Methods and apparatus for fabricating micro- and / or nano-structures

Abstract

A method and apparatus for fabricating micro- and / or nano-structures are disclosed.

Description

TECHNICAL FIELD

[0001] The present invention relates to an apparatus and a method for manufacturing micro- and / or nanostructures. BACKGROUND

[0002] In the prior art, micro- and / or nanostructures are manufactured using optical lithography and / or by means of imprint lithography. In recent years, imprint lithography has been gaining in importance. By means of imprint lithography, micro- and / or nano-sized structures can be imprinted into a material by means of a stamp. The material is applied to a stamping material on a substrate.

[0003] In recent years, such imprint procedures have gained in importance, since they can be implemented more quickly, more efficiently and at lower cost than many optical lithography procedures.

[0004] After deposition of the stamping material, the structured stamp is aligned relative to the substrate. Subsequently, the structured stamp and the substrate are brought into proximity to one another. The structures of the structured stamp are formed in the stamping material. Before the structured stamp is removed from the stamping material, the stamping material is cured. Curing is carried out by means of heating and / or by means of electromagnetic radiation.

[0005] In addition to modified or extended shadow mask aligners, there are also separate imprint apparatuses which have been designed for and are used in special embodiments. These apparatuses are mostly high-precision alignment systems which are capable of aligning a stamp and a substrate with a higher precision. Furthermore, these apparatuses are capable of generating a vacuum, of having special dispensing systems and the like.

[0006] Imprint techniques work with hard or soft stamps. In imprint lithography, so-called soft stamps are predominantly used, which are always preferred. The reason for this is that the stamps are easy to manufacture, the imprint procedure is efficient, the very good surface properties of the respective stamp material, the low manufacturing costs, the reproducibility of the imprinted products and, in particular, the fact that the stamps can be elastically deformed during imprinting and removal from the formed position. A stamp made of a polymer, in particular an elastomer with a micro- or nanostructured surface, is used in soft lithography for the manufacture of structures in the range from < nm up to > 1000 pm.

[0007] Elastomer stamps are manufactured as a negative of a master plate. The master plate stamp is a hard stamp made of metal, plastic and / or ceramic, which is manufactured once by means of a correspondingly expensive procedure. Any number of elastomer stamps can then be manufactured from the master plate. The modulus of elasticity of quartz amounts to approximately 100 GPa. In comparison, the modulus of elasticity of polymers (hard and soft polymers) is smaller by several orders of magnitude, so that the latter are referred to as rsoft (soft lithography) in comparison with quartz. Elastomer stamps enable a conformal uniform contact over large surfaces. They are relatively easy to separate from their master plate stamp and from the imprinted product. To ensure good separation of the stamp from the substrate, the stamp surface has a surface energy which is as low as possible. For example, an anti-sticking coating is often necessary or advantageous.

[0008] To perform a soft lithography process, the elastomeric stamp can be supported by a carrier. For example, glass carrier substrates with different thicknesses are currently used. When thick glass substrates are used, the elastomeric stamp at least partially loses its flexibility. On the other hand, the flexibility of the stamp can be controlled by the choice of the carrier. After the imprinting process, the use of rigid carriers generally makes it difficult to separate the stamp from the substrate.

[0009] Similarly, thin substrates according to prior art require a substrate carrier for improved handling. Soft lithography processes include, for example, micro- and / or nano-contact printing (μ / nCP) and nano-imprint lithography (NIL).

[0010] In the case of nano-imprint lithography, the curing of the imprint material can be performed by heating or by UV radiation. In both cases, the structured stamp is pressed into the imprint material. To enable a high resolution surface structuring, the structured stamp and the substrate are pressed together by a pressure. In the case of UV-NIL, it is possible to work with a lower contact pressure than in the case of thermal NIL and the process can be performed at room temperature. The most important parameters in the NIL process are the temperature (especially in the case of thermal NIL), the pressing pressure and the adhesion between the imprint material and the structured stamp.

[0011] Soft and slightly hard stamps, in particular elastomeric stamps, can be deformed during the nano-imprint process by the applied pressure. This deformation is pressure dependent. It can be expected that this deformation has a greater impact in the case of smaller structures and is more pronounced in the case of softer stamp materials. The deformation or distortion of the micro- and nano-structures caused by the contact pressure is found in the cured imprint material on the imprinted substrate and thus reduces the quality and reproducibility of the imprinting process.

[0012] If the structured stamp and / or the substrate are too hard, an external pressure, in particular a contact pressure, is required to achieve a conformal or seamless contact between the structured stamp with the stamp structures and the substrate with the imprint material. In the prior art, actuator devices are used which comprise separate controllable or adjustable actuators for acting on the structured stamp and / or the substrate for using for transferring the stamp structures and causing a force normal to the substrate contact surface.

[0013] Precisely in the case of larger areas, it is difficult to distribute the pressure uniformly over the entire contact surface and to compensate irregularities. As a result, a non-uniform structuring can occur in the imprinting.

[0014] A possible non-uniformity of the stamp surface also affects the quality of the imprinting process. Furthermore, gas inclusions during imprinting with pressure and the associated imprinting defects are known in the prior art.

[0015] NIL imprinting defects that can occur are, for example, cracks, irregularly filled mold structures (i.e., for example, air inclusions) and a non-uniform lacquer layer thickness.

[0016] Not generally capillary force lithography (CFL) is also one of the soft lithography processes and is based on the use of capillary forces to fill the mold structures without external pressure. CFL is described in detail by H. H. Lee in Adv. Funct. Mater. (2002) 12:405-413. An elastomeric stamp is brought into conformal contact with a substrate. However, to fill the cavities, the imprinting material must have a very low viscosity. Therefore, CFL is carried out at higher temperatures and / or the solvent fraction in the imprinting material is higher and usually a solvent atmosphere is required. In CFL, almost exclusively pure PDMS is used as a stamp material, because PDMS is permeable for solvents and gases. During imprinting with a PDMS stamp, the cavities are filled under the action of capillary forces and the solvent from the imprinting material can diffuse through the PDMS stamp to escape. Problems such as swelling of PDMS in solvent-based processes and significant swelling in thermal processes mean that CFL is carried out only on a laboratory scale and industrial implementation using a compression molding apparatus is unknown. Furthermore, the imprinting material is usually thermally cross-linked in CFL.

[0017] For example, in US 7,442,336 B2, an apparatus and a method for imprinting a substrate using an imprinting material are described in detail, in which the substrate and the stamp are slowly brought together to a defined distance, so that the intermediate space is filled with the imprinting material due to capillary forces. External forces are kept as small as possible, which depends on the properties of the imprinting material, the thickness of the layer to be imprinted and the size of the substrate surface.

[0018] In US 8,871,048 B2, a flexible elastomeric stamp is used, so that the external pressure can be kept as low as possible.

[0019] Capillary micro-molding (MIMIC) also uses capillary forces to manufacture structures with a PDMS stamp. However, in MIMIC, a PDMS stamp with a relief structure is pressed onto a substrate. As a result, three-dimensionally structured hollows are produced between the stamp and the substrate. A monomer solution is applied to the front side of the stamp, which then fills the capillaries spontaneously. After curing, the stamp can be removed from the substrate. The three-dimensionally structured polymer remains on the substrate.

[0020] In the prior art, the elastic properties of soft stamps cause deformations or distortions of micro- and nanostructures to be particularly problematic. Deformations and distortions of micro- and nanostructures caused by contact pressure are found in the cured imprinting material on the imprinted substrate and thus reduce the quality and reproducibility of the imprinting process.

[0021] The soft stamp can be deformed during the nano-imprint procedure due to the applied pressure. In particular, this deformation is pressure dependent. Furthermore, gas inclusions and associated imprint defects when imprinting with pressure are known in the prior art.

[0022] If the structured stamp and / or the substrate is too hard, an external pressure (i.e. contact pressure) is required to achieve a conformal, seamless contact between the structured stamp and the substrate with the imprint material. Thus, a pressure dependent deformation can occur, which reduces the quality of the imprint procedure.

[0023] Therefore, the problem of the present invention is to specify a device and a method and a substrate which at least partially, in particular completely, eliminate the disadvantages mentioned in the prior art. [SUMMARY]

[0024] This problem is solved by the features of the independent claims. Advantageous embodiments and developments are given in the dependent claims. All combinations of at least two features given in the [SUMMARY], the [DETAILED DESCRIPTION], the [CLAIM] and / or the [DRAWINGS] are also within the scope of the present invention. Within the value ranges, values which lie within the limits are also considered to be disclosed as limit values and can be claimed in any combination. As long as features disclosed with respect to the device can also be considered features of the method, the latter should also apply to the method according to the device and vice versa.

[0025] In the following, structuring and imprinting are to be understood to mean the production of micro- and / or nano-structures. In particular, no contact pressure should occur in the imprinting.

[0026] The present invention describes a method and a device for producing micro- and / or nano-sized structures. The present invention is based, inter alia, on the idea of solving the aforementioned manufacturing technical problem by using a very thin, in particular flexible, substrate and using capillary forces. After the contact between the imprint material and the structured stamp, the fixing of the substrate is preferably at least partially cancelled, preferably by means of at least one controllable fixing element, thus preferably starting the imprinting procedure.

