COMPOSITE SUBSTRATE FOR EPITAXIAL GROWTH OF THIN FILM AND METHOD FOR MANUFACTURING SUCH SUBSTRATE - Patent application

Abstract

A method for manufacturing a composite substrate (10), comprising: providing a first crystalline layer (2); providing a carrier (5); and manufacturing the composite substrate (10) by depositing the first crystalline layer (2) on the carrier (5).

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates generally to the field of fabricating epitaxial crystalline layers on substrates. [Background technology]

[0002] Thin films grown epitaxially on substrates are widely used in technology. However, epitaxial growth typically requires depositing a film on a substrate that meets stringent requirements. For example, the crystal system and lattice constants of the substrate and film must match. Furthermore, the substrate and film must be chemically compatible. This often necessitates the use of expensive substrates. Substrates are typically single crystals cut from a crystal boule and then undergo orientation and polishing processes, making them expensive. If several films with different lattice constants need to be grown, a corresponding number of different substrates may be required. Furthermore, the material properties of the substrates may not match the requirements of the final device application. For example, only insulating substrates may be available for epitaxial growth of thin films, while device applications may require metallic or conductive substrates to carry the thin films.

[0003] To reduce costs, substrates are sometimes recycled by re-polishing after use, however, the recycling process is costly and cumbersome, and the number of re-polishing cycles is limited due to the reduction in substrate thickness inherent in each polishing step. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2020 / 0043790 (K. Lee et al., 'Systems and methods for fabricating semiconductor devices via remote epitaxy') [Non-patent literature]

[0005] [Non-Patent Document 1] K. Khang et al., 'Layer-by-layer assembly of two-dimensional materials into wafer-scale heterostructures', Nature 550, 229 (2017) [Non-patent document 2] H. Kim et al., 'Remote epitaxy', Nature Reviews 2:40 (2022) [Non-patent document 3] HS Kum et al. 'Heterogeneous integration of single-crystalline complex-oxide membranes', Nature 578, 75 (2020) [Non-patent document 4] D. Lu et al., 'Synthesis of freestanding single-crystal perovskite films and heterostructures by etch-ing of sacrificial water-soluble layers', Nat. Mater. 15, 1255 (2016) [Non-Patent Document 5] AJ Mannix et al., 'Robotic four-dimensional pixel assembly of van der Waals solids', Nature Nanotechnology 17, 361 (2022) [Non-patent document 6] Y. Shiohara et al., 'Overview of Materials and Power Applications of Coated Conductors Project', Japanese Journal of Applied Physics 51 (2012) 010007 Prior art Coated conductor technology

[0006] To solve this problem, an approach has been developed and used to grow 123-based high-Tc superconductors on polycrystalline Ni or steel tapes. In this so-called coated conductor technique, a buffer layer system is first deposited on the Ni or steel tape. Crystal orientation is induced in this buffer layer system, for example, by providing the Ni tape with an oriented surface structure, obtained by rolling the tape before deposition, or by irradiating the buffer layer at an oblique angle with an ion beam during growth (Non-Patent Document 6). As a result, the high-Tc superconductors grown on the buffer layer are polycrystalline with a few degrees of grain orientation. This method has the disadvantage that the films grown in this way are not of very good single-crystalline quality. Furthermore, the proposed procedure is specific to 123-based copper oxide films and Ni or steel tapes, and their development required many years and significant investments.

[0007] The following three techniques have not been used to solve the problem presented, but nevertheless comprise the state of the art that is relevant to the present invention in some aspects. 2D material stacking

[0008] So-called 2D materials, such as graphene and transition metal dichalcogenides, are composed of sheets only one or a few atomic layers thick (i.e., 2D layers). Stacks of such sheets are weakly held together only by van der Waals forces. A layer-by-layer assembly process is now commonly employed to sequentially build up such 2D layers through micromechanical peeling, transfer, orientation, and mechanical attachment. This process has been automated using robotic assembly (Non-Patent Document 5). This assembly process is frequently used to fabricate heterostructures of van der Waals materials (Non-Patent Document 1). Remote Epitaxy

[0009] In remote epitaxy (see Patent Literature 1, Non-Patent Literature 2), a first substrate is covered with a sheet of a so-called 2D material, such as graphene. On top of this sheet, another material is grown that is epitaxially aligned with the first substrate. Because the graphene layer can be peeled off from the substrate, the epitaxially grown layer is mechanically transferred as a free-standing film to a second substrate, such as a semiconductor chip, where the film is attached to achieve the desired functionality. Furthermore, additional 2D layers can be attached on top of the thus deposited 2D layer after mechanical transfer. To the best of the inventors' knowledge, no further films have been epitaxially grown on the 2D layer or film after transfer to a second substrate. Freestanding oxide film

[0010] To fabricate free-standing oxide films, a thin film of sacrificial release material is epitaxially grown on a first substrate. Then, multiple additional films are epitaxially deposited on this release layer. The material of the sacrificial release film is selected to be soluble in a solvent such as water or acid (Non-Patent Document 4). Therefore, by dissolving the release layer, the epitaxially grown additional films can be lifted off as free-standing films for mechanical transfer and attachment to a second substrate, where they can be used to achieve a desired function.

