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 flat glass element having a thermal expansion coefficient of 10×10 -6 K -1 below The present invention relates to a sheet glass element having a vitreous material, two opposing faces, and a recess extending through the glass of the glass element and having a structured recess wall. The present invention further relates to a method for manufacturing a sheet glass element having a structured wall, wherein the structure of the recess wall is adjusted in a targeted manner by setting laser parameters.

[0002] Precise structuring of glass is of great interest in many application fields. Among these, glass substrates are used in camera imaging, especially 3D camera imaging, electro-optics, e.g., L(E)D in microfluidics, optical diagnostics, and sensor technology, e.g., pressure sensor technology and diagnostic technology. Such application fields relate, for example, to optical sensors, camera sensors, pressure sensors, light-emitting diodes, and laser diodes. In this case, glass substrates are often used as components in the form of thin wafers or glass films. To enable such glass substrates to be used in increasingly miniaturized industrial applications and components, precision in the range of several micrometers is required. Here, processing of glass substrates refers to the introduction of holes, cavities, and openings of any shape into or through the glass substrate, as well as the structuring of the substrate surface. Therefore, structures in the range of several micrometers must be introduced into the substrate.

[0003] Additionally, to enable glass substrates to be used in a wide range of applications, it is desirable that processing not leave damage, residue, or stress on the edge regions or volume of the substrate, and that the method for manufacturing such substrates should enable as efficient a manufacturing process as possible.

[0004] Various methods can be used to create structures in glass substrates, for example holes or openings.

[0005] Established methods include ultrasonic vibration lapping, as well as water blasting and sand blasting using appropriate masks. However, these methods are limited to small structures in terms of scaling: typically around 400 μm for ultrasonic vibration lapping and at least 100 μm for sand blasting. Water blasting and sand blasting induce stresses in the glass due to mechanical ablation, which leads to concomitant spalling in the edge area of ​​the hole. Essentially, neither of these methods can be used to structure thin glass. Since these methods operate in the range of several hundred μm, this not only affects the dimensions of the resulting holes, cavities, and openings, but also, above all, the resulting surface of the substrate. Therefore, the aforementioned methods are not suitable for forming microstructures in substrates.

[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 (e.g., 1064 nm), green (532 nm), and ultraviolet (365 nm) wavelengths, as well as ultrashort wavelengths (e.g., 193 nm and 248 nm), allow for the introduction of smaller structures into glass substrates than are possible with the mechanical methods described above. However, due to the low thermal conductivity and fragility of glass, laser processing can also result in high thermal loads in the glass when creating very fine structures, which can lead to critical stresses and microcracks and distortions around the edge of holes. Furthermore, even with a fine laser beam with a diameter of only a few micrometers, creating large-area structures on the substrate surface requires a very large effort. This makes this method only suitable to a limited extent for industrial production of substrates requiring structuring, especially in the aperture area.

[0007] This is especially true for components and substrates that must be suitable for specific applications. For example, glass substrates for microfluidic cells require particularly smooth surfaces within the channels to minimize fluid resistance at the channel walls. Another application area is electro-optical converters, which use customized glass spacers. These opto-electrical converters allow for the adjustment of specific spacings between various active and passive components or serve to enclose and protect particularly sensitive components, such as electromagnetic transducers / emitters / receivers. To optimally fix or even insulate these sensitive components within the openings of the substrate or spacer, a special structuring of the substrate's opening surface is required. Furthermore, specific optical properties of the substrate, for example, in terms of improved optical conductivity, are often required, which can be achieved by a specific structure of the opening surface that refracts light in a specific way.

[0008] However, known methods are unable to produce such structures. As mentioned above, polishing methods are unable to produce microstructured openings, and therefore are unable to precisely adjust the opening surface of the microstructure in the substrate. 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 the substrate surface extending parallel to the laser beam cannot be processed in the same way. Furthermore, reprocessing the opening surface of each opening in the substrate with the laser beam is uneconomical, as it is very time-consuming and costly. Furthermore, the processing of such openings can only be performed within a limited range due to the laser's angle of incidence.

[0009] The present invention is therefore based on the problem of providing a substrate with a specially structured open surface and a method for producing the same. This problem is solved by the subject matter of the independent claims. Advantageous developments are given in the respective dependent claims.

[0010] Therefore, the present invention is based on a thermal expansion coefficient of 10×10 -6 K -1 belowThe present invention relates to a flat glass element having a vitreous material and two opposing surfaces. The glass element further has at least one recess connecting the two surfaces, opening into these surfaces, and penetrating the glass of the glass element. The recess has a recess depth, which is transverse, preferably perpendicular, to at least one of the surfaces of the glass element and corresponds to the thickness of the glass element. The recess has a recess wall that extends around the recess and borders 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 a surface roughness of 5 μm. below , preferably 3 μm below , preferably 1 μm below , particularly preferably 500 nm below According to a further embodiment, however, the walls have a minimal roughness, in particular the average roughness of the recessed walls is at least 50 nm.

[0011] Due to the particularly smooth recessed walls of the glass element, the glass element is particularly suitable for use in the field of microfluidics. The recess can be configured as a long fluid channel through which the fluid can flow almost unimpeded. In this case, the two faces can also run parallel to each other. This has the advantage that several glass elements can be arranged parallel to each other in a plane, without any misalignment. In this way, several glass elements can be arranged one on top of the other in a sandwich structure. This is particularly necessary in microfluidic cells, where fluids are guided into a channel by means of a stack of typically three or more components, with components arranged above / below the channel on two faces forming the boundary of the channel.

