Method for using a hard stamp to produce a soft stamp

Abstract

The invention relates to a method and a device for embossing a soft stamp and also to an embossing device and to a soft stamp. During the embossing with the hard stamp, structures are produced on the soft stamp, and a coating for reducing the adhesive properties is provided on the soft stamp.

Description

[0001] Description

[0002] Method for producing a soft stamp with a hard stamp

[0003] The present invention relates to a method for producing, in particular for embossing, a soft stamp or a soft stamping compound with a master stamp. These master stamps or hard stamps have structures to be molded, which are transferred to the soft stamp during embossing.

[0004] In the state of the art, micro- and / or nanostructures are regularly produced either photolithographically and / or with the help of imprint lithography. Imprint lithography is a process in which micro- and / or nanometer-sized structures are embossed into a material using a stamp. The material is in particular an embossed material applied to a substrate. Such imprint processes have become increasingly important in recent years because they are faster, more effective and more cost-effective than many photolithographic processes. Furthermore, it has been shown that the resolution achievable using imprint lithography is in no way inferior to that which can be achieved with photolithography. In some cases, such as in the so-called "first print", better resolution can be achieved with imprint lithography than with conventional lithography.

[0005] Most versions of the known devices for imprint lithography are built into so-called mask aligners or designed as stand-alone systems, which, however, are usually unable to process substrates larger than 300 mm. Aligners are particularly suitable for special imprint systems, as they have already been widely used in the semiconductor industry for photolithography. This has made it expedient for suppliers to offer extensions and attachments that build on or expand on already known mask aligner technology. The main advantage of mask aligners is that in most cases they already offer optical systems, in particular lamp housings, for the illumination of the substrates and thus the embossed materials, in particular over the entire area.

[0006] In addition to modified or enhanced mask aligners, there are also dedicated imprinting systems that are manufactured for specific applications. These systems are typically alignment systems that can align a stamp to the substrate with high precision. Furthermore, these systems have the ability to generate a vacuum, special dispensing systems, and other modules. Such imprinting systems rarely have the capability to imprint an imprinting material on a substrate larger than 300 mm.

[0007] Imprinting systems exist that enable the production of structures for display devices, i.e. displays, especially curved or flat screens.

[0008] There are five known techniques of imprint lithography:

[0009] • Micro- and / or nanocontact printing (p / nCP)

[0010] • Replica casting (SEM)

[0011] • Micro-transfer molding (pTM) or nanoimprint lithographic (NIL),

[0012] • Microforming in capillaries (MIMIC)

[0013] • solvent-assisted micromolding (SAMIM).

[0014] Imprint stamps are known to be divided into two main categories: hard stamps (made of metal, ceramic materials, voluminous glass, or plastic) and soft stamps (made of polymers, silicones, etc.). All imprint stamps have a textured stamp surface, which typically contains the negative of the desired pattern and is molded into the embossing compound.

[0015] Soft stamps are produced as negatives of a master stamp. Master stamps are stamps used to create the original soft stamp. In other words, master stamps are templates for replication. The master stamp is either a hard stamp made of metal, glass, especially quartz glass, plastic, or ceramic, which is produced once through complex processing, or a soft stamp to be molded, especially a soft stamp with an elastic, stiffened carrier.

[0016] Any number of soft stamps can then be produced from the master stamp. Soft stamps are known to enable conformal, uniform contact over large surfaces.

[0017] Both the master stamp and the soft stamp, as well as the soft stamp and the embossed surface of the substrate, can be separated from each other without damage. A flawless separation of the soft stamp and the master stamp is essential for the production of functioning products. This separability can be the result of a soft stamp's low surface energy, which is achieved through functionalization, particularly coating. Therefore, after stamping with the master stamp and curing of the soft stamp embossing compound, soft stamps are coated with an anti-sticking layer (ASL layer).

[0018] Soft stamps are easier to separate from the substrate than hard stamps. For the automated implementation of soft lithographic processes, it is preferable to support the soft stamp with a carrier. Currently, glass carrier substrates of various thicknesses are widely used. However, the use of thick glass substrates causes the soft stamp to lose at least some of its flexibility. The glass carriers are sufficiently thin glass carriers, which provide the necessary stability for the soft stamp, but are flexible enough to achieve the necessary flexibility. It is also possible to use a polymer film and / or a deformable, thin glass plate, even as a composite material, as a carrier to enable and facilitate the handling of the stamp.A soft punch reinforced with a carrier has increased strength and stiffness that can be adjusted by design, as well as increased dimensional stability compared to non-reinforced soft punches.

[0019] Other designs of soft stamps are manufactured as layered systems made of elastomer or polymer. Mechanical properties such as stability, elasticity, flatness, and roughness can be significantly influenced by the substrate. The structures of the soft stamp are created from the soft stamp material, particularly by molding the master stamp.

[0020] A master stamp or a hard stamp can be produced in particular using a step-and-repeat process (S&R process). This is particularly advantageous when very large master stamps have to be produced. The master stamp is produced using another, master-master stamp. In technical terms, however, the master stamp from which the soft stamps are molded is usually called the sub-master stamp and the master stamp for producing the sub-master stamp is called the master stamp. The definitions can therefore vary. It is disclosed that a master stamp (or sub-master stamp), in particular a large-area one, which is used to mold soft stamps, can be produced using a repeated stamping process (step-and-repeat process). This is characterized by stamping at a first location, then the master stamp-master stamp (or master stamp) moving and then stamping at least one more time.For the precise impression of a master stamp, it is necessary that the soft stamp material has the highest possible adhesion to the master stamp in order to achieve a flawless osculation of the embossing material to the master stamp and thus an accurate impression of the master stamp. At the same time, the soft stamp material has to have low adhesion to the master stamp so that the master stamp can be separated from the originally formed soft stamp. These considerations apply to master stamps that have been molded once, master stamp-master stamps, as well as step-and-repeat master stamps or the stamp itself. Furthermore, it is conceivable that a master stamp is used in a step-and-repeat process to directly emboss the soft stamp. This is particularly advantageous when the soft stamp is very large.The master stamp is moved to a first position, imprints the soft stamp there, then moves to a second position, different from the first position, and imprints again. This process can be repeated until a soft stamp of any size has been created. In particular, the individual imprinted areas of the soft stamp can be imprinted seamlessly.

