Carrier stack for transferring two-dimensional (2D) material to target substrate, and method for transferring 2D material to target substrate
By combining rigid or semi-rigid carrier substrates with adhesive layers, the compatibility problem of 2D material transfer in semiconductor manufacturing is solved, achieving efficient and reliable material transfer and processing, suitable for mass production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BLACK SEMICONDUCTOR NETHERLANDS BV
- Filing Date
- 2024-07-05
- Publication Date
- 2026-04-24
AI Technical Summary
Existing technologies struggle to achieve high-throughput or high-volume manufacturing compatible 2D material transfer in semiconductor manufacturing. Commonly used tools are incompatible with the semiconductor industry, leading to decreased material quality and processing difficulties.
A combination of rigid or semi-rigid carrier substrates and adhesive layers is used to reliably transfer 2D materials from the growth substrate to the target substrate via thermal sliding or electrochemical methods, employing automated wafer bonding and debonding technologies.
It enables 2D material transfer compatible with high throughput in semiconductor manufacturing, ensuring material quality and processing efficiency, and is suitable for conventional bonding/debonding tools, supporting high-volume manufacturing.
Smart Images
Figure CN121925391A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a transfer carrier or carrier stack for transferring two-dimensional (2D) material to a target substrate, a method for producing the carrier stack, and a method for transferring 2D material from the carrier stack to a target substrate. The transfer carrier and associated method are compatible with high-volume manufacturing in the semiconductor industry. Background Technology
[0002] Two-dimensional (2D) materials are those that have a macroscopic dimension in two dimensions and a thickness of only one or a few atoms in a third dimension. Graphene is a well-known example of a 2D material that has recently attracted considerable scientific and technological interest. Other examples include graphene-based materials, graphene-containing materials, chemically modified graphene, hexagonal boron nitride (h-BN), and TMDC materials (such as MoS2, WS2, MoSe2, WSe2, etc.).
[0003] Such 2D materials have been observed to possess specific properties, such as those relating to electrical and / or chemical properties. These specific properties make 2D materials (such as graphene or graphene-containing materials or TMDC) highly attractive for a wide range of applications, including electronics, lasers, biosensors, photonic switches, light-emitting diodes (LEDs), infrared sensors, protective coatings, hydrogen storage, and energy storage.
[0004] 2D materials (such as graphene or TMDC) are typically grown on a growth substrate, processed, and then transferred to a target substrate.
[0005] However, to obtain high-quality materials, these 2D materials need to be grown at very high temperatures, potentially on a catalytic substrate. The growth temperatures required to obtain high-quality 2D materials are incompatible with semiconductor manufacturing, such as with integrated circuits or components previously formed on the target substrate to which the 2D material is to be applied.
[0006] Therefore, TMDC and graphene layers need to be grown on a specific substrate compatible with the required high temperature, and then transferred to the target substrate (with manufacturing capability) at a lower temperature.
[0007] One of the main reasons for the slow adoption of 2D materials (such as graphene and TMDC) in the semiconductor industry is the lack of compatibility between the tools, technologies and / or substrates commonly used in graphene research and those commonly used in the semiconductor industry.
[0008] For the past 15 years or so, most examples of graphene produced via CVD have involved growing a thin metal foil (copper / nickel, approximately 25 micrometers thick) and then removing it from the foil using a thin support (<1 micrometer) polymer film via wet chemical methods (metal etching, electrochemical delamination). This allows a floating graphene / polymer film to form on a liquid (typically deionized water). The graphene layer is then transferred to the target wafer / substrate by “scooping” it from the aqueous solution onto the target wafer. This technique is difficult to automate due to the complex transport mechanism of the 1-micrometer thin polymer film floating on the water layer. Furthermore, the wet scooping technique always leaves a thin water layer at the interface between the 2DM and the substrate / 2DM, which must be removed before further processing. However, some residual water molecules may remain, which has been shown to degrade device performance (doping, reduced mobility, transconductance hysteresis).
[0009] The transfer of transition metal dichalcogenides (TMDCs) grown on non-catalytic substrates via CVD, MOCVD, or ALD is very similar. Formulations in the literature typically involve etching the surface of the growth substrate and allowing the TMDC layer / polymer support to float on top of a liquid.
[0010] As the field moves towards wafer-level processing of 2D materials, several example carrier layers have emerged. Some of these carrier layers include stacks with heat-releasing bands or similar materials as carrier substrates. However, these carriers are incompatible with high-throughput or high-volume manufacturing, for example, due to incompatibility with various systems commonly used in semiconductor manufacturing or semiconductor manufacturing plants.
[0011] Known examples include systems comprising a support film (approximately 100 micrometers thick), a thermally released adhesive (approximately 50 micrometers thick), and a PMMA sacrificial layer (<1 micrometer thick). This provides some convenience for wafer-level transport and allows for packaged shipment to the foundry. However, carrier stacks still have two main drawbacks: 1) the flexible support layer is not easily manipulated by wafer transport robots, and 2) the thermally released adhesive is not considered suitable as a high-throughput carrier release method in a manufacturing environment.
[0012] Metal layers have been used in the literature to delaminate 2D TMDC layers with their growth substrates. In some examples, gold has been used. However, these methods and supports are incompatible with standard manufacturing techniques due to contamination risks. Recently, bismuth has been shown to be able to achieve dry delamination of TMDCs by combining it with a polymer support layer and a flexible heat-release tape (TRT) backing. However, this TRT backing layer is also incompatible with standard manufacturing techniques / high-volume manufacturing (HVM).
[0013] Therefore, there is a need for 2D material transfer systems and methods that are compatible with high-throughput or high-volume manufacturing (e.g., in semiconductor manufacturing plants). Summary of the Invention
[0014] The object of the present invention is to provide a carrier and method for reliably transferring a 2D material layer from its growth substrate to a fabrication-capable substrate.
[0015] In particular, the object of the present invention is to provide a method for producing a carrier stack for transferring 2D materials to a target substrate or wafer.
[0016] This is achieved by the method for producing carrier stacks as described in claim 1.
[0017] A further object of the present invention is to provide a method for transferring a 2D material layer from a carrier stack to a target substrate or wafer.
[0018] This is achieved by the method described in claim 11.
[0019] A further object of the present invention is to provide a carrier stack.
[0020] This is achieved through the carrier stack as described in claim 13.
[0021] Embodiments of the invention are claimed in the dependent claims.
[0022] The present invention aims to solve the aforementioned problems by designing a (semi)rigid carrier that allows 2D material to be transferred from a source wafer to a target wafer using automated wafer bonding, followed by the selective removal of the carrier layer using automated wafer debonding, thereby leaving a clean / complete 2DM on the target wafer.
