Patterned epitaxial heterostructure and preparation method thereof

Abstract

The invention discloses a patterned epitaxial heterostructure and a preparation method thereof. The preparation method comprises the following steps: 1) forming a patterned hard mask layer on a single crystal substrate; (2) a heterostructure is deposited on the surface of the patterned hard mask of the substrate in a high-temperature epitaxial mode, and the heterostructure selectively grows in a substrate window area exposed by the hard mask; the heterostructure comprises an epitaxial sacrificial layer and an epitaxial functional layer which grow in sequence; (3) the patterned hard mask is removed, and the heterostructure material growing on the hard mask is stripped; and 4) stripping and releasing the patterned epitaxial functional layer borne by the sacrificial layer from the substrate by selectively corroding the epitaxial sacrificial layer. Through selective area epitaxy limited by a hard mask, a sacrificial layer sensitive to a chemical environment and a photoetching process are effectively isolated, and an innovative manufacturing path with high-precision patterning and excellent crystal quality is provided for preparation of a high-performance heterogeneous integrated device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor thin films, and particularly relates to a patterned epitaxial heterostructure and a preparation method thereof. BACKGROUND

[0002] The key technology for realizing high-performance heterostructure devices is to peel off and transfer the single-crystal thin film of micro-nano scale from its original growth substrate to a functional substrate such as a flexible polymer or a silicon-based circuit. This technology aims to combine the excellent physical properties (such as high carrier mobility, ferroelectricity, and ferromagnetism) of single-crystal materials (such as functional oxides, III-V semiconductors, etc.) with the powerful logic functions of traditional silicon-based CMOS circuits or the mechanical deformability of flexible substrates, thereby breaking through the performance bottleneck of single-material systems. The core technology for achieving the above goal is epitaxial lift-off (ELO), which basically involves pre-growth of a sacrificial layer between the single-crystal substrate and the functional thin film. The sacrificial layer can be selectively etched by a specific solvent (such as acid, strong base, or water). When the sacrificial layer is dissolved, the functional thin film can be released without damage. However, how to effectively combine the ELO technology with the micro-nano patterning process necessary for device function is still a major challenge and fundamental contradiction in current technology development.

[0003] A typical method is "transfer first, then patterning". This method first epitaxially grows a large-area, non-patterned sacrificial layer and a functional thin film on the original substrate, then uses epitaxial lift-off (ELO) technology to peel off and transfer the entire functional thin film from the original substrate to the target substrate, and finally implements lithography and dry etching for patterning the functional thin film. The main defects of this scheme include: functional oxide thin films usually have high hardness and chemical stability, which are prone to process damage during dry etching, thereby affecting device performance; in addition, when the target substrate is a flexible material, its deformation and process compatibility during etching also pose significant challenges.

[0004] Another type of method is called "patterning the functional film first, then transferring". The core idea of this method is to complete the patterning on the original substrate of the functional film before transferring it to the target substrate. However, the process generally followed by this type of method, i.e. epitaxially growing a sacrificial layer on the entire substrate first, then performing various patterning operations on the sacrificial layer, causes a fundamental contradiction that is difficult to overcome. Whether the functional film is directly patterned using traditional photolithography and etching techniques or is selectively epitaxially grown by making a mask, it inevitably involves a photolithography process. In this process, chemical reagents such as photoresist, developer, and remover, and deionized water will directly contact and prematurely corrode or damage the underlying sacrificial layer with active chemical properties, resulting in a very narrow process window or even complete failure. For example, the widely used water-soluble sacrificial layer Sr3Al2O6 (SAO) is quickly dissolved in the development and cleaning steps of photolithography; while if an acid-soluble sacrificial layer (such as SrVO3) is used, the problem of acid intolerance of most functional oxide films arises, making selective etching difficult to achieve.