[0011] For these and other reasons, there is a need for the present disclosure. Summary of the Invention

[0012] The present disclosure can eliminate the need to use difficult-to-obtain or expensive single crystals as substrates for thin film growth. In particular, the present disclosure enables films to be epitaxially grown on substrates that, for example, due to material composition, lattice structure, or shape, are not themselves suitable to serve as substrates for epitaxial growth of such films.

[0013] One aspect of the present disclosure relates to a method of manufacturing a composite substrate, including providing a first crystalline layer, providing a carrier, and manufacturing the composite substrate by depositing the first crystalline layer on the carrier.

[0014] According to one embodiment of the method for manufacturing a composite substrate, the method further comprises epitaxially depositing a second crystalline layer on the first crystalline layer of the composite substrate, such that the first crystalline layer serves as a template layer for subsequent epitaxial growth of the second crystalline layer.

[0015] According to one embodiment of the method for manufacturing a composite substrate, providing the first crystalline layer includes providing a master substrate, depositing the first crystalline layer above the master substrate, and separating the first crystalline layer from the master substrate.

[0016] According to one embodiment of the method for manufacturing a composite substrate, the method further includes repeatedly reusing one and the same master substrate to manufacture a plurality of first crystalline layers, and subsequently manufacturing a plurality of composite substrates by depositing the plurality of first crystalline layers onto a corresponding plurality of carriers.

[0017] According to one embodiment of the method for manufacturing a composite substrate, the method further includes depositing a release layer on the master substrate and subsequently depositing a first crystalline layer on the release layer, and separating the stack from the master substrate includes removing the release layer.

[0018] According to one embodiment of the method for manufacturing a composite substrate, providing the first crystalline layer includes providing a laminate including a support layer and the first crystalline layer attached to the support layer, and manufacturing the composite substrate includes attaching the laminate onto a carrier.

[0019] According to another embodiment of the present invention, the laminate is cut, divided or severed into several pieces of smaller area and used to produce multiple composite substrates.

[0020] According to one embodiment of the method for manufacturing a composite substrate, the method includes disposing one or both of an adhesive layer and a blocking layer on a carrier, and subsequently depositing a first crystalline layer or stack onto the adhesive layer or the blocking layer.

[0021] A further aspect of the present disclosure relates to a composite substrate comprising a carrier and a first crystalline layer attached to the carrier, the first crystalline layer being of a different material than the carrier.

[0022] According to one embodiment of the composite substrate, the composite substrate further comprises an adhesive layer disposed between the carrier and the first crystalline layer.

[0023] According to one embodiment of the composite substrate, the composite substrate further comprises a blocking layer disposed between the carrier and the first crystalline layer and configured to reduce interdiffusion or electronic or magnetic interaction of atomic species between the carrier and the first crystalline layer.

[0024] According to one embodiment of the composite substrate, the composite substrate further comprises a second crystalline layer epitaxially grown on the first crystalline layer.

[0025] According to one embodiment of the composite substrate, the first crystalline layer and the second crystalline layer comprise the same or similar materials.

[0026] A further aspect of the present disclosure relates to a method of providing a crystalline layer, comprising providing a master substrate, depositing a crystalline layer above the master substrate, and separating the crystalline layer from the master substrate.

[0027] According to one embodiment of the method for providing a crystalline layer, the method further comprises depositing a release layer on the master substrate, subsequently depositing the crystalline layer on the release layer, and separating the crystalline layer from the master substrate by removing the release layer.

[0028] According to one embodiment of the method for providing a crystalline layer, the method further includes producing a stack by disposing a support layer on the crystalline layer, and separating the crystalline layer includes separating the stack from the master substrate.

[0029] According to one embodiment of the method for providing a crystal layer, arranging the crystal layer includes selecting a material for the crystal layer based on one or more of internal requirements, personal desires by a person, external requirements, and orders or requests from friends, business partners, or customers.

[0030] According to one embodiment of the method of providing a crystalline layer, the method further includes handing over or delivering the separated crystalline layer or the separated laminate to one or more of the person, entity, or customer who placed the order or request.

[0031] According to one embodiment of the method for providing a crystalline layer, depositing the exfoliation layer includes epitaxially depositing the exfoliation layer on the master substrate.

[0032] According to one embodiment of the method for providing a crystalline layer, depositing the crystalline layer comprises epitaxially depositing the crystalline layer on the master substrate or on the release layer.

[0033] According to one embodiment of the method for providing a crystalline layer, the thickness of the crystalline layer is in the range of 1 crystalline unit cell to 500 nm, 1 nm to 50 nm, or 5 nm to 50 nm. [Brief explanation of the drawings]

[0034] The accompanying drawings are included to provide a further understanding of the embodiments, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the embodiments. Other embodiments and many of the intended advantages of the embodiments will be readily appreciated as they become better understood by reference to the following detailed description.

