Glass wafers and glass elements for pressure sensors

Abstract

The present invention generally relates to glass wafers for producing glass elements for use in pressure sensors, glass elements for use in pressure sensors, and methods for producing such glass elements and glass wafers. A further aspect relates to pressure sensors comprising or obtainable by such glass elements.

Description

[Technical Field]

[0001] The present invention relates, in general, to glass wafers for manufacturing glass elements used in pressure sensors, such as piezoresistive or capacitive pressure sensors, preferably piezoresistive pressure sensors; glass elements for use in pressure sensors; and methods for manufacturing such glass elements and glass wafers. Further embodiments relate to pressure sensors comprising, or obtainable by, such glass elements.

[0002] Background of the Invention Microelectromechanical (i.e., MEMS) pressure sensors feature a thin silicon diaphragm that is elastically deformable under pressure. This silicon diaphragm is typically mounted on a base made of an insulator or semiconductor material such as silicon. The base has an opening through which a fluid, such as a gas or liquid, can enter the pressure sensor's measuring cavity. Here, pressure is applied to the diaphragm from both sides; a reference pressure is applied to one side, and a variable pressure is applied to the side of the diaphragm facing the measuring cavity. The reference pressure can be fixed or variable. When the pressures on the two sides of the diaphragm differ, the diaphragm deforms. The diaphragm incorporates a measuring resistor (a so-called piezoresistor) whose resistance changes when it deforms. These are electrically arranged in the form of a so-called Wheatstone bridge circuit. When the diaphragm deforms, the voltage across the bridge circuit changes. This measurable change in bridge voltage is approximately proportional to the pressure difference.

[0003] Furthermore, it is also possible to measure the pressure difference capacitively. In this case, the silicon does not have a built-in resistor, but rather a micromechanical structure for measuring capacitance, i.e., a capacitor function, is incorporated.

[0004] For the base material of such pressure sensors, insulating materials such as glass or semiconductor materials such as silicon can be used. To miniaturize the components, thin base elements with a thickness of less than 1 mm are used, if possible, for example, in the range of 200 μm to 900 μm, especially 800 μm or 400 μm. However, thicker bases may be required to optimize the thermal coupling between the MEMS component and the support material. These can be up to 3.5 mm thick.

[0005] The detailed configuration of the openings provided in the base material is variable. Generally, these openings have a circular cross-section, but the size of the opening can vary depending on the thickness of the base material. For example, the opening can have a frustoconical shape, meaning that the walls of the opening are inclined relative to each other in a circular cross-section. Openings with a frustopyramidal shape are also known.

[0006] Japanese Patent Publication No. 57-128074 describes a pressure sensor in which a base material is formed from a silicon single crystal of a specific crystal orientation. The opening in the base is obtained by anisotropic etching of the single crystal. By precisely oriented the single crystal base material, it is possible to obtain openings of various geometric shapes, and in addition to openings with a circular cross-section, openings with a rectangular cross-section are also possible.

[0007] U.S. Patent Application Publication No. 2011 / 0000304 describes a pressure sensor with a glass base, wherein the openings of the glass base have different diameters such that the diameter of the opening facing the silicon diaphragm is larger than the diameter of the opening facing the metal base. No method for producing different diameters in the glass material is described.

[0008] U.S. Patent Application Publication No. 2006 / 0288793 describes a pressure sensor including a pressure-transmitting gel, wherein there is a predetermined ratio between the thickness of the glass base surrounding the pressure sensor and an opening provided in the glass base. This ensures a sufficient diameter for the opening while keeping the thickness of the glass base very small, thereby preventing deformation of the silicon diaphragm by the gel, which can occur particularly due to the expansion of the gel caused by temperature changes.

[0009] U.S. Patent Application Publication No. 2995 / 0172724 describes a pressure sensor with a glass base. The glass base has openings of varying sizes depending on the thickness of the glass base. For example, the openings can be frustum-cone or frustum-pyramidal in shape. Here, the opening on the side of the glass base opposite the pressure sensor diaphragm is smaller than the opening on the side of the glass base facing the silicon diaphragm. This is to prevent, or at least minimize, the ingress of impurities into the measuring cavity that would reduce the accuracy of the pressure measurement. The openings can be provided in the glass base by, for example, USSL (ultrasonic vibration lapping).

[0010] Japanese Patent Publication No. 09-126924 also describes that the size of the opening in the glass base differs depending on the thickness of the glass base. In this case, the opening is formed by an etching process. The size of the opening is larger on the side of the glass base opposite the silicon diaphragm than on the side of the glass base facing the silicon diaphragm. This improves the mechanical stability of the opening in the glass base and prevents the edge of the opening on the side of the glass base opposite the silicon diaphragm from cracking.

[0011] U.S. Patent No. 9470593 describes a pressure sensor in which the cover or cap may be made of glass and has an opening, the opening may be of any shape and size, so that a fluid can reach a wafer through the opening.

[0012] Furthermore, U.S. Patent Application Publication No. 2009 / 0096040 describes sensors having an optimized sensor shape.

[0013] Thus, pedestals for pressure sensor applications are known from the prior art in a very diverse configuration. In this case, it has been found that the exact configuration of the opening of the pedestal has a great influence on the mechanical stability and / or reliability of the pressure sensor. For example, the size of the opening, the inclination angle of the side walls or sides, and furthermore the configuration of the surface of these side walls or sides play an important role, for example, with regard to wettability and / or coating properties. Here, the targeted adjustment of the surface properties of the side or side walls of the glass pedestal, for example, preferably in a highly reproducible process, preferably in combination with the geometric configuration of the opening in the wafer or sheet surface, for example, in such a form that at least one edge of the opening is at least partially formed linearly, can make a decisive contribution to the improvement of known pressure sensors.

[0014] Therefore, there is a need for a glass element for a pressure sensor or a glass wafer for its manufacture that at least mitigates the known drawbacks of the prior art.

[0015] Problem of the Invention Therefore, an object of the present invention is to provide a glass wafer or a glass element for use in a pressure sensor that further improves the mechanical stability and / or reliability of the pressure sensor. A further aspect is a method for manufacturing the glass element and a pressure sensor provided with the glass element.

[0016] The improvement of the stability and / or reliability of the pressure sensor here may be, for example, an improvement in mechanical stability, and thus, for example, an improvement in the life of the pressure sensor, but generally also includes other aspects, for example, the uniformity and / or stability of the signal generated by the sensor.

[0017] Summary of the Invention The object of the present invention is solved by the subject matter of the independent claims. Preferred specific embodiments are obtained from the dependent claims and the further disclosure of this specification.

[0018] Thus, the present disclosure is a glass wafer for manufacturing a frame-shaped glass element for use in a pressure sensor, for example a piezoresistive or capacitive pressure sensor, preferably a piezoresistive pressure sensor, the glass wafer comprising a plate-shaped glass substrate and at least one opening extending from one surface of the plate-shaped glass substrate to the other surface of the plate-shaped glass substrate, the opening having a cross-section with a cross-sectional area, the cross-sectional area being defined by at least one straight portion, the straight portion preferably having a minimum length of at least 10 μm, preferably at least 20 μm, particularly preferably at least 100 μm, the opening having side surfaces, the side surfaces having surfaces, the surfaces preferably having a skewness Ssk determined by the following formula

Number

[0019] In the above formula, S q represents the root mean square roughness of the surface, i.e. the RMS value. A represents the area of the integration region for determining the skewness. Z(x,y) represents the respective height value of the surface profile at coordinates x,y. This height value is shown based on the arithmetic mean value of the height values of the surface profile. Thus, if a point on the surface profile is higher than the average value, the corresponding value Z(x,y) is positive, and if that point is lower than the average value, Z(x,y) is negative. In an actual surface measurement, instead of calculating the integral, the surface profile at discrete points can be determined. The integral can be replaced by a sum, and the area can be replaced by the number of the sum, i.e. the number of measurement points. Then, Ssk becomes as follows:

Number

[0020] Distortion is advantageously measured by white light interferometry (WLi). Such measurements can be performed with a white light interferometer, such as the ZYGO NewView, from Zygo. The data is collected using the ZYGO Mx software at appropriate magnification (20x magnification and 0.5x zoom with the objective lens). TN It is recorded and evaluated. To improve the accuracy of the evaluation, the software can be used to limit the evaluation area (so-called mask) and eliminate areas that cannot be measured. Here, a rectangular measurement area with dimensions of 740 μm × 320 μm or 740 μm × 520 μm can be selected as needed. In this case, the value of Ssk is determined according to the following formula or formula (1) above:

number

[0021] Value S q It can be calculated using the following formula:

number

[0022] Therefore, this is the mean square of the height. Also, when determining this, it is possible to calculate it using a discrete number of measurement points by summing instead of integration:

number

[0023] Preferably, the skewness value is at least 0.002, more preferably at least 0.003, particularly preferably at least 0.004, and very particularly preferably at least 0.01.

[0024] According to one preferred embodiment, the skewness value is at most 2.0, and particularly preferably at most 1.5.

[0025] In particular, the skewness value may be 0.003 to 5, preferably 0.004 to 2.0, and especially preferably 0.01 to 1.5.

[0026] In particular, according to one embodiment, the degree of strain can be made greater than 0. In this case, the surface is formed as a surface mainly characterized by elevated areas. A surface with adjacent raised areas can be advantageous for fluid passage because a turbulent boundary layer is formed on the wall surface of the holes by the notch configuration. This acts to locally increase the viscosity of the fluid and promotes laminar flow in adjacent areas.

[0027] In this case, the skewness is advantageously at least 0.001 and advantageously at most 5. Here, preferably, the skewness is at least 0.002, particularly at least 0.003, advantageously at least 0.004, and very particularly preferably at least 0.01. Even more preferably, the skewness is at most 2.0, and preferably at most 1.5.

[0028] Here, the preferred range of skewness is at least 0.003 and up to 5, particularly at least 0.004 and up to 2.0, and especially preferably 0.01 to 1.5.

[0029] In a further embodiment, the strain can be less than zero. In this case, the surface is primarily characterized by lows. In this case, the surface does not have narrow lows, which are sometimes called notches. As a result, the notch effect is reduced, especially when a load is applied under pressure, and the strength of the part is improved.

