Structured substrate, method for manufacturing a structured substrate, and use of the structured substrate

Abstract

The present invention relates to a structured substrate (1), preferably for use in microsystems technology such as micro-optical systems, comprising a flat substrate (10) preferably comprising a glass material and having two opposing flat surfaces (12, 14); at least one through hole (20) extending through the material of the flat substrate (10) to form an inner wall surface surrounding the through hole (20) and connecting the two opposing flat surfaces (12, 14); and a light-absorbing and / or light-reflecting coating (30) covering at least some area of ​​the inner wall surface of the through hole (20), wherein one or both of the flat surfaces (12, 14) is free of the coating (30). The inner wall surface has an arithmetic mean roughness between 0.2 micrometers and 2 micrometers, and / or the coating (30) has an arithmetic mean roughness between 0.05 micrometers and 2 micrometers. The present invention further relates to a method for manufacturing the structured substrate and uses of the structured substrate.

Description

[Technical Field]

[0001] The present invention preferably relates to structured substrates for applications in microsystems technology, such as micro-optical systems.

[0002] In microsystems technology, for example, to manufacture micro-optical systems, multiple wafers or substrates are often stacked on top of each other to form a layered system. At the wafer level, hundreds of optical devices are typically fabricated on each wafer. For complex optical systems, such as imaging optics for smartphones, several such functional wafers are combined in a layered system. Thus, a single device is obtained during the dicing step. Such layered systems often also include a spacer wafer or spacer substrate to achieve a desired distance between functional layers containing optical elements. Such a spacer wafer is a flat glass wafer of a specified thickness with numerous through-holes, which have at least the diameter of the individual optical elements of the functional wafer. However, depending on the surface of the through-holes, undesirable reflections, reduced contrast, ghosting, or other disturbances may occur in the final device.

[0003] When manufacturing such microsystems, the alignment of multiple wafers or substrates relative to one another is crucial to ensure the functionality of the micro-optical devices. For such alignment of wafers or substrates, printed or ablated surface markings are often used. However, such near-surface markings can have the disadvantage of potential parallax errors. Another option is to use through-holes in the wafer or substrate as alignment marks or fiducials. However, pattern recognition of such through-holes is problematic due to the low contrast of the through-hole markers. Misalignment of lenses relative to one another is detrimental to imaging performance. The more compact the micro-optical system, for example, using high-index lenses, the tighter the tolerances.

[0004] It is therefore an object of the present invention to optimize the assembly of microsystems by reducing stray light, reflections, ghosts or other disturbances in spacer substrates in layered micro-optical systems, increasing contrast and improving pattern recognition, especially of through-holes.

[0005] To solve this object, a structured substrate, preferably for application in microsystems technology, such as micro-optical systems, is disclosed as defined in claim 1.

[0006] The structured substrate comprises a flat substrate having two opposing flat surfaces, which may comprise a brittle material such as, for example, glass, ceramic, glass-ceramic, etc., as described in more detail below.

[0007] The structured substrate further comprises at least one through hole extending through the material of the planar substrate forming an interior wall surface surrounding the through hole and connecting two opposing planar surfaces.

[0008] Additionally, the structured substrate includes a coating covering at least some areas of the inner wall surfaces of the through holes, the coating being light absorbing and / or light reflective.

[0009] For use in alignment, vertical or near-vertical walls are preferred. Thus, in some embodiments of the invention, the angle of the inner wall surface relative to the flat surface may be 90° + / - 1°, preferably + / - 0.5°, more preferably + / - 0.25°.

[0010] However, for other applications, such as beam traps, a conical design may be employed. Thus, in some embodiments of the present invention, at least one through-hole is conical, such that the diameter of the at least one through-hole decreases or increases from one flat surface of the substrate to the other flat surface. The preferred angle of the conical shape is in the range of 0°, 5° to 15°, more preferably 1° to 12°, even more preferably 2° to 10°, and most preferably 4° to 8°. The angle refers to the angle of the inner wall relative to the normal to the plane defined by the flat surface of the substrate.

[0011] Furthermore, the at least one through hole may have an hourglass shape such that the diameter of the at least one through hole decreases from each of the flat surfaces toward a central portion having a smallest diameter. Each of the two conical sections of the hourglass shape may have an angle in the range of 0.5° to 15°, more preferably 1° to 12°, even more preferably 2° to 10°, and most preferably 4° to 8°. The two conical sections of the hourglass shape may have the same angle. Alternatively, different angles are selected for each of the two conical sections.

[0012] Preferably, the angle of the central axis of at least one through-hole relative to the flat surface of the substrate is perpendicular to the flat surface, whereby the angle of the central axis of the through-hole relative to the flat surface may be 90° + / - 1°, preferably + / - 0.5°, and more preferably + / - 0.25°. Alternatively, the through-holes may be configured to be angled relative to a normal defined by the flat surface of the substrate, whereby the angle of the central axis of the through-hole relative to the normal defined by the flat surface may be greater than 0° and up to 15°, preferably 1° to 12°, and more preferably 5° to 10°. For example, a through-hole array used to suppress stray light incident on an X-ray detector can consist of an array of holes, with each row or set of rows of through-holes having a different inclination toward the surface normal; for example, the arrangement may include five rows of 0° holes, five rows of 1° holes, and further sets of rows until a final set of five rows of 10° holes is reached. Such a filter thus represents a fan-shaped collection of through-holes.

