Glass microstructure, micro-mechanics and related uses

Abstract

Micromechanical microstructure (1) made of glass, in particular configured as a movable finger (24) of a micromechanical comb structure (25) or as a micromechanical bending structure (23), in particular as a cantilever, wherein the microstructure (1) was exposed from a glass substrate (3) by laser-induced modification of the glass substrate (3) and subsequent wet chemical anisotropic etching, characterized in that, for the production of the microstructure (1), laser pulses (4) were placed on two opposing toolpaths (5a, 5b) in a deflection region (12) of the microstructure (1), which have a respective maximum distance r perpendicular to a contour (6) along a direction (2) of the microstructure (1), corresponding to an etching radius (27) r of the wet chemical etching step,- wherein the etch radius (27) r lies in a substrate plane (28) of the glass substrate (3) and- wherein the contour (6) after wet chemical exposure shows lateral concave indentations (8), each exhibiting a curvature with the etch radius (27) r and bounded by respective convex ribs (9), and- that the laser pulses (4) were positioned such that the expression of a sidewall scalloping of the microstructure (1) is selectively adjusted in order to improve the homogeneity of the mechanical properties of the microstructure (1) or to selectively create an inhomogeneity of the mechanical properties of the microstructure (1),- wherein the sidewall scalloping is defined as a ratio ty / r of the local etch radius (27) r and a respective lateral depth ty(14) of the respective indentation (8).,

Description

The invention relates to a microstructure made of glass, which can be designed in particular as a micromechanical bending structure (which can form a micromechanical spring element, for example) or, for example, as a movable finger of a micromechanical comb structure or as a cantilever. The microstructure is (completely / overall) etched free from a glass substrate by means of laser induced deep etching (LIDE), that is to say by means of laser-induced deep etching, that is to say is exposed by laser-induced modification of the glass substrate and subsequent wet-chemical anisotropic etching.The invention further relates to a (movable) microelectromechanical system which (at least) has such a microstructure, a specific use of such a microelectromechanical system, which can likewise be produced by means of the LIDE method, and finally an associated production method.The LIDE method is known in the prior art, for example from the patent specification EP 2964417 B1. Up to now, it has been frequently used to etch structures in glass substrates, which structures form a housing of a sensor, for example.The invention is concerned with how the applications of the LIDE method can be extended.In the LIDE method, a material change (modification) is introduced (optically) into the glass body with the aid of a single laser pulse, typically over the entire thickness of a glass substrate, which material change has the result that, in a subsequent wet-chemical etching step, the structure in the glass substrate that has thus been optically pretreated / exposed with the laser can be anisotropically etched, although the etching solution actually exhibits isotropic etching properties in the glass substrate. With this technique, for example, high quality through vias can be produced in glass, which is of interest for hermetic packaging (AVT).In the LIDE method, pulsed lasers can be used, wherein the glass is then modified along the z-direction (=optical axis / surface normal of the glass substrate) with each laser shot (a laser pulse). In this case, typically no change of the beam profile used is used. In the LIDE method, therefore, in particular no individual small volumes (voxels) within the glass volume are processed differently with the laser, as in other laser-based (e.g. ablative) glass processing methods. The optical processing of the glass substrate is thus carried out non-ablatively in the LIDE method, i.e. the desired material removal in the glass substrate is only achieved later during the wet chemical etching step, but not by means of the laser radiation.WO 2022 022 873 A1 describes how cavities can be etched into a glass substrate with the aid of the LIDE method in order thereby to reduce the glass thickness in a targeted manner and thus to form a solid state joint in the glass substrate, which is of interest, for example, for the development of foldable displays.DE 10 2019 111 634 A1, on the other hand, describes the introduction of conical recesses on a microscopic scale into a glass substrate with the aid of the LIDE method in a first process step, followed by the application of a functional covering layer to the front side of the glass substrate already preetched in this way, wherein the functional, in particular electrically conductive, covering layer, since it does not consist of glass, can resist a further etching attack in a second wet chemical etching step with which further corresponding conical recesses are introduced into the glass substrate on the rear side. Since the cover layer covers the bottom of the original front-side respective recess, but is simultaneously exposed on the rear side, the cover layer forms a free-standing microscopic overhang structure, which can be used as a sensory element. The glass substrate here serves as a carrier and suspension point of the sensor element formed by the covering layer.An approach comparable to DE 10 2019 111 634 A1 is described by U.S. Pat. No. 2021 0 347 637 A1: here too, a front-side functional thin film which forms a membrane is deposited on a glass substrate and then exposed by structuring the glass substrate on the rear side with the aid of the LIDE method. In contrast to DE 10 2019 111 634 A1, however, here no first structuring is effected by means of LIDE before the membrane layer is applied, but rather the membrane layer is applied to the initially unetched front side of the glass substrate, resulting in a planar membrane.U.S. Pat. No. 2022 0 009 771 A1, on the other hand, uses the approach of arranging a semiconductor substrate, which has a functional layer forming the movable and sensory parts of the microphone, between a further semiconductor substrate and a glass substrate for the production of mechanically more robust MEMS (microelectromechanical systems) microphones, wherein the glass substrate is previously modified with the aid of a laser and bonded to the central semiconductor substrate. After the rear-side removal of the outer, further semiconductor substrate, the glass substrate thus carries the dedicated MEMS structures of the functional layer. After metallization and passivation layers have been applied on the rear side for electrically contacting the functional layer, the previously modified regions in the glass substrate are subsequently wet-chemically etched free, as a result of which the MEMS structures of the functional layer are exposed on the rear side. In this approach, a substrate processed by means of LIDE thus serves as a carrier for a classic functional layer made of a semiconductor material such as silicon and increases the mechanical robustness of the overall sensor system. However, the movable structures are defined exclusively in the semiconductor substrate.Finally, it is known, for example from the publication U.S. Pat. No. 2016 0 370 680 A1, which describes a process for structuring glass by means of laser ablation, while omitting wet chemical etching, that undesired optical diffraction (diffraction) of light can be avoided at glass edges processed by means of laser ablation, where circular indentations are produced per inserted laser pulse due to ablation, by setting the laser points with a high overlap, for example due to a high pulse frequency.Proceeding from this prior art, the object of the invention is to expand possible applications of the LIDE method.The invention has recognized the following: The wet chemical etching used in the LIDE method always begins on a substrate surface and proceeds from there into the depth (z direction) of the glass substrate. Depending on the selected process parameters (in particular material of the glass substrate, etching solution used and temperature), the etching radius r in the xy-plane (=substrate plane) can decrease more or less strongly along the z-direction (i.e. normal to the substrate plane), whereby (for example in the xz-plane) edge profiles can be achieved which have an inclination with respect to the z-axis. In this case, only slopes are always possible which correspond to a decreasing etching radius r with increasing depth z. However, the etching radius r on the substrate surface is always of the same size, since it depends only on the etching solution and the total etching time, and can therefore not be changed in a spatially resolved manner, which represents a central boundary condition of the LIDE method.By means of the respective etching radius r(z) which is generated in different xy-planes at different z-depths of the glass substrate, characteristic indentations can be formed in the side surfaces (in the direction of the xz- or yz-plane, respectively) which are always concave because the etching solution in a specific xy-plane isotropically etches and thus forms a convex etching front. This produces protruding glass ribs in these wet-chemical side surfaces which have been etched free, which protrude between the respective indentations and which, like the indentations, run along the z-direction. Depending on the selected process parameters, not only can there be an inclination of the bulges in the y-direction (e.g. in the case of a structure running in the x-direction), but also in the x-direction (for instance at the tip of such a structure).It has also been observed that the ribs, which actually would have to be purely geometrically sharp-edged, round with increasing etching duration, which seems to be caused by chemical processes in the micro-range. The ribs / bulges show a distance L x, which corresponds to the pulse distance p, from those laser points which are causative of the formation of the respective bulge. Since the ribs / protrusions appear similar to the ribs on the outside of a shell of mussels, these structures can be referred to as "sidewall scaling".With these in mind, in order to achieve the above object, the invention provides, in a mechanical microstructure, the features of claim 1.In particular, in order to achieve the object, it is thus provided according to the invention in a mechanical microstructure of the type