A welding method for producing an extended master.

Abstract

The present invention relates to a method for producing an enhanced master for an imprinting process, in which at least two masters are fused together, at least one master at least partially comprising at least one textured region. A photosensitive resin is applied at least between the at least two masters, and light from a light source is guided into a waveguide system to harden the photosensitive resin at least between the at least two sub-masters when it contacts the waveguide system. Further objects of the invention are the enhanced master obtained by this method, the imprinted product obtained from this enhanced master, and an apparatus for producing an enhanced master by implementing this method.

Description

[Technical Field]

[0001] The present invention relates to a method for fabricating nano-textured and / or micro-textured expanded master molds.

[0002] Nano- and micro-textured surfaces can be found in an increasing number of applications. In these applications, the textured surface can increase the functionality of the device (e.g., the efficiency of a photovoltaic module) or enable entirely new functionality (e.g., holographic displays). These textured surfaces are often applied to products by replicating the texture from a master using methods such as injection molding or nanoimprint lithography.

[0003] Fabricating a master is often costly and time-consuming. Furthermore, mastering techniques have limitations on the maximum surface area to which a texture can be applied. Some applications require a textured surface area that exceeds the limits of the mastering technology. For these applications, a smaller master may be scaled up, i.e., enlarged, to meet the dimensional requirements. For other applications, it is possible to create a master with the required textured surface area, but for economic reasons, a scaled-up master is preferred. For example, a scaled-up master can be used to replicate multiple smaller products per replication cycle. Most methods for scaling up textured masters can be divided into two categories.

[0004] The first category consists of step-and-repeat methods, in which (usually identical) textured patterns are printed multiple times on a larger substrate. The printed subcells are typically separated by non-textured bands, as described, for example, in U.S. Patent Application Publication No. 20130153534, or overlap each other, as described, for example, in M.K. Kwak et al., Material Horizons Vol. 2, 2015, pp. 86-90 (doi: 10.1039 / c4mh00159a). In both cases where UV nanoimprint lithography is used as the imprinting technique, significant challenges exist in preventing the UV-curable resin from spilling into undesired locations and causing cross-contamination between subcells. This challenge imposes limitations on the textures, imprint pressures, and resin types that can be used.

[0005] The second category of methods for fabricating an extended master consists of physically joining multiple smaller masters together to form an extended master, as described, for example, in CN105911815 and unpublished European Patent Application No. 19202151.7 in the applicant's name. This approach typically does not pose a risk of cross-contamination between subcells. However, different masters are connected by seams that can disrupt the appearance of the scaled-up texture, interfere with subsequent imprinting processes, and / or deteriorate over time. Therefore, it is often desirable to obtain smooth, thin, and durable seams. CN105911815 describes a method for achieving high-quality seams by filling the seams from behind with a curable resin while using a peelable adhesive tape to seal and glue the seams together. CN107121890 describes a method for fabricating large-area nanomolds using a photocurable resin on a transparent substrate and a light-shielding strip (e.g., metal or black resin) in the seam area. The uncured resin and the light-shielding strip can be removed after imprinting.

[0006] Korean Patent Publication No. 2012-0082266 discloses a lateral bonding process for fabricating large-area nanotemplates. For this process, a curable resin is used between different units. U.S. Patent Application Publication No. 2016 / 0033818 teaches the fabrication of large-scale patterns in which multiple pattern structure units are on the same plane and connected via resin between the units.

[0007] U.S. Patent Application Publication No. 2018 / 0113242 discloses a method for manufacturing a pattern structure. The primary focus of the document is the process of cutting a wafer into different surfaces. However, the document also discloses that different unit pattern structures are aligned with each other. To combine the different unit pattern structures, a liquid resin is provided between a first unit pattern structure and a second unit pattern structure. The resin is a thermosetting resin or a photocurable resin.

[0008] The present invention describes an alternative method for controllably physically welding multiple masters together, which results in a welded seam with high optical and mechanical quality.