[0027] Therefore, the present invention is, inter alia, related to a method and a device for conformally contacting a structured stamp and an imprint material without using an external pressure or without contact pressure of the structured stamp and the imprint material in the imprinting procedure.

[0028] Therefore, the present invention is related to a method for producing micro- and / or nano-structures, having at least the following steps in the following sequence:

[0029] a) fixing a substrate with an imprint material on a substrate holding device,

[0030] b) contacting a structured stamp with an imprint material,

[0031] c) at least partially canceling the fixing of the substrate,

[0032] d) solidifying the imprint material,

[0033] e) removing the imprint material from the structured stamp.

[0034] Furthermore, the invention relates to a device for manufacturing micro- and / or nanostructures using the above-mentioned method, wherein a substrate with an imprint material can be fixed on a substrate holder device, and wherein a structured stamp can be brought into contact with the imprint material, and wherein the fixing of the substrate can be at least partially canceled, and wherein the imprint material can be solidified, and wherein the imprint material can be removed from the structured stamp.

[0035] Furthermore, the invention relates to an article with micro- and / or nanostructures, wherein the micro- and / or nanostructures are manufactured using a method according to the invention and using a device according to the invention.

[0036] In a preferred embodiment of the invention, it is provided that the substrate is flexible and can thus be adapted to the structured stamp at least partially, in particular after canceling the fixing or during structuring of the imprint material. In particular, the substrate has a small thickness and / or consists of a part flexible material, so that it can advantageously partially assume the structure of the structured stamp during manufacturing. The substrate can also be not adapted or completely adapted to the structured stamp. After solidification of the imprint material, the substrate with the solidified imprint material forms in particular a unit. Thus, the substrate can advantageously assist the imprinting process and prevent imprinting defects. Furthermore, a thin flexible substrate can deform during the process. In particular, the substrate can be advantageously attracted in a conformal manner towards the structured stamp by the action of capillary forces and thereby deformed. In addition, a better uniform contact during manufacturing is achieved by the flexibility. The flexibility of the substrate advantageously enables a careful and uniform imprinting without imprinting defects. By canceling the fixing, an additional degree of freedom is advantageously obtained, so that the thin and flexible substrate (in particular due to the action of capillary forces) assists the process in a desired manner. After canceling the fixing, the substrate is freely located on the substrate holder device. Due to the attraction of the imprint material and the substrate towards the structured stamp, it is also conceivable that the substrate is partially or completely peeled off from the substrate holder device, in particular by capillary forces. In particular, due to the flexibility of the substrate, no external pressure is required to transfer the structure to the imprint material. Thus, in particular, the substrate can compensate irregularities, so that the quality of the imprinting process is further improved.

[0037] In another advantageous embodiment of the application, it is provided that after at least partial cancellation of the fixing of the substrate, the substrate is at least partially detached from the substrate holding device, in particular by relative movement of the substrate holding device and the substrate and / or by relative movement of the substrate holding device and a stamp holding device and / or by capillary forces. In particular, the detachment can result in a spacing between the substrate and the substrate holding device. However, it is also conceivable that the cancellation of the fixing does not result in a detachment or a spacing. Furthermore, a spacing between the substrate and the substrate holding device can also be generated after at least partial cancellation of the fixing, in particular by means of an actuator. The spacing generated by the actuator is advantageously adapted to the process, in particular to the material properties. In particular due to the surface tension and the capillary forces, the substrate continues to adhere to the imprint material or is attracted towards the structured stamp, so that a degree of freedom of the substrate is also advantageously generated. Further forces, in particular gravitational forces, can act during the imprinting process, corresponding to the arrangement of the substrate holding device relative to the stamp holding device. In particular, the spacing can also be generated partially during the contact, in particular by means of an attractive force exerted on the substrate due to the capillary forces acting on the imprint material. However, preferably, a spacing is generated only after at least partial cancellation of the fixing. Due to the spacing, the reproducibility and the efficiency of the imprinting process, in particular of a plurality of imprinting steps carried out simultaneously and / or in parallel, can be advantageously improved. In addition, the substrate is able to deform and is adapted to the structured stamp due to the degree of freedom obtained. In particular, imprinting defects can thus be prevented.

[0038] In another advantageous embodiment of the application, it is provided that the structured stamp is a hard stamp or a soft stamp. In particular, the structured stamp can comprise a soft or hard imprint structure. In particular, a hard stamp is to be understood as meaning a master stamp. Thus, soft stamps and microstructures and / or nanostructures can be manufactured efficiently and cost-effectively using processes, in particular by selecting suitable process parameters and technically suitable manufacturing materials. Furthermore, a deformation of the structured stamp, in particular of the imprint structure of the structured stamp, can be prevented and uniform and reproducible imprinting can be carried out by suitable selection of the structured stamp.

[0039] In another advantageous embodiment of the application, it is provided that the structured imprint material is structured under the absence of pressure and / or the absence of contact pressure, in particular by means of capillary forces. Thus, a deformation of the structured stamp can advantageously be reduced, in particular prevented. Furthermore, the reproducibility of the imprinting process is thus increased and imprinting defects can be prevented. In addition, the method is more efficient and more cost-effective. The advantageous production of structures in the absence of external pressure can advantageously improve the material properties of the imprint material after solidification, such as, for example, strength values or surface properties. In addition, the substrate can advantageously be held after detachment. The advantages of the method also apply to the production of microstructures and / or nanostructures, since the smaller the size of the structures, the stronger the capillary forces act. Thus, the imprinting can be carried out in the absence of mechanical pressure, wherein the imprint material is advantageously received by the structures and can thus be particularly suitable for the structures. Advantageously, only the structured stamp, in particular a stamp surface of the imprint structure, needs to be touched or wetted when the imprint material and the structured stamp come into contact.

[0040] In another advantageous embodiment of the application, it is provided that the substrate with the imprint material is fixed on the substrate holder by means of a controllable fixing element arranged in the substrate holder, in particular by means of a vacuum and / or negative pressure, and / or the fixing is cancelled by at least one controllable fixing element, in particular by means of switching off the negative pressure and / or by means of generating an overpressure. The at least one fixing element can advantageously fix the substrate on the substrate holder, in particular at specific points. In particular, the fixing element can be a vacuum track arranged arbitrarily or set into the surface of the substrate holder, in particular in a circular or spiral shape. The fixing element can preferably generate an overpressure and / or a negative pressure. In particular, the forces resulting therefrom can be introduced arbitrarily onto the substrate, in particular on the side of the substrate facing the substrate holder. In particular, a curvature of the substrate can thus be generated. The substrate is fixed by means of a negative pressure, for example, at the edge of the substrate holder and an overpressure is generated by the other fixing elements, wherein the substrate is advantageously lifted in particular in the center. In this way, the contact points can be adjusted in particular during the contact. In addition, the at least one fixing element can advantageously prevent imprinting defects, in particular gas inclusions, by means of a technically advantageous and controlled part fixing or cancellation of the fixing. During the cancellation of the fixing, the fixing elements can also release the substrate individually and / or in groups in a specific sequence. Thus, the production of the structures can advantageously be started, in particular in specific regions. The fixing elements are preferably designed such that the cancellation of the substrate with the solidified imprint material from the structured stamp can be assisted by the fixing elements. The imprinting process can advantageously be started by the fixing elements. During the release or loosening of the substrate, in particular, capillary forces can advantageously act on the imprint material and / or the substrate. By means of the fixing elements, a careful and uniform production of the substrate is achieved in particular. In addition, the removal of the substrate can also be carried out in a particularly careful and advantageous manner. The substrate holder and the substrate preferably have the shape of a wafer.

[0041] In another advantageous embodiment of the application, it is provided that the fixing of the substrate and the at least partial release of the fixing of the substrate is controlled (in particular by controlling at least one controllable fixing element) such that the structured imprinting material and / or the release or detachment of the substrate takes place at a certain time after the structured imprinting material has been brought into contact with the imprinting material. The at least one fixing element is preferably controlled by a control unit and thus advantageously influences the time of the release of the fixing of the substrate and thus the detachment or the time of the release of the substrate. In particular, it can be provided that the release of the fixing begins at different points by a plurality of controllable fixing elements. In particular, the time and the position of the release of the fixing can thus be advantageously controlled. The control unit preferably controls the at least one fixing element depending on a value (in particular a value provided by a sensor).

[0042] In another advantageous embodiment of the application, it is provided that the structured imprinting element is designed in such a way that after the at least partial release of the fixing the imprinting material and / or the substrate is adapted or attracted to the structured imprinting element in a conformal manner without external pressure (in particular by capillary forces). The structured imprinting element (in particular the imprinting structures of the structured imprinting element) is designed in such a way that the structure is advantageously transferred to the imprinting material (in particular by capillary forces). In particular, the contact surface of the structured imprinting element (which touches the imprinting material during the contact) is designed in such a way that a uniform contact over the entire area is possible, in particular. Advantageously, the structures or recesses and / or protrusions of the imprinting structures of the structured imprinting element are configured in such a way that the structuring can take place without pressure. In particular, the imprinting structures to be transferred are designed in such a way that after the release of the fixing the substrate can be adapted to the structure conformally. Advantageously, the structured imprinting element is also designed for an advantageous easy removal. In particular, the structured imprinting element or the imprinting structures can be reused. Thus, the process can be implemented efficiently and repeatedly in succession by using the same structured imprinting element.