[0013] In general, the flat substrate may have any thickness, i.e., the dimension extending from one flat surface to the other, which is between 20 μm and 8 mm, preferably between 50 μm and 4 mm, more preferably between 100 μm and 3 mm, and most preferably between 250 μm and 1 mm.

[0014] A through hole extending through the material of the planar substrate may preferably define a diameter that is the smallest dimension of the through hole parallel to the plane of the planar substrate.

[0015] In some embodiments of the present invention, the through-holes may have a diameter between 0.3 μm and 10 mm. Such diameters, diameters in the range of 5 μm to 10 mm, or larger diameters in the mm range may be preferred, for example, for optical cavities, e.g., to reduce stray light in micro-optical systems.

[0016] In some embodiments of the present invention, the through-holes may have a diameter between 0.3 μm and 300 μm. Such a diameter may be preferred for alignment purposes and may preferably be selected so that the structures used for alignment completely fill the field of view of the microscope optics (e.g., up to about 300 μm).

[0017] The aspect ratio may be defined as the ratio between the diameter of the through-hole and the thickness of the planar substrate.

[0018] Such an aspect ratio may be, for example, between 0.000075 and 17.5, preferably between 0.0001 and 10, more preferably between 0.00015 and 5, more preferably between 0.0003 and 2, and more preferably between 0.001 and 1.

[0019] The inner wall surface of the through-hole before coating may also be taken into consideration. It may be preferable for such roughness to be within the range of the wavelength of the light used, for example, in the UV range, VIS range, or NIR range.

[0020] In some embodiments of the present invention, the inner wall surface has an arithmetic mean roughness of between 0.1 μm and 2 μm, preferably between 0.2 μm and 1 μm, and more preferably between 0.4 μm and 1 μm.

[0021] The roughness of the through-hole after coating, i.e., the roughness of the coating itself, may also be considered. Note that the roughness before and after coating may depend on the coating technique and parameters. For example, in the case of atomic layer deposition (ALD), the surface roughness may be maintained, especially when an extremely thin ALD layer is deposited. For example, in the case of a thick layer having a thickness of more than 250 nm or by other coating techniques, the original roughness of the inner wall may be reduced.

[0022] In some embodiments of the present invention, the coating may have an arithmetic mean roughness between 0.05 μm and 2 μm, preferably between 0.1 μm and 1 μm, and more preferably between 0.2 μm and 0.5 μm.

[0023] The coating may have a thickness between 5 nm and 5 μm, preferably between 15 nm and 1000 nm, more preferably between 50 nm and 500 nm.

[0024] Generally, the inner walls of the through-holes may be completely or partially coated.

[0025] In some embodiments of the present invention, the coating covers at least 10%, preferably at least 50%, more preferably at least 90%, and most preferably the entire area of ​​the interior wall surface.

[0026] In some embodiments of the present invention, the inner wall surface is partially free of the coating, in particular at least 10% free along the thickness of the substrate.

[0027] One or both of the planar surfaces of the substrate may be free of a coating.

[0028] One or both of the flat surfaces may be polished. In some embodiments, one or both of the flat surfaces may have an RMS roughness of less than 10 nm, preferably less than 5 nm, more preferably less than 1 nm, more preferably less than 0.5 nm, more preferably less than 0.1 nm. Such surface roughness can advantageously be achieved without additional effort by polishing one or more surfaces. Such low roughness can be achieved by: This can be particularly beneficial when stacking substrates together to form layered systems, thus optimizing the layer bonding step in manufacturing. Lower RMS roughness can result in better contact bonding, sprue manufacturing tolerances, and / or optics manufacturing tolerances.

[0029] Preferably, the flatness of the substrate (total thickness variation (TTV)) is less than 20 μm, more preferably less than 10, most preferably less than 5 μm.

[0030] If the coating is configured to be light absorbing, the parameter of interest may be the absorption or extinction coefficient of the coating.

[0031] In some embodiments of the invention, the coating may have an absorption coefficient α and / or extinction coefficient κ of at least 0.01, preferably at least 0.05, more preferably at least 0.1 for at least one wavelength λ in the range of 250 nm to 1600 nm, preferably in the range of 400 nm to 750 nm, and more preferably for all wavelengths within one of said ranges.

[0032] The complex refractive index is

number

[0033] In some embodiments of the present invention, the coating may have an absorption and / or extinction coefficient for at least one wavelength in the range of 250 nm to 1600 nm, preferably 400 nm to 750 nm, and more preferably all wavelengths within one of said ranges, such that an attenuation of 20 dB is achieved across the thickness of the flat substrate.

[0034] The absorption or extinction coefficients defined above may be preferred for alignment purposes, for example in VIS spectra.

[0035] In some embodiments of the present invention, the coating may be configured to be light reflective specifically for a given design wavelength or wavelength range. In such configurations, the coating may have a reflectivity of greater than 60%, preferably greater than 80%, more preferably greater than 90%, particularly preferably greater than 95%, and even more preferably greater than 99%, and most preferably greater than 99.9%. The absorbent and / or reflective coating may be, for example, in the UV-NIR spectrum.

