Method and system for in-situ layer thickness control during imprinting

Abstract

This invention relates to a method and system for in-situ layer thickness control during imprinting (particularly nanoimprinting), which enables control over the residual layer thickness of the imprinted product. The method includes the steps of: providing a substrate, a substantially flexible stamp, and rollers configured to apply pressure to the flexible stamp and / or the substrate; applying resin to the stamp and / or the substrate; imprinting; curing; and separating the flexible stamp and the substrate, wherein the method provides control over the residual layer thickness.

Description

[0001] This invention relates to a method for in-situ layer thickness control during imprinting (particularly nanoimprinting). The invention also relates to a system for in-situ layer thickness control during imprinting (particularly nanoimprinting).

[0002] Residual layer thickness (RLT) and its variation are important parameters for textured surfaces obtained through imprinting, particularly nanoimprinting. The thickness of the residual layer existing between the imprinted texture and the substrate affects the efficiency of devices using the desired texture, and variations in RLT lead to optical changes across the entire device. Furthermore, variations in RLT affect the settings to be used in post-processing of the imprinted substrate, such as etching. Therefore, it is desirable to efficiently achieve the desired residual layer thickness and keep it as constant as possible throughout the production line. Typically, the residual layer thickness of the final product is determined, and this data is taken into account for post-processing steps.

[0003] It is desirable to control the residual layer thickness and / or residual layer thickness variation of the embossed product.

[0004] The purpose of this invention is to provide a method and / or system for controlling the residual layer thickness of embossed products.

[0005] Therefore, the present invention provides a method for in-situ layer thickness control during imprinting (especially nanoimprinting), comprising the following steps: a) Provide at least one substrate to be imprinted; b) Provide at least one substantially flexible stamp, the at least one substantially flexible stamp including at least one textured area and at least one roller configured to apply pressure to the at least one substantially flexible stamp and / or at least one substrate; c) Applying at least one resin to at least one substantially flexible stamp and / or at least one substrate; d) Imprint at least a portion of the resin with at least one substantially flexible stamp, such that an embossed texture is obtained over the residual layer on the substrate; e) Curing at least part of the resin; and f) Optionally, at least one substantially flexible stamp and at least one substrate can be separated; Wherein, at least after step d), and / or after step e), and / or after step f), the residual layer thickness is determined, and wherein, based on the determined residual layer thickness, at least one imprinting parameter, particularly the imprinting parameter of at least one roller, and more particularly the rotational speed, imprinting pressure, and / or temperature of the at least one roller, is controlled and / or adjusted.

[0006] The method according to the invention provides a solution for controlling the residual layer thickness of an embossed substrate or product. Specifically, the method according to the invention enables the attainment of a desired residual layer thickness and allows the residual layer thickness to remain constant over several embossing cycles. The residual layer thickness of an embossed product can vary due to several factors, such as process factors and / or external factors. To provide a controlled and consistent environment to minimize the impact on the embossing process, (nano)embossing is typically performed in a cleanroom. Imprinting parameters also play an important role in the quality and consistency of the embossing. Important imprinting parameters are the imprinting speed or roller rotation speed, the applied pressure, and the temperature. The texture itself and surface properties such as surface tension affect resin flow. Furthermore, another important factor affecting residual layer thickness is the viscosity of the resin. The viscosity of the resin can also be affected and adjusted by imprinting parameters and / or environmental parameters (such as temperature). The method according to the invention provides an embossing process in which the residual layer thickness is determined and controlled in situ during the process. Determining the (uncured) residual layer thickness after step d) and / or determining the (cured) residual layer thickness after step e) provides useful information about the product being produced. It can detect defects in the (desired) residual layer thickness at an early stage and can initiate adjustments to at least one imprinting parameter to guide the process. In this way, it is possible to limit the production of products or batches that deviate significantly and / or are inconsistent.

[0007] This invention provides an online, direct, non-destructive measurement, monitoring, and / or determination of the residual layer thickness in (nano)imprinting processes, and uses the obtained data to directly adjust at least one imprinting parameter in an advanced feedback loop to closely match the desired residual layer thickness and / or reduce variations in the residual layer thickness. Overall, implementation of this invention will significantly improve the quality and yield of imprinted products (particularly in roll-to-roll nanoimprinting processes). While prior art methods and systems typically utilize offline measurement to control and adjust residual layer thickness, this is inefficient in production because residual layer thickness assessment is performed at different locations and the results need to be processed before adjustments to the imprinting process are suggested and implemented. Therefore, offline measurement will have a strong impact on the throughput of machines or production lines during production. This drawback is overcome by the method and system according to the invention.

