Support layer substrate, composite substrate, its preparation method and electronic device

Abstract

This invention provides a support layer substrate, a composite substrate, a method for fabricating the same, and an electronic device. The support layer substrate has a main support surface, and any sampling area on the main support surface achieves a target roughness. The sampling area is a region with a length less than or equal to 400 micrometers and a width less than or equal to 400 micrometers. The target roughness is expressed as a maximum peak height of less than 20 nanometers after Gaussian filtering, and as an arithmetic mean height of less than 0.7 nanometers after Gaussian filtering. The support layer substrate provided by this invention can achieve better bonding effects and improve bonding efficiency. The resulting composite substrate has higher bonding strength and a higher yield, thereby ensuring the quality of electronic devices and reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of electronic device processing and manufacturing technology, and in particular to a support layer substrate, a composite substrate, a method for preparing the same, and an electronic device thereof. Background Technology

[0002] Surface acoustic wave (SAW) filters are typically fabricated using a piezoelectric substrate with multiple comb-shaped electrodes. High-frequency electrical current is applied to one comb-shaped electrode to generate a SAW, which is then converted into a high-frequency signal by another comb-shaped electrode. In recent years, the high performance requirements of mobile phones have led to higher demands on SAW filters. One such demand is improved temperature stability of the SAW filter chip. Lithium tantalate (LT) and lithium niobate (LN) are piezoelectric materials with large electromechanical coupling coefficients, making them suitable for achieving wideband filtering characteristics. Therefore, LT and LN are widely used as piezoelectric materials in SAW filters. However, LT and LN suffer from poor temperature stability. SAW filters fabricated using these piezoelectric materials exhibit a passband-dependent temperature problem.

[0003] Several techniques have been proposed to achieve piezoelectric materials with large electromechanical coupling coefficients and good temperature stability. For example, a thin piezoelectric substrate can be directly bonded to a support layer substrate with low expansion, which provides support and mechanical coupling. Therefore, temperature stability can be improved by suppressing expansion and contraction caused by temperature changes. A key technology for this type of elastic wave filter is the bonding of the piezoelectric layer substrate and the support layer substrate; the bonding force and other factors after bonding will affect the quality and cost of the elastic wave filter. Summary of the Invention

[0004] The purpose of this invention is to provide a support layer substrate, a composite substrate, a method for preparing the same, and an electronic device, which can improve the bonding area and bonding strength, thereby ensuring the quality of the electronic device and reducing production costs.

[0005] An embodiment of the present invention provides a support layer substrate having a main support surface, wherein any sampling area on the main support surface achieves a target roughness, and the sampling area is a region with a length less than or equal to 400 micrometers and a width less than or equal to 400 micrometers; the target roughness is expressed as a maximum peak height of less than 20 nanometers after Gaussian filtering, and the target roughness is expressed as an arithmetic mean height of less than 0.7 nanometers after Gaussian filtering.

[0006] This invention also provides a composite substrate, including the support layer substrate described in the foregoing embodiments, and further including a piezoelectric layer substrate, wherein the piezoelectric layer substrate is bonded to the main support surface of the support layer substrate.

[0007] This invention also provides a method for preparing a composite substrate, comprising: a polishing step: polishing a support layer material and measuring the roughness of the polished surface of the support layer material until any sampling area on the polished surface reaches the target roughness, thereby obtaining a support layer substrate, and using the polished surface as the main support surface of the support layer substrate; the sampling area is a region with a length less than or equal to 400 micrometers and a width less than or equal to 400 micrometers; the target roughness is expressed as the maximum peak height after Gaussian filtering as less than 20 nanometers; and a bonding step: bonding the piezoelectric layer substrate to the main support surface of the support layer substrate together by direct pressing.

[0008] This invention also provides an electronic device, including the support layer substrate described in the foregoing embodiments, or the composite substrate described in the foregoing embodiments, or the composite substrate prepared by the composite substrate preparation method described in the foregoing embodiments.

[0009] The above embodiments of the present invention have at least one or more of the following beneficial effects: by achieving the target roughness in any sampling area through the main support surface of the support layer substrate provided in this embodiment, better bonding effect can be achieved, bonding efficiency can be improved, and the resulting composite substrate has higher bonding strength and higher yield, thereby ensuring the quality of electronic devices and reducing production costs. Attached Figure Description

[0010] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0011] Figure 1 This is a top view schematic diagram of a support layer substrate provided in an embodiment of the present invention.