[0030] In this case, the skewness is advantageously at most -0.001, and more advantageously at least -5. Preferably, the skewness is advantageously at most -0.002, particularly at most -0.003, advantageously at most -0.004, and very particularly preferably at most -0.01. More preferably, the skewness is at least -2, and preferably at least -1.5.

[0031] Here, the preferred range of skewness is from a maximum of -0.003 to at least -5, particularly from a maximum of -0.004 to at least -2.0, and especially preferably from -0.01 to -1.5.

[0032] In this disclosure, the following definitions apply:

[0033] In this disclosure, "glass substrate" means a product consisting of or containing a glassy material. "Glassy material" generally means an inorganic amorphous material that is melted from a mixture in a melting process. A so-called hot forming process may be carried out after the melting process to obtain, for example, a panel or plate consisting of or containing a glassy material (i.e., a glass panel or plate glass). Hot forming processes known to those skilled in the art include, for example, stretching, rolling, or floating. Therefore, a glass substrate in the spirit of this disclosure may be formed, for example, as plate glass or a glass panel. In particular, in this disclosure, the glassy material may be, or contain, so-called borosilicate glass.

[0034] Here, a flat area of ​​a surface or plane in general means a non-curved area of ​​the surface or plane in general. However, a flat area may have a particularly rough configuration. In other words, a flat area in the intent of this disclosure does not mean an ideally flat or smooth area. In particular, a flat area in the intent of this disclosure may be an area defined by at least one straight portion.

[0035] The glass substrate is advantageously formed to be transparent, where transparency refers to electromagnetic radiation in the wavelength range of 380 nm to 780 nm, i.e., the visible light range.

[0036] The glass substrate may be formed in a plate-like shape. This means that the transverse dimension of the glass substrate in a first direction of the Cartesian coordinate system (which may also mean the thickness of the glass element) is at most one-fifth of the transverse dimensions in two further directions of the Cartesian coordinate system perpendicular to the first direction (which may also mean the length and width of the glass element). In other words, the thickness of the glass substrate is at most one-fifth of its length and width. Embodiments are also possible in which the length and width of the glass substrate clearly exceed five times its thickness. In this case, the glass substrate is formed as a very long and wide sheet, for example, as a sheet of glass or a sheet of glass ribbon. In this specification, a ribbon is a molded body whose length is clearly greater than its width, for example, an order of magnitude larger. If the length and width are of the same order, it is usually called a plate. If the glass substrate is formed in a circular shape, the length and width are replaced by the diameter of the glass substrate.

[0037] Here, the horizontal dimension refers to the distance between the surfaces that define the glass substrate. In other words, a glass substrate is a molded body made of or containing a glass-like material. In this disclosure, when referring to the surface of a glass substrate, and by extension the surface of a glass wafer or glass element, unless explicitly stated otherwise, it refers to the surface that accounts for more than 50% of the total surface area of ​​the molded body. If the glass substrate has a plate-like configuration, these surfaces may also be called principal surfaces, which are defined by the length and width of the glass substrate, or two circular or two elliptical surfaces if the glass element has a circular or elliptical configuration. The principal surfaces of a glass substrate may also be called faces. Depending on the detailed arrangement of the glass substrate, and by extension the glass wafer or glass element, these may also be called the top and bottom surfaces if the glass substrate (or wafer or glass element) is arranged horizontally, or the front and back surfaces if it is arranged vertically.

[0038] Typically, the surfaces of a glass substrate are arranged substantially parallel to each other; that is, from a geometric standpoint, the glass substrate can be described as a thin, sometimes elongated cuboid, or a thin cylinder, or generally a thin prismatic body with any base surface. Substantially parallel arrangement of surfaces means that the surfaces are at an angle of up to 5° to each other, and are advantageously arranged parallel to each other within normal manufacturing tolerances.

[0039] A glass wafer (or glass element wafer) means a molded body comprising a glass substrate and at least one opening. That is, a glass substrate can mean a glass plate without openings, and a glass wafer can mean a glass plate with multiple openings. In the intent of this disclosure, a glass element generally has only one opening, is smaller than a glass wafer, and in particular can be obtained by fragmenting a glass wafer. When a glass element or the surface of a glass wafer is referred to herein, it is obvious that these are the surfaces of the glass substrate contained in the glass wafer. The thickness of the glass substrate, the thickness of the glass wafer containing the glass substrate, and the thickness of the glass element obtained by fragmenting from the glass wafer are similarly relevant. Similarly, the same applies to the chemical composition of the glassy material of the glass substrate, glass element, and glass wafer.

[0040] In this disclosure, an opening extending from one surface of a glass element (or glass wafer) to the other surface of the glass element (or glass wafer) means a continuous recess in the glass element, glass wafer, or glass substrate. That is, no glassy material is present in the region of the opening. Therefore, the opening may also be called a channel or hole. Thus, a glass element having such an opening is formed in a frame-like manner, that is, the opening is covered or surrounded by glassy material. In this specification, a frame-like glass element also means that the frame-like glass element has exactly one opening.

[0041] Geometrically, an opening can be described as a hollow body having one or possibly two base areas corresponding to the cross-section of the opening on each face of the glass element or glass wafer, and a height corresponding to the thickness of the glass element / glass wafer. The base area of ​​the opening is also called the cross-sectional area. If the two base areas are of the same size, it can be said that the opening has one cross-sectional area. Here, when referring to the size of the cross-sectional area, if the size of the cross-sectional area of ​​the opening changes in the height direction, the average value of the cross-sectional area can be generally indicated. In general, an opening can be described as a hollow body in the form of a prism or cone, and if the size of the cross-sectional area changes in the height direction of the opening, it can be described as a truncated pyramid, and if the size of the cross-sectional area increases continuously in the direction of one surface of the glass element, it can be described as a truncated cone. Furthermore, it is theoretically possible for the cross-sectional shape to change. However, from a process technology or manufacturing technology standpoint, it is preferable that the cross-sectional shape remains unchanged and only the size changes.

[0042] The opening is further defined by the sides formed by the glassy material of the glass element / glass substrate, i.e., the walls of the opening. These sides correspond to the sides of a prism when the opening is configured as a prism, and, depending on the detailed configuration, to the sides of a truncated pyramid, a cone, or a truncated cone. More complex geometric configurations of the sides are conceivable but are undesirable for process or manufacturing reasons.

[0043] In general, the cross-sectional area can have any shape in principle, and for example, a circular cross-sectional area is also possible in principle. However, it is advantageous in this disclosure that the cross-sectional area is formed in a manner in which the cross-sectional area is defined by a straight portion, and the straight portion has a minimum length of at least 10 μm, preferably at least 20 μm, or even more preferably at least 100 μm. Such a configuration can be particularly advantageous when using a glass element in a pressure sensor, because by doing so, that is, particularly advantageously, the shape of the diaphragm can be as narrow as possible. teeth, The opening below it In accordance with formation So This is because it has been found that by doing so, pressure peaks are avoided in the measurement cavity of the pressure sensor, resulting in a more uniform load on the silicon diaphragm, particularly over time. In other words, such a cross-sectional area configuration can at least reduce pressure fluctuations over time. This can advantageously extend the lifespan of a pressure sensor with such a glass element, based on the lower mechanical load on the silicon diaphragm. Therefore, in principle, using non-circular cross-sectional elements in the design of the opening can advantageously construct the vibration modes of the diaphragm, i.e., control the location and intensity of the vibrations. Here, even very short linear sections can make a contribution. The minimum length of the linear section is at least 10 μm, preferably at least 20 μm. In the best case, a length of at least 100 μm is possible, in which case the length is preferably up to 2 mm, particularly preferably up to 1.7 mm.

[0044] In particular, openings with non-circular cross-sectional areas, such as rectangular cross-sectional areas, have been found to be advantageous, especially when using glass wafers or glass elements as pressure sensors. Typically, the measuring cavities within the silicon diaphragms of such pressure sensors, such as capacitive or piezoresistive types, are also formed, usually rectangular, often square. Here, the cross-section of the measuring cavity is larger than the opening of the glass element. Therefore, it has been found that rectangular openings, especially those with a cross-section similar to that of the cavity, i.e., with a corresponding shape, result in lower surface loads when pressure is applied. This is advantageous because it reduces the load on the interface between the silicon diaphragm and the glass element, making delamination less likely. In other words, such pressure sensors have higher stability against burst pressure, allowing them to be used at higher pressures.

[0045] Here, we will demonstrate the following relationship through calculation: - The larger the free region created in the glass element below the silicon diaphragm, that is, the more glass regions not bonded to the silicon diaphragm exist within the measurement cavity, the smaller the difference between an opening with a circular cross-section and an opening with a non-circular cross-section, i.e., an opening with a cross-sectional region having at least one straight portion. Conversely, this means that the configuration of the straight portions or angular portions of the cross-sectional region becomes particularly important, especially when the resulting free region is small.

[0046] - The larger the resulting free region, the higher the surface load generated when pressure is applied, and consequently, the greater the applied force.

[0047] - The greater the pressure applied to the sensor, the smaller the resulting free region should be. This is because it further reduces the load on the bonding interface.

[0048] In general, changing the cross-sectional shape from circular to square—that is, changing from a circular cross-sectional region with diameter x to a cross-sectional region that is at least nearly square with a side length x corresponding to the diameter x of the circular cross-sectional region—reduces the resulting free region by approximately 27%. In particular, a smaller resulting free region clearly affects the applied force.

[0049] This is particularly important in pressure sensors designed for high-pressure applications, i.e., pressures of at least 30 bar.

[0050] The resulting free region (or region) mentioned above is created by the difference between one or more lateral dimensions of the cavity and the dimensions of the opening of the glass element.

[0051] This is shown in the table below with a calculation example. Here, the calculation was performed using a square cavity with a side length of 1.18 mm as an example.

[0052] [Table 1]

[0053] In other words, for this square cavity, if the cross-sectional area of ​​the opening of the glass element is also square, the force acting on it is 14% less than when the cross-sectional area is circular. This advantageous property is particularly pronounced when the resulting free region is small, and especially when the ratio of the cavity's cross-sectional area to the opening's cross-sectional area is small, i.e., less than 10 or less than 5.