[0009] Consequently, the present invention relates to a method for producing an extended master for an imprint process, wherein at least two masters are fused together, at least one master comprising at least one textured region, a photosensitive resin is applied at least between the at least two masters, and light from a light source is guided into a waveguide system to harden the photosensitive resin at least between the at least two sub-masters when the photosensitive resin contacts the waveguide system.

[0010] The method involves placing multiple textured (sub)masters in close proximity to one another and in close proximity to or direct contact with an optical waveguide system. Ultraviolet and / or visible light is coupled into the waveguides at one or more edges of the waveguide system or via one or more internal coupling structures. A light-sensitive, photocurable resin in the waveguide system is applied from the back boundary of the (sub)master to the seam, where the photocurable resin flows into the seam area under the influence of capillary and / or gravity. When the resin locally contacts the waveguides of the waveguide system, light from the waveguides can escape, controllably curing the resin before it spreads (undesirably) along the (textured) boundary of the master. To make this work, the difference between the refractive index of the uncured resin and the refractive index of the waveguide material is preferably less than 0.2, more preferably less than 0.1, and most preferably less than 0.05, to disrupt total internal reflection of light within the waveguide material. Once the resin has cured, a welded seam is created between the two masters. Optionally, a backing plate or sheet can be attached to the back of the extended master once the welding process is complete, after which the waveguide can be removed from the extended master.

[0011] The resulting expanded master consists of multiple smaller units (masters) that are fused together to form a larger master array. The joints or fusion seams between the smaller masters are made from a light-curable resin that contacts the light of the optical waveguide system, resulting in smooth and durable seams. The resulting imprinted products are therefore also of higher quality and have less variation in seam height and width compared to prior art products.

[0012] The present invention further relates to imprinted products obtained from the enhanced masters.

[0013] According to claim 1, at least two masters are fused together. However, the extended master may comprise three, four, five, or more than six masters fused together to form the extended master. At least one of the masters comprises at least a partially textured area. The textured area has a relief pattern that is the inverse of the imprint texture provided on the substrate. In one embodiment, all or more than one, preferably two, more preferably three, and most preferably more than half of the masters comprise at least a partially textured area. The textured area may extend over the entire master area or over only a portion of the master. If the textured area extends over only a portion of the master, preferably at least 60%, more preferably at least 80%, and most preferably at least 90% of the master area comprises a textured area. It is also possible to use masters with different textured areas (i.e. different relief patterns) and / or masters with differently sized textured areas (i.e. masters with different sizes of textured areas).

[0014] In one embodiment, at least one master is positioned such that at least one textured region of the master is oriented toward the waveguide system and / or at least one of the masters is at least partially in contact with the waveguide system. The term "partial contact" preferably means direct contact. In a preferred embodiment, at least one master includes a textured region, and the textured region of the at least one master is in direct contact with the waveguide system. The term "direct contact" means that the textured region and / or the master are in physical contact with the waveguide system, with no additional material (layer, air) between the waveguide system and the textured region. This configuration allows the light of the waveguide system to directly leak out when the resin contacts the waveguide system, quickly curing the resin without delay. This prevents undesired spreading of the resin over a portion of the master (e.g., over the textured region). Due to the preferred configuration of the master facing the waveguide system with its textured region, the resulting weld seam is at a level substantially equal to the height of the textured region. Therefore, the force distribution applied to the substrate during the imprint process is equal across the entire portion of the substrate and is not affected by seams, thereby improving the quality of the resulting imprinted product.

