Structured substrate, method for producing said structured substrate and use of said structured

Abstract

The invention relates to a structured substrate (1), preferably for use in microsystem technology, for example for micro-optical systems, comprising: a flat substrate (10), preferably comprising a glass material and having two opposite flat surfaces (12, 14); at least one through-hole (20) penetrating the material of the planar substrate (10), thereby forming an inner wall surface surrounding the through-hole (20) and connecting the two opposing planar surfaces (12, 14); and a light-absorbing and / or reflective coating (30) covering at least a partial region of the inner wall surface of the through hole (20) wherein one or both of the two opposing flat surfaces (12, 14) are free of the coating (30). The arithmetic mean roughness of the inner wall surface is between 0.2 [mu] m and 2 [mu] m, and / or the arithmetic mean roughness of the coating (30) is between 0.05 [mu] m and 2 [mu] m. The invention also relates to a method for producing said structured substrate and to the use of said structured substrate.

Description

Technical Field

[0001] The invention relates to a structured substrate, preferably a structured substrate for microsystems technology, for example for micro-optical systems. Background Art

[0002] In microsystem technology, multiple wafers or substrates are usually stacked on top of each other to form a layered system, for example, to manufacture micro-optical elements. At the wafer level, hundreds of optical devices are usually manufactured on each wafer. For more complex optical systems, such as the imaging optical system of a smartphone, it is necessary to combine multiple such functional wafers in a layered system. In the cutting step, individual devices are thus obtained. Typically, such a layered system also includes a spacer wafer or a spacer substrate to provide the required distance between the functional layers containing the optical elements. Such a spacer wafer is a flat glass wafer with a predetermined thickness and provides a plurality of through holes, which have at least the same diameter as the individual optical elements of the functional wafer. However, depending on the surface of the through hole, the final device may experience unwanted reflections, reduced contrast, artifacts or other interferences.

[0003] When manufacturing such microsystems, alignment of multiple wafers or substrates relative to each other is crucial to ensure the functionality of the micro-optical device. For such alignment of wafers or substrates, printed or ablated surface marks are usually used. However, such near-surface marks may have the disadvantage of parallax errors. Another option is to use through-holes on the wafer or substrate as alignment marks or reference points. However, due to the low contrast of the through-hole marks, pattern recognition of such through-holes is challenging. Misalignment of lenses relative to each other can affect imaging performance. The more compact the micro-optical system (e.g., with high-refractive-index lenses), the smaller the tolerance. Summary of the invention

[0004] It is therefore an object of the present invention to reduce stray light, reflections, artifacts or other disturbances on the spacer substrate in layered micro-optical elements to improve contrast and, in particular, to optimize the assembly of microsystems by improving pattern recognition of through-holes.

[0005] To achieve this object, a structured substrate is disclosed, preferably a structured substrate for microsystem technology, such as micro-optical systems, according to claim 1 .

[0006] The structured substrate includes a flat substrate having two opposite flat surfaces. The flat substrate may include a brittle material, such as glass, ceramic, glass ceramic, etc., as described below.

[0007] The structured substrate further includes at least one through hole penetrating through the material of the planar substrate, thereby forming an inner wall surface surrounding the through hole and connecting the two opposing planar surfaces.

[0008] Further, the structured substrate comprises a coating covering at least a portion of the inner wall surface of the through hole, wherein the coating has the function of absorbing light and / or reflecting light.

[0009] For alignment purposes, vertical or nearly vertical walls are preferred.Therefore, in some embodiments of the present invention, the angle between the inner wall surface and the flat surface may be 90°±1°, preferably 90°±0.5°, more preferably 90°±0.25°.

[0010] However, for other uses, such as, for example, a beam trap, a conical design may also be used. Therefore, in some embodiments of the present invention, the at least one through hole is conical, with its diameter decreasing or increasing from one flat surface to another flat surface of the substrate. The angle of the cone is preferably 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 between the inner wall and the normal to the plane defined by the flat surface of the substrate.

[0011] Further, the at least one through hole may be hourglass-shaped, with its diameter decreasing from each of the flat surfaces to the central portion with the smallest diameter. Each of the two conical sections of the hourglass shape may have an angle ranging from 0.5° to 15°, preferably 1° to 12°, even preferably 2° to 10°, and most preferably 4° to 8°. The two conical sections of the hourglass shape may have the same angle. Alternatively, the two conical sections may have different angles.

