Glass microstructures, micromechanisms and associated uses

Abstract

To expand the applicability of the known LIDE (Laser-Induced Deep Etching) method, it is proposed to precisely control the position of the laser pulses 4 defining the outer contour 6 of a microstructure 1 by placing multiple laser pulses 4 on a glass substrate 3 and subsequently using a wet-chemical etching step to expose the microstructure 1. This makes it possible, on the one hand, to control the spatial phase position φ of the opposing laser pulses 4 or laser spots 4 arranged on either side of the microstructure 1 and forming each laser pulse pair 18, and, on the other hand, to control the degree of so-called sidewall scalloping. By controlling the phase position φ and / or the sidewall scalloping, it is now possible to influence or target the mechanical properties of the microstructure 1 in a favorable or desired manner (see FIG. 8).

Description

[Technical Field]

[0001] The invention relates in particular to microstructures made of glass, which may be designed as micromechanical bending structures (which may for example form micromechanical spring elements) or as movable fingers of micromechanical comb structures or as cantilevers, which are (totally / totally) etched away from a glass substrate using Laser-Induced Deep Etching (LIDE), i.e. laser-induced depth etching, i.e. are (totally / totally) exposed from the glass substrate by laser-induced modification of the glass substrate followed by wet-chemical anisotropic etching.

[0002] The invention further relates to a (movable) micromechanism having (at least) one such microstructure, as well as to specific uses of such a micromechanism that can be manufactured using the LIDE method, and finally to the associated manufacturing method.

[0003] The LIDE method is known, for example, from EP 2 964 417. Up to now, the LIDE method has frequently been used to etch structures in glass substrates, for example forming the housing of sensors. The present invention deals with how the application of the LIDE method can be expanded.

[0004] In the LIDE method, individual laser pulses are used to (optically) introduce material changes (modifications) into the bulk glass, typically across the entire thickness of the glass substrate, which allows a subsequent wet chemical etching step to anisotropically etch the optically pre-treated / exposed features into the glass substrate, despite the etching solution's inherently isotropic etching properties within the glass substrate. This technique can be used, for example, to create high-quality continuous vias in glass, which is interesting for hermetic construction and connection technology (AVT, or hermetic packaging).

[0005] In the case of the LIDE method, a pulsed laser can be used, so that in this case the glass is modified along the z-direction (=optical axis / surface normal of the glass substrate) with each laser shot (one laser pulse). Here, typically, no change in the beam profile used is applied. Therefore, in the case of the LIDE method, individual small volumes (voxels) within the glass volume are not processed differently with the laser, as in other laser-based (e.g. ablative) glass processing methods. Therefore, the optical processing of the glass substrate is performed non-ablatively in the LIDE method, i.e., the desired material removal in the glass substrate is only achieved during a subsequent wet-chemical etching step, and not with the laser beam.

[0006] Starting from this known prior art, the problem on which the present invention is based is to expand the possible applications of the LIDE method.

[0007] The present inventors have recognized that the wet chemical etching used in the LIDE method always starts from the substrate surface and proceeds from there in the depth direction (z direction) of the glass substrate. Depending on the selected process parameters (e.g., the material of the glass substrate, the etching solution used, and the temperature), the etching radius r in the xy plane (=substrate plane) can decrease more or less significantly along the z direction (i.e., perpendicular to the substrate plane), thereby achieving an edge extension with a gradient relative to the z axis (e.g., in the xz plane). Only a gradient corresponding to a decreasing etching radius r with increasing depth z is possible. However, the etching radius r at the substrate surface always remains the same because it depends only on the etching solution and the total etching time. Therefore, the spatial resolution cannot be changed, which represents a key boundary condition of the LIDE method.

[0008] The respective etching radii r(z) generated in various xy planes at different z-depths in the glass substrate can result in characteristic depressions on the side surfaces (in the xz or yz plane). These depressions are always concave because the etching solution etches isotropically in a specific xy plane, thus forming a convex etching front. This results in glass ribs on the side surfaces removed by the wet etching, protruding between the depressions and extending along the z direction like the depressions. Depending on the selected process parameters, a bulge gradient can appear not only in the y direction (e.g., for structures extending in the x direction) but also in the x direction (e.g., at the tips of such structures).

[0009] Furthermore, it was observed that the ribs, which would otherwise be sharp geometrically, became rounded together with increasing etching duration, which is likely due to chemical processes in the microscopic region. These ribs / bulges are located at a distance L, which corresponds to the pulse interval p, from the laser spot that caused each bulge to form. x These ribs / bulges resemble the wavy pattern that appears on the outside of a seashell, and therefore these structures may also be referred to as "sidewall scalloping."

[0010] Taking these points into consideration, in order to solve the above-mentioned problems, according to the present invention, the mechanical microstructure has the features of claim 1 and / or claim 2.

[0011] Therefore, in particular, according to the present invention, in order to solve this problem in a mechanical microstructure of the type mentioned at the beginning, it can be envisaged that laser pulses are / are arranged on two opposing tool paths to produce the microstructure in the deflection region of the microstructure (i.e., where the bending structure can move in or out of the substrate plane, or where the micromechanical fingers can move relative to the substrate). These tool paths have a respective maximum distance r perpendicular to the (outer) contour (especially the concave depression in the contour) along the extension direction of the microstructure. This distance r corresponds here to the etching radius r of the wet-chemical etching step / is / is used to expose the microstructure, which in this case lies in the substrate plane of the glass substrate. Therefore, in this type of approach, the microstructure is designed monolithically (i.e. entirely) as part of the glass substrate.

[0012] It is further assumed that the laser pulses are arranged (or are arranged) during the production of the microstructure in such a way that the respective spatial phase positions φ(x) of the respective laser pulse pairs are uniformly set along the extension direction of the microstructure within the above-mentioned deflection region. Although a uniform setting of the phase positions should be realized at least partially here to achieve a significant technical effect, preferably the phase positions may be uniformly set along the entire deflection region.

[0013] Alternatively or additionally to these features, it may be envisaged that, in order to achieve this object, during the production of the microstructure, (preferably all) laser pulses (or laser spots) defining the outer contour of the microstructure are set / set on respective continuous (i.e., for example, linear or curved) tool paths, at least in the above-mentioned offset region of the microstructure. In this case, each tool path has a maximum distance to the contour that corresponds exactly to the etching radius r of the wet chemical etching step that is / is used to expose the microstructure (consisting of a glass substrate). Thus, the laser pulses on the tool paths have a distance r to the corresponding concave depression in the contour. Here, the laser pulses can preferably be / may be arranged, at least partially, with a constant pulse spacing p on each tool path (for example, at least three adjacent laser pulses are sequentially set with a pulse spacing p on each tool path). Depending on the selected degree of sidewall scalloping, each tool path may be arranged to increase the depth of each depression in the sidewall of the microstructure by t. y As a result, rt for the contour y It is understood that the minimum distance may be

[0014] The phase position φ(x) here can be understood to mean in particular the following spatial relationship, which describes the laser spot or the resulting depression (as described above): φ(x)=Δx / p′×360°, where φ(x) denotes the spatial phase position at a specific x-position along the extension direction of the microstructure, Δx is the offset between two laser spots facing each other along the extension direction of the microstructure, and p′ is the effective pulse spacing on the central axis of the microstructure (for linear microstructures, p′ is equal to the geometric pulse spacing p between two laser spots directly adjacent on the tool path). This will be explained in more detail further on the basis of the drawings.

[0015] A uniform phase position may be achieved, for example, if the phase position φ(x) varies by less than ±60°, particularly preferably by less than ±30° along the extension direction of the microstructure, where the mean phase position (or mean phase angle φ or mean phase distortion φ) may be selected differently (for example, φ=0° or φ=180°).

