Method for forming high-speed precision through holes using an infrared laser

Abstract

The present invention discloses a method for forming high-speed precision through holes using an infrared laser, which sequentially irradiates a workpiece by a scanning method using a mirror structure in which at least one or more driving units are combined with one modulated Bessel beam, and performs fine processing on the workpiece at high speed and precision in various sizes or patterns to change the shape of the workpiece. After forming a laser scanning processing pattern, wet etching is performed to significantly reduce the laser processing time compared to the prior art, enabling the workpiece to be laser processed at high speed, and improving productivity by shortening the etching time.

Description

Technical Field

[0001] The present invention relates to a method for forming high-speed and precise through-holes using an infrared laser. More specifically, a modulated single Bessel beam is sequentially irradiated onto a workpiece in a scanning manner using a mirror structure coupled with at least one driving unit, and then finely processed at high speed and precision into various sizes or patterns to change the properties of the workpiece. After forming a laser scanning processing pattern, wet etching is performed to significantly shorten the laser processing time compared to the prior art, enabling the workpiece to be laser processed at high speed, and improving productivity by shortening the etching time. The present invention relates to a method for forming high-speed and precise through-holes using an infrared laser.

Background Art

[0002] Lasers are widely used in processing such as cutting a workpiece (object to be processed) or forming a through-hole. These laser processes involve shaping a laser beam into a desired shape using optical elements such as lenses and irradiating the shaped laser beam onto the workpiece so as to be suitable for the processing operation.

[0003] In particular, in processing operations such as cutting a brittle material that is difficult to process, such as a transparent glass substrate, or forming a through-hole, the laser beam can be used efficiently. However, when processing a glass substrate, cracks may occur in the workpiece due to the laser, and the cracks can propagate.

[0004] Furthermore, when a change in properties is generated inside due to seepage or foreign matter outside the brittle material glass substrate, a problem may occur where the inner wall of the through-hole becomes non-uniform.

[0005] Also, when forming a fine through-hole in a glass substrate using a laser, it is difficult to perform precise processing, the working time is too long, and there is a problem of reducing productivity.

[0006] Among the related prior art documents, there is Korean Patent Publication No. 10-2016-0063264 (published on June 3, 2016).

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to sequentially irradiate a workpiece with a modulated single Bessel beam in a scanning manner using a mirror structure to which at least one or more driving units are coupled, and to perform high-speed and precise microfabrication on various sizes or patterns to change the properties of the workpiece. After forming a laser scanning processing pattern, by performing wet etching, not only can the laser processing time be significantly reduced compared to the prior art, enabling the workpiece to be laser processed at high speed, but also the productivity can be improved by shortening the etching time. The present invention provides a method for forming a high-speed and precise through-hole using an infrared laser.

Means for Solving the Problems

[0008] A method for forming a high-speed and precise through-hole using an infrared laser according to an embodiment of the present invention to achieve the above object includes: (a) aligning an infrared laser device above a workpiece; (b) modulating a laser beam emitted from the infrared laser device into a Bessel beam; (c) performing a laser processing operation of sequentially irradiating the modulated Bessel beam onto the formation regions of the through-holes of the workpiece in a scanning manner respectively to form a laser scanning processing pattern for locally changing the properties of the workpiece; and (d) etching the workpiece on which the laser scanning processing pattern is formed to form through-holes for each formation region of the through-holes.

[0009] The laser beam uses an ultrashort laser having a wavelength of 900 to 1,200 nm and a pulse width of 50 femtoseconds to 50 picoseconds.

[0010] The laser scan processing pattern is formed to have an array structure in which single dots formed by the laser processing are separated at regular or irregular intervals in a plan view so as to have a shape corresponding to the through hole.

[0011] The laser scan processing pattern has an array structure in which single dots formed by the laser processing are separated at regular or irregular intervals of 20 μm or less in a plan view, and has at least one shape selected from among polygons including triangles, squares, pentagons, hexagons, octagons, and star shapes, circles, and ellipses, which are shapes corresponding to the through hole.

[0012] The laser scan processing pattern has, in a plan view, a first laser scan processing pattern arranged to be separated at regular or irregular intervals so as to have a shape corresponding to the through hole, and at least one second laser scan processing pattern arranged inside the first laser scan processing pattern.

[0013] The second laser scan processing pattern has an array structure having the same or a different shape from that of the first laser scan processing pattern.

[0014] The laser scan processing pattern is formed to have an array structure of a straight line or a curve in which a plurality of dots are connected to each other so as to have a shape corresponding to the through hole in a plan view.

[0015] The workpiece is preferably a flat glass substrate.

[0016] In the step (c), the scanning laser processing is performed by using a mirror structure coupled with at least one driving unit, and the scanning laser processing is performed with a stabilization time of 10 ms or less.

[0017] In the step (d), each of the through holes located in the formation regions of the through holes is formed in the same plane or at least partially formed in different planes from each other.

[0018] In the step (d), wet etching using an etchant containing at least one selected from a fluorinated etchant and a non-fluorinated etchant is used for the etching.

[0019] The step (d) includes: (d-1) a step of infiltrating an etchant into the laser scan processing pattern of the workpiece locally transformed by the laser processing treatment, removing a part of the exposed surface of the workpiece along the thickness direction, and forming a plurality of etching grooves; and (d-2) a step of forming through holes by naturally dropping or corroding the transformed dummy portion of the workpiece located in the space between the laser scan processing patterns while the etchant penetrates along the plurality of etching grooves in the direction of the center of the thickness of the workpiece.

[0020] The inner wall of the through hole has a taper angle from an acute angle to an obtuse angle with respect to the horizontal plane of the workpiece.

Advantages of the Invention

[0021] The method for forming a high-speed and precision through hole using an infrared laser according to the present invention irradiates a workpiece sequentially in a scanning manner by scanning a modulated single Bessel beam using a mirror structure to which at least one driving unit is coupled, and performs fine processing at high speed and precision in various sizes or patterns.

[0022] Thus, in the method for forming a high-speed and precision through hole using an infrared laser according to the present invention, since a scanning method of laser processing while adjusting the reflection angle of a mirror structure to which at least one driving unit is coupled is applied, unlike a general method for forming a through hole that only moves a stage, not only can the stabilization time be shortened to approximately 10 ms or less during laser processing, but also the size of the workpiece to be laser processed is not affected.

