Method and apparatus for fabricating micro- and / or nano-structure

Abstract

To solve a problem in which a soft stamp may deform due to the applied pressure during a nanoimprinting process, and when a structure stamp and / or a substrate are too hard, the need for external pressure, i.e., compression, can lead to pressure-dependent deformations that degrade the quality of the embossing process.SOLUTION: A method includes, in this order, a) clamping a substrate having an embossed mass on a substrate receiving device, b) bringing a structure stamp into contact with the embossed mass, c) at least partially de-clamping the substrate, d) hardening the embossed mass, and f) releasing the embossed mass from the structure stamp.SELECTED DRAWING: Figure 3a

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for fabricating a microstructure and / or a nanostructure.

[0002] In the prior art, microstructures and / or nanostructures are manufactured by photolithographic techniques and / or by using imprint lithography. In recent years, imprint lithography in particular has been proven. Using imprint lithography, it is possible to emboss a microstructure and / or nanostructure-sized structure into a material using a stamp. The material is an embossing mass deposited on a substrate.

[0003] This type of imprint method has been increasing in importance in recent years. This is because the imprint method can be carried out faster, more efficiently and at lower cost than many methods using photolithographic techniques.

[0004] After the deposition of the embossing mass, an alignment adjustment of the structure stamp relative to the substrate is carried out. Thereafter, the structure stamp and the substrate are brought closer to each other. The structure of the structure stamp is molded into the embossing mass. Before the structure stamp is released from the embossing mass, the embossing mass is solidified. The solidification is carried out by heat and / or by electromagnetic radiation.

[0005] In addition to modified or extended mask aligners, there are also specific imprint facilities assembled according to and for specific embodiments. These facilities are generally highly sophisticated alignment adjustment facilities, and the alignment adjustment facilities can align the stamp with respect to the substrate with even higher accuracy. Furthermore, these facilities have the possibility of forming a vacuum and have a special dispensing system and the like.

[0006] The embossing technology works with hard or soft stamps. In the case of embossing lithography technology, the use of so-called soft stamps is particularly preferred. The reasons are the easy production of the stamps, the efficient embossing process, the very good surface properties of each stamp material, the low production costs, the reproducibility of the embossed products, and especially the possibility of elastic deformation of the stamp during embossing and demolding. In soft lithography, stamps made of polymers, especially elastomers, with microstructured or nanostructured surfaces are used, whereby structures in the range from a few nm to less than 1000 μm can be produced.

[0007] Elastomer stamps are produced as negative molds of a master. The master stamp is a hard stamp made of metal, plastic and / or ceramic, and the hard stamp is produced only once by a correspondingly laborious or costly process. From this master, any number of elastomer stamps can then be produced. The elastic modulus of quartz is about 100 GPa. In comparison, the elastic modulus of polymers (hard and soft polymers) is several orders of magnitude smaller at most, and therefore polymers are referred to as "soft" compared to quartz (soft lithography). Elastomer stamps enable conformal and uniform contact via a large surface. Elastomer stamps can be separated from their master stamp and from the embossed product relatively easily. To ensure good separation between the stamp and the substrate, the stamp surface has the lowest possible surface energy. For example, an anti-adhesion coating is often necessary or advantageous.

[0008] To carry out a soft lithography process, it is possible to support an elastomeric stamp by means of a carrier. Currently, for example, glass carrier substrates having various thicknesses are used. By using a thick glass substrate, the elastomeric stamp loses at least partially its flexibility. On the other hand, the flexibility of the stamp can be controlled by the choice of the carrier. The use of a highly rigid carrier generally makes it difficult to separate the stamp from the substrate after the embossing process.

[0009] Similarly, thin substrates according to the prior art require a carrier substrate for better handling. Known soft lithography methods belong, for example, to microcontact printing and / or nanocontact printing (μ / nCP) as well as nanoimprint lithography (NIL).

[0010] In the case of nanoimprint lithography, the curing of the embossing mass can be carried out by heat or by UV radiation. In both cases, the structured stamp is pressed into the embossing mass. In so doing, the structured stamp and the substrate are compressed under pressure so that a high-resolution surface structuring can be carried out. In the case of UV-NIL, work is carried out at a lower crimping pressure compared to thermal NIL, and the process can be carried out at room temperature. The most important parameters in the NIL method are the temperature (especially in the case of thermal NIL), the pressing-in pressure and the interfacial adhesion force between the embossing mass and the structured stamp.

[0011] Soft stamps, and also stamps that are not so soft, especially elastomeric stamps, can be deformed by the pressure applied during the nanoimprint process. This deformation is pressure-dependent. It can be predicted that this deformation will have a stronger influence as the structure becomes smaller and will be more pronounced as the stamp material becomes softer. The deformation or strain caused by crimping of microstructures and nanostructures is reproduced in the cured embossing mass on the embossed substrate, thus degrading the quality and reproducibility of the embossing process.

[0012] If the structural stamp and / or the substrate are too hard, external pressure, in particular pressing, is necessary to achieve conformal or gapless contact between the structural stamp having the stamp structure and the substrate having the embossing mass. In the prior art, actuator devices are used which have a plurality of actuators that can be operated and controlled separately or in a closed loop and which apply a resultant force perpendicular to the substrate receiving surface to the structural stamp and / or the substrate for use in the transfer of the stamp structure.

[0013] In the case of an even larger area, it is difficult to distribute the pressure uniformly over the entire contact surface and to compensate for irregularities. Therefore, non-uniform structuring may occur during embossing.

[0014] Possible non-uniformities on the stamp surface also affect the quality of the embossing process. Furthermore, gas entrapment during pressure embossing and associated embossing defects are known in the prior art.

[0015] Embossing defects that can occur at NIL are, for example, cracks, non-uniformly filled stamp structures (and thus, for example, air entrapment) and non-uniform varnish layer thicknesses.

[0016] Capillary force lithography (CFL), which is not so widespread, also belongs to the soft lithography method and is based on the use of capillary force to fill the stamp structure without external pressure. In "Adv. Funct. Mater. (2002) 12: 405-413", H. H. Lee, the namer, explains CFL in detail. In this case, the elastomer stamp is conformally contacted with the substrate. However, for the filling of the cavity, the embossing mass must have a very low viscosity. CFL is therefore carried out at a relatively high temperature and / or has a high proportion of solvent in the embossing mass and often requires a solvent atmosphere. As the stamp material during CFL, almost only pure PDMS is used. This is because PDMS is permeable to solvents and gases. During embossing with a PDMS stamp, the cavity is filled under the action of capillary force, and the solvent from the embossing mass can diffuse through the PDMS stamp and dissipate. The established embossing mass for CFL is the epoxy material SU-8. Problems such as the swelling of PDMS during solvent-based processes and strong expansion during heat-based processes lead to the fact that CFL is only carried out on a laboratory scale and no industrial conversion by imprint equipment is known. Furthermore, in CFL, the embossing mass is mostly cross-linked by heat.

[0017] U.S. Patent No. 7,442,336 describes, for example, an apparatus and method for embossing a substrate having an embossing mass, where the substrate and the stamp are slowly brought closer until a defined distance is reached, and as a result, the intermediate chamber is filled with the embossing mass by capillary force. At that time, the external force is maintained as slightly as possible according to the properties of the embossing mass, the thickness of the layer to be embossed, and the dimensions of the substrate surface.

[0018] U.S. Patent No. 8,871,048 uses a flexible elastomer stamp, and as a result, the external pressing force can be maintained as low as possible.

[0019] Capillary microforming (MIMIC) also utilizes capillary forces to fabricate structures using a PDMS stamp. In MIMIC, however, a PDMS stamp with a relief structure is pressed against a substrate. This results in a three-dimensionally structured hollow chamber between the stamp and the substrate. A monomer solution is deposited in front of the stamp and then naturally fills the capillary. After curing, the stamp can be removed from the substrate. The three-dimensional polymer structure remains on the substrate.

[0020] In the prior art, a particular problem is that the elastic properties of the soft stamp lead to deformation or distortion of micro- and nanostructures. The deformation and distortion of micro- and nanostructures caused by pressing are reproduced in the cured emboss mass in the embossed substrate, thus degrading the quality and reproducibility of the embossing process.

[0021] The soft stamp can be deformed by the pressure applied during the nanoimprint process. This deformation is particularly pressure-dependent. Furthermore, gas entrapment during pressure embossing and the associated embossing defects are known in the prior art.

[0022] If the structure stamp and / or the substrate are too hard, external pressure, i.e., pressing, is required to achieve conformal and gapless contact between the structure stamp and the substrate with the emboss mass. This can result in pressure-dependent deformation, which degrades the quality of the embossing process.

[0023] Therefore, the object of the present invention is to present an apparatus and method and a substrate that at least partially, and in particular completely, eliminate the drawbacks cited in the prior art.

[0024] The above problem is solved by the features of the independent claims. Advantageous developments of the invention are described in the dependent claims. Any combination consisting of at least two features described in the description, the claims and / or the drawings is also included within the scope of the invention. With regard to the numerical ranges described, any value included within the indicated limits should also be regarded as having been disclosed as a limit value, and patents can be claimed in any combination. Features disclosed for a device should be regarded as applicable to a method as well, insofar as they can be understood as features of a method, and vice versa.

