Glass element with structured walls and method for manufacturing same - Patent Application 20070122997

Abstract

The present invention has a thermal expansion coefficient of 10 × 10 -6 K -1 The present invention relates to a flat glass element having the following vitreous material and two opposing surfaces. The glass element further comprises at least one recess penetrating the glass of the glass element, the recess having a recess wall extending around the recess and bordering the two opposing surfaces. The recess wall has a structure with a number of mutually bordering rounded dome-shaped depressions. The depressions and the ridges surrounding the depressions form the roughness of the recess wall. The recess wall has an average roughness value (Ra) of 5 μm or less, preferably 3 μm or less, and preferably 1 μm or less. The present invention also relates to a method for producing a flat glass element having a structured wall, in which the structure or roughness of the recess wall is adjusted in a targeted manner by setting laser parameters.

Description

[Technical Field]

[0001] The present invention relates to a plate-shaped glass element having a thermal expansion coefficient of 10 × 10 -6 K -1 The present invention relates to a plate-shaped glass element having the following glassy material, two opposing surfaces, and a recess extending through the glass of the glass element and having a structured recessed wall. The present invention further relates to a method for manufacturing a plate-shaped glass element having a structured wall, wherein the structure of the recessed wall is adjusted as intended by setting laser parameters.

[0002] The precise structuring of glass is attracting considerable interest in many application fields. Among these, glass substrates are used in camera imaging, particularly 3D camera imaging, electro-optics (e.g., LEDs in microfluidics), optical diagnostics, and sensor technology (e.g., pressure sensor technology and diagnostic technology). Such application fields include, for example, optical sensors, camera sensors, pressure sensors, light-emitting diodes, and laser diodes. In these cases, glass substrates are almost always used as components in the form of thin wafers or glass films. To enable the use of such glass substrates in increasingly miniaturized industrial applications and components, precision in the range of several micrometers is required. Here, processing of glass substrates refers to the structuring of any form of holes, cavities, and openings introduced within or through the glass substrate, as well as the substrate surface. Therefore, it is necessary to introduce structures in the range of several micrometers into the substrate.

[0003] Furthermore, in order to enable the use of glass substrates in a wide range of application fields, it is desirable that processing does not leave any damage, residue, or stress on the edges or volume of the substrate. Moreover, it is desirable that the manufacturing method for such substrates enables the most efficient manufacturing process possible.

[0004] Various methods can be used to structure the glass substrate, for example, by creating holes or openings.

[0005] Established methods include water blasting and sandblasting with appropriate masks, as well as ultrasonic vibration lapping. However, these methods are limited to small structures in terms of scaling, typically around 400 μm for ultrasonic vibration lapping and a minimum of 100 μm for sandblasting. In water blasting and sandblasting, mechanical ablation generates stress in the glass, resulting in spalling at the edges of the holes. Essentially, neither of these methods can be used for structuring thin glass. Because these methods are performed in the range of several hundred μm, this particularly affects not only the dimensions of the formed holes, cavities, and openings, but especially the surfaces created on the substrate. Therefore, the aforementioned methods are not suitable for forming microstructures on the substrate.

[0006] For this reason, the use of laser sources for structuring various materials has become established in recent years. A wide variety of solid-state lasers with infrared wavelengths (e.g., 1064 nm), green wavelengths (532 nm), ultraviolet wavelengths (365 nm), or ultrashort wavelengths (e.g., 193 nm, 248 nm) make it possible to introduce smaller structures into glass substrates than is possible with the mechanical methods described above. However, because glass has low thermal conductivity and is easily broken, laser processing can generate a high thermal load on the glass when creating very fine structures, which can lead to critical stress and result in microcracks and distortion in the edge regions of holes. Furthermore, even when using a fine laser beam with a diameter of only a few micrometers, generating a large-area structure on the substrate surface requires a great deal of effort. For this reason, this method is only suitable to a limited extent for industrial production of substrates where structuring of the surface of the aperture region is required.

[0007] This is particularly true for components and substrates that require suitability for specific applications. For example, glass substrates for microfluidic cells require particularly smooth surfaces within the flow path to minimize fluid resistance at the flow path walls. Another application area is electro-optic transducers that utilize customized glass spacers. These photoelectric transducers contribute to the enclosing and protection of electromagnetic transducers / emitters / receivers, enabling adjustment of predetermined spacings between various active and passive components, or specifically protecting delicate components. Special structuring of the substrate's aperture surface is necessary to optimally fix or even insulate these delicate components within the substrate or spacer's opening. Furthermore, special optical properties of the substrate are often required, such as improved photoconductivity, which can be achieved through a predetermined structure of the aperture surface that refracts light in a specific manner.

[0008] However, such structures cannot be generated by known methods. As mentioned above, polishing methods cannot create microstructure openings, and therefore, it is impossible to adjust the opening surfaces of the substrate's microstructure as desired. While known laser methods can achieve microstructures in the form of continuous openings to some extent, the laser beam primarily "pierces" the substrate, and therefore cannot similarly process substrate surfaces extending parallel to the laser beam. Furthermore, reprocessing the opening surfaces of each opening in the substrate with a laser beam is extremely time-consuming and costly, making it uneconomical. Moreover, such opening processing can only be performed within a limited range due to the angle of incidence of the laser.

[0009] Therefore, the present invention is based on the problem of providing a substrate having a specially structured opening surface and a method for manufacturing the substrate. This problem is solved by the subject matter of the independent claim. Advantageous variations are shown in their respective dependent claims.

[0010] Therefore, the present invention relates to a thermal expansion coefficient of 10 × 10 -6 K -1The present invention relates to a plate-shaped glass element having a glassy material and two opposing surfaces. The glass element further has at least one recess, which connects the two surfaces, opens to these surfaces, and penetrates the glass of the glass element. The recess has a recess depth, which is lateral to at least one of the surfaces of the glass element, preferably perpendicular, and corresponds to the thickness of the glass element. The recess has a recess wall, which extends around the recess and is in contact with the two opposing surfaces. The recess wall has a structure comprising numerous mutually contacting rounded, dome-shaped depressions. The roughness of the recess wall is formed by these depressions and the surrounding ridges. The recess wall has an average roughness value (Ra) of 5 μm or less, preferably 3 μm or less, preferably 1 μm or less, and particularly preferably 500 nm or less. However, according to a further embodiment, the wall has minimal roughness. In particular, the average roughness of the recess wall is at least 50 nm.

[0011] Because the concave walls of glass elements are particularly smooth, glass elements are suitable for use in the field of microfluidics. Here, the concave may be formed as a long fluid channel through which fluid can flow with almost no obstruction. In this case, it is also possible for the two surfaces to extend parallel to each other. This has the advantage that multiple glass elements can be stacked in parallel in a planar manner, and no misalignment occurs in such an arrangement. In this way, multiple glass elements can be stacked in a sandwich structure. This is particularly necessary in microfluidic cells, in which fluid is usually guided into a flow path by stacking three or more components, with two surfaces of the components positioned above / below the flow path forming the boundary of the flow path.

[0012] In a particular embodiment, the average roughness value (Ra) of the concave wall and / or outer wall is at least 50 nm, advantageously 0.2 μm or more, preferably 0.4 μm or more, and preferably 0.5 μm or more. Such low roughness not only enables application in microfluidics but also allows for the achievement of special optical properties. This is especially true when the roughness is in the range of 5 μm to 0.2 μm. For example, when Ra is 5 μm, the surface of the concave wall of the glass element has lower gloss than when Ra is 0.2 μm.