[0015] In one embodiment, at least one master is positioned so that at least one textured region of the master is oriented away from the waveguide system and / or at least one rear surface of the master is at least partially in contact with the waveguide system. The term "partial contact" preferably means direct contact. In a preferred embodiment, at least one master includes a textured region, which directly contacts the waveguide system. The term "direct contact" means that the rear surface of the master is in physical contact with the waveguide system, and no additional material (layer, air) exists between the waveguide system and the rear surface of the at least one master. In this configuration, the resin can be kept away from the textured region of the master when locally applied to the gap between the at least two masters. By configuring the master with its rear surface facing the waveguide system, the resulting weld seam is in one plane with the rear surface of the master, resulting in a smooth rear surface, which greatly simplifies handling of the extended master, for example, by vacuum clamping. In one embodiment, the light source is a strip of mercury vapor lamps or UV-LEDs arranged in a row or behind a slit curtain, and / or the light from the light source is coupled into the waveguide system via a coupling means. The term "coupling means" refers to, for example, a prism and / or an optical grating. The use of a coupling means makes the position of the light source independent of the position of the waveguide system, thus providing greater freedom in the configuration of different devices. In a preferred embodiment, the light source is positioned laterally of the waveguide system, and light is coupled into the waveguide system from the side of the waveguide system.

[0016] In one embodiment, a force is applied to the at least two masters perpendicularly in at least one of the textured areas. For example, this can be gravity, provided by weight, or a pneumatically controlled force applied to the outer surfaces of the at least two masters not in contact with the waveguide, or alternatively, by using a vacuum passage integrated into the waveguide plate. The force can be 100 N / cm 2 Lower range, preferably 50N / cm 2 is.

[0017] In a preferred embodiment, at least two masters are in direct contact with the waveguide system, with the textured regions facing and in direct contact with the waveguide system. When a force presses the masters against the waveguide system, this increases the coplanarity of the masters within the expanded master. This avoids resin contamination and unwanted lifting of the welded seam, improving the quality of the expanded master.

[0018] In one embodiment, at least two masters are positioned next to each other at a lateral distance of 0-500 μm, taking into account the propagation direction of the waveguide system. The lateral distance between the masters corresponds to the width of the weld seam between the masters in the subsequent extended master. It is conceivable that the distance within the extended master varies between different masters. The distance, and therefore the weld seam, can be used to divide the extended master into different units. The weld seam can also be used as a kind of landmark to detect the position of the extended master during the imprinting process.

[0019] In one embodiment, the positions of the at least two masters, the lateral distance between the at least two masters, the vertical distance between the at least two masters and the waveguide system, and / or the amount of photosensitive resin are detected and / or adjusted by at least one control device. Any type of control device can be used, such as a sensor or a camera, with or without a subsequent evaluation unit (e.g., a computer). Once the positions of the masters are detected, the positions for applying the resin are known, and the resin can be applied to these positions by a resin application device. Additionally, the amount of resin can be controlled and adjusted depending on the lateral distance between the masters. The value of the vertical distance can serve as a measure for the force to be exerted on the masters. Furthermore, the amount of photosensitive resin can serve as a measure for the light intensity coupled into the waveguide system. Furthermore, the measured amounts can be useful for checking the quality of the produced enhanced masters. It is also conceivable to store a limit value, beyond which the initiation of the welding process is prevented. This saves resources and improves the quality of the enhanced masters.

[0020] In one embodiment, the photosensitive resin is applied by lamination and / or dispensing and / or printing and / or capillary forces during the fusing process. Localized application of resin has the advantage that the amount of resin can be well controlled and the backside can be kept clean. On the other hand, applying resin by lamination ensures that the entire volume between the masters is filled with resin without knowing the exact position of the masters.

[0021] In one embodiment, at least one master comprises a material transparent to the light from the light source and acts as an additional waveguide system in addition to the main waveguide system. The additional waveguide system allows the light to be transported particularly efficiently, reducing the amount of loss. Particularly for larger, extended masters made with multiple masters, the additional waveguide system ensures equal light intensity throughout the master structure. Additionally, the additional waveguide system can initiate the curing process before the resin contacts the main waveguide system. This pre-curing method further prevents unwanted spreading of the resin and allows for the creation of better quality seams.