[0043] In another advantageous embodiment of the application, it is provided that after the contact and / or after the at least partial release of the fixing the substrate is held by the imprinting material (in particular by capillary forces and / or surface tension). Thus, after the release of the fixing the substrate is at least partially stuck due to the imprinting material on the structured imprinting element. In particular, due to the capillary forces acting on the imprinting material, a detachment of the substrate from the substrate accommodation device can occur. Due to the release of the substrate or due to the release of the fixing, the substrate continues to be held, wherein the substrate can advantageously be adapted to the structured imprinting element. In particular, the substrate can be advantageously freely and uniformly adapted to the imprinting structures. In addition, irregularities can thus be compensated. In particular, any gas inclusions present can escape. Advantageously, the quality of the imprinting process is thus improved.

[0044] In another advantageous embodiment of the application, it is provided that the micro- and / or nanostructures are produced on top of one another in a plurality of layers and / or next to one another in a stepwise repeated procedure. In particular, a multilayer construction is repeatedly carried out until the desired minimum flexibility of the substrate is no longer present. Thus, the procedure can be carried out more efficiently and more cost-effectively. Furthermore, different layers can be produced on top of one another. In addition, a plurality of functional structures can be produced on a large area or next to one another in a constant imprinting procedure. Thus, the most diverse products, in particular structured films, can be produced efficiently using the method. In particular, the structured stamp can advantageously be reused, since the electrical resistance of the structured stamp increases without contact pressure or the structured stamp can be used in a plurality of imprinting steps.

[0045] In another advantageous embodiment of the application, it is provided that the thickness of the substrate is between 1 μm and 2000 μm, preferably between 10 μm and 750 μm, more preferably between 100 μm and 500 μm. The flexibility of the substrate can be increased by using a thinner substrate. Thus, the substrate can still be preferably adapted to the imprinting structure and irregularities can be compensated. Furthermore, more layers can be produced on top of one another, since the required flexibility is provided in more imprinting steps.

[0046] In another advantageous embodiment of the application, it is provided that the viscosity of the imprinting material is less than 100,000 cP in total, preferably less than 10,000 cP, more preferably less than 1000 cP, most preferably less than 500 cP. By using an imprinting material with a lower cP value, in particular holding the substrate, the action of capillary forces and the conformal adaptation of the imprinting structure to the substrate and / or the imprinting material can be improved. Furthermore, a low cP value is advantageous for compensating irregularities. In addition, the flexibility of the substrate is used in an optimal manner and thus an improved imprinting quality is achieved. By a suitable viscosity of the imprinting material, the imprinting behavior of the imprinting material and in particular the holding of the substrate can be advantageously adjusted.

[0047] In another advantageous embodiment of the application, it is provided that the structured stamp comprises an imprinting structure and / or is coated with an imprinting structure. Thus, the imprinting stamp itself can comprise an imprinting structure or be coated with an imprinting structure, in particular individually adapted to the imprinting procedure. Thus, the imprinting behavior can be advantageously adjusted. In particular, the production of structures can be individually adjusted to the procedure by different imprinting coatings. Different imprinting structures can be transferred, in particular in a stepwise repeated procedure, for example, with an imprinting stamp.

[0048] In another advantageous embodiment of the application, it is provided that the device for manufacturing micro- and / or nanostructures can carry out the above-mentioned procedure, in particular, wherein a substrate with an imprint material can be fixed on a substrate holding device, and wherein a structured stamp can be brought into contact with the imprint material, and wherein the fixing of the substrate can be at least partially cancelled, and wherein the imprint material can be solidified, and wherein the imprint material can be removed from the structured stamp. The device can advantageously manufacture micro- and / or nanostructures, in particular, without additional pressure. Thus, the quality of the imprinting procedure is improved.

[0049] In another advantageous embodiment of the application, it is provided that the device further comprises one or more sensors for measuring pressure, distance and / or temperature and / or one or more actuators for adjusting the stamp holding device and / or the substrate holding device and a control unit, wherein the control unit controls at least one fixing element and / or at least one actuator, in particular, depending on a value measured by at least one sensor, wherein a relative movement of the structured stamp with respect to the substrate with the imprint material, in particular, a generation or reduction of a distance between the structured stamp and the substrate, can be carried out in such a way that the contact can be carried out, in particular, without pressure. In particular, it is provided that the control unit causes a contact of the structured stamp surface, in particular, of the imprint structure surface, by triggering the actuator based on the sensor value. Thus, the contact can advantageously take place without additional contact pressure. The actuator for generating the distance can be arranged on or engaged with any component, preferably with the substrate holding device and / or the stamp holding device. Thus, it can be advantageously ensured that the manufacturing of the micro- and / or nanostructures is carried out in an optimal way. In addition, the control unit is configured in such a way that the fixing of the substrate by the fixing element is advantageously carried out during the detachment and removal from the forming position, in particular, depending on the sensor value. This has the advantage that the quality of the procedure is improved and imprinting defects can be avoided.

[0050] In a less preferred embodiment of the application, it is provided that the control unit of the device causes a contact with additional contact pressure by triggering an actuator which can be controlled individually. The resultant pressure for transferring the stamp structure normal to the substrate contact surface is < 500 N. The structured stamp can be, for example, located on the entire area in the form of a wafer, or, alternatively, can have a defined area smaller than the substrate to be imprinted, in particular, in a step-and-repeat procedure. The resultant pressure for transferring the stamp structure normal to the substrate contact surface is, in particular, < 50 N / mm 2 , preferably < 25 N / mm 2 , more preferably < 10 N / mm 2 , best < 1 N / mm 2 , and most preferably < 0.1 N / mm 2 .

[0051] The substrate in the present application is very thin compared to the substrates described in the prior art. The carrier substrate is used to stabilize the substrate (or product substrate), or the carrier substrate or carrier plate or carrier film itself is thin and flexible. Thus, the substrate to be imprinted is very flexible, in particular is mounted flexibly.

[0052] The micro- and / or nano-imprinting process is carried out with a structured stamp, preferably an elastomeric structured stamp, preferably with a structured stamp in wafer form. The structured stamp is brought into contact with a substrate, preferably over the entire area, in particular with the imprinting material provided on the substrate.

[0053] The structured stamp and the substrate are each fixed on a holding device of an imprinting apparatus. The fixing of the substrate on the substrate holding device is preferably carried out by means of a vacuum or underpressure. After an alignment, the contact surfaces of the substrate and the structured stamp are brought into contact over the entire area. Once the structured stamp is in contact with the substrate, the fixing of the substrate, which is coated with the imprinting material, is released, in particular by interrupting the vacuum. By means of the capillary forces, the thin flexible substrate is drawn towards the structured stamp in a conformal manner. Due to the flexibility of the substrate and the freedom obtained by detaching the substrate, the substrate can be deformed and adapted to the structured stamp. Thus, a uniform contact is achieved during the imprinting.

[0054] The substrate and the substrate stamp are held together by means of the imprinting material between them by capillary forces. For this, at least the substrate, preferably the substrate and the structured stamp, must have a high flexibility. Due to the viscosity of the imprinting material, the intermediate spaces of the structured stamp are also completely filled with the imprinting material due to capillary action.

[0055] Due to the use of capillary forces, no additional external pressure and / or no contact pressure of the substrate with the structured stamp is necessary during the imprinting or the production of micro- and / or nanostructures. Thus, a deformation of the structures of the structured stamp caused by contact pressure is avoided, in particular prevented.

[0056] In particular, capillary forces are to be understood as meaning forces caused by surface tension and / or interfacial tension. Capillary rise and capillary depression can be used in particular during the production. Further forces can also occur during the production, such as adhesive forces and gravitational forces. Due to the small micro- and / or nanostructures, it can be advantageous to exploit the fact that the smaller the size of the structures, the greater the effect of the capillary forces or capillary pressure.

[0057] The flexibility of the substrate can compensate for irregularities of the structured stamp and / or of the substrate and also prevent further imprinting defects, such as those caused by air inclusions, so that the quality of the imprinting process is very high.

[0058] By using capillary forces, no additional external pressure and / or no contact pressure of the substrate with the stamp is necessary during imprinting, in particular. Thus, the device and the imprinting process are advantageously simplified, since no actuator device is necessary for the transfer force.

[0059] Due to the flexibility of the substrate and the freedom in detaching the substrate after contact without external pressure, the substrate can be deformed and can be adapted to the structured stamp, in particular.

[0060] A uniform conformal contact can be performed during imprinting. Thus, a very good stamping is obtained without imprinting gaps caused by non-contacting or poorly contacting areas during imprinting and subsequent curing.

[0061] The proposed invention prevents deformation of the micro- and / or nanostructures of the structured stamp caused by contact pressure.

[0062] The viscosity of the imprinting material is preferably between 1 cP and 100,000 cP, so that a wide selection of imprinting materials or imprinting lacquers and an optimization of the process with the best combination of substrate, stamp material and imprinting material is possible.

