A self-supporting thin film transfer method based on constructing a gas directional escape channel

Abstract

The application belongs to the technical field of semiconductor materials, and relates to a self-supporting film transfer method based on constructing a gas directional escape channel. The self-supporting film transfer method based on constructing a gas directional escape channel comprises the following steps: sequentially forming a sacrificial layer and a target film on the surface of an initial substrate; forming a support layer on the surface of the target film, the support layer and the target film are coincident in the planar projection direction at least two edges in the planar direction, so as to form a gas escape channel connected to the outside during the process of attaching the target substrate; dissolving the sacrificial layer, so that the target film is released from the initial substrate under the support of the support layer; transferring the released structure to the target substrate; and removing the support layer to obtain a target film / target substrate structure. The method improves the integrity of the target film transferred to the target substrate, and realizes large-area transfer of the target film.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor materials technology, specifically, it relates to a self-supporting thin film transfer method based on constructing a gas-directed escape channel. Background Technology

[0002] Perovskite oxides possess novel physical properties due to the similar energy scales and tight coupling of their degrees of freedom, such as lattice, spin, orbital, and charge. Perovskite oxide thin films and related structures offer unprecedented opportunities for exploring emerging ferroelectric properties and developing novel applications. However, several important scientific questions remain to be addressed in fundamental science and electronic device applications. First, because the strain state is fixed by the substrate lattice, its tunability is discrete and limited, fundamentally restricting the exploration and manipulation of emerging ferroelectric or magnetic properties in perovskite oxide thin films and heterostructures. Second, epitaxial ferroelectric oxides cannot exist independently of the substrate and typically lack flexibility, making them prone to brittle deformation. This further limits their applications in semiconductor device integration, van der Waals heterostructure integration, and wearable electronics. Therefore, developing a transfer method to improve the integrity of self-supporting oxide thin films is crucial for exploring the potential applications of oxide thin films in electronic devices.

[0003] The development of self-supporting thin films has provided a new solution to this problem. By introducing a selectively etchable or soluble sacrificial layer between the self-supporting film and the growth substrate, the epitaxial oxide film can be released as a whole while maintaining high crystal quality, and further transferred to metals, semiconductors, two-dimensional materials, flexible substrates, and silicon-based platforms. Therefore, the transfer technology of self-supporting thin films has important application value in the field of electronic devices and has been applied to the fabrication of ferroelectric tunnel junctions and ferroelectric field-effect transistors. For such applications, the integrity of the film after transfer is directly related to the stable realization of subsequent device performance. If cracks or damage occur in the film during the transfer process, the yield and performance of the device will be significantly reduced. Currently, the transfer methods of self-supporting thin films can generally be divided into two categories: direct transfer and two-step transfer. Direct transfer refers to directly transferring the target film onto the target substrate after dissolving the sacrificial layer. In this operation, the target film is usually inverted on the target substrate, fixed by a fixture, and then the sacrificial layer is dissolved to complete the transfer. However, since the fixture alone cannot perfectly bond the film to the substrate, solution seeps between the film and the substrate during the dissolution of the sacrificial layer. The self-supporting film, lacking support after the sacrificial layer dissolves, is easily damaged by the surface tension of the solution. Therefore, the success rate of transferring self-supporting films using this method is low, and the resulting films are not entirely intact.