[0021] Another problem is the detachment of the soft stamp from the surfaces. The soft stamp detachment must be precisely controlled to ensure that the embossed soft stamp structure and the soft stamp are not damaged during demolding from the master stamp.

[0022] When molding a soft stamp, deformations due to material stress can distort the true dimensions of the embossed soft stamp structure, making dimensional accuracy and separability of the embossed soft stamp structures a core task of every stamping process. In particular, a change in the length of the soft stamp without additional compensation changes the material stress, which also means a change in the dimensional accuracy of the stamp. The state of the art for the micro- and / or nanostructuring of surfaces primarily comprises photolithography and various embossing techniques. These embossing techniques use either hard or soft stamps. Recently, embossing lithography techniques have become particularly popular, displacing traditional photolithography techniques. Among embossing lithography techniques, the use of so-called soft stamps is becoming increasingly popular.

[0023] The reason lies in the ease of stamp production, efficient stamping processes, excellent surface properties of the respective stamp materials, low costs, reproducibility of the stamped product, and, above all, the possibility of elastic deformation of the stamp during stamping and demolding. In soft lithography, a stamp made of an elastomer with a micro- or nanostructured surface is used to produce structures ranging from less than 1 μm to greater than 1000 μm in height. It is possible to produce structure widths of several centimeters, especially for Fresnel lenses.

[0024] An important feature for characterizing the finished soft stamp is its roughness, which can reach values ​​(Ra or Rz values) of less than 10 nm, preferably less than 5 nm. Regardless of this, feature sizes can preferably be manufactured starting from 10 nm.

[0025] Besides the advantages of imprint lithography with a soft stamp, there is the disadvantage of this technology, which arises from the elasticity of the stamp, meaning that the dimensional accuracy of the stamp cannot always be guaranteed. This leads to inaccuracies and distortions of the imaged, embossed structures compared to the imprinted structures of the stamp.

[0026] It is therefore the object of the invention to provide an improved method for producing, in particular for embossing, a soft stamp, which at least partially eliminates, in particular completely eliminates, the disadvantages mentioned in the prior art. Furthermore, it is the object of the present invention to provide a method that allows for the efficient and rapid production of suitable soft stamps. Furthermore, it is the object of the present invention to provide a device for carrying out the embossing method, as well as a soft stamp that can be easily separated from a substrate during subsequent use of the embossed soft stamp.

[0027] The present objects are achieved by the features of the independent claims. Advantageous developments of the invention are specified in the dependent claims. The scope of the invention also includes all combinations of at least two features specified in the description, the claims, and / or the drawings. For specified value ranges, values ​​within the specified limits are also considered to be disclosed as limit values ​​and can be claimed in any combination.

[0028] Accordingly, the invention relates to a method for producing, in particular for embossing, a soft stamp with the following steps: i) providing a hard stamp with a first layer, ii) applying a second layer directly onto the first layer, iii) embossing the soft stamp with the hard stamp, wherein the second layer is fixed to the soft stamp, iv) separating the soft stamp from the hard stamp so that the second layer is transferred to the soft stamp.

[0029] In other words, during embossing, i.e. the molding of the structures of the master stamp or the hard stamp onto the soft stamp, a further layer, in particular a functional layer, preferably an ASL layer, is provided on the first layer. In this context, the soft stamp to be embossed can also be formed solely from a soft stamp embossing compound, which is preferably applied directly to the second layer. Surprisingly, it has been found that, particularly with a suitable material combination, an anti-adhesion effect can be generated directly on the soft stamp or the surface to be embossed. Advantageously, the functionalization or adhesion reduction of the surface of the soft stamp can already take place during embossing. This means that a subsequent and additional coating step can be dispensed with, since the soft stamp is already coated with a second layer during embossing.Furthermore, contamination of the soft stamp can be avoided in this way, since the soft stamp can be used directly after embossing and is directly functionalized or surface-treated by the additional layer.

[0030] The steps are preferably carried out in the order described above. During embossing, the structures of the hard stamp are transferred to the soft stamp or molded onto it. Furthermore, the second layer can also have already been applied, so that a hard stamp with the two layers arranged directly on top of each other is provided. During embossing, the soft stamp contacts the second layer. The structures of the hard stamp are molded through the layers onto the soft stamp because the layers are very thin. The first layer preferably covers the surface of the structures of the hard stamp completely or over its entire area. During embossing, the second layer adheres to the now structured surface of the soft stamp. In other words, the second layer is fixed to the soft stamp.The materials are preferably selected such that the adhesion forces between the two layers are at least lower than the adhesion force between the second layer and the soft stamp. In this way, when the hard stamp and the soft stamp are moved apart or separated, the second layer can advantageously be transferred to the soft stamp. In a preferred embodiment of the embossing method, during embossing in step iii), a soft stamp embossing compound of the soft stamp is applied directly to the second layer. In other words, for embossing, the soft stamp embossing compound is applied directly to the second layer, in particular before the structures are transferred by the onset of the effect of embossing forces. Thus, the soft stamp embossing compound is preferably provided directly on the second layer before the embossing step by bringing the soft stamp into contact with the hard stamp.In this way, it is ensured that the second layer can advantageously be provided directly and without contamination on the embossed and thus functionalized soft stamp.

[0031] In a preferred embodiment of the embossing method, the embossing in step iii) further comprises curing the soft stamp. For example, the soft stamp can be held by a carrier, frame, or film that is transmissive for certain wavelengths and can be cured through this by means of radiation. Curing can also be carried out by other known measures. Particularly advantageously, the adhesive forces between the soft stamp and the second layer are also increased during curing, so that a strong bond is created. In this way, separation can be carried out particularly easily and without errors. In this embodiment, it is preferred that the material of the second layer and the material of the soft stamp are compatible during curing, so that the second layer is further fixed to the soft stamp.