[0036] When a coating is configured to be primarily light reflective, it is preferred that the coating have no or only little light absorption, particularly for a given design wavelength or wavelength range. Preferably, the light absorption of the reflective coating is less than 3%, more preferably less than 1%, even more preferably less than 0.1%, and most preferably less than 0.001%.

[0037] Similarly, when a coating is configured to be primarily light absorbing, it is preferred that the coating have no or only a small amount of light reflectance, particularly for a given design wavelength or range of wavelengths. Preferably, the light reflectance of the light absorbing coating is less than 3%, more preferably less than 1%, even more preferably less than 0.1%, and most preferably less than 0.001%.

[0038] The design wavelength range is, for example, the range of 250 nm to 1600 nm, or the visible light range of 400 nm to 750 nm.

[0039] Coatings may generally comprise or consist of metals, metal nitrides, metal carbides, or metal oxides. In some cases, metallic materials are preferred, followed by metal nitrides and metal carbides. Note that materials may be selected to be compatible with the process as outlined below.

[0040] In some embodiments of the present invention, the coating is made of any of the following materials: Al2O3, B2O3, Co2O3, Cr2O3, CuO, Fe2O3, Ga2O3, HfO2, In2O3, MgO, Nb2O5, NiO, Pd, Pt, Al, Ag, Mo, W, SiO2, SnO2, Ta2O5, TiO2, TaNx, (Ta,Al)N, TiCrOx, (Ti,Al)N, (Ti,Al)C, TiC, AlC, AlN, TiN, VO2, WO3, ZnO, (Al,Zn)O, ZnS, ZnSe, ZrO2, rare earth (RE) oxides, Sc2O3, Y2O3, carbon, carbon black, Ca 10 The compound may include at least one of (PO4)6(OH)2), polyimide, PMDA-ODA, PMDA-DAH, and 3-aminopropyltrimethoxysilane coupling agent.

[0041] The coating may be configured as a multi-layer structure comprising several layers. A particular example is a coating configured to be reflective, which may be configured as a dielectric mirror comprising multiple alternating layers with different refractive indices.

[0042] As previously discussed, the coating may be applied by one or more of several processes. For example, the light-absorbing coating may be deposited by vacuum deposition, preferably physical vapor deposition (PVD) or chemical vapor deposition (CVD), preferably atomic layer deposition (ALD) or plasma-enhanced chemical vapor deposition (PECVD).

[0043] As mentioned above, the flat substrate may comprise or consist of glass, fused silica, ceramic, glass-ceramic, and / or crystalline, such as sapphire. For example, Zerodur® may be employed. In certain embodiments, polymeric or plastic materials may be used.

[0044] In a preferred embodiment, the flat substrate comprises a glass material, a ceramic material, a glass-ceramic material and / or a crystalline material, for example sapphire.

[0045] The flat substrate may comprise at least one of the following components: an SiO2 content of at least 30 wt%, preferably at least 50 wt%, more preferably at least 80 wt%.

[0046] In a further embodiment of the present invention, the structured substrate may comprise a plurality of through holes extending through the material of the planar substrate, each forming an inner wall surface surrounding a respective through hole and connecting two opposing planar surfaces of the planar substrate.

[0047] In such a plurality of through-holes, each of the through-holes can have the same configuration. Alternatively, all or groups of two or more through-holes can have different configurations, e.g., varying interior wall angle, central axis angle, through-hole diameter, or two or more of the foregoing parameters. For example, the central axis angle can vary from one through-hole to an adjacent through-hole to create a fan-like arrangement of through-holes.

[0048] In some uses of structured substrates, such as spatial light filter elements, the structured substrate may comprise an array of through-holes. In such configurations, the identical through-holes are preferably arranged in a regular two-dimensional grid pattern. Such a pattern can be configured as a square or rectangular arrangement with row and column structures with equal distances between the rows and columns. Other configurations include triangular or hexagonal patterns.

[0049] The distance between two rows and / or two columns is selected, for example, in the range of 2 μm to 1 mm, preferably 20 μm to 400 μm, more preferably 100 to 300 μm. Preferably, the distance or pitch P between two adjacent through-holes is selected with respect to the diameter W of the through-holes on the flat surface so that the pitch P is greater than the diameter W, preferably the pitch is selected so that P>1.1W, more preferably P>1.5W, most preferably P>2W.

[0050] An exemplary application of such a spatial filter element is as a stray light filter in, for example, an X-ray detector. In such spatial filter applications, the coating properties are preferably selected so that the coating is light absorbing and has no or negligible amount of reflection.

[0051] At least one through-hole, or at least one of the plurality of through-holes, may have a cross-section that is non-mirror symmetrical and / or non-circular, preferably including one or more rectangular portions, for example, L-shaped.

[0052] Such a shape may be preferable for aligning the substrate. Generally, the at least one or more through-holes may be designed so that (i) displacement is detectable, (ii) rotation is detectable, and / or (iii) incorrect orientation (top surface of the top surface versus bottom surface of the top surface) is detectable. In particular, the number, size, and / or shape of the at least one or more through-holes may be designed to ensure these conditions. One example is an L-shaped through-hole. However, many other designs are also suitable.