[0023] Therefore, the method for forming a high-speed precision through-hole using an infrared laser according to the present invention can perform laser processing at a speed 100 times or more higher than that of a general method for forming a through-hole, so that the productivity can be remarkably improved.

[0024] Furthermore, the method for forming a high-speed precision through-hole using an infrared laser according to the present invention can control the processing position of the workpiece at high speed and precisely, and wet etching can be performed in a state where the internal properties of the workpiece are locally changed so as to have the same or similar size or shape as the through-hole. Therefore, the etching time can be significantly reduced, the etchant consumption cost can be reduced, and the quality uniformity of a plurality of through-holes formed over the entire workpiece can be improved together with the productivity. As a result, in the present invention, since the dummy portion with changed properties of the workpiece located between the plurality of etching grooves is removed while naturally falling off or corroding, a through-hole with a desired size can be formed in a very short time as compared with a general method for forming a through-hole.

[0025] Furthermore, in the method for forming a high-speed precision through-hole using an infrared laser according to the present invention, one vessel beam is sequentially irradiated in a scanning manner for each formation region of the through-hole of the workpiece to form a laser scanning processing pattern, and then wet etching is performed. Therefore, in the present invention, even if some of the laser scanning processing patterns located for each formation region of the through-hole are defective due to seepage, foreign matters, etc. outside the workpiece and the change in the properties of the workpiece is partially uniform, since other laser scanning processing patterns are arranged around, it may be possible to ensure the quality of the through-hole product without significant influence during wet etching.

[0026] As a result, the method for forming a high-speed precision through-hole using an infrared laser according to the present invention can ensure uniform size between the diameter of the surface portion of the through-hole and the diameter of the central portion of the through-hole during wet etching.

[0027] In addition, in the method for forming a high-speed precision through-hole using an infrared laser according to the present invention, wet etching is performed using a laser scan processing pattern having an array structure separated at regular or irregular intervals, so that through-holes having substantially the same or similar shapes as the laser scan processing pattern can also be varied in various shapes.

Brief Description of the Drawings

[0028]

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Mode for Carrying Out the Invention

[0029] The advantages, features, and the method for achieving them of the present invention will become clear by referring to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. However, this embodiment is provided to make the disclosure of the present invention complete and to fully inform those with ordinary knowledge in the technical field to which the present invention pertains of the scope of the invention, and the present invention is only defined by the scope of the claims. The same reference numerals throughout the specification refer to the same components.

[0030] Hereinafter, with reference to the accompanying drawings, a method for forming a high-speed precision through-hole using an infrared laser according to a preferred embodiment of the present invention will be described in detail as follows.

[0031] FIGS. 1 to 4 are process cross-sectional views showing a method for forming a through-hole using a normal ultrashort infrared laser. Further, FIG. 5 is a schematic diagram for explaining an optical modulation device for a normal laser vessel beam, and FIG. 6 is a plan view showing laser processing dots formed using the optical modulation device for a laser vessel beam of FIG. 5.

[0032] As shown in FIGS. 1, 5, and 6, after aligning an optical modulation device for a normal laser vessel beam above the workpiece 110, the vessel beam (BB) emitted from the optical modulation device for the laser vessel beam is irradiated onto the workpiece 110 to form a laser processing dot 125.

[0033] Here, the laser beam (LB) emitted from the optical modulation device for the normal laser vessel beam is modulated into a vessel beam (BB) while passing through the objective lens-based optical element 140, and the modulated vessel beam (BB) is irradiated onto the workpiece 110 to form a laser processing dot 125. The optical element 140 may be a non-diffracting element for modulating the laser beam (LB) into the vessel beam (BB), but is not limited thereto. Therefore, the laser beam (LB) may be modulated into an annular vessel beam (BB) when viewed from the traveling direction of the beam while passing through the objective lens-based optical element 140.

[0034] Next, as shown in FIGS. 2 to 4, the workpiece 110 on which the laser processing dot 125 is formed is etched to form a through hole (TH).

[0035] In this step, although wet etching using a fluorinated etchant, a non-fluorinated etchant, etc. is used for the etching, this is exemplary, and any etchant that can etch a glass substrate can be used without limitation.

[0036] At this time, FIG. 2 shows the initial process of the etching. It can be confirmed that the etching is gradually performed while the etchant penetrates into the portion transformed by the laser processing dot 125, and an etching groove (E) having a first width (W1) is formed.

[0037] FIG. 3 shows the middle process of etching. As time passes, it can be confirmed that the size expands to an etching groove (E) having a second width (W2) wider than the first width (W1) while the etchant further penetrates along the etching groove (E).

[0038] Furthermore, FIG. 4 shows the final process of etching. As time passes, in the reaction with the etchant, the diameter of the etching groove expands while the workpiece 110 is gradually removed along the etching groove (E in FIG. 3), and finally, the upper and lower etching grooves are connected to form a through hole (TH).

[0039] The above-described general method for forming a through hole is transparent. In order to form a micrometer-sized fine through hole (TH) in the transparent and brittle workpiece 110, a Bessel beam (BB) modulated using an infrared laser is generally irradiated onto the workpiece 110 to form laser processing dots 125 for each formation region of the through hole. After the transformation, the wet etching time is adjusted to form the desired final size.

[0040] However, the general method for forming a through hole is a step-and-repeat processing method in which the Bessel beam (BB) is irradiated for each formation region of the through hole while moving the stage on which the workpiece 110 is mounted. When the stage is moved to the formation region of the through hole, the time including the acceleration / deceleration time and the stabilization time usually takes as long as 100 ms to 1,000 ms. Therefore, as the size of the workpiece 110 increases for laser processing, the size of the stage has to increase, and the acceleration / deceleration and stabilization times further increase. As a result, when the size of the workpiece 110 increases, the overall laser processing time increases significantly, reducing productivity. Also, as the number of through holes (TH) increases, the acceleration / deceleration and stabilization times also increase accordingly, thereby significantly increasing the processing time and reducing productivity.

