Apparatus for roll-to-plate imprint process having a plate carrier with cavities

Abstract

The present invention relates to an imprinting apparatus for a roll-to-plate process, comprising a flexible master with an imprint pattern, a plate carrier, a substrate, and a curable imprint resin. The substrate is disposed on the plate carrier. The flexible master supports the inverse structure (imprint pattern) required for the desired product. The curable resin (also called lacquer) is disposed on the substrate and / or the flexible master. During the imprinting process, the flexible master is pressed onto the substrate with the curable resin sandwiched between them. The plate carrier has a cavity. The substrate is disposed within the cavity. At least one side of the substrate is at least partially uncovered by the cavity. Another aspect of the present invention relates to two roll-to-plate processes.

Description

[Technical field]

[0001] Imprinting devices for roll-to-plate processes are known and comprise a roller, a flexible master with an imprint pattern, a plate carrier, a substrate and a curable imprint resin. The substrate is placed on the carrier material. The flexible master carries the inverse structure (imprint pattern) required for the desired product. The curable resin (also called lacquer) is placed on the substrate and / or on the flexible master. During the imprinting process, the flexible master is pressed onto the substrate with the roller, sandwiching the curable resin between them. After curing, the resin is solidified, for example by heat and / or UV, and the flexible master is removed, resulting in textured areas on the substrate.

[0002] Known prior art roll-to-plate imprint apparatus are described, for example, in WO 2016 / 128493.

[0003] US 2016 / 257062 discloses an imprinting apparatus in which a flexible mold is held by vacuum on a surrounding stage and pressed onto a substrate having a curable resin (see FIG. 1), thereby achieving a uniform imprint regardless of the thickness of the substrate. The patent also discloses a plate on the stage that forms a type of cavity.

[0004] JP 2016 / 197672 A discloses an imprinting apparatus and an imprinting method for preventing resin from flowing. A substrate is positioned on a stage, and an elastic member is disposed on the stage to form a gap portion. The gap portion surrounds the substrate, and according to FIG. 1, the substrate is embedded in an elastic material (the elastic member is formed around the substrate).

[0005] The imprint quality and residual layer thickness of the textured areas on the substrate depend on the process settings such as imprint speed and imprint pressure. To obtain a thin residual layer, a high imprint pressure is applied to the roller. This imprint pressure is applied on both sides of the roller. Due to the discontinuous nature of the process and having a linear pressure, it is difficult to achieve a uniform imprint pressure over the entire substrate area to be imprinted. The non-uniform pressure of the roller affects the pressure of the flexible master on the curable material of the substrate, resulting in variation in the properties of the resulting product. For wafer-scale imprint processes, this uniformity issue is solved by full surface imprint or a variable well-controlled pressure over the imprint area with a flat substrate and mask holder (chuck). The roll-to-roll replication process is a continuous process over a rectangular surface.

[0006] In particular, there are two main process situations that cause uneven pressure. With the substrate placed on the carrier, the roller has transition areas at the initial and final contact points with the substrate. The roller pressure is applied and divided across the lower carrier surface and the higher substrate surface. This results in higher imprint pressure at the beginning and end of the substrate, especially for thicker substrates. -If the substrate has a variable width, the linear pressure per unit area of ​​the imprint roller varies on the substrate. The variation in width results in the same linear pressure being applied over a wider or narrower area.

[0007] Therefore, it is generally difficult to apply uniform pressure over the entire area of ​​the substrate by using such roll-to-plate apparatus.

[0008] It is therefore an object of the present invention to compensate or at least minimize the drawbacks of prior art roll-to-plate imprinting devices, while at the same time preferably not affecting the processing characteristics (e.g. substrate insertion) and the error rate during the process.

[0009] This object is achieved by an imprint apparatus for a roll-to-plate process, wherein the plate carrier has at least one cavity in which a substrate can be placed, and wherein at least one side of the substrate is not at least partially surrounded by the cavity.

[0010] At least one side indicates that for a rectangular shape of the substrate, at least one side of the substrate is at least partially not surrounded by a cavity. When a rectangular substrate is used, preferably two sides are not surrounded, most preferably two sides arranged opposite each other. Preferably, the side not surrounded or both sides not surrounded are in the imprint direction. When a circular substrate is used, the substrate has only one side that is at least partially not surrounded by a cavity. The term "at least partially not surrounded" means that at least 5%, more preferably at least 20%, most preferably at least 50% of the side is not surrounded by a cavity. For a rectangular substrate, preferably 10%, more preferably 50%, most preferably 100% of one side is not surrounded by a cavity.