[0032] In a preferred embodiment of the embossing method, the first layer is completely wetted by the second layer during application in step ii). In this way, the entire surface of the soft stamp to be structured can advantageously be functionalized or coated during embossing. In a preferred embodiment of the embossing method, the first layer and the second layer are anti-adhesion layers for reducing adhesive forces between interfaces. Both layers are therefore known anti-adhesion layers which functionalize the adhesive properties of the soft stamp in such a way that the soft stamp can be easily and efficiently separated or removed from a product or substrate even when the structures of the soft stamp are later transferred to the product or substrate.In this way, a non-stick coating can advantageously be applied directly during the embossing of the soft stamp. The interfaces between the two layers, as well as between the layers and the hard stamp or the soft stamp, can thus be advantageously adjusted with regard to their adhesive properties. The adhesion between the layers is preferably low, so that the second layer can be easily separated from the first layer, which preferably remains on the hard stamp after separation, and the stamps can be easily separated.

[0033] In an alternative preferred embodiment of the method for producing a soft stamp, in particular for embossing soft stamps, it is provided that i) the first layer is applied to the hard stamp, and ii) the second layer is applied to the hard stamp and iii) the soft stamp embossing compound is applied to a carrier, so that to produce a soft stamp iv) the soft stamp embossing compound is in particular fully contacted with the second layer and v) the soft stamp is subsequently cured. After curing of the soft stamp, vi) the soft stamp is separated from the hard stamp, whereby the separation takes place between the first layer and the second layer. In a preferred embodiment of the embossing method, it is provided that the anti-adhesive layers are at least partially tridecafluoro-

[0034] 1. 1.2.2-tetrahydrooctyltrichlorosilane [CF3 -(CF2)5-(CH2)2-SiC13 ], and / or

[0035] 1. 1,2,2-perfluorodecyltrichlorosilane [CF3-(CF2)7-(CH2)2-SiC13], and / or 1H, 1H,2H,2H-perfluorooctyl trimethoxysilane [CF3-(CF2)5-(CH2)2-SiO(CH3)3, F13-TMS], and / or perfluoropolyether molecules. The layers can also consist of these materials. These materials have proven particularly suitable for use as anti-adhesion layers for soft stamp functionalization or soft stamp embossing.

[0036] In a preferred embodiment of the embossing method, the materials of the first layer and the second layer are different. It has also proven advantageous for the materials to be at least not identical. In this way, the adhesive properties required for transfer, or suitable adhesion forces, can be provided at the corresponding interfaces. Furthermore, the additional second layer to be transferred, preferably an ASL layer, can advantageously be applied to the first layer and affixed directly to the soft stamp during the embossing process. The soft stamp is thus coated simultaneously during the embossing process.

[0037] It has surprisingly been found that the properties of the soft stamping compound can be optimized by means of the first layer and the second layer. In particular, the filling behavior of the soft stamping compound can be advantageously influenced by adjusting the hydrophilic and / or hydrophobic properties. Furthermore, the electrostatic behavior of the finished, cured soft stamp can be influenced by the selection of the second layer in particular. Thus, the conductivity of the soft stamp can be influenced and adjusted via the electrical conductivities of the first layer and the second layer. In further, less preferred embodiments of the method for producing soft stamps and for embossing, it is provided that at least one further layer can be used in addition to the first layer and the second layer, in particular for adjusting the surface properties of the hard stamp and the soft stamp.In some cases, surface properties can be more easily adjusted with multiple thin layers than with two. However, the process is disadvantageous because layer sequences with more than two layers must be built up. This increases manufacturing costs and makes the process more susceptible to errors.

[0038] In a preferred embodiment of the embossing method, it is provided that the first layer and the second layer, in particular along a structured surface of the hard stamp, each have a uniform thickness of less than 5 nm, preferably less than 3 nm, particularly preferably less than 1 nm, most preferably less than 0.3 nm. In other words, the height of the layer along the stamp surface or structured surface is constant. In this way, the embossed structure to be transferred can advantageously be molded. The low thickness or height also ensures that the fine structures can also be reproduced on the soft stamp. Furthermore, a particularly thin layer is surprisingly sufficient to functionalize the soft stamp with regard to the adhesive properties if a second anti-adhesion layer is provided on the first.

[0039] In a further embodiment of the embossing method, it is provided that the first layer and the second layer, in particular along a structured surface of the hard stamp, each have a uniform thickness of less than 30 micrometers, particularly preferably less than 15 micrometers, and most preferably less than 10 micrometers. These layer thicknesses are particularly necessary for large structures when the structure size in a z-direction can be up to 1000:5 to the layer thickness (preferably both values ​​in nm).

[0040] In a preferred embodiment of the embossing method, the first layer and / or the second layer are applied by spin coating, spray coating, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), dip coating, doctor blade coating, or molecular beam epitaxy (MBE). Thus, the second layer can be applied using the aforementioned methods. These methods are particularly suitable for uniformly applying corresponding thin functional layers, while simultaneously allowing the embossed structure to be precisely molded.

[0041] In a preferred embodiment of the embossing method, the soft stamp comprises at least partially polydimethylsiloxane (PDMS), and / or perfluoropolyether (PFPE), polyhedral oligomeric silsesquioxane (POS S), and / or polydimethylsiloxane (PDMS), and / or tetraethylorthosilicate (TEOS), and / or poly(organo)siloxanes (silicone), and / or thermoplastics and / or thermosets. The entire soft stamp or the soft stamping compound to be embossed can also be made of the aforementioned materials.

[0042] In a preferred embodiment of the embossing method, it is provided that, during separation, a first adhesion force between the second layer and the first layer is lower than a second adhesion force between the second layer and the soft stamp. The materials are selected accordingly. Furthermore, the force required for separation can advantageously also be adjusted. Furthermore, for example, the adhesion of the hard stamp and the first layer can be selected such that it remains on the hard stamp during separation. In other words, only the second layer can advantageously be transferred to the soft stamp.