[0008] At least a portion of resin is imprinted onto at least one substrate using at least one substantially flexible stamp, which typically results in an imprinted texture over a residual (resin) layer on the substrate. Therefore, the resin layer on the substrate typically consists of a residual (resin) layer and an imprinted texture. After step d) (i.e., after at least a portion of the resin has been imprinted by at least one substantially flexible stamp), the thickness of the residual layer is determined, which essentially means that the resin layer is still uncured. Therefore, the method may include the steps of: determining the uncured residual layer thickness after step d), and based on the determined uncured residual layer thickness, controlling and / or adjusting at least one imprinting parameter (particularly the rotational speed, imprinting pressure, and / or temperature of at least one side of at least one roller). Another imprinting parameter may be the height and / or position of at least one roller. The height and / or position of the roller can be understood as the gap height between the roller and the substrate to be imprinted. In a preferred embodiment, the method includes: determining the residual layer thickness of the residual layer after step d) and before step e), and based on the determined residual layer thickness, controlling and / or adjusting at least one imprinting parameter of at least one roller. In such an embodiment, the residual layer will be substantially uncured. It is also conceivable that, after step e) and before step f), the residual layer thickness is determined, and based on the determined residual layer thickness, at least one imprinting parameter of at least one roller is controlled and / or adjusted. In such an embodiment, at least a portion of the residual layer will be cured. It is also conceivable that the residual layer thickness is determined at several different stages of the imprinting process. The determination of the residual layer thickness is preferably performed at critical areas of the imprinted substrate (e.g., textured areas).

[0009] Preferably, at least one imprinting parameter of at least one roller specifically includes the rotational speed, imprinting pressure, and / or temperature of at least one roller. These imprinting parameters have been found to be related to the characteristics of the residual layer thickness on the imprinted substrate. It is also conceivable that the method includes controlling and / or adjusting multiple imprinting parameters based on the determined residual layer thickness.

[0010] In an advantageous embodiment, if the determined residual layer thickness is greater than a predetermined reference thickness, the rotational speed or imprinting speed of at least one roller is reduced; and / or if the determined residual layer thickness is less than a predetermined reference thickness, the rotational speed or imprinting speed of at least one roller is increased. A higher rotational speed or imprinting speed of one or more rollers will result in an increase in the residual layer thickness. Conversely, a lower rotational speed or imprinting speed of one or more rollers will result in a decrease in the residual layer thickness. For example, the rotational speed of at least one roller can be adjusted using at least one actuator. The change in the rotational speed of at least one roller can be a direct result of adjusting the speed of the motor driving the roller, or an indirect result of the roller following the speed of other adjusted movements (such as the movement of a stamp). Adjusting the rotational speed will have an immediate impact on the produced product; therefore, adjusting the rotational speed is a preferred imprinting parameter upon which the process is based. Generally, it is preferred that the residual layer thickness is equal to the predetermined reference thickness. For example, a deviation of up to 20%, preferably up to 5%, and more preferably up to 1% of the predetermined reference thickness is considered acceptable. Without active control over the imprinting parameters, it is conceivable that the residual layer thickness will vary from batch to batch of imprinted product; and / or, the residual layer thickness of a batch produced in the morning may differ significantly from that of a batch produced in the evening (e.g., by more than 20%). This affects product quality and may cause difficulties in subsequent post-processing of the imprinted product (e.g., during etching).

[0011] Alternatively, it can be envisioned that if the determined residual layer thickness is greater than a predetermined reference thickness, the imprinting pressure applied by at least one roller is increased; and / or if the determined residual layer thickness is less than a predetermined reference thickness, the imprinting pressure applied by at least one roller is decreased. Increasing the imprinting pressure will result in a decrease in the residual layer thickness, while decreasing the imprinting pressure will result in an increase in the residual layer thickness. The pressure applied by at least one or more rollers can have a direct impact on the produced residual layer. The applied pressure is determined based on various parameters, such as: the texture to be imprinted, the materials of the (flexible) stamp and the substrate to be imprinted, the resin composition, the temperature of the rollers, and / or the desired residual layer thickness. Pressure can be a useful imprinting parameter for controlling the imprinting process, particularly for controlling the formation and thickness of the residual layer.

[0012] Another important parameter affecting resin properties is temperature. It is conceivable that the method involves increasing the temperature of at least one roller if the determined residual layer thickness is greater than a predetermined reference thickness; and / or decreasing the temperature of at least one roller if the determined residual layer thickness is less than a predetermined reference thickness. Adjusting the temperature of at least one roller will affect the viscosity of the resin. Higher temperatures will result in lower resin viscosity, which will subsequently result in a thinner residual layer, thus a smaller residual layer thickness. On the other hand, lower temperatures will result in higher resin viscosity, which will result in a thicker residual layer, thus a larger residual layer thickness. Since the temperature of (one or more) rollers generally affects the temperature of the essentially flexible stamp that interacts with at least one roller, it also affects the temperature of the resin being imprinted. Therefore, heating or cooling at least one roller will cause localized temperature variations within the system, which will affect the properties of the resin, and thus also the properties of the residual layer thickness. In this way, temperature control based on the determined residual layer thickness can further improve the imprinting process. Controlling and / or changing the temperature of the deposited resin is also a possible way to guide the residual layer thickness. In this case, the imprinting and cooling times of the resin must be carefully controlled.