[0004] Two-step transfer involves pre-introducing one or more support layers on the surface of the film to be transferred. After the sacrificial layer dissolves, the film is transferred to the target substrate through the support layer, and then the support layer is removed to complete the transfer. Compared with direct transfer, two-step transfer typically has a higher transfer success rate and better film integrity because the support layer provides mechanical support for the film during the release and transfer of the self-supporting film. The literature [Lu D, Baek DJ, Hong SS, Synthesis of freestanding single-crystal perovskite films and heterostructures by etching of sacrificial water-soluble layers[J]. Nature Materials, 2016, 15(12): 1255-1260.] discloses obtaining self-supporting single-crystal perovskite films and heterostructures by etching a water-soluble sacrificial layer. First, water-soluble Sr3Al2O6 (SAO) is epitaxially grown on a perovskite substrate, and then the film and heterostructure are grown in situ on it. By etching away the SAO layer in water, millimeter-sized single-crystal films can be obtained. Release of the self-supporting film: A flat PDMS sheet was prepared by spreading a polydimethylsiloxane (PDMS) layer with a thickness of approximately 0.1 mm onto a clean silicon wafer. An oxide heterostructure surface was then attached to the PDMS surface. This structure was immersed in filtered deionized water at room temperature to dissolve the SAO layer. To transfer the self-supporting oxide film to other substrates (such as silicon), the sample was attached to a commercial screen protector (silicone-coated polyethylene terephthalate film) and released in the same manner. After etching in water, a support layer with the self-supporting film was placed on the silicon wafer. The support layer was detached by heating at 70 °C for 10 minutes, leaving the film on the silicon wafer. The aforementioned existing technology still has shortcomings: When using this method, the area of ​​the silicone coating needs to be larger than the self-supporting film and completely cover it. If the film is located in the middle of the silicone coating, because the silicone coating usually has greater van der Waals forces and a faster adsorption rate than the film, it is easy for the silicone coating to adhere to the target substrate before the film has made sufficient contact with the target substrate. In this case, if there is residual air at the interface, the air will be squeezed and sealed between the film and the target substrate, forming bubbles that are difficult to expel. Once bubbles form, a uniform and continuous van der Waals contact interface cannot be formed between the film and the target substrate, resulting in insufficient actual contact area in some areas. When the silicone coating is removed subsequently, the ineffectively adhered film area is prone to cracking and gaps, leading to a decrease in overall integrity.

[0005] Therefore, there is an urgent need to develop a transfer method for self-supporting thin films to improve their integrity. Summary of the Invention

[0006] 1. The problem to be solved To address the technical problem in existing thin film transfer technologies that employ a two-step transfer method, although a support layer can provide mechanical support during the transfer process, the support layer adsorbs onto the target substrate before the thin film, easily trapping residual air between the thin film and the substrate and forming bubbles, thus severely affecting the integrity of the transferred thin film, this application provides a self-supporting thin film transfer method based on constructing directional gas escape channels. This method improves the integrity of the target thin film transferred to the target substrate and enables large-area transfer of the target thin film.

[0007] 2. Technical Solution To achieve the above objectives, the provided technical solution is as follows: A self-supporting thin film transfer method based on constructing a gas-directed escape channel includes the following steps: A sacrificial layer and a target thin film are sequentially formed on the surface of an initial substrate. A support layer is formed on the surface of the target thin film, wherein at least two edges of the support layer and the target thin film coincide in the plane projection direction, so as to form a gas escape channel communicating with the outside during the attachment process with the target substrate; Dissolve the sacrificial layer to release the target film from the initial substrate with the support of the support layer; The released structure is transferred to the target substrate; Remove the support layer to obtain the target thin film / target substrate structure.

[0008] The phrase "edges coincide in the plane projection direction" means that the boundary of the support layer and the boundary of the target film at least partially coincide or are collinear in the plane projection.

[0009] This application improves the integrity of target film transfer by aligning at least two edges of the support layer with the target film in the planar projection direction, which helps to expel air between the target film and the target substrate during transfer.

[0010] Furthermore, the at least two edges are two adjacent edges or two opposing edges.

[0011] Furthermore, the support layer has three edges that coincide with the edge of the target film in the planar projection direction.

[0012] Furthermore, the support layer comprises at least one layer, the support layer comprising polydimethylsiloxane.

[0013] Polydimethylsiloxane (PDMS) has strong adhesion at room temperature. As a support layer, it can provide mechanical support for the film while bonding the target film to the target substrate.