[0025] In this context, hereinafter, structuring and embossing are understood to mean the production of microstructures and / or nanostructures. In particular during embossing, it is desirable that no pressing is carried out.

[0026] The present invention shows a method and a device for producing micro- and / or nanometer-sized structures. The idea underlying the present invention is, inter alia, to solve the technical problems mentioned with regard to production by using extremely thin, particularly flexible substrates and by utilizing capillary forces. In this context, after contact between the embossing mass and the structure stamp, the fixing of the substrate is at least partially, preferably at least by means of one controllable fixing element, released, whereby preferably an embossing process is introduced.

[0027] The present invention therefore particularly deals with a method and a device for conformally contacting a structure stamp and an embossing mass without using external pressure or without pressing the structure stamp and the embossing mass against each other during the embossing process.

[0028] The present invention is therefore a method for producing microstructures and / or nanostructures, comprising at least: a) fixing a substrate having an embossing mass on a substrate receiving device, b) bringing a structure stamp into contact with the embossing mass, c) at least partially releasing the fixing of the substrate, d) Curing the embossing mass, f) Releasing the embossing mass from the structure stamp, Relates to a method having the steps in the above course.

[0029] Furthermore, the present invention is an apparatus for producing a microstructure and / or nanostructure by the aforementioned method, wherein a substrate having an embossing mass can be fixed on a substrate receiving device, a structure stamp can be in contact with the embossing mass, the fixing of the substrate is at least partially releasable, the embossing mass is curable, and the embossing mass is releasable from the structure stamp.

[0030] Furthermore, the present invention relates to an article comprising a microstructure and / or nanostructure, wherein the microstructure and / or nanostructure is produced by the method according to the present invention and / or by the apparatus according to the present invention.

[0031] In a preferred embodiment of the present invention, the substrate is flexible and thus adapted to conform at least partially to the structured stamp, especially after release of the fixation or during structuring of the embossing mass. The substrate especially has a small thickness and / or consists of a material that can be bent partially, so that during production, it can advantageously receive the structure of the structured stamp partially. At that time, the substrate does not have to conform to the structured stamp or may conform completely. After hardening of the embossing mass, the substrate forms a single unit especially with the hardened embossing mass. Thereby, the substrate can advantageously assist the embossing process and avoid embossing errors. Furthermore, the thin and flexible substrate can be deformed during the production process. Especially, the substrate is advantageously drawn conformally to the structured stamp by the action of capillary forces and is deformed in the process. Additionally, the flexibility enables a preferred uniform contact during production. At that time, the flexibility of the substrate advantageously enables a gentle and uniform embossing without embossing errors. When the fixation is released, an additional degree of freedom is advantageously obtained, so that the thin and flexible substrate especially assists the production process as desired by the action of capillary forces. At that time, after release of the fixation, the substrate is free on the substrate receiver device. By attracting the embossing mass and the substrate to the structured stamp, it is also possible for the substrate to be lifted partially or completely from the substrate receiver device, especially by capillary forces. Especially due to the flexibility of the substrate, an external pressure bonding force is not required to transfer the structure to the embossing mass. Thus, the substrate can especially compensate for irregularities, thereby additionally improving the quality of the embossing process.

[0032] In another advantageous embodiment of the invention, after at least partial release of the fixing of the substrate, at least partial detachment of the substrate from the substrate receiving device is effected, in particular, by relative movement between the substrate receiving device and the substrate and / or by relative movement between the substrate receiving device and the stamp receiving device and / or by capillary forces. The detachment can in particular be accompanied by an increase in the distance between the substrate and the substrate receiving device as a result. However, it is also possible that the release of the fixing is not accompanied by detachment of the substrate or an increase in the distance. Furthermore, it is also possible that after at least partial release of the fixing, a distance is formed between the substrate and the substrate receiving device, in particular by means of an actuator. The distance enlarged by the actuator is in this case advantageously adapted to the process, in particular to the material properties. In this case, the substrate remains attached to the embossing mass, in particular by surface tension and capillary forces, or is attracted to the structural stamp, which also advantageously provides degrees of freedom for the substrate. Depending on the arrangement of the substrate receiving device relative to the stamp receiving device, other forces, in particular gravitational forces, may act during the embossing process. In particular, the distance can be enlarged, at least in part, even during contact, in particular by adsorption of the substrate by capillary forces acting on the embossing mass. Preferably, however, the distance is enlarged only after at least partial release of the fixing. The distance can advantageously improve the reproducibility and efficiency of the embossing process, in particular of a plurality of embossing steps carried out simultaneously and / or in parallel. Additionally, due to the degrees of freedom thus obtained, the substrate can be deformed and adapted to the structural stamp. This can in particular avoid embossing errors.

[0033] In another advantageous embodiment of the present invention, the structural stamp is adapted to be a hard stamp or a soft stamp. In particular, the structural stamp can have a soft or hard embossed structure. The hard stamp particularly means a master stamp. By this manufacturing method, soft stamps as well as microstructures and / or nanostructures can be produced efficiently and at low cost, in particular by suitable process parameters and the selection of technically meaningful production materials. Furthermore, by a suitable selection of the structural stamp, deformation of the structural stamp, in particular of the embossed structure thereof, is prevented and uniform and reproducible embossing can be carried out.

[0034] In another advantageous embodiment of the present invention, the embossing mass is structured without pressure and / or without crimping, in particular by capillary forces. Thereby, deformation of the structural stamp can be advantageously reduced, in particular prevented. Furthermore, the reproducibility of the embossing process is improved thereby and embossing errors can be avoided. Additionally, the method becomes more efficient and less costly. The advantageous production of the structure without external crimping force can advantageously improve the material properties of the embossing mass after curing, such as strength values or surface properties. In addition, the substrate can be advantageously retained after peeling. When producing microstructures and / or nanostructures, additionally, the advantage of this method that the smaller the size of the structure, the stronger the capillary force acts is utilized. Accordingly, the embossing can be carried out without mechanical pressure and the embossing mass can be advantageously received by the structure and can thus particularly well conform to the structure. Advantageously, contact or wetting of the structural stamp, in particular of the embossed structure surface, is required when the embossing mass and the structural stamp come into contact.

[0035] In another advantageous embodiment of the present invention, a substrate having an embossing mass is fixed onto a substrate receiving device by at least one controllable fixing element arranged in the substrate receiving device, in particular by vacuum and / or negative pressure, and / or the fixing is released by at least one controllable fixing element, in particular by interruption of negative pressure and / or formation of positive pressure. The at least one fixing element can advantageously fix the substrate, in particular at a predetermined point, onto the substrate receiving device. In this case, the fixing element may in particular be a vacuum track, which is optionally arranged or laid on the surface of the substrate receiving device, in particular in a circular or spiral shape. Preferably, the fixing element can form positive pressure and / or negative pressure. Their resultant force can be applied, in particular optionally, to the substrate, in particular on the side of the substrate facing the substrate receiving device. In particular, for example, curvature of the substrate can also be formed. In this case, the substrate is fixed, for example, by negative pressure at the edge of the substrate receiving device, and positive pressure is formed via another fixing element. At this time, the substrate preferably bulges, particularly at the center. In this way, contact points can be set, particularly during contact. Additionally, the at least one fixing element can advantageously avoid embossing errors, particularly gas entrapment, by technically meaningful, controlled local fixing or release of the fixing. Also, the plurality of fixing elements can release the substrate individually and / or in groups in a predetermined order when releasing the fixing. In this way, preferably, the production of the structure can be started, particularly in a predetermined area. Preferably, the fixing element is formed such that the release of the substrate having a cured embossing mass from the structure stamp can be assisted by the fixing element. The embossing process can advantageously be started by the fixing element. When releasing or liberating the substrate, in particular capillary forces can act advantageously on the embossing mass and / or the substrate. The fixing element enables particularly gentle and uniform production of the structure. In addition, the release of the substrate can also be carried out particularly gently and advantageously. Preferably, the substrate receiving device and the substrate are in the form of a wafer.

[0036] In another advantageous embodiment of the present invention, the fixing of the substrate and at least partial release of the fixing of the substrate are controlled, in particular, by controlling at least one controllable fixing element, and the structuring of the embossing mass and / or the release or peeling of the substrate are carried out at a predetermined time after the contact of the structuring stamp with the embossing mass. The at least one fixing element is preferably operationally controlled by a control unit, and advantageously influences the time point of the release of the fixing of the substrate, and thus influences the peeling or the time point of the release of the substrate. In this case, in particular, the release of the fixing may be introduced by a plurality of controllable fixing elements at various locations. Thus, in particular, the time point and location of the release of the fixing are advantageously controllable. The control unit operationally controls the at least one fixing element, preferably according to a value, in particular a value provided by a sensor.

