Methods and systems for manufacturing embossing apparatus using etch masks

Abstract

A method of manufacturing a structured embossing cylinder for an embossing system includes the steps of: providing a hard-coat embossing roll having a cylindrical core and a hard coat on the cylindrical core, the hard coat having a thickness in a range between 1 pm and 10 pm, the hard coat having a surface roughness value Ra of less than 100 nm; depositing a mask layer on the hard coat, the mask layer having a thickness equal to or less than 100 nm; removing material from the mask layer to form at least one opening; and etching to remove material from the hard coat at the at least one opening of the mask layer to form a surface cavity in the hard coat at the at least one opening, the surface cavity forming a structured embossing feature within the hard coat, thereby forming a structured embossing cylinder.

Description

Technical Field

[0001] This invention relates to the field of embossing equipment such as embossing rollers, rolls, cylinders, plates, and tubes, and more specifically, to the field of methods for manufacturing embossing equipment with embossed structures on the outer surface and corresponding manufacturing systems, for example, embossing equipment for embossing packaging materials, and using such embossing equipment to emboss packaging materials. Background Technology

[0002] In the prior art, different methods have been proposed to manufacture embossing rollers for different application areas. For example, embossed or structured packaging foils have been used for packaging in various industrial sectors, such as tobacco products, food such as chocolate, sweets, and candies, as well as packaging foils for devices such as electronic components and equipment, jewelry, watches, or for gift packaging in any retail sector. For example, so-called liners with specific patterns have been used for aesthetic and protective purposes, which can be wrapped around cigarettes, cigars, and chocolates. Embossing rollers can be used in continuous roll-to-roll (R2R) manufacturing processes, where thin foil is embossed with embossed patterns, which may include metallic elements, permeable conductive elements, non-metallic elements, dielectric elements, etc. Another application area is the use of thermoplastic films to create embossed patterns through thermal embossing processes, such as R2R or roll-to-plate (R2P), such as thermal embossing of thermoplastic polymers. For example, see Peng et al.'s "MicroHot Embossing of Thermoplastic Polymers: a Review," Journal of Micromechanics and Microengineering, Vol. 24, No. 1, p.013001, 2013.

[0003] U.S. Patent No. 9,579,924 (the entire contents of which are incorporated herein by reference) describes a method for manufacturing an embossing roller assembly with convex and concave rollers, the structural elements of which have specific structural features with respect to arbitrary deviations in linear and angular dimensions. The structure of this embossing roller assembly is independently manufactured by a laser device L12, which has a laser 12 and a deflection unit 14, which may include a beam splitter and an acousto-optic modulator or electro-optic modulator or polygon mirror. The deflection unit 14, focusing optics 15, and deflection mirror 16 form an engraving unit 17, which is linearly movable along the x-axis. The workpiece is driven by a driver 23, denoted by a rotation angle φ. By combining the linear displacement of the engraving unit with the rotation of the rollers, a constant helix SL is produced, allowing for uniform machining.

[0004] Furthermore, U.S. Patent No. 8,435,373 (the entire contents of which are incorporated herein by reference) describes different R2R processes / apparatus for forming desired patterns on a flexible substrate by removing and / or adding material, wherein a rotational patterning tool with an embossed surface (with relief) is performed in the roll-to-roll embossing process, such as for an in-situ mask layer, which can be made of a variety of materials and various techniques suitable for forming polymer three-dimensional (3D) relief patterns.

[0005] Furthermore, U.S. Patent No. 9,993,895 (the entire contents of which are incorporated herein by reference) describes a laser processing method for engraving embossing rollers coated with a very hard surface coating, such as amorphous tetrahedral carbon (Ta-C), to provide two superimposed, very small embossed structures, the size of which can be less than one micrometer, preferably having a depth of 300 nm. This allows the embossed foil to exhibit different visible multicolor optical diffraction effects.

[0006] Furthermore, U.S. Patent Publication No. 2017 / 0066079 (the entire contents of which are incorporated herein by reference) describes an apparatus for projecting a femtosecond or picosecond laser beam mask onto a substrate surface, wherein the laser beam (2) generates a laser beam pulse having an extended laser beam cross-section or a reduced laser beam cross-section at a position on the optical axis, wherein specific vacuum containers 18, 20, and 23 are used to avoid the formation of plasma at the positions of laser focal spots 17, 19, and 22, and one of the vacuum containers 20 has a pinhole aperture 26 close to the workpiece (surface 12 of the substrate 13 to be laser ablated).

[0007] However, despite all the aforementioned improvements to the processes for manufacturing embossing equipment (such as rollers, cylinders, or tubes) and their diverse applications, there remains a need for novel and substantially improved methods and the resulting embossing equipment, particularly for providing embossing equipment such as rollers or tubes with substantially improved durability and lifespan. For example, one problem is the considerably high surface roughness on other planar or curved inner surfaces when removing material using laser-based methods (e.g., laser engraving or ablation), especially for surfaces located within the embossed structure itself. This can lead to high abrasion and undesirable optical effects in the final embossed film and foil, such as causing optical blurring and reducing the optical quality of these structures. Another problem is the effect of overheating when using laser-based methods to remove material, which can cause changes in the material properties of the coating, negatively impacting surface hardness and structural integrity. Therefore, there is an urgent need for robust and improved methods to produce structured embossed or die structures, such as embossed tubes, rollers, or tubes. Summary of the Invention

[0008] According to one aspect of the invention, a method for manufacturing a structured embossing cylinder for an embossing system is provided. Preferably, the method includes the steps of: providing a hard-coated embossing roller having a cylindrical core and a hard coating on the cylindrical core, the thickness of the hard coating being in the range of 1 µm to 10 µm, and the surface roughness value Ra of the hard coating being less than 100 nm; and depositing a mask layer on the hard coating, the thickness of the mask layer being equal to or less than 100 nm. Furthermore, preferably, the method further includes the steps of: removing material from the mask layer to form at least one opening; and removing material from the hard coating at at least one opening in the mask layer to form a surface cavity at the at least one opening, the surface cavity forming a structural embossing feature within the hard coating, thereby forming a structured embossing cylinder. According to another aspect of the invention, the step of removing material from the mask layer can be performed by laser ablation or electron beam structuring.

