WO2023088912A1

WO2023088912A1 - Method for the laser processing of a workpiece

Info

Publication number: WO2023088912A1
Application number: PCT/EP2022/082020
Authority: WO
Inventors: Daniel FLAMM; Myriam Kaiser; Jonas Kleiner
Original assignee: Trumpf Laser- Und Systemtechnik Gmbh
Priority date: 2021-11-18
Filing date: 2022-11-15
Publication date: 2023-05-25
Also published as: DE102021130129A1

Abstract

The invention relates to a method for the laser processing of a workpiece (104) which has a transparent material (102). In the method, multiple focal elements (120, 120') are provided by means of an input laser beam (108), and the focal elements (120, 120') act on the material (102), wherein material modifications (138) are produced in the material (102) along a specified processing line (128) as a result of the focal elements (120) acting on the material (102), which can be detached at said processing line by means of an etching process using at least one wet-chemical solution, and as a result of the focal elements (120') acting on the material (102), at least one separate etching entrance (144) is formed in the material (102) in order to supply the at least one wet-chemical solution to the processing line (128) from an outer face (132, 134) of the workpiece (104).

Description

Process for laser machining a workpiece

The invention relates to a method for laser machining a workpiece that has a transparent material.

DE 10 2014 116 958 A1 discloses a diffractive optical beam-shaping element for impressing a phase curve on a laser beam provided for laser processing of a material that is largely transparent to the laser beam, with a phase mask that is designed to impress a plurality of beam-shaping phase curves on the laser beam striking the phase mask is, wherein at least one of the plurality of beam-shaping phase curves is associated with a virtual optical image that can be imaged in at least one elongated focus zone for forming a modification in the material to be processed.

DE 10 2019 218 995 A1 discloses a method for laser beam modification of a material that is at least largely transparent to the laser beam, in which a focal zone of an individual pulse of the laser beam that is elongated in the direction of beam propagation is brought into interaction with the material and in which the interaction of the individual pulse with the Material a channel penetrating the material from a first end face to a second end face is produced with a channel width dimension of at most 1 pm.

EP 3 597 353 A1 discloses a method for separating a transparent material by means of an elongated focal zone of a laser beam.

JP 2020 004 889 A discloses a method for separating and in particular beveling a transparent material, a plurality of focal points for laser processing of the material being generated by means of a spatial light modulator. Methods for forming a beveled edge region on a transparent material by means of a laser beam are known from US 2020/0147729 A1 and US 2020/0361037 A1.

WO 2016/089799 A1 discloses a method for separating a transparent material using a plurality of parallel, non-diffractive laser beams.

The object of the invention is to provide a method as mentioned in the introduction, which enables the material of the workpiece to be separated with an increased quality of the separating surface.

In the method mentioned at the outset, this object is achieved according to the invention in that a plurality of focus elements are provided by means of an input laser beam and the material is exposed to the focus elements, material modifications being formed in the material along a predetermined processing line by exposure of the material to the focus elements, at which the material can be separated by etching using at least one wet-chemical solution, and wherein at least one separate etching access for supplying the at least one wet-chemical solution from an outside of the workpiece to the processing line is formed by subjecting the material to the focus elements in the material.

The wet-chemical solution can be introduced into the volume of the material in a targeted manner by means of the at least one etching access. It is thereby possible to achieve an improved supply of the wet-chemical solution to material modifications lying on the processing line, which are positioned in an inner region of the material, i.e. which are arranged in the interior of the material at a distance from an outer side of the material.

In order to separate the material of the workpiece along the processing line, it is provided that an etching process is carried out on the material after the material modifications have been formed, using the at least one wet-chemical solution. An improved and/or more uniform supply of the wet-chemical solution to the material modifications arranged along the processing line can be achieved by means of the at least one etching access. In particular, the wet-chemical solution can be supplied more uniformly in terms of time and space to the material modifications assigned to the processing line. For example, different material modifications of the processing line can be supplied with a well-defined quantity of the wet-chemical solution within a specific time window. Temporal fluctuations in the supply of the wet-chemical solution and/or fluctuations in the supplied quantity of the wet-chemical solution are reduced.

Due to the improved and more uniform supply of the wet-chemical solution, the etching process for separating the workpiece can be carried out with a reduced etching time. In addition, the material modifications can be made more homogeneous and/or of the same type. This allows the workpiece to be separated with a more homogeneous and/or smoother separating surface. This results in an increased quality of the parting surface.

An outside of the workpiece is to be understood in particular as an outside of the material of the workpiece. The focus elements are introduced into this material.

In particular, the material modifications formed along the processing line enable the material to be separated by etching using the at least one wet-chemical solution. In particular, the focus elements arranged along the processing line are spaced apart and/or have such an intensity that the material modifications formed by means of the focus elements along the processing line enable the material to be separated by etching using the at least one wet-chemical solution.

By subjecting the material of the workpiece to the focus elements, material modifications are formed which are arranged in the material at positions and/or distances corresponding to the focus elements. In particular, the distance between the mutually adjacent focus elements corresponds to a distance between mutually adjacent material modifications, which are formed in the material of the workpiece by means of these focus elements. In principle, however, it is also possible for a plurality of material modifications to be formed by means of one focus element, for example if this has a Bessel-like shape.

In particular, it can be provided that one or more of the provided focus elements are arranged along the processing line in order to form the material modifications along the processing line.

In particular, the focus elements provided are each arranged at different spatial positions in the material. The spatial position of a specific focus element is to be understood in particular as a mid-point position of the corresponding focus element.

In particular, it can be provided that the material is acted upon simultaneously with the focus elements for forming the material modifications along the processing line and with the focus elements for forming the at least one etching access. As a result, in particular the material modifications assigned to the processing line and the material modifications assigned to the etching access are formed simultaneously.

In principle, it is also possible for the material to be subjected to at least one focus element to form the material modifications along the processing line and at least one focus element to form the at least one etching access at a different time and/or in succession. As a result, in particular the material modifications assigned to the processing line and the material modifications assigned to the etching access are formed with a time offset or in succession in time.

The fact that a plurality of focus elements are provided by means of the at least one input laser beam can in particular be understood to mean that the plurality of focus elements are provided simultaneously. However, this can also be understood to mean that one or more focus elements are each provided with a time offset, ie that, for example, at a at a certain point in time at least one focus element is available for laser processing of the workpiece at a certain position and at another point in time at least one further focus element is available for laser processing of the workpiece at another position. For example, at least one focus element is then initially provided in order to form the material modifications assigned to the processing line, and then at least one further focus element is provided with a time offset in order to form the material modifications assigned to the at least one etching access. The at least one focus element and the at least one further focus element provided at different times can be designed differently with regard to their shape and/or their intensity profile, but are not necessarily so.

In particular, it can be provided that the at least one etching access includes material modifications and/or cracks formed in the material of the workpiece by means of the focus elements or is formed from material modifications and/or cracks formed in the material of the workpiece. In particular, the material modifications and/or cracks associated with the etching access allow the at least one wet-chemical solution to be conducted through the material.

It can be favorable if the at least one etching access is designed for supplying wet-chemical solution from the outside of the workpiece into an inner area of the material lying on the processing line. As a result, by means of the etching access, wet-chemical solution can be guided to material modifications of the machining line that are located in the inner region.