[0041] In addition, in a general method for forming through-holes, since the Bessel beam (BB) is irradiated for each formation region of the through-holes in the workpiece 110, the Bessel beam (BB) irradiated along the thickness direction of the workpiece 110 focuses on only one processing position for laser processing. Therefore, if there are surface defects such as foreign matter or stains on the workpiece 110 at the processing position, there is a high risk that a transformation cannot be uniformly generated inside the brittle workpiece 110. Ultimately, this causes defects in the through-holes (TH) during wet etching, not only inhibiting the uniformity of the sizes or shapes of the plurality of through-holes (TH) located in each formation region of the through-holes, but also causing non-uniformity in the size between the diameter (d1) of the surface portion of the through-hole (TH) and the diameter (d2) of the central portion of the through-hole (TH) during wet etching, acting as a factor to reduce the taper angle (θ) and degrading the product quality.

[0042] Therefore, in a general method for forming through-holes, the quality of the plurality of final through-holes (TH) formed for each formation region of the through-holes in the workpiece 110 is inevitably greatly affected by the performance of the etching process, and there are limitations in ensuring the quality of uniform through-holes (TH). Depending on the final size of the through-holes (TH), the etching time takes more than several hours, and there are limitations in mass productivity.

[0043] In addition, a general method for forming through-holes is sensitively affected by the surface state such as whether foreign matter or stains on the surface of the workpiece 110 can be removed, and there are limitations in ensuring the quality uniformity of the through-holes (TH) distributed throughout the workpiece 110.

[0044] In addition, in a general method for forming through-holes, the Bessel beam (BB) is irradiated for each formation region of the through-holes in the workpiece 110 to form one laser processing dot 125, and the through-hole (TH) is formed by gradually expanding the hole size of one laser processing dot 125 by wet etching using an etchant. Therefore, there are limitations in varying the shape of the through-hole (TH).

[0045] To solve this problem, the method for forming a high-speed and precision through-hole using an infrared laser according to an embodiment of the present invention irradiates a workpiece sequentially in a scanning manner using a mirror structure to which at least one or more driving units are coupled to scan a modulated single Bessel beam, and performs fine processing at high speed and precision into various sizes or patterns.

[0046] Thus, in the method for forming a high-speed and precision through-hole using an infrared laser according to an embodiment of the present invention, since a scanning method of laser processing while moving a mirror structure to which at least one or more driving units are coupled is applied, unlike a general method for forming a through-hole that only moves a stage, during laser processing, not only can the stabilization time be shortened to approximately 10 ms or less, more preferably 1 ms or less, but also, thereby, the size of the workpiece to be laser processed is not affected.

[0047] Therefore, the method for forming a high-speed and precision through-hole using an infrared laser according to an embodiment of the present invention can perform laser processing at a speed 100 times or more higher than a general method for forming a through-hole, and thus, the productivity can be significantly improved.

[0048] Furthermore, the method for forming a high-speed and precision through-hole using an infrared laser according to an embodiment of the present invention can control the processing position of the workpiece at high speed and precision, and wet etching can be performed in a state where the internal properties of the workpiece are locally changed so as to have the same or similar size or shape as the through-hole, so that the etching time can be significantly reduced, the etchant consumption cost is reduced, and together with the productivity, the quality uniformity of a plurality of through-holes formed throughout the workpiece can be improved.

[0049] Hereinafter, with reference to the accompanying drawings, the method for forming a high-speed and precision through-hole using an infrared laser according to an embodiment of the present invention will be described in detail.

[0050] FIG. 7 is a process flow diagram showing a method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention, FIG. 8 is a schematic diagram showing an infrared laser device according to an embodiment of the present invention, and FIG. 9 is a plan view showing a laser scan processing pattern formed using the infrared laser device of FIG. 8. FIGS. 10 to 12 are cross-sectional process diagrams showing a method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention.

[0051] As shown in FIG. 7, the method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention includes an alignment step (S210) of an infrared laser device, a modulation step (S220) of a laser beam, a formation step (S230) of a laser scan processing pattern, and a formation step (S240) of a through-hole by wet etching.

[0052] Alignment of Infrared Laser Device As shown in FIGS. 7 and 8, in the alignment step (S210) of the infrared laser device, the infrared laser device 200 is aligned above the workpiece 210.

[0053] Here, the workpiece 210 may have a flat plate shape, but is not limited thereto. Further, the workpiece 210 may be a transparent glass substrate made of a brittle material that is difficult to process. However, the workpiece 210 is not limited to a transparent glass substrate, and may include various materials such as an opaque substrate, a metal material, and a semiconductor wafer.

[0054] Modulation of Laser Beam As shown in FIGS. 7 and 8, in the modulation step (S220) of the laser beam, the laser beam (LB) emitted from the infrared laser device 200 is modulated into a Bessel beam (BB).

[0055] Here, the infrared laser device 200 may include a laser unit 220, a first optical unit 240, and a second optical unit 260.

[0056] The laser unit 220 emits a laser beam (LB) to process the workpiece 210. These laser units 220 can generate laser light with pulses and emit it in the form of a beam. At this time, the emitted laser beam (LB) may have ultrashort pulses or burst pulses that are pulses having a wavelength, energy, and duration suitable for processing the workpiece 210. More specifically, for the laser beam (LB), an ultrashort laser having a wavelength of 900 to 1,200 nm and a pulse width of 50 femtoseconds to 50 picoseconds can be used. Also, the laser beam (LB) may have a circular or Gaussian beam shape when viewed from the traveling direction.

[0057] The first optical unit 240 is disposed in the traveling path of the laser beam (LB) and modulates the incident laser beam (LB) into a Bessel beam (BB). For this purpose, the first optical unit 240 may include a first optical element 242 for modulating the laser beam (LB) into a Bessel beam (BB) and a second optical element 244 disposed behind the first optical element 242.

[0058] The first optical element 242 may be a non-diffracting element for modulating the laser beam (LB) into a Bessel beam (BB), but is not limited thereto. These first optical elements 242 may be diffracting elements for modulating the laser beam (LB) into a beam capable of creating filamentation by non-linear absorption.