mentioned at the beginning that, in order to produce the microstructure, laser pulses have / are placed on two opposing (imaginary or else real) tool paths in a deflection region of the microstructure (i.e. where the bending structure can move in the substrate plane or out of the substrate plane or where the micromechanical finger can move relative to the substrate), said tool paths having a respective maximum spacing r perpendicular to an (outer) contour (in particular to concave indentations in the contour) along a direction of extension of the microstructure. This distance r corresponds in this case precisely to an etching radius r of a wet chemical etching step which is / has been used for exposing the microstructure, wherein the etching radius r lies in a substrate plane of the glass substrate. In such an approach, the microstructure is thus configured monolithically (i.e. overall) as part of the glass substrate.In this case, it can be provided, as stated in claim 2, that the laser pulses have been placed (or are placed) during the production of the microstructure in such a way that a respective spatial phase position φ(x) of respective laser pulse pairs is set homogeneously along a direction of extension of the microstructure within said deflection range. The homogeneous adjustment of the phase position should be realized at least in sections in order to achieve a significant technical effect; preferably, the phase position can be adjusted homogeneously along the entire deflection range.To achieve the object, it can furthermore be provided that, during the production of the microstructure (preferably all), those laser pulses (or laser points) which define an outer contour of the microstructure are / have been placed on respective continuous (that is to say, for example, rectilinear or curved) tool paths, at least in the said deflection region of the microstructure. In this case, each of the tool paths has a maximum distance from the contour which corresponds precisely to an etching radius r of a wet chemical etching step which was / is used for exposing the microstructure (from the glass substrate). The laser pulses on the tool path thus have a distance r from associated concave indentations in the contour. In this case, the laser pulses can preferably be / are placed on the respective tool path at a constant pulse interval p, at least in sections (for example by setting at least three adjacent laser pulses one after the other at the pulse interval p on the respective tool path). It is understood that, depending on the selected extent of sidewall scaling, the respective tool path will have a minimum distance of r-t y to the contour, with t y of the depth of the respective indentation in the side wall of the microstructure.A phase position φ(x) can be understood here in particular as the following spatial relationship which describes the positioning of the laser points or of the indentations (described above) produced therefrom: φ(x)=Δx / p'×360. Here, φ(x) stands for the spatial phase position at a specific x position along the extension direction of the microstructure, Δx is an offset between two mutually opposite laser points along the extension direction of the microstructure, and p' is an effective pulse distance on a central axis of the microstructure (in the case of a rectilinear microstructure, p' is equal to the geometric pulse distance p between two laser points directly adjacent on a tool path). This will be explained in more detail with reference to the drawings.A homogeneous phase position can be achieved, for example, if the phase position φ(x) fluctuates by less than + / - 60°, particularly preferably by less than + / - 30°, along the direction of extension of the microstructure. In this case, the mean phase angle (or also mean phase angle φ or mean phase delay φ) can be chosen differently (for example φ=0° or φ=180°).In other words, according to the invention, it can thus be provided that the laser pulses and the etching radii resulting therefrom (which result when the microstructure is exposed in the glass substrate in a wet chemical manner) have / are placed uniformly along two mutually opposite side surfaces (or side walls) of the microstructure in such a way that respectively mutually opposite laser point pairs (and the indentations resulting therefrom) always show a homogeneous (i.e. for example approximately constant) offset Δx. The offset Δx can fluctuate somewhat here, for example due to the process or due to the geometry of the microstructure, but should always be selected such that a homogeneous phase position φ(x) results. For example, the variation of Δx may be so small that the phase position φ(x) in the deflection range of the microstructure changes by less than + / - 60°, particularly preferably by less than + / - 30°.According to claim 1, the invention further proposes adjusting the sidewall scaling of the microstructure in a targeted manner in order to adjust the mechanical properties in a desired manner (high homogeneity or else targeted non-homogeneity). Therefore, according to the invention, in order to achieve the object, it is provided in a mechanical microstructure of the type mentioned at the beginning that, in order to produce the microstructure, laser pulses have / are placed in a deflection region of the microstructure on two mutually opposite tool paths which have a respective maximum spacing r perpendicular to an (outer) contour (in particular to concave indentations in the contour) along a direction of extension of the microstructure which corresponds to said etching radius r of the wet chemical etching step. Since this etching radius r lies in the substrate plane of the glass substrate as mentioned, the contour after the wet chemical exposure shows lateral concave indentations, each of which shows a curvature with the etching radius r and which are bounded by respective convex ribs. In order now to improve homogeneity of the mechanical properties of the microstructure or else in order to generate in a targeted manner an inhomogeneity of the mechanical properties of the microstructure, it is proposed according to the invention that the laser pulses have / are placed in such a way that the characteristic of a sidewall scaling of the microstructure is set in a targeted manner, to be precise at least in sections, but preferably along the entire deflection region.The sidewall scaling can be defined, for example, as a ratio t y / r of the local etching radius r and a respective lateral depth t y of the respective indentation. Targeted setting can be understood here in particular to mean that the sidewall scaling is either weak throughout the entire deflection range or strongly pronounced throughout the entire deflection range.In other words, the extent of the sidewall scaling, in particular the size of the respective lateral depth t y, can thus be adjusted in a spatially resolved manner in a targeted manner along the course direction by suitable placement of the laser pulses on the substrate plane. For example, it can be provided that, in order to achieve consistently weak sidewall scaling, for the respective lateral depth t y at least in sections, but preferably along the entire deflection range, the following applies: t y / r<0.1, preferably t y / r<0.05, with r the etching radius. In this case, the mechanical properties of the micro / bending structure will be very homogeneous. It can furthermore be provided that the lateral depth t y fluctuates by less than 40% in the deflection range, in particular by less than 20% or even by less than 10%.If, on the other hand, a targeted non-homogeneity is to be generated, which can be utilized, for example, by actuator or sensor means, it can be provided that for the respective lateral depth t y at least in sections, but preferably along the entire deflection range, the following applies: t y / r>0.1, preferably t y / r>0.2, whereby a strongly pronounced sidewall scaling (in relation to the etching radius r) can be achieved. In this case, the mechanical properties of the micro / bending structure will be inhomogeneous. Under certain circumstances, in such configurations, the lateral depth t y in the deflection region can fluctuate by 50%, or else the fluctuation is small, with the result that very pronounced sidewall scaling then results homogeneously, but this likewise leads to the desired non-homogeneity.This invention(s) can / can be used in particular to form glass-based MEMS (microelectromechanical systems), i.e. GMEMS, which have excellent mechanical properties. As a first example, a cantilever with a width of less than 50 μm or even less than 20 μm may be mentioned. With such small widths, there is a high risk of spring breakage. By forming a homogeneous phase position of, for example, φ(x)=180°+ / -30° or even φ(x)=180°+ / -15° and / or an only slightly pronounced and homogeneously set sidewall scaling, the breaking strength of the cantilever can be substantially improved. As a result, such a spring structure can be reliably used in a GMS. The placement of the laser spots on continuous tool paths which have the said maximum distance of r from the contour of the bending beam ensures that very thin bending beams can be produced reproducibly. This likewise results in advantages for the actuator system / sensor system which uses such a bending beam.Unlike in classical MEMS based on silicon as substrate material, glass is used in GMEMS in order to form the micromechanical structures, more precisely the micromechanical microstructure mentioned. Unlike silicon, glass is not a semiconductor but an insulator. However, the electrical functionality of a GMEMS can be achieved by adding electrically conductive layers, for example metallic thin films on the glass.The invention thus proposes not simply allowing the phase position to be random, but rather specifically setting and making it homogeneous in certain regions of a microstructure, namely in the region of relevant deflection of the microstructure (deflection region), for example either with a weakly pronounced or strongly pronounced phase distortion. The phase delay can be considered here as being at a maximum for a phase of φ=180° and at a minimum for a phase of φ=0°. An advantage of such a configuration is that the mechanical properties of the microstructure can be better controlled, as will be explained in detail below.For the production of the microstructure, it can be provided, for example, within the scope of the LIDE method that a series of laser pulses is / have been placed on a laser line for this purpose in order to introduce a modification into