In particular, the at least one etching access is separate from the processing line and/or an additional access for supplying the at least one wet-chemical solution from the outside to the processing line.

The at least one etching access and in particular the at least one etching access associated material modifications and / or cracks have in particular exclusively the purpose of at least one wet-chemical solution from the outside of the workpiece to the processing line and in particular to feed the material modifications and/or cracks associated with the processing line. In particular, the at least one etching access is not part of the processing line.

In particular, the purpose of the at least one etching access is not to separate the material of the workpiece along an extension of the at least one etching access. In particular, a target shape and/or target cross-sectional shape of a separating surface to be formed or formed when the workpiece is separated is not defined and/or influenced by an extension of the at least one etching access.

In particular, the at least one etching access is an access that is spatially separated and/or spatially separated from the processing line at least in sections for supplying wet-chemical solution from the outside of the workpiece into an inner region of the material located on the processing line. In this way, spatially separated accesses for supplying wet-chemical solution to the material modifications of the processing line can be provided.

In particular, material is arranged at least in sections between the processing line and the at least one etching access, which material is in particular unmodified and/or contains no material modifications and/or contains no cracks.

In particular, the machining line and/or the at least one etching access extend from the outside of the workpiece into an inside area of the material.

In particular, material modifications and/or cracks are assigned to the processing line or the at least one etching access, which extend from an inner area of the material to the outside of the workpiece. This allows a wet-chemical solution to be coupled into the processing line or into the etching access on the outside. For example, the at least one wet-chemical solution can be fed to the material modifications of the processing line by firstly penetrating the material modifications of the processing line on the outside of the workpiece and secondly being guided via the at least one etching access to the material modifications of the processing line arranged in the interior of the material.

In particular, the at least one etching access includes a passage and/or a channel for conducting the at least one wet-chemical solution. This allows the wet-chemical solution to be guided through the material of the workpiece on a defined path by means of the etching access.

It can be advantageous if the at least one etching access extends from an outside of the workpiece to the machining line and/or from an outside of the workpiece to the material modifications assigned to the machining line. As a result, the wet-chemical solution can be supplied to these material modifications in a targeted manner by means of the etching access.

In particular, the workpiece is divided into two or more workpiece segments when it is separated, or at least one workpiece segment is severed from the workpiece when it is separated.

A workpiece segment formed by separating the workpiece can be a useful segment and/or good piece segment, which in particular has a separating surface that has a shape that corresponds to a shape of the processing line and/or processing surface. Furthermore, a workpiece segment formed by cutting the workpiece can be a scrap segment and/or scrap segment.

In particular, it can be provided that the at least one etching access is formed in a region of the material which, after the workpiece has been separated, is positioned along the processing line on or in a waste segment formed during the separation of the workpiece. In particular, the waste segment is separated at one or more of the etching accesses formed there. In particular, it can be provided that at least one etching access is formed, which extends with respect to a thickness direction of the workpiece from an outside of the workpiece to a penetration depth of at least 1% and in particular at least 10% and in particular at least 20% of a thickness of the material of the workpiece .

Provision can be made for the at least one etching access to be oriented transversely and in particular perpendicularly to an outside of the workpiece.

It can be provided that the at least one etching access in the material of the workpiece opens into the processing line and in particular opens into material modifications and/or cracks associated with the processing line.

It can be provided that the at least one etching access is a tangential continuation of a section of the machining line and/or opens tangentially into the machining line.

It can be provided that the at least one etching access opens transversely and in particular perpendicularly into the processing line.

In particular, it can be provided that at least two etching accesses are formed, a first etching access extending from a first outside of the workpiece to the processing line and a second etching access extending from a second outside of the workpiece to the processing line.

The first outer side and the second outer side of the workpiece are spaced apart from one another, for example in the thickness direction of the workpiece. The first outside and the second outside can lie in planes parallel to one another or in planes oriented transversely and in particular perpendicularly to one another.

In particular, it can be provided that the workpiece is etched by means of the at least one wet-chemical solution along the machining line and/or is separated along a processing surface assigned to the processing line. In particular, the workpiece is separated after the material has been exposed to the focus elements and/or after the material modifications have been formed.

In particular, the material is separated during etching by means of the at least one wet-chemical solution at one or more of the etching accesses formed. As a result, for example, a waste segment formed during the separation of the material is in turn subdivided into further segments. This is in particular a side effect which occurs when the material is etched using the at least one wet-chemical solution.

In particular, separating the workpiece along the processing surface results in a workpiece segment with a separating surface whose geometry corresponds to the processing surface.

For etching, the material of the workpiece is, for example, partially or completely exposed to the at least one wet-chemical solution. Provision can be made for the etching to take place in an ultrasonically assisted etching bath. In addition, it can be provided that the material for the separation is additionally subjected to a mechanical stress and/or force, and/or that the material for the separation is additionally subjected to heat.

It can be favorable if the input laser beam is divided into a plurality of partial beams by means of a beam splitting element and the focus elements are formed by focusing partial beams coupled out of the beam splitting element. As a result, the focus elements can be formed as copies of one another. In particular, this allows the focus elements to be introduced into the material of the workpiece in a technically simple manner at different positions and/or at different distances.

For the same reason, it can be favorable if a division of the

Input laser beam by means of the beam splitting element by phase imprinting takes place on a beam cross section of the input laser beam or includes a phase imprint on a beam cross section of the input laser beam.

For example, the beam splitting element is designed as a 3D beam splitting element or includes a 3D beam splitting element.

For example, the beam splitting element includes multiple components and/or functionalities. It can be provided that the beam splitting element comprises both a 3D beam splitting element and a polarization beam splitting element.

Provision can be made for the input laser beam to be split up exclusively by impressing phases on the beam cross section of the input laser beam.

In particular, the phase is impressed in the transverse direction of the input laser beam. The transverse direction lies in a plane oriented perpendicularly to the beam propagation direction of the input laser beam.

Alternatively or additionally, it can be provided that the input laser beam is split by means of the beam splitting element by polarization beam splitting or includes polarization beam splitting. For example, mutually adjacent focus elements can then each be formed with different states of polarization. In this way, in particular, interference between focus elements that are adjacent to one another can be prevented. As a result, mutually adjacent focus elements can be arranged, for example, at a particularly small distance from one another.

In principle, it is possible for the input laser beam to be split both by means of phase imprinting and by means of polarization beam splitting.

It can be advantageous if the machining line is designed to be spatially continuous over a thickness of the material of the workpiece and/or over a thickness of a workpiece segment to be separated from the workpiece. It For example, the workpiece can be divided into two parts or a workpiece segment can be separated from the workpiece.

In particular, a shape of the processing line corresponds to a shape and/or cross-sectional shape and in particular to a target shape and/or target cross-sectional shape of a parting surface to be formed or formed by cutting the material. An edge geometry and/or a cross-sectional geometry and in particular a desired edge geometry and/or desired cross-sectional geometry of a parting surface created by separation of the material can thus be defined by means of the machining line.

For example, the at least one processing line has a total length of between 50 μm and 5000 μm and preferably between 100 μm and 1000 μm. As a result, workpieces with a thickness in the stated range can be machined and, in particular, separated.