[0035] The elements of the drawings are not necessarily to scale relative to each other, and like reference numerals indicate corresponding like parts. [Figure 1] 1A to 1C are schematic cross-sectional side views illustrating an example of a method for manufacturing a crystal layer according to one embodiment. [Figure 2] 10A to 10C are schematic cross-sectional side views showing an example of a method for manufacturing a composite substrate according to a further embodiment. [Figure 3] 3 is a schematic cross-sectional side view of a further example of a method for manufacturing a composite substrate according to FIG. 2, illustrating the production of a plurality of composite substrates by using a conventional substrate as a master substrate; [Figure 4] 3 is a schematic cross-sectional side view of a further example of a method for manufacturing a composite substrate according to FIG. 2, showing the production of a plurality of composite substrates by using the composite substrate as a master substrate; [Figure 5] FIG. 1 shows a photograph of an exemplary composite substrate. DETAILED DESCRIPTION OF THE INVENTION

[0036] In the following detailed description, references are made to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific embodiments in which the present disclosure may be practiced. In this regard, directional terms such as "top," "bottom," "front," "back," "leading," and "trailing" are used in reference to the orientation of the drawings being described. Because components of the embodiments can be positioned in many different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

[0037] It should be understood that the features of the various exemplary embodiments described herein may be combined with each other, unless otherwise stated.

[0038] As used herein, the terms "bonded," "attached," "connected," "coupled," and / or "electrically connected / electrically coupled" do not imply that elements or layers must be in direct contact with each other, but rather that there may be intervening elements or layers between the "bonded," "attached," "connected," "coupled," and / or "electrically connected / electrically coupled" elements, respectively. However, in accordance with the present disclosure, the above terms may optionally have the specific meaning that the elements or layers are in direct contact with each other, i.e., there are no intervening elements or layers between the "bonded," "attached," "connected," "coupled," and / or "electrically connected / electrically coupled" elements.

[0039] Furthermore, the terms "on," "over," or "above" when used with reference to a portion, element, or layer of material formed or located "on," "over," or "above" a surface may also be used herein to mean that the portion, element, or layer of material is located (e.g., placed, formed, deposited, etc.) "indirectly on" the intended surface, with one or more additional portions, elements, or layers disposed between the intended surface and the portion, element, or layer of material. However, the above terms when used with reference to a portion, element, or layer of material formed or located "on," "over," or "above" a surface may optionally have the specific meaning that the portion, element, or layer of material is located (e.g., placed, formed, deposited, etc.) "directly on," e.g., in direct contact with, the intended surface.

[0040] The following description will show in more detail how the problem of avoiding the use of expensive substrates is solved.

[0041] 1 is a schematic cross-sectional side view showing an example of a method for manufacturing a crystal layer according to one embodiment of the present disclosure, in which the crystal layer functions as a template layer in subsequent steps.

[0042] This solution is based on the understanding that only a surface layer, on the order of a few nanometers thick, of the substrate is actually required for epitaxial growth. Only this layer needs to be made of an expensive material with the desired lattice symmetry and lattice constant values. The remainder of the substrate, typically 0.5–1 mm thick, serves no function in the epitaxial growth process except as a suitable carrier for the surface layer. Therefore, 99.999% of the substrate's mass does not contribute to the epitaxial growth process, yet it accounts for the majority of the substrate's cost.

[0043] The present solution is further based on the realization that layers a few nm thick can be easily grown to high quality by standard epitaxial growth processes such as molecular beam epitaxy, pulsed laser deposition, or other known film deposition procedures.

[0044] It is therefore possible to produce a desired crystalline surface layer 2 by epitaxial deposition of a thin film on a selected substrate 1 ("master substrate" 1). According to the example shown in Figure 1, this thin film 2 is not deposited directly on this master substrate 1, but rather on a sacrificial release layer 3 that has been previously deposited on said master substrate 1.

[0045] Optionally, a support layer 4 can be attached to the crystal layer 2, thereby forming a laminate including the crystal layer 2 and the support layer 4. The support layer 4 can facilitate subsequent removal of the crystal layer 2 from the master substrate 1. However, the support layer 4 can be omitted depending on the properties of the crystal layer 2, particularly its thickness.

[0046] Later, to remove the crystalline layer 2, the sacrificial release layer 3 is removed and the crystalline layer 2 can be transferred to a carrier for manufacturing a composite substrate by a user as will be shown later in connection with FIG.

[0047] Furthermore, after the detachment of the crystalline layer 2, the master substrate 1 can be recycled by refurbishing its surface (indicated by the large arrow), for example by laser heating to a temperature that results in significant surface diffusion. Thus, the master substrate 1 is not consumed in the process; it can be stored and recycled, contributing to a reduction in the costs of the thin film growth process. However, it is of course also possible to refurbish the master substrate by chemical cleaning, etching, polishing, or similar processes.

[0048] According to one example, the master substrate 1 may consist of a single crystalline material, for example a 1 mm thick SrTiO3 single crystal with a <0001> orientation, or a 0.5 mm thick DyScO3 single crystal with a <0001> orientation. The master substrate may also be of bicrystalline or polycrystalline or amorphous compound so as to provide a bicrystalline or polycrystalline or amorphous template that can be subjected to the epitaxial growth of the respective films.

[0049] According to a further example, a composite substrate as produced according to FIG. 2 can also be used as a master substrate in further growth processes.