[0043] In a preferred embodiment of the embossing method, the hard stamp is made of at least one of the following materials: glass, metal, metal alloy, ceramic or semiconductor material, preferably silicon, or cured polymer. These materials are ideal for use in the advantageous embossing method as a hard stamp or master stamp.

[0044] In a further preferred embodiment of the embossing method, the hard stamper has a cured polymer as the stamping surface. The hard stamper is preferably reinforced with a rigid support. Thus, the assembled hard stamper consists of a rigid support and a cured polymer impression surface. This embodiment has been found to be particularly advantageous for stamping quality.

[0045] Furthermore, the invention relates to a device for embossing a soft stamp with a hard stamp according to the method according to at least one of the preceding claims, at least comprising a hard stamp with a first layer, coating means for applying a second layer to the first layer, embossing means for embossing the soft stamp with the hard stamp, wherein the second layer can be fixed to the soft stamp, and separating means for separating the soft stamp from the hard stamp, wherein the second layer can be transferred to the soft stamp. In other words, during embossing with the device, a layer, preferably an anti-adhesive layer, can be transferred directly to the soft stamp, since two layers arranged directly above one another are provided on the master stamp or hard stamp.The device is designed to directly enable the embossing of the soft stamp and, at the same time, to perform functionalization with regard to the adhesive properties of the structured soft stamp surface. The device preferably comprises means for applying a soft stamp embossing compound directly to the second layer, in particular before the embossing agents begin to act. The means are designed, in particular, to provide the soft stamp embossing compound to the second layer before embossing. This advantageously allows for precise embossing. Furthermore, contamination between the second layer and the soft stamp embossing compound, and thus between the embossed soft stamp and the second layer affixed to it after embossing, is avoided.

[0046] In a preferred embodiment of the device, the device further comprises curing means for solidifying the soft stamp, wherein the curing means are designed to harden the soft stamp during embossing before the release means take effect. The curing means can be, for example, heat, electromagnetic radiation, in particular UV radiation, etc. The use of radiation, in particular through a carrier / frame of the soft stamp, is preferred for curing. In this way, the second layer can advantageously be hardened and fixed to the soft stamp at the same time. In this way, simple and error-free separation along the interface can be carried out even more easily. The invention is based on the surprising discovery that a master stamp with a layer for functionalization, in particular with low adhesion (so-calledAnti-sticking layer, non-adherent layer, ASL layer, non-stick layer) and a further second functional layer that is different from the first layer, in particular with an ASL layer that is applied to the first layer in order to then mold a soft stamp from the master stamp. When the soft stamp is separated from the master stamp, the interface between the first ASL layer and the second ASL layer serves as the separation surface. When the soft stamp is molded, the first ASL layer remains on the master stamp. When the soft stamping compound hardens, the second ASL layer becomes part of the molded soft stamp and serves as the ASL layer for surface functionalization.

[0047] It is an aspect of the invention to provide a method by means of which an anti-adhesion layer can be transferred directly from the master stamp to the soft stamp during the molding of a soft stamp.

[0048] ASL layers are intended as molecular layers with at least one molecular layer, preferably a molecular layer with a particularly coherent molecular layer, which functionalizes the soft stamp and / or the master stamp.

[0049] The soft stamp adheres to the master stamp for a combination of mechanical and / or physical and / or chemical reasons: mechanical reasons are the enlargement of the surface of the soft stamp due to the structuring, the friction between the master stamp and the soft stamp and a positive connection between the soft stamp embossing compound and the master stamp.

[0050] The physical basis of the adhesive property results primarily from van der Waals forces and / or hydrogen bonds. The chemical basis of the adhesive property results from chemical bonds: ionic and / or covalent, atomic and / or metallic bonds.

[0051] The actual adhesion between the master stamp and the soft stamp is primarily a result of a combination of the three factors mentioned. If the resulting adhesion is strong, there is a risk of inaccurate molding and / or tearing of the soft stamp.

[0052] Those skilled in the art are aware of the use of functional layers, particularly those that reduce adhesion properties, to enable the soft stamp to be molded more optimally from the hard stamp. These non-adherent layers are important for the subsequent use of the structured or embossed soft stamp, since otherwise the soft stamps are molded onto a substrate after the structure has been created and can be difficult to separate from it.

[0053] Contrary to conventional wisdom, at least one additional functional layer, in particular an additional ASL layer, is applied. This additional functional layer remains directly on the molded soft stamp and does not need to be applied in a separate process step.

[0054] The goal is to apply a functional layer to the soft stamp during the production of the soft stamp, so that a functional layer remains on the soft stamp when the soft stamp is removed from the master stamp. From a design perspective, it is advantageous to generally avoid undercuts in the structure.

[0055] In this way, the adhesion properties of the individual soft stamp materials can be coordinated to increase dimensional accuracy and stamping precision while simultaneously reducing the required separation force between the soft stamp and the master stamp. To achieve this, the adhesive properties are generally reduced. At the same time, the ASL coatings reduce friction through chemical and / or physical smoothing of the surfaces, which can be equated with lubrication, even though no traditional wetting lubricants are used.

[0056] The conditions for a dimensionally accurate stamp include the following features and / or properties:

[0057] Dimensional accuracy means that the surface with the 3D surface profile of the master stamp is reproduced flawlessly in the soft stamp and that this shape is retained after demolding.

[0058] In cross-section, the stamps have the following spatial sequence during embossing in a preferred embodiment:

[0059] -Master stamp,

[0060] -First interface: master stamp surface to the first ASL surface,

[0061] -First ASL layer,

[0062] - Second interface: First ASL surface to second ASL surface. When separating the soft stamp from the master stamp, the embossed soft stamp and its ASL layer are separated from this interface.

[0063] - Second ASL layer,

[0064] -Third interface: Second ASL surface to soft stamp surface,

[0065] -Soft stamp,

[0066] -Fourth interface: soft stamp surface to the carrier,

[0067] -Carrier / frame / foil.