The material of the workpiece has, for example, a thickness between 50 μm and 5000 μm and preferably between 100 μm and 1000 μm, for example approximately 500 μm.

The processing line is not necessarily designed to be spatially connected, but can have various spatially separate sections. In particular, the processing line can have gaps and/or interruptions where no focus elements are arranged.

In particular, the processing line is or includes a connecting line between mutually adjacent focus elements.

In particular, it can be provided that the processing line is straight at least in sections and/or that the processing line is curved at least in sections and/or is a curve.

By executing the processing line as a curve, rounded segments can be separated from the workpiece, for example. This allows rounded edges to be created, for example. When the machining line is designed as a curve, the machining line is assigned, for example, a specific setting angle range which the machining line has in relation to the outside of the workpiece.

In particular, it can be provided that a distance between mutually adjacent focus elements has a distance component that differs from zero and is oriented parallel to a thickness direction of the workpiece. In particular, the respective spacing of all adjacent focus elements, which are provided for laser processing of the workpiece, has a non-zero spacing component, which is oriented parallel to the thickness direction of the workpiece.

In particular, the distance component parallel to the thickness direction has a value which is greater than zero in absolute terms.

A neighboring focus element is to be understood, in particular, as a nearest neighbor of a specific focus element.

The thickness direction of the workpiece is to be understood in particular as a direction which is oriented transversely and in particular perpendicularly to an outside of the workpiece, through which the focus elements and/or a laser beam for forming the focus elements are coupled into the material.

In particular, it can be provided that the distance between the mutually adjacent focus elements has a distance component that differs from zero and is oriented parallel to a beam propagation direction of a laser beam from which the focus elements are formed. In particular, the respective spacing of all adjacent focus elements, which are provided for laser processing of the workpiece, has this non-zero spacing component.

It can be favorable if an angle of attack between the processing line and an outside of the workpiece through which the focus elements enter the Material of the workpiece are coupled, at least in sections is at least 1 ° and / or at most 90 °. Depending on the choice of the angle of attack, the workpiece can be cut vertically, for example, or the workpiece can be chamfered at a certain angle.

The fact that the machining line has a specific angle of attack or angle of attack range at least in sections is to be understood in particular as meaning that the machining line has at least one section with this angle of attack or angle of attack range.

In particular, the angle of attack can be at least 10° and/or at most 80°, preferably at least 30° and/or at most 60°, particularly preferably at least 40° and/or at most 50°.

In particular, it can be provided that the angle of attack of the machining line is constant at least in sections, and/or that the machining line has several sections with different angles of attack.

For example, the processing line has at least two sections with different angles of attack. In particular, at least one etching access can then be provided, which opens into the processing line and/or meets the processing line at a transition between the first section and the second section.

The material modifications introduced into transparent materials by ultrashort laser pulses are divided into three different classes, see K. Itoh et al. "Ultrafast Processes for Bulk Modification of Transparent Materials" MRS Bulletin, vol. 31 p.620 (2006): Type I is an isotropic refractive index change; Type II is a birefringent refractive index change; and Type III is a so-called void. The material modification produced depends on the laser parameter n of the laser beam from which the focus element is formed, such as the pulse duration, the wavelength, the pulse energy and the repetition frequency of the laser laser beam, and on the material properties, such as the electronic structure and the thermal expansion coefficient, among others, as well as on the numerical aperture (NA) of the focusing.

The type I isotropic refractive index changes are attributed to localized melting caused by the laser pulses and rapid resolidification of the transparent material. For example, with fused silica, the density and refractive index of the material is higher when the fused silica is rapidly cooled from a higher temperature. So if the material in the focus volume melts and then cools down quickly, the quartz glass has a higher refractive index in the areas of material modification than in the unmodified areas.

The type II birefringent refractive index changes can arise, for example, as a result of interference between the ultrashort laser pulse and the electric field of the plasma generated by the laser pulses. This interference leads to periodic modulations in the electron plasma density, which leads to a birefringent property, i.e. direction-dependent refractive indices, of the transparent material when it solidifies. A type II modification is also accompanied, for example, by the formation of so-called nanogratings.

The voids (cavities) of the type III modifications can be generated with a high laser pulse energy, for example. The formation of the voids is attributed to an explosive expansion of highly excited, vaporized material from the focus volume into the surrounding material. This process is also known as a micro-explosion. Because this expansion occurs within the bulk of the material, the microblast leaves behind a less dense or hollow core (the void), or submicron or atomic-scale microscopic defect, surrounded by a densified shell of material. Due to the compression at the impact front of the microexplosion, stresses arise in the transparent material, which can lead to spontaneous cracking or can promote cracking. In particular, the formation of voids can also be associated with type I and type II modifications. For example, Type I and Type II modifications can arise in the less stressed areas around the introduced laser pulses. Therefore, if a type III modification is introduced, then in any case a less dense or hollow core or a defect is present. For example, in a type III modification of sapphire, the microexplosion does not create a cavity, but rather an area of lower density. Due to the material stresses that occur in a type III modification, such a modification is often accompanied by cracking or at least promotes it. The formation of type I and type II modifications cannot be completely prevented or avoided when introducing type III modifications. Finding "pure" type III modifications is therefore not likely.

At high repetition rates of the laser beam, the material cannot cool down completely between the pulses, so that cumulative effects of the introduced heat from pulse to pulse can influence the material modification. For example, the repetition frequency of the laser beam can be higher than the reciprocal of the heat diffusion time of the material, so that heat accumulation can take place in the focus elements by successive absorption of laser energy until the melting temperature of the material is reached. In addition, a larger area than the focus elements can be melted due to the thermal transport of the heat energy into the areas surrounding the focus elements. After the introduction of ultra-short laser pulses, the heated material cools rapidly, so that the density and other structural properties of the high-temperature state in the material are effectively frozen.

It can be advantageous if material modifications are formed in the material as a result of the material being subjected to the focus elements, the material modifications being type III material modifications and/or the material modifications being accompanied by cracking of the material. In particular, a separation of the material can be realized by means of these material modifications. It can be favorable if material modifications are formed in the material by subjecting the material to the focus elements, the material modifications being type I and/or type II material modifications, and/or the material modifications being associated with a change in a refractive index of the material. In particular, a separation of the material can be realized by means of these material modifications.

In particular, it can be provided that the focus elements are moved in a feed direction relative to the material of the workpiece. The focus elements preferably lie at least approximately in a plane which is oriented, in particular, perpendicularly to the feed direction.

The movement of the focus elements relative to the material of the workpiece forms a machining surface that corresponds to the machining line, along which material modifications are arranged and/or along which the material of the workpiece can be separated. Furthermore, as a result, the etching access is flat in the feed direction, so that it extends in particular along a surface and/or plane oriented parallel to the feed direction.

A transparent material is to be understood in particular as a material that is transparent to the input laser beam and/or a laser beam from which the focus elements are formed. In particular, this means a material through which at least 70% and in particular at least 80% and in particular at least 90% of a laser energy of the input laser beam and/or the laser beam from which the focus elements are formed is transmitted.