[0050] According to a further example, several templates may be deposited on a carrier substrate by lateral stitching. In this case, the carrier substrate can be very large, since its surface layer can consist of an array of stitched templates. The stitched patches can be intentionally oriented or patterned, for example with different in-plane orientations. The stitched patches can also be made of different materials or have different lattice structures.

[0051] By way of further example, ideally the crystal lattice symmetry and lattice constant of the master substrate is identical to the crystal lattice symmetry and lattice constant of the epitaxial film 8 that will subsequently be grown by the user. If the lattice constants are different, a release layer may be used to bridge the difference.

[0052] According to a further example, the template layer is grown to a thickness that exceeds the critical thickness for stress relief, which may result in different lattice constants at the top and bottom surfaces of the template layer, with the lattice constant at the top surface being more ideally suited for subsequent epitaxial growth of film 8 by the user.

[0053] According to an example, the material of the release layer 3 may be, for example, Sr3Al2O6, Sr2CaAl2O3, Sr 3-x Ca x It can be Al2O3 (=solid solution), a soluble manganite, or a nickelate. In the ideal case, the crystal lattice and lattice constants are identical or similar to those of the epitaxial film 2 grown by the user. The exfoliation layer 3 may be composed of a solid solution, in which case the lattice parameters can be adjusted by selecting the composition of the solid solution. If the lattice constant of the exfoliation layer 3 matches the lattice constant of the epitaxial film 8 grown by the user but does not match the lattice constant of the master substrate 1, the exfoliation layer 3 may be grown to a thickness exceeding its critical thickness so that the distortion of the mismatched lattice is compensated by a dislocation layer. If the material of the exfoliation layer 3 consists of a solid solution, its composition may be further varied during its growth to bridge the difference between the constants of the master substrate 1 and the crystal layer 8 epitaxially grown by the user. The exfoliation layer 3 may also be a van der Waals material that can be separated, for example, by exfoliation.

[0054] It should be noted in this respect that the use of the release layer 3 is also merely optional. For at least some materials, other processes are conceivable as alternatives to a release layer. The removal of the crystalline layer 2 from the master substrate 1 can in particular be achieved by peeling or by other release mechanisms, such as, for example, by implanting hydrogen into the sample.

[0055] According to a further example, at least one blocking layer 7 can be deposited on or above the master substrate 1. The function of the blocking layer 7 will be explained below. If a release layer 3 is used, the at least one blocking layer 7 is deposited on the release layer 3, followed by the deposition of the first crystalline layer (2) on or above the blocking layer 7.

[0056] According to one example, the material of the support layer 4 can be, for example, one or more of a polymer or a varnish. The material of the support layer 4 must be suitable for peeling so as to obtain a clean surface for the crystal layer 2. The support layer 4 may be adhered to the crystal layer 2 by an adhesive that can be subsequently removed by an appropriate gas atmosphere.

[0057] According to one example, the material of the crystalline layer 2 can be made of the material of a film that will later be epitaxially grown by the user, such as SrTiO3 or DyScO3. The crystalline layer 2 can have a thickness of 1 unit cell to 500 nm (depending on the material and application), preferably 5-50 nm. For example, it can be a 10 nm thick SrTiO3 film with a <0001> orientation or a 25 nm thick DyScO3 film with a <0001> orientation. The crystalline layer 2 may comprise any material that can be grown on the dissolvable exfoliation layer 3 in the crystalline structure desired for the user's epitaxial film 8 (preferably single crystal in most cases), for example as a perovskite, spinel, oxide, nitride, carbide, or 2D material.

[0058] According to one example, the crystalline layer 2 may differ in composition (e.g., doping) from the master substrate 1 or the carrier 5. The crystalline layer 2 may itself be multilayered or may carry a film for later use in the application. The crystalline layer 2 is grown epitaxially on the master substrate and is often grown as a single crystalline layer, although in some applications it may be preferable for the growth to be non-epitaxial, or for the crystalline layer 2 to have several crystals, or even a polycrystalline or amorphous structure.

[0059] Because the crystalline layer 2 is grown in a thin film deposition process, it may contain fewer impurities than a bulk single crystal of the same compound conventionally used as a substrate. When the master substrate 1 is fabricated using a process such as that presented above, the crystalline layer 2 may contain fewer defects (e.g., fewer dislocations) than a bulk single crystal of the same compound.

[0060] 2 is a schematic cross-sectional side view showing an example of a method for manufacturing a composite substrate according to a further embodiment. The hexagon in the lower left corner shows an example of a possible top view of the carrier, indicating that the carrier can have almost any cross-sectional shape.

[0061] As explained above in relation to Figure 1, by dissolving the release layer 3, the crystalline layer 2 can be removed from the master substrate 1 and transferred to a carrier material of choice ("carrier" 5). This carrier material does not have to meet the constraints for the epitaxial growth of the film 8. It can therefore be much less expensive or even further optimized compared to the master substrate 1.

[0062] The gist of the present invention is provided by the fact that the combination of the carrier and the template layer on its surface is called a "composite substrate" and can be handled and used like a conventional substrate. The resulting composite substrate may be used as a master substrate in further growth steps.

