Optomechanical exposure method and optomechanical exposure device for producing a stochastically structured surface

Abstract

Optomechanical exposure method for producing a stochastically structured surface, in particular a photoresist master, comprising the steps: - coating a substrate (11) to be exposed with photoresist, - arranging a diffuser (10) with a scattering surface structure at a distance (a) from the substrate (11) to be exposed, - exposing the photoresist coating (12) by moving a coherent light beam relative to the substrate (11) and the diffuser (10), characterized in that - speckles occurring when passing through the diffuser (10) are used for stochastic structuring of the surface when exposing the substrate (11), wherein - the distance (a) between the scattering surface of the diffuser (10) and the surface of the substrate (11) to be exposed lies in the near field of the beam optics.

Description

[0001] The invention relates to an optomechanical exposure method and an optomechanical exposure device for producing a stochastically structured surface.

[0002] Diffuse surfaces can be created in a variety of ways. For example, there are laser ablation processes that use high energy density to directly structure copper, brass, or stainless steel surfaces. However, due to the low resolution of the writing instrument, fine structures < 100 µm are not feasible and do not produce adequate optical results. Furthermore, generating the necessary data sets is not trivial and, due to the enormous data volumes, requires stitching, which always carries the risk of detecting connecting seams. Finally, the large structures created in this way also lead to high paint consumption in subsequent series production, making the products expensive and therefore unattractive to the market.

[0003] Another option for creating a diffuse surface is to irradiate a surface with different particles. However, the parameters of grain size and structure height often cannot be adjusted independently and continuously. However, some applications, such as in the display sector, require a defined height distribution for a specific grain size. Furthermore, structures with a high aspect ratio, such as those required for wide-angle scatterers, cannot be realized this way.

[0004] Etching techniques are similar to blasting techniques. Different material combinations of a master and an etching solution can produce different structural properties. However, even here, there is often limited freedom in the choice of surface properties. In addition to the aforementioned weaknesses of existing structuring methods, there is the lack of the possibility of precisely adjustable, anisotropic structuring. Elliptical or linear scatterers with specific axis ratios in the horizontal and vertical directions are often required. These cannot be adjusted with the aforementioned methods, or cannot be adjusted with sufficient precision.

[0005] Using interference lithography, diffusers can currently be created on flat surfaces measuring up to 510 mm × 610 mm by exposing a photoresist to static speckle fields in the ray-optical far field over a large area. This exposure method utilizes the effect that when coherent light of variable lateral extent is passed through a diffuser, speckles are created in the ray-optical far field. Their properties can be precisely adjusted in certain aspects, such as grain size, grain shape, and dose. Speckles are generally referred to as stochastic, granular interference phenomena that can be observed with sufficiently coherent illumination of optically rough object surfaces with unevenness in the object surface.In the classic ray-optical far-field setup, the intensity distribution is determined primarily by the scattering distribution of the diffuser, not by the type of illumination. However, purely optical considerations also result in speckle properties that cannot be independently adjusted. These include the lateral intensity distribution, the grain size distribution, and the tilt of the speckles. The classic ray-optical far-field exposure method therefore has weaknesses on flat substrates, such as inhomogeneity or tilting of the speckles.

[0006] A significant problem with far-field exposure is that the speckles are slanted if the exposure is off-center. This is always the case with larger surfaces. This slant cannot be easily compensated. Therefore, with this far-field method, after a welding process required for the production of sleeves, intrinsically seam-like structures are obtained on the surface. In particular, an easily scalable implementation of the method to large surfaces proves to be difficult or extremely cost-intensive, as it requires very large, high-quality optics. The weaknesses of the far-field method are very apparent on larger surfaces and are therefore less interesting for commercial application. In addition, this exposure method always results in inhomogeneities with regard to the structure depth and structure tilt, which, depending on the structure, have a greater or lesser influence on the scattering function.However, in terms of economic viability and efficiency, this is unacceptable.

[0007] The invention is therefore based on the object of providing an optomechanical exposure method and an optomechanical exposure device for producing a stochastically structured surface, which produce a seamlessly structured photoresist surface on a flat or cylindrical substrate in a particularly uniform, precise and economical manner.

[0008] The object is achieved according to the invention by an optomechanical exposure method according to claim 1 and an optomechanical exposure device according to claim 7. Advantageous developments of the invention are specified in the dependent claims.

