%, both the pores and grain boundaries in the polycrystalline material can perform absorption and attenuation effects on the scattering of sound waves. Furthermore, surface acoustic waves can be consumed in the process of being transmitted to the interior or bottom surface of the support substrate 10, thereby significantly reducing the amount of sound waves reflected to the top 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 or greater than or equal to 10 layers, and the average grain size is approximately 6 μm.

[0041] The support substrate 10 and the piezoelectric substrate 20 are joined together, and thinning and polishing are performed to obtain a finished substrate structure in which the piezoelectric substrate 20 has a thickness of 5 μm and the support substrate has a thickness T of 250 μm. An electrode 30 is formed on this substrate structure to create a filter. device Obtain the filter device The properties were verified. Filters manufactured using a support substrate 10 with a porosity between 0.0045% and 0.6%. device The characteristics of [the subject] 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 the analysis of the table above, when the porosity is between 0.0045% and 6%, there is still significant noise interference, but when the porosity of the support substrate 10 is selected to be between 1% and 1.5%, the noise can be significantly improved.

[0044] Furthermore, if the porosity of the support substrate 10 is between 1% and 1.5%, a decrease in material strength is unavoidable due to the high porosity. To address this, the average grain size of the support substrate 10 can be appropriately reduced. For example, a support substrate 10 with an average grain size of ≤4 μm may be selected, and in this case, the grain size D of most of the crystal grains is between 1 μm and 2 μm. Thus, the smaller the grain size D of the selected crystal grains, the better the mechanical performance of the material. Macroscopically, increases in yield and tensile strength, surface hardness, and fatigue life are observed. The specific principle is that the finer the crystal grains, the greater the number of crystal grains in a unit volume, and the greater the number of crystal grains involved in deformation, resulting in more uniform deformation and generating large plastic deformation before fracture. Strength and plasticity increase simultaneously, the power at which the material is consumed before fracture is also large, and therefore its toughness is also high. (Example 3)

[0045] A polycrystalline spinel support substrate 10 is selected, characterized by having a porosity between 0.65% and 1%, 40 layers or more and the number of grain boundary layers > 3 layers, and an average grain size of approximately 45 μm.

[0046] The support substrate 10 and the piezoelectric substrate 20 are joined together, and thinning and polishing are performed to obtain a finished substrate structure in which the piezoelectric substrate 20 has a thickness of 5 μm and the support substrate has a thickness T of 250 μm. An electrode 30 is formed on this substrate structure to create a filter. device Obtain the filter device The properties were verified. Filters manufactured using a support substrate 10 with a porosity between 0.0045% and 0.6%. device The characteristics of [the subject] 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 the analysis of the table above, there is still significant noise interference between porosity levels of 0.0045% and 0.6%, and the noise can be significantly improved after selecting a porosity of 0.6% or higher for the support substrate 10. (Example 4)

[0049] A polycrystalline spinel support substrate 10 is selected, characterized in that the porosity of the support substrate 10 is 0.0045% or less, the number of grain boundary layers is 40 or greater than or equal to 10 layers, and the average particle size is approximately 10 μm.

[0050] The support substrate 10 and the piezoelectric substrate 20 are joined together, and thinning and polishing are performed to obtain a finished substrate structure in which the piezoelectric substrate 20 has a thickness of 5 μm and the support substrate has a thickness T of 250 μm. An electrode 30 is formed on this substrate structure to create a filter. device Obtain the filter device The properties were verified. Filters manufactured using a support substrate 10 with a porosity between 0.0045% and 0.6%. device The characteristics of [the subject] 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 the analysis of the table above, there is still significant noise interference when the porosity is between 0.0045% and 0.6%, but the noise can be significantly improved when the porosity of the support substrate 10 is selected to be 0.0045% or less.

[0053] Based on the three embodiments described above, if the support substrate 10 is made of a polycrystalline material and the porosity of the polycrystalline material is selected to be less than 0.0045% or greater than 0.6%, noise can be significantly reduced, thereby improving the operating performance of the device.

[0054] Referring to Figure 9, another aspect of the present disclosure provides a method for manufacturing a substrate structure, the method for manufacturing the substrate structure, Step S100 of providing a support substrate 10, wherein 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 method includes step S200, which involves bonding a piezoelectric substrate 20 onto a support substrate 10 to obtain a substrate structure.