[0005] Therefore, there is an urgent need to develop an innovative technical solution that can combine the high-precision advantages of patterning technology and the efficient transfer capability of ELO technology, and fundamentally avoid the direct contact between the sacrificial layer and the chemicals of the patterning process. SUMMARY

[0006] The present application aims to overcome the deficiencies in the prior art and provides a patterned epitaxial heterostructure and a preparation method thereof.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: A preparation method of a patterned epitaxial heterostructure, comprising the following steps: 1) forming a patterned hard mask layer on a single crystal substrate; 2) epitaxially depositing a heterostructure on the patterned hard mask surface of the substrate at high temperature, the heterostructure being selectively grown on the substrate window area exposed by the hard mask; the heterostructure comprising an epitaxial sacrificial layer and an epitaxial functional layer grown in sequence; 3) removing the patterned hard mask and peeling off the heterostructure material grown above the hard mask; 4) releasing the patterned epitaxial functional layer carried by the sacrificial layer from the substrate by selectively etching the epitaxial sacrificial layer.

[0008] Further improvements of the present application are that the hard mask layer is a multilayer structure, comprising a metal sacrificial layer for final wet peeling, a diffusion barrier layer for preventing interatomic mutual diffusion between the layers at high temperature, and a high-temperature-resistant rigid layer for protecting the underlying structure and defining the pattern.

[0009] The further improvement of the present application is that the metal sacrificial layer is made of aluminum, the diffusion barrier layer is made of tungsten, titanium nitride, tantalum nitride or a combination thereof, and the high-temperature-resistant rigid layer is made of nickel, platinum or iridium.

[0010] The further improvement of the present application is that before the high-temperature epitaxial deposition in step 2), an in-situ interface activation treatment step in the vacuum cavity of the deposition device is further included to remove the surface contaminants of the substrate window area exposed by the hard mask and activate the surface, thereby preparing for the later epitaxial sacrificial layer.

[0011] The further improvement of the present application is that the in-situ interface activation treatment is oxygen plasma treatment or low-energy argon ion beam treatment.

[0012] The further improvement of the present application is that the high temperature in step 2) is in the range of 400-700℃.

[0013] The further improvement of the present application is that the epitaxial sacrificial layer is water-soluble Sr3Al2O6.

[0014] The further improvement of the present application is that the selective etching in step 4) is carried out in deionized water. The step of removing the patterned hard mask includes selectively laterally etching the metal sacrificial layer using a strong alkali solution, thereby stripping the diffusion barrier layer, the high-temperature-resistant rigid layer and the heterostructure covering thereon.

[0015] The further improvement of the present application is that before step 4), a step of spin-coating a polymer support layer on the sample surface is further included to fix the relative position of the patterned epitaxial functional layer and provide mechanical support during the stripping and transferring process; wherein the spin-coating of the polymer support layer includes a soft baking process, and the baking temperature is lower than the glass transition temperature of the polymer support layer, and the temperature is 80-100℃.

[0016] A patterned epitaxial heterostructure is prepared by the preparation method.

[0017] Compared with the prior art, the present application has at least the following beneficial technical effects: The primary innovation of the present application lies in the structural design of the hard mask. The structure discards the traditional Al / Ni double-layer system and adopts a sandwich structure with a central diffusion barrier layer, such as Al / W / Ni.

[0018] The thickness of the aluminum layer at the bottom is 50-100 nm, which continues to serve as the sacrificial metal layer that can be selectively etched by a strong alkali solution (such as KOH).

[0019] The thickness of the nickel layer at the top is 20-50 nm, which maintains its high-temperature-resistant and rigid characteristics and ensures the stability of the pattern under high-temperature conditions.

[0020] The core innovation is the interposed tungsten (or titanium nitride) diffusion barrier layer with a thickness of 5 to 15 nanometers. As a typical high-melting-point metal (melting point exceeding 3000 degrees Celsius), tungsten has a dense atomic structure that can effectively block the mutual diffusion between the upper layer of nickel atoms and the lower layer of aluminum atoms at a high temperature of 400 to 700 degrees Celsius. This barrier layer acts as a strong firewall, fundamentally solving the peeling failure problem caused by the formation of nickel-aluminum alloy in traditional Al / Ni hard masks at high temperatures, thereby significantly widening the temperature application range of subsequent epitaxial growth processes.

