An ultrathin lithium tantalite piezoelectric wafer and a preparation process thereof

Abstract

The application discloses an ultrathin lithium tantalate piezoelectric wafer and a preparation process thereof, and belongs to the technical field of ultrathin lithium tantalate wafer preparation. The preparation process comprises the following steps: first, ion implantation is performed on the lithium tantalate wafer, the ion implantation dose gradually increases from the center of the wafer to the outside, and pre-annealing treatment is performed at 200-500 DEG C; second, the ion implantation surface and the base wafer of the lithium tantalate wafer are surface-activated and bonded to obtain a bonded body; third, the lithium tantalate wafer of the bonded body is thinned to a thickness of 30-150 mu m; and fourth, annealing treatment is performed on the thinned bonded body, and an ultrathin lithium tantalate piezoelectric wafer is obtained by stripping the implanted layer of the lithium tantalate wafer. The method can obtain the 30-150 mu m ultrathin lithium tantalate piezoelectric wafer without damage, meets the production demand of the ultrathin lithium tantalate piezoelectric wafer at present, and can obtain a piezoelectric hetero thin film.

Description

Technical Field

[0001] This application relates to an ultrathin lithium tantalate piezoelectric wafer and its fabrication process, belonging to the field of ultrathin lithium tantalate wafer fabrication technology. Background Technology

[0002] Lithium tantalate piezoelectric wafers, as a key functional material, are widely used in high-frequency filters, surface acoustic wave devices, optical modulators and sensors due to their advantages such as high Curie temperature, low dielectric loss, excellent piezoelectric response and good chemical stability. They are one of the core basic materials for cutting-edge technology industries such as 5G communication and the Internet of Things.

[0003] Currently, wire cutting and laser cutting remain the mainstream methods for fabricating lithium tantalate piezoelectric wafers. However, due to the inherent mechanical strength characteristics of lithium tantalate piezoelectric wafers—they are relatively brittle and have limited fracture resistance—when the wafer thickness is reduced to the ultra-thin range of less than 100 micrometers, internal stress easily concentrates, leading to the propagation of microcracks. This results in a sharp increase in the fragmentation rate during the cutting process, making it difficult to consistently obtain complete, defect-free ultra-thin lithium tantalate wafers. This technological bottleneck significantly limits the use of traditional wire cutting and laser cutting processes in the fabrication of ultra-thin lithium tantalate wafers.

[0004] With the development of high-frequency electronic devices towards miniaturization, high frequency, and high reliability, the market demand for ultrathin lithium tantalate piezoelectric wafers is increasing daily. Therefore, breaking through the limitations of traditional cutting processes and developing a new method for non-destructive, efficient, and scalable fabrication of ultrathin lithium tantalate wafers has become a key issue that urgently needs to be addressed in the field of piezoelectric materials. Summary of the Invention

[0005] To address the aforementioned issues, a fabrication process for ultrathin lithium tantalate piezoelectric wafers is provided. This process is based on the fabrication method of heterobonded substrates. By pre-annealing the substrate wafer, performing partitioned ion implantation on the lithium tantalate wafer, and thinning the bond, ultrathin lithium tantalate piezoelectric wafers of 30-150 μm can be obtained non-destructively, meeting the current production requirements for ultrathin lithium tantalate piezoelectric wafers.

[0006] This application provides a fabrication process for ultrathin lithium tantalate piezoelectric wafers, comprising the following steps: Step 1: Ion implantation is performed on the lithium tantalate wafer, with the ion implantation dose gradually increasing from the inside to the outside, and the substrate wafer is pre-annealed at 200-500℃. Step 2: Activate and bond the ion implantation surface of the lithium tantalate wafer and the substrate wafer to obtain a bonded body; Step 3: Thin the lithium tantalate wafer of the bonding assembly to a thickness of 30-150μm; Step 4: Anneal the thinned bond and peel it off to obtain an ultrathin lithium tantalate piezoelectric wafer.