[0068] The individual elements of the sequence or stack are described below. The master stamp is preferably made of glass, a metal, a metal alloy, a ceramic, or a semiconductor material such as silicon. The following properties are preferred for the master stamp material: high abrasion resistance, high rigidity, low thermal expansion, high thermal conductivity, low porosity, chemical inertness at operating temperature, and preferably anisotropy characterize the master stamp bulk material. The bulk material is used well below the yield point to ensure the dimensional accuracy of the master stamp, so that the elasticity of the master stamp is in particular two orders of magnitude lower than the elasticity of the cured stamping compound. The elasticity is characterized by the modulus of elasticity, which for the master stamp can preferably have at least two-digit values ​​in gigapascals.Master stamps can also be cured soft stamps made of polymers, elastomers, or silicone. The hard master stamp is preferably produced using electron beam lithography.

[0069] The ASL layers are applied using well-known coating methods from thin-film technology, particularly for liquid layers. These methods are generally known under the umbrella term "coating." This includes spin coating, spray coating, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), dip coating, doctor blade coating, and molecular beam epitaxy (MBE), in which the material is coated either by reaction of volatile precursors or by condensation from the vapor phase onto an existing layer or substrate surface, particularly onto the master stamp surface.

[0070] First interface: The structured master stamp surface to be molded is coated with a layer of the first ASL material to functionalize the master stamp surface. The coating material is used to preferably create a particularly coherent monoatomic and / or monomolecular layer on the master stamp surface. The first ASL material should preferably create a physical and / or chemical bond to the master stamp material. The first interface should preferably not change the geometry of the master stamp surface due to the monomolecular and / or monoatomic first ASL layer. In alternative embodiments of the embossing method, the layer thickness of the first ASL layer is taken into account when producing the master stamp structures so that the correct molding dimensions of the master stamp with the coating of the first ASL layer result in the required structure sizes.

[0071] It is possible that after coating the master stamp with the first ASL material, the first interface connects the first ASL material to the master stamp through a chemical and / or physical reaction, but the functionalizing surface property of the first ASL layer is retained.

[0072] The task of the first ASL layer on the master stamp is to absorb the second ASL layer, which remains on the soft stamp when the soft stamp is demolded from the master stamp.

[0073] The adhesive properties of a surface can be expressed using energy density. The energy density is derived from the force required to separate two surfaces. A person skilled in the art can estimate the surface energy, at least approximately, from the measured force required to separate a stamp from a master, given the size of the separated surface. The energy density can be estimated from the surface energy.

[0074] Depending on the specific design, the mechanical force can occur as a shear force or a normal force. The normal forces can be a point force, a line force, or a surface force. To separate two surfaces, the energy per unit area, referred to in the following text as the energy density, is optimally specified. The energy density is less than 100 mJ / m2, preferably less than 30 mJ / m2, particularly preferably less than 15 mJ / m2, and optimally less than 10 mJ / m2, between the first and second layers, measured after curing at a given temperature (especially above 70°C).

[0075] Preferably, the first ASL layer consists of a single atomic and / or molecular layer that wets the master stamp surface.

[0076] A first ASL material is selected that has very good adhesion properties to the master stamp surface.

[0077] The first ASL material has very good abrasion properties, so that grinding wear is largely prevented or at least minimized.

[0078] The first ASL material is preferably a solid with pronounced polar anisotropic properties for adjusting the adhesion properties of the master stamp. A contact angle measurement can be used to measure the adhesion properties. The contact angle is a measure of the hydrophobicity or hydrophilicity that forms between a test liquid droplet and the surface to be measured. Hydrophilic surfaces flatten the liquid droplet because the adhesive forces between the liquid and the surface dominate over the cohesive forces of the liquid, thus forming low contact angles. Hydrophobic surfaces lead to a more spherical shape of the liquid droplet because the cohesive forces of the liquid dominate over the adhesive forces between the liquid and the surface. Hydrophilic surfaces have a higher surface energy than hydrophobic surfaces.

[0079] For a contact angle measurement of a solid surface such as the master stamp, the first ASL and second ASL surfaces, and the soft stamp surface, water can be used as the test liquid.

[0080] According to the invention, the separation between the master stamp and the soft stamp occurs along the second interface, which is formed by the first ASL and second ASL surfaces. The second interface particularly preferably has the lowest surface energy of all interfaces in the process for embossing or coating the master stamp and separating the soft stamp from the master stamp.

[0081] For this purpose, the material pairing of the first ASL and second ASL materials is selected so that the two materials have the lowest affinity for each other. It has proven surprisingly advantageous to deposit a further, different second ASL layer on the first ASL layer during the layer buildup for molding the soft stamp from the master stamp and then mold the master stamp.

[0082] Preferably, at least the second ASL layer is a monoatomic or monomolecular layer.

[0083] The third interface is formed between the second ASL surface and the soft stamp surface. At this interface, the materials exhibit a high affinity for each other, so that when the master stamp is separated from the soft stamp, the second ASL layer adheres to the soft stamp.

[0084] In particularly preferred embodiments, the third interface disappears at least partially, so that the non-stick property of the second ASL material is integrated into the soft stamp. In other words, an at least partial material integration of the second ASL material into the soft stamp material takes place. Material transport from the soft stamp material into the second ASL material, or vice versa, is suboptimal. The material pairing is carried out in such a way that diffusion is minimized as much as possible. Preferably, at least one permanent bond is formed between the second ASL material and the soft stamp material, particularly during embossing.

[0085] The soft stamp material has at least the following properties: the soft stamp material can be applied to the second ASL material by a coating process. These can be coating processes used in semiconductor technology or coating technology, in particular spray coating, spin-on coating with puddle dispensing or after application in a pattern, doctor blade coating, screen printing, or inkjet printing.

[0086] The soft stamp material can be converted from a monomer state to a polymer in a thermochemical or photochemical reaction, thereby acquiring the necessary properties of strength and dimensional stability.