[0053] The present invention also relates to a method for manufacturing a structured substrate, preferably as outlined above.

[0054] The method preferably includes providing a flat substrate comprising a glass material and having two opposing flat surfaces, with at least one through hole inserted or extending through the material of the flat substrate to form an interior wall surface surrounding the through hole and connecting the two opposing flat surfaces.

[0055] The method also includes depositing a light-absorbing and / or light-reflecting coating on the planar substrate that covers at least some area of ​​the interior wall surface of the through-hole.

[0056] The method may also include treating, preferably polishing, one or both flat surfaces of the flat substrate to remove any coating covering the flat surfaces so that the flat surfaces are free of the coating. Polishing may be performed to achieve an RMS roughness of less than 10 nm, preferably less than 5 nm, and more preferably less than 1 nm. For more information on polishing, see pages 319-352 of Chapter 8, "Novel Polishing Methods," in Materials Science and Technology of Optical Fabrication, by John Wiley & Sons et al. (October 16, 2018).

[0057] The method may include inserting at least one through-hole into a planar substrate material. In particular, at least one thin filament or filament-like damage may be introduced into the substrate material by a laser process. Such a filament may have a diameter of approximately 0.1-0.5 μm, e.g., 0.3 μm. Preferably, in a further step, such a filament may then be expanded by etching. Furthermore, multiple filaments may be introduced. By placing multiple filaments close to each other, through-holes of virtually any shape and size can be created. Note that if only small through-holes are desired, etching may be omitted.

[0058] When the structured substrate comprises two or more through-holes, the relative position accuracy of two adjacent through-holes with respect to the center of said through-hole is preferably better than 2%, more preferably better than 1%, and most preferably better than 0.1%. Absolute position accuracy is preferably within + / - 0.5 μm. When using regular patterns such as row and column patterns, the average deviation from a set pitch is preferably less than 0.2 μm, preferably less than 0.02 μm.

[0059] Such high precision may be achieved, for example, by the proposed combined laser and etching method described herein.

[0060] With regard to the method of coating, in some embodiments of the present invention, the light-absorbing and / or light-reflecting coating may be deposited on a flat substrate by vacuum deposition, preferably physical vapor deposition (PVD) or chemical vapor deposition (CVD), preferably atomic layer deposition (ALD) or plasma-enhanced chemical vapor deposition (PECVD).

[0061] The present invention further relates to the use of a structured substrate, preferably as outlined above, for aligning the structured substrate relative to another element, preferably wherein the structured substrate is observed from above on one of its flat surfaces and the coating covering the inner wall surface is viewed from the side to form a contour surrounding the through hole, and preferably the position of said contour surrounding the through hole is compared with a defined position on the other element.

[0062] Such defined locations may be, for example, markings on another wafer comprising functional elements such as micro-optics, optical sensors or emitters.

[0063] It should be noted that observation on top of one of its flat surfaces does not have to be performed directly on the surface, but can be performed through other substrates or layers, in particular a microsystem comprising multiple layers.

[0064] In one particular embodiment, the other element may be a second structured substrate, preferably as outlined above, where the structured substrate and the second structured substrate are positioned on top of each other such that one flat surface of the structured substrate faces one flat surface of the second structured substrate, and both the structured substrate and the second structured substrate are observed from above such that an outline surrounding the through hole of the structured substrate and a second outline surrounding the through hole of the second structured substrate are simultaneously formed, and the position of the outlines is compared with the position of the second outline.

[0065] In use of a structured substrate, the position error between the contour surrounding the through hole and the defined position on other elements, preferably in the xy plane, may be reduced to less than 2 μm, preferably less than 0.1 μm, and even more preferably less than 50 nm.

[0066] Furthermore, the position error between the contour surrounding the through hole and the defined position on other elements, preferably in the z-direction, and more preferably across the entire area of ​​the substrate, may be reduced to less than 20 μm.

[0067] The structured substrate and / or other elements may also be provided with markings introduced by ion beam processing, said markings preferably being used to align and / or assist in aligning the structured substrate relative to another element.

[0068] The invention further relates to the use of a structured substrate as outlined above for manufacturing a microsystem, preferably a micro-optical system.

[0069] Preferably, the micro-optical system comprises a plurality of layers, at least one of said layers being formed as a structured substrate.

[0070] For example, three layers may be stacked, with the middle layer being a structured substrate as outlined above. Such a middle layer may in particular be a spacer layer. Other layers, or outer layers, may be provided with refractive or diffractive micro-optics. In this example, the two outer micro-optic layers and the inner spacer layer are preferably aligned with each other as outlined above.

[0071] Preferably, stray light in the microsystem is reduced by a coating, in particular a light-absorbing and anti-reflective coating, covering the inner wall surfaces of the through-holes extending through the planar substrate material of the structured substrate.

[0072] The invention further relates to an assembly comprising a layer structure of two or more layers, at least one of the layers being a structured substrate as outlined above.

[0073] The assembly may comprise at least one further substrate layer having markings corresponding to the through holes of the structured substrate, the markings of the further substrate and the through holes of the structured layer preferably being aligned as outlined above.