[0012] Preferably, the angle between the central axis of the at least one through hole and the flat surface of the substrate is set to be perpendicular to the flat surface, so the angle between the central axis of the through hole and the flat surface can be 90°±1°, preferably 90°±0.5°, and even preferably 90°±0.25°. Alternatively, the through hole can be configured to be at an angle with the normal defined by the flat surface of the substrate, so the angle between the central axis of the through hole and the normal defined by the flat surface can range from 0° to 15°, preferably 1° to 12°, and more preferably 5° to 10°. For example, a through hole array for suppressing stray light incident on an X-ray detector can be composed of a hole array, wherein each row or each row group of through holes has a different inclination relative to the normal of the surface, for example, the arrangement can be 5 rows of 0° holes, 5 rows of 1° holes, and other rows of groups, until the last group of 5 rows of 10° holes. Therefore, such a filter can provide a fan-shaped through hole combination.

[0013] Typically, the thickness of the planar substrate (ie the dimension extending from one planar surface to the other) is between 20 μm and 8 mm, preferably between 50 μm and 4 mm, more preferably between 100 μm and 3 mm, most preferably between 250 μm and 1 mm.

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

[0015] In some embodiments of the invention, the diameter of the through hole may be between 0.3 μm and 10 mm. Such diameters, diameters in the range of 5 μm and 10 mm, or larger diameters in the millimeter range, may be more suitable for optical cavities, for example, for reducing stray light in micro-optical elements.

[0016] In some embodiments of the invention, the diameter of the through-holes may be between 0.3 μm and 300 μm. Such diameters may be more suitable for alignment purposes, and are preferably selected so that the structure used for alignment completely fills 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 of the diameter of the via to the thickness of the planar substrate.

[0018] For example, such an aspect ratio may be 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] It is possible to consider coating the inner wall surface of the through hole before coating. If the roughness is within the wavelength range of the light used (eg, ultraviolet range, visible range, and near infrared range), the effect is more ideal.

[0020] In some embodiments of the present invention, the arithmetic mean roughness of the inner wall surface is 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 may also be considered, i.e., the roughness of the coating itself. It should be noted that the roughness before and after coating may depend on the coating technique and parameters. For example, in the case of using atomic layer deposition (ALD) technology, the roughness of the surface may be retained, especially in the case of a very thin ALD layer deposited. If the deposited layer is thicker (e.g., thicker than 250nm) or other coating techniques are used, the original roughness of the inner wall may be reduced.

[0022] In some embodiments of the present invention, the arithmetic mean roughness of the coating may be 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 thickness of the coating may be between 5 nm and 5 μm, preferably between 15 nm and 1000 nm, more preferably between 50 nm and 500 nm.

[0024] Typically, the inner wall of the through hole may be fully 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 inner wall surface.

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

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

[0028] One or two of the flat surfaces may be polished. In some embodiments, the RMS roughness of one or both of the flat surfaces may be 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. By polishing one or both of the surfaces, this surface roughness can be advantageously achieved without additional effort. This low roughness may be particularly advantageous when a layered system is formed by stacking substrates on top of each other. Therefore, the step of connecting layers in production can be optimized. Smaller RMS roughness can improve contact bonding, sprueing and / or optical manufacturing tolerances.

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

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

[0031] In some embodiments of the present invention, the coating may have an absorption coefficient α and / or an extinction coefficient κ of at least 0.01, preferably at least 0.05, more preferably at least 0.1 for at least one wavelength λ0 in the range of 250nm to 1600nm, preferably in the range of 400nm to 750nm, and more preferably for all wavelengths in any of the ranges.

[0032] The complex refractive index can be written as n =n-iκ. The extinction coefficient is the imaginary part, whose value is κ. The absorption coefficient can be written as α=4πκ / λ0, where λ0 is the vacuum wavelength. Correspondingly, the penetration depth (i.e., the distance after the intensity decreases by 1 / e) is δp=1 / α=λ0 / 4πκ.

[0033] In some embodiments of the present invention, the coating may have an absorption coefficient and / or an extinction coefficient for at least one wavelength in the range of 250nm to 1600nm, preferably in the range of 400nm to 750nm, and preferably for all wavelengths in any of the ranges, thereby achieving a damping of 20dB over the thickness of the flat substrate.