[0007] Currently, the fabrication of heterogeneous bonding substrates based on lithium tantalate typically involves first ion implantation into a lithium tantalate wafer to obtain a wafer containing a thin film layer, an implanted layer, and a residual layer. The thin film layer is then bonded to the substrate wafer. Afterward, heating and annealing are performed to vaporize the implanted ions, achieving the separation of the thin film layer and the residual layer, resulting in a heterogeneous bonding substrate and a lithium tantalate wafer with the residual layer. However, the residual layer lithium tantalate wafer obtained under this method is still relatively thick, not an ultra-thin lithium tantalate wafer. Furthermore, the separation process can cause cracks in the residual layer lithium tantalate wafer, and in severe cases, breakage. Therefore, the separated lithium tantalate wafers are usually unusable and are treated as waste.

[0008] This application found in its research that the thick lithium niobate residual layer, if thinned using a thinning process, is more prone to breakage during peeling, making it difficult to obtain ultra-thin, damage-free lithium tantalate piezoelectric wafers. Therefore, without improvement, this method cannot produce ultra-thin, damage-free lithium tantalate piezoelectric wafers. Based on this finding, it is currently believed that there are two reasons for the breakage of the thinned lithium niobate residual layer: First, there is internal stress in the substrate wafer, which is released during the high-temperature peeling process, causing the ultra-thin lithium niobate piezoelectric wafer to form fragments or cracks during peeling. Second, because the ion implantation concentration is uniform throughout the implanted layer, the peeling process of the ultra-thin lithium niobate piezoelectric wafer (ultra-thin residual layer) exhibits multi-point random peeling. Therefore, the peeling process generates additional tensile force on the ultra-thin lithium niobate piezoelectric wafer, which can also cause breakage and affect quality.

[0009] To address the first reason, this application pre-annealing the substrate wafer to eliminate the stress generated during the production or processing of the lithium tantalate wafer, thereby reducing the impact of the substrate wafer on the stripping process and reducing the stripping fragmentation rate. To address the second reason, this application improves the ion implantation of the lithium tantalate wafer by using H ions or H and He ions for gradient ion implantation, resulting in an implantation layer with the ion implantation dose gradually increasing from the inside to the outside. This allows for stripping from the outside to the inside during the annealing process in step (4), reducing the generation of additional stripping pull force and further reducing the stripping fragmentation rate.

[0010] Optionally, the first step of ion implantation of the lithium tantalate wafer can be H ion implantation or H and He ion co-implantation, with an ion implantation energy of 50-500 keV. The specific operation is as follows: S10: Perform one-step H-ion implantation or H and He ion co-implantation on the entire surface of the lithium tantalate wafer, which consists of a central circle, a first outer ring, and a second outer ring from the inside out. When implanting only H ions, the H-ion implantation dose is 4.0 × 10⁻⁶. 16 -7.8×10 16 ions / cm 2 When H and He ions are co-implanted, the H ion implantation dose is 2.0 × 10⁻⁶. 16 -3.9×10 16 ions / cm 2 The He ion implantation dose was 5 × 10⁻⁶. 15 -1×10 16 ions / cm 2 ; S20: Two-step ion implantation is performed on the crystal planes of the first and second outer rings. When implanting H ions alone, the H ion implantation dose is 2 × 10⁻⁶. 16 -2.3×10 16 ions / cm 2 When H and He ions are co-implanted, the H ion implantation dose is 1.0 × 10⁻⁶. 16 -1.2×10 16 ions / cm 2 The He ion implantation dose was 2.5 × 10⁻⁶. 15 -3×10 15 ions / cm 2 , S30: Three-step ion implantation is performed on the crystal plane of the second outer ring. When implanting only H ions, the H ion implantation dose is 2.2 × 10⁻⁶. 16 -3.0×10 16 ions / cm 2 When H and He ions are co-implanted, the H ion implantation dose is 1.1 × 10⁻⁶. 16 -1.5×10 16 ions / cm 2 The He ion implantation dose was 3 × 10⁻⁶. 15 -4×10 15 ions / cm 2 .

[0011] The dosage setting of this ion implantation serves two purposes: first, it enables peeling from the outside in, reducing the fragmentation rate of ultrathin lithium niobate piezoelectric single crystal wafers; second, it ensures the thickness uniformity of ultrathin wafers and heterogeneous films.