[0013] Further advantageously, the amount of resin applied can be controlled and / or adjusted based on the determined residual layer thickness. For example, it is conceivable to increase or decrease the amount of resin applied based on the determined residual layer thickness. If the residual layer thickness is too thin, the amount of resin applied can be increased. It is also conceivable to control the amount of resin applied and / or the location of resin application based on the resin outflow. It is also conceivable that the present invention, particularly the method and / or system, includes resin outflow control. In the context of the present invention, resin outflow is defined as the (final) location to which the resin flows due to the imprinting process. During imprinting, it is desirable to completely imprint a patterned area with resin. To ensure that the patterned area is imprinted, a certain amount of resin is required. Typically, the amount of resin applied is more than a defined minimum amount. In practice, a small excess of resin is usually applied to ensure that the patterned area can be completely imprinted. The amount of excess resin can be based on theoretical and / or experimental data, and is preferably within a predetermined range or limit. While continuously determining the residual layer thickness, the location where the imprinting resin outflow ends can also be detected because abrupt termination and / or optical transitions can be detected. In the embodiment, this optical transition can be observed from reflection at the resin outflow edge due to the abrupt change in refractive index between the area where resin is present and the surrounding area where no resin is present. The transition from resin present between the substrate and the stamp to air present between the substrate and the stamp can be detected by measurement via reflection and / or transmission. For example, the amount of resin outflow can also be determined based on the area and / or volume of outflowing resin, particularly next to the imprint. If the determined area and / or volume of outflowing resin exceeds or falls below a threshold, the amount of resin applied can be adjusted accordingly. If the location where the resin outflow ends deviates from the desired value by more than a certain value, the amount of resin applied can be corrected. In this way, it can be ensured that the area to be imprinted is always covered with resin during imprinting. Similarly, the amount of resin applied can be limited to ensure that the resin outflow does not reach an undesirable location. If the resin outflow deviates from the desired value by more than a certain value, it can also be determined to correct the process settings. As described above, the position of the resin initially applied to the substrate can be adjusted. For example, when the determined resin outflow shape is asymmetrical, the position of at least a portion of the dispensed resin droplets can be moved to obtain the final shape of the desired outflow shape. This may be applicable, for example, when there are non-uniformities in roller flatness, flexible stamp flatness, and / or substrate thickness.

[0014] In a possible embodiment, the residual layer thickness is determined indirectly by determining the amount of resin flowing out. It is conceivable that, given a constant amount of applied resin, a greater resin flow would imply a thinner residual layer thickness. For example, the resin flow can be determined using at least one sensor and / or other optical measurements.

[0015] In yet another embodiment, a resin outflow texture is added adjacent to the effective area. Thus, at least one flexible stamp may include at least one outflow texture adjacent to at least one textured area. In practice, the reflection and / or transmission of the resin outflow texture will vary based on the presence of resin. Therefore, the amount of resin outflow can be determined, and the residual layer thickness can be derived from this. When determining the residual layer thickness based on the amount of resin outflow and / or the resin outflow texture, it is preferable to apply an excess of resin during step c) of the method.

[0016] It is also conceivable that the method according to the invention includes an inspection step in which the texture of the embossed piece is inspected. In cases where the embossed texture is incorrect and / or incomplete, the amount of resin applied can be adjusted, for example, by increasing the amount of resin. Based on the inspection step, it is also conceivable that at least one embossing parameter of at least one roller can be controlled and / or adjusted; for example, the rotational speed, embossing pressure, height, and / or temperature of at least one roller can be controlled and / or adjusted based on at least one inspection step of the embossed texture. Such embodiments can further contribute to providing consistent products that meet high-quality standards. For example, the surface roughness and / or surface profile of the texture can be determined by inspecting the embossed texture using a scanner (e.g., a contact scanner). The method according to the invention may also include a step of controlling the viscosity of at least one resin at application. Therefore, it is conceivable that the applied viscosity can be controlled and / or adjusted based on a determined residual layer thickness. At least one embossing parameter and the viscosity of the applied resin can be controlled simultaneously based on the determined residual layer thickness. Optionally, the method may focus on embodiments in which the viscosity of the applied resin is adjusted only based on the determined residual layer thickness.

[0017] The steps described in the method according to the invention, particularly the subsequent steps, envision continuously determining the residual layer thickness during the imprinting process. The continuously determined residual layer thickness (online and) can form input parameters for the imprinting parameters applied during imprinting. The method may include a control loop in which the continuously determined residual layer thickness values ​​are taken into account for the applied imprinting settings and / or imprinting parameters.

[0018] In a preferred embodiment, the residual layer thickness is determined at at least two distinct locations, particularly at at least two distinct locations within the same residual layer. For example, the residual layer thickness can be determined (or measured) in at least two distinct regions of the residual layer. For example, the residual layer thickness can be determined at multiple locations parallel to the axis of at least one roller. At least one impression parameter can be controlled and / or adjusted based on at least two determined residual layer thickness values, or based on multiple determined residual layer thickness values. For example, it is conceivable that the residual layer thickness is determined after step d) and / or after step e) and / or after step f), and at least one impression parameter is controlled and / or adjusted based on at least two determined residual layer thickness values. It is also conceivable that the residual layer thickness is determined at multiple locations on the impression substrate. For example, it is conceivable that the determined residual layer thickness is the average of multiple determined values. The average value used can be an arithmetic mean or a "non-linear" average. Possibly, the determined residual layer thickness considered for controlling and / or adjusting at least one impression parameter of at least one roller is the average of at least two independently determined residual layer thicknesses based on the same impression substrate and / or the same residual layer. It is conceivable to determine the thickness of the uncured residual layer at multiple locations on the imprinted substrate, and / or to determine the thickness of the cured residual layer at multiple locations on the imprinted substrate. Using multiple measurements or multiple determination steps can further improve the reliability of the determined values, and thus improve the accuracy of the adjustment to at least one imprinting parameter to be performed.

