METHODS FOR REDUCING PROTRUDING STRUCTURE ON GLASS PARTS AND GLASS PARTS MANUFACTURED USING THIS METHOD

Abstract

The invention relates to a sheet-like glass detail (1) with a first surface (2), a second surface (3) arranged opposite the first surface (2), and at least one hole (10) extending through at least one of the surfaces (2, 3). The hole (10) extends in the longitudinal (L) and transverse (Q) directions, and the longitudinal (L) direction of the hole (10) is horizontal with the surface (2, 3) through which the hole (10) passes. The surface (2, 3) through which the hole (10) passes has at least one of the following technical characteristics: - the surface (2, 3) has at least one height deviation (20) from the surface (2, 3) that at least surrounds the hole (10), - the surface (2, 3) through which the hole (10) passes has an average roughness value (Ra) less than 15 nm, and - the edge (40) between the surface (2, 3) and the hole (10) has no protrusions.

Description

[0001] Method for reducing raised structures on glass elements and glass element produced according to the method

[0002] Description

[0003] The invention relates to a method for producing structured glass elements, as well as to a plate-shaped glass element having a first surface and a second surface arranged opposite the first, as well as at least one recess that penetrates at least one of the surfaces. A wall of the recess has a plurality of dome-shaped depressions. The surface penetrated by the recess has a mean roughness (Ra) of less than 15 nm, or a defined height deviation from the surface, which has a depth above -0.5 gm or a height (H2) below 0.5 gm.

[0004] The precise structuring of glass is of great interest in many application areas. Glass substrates are used in areas such as camera imaging, particularly 3D camera imaging; electro-optics such as LEDs in microfluidics; optical diagnostics; sensors, such as pressure sensors; and diagnostic technology. Such application areas include light sensors, camera sensors, pressure sensors, light-emitting diodes, and laser diodes. Here, glass substrates are usually used as components in the form of thin wafers or glass membranes. To use such glass substrates in ever-smaller technical applications and components, accuracies in the range of a few micrometers are required. The processing of glass substrates involves the creation of holes, cavities, and channels of any shape in or through the glass substrates, as well as the structuring of substrate surfaces.Accordingly, structures in the range of a few micrometers must not only be introduced into the substrates, but also onto the surfaces of the substrates.

[0005] To ensure the glass substrates can be used in a wide range of applications, the processing should also be free of damage, residues (e.g., separated, ablated, or detached material), or stresses in the edge area or volume of the substrate. Furthermore, the process for producing these substrates should allow for the most efficient manufacturing process possible.

[0006] Various methods can be used for structuring within a glass substrate, for example to create openings.

[0007] In addition to water and sandblasting using appropriate masks, ultrasonic lapping is an established process. However, these methods are limited in scale to small structures, which are typically around 400 pm for ultrasonic lapping and a minimum of 100 pm for sandblasting. Due to the mechanical removal, water and sandblasting create stresses in the glass, which lead to chipping at the hole edge. Neither process is generally suitable for structuring thin glass. These processes are also unsuitable for structuring the surface of glass substrates due to their predetermined erosion direction and the rough processing involved.

[0008] Therefore, the use of laser sources for structuring a wide variety of materials has recently become established. A wide variety of solid-state lasers, operating at infrared (e.g., 1064 nm), green (532 nm), and UV (365 nm) wavelengths, or even extremely short wavelengths (e.g., 193 nm, 248 nm), allow smaller structures to be introduced into a glass substrate than is possible with the aforementioned mechanical processes. However, since glass has low thermal conductivity and is also highly susceptible to fracture, laser processing can also lead to high thermal stress on the glass during the production of very fine structures, resulting in critical stresses and even microcracks and deformations in the edge areas of holes. In addition, burrs or other raised areas often form on the surface of the substrates.Such elevations, however, are a major disadvantage, especially with regard to stacked components, as flat stacking can no longer be guaranteed. The process is therefore only suitable to a limited extent for use in the industrial production of stacked substrates. This particularly applies to components or substrates that require a defined topography, especially on their surface. For example, stacked substrates that are to be arranged between other components require structures that are as flat and even as possible in order to minimize the distances between the individual layers arranged on top of one another. This is the case, for example, with laser-welded multi-layer components or component assemblies that are to be joined together using anodic bonding.

[0009] However, the distance that these components can provide is determined by the manufacturing process, so that it is only possible to prevent or remove burrs and fine structures in order to create surfaces that are as flat as possible, with very high technical and financial effort and through many different process steps.

[0010] The object of the invention is therefore to provide a glass substrate with a defined surface structure, a particularly flat surface, and fine structures extending throughout the volume of the substrate. Furthermore, such a component should be able to be produced with significantly less effort and thus more cost-effectively using an optimized process for producing defined, flat or particularly flat microstructures with a narrow size tolerance.

[0011] This problem is solved by the subject matter of the independent claims. Advantageous further developments are specified in the respective dependent claims.

[0012] Accordingly, the invention relates to a plate-shaped glass element having a first surface and a second surface arranged opposite the first, as well as at least one recess that penetrates at least one of the surfaces. The recess extends in a longitudinal direction and a transverse direction, and the longitudinal direction of the recess is arranged transversely to the surface penetrated by the recess. The surface penetrated by the recess has at least one of the following features:

[0013] - the surface has at least one height deviation relative to the surface, at least partially around the recess, wherein the amount |Ah| of the height deviation, in particular with respect to a depth or a height, is preferably greater than 0.005 gm, preferably greater than 0.05 gm and / or less than 0.1 gm, preferably less than 0.3 gm, preferably less than 0.5 gm,

[0014] - the surface penetrated by the recess has a mean roughness value of less than 15 nm,

[0015] - an edge between the surface and the recess is formed without any elevation.

[0016] Preferably, the surface is so flat that a further component, in particular with a flat surface, can be arranged on the glass element at a distance of less than 500 nm, preferably less than 250 nm, preferably less than 100 nm. The height deviation can comprise depressions that have a depth of less than 100 nm, preferably less than 50 nm, preferably less than 5 nm, relative to the surface of the glass element, or elevations that have a height of less than 100 nm, preferably less than 50 nm, preferably less than 5 nm.

[0017] These features offer several advantages. Particularly flat surfaces, or those with depressions that run around the recess, enable the arrangement of several (plate-shaped) glass elements on top of one another and, in particular, a surface connection of these glass elements, for example by means of anodic bonding, laser welding (e.g., USP laser welding) or other methods. The height deviation can be understood to be a deviation from a zero plane of the glass element, wherein the zero plane can in particular be defined such that it covers at least 51% of the entire first and / or second surface, preferably at least 70%, particularly preferably at least 90%, preferably at least 95%. Thus, one or more height deviations can be formed with respect to the zero plane, which are higher and / or lower relative to the zero plane.The height deviations can preferably also be annular or run in a ring shape around the recess, for example as an open ring.

[0018] Alternatively, the zero plane can be calculated by constructing an evaluation line around a single feature at a selectable distance in all directions from its perimeter (similar to a dilation), creating a new line of similar shape but with a larger area and perimeter. The average profile height / thickness is determined along this evaluation line. The reference height / thickness is determined by repeating this process at increasingly larger distances from the original perimeter of the feature, as a limit for large distances.

[0019] The longitudinal direction is a direction that runs from one side of the glass element to the other. The longitudinal direction can therefore also be referred to as the thickness direction or the through-flow direction. Since the extent of a recess in the longitudinal or thickness direction is limited by the thickness of the glass element, the dimensions of the recess in the transverse direction are usually larger than in the longitudinal direction, especially in thin glass elements.

[0020] A surface roughness (Ra) of less than 15 nm is particularly advantageous, as this not only makes the glass element particularly suitable for the close spacing of multiple stacked elements, but also allows it to have a smooth surface, which is required for certain optical applications, or, for example, minimizes resistance to friction from other components or substances such as fluids. Furthermore, a particularly flat surface ensures that the distance between the glass element and another component is uniform.

[0021] Preferably, the height deviation has at least one of the following features:

[0022] - the height deviation encloses the recess at least partially, but preferably completely,

[0023] - the height deviation is designed as a shortening of the wall of the recess,

[0024] - an inner surface of the height deviation is at an obtuse angle to the first surface pierced by the recess(es),

[0025] - the height deviation is designed as a depression around the recess,

[0026] - the height deviation has lateral dimensions which are greater than 5 pm, preferably greater than 8 pm, preferably greater than 10 pm and / or less than 5 mm, preferably less than 3 mm, preferably less than 1 mm.