[0009] The optomechanical exposure method according to the invention for producing a stochastically structured surface, in particular a photoresist master, comprises as process steps first coating a substrate to be exposed with photoresist, followed by arranging a diffuser with a scattering surface structure at a distance from the substrate and exposing the photoresist coating by moving a coherent light beam relative to the substrate and the diffuser, wherein speckles occurring when irradiating the diffuser are used for stochastic structuring of the surface for exposing the substrate and wherein the distance between the scattering surface of the diffuser and the surface of the substrate to be exposed lies in the ray-optical near field.

[0010] The invention also relates to an optomechanical exposure device for producing a stochastically structured surface, comprising a light source emitting a coherent light beam, a first mirror arranged behind the light source in the propagation direction of the light beam for adjusting and / or moving the light beam, a diffuser arranged behind the mirror in the propagation direction of the light beam, and a substrate plane arranged behind the diffuser at a distance in the region of the optical near field in the propagation direction for receiving a substrate to be exposed.

[0011] To eliminate the problems inherent in the prior art and simultaneously enable simpler and flexible scalability of a seamlessly structured photoresist surface on a substrate in a particularly uniform, precise, and cost-effective manner, the inventors have developed an exposure method and an exposure device that utilizes speckles in the near-field of ray optics to structure surfaces. Furthermore, the cost-effectiveness of exposure is increased, as complex and expensive optics are not required.

[0012] Coating the substrate to be exposed with photoresist involves applying a photosensitive substance to the substrate to be exposed. The coating can be applied to the substrate to be exposed by spraying or, for example, by immersing the substrate to be exposed in a container of photoresist or by treating it with a spin-on process.

[0013] According to the invention, the diffuser with a scattering surface structure is arranged at a defined distance from the substrate to be exposed. According to the invention, this distance lies in the radiation-optical near field. The near field is determined, among other things, by the fact that the intensity distribution is determined by the incident radiation and in particular the distribution of the incident radiation and also depends on the characteristics of the primary diffuser. The usual distances depend on the exposure situation and the scattering behavior of the diffuser, with usual distances for the near field being a few millimeters behind the diffuser. This distance can preferably be between 0.1 mm and 100 mm, more preferably between 0.5 mm and 50 mm, and most preferably between 1 mm and 25 mm. The far field, on the other hand, is understood to be a significantly greater distance, typically from a few decimeters.The near-field beam optics requires precise coordination of illumination, optical beam parameters, diffuser scattering width, and distance to the photoresist. Furthermore, the defined diffuser distance is preferably constant across all exposed surface areas of the substrate in order to achieve uniform surface structuring through homogeneous illumination.

[0014] To expose the substrate, the invention utilizes speckles that occur when light passes through the diffuser to stochastically structure the surface. The optical principle of structuring thus consists in utilizing the speckles that arise when coherent light strikes or penetrates a rough surface. The properties of the speckles can be influenced using various input parameters. For this purpose, the coherence, the power of the light source, and / or the collimation can be adjusted. The grain size and the ellipticity of the speckles can also be influenced by optical measures, such as adjusting the collimation or multiple exposure. By utilizing the ray-optical near-field, the problems related to the inhomogeneity of structural tilt and intensity distribution are eliminated, since exposure in the ray-optical near-field is intrinsically always centered.

[0015] According to the invention, the surface exposure of the photoresist coating is achieved by moving a coherent light beam relative to the substrate and the diffuser. A completely dynamic approach can be chosen, which, in contrast to step-and-repeat exposures, avoids connecting seams. Consequently, the exposure process preferably scans the surface dynamically so that no connecting seams are detectable despite serial writing. In addition, the homogeneity with regard to structure depth, connecting seams, and structure tilt can be optimized compared to previously used step-and-repeat exposures. Furthermore, the exposure process can be intrinsically and virtually seamlessly transferred to a cylindrical substrate. The structure created in this way is stochastic in nature and, in its optical function in the final product, corresponds to an optical diffuser.

[0016] For the purposes of this invention, a coherent light beam is understood to mean a light beam whose coherence length is at least 10 cm, preferably at least 1 m, more preferably at least 10 m, and most preferably at least 100 m. A laser, for example, can be used for this purpose.