[0087] The soft stamp material is dimensionally stable and long-term stable, absorbing in the wavelength range of its own crosslinking radiation, yet transparent to the crosslinking radiation from the embossing process, which is used to emboss a product using the soft stamp in subsequent process steps. In preferred soft stamp materials, the soft stamp material and the embossing material can be crosslinked at the same wavelength and / or the same wavelength range. Transparency, measured as transmittance, can be over 70%, preferably over 80%, particularly preferably over 90%, and optimally over 95%, so that a high proportion of the crosslinking radiation penetrates and reacts in the embossing material.

[0088] In order to maintain dimensional stability of the soft stamp material, the soft stamp material must be sufficiently stiff. At the same time, the soft stamp material is elastic so that it can return to the shape obtained during primary forming after demolding from the master stamp and / or a component to be stamped later. Furthermore, the soft stamp material needs the elasticity to absorb the forces of demolding and not tear. In particular, soft stamp materials are used whose elasticity, in particular their non-linear elastic material behavior and their stiffness lead to optimal demolding behavior. The fourth interface is formed between the soft stamp material and the carrier. At this interface, the soft stamp material has a high, preferably extremely high affinity for the carrier material, so that the carrier adheres firmly to the soft stamp.

[0089] Preferably, there is an increased adhesion between the carrier and soft stamp after plasma activation of at least the carrier surface compared to a non-surface-activated compound.

[0090] The carrier material preferably comprises at least one material from the following material classes:

[0091] -Glasses especially

[0092] - Metallic glasses,

[0093] - Non-metallic glasses, especially

[0094] - Organic non-metallic glasses,

[0095] - Inorganic non-metallic glasses, in particular

[0096] - Non-oxide glasses, especially

[0097] - Halide glasses

[0098] - Chalcogenide glasses

[0099] - Oxidic glasses, especially

[0100] - Phosphatic glasses

[0101] - Silicate glasses, especially

[0102] - Aluminosilicate glasses

[0103] - Lead silicate glasses

[0104] - Alkali silicate glasses, especially

[0105] - Alkali-alkaline earth silicate glasses

[0106] - Borosilicate glasses

[0107] - Quartz glass - Borate glasses, especially

[0108] - Alkali borate glasses

[0109] -Materials that are described as glasses but are not, in particular sapphire glass or metal, in particular containing at least one element from the list Cu, Ag, Au, Al, Fe, Ni, Co, Pt, W, Cr, Pb, Ti, Ta, Zn, Sn,

[0110] -technical ceramics,

[0111] -Carbon (graphite, graphene, DLC)

[0112] -Polymers, especially

[0113] -Polyurethanes, Hypalon (material), isoprene rubber (material), nitrile rubber (material), perfluoro rubber (material), polyisobutene (material), thermoplastic elastomers, foams, in particular Arcel (material), Neopor (material), polyisocyanurates, polystyrenes, cellular rubber, acrylic ester-styrene-acrylonitrile, acrylonitrile / methyl methacrylate, acrylonitrile / butadiene / acrylate,

[0114] Acrylonitrile / chlorinated, Polyethylene / Styrene, Acrylonitrile 1-butadiene-styrene, Acrylic polymers, Alkyd resins, Butadiene rubber, Butyl rubber, Casein plastics, Artificial horn, Cellulose acetate, Cellulose ethers and derivatives, Cellulose hydrate, Cellulose nitrate, Chitin, Chitosan, Chloroprene rubber, Cyclo-olefin copolymers, Uniform polyvinyl chloride, Epoxy resin, Ethylene-ethyl acrylate copolymer, Ethylene-polyvinyl acetate, Ethylene-propylene copolymer, Ethylene-propylene-diene rubber, Ethylene vinyl acetate, Expandable polystyrene, Fluororubber, Urea-formaldehyde resin,

[0115] Urea resins, isoprene rubber, lignin, melamine-formaldehyde resin, melamine resins, methyl acrylate / butadiene / styrene, natural rubber, perfluoroalkoxylalkane, phenol-formaldehyde resin, polyacetals, polyacrylonitrile, polyamide, polybutylene succinate,

[0116] Polybutylene terephthalate, polycaprolactone, polycarbonate, polycarbonates, polychlorotrifluoroethylene, polyester, polyester amide, polyether alcohols, polyether block amide, polyetherimide, polyether ketones, polyether sulfone, polyethylene, polyethylene terephthalate, polyhydroxyalkanoates, polyhydroxybutyrate, polyimide, polyisobutylene, polylactide (polylactic acid), polymethacrylmethylimide, Polymethyl methacrylate, polymethylpentene, polyoxymethylene or polyacetal, polyphenylene ether, polyphenylene sulfide, polyphthalamide, polypropylene, polypropylene copolymers, polypyrrole, polystyrene, polysulfone, polytetrafluoroethylene, polytrimethylene terephthalate, polyurethane, polyvinyl acetate, polyvinyl butyral, polyvinyl chloride (rigid PVC), polyvinyl chloride (soft PVC), Polyvinylidene fluoride, polyvinylpyrrolidone, styrene-acrylonitrile copolymer, styrene Butadiene rubber, styrene-butadiene-styrene, synthetic rubber, thermoplastic polyurethane, unsaturated polyester, vinyl acetate copolymers,Vinyl chloride / ethylene / methacrylate, vinyl chloride / ethylene, vinyl chloride-vinyl acetate copolymers, plasticized polyvinyl chloride.

[0117] In another embodiment, the carrier can consist of multiple layers. The carrier serves as a mechanical stabilizer for the soft stamp. The carrier material is transparent to the crosslinking radiation of the soft stamp. In other words, the transmittance is preferably greater than 80%, particularly preferably greater than 90%, most preferably greater than 95%, and optimally greater than 98%, for the given thickness of the carrier material.