[0022] In a further embodiment, at least two masters and / or the waveguide system have a surface free energy of less than 15 mN / m as measured according to ISO 19403-2:2017. A favorable surface free energy value of the masters and / or the waveguide system further reduces the risk of unwanted spreading of resin, for example, into the textured areas. Additionally, the low surface free energy of the waveguide reduces adhesion between the seam and the waveguide, facilitating removal of the waveguide after the expansion process. In one embodiment of the present invention, the waveguide system comprises, at least in part, a relief structure and / or optical structures and / or doping, for example, as outlined in EP 3256907 A1. In one embodiment, the relief structure corresponds to the relief pattern of at least one master. For example, the relief structure creates a starting area of ​​the imprint stamp and is the area of ​​the stamp where the imprinting process begins. In a further embodiment, the waveguide system comprises, at least in part, an optical structure, and light from the light source is coupled into the waveguide system by the optical structure. The optical structure allows for a free selection of positions for light coupling. In a further embodiment, the wave-guiding system comprises dopings that allow light to exit the wave-guiding system in selected areas. In this embodiment, irradiation can be performed on parts of the master to avoid contamination by uncured resin. The dopings also make it possible to adjust the light intensity of the wave-guiding system. Thus, parts of the wave-guiding system can have a higher light output than other parts and are not affected by contact with the resin.

[0023] In one embodiment, the waveguide system has a sheet shape and / or is at least partially made from glass, fused silica, quartz, a polymer, or a mixture thereof. Alternatively, the entire waveguide system can be made from glass, fused silica, quartz, a polymer, or a mixture thereof, and the waveguide system is preferably made in one piece. In another embodiment, the waveguide system is made from multiple different parts, each made from the same or different materials.

[0024] In a further embodiment of the invention, the waveguide system comprises at least one sensor device, which may be part of the waveguide itself or the device may be separate from the waveguide, which may be connected to a controller unit that controls the amount of photosensitive resin and / or the intensity of the light source and / or adjustments of the master and / or the resin application system.

[0025] Another subject of the present invention is an extended master produced by the method described above. The extended master comprises at least two masters, at least one of which at least partially comprises at least one textured region, with a welded seam (welded region) located between the at least two masters, and the height difference between one textured master and the welded seam is less than 5 μm. This means that the extended master has a uniform height that is not affected or only slightly affected by the welded region (seam). This allows for the production of precise extended masters from multiple masters without the disadvantage of disturbing welded seams between different masters. The resulting extended masters are produced by inexpensive processes, and the dimensions and quantity of the masters can be easily adapted to actual requirements.

[0026] In another embodiment, an extended master is made from one or more masters combined with one or more side tiles to expand the extended master. In a preferred embodiment, a welding seam (welded area) is located between at least one master and one side tile, and the height difference between the master and the welding seam and / or the welding seam and the side tile is less than 5 μm. This has the advantage of creating an area on the outside of the master for collecting resin flow. One or more masters and side tiles may be removed from the extended master. In this embodiment, the welding seam creates a break point within the extended master. The removed textured master can be reused to build the same extended master (in a further welding step) or to build a different extended master. In a preferred embodiment, an extended master made from one or more masters combined with one or more side tiles has an average height difference of less than 5 μm across the entire surface area of ​​the extended master. The side tiles (or frames) are preferably tiles without any product texture, but can have the same master texture or other textures to control resin flow or imprint gap / pressure. Typically, the side tiles are longer than the master tiles in at least one dimension. In this way, the side tiles can facilitate aligning the master tiles to a common reference.

[0027] With regard to lateral tiles, reference is made to (unpublished) European Patent Application No. 20188862.5.

[0028] In one embodiment, an enhanced master is made from multiple masters, and a master may be detached from the enhanced master. Also, in this embodiment, the welded area creates a break point in the enhanced master. The detached master can be used again to build the same enhanced master (in a further welding step) or to build a different enhanced master.

[0029] In another embodiment, the enhanced master has a surface area over which the average height difference is less than 5 μm. This means that the height difference between different masters and between the fused area and the master is less than this value. The resulting enhanced master has a flat surface area, which is particularly advantageous for various applications.

