EP4267338A1 - Procédé de séparation d'une pièce - Google Patents

Procédé de séparation d'une pièce

Info

Publication number
EP4267338A1
EP4267338A1 EP21836382.8A EP21836382A EP4267338A1 EP 4267338 A1 EP4267338 A1 EP 4267338A1 EP 21836382 A EP21836382 A EP 21836382A EP 4267338 A1 EP4267338 A1 EP 4267338A1
Authority
EP
European Patent Office
Prior art keywords
workpiece
laser
laser beam
removal
focal zone
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21836382.8A
Other languages
German (de)
English (en)
Inventor
Jonas Kleiner
Daniel FLAMM
Malte Kumkar
Michael Wendt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Trumpf Laser und Systemtechnik GmbH
Original Assignee
Trumpf Laser und Systemtechnik GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Trumpf Laser und Systemtechnik GmbH filed Critical Trumpf Laser und Systemtechnik GmbH
Publication of EP4267338A1 publication Critical patent/EP4267338A1/fr
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/38—Removing material by boring or cutting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/362—Laser etching
    • B23K26/364—Laser etching for making a groove or trench, e.g. for scribing a break initiation groove
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
    • B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
    • B23K26/0624—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses using ultrashort pulses, i.e. pulses of 1ns or less
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B33/00—Severing cooled glass
    • C03B33/02—Cutting or splitting sheet glass or ribbons; Apparatus or machines therefor
    • C03B33/0222—Scoring using a focussed radiation beam, e.g. laser
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
    • B23K2103/56—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26 semiconducting

Definitions

  • the present invention relates to a method for separating a workpiece by means of a laser beam comprising ultra-short laser pulses of an ultra-short-pulse laser.
  • a particular area of application for such laser radiation is cutting and processing in front of workpieces.
  • the laser beam is preferably introduced into the material with vertical incidence, since reflection losses on the surface of the material are then principally minimized.
  • the separation of materials with a high refractive index still represents an unsolved problem, in particular because the large difference in refractive index between the surrounding medium and the material of the workpiece leads to a strong aberration of the laser beam and thus no targeted energy deposition into the material can take place .
  • a method for separating a workpiece wherein material of the workpiece is removed along a separating line by means of a laser beam comprising ultra-short laser pulses of an ultra-short pulse laser, wherein the material of the workpiece is transparent to the wavelength of the laser beam and has a refractive index between 2.0 and 3, 5, preferably between 2.5 and 3.5, and the workpiece is separated in a separating step along a notch created by the removal of the material
  • the ultra-short pulse laser provides ultra-short laser pulses.
  • ultra-short can mean that the pulse length is between 500 picoseconds and 10 femtoseconds, for example, and in particular between 10 picoseconds and 100 femtoseconds.
  • the ultra-short laser pulses move in the beam propagation direction along the laser beam formed by them.
  • a transparent material is understood herein to mean a material that is essentially transparent to the wavelength of the laser beam of the ultrashort pulse laser.
  • the terms "material” and “transparent material” are used interchangeably here - the material mentioned here is therefore always to be understood as material that is transparent to the laser beam of the ultrashort pulse laser.
  • the laser beam falls at an angle from a surrounding medium, such as air, onto the surface of the transparent material, the laser beam is refracted at the angle of refraction.
  • the angle of incidence and the angle of refraction are linked to each other via the refractive index of the material of the workpiece and the surrounding medium by Snell's law of refraction.
  • Fresnel equations describe the polarization-dependent transmission and reflection behavior of the laser beam on the surface.
  • the intensity in the focus volume can result in non-linear absorption by, for example, multiphoton absorption and/or electron avalanche ionization processes.
  • This non-linear absorption leads to the generation of an electron-ion plasma, which can induce permanent structural changes in the material of the workpiece when it cools down.
  • Type I is an isotropic refractive index change
  • Type II is a birefringent refractive index change
  • type III is a so-called void or hollow space, which is produced by so-called micro-explosions.