[0021] The second key innovation of the present application is the introduction of an in-situ interface activation treatment step before high-temperature epitaxial growth. After the preparation of the hard mask is completed, the exposed window area of the substrate inevitably has organic residue and adsorption layers. After the sample is sent to the epitaxial growth equipment (such as PLD), a short (such as 1-5 minutes) oxygen plasma treatment or low-energy argon ion bombardment is performed on the sample in the vacuum chamber before formal growth. This step can effectively remove the contaminants in the window area and activate the substrate surface. Although it may not completely restore the ideal epitaxial surface to atomic-level flatness, it is sufficient to convert the contaminated surface into a clean surface that can support highly textured growth, greatly improving the crystalline quality of the subsequent thin film.

[0022] After the interface activation is completed, high-temperature epitaxial growth of the sacrificial layer and deposition of the functional oxide thin film layer are sequentially performed in the pre-set window area. The material selection of the substrate, epitaxial sacrificial layer, and epitaxial functional layer needs to follow the principle of crystal structure matching and similar lattice constants to ensure the realization of high-quality heteroepitaxial growth. Since the sacrificial layer is not in contact with any photoetching chemical reagent or potassium hydroxide alkaline solution during its entire life cycle (from the growth stage to the final corrosion stage), its structural integrity is fully guaranteed.

[0023] After growth, the transfer is completed by combining wet stripping with dry transfer. First, the Al layer in the hard mask is etched with KOH solution to strip the mask and the "waste" thin film above it. Then, the epitaxial sacrificial layer as the "root" is dissolved by a selective etching solution, and the patterned, high-quality functional thin film array is released from the substrate. Finally, the nano-transfer technology based on adhesion is used to complete the transfer of the thin film array. This technology uses elastic stamps such as polydimethylsiloxane (PDMS) to control the adhesion between the stamp and the thin film array by precisely controlling the speed of contact and separation, thereby achieving parallel "picking up" and "placing" of the thin film array, and finally transferring it from the original substrate to the target substrate. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the accompanying drawings needed to be used in the specific embodiments or prior art description will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0025] Figure 1 Schematic diagram of the preparation method of the patterned epitaxial heterostructure in an embodiment of the present application.

[0026] Figure 2 (a) scanning electron microscope (SEM) image and (b) atomic force microscope (AFM) image of the LaNiO3 film transferred to the silicon substrate in Embodiment 2 of the present application.

[0027] Element number explanation: 1-single crystal oxide substrate, 2-photoresist, 3-metal sacrificial layer, 4-diffusion barrier layer, 5-high-temperature-resistant rigid layer, 6-epitaxial sacrificial layer, 7-epitaxial thin film layer, 8-PMMA, 9-PDMS, 10-PET flexible target substrate. DETAILED DESCRIPTION

[0028] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.

[0029] In the description of the present application, it should be understood that, when used in the specification and the appended claims, the terms "comprise" and "include" indicate the presence of described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or sets thereof.

[0030] It should also be understood that the terms used in the present application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the present application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0031] It should be further understood that the term "and / or" used in the present application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0032] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0033] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] Example 1 This embodiment provides a method for preparing a patterned SRO (strontium ruthenium oxide) epitaxial film on an STO single-crystal substrate 1 and transferring it onto a flexible PET target substrate 9, such as... Figure 1 As shown in the figure. In this embodiment, strontium titanate (SrTiO3, STO) is selected as the single-crystal substrate, water-soluble tristrontium hexaaluminate (Sr3Al2O6, SAO) is selected as the epitaxial sacrificial layer, and strontium ruthenate (SrRuO3, SRO) is selected as the epitaxial functional layer. The selection of this material system is based on its excellent lattice matching characteristics: all three are perovskite or perovskite-like structures, and their (pseudo)cubic lattice constants (STO ≈ 3.905 Å, SRO ≈ 3.93 Å, and 1 / 4 lattice constant of SAO ≈ 3.96 Å) are highly matched, laying the foundation for achieving high-quality heteroepitaxial growth.