[0012] In one particular embodiment, the average roughness value (Ra) of the recessed wall and / or the outer wall is at least 50 nm, advantageously at least 0.2 μm Exceeding , preferably 0.4 μm Exceeding , preferably 0.5 μm ExceedingSuch low roughness not only allows applications in microfluidics but also allows the achievement of special optical properties. This is particularly true for roughnesses in the range of 5 μm to 0.2 μm. For example, with an Ra of 5 μm, the glass element has a concave wall surface that is less glossy than with an Ra of 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 ridge surrounding the depression. By dome-shaped, in the sense of the present invention, it is understood that the depression wall has a curvature that appears concave, in particular in the direction of the glass of the glass element, and that the curvature can protrude into the glass element in the form of a dome, without being limited to a specific cross-section. Advantageously, the roughness of the depression wall is determined by the depth of the dome-shaped depression. This means that the depth of the depression determines the average roughness value within the sense of the present invention. 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 is greater than 0.2 μm, preferably greater than 0.4 μm, and preferably greater than 0.5 μm. The dome-shaped depressions inhibit crack formation and crack propagation because the non-flat portions, especially the curved portions, hinder crack growth.

[0014] The dome-shaped depressions can all have a substantially uniform depth, or they can have different depths, for example. It is also possible for the dome-shaped depressions to be arranged with a height offset. This means that some depressions are arranged with a height offset relative to other depressions, particularly from the imaginary central plane of the recessed wall in a direction perpendicular to this plane. Here, the depressions can also be offset regionally relative to the imaginary central plane of the recessed wall, where regionally means that several depressions are offset by the same amount. 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 areas can also be formed in the form of dots or stripes, for example, stripes, where the stripes can be oriented transversely or parallel to the surface of the glass element. In this way, ripples can be formed on the recessed wall, and the ripples can be oriented particularly transversely and / or parallel to the surface of the glass element. Such ripples can improve the retention of components placed in the recesses of, for example, the glass element or glass substrate.

[0015] In an advantageous embodiment, the cross-sectional or transverse dimension or diameter of the dome-shaped depression is less than 20 μm, preferably less than 15 μm, preferably less than 10 μm. However, some depressions may have a diameter or cross-section of less than 60 μm, preferably less than 50 μm, preferably less than 40 μm. By skillfully selecting the size and dimensions of the depressions, for example, the friction and resistance of an object or a fluid against the depression wall can be determined, thereby improving the fixation of the object or improving the flow of a fluid through the depression. It is conceivable that the dome-shaped depressions have at least one of the following shapes: circular, elliptical, worm-shaped, or elongated, e.g., rounded shapes formed by multiple integrated depressions, or polygonal, e.g., hexagonal. Furthermore, the ridges may be formed as polygonal boundaries between the depressions. In this case, the average number of corners of the depression boundaries may be advantageously less than 8, preferably less than 7, in particular 6. This characteristic arises when the area occupied by the majority of the dome-shaped depressions is convex in a mathematical sense. By setting an appropriate shape of the recess, the recessed wall or glass element can be / is better adapted to a particular application.

[0016] It is also advantageous if the glass element has an outer wall that extends around the periphery of the glass element and connects the two faces, and that has a structure with a number of adjacent rounded, dome-shaped recesses. In this case, the outer wall can have features corresponding to the previously described embodiment of the recessed wall. In this way, the glass element itself can also be positioned in another component so that it does not slip, for example, due to a particularly rough outer wall.

[0017] It is further possible for the recessed wall and / or the outer wall to form rounded edges. This is understood within the meaning of the present invention as meaning that one or more surfaces of the recessed wall and / or the outer wall are rough or structured over the entire surface. In other words, one or more surfaces of the recessed wall and / or the outer wall have a continuous, uninterrupted structure of dome-shaped depressions and / or ridges arranged between the depressions. As a result, the recessed wall and / or the outer wall are effectively protected from crack growth or the growth of cracks is minimized, and the glass element is therefore better protected against microcracks.

[0018] In the context of the present invention, this is understood to mean that one or more surfaces of the recessed wall and / or outer wall are rough or structured over the entire surface. In other words, 80%, 90%, particularly preferably 95% or even 98% of the surface of one or more of the recessed wall and / or outer wall have a continuous, uninterrupted structure of dome-shaped depressions and / or ridges arranged between the depressions. This allows the method according to the present invention to produce a large 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 support, particularly a peripheral support in the form of a frame, by one or more bridge-like connections. When the part is in use, the bridge-like connection is separated from its support, for example, by a classical breaking process, optionally combined with the introduction of a predetermined break, for example, by filamentation along the target part contour over the entire bridge.

[0019] In addition, the transmittance of visible light in the wavelength range of 300 nm to 1000 nm through the structured outer wall and / or recessed wall and the glass element, preferably also through a second wall arranged opposite the recessed wall and / or outer wall, is 80%. Exceeding , preferably 85% Exceeding , preferably 90% ExceedingIt is also conceivable that the light direction is oriented perpendicular to the recessed wall and / or the outer wall and parallel to at least one face of the glass element. In this case, the light path may be arranged to cross at least one, preferably two, walls or faces, at least one of which, and optionally both, has a dome-shaped depression. Such high transmittance provides the glass element or recessed wall with particularly high optical quality. This makes the glass element particularly suitable for optical applications, and it can be used, for example, as an optical component or light guide.

[0020] In one embodiment, 1 μm exceed The concave wall and / or outer wall have an average roughness value of 1 μm below It may further be envisioned that the recessed wall and / or outer wall may have a lower reflectivity than a recessed wall having an average roughness value. In this case, the recessed wall and / or outer wall may exhibit a decrease in reflectivity as the average roughness value increases. For example, a recessed wall and / or outer wall having an average roughness value of 0.5 μm may have approximately twice the reflectivity of a recessed wall and / or outer wall having an average roughness value of 1.4 μm. Therefore, by selecting a particular roughness value for the recessed wall and / or outer wall, the glass element may be particularly well suited for certain optical applications. Therefore, a recessed wall with high roughness can be easily distinguished from a recessed wall with low roughness by an image processing device due to its scattering behavior with respect to visible light, and therefore can be used, for example, for aligning the glass element as a whole.