  • the material modification produced depends on laser parameters such as the pulse duration, the wavelength, the pulse energy and the repetition frequency of the laser, on the material properties such as the electronic structure and the thermal expansion coefficient, as well as on the numerical aperture (NA) of the focussing.
  • NA numerical aperture
  • the voids (cavities) of the Type 111 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 micro-explosion leaves a less dense or hollow core (the void) 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.
  • a micro-explosion close to the surface can cause the
  • the material cannot cool down completely between the pulses, so that the heat present in the material increases from pulse to pulse.
  • the repetition frequency of the laser can be higher than the reciprocal of the heat diffusion time of the material, so heat accumulation can take place in the focal zone by successive absorption of laser energy until the melting temperature of the material is reached.
  • a larger area than the focus zone can be melted and vaporized, resulting in material removal.
  • the surface of the material is particularly heavily stressed, so that material is removed there.
  • the material is removed along a parting line with the effects mentioned above.
  • the parting line describes the line of impact of the laser beam on the surface of the workpiece.
  • the laser beam and the workpiece are shifted relative to one another at a feed rate, so that the laser pulses hit the surface of the workpiece at different locations as time progresses.
  • Displaceable relative to one another means here that both the laser beam can be displaced translationally relative to a stationary workpiece and that the workpiece can be displaced relative to the laser beam. It may also be the case that both the workpiece and the laser beam move. While the workpiece and laser beam are moved relative to each other, the ultra-short pulse laser emits laser pulses into the material of the workpiece at its repetition frequency.
  • the ultra-short laser pulses thus produce a material removal along the dividing line, so that the sum of the material removal results in a notch on the material surface.
  • the separating step may include a mechanical separation and/or an etching process and/or a thermal impact and/or a self-separation step.
  • a thermal impact can be, for example, heating of the material or the parting line.
  • the dividing line can be heated locally using a continuous wave CO2 laser, so that the material in the area of the introduced material weakness expands differently compared to the untreated or unmodified material.
  • thermal stress is implemented by means of a stream of hot air, or by baking on a hot plate, or by heating the material in an oven.
  • temperature gradients can also be applied in the separation step.
  • the cracks favored by the weakening of the material experience crack growth as a result, so that a continuous and non-jammed separating surface can form, through which the parts of the workpiece are separated from one another.
  • a mechanical separation can be produced by applying a tensile or bending stress, for example by applying a mechanical load to the parts of the workpiece separated by the dividing line.
  • a tensile stress can be applied when opposite forces act on the parts of the workpiece separated by the dividing line in the material plane at one force application point each pointing away from the dividing line. If the forces are not aligned parallel or antiparallel to one another, this can contribute to the development of bending stress.
  • a mechanical change can also be achieved by a pulsating effect on the part to be separated. For example, a lattice vibration can be generated in the material by an impact.
  • the deflection of the lattice atoms can also generate tensile and compressive stresses that can trigger cracking.
  • a method can also be referred to overall as a “write and break” method, in which a material is typically first scratched and then broken in a targeted manner along the defined dividing line.
  • the material can also be separated by etching with a wet-chemical solution, with the etching process preferentially attaching the material to the targeted weakening of the material.
  • etching process preferentially attaching the material to the targeted weakening of the material.
  • this results in parting of the workpiece along the parting line.
  • a so-called self-separation can also be carried out by targeted crack guidance through the orientation of the material removal in the material.
  • the formation of cracks from material removal to adjacent material removal enables the two parts of the workpiece to be separated over the entire surface without having to carry out a further separation step.
  • a notch can be formed on the upper side and/or the underside of the workpiece due to the removal of the material.
  • the laser beam can be introduced into the material in such a way that the upper side is in the focal zone of the laser beam.
  • an indentation is preferably introduced into the upper side of the material.
  • the laser beam can also be introduced into the material in such a way that the underside is in the focal zone of the laser beam.
  • an indentation is preferably introduced into the underside of the material.
  • the refractive index difference between the surrounding medium and the material of the workpiece can be greater than 1.5.