[0023] In a first aspect, a carrier stack is provided for transferring a two-dimensional 2D material layer to a rigid target substrate. The carrier stack includes: - A rigid or semi-rigid carrier substrate (2), the rigid or semi-rigid carrier substrate having a first surface, and - A 2D material layer, which is bonded to the first surface of the carrier substrate by at least one adhesive layer (4, 6). The adhesive layer is configured to provide adhesion between the carrier substrate and the 2D material layer and allow the 2D material layer to subsequently detach from the carrier substrate.
[0024] In particular, the carrier stack can be produced by a method further described below and referred to as the second aspect.
[0025] A rigid or semi-rigid carrier substrate provides a temporary carrier configured to temporarily support a 2D material layer for transferring the 2D material layer from a growth substrate to a target substrate.
[0026] The carrier substrate can be advantageously reused.
[0027] At least one adhesive layer provides an adhesive layer and / or a sacrificial layer. At least one adhesive layer provides a temporary bond between the 2D material layer and the carrier substrate.
[0028] In the stack, the rigid or semi-rigid carrier substrate may have dimensions corresponding to the size specifications of the semiconductor wafer, wherein these dimensions include one or more of the following: substrate diameter, thickness, weight, opacity, and material.
[0029] Therefore, the carrier stack can be suitable for mass production, enabling it to be integrated into semiconductor manufacturing lines and / or used with conventional bonding / debonding tools.
[0030] The rigid or semi-rigid carrier substrate can be a wafer made of glass, sapphire, or silicon.
[0031] At least one adhesive layer may contain one or more adhesive materials that allow for thermal sliding or laser debonding.
[0032] At least one adhesion layer preferably comprises at least one of the following: polystyrene (PS), polylactic acid (PLA), polyvinyl alcohol (PVA), polybutyl acrylate (PBA), polyvinyl butyral (PVB), poly(methyl methacrylate) (PMMA), PPC, polycarbonate (PC), poly(benzyl methacrylate) (PBzMA), Brewerbond compound, or a metal, a eutectic containing a metal, or a metal compound. In embodiments, when the adhesion layer comprises a metal layer, the metal layer may comprise, for example, at least one of the following: bismuth, gold, indium, antimony, lead, tin, gallium; or a eutectic material comprising at least one of these, such as bismuth-tin; or a compound comprising at least one of these, such as indium-antimony. The use of metals, eutectics, or compounds with low melting points is considered advantageous, taking into account the promotion of thermal slip-off during subsequent transfer from the carrier stack to the target substrate.
[0033] In some embodiments, at least one adhesive layer may include an adhesive layer and a sacrificial layer.
[0034] 2D materials may include one or more of graphene, hexagonal boron nitride (h-BN), and transition metal dichalcogenide (TMDC) materials. Examples of TMDC materials include MoS2, MoSe2, WS2, and WSe2.
[0035] 2D materials can include stacks of 2D materials. For example, 2D materials can include multilayer stacks of one type of 2D material or heterostructure stacks (e.g., h-BN / graphene / h-BN stacks or MoS2 / WSe2).
[0036] This disclosure provides a carrier stack (also known as a transfer carrier) composed of multiple materials that form a universal 2D material transfer carrier for use with conventional wafer transfer systems and bonding / debonding tools.
[0037] 2DM can refer to a single or multiple layer of a two-dimensional material (e.g., graphene, h-BN, TMDC) in its growth state, or a heterostructure of such 2DM (e.g., h-BN / graphene / h-BN or MoS2 / WSe2). In this regard, the source wafer can refer to a growth wafer (e.g., a metal layer on a wafer-shaped substrate for graphene / h-BN, a sapphire or SiO2 wafer for TMDC), or it can refer to a temporary wafer on which a heterostructure is built before it is finally transferred to the target wafer.
[0038] In a second aspect, a method is provided for producing a carrier stack for transferring two-dimensional 2D material layers to a rigid target substrate. The method includes: - Provide a rigid or semi-rigid carrier substrate having a first surface; and - Coating at least one adhesion layer onto at least one of the first surface of the carrier substrate and the surface of the 2D material layer; and - Bond the 2D material layer to a rigid or semi-rigid carrier substrate using at least one adhesive layer; The steps involved in bonding the 2D material layer include: - Position the first surface of the carrier substrate to face the 2D material layer, which is supported by the growth substrate (12), and make the first surface contact the 2D material layer; - Bonding a 2D material layer to a carrier substrate by applying heat and / or pressure through at least one adhesive layer; and -The 2D material layer was then debonded from the growth substrate (debonding 1); Among them, the 2D materials (8) include one or more of graphene, hexagonal boron nitride (h-BN), and transition metal dichalcogenide (TMDC) materials; and in, When the 2D material includes graphene or h-BN, the debinding step includes an electrochemical process; and / or - When the 2D material includes a TMDC material, the adhesive layer contains a metal, a eutectic material containing a metal, or a metal compound, and the debonding step includes mechanical debonding.
[0039] The method described in the second aspect can be used to produce a carrier stack as described in the first aspect. Therefore, the method described in the second aspect can involve one or more of the features disclosed above with respect to the first aspect.
[0040] When the adhesive layer contains a metal, a eutectic material, or a metal compound, the adhesive layer may contain at least one of the following: bismuth, gold, indium, lead, tin, gallium; or a eutectic material containing at least one of these; or a compound containing at least one of these.
[0041] The electrochemical processes involved in the debonding step of 2D materials (such as graphene and h-BN) can be carried out in a device comprising: a container for holding an electrolyte solution; a substrate holding member disposed inside the container; a voltage source connectable to the surface of the 2D material layer and / or the growth substrate; an actuator for moving a carrier substrate away from the growth substrate, or vice versa; and a controller for controlling the actuator.
[0042] Debonding can be performed through the following steps: - Moving the edge of the carrier substrate away from the growth substrate (or vice versa) to provide separation space between the growth substrate and the 2D material layer, where the separation front is where the growth substrate and the 2D material layer begin to separate from each other; and - When the growth substrate (having a 2D material layer) and the carrier substrate are at least partially immersed in an electrolyte solution and a potential is applied to the 2D material layer and / or the surface of the growth substrate facing the 2D material layer, the separation space increases and the separation front moves along the growth substrate, wherein the electrolyte diffuses between the growth substrate and the 2D material layer, and wherein the actuator is controlled so that the advance of the separation front is equal to or less than the diffusion rate of the electrolyte.
[0043] Further details of the debonding process can be found in pending Dutch patent application 2033775, filed on December 21, 2022.
[0044] When the 2D material includes or is formed from TMDC material, the debonding of the 2D material from the growth substrate can be performed by mechanical debonding. For example, dry or wet debonding can be applied. It has been shown that this can be achieved with good results when the adhesive layer contains at least one of bismuth, gold, or a bismuth-containing eutectic material (such as bismuth-tin).
