WO2021001242A1

WO2021001242A1 - Method for producing a molding tool and molding tool for producing an optical element

Info

Publication number: WO2021001242A1
Application number: PCT/EP2020/067703
Authority: WO
Inventors: Marcel Röder; Thomas Günther; André Zimmermann; Harald Giessen; Mario Hentschel; Simon Thiele
Original assignee: Hahn-Schickard-Gesellschaft für angewandte Forschung e.V.
Priority date: 2019-07-02
Filing date: 2020-06-24
Publication date: 2021-01-07
Also published as: DE102019209700A1

Abstract

The invention relates to a method (100) for producing a molding tool (20). The method (100) includes the provision of a workpiece which has a workpiece surface (22) comprising a metal. The method (100) further includes a structuring of the workpiece surface (22) by at least partially removing the metal from the workpiece surface (22) using an ion beam, thus resulting in a microstructured or nanostructured workpiece surface which forms a structured molding tool surface (24). According to the invention, the structuring of the workpiece surface (22) is carried out at least in some sections with a depth resolution in the submicrometer range of less than 1 μm and/or with a lateral resolution in the submicrometer range of less than 1 μm.

Description

METHOD OF MANUFACTURING A MOLDING TOOL AND

MOLDING TOOL FOR MANUFACTURING AN OPTICAL ELEMENT

description

The invention relates to a method for producing a molding tool, for example a stamp for producing impressions. The invention also relates to a molding tool produced using such a method. The invention also relates to a molding tool for producing an optical element, for example a stamp for producing impressions for optical elements.

The invention is in the technical field of the manufacture of articles and products by means of shaping processes. Suitable molding tools are used for this, which can be used, for example, as negative molds or positive molds for molding a product to be finally manufactured. These molding tools can be used as interchangeable tool inserts in larger machines for the mechanical production of a wide variety of products.

For example, hot stamping processes, injection molding processes and molding processes are known in which such a molding tool can be used. For example, plastic or polymers are applied to the molding tool, and the plastic is then deformed under pressure and / or heat and then detached from the molding tool. It is therefore desirable, inter alia, that such a molding tool has good thermal conductivity and offers good demouldability. Metals are very suitable for this. Nowadays it is known to manufacture metal molds by means of machining processes. In this case, the molding tools are produced, for example, by means of a milling machine, in that a metallic workpiece blank is processed on the surface with the milling machine such that the finished workpiece surface ultimately forms a structured molding tool surface. Tool steels are often used as the starting material for this, since the molding tool made from tool steel has a long service life, ie it can be used several hundred thousand to million times for molding, These machining processes are particularly suitable for molding tools with large dimensions. However, smaller molding surfaces or molding tool surfaces can also be produced, for example, by means of precision milling, in which case an accuracy of down to a few micrometers can be achieved. Nowadays, for example in the electronics sector, the miniaturization of products is playing an increasingly important role. There is an increasing demand for products with small structure sizes that should be manufactured with the highest possible precision. This means that products are required whose surfaces are manufactured with such an accuracy that their structural resolution is in the submicrometer to nanometer range. One example of this are so-called microlenses, which are used in smartphones and other consumer electronics devices. The surfaces of these microlenses must be produced extremely precisely, ie with a structural resolution in the submicrometer or nanometer range, so that the finished molded lens has a surface that is as precisely formed as possible, for example smooth. This is the only way to ensure that such miniaturized lenses also fulfill their desired function.

For the production of such molding tools, which have a precision in the submicrometer or nanometer range for molding miniaturized products, different methods are known in the field of so-called ultra-precision machining. For example, molding tools for the precise molding of miniaturized products can be produced by means of gray-scale lithography, for example by means of photo or electron beam lithography, by etching step structures in silicon or other materials, which are then molded with nickel shims, e.g. using electroplating. The molding tools can then be used for molding, for example for embossing, pressing, casting or molding with a nanoimprint lithography method, in particular for hot stamping, injection molding, transfer molding or injection molding.

As mentioned at the beginning, metals are very suitable for this because they have good thermal conductivity. In order to achieve the longest possible service life for the molding tool, hard metals are preferred for manufacturing the molding tool. Nickel has a Mohs hardness of 4 and is currently the hardest metal that can be processed into a mold using the above-mentioned precision processes (including electroplating). However, compared to tool steels, the Mohs hardnesses are in the range from 6 to 8.5, still significantly less, which means that the service lives of molds made of nickel are significantly reduced compared to molds made of tool steel. Applied to the example described above, this means that nickel can be machined very precisely, but that the nickel shims do not allow tool lives that allow millions of impressions. They usually have to be replaced after several 10,000, at best up to a few 100,000 impressions, since the accuracy of the impression decreases and they gradually wear out during the impression process.

Attempts have been made in the professional world to counteract this deficiency by producing molds from dielectrics or semiconductor materials such as silicon. The advantage here is that such materials are extremely hard. For example, silicon has a Mohs hardness of 6.5 and is therefore in the range of tool steels. A major disadvantage, however, is that dielectrics or semiconductor materials are also very brittle at the same time and have poor toughness. In practice, this has resulted in molds made with such materials breaking in use. Apart from that, such materials have a significantly poorer thermal conductivity compared to e.g. tool steels or other metals, which makes them particularly unsuitable for use in hot stamping processes. There is therefore a conflict of objectives insofar as molding tools are required for the production of miniaturized products that have extremely high precision, i.e. very precise structural resolution in the submicrometer or nanometer range, and which at the same time have a very long service life.

The inventors have succeeded in using the method according to claim 1 to produce a molding tool that combines the properties mentioned above and previously considered incompatible. The method enables hard metals, which allow a long service life, to be machined directly, with such precision that structures in the mold surface in the submicrometer or nanometer range can be produced. Not only can simple trench structures, steps or holes be created, but rather there is a great advantage that, due to the direct precision machining of the metal, any free shapes can actually be produced. Technologies currently used are not able to structure such materials directly and maintain the required levels of accuracy. The invention thus solves the problems of the prior art mentioned at the beginning with a method for producing a molding tool according to claim 1, a molding tool produced according to this method according to claim 14 and a molding tool which can be produced with this method for producing an optical element having the features according to claim 15. Conceivable embodiments and further advantageous aspects of the invention are mentioned in the respective dependent claims.