  • the refraction and reflection of the laser beam depend on the refractive indices of the surrounding medium and the material of the workpiece.
  • the surrounding medium does not have to be air, but can also be another material, for example glass.
  • the large difference in refractive index ensures that the refractive properties of the laser beam lead to material removal close to the surface during the transition from the surrounding medium to the material of the workpiece.
  • the material may contain or be silicon, or be silicon carbide SiC, or contain silicon carbide.
  • Silicon carbide is transparent in the visible and infrared spectral range, but has a refractive index of n>2.5. This leads to large reflection losses, although the material is transparent to the wavelength of the laser.
  • the workpiece can be a silicon wafer that is to be separated into chips.
  • the workpiece can have a thickness between 100 ⁇ m and 2000 ⁇ m, preferably 700 ⁇ m.
  • the workpiece can have a material thickness of 500 ⁇ m.
  • the workpiece can also comprise different material layers, that is to say have a layer system.
  • each layer of material can be transparent to the wavelength of the laser.
  • processed and treated wafer systems can also be separated using the process.
  • the material removal can be composed of a superficial material area removal and a localized depth of material removal, wherein the depth of the localized removal of material can have a width of more than 10 pm perpendicular to the parting line and a depth of more than 1 m.
  • a localized depth of material erosion has, for example, a diameter of a few micrometers, approximately between 1 m and 20 pm, while the depth of erosion is between 0.1 pm and 5 pm.
  • a surface removal of material has, for example, a diameter of 5 to 10 mm and an removal depth of 0 to 10 ⁇ m. As a result, the localized depth of material removal is limited to a small diameter at a greater depth of material, while the surface removal of material is limited to a large diameter and a small depth of material.
  • the diameter can be measured perpendicular to the parting line. In the case of separate material modifications, on the other hand, the diameter can also be the maximum diameter of the material removal.
  • the laser beam can be a non-diffracting laser beam and can have a focal zone that is elongated in the direction of beam propagation, preferably a focal zone that is elongated and variable in length in the direction of beam propagation.
  • Non-diffracting rays and/or Bessel-like rays are to be understood in particular as rays in which a transverse intensity distribution is propagation-invariant.
  • a transverse intensity distribution is essentially constant along a longitudinal direction and/or direction of propagation of the rays.
  • a transversal intensity distribution is to be understood as meaning an intensity distribution which lies in a plane oriented perpendicularly to the longitudinal direction and/or direction of propagation of the beams.
  • the focal zone is always understood to be that part of the intensity distribution of the laser beam that is greater than the modification threshold of the material. The word focal zone makes it clear that this part of the intensity distribution is provided in a targeted manner and that an intensity increase in the form of the intensity distribution is achieved by focusing.
  • non-diffracting laser beams have the advantage that they can have a focal zone that is elongated in the direction of beam propagation and that is significantly larger than the transverse dimensions of the focal zone.
  • a material removal that is elongated in the beam propagation direction can be generated in this way in order to ensure easy separation of the workpiece.
  • non-diffracting beams can be used to generate elliptical non-diffracting beams that have a non-radially symmetrical transverse focal zone.
  • elliptical quasi-non-diffracting rays have a main maximum that coincides with the center of the ray. The center of the ray is given by the place where the main axes of the ellipse intersect.
  • elliptical quasi non-diffracting beams can result from the superimposition of several intensity maxima, in which If only the envelope of the intensity maxima involved is elliptical. In particular, the individual intensity maxima do not have to have an elliptical intensity profile.
  • the diameter of the transverse focal zone can be less than 5 pm and/or the length of the longitudinal focal zone can be greater than 50 pm and/or the length of the longitudinal focal zone can be less than 1.2 times the material thickness.
  • the focal zone which is elongated in the direction of beam propagation, can penetrate the upper side of the workpiece and/or penetrate the lower side of the workpiece and/or penetrate both sides.
  • the material can be weakened in a targeted manner along the dividing line, so that a simple dividing can be realized by the dividing step.