[0021] It may be assumed that the roughness of the recess wall and / or the outer wall is anisotropically formed, whereby the anisotropy can be expressed as a parameter A. In this case, A is the square of the quotient, which is formed from the average value of the average roughness values ​​(Ra) of three 30 μm-wide measurement strips oriented parallel to a side surface of the glass element and the average value of the average roughness values ​​(Ra) of three 30 μm-wide measurement strips 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 values ​​of three measurement strips extending along the edge surface of the recess and the average value of three measurement strips extending perpendicularly thereto. The latter perpendicularly extending measurement strips thus extend from one side surface to the opposite side surface. In particular, this anisotropy may be less than or equal to 1, preferably less than or equal to 0.8, and preferably less than or equal to 0.6. A side surface in the sense of the present invention can be understood here as at least one of the two opposite sides of the glass element. The anisotropy can be formed by the offset of ripples or dome-shaped depressions relative to one another. In this case, the ripples or anisotropically formed roughness allow other components, such as electrical components, to be placed in the recesses, and these components are protected from displacement by increasing friction against the recess walls when moving along them, especially in a direction perpendicular to the surface of the glass element. In this way, the components placed in the recesses remain firmly fixed in the recesses, for example, even in the event of vibrations.

[0022] It is also envisioned that the roughness of the recess wall and / or the outer wall is anisotropically formed, the anisotropy being represented by a parameter A, where A is the square of the quotient formed by 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 and the average value of the average roughness values ​​(Ra) of three 30 μm-wide measurement bands oriented perpendicular to this side of the glass element, and the anisotropy is 1 or more, preferably 2 or more, and preferably 3 or more. In this embodiment, the ripples may be oriented perpendicular to the glass surface, so that the anisotropically formed roughness can protect other components in the recess, such as electrical components, from slippage when they move along the recess wall, especially in a direction parallel to the surface of the glass element, by increasing friction with the recess wall. On the other hand, the ripples oriented perpendicular to the glass surface increase the mobility of the components, allowing them to be more easily displaced. This is advantageous when the component is subjected to repeated mechanical loads, as is the case for example with pressure sensors, and the mobility of the component within the glass element can protect both the component and the glass element from increased wear.

[0023] Overall, therefore, in one embodiment, the anisotropy (A) - greater than 1, - advantageously greater than 1.5, - or even greater than 4, or - Less than 1 This can be advantageous in some cases.

[0024] Furthermore, it is possible for the anisotropy (A) to be greater than 8, 9 or 10. In such embodiments, ripples can be particularly pronounced.

[0025] In a further advantageous embodiment, the roughness of the recessed wall and / or the outer wall is directionally dependent, the roughness appearing differently in at least certain sections, the sections being - oriented transversely to the recess depth or to at least one face, or - oriented parallel to the recess depth or at least one face, The difference in the average roughness values ​​of the sections is then less than 4 μm, preferably less than 2 μm, and more preferably less than 1 μm. However, the direction-dependent roughness can also be formed, for example, by dome-shaped depressions offset relative to the imaginary center plane of the recessed wall. The direction-dependent roughness can, for example, allow targeted placement of air chambers between the recessed wall and the component to improve thermal or electrical insulation. Furthermore, a well-chosen anisotropic structure, in particular ripples, can also allow the fluid to penetrate channel-shaped recesses better, for example, when the ripples are oriented along the fluid flow direction or perpendicular to the flow direction to achieve a particularly slow flow.

[0026] In an 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, thicknesses greater than 300 μm or less than 10 μm, preferably less than 4 mm, preferably less than 2 mm, preferably less than 1 mm are also possible. In particular, such thin glass can be structured very finely and without risk of breakage by the methods described herein. Furthermore, due to their small thickness, the glass element can be made flexible and therefore bendable. Since other bonding forces often play a significant role due to their small thickness, the glass element can also be made 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, it is also possible to use glass elements in the thickness range of 300 μm to 3 mm, in special cases even up to 6 mm, which do not deform or only deform slightly under the action of forces.

[0028] In a further embodiment, the glass element has lateral dimensions greater than 50 mm, preferably greater than 100 mm, preferably greater than 200 mm and / or smaller than 500 mm, preferably smaller than 400 mm, preferably smaller than 300 mm. Small glass elements, each having, for example, one or more recesses, can then be cut out from such a glass element. According to a further embodiment, such small glass elements or glass elements can have lateral dimensions of at most 5 mm, advantageously at most 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 comprises the following components: an SiO content of at least 30% by weight, advantageously at least 50% by weight, particularly preferably at least 80% by weight, - TiO2 content up to 10% by weight It includes at least one of the following:

[0030] Ideally, the glass of the glass element is formed as a borosilicate glass, which has particularly high thermal stability, transparency, and chemical and mechanical stability and is therefore highly suitable for a wide range of applications, for example, in optical and electronic applications.

[0031] The problem is also solved by a sheet glass element having a structured wall or a method for manufacturing a sheet glass element according to at least one of the previously described embodiments. The glass element has a thermal expansion coefficient of 10×10 -6 K -1 belowa glassy material and two opposing surfaces, - Provide glass elements, - directing a laser beam of an ultrashort pulse laser onto one of the faces of the glass element, and focusing the laser beam by means of focusing optics to a long focus within the glass element, in which case the irradiation energy of the laser beam generates a multitude of filamentous channels within the volume of the glass element, the depth of the channels extending transversely to the face of the glass element and the channels being spaced apart from one another; - exposing the glass element to an etching medium, which removes glass from the glass element at an ablation rate, and in so doing widening the channel with the etching medium to form a recess with a structured recess wall, the recess wall extending around the periphery of the recess, bordering two opposing faces, and having a structure with a multitude of bordering rounded dome-shaped depressions, which structure forms the roughness of the recess wall, where the recess wall can also be understood as the inner edge of the recess.

[0032] In preferred embodiments, the filamentary channels are arranged along a closed contour, which can in principle be any two-dimensional shape, in preferred embodiments the contour follows a regular two-dimensional geometric element, such as a circle, ellipse, rectangle, square or polygon, so that after completion of the structured glass substrate, the recesses according to the invention can serve as containers for, for example, electronic components.

[0033] By setting the laser parameters, it is advantageous to adjust the structure or roughness of the recessed walls in a targeted manner, so that the average roughness value (Ra) of the recessed walls is 5 μm. below , preferably 3 μm below , preferably 1 μm below However, the average roughness value is advantageously at least 50 nm.