In the method according to the invention for producing a molding tool, a workpiece is first provided which has a workpiece surface comprising a metal. The workpiece is, so to speak, the starting object from which the molding tool is made. The workpiece can consist of metal or, at least in sections, have a metal. The workpiece can advantageously have a metal on at least one easily accessible workpiece surface. The method further includes structuring the workpiece surface by at least partially removing the metal from the workpiece surface by means of an ion beam, so that a micro- or nanostructured workpiece surface is created which forms a structured mold surface. The workpiece surface containing the metal can be processed extremely precisely by means of the ion beam. The metal on the workpiece surface can be structured as desired (ie as a free form) by means of the ion beam, whereby the ion beam enables the finest layers of metal to be removed and even individual atoms to be knocked out of the metallic structure. By structuring or removing the metal, the finished structured mold surface is gradually created from the workpiece surface. In the method according to the invention, the structuring can preferably be carried out with a depth resolution in the submicrometer range of less than 1 mm and / or with a lateral resolution in the submicrometer range of less than 1 mm. In this case, the depth resolution can, for example, indicate a maximum deviation that can be realized with the ion beam from a target value for the removal of the metal in the depth direction. The depth denotes a distance along the depth direction, in particular starting from the workpiece surface. The depth direction can be a direction running essentially perpendicular to the surface to be structured of the workpiece or of the tool body. Equally meaning, the depth direction can be dimensioned starting from the workpiece surface in the direction of a further workpiece surface, wherein the workpiece surface is preferably arranged opposite the further workpiece surface. The depth direction can be perpendicular to any lateral direction be. A direction can be said to be lateral if it is substantially parallel to the workpiece surface. A lateral direction can also be referred to as a lateral direction. The lateral resolution can designate the lateral dimension of the smallest removal of the metal that can be realized with the ion beam. According to one exemplary embodiment, the structuring can be carried out at least in sections with a depth resolution of less than 500 nm, or of less than 100 nm, or of less than 10 nm. By structuring the workpiece surface with this particularly good depth resolution, molding tools with metallic molding surfaces can be produced which cannot be produced using other methods, not even using ultra-precision machining or laser direct writing techniques. For example, molding tools produced by the method according to the invention are very well suited for the production of optical elements. Due to the specified depth resolution, the method according to the invention is very universally replaceable for the production of a large number of very different products, such as, for example, optical elements to be manufactured with the highest precision and in particular polymer optical elements.

According to one embodiment, the structuring can be carried out at least in sections with a lateral resolution of less than 500 nm, or of less than 100 nm, or of less than 10 nm. For example, the structuring with this lateral resolution can be carried out in a metal with a microstructure that is finer than the lateral resolution. Structuring with the specified lateral resolution is advantageous, for example, in order to produce particularly small-structured mold surfaces with the highest precision, which are suitable, for example, for the production of particularly fine and extremely precise product surfaces. Particularly in combination with the specified depth resolution, extremely smooth surfaces and slopes can be produced. In particular, molding tools can be produced whose structured molding tool surface can have better structural resolution, smoother surfaces and bevels and smaller radii than molding tools which have been produced using conventional methods for machining metals, for example using cutting methods or using ultra-precision machining. According to an exemplary embodiment, the metal can have a Mohs hardness of greater than 4. This means that the metal to be structured is harder than nickel, which is currently the hardest metal that can nowadays be processed using known methods (eg galvanic deposition) to produce molds. The metal to be structured on the workpiece surface can also be a metal which is usually can not be galvanically deposited. The production of a mold with particularly small structures is usually based on electrodeposition. Usually, nickel and nickel compounds are considered to be the hardest electrodepositable metals. The method according to the invention uses the direct processing of metals with an ion beam and makes the intermediate step of galvanic deposition of a metal on a stamp, for example a multi-stage stamp, superfluous. The method according to the invention thus opens up the possibility of producing molds from any metals, in particular metals that are harder than nickel, and for example from metals that have a Mohs hardness of greater than 4. Forming tools made of such particularly hard metals are particularly advantageous with regard to long service lives and high dimensional accuracy. Technologies currently used are not able to structure such metals directly and thereby achieve the high accuracies of the method according to the invention.

According to one embodiment, the metal can be titanium, or a metal at least as hard as titanium, for example tungsten, chromium or molybdenum. In general, metals are preferred as the material for a molding tool. On the one hand, these can be ferrous metals, which are magnetic, which limits their application to processing without immersion mode. Furthermore, experiments with ferrous metals give poor results even without the immersion mode due to the very inhomogeneous microstructure. This actually includes all tool steels. Then there are the typical non-ferrous metals such as copper, nickel, nickel-phosphorus, aluminum, etc. These typically do not have sufficient hardness. Titanium as a material for the workpiece offers the advantage that it has a sufficiently fine structure to be structured in the nanometer range. For example, titanium has a finer microstructure than conventional tool steels. Titanium is very hard, which means that a long service life and high dimensional accuracy can be achieved. In addition, titanium is sufficiently tough not to break when used as a molding tool. In addition, titanium is not magnetic, which means that an immersion mode can optionally be used for machining with an ion beam. As a bulk material, titanium can be machined as a large block, which means that entire punches can be manufactured in one part. On the other hand, the material does not break as easily as crystalline materials such as silicon or ceramics. Titanium has a sufficiently suitable coefficient of thermal expansion, is hard enough for wear protection, and has a sufficiently fine structure to be structured cleanly in the submicrometer and nanometer range. Titanium is also relatively cheap, for example compared to tungsten. Titanium is hard, tough and low-wear. Usually titanium is difficult to machine because the machining tools wear out very quickly. In the method according to the invention, which structures titanium with the aid of ion beam lithography, such wear no longer occurs.

According to one embodiment, the ion beam can have ions of at least one of the materials gold, silicon, carbon, platinum, gallium. For example, Au +, Au ++, Si +, and Si ++ ions can be used. Such an ion beam is particularly well suited for the removal of metals, in particular for the removal of hard metals, in particular for the removal of titanium, with good suitability due to a high removal rate and high accuracy, in particular good depth resolution and good lateral resolution of the structuring indicates. Alternatively, the ion beam can also have other ions which are particularly suitable for removing metals, in particular for removing hard metals, in particular for removing titanium. The combination of the use of a titanium stamp and its micro- and nano-structuring with the aid of Au / Si ion beams and the subsequent molding in a liquid / viscous polymer, liquid glass or other materials can be advantageous here.