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

[0056] Similarly, the specific material of the piezoelectric substrate 20 may be described in the following description. The coupling process is well known to those skilled in the art and therefore will not be described again in this application.

[0057] Referring also to Figure 10, step S200, which involves selectively bonding a piezoelectric substrate 20 onto a support substrate 10 to obtain a substrate structure, includes steps S210 to 230.

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

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

[0060] For bonding, the bonding process may be carried out under a room temperature, high vacuum environment using an ion activation method.

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

[0062] In step S230, the surface of the support substrate 10 that is separated 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 the substrate structure.

[0063] Referring to Figure 11, another aspect of this disclosure is a filter. device Provides the filter device This includes a substrate structure and electrodes 30 provided on the substrate structure.

[0064] Of these, the electrode 30 is an electrode finger 30, and the specific structure of the substrate structure and its beneficial effects have both been explained in detail previously, so this explanation is omitted here.

[0065] Another aspect of this disclosure provides a duplexer comprising a transmit filter and a receive filter, wherein the transmit filter and / or receive filter employ the filters described above. The specific structure and effects of the filters have all been described in detail previously and are therefore omitted here.

[0066] Referring to Figure 12, the present invention further provides a compensating substrate for use in a filter device, the compensating substrate comprising a support substrate 10 and a piezoelectric substrate 20 located on the support substrate 10, wherein 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 as necessary by those skilled in the art. The compensating substrate described in this embodiment can effectively reduce the thickness of the piezoelectric substrate 20 by placing the support substrate 10 below the piezoelectric substrate 20, thereby increasing the Q value of the filter and realizing a technological improvement from a conventional surface acoustic wave filter to a temperature-compensated SAW filter that has high frequency and stable temperature characteristics. The grain boundaries in polycrystalline materials play a role in absorbing and attenuating sound wave scattering. Surface acoustic waves are transmitted to the interior or bottom surface of the support substrate, and the sound waves are consumed by the grain boundaries and pores. The sound waves reflected from the surface are significantly reduced, thereby contributing to noise reduction. 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 becomes possible to control the size of the crystal grains in the polycrystalline material. This compensated substrate filter allows for control of the number of pores in the polycrystalline substrate by limiting the number of crystal grains per unit area, thereby avoiding a decrease in the device's Q-factor due to excessive pores. .

[0067] Selectively, the number of crystal grains per unit area of ​​the support substrate 10 is 200 or less. In this embodiment, the support substrate 10 must have 200 or fewer crystal grains and at least 6 crystal grains per 100 μm × 100 μm unit area. More preferably, the support substrate 10 has 10 to 100 crystal grains per 100 μm × 100 μm unit area. Exemplarily, the support substrate 10 may have 10, 30, or 100 crystal grains per 100 μm × 100 μm unit area.

[0068] In this filter device using a compensating substrate, per unit area of ​​100 μm × 100 μm of the support substrate 10 By controlling the number of crystal grains within the range of 10 to 100 grains, noise can be improved while ensuring the material's strength remains within an appropriate range, thus avoiding an increase in the difficulty of processing the material. If the number of crystal grains is too high, the hardness of the support substrate 10 increases, making thinning and polishing of the support substrate 10 difficult, thus increasing material loss and processing time. Therefore, controlling the number of crystal grains not only improves noise but also effectively reduces the difficulty of production and processing. The specific number of crystal grains is not limited here and can be set according to the actual needs of those skilled in the art.

[0069] Selectively, the number of grain boundary layers is 3 or more, and / or 40 or less. By limiting the number of grain boundary layers, the arrangement of crystal grains in the cross-section of the support substrate can be controlled. If the number of grain boundary layers is less than 3, there will be too few grain boundaries, making it difficult to effectively absorb and dissipate sound waves, which is detrimental to noise reduction. If the number of grain boundary layers is too large... There are too many stomata, The device's Q-factor decreases. fear There is.

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

[0071] Selectively, the piezoelectric substrate 20 is made of a piezoelectric material and has a piezoelectric effect. In this embodiment 1, the piezoelectric material is lithium tantalate, 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, more preferably 0.5 to 5 μm.