[0045] Furthermore, it has been observed that when the 2D material layer is further supported on the target substrate wafer and removed from the carrier substrate (i.e., debonding), the bonding of the TMDC 2D material with a layer containing at least one of bismuth, gold, or a bismuth-containing eutectic material (such as bismuth-tin) is well combined with the debonding technique applied in the second debonding step (such as thermal sliding debonding or similar thermally activated debonding).
[0046] The 2D material layer can be grown on a growth substrate, or can be configured to be grown on a growth substrate. According to this method, the 2D material layer is then transferred from the growth substrate to a carrier substrate. The growth substrate (also called the source substrate) can be a substrate suitable for growing 2D materials and capable of withstanding the temperatures and other process parameters applied during the growth of the 2D material layer.
[0047] As mentioned, the steps of debonding the 2D material layer from the growth substrate may include one or more of the following: mechanical debonding (e.g., peeling the 2D material from the growth substrate); chemical release (etching); electrochemical release of the 2D material from the growth substrate; or electrochemical delamination of the 2D material from the growth substrate.
[0048] When the debonding method involves an electrochemical process, electrical contact should be provided with the 2D material layer and / or the growth substrate on which the 2D material layer is initially supported.
[0049] Therefore, the method may further include making electrical contact with the surface of a growth substrate supporting the 2D material layer, the growth substrate including a metal surface, wherein the electrical contact is achieved by one of the following: (i) A metal strip is bonded at the outer edge of the growth substrate such that the metal strip is bonded between the growth substrate and the carrier substrate and allows electrical contact to realize the electrochemical process; (ii) A notch is formed in the carrier substrate to allow contact with the metal surface of the growth substrate via a contact element; or (iii) Before bringing the carrier substrate and the growth substrate into contact and performing the bonding step, the carrier substrate and the growth substrate are positioned misaligned and / or displaced relative to each other.
[0050] In alternative (i), the thin metal strip can be formed, for example, of copper (Cu). This thin metal strip can be bonded between the carrier substrate and the growth substrate to partially extend from the temporary stack. The strip can be electrically contacted to apply a voltage during the electrochemical debonding process.
[0051] In alternative (ii), the cutout in the carrier substrate can be used to contact the metal surface by using pins or clips as contact elements. The contact elements can be positioned through the cutout.
[0052] In alternative (iii), the substrates (e.g., wafers) can be positioned a few millimeters (e.g., about 5 mm) displaced relative to each other. This displacement exposes and makes the edges of the growth substrate accessible for positioning electrical contacts to apply voltage during the electrochemical process. Alternatively, a carrier substrate (e.g., a carrier wafer) with a smaller diameter than the growth substrate can be used, which also leaves sufficient area for providing electrical contacts. For example, a 4-inch carrier wafer can be used for 2D materials grown on a 6-inch wafer.
[0053] The materials used in at least one adhesive layer can be selected based on the debonding technology to be used.
[0054] The method may further include bonding a second 2D material layer on top of the 2D material layer to form a stack of 2D material layers on a carrier stack.
[0055] At least one adhesive layer may include an adhesive layer and a sacrificial layer, wherein the method may include applying the adhesive layer to a first surface of a carrier substrate and applying the sacrificial layer to a surface of the 2D material layer prior to bonding the 2D material layer to the carrier substrate.
[0056] In a third aspect, a method for transferring a two-dimensional 2D material layer to a rigid target substrate is provided, wherein the method described in the third aspect includes: - Produce carrier stacks by means of the method described in the second aspect; - Position the carrier stack so that the 2D material layer faces the target surface of the rigid target substrate; - Bonding a carrier stack to a target substrate, including bonding a 2D material layer to the target surface of the target substrate; and - Debond the carrier substrate from the 2D material layer.
[0057] This method results in the 2D material layers being supported by the surface of the target substrate and essentially directly bonded to that surface after the transfer of one or more 2D material layers to the target substrate.
[0058] The carrier stack as described in the first aspect and the methods described in the second and third aspects enable the transfer of wafer-scale 2D material layers from a source wafer to a target wafer. This enables high-volume manufacturing. The methods described herein can be performed using conventional semiconductor manufacturing tools and / or processes.
[0059] The carrier stack provides a universal carrier stack for temporarily carrying 2D material to be transferred from a source wafer to a target wafer. The carrier stack can be transported from the place where the 2D material layer is produced to different locations, where the 2D material layer is transferred to the target wafer (e.g., a target wafer or its components patterned with one or more parts or IC circuits).
[0060] The carrier stack can be specifically tailored or designed for the 2D material to be transferred and the technology or process to be used during the transfer process.
[0061] Further examples of the various features and aspects described above, their effects and advantages, can be understood from the following detailed description and accompanying figures. Attached Figure Description
[0062] Further features and advantages of the invention will become clear from the description of the invention by way of non-limiting and non-exclusive embodiments. These embodiments should not be construed as limiting the scope of protection. Those skilled in the art will recognize that other alternatives and equivalent embodiments of the invention can be conceived and practiced without departing from the scope of the invention. Embodiments of the invention will be described with reference to the various figures in these drawings, in which the same or identical reference numerals denote the same, identical, or corresponding parts, and in the drawings: Figure 1 illustrates a transfer carrier or carrier stack according to an embodiment of this disclosure. Figure 2 The illustration schematically depicts a method for transferring 2D material from a source substrate to a target substrate according to embodiments of this disclosure. Figure 3 It schematically shows, as Figure 2 An embodiment of the method for transferring graphene is shown; Figure 4 It schematically shows, as Figure 2 An embodiment of the method for transferring TMDC material is shown; Figure 5 The illustration schematically depicts a method for transferring 2D material from a source substrate to a target substrate according to embodiments of this disclosure. Figure 6 Examples of embodiments based on this disclosure are shown. Figure 5 The method details involve transferring 2D material from a source substrate to a carrier substrate to form a transfer carrier. Figure 7 Examples of embodiments based on this disclosure are shown. Figure 5 The details of the method involve transferring 2D material from a carrier substrate or transfer carrier to a target substrate. Detailed Implementation
[0063] Figure 1 illustrates a non-limiting embodiment of a carrier stack for transferring two-dimensional 2D material to a target substrate according to an embodiment of this disclosure.
[0064] The carrier stack is configured to achieve compatibility with conventional wafer transfer systems and bonding / debonding tools. The carrier stack can be transferred like a standard wafer, for example, in terms of characteristics or dimensional specifications (such as diameter, thickness, weight, opacity, material, etc.). The carrier stack can be transferred using conventional robotic wafer transfer devices, and the 2D material transfer process can be performed in conventional wafer bonding / debonding equipment. Therefore, the carrier stack can be integrated into semiconductor manufacturing lines.