[0012] Figure 2 This is a schematic diagram of a composite substrate provided in an embodiment of the present invention.

[0013] Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0014] Figure 4 This is an example diagram illustrating the blade test method from a side view of a composite substrate in an embodiment of the present invention.

[0015] Figure 5 This is an example diagram illustrating the blade test method from a top view of the composite substrate in an embodiment of the present invention.

[0016] Figure 6 This is an example diagram of the peeling distance of the composite substrate under the blade test method in an embodiment of the present invention.

[0017] Figure 7This is a surface inspection image of sample one obtained in Experiment 1 of this invention.

[0018] Figure 8 This is a surface inspection image of sample 1 after thinning, obtained in Experiment 1 of this invention.

[0019] Figure 9 This is a surface detection image of sample two obtained in Experiment 2 of this invention.

[0020] Figure 10 This is a surface inspection image of sample two after thinning, obtained in Experiment 2 of this invention.

[0021] Figure 11 This is a surface detection image of sample three obtained in Experiment 3 of this embodiment of the invention.

[0022] Figure 12 This is a surface inspection image of sample 2 after thinning, obtained in Experiment 3 of this invention.

[0023] Figure 13 This is a surface detection image of sample three obtained in Experiment 4 of this invention.

[0024] Figure 14 This is a surface inspection image of sample five obtained in Experiment 5 of the invention embodiment.

[0025] [Explanation of Labels in the Attached Image]

[0026] 100: Electronic device; 10: Composite substrate; 11: Support layer substrate; 111: Main support surface; 12: Piezoelectric layer substrate; 121: Main surface; 20: Electrode; 200: Blade; D: Peel-off distance. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] It should also be noted that the division of multiple embodiments in this invention is only for the convenience of description and should not constitute a special limitation. Features in various embodiments can be combined and referenced in each other without contradiction.

[0031] like Figure 1 As shown, one embodiment of the present invention provides a support layer substrate 11, which has a main support surface 111. Any sampling region 1111 on the main support surface 111 achieves the target roughness. The sampling region 1111 is a region with a length L less than or equal to 400 μm (micrometers) and a width W less than or equal to 400 μm. The target roughness is expressed as a maximum peak height of less than 20 nm (nanometers) after Gaussian filtering, and the target roughness is expressed as an arithmetic mean height of less than 0.7 nm after Gaussian filtering.

[0032] According to ISO 25178, roughness can be represented by parameters such as arithmetic mean height Sa, maximum height Sz, root mean square height Sq, and maximum peak height Sp. The maximum peak height Sp is the height of the highest point in the defined region (corresponding to sampling region 1111 in this application), and its specific meaning can be found in ISO 25178. In this embodiment, the maximum peak height after Gaussian filtering is denoted as G-Sp. Simply put, in the support substrate 11 provided in this embodiment, for any sampling region 1111 on the main support surface 111 with an L*W less than or equal to 400μm*400μm, G-Sp ≤ 20nm.

[0033] In some embodiments, the length L of the sampling region 1111 is greater than or equal to 50 micrometers, and the width W is greater than or equal to 50 micrometers. That is, in the support layer substrate 11 provided in this embodiment, any sampling region 1111 on the main support surface 111 with an L*W of 50~400μm*50~400μm satisfies G-Sp≤20nm.

[0034] For example, G-Sp ≤ 20 nm in a 50 μm x 50 μm region on the main support surface 111. For example, G-Sp ≤ 20 nm in a 50 μm x 100 μm region on the main support surface 111. For example, G-Sp ≤ 20 nm in a 200 μm x 50 μm region on the main support surface 111. For example, G-Sp ≤ 20 nm in a 200 μm x 250 μm region on the main support surface 111. For example, G-Sp ≤ 20 nm in a 300 μm x 400 μm region on the main support surface 111. For example, G-Sp ≤ 20 nm in a 400 μm x 400 μm region on the main support surface 111.