[0017] According to the invention, the diffuser is arranged behind the mirror in the direction of propagation of the light beam. A diffuser is an optical component that scatters light. The diffuser can have a surface structure adapted to the requirements. The surface structure can, for example, be homogeneous structuring through irradiation with particles or be formed into an optical grating in any desired manner.

[0018] Behind the diffuser, a substrate plane is arranged to accommodate the substrate to be exposed. The substrate plane is a plane in which the surface of the substrate can be positioned. In the case of a cylindrical diffuser and substrate, the substrate plane is the tangential plane of the cylindrical diffuser and substrate that is orthogonal to the light beam. Consequently, in this case, the diffuser is arranged between the last lens and the substrate. In the case of a flat substrate, the diffuser is arranged between the last deflection mirror and the substrate plane. This arrangement ensures that the distance between the diffuser and the substrate is sufficiently small to be in the beam-optical near field.

[0019] In principle, the shape of the diffuser and the substrate can be freely selected. For example, the diffuser or the substrate can be cylindrical. According to a preferred embodiment of the exposure method according to the invention, the diffuser and the substrate are cylindrical or flat. This embodiment can make dynamic scanning particularly simple. The inner diameter of the cylindrical diffuser is preferably at most 10%, more preferably at most 5%, and most preferably at most 2% larger than the outer diameter of the substrate or of the substrate to be arranged in the substrate plane.

[0020] It is particularly preferred for the cylindrical diffuser to be arranged so as to at least partially, preferably completely, surround the cylindrical substrate, and / or for the exposure to take place by rotating the cylindrical diffuser and the cylindrical substrate about a common axis of rotation and / or for the light beam to be displaced parallel to the central longitudinal axis of the substrate. In the case of a design of a cylindrical diffuser that at least partially, preferably completely, surrounds the substrate, it is also possible for only the substrate to be rotated while the cylindrical diffuser remains stationary, in particular in order to produce a linear diffuser. Furthermore, it is also conceivable to rotate the cylindrical diffuser and the substrate at different speeds so that a relative speed is produced between the substrate and the diffuser. The ratio of the rotational orAngular velocities can be chosen arbitrarily, whereby in principle one of the two velocities can also be zero.

[0021] In an embodiment with a cylindrical diffuser completely surrounding the substrate, it may be advantageous to rotate both the cylindrical diffuser and the cylindrical substrate about a common axis of rotation in order to sequentially, structurally seamlessly and dynamically expose the surface of the cylindrical substrate with a speckle pattern. In this case, "seamless" can be understood to mean homogeneous structuring in various aspects, such as the visual appearance, the scattering parameters, in particular the angle and / or ellipticity, the grain size, the tilt of the structures and / or the depth distribution of the structures. Consequently, due to this embodiment of the method according to the invention, a seamless structuring of the surface can be formed by means of the speckles occurring due to the cylindrical diffuser.

[0022] In a preferred embodiment of the exposure method according to the invention, the dynamic exposure can provide for the movement of the light beam parallel to the central longitudinal axis of the substrate. For this purpose, it is advantageous to move the light beam in a helical manner over the cylindrical diffuser. The light beam is thus guided evenly over the surface in order to achieve seamless structuring through correspondingly uniform exposure. Thus, by optically scanning the cylindrical diffuser, a speckle pattern that is static with respect to the photoresist and only modulated in intensity can be exposed, for example in a helical manner on the entire substrate within a single dynamic process. It is also possible to expose the cylinder in parallel paths along the axis of rotation and to carry out exclusively rotary steps. The connection points orThe seams of the individual lines now depend only on the intensity, but no longer on the coherent superposition, and can be selected very precisely using the beam diameter. Accordingly, a small stepover per round / line or a small overlap per full revolution / line can be selected, for example, less than 10%, particularly preferably less than 5%, and most preferably less than 2% of the width or area of ​​the exposure.

[0023] According to an advantageous embodiment of the exposure method according to the invention, surface structures can be formed in the photoresist during exposure due to the speckles, wherein a structure depth of the formed surface structures is adjusted by means of the intensity of a light source of the light beam and / or by means of the rotational speed of the cylindrical diffuser and the cylindrical substrate and / or a grain size of the formed surface structures is adjusted by means of multiple exposure. In this case, for example, the height of the structures can be adjusted via the intensity, the rotational speed and / or the dose. The grain size of the structures can preferably be continuously adjusted within a specific range between 5 µm and 100 µm, in particular by means of the optical setup.Additionally, this exposure method allows the use of light sources with lower coherence, as the resulting path length differences between the interfering partial beams are small. The critical surface parameter to be adjusted can be the amplitude of the depth distribution, as this directly influences the scattering angle. Consequently, the optical parameters of the resulting surface can be freely adjusted.