[0037] In another advantageous embodiment of the present invention, the structuring stamp is formed such that after at least partial release of the fixing, the embossing mass and / or the substrate are conformed or attracted to the structuring stamp without external pressure, in particular by capillary forces. The structuring stamp, in particular the embossing structure of the structuring stamp, is formed such that the structure is advantageously transferred to the embossing mass, in particular by capillary forces. In this case, in particular, the contact surface of the structuring stamp that contacts the embossing mass during contact is formed such that uniform and in particular full contact is possible. Advantageously, the structure or indentation and / or protrusion of the embossing structure of the structuring stamp is arranged such that the structuring can be carried out without pressure. In particular, the embossing structure to be transferred is formed such that the substrate can conform to the structure after release of the fixing. Advantageously, the structuring stamp is also designed such that release is facilitated in an advantageous manner. In particular, the structuring stamp or the embossing structure is reusable. Thus, the manufacturing process can be carried out efficiently and continuously a plurality of times using the same structuring stamp.

[0038] In another advantageous embodiment of the present invention, the substrate is adapted to be held by an embossing mass, in particular by capillary forces and / or surface tension, after contact and / or at least partial release of the fixation. The substrate thereby adheres at least partially to the structure stamp by the embossing mass after release of the fixation. In this case, detachment of the substrate from the substrate receiving device can occur, in particular due to the capillary forces acting on the embossing mass. By releasing the substrate or by releasing the fixation, the substrate is subsequently held, and the substrate can advantageously adapt to the structure stamp. In particular, the substrate can advantageously adapt freely and uniformly to the embossed structure. In addition, irregularities can thus be compensated for. Gas entrainment that may be present in some cases can in particular dissipate. Advantageously, the quality of the embossing process is thus improved.

[0039] In another advantageous embodiment of the present invention, microstructures and / or nanostructures are produced by stacking a plurality of layers and / or adjacent to each other by means of a step-and-repeat method. In this case, the stacking of the multi-layers is carried out in particular at a frequency until the minimum required flexibility of the substrate is no longer provided. Thus, the method can be carried out more efficiently and at lower cost. Furthermore, various layers can be formed in an overlapping manner. Additionally, a plurality of functional structures can be produced adjacent to each other over a large area or in a continuous embossing process. Thus, a wide variety of products, in particular structured films, can be efficiently produced by this method. In particular, it is advantageous in this case that the structure stamp can be used multiple times. This is because there is no crimping pressure, the durability of the structure stamp is improved, or the structure stamp can be used over a plurality of embossing steps.

[0040] In another advantageous embodiment of the present invention, the thickness of the substrate is such that it is from 1 μm to 2000 μm, preferably from 10 μm to 750 μm, more preferably from 100 μm to 500 μm. By using a relatively thin substrate, the flexibility of the substrate can be improved. Thereby, the substrate can better conform to the embossed structure and can compensate for irregularities. Furthermore, a larger number of layers can be formed overlapping each other. This is because the required flexibility is provided over a greater number of embossing steps.

[0041] In another advantageous embodiment of the present invention, the viscosity of the embossing mass is less than 100000 cP, preferably less than 10000 cP, more preferably less than 1000 cP, and most preferably less than 500 cP. By using an embossing mass having a relatively low cP value, in particular the holding of the substrate, the action of capillary forces, and the conformal adaptation to the embossed structure by the substrate and / or the embossing mass can be improved. Furthermore, a low cP value is advantageous for compensating for irregularities. In addition, the flexibility of the substrate is optimally utilized, whereby an improved embossing quality is achieved. Due to the suitable viscosity of the embossing mass, in particular the embossing behavior of the embossing mass and the holding of the substrate can advantageously be adjusted.

[0042] In another advantageous embodiment of the present invention, the structure stamp has an embossed structure and / or is coated with an embossed structure. The embossing stamp, i.e., it may itself have an embossed structure or may be coated with an embossed structure, in particular an embossed structure individually adapted to the embossing process. Thereby, the embossing behavior can advantageously be adjusted. In particular, the production of the structure can be adjusted individually for the process by means of various embossing coatings. Various embossed structures can be transferred, for example, by an embossing stamp, in particular in a step-and-repeat process.

[0043] In another advantageous embodiment of the present invention, an apparatus for producing microstructures and / or nanostructures can, in particular, carry out the method described above, a substrate having an embossing mass can be fixed on a substrate receiving device, a structure stamp can be brought into contact with the embossing mass, the fixing of the substrate is at least partially releasable, the embossing mass is curable, and the embossing mass is designed to be releasable from the structure stamp. In this case, the apparatus can advantageously produce microstructures and / or nanostructures, in particular without additional pressing force. This improves the quality of the embossing process.

[0044] In another advantageous embodiment of the present invention, the apparatus further comprises: one or more sensors for measuring pressure, distance and / or temperature, and / or one or more actuators for adjusting the position of the stamp receiving device and / or the substrate receiving device, and a control unit, the control unit controlling at least one fixing element and / or at least one actuator, in particular as a function of the values measured by at least one sensor, such that the relative movement of the structure stamp with respect to the substrate having the embossing mass, in particular the disappearance or reduction of the distance between the structure stamp and the substrate, can be carried out such that the contact can be carried out without particular pressing. In this case, in particular, the control unit is designed to cause the contact of the structure stamp surface, in particular the embossing structure surface, based on the sensor values, by controlling the operation of the actuator. This advantageously enables the contact to be carried out without additional pressing. In this case, the actuator for widening the distance can be arranged on or act on any member, preferably the substrate receiving device and / or the stamp receiving device. In this way, it can be advantageously ensured that the production of microstructures and / or nanostructures is carried out optimally. Additionally, the control unit is configured such that the fixing of the substrate by the fixing element is advantageously carried out, in particular as a function of the sensor values, during peeling and demolding. This has the advantage that the process quality is improved and embossing errors can be avoided.

[0045] In a less preferred embodiment of the present invention, the control unit of the apparatus is adapted to cause a contact with additional crimping by controlling the operation of separately controllable actuators. The resultant force for the transfer of the stamp structure perpendicular to the substrate receiving surface is less than 500 N. The structure stamp can have a defined area that is, for example, entirely within a wafer format or, alternatively, in particular in a step-and-repeat process, smaller than the substrate to be embossed. The pressure as the resultant force for the transfer of the stamp structure perpendicular to the substrate receiving surface is in particular less than 50 N / mm 2 and preferably less than 25 N / mm 2 and more preferably less than 10 N / mm 2 and most preferably less than 1 N / mm 2 and among these, most preferably less than 0.1 N / mm 2 and less.

[0046] In the present invention, the substrate is extremely thin compared to the substrates described in the prior art. A carrier substrate for stabilizing the substrate (or product substrate) is not used, or the carrier substrate or carrier plate or carrier film is itself thin and flexible. Thereby, the substrate to be embossed is extremely flexible and is particularly flexibly supported.

[0047] The microimprint process and / or the nanoimprint process is carried out by a structure stamp, preferably an elastomer structure stamp, preferably a structure stamp in wafer format. In so doing, the structured stamp is preferably brought into contact with a substrate pre-coated entirely, in particular with an embossing mass provided on the substrate.

[0048] The structural stamp and the substrate are each fixed to the receiving device of the imprinting equipment. The fixing of the substrate to the substrate receiving device is preferably carried out using vacuum or negative pressure. After the alignment adjustment, the contact surfaces of the substrate and the structural stamp are in full contact. Immediately after the structural stamp contacts the substrate, the fixing of the substrate coated with the embossing mass is eliminated, particularly by the interruption of the vacuum. Due to the action of capillary force, the thin and flexible substrate is conformally attracted to the structural stamp. Due to the flexibility of the substrate and the degree of freedom obtained by the detachment of the substrate, the substrate can be deformed and conform to the structural stamp. This enables uniform contact during the embossing process.

[0049] The substrate and the structural stamp are held together by capillary force by the embossing mass located between them. For this purpose, at least the substrate, preferably the substrate and the structural stamp, must have high flexibility. Based on the viscosity of the embossing mass, the intermediate chamber of the structural stamp is also filled completely by the embossing mass by capillary action.

[0050] By utilizing capillary force, additional external pressure or the crimping of the substrate and the structural stamp is unnecessary during embossing or the fabrication of microstructures and / or nanostructures. Thereby, the deformation of the structure of the structural stamp caused by crimping is avoided, particularly prevented.

[0051] Capillary force particularly means the force generated by surface tension and / or interfacial tension. Particularly during fabrication, capillary rise and capillary fall are available. Other forces, such as interfacial adhesion force or the force due to weight, may also occur during fabrication. At that time, due to small microstructures and / or nanostructures, advantageously, the smaller the size of the structure, the greater the action of capillary force or capillary pressure can be utilized.

[0052] The flexibility of the substrate compensates for the irregularities of the structural stamp and / or the substrate and also makes it possible to prevent other embossing defects, such as those caused by air entrainment, so that the quality of the embossing process is extremely high.

[0053] By utilizing capillary forces, additional external pressure or pressing of the substrate and the stamp is not required during embossing. As a result, the device and the embossing process are advantageously simplified because no actuator device for force transmission is required.

[0054] Due to the flexibility of the substrate and the degree of freedom obtained by detachment of the substrate after contact without external pressure, the substrate can be deformed and in particular can conform to the structural stamp.

[0055] Uniform and conformal contact during embossing is possible. As a result, an extremely good imprint is achieved and there are no embossing gaps that may occur due to non-contact or poor-contact zones during embossing and subsequent curing.