[0009] According to another aspect of the invention, a structured embossing apparatus is provided. Preferably, the structured embossing apparatus comprises: a substrate; an adhesive layer on the substrate; a hard coating layer on the adhesive layer, the thickness of the hard coating layer being in the range of 1µm to 10µm, and the Ra roughness value of the hard coating layer being less than 100nm; a mask layer on the hard coating layer, the thickness of the mask layer being less than 50nm; and an embossing structure disposed in the surface of the hard coating layer, the embossing structure penetrating the hard coating layer. Furthermore, preferably, the depth of the surface cavity formed by the embossing structure is between 50nm and 10µm, the width of the surface cavity is between 100nm and 10µm, and the ratio between the depth and width of the cavity is in the range of 0.1 to 2.

[0010] According to another aspect of the invention, a method for manufacturing a structured embossing cylinder for an embossing system is provided. Preferably, the method includes the steps of: providing a hard-coated embossing roller having a cylindrical core and a hard coating on the cylindrical core, the thickness of the hard coating being in the range of 1µm to 10µm, and the surface roughness value Ra of the hard coating being less than 100nm; depositing a mask layer on the hard coating, the thickness of the mask layer being equal to or less than 100nm; performing electron beam writing on a provided electron beam photoresist layer above the top of the mask layer; developing and removing the electron beam photoresist layer to expose the mask layer; etching the mask layer using an etchant that does not affect the hard coating; and etching the hard coating to form surface cavities in the hard coating, the surface cavities forming structural embossing features in the hard coating.

[0011] According to one aspect of the invention, an injection mold is provided. Preferably, the injection mold comprises: a substrate; an adhesive layer on the substrate; a hard coating layer on the adhesive layer, the thickness of the hard coating layer being in the range of 1 µm to 10 µm, and the Ra roughness value of the hard coating layer being less than 100 nm; an inorganic hard mask layer on the hard coating layer, the thickness of the inorganic hard mask layer being less than 100 nm; and a mold cavity disposed in the surface of the hard coating layer, the mold cavity penetrating the mask layer, and wherein the depth of the surface opening formed by the mold cavity is between 50 nm and 7 µm, and the width of the surface opening is between 100 nm and 10 µm. The above and other objects, features, and advantages of the invention, as well as the ways in which they are realized, will become more apparent from the following description and appended claims by referring to the accompanying drawings, which illustrate some preferred embodiments of the invention, and the invention itself will be best understood. Attached Figure Description

[0012] The accompanying drawings (incorporated herein and forming a part of this specification) illustrate presently preferred embodiments of the invention and, together with the general description given above and the detailed description given below, serve to explain the features of the invention.

[0013] Figure 1A and Figure 1B A flowchart and aspects thereof are shown of an exemplary method for manufacturing embossing equipment 200, 200a, wherein: Figure 1A A schematic overview of the steps of a method for manufacturing embossing equipment 200, 200a (shown in variations as embossing cylinder, roller and drum 200 or embossing plate 200a) according to one aspect of the invention is shown. Figure 1B The basic layers of (hard) coatings 20, 30, 32, 34, 36 and 40 on the top of a metal cylinder, core or substrate 10 are shown.

[0014] Figures 2A to 2C A cross-sectional view of a substrate 10 for processing, such as a cylinder, drum, or roller, is shown, on which multiple layers are deposited as a multilayer structure, wherein: Figure 2A A cross-sectional view of a multilayer structure is shown before any material is removed from multiple layers, including an adhesion layer 20, a first inner structural support layer 32 made of a hard material coating, a first mask layer 42, a second outer structural support layer 36, and a second mask layer 46, allowing the formation of multilayered three-dimensional openings in an embossing apparatus by sequentially performing a mask removal step (removing portions of mask layers 42 and 46, respectively) and an etching step (removing material from structural support layers 32 and 36); Figure 2B An embossing roller, roll, or cylinder 200 is shown, wherein a multi-layer structure 210 is formed by a series of laser ablation and etching steps; Figure 2C A cross-sectional view of the multi-layered structure is shown.

[0015] Figures 3A to 3C An exemplary cross-sectional view of a substrate, roller, or roll 10 with a multi-layer hard coating process is shown, wherein: Figure 3A This demonstrates no etch attack. Figure 3B It shows a layer with one etched layer. Figure 3C It shows a structure with three etched layers.

[0016] Figure 4A and Figure 4B Exemplary and schematic systems for plasma etching cylindrical apparatus are shown, the system being used to place a substrate, roller, or tube 10 to be dry-etched by plasma etching apparatus 400, wherein, Figure 4A This is a side view of the cross section. Figure 4B This is a top view of the cross-section.

[0017] Throughout this document, the same reference numerals are used where possible to denote common elements in the accompanying figures. Furthermore, the images in the figures have been simplified for illustrative purposes and may not be drawn to scale. Detailed Implementation