[0016] In other words, according to the present invention, it can be assumed that the laser pulses and the resulting etching radii (which occur during wet-chemical exposure of the microstructure in the glass substrate) are / are evenly spaced along two opposing side surfaces (or side walls) of the microstructure so that each opposing laser spot pair (and the resulting depressions) always exhibit a uniform (i.e., for example, almost constant) offset Δx. The offset Δx may vary slightly here, for example, due to the process or based on the geometry of the microstructure, but should always be selected so that a uniform phase position φ(x) results. For example, the variation in Δx may be so slight that the phase position φ(x) in the offset region of the microstructure changes by less than ±60°, particularly preferably by less than ±30°.

[0017] Alternatively or additionally to the above-mentioned phase position control, the present invention also proposes to set the sidewall scalloping of the microstructure in a desired manner in order to set the mechanical properties (either highly uniform or otherwise with a desired non-uniformity). Therefore, according to the present invention, to solve this problem in a mechanical microstructure of the type mentioned at the beginning, for manufacturing a microstructure in the offset region of the microstructure, laser pulses are / are arranged on two opposing tool paths, which have a respective maximum distance r perpendicular to the (outer) contour (particularly the concave depression in the contour) along the extension direction of the microstructure, and this distance r can be assumed to correspond to the etching radius r of the above-mentioned wet-chemical etching step. Since this etching radius r lies in the substrate plane of the glass substrate as described above, the contour exhibits lateral concave depressions after wet-chemical exposure, which each exhibit a curvature with the etching radius r and are defined by respective convex ribs. It is proposed here that the laser pulses are arranged / positioned in such a way that the prominence of the sidewall scalloping of the microstructure is set in a desired manner, in particular at least partially, but preferably along the entire deflection region, in order to improve the uniformity of the mechanical properties of the microstructure or otherwise create a desired non-uniformity in the mechanical properties of the microstructure.

[0018] Sidewall scalloping, for example, is a function of the local etch radius r and the respective lateral depth t of each recess. y Ratio to t y / r. Intended setting may be understood here to mean, in particular, that the sidewall scalloping is consistently weakly pronounced or otherwise consistently strongly pronounced throughout the entire deflection region.

[0019] Therefore, in other words, the degree of sidewall scalloping, particularly the respective lateral depths t yThe size of the lateral depth t can be set with desired spatial resolution by appropriate placement of the laser pulses on the substrate plane along the extension direction. For example, to achieve consistently weak sidewall scalloping, y at least partially, but preferably along the entire deflection region, the following conditions: t y / r<0.1, preferably t y It may be assumed that / r<0.05, where r is the etching radius, applies. In this case, the mechanical properties of the micro / bending structure will be very uniform. Furthermore, in this case, the lateral depth t y may be envisaged to vary by less than 40%, in particular by less than 20%, or even by less than 10%.

[0020] On the other hand, if a desired inhomogeneity is to be generated, which can be utilized, for example, as an actuator or sensor, the respective lateral depth t y at least partially, but preferably along the entire deflection region, the following conditions: t y / r>0.1, preferably t y / r>0.2 It may be assumed that a lateral depth t in the deviation region is applied, which allows for a strong and pronounced sidewall scalloping (related to the etching radius r) to be achieved. In this case, the mechanical properties of the micro / bending structure become non-uniform. In some cases, in such designs, the lateral depth t in the deviation region y Here, it can vary by 50%, or else the variation will be small, which will result in a uniform, strong and pronounced sidewall scalloping, which again leads to the desired non-uniformity.

[0021] The present invention can be used, in particular, to fabricate glass-based microelectromechanical systems (MEMS), or GMEMS, with exceptional mechanical properties. As a first example, mention may be made of spring beams with widths of less than 50 μm, or even less than 20 μm. Such small widths pose a high risk of spring breakage. By creating a uniform phase position, for example, φ(x) = 180° + / - 30°, or even φ(x) = 180° + / - 15°, and / or by creating only weakly, significantly, and uniformly set sidewall scalloping, the spring beam's breakage strength can be significantly improved. This allows such spring structures to be safely used in GMEMS. Positioning the laser spot on a continuous tool path with the above-mentioned maximum distance r from the bending beam's contour ensures that very thin bending beams can be reproducibly fabricated. This also offers advantages for actuator / sensor systems using such bending beams.

[0022] Unlike typical MEMS, which are based on silicon as the substrate material, GMEMS use glass to form the micromechanical structures, more specifically the micromechanical microstructures mentioned above. Unlike silicon, glass is an insulator, not a semiconductor. However, electrical functionality in GMEMS can be achieved by applying a conductive layer, e.g., a thin metal film, onto the glass.

[0023] Therefore, the present invention proposes that the phase position is not simply left to chance, but is deliberately set in specific regions of the microstructure, in particular in regions associated with the microstructure's deflection (deflection regions), and is uniformly configured, for example, with a weakly or strongly pronounced phase distortion, which can be considered here as a maximum at a phase of φ=180° and a minimum at a phase of φ=0°. One advantage of such a design is that the mechanical properties of the microstructure can be better controlled, as will be explained in more detail further below.

[0024] For example, within the framework of the LIDE method, to complete the microstructure, it may be envisaged that for this purpose a series of laser pulses are / are arranged on the laser line in order to introduce modifications into the glass substrate by means of a laser beam, the areas of the glass substrate that are / are modified in this way by means of the laser beam are then etched away in a subsequent wet chemical etching step (as described above in particular).

[0025] The microstructures here can have microscopic dimensions, for example, with respect to their width (in the plane of the substrate) and / or height (normal to the plane of the substrate). For example, the width / height can be in the sub-mm range and less than 100 μm, less than 50 μm, or less than 20 μm (e.g., for very narrow spring beams). In contrast, the length of the microstructures can be in the sub-mm to over mm range, even reaching the cm range, since LIDE can be used to form particularly large GMEMS structures.

[0026] The microstructures thus produced can therefore have at least one microscopic dimension, such as the length and / or width and / or height (across the substrate surface) of the microstructure. Because the precision in positioning of the laser pulse can be several micrometers, very fine microstructures can be exposed by wet chemistry, where the high anisotropy achievable using the LIDE method is again beneficial. Microstructures designed according to the present invention can exhibit, for example, aspect ratios (height:width) of at least 10:1, at least 20:1, or even at least 50:1.

[0027] The microstructure may be designed, for example, as a cantilevered bending beam (spring beam) with a free-standing end, but may also be anchored on both sides, preferably monolithically, in a glass substrate, for example.

[0028] Depending on the application, the microstructures may be designed for in-plane deflection (in the xy plane corresponding to the substrate surface) and / or for out-of-plane deflection (hence in the z-direction). Besides or alternatively to this type of vibration mode, torsional vibrations of the microstructures may also be excitable. For all such applications, the present invention offers technical advantages with regard to the mechanical properties of the glass microstructures, particularly with regard to fracture strength, stiffness uniformity, and reduced lateral sensitivity.

[0029] Thus, a microstructure within the meaning of the present invention may be designed as a micromechanical bending element, in particular as a micromechanical spring element, i.e. for example as a bending beam clamped on one or both sides, but also for example as a membrane, as a torsion beam or as a movable finger of a comb structure, for example of a micromechanical actuator or sensor, etc. The mobility of the fingers may be achieved, for example, in that the fingers are suspended on micromechanical spring elements, which may be designed in particular according to the present invention.

[0030] It should be mentioned here again that each laser pulse can be assigned an associated laser spot on the surface of the glass substrate, which laser spot corresponds to the center of the incident spot of the laser pulse on the surface of the glass substrate. The mentioned tool path here corresponds to the path along which the laser head emitting the laser pulse is guided, where the laser head is here typically guided at a constant distance in the z-direction relative to the substrate surface.

[0031] By uniformly designing the phase position φ(x) of the microstructure (with respect to the contour of the microstructure), it is possible to achieve, inter alia: (i) minimize the spring stiffness of the microstructure, and / or (ii) target (i.e., especially minimize or maximize) the uniformity of the mechanical properties of the microstructure, and / or (iii) target (i.e., especially minimize or maximize) the cross-sensitivity of the microstructure to disturbance variables, and / or (iv) improve the fracture strength of the microstructure. In other words, by targeting the phase position φ(x), it is possible to control and optimize multiple mechanical properties of the microstructure.