[0065] The carrier stack comprises three main layers, each providing one or more functions for the transfer steps, as detailed below. Figure 2 These transfer steps are outlined.
[0066] The carrier stack 1 (also known as a transfer carrier) includes a rigid or semi-rigid carrier substrate 2 (also known as a carrier substrate or mechanical support layer). One or more adhesive layers are disposed on the surface of the substrate, including a first adhesive layer 4 or a temporary adhesive layer. A second adhesive layer or a sacrificial layer 6 may also be provided. The 2D material layer 8 is bonded to the carrier substrate 2 through the first adhesive layer 4 and the sacrificial layer 6.
[0067] In some embodiments, only one of the adhesive layer 4 and the sacrificial layer 6 may be provided. In those embodiments, which will be described in further detail below, the functions of the temporary adhesive layer 4 and the sacrificial layer 6 may be combined in a single layer. For example, a PMMA layer may be sufficient for the transfer of graphene layers, while a PBzMA layer may be sufficient for TMDC.
[0068] The 2D material layer can be one or more of the following: graphene, hexagonal boron nitride (h-BN), or transition metal dichalcogenide (TMDC) materials (e.g., MoS2, MoSe2, WS2, or WSe2).
[0069] The 2D material layer 8 can be a single layer of 2D material, as indicated in 8-1. Alternatively, the 2D material layer can be a multilayer 2D material 8-2 or a 2D material heterostructure 8-3, which comprises layers of different 2D materials stacked on top of each other, such as h-BN-graphene-h-BN.
[0070] As will be understood from the following description and examples, the carrier stack provides a wafer platform that can be fine-tuned for a specific 2DM transfer required.
[0071] The main functions of the carrier substrate 2 include: - Provides mechanical support for subsequent layers (i.e., one or more adhesive layers 4 and / or sacrificial layers 6 and 2D material layers 8). - Allows for automated transfer via wafer transfer robots, and - Compatibility with conventional wafer shipping containers and associated technologies.
[0072] The dimensions and / or characteristics of the carrier substrate (such as diameter, thickness, weight, opacity, and material) typically correspond to the dimensions and / or characteristics of industry-standard semiconductor wafers. This carrier substrate can be a silicon or glass wafer, or a plastic foil, with a thickness between 100 µm and 1000 µm and a diameter equal to that of the growth substrate and the target substrate, which typically comprise wafers and / or have wafer sizes. For example, a 200 mm diameter can be used, but other wafer diameters, such as 100 mm, 150 mm, or 300 mm, can also be used.
[0073] Examples of carrier substrate 2 include: i) Silicon wafers with a thickness in the range of 100 µm to 1000 µm (thinned or otherwise), for example, 300 µm silicon wafers can be used (may depend on the wafer diameter). ii) High-strength glass wafers with a thickness of 100 µm to 1000 µm (e.g., Schott Borofloat 33, Corning 7740, or CTE-matched glass wafers from the field of anodic bonding, such as LK5, Hoya SD-2, Asahi SW-YY). iii) Thermoplastic foil with suitable temperature / chemical / mechanical stability (thermal stability up to about 200°C, mechanical rigidity of about 1000 µm thickness, and chemical inertness at 200°C, insoluble in water, etc.).
[0074] The stiffness of the carrier substrate should provide mechanical stability to enable the transport and delivery of the stack without damaging or destroying the 2D material layer, and to enable the transfer of the 2D material layer from the growth substrate to the carrier substrate to form the carrier stack, and subsequently from the carrier stack to the target substrate.
[0075] The thickness of the mechanical carrier layer can be used to adjust the flexibility of the entire carrier stack. Flexible carriers allow for easier control of crack / front propagation in order to achieve controlled separation of the 2DM from the substrate using a moving linear leading edge. However, rigid wafers are preferred for automated wafer transport. Therefore, trade-offs need to be considered regarding carrier flexibility, depending on the specific 2DM / heterogeneous structure and carrier use case.
[0076] The carrier wafer can be configured (i.e. selected) according to the transfer technology used to transfer 2D materials.
[0077] The transfer process includes four main steps: - Bonding 1: Bonding the carrier substrate 2 to the 2D material layer 6 disposed on the growth substrate or source substrate; -Debonding 1: Debonding the 2D material layer from the growth substrate or source substrate (creating a carrier stack); - Bonding 2: Bonding the carrier stack, or more specifically, 2D material layers, to the target wafer; -Debonding 2: Debonding the 2D material layer from the carrier substrate, so that the 2D material layer has been transferred to the target substrate.
[0078] The following text is about Figure 2 And in specific embodiments regarding Figures 3 to 7 These steps are described in more detail.
[0079] For the debonding process compatible with the electrochemical transfer of graphene layers, the carrier wafer has one or more notches for placing the working / reference electrode clips. Furthermore, the carrier wafer can have a degree of flexibility to allow controlled propagation of the delamination front.
[0080] For debonding processes involving pulling (e.g., 1) electrochemical delamination of graphene or 2) dry / wet peeling of TMDC), the back side of the wafer may have areas / grooves / holes for grippers / hooks / suction cups. The front side of the wafer may be textured to increase the adhesion of the selected temporary adhesive.
[0081] The structure of the carrier substrate 2 can also be configured or selected based on various types of temporary debonding techniques, including thermal slip, thermal peeling, chemical release, or laser debonding. Compatibility with each of these release techniques can determine the selection or configuration of the carrier substrate. These requirements are well-established in the wafer bonding / debonding industry and can also be applied to the carrier stacks of this invention. For example: - For heat release methods, the carrier should have sufficient rigidity for use in conventional sliding debonding systems.
[0082] Chemical release typically requires solvent diffusion, which can be easily achieved by including small perforations in the carrier wafer to accelerate solvent diffusion.
[0083] Laser debonding requires transparency to the laser wavelength used for cutting / thermally decomposing temporary adhesives. In other words, glass wafers may be superior to silicon in this regard because they have higher transparency to wavelengths of 248 nm, 308 nm, 355 nm, and 532 nm.
[0084] Adhesive layer 4 (typically a temporary adhesive layer) provides the following functions: -Through the 2D material transfer steps outlined above, temporary adhesion between the carrier substrate 2 (e.g., wafer) and the 2D material 8 or sacrificial layer 6; - For example, compatibility with selective removal techniques at the debonding step 2, which includes chemical (dissolution / etching), thermal (thermal degradation, thermal softening), and / or optical (optical cleavage of polymer chains) debonding processes; and - Provide mechanical coupling between the carrier substrate 2 and the sacrificial layer 6 / 2D material layer 8.
[0085] Adhesive layer 4 is selected to be compatible with all four steps of the transfer process and can be selected more specifically based on the debonding technology to be used.