[0056] The proposed invention prevents deformation of the micro- and / or nanostructure of the structural stamp caused by pressing.

[0057] The viscosity of the embossing mass is preferably 1 to 100,000 cP, so that a wide selection of embossing materials or embossing varnishes and process optimization by an optimal combination of substrate, stamp material and embossing material are possible.

[0058] The embossing mass does not particularly need to have a low viscosity. In particular, a solvent atmosphere is not required.

[0059] Contact and embossing can be carried out, in particular, at ambient pressure, for example in an air atmosphere or an inert gas atmosphere. Another, in particular controllable process pressure is also possible.

[0060] Contact and embossing can be carried out, in particular, at room temperature and at elevated temperatures.

[0061] The method described advantageously enables a high throughput and, in particular, can reduce the unit cost per production unit.

[0062] It is possible to emboss periodic microstructures and nanostructures as well as aperiodic microstructures and nanostructures.

[0063] Elaborate alignment adjustment is advantageously not necessarily required. The degree of alignment adjustment between the substrate before contact and the structure stamp, for example, whether to perform only a rough alignment adjustment or to finely align with a highly elaborate alignment adjustment facility, can be changed on a case-by-case basis.

[0064] In the method described, various different flexible substrates can be used.

[0065] Embossing or fabrication can be carried out with a smooth surface and / or a rough surface. The roughness can be changed on a case-by-case basis.

[0066] Embossing or fabrication can be carried out, in particular, with a flat stamp surface and / or a curved stamp surface. Due to the flexibility of the substrate and the mobility due to the detachment of the substrate after contact without external pressure, the substrate can be deformed and conform to the stamp.

[0067] UV-curable conductive and non-conductive embossing masses can be used.

[0068] Thermally curable conductive and non-conductive embossing masses can also be used.

[0069] According to the proposed invention, a multilayer embossing process can be carried out. The already embossed and cured first layer on the flexible substrate can be coated again in another step with a second embossing mass, which is then embossed and cured again. The production of further layers is possible, especially as long as sufficient substrate flexibility is still provided. Furthermore, a plurality of embossing steps can be carried out in parallel and / or adjacent to each other and bonded to the previously produced substrate, respectively.

[0070] In the method described, the thickness of the embossing mass on the substrate can be changed as required, so that as a result, thin layers as well as thicker layers consisting of the embossing mass can be embossed or produced.

[0071] According to the proposed invention, it is also possible to manufacture working stamps for imprint lithography in particular, and generally to emboss various different embossing masses curable by heat or electromagnetic radiation, in particular UV radiation, for structuring substrates. Preferably, a UV-curable embossing mass is used.

[0072] The proposed invention can be used in particular for manufacturing the following products: - 1D, 2D and / or 3D diffractive optical elements (DOE), - Microfluidic assemblies, - Lenses and lens systems, - Fresnel lenses, - Biomedical elements, - Polarizers, - Nanostructured electrodes, - IR waveguides, - Angle optical systems for virtual reality applications, - Glass fiber connections, - Working stamps for imprint lithography, - Others.

[0073] Capillary effects are caused, in particular, by the surface tension of the liquid itself and the interfacial tension between the liquid and the solid surface. Capillary forces occur during the interaction between the solid surface and the liquid or, in particular, between solids where there is a small amount of liquid. The cohesive force between liquid molecules and the interfacial adhesion force due to the coating by the embossing mass located between both, between the liquid molecules and the surfaces of the substrate and the structural stamp, contribute to maintaining the contact state between both surfaces after contact, in particular without the influence of external forces. Advantageously, a thin and flexible substrate is used, as a result of which the capillary forces act correspondingly strongly and the substrate is conformally attracted to the structural stamp.

[0074] Another aspect is that as soon as the structural stamp comes into contact with the substrate, the coated thin substrate is released. The fixation of the substrate coated by the embossing mass is released, in particular by the release of the fixation, for example by the interruption of the vacuum.

[0075] Due to the action of the capillary forces, the thin and flexible substrate remains conformally bonded to the structural stamp.

[0076] Due to the flexibility of the substrate and the degree of freedom obtained by the detachment of the substrate from the substrate receiving device, the substrate can be deformed and adapted to the structural stamp. This enables uniform contact during embossing.

[0077] Due to the conformal contact, based on the viscosity of the embossing mass, the intermediate chamber of the structural stamp is also filled completely by capillary action. The capillary pressure depends, in particular, on the size of the structure.

[0078] The smaller the structure, the greater the capillary pressure. High-resolution structuring in the lower nm range (below 50 nm) is possible because the capillary pressure is maximum in this range.

[0079] Furthermore, advantageously, embossing defects that may occur due to the use of external pressing pressure during the embossing process are prevented.

[0080] Method The substrate is extremely thin compared to substrates in the prior art. In this case, a carrier substrate for stabilizing the substrate (or product substrate) is not used, or the carrier substrate or carrier plate or carrier film is itself thin and flexible. As a result, the substrate to be embossed is extremely flexible.

[0081] The microimprint process and / or the nanoimprint process is carried out by means of a structured stamp, preferably a stamp made of elastomer, in particular a wafer-format stamp. In this case, the structured stamp is preferably brought into contact with the substrate pre-coated over the entire surface.

[0082] The structured stamp and the substrate are each fixed, in particular, to the receiving device of the imprint facility. The fixing of the substrate to the substrate receiving device is preferably carried out using vacuum or negative pressure. After the alignment adjustment, the contact surface between the substrate and the structured stamp is brought into contact over the entire surface. As soon as the structured stamp comes into contact with the substrate, the fixing of the substrate coated with the embossing mass is released, in particular by interruption of the vacuum. The detachment process can act over the entire surface or along a predetermined section. Accordingly, the fixing element is controlled.

[0083] When the substrate is completely detached from the receiving device after the contact has been made, the substrate remains attached to the structured stamp due to the capillary effect (capillary force) acting by means of the embossing mass present between the substrate and the structured stamp. An additional external pressing force is not necessary for the success of the embossing or production according to the invention.

[0084] Due to the action of the capillary force, the thin and flexible substrate is conformally drawn towards the stamp. Due to the flexibility of the substrate and the degree of freedom obtained by the detachment of the substrate, the substrate can be deformed and adapted to the stamp. This enables a uniform contact during the embossing process.

[0085] The substrate and the structure stamp are held together by capillary forces by means of an embossing mass located therebetween. For this purpose, at least the substrate must have high flexibility. Based on the viscosity of the embossing mass, the intermediate chamber of the structure stamp is filled by capillary action, in particular completely by the embossing mass.

[0086] The proposed invention thereby prevents deformation of the structure of the structure stamp caused by pressing. Furthermore, the flexibility of the substrate compensates for irregularities of the stamp and / or the substrate and also makes it possible to prevent other embossing defects, for example, embossing defects caused by air entrainment, whereby the quality of the embossing process is extremely high.

[0087] During this adaptation and deformation of the thin substrate in the structure stamp, the gas present between the substrate and the structure stamp, in particular air or an inert gas, can be extruded, so that the embossing can be carried out without gas entrainment. In this case, in particular, it is possible to prevent air or another gas from being entrained by a controlled dissociation by means of a fixing element that holds or fixes the substrate. In this case, in particular, an advantageous dissociation of the substrate can be carried out by individual release of the fixing element, in particular a concentric release along the wafer surface.

[0088] After hardening of the embossing mass, the substrate can be fixed to the receiving device again by means of a vacuum, if necessary, so that demolding can be carried out.

[0089] The method according to the invention for embossing a thin and flexible substrate with a structure stamp for microstructuring and / or nanostructuring is in particular: a) fixing the substrate and the structure stamp to a corresponding receiving device; b) applying an embossing mass onto the substrate; c) coarsely and / or finely adjusting the substrate and the structure stamp; d) Start the embossing process by bringing a substrate having an embossing mass into contact with a structural stamp, in particular by means of a relative movement of a substrate support device and / or a stamp support device, as a result of which the substrate is drawn towards the structural stamp by capillary action, creating a conformal contact, e) Immediately after the contact is made, release the fixing of the flexible substrate to the substrate support device, and due to the thus obtained degree of freedom, the flexible substrate can deform and conform to the structural stamp, f) Cure the embossing mass; g) Fix the embossed substrate to the substrate support device again and release the structural stamp from the substrate, The method is characterized in particular by having the steps in the above-mentioned order.

[0090] Preferably, the embossing starts after contact between the substrate and the structural stamp, after the contact with the embossing mass and thus the manifestation of capillary forces, in particular after the detachment of the substrate.

[0091] The thin substrate, after detachment, is no longer fixed to the support device in particular, and can thus conform to the structural stamp.

[0092] Preferably, the contact represents a full-surface contact. Alternatively, the contact may be made from the edge or from the center. For a punctiform contact, in another embodiment according to the invention, the structural stamp and / or the substrate is curved by means of a bending means. Advantageously, the contact can be assisted in particular by a fixing element which is closed-loop controlled.