[0032] It will thus be appreciated that the microstructures and associated manufacturing methods described herein can be used or utilized to achieve the four technical effects (i)-(iv) above. Low spring stiffness / high uniformity / low lateral sensitivity / high fracture strength can be achieved here by significant phase distortion and / or slight prominence of sidewall scalloping. Conversely, if the width of the microstructures is very slight, slight phase distortion may result, and / or strong and pronounced sidewall scalloping may result in relatively high spring stiffness / low or poor uniformity / high lateral sensitivity / relatively low fracture strength.

[0033] Alternatively or additionally to the above-mentioned features, the problem can also be solved by using a microstructure according to independent claim 2. Therefore, in order to solve the problem, it can be envisaged in particular that the spatial phase position φ(x) of each laser pulse pair along the extension direction of the microstructure in the deflection region is φ(x)=180°+ / −60°, preferably φ(x)=180°+ / −30°. This means that such a design will result in a large spatial phase distortion φ. In such a design, the following condition must also be satisfied for the maximum width B of the microstructure in the entire deflection region: It is also preferred if B<200 μm, in particular B<100 μm, or even B<50 μm or B<20 μm, is applied, since such a feature makes it possible to achieve or obtain microstructures that exhibit a very good mechanical response and have a high fracture strength despite their microscopic size.

[0034] Since both the pulse interval p and the etching radius r are technically limited by process costs, a phase position of approximately 180° allows for the production of more reproducible, more flexible, and uniform micromechanical springs, which require less force and space for deflection, or an improved packing factor and lower peak mechanical stresses during deflection, resulting in higher fracture strength.

[0035] Such phase position, particularly in the context of weakly pronounced sidewall scalloping, can therefore be linked to improved uniformity in the mechanical properties of the microstructure, which is relevant for applications in, for example, microactuator or microsensor systems. For example, certain desired properties of the microactuator system can be tailored, i.e., the electrostatic response behavior of the microstructure can be favorably influenced. This allows for improved GMEMS actuator and / or sensor systems to be achieved compared to microstructures with less targeted sidewall scalloping and / or phase.

[0036] To realize such an advantage, and further to achieve weak and significant sidewall scalloping, it is preferable that, in the entire deviation region, on one of the two tool paths (i.e., arranged on the same tool path), the ratio of the average pulse spacing p between adjacent laser pulses to the etching radius r satisfies the following condition: p <r It may be envisaged that the laser pulses are / are set such that the microstructure is / is etched away such that: p <r / 2 It should be emphasized here that the degree of microscalloping depends only on the ratio p / r, but not on the selected spatial phase position, which is determined by the offset Δx.

[0037] In the extreme case of semicircular depressions, the length of each depression in the sidewall of the microstructure, L x For the following conditions: L x =2r=p would then be applied, whereby the following conditions: p / r=2:1 or p=D=2r, where D is the etching diameter on the substrate surface will be applied.

[0038] In general, in such designs, it is also preferred if directly adjacent laser pulses (on the respective tool paths) have a minimum pulse spacing of at least 3.0 μm, or even at least 5.0 μm, since this avoids optical shadowing effects and achieves uniform etching results, which ensures that the degree of sidewall scalloping is reproducible and can be set as desired during the production of the microstructure. On the other hand, it is advantageous for minimal sidewall scalloping if the pulse spacing p remains below 10.0 μm, in particular below 7.0 μm, at least in the offset region of the microstructure.

[0039] Thus, as already mentioned, the contour of the microstructure (in the region of the sidewalls) typically has lateral concave depressions after wet chemical exposure, each of which exhibits a curvature with an etching radius r and is defined by a respective convex rib. Preferably, t y / r<0.05, or even t y / r<0.03. In this case, the depth t y can be measured transverse to the extension direction of the microstructure.

[0040] Additionally or alternatively to these just described features, the maximum width B of the microstructure transverse to the extension direction and the lateral depth t of each depression may be y For the ratio of t y / B≦0.1, especially t y / B≦0.05 Such a design also defines very weak and pronounced sidewall scalloping.

[0041] Such depressions defined by (more or less pronounced and / or more or less rounded) ribs can be summarized under the term "sidewall scalloping" as mentioned above, since these ribs structure the lateral surfaces of the etched-away microstructures, albeit on a microscopic scale, like a shell. The two designs mentioned above therefore result in particularly flat / slightly pronounced sidewall scalloping, which results in particularly small variations in the width of the microstructures and thus in a high degree of rigidity uniformity. Here, it can be taken into account that the area moment of inertia upon deflection in the substrate plane depends cubically on the width (whereas, in the case of out-of-plane deflection, the area 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 scalloping, the local area moment of inertia can vary significantly along the longitudinal axis of the microstructure. Adjacent ribs are here spaced apart from one another by a distance L x This distance L x corresponds exactly to the pulse spacing p of the associated laser pulse.

[0042] The ribs can typically extend in the z-direction, i.e. perpendicular to the substrate plane. The same applies to the extension of the recesses themselves. Here, these ribs and recesses can also be inclined with respect to the z-axis (in particular with a taper angle φ) depending on the selected degree of anisotropy of the wet chemical etching process used.

[0043] Each depression in the respective sidewall of the microstructure can essentially be assigned to a corresponding laser pulse located at a distance r from the contour (=outline of the substrate surface / top surface of the microstructure). The corresponding laser pulse or laser spot (=incident spot of the laser pulse on the glass substrate surface) is responsible for forming the depression, since the etching front starts isotropically from the laser spot.

[0044] Designing a microstructure with slight sidewall scalloping and a relatively large phase distortion φ(x) can be advantageous, for example, for enabling particularly high fracture strength and thus particularly large deflections of the microstructure. This is because, in the case of slightly pronounced sidewall scalloping, local peaks in mechanical loads are particularly avoided because the first moment of area is designed to be more uniform. In contrast, in sensor applications, this can increase the sensitivity with which the microstructure can capture mechanical vibrations (for the same reasons).

[0045] Particularly weak sidewall scalloping provides benefits, particularly for uniformity of the mechanical properties of the microstructures, when the width of the microstructures is relatively small, and therefore this can be achieved at a given time. y In t y / B, which is particularly relevant when the maximum width B of the microstructure (transverse to the extension direction) is below 100 μm or even below 50 μm.

[0046] Another way of describing the phase distortion between opposing laser pulses or laser spots is the knowledge of the step angle α that each laser pulse pair forms in the offset region of the microstructure 1 relative to the extension direction. This step angle α can be, for example, greater than 2.5°, in particular greater than 5°, or even greater than 7°, or even greater than 9°, depending on the width of the microstructure. In particular, the following condition is applied here for the step angle α: α = arctan(Δx / Dy), where Δx is the offset of the laser pulses forming the laser pulse pair along the extension direction, and Dy is the distance between two opposing laser pulses across the extension direction (or the associated tool path). where the step angle α increases with decreasing width B and increasing offset Δx / increasing phase distortion φ(x).

[0047] If the offset between the laser spots is, for example, Δx=p / 2=5 μm at a pulse spacing of p=10 μm, so that φ(x)=Δx / p'×360°=180° applies, and an etching diameter D=2r=20 μm is used, then for a spring width of B=10 μm, the distance between the tool paths D y For example, D y ≈30 μm. Correspondingly, then, the step angle α≈arctan(Δx / Dy)=arctan(5 / 30)=9.5° results.

[0048] In a further design, the ratio of the (particularly minimum or maximum) pulse spacing p between two (directly) adjacent laser pulses on one of the two tool paths to the maximum width B of the microstructure across the extension direction satisfies the following condition: p / B≦1.0, preferably p / B≦0.75, or even p / B≦0.5 Even in the case of high aspect ratios (e.g., t / B≧40) and / or very small spring widths (B≦20 μm), the following conditions are assumed to apply for microstructures: It may be assumed that p / B<0.4, preferably p / B≦0.3. The pulse interval p used here is the distance L between two adjacent recesses on the sidewall of the microstructure produced by wet chemical etching. x can be read from.