[0086] For example, when using a sliding debonding technique, one can choose polystyrene (PS), polycarbonate (PC), polylactic acid (PLA), polyvinyl alcohol (PVA), polybutyl acrylate (PBA), polyvinyl butyral (PVB), poly(benzyl methacrylate) PBzMA, poly(methyl methacrylate) PMMA, or commercial Brewerbond compounds.
[0087] Alternatively, adhesive layer 4 may include an adhesive specifically designed for the intended process.
[0088] Sacrificial layer 6 is typically selected based on the 2D material to be transferred.
[0089] The functions of a sacrificial layer typically include one or more of the following: - Provides controlled interaction or adhesion with 2D materials; -Through the transfer step to provide mechanical and / or chemical protection to 2D materials; and - To prevent 2D materials from being contaminated by adhesive layer 4 (temporary adhesive); and - Allows for the selective and non-destructive removal of the sacrificial layer from the 2D material after transfer.
[0090] The sacrificial layer 6 can also be further selected based on the method (debonding 1) used to remove the 2D material layer from the growth substrate or the source substrate.
[0091] In the case of electrochemical transfer of graphene from a metal catalyst wafer, the sacrificial layer is preferably insoluble in water, non-conductive, tough / robust, flexible, and allows for conformal contact between the graphene and the target wafer. Therefore, thermoplastic polymers such as PMMA, PC, and PPC are good choices.
[0092] In cases where graphene is peeled off from the growing metal, it has been shown that metal stress source layers (such as gold, nickel, cobalt, etc.) are suitable.
[0093] Similarly, in the case of dry / semi-dry peeling of the transition metal dichalcogenide (TMDC) layer from the growth wafer, inorganic layers (e.g., gold or bismuth, or eutectic materials such as bismuth-tin) as mentioned above can be used to provide strong adhesion to sulfur, or act as a stress-generating layer to reduce adhesion. Alternatively and / or additionally, organic materials (e.g., polymers, such as those mentioned above) are expected to act as stress-generating layers due to thermal stress following heat treatment (e.g., baking), and can be expected to facilitate easier delamination / debonding.
[0094] Therefore, this disclosure provides a carrier stack that can be specific to the 2D material to be transferred by selecting a suitable sacrificial layer. This carrier stack can provide a platform for transferring many different 2D materials and their stacks. The carrier substrate and temporary binder can be mass-produced, typically at a low cost. The sacrificial layer can be deposited onto a 2DM / source wafer, and then the prepared growth wafer can be attached to the wafer carrier stack using an adhesive step as needed.
[0095] According to this disclosure, a carrier stack comprising a 2D material layer or a 2D material heterostructure bonded to a carrier wafer can be provided to a wafer foundry / manufacturing plant, and using the stack, the 2D material / heterogeneous structure can be integrated into the device wafer using conventional bonding / debonding tools available in the wafer foundry / manufacturing plant. The carrier stack according to this disclosure thus enables the integration of 2DM transfer using conventional tools compatible with HVM.
[0096] Figure 2 The present disclosure schematically illustrates a method for transferring 2D material from a source substrate to a target substrate using a transfer carrier or carrier stack as shown in FIG1, according to an embodiment of the present disclosure.
[0097] In step 210 (also known as bonding 1), the carrier substrate 2 is positioned facing the 2D material layer 8 supported by the source wafer 12. The carrier substrate 2 is a rigid or semi-rigid substrate or wafer, as described with reference to FIG1.
[0098] The source wafer 12 (also known as the growth substrate) can be a wafer on which a 2D material layer has already been grown. Typically, the growth substrate is a substantially rigid substrate, usually a wafer or having wafer-sized specifications.
[0099] Prior to the bonding process, the carrier substrate 2 may be coated with an adhesive layer 4 and / or a 2D material layer may be coated with a sacrificial layer 6, as described with respect to Figure 1. This can be done, for example, by evaporation, spin coating, or spraying of the layers onto any of these substrates prior to bonding.
[0100] The carrier substrate 2 is brought into contact with the 2D material / source wafer stack, such that the 2D material layer is bonded to the carrier substrate 2 via adhesive layer 4 and / or sacrificial layer 6 (if present), or directly bonded to the surface of the carrier substrate in the absence of adhesive layers 4 and 6. Bonding can be performed by applying heat and / or force / pressure to the carrier wafer and the source wafer when they are in contact with each other.
[0101] In step 220 (also known as debonding 1), the 2D material layer 8 is removed from the source wafer 12. After debonding, the 2D material layer is supported by the carrier wafer 2. The carrier stack 1 has been formed.
[0102] Debonding (debonding 1) can be carried out by various known techniques, such as wet / dry peeling of 2D materials from the growth substrate or electrochemical release of graphene from the growth catalyst metal.
[0103] In step 230 (also known as bonding 2), the 2D material layer is bonded to the target substrate 14. Hereinafter, the carrier stack 1 is positioned such that the 2D material layer 8 faces the surface of the target substrate 14 and is bonded to that surface during bonding 2.
[0104] In step 240 (debonding 2), the carrier substrate 2 is debonded from the 2D material layer 8 positioned on the target substrate 14. The carrier substrate 2 is removed from the 2D material layer / target substrate stack, leaving the 2D material layer intact and substantially uncontaminated on the target substrate.
[0105] Alternatively, after bonding 2 in step 230, in step 235, which includes the second bonding 2 process, the carrier stack can be positioned above the second 2D material (source substrate stack), and the second 2D material layer can be transferred onto the 2D material layer already located on the carrier stack to form a 2D material multilayer 8-2 or heterogeneous layer 8-3 stack.
[0106] As described above and as... Figure 2 The illustrated four-step transfer process shows that the carrier substrate 1 forms a temporary carrier, thereby carrying the 2D material layer from the source wafer or growth wafer 12 to the target wafer or fabrication wafer 14. In some embodiments, the carrier substrate 2 can be reused after debonding and appropriate cleaning.
[0107] As has been seen, the carrier stack 1 produced and used in the transfer method described above allows for defect-free transfer of 2D material from the source wafer to the target wafer. The bonding step 230 and the debonding step 240 (bonding 2, debonding 2) are compatible with conventional semiconductor bonding / debonding tools and allow for high-volume manufacturing, typically at a lower cost.
[0108] Figure 3 The above references are illustrated schematically. Figure 2 Implementation of the method for transferring graphene as described.
[0109] In method 300, a thermally sliding support for graphene transfer is prepared in step 302. The support substrate 2 (formed herein from a glass wafer with a thickness of 300 µm) is coated with an adhesive layer 4. In the illustrated embodiment, this is performed by spin-coating a low molecular weight PMMA material onto the glass wafer. Well-defined edge beads can be used to allow controlled electrolyte diffusion in a subsequent debinding step.