[0012] The aforementioned ion implantation is achieved through three steps to create a partitioned arrangement of ion concentrations on the implantation surface of the lithium tantalate wafer. For the lithium tantalate wafer, H ions or H and He ions are implanted together. After H ions are implanted into the lithium tantalate wafer, a neat weakening layer is formed. When H ions are implanted alone, a heterogeneous thin film substrate with higher film uniformity can be obtained. When H and He ions are implanted together, He ions can be captured by the plateau defects formed by H ions and these plateau defects are expanded and combined with each other through physical action, thereby promoting the peeling of the single crystal piezoelectric substrate.

[0013] Optionally, the area ratio of the central circle, the first outer ring, and the lithium tantalate wafer is 1:(1-2.5):(2-4).

[0014] This diameter ratio setting enables uniform peeling from the outside of the wafer inwards, while also reducing the warpage of the ultrathin lithium tantalate piezoelectric single crystal after peeling, thus improving its surface quality.

[0015] Optionally, the first step of pre-annealing the substrate wafer takes 4-72 hours.

[0016] The temperature and time of the pre-annealing can effectively release the internal stress in the substrate wafer, while avoiding the reintroduction of internal stress and crystallization damage to the substrate wafer, so as to obtain a high-quality substrate wafer. This high-quality substrate wafer can then be used to obtain a high-quality heterobonded substrate and an ultrathin lithium niobate piezoelectric wafer.

[0017] Optionally, the second step involves activating the H-ion implantation surface of the lithium tantalate wafer and the substrate wafer using plasma activation or surface activation methods.

[0018] Optionally, the third step of thinning specifically involves: S1: Use 1500#-3000# grinding wheels for the first thinning to a thickness of 50-200μm for the lithium tantalate wafer; S2: Use 6500#-8000# grinding wheels for a second thinning process to achieve a lithium tantalate wafer thickness of 30-150μm.

[0019] Due to the inherent characteristics of lithium tantalate wafers, a single thinning process using a coarse grinding wheel can lead to wafer breakage or the introduction of internal stress, making it difficult to obtain a lossless ultrathin lithium tantalate wafer later. Therefore, this application employs a two-step thinning process to reduce the impact of the thinning process on the lithium tantalate wafer, thereby obtaining a lossless ultrathin lithium tantalate piezoelectric wafer. Based on the characteristics of lithium tantalate wafers, the final thinning thickness in step S2 cannot be less than 30 μm. If it is less than 30 μm, firstly, the low mechanical strength of the wafer itself will cause fragmentation during the peeling process; secondly, the thinning stress will cause film damage during the thinning process, making it difficult to obtain a complete ultrathin lithium tantalate piezoelectric wafer.

[0020] In addition, this thinning process is designed based on the characteristics of lithium tantalate wafers themselves. The above thinning process can ensure the acquisition of ultra-thin lithium tantalate piezoelectric wafers with no damage, low internal stress, and high surface flatness.

[0021] Optionally, the specific operation of the fourth step of annealing is as follows: Keep warm at 120-150℃ for 5-30 hours, then at 160-180℃ for 5-30 hours, and finally at 180-230℃ for 10-15 hours.

[0022] The annealing temperature is related to the ion implantation concentration of the lithium tantalate wafer. At this temperature, gradual peeling can be achieved to obtain a non-destructive ultrathin lithium tantalate piezoelectric wafer. At the same time, it can avoid introducing thermal stress into the ultrathin lithium tantalate piezoelectric wafer and improve its quality.

[0023] Optionally, the substrate wafer is made of a material selected from silicon carbide, silicon, silicon nitride, gallium nitride, gallium oxide, diamond, sapphire, or silicon dioxide.

[0024] Optionally, the substrate wafer is made of silicon carbide.

[0025] Optionally, the initial thickness of the lithium tantalate wafer and the substrate wafer is 200μm-1000μm, and the diameter of the lithium tantalate wafer and the substrate wafer is 2 inches-12 inches, preferably 6 inches or more.

[0026] According to another aspect of this application, an ultrathin lithium tantalate piezoelectric wafer prepared by the fabrication process of any of the above-described ultrathin lithium tantalate piezoelectric wafers is provided, wherein the thickness of the ultrathin lithium tantalate piezoelectric wafer is 30-150 μm.