[0063] The present invention thus obviates the need to use expensive master substrates for epitaxial growth of thin films. Instead, one master substrate can be used to produce a large number of less expensive composite substrates, where only the top surface is optimized for epitaxial deposition. This allows for multiple epitaxial film depositions to be achieved by using epitaxial imprints of the master substrate's surface to serve as functional templates for the desired epitaxial growth and fixing these imprints as coatings to a suitable, inexpensive carrier. The present invention thus provides a method for providing a selected surface on a selected carrier for epitaxial growth.

[0064] 2, a laminate including a crystal layer 2 and a support layer 4 is attached to a carrier 5. As mentioned above, the support layer 4 is optional and may be omitted depending on the configuration, particularly the thickness of the crystal layer 2. Prior to attachment of the laminate, an adhesive layer 6 and a blocking layer 7 may be deposited on the carrier 5 or on the crystal layer 2.

[0065] The material of the carrier 5 can be an elemental or compound semiconductor, an oxide (e.g., sapphire), a nitride (e.g., BN), a carbide, diamond, glass, a polymer, a semiconductor die or chip or circuit, or an existing object to be coated (Ti parts for the human body, cables, steel rods, etc.). The material of the carrier 5 can be a material with advantageous properties for subsequent epitaxial growth (thermal stability, absorption of a heating laser beam, processability) or advantageous properties for the intended application, such as high or low thermal conductivity, high mechanical strength, elasticity (e.g., elasticity to allow reversal between concave and convex shapes), magnetic properties, electrical conductivity, ferroelectricity, piezoelectricity, superconductivity, low noise (low defect density, optimal dielectric properties), low RF loss angle. The carrier is, for example, an optical element such as a convex optical glass lens, on which further layers can be epitaxially grown as single crystalline materials to obtain desired properties (optical, mechanical, electronic, etc.) by template layer deposition.

[0066] The layer structure of the composite substrate, including the carrier, may be selected such that a local or global modification of the lattice constant of the template layer can be achieved, for example, by means of a piezoelectric layer. Such adaptation may be useful for locally or globally adjusting the surface of the template layer 2 to optimize the subsequent growth of layer 8.

[0067] With regard to lattice structure, the carrier 5 may have a different lattice structure than the film 8 to be grown. For example, it may be monocrystalline, polycrystalline, or amorphous, e.g., glass. The carrier 5 may have a different thermal expansion behavior than the template layer 2, with the template layer being in compressive or tensile strain at the growth temperature of the subsequent epitaxial structure.

[0068] In terms of architecture, the carrier 5 may itself comprise a heterostructure, or it may be structured, pre-patterned, provided with holes, channels, (buried) conductive lines, mechanical devices, electronic devices, chemical devices, etc.

[0069] In terms of shape, the carrier 5 can be larger (or smaller) than the crystalline layer 2 and may have complex shapes, such as planar hexagons (examples of which are shown in the bottom part of FIG. 2), irregularities (for mirrors, RF cavities, lens coatings, and for imparting stress or strain), surface ripples, arrays of surface protrusions, etc. The shape of the carrier can be actively adjusted, for example, by applying an electric field across a piezoelectric carrier. The surface of the carrier usually does not need to be as well polished as required for good epitaxial growth.

[0070] The carrier 5 and / or the crystalline layer 2 may be covered with a thin adhesive layer 6 that strengthens the bond between them. Induced by a heating process, the adhesive layer 6 may "solder" or "weld" the crystalline layer 2 and the carrier 5 together, e.g., by forming a eutectic solution. The adhesive layer may act as a diffusion or conduction path to conduct moisture or additional substances, such as gases or liquids, trapped between the carrier and the template layer during the manufacturing process to the environment, or may absorb these substances into the adhesive layer.

[0071] When using a sapphire substrate as the carrier 5, the adhesion layer 6 may comprise a 5 nm thick layer of amorphous SrTiO3 deposited on the sapphire substrate and heated to 600°C for 10 minutes to promote bonding with the SrTiO3 template that is then transferred.

[0072] In some applications, the carrier 5 may have undesirable effects on the crystalline layer 2 or the film being epitaxially grown. These effects may include atomic interdiffusion or electronic or magnetic interactions. A blocking layer 7 deposited between the carrier 5 and the crystalline layer 2 or on the surface of the crystalline layer 2 can be used to minimize these effects. The blocking layer 7 is selected to have low diffusivity for unwanted atomic species that may diffuse, to be conductive or superconducting, or to have high magnetic permeability to electromagnetically shield the film 8 being epitaxially grown from the carrier. As mentioned above, the blocking layer 7 can also be fabricated at an earlier stage.

[0073] One aspect of the present disclosure relates to a composite substrate. An example of such a composite substrate 10 is shown in the central portion of FIG. 2. The composite substrate 10 of FIG. 2 includes a carrier 5, an adhesive layer 6 disposed on the carrier 5, a blocking layer 7 disposed on the adhesive layer 6, and a crystal layer 2 (template) disposed on the blocking layer 7. The crystal layer 2 may cover the edges of the carrier 5. The order of the adhesive layer 6 and the blocking layer 7 may be reversed. As already mentioned, the adhesive layer 6 and the blocking layer 7 may also be omitted. The composite substrate 10 may be subjected to a surface treatment and / or a termination treatment, for example, by (laser) heating.