[0011] The term "unenclosed" means that there are no cavity side walls. Cavities having larger dimensions than the substrate, whereby there is a small gap between the cavity side walls and the substrate, ensuring easy placement of the substrate in the cavity, should not be understood by the term "unenclosed". Such gaps for easy handling may have a width of tens to hundreds of micrometers.

[0012] A cavity that does not completely surround the substrate allows the contact of the flexible master with the plate carrier and the substrate to be constant during the imprint process. When pressure is applied to the side of the roller to press the flexible master onto the substrate, this pressure is distributed over the length of the roller in contact with the substrate. This means, for example, that for a circular substrate, the pressure is higher at the beginning and end. If a circular substrate is placed in a circular cavity, the pressure is distributed evenly over the substrate and the cavity sides. This is amplified if the cavity sides have the same height as the substrate and the total length of contact of the roller on the substrate and the carrier plate is always the same. However, the carrier plate does not need to be completely enclosed, but may have openings and may have different shapes compared to the shape of the substrate. Thus, the substrate shape becomes more independent of the cavity shape, and thus the cavity is designed as claimed in the present invention.

[0013] Furthermore, the fact that the cavity does not completely surround the substrate creates a kind of outward flow: excess uncured resin is able to escape during the imprint process and does not flow onto the substrate.

[0014] Furthermore, the fact that the substrate is not completely surrounded by the cavity creates a passageway to the substrate. This passageway can be used to reduce the effect of oxygen inhibition of the acrylate resin, which results in a resin that is not completely cured. This oxygen inhibition occurs when the resin is exposed to oxygen while being cured by UV light. The resin remains sticky at the surface, which is undesirable for handling and downstream process steps. The open area of ​​the cavity that forms the passageway to the substrate can reduce this effect of gas insertion into the substrate, for example by replacing oxygen with nitrogen or another inert gas. The substrate is then surrounded by, for example, nitrogen that is inserted through the passageway. In this case, the resin that is not completely trapped between the substrate and the flexible stamp during the resin and curing step is also completely cured.

[0015] Another advantage of the cavities is that along the roller perpendicular to the imprint direction the total length of the contact area between the roller, the substrate and the carrier plate is always equal and independent of the substrate design.

[0016] At least one substrate can be disposed within the at least one cavity. If the substrate has more than one cavity, each cavity can have one or more substrates.

[0017] At least one cavity means that the plate carrier may have two or more cavities, however, in the following the term "cavity" will be used even if multiple cavities are included.

[0018] The plate carrier according to the present invention is a kind of plate having a carrier surface, the area of ​​the carrier surface is greater than the thickness of the plate perpendicular to the carrier surface, and the width and length of the plate carrier are greater than the area of ​​the substrate.

[0019] The substrate also has a substrate surface perpendicular to the substrate surface, which is greater than the thickness of the substrate. The substrate has two substrate surfaces, which are parallel to each other and arranged one above the other. Perpendicular to the substrate surface, the substrate has a side surface. The curable lacquer is present on one substrate surface.

[0020] The term "flexible master" is used for any device that is flexible and suitable as a carrier for the imprint pattern. Preferably, the flexible master is a flexible stamp or a flexible nickel shim.

[0021] The term "cavity" refers to any particular reduction or elevation of at least one segment of the plate carrier that forms a storage area for substrates on the plate carrier. Cavities include, for example, recesses in the plate carrier having one or more side walls (see FIG. 6B) as well as gaps in the plate carrier in the form of grooves (see FIG. 7). A storage area is a portion of the plate carrier where substrates are located on or within the plate carrier.

[0022] At least one cavity guides the roller with the flexible master (and the inverse imprint pattern) over the substrate while the roller and the edge of the flexible master move on the plate carrier, such that the pressure of the flexible master on the substrate is evenly distributed across the substrate.

