Method for opening recesses in a substrate

Abstract

The invention relates to a method for producing recesses as depressions in a substrate (2) by locally reducing the material thickness. Here, a modification (5) is produced in the substrate (2) by a spatial beam shaping of a laser beam along a beam axis (4), so that a recess is subsequently produced by the action of a corrosive medium. For this purpose, a plurality of modifications (5) are produced in the substrate (2) along parallel beam axes (4), which modifications have an extension (T) between a first outer surface (6) and a position (P) within the substrate (2) which is spaced apart from a second outer surface (7) opposite the first outer surface (6) by a distance (a). Modifications (5) which are adjacent to one another have a lateral distance (S) with respect to the respective beam axis (4), which is designed to be inversely proportional to the length or depth in the substrate (2), in order to thereby produce a virtually flat surface of the recess.

Description

Technical Field

[0001] The present invention relates to a method for creating at least one discontinuous recess in a substrate, particularly a plate-shaped substrate, as a blind hole without a through portion, or for reducing the material thickness of the substrate to create a material weakness. In this method, the focal point of a laser beam is spatially beam-shaped along the beam axis of the laser beam, and in this method, defect locations are generated in the substrate along the beam axis by means of the laser beam without material removal of the substrate due to the laser beam. One or more defect locations constitute at least one modified portion in the substrate, thereby creating a recess or material weakness in the corresponding region of the modified portion in the substrate by the action of a corrosive medium and by gradual corrosion caused by anisotropic material removal. Background Technology

[0002] The method according to the present invention for precision machining of glass using laser-induced deep etching is well known as LIDE (Laser Induced Deep Etching). The LIDE method can create extremely precise holes and structures at the highest speed and thus opens up the possibility of using glass as a material more extensively in microsystems technology.

[0003] For example, laser-induced depth etching, as known from patent documents WO 2014 / 161534 A2 and WO 2016 / 004144 A1, modifies a transparent material, such as a glass plate, along the beam axis in a strip-shaped area using laser pulses or pulse sequences, typically over the entire thickness of the transparent material, thereby anisotropically etching the modified portion in a subsequent wet chemical etching bath.

[0004] A method for creating recesses, such as blind holes, in a plate-shaped substrate by means of a laser beam is known from patent document WO 2016 / 041544 A1, wherein anisotropic material removal is generated in the modified area of ​​the substrate by the action of a corrosive medium due to gradual etching.

[0005] However, a disadvantage of laser-induced etching processes is that, for example, unilateral etching used to create blind holes or other unilateral recesses requires additional measures to protect the opposite outer surfaces of the substrate, and the modified portion penetrating between the opposite sides also alters the material properties of the substrate on the side away from the recess.

[0006] Patent document EP 2 503 859 A1 describes a selective laser etching process in which a glass substrate is irradiated with a laser focused at a desired location within the glass substrate. By immersing the glass substrate in an etching solution, modified regions are removed from the glass substrate, enabling the creation of complex three-dimensional structures within the glass or blind vias. The etching removal requires, for example, a size of 10 × 10 × 10 μm. 3 Each individual volume is modified, which requires the focal point in the glass substrate to be reoriented accordingly. Although volumes modified in this way can be combined arbitrarily, this requires a significant amount of time and control.

[0007] Patent document DE 10 2018 110 211 A1 describes a method in which the focal position and depth in a substrate can be controlled to produce filamentary damage as very fine blind holes of varying lengths in the substrate. This filamentary damage expands its diameter through subsequent isotropic etching, thereby forming cavities with complex geometries by connecting at least two adjacent filamentary structures.

[0008] Patent document DE 10 2011 111 998 A1 relates to a method for structuring a surface, wherein the surface is irradiated by a laser and regionally modified, for example, in a region below the surface. During etching, recesses are created or enlarged on the surface in the modified region. The laser irradiation causes a change in the material, which in turn alters the effect of the etchant. The material change can be micro-displacement, microcracks, micropores, micro-recesses, or phase transitions, wherein structural changes or melting can be achieved, for example, by laser irradiation.

