Roundness-optimized through-holes in a workpiece

Abstract

The present invention relates to a method and a laser radiation source (2) for preparing an etching of at least one hole in a workpiece (1), in particular in the context of producing optimal through glass vias (TGV). The present invention is based on the general concept that both a principal maximum and a plurality of secondary maxima each lie above a relevant threshold fluence / intensity of a material of the workpiece (1) to be processed.

Description

[0001] Applicant: 03.03.2026 TRUMPF Laser- und Systemtechnik SE 2025P00098WO Roundness-optimized through holes in a workpiece

[0002]

[0001] The present invention relates to a method and a laser radiation source for preparing an etching of at least one hole in a workpiece, in particular in the context of the production of optimal Through Glass Vias (TGV).

[0003]

[0002] EP4049071A1 discloses a diffractive optical beam shaping element for imprinting a phase distribution onto a transverse beam profile of a laser beam with adjacent surface elements. Figures 30 and 3D of EP4049071A1 show a transverse intensity distribution and a section along the propagation direction after focusing the phase-imprinted beam. The transverse beam profile reveals the formation of a specially shaped main maximum and several secondary maxima. The secondary maxima lie, for example, below a relevant threshold fluence intensity of a material being processed.

[0004]

[0003] The present invention is based on the objective of enabling improved production of holes in the workpiece, in particular ensuring the optimization of the roundness of these holes. This assurance regarding the roundness of the holes increases the quality, especially in light of TGV, and minimizes the number of possible defective products, thus reducing manufacturing costs.

[0005]

[0004] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0006]

[0005] The present invention is based on the general idea that both a main maximum and several secondary maxima are located above a relevant threshold fluence intensity of a material to be processed in the workpiece.

[0007]

[0006] The inventive method for preparing at least one hole in a workpiece for etching comprises the following process steps: generating a pulsed laser beam, which has a transverse intensity distribution in the workpiece, by means of a laser radiation source, and generating a modification in the workpiece by means of this laser beam. According to the invention, the transverse intensity distribution has a circular region and a further region spaced apart from the circular region, wherein the modification within the workpiece is generated by the laser beam in both the circular region and the further region. This ensures an optimization of the roundness of the holes, in particular the through holes, which are formed during the etching process. Thus, roundness-optimized through holes are produced in the workpiece.The roundness of a hole in the workpiece can be defined as the difference between the largest and smallest diameters of the same hole, particularly in the same plane. This plane can be perpendicular and / or transverse to the propagation direction of the existing and / or used laser beam when considering roundness.

[0008]

[0007] The workpiece can be a glass disc or a disc that is largely transparent for the length of the laser wavelength used, in ceramic or crystalline form (for example, made of sapphire or silicon).

[0009]

[0008] The transverse intensity distribution relates to the intensity distribution of the laser beam in a plane perpendicular and / or transverse to the propagation direction of the laser beam.

[0010]

[0009] Between the circular area and the further area spaced apart from the circular area, it may be provided that no laser radiation is present and / or that laser radiation is present, but does not have sufficient intensity and / or fluence to form a modification in the workpiece. Such areas in which no modification occurs in the workpiece are subsequently referred to as intermediate sections. Modifications within the workpiece can be formed as defects (voids). Such defects can be accompanied by crack formation within the workpiece, whereby an etching solution can penetrate these cracks, thereby actively accelerating the etching process. Preferably, not only one crack is formed within the workpiece, but several, in particular at least two, three, four, five, six, seven, or eight cracks are formed within the workpiece.This ensures a higher etching rate and also an optimal shape of the TGV in the workpiece along the beam propagation direction of the laser beam.

[0011]

[0010] An annular intermediate section can be formed between the circular area and the further area spaced apart from the circular area.

[0012]

[0011] In an advantageous embodiment of the solution according to the invention, the circular region of the transverse intensity distribution has a circular center, and the further region of the transverse intensity distribution has n-fold rotational symmetry with respect to the circular center of the circular region, where n is at least two. In particular, n can be at least three, four, five, six, seven, or eight. This further optimizes the roundness of the holes formed during the etching process. The modification by the n-fold symmetry of the further region and / or by the symmetry of the circular region is particularly advantageous because it actively counteracts symmetry breaking due to misalignment of the laser radiation source, in particular the laser and / or the optics of the laser radiation source, thus preventing unfavorable crack formation due to asymmetric modes / cracks.According to the invention, the alignment of the modes / cracks is predetermined by the entire focus shape, i.e., the entire transverse intensity distribution, and is stronger than the alignment of the modes / cracks that can be caused by a misalignment of the laser radiation source and / or the beam quality.