[0023] It will be clear that on top of the substrate surface (or on top of the flexible master) there is a hardenable resin (also called lacquer) and the flexible master prints structures into this lacquer, resulting in a (reverse) imprint pattern on the substrate. In the following, when it is mentioned that the flexible master is in contact with the substrate, this means that the inverse imprint pattern of the flexible master is transferred into the resin between the flexible stamp and the substrate. For the imprint process and other apparatus means of the imprint apparatus, reference is made to WO 2018 / 011208.

[0024] In a preferred embodiment, the cavities have a height approximately equal to the substrate thickness (see FIG. 5). In another preferred embodiment, at least one cavity has a height approximately equal to the substrate thickness plus the thickness of the curable resin on the substrate. The term "equal" means that the height of the cavity differs from the substrate thickness by less than 200 μm, preferably less than 100 μm, more preferably less than 50 μm, and most preferably less than 20 μm. However, during the imprinting process, the substrate has a spreading direction relative to the position of the roller, and the thickness of the substrate is perpendicular to the spreading direction. However, this means that the substrate has a surface area to be imprinted, and the thickness of the substrate is perpendicular to the imprinting surface. In this preferred embodiment, the surface of the flexible master contacts the substrate and the raised side of the plate carrier, thereby ensuring a constant pressure on the substrate.

[0025] In a preferred embodiment, the cavity has one or more side walls, the side walls having a height approximately equal to the sum of the thickness of the substrate and the thickness of the flexible master containing the imprint pattern. Also in this embodiment, the flexible master with the inverse imprint pattern has a maximum width equal to that of the substrate, which ensures that it does not contact the raised sides of the plate carrier and ensures a constant pressure across the contact area. In a preferred embodiment, the width of the imprint pattern is smaller than the width of the cavity.

[0026] In both of the above mentioned embodiments, full surface contact with constant pressure across the contact area between the substrate and the flexible master significantly improves the imprint results, and thus the resulting product has higher product quality and better controlled layer thickness uniformity.

[0027] In a preferred embodiment, the plate carrier comprises a compensation material. Preferably, the compensation material is an additional layer of a fluid (such as a gas or liquid) or flexible material. The plate carrier is preferably formed primarily of a material that is not flexible, such as glass, and thus the additional compensation material is added.

[0028] The term "compensation material" refers to any material that has reversible pressure compensation properties. In a preferred embodiment, the compensation material is a fluid. Preferably, the fluid is present in the form of an additional layer that is in direct conformal contact with the plate carrier. The term "direct contact" means that the additional layer is in mechanical contact with the plate carrier. For example, the additional layer is disposed between the substrate and the plate carrier. In a preferred embodiment, the fluid is a gas or a liquid. Gases include argon, nitrogen or air. Water, oil, acrylate fluids or curable acrylate fluids are preferred liquid media. In a further preferred embodiment, the fluid is a viscoelastic fluid. Preferably, the plate carrier has a fluid system that allows the fluid to be poured into the additional layer (like a cushion for the substrate).

[0029] In another preferred embodiment, the compensation material is a flexible material. The term "flexible" means that the material can be compressed reversibly. The material can be easily folded without breaking. This means that the flexible material is elastic compared to glass or metal. Preferably, the flexible material has a Young's modulus between 0.1 gigapascals (GPa) and 10 gigapascals (GPa), more preferably between 0.5 gigapascals and 5 gigapascals, measured according to ASTM E111. By way of example, the flexible material may be rubber, elastomer, fiber material, EPDM, polychloroprene, polyurethane or another plastic or a mixture of the above-mentioned materials. In this application, if the material has a Young's modulus of more than 50 GPa measured according to ASTM E111, it is called a rigid material.

[0030] In a more preferred embodiment, the compensation material has a Shore A value of less than 80 Shore A measured according to ASTM D2240.

[0031] In a preferred embodiment, the plate carrier and the cavities are formed as one piece, i.e. from one part. This means that at least one cavity is part of the plate carrier and is formed by removing material of the plate carrier. The one-piece embodiment has the advantage that no collection of contamination in the seams of the plate carrier is possible.

[0032] Preferably, the cavity is arranged in the compensation material. In this preferred embodiment, the cavity is a recess in the compensation material. In one preferred embodiment, the cavity is part of the compensation material. The compensation material, for example a flexible mat, is also preferably placed in the cavity of the plate carrier. The flexible mat extends over or is defined by the cavity. In this embodiment, the plate carrier may be made of a rigid material and the compensation material is a flexible mat. If a fluid is used as the compensation material, the substrate is arranged above a gas or liquid bed. It is preferred that the plate carrier has a fluid flow system for forming a gas or liquid bed in the cavity or that the cavity itself has a fluid flow system. In both embodiments, the plate carrier may be present in the first plate carrier part and in the second plate carrier part.