[0074] Figures 3 and 4 are schematic cross-sectional side views illustrating further examples of methods for manufacturing composite substrates in accordance with Figure 2. In both figures, the use of a single master substrate to manufacture many composite substrates without consuming or modifying the master substrate is shown.

[0075] FIG. 3 illustrates the fabrication of multiple composite substrates 10 by using a conventional substrate 1 as a master substrate 1 .

[0076] FIG. 4 illustrates the fabrication of multiple composite substrates 20 by using composite substrate 10 as a master substrate 10 .

[0077] The entire process as shown in FIGS. 1 and 2 may be performed by a single entity, such as a company, academic research institute, or the like. However, it should be noted at this point that the process may also be performed by at least two different entities. In particular, the method for manufacturing the crystalline layer shown and described in connection with FIG. 1 may be performed by a first entity, and the method for manufacturing the composite substrate shown and described in connection with FIG. 2 may be performed by a second entity different from the first entity. The first entity may perform the method of FIG. 1 , for example, by selecting the material for the crystalline layer 2 without external input, for example, based on internal requirements or a personal request by a person, or based on external requirements or an order or request from a friend, business partner, or customer. In particular, the second entity performing the method of FIG. 2 may act as a customer of the first entity, for example, by sending an order to the first entity to manufacture one or more crystalline layers 2 of a particular material and receiving the crystalline layers 2 for manufacturing the composite substrate 10. It is also possible that the second entity does not perform epitaxial growth of the crystalline layer 8, but instead hands over the manufactured composite substrate to a third entity that acts as a final processor of the delivered composite substrate 10.

[0078] Examples of film deposition techniques that can be used to grow release, template, support, adhesion, or blocking layers include thermal laser epitaxy, sputtering, MOCVD, pulsed laser deposition, or spin coating.

[0079] For the crystalline layer 2, the composition of the material system forming the solid solution compound can be selected to select the lattice parameter of the crystalline layer 2 to exactly match the desired value (in most cases, the lattice constant of the user-grown film in FIG. 2). The lattice parameter can be software-controlled by implementing a computer-controlled process (e.g., thermal laser epitaxy). The crystalline layer 2 can also be fabricated by remote epitaxy.

[0080] For the release layer 3, the release rate is an important parameter for mass production, and in the case of chemical dissolution of the release layer, a short dissolution time may be preferable. The properties of the release layer, such as the material, thickness, and microstructure, are important for a short dissolution time. For release by wet chemical etching, important control parameters for the dissolution time are, for example, the solvent composition, T, P, and pH value. For release by gas-phase etching, such as reactive ion etching, important control parameters are, for example, the gas-phase composition, T, and P. The crystalline layer 2 may be vacuum dried after release.

[0081] Further exfoliation and crystalline layers may be grown on the first exfoliation and crystalline layers.

[0082] The support layer 4 may be peeled off by, for example, heating, melting, or oxidation, for example, oxidation in plasma, or, if an adhesive is used, changing the atmosphere to peel off the adhesive.

[0083] The attachment of the crystalline layer 2 onto the carrier 5 can be performed, for example, in vacuum by in-situ heating to obtain a clean surface and / or can be performed, for example, using a heating process and / or an adhesive layer. The crystalline layer 2 can be attached with any desired orientation angle between the crystalline layer 2 and the carrier 5. The crystalline layer 2 can be attached onto the carrier 5 or onto a mechanically pre-stressed carrier (uniaxially or isotropically) at elevated or reduced temperatures to create an intentionally strained crystalline layer 2 at room temperature or at the deposition temperature of the subsequent layer.

[0084] If the carrier 5 is larger than the crystal layer 2, the crystal layer 2 may be attached at a desired position on the carrier 5. Multiple crystal layers 2 of different materials, shapes, etc. may be attached on one carrier by lateral separation, stitching, overlapping, or lamination.

[0085] Regarding the preparation of the composite substrate 10 for the growth of the epitaxial film 8, the surface of the composite substrate 10 can be annealed to remove defects and make it atomically flat by subjecting the composite substrate 10 to a thermal annealing process. This annealing process is preferably performed in situ, for example, by laser heating. For the SrTiO3 crystalline layer 2, an annealing process at 1300°C for 5 minutes may be selected. A similar annealing process may be performed to terminate the surface of the composite substrate 10 to include one well-defined atomic layer. TiO2 termination of the SrTiO3 crystalline layer 2 may be achieved by an annealing process at 1300°C for 5 minutes.

[0086] The master substrate 1 can be refurbished, for example, by laser heating with a CO2 laser to 1300°C for 10 minutes (preferred), by mechanical polishing (not preferred as polishing is a subtractive process), or by epitaxy, in particular homoepitaxy.

[0087] With regard to refurbishing a used composite substrate 10, the composite substrate 10 can be re-polished or simply reused by adding additional crystalline layers.