[0009] Patent document EP 2 600 411 A1 describes using a laser to irradiate a substrate to form multiple modified regions within the substrate, and performing anisotropic etching on the surface to create recesses and protrusions on the substrate surface. Modified regions are formed by repeatedly irradiating the substrate with a laser while simultaneously changing the distance between the substrate surface and the laser convergence point.

[0010] Furthermore, anisotropic etching is known from patent document US 2012 / 0 295 066 A1.

[0011] Furthermore, patent document DE 10 2014 109 792 A1 relates to a process in which point-like surface damage is generated at least segmentally along a dividing line on the surface of a glass element, protruding into the element. This is achieved by forming laser incident points on the surface of the element using a laser beam, thereby creating blind holes or multiple point-like blind holes or linear laser marks. Linear surface damage can be generated by parallel connected elongated holes that are adjacent to each other or particularly advantageously overlap in the region of their openings. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to greatly reduce the cost of creating recesses in a substrate by laser-induced etching.

[0013] According to the present invention, the technical problem is solved by a method for forming at least one recess in a substrate or for reducing the material thickness of the substrate.

[0014] According to the present invention, a method is provided in which a plurality of modified portions are formed into a substrate along beam axes that are spaced apart, particularly parallel to each other, wherein the beam axes have a lateral spacing between each other between a minimum and a maximum value, such that each modified portion extends from a first outer surface of the substrate toward an opposite second outer surface of the substrate up to a position between the outer surfaces at a distance from the opposite outer surface. The basic idea of ​​the invention is based on the idea of ​​creating a modified portion that does not extend across the entire thickness of the substrate, but only extends from the outer surface to a region located between the outer surfaces. This allows for the formation of unilateral recesses by immersion in an etching bath without a covering, such as a resist coating, wherein the substrate is anisotropically etched in the modified region and isotropically etched in the remaining regions. Since the modified portion does not extend to the opposite outer surface, the properties of the substrate at that outer surface remain unchanged, thereby opening up a large number of application possibilities previously only achievable within limited scope. Furthermore, it has been shown that spatial beamforming and the resulting uniform, continuous, and uninterrupted modified portions at predetermined locations from the outer surface into the substrate can achieve significantly more uniform etching removal than a process that sequentially creates multiple volumes with correspondingly varying focal positions along the beam axis. Moreover, by moving the laser beam only parallel to the substrate surface during processing—that is, only across the desired contour without changing the focus—process duration and control costs can be greatly reduced. The energy input of the laser beam is used here to excite or trigger a reaction and to generate defect locations that, generally or individually, produce modified portions, the effects of which are caused or used in subsequent processing steps by the action of a corrosive medium to achieve the desired material removal.

[0015] According to the present invention, a defect location is generated on a substrate by a laser beam, and at least one modified portion is formed on the substrate, which does not result in the removal of the material itself. Then, without prior material removal, anisotropic material removal is performed on the corresponding region of the modified portion in the substrate by the action of a corrosive medium to create a recess or a weak material portion. Therefore, material removal occurs only due to the etching effect of the corrosive medium, rather than directly under the action of the laser beam.

[0016] According to the invention, this produces a particularly advantageous effect: the resulting recess has very low roughness or waviness in the region of the boundary surface at its end, preferably parallel to the outer surface. The protruding structure that can be manufactured in this manner thus possesses a uniform material thickness that has not been achieved to date.

[0017] According to the present invention, if it is necessary to protect individual areas from unwanted etching removal, it is not necessarily necessary to abandon the use of a covering, especially an anti-corrosion coating. The effect of etching on only one side can also be successfully achieved, which is also the technical solution of the present invention.