[0027] It can also be provided that the height deviations have a depression with a depth that runs parallel to the longitudinal direction of the recess(es), and in particular transversely to the first and / or second surface. In this way, a gap is created between a depression base and the first and / or second surface of the glass element, which gap can serve, for example, for a fixing material, such as an adhesive material, which can fix an element that can be arranged in the recess. In this way, for example, several glass elements can be arranged planarly on top of one another despite the adhesive material, so that excess adhesive material can find space in the depression or height deviations.

[0028] In an advantageous embodiment, the glass element has a thickness that is greater than 10 μm, preferably greater than 15 μm, preferably greater than 20 μm and / or less than 4 mm, preferably less than 2 mm, preferably less than 1 mm. Such a thickness makes it possible to stack several glass elements on top of one another without requiring much space. Furthermore, the glass element can be made flexible due to its low thickness, so that it can be bent. Since other binding forces often play a significant role due to a low thickness, the glass element can also be made more mechanically stable against externally applied mechanical stress. These advantages allow the glass element to be used, for example, in IC housings, biochips, sensors such as pressure sensors, camera imaging modules and diagnostic technology devices.

[0029] In a further embodiment, the glass element has a transverse dimension greater than 5 mm, preferably greater than 50 mm, preferably greater than 100 mm and / or less than 1000 mm, preferably less than 650 mm, preferably less than 500 mm. With such dimensions, the glass element can be optimally used as a component for microtechnology.

[0030] It is also advantageous if the recess is designed as a channel that extends through the glass element from the first surface to the second surface and breaks through both surfaces. A recess that runs through the glass element has the advantage that entire structures or multiple recesses can run through the glass element. Preferably, multiple recesses or channels are arranged directly next to one another in a row so that a larger recess is formed, the size of which is determined at least by the sum of the sizes of the individual recesses arranged next to one another. Ideally, the wall has dome-shaped depressions. The size or extent of the larger recess can, however, also be larger than the sum of the recesses arranged next to one another.The width or transverse extent of the recesses can extend parallel to the first and / or second surface, and the longitudinal direction or depth of the recesses can be formed perpendicular to the first and / or second surface of the glass element. In this way, the glass element can have any number of, and in particular any size, recesses, the transverse extent of which preferably runs perpendicular to the depth of the recesses. By inserting the channels or continuous recesses, if these are produced next to one another, the glass element can also have perforations, so that, in particular, parts of the glass element can be removed or separated.

[0031] It is also conceivable for an edge to be formed by a plurality of openings extending through the glass element from the first surface to the second surface and directly adjacent to one another. The edge forms an outer edge of the glass element that at least partially surrounds the glass element and / or an inner edge of the glass element that at least partially surrounds the recess. The edge further comprises a plurality of dome-shaped depressions. Preferably, a depth of the depressions is aligned transversely to the depth of the recess and / or the thickness of the glass element. It is also conceivable for a height of the edge to correspond to the thickness of the glass element. The dome-shaped depressions ideally form a special structuring of the edge that offers several advantages.The rounded structures, or calottes, represent a particularly advantageous shape for dissipating tensile stresses occurring at the edge surface down to the deepest points of the edge surface, namely the deepest points of the calottes. This effectively suppresses crack growth at potential defects in the edge surface.

[0032] The edge preferably has a surface proportion with convex-shaped regions that is less than 5%, more preferably less than 2%. Ideally, the surface proportion of concave-shaped regions, i.e. regions with dome-shaped depressions, is greater than 95%, preferably greater than 98% of the edge surface. Concave means that a curvature runs in the direction of the glass element, and convex means that a curvature runs away from the glass element, i.e. in the direction of the recess. The depth of the dome-shaped depressions is typically less than 5 μm, ideally with transverse dimensions of preferably between 5 - 20 μm. It is also conceivable for the edge to correspond to the wall of the recess. Therefore, the inner surface of the height deviation, in particular as a shortening of the wall of the recess, can also have the dome-shaped depressions. In this way, the height deviation and its inner surface are also protected against crack growth.

[0033] Preferably, the glass element has at least one of the following features:

[0034] - The inner edge of the glass element has a plurality of dome-shaped recesses and the first and second surfaces of the glass element are designed to be dome-free,

[0035] - the inner edge of the glass element has a higher mean roughness value (Ra) than the first and second surfaces of the glass element.

[0036] The surface of the glass element can therefore have a different roughness than the inner edge of the recess. Advantageously, the first and second surfaces of the glass element can thus be adjusted to a roughness that differs from the roughness of the inner edge of the recess. In this way, the surfaces of the glass element and the inner edge of the recess can be optimized for different intended applications. Preferably, the roughnesses of the first and second surfaces are adjusted in a common process step, in particular an etching step, with the roughness of the inner edge of the recess.

[0037] It is also advantageous if the recesses have a transverse dimension of 10 pm, preferably 20 pm, preferably 50 pm, preferably 100 pm. However, the transverse dimensions of the recess can also be greater than at least 150 pm, preferably greater than 500 pm, or even up to 50 mm, so that, for example, other components, such as electronic conductors or piezoelectric components, can also be installed in the recesses. Such dimensions are particularly advantageous in the intended application field of microsensor technology.

[0038] The object is also achieved by a method for modifying a surface of a plate-shaped glass element, according to which the glass element has a first surface and a second surface arranged opposite the first, as well as at least one recess that penetrates at least one of the surfaces. The recess extends in a longitudinal direction and a transverse direction, and the longitudinal direction of the recess is arranged transversely to the surface penetrated by the recess. Preferably, a wall of the recess has a plurality of dome-shaped depressions, wherein in the method:

[0039] - the glass element is provided,

[0040] - at least one filament-shaped channel is created in the glass element by a laser beam of an ultrashort pulse laser, and a longitudinal direction of the channel runs transversely to the surface of the glass element,

[0041] - the surface of the glass element which is penetrated by the channel is exposed to an etching medium which removes glass of the glass element at an adjustable removal rate, whereby the channel is widened by the etching medium so that a recess is formed,

[0042] - wherein the etching produces at least one of the following features of the surface which is penetrated by the recess: o the surface has at least one height deviation relative to the surface at least partially around the recess, wherein the amount |Ah| of the height deviation (20), in particular with regard to a depth or a height, is greater than 0.005 pm, preferably greater than 0.05 pm and / or less than 0.1 pm, preferably less than 0.3 pm, preferably less than 0.5 pm, o the surface which is penetrated by the recess has a mean roughness value which is less than 15 nm, o an edge between the surface and the recess is formed without elevations.

[0043] It is envisaged that the method can also be used to produce a glass element according to the aforementioned embodiments, so that the aforementioned advantages can be achieved. In a first method step, at least one glass element, in particular without recesses, is provided. In a further, in particular second step, at least one, but preferably several, and particularly preferably a plurality of defects are produced in the glass element in order to ideally be able to form a perforation of the glass element through the defects. For this purpose, several defects are preferably produced next to one another in such a way that a row of recesses represents a larger structure. The defects are in particular designed as a filament-shaped channel and run in their longitudinal direction transverse to a first and / or second surface of the glass element.The channel extends from at least one surface, and in particular perpendicularly from this surface into the glass element, and penetrates at least this surface. Preferably, however, the channel extends from the first to the second surface and penetrates both surfaces.

[0044] The recess(es) is / are created in the glass element using a laser beam from an ultrashort pulse laser. The creation of the recesses using the laser is preferably based on several of the following steps:

[0045] - the laser beam of the ultrashort pulse laser is directed onto one of the surfaces of the glass element and concentrated by focusing optics to an elongated focus in the glass element, whereby

[0046] - the irradiated energy of the laser beam creates at least one filament-shaped damage in the volume of the glass element, and

[0047] - the ultrashort pulse laser radiates a pulse or a pulse packet with at least two or more consecutive laser pulses onto the glass element, and in the process, preferably after the introduction of the filamentary damage, the filamentary damage is widened into a channel.

[0048] - In this way, a large number of channels are produced, the channels, in particular their arrangement on or in the glass element, being selected such that many channels arranged next to one another form an outline of a recess to be produced. The channels can be arranged at a distance from one another that is greater than 2 pm, preferably greater than 3 pm, preferably greater than 5 pm and / or less than 100 pm, preferably less than 50 pm, preferably less than 15 pm. Likewise, a diameter of the channels can vary between 10 pm and 100 pm. In a further step, the surface pierced by at least one channel is exposed to an etching medium. Preferably, the entire glass element, in particular the first and second surfaces, is exposed to this etching medium.It is advantageous if the etching medium is filled into a container, for example a tank, a pot, or a tub, and in particular, one or more glass elements are subsequently held or immersed at least partially in the container or in the etching medium. The container is preferably made of a material that is substantially resistant to the etching medium.