[0054] In this regard, the table above calculates the area ratio of the corresponding cavity / opening φ (for circular openings) or the area ratio of the cavity / opening □ (for rectangular, and in this case, square openings). If the resulting area ratio is small, as mentioned above, a difference of two orders of magnitude in the applied force occurs in the case of non-circular openings.

[0055] This tendency weakens as the area ratio increases.

[0056] This can be confirmed by the data listed in the table below: [Table 2]

[0057] In the example above, the advantage of the rectangular cross-section over the circular cross-section is no longer very significant, and the resulting free area is approximately 6 mm in each case. 2 When the overall magnitude is large, the difference in the force exerted will be very slight.

[0058] In other words, when the cross-sectional area is changed from a circular shape to a non-circular shape, a particularly good effect is observed when the ratio of the cavity's cross-sectional area to the opening's cross-sectional area is small, i.e., advantageously less than 10, and especially less than 5. Furthermore, this effect is particularly pronounced in the first of the two tables above, where the ratio of the cross-sectional areas of the cavity and the opening to each other is less than 3.

[0059] Preferably the shape of the diaphragm as much as possible. but, The opening below it In accordance with formation So In this disclosure, the shape of the diaphragm corresponds to the shape of the opening in such a way that the aspect ratio of the diaphragm is substantially equal to the aspect ratio of the opening. Here, substantially equal aspect ratios mean that the size of the cross-sectional area of ​​the diaphragm and the size of the cross-sectional area of ​​the opening may differ from each other, and / or the radius of the corners of the diaphragm and the radius of the corners of the opening may differ arbitrarily. However, according to this embodiment, apart from these differences, the shape of the cross-sectional area of ​​the opening corresponds to the shape of the diaphragm. According to one embodiment of a glass wafer, the shape of the diaphragm, for example, a silicon diaphragm teeth, The opening below it In accordance with Because it is formed in such a way that the aspect ratio of the diaphragm, particularly a silicon diaphragm, is equal to the aspect ratio of the opening, the shape of the diaphragm, for example, a silicon diaphragm, corresponds to the shape of the opening.

[0060] It can be particularly advantageous if the cross-sectional area is defined by two or more straight sections, for example, four straight sections. In particular, the cross-sectional area may be polygonal. Advantageously, the cross-sectional area is rectangular or square. This allows for a particularly uniform pressure distribution within the measuring cavity of a pressure sensor equipped with such a glass element. The polygonal configuration of the cross-sectional area, for example, rectangular or square, also means, in this specification, that the corners of such a polygon are rounded or at least can be rounded.

[0061] Furthermore, if the side surface is advantageous, then the following formula

number

[0062] Distortion is preferably determined in the flat region of the side, advantageously in the region corresponding to the straight portion. In this case, the region corresponding to the straight portion may be the same as or partially the same as the flat region of the side. Depending on the detailed configuration of the opening, for example, the region corresponding to the straight portion can also be interpreted as a sub-region of the flat region of the side. If the configuration of the opening is such that the cross-sectional shape is rectangular, for example, a rectangle with rounded corners, then the flat region of the side is formed by four rectangles, which can also be interpreted as the side of a prism. Distortion is determined here in particular in one of these side rectangles, and each of these rectangles may belong to the straight portion of the cross-sectional region of the opening.

[0063] In other words, according to the present disclosure, it is advantageous to manufacture glass elements having an asymmetric or non-uniform distribution of high or low points on the surface of the opening or in a region of the surface of the opening. This can be particularly advantageous when a frame-shaped glass element manufactured from a glass wafer according to embodiments of the present disclosure is used in a pressure sensor. This is because the asymmetric or non-uniform distribution of high or, optionally, low points can generate and intentionally influence the distribution of turbulent and laminar components of a fluid, such as a liquid or gas, toward a functional silicon MEMS diaphragm.

[0064] In this way, by giving the surface a predetermined configuration in at least one region, the flow resistance of the opening can be increased or decreased.

[0065] Structures aligned with the direction of flow, like shark skin in biological terms, can significantly reduce flow resistance. Such surfaces can improve the dynamic responsiveness of sensors.

[0066] Structures perpendicular to the flow direction or irregular structures increase flow resistance. When an external pressure shock is applied to the sensor, on surfaces with such configurations, the fluid can only flow slowly into the sensor (or measurement) cavity, resulting in a lower sudden load on the sensor diaphragm compared to an unstructured surface.

[0067] A similar effect occurs when the pressure on the sensor drops sharply; on a surface structured perpendicular to the flow direction, the medium escapes slowly from the cavity, resulting in a lower dynamic load on the sensor compared to an unstructured surface.

[0068] By combining these two effects, the damping of the cavity-sensor diaphragm in a vibrating system can be precisely adjusted, thereby allowing for targeted shifting of the system's natural vibrations, extending sensor lifespan, and achieving particularly high signal quality in specific frequency ranges.

[0069] Furthermore, it is possible to make the wall structure asymmetrical, which means that the resistance to flow in one direction is high, while the resistance to flow in the other direction is significantly low.

[0070] In addition to the movement of fluid into the cavity due to the diaphragm's motion, wave phenomena due to the compressibility of the medium cannot be ignored.

[0071] In the case of an impact load, compression or expansion waves flow from the opening towards the sensor diaphragm. Because these are reflected within the cavity, a high-frequency load is placed on the sensor diaphragm, and its amplitude is on the same order of magnitude as the pressure peak itself.

[0072] Here, by structuring the surface of the opening as intended, the waves are diffusely reflected within the opening, similar to diffuse reflectors in acoustic studios or concert halls, which has the advantage of making the pressure rise in the sensor diaphragm itself more gradual.

[0073] Here, it is advantageous that there is a minimum skewness, and therefore, the surface of the side in at least one region has the desired non-uniform distribution between high and low points. However, it can also be advantageous if the distribution is not so skewed, as this may lead to the dominance of undesirable flow components.

[0074] The shape of the surface morphology of the side walls or sides of the opening can be precisely controlled by process parameters during the manufacturing of the opening.

[0075] According to one embodiment, the surface is formed in a manner in which lows ("valleys") are dominant. In this case, the skewness is less than 0. According to another embodiment, highs ("peaks") may be dominant, in which case this corresponds to Ssk being greater than 0.

[0076] In the above formula, S q This represents the root mean square of the height, and is calculated using the following formula:

number

[0077] A represents the area of ​​the measurement region, x and y represent the surface coordinates of the region (measurement region), and z represents the height. The skewness (or strain) Ssk indicates the degree to which the distribution of surface heights is symmetrical around the average height. Therefore, it can be understood as an indicator of whether "valleys" or lows or highs are dominant in the surface topography. If highs and lows are equally distributed, the skewness takes a value of 0. For surfaces where lows are dominant, Ssk takes a negative value. If highs are dominant, Ssk is positive, i.e., has a value greater than 0. Favorably, the skewness is 0.1 mm 2 To exceed and be advantageous, 3mm 2 It is determined within a measurement range of less than [amount missing].

[0078] This invention relates to the inner surface topology of the side surface of an opening, preferably this particular topology is located in at least one region of the side surface, advantageously a region belonging to at least one straight portion of the cross-sectional region resulting from a structuring process. The structuring methods are diverse, and the parameters used therein are also diverse. Depending on the application, the inner surface needs to exhibit various properties.

[0079] Preferably, the surface of the side of the opening is provided, characterized mainly by lower points, sometimes by higher points, and especially by dome-shaped, i.e., hemispherical lower or higher points. Surprisingly, such adjustment of the surface has been found to improve the mechanical stability of the glass element. This is thought to be because a particularly favorable bonding state can be obtained on the surface within or on the side of the opening according to the present disclosure, and this bonding state can be obtained, for example, by substantial chemical removal of the surface. In other words, this means that particularly weak bonds of the glass network structure that are chemically attackable are broken, while strong bonds are initially still retained, and thus good overall mechanical stability of the glass element is obtained, which is characteristic of the side surface. In particular, in this way, the occurrence of conchoidal fractures at the opening can be reduced to some extent.

[0080] The shape of the dome-shaped inner wall structure can be precisely adjusted by process parameters. When a frame-shaped glass element is used as an example in a pressure sensor, the asymmetric / non-uniform distribution of peaks and valleys has been found to have fluid technology advantages, for example, in the distribution of turbulent and laminar flow components of liquids and gases directed toward a functional Si-MEMS diaphragm. As described above, customizing the inner wall structure of the opening may also enhance the signal in specific frequency ranges. Furthermore, it may be possible to suppress certain frequency ranges at least, thereby reducing the resulting signal noise.

[0081] According to one embodiment, the cross-sectional region is defined by at least two straight portions, the straight portions forming corners with a radius of curvature of at least 10 μm, preferably at least 20 μm, particularly preferably at least 50 μm, and advantageously up to 1000 μm, preferably up to 500 μm, particularly preferably up to 250 μm, more preferably up to 150 μm, very particularly preferably up to 130 μm, and most preferably up to 100 μm. This is advantageous because it can suppress pressure peaks at the corners of the cross-sectional region of the glass element thus incorporated into the pressure sensor.

[0082] In a further embodiment, the glass substrate comprises glass having at least 50% by weight of SiO2, preferably at least 55% by weight of SiO2, particularly preferably at least 70% by weight of SiO2, and very particularly preferably at least 78% by weight of SiO2, wherein the SiO2 content of the glass is advantageously limited to a maximum of 85% by weight of SiO2, preferably a maximum of 83% by weight of SiO2. That is, the glass is advantageously formed as high-purity SiO2 glass. This is advantageous because it provides glass that can be etched particularly efficiently using, for example, potassium hydroxide. Thus, an advantageous surface structure on the side of an opening can be manufactured particularly easily in such glass or glass element or glass wafer or glass substrate. However, it is desirable that the SiO2 content of the glass not be too high, as too high a content reduces the meltability of the glass. Therefore, advantageously, the SiO2 content of the glass is limited, and according to one embodiment, it is advantageously limited to a maximum of 85% by weight, preferably even more preferably a maximum of 83% by weight. By adjusting the SiO2 content to within the aforementioned limits, the etching process can be carried out efficiently on the glass substrate, while the glass substrate can be manufactured using an economical manufacturing process.