[0013] Advantageously, the dome-shaped depression has a depth of less than 10 μm, preferably less than 5 μm, and preferably less than 2 μm, where the depth is determined by the difference between the center of the depression's base and the central peak of the surrounding ridge. In the spirit of this invention, "dome-shaped" is understood to mean that the concave wall has a curved portion, this curved portion appears concave, the depression is particularly in the direction of the glass of the glass element, and the curved portion can project in a domed shape onto the glass element without being limited to a specific cross-section. Advantageously, the roughness of the concave wall is determined by the depth of the dome-shaped depression. This means that, in the spirit of this invention, the average roughness value is determined by the depth of the depression. Therefore, if the depth is less than 10 μm, the average roughness value is also less than 10 μm. It is also conceivable that the depth of the depression may be greater than 0.2 μm, preferably greater than 0.4 μm, and preferably greater than 0.5 μm. Because crack growth is hindered by uneven surfaces, especially curved sections, dome-shaped depressions prevent crack formation and crack propagation.

[0014] The dome-shaped depressions may all have a nearly uniform depth, or they may have different depths, for example. It is also possible for the dome-shaped depressions to be arranged with staggered heights. This means that some depressions are offset from others, particularly from the virtual center plane of the recess wall in a direction perpendicular to this plane. Here, the depressions may be regionally offset from the virtual center plane of the recess wall, where regional means that these are multiple depressions offset by similar amounts. Advantageously, the dome-shaped depressions are offset by an amount of less than 0.6 μm, preferably less than 0.4 μm, and preferably less than 0.2 μm. Such regions may be formed as dots or stripes, for example, stripes, in which case the stripes may be oriented laterally or parallel to the surface of the glass element. In this way, ripples may be formed on the recess wall, and these ripples may be oriented laterally and / or parallel to the surface of the glass element. Such ripples can improve the retention of, for example, members placed in the depressions of the glass element or glass substrate.

[0015] In one advantageous embodiment, the cross-sectional or lateral dimensions or diameter of the dome-shaped recess are less than 20 μm, preferably less than 15 μm, and preferably less than 10 μm. However, some recesses may have a diameter or cross-section of less than 60 μm, preferably less than 50 μm, and preferably less than 40 μm. By skillfully selecting the size and dimensions of the recess, for example, the friction and resistance of the member or fluid against the recess wall can be determined, so that the member can be better secured or the fluid can flow better through the recess. Here, the dome-shaped recess may have at least one of the following shapes: circular, elliptical, worm-shaped, or elongated and rounded by, for example, multiple integrated recesses, polygonal, for example, hexagonal. Furthermore, the edges may be formed as polygonal boundaries between each recess. In this case, the average number of angles of the recess boundaries may be advantageously less than 8, advantageously less than 7, and particularly 6. This feature arises when the area occupied by the majority of the dome-shaped recess is convex in a mathematical sense. By setting the appropriate shape of the recess, the recessed wall or glass element can be / is already better suited to a particular application.

[0016] It is also advantageous if the glass element has an outer wall that extends around the glass element and connects two surfaces to each other, and the outer wall has a structure with a number of mutually contacting, rounded, dome-shaped recesses. In this case, the outer wall can have features corresponding to the concave wall embodiment described above. In this way, the glass element itself can also be positioned so as not to slip within another component, for example, by an outer wall that is particularly rough.

[0017] It is also possible that the recessed wall and / or outer wall forms a rounded edge. In the spirit of the invention, this is understood to mean that one or more surfaces of the recessed wall and / or outer wall are structured roughly or throughout the entire surface. In other words, one or more surfaces of the recessed wall and / or outer wall have a continuous and uninterrupted structure of dome-shaped recesses and / or ridges positioned between the recesses. As a result, the glass element is better protected against microcracks as well, because the recessed wall and / or outer wall is effectively protected from or minimizes crack growth.

[0018] In the spirit of the present invention, this is understood to mean that one or more surfaces of the recessed wall and / or outer wall are structured, either rough or over the entire surface. In other words, 80%, 90%, particularly preferably 95%, or even 98% of one or more surfaces of the recessed wall and / or outer wall have a continuous and uninterrupted structure of dome-shaped recesses and / or ridges positioned between the recesses. In this way, the method according to the present invention makes it possible to manufacture a number of small parts having at least one structured outer wall and optionally at least one or more structured recessed walls, and connected to a retaining part, particularly a retaining part around a frame, by one or more bridge-like connections. When the parts are used, the bridge-like connections are separated from the retaining part by, for example, a classical fracturing process, optionally combined with the introduction of a predetermined fracturing point, which is performed, for example, by filamentation along the target part contour over the entire bridge.

[0019] Furthermore, the transmittance of visible light in the wavelength range of 300 nm to 1000 nm through the structured outer wall and / or concave wall and the glass element, and preferably through a second wall located on the opposite side of the concave wall and / or outer wall, is 80% or more, preferably 85% or more, and preferably 90% or more, in which case the direction of the light may be oriented perpendicular to the concave wall and / or outer wall and parallel to at least one face of the glass element. In this case, the optical path may be arranged to cross at least one, preferably two, walls or faces, of which at least one, optionally both, have a dome-shaped recess. Such high transmittance provides particularly high optical quality to the glass element or concave wall. As a result, the glass element is particularly suitable for optical applications and can be used, for example, as an optical component or light guide.

[0020] In one embodiment, it may be further assumed that concave walls and / or outer walls having an average roughness value of 1 μm or more have a lower reflectivity than those having an average roughness value of 1 μm or less. In this case, the concave walls and / or outer walls can exhibit a decrease in reflectivity as the average roughness value increases. For example, a concave wall and / or outer wall with an average roughness value of 0.5 μm can have approximately twice the reflectivity of a wall with an average roughness value of 1.4 μm. Therefore, by selecting a special roughness value for the concave walls and / or outer walls, the glass element can be made particularly well suited to specific optical applications. Thus, a concave wall with high roughness can be easily distinguished from a concave wall with low roughness by an image processing device due to its scattering behavior with respect to visible light, and can therefore be used, for example, for the alignment of the glass element as a whole.

[0021] It is often assumed that the roughness of the recessed wall and / or outer wall is formed anisotropically, in which case the anisotropy can be expressed as parameter A. In this case, A is the square of the quotient, which is formed from the average value of the average roughness (Ra) of three 30 μm wide measuring bands oriented parallel to a certain side surface of the glass element and the average value of the average roughness (Ra) of three 30 μm wide measuring bands oriented perpendicular to this side surface of the glass element. In other words, the quotient is formed from the average value of the average roughness of three measuring bands extending along the edge surface of the recess and the average value of three measuring bands extending perpendicularly thereto. Thus, the latter perpendicularly extending measuring bands extend from one side surface to the opposite side surface. In particular, this anisotropy may be 1 or less, preferably 0.8 or less, and preferably 0.6 or less. Here, the side surface in the spirit of the present invention can be understood as at least one of the two opposing surfaces of the glass element. Anisotropy may be formed by the displacement of ripples or dome-shaped depressions. In this case, the ripples or anisotropically formed roughness allow other components, such as electrical components, to be positioned in the depressions, and these components are protected from displacement due to increased friction against the depression walls when they move along the depression walls, especially when they move perpendicular to the surface of the glass element. In this way, components positioned in the depressions remain firmly fixed in the depressions, even when vibrations occur.