In particular, the input laser beam and/or a laser beam from which the focus elements are formed is a pulsed laser beam and in particular an ultra-short pulse laser beam. By impinging the material with the focus elements, laser pulses in particular and in particular ultra-short laser pulses are thereby introduced into the material. In particular, the input laser beam and/or a laser beam from which the focus elements are formed has a diffractive beam profile and/or a Gaussian beam profile.

For example, a wavelength of the input laser beam and/or of the laser beam from which the focus elements are formed is at least 300 nm and/or at most 1500 nm. For example, the wavelength is 515 nm or 1030 nm.

In particular, the input laser beam and/or the laser beam from which the focus elements are formed has an average power of at least IW to 1 kW. For example, the laser beam includes pulses with a pulse energy of at least 10 pJ and/or at most 50 mJ. It can be provided that the laser beam comprises individual pulses or bursts, the bursts having 2 to 20 sub-pulses and in particular a time interval of approximately 20 ns.

In particular, a focus element is to be understood as meaning a focused radiation area of the input laser beam, which in particular has a specific spatial extent. To determine the spatial dimensions of a specific focus element, such as a diameter of the focus element, only intensity values that are above a specific intensity threshold are considered. The intensity threshold is selected here, for example, in such a way that values lying below this intensity threshold have such a low intensity that they are no longer relevant for an interaction with the material for the formation of material modifications. For example, the intensity threshold is 50% of a global maximum intensity of the focus element.

In particular, a spatial interaction area is assigned to a specific focus element, in which the focus element interacts with the material of the workpiece when it is introduced into it. In particular, the focus element interacts with the material in this interaction region by non-linear absorption. In particular, it can be provided that the respective focus elements according to the above definition have a maximum spatial extent of at least 0.5 μm and/or at most 60 μm, preferably at least 2 μm and/or at most 10 μm. In particular, a maximum spatial extent of an interaction region associated with a specific focus element with the material of the workpiece is at least 0.5 μm and/or at most 60 μm, and preferably at least 2 μm and/or at most 10 μm.

The maximum spatial extent of a specific focus element is to be understood in particular as the greatest spatial extent of the focus element in any spatial direction.

In particular, a respective maximum spatial extent of the focus elements is less than 20% and preferably less than 10% and particularly preferably less than 5% of a thickness of the material.

In particular, the focus elements introduced into the material interact with the material through non-linear absorption. In particular, material modifications due to non-linear absorption with the material are formed by means of the focus elements.

In particular, the focus elements have a diffractive beam profile. In particular, the focus elements are designed to be diffraction-limited. For example, one or more focus elements have a Gaussian shape and/or a Gaussian intensity profile.

In principle, it is also possible for one or more focus elements to have a Bessel-like shape and/or a quasi-non-diffracting intensity profile and/or a Bessel-like intensity profile.

The focus element(s) provided to form the material modifications along the processing line and the focus element(s) provided to form the at least one etching access The focus element/focus elements provided can, but do not necessarily have to, have the same shape and/or the same intensity profile.

In particular, the terms “at least approximately” or “approximately” generally mean a deviation of at most 10%. Unless otherwise stated, the terms “at least approximately” or “approximately” mean in particular that an actual value and/or distance and/or angle deviates by no more than 10% from an ideal value and/or distance and/or angle .

The following description of preferred embodiments serves to explain the invention in more detail in conjunction with the drawings. Show it:

1 shows a schematic representation of an exemplary embodiment of a device for laser machining a workpiece;

2 shows a schematic cross-sectional illustration of a section of a material of the workpiece, in which a separation of the material is provided along a processing line;

FIG. 3 shows a schematic cross-sectional illustration of the section according to FIG. 2, wherein the material for laser processing is subjected to a plurality of focus elements;

4 shows a schematic cross-sectional representation of a section of the material in which material modifications, which are associated with cracking of the material, were produced by subjecting the workpiece to focus elements;

5 shows a cross-sectional representation of a simulated intensity distribution of focus elements for laser processing of the workpiece;

6a shows a schematic perspective illustration of a workpiece with material modifications formed thereon; FIG. 6b shows a schematic perspective representation of two workpiece segments which are formed by separating the workpiece according to FIG. 6a.

Identical or functionally equivalent elements are provided with the same reference symbols in all figures.

An exemplary embodiment of a device for laser machining a workpiece is shown in FIG. 1 and is denoted by 100 there. The device 100 can be used to produce localized material modifications in a material 102 of the workpiece 104, such as defects in the submicrometer range or at the atomic level, which result in a material weakening. The workpiece 104 can be separated at these material modifications. For example, a workpiece segment can be separated from the workpiece 104 by means of the material modifications produced.

In particular, the device 100 can be used to introduce material modifications into the material 102 at an angle of attack, so that an edge region of the workpiece 104 can be chamfered or beveled by separating a corresponding workpiece segment from the workpiece 104 .

The device comprises a beam splitting element 106 into which an input laser beam 108 is coupled. This input laser beam 108 is provided by a laser source 110, for example. For example, the input laser beam 108 is a pulsed laser beam and/or an ultrashort pulse laser beam.

The input laser beam 108 is to be understood, in particular, as a bundle of rays which comprises a plurality of beams, which in particular run parallel. The input laser beam 108 has, in particular, a transverse beam cross section 112 and/or a transverse beam extension, with which the input laser beam 108 impinges on the beam splitting element 106 . The input laser beam 108 impinging on the beam splitting element 106 has, in particular, at least approximately flat wave fronts 114 .

The input laser beam 108 is divided into a plurality of partial beams 116 and/or partial beam bundles by means of the beam splitting element 106 . In the example shown in FIG. 1, two different partial beams 116a and 116b are indicated.

The partial beams 116 or partial beam bundles coupled out of the beam splitting element 106 have in particular a divergent beam profile. In particular, the beam splitting element 106 is designed as a far-field beam-shaping element.

In order to focus the partial beams 116 coupled out of the beam splitting element 106, the device 100 comprises focusing optics 118 into which the partial beams 116 are coupled. The focusing optics 118 have, for example, one or more lens elements. For example, the focusing optics 118 are designed as a microscope objective.

For example, the beam splitting element 106 is arranged at least approximately in a rear focal plane of the focusing optics 118 .

The focusing optics 118 has a focal length of between 5 mm and 50 mm, for example.

In particular, partial beams 116 that are different from one another impinge on the focusing optics 118 with a spatial offset and/or angular offset.

The partial beams 116 are focused by means of the focusing optics 118, so that a plurality of focus elements 120 are formed, which are each arranged at different spatial positions. In principle, it is possible for focus elements that are different from one another and/or that are adjacent to one another to spatially overlap in sections. For example, one or more partial beams 116 and/or partial beams of rays are assigned to a specific focus element 120 . For example, a respective focus element 120 is formed by focusing one or more partial beams 116 and/or partial beams of rays.

A focus element 120 is to be understood in particular as a focussed radiation area, such as a focus spot, a focus point or a focus line. In particular, the focus elements 120 each have a specific geometric shape and/or a specific intensity profile, the geometric shape being understood to mean, for example, a spatial shape and/or spatial extent of the respective focus element 120 .

The geometric shape and/or the intensity profile of a specific focus element 120 is referred to below as the focus distribution 121 of the focus element 120 . The focus distribution 121 is a property of the respective focus elements 120 and describes their shape and/or intensity profile. In particular, a plurality of focus elements 120 or all focus elements 120 formed have the same focus distribution.