[0118] ASL materials can in particular contain at least a portion of tridecafluoro-

[0119] 1. 1.2.2-tetrahydrooctyltrichlorosilane [CF3 -(CF2)5-(CH2)2-SiC13 ], and / or

[0120] 1. 1,2,2-Perfluorodecyltrichlorosilane [CF3-(CF2)7-(CH2)2-SiC13], and / or 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane [CF3-(CF2)5-(CH2)2-SiO(CH3)3, F13-TMS], and / or perfluoropolyether molecules. Soft stamp materials can in particular contain at least a portion of polydimethylsiloxane (PDMS), and / or perfluoropolyether (PFPE), polyhedral oligomeric silsesquioxane (POSS), and / or polydimethylsiloxane (PDMS), and / or tetraethylorthosilicate (TEOS), and / or poly(organo)siloxanes (silicone), and / or thermoplastics and / or thermosets.

[0121] Proceedings

[0122] All prepositions like "on" or "under" do not indicate a direction, but merely a relation. This allows both the coating of the master stamp and the initial forming of the soft stamping compound to be carried out against the direction of gravity. The following text describes the process with the master stamp or hard stamp on the underside and the soft stamp on the top.

[0123] A first embodiment of an exemplary method for embossing comprises the following steps, in particular at least carried out successively and / or simultaneously, in particular with the following sequence:

[0124] In a first process step, the master stamp is coated with a first ASL layer.

[0125] Furthermore, it is possible that at least the first ASL layer has a self-assembly property.

[0126] Furthermore, it is possible that at least the first ASL layer is deposited on the master stamp in a plasma deposition process.

[0127] The first ASL material is applied to the master stamp such that the highly adhesive side of the first ASL layer adheres to the master stamp. The low-adhesive side of the first ASL layer faces away from the master stamp. The first ASL layer wets the master stamp structures as best as possible. After coating with a first ASL layer, the master stamp can be subjected to an optional intermediate step for the modification and / or curing and / or crosslinking of the first ASL layer. Preferably, the first ASL layer can form a chemical bond with the master stamp surface so that, from a macroscopic perspective, the adhesion of the first ASL layer is higher than the adhesion of a Langmuir-Blodgett film. In this case, adapting a surface can be understood as producing a first layer.Accordingly, in particular nitriding, oxidation, coatings such as metallization (nickel plating, chromium plating), surface hardening or carbon enrichment can be understood in the broadest sense as the production of a first layer.

[0128] The resulting surface is the true impression surface of the master stamp.

[0129] In a second process step, the second ASL layer is applied to the first ASL layer. It is important that the first ASL layer has a low affinity to the second ASL layer, allowing for easy and residue-free separation of the molded soft stamp from the master stamp in a subsequent process step.

[0130] The second ASL layer differs at least in part from the first ASL layer.

[0131] Preferably, the layer thicknesses of the first ASL layer and / or the second ASL layer are each less than 5 nm, preferably less than 3 nm, particularly preferably less than 1 nm, ideally less than 0.3 nm.

[0132] In a third process step, the soft stamp is molded onto the master stamp. The second ASL layer remains on the soft stamp.

[0133] In a fourth, optional, process step, the carrier is attached to the back of the soft stamp. For simplicity, the soft stamp and carrier are referred to simply as the soft stamp. The affinity of the second ASL material to the soft stamp material is greater than to the first ASL material, enabling easy separation of the finished soft stamp coated with a second ASL layer from the master stamp with the first ASL layer.

[0134] In a fifth process step, the soft stamp is cross-linked, preferably through the carrier. This process step provides the soft stamp with the necessary dimensional stability and strength. The cross-linking reaction takes place as a photochemical and / or photo-thermochemical, thermochemical, or delayed chemical reaction.

[0135] In this process step, the second ASL layer bonds with the material of the soft stamp, preferably in a non-separable, particularly covalent, bond. This leads to the actual formation of the separation point between the first ASL layer, which forms a non-separable bond, particularly with the master stamp, and the second ASL layer as a component of the soft stamp surface. At the same time, the crosslinking reaction forms a high-affinity bond between the soft stamp material and the carrier.

[0136] In a sixth process step, the hardened soft stamp is separated from the master stamp.

[0137] For example, the soft stamp, coated with a second ASL layer, can be used to emboss structures. The steps described above are part of the embossing process.

[0138] All technical terms used in this disclosure are terms for quantities subject to tolerance, even if these tolerances are not explicitly stated. The manufacturing and / or measurement tolerances typical for engineers apply. For ease of understanding, the quantities are given without tolerance ranges. Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the figures. In the figures, identical components or components with the same function are designated by the same reference numerals. These schematically show:

[0139] Figure 1a is a schematic representation of a first method step of a method for embossing a stamp according to the prior art,

[0140] Figure 1b is a schematic representation of a second process step,

[0141] Figure 1 c is a schematic representation of a third process step,

[0142] Figure 2a is a schematic representation of a first process step of the embossing process according to the invention,

[0143] Figure 2b is a schematic representation of a further process step of the embossing process according to the invention,

[0144] Figure 2c shows a schematic representation of the punches after separation.

[0145] The schematic figures serve to illustrate the process.

[0146] Fig. 1a shows a coated master stamp 91. The coated master stamp 91 consists of a master stamp 94 and an ASL layer 93. The ASL layer 93 is applied to the master stamp surface.

[0147] Fig. 1b shows a master stamp 94 with an ASL layer 93 and an already cured soft stamp 96, which is materially bonded to a carrier 95. After this illustrated process step, the soft stamp 96 and carrier 95 are separated from the master stamp 91. The ASL layer 93 remains on the master stamp 94. The separation occurs between the soft stamp 96 and the ASL layer 93. In other words, the soft stamp 96 is separated from the coated master stamp 91. The separation itself is not shown.

[0148] Fig. 1 c shows the state of the process after the separation of the soft stamp 96 with the carrier 95 from the coated master stamp 91. In the prior art, the soft stamp 96 is coated separately in a further process and can be used for embossing structures on a substrate not shown.

[0149] Fig. 2a shows a master stamp 4 coated with a first ASL layer 3 and a second ASL layer 2. The master stamp 4 with the two coatings of a first ASL layer 3 and a second ASL layer 2 is identified as a multi-coated master stamp 1.