[0083] According to further embodiments, the glass substrate (or, in corresponding embodiments, the glass element or glass wafer) comprises glass having at least 1.5% by weight of B2O3, preferably at least 2.0% by weight of B2O3, particularly preferably at least 2.5% by weight of B2O3, and very preferably at least 5% by weight of B2O3, wherein the B2O3 content of the glass is advantageously limited to a maximum of 15% by weight. B2O3 is a glass component that generally improves the chemical resistance of glass. In addition, the inclusion of a certain amount of B2O3 lowers the melting point of the glass and improves its meltability. This is particularly advantageous in glass with a high SiO2 content. Therefore, according to one embodiment, the glass or glass substrate containing this glass-like material comprises at least 1.5% by weight of B2O3, advantageously at least 2.0% by weight of B2O3, particularly preferably at least 2.5% by weight of B2O3, and very preferably at least 5% by weight of B2O3. This is particularly preferable when a glass element obtained from or containing a glass substrate is used in a pressure sensor in which a corrosive medium comes into contact with the glass or glass element.

[0084] On the other hand, if the B2O3 content of the glass is too high, the etching properties of the glass decrease, which in turn slows down the manufacturing of the glass element and is therefore uneconomical, thus being disadvantageous. For this reason, the B2O3 content of the glass is advantageously limited, and according to further embodiments, it is 15% by weight or less.

[0085] In yet another embodiment, the glass substrate comprises glass having at least 2% by weight of Al2O3, wherein the Al2O3 content of the glass is advantageously limited to a maximum of 25% by weight.

[0086] Al2O3 is a preferred component because it prevents segregation, especially in borosilicate glass, and thus advantageously supports the productivity of the glass. Therefore, according to one embodiment, the glass or a glass element comprising this glass comprises at least 2% by weight of Al2O3. However, since Al2O3 is a component that can reduce the chemical resistance, especially the acid resistance, of the glass, it may be disadvantageous if the Al2O3 content of the glass or glass element is too high. This is particularly disadvantageous when the glass or a glass element comprising this glass comes into contact with a corrosive medium during use, as can occur, for example, in a pressure sensor in the exhaust gas region. Therefore, it is desirable that the Al2O3 content of the glass is 25% by weight or less.

[0087] According to a further embodiment, the cross-sectional area is at least 0.04 mm 2 and at most 2.7 mm 2 in average area. By doing so, a compact, i.e., small and space-saving, design of the pressure sensor becomes possible. Therefore, the equivalent diameter of such a cross-sectional area can be, for example, 0.3 mm to 0.9 mm.

[0088] According to yet another embodiment, the glass wafer comprises a plurality of openings, and the web width between the openings is at least 0.3 mm, preferably at least 0.5 mm and advantageously at most 7 mm, preferably at most 5 mm. This is advantageous because a plurality of openings can be efficiently manufactured simultaneously. Also, a glass wafer of a normal format can be well handled and shipped by an established process.

[0089] Making efficient use of the space of structured glass wafers or sheets, i.e., enabling as many individual elements as possible, is important in many applications because it directly relates to cost. It has been found that using almost square or rectangular holes, for example, square or rectangular holes with rounded corners, can increase the number of individual elements by a few percent compared to circular holes of the same area.

[0090] In a further embodiment, in a glass wafer having multiple openings, the ratio of the openings to the total area of ​​the glass elements is 0.1% to 12%, preferably 0.2% to 10%. This ensures sufficient stability of the glass wafer against normal handling processes.

[0091] In yet another embodiment, the thickness of the glass element or glass wafer is at least 200 μm, preferably at least 300 μm and up to 3500 μm, preferably up to 3000 μm, particularly preferably up to 2000 μm, very particularly preferably up to 1800 μm, and in the best case up to 1000 μm, so that the ratio of the thickness of the glass element / glass wafer to the average transverse dimension of the cross-sectional area, e.g., equivalent diameter, is at least 0.33 and up to 3. Here, the thickness of the glass element or glass wafer is, on the one hand, a decisive factor regarding the mechanical stability of the glass element or glass wafer, and therefore it is desirable not to be too small in order to avoid increased glass breakage. On the other hand, for reasons of cost and weight, and in order to realize small components such as pressure sensors, it is desirable not to be too large. Furthermore, it has been found that when a predetermined ratio occurs between the thickness of the glass element and the average transverse dimension of the cross-sectional area, not only the mechanical stability of the pressure sensor but also the quality of the measurement data of such a pressure sensor can be further improved. The average transverse dimension of the cross-sectional area can be the average equivalent diameter, for example, when the size of the cross-sectional area varies in the height direction of the opening. Representing the size of the cross-sectional area with an equivalent diameter is particularly advantageous in the case of a cross-sectional area having a polygonal shape, as is preferred according to this disclosure. Here, the equivalent diameter of the opening is the diameter of a circle having the same area as the cross-sectional area in question, but which is not circular. The thickness of the pressure sensor glass can be, for example, at least 0.4 mm and up to 0.9 mm, but thicknesses of 1.6 mm or 2.7 mm are also possible, and advantageously, a small thickness of, for example, 200 μm is preferred.

[0092] According to one embodiment, the glass wafer has a thickness variation of less than 10 μm, preferably less than 5 μm, particularly preferably less than 2 μm, and very particularly preferably less than 1 μm.

[0093] According to one embodiment, the side surface of the opening has an inclination angle, which is advantageously at most 2°, where the inclination angle means a deviation from an ideally upright side surface (or sidewall) that makes a 90° angle with the surface of the glass wafer.

[0094] According to further embodiments, at least one surface of the glass wafer and / or glass element is polished, and therefore advantageously has a roughness R of <2 nm, preferably <1 nm. a This has the following advantages: it corresponds to the surface of a glass element or glass wafer to which connection with a silicon diaphragm is planned.

[0095] This is advantageous because it results in a surface with very little roughness, which allows for particularly good connections. However, it has been found that polishing the surface of the glass wafer in this manner, especially in the area of ​​the openings, is critical because, in this case, chipping can occur, particularly in the edge area of ​​the openings, due to mechanical breakage of the glass. Surprisingly, it has been found that the combination of etched openings according to this disclosure and mechanical surface polishing, as described in more detail in the methods described later, is advantageous, in particular, because this combination of etching and mechanical polishing can reduce, and advantageously even completely prevent, chipping in the edge area.

[0096] Further embodiments include a glass wafer or glass element having at least one aperture, and a preferred method for manufacturing a glass element or glass wafer according to one embodiment, the method being - The step of providing a plate-shaped glass substrate, - A step of irradiating one of the surfaces of a plate-shaped glass substrate with laser light from an ultrashort pulse laser, wherein the laser light forms an elongated focal point within the plate-shaped glass substrate by a focusing optical system, thereby generating a single filament-like damage within the volume of the plate-shaped glass substrate due to the incident energy of the laser light, and the longitudinal direction of the filament-like damage is perpendicular to the surface of the plate-shaped glass substrate, and in order to generate a single filament-like damage, the ultrashort pulse laser is irradiated with a pulse packet having one pulse or at least two consecutive laser pulses, - A step of obtaining a plurality of adjacent filament-like damages on a predetermined line in a plate-shaped glass substrate by guiding the incident point of a laser beam along a predetermined closed line on the plate-shaped glass substrate, wherein the filaments are preferably extending from one surface to the other surface of the plate-shaped glass substrate, - A step of etching a plate-shaped glass substrate with a liquid etching medium in at least a region where filamentous damage is formed on the plate-shaped glass substrate, wherein the filamentous damage is spread to form channels, the diameter of the channels is widened by etching, and the glassy material of the plate-shaped glass substrate located between each channel is removed, and as a result, each channel is integrated to form the boundary of an opening having a cross-section with a cross-sectional region, where the cross-sectional region is defined by a straight portion, the straight portion having a minimum length of at least 10 μm, preferably at least 20 μm, or even more preferably at least 100 μm, the opening has sides, the sides have a surface, and the surface is preferably defined by the following formula

number

[0097] In this specification, filamentous damage means a long, thin damage. Generally, filament means a long, thin object or structure, where the length of the structure or object is at least one order of magnitude, and advantageously at least two orders of magnitude, greater than the spatial extent in two other dimensions perpendicular to the length of the object or structure, particularly the equivalent diameter of the cross-sectional area perpendicular to the length of the object or structure. Thus, in filamentous damage, the cross-sectional area is very small compared to the length of the damage.

[0098] The method described above has been demonstrated to be particularly advantageous. However, this application is not limited to this method. Other methods such as CNC drilling, ultrasonic vibration lapping, sandblasting, and local etching are also available.

[0099] By generating filamentous damage along predetermined lines within or on a plate-shaped glass substrate, the contour of openings formed within the plate-shaped glass substrate by this method can be determined very easily. In particular, this method can easily generate openings defined by straight lines, the straight lines having a minimum length of at least 10 μm, preferably at least 20 μm, or even more preferably at least 100 μm. However, other geometric shapes of openings are also possible, and in principle, this method can also generate openings of complex geometric shapes. However, advantageously, this method can generate polygonal cross-sectional shapes in particular, such as rectangular and / or square face shapes, and some may have rounded corners. This can be achieved in particular by a combination of appropriate selection of line shapes and etching of the glass material between each damage.

[0100] Advantageously, an alkaline etching medium is preferred as the etching medium.

[0101] Here, it was found that a particularly advantageous configuration of the surface on the side of the opening can be obtained, for example, by skillfully selecting the removal rate. Thus, according to one preferred embodiment, the glassy material of the glass element is removed at a removal rate of less than 5 μm per hour.

[0102] Alternatively or additionally, if the etching time is at least 12 hours, it can favorably influence the shape of the cross-sectional area of ​​the opening and / or the surface configuration of the sides of the opening.