[0088] At least a portion of the process may be continuous (e.g., for the production of coated conductors), and may be parallelized for batch production of identical composite substrates or libraries of composite substrates with a range of properties (e.g., different carrier materials, carrier shapes, template materials), and may be capable of being performed in vacuum, air, liquid, or controlled atmosphere, and may be automated, robotized (e.g., mounting the film onto the carrier), and computer-controlled.

[0089] Composite substrates have favorable properties compared to flakes of crystalline layers. For example, they are more practical to handle. It is easier to controllably heat composite substrates. The film properties and composite substrate properties can be obtained with greater reproducibility than those of standard single crystal substrates, which vary with the growth process of the single crystal. Furthermore, the surface orientation (vicinal cut) is reproducible.

[0090] FIG. 5 shows a photograph of an exemplary composite substrate.

[0091] The carrier 5 is made of sapphire crystal. A 20 nm thick film is formed on the (0001) plane of the carrier 5. <100> A 24 nm thick La 0.67 Sr 0.33 MnO films were prepared by the user using pulsed laser deposition (700 °C, 2.3 J / cm in 0.1 mbar O). 2 The SrTiO3 template 2 was epitaxially grown by irradiation with 248 nm excimer laser light at 1 Hz with a fluence of 1000 nm. <100> Pulsed layer deposition (900℃, 10 -5 mbar O2, 0.8 J / cm 2 The Sr2CaAl2O6 exfoliation layer is used as the master substrate 1. <100> Pulsed layer deposition (825°C, 10 -5 mbar O2, 1.6 J / cm 2 The SrTiO3 layers were epitaxially grown to a thickness of 24 nm using a 248 nm excimer laser (irradiated at 1 Hz with a fluence of 100 Hz). The support layer used consisted of a polymer (PMMA) film approximately 600 nm thick that was spin-coated onto the template layer before peeling. Peeling of the stack from the SrTiO3 substrate was achieved by immersing the sample in distilled water heated to 80 °C for 24 h.

[0092] Further examples are described below. The carrier 5 is made of sapphire crystal. A 15 nm thick film is formed on the (0001) plane of the carrier 5. <100> A oriented DyScO template layer 2 is deposited on this composite substrate 10. A 24 nm thick BaTiO film 8 is deposited by the user using pulsed laser deposition (720 °C, 2.1 J / cm in 0.2 mbar O). 2 The DyScO3 template 2 can be epitaxially grown by irradiation with 248 nm excimer laser light at a fluence of 1000 Hz and 5 Hz. The DyScO3 template 2 is covered with a release layer and used as a master substrate 1. <100> Pulsed layer deposition (880℃, 10 -5 mbar O2, 1.0 J / cm 2 The Sr3Al2O6 exfoliation layer is grown epitaxially by irradiation with 248 nm excimer laser light at 1 Hz with a fluence of <100> Pulsed layer deposition (825°C, 10 -5 mbar O2, 1.6 J / cm 2 The SrTiO3 layers were epitaxially grown to a thickness of 24 nm using a 248 nm excimer laser (irradiated at 1 Hz with a fluence of 100 Hz). The support layer used consisted of a polymer (PMMA) film approximately 500 nm thick, spin-coated onto the template layer before delamination. Delamination of the layer from the SrTiO3 substrate was achieved by immersing the sample in distilled water heated to 80 °C for 24 hours.

[0093] In summary, the following applications of the present invention are conceivable, for example: - Production of novel substrates with novel surface properties or functions - Standard board replacement - Large area epitaxial coating, e.g. long, wide tapes, coated conductors - High quality epitaxial coatings for curved optical elements and resonators - Epitaxial growth of functional materials on CMOS chips - Complex devices that combine materials with different crystalline systems on a single chip If the carrier or template has a periodic structure, such as an array of grooves, the epitaxially grown film may have periodically modulated properties, for example due to strain effects. - To provide an amorphous organic material with a monocrystalline surface layer for further epitaxial growth.

[0094] Furthermore, the following extensions of the present invention are possible. - stacking of multiple crystalline layers with epitaxially grown and possibly structured films, 3D manufacturing - The films or heterostructures grown on the composite substrate do not necessarily have to be grown epitaxially. a) Template layers realizable by remote epitaxy, where the carrier / 2D layer / template stack system is unclear b) Epitaxially grown template layers (e.g., oxides) contain a much larger variety of compounds, many of which are chemically more robust and versatile than 2D materials such as graphene.

[0095] Furthermore, while a particular feature or aspect of one embodiment of the present disclosure may be disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of other implementations, as may be desirable and advantageous for any given or advantageous application. Furthermore, to the extent that "include," "have," "with," or other variations thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to "comprise." Furthermore, it should be understood that embodiments of the present disclosure may be implemented in discrete circuits, partially integrated circuits, or fully integrated circuits, or programming means. Furthermore, the term "exemplary" is merely illustrative and does not imply best or optimal. It should also be understood that features and / or elements shown herein are shown in specific dimensions relative to each other for simplicity and ease of understanding, and that actual dimensions may differ significantly from those shown herein.

[0096] While specific embodiments have been illustrated and described herein, those skilled in the art will recognize that various alternative and / or equivalent implementations may be substituted for the specific embodiments illustrated and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments described herein. Accordingly, it is intended that the present disclosure be limited only by the claims and equivalents thereof.