[0035] G-Sp can be understood as a new Sp value obtained by applying a Gaussian regression filter to the Sp value measured by a roughness measuring device (such as a white light interferometer). The Gaussian regression filter function is as follows: For a detailed explanation, please refer to the definition of the two-dimensional Gaussian function.

[0036] Considering that roughness measurement is easily affected by factors such as the vibration of the measurement stage, particles on the sample surface, and the warpage of the sample itself, the roughness of the main support surface 111 of the support substrate 11 provided in this embodiment of the invention is expressed as the roughness after Gaussian filtering. In actual measurement, Gaussian filtering has little or no impact on the Sp value measurement results. Therefore, in this embodiment, the target roughness can also be expressed as below 20 nm in terms of the maximum peak height and below 0.7 nm in terms of the arithmetic mean height after Gaussian filtering.

[0037] The arithmetic mean height after Gaussian filtering is denoted as G-Sa. G-Sa can be understood as the new Sa value obtained by Gaussian regression filtering the Sa value measured by a roughness measuring device (e.g., a white light interferometer). In any sampling region 1111 of the main support surface 111, G-Sa ≤ 0.7 nm is satisfied. Simply put, in the support layer substrate 11 provided in this embodiment, for any sampling region 1111 on the main support surface 111 with an L*W value less than or equal to 400 μm * 400 μm, G-Sa ≤ 0.7 nm is satisfied.

[0038] In some embodiments, the length L of the sampling region 1111 is greater than or equal to 50 micrometers, and the width W is greater than or equal to 50 micrometers. That is, in the support layer substrate 11 provided in this embodiment, any sampling region 1111 with an L*W of 50~400μm*50~400μm on the main support surface 111 satisfies G-Sa≤0.7nm.

[0039] For example, G-Sa ≤ 0.7 nm in a 50 μm x 50 μm region on the main support surface 111. For example, G-Sa ≤ 0.7 nm in a 50 μm x 150 μm region on the main support surface 111. For example, G-Sa ≤ 0.7 nm in a 100 μm x 100 μm region on the main support surface 111. For example, G-Sa ≤ 0.7 nm in a 250 μm x 50 μm region on the main support surface 111. For example, G-Sa ≤ 0.7 nm in a 250 μm x 350 μm region on the main support surface 111. For example, G-Sa ≤ 0.7 nm in a 300 μm x 400 μm region on the main support surface 111. For example, G-Sa ≤ 0.7 nm in a 400 μm x 400 μm region on the main support surface 111.

[0040] That is, in the support layer substrate 11 provided in some embodiments of the present invention, the roughness of any sampling area 1111 on the main support surface 111 satisfies G-Sp ≤ 20 nm and G-Sa ≤ 0.7 nm. Alternatively, in the support layer substrate 11 provided in some embodiments of the present invention, the roughness of any sampling area 1111 on the main support surface 111 satisfies Sp ≤ 20 nm and G-Sa ≤ 0.7 nm.

[0041] In some embodiments, the maximum peak height of the target roughness meter after Gaussian filtering is expressed as below 15 nanometers, i.e., G-Sp ≤ 15 nm. That is, in the support layer substrate 11 provided in some embodiments of the present invention, any sampling area 1111 on the main support surface 111 satisfies a roughness of G-Sp ≤ 15 nm and G-Sa ≤ 0.7 nm. Alternatively, in the support layer substrate 11 provided in some embodiments of the present invention, any sampling area 1111 on the main support surface 111 satisfies a roughness of Sp ≤ 15 nm and G-Sa ≤ 0.7 nm.

[0042] The target roughness is obtained by measuring the sampling area 1111 using a short-wavelength filter. G-Sp is the Sp value of the sampling area 1111 after processing with the short-wavelength filter. G-Sa is the Sa value of the sampling area 1111 after processing with the short-wavelength filter. The Gaussian filter is divided into four types: (1) Long Wavelength Pass or Low Freq Pass (wavyity) filter, used to remove values ​​in the data that are lower than those input in the long-wavelength cutoff (L-Filter), or frequency components input at spatial frequencies. This surface filtering option is used to remove small-scale roughness components, making large-scale wavy surface structures easier to identify and measure. (2) Short Wavelength Pass or High Freq Pass (roughness) filter, used to remove values ​​in the data that are higher than those input in the short-wavelength cutoff (S-Filter), or frequency components input at spatial frequencies. This surface filtering option is used to remove large-scale wavy components, making small-scale roughness easier to identify and measure. (3) Bandpass filter: blocks data above the cutoff value for lower spatial frequencies or shorter lengths, and below the cutoff value for longer spatial frequencies or longer lengths. (3) Notch filter: the opposite of the bandpass filter. Blocks data with spatial frequencies between the input frequency range or between the wavelength input range. In this embodiment, since the expected roughness Sa of the main support surface 111 is between 0 and 2 nm, the roughness representation after filtering by a shortwave filter is selected.