[0034] For example, in VIS spectroscopy, the absorption coefficient or extinction coefficient defined above may be more suitable for alignment purposes.

[0035] In some embodiments of the present invention, it is foreseeable that the coating is configured to reflect light, particularly for a given design wavelength or wavelength range. In such a configuration, the reflectivity of the coating may be greater than 60%, preferably greater than 80%, more preferably greater than 90%, particularly more preferably greater than 95%, even more preferably greater than 99%, and most preferably greater than 99.9%. For example, the absorbance and / or reflectivity of the coating may be reflected in the ultraviolet-near infrared (UV-NIR) spectrum.

[0036] If the coating is configured to be primarily light reflective, it is preferred that the coating has no light absorption or only a small amount of light absorption, especially 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] Likewise, if the coating is configured to be primarily light absorbing, it is preferred that the coating has no light reflectivity or only a small amount of light reflectivity, particularly for a given design wavelength or wavelength range. Preferably, the light reflectivity 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] For example, the design wavelength range is between 250 nm and 1600 nm, or is a visible light range between 400 nm and 750 nm.

[0039] The coating generally comprises or consists of a metal, a metal nitride, a metal carbide or a metal oxide. In some cases, metallic materials are preferred, followed by metal nitrides and carbides. It should be noted that materials compatible with the process described below can be selected.

[0040] In some embodiments of the present invention, the coating may include at least one 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) oxide, Sc2O3, Y2O3, carbon, carbon black, Ca 10 (PO4)6(OH)2), polyimide, PMDA-ODA, PMDA-DAH, 3-aminopropyltrimethoxysilane coupling agent.

[0041] The coating may be configured as a multilayer structure comprising a plurality of layers. A specific example is a coating configured to be reflective, which may be constructed as a dielectric mirror comprising a plurality of alternating layers having different refractive indices.

[0042] As mentioned above, the coating can be applied by one or more of several processes. For example, the light absorbing coating can 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 described above, the flat substrate may include or consist of glass, fused quartz, ceramic, glass ceramic and / or crystal (eg, sapphire). In certain embodiments, polymer or plastic materials may also be used.

[0044] In a preferred embodiment, the planar substrate comprises a glass material, a ceramic material, a glass-ceramic material and / or a crystalline material (eg, sapphire).

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

[0046] In yet another embodiment of the present invention, the structured substrate may include a plurality of through holes penetrating the material of the planar substrate, wherein each through hole forms an inner wall surface surrounding the through hole and connecting two opposite planar surfaces of the planar substrate.

[0047] In such a plurality of through holes, each through hole may have exactly the same configuration. Alternatively, all through holes or groups of more than one through hole may have different configurations, wherein, for example, the angle of the inner wall, the angle of the central axis, the diameter of the through hole, or one or more of the above parameters may be different. For example, the angle of the central axis of one through hole may be different from the angle of the central axis of an adjacent through hole to form a fan-like arrangement of the through holes.

[0048] For certain uses of the structured substrate, for example, as a spatial light filter element, the structured substrate may include an array of through holes. In this configuration, through holes of the same structure are preferably arranged in a regular two-dimensional grid pattern. This pattern can be configured as a square or rectangular arrangement with a row and column structure, wherein the distances between each row and each column are equal. Other configurations include triangular or hexagonal patterns.

[0049] For example, the distance between two rows and / or two columns is selected from the range of 2 μm to 1 mm, preferably from the range of 20 μm to 400 μm, more preferably from the range of 100 μm to 300 μm. Preferably, the distance or pitch P between two adjacent through holes is selected relative 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 as P>1.1W, more preferably P>1.5W, most preferably P>2W.

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

[0051] The at least one through hole or at least one of the plurality of through holes may have a non-mirror-symmetrical and / or non-circular cross-section, preferably comprising one or more rectangular sections, for example in an L-shape.

[0052] Such a shape may be more suitable for substrate alignment. Typically, the at least one or more through holes may be designed so that: (i) offset is detectable; (ii) rotation is detectable; and / or (iii) incorrect orientation (top side to top side vs. bottom side to top side) is also detectable. In particular, the number, size and / or shape of the at least one or more through holes are designed to ensure these conditions. An L-shaped through hole is an example. However, there are many other suitable designs.