  • a notch can preferably be produced in the top side. Because the elongated focal zone only penetrates the underside of the workpiece, a notch can preferably be produced on the underside. In particular, an elongated focal zone can also produce a notch on the top and bottom if the length of the elongated focal zone is longer than the material thickness.
  • the non-diffracting beam can be generated by an axicon, a diffractive optical element or a reflective or refractive free-form optical surface.
  • the beam shaping optics can be designed, for example, as a diffractive optical element (DOE), a free-form surface or an axicon or a microaxicon, or contain a combination of several of these components or functionalities. If the beam shaping optics forms a non-diffracting laser beam from the laser beam in front of the processing optics, then the Focusing of the processing optics, the insertion depth of the focus zone into the material can be determined. However, the beam-shaping optics can also be designed in such a way that the non-diffracting laser beam is only generated by imaging with the processing optics.
  • DOE diffractive optical element
  • a diffractive optical element is set up to influence the incident laser beam in one or more properties in two spatial dimensions.
  • a diffractive optical element is a fixed component that can be used to produce a specific non-diffractive laser beam from the incident laser beam.
  • a diffractive optical element is a specially shaped diffraction grating, whereby the incident laser beam is brought into the desired beam shape by the diffraction.
  • An axicon is a conically ground optical element that forms a non-diffracting laser beam from an incident Gaussian laser beam as it passes through.
  • the axicon has a cone angle a', which is calculated from the beam entry surface to the lateral surface of the cone.
  • the non-diffracting beam can be translated into the workpiece through a telescope.
  • a telescope is an optical structure or processing optics that enables the laser beam to be imaged or, together with the beam-shaping optics, makes a non-diffracting beam available in or on the material.
  • such a telescope can have an enlarging and/or reducing effect.
  • part of the optical functionality of the telescope can be integrated into the beam shaping optics.
  • the axicon can have a spherically ground rear side so that it combines beam shaping functionality with a lens effect.
  • Enlarging and/or reducing the laser beam or its transverse intensity distribution allows the laser beam intensity to be distributed over a large or small focal zone.
  • the intensity is adjusted by distributing the laser energy over a large or small area, so that it is possible to choose between modification types I, II, and III, in particular by enlarging and/or reducing the size.
  • an increased or decreased material removal can also be realized by increasing or reducing the non-radially symmetrical transverse intensity distribution will.
  • the optical system can be adapted to the given processing conditions by enlarging or reducing it, so that the device can be used more flexibly.
  • the pulse duration of the ultra-short laser pulses can be between 100 fs and 100 ns, preferably between 100 fs and 10 ps, and/or the average laser power can be between 1 W and 1 kW, preferably 50 W, and/or the wavelength can be between 300 nm and 1500 nm, preferably 1030 nm and/or the laser pulses can be individual laser pulses or be part of a laser burst, with a laser burst comprising between 1 and 20, preferably between 1 and 4 laser pulses and/or the repetition rate of the individual laser pulses and/or laser bursts can be 100 kHz and/or the pulse or burst energy can be between 10pJ and 50mJ.
  • the workpiece and the laser beam can be moved relative to one another at a feed rate, with the feed rate preferably being between 0.05 m/s and 5 m/s.
  • the material By moving the laser beam and the workpiece relative to each other, the material can be removed along the parting line.
  • an axle device is an XYZ table that can be translated along all spatial axes.
  • the axis device can also be rotated about certain axes, so that particularly high-quality round and/or curved separating lines can be produced.
  • the laser pulses or laser bursts can be introduced into the material at a spatially constant distance.
  • control electronics can regulate the pulse output depending on the relative position of the laser beam and the workpiece.
  • the feed device can have a position-resolving encoder that measures the position of the feed device and the laser beam. Based on the location information, the pulse output of a laser pulse can be triggered in the ultra-short pulse laser via a corresponding triggering system of the control electronics.
  • computer systems can also be used to implement the triggering of the pulse.
  • the locations of the laser pulse emission can be determined for the respective dividing line before the material is processed, so that an optimal distribution of the laser pulses along the dividing line is ensured.