[0033] In the roll-to-plate imprint process, large surface areas of the substrate can be imprinted. This large surface can only be transported by using a large plate carrier. The larger the plate carrier size, the more complex the formation of a flat surface of the plate carrier becomes. If the plate carrier is not perfectly flat, the pressure on the substrate placed on top of it will be locally different. As a result, local thickness variations will occur in the final product. Moreover, if the back surface of the (large) substrate in contact with the plate carrier is not uniformly flat due to thickness variations, defects or contamination (e.g. dust particles), pressure variations during imprinting will also occur. Furthermore, non-uniformity of the imprint roller will cause pressure variations during the imprint process. All this leads to locally thinner or thicker residual layer thicknesses. Thus, a non-uniform back surface of the substrate will cause visible defects on the front surface of the substrate (this means the lacquer side), affecting the quality of the imprinted final product. The unevenness is compensated by the use of compensation materials (e.g. flexible materials).

[0034] In another preferred embodiment, the plate carrier is formed from at least two parts. Preferably, at least one of the two parts of the plate carrier is formed from or forms a compensation material. For example, the plate carrier may have a non-flexible material (glass) as a first part and a flexible material (as an embodiment of a compensation material) as a second part. In another example, the first plate carrier part has a fluid flow system for forming a gas or liquid bed as a compensation material, and the second plate carrier part of the plate carrier is formed from a rigid or flexible material forming a cavity. The cavity may be part of the first part or part of the second part, or may extend over both parts. Preferably, the plate carrier is formed from a first part of a glass or metal material, and the second plate carrier part is formed from a flexible material. The cavity is part of the second part. As an example, the cavity is completely embedded in the flexible material of the second plate carrier part of the plate carrier. In another example, the second plate carrier part includes a fluid flow system, which is preferably disposed in the cavity. Also, in this embodiment, the first plate carrier part and the second plate carrier part are made of the same or different materials. By using two parts, both parts may be made of different materials, and the stability of the plate carrier is not reduced even when the flexibility is increased.

[0035] Preferably, at least two parts of the plate carrier are reversibly connectable to each other. "Reversibly connectable" means that both parts can be separated from each other without either of them being destroyed. The connection between both parts can be achieved via adhesive surfaces on one or both parts, via adhesive and / or by plug connections (like rail systems or locating pins) and / or by screw systems and / or magnetically, or by a combination of the above mentioned systems. The two-part construction of the plate carrier makes it easy to adapt the plate carrier to different substrate thicknesses (lacquer thicknesses) or flexible master thicknesses. Furthermore, by using compensation material as one part, this part has a higher wear resistance than a part made of non-flexible material. Therefore, only a part of the plate carrier (instead of the whole plate carrier) has to be replaced.

[0036] Preferably, the flexible material is a rubber or plastic film. As an example, the flexible material may be rubber, an elastomer, a textile material, EPDM, polychloroprene, polyurethane or another plastic or a mixture of the above mentioned materials.

[0037] In a preferred embodiment, a vacuum system is arranged in the cavity of the plate carrier. The cavity may have, for example, a vacuum hole through which a lower pressure can be created in the cavity. This holds the substrate in a defined position in the cavity, thus improving the imprint process. A vacuum hole is not equivalent to a fluid flow system. A vacuum hole creates a kind of negative pressure (to hold the substrate in place), whereas a fluid flow system creates a kind of fluid bed for the substrate.

[0038] In a further preferred embodiment, the plate carrier comprises a positioning system, which preferably comprises lifting fingers, by means of which the substrate can be easily positioned on the carrier plate, for example by using a robot. In another preferred embodiment, the carrier comprises positioning pins (also called alignment pins or pushers) for positioning, by means of which the substrate can be positioned in a preferred position or always in the same position relative to a reference point. As a result, the imprint process always starts at the same point on the substrate, which advantageously increases the process accuracy.