[0043] In some embodiments, the cutoff wavelength of the shortwave filter is less than 50 micrometers. That is, in this embodiment, the target roughness is measured according to ISO 25178 under measurement conditions where the cutoff wavelength of the shortwave filter is less than 50 micrometers. Specifically, G-Sp is the Sp value measured for the sampling region 1111 under measurement conditions where the cutoff wavelength of the shortwave filter is less than 50 micrometers, and G-Sa is the Sa value measured for the sampling region 1111 under measurement conditions where the cutoff wavelength of the shortwave filter is less than 50 micrometers.

[0044] In a specific embodiment of the present invention, the aforementioned G-Sp and G-Sa are roughness values ​​measured using a Bruker ContourX-200 instrument as the measurement tool and Vision64 software (which provides Gaussian regression filter analysis function). That is, for the support layer substrate 11 provided in this embodiment, the Sp value measured under the measurement conditions of any sampling area 1111 on the main support surface 111 using a Bruker ContourX-200 instrument as the measurement tool and Vision64 software is less than or equal to 20 nm, and the Sa value is less than or equal to 0.7 nm.

[0045] In a specific embodiment of the present invention, the support layer substrate 11 is formed by processing any kind of support layer material, including polycrystalline magnesium aluminum spinel, polycrystalline sapphire, monocrystalline sapphire, etc., that is, the support layer substrate 11 can be formed by processing any one of the support layer materials such as polycrystalline magnesium aluminum spinel, polycrystalline sapphire, monocrystalline sapphire.

[0046] like Figure 2 As shown, this embodiment of the invention also provides a composite substrate 10, which includes a support layer substrate 11 as described in any of the preceding embodiments, and a piezoelectric layer substrate 12. The piezoelectric layer substrate 12 is bonded to the main support surface 111 of the support layer substrate 11. The piezoelectric layer substrate 12 can be, for example, a lithium tantalate substrate. Specifically, the piezoelectric layer substrate 12 and the support layer substrate 11 are bonded to each other by van der Waals forces. The bonding process between the piezoelectric layer substrate 12 and the support layer substrate 11 can be either high-temperature vacuum bonding or room-temperature vacuum bonding. High-temperature vacuum bonding has slightly lower surface requirements for the support layer substrate 11, but due to its high-temperature characteristics, some materials cannot be used. For example, the Curie temperature of lithium tantalate substrates is less than 650 degrees Celsius (°C), making high-temperature bonding inconvenient. The composite substrate 10 provided in this embodiment has higher bonding quality due to the aforementioned support layer substrate 11. Therefore, by using room-temperature bonding technology and utilizing van der Waals forces for adhesion, the bonding area of ​​the composite substrate can reach more than 95%, and the bonding force can reach the MAX level of room-temperature bonding.

[0047] In this embodiment, the composite substrate 10 exhibits a peel distance of less than or equal to 3 mm when tested using the blade test method for the piezoelectric layer substrate 12. For details, please refer to [reference needed]. Figure 4 and Figure 5 Insert the blade 200 between the piezoelectric layer substrate 12 and the support layer substrate 11 provided in this embodiment of the invention, referring to... Figure 6 The peeling distance D of the piezoelectric layer substrate 12 is less than or equal to 3 mm. In the blade test method, the blade thickness is 100-200 micrometers, the insertion force is 1-20 N (Newtons), the insertion speed is 1-3 mm / s (millimeters per second), the insertion angle needs to be as parallel as possible to the support layer substrate 11, and the angle between the blade and the support layer substrate 11 is less than 5°. The implementation methods or conditions of other blade test methods can refer to the traditional blade test methods, and will not be described in detail here.