[0014] Preferably, the support layer further includes polymethyl methacrylate.

[0015] Furthermore, the support layer includes a first support layer and a second support layer, wherein the first support layer is disposed on the surface of the target film, and the second support layer is disposed on the first support layer.

[0016] Both support layers can provide mechanical support for the target thin film. The first support layer can isolate the target thin film from the second support layer, which is prone to residual contamination. The second support layer can serve as a carrier for thin film transfer and, due to its adhesiveness, can fix the thin film onto the target substrate.

[0017] Preferably, the first support layer is polymethyl methacrylate; the second support layer is polydimethylsiloxane.

[0018] Polymethyl methacrylate (PMMA) can be dissolved in a variety of organic solvents such as acetone, chloroform, and N-methylpyrrolidone. Therefore, in order to obtain a self-supporting film with a cleaner surface, a combination of PDMS / PMMA is usually selected as the support layer. PMMA plays a role in isolating contaminants during the preparation process to protect the cleanliness of the film.

[0019] Preferably, the specific operation for forming the first support layer on the surface of the target film is as follows: spin-coating the PMMA at 400 r / min to 800 r / min, then spin-coating at 800 r / min to 1200 r / min, and letting it stand for 5 to 10 minutes.

[0020] Preferably, the thickness of the second support layer is 200 μm to 500 μm.

[0021] Furthermore, the target thin film is a perovskite oxide self-supporting thin film; the perovskite oxide self-supporting thin film is selected from any one of STO, PTO, BTO or BFO.

[0022] Preferably, the thickness of the target thin film is 4 nm to 25 nm.

[0023] Furthermore, the sacrificial layer is a water-soluble oxide layer.

[0024] Preferably, the sacrificial layer is a SAO layer.

[0025] Preferably, the thickness of the SAO layer is 6 nm to 20 nm.

[0026] Furthermore, the sacrificial layer is dissolved by deionized water.

[0027] Preferably, the sacrificial layer dissolves in 6 h to 12 h.

[0028] Furthermore, the first support layer is removed by dissolving it with an organic solvent selected from acetone, chloroform, or N-methylpyrrolidone.

[0029] Preferably, the dissolution time of the first support layer is 1 h to 3 h.

[0030] Furthermore, the target substrate is selected from any one of silicon wafers, metal electrodes, or mica sheets.

[0031] 3. Beneficial effects Compared with existing known technologies, the technical solution provided by this invention has the following beneficial effects: This invention discloses a self-supporting thin film transfer method based on constructing a gas-directed escape channel. The method involves sequentially forming a sacrificial layer and a target thin film on the surface of an initial substrate; forming a support layer on the surface of the target thin film, wherein at least two edges of the support layer and the target thin film coincide in the planar projection direction to form a gas escape channel communicating with the outside during attachment to the target substrate; dissolving the sacrificial layer to release the target thin film from the initial substrate under the support of the support layer; transferring the released structure to the target substrate; and removing the support layer to obtain the target thin film / target substrate structure. During the attachment of the released structure to the target substrate, because the support layer PDMS typically has greater van der Waals forces and a faster adsorption rate than the self-supporting thin film, it is easy for PDMS to adhere to the target substrate before the thin film has made sufficient contact with it. In this case, if residual air exists at the interface, the air will be squeezed and trapped between the thin film and the target substrate, forming bubbles that are difficult to expel. Once air bubbles form, they prevent the formation of a uniform and continuous van der Waals interface between the film and the target substrate, resulting in insufficient actual contact area in local areas. During subsequent PDMS removal, the ineffectively attached film areas are prone to cracking, gaps, or even a decrease in overall integrity. This application aligns the support layer with at least two edges of the target film in the planar direction, which helps to eliminate residual air between the target film and the target substrate, improves the integrity of the target film transfer, and enables large-area, high-integrity transfer of self-supporting films.