[0018] First, an exemplary embodiment is used to explain the manufacture of equipment that can be used in embossing, molding, or replication processes, such as an embossing roller, cylinder, or drum 200, or a mold 200a having one or more cavities. Figure 1AAn exemplary schematic diagram of the method is shown. A cylindrical metal cylinder, core, or substrate 10 is provided as the substrate for the embossing roller. The diameter of the cylindrical metal cylinder, core, or substrate 10 can be in the range of 50 nm to 500 nm, but other diameters are also possible. Next, the cylindrical metal core or substrate 10 is processed to have an outer cylindrical surface 12 with a smooth surface and a specific hardness. Preferably, the metal core or substrate 10 has been processed to give it a surface roughness parameter (RA) preferably less than 100 nm, more preferably in the range of 10 nm to 50 nm. Regarding hardness, the core or substrate 10 is selected from a material such that the outer cylindrical surface 12 should have a specific hardness value higher than 0.3 GPa (approximately equal to 300 Vickers hardness). This hardness value and surface roughness value are preferred features because values ​​within these ranges will allow the manufacture of embossing rollers with specific durability, allow for operation and required embossing pressure, and will also allow the manufacture of embossed structures with a certain grain size, as explained further below. For example, the surface roughness of the outer cylindrical surface 12 needs to be significantly better, i.e., smaller than the roughness of the embossed pattern to be manufactured. Some aspects of the methods discussed herein describe different processing steps based on cylindrical elements (e.g., cylinders, cores, or substrates 10 made of metal or ceramic), but planar devices 10a with outer surfaces 12a (e.g., flat plates, sheets, or planar substrates made of metal or ceramic materials) can also be processed using methods similar to those used in manufacturing embossed sheets, panels, or stampings, injection molds with cavities, or forming castings 200a.

[0019] In one variation, the core or substrate 10 is a hollow cylinder with a transverse perforation along its axis of rotation, thereby providing a lighter embossing device 100, or the embossing device 200 can be more easily mounted or installed to bolts or rods for mounting on an embossing machine or other machinery, or the embossing device 200 can be used to mount a rotary bearing in the transverse perforation. In another variation, the core or substrate 10 does not need to be made of metal, but can be a composite material, such as a hard metal material, a sintered material, such as, but not limited to, a cermet.

[0020] Subsequently, the metal cylinder or core 10 is processed through a cleaning step S10, wherein the outer surface 12 of the core 10 is degreased and thoroughly cleaned. For example, the cleaning step S10 may include subjecting the metal cylinder or core 10 to a cleaning device, wherein the cylinder is cleaned by complete immersion in a bath of softened water and a cleaning agent, which is a cleaning agent from a specialized cleaning machine capable of generating ultrasonic cleaning cycles. Subsequently, as the cleaning agent is removed from the surface, an oxidation inhibitor may be used in a final rinsing step. The cleaned metal cylinder or core 10 is then provided to the vacuum chamber of a deposition system, such as a physical vapor deposition (PVD) apparatus or system with a coating cavity, for further processing.

[0021] Next, the coating cavity is evacuated and heated, causing the metal cylinder, core, or substrate 10 to rotate about its axis of rotation. Next, the surface of the metal cylinder, core, or substrate 10 undergoes a plasma cleaning process using, for example, argon plasma to activate the surface and remove any organic residues remaining on it before coating deposition. Next, in step S20, the adhesion layer 20 is deposited onto the outer cylindrical surface 12 of the metal cylinder or core 10 using PVD or chemical vapor deposition (CVD), such as reactive sputtering deposition. Step S20 can be performed by rotating the cylindrical metal cylinder, core, or substrate 10 about its axis of rotation using a rotating device while exposing the cylindrical surface 12 of the substrate 10 to a high-energy plasma contained and maintained by a magnetic field between the top and bottom electrodes of the plasma treatment cavity. Preferably, the adhesion layer 20 is an inorganic material, such as TiN or another nitride (e.g., but not limited to CrN) or oxide, and a pure metal layer (e.g., but not limited to Cr and Ti), and the thickness of the adhesion layer 20 can be between tens and hundreds of nanometers, for example, preferably less than 500 nm, more preferably less than 200 nm, and even more preferably in the range of 100 nm and 200 nm.

[0022] Next, in step S30, as Figure 1BAs shown, a hard coating or structural support layer 30 is deposited onto the adhesion layer 20, preferably into the same plasma processing cavity used for depositing the adhesion layer 20, for example without opening the processing cavity, while the cylindrical metal cylinder or core or substrate 10 having the adhesion layer 20 rotates about its axis of rotation. The structural support layer 30 is significantly thicker than the adhesion layer 20, but preferably less than 20 µm; for example, the thickness of the structural support layer 30 is in the range of 1 µm to 10 µm. Since the layer 30 is subsequently processed to remove material to form openings or cavities in the layer 30 to form different types of structural features, the layer 30 is referred to herein as the structural support layer 30. Preferably, the structural support layer 30 is made of a hard material, preferably a carbon-based hard material, such as diamond-like carbon (DLC), more preferably Ta-C. In this respect, in addition to providing adhesion, the adhesive layer 20 also acts as a damper or transition layer to reduce the adverse mechanical consequences of binding a softer material (e.g., a core or substrate 10, which may be made of steel) to an extremely hard layer (e.g., a structural load-bearing layer 30, which may be molded by DLC). In this respect, the hardness and modulus of the adhesive layer 20 are between those of the core or substrate 10 and those of the structural load-bearing layer 30, thereby preventing cracking of the structural load-bearing layer 30. Through repeatable steps S20, S30, and S40, a multi-layered structure can be deposited instead of a single structural load-bearing layer 30, thus, as... Figure 1B As shown in the cross-sectional view, an external structural support layer 36 and a subsequent mask layer 40 are formed, along with additional DLC layers 32 and 34.

[0023] For example, preferably, deposition step S20 can be performed by a plasma-enhanced PVD (PEPVD) process; thereafter, preferably, step S30 can be performed by a plasma-enhanced CVD (PECVD) process to deposit DLC. Deposition step S30 can be performed by using a rotating device to rotate a cylindrical metal cylinder or core or substrate 10 about its axis of rotation while exposing the cylindrical surface 12 to high-energy plasma. In this regard, preferably, the DLC is fabricated using a CVD process in the same machine (e.g., the same processing cavity) used for the PVD process. The bonding of the structural support layer 30 to the substrate 10 is achieved by an adhesion layer 20 to significantly increase the adhesion between the structural support layer 20 and the metal surface of the substrate 10, since the DLC is not directly bonded to the metal.