[0019] It is also conceivable that, at least after step d) and / or after step e), the uniformity of the residual layer thickness is determined. Subsequently, based on the determined uniformity or non-uniformity of the residual layer thickness, at least one imprinting parameter of at least one roller can be controlled and / or adjusted. For example, it is conceivable that the residual layer thickness is determined at different locations and / or different steps in the process. In the case where non-uniformity of the residual layer thickness is determined, such as a difference between the first and second sides of the residual layer, at least one imprinting parameter can be adjusted asymmetrically. For example, it is conceivable that the pressure, height, and / or temperature of at least one roller can be adjusted to overcome the non-uniformity of the residual layer thickness. For example, if it is determined that the residual layer thickness on the first side of the residual layer is too thin, while the residual layer thickness on the second side is within the target range, the temperature corresponding to the first portion of the first side of the roller can be reduced and / or the pressure applied at the first side or the corresponding distal end can be reduced.

[0020] Preferably, at least one imprinting parameter of at least one roller can be adjusted asymmetrically. Therefore, the method and system according to the invention preferably include the ability to asymmetrically adjust the imprinting parameters. For example, it is conceivable that at least one roller includes multiple temperature zones, wherein the temperature of at least one zone (preferably each zone) can be individually adjusted and / or controlled. For example, at least one roller may include heating and / or cooling zones located within the roller. It is also conceivable that the system can independently control the pressure at two distal ends of the roller, particularly enabling asymmetrical adjustment of the applied pressure. Preferably, the imprinting speed of at least one roller is kept constant throughout the roller.

[0021] Because imprinting parameters can be dynamically adjusted during the imprinting process, they are typically location-dependent. For example, at the guide edge, the imprinting speed can be slightly lower to compensate for a slightly higher resin content. At the substrate ends, a slightly higher imprinting speed can compensate for any reduction in residual layer thickness that may occur at imprinting locations along the substrate length. For relatively long substrates, a feedback loop may be used to dynamically change at least one imprinting parameter. Dynamic control of imprinting parameters can further improve control over residual layer thickness and its variation.

[0022] The thickness of the residual layer is determined, for example, by using at least one sensor (particularly at least one optical sensor). The at least one optical sensor can be configured to determine the residual layer thickness directly and / or indirectly. For example, the residual layer thickness can be indirectly determined by the resin outflow rate. Various techniques can be applied to determine the residual layer thickness. The residual layer thickness is preferably determined in a non-destructive manner. For example, optical determination of the residual layer thickness is conceivable. For example, the optical determination step can utilize spectroscopic techniques, simultaneously measuring on an additional flat or textured imprinted area within or outside the effective region. It is also conceivable to determine the residual layer thickness using a through-focus scanning optical microscopy (TSOM). Further non-limiting examples of how to determine the residual layer thickness include: using ultrasound, radio wave absorption, Roentgen scanning, mechanical contact scanner (AFM), capacitance and / or frequency resonance, radiometric thickness scanner, surface plasma resonance (SPR), scattering measurements, and / or Mueller matrix polarization measurements.

[0023] Curing of at least a portion of the resin preferably occurs during contact between at least one substantially flexible stamp and the resin. In this way, efficient and effective curing can be achieved, thereby ensuring good quality of the embossed texture. After the resin has at least partially cured, the substantially flexible stamp and the substrate are typically separated. Thus, a substrate with an embossed resin layer is then obtained. At least one substrate used in the method according to the invention is, for example, a glass substrate. However, the substrate can be any type of substrate suitable for embossing. Non-limiting examples are polymer and / or composite substrates. The substrate to be embossed preferably has a substantially smooth upper surface. This can advantageously provide a consistent embossed layer. The substrate can be configured to be substantially flat. The substrate is preferably substantially flat. For example, the substrate may have a substantially flat upper surface intended to be embossed. However, it is also conceivable that the substrate is at least partially curved. The method according to the invention is particularly a roll-to-plate embossing method.

[0024] The present invention also relates to a system for in-situ layer thickness control during imprinting (particularly nanoimprinting), the system preferably configured for applying the method according to the invention, the system comprising: - Optionally, at least one carrier is configured to carry and / or support at least one substrate to be imprinted; - At least one substantially flexible stamp, including at least one textured area and at least one roller configured to apply pressure to at least one substantially flexible stamp and / or at least one substrate; - At least one detection unit for determining the residual layer thickness; and - At least one control unit for controlling and / or adjusting at least one imprinting parameter of at least one roller (particularly the rotational speed, height, imprinting pressure, and / or temperature of at least one roller) based on the determined residual layer thickness.