[0049] The etching medium can be gaseous, but is preferably an etching solution. Therefore, according to this embodiment, the etching is carried out wet-chemically. This is advantageous for removing glass components from an inner surface of the channel or a surface of the damage and / or the surface of the glass element, for example, the first and / or second surface, during etching. Glass components can, of course, also be dissolved out at an edge of the glass element by the etching medium.

[0050] Both acidic and alkaline solutions can be used for this purpose. Particularly suitable acidic etching media are HF, HCl, H2SO4, ammonium bifluoride, HNO3 solutions, or mixtures of these acids. Basic etching media, for example, include KOH or NaOH solutions. Ideally, the etching medium to be used is selected based on the type of glass being etched.

[0051] In one embodiment, the removal rate can therefore be adjusted by selecting a combination of glass composition and etching medium composition. For example, for glass with a high calcium content, an acidic etching medium is preferably selected, whereas for glass with a lower calcium content, a basic etching medium is preferably used. This is because an excessively high calcium content, which is dissolved out of the glass by etching, can quickly oversaturate a basic, particularly alkaline, etching medium and thus reduce the etching ability of the etching medium too quickly. On the other hand, the removal rate, i.e. the etching rate, is much higher with an acidic etching medium and a glass with a high silicate content than with a basic etching medium. However, the acidic etching medium is also neutralized much more quickly by the substances already dissolved in it, thus consuming the etching medium or saturated with glass.

[0052] Accordingly, depending on the glass composition, an acidic etching medium can be selected to achieve a rapid removal rate, or a basic, particularly alkaline, etching medium can be selected to achieve a slow removal rate. In general, silicate glasses with a low alkali content are particularly suitable for the inventive modification of a glass surface. Excessively high alkali contents, as previously mentioned, make etching more difficult. According to a further development of the invention, the glass of the glass element is a silicate glass with an alkali oxide content of less than 17 percent by weight, and ideally a borosilicate glass.

[0053] However, to better control the removal, a slower removal rate or a basic etching medium is preferred. This makes it possible to achieve a removal rate of less than 7 pm / h, preferably less than 5 pm / h, preferably less than 4 pm / h, preferably less than 3 pm / h and / or greater than 0.3 pm / h, preferably greater than 0.5 pm / h, preferably greater than 1 pm / h, preferably greater than 1.5 pm / h, and in particular between 2 pm / h and 2.5 pm / h. Such a removal rate advantageously allows sufficient time to influence the etching medium or the etching process even during the etching process.

[0054] In one embodiment, the removal rate can also be adjusted using additives. For example, substances from the following group can be used individually or in combination: surfactants, complexes or coordination compounds, radicals, metals, and / or alcohols. Additives enable even more precise control of the etchability of the etching medium and, in particular, targeted control of the etchability for specific glasses or specific glass compositions.

[0055] The etching is preferably carried out at a temperature higher than 40°C, preferably higher than 50°C, preferably higher than 60°C and / or lower than 150°C, preferably lower than 130°C, preferably lower than 110°C, and in particular up to 100°C. This temperature provides sufficient mobility of the ions or components of the glass of the glass element to be dissolved from the glass matrix.

[0056] Another factor is time. For example, a higher material removal can generally be achieved if the glass element is exposed to the etching medium for several hours, in particular longer than 30 hours. On the other hand, it is possible to limit the material removal by exposing the glass element to the etching medium for less than 30 hours, for example only 10 hours. In general, at least one of the above-mentioned features of the glass element is created by introducing damage and channels, as well as by adjusting the removal rate or the etching medium depending on the temperature, the composition of the etching medium, the duration of the etching, and the composition of the glass of the glass element. For example, by setting a higher removal rate, in particular above 2 pm per hour, an average roughness (Ra) of below 15 nm can be achieved.In this way, the formation of raised areas can be deliberately avoided, resulting in a particularly smooth surface of the glass element. On the other hand, a particularly high removal rate can also create depressions, especially in the recess area, since the surface area is higher there and the etching medium has a correspondingly larger "surface area" available.

[0057] It can also be provided to shield defined areas of the glass element from the etching medium. This can be achieved, for example, by using special holders with which the glass element is held in the volume of the etching medium. Furthermore, special shaped elements are conceivable which are arranged on the glass element before it is exposed to the etching medium. It is also possible to apply a protective layer, for example a polymer layer, to the glass element before it is exposed to the etching medium. It is possible for the protective layer to be applied over the entire area of ​​the first and / or second surface. The protective layer can then be at least partially removed again, for example by the laser if the protective layer was already applied before the structuring process using the laser, so that the protective layer is removed in particular in the area of ​​the recess.Thus, defined areas of the glass element can be covered by holders, shaped elements, and / or protective layers, thus shielding the glass element from the etching medium. These holders, shaped elements, and / or protective layers therefore preferably comprise a material that is resistant to the etching medium. In this way, the holders, shaped elements, and / or protective layers are not attacked by the etching medium. It is also conceivable to shield the entire first and / or second surface of the glass element by means of holders, shaped elements, and / or protective layers, leaving only those areas exposed in which recesses are created, or in which damage or channels were created by the laser.In this way, it is conceivable to design the first and / or second surface essentially free of elevations, so that in particular a mean roughness value (Ra) of less than 40 nm, preferably less than 25 nm, is produced, and thus a particularly smooth surface. Furthermore, it is conceivable for one of the surfaces to be completely shielded from the etching medium, and the other surface to be completely, or at least partially, exposed to the etching medium. In this way, for example, a raised structure can be produced on one surface. In other words, the glass element in this case only has height deviations in the form of elevations on one surface, while the other surface remains free of elevations. Another possibility, of course, is for the first and second surfaces to be shielded, and only the damage and / or channels to be exposed to the etching medium. In this way, both surfaces can be designed to be particularly flat or planar.

[0058] In an advantageous embodiment, the etching medium or the etching process removes so much material from the glass element that adjacent channels or damages merge, thus creating the recesses. Preferably, the walls between the channels or damages are removed by the etching medium, forming a continuous edge. Furthermore, this edge ideally has dome-shaped depressions. The edge can be formed, for example, as an outer edge of the glass element that at least partially surrounds the glass element, or as an inner edge of the glass element that at least partially surrounds the recess. In this way, large portions of the glass element that were surrounded by adjacent channels in the form of a structure prior to the etching process can be removed.

[0059] In addition, ribs could be created on the edge to provide mechanical support or act as crack inhibitors. The ribs are preferably arranged between two channel centers. It is also conceivable that the depth, size, or dimensions of the caps can be changed by specifically adjusting the removal rate. For example, a higher removal rate can result in flatter and wider caps, so that the surface or edge of the glass element can be made smoother. Overall, the method according to the invention has the advantage that not only can recesses of any shape and size be created, but the surface(s) of the glass element can also be treated or machined in the same method step. This makes it possible to create recesses and produce a smooth surface with a low mean roughness at the same time.The process therefore not only avoids process steps, but also considerable additional costs due to any subsequent processing of the glass.

[0060] It is also envisaged that the etching medium is set in motion in such a way that the removal rate is accelerated or reduced by the movement of the etching medium. The movement of the etching medium represents a further possibility for influencing and, in particular, controlling the removal rate. By means of movement, for example, used or saturated etching medium or etching residues can be specifically transported away from the regions of the glass element to be etched and preferably replaced with unused, fresh etching medium. In this way, the removal rate or etching speed can be considerably accelerated. On the other hand, it is also conceivable that movement of the etching medium is deliberately prevented, for example by means of partition walls in the container. In this way, used etching medium can no longer be transported away, so that the removal rate is noticeably reduced.However, it is preferred that the etching medium be set in motion, thus increasing the removal rate. Preferably, this movement can be induced mechanically. However, it is also conceivable to set the etching medium in motion by another physical means. Preferably, at least one of the following options is selected in the course of the method according to the invention:

[0061] - The movement is generated by sound waves, particularly ultrasonic waves. A sound wave source can be arranged below and / or to the side of the container containing the etching medium and the glass element. A sound wave source has the advantage that only one sound wave source is sufficient to set the entire volume of the etching medium, particularly the etching solution, in motion. The generated waves spread across the entire solution volume without any further intervention and are preferably only slightly attenuated, allowing the etching medium to be moved uniformly.