[0074] The assembly may comprise at least three layers, in that order: a first micro-optical layer, a structured substrate as outlined above, and a second micro-optical layer.

[0075] Three such layers may be considered to form a unit cell, and more than three layers, e.g., five layers, may also be stacked with two such unit cells, with the intermediate layer belonging to both unit cells.

[0076] The invention further relates to a beam trap comprising a structured substrate as described above and a further substrate connected thereto, said further substrate comprising at least one blackened and / or roughened surface.

[0077] In general, the present invention is at least suitable for wafer bonding, laminated transparent components, micro-optics, wafer level alignment, stray light suppression, glass circuit boards, microsensors such as wafer level or pressure sensors, microfluidics, LIDAR sensors, sensor arrays, wafer level packaging.

[0078] The invention will be explained in more detail below with reference to the drawings. [Brief explanation of the drawings]

[0079] [Figure 1(a)] FIG. 1 is a side view of processing step (a) for fabricating a structured substrate. [Figure 1(b)] FIG. 1B is a side view of processing step (b) for fabricating a structured substrate. [Figure 1(c)] FIG. 1C is a side view of processing step (c) for fabricating a structured substrate. [Figure 1(d)] FIG. 10 is a side view of processing step (d) for fabricating a structured substrate. [Figure 2(a)] FIG. 2 is a side view of two stacked structured substrates. [Figure 2(b)] FIG. 10 is another side view of two stacked structured substrates illuminated. [Figure 2(c)] FIG. 2 is a top view of two stacked structured substrates. [Figure 3] FIG. 1 is a top view of a substrate having an L-shaped through-hole. [Figure 4] FIG. 10 is a diagram illustrating the alignment of two L-shaped through-holes relative to each other. [Figure 5(a)] FIG. 1 is a side view of processing step (a) for manufacturing a layered assembly comprising a structured substrate and an optical substrate. [Figure 5(b)] FIG. 1B is a side view of processing step (b) for manufacturing a layered assembly comprising a structured substrate and an optical substrate. [Figure 5(c)] FIG. 1C is a side view of processing step (c) for manufacturing a layered assembly comprising a structured substrate and an optical substrate. [Figure 5(d)]FIG. 10 is a side view of processing step (d) for manufacturing a layered assembly comprising a structured substrate and an optical substrate. [Figure 6] FIG. 1 is a side view of a structured substrate having holes arranged in a fan shape. [Figure 7] FIG. 1 is a perspective view of a structured substrate having a plurality of through holes arranged in a regular pattern. [Figure 8] FIG. 1 is a perspective view of a cut structured substrate having a plurality of through holes arranged in a regular pattern. [Figure 9] FIG. 1 is a side view of a structured substrate having a plurality of hourglass-shaped through holes.

[0080] FIG. 1 shows an example of a process for manufacturing a structured substrate 1, which includes steps (a) to (d).

[0081] In step (a), a flat substrate 10 is provided, the flat substrate comprising two opposing flat surfaces 12, 14 and a plurality of through holes 20, 20' extending through a thickness t of the flat substrate.

[0082] Some through-holes 20 have a larger diameter d than other through-holes 20′. The through-holes 20 with the larger diameter d may be designed to accommodate optical elements 62 (see FIG. 5), while the through-holes 20′ with the smaller diameter d may be used to align multiple substrates that are stacked on top of each other.

[0083] In step (b), a light-absorbing and / or light-reflecting coating 30 is deposited on the flat substrate to cover at least some of the inner wall surfaces of the through-holes 20, 20′. Such a coating may have a thickness of, for example, between 5 nm and 5 μm and may be configured to absorb and / or reflect a specific wavelength range, such as the UV-NIR range. The coating may be applied, for example, by atomic layer deposition (ALD), although other coating techniques, such as ion beam coating or liquid coating, are also possible. In this particular example, the light-absorbing and / or light-reflecting coating 30 not only covers the inner wall surfaces of the through-holes 20, 20′, but also covers the two opposing flat surfaces 12, 14 of the substrate 10.

[0084] Therefore, in step (c), the flat surfaces 12, 14 of the substrate 10 are polished to remove any coatings covering the flat surfaces 12, 14, thereby ensuring that the flat surfaces 12, 14 are free of light-absorbing and / or light-reflecting coatings. Polishing can be performed using a polishing medium 40. Plasma etching or laser ablation of the flat surfaces 12, 14 may also be performed to remove any coatings covering the flat surfaces 12, 14. Polishing can also consist of multiple polishing steps, especially when used to improve the surface quality of the flat surfaces. By reducing the grain size, it is possible to obtain RMS roughness values ​​of less than 1 nm, or even less than 0.1 nm. Furthermore, polishing can be used to compensate for the total thickness variation (TTV) of the wafer.

[0085] The resulting structured substrate 1 shown in (d) comprises a flat substrate 10 having a plurality of through holes 20, 20' extending through the material of the flat substrate 10 forming inner wall surfaces surrounding the through holes 20, 20' and connecting the two opposing flat surfaces 12, 14, and a light-absorbing and / or light-reflecting coating 30 covering the inner wall surfaces of the through holes 20, 20'.