[0035] Step 1: As Figure 1 As shown, the pre-patterning process is performed. A (001) oriented STO single-crystal substrate 1 is provided, which is ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, and then dried. A photoresist pattern 2 is formed on the surface of the single-crystal substrate using a standard photolithography process.

[0036] Step 2: Deposition of the three-layer hard mask. The substrate with patterned photoresist is placed in a magnetron sputtering system, and three layers of hard mask material are deposited sequentially: an 80nm thick Al layer as a metal sacrificial layer 3, a 10nm thick W layer as a diffusion barrier layer 4, and a 30nm thick Ni layer as a high-temperature rigid layer 5. After deposition, the sample is immersed in hot acetone for ultrasonic lift-off to remove the photoresist and the overlying metal film, thereby obtaining a selectively patterned Al / W / Ni three-layer composite hard mask on the surface of substrate 1.

[0037] Step three: interface activation of the selected area window. Before the epitaxial growth, in-situ interface activation is performed. For example, a low-energy argon ion beam (e.g. energy 50-100 eV) is introduced to the sample surface for 1-2 minutes in an environment with an oxygen partial pressure of 1 Pa to remove the adsorption layer and organic residue on the exposed substrate 1 surface in the hard mask window area.

[0038] Step four: deposition of the epitaxial layer and functional layer. After interface activation, the vacuum is not broken and high-temperature epitaxial growth is directly started. First, the substrate temperature is raised to 650°C, and a 30 nm thick SAO layer is grown as an epitaxial sacrificial layer 6 under an oxygen pressure of 10 Pa. Then, the substrate temperature is raised to 700°C, and a 50 nm thick SRO layer is grown as an epitaxial functional layer 7 under an oxygen pressure of 10 Pa. The thin film will grow in a high-quality texture on the substrate window area, while it will be deposited in a low-quality polycrystalline or amorphous form on the Ni layer 5 on top of the hard mask.

[0039] Step five: stripping of the three-layer hard mask layer. The sample after growth is taken out of the chamber. It is immersed in a 1 mol / L KOH solution for the first wet stripping at 40°C. The KOH solution will laterally etch the bottom Al metal sacrificial layer 3 from the side of the hard mask. As the Al layer is completely removed, the W / Ni stack above it and the low-quality SAO / SRO thin film deposited thereon are also stripped as a whole. After cleaning and drying, a high-quality patterned SAO / SRO epitaxial heterostructure consistent with the hard mask pattern is obtained on the substrate 1 surface.

[0040] Step six: stripping of the functional layer. A polymer support layer is spin-coated on the sample surface, for example, PMMA with a molecular weight of 950K is selected to form a support layer 8 with a thickness of about 1.2 μm. Then, the sample is placed on a hot plate at 90°C for soft baking for 5 minutes. This temperature is sufficient to completely evaporate the solvent of PMMA and solidify it, but is lower than the glass transition temperature, so that the side wall microchannels are not sealed due to thermal reflow. Subsequently, the sample is gently immersed in a beaker containing deionized water for the second wet stripping. The deionized water will penetrate from the edge of the pattern to completely dissolve the SAO epitaxial sacrificial layer 6 as the foundation in a lateral hollowing manner. After several hours, the patterned SRO functional layer 7 is completely separated from the single-crystal substrate 1. At this time, the released SRO thin film array is fixed and retained on the original substrate surface by the PMMA support layer.