[0059] In one example, the first optical element 242 may be a conical prism or an axicon lens for modulating the laser beam (LB) into a Bessel beam (BB). Thus, while passing through the first optical element 242, the laser beam (LB) can be modulated into an annular Bessel beam (BB) when viewed from the traveling direction of the beam.

[0060] These first optical elements 242 are not limited to conical prisms or axicon lenses, and various optical elements capable of modulating a laser beam (LB) into a Bessel beam (BB) can be used. For example, the first optical element 242 can also use various optical elements such as diffractive optical elements like diffractive optical elements and spatial light modulators.

[0061] Furthermore, after the laser beam (LB) passes through the first optical element 242 and is modulated into a Bessel beam (BB), a second optical element 244 that can limit the expansion of the irradiation area of the Bessel beam may be attached behind the first optical element 242 so as to be suitable for processing the workpiece 210.

[0062] That is, the second optical element 244 may be an optical element for causing the Bessel beam (BB) modulated by the first optical element 242 to travel parallel to the optical axis. In one example, the second optical element 244 may be a collimating lens or a collimating lens. After the optical axes of the Bessel beams (BB) that have passed through the second optical element 244 are arranged in parallel, they can enter the second optical unit 260.

[0063] The first optical element 242 and the second optical element 244 pass through the second optical element 244 and enter the second optical unit 260 by appropriately selecting or adjusting their respective optical properties, arrangement intervals, and the like.

[0064] Here, the second optical unit 260 is for reflecting the Bessel beam (BB) modulated by the first optical unit 240 onto the workpiece 210, and may include a mirror structure 262 and a focusing lens 264.

[0065] The mirror structure 262 is coupled to at least one drive unit. As a result, the reflection angle of the mirror structure 262 can be adjusted in real time by at least one drive unit, enabling the high-speed reflection of the Bessel beam (BB) in the direction of the workpiece 210. These mirror structures 262 may be a Fine Steering Mirror (FSM) coupled with one drive unit or a scanner coupled with two or more drive units.

[0066] The mirror structure 262 can move the path of the Bessel beam (BB) modulated by the first optical unit 240. That is, the mirror structure 262 can continuously change the optical axis direction of the Bessel beam (BB) modulated by the first optical unit 240 within a predetermined angle range, thereby enabling the Bessel beam (BB) modulated by the first optical unit 240 to be sequentially irradiated in a scanning manner for each formation region of the through hole on the workpiece 210.

[0067] The mirror structure 262 may include at least one or more mirrors whose angles are adjustable. As a result, the Bessel beam (BB) incident on the mirror structure 262 is reflected by the mirror, and the reflected Bessel beam (BB) may have its reflection angle adjusted. For example, the mirror structure 262 may include a plurality of mirrors that are each rotatable along a rotation axis arranged in at least two axial directions, and may be composed of Galvano Mirrors. These mirror structures 262 are not limited to Galvano Mirrors.

[0068] The Bessel beam (BB) whose path has been changed by the mirror structure 262 can be focused on the workpiece 210 by the focusing lens 264.

[0069] The focusing lens 264 may be disposed behind the scanner 262 and above the workpiece 210. Thereby, the Bessel beam (BB) emitted from the mirror structure 262 can be irradiated in a scanning manner by the focusing lens 264 for each formation region of the through hole of the workpiece 210.

[0070] Formation of Laser Scanning Processing Pattern As shown in FIGS. 7 to 10, in the formation stage (S230) of the laser scanning processing pattern, a laser processing process is performed in which the modulated Bessel beam (BB) is sequentially irradiated in a scanning manner for each formation region of the through hole of the workpiece 210, and a laser scanning processing pattern 225 for locally changing the properties of the workpiece 210 is formed.

[0071] These laser scanning processing patterns 225 are respectively arranged for each formation region of the through hole.

[0072] At this time, in the present invention, laser processing is performed by sequentially irradiating the workpiece 210 in a scanning manner using a mirror structure 262 to which at least one or more drive units are coupled with one modulated Bessel beam (BB).

[0073] Therefore, in the present invention, since one modulated Bessel beam (BB) is irradiated in a scanning manner while adjusting the reflection angle of the mirror structure 262 to which at least one or more drive units are coupled, it is possible to form the laser scanning processing pattern 225 at high speed and with high precision.

[0074] Thus, in the present invention, a scanning method of laser processing while adjusting the reflection angle of the mirror structure 262 to which at least one or more drive units are coupled is applied. This means that when moving to the formation region position of the through hole (TH), the acceleration / deceleration and stabilization time is 10 ms or less, which is much shorter than the time for moving only the stage to the formation region position of the through hole. As a result, the size of the workpiece 210 to be laser processed is not affected.

[0075] Therefore, the method for forming a high-speed and precision through-hole using an infrared laser according to an embodiment of the present invention can perform laser processing at a speed 100 times or more higher than that of a general method for forming a through-hole, so that the productivity can be remarkably improved.

[0076] Here, although the laser scan processing pattern 225 is preferably formed to have an array structure in which single dots formed by laser processing are separated at regular intervals of 20 μm or less so that the shape of the single dot corresponds to that of the through-hole in a plan view, it is not limited thereto. That is, the laser scan processing pattern 225 may be formed to have an array structure in which single dots formed by laser processing are separated at irregular intervals of 20 μm or less so that the shape of the single dot corresponds to that of the through-hole in a plan view.

[0077] Here, as shown in FIG. 9, the laser scan processing pattern 225 may be formed such that the modulated Bessel beam is irradiated in a scanning manner for each formation region of the through-hole of the workpiece 210 using a mirror structure to which at least one or more driving parts are coupled, and a plurality of laser processing dots separated at regular intervals have a circular array structure.

[0078] In this way, when the laser scan processing pattern 225 is formed to be separated at regular or irregular intervals so as to have a circular array structure, the area in which the workpiece 210 is changed in properties by the Bessel beam (BB) irradiated to the workpiece 210 for each formation region of the through-hole can be increased.

[0079] Therefore, the area in which the properties of the workpiece 210 are changed increases in proportion to the number of dots of the laser scan processing pattern 225. This ultimately increases the number of dots of the laser scan processing pattern 225 that generates fine holes in the workpiece 210 by laser processing during wet etching, so that the area where the etchant can easily penetrate increases, and the etching time can be significantly reduced.