[0093] In another embodiment, a step-and-repeat process is carried out. In this case, the structural stamp is used in a step-and-repeat method such that the repeating structure is applied, for example, to the circumferential surface of an embossing roll. In this case, the device is provided with curing means for curing the embossed substrate, in particular for each section, preferably in a section corresponding to one stamp face of the structural stamp and corresponding in particular to the step-and-repeat method.

[0094] Substrate, structure stamp, and embossing mass Particularly preferably, the substrate and / or the structure stamp are flexible to enable conformal contact over the entire substrate surface or the structure stamp surface. In a preferred embodiment, the substrate is extremely thin, and as a result, advantageous flexibility is provided. A carrier substrate for stabilizing the substrate is not used, or the carrier substrate or carrier plate or carrier film is also thin and flexible by itself. Thereby, the substrate to be embossed is extremely flexible. The thin substrate is fixed to the receiving device, and as a result, handling becomes easy.

[0095] The substrate may take any form, preferably circular, rectangular or square, more preferably in a wafer format. The diameter of the substrate is greater than 2 inches, preferably greater than 4 inches, more preferably greater than 6 inches, even more preferably greater than 8 inches, and most preferably greater than 12 inches. The substrate is particularly understood as a wafer.

[0096] The thickness of the substrate is particularly 1 μm to 2000 μm, preferably 10 μm to 750 μm, more preferably 100 μm to 500 μm.

[0097] The structure stamp may take any form, preferably circular, rectangular or square, more preferably in a wafer format. The diameter of the structure stamp preferably generally matches the diameter of the substrate.

[0098] To realize the soft lithography process, an elastomer structure stamp is typically used, preferably a UV-transmissive polymer stamp.

[0099] The transparent elastomeric structure stamp for UV-NIL is made from, for example, the following polymers: silicone, such as polydimethylsiloxane (PDMS), polyorganosilsesquioxane (POSS), perfluoropolyether (PFPE), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), ethylene tetrafluoroethylene, etc. Combinations of multiple materials and multiple layer systems are possible.

[0100] The structure stamp is preferably fixed on a carrier (English: backplane), especially a plate, most preferably a glass carrier. Another possible material for the carrier is polymer and / or metal. The carrier is also especially a stamp carrier substrate.

[0101] The structure stamp has, on its embossing side, especially a plurality of, preferably, embossing structures distributed, especially regularly arranged, over the entire embossing surface on the embossing side. The dimensions of the individual structures of the embossing stamp are preferably in the micrometer range and / or nanometer range. The dimensions of the individual structures are especially less than 20 μm. The dimensions of the individual structures are especially 0.1 nm to 20 μm, preferably 1 nm to 10 μm, more preferably 1 nm to 5 μm, and even more preferably 1 nm to 2 μm.

[0102] The structure stamp can have positive and / or negative patterns on the side facing the substrate surface to be processed. The structure stamp may have a plurality of embossing structures with different dimensions respectively.

[0103] In an alternative embodiment, the structure stamp is made of a hard UV-transmissive material, such as glass, quartz or silicon dioxide. In this embodiment, especially the substrate must have the required thin layer thickness and flexibility. In another embodiment, the structure stamp is made of a hard material, such as silicon, semiconductor material or metal, such as Ni or Ti.

[0104] The embossed mass is hardened in particular by chemical and / or physical processes, in particular the embossed mass is hardened by electromagnetic radiation and / or by temperature.

[0105] Preferably, the curing is carried out by means of electromagnetic radiation, particularly preferably by means of UV radiation, in which case the structure stamp is preferably transparent to the required electromagnetic radiation when it is desired that the embossing mass is cured from the structure stamp side.

[0106] A corresponding radiation source is preferably arranged on the side of the structure stamp facing away from the embossed structures. The structure stamp is therefore transparent in particular in the wavelength range from 5000 nm to 10 nm, preferably from 1000 nm to 100 nm, more preferably from 700 nm to 200 nm, most preferably from 500 nm to 250 nm.

[0107] The optical transparency of the structure stamp is in this case greater than 0.01%, preferably greater than 20%, more preferably greater than 50%, most preferably greater than 80% and most preferably greater than 95%.

[0108] The viscosity of the embossing mass is preferably between 1 and 100,000 cP, which allows a wide selection of embossing materials / embossing varnishes and process optimization by optimal combination of substrate, stamp material and embossing material. The viscosity is in particular less than 100,000 cP, preferably less than 10,000 cP, more preferably less than 1,000 cP and most preferably less than 500 cP.

[0109] The embossing mass is applied to the substrate or the structural stamp, in particular either fully coated or in the form of drops, at defined intervals. Preferably, the embossing mass is applied to the substrate. In this case, the application of the embossing mass can be carried out before or after fixing the substrate. According to the present invention, regions with more embossing mass or more drops can also be defined depending on the topography of the structural stamp or the size of the structure. The application of the embossing mass can be carried out, for example, by a metering device having a nozzle that can be arranged between the structural stamp and the substrate.

[0110] In another embodiment, the present invention can be applied in combination with established industrial coating methods such as, for example, the spin coating method. The coating can be carried out in a separate, dedicated module, apart from the embossing process. Thereby, the coating of the substrate is fast, defect-free, full-surface, particle-free, and standardized. In particular, this results in advantages in throughput and cost reduction.

[0111] Device The present invention relates to a method and an apparatus for transferring and describing a structure, in particular a micro-structure or a nano-structure, from a preferably UV-transparent structural stamp, in particular to the flat side of a substrate that has been fully coated, comprising a substrate holder for receiving the substrate on a substrate receiving surface, and a structural surface of the structural stamp that can be aligned and adjusted parallel to the substrate receiving surface and can be arranged opposite the substrate receiving surface.

[0112] The apparatus can preferably be installed in a process chamber, which can be closed airtight with respect to the surroundings. Thereby, evacuation of the process chamber and / or ventilation of the process chamber with any gas or gas mixture is possible. In this case, the process chamber can be evacuated to a pressure of less than 1 bar, preferably less than 10 mbar, more preferably less than 5 mbar.

[0113] In a preferred configuration, the process according to the invention is carried out at ambient pressure, for example in an air atmosphere or an inert gas atmosphere.

[0114] The process chamber can be purged, in particular, with any arbitrary gas or gas mixture. This is advantageous especially when embossing should not be carried out under vacuum. One possible reason, but not the only reason, for not using a vacuum is the high volatility of the embossing mass when the ambient pressure is low. The high volatility characterized by a high vapor pressure can contribute significantly to the contamination of the process chamber.

[0115] The gas used is preferably one that has as little interaction as possible with the embossing mass. Particularly preferred would be a purge with an inert gas that does not interact with the embossing mass.

[0116] Contact and embossing can be carried out at room temperature or at an elevated temperature. The equipment according to the invention is equipped with corresponding means for temperature control and heating.

[0117] In another embodiment, the contact between the substrate and the structure stamp is particularly critical here because errors can occur, and as a result, a reproducible adjustment accuracy cannot be achieved. The device can be applied, for example, in combination with alignment for precisely adjusted embossing of different layers that overlap, especially using the SVA (SmartView® Alignment) method. At the critical step of contact of the alignment-adjusted contact surface between the substrate and the (nano) structure stamp, an increasingly accurate adjustment accuracy or offset of less than 100 μm, particularly less than 10 μm, preferably less than 1 μm, and most preferably less than 100 nm, most preferably less than 10 nm, is desired.

[0118] In the apparatus to be described, the substrate and the structure stamp are alignment-adjusted and merged. As a result, the approach and adjustment are controlled and carried out for a microimprint embossing process and / or a nanoimprint embossing process. The apparatus preferably comprises a non-contact wedge error compensation system between the stamp and the substrate that are alignment-adjusted in parallel, as described in European Patent No. 2612109, and approach means are used to approach the first surface to the second surface up to the end position in a direction transverse to the receiving surface of the receiving device in the translational direction (T).

[0119] In another embodiment, a rough alignment adjustment is sufficient. An exact alignment adjustment is not particularly necessary. This is because the thin substrate can conform to the structure stamp due to its flexibility and the mobility provided by detachment from the substrate holder.

[0120] The substrate and the structure stamp are fixed to a receiving device (chuck). What is important for the receiving device is, in particular, a flat receiving surface or holding surface for holding and fixing. The receiving device for the substrate and the structure stamp is preferably a vacuum sample holder. It would also be possible to use an electrostatic sample holder, a sample holder that performs fixation using magnetism or electricity, a sample holder that can change the interfacial adhesion characteristics, or a sample holder having a corresponding mechanical clamp.

[0121] In a preferred embodiment, the substrate and the structure stamp are fixed by negative pressure or vacuum on a flat cured surface in which a vacuum track is created by milling. The substrate receiving device has the vacuum track over the entire surface or in the outer zone of the surface. Advantageously, the negative pressure passage extends concentrically, in particular circularly, in particular over the entire circumference, with respect to the center Z of the receiving device. Thereby, advantageously, a particularly uniform fixation is achieved.

[0122] Preferably, the receiving device, in particular the substrate receiving device, has a vacuum track only in the outer zone of the surface, so that the substrate is fixed only partially, in particular at the edges. In particular in this case, it is possible for the substrate and / or the structured stamp to become completely detached from the receiving device. For this purpose, the fixing of the receiving device, in particular the holding vacuum, is stopped. The fixing element, which can apply a negative pressure for fixing, can also apply a positive pressure for detaching the substrate. According to an advantageous embodiment, the receiving device may have a second vacuum zone in order to ensure complete fixing of the substrate after the embossing process and the hardening process.