[0049] In this type of design, the maximum width of the microstructure can be less than 50 μm, in particular less than 20 μm. For example, for a minimum pulse spacing of pmin=5 μm and a maximum / nominal width of 10 μm for a microstructure used as a micromechanical spring, a ratio of p / B=0.5 can be set.

[0050] As a technical effect, it can be considered here that the smaller the pulse interval p chosen and therefore the smaller p / B resulting, the weaker and more pronounced the microscalloping will be, and therefore the more uniform the mechanical properties of the microstructure will be.

[0051] Alternatively or additionally to all the features described above so far, the problem can also be solved by using a microstructure according to independent claim 7. For solving this problem, it can therefore be envisaged in particular that the spatial phase position φ(x) of each laser pulse pair along the extension direction of the microstructure within the deflection region of the microstructure is φ=0°+ / −60°, preferably φ=0°+ / −30°. In such an embodiment, it is further provided that the following condition is satisfied for the maximum width B of the microstructure within the entire deflection region: B<100μm, especially B<50μm, and even more so B<20μm may be assumed to apply.

[0052] Such a phase position φ with very small phase distortions, in conjunction with a strongly pronounced sidewall scalloping, can lead to a relatively large inhomogeneity in the mechanical properties of the microstructure. While seemingly unfavorable, such inhomogeneity can have beneficial effects, as will be explained in more detail. For example, certain desired characteristics of the microactuator can be tailored in this way, i.e., the electrostatic response behavior of the microstructure can be favorably influenced. This can result in improved or qualitatively different actuator systems compared to known microstructures, particularly those that do not exhibit sidewall scalloping and / or this type of spatial phase distribution.

[0053] Therefore, in order to achieve a strong and pronounced sidewall scalloping, especially when the uniformity of the phase distortion φ is very small, the ratio of the average pulse spacing p between adjacent laser pulses on one of the two tool paths to the etching radius r preferably satisfies the following condition throughout the entire deviation region: p>r, or p>1.2r The laser pulse is also set so that a laser pulse is applied, further etching away the fine features.

[0054] In the extreme case of a semicircular depression (=maximum pronounced sidewall scalloping), the length of the depression in the extension direction L x Regarding the following conditions: L x =2r=D=p, i.e., therefore, the following condition: p=2r (p is therefore the maximum magnitude) will apply. If the pulse spacing p is reduced from this maximum value, the degree of sidewall scalloping will decrease continuously. However, for values of p > 1.0r, or even p > 1.20r, the sidewall scalloping will still be relatively strong and pronounced. Such strong and pronounced sidewall scalloping, in conjunction with the phase position near 0° just mentioned, can be linked to beneficial mechanical properties of the microstructure that can be technologically exploited, especially for novel types of microactuator and microsensor systems.

[0055] Strong and pronounced sidewall scalloping can alternatively be achieved by the following design or process parameters: It may therefore be assumed that the contour of the microstructure exhibits lateral concave depressions (as already explained), each of which exhibits a curvature with an etching radius r and is defined by a respective convex rib. Then, the etching radius r and the lateral depth t of each depression can be further calculated. y For the ratio of t y / r>0.1, especially t y / r>0.2, or t y / r>0.3 (see Tables 4 and 5) is applicable.

[0056] To achieve a small phase distortion, it may also (additionally or alternatively) be assumed that the step angle α is relatively small. For example, the step angle α may be at most 4.0°, in particular at most 3.0°, and preferably at most 2.0°. Such a small step angle, which can be achieved by a suitable arrangement of the laser pulses (used to etch away the microstructures), results in a small phase distortion φ(x) for a given etching radius r, which is itself well-predetermined for a specific substrate thickness and selected material (glass substrate, etching solution).

[0057] According to a further design, the ratio of the minimum or maximum pulse interval p between two adjacent laser pulses on one of the two tool paths to the maximum width B of the microstructure transverse to the extension direction satisfies the following condition: p / B≧0.5, preferably p / B≧0.75, or p / B≧1.0, or even p / B≧1.5 It may further be envisaged that applies, in which case, in particular, the maximum width of the microstructure may be less than 100 μm, in particular less than 50 μm, or even less than 20 μm. The technical effect here is that the larger the pulse interval p chosen, and thus the larger the resulting p / B, the more pronounced the microscalloping and therefore the more inhomogeneous the mechanical properties of the microstructure. This inhomogeneity may be of technical benefit for novel actuator and sensor mechanisms. For example, for a microstructure used as a spring, with a minimum pulse interval p of at least 10 μm and a maximum / nominal width B of 10 μm, a ratio of p / B=1.0 may result.

[0058] As mentioned above, the phase position φ(x) of the laser pulse pair can / may be defined in particular as φ(x)=360°Δx / p, where Δx is the offset of the two laser pulses of the laser pulse pair in the extension direction of the microstructure, and p is the pulse spacing between two adjacent laser pulses on one of the tool paths.

[0059] The present invention can be advantageously applied, for example, to micromechanical microstructures characterized by opposing tool paths that run almost or strictly parallel to one another. However, the design of the microstructures according to the present invention is also possible when the opposing tool paths are angled or, for example, follow respective curves. In the first two cases, the extension direction of the microstructure can follow a straight line, while in the latter case, it can follow a curve. In such cases, the phase position may also vary locally. However, by appropriately setting the laser spot and appropriately selecting the pulse interval and the etching radius r (which is essentially determined by the substrate material, etching time, and etching solution used), even in such cases, a uniform phase position can be set or formed, at least partially, along the extension direction of the microstructure, with either a large or small phase position, depending on the task.

[0060] To ensure a reproducible process / production of the microstructures, it may be assumed that a minimum pulse spacing of 3 μm and / or a maximum pulse spacing of 15 μm, especially 10 μm, is maintained, particularly during the production of the microstructures in the offset region. This can be seen, for example, from the prominence of sidewall scalloping, since, as already mentioned, the spacing of the ribs of the sidewall scalloping corresponds exactly to the pulse spacing of the associated laser pulses and is responsible for the respective sidewall etching that produced the ribs.

[0061] For example, if only slight sidewall scalloping is to be formed, it may be advantageous to select a pulse interval in the range of 2 μm to 8 μm, preferably in the range of 3 μm to 5 μm. Such values are possible, for example, for substrate thicknesses between 100 μm and 500 μm. On the other hand, if more pronounced sidewall scalloping is to be the result, or if more pronounced results are permitted, the pulse interval may be selected to satisfy the following conditions: p ≥ 7 μm, especially p ≥ 10 μm In some cases it may be useful to choose to apply

[0062] The invention can be applied particularly advantageously to micromechanisms, which can have at least one microstructure according to the invention or a plurality of microstructures according to the invention, for example designed as fingers of a comb actuator or a comb sensor.

[0063] The present invention further proposes a specific application or use of the microstructure or such a micromechanism according to the present invention. Therefore, to achieve this object, the use of a micromechanical microstructure made of glass, in particular manufactured using 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 support structure, preferably manufactured using electrostatic activation or capacitive sensor principles. Here, the microstructure may be designed, as explained above, in particular according to any one of claims 1 to 7, i.e., to have a relatively large phase shift and / or a specifically designed, particularly slightly pronounced sidewall scalloping. In such a use, in particular, the specifically designed phase shift φ(x) of the microstructure and / or the specifically designed pronouncement of the sidewall scalloping can be used to improve the uniformity of the mechanical properties of the microstructure, as already explained in detail above. These microstructures can here form the spring elements of the actuator / sensor system or the fingers of, for example, a micromechanical comb structure, which is relevant for example for linear as well as rotary microactuator systems.