[0048] In some embodiments, the thickness of the piezoelectric substrate 12 is less than 10 micrometers. The support substrate 11 and the piezoelectric substrate 12 provided in this embodiment are bonded together by van der Waals forces. Even when the piezoelectric substrate 12 is processed to a thickness of less than 10 micrometers, the peeling distance can still be less than or equal to 3 millimeters, resulting in good bonding. This embodiment also provides a method for preparing a composite substrate 10, including a polishing step S1: polishing the support layer material and measuring the roughness of the polished surface of the support layer material until any sampling area on the polished surface reaches the target roughness, thus obtaining the support substrate 11. The polished surface is used as the main support surface 111 of the support substrate 11. The sampling area 1111 is a region with a length less than or equal to 400 micrometers. The target roughness is expressed as a maximum peak height of less than 20 nanometers after Gaussian filtering, and the target roughness is expressed as an arithmetic mean height of less than 0.7 nanometers after Gaussian filtering. Bonding process S2: The piezoelectric layer substrate 12 and the main support surface 111 of the support layer substrate 11 are bonded together by direct pressing.

[0049] That is, the method for preparing the composite substrate 10 provided in this embodiment of the invention first polishes one side of the support layer material to the target roughness (G-Sp≤20nm and G-Sa≤0.7nm) to obtain the support layer substrate 11, and then presses the piezoelectric layer substrate 12 onto the support layer substrate 11, resulting in a composite substrate 10 with higher bonding area and bonding quality. Specifically, after polishing in step S1, a support layer substrate 11 with G-Sp≤20nm and G-Sa≤0.7nm is obtained in any sampling area 1111. In some embodiments, room temperature bonding technology can be used in step S2. By ensuring that the support layer substrate 11 meets the aforementioned specific roughness conditions, even room temperature bonding technology can achieve better bonding strength and a larger bonding area. Therefore, it can be applied to bonding with piezoelectric layer substrates 12 made of different materials, making the material limitations of the piezoelectric layer substrate 12 less significant.

[0050] For example, the specific steps of the composite substrate 10 preparation method provided in some embodiments of the present invention are as follows:

[0051] (X11): Determine the material to be used for the support layer substrate 11, such as effective polycrystalline magnesium aluminum spinel, polycrystalline sapphire, single crystal sapphire, etc. The crystal (support layer material) is processed into the thickness range required for the support layer substrate 11 by multi-wire cutting. At this time, the support layer material is in the state of wire slice, and there will be many parallel wire cutting marks on the surface, which need to be roughed.

[0052] (X12): For coarse grinding, a diamond abrasive slurry with agglomerated diamond particles is selected. The preferred particle size of the diamond particles is 0.5 to 2.5 μm. After agglomeration into spherical shapes, the particle size of the spherical diamond particles ranges from 25 to 40 μm. Selecting spherical diamond particles can reduce the roughness and scratch depth of the grinding surface while ensuring rapid removal. After this step, the Sa of the surface of the support layer material after coarse grinding is 5 to 15 nm.

[0053] (X13): After the support layer material is coarsely ground, fine grinding is required. It is preferred to use a polycrystalline diamond polishing slurry with a particle size of 50-100nm in combination with a tin disc to perform fine grinding on the support layer material. After fine grinding, the surface roughness of the support layer material Sa≤2nm.

[0054] (X14): The support layer material is then subjected to CMP (chemical mechanical polishing), preferably with a 30-80 nm silica sol polishing slurry, and the polishing pressure is preferably 0.05-0.3 kg / cm². 2 The polishing speed is preferably 15-35 RPM. It is only necessary to remove the scratches on the tin pad processing surface. After polishing, the sample area 1111 of the main support surface 111 can be obtained to achieve the target roughness (e.g., G-Sp≤20nm, G-Sa≤0.7nm) and the finished support layer substrate 11.

[0055] (X21): The piezoelectric layer substrate 12 and the main support surface 111 of the support layer substrate 11 are surface ion activated. The ion beam power is preferably 5 to 15 eV (electron volts), and the bonding pressure is preferably 10,000 to 50,000 N (newtons). After pressing, wait for 1 to 2 minutes to obtain the successfully bonded composite substrate 10.