[0053] The invention also relates to a method of manufacturing a structured substrate, preferably as described above.

[0054] The method comprises providing a planar substrate, preferably a planar substrate comprising a glass material and having two opposite planar surfaces, wherein at least one through hole is inserted into or penetrates the material of the planar substrate to form an inner wall surface surrounding the through hole and connecting the two opposite planar surfaces.

[0055] The method further includes depositing a light absorbing coating and / or a light reflecting coating on the flat substrate to cover at least a portion of the inner wall surface of the through hole.

[0056] The method may further comprise treating (preferably polishing) one or both of the flat surfaces of the flat substrate to remove the coating covering the flat surface, leaving the flat surface free of the coating. It may be polished to achieve an RMS roughness of less than 10 nm, preferably less than 5 nm, and more preferably less than 1 nm. For polishing, see John Wiley & Sons, October 16, 2018, Materials Science and Technology of Optical Fabrication, pp. 319-352, Chapter 8, "novel polishing methods".

[0057] The method may comprise inserting the at least one through hole into the material of the flat substrate. In particular, at least one filament or filamentary damage may be introduced into the material of the substrate by means of a laser process. Such a filament may have a diameter of about 0.1 μm-0.5 μm, for example 0.3 μm. Preferably, in a next step, the filament may be extended by etching. Furthermore, a plurality of filaments may be introduced. By placing a plurality of filaments closely together, through holes of almost any shape and size may be produced. It should be noted that etching may also be omitted if only small through holes are desired.

[0058] If the structured substrate comprises more than one through hole, the relative position accuracy of two adjacent through holes relative to the center of the through hole is preferably greater than 2%, more preferably greater than 1%, and most preferably greater than 0.1%. Preferably, the absolute positioning accuracy is within the range of ±0.5 μm. If a regular pattern is used (such as a row and column pattern), the average deviation from the set spacing is preferably less than 0.2 μm, more preferably less than 0.02 μm.

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

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

[0061] The present invention also relates to the use of a structured substrate, preferably as described above, for aligning the structured substrate relative to another element, wherein preferably, one of the flat surfaces of the structured substrate is observed in a top view, so that the coating covering the inner wall surface is visible, which forms a contour around the through hole in a side view, wherein, preferably, the position of the contour around the through hole is compared with a defined position on the other element.

[0062] Such a defined position can be, for example, a mark on another wafer which comprises a functional element such as a micro-optical element, a light sensor or a transmitter.

[0063] It should be noted that the top view of one of the planar surfaces need not be performed directly on said surface, but may also be performed through other substrates or layers, especially in microsystems comprising multiple layers.

[0064] In a specific embodiment, the further element may be a second structured substrate, preferably as described above. The structured substrate and the second structured substrate are positioned one on top of the other, with one planar surface of the structured substrate facing one planar surface of the second structured substrate. The structured substrate and the second structured substrate are both observed from a top view, thereby simultaneously forming an outline around the through hole of the structured substrate and a second outline around the through hole of the second structured substrate, and comparing the position of the outline with the position of the second outline.

[0065] When using the structured substrate, the position error (preferably position error on the xy plane) between the contour around the through hole and the defined position on the other element can be reduced to below 2 μm, preferably below 0.1 μm, more preferably below 50 nm.

[0066] Furthermore, a position error between the contour around the through hole and the defined position on the further element, preferably a position error in the z-direction, more preferably a position error over the entire area of ​​the substrate, may be reduced to below 20 μm.

[0067] It is also conceivable that the structured substrate and / or the further element comprises marks introduced by ion beam processing, wherein preferably the marks serve to align and / or assist in aligning the structured substrate relative to the further element.

[0068] The invention also relates to the use of the structured substrate described above for producing a microsystem, preferably a micro-optical system.

[0069] Preferably, the micro-optical system comprises a plurality of layers, wherein at least one of the layers is configured as the structured substrate.

[0070] For example, three layers may be stacked, wherein the middle layer may be the structured substrate described above. In particular, such a middle layer may be a spacer layer. The other layers or outer layers may be configured with micro-optical refractive or diffractive elements. In this example, as described above, preferably, the two micro-optical outer layers and the spacer inner layer are aligned with each other.

[0071] Preferably, stray light in the microsystem is reduced by covering the inner wall surface of the through hole, in particular a light absorbing but non-reflective coating, wherein the through hole penetrates the material of the planar substrate of the structured substrate.