  • Figure 1A, B is a schematic representation of the method
  • FIG. 2A, B, C shows a schematic representation of a separation step
  • FIG. 3A, B, C another schematic representation of the method
  • Figure 4A, B is a micrograph of an indented material
  • FIG. 5 shows another micrograph of an indented material
  • FIG. 6 shows a micrograph of a layer system separated by the method
  • Figure 7A,B is a schematic representation of a non-diffracting beam
  • FIG. 8 shows a schematic representation of the device for carrying out the method.
  • FIG. 9A, B another schematic representation of the device. Detailed description of preferred exemplary embodiments
  • FIG. 1A schematically shows a workpiece 1, the material of which has a high refractive index NM.
  • a laser beam 2 is brought onto the workpiece 1 and is focused in such a way that the partial laser beams 20 of the laser beam 2 fall on the upper side 10 of the workpiece 1 at an angle of incidence ⁇ .
  • the workpiece 1 is in particular transparent to the wavelength of the laser beam 2.
  • the laser beam 2, or its partial laser beams 20, is thus refracted according to the Fresnel formulas as a function of the refractive indices NM, NL and the angle of incidence ⁇ .
  • the refractive index difference between the material of the workpiece 1 and the surrounding medium is then greater than 1.5, so that the refractive effect is particularly large.
  • a non-diffracting laser beam 2 is formed, for example due to the conically tapering partial laser beams 20, which has a focal zone 22 that is elongated in the direction of beam propagation.
  • the elongated focal zone 22 penetrates the top 10 and the bottom 12 of the material of the workpiece 1.
  • the material of the workpiece 1 is vaporized by non-linear absorption effects, so that material is removed from the top 10 and the bottom 12.
  • the non-linear absorption effects result in a surface modification, for example deformation or material removal, on the upper side 10 so that there is no ideal non-diffracting beam 2 at least in the area close to the surface.
  • the non-diffracting laser beam 2 can then form, for example, due to self-healing effects.
  • the laser beam 2 is nevertheless described as a non-diffracting beam 2, taking such surface effects into account.
  • FIG. 1B shows that the material is removed along the parting line 3 .
  • the pulse duration of the ultra-short laser pulses can be between 100 fs and 100 ns, preferably between 100 fs and 10 ps, and/or the average laser power can be between 1 W and 1 kW, preferably 50 W, and/or the wavelength can be between 300 nm and 1500 nm, preferably 1030 nm and/or the laser pulses can be individual laser pulses or be part of a laser burst, with a laser burst comprising between 1 and 20, preferably between 1 and 4 laser pulses and/or the repetition rate of the individual laser pulses and/or laser bursts can be 100 kHz and/or the pulse or Burst energy can be between 10pJ and 5mJ.
  • the distance between the points of impact of the laser pulses can be estimated at 0.5pm to 50pm.
  • the laser beam 20 can have a focal zone 22, the diameter of which is smaller than 5 ⁇ m perpendicular to the direction of beam propagation.
  • the material removed by the laser beam 20 can be oriented precisely on the parting line 3 .
  • the different laser pulses can be superimposed or spatially overlap, so that there is an accumulation of heat in the material of the workpiece 1, as a result of which the material of the workpiece 1 is weakened.
  • the laser pulses it is also possible for the laser pulses to be separated so far from one another that the material of the workpiece 1 is perforated along the dividing line 3 only on the surface.
  • FIG. 1A also shows that the length of the focal zone 22 of the laser beam 20, which is elongated in the beam propagation direction, is greater than the material thickness D.
  • the focal zone 22 of the laser beam that is drawn in is 800 ⁇ m long, so that it is greater than 50 ⁇ m, but also smaller than 1.2 times the material thickness D. This ensures that the laser beam 20 in connection with the feed V notches both on the top and the bottom of the material of the workpiece 1 can generate. In particular, this ensures that the elongated focal zone 22 penetrates the top 10 and the bottom 12 .
  • FIG. 2 A possible separation step is shown in FIG. 2, which includes the application of a mechanical load to the material of the workpiece 1.