[0064] Additionally, micromechanical microstructures manufactured using LIDE can be used as part of micromechanical actuators and / or as part of micromechanical sensors, preferably using electrostatic activation or capacitive sensor principles, even by deliberately setting the phase position φ(x) of the microstructure and / or the prominence of the sidewall scalloping to generate inhomogeneities in the mechanical properties of the microstructure that can be used or utilized as sensors or actuators. Such glass microstructures, preferably with slight phase distortions and / or pronounced sidewall scalloping, can be used, in particular, to realize micromechanical stepping motors. In this case, the step width of the motor can correspond exactly to the (local) period of the sidewall scalloping.

[0065] Finally, to solve the problem mentioned at the beginning, a method for manufacturing a micromechanical microstructure made of glass using LIDE is also proposed. In this method, as already explained in more detail above in connection with the microstructure according to the invention, laser pulses are arranged on two opposing tool paths in the deflection region of the microstructure. As mentioned above, the laser pulses or the associated laser spots (already in the layout) have a respective distance r from the contour of the microstructure (more precisely, from the respective associated concave depression), which corresponds to the etching radius r of a subsequent wet-chemical etching step. This etching step is used to expose the microstructure in the glass substrate, thereby enabling the microstructure to be movable in the plane of the glass substrate or perpendicular thereto. The method can be characterized here by the laser pulses being set in such a way that, on each laser line, (i) a uniform distribution of the spatial phase position φ(x) and / or (ii) a uniform degree of sidewall scalloping (which can be created and defined as described above) occurs along the extension direction of the microstructure, which of course has already been explained in detail above in relation to the microstructure. That is, here, the laser pulses / laser spots can be set in such a way that the microstructure is removed as described above, in particular by wet-chemical etching as claimed in any one of claims 1 to 14.

[0066] A uniform distribution of the phase position is understood here to mean in particular that the phase position φ(x) (in particular independently of the extension of the microstructure) does not vary by more than ±60° around the mean phase value φ0, preferably by less than ±30°, over the entire deviation region. In contrast, a uniform setting of the sidewall scalloping means in particular that the phase position φ(x) (in particular independently of the extension of the microstructure) does not vary by more than ±60° around the mean phase value φ0, preferably by less than ±30°. ycan be understood to mean that, over the entire deflection region, the ratio t0 / r does not vary by more than + / - 30% about the average lateral depth t0, preferably by less than + / - 20% or even by more than + / - 10%. Depending on the desired properties of the microstructure, a larger or smaller ratio t0 / r may result here.

[0067] The present invention will now be described in more detail on the basis of examples, without being limited to these example embodiments. Further configurations of the invention can be gleaned from the following description of preferred example embodiments, taken in conjunction with the general description, the claims, and the drawings. In the following description of various embodiments of the invention, elements that are identical in their function are provided with identical reference numerals, even if they differ in design or form. [Brief explanation of the drawings]

[0068] [Figure 1] FIG. 1 shows a first example of a micromechanical microstructure in glass designed according to the present invention. [Figure 2] 10A-10C show further examples of microstructures according to the invention. [Figure 3] 10A-10C show further examples of microstructures according to the invention. [Figure 4] 1 is a schematic diagram showing details of the outer contour of a partial cross section of a microstructure designed according to the present invention. [Figure 5] 1 is a graph showing the width B(x) of a bending beam designed in accordance with the present invention as a function of x-position for three cases of differently shaped phase positions φ(x). [Figure 6] 4 is a further schematic view of a part of a microstructure according to the invention in cross section; FIG. [Figure 7] 1 shows an example of a microstructure according to the present invention, showing a curved shape in the x-substrate plane. [Figure 8] 1-3, a further schematic diagram depicting a microstructure according to the present invention together with a number of design or process parameters. [Figure 9] 10A and 10B show further examples of microstructures according to the invention, the outer contours of which extend at angles to one another; [Figure 10] 1 is a cross-sectional view of a microstructure according to the present invention having an average taper angle. [Figure 11] 10 is a cross-sectional view of a microstructure according to the present invention having a larger taper angle. [Figure 12] 4 is a further cross-sectional view of a microstructure according to the invention with a very slight taper angle; FIG. [Figure 13] FIG. 1 shows scanning electron microscope (REM) imaging of a micromechanical interdigitated structure with finger-shaped microstructures designed according to the present invention. [Figure 14] FIG. 1 shows scanning electron microscope (REM) imaging of a microstructure designed according to the present invention in the form of a thin spring bar.

[0069] Figure 1 shows diagrammatically a micromechanical microstructure 1 in the form of a spring bar 16 exposed using the LIDE (Laser Induced Deep Etching) method from a glass substrate 3 in the form of a glass wafer using wet chemical etching. The drawing of Figure 1 shows here a specific substrate thickness t in the Z direction. glass 1 is a top view of the XY plane of a glass substrate 3 having a spring beam 16. As can be seen, a spring beam 16 is connected on one side to the "bulk" of the glass substrate 3, where it forms a solid joint 17 or one-sided mechanical suspension. This spring beam 16 can deflect primarily in the xy plane, but can also deflect out of plane in the z direction.

[0070] The LIDE (Laser-Induced Deep Etching) method can be used to cut or expose minute glass pieces from a glass substrate 3. Similar to a jigsaw, a laser can be used here to create a contour 6 that describes the outer boundary of the microstructure 1 to be exposed. For this purpose, the present invention proposes that a laser head, which emits a pulsed laser beam, be operated along associated tool paths 5a, 5b that follow the contour 6 at a specific distance (see FIG. 3). However, since the laser is pulsed, the glass substrate 3 is not continuously irradiated by the laser beam. Instead, individual laser pulses 4 are set as laser spots 4 at specific x-y coordinates on the surface of the glass substrate 3. In this case, these laser spots 4 can have a fixed geometric pulse spacing p (measured in μm in the substrate plane) and / or can all be located on the aforementioned tool paths 5a, 5b. The block arrows in FIG. 3 indicate the order in which the tool path 5 is traversed and the laser spots 4 are set (see also FIG. 6).

[0071] For example, if a long, narrow slit is to be cut in a glass substrate 3, a predetermined number of laser pulses 4 are arranged along a tool path 5 with a pulse interval p, typically modifying the entire thickness of the glass substrate 3 with each laser pulse 5. In the subsequent wet-chemical etching process, an etching solution attacks the substrate 3 from the top surface in the z direction. Since the etching rate is isotropic in the xy plane, a circular etching profile 7 with rotational symmetry about each laser spot 4 is generated on the surface (see the circles in Figures 4 and 6-8). This results in the final etching contour 6 of the microstructure 1 showing a distance r (=etching radius 27) from the center of the original laser spot 4 (see Figures 3 or 6). In other words, the etched contour 6 on the surface of the glass substrate 3 shows the maximum distance r to the tool path 5 (projected onto the substrate plane) along which the laser pulses 4 are located. In other words, each laser pulse 4 on the tool path 5 has a distance r to the respective associated depression 8 that results based on the etching radius 27 starting from the respective laser pulse 4 .

[0072] Based on the etching radius r, concave depressions 8 are formed in each sidewall 13 of the microstructure 1, each exhibiting a curvature with an etching radius r27 and defined by respective convex ribs 9, where the depressions 8 as well as the ribs 9 extend along the z-direction (see FIGS. 1-3, 4, and 6-9). These structures within each sidewall 13, which arise during wet-chemical exposure of the microstructure 1, are referred to as sidewall scalloping, because the depressions 8 and the intervening ribs 9 form a structure similar to the inside of a mussel shell.

[0073] Depending on the selected process parameters and thus the degree of anisotropy of the wet-chemical etching, the etching radius 27r in the xy-plane can decrease more or less significantly along the z-direction (i.e., perpendicular to the substrate plane), thereby achieving (for example, in the xz-plane) an extension of the sidewalls 13 of the microstructure 1 that is tapered or forms a taper angle φ with respect to the z-axis, as shown in Figures 10-12. However, on the substrate surface, the etching radius 27r is always the same starting from each laser spot 4. Furthermore, only a gradient corresponding to a decreasing etching radius 27r with increasing depth z is always possible. This results from the fact that the wet-chemical etching always starts from the substrate surface and proceeds from there deeper into the substrate. Of course, this process can start from one side (FIG. 12) or else from both sides of both substrate surfaces (see FIGS. 10 and 11), thus resulting in corresponding symmetrical gradients, each extending in the direction towards a centrally located (in the z direction) plane 21 (which lies parallel to the xy plane).