[0080] On the other hand, FIG. 13 is a plan view showing various application examples of the laser scan processing pattern according to an embodiment of the present invention.

[0081] As shown in FIG. 13, the laser scan processing pattern 225 irradiates a workpiece with a modulated Bessel beam in a scanning manner and arranges it at regular or irregular intervals, so that after wet etching, it has the same or a similar form as the shape of the through holes finally formed.

[0082] Therefore, since the shape of the through holes is determined by the arrangement shape of the laser scan processing pattern 225, various changes in the arrangement shape of the laser scan processing pattern 225 are possible, and various formations of the through holes can be made in corresponding shapes.

[0083] That is, as shown in FIG. 13(a), the laser scan processing pattern 225 may have a circular arrangement structure of a plurality of laser processing dots in a plan view.

[0084] Also, as shown in FIGS. 13(b), (c), and (d), the laser scan processing pattern 225 may have a star-shaped, square-shaped, and triangular arrangement structure of a plurality of laser processing dots in a plan view, respectively.

[0085] However, the laser scan processing pattern 225 is not limited to the arrangement structure of the above-described shapes. That is, the laser scan processing pattern 225 can be applied in various ways, such as an arrangement structure of a polygon shape including pentagon, hexagon, octagon, etc. and an elliptical arrangement structure of a plurality of laser processing dots.

[0086] FIG. 14 is a plan view showing various application examples of the laser scan processing pattern according to a modification of the present invention.

[0087] As shown in FIGS. 14(a) to 14(d), the laser scan processing pattern 225 may include a first laser scan processing pattern 225a arranged at regular or irregular intervals so as to have a shape corresponding to a through hole in a plan view, and at least one second laser scan processing pattern 225b arranged inside the first laser scan processing pattern 225a.

[0088] At this time, in FIG. 14(a), as an example, it is shown that two second laser scan processing patterns 225b are arranged inside the first laser scan processing pattern 225a so as to have an annual ring shape.

[0089] In this way, the second laser scan processing pattern 225b may have an array structure with a shape similar to that of the first laser scan processing pattern 225a.

[0090] Also, in FIG. 14(b), as an example, it is shown that the first laser scan processing pattern 225a and one second laser scan processing pattern 225b having a spiral structure are arranged inside the first laser scan processing pattern 225a.

[0091] Also, in FIG. 14(c), as an example, it is shown that the first laser scan processing pattern 225a and one second laser scan processing pattern 225b having a cross structure are arranged inside the first laser scan processing pattern 225a.

[0092] Also, in FIG. 14(d), as an example, it is shown that the first laser scan processing pattern 225a and one second laser scan processing pattern 225b that intersects radially are arranged inside the first laser scan processing pattern 225a.

[0093] As shown in FIGS. 14(b) to 14(d), the second laser scan processing pattern 225b may have an array structure with a shape different from that of the first laser scan processing pattern 225a.

[0094] As described with reference to FIGS. 14(a) to 14(d), when the laser scan processing pattern 225 is designed to include the first laser scan processing pattern 225a and at least one second laser scan processing pattern 225b, the number of dots in the laser scan processing pattern 225 can be increased, the number of transformed regions of the workpiece 210 can be further increased, the number of passages through which the etchant can penetrate more easily can be increased, and the etching time can be further reduced. As a result, not only can the etching time be significantly reduced, but also the consumption amount of the etchant can be significantly reduced, so that the productivity can be maximized.

[0095] FIG. 15 is a plan view showing various application examples of a laser scan processing pattern according to another modification of the present invention.

[0096] As shown in FIGS. 15(a) to 15(c), the laser scan processing pattern 225 can be formed to have an array structure of a straight line or a curve in which a plurality of dots are connected to each other so as to have a shape corresponding to the through hole in plan view.

[0097] At this time, as shown in FIG. 15(a), the laser scan processing pattern 225 may have a linear shape in which a plurality of dots are connected to each other so as to have a shape corresponding to the through hole in plan view. Here, the straight line is not limited to being arranged along the x-axis direction or the y-axis direction, and any straight line arranged along an arbitrary specific direction, not only a slanted line, can be applied without any restrictions.

[0098] Further, as shown in FIG. 15(b), the laser scan processing pattern 225 may have a curved shape in which a plurality of dots are connected to each other so as to have a shape corresponding to the through hole in a plan view. Here, the curve is arranged in a form bent at least once or more, and any of them can be applied as long as at least a part of it is bent.

[0099] Further, as shown in FIG. 15(c), the laser scan processing pattern 225 has a linear shape in which a plurality of dots are connected to each other so as to have a shape corresponding to the through hole in a plan view, but may have various structures such as at least two or more straight lines being connected to each other or intersecting.

[0100] As described with reference to FIGS. 15(a) to 15(c), when the laser scan processing pattern 225 is formed to have an array structure of straight lines or curves in which a plurality of dots are connected to each other so as to have a shape corresponding to the through hole, the number of dots of the laser scan processing pattern 225 can be increased, the number of regions of property change of the workpiece 210 can be further increased, the number of passages through which the etchant can penetrate more easily increases, and the etching time can be further reduced. As a result, not only can the etching time be significantly reduced, but also the consumption amount of the etchant can be significantly reduced, so that the productivity can be maximized.

[0101] Formation of Through-Holes by Wet Etching As shown in FIGS. 7, 11, and 12, in the step (S240) of forming through-holes by wet etching, the workpiece 210 on which the laser scan processing pattern (225 in FIG. 10) is formed is etched to form through-holes (TH) for each formation region of the through-holes.

[0102] More specifically, the step (S240) of forming through-holes by wet etching can be subdivided into a process of forming a plurality of etching grooves and a process of forming through-holes.

[0103] In the process of forming a plurality of etching grooves, an etchant is infiltrated into a laser scan processing pattern 225 of a workpiece 210 locally transformed by laser processing, a part of the exposed surface of the workpiece 210 is removed along the thickness direction, and a plurality of etching grooves (E) are formed.

[0104] In this stage, although wet etching using a fluorinated etchant, a non-fluorinated etchant, etc. can be used for etching, this is exemplary, and any etchant capable of etching the workpiece 210 can be used without limitation.