[0063] In particular, the imprinting material does not necessarily have a low viscosity. In particular, a solvent atmosphere is not necessary.

[0064] The contact and the imprinting can be performed, in particular, at ambient pressure, for example under an air or an inert gas atmosphere. Other (in particular, controlled) process pressures are also conceivable.

[0065] In particular, the contact and the imprinting can be performed at room temperature and at elevated temperatures.

[0066] The described method advantageously enables a high throughput and can reduce the unit cost per manufactured unit, in particular.

[0067] Imprinting of periodic and non-periodic micro- and nanostructures is possible.

[0068] Advantageously, an exact alignment is not absolutely necessary. The alignment of the substrate with the structured stamp before contact (for example only roughly or finely using a high-precision alignment system) can vary for each case.

[0069] Different types of flexible substrates can be used in the described method.

[0070] The imprinting or manufacturing can be performed using smooth surfaces and / or using rough surfaces. The roughness can vary for each case.

[0071] The imprinting or manufacturing can be performed, in particular, using flat surfaces and / or using curved stamp surfaces. Due to the flexibility of the substrate and the mobility in detaching the substrate after contact without external pressure, the substrate can be deformed and adapted to the stamp.

[0072] Both conductive and non-conductive UV-curable imprint materials can be used.

[0073] Both conductive and non-conductive heat-curable imprint materials can be used.

[0074] With the proposed invention, a multilayer imprint procedure can be implemented. A first imprinted and cured layer of a flexible substrate can be coated in a further step with a second imprint material, which is then imprinted and cured again. In particular, as long as there is still sufficient substrate flexibility, further layers can be envisaged. Furthermore, several imprint steps can be implemented in parallel and / or side by side to each other and combined with the substrates manufactured in the previous cases.

[0075] In the described method, the thickness of the imprint material on the substrate can be varied as required, so that both thin and thicker layers of imprint material can be imprinted or manufactured.

[0076] With the proposed invention, two working stamps for imprint lithography can be manufactured and also generally different types of imprint materials, which can be cured by heating or by electromagnetic radiation, in particular UV radiation, for structuring substrates. Preferably, UV-curable imprint materials are used.

[0077] The proposed invention can be used, in particular, for manufacturing the following products:

[0078] - 1D, 2D and / or 3D diffractive optical elements (DOEs),

[0079] - microfluidic components,

[0080] - lenses and lens systems,

[0081] - Fresnel lenses,

[0082] - biomedical elements,

[0083] - polarizers,

[0084] - nanostructured electrodes,

[0085] - IR waveguides,

[0086] - angular optical devices for virtual reality applications,

[0087] - fiber optic connections,

[0088] - working stamps for imprint lithography,

[0089] - and others.

[0090] Capillary action is caused, inter alia, by the surface tension of the liquid itself or the interfacial tension between the liquid and the solid surface. Capillary forces occur in the interaction between a solid surface and a liquid or between solids in the presence of particularly small amounts of liquid. The cohesion between the liquid molecules and the adhesion between the liquid molecules and the surface of the substrate and the substrate stamp, due to the coating of the latter with an imprint material, contribute to the fact that two surfaces remain in contact after contact, in particular without the action of external forces. Advantageously, thin flexible substrates are used, so that the capillary forces have a correspondingly strong effect and the substrate is attracted to the structured stamp in a conformal manner.

[0091] A further variant is that the thin coated substrate is detached from the substrate as soon as the structured stamp is brought into contact with the substrate. The fixing of the substrate coated with the imprint material is released, in particular by releasing the fixing, for example by interrupting the vacuum.

[0092] Due to the action of the capillary forces, the thin flexible substrate remains connected to the structured stamp in a conformal manner.

[0093] Due to the flexibility of the substrate and the freedom obtained by detaching the substrate from the substrate holding device, the substrate can be deformed and adapted to the structured stamp. Thus, uniform contact is achieved during the imprinting.

[0094] Due to the conformal contact, the intermediate spaces of the structured stamp are completely filled, in particular due to the viscosity of the imprint material and also due to capillary action. The capillary pressure, in particular, depends on the size of the structure.

[0095] The smaller the structure, the greater the capillary pressure. A high-resolution structuring in the lower nm range (< 50 nm) is possible, since the capillary pressure is greatest in this range.

[0096] Furthermore, imprint defects caused by the use of external contact pressure during the imprinting process are advantageously prevented.

[0097] Method

[0098] The substrate is very thin compared to substrates in the prior art. The carrier substrate is used to stabilize the substrate (or product substrate), or the carrier substrate or carrier plate or carrier film itself is thin and flexible. Thus, the substrate to be imprinted is very flexible.

[0099] The micro- and / or nano-imprinting process is carried out with a structured stamp, preferably an elastomeric stamp, in particular in the form of a wafer. The structured stamp is brought into contact with a substrate, preferably pre-coated over the entire area.

[0100] In particular, the structured stamp and the substrate are each fixed on a holding device of a press device. The fixing of the substrate on the substrate holding device is preferably carried out by means of a vacuum or underpressure. After an alignment, the contact surfaces of the substrate and the structured stamp are brought into contact over the entire area. Once the structured stamp is in contact with the substrate, the fixing is released, in particular by interrupting the vacuum, from the substrate coated with the imprint material. The release procedure can act over the entire area or along a predefined course. The fixing elements are correspondingly controlled.

[0101] If the substrate is detached from the holding device over the entire area after the contact has been made, the substrate continues to adhere to the structured stamp due to the capillary action (capillary forces) acting through the imprint material present between the substrate and the structured stamp. According to the invention, no additional external pressure is required for successful imprinting or production.

[0102] Due to the action of the capillary forces, the thin flexible substrate is attracted towards the stamp in a conformal manner. Due to the flexibility of the substrate and the freedom obtained by detaching the substrate, the substrate can be deformed and adapted to the stamp. Thus, uniform contact is achieved during the imprinting.

[0103] The substrate and the structured stamp are held together by means of the imprint material between them due to the capillary forces. For this purpose, at least the substrate must have a high flexibility. In particular, due to the viscosity of the imprint material, the intermediate spaces of the structured stamp are completely filled by the imprint material due to the capillary action.

[0104] Thus, the proposed invention prevents structural deformations of the structured stamp caused by contact pressure. Furthermore, the flexibility of the substrate can compensate for irregularities of the stamp and / or the substrate and also prevents further imprinting defects, such as those caused by air inclusions, so that the quality of the imprinting procedure is very high.

[0105] During the adaptation of the thin substrate to the structured stamp and the deformation, the gas present between the substrate and the structured stamp, in particular air or an inert gas, can be pushed out so that the imprinting can be carried out without gas inclusions. The inclusion of air or other gases can be prevented, in particular by an adjusted release of the fixing elements holding or fixing the substrate. A favourable detachment of the substrate can be carried out, in particular by a single release at the fixing elements, in particular a concentrated release along the wafer surface.

[0106] After the imprint material has solidified, the substrate can be fixed again on the holding device using a vacuum, if necessary, so that removal from the forming position can be carried out.

[0107] The method according to the invention for imprinting thin flexible substrates using a structured stamp with micro- and / or nano-structures, in particular comprises the following steps, in particular in the following sequence:

[0108] a) fixing the substrate and the structured stamp on corresponding holding means;

[0109] b) applying the imprint material on the substrate;

[0110] c) rough and / or fine adjustment of the substrate and the structured stamp;

[0111] d) starting the imprinting process by contacting the substrate with the imprint material with the structured stamp, in particular by relative movement of the substrate holding means and / or the stamp holding means, so that the substrate is attracted by capillary forces towards the structured stamp and a conformal contact is generated.

[0112] e) releasing the fixation of the flexible substrate from the substrate holding means once the contact is made. Due to the resulting freedom, the flexible substrate can deform and adapt to the structured stamp.

[0113] f) curing the imprint material;

[0114] g) re-fixing the imprinted substrate on the substrate holding means and removing the structured stamp and the substrate from the forming position.

[0115] The imprinting is preferably started after the contact surfaces of the substrate and the structured stamp are in contact with the imprint material and thus, in particular, after the capillary forces are applied by detaching the substrate.

[0116] After the release, the thin substrate is in particular no longer subjected to any fixation to the holding means and can thus adapt to the structured stamp.

[0117] The contact is preferably described as a contact over the entire area. Alternatively, the contact can be made from the edge or from the middle. In a further embodiment according to the application, for point-by-point contact, the curved structured stamp and / or the substrate is implemented by a bending member. The contact can advantageously be assisted by controlled fixation elements, in particular.

[0118] In another embodiment, a step-and-repeat process is implemented. The structured stamp is used in a step-and-repeat process in such a way that a repeating structure is applied to the circumference of an imprint roller. The device comprises a curing member for curing the imprinted substrate, in particular in sections, preferably using sections corresponding to the step-and-repeat process, in particular corresponding to a stamp area of the structured stamp.

[0119] Substrate, structured stamp and imprint material

[0120] The substrate and / or the substrate stamp is particularly flexible to achieve a conformal contact over the entire substrate surface or structured stamp surface. In a preferred embodiment, the substrate is very thin so that an advantageous flexibility is provided. The substrate is used without a carrier substrate, or the carrier substrate or carrier plate or carrier film itself is thin and flexible. Thus, the substrate to be imprinted is very flexible. The thin substrate is fixed on a holding means so that handling is facilitated.