[0032] This application significantly improves the film transfer integrity by using a simple boundary alignment method without adding additional material layers or complex processes, increasing the film integrity from 6.9% (Comparative Example 2) to 89.5% (Example 1). Attached Figure Description

[0033] Figure 1This is a schematic diagram of the transfer method for the self-supporting thin film in Example 1; Figure 2 This is a schematic diagram showing the relative positions of the PMMA / target film and PDMS in Example 1; Figure 3 This is a light microscope image of the self-supporting thin film transfer result in Example 1; Figure 4 This is a schematic diagram showing the relative positions of the PMMA / target film and PDMS in Example 2; Figure 5 This is a light microscope image of the self-supporting thin film transfer result in Example 2; Figure 6 This is a schematic diagram showing the relative positions of the PMMA / target film and PDMS in Example 3; Figure 7 This is a light microscope image of the self-supporting thin film transfer result in Example 3; Figure 8 This is a schematic diagram showing the relative positions of the PMMA / target film and PDMS in Comparative Example 1. Figure 9 The image shows the optical micrograph of the self-supporting thin film transfer result in Comparative Example 1. Figure 10 This is a schematic diagram showing the relative positions of the PMMA / target film and PDMS in Comparative Example 2; Figure 11 This is a schematic diagram showing the appearance of bubbles between the target thin film and the target substrate during the transfer process in Comparative Example 2. Figure 12 The image shows the optical micrograph of the self-supporting thin film transfer result in Comparative Example 2. Figure 13 This is a schematic diagram of the transfer method for the self-supporting thin film in Comparative Example 2. Explanation of the labels in the diagram: 201, Target thin film; 202, PMMA; 203, PDMS; 204, Target substrate. Detailed Implementation

[0034] To further understand the content of this invention, the invention will be described in detail with reference to the embodiments.

[0035] The present application will be further described below with reference to specific embodiments.

[0036] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0038] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0039] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable. As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0040] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the values ​​and ranges described above. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0041] The names, chemical formulas, and English abbreviations of the materials used in the examples are shown in the table below: Table 1 Material Names, Chemical Formulas, and Abbreviations

[0042] A sacrificial layer is deposited on an initial substrate using molecular beam epitaxy (MBE) to obtain a sacrificial layer / initial substrate. Then, a target thin film is deposited on the sacrificial layer using MBE to obtain a target thin film / sacrificial layer / initial substrate. This is an existing technology. The target thin film is a self-supporting thin film.

[0043] The second support layer used in this embodiment is PDMS, a commercially available solid elastic film with a thickness of 300 μm; the first support layer is PMMA, a commercially available spin-coating solution, designated 950K A4, where 950K indicates the average molecular weight of PMMA is 950K, A indicates that the solvent of the PMMA solution is anisole, and 4 indicates the concentration of the solution is 4%. The target substrate for the transfer is a commercially available silicon wafer with an oxide layer thickness of 285 nm.

[0044] Example 1 This embodiment of a self-supporting thin film transfer method based on constructing a gas-directed escape channel includes the following steps: S1. A sacrificial layer and a target thin film are sequentially formed on the surface of an initial substrate; the initial substrate is STO, the sacrificial layer is SAO, and the target thin film is STO, i.e., an STO / SAO / STO substrate structure.

[0045] The transfer technique using water-soluble oxide SAO as a sacrificial layer is applicable to various perovskite oxides because SAO has a lattice constant that matches that of perovskite films. For example, the lattice constant of cubic SAO is close to four times that of SrTiO3 (STO).

[0046] The target film for transfer is a 4.5 nm thick STO with a diameter of 2.5 mm × 2.5 mm.

[0047] S2. Form a first support layer on the surface of the target film. Use a pipette to draw PMMA solution and drop it onto the STO surface. Spin coat at 600 r / min for 10 s, then spin coat at 1000 r / min for 45 s. After that, let it stand for 5 min to wait for the anisole to evaporate and the PMMA to solidify. Repeat the spin coating twice to obtain the PMMA / STO / SAO / STO substrate structure.