[0105] More preferably, the etching is preferably wet etching using an etchant containing one or more of hydrofluoric acid (HF), ammonium fluoride (NH 4 F), potassium hydroxide (KOH), and sodium hydroxide (NaOH).

[0106] Next, in the process of forming a through hole, while the etchant penetrates in the direction of the thickness center of the workpiece 210 along the plurality of etching grooves (E), a transformed dummy portion (S) of the workpiece 210 located in the space between the laser scan processing patterns 225 is allowed to naturally fall off or corrode to form a through hole (TH). For example, when the size of the shape transformed by laser processing of the dummy portion (S) is large, it naturally falls off and is removed during the etching process, and when the size of the shape transformed by laser processing is small, it can corrode naturally.

[0107] Thus, in the present invention, since the plurality of etching grooves (E) are further etched by the etchant over time, and the transformed dummy portion (S) of the workpiece 210 located between the plurality of etching grooves (E) naturally falls off or corrodes and is removed, a through hole (TH) of a desired size can be formed in a sufficiently short time compared to a general through hole forming method.

[0108] Each through-hole (TH) located in a formation region of the through-hole may be formed in the same plane. Also, each through-hole (TH) located in a formation region of the through-hole may be formed in a different plane from each other. Further, the through-holes (TH) located in the formation regions of the through-hole may be partly formed in the same plane as each other and partly formed in different planes from each other.

[0109] The through-hole (TH) of the present invention may have a diameter of 1 μm to 50 cm, but is not limited thereto. In the present invention, the diameter is not meant to mean only the maximum length of a circular through-hole (TH), but can be broadly interpreted to mean the maximum length of a through-hole (TH) such as a polygon or an ellipse.

[0110] Here, the through-hole (TH) may have a first diameter (d1) at the surface portion and a second diameter (d2) smaller than the first diameter (d1) at the inner central portion. As a result, the inner wall of the through-hole (TH) may have an acute taper angle (θ) with respect to the horizontal plane of the workpiece 210.

[0111] Also, the through-hole (TH) may have a first diameter (d1) at the surface portion and a second diameter (d2) larger than the first diameter (d1) at the inner central portion. As a result, the inner wall of the through-hole (TH) may have an obtuse taper angle (θ) with respect to the horizontal plane of the workpiece 210. Therefore, the inner wall of the through-hole (TH) may have a taper angle (θ) from acute to obtuse with respect to the horizontal plane of the workpiece 210.

[0112] That is, in a general method for forming through-holes, since the Bessel beam is irradiated for each formation region of the through-holes in the workpiece, the Bessel beam irradiated along the thickness direction of the workpiece focuses on only one processing position for laser processing. Therefore, if there are surface defects such as foreign matter or stains on the workpiece at the processing position, there is a high probability that a transformation cannot be uniformly generated inside the brittle workpiece. Ultimately, this not only causes defects in the through-holes during wet etching and inhibits the uniformity of the size or shape of a plurality of through-holes located in different formation regions of the through-holes, but also causes the size between the diameter of the surface portion of the through-hole and the diameter of the central portion of the through-hole to become non-uniform during wet etching, acting as a factor to reduce the taper angle and degrading the product quality.

[0113] In contrast, in the method for forming through-holes according to an embodiment of the present invention, the Bessel beam (BB) is sequentially irradiated in a scanning manner for each formation region of the through-holes in the workpiece 210 in a shape identical or similar to the shape of the through-hole (TH), and wet etching is performed in a state where a laser scan processing pattern 225 is formed. Therefore, it becomes possible to form a plurality of etching grooves (E) in the workpiece 210 with only the etching for the minimum time.

[0114] At this time, as time passes, the plurality of formed etching grooves (E) are further etched by the etchant, and the transformed dummy portion (S) of the workpiece 210 located between the plurality of etching grooves (E) is removed while naturally falling off or corroding. Therefore, compared with the general method for forming through-holes, it becomes possible to form through-holes (TH) of a desired size in a very short time.

[0115] Furthermore, in the method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention, one vessel beam (BB) is sequentially irradiated in a scanning manner for each formation region of the through-hole of the workpiece 210 to form a laser scanning processing pattern 225, and wet etching is performed. Therefore, due to stains, foreign matters, etc. outside the workpiece 210, some of the laser processing dots among the laser scanning processing patterns 225 located for each formation region of the through-hole are defective, and even if the shape change of the workpiece 210 is not uniformly performed in part, since other laser processing dots are arranged around, it may be possible to ensure the quality of the through-hole (TH) product without significant influence during wet etching.

[0116] As a result, in the method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention, it is possible to uniformly ensure the size between the diameter (d1) of the surface portion of the through-hole (TH) and the diameter (d2) of the central portion of the through-hole (TH) during wet etching.

[0117] Also, in a general method for forming a through-hole, one vessel beam is irradiated for each formation region of the through-hole of the workpiece to form one laser processing dot, and the through-hole is formed by gradually expanding the hole size by wet etching using an etchant for one laser processing dot. Therefore, there is a limit to varying the shape of the through-hole.

[0118] On the other hand, in the method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention, wet etching is performed using a laser scanning processing pattern 225 having an array structure separated at regular or irregular intervals, so that through-holes having substantially the same or similar shape as the laser scanning processing pattern 225 can also be varied in various shapes.

[0119] Accordingly, although the method for forming a high-speed and precise through-hole using an infrared laser according to an embodiment of the present invention can be applied to fields such as semiconductors, displays, and solar cells, it is not limited thereto. It is an obvious fact that it can be applied without limitation to any field that includes a technique for forming a through-hole in a brittle material.

[0120] Through the above process (S210 to S240), the method for forming a high-speed and precise through-hole using an infrared laser according to an embodiment of the present invention can be completed.

[0121] As discussed above, the method for forming a high-speed and precise through-hole using an infrared laser according to an embodiment of the present invention irradiates a workpiece sequentially in a scanning manner using a mirror structure to which at least one or more driving units are coupled with one modulated Bessel beam, and performs microfabrication at high speed and precision in various sizes or patterns.