According to one embodiment, the structured molding tool surface can have a maximum depth of 0 mm to 100 mm, or from 0 mm to 10 mm, or from 0 mm to 2 mm. Compared to molds with deeper, structured mold surfaces, this has the advantage that the molds can be removed from the mold better. This can be the case in particular for molding tools with a particularly finely structured molding tool surface. The structured mold surface can, for example, have a maximum depth corresponding to the wavelength of the light which is compatible with the optical element to be produced. The structured mold surface can, however, also have a maximum depth greater than the wavelength of the light that is compatible with the optical element to be produced, for example if the optical element to be produced is a reflective element.

According to one embodiment, the structured mold surface can have a lateral area in the range between 400 nm ² and 35,200 mm ² or between 400 nm ² and 10,000 mm ² . On the one hand, this offers the advantage that small areas can be structured in a targeted and selective manner, which can reduce the duration of the structuring and thus increase profitability. On the other hand, very large areas can also be structured, for example 8 inch wafers or 4 inch wafers, which can be particularly advantageous in the mass production of optical elements. The structured mold surface can in particular be very much larger than the dimensions of a structure produced, for example a molding structure. In other words, the structuring can be carried out over a large area compared to the structure size, ie up to a few square millimeters. Furthermore, the structured molding tool surface can be larger than a single writing field of the system for structuring by means of an ion beam, in particular the structured molding tool surface can be created by a large number of such fields by means of so-called “stitching”. This enables the nano-direct machining of larger workpieces, for example tool components. Whereas in the past individual structures were manufactured on small elements, larger workpieces, for example tool blocks, can now be structured directly. The advantages are that, firstly, no molds are required, which improves hardness and service life and avoids alignment of the nanostructures in the overall tool, and secondly, no joints are required between different tool components, which means that the nanostructures in the tool are not aligned and as a result of which reliability problems in thermal replication processes can be avoided, and thirdly, special layers for nanostructuring are no longer necessary, as a result of which additional costs for coatings and delamination in thermal processes can be avoided. Furthermore, a dimension of a structure, for example a dimension of a molding structure, in at least one lateral direction can be just as large as or smaller than the dimension of the structured mold surface in this lateral direction.

According to one embodiment, the structuring of the workpiece by means of the ion beam can be carried out in such a way that the structured molding tool surface has a free form that can be produced subtractively from one direction. This offers the advantage of great flexibility in the design of a product to be manufactured using the molding tool, for example an optical element. A special feature of the process is that any structure and shape can be produced. These include, on the one hand, rotationally symmetrical or non-rotationally symmetrical shapes, which otherwise cannot be produced using other methods, e.g. ultra-precision machining or laser direct writing techniques, and, on the other hand, freeform surfaces, i.e. structures of any shape, provided that they can be subtractively produced from one beam direction. Examples of this are optical elements such as phase plates, wavefront corrections or digital diffractive patterns. This fact makes the method according to the invention very universally applicable for the production of a large number of different products, and in particular highly precise optical elements, and therefore represents a key technology in particular in the manufacture of polymer optical elements. The free form can be, for example, a shape that was designed in a digital model, for example in a CAD model, or was calculated by means of a simulation.

According to one embodiment, the structuring of the workpiece by means of the ion beam can be carried out in such a way that the structured molding tool surface forms a negative form or a positive form for a product which can be produced with the molding tool to be produced. A negative mold is, for example, a mold from which a product surface of the product can be produced by a one-off molding. A positive form is, for example, a form from which a negative form can be produced by means of a one-time impression. In particular, the positive mold can have the same shape as the product surface to be produced. The use of positive molds is advantageous, for example, if the shape of the product to be manufactured requires a large-area removal of the “non-shape”, or if the mold to be manufactured can only be manufactured as a positive. The exemplary embodiment has the advantage that the negative forms or positive forms can be designed in advance as a digital model and can be produced with great accuracy directly in the workpiece as a molding tool using the method according to the invention.

According to an embodiment, the product can be an optical element, for example a phase plate, a wavefront correction or a diffractive pattern, in particular a digital diffractive pattern. In particular, the optical element can have been designed in a digital model, for example a CAD model; in particular, the digital model can also be the result of a simulation, for example a wavefront calculation or a calculation for warpage and shrinkage. The method according to the invention is particularly advantageous for the production of molds for optical elements, because the accuracy required for this is not achieved by other methods, in particular not by methods that are able to structure hard metals directly. In addition, in the production of optical elements it is particularly advantageous to be able to produce free forms with good lateral resolution and good depth resolution. Optical elements require a high accuracy of the surface of the molding tool, which can be ensured by the method according to the invention in that a metal, for example a hard metal with a fine microstructure, is structured with the specified depth resolution and with the specified lateral resolution. In addition, optical elements are produced in large numbers. Therefore, a long life of the mold, such as it can be provided with the method according to the invention, be advantageous for the economy of production.

According to one embodiment, the product can be a refractive optical element or a diffractive optical element or a reflective optical element. For example, the product can be an optical lens, in particular an optical microlens, a mirror element, a grating, a filter, a beam shaper, a beam splitter, a Gaussian generator, a phase plate, a wavefront correction element or a diffractive pattern element or an element that has several these elements combined.

According to one embodiment, the product can be a diffractive lens or a Fresnel lens or a Fresnel-like diffractive lens. In particular, the lens can have been calculated using a simulation, for example using a model for optical design or a model for calculating diffractive patterns or wavefronts. For optical lenses in particular, it is particularly advantageous to be able to transfer the digital model directly to the molding tool. The invention further comprises a molding tool that can be produced directly using the method described herein.

The invention further comprises a molding tool for producing an optical element, wherein the molding tool has a structured molding tool surface comprising a metal, the metal having a Mohs hardness of greater than 4, and wherein the structured molding tool surface has at least one molding structure with a dimension im Sub-micrometer range of less than 1 mm and / or with a dimension in a depth direction in the sub-micrometer range of less than 1 mm. A molding structure can be understood to be a structural or geometric element of the structured molding tool surface, which serves to produce a corresponding counter-structure on the product to be manufactured. The molding structure can be, for example, a preferably three-dimensional elevation or depression in the molding tool surface. For example, it would be conceivable for the molding tool surface to have a comb structure, one prong of the comb corresponding in each case to an impression structure. The structured molding tool surface can accordingly also have a large number of molding structures. At least the lateral extension (for example length and / or width) of an impression structure can be smaller than 1 mm. Alternatively or additionally, the impression structure can have a dimension in the depth direction (eg height or depth) of less than 1 mm. In other words, despite the hard metal, the structured molding tool surface is structured so precisely that the molding tool surface has one or more molding structures that can be smaller than 1 mm. This is made possible by producing the molding tool using the method according to the invention described herein. The molding tool according to the invention thus offers the advantage over previously known molding tools that it has a molding tool surface structured in the submicrometer range and at the same time consists of a hard metal, ie it is hard enough for wear protection and has a sufficiently fine structure to be clean in the submicrometer range to be structured down to the nanometer range. In addition, the molding tool also has all the properties and advantages described herein with reference to the method according to the invention.