[0018] Particularly useful is the etching process where the substrate is immersed in an etching bath, especially without any covering or resist coating, thereby producing anisotropic material removal on the first outer surface and isotropic material removal on the second outer surface through etching. This allows, for example, opposing recesses to be formed in the outer surfaces separated only by a thin film, the plane of which can naturally be offset from the central plane between the outer surfaces. This structure cannot be achieved by previous processes, or can only be achieved through costly, multi-stage etching processes.

[0019] A particularly advantageous embodiment of the invention is thus achieved by creating the modified portion through multiple pulses having a consistent beam axis, wherein at least individual pulses with energy inputs below a threshold for modification are introduced, and these pulses only excite the relevant substrate material, and the accumulated energy input creates the modified portion. By introducing a state change along the same beam axis, an expansion of the resulting modified portion or a blunting of the cone angle is produced in the cross-section relative to the beam axis, thus the recess is ideally cylindrical. This achieves a largely flat boundary surface for the recess, unlike prior art where adjacent modified portions result in a tapered recess in the plane of the recess during etching. Since each pulse alters the optical properties of the substrate through the generated excitation and thus produces scattering, the affected area expands concentrically around the beam axis, thereby increasing the volume defined in width transverse to the beam axis. Simultaneously, this forms an end face extending in the cross-section or a slightly tapered recess with obtuse or flat angles. Thus, the modified portion is formed, the length of which remains constant, but its diameter is determined by the number and parameters of the pulses.

[0020] It is advisable to select the distance between adjacent beam axes such that the modified portions overlap. More reasonably, the distance between the beam axes is set such that the modified portions do not overlap, but are adjacent to each other at a small distance, so that the recesses in the modified area created by anisotropic material removal overlap each other transversely with the beam axes.

[0021] To avoid undesirable interactions between the previous modified portions and the laser beam, i.e., a so-called shading effect, when creating adjacent modified portions, the spacing (p) of the modified portions is determined in relation to the diameter (d) of the etched recess according to Formula 10>d / p>1.15. Therefore, the diameter (d) of the corresponding recess is at least 1.15 times the spacing (p) of the modified portions, thereby creating a continuous volume. However, a minimum distance between the modified portions (p) must also be maintained, which must not be less than one-tenth of the diameter, otherwise an edge effect will occur due to shading.

[0022] It has proven particularly suitable here that the modified portion is formed into the substrate in a regular pattern and / or regular structure. This produces a regular pattern on the surface defining the recess, in which undesirable material weaknesses are particularly avoided, and the properties of the surface are largely uniform across the entire extension dimension of the recess.

[0023] For this purpose, it has proven particularly practical that the distance between a modified section and all adjacent modified sections is chosen to be at least substantially uniform, thereby producing, for example, a hexagonal structure for the modified sections. Furthermore, it may be advantageous that the successively arranged modified sections are not opened in the order of adjacent modified sections, but rather, if necessary, the more distant modified sections are opened first. This particularly avoids interactions caused by thermal effects.

[0024] A particularly advantageous embodiment of the invention is achieved in that at least each individual, adjacent, especially parallel, modified portion has different lateral distances in a common transverse plane parallel to the outer surface, and the corresponding lateral distances are set according to the extension dimension, i.e., the length between the position of the modified portion on the outer surface and in the substrate, such that the lateral distance decreases when the extension dimension is larger and increases when the extension dimension is smaller, thereby making the lateral distance inversely proportional to the extension dimension. Surprisingly, when this relationship between the lateral distance and the extension dimension is observed, the resulting recesses or weak points in the material have regular, virtually flat surfaces, whereas this is not the case when the lateral distance is independent of the extension dimension. This advantageous effect according to the invention is based on the understanding that the cross-sectional area of ​​the modified portion decreases in the end section near the position in the substrate due to the converging extension direction of the modified portion. Therefore, the optimal area can be achieved through the relationship between the extension dimensions and lateral distances of adjacent modified portions.