[0086] 2(a) shows two laminated structured substrates 1, 1', where the upper substrate 1 has two adjacent through holes 20 with a larger diameter, and the lower substrate 1' has two adjacent through holes 20' with a smaller diameter. The inner wall surface of the right through hole of each of the two substrates is covered with a light-absorbing and / or light-reflecting coating 30.

[0087] FIG. 2(b) shows an illumination device for directing light onto a structured substrate 1, 1' through holes in the substrate.

[0088] 2(c) shows a top view of one of the flat surfaces of the structured substrate 1, 1', as the light-absorbing and / or light-reflecting coating 30 covering the inner wall surface of the through-hole on the right is seen from the side to form an outline surrounding the through-hole. As can be seen, the light-absorbing and / or light-reflecting coating 30 significantly improves the detectability of the through-hole, which acts as a reference point, thus optimizing the assembly of microsystems in particular.

[0089] Figure 3 shows a substrate 10 with L-shaped through-holes 20 that form non-mirror symmetric alignment markers for detecting different configurations of the substrates relative to one another. Figure 4 shows that rotation between two through-holes 20, 20' (and the corresponding substrates) can be detected (a), incorrect orientation (top of top surface vs. bottom of top surface) can be detected (b), and displacement can be detected (c).

[0090] FIG. 5 shows an example of a process for manufacturing a layered assembly comprising a structured substrate 1 and two optical substrates 60, the process comprising steps (a) to (d).

[0091] In steps (a) and (b), lower optical substrate 60 is aligned with structured substrate 1, which corresponds to structured substrate 1 in FIG. 1(d). For this purpose, optical substrate 60 is provided with alignment markers 64, for example, printed or laser ablated on the surface of the material. These alignment markers 64 are aligned with small outer through-holes 20′ of structured substrate 1. Optical elements 62 of optical substrate 60 are thereby aligned with large inner through-holes 20 of structured substrate 1, allowing the optical elements to be embedded in the through-holes when optical substrate 60 and structured substrate 1 are connected.

[0092] In steps (c) and (d), another optical substrate 60 is aligned and connected to the structured substrate 1 in a similar manner to above, resulting in a micro-optical assembly comprising three substrate layers. In a further isolation step, the micro-optical assembly can be cut along parting lines 70.

[0093] FIG. 6 is a microscope image showing a side view of a substrate 10 having a plurality of holes arranged in a fan-like configuration. Each hole has a central axis, indicated by reference numeral 100. The angle between the central axis and the surface normal of the flat surface 12 of the substrate 10 varies to form the fan-like configuration. Note that in this illustration, the angle beta is measured relative to the surface. The angle relative to the surface normal is alpha = beta - 90°. In the state shown in FIG. 6, the holes are not yet configured as through-holes 20, as shown in FIGS. 7, 8, and 9, for example, but are configured as blind holes. The through-holes 20 may be obtained by thinning the substrate 10, for example, by grinding and polishing.

[0094] 7 is a microscope image showing a perspective view of a structured substrate 1 having a plurality of through-holes 20 within the substrate 10 arranged in a regular pattern. The through-holes 20 shown have identical configurations and are arranged in a row pattern, with the through-holes 20 equally spaced within a row but with two adjacent rows offset.

[0095] 8 is a microscope image showing a perspective view of a cut structured substrate 1 having a plurality of through-holes 20 arranged in a regular pattern. The through-holes 20 shown have identical configurations and are arranged in a row pattern, with the through-holes being equally spaced within a row but with two adjacent rows being offset.

[0096] The shape of each of the through-holes 20 is hourglass-shaped in this embodiment, such that the diameter of the through-hole 20 is greatest at the flat surface and decreases to its smallest diameter.

[0097] The structured substrate 1 of Figures 7 and 8 is particularly useful in optical filters, especially spatial filters. One example of such an application is as a stray light filter in an X-ray detector.

[0098] 9 is a microscope image showing a side view of a further embodiment of a structured substrate 1 having a plurality of hourglass-shaped through-holes 20 obtained by a combined laser and etching process. The through-holes 20 are arranged in this example in a regular pattern of rows and columns with equal spacing between the rows and columns.

[0099] FIG. 9 shows a side view of a cut substrate 10 having a thickness of 580 μm, revealing the hourglass-shaped structure of the through-hole 20. The through-hole 20 has two conical sections, each with a diameter that is largest at the flat surfaces 12, 14 of the substrate 10 and decreases to a minimum diameter located between the two conical sections. In the illustrated example, the two conical sections are unequal, with one section being larger than the other. Alternatively, the hourglass shape could be configured to form two equal conical sections. In the illustrated example, the central axis 102 of the through-hole 20 is perpendicular to the flat surfaces 12, 14 of the substrate 10.

[0100] In the example of Figure 9, the first conical section abutting the first flat surface 12 of the substrate 10 has a diameter of 99.44 µm at the first flat surface 12. The diameter of the first conical section decreases until it reaches a minimum diameter. The angle of the conical wall was set to 5.5° in this example, but slight variations in the process can cause the angle to vary from about 4.75° to about 6.45°. However, by applying the same process to each of the multiple through holes, shape variation among the multiple through holes is reduced.