[0024] The coating of the adhesion layer 20 in step S20 and the coating of the structural support layer 30 in step S30 may include a homogeneous layer, a stack of chemically or structurally different layers, an internal nanostructure layer, or a combination thereof, in which different phases within the internal nanostructure layer are formed by defined phase separation. These two steps S20 and S30, as well as the subsequent deposition step S40, can also be referred to as a multilayer deposition step S50 because these steps can occur within the same deposition apparatus, sharing the same deposition cavity.

[0025] At this stage of the method, preferably, the outermost cylindrical exposed surface of the treated cylindrical metal core or substrate 10, i.e., the outer surface of the structural support layer 30 or the outer surface of the last layer (outer structural support layer 36) of the multilayer structure, has a very small surface roughness, preferably a surface roughness parameter (RA) of less than 100 nm, more preferably less than 50 nm, and even more preferably less than 10 nm, to achieve excellent optical surface properties. This low roughness is provided by using a cylindrical metal core or substrate 10, which has an even lower surface roughness parameter RA, as described above.

[0026] Next, the method includes depositing a mask layer 40 on a hard coating (e.g., as shown in the image). Figure 1B Above the structural support layer 30 or the external structural support layer 36 shown, the thickness of the mask layer 40 is equal to or less than 100 nm, preferably in the range of 5 nm to 50 nm, more preferably in the range of 5 nm to 20 nm. The material used for the mask layer 40 needs to be suitable for resisting different types of etchants that will be used subsequently to etch openings or cavities within the DLC, such as the structural support layer 30 or the external structural support layer 36. For example, the mask layer 40 can be made of a thin layer of Cr, CrO, Ti, TiO2, or SiO2, preferably made without a substrate or a combination of one or more such layers. Preferably, this step produces a layer of aggregated material, for example, by performing another PECVD or PEPVD step, wherein the mask layer 40 is deposited on top of the structural support layer 30 or the external structural support layer 36 while the roller or substrate 10 is rotated. As another variation, the mask layer 40 can be provided by atomic layer deposition (ALD), for example, for depositing a TiO2 or Al2 mask layer.

[0027] In this paper, the mask layer 40 is not a conventional mask layer made of photoresist or polymer materials, but rather a coating formed through a deposition process similar to that of the structural support layer 30. The mask layer 40 is prepared very thinly and is made from inorganic materials using (PE)PVD deposition. Therefore, preferably, the mask layer 40 is prepared in a deposition step S40, which is performed directly after the deposition step S30 of the structural support layer 30, for example, by using the same deposition apparatus, such as in a vacuum chamber where there is no unnecessary discharge and no unnecessary temperature change between steps S30 and S40. This allows for the provision of a built-in mask layer for the subsequent etching step S120, which has high structural continuity with the structural support layer 30; therefore, the mask layer 40 does not need to be removed for the final embossing device 200.

[0028] Next, as Figure 2B As shown, a laser ablation step S90 or a selective mask removal step S100 / S110 is performed, wherein a portion of the mask layer 40 is removed by performing material removal on the mask layer 40 to form at least one etched opening 45 for etching. The etched opening 45 is formed at multiple locations where, in a subsequent stage of the method, structural embossing features 210, 220, 210a, and 220a are etched into the structural support layer 30 or the outer structural support layer 36 of the roller or substrate 10, 10a by removing material from the structural support layer to form cavities or openings in the regions of the etched opening 45. The laser ablation step S90 can be performed using different types of laser ablation techniques, for example, by using a focused ultraviolet (UV) laser beam with a single Gaussian distribution (S60) or a laser whose distribution is controlled by a spatial light modulator (SLM) to generate multiple focal spots (S80). In this step, in a specific surface area, all material of the mask layer 40 is removed to define one or more etched openings 45 without affecting, or only slightly affecting, the surface of the structural support layer 30 or the external structural support layer 36. Preferably, this can be achieved by using an ultrafast laser source to minimize thermal effects that may occur during the ablation of the mask layer 40, or by using a low-power nanosecond laser, the wavelength and power of which are carefully selected so that the mask layer 40 absorbs most of the laser power while keeping the thermal effects sufficiently low to avoid any drastic changes to the structural support layers 30, 36, which, exemplarily, are made of DLC.

[0029] As an example, the ultrafast laser source used for the laser ablation step S90 can be a laser with a wavelength between 250 nm and 1100 nm, a pulse duration between 100 fs and 10 ps, ​​a frequency between 1 kHz and 10 MHz, and a power between 1 W and 100 W. Laser ablation machines can be used for this task, for example, in U.S. Patent Nos. 9,579,924, 9,993,895, or 2017 / 0066079, the entire contents of which are incorporated herein by reference. Because the mask layer 40 is deposited to have a very small thickness, a relatively low laser power is sufficient to remove it compared to conventional 3D laser ablation. The structural features 210, 220, 210a, 220a at depths DE1, DE2 within the structural support layers 30, 36 are etched by step S120 (e.g., by plasma processing). Etching step S120 is performed after mask ablation steps S60, S100 / S110, or a combination thereof. Figure 2C As shown.

[0030] In a variant, the laser ablation step S90 is configured not only to sufficiently remove the mask layer 40 at the etched opening 45, but also to potentially cause scratching (i.e., slight removal of the top portion of the structural support layers 30, 36), for example, by selecting a stronger laser or by increasing the ablation time. Subsequently, using the subsequent etching step S120, material is removed from the remaining portion of the structural support layers 30, 36 to form surface cavities or openings within the structural support layers 36, 30. These surface cavities or openings form structural features 210, 220, 210a, 220a at the location of the etched opening 45, and these structural features can be used as structural embossing features of the embossing apparatus 200. For this variant, it is preferable that the structural support layers 30, 36 suffer only minimal structural damage or transformation from sp3 carbon due to the heating by the ablation laser in step S90, for example, to avoid or minimize graphite formation and other thermal artifacts on the surface of the DLC, thereby not affecting the etching at the etched opening 45 of the DLC material using step S120. Graphite is chemically resistant to etchants that can remove DLC materials, while thermodynamically, the unstable diamond in DLC can react with oxygen during etching to form, for example, CO2 or various forms of oxycarbon. As described above, the etching process removes material from the exposed area at the etch opening 45 without damaging the material, i.e., without causing structural phase transitions other than those resulting from the removal.