[0121] The substrate can have any shape, preferably circular, rectangular or square, more preferably in the form of a wafer. The diameter of the substrate is more than 2 inches, preferably more than 4 inches, more preferably more than 6 inches, more preferably more than 8 inches, most preferably more than 12 inches. In particular, a substrate is understood to mean a wafer.

[0122] The thickness of the substrate is in particular between 1 pm and 2000 pm, preferably between 10 pm and 750 pm, more preferably between 100 pm and 500 pm.

[0123] The structured stamp can have any shape, preferably circular, rectangular or square, more preferably in the form of a wafer. The diameter of the structured stamp is preferably essentially identical to the diameter of the substrate.

[0124] For carrying out the soft lithography process, an elastomeric structured stamp is used as a standard, preferably a UV-transmissive polymer stamp.

[0125] Transparent elastomeric structured stamps for UV-NIL are made of, for example, polysiloxanes such as polydimethylsiloxane (PDMS), polyorganosilsesquioxane (POSS), perfluoropolyether (PFPE), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), ethylene tetrafluoroethylene, etc. Combinations of several materials and several layer systems are possible.

[0126] The structured stamp is preferably fixed on a carrier (English: backplane), in particular a plate, most preferably a glass carrier. Further conceivable materials for the carrier are polymers and / or metals. In particular, the carrier can also be a stamp carrier substrate.

[0127] On its imprinting side, the structured stamp has in particular a plurality of imprint structures, preferably distributed over the entire imprint area of the imprinting side, in particular regularly arranged. The size of the individual structures of the imprint stamp is in the micrometer and / or nanometer range. In particular, the size of the individual structures is less than 20 pm. In particular, the size of the individual structures is between 0.1 nm and 20 pm, preferably between 1 nm and 10 pm, more preferably between 1 nm and 5 pm, more preferably between 1 nm and 2 pm.

[0128] The structured stamp can comprise a positive and / or negative profile on the side facing the surface of the substrate to be processed. The structured stamp can also comprise imprint structures with different sizes.

[0129] In an alternative embodiment, the structured stamp is made of a hard UV-transmissive material such as, for example, glass, quartz or silicon dioxide. In this embodiment, the substrate has to have, inter alia, the required thin layer thickness and flexibility. In a further embodiment, the structured stamp is made of a hard material such as, for example, silicon, a semi-conductor material or a metal such as Ni or Ti.

[0130] In particular, the imprint material is cured by a chemical and / or physical process. In particular, the imprint material is cured by electromagnetic radiation and / or by temperature.

[0131] Curing is preferably carried out by electromagnetic radiation, in particular by UV radiation. In this case, if the imprint material is to be cured from the side of the structured stamp, the structured stamp preferably transmits the required electromagnetic radiation.

[0132] On the side of the structured stamp facing away from the imprint structure, a corresponding radiation source is preferably arranged. Thus, the structured stamp in particular transmits a wavelength range of between 5000 nm and 10 nm, more preferably between 1000 nm and 100 nm, more preferably between 700 nm and 200 nm, most preferably between 500 nm and 250 nm.

[0133] The optical transparency of the structured stamp is greater than 0.01 %, preferably greater than 20 %, more preferably greater than 50 %, most preferably greater than 80 % and most preferred greater than 95 %.

[0134] The viscosity of the imprint material is preferably between 1 cP and 100,000 cP, so that a wide selection of imprint material / imprint lacquer and an optimal combination of substrates, stamp materials and processes for imprint material are possible. In particular, the viscosity is less than 100,000 cP, preferably less than 10,000 cP, more preferably less than 1000 cP, most preferably less than 500 cP.

[0135] In particular, the imprint material is applied on the entire area or as droplets on the substrate or the structured stamp at defined distances. The imprint material is preferably applied on the substrate. The application of the imprint material can take place before or after fixing the substrate. According to the application, more imprint material or more droplets can also be used to define the area, depending on the topology of the structured stamp or depending on the size of the structure. The application of the imprint material can be carried out, for example, using a metering device with a nozzle which can be arranged between the structured stamp and the substrate.

[0136] In a further embodiment, the application can be used in combination with existing industrial coating processes such as, for example, spin coating processes. The coating can be carried out in a separate module separately from the imprint process. Thus, the coating of the substrate is fast, defect-free, over the entire area, particle-free and standardized. In particular, this leads to production advantages and cost reductions.

[0137] Device

[0138] Specifically, the present invention relates to the described method and an apparatus for transferring a structure (specifically, a microstructure or a nanostructure) from a UV-transmittable structured imprint to a flat side of a substrate (specifically, coated over the entire area), wherein a substrate holder accommodates the substrate on a substrate receiving surface and on a structured surface of the structured imprint, which is parallel to and can be configured to face the substrate contact surface.

[0139] The device can be preferably installed in a processing chamber that is hermetically sealed relative to the surrounding environment. Therefore, the processing chamber can be evacuated and / or vented with any gas or gas mixture. The processing chamber can be evacuated to a pressure of less than 1 bar, preferably less than 10 mbar, and more preferably less than 5 mbar.

[0140] In a preferred embodiment, the method according to the invention is carried out under ambient pressure (e.g., in an air or inert gas atmosphere).

[0141] Specifically, the processing chamber can be filled with any gas or gas mixture. This is particularly advantageous when the imprinting is not intended to be performed under a vacuum. One possible, but not the only, reason for forgoing a vacuum is the high volatility of the imprinting material at low ambient pressures. The slight volatility characterized by high vapor pressure can decisively cause contamination of the processing chamber.

[0142] Next, the gas used should interact with the imprinting material as little as possible. Preferably, it should be filled with an inert gas that does not interact with the imprinting material.

[0143] Contact and imprinting can be performed at both room temperature and high temperature. The device according to the invention has components suitable for temperature regulation and heating.

[0144] In another embodiment, the contact between the substrate and the structured mold is particularly critical because defects can occur here and a reproducible adjustment accuracy cannot be met. The device can, for example, utilize SVA ( The View Alignment method combines high-precision alignment of different layers above and below each other, adjusted imprinting, etc. In the critical step of aligning the contact surfaces of the substrate and the (nano)structured mold, it is desirable to have more accurate adjustment accuracy or offset of less than 100 μm, especially less than 10 μm, preferably less than 1 μm, best less than 100 nm, and most preferably less than 10 nm.

[0145] The substrate and the structured stamp are brought together in the described device in an aligned manner, so that the approach and adjustment of the micro- and / or nano-imprint stamping process is carried out in a controlled manner. According to the patent specification EP 2612109 B 1, the device preferably comprises a system for contactless wedge error compensation between the stamp alignment parallel and the substrate, wherein the approach member serves to approach a first surface towards a second surface in a direction of translation (T) transverse to the accommodation surface of the accommodation device until the end position.

[0146] In another embodiment, a coarse alignment is sufficient. In particular, an exact alignment is not necessary, since the thin substrate can be adapted to the structured stamp due to its flexibility and due to a given mobility from the substrate holder.

[0147] The substrate and the structured stamp are fixed on an accommodation device (English: chunk). In particular, a flat accommodation surface or holding surface for holding and fixing determines the accommodation device. The accommodation device of the substrate and the structured stamp is preferably a vacuum sample holder. It is also conceivable to use an electrostatic sample holder, to use a sample holder with magnetic or electrical fixing, to have a sample holder with variable adhesion or with suitable mechanical clamping.

[0148] In a preferred embodiment, the substrate and the structured stamp are fixed by a negative pressure or vacuum on a flat hardened surface, in which vacuum tracks are milled. The substrate accommodation device has vacuum tracks over the entire surface or over an outer region of the surface. The negative pressure channels preferably run concentrically, in particular in a circular shape, to a center Z of the accommodation device, in particular around the entire circumference. Thus, a particularly uniform fixing is advantageously achieved.

[0149] The accommodation device, in particular the substrate accommodation device, preferably has vacuum tracks only over an outer region of the surface, so that the substrate is only partially fixed, in particular at the edges. In particular, there is the possibility to completely release the substrate and / or the structured stamp from the accommodation device. For this, the fixing of the accommodation device, in particular the holding vacuum, is removed. The fixing elements, which act using a negative pressure for fixing, can also act using an overpressure for detaching the substrate. According to an advantageous embodiment, the accommodation device can comprise a second vacuum region to ensure that the substrate is fixed over the entire area after the imprinting and curing process.

[0150] If the fixing elements are provided as vacuum elements, they can generate a pressure of less than 1 bar, preferably less than 0.1 mbar, more preferably less than 0.01 mbar, best of all less than 0.001 mbar and most preferably less than 0.0001 mbar. In particular, the fixing elements can be controlled individually or in groups.

[0151] The holding device according to the application can alternatively or additionally comprise sensors by means of which physical and / or chemical properties between the holding device and the substrate can be measured. Such sensors are, for example, temperature sensors, pressure sensors or distance sensors. It is also conceivable for a plurality of different types of sensors to be incorporated. Furthermore, sensors can also be arranged on other parts of the device. For example, a distance sensor or a pressure sensor can be arranged between the holding devices. In particular, the distance and / or a force between the substrate with the imprint material and the stamp or the stamp structure can be measured.