[0024] According to a preferred embodiment of the exposure device according to the invention, the distance a 12 dtan(12ϑ)≥a , where d is the laser's illumination width and θ is a scattering angle. The diffuser can have an entrance surface through which the light beam with the illumination width d enters, and an exit surface which can be designed such that the light beam exits at a scattering angle θ, resulting in speckles. This inequality describes the maximum distance a that is permitted so that the distance between diffuser and substrate lies in the beam-optical near field. This allows each exposed point on the photoresist to be exposed using the identical angular spectrum specified by the diffuser. This has the advantage that no speckles are formed that are oblique to the beam direction. Particular caution may be required when dynamically shifting the illumination so that the wave-optical speckle pattern remains static and, consequently, only the brightness changes.In the case of a cylindrical diffuser, this can be achieved, for example, by focusing the corresponding beam direction consistently on the axis of rotation.

[0025] In order to focus and / or collimate the light beam, a lens can be arranged in front of the diffuser in the propagation direction of the light beam. Furthermore, more than one lens and / or at least one lens as well as further optical components can be provided, which preferably form a lens system that is particularly preferably arranged completely behind the light source and in front of the diffuser. The lens or lens system can basically be provided for the defined, collimated expansion and / or focusing of the light beam emitted by the light source. The lens or lens system is preferably formed such that the incident light rays always impinge orthogonally on the substrate surface to be exposed. For a flat substrate surface, the lens or lens system can preferably be formed such that the light rays impinging on the substrate surface are collimated.For flat substrates, the lens system is particularly preferably designed such that the collimation is adjusted in front of the diffuser such that no additional lens is required in front of the diffuser. For a curved and, in particular, a cylindrical substrate surface, the lens or lens system is preferably designed such that the light rays incident on the substrate surface are perpendicular to the substrate surface.

[0026] In the case of a cylindrical exposure, the lens can preferably have a focal length that is sufficiently large to ensure appropriate adjustment of the focal point. The focal point is preferably located behind the diffuser, so that the lens focuses through the diffuser. Particularly preferably, the light beam strikes the surface of the cylindrical diffuser perpendicularly. Likewise, the focal point is preferably located substantially in the axis of rotation of the cylindrical diffuser, with a deviation from the axis of rotation being particularly preferably less than 10 mm and most preferably less than 2 mm.

[0027] According to an advantageous development of the exposure device according to the invention, a lens system, and in particular a beam expansion system, can be arranged behind the light source in the propagation direction of the light beam. The system has at least two lenses, each with different focal lengths, wherein the focal length of the first lens is preferably shorter than the focal length of the second lens. Such a beam expansion system is particularly advantageous for exposing a flat substrate, but can also be used for exposures on cylindrical substrates. The beam expansion system can be provided to flexibly expand and collimate the beam diameter of the light beam. For this purpose, the first lens must have a shorter focal length than the second lens. Another parameter that can be adjusted with the beam expansion system is the collimation of the light beam.This allows for optimized collimation for the application. The optimized collimation can be linked to certain conditions regarding the optical stability of the speckles during dynamic spot movement across the stochastic surface of the diffuser. To achieve specific speckle dynamic properties, a non-optimized collimation of the light beam can also be used, for example, where the two lenses are not spaced at a distance equal to the sum of the lenses' focal lengths.

[0028] According to an advantageous embodiment of the exposure device according to the invention, at least two mirrors can particularly preferably be arranged behind the light source in the propagation direction of the light beam in order to ensure precise adjustment of the light beam. The exposure device particularly preferably has a mirror to enable the light beam to be displaced laterally. Furthermore, it is preferred that, in the case of a flat substrate, at least two, and particularly preferably exactly two, mirrors are provided for moving the light beam in two axes, and, in the case of a cylindrical substrate, at least one mirror, and particularly preferably exactly one mirror, is provided for moving the light beam laterally, as well as a rotation of the diffuser and the substrate plane.