According to one exemplary embodiment, the molding tool can have a melting point which is above the melting point or the glass transition temperature of polymers and / or glass. This offers the advantage that the molding tool can be used in a molding process in which the molding tool is to be molded with a liquid glass or a liquid polymer.

According to one embodiment, the molding tool can be designed to be used as an insert in a device for molding, for example embossing, pressing, casting or molding with a nanoimprint lithography method, in particular for hot stamping, injection molding, transfer molding or injection molding, of the optical element from a Polymer or a glass. The shaping of the optical element can also include producing an intermediate shape and producing the optical element from an intermediate shape.

Further exemplary embodiments of the molding tool result from the exemplary embodiments of the method for producing a molding tool, the method features being transferable analogously to the device features, which also applies the other way round.

Some exemplary embodiments are shown by way of example in the drawing and are explained below. 1 shows a block diagram of a method according to the invention for producing a molding tool according to an exemplary embodiment, 2 (a) shows a side sectional view of a molding tool according to the invention for producing an optical element according to an exemplary embodiment,

FIG. 2 (b) shows an enlarged detail from FIG. 2 (a),

3 shows a plan view of a molding tool according to the invention for producing an optical element according to a further exemplary embodiment,

4 (a, c) a plan view of a structured molding tool surface according to two further exemplary embodiments,

4 (b, d) two-dimensional height and depth profiles of the structured molding tool surfaces shown in FIGS. 4 (a, c), FIG. 5 (a, b) a plan view of a structured molding tool surface according to a further embodiment ,

FIG. 5 (c) shows a three-dimensional height or depth profile of the structured molding tool surface shown in FIGS. 5 (a, b),

5 (d) a two-dimensional height or depth profile of the structured molding tool surface shown in FIGS. 5 (a, b),

5 (e) shows an enlarged section from the two-dimensional height and depth profile shown in FIG. 5 (d) of an exemplarily selected impression structure,

6 (a, c) a plan view of an impression produced by means of the structured molding tool surface shown in FIGS. 4 (a) and 4 (c),

6 (b, d) two-dimensional height and depth profiles of the impressions shown in FIGS. 6 (a) and 6 (c),

FIG. 7 (a) shows a plan view of an impression of the structured one shown in FIG. 5 (a)

Mold surface, Fig. 7 (b) shows a three-dimensional height and depth profile of the one shown in Fig. 7 (a)

Impression taking, and

Fig. 7 (c) shows a two-dimensional height and depth profile of the one shown in Fig. 7 (a)

Impression. In the following, exemplary embodiments are described in more detail with reference to the figures, elements with the same or similar function being provided with the same reference symbols. Method steps that are shown in a block diagram and explained with reference to the same can also be carried out in a sequence other than that shown or described. In addition, method steps that relate to a specific feature of a device are interchangeable with this same feature of the device, which also applies the other way around. FIG. 1 shows a block diagram of a method 100 according to the invention for producing a molding tool 20 (see, inter alia, FIG. 2) according to an exemplary embodiment.

The method 100 comprises a first step 101 in which a workpiece is provided that has a workpiece surface comprising a metal. The workpiece can be designed to form a tool body. The workpiece or the workpiece surface can have structures produced using other methods. The workpiece can be designed to be able to be integrated into a tool or to be able to be used with a tool.

In step 102, the workpiece surface is structured by at least partially removing material, in particular the metal, from the workpiece surface by means of an ion beam, so that a micro- or nano-structured workpiece surface is created, which forms a structured molding tool surface 24 (see FIG. 2) , the structuring being carried out at least partially in the submicrometer range of less than 1 mm and with a lateral resolution in the submicrometer range of less than 1 mm.

The depth resolution indicates a maximum deviation that can be achieved with the ion beam from a target value in the depth direction for the removal of the metal. The depth direction is the direction perpendicular to the workpiece surface. The depth direction shows the same meaning starting from the workpiece surface in the direction of a second surface of the workpiece opposite the workpiece surface. The depth direction is perpendicular to any lateral direction. A direction can be said to be lateral if it is parallel to the workpiece surface.

The lateral resolution is a lateral dimension of the smallest depression that can be realized with the ion beam by removing the metal and is at least 10 nm deep. The structuring 102 by means of the ion beam can be carried out with an ion beam writer with a focused ion beam (FIB, “focused ion beam”). Ions, for example gold ions (Au + / Au ++), which have been accelerated with a voltage of 35 kV, for example, can be focused on a substrate surface, for example on the workpiece surface.

The structuring 102 can include guiding an ion beam over the substrate, for example the workpiece surface, for example with a step size of 40 nm, in order to remove material. As a result, structure sizes, for example dimensions of impression structures, of less than 100 nm can be generated. The ion beam writer can have an ion source, an electrostatic lens, an electrostatic deflection electrode or a diaphragm. The structuring 101 can be carried out over a large area, even on an area which is larger than the area of a writing field of the ion beam writer. The workpiece can be moved relative to the ion beam. The writing fields can be joined to one another in such a way that individual structures, for example impression structures, can also be written which have a lateral dimension larger than the size of a writing field of the ion beam writer (“stitching”).

FIG. 2A shows a side sectional view of a molding tool 20 according to the invention which can be produced with the method 100 according to the invention according to a non-limiting embodiment. The molding tool 20 can be used, for example, to produce an optical element. FIG. 2B shows an enlargement of a detail from FIG. 2A.

FIGS. 2A and 2B show a molding tool 20 which is produced from a workpiece and has a workpiece surface 22 comprising a metal. The workpiece surface 22 can be structured by means of the method 100 according to the invention, so that a structured molding tool surface 24 is created.

The metal to be structured on the workpiece surface 22 can have a Mohs hardness of greater than 4. It can be titanium, for example, or hard tool steels such as chromium, molybdenum, vanadium and the like.

The structured mold surface 24 is used in the manufacture of products, such as optical elements, for molding the respective product. Therefor the mold surface 24 essentially has a copy (as a positive or a negative) of the desired surface of the product to be manufactured. In order to ensure the most precise possible surface structure of the product to be manufactured, the molding tool surface 24 should therefore also be manufactured or structured with at least as high a precision.