[0025] Another equally preferred variant of the invention is implemented by segmentally creating different modified portions into the substrate along the same or parallel axes. These modified portions extend, on one hand, between a location on a first outer surface and within the substrate, and on the other hand, between a location on a second outer surface and within the substrate, and their extension dimensions can be uniform. This allows for the formation of a three-dimensional contour within the substrate, wherein the laser beam enters the substrate through the same outer surface. The corresponding modified portions extend from the first or second outer surface to predetermined locations within the substrate. Under the corrosive action of a corrosive medium, etching occurs here, particularly by immersion in the etching medium from both sides, resulting in material removal on both or all sides. This allows even complex structures to be produced with relatively low cost by creating modified portions and subsequent etching.

[0026] According to a particularly promising variation of the method according to the invention, the modified portion located between the first or second outer surface of the substrate is formed into the substrate with a uniform extension dimension or at the same distance from the adjacent outer surface along the same axis. For example, the separating surface can be rounded by chamfering on both sides along the circumferential contour of the local area to be manufactured from the substrate. Thus, cutting along a predetermined contour and chamfering are achieved in a single method step to avoid undesirable sharp edges.

[0027] In another equally suitable variation of the method according to the invention, a plurality of adjacent modified portions are formed along parallel axes into the substrate at different locations within the substrate, spaced at different distances from adjacent outer surfaces, wherein the locations lie on a common plane that is not parallel to the outer surfaces. This allows for the creation of planar material weak points or recesses with an orientation inclined relative to the outer surfaces.

[0028] Curved surfaces can also be produced in the same way to avoid discontinuities, especially in the transition regions of recesses and adjacent edge regions of the substrate. This effectively avoids undesirable stress profiles within the substrate, particularly in the presence of external forces, and significantly increases the load-bearing capacity of the resulting structures, such as protruding structures.

[0029] In this way, at least individual recesses and / or material weaknesses, particularly, for example, a substrate with a remaining thickness of less than 100 μm, particularly for example, about 50 μm, can be formed in a substrate, for example, made of glass, with a material thickness between 300 μm and 900 μm, thereby achieving flexible properties at least in the areas of the individual recesses or material weaknesses, and for example, a membrane or hinge can be produced. Attached Figure Description

[0030] This invention allows for different implementations. To further illustrate the basic principles of these implementations, one embodiment is shown in the accompanying drawings and described below. In the drawings:

[0031] Figure 1 A side view of a substrate is shown, the substrate having a modified portion extending into the substrate;

[0032] Figure 2 The modified portion produced in the substrate by etching is shown;

[0033] Figure 3 Multiple modified sections arranged side by side and multiple recesses overlapped by an etching process are shown;

[0034] Figure 4A top view of a substrate is shown, which has a corrugated edge profile created by multiple adjacent recesses.

[0035] Figure 5 The pattern shows a regular shape for the modified portion and the recessed portion;

[0036] Figure 6 A top view of a substrate having multiple modified sections arranged in rows is shown;

[0037] Figure 7 It shows Figure 6 The shown is a cross-sectional side view of a substrate having multiple modified portions with different extension dimensions;

[0038] Figure 8 It shows Figure 6 and Figure 7 The shown is a cross-sectional side view of the substrate after material removal by etching.

[0039] Figure 9 A cross-sectional side view of another substrate with multiple modified portions partially opened along the same axis is shown.

[0040] Figure 10 It shows Figure 9 The shown is a side view of the substrate after material removal by etching. Detailed Implementation

[0041] The following describes in detail, with reference to the accompanying drawings, a method according to the present invention for creating a recess 1, which serves as a recess or protrusion, in the substrate 2 by locally reducing the material thickness 3 of the substrate 2. Figure 1 As can be seen, after the known LIDE (Laser Induced Deep Etching) process, a laser beam (not shown) is generated in the substrate 2 along the beam axis 4 in space, thereby creating defect locations in the substrate 2 along the beam axis 4, which respectively constitute modified parts in the substrate 2.