[0027] The beneficial effects of this application include, but are not limited to: 1. Based on the fabrication process of the ultrathin lithium tantalate piezoelectric wafer of this application, the original fabrication process of heterobonded substrate is improved, which can obtain ultrathin lithium tantalate piezoelectric wafer on the basis of obtaining heterobonded substrate, greatly saving production costs and facilitating mass production of ultrathin lithium tantalate piezoelectric wafer.

[0028] 2. According to the fabrication process of the ultrathin lithium tantalate piezoelectric wafer of this application, the heterobonded substrate and the ultrathin lithium tantalate piezoelectric wafer obtained by batch production have high consistency, which improves the operational stability of the device.

[0029] 3. The fabrication process of ultrathin lithium tantalate piezoelectric wafers according to this application breaks through the limitation that traditional wire cutting and laser cutting cannot fabricate ultrathin lithium tantalate wafers. Ultrathin lithium tantalate piezoelectric wafers can be obtained non-destructively through non-cutting methods, which can meet the industry's demand for ultrathin lithium tantalate piezoelectric wafers and broaden the application prospects of lithium tantalate wafers. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the structure of the lithium tantalate wafer involved in the embodiments and comparative examples of this application.

[0031] 1. Central circle; 2. First outer ring; 3. Second outer ring. Detailed Implementation

[0032] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0033] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0034] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art.

[0035] Example 1 This embodiment relates to a fabrication process for a 2-inch ultrathin lithium tantalate piezoelectric wafer, including the following steps: Step 1: Perform H-ion implantation (ion implantation energy of 50 keV) on lithium tantalate wafers (200 μm thickness) and pre-anneal the Si substrate wafers (200 μm thickness) at 200 °C for 72 h. The specific procedure for H ion implantation is as follows: S10: Reference Figure 1 A one-step H-ion implantation was performed on the entire surface of a lithium tantalate wafer, consisting of a central circle 1, a first outer ring 2, and a second outer ring 3, from the inside out. The implantation dose was 4.0 × 10⁻⁶. 16 ions / cm 2 ; S20: Perform two-step H ion implantation on the crystal planes of the first outer ring 2 and the second outer ring 3, with an implantation dose of 2.0 × 10⁻⁶. 16 ions / cm 2 ; S30: Three-step H ion implantation is performed on the crystal plane of the second outer ring 3, with an implantation dose of 2.2 × 10⁻⁶. 16 ions / cm 2The area ratio of the central circle 1, the first outer ring 2, and the second outer ring 3 is 1:1:2. Step 2: Surface activation and bonding are performed on the H-ion implantation surface of the lithium tantalate wafer and the substrate wafer to obtain a bonded body; Step 3: Thin the lithium tantalate wafer of the bonding assembly to a thickness of 150μm. The specific thinning operation is as follows: S1: The first thinning was performed using a 3000# grinding wheel until the thickness of the lithium tantalate wafer was 200μm; S2: A second thinning process is performed using an 8000# grinding wheel until the lithium tantalate wafer thickness is 150μm; Step 4: The thinned bond body is annealed at 150℃ for 30 hours, then at 180℃ for 30 hours, and finally at 230℃ for 15 hours to obtain an ultrathin lithium tantalate piezoelectric wafer, and at the same time, a composite heterofilm is obtained.