[0030] A further subject of the invention is an imprinted product obtained by an enhanced master produced by the method described above, meaning that the imprinted product is produced via an imprinting process in which the enhanced master is imprinted on a substrate, the enhanced master being produced from at least two masters, at least one of the masters comprising a textured area, and the resulting product at least partially comprising the inverse relief pattern of the textured area.

[0031] A further subject of the invention is an apparatus suitable for producing an enhanced master made according to the above method, the enhanced master being made from at least two masters, at least one of which comprises a textured region.

[0032] The device may include a light source. In an embodiment, the light source is a source of visible light. In an embodiment, the light source is a source of UV light. In an embodiment, the light source is a source of both UV and visible light. In an embodiment, the light source of the device is a strip of mercury lamps or UV-LEDs arranged in a line or behind a slit curtain near the glass edge, and / or the light from the light source is coupled into the waveguide system via a coupling means. The term "coupling means" refers to, for example, a prism and / or an optical grating. The use of a coupling means allows for more efficient internal coupling of light into the waveguide (resulting in higher intensity), which is an advantage. Additionally, the light source can be arranged in various orientations, allowing for greater configuration flexibility. In an embodiment, the light source is positioned laterally of the waveguide system, and light is coupled into the waveguide system from the side of the waveguide system.

[0033] The device may include a waveguide system. In one embodiment, the waveguide system has a sheet shape and / or is at least partially made of glass, fused silica, quartz, a polymer, or a mixture thereof. In an embodiment, the entire waveguide system is made of glass, fused silica, quartz, a polymer, or a mixture thereof, and the waveguide system is made in one piece. In another embodiment, the waveguide system is made of multiple different parts, each part made of the same material or different materials. The multiple parts may be connected with an adhesive having a refractive index that differs from the refractive index of the material of the multiple parts by at most + / - 0.03, preferably at most + / - 0.01.

[0034] In an embodiment, the waveguide system of the apparatus according to the invention comprises a sensor device, which may be part of the waveguide system itself or which may be a separate device from the waveguide system, which may be connected to a controller unit controlling the amount of photosensitive resin and / or the intensity of the light source and / or adjustments of the master and / or the resin application system.

[0035] In a further embodiment, the waveguide system of the device according to the invention at least partially comprises an optical structure, by means of which the light of the light source is coupled into the waveguide system. The optical structure allows the position for light coupling to be freely selected. In a further embodiment, the waveguide system of the device comprises dopings that allow light to exit the waveguide system in selected areas. In this embodiment, irradiation can be performed on parts of the master to avoid contamination by uncured resin. The dopings also make it possible to adjust the light intensity of the waveguide system of the device. Thus, parts of the waveguide system of the device can have a higher light output than other parts and are not affected by contact with the resin.

[0036] In a further embodiment of the invention, the waveguide system comprises at least one sensor device, which may be part of the waveguide itself or the device may be separate from the waveguide, which may be connected to a controller unit that controls the amount of photosensitive resin and / or the intensity of the light source and / or adjustments of the master and / or the resin application system.

[0037] The apparatus may comprise means for applying a force to an outer side of the at least two masters that is not in contact with the waveguide. In an embodiment, the means for applying a force is a weight that can be projected against the at least two masters. In an embodiment, the means for applying a force is a pneumatically or hydraulically driven stamp. In an embodiment, the means for applying a force is a mechanically or electrically driven stamp.

[0038] The apparatus may include a means for applying a photosensitive resin to the at least two masters. In embodiments, the means may be a slot die coater, a screen printer, or possibly a spin coater. In embodiments, the means for applying the photosensitive resin may be a dispensing device that drops or prints liquid resin onto the rear surfaces of the at least two masters. To deposit the photosensitive resin onto the rear surfaces, the dispensing device may be combined with a movable doctor blade or a movable roller. In embodiments, the means for applying the photosensitive resin may be at least one movable nozzle, similar to the nozzle of an inkjet printer, that ejects the photosensitive resin over the entire or localized rear surfaces of the at least two masters. In embodiments, the resin flows over the textured surface by use of capillary forces.