[0150] The first ASL layer 3 has a high adhesive strength to the master stamp 4 and a low-adhesive surface to a second ASL layer 2.

[0151] It is advantageous if the coating of the first ASL layer 3, which is already on the master stamp 4, is carried out with a time delay with the second ASL layer, so that mixing of the first ASL layer 3 and the second ASL layer 2 can be avoided.

[0152] It is important that the second ASL layer 2 completely wets the first ASL layer 3 during processing, but enables a controlled and energetically favorable and dimensionally stable separation, i.e. a very low affinity between the first ASL layer 3 and the second ASL layer 2 is set as a material pairing.

[0153] Fig. 2b shows the result of a further process step for replicating and coating soft stamps.

[0154] The carrier 5 and the soft stamp 6 are bonded to each other with high affinity. The soft stamp 6, in particular, also has a high affinity to the second ASL layer 2. A multi-coated master stamp 1 was used for the primary forming of the soft stamp 6: The layer sequence of the first ASL layer 3, the second ASL layer 2, and the soft stamp 6 were applied to the master stamp 4 in the primary forming process. The first ASL layer 3 has a high affinity to the master stamp 4 but a low affinity to the second ASL layer 2.

[0155] The second ASL layer 2 has a high affinity to the material of the soft stamp 6. The soft stamp 6 also has a high affinity to the carrier 5. The soft stamp 6 is stiffened by the carrier 5.

[0156] It is advantageous to functionalize a soft stamp 6 during the primary forming process with an ASL layer, in particular with the second ASL layer 2.

[0157] Fig. 2c shows the result of the process step for separating the soft stamp 6 from the master stamp 4. The soft stamp 6 was lifted out of the master stamp 4 with the carrier 5. The second ASL layer 2 remains connected to the soft stamp 6. Preferably, the second ASL layer 2 was separated from the first ASL layer 3 of the master stamp 4 without leaving any residue.

[0158] Reference symbol list of multi-coated master stamps

[0159] Second layer, ASL layer

[0160] First shift, ASL shift

[0161] Master stamp, hard stamp

[0162] Carrier, film, frame

[0163] Soft stamp, soft stamp embossing compound, embossing compound single coated master stamp

[0164] ASL layer

[0165] Master stamp, hard stamp

[0166] carrier

[0167] Soft stamp, soft stamping compound

Claims

Patent claims 1. Method for embossing a soft stamp (6) with the following steps: i) providing a hard stamp (4) with a first layer (3), ii) applying a second layer (2) directly onto the first layer (3), iii) embossing the soft stamp (6) with the hard stamp (4), wherein the second layer (2) is fixed to the soft stamp (6), iv) separating the soft stamp (6) from the hard stamp (4) so ​​that the second layer (2) is transferred to the soft stamp (6).

2. Method according to claim 1, wherein during the embossing in step iii) a soft stamping compound (6) of the soft stamp (6) is applied directly to the second layer (2).

3. Method according to one of the preceding claims, wherein the embossing in step iii) further comprises hardening the soft stamp (6).

4. Method according to one of the preceding claims, wherein during the application in step ii) the first layer (3) is completely wetted by the second layer (2).

5. Method according to one of the preceding claims, wherein the first layer (3) and the second layer (2) are anti-adhesion layers (2, 3, 93) for reducing adhesive forces between interfaces.

6. The method according to claim 5, wherein the anti-adhesion layers (2, 3, 93) at least partially comprise tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane [CF3-(CF2)5-(CH2)2-SiC13], and / or 1,1,2,2-perfluorodecyltrichlorosilane [CF3-(CF2)7-(CH2)2-SiC13], and / or 1H,1H,2H,2H-perfluorooctyltrimethoxysilane [CF3-(CF2)5-(CH2)2-SiO(CH3)3, F13-TMS], and / or perfluoropolyether molecules.

7. Method according to one of the preceding claims, wherein the respective materials of the first layer (3) and the second layer (2) are different.

8. Method according to one of the preceding claims, wherein the first Layer (3) and the second layer (2), in particular along a structured surface of the hard stamp (4), each have a uniform thickness of less than 5 nm, preferably less than 3 nm, particularly preferably less than 1 nm, most preferably less than 0.3 nm.

9. Method according to one of the preceding claims, wherein the first layer (3) and / or the second layer (2) are applied by spin coating, spray coating, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), dip coating, doctor blade coating or molecular beam deposition (MBE, molecular beam epitaxy).

10. Method according to one of the preceding claims, wherein the soft stamp (6) at least partially comprises polydimethylsiloxane (PDMS), and / or perfluoropolyether (PFPE), polyhedral oligomeric silsesquioxane (POS S) and / or polydimethylsiloxane (PDMS) and / or tetraethylorthosilicate (TEOS) and / or poly(organo)siloxanes (silicone) and / or thermoplastics and / or thermosets. 1 1. Method according to one of the preceding claims, wherein a first adhesion force between the second layer (2) and the first layer (3) is lower than a second adhesion force between the second layer (2) and the soft stamp (6).

12. Method according to one of the preceding claims, wherein the hard stamp (4) is formed from at least one of the following materials: glass, metal, metal alloy, ceramic or semiconductor material, preferably silicon, cured polymer.

13. Device for embossing a soft stamp (6) with a hard stamp (4) according to the embossing method according to at least one of the preceding claims, at least comprising: - a hard stamp (4) with a first layer (3), - coating agent for applying a second layer (2) to the first layer (3), - embossing means for embossing the soft stamp (6) with the hard stamp (4), wherein the second layer (2) can be fixed on the soft stamp (6), - Separating means for separating the soft stamp (6) from the hard stamp (4), wherein the second layer (2) is transferable to the soft stamp (6).

14. Device according to claim 13, wherein the device further comprises curing means for solidifying the soft stamp (6), wherein the curing means are adapted to cure the soft stamp during embossing before the release means act.

15. Soft stamp (6) produced by the method according to at least one of claims 1 - 12, wherein the soft stamp (6) has the second layer (2).

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