[0039] In a preferred embodiment, the cavity is equal to the shape of the substrate. "Equal to the shape" in this context means that the cavity is not circular, for example that the substrate is angular. Advantageously, one or more side walls of the cavity form a kind of pocket into which the substrate can be inserted. In this embodiment, the substrate is protected at selected sides of the substrate by the plate carrier during the imprinting process. It is also possible to dimension the cavity such that the substrate sits in the plate carrier in a form-fitting manner, thus avoiding slippage during the imprinting process. However, it is also conceivable that the cavity is formed as a kind of wide groove that runs over the entire plate carrier. Thereby, the cavity opening (the unenclosed part of the substrate side) coincides with the imprinting direction or a direction perpendicular to the imprinting direction. Furthermore, a combination of both can form a rectangular inner cavity.

[0040] In another preferred embodiment, the cavity has a raised sidewall edge, meaning that the height of at least one sidewall edge of the cavity is increased at the edge of the substrate, whereby the roller is raised at the end of the imprint process, reducing the imprint pressure and thus preventing or reducing overflow of the lacquer at the edge of the substrate. In a more preferred embodiment, the substrate has two raised sidewalls.

[0041] In another preferred embodiment, a film is placed on the plate carrier and extends into the cavity. A substrate is placed on the film within the cavity. The film protects the plate carrier and the cavity from contamination and / or prevents the substrate from slipping during processing and / or affects the refractive index of the substrate.

[0042] Yet another concept relates to a roll-to-plate process in which a substrate is placed in a cavity of a plate carrier and a flexible master with an inverse structure is pressed onto the substrate, the height of the cavity being adapted to match the height of the substrate and / or the height of the flexible master and the substrate, and the substrate is placed in the cavity such that at least one substrate side is at least partially not surrounded by the cavity.

[0043] All embodiments mentioned for the imprint apparatus are also applicable to the roll-to-plate process.

[0044] In the following, the concept of the invention is explained further with reference to the drawings. [Brief description of the drawings]

[0045] [Figure 1] FIG. 2 illustrates a schematic diagram of an imprint process; [Diagram 2] FIG. 13 shows the measured correlation between imprint pressure and layer thickness. [Diagram 3]FIG. 13 illustrates a schematic of one example of varying substrate width that can result in varying imprint pressure. [Figure 4] FIG. 13 is a schematic diagram illustrating the imprint pressure at the center compared to the pressure at the edge of a substrate. [Diagram 5] FIG. 2 is a schematic diagram of a plate carrier having a cavity. [Figure 6] FIG. 2 is a schematic diagram of a plate carrier having a pocket-shaped cavity. [Figure 6B] FIG. 2 is a schematic diagram of a plate carrier having a pocket-shaped cavity with raised sidewall edges. [Figure 7A] FIG. 2 is a schematic diagram of a plate carrier having a circular cavity. [Figure 7B] FIG. 2 shows a schematic diagram of a plate carrier having two circular cavities. [Figure 8] FIG. 2 is a schematic diagram of a plate carrier having a first portion and a second portion. [Figure 9] FIG. 13 is a schematic diagram of a plate carrier having a flexible material.

[0046] FIG. 1 shows the imprinting arrangement and the imprinting process related to the present invention. A flexible master 105 with an imprint pattern 105A with a reverse structure (negative) 105A as required for the product is pressed into a hardenable resin 102 on a substrate 101 using a roller 104. The substrate 101 is a plate made, for example but not limited to, of rigid glass and may have different shapes. The substrate 101 is placed on a plate carrier 100 for applying counter pressure and possibly for transport. The plate carrier 100 may be made of glass or metal, among others. After hardening the hardenable resin 102 (lacquer) by using UV light 107A from a UV light source 107, the flexible master 105 is removed and the hardened resin 102 with the required product texture 106B and the residual layer 106A below it has been transferred onto the substrate 101.

[0047] The height of the curable resin 102 depends, among other things, on the imprint pressure. This height is the sum of the product texture 106B and the residual layer 106A. The residual layer 106A has the same texture height independent of the imprint pressure. The thickness of the residual layer 106B decreases as the imprint pressure increases. This correlation is shown in FIG. 2. Apart from the imprint pressure, the residual layer thickness also depends on the imprint speed and the viscosity of the resin. In FIG. 2, the correlation between the imprint pressure and the layer thickness (residual layer and product texture) is shown for two different resin viscosities imprinted at a speed of 3.49 cm / min. FIG. 2 shows that when the imprint pressure is increased from 10 N / cm to 20 N / cm, the layer thickness decreases from about 5.5 micrometers to 4 micrometers for a standard resin viscosity of 330 cP.