[0062] - The movement is generated by magnetic stirrers or magnetic fields, which are preferably located below the container. The magnetic fields set, for example, magnetic stirrer bars in a, ideally rotational, motion. The magnetic stirrers or magnetic stirrer bars are located within the etching medium and can therefore directly set the etching medium in motion through their rotational movement.

[0063] The advantage of magnetically induced movement or magnetic stirrer bars is that the speed of the rotational movement and thus the movement of the etching medium can be very well controlled. In this way, for example, a fast or slow stirring movement can be introduced into the etching medium. Furthermore, several magnetic stirrers can be controlled separately. In the case where several glass elements are in the container and the etching medium at the same time, different rotational speeds and thus locally different movements and removal rates can be set by controlling the magnetic stirrers separately. In this way, for example, several glass elements can be etched or processed simultaneously at different speeds. It is of course also conceivable for the stirring bars to be designed as stirring units and to be moved not magnetically, but in particular mechanically.These stirring units can also be easily immersed into the etching medium from the direction of a container opening for stirring purposes.

[0064] - The movement is generated by holding the glass elements in place, or the holders that hold the glass elements in the etching medium are mechanically set in motion. This causes the glass element to move back and forth in the etching medium, creating an effect similar to that described above. - The movement is generated by a vibrating table, or the container, together with the etching medium and the glass element, is set in motion, for example, by placing the container on a vibrating table. This ensures a uniform movement of the etching medium throughout the entire container.

[0065] - The movement is generated by convection of the etching medium. A heat source can be located underneath or on the side of the container. Due to the one-sided heating, the heated etching medium rises, while cooler etching medium falls away at another location, creating continuous convection. This allows for particularly slow movements, which lead to a reduced removal rate.

[0066] - The movement is induced by fluids, which are introduced into the etching medium, for example, through nozzles. Such nozzles can be arranged on the container. This preferably creates a bubbling effect, which sets the etching medium in motion.

[0067] In an advantageous embodiment, the etching medium is modified in at least one defined area on the surface of the glass element, and the removal rate in this area is changed relative to surrounding areas. This means that the removal rate can be locally changed. Advantageously, elevations with heights of more than 0.5 pm and / or depressions with a depth of more than -0.5 pm can be specifically avoided in individual or multiple recesses. There are several ways to locally modify the etching medium. However, one of the following solutions is preferred within the meaning of the invention:

[0068] - In the area of ​​recesses, edges, channels, and / or damage, there are more open bonds in the glass material. In addition, there is a larger surface area available for reaction with the etching medium. This preferably results in a short-term acceleration of the material removal rate, or in more material being removed in a shorter period of time than on a flat surface of the glass element. This preferably leads to the etching medium being used up comparatively quickly in the area of ​​recesses, edges, channels, and / or damage, or to a significant reduction in its etching ability. Such an effect - a temporary change in the removal rate at recesses and edges - can also be used to locally change the removal rate and preferably also the etching medium by specifically modifying the surface at damages, channels, recesses, and / or edges using a laser.For example, it is conceivable to create a smoother or more even surface of the damage and / or channels by selecting a pulse packet with fewer pulses per pulse packet, such as 2 or 3, so that the etching medium is consumed or neutralized more slowly. For this reason, the etching medium can be modified not only locally in the area of ​​recesses and edges, but also on surfaces, especially the inner surfaces of recesses and / or edges.

[0069] Locally adding fresh etching medium and / or additives. It is also possible to add fresh etching medium or additives to the etching medium by locally adding such substances, particularly by dripping them into the etching medium, via a dosing unit, such as a tap. This not only allows the etching medium to be locally modified but also sets it in motion. This allows the removal rate to be further modified, especially in a controlled manner, and preferably accelerated.

[0070] Another possibility for locally modifying the etching medium is the material used to mount the glass elements or the container. By carefully selecting the material, for example, the container, material removal-promoting ions, such as metals, or material removal-inhibiting ions, such as alkalis, can be released into the etching medium, thus controlling the material removal rate. In this way, it is possible for material removal-promoting or material removal-inhibiting ions to be released directly from the material used to mount the glass element or the container, influencing the etching medium and its etching ability. It is also advantageous to adjust the material removal rate by creating a spatial and / or temporal temperature gradient.Since temperature influences the mobility of the material components, and in particular the components that can be dissolved out of the material during the etching process, a change in temperature can also advantageously alter the removal rate or the reaction rate of the glass element with the etching medium. For example, a temporal temperature gradient can be easily controlled by a temporally defined variation of the temperature. The generation of a spatial temperature gradient is particularly advantageous when, for example, several glass elements are to be etched separately at different removal rates. A spatial temperature gradient can be generated in various ways. One of the following options is preferred:

[0071] - A spatial temperature gradient can be created between a container wall and an interior region of the container. In this case, the container or the etching medium is heated evenly, i.e., the volume of the etching medium is uniform. The etching medium is preferably cooled by the container wall. This cooling can be enhanced if the container or the container wall comprises a material with high thermal conductivity, for example, a metallic material. This dissipates the heat of the etching medium more quickly, thereby passively cooling it. However, it is also conceivable for the container wall to be actively cooled by a cooling medium, for example, water. To save process costs, however, a thermally conductive container is preferred. This also offers the advantage of not incurring any additional process costs, meaning the temperature gradient can be created simply and cost-effectively.

[0072] - Another possibility is a heat source located locally on a container wall. The heat source can be located to the side, above, and / or below the container. The temperature gradient is then formed concentrically around this heat source, so that the temperature decreases with increasing distance from the heat source.

[0073] - A particular embodiment of generating the spatial temperature gradient is achieved by locally directing electromagnetic radiation, preferably a laser beam, onto the etching medium or a surface area of ​​the glass element. This enables, in particular, the formation of a small-scale temperature gradient. This makes it possible to generate a temperature gradient that, for example, covers only a few pm and can therefore have a very local effect. This has the advantage that the temperature-induced change in the removal rate or the etching medium can be limited to defined areas of the glass element, for example, individual recesses. In this way, elevations on or around individual recesses can preferably be individually created or prevented.

[0074] - Another option is to heat the glass element mounts. Heating the mounts, and thus preferably also the shielding elements, allows the removal rate to be adjusted, particularly in areas directly adjacent to areas shielded by the mount. This makes it possible to control or increase the removal rate in areas where, for example, the surface is partially obscured by the mounts, allowing more glass to be removed there.

[0075] - Another possibility for generating a spatial temperature gradient is the generation of voltage arcs, or at least a voltage arc between two electrodes that can be placed at suitable locations in the etching medium. In the area of ​​these voltage arcs, the etching medium is then locally heated and, in particular, set in motion.

[0076] However, the removal rate can also be adjusted by a special spatial arrangement of the glass element within the etching medium, in particular with regard to gravity or a direction of movement of the etching medium. In order to accelerate the removal rate within the recess, for example, the longitudinal direction of the recess in the glass element can be aligned parallel to the direction of movement of the etching medium. The surface of the glass element is then aligned transversely or perpendicular to the direction of movement of the etching medium. This alignment ensures that the etching medium is moved through the recess. This allows, for example, etching medium saturated by dissolved glass to be transported out of the recess, whereby a consistently high removal rate within the recess can be achieved over time, since neutralized etching medium does not remain within the recess and, in particular, fresh, unsaturated etching medium is always available.

[0077] However, if the etching medium is not actively set in motion, e.g. by one of the aforementioned means, the removal rate in the area of ​​the recess or edge of the glass element is initially increased due to a higher surface area relative to the surface of the glass element. However, the removal rate also decreases significantly more quickly in relation to the surface of the glass element in the area of ​​the recess because the etching medium is saturated or neutralized more quickly. As the saturation of the etching medium increases, the density and thus, in particular, the weight of the etching medium also increases due to the dissolved glass material. The heavy etching medium can also sink out of the recess if the longitudinal direction of the recess is oriented in the direction of gravity. This can lead to an elevation being formed at least partially around the recess and preferably in the direction of gravity or the sinking direction of the saturated etching medium.The saturation of the etching medium can lead to the removal rate being reduced at least partially around the recess and preferably in the direction of movement of the saturated etching medium, thereby forming an elevation.

[0078] Conversely, however, an increased removal rate can be generated on the side opposite the sinking direction or movement direction, since fresh etching medium is continuously supplied there. Therefore, in particular, simply by aligning the glass element or the recess within the etching medium, not only can a movement of the etching medium be induced, but the removal rate can also be influenced, preferably in the area of ​​the recess.