the glass substrate with the aid of laser radiation. The regions of the glass substrate which are / have been modified in this way by means of the laser radiation can then be etched free in a subsequent wet chemical etching step (in particular the previously described).The microstructure can have microscopic dimensions, for example with respect to a width (in the substrate plane) and / or height (normal to the substrate plane) of the microstructure. For example, the width / height may be in the sub-mm range and may be about less than 100 μm, less than 50 μm or even less than 20 μm (e.g. in the case of very narrow cantilevers). The length of the microstructure, on the other hand, can range from the sub-mm range over the mm range to even the cm range, since large GMS structures in particular can be formed by means of LIDE.The microstructure thus produced can thus have at least one microscopic dimension, for example the length and / or width and / or height (transverse to the substrate plane) of the microstructure. This is because the accuracy in the positioning of the laser pulses can be a few micrometers, so that very fine microstructures can be exposed wet-chemically, wherein here too the high anisotropy that can be achieved using the LIDE method is beneficial. A microstructure configured according to the invention can exhibit, for example, an aspect ratio (height: width) of at least 10:1, of at least 20:1, or even of at least 50:1.The microstructure can be designed, for example, as a cantilevered bending beam (cantilever beam), with a free-standing end. However, it can also be anchored, preferably monolithically, on both sides in the glass substrate, for example.Depending on the application, the microstructure can be designed both for in-plane deflections (in the xy-plane, which corresponds to the substrate surface) and / or for out-of-plane deflections (then in the z-direction). In addition to such vibration modes, torsional vibrations of the microstructure can also be excited, additionally or alternatively. For all such applications, the invention offers technical advantages with respect to the mechanical properties of the glass microstructure, in particular with respect to breaking strength, homogeneity of the rigidity and reduction of the transverse sensitivity.A microstructure in the sense of the invention can thus be designed as a micromechanical bending element, in particular as a micromechanical spring element, that is to say for example as a bending beam clamped on one side or two sides, but also for example as a membrane, as a torsion beam or for example as a movable finger of a comb structure, for example of a micromechanical actuator or sensor. The mobility of the finger can be achieved, for example, by the finger being suspended from a micromechanical spring element (this can be designed in particular according to the invention).It should be noted that each laser pulse can be assigned an associated laser point on the surface of the glass substrate, which corresponds to the center of the point of impingement of the laser pulse on the glass substrate surface. The mentioned tool paths correspond to those paths along which a laser head emitting the laser pulses is guided, wherein the laser head is typically guided at a constant z-distance from the substrate surface.The homogeneous configuration of the phase position φ(x) of the microstructure (with respect to a contour of the microstructure) can achieve, in particular, that (i) a spring stiffness of the microstructure is minimized and / or that (ii) a homogeneity of the mechanical properties of the microstructure is set in a targeted manner (that is to say in particular minimized or maximized) and / or that (iii) a transverse sensitivity of the microstructure to an interference variable is set in a targeted manner (that is to say in particular minimized or maximized) and / or that (iv) a fracture strength of the microstructure is increased. In other words, numerous mechanical properties of the microstructure can be controlled and optimized by the targeted control of the phase position φ(x).It is understood that microstructures as described herein and the associated production methods can thus be used or used to achieve the above-mentioned four technical effects (i)-(iv). A low spring stiffness / high homogeneity / low transverse sensitivity / high breaking strength can be achieved here by a large phase distortion and / or a low degree of sidewall scaling. Conversely, a low phase distortion, especially with a very small width of the microstructure, and / or a strongly pronounced sidewall scaling can result in a comparatively high spring stiffness / low or poor homogeneity / high transverse sensitivity / low breaking strength of the microstructure.In addition to the features described above, the object can also be achieved by means of a microstructure according to claim 2. Thus, in order to achieve the object, it can be provided in particular that a respective spatial phase position φ(x) of respective laser pulse pairs along a course direction of the microstructure within the deflection range φ(x)=180° + / - 60°, preferably φ(x)=180° + / - 30°. In such embodiments, there is therefore a large spatial phase distortion φ. In such a configuration, it is also preferable if the following applies for a maximum width B of the microstructure within the entire deflection range: B<200 μm, in particular B <100 μm or even B<50 μm or B<20 μm. This is because microstructures can be produced or obtained by such features, which exhibit a very good mechanical response and which, despite their microscopic size, have a high breaking strength.Since both the pulse interval p and the etching radius r are technically limited and from the process cost perspective, softer and more homogeneous micromechanical springs can be produced with higher reproducibility with a phase position of approximately 180°. Thus, lower forces are required for the deflection, less space is required or the fill factor is increased and the lower peaks of the mechanical stress during the deflection result in a higher breaking strength.Such a phase position can thus lead, in particular in conjunction with a weakly pronounced sidewall scaling, to an excellent homogeneity of the mechanical properties of the microstructure, which is relevant, for example, for applications of micro-actuator system or micro-sensor system. For example, certain desired characteristics of the micro-actuator system can be adjusted in a targeted manner in this way, i.e. the electrostatic response behavior of the microstructure can be influenced in a favorable manner. This allows an improved actuator system and / or sensor system of a GMEMS to be achieved in comparison with microstructures in which the sidewall scaling and / or the phase is not adjusted in a targeted manner.In order to realize such advantages, it can furthermore be provided that, in order to achieve a weakly pronounced sidewall scaling, the laser pulses are / have been set and the microstructure has / is etched free in such a way that the following applies to a ratio of an average pulse spacing p between adjacent laser pulses on one of the two tool paths (i.e. placed on the same tool path) and the etching radius r, preferably in the entire deflection range: p<r. It can even apply: p<r / 2.In the extreme case, with semicircular indentations, the length L x of a respective indentation in the side wall of the microstructure would be: L x= 2 r=p. The following would thus be valid: p / r=2:1 or p=D=2r, where D is the etching diameter at the substrate surface.In general and especially in such embodiments, it is also preferable if directly adjacent ones of the laser pulses have a minimum pulse spacing of at least 3.0 μm or even at least 5.0 μm (on the respective tool path). This is because optical shading effects can be avoided and a homogeneous etching result can be achieved, which ensures that the extent of sidewall scaling becomes reproducible and can therefore be adjusted in a targeted manner during the production of the microstructure. On the other hand, it is advantageous for low sidewall scaling if the pulse interval p remains below 10.0 μm, in particular below 7.0 μm, at least in the deflection range of the microstructure.As already mentioned, the contour of the microstructure (in the region of the side walls) therefore typically has lateral concave indentations after the wet chemical exposure. These indentations each show a curvature with the etching radius r and are bounded by respective convex ribs.It can now be provided that the following applies to a ratio of the local etching radius r and a lateral depth t y of the respective indentations: t y / r<0.1. t y / r<0.05 or even t y / r<0.03 can preferably apply. In this case, the depth t y can be measured transversely to the direction of extension of the microstructure.Additionally or alternatively, however, with respect to these features just described, it is also possible for a ratio of the maximum width B of the microstructure transversely with respect to the direction of extension and the lateral depth t y of the respective indentation to apply: t y / B≤0.1, in particular t y / B≤0.05. Such embodiments also define very weakly pronounced sidewall scaling.Such indentations delimited by (more or less strongly pronounced and / or more or less strongly rounded) ribs can, as mentioned, be subsumed under the term "sidewall scaling", since the ribs structure the side surfaces of the etched-free microstructure, but on a microscopic scale, in a similar manner to a shell shell of mussel. The two configurations described above thus result in particularly flat / less pronounced sidewall scaling, as a result of which a particularly small variation in the width of the microstructure and hence a high homogeneity of the rigidity are achieved. In this case, it should be taken into account that the surface moment of inertia in the case of deflections in the substrate plane depends cubically on the width (in the case of out-of-plane deflections, on the other hand, the surface moment of inertia increases linearly with the width and cubically with the height / thickness of the microstructure) and, therefore, in the case of pronounced sidewall scaling, the local surface moment of inertia can fluctuate considerably along the longitudinal axis of the microstructure. Adjacent ones of the ribs can have a distance L x from one another which corresponds precisely to the pulse distance p of the associated laser pulses.The ribs mentioned can typically extend in the z-direction, i.e. normal to the substrate plane. The same also