[0152] Furthermore, the contour of the holding surface can be recessed relative to the holding plane of the holding surface as required, so that a reduction in the size of the holding surface or a change in its concavity is produced. Thus, substrates (product substrates) which are structured or treated on both sides can also be used.

[0153] In a further embodiment, the holding device is configured such that the substrate and / or the structured stamp can be heat treated over the entire area or in sections. The holding device can heat treat in a temperature range of between -100°C and 500°C, preferably between -50°C and 450°C, more preferably between -25°C and 400°C, optimally between 0°C and 350°C.

[0154] The embodiments of the substrate holding device according to the application are also capable of handling a substrate and a liquid layer thereon. In particular, the liquid layer is a liquid imprint lacquer or imprint material which is located in the interface during the contact.

[0155] In particular, the imprint material is applied over the entire area or as droplets at a defined distance on the substrate or the structured stamp. The imprint material is preferably applied on the substrate. More imprint material or more droplets can also be used to define the area, depending on the topology of the substrate or the structured stamp. In particular, the application of the imprint material can be carried out using a metering device with a nozzle which can be arranged between the structured stamp and the substrate.

[0156] In a further embodiment, the method can be used in conjunction with existing industrial coating processes, such as, for example, spin coating processes. The coating can be carried out in a separate module separately from the imprint process. Thus, the coating of the substrate can be fast, defect-free, over the entire area, particle-free and standardized. In particular, this is accompanied by a yield advantage.

[0157] In another embodiment, the holding device preferably comprises in the center a device for bending the structured stamp, in particular only partially fixed, and / or the substrate. The device for bending refers to a bending element. In particular, the bending element is a nozzle through which a fluid, preferably in the form of a gas, can exit to create, for example, an overpressure between the structured stamp and the holding device, which bends the structured stamp. Due to the fact that the structured stamp is preferably fixed at the circumference by the vacuum to the holding device, a curvature of the structured stamp results.

[0158] According to the present application, the imprinting is started after the contact, preferably over the entire area of the contact surfaces of the substrate and the structured stamp with the imprinting material, and thus after the start of the capillary forces, in particular due to the detachment of the substrate.

DRAWINGS

[0159] Further advantages, features and details of the present application are shown from the following description of preferred examples and by means of the drawings. In the drawings, schematically:

[0160] Figure 1a a cross-sectional view of a device in a first embodiment of the method, in which the structured stamp and the substrate holder are brought close to each other without external contact pressure until an end point,

[0161] Figure 1b a cross-sectional view of a device in a first embodiment of the method, in which the structured stamp and the substrate holder are brought close to each other without external contact pressure until an end point,

[0162] Figure 1c a cross-sectional view of a device in a first embodiment of the method, in which the structured stamp and the substrate holder are brought close to each other without external contact pressure until an end point,

[0163] Figure 1d a cross-sectional view of a structured stamp holding device in a first embodiment of the method after imprinting or production, in which the curable imprinting material is cross-linked or cured in the stack, in particular through the transparent structured stamp, by UV light.

[0164] Figure 1e a cross-sectional view of a device after imprinting, in which the structured stamp and the substrate have been removed from the forming position after the imprinted substrate has been refixed on the substrate holding device,

[0165] Figure 2 a cross-sectional view of a device in a first embodiment of the method, in which the structured stamp and the substrate holder are brought close to each other without external contact pressure until an end point,

[0166] Figure 3aA second cross-sectional view of one of the apparatuses illustrating the first embodiment of the method, wherein the substrate is detached from the substrate receiving device by interrupting the vacuum in the vacuum track and is adhered to the structured mold in a conformal manner due to capillary forces.

[0167] Figure 3b The image shows a cross-sectional view of one of the apparatuses after the imprinting process, where the removal of the structured mold and substrate from the forming position has occurred after the imprinted substrate has been reattached to the substrate receiving apparatus.

[0168] Figure 4a A cross-sectional view of an apparatus according to a second embodiment of a method according to the present invention is shown.

[0169] Figure 4b A cross-sectional view of one of the apparatuses in a second embodiment of the method for imprinting and curing.

[0170] Figure 4c A cross-sectional view of one of the apparatuses in a second embodiment of the method after removal from the molding position.

[0171] Figure 4d A cross-sectional view of one of the apparatuses in a second embodiment of the method in the second repeating step of a step-by-step repeating imprinting process.

Detailed Implementation Methods

[0172] In the diagram, identical components or components with the same function are labeled with the same element symbol. The diagram is not shown to scale for ease of representation.

[0173] Figure 1a A cross-sectional view of one of the devices in a first embodiment is shown. Specifically, Figure 1a Displaying receiving devices 5 and 6 for accommodating one of the structured mold 2 and substrate 1. Specifically, the receiving surfaces of receiving devices 5 and 6 are adapted to the size and circumferential contour of the structured mold 2 and substrate 1.

[0174] In a preferred embodiment, from Figures 1a to 1e The structured mold 2 is an elastomer soft mold 2. The elastomer structured mold 2 achieves conformal and uniform contact on a large surface. To ensure good separation between the structured mold 2 and the substrate 1, the mold surface has the lowest possible surface energy.

[0175] The elastomeric structured mold 2 is supported by a carrier or mold carrier substrate 4 as needed. In another embodiment, glass carrier substrates of different thicknesses are used. Due to the use of a mold carrier substrate 4, the elastomeric structured mold 2 at least partially loses its flexibility. On the other hand, the flexibility of the structured mold 2 can be controlled by selecting the carrier 4. In an alternative embodiment, the carrier 4 can be a plate. In a third embodiment, the carrier 4 is not required. The structure of the structured mold 2 is not limited to those derived from... Figures 1a to 1eExamples of implementation.

[0176] The structures 3 and 3' of the structured impression 2 have dimensions in the micrometer and / or nanometer range. In a preferred embodiment, the structured impression 2 is fixed by vacuum or negative pressure via a vacuum track 8 of a vacuum device (not shown). Figures 1a to 1e In one embodiment, a negative pressure is applied to fix the structured impression while a plurality of vacuum tracks 8 operate concentrically and cover the receiving surface of the impression receiving device 5 for receiving the structured impression. In an alternative embodiment, the vacuum tracks 8 are located only in the region of one side edge of the receiving surface of the impression receiving device 5. In this alternative embodiment, only an outer annular section of the receiving surface of the impression receiving device 5 is provided for fixing the structured impression 2 by means of the vacuum tracks 8.

[0177] According to Figures 1a to 1e In one preferred embodiment, substrate 1 is very thin compared to substrates in the prior art, thus providing flexibility. In this first embodiment, a carrier-free substrate is used to stabilize substrate 1 or the product substrate. The thin substrate 1 is fixed to a receiving device 6 to facilitate handling. In an alternative embodiment, a carrier (not shown) is used to stabilize the thin substrate 1. 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 thinner and therefore has sufficient flexibility. Thus, the substrate to be imprinted is flexible.

[0178] In a preferred embodiment, from Figures 1a to 1e The substrate is a very thin substrate. Specifically, the thickness of the substrate 1 is between 1 μm and 2000 μm, more preferably between 10 μm and 750 μm, and even more preferably between 100 μm and 500 μm.

[0179] The thicknesses of the structured mold 2, substrate 1, and imprinting material 7 are not shown to scale in the figure for ease of representation.

[0180] From Figure 1a The receiving surface of the substrate receiving device 6 is at least substantially adapted to the size of the substrate 1. In a preferred embodiment, the substrate 1 is fixed by vacuum or negative pressure via a vacuum track 9 of a vacuum device (not shown).

[0181] According to Figures 1a to 1e In one embodiment, a negative pressure is applied to fix the substrate 1 while a plurality of vacuum tracks 9 operate concentrically and cover the receiving surface of the mold receiving device 6 for receiving the substrate 1. Specifically, the fixing members are also constructed as individually controllable fixing elements that are particularly uniformly distributed on the receiving surface and divided into several zones. Figure 1a and Figure 1bIn particular, the edge region extends to 1 / 2 of the radius of the receiving surface, preferably up to 1 / 4 of the radius.

[0182] According to Figure 1a The substrate has been coated over the entire area with an imprint material 7. In a preferred embodiment, the method is used in conjunction with an existing industrial coating process such as, for example, a spin-coating process. The application of the layer is carried out, inter alia, using spin-coating, spray-coating or inkjet processes and dip-coating or roll-coating processes. The coating can be carried out in a separate module from the imprint process.

[0183] In an alternative embodiment according to Figure 2 In this embodiment, the imprint material 7' is applied to the substrate 1 as droplets at defined distances. The volume of the droplets is precisely measured and controlled such that an intermediate layer thickness of a possible intermediate layer between the structured recesses of the imprint structure and the surface of the substrate is adjusted. The intermediate layer thickness is as small as possible. Preferably, the intermediate layer thickness is between 50 μm and 0.01 nm, more preferably between 10 μm and 0.01 nm, most preferably between 1 μm and 0.01 nm.