[0029] To optimally control the light beam, it may be advantageous to provide two degrees of freedom that can be controlled in a synchronized, mechanically stable, angle-stable, torsion-free, and / or vibration-free manner. One of the degrees of freedom can be linear, the other rotational. On the linear degree of freedom, such as a movable platform, the mirror and lens can be arranged such that the laser beam can be moved along the rotation axis.

[0030] Preferably, the rotation axis is rotatable, so that the entire surface of the cylindrical substrate above the cylindrical diffuser can be reached and scanned in homogenizing patterns by means of a synchronous movement, while the resulting speckles in the photoresist on the surface of the substrate are exposed in a fixed location and only with intensity modulation. The relative speed between the cylindrical substrate and the cylindrical diffuser can be greater than, less than, or equal to zero.

[0031] In a preferred embodiment of the exposure device according to the invention, the mirror can be arranged on a movable mirror platform and the lens on a movable platform and positioned such that the lens is focused on the rotational axis of the cylindrical substrate. The light beam, which is preferably collimated along one axis, and most preferably collimated along two axes, can be deflected orthogonally via the dynamically movable mirror. The lens preferably focuses the light beam on the rotational axis of the cylindrical substrate. The lens can also be movable synchronously with the mirror, for example, via a mechanically fixed connection.Stabilization of the laser power, for example via an acousto-optical modulator with the detector and / or the control path, can be provided, since this exposure method is a serial process in which the fluctuations are not integrated but recorded linearly.

[0032] In an advantageous development of the exposure device according to the invention, the lens can be a cylindrical lens and / or the diffuser a stochastic phase mask. The cylindrical lens has the advantage of focusing the light only in one axis. Consequently, the cylindrical lens can be used to form a laser line, by means of which the surface can be scanned more quickly than with a conventional convex lens, which focuses the light onto a point. A stochastic phase mask can be understood as a special type of optical transmission grating. The stochastic phase mask can, for example, be formed from quartz glass into which a periodic structure, and in particular periodic linear depressions with a defined spacing, are etched. These depressions behave optically like a grating, whereby interference effects can occur as a result of laser exposure.Preferably, the stochastic phase mask is transparent.

[0033] In principle, an advantageous embodiment of the exposure device according to the invention can provide that the diffuser has a scattering angle of less than 10° and / or is homogeneously structured and / or completely deflects the wavelength of the light source used for exposure in order to avoid direct transmission at the wavelength used. In this case, for example, a proportion of more than 95% of the transmitted light can be scattered. Particularly preferably, more than 99% of the transmitted light is scattered. A homogeneous structuring is understood to mean a structuring that has consistent properties across the surface, in particular a consistent scattering width, scattering direction, seamlessness and / or uniform grain size. Likewise preferably, the diffuser is only slightly absorbent and particularly preferably essentially transparent.

[0034] In principle, any type of light source with a sufficiently high coherence length can be used. Lasers are preferably used here, with the wavelength of the laser being freely selectable. The laser can be a continuous wave laser or a pulsed laser. According to a preferred embodiment of the exposure device according to the invention, the light source of the coherent light beam can be a monochromatic laser, which particularly preferably emits in the UV range. The UV range is understood to be a range in the optical spectrum whose wavelengths are shorter than the wavelengths visible to humans. This can usually be understood to mean a spectral range from 100 nm to 380 nm. A monochromatic laser can be understood to be a laser that emits narrowband light, with particularly preferably a single spectral color, such as 349 nm.The advantage of a UV laser is that a wide variety of materials exhibit a high absorption rate in the UV range. This makes it suitable for applications requiring high contrast or minimal heat generation. The laser is preferably a solid-state laser, and a diode laser is particularly preferred. However, the use of a gas laser is also conceivable.

[0035] An embodiment of the optomechanical exposure device according to the invention is explained in more detail below with reference to a drawing. Fig. 1 shows a schematic representation of an optical system of an optomechanical exposure device for a cylindrical substrate; Fig. 2 shows a schematic representation of an optical system of an optomechanical exposure device for a flat substrate.

[0036] The basic components of an optical system of an optomechanical exposure device 1 are shown by way of example in the Fig. 1. The basic components include a light source 2, a beam expansion system 3, a mirror 6, a lens 8 for focusing and / or collimating, and a diffuser 20.