[0048] In the roll-to-plate imprint process, the roller 104 is large compared to the substrate size, as shown in Figure 3. The imprint roller force Fr is applied at the side (edge) of the roller 104. For a rigid roller, this * F r The total force of is divided equally on the imprint contact area. For small substrate 101 widths, the linear pressure (per unit or per cm) 108A is higher compared to wider substrate widths causing a lower linear pressure 108B. Due to this pressure variation on the substrate 101, the imprint pattern 105A of the flexible master 105 is not replicated uniformly in the lacquer on the substrate 101. The thickness of the residual layer will vary or even air bubbles will be trapped.

[0049] 4 shows the varying imprint pressure at the rear of the imprint process at the edge of the substrate 101. A similar problem occurs at the front of the imprint process at the front of the substrate. In both the front or rear situations, the roller 104 exerts a roller force F on the substrate 101 with the flexible master 105 in between. rThe roller 104 has a rigid core 104A and a softer, compressible outer layer 104B. Due to the soft outer layer, the roller 104 is compressed by the roller pressure and the roller contact surface 109A is enlarged. This roller contact surface 109A on the substrate 101 is smaller than if the roll 104 was pressed at the rear of the substrate 101 onto the roller contact surface 109B. In this case, the force remains the same but is transferred to a smaller contact area of ​​the substrate 101. The smaller the roller contact surface 109A, the greater the linear pressure and the smaller the residual layer thickness.

[0050] To address the varying pressure at the front and rear of the substrate 101 and with the change in substrate width, it is proposed that the plate carrier 100 includes a cavity. This is shown in FIG. 5, where the plate carrier 100 has two raised side walls 112 forming a cavity 110 inside which the substrate 101 is placed. With the raised carrier side walls at the front and / or rear of the substrate 101, the pressure is more evenly distributed when the roller transitions from the raised carrier side walls to the front and / or rear of the substrate 101 during the start and end of the imprint process. This makes the pressure uniform over the start and / or end of the imprint process. It is noted that already one raised side wall at the front or rear of the substrate is beneficial to create a uniform pressure at the start or end of the imprint process. The cavity height 110B has a height difference compared to the substrate thickness of preferably less than 200 micrometers, more preferably less than 100 micrometers, and most preferably less than 50 micrometers. The cavity 110 does not completely surround the substrate 101. According to the embodiment of FIG. 5, two sides of the substrate 101 are not surrounded by the cavity 110. The cavity 110 has an open area, in which at least one side of the substrate 101 is not at least partially surrounded by the cavity 110. This makes it easier to insert or remove the substrate 101 into the cavity 110. Furthermore, one and the same cavity 110 can be used for rectangular substrates with different widths without any quality loss during the imprint process. If the cavity 110 does not completely surround the substrate 101, the shape of the cavity 110 becomes more independent. In one embodiment, the material of the raised sidewall 112 and / or the plate carrier 100 is a compensation material. The compensation material may be a flexible material or a fluid material. In case of a fluid material, the plate carrier 100 is preferably integrated with an air flow system or a liquid flow system.In a preferred embodiment, the raised sidewalls 112 are designed to be removably disposed on and connectable to the substrate 101. The substrate 101 and the raised sidewalls 112 together form a more uniform support.

[0051] Preferably, the substrate 101 is placed as close as possible to one or more side walls 112 in juxtaposition. Preferably, the substrate 101 is in direct contact with at least one side wall 112. If two side walls 112 are used, the cavity length preferably has the same length as the substrate 101, with a small excess to allow the substrate 101 to be placed thereon. This difference between the cavity length and the substrate length is preferably less than 1 mm, more preferably less than 500 micrometers, and most preferably less than 200 micrometers. In any of these cases, the cavity length is longer than the substrate length.