[0123] If the fixing element is provided as a vacuum element, the fixing element can form a pressure of less than 1 bar, preferably less than 0.1 mbar, more preferably 0.01 mbar, most preferably less than 0.001 mbar, and most preferably less than 0.0001 mbar among others. The fixing elements can be operated and controlled individually or in groups in particular.

[0124] The receiving device according to the invention may alternatively or additionally have sensors, and physical and / or chemical properties can be measured between the fixed substrate and the receiving device using the sensors. These sensors are, for example, temperature sensors, pressure sensors or distance sensors. It is also possible to assemble a plurality of different types of sensors. Furthermore, the sensors may be arranged in another part of the device. For example, the distance sensor or the pressure sensor may be arranged between the receiving devices. In particular, the distance and / or the acting force between the substrate having the embossing mass and the stamp or the stamp structure can be measured.

[0125] Furthermore, if necessary, the contour of the receiving surface may be set back with respect to the receiving plane of the receiving surface, so that a recess is formed that reduces or changes the placement surface. Thereby, substrates (product substrates) that are structured or processed on both sides can also be used.

[0126] In another embodiment, the receiving device is formed such that the substrate and / or the structured stamp can be temperature-controlled either comprehensively or compartment by compartment. The receiving device can be temperature-controlled in a temperature range of -100°C to 500°C, preferably -50°C to 450°C, more preferably -25°C to 400°C, and most preferably 0°C to 350°C.

[0127] One embodiment according to the present invention of the substrate receiving device further enables the handling of a substrate having a liquid layer thereon. The liquid layer is, in particular, a liquid embossing varnish or embossing mass present at the interface during contact.

[0128] The embossing mass is, in particular, coated comprehensively or applied as drops at defined intervals onto the substrate or the structured stamp. Preferably, the embossing mass is applied onto the substrate. Depending on the topography of the substrate and / or the structured stamp, regions with more embossing mass or more drops can also be defined. The application of the embossing mass can be carried out, in particular, by a metering device having a nozzle that can be arranged between the structured stamp and the substrate.

[0129] In another embodiment, the method can be applied in combination with an established industrial coating method, such as the spin coating method. The coating can be carried out in a dedicated module separately from the embossing process. Thereby, the coating of the substrate can be carried out at high speed, defect-free, comprehensively, particle-free, and standardized. This necessarily also brings advantages, especially in terms of throughput.

[0130] In another embodiment, the receiving device preferably has, in particular in the center, a device for deflecting a structured stamp and / or a substrate which is only partially fixed. This deflecting device is referred to as a bending element. The bending element is in particular a nozzle through which a fluid, preferably a gas, can flow out, whereby a positive pressure can be formed, for example, between the structured stamp and the receiving device, and the positive pressure deflects the structured stamp. The deflection of the structured stamp occurs by the structured stamp being preferably fixed by the receiving device via a vacuum at the outer periphery.

[0131] According to the invention, embossing starts, in particular after detachment of the substrate, after contact of the contact surface between the substrate and the structured stamp with an embossing mass, preferably after full contact and thus after the manifestation of capillary forces.

[0132] Further advantages, features and details of the invention are discernible from the following description of the preferred embodiments and on the basis of the drawings. The drawings are schematic.

Brief Description of the Drawings

[0133]

Figure 1a

Figure 1b

Figure 1c

Figure 1d

Figure 1e

Figure 2

Figure 3a

Figure 3b

Figure 4a

Figure 4b

Figure 4c

Figure 4d

[0134] In the figure, the same members or members having the same function are denoted by the same reference numerals. The figure is not shown at the correct scale for the purpose of improving the illustration.

[0135] FIG. 1a shows a cross-sectional view of an apparatus in a first embodiment. FIG. 1a shows in particular the receiving devices 5 and 6 of the apparatus for receiving the structural stamp 2 and the substrate 1. The receiving surfaces of the receiving devices 5 and 6 are adapted in particular to the dimensions and the surrounding contours of the structural stamp 2 and the substrate 1.

[0136] The structural stamp 2 shown in FIGS. 1a to 1e is, in a preferred embodiment, a soft stamp 2 made of an elastomer. The elastomer structural stamp 2 enables conformal and uniform contact via a large surface. To ensure good separation between the structural stamp 2 and the substrate 1, the stamp surface has the lowest possible surface energy.

[0137] If necessary, the elastomer structural stamp 2 is supported by a carrier or a stamp carrier substrate 4. In another embodiment, glass carrier substrates with various thicknesses are used. By using the stamp carrier substrate 4, the elastomer structural stamp 2 loses at least part of its flexibility. On the other hand, the flexibility of the structural stamp 2 can be controlled by the choice of the carrier 4. The carrier 4 may be a plate in an alternative embodiment. In a third embodiment, the carrier 4 is not required. The structure of the structural stamp 2 is not limited to the embodiments shown in FIGS. 1a to 1e.

[0138] The structure 3, 3' of the structural stamp 2 has dimensions in the micrometer range and / or the nanometer range. The fixing of the structural stamp 2 is, in a preferred embodiment, carried out by vacuum or negative pressure via a vacuum track 8 of a vacuum device (not shown). In the embodiments shown in FIGS. 1a to 1e, the negative pressure is applied to the vacuum track 8, which extends concentrically with each other and covers the receiving surface of the stamp receiving device 5 for receiving the structural stamp, to fix the structural stamp. In an alternative embodiment, the vacuum track 8 is only present in the region of the side edge of the receiving surface of the stamp receiving device 5. In this alternative embodiment, only the outer annular section outside the receiving surface of the stamp receiving device 5 is provided for fixing the structural stamp 2 by the vacuum track 8.

[0139] In a preferred embodiment shown in FIGS. 1a to 1e, the substrate 1 is extremely thin compared to substrates in the prior art, and as a result, flexibility is provided. In the first embodiment, a carrier substrate for stabilizing the substrate 1 or the product substrate is not used. The thin substrate 1 is fixed to the receiving device 6, and as a result, handling becomes easy. In an alternative embodiment, a carrier (not shown) for stabilizing the thin substrate 1 is used. The carrier may be, for example, a carrier substrate, a carrier plate, or a carrier film. The carrier supports the substrate and prevents bending, but is also thin itself, and thus has sufficient flexibility. Thereby, the substrate to be embossed is flexible.

[0140] The substrate shown in FIGS. 1a to 1e is, in a preferred embodiment, an extremely thin substrate. The thickness of the substrate 1 is particularly 1 μm to 2000 μm, preferably 10 μm to 750 μm, more preferably 100 μm to 500 μm.

[0141] The thicknesses of the structure stamp 2, the substrate 1, and the embossing mass 7 are not shown in the correct scale in the figure for the purpose of improving the illustration.

[0142] The receiving surface of the substrate receiving device 6 shown in FIG. 1a preferably at least generally conforms to the dimensions of the substrate 1. In a preferred embodiment, the fixing of the substrate 1 is carried out by vacuum or negative pressure via a vacuum track 9 of a vacuum device (not shown).

[0143] In the embodiments shown in FIGS. 1a to 1e, negative pressure is applied to the vacuum track 9 that extends concentrically with each other and covers the receiving surface of the substrate receiving device 6 that receives the substrate 1 in order to fix the substrate 1. The fixing means is formed, in particular, as a plurality of fixing elements that are uniformly distributed on the receiving surface and divided into zones and can be controlled independently. In FIGS. 1a and 1b, first, only the vacuum track 9 provided in the zone of the side edge of the receiving surface of the substrate receiving device 6 is independently controlled and operated (the control or operation is illustrated by arrows). The edge region extends, in particular, up to half of the radius of the receiving surface, preferably up to a quarter of the radius.

[0144] The substrate shown in FIG. 1a is already entirely coated by the embossing mass 7. In a preferred embodiment, the method is applied in combination with an established industrial coating method such as, for example, the spin coating method. The deposition of the layer is carried out, in particular, by the spin method, the spray method or the inkjet method and the dip coating method or the roller coating method. The coating can be carried out in a separate module from the embossing process.

[0145] The application of the embossing mass 7' can be carried out, in an alternative embodiment shown in FIG. 2, by a metering device 13 having a nozzle 12 that can be arranged between the structural stamp 2 and the substrate 1. In this embodiment, the embossing mass 7' is applied onto the substrate 1 as drops at defined intervals. The volume of the drops is accurately measured and controlled, so that the intermediate layer thickness of the possible intermediate layer left between the structural recesses of the embossed structure and the substrate surface is set. Preferably, the intermediate layer thickness is as small as possible. Preferably, the intermediate layer thickness is 50 μm to 0.01 nm, more preferably 10 μm to 0.01 nm, and most preferably 1 μm to 0.01 nm.

[0146] In one embodiment, the substrate receiving device 6 further enables the handling of the substrate 1 having a liquid layer thereon. The liquid layer is, in particular, the liquid embossing varnish or the embossing masses 7, 7' present at the interface during contact.