applies to the course of the indentations themselves. In this case, the ribs and the indentations can form an inclination with respect to the z-axis (in particular at a taper angle φ), depending on the selected degree of anisotropy of the wet chemical etching process used.Each of the indentations in the respective side wall of the microstructure can in principle be assigned to an associated laser pulse which was at a distance r from the contour (=outer contour line in the substrate surface / on the upper side of the microstructure). The associated laser pulse or laser point (=injection point of the laser pulse on the glass substrate surface) is the cause of the formation of this indentation, because the etching front proceeds isotropically from the laser point.A configuration of the microstructure with low sidewall scaling and a comparatively large phase distortion φ(x) may be advantageous, for example in order to enable a particularly high breaking strength and thus particularly large deflections of the microstructure. This is because, in the case of small-scale scaling, local peaks of the mechanical load are avoided, in particular, because the surface moment of inertia is designed to be more homogeneous. In the case of sensory applications, on the other hand, the sensitivity with which the microstructure can detect mechanical oscillations can be increased (for the same reasons).Particularly weak sidewall scaling will entail advantages for the homogeneity of the mechanical properties of a microstructure, in particular, if the width thereof is comparatively small, which then leads to a correspondingly high ratio of t y / B, given t y. This is therefore relevant in particular when the maximum width B of the microstructure (transverse to the direction of extension) falls below 100 μm or even 50 μm.Another way of describing the phase delay between mutually opposite laser pulses or laser points is to specify a step angle α that a respective laser pulse pair forms in the deflection region of the microstructure 1 with respect to the direction of extension. The step angle α can be, for example, more than 2.5°, in particular more than 5° or even more than 7° or even more than 9°, depending on the width of the microstructure. In this case, the following can apply in particular to the step angle α: α=arctan(Δx / Dy), where Δx is the offset of the laser pulses forming the laser pulse pair with respect to one another along the course direction, and Dy is the distance of the two mutually opposite laser pulses (or of the associated tool paths) transversely with respect to the course direction. In this case, the step angle α increases with decreasing width B and increasing offset Δx / increasing phase distortion φ(x).If the offset between the laser points is, for example, Δx=p / 2=5 μm at a pulse interval of p=10 μm and if φ(x)=Δx / p'×3600°=180° and an etching diameter D=2r=20 μm is also used, then if the spring width of B=10 μm, the distance D y between the tool paths can be, for example, D y≈30 μm. Accordingly, a step angle of α≈arctan(Δx / Dy)=arctan(5 / 30)=9.5° is then obtained.A further embodiment provides that for a ratio of a (in particular minimum or maximum) pulse spacing p between two (directly) adjacent laser pulses on one of the two tool paths and a maximum width B of the microstructure transversely to the direction of extension, the following applies: p / B≤1.0, preferably p / B≤0.75 or even p / B≤0.5. In the case of high aspect ratios (e.g. t / B≥40) and / or very small spring widths (B≤20 μm), the microstructure may even be provided: p / B<0.4, preferably p / B≤0.3. The pulse spacing p used can be read from the spacing L x between two adjacent indentations in the side wall of the microstructure which were produced by the wet chemical etching.In such embodiments, the maximum width of the microstructure may be less than 50 μm, in particular less than 20 μm. For example, a ratio of p / B=0.5 can be established for a minimum pulse interval of p min= 5 μm and a maximum / nominal width of 10 μm of a microstructure used as a micromechanical spring.As a technical effect, it must be taken into account here that the smaller the pulse interval p is selected and thus the smaller p / B is, the weaker the micro-scaling will be pronounced and the more homogeneous the mechanical properties of the microstructure will therefore be.Alternatively or additionally to all the features described above, the object can also be achieved by means of a microstructure according to independent claim 7. Thus, in order to achieve the object, it can be provided in particular that a respective spatial phase position φ(x) of respective laser pulse pairs along a course direction of the microstructure within the deflection range of the microstructure is φ=0° + / - 60°, preferably φ=0° + / - 30°. In such a configuration, it can furthermore be provided that the following applies for a maximum width B of the microstructure within the entire deflection range: B <100 μm, in particular B<50 μm or even B<20 μm.Such a phase position with only a very small phase delay φ can lead, especially in conjunction with a strongly pronounced sidewall scaling, to a comparatively large non-homogeneity of the mechanical properties of the microstructure. Even if this seems unfavourable at first glance, advantageous effects can arise from such an non-homogeneity, as will be explained in detail below. For example, certain desired characteristics of the micro-actuator system can be adjusted in a targeted manner in this way, i.e. the electrostatic response behavior of the microstructure can be influenced in a favorable manner. This allows an improved or qualitatively different actuator system to be achieved in comparison with previously known microstructures, in particular those which do not exhibit any sidewall scaling and / or no such spatial phase distribution.Therefore, in particular with a very low homogeneous phase delay φ, in order to achieve a strongly pronounced sidewall scaling, the laser pulses can also be set and the microstructure can be etched free in such a way that the following applies for a ratio of an average pulse spacing p between adjacent laser pulses on one of the two tool paths and the etching radius r, preferably in the entire deflection range: p>r or even p >1.2r.In the extreme case, in the case of semicircular indentations (=maximal pronounced sidewall scaling), the length L x of an indentation in the direction of extension would be applicable: L x= 2 r=D=p, i.e. the following would then be applicable: p=2r (p is then maximally large). If the pulse interval p is reduced starting from this maximum, the extent of sidewall scaling decreases continuously. However, for values p >1.0 r or even p >1.20 r, sidewall scaling will still be comparatively strongly pronounced. Such a strongly pronounced sidewall scaling can lead, especially in conjunction with the phase position around 0° explained above, to interesting mechanical properties of the microstructure, which can be utilized technically, in particular for novel micro actuator system or micro sensor system.A strongly pronounced sidewall scaling can alternatively also be achieved by the following design or process parameters. Thus, it can be provided that the contour of the microstructure (as already explained) exhibits lateral concave indentations, which each exhibit a curvature with the etching radius r and which are bounded by respective convex ribs. Furthermore, the following can then apply to a ratio of the etching radius r and a lateral depth t y of the respective indentations: t y / r>0.1, in particular t y / r>0.2 or even t y / r>0.3 (cf. Tables 4 and 5).In order to achieve a low phase delay, it can also (additionally or alternatively) be provided that the previously described step angle α is comparatively small. Thus, the step angle α can be, for example, at most 4.0°, in particular at most 3.0°, preferably at most 2.0°. At such low stepping angles, which can be achieved by appropriate placement of the laser pulses (used for etching the microstructure free), a low phase distortion φ(x) will result for a given etching radius r, which in turn is largely predefined for a specific substrate thickness and selected materials (glass substrate, etching solution).According to a further embodiment, it can furthermore be provided that a ratio of an, in particular minimum or maximum, pulse spacing p between two adjacent laser pulses on one of the two tool paths and a maximum width B of the microstructure transversely to the direction of extension applies: p / B≥0.5, preferably p / B≥0.75 or p / B≥1.0 or even p / B≥1.5. As a technical effect, it must be taken into account here that the greater the pulse interval p is selected and thus the greater p / B, the stronger the micro-scaling will be pronounced and the more inhomogeneous the mechanical properties of the microstructure will therefore be. This non-homogeneity may be of technical interest for novel actuator and sensor mechanisms. For example, a ratio of p / B=1.0 can be established for a minimum pulse interval p of at least 10 μm and a maximum / nominal width B of 10 μm of a microstructure used as a spring.The invention can be advantageously used, for example, in micromechanical microstructures which are characterized in that the mutually opposite tool paths run approximately or strictly parallel to one another. However, refinements of microstructures according to the invention are also possible if the mutually opposite tool paths enclose an angle or, for example, follow a respective curve. In the first two cases, the direction of extension of the microstructure can follow a straight line; in the latter case, on the other hand, it can follow a curve. In such cases, the phase position may also change locally. By suitably setting the laser points and selecting the pulse interval and the etching radius r (which is essentially determined by the substrate material, the etching time and the etching liquid used), however, it is also possible in such cases to set or form homogeneous phase positions, at least in sections, along the direction of extension of the microstructure--either with a large or a low phase position, depending on the task position.In order to design the processing / production of the microstructure in a reproducible manner, it can be provided in particular that a minimum pulse spacing of 3 μm and / or a maximum pulse spacing of 15 μm, in particular of 10 μm, was observed during the production of the microstructure in the deflection region. The fact that this condition has been met can be read off, for example, from the