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

[0035] It is envisaged that the method can also be used to produce glass elements according to the aforementioned embodiments, thereby achieving the aforementioned advantages. In this case, the method allows for the simultaneous production of multiple recesses in multiple glass elements, making the method particularly suitable for industrial production processes. 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 preferably multiple, particularly preferably multiple, damages, in particular in the form of filamentary channels, are created in the glass element, ideally forming holes in the glass element through the damage / channels. The holes are preferably widened during a subsequent etching step, to the extent that the channels merge and thereby allow individual portions of the glass element to be detached from the glass element, thus creating the recesses.

[0036] For this purpose, it is advantageous to generate a plurality of damages / channels next to one another, so that a series of recesses forms a structure in the form of larger, ideally generated recesses, with the damages / channels extending transversely to at least one, ideally both, faces of the glass element, in which case the channels penetrate vertically through the glass element from one face, in particular from this face to the other, oppositely arranged face, and penetrate both faces.

[0037] The damage / channel is generated in the glass element by at least one laser beam of an ultrashort pulse laser. The generation of the recess by laser is advantageously based on the following steps: - a laser beam from an ultrashort pulse laser is directed at one of the faces of the glass element, which can be focused to a long focus within the glass element by means of focusing optics, and the emission wavelength can be selected so that the glass element is substantially transparent, i.e., the transmittance is greater than 0.9, preferably greater than 0.95, particularly preferably greater than 0.98.

[0038] - the glass element is irradiated with one or more pulses or groups of pulses (so-called burst pulses) by an ultrashort pulse laser, whereby the interaction of the electromagnetic field of the high-power laser pulse with the glass element advantageously initiates a nonlinear absorption of the laser energy, which advantageously results in a filamentary damage (in particular in the form of a substantially cylindrical channel) in the material of the glass element at the long focus, which filamentary damage then expands into the channel.

[0039] In this way, a number of channels are generated, the channels, in particular their arrangement on or in the glass element, being selected so that a number of channels arranged next to each other form the contour of the recess to be generated, the channels being able to be spaced apart from each other.

[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 has a wavelength of, 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 suitable beam-shaping optics, such as a Galilean telescope. The laser source typically operates at a repetition rate of 1 kHz to 1000 kHz, preferably 2 kHz to 100 kHz, and particularly preferably 3 kHz to 200 kHz. In this case, the repetition rate and / or the scanning speed can be selected so that the desired distance between adjacent lesions / channels is achieved.

[0041] As beam sources, other variants of Nd:YAG lasers, such as those with wavelengths of 532 nm or 355 nm produced by frequency doubling (SHG) or frequency tripling (THG), or even Yb:YAG lasers (emission wavelength 1030 nm) can be suitably used.

[0042] It is also conceivable to divide the laser pulse into a plurality of single pulses, the plurality being less than 10, preferably less than 8, preferably less than 7 and / or more than 1, preferably more than 2, preferably more than 3. These single pulses can be grouped into pulse packets, so-called bursts, which are in particular emitted in successive laser pulses. Advantageously, these single pulses are directed at the same point or location on the glass surface, so that the damage caused by the successive single pulses is spread even further, preferably resulting in a channel penetrating the entire thickness or volume of the glass element.

[0043] Advantageously, by skillfully selecting the number of single pulses in a pulse packet, the generated recess / channel wall can be influenced, particularly the structure of the recess / channel wall can be tailored. Because the total power of the laser pulse is divided into multiple single pulses in a pulse packet or burst, each pulse has a lower energy than a single laser pulse. Therefore, the energy of each single pulse decreases with the number of single pulses. However, it is possible for the pulse energy of the single pulses to be flexibly adjusted, in particular, for the pulse energy to remain substantially constant, increase, or decrease, with the first single pulse of a burst or pulse packet preferably having either the lowest or highest energy of the single pulses. Furthermore, when an ultrashort-pulse laser is operated in burst mode, the repetition frequency can be the repetition frequency of the burst emission. Furthermore, because the single pulses strike the surface or the damage of the glass element at different times, each single pulse changes the previously generated state of the recess / channel wall. In this way, by selecting the number of single pulses in one burst, the recess / channel walls can be structured and modified in a targeted manner.

[0044] Here, a typical power of the laser source is particularly advantageously in the range of 20-300 watts. To achieve the lesion / channel, according to an advantageous development of the invention, pulse energies of pulses and / or pulse packets greater than 400 microjoules are used, and even more advantageously, total energies greater than 500 microjoules are used. The preferred pulse duration of the laser pulses is in the range of less than 100 picoseconds, preferably less than 20 picoseconds.

[0045] However, it may be envisaged to select a pulse duration of less than 15 ps, preferably less than 10 ps, ​​preferably less than 5 ps. Advantageously, a pulse duration of even 1 ps is used to produce smooth recess / channel walls with particularly low roughness or low average roughness values. Here, the roughness can increase with increasing pulse duration. One possible reason for this is the thermal behavior of the glass. With longer pulse durations, the glass is exposed to the energy of the laser longer, and thus to the heat of the generated laser beam, which can damage particularly thermally instable glasses, for example, by expansion. Therefore, by accurately selecting the pulse duration and, ideally, the roughness of the recess / channel walls, the glass of the glass element can be damaged in a specific manner. This can also mean that glasses with a low thermal expansion coefficient are less damaged than glasses with a high thermal expansion coefficient. Here, the pulse duration is essentially independent of whether the laser operates in single-pulse mode or burst mode. The pulses in the burst usually have a pulse length similar to that of the pulses in single-pulse mode. Here, the burst frequency can be in the range of 15 MHz to 90 MHz, preferably in the range of 20 MHz to 85 MHz, for example, 50 MHz.

[0046] It is also advantageous if the channels are spaced apart from one another by a distance of less than 20 μm, preferably less than 15 μm, preferably less than 10 μm and / or more than 1 μm, preferably more than 2 μm, preferably more than 3 μm, but the spacing between channels can also be more than 5 μm and / or less than 100 μm, preferably less than 50 μm, preferably less than 15 μm.