[0031] In one variant, the laser ablation step can also be performed using mask projection technique S70 to selectively ablate a mask layer 40 that has already been masked using a single laser mask at at least one etched opening 45, for example, as shown in U.S. Patents Publications 2012 / 0018993 and 2017 / 0066079 (the entire contents of which are incorporated herein by reference). In the case of using a multilayer coating as described below, ablation steps S60, S100 / S110, or combinations thereof, and etching step S120 can be repeated any number of times at different locations on the surface to create a layered multilayer structure 210, as... Figure 2A and 2B The following discussion further illustrates this point.

[0032] In one variant, material removal on mask layer 40 is not performed by laser ablation, but involves another process to form etched openings 45, such as electron beam structuring S100, or material removal from mask layer 30 by a separate etching step, or by a focused ion beam.

[0033] The etched openings 45 can themselves have various shapes; for example, they can form an array layout having multiple longitudinal openings formed on the surface of the structural support layer 30 (parallel to the central axis CA of the cylinder or roller 10) and multiple transverse openings formed on the surface of the structural support layer 30 in the tangential direction (perpendicular to the central axis CA). This allows the formation of diffraction structures in the structural support layer 30 as structural features 210, 210a, including multiple first grooves at a first angular orientation and multiple second grooves at a second angular orientation (substantially perpendicular to the first angular orientation). As an example, it is possible to form structural features 210, 210a including diffraction structures, wherein the depth of the diffraction structure is between 50 nm and 10 µm, the width of the diffraction structure is between 100 nm and 10 µm, the periodic lines of the diffraction structure are in the range between 0.1 µm and 10 µm, and the ratio between the depth and width of the diffraction structure is in the range between 0.25 and 1.2.

[0034] In one variation, according to another aspect of the invention, a plasma structure can be formed within a substrate or cylindrical base 10 using a method wherein the plasma structure is appropriately modulated, and the shape of the plasma structure is accurate to a few nanometers. In this variation, the hard coating 40 can be directly ablated by an electron beam structuring method without using a structured photoresist / etching combination. The thickness of the ultrathin hard mask layer 40 used for direct photon number ablation is preferably less than 50 nm, more preferably less than 30 nm, and even more preferably in the range of 5 nm to 20 nm.

[0035] In another variant, after performing steps S10-S50, an electron beam writing or structuring step S100 is performed to provide a structured layer 50 of electron beam photoresist on top of a preferably ultrathin, inorganic, non-conductive mask layer 40. In a first intermediate step, the hard mask layer 40 is completely covered with (photo)sensitive photoresist by spin coating, dip coating, spray coating, or other suitable methods to provide a homogeneous, pore-free / pinhole-free photoresist layer. Then, the structural integrity of the photoresist is modified by writing the desired structure into the homogeneous photoresist layer using a highly precise focused electron beam. The photoresist material generally comprises organic and / or polymeric materials provided in liquid form. Next, in the mask development step S105, the thus exposed electron beam photoresist layer 50 is developed and selectively removed using a chemical bath adapted to the chemical properties of the photoresist layer, thereby exposing the mask layer 40. Next, in step S110, the mask layer 40 is etched based on the type of mask layer 40 used, for example by wet etching or dry etching, instead of performing direct ablation of the mask layer 40. The etchant used in step S110 is selected to be non-reactive to the material of the underlying structural support layer 30, thereby removing only the exposed mask layer 40. Steps S105 and S110 in the embodiment described in this paragraph are optional steps. Figure 1A It is shown in the middle with a dashed rectangle.

[0036] Once the mask layer 40 is structured using electron beam technology as described above, the method performs the previously discussed etching step S120, for example, performing a plasma step to etch the rigid material from the structural support layer 30 to form structural features 210, 210a, for example, by using O2 or another type of plasma that can etch DLC material. The resulting embossing roller 200 can then be used to emboss the plasma structure on metal paper or foil. Furthermore, as another example, the embossing apparatus 200 described herein, for example, an embossing cylinder or roller, can be used to fabricate microstructures for rapid replication of microfluidic circuits by thermoplastic thermoembossing of thermoplastic foil or sheet, wherein the etched openings 45 can be the shape of a microfluidic circuit. One advantage of this method is that the embossing roller 200 has already exposed the rigid material, such as DLC, which can improve the release of some thermoplastic material once the structural feature 210 (forming surface cavities) is formed therein. The embossing apparatus 200 described herein can also be used for other applications. For example, the outline of a circuit can be formed by embossing a conductive material (e.g., a metallic material), such as a radio-frequency identification (RFID) antenna, which has previously been engraved as structural feature 210 on a roller. For example, using some special laminate paper with a metallic layer, the roller 200 can be used to emboss the laminate paper to break the metallic layer, thereby replicating the circuit or device.

[0037] Once the material of the mask layer 40 is removed at the multiple etched openings 45 to form the structural embossing feature 210, the etching step S120 at the location of the opening 45 (preferably as shown in the image) is then performed. Figure 2BThe illustrated dry etching step using plasma is used to form the structural embossed features. In step S120, etching is performed to remove material (particularly, the DLC material of the structural support layer 30 or the outer structural support layer 36) at at least one opening of the mask layer 40 to form a surface cavity at the at least one opening. This surface cavity forms a structural embossed feature 210 with a certain depth within the hard coating layer 40, thereby forming a structured embossed cylinder 200. Preferably, the depth of the structural embossed feature 210 is greater than 50 nm and less than 7 µm, more preferably less than 3 µm. Regarding the width of the structural embossed feature 210, the width of one feature 210 can be in the range of 100 nm and 20 µm, more preferably up to 1.5 µm. The etching process in step S120 can be performed by reactive ion etching (RIE) within the etching apparatus 200, for example, oxygen (O2) plasma or CF4 plasma. This can be performed by placing the substrate or roller 10 within the center of the first cage electrode 430 and connecting the (preferably cooled) electrode 420 to a radio frequency (RF) generator (not shown) within the plasma cavity 410 via a thermoelectric connection enabler 421 within the center of the plasma cavity, ensuring that the plasma is uniformly generated between the cage electrode 430 and the substrate or roller 10, as exemplarily shown in the cross-sectional view of FIG4. Furthermore, the mask layer 40 used as the etching mask in step S120 can be removed in a separate or optional step S120, or can be retained on the structural support layer 30 to avoid further processing and save cost and time. During the use of the embossing apparatus 200, the mask layer 40 can be exhausted and gradually worn away. Because the mask layer 40 can be selected to be very thin, its presence has little or no effect on the mechanical properties of the embossing apparatus 200.