[0079] It is therefore intended to align the glass element within the etching medium, and in particular with respect to a direction of movement of the etching medium, in such a way that etching medium with a high glass concentration is transported away at the intended locations to avoid elevations and / or the creation of depressions or to reduce the heights / depths of elevations and depressions. For this purpose, the glass element or the surface(s) of the glass element can be aligned, for example, with respect to a container bottom and / or a direction of movement of the etching medium, e.g., the sinking direction or the flow direction, at an angle between 0° (parallel) and 360° (parallel), preferably between 90° (vertical) and 270° (vertical). An angle of approximately 180° is also conceivable.

[0080] Other angles may also be advantageous, for example a particularly oblique angle of the glass element relative to the direction of movement of the etching medium, preferably between 10° and 80°, more preferably between 20° and 70°, particularly preferably between 30° and 50°. The removal rate, particularly in the region of the recess, can also be controlled by the thickness of the glass element or the length of the recess. As previously described, the etching medium saturates more quickly in the region of the recess and / or the movement of the etching medium is restricted by the narrower confines of the recess walls. Both lead to a reduced removal rate in the region of the recess compared to the removal rate at the surface of the glass element. Accordingly, a concentration gradient exists between the region of the recess or within the recess and an area on the surface of the glass element, and in particular also a temporal gradient of the removal rate.By changing the length of the recess, i.e., the thickness of the glass element, the movement of the etching medium in the region of the recess can be changed accordingly, and thus, in particular, the concentration gradient or the degree of saturation of the etching medium in the region of the recess. By appropriately selecting the orientation of the glass element, as well as preferably other parameters such as the movement of the etching medium and / or a temperature gradient, it is also possible, for example, to form a ridge or protrusion on the edge of one side of the glass element while avoiding a ridge or protrusion on the opposite side.

[0081] Preferably, a height deviation is avoided as best as possible, or at least generated or adjusted to a value of less than ± 0.5 pm with respect to the surface of the glass element by a removal rate that is / was accelerated by one of the aforementioned embodiments, for example by rolling. In the sense of the invention, it is preferred that the first and / or second surface is formed at least around a recess, but in particular completely free of elevations, and preferably additionally has a mean roughness (Ra) that is less than 15 nm. Ideally, the removal rate is increased in particular by setting the etching medium in motion. Ideally, the movement is achieved by stirring the etching medium and / or generating a temperature gradient. In this way, a flat glass element with a particularly smooth surface and in particular a low mean roughness can be produced.Only a few process steps are necessary, as the surface of the glass element does not need to be further treated after the etching process.

[0082] The glass element according to this disclosure can be used, among other things, for the manufacture of components for the hermetic packaging of electro-optical devices, microfluidic cells, pressure sensors and camera imaging modules.

[0083] The invention is explained in more detail below with reference to the accompanying figures. In the figures, like reference numerals designate like or corresponding elements. They show:

[0084] Fig. 1 Schematic representation of the generation of damage in the glass element by a laser;

[0085] Fig. 2 Schematic representation of a glass element with multiple damages;

[0086] Fig. 3 Schematic representation of an etching process of the glass element;

[0087] Fig. 4 Schematic representation of the glass element at advanced etching stage;

[0088] Fig. 5 Diagram of the mean roughness of the surface of the glass element after etching under different conditions;

[0089] Fig. 6 Diagram with measurement data of the removal rate as a function of the glass concentration;

[0090] Fig. 7 Schematic representation of an etching process of several glass elements in a container with a moving etching medium; Fig. 8 Measurement results of the height deviation as a function of the temperature of the etching medium and the orientation and shape of the recess;

[0091] Fig. 9 Diagram of the depth of the height deviation 20 in dependence of the

[0092] Temperature of the etching medium 200 and an up and down movement of the glass elements during the etching process,

[0093] Fig. 10 Topography of a glass element after etching;

[0094] Fig. 11 A glass element in plan view with symmetrical height deviation and height profile of the height deviation.

[0095] Fig. 1 schematically shows a glass element 1 with a first 2 and a second 3 surface, and a thickness D. The first surface 2 is arranged opposite, and in particular preferably plane-parallel to, the second surface 3. 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 side surface 4, which ideally surrounds the glass element 1 and whose height corresponds to the thickness D of the glass element 1. Ideally, the thickness D of the glass element 1 and the height of the side surface 4 extend in the longitudinal direction L. The first 2 and second 3 surfaces can further extend in the transverse direction.

[0096] In a first method step, damage, in particular channels 15 or channel-shaped damage 15, is generated in the volume of the glass element 1 by a laser 101, preferably an ultrashort pulse laser 101. For this purpose, the laser beam 100 is focused by means of a focusing optics 102, for example a lens or a lens system, and directed onto a surface 2, 3, preferably the first surface 2 of the glass element 1. By focusing, in particular a prolonged focusing of the laser beam 100 onto an area within the volume of the glass element 1, the energy radiated by the laser beam 100 ensures that filament-shaped damage is generated, which, for example, widens the damage into a channel 15 through multiple laser pulses, for example in the form of a pulse packet.

[0097] Preferably, as shown in Figure 2, several channels 15 are created in further steps, which are ideally arranged next to one another such that a plurality of channels 15 results in a perforation, and this perforation or this plurality of channels forms the outlines of a structure 16. Ideally, a structure 16 created in this way corresponds to the shape of a recess to be created. In other words, a spacing and a number of channels 15 are selected such that outlines of recesses to be created are formed.

[0098] Figure 3 shows a further step. The glass element 1 is detachably arranged on holders 50. The glass element 1 can simply rest on the holders 50 or be fixed to them. Preferably, certain areas of the holders 50 serve to cover or shield defined areas of the glass element 1. However, other elements, for example one or more polymer layers or shaped elements, can also be used for this purpose. The areas covered by the holders, the polymer layer(s) and / or the shaped elements preferably serve as a mask for a raised structure to be created on the surface 2, 3 of the glass element 1. Equally, however, it is also conceivable for the first and / or second surface 2, 3 to be completely shielded in order to avoid a raised structure on the surface of the glass element and to create at least a particularly flat or planar surface.It is certainly also possible to cover such areas before the laser 101 is used. The covered areas should continue to function as shielding against an etching medium to which the glass element 1 will be exposed in a subsequent step.

[0099] For this purpose, the glass element 1 is held, and in particular immersed, in an etching medium 200, preferably an etching solution, by means of the holders 50. The etching medium 200 is preferably arranged in a container 202. Ideally, the container 202 comprises a material that is substantially resistant to the etching medium 200. Preferably, the container comprises a material capable of releasing certain elements or substances, for example, certain ions or molecules, into the etching medium 200. Ideally, these substances released by the container 202 change the etching ability of the etching medium 200 in such a way that the removal rate of material from the glass element is accelerated or reduced.

[0100] Preferably, an acidic or alkaline solution is used as the etching medium 200, and in particular an alkaline solution, for example, KOH. Ideally, the etchability of the etching solution is influenced by the material of the container 202, as well as possibly also by additives added to the etching solution. By exposing the glass element to the etching medium 200, material from the glass element is removed, resulting in a removal rate 70, which can be influenced by several factors.

[0101] A first factor is the temperature at which the glass element 1 is etched. The etching process is preferably carried out at a temperature between 60°C and 130°C, ideally at approximately 100°C, with a temperature gradient preferably being created by a container wall that is cooler than the heat source.

[0102] In addition, the removal rate is preferably influenced, in particular accelerated, by setting the etching medium 200 in motion. For this purpose, one or more stirring units 60 can be used, for example. It is conceivable that mechanically or electronically operated stirring units 60, for example stirring rods, or magnetic stirrers controlled by a magnetic field, are used. Ideally, the stirring units 60 are operated in such a way that they execute a rotary motion, thereby setting the etching medium in motion.

[0103] In a further embodiment, the container 202 can be divided into several regions, for example by means of at least one dividing wall. In this case, a dividing wall 51 is preferably used, which divides the container 202 into two regions. In a first region, for example, one or more stirring units 60 can be arranged, and in a second region, one or more glass elements 1 are preferably arranged. In this case, the dividing wall 51 preferably has one or more passages which connect the first region to the second region in such a way that an exchange of the etching medium 200 through the passages is enabled. In this way, the etching medium 200 can be set in motion in a targeted manner; in particular, a defined flow direction of the etching medium 200 can be realized or controlled as a result.

[0104] Fig. 4 schematically shows the etching process from Fig. 3 at a more advanced stage. The etching medium 200 was set in motion. This enabled the etching medium 200 to be neutralized more quickly in areas where the removal rate was increased, so that the etching medium 200 is consumed in these areas. Such a consumed etching medium 201 is shown in Fig. 4 in the area of ​​the first 2 and second surface 3. This essentially concerns the area of ​​the channels, but can also concern specific areas of the first 2 and / or second 3 surface. In this case, channel walls of several channels were preferably removed to such an extent that several channels were combined, thereby creating the recess 10.