[0122] Thus, in the method for forming a high-speed and precise through-hole using an infrared laser according to an embodiment of the present invention, since a scanning method of laser processing while adjusting the reflection angle of a mirror structure to which at least one or more driving units are coupled is applied, unlike a general method for forming a through-hole that only moves a stage, not only can the stabilization time be shortened to approximately 10 ms or less during laser processing, but also the size of the workpiece to be laser processed is not affected thereby.

[0123] Therefore, the method for forming a high-speed and precise through-hole using an infrared laser according to an embodiment of the present invention can perform laser processing at a speed 100 times or more higher than that of a general method for forming a through-hole, and thus the productivity can be remarkably improved.

[0124] Furthermore, the method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention can control the processing position of a workpiece at high speed and with high precision. Since wet etching can be performed while locally changing the internal properties of the workpiece so as to have the same or similar size or shape as the through-hole, the etching time can be significantly reduced, the consumption cost of the etchant can be reduced, and the quality uniformity of a plurality of through-holes formed over the entire workpiece can be improved along with productivity. As a result, in the embodiment of the present invention, since the dummy portion with changed properties of the workpiece located between a plurality of etching grooves is removed while naturally falling off or corroding, a through-hole with a desired size can be formed in a very short time compared to a general method for forming a through-hole.

[0125] Furthermore, in the method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention, one vessel beam is sequentially irradiated in a scanning manner for each formation region of the through-hole of the workpiece to form a laser scanning processing pattern, and then wet etching is performed. Therefore, in the present invention, even if some of the laser scanning processing patterns among the laser scanning processing patterns located for each formation region of the through-hole are defective due to seepage, foreign matter, etc. outside the workpiece and the change in the properties of the workpiece is not partially uniform, since other laser scanning processing patterns are arranged around them, it may be possible to ensure the quality of the through-hole product without significant influence during wet etching.

[0126] As a result, the method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention can uniformly ensure the size between the diameter of the surface portion of the through-hole and the diameter of the central portion of the through-hole when performing wet etching.

[0127] In addition, in the method for forming a high-speed precision through-hole using an infrared laser according to an embodiment of the present invention, wet etching is performed using a laser scan processing pattern having an array structure separated at regular or irregular intervals, so that through-holes having substantially the same or similar shapes as the laser scan processing pattern can also be highly variable and have various shapes.

[0128] Example Hereinafter, preferred embodiments of the present invention will be given to explain the configuration and operation of the present invention in more detail. However, this is presented as a preferred exemplification of the present invention and is not to be construed as limiting the present invention in any way.

[0129] Contents not described herein can be technically well analogized by those skilled in the art, so the description thereof will be omitted.

[0130] 1. Manufacture of test piece of through-hole Example 1 After aligning an infrared laser device above a 0.55 mm thick glass substrate, the laser beam emitted from the infrared laser device was modulated into a Bessel beam. Next, the modulated Bessel beam was sequentially irradiated in a scanning manner for each formation region of the through-hole of the glass substrate to form a laser scan processing pattern that changes the properties of the workpiece. At this time, the laser scan processing pattern was controlled to have a circular shape in which a plurality of laser processing dots were regularly separated at regular intervals.

[0131] Next, the glass substrate on which the laser scan processing pattern was formed was wet-etched for 13 minutes at a speed of 2 μm / min using a hydrofluoric acid-based etchant to form through-holes.

[0132] Example 2 Through-holes were formed in the same manner as in Example 1, except that wet etching was performed for 18 minutes at a speed of 1.5 μm / min.

[0133] Example 3 Through holes were formed in the same manner as in Example 1, except that wet etching was performed at a rate of 2.5 μm / min for 9 minutes.

[0134] Comparative Example 1 After aligning an optical modulation device for a laser vessel beam on top of a 0.65 mm thick glass substrate, the laser beam emitted from the optical modulation device for the laser vessel beam was modulated into a vessel beam. Next, the modulated vessel beam was irradiated onto each of the formation regions of the through holes in the glass substrate to form laser processing dots that change the properties of the workpiece.

[0135] Next, the glass substrate on which the laser processing dots were formed was wet-etched using a hydrofluoric acid-based etchant at a rate of 2 μm / min for 80 minutes to form through holes.

[0136] Comparative Example 2 Through holes were formed in the same manner as in Example 1, except that wet etching was performed at a rate of 2.5 μm / min for 68 minutes.

[0137] 2. Physical Property Evaluation Table 1 shows the results of evaluating the physical properties of the through-hole specimens manufactured according to Examples 1 to 3 and Comparative Examples 1 and 2.

[0138] [Table 1]

[0139] As shown in Table 1, it can be confirmed that for the through-hole specimens manufactured according to Examples 1 to 3, through holes were formed within an etching time of 20 minutes or less, based on the 0.55 mm thick glass substrate before etching.

[0140] On the other hand, for the through-hole specimens manufactured according to Comparative Examples 1 and 2, it can be confirmed that an etching time of 1 hour or more was required to form through holes, based on the 0.65 mm thick glass substrate before etching.

[0141] 2. Observation of Microstructure FIG. 16 is a process image showing the formation process of a through hole manufactured according to Comparative Example 1, and FIG. 17 is a process image showing the formation process of a through hole manufactured according to Example 1.

[0142] As shown in FIG. 16(a), in the case of Comparative Example 1, it can be confirmed that a modulated Bessel beam is irradiated onto the glass substrate 110, and laser processing dots 125 that change the properties of the glass substrate 110 are formed along the thickness direction of the glass substrate 110.

[0143] Thereafter, as shown in FIG. 16(b), it can be confirmed that an etching groove (E) is formed while the etchant gradually penetrates into the portion of the glass substrate 110 where the properties have changed and where the laser processing dot 125 is located. At this time, FIG. 16(b) shows the state after 10 minutes of wet etching. Here, when the portion of the glass substrate 110 where the properties have changed inside is etched by wet etching to form the etching groove (E), although the etching rate becomes extremely slow for the portion where the properties have changed, it can be confirmed that a part of the surface of the glass substrate 110 is also etched and removed.

[0144] Thereafter, as shown in FIGS. 16(c) and (d), it can be confirmed that a through hole (TH) that penetrates the inside of the glass substrate 110 is formed while the etching groove gradually becomes larger as wet etching is further performed over time.