[0039] The apparatus may include a control device suitable for detecting and controlling the positions of the at least two masters, the lateral distance between the at least two masters and the waveguide system, and / or the amount of photosensitive resin. Any type of control device can be used, such as a sensor or a camera, with or without a subsequent evaluation unit (e.g., a computer). Once the positions of the masters are detected, the positions for applying the resin are known, and the resin can be applied to these positions by the resin application means. Additionally, the amount of resin can be controlled and adjusted depending on the lateral distance between the masters. The vertical distance value can serve as a measure for the force that must be applied to the masters by the force application means. Furthermore, the amount of photosensitive resin can serve as a measure for the light intensity coupled into the waveguide system. Furthermore, the measured quantities can be useful for checking the quality of the produced enhanced masters. It is also conceivable to store a limit value, the initiation of the welding process being prevented if this limit value is exceeded. This saves resources and improves the quality of the enhanced masters.

[0040] The apparatus may comprise one or more lifting devices suitable for positioning the at least two masters on a surface of the waveguide system and / or for lifting the expanded master from the surface of the waveguide system. The one or more lifting devices may be one or more robots. The one or more lifting devices may be one or more delta robots. The one or more lifting devices may comprise vacuum chunks for temporary attachment to a smooth surface. The one or more lifting devices may comprise electromagnets for temporary attachment to a ferromagnetic item.

[0041] The apparatus may include a housing that protects the waveguide system, the master, and the surface of the resin from contamination, for example, by dust. The housing may further be opaque to the light used during the curing process to protect personnel from intense light and prevent this type of light from external sources from entering the facility. At least a portion of the housing may be removable, or the housing may include a door for access to the interior of the apparatus. For security reasons, the housing may include a switch that allows the light source to be switched on only when the housing is fully closed.

[0042] The present invention will now be described in more detail with reference to the following figures, the scope of which is not limited by the figures. [Brief explanation of the drawings]

[0043] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a welding method. [Figure 1b] FIG. 10 shows a schematic diagram of a setup for a fusing method using a back plate to stabilize the expanded master and using side tiles. [Figure 2] FIG. 10 shows an image of a portion of an enhanced master with a welded area (welded seam). [Figure 2b] FIG. 10 shows an image of a portion of an enhanced master with a welded area (welded seam). [Figure 3] FIG. 10 shows a schematic 3D representation of a height profile measurement of a fused enhanced master.

[0044] A method for making an enhanced master is shown in Figure 1. In Figure 1, two masters 2, 2' are positioned on and in contact with a waveguide system 5, with the textured regions 4 facing the waveguide system 5. A curable photosensitive resin 3 is present between the two masters 2, 2'. A light source 6 is positioned at the edge region of the waveguide system 5 and guides light within the waveguide system 5. Where the curable photosensitive resin 3 contacts the waveguide system 5, the light exits the waveguide system 5 and hardens the resin 3. The hardened resin welds the masters 2, 2' together by means of a weld seam (the welded region) to form an enhanced master.

[0045] In FIG. 1b, a back plate 8 is attached to the masters 2 and 2′ and the side tiles 9 and 9′. The back plate 8 can be used to stabilize handling. The back plate material can be any sheet, such as a polymer foil, a glass plate, or a metal sheet. Attachment can be performed, for example, using a lamination step in combination with glue, a pressure-sensitive resin, or a curable resin. The side tiles 9 and 9′ can be used to expand a scale-up master. The side tiles 9 and 9′ are attached to the master by a cured resin 3, and further masters are then connected to each other by the same method using a curable resin 3. Here, too, seams are created between the masters and the side tiles, and the height difference between one master and the welded seam is preferably less than 5 μm. In a preferred embodiment, the expanded master (1) made of at least two masters (2, 2′) and at least one side tile (9, 9′) has a height difference of less than 5 μm over the entire surface area. The outer areas of the masters 2 and 2' are available for collecting resin.