[0042] Then as Figure 2 As shown, recesses 1 are generated in the corresponding regions of the modified portion 5 in the substrate 2 by the action of a corrosive medium and by the removal of the anisotropic material thus generated.

[0043] Especially by Figure 6 and Figure 7It is understood that, for this purpose, multiple modified portions 5 are formed into the substrate 2 along the parallel beam axis 4. Each modified portion has an extension dimension T between a position P within the substrate 2 on the first outer surface 6 and a position P spaced a distance a from the second outer surface 7 opposite to the first outer surface 6. Thus, each modified portion 5 extends from the outer surfaces 6 and 7 toward the opposite outer surfaces 6 and 7 of the substrate 2 to a position P within the substrate 2. Adjacent modified portions 5 have a lateral distance S with reference to their respective beam axes 4.

[0044] In the modified part 5, the overlapping recess 1 is removed by etching. The recess is formed in the substrate 2 as a groove-shaped depression or protrusion with wavy bottom. The remaining thickness left in the groove-shaped recess 1 constitutes the protrusion structure.

[0045] Figure 4 An enlarged top view of the edge region of the recess 1 is shown. The common shape of the edge region is generated by the lateral distance S between the modified portions 5 and the dimensions of the etched recess 1, which are characterized by the width b, which also determines the radius of the edge region at the corner.

[0046] As a supplement, Figure 5 The top view shows the modified part 5 and the regular pattern of the recess 1 in the edge region of the recess 1.

[0047] The lateral distance S between adjacent modified portions 5 is inversely proportional to the length or depth of the extension dimension T in the substrate 2. Figure 6 It is understood that this involves both the lateral distance S between the modified portion 5 of a column R and the modified portion 5 of an adjacent column R, and the corresponding lateral distance S between different modified portions 5 of the same column R. Thus, according to the present invention, a result is achieved in... Figure 8 The nearly flat surface 8 of the recess 1 shown in the cross-section is achieved by utilizing different cross-sectional shapes according to the extension dimension T of the modified portion 5 and the width b of the modified portion 5 in its respective end region 9, in accordance with the method of the invention.

[0048] Figure 9 and Figure 10 A variation of the method is also shown, wherein different modified portions 5 are formed into the substrate 2 along the same beam axis 4 of the laser beam. These modified portions extend, on one hand, between a first outer surface 6 and a first position P1 within the substrate 2, and on the other hand, between a second outer surface 7 and a second position P2 within the substrate 2. In the illustrated embodiment, the modified portions 5 have the same extension dimension T. By creating an interruption in the modified portions 5 along the beam axis 4, the internal region of the substrate 2 thus enclosed is prevented from material removal during subsequent etching processes. Figure 10The resulting stepped structure after etching removal is shown, which includes, due to the chemical effect, a rounded contour 10, which is shown in a supplementary, localized manner. The resulting rounding or chamfering is optimally suited for manufacturing load-bearing localized areas or blanks of the substrate 2 and can be manufactured in a single common method step according to the invention.