The focus distribution of the focus elements 120 formed is defined by the input laser beam 108, the focus elements 120 being formed as a result of its division by means of the beam splitting element 106. If the input laser beam 108 were to be focused before it is coupled into the beam splitting element 106, a single focus element would be formed with the focus distribution assigned to the input laser beam 108, for example.

For example, the input laser beam 108 has a Gaussian beam profile when it is provided, for example, by means of the laser source 110 . In this case, by focusing the input laser beam 108, a focus element would be formed which has a focus distribution with a Gaussian shape and/or a Gaussian intensity profile. Alternatively, it can be provided, for example, that input laser beam 108 is assigned a quasi-non-diffractive and/or Bessel-like beam profile, so that focusing input laser beam 108 would form a focus element that has a focus distribution with a quasi-non-diffractive or Bessel-like Shape and/or quasi-non-diffracting or Bessel-like intensity profile.

The focus distribution of the input laser beam 108 is assigned to the partial beams 116 and/or partial beam bundles formed by splitting the input laser beam 108 by means of the beam splitting element 106 in such a way that the focus elements 120 are formed with this focus distribution and/or with a focus distribution based on this focus distribution by focusing the partial beams 116 .

In the example shown in FIG. 1, the input laser beam 108 has a Gaussian beam profile, i. H. a focus distribution with a Gaussian shape and/or Gaussian intensity profile is assigned to the input laser beam 108 . The focus elements 120 then each have, for example, the focus distribution 121 with this Gaussian shape and/or this Gaussian intensity profile or with a shape or intensity profile based on this Gaussian shape and/or this Gaussian intensity profile (cf. Fig. 5).

If, for example, a Bessel-like beam profile is assigned to the input laser beam 108, the focus elements 120 designed for laser processing of the workpiece 104 each have a focus distribution 121 with this Bessel-like beam profile or with a beam profile based on this Bessel-like profile. As a result, the focus elements 120 can each be formed, for example, with a focus distribution which has an elongate shape and/or an elongate intensity profile.

It can be provided that the device 100 has a beam shaping device 122 for beam shaping of the input laser beam 108 (indicated in FIG. 1). For example, this beam shaping device is 122 with respect to a beam propagation direction 124 of the input laser beam 108 is arranged in front of the beam splitting element 106 and/or arranged between the laser source 110 and the beam splitting element 106 .

A beam propagation direction is to be understood in particular as a main beam propagation direction and/or a mean propagation direction of laser beams.

In particular, a specific focus distribution and/or a specific beam profile can be assigned to the input laser beam 108 by means of the beam shaping device 122 . In particular, the focus distribution 121 of the focus elements 120 can be defined by means of the beam shaping device 122 .

The beam shaping device 122 can be set up, for example, to form a laser beam with a quasi-non-diffractive and/or Bessel-like beam profile from a laser beam with a Gaussian beam profile. The input laser beam 108 coupled into the beam splitting element 106 then has the quasi-non-diffractive and/or Bessel-like beam profile. Correspondingly, the focus elements 120 then also have this quasi-non-diffractive and/or Bessel-like beam profile or a beam profile based on this beam profile.

For example, the beam shaping device 122 can comprise an axicon element in order to form laser beams with a quasi-non-diffractive and/or Bessel-like beam profile. One or more lens elements (not shown) can then be provided, for example, for coupling beams coupled out of the beam-shaping device 122 into the beam-splitting element 106 .

With regard to the definition and realization of quasi-non-diffracting and/or Bessel-like beams, reference is made to the book "Structured Light Fields: Applications in Optical Trapping, Manipulation and Organisation", M. Wördemann, Springer Science & Business Media (2012), ISBN 978 -3-642-29322-1 and to the scientific papers "Bessel-like optical beams with arbitrary trajectories" by I. Chremmos et al., Optics Letters, Vol. 23 , 1 December 2012 and "Generalized axicon-based generation of nondiffracting beams" by K. Chen et al., arXiv: 1911.03103vl [physics. optics], November 8, 2019.

By splitting the beam by means of the beam splitting element 106, the focus elements 120 are in particular each formed identically to one another and/or each formed as copies of one another.

A schematic cross-section of workpiece 104 and material 102 is shown in Figures 2-4, with a cross-sectional plane oriented parallel to a thickness direction 126 and/or depth direction of the workpiece (in the example shown, thickness direction 126 is parallel to the z-direction oriented).

It is provided that the workpiece 104 can be separated or is separated along a predefined processing line 128 after the laser processing has taken place using the device 100 . The machining line 128 corresponds to a cross-sectional geometry with which the workpiece 104 is intended to be separated.

To carry out the laser processing, the focus elements 120 are introduced into the material 102 of the workpiece 104 (FIG. 3). Provision is made for the focus elements 120 introduced into the material 102 of the workpiece 104 to be moved in a feed direction 130 relative to the material 102 . A movement of the focus elements 120 relative to the material 102 takes place in the feed direction 130, in particular at a defined feed rate.

Each of the focus elements 120 formed is assigned a specific local position xo, zo, at which a respective focus element 120 is arranged with respect to the material 102 of the workpiece 104 . For example, the local position of a focus element 120 is to be understood as meaning the position of its spatial center point and/or center of gravity. In particular, the local positions xo, zo of the respective focus elements 120 lie in a plane oriented perpendicularly to the feed direction 130, with in particular all focus elements 120 designed for laser processing of the workpiece 104 lying in this plane.

In particular, a specific intensity I is assigned to each of the focus elements 120 formed.

The local position xo, zo and in particular also the intensity I of the respective focus elements 120 can be adjusted by means of the beam splitting element 106 .

In particular, a respective distance d and/or a respective spatial offset between adjacent focus elements 120 can be set by means of the beam splitting element 106 . A distance direction of the distance d adjustable by means of the beam splitting element 106 preferably lies in a plane which is oriented transversely and in particular perpendicularly to the feed direction 130 . For example, the distance d can be set component by component in two spatial directions by means of the beam splitting element 106, which span the plane mentioned or lie in the plane mentioned (x-direction and z-direction in the example shown in FIG. 3).

The feed direction 130 is oriented transversely and in particular perpendicularly to the thickness direction 126 of the workpiece 104 .

The beam splitting element 106 is preferably designed as a 3D beam splitting element or comprises a 3D beam splitting element. As a result, the focus elements 120 can be formed, for example, in such a way that they are identical to one another and/or that they each represent copies of one another.

With regard to the technical implementation and properties of the beam splitting element 106 designed as a 3D beam splitting element, reference is made to the scientific publication "Structured light for ultrafast laser micro- and nanoprocessing" by D. Flamm et al., arXiv:2012.10119vl [physics. optics], December 18, 2020. This is expressly and fully referred to. To carry out the beam splitting, in one embodiment of the beam splitting element 106 in which the beam splitting element 106 is designed as a 3D beam splitting element, for example, a defined transverse phase distribution is impressed on the transverse beam cross section 112 of the input laser beam 108 . A transverse beam cross section or a transverse phase distribution is to be understood in particular as a beam cross section or a phase distribution in a plane oriented transversely and in particular perpendicularly to the beam propagation direction 124 of the input laser beam 108 .