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

[0073] The assembly may comprise at least one further substrate layer having markings corresponding to the through-holes of the structured substrate, wherein the markings of the further substrate layer are aligned with the through-holes of the structured layer (preferably as described above).

[0074] The assembly may include at least three layers, in order, a first micro-optical layer, the structured substrate described above, and a second micro-optical layer.

[0075] Such three layers can be regarded as forming a unit cell, and more than three layers, for example, five layers, can also be stacked into two such units, wherein the middle layer belongs to the two units.

[0076] The present invention further relates to a beam dump, comprising the structured substrate described above and a further substrate connected thereto, wherein the further substrate comprises at least one blackened and / or roughened surface.

[0077] Generally, the present invention is applicable at least to wafer bonding, stacked transparent elements, micro-optical elements, wafer-level alignment, stray light suppression, glass circuit boards, microsensors (such as wafer-level sensors or pressure sensors), microfluidics, lidar sensors, sensor arrays, and wafer-level packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The present invention will be described in more detail below with reference to the accompanying drawings.

[0079] Figure 1 Side views of process steps (a)-(d) for making a structured substrate are shown.

[0080] Figure 2Shown are a side view of two stacked structured substrates (a), another side view of the two stacked structured substrates being illuminated (b), and a top view of the two stacked structured substrates (c).

[0081] Figure 3 A top view of a substrate having an L-shaped through hole is shown.

[0082] Figure 4 The alignment of two L-shaped through holes relative to each other is schematically shown.

[0083] Figure 5 Side views of process steps (a)-(d) for fabricating a layered assembly including a structured substrate and an optical substrate are shown.

[0084] Figure 6 A side view of a structured substrate having holes arranged in a fan-shaped manner is shown.

[0085] Figure 7 A perspective view of a structured substrate having a plurality of holes arranged in a regular pattern is shown.

[0086] Figure 8 A perspective view of a cut structured substrate having a plurality of holes arranged in a regular pattern is shown.

[0087] Fig. 9 A side view of a structured substrate having a plurality of hourglass-shaped through-holes is shown. DETAILED DESCRIPTION

[0088] Figure 1 An example of a process for manufacturing a structured substrate 1 is shown, wherein the process comprises steps (a) to (d).

[0089] In step (a), a flat substrate 10 is provided, wherein the flat substrate comprises two opposite flat surfaces 12, 14 and a plurality of through holes 20, 20' penetrating a thickness t of the flat substrate.

[0090] Some through holes 20 have a larger diameter d than other through holes 20'. The through holes 20 with a larger diameter d can be designed to accommodate an optical element 62 (see Figure 5 ), while the through hole 20' having a smaller diameter d can be used to align multiple substrates stacked on top of each other.

[0091] In step (b), a light absorbing and / or light reflecting coating 30 is deposited on a flat substrate to cover at least a portion of the inner wall surface of the through-holes 20, 20'. The thickness of such a coating may be, for example, between 5 nm and 5 μm, and may be configured to absorb and / or reflect light within a specific wavelength range (e.g., UV-NIR). The coating may be applied, for example, by atomic layer deposition (ALD), or by other coating techniques, such as ion beam coating or liquid coating. In this particular example, the light absorbing and / or light reflecting coating 30 covers not only the inner wall surface of the through-holes 20, 20', but also the two opposing flat surfaces 12, 14 of the substrate 10.

[0092] Therefore, in step (c), the flat surfaces 12, 14 of the substrate 10 are polished to remove the coating covering the flat surfaces 12, 14, so that the flat surfaces 12, 14 are free of light absorbing coating and / or light reflecting coating. The polishing can be performed using a polishing medium 40. It is also conceivable that the flat surfaces 12, 14 are plasma etched or laser ablated to remove the coating covering the flat surfaces 12, 14. In particular, if the polishing is used to improve the surface quality of the flat surface, the polishing can also consist of multiple polishing steps. With the reduction of the grain size, an RMS roughness of less than 1 nm or even less than 0.1 nm can be obtained. In addition, the polishing can also be used to compensate for the total thickness variation (TTV) of the wafer.