[0013]

[0012] In an advantageous further development of the solution according to the invention, it is provided that the further region of the transverse intensity distribution is formed by several spaced-apart region sections. Intermediate sections can be formed between the spaced-apart region sections of the further region.

[0014]

[0013] In an advantageous embodiment of the solution according to the invention, the centroids of the spaced-apart region sections are arranged on an annulus, in particular a circle, around the center of the circular region. Alternatively or additionally, intensity maxima of the spaced-apart region sections can be arranged on an annulus, in particular a circle, around the center of the circular region. The annulus, in particular the circle, can have a center point that corresponds to the center of the circular region.

[0015]

[0014] In an advantageous embodiment of the solution according to the invention, the pulsed laser beam is generated by the laser radiation source in such a way that the pulsed laser beam is non-diffractive and / or diffraction-free, at least within the workpiece, and in particular completely within the workpiece. This optimizes the roundness along the entire hole. Regarding the definition and properties of non-diffractive 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. Reference is expressly and fully incorporated herein by reference.

[0016]

[0015] In an advantageous embodiment of the solution according to the invention, the laser radiation source is operated in single-pulse mode or pulse train mode, wherein the modification in the workpiece is generated by a single pulse in single-pulse mode or by a pulse train in pulse train mode. In other words, a single pulse can completely produce the modification in the workpiece, or several pulses of exactly one pulse train can completely produce the modification in the workpiece. The pulse train mode can also be called burst mode.

[0017]

[0016] In an advantageous embodiment of the solution according to the invention, the laser radiation source comprises at least one optical beam shaping element for generating the transverse intensity distribution. The optical beam shaping element can have phase values ​​and / or segments, wherein the segments have a phase offset that is not equal to TT. The optical beam shaping element can comprise an axicon and / or a modified axicon.

[0018]

[0017] In an advantageous further development of the solution according to the invention, it is provided that the workpiece is designed as an optically transparent workpiece, in particular as a glass workpiece and / or a glass sheet, and / or that the workpiece has a workpiece thickness of at least 20 pm.

[0019]

[0018] In an advantageous further development of the solution according to the invention, it is provided that the pulsed laser beam has a pulse duration of less than 200 ps and / or that the pulsed laser beam has a pulse energy of at least 10 pJ, and / or that the pulsed laser beam has a wavelength in the range of 300 nm to 10.6 pm, in particular 515 nm, and / or that the pulsed laser beam has a focusing with a numerical aperture of at least 0.05, in particular of at least 0.2.

[0020]

[0019] In an advantageous embodiment of the solution according to the invention, it is provided that the circular area has a radius greater than or equal to 100 nm and / or less than or equal to 4 pm, and / or that the further area has a radial section width greater than or equal to 100 nm and / or less than or equal to 4 pm, and / or that a radial distance of at least 2 pm is formed by an annular intermediate section between the circular area and the further area.

[0021]

[0020] In an advantageous further development of the solution according to the invention, it is provided that the circular area has a circular radius greater than or equal to 1 pm and / or less than or equal to 2 pm, and / or that the further area has a radial section width greater than or equal to 1 pm and / or less than or equal to 2 pm, and / or that a radial distance of at least 1 pm, in particular 2 pm, is formed by an annular intermediate section between the circular area and the further area.

[0021] In an advantageous further development of the solution according to the invention, it is provided that a positioning device is used to displace, in particular a transverse and / or longitudinal displacement, the workpiece after a modification of the workpiece has been produced, and / or that a positioning device is used to displace the workpiece in such a way that two immediately adjacent modifications in the workpiece have a distance greater than or equal to 10 pm and / or less than or equal to 2 mm.

[0022]

[0022] In an advantageous further development of the solution according to the invention, it is provided that a positioning device is used to displace, in particular a transverse and / or longitudinal displacement, the workpiece after a modification of the workpiece has been produced, and / or that a positioning device is used to displace the workpiece in such a way that two immediately adjacent modifications in the workpiece have a distance greater than or equal to 50 pm and / or less than or equal to 1 mm.

[0023]

[0023] Furthermore, the invention relates to a method for etching multiple holes in a workpiece comprising the following process steps: preparing the multiple holes of the workpiece for etching by means of the method described above, and etching the workpiece to enlarge the laser-induced modifications of the workpiece such that each laser-induced modification produces a hole, in particular a through hole, in the workpiece, wherein such a hole comprises exactly one opening in a first surface of the workpiece and exactly one opening in a second surface of the workpiece, wherein a plurality of holes have a roundness of less than 5 pm, in particular less than 4 pm, on the first surface and / or the second surface of the workpiece.