[0022] Also, the roughness of the concave wall and / or the outer wall is anisotropically formed, and the anisotropy is represented as parameter A, where A is the square of a quotient, and this quotient is the average value of the average roughness values (Ra) of three measurement bands with a width of 30 μm oriented parallel to a certain side surface of the glass element, and the average value of the average roughness values (Ra) of three measurement bands with a width of 30 μm oriented perpendicular to this side surface of the glass element. It is also assumed that the anisotropy is 1 or more, preferably 2 or more, preferably 3 or more. In this embodiment, since the corrugations may be oriented perpendicular to the glass surface, due to the anisotropically formed roughness, when other components in the recess, such as electrical components, move along the concave wall, especially when moving in a direction parallel to the surface of the glass element, it is possible to be protected from displacement with an increase in friction against the concave wall. On the other hand, since the mobility of the component is enhanced by the corrugations arranged perpendicular to the glass surface, the component can be displaced better. This is advantageous when the component repeatedly receives mechanical loads, such as in the case of a pressure sensor, and the mobility of the component within the glass element can protect both the component and the glass element from increased wear.

[0023] Therefore, overall, in one embodiment, the anisotropy (A) is - greater than 1, - preferably greater than 1.5, - or even greater than 4, or - less than 1 it may be advantageous.

[0024] Furthermore, it is also possible for the anisotropy (A) to be greater than 8, 9 or 10. In such embodiments, the corrugations can be particularly prominent in terms of strength.

[0025] In a further advantageous embodiment, the roughness of the concave wall and / or the outer wall is formed direction-dependently, and in this case, the roughness appears differently in at least a certain section, and the section is - Oriented laterally with respect to the depth of the recess or at least one surface, - Oriented parallel to the depth of the recess or at least one surface, In this case, the difference in the average roughness values ​​of the sections is less than 4 μm, preferably less than 2 μm, preferably less than 1 μm. However, direction-dependent roughness may be formed, for example, by dome-shaped depressions offset relative to the virtual center plane of the concave wall. Direction-dependent roughness allows for the precise placement of air chambers between the concave wall and the component, for example, to improve thermal insulation or electrical insulation. Furthermore, cleverly selected anisotropic structures, particularly ripples, can allow fluids to penetrate more effectively into channel-shaped depressions, for example, when the ripples are oriented along the direction of fluid flow, or perpendicular to the flow direction, especially when slower flow is desired.

[0026] In one advantageous embodiment, the glass element can have a thickness greater than 10 μm, preferably greater than 15 μm, preferably greater than 20 μm, and / or less than 300 μm, preferably less than 200 μm, preferably less than 100 μm. However, it is also possible for the thickness to be greater than 300 μm, or less than 10 μm, preferably less than 4 mm, preferably less than 2 mm, preferably less than 1 mm. Such thin glass can be structured very finely and without the risk of breakage by the methods described herein. Furthermore, the glass element may be formed to be flexible due to its small thickness and therefore bendable. Because other bonding forces often play an important role due to its small thickness, the glass element may also be formed to have higher mechanical stability against externally applied mechanical stress. These advantages allow the glass element to be used, for example, in IC packages, biochips, sensors, camera imaging modules, and diagnostic technology devices.

[0027] In other embodiments, glass elements with thicknesses ranging from 300 μm to 3 mm, and in special cases up to 6 mm, that do not deform or deform only slightly under the application of force, can also be used.

[0028] In further embodiments, the glass element has a lateral dimension greater than 50 mm, preferably greater than 100 mm, preferably greater than 200 mm and / or less than 500 mm, preferably less than 400 mm, preferably less than 300 mm. Small glass members, each having, for example, one or more recesses, can then be cut from such a glass element. According to one further embodiment, such small glass elements or glass members may have a lateral dimension of up to 5 mm, advantageously up to 2 mm. Such dimensions allow the glass element to be optimally used as a component for microtechnology.

[0029] In a further advantageous embodiment, the glass of the glass element is composed of the following components: - SiO2 content of at least 30% by weight, preferably at least 50% by weight, particularly preferably at least 80% by weight, - Maximum TiO2 content of 10% by weight It includes at least one of the following.

[0030] Ideally, the glass in glass elements is formed as borosilicate glass. Such glass possesses particularly high thermal stability, transparency, and chemical and mechanical stability, and is therefore very suitable for a wide range of applications, such as optical and electronic applications.

[0031] The problem can also be solved by a plate-shaped glass element having a structured wall, or by a method for manufacturing a plate-shaped glass element according to at least one of the embodiments described above. The glass element has a thermal expansion coefficient of 10 × 10 -6 K -1The following glassy material and two opposing surfaces are provided in this method. - Provide glass elements, - A laser beam from an ultrashort pulse laser is directed onto one of the surfaces of a glass element, and this laser beam is focused to a long focal point within the glass element by a focusing optical system. At that time, the irradiation energy of the laser beam generates numerous filamentous channels within the volume of the glass element, the depth of which the channels extend laterally with respect to the surface of the glass element, and the channels are arranged with spacing between them. - The glass element is exposed to an etching medium, and the glass of the glass element is removed by the etching medium at an ablation rate. In this process, the channel is widened by the etching medium, forming a recess with a structured recessed wall. The recessed wall extends around the periphery of the recess, is in contact with two opposing surfaces, and has a structure with numerous mutually contacting rounded, dome-shaped depressions. This structure creates the roughness of the recessed wall. Here, the recessed wall can also be understood as the inner edge of the recess.

[0032] In a preferred embodiment, the filamentous channels are arranged along a closed contour which can be any two-dimensional shape in principle. In a preferred embodiment, the contour follows regular two-dimensional geometric elements such as circles, ellipses, rectangles, squares, or polygons, so that after the completion of the structured glass substrate, the recesses according to the present invention can function as housings for, for example, electronic components.

[0033] By adjusting the laser parameters, it is advantageous to control the structure or roughness of the concave walls to the desired extent, thereby reducing the average roughness value (Ra) of the concave walls to 5 μm or less, preferably 3 μm or less, and preferably 1 μm or less. However, the average roughness value is advantageously at least 50 nm.

[0034] In this way, recesses and / or outer walls of different roughness can be generated on the substrate, wherein the difference in roughness between the recesses and / or outer walls is at least 0.5 μm, preferably 1 μm, or particularly preferably 2 μm. For example, multiple recesses of the same or different roughness for a part can be introduced into the substrate along with additional recesses of higher roughness to align the part as a whole in a reference system. In a further embodiment, the recesses for the part have anisotropic roughness, which can therefore ensure not only optimal alignment but also ideal placement of the part in the recesses during subsequent application processes.

[0035] This method can also be used to manufacture glass elements according to the embodiments described above, thereby achieving the aforementioned advantages. In this case, this method is particularly well suited to industrial manufacturing processes because it makes it possible to simultaneously manufacture a number of recesses in multiple glass elements. In a first process step, at least one glass element is provided, in particular without any recesses. In a further, particularly second step, at least one, but advantageously more, and especially more preferably many, damages, particularly in the form of filamentous channels, can be generated in the glass element, ideally forming holes in the glass element through the damage / channels, which are advantageously expanded in the subsequent etching process, such that the channels integrate and thereby allow individual parts of the glass element to be separated from the glass element, thus generating recesses.

[0036] To this end, advantageously, by generating multiple damages / channels adjacent to one another, a series of recesses forms a larger, ideally structured form of the resulting recess. The damage / channels have their longitudinal direction extending laterally to at least one face of the glass element, ideally both faces. In this case, the channel penetrates the glass element perpendicularly from one face, particularly from this face, to the other face positioned opposite it, thus penetrating both faces.

[0037] Damage / channels are generated within the glass element by at least one laser beam of an ultrashort pulse laser. Laser-induced recess generation is advantageously based on the following multiple steps: - A laser beam from an ultrashort pulse laser is directed onto one of the surfaces of the glass element. This laser beam can be focused to a long focal point within the glass element using a focusing optical system. In this case, the emission wavelength can be selected such that the glass element becomes substantially transparent, i.e., the transmittance is greater than 0.9, preferably greater than 0.95, and particularly preferably greater than 0.98.