[0072] The method for manufacturing a compensating substrate provided in this embodiment includes the steps of providing a support substrate 10, wherein 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 is 100 μm × 100 μm; and bonding a piezoelectric substrate 20 onto the support substrate 10 to obtain a compensating substrate.

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

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

[0075] Filter provided by the embodiment of the present application device To further illustrate the superior performance, the filter provided by this application device The test will be conducted using this method.

[0076] Test Example 1: In a specific test, the average grain size of the crystal grains in the support substrate 10 was set to approximately 6 μm, the number of crystal grain boundary layers to >10, and the number of crystal grains within a 100 μm × 100 μm area of ​​the support substrate 10 to approximately 100. This was bonded to the LT piezoelectric substrate 20, and thinning, polishing, and other processes were carried out sequentially to obtain a compensating substrate with a final product LT piezoelectric substrate thickness of 5 μm and spinel thickness of 250 μm. This compensating substrate was used to filter device Manufacture and final filter device When its characteristics were verified, no noise was generated, meaning the noise yield was 100%.

[0077] Test Example 2: The average grain size of the crystal grains in the support substrate 10 was set to approximately 45 μm, the number of crystal grain boundary layers was set to >3, and the number of crystal grains within a 100 μm × 100 μm area of ​​the support substrate 10 was set to approximately 50. This was bonded to the LT piezoelectric substrate 20, and thinning and polishing were performed sequentially to obtain a compensating substrate with a final LT piezoelectric substrate thickness of 5 μm and a spinel thickness of 250 μm. This compensating substrate was used to filter device Manufacture and final filter device When the characteristics were verified, no noise was generated, meaning the noise yield was 100%.

[0078] Test Example 3: Unlike Test Example 1, the number of crystal grains within a 100 μm × 100 μm area of ​​the support substrate 10 was set to approximately 3, and the number of crystal grain boundary layers was set to a minimum of 0, and the final filter device Upon obtaining the data and verifying its characteristics, the noise yield was found to be 43%.

[0079] Test Example 4: Unlike Test Example 3, the number of crystal grains within a 100 μm × 100 μm area of ​​the support substrate 10 is set to approximately 5, and the number of crystal grain boundary layers is set to a minimum of 2, and the final filter device Upon obtaining the data and verifying its characteristics, the noise yield was found to be 85%.

[0080] Test Example 5: Unlike Test Example 3, the number of crystal grains within a 100 μm × 100 μm area of ​​the support substrate 10 is set to approximately 7, and the number of crystal grain boundary layers is set to a minimum of 3, and the final filter device Upon obtaining the data and verifying its characteristics, the noise yield was 100%.

[0081] The foregoing are merely preferred embodiments of the Disclosure and are not intended to limit the Disclosure. Those skilled in the art can make various modifications and changes to the Disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the Disclosure should be within the scope of protection of the Disclosure.

[0082] Furthermore, each specific technical feature described in the above specific embodiments can be combined in any suitable manner, provided they do not contradict each other. To avoid unnecessary redundancy, this disclosure will not describe various possible combinations again. [Explanation of Symbols]

[0083] 10...Support substrate, 20... Piezoelectric substrate, 30...electrode, T...Thickness of the support substrate, D...Grain size of the crystal grain.

Claims

1. A filter device, substrate structure, The substrate structure comprises electrodes provided on the substrate structure, The substrate structure includes a support substrate and a piezoelectric substrate located on the support substrate. The material of the support substrate is a polycrystalline material. The number of crystal grains per unit area of ​​the support substrate is 6 or more and 200 or less. A filter device characterized in that the aforementioned unit area is 100 μm × 100 μm.

2. The polycrystalline material has a grain boundary layer inside, The filter device according to claim 1, characterized in that the number of grain boundary layers is three or more, and / or the number of grain boundary layers is 40 or less.

3. The filter device according to claim 1, characterized in that the material of the support substrate is any one of polycrystalline spinel, polycrystalline sapphire, polycrystalline silicon, polycrystalline quartz, and polycrystalline aluminum nitride.

4. The filter device according to claim 1, characterized in that the thickness of the piezoelectric substrate is 0.1 μm to 10 μm.

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