[0103] Such processing can be carried out, for example, in a basic etching bath with a pH value of 12 or higher. An aqueous KOH solution is preferred, and the concentration of KOH is particularly preferably greater than 4 mol / l, particularly preferably greater than 5 mol / l, and very preferably greater than 6 mol / l, but it is desirable that the concentration be less than 30 mol / l. According to one embodiment, etching can be carried out at an etching bath temperature of greater than 70°C, advantageously greater than 80°C, particularly preferably greater than 90°C, but less than 100°C, regardless of the etching medium used.

[0104] In particular, the removal of the target material and / or the introduction of filamentous damage can also be influenced by the appropriate selection of the material. Glass with a high silicate content, i.e., glass with at least 50% by weight, preferably at least 55% by weight of SiO2, and particularly preferably at least 70% by weight of SiO2, has been found to be particularly suitable for the manufacture of glass elements according to this embodiment, especially by the method described above.

[0105] According to one embodiment, after etching, at least one surface, particularly the surface facing the silicon diaphragm of the pressure sensor, can be mechanically polished.

[0106] Here, a particularly advantageous glass composition may be when the glass is composed of borosilicate glass. This is because the combination of SiO2 and B2O3 content allows for a good balance between sufficient chemical resistance for subsequent use of the glass element, such as contact with corrosive media in pressure sensors in the automotive sector, while still exhibiting sufficient melting properties, and sufficient etchability in wet chemical etching processes. Therefore, it has been found that a glass element containing glass with 50% to 85% by weight of SiO2, preferably 78% to 83% by weight of SiO2, and 1.5% to 15% by weight of B2O3, preferably 2.0% to 15% by weight of B2O3, particularly preferably 2.5% to 15% by weight of B2O3, and very particularly preferably 5% to 15% by weight of B2O3 is advantageous.

[0107] Based on the known tendencies of borosilicate glass, it may be even more advantageous if the glass contains alternative components to prevent segregation. Therefore, advantageously, the glass or glass element according to one embodiment further contains Al2O3 as a component, in addition to the aforementioned SiO2 and B2O3 content, preferably at least 2% by weight of Al2O3. However, Al2O3 is also a component that can strongly affect the chemical resistance of the glass. Furthermore, it is known that Al2O3 in certain types of glass can improve chemical resistance, particularly in the alkaline range. Therefore, in order to ensure that the glass is still sufficiently etchable by alkaline etching media, it is desirable that the Al2O3 content of the glass not be too high, and thus advantageously, limited to a maximum of 25% by weight. Such glass containing SiO2, B2O3, and Al2O3 within the above limits has been found to be obtained in a surprisingly slow etching process, i.e., with a fairly low etching rate and / or long etching time, which has proven advantageous in forming a given surface configuration.

[0108] Glass elements containing or manufactured from glass containing the following components in weight percent were found to be particularly preferred for providing glass elements according to the embodiments and / or can be manufactured by the methods according to the embodiments: Composition range 1 SiO260~65 B2O36~10.5 Al2O3 14~25 MgO 0-3 CaO 0-9 BaO 3~8 ZnO 0~2 This is characterized by the total content of MgO, CaO, and BaO being in the range of 8 to 18% by weight. Composition range 2 SiO260~85 B2O35~20 Al2O3 2~15 Na2O 3~15 K2O 3-15 ZnO 0~12 TiO2 0.5~10 CaO 0~0.1 Composition range 3 SiO275~85 B2O38~15 Al2O3 2~4.5 Na2O 1.5~5.5 K2O 0~2 Composition range 4 SiO2 20-70, preferably 50-60, particularly preferably 52-58 B2O3 0.5-14, preferably 2-12, particularly preferably 2-4 Al2O3 15-41, preferably 16-24, particularly preferably 18-23 MgO 0.5-15, preferably 2-12, particularly preferably 3-5 CaO 0-5, preferably 0-3 BaO 0-7, preferably 0-6 ZnO 0-20, preferably 2-12, particularly preferably 8-10 NaO 0-7, preferably 1-6, particularly preferably 3-5

[0109] In all of the above compositional ranges, for example, in the form of colorants and / or clarifying agents, such as SnO2, CeO2, As2O3, Cl - F - It may also contain secondary components such as sulfates and / or trace components.

[0110] In general, it may be advantageous for the glassy material to be formed in such a way that it is anodic bondable (or bondable), without being limited to the composition range described herein. For this purpose, it may be advantageous for the glassy material to contain a certain proportion of alkali or alkali metal oxide, particularly sodium or sodium oxide. The Na2O content is preferably at least 0.5% by weight, but preferably not exceeding 6% by weight.

[0111] An advantageous embodiment of the present method is, alternatively or additionally, further, that the spatial distance between two incident points of laser light on at least one surface of the plate-shaped glass substrate is at most 6 μm, preferably at most 4.5 μm, and / or that the number of pulses of the burst for introducing filamentous damage is at most 2 or at least 7, and / or that the spatial distance between two incident points of laser light on at least one surface of the plate-shaped glass substrate is 1 μm to 15 μm, preferably at most 6 μm, for example at most 4.5 μm, and the pulse duration of the laser is in the range of 0.5 ps to 2 ps.

[0112] Another embodiment relates to a pressure sensor comprising at least one glass element according to one embodiment, for example, a piezoresistive or capacitive pressure sensor, advantageously a piezoresistive pressure sensor.

[0113] Such pressure sensors can generally be equipped with at least one silicon diaphragm.

[0114] Preferably, the glass element is formed such that the side surface of the opening has an inclination angle, and the inclination angle is advantageously up to 2°. Here, the inclination angle is the deviation from an ideally upright side wall that makes a 90° angle with the surface of the glass element.

[0115] Thus, the glass element is formed such that the area of ​​the opening on one surface of the glass element is larger than the area on the other surface of the glass element facing this first surface. In one embodiment, the pressure sensor may be formed such that the surface with the larger cross-sectional area of ​​the glass element faces the silicon diaphragm. This is also called an "inverted cone" shape. Surprisingly, this configuration has been found to be advantageous in terms of the mechanical stability of the pressure sensor and, consequently, the stability of the measurement results, compared to the opposite configuration in which the cross-sectional area of ​​the opening decreases toward the silicon diaphragm.

[0116] This is because if the opening of the glass element opposite the silicon diaphragm is larger than the opening of the glass element facing the silicon diaphragm, the opening acts like a nozzle, causing the pressure within the measurement cavity to fluctuate significantly over time. This can lead to inaccurate pressure measurements and increase the mechanical load on the silicon diaphragm.

[0117] Furthermore, it was found that it can be advantageous for the opening on the side opposite to one or more silicon diaphragms to be smaller than the opening facing one or more silicon diaphragms. For example, this provides a larger surface area for bonding with other components on the side of the glass element opposite to one or more silicon diaphragms. This is advantageous because it can improve the mechanical stability of the connection between the pressure sensor and other components.

[0118] However, according to further embodiments, it is also possible to provide a pressure sensor configured such that the side surface of the opening of the glass element has an inclination angle, preferably up to 2°, where the inclination angle is a deviation from an ideally upright side surface that makes a 90° angle with the surface of the glass wafer, and the opening has a cross-section having a tapered cross-sectional region in the direction of the silicon diaphragm. That is, according to this embodiment, the cross-sectional region of the opening is smaller on the side of the glass element facing one or more silicon diaphragms than on the side of the glass element facing one or more silicon diaphragms. This is advantageous because it can shorten the time to reach the maximum pressure in the pressure sensor. This can be illustrated by Figure 12, which will be described later in the Figure Description. In such a so-called "conical" embodiment of the opening, for example, it is possible to shorten the time to reach the maximum pressure at at least one point A, B of the silicon diaphragm provided in the pressure sensor by at least 30%, preferably even at least 40%, compared to the case where the cross-sectional region of the opening is constant or widened.

[0119] According to one embodiment, the pressure sensor comprises a glass element and a silicon diaphragm, and the shape of the silicon diaphragm teeth, Opening of glass element In accordance with It is formed in such a way that, as a result, the shape of the silicon diaphragm corresponds to the shape of the opening, in that the aspect ratio of the silicon diaphragm is equal to the aspect ratio of the opening.

[0120] Particularly advantageous is the case where the ratio of the cross-sectional area of ​​the cavity to the cross-sectional area of ​​the opening in the glass element is small, as described above regarding the technical advantages and effects of the geometric shape of the cross-sectional area. Advantageously, according to one embodiment, the ratio of the cross-sectional area of ​​the cavity to the cross-sectional area of ​​the opening is less than 10, preferably less than 5. Therefore, according to one embodiment, the pressure sensor is configured such that the cavity of the silicon diaphragm has a cross-sectional area, and the ratio of the cross-sectional area of ​​the cavity to the cross-sectional area of ​​the glass element is less than 10, preferably less than 5.

[0121] By using glass compositions corresponding to the above composition range, for example, the strain value Ssk shown in the table below can be obtained. Here, the composition range of the glass in the glass element or glass wafer is listed in the top row, respectively. A glass element according to an embodiment of the present disclosure was used for the measurement. Here, the surface of the side wall of the opening was measured in at least one region that may preferably belong to the straight portion of the opening. Here, the glass element was obtained by the method according to the present disclosure, i.e., by generating one or more filaments by laser processing and then performing an etching process. Different parameters were used during etching, as shown in the second row as "etching parameters".

[0122] Finally, there are further differences in the laser processing parameters for generating the filament at measurement points A to J. The samples shown in the following two tables demonstrate that the surface roughness of the sidewalls of the aperture can be adjusted in various ways.