[0038] - An ultrashort pulse laser irradiates a glass element with one or more pulses or pulse groups (so-called burst pulses), in which case, advantageously, the interaction between the electromagnetic field of the high-power laser pulse and the glass element initiates nonlinear absorption of the laser energy, which advantageously causes filamentous damage (particularly in the form of substantially cylindrical channels) within the material of the glass element at long focal positions, and this filamentous damage expands to form a channel.

[0039] - In this way, a number of channels are generated, and their arrangement, particularly on or within the glass element, is selected such that a number of channels arranged adjacent to one another form the contour of the resulting recess. In this case, the channels can be spaced apart from one another.

[0040] A preferred laser source according to the present invention is a neodymium-doped yttrium aluminum garnet laser (Nd:YAG laser) with a wavelength of 1064 nanometers. This laser source is, for example, (1 / e 2 A raw beam with a diameter of 12 mm can be generated, and a biconvex lens with a focal length of 16 mm can be used as the optical system. If necessary, the raw beam can be generated using a suitable beam shaping optical system, such as a Galilean telescope. The laser source operates at repetition frequencies of 1 kHz to 1000 kHz, advantageously 2 kHz to 100 kHz, and especially preferably 3 kHz to 200 kHz. In this case, this repetition frequency and / or scanning speed can be selected so that the desired distance between adjacent damage / channels is achieved.

[0041] As a beam source, other variations of the Nd:YAG laser, such as wavelengths of 532 nm or 355 nm produced by frequency doubling (SHG) or frequency tripling (THG), or even a Yb:YAG laser (emission wavelength 1030 nm), can be appropriately used.

[0042] Furthermore, the laser pulse can be divided into multiple single pulses, which may be less than 10, preferably less than 8, preferably less than 7, and / or greater than 1, preferably greater than 2, and preferably greater than 3. These single pulses can be combined into pulse packets, so-called bursts, and are particularly emitted as consecutive laser pulses. Advantageously, since these single pulses are directed to the same location or place on the glass surface, the damage from consecutive single pulses is further extended, preferably creating a channel that penetrates the entire thickness or volume of the glass element.

[0043] Advantageously, by skillfully selecting the number of single pulses within a single pulse packet, the resulting concave / channel walls can be influenced, and in particular, the structure of the concave / channel walls can be precisely controlled. Since the total output of the laser pulse is divided into multiple single pulses in a single pulse packet or burst, each pulse has lower energy compared to a single laser pulse. Therefore, the energy of each single pulse decreases as the number of single pulses increases. However, it is desirable that the pulse energy of the single pulses be flexibly adjustable, in particular, that the pulse energy remain substantially constant, increase, or decrease, and that, advantageously, the first single pulse of a burst or pulse packet may have either the lowest or highest energy of the single pulses. Furthermore, when an ultrashort pulse laser is operated in burst mode, the repetition frequency may be the repetition frequency of the burst emission. In addition, since the single pulses strike the surface or inside the damage of the glass element at time lags, each single pulse alters the previously generated state of the concave / channel walls. In this way, by selecting the number of single pulses in a burst, concave / channel walls can be structured and altered as desired.

[0044] Here, it is particularly advantageous that the typical output power of the laser source is in the range of 20 to 300 watts. To obtain damage / channeling, according to an advantageous development of the present invention, pulse energies of pulses and / or pulse packets greater than 400 microjoules are used, and more advantageously, total energies greater than 500 microjoules are used. The preferred pulse duration of the laser pulse is in the range of less than 100 picoseconds, preferably less than 20 picoseconds.

[0045] However, it may be assumed that pulse durations of less than 15 ps, preferably less than 10 ps, ​​and preferably less than 5 ps are selected. Advantageously, an additional pulse duration of 1 ps is used to produce smooth concave / channel walls, particularly those with low roughness or low average roughness values. Here, roughness can be increased with increasing pulse duration. One possible reason for this is the thermal behavior of the glass. This is because, with longer pulse durations, the glass is exposed to the laser energy for a longer period, and consequently to the heat of the generated laser beam, which can damage glass, especially that with low thermal stability, for example, by expansion. Therefore, by precisely selecting the pulse duration, and ideally the roughness of the concave / channel walls, the glass of the glass element can be damaged in a specific manner. This also means that glass with a low coefficient of thermal expansion will be less damaged than glass with a high coefficient of thermal expansion. Here, the pulse duration is substantially independent of whether the laser operates in single-pulse mode or burst mode. Pulses in burst mode typically have similar pulse lengths to pulses in single-pulse mode. Here, the burst frequency can be in the range of 15MHz to 90MHz, preferably in the range of 20MHz to 85MHz, for example, 50MHz.

[0046] Furthermore, it is also advantageous when the channels are spaced apart from each other, with this spacing being less than 20 μm, preferably less than 15 μm, preferably less than 10 μm and / or greater than 1 μm, preferably greater than 2 μm, and preferably greater than 3 μm. However, the spacing between channels can also be greater than 5 μm and / or less than 100 μm, preferably less than 50 μm, and preferably less than 15 μm.

[0047] Regardless of the channel diameter, the spacing between adjacent channels can also be called the pitch, that is, for example, the spacing between laser pulses emitted simultaneously or, in particular, consecutively with staggered spacing between them. Here, this spacing is measured from center to center of a channel, or from the center of one pulse to the center of an adjacent pulse. The choice of channel spacing can affect roughness, particularly because the sections between channels have dimensions corresponding to the thickness of the glass element and the spacing between channels, and do not need to be intentionally processed with a laser, but are only subjected to the subsequent etching process.

[0048] Therefore, two distinct regions can be created: a region where the surface is structured by the laser and, preferably, the etching medium, and a region where the surface is structured only by the etching medium, and the glass element is exposed to this etching medium after the channel is formed. In this way, a direction-dependent or anisotropic roughness, particularly of the concave wall, can be created. In this case, preferably, the region between the channels can have a different roughness from the region of the channel, and the longitudinal extent of both regions extends preferably parallel to the laser beam or laterally, and especially perpendicularly, to at least one surface of the glass element, thereby ideally forming an anisotropy greater than 1.

[0049] Further, and more advantageously in the final step, the glass element is exposed to an etching medium, including channels formed within the glass element, to remove the glass from the glass element at a controllable ablation rate, thereby expanding the channels with the etching medium, and especially the ablation that results. In this way, one recess, and preferably multiple recesses, having a structured recessed wall can be formed. In this case, the ablation can typically generate a dome-shaped depression of the recessed wall and / or outer wall. It is advantageous that the etching medium is filled into a container, such as a tank, pot, or tub, and that one or more glass elements are subsequently held or immersed in this container or in the etching medium, at least partially.

[0050] The etching medium may be in gaseous form, but is advantageously an etching solution. Therefore, according to one embodiment, etching is performed wet chemically. This is advantageous for removing glass components from the inner surface of the channel during etching. If the channel wall is configured particularly non-planar or planar, for example by selecting appropriate laser parameters, e.g., burst, pitch, and / or pulse duration, a depression can be added to the concave wall / channel wall by etching or wet chemical etching ablation or material ablation. This makes it possible to impart or create a concave wall with a particularly advantageous dome-shaped depression, which may have high or low roughness, as required.

[0051] It is assumed that acidic or even alkaline solutions will be used as etching solutions. Suitable acidic etching media include HF, HCl, H2SO4, ammonium difluoride, HNO3 solutions, or mixtures of these acids. Basic etching media include, for example, KOH or NaOH alkaline solutions. These are particularly effective in glass compositions with low alkali metal content because basic etching solutions are less likely to rapidly supersaturate in such glasses and can therefore retain their etching ability for much longer than in the case of strongly alkaline glasses. Therefore, it is ideal to select the etching medium used according to the glass of the glass element being etched. Accordingly, depending on the glass composition, an acidic etching medium can be selected to set a high ablation rate in silicate glass, or a basic, especially alkaline, etching medium can be selected to set a low ablation rate.