[0046] Both Fig. 2 and Fig. 2b show a laser microscope image of the extended master 1. In this image, the two masters 2, 2' are welded together by a weld seam 7. The weld seam 7 is made of hardened resin. The height profile on the right side of Fig. 2 shows that the deviation in height of the weld seam 7 from the plane of the masters 2, 2' is less than 50 nm.

[0047] 3 shows a height profile measurement of two textured masters 2, 2' that have been welded together as described herein. A weld seam 7 is located between the two masters 2, 2', and the height of the weld seam 7 corresponds to the height of the masters 2, 2'.

Claims

1. 1. A welding method for producing an extended master (1) for an imprint process, comprising: at least two masters (2, 2') welded together, at least one master at least partially comprising at least one textured region (4); a photosensitive resin (3) is applied at least between the at least two masters (2, 2'); light from a light source (6) is guided into a wave-guiding system (5), and the difference between the refractive index of the photosensitive resin (3) in its uncured state and the refractive index of a waveguide material of the wave-guiding system (5) is less than 0.2, so that when the photosensitive resin (3) comes into contact with the wave-guiding system (5), total internal reflection of the light in the waveguide material is disrupted, thereby curing the photosensitive resin (3) at least between the at least two masters (2, 2').

2. 2. The welding method according to claim 1, wherein the at least two masters are positioned such that the textured region (4) of the at least one master is oriented towards the wave-guiding system (5) and / or at least one of the masters is at least partially in contact with the wave-guiding system (5).

3. 3. The welding method according to claim 1 or 2, wherein the light source (6) is a mercury lamp or a strip of UV-LEDs and / or the light of the light source (6) is coupled into the wave-guiding system (5) via coupling means.

4. 4. The welding method according to any one of claims 1 to 3, wherein the at least two masters (2, 2') are subjected to a normal force in at least one of the textured areas (4).

5. 5. The welding method according to claim 1, wherein the at least two masters (2, 2') are positioned next to each other at a lateral distance of 0 to 500 μm.

6. 6. The welding method according to claim 1, wherein the positions of the at least two masters (2, 2'), the lateral distance between the at least two masters (2, 2'), the vertical distance between the at least two masters (2, 2') and the wave-guiding system (5), and / or the amount of the photosensitive resin (3) are detected and / or adjusted by at least one control device.

7. 7. The welding method according to claim 1, wherein the photosensitive resin (3) is applied by laminating and / or dispensing and / or printing and / or capillary forces.

8. 8. The welding method according to any one of claims 1 to 7, wherein at least one master comprises a material transparent to the light from the light source (6) and acts as a further waveguiding system.

9. 9. The welding method according to claim 1, wherein the at least two masters (2, 2') and / or the waveguide system (5) have a surface free energy of less than 15 mN / m, measured by contact angle measurement according to ISO 19403-2:2017.

10. 10. The deposition method according to any one of the preceding claims, wherein the waveguiding system (5) at least partially comprises a relief structure and / or an optical structure and / or a doping.

11. 11. The deposition method according to any one of the preceding claims, wherein the waveguide system (5) has a sheet shape and / or is at least partially made of glass, fused silica, quartz, a polymer, or a mixture thereof.

12. 12. The welding method according to any one of the preceding claims, wherein the wave-guiding system (5) comprises at least one sensor device.

13. 13. An expanded master (1) produced by the welding method according to any one of claims 1 to 12, wherein the expanded master comprises at least two masters (2, 2'), at least one of which at least partially comprises at least one textured region (4), and a welding seam (7) is located between the at least two masters, and the height difference between one textured master and the welding seam (7) is less than 5 μm.

14. The expanded master (1) according to claim 13, wherein the expanded master (1) comprises at least one lateral tile (9).

15. 15. The enhanced master (1) according to claim 13 or 14, wherein the enhanced master (1) has a surface area, the average height difference over the entire surface area being less than 5 μm.

16. An imprinted product made with the enhanced master (1) according to claim 13.

17. Apparatus for producing an extended master by carrying out the deposition method according to any one of claims 1 to 12.

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