[0041] Step seven: transfer of functional layer. Thin film transfer is performed using nano-imprint technology. A microscope equipped with a micromanipulator is used to precisely align and adhere the PDMS stamp 9 to the SRO thin film array. By rapidly peeling off the PDMS stamp (pick-up process), the SRO thin film array is completely "picked up" from the STO growth substrate by virtue of the significantly enhanced adhesion between the PDMS stamp and the SRO thin film at high speed. Subsequently, the PDMS stamp with the SRO thin film is again aligned and adhered to the final PET flexible target substrate 10 by means of the micromanipulator. By slowly peeling off the PDMS stamp (place process), the SRO thin film array is precisely "placed" on the target substrate at this time, the adhesion is weakened. Finally, the target substrate with the PMMA / SRO stack is immersed in an acetone solution to completely remove the PMMA support layer, and thus the patterned SRO epitaxial functional layer 7 is finally successfully transferred from the STO growth substrate to the PET target substrate 10.

[0042] The performance of the finally obtained patterned SRO thin film transferred to the PET substrate is characterized, and the results are as follows: (1) crystal structure characterization: the (002) diffraction peak of the SRO thin film is tested by high-resolution X-ray diffraction (HRXRD) rocking curve, and the full width at half maximum (FWHM) is only 0.2°, indicating that the thin film has extremely high crystalline quality and orientation consistency. (2) Electrical performance characterization: the resistivity of the SRO thin film is measured at room temperature by four-probe method, and the resistivity is as low as 250 μΩ·cm, showing excellent conductive properties, which is comparable to the performance of the SRO epitaxial thin film grown directly on the original STO substrate, proving that the transfer process does not introduce obvious damage.

[0043] In summary, by introducing a thermally stable multilayer hard mask and a selective in-situ interface activation process, the application successfully decouples the patterning step from the high-temperature epitaxial growth step, and realizes the final damage-free release and transfer without contacting any photoresist chemicals, using a water-soluble sacrificial layer. The process design is ingenious, solves the fundamental contradiction of the prior art, and has extremely high application value.

[0044] Example 2 This embodiment provides a method for preparing a patterned LaNiO3 epitaxial thin film on a SrTiO3 single crystal substrate, which demonstrates the applicability of the application in different material systems and process parameters.

[0045] Step one: provide a (001) oriented SrTiO3 single crystal substrate, the cleaning process is the same as in Example 1. Form a photoresist pattern by standard photolithography process.

[0046] Step two: deposition of the three-layer hard mask. A 90 nm thick Al as a metal sacrificial layer, a 10 nm thick TiN as a diffusion barrier layer, and a 40 nm thick Pt as a high-temperature resistant rigid layer were sequentially deposited. After thermal acetone stripping, a patterned Al / TiN / Pt three-layer composite hard mask was obtained.

[0047] Step three: interface activation of the selected window. In the PLD chamber, the sample surface was treated with oxygen plasma (power 50 W) for 2 minutes in an environment with an oxygen partial pressure of 5 Pa to clean and activate the exposed SrTiO3 substrate surface.

[0048] Step four: deposition of the epitaxial layer and the functional layer. First, the substrate temperature was raised to the lower limit value of the temperature range claimed in the present application, i.e. 400°C, and a 25 nm thick SAO layer was epitaxially grown as an epitaxial sacrificial layer under an oxygen pressure of 1 Pa. Subsequently, without changing the substrate temperature, a 60 nm thick LaNiO3 layer was epitaxially grown as an epitaxial functional layer under the same oxygen pressure.

[0049] Step five: stripping of the three-layer hard mask layer. The process was the same as in Example 1.

[0050] Step six: stripping of the functional layer. A PMMA support layer was spin-coated on the sample surface, followed by soft baking at 80°C (the lower limit value of the temperature range claimed in the present application) on a hot plate for 5 minutes. The subsequent deionized water stripping process was the same as in Example 1.

[0051] Step seven: transfer of the functional layer. The process was the same as in Example 1, and finally the patterned LaNiO3 thin film array was transferred to a silicon (Si) substrate.