[0052] Etching is advantageously carried out at temperatures above 40°C, preferably above 50°C, preferably above 60°C and / or below 150°C, preferably below 130°C, preferably below 110°C, and especially below 100°C. This temperature allows for sufficient mobility of the glass ions or components of the glass element being dissolved from the glass matrix.

[0053] Another factor is time. For example, exposing a glass element to an etching medium for several hours, especially longer than 30 hours, can generally achieve high ablation. On the other hand, it is possible to limit ablation by exposing the glass element to the etching medium for less than 30 hours, for example, just 10 hours. In the best case, the ablation rate is selected so that the dome-shaped depression forms a shape that has the largest volume with the smallest perimeter or cross-section mathematically, especially a circular shape, or even a nearly hexagonal or polygonal shape. In this way, a uniform roughness of the concave wall can be achieved.

[0054] The present invention will be described in further detail below with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding elements. [Brief explanation of the drawing]

[0055] [Figure 1] This is a schematic diagram illustrating the generation of damage in a glass element by a laser. [Figure 2] This is a schematic diagram showing a glass element with multiple damages. [Figure 3] This is a schematic diagram showing the etching process for glass elements. [Figure 4] This is a schematic diagram showing the glass element after the etching process and the creation of recesses through partial separation. [Figure 5] This is an electron microscope image of the concave wall of a glass element. [Figure 6] This figure shows the measurement results of the roughness of the concave wall in relation to the pulse duration. [Figure 7] This figure shows the measurement results of the roughness of the concave wall relative to the burst. [Figure 8] This figure shows the measurement results of the roughness of the concave wall relative to the pitch. [Figure 9] This figure shows the measurement results of a highly isotropic concave wall surface with a pulse duration of 1 ps. [Figure 10] This figure shows the measurement results of a highly isotropic concave wall surface parallel to the laser with a pulse duration of 10 ps. [Figure 11] This figure shows the measurement results of a highly isotropic concave wall surface perpendicular to the laser with a pulse duration of 10 ps. [Figure 12] This figure shows the measurement results of a concave wall surface that does not exhibit clear isotropy at a pulse duration of 10 ps. [Figure 13] This is a schematic diagram illustrating the measurement of the transmittance of a concave wall. [Figure 14] This figure shows the results of the reflectance measurement of the concave wall.

[0056] Figure 1 schematically shows a glass element 1. This glass element 1 has two faces 2, which are positioned opposite each other such that the volume of the glass element is located between them, and the glass element 1 has a thickness D that defines the distance between these two faces 2. Here, these faces may be positioned parallel to each other. The glass element 1 further extends in the longitudinal direction L and the transverse direction Q. Advantageously, the glass element 1 also has at least one outer surface 4, which ideally completely encloses the glass element 1, and its height corresponds to the thickness D of the glass element 1. In this case, ideally, the thickness D of the glass element 1 and the height of the side surface 4 extend in the longitudinal direction L, and the faces of the glass element can extend in the transverse direction.

[0057] In the first process step, damage is generated within the volume of the glass element 1 by a laser 101, preferably an ultrashort pulse laser 101, particularly in the form of a channel 16 or damage 16 in the shape of a channel. To this end, the laser beam 100 is focused by a focusing optical system 102, for example, a lens that is not corrected for spherical aberration or a lens system in which spherical aberration is increased by the cumulative effect of individual elements, and directed onto the surface 2 of the glass element. By focusing the laser beam 100 onto a region within the volume of the glass element 1, particularly by long focusing, the energy of the irradiated laser beam 100 generates filamentous damage, which is further extended in particular to a channel 16, which is done, for example, by using a burst mode, in which damage or channel 16 is generated by multiple single pulses in the form of pulse packets.

[0058] To ensure optimal structuring of the surfaces of the recesses 10 generated in later process steps, it may be advantageous to set predetermined laser parameters precisely so that these surfaces are, so to speak, pre-treated when the damage and / or channels are generated. For this purpose, at least one of the following parameters can be precisely set: the pulse duration of the laser beam 100, which is advantageously in the picosecond or femtosecond range; the number of single pulses in a pulse packet or burst; the spacing between the emitted laser beams 100, i.e., the spacing between the generated damage / channels 16; the laser energy; or the frequency. Although not limited to this embodiment, the pulse packet frequency may be, for example, 12 ns to 48 ns, preferably about 20 ns; the pulse energy may be at least 200 microjoules; and the burst energy may be at least 400 microjoules. By appropriately selecting specific values ​​for these parameters, the roughness of the recess walls 11 of the generated recesses 10 can be set precisely as early as possible.

[0059] Advantageously, as shown in Figure 2, multiple channels 16 are generated in a further step, and by arranging them ideally adjacent to one another, the numerous channels 16 result in holes, and these holes or numerous channels 16 form the contour of the structure 17. In the best case, the structure 17 thus generated corresponds to the shape of the generated recess 10. That is, the spacing 18 and number of channels 16 are selected so as to form the contour of the generated recess. Here, the spacing 18 of the channels 16 corresponds to the laser pitch, i.e., the spacing 18 of the emitted laser beams 100.

[0060] Figure 3 shows further steps. After a number of channels 16 are generated in the glass element 1 by the laser 101, the glass element 1, preferably structured by the channels, is placed in the etching medium 200. For this purpose, the glass element is preferably detachably arranged on a holder 50, in which case the glass element 1 may simply rest on or be fixed to the holder 50. Here, the glass element 1 is held, preferably in, the etching medium 200, preferably in the etching solution, preferably in a container 202, by the holder 50, and more preferably immersed in it. Ideally, the container 202 has a material that is substantially durable to the etching medium 200 for this purpose. This means that, because the material of the container 202 is substantially durable, the etching medium 200 attacks or erodes the container material only to a very small extent, or because ions and atoms of the material of the container 202 remain substantially within the volume of the container 202 when in contact with the etching medium 200, the composition of the etching medium 200 does not ideally change upon contact with the container 202. However, it is possible that the composition of the etching medium 200 may be affected upon contact with the container, in particular, by container components released from the container 202, which can alter the etchability of the etching medium 200, thereby changing the ablation rate of the glass element ablation 70 in a desired direction. However, the ablation rate can also be altered by, for example, physically and / or mechanically induced motion of the etching medium 200, especially stirring by a magnetic stirrer, or by local temperature changes. Advantageously, the optimal ablation rate is achieved by keeping the etching medium 200 at a temperature of 40°C to 150°C.

[0061] Preferably, an acidic or alkaline solution is used as the etching medium 200, and an alkaline solution, such as KOH, is particularly used. Ideally, a basic etching medium 200 with a pH value >12 is used, for example, a KOH solution having a concentration of >4 mol / l, preferably >5 mol / l, particularly preferably >6 mol / l, but <30 mol / l. Although not limited to this embodiment, etching is advantageously carried out at an etching medium temperature of >70°C, preferably >80°C, particularly preferably >90°C, especially about 100°C, or below 160°C.

[0062] The ablation 70 or ablation rate can be adjusted, for example, by the time the glass element 1 is exposed to the etching medium 200. In this regard, the longer the glass element 1 remains in the etching medium 200, the greater the desired ablation 70. To make the channel wall or the wall of channel 16, which has been prestructured by the laser 100, into its desired structure, or the desired roughness of the resulting recess 10 or recessed wall 11, an ablation rate of less than 5 μm per hour is optimal. In particular, the desired average roughness value can also be achieved by the total etching time. For this purpose, an etching time of at least 12 hours is advantageous. However, the ablation may vary, for example, to about 34 μm with an etching time of 16 hours, 63 μm with 30 hours, and 97 μm with 48 hours.