  • FIG. 2A shows that the indentations 4 were made by the non-diffracting laser beam 20 of FIG. 1A both on the upper side 10 and the lower side 12 .
  • a bending stress for example, can be applied as a mechanical force to the parts 100, 102 of the workpiece 1 to be separated. Bending stress can cause compression of the material of the workpiece 1 at the top 10 towards the indentation 4 while the material of the workpiece 1 at the bottom 12 is stretched away from the indentation. This creates a voltage gradient which is directed from the bottom 12 to the top 10 . As soon as the material stresses along the stress gradient are greater than the binding forces of the material of the workpiece 1, the material of the workpiece 1 relaxes, forming a crack which, for example, runs from the notch 4 in the upper side 12 to the notch 4 in the lower side 12 of the material of the workpiece 1 runs. This state of the material of the workpiece 1 is shown in FIG. 2B. FIG. 2C shows the subsequent state in which the parts 100, 102 of the workpiece are isolated and separated. The workpiece 1 was accordingly separated along the parting line 3 .
  • Such a separating step can in particular also be implemented by applying a thermal gradient, for example by irradiating the notches 4 with a CO2 continuous-wave laser.
  • a thermal gradient for example by irradiating the notches 4 with a CO2 continuous-wave laser.
  • the material stress exceeds the binding forces as a result of the targeted material weakening with type III modifications, so that the workpiece 1 self-separates. In any case, however, the weakening of the material along the separating line 3 determines the direction of the separating process.
  • FIG. 3A shows the method in which the focal zone 22 of the laser beam 20 is shorter than the material thickness D and a notch 4 is produced only in the upper side 10 of the material of the workpiece 1 .
  • the notch 4 in the upper side 10 of the workpiece is sufficient to bring about a targeted weakening of the material, so that the workpiece 1 can be separated along the separating line 3 in one separating step.
  • This is exemplary in the Figures 3B, C show where the parts 100, 102 of the workpiece 1 are separated by a separating step.
  • FIG. 4A shows a micrograph of the upper side 10 of a workpiece 1, which has been exposed to a non-diffracting laser beam 20.
  • FIG. 4B shows the associated height profile along the y-direction.
  • the indentation 4 is composed of a localized depth of material removal 40 and a surface removal of material 42 on the surface.
  • the surface removal of material 42 can be part of the surface modification discussed above.
  • the depth of the respective removal is calculated from the original surface 10 of the workpiece 1 .
  • a depth of material removal 40 of 2.5 pm results, while the removal of material surface 42 has a depth of removal of 1.5 pm.
  • the material surface removal 42 has a diameter or cross section of 80 ⁇ m, while the material depth removal measures only 20 ⁇ m in cross section.
  • the deep material removal 40 and the material surface removal 42 come about when the laser beam 20 hits the upper side 10 of the material of the workpiece 1 .
  • a material surface removal 42 is then first realized over the entire width of the laser beam 20 .
  • the material surface ablation 42 and the edges occurring at the edge of the ablation act as a shield--also due to the high refractive index of the material.
  • the formation of the non-diffracting laser beam is shifted to lower-lying material layers, so that it is only there that the elongated focal zone 22 and thus the material depth ablation 40 are formed.
  • the shape of the notch 4 can also reflect the intensity distribution of the laser beam 20 or the shape of the focal zone 22 . Since the formation of a notch 4 is based on non-linear absorption effects, as described above, the central laser beam part can, for example, form notches 4 particularly effectively, while partial laser beams close to the edge cannot do this.
  • FIGS. 4A, B it is shown in FIGS. 4A, B that the indentation on the upper side 10 of the material is continuous. Accordingly, in the present case, the feed rate or the repetition rate of the laser was so high that laser pulses introduced adjacent to each other overlap and thus produce a continuous predetermined breaking point on the upper side 10 of the workpiece 1 .
  • the notch 4 could accordingly also be produced in a single method step.
  • the perforation of a material of a workpiece 1 along a dividing line 3 is shown in FIG.