characteristic of sidewall scaling, since-as already mentioned-the distances of the ribs of sidewall scaling correspond precisely to the pulse distance of the associated laser pulses which are causative of the respective side wall etching which the ribs produced.For example, it may be expedient, especially if only a small sidewall scaling is to be formed, to choose the pulse interval in the range of 2-8 μm, preferably in the range of 3-5 μm. Such values are possible, for example, with substrate thicknesses between 100 μm and 500 μm. If, on the other hand, the sidewall scaling should or may be more pronounced, it may be expedient to choose the pulse interval such that the following applies: p≥7 μm, in particular p≥10 μm.The invention can be used particularly advantageously in a microelectromechanical system. This can have at least one microstructure according to the invention or a multiplicity of microstructures according to the invention, for example configured as fingers of a comb actuator or comb sensor.The invention furthermore proposes a specific application or use of a microstructure according to the invention or of such microelectromechanical system. Thus, to achieve the object, the use of a micromechanical microstructure made of glass produced by means of laser induced deep etching (LIDE) is proposed, in particular, as part of a micromechanical actuator and / or as part of a micromechanical sensor and / or as part of a micromechanical carrier structure, preferably using electrostatic actuation or a capacitive sensor principle. In this case, the microstructure can be configured as explained above, in particular according to one of Claims 1 to 7, that is to say in particular with a comparatively large phase position and / or with controlled, in particular low-level, sidewall scaling. In such a use, the specific setting of the phase position φ(x) and / or the specific (preferably scwache) form of a sidewall scaling of the microstructure can be used to improve the homogeneity of the mechanical properties of the microstructure, as has already been explained in detail above. The microstructures can form spring elements of the actuator system / sensor system or, for example, the fingers of a micromechanical comb structure. This is relevant, for example, both for linear and rotational micro-actuator systems.In addition, however, it is also possible to use a micromechanical microstructure produced by means of LIDE as part of a micromechanical actuator and / or as part of a micromechanical sensor, preferably using electrostatic actuation or a capacitive sensor principle, and in the process to set the phase position φ(x) and / or the characteristic of a sidewall scaling of the microstructure in a targeted manner (wherein a strongly pronounced sidewall scaling can preferably be used) in order to generate an non-homogeneity of the mechanical properties of the microstructure which can be used or is utilized, respectively, by sensor or actuator. Such a glass microstructure with preferably low phase distortion and / or with pronounced sidewall scaling can be used in particular for realizing a micromechanical stepper motor. In this case, the step size of the motor can just correspond to the (local) period of sidewall scaling.Finally, in order to achieve the object mentioned at the beginning, a method for producing a micromechanical microstructure from glass by means of LIDE is also proposed. In this method, laser pulses are placed in a deflection region of the microstructure on two mutually opposite tool paths, as already described above in greater detail with reference to the microstructure according to the invention. As mentioned, the laser pulses or associated laser points (already in the layout) have a respective distance r from a contour (more precisely from respective associated concave indentations) of the microstructure, which corresponds to an etching radius r of a later wet chemical etching step. After the wet chemical exposure, the contour shows lateral concave indentations, each of which shows a curvature with the etching radius r and which are bounded by respective convex ribs.The etching step is thus used to expose the microstructure in the glass substrate and thus to enable mobility of the microstructure, either in the plane of the glass substrate or normally thereto. The method can now be characterized in that the laser pulses are set on the respective laser line in such a way that (i) a homogeneous distribution of the spatial phase position φ(x) and / or (ii) a homogeneous extent of sidewall scaling (which can be applied and defined as described above) along a direction of extension of the microstructure results, which has already been explained in detail above with reference to the microstructure. In this case, the laser pulses / laser points can therefore be set such that a microstructure as described above, in particular according to one of Claims 1 to 14, is wet-chemically etched free.Here, homogeneous distribution of the phase position can be understood in particular to mean that (in particular independently of the profile of the microstructure) the phase position φ(x) does not fluctuate by more than + / - 60°, preferably less than + / - 30°, about an average phase value φ 0 in the entire deflection range. By homogeneous setting of sidewall scaling, however, it can be understood in particular that, for example, the mentioned lateral depth t y fluctuates in the entire deflection range by no more than + / - 30%, preferably less than + / - 20%, or even by no more than + / - 10% around an average lateral depth t 0. Depending on the desired property of the microstructure, the ratio t 0 / r can be greater or less high.The invention will now be described in more detail with reference to exemplary embodiments, but is not limited to these exemplary embodiments. Further embodiments of the invention may be obtained from the following description of a preferred embodiment in conjunction with the general description, the claims and the drawings. In the following description of various embodiments of the invention, elements which correspond in function are given corresponding reference numerals even if the design or shape is different.It shows: FIG. 1 shows a first example of a micromechanical microstructure in glass designed according to the present invention, FIG. 2 shows a further example of a microstructure according to the invention, FIG. 3 shows a further example of a microstructure according to the invention, FIG. 4 shows a detailed and schematic view of the outer contour of a subsection of a microstructure configured according to the invention, FIG. 5 shows a graph showing the width B(x) of a bending beam configured according to the invention as a function of the x position for three cases of differently configured phase positions φ(x), FIG. 6 shows a further schematic illustration of a subsection of a microstructure according to the invention, FIG. 7 shows an example of a microstructure according to the invention, which shows a waveform in the x-substrate plane, FIG. 8 shows a further schematic top view, similar to FIGS. 1-3, of a microstructure according to the invention, wherein numerous design or process parameters are illustrated, FIG. 9 shows a further example of a microstructure according to the invention, in which the outer contour lines run at an angle to one another, FIG. 10 is a cross-sectional view of a medium taper angle microstructure according to the invention, FIG. 11 shows a cross-sectional view of a microstructure according to the invention with a larger taper angle, FIG. 12 shows a further cross-sectional view of a microstructure according to the invention with an extremely low taper angle, FIG. 13 shows a scanning electron microscope (SEM) image of a micromechanical comb structure having microstructures in the form of fingers, which are designed according to the invention, and FIG. 14 shows a scanning electron microscope (SEM) image of a microstructure configured according to the invention in the form of a thin cantilever.FIG. 1 schematically shows a micromechanical microstructure 1 in the form of a cantilever 16 which is exposed with the aid of the LIDE (laser induced deep etching) method and which has been exposed from a glass substrate 3 in the form of a glass wafer by means of wet chemical etching. The view of FIG. 1 is a view from above onto the xy plane of the glass substrate 3, which has a specific substrate thickness t glas in the z direction. As can be seen, the cantilever 16 is connected on one side to the "bulk" of the glass substrate 3 and forms a flexure joint 17 or a one-sided mechanical suspension there. The cantilever 16 can in this case be deflected out of the plane in principle in the xy-plane but also in the z-direction.By means of the LIDE (laser induced deep etching) method, it is possible to cut or expose fine glass pieces from a glass substrate 3. Similar to a saw blade, a contour 6 can be traversed with the aid of a laser, which contour describes the outer boundary of the microstructure 1 to be exposed. For this purpose, it is proposed according to the invention that a laser head which emits the pulsed laser beam is moved on an associated tool path 5 a, 5 bwhich follows the contour 6 at a specific distance (cf. FIG. 3 ). However, since the laser is pulsed, the glass substrate 3 is not continuously illuminated by the laser beam, but individual laser pulses 4 are set at specific xy coordinates on the surface of the glass substrate 3 as laser spots 4. In this case, the laser spots 4 can have a constant geometric pulse interval p (measured in μm in the substrate plane) and / or all lie on the said tool path 5 a, 5 b. The block arrows in FIG. 3 are intended to indicate in which sequence the tool paths 5 are traversed and the laser spots 4 are set (cf. also FIG. 6 ).If, for example, an elongate slot is to be applied in the glass substrate 3, a certain number of laser pulses 4 are placed along a tool path 5, each at the pulse interval p, wherein the glass substrate 3 is typically modified over the entire thickness with each laser pulse 5. In the subsequent wet chemical etching process, the etching solution cracks from the surface in the z direction into the substrate 3, wherein the etching speed in the xy plane is isotropic, so that a circular-disk-shaped etching profile 7 with rotational symmetry around a respective laser point 4 results on the surface (cf. the circles in FIGS. 4 and 6 to 8). This has the consequence that the finally freely etched contour 6 of the microstructure 1 shows a distance r (=etch radius 27) from the center of the original laser