[0145] At this time, FIGS. 16(c) and (d) show the state after 80 minutes of wet etching. Here, it can be confirmed that the radius size of the wet etching required to form the through hole (TH) is large and the etching time takes a long time.

[0146] On the other hand, as shown in Fig. 17(a), in the case of Example 1, the modulated Bessel beam is irradiated onto the glass substrate 210 in a scanning manner, and it can be confirmed that the laser scanning processing pattern 225 that changes the properties of the glass substrate 210 is formed so as to be regularly spaced at regular intervals along the thickness direction of the glass substrate 210.

[0147] After that, as shown in Fig. 17(b), it can be confirmed that a plurality of etching grooves (E) are formed while the etchant gradually penetrates into the portion of the glass substrate 210 where the properties have changed and where the laser scanning processing pattern 225 is located. At this time, Fig. 17(b) shows the state after 10 minutes of wet etching has elapsed. Here, when the portion of the glass substrate 210 where the internal properties have changed is etched by wet etching to form the etching grooves (E), although the etching rate is significantly slower for the portion where the properties have changed, it can be confirmed that a part of the surface of the glass substrate 210 is also etched and removed.

[0148] After that, as shown in Figs. 17(c) and (d), it can be confirmed that with the passage of time and further wet etching, the dummy portion (S) where the internal properties of the glass substrate 210 located between the plurality of etching grooves (E) have changed is removed while naturally falling off, and a through hole (TH) is formed.

[0149] At this time, Figs. 17(c) and (d) show the state after 18 minutes of wet etching has elapsed. Here, it can be seen that the size of the wet etching radius required to form the through hole (TH) is definitely small, and from this, it can be confirmed that the etching time is significantly reduced.

[0150] In the above, the embodiments of the present invention have been mainly described. However, those skilled in the art with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications. These changes and modifications can be said to belong to the present invention as long as they do not depart from the scope of the technical idea provided by the present invention. Therefore, the scope of the rights of the present invention should be determined by the claims described below.

Explanation of Reference Numerals

[0151] S210 Alignment stage of infrared laser device S220 Modulation stage of laser beam S230 Formation stage of laser scan processing pattern S240 Formation stage of through hole by wet etching

Claims

1. (a) Aligning an infrared laser device above the workpiece; (b) Modulating the laser beam emitted from the infrared laser device into a Bessel beam; (c) Performing a laser processing operation of sequentially irradiating the modulated Bessel beam onto the formation regions of the through-holes in the workpiece in a scanning manner respectively, to form a laser scanning processing pattern for locally changing the properties of the workpiece; and (d) Etching the workpiece on which the laser scanning processing pattern is formed to form through-holes for each of the formation regions of the through-holes. A method for forming a high-speed precision through-hole using an infrared laser, characterized by comprising:

2. The laser beam is an ultrashort laser having a wavelength of 900 to 1,200 nm and a pulse width of 50 femtoseconds to 50 picoseconds, The method for forming a high-speed precision through-hole using an infrared laser according to Claim 1.

3. The laser scanning processing pattern is formed in an array structure in which, in a plan view, single dots formed by the laser processing operation are separated at regular or irregular intervals so as to have a shape corresponding to the through-hole. The method for forming a high-speed precision through-hole using an infrared laser according to Claim 1.

4. The laser scanning processing pattern is in a plan view, formed in an array structure in which single dots formed by the laser processing operation are separated at regular or irregular intervals of 20 μm or less, and having at least one shape selected from among polygons including triangles, quadrilaterals, pentagons, hexagons, octagons, and star shapes, circles, and ellipses, which are shapes corresponding to the through-hole. The method for forming a high-speed precision through-hole using an infrared laser according to Claim 3.

5. The laser scanning processing pattern is in a plan view, a first laser scanning processing pattern arranged to be separated at regular or irregular intervals so as to have a shape corresponding to the through-hole, and at least one second laser scanning processing pattern arranged inside the first laser scanning processing pattern, The method for forming a high-speed precision through-hole using an infrared laser according to Claim 3.

6. The second laser scanning processing pattern is formed in an array structure having the same or different shape as the first laser scanning processing pattern. A method for forming a high-speed precision through-hole using an infrared laser according to claim 5.

7. The laser scan processing pattern is characterized in that in a plan view, it is formed to have an array structure of a straight line or a curve in which a plurality of dots are connected to each other so as to have a shape corresponding to the through-hole. A method for forming a high-speed precision through-hole using an infrared laser according to claim 1.

8. The workpiece is characterized in that it is a flat glass substrate. A method for forming a high-speed precision through-hole using an infrared laser according to claim 1.

9. In the step (c), the laser processing treatment of the scanning method is carried out by scanning using a mirror structure combined with at least one or more driving parts, the laser processing treatment of the scanning method is characterized in that the stabilization time is 10 ms or less. A method for forming a high-speed precision through-hole using an infrared laser according to claim 1.

10. In the step (d), each of the through-holes located in different formation regions of the through-hole is characterized in that they are formed in the same plane or at least a part of them are formed in planes that are different from each other. A method for forming a high-speed precision through-hole using an infrared laser according to claim 1.

11. In the step (d), the etching is characterized in that wet etching using an etchant containing at least one or more selected from fluorinated etchants and non-fluorinated etchants is used. A method for forming a high-speed precision through-hole using an infrared laser according to claim 1.

12. The step (d) is (d-1) A step of infiltrating an etchant into the laser scan processing pattern of the workpiece locally transformed by the laser processing treatment, removing a part of the exposed surface of the workpiece along the thickness direction, and forming a plurality of etching grooves; and (d-2) A step of forming a through-hole by allowing the etchant to penetrate along the plurality of etching grooves in the direction of the center of the thickness of the workpiece while naturally dropping or corroding the transformed dummy portion of the workpiece located in the space between the laser scan processing patterns. characterized by including. A method for forming a high-speed precision through-hole using an infrared laser according to claim 1.

13. The inner wall of the through-hole is characterized in that it has a taper angle from an acute angle to an obtuse angle with respect to the horizontal plane of the workpiece. A method for forming a high-speed precision through-hole using an infrared laser according to claim 12.

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