[0024]

[0024] Furthermore, the invention relates to a workpiece which was manufactured using the method according to one of the preceding claims.

[0025]

[0025] Furthermore, the invention relates to a laser radiation source which is designed and configured to be used in the method described above.

[0026]

[0026] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures with reference to the drawings.

[0027]

[0027] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without leaving the scope of the present invention.

[0028]

[0028] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, where the same reference numerals refer to identical or similar or functionally identical components.

[0029]

[0029] They show, schematically,

[0030] Fig. 1 shows a laser radiation source during the processing of a workpiece, Fig. 2 shows the workpiece after processing using the laser radiation.

[0031] Fig. 3 shows an intensity distribution of the laser radiation from the laser radiation source.

[0032] Fig. 4 shows another intensity distribution of the laser radiation.

[0033]

[0030] Fig. 1 shows a laser radiation source 2 which is designed and set up to generate a pulsed laser beam 3 with which a workpiece 1 is prepared for etching.

[0034]

[0031] Fig. 2 shows the workpiece 1 after preparation for etching. Here, a displacement, in particular a transverse and / or longitudinal displacement, of the workpiece 1 was carried out by means of a positioning device (not shown) after a first modification 20 of the workpiece 1 in order to form a further modification 21 of the workpiece 1 at a distance 22.

[0035]

[0032] The transverse intensity distribution 4 of the laser beam 3 with which these modifications 20 and 21 were each generated is explained by way of example with reference to Fig. 3 and Fig. 4.

[0036]

[0033] The method for preparing the etching of at least one hole in the workpiece 1 comprises the following process step: generating the pulsed laser beam 3 by means of the laser radiation source 2, wherein the laser beam 3 has a transverse intensity distribution 4 in the workpiece 1. Furthermore, the method comprises the additional process step: generating the modifications 20 and 21 in the workpiece 1 by means of the laser beam 3. According to the invention, the transverse intensity distribution 4 of the laser beam 3 has a circular region 5 and a further region 6 spaced apart from the circular region 5, wherein the respective modification 20 or 21 was generated within the workpiece 1 by the laser beam 3 both in the circular region 5 and in the further region 6.

[0034] Between the circular region 5 and the further region 6 spaced apart from the circular region, it may be provided that no laser radiation is present and / or that laser radiation is present, but does not have sufficient intensity and / or fluence to form a modification 20 / 21 in the workpiece 1. Such regions in which no modification takes place in the workpiece 1 are called intermediate sections 12, 13, 14, 15, 16.

[0037]

[0035] The circular region 5 of the transverse intensity distribution has a circular center 7, wherein the further region 6 of the transverse intensity distribution has n-fold rotational symmetry with respect to the circular center 7 of the circular region 5, where n is at least two.

[0038]

[0036] The further region 6 of the transverse intensity distribution is formed in Fig. 4 by several spaced-apart region sections 8, 9, 10, 11.

[0039]

[0037] The circular region 5 can have a radius 17 greater than or equal to 1 pm and / or less than or equal to 2 pm. The further region 6 can have a radial section width 18 greater than or equal to 1 pm and / or less than or equal to 2 pm. The annular intermediate section 16 between the circular region 5 and the further region 6 can have a radial distance 19 of at least 1 pm.

[0040]

[0038] The laser radiation source 2 can be operated in single-pulse mode or pulse train mode, wherein the respective modification 20 or 21 in the workpiece 1 is generated by exactly one single pulse in single-pulse mode or exactly one pulse train in pulse train mode. The laser radiation source 2 can have a beam shaping element (not shown) for generating the transverse intensity distribution 4 shown.

[0041]

[0039] Subsequently, the workpiece 1 is etched (not shown) to enlarge the laser-induced modifications 20 and 21 of the workpiece 1 such that each laser-induced modification 20, 21 creates a hole, in particular a through hole, in the workpiece 1, wherein such a hole comprises exactly one opening in a first surface of the workpiece 1 and exactly one opening in a second surface of the workpiece 1, wherein a plurality of holes have a roundness of less than 5 pm, in particular less than 4 pm, on the first surface and / or the second surface of the workpiece 1. Reference numeral list