[0110] In step 304, graphene layer 8 has been grown on the metal catalyst wafer forming source wafer 12. Graphene layer 8 is covered by sacrificial layer 6, which is formed by spin-coating high molecular weight PMMA material onto the graphene.
[0111] The order in which steps 302 and 304 are performed is not required.
[0112] Subsequently, in step 310, during bonding 1, a thermal sliding carrier formed by a glass wafer 2 coated with an adhesive layer 4 is bonded to a graphene 8 located on a source wafer 12 and covered with a sacrificial layer 6.
[0113] In step 320 (debonding process 1), the graphene layer 8 is removed from the source wafer 12 using, for example, electrochemical delamination. This forms the carrier stack 1.
[0114] Therefore, the resulting carrier stack 1 can be stored and / or transported to a semiconductor manufacturing plant or foundry for subsequent steps 330, 340 of transferring the graphene layer to the target wafer.
[0115] In step 330, during bonding 2, the graphene layer 8 is bonded to the target wafer 14 (e.g., a 90 nm thick silicon or silicon oxide wafer). This can be performed in a standard bonding tool.
[0116] In step 340, during debonding 2, the carrier substrate 2 is debonded from the graphene layer. In the illustrated embodiment, this is performed by thermal sliding debonding using a standard debonding tool. Herein, the low molecular weight (low MW) PMMA forming the adhesive layer 4 will soften due to heating, and the viscosity of the softened low molecular weight PMMA will allow the glass wafer to slide off the target wafer 14 and the graphene coated with high molecular weight PMMA.
[0117] High molecular weight PMMA can be removed from the graphene layer and the target wafer using various known techniques, leaving a complete, uncontaminated graphene layer 8 supported by and in direct contact with the surface of the target wafer 14.
[0118] Figure 4 schematically shown Figure 2 The embodiment of the method for transferring TMDC material is shown. The general steps of method 400 substantially correspond to the steps of method 300, and therefore unnecessary repetition will be avoided.
[0119] In step 402, a thermal sliding carrier for TMDC transfer is prepared. A low molecular weight PBzMA material is spin-coated onto a silicon wafer 2 to form an adhesive layer 4 on the silicon wafer.
[0120] In step 404, a source wafer stack is prepared. A TMDC layer 8 has already been formed on source wafer 12, which is represented herein by a sapphire substrate. A sacrificial layer 6 is formed by evaporating bismuth onto the TMDC layer 8 and source wafer 12.
[0121] In step 410, the prepared thermally sliding carrier and the source wafer are bonded together during bonding 1. The carrier substrate 2 is positioned such that the low molecular weight PBzMA faces the bismuth layer on the TMDC / sapphire wafer, and the two wafers are placed together such that the TMDC layer 8 is bonded to the carrier wafer 2 through the bismuth layer and the PBzMA layer.
[0122] In step 420, the TMDC is removed from the source wafer during debonding 1. This can be performed by mechanical debonding. A carrier stack 1 is then formed.
[0123] In step 430, the TMDC layer is bonded to the target wafer 14 during bonding 2. This can be performed using standard bonding tools.
[0124] In step 440, during debonding 2, the carrier substrate 2 is debonded from the TMDC layer. This can be performed by thermal sliding debonding using a standard sliding debonding tool. The viscosity of low molecular weight PBzMA decreases significantly at temperatures above 180°C, thus allowing mechanical sliding.
[0125] Following debonding, a cleaning process is applied to the TMDC surface to remove any remaining PBzMA and / or metal. For example, PBzMA residue can be removed by O2 reactive ion etching or barrel etching. In this step, the metal layer provides protection for the 2D material layer to prevent damage from etching. Subsequently, the metal layer can be removed by dissolving it in an inorganic solvent.
[0126] Therefore, similar to method 300, the complete, uncontaminated TMDC layer 8 is supported by and in direct contact with the surface of the target wafer 14.
[0127] Figure 5The illustration schematically depicts a general transfer process for transferring a 2D material layer 8 from a source substrate 12 to a target substrate according to embodiments of this disclosure. Figure 5 In this embodiment, the TMDC layer is transferred from the source substrate to the silicon / silicon oxide wafer forming the target wafer 14. In this embodiment, the sacrificial bismuth layer 6 serves as an adhesion layer. Alternatively, a carrier wafer may also support the adhesive layer 4 as described in the embodiments above.
[0128] In step 504, TMDC is grown on growth substrate 12. In step 540, the TMDC has been transferred to target substrate 14. This is achieved through bonding process 1 510, debonding process 1 520, bonding process 2 530, and debonding process 2 540, which correspond to the above-mentioned processes regarding... Figure 2 , Figure 3 and Figure 4 The process described.
[0129] In such Figure 5 In the method shown, the thin layer made of bismuth or other low-melting-temperature metals or alloys enables the TMDC layer to be transferred from its growth substrate 12 to the target substrate 14 using standard bonding and debonding tools.
[0130] exist Figure 5 In this method, using only bismuth as the functional layer (also referred to herein as the adhesive layer) allows steps 510 to 540 to be successfully performed. As mentioned above in the description of Figure 1 and the carrier stack, in some embodiments, the functions of the adhesive layer 4 and the sacrificial layer 6 can be performed by a single layer. Figure 5 In some embodiments, this is achieved by depositing or coating a bismuth layer onto the TMDC layer. Additional adhesive layers and / or sacrificial layers may be used, but these are not necessary to achieve the transfer.
[0131] As described above, the carrier substrate 2 is a rigid or semi-rigid temporary carrier, which facilitates the use of HVM-compatible tools and techniques to perform the transfer process.
[0132] In step 504, bismuth (or another metal) is evaporated (or deposited by other techniques) onto the TMDC / growth substrate.
[0133] In step 510, a temporary carrier 2 (e.g., a silicon or silicon oxide wafer) is bonded to the bismuth surface during bonding 1. The surface of the carrier wafer may be textured or roughened to increase the surface area contact between the carrier wafer and the bismuth layer.
[0134] In step 520, the temporary carrier 2 (now bonded with the TMDC layer) is debonded from the growth substrate 12. In this step, the TMDC should be separated from the growth substrate, not from the metal layer. This can be achieved by the debonding method 1 described above. Thus, the carrier stack 1 is formed.
[0135] In step 530, the carrier stack 1 is bonded to the target wafer 14 during bonding 2.
[0136] In step 540, during debonding 2, the temporary carrier 2 is debonded from the target wafer and the TMDC layer 8 now bonded to the target wafer. This is facilitated herein by the low melting temperature of bismuth, or alternatively its alloys, or another low-melting-temperature metal as described above. The low melting temperature allows for sliding separation at temperatures compatible with subsequent processes in IC manufacturing. In this step, the TMDC layer remains intact on the target wafer 14 without being damaged by the sliding of the bismuth layer.