[0147] Figure 1b shows the device during a further process step. After the alignment adjustment, the contact surfaces of the substrate 1 and the structure stamp 2 are brought close and contacted over the entire surface.

[0148] In an embodiment according to the invention, the approaching relative movement is carried out between the structure stamp 2 and the substrates 1, 1'. Preferably, only one of the receiving devices 5, 6 is moved. Preferably, only the structure stamp 2 is brought close relative to the stationary substrate receiving device 6.

[0149] During the contact step of the structure stamp 2 and the substrate 1 shown in Figure 1b, only the fixing means provided in the edge region of the substrate receiving device 6 are used. As soon as the structure stamp 2 contacts the substrate 1, the fixing of the substrate 1 coated by the embossing masses 7, 7' is released by the interruption of the vacuum. The peeling of the substrate 1 can be controlled and carried out by the decrease in the negative pressure on the receiving surface. Accordingly, the fixing element is controlled. The structure stamp 2 remains fixedly attached to the stamp receiving device 5 unchanged.

[0150] After detachment, the substrate 1 remains attached to the structure stamp 2 due to the capillary effect or capillary force acting by the embossing masses 7, 7' present between the substrate 1 and the structure stamp 2 as shown in Figure 1c, and the embossing process is started over the entire surface. An additional external pressing force is not necessary for the success of the embossing or fabrication according to the invention. The receiving devices 5, 6 are, according to the invention, only brought close to such an extent that the distance H (see Figure 2) decreases to the precisely defined final distance H E and as a result, the imprint process is started without applying an additional external pressing force. The final distance H Eis particularly less than 100 μm, preferably less than 10 μm, most preferably less than 500 nm, and most preferably less than 100 nm among them. Due to the action of capillary force, the thin and flexible substrate 1 is conformally attracted to the structure stamp 2. Due to the flexibility of the substrate 1 and the degree of freedom acquired by the detachment of the substrate 1, the substrate 1 can be deformed and conform to the structure stamp 2. This enables uniform contact during embossing.

[0151] Figure 1c shows an apparatus comprising a particularly UV-transmissive structure stamp 2 loaded into the stamp receiving device 5. At this time, the substrate 1 and the structure stamp 2 are held together by capillary force by the embossing mass 7 located therebetween. For this purpose, at least the substrate 1 must have high flexibility. Based on the viscosity of the embossing mass 7, the intermediate chamber of the structure stamp 2 is also completely filled by the embossing mass 7 by capillary action.

[0152] In the embodiment shown in Figure 1c, after the interruption of the fixation to the substrate receiving device 6 and the action of capillary force, the substrate 1 is no longer placed on the receiving surface of the substrate receiving device 6. In a second embodiment (not shown), the substrate 1 is still placed on the receiving surface of the substrate receiving device 6 without (active) fixation by fixing means and without the influence of external forces. Whether the contact between the substrate 1 and the receiving surface of the substrate receiving device 6 still exists after the detachment of the substrate fixation by the fixing means 9 depends on a plurality of process parameters, such as the amount and viscosity of the embossing masses 7, 7', the size of the structures 3, 3' of the structure stamp 2, the final interval H E and so on.

[0153] In an alternative embodiment (not shown), the structure stamp 2 is present in the lower receiving device and the substrate 1 is present in the upper receiving device. After detachment, the substrate 1 remains attached to the structure stamp 2 due to the capillary force acting by the embossing mass present between the substrate 1 and the structure stamp 2, and also due to additional gravity, and is placed on the embossing mass 7 applied on the structure stamp 2 at a defined interval, for example as a droplet.

[0154] In all illustrated embodiments, external pressure, in particular crimping, is not required to achieve conformal or gapless contact between the structural stamp 2 and the substrate 1 having the embossing mass 7. The device has the advantage that an actuator device need not be used to apply a resultant force orthogonal to the substrate receiving surface to the stamp 2 and / or the substrate 1 for use in transferring the stamp structure 3.

[0155] The method prevents deformation of the structure 3 of the structural stamp 2 caused by crimping. The flexibility of the substrate 1 compensates for irregularities in the structural stamp 2 and / or the substrate 1 and also makes it possible to prevent other embossing defects, for example embossing defects caused by air entrainment, whereby the quality of the embossing process is extremely high.

[0156] In the next process step shown in FIG. 1d, direct crosslinking of the curable embossing mass 7, in particular a photoresist or varnish, is effected by UV light 10. More generally, curing may be effected by electromagnetic radiation, by heat, by an electric current, by a magnetic field or by another method. Preferably, curing is effected through the transparent stamp receiver device 5 and the transparent structural stamp 2. It is also possible to cure the embossing mass 7 via a radiation source provided in or in contact with the stamp receiver device 5.

[0157] In the last process step shown in FIG. 1e, the substrate 1 is separated from the structural stamp 2. The substrate 1 is fixed again to the substrate receiver device 6 prior to separation. The fixing of the substrate 1 is effected by vacuum or negative pressure via a vacuum track 9' of a vacuum device (not shown). For separation, all fixing elements of the substrate receiver device 6, in particular the fixing elements 9' which are independently controllable and uniformly distributed over the receiving surface, are used and actuated (actuation is illustrated by the arrows).

[0158] Figure 1e shows the embossed and cured emboss mass 11 on the substrate 1i after embossing. The method enables high-resolution structuring in the sub-μm range, preferably less than 20 μm, more preferably less than 2 μm, even more preferably less than 200 nm, and most preferably less than 10 nm.

[0159] Preferably, the apparatus comprises a group of modules having one common working chamber that can be closed off from the ambient atmosphere if necessary. In this case, the modules, such as the coating module, imprint module, and unload module, can be arranged in a cluster or star shape around the central module of the transfer device (robot system).

[0160] Figure 3a shows an embodiment with significant substrate deformation due to capillary forces after contact between the substrate 1' and the structure stamp 2, with the emboss mass 7 located therebetween. The relationship between the individual members shown in Figure 3a and the substrate 1' is partially at a different scale, which is due in particular to the significantly enlarged structure 3 of the structure stamp 2. Due to the action of capillary forces, the thin and flexible substrate 1' is conformally drawn towards the structure stamp 2. Due to the flexibility of the substrate 1' and the degree of freedom obtained by the detachment of the substrate 1' from the substrate support device 6, the substrate 1' can deform and conform to the structure stamp 2. This enables uniform contact during embossing. For this purpose, at least the substrates 1, 1' preferably must have high flexibility. The high flexibility of the substrates 1, 1' and the conformal contact reduce or preferably eliminate embossing defects.

[0161] Embossing defects that can occur in the prior art of nanoimprint lithography are, inter alia, cracks, non-uniformly filled stamp structures (and hence air entrapment) and non-uniform varnish layer thicknesses. At that time, the interfacial adhesion force between the embossing mass, for example the varnish, and the structural stamp is critical. This is because, for example, when the cured embossing mass 11' adheres relatively strongly within the recess of the structural stamp 2, distortion or cracks may occur, and as a result, the embossed structure may tear during demolding. A non-uniformly filled stamp structure 3 leads to defects in the individual embossed structures within the cured embossing mass 11'. The filling of the stamp structure depends on a plurality of factors, especially the viscosity of the embossing mass 7, the coating thickness or the size and arrangement and time of the applied embossing mass droplets.

[0162] Another embossing defect stems in particular from defects in the structural stamp 2 itself, for example structures 3 with insufficient depth or non-flat surfaces in some places. Defects, such as non-flat surfaces of the structural stamp 2, are compensated for by the flexibility of the substrate 1.

[0163] Since no external pressure is applied to the soft structural stamp 2, it cannot be deformed during the process according to the invention. Since the substrates 1, 1' are also thin, stamp defects or defects that would otherwise occur in the prior art can be compensated for or not occur at all. Figure 3b shows the embossed and cured embossing mass 11' on the substrate 1i after demolding.

[0164] The proposed invention can be used in particular for manufacturing the following products: - 1D, 2D and / or 3D diffractive optical elements (DOEs), - Microfluidic component groups, - Lenses and lens systems, - Fresnel lenses, - Biomedical elements, - Polarizers, - Nanostructured electrodes, - IR waveguides, - Angle optical system for virtual reality applications, - Glass fiber connection part, - Working stamp for imprint lithography, - Others.

[0165] Figures 4a to 4d show another embodiment of the step and repeat method. In this case, a structure stamp 2' smaller than the substrate 1'' on which the structure is to be embossed is used. The process is repeated at appropriate frequencies or arbitrarily as shown in Figures 4a to 4d to emboss the entire substrate 1'' having an embossing mass 7''. The equipment according to the present invention can preferably be installed in a process chamber, and the process chamber can be hermetically closed with respect to the surroundings. Thereby, evacuation of the process chamber and / or ventilation of the process chamber with any gas or gas mixture becomes possible.

[0166] Figure 4a shows a substrate 1'' having a complete layer of the embossing mass 7''. In another embodiment, the drops of the embossing mass can be applied on the substrate 1'' at defined intervals. The structure stamp 2' of the step and repeat method is smaller than the substrate 1'' in this case. Figure 4a also shows a cross-sectional view of the receiving device 5' of the device for receiving the structure stamp 2' in particular. The structure 3' of the structure stamp 2' has dimensions in the micrometer range and / or nanometer range. Fixing of the structure stamp 2' to the stamp receiving device 5' is preferably carried out by vacuum or negative pressure via a vacuum track of a vacuum device (not shown) in a preferred embodiment.