  • the laser pulses were introduced into the workpiece material at a distance of 50 pm.
  • the distance between the laser pulses can result in particular from the repetition frequency R of the laser and the feed rate V.
  • the superficial material removal takes the form of concentric diffraction rings, with the strength of the material removal increasing towards the center. In this area, the material surface removal 42 merges into the localized depth of material removal 40 .
  • FIG. 6 shows that the workpiece 1 can also comprise a layer system made from different materials 1A-1D.
  • the ablation threshold can also be reached in the transition area between the layers 1A-1D.
  • the removal threshold is the intensity threshold above which the material of the workpiece 1 is removed and can be increased or at least changed due to the chemical interface conditions.
  • each material layer can have a refractive index between 2.0 and 3.5.
  • FIG. 7A shows the transverse intensity distribution or the focal zone 22 of a non-diffracting laser beam 20.
  • the non-diffracting laser beam 20 is a so-called Bessel-Gaussian beam, the transverse intensity distribution in the x-y plane being radially symmetrical, so that the intensity of the non-diffracting laser beam 20 depends only on the radial distance from the optical axis. In particular, the diameter of the transverse intensity distribution is less than 5 pm.
  • FIG. 7B shows the longitudinal beam cross section, ie the longitudinal intensity distribution. The longitudinal intensity distribution shows an elongated region of high intensity, about 3mm in size. The longitudinal extent of the focal zone 22 is thus significantly greater than the transverse extent.
  • FIG. 8 shows an embodiment of the device 5 for carrying out the method.
  • the laser pulses are provided by the ultra-short pulse laser 50 and guided by beam-shaping optics 52 .
  • the laser beam 20 is directed onto the material 1 by the beam-shaping optics 52, for example by a telescope system 54 or another type of processing optics.
  • the beam shaping optics 52 are an axicon in order to shape the incident laser beam 20 into a non-diffracting laser beam 20 .
  • other elements can be substituted for the axicon to produce a non-diffractive laser beam.
  • Generates the axicon a conically tapering laser beam 20 from the preferably collimated input beam 20.
  • the beam-shaping optics 52 can also impose a non-radially symmetrical intensity distribution or focus zone 22 on the incident laser beam 20.
  • the laser beam 20 can finally be imaged in the material 1 via a telescope optics 54, which here consists of two lenses 540, 542, with the image being able to be an enlarging or a reducing image.
  • FIG. 9A shows a feed device 6 which is set up to move the processing optics 54 and the material 1 in a translatory manner along three spatial axes XYZ.
  • the laser beam 20 of the ultra-short pulse laser 50 is directed onto the material 1 by processing optics 54 .
  • the material 1 is arranged on a bearing surface of the feed device 6 , the bearing surface preferably neither reflecting nor absorbing the laser energy that the material does not absorb nor strongly scattering it back into the material 1 .
  • the laser beam 20 can be coupled into the processing optics 54 by a beam guidance device 56 .
  • the beam guiding device 56 can be a free-space path with a lens and mirror system, as shown in FIG. 9A.
  • the beam guidance device 56 can also be a hollow-core fiber with coupling-in and coupling-out optics, as shown in FIG. 9B.
  • the laser beam 20 is directed towards the material 1 by a mirror construction and introduced into the material 1 by the processing optics 54 .
  • the laser beam 20 causes a material removal in the material 1 .
  • the processing optics 54 can be moved and adjusted relative to the material with the feed device 6 so that, for example, a preferred direction or an axis of symmetry of the transverse intensity distribution of the laser beam 20 can be adapted to the feed trajectory and thus the dividing line 4 .
  • the feed device 6 can move the material 1 under the laser beam 20 with a feed rate V, so that the laser beam 20 notches the workpiece 1 along the desired parting line 3 .
  • the feed device 6 has a first axis system 60, with which the material 1 can be moved along the XYZ axes and, if necessary, rotated.
  • the feed device 6 can also have a workpiece holder 62 which is set up to hold the material 1 .