The spaced-apart focus elements 120 are formed by interference of the focused sub-beams 116, which can be, for example, constructive interference, destructive interference, or incidents thereof, such as partially constructive or partially destructive interference.

To form the focus elements 120 at the respective position xo, zo and/or with the respective distance d, the phase distribution imposed by the beam splitting element 106 has a specific optical grating component and/or optical lens component for each focus element 120.

Due to the optical lattice component, after the partial beams 116 have been focused, there is a corresponding spatial offset of the focus elements 120 formed in a first spatial direction, e.g. in the x-direction. Due to the optical lens component, partial beams 116 or partial beams of rays impinge on the focusing optics 118 at different angles or different convergence or divergence, which results in a spatial offset in a second spatial direction, e.g. in the z-direction, after focusing has taken place.

The local positions xo, zo can consequently be defined by appropriate design of the beam splitting element 106 or the phase distribution applied by means of the beam splitting element. The intensity I of the respective focus elements 120 is determined by the phase positions of the focused partial beams 116 relative to one another. These phase angles can be defined by the stated optical grating components and optical lens components. When designing the beam splitting element 106, the phase angles of the focused partial beams 116 can be selected relative to one another such that the focus elements 120 each have a desired intensity.

As an alternative or in addition to the variants of the beam splitting element 106 described above, it can be provided that the beam splitting element 106 is designed as a polarization beam splitting element or comprises a polarization beam splitting element. In this case, the beam splitting element 106 is used to carry out a polarization beam splitting of the input laser beam 108 into beams which each have one of at least two different polarization states.

In particular, the stated polarization states are to be understood as meaning linear polarization states, with two different polarization states being provided, for example, and/or polarization states oriented perpendicularly to one another being provided.

In particular, the polarization states are such that an electric field is oriented in a plane perpendicular to the beam propagation direction of the polarized beams (transverse electric).

For polarization beam splitting, the beam splitting element 106 comprises, for example, a birefringent lens element and/or a birefringent wedge element. The birefringent lens element and/or the birefringent wedge element are made of, for example, a quartz crystal or comprise a quartz crystal.

With regard to the functioning and design of the beam splitting element 106 as or with a polarization beam splitting element, reference is made to the German patent application with file number 10 2020 207 715.0 (filing date: June 22, 2020) by the same applicant and to DE 10 2019 217 577 A1. In particular, the partial beams 116 can be formed with different states of polarization by means of the beam splitting element 106 . By focusing these partial beams 116 using the focusing optics 118, the focus elements 120 can be formed, for example, from beams with a specific polarization state. As a result, a specific polarization state can be assigned to the focus elements 120 in each case.

In particular, it can be provided that the focus elements 120 are arranged and formed by polarization beam splitting by means of the beam splitting element 106 such that mutually adjacent focus elements 120 each have different polarization states.

The coupling of the focus elements 120 into the material 102 takes place, for example, through a first outer side 132 of the material 102 of the workpiece 104 . A second outside 134 of the material 102 of the workpiece 104 is arranged at a distance from the first outside 132 in the thickness direction 126 of the workpiece 104 , for example.

The first outside 132 and the second outside 134 are oriented at least approximately parallel to one another, for example. For example, the workpiece 104 is plate-shaped and/or panel-shaped.

The material 102 of the workpiece 104 has an at least approximately constant thickness D in the thickness direction 126, for example.

The focus elements 120 formed are arranged along the processing line 128 . The respective distances d and intensities I of the focus elements 120 arranged along the processing line 128 are selected such that material modifications 138 are formed by impinging the material 102 with these focus elements 120 (Fig. 4), which separate the material 102 along this processing line 128 and /or enable a processing surface corresponding to this processing line 128. In particular, the distances d and intensities I are selected such that the material 102 can be separated along the processing line 128 by etching using at least one wet-chemical solution. In the representations according to FIGS. 3 and 4, the focus elements or the material modifications are only shown schematically in terms of number, geometry, extent and arrangement.

In particular, it can be provided that the processing line 128 extends between the first outer side 132 and the second outer side 134 and in particular continuously and/or without interruption between the first outer side 132 and the second outer side 134 of the workpiece 104 .

It can be provided that the processing line 128 has several different sections 140 . For example, in the example shown in Fig. 3, the processing line 128 has a first section 140a, a second section 140b and a third section 140c, with the second section 140b adjoining the first section 140a and the third section 140c with respect to the thickness direction 126 connects to the second section 140b.

The processing line 128 is not necessarily designed to be continuous and/or differentiable. For example, the processing line 128 may have discontinuities. Provision can be made for the processing line 128 to have interruptions and/or gaps at which, in particular, no focus elements 120 are arranged.

The processing line 128 and/or different sections 140 of the processing line 128 can be formed, for example, as a straight line or a curve.

The respective distance d between the focus elements 120 provided for the laser processing of the workpiece 104 can be selected differently for different focus elements 120 and/or different pairs of focus elements 120 . In principle, however, it is also possible for the respective distance d to be identical for all focus elements 120 provided for laser processing of the workpiece 104 . In particular, a distance component d _z of the distance d oriented parallel to the thickness direction 126 of the material 102 is different from zero for all focus elements 120 and/or for all pairs of mutually adjacent focus elements 120 . In particular, all adjacent focus elements 120 are spaced apart in the thickness direction 126 by a distance component _dz that is different from zero.

In addition, the machining line 128 and/or the respective sections 140 of the machining line 128 are assigned a specific angle of incidence o and/or the angle of attack range, which the machining line 128 or the respective section 140 encloses with the first outer side 132 of the workpiece 104.

In the exemplary embodiment shown, the angle of incidence α of the first section 140a and of the third section 140c is 45° and that of the second section 140b is 90°.

The material modifications 138 formed in the material 102 by impacting and/or introducing the focus elements 120 are arranged in the material 102 at localized local positions. The local positions of the material modifications 138 correspond at least approximately to the local positions xo, zo of the focus elements 120, by means of which the material modifications 138 were formed in each case. By suitably selecting processing parameters, such as the respective distances d between the focus elements 120, their respective intensities I, the feed rate oriented in the feed direction 130, and the laser parameters of the input laser beam 108, the material modifications 138 can be formed, for example, as type III modifications, which for example, are associated with a spontaneous formation of cracks 142 in the material 102 of the workpiece 104 . In particular, cracks 142 are formed between adjacent material modifications 138 .

Alternatively, it is also possible by appropriate choice of

Machining parameters to form the material modifications 138 as Type I and/or Type II modifications, which involve heat accumulation in the material 102 and/or with a change in a refractive index of the material 102. The formation of the material modifications 138 as Type I and/or Type II modifications is associated with heat accumulation in the material 102 of the workpiece 104 . In particular, in order to form these material modifications 138, the respective distance d between the focus elements 120 is selected to be so small that this accumulation of heat occurs when the material 102 is acted upon by the focus elements.

Provision is made for the material 102 of the workpiece 104 to be separated along the processing line 128 or along a processing surface corresponding to this processing line 128 by etching using at least one wet-chemical solution.