[0074] As shown in Fig. 11, which shows a cross section of a microstructure 1 according to the invention (where the extension direction 2 of the microstructure 1 runs in the direction of view relative to the drawing), an individual laser spot 4 may already be sufficient to define a slit having a width 2r between the microstructure 1 and the substrate 3. In this case, the etching solution then starts from the laser spot 4 (for example in the positive and negative y directions in Fig. 11) to form an etching radius 27r on both sides in the surface of the glass substrate 3. In this case, the maximum width B15 of the microstructure 1 measured at the surface of the glass substrate 3 (measured transverse to the extension direction 2, i.e. in the y direction in Fig. 11) may be larger than the width B15 that the microstructure 1 exhibits in the illustrated central plane 21 of the substrate 3, depending on the selected taper angle φ. M can deviate significantly from

[0075] However, as Figure 12 shows, the laser spots 4 can also be set adjacent to each other with a very small pulse spacing p, so that the resulting etching radii r overlap (see also Figure 8). If the anisotropy of the laser-induced wet chemical etching is chosen to be very high, nearly vertical sidewalls 13 can be defined, as shown in Figure 12.

[0076] Figure 8 shows in detail how the microstructure 1 of Figure 3 was fabricated. As can be seen from the circles representing the disk-shaped etching profiles 7, each with an etching diameter D = 2r, a series of laser pulses 4 are positioned on two opposing tool paths 5a and 5b within the offset region 12 of the microstructure 1. Because the etching front 7 propagates isotropically in the xy substrate plane, each laser pulse 4 has a distance r to the final outer contour 6 of the microstructure 1, which corresponds exactly to the etching radius 27r of the wet-chemical etching step used to expose the microstructure 1. As Figure 3 shows, the two laser pulses 4 on opposing tool paths 5a and 5b can be combined into a laser pulse pair 18. As shown in Figures 1 to 3 and 8, the two laser pulses 4 of each laser pulse pair 18 can exhibit an offset Δx with respect to the extension direction 2 of the microstructure 1 (corresponding to the x-axis in these figures), and this offset Δx can be between Δx = 0 and Δx = p / 2, for example, when a constant pulse interval p is used.

[0077] Depending on the magnitude of this offset Δx, a spatial phase position φ(x) or a spatial phase distortion φ(x) occurs between each laser spot 4 of each laser spot pair 18. In the example of FIG. 1, the offset Δx=0, and therefore the laser spots 4 of each laser spot pair 18 are arranged in phase (φ=0°) with respect to the extension direction 2. In contrast, in the example of FIG. 3, the phase difference is at its maximum (φ=180°), since the offset Δx is then Δx=p / 2, where p is the pulse spacing, i.e., the distance between two directly adjacent laser spots arranged on the same tool path (e.g., 5b) (see FIG. 8).

[0078] On the other hand, the ratio p / r of the pulse interval p to the etching radius r determines how strong and pronounced the sidewall scalloping depression 8 is. x Here, the pulse interval L x = p (see FIG. 8). Furthermore, the lateral depth t of each recess 8, measured specifically transversely to the extension direction 2, i.e., in the y-axis direction in FIG. y 14 can be determined.

[0079] 1 to 3, for example, there (independently of the respective selected phase positions) the sidewall scalloping along the outer contour 6 in the offset region 12 of the microstructure 1 is only weakly noticeable at small ratios t y / r. This is also true for the microstructure shown in FIG. 7 because, despite its curved course, the laser pulse 4 is set so that the sidewall scalloping is consistently weak and pronounced along the entire deflection region 12, and therefore the microstructure exhibits uniform mechanical properties.

[0080] In contrast, in FIG. 4 or FIG. 9 (respectively), the sidewall scalloping is substantially more intense, i.e., the lateral depth t y14 is selected to be larger compared to the etching radius r. Such pronounced sidewall scalloping already leads to inhomogeneity in the mechanical properties of the bent structure 1, since the width B along the x-axis then varies more strongly along the extension direction x of the microstructure 1, as can be clearly seen from FIG. 5. For a given degree of sidewall scalloping, this variation, and thus the inhomogeneity, results the smaller the phase position selected (for example, compare the course of the average width B for a phase of 0° and a phase of 180°).

[0081] However, it will be appreciated that in both the cases of FIGS. 1-3 and 4-9, the degree of sidewall scalloping throughout the offset region 12 is uniform, since the lateral depth t y 14 is selected to be very slight by proper placement of the laser spot 4.

[0082] That is, it can be asserted that the laser spot 4 in the approach according to the invention does not follow a preset pattern, but is defined or deliberately positioned based on the outer contour 6 of the desired microstructure 1 (i.e., based on the design or geometric parameters of the microstructure 1) to achieve a desired phase position and / or a desired sidewall scalloping. In this respect, the process guidance differs from, for example, deep reactive ion etching (DEEP-RIE), which has long been used for structuring silicon, in which the prominence of the ribs is only predetermined by the process parameters of the dry etching, but is not deliberate / predetermined based on the structure design.

[0083] 8 further shows that the two tool paths 5a, 5b have a distance Dy10. This distance and the selected offset Δx here determine the step angle α that the two laser spots 4 of each laser spot pair 18 make with respect to the extension direction 2, in this case satisfying the following condition: α=arctan(Δx / D y ) applies, whereas the spatial phase position φ(x) is determined as φ=360°Δx / p, where 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 vary essentially along the extension direction 2.

[0084] 4 and 6 show, for example, the ratio t y This figure shows how the degree of sidewall scalloping, which can be read from / r, affects the uniformity of the width B(x) of the microstructure 1, and thus the mechanical properties. The three curves in the graph of FIG. 5 show how the width B(x) changes along the extension direction 2 having the x coordinate (and how the maximum width B15 is assumed in this case), specifically for the three phase positions of 0° / 90° / 180° shown in FIGS. 1 to 3. As the horizontal dashed lines in FIG. 5 indicate, three microstructures 1 each having the same average width B are compared here. The degree of sidewall scalloping (t y / r) are also chosen to be of the same magnitude. In the graph of Figure 5, it can be seen that the variation of the width B(x) is greatest at the spatial phase of φ = 0°.

[0085] In contrast, at a spatial phase position of φ=180°, the microstructure 1 exhibits minimal variation in width B(x). Therefore, a phase position of φ=180° not only offers the advantage of higher fracture strength, but also significantly reduces the spring stiffness of the microstructure 1, since for the same average width B, this depends cubically on the width B (relative to the microstructure deflection in the substrate plane). Therefore, at a phase position of φ=0°, the local spring stiffness varies significantly due to the cube of the variation in the spring width B, which can lead to mechanical stress peaks that can cause the spring to fracture.

[0086] Therefore, a micromechanical microstructure 1 made of glass exhibiting a 180° phase shift φ(x) and relatively weak but pronounced sidewall scalloping, as shown in FIG. 3, is exceptionally suitable for use as part of a micromechanical actuator or sensor because it is flexible / sensitive on the one hand and exhibits uniform mechanical properties, particularly good fracture strength, on the other hand. Based on these properties, particularly high-quality electrostatic activation / sensor systems can be realized using such a microstructure 1.

[0087] However, even a phase position of φ=0°, e.g., as shown in Fig. 1, can be linked to interesting mechanical properties that can be beneficially exploited technologically, especially if the sidewall scalloping is just strongly pronounced. For example, a high inhomogeneity in the mechanical properties of the microstructure 1, caused by, e.g., a high variation in the width B (as shown for the case φ=0° in Fig. 5), can be linked to a strongly nonlinear response behavior of the microstructure 1 upon electrostatic activation that can be exploited, e.g., in a stepper motor.