[0047] Regardless of the channel diameter, the spacing between adjacent channels can also be referred to as the pitch, i.e., the spacing between laser pulses emitted simultaneously or, in particular, successively at offset intervals from one another. Here, this spacing can be measured from the center of the channel to the center, or from the center of one pulse to the center of the adjacent pulse. The roughness can be influenced by the choice of channel spacing, in that the section between the channels has dimensions corresponding to the thickness of the glass element and the spacing between the channels, and does not need to be intentionally processed with a laser, but is only subjected to a subsequent etching process.

[0048] Thus, two different regions can be generated: one in which the surface is structured by the laser and preferably by the etching medium, and another in which the surface is structured only by the etching medium, to which the glass element is exposed after the channel is generated. In this way, a directionally dependent or anisotropic roughness can be generated, particularly of the recessed walls. In this case, the region between the channels can preferably have a different roughness than the region of the channels, with the longitudinal extent of both regions preferably extending parallel to the laser beam or transversely, in particular perpendicularly, to at least one surface of the glass element, thereby ideally achieving an anisotropy greater than 1.

[0049] In a further, preferably final, step, the glass element, including the channels formed in the glass element, is exposed to an etching medium, thereby removing the glass of the glass element at a definable ablation rate, and the channels are expanded by the etching medium, particularly the ablation that results from it. In this way, a recess with a structured recessed wall can be formed, preferably also multiple recesses. In this case, a dome-shaped depression in the recessed wall and / or outer wall can be typically generated by ablation. It is advantageous if the etching medium is filled into a container, such as a tank, pot, or vessel, and then one or more glass elements are at least partially held or immersed in this container or etching medium.

[0050] The etching medium may be gaseous, but is preferably an etching liquid. Thus, according to one embodiment, the etching is performed wet-chemically. This is advantageous for removing glass components from the channel inner surface during etching. If the channel walls are configured to be particularly non-planar or planar, for example, by selecting appropriate laser parameters, such as burst, pitch, and / or pulse duration, depressions can be added to the recess / channel walls by etching or wet-chemical etching ablation or material ablation. This allows for the creation or production of recess walls with particularly advantageous dome-shaped depressions, with high or low roughness, as required.

[0051] It is contemplated to use acidic or even alkaline solutions as etching solutions. Suitable acidic etching media include HF, HCl, H2SO4, ammonium bifluoride, 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 a low alkali metal content, because basic etching solutions are less likely to quickly become supersaturated in such glasses and therefore retain their etching ability much longer than in strongly alkaline glasses. Therefore, it is ideal to select the etching medium used depending on the glass of the glass element to be etched. Therefore, depending on the glass composition, acidic etching media can be selected to achieve high ablation rates in silicate glasses, or basic, especially alkaline, etching media can be selected to achieve low ablation rates.

[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., in particular up to 100° C. This temperature allows sufficient mobility of the glass ions or components of the glass element to be dissolved from the glass matrix.

[0053] Another factor is time. For example, if the glass element is exposed to the etching medium for several hours, in particular for more than 30 hours, a high overall ablation rate can be achieved. On the other hand, it is possible to limit the ablation rate by exposing the glass element to the etching medium for less than 30 hours, for example only 10 hours. In the best case, the ablation rate is selected so that the dome-shaped depression forms a shape with the largest volume at the smallest mathematical perimeter or cross section, in particular a circular, or even approximately hexagonal or polygonal shape. In this way, a uniform roughness of the recessed wall can be achieved.

[0054] The invention will now be described in more detail with reference to the accompanying drawings, in which like reference numerals indicate the same or corresponding elements, and in which: [Brief explanation of the drawings]

[0055] [Figure 1] 1 is a schematic diagram illustrating the creation of damage in a glass element by a laser. [Figure 2] FIG. 1 is a schematic diagram showing a glass element having multiple damages. [Figure 3] 1 is a schematic diagram showing the etching process of a glass element. [Figure 4] 1 is a schematic diagram showing the glass element after the etching step and separation of the portions to create recesses. [Figure 5] 1 is an electron microscope photograph of a concave wall of a glass element. [Figure 6] FIG. 10 shows the measurement results of the roughness of the recessed wall versus the pulse duration. [Figure 7] FIG. 10 shows the measurement results of the roughness of the recessed wall with respect to the burst. [Figure 8] FIG. 10 is a diagram showing measurement results of the roughness of the recessed 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] FIG. 1 shows the measurement results of a highly isotropic concave wall surface parallel to the laser with a pulse duration of 10 ps. [Figure 11] FIG. 1 shows the measurement results of a highly isotropic concave wall surface perpendicular to the laser with a pulse duration of 10 ps. [Figure 12] FIG. 1 shows the measurement results of a concave wall surface that does not exhibit obvious isotropy with a pulse duration of 10 ps. [Figure 13] FIG. 1 is a schematic diagram showing measurement of the transmittance of a recess wall. [Figure 14] FIG. 10 is a diagram showing the results of measuring the reflectance of a recessed wall.

[0056] FIG. 1 shows a schematic representation of a glass element 1. The glass element 1 has two faces 2, which are arranged opposite each other so that the volume of the glass element is located between them, and a thickness D that defines the distance between the two faces 2. The faces may be arranged parallel to each other. The glass element 1 further extends in a longitudinal direction L and a transverse direction Q. Preferably, the glass element 1 also has at least one outer face 4, which ideally completely surrounds the glass element 1 and whose height corresponds to the thickness D of the glass element 1. In this case, the thickness D of the glass element 1 and the height of the side faces 4 ideally extend in the longitudinal direction L, while the faces of the glass element can extend in the transverse direction.

[0057] In a first process step, a laser 101, preferably an ultrashort pulse laser 101, is used to create damage, in particular in the form of channels 16 or channel-shaped damage 16, in the volume of the glass element 1. For this purpose, a laser beam 100 is focused onto the surface 2 of the glass element by means of a focusing optics 102, for example a lens with uncorrected spherical aberration or a lens system in which the spherical aberration increases due to the cumulative effect of the individual elements. By focusing the laser beam 100, in particular by a long focusing, on a region within the volume of the glass element 1, the energy of the laser beam 100 thus emitted creates filament-like damage that in particular further extends into channels 16, for example by using burst mode, in which the damage or channels 16 are created by a plurality of single pulses in the form of pulse packets.