For example, after the material modifications 138 have been formed, the workpiece 104 is introduced into the wet-chemical solution for etching, with the wet-chemical solution passing through the first outer side 132 and/or the second outer side 134 into the areas marked on the processing line 128 or

Machining surface trained material modifications 138 and possibly cracks 142 penetrates into the material 102.

In the present case, one or more etching accesses 144 are formed on the material 102 in order to improve the supply of the wet-chemical solution. In the example shown in FIG. 3 there is a first etch access 144a and a second etch access 144b.

Etching access 144 is designed to allow wet-chemical solution from one of the outer sides 132, 134 of the workpiece 104 (e.g. the first outer side 132 or the second outer side 134) to the processing line 128 and in particular to the material modifications 138 and/or cracks 142 associated with the processing line 128 to supply In particular, the etching access 144 is designed in such a way that the wet-chemical solution can be carried out and/or passed through it.

In particular, the etching access 144 has a channel-like and/or line-like cross section (cf. FIGS. 3 and 4). A cross-sectional plane of this Cross-section is oriented, for example, transversely and in particular perpendicularly to at least one of the outer sides 132, 134, and/or oriented perpendicularly to the feed direction 130, for example.

The etching access 144 is oriented transversely and in particular perpendicularly to the respective outer side 132 or 134 . In particular, the etching access 144 has a longitudinal central axis 146 with respect to its cross section, which is oriented transversely and in particular perpendicularly to the respective outer side 132 or 134 .

The etching access 144 extends flatly along a surface and/or plane oriented parallel to the feed direction 130 (in the example shown in FIG. 4 flatly in a plane oriented parallel to the y-direction, i.e. along a plane running into the plane of the paper). In particular, the longitudinal center axis 146 lies in this surface and/or plane.

The etching access 144 runs from the respective outer side 132, 134 into the interior of the material 102. In particular, the etching access 144 extends with respect to the thickness direction 126 from the respective outer side 132 or 134 to a penetration depth T. For example, the penetration depth T is at least 1% of the Thickness D of material 102.

For example, the etch access 144 has an inlet 148 and an outlet 150 for wet chemical solution. The entrance is positioned on the respective outside 132, 134 of the workpiece. The exit 150 is located inside the material 102 .

In particular, the etching access 144 at the exit 150 opens into the processing line 128 and/or into the material modifications 138 and/or cracks 142 associated with the processing line 128 .

In the example shown in FIG. 3 , etch access 144a opens into processing line 128 at a transition between second section 140b and third section 140c, and etch access 144b at a transition between first section 140a and second section 140b. The etching access 144 is formed in particular by subjecting the material 102 to focus elements 120′. The focus elements 120′ are in particular of the same design as the focus elements 120 described above, so that in this respect reference is made to their above description.

In particular, both the focus elements 120 and the focus elements 120 ′ are formed by means of the device 100 or by means of the beam splitting element 106 and the focusing optics 118 . In particular, the focus elements 120 and the focus elements 120' are formed at the same time and/or the material 102 is acted upon at the same time by the focus elements 120 and the focus elements 120'.

Material modifications 138' and/or cracks 142' are produced by subjecting the material 102 to the focus elements 120' in order to form the etching access 144.

The respective intensities I and/or distances d of the focus elements 120' are selected in particular such that the material modifications 138' and/or cracks 142' produced by means of these focus elements 120' form the etch access 144 in such a way that wet-chemical solution can be conducted through the etch access is possible.

5 shows a simulated intensity distribution of a plurality of focus elements 120, the distance d for these focus elements 120 being approximately 8.0 μm. In the grayscale representation shown, lighter areas represent higher intensities.

The laser processing of the workpiece 104 using the device 100 works as follows:

To carry out the laser processing, the material 102 of the workpiece 104 is acted upon by the focus elements 120, 120' and the focus elements 120, 120' are moved in the feed direction 130 relative to the workpiece 104 through its material 102. In the example shown, the focus elements 120, 120' are formed by beam shaping of the input laser beam 108. FIG. In this case, the material 102 is a material that is transparent to a wavelength of laser beams from which the focus elements 120, 120' are each formed, such as a glass material, for example.

Material modifications 138, 138' are formed in the material 102 by subjecting the material 102 to the focus elements 120, 120'.

The material modifications 138 formed by means of the focus elements 120 are arranged along the processing line 128 (cf. FIGS. 3 and 6a), which, for example, extends continuously over the entire thickness D of the material 102. The focus elements 120 or material modifications 138 associated with the processing line 128 define a cross-sectional geometry of the parting surface (FIG. 6b) that is created by later parting of the material.

The material modifications 138' formed by means of the focus elements 120' are arranged along the respective central longitudinal axis 146 of the associated etch access 144 (for example the etch access 144a and 144b). The focus elements 120' or material modifications 138' assigned to the respective central longitudinal axis 146 define a cross-sectional geometry of the etching access 144 to be formed.

The focus elements 120, 120' are moved along a predetermined trajectory 152 relative to the material 102, as a result of which material modifications 138, 138' are arranged in the material 102 in a planar manner. In the example shown in FIG. 6 a , trajectory 152 is oriented parallel to feed direction 130 .

By moving the focus elements 120 relative to the material 102 along the trajectory 152, a processing surface 154 corresponding to the processing line 128 is formed, on which the material modifications 138 are arranged. In particular, the processing line 128 lies in the corresponding processing area 154. Correspondingly, material modifications 138' are formed in the material 102 by moving the focus elements 120' relative to the material 102, said modifications being arranged on processing surfaces 154'. These processing surfaces 154' correspond to the respective longitudinal central axes 146 of the etching accesses 144. In particular, the respective longitudinal central axis 146 of a specific etching access 144 lies in the corresponding processing surface 154'.

In principle, the trajectory 152 can have rectilinear and curved sections. In the case of curved sections, the processing line 128 and/or the longitudinal center axes 146 are rotated during the laser processing in particular in such a way that they always lie in a plane oriented perpendicularly to the feed direction 130 . This can be implemented, for example, by appropriately rotating the beam splitting element 106 or by rotating the entire device 100 relative to the workpiece 104 .

A distance from material modifications 138, 138' that are adjacent in the feed direction 130 can be defined, for example, by setting a pulse duration of the input laser beam 108 and/or by setting the feed rate.

The material modifications 138 formed along the processing line 128 result in particular in a reduction in the strength of the material 102, the strength being reduced, for example, due to the cracks 142 formed.

The material modifications 138' and/or cracks 142' associated with the etching accesses 144 also result in a reduction in the strength of the material 102, so that penetration of etching liquid and/or passage of etching liquid is made possible.

In order to separate the material 102 along the processing line 128 and/or processing surface 154, a wet-chemical solution is applied to it. For this purpose, the material 102 is, for example, introduced partially or completely into an etching bath with the wet-chemical solution, this taking place in particular for a specific period of time and/or at a specific temperature. In particular, the etching can be carried out with the assistance of ultrasound. For example, the wet chemical solution can include KOH and/or NaOH.

The wet-chemical solution penetrates on the outer sides 132, 134 into the material modifications 138 and/or cracks 142 associated with the processing line 128 and then penetrates along the processing line 128 into an inner region 155 of the material 102. The inner region 155 is, in particular, a region of the material 102 that is spaced apart from the respective outer side 132, 134 parallel to the direction of thickness 126.