[0088] 1 to 3, the spatial phase position φ(x) of each laser pulse pair 18 is set uniformly along the extension direction 2 of the microstructure 1 within the entire deflection region 12, with the phase position in FIG. 1 being φ=0°, in FIG. 2 being φ=90°, and in FIG. 3 being φ=180°. Due to the respective linear course of the microstructure 1, the phase position φ(x) here only varies within the limits of the accuracy with which the laser spot 4 can be positioned on the glass substrate 3.

[0089] As shown in FIG. 6, in the case of a linear course of the microstructure 1, the effective pulse spacing p′=p corresponds exactly to the geometric pulse spacing p between two directly adjacent laser spots 4 on the tool path 5.

[0090] FIG. 7 shows a further example of a microstructure 1 designed according to the present invention, except that in this case the microstructure 1 exhibits a curved profile 2, which can be clearly seen based on the center line 19. Even with such a design, each laser spot pair 18 can be observed. However, the effective pulse spacing p' ≠ p can deviate from the geometric pulse spacing p, as shown in FIG. 7. Nevertheless, even with such a profile of the microstructure 1, each spatial phase position φ can be uniformly set. In the example of FIG. 7, the phase position fluctuates, at least partially, only slightly (by about + / - 30°) around an average phase position of about φ = 180°.

[0091] FIG. 9 shows a further example of a microstructure 1 according to the present invention. Here, too, each laser pulse 4 is arranged on two opposing tool paths 5a and 5b with a constant pulse spacing p, but at an angle. Accordingly, the outer contour 6 of the microstructure 1 follows a wedge-shaped course in the xy plane. In this example, too, the spatial phase position φ can be determined relative to the center line 19 shown for each laser pulse pair 18. At least partially, in this example, too, the phase position φ is uniformly set and therefore only fluctuates slightly around the average value.

[0092] 13 and 14 each show scanning electron microscope (SEM) images in a perspective view from above of a respective microstructure 1 formed with a uniformly set phase position φ according to the invention. Not only based on the detailed view of FIG. 13, but also in FIG. 14, the depressions 8 and the ribs 9 present between them and extending in the z-direction, i.e., transverse to the substrate plane 28, are clearly visible. FIG. 14 shows micromechanical spring elements here in the form of thin bending structures 23, whereas the microstructures 1 of FIG. 13 are formed as respective fingers 24 of an electrostatic comb actuator 25. The left fingers 24 are here movable in their respective longitudinal direction (=extension direction 2) because they are movably suspended as a whole from the body of the glass substrate 3 by means of micromechanical spring elements 29 (not shown in FIG. 13).

[0093] Below, some exemplary design and process parameters of a microstructure 1 designed according to the present invention are listed in tabular form for different substrate thicknesses and substrate materials.

[0094] A) Example of a microstructure according to the present invention with slight sidewall scalloping [Table 1] [Table 2] [Table 3]

[0095] B) Example of a microstructure according to the present invention with significant sidewall scalloping. [Table 4] [Table 5] [Table 6]

[0096] As can be seen from these figures, in these examples the etching diameter D=2r varies in the range of a few μm, typically under the following conditions: r≦50 μm, or even r≦20 μm, or even r≦10 μm may apply. Here, the ratio of the etching diameter D=2r to the substrate thickness t typically satisfies at least the following condition: D / t≦1:5=0.2 applies, and for very large substrate thicknesses (t ≥ 400 μm), the following conditions: D / t≦1:20=0.05 The proposed taper angle φ22 describes the inclination of the sidewall surface 13 of the microstructure 1 with respect to the z-axis (=surface normal of the substrate) (see FIGS. 10 to 12).

[0097] In the example of Table 6, an aspect ratio (=substrate thickness:spring width) of 100 is achieved for microstructure 1. The sidewall scalloping is still very weakly noticeable here, with a ratio of ty / r=0.03. This shows that by using LIDE it is possible to produce very uniform, high aspect ratio spring structures that are particularly suitable for micromechanics.

[0098] In the example of Table 4, the degree of sidewall scalloping increases with decreasing substrate thickness. For a substrate thickness of 100 μm, for example, under the following conditions: t y / B=19%, and t y / r>20% For the same substrate thickness of 100 μm, in Table 5, the lateral depth t y to the maximum width B15 of the microstructure 1 is even 34%. Accordingly, in these examples, clear depressions 8 or ribs 9 are formed in the side walls 13 of the microstructure 1.

[0099] In summary, to expand the applicability of the known LIDE (Laser-Induced Deep Etching) method, it is proposed to precisely control the position of the laser pulses 4, which define the outer contour 6 of the microstructure 1, during the production of a micromechanical microstructure 1 by placing multiple laser pulses 4 on a glass substrate 3 and using a subsequent wet-chemical etching step to expose the microstructure 1. This makes it possible, on the one hand, to control the spatial phase position φ of the opposing laser pulses 4 or laser spots 4 arranged on either side of the microstructure 1 and forming the respective laser pulse pairs 18, and, on the other hand, to control the degree of so-called sidewall scalloping. By controlling the phase position φ and / or the sidewall scalloping, it is possible to influence or target the mechanical properties of the microstructure 1 in a favorable / desired manner (see FIG. 8), which can be advantageously utilized in actuator or sensor systems. [Explanation of symbols]

[0100] 1 Microstructures (which may be designed in particular as micromechanical bending structures or movable fingers) 2. (1) Extension direction 3. Glass substrate 4 laser pulse (the incident spot on 3 defines a laser spot with x-y coordinates on the surface of 3) 5 Toolpaths (along these paths the laser head is guided and on these paths the laser pulses are set) 6. Contour (of 1, especially of the outer boundary of 1 within the substrate surface / on the top surface of 1) 7 Etching profile (in the xy plane caused by 4) 8 (concave) depression (in the side wall of 1) 9 (Convex) rib (in the side wall of 1) 10 toolpath distance (or 4 local y distance) 11. Modified Area (within 3) 12 (1) deviation area 13 (1) Side wall or side wall surface 14 (of 14) lateral depth 15 (1 across 2) (maximum) width 16 Spring beam 17 Solid Joint 18 laser pulse pairs 19 (1) central axis or center line 20 (wet chemical) etched away areas 21 (of 3) central plane 22 Taper angle φ 23 Bending structures (e.g. designed as micromechanical spring elements) 24 (of 25) movable fingers 25 Micromechanical comb structure 26 (3=z axis) surface normal 27 Etching Radius 28 Board plane 29 Gap dimensions

Claims

1. A microstructure (1) made of glass, in particular as the moving fingers (24) of a micromechanical comb structure (25), or - a micromechanical bending structure (1), in particular designed as a cantilever, - said microstructures (1) are exposed from the glass substrate (3) by laser-induced modification of said glass substrate (3) followed by wet-chemical anisotropic etching; In the microstructure (1) made of glass, - for producing the microstructure (1) in the deflection region (12) of the microstructure (1), laser pulses (4) are arranged on two opposing tool paths (5a, 5b), the tool paths (5a, 5b) having a respective maximum distance r perpendicular to the contour (6) of the microstructure (1), the maximum distance r corresponding to an etching radius (27) r of a wet-chemical etching step, the etching radius (27) r lying in the substrate plane (28) of the glass substrate (3); The laser pulses (4) are at least partially aligned in the direction of extension (2) of the microstructure (1) within the deflection region (12) such that the respective spatial phase positions φ(x) of the respective laser pulse pairs (18) are aligned in the deflection region (12) but preferably arranged so as to be uniformly set along the entire said deflection area (12); the spatial phase position φ(x) of a laser pulse pair (18) is φ(x)=360°Δx / p, where Δx is the offset of two laser pulses (4) of the laser pulse pair (18) in the extension direction (2), and p is the pulse spacing of two adjacent laser pulses (4) on one of the tool paths (5a or 5b); is defined as Preferably, the phase position φ(x) varies along the extension direction (2) by less than + / −60°, particularly preferably by less than + / −30°; A microstructure (1) made of glass.