[0025] The system according to the invention has similar advantages to the method according to the invention, thereby improving the quality and yield of imprinted products. Any of the embodiments described for the method can also be applied to this system. The system according to the invention particularly benefits from the presence of a control unit configured to execute a feedback loop based on the acquired data, and based on this data, to perform direct adjustment of at least one imprinting parameter.

[0026] This system is particularly a roll-to-roll imprinting system. If at least one carrier is used, it is specifically configured to carry and / or support at least one substrate during imprinting. Optionally, the at least one carrier may be formed by at least one (external) support roller. The substantially flexible stamp may also be referred to as a flexible substrate. Typically, the substantially flexible stamp includes at least one textured area. For example, the textured area may include textures typically ranging in size from 500 micrometers to 25 nanometers. The flexible stamp is specifically configured for nanoimprint lithography transfer processes. It is also conceivable to attach at least one flexible stamp to at least one roller, and / or to position at least one flexible stamp above at least one roller. For example, the roller may be at least partially covered by at least one flexible stamp.

[0027] The system is preferably configured such that at least one imprinting parameter of at least one roller can be adjusted asymmetrically. The system may also include at least one actuator for adjusting at least one imprinting parameter of at least one roller (e.g., rotational speed and / or imprinting speed, pressure and / or temperature of at least one roller). It is contemplated that at least one control unit is configured to actuate at least one actuator. In a preferred embodiment, at least one detection unit includes at least one sensor (particularly at least one optical sensor). This detection unit is specifically configured to determine the residual layer thickness in a non-destructive manner. The system may also include at least one applicator for applying resin to at least one substrate and / or at least one flexible stamp. The applicator may further include at least one heating and / or cooling element for controlling the viscosity of the applied resin. Curing of the resin according to the invention can be accomplished, for example, by UV curing. For example, it is contemplated that the applied at least one resin is a crosslinkable resin, particularly crosslinkable during UV curing. The system may optionally also include at least one curing unit, particularly at least one UV curing unit.

[0028] The invention will be further illustrated by the following non-limiting provisions.

[0029] 1. A method for in-situ layer thickness control during imprinting (especially nanoimprinting), comprising the following steps: a) Provide at least one substrate to be imprinted; b) Provide at least one substantially flexible stamp, the at least one substantially flexible stamp including at least one textured area and at least one roller configured to apply pressure to the at least one substantially flexible stamp and / or at least one substrate; c) Applying at least one resin to at least one substantially flexible stamp and / or at least one substrate; d) Imprint at least a portion of the resin with at least one substantially flexible stamp, such that an embossed texture is obtained over the residual layer on the substrate; e) Curing at least part of the resin; and f) Separate at least one substantially flexible stamp from at least one substrate; Wherein, at least after step d) and / or after step e), the residual layer thickness is determined, and wherein, based on the determined residual layer thickness, at least one imprinting parameter of at least one roller is controlled and / or adjusted.

[0030] 2. The method according to Clause 1, wherein, after step d) and before step e), the residual layer thickness is determined, and wherein, based on the determined residual layer thickness, at least one imprinting parameter of at least one roller is controlled and / or adjusted.

[0031] 3. The method according to Clause 1 or Clause 2, wherein, after step e) and before step f), the residual layer thickness is determined, and wherein, based on the determined residual layer thickness, at least one imprinting parameter of at least one roller is controlled and / or adjusted.

[0032] 4. The method according to any of the preceding clauses, wherein at least one imprinting parameter of at least one roller includes the rotational speed, imprinting pressure, height and / or temperature of at least one roller.

[0033] 5. The method according to any of the preceding clauses, wherein if the determined residual layer thickness is greater than a predetermined reference thickness, the rotational speed of at least one roller is reduced; and / or wherein if the determined residual layer thickness is less than a predetermined reference thickness, the rotational speed of at least one roller is increased.

[0034] 6. The method according to any of the preceding clauses, wherein if the determined residual layer thickness is greater than a predetermined reference thickness, the imprinting pressure applied by at least one roller is increased; and / or wherein if the determined residual layer thickness is less than a predetermined reference thickness, the imprinting pressure applied by at least one roller is decreased.

[0035] 7. The method according to any of the preceding clauses, wherein if the determined residual layer thickness is greater than a predetermined reference thickness, the temperature of at least one roller is increased; and / or wherein if the determined residual layer thickness is less than a predetermined reference thickness, the temperature of at least one roller is decreased.

[0036] 8. The method according to any of the preceding clauses, wherein the amount, location and / or viscosity of the applied resin are controlled and / or adjusted based on the determined residual layer thickness.

[0037] 9. The method according to any of the preceding clauses, wherein the residual layer thickness is continuously determined during the imprinting process.

[0038] 10. The method according to any of the preceding clauses, wherein the thickness of the residual layer is determined at at least two different locations of the residual layer.