[0052] The width of the roller 104 is typically larger than the substrate 101. Therefore, the cavity 110 present in the two side walls 112 can also be rotated 90 degrees as shown in FIG. 5. This is shown in FIG. 6. Due to the raised sides 112 of the carrier 100, the imprint gap is constant during the imprint process. The length of the side walls 112 is preferably longer than the length of the substrate 101, and preferably the substrate 101 is located in the center of the side walls 112. The imprint step at the beginning and end of the substrate 101 is significantly reduced. For a substrate 101 with a constant width, this results in a uniform pressure over the entire imprint area including the beginning and end of the substrate 101. It should be noted that due to the soft roller 104, there is a small imprint step. This small imprint step can also be compensated by using the side walls 112 at the front and rear of the substrate 101. If the width of the flexible master 105 is larger than the width of the cavity 110, the cavity height 110B may be the same as the substrate thickness (substrate height), preferably with a variation of less than 200 micrometers, more preferably less than 100 micrometers, and most preferably less than 50 micrometers. If the width of the flexible master 105 is smaller than the width of the cavity 110 and positioned in the cavity 110, the cavity height 110B should be the same as the sum of the thickness of the substrate 101 and the thickness of the flexible master 105. It should be noted that in the imprint process shown in both Figures 5 and 6 and 6B, more substrates can be imprinted in the same imprint cycle. If the cavity 110 is wide enough or long enough, multiple substrates can be placed side by side. In this case, the width of the roller 104 must be larger than the cavity 110. The flexible stamp should cover at least two substrates. The flexible stamp 105 may have multiple imprint patterns 105A aligned with locations on the substrate 101. Alternatively, the flexible stamp may have one large imprint pattern 105A covering the substrate location 101.

[0053] FIG. 6B shows a similar imprint configuration. At the end of the imprint process, the height of the raised sidewall end 113, which is usually located on the sidewall 112 of the plate carrier 100 near the rear of the substrate 101, is increased by a bumb. This bumb results in a higher cavity height 110B. This higher imprint gap reduces the pressure at the end of the imprint process. The low imprint pressure at the end prevents resin spillage. Such a bumb can further ensure that the resin spillage is kept in the substrate plane and does not contaminate the plate carrier 100. The sidewall end 113 does not necessarily have to be located at the rear of the sidewall 112. The positioning depends on the position of the substrate 101 and the end of the imprint process. Thus, the sidewall end 113 can also be located in the center of the plate carrier 110. The sidewall end 113 may have different shapes. According to FIG. 6B, the sidewall end has a wedge shape. However, a block shape, a bridge shape or a ski-jump shape is also suitable.

[0054] For substrates with varying widths, the pressure can be made uniform by adapting the cavity 110 to the shape of the substrate 101. An example is shown in FIG. 7A, which shows a circular cavity 110 suitable for imprinting on a circular substrate 101. In practice, the cavity 110 is slightly wider to ensure easy loading and removal of the plate carrier 100. The margin in width is preferably less than 2 mm (1 mm on each side), more preferably less than 1 mm, and most preferably less than 400 micrometers. The cavity height 110B is the same as the substrate height. The cavity 110 has a kind of groove, which in the embodiment shown in FIG. 7A runs in the imprint direction. Due to this groove, the circular substrate part is not surrounded by the cavity 110. The groove allows the substrate to be easily loaded and removed. In addition, a type of liquid can flow along the grooves to support the substrate 101 during the imprint process or to support handling features for the insertion or removal of the substrate 101. Note that in FIG. 7A, one cavity is shown. However, there may be multiple cavities, as shown in FIG. 7B. By using a larger imprint system and a larger flexible stamp, two or more substrates 101 can be imprinted in the same imprint cycle. This increases the throughput. In this case, the flexible stamp 105 should have multiple imprint patterns 105A and 105B. The positions of these imprint patterns 105A, 105B are aligned with the positions of the substrate 101 in the carrier 100. The flexible stamp 105 may have one large imprint pattern that covers both substrate 101 positions on the carrier 100.

[0055] FIG. 8 shows a plate carrier 100 formed from a first plate carrier part 100A and a second plate carrier part 100B. The second plate carrier part 100B has a cavity 110. The first plate carrier part 100A and the second plate carrier part 100B are reversibly connectable to each other. This allows a variable cavity height 110B to be formed, and allows the same base carrier material (first part 100A) to be used for different substrate heights. The materials of the first plate carrier part 100A and the second plate carrier part 100B can be the same or different from each other. For example, the material can be a glass or metal layer. The second plate carrier part 100B can be attached, for example, by using a protruding locating pin on the first plate carrier part 100A and a locating hole in the second plate carrier part 100B.