[0063] Ideally, the ablation 70 and etching times are selected such that the material between adjacent channels is removed to the extent that the channels are integrated and a connected opening is created, particularly by the integration of channel 16, as schematically shown in Figure 4. The connected opening can take any other shape and / or contour, but is not limited to the example shown in Figure 4. The important point is that the integration of channel 16 creates a large opening within the glass element 1, and the integration of the channels exposes the inner portion 20 of the glass element 1 that was previously surrounded by channels, and this inner portion 20 can be detached or removed. In this process, a recess 10 with a concave wall 11 is created.

[0064] Ideally, the concave wall 11 has a uniform structure with a roughness or average roughness value set specifically as intended. However, it may also be advantageous if the concave wall 11 is formed anisotropically, for example by setting the ablation rate specifically as intended, and this is done in such a way that intermediate regions between channels are removed incompletely or partially, and therefore the concave wall 11 has such intermediate regions 30 and channel regions 31. By modifying the intermediate regions 30 and channel regions 31, ripples can be formed on the concave wall 11, or may be formed, and these ripples may advantageously create anisotropic or direction-dependent roughness of the concave wall 11.

[0065] In order to optimally adjust the structure or roughness of the concave wall, it can be assumed that at least one of the following relationships holds: - Burst × Pulse duration = constant - Pitch / Ablation = Constant

[0066] These relationships clearly show that laser parameters, particularly pitch and burst, or the number of single pulses in a pulse packet, have a significant impact on the roughness of the concave wall.

[0067] Figure 5 shows an electron microscope image of the channel section 31 of the concave wall 11. Numerous dome-shaped depressions 12 distributed on the concave wall 11 are clearly visible. Here, the depressions 12 are arranged in contact with each other, and ideally each depression 12 is surrounded by a ridge 13, which can suppress, for example, the growth of cracks. As can be seen in the photograph, the depressions 12 form a concave curvature, and since the curved portion of this curvature extends in the direction of the glass volume, the ridge 13 in particular is higher with respect to the central plane than, for example, the depression base 14. Here, the depression base 14 substantially forms the lowest point of the depression relative to the ridge 13, and advantageously, the ridge 13 forms the highest point, i.e., the highest line. However, the ridge 13 is formed very narrowly with respect to the curvature or curved portion.

[0068] Here, the depth of the dome-shaped depression may be 10 μm to 0.1 μm, and preferably 0.2 μm to 2 μm, because this depth substantially determines the roughness of the depression wall 11, and this depth corresponds in particular to the difference between the center of the depression bottom 14 and the ridge 13 surrounding the depression. In other words, the depth of the depression 12 substantially determines the average roughness value (Ra) of the depression wall 11. Other factors such as ripples and / or intermediate regions 30 also contribute to the average roughness value (Ra). In the best case, the average roughness value (Ra) is 0.2 μm to 4.5 μm.

[0069] Furthermore, the depressions 12 have a cross-section 15 that is advantageously 5 μm to 30 μm in size, particularly 10 μm to 20 μm. Here, the shape of the cross-section 15 or depression 12 may be polygonal. In this case, the edges 13 form the boundary between the depressions 12, and the edges 13 may also be angular due to the polygonal shape of the depressions 12. Ideally, the depressions 12 should be formed during the etching process such that a space-saving cross-section 15 with 5 to 8, preferably exactly 6, corners is formed, because such a shape mathematically provides the smallest perimeter while maximizing the volume, i.e., it approaches a circle. In particular, this allows for the setting of a uniform and consistent roughness, and thus the glass element can be adapted particularly precisely to its intended application.

[0070] Figure 6 is a graph showing the measured average roughness (Ra) on the concave wall 11 resulting from the combination of laser damage 16 introduction and subsequent damage expansion by etching to create channels 16. This graph shows the average roughness (Ra) generated by the above process against various laser parameters. Here, the average roughness (Ra) is plotted on the vertical axis, and the number of single pulses in a burst or pulse packet is plotted on the horizontal axis. The size or diameter of the measurement points represents the pitch, or the distance between pulses and channels. Furthermore, the right side shows the measured roughness at a pulse duration of 1 ps, and the left side shows the measured roughness at a pulse duration of 10 ps. The distribution of average roughness (Ra) clearly shows the correlation between roughness and pulse duration, number of pulses, and pulse interval.

[0071] As the graph shows, when the pulse duration is short, for example, 1 ps, the average roughness value (Ra) is lower and the surface of the concave wall 11 is smoother than when the pulse duration is long, for example, 10 ps. In particular, the graph shows that when the pulse duration is short, the influence of not only the pitch but also the burst or single pulse count is less than when the pulse duration is long. Therefore, when the pulse duration is long, about 10 ps, ​​the measured average roughness value (Ra) is particularly high, especially when the pitch and burst are high, in the range of approximately 1 μm to 2 μm. On the other hand, when the pulse duration is short, the average roughness value (Ra) is 1 μm or less, regardless of the pitch or burst. In other words, by shortening the pulse duration, particularly low roughness of the concave wall 11 can be achieved.

[0072] Figures 7 and 8 show the measured average roughness values ​​(Ra) of the recessed wall 11. However, the average roughness value (Ra) is shown against bursts, i.e., the number of single pulses (plotted on the horizontal axis in Figure 7; plotted on the vertical axis in Figure 8) and pitch, i.e., the interval between pulse packets (plotted on the vertical axis in Figure 7; plotted on the horizontal axis in Figure 8). Both figures show the measured roughness for a pulse duration of 10 ps. Here, the lines connecting the measurement points represent the glass ablation removed by the etching process. Figures 7 and 8 show the correlation between the possible roughness of the recessed wall 11 and / or the outer wall 11, and the pitch and bursts. Here, it is clear that the roughness or the measured average roughness value (Ra) is particularly high, for example, in the range of 3 μm or more, when the pitch is high, for example 12 μm or more, or when the burst is high, for example 7 or more. On the other hand, when the pitch is 6 μm or greater, even if the burst is very low, 1-2, the measured average roughness value (Ra) is relatively high, for example, greater than 1.5 μm. Since the measured curves extend substantially parallel and largely overlap, it can be concluded that ablation has only a slight effect on the roughness occurring on the concave wall 11 and / or outer wall 4. In effect, the roughness of the concave wall 11 and / or outer wall 4 can be adjusted by the selection of laser parameters, particularly pulse duration, pitch, and burst.

[0073] Therefore, it is clear that it is possible to produce particularly rough recessed walls 11 and / or outer walls 4 by a parameter range that provides at least one of the following parameters, or more favorably, a combination of the following parameters: - The pulse duration is long, for example, 1 or more, preferably 3 or more, and more preferably 5 or more. - The pulse packet (burst) has a large number of single pulses, for example, 7 or more. - The pitch is large, for example, 10 μm or larger.

[0074] On the one hand, it is possible to produce particularly smooth concave walls 11 and / or outer walls 4 with particularly low roughness values, in particular by a parameter range that provides at least one of the following parameters, preferably a combination of the following parameters: - The pulse duration is short, for example 5 or less, preferably 3 or less, and preferably 1 or less, - The number of single pulses in the pulse packet (burst) is 2 - 7, - The pitch is small, for example less than 15 μm.