[0036] Example 2 This embodiment relates to a fabrication process for a 6-inch ultrathin lithium tantalate piezoelectric wafer, including the following steps: Step 1: Perform H ion implantation (ion implantation energy of 500 keV) on lithium tantalate wafer (thickness 1000 μm) and pre-anneal the Si substrate wafer (thickness 1000 μm) at 200 °C for 72 h. The specific procedure for H ion implantation is as follows: S10: Reference Figure 1 A one-step H-ion implantation was performed on the entire surface of a lithium tantalate wafer, consisting of a central circle 1, a first outer ring 2, and a second outer ring 3, from the inside out. The implantation dose was 7.8 × 10⁻⁶. 16 ions / cm 2 ; S20: Two-step H ion implantation is performed on the crystal planes of the first outer ring 2 and the second outer ring 3, with an implantation dose of 2.3 × 10⁻⁶. 16 ions / cm 2 ; S30: Three-step H ion implantation is performed on the crystal plane of the second outer ring 3, with an implantation dose of 3.0 × 10⁻⁶. 16 ions / cm 2 The area ratio of the central circle 1, the first outer ring 2, and the second outer ring 3 is 1:2.5:4. Step 2: Surface activation and bonding are performed on the H-ion implantation surface of the lithium tantalate wafer and the substrate wafer to obtain a bonded body; Step 3: Thin the lithium tantalate wafer of the bonding assembly to a thickness of 30μm. The specific thinning operation is as follows: S1: The first thinning was performed using a 3000# grinding wheel until the thickness of the lithium tantalate wafer was 50μm; S2: A second thinning process is performed using an 8000# grinding wheel until the lithium tantalate wafer thickness is 30μm; Step 4: The thinned bond body is annealed at 120℃ for 5 hours, then at 160℃ for 5 hours, and finally at 180℃ for 10 hours to obtain an ultrathin lithium tantalate piezoelectric wafer, and at the same time, a composite heterofilm is obtained.

[0037] Example 3 This embodiment relates to a fabrication process for an 8-inch ultrathin lithium tantalate piezoelectric wafer, including the following steps: Step 1: Perform H-ion implantation (200 keV energy) on lithium tantalate wafer (400 μm thickness) and pre-anneal the SiC substrate wafer (500 μm thickness) at 300 °C for 12 h. The specific procedure for H ion implantation is as follows: S10: Reference Figure 1 A one-step H-ion implantation was performed on the entire surface of a lithium tantalate wafer, consisting of a central circle 1, a first outer ring 2, and a second outer ring 3, from the inside out. The implantation dose was 7.4 × 10⁻⁶. 16 ions / cm 2 ; S20: Perform two-step H ion implantation on the crystal planes of the first outer ring 2 and the second outer ring 3, with an implantation dose of 2.1 × 10⁻⁶. 16 ions / cm 2 ; S30: Three-step H ion implantation is performed on the crystal plane of the second outer ring 3, with an implantation dose of 2.5 × 10⁻⁶. 16 ions / cm 2 The area ratio of the central circle 1, the first outer ring 2, and the second outer ring 3 is 1:2:3. Step 2: Plasma activation and bonding are performed on the H-ion implantation surface of the lithium tantalate wafer and the substrate wafer to obtain a bonded body; Step 3: Thin the lithium tantalate wafer of the bonding assembly to a thickness of 60μm. The specific thinning operation is as follows: S1: The first thinning was performed using a 3000# grinding wheel until the thickness of the lithium tantalate wafer was 80μm; S2: A second thinning process is performed using an 8000# grinding wheel until the lithium tantalate wafer thickness is 60μm; Step 4: The thinned bond body is annealed at 150℃ for 10 hours, then at 170℃ for 10 hours, and finally at 190℃ for 10 hours to obtain an ultrathin lithium tantalate piezoelectric wafer, and at the same time, a composite heterofilm is obtained.

[0038] Example 4 The difference between this embodiment and Embodiment 3 is that the specific operation of H ion implantation is as follows: S20: Perform two-step H ion implantation on the crystal planes of the first outer ring 2 and the second outer ring 3, with an implantation dose of 1.0 × 10⁻⁶. 16 ions / cm 2 The rest is the same as in Example 3.

[0039] Example 5 The difference between this embodiment and Embodiment 3 is that the specific operation of H ion implantation is as follows: S30: Perform three-step H ion implantation on the crystal plane of the second outer ring 3, with an implantation dose of 1.5 × 10⁻⁶. 16 ions / cm 2 The rest is the same as in Example 3.

[0040] Example 6 The difference between this embodiment and embodiment 3 is that the area ratio of the central circle 1, the first outer ring 2, and the second outer ring 3 is 1:3:6, while the rest is the same as in embodiment 3.

[0041] Example 7 The difference between this embodiment and Embodiment 3 is that the specific thinning operation is as follows: S1: The lithium tantalate wafer was thinned to a thickness of 60 μm using a 3000# grinding wheel, and the rest was the same as in Example 3.