[0123] [Table 3]

[0124] The present invention will be described in more detail below with reference to the drawings. Here, the same reference numerals refer to the same or corresponding elements. [Brief explanation of the drawing]

[0125] [Figure 1] This is a schematic diagram, not to exact scale, showing one embodiment of a glass wafer. [Figure 2] This is a schematic diagram, not to exact scale, showing one embodiment of a glass wafer. [Figure 3] This is a schematic diagram, not to exact scale, showing one embodiment of a glass wafer. [Figure 4] This is a schematic diagram, not to exact scale, showing one embodiment of a glass element. [Figure 5] This is a schematic diagram showing a portion of the glass element used to explain the tilt angle. [Figure 6] This is a schematic diagram, not to exact scale, showing one embodiment of a piezoresistive pressure sensor. [Figure 7] This is a schematic diagram, not to exact scale, illustrating a method for manufacturing glass wafers or glass elements. [Figure 8] This is a schematic diagram, not to an exact scale, showing a glass substrate as an intermediate product in a manufacturing method for glass wafers or glass elements. [Figure 9] This figure shows the height of structural elements in a 6'' wafer when transitioning from a circular opening to a rectangular opening with the same opening volume. [Figure 10] This figure shows the height of structural elements in a 6'' wafer when transitioning from a circular opening to a rectangular opening with the same opening volume. [Figure 11] This figure shows the behavior of a pressure sensor with a circular opening cross-section and various side wall inclination angles, relating to the time distribution of pressure shock. [Figure 12]This figure shows the behavior of a pressure sensor with a circular opening cross-section and various side wall inclination angles, relating to the time distribution of pressure shock. [Figure 13] This figure shows the behavior of a pressure sensor with a circular opening cross-section in relation to the time distribution of pressure impact, in comparison to the behavior of a pressure sensor with a square opening cross-section. [Figure 14] This figure shows the behavior of a pressure sensor with a circular opening cross-section in relation to the time distribution of pressure impact, in comparison to the behavior of a pressure sensor with a square opening cross-section. [Figure 15] This diagram illustrates different area ratios between the cross-sectional area of ​​the cavity and the cross-sectional area of ​​the opening.

[0126] Figures 1 to 3 show schematic, not precisely scaled, views of a glass wafer 10 having multiple openings 2. Each opening 2 (not all shown for clarity) has, here exemplary, a cross-sectional region 3, defined by a linear portion 31, which has a minimum length of at least 10 μm, preferably at least 20 μm, or even more preferably at least 100 μm. In the glass wafer 10 shown in Figures 1 and 2, each cross-sectional region 3 of an opening 2 is defined by four linear portions 31 (not all shown for clarity), so each cross-sectional region 3 has a rectangular shape, and here exemplary, a rectangular shape with rounded corners. However, other cross-sectional regions are also conceivable, such as circular segments or generally polygonal cross-sectional regions 3 as illustrated in Figure 3 for the openings 2. For clarity, the apertures 2 are shown here as larger than the glass wafer 10; however, when manufacturing small components such as compact pressure sensors, it is common to make the apertures 2 smaller relative to the dimensions of the glass wafer 10. The typical equivalent diameter of the apertures 2 may be less than 1 mm. Furthermore, a straight line 32 is shown. Therefore, it is also possible to understand that the straight section 31 is part of the straight line 32.

[0127] Figures 1 to 3 each show an embodiment of a glass wafer 10 having multiple openings 2. Therefore, these glass wafers 10 are semi-finished products for manufacturing frame-shaped glass elements 100, each having only one opening 2. The glass wafers 10 shown in Figures 1 to 3 enable high-speed and low-cost manufacturing. This is advantageous because it allows for the efficient simultaneous manufacturing of multiple openings, and also simplifies the handling and shipping of the glass wafers. Subsequently, customers can perform individual component assembly and assembly into small parts such as pressure sensors as needed.

[0128] Figure 4 shows a schematic, not precisely scaled, diagram of one embodiment of a frame-like glass element 100 having only one opening 2. The glass element 100 comprises a plate-shaped glass substrate 1, the glass substrate 1 comprising a surface (or main surface or face) 11 and a further surface 12 facing this first surface 11. Advantageously, the glass element 100 or glass substrate 1 may be formed such that the surfaces 11 and 12 are parallel to each other within normal manufacturing tolerances. Since the glass element 100 (or glass substrate 1) is positioned horizontally here, in this case the surface 11 can also be called the top surface and the surface 12 the bottom surface.

[0129] In Figure 4, the glass element 100 is shown in a cross-sectional view passing through the opening 2. The opening 2 has a side surface 4, and the side surface 4 has a surface 41, which is advantageously given by the following equation

number

[0130] Figure 5 schematically shows the surface 41 of side 4, with dots marking the surface in the top view.

[0131] The side surface 4 of the glass element 100 shown in Figure 4 is inclined. In other words, side surface 4 has an inclination angle, although for clarity this angle is not shown in Figure 4. This is because the inclination angle of the side surface (or side wall) 4 of the opening 2 is advantageously small.

[0132] Figure 5 shows a schematic, albeit not precise, detail of a portion of the glass element 100 (or glass wafer 10) to illustrate the inclination angle 51 of side surface 4 in more detail. Here, the dashed line 5 indicates the extension of a hypothetical side wall (not shown) that is ideally upright, i.e., extends perpendicular (angle 52) to the surfaces 11 and 12 of the glass element 100 (or glass substrate 1). This line 5 (which can also be interpreted geometrically as the "height" of a triangle having sides 4, 5 and 110, and in relation to the glass element 1, as the thickness of the glass element 1) and the side wall 4 of the glass element 100 (or glass substrate 1) form an angle 51. This angle 51 is also called the inclination angle. Thus, this angle indicates the magnitude of the deviation from the ideally upright side wall that forms a 90° angle with the surfaces 11 and 12 of the glass element 100. Advantageously, the inclination angle is at most 2°, meaning the inclination of side surface 4 is very slight. As a result, the size of the cross-sectional area 3 of the opening 2 changes only slightly in the height direction of the opening 2. In some cases, an embodiment in which the cross-sectional area is the same on both sides 11 and 12 of the glass element 100 within the range of normal manufacturing tolerances is preferred. However, when the glass element 100 is used in a piezoresistive pressure sensor in particular, it may be advantageous to have a larger cross-sectional area 3 on one surface of the glass element 100.

[0133] Figure 6 shows an exemplary pressure sensor 6 in a schematic diagram not to exact scale. The pressure sensor 6 is shown in a cross-sectional view and includes a base 60, which may be made of, for example, a ceramic material. A glass element 100 is fixed to the base 60 by an adhesive layer 63, for example, made of epoxy resin. The glass element 100 has an opening 2, where the side wall 4 is inclined, so the cross-sectional area 3 (not shown) of the opening 2 is larger on the surface 11 than on the surface 12 of the glass element 1. Therefore, the size of the opening 2 increases toward the measuring cavity 600 of the pressure sensor 6 or toward the silicon diaphragm 62. The pressure sensor 6 optionally further includes another silicon diaphragm 61, which forms a reference pressure cavity 601.

[0134] Without being limited to the illustrated examples, the pressure sensor 6 according to this disclosure may be formed in particular as a piezoresistive or capacitive pressure sensor and may comprise at least one glass element 100 according to this disclosure, the glass element 100 having an opening 2 and its surface having a non-zero strain structure as described herein. In this case, the glass element 100 is connected to an element having a deformable diaphragm for pressure measurement. According to one preferred embodiment, a silicon element or silicon diaphragm 61 having a deformable diaphragm portion 610 is provided. In particular, an element such as a silicon diaphragm 61 is anodized to the glass element 100. Regardless of the type of connection, the surface of the glass element 100 connected to the diaphragm is mechanically polished according to one preferred embodiment. This allows for a particularly stable connection by anodization. Anodized connection can be identified by the fact that the surfaces of both elements are directly connected or in direct contact with each other. As a result, the element connected to the glass element 100, for example, the silicon diaphragm 61 in particular, has a cavity 600 through which the opening 2 is connected.

[0135] Figure 7 illustrates the manufacturing of a glass element 100 or a glass wafer 10 according to one embodiment of the method.

[0136] In the method for manufacturing a glass element 100 or a glass wafer, the laser light 80 of an ultrashort pulse laser 8 is irradiated onto one of the surfaces 11 or 12 of a plate-shaped glass substrate 1. At this time, the laser light 80 forms an elongated focal point within the plate-shaped glass substrate 1 by a focusing optical system 81. In this way, the incident energy of the laser light 80 generates filamentous damage 70 within the volume of the plate-shaped glass substrate 1, the filamentous damage 70 whose longitudinal direction is perpendicular to the surfaces 11 or 12 of the plate-shaped glass substrate 1. At this time, in order to generate the filamentous damage 70, the ultrashort pulse laser 8 is irradiated with a pulse packet having one pulse or at least two consecutive laser pulses. By guiding the incident point 82 of the laser light 80 along a predetermined closed line 71 on the plate-shaped glass substrate 1, a plurality of adjacent filamentous damage 70 are obtained on the plate-shaped glass substrate 1 along the predetermined line 71. At this time, the filaments 71 advantageously extend from one of the surfaces 11 or 12 of the plate-shaped glass substrate 1 to the other surface 11 or 12. The operation of the incident point 82 on this closed line 71 can be performed, for example, by a positioning unit 9. This can be controlled, for example, by a calculation unit 91. It is also reasonable that the calculation unit 91 can control the laser output. Furthermore, it is naturally possible to use multiple calculation units 91.

[0137] In a further process, etching of the plate-shaped glass substrate 1 is performed with a liquid etching medium in at least the regions where filamentous damage 70 is formed on the plate-shaped glass substrate 1, thereby expanding the filamentous damage 70 and forming channels. The diameter of the channels is widened by etching, and the glassy material of the plate-shaped glass substrate 1 located between each channel is removed. As a result, each channel is integrated to form the boundary of an opening 2 having a cross-section with a cross-sectional region 3, where the cross-sectional region 3 is defined by a linear portion 31, which preferably has a minimum length of at least 10 μm, particularly preferably at least 20 μm, or even more preferably at least 100 μm, the opening 2 has a side surface 4, which has a surface 41, and the surface 41 is preferably defined by the following formula

number

[0138] The predetermined closed line 71 forms the contour of the cross-sectional region 3.

[0139] After the steps shown and described in Figure 7, at least one of the glass element or glass wafer surfaces can be polished. Figure 8 is a top view of a plate-shaped glass substrate 1 with multiple filamentous damages 70 introduced. For clarity, not all of these are illustrated. The filamentous damages 70 are introduced into the glass substrate 1 in such a manner that they are applied along closed lines 71 that form a rectangular contour with rounded corners, in this example. For the glass substrate shown in Figure 7 as an example, the filamentous damages 70 are introduced along four closed lines 71, so that in the subsequent etching process, a glass wafer with four openings will be produced in this case. Of course, the number of openings can be adapted depending on the size of the openings, the size and shape of the plate-shaped glass substrate, in particular to achieve efficient use of space.