[0038] like Figure 2CAs exemplarily shown in the cross-sectional view, this etching using step S120 allows for the creation of steep sidewalls of the structural embossed feature 210 at the edge of the etched opening 45, for example, with the sidewalls having an angle of approximately 90° relative to the upper surface, such as in the range between 75° and 90°. Furthermore, the etching step S120 allows for the provision of a structural embossed feature 210 with a high aspect ratio (ratio between depth and width), in other words, creating a structural embossed feature 210 that is deeper in the axial direction (compared to a smaller width in the tangential or axial direction), for example, but not limited to an aspect ratio in the range of 0.1 to 2 (more preferably 0.25 to 1.2), for example, to create deeper longitudinal grooves, channels, or trenches with such an aspect ratio in any direction within the structural support layer 30. However, it is also possible to create a structural embossed feature 210 with a smaller aspect ratio. Furthermore, considering that the upper surface of the structural support layer 30 is cylindrical or arc-shaped, step S120 allows ensuring that the depth of the structural embossing feature 210 from the upper surface of the structural support layer 30 is substantially the same.

[0039] By using etching step S120 (which can completely replace other laser engraving or ablation steps or can be used in combination with other laser lithography or cleaning techniques), the effects of heating caused by laser ablation on the structural support layer 30 or the external structural support layer 36 (e.g., in the case where the structural support layer 30 or the external structural support layer 36 is made of DLC material) can be significantly reduced or even completely eliminated. In this regard, the heat generated during laser ablation at the location where material is removed from the structural support layer 30 or the external structural support layer 36 to form structural features (e.g., the heat-affected zone, HAZ) may alter the properties of the DLC, resulting in the formation of a softer, sp2-rich material from the original phase of material with a significant proportion of tetrahedral sp3 bonds. For example, see Yasumaru et al., “Glassy carbon layer formed in diamond-like carbon films with femtosecond laser pulses,” Applied Physics A, Vol. 79, No. 3, pp. 425-427, year 2004; and Miyaji et al., “Nanostructuring with Femtosecond Laser Pulses on Patterned DLC Surface,” JLMN-Journals of Laser Micro / Nanoengineering, Vol. 3, No. 2, pp. 84-87, year 2008. (2008). sp3-bonded carbon exhibits diamond-like properties in terms of bonding and hardness, while sp2-bonded carbon, as the primary phase, exhibits graphite-like properties, including significantly reduced hardness and a flake-like morphology. This makes them unsuitable for applications requiring hardness and overall structural integrity, such as microstructures with high aspect ratios, for example, the structural embossing feature 210 described herein. Therefore, the hardness of the structural support layer 30 or the external structural support layer 36 may decrease significantly after simple and direct laser engraving or ablation.Since the structural bearing layer 30 or the external structural bearing layer 36 can be characterized by hardness and structural integrity under mechanical stress, and these properties can be directly derived from its sp3 bonds, the reduction of the portion of sp3 bonds and the increase of the occurrence of sp2 bonds are undesirable for any application of the structural embossing feature 210 and the structured embossing equipment or cylinder 200 (which requires high structural integrity and hardness).

[0040] Furthermore, using deposition step S40 to deposit and provide mask layer 40, and adjusting the ablation parameters for ablation or engraving (when forming etch openings 45 within mask layer 40 using ablation step S90), can minimize the sp2-bonded phase in structural support layer 30 or external structural support layer 36, and can also reduce or minimize other adverse effects on the structural integrity of structural support layer 30 or external structural support layer 36. Obtaining specific depths DE1, DE2 of structural embossing feature 210 by performing a plasma etching process in step S120 avoids the formation of graphite around structural embossing feature 210 from the carbon-based material of structural support layers 30, 36, because the removal of material by reactive etching using, for example but not limited to, oxygen plasma is primarily achieved through chemical reaction rather than thermal decomposition, as this would be the case with direct laser engraving or ablation.

[0041] Furthermore, step S40, which involves depositing the mask layer 40, makes it possible to provide an ultrathin inorganic coating as the mask layer 40. This offers the following advantages: the mask layer 40 can remain on the surface of the unstructured portion of the structural support layer 30 or the external structural support layer 36, for example, in areas where no etched openings 45 appear, and does not need to be specifically removed, unlike conventional polymeric or other organic mask materials. The elimination of additional stripping or cleaning steps to remove the mask layer 40 or another mask different from the mask layer 40 described herein after structuring via etching step S120 significantly reduces processing time, which can be a significant cost reduction factor. It also reduces the environmental impact of the process caused by typical solvents and stripping solutions used for removing conventional organic mask layers. The extremely low thickness of the mask layer 40 ensures that the mechanical properties of the final embossed tool produced by the embossing equipment 200 are not affected when the mask layer 40 remains on the structural support layer 30 or the external structural support layer 36. This extremely low thickness (e.g., in the range of just a few nanometers) further means that contamination of any type of surface caused by wear of the mask layer 40 will be minimal and likely negligible.