The molding tool surface 24 has at least one molding structure 27. The molding structure 27 is preferably a three-dimensional structure which can have different geometric shapes. After the product (e.g. microlens) has been manufactured, the finished product 61 (see FIGS. 6 and 7) has a shaped structure 21, 121 (FIGS. 6 and 7) congruent to the impression structure 27 on its surface. This can be, for example, a corner, edge, step, rounding and the like. As is shown by way of example in FIGS. 2A and 2B, the molding tool surface 24 can also have a multiplicity of molding structures 27.

According to the invention, the at least one molding structure 27 has a dimension in a lateral direction 28 in the submicrometer range of less than 1 mm. The lateral

Direction 28 relates in particular to the molding tool surface 24 or to the (unstructured) workpiece surface 22 and is essentially parallel thereto. Alternatively or additionally, the at least one molding structure 27 has a dimension in a depth direction 29 in the submicrometer range of less than 1 mm. The depth direction 29 relates in particular to the molding tool surface 24 or to the (unstructured) workpiece surface 22 and is essentially perpendicular to it.

The structured molding tool surface 24 can have a lateral surface section which can be defined by one or more lateral dimensions 25. An unstructured workpiece surface 22 ′ corresponds to the workpiece surface from which the structured molding tool surface 24 was created by the structuring 102 according to the invention.

This structured molding tool surface 24 can have a structure depth 26 which defines a maximum distance between the structured molding tool surface 24 and the unstructured workpiece surface 22 ′, in the depth direction 29. According to conceivable embodiments, the structured molding tool surface 24 can have a maximum structure depth 26 of 0 mm to 100 mm, or from 0 mm to 10 mm, or from 0 mm to 2 mm. FIG. 2B shows an enlarged section of the exemplary structured molding tool surface 24 from FIG. 2A with a large number of different molding structures 27. An molding structure 27 can, for example, have an elevation 27A, which is delimited from adjacent molding structures 27 by a further elevation 27A or a depression 27B can be. As an alternative or in addition to an elevation 27A, an impression structure 27 can also have, for example, a depression 27B, which in turn can be delimited from adjacent impression structures 27 by an elevation 27A or a further depression 27B.

An impression structure 27 can have any geometric structure (free form) which can have a flank 21, for example a continuous flank, and / or a step 23.

As mentioned above, an impression structure 27 can have a dimension in the lateral direction 28 and a dimension in the depth direction 29. A dimension in the depth direction 29 can correspond, for example, to the height of at least one section of an impression structure 27 configured as an elevation 27A. A dimension in the depth direction 29 can correspond, for example, to the depth of at least one section of an impression structure 27 configured as a depression 27B.

In the non-limiting exemplary embodiment shown here, a dimension in the depth direction 29 can therefore correspond, for example, to a step height 29A of a step 23 or a maximum height 29B of an impression structure 27 configured as an elevation 27A. The maximum height 29B can be, for example, a maximum elevation in the molding tool surface 24 or a maximum elevation of the molding structure 27A relative to a depression 27B delimiting the molding structure 27A.

A dimension in the depth direction 29 can also be, for example, a maximum depth 29C of an impression structure 27 configured as a depression 27B, the maximum depth 29C of a maximum depth of the impression structure 27 configured as a depression 27B relative to an elevation 27A delimiting the impression structure 27B.

A dimension in the depth direction 29 can also be the roughness of a flank 21, for example. In general, the dimension in the depth direction 29 can describe a (shortest) distance between a lowest point 31 and a highest point 32 of the respective impression structure 27. Such a dimension of a molding structure 27 in the depth direction 29 can, according to the invention, be less than 1 mm, preferably less than 500 nm, more preferably less than 100 nm and even less than 10 nm. The most precise generation of this kind Small mold structures 27 in a hard metallic mold surface 24 is made possible with the method 100 according to the invention.

According to the invention, the molding structures 27 can also be manufactured with the utmost precision in the lateral direction. In general, the dimension in the lateral direction 28 can describe a (shortest) distance between two laterally (maximally far) spaced apart points 33, 34 of the respective impression structure 27. According to the invention, such a dimension of a molding structure 27 in the lateral direction 28 can be smaller than 1 mm, preferably smaller than 500 nm, more preferably smaller than 100 nm and even smaller than 10 nm.

A dimension in the lateral direction 28 can be, for example, a step width 28A of an impression structure 27 configured as a step 23, or an average width 28B of an impression structure 27 configured as an elevation 27A. The average width can be, for example, an averaged lateral dimension of an impression structure 27, wherein the average value can be formed over a maximum height 29B (an elevation 27B) or over a maximum depth 29C (a depression 27A). A molding structure 27 can have an aspect ratio of, for example, 2: 1 or 3: 1, i.e. a ratio between a dimension in the depth direction 29 and a dimension in the lateral direction 28 can be, for example, less than 3 or 2. Establishing higher aspect ratios can be technically demanding.

In other words, the dimension of the molding structure 27 in the lateral direction 28 can describe the length and / or the width of the molding structure 27, and the dimension in the depth direction 29 can describe the depth or height of the molding structure 27. This is explained in greater detail below with reference to FIGS. 4 and 5. As a result, using the method 100 according to the invention, at least one molding structure 27 can be produced in the molding tool surface 24, which is smaller than 1 mm, preferably smaller than 500 nm, more preferably smaller in each direction (ie length, width, depth / height) than 100 nm and even smaller than 10 nm. One advantage of the method 100 according to the invention is, among other things, that one is not restricted to certain geometric shapes (e.g. trench structures or concentric shapes), i.e. the at least one molding structure 27 can be produced as any free shape.

FIG. 3 shows a top view of a non-limiting example of a molding tool 20 according to the invention for producing an optical element according to an embodiment example. A molding tool surface 24 with a large number of different molding structures 27 is shown here as an example.

For example, an impression structure 27 is shown which extends transversely over the molding tool surface 24 and which can start out as an elevation 27A or a depression 27B. A dimension in the lateral direction 28 of this molding structure 27 can be just as large as or smaller than the dimension 25 of the structured molding tool surface 24 in this same lateral direction. That is to say, the molding structure 27 can extend over the entire molding tool surface 24 or just over only part of the molding tool surface 24. Furthermore, a dimension in the lateral direction 28 of this molding structure 27 can be larger than an individual writing field 30 of the ion writer used in the method 100.