[0049] List of reference numerals

[0050] 1 concave part

[0051] 2 Substrate

[0052] 3. Material thickness

[0053] 4 beam axes

[0054] 5 Modification Department

[0055] 6 outer surface

[0056] 7. Outer surface

[0057] 8 surfaces

[0058] 9 End regions

[0059] 10 outlines

[0060] T-Extension Dimensions

[0061] P position

[0062] a distance

[0063] S Lateral distance

[0064] Column R

[0065] b width

Claims

1. A method for producing at least one recess (1) in a substrate (2) or for reducing the material thickness (3) of the substrate (2), in which method the focal point of a laser beam is spatially beam-shaped along a beam axis (4) of the laser beam, and in which method a defect location is produced in the substrate (2) along the beam axis (4) by means of the laser beam without material removal of the substrate here being produced by the laser beam, wherein One or more defect locations constitute at least one modification (5) in the substrate (2), so that, as a result of the action of a corrosive medium, a recess and / or a material weakening is produced in the substrate (2) in the region of the modification (5) by anisotropic material removal, characterized in that a plurality of modifications (5) are opened into the substrate (2) along parallel, spaced-apart beam axes (4), the modifications having an extension (T) between a first outer surface (6) and a location (P) within the substrate (2) at a distance (a) from a second outer surface (7) opposite the first outer surface (6), so that each modification (5) extends from the outer surface of the substrate in the direction of the opposite outer surface of the substrate to the location (P) within the substrate (2) at a distance (a) from the opposite outer surface, wherein the pitch (p) of the modifications is determined in relation to the diameter (d) of the etched recesses according to the formula 10 > d / p > 1.15, wherein the recesses (1) as protrusions are opened into the substrate (2) by locally reducing the material thickness (3) of the substrate (2) in such a way that the modifications (5) are opened by a plurality of pulses having the same beam axis (4), the overlapping recesses (1) are produced by etching removal in the region of the modifications (5), the protruding structure with waviness at the bottom of the recesses (1) is produced in the substrate (2), wherein the remaining thickness left in the region of the recesses (1) constitutes the protruding structure.

2. The method of claim 1, wherein, The substrate (2) is immersed in an etching bath, so that anisotropic material removal is produced on the first outer surface (6) and isotropic material removal is produced on the second outer surface (7) by the etching action.

3. The method according to claim 1 or 2, characterized in that, The defect locations within the substrate (2) are produced by a series of pulses or by a single pulse.

4. The method according to claim 1 or 2, characterized in that, The lateral distance (S) of the beam axes (4) is adjusted in such a way that the opened modifications (5) do not overlap one another.

5. The method according to claim 1 or 2, characterized in that, The lateral distance (S) of adjacent beam axes (4) is adjusted in such a way that the recesses (1) produced in the region of the modifications (5) by anisotropic material removal overlap one another.

6. The method according to claim 1 or 2, characterized in that, The modifications (5) are opened into the substrate (2) in a regular pattern and / or in a regular structure.

7. The method according to claim 1 or 2, characterized in that, The lateral distance (S) of one modification (5) from all adjacent modifications (5) is selected to be uniform.

8. The method of claim 1 or 2, wherein, The lateral distance (S) of adjacent modifications (5) is reduced when the extension (T) of the modifications (5) is greater.

9. The method of claim 1 or 2, wherein, The modifications (5) are opened into the substrate (2) sectionally along identical and / or adjacent parallel beam axes (4), the modifications extending between the first outer surface (6) and a first location (P1) within the substrate (2) on the one hand and between the second outer surface (7) and a second location (P2) within the substrate (2) on the other hand.

10. The method of claim 1 or 2, wherein, A plurality of modifications (5) are opened into the substrate (2) along the same beam axis (4) between the first outer surface (6) and a first location (PI) within the substrate (2), on the other hand between the second outer surface (7) and a second location (P2) within the substrate (2) with the same extension (T) and / or at the same distance (a) from the adjacent outer surface.

11. The method of claim 1 or 2, wherein, A plurality of adjacent modifications (5) opened into the substrate (2) along parallel beam axes (4) extend into different locations (P) within the substrate (2) at different distances (a) from the same outer surface, wherein the locations (P) lie in a common plane which is non-parallel to the outer surface.

12. The method of claim 1 or 2, wherein, The substrate (2) has a material thickness of between 300 and 900 pm and is provided with at least one recess (1) and / or material weakening having a substrate (2) with a residual thickness of less than 100 pm.

13. The method of claim 1, wherein, The substrate (2) is plate-shaped.

14. The method of claim 12, wherein, The substrate (2) has a material thickness of between 300 and 600 pm and the at least one recess (1) and / or material weakening has a substrate (2) with a residual thickness of between 30 and 80 pm. The substrate (2) is plate-shaped.

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