[0042] Furthermore, in one variant, multiple rounds of deposition steps S30 (e.g., PECVD deposition steps) for forming the structural support layer 30 and deposition steps S40 (e.g., PEPVD deposition steps) for depositing the mask layer 40 can be performed to create a multilayer structure on top of the adhesion layer 20, the multilayer structure having alternating mask layers and structural support layers, such as... Figure 2A The cross-sectional view shown illustrates an adhesion layer 20, a first internal structural support layer 32 made of a hard material coating, a first internal mask layer 42, a second external structural support layer 36 made of a hard material, and a second external mask layer 46. This multi-layered structure allows for the formation of multiple layers of three-dimensional openings or structural features 210 within the embossing apparatus 200 through successive mask removal steps S90, S100 / S110 or combinations thereof (for removing portions of mask layers 46, 42 respectively) and an etching step S120 (for removing material from structural support layers 36, 32). In other words, this allows for the formation of etched openings 45, 47 respectively using successive laser removal steps S90 (for removing some mask portions of mask layers 46, 42) and etching steps S120 (for removing portions of structural support layers 36, 32), as shown in the image. Figure 2B As shown. In this variant shown, two (2) mask layers 42, 46 and two (2) structural support layers 32, 36 are shown alternating, but more than two (2) such layers may be present to provide more complex multilayer structural features 210, such as three, four, five or more pairs of mask and structural support layers. For example, multilayer structural features 210 may be used to form complex three-dimensional (3D) shapes as openings or cavities in the surface of embossing equipment 200, for example, as injection molds with cavities for different types of casting processes. In the case of multiple mask layers / DLC stacks, it is not indicated that the outermost mask layer on the outermost DLC layer will be made of a material with predominantly non-metallic characteristics, such as nitrides, oxides or carbides, to ensure adhesion of the following DLC ​​layers.

[0043] Figure 2BA multilayer structural feature 210 formed within an embossing apparatus 200 is illustrated. Each structure 210 is formed from a wider first structure 210.1 within an outer structural support layer 36, an external etched opening 45 in an outer mask layer 46, a narrower second inner structure 210.2 within an inner structural support layer 32, and an internal etched opening 47 in the inner mask layer 42. To form the multilayer structural feature 210, a first laser etching step S90 is performed to remove the etched opening 45 at a desired location in the outer mask layer 46. Subsequently, a first etching step S120 is performed to remove material from the outer structural support layer 36 to form the wider structure 210.1, up to the upper surface of the inner mask layer 42. Next, a second laser etching step S90 is performed to remove the etched opening 47 at a desired location in the inner mask layer 42. Preferably, the etched opening 47 is smaller on the surface, for example, narrower and / or shorter, compared to the opening formed by the wider structure 210.1. Subsequently, a second etching step S120 is performed to remove the material of the internal structural support layer 32 to form a narrower structure 210.2. This step can be performed selectively, such that the narrower structure 210.2 does not reach the upper surface of the adhesion layer 20 in the radial direction, such as... Figure 2B As shown. If more mask layer-structure bearing layer pairs exist, steps S90, S100 / S110 or combinations thereof and S120 can be repeated more often to form additional structural features in the radial direction of the embossing device 200.

[0044] According to another aspect of the invention, an apparatus preferably prepared by the method described herein is provided, based on the apparatus or cylinder 200 described herein, which is a mold-type apparatus, such as an injection mold and a cylindrical mold for casting demolding or thermoplastic hot embossing. In this variant, one or more mold cavities may be formed by structural embossing features 210.

[0045] According to at least some aspects of the present invention, the method for preparing embossing equipment 200 (e.g., embossing cylinder, roller, or roll) and the corresponding embossing equipment 200 described herein offer several advantages over the prior art, in which hard coatings are directly ablated to form structural features in the hard coating, for example, by using nanosecond or ultrafast lasers. Efficient direct laser processing is always accompanied by the presence of a heat-affected zone (HAZ). For nanosecond lasers, HAZ diffusion is crucial. While HAZ is reduced somewhat by ultrafast, picosecond, and femtosecond lasers, it still exists and is a factor to consider. Some hard coatings (particularly DLC, such as Ta-C variants) are thermally sensitive because excessive heating and oxygen bonding can cause the carbon lattice to transform from a diamond-like structure to a weaker structure. Therefore, the processing of DLC requires a substantially non-thermal process, wherein no heating to the temperature required to induce a structural phase transition in the material of the structural bearing layer under the environmental conditions in which the processing occurs.

[0046] According to some aspects of the invention, laser ablation is performed using step S90 to create etched openings 45, 47 using low energy, which will only affect the mask layers 40, 42 and not the underlying structural support layers 30, 32, and 36. The actual engraving or material removal performed on the structural support layers 30, 32, and 36 to form the structural feature 210 is performed via etching in one or more steps S120, which does not involve sustained overheating, and the integrity of the DLC lattice remains intact. Therefore, the physical properties of the hard coating forming the structural support layers 30, 32, and 36 remain unchanged.

[0047] According to some aspects of the invention, the laser ablation step S90 is performed in a single pass to remove portions of the mask layers 40, 42, and 46. The depth engraving or material removal by the etching step S120 is performed simultaneously across the entire surface in a single step, for example, using a plasma etching apparatus. This means that for large devices, the engraving or material removal time corresponding to the duration of one or more etching steps S120 can be significantly reduced compared to processes where engraving or material removal is accomplished by laser ablation or laser material removal, where multiple passes are required in the same location to achieve the desired structural depth within the structural support layers 30, 32, and 36. Furthermore, the structural engraving performed by plasma etching in step S120 allows for very fine control over the etching depths DE1, DE2, and results in very large aspect ratio structures due to the anisotropic etching of the hard layers.

[0048] While the invention has been disclosed with reference to certain preferred embodiments, many modifications, substitutions, and alterations can be made to the described embodiments without departing from the field and scope of the invention as defined in the appended claims and their equivalents. Therefore, it is intended that the invention be limited to the described embodiments but has the full scope defined by the language of the following claims.