The lateral surface area of the structured mold surface 24 may range between 400 nm ² and 35,200 mm ^2, or between 400 nm ² and 10,000 mm ² Lie gene. However, the lateral surface area may also be greater.

Figures 4 (a) and 4 (c) each show a plan view of a structured mold surface 24 according to two non-limiting exemplary embodiments. The structured molding tool surfaces 24 shown each have a large number of different molding structures 27. The molding structures 27 are formed according to the invention by subtractively produced free forms.

Each molding structure 27 has a dimension in the lateral direction 28. As mentioned at the beginning, this can be the length 28L or the width 28B of the molding structure 27. With the method 100 according to the invention, the molding tool surface 24 can be structured so precisely that at least one of the generated or structured impression structures 27 has a lateral dimension 28L, 28B (e.g. length and / or width) that is smaller than 1 mm, preferably can be smaller than 500 nm, more preferably smaller than 100 nm and even smaller than 10 nm.

Alternatively or additionally, the molding tool surface 24 can be structured so precisely that at least one of the generated or structured molding structures 27 has a dimension in the depth direction 29 (eg depth) that is less than 1 mm, preferably less than 500 nm, more preferably can be smaller than 100 nm and even smaller than 10 nm. Figures 4 (b) and 4 (d) show two-dimensional height and depth profiles 41 of the structured molding tool surfaces 24 shown in FIGS. 4 (a) and 4 (c). The respective depth 29 of the molding structures 27 can be determined from the profiles 41.

As can also be seen in FIGS. 4 (a) and 4 (c), the entire structured mold surface 24 also has dimensions in the lateral direction, for example a length 25L and a width 25B of the Form tool surface 24 can act. The product of length 25L and width 25B gives the above-mentioned lateral area or areal extension of the mold surface

24. FIGS. 5 (a) and 5 (b) each show a plan view of a structured molding tool surface 24 according to a further conceivable exemplary embodiment. In this non-limiting exemplary embodiment, the molding tool produced by means of the method 100 according to the invention can be used to produce a Fresnel-like diffractive lens. The structured molding tool surface 24 here again has lateral dimensions 25. In this example, the molding structures 27 are elevations or depressions arranged in a rotationally symmetrical manner. Accordingly, the lateral dimensions 25 of the molding tool surface 24 can be, for example, a radius of the molding tool surface 24. FIG. 5 (c) shows a three-dimensional profile of the structured molding tool surface 24 shown in FIGS. 5 (a) and 5 (b). It should again be explicitly pointed out at this point that the molding tool surface 24 or the molding structures 27 is not restricted to the concentric arrangement shown as an example. Rather, the method 100 according to the invention offers the possibility of generating free forms.

FIG. 5 (d) shows a two-dimensional height or depth profile 41 of the structured molding tool surface 24 shown in FIGS. 5 (a) -5 (c), the dimensions of the respective impression structures 27 being recognizable in the depth direction. For example, at least one of the molding structures 27 can have a dimension in the depth direction 29 that is smaller than 1 mm, preferably smaller than 500 nm, more preferably smaller than 100 nm and even smaller than 10 nm. FIG. 5 (e) shows an enlarged section of an exemplarily selected impression structure 27A. The impression structure 27A has several steps 23. The steps 23 have a dimension in the lateral direction 28A and a dimension in the depth direction 29A. For example, a step 23 can have a dimension in the depth direction 29A that is smaller than 1 mm, preferably smaller than 500 nm, more preferably smaller than 100 nm and even smaller than 10 nm. Alternatively or additionally, a step 23 can have a dimension in the lateral direction 28A which is smaller than 1 mm, preferably smaller than 500 nm, more preferably smaller than 100 nm and even smaller than 10 nm.

FIGS. 6 (a) and 6 (c) each show an image of an impression of the structured molding tool surface 24 shown in FIGS. 4 (a) and 4 (c), the structured molding tool surface 24 from FIG. a) represents a negative form of the impression shown in FIGS. 6 (a) and 6 (c). FIGS. 6 (a) and 6 (c) therefore show a non-limiting example of an end product 61 that can be produced or molded by means of the molding tool according to the invention. The molded structures 121 produced in the molded end product 61 correspond to an impression of those discussed above Impression structures 27.

FIGS. 6 (b) and 6 (d) show two-dimensional height and depth profiles 41 of the molded end products 61 shown in FIGS. 6 (a) and 6 (c). As can be seen in the height profiles 41, accordingly also in finished product 61 at least one of the molded structures 121 has a dimension in the depth direction 29 which is smaller than 1 mm, preferably smaller than 500 nm, more preferably smaller than 100 nm and even smaller than 10 nm. The same applies to the dimensions of the molded structures 121 in the lateral direction.

FIG. 7 (a) shows a plan view of an impression of the structured molding tool surface 24 shown in FIG. 5 (a), the structured molding tool surface 24 from FIG. 5 (a) being a negative form of the one shown in FIG. 7 (a) Represents impression. FIGS. 7 (a) and 7 (b) accordingly show a further non-limiting example of an end product 61 that can be produced or molded by means of the molding tool according to the invention with correspondingly molded structures 121, in this example with a concentric arrangement of alternately arranged depressions 121A and elevations 121 B. The shaped structures 121 produced in the shaped end product 61 correspond to an impression of the previously discussed impression structures 27. FIG. 7 (c) shows a two-dimensional depth or height profile of the impression shown in FIG. 7 (a). As can be seen in the height profile 41, at least one of the molded structures 121 in the finished end product 61 accordingly has a dimension in the depth direction 29 that is less than 1 mm, preferably less than 500 nm, more preferably less than 100 nm and can even be smaller than 10 nm. The same applies to the dimensions of the molded structures 121 in the lateral direction.

For the depth of the structures (both the molding structures 21 and the molded structures 121), the finest possible gradation from 0 (actually zero) to a few micrometers can be achieved. Graduations of up to 100 mm are conceivable. Areas between 0-2 mm and between 0-10 mm are advantageous.

Surface expansions of the molding tool surface 24 in the areas described can be implemented reproducibly with the method 100 according to the invention. Several individual, smaller molding tool surfaces 24, for example in the range of a few square millimeters, but also larger or smaller, can be combined with a so-called stitching process to form a larger overall molding tool surface of a few square centimeters. This means that several structured forming tool surfaces (e.g. stamps) can be joined together in order to process larger areas. Roller processes are also possible here. Occasionally, similar structures or mold surfaces are required, which means that so-called step-and-repeat processes can be used later in production for processing entire square meters.