[0048] S3. Use a cotton swab dipped in acetone to wipe around the PMMA / STO / SAO / STO substrate structure to remove any excess PMMA and prevent it from affecting the dissolution of SAO.

[0049] S4. A second support layer is provided on the first support layer, such that the second support layer is aligned with at least two edges of the target film in the planar direction, so as to form a gas escape channel communicating with the outside during the attachment process with the target substrate. "Edge alignment" means that the boundary of the support layer and the boundary of the target film are at least partially coincident or collinear in the planar projection; Cut the PDMS to a suitable size and adhere it to the PMMA surface. The PDMS thickness is 300 μm. When adhering, use... Figure 2The two adjacent edges of PDMS are aligned with the edges of PMMA, that is, the edges of the target thin film STO are aligned with the two adjacent edges of PDMS, to obtain a PDMS / PMMA / STO / SAO / STO substrate structure. Figure 2 The “202 / 201” indicates “PMMA / target film”, meaning that the PMMA and the target film are completely overlapped.

[0050] S5. Dissolve the sacrificial layer to release the target film from the initial substrate under the support of the first and second support layers; The PDMS / PMMA / STO / SAO / STO substrate structure was placed in deionized water and left to stand for 10 h until the SAO layer was fully dissolved. The STO substrate was then separated from the target film and removed to obtain the PDMS / PMMA / STO structure. The surface was dried with nitrogen gas to remove any remaining deionized water.

[0051] S6. Transfer the released structure, namely the PDMS / PMMA / STO structure, onto the target substrate silicon wafer. Expel the residual air through the gap between the two adjacent edges reserved in step S4, so that the STO and the silicon wafer can be fully bonded together to obtain the PDMS / PMMA / STO / silicon wafer structure.

[0052] S7. Remove the first support layer, place the PDMS / PMMA / STO / silicon wafer structure in acetone, let it stand for 2 hours until PMMA dissolves, PDMS separates from the target thin film STO, take it out, and obtain the STO / silicon wafer structure, i.e. the target thin film / target substrate structure, clean it with isopropanol and deionized water, and spin dry the surface moisture.

[0053] A schematic flowchart of the self-supporting thin film transfer method in this embodiment is shown below. Figure 1 As shown, the two adjacent edges of the second support layer PDMS film are aligned with the edge of the target film. Even if there is residual air, it will not be sealed inside and unable to escape, which facilitates the air expulsion when bonding with the target substrate later.

[0054] Example 2 This embodiment of the self-supporting thin film transfer method based on constructing a gas-directed escape channel is basically the same as that in Embodiment 1, except that... In step S4, with Figure 4 The two opposite edges of PDMS are aligned with the edges of PMMA, that is, the edges of the target thin film STO are aligned with the two opposite edges of PDMS, to obtain a PDMS / PMMA / STO / SAO / STO substrate structure.

[0055] This embodiment of a self-supporting thin film transfer method based on constructing a gas directional escape channel adopts another alignment method, aligning the two opposite edges of the second support layer PDMS film with the edge of the target film. Even if there is residual air, it will not be sealed inside and unable to escape, which facilitates the air expulsion during subsequent bonding with the target substrate.

[0056] Example 3 This embodiment of the self-supporting thin film transfer method based on constructing a gas-directed escape channel is basically the same as that in Embodiment 1, except that... In step S4, with Figure 6 The three edges of PDMS are aligned with the edges of PMMA, that is, the edges of the target thin film STO are aligned with the three edges of PDMS, to obtain a PDMS / PMMA / STO / SAO / STO substrate structure, which facilitates subsequent air venting.

[0057] This embodiment of a self-supporting thin film transfer method based on constructing a gas directional escape channel adopts a different alignment method, aligning the three edges of the second support layer PDMS film with the edge of the target film. Even if there is residual air, it will not be sealed inside and unable to escape, which facilitates the air expulsion during subsequent bonding with the target substrate.