  • the feed device 6 can in particular also be connected to control electronics 64 , the control electronics 64 converting the user commands of a user of the device into control commands for the feed device 6 .
  • predefined cutting patterns can be stored in a memory of the control electronics 64 and the processes can be automatically controlled by the control electronics 64 .
  • the control electronics 64 can in particular also be connected to the ultra-short pulse laser 50 .
  • the control electronics 64 can request or trigger the output of a laser pulse or laser pulse train.
  • the control electronics 64 can also be connected to other components mentioned and thus coordinate the material processing.
  • a position-controlled pulse triggering can be implemented in this way, with an axis encoder 600 of the feed device 6 being read out, for example, and the axis encoder signal being able to be interpreted by the control electronics 64 as location information. It is thus possible for the control electronics 64 to automatically trigger the delivery of a laser pulse or laser pulse train if, for example, an internal adder unit that adds the distance covered reaches a value and resets itself to 0 after it has been reached. For example, a laser pulse or laser pulse train can be emitted automatically into the material 1 at regular intervals.
  • the laser pulses or laser pulse trains can be emitted automatically.
  • the control electronics 64 can also use the measured speed and the fundamental frequency made available by the laser 2 to calculate a distance or location at which a laser pulse train or laser pulse should be emitted. In this way it can be achieved in particular that the material modifications 5 in the material 1 do not overlap or that the laser energy is emitted uniformly along the dividing line 3 .

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Laser Beam Processing (AREA)

Abstract

La présente invention concerne un procédé de séparation d'une pièce (1), le matériau de la pièce (1) étant retiré le long d'une ligne de séparation (3) au moyen d'un faisceau laser (20) comprenant des impulsions laser ultracourtes d'un laser à impulsions ultracourtes (50), le matériau de la pièce (1) étant transparent à la longueur d'onde du faisceau laser (20) et présentant un indice de réfraction compris entre 2,0 et 3,5, de préférence entre 2,5 et 3,5, et la pièce (1) est séparée le long de l'indentation (4) qui se produit suite au retrait du matériau, lors d'une étape de séparation.
EP21836382.8A 2020-12-22 2021-12-07 Procédé de séparation d'une pièce Pending EP4267338A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102020134751.0A DE102020134751A1 (de) 2020-12-22 2020-12-22 Verfahren zum Trennen eines Werkstücks
PCT/EP2021/084593 WO2022135912A1 (fr) 2020-12-22 2021-12-07 Procédé de séparation d'une pièce

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EP4267338A1 true EP4267338A1 (fr) 2023-11-01

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EP21836382.8A Pending EP4267338A1 (fr) 2020-12-22 2021-12-07 Procédé de séparation d'une pièce

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US (1) US20230373034A1 (fr)
EP (1) EP4267338A1 (fr)
KR (1) KR20230117226A (fr)
CN (1) CN116723909A (fr)
DE (1) DE102020134751A1 (fr)
WO (1) WO2022135912A1 (fr)

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RU2013102422A (ru) 2010-07-12 2014-08-20 ФАЙЛЭЙСЕР ЮЭс-Эй ЭлЭлСи Способ обработки материалов с использованием филаментации
EP3169477B1 (fr) 2014-07-14 2020-01-29 Corning Incorporated Systèmes et procédés de traitement de matériaux transparents utilisant des lignes focales de faisceau laser réglable
JP2018523291A (ja) * 2015-06-01 2018-08-16 エバナ テクノロジーズ ユーエービー 半導体加工対象物のスクライブ方法
FR3054151B1 (fr) * 2016-07-25 2018-07-13 Amplitude Systemes Procede et appareil pour la decoupe de materiaux par multi-faisceaux laser femtoseconde
JP6981806B2 (ja) * 2017-08-09 2021-12-17 株式会社ディスコ 分割方法

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KR20230117226A (ko) 2023-08-07
DE102020134751A1 (de) 2022-06-23
WO2022135912A1 (fr) 2022-06-30
CN116723909A (zh) 2023-09-08
US20230373034A1 (en) 2023-11-23

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