[0137] Subsequently, after the carrier wafer has detached and slid off from the TMDC / target wafer, any remaining bismuth on the TMDC surface is removed from that surface. This can be achieved by dissolving the bismuth layer with an acidic solvent.
[0138] Figure 5 The process provides a simple procedure involving only a single metal layer and a (semi-)rigid temporary support. When the (semi-)rigid support is wafer-sized, standard HVM tools can be used for this process.
[0139] In the embodiments described herein, bismuth has been used because good adhesion to the TMDC layer has been observed. Furthermore, the use of a bismuth layer has been shown to increase the probability that the TMDC layer will delaminate from the surface of the growth substrate without the need for interstitial materials (H2O, KOH, H2O solution, etc.).
[0140] A further advantage of bismuth is its low melting temperature. This allows the transfer process to proceed at low temperatures. Furthermore, the low melting temperature is believed to create a good conformal contact after step 530. In contrast, gold or other metals with high melting temperatures would not allow this.
[0141] Finally, bismuth is a metal and can dissolve in acidic aqueous solutions that do not leave residues on the surface and do not chemically erode the TMDC layer.
[0142] As a substitute for bismuth, eutectic bismuth alloys, such as BiSn alloys, can be used. These materials are used for welding (they are readily available) and melt at even lower temperatures.
[0143] The melting temperature of bismuth or other low-melting-temperature metals, eutectics or alloys, and phase transitions between solid and liquid phases are used during the transfer process: solid phase is used in debonding 1, phase transitions between solid and liquid phase are used in bonding 1 and bonding 2, and liquid phase (thermal sliding) is used in debonding 2.
[0144] In addition to providing good mechanical adhesion and promoting the integrity of the TMDC layer throughout the transfer process, bismuth or alternative sacrificial layers, as described herein, can also provide protection for the TMDC layer. In embodiments where an adhesive layer 4 (typically one or more polymer layers) is required above the bismuth layer (e.g., to achieve flexibility or adhesion to a flexible carrier), the bismuth layer separates the 2D material from the polymer layer while protecting the 2D material from polymer residues (metal layers are easier to remove than polymer / adhesive layers).
[0145] Figure 6 Showing Figure 5 Details of the bonding process 1 and the debonding process 1 of the method.
[0146] In these steps, TMDC is detached from its growth substrate and transferred to a temporary support using a bismuth layer. These steps take advantage of the good adhesion between the bismuth layer and the TMDC.
[0147] In step 504a, the growth wafer 12 with the TMDC layer 8 and the carrier substrate 2 (e.g., a (semi)rigid wafer) are positioned facing each other but at a certain distance from each other.
[0148] In step 504b, a bismuth layer has been applied to one of these wafers. Figure 6 In the illustrated embodiment, the bismuth layer has been applied to the TMDC layer on the growth substrate. This bismuth layer can be evaporated from bismuth pellets / powder (PVD deposition) or potentially melted onto the top of the TMDC layer. In an alternative embodiment, the bismuth layer can be applied to the surface of the carrier substrate 2.
[0149] In step 510a, the carrier substrate 2 is bonded to the growth wafer 12 carrying the TMDC covered with a bismuth layer. This can be performed in a standard wafer bonder tool. The temperature and the force / pressure applied to the wafer are selected to achieve proper bonding. In one embodiment, bonding 1 can be achieved by melting the bismuth layer and pressing the (semi-)rigid wafer on top. In another embodiment, bonding 1 can be performed at room temperature while applying higher pressure to the bismuth layer and the wafer.
[0150] At step 510b, at the end of bonding 1, the growth substrate and the carrier wafer are bonded together by the bismuth layer.
[0151] Steps 520a to 520c illustrate the debonding process 1. According to the general concept of this process, the separation of the TMDC from its growth substrate is initiated via the bismuth layer. It has been observed that H2O or other intercalators are not required for this. The (semi-)rigid support substrate is configured to mechanically support the bismuth layer without fracturing and allows for a controlled separation front velocity. The ultimate goal of debonding 1 is the removal of the TMDC layer from the growth substrate, supported by the temporary support wafer via the bismuth layer.
[0152] In step 520a, at the start of the debonding process (as at the end of bonding 1 process), the growth substrate and the temporary support are bonded together by the bismuth layer.
[0153] In step 520b (debonding process 1), the carrier wafer 2 is pulled away from the growth substrate in a controlled manner. In some embodiments, a wedge may be used to initiate (and help control) the wafer separation. Alternatively, a roller may be applied to the top of the carrier wafer to allow controlled leading edge propagation. Details herein are described in pending Dutch patent application 2033775, filed December 21, 2022.
[0154] In some embodiments, a polymer layer may be added between the bismuth layer and the carrier wafer 2. For example, a polymer layer that allows for laser debonding may be used.
[0155] Figure 7 Showing with Figure 5 Details of the bonding 2 process and the debonding 2 process of the method, which are in Figure 6 It is executed after the method steps.
[0156] In step 530a, at the start of the bonding 2 process, a carrier substrate (TMDC layer stack) generated by the bonding 1 / debonding 1 sequence is prepared (e.g., as shown in the image). Figure 6 (as shown) and the target wafer.
[0157] In step 530b (bonding process 2), the carrier / TMDC / target wafer is placed together and bonded in a conventional bonding tool. The bismuth layer can be softened by raising the temperature to a temperature T close to or above the bismuth melting temperature, allowing the TMDC layer to conformally contact the target substrate.
[0158] In step 530c, at the end of bonding 2, the carrier / bismuth / TMDC / target wafer is thus bonded together.
[0159] In step 540a, the debonding process 2 begins.
[0160] In step 540b (debonding process 2), the bismuth layer (or other low melting temperature metal, eutectic or alloy) melts and the wafers slip off each other.
[0161] In step 540c, at the end of the sliding debonding process 2, the TMDC is located on the target substrate 14. Some bismuth layer may still remain on top of the TMDC layer. The remainder of the bismuth layer lies on the carrier substrate 2, which can be cleaned / reprocessed.
[0162] Finally, in step 540d, which indicates the end of the debonding process 2, any bismuth residue in the TMDC layer can be removed using, for example, an HNO3:H2O solution. The intact and uncontaminated TMDC layer is then supported and advantageously in direct contact with the surface of the target substrate.
[0163] As mentioned above, bismuth layers allow all the above steps to be performed using a single support and the HVM tool. In this paper, the low melting point of bismuth and the transition from the solid to the liquid phase are utilized.
[0164] The table below summarizes the state of the bismuth layer at different processing steps.