[0056] In a preferred embodiment, the plate carrier 100 shown in FIG. 8 has a first plate carrier part 100A that is rigid and a second plate carrier part 100B that is flexible as a compensation material. As an example, the second plate carrier part 100B may be made of rubber or plastic sheet. If the back surface of the substrate 101 is not uniformly flat due to defects or thickness variations, pressure variations occur during imprinting. This causes a locally thin residual layer thickness of the resin 102. A non-uniform residual layer is found at the front surface of the imprinted product. With the second plate carrier part 100B made of a flexible material, this effect can be avoided or reduced. In a second example, the first plate carrier 100A has an integrated fluid flow system to form an air layer by using an air flow system or a liquid bed by using a liquid flow system (compensation material). An air or liquid cushion (not shown in FIG. 8) under the substrate 101 serves as a non-uniform compensation layer.

[0057] In Fig. 9, the plate carrier 100 has a cavity 110. An exemplary flexible material 111 for compensation material is disposed inside the cavity 110 and on the top side of the plate carrier 100. The use of the flexible material 111 can prevent or reduce the effect of imperfections or non-uniformity in layer thickness under the substrate 100 that cause pressure variations and thus imprint variations.

Claims

1. An imprinting apparatus for a roll-to-plate process having a flexible master (105), a plate carrier (100) and a substrate (100), wherein the flexible master (105) can be pressed onto the substrate (100) during an imprinting process, the plate carrier (100) having at least one substrate (101), the plate carrier (100) having at least one cavity (110) in which the at least one substrate (101) is arranged, An imprinting apparatus, characterized in that at least one substrate side is at least partially not surrounded by said cavity (110).

2. The imprinting apparatus of claim 1 , wherein the at least one cavity (110) has a height (110A) approximately equal to the sum of a thickness of the substrate (101) and a thickness of the curable resin (102) on the substrate (101).

3. The imprinting apparatus of claim 1 , wherein the at least one cavity (110) has a height (110A) approximately equal to or less than a sum of a thickness of the substrate and a thickness of the flexible master (105).

4. The imprinting apparatus according to any one of the preceding claims, wherein the plate carrier (100) comprises a compensation material (111).

5. The imprinting apparatus of claim 4 , wherein the cavity (110) is disposed within the compensation material (111) or the compensation material (111) is disposed within the at least one cavity.

6. The imprinting apparatus of any one of the preceding claims, wherein the plate carrier (100) and the cavity (110) are formed from one piece.

7. The imprinting apparatus according to any one of the preceding claims, wherein the plate carrier (100) is formed from at least two parts (100A, 100B).

8. The imprinting apparatus of claim 7 , wherein the at least two parts (100A, 100B) of the plate carrier (100) are reversibly connectable to each other.

9. The imprinting apparatus of claim 7, wherein at least one of the two parts (100A, 100B) of the plate carrier (100) is made from a compensation material (111).

10. 5. The imprinting apparatus of claim 4, wherein the compensation material is a flexible material (111), the flexible material having a Young's modulus, measured according to ASTM E111, between 0.1 and 10 gigapascals (GPa), particularly preferably between 0.5 and 5 gigapascals (GPa).

11. The imprinting apparatus of any one of the preceding claims, wherein a fluid flow system is arranged in the cavity (110) of the plate carrier (100).

12. The imprinting apparatus according to any one of the preceding claims, wherein the plate carrier (100) comprises a positioning system for the substrate (101).

13. The imprinting apparatus of any one of the preceding claims, wherein a shape of the cavity (110) is equal to a shape of the substrate (101).

14. The imprinting apparatus according to any one of claims 1 to 13, wherein the substrate (101) and / or the plate carrier (100) have at least one raised sidewall (112), the at least one raised sidewall (112) having a raised sidewall end (113).

15. A roll-to-plate process, comprising placing a substrate (101) in a cavity (110) of the substrate (101) and pressing a flexible master (105) onto the substrate (101) such that a cavity height (110B) is adapted to match the height of the substrate (101) and / or the height of the flexible master (105) integrated with the height of the substrate, and placing the substrate (101) in the cavity (110) such that at least one substrate side of the substrate is not at least partially surrounded by the cavity (110).

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