The wet-chemical solution also penetrates into the corresponding etching accesses 144 on the outer sides 132, 134 and also reaches the inner region 155 of the material 102 lying on the processing line 128 through these etching accesses 144.

The wet-chemical solution is guided into the inner area 155 lying on the processing line 128 by means of the etching accesses 144 . In the example shown, the wet-chemical solution is guided by means of the etching accesses 144 from the respective outside 132, 134 to the second section 140b of the processing line 128. In this way, an improved introduction of the wet-chemical solution into the inner area 155 lying on the processing line 128 can be achieved.

The material 102 on the processing surface 154 is separated into two workpiece segments 156a, 156b that are different from one another (FIG. 6b) by etching using the supplied wet-chemical solution.

In the example shown, the workpiece segment 156a is a scrap segment and/or a scrap segment. The etching accesses 144 are arranged on the workpiece segment 156a or comprised by the workpiece segment 156a.

Typically, the workpiece segment 156a, ie, the scrap segment, along the extent of the etch accesses 144, is also formed during the etching process separated. As a result, the workpiece segment 156a is in turn divided into a plurality of segments.

The workpiece segment 156b is a good piece segment and/or a useful segment. It has a parting surface 158 which has a shape that corresponds to the shape of the machining line 128 .

The material 102 of the workpiece 104 is quartz glass, for example.

For example, to form the material modifications 138 as type I and/or type II modifications, a laser beam from which the focus elements 120, 120' are formed has a wavelength of 1030 nm and a pulse duration of 1 ps. Furthermore, a numerical aperture assigned to the focusing optics 118 is 0.4 and a pulse energy assigned to a single focus element 120, 120' is 50 to 200 nJ.

For forming the material modifications 138, 138' as type III modifications, with otherwise the same parameters, the pulse energy assigned to a single focus element 120, 120' is 500 to 2000 nJ.

Reference numeral a Angle of attack d Distance d _z Distance component

D thickness

T penetration depth

Xo Position in x-direction

Zo position in y-direction

100 device

102 materials

104 workpiece

106 beam splitting element

108 input laser beam

110 laser source

112 beam cross-section

114 wavefront

116 partial beams

116a sub-beam

116b sub-beam

118 focusing optics

120 focus element

120' focus element

121 Focus distribution

122 beam shaping device

124 beam propagation direction

126 thickness direction

128 machining line

130 feed direction

132 first outside

134 second outside

138 material modification

138' material modification

140 section a first section b second section c third section crack 'crack etch access a first etch access b second etch access longitudinal center axis input output trajectory processing surface ' processing surface inner area a workpiece segment / waste segment b workpiece segment parting surface

Claims

Method for the laser processing of a workpiece (104), which has a transparent material (102), in which a plurality of focus elements (120, 120') are provided by means of an input laser beam (108) and the material (102) with the focus elements (120, 120 ') is applied, wherein by applying the focus elements (120) to the material (102), material modifications (138) are formed in the material (102) along a predetermined processing line (128), on which the material (102) is etched by means of at least a wet-chemical solution, and wherein at least one separate etching access (144) for supplying the at least one wet-chemical solution from an outside (132, 134) is created by applying the focus elements (120') to the material (102) of the workpiece (104) is formed into the machining line (128). Method according to Claim 1, characterized in that the at least one etching access (144) comprises material modifications (138') and/or cracks (142') formed in the material (102) of the workpiece (104) by means of the focus elements (120'). Method according to one of the preceding claims, characterized in that the at least one etching access (144) for supplying wet-chemical solution from the outside (132, 134) of the workpiece (104) into an inner region (155) of the workpiece (104) lying on the processing line (128). material (102), and/or that the at least one etching access (144) is an access that is spatially separate from the processing line (128) at least in sections, for supplying wet-chemical solution from the outside (132, 134) of the workpiece into one on the processing line (128) lying interior (155) of the material (102). Method according to one of the preceding claims, characterized in that the at least one etching access (144) comprises a passage and/or a channel for conducting the at least one wet-chemical solution. Method according to one of the preceding claims, characterized in that the at least one etching access (144) extends from an outside (132, 134) of the workpiece (104) to the processing line (128) and/or to the material modifications assigned to the processing line (128). (138). Method according to one of the preceding claims, characterized in that the at least one etching access (144) is formed in a region of the material (102) which after the workpiece (104) has been separated along the processing line (128) on or in a the waste segment (156a) formed during the separation of the workpiece (102). Method according to one of the preceding claims, characterized in that at least one etching access (144) is formed which has at least one of the following properties:

- The at least one etching access (144) extends with respect to a thickness direction (126) of the workpiece from an outside (132, 134) of the workpiece (104) to a penetration depth (T) of at least

1% and in particular at least 10% and in particular at least 20% of a thickness (D) of the material (102) of the workpiece (104);

- The at least one etching access (144) is oriented transversely and in particular perpendicularly to an outside (132, 134) of the workpiece (104); the at least one etching access (144) opens into the material (102) of the workpiece (104) in the machining line (128) and in particular in the material modifications associated with the machining line (128). (138) and/or cracks (142);

- The at least one etching access (144) is a tangential continuation of a section (140a, 140b, 140c) of the machining line (128) and/or opens tangentially into the machining line (128). Method according to one of the preceding claims, characterized in that the workpiece (104) is separated by etching using the at least one wet-chemical solution along the processing line (128) and/or along a processing surface (154) assigned to the processing line (128). Method according to one of the preceding claims, characterized in that the input laser beam (108) is divided into a plurality of partial beams (116) by means of a beam splitting element (106) and the focus elements (120, 120') are formed by focusing from the beam splitting element (106) coupled-out partial beams (116) are formed. Method according to one of the preceding claims, characterized in that the machining line (128) is spatially continuous over a thickness (D) of the material (102) of the workpiece (104) and/or over a thickness of a workpiece segment to be separated from the workpiece (104). is. Method according to one of the preceding claims, characterized in that a distance (d) between mutually adjacent focus elements (120, 120') has a non-zero distance component (d _z ) which is oriented parallel to a thickness direction (126) of the workpiece (104). is. Method according to one of the preceding claims, characterized in that a setting angle (o) between the processing line (128) and an outside (132, 134) of the workpiece (104) through which the focus elements (120, 120') into the material ( 102) of the workpiece (104) are coupled in, at least in sections is at least 1° and/or at most 90°. Method according to one of the preceding claims, characterized in that material modifications (138, 138') are formed in the material (102) by the action of the material (102) with the focus elements (120, 120'), the material modifications (138, 138') are type III material modifications, and/or wherein the material modifications (138, 138') are accompanied by cracking of the material (102). Method according to one of the preceding claims, characterized in that material modifications (138, 138') are formed in the material (102) by the action of the material (102) with the focus elements (120, 120'), the material modifications (138, 138') are type I and/or type II material modifications, and/or wherein the material modifications (138, 138') are accompanied by a change in a refractive index of the material. Method according to one of the preceding claims, characterized in that the focus elements (120, 120') are moved in a feed direction (130) relative to the material (102) of the workpiece (104), and in particular characterized in that the focus elements (120 , 120') lie at least approximately in a plane oriented perpendicularly to the feed direction (130).