[0039] 11. The method according to any of the preceding clauses, wherein the residual layer thickness is based on the average of at least two independently determined residual layer thicknesses of the same residual layer.

[0040] 12. The method according to any of the preceding clauses, wherein the curing of at least a portion of the resin is performed during contact between at least one substantially flexible stamp and the resin.

[0041] 13. The method according to any of the preceding clauses, wherein the thickness of the residual layer is determined by using at least one sensor (particularly an optical sensor).

[0042] 14. The method according to any of the preceding clauses, wherein the residual layer thickness is determined by determining the resin outflow amount and / or resin outflow texture.

[0043] 15. The method according to any of the preceding clauses, wherein, at least after step d) and / or after step e), the uniformity of the residual layer thickness is determined; and wherein, based on the determined uniformity or non-uniformity of the residual layer thickness, at least one imprinting parameter of at least one roller is controlled and / or adjusted.

[0044] 16. The method according to any of the preceding clauses, wherein at least one imprinting parameter of at least one roller can be adjusted in an asymmetric manner.

[0045] 17. A system for in-situ layer thickness control during imprinting (particularly nanoimprinting), preferably configured to apply the method according to any one of the preceding clauses, comprising: - Optionally, at least one carrier is configured to support at least one substrate to be imprinted; - At least one substantially flexible stamp, including at least one textured area and at least one roller configured to apply pressure to at least one substantially flexible stamp and / or at least one substrate; - At least one detection unit for determining the residual layer thickness; and - At least one control unit for controlling and / or adjusting at least one imprinting parameter of at least one roller based on the determined residual layer thickness.

[0046] 18. The system according to Clause 17, wherein at least one control unit is configured to control and / or adjust the rotational speed, imprinting pressure, height and / or temperature of at least one roller based on the determined residual layer thickness.

[0047] 19. The system according to Clause 17 or Clause 18, wherein at least one detection unit includes at least one sensor (in particular at least one optical sensor).

[0048] 20. The system according to any one of Clauses 17 to 19, comprising at least one applicator for applying resin to at least one substrate and / or at least one flexible stamp.

[0049] The invention will be further illustrated by the following non-limiting exemplary embodiments, as shown in the accompanying drawings, wherein: Figure 1 A schematic diagram of the system according to the present invention is shown; Figure 2 A block diagram illustrating the present invention is shown; Figure 3a and Figure 3b A portion of the system according to the invention is shown; and Figure 4 A portion of yet another system according to the invention is shown.

[0050] In these figures, similar reference numerals correspond to similar or equivalent elements or features.

[0051] Figure 1A schematic diagram of a system 100 according to the invention is shown. The system 100 shown is a roll-to-plate imprinting system 100. The system 100 is configured for in-situ layer thickness control during imprinting (particularly nanoimprinting). The system 100 is specifically configured for applying the method according to the invention. The system 100 shown includes a carrier 101 configured to carry at least one substrate 150 to be imprinted. It is also contemplated that the carrier is not part of the system 100. The system 100 also includes a substantially flexible stamp 102 including at least one textured region T and a roller 103 configured to apply pressure to the substantially flexible stamp 102 and / or the substrate 150. In the illustrated embodiment, the system 100 includes a plurality of rollers 103, and the substantially flexible stamp 102 is disposed above the rollers 103. The rotation direction of the rollers 103 and the imprinting direction of the imprinting process are indicated by arrows. The system 100 also includes a UV curing unit 107. System 100 further includes: at least one detection unit 104 for determining the residual layer thickness; and an optional control unit 105 for controlling and / or adjusting at least one imprinting parameter of at least one roller 103 (e.g., but not limited to, rotational speed, imprinting pressure, height, and / or temperature of at least one roller 103) based on the determined residual layer thickness. System 100 also includes an applicator 106 for applying resin R to a substrate 150 and / or a substantially flexible stamp 102. Applicator 106 may be a temperature controller. A resin layer is formed on the substrate 150 and subsequently imprinted thereon, such that a texture opposite to the texture T of the substantially flexible stamp 102 is obtained on the resin layer on the substrate. After the imprinting step, the resin layer comprises or substantially consists of a residual (resin) layer and an imprinted texture. The maximum thickness T of the resin layer. R The residual layer thickness (RLT) is greater than that of the residual layer.