[0093] The structured substrate 1 obtained as shown in (d) comprises a flat substrate 10 having a plurality of through holes 20, 20', which penetrate the material of the flat substrate 10 and form inner wall surfaces surrounding the through holes 20, 20' and connecting two opposite flat surfaces 12, 14, wherein a light absorbing and / or light reflecting coating 30 covers the inner wall surfaces of the through holes 20, 20'.

[0094] Figure 2 (a) shows two stacked structured substrates 1, 1', wherein the upper substrate 1 includes two adjacent through holes 20 with a larger diameter, and the lower substrate 1' includes two adjacent through holes 20' with a smaller diameter. The inner wall surfaces of the right through holes on both substrates are covered with a light absorbing and / or light reflecting coating 30.

[0095] Figure 2 (b) shows an illumination device for guiding light onto the structured substrate 1, 1' and through the through holes in the substrate.

[0096] Figure 2(c) shows a flat surface of the structured substrate 1, 1' observed in a top view, making visible the light-absorbing and / or light-reflecting coating 30 covering the inner wall surface of the through hole on the right, which forms a contour around the through hole in a side view. It can be seen that the light-absorbing and / or light-reflecting coating 30 significantly improves the detectability of the through hole as a reference point, thereby particularly optimizing the assembly of the microsystem.

[0097] Figure 3 A substrate 10 is shown with an L-shaped through hole 20 that forms a non-mirror-symmetrical alignment mark to detect different configurations of the substrates relative to each other. Figure 4 As shown, rotation (a) between two vias 20, 20' (and corresponding substrates) is detectable, incorrect orientation (top side to top side versus bottom side to top side) (b) is detectable, and offset (c) is detectable.

[0098] Figure 5 An example of a process for manufacturing a layered assembly comprising a structured substrate 1 and two optical substrates 60 is shown, wherein the process comprises steps (a)-(d).

[0099] In steps (a) and (b), the lower optical substrate 60 is aligned with the structured substrate 1, which corresponds to Figure 1 (d) The optical substrate 60 includes an alignment mark 64, for example, a mark printed or laser ablated in the surface of the material. These alignment marks 64 are aligned with the smaller outer through holes 20' of the structured substrate 1. As a result, the optical elements 62 of the optical substrate 60 are aligned with the larger inner through holes 20 of the structured substrate 1, so that when the optical substrate 60 is connected to the structured substrate 1, the optical elements 62 of the optical substrate 60 are embedded in the larger inner through holes 20 of the structured substrate 1.

[0100] In steps (c) and (d), another optical substrate 60 is aligned and connected to the structured substrate 1 in a similar manner to generate a micro-optical component including three substrate layers. In a further segmentation step, the micro-optical component can be segmented along segmentation lines 70 .

[0101] Figure 6 is a microscope image showing a side view of a substrate 10 having a plurality of holes arranged in a fan-shaped manner. Each hole has a central axis, which has been marked with 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-shaped arrangement. Note that in this figure, the angle β is measured relative to the surface. The angle relative to the surface normal is α = β - 90°. In Figure 6 In the state shown, the holes have not yet been configured as Figure 7 , Figure 8 and Fig. 9 The through hole 20 is not shown as a blind hole. The through hole 20 may be obtained by thinning the substrate 10 (eg by grinding and polishing).

[0102] Figure 7 is a microscope image showing a perspective view of a structured substrate 1 having a plurality of regularly arranged through holes 20. The through holes 20 shown have the same structure and are arranged in a row pattern, wherein the pitch of the through holes 20 in a row is equal, but two adjacent rows are offset from each other.

[0103] Figure 8 is a microscope image showing a perspective view of a cut structured substrate 1 having a plurality of regularly arranged through holes 20. The through holes 20 shown have the same structure and are arranged in a row pattern, wherein the pitch of the through holes in a row is equal, but two adjacent rows are offset from each other.

[0104] In this embodiment, each through hole 20 is shaped like an hourglass, so the diameter of the through hole 20 is the largest on the flat surface and gradually decreases to the smallest diameter.

[0105] Figure 7 and Figure 8 The structured substrate 1 is particularly suitable for optical filters, especially spatial filters. An example of such an application is a stray light filter in an x-ray detector.

[0106] Fig. 9 is a microscope image showing a side view of another embodiment of a structured substrate 1 having a plurality of hourglass shaped through-holes 20 obtained by a combined laser and etching process. In this example, the through-holes 20 are arranged in a regular pattern of rows and columns with equal spacing between the rows and columns.