[0042] Example 8 The difference between this embodiment and Embodiment 3 is that in the fourth step, the thinned bond body is annealed at 190°C for 30 hours, while the rest is the same as in Embodiment 3.

[0043] Example 9 The difference between this embodiment and Embodiment 3 is that the first step, ion implantation, is performed as follows: S10: A one-step H and He ion co-implantation is performed on the entire surface of the lithium tantalate wafer, which consists of a central circle, a first outer ring, and a second outer ring from the inside out. The H ion implantation dose is 2.0 × 10⁻⁶. 16 ions / cm 2 The He ion implantation dose was 5 × 10⁻⁶. 15 ions / cm 2 ; S20: Two-step H and He ion implantation is performed on the crystal planes of the first and second outer rings, with an H ion implantation dose of 1.0 × 10⁻⁶. 16 ions / cm 2 The He ion implantation dose was 2.5 × 10⁻⁶. 15 ions / cm 2 ; S30: Three-step ion implantation is performed on the crystal plane of the second outer ring. When H and He ions are implanted together, the H ion implantation dose is 1.1 × 10⁻⁶.16 ions / cm 2 The He ion implantation dose was 3 × 10⁻⁶. 15 ions / cm 2 The rest is the same as in Example 3.

[0044] Example 10 The difference between this embodiment and Embodiment 3 is that the first step, ion implantation, is performed as follows: S10: A one-step H and He ion co-implantation is performed on the entire surface of the lithium tantalate wafer, which consists of a central circle, a first outer ring, and a second outer ring from the inside out. The H ion implantation dose is 3.9 × 10⁻⁶. 16 ions / cm 2 The He ion implantation dose was 1×10⁻⁶. 16 ions / cm 2 ; S20: Two-step H and He ion implantation is performed on the crystal planes of the first and second outer rings, with an H ion implantation dose of 1.2 × 10⁻⁶. 16 ions / cm 2 The He ion implantation dose was 3 × 10⁻⁶. 15 ions / cm 2 ; S30: Three-step ion implantation is performed on the crystal plane of the second outer ring. When H and He ions are implanted together, the H ion implantation dose is 1.5 × 10⁻⁶. 16 ions / cm 2 The He ion implantation dose was 4 × 10⁻⁶. 15 ions / cm 2 The rest is the same as in Example 3.

[0045] Comparative Example 1 The difference between this comparative example and Example 3 is that the SiC substrate wafer is not pre-annealed at 300°C for 12 hours; that is, the SiC substrate wafer is not treated in any way. Otherwise, it is the same as Example 3.

[0046] Comparative Example 2 The difference between this comparative example and Example 3 is that the SiC substrate wafer was pre-annealed at 600°C for 12 hours, while the rest is the same as Example 3.

[0047] Comparative Example 3 The difference between this comparative example and Example 3 is that in the H-ion implantation step S10, the entire surface of the lithium tantalate wafer, consisting of a central circle 1, a first outer ring 2, and a second outer ring 3 arranged sequentially from the inside out, is subjected to one-step H-ion implantation, with an implantation dose of 3.0 × 10⁻⁶. 16 ions / cm 2 The rest is the same as in Example 3.

[0048] Comparative Example 4 The difference between this comparative example and Example 3 is that the specific operation of H ion implantation is as follows: A one-step H-ion implantation was performed on the entire surface of a lithium tantalate wafer, consisting of a central circle 1, a first outer ring 2, and a second outer ring 3, from the inside out. The implantation dose was 7.4 × 10⁻⁶. 16 ions / cm 2 Only one H ion implantation was performed, and the rest was the same as in Example 3.

[0049] Test Example 1 Ultrathin lithium tantalate piezoelectric wafers and composite heterostructures were prepared according to the methods described in the above embodiments and comparative examples. Fifty wafers were prepared for each embodiment or comparative example. Fragmentation rate statistics and TTV (Total Television Value) tests of the composite heterostructure layer were performed. The test results are shown in Table 1. Fragmentation rate = Number of fragments / Total number.