[0056] Steps (X11) to (X14) are examples of specific implementation steps for step S1, and step (X21) is an example of specific implementation steps for step S2. The specific process conditions for the aforementioned rough grinding, fine grinding, polishing, and pressing steps can be adjusted according to actual needs.

[0057] Reference Figure 3 This invention also provides an electronic device 100, including a support layer substrate 11 as described in any of the foregoing embodiments, or a composite substrate 10 as described in any of the foregoing embodiments, or a composite substrate 10 prepared by the aforementioned method of preparing the composite substrate 10. Figure 3As shown, the electronic device 100 can be an elastic wave device, specifically, for example, a SAW device, and more specifically, a Tc-SAW device. The electronic device 100 includes a composite substrate 10 formed by bonding a support layer substrate 11 and a piezoelectric layer substrate 12, and also includes electrodes 20 (referring to the electrodes of a conventional SAW device) disposed on the main surface 121 (the side of the piezoelectric layer substrate 12 facing away from the support layer substrate 11) of the piezoelectric layer substrate 12. Alternatively, the electronic device 100 can also be an LED device or other devices, and the support layer substrate 11 can be combined with other functional substrates.

[0058] The following experiments, from Experiment 1 to Experiment 7, illustrate the beneficial effects of the support substrate 11, composite substrate 10, the preparation method of composite substrate 10, and electronic device 100 provided in the embodiments of the present invention.

[0059] Experiment 1

[0060] Magnesium aluminum spinel was selected as the support layer material. After multi-wire dicing, the ingot was ground using 30μm aggregated spherical diamond particles. Then, a 100nm single-crystal diamond solution was used for rough polishing with a tin tray. Finally, a 80nm silica sol polishing solution was used for fine polishing to obtain the finished spinel substrate. The thickness of the finished spinel substrate was 250μm, and the roughness of its main support surface 111 met the requirements of G-Sp≤20nm and G-Sa≤0.7nm. This spinel substrate was then vacuum-bonded to a 200μm thick lithium tantalate substrate at room temperature. The bonding ion beam power was 15eV, and the bonding pressure was 15000N for 1 min. The resulting sample was as shown in the image. Figure 7 As shown, the bonding area is almost 100%. Even after reducing the thickness of the lithium tantalate substrate from 200 μm to 5 μm, the bonding area remains close to 100%, and there is no piezoelectric layer peeling at the edges (e.g.). Figure 8 (As shown).

[0061] Experiment 2

[0062] Magnesium aluminum spinel was selected as the support layer material. After multi-wire dicing, the ingot was ground using 30μm aggregated spherical diamond particles. Then, a 100nm single-crystal diamond solution was used with a tin tray for rough polishing. Finally, an 85nm silica sol polishing solution was used for fine polishing to obtain the finished product. The thickness of the finished spinel substrate was 250μm, and the roughness of its polished surface met the requirements of G-Sp > 20nm and G-Sa ≤ 0.7nm. This spinel substrate was then vacuum-bonded to a 200μm thick lithium tantalate substrate at room temperature. The bonding ion beam power was 15eV, and the bonding pressure was 15000N for 1 min. The resulting sample was as follows: Figure 9 As shown, the bonding area is only about 75%. After processing the lithium tantalate substrate thickness from 200 μm to 5 μm, as... Figure 10The edges shown exhibit obvious piezoelectric layer peeling. Due to G-Sp > 20 nm, the interior of sample two is filled with numerous small areas of failed bonding, and the lithium tantalate substrate shows extensive peeling when thinned to 5 μm.

[0063] Experiment 3

[0064] Magnesium aluminum spinel was selected as the support layer material. After multi-wire dicing, the ingot was ground using 30μm aggregated spherical diamond particles. Then, a 100nm single-crystal diamond solution was used with a tin tray for rough polishing. Finally, a 85nm silica sol polishing solution was used for fine polishing to obtain the finished spinel substrate. The thickness of the finished spinel substrate was 250μm, and the roughness of its polished surface met the requirements of G-Sp ≤ 20nm and G-Sa > 0.7nm. This spinel substrate was then vacuum-bonded to a 200μm thick lithium tantalate substrate at room temperature. The bonding ion beam power was 15eV, and the bonding pressure was 15000N for 1 min. The resulting sample was as follows: Figure 11 As shown, the bonding area is only about 75%. After processing the lithium tantalate substrate thickness from 200 μm to 5 μm, as... Figure 12 The edge shown has obvious piezoelectric layer peeling.