Claims

1. a flat substrate (10), preferably comprising a glass material and having two opposing flat surfaces (12, 14); at least one through hole (20) extending through the material of the planar substrate forming an interior wall surface surrounding the through hole and connecting the two opposing planar surfaces (12, 14); a coating (30) covering at least some area of ​​the inner wall surface of the through hole, the coating (30) being light absorbing and / or light reflective; A structured substrate (1), preferably for applications in microsystems technology, such as micro-optical systems, comprising: one or both of said flat surfaces (12, 14) does not include said coating (30); the inner wall surface has an arithmetic mean roughness between 0.1 μm and 2 μm, preferably between 0.2 μm and 1 μm, more preferably between 0.4 μm and 1 μm; and / or the coating (30) has an arithmetic mean roughness between 0.05 μm and 2 μm, preferably between 0.1 μm and 1 μm, more preferably between 0.2 μm and 0.5 μm; A structured substrate (1) characterized in that:

2. the angle of the inner wall surface relative to the flat surface (12, 14) and / or the angle of the central axis of the through hole (20) relative to the flat surface (12, 14) is 90° + / - 1°, preferably + / - 0.5°, more preferably + / - 0.25°; and / or the at least one through-hole (20) is conical in shape, such that the diameter of the at least one through-hole (20) decreases or increases from one planar surface (12) of the flat substrate to the other planar surface (14); and / or the at least one through hole (20) has an hourglass shape such that the diameter of the at least one through hole (20) decreases from each of the flat surfaces (12, 14) toward a central portion having a smallest diameter; A structured substrate (1) according to claim 1.

3. the angle of the inner wall surface relative to the normal defined by the flat surfaces (12, 14) is in the range of greater than 0° to 15°, preferably in the range of 5° to 10°; and / or the angle of the central axis of the through hole (20) relative to the normal defined by the flat surfaces (12, 14) is in the range of greater than 0° to 15°, preferably in the range of 5° to 10°; A structured substrate (1) according to claim 1.

4. The flat substrate (1) has a thickness (t) extending from one flat surface (12) to the other flat surface (14), the thickness (t) being between 20 μm and 8 mm, preferably between 50 μm and 4 mm, more preferably between 100 μm and 3 mm, and most preferably between 250 μm and 1 mm; A structured substrate (1) according to any one of claims 1 to 3.

5. the through holes (20) have a diameter (d) between 0.3 μm and 10 mm; and / or The through holes (20) have a diameter (d) between 0.3 μm and 300 μm, Preferably, the diameter of the through hole (20) is the smallest dimension of the through hole (20) parallel to the plane defined by the flat surfaces (12, 14) of the flat substrate (1). A structured substrate (1) according to any one of claims 1 to 4.

6. the through holes (20) define an aspect ratio, which is the ratio between the diameter (d) of the through holes and the thickness (t) of the flat substrate, said aspect ratio being between 0,000075 and 17.5, preferably between 0,0001 and 10, more preferably between 0,00015 and 5, more preferably between 0,0003 and 2, more preferably between 0,001 and 1; Preferably, the diameter (d) of the through hole (20) is the smallest dimension of the through hole (20) parallel to the plane of the flat substrate (1), 6. The structured substrate of claim 1.

7. the coating (30) has a thickness between 5 nm and 5000 nm, preferably between 15 nm and 1000 nm, more preferably between 50 nm and 500 nm; A structured substrate (1) according to any one of claims 1 to 6.

8. the coating (30) covers the entire area of ​​the inner wall surface, or said coating (30) covers at least 10%, preferably at least 50%, more preferably at least 90%, and most preferably the entire area of ​​said inner wall surface; and / or the inner wall surface is partially, in particular at least 10% along the thickness direction of the substrate, free from the coating (30); A structured substrate (1) according to any one of claims 1 to 7.

9. one or both of said flat surfaces (12, 14) are polished, and / or one or both of said flat surfaces (12, 14) has an RMS roughness of less than 10 nm, preferably less than 5 nm, more preferably less than 1 nm, more preferably less than 0.5 nm, more preferably less than 0.1 nm; and / or The flatness (TTV: total thickness variation) of the flat substrate (10) is less than 5 μm; A structured substrate (1) according to any one of claims 1 to 8.

10. said coating (30) having an extinction coefficient of at least 0.01, preferably at least 0.05, more preferably at least 0.1 for at least one wavelength in the range of 250 nm to 1600 nm, preferably in the range of 400 nm to 750 nm, more preferably for all wavelengths within one of said ranges; and / or the coating (30) has an extinction coefficient for at least one wavelength in the range of 250 nm to 1600 nm, preferably in the range of 400 nm to 750 nm, more preferably for all wavelengths within one of said ranges, such that an attenuation of 20 dB is achieved across the thickness of the flat substrate; and / or the coating (30) has a reflectivity of more than 60%, preferably more than 80%, more preferably more than 90%, particularly preferably more than 95%, even more preferably more than 99%, and most preferably more than 99.9%; A structured substrate (1) according to any one of claims 1 to 9.