point 4 (cf. FIG. 3 or 6 ). In other words, the freely etched contour line 6 on the surface of the glass substrate 3 shows a maximum distance r from the tool path 5 (projected onto the substrate plane) on which the laser pulses 4 have been placed. In other words, each of the laser pulses 4 on the tool path 5 has a distance r from the respective associated indentation 8, which arises on account of the etching radius 27 starting from the respective laser pulse 4.On account of the etching radii r, concave indentations 8 are thus formed in the respective side wall 13 of the microstructure 1, each of which indentations has a curvature with the etching radius r 27 and which indentations are bounded by respective convex ribs 9, wherein these ribs 9 however also the indentations 8 run along the z-direction (cf. FIGS. 1-3 and 4 and 6-9). These structures in the respective side wall 13 that are produced during the wet chemical exposure of the microstructure 1 are referred to as sidewall scaling, since the indentations 8 or the ribs 9 lying therebetween form a structure similar to that on the inner side of a shell shell.Depending on the selected process parameters and thus the degree of anisotropy of the wet chemical etching, the etching radius 27 rcan decrease more or less strongly in the xy plane along the z direction (i.e. normal to the substrate plane), whereby (for example in the xz plane) profiles of the side walls 13 of the microstructure 1 can be achieved which have an inclination or form a taper angle φ with respect to the z axis, as illustrated in FIGS. 10-12. On the substrate surface, however, the etching radius 27r is always the same, starting from each laser point 4. Furthermore, only slopes are always possible which correspond to a decreasing etching radius 27 rwith increasing depth z. This results from the fact that the wet chemical etching always begins on the substrate surface and proceeds from there into the substrate depth. However, it is possible to perform this process either on one side (FIG. 12 ) or on both sides (see:. FIGS. 10 and 11 ) are to be started from both substrate surfaces, so that correspondingly symmetrical slopes are then obtained, each of which tapers in the direction of a plane 21 arranged centrally (in the z direction) (which lies parallel to the xy plane).As is indicated in FIG. 11, which shows a cross section through a microstructure 1 according to the invention (wherein the direction of extension 2 of the microstructure 1 runs in the direction of view of the drawing), an individual laser spot 4 can already be sufficient to define a slot having a width 2 rbetween a microstructure 1 and the substrate 3, wherein the etching solution then forms an etching radius 27 ron both sides on the surface of the glass substrate 3 starting from the laser spot 4 (for example in the positive and negative y-direction as in FIG. 11 ). In this case, the maximum width B 15 of the microstructure 1 (measured transversely to the direction of extension 2, i.e. in the y direction in FIG. 11 ) measured on the surface of the glass substrate 3 can deviate considerably from the width B M, which the microstructure 1 shows in the illustrated central plane 21 of the substrate 3, depending on the taper angle φ selected.As FIG. 12 illustrates, however, laser spots 4 can also be placed next to one another at a very narrow pulse interval p, so that the resulting etching radii r then overlap (cf. also FIG. 8 in this respect). If the anisotropy of the laser-induced wet chemical etching is selected to be very high, nearly vertical side walls 13 can be defined, as shown in FIG. 12.FIG. 8 illustrates in detail how the microstructure 1 of FIG. 3 has been produced. As can be seen from the circles which each illustrate the circular-disk-shaped etching profile 7 with the etching diameter D=2r, a whole series of laser pulses 4 were placed on two mutually opposite tool paths 5 aand 5 bin the deflection region 12 of the microstructure 1. Since the etching front 7 spreads isotropically in the xy substrate plane, the laser pulses 4 each have a distance r from the final outer contour 6 of the microstructure 1, which corresponds precisely to the etching radius 27 rof the wet chemical etching step used for exposing the microstructure 1. As FIG. 3 shows, two laser pulses 4 each, which lie on the mutually opposite tool paths 5 aand 5 b, can be combined to form a laser pulse pair 18. As FIGS. 1-3 and 8 show, the two laser pulses 4 of a respective laser pulse pair 18 can show-in relation to the direction of extension 2 of the microstructure 1 which corresponds to the x-axis in these figures-an offset Δx which can be between Δx=0 and Δx=p / 2, for example, when using a constant pulse spacing p.Depending on the extent of this offset Δx, a spatial phase position φ(x) or a spatial phase delay φ(x) results between the respective laser points 4 of a laser point pair 18. In the example of FIG. 1, the offset Δx=0 and thus the laser points 4 of the respective laser point pair 18 are arranged there just in phase (φ=0°) with respect to the course direction 2. in the example of FIG. 3, on the other hand, the phase difference is at most (φ=180°), because the offset Δx is there Δx=p / 2, with p the pulse interval, i.e. the interval between two directly adjacent laser points which are placed on the same tool path (e.g. 5 b) - cf. FIG. 8 in this respect.The ratio p / r of the pulse interval p and the etching radius 27 r, on the other hand, determines how strongly the indentations 8 of the sidewall scaling are formed. The distance between the ribs 9 along the x-axis L X corresponds in this case precisely to the pulse distance L x= p-cf. FIG. 8 In addition, a lateral depth t y14 can be determined for each indentation 9, namely measured transversely to the direction of extension 2, that is to say in the y-direction in FIG. 8.It can be seen in FIGS. 1-3 for example that there-in each case independently of the selected phase position-the sidewall scaling along the outer contour 6 is only weakly pronounced in the deflection region 12 of the microstructure 1, which can be seen from the small ratio t y / r. This also applies to the microstructure shown in FIG. 7, because even there, despite a curved profile, the laser pulses 4 are set such that the sidewall scaling is entirely weakly pronounced along the entire deflection region 12, with the result that this microstructure will exhibit homogeneous mechanical properties.In FIG. 4 or approximately in FIG. 9, however, sidewall scaling (in each case) is formed to be substantially stronger, that is to say the lateral depth t y14 is selected to be greater there in relation to the etching radius r. Such a predictive sidewall scaling alone already leads to an non-uniformity of the mechanical properties of the bending structure 1, because then, for example, the width B along the x-axis fluctuates more strongly along the extension direction x of the microstructure 1, as can be seen easily with reference to FIG. 5. This variation and thus the non-uniformity will be the higher for a given extent of sidewall scaling, the smaller the phase position is selected (compare for example the profile of the average width B at 0° and at 180° phase).In both cases of FIGS. 1-3 and 4+9, however, it can be seen that the extent of sidewall scaling in the entire deflection region 12 is set homogeneously in each case, since the respective variation of the lateral depth t y14 is selected to be very small, by suitable placement of the laser spots 4.It can thus be stated that the laser spots 4 do not follow a predefined grid in the approach according to the invention, but rather are defined or placed in a targeted manner on the basis of the outer contour 6 of the desired microstructure 1 (i.e. on the basis of design or geometry parameters of the microstructure 1), in order to achieve the desired phase position and / or the desired sidewall scaling. This distinguishes this process control from DEEP RIE (deep reactive ion etching), for example, as has long been used in the structuring of silicon, where the formation of ribs is only predefined by process parameters of dry etching, but is not specifically set / prebeked on the basis of a structure design.It is also illustrated in FIG. 8 that the two tool paths 5 aand 5 bhave a distance D y10 from one another. This distance and the selected offset Δx determine the step angle α that two laser points 4 of a respective pair of laser points 18 form with respect to the direction of progression 2, wherein α=arctan(Δx / D y). The spatial phase position φ(x), on the other hand, is determined to be φ=3604 Δx / p, wherein the offset Δx can vary depending on the x-coordinate of the laser pulse pair 18, so that the phase position φ(x) can also fundamentally fluctuate along the course direction 2.FIGS. 4 and 6 illustrate how the extent of sidewall scaling, which can be read, for example, from the ratio t y / r, has an effect on the homogeneity of the width B(x) of the microstructure 1 and thus also on the mechanical properties. The three curves of the graph of FIG. 5 illustrate how the width B(x) changes along the course direction 2 with the x coordinate (and in this case each assumes a maximum width B 15), specifically for the three cases of a phase position of 0° / 90° / 180°, which were illustrated in FIGS. 1-3. As the horizontal dashed line in FIG. 5 shows, three microstructures 1 were compared in this case, each having the same average width B. The extent of sidewall scaling (measured in t y / r) was also chosen to be the same. It can be seen in the graph of FIG. 5 that the fluctuation of the width B(x) is the greatest in the case of a spatial phase of φ=0°.In the case of a spatial phase position of φ=180°, by contrast, the microstructure 1 exhibits the smallest variation in the width B(x). In the case of a phase position of φ=180°, therefore, not only are advantages with regard to a higher breaking strength obtained, but, with the same average width B, the spring stiffness of the microstructure 1 can also be significantly reduced, since this depends cubically (for deflections of the microstructure in the substrate plane) on the width B. At a phase position of φ=0°, the local spring stiffness will thus fluctuate considerably, since the fluctuations of the spring width B enter into effect with a third power, as a result of which peaks of the mechanical stress can arise, which can cause a breakage of the spring.A micromechanical microstructure 1 made of glass, as illustrated in FIG. 3, which has a phase position φ(x) of 180° and a comparatively weakly pronounced sidewall scaling, is therefore