[0052] Figure 2A block diagram defining the invention is shown. The diagram illustrates typical steps of the method according to the invention. The diagram shows a practical example of the feedback loop according to the invention. First, initial imprinting settings or imprinting parameters are used, including, for example, values ​​for the rotational speed, pressure, and / or temperature of at least one roller. The method and system are specifically configured to compare the determined residual layer thickness with at least one predetermined reference thickness (possibly including tolerance values). The residual layer thickness (RLT) is continuously determined (preferably at different locations) while the product is being imprinted. The measured RLT values ​​are then returned to the control unit. If they are within defined tolerances, the control unit determines that the desired RLT has been achieved and continues using the initial settings or parameters. Measurements are performed on each imprint, and if there is a deviation from the desired RLT, the system first verifies whether it is thinner or thicker than the desired RLT. If it is thinner than the desired RLT, action A occurs; and if it is thicker than the desired RLT, action B occurs. After action A or B, a new imprint is performed using the new settings or imprinting parameters. As with previous embossed pieces, the RLT is determined again in situ. The control unit receives information on whether the RLT is within tolerance; if yes, the new embossing settings are used again for the next embossed piece. If the answer is no, the obtained RLT is compared with the expected RLT, and the cycle continues. Because the RLT for each product is determined online, any deviation from the expected RLT can be identified at any time, and appropriate modifications can be made. These modifications are actions A and B, such as... Figure 2 As shown. As previously mentioned, three main imprinting parameters can be modified: rotational speed or imprinting speed, imprinting pressure, and temperature. Any one of these parameters or a combination thereof can be changed. First, one parameter should be selected, and when that parameter reaches the machine's limits (considering stability and practical limitations), the next parameter must be changed, and so on. Possible embodiments of actions A and B are listed below, provided by a feedback loop and executed by the control unit and / or actuator for each variable imprinting parameter.

[0053] Rotational speed and / or printing speed of at least one roller: -Action A: Reduce speed; Action B: Increase speed.

[0054] Pressure applied by at least one roller: Action A: Increase pressure; Action B: Reduce pressure.

[0055] Temperature of at least one roller: -Action A: Increase temperature; Action B: Lower the temperature.

[0056] The modification steps performed by at least one control unit and / or actuator in action A or B are preferably as precise as possible to achieve RLT correction with the fewest possible imprints. In this case, a model including resin viscosity, imprint speed, imprint pressure, and temperature can be used. This model can be added to the feedback loop of the control unit, can be material-dependent, and can be theoretical or empirical. If no model exists, percentages of imprint speed, imprint pressure, and / or temperature can be selected as new settings or imprint parameters based on the desired and actually achieved RLT.

[0057] Figure 3a and Figure 3b A portion of the system 200 according to the invention and a schematic diagram of the application of the method according to the invention are shown. The accompanying drawings show the presence of a substrate 250 to be imprinted. Figure 3a The image shows the area 251 to be imprinted. System 200 includes an applicator 206 for applying resin R to a substrate 250 and / or a substantially flexible stamp (not shown). The imprinting direction is indicated by arrows. Figure 3a The illustration shows droplets of resin R disposed on a substrate in a region 251 to be imprinted. Figure 3b This illustrates the case where the substrate 250 is embossed and an embossed texture 252 is obtained. Figure 3b The presence of excess resin R after imprinting is also shown. For successful imprinting, at least the indicated area 251 should be covered by resin R. If resin R is present anywhere outside area 251 after imprinting, this is considered an excess of resin R. To prevent resin overflow, it is conceivable to control the amount of resin applied based on a determined resin outflow rate. For example, it is conceivable to indicate and / or determine the location to which the resin R flows as a result of the imprinting process. Figure 3b Resin boundaries B1, B2, B3, and B4, which can be used to determine the resin outflow amount, are shown. It is also conceivable that at least one minimum boundary Bm1, Bm2, Bm3, and Bm4 be determined, and that if the resin outflow amount does not reach at least one minimum boundary Bm1, Bm2, Bm3, and Bm4, the applied resin amount must be adjusted, particularly by increasing the resin amount. Similarly, a maximum boundary (not shown) can be used to indicate that the resin amount should be reduced. For example, resin boundaries B1, B2, B3, and B4 can be determined by optical analysis. Alternatively and / or additionally, it is also conceivable that the resin outflow amount be determined based on the area and / or volume of outflowing resin outside the imprint texture 252. If the determined outflowing resin area and / or volume exceeds or falls below a threshold, the applied resin amount can be adjusted accordingly. It is also conceivable that the determined resin outflow amount be used to determine the residual layer thickness. With a constant amount of resin applied and no further changes in process conditions, changes in resin boundaries B1, B2, B3, and B4 may indicate a change in the residual layer thickness. Figure 3b The detailed portion of the effluent resin R is further shown. It can be seen that the substrate portion 250 and the resin portion R have different color intensities, so the effluent amount can be determined based on reflection and / or transmission measurements.

[0058] Figure 4 A schematic diagram of a portion of a system 300 according to the invention is shown, configured for applying the method according to the invention. The figure shows the presence of an imprinted substrate 350, indicating the (desired) imprinted area 351. The imprinting direction is indicated by arrows. The figure further shows the presence of excess resin R. The figure further shows that the substrate 350 includes a measurement area 353 for resin detection, particularly for residual layer thickness measurement. For example, it is conceivable that the measurement area 353 has the same texture as the imprinted area 351. In this way, the measurement area 353 can be used to determine the residual layer thickness of all imprinted areas, but the measurement area 353 is located outside the main imprinted area 351, so that the main imprinted area 351 is not negatively affected. It is also conceivable that the measurement area 353 includes a different texture from the main imprinted area 351. For example, the measurement area 353 can be optimized for determining the residual layer thickness.