[0184] In an embodiment, the substrate receiving device 6 is also capable of handling the substrate 1 and a liquid layer thereon. In particular, the liquid layer is a liquid imprint lacquer or imprint material 7, 7' located in the interface during the contact.

[0185] Figure 1b The device in a further process step is shown. After an alignment, the contact surfaces of the substrate 1 and the structured stamp 2 are brought closer together and contact is made over the entire area.

[0186] In an embodiment according to the application, a relative movement is made between the structured stamp 2 and the substrate 1, 1'. Preferably, only one of the receiving devices 5, 6 is moved. Preferably, only the structured stamp 2 is advanced relative to the static substrate receiving device 6.

[0187] In a step according to Figure 1b In a step according to the application in which the structured stamp 2 and the substrate 1 are brought into contact, only the securing means in the edge region of the substrate receiving device 6 are used. Once the structured stamp 2 and the substrate 1 are in contact, the securing is released from the substrate 1 coated with the imprint material 7, 7' by interrupting the vacuum. By reducing the negative pressure at the receiving surface, the detachment of the substrate 1 can be carried out in a controlled manner. The securing elements are thus controlled. The structured stamp 2 remains unchanged, secured to the stamp receiving device 5.

[0188] After detachment, according toFigure 1c The substrate 1 continues to adhere to the structured mold 2 due to capillary action or the capillary force exerted by the imprinting materials 7, 7' present between the substrate 1 and the structured mold 2, and the imprinting process begins over the entire area. According to the present invention, no additional external pressure is required for successful imprinting or manufacturing. According to the present invention, simply bringing the receiving devices 5, 6 closer together achieves a distance H (see...) Figure 2 Reduced to a precisely defined distance H E This allows the molding process to begin without the use of additional external pressure. Specifically, the final distance H... E The thickness is less than 100 μm, preferably less than 10 μm, most preferably less than 500 nm, and most preferably less than 100 nm. Due to capillary forces, the thin, flexible substrate 1 is attracted toward the structured mold 2 in a conformal manner. Because of the flexibility of the substrate 1 and the degrees of freedom gained through removing the substrate 1, the substrate 1 can be deformed and adapted to the structured mold 2. Therefore, uniform contact is achieved during the imprinting process.

[0189] Figure 1c An apparatus is shown that has a UV-transmitting structured mold 2 mounted on a mold receiving device 5, wherein the substrate 1 on the structured mold 2 and the imprinting material 7 therebetween are held together by capillary force. For this purpose, the substrate 1 must have at least a high degree of flexibility. Due to the viscosity of the imprinting material 7, the intermediate space of the structured mold 2 is also completely filled due to capillary action.

[0190] According to Figure 1c In one embodiment, after the fixation to the substrate receiving device 6 is interrupted and after the action of capillary force, the substrate 1 is no longer located on the receiving surface of the substrate receiving device 6. In a second embodiment (not shown in the figure), the substrate 1 remains located on the receiving surface of the substrate receiving device 6, without being (actively) fixed by the fixing member and without the action of capillary force. Whether there is still contact between the substrate 1 and the receiving surface of the substrate receiving device 6 after the substrate fixation is released by the fixing member 9 depends on a plurality of process parameters ab, such as (for example) the amount and viscosity of the imprinting materials 7, 7′, the size of the structure 3, 3′ of the structured mold 2, the adjustment of the final distance HE, etc.

[0191] In an alternative embodiment (not shown in the figures), the structured mold 2 is located on the lower receiving device and the substrate 1 is located on the upper receiving device. After separation, the substrate 1 continues to adhere to the structured mold 2 due to capillary forces (also caused by additional gravity) exerted by the imprinting material present between the substrate 1 and the structured mold 2, and is located on the imprinting material 7 applied to the structured mold 2 as droplets at defined distances.

[0192] In all the embodiments shown, no external pressure (specifically, no contact pressure) is required to achieve a conformal or seamless contact between the structured mold 2 and the substrate 1 having the imprinting material 7. The device has the advantage of not requiring the use of an actuator to apply a force to the mold 2 and / or the substrate 1 using a force for transferring the mold structure 3 and resulting in a force orthogonal to the substrate contact surface.

[0193] The method prevents deformation of structure 3 of the structured mold 2 caused by contact pressure. Furthermore, the flexibility of the substrate 1 can compensate for the irregularities of the structured mold 2 and / or the substrate 1 and also prevent further imprinting defects (such as imprinting defects caused by air inclusions), thus the quality of the imprinting process is very high.

[0194] According to Figure 1d In the next step, the direct cross-linking of the curable imprinting material 7 (specifically, a photoresist or varnish) is carried out by UV light 10. Generally, curing can be achieved by electromagnetic radiation, heat, electric current, magnetic field, or other methods. Preferably, curing is carried out through a transparent impression receiving device 5 and a transparent structured impression 2. It is also conceivable to cure the imprinting material 7 using a radiation source in or on the impression receiving device 5.

[0195] According to Figure 1e In the final step of the process, the substrate 1 and the structured mold 2 are removed from their self-forming positions. Before removal, the substrate 1 is fixed back onto the substrate receiving device 6. The substrate 1 is fixed by vacuum or negative pressure via a vacuum track 9' of a vacuum device (not shown in the figure).

[0196] To remove from the molding position, use and activate (activation is indicated by arrows) all the fixing elements of the substrate receiving device 6, specifically, the fixing elements 9' that are individually controllable and uniformly distributed on the receiving surface.

[0197] Figure 1e The method demonstrates the imprinted and cured imprinted material 11 on substrate 1 after imprinting 1i. The method achieves high-resolution structuring in the sub-μm range, preferably less than 20μm, more preferably less than 2μm, more preferably less than 200nm, and most preferably less than 10nm.

[0198] Preferably, the device includes a group of modules that have a shared working space that requires visibility to be sealed relative to the surrounding atmosphere. The modules (e.g., coating modules, molding modules, unloading modules) may be arranged in a cluster or star shape around a central module that has a mobile device (robotic system).

[0199] Figure 3a This illustrates an embodiment of stamping substrate deformation due to capillary forces after contact between substrate 1', structured mold 2, and stamping material 7 located between them. (Source: [Original Source Name])Figure 3a The proportions of some components and substrate 1' are disproportionate, particularly tracing back to the structure 3 of the structured mold 2, which is represented in a magnified form. Due to capillary forces, the thin, flexible substrate 1' is attracted toward the structured mold 2 in a conformal manner. Because of the flexibility of substrate 1' and the degree of freedom gained from detaching it from the substrate receiving device 6, substrate 1' is deformable and adaptable to the structured mold 2. Therefore, uniform contact is achieved during imprinting. For this purpose, at least substrates 1 and 1' (preferably substrates 1 and 1' and the structured mold 2) must have a high degree of flexibility. Due to the high flexibility and conformal contact of substrates 1 and 1', imprinting defects are reduced or preferably eliminated.

[0200] Imprinting defects that can occur in prior art nanoimprinting include cracks, irregularly filled imprint structures (i.e., air inclusions), and uneven paint layer thickness. Adhesion between the imprinting material (e.g., paint) and the structured imprint is critical, because if, for example, the cured imprinting material 11' adheres more strongly to a recess in the structured imprint 2, twisting or cracking can occur, causing an imprint structure to tear during removal from its formed position. Irregularly filled imprint structures 3 result in defects in individual imprint structures within the cured imprinting material 11'. The filling of the imprint structure depends, in particular, on factors such as the viscosity of the imprinting material 7, the thickness of the coating, or the size, arrangement, and timing of the applied imprinting material droplets.

[0201] Specifically, further imprinting defects originate from defects in the structured mold 2 itself, such as (e.g.) a small depth or an uneven surface in some locations of the structure 3. Defects such as (e.g.) an uneven surface in the structured mold 2 are compensated for by the flexibility of the substrate 1.

[0202] According to the present invention, the soft-structured mold 2 will not deform during the process because no external pressure is applied. The substrates 1 and 1' are so thin that mold defects or defects that would have occurred in the prior art can be compensated for or even prevented from occurring. Figure 3b The imprinted and cured imprinted material 11′ is shown on the substrate li after it has been removed from the molding position.

[0203] Specifically, the proposed invention can be used to manufacture the following products:

[0204] - 1D, 2D and / or 3D diffractive optical elements (DOE),

[0205] - Microfluidic components

[0206] - Lenses and lens systems

[0207] - Fresnel lens,

[0208] -Biomedical components,

[0209] - polarizer,

[0210] - nanostructured electrode,

[0211] - IR waveguide,

[0212] - angular optics for virtual reality applications,

[0213] - fiber connection,

[0214] - working stamp for imprint lithography,

[0215] - and others.

[0216] Figures 4a to 4d Another embodiment in a step-and-repeat procedure is shown. A structured stamp 2' smaller than the substrate 1 " on which the structure is to be imprinted is used. According to Figures 4a to 4d the procedure is repeated as often as necessary or any number of times to imprint the entire substrate 1 " with the imprint material 7". The apparatus according to the present application can preferably be installed in a process chamber which is hermetically sealed against the ambient. Thus, the process chamber can be evacuated and / or ventilated with any gas or gas mixture.