[0107] Fig. 9 A side view of a cut substrate 10 with a thickness of 580 μm is shown, making visible the structure of the hourglass-shaped through-hole 20. The through-hole 20 has two conical parts, wherein the hole diameter of each part is greatest at the flat surfaces 12, 14 of the substrate 10 and tapers to a minimum diameter located between the two conical parts. In the example described, the two conical parts are not configured identically, so that one part is larger than the other. Alternatively, the hourglass shape can also be configured so that it is formed by two equal conical parts. In the example described, the central axis 102 of the through-hole 20 is perpendicular to the flat surfaces 12, 14 of the substrate 10.

[0108] exist Fig. 9In the example of FIG. 1 , the diameter of the first tapered portion adjacent to the first flat surface 12 of the substrate 10 at the first flat surface 12 is 99.44 μm. The diameter of the first tapered portion gradually decreases until it reaches a minimum diameter. In this example, the angle of the tapered wall is set to 5.5°, but due to slight variations in the process, the angle varies from about 4.75° to about 6.45°. However, since the process is applied to each of the plurality of through holes, the shape variations within the plurality of through holes are small.

Claims

1. A structured substrate (1), preferably used in microsystem technology, for example, in 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 planar substrate to form an inner wall surface surrounding the through hole and connecting two opposing planar surfaces (12, 14), and a coating (30) covering at least a portion of the inner wall surface of the through hole, wherein the coating (30) has a light absorbing and / or light reflecting effect, characterised in that one or both of the flat surfaces (12, 14) are free of the coating (30), The arithmetic mean roughness of the inner wall surface is 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 arithmetic mean roughness of the coating (30) is 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.

2. The structured substrate (1) according to the preceding claim, in, The angle between the inner wall surface and the flat surface (12, 14) and / or the angle between the central axis of the through hole (20) and the flat surface (12, 14) is 90°+ / -1°, preferably 90°+ / -0.5°, more preferably 90°+ / -0.25°, and / or The at least one through hole (20) is conical in shape, with its diameter decreasing or increasing from one flat surface (12) to another flat surface (14) of the flat substrate, and / or The at least one through hole (20) is hourglass-shaped, with its diameter decreasing from each of the flat surfaces (12, 14) to a central portion having a minimum diameter.

3. The structured substrate (1) according to claim 1, wherein: The angle between the inner wall surface and the normal defined by the flat surface (12, 14) ranges from greater than 0° to 15°, preferably from 5° to 10°, and / or The angle between the central axis of the through hole (20) and 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°.

4. The structured substrate (1) according to any one of the preceding claims, wherein: The flat substrate (10) has a thickness (t) extending from one flat surface (12) to the other flat surface (14), the thickness being between 20 μm and 8 mm, preferably between 50 μm and 4 mm, more preferably between 100 μm and 3 mm, most preferably between 250 μm and 1 mm.

5. The structured substrate (1) according to any one of the preceding claims, in, The diameter (d) of the through hole (20) is between 0.3 μm and 10 mm, and / or The diameter (d) of the through hole (20) is between 0.3 μm and 300 μm. The diameter of the through hole (20) is preferably the smallest dimension of the through hole (20) parallel to a plane defined by the planar surfaces (12, 14) of the planar substrate (10).

6. The structured substrate according to any one of the preceding claims, in, The through hole (20) defines an aspect ratio, i.e., a ratio of the diameter (d) of the through hole to the thickness (t) of the flat substrate, 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, The diameter (d) of the through hole (20) is preferably the smallest dimension of the through hole (20) parallel to the plane of the flat substrate (10).

7. The structured substrate (1) according to any one of the preceding claims, wherein: The thickness of the coating (30) is between 5 nm and 5000 nm, preferably between 15 nm and 1000 nm, more preferably between 50 nm and 500 nm.

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

9. The structured substrate (1) according to any one of the preceding claims, in, One or both of the flat surfaces (12, 14) are polished, and / or wherein the RMS roughness of one or both of the flat surfaces (12, 14) is 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 Wherein, the total thickness variation (TTV) of the flat substrate (10) is less than 5 μm.