[0058] As shown in Examples 1-3, all three methods can effectively remove air between the target STO thin film and the silicon wafer interface. The optical micrographs of the self-supporting thin film transfer results are shown below. Figure 3 , Figure 5 and Figure 7 During the transfer process, after the thin film is transferred onto the target substrate, due to optical interference, the area with the thin film and the target substrate will exhibit different colors. Specifically, in Figure 3 , Figure 5 and Figure 7In the image, the light-colored area (pink) represents the target substrate silicon wafer, and the dark-colored area (purple) represents the target thin film STO. The film color is related to its thickness; in this example, the STO thickness is 4.5 nm, therefore the target thin film STO appears purple. By distinguishing the color in the optical micrograph, it is determined whether a region is an STO thin film or a silicon wafer. The area of ​​the STO thin film in the optical micrograph is obtained, and the actual area of ​​the STO thin film transferred using the methods in Examples 1, 2, and 3 is calculated using a scale bar. The specific methods are as follows: The area of ​​the thin film is quantitatively analyzed using image processing methods. First, the image recognition function of artificial intelligence (such as ChatGPT) is used to accurately calibrate the pixel length of the scale bar in the optical micrograph. Based on the actual length of the scale bar (500 μm), the actual physical size (μm / pixel) and area (μm² / pixel) corresponding to each pixel in the image are calculated. Subsequently, the thin film region (dark part) in the image is identified and segmented at the pixel level, and the total number of pixels is counted. Finally, the total number of pixels is multiplied by the actual physical area of ​​a single pixel to obtain the actual area of ​​the thin film, i.e., the transferred area. The formula for calculating the integrity of a self-supporting thin film is as follows: The integrity of a self-supporting membrane = (area after transfer / area before transfer) × 100%.

[0059] The calculated integrity of the self-supporting films in Examples 1, 2, and 3 were 89.5%, 79.9%, and 68.3%, respectively.

[0060] In other embodiments, the target thin film may be selected from any one of PTO, BTO or BFO, and the self-supporting thin film transfer method of this application is applicable to the transfer of various perovskite self-supporting thin films.

[0061] Comparative Example 1 The method for transferring a self-supporting thin film in this comparative example is basically the same as in Example 1, except that... The target thin film is STO with a thickness of 10 nm.

[0062] In step S4, with Figure 8 The method involves aligning one edge of PDMS with the edge of PMMA, i.e., aligning the edge of the target thin film STO with one edge of PDMS, to obtain a PDMS / PMMA / STO / SAO / STO substrate structure.

[0063] The optical micrographs of the thin film transfer results in this comparative example are shown below. Figure 9As shown, the light-colored area (pink) is the target substrate silicon wafer, and the dark-colored area (blue) is the target thin film STO. The film color is related to the thickness. The STO thickness used in this comparative example is 10 nm, so the target thin film STO appears blue. According to the optical micrograph and the integrity calculation formula, the integrity of the transferred film is 41.3%. Since the PDMS and the target film are aligned with only one edge, the effect of bubble removal is weakened, and locally sealed residual bubbles are formed between the target film and the target substrate. When the PDMS is removed later, the ineffectively attached film area is prone to breakage, resulting in a low integrity of the transferred target film.

[0064] Comparative Example 2 The method for transferring a self-supporting thin film in this comparative example is basically the same as in Example 1, except that... The target thin film is PTO with a thickness of 25 nm.

[0065] In step S4, with Figure 10 The PMMA is placed in the center of PDMS without edge alignment, that is, the target thin film STO and PDMS are not edge aligned, resulting in a PDMS / PMMA / STO / SAO / STO substrate structure.