[0217] Figure 4a A substrate 1 " with a layer of imprint material 7" over the entire area is shown. In another embodiment, droplets of the imprint material can be applied on the substrate 1 " at defined distances. The structured stamp 2' is smaller than the substrate 1 ". In particular, Figure 4a A cross-sectional view of a holding device 5' for holding a structured stamp 2' is also shown. The structure 3' of the structured stamp 2' has dimensions in the micrometer and / or nanometer range. In a preferred embodiment, the structured stamp 2' is fixed on the stamp holding device 5' by a vacuum or negative pressure via a vacuum track of a vacuum device (not shown in the figure).

[0218] In an advantageous embodiment of the present application, the device comprises a curing means for curing the imprinted substrate 1 " (in particular, section by section), the sections preferably corresponding to the step-and-repeat procedure, in particular, to a stamp area of the structured stamp.

[0219] The step-and-repeat device is considered a further development of the device described in patent specification EP 2 287 666 Al. In EP 2 287 666 Al, a step-and-repeat device for imprinting a substrate in a plurality of imprint steps within an imprint procedure and further devices contained in the device, in particular, an adjustment device, are described.

[0220] In accordance with Figure 4bIn a further process step of the step-and-repeat procedure, the step-and-repeat structured stamp 2' is structured from the imprint material 7". The structured stamp 2' is moved to a first position for imprinting in this first position. Preferably, only the structured stamp 2' is brought into proximity with respect to the static carrier substrate. After contact, direct cross-linking of the curable imprint material 7" (in particular a photoresist or a lacquer) is carried out by means of UV light 10. In general, the curing can be carried out by means of electromagnetic radiation, by means of heat, by means of an electric current, by means of a magnetic field or other methods. Preferably, the curing is carried out through the transparent stamp containment device 5' and the transparent structured stamp 2'. According to the application, it is also conceivable to cure the imprint material 7" by means of a radiation source in or on the stamp containment device 5'.

[0221] In accordance with the application, the structured stamp 2' is structured from the imprint material 7" in a step-and-repeat procedure. Figure 4c After removal from the forming position, a cured imprint material 11' is used to imprint the defined section of the substrate 1".

[0222] In accordance with the application, the structured stamp 2' is structured from the imprint material 7" in a step-and-repeat procedure. Figure 4d In a further process step of the step-and-repeat procedure, the step-and-repeat structured stamp 2' is moved from the first position to a second pre-defined position different from the first position and imprints again. After contact, direct cross-linking of the imprinted curable imprint material 7" is carried out by means of UV light 10. According to the application, it is also conceivable that a multiple curing is carried out, wherein a first curing is carried out locally after each individual imprinting step and, after completion of the step-and-repeat procedure, a further curing of the entire substrate 1" is carried out, for example, in a separate module.

[0223] In accordance with the application, the structured stamp 2' is structured from the imprint material 7" in a step-and-repeat procedure. Figures 4a to 4d The procedure can continue until the desired area of the imprinted substrate 1" has been imprinted. In this embodiment, the structured stamp 2' is capable of imprinting without external force after contact with the imprint material 7" on the substrate 1". The structured stamp has means for movement, in particular parallel to the substrate surface, and a lifting system for approaching in the Z direction and for removal from the forming position (not represented in the figures). The high precision of the positioning table of the step-and-repeat device enables seamless imprinting with the structured stamp 2' at the entire circumference of the substrate 1". According to the application, alignment with a previously imprinted structure (in particular, for example, an overlapping structure at the edge of a previously imprinted structure section) is possible. It is conceivable to use a continuous substrate in the step-and-repeat procedure. In particular, the continuous substrate is a substrate stored on a first roll, which is many times longer than it is wide. In particular, the continuous substrate is a film.

[0224] Imprinting by using the structured stamp 2' is carried out repeatedly or in parallel with each other to manufacture lens arrays, for example (in particular) micro-lens and / or nano-lens arrays.

[0225] According to the present application, no additional external pressure is required for successful imprinting. According to the present application, the stamp receiving device 5' is only brought close to the substrate 1" in a predefined position, so that the distance H is reduced to a precisely defined final distance H' E so that the stamping procedure is started without applying an additional external pressure. In particular, the final position H' E is smaller than 100 μm, preferably smaller than 10 μm, optimally smaller than 500 nm and most preferably smaller than 100 nm. By means of the action of the capillary forces, the thin flexible substrate 1" is attracted to the structured stamp 2' in a conformal manner. Due to the flexibility of the substrate 1", the substrate 1" can be deformed and adapted to the structured stamp 2'. Thus, a uniform contact during the imprinting is achieved.

[0226] LIST OF REFERENCE SIGNS

[0227] 1, 1', 1": substrate / product substrate

[0228] 1i: substrate after imprinting

[0229] 2, 2': structured stamp

[0230] 3, 3': imprinted structure

[0231] 4: stamp carrier substrate or back plate for stabilization

[0232] 5, 5': stamp receiving device

[0233] 6: substrate receiving device

[0234] 7, 7', 7": imprinting material

[0235] 8, 8': vacuum track in the stamp receiving device

[0236] 9, 9': vacuum track in the substrate receiving device

[0237] 10: radiation source

[0238] 11, 11': imprinted and cured imprinting material

[0239] 12: nozzle

[0240] 13: metering device

[0241] H: distance

[0242] H E , H' E : final distance.

Claims

1. A method for fabricating microstructures and / or nanostructures, comprising at least the following steps in sequence: a) Fixing a substrate (1, 1', 1'') having an imprinting material (7, 7', 7'') onto a substrate receiving device (6), b) Bring a structured mold (2, 2') into contact with the imprinting material (7, 7', 7''). c) At least partially remove the fixing of the substrate (1, 1', 1''), d) Curing the imprinting material (7, 7', 7''), f) Remove the imprinting material (7, 7', 7'') from the structured impression (2, 2'). After at least partially removing the fixation of the substrate, at least part of the substrate (1, 1', 1'') is detached from the substrate receiving device (6) by means of relative movement between the substrate receiving device (6) and the substrate (1, 1', 1'') and / or by means of relative movement between the substrate receiving device (6) and a mold receiving device (5, 5') and / or by means of capillary force. The embossed material (7, 7', 7'') is structured under no pressure and / or no contact pressure. The substrate (1, 1', 1'') having the imprinting material (7, 7', 7'') is fixed to the substrate receiving device (6) by at least one controllable fixing element (9, 9') disposed in the substrate receiving device (6), and / or the fixing is canceled by the at least one controllable fixing element (9, 9'). The fixing of the substrate (1, 1', 1'') and at least partial cancellation of the fixing of the substrate (1, 1', 1'') are controlled by controlling at least one controllable fixing element (9, 9'), so that the structuring of the imprint material (7, 7', 7'') and / or the release or removal of the substrate (1, 1', 1'') after the structured mold (2, 2') comes into contact with the imprint material (7, 7', 7'') are performed at a specific time. The substrate (1, 1', 1'') is flexible and thus fits into the structured mold (2, 2') in a form that is at least partially conformal after the fixation is at least partially removed.

2. The method according to claim 1, wherein the structured mold (2, 2') is constructed such that after at least partially removing the fixation, the imprinting material (7, 7', 7'') and / or the substrate (1, 1', 1'') are conformally adapted to the structured mold (2, 2') without external pressure.

3. The method according to claim 1 or 2, wherein the substrate (1, 1', 1'') is held in place by the imprinting material (7, 7', 7'') after the contact and / or after at least partially releasing the fixation.

4. The method according to claim 1 or 2, wherein the microstructure and / or nanostructure is fabricated one on top of the other in multiple layers and / or side by side in a step-by-step repeating process.

5. The method according to claim 1 or 2, wherein the thickness of one of the substrates (1, 1', 1'') is between 1 µm and 2000 µm.

6. The method according to claim 1 or 2, wherein the thickness of one of the substrates (1, 1', 1'') is between 10 µm and 750 µm.

7. The method according to claim 1 or 2, wherein the thickness of one of the substrates (1, 1', 1'') is between 100 µm and 500 µm.

8. The method according to claim 1 or 2, wherein the structured impression (2, 2') comprises an impression structure (3, 3') and / or an impression structure (3, 3') is coated.

9. An apparatus for fabricating microstructures and / or nanostructures, fabricated using the method according to claim 1, wherein... A substrate (1, 1', 1'') having an imprinting material (7, 7', 7'') can be fixed on a substrate receiving device (6), and wherein A structured mold (2, 2') can contact the imprinting material (7, 7', 7''), and wherein... The fixing of the substrate (1, 1', 1'') can be at least partially removed, and wherein The imprinting material (7, 7', 7'') can be cured, and in it The embossing material (7, 7', 7'') can be demolded from the structured mold (2, 2').

10. The apparatus of claim 9, comprising: One or more sensors for measuring pressure, distance and / or temperature, and / or One or more actuators for adjusting the impression receiving device (5, 5') and / or the substrate receiving device (6), and One control unit, The control unit controls the at least one fixed element (9, 9') and / or the at least one actuator, wherein the structured mold (2, 2') can be moved relative to one of the substrates (1, 1', 1'') having the imprinting material (7, 7', 7'') so that contact can be made.

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