outstandingly suitable for being used as part of a micromechanical actuator or sensor, since this microstructure 1 is, on the one hand, soft / sensitive, but, on the other hand, exhibits homogeneous mechanical properties, in particular good fracture toughness. On the basis of these properties, a highly qualitative electrostatic actuation / sensor system can be realized in particular with such a microstructure 1.However, even for example a phase position of φ=0°, as shown in FIG. 1, can lead to interesting mechanical properties, in particular when sidewall scaling is just strongly pronounced, which can be utilized in a gain-producing manner. For example, a high non-uniformity of the mechanical properties of the microstructure 1, caused for example by a high variation of the width B (as illustrated for the case φ=0° in FIG. 5 ), can lead to a strong non-linear response behavior of the microstructure 1 in the case of electrostatic actuation, which can be used for example in a stepper motor.As can be clearly seen in FIGS. 1-3, however, the respective spatial phase position φ(x) of the respective laser pulse pairs 18 is homogeneously set there along the course direction 2 of the microstructure 1 within the entire deflection range 12, wherein the phase position in FIG. 1 is φ=0°, in FIG. 2 is φ=90° and in FIG. 3 is φ=180°. Due to the rectilinear profile of the microstructure 1, the phase position φ(x) only fluctuates within the scope of the accuracy with which the laser spots 4 can be placed on the glass substrate 3.As FIG. 6 illustrates, in the case of a straight-line course of the microstructure 1, the effective pulse interval p'=p corresponds precisely to the geometric pulse interval p between two laser points 4 which are directly adjacent on a tool path 5.FIG. 7 shows a further example of a microstructure 1 configured according to the invention, wherein however said microstructure shows a curved profile 2, which can be easily seen on the basis of the center line 19. In such an embodiment, respective laser point pairs 18 can also be considered. However, the effective pulse interval p' ≠p may deviate from the geometric pulse interval p, as illustrated in FIG. 7. Nevertheless, even with such a course of the microstructure 1, the respective spatial phase position φ can be set homogeneously. In the example of FIG. 7, the phase position fluctuates, at least in sections, slightly (by approximately + / -30°) about an average phase position of approximately φ=180°.FIG. 9 shows a further example of a microstructure 1 according to the invention. Here too, respective laser pulses 4 are arranged at a constant pulse spacing p on two mutually opposite tool paths 5 aand 5 b, which however enclose an angle. Accordingly, the outer contour 6 of the microstructure 1 in the xy-plane shows a wedge-shaped course. In this example, too, a spatial phase position φ can be determined for respective laser pulse pairs 18 with respect to the center line 19 shown. In this example, too, the phase position φ is set homogeneously at least in sections and therefore fluctuates only slightly about an average value.FIGS. 13 and 14 each show a scanning electron microscope (SEM) image in oblique view from above onto respective microstructures 1 which are formed according to the invention with a homogeneously adjusted phase position φ. However, it is precisely on the basis of the detailed view of FIG. 13 also in FIG. 14 that the indentations 8 and the ribs 9 lying therebetween, which each extend in the z direction, i.e. transversely to the substrate plane 28, can be seen well. FIG. 14 shows a micromechanical spring element in the form of a thin bending structure 23, while the microstructures 1 of FIG. 13 are designed as respective fingers 24 of an electrostatic comb actuator 25. The left fingers 24 are movable in their respective longitudinal direction (=running direction 2), since these fingers 24 are suspended in a movable manner overall by means of micromechanical spring elements 23 on a main body of the glass substrate 3 (not shown in FIG. 13 ).Some exemplary design and process parameters of microstructures 1 configured according to the invention are listed below in tabular form for different substrate thicknesses and substrate materials, namely:A) Examples of Inventive Microstructures with Low Sidewall ScalingTab. 1: Substrate material: Mempax / BF33 Tab. 1: Substrate material: Mempax / BF33Substrate thickness [μm]500400300200100Etching Diameter (D=2r) [μm]2520201515Pulse Interval (p) [μm]33333Spring width (B) [μm]1010101010Scaling depth (t y) [ μm]0,090, 110, 110,150,15Taper (φ) [°]1,51,51,51,51,5p / r0,240,30,30,40,40ty / r0,00720,01130,01130,02020,02ty / B0,00900,01130,01130,01520,02p / B0,30,30,30,30,3Tab. 2: Substrate material: AF32 (= Low thermal expansion coefficient glass substrate similar to that of a silicon wafer)Tab. 2: Substrate material: AF32 (= Low thermal expansion coefficient glass substrate similar to that of a silicon wafer)Substrate thickness [μm]500400300200100Etching Diameter (D=2r) [μm]6555403020Pulse Interval (p) [μm]55555Spring width (B) [μm]1010101010Scaling depth (t y) [ μm]0, 10, 110, 160,210,32Taper (φ) [°]66666p / r0,153850,18180,250,3330,50ty / r0,002960,00410,00780,01400,03ty / B0,009630,01140,01560,02100,03p / B0,50,50,50,50,5Tab. 3: Substrate material: fused silicaTab. 3: Substrate material: fused silicaSubstrate thickness [μm]500Etching Diameter (D=2r) [μm]20Pulse Interval (p) [μm]5Spring width (B) [μm]10Scaling depth (t y) [ μm]0,32Taper (φ) [°]0,5p / r0,5ty / r0,03ty / B0,03p / B0,5B) Examples of inventive microstructures with pronounced sidewall scalingTab. 4: Substrate material: Mempax / BF33 Tab. 4: Substrate material: Mempax / BF33Substrate thickness [μm]500400300200100Etching Diameter (D=2r) [μm]2520201515Pulse Interval (p) [μm]1010101010Spring width (B) [μm]1010101010Scaling depth (t y) [ μm]1,041,341,341,911,91Taper (φ) [°]1,51,51,51,51,5p / r0,801,001,001,331,33ty / r0,080,130,130,250,25ty / B0,100,130,130,190,19p / B11111Tab. 5: Substrate material: AF32 (= Low thermal expansion coefficient glass substrate similar to that of a silicon wafer)Tab. 5: Substrate material: AF32 (= Low thermal expansion coefficient glass substrate similar to that of a silicon wafer)Substrate thickness [μm]500400300200100Etching Diameter (D=2r) [μm]6555403020Pulse Interval (p) [μm]1515151515Spring width (B) [μm]1010101010Scaling depth (t y) [ μm]0,881,041,462,013,39Taper (φ) [°]66666p / r0, 460,550,751,001,50ty / r0, 030,040,070,130,34ty / B0,090,100,150,200,34p / B1,51,51,51,51,5Tab. 6: Substrate material: fused silicaTab. 6: Substrate material: fused silicaSubstrate thickness [μm]500Etching Diameter (D=2r) [μm]20Pulse Interval (p) [μm]5Spring width (B) [μm]10Scaling depth (t y) [ μm]0,32Taper (φ) [°]0,5p / r0,5ty / r0,03ty / B0,03p / B0,5As can be seen from the numerical values, in these examples the etching diameters D=2r are in the range of less μm, typically the following can apply: r≤50 μm or even r≤20 μm or even r≤10 μm. In this case, the ratio of etching diameter D=2rand substrate thickness t typically applies at least: D / t≤1:5=0.2; with a very large substrate thickness (t≥400 μm), D / t≤1:20=0.05 may even apply. The taper angle φ22 indicated here describes the inclination of the side wall surfaces 13 of the microstructure 1 with respect to the z-axis (=surface normal of the substrate)-compare in this respect FIGS. 10-12.In the example of Table 6, an aspect ratio (=substrate thickness:spring width) of microstructure 1 of 100 is achieved. Sidewall scaling is still very weakly pronounced with a ratio t y / r=0.03. This shows that very homogeneous spring structures with enormous aspect ratio can be produced by means of LIDE, which spring structures are particularly suitable for micromechanics.In the examples of Table 4, the extent of sidewall scaling increases as the substrate thickness decreases. With a substrate thickness of 100 μm, approximately t y / B=194% and t y / r>20% apply. With the same substrate thickness of 100 μm, the ratio of lateral depth t y of the indentation 8 and maximum width B 15 of the microstructure 1 is even 34% in Table 5. Correspondingly, in these examples, distinct indentations 8 or ribs 9 are formed in the side walls 13 of the microstructure 1.In summary, to expand the application possibilities of the previously known LIDE (laser induced deep etching) method, it is proposed, during the production of a micromechanical microstructure 1, to exactly control the position of the laser pulses 4 that define the outer contour 6 of the microstructure 1 by setting a plurality of laser pulses 4 on a glass substrate 3 with a subsequent wet chemical etching step for exposing the microstructure 1. As a result, it is possible on the one hand to control a spatial phase position φ of mutually opposite laser pulses 4 or laser points 4, which are arranged on both sides of the microstructure 1 and form a respective laser pulse pair 18, but also to control a degree of so-called sidewall scaling. By controlling the phase position φ and / or the sidewall scaling, it is possible to influence or set the mechanical properties of the microstructure 1 in a favorable / desired form (cf. FIG. 8 ) shows what can be used advantageously for actuator system or sensor system.List of reference characters1 Microstructure (can be configured in particular as a micromechanical bending structure or as a movable finger) 2 direction of extension (of 1) 3 glass substrate 4 laser pulse (the point of impingement on 3 defines a laser point with xy coordinates on the surface of 3) 5 tool path (along which the laser head is guided and on which the laser pulses are placed) 6 contour (of 1, in particular outer delimitation of 1 in the substrate surface / on the upper side of 1) 7 etching profile (in the xy plane caused by 4) 8 (concave) indentation (in side wall of 1) 9 (convex) rib (in side wall of 1) 10 tool path spacing (or local y spacing between 4) 11 modified regions (in 3) 12 deflection region (of 1) 13 side wall, or side wall surface (of 1) 14 lateral depth (of 8) 15 (maximum) width (of 1 transversely to 2) 16 cantilevers 17 flexure 18 laser pulse pair 19 central axis or central line (of 1) 20 (wet chemical) etched-free region 21 central plane (of 3) 22 taper angle φ 23 bending structure (for example configured as a micromechanical spring element) 24 movable fingers (of 25) 25 micromechanical comb structure 26 surface normal (of 3=z-axis) 27 etching radius 28 substrate plane 29 gap dimension

Claims