The present invention as well as its advantages and advantageous differences from known methods are to be briefly summarized again in other words below: With the method according to the invention, nano-direct machining becomes greater

Tool components possible. While individual structures were previously made on small elements, larger tool blocks can now be structured directly. The advantages of this are that

(1) no more impressions are necessary, which improves the hardness and service life, and no alignment of the nanostructures in the overall tool is necessary (2) no joints between different tool components are necessary, so that there is no need to align the nanostructures in the tool and there are no reliability problems with thermal replication processes, and

(3) no more special layers for nanostructuring are necessary, so that no additional costs are incurred for coatings and no delamination occurs during thermal processes.

An important feature of the method according to the invention is that any desired structures and shapes can be produced. These include, on the one hand, non-rotationally symmetrical optical elements, which otherwise could not be manufactured using ultra-precision machining or laser direct writing techniques, and, on the other hand, freeform surfaces, i.e. structures of any shape (provided that they can be subtractively manufactured from one beam direction). Examples of this are optical elements such as phase plates, wavefront corrections or digital diffractive patterns. This essential fact makes the technology very universally replaceable for the production of a large number of optical elements and therefore represents a key technology in the production of polymer optical elements.

The product that can be produced with the molding tool can be a Fresnel-like diffractive lens. Here, the grids can be designed continuously, whereby the Fresnel structure comes about. The difference, however, is in the order of magnitude. This is smaller by a factor of 10-100 than with conventional Fresnel-like lenses, which is possible with the method according to the invention, at least with the specified resolution accuracy, edge steepness and achievable corner radii.

The structures can, for example, be written directly from the CAD model into the molding tool (stamp), which can come from simulations of a wavefront calculation or a reserve calculation for warpage and shrinkage for injection molding. No intermediate steps are necessary for this, such as lacquer techniques (lacquer application techniques and any kind of lithography / exposure / etching), molding and copying techniques from the master structures, or integration of partial inserts in holders in the tool. This step of the direct structuring of the tool surfaces is also a special feature, since no additional inserts have to be installed, aligned and fixed in order to avoid a resulting inaccuracy in positioning, eg offset or tilting. And there are no thermal conductivity problems at the transition points through air gaps. This optimizes the conduction and distribution of heat, which significantly simplifies the temperature control of the mold surface.

The invention enables extremely precise molding tools, for example stamps, to be produced for moldings by hot stamping processes, injection molding or injection stamping processes, and nano-imprint lithography processes. The structures can have a lateral and a depth resolution in the submicrometer range, ideally down to the nanometer range. The invention also offers the possibility of producing various shapes with structures with micrometer and submicrometer resolution, especially in mass production, for example of optical elements, for example phase plates, wavefront corrections, digital diffractive patterns or optical lenses, for example Fresnel lenses or diffractive lenses, Fresnel-like diffractive lenses, for example Fresnel lenses for lighting optics in smartphones.

For this purpose, the invention can provide molding tools, for example punches, which have a long service life, high molding accuracy and low wear. Hard materials with high strength and good thermal conductivity can be processed, which can be provided with micro and nanostructures at the same time.

Technologies currently used are not able to structure such materials directly and maintain the required levels of accuracy. The molding tools produced according to the invention can then be molded into the desired material, for example transparent optical materials for Fresnel lenses, for example by hot pressing, embossing / punching, injection compression molding, injection molding, or nanoimprint lithography.

The use of the ion beam according to the invention overcomes the problems of gray scale lithography, as is carried out, for example, with the aid of electron beams or photolithography. There, up to 64 or more gray levels form an edge of the stamp. With the use of the ion beam according to the invention, on the one hand, very steep flanks and, on the other hand, practically smooth, inclined edges are possible, with submicrometer spatial and depth resolution. The invention also relates to a use of an ion beam lithography method for producing a molding tool, wherein the use can have the same features and advantages as the claimed method.

Furthermore, the invention also allows tough and hard hard metals such as titanium to be machined, which conduct heat well and are not very brittle. The inventive A corresponding molding tool, for example a stamp, has a high degree of dimensional accuracy to the optical design or to the functional design according to the intended application. In particular, very steep flanks and bevels can also be implemented, which have a resolution better than 64 or 128 steps and which can have a diameter of several hundred micrometers or even millimeters. The molding tool, for example the stamp, can be produced directly in a hard material that conducts heat well so that the component and the finest structures can be molded precisely and completely, and which can be easily removed from the mold.

Up to now it was only known to structure dielectrics or semiconductors such as silicon with the aid of ion beams in order to use them in plastic replication. However, these conduct heat poorly and / or are very brittle, which makes it difficult to mold the finest structures. In addition, there is an increased risk that such materials will break in use, since although they are very hard, they are not very tough. Compared to other known manufacturing processes in which a mold is manufactured by electrodeposition of a metal (e.g. nickel) on a multi-stage stamp, the process according to the invention offers the advantage that any materials can be used. In principle, almost all materials can be processed with the method according to the invention, provided that no immersion mode is necessary. In this case, strong electromagnetic fields occur, which excludes the processing of magnetic materials. From a toolmaking point of view, however, metals are preferred, many metals having magnetic properties. The method according to the invention can be carried out, for example, with non-magnetic metals, so that an immersion mode can optionally be used. As an alternative to metals, crystalline materials such as silicon, ceramics (multi- and monocrystalline) and other elements can also be processed with the method according to the invention. The problem here is that these have different thermal expansion coefficients than the rest of the structure of the steel tools, which can easily lead to stress fractures or so-called "seizure" if the elements do not run into one another properly.

Metals are therefore particularly advantageous as a material for molding tools, since they have similar coefficients of thermal expansion as the steel tools with which the molding tools are to be used, causing stress fractures or so-called "Scuffing", wedging and the associated increased wear of moving components due to geometrical deviations, including thermal expansion, can be avoided.

Metals also have the advantage of good thermal conductivity. In particular, particularly hard metals (e.g. with a Mohs hardness> 4) can be processed with the ion beam process. Hard metals in particular offer a high degree of dimensional accuracy for functional design in accordance with the intended application, for example for optical design. In addition, hard metals in particular ensure a long service life.