[0075] However, in a further development of the method, in order to separate one or more inner parts 20, at least one small pitch, that is, the spatial interval between two collision points of the laser beam 100 on the glass element 1 or at least two channels 16, is at most 6 μm, preferably at most 4.5 μm, and / or the ablation is assumed to be 34 μm or more. In particular, in order to separate at least one inner part 20, a combination of a low pitch or a high pitch and a high ablation is advantageous, whereby the channels can be expanded to such an extent that the channels are connected during the etching process. This can be achieved by a sufficiently high degree of ablation.

[0076] Therefore, FIGS. 并 8 show that the selected laser parameters have a decisive influence on the roughness of the concave wall 11 depending on the behavior of the glass material, for example the coefficient of thermal expansion. Here, the coefficient of thermal expansion is 10×10 -6 K -1 The following glass is intentionally selected. Furthermore, the coefficient of thermal expansion is 0.1×10 -6 K -1 or more, preferably 1×10 -6 K -1 or more, particularly preferably 2×10 -6 K -1As described above, it may be advantageous if the glass has sufficient expandability to elicit a response to the laser energy. Although not limited to the embodiments presented, glass having an SiO2 content of 30% to 80% by weight and / or a TiO2 content of up to 10% by weight is particularly preferred in terms of processability.

[0077] Figures 9 to 12 show the measured surface of a concave wall 11 with direction-dependent roughness after 10 μm ablation in an etching bath in a measurement area approximately 800 μm wide and 750 μm high. Here, the width of the measurement area is parallel to the surface 2 of the glass element, and the measurement height is perpendicular to the surface of the glass element 1, and in particular parallel to the laser beam 100. The roughness or depth (in μm) of the depression 12 relative to the central surface of the concave wall 11 can be read from the scale at the right edge of the photograph.

[0078] Figures 9 and 10 show recessed walls 11 having roughness that extends anisotropically, particularly in a striped pattern parallel to the laser beam or perpendicular / transverse to the surface 2 of the glass element 1. In this case, the anisotropy coefficient A is advantageously greater than 1. This anisotropy is particularly pronounced when the pulse duration is short, about 1 ps, the burst is low, at 2, and the pitch is 10 μm, as shown in Figure 9. The dome-shaped depressions 12 are difficult to identify but clearly appear in a pattern, or are arranged facing each other as if in a pattern, and in particular are arranged in overlap with the direction of the laser beam such that the arrangement of the depressions 12 forms stripes that extend perpendicular / transverse to the surface 2 of the glass element. In this case, the depressions 12 have a rounded, possibly circular, cross-section.

[0079] As shown in Figure 10, the situation is different in the case of a concave wall 11 formed at 10 ps, ​​burst 1, and pitch 10 μm. Similar to Figure 9, the roughness is formed anisotropically, extending particularly parallel to the laser beam or perpendicular / lateral to the surface 2 of the glass element 1. However, the individual depressions 12 in this case are formed in a worm-like shape, which is advantageously spread along a direction parallel to the laser beam 100 and / or perpendicular / lateral to the surface 2 of the glass element 1. In the spirit of the present invention, the worm-like shape should be understood as the ridge portion 13 around the depression 12 forming an uneven height, with some areas having a height that may correspond to the depth of the depression, or at least significantly less than the height of most of the ridge portion 13 around the depression. When the height of at least one region of the ridge 13 is low in two or more adjacent depressions, these depressions 12 appear with a nearly uniform depth in the measurement image, resulting in a worm-like shape due to the continuous arrangement of individual depressions 12. Overall, it can be seen that the concave walls 11 are formed significantly coarser, and therefore less glossy or rougher, when using a pulse duration of 10 ps (Figure 10; average roughness value 0.50 μm) than when using a pulse duration of 1 ps (Figure 9; average roughness value 0.38 μm). Thus, the average roughness value (Ra) can be adjusted with particular precision by changing the pulse duration.

[0080] Figure 11 shows a recessed wall 11 having roughness formed anisotropically, preferably in a striped pattern extending laterally with respect to the laser beam 100 and / or parallel to the surface 2 of the glass element 1. In this case, the anisotropy coefficient A is preferably 1 or less. The recessed wall 11 in this case represents substantially two regions extending in a striped pattern, and since the depressions 12 in each region preferably have a uniform depth, these regions differ substantially in terms of depression depth. As a result, the grayscale values ​​of the measurement results, or the average roughness values ​​(Ra) of each region, are relatively uniform.

[0081] Figure 12 shows a concave wall 11 with an average roughness of 1.05 μm, generated with a pulse duration of 10 ps, ​​burst 2, and pitch of 3 μm. In this example, since the dome-shaped depressions 12 are distributed substantially uniformly on the concave wall 11, only slight or no anisotropy is formed. Advantageously, the cross-sections of the circular or elliptical depressions 12 also appear relatively similar, resulting in the formation of a uniform structure on the concave wall 11.

[0082] Figures 13 and 14 schematically show the setup for transmittance measurement and the measurement results for reflectance measurement. Advantageously, the glass element may be formed transparently, allowing transmission of visible light, or more broadly, light in the wavelength range of 300 nm to 1000 nm. The structuring of the recessed wall 11 and / or outer wall 4 produced by the previously described method has optical shaping properties that are advantageous in suppressing, for example, the speckle effect and other interference effects in laser diodes. For this purpose, the structure of the recess 12 or wall may be configured uniformly or anisotropically, for example, according to the shapes shown in Figures 9 to 12, in order to influence the light passing through. Advantageously, the glass element 1 is such that light can penetrate not only the recessed wall 11 and / or outer wall 4 but also the surface 2 of the glass element, and thus electromagnetic waves can be transmitted and received through the glass element 1.

[0083] Particularly advantageous is that, when the roughness (Ra) adjusted by the aforementioned method is 0.5 μm, the volume of the walls 11,4 and the glass element 1 can transmit more than 90% of the light in the wavelength range of 300 nm to 1000 nm. However, if it is desired to lower the transmittance of the walls 11,4, the average roughness value (Ra) can be adjusted to, for example, 1.4 μm, thereby transmitting only, for example, slightly more than 86% of the light, and reflecting more light in the wavelength range of 300 nm to 1000 nm.

[0084] This could be demonstrated in particular by the measurement setup schematically shown in Figure 13. Transmittance could be measured using an integrating sphere 81 and a light ray 80, for example, a light ray with a wavelength of 690 nm. In this case, the light ray 80 traversed the outer wall 4, which may be specially polished, over a volume of approximately 10 mm of the glass element 1, and passed through or penetrated the concave wall 11. Here, the concave wall 11 is positioned at or directly in front of the incident position of the integrating sphere 81. In this way, the light ray is scattered on the walls 11,4, and all angles can be detected by the integrating sphere 81. In order to determine the transmittance of the walls 11,4 independently of the volume of the glass element 1 and / or further walls, it is also conceivable to subtract the transmittance of the volume of the glass element 1 and / or the polished wall from the transmittance measurement result. To determine the transmittance of the glass element 1 and / or the volume of further walls, for example, the transmittance of the glass element may be measured so that light penetrates the surface 2 of the glass element 1, or the reflectance of the wall may be determined by reflectance measurement and then subtracted from the overall results of the transmittance measurement.