[0140] In general, such methods involving filament formation and subsequent etching processes are advantageous because they allow for smaller radii at the corners of the openings, which can be particularly advantageous when manufacturing cross-sectional areas having at least one straight section. The minimum radius achievable with conventional USSL processes is 150 μm. In contrast, the described method allows for radii of less than 150 μm, preferably less than 100 μm. The lower limit of the corner radius can generally be 20 μm.

[0141] Figures 9 and 10 illustrate the advantages of transitioning from a circular opening to an opening having a cross-section with a cross-sectional region, wherein the cross-sectional region is defined by at least one linear portion, the linear portion having a minimum length of at least 10 μm, preferably at least 20 μm, or even more preferably at least 100 μm, from the perspective of wafer occupancy density. The dimensions of the opening in the left region of Figure 9 are 500 μm × 420 μm, and the corner radius is 90 μm. The radius of the opening in the right region of Figure 9 is 254.2 μm. Flow channel area (203,000 μm in this example) 2Considering that the dimensions are equal and the web width from the opening wall to the edge of the pressure sensor base (750 μm in this case) is equal, for openings that are not perfectly circular, i.e., openings whose cross-sectional area is defined by at least one straight section, each base is several percent smaller laterally. Similarly, when this is applied to a 6-inch wafer, several percent more effective space can be utilized (Figure 10), leading to cost reduction. Figure 9 also shows percentage figures. These relate to the total area of ​​the glass element for the dimensions of the glass element shown in Figure 9. This is 5% larger for circular openings. Considering only the bondable or connectable area of ​​the glass element (i.e., minus the cross-sectional area of ​​the opening), for the dimensions of the opening shown in Figure 9, this is 5.3% larger for circular openings. Figure 10 shows that when the opening shape is circular, the number of openings that can be realized on a wafer with otherwise the same web width is reduced by 4% compared to openings where the cross-sectional area shown in the left part of Figure 10 is not perfectly circular.

[0142] Figures 11 and 12 show the fluid dynamics calculations and corresponding models for an exemplary axisymmetric pressure sensor cavity, contrasting the case with a circular pedestal opening with upright walls and the case with a pedestal opening with inclined walls. As an exemplary medium, substantially incompressible water flowing in a laminar manner is used here. This water flows into the cavity at 30 bar, where it is dispersed non-uniformly over time due to reflection off the walls. Two exemplary points A and B, one in the center and the other to the side of the cavity diaphragm, are subjected to pressures that differ over time. Here, complete pressure equilibrium is achieved within a few microseconds.

[0143] In the first approximation, the time to pressure equilibrium is of the same order regardless of the shape of the opening (vertical wall or wall inclined upward or downward). However, in the case of very delicate pressure measurements requiring extremely high precision, even slight deviations can sometimes have significant effects. Surprisingly, it has been found that the time to reach maximum pressure is shorter, especially in the case of structures with a slightly conical shape. On the other hand, in the case of tapered structures, it causes higher pressure fluctuations before reaching perfect pressure equilibrium.

[0144] Furthermore, if it is desirable to reach pressure equilibrium more quickly, openings are advantageous not only because of their tapered cross-section, but also because, even if the walls are upright, they essentially have a smaller cross-sectional area.

[0145] Furthermore, surprisingly, calculations revealed that using very high frequencies, i.e., applying pressure shocks with frequencies exceeding 100 kHz as in this exemplary case, is undesirable because it can result in extremely chaotic conditions. In such applications, the cross-sectional shape of the opening is preferably one that can at least reduce, and preferably minimize, the fluctuations.

[0146] At the top of Figure 11, there is a height h. si An exemplary figure of a measuring cavity 600 having is shown. The measuring cavity 600 is formed, here exemplary, to be rotationally symmetric about the axis of symmetry 605. In the upper region of the measuring cavity 600, the measuring cavity 600 has a radius r0. Thus, the measuring cavity 600, here exemplary, has a lower radius r a It is formed in the shape of a straight frustum of a cone, such that the angle is greater than r0. The measuring cavity 600 is followed by the area of ​​opening 2 below. The height of opening 2 is h gl This corresponds to the thickness of the glass element (not shown here). The opening 2 is also formed to be rotationally symmetric about the axis 605 in this case as well, and therefore the radius r u It has the shape of a cylindrical body.

[0147] In the lower part of Figure 11, three different cases are distinguished for the configuration of opening 2 (not shown here). The dimensions for the case where the side is not inclined are those described above for the upper part of Figure 11. This case is shown in the lower left part of Figure 11 in the form of a schematic cross-sectional view and is labeled "upright." In the lower center of Figure 11, the radius r of the cross-sectional area of ​​the opening in the direction of the silicon diaphragm or measuring cavity (neither shown) is shown. t radius r u A case is shown in which the side of opening 2 (not shown) is inclined to be smaller than r. In other words, the cross-sectional area of ​​the glass element facing the measurement cavity is smaller than the cross-sectional area of ​​the glass element on the opposite side of the measurement cavity. This is what is collectively referred to here and below as "conical," for example, when the opening has a cross-section that has a cross-sectional area, and that cross-sectional area is defined by at least one straight portion. Finally, in the lower right of Figure 11, conversely, r u ga r t A smaller case is shown. This is referred to here and below as an inverted cone, even when the shape of the cross-sectional area deviates from a circle, for example, when the opening has a cross-section that has a cross-sectional area, and that cross-sectional area is defined by at least one straight portion. As already mentioned above, when considering the calculations, it has been found that in the case of the so-called "conical" embodiment of the opening, for example, it is advantageous to reduce the time to reach the maximum pressure at at least one point A, B of the silicon diaphragm of the pressure sensor by at least 30%, preferably even at least 40%, compared to the case where the cross-sectional area of ​​the opening is constant or widened. Herein, such an embodiment of the pressure sensor may be advantageous. However, the opposite case, the "inverted conical" embodiment, may also be advantageous in this case because the pressure fluctuation is smaller.

[0148] Figures 13 and 14 show a fluid dynamics simulation of an opening with a circular cross-section, in comparison to a fluid dynamics simulation of an opening with a rectangular cross-section. The upper part shows a measurement cavity with a circular cross-section, corresponding to the upper part of Figure 11. On the other hand, the lower part of Figure 13 shows a case where the cross-sectional shape of the opening or measurement cavity deviates from a circle; that is, the opening or measurement cavity has a cross-section with a cross-sectional region, characterized by at least one linear segment, in this case four linear segments. As can be seen exemplarily from the schematic diagram of the right-hand portion in the lower part of Figure 13, the corners of the corresponding cross-sectional regions are rounded in this case. Because the cross-sectional shapes are different, the radius R of the corners is used here to characterize the rounding of the corners. r Only is shown, but otherwise it is dimension b, not radius. a , b u Or b0 is indicated, and in this case, these are half the length of the upper edge of the measurement cavity (b0) and half the length of the lower edge of the measurement cavity (i.e., in the direction of the glass element) (b a ), and half the edge length of the opening of the glass element (b u ) Here, the simulation conditions are the same as in the description of Figures 11 and 12, except that the cavity and inflow opening in the silicon are not ideally circular, i.e., they exhibit at least one straight edge or straight portion 31. The flow cross-sectional area is the same in both models.

[0149] Similar to the calculations in Figures 11 and 12, pressure equilibrium is performed within a microsecond time window. In this case, point B at the edge of the cavity fluctuates less than point A at the center, which means that the overall back reflection is smaller. At A, the advantage of the non-angular aperture is particularly evident, namely, the significant attenuation of high-frequency fluctuations, allowing for more reliable and accurate monitoring of high-frequency applications.

[0150] According to the present invention, surprisingly, geometric influences are also important, namely the cross-sectional shape of the opening, as well as the surface morphology of the opening or its sidewalls or sides themselves. Surprisingly, it can be recognized that asymmetric conditions / ratios of peaks and valleys can positively counteract the chaotic state described above. For example, an ideally non-smooth structure can introduce a turbulent component. Matching this turbulent component with shape effects, or selecting it as intended, can result in ideal pressure application to the sensor cavity or high-sensitivity Si diaphragm in terms of pressure magnitude, saturation, and fluctuation.

[0151] Figure 15 schematically shows, without precise scale, the cross-sectional area 603 of the measurement cavity 600 (not shown) and the cross-sectional area 3 or 3a of the glass element 100. Figure 15a) shows a top view of the cross-sectional area 603 of the pressure sensor's measurement cavity. Similarly, the cross-sectional area 3 of the opening 2, in this case centrally located, is shown (opening 2 is not shown). The circular cross-sectional area 3 of the opening in the glass element is smaller here than the cross-sectional area 603 of the cavity. Also shown is a hypothetical rectangular cross-sectional area 3a of opening 2 (not shown here), with side lengths corresponding to the diameter of the circular opening 3. As a result of the difference between cross-sectional areas 603 and 3 (or 603 and 3a), a free area 604 is created, i.e., an area where a force can act when pressure is applied.