2. A microstructure (1) made of glass, in particular a microstructure (1) made of glass according to the preamble of claim 1 or as defined in claim 1, The microstructure (1) is exposed from the glass substrate (3) by laser-induced modification of the glass substrate (3) followed by wet-chemical anisotropic etching. In the microstructure (1) made of glass, - for producing the microstructure (1) in the deflection region (12) of the microstructure (1), laser pulses (4) are arranged on two opposing tool paths (5a, 5b), the tool paths (5a, 5b) having respective maximum distances r perpendicular to a contour (6) along the extension direction (2) of the microstructure (1), the maximum distances r corresponding to etching radii (27) r of the wet-chemical etching step, the etching radii (27) r lying in the substrate plane (28) of the glass substrate (3), the contour (6) exhibiting lateral concave depressions (8) after wet-chemical exposure, the depressions (8) each exhibiting a curvature with the etching radii (27) r and defined by respective convex ribs (9); the laser pulses (4) are arranged to target the prominence of the sidewall scalloping of the microstructure (1) in order to improve the uniformity of the mechanical properties of the microstructure (1) or to target the non-uniformity of the mechanical properties of the microstructure (1); - the sidewall scalloping is determined by the local etching radius (27) r and the respective lateral depth t of each recess (8). ｙ (14) and the ratio t ｙ / r, A microstructure (1) made of glass.

3. a spatial phase position φ(x) of each of the laser pulse pairs (18) along the extension direction (2) of the microstructure (1) in the deflection region (12) is φ(x)=180°+ / −60°, preferably φ(x)=180°+ / −30°; Preferably, the maximum width B (15) of said microstructure (1) within the entire deflection zone (12) satisfies the following condition: B<100 μm, in particular B<50 μm, preferably B<20 μm 3. The microstructure (1) according to claim 1 or 2, wherein:

4. In order to achieve a weakly pronounced sidewall scalloping, preferably, the ratio of the average pulse spacing p between adjacent laser pulses (4) on one of the two tool paths (5) to the etching radius (27) r over the entire deviation region (12) satisfies the following condition: p<r, preferably p<r / 2 4. The microstructure (1) according to claim 1, wherein the laser pulse (4) is set so that a laser pulse of .gtoreq..times ...

5. said contour (6) presents lateral concave depressions (8) each presenting a curvature with said etching radius (27) r and being defined by respective convex ribs (9); the local etching radius (27) r and the lateral depth t of each recess (8); ｙ (14) with the following conditions: t ｙ / r<0.1, preferably t ｙ / r<0.05 is applied, Preferably, additionally or alternatively, the maximum width B (15) of the microstructure transverse to the extension direction (2) and the lateral depth t ｙ (14) with the following conditions: t ｙ / B≦0.1, especially t ｙ / B≦0.05 5. The micromechanical structure (1) according to claim 1, wherein:

6. each step angle α that each laser pulse pair (18) forms in the deflection region (12) relative to the extension direction (2) is at least 2.5°; In particular, for said step angle α, the following conditions: α=arctan(Δx / D ｙ ), where Δx is the mutual offset of the laser pulses (4) forming the laser pulse pair (18) in the extension direction (2), and Dy is the distance between two opposing laser pulses (4) across the extension direction (2).

6. The micromechanical microstructure (1) according to claim 1, wherein:

7. The ratio of the minimum or maximum pulse spacing p between two adjacent laser pulses (4) on one of the two tool paths (5) to the maximum width B (17) of the microstructure (1) across the extension direction (2) satisfies the following condition: p / B≦0.5, preferably p / B≦0.3 is applied, The micromechanical microstructure (1) according to any one of claims 1 to 6, in particular the maximum width (17) of the microstructure (1) is less than 50 μm, in particular less than 20 μm.

8. the spatial phase position φ(x) of each of the laser pulse pairs (18) along the extension direction (2) of the microstructure (1) within the deflection region (12) is φ(x)=0°+ / −60°, preferably φ(x)=0°+ / −30°; Preferably, the maximum width B (15) of said microstructure (1) within the entire deflection zone (12) satisfies the following condition: B<100 μm, in particular B<50 μm, preferably B<20 μm A micromechanical microstructure (1) according to the preamble of claim 1, in particular according to claim 1 and / or claim 2, to which

9. In order to achieve a strong and pronounced sidewall scalloping, the ratio of the average pulse spacing p between adjacent laser pulses (4) on one of the two tool paths (5) to the etching radius (27) r preferably satisfies the following condition throughout the deviation zone (12): p / r>1:2, therefore p>r, preferably p>1.20r 9. The micromechanical microstructure (1) according to claim 1, wherein the laser pulse (4) is set so that a laser pulse of .gtoreq..times ...

10. said contour (6) presents lateral concave depressions (8) each presenting a curvature with said etching radius (27) r and being defined by respective convex ribs (9); the etching radius (27) r (15) and the lateral depth t of each recess (8); ｙ (14) with the following conditions: t ｙ / r>0.1, preferably t ｙ / r>0.2 10. The micromechanical microstructure (1) according to any one of claims 1 to 9, wherein:

11. 11. The micromechanical microstructure (1) according to any one of claims 8 to 10, wherein each step angle α formed by each laser pulse pair (18) in the deflection region (12) relative to the extension direction (2) is at most 4.0°, preferably at most 2.0°.

12. The ratio of the minimum or maximum pulse spacing p between two adjacent laser pulses (4) on one of the two tool paths (5) to the maximum width B (17) of the microstructure (1) across the extension direction (2) satisfies the following condition: p / B>0.5, preferably p / B>1.0 is applied, - Micromechanical microstructure (1) according to any one of claims 8 to 11, in particular the maximum width (17) of the microstructure (1) is less than 100 μm, in particular less than 50 μm.

13. The opposing tool paths (5a or 5b) - extend almost or strictly parallel to one another, or - at an angle, or - A micromechanical microstructure (1) according to any one of claims 1 to 12, which follows a respective curve.

14. During the production of the microstructure (1) in the deflection region (12), - A minimum pulse spacing of 3 μm, and / or The micromechanical microstructure (1) according to any one of claims 1 to 13, wherein a maximum pulse spacing of -15 μm is maintained on each said tool path (5a or 5b).

15. A micromechanism, in particular a micromechanism designed as a microactuator system and / or a microsensor system, said micromechanism comprising: - at least one microstructure (1) according to any one of claims 1 to 7, and / or - A micromechanism comprising at least one microstructure (1) according to any one of claims 8 to 14.

16. Micromechanical microstructures (1) made of glass, in particular according to any one of claims 1 to 7, produced by means of laser-induced deep etching (LIDE). Use as part of a micromechanical actuator and / or as part of a micromechanical sensor and / or as part of a micromechanical support structure, - Use in which the phase position φ(x) of the microstructure (1) and / or the prominence of the sidewall scalloping are deliberately set to improve the uniformity of the mechanical properties of the microstructure (1).

17. 15. A micromechanical microstructure (1) made of glass according to any one of claims 8 to 14, produced by means of laser-induced deep etching (LIDE). - use as part of a micromechanical actuator and / or as part of a micromechanical sensor, - Use in which the phase position φ(x) of the microstructure (1) and / or the prominence of the sidewall scalloping are deliberately set to generate inhomogeneities in the mechanical properties of the microstructure (1), which are exploited in a sensory or actuator manner.

18. 1. A method for fabricating micromechanical microstructures made of glass using laser-induced deep etching (LIDE), comprising: For this purpose, laser pulses (4) are arranged in the deflection area (12) of the microstructure (1) on two opposing tool paths (5), the tool paths (5) having a respective distance r to the contour (6) of the microstructure (1), the distance r corresponding to an etching radius (27) r of a subsequent wet-chemical etching step, - said laser pulses (4) on each laser line (5), - a uniform distribution of the spatial phase positions φ(x), and / or - uniform degree of sidewall scalloping The microstructure (1) is set to occur along the extending direction (2), In particular, said laser pulse (4) - A method, characterized in that the microstructure (1) according to any one of claims 1 to 14 is configured to be removable by wet chemical etching.

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