[0085] Figure 14 shows the results of reflectance measurements. Light was shone onto walls 11 and 4 using an optical waveguide or fiber sensor, and the light reflected by walls 11 and 4 in the wavelength range of 300 nm to 1000 nm was detected. Advantageously, the detected measurement results clearly show that the reflectance can be adjusted by the roughness of walls 11 and 4, or that a desired reflectance can be set based on the roughness. For example, it was found that the reflectance of light was significantly lower on the rough wall 11, which has an average roughness of, for example, 1.4 μm, than on the less rough or even smoother walls 11 and 4, which have an average roughness of, for example, 0.5 μm. [Explanation of Symbols]

[0086] 1. Plate-shaped glass element 2 sides 4. Exterior walls 10 recesses 11 Concave wall 12 Dome-shaped depression 13 Ridge section 14. Lower part of depression 15 Cross-section 16 channels / damage 17 Structure 18 corners 20 Inner part 30 Intermediate area 31 Channel Area 50 Holding part 70 Ablation 80 rays 81 Integrating sphere 90 Rough wall 91 Smooth wall 100 laser beams 101 Lasers / Ultrashort pulse lasers 102 Focusing optical system 200 Etching media 202 Container L (vertical direction) Q: Lateral direction D Glass element thickness

Claims

1. A flat glass element (1), the flat glass element (1) having a thermal expansion coefficient of 10×10 －６ K －１ a glass element (1) having a glass material below a thickness of two opposing faces (2) and at least one recess (10) connecting the two faces (2), opening into the faces (2) and penetrating the glass of the glass element (1), the recess (10) having a recess depth, the recess (10) extending transversely to at least one of the faces (2) of the glass element (1), the recess (10) depth corresponding to the thickness of the glass element (1), the recess (10) having a recess wall (10), The plate-shaped glass element (1) has a wall (10) extending around the recess (10) and in contact with the two opposing surfaces (2), the recess wall (10) having a structure with a number of mutually adjoining rounded dome-shaped depressions (12), the depressions (12) and ridges (13) surrounding the depressions (12) forming a roughness of the recess wall (10), the recess wall (10) having an average roughness value (Ra) of less than 3 μm, preferably less than 1 μm, particularly preferably at least 50 nm.

2. 2. The sheet glass element (1) according to claim 1, wherein the dome-shaped depression (12) has a depth of less than 10 μm, preferably less than 5 μm, preferably less than 2 μm, the depth being determined by the difference between the center of the depression bottom (14) and the central peak of the ridge (13) surrounding the depression.

3. 3. The sheet glass element (1) according to claim 1 or 2, wherein the cross section (15) or diameter of the dome-shaped depression (12) is less than 20 μm, preferably less than 15 μm, preferably less than 10 μm.

4. 4. The glass element (1) according to claim 1, wherein the glass element (1) has an outer wall (4), which extends around the periphery of the glass element (1) and connects the two faces (2) to each other, and the outer wall (4) has a structure with a number of mutually adjoining rounded dome-shaped depressions (12).

5. 5. The sheet glass element (1) according to claim 1, wherein the average roughness value (Ra) of the recessed wall and / or the outer wall is greater than 0.2 μm, preferably greater than 0.4 μm, preferably greater than 0.5 μm.

6. 6. The sheet glass element (1) according to claim 1, wherein the transmittance of visible light in the wavelength range from 300 nm to 1000 nm through the structured outer wall (20) and / or the recessed wall (10) and through the glass element (1) is more than 80%, preferably more than 85%, preferably more than 90%, in which case the light direction is oriented perpendicular to the recessed wall (10) and parallel to at least one face (2) of the glass element (1).

7. 5. The flat glass element (1) according to claim 4, wherein the roughness of the recessed wall (10) and / or the outer wall (4) is anisotropically formed, the anisotropy being expressed as a parameter A, where A is the square of the quotient formed from the average value of the average roughness values ​​(Ra) of three 30 μm wide measurement bands oriented parallel to a side of the glass element (1) and the average value of the average roughness values ​​(Ra) of three 30 μm wide measurement bands oriented perpendicular to the side of the glass element (1), and the anisotropy is less than or equal to 1, preferably less than or equal to 0.8, preferably less than or equal to 0.

6.

8. 5. The flat glass element (1) according to claim 4, wherein the roughness of the recessed wall (10) and / or the outer wall (4) is formed anisotropically, the anisotropy being expressed as a parameter A, where A is the square of a quotient formed from the average value of the average roughness values ​​(Ra) of three 30 μm wide measurement bands oriented parallel to a side of the glass element (1) and the average value of the average roughness values ​​(Ra) of three 30 μm wide measurement bands oriented perpendicular to the side of the glass element (1), and the anisotropy is 1 or more, preferably 2 or more, preferably 3 or more.

9. The roughness of the recessed wall (10) and / or the outer wall (4) is directionally dependent, and the roughness appears differently in at least certain sections, and the sections are - oriented transversely to said recess depth or to at least one face (2), or - oriented parallel to said recess depth or at least one face, 5. The sheet glass element (1) according to claim 4, wherein the difference in the average roughness values ​​of the sections is less than 4 μm, preferably less than 2 μm, preferably less than 1 μm.

10. The glass of the glass element comprises the following components: at least 30% by weight, advantageously at least 50% by weight, particularly preferably at least 80% by weight of SiO ２ content, - maximum 10% by weight of TiO ２ Content 10. The flat glass element (1) according to any one of claims 1 to 9, comprising at least one of:

11. 11. A method for manufacturing a flat glass element (1) having a structured wall or a flat glass element (1) according to any one of claims 1 to 10, wherein the glass element (1) has a thermal expansion coefficient of 10x10 －６ K －１ and two opposing surfaces (2), - providing said glass element (1), - directing a laser beam (100) of an ultrashort pulse laser onto one of the faces (2) of the glass element (1), focusing the laser beam (100) to a long focus within the glass element (1) by means of a focusing optics (102), and generating, by the radiation energy of the laser beam (100), a multitude of filamentous channels (16) within the volume of the glass element (1), the channels (16) extending transversely to the face of the glass element (1) and the channels (16) being spaced apart from one another; - exposing the glass element (1) to an etching medium (200), which removes glass from the glass element (1) at an ablation rate, and which widens the channels (16) with the etching medium (200), thereby forming a recess (10) with a structured recess wall (10), which recess wall (10) has a structure comprising a multitude of mutually adjoining rounded dome-shaped depressions (12) extending around the periphery of the recess (10) and bordering the two opposing faces (2), said structure forming the roughness of the recess wall (10); - by setting the laser parameters, the structure or the roughness of the recessed walls (10) is adjusted in a targeted manner, so that the average roughness value (Ra) of the recessed walls (10) is less than 3 μm, preferably less than 1 μm and preferably at least 50 nm; The channels (16) are spaced apart (18) from one another, the spacing (18) being less than 50 μm and greater than 5 μm; The ablation rate is less than 5 μm per hour; Selecting a pulse duration of less than 10 ps; method.

12. 12. The method of claim 11, wherein the channels (16) are spaced apart from one another by a distance (18), the distance (18) being smaller than 20 μm, preferably smaller than 15 μm, preferably smaller than 10 μm and / or larger than 1 μm, preferably larger than 2 μm, preferably larger than 3 μm.

13. A method as described in claim 11 or 12, wherein a laser pulse from the ultrashort pulse laser is divided into a plurality of single pulses, the plurality being less than 10, preferably less than 8, preferably less than 7 and / or greater than 1, preferably greater than 2, preferably greater than 3.

14. The method of claim 11, wherein a pulse duration of less than 5 ps, preferably less than 1 ps, is selected.

15. 15. The method according to any one of claims 11 to 14, wherein recesses (10) and / or outer walls (11) are produced with different roughnesses, the difference in roughness of the recesses (10) and / or outer walls (11) being at least greater than 0.5 μm, preferably greater than 1 μm, or particularly preferably greater than 2 μm.

16. 11. Use of a glass element according to any one of claims 1 to 10 in at least one of the fields of camera imaging, in particular 3D camera imaging, pressure sensor technology, packaging of electro-optical components, biotechnology, diagnostic technology, medical technology.

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