Another advantage of metals is that they can be easily removed from the mold. The inventive structuring of the metal workpiece by means of an ion beam is particularly advantageous, since this type of structuring of metals can achieve a depth resolution of less than 10 miti, ideally up to 10 nm. Thus, molding tools made of hard metal can be structured more precisely with the method according to the invention than with conventional methods for the direct machining of metals. In so doing, structures of any shape, in particular free-form surfaces, can be produced, provided that it can be produced subtractively from one beam direction. In particular, it is also possible to implement very steep flanks and bevels that have a resolution better than 64 or 128 steps and that can be several hundred micrometers or even millimeters in diameter. The structures can be written directly from a digital model, for example a CAD model, into a workpiece, which is particularly advantageous in the case of CAD models from simulations of a wavefront calculation or a reserve calculation for warpage and shrinkage for injection molding production.

Due to the direct structuring of the workpiece with the ion beam, no additional intermediate steps are absolutely necessary for the production of the molding tool, such as paint techniques, molding and copying techniques from the master structures, or the integration of partial inserts in holders in the tool. The step of direct structuring of the tool surfaces is particularly advantageous because no additional inserts have to be installed, aligned and fixed when integrating the molding tool into a production system, which means that inaccuracies in positioning, for example offset or tilting, can be avoided. By eliminating additional inserts, thermal conductivity problems caused by air gaps at transition points are also avoided. This increases the heat conduction and - Distribution optimized, which significantly simplifies the mold surface temperature control.

The above-described embodiments are merely illustrative of the principles of the present invention. It is to be understood that modifications and variations of the arrangements and details described herein will be apparent to other skilled persons. It is therefore intended that the invention be limited only by the scope of protection of the following patent claims and not by the specific details presented herein with reference to the description and explanation of the exemplary embodiments. Although some aspects have been described in connection with a device, it goes without saying that these aspects also represent a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Analogously, aspects that have been described in connection with or as a method step also represent a description of a corresponding block or details or features of a corresponding device.

Claims

1. A method (100) for producing a molding tool (20), the method (100) comprising the following steps:

Providing a workpiece which has a workpiece surface (22) comprising a metal,

Structuring of the workpiece surface (22) by at least partially removing the metal from the workpiece surface (22) by means of an ion beam, so that a micro- or nano-structured workpiece surface is created which forms a structured mold surface (24), the structuring of the workpiece surface (22) is carried out at least in sections with a depth resolution in the submicrometer range of less than 1 mm and / or with a lateral resolution in the submicrometer range of less than 1 mm.

2. The method (100) according to claim 1, wherein the structuring is carried out at least in sections with a depth resolution of less than 500 nm, or of less than 100 nm, or of less than 10 nm.

3. The method (100) according to claim 1 or 2, wherein the structuring is carried out at least in sections with a lateral resolution of less than 500 nm, or of less than 100 nm, or of less than 10 nm.

4. The method (100) according to any one of the preceding claims, wherein the metal has a Mohs hardness of greater than 4.

5. The method (100) according to any one of the preceding claims, wherein the metal is titanium.

6. The method (100) according to any one of the preceding claims, wherein the ion beam has ions of at least one of the materials gold, silicon, carbon, platinum, gallium.

7. The method (100) according to any one of the preceding claims, wherein the structured mold surface (24) has a maximum depth of 0 mm to 100 mm, or from 0 mm to 10 mm, or from 0 mm to 2 mm.

8. The method (100) according to any one of the preceding claims, wherein the structured mold surface (24) has a lateral area in the range between 400 nm ² and 35,200 mm ² or between 400 nm ² and 10,000 mm ² .

9. The method (100) according to any one of the preceding claims, wherein the structuring of the workpiece by means of the ion beam is carried out in such a way that the structured molding tool surface (24) has a free form that can be produced subtractively from one direction.

10. The method (100) according to any one of the preceding claims, wherein the structuring of the workpiece by means of the ion beam is carried out in such a way that the structured mold surface (24) forms a negative form or a positive form for a product which is to be produced with the mold ( 20) can be produced.

11. The method (100) according to claim 10, wherein the product comprises an optical element.

12. The method (100) according to claim 10 or 11, wherein the product has a refractive optical element, or a diffractive optical element, or a reflective optical element.

13. The method (100) according to any one of claims 10 to 12, wherein the product has a diffractive lens or a Fresnel lens or a Fresnel-like diffractive lens.

14. The mold can be produced using a method (100) according to one of the preceding claims.

15. Molding tool (20) for producing an optical element, the molding tool (20) having a structured molding tool surface (24) comprising a metal, the metal having a Mohs hardness of greater than 4, wherein the structured molding tool surface (24) has at least one molding structure (27) with a dimension in a lateral direction (28) in the submicrometer range of less than 1 miti and / or with a dimension in a depth direction (29) in the submicrometer range of less than 1 mm.

16. The molding tool (20) according to claim 15, wherein the impression structure (27) has dimensions in the depth direction (29) of less than 500 nm, or less than 100 nm, or less than 10 nm.

17. The molding tool (20) according to claim 15 or 16, wherein the impression structure (27) has dimensions in the lateral direction (28) of less than 500 nm or less than 100 nm or less than 10 nm.

18. The mold (20) according to any one of claims 15 to 17, wherein the metal is titanium.

19. The molding tool (20) according to any one of claims 15 to 18, wherein the structured molding tool surface (24) has a maximum depth of 0 mm to 100 mm, or from 0 mm to 10 mm, or from 0 mm to 2 mm.

20. The molding tool (20) according to any one of claims 15 to 19, wherein the structured molding tool surface (24) has a lateral area in the range between 400 nm ² and 35,200 mm ² or between 400 nm ² and 10,000 mm ² .

21. The molding tool (20) according to any one of claims 15 to 20, wherein the structured molding tool surface (24) has a free form produced subtractively from one direction.

22. Molding tool (20) according to one of claims 15 to 21, wherein the structured molding tool surface (24) forms a negative form or a positive form for molding the optical element which can be produced by means of the molding tool (20).

23. Molding tool (20) according to one of claims 15 to 22, wherein the optical element is a refractive optical element or a diffractive optical element or a reflective optical element.

24. The molding tool (20) according to any one of claims 15 to 23, wherein the optical element is a diffractive lens or a Fresnel lens or is a Fresnel-like diffractive lens.

25. Mold (20) according to one of claims 15 to 24, wherein the mold (20) has a melting point which is above the melting point or the glass transition temperature of polymers and / or glass.

26. Mold (20) according to one of claims 15 to 25, wherein the structured mold surface (24) is produced by bombardment with silicon ions and / or gold ions and / or carbon ions and / or platinum ions and / or gallium ions.

27. The molding tool (20) according to any one of claims 15 to 26, wherein the molding tool (20) is designed to be used as an insert in a device for molding the optical element from a polymer or a glass.