Claims

1. A method for manufacturing a structured embossing cylinder for an embossing system, comprising the following steps: A hard-coated embossing roller with a cylindrical core is provided. An adhesion layer is provided on the cylindrical core by a first plasma-enhanced vapor deposition in a vacuum chamber. The thickness of the adhesion layer is in the range of 100 nm to 200 nm, and the hardness of the adhesion layer is greater than the hardness of the outer surface of the cylindrical core. A structural support layer is formed on the adhesion layer by a second plasma-enhanced vapor deposition in a vacuum chamber. The thickness of the structural support layer is in the range of 1 µm to 10 µm, and the surface roughness Ra of the structural support layer is less than 100 nm. A hard mask layer is deposited on the structural support layer by a third plasma-enhanced vapor deposition method, the thickness of the hard mask layer being equal to or less than 100 nm. Material is removed from the hard mask layer to form at least one opening; as well as Etching is performed to remove material from the structural support layer at at least one opening in the hard mask layer to form a surface cavity in the structural support layer at the at least one opening. The surface cavity forms a structural embossing feature within the structural support layer, thereby forming the structured embossed cylinder. The material of the hard mask layer held on the surface of the unstructured portion of the structural support layer is not removed after the etching step.

2. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 1, wherein, The structural support layer comprises diamond-like carbon (DLC) deposited by plasma-enhanced chemical vapor deposition.

3. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 1, wherein, The thickness of the hard mask layer is greater than 5 nm and less than 50 nm.

4. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 1, wherein, The hard mask layer comprises inorganic materials.

5. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 1, wherein, The step of removing material from the hard mask layer is performed by laser ablation.

6. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 1, wherein, The process of removing material from the hard mask layer is performed by electron beam structuring.

7. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 5, wherein, The step of performing the laser ablation on the hard mask layer includes using direct laser ablation, using mask projection of a laser beam, or using a spatial light modulator (SLM) to shape the laser beam.

8. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 6, wherein, In the step of performing the electron beam structuring, the thickness of the hard mask layer is equal to or less than 50 nm.

9. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 1, wherein, The etching step for the structural support layer includes plasma-assisted reactive ion etching.

10. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 1, wherein, The etching step includes wet etching.

11. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 1, wherein, The depth of the surface cavity formed in the etching step is greater than 50 nm and less than 7 µm.

12. The method for manufacturing a structured embossing cylinder for an embossing system according to claim 1, wherein, The first plasma-enhanced vapor deposition, the second plasma-enhanced vapor deposition, and the third plasma-enhanced vapor deposition are sequentially processed in the vacuum chamber.

13. A method for manufacturing a structured embossing cylinder for an embossing system, comprising the following steps: A hard-coated embossing roller with a cylindrical core is provided. An adhesion layer is provided on the cylindrical core by a first plasma-enhanced vapor deposition in a vacuum chamber. The thickness of the adhesion layer is in the range of 100 nm to 200 nm, and the hardness of the adhesion layer is greater than the hardness of the outer surface of the cylindrical core. A structural support layer is formed on the adhesion layer by a second plasma-enhanced vapor deposition in a vacuum chamber. The thickness of the structural support layer is in the range of 1 µm to 10 µm, and the surface roughness Ra of the structural support layer is less than 100 nm. A hard mask layer is deposited on the structural support layer by a third plasma-enhanced vapor deposition method, the thickness of the hard mask layer being equal to or less than 100 nm. Electron beam writing is performed on the electron beam photoresist layer provided on top of the hard mask layer; The electron beam photoresist layer is developed and removed to expose the hard mask layer; The hard mask layer is etched using an etchant that does not affect the structural support layer. as well as The structural support layer is etched to form a surface cavity within the structural support layer, the surface cavity forming a structural embossing feature within the structural support layer, wherein the material of the hard mask layer held on the surface of the unstructured portion of the structural support layer is not removed after the etching step.

14. A structured embossing device, comprising: Base; The adhesive layer on the substrate has a thickness in the range of 100 nm to 200 nm, and the hardness of the adhesive layer is greater than the hardness of the outer surface of the substrate. The structural support layer on the adhesion layer has a thickness in the range of 1 µm to 10 µm and a roughness value Ra of the structural support layer is less than 100 nm. An inorganic hard mask layer on the structural support layer, wherein the thickness of the inorganic hard mask layer is less than 100 nm; and An embossed structure disposed on the surface of the structural support layer, the embossed structure passing through the hard mask layer. The depth of the surface cavity formed by the embossed structure is between 50 nm and 7 µm, and the width of the surface cavity is between 100 nm and 10 µm. The final structured embossing device includes the inorganic hard mask layer, which is resistant to etchants used to etch the structural support layer.

15. The structured embossing equipment according to claim 14, wherein, The ratio between the depth and the width of the cavity is in the range of 0.1 to 2.

16. The structured embossing equipment according to claim 14, wherein, The substrate includes a cylinder made of metal, ceramic, or composite material.

17. The structured embossing equipment according to claim 14, wherein, The substrate includes a plate made of metal, ceramic, or composite material.

18. The structured embossing equipment according to claim 14, wherein, The surface cavity forming the embossed structure is in the form of a groove.

19. The structured embossing equipment according to claim 14, wherein, The surface cavity forming the embossed structure includes a diffraction grating.

20. An injection mold, comprising: Base; The adhesive layer on the substrate has a thickness in the range of 100 nm to 200 nm, and the hardness of the adhesive layer is greater than the hardness of the outer surface of the substrate. The structural support layer on the adhesion layer has a thickness in the range of 1 µm to 10 µm and a roughness value Ra of the structural support layer is less than 100 nm. An inorganic hard mask layer on the structural support layer, wherein the thickness of the inorganic hard mask layer is less than 100 nm; and A mold cavity disposed in the surface of the structural support layer, the mold cavity passing through the hard mask layer. The depth of the surface opening formed by the mold cavity is between 50 nm and 7 µm, and the width of the surface opening is between 100 nm and 10 µm. The final injection mold includes the inorganic hard mask layer, which is resistant to etchants used to etch the structural support layer.

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