[0050] Table 1

[0051] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A fabrication process for an ultrathin lithium tantalate piezoelectric wafer, characterized in that, Includes the following steps: Step 1: Ion implantation is performed on the lithium tantalate wafer. The ion implantation dose gradually increases from the center of the wafer outwards, and the ion implantation dose at the center of the wafer is not less than 4.0 × 10⁻⁶. 16 ions / cm 2 The substrate wafer is pre-annealed at 200-500℃. Step 2: Activate and bond the implantation surface of the lithium tantalate wafer and the substrate wafer to obtain a bonded body; Step 3: Thin the lithium tantalate wafer of the bonding assembly to a thickness of 30-150μm; Step 4: Anneal the thinned bond body and peel it off to obtain an ultrathin lithium tantalate piezoelectric wafer and a composite heterofilm; The first step involves ion implantation of the lithium tantalate wafer, either H ion implantation or a combination of H and He ions. The ion implantation energy is 50-500 keV. The specific operation is as follows: S10: Perform one-step ion implantation on the entire surface of the lithium tantalate wafer, which consists of a central circle, a first outer ring, and a second outer ring from the inside out. For single H ion implantation, the H ion implantation dose is 4.0 × 10⁻⁶. 16 -7.8×10 16 ions / cm 2 When H and He ions are co-implanted, the H ion implantation dose is 2.0 × 10⁻⁶. 16 -3.9×10 16 ions / cm 2 The He ion implantation dose was 5 × 10⁻⁶. 15 -1×10 16 ions / cm 2 ; S20: Two-step ion implantation is performed on the crystal planes of the first and second outer rings. When implanting H ions alone, the H ion implantation dose is 2 × 10⁻⁶. 16 -2.3×10 16 ions / cm 2 When H and He ions are co-implanted, the H ion implantation dose is 1.0 × 10⁻⁶. 16 -1.2×10 16 ions / cm 2 The He ion implantation dose was 2.5 × 10⁻⁶. 15 -3×10 15 ions / cm 2 ; S30: Three-step ion implantation is performed on the crystal plane of the second outer ring. When implanting only H ions, the H ion implantation dose is 2.2 × 10⁻⁶. 16 -3.0×10 16 ions / cm 2 When H and He ions are co-implanted, the H ion implantation dose is 1.1 × 10⁻⁶. 16 -1.5×10 16 ions / cm 2 The He ion implantation dose was 3 × 10⁻⁶. 15 -4×10 15 ions / cm 2 ; The area ratio of the central circle, the first outer ring, and the second outer ring is 1:(1-2.5):(2-4); The third step of thinning is as follows: S1: Use 1500#-3000# grinding wheels for the first thinning to a thickness of 50-200μm for the lithium tantalate wafer; S2: Use a 6500#-8000# grinding wheel for a second thinning process until the lithium tantalate wafer thickness is 30-150μm; The fourth step, annealing, is performed as follows: Keep warm at 120-150℃ for 5-30 hours, then at 160-180℃ for 5-30 hours, and finally at 180-230℃ for 10-15 hours.

2. The fabrication process of the ultrathin lithium tantalate piezoelectric wafer according to claim 1, characterized in that, The first step is to pre-anneal the substrate wafer for 4-72 hours.

3. The fabrication process of the ultrathin lithium tantalate piezoelectric wafer according to claim 1, characterized in that, The second step involves activating the H-ion implantation surface of the lithium tantalate wafer and the substrate wafer using plasma activation or surface activation methods.

4. The fabrication process of the ultrathin lithium tantalate piezoelectric wafer according to claim 1, characterized in that, The substrate wafer is made of a material selected from silicon carbide, silicon, silicon nitride, gallium nitride, potassium oxide, diamond, sapphire, or silicon dioxide.

5. The fabrication process of the ultrathin lithium tantalate piezoelectric wafer according to claim 1, characterized in that, The initial thickness of the lithium tantalate wafer and the substrate wafer is 200μm-1000μm, and the diameter of the lithium tantalate wafer and the substrate wafer is 2 inches-12 inches.

6. The ultrathin lithium tantalate piezoelectric wafer prepared by the fabrication process according to any one of claims 1-5 is characterized in that, The thickness of the ultrathin lithium tantalate piezoelectric wafer is 30-150 μm.

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