[0052] The performance of the finally obtained patterned LaNiO3 thin film transferred to the silicon substrate was characterized, as shown in Figure 2 The results show that: (1) structural and morphological characterization: Figure 2 The scanning electron microscope (SEM) image of (a) shows that the thin film array was completely transferred to the target substrate, with clear pattern profile and no obvious wrinkles or cracks. Figure 2The atomic force microscope (AFM) image of (b) further reveals its excellent surface quality, with a root mean square (RMS) roughness of only 0.439 nm within a scanning range of 5 μm x 5 μm, indicating that the film surface reaches atomic-level flatness, which is crucial for constructing high-quality heterojunction devices. (2) Electrical performance characterization: The room temperature resistivity is measured by the four-probe method, and the value is about 450 μΩ·cm, showing excellent metal conductive properties. In summary, the LaNiO3 film prepared by the process has excellent surface morphology, crystal quality and conductive properties, and can be used as a high-performance perovskite oxide epitaxial electrode, and can form a high-quality heterojunction interface with the subsequent integrated ferroelectric, piezoelectric and other functional layers.

[0053] Example 3 The present embodiment provides a method for preparing a patterned CoFe2O4 (cobalt ferrite) epitaxial film on a MgO single crystal substrate, further verifying the feasibility of the present application under a wider process window.

[0054] Step one: provide a (001) oriented MgO single crystal substrate, clean and make a photoresist pattern.

[0055] Step two: deposition of three layers of hard mask. 100 nm thick Al is deposited as a metal sacrificial layer, 12 nm thick TaN is deposited as a diffusion barrier layer, and 25 nm thick Ir is deposited as a high-temperature resistant rigid layer. After heat acetone stripping, a patterned Al / TaN / Ir three-layer composite hard mask is obtained.

[0056] Step three: interface activation of the selected window. The same low-energy argon ion beam treatment as in Example 1 is used.

[0057] Step four: deposition of epitaxial layer and functional layer. The substrate temperature is raised to the middle value of the temperature range claimed in the present application, i.e. 550℃, and a 30 nm thick SAO layer is epitaxially grown as an epitaxial sacrificial layer, and a 100 nm thick CoFe2O4 layer is epitaxially grown as an epitaxial functional layer under an oxygen pressure of 5 Pa.

[0058] Step five: stripping of the three-layer hard mask layer. The process is the same as in Example 1.

[0059] Step six: stripping of the functional layer. A PMMA support layer is spin-coated on the sample surface, followed by soft baking at 100℃ (the upper limit of the temperature claimed in the present application) for 5 minutes. The subsequent deionized water stripping process is the same as in Example 1.

[0060] Step seven: transfer of the functional layer. The process is the same as in Example 1, and finally the patterned CoFe2O4 film array is transferred to a flexible polyimide (PI) and silicon substrate.

[0061] The results of rocking curve test of high resolution X-ray diffraction (HRXRD) show that the full width at half maximum (FWHM) of (002) diffraction peak of the in-situ grown film, the film transferred to the silicon (Si) substrate and the film transferred to the polyimide (PI) flexible substrate is 1.27°, 1.35° and 1.31° respectively. The FWHM value remains stable before and after the transfer, which powerfully proves that the transfer process does not damage the excellent crystalline quality of the film. Through the vibrating sample magnetometer (VSM) test, the CoFe2O4 film after the transfer exhibits a clear and saturated hysteresis loop. The coercive field (H c ) in the in-plane and out-of-plane directions is similar, both about 1.34 kOe, indicating that the film has excellent hard magnetic properties and weak magnetic anisotropy.

[0062] Comparative Example 1 In order to highlight the superiority of the present application, the comparative experiment is carried out by using the "epitaxy first and patterning later" process described in the background art.

[0063] Step one: On the (001) oriented STO single crystal substrate, without using any mask, a 30 nm thick SAO epitaxial sacrifice layer is first grown at 650℃ and 10 Pa oxygen pressure, and then a 50 nm thick SRO epitaxial functional layer is grown at 700℃ and 10 Pa oxygen pressure.

[0064] Step two: Try to perform standard photolithography patterning on the grown SRO / SAO / STO sample. After spin coating photoresist on the SRO surface, pre-baking and exposure are performed.