[0105] The example in Fig. 4 shows a glass element 1 in which height deviations 20 in the form of depressions were created by etching, wherein the height deviations were / are preferably formed around the recess 10. The height deviation 20 has a surface 22 that is at an obtuse angle to the surface 2, 3 of the glass element. Furthermore, the recess 10 has an inner recess surface 12 that is preferably defined such that the inner recess surface 12 completely surrounds the recess 10 in at least two spatial directions. The recess 10 can extend in the longitudinal direction L and the transverse direction Q, and in particular form a length that extends along the longitudinal direction L and transversely to the first 2 and / or second 3 surface. It is possible for the length of the recess 10 and a depth H1 of the height deviation 20 together to correspond to a thickness D of the glass element 1.However, it is equally possible that the length of the recess 10 corresponds to the thickness D. Furthermore, the recess 10 forms an edge 40, in particular in the region of the recess inner surface 12, which has dome-shaped depressions.

[0106] Fig. 5 shows a measured mean roughness (Ra) of the surface of the glass element 1 on the ordinate axis as a function of the removal on the abscissa axis under different etching conditions. The respective etching conditions are represented by the different measurement results. • The measurement results shown as empty black rings represent an etching process in which the etching medium 200 was set in motion, in particular by at least one stirring unit 60. Furthermore, a container 202 was used, which preferably comprises a metallic material.

[0107] • The measurement results shown as solid black circles represent an etching process in which the glass element 1 was at least partially shielded from the etching medium 200, preferably by a polymer layer, specifically perfluoroalkoxy polymers. Furthermore, the etching medium 200 was not actively set in motion.

[0108] • The measurement results displayed as patterned black rings represent an etching process in which the glass element 1 was at least partially shielded from the etching medium 200, preferably by a polymer layer, specifically perfluoroalkoxy polymers. Furthermore, a container 202, preferably made of a metallic material, was used, and the etching medium 200 was not set in motion.

[0109] Considering these results, it is noticeable that the surface 2, 3 of the glass element 1 exhibits a particularly low mean roughness after an etching process in which the etching medium 200 is set in motion. This mean roughness is preferably between 2 nm and 10 nm, so that the glass element exhibits a particularly smooth surface 2, 3, and the movement of the etching medium 200 preferably leads to a very low mean roughness. Furthermore, it is noticeable that the material removal, at less than 10 pm, is also very low under these conditions, or only a small amount of removal is necessary to produce a low mean roughness.

[0110] Furthermore, it can be seen that the use of a shield against the etching medium leads to a significantly higher mean roughness, and thus to a significantly rougher and / or more matte surface 2, 3 of the glass element. In other words, the glass element 1 has a significantly rougher surface after an etching process without movement of the etching medium 200 than after an etching process with movement of the etching medium 200. Preferably, the mean roughness after an etching process with a moving etching medium 200 is between approximately 5 nm and 130 nm. Since a container 202 containing a metallic material was used in several cases, i.e., both with and without movement of the etching medium 200, this appears to have a minor effect on the roughness of the surface 2, 3.

[0111] Fig. 6 shows measurement data of the removal rate R e[gm] as a function of the glass concentration c [g / l] in the etching medium 200 in the recess area for three different glasses from SCHOTT with their respective product names listed in parentheses: GlassA (Boro33), GlassB (AF32), and GlassC (D263). The diagram illustrates that a removal gradient develops during removal or etching. Particularly with GlassA and GlassC, the removal rate initially increases moderately and then sharply, with a simultaneous increase in the glass concentration in the etching medium 200. As soon as a certain concentration value is reached, i.e. the etching medium reaches a certain saturation, the removal rate decreases for all three glasses. Particularly with GlassC, it is clearly evident that the removal rate drops to a roughly constant low value after saturation is reached.This can be explained by the fact that the glass concentration in the etching medium 200 initially increases sharply in the region of the recess 10, and the etching medium 200 with the high glass concentration subsequently remains in the region of the recess 10 or is not transported away. This is likely due to a density of the glass-enriched etching medium 200 that is comparable to a density of the etching medium 200 with a low glass concentration. As a result, the etching medium 200 does not move or moves only slightly in the region of the recess 10, so that the etching medium 200 with the high glass concentration is not transported away. The glass concentration of the etching medium is therefore higher in the region of the recess than at the surface 2, 3 of the glass element.

[0112] The situation is different for GlassB and GlassC. After the removal rate reaches a high value and initially decreases again with increasing glass concentration, the removal rate increases again after reaching a low value. This can be explained by the fact that the glass-enriched etching medium 200 in GlassB and GlassC has a higher density and is therefore heavier than the etching medium 200 with a low glass concentration. The etching medium 200 with a high glass concentration therefore sinks out of the area of ​​the recess 10 (when the surface of the glass element is aligned parallel to a container bottom), allowing fresh etching medium 200 to enter the area of ​​the recess. The fresh etching medium 200 then allows an increasing removal rate, which decreases again as soon as the glass concentration of the etching medium reaches a critical value again.Overall, this effect can be used to specifically control the removal rate and set a desired removal rate gradient, for example, by aligning the glass element 1 accordingly in the etching medium 200 or by moving the etching medium 200 in a defined direction. In this way, regions with low glass concentration can be specifically created, where depressions preferentially form due to the increased removal rate.

[0113] In other words, the formation of height deviations 20, their height or depth and / or their shape can be specifically controlled by a defined glass concentration of the etching medium 200 and thus the removal rate, in particular locally.

[0114] In general, the height deviations 20, and in particular a height or depth and / or shape of the height deviations 20, can be significantly influenced by the process parameters, e.g. the removal rate, the composition of the etching medium 200, in particular the glass concentration of the etching medium 200, the movement of the etching medium 200 and preferably a defined flow direction, the duration of the etching process and / or the temperature of the etching medium 200.

[0115] Figure 7 schematically shows a further embodiment. Without being limited to the example shown, a flow direction of the etching medium 200 can be predetermined by means of a divided container 202. In this example, the etching medium 200 is set in motion by means of a stirring unit 60, for example a propeller or magnetic stirrer. The region with the stirring unit 60 can be spatially separated, for example, by a partition wall 51, at least partially from a second region in which the glass element 1 or preferably a plurality of glass elements 1 are arranged, in particular in a holder 50. In the example shown in Figure 7, a plurality of, in particular two, holders 50, each containing a plurality of glass elements 1, are arranged in the second region. The partition wall 51 preferably has one or more passages that connect the first region to the second region in such a way that an exchange of the etching medium 200 through the passages is enabled.In this way, a movement or circulation, in particular convection of the etching medium 200 in the second region can be achieved, wherein the convection is shown as a dashed line.

[0116] The holders are preferably designed such that they can be set in motion, in particular such that the glass elements 1 are movable within the etching medium. For this purpose, two possible movements B1, B2 of the holders 50, or of the glass elements 1, are shown in Fig. 7. B1 shows, for example, an up and down movement of the glass elements 1, or of the holders 50. The glass elements 1 can therefore be moved up and down relative to the container bottom, in particular in constant alternation, for example with a constant frequency and / or a constant distance. The distance of the up and down movement can be varied as desired depending on the length of the glass elements 1, their orientation, and the height of the container 202.

[0117] Another form of movement of the glass elements 1 or the holders 50 is a rotational movement B2. The holders 50 can therefore also be designed such that the glass elements 1 are or are rotated about at least one axis. Preferably, the glass elements 1 are or are also rotatable about a second axis, which is preferably arranged perpendicular to the first axis.

[0118] In general, according to one embodiment, the holder can be moved as a whole along a generally closed, for example, rectangular / polygonal / elliptical, path without rotating about its own axis. This prevents locally different flow velocities of the etching medium from occurring on the glass elements due to rotation, even with such a closed path. In general, it can therefore be advantageous if the glass element 1 is moved in the etching medium without rotation in one or more spatial directions or combinations thereof.

[0119] In particular, in combination of the movement of the glass element 1 with a movement of the etching medium 200, the height deviations 20, or an elevation or depression, can be formed symmetrically or asymmetrically. A symmetrical height deviation 20 can be achieved, for example, by rotating the glass element 1 about an axis that is arranged transversely, in particular perpendicular to the direction of movement of the etching medium 200. The glass element 1 can preferably be rotated about an axis that is oriented perpendicular to the first and / or second surface 2, 3. Another possibility for forming a symmetrical structure, or height deviations 20, is an up-and-down movement of the glass elements 1, preferably with a stationary etching medium 200. Preferably, the glass elements 1 are rotated about two axes, which are in particular perpendicular to one another, with a stationary or inhomogeneously moving etching medium 200 in order to produce a symmetrical height deviation 20.In general, it can therefore be provided that the glass element 1 is moved in the etching medium along a path with at least one reversal of direction.