Micromechanical microstructure (1) made of glass, in particular configured as - a movable finger (24) of a micromechanical comb structure (25) or - as a micromechanical bending structure (23), in particular as a cantilever, - wherein the microstructure (1) has been exposed from a glass substrate (3) by laser-induced modification of the glass substrate (3) and subsequent wet-chemical anisotropic etching, characterized in that - for producing the microstructure (1), in a deflection region (12) of the microstructure (1), laser pulses (4) have been placed on two mutually opposite tool paths (5a, 5b), which have a respective maximum spacing r perpendicular to a contour (6) along a direction of extent (2) of the microstructure (1), which corresponds to an etching radius (27) r of the wet-chemical etching step, wherein the etching radius (27) rlies in a substrate plane (28) of the glass substrate (3) and - wherein the contour (6) after the wet chemical exposure shows lateral concave indentations (8), each of which shows a curvature with the etching radius (27) r and which are bounded by respective convex ribs (9), and - wherein the laser pulses (4) have been placed such that the characteristic of a sidewall scaling of the microstructure (1) is adjusted in a targeted manner, in order to - improve a homogeneity of the mechanical properties of the microstructure (1) or to - specifically generate an non-homogeneity of the mechanical properties of the microstructure (1), - wherein the sidewall scaling is defined as a ratio t y / r of the local etching radius (27) r and a respective lateral depth t y(14) of the respective indentation (8).Micromechanical microstructure (1) according to Claim 1, wherein the laser pulses (4) have been placed such that a respective spatial phase position φ(x) of respective laser pulse pairs (18), which are formed by in each case two laser pulses (4) lying on the mutually opposite tool tracks (5a, 5b), is set homogeneously along the direction of extent (2) of the microstructure (1) within the deflection region (12) at least in sections, but preferably along the entire deflection region (12), - wherein the spatial phase position φ (x) of a laser pulse pair (18) is defined as φ (x) = 360° Δx / p where Δx is the offset of the two laser pulses (4) of the laser pulse pair (18) in the direction of extent (2) and p is the pulse spacing of two adjacent laser pulses (4) on one of the tool tracks (5a or 5b), preferably so that the phase position φ(x) fluctuates along the course direction (2) by less than + / - 60°, particularly preferably by less than + / - 30°.Micromechanical microstructure (1) according to one of the preceding claims, wherein the respective spatial phase position φ(x) of the respective laser pulse pairs (18) along the extension direction (2) of the microstructure (1) within the deflection region (12) is φ(x) = 180° + / - 60°, preferably φ(x) = 180° + / - 30°, - preferably wherein the following applies to a maximum width B (15) of the microstructure (1) within the entire deflection region (12): B <100 μm, in particular B < 50 μm, preferably B < 20 μm.Micromechanical microstructure (1) according to one of the preceding claims, - wherein, in order to achieve a weakly pronounced sidewall scaling, the laser pulses (4) have been set and the microstructure (1) has been etched free in such a way that the following applies for a ratio of an average pulse spacing p between adjacent laser pulses (4) on one of the two tool paths (5) and the etching radius (27) r, preferably in the entire deflection region (12): p < r, preferably p < r / 2.Micromechanical microstructure (1) according to one of the preceding claims, wherein the ratio of the local etching radius (27) r and the lateral depth t y(14) of the respective indentations (8) is as follows: - t y / r < 0.1, preferably the following applies: t y / r < 0.05, - preferably wherein additionally or alternatively the ratio of the maximum width B (15) of the microstructure transversely with respect to the direction of extension (2) and the lateral depth t y(14) is as follows: t y / B ≤ 0.1, in particular t y / B ≤ 0.05.Micromechanical microstructure (1) according to one of the preceding claims, wherein a respective step angle α formed by a respective laser pulse pair (18) in the deflection region (12) with respect to the direction of extension (2) is at least 2.5°, - in particular wherein the following applies to the step angle α: α = arctan(Δx / Dy) where Δx is the offset of the laser pulses (4) forming the laser pulse pair (18) with respect to one another in the direction of extension (2) and D y is the distance of the two mutually opposite laser pulses (4) transversely with respect to the direction of extension (2).Micromechanical microstructure (1) according to one of the preceding claims, wherein a ratio of an, in particular minimum or maximum, pulse spacing p between two adjacent laser pulses (4) on one of the two tool paths (5) and a maximum width B (15) of the microstructure (1) transversely with respect to the direction of extension (2) applies: p / B ≤ 0.5, preferably p / B ≤ 0.3, - in particular wherein the maximum width B (15) of the microstructure (1) is less than 50 μm, in particular less than 20 μm.Micromechanical microstructure (1) according to Claim 1 or 2, wherein the relationship between the etching radius (27) r and a lateral depth t y(14) of the respective indentations (8) is: t y / r > 0.1, preferably: t y / r > 0.2.Micromechanical microstructure (1) according to Claim 2 or Claim 8, - wherein the respective spatial phase position φ(x) of respective laser pulse pairs (18) along a direction of extent (2) of the microstructure (1) within the deflection region (12) is φ(x) = 0° + / - 60°, preferably φ(x) = 0° + / - 30°, - wherein the following applies preferably to a maximum width B (15) of the microstructure (1) within the entire deflection region (12): B <100 μm, in particular B < 50 μm, preferably B < 20 μm.Micromechanical microstructure (1) according to one of the preceding Claims 2, 8 or 9, - wherein, in order to achieve a strongly pronounced sidewall scaling, the laser pulses (4) have been set and the microstructure (1) has been etched free in such a way that the following applies to a ratio of an average pulse spacing p between adjacent laser pulses (4) on one of the two tool paths (5a or 5b) and the etching radius (27) r, preferably in the entire deflection region (12): p > r, preferably: p > 1.20 r.Micromechanical microstructure (1) according to one of Claims 2 or 8 to 10, wherein a respective step angle α formed by a respective laser pulse pair (18) in the deflection region (12) with respect to the direction of extension (2) is at most 4.0°, preferably at most 2.0°.Micromechanical microstructure (1) according to one of Claims 2 or 8 to 11, wherein a ratio of an, in particular minimum or maximum, pulse spacing p between two adjacent laser pulses (4) on one of the two tool paths (5) and a maximum width B (15) of the microstructure (1) transversely with respect to the direction of extension (2) applies: p / B >0.5, preferably p / B >1.0, - in particular wherein the maximum width B (15) of the microstructure (1) is less than 100 μm, in particular less than 50 μm.Micromechanical microstructure (1) according to one of the preceding claims, wherein the mutually opposite tool paths (5a or 5b) - run approximately or strictly parallel to one another or - enclose an angle or - follow a respective curve.Micromechanical microstructure (1) according to one of the preceding claims, wherein during the production of the microstructure (1) in the deflection region (12) - a minimum pulse spacing of 3 μm and / or - a maximum pulse spacing p of 15 μm on the respective tool track (5a or 5b) has been observed.Microelectromechanical system, in particular configured as a micro-actuator system and / or as a microsensor system, which comprises - at least one micromechanical microstructure (1) according to one of Claims 1 to 7 and / or - at least one micromechanical microstructure (1) according to one of Claims 8 to 14.Use of a micromechanical microstructure (1) made of glass produced by means of laser induced deep etching (LIDE), in particular configured according to one of Claims 1 to 7, - as part of a micromechanical actuator and / or as part of a micromechanical sensor and / or as part of a micromechanical carrier structure, - the characteristic of a sidewall scaling of the microstructure (1) being set in a targeted manner in order to improve the homogeneity of the mechanical properties of the microstructure (1).Use of a micromechanical microstructure (1) made of glass produced by means of laser induced deep etching (LIDE), in particular configured according to one of Claims 8 to 14, - as part of a micromechanical actuator and / or as part of a micromechanical sensor, - the characteristic of a sidewall scaling of the microstructure (1) being set in a targeted manner in order to generate an inhomogeneity of the mechanical properties of the microstructure (1), and - the inhomogeneity being exploited by sensor or actuator.Method for producing a micromechanical microstructure (1) made of glass by means of laser induced deep etching (LIDE), - wherein laser pulses (4) for this purpose are placed in a deflection region (12) of the microstructure (1) on two mutually opposite tool paths (5a, 5b), which have a respective distance r perpendicular to a contour (6) along a direction of extent (2) of the microstructure (1), which corresponds to an etching radius (27) r of a later wet chemical etching step, - wherein the etching radius (27) r lies in a substrate plane (28) of the glass substrate (3) and - wherein the contour (6) after the wet chemical exposure shows lateral concave indentations (8) which each show a curvature with the etching radius (27) r and which are bounded by respective convex ribs (9), characterized in that, - the laser pulses (4) being set on the respective tool path (5) in such a way that a homogeneous extent of sidewall scaling along the direction of extension (2) of the microstructure (1) results and the characteristic of sidewall scaling is specifically set in the process in order - to improve a homogeneity of the mechanical properties of the microstructure (1) or - to specifically generate an non-homogeneity of the mechanical properties of the microstructure (1), - wherein the sidewall scaling is defined as a ratio t y / r of the local etching radius (27) r and a respective lateral depth t y(14) of the respective indentations (8), - in particular wherein the laser pulses (4) are set in such a way that a microstructure (1) according to one of Claims 1 to 14 can be wet-chemically etched free.

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