[0152] Figure 15b) shows the corresponding illustration, however, the difference is that the resulting free region 604 is significantly smaller than in Figure 15a). That is, in this case, the ratio of the two cross-sectional regions 603 and 3 (or 603 and 3a) is significantly smaller than in the illustration of Figure 15a). As already explained above, the advantages of an opening with at least one straight section, such as a rectangular opening or rounded corners, are particularly evident in Figure 15b). This is because, as can be seen, changing from a circular or rounded cross section to a cross section with at least one straight section is particularly effective in reducing the resulting free region 604, especially in this case. [Explanation of Symbols]

[0153] 1. Plate-shaped glass substrate 10 glass wafers 100 glass elements 11,12 surface 110 Sides of a triangle 2 openings 3,3a Cross-sectional area 31 Straight section / straight edge 32 straight line 4. Side walls, sides 41 Surface of the side wall 431 Region corresponding to the straight section 5 Thickness 51 angle, slope angle 52 angles, right angles 6. Pressure Sensor 60 base 61,62 Silicon diaphragm 63 Adhesive layer, adhesive 600,601 Measuring Cavity 603 Cavity cross-sectional area 604 The resulting free region 605 Axis of Symmetry 610 Deformable diaphragm section 70 Filamentous damage, filament 71 Closed lines, outlines 8 lasers 80 Laser light 81 Focusing Optical System 82 Point of incidence 9 Positioning Unit 91 arithmetic units A, B Points on the silicon diaphragm h si Height of the silicon diaphragm h gl Height of glass element r u Radius of the opening on the opposite side of the silicon diaphragm r a Radius of the cavity measured on the side facing the glass element. r t Radius of the opening on the side facing the measurement cavity r o Radius of the cavity measured on the opposite side of the glass element. b u Half the dimensions of the opening on the opposite side of the silicon diaphragm. b a Half the dimension of the measurement cavity on the side facing the glass element. b o Half the dimensions of the measurement cavity on the opposite side of the glass element. R r radius of the corner

Claims

1. A glass wafer (10) for manufacturing a frame-shaped glass element (100) used in a pressure sensor (6), wherein the glass wafer (10) comprises a plate-shaped glass substrate (1) and at least one opening (2) extending from one surface (11) of the glass substrate (1) to the other surface (12) of the glass substrate (1), the opening (2) having a cross section having a cross section region (3, 3a), the cross section region (3, 3a) being defined by a straight portion (31), the straight portion (31) having a minimum length of at least 10 μm, the opening (2) having a side surface (4), the side surface (4) having a surface (41), and the surface (41) having a strain value Ssk [Math 1] It is characterized in that it is not 0, and the value of the skewness Ssk is at least 0.001 and at most 5. The aforementioned strain is determined in the flat region of the side surface (4). Here, S ｑ A represents the mean square roughness of the surface, i.e., the RMS value; A represents the area of ​​the integration region for calculating the strain; Z(x,y) represents the respective height values ​​of the surface profile at coordinates x,y, and the height values ​​are shown based on the arithmetic mean of the height values ​​of the surface profile. If a point in the surface profile is higher than the average value, the corresponding value Z(x,y) is positive, and if the point is lower than the average value, the corresponding value Z(x,y) is negative, in a glass wafer (10).

2. The glass wafer (10) according to claim 1, wherein the cross-sectional region (3, 3a) is defined by at least two straight portions (31), and the straight portions (31) form an angle with a radius of curvature of at least 10 μm and at most 1000 μm.

3. The glass substrate (1) contains at least 50% by weight of SiO ２ Includes glass having SiO ２ The content is up to 85% by weight of SiO ２ of SiO ２ A glass wafer (10) according to claim 1 or 2, which is limited to the following.

4. The glass substrate (1) contains glass having at least 1.5% by weight of B ２ O ３ and the B ２ O ３ content of the glass is limited to a maximum of 15% by weight. The glass wafer (10) according to any one of claims 1 to 3

5. The glass substrate (1) contains at least 2% by weight of Al ２ O ３ Includes glass having Al ２ O ３ The glass wafer (10) according to any one of claims 1 to 4, wherein the content is limited to a maximum of 25% by weight.

6. The cross-sectional region (3, 3a) is at least 0.04 mm ２ And up to 2.7 mm ２ A glass wafer (10) according to any one of claims 1 to 5, having an average area.

7. The glass wafer (10) according to any one of claims 1 to 6, wherein the glass wafer (10) comprises a plurality of openings (2), and the web width between the openings (2) is at least 0.3 mm and at most 7 mm.

8. The ratio of the opening (2) to the total area of ​​the glass wafer (10) is 0.1% to 12%, according to any one of claims 1 to 7.

9. The glass wafer (10) according to any one of claims 1 to 8, wherein the thickness of the glass substrate (1) is at least 200 μm, and therefore the ratio of the thickness of the glass substrate (1) to the average horizontal dimension of the opening is at least 0.33 and at most 3.

10. The glass wafer (10) has a thickness variation of less than 10 μm, as described in any one of claims 1 to 9.

11. The glass wafer (10) according to any one of claims 1 to 10, wherein the side surface (4) of the opening (2) has an inclination angle, the inclination angle being a maximum of 2°, where the inclination angle is the deviation from an ideally upright side surface (4) that forms a 90° angle with the surface (11, 12) of the glass wafer (10).

12. A glass element (100) separated from a glass wafer (10) according to any one of claims 1 to 11, wherein the glass element (100) is a frame-shaped element having an opening (2), the opening (2) having a cross section having a cross section region (3, 3a), the cross section region (3, 3a) being defined by a straight portion (31), the straight portion (31) having a minimum length of at least 10 μm, the opening (2) having a side surface (4), the side surface (4) having a surface (41), and the surface (41) having a strain value Ssk [Math 2] It is characterized in that it is not 0, and the value of the skewness Ssk is at least 0.001 and at most 5. Here, S ｑ A represents the mean square roughness of the surface, i.e., the RMS value; A represents the area of ​​the integration region for calculating the strain; Z(x,y) represents the respective height values ​​of the surface profile at coordinates x,y, and the height values ​​are shown based on the arithmetic mean of the height values ​​of the surface profile. If a point in the surface profile is higher than the average value, the corresponding value Z(x,y) is positive, and if the point is lower than the average value, the corresponding value Z(x,y) is negative. (Glass element (100)).

13. A method for manufacturing a glass wafer (10) according to any one of claims 1 to 11 or a glass element according to claim 12, wherein the method is: - A step of providing a plate-shaped glass substrate (1), - A step of irradiating one of the surfaces (11, 12) of the plate-shaped glass substrate (1) with laser light (80) of an ultrashort pulse laser (8), wherein the laser light (80) forms an elongated focal point within the plate-shaped glass substrate (1) by a focusing optical system (81), so that the incident energy of the laser light (80) generates a single filament-shaped damage (70) within the volume of the plate-shaped glass substrate (1), and the longitudinal direction of the filament-shaped damage (70) is perpendicular to the surfaces (11, 12) of the plate-shaped glass substrate (1), and in order to generate a single filament-shaped damage (70), the ultrashort pulse laser (8) is irradiated with a pulse packet having one pulse or at least two consecutive laser pulses, - A step of obtaining a plurality of adjacent filament-like damages (70) on the plate-shaped glass substrate (1) by guiding the incident point (82) of the laser beam along a predetermined closed line (71) on the plate-shaped glass substrate (1), wherein the filaments (71) extend from one surface (11, 12) to the other surface (11, 12) of the plate-shaped glass substrate (1), - A step of etching the plate-shaped glass substrate (1) with a liquid etching medium in at least the region where filamentous damage (70) is formed on the plate-shaped glass substrate (1), wherein the filamentous damage (70) is widened to form channels, the diameter of the channels is widened by etching, and the glassy material of the plate-shaped glass substrate (1) located between each channel is removed, as a result the channels are integrated to form an opening (2) having a cross section with a cross section region (3), wherein the cross section region (3) is defined by at least one straight line (31), the opening (2) has a side surface (4), the side surface (4) has a surface (41), and the surface (41) has a strain value Ssk [Math 3] The step is to ensure that is not zero, and that the value of the skewness Ssk is at least 0.001 and at most 5, - Optionally, the glass substrate (1) is broken down into individual pieces to obtain glass elements (100). Includes, Here, S ｑ The method involves the following: is the mean square roughness of the surface, i.e., the RMS value; A is the area of ​​the integration region for calculating the strain; Z(x,y) is the height value of the surface profile at coordinates x,y, and the height value is shown based on the arithmetic mean of the height values ​​of the surface profile. If a point in the surface profile is higher than the average value, the corresponding value Z(x,y) is positive, and if the point is lower than the average value, the corresponding value Z(x,y) is negative.

14. The following features: - Remove the glassy material from the plate-shaped glass substrate (1) at a removal rate of less than 5 μm per hour, and / or - The etching time is at least 12 hours, and / or - The spatial distance between the two incident points of the laser beam on the at least one surface (11, 12) of the plate-shaped glass substrate (1) is a maximum of 6 μm, and / or - The number of burst pulses for inducing the filamentous damage is at most 2 or at least 7, and / or - The spatial distance between the two incident points of the laser beam on at least one surface (11, 12) of the plate-shaped glass substrate (1) is 1 μm to 15 μm, and the pulse duration of the laser is in the range of 0.5 ps to 2 ps. - Mechanically polish at least one surface (11, 12) The method according to claim 13, characterized by at least one of the above.

15. A pressure sensor (6) comprising at least one glass element (100) according to claim 12.

16. In the opening (2) of the glass element (1), the side surface (4) of the opening (2) has an inclination angle, the inclination angle being a maximum of 2°, where the inclination angle is the deviation from the ideally upright side surface (4) that forms a 90° angle with the surface (11, 12) of the glass wafer (10). The pressure sensor (6) comprises a silicon diaphragm (61, 62), The opening (2) has a cross-section having a tapered cross-sectional region (3, 3a) in the direction of the silicon diaphragm (61, 62), thereby making it possible to shorten the time it takes for the pressure sensor (6) to reach maximum pressure at at least one point (A, B) of the silicon diaphragm (61, 62) by at least 30% compared to when the cross-sectional region (3) of the opening (2) is constant or widened. or The pressure sensor (6) according to claim 15, wherein the opening (2) has a cross section having a cross section region (3, 3a) that extends in the direction of the silicon diaphragm (61, 62), thereby making it possible to increase the sensitivity of the pressure sensor (6) by at least 5% compared to a pressure sensor (6) in which the cross section region (3) of the opening (2) is constant or tapered.

17. The shape of the silicon diaphragm (61, 62) is formed to match the opening (2) located below it, and the shape of the silicon diaphragm (61, 62) corresponds to the shape of the opening (2) in such a way that the aspect ratio of the silicon diaphragm (61, 62) is equal to the aspect ratio of the opening (2). The pressure sensor (6) according to claim 16.

18. The following features: - The cavity (600) of the silicon diaphragm (61) has a cross-sectional region (603), and the ratio of the cross-sectional region (603) of the cavity (600) to the cross-sectional region (3, 3a) of the glass element (100) is less than 10. - The silicon diaphragm (61) is anodic-bonded to the glass element (100). A pressure sensor (6) according to claim 16 or 17, characterized by at least one of the following.

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