[0065] Step three: In the developing step, the sample is immersed in a developing solution (such as TMAH-based alkaline solution). During the developing process, the developing solution and the deionized water used in the subsequent cleaning step inevitably penetrate from the edge of the sample and directly contact the SAO sacrifice layer at the bottom.

[0066] Results: The SAO sacrifice layer reacts and dissolves rapidly after being exposed to water, causing the SRO functional film above it to be wrinkled, cracked and peeled off in a large area and uncontrollably and randomly before the patterning is completed. Finally, the functional film after patterning cannot be obtained, and the subsequent transfer step cannot be performed.

[0067] Conclusion: The results of the comparative example clearly prove that for the system using a water-soluble sacrifice layer, the existing "epitaxy first and patterning later" technical path has an insurmountable fundamental process incompatibility problem. The present application perfectly solves this problem through the innovative "patterning hard mask first and selective epitaxy later" strategy, highlighting the significant progress and practical value of the present application.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0069] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a patterned epitaxial heterostructure, characterized in that, Includes the following steps: 1) Forming a patterned hard mask layer on a single-crystal substrate; 2) A heterostructure is epitaxially deposited at high temperature on the surface of a hard mask patterned on the substrate. The heterostructure is selectively grown in the substrate window region exposed by the hard mask. The heterostructure includes an epitaxial sacrificial layer and an epitaxial functional layer grown sequentially. 3) Remove the patterned hard mask and then peel off the heterostructure material grown on top of the hard mask; 4) By selectively etching the epitaxial sacrificial layer, the patterned epitaxial functional layer carried by the sacrificial layer is stripped and released from the substrate.

2. The method for preparing a patterned epitaxial heterostructure according to claim 1, characterized in that, The hard mask layer has a multi-layer structure, including a metal sacrificial layer stacked sequentially for final wet stripping, a diffusion barrier layer to prevent inter-layer atomic interdiffusion at high temperatures, and a high-temperature rigid layer to protect the underlying structure and define the pattern.

3. The method for preparing a patterned epitaxial heterostructure according to claim 2, characterized in that, The metal sacrificial layer is made of aluminum, the diffusion barrier layer is made of tungsten, titanium nitride, tantalum nitride or a combination thereof, and the high-temperature rigid layer is made of nickel, platinum or iridium.

4. The method for preparing a patterned epitaxial heterostructure according to claim 1, characterized in that, Before step 2) high-temperature epitaxial deposition, an in-situ interface activation process is also included in the vacuum chamber of the deposition equipment to remove surface contaminants in the substrate window area exposed by the hard mask and activate the surface in preparation for the subsequent epitaxial sacrificial layer.

5. The method for preparing a patterned epitaxial heterostructure according to claim 4, characterized in that, In-situ interface activation treatment is performed using oxygen plasma treatment or low-energy argon ion beam treatment.

6. The method for preparing a patterned epitaxial heterostructure according to claim 1, characterized in that, In step 2), the high temperature range is 400℃ to 700℃.

7. The method for preparing a patterned epitaxial heterostructure according to claim 1, characterized in that, The epitaxial sacrificial layer is water-soluble Sr3Al2O6.

8. The method for preparing a patterned epitaxial heterostructure according to claim 1, characterized in that, The selective corrosion in step 4) is carried out in deionized water; The steps for removing a patterned hard mask include selectively eroding a metal sacrificial layer laterally using a strong alkaline solution, thereby stripping away the diffusion barrier layer, high-temperature rigid layer, and heterostructure covering it.

9. The method for preparing a patterned epitaxial heterostructure according to claim 1, characterized in that, Before step 4), a polymer support layer is spin-coated onto the sample surface to fix the relative position of the patterned epitaxial functional layer and provide mechanical support during peeling and transfer; wherein, after spin-coating the polymer support layer, a soft baking process is included, and the baking temperature is lower than the glass transition temperature of the polymer support layer, which is 80°C to 100°C.

10. A patterned epitaxial heterostructure, characterized in that, It is prepared by any one of the preparation methods according to claims 1 to 9.

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