[0058] To optimally structure the surface of the recess 10 to be generated in a subsequent process step, it may be advantageous to precisely set certain laser parameters so that the surface is, as it were, pre-processed during the generation of the damage and / or channels. For this purpose, at least one of the following parameters can be precisely set: the pulse duration of the laser beam 100, which is preferably 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 laser frequency. While not limiting the present embodiment, the pulse packet frequency can be, for example, 12 ns to 48 ns, preferably about 20 ns, the pulse energy can be at least 200 microjoules, and the burst energy can be, correspondingly, at least 400 microjoules. By appropriately selecting specific values ​​for these parameters, the roughness of the recess wall 11 of the generated recess 10 can be precisely set as early as possible.

[0059] Advantageously, as shown in Fig. 2, in a further step a plurality of channels 16 are generated, which are ideally arranged next to each other, so that the multitude of channels 16 result in holes, and these holes or the multitude of channels 16 form the contour of the structure 17. In the best case, the structure 17 thus generated corresponds to the shape of the recess 10 to be generated, i.e. the spacing 18 and number of channels 16 are selected so as to form the contour of the recess to be generated. 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] 3 shows a further step. After the laser 101 has produced a multitude of channels 16 in the glass element 1, the glass element 1, preferably structured by the channels, is placed in an etching medium 200. For this purpose, the glass element is preferably removably arranged on a holder 50, whereby the glass element 1 can simply rest or be fixed to the holder 50. Here, the glass element 1 is held, in particular immersed, by the holder 50 in the etching medium 200, preferably an etching solution, which is preferably arranged in a container 202. Ideally, the container 202 for this purpose comprises a material that is substantially resistant to the etching medium 200. This means that the composition of the etching medium 200 is ideally not changed by contact with the container 202, either because the material of the container 202 is substantially durable and therefore the etching medium 200 attacks or erodes the container material only to a small extent, or because the ions and atoms of the container 202 material remain substantially within the volume of the container 202 upon contact with the etching medium 200. However, it is also possible that the composition of the etching medium 200 is influenced by contact with the container, in particular that container components released from the container 202 can change the etching properties of the etching medium 200 and thereby change the ablation rate of the ablation 70 of the glass element in the desired direction. However, it is also possible to change the ablation rate, for example, by physically and / or mechanically induced movement of the etching medium 200, in particular by stirring, for example, by a magnetic stirrer, or by local temperature changes. Advantageously, an optimal ablation rate is achieved by subjecting the etching medium 200 to a temperature between 40°C and 150°C.

[0061] Preferably, an acidic or alkaline solution is used as etching medium 200, in particular an alkaline solution, such as KOH. Ideally, a basic etching medium 200 with a pH value >12 is used, for example a KOH solution with a concentration of >4 mol / l, preferably >5 mol / l, particularly preferably >6 mol / l, but <30 mol / l. Without being limited to this embodiment, etching is advantageously carried out at a temperature of the etching medium of >70°C, preferably >80°C, particularly preferably >90°C, in particular about 100°C, or at a temperature below 160°C.

[0062] The ablation 70 or ablation rate can be adjusted, for example, by the exposure time of the glass element 1 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. An ablation rate of less than 5 μm per hour is optimal to achieve the desired roughness of the channel walls or channels 16 pre-structured by the laser 100, or the resulting recesses 10 or recess walls 11. 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, reaching 34 μm after 16 hours of etching, 63 μm after 30 hours, and 97 μm after 48 hours.

[0063] Ideally, the ablation 70 and etching times are selected so that material between adjacent channels is removed to the extent that the channels merge, particularly by merging channels 16, to form a connected opening, as shown, for example, schematically in FIG. 4. Without being limited to the example shown in FIG. 4, the connected opening can have any other shape and / or contour. What is important, however, is that the channels 16 merge to form a single large opening in the glass element 1, exposing an inner portion 20 of the glass element 1 that was previously surrounded by the channel, which can then be separated or removed. In the process, a recess 10 having a recessed wall 11 is formed.

[0064] Ideally, the recessed wall 11 has a uniform structure with a particularly targeted roughness or average roughness value. However, it may also be advantageous if the recessed wall 11 is / is formed anisotropically, for example by targeted setting of the ablation rate, in particular in such a way that the intermediate regions between the channels are only partially or incompletely removed, so that the recessed wall 11 has such intermediate regions 30 and channel regions 31. By modifying the intermediate regions 30 and channel regions 31, ripples can or may be formed on the recessed wall 11, which advantageously form an anisotropic or directionally dependent roughness of the recessed wall 11.

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

[0066] From these relationships, it is clear that the laser parameters, especially the pitch and the number of single pulses in the burst, or pulse packet, have a significant effect on the roughness of the recessed wall.

[0067] FIG. 5 shows an electron microscope photograph of the channel section 31 of the recessed wall 11. Numerous dome-shaped depressions 12 distributed on the recessed wall 11 are clearly visible. The depressions 12 are arranged adjacent to one another, ideally surrounded by ridges 13, which can, for example, suppress crack growth. As can be seen in the photograph, the depressions 12 form a concave camber. The curvature of the camber extends in the glass volume direction, so that the ridges 13 are higher relative to the center plane than the depression bottoms 14, for example. Here, the depression bottoms 14 essentially form the lowest points of the depression relative to the ridges 13, and advantageously, the ridges 13 form the highest points, i.e., the highest lines. However, the ridges 13 are only very narrow relative to the camber or curvature.