Claims

1. Providing a first crystalline layer (2); Providing a carrier (5); producing a composite substrate (10) by depositing said first crystalline layer (2) on said carrier (5); A method for manufacturing a composite substrate (10), comprising:

2. Providing the first crystalline layer (2) comprises: Providing a master substrate (1); depositing said first crystalline layer (2) on or above said master substrate (1); Separating the first crystalline layer (2) from the master substrate (1); Including, The method of claim 1.

3. repeatedly reusing one and the same master substrate (1) to manufacture a plurality of first crystalline layers (2), and subsequently depositing the plurality of first crystalline layers (2) onto a corresponding plurality of carriers (5), thereby manufacturing a plurality of composite substrates (10); The method of claim 2 further comprising:

4. depositing a release layer (3) on or above the master substrate (1) and subsequently depositing the first crystalline layer (2) on or above the release layer (3); further comprising Separating the first crystalline layer (2) from the master substrate (1) comprises removing the release layer (3) from the master substrate (1); The method according to claim 2 or 3.

5. depositing at least one blocking layer (7) on or above said master substrate (1); The method of any one of claims 1 to 4, further comprising:

6. depositing said at least one blocking layer (7) on said release layer (3), followed by depositing said first crystalline layer (2) on or above said at least one blocking layer (7); The method of claim 4 or 5, further comprising:

7. Providing the first crystalline layer (2) includes providing a laminate (2, 4) including a support layer (4) and the first crystalline layer (2) attached to the support layer (4); Manufacturing the composite substrate (10) comprises depositing the stack (2, 4) on the carrier (5). The method according to any one of claims 1 to 6.

8. Manufacturing the composite substrate (10) comprises disposing one or both of an adhesive layer (6) and a blocking layer (7) on the carrier (1), and subsequently depositing the first crystalline layer (2) or the stack (2, 4) on the adhesive layer (6) or the blocking layer (7). The method according to any one of claims 1 to 7.

9. epitaxially depositing a second crystalline layer (8) on the first crystalline layer (2) of the composite substrate (10); The method of any one of claims 1 to 8, further comprising:

10. Career (5) and a first crystalline layer (2) attached to the carrier (5), the material of the first crystalline layer (2) being different from the material of the carrier (5); A composite substrate (10) comprising:

11. an adhesive layer (6) disposed between the carrier (5) and the first crystal layer (2); The composite substrate (10) of claim 10, further comprising:

12. a blocking layer (7) disposed between the carrier (5) and the first crystalline layer (2) and configured to reduce interdiffusion or electronic or magnetic interaction of atomic species between the carrier (5) and the first crystalline layer (2); 12. The composite substrate (10) of claim 10 or 11, further comprising:

13. A second crystalline layer (8) epitaxially grown on the first crystalline layer (2). The composite substrate (10) of any one of claims 10 to 12, further comprising:

14. the first crystalline layer (2) and the second crystalline layer (8) comprise the same or structurally or chemically related materials; The composite substrate (10) of claim 13.

15. Providing a master substrate (1); Depositing a crystalline layer (2) on or above said master substrate (1); Separating the crystalline layer (2) from the master substrate (1); A method for providing a crystalline layer, comprising:

16. Depositing a release layer (3) on the master substrate (1) and subsequently depositing the crystal layer (2) on the release layer (3); Separating the crystalline layer (2) from the master substrate (1) by removing the release layer (3); 16. The method of claim 15, further comprising:

17. depositing at least one blocking layer (7) on or above said master substrate (1), 17. The method of claim 15 or 16, further comprising:

18. depositing said at least one blocking layer (7) on said release layer (3), followed by depositing said first crystalline layer (2) on or above said at least one blocking layer (7); 18. The method of claim 16 or 17, further comprising:

19. and further comprising disposing a support layer (4) on the crystal layer (2) to produce a laminate (2, 4), Separating the crystal layer (2) comprises separating the stack (2, 4) from the master substrate (1); The method according to any one of claims 15 to 18.

20. Arranging the crystal layer (2) includes selecting a material for the crystal layer (2) based on one or more of internal requirements, personal desires by a person, external requirements, and orders or requests from friends, business partners, or customers. The method according to any one of claims 15 to 19.

21. handing over or delivering the separated crystal layer (2) or the separated stack (2, 4) to one or more of the individuals, corporations, organizations, companies or customers who placed the order or request; 21. The method of claim 20, further comprising:

22. Depositing the release layer (3) comprises epitaxially depositing the release layer (3) on the master substrate (1); The method according to any one of claims 16 to 21.

23. Depositing the crystalline layer (2) comprises epitaxially depositing the crystalline layer (2) on the master substrate (1) or on the release layer (3); The method according to any one of claims 15 to 22.

24. The thickness of the crystalline layer (2) is in the range of 1 crystalline unit cell to 500 nm, 1 nm to 50 nm, or 5 nm to 50 nm; The method according to any one of claims 15 to 23.

25. The difference between the lattice constant projections of the release layer (3) and the crystal layer (2) is less than 10% or less than 5%; The method according to any one of claims 16 to 24.

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