10. The structured substrate (1) according to any one of the preceding claims, in, The coating (30) has 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 in any of said ranges, and / or wherein 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 in any of said ranges, the coating (30) has an extinction coefficient such that a damping of 20 dB is achieved over the thickness of the flat substrate, and / or The reflectivity of the coating (30) is greater than 60%, preferably greater than 80%, more preferably greater than 90%, particularly preferably greater than 95%, even more preferably greater than 99%, and most preferably greater than 99.9%.

11. The structured substrate (1) according to any one of the preceding claims, in, The coating (30) comprises at least one 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) oxide, Sc2O3, Y2O3, carbon, carbon black, Ca 10 (PO4)6(OH)2, polyimide, PMDA-ODA, PMDA-DAH, 3-aminopropyltrimethoxysilane coupling agent.

12. The structured substrate (1) according to any one of the preceding claims, wherein: 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 Wherein, the flat substrate (10) comprises at least one of the following components: A SiO2 content of at least 30 wt%, preferably at least 50 wt%, more preferably at least 80 wt%.

13. The structured substrate (1) according to any one of the preceding claims, in, The structured substrate (1) comprises a plurality of through holes (20) penetrating the material of the flat substrate (10), each forming an inner wall surface surrounding a corresponding through hole (20) and connecting the two opposite flat surfaces (12, 14) of the flat substrate (10), and / or The through hole (20) or at least one of the through holes (20) when there are multiple through holes (20) has a non-mirror-symmetric and / or non-circular cross-section, preferably including one or more rectangular portions, for example, in an L-shape.

14. A method for manufacturing a structured substrate (1) according to any one of the preceding claims, comprising: providing a flat substrate (10), preferably comprising a glass material and having two opposing flat surfaces (12, 14), wherein at least one through hole (20) penetrates through the material of the flat substrate (10) to form an inner wall surface surrounding the through hole (20) and connecting the two opposite flat surfaces (12, 14), Depositing a coating (30) having light absorption and / or light reflection function onto the flat substrate (10) to cover at least a portion of the inner wall surface of the through hole (20); and One or both of the planar surfaces (12, 14) of the planar substrate (10) is processed, preferably polished, to remove the coating covering the planar surfaces (12, 14) so ​​that one or both of the planar surfaces (12, 14) is free of the coating (30).

15. Method for producing a structured substrate (1) according to the preceding claim, in, The coating (30) is deposited on the flat substrate (10) 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).

16. Use of the structured substrate (1) according to any one of claims 1 to 13 for aligning the structured substrate (1) relative to another element, in, Preferably, when observing one of the flat surfaces (12, 14) of the structured substrate (1) in a top view, the coating (30) covering the inner wall surface is visible, which forms an outline around the through hole (20) in a side view, and Therein, preferably, the position of the contour around the through hole (20) is compared with a defined position on the other element.

17. Use of a structured substrate (1) according to the preceding claim, in, Preferably, in the xy plane, the position error between the contour around the through hole (20) and the defined position on the other element is reduced to less than 2 μm, preferably less than 1 μm, more preferably less than 0.1 μm, even more preferably less than 50 nm, and / or wherein the position error between the contour around the through hole (20) and the defined position on the further element is reduced to less than 20 μm, preferably in the z direction, more preferably over the entire area of ​​the substrate, and / or Therein, the structured substrate (1) and / or the further element comprise marks introduced by ion beam processing, wherein, preferably, these marks are used to align and / or assist in aligning the structured substrate (1) relative to the further element.

18. Use of a structured substrate (1) according to any one of claims 1 to 13 for producing a microsystem, preferably a micro-optical system, in, Preferably, the micro-optical system comprises a plurality of layers, and at least one of the layers is configured as the structured substrate (1), Preferably, stray light in the microsystem is reduced by covering a coating (30) on the inner wall surface of the through hole (20), the through hole penetrating the material of the flat substrate (10) of the structured substrate (1).

19. A component comprising a layer structure having two or more layers, wherein: At least one of the layers is a structured substrate (1) according to any one of claims 1 to 13.

20. The assembly according to 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 mark of the other substrate layer is aligned with the at least one through hole (20) of the structured substrate (1).

21. An assembly comprising at least three layers, in sequence 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. A beam dump comprising a structured substrate (1) according to any one of claims 1 to 13 and connected thereto a further substrate comprising at least one blackened and / or roughened surface.

23. A stray light filter element, comprising the 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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