[0165]
[0166] Those skilled in the art will understand that the scope of the present invention is not limited to the examples discussed above, but can be modified and altered in various ways without departing from the scope of the invention as defined in the appended claims. While the invention has been shown and described in detail in the drawings and specification, such showing and description are intended to be illustrative or exemplary, and not restrictive. The invention is not limited to the disclosed embodiments, but includes any combination of the disclosed embodiments that can provide advantages.
[0167] By studying the accompanying drawings, description, and appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments in practicing the claimed invention. In the description and claims, the word "comprising" does not exclude other elements, and the indefinite article "a" or "an" does not exclude a plurality. In fact, it should be interpreted as "at least one." The mere fact that certain features are listed in different dependent claims does not indicate that combinations of these features cannot be advantageously used. All reference numerals in the claims should not be construed as limiting the scope of the invention. Features of the above embodiments and aspects can be combined unless their combination results in an obvious technical conflict.
Claims
1. A method for producing a carrier stack (1) for transferring a two-dimensional 2D material layer (8) to a rigid target substrate (14), the method comprising: - Provide a rigid or semi-rigid carrier substrate having a first surface (2); as well as - At least one adhesion layer (4, 6) is coated on at least one of the first surface of the carrier substrate and the surface of the 2D material layer; and -The 2D material layer (8) is bonded to the rigid or semi-rigid carrier substrate by at least one adhesive layer. The step of bonding the 2D material layer includes: - Position the first surface of the carrier substrate facing the 2D material layer, which is supported by the growth substrate (12), and make the first surface contact the 2D material layer; - Bonding the 2D material layer to the carrier substrate by applying heat and / or pressure through the at least one adhesive layer; and -Then the 2D material layer is debonded from the growth substrate; The 2D material (8) includes one or more of graphene, hexagonal boron nitride (h-BN), and transition metal dichalcogenide (TMDC) materials; and in, When the 2D material includes graphene or h-BN, the debinding step includes an electrochemical process; and When the 2D material includes TMDC material, the adhesive layer contains metal, eutectic material or metal compound, and the debonding step includes mechanical debonding.
2. The method according to claim 1, wherein, The adhesive layer comprises at least one of the following: bismuth, gold, indium, lead, tin, gallium; or a eutectic material comprising at least one of these; or a compound comprising at least one of these.
3. The method according to claim 1 or 2, wherein, The step of debonding the 2D material layer from the growth substrate includes one or more of the following: mechanically debonding the 2D material from the growth substrate; electrochemically releasing the 2D material from the growth substrate; or electrochemically delaminating the 2D material from the growth substrate.
4. The method according to any one of the preceding claims, wherein, The 2D material layer contains graphene or h-BN, and the step of debonding the 2D material layer from the growth substrate includes a combination of electrochemical processes and mechanical debonding.
5. The method according to claim 4, further comprising: Electrical contact is made with the surface of the growth substrate supporting the 2D material layer, the growth substrate including a metal surface, wherein the electrical contact is achieved by one of the following: - A metal strip is bonded at the outer edge of the growth substrate, such that the metal strip is bonded between the growth substrate and the carrier substrate and allows electrical contact to achieve the electrochemical process; - Cutouts are made in the carrier substrate to allow contact with the metal surface of the growth substrate via contact elements; or - Before bringing the carrier substrate and the growth substrate into contact and performing the bonding step, the carrier substrate and the growth substrate are positioned misaligned and / or displaced relative to each other.
6. The method according to any one of the preceding claims, further comprising: A second 2D material layer is bonded on top of the 2D material layer to form a stack of 2D material layers on the carrier stack.
7. The method according to any one of the preceding claims, wherein, The at least one adhesive layer includes an adhesive layer and a sacrificial layer, and the method includes applying the adhesive layer to a first surface of the carrier substrate and applying the sacrificial layer to a surface of the 2D material layer before bonding the 2D material layer to the carrier substrate.
8. The method according to any one of the preceding claims, wherein, The rigid or semi-rigid carrier substrate has dimensions corresponding to the size specifications of the semiconductor wafer, wherein these dimensions include one or more of the following: substrate diameter, thickness, weight, opacity, and material.
9. The method according to any one of the preceding claims, wherein, The rigid or semi-rigid carrier substrate is a wafer made of glass, sapphire, or silicon.
10. The method according to any one of the preceding claims, wherein, The at least one adhesion layer (4, 6) comprises at least one of the following: PMMA, PPC, PC, PBzMA, bismuth, gold, or a eutectic material, such as bismuth-tin.
11. A method for transferring a two-dimensional 2D material layer (8) to a rigid target substrate (14), the method comprising: - The carrier stack (1) is produced by the method according to any one of claims 8 to 17. - Position the carrier stack such that the 2D material layer faces the target surface of the rigid target substrate; - The carrier stack is bonded to the target substrate by bonding the 2D material layer to the target surface of the target substrate; as well as - Debond the carrier substrate from the 2D material layer.
12. The method according to claim 11, wherein, The step of debonding the carrier substrate from the 2D material layer includes thermal sliding debonding.
13. A carrier stack (1) for transferring a two-dimensional 2D material layer (8) to a rigid target substrate (14). in, The carrier stack has been produced by the method according to any one of claims 1 to 10, and the carrier stack comprises: - Rigid or semi-rigid carrier substrate (2), and - The 2D material layer (8) is bonded to the carrier substrate (2) by at least one adhesive layer (4, 6). The adhesive layer comprises at least one of the following: PMMA, PPC, PC, PBzMA, metal, eutectic material containing metal, or metal compound; and the adhesive layer is configured to provide adhesion between the carrier substrate and the 2D material layer and allow the 2D material layer to subsequently detach from the carrier substrate.
14. The carrier stack according to claim 13, wherein, The 2D material includes one or more of graphene, hexagonal boron nitride (h-BN), and transition metal dichalcogenide (TMDC) materials.
15. The carrier stack according to claim 13 or 14, wherein, The adhesive layer contains at least one of the following: bismuth, gold, indium, lead, tin, gallium; or a eutectic material containing at least one of these; or a compound containing at least one of these.
16. The carrier stack according to claim 13 or 14, wherein, The rigid or semi-rigid carrier substrate has dimensions corresponding to the size specifications of the semiconductor wafer, wherein these dimensions include one or more of the following: substrate diameter, thickness, weight, opacity, and material.
17. The carrier stack according to any one of claims 13 to 16, wherein, The rigid or semi-rigid carrier substrate is a wafer made of glass, sapphire, or silicon.
18. The carrier stack according to any one of claims 13 to 17, wherein, The at least one adhesive layer contains one or more adhesive materials that allow for thermal sliding or laser debonding.
19. The carrier stack according to any one of claims 13 to 18, wherein, The 2D material comprises a stack of 2D materials.