[0066] The flowchart of the self-supporting thin film transfer method in this comparative example is shown below. Figure 13 As shown, because the PTO film is located at the center of the PDMS and no channel is reserved for air exhaust, bubbles (such as...) appear between the PTO film and the target substrate silicon wafer during the transfer process of the self-supporting film in this comparative example. Figure 11 As shown in the image, after dissolving PMMA with acetone, the PTO film lost its support and broke apart, resulting in a limited area of ​​PTO film transferred onto the silicon wafer. The optical micrograph of the film transfer result is shown below. Figure 12 As shown, the light-colored area (pink) is the target substrate silicon wafer, and the dark-colored area (blue) is the target thin film PTO. The film color is related to the thickness. The PTO thickness used in this comparative example is 25 nm, so the target thin film PTO appears blue. According to the optical micrograph and the integrity calculation formula, the integrity of the transferred film is 6.9%.

[0067] In summary, the essence of the edge alignment described in this application lies in retaining at least two unclosed boundary regions during the attachment process between the target film and the target substrate, thereby forming gas escape channels connecting to the outside. During the transfer process, since the second support layer preferentially attaches to the target substrate, if the target film and the second support layer completely cover each other in the planar direction, the interfacial gas is easily trapped between the target film and the target substrate, forming bubbles. This application, by partially aligning the edges of the second support layer and the target film in the planar direction, forms open boundaries during the attachment process, providing escape channels for interfacial gas, avoiding gas closure, and thus significantly improving the transfer integrity of the target film.

[0068] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, improvements, and substitutions without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for transferring a self-supporting thin film based on constructing a gas-directed escape channel, characterized in that, Includes the following steps: A sacrificial layer and a target thin film are sequentially formed on the surface of an initial substrate. A support layer is formed on the surface of the target thin film, wherein at least two edges of the support layer and the target thin film coincide in the plane projection direction, so as to form a gas escape channel communicating with the outside during the attachment process with the target substrate; Dissolve the sacrificial layer to release the target film from the initial substrate with the support of the support layer; The released structure is transferred to the target substrate; Remove the support layer to obtain the target thin film / target substrate structure.

2. The self-supporting thin film transfer method based on constructing a gas-directed escape channel according to claim 1, characterized in that, The at least two edges are either adjacent edges or opposite edges.

3. The self-supporting thin film transfer method based on constructing a gas-directed escape channel according to claim 1, characterized in that, The support layer has three edges that coincide with the edges of the target film in the planar projection direction.

4. The self-supporting thin film transfer method based on constructing a gas-directed escape channel according to any one of claims 1-3, characterized in that, The support layer comprises at least one layer, and the support layer comprises polydimethylsiloxane.

5. The self-supporting thin film transfer method based on constructing a gas-directed escape channel according to claim 4, characterized in that, The support layer includes a first support layer and a second support layer, wherein the first support layer is disposed on the surface of the target film and the second support layer is disposed on the first support layer.

6. The self-supporting thin film transfer method based on constructing a gas-directed escape channel according to claim 1, characterized in that, The target thin film is a perovskite oxide self-supporting thin film; the perovskite oxide self-supporting thin film is selected from any one of SrTiO3, PbTiO3, BaTiO3 or BiFeO3.

7. The self-supporting thin film transfer method based on constructing a gas-directed escape channel according to claim 1, characterized in that, The sacrificial layer is a water-soluble oxide layer.

8. The self-supporting thin film transfer method based on constructing a gas-directed escape channel according to claim 1, characterized in that, The sacrificial layer is dissolved by deionized water.

9. The self-supporting thin film transfer method based on constructing a gas-directed escape channel according to claim 5, characterized in that, The first support layer is removed by dissolving it with an organic solvent, the organic solvent being selected from any one of acetone, chloroform, or N-methylpyrrolidone.

10. The self-supporting thin film transfer method based on constructing a gas-directed escape channel according to claim 1, characterized in that, The target substrate is selected from any one of silicon wafers, metal electrodes, or mica sheets.

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