[0042] 1 workpiece

[0043] 2 Laser radiation source

[0044] 3 Laser beam

[0045] 4 Intensity distribution

[0046] 5 circular area

[0047] 6 more areas

[0048] 7 Circle center

[0049] Section 8

[0050] 9 area sections

[0051] 10 area sections

[0052] 11 area sections

[0053] 12 Intermediate section

[0054] 13 Intermediate section

[0055] 14 Intermediate section

[0056] 15 Intermediate section

[0057] 16 circular intermediate section 17 circle radius

[0058] 18 radial section width

[0059] 19 radial spacing

[0060] 20 first modification

[0061] 21 further modifications

[0062] 22 Distance between the modifications

Claims

Patent claims 1. Method for preparing an etching of at least one hole in a workpiece (1), comprising the following process steps: - By means of a laser radiation source (2), generating a pulsed laser beam (3) which has a transverse intensity distribution (4) in the workpiece (1), - By means of the laser beam (3), generating a modification (20, 21) in the workpiece (1), characterized in that, - that the transverse intensity distribution (4) comprises a circular area (5) and a further area (6) spaced apart from the circular area (5), wherein the modification (20, 21) within the workpiece (1) is generated by the laser beam (3) both in the circular area (5) and in the further area (6).

2. Method according to claim 1, characterized by - that the circular area (5) of the transverse intensity distribution has a circular center (7), - wherein the further region (6) of the transverse intensity distribution has n-fold rotational symmetry with respect to the center of the circle (7) of the circular region (5), where n is at least two.

3. Method according to claim 2, characterized by that n is at least three or four or five or six or seven or eight.

4. Method according to any one of the preceding claims, characterized by that the further area (6) of the transverse intensity distribution is formed by several spaced-apart area sections (8, 9, 10, 11).

5. Method according to claim 4, characterized by - that the centroids of the spaced-apart area sections (8, 9, 10, 11) are arranged on an annulus around the center of the circular area, and / or - that the intensity maxima of the spaced-apart area sections (8, 9, 10, 11) are arranged on an annulus around the center of the circular area.

6. Method according to any one of the preceding claims, characterized by that the pulsed laser beam (3) is generated by means of the laser radiation source (2) in such a way that the pulsed laser beam (3) is non-diffractive and / or diffraction-free at least within the workpiece (1), in particular completely within the workpiece (1).

7. Method according to any of the preceding claims, characterized by that the laser radiation source (2) is operated in single-pulse mode or pulse train mode, wherein the modification (20, 21) in the workpiece (1) is generated by a single pulse in single-pulse mode or a pulse train in pulse train mode.

8. Method according to any one of the preceding claims, characterized by that the laser radiation source (2) has at least one optical beam shaping element for generating the transverse intensity distribution (4).

9. Method according to any one of the preceding claims, characterized by - that the workpiece (1) is designed as an optically transparent workpiece, in particular as a glass workpiece and / or a glass pane, and / or - that the workpiece (1) has a workpiece thickness of at least 20 pm.

10. Method according to any one of the preceding claims, characterized by - that the pulsed laser beam (3) has a pulse duration of less than 200 ps and / or that the pulsed laser beam (3) has a pulse energy of at least 10 pJ, and / or - that the pulsed laser beam (3) has a wavelength in the range of 300 nm to 10.6 pm, in particular 515 nm, and / or - that the pulsed laser beam (3) has a focus with a numerical aperture of at least 0.05, in particular of at least 0.2.

11. Method according to any one of the preceding claims, characterized by - that the circular area (5) has a circular radius (17) greater than or equal to 100 nm and / or less than or equal to 4 pm, and / or - that the further area (6) has a radial section width (18) greater than or equal to 100 nm and / or less than or equal to 4 pm, and / or - that a radial distance (19) of at least 2 pm is formed by an annular intermediate section (16) between the circular area (5) and the further area (6).

12. Method according to any one of the preceding claims, characterized by - that a positioning device is used to displace, in particular a transverse and / or longitudinal displacement, the workpiece (1) after a modification (20, 21) of the workpiece (1) has been produced, and / or - that by means of a positioning device a displacement of the workpiece (1) is carried out such that two immediately adjacent modifications (20, 21) in the workpiece (1) have a distance (22) greater than or equal to 10 pm and / or less than or equal to 2 mm.

13. Method for etching multiple holes in a workpiece (1) comprising the following process steps: - Preparation for etching the multiple holes of the workpiece (1) by means of the method according to one of the preceding claims, and - Etching of the workpiece (1) to enlarge the laser-induced modifications (20, 21) of the workpiece (1) such that each laser-induced modification (20, 21) produces a hole, in particular a through hole, in the workpiece (1), wherein such a hole comprises exactly one opening in a first surface of the workpiece (1) and exactly one opening in a second surface of the workpiece (1), and / or wherein a plurality of holes has a roundness of less than 5 pm, in particular less than 4 pm, on the first surface and / or the second surface of the workpiece (1).

14. Workpiece (1) which has been modified and / or manufactured using the method according to any one of the preceding claims.

15. Laser radiation source (2) which is designed and configured to be used and / or employed in the method according to any one of claims 1 to 13.

Images