[0068] The depth of the dome-shaped depression may be 10 μm to 0.1 μm, with a depth of 0.2 μm to 2 μm being preferred, since this depth essentially determines the roughness of the depression wall 11, and 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 essentially 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 preferably have cross sections 15 measuring 5 μm to 30 μm, in particular 10 μm to 20 μm. Here, the cross sections 15, or the shape of the depressions 12, can be polygonal. In this case, ridges 13 form the boundaries between the depressions 12, which may also have angular shapes due to the polygonal shape of the depressions 12. Ideally, the depressions 12 are formed during the etching process in such a way that space-saving cross sections 15 are formed, for example, with 5 to 8 corners, preferably exactly 6, because this shape mathematically provides the smallest perimeter while maximizing the volume, i.e., it is closest to a circle. In particular, this allows for a uniform and consistent roughness to be set, and therefore the glass element can be particularly precisely adapted to the intended application.

[0070] Figure 6 shows a graph of the average roughness (Ra) measurements on the recess wall 11 resulting from the combination of the laser-induced damage 16 and subsequent etching to create channels 16. The graph plots the average roughness (Ra) produced by the process described above versus various laser parameters. The average roughness (Ra) is plotted on the vertical axis, and the number of single pulses in the burst or pulse packet on the horizontal axis. The size or diameter of the measurement points represents the pitch, or the spacing between pulses and channels. Furthermore, the right side shows roughness measurements produced with a pulse duration of 1 ps, while the left side shows roughness measurements produced with a pulse duration of 10 ps. The distribution of the average roughness (Ra) clearly shows the correlation between roughness and pulse duration, number of pulses, and pulse spacing.

[0071] As the graph shows, a short pulse duration, e.g., 1 ps, results in a lower average roughness value (Ra) and a smoother surface for the recessed wall 11 than a long pulse duration, e.g., 10 ps. In particular, the graph also shows that a short pulse duration has less influence not only on the pitch but also advantageously on the burst or number of single pulses, compared to a long pulse duration. Thus, for a long pulse duration, e.g., 10 ps, ​​the measured average roughness value (Ra) is particularly high, in the range of approximately 1 μm to 2 μm, especially for a high pitch and a high burst, while for a short pulse duration the average roughness value (Ra) is below 1 μm, regardless of the pitch or burst. below That is, by shortening the pulse duration, a particularly low roughness of the recess wall 11 can be achieved.

[0072] 7 and 8 show the measured average roughness values ​​(Ra) of the recessed wall 11. The average roughness values ​​(Ra) are plotted against the burst, i.e., number of single pulses (plotted on the horizontal axis in FIG. 7; plotted on the vertical axis in FIG. 8), and the pitch, i.e., the spacing between pulse packets (plotted on the vertical axis in FIG. 7; plotted on the horizontal axis in FIG. 8). Both figures show roughness measurements produced with a pulse duration of 10 ps. Here, the line connecting the measurement points indicates the glass ablation removed during the etching process. FIGS. 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 burst. It is clear that the roughness or the measured average roughness values ​​(Ra) are particularly high, e.g., in the range of 3 μm or more, especially when the pitch is high, e.g., 12 μm or more, and when the burst is high, e.g., 7 or more. On the other hand, when the pitch is 6 μm, the roughness or the measured average roughness values ​​(Ra) are particularly high, e.g., in the range of 3 μm or more. ExceedingIn this case, even if the burst is very low, say 1-2, the measured average roughness value (Ra) is relatively high, for example, greater than 1.5 μm. Since the measurement curves run substantially parallel and largely overlap, it can be concluded that ablation only has a small effect on the roughness produced on the recessed wall 11 and / or outer wall 4. In effect, the roughness of the recessed wall 11 and / or outer wall 4 can be adjusted by the selection of the laser parameters, in particular the pulse duration, pitch and burst.

[0073] It is therefore clear that a particularly rough recessed wall 11 and / or outer wall 4 can be produced by a parameter range providing at least one of the following parameters, advantageously a combination of the following parameters: - the pulse duration is long, for example 1 or more, advantageously 3 or more, preferably 5 or more, - The number of single pulses in a pulse packet (burst) is large, e.g., 7 or more; - The pitch is large, for example 10 μm or more.

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

[0075] However, in a further development of the method, in order to separate one or more inner portions 20, at least one small pitch, i.e. the spatial separation between two impingement points of the laser beam 100 on the glass element 1 or on the at least two channels 16, is at most 6 μm, advantageously at most 4.5 μm, and / or the ablation is at most 34 μm. ExceedingIt is envisioned that a low or high pitch in combination with high ablation is particularly advantageous for separating at least one inner portion 20, allowing the channels to expand to the extent that they connect during the etching process, which can be achieved with a sufficiently high degree of ablation.

[0076] 6 to 8 therefore show that the behavior of the glass material, for example the behavior of the thermal expansion coefficient, determines the influence of the selected laser parameters on the roughness of the recessed wall 11. Here, the thermal expansion coefficient is set to 10×10 so that the roughness can be adjusted in the best possible way. -6 K -1 below Glass is purposely chosen. Furthermore, it has a thermal expansion coefficient of 0.1 × 10 -6 K -1 super , advantageously 1 × 10 -6 K -1 Exceeding , particularly preferably 2 × 10 -6 K -1 Exceeding It may be advantageous if the glass has sufficient expansibility to react to the laser energy. Without being limited to the embodiments presented, glasses with an SiO2 content of 30% to 80% by weight and / or a TiO2 content of up to 10% by weight are particularly suitable in terms of processability.

[0077] 9 to 12 show the measured values ​​of the surface of the recessed wall 11 with directionally dependent roughness after ablation of 10 μm in an etching bath in a measurement area of ​​approximately 800 μm width and 750 μm height, where the width of the measurement area is parallel to the surface 2 of the glass element 1 and the measurement height is perpendicular to the surface of the glass element 1 and in particular parallel to the laser beam 100. The scale at the right edge of the photograph makes it possible to read off the roughness or depth (in μm) of the depression 12 relative to the central surface of the recessed wall 11.