[0120] An asymmetric structure, or height deviations 20, can be created, however, if preferably only the etching medium 200 and / or the glass-enriched etching medium 200 is in motion. In this case, the height deviations 20 are preferably formed in the direction of movement or sinking of the etching medium 200, since the glass-enriched etching medium 200 locally leads to a reduced removal rate.

[0121] A further control parameter is the orientation of the glass elements 1 in the etching medium. As shown in Fig. 7, the glass element 1 or several glass elements 1 can be aligned, preferably vertically, transversely, or perpendicularly with respect to the container bottom. It is therefore possible to align the glass elements 1 with respect to a direction of movement of the etching medium, in particular in order to control the formation and / or shape of at least one height deviation 20. In the right-hand holder 50, the glass elements 1 are aligned, for example, obliquely with respect to the container bottom and / or the direction of movement of the etching medium 200. This can preferably generate turbulence in the etching medium 200, for example at certain edges of the glass elements 1. In such a case, an accelerated removal rate can be achieved due to the rapid removal of the glass-enriched etching medium 200 due to the turbulence, in particular locally.In this case, a depression can be created with respect to the first and / or second surface 2, 3, preferably at least partially around the recess 10.

[0122] In a further embodiment, the glass elements 1 can be aligned substantially parallel to the container bottom or preferably horizontally. In this case, glass-enriched etching medium 200 can sink through the recesses 10 and, in particular, be evenly distributed around the recesses, so that a symmetrical height deviation 20, preferably an elevation, can be created on the surface 2, 3 opposite the container bottom. In contrast, on the surface 2, 3 facing away from the container bottom, at least no elevations 20 can be formed, or elevations 20 can be formed that have a lower height. Rather, due to the sinking and glass-enriched etching medium 200, depressions can be created, in particular at the edges of the surface 2, 3 facing away from the container bottom, due to the inflow of unsaturated etching medium and the resulting increased removal rate.

[0123] For example, if the first surface 2 faces the container bottom, a protrusion is created on the first surface 2 because saturated etching medium sinks out of the recess, thus reducing the removal rate. On the second surface 3 opposite the first surface 2, however, depressions are preferably created.

[0124] Fig. 8 shows the influence of temperature on the removal rate. Shown are measurement results of the height deviations 20 as a function of the temperature of the etching medium 200 and the orientation and shape of the recess 10. Therefore, the different shapes of the recess are plotted under the abscissa axis. The direction of movement of the etching medium 200 was aligned parallel to the first and second surfaces 2, 3. It is noticeable that the height deviations 20 are more pronounced for all shapes or structures of the recess 10 when the etching medium 200 has a temperature of, for example, 125°C, compared to an etching medium with a temperature of 80°C. Without being limited to the exemplary structures shown, the height, and preferably also a depth of the height deviations 20, in particular at least partially around the recess 10, can be significantly controlled by adjusting the temperature of the etching medium.

[0125] Since the removal rate increases at elevated temperature, more material is also dissolved. This leads to the etching medium 200 being saturated more quickly around an area with high removal, in particular the recess 10, and thus the removal rate in this area decreases rapidly. In general, the height and / or depth of the height deviations 20 scale with the removal or the removal rate. The higher the removal, the greater the height deviations 20. However, the removal rate in areas without a recess 10, e.g., in the area of ​​the first and second surfaces 2, 3, remains substantially higher than in the area around the recess. In other words, the removal rate can be set such that the removal rate is higher in one area of ​​the glass element 1 than in another area, e.g., at least partially around the recess 10.

[0126] In particular, depending on the set movement of the etching medium 200 and / or the holder 50, the height deviation 20, in particular around the recess 10, can be or become asymmetrically shaped. In a further embodiment, however, the height deviation 20 can also be or become symmetrically shaped, in particular around the recess 10. In this case, the recess 10 itself is also formed symmetrically with respect to an axis of rotation parallel to the longitudinal direction L. Symmetrical in the sense of the invention is understood such that the elevation, in particular around the recess, has a substantially uniform height or depth and / or a uniform shape, e.g., gradient. In this sense, asymmetrical therefore means that the height deviation 20, in particular around the recess 10, has different heights / depths and / or gradients at least in sections.

[0127] Another effect can also be seen in Fig. 8. Particularly with the elongated shape of the recess, the size of the height deviation depends on the orientation relative to the direction of movement. For example, with the elongated shape, when the etching bath flows over it transversely to the longitudinal direction (3rd measured value from the left), the height deviation is significantly smaller than when the flow is in the longitudinal direction (6th measured value from the left). This is attributed to the time required for the liquid of the etching medium to cross the recess. The time is significantly shorter for the 3rd measured value from the left than for the 6th measured value from the left. Therefore, according to one embodiment of the invention, a desired height deviation can generally be set by adjusting the duration for the etching medium to flow over the recess and / or by orienting the recess relative to the direction of movement or flow direction.

[0128] Fig. 9 shows a diagram illustrating the relationship between the depth of the height deviation 20, or the depth of the depression, as a function of the temperature of the etching medium 200, particularly during an up-and-down movement of the glass elements 1, with the surfaces of the glass elements oriented at an angle of 35° to the direction of the up-and-down movement. The inclined position of the discs forces the etching medium to flow over the surface, regardless of the current movement of the etching medium. The etching medium 200 was additionally set in motion by means of a magnetic stirrer.

[0129] Essentially, two effects are visible. Firstly, the height deviation 20 is of varying intensity on the first 2 and second 3 surfaces. Secondly, the height deviation 20 is more pronounced, particularly at higher temperatures of the etching medium 200 and / or a diagonal orientation of the glass element 1 with respect to the direction of movement of the etching medium 200, than at lower temperatures and, for example, a vertical orientation of the glass elements 1 at an angle of 0°. In this example, it is assumed that the first surface 2 defines the top side, i.e., the side of the glass element 1 facing away from the container bottom, wherein the second surface 3 can accordingly be the bottom side, i.e., the side of the glass element 1 facing the container bottom.

[0130] Furthermore, it is noticeable that the height deviation 20 is a depression in all cases, the depth of which preferably varies between approximately 65 nm and approximately 5 nm. It can therefore be deduced from the measurement data that at least the depth of the height deviation 20 can be significantly controlled by the temperature of the etching medium 200 and / or the orientation of the glass element 1 with respect to a direction of movement of the etching medium 200.

[0131] Fig. 9 thus illustrates that the removal rate on the second surface 3 facing the container bottom or the flow direction of the etching medium 200 is higher, in particular at high temperatures, e.g., 125°C, than at lower temperatures, e.g., 100°C, wherein the removal rate is also lower on the first surface 1 facing away from the container bottom or the flow direction of the etching medium 200. The height deviation 20 can therefore be more or less pronounced on the first surface 2 than on the second surface 3. Depending on the set process parameters, the glass element 1 can also be configured such that the first and second surfaces 2, 3 have a substantially uniform height deviation 20. In other words, the height deviations 20 of the first and second surfaces 2, 3 can be substantially symmetrical with respect to one another.The mirror plane is preferably located centrally between the first and second surfaces 2, 3 and in particular also parallel to these surfaces 2, 3. However, it is also conceivable to design the height deviations 20 asymmetrically with respect to this central plane.

[0132] Fig. 10 shows the topography corresponding to a height measurement on a glass element 1 after etching. The topography is shown at approximately 6 mm 2of the surface 2, 3 of the glass element 1 after it has been exposed to the etching medium. The different shades of gray represent different height deviations, and the area colored white 82 roughly represents the reference surface. In this example, the glass element 1 was aligned with the surface 2, 3 within the etching medium 200 roughly transversely to a container bottom, so that the recess 10 was aligned parallel to the container bottom. It can be seen that the height deviation 20 in the direction of 4 to 5 o'clock of an imaginary clock forms a depression 81, i.e. a recess, which is shown in dark gray. Furthermore, the height deviation 20 is essentially formed around the recess 10 as an elevation 80, which is shown in light gray. The height deviation 20 shown in Fig. 10 thus shows an essentially asymmetrical structure.