[0037] The light source 2 in this embodiment is a monochromatic UV laser. The laser emits a coherent light beam 21 toward the beam expansion system 3.

[0038] The beam expansion system 3 is arranged behind the light source 2 in the propagation direction of the light beam 21. The beam expansion system 3 comprises a first lens 4 and a second lens 5. The first lens 4 has a shorter focal length than the second lens 5 in order to expand the light beam 21. The first lens 4 has a focal length of 40 mm, while the second lens 5 has a focal length of 80 mm. This combination thus doubles the diameter of the light beam 21. In order to adjust the collimation of the light beam 21 as desired, the second lens 5 is arranged on a movable platform (not shown in the figure).

[0039] After the beam expansion system 3, the expanded light beam 21 hits the mirror 6. The mirror 6 is arranged on a movable and rotatable mirror platform 7 in order to subsequently adjust and move the light beam 21 as desired.

[0040] Lens 8 is arranged behind mirror 6 in the propagation direction of light beam 21. Lens 8 is mounted on a movable lens platform 9, with mirror platform 7 and lens platform 9 coupled via a mirror-lens platform 13 for precise parallel and synchronous movement. Lens 8 is a cylindrical lens for forming a line from light beam 21.

[0041] In the following, the diffuser 10 is arranged behind the lens 8 in the propagation direction of the light beam 21. The diffuser 10 is a stochastic phase mask. The diffuser 10 also has a scattering angle of 5°, is homogeneously structured, and completely deflects the light beam 21 of the light source 2 used for exposure. Furthermore, the diffuser 10 is cylindrical in shape.

[0042] The surface of a substrate 11 to be exposed is arranged in the substrate plane SE. Furthermore, the surface of the substrate 11 is coated with photoresist 12. The substrate 11 is cylindrical in shape.

[0043] Consequently, the diffuser 10 is arranged at a distance a between the lens 8 and the substrate 11. This distance a ensures that speckles are generated in the ray-optical near field to structure the surface of the substrate 11. The cylindrical diffuser 10 is arranged in a stationary manner surrounding the cylindrical substrate 11, and exposure is achieved by rotating the cylindrical diffuser 10 and the cylindrical substrate 11 about a common axis of rotation RA and shifting the light beam 21 parallel to the central longitudinal axis of the substrate 11, wherein the axis of rotation RA and the central longitudinal axis coincide here for geometric reasons.

[0044] The exposure of the photoresist coating 12 is achieved by moving a coherent light beam 21 relative to the substrate 11 and the diffuser 10. For the exposure of the substrate 11, speckles occurring when passing through the diffuser 10 are used to stochastically structure the surface. The light beam 21 is moved helically over the cylindrical diffuser 10. The speckles created by the cylindrical diffuser 10 create a seamless surface pattern in the photoresist 12 of the cylindrical substrate 11.

[0045] A second embodiment in Fig.2 differs from the first embodiment in that, for exposing the photoresist coating 12 of a flat substrate 11, two mirrors 6a, 6b are provided for steering the light beam 21 across the substrate plane SE. The mirrors 6a, 6b are aligned perpendicular to each other in order to scan the substrate plane SE. In this embodiment, a further lens 8 is omitted, since the light beam 21 already strikes the flat substrate plane SE of the substrate 11 perpendicularly and collimated by the optics of the beam expansion system 3. The diffuser 10 is also flat in this embodiment. List of reference symbols 1 Optomechanical exposure device 2 light source 21 Light beam 3 Beam expansion system 4 First lens 5 Second lens 6, 6a, 6b Mirror 7 Mirror platform 8 lens 9 lens platform 10 Diffuser 11 Substrat 12 Photoresist 13 Mirror-lens platform a distance SE substrate level RA rotation axis