[0065] Experiment 4

[0066] Magnesium aluminum spinel was selected as the support layer material. After the ingot was diced by multi-wire cutting, it was ground using 30μm aggregated spherical diamond particles. Then, a 100nm single-crystal diamond solution was used for rough polishing with a tin tray. Finally, a 90nm silica sol polishing solution was used for fine polishing to obtain the finished spinel substrate. The thickness of the finished spinel substrate was 250μm, and the roughness of its polished surface met the requirements of G-Sp > 20nm and G-Sa > 0.7nm. This spinel substrate was then vacuum-bonded to a 200μm thick lithium tantalate substrate at room temperature. The bonding ion beam power was 15eV, and the bonding pressure was 15000N for 1 min. The resulting sample was as follows: Figure 13 As shown, the bonding area is only about 40%. After the thickness of the lithium tantalate substrate was processed from 200μm to 5μm, there was obvious piezoelectric layer peeling at the edge.

[0067] Experiment 5

[0068] Magnesium aluminum spinel was selected as the support layer material. After multi-wire dicing, the ingot was ground using 30μm aggregated spherical diamond particles. Then, a 100nm particle size single-crystal diamond solution was used for rough polishing with a tin tray. Finally, a 100nm particle size silica sol polishing solution was used for fine polishing to obtain the finished spinel substrate. The thickness of the finished spinel substrate was 250μm, and the roughness of its polished surface met the requirements of G-Sp being much greater than 20nm and G-Sa being much greater than 0.7nm. This spinel substrate was then vacuum-bonded to a 200μm thick lithium tantalate substrate at room temperature. The bonding ion beam power was 15eV, and the bonding pressure was 15000N for 1 min. The resulting sample was as follows: Figure 14 As shown, there are basically no successful bonding areas on the entire surface of the substrate. The bonding strength test using the blade test method is NG, making it impossible to perform thinning operations on the sample lithium tetratantalate substrate.

[0069] Experiment Six

[0070] Single-crystal sapphire was selected as the support layer material. After multi-wire dicing, the ingot was ground using 30μm aggregated spherical diamond particles. Finally, it was finely polished using an 80nm particle size silica sol polishing solution to obtain a finished single-crystal sapphire substrate with a thickness of 250μm. The roughness of the polished surface met the requirements of G-Sp≤20nm and G-Sa≤0.7nm. This spinel substrate was then vacuum-bonded to a 200μm thick lithium tantalate substrate at room temperature. The bonding ion beam power was 15eV, and the bonding pressure was 15000N for 1 min. The resulting sample achieved a six-bonded area of ​​approximately 100%. Even after reducing the thickness of the lithium tantalate substrate from 200μm to 5μm, the bonding area remained close to 100%, with no piezoelectric layer peeling at the edges.

[0071] Experiment 7

[0072] Polycrystalline sapphire was selected as the support layer material. After grinding the polycrystalline sapphire substrate, 30μm aggregated spherical diamond particles were used for further grinding. Then, a 100nm particle size single-crystal diamond solution was used with a tin tray for rough polishing. Finally, a 60nm particle size silica sol polishing solution was used for fine polishing to obtain the finished polycrystalline sapphire substrate. The thickness of the finished polycrystalline sapphire substrate was 250μm, and the roughness of its polished surface met the requirements of G-Sp≤20nm and G-Sa≤0.7nm. This spinel substrate was vacuum bonded to a 200μm thick lithium tantalate substrate at room temperature. The bonding ion beam power was 15eV, and the bonding pressure was 15000N for 1min. The resulting sample had a bonding area of ​​almost 100%. After the thickness of the lithium tantalate substrate was reduced from 200μm to 5μm, the bonding area was still close to 100%, and there was no piezoelectric layer peeling at the edges.