[0133] On the right-hand edge, a scale with the respective height values ​​(in nm) is shown, with the value 0 being the reference value. The topography is due to the fact that the etching medium 200 within the recess 10 became enriched with dissolved glass components, thereby increasing its density. The glass-enriched etching medium 200 then sank out of the recess, causing the etching medium 200 to move. This movement allowed further material to be dissolved as the heavy etching medium 200 sank, creating the depressions towards the container bottom (4-5 o'clock). On the other hand, this downward movement of the etching medium 200 also meant that less glass could be dissolved essentially radially around the recess 10, since the etching medium 200 was able to become enriched with glass there much more slowly and could therefore sink less quickly.The movement of the etching medium 200 was therefore slower radially around the recess 10 than within the recess 10, and residual material could settle around the recess 10, whereby height deviations 20 could form in the form of elevations.

[0134] Analogous to Fig. 10, another embodiment is shown in Fig. 11. The measurement data / topography of the substrate surface around the recess shown here was recorded pixel-by-pixel using a white light interferometer, and the evaluation results are displayed as a grayscale image. The line scan described below thus represents the best possible interpolation of the data grid along the selected evaluation path. A line YZ is also shown in the image. The height profile calculated and interpolated from the data along this line is shown in the graph below the image. This line YZ was placed across the recess 10. Based on the height profile, or topography, of the elevation 20, which is shown in the lower part of Fig. 11, a symmetrical characteristic of the height deviation 20 can be easily read off. The missing values ​​between approximately 400 pm and approximately 1900 gm represent the recess 10.It is clearly visible that the altitude deviation 20 in the rear area of ​​the line scan, especially in the section between 1900 pm and 2000 pm, is somewhat more pronounced, or has lower values, than in the front section from 0 pm to 400 pm.

[0135] In this example, the glass element 1 was structured, preferably using the method described above, such that the structure, or height deviation 20, is substantially symmetrical and / or formed as a depression. In the view shown, the height deviation 20 is arranged around the recess 10. In this example, the recess 10 is shaped such that its width decreases toward the lower edge of the image, preferably so that the recess 10 is shaped as a point. The depth of the height deviation 20 increases toward the recess 10, which can be seen in the dark tones, as well as in the illustrated height profile of the line scan YZ. However, the image section shown is small, so that the line scan only partially captures the height deviation 20, in particular the topography of the glass element 1. Based on this height profile in the lower area of ​​Fig. 11, it can be seen that the height deviation 20 is a depression. List of Reference Symbols

Claims

Patent claims:

1. A plate-shaped glass element (1) with a first surface (2) and a second surface (3) arranged opposite the first (2), and at least one recess (10) that penetrates at least one of the surfaces (2, 3), wherein the recess (10) extends in a longitudinal direction (L) and a transverse direction (Q) and the longitudinal direction (L) of the recess (10) is arranged transversely to the surface (2, 3) that is penetrated by the recess (10), characterized in that the surface (2, 3) that is penetrated by the recess (10) has at least one of the following features: the surface (2, 3) has at least partially around the recess (10) at least a height deviation (20) relative to the surface (2, 3), wherein the amount |Ah| the height deviation (20), in particular with respect to a depth or a height, is greater than 0.005 pm, preferably greater than 0.05 and / or less than 0.1 pm, preferably less than 0.3 pm,preferably smaller than 0.5 pm, the surface (2, 3) which is penetrated by the recess (10) has a mean roughness (Ra) which is less than 15 nm, an edge (40) between the surface (2, 3) and the recess (10) is formed without protrusions.

2. Plate-shaped glass element (1) according to claim 1, characterized in that the height deviation (20) has at least one of the following features: the height deviation (20) completely encloses the recess (10), the height deviation (20) is designed as a shortening of the wall (11) of the recess (10), the height deviation (20) forms a depression or a protrusion, A surface (22) of the height deviation (20) is at an obtuse angle to the first surface (2) which is penetrated by the recess(s) (10), the height deviation has lateral dimensions that are greater than 5 pm, preferably greater than 8 pm, preferably greater than 10 pm and / or less than 5 mm, preferably less than 3 mm, preferably less than 1 mm.

3. Plate-shaped glass element (1) according to one of the preceding claims, characterized in that the glass element (1) has a thickness (D) greater than 10 pm, preferably greater than 15 pm, preferably greater than 20 pm and / or less than 4 mm, preferably less than 2 mm, preferably less than 1 mm.

4. Plate-shaped glass element (1) according to one of the preceding claims, characterized by at least one of the following features: the recess (10) is designed as a channel (15) which extends through the glass element (1) from the first surface (2) to the second surface (3) and penetrates both surfaces (2, 3), a wall (11) of the recess (10) has a plurality of dome-shaped depressions.

5. Plate-shaped glass element (1) according to one of the preceding claims, characterized in that an edge (40) is formed by a plurality of openings (15) extending through the glass element (1) from the first surface (2) to the second surface (3) and directly adjacent to one another, which forms an outer edge of the glass element (1) at least partially surrounding the glass element (1), or an inner edge of the glass element (1) at least partially surrounding the recess (10), wherein the edge (40) has a plurality of dome-shaped depressions.

6. Plate-shaped glass element (1) according to one of the preceding claims, characterized by one of the following features: The height deviation (20) is symmetrically shaped, the height deviation (20) is asymmetrically shaped.

7. Plate-shaped glass element (1) according to one of the preceding claims, characterized by one of the following features: - An inner edge of the glass element (1) has a multitude of dome-shaped depressions and the first (2) and second (3) surfaces of the glass element (1) are designed without domes, - An inner edge of the glass element (1) has a higher mean roughness value (Ra) than the first (2) and second (3) surfaces of the glass element (1).

8. Method for modifying a surface (2, 3) of a plate-shaped glass element (1) with a first surface (2) and a second surface (3) arranged opposite the first (2), and at least one recess (10) that penetrates at least one of the surfaces (2, 3), wherein the recess (10) extends in a longitudinal direction (L) and a transverse direction (Q) and the longitudinal direction (L) of the recess (10) is arranged transversely to the surface (2, 3) that is penetrated by the recess (10), wherein in the method: - the glass element (1) is provided, - at least one filament-shaped channel (15) is generated in the glass element (1) by a laser beam (100) of an ultrashort pulse laser (101), wherein its longitudinal direction (L) runs transversely to the surface of the glass element (1), - the surface (2, 3) of the glass element (1), which is penetrated by the channel, is exposed to an etching medium (200) which removes glass from the glass element (1) at an adjustable removal rate, whereby the channel is widened by the etching medium so that a recess (10) is formed, - wherein at least one of the following features of the surface (2, 3) which is penetrated by the recess (10) is produced by etching: o the surface (2, 3) has at least partially around the recess (10) at least a height deviation (20) relative to the surface (2, 3), wherein the magnitude |Ah| of the height deviation (20), in particular with respect to a depth or a height, is greater than 0.005 gm, preferably greater than 0.05 gm and / or less than 0.1 gm, preferably less than 0.3 gm, preferably less than 0.5 gm, o the surface (2, 3) which is penetrated by the recess (10) has a mean roughness value (Ra) which is less than 15 nm, o an edge (40) between the surface (2, 3) and the recess (10) is formed without protrusions.

9. Method according to the preceding claim, characterized in that the etching medium (200) is set in motion such that the removal rate is accelerated or reduced by the movement of the etching medium (200).

10. Method according to the preceding claim, characterized by one of the following features: the glass element (1) is moved in the etching bath without rotation in one or more spatial directions or combinations thereof; the glass element (1) moves along a path with at least one change of direction; the glass element (1) is rotated about an axis which is arranged transversely, in particular perpendicularly to the direction of movement of the etching medium (200); the glass element (1) is rotated about an axis which is oriented perpendicular to the first and / or second surface (2, 3).

11. Method according to one of the preceding claims, characterized in that the etching medium (200) is modified in at least one defined area on the surface (2, 3) of the glass element (1) and the removal rate in this area is changed compared to surrounding areas.

12. Method according to one of the preceding claims, characterized in that the removal rate is adjusted by generating a spatial and / or temporal temperature gradient.

13. Method according to one of the preceding claims, characterized in that the removal rate is set by a spatial arrangement of the glass element within the etching medium (200), in particular with respect to gravity and / or a direction of movement of the etching medium (200).

14. Method according to one of the preceding claims, characterized in that the removal rate is adjusted by selecting a combination of glass composition and composition of the etching medium (200).

15. Application of the glass element (1) according to one of the preceding claims for the manufacture of components for the hermetic packaging of electro-optical functionalities, microfluidic cells, pressure sensors and / or camera imaging modules.

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