[0059] It is clear that the present invention is not limited to the exemplary embodiments illustrated and described herein, but numerous variations are possible within the framework of the appended claims, as will be apparent to those skilled in the art. In such cases, it is conceivable to combine, in whole or in part, the different inventive concepts and / or technical measures of the above-described variant embodiments without departing from the inventive concept described in the appended claims.

[0060] The verb “including” and its variations used in this patent document should be understood to mean not only “including”, but also “containing”, “substantially containing”, “formed by” and its variations.

Claims

1. A method for in-situ layer thickness control during roll-to-roll imprinting, particularly nanoimprinting, the method comprising the following steps: a) Provide at least one substrate to be imprinted; b) Provide at least one substantially flexible stamp, the at least one substantially flexible stamp comprising at least one textured area and at least one roller, the at least one roller being configured to apply pressure to the at least one substantially flexible stamp and / or at least one substrate; c) Applying at least one resin to at least one substantially flexible stamp and / or at least one substrate; d) Imprint at least a portion of the resin with at least one substantially flexible stamp, such that an embossed texture is obtained over the residual layer on the substrate; e) Curing at least a portion of the resin; as well as f) Separate at least one substantially flexible stamp from at least one substrate; Wherein, at least after step d) and / or after step e), the residual layer thickness is determined, and wherein, based on the determined residual layer thickness, at least one imprinting parameter of at least one roller is controlled and / or adjusted.

2. The method according to claim 1, wherein, After step d) and before step e), the residual layer thickness is determined, and wherein, based on the determined residual layer thickness, at least one imprinting parameter of at least one roller is controlled and / or adjusted.

3. The method according to claim 1 or 2, wherein, After step e) and before step f), the residual layer thickness is determined, and wherein, based on the determined residual layer thickness, at least one imprinting parameter of at least one roller is controlled and / or adjusted.

4. The method according to any one of the preceding claims, wherein, At least one imprinting parameter of at least one roller includes the rotational speed, imprinting pressure, height and / or temperature of at least one roller.

5. The method according to any one of the preceding claims, wherein, If the determined residual layer thickness is greater than a predetermined reference thickness, the rotational speed of at least one roller is reduced, and / or if the determined residual layer thickness is less than a predetermined reference thickness, the rotational speed of at least one roller is increased.

6. The method according to any one of the preceding claims, wherein, If the determined residual layer thickness is greater than a predetermined reference thickness, the imprinting pressure applied by at least one roller is increased, and / or if the determined residual layer thickness is less than a predetermined reference thickness, the imprinting pressure applied by at least one roller is decreased.

7. The method according to any one of the preceding claims, wherein, If the determined residual layer thickness is greater than a predetermined reference thickness, the temperature of at least one roller is increased, and / or if the determined residual layer thickness is less than a predetermined reference thickness, the temperature of at least one roller is decreased.

8. The method according to any one of the preceding claims, wherein, Based on the determined residual layer thickness, the amount, location, and / or viscosity of the applied resin are controlled and / or adjusted.

9. The method according to any one of the preceding claims, wherein, The residual layer thickness is continuously determined during the imprinting process.

10. The method according to any one of the preceding claims, wherein, The thickness of the residual layer is determined at at least two different locations of the residual layer.

11. The method according to any one of the preceding claims, wherein, The residual layer thickness is the average of at least two independently determined residual layer thicknesses for the same residual layer.

12. The method according to any one of the preceding claims, wherein, Curing of at least a portion of the resin is performed during contact between at least one substantially flexible stamp and the resin.

13. The method according to any one of the preceding claims, wherein, The thickness of the residual layer is determined using at least one sensor, particularly an optical sensor.

14. The method according to any one of the preceding claims, wherein, The thickness of the residual layer is determined by determining the resin outflow rate and / or resin outflow texture.

15. The method according to any one of the preceding claims, wherein, At least after step d) and / or after step e), the uniformity of the residual layer thickness is determined, and wherein, based on the determined uniformity or non-uniformity of the residual layer thickness, at least one imprinting parameter of at least one roller is controlled and / or adjusted.

16. The method according to any one of the preceding claims, wherein, At least one printing parameter of at least one roller can be adjusted in an asymmetric manner.

17. A system for in-situ layer thickness control during roll-to-roll imprinting, particularly nanoimprinting, said system preferably configured to apply the method according to any one of the preceding claims, said system comprising: Optionally, at least one carrier is configured to support at least one substrate to be imprinted; At least one substantially flexible stamp, including at least one textured area and at least one roller, said at least one roller being configured to apply pressure to at least one substantially flexible stamp and / or at least one substrate; At least one detection unit is used to determine the thickness of the residual layer; as well as At least one control unit is used to control and / or adjust at least one imprinting parameter of at least one roller based on the determined residual layer thickness.

18. The system according to claim 17, wherein, At least one control unit is configured to control and / or adjust the rotational speed, imprinting pressure, height, and / or temperature of at least one roller based on the determined residual layer thickness.

19. The system according to claim 17 or 18, wherein, At least one detection unit includes at least one sensor, particularly at least one optical sensor.

20. The system according to any one of claims 17 to 19, comprising at least one applicator for applying resin to at least one substrate and / or at least one flexible stamp.

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