[0073] The experimental results data for Experiments 1 to 7 are shown in Table 1. The bonding result Pass means successful bonding, and the bonding result NG means unsuccessful bonding. The bonding result is Pass when the peeling distance is less than or equal to 3 mm.

[0074] Table 1

[0075]

[0076] Based on the results of experiments one through seven above, it can be seen that when the roughness of the main support surface 111 of the support substrate 11 meets the requirement that G-Sp is within 20 nm, a higher bonding area with the piezoelectric substrate 12 can be obtained using the support substrate 11, resulting in a better bonding effect. When the roughness of the main support surface 111 of the support substrate 11 meets the requirements that G-Sp is within 20 nm and G-Sa is within 0.7 nm, a higher bonding area with the piezoelectric substrate 12 can be obtained with higher bonding strength, making it less prone to peeling. Therefore, the support substrate 11 provided in this embodiment can achieve a better bonding effect, improve bonding efficiency, and the resulting composite substrate 10 has higher bonding strength and higher yield, thereby ensuring the quality of the electronic device 10 and reducing production costs.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A support layer substrate, characterized in that, It has a main support surface, and any sampling area on the main support surface achieves the target roughness. The sampling area is a region with a length of less than or equal to 400 micrometers and a width of less than or equal to 400 micrometers. The target roughness is expressed as the maximum peak height after Gaussian filtering, which is greater than or equal to 5.6 nanometers and less than or equal to 20 nanometers. The target roughness is also expressed as the arithmetic mean height after Gaussian filtering, which is greater than or equal to 0.17 nanometers and less than or equal to 0.7 nanometers.

2. The support layer substrate as described in claim 1, characterized in that, The target roughness is expressed as the maximum peak height after Gaussian filtering, which is greater than or equal to 5.6 nanometers and less than or equal to 15 nanometers.

3. The support layer substrate as described in claim 1, characterized in that, The target roughness is the roughness obtained by measuring the sampling area based on a shortwave filter.

4. The support layer substrate as described in claim 3, characterized in that, The cutoff wavelength of the shortwave filter is less than 50 micrometers.

5. The support layer substrate as described in claim 1, characterized in that, The support layer substrate is formed by processing any kind of support layer material, including polycrystalline magnesium aluminum spinel, polycrystalline sapphire, and monocrystalline sapphire.

6. A composite substrate, characterized in that, The substrate includes a support layer substrate as described in any one of claims 1 to 5, and further includes a piezoelectric layer substrate, wherein the piezoelectric layer substrate is bonded to the main support surface of the support layer substrate.

7. The composite substrate as described in claim 6, characterized in that, The piezoelectric layer substrate and the support layer substrate are bonded to each other by van der Waals forces.

8. The composite substrate as described in claim 7, characterized in that, When the composite substrate is tested using the blade test method, the peeling distance of the piezoelectric layer substrate is less than or equal to 3 mm.

9. The composite substrate as described in claim 7, characterized in that: The thickness of the piezoelectric layer substrate is less than 10 μm.

10. The composite substrate as described in claim 7, characterized in that: The bonding area of ​​the composite substrate is over 95%.

11. A method for preparing a composite substrate, characterized in that, include: Polishing process: The support layer material is polished, and the roughness of the polished surface of the support layer material is measured until any sampling area on the polished surface reaches the target roughness, thus obtaining the support layer substrate. The polished surface is used as the main support surface of the support layer substrate. The sampling area is a region with a length of less than or equal to 400 micrometers and a width of less than or equal to 400 micrometers. The target roughness is expressed as the maximum peak height after Gaussian filtering, which is greater than or equal to 5.6 nanometers and less than or equal to 20 nanometers, and the target roughness is expressed as the arithmetic mean height after Gaussian filtering, which is greater than or equal to 0.17 nanometers and less than or equal to 0.7 nanometers. Bonding process: The piezoelectric layer substrate and the main support surface of the support layer substrate are bonded together by direct pressing.

12. The method for preparing a composite substrate as described in claim 11, characterized in that: The bonding process employs room temperature bonding technology.

13. An electronic device, characterized in that, The composite substrate includes the support layer substrate as described in any one of claims 1 to 5, or the composite substrate as described in any one of claims 6 to 10, or the composite substrate prepared by the method described in any one of claims 11 to 12.

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