[0167] In an advantageous embodiment of the present invention, the device is adapted to have curing means for curing the embossed substrate 1'', particularly for each compartment, preferably in a compartment corresponding to one stamp face of the structure stamp, particularly corresponding to the step and repeat method.

[0168] The step-and-repeat apparatus should be regarded as a development of the apparatus described in European Patent Application Publication No. 2287666. European Patent Application Publication No. 2287666 describes a step-and-repeat apparatus for embossing a substrate in a plurality of embossing steps in an embossing process, and further apparatuses included in this apparatus, in particular a regulating apparatus.

[0169] In the process step shown in Figure 4b, the embossing mass 7’’ is structured by the step-and-repeat structural stamp 2’. The structural stamp 2’ is then run to the first position, whereby embossing can be carried out in this first position. Preferably, only the structural stamp 2’ is approached relative to the stationary carrier substrate. After contact, direct crosslinking of the curable embossing mass 7’’, in particular a photoresist or varnish, is carried out by UV light 10. More generally, curing may be carried out by electromagnetic radiation, by heat, by an electric current, by a magnetic field or by another method. Preferably, curing is carried out through the transparent stamp receiver 5’ and the transparent structural stamp 2’. According to the invention, it is also possible to cure the embossing mass 7’’ via a radiation source provided in or in contact with the stamp receiver 5’.

[0170] After the release shown in Figure 4c, a defined section of the substrate 1’’ is embossed and has the cured embossing mass 11’.

[0171] In a further process step of the step-and-repeat method shown in FIG. 4d, the structural stamp 2' of the step-and-repeat system travels from a first position to a predetermined second position different from the first position and is embossed again. After contact, direct crosslinking of the embossed curable embossing mass 7'' is again effected by UV light 10. According to the invention, multiple curing is also possible, in which case a first curing is effected locally for each individual embossing step, and after completion of the step-and-repeat method, further curing of the entire substrate 1'' is effected, for example, within a specific module.

[0172] The process shown in FIGS. 4a to 4d can be repeated several times until the desired surface of the substrate 1'' has been embossed. The structural stamp 2' in this embodiment enables embossing without the influence of external forces after contact with the embossing mass 7'' provided on the substrate 1''. The structural stamp has means for moving it, in particular means for moving it parallel to the substrate surface, and a lifting system (not shown) for approaching it along the Z direction and for releasing. The high precision of the running table of the step-and-repeat system enables seamless embossing by the structural stamp 2' over the entire extent of the substrate 1''. Alignment adjustment with respect to a previously embossed structure, in particular with respect to an overlap structure at the edge of a previously embossed structural section, for example, is possible according to the invention. The use of an endless substrate in the step-and-repeat method is also possible. In this case, the endless substrate is, in particular, a substrate stored on a first roll, the length of which is many times greater than its width. In particular, the endless substrate is a film.

[0173] By repeated and adjacent embossing by the structural stamp 2', for example, a lens array, in particular a microlens array and / or a nanolens array, is produced.

[0174] No additional external pressure is necessary for successful embossing according to the invention. The stamp receiving device 5' according to the invention ensures that the spacing H is precisely aligned to the precisely defined final spacing H' at a predetermined position. E to the substrate 1'', so that the imprint process can be started without applying any additional external compression force. E is in particular less than 100 μm, preferably less than 10 μm, most preferably less than 500 nm, most preferably less than 100 nm. Due to the action of capillary forces, the thin and flexible substrate 1″ is conformally attracted to the structure stamp 2′. The flexibility of the substrate 1″ allows it to deform and adapt to the structure stamp 2′. This allows a uniform contact during embossing. [Explanation of symbols]

[0175] 1,1',1'' board, product board 1i Board after embossing 2,2' Structural stamp 3,3' embossed structure 4 Stamp carrier substrate or backplate for stabilization 5,5' Stamp receiving device 6. Board receiving device 7,7',7'' embossed mass 8,8' Vacuum track installed in stamp receiving device 9,9' Vacuum track provided in substrate receiving device 10 Radiation source 11,11' Embossed and hardened embossed mass 12 Nozzles 13 Metering device H interval H E ,H' E Last Interval

Claims

1. A method for producing microstructures and / or nanostructures, comprising at least: a) fixing a substrate (1, 1', 1'') having an embossed mass (7, 7', 7'') on a substrate receiving device (6); b) bringing a structure stamp (2, 2') into contact with said embossing mass (7, 7', 7''); c) at least partially releasing said clamping of said substrates (1, 1', 1''); d) hardening the embossed mass (7, 7', 7''); f) releasing the embossed mass (7, 7', 7'') from the structure stamp (2, 2'); A method having the steps as described above.

2. The method according to claim 1 , wherein said substrate (1, 1', 1'') is flexible and thereby at least partially conformally adapts to said structure stamp (2, 2') after said at least partial releasing of said fixation.

3. 3. The method according to claim 1, further comprising at least partially releasing the substrate from the substrate receiving device (6) by means of a relative movement between the substrate receiving device (6) and the substrate (1, 1', 1'') and / or by means of a relative movement between the substrate receiving device (6) and the stamp receiving device (5, 5') and / or by means of capillary forces.

4. 4. The method according to claim 1, wherein the embossed mass (7, 7', 7'') is structured without pressure and / or without crimping, in particular by capillary forces.

5. 5. The method according to claim 1, further comprising: fixing the substrate (1, 1', 1'') with the embossed mass (7, 7', 7'') on the substrate receiving device (6) by means of at least one controllable fixing element (9, 9') arranged in the substrate receiving device (6), in particular by means of a vacuum and / or negative pressure, and / or releasing the fixing by means of at least one controllable fixing element (9, 9'), in particular by interrupting the negative pressure and / or by creating a positive pressure.

6. 6. The method according to claim 1, wherein the fixing of the substrate (1,1',1'') and the at least partial releasing of the fixing of the substrate (1,1',1'') are controlled, in particular by controlling at least one controllable fixing element (9,9'), and the structuring of the embossing mass (7,7',7'') and / or the releasing or peeling off of the substrate (1,1',1'') are performed at a predefined time after the contact of the structuring stamp (2,2') with the embossing mass (7,7',7'').

7. 7. The method according to claim 1, wherein the structure stamp (2, 2') is formed in such a way that after the at least partial release of the fixation, the embossing mass (7, 7', 7'') and / or the substrate (1, 1', 1'') conformally adapts to the structure stamp (2, 2') without external pressure, in particular by capillary forces.

8. 8. The method according to claim 1, further comprising holding the substrate (1, 1', 1'') by the embossing mass (7, 7', 7''), in particular by capillary forces, after the contact and / or after the at least partial release of the fixation.

9. 9. The method according to claim 1, wherein the microstructures and / or the nanostructures are produced in multiple layers, one on top of the other, and / or next to each other in a step-and-repeat process.

10. Method according to at least one of the preceding claims, wherein the thickness of said substrate (1,1',1'') is between 1 μm and 2000 μm, preferably between 10 μm and 750 μm, more preferably between 100 μm and 500 μm.

11. 11. The method according to at least one of the preceding claims, wherein the viscosity of the embossed mass (7, 7', 7'') is less than 100,000 cP, preferably less than 10,000 cP, more preferably less than 1,000 cP, most preferably less than 500 cP.

12. 12. The method according to claim 1, wherein the structure stamp (2, 2') has an embossed structure (3, 3') and / or is coated with an embossed structure (3, 3').

13. An apparatus for producing micro- and / or nanostructures, in particular for producing micro- and / or nanostructures by a method according to at least one of claims 1 to 12, comprising: - the substrate (1, 1', 1'') with the embossed mass (7, 7', 7'') can be fixed on a substrate receiving device (6), - the structure stamp (2, 2') is capable of contacting said embossing mass (7, 7', 7''); said fixing of said substrate (1, 1', 1'') is at least partially releasable, said embossing mass (7, 7', 7'') is curable, - said embossing mass (7, 7', 7'') is releasable from said structure stamp (2, 2'); Device.

14. One or more sensors that measure pressure, distance and / or temperature; and / or one or more actuators for adjusting the position of the stamp receiving device (5, 5') and / or the substrate receiving device (6), and Control unit, Equipped with the control unit controls at least one of the fixing elements (9, 9') and / or at least one of the actuators, in particular depending on values ​​measured by at least one of the sensors, so that a relative movement of the structure stamp (2, 2') with respect to the substrate (1, 1', 1'') with the embossing mass (7, 7', 7''), in particular disappearance or reduction of the distance between the structure stamp (2, 2') and the substrate (1, 1', 1''), is possible such that contact can be made in particular without pressure, 14. The apparatus of claim 13.

15. An article comprising microstructures and / or nanostructures, the microstructures and / or nanostructures being manufactured by a method according to at least one of claims 1 to 12 and / or by an apparatus according to at least one of claims 13 and 14.

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