[0078] 9 and 10 show recessed walls 11 with anisotropic roughness, in particular, stripe-like roughness extending 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 for short pulse durations of approximately 1 ps, low bursts of 2, and pitches of 10 μm, as shown in FIG. 9. The dome-shaped depressions 12 appear in a barely discernible but clearly distinct pattern, or are arranged opposite one another like a pattern, particularly overlapping in the direction of the laser beam, so that the arrangement of the depressions 12 forms stripes extending perpendicular / transverse to the surface 2 of the glass element. In this case, the depressions 12 exhibit a rounded, or even circular, cross section.

[0079] The situation is different in the case of recessed walls 11, which are formed with 10 ps, ​​a burst of 1, and a pitch of 10 μm, as shown in FIG. 10. As in FIG. 9, the roughness is formed anisotropically, in particular extending parallel to the laser beam or perpendicular / transverse to the surface 2 of the glass element 1. However, the individual depressions 12 are formed in this case in the shape of worms, which advantageously extend parallel to the laser beam 100 and / or perpendicular / transverse to the surface 2 of the glass element 1. Within the meaning of the present invention, a worm-like shape is to be understood in such a way that the ridges 13 around the depressions 12 form a non-uniform height, which in some areas may correspond to the depth of the depression or at least have a height significantly smaller than the height of the majority of the ridges 13 around the depression. When two or more adjacent depressions have such a low height in at least one region of the ridge 13, these depressions 12 appear with a substantially uniform depth in the measurement image, resulting in a worm-like shape due to the individual depressions 12 being arranged in succession. Overall, it can be seen that the recess walls 11 are significantly coarser and therefore less glossy or rougher when a pulse duration of 10 ps is used (FIG. 10; average roughness value 0.50 μm) than when a pulse duration of 1 ps is used (FIG. 9; average roughness value 0.38 μm). Thus, by varying the pulse duration, the average roughness value (Ra) can be adjusted particularly precisely.

[0080] 11 shows a recessed wall 11 with an anisotropically, preferably stripe-shaped, roughness extending transversely 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 advantageously less than or equal to 1. The recessed wall 11 in this case exhibits essentially two stripe-shaped regions, the depressions 12 of each region having a preferably uniform depth, so that these regions differ substantially in terms of their depth. This results in a relatively uniform measurement of the gray value or average roughness value (Ra) of each region.

[0081] 12 shows a recessed wall 11 with an average roughness value of 1.05 μm, produced with a pulse duration of 10 ps, ​​burst 2, and a pitch of 3 μm. In this example, the dome-shaped depressions 12 are substantially uniformly distributed on the recessed wall 11, resulting in little or no anisotropy. The cross sections of the depressions 12, which are advantageously circular or elliptical, also have a relatively similar appearance, resulting in a uniform structure on the recessed wall 11.

[0082] 13 and 14 show schematic diagrams of the setup for a transmittance measurement and the measurement results of a reflectance measurement. The glass element can be transparent, allowing the transmission of visible light, or more broadly, light in the wavelength range from 300 nm to 1000 nm. The structuring of the recessed wall 11 and / or the outer wall 4, produced by the method presented above, has light-shaping properties that are advantageous for suppressing speckle and other interference effects, for example, in laser diodes. For this purpose, the structure of the recess 12 or the wall can be uniform or anisotropic, for example, according to the shapes shown in FIGS. 9 to 12, in order to influence the light passing through. Advantageously, the glass element 1 allows light to penetrate not only the recessed wall 11 and / or the outer wall 4 but also the surface 2 of the glass element, thus enabling the transmission and reception of electromagnetic waves through the glass element 1.

[0083] Particularly advantageously, the walls 11,4 and the volume of the glass element 1, in particular when the roughness (Ra) adjusted by the above-mentioned method is 0.5 μm, are able to transmit more than 90% of light in the wavelength range from 300 nm to 1000 nm. However, if a lower transmittance of the walls 11,4 is desired, the average roughness value (Ra) can be adjusted to, for example, a value of 1.4 μm, so that only, for example, just over 86% of light is transmitted and more light in the wavelength range from 300 nm to 1000 nm is reflected.

[0084] This can be demonstrated in particular by the measurement setup shown diagrammatically in FIG. 13. The transmittance can be measured using an integrating sphere 81 and a light beam 80, for example with a wavelength of 690 nm. In this case, the light beam 80 traverses the outer wall 4 of the glass element 1, which may have a volume of approximately 10 mm and be specially polished, and passes through or penetrates the concave wall 11. The concave wall 11 is positioned at or directly in front of the integrating sphere 81. In this way, the light beam is scattered on the wall 11,4 and can be detected from all angles by the integrating sphere 81. To be able to determine the transmittance of the wall 11,4 independently of the volume of the glass element 1 and / or the further wall, it is also conceivable to subtract the transmittance of the glass element 1 and / or the polished wall volume from the transmittance measurement. To be able to determine the transmittance of the glass element 1 and / or the further wall volume, for example, the transmittance of the glass element 1 can be measured as light passes through the surface 2 of the glass element 1, or the light reflectance of the wall can be determined by reflectance measurement and then subtracted from the overall transmittance measurement result.

[0085] FIG. 14 shows the results of reflectance measurements. Light was directed at the wall 11,4 using an optical waveguide or fiber sensor, and light reflected by the wall 11,4 in the wavelength range of 300 nm to 1000 nm was detected. Advantageously, the measurements reveal that the reflectance can be adjusted by the roughness of the wall 11,4, or a desired reflectance can be set based on the roughness. For example, a rough wall 11, with an average roughness value of, for example, 1.4 μm, exhibited significantly lower reflectance than a less rough or even smooth wall 11,4 with an average roughness value of, for example, 0.5 μm. [Explanation of symbols]

[0086] 1 Plate glass element 2 sides 4. Exterior walls 10 recess 11 Concave Wall 12 Dome-shaped depression 13 Ridge 14 Lower depression 15 cross sections 16 channels / damage 17 Structure 18 corners 20 Inner part 30 Intermediate area 31 Channel Region 50 Holding part 70 Ablation 80 rays 81 Integrating sphere 90 Rough Wall 91 Smooth Wall 100 laser beams 101 Laser / Ultrashort Pulse Laser 102 Focusing optical system 200 Etching medium 202 Container L Vertical Q Horizontal 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, said 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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