Claims

[1] Optomechanical exposure method for producing a stochastically structured surface, in particular a photoresist master, comprising the steps: - coating a substrate (11) to be exposed with photoresist, - arranging a diffuser with a scattering surface structure at a distance (a) from the substrate (11) to be exposed, - exposing the photoresist coating (12) by moving a coherent light beam relative to the substrate (11) and the diffuser (10), characterized by , that - for exposing the substrate (11), speckles occurring when irradiating the diffuser (10) are used for stochastic structuring of the surface, whereby - the distance (a) between the scattering surface of the diffuser (10) and the surface of the substrate (11) to be exposed lies in the ray-optical near field. [2] Optomechanical exposure method for producing a stochastically structured surface according to claim 1, characterized by that the diffuser (10) and the substrate (11) are cylindrical. [3] Optomechanical exposure method for producing a stochastically structured surface according to claim 2, characterized by in that the cylindrical diffuser (10) is arranged surrounding the cylindrical substrate (11) and the exposure is carried out by rotating the cylindrical diffuser (10) and the cylindrical substrate (11) about a common axis of rotation and / or displacing the light beam parallel to the central longitudinal axis of the substrate (11). [4] Optomechanical exposure method for producing a stochastically structured surface according to claim 2 or 3, characterized by that the light beam (21) is moved helically or linearly over the cylindrical or flat diffuser (10). [5] Optomechanical exposure method for producing a stochastically structured surface according to at least one of claims 2 to 4, characterized by that a seamless structuring of the surface of the cylindrical or flat substrate (11) is formed by means of the speckles occurring through the cylindrical or flat diffuser (10). [6] Optomechanical exposure method for producing a stochastically structured surface according to one of the preceding claims, characterized bythat during exposure, surface structures are formed in the photoresist (12) due to the speckles, wherein a structure depth of the surface structures formed is adjusted by means of the intensity of a light source (2) of the light beam (21) and / or by means of the rotation speed of the cylindrical diffuser (10) and the cylindrical substrate (11) and / or the scanning speed of the flat substrate (11) and / or a grain size of the surface structures formed is adjusted by means of multiple exposure and / or adjusting the optical beam parameters. [7] Optomechanical exposure device (1) for producing a stochastically structured surface, with - a light source (2) emitting a coherent light beam (21), - a mirror (6, 6a) behind the light source (2) in the direction of propagation of the light beam (21) for adjusting and / or moving the light beam (21), - a diffuser (10) arranged behind the mirror (6) in the direction of propagation of the light beam (21) and - a substrate plane (SE) arranged at a distance (a) in the region of the optical near field in the propagation direction behind the diffuser (10) for receiving a substrate (11) to be exposed. [8] Optomechanical exposure device (1) for producing a stochastically structured surface according to claim 7, characterized by that the distance a 12 dtan(12ϑ)≥a where d is an illumination width of the laser and θ is a scattering angle. [9] Optomechanical exposure device (1) for producing a stochastically structured surface according to at least one of claims 7 or 8, characterized by that a lens (8) focusing and / or collimating the light beam (21) is arranged behind the mirror (6) in the propagation direction of the light beam (21). [10] Optomechanical exposure device (1) for producing a stochastically structured surface according to at least one of claims 7 to 9, characterized by in that a beam expansion system (3) is arranged behind the light source (2) in the propagation direction of the light beam (21), which has at least two lenses (4, 5) each with different focal lengths, wherein the focal length of the first lens (4) is shorter than the focal length of the second lens (5). [11] Optomechanical exposure device (1) for producing a stochastically structured surface according to at least one of claims 7 to 10, characterized by that at least two mirrors (6, 6a, 6b) are arranged orthogonally to each other in order to guide the light beam (21) over the substrate plane (SE). [12] Optomechanical exposure device (1) for producing a stochastically structured surface according to at least one of claims 7 to 11, characterized bythat a mirror (6) is arranged on a movable mirror platform (7) and a lens (8) is arranged on a movable lens platform (9) and positioned such that the lens (8) is focused on the axis of rotation (RA) of the cylindrical substrate (11). [13] Optomechanical exposure device (1) for producing a stochastically structured surface according to at least one of claims 7 to 12, characterized by that the lens (8) is a cylindrical lens and / or the diffuser (10) is a stochastic phase mask. [14] Optomechanical exposure device (1) for producing a stochastically structured surface according to at least one of claims 7 to 13, characterized by that the diffuser (10) has a scattering angle of less than 10° and / or is homogeneously structured and / or completely deflects the wavelength of the light source (2) used for exposure. [15] Optomechanical exposure device (1) for producing a stochastically structured surface according to at least one of claims 7 to 14, characterized by that the light source (2) of the coherent light beam (21) is a monochromatic laser which emits preferably in the UV range.

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