11. The coating (30) is made of the following materials: Al ２ O ３ , B ２ O ３ , Co ２ O ３ , Cr ２ O ３ ,CuO,Fe ２ O ３ , Ga ２ O ３ , HfO ２ , In ２ O ３ , MgO, Nb ２ O ５ , NiO, Pd, Pt, Al, Ag, Mo, W, SiO ２ , SnO ２ , Ta ２ O ５ , TiO ２ , TaNx, (Ta, Al)N, TiCrOx, (Ti, Al)N, (Ti, Al)C TiC, AlC, AlN, TiN, VO ２ , W.O. ３ , ZnO, (Al, Zn)O, ZnS, ZnSe, ZrO ２ , rare earth (RE) oxides, Sc ２ O ３ , Y ２ O ３ , carbon, carbon black, Ca １０ (P.O. ４ ) ６ (OH) ２ ), polyimide, PMDA-ODA, PMDA-DAH, 3-aminopropyltrimethoxysilane coupling agent, A structured substrate (1) according to any one of claims 1 to 10.

12. the flat substrate (10) comprises a glass material, a ceramic material, a glass-ceramic material and / or a crystalline material, for example sapphire; and / or The flat substrate (10) comprises the following components: At least 30 wt%, preferably at least 50 wt%, more preferably at least 80 wt% SiO ２ At least one of the following contents is included: A structured substrate (1) according to any one of claims 1 to 11.

13. the structured substrate (1) comprises a plurality of through holes (20) extending through the material of the flat substrate (10), each forming an inner wall surface surrounding a respective through hole (20) and connecting the two opposing flat surfaces (12, 14) of the flat substrate (10); and / or the through hole (20), or when a plurality of through holes (20) are present, is non-mirror symmetrical and / or non-circular, preferably with at least one of the plurality of through holes (20) having an L-shaped cross section, e.g., including one or more rectangular portions; A structured substrate (1) according to any one of claims 1 to 12.

14. providing a flat substrate (10), preferably comprising a glass material and having two opposing flat surfaces (12, 14); at least one through hole (20) extending through the material of the planar substrate (10) to form an interior wall surface surrounding the through hole (20) and connecting the two opposing planar surfaces (12, 14); depositing a light-absorbing and / or light-reflecting coating (30) on the flat substrate (10) covering at least some areas of the inner wall surface of the through-hole (20); treating, preferably polishing, one or both of the flat surfaces (12, 14) of the flat substrate (10) to remove any coating covering said flat surfaces (12, 14) so ​​that said one or both of said flat surfaces (12, 14) is free of said coating (30); A method for manufacturing a structured substrate (1) according to any one of claims 1 to 13, comprising:

15. the coating (30) is deposited on the flat substrate (10) by vacuum deposition, preferably by physical vapor deposition (PVD) or chemical vapor deposition (CVD), preferably by atomic layer deposition (ALD) or plasma-enhanced chemical vapor deposition (PECVD); A method for manufacturing a structured substrate (1) according to claim 14.

16. To align the structured substrate (1) with another element, Preferably, the structured substrate (1) is observed from above on one of the flat surfaces (12, 14) of the structured substrate, and the coating (30) covering the inner wall surface is seen from the side to form a contour surrounding the through hole (20); Preferably, the position of the contour surrounding the through-hole (20) is compared with a defined position on the other element. Use of a structured substrate (1) according to any one of claims 1 to 13.

17. the position error between the contour surrounding the through-hole (20) and the defined position on the other element, preferably in the x-y plane, is reduced to less than 2 μm, preferably 1 μm, more preferably less than 0.1 μm, even more preferably less than 50 nm; and / or the position error between the contour surrounding the through-hole (20) and the defined position on the other element, preferably in the z-direction, more preferably over the entire area of ​​the substrate, is reduced to less than 20 μm; and / or the structured substrate (1) and / or the further element are provided with markings introduced by ion beam treatment, the markings preferably being used to align and / or assist in aligning the structured substrate (1) with respect to the further element, Use of a structured substrate (1) according to claim 16.

18. A microsystem, preferably a micro-optical system, comprising: Preferably, the micro-optical system comprises a plurality of layers, at least one of which is formed as the structured substrate (1), Preferably, stray light within the microsystem is reduced by a coating (30) covering the inner wall surfaces of the through holes (20) extending through the material of the flat substrate (10) of the structured substrate (1). Use of a structured substrate (1) according to any one of claims 1 to 13 for manufacturing a micro-optical system.

19. Assembly comprising a layer structure of two or more layers, at least one of said layers being a structured substrate (1) according to any one of claims 1 to 13.

20. 20. The assembly of claim 19, comprising at least one further substrate layer having at least one marking corresponding to the at least one through hole (20) of the structured substrate (1), wherein the at least one marking of the further substrate layer and the at least one through hole (20) of the structured substrate (1) are aligned.

21. 14. An assembly comprising at least three layers, in this order: a first micro-optical layer, a structured substrate (1) according to any one of claims 1 to 13, and a second micro-optical layer.

22. 14. A beam trap comprising a structured substrate (1) according to any one of claims 1 to 13 and a further substrate connected to the structured substrate (1), wherein the further substrate comprises at least one blackened and / or roughened surface.

23. A stray light filter element comprising a structured substrate (1) according to any one of claims 1 to 13, characterized in that the structured substrate (1) comprises an array of through holes (20).

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