Ditch forming device

Abstract

A groove forming device capable of performing a groove forming process with high efficiency and speed is provided. [Solution] The groove forming device 10 includes a laser light source 110 that emits a laser beam LB, a multi-beam generator 140 that divides the laser beam LB into multiple sub-laser beams, a focusing lens unit 150 that focuses the multiple sub-laser beams, a first telecentric lens 210 provided between the multi-beam generator and the focusing lens unit, and a second telecentric lens 220 provided between the first telecentric lens and the focusing lens unit.

Description

[Technical Field]

[0001] The present invention relates to a groove forming device. [Background technology]

[0002] Generally, laser processing refers to a method of using a focusing lens to focus a laser beam into one focal point and irradiating the focal point onto the surface or inside of a processing target.

[0003] To form the groove, multiple beams are moved continuously along a single machining path to machine the workpiece. If the spacing between the multiple beams is too small, a heat affected zone (HAZ) will be formed in the workpiece around the groove, resulting in an uneven groove bottom, excessive bottom overmachining, and excessive slope on the sidewalls of the groove. Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved is to provide a groove forming apparatus that can use sub-laser beams that are split at the maximum angle from a multi-beam generator for a groove forming process, thereby providing a groove forming apparatus that can perform a groove forming process with high efficiency and speed.

[0005] The problem to be solved is to provide a groove forming device that forms grooves having a required shape (e.g., a shape in which no HAZ occurs, the bottom surface is uniform, and the width of the bottom of the groove is 75% or more of the width of the top).

[0006] However, the problem to be solved is not limited to the above disclosure. [Means for solving the problem]

[0007] In one aspect, a groove forming device may be provided that includes a laser light source that emits a laser beam, a multi-beam generator that divides the laser beam into a plurality of sub-laser beams, a focusing lens unit that focuses the plurality of sub-laser beams on an object to be processed, a first telecentric lens provided between the multi-beam generator and the focusing lens unit, and a second telecentric lens provided between the first telecentric lens and the focusing lens unit.

[0008] The back focal plane of the first telecentric lens and the front focal plane of the second telecentric lens may overlap each other.

[0009] The first telecentric lens may have a size that accommodates the plurality of sub-laser beams split at a maximum angle from the multi-beam generator.

[0010] The maximum angle is also ±3°.

[0011] The multi-beam generator can divide the plurality of sub-laser beams so that the intervals between the plurality of sub-laser beams are 50 μm or more on the object to be processed.

[0012] On the workpiece, the intervals between the plurality of sub-laser beams are also the same.

[0013] At least two of the intervals between the plurality of sub-laser beams on the workpiece may be different from each other.

[0014] The plurality of sub-laser beams may be arranged symmetrically on the workpiece.

[0015] The sub-laser beams may have the same intensity.

[0016] At least two of the plurality of sub-laser beams may have different intensity values.

[0017] Although the optical system may further include a scan head, the focusing lens unit may be disposed within the scan head, and the multi-beam generator, the first telecentric lens, and the second telecentric lens may be disposed outside the scan head.

[0018] The processing apparatus may further include a stage for supporting the object to be processed, and the stage may adjust the positions at which the plurality of sub-laser beams are focused on the object to be processed.

[0019] In one aspect, a groove forming device may be provided that includes a laser light source that emits a laser beam, a multi-beam generator that divides the laser beam into a plurality of sub-laser beams, and a focusing lens unit that focuses the plurality of sub-laser beams on an object to be processed, wherein the focusing lens unit is spaced apart from the multi-beam generator so as to accommodate the plurality of sub-laser beams that are divided at the maximum angle from the multi-beam generator.

[0020] The maximum angle is also ±3°.

[0021] The multi-beam generator can divide the plurality of sub-laser beams so that the intervals between the plurality of sub-laser beams are 50 μm or more on the object to be processed. [Effects of the Invention]

[0022] The present disclosure provides a groove forming apparatus that can utilize sub-laser beams split at the maximum angle from a multi-beam generator for a groove forming process, thereby enabling a groove forming process to be performed with high efficiency and speed.

[0023] The present disclosure can provide a groove forming device that forms grooves having a desired shape (e.g., a shape in which HAZ generation is minimized, the bottom surface is not excessively machined and is uniformly machined, and the bottom width of the groove is 75% or more of the top width).

[0024] However, the effects of the invention are not limited to the above disclosure. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a conceptual diagram of a groove forming apparatus in accordance with an exemplary embodiment; [Figure 2] FIG. 2 is a conceptual diagram of the focusing lens unit of FIG. 1. [Figure 3] 1 is a conceptual diagram of a groove forming apparatus in accordance with an exemplary embodiment; [Figure 4] FIG. 2 is a plan view of an object to be processed to explain a sub-laser beam irradiated onto the object in accordance with an exemplary embodiment. [Figure 5] FIG. 2 is a plan view of an object to be processed to explain a sub-laser beam irradiated onto the object in accordance with an exemplary embodiment. [Figure 6] FIG. 10 shows grooves machined by five sub-laser beams with a beam spacing of 45 μm. [Figure 7] FIG. 10 shows grooves machined by eight sub-laser beams with a beam spacing of 25 μm. [Figure 8] FIG. 10 shows grooves machined by five sub-laser beams with a beam spacing of 150 μm. [Figure 9] FIG. 10 shows grooves machined by eight sub-laser beams with a beam spacing of 200 μm. [Figure 10] 10 is a graph illustrating the relative intensities of sub-laser beams according to an example embodiment. [Figure 11] 10 is a graph illustrating the relative intensities of sub-laser beams according to an example embodiment. [Figure 12] 1A and 1B are conceptual diagrams for explaining the positional relationship between an object to be processed and a focusing lens unit according to an exemplary embodiment. [Figure 13] 1A and 1B are conceptual diagrams for explaining the positional relationship between an object to be processed and a focusing lens unit according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals refer to the same components, and the size and thickness of each component may be exaggerated for clarity.

[0027] Terms including ordinal numbers, such as "first" and "second," may be used to describe various elements, but the elements are not limited by the terms. These terms are used only to distinguish one element from another. For example, a first element may also be named a second element, and similarly, the second element may also be named the first element, without departing from the scope of the present invention. The term "and / or" includes a combination of multiple associated items or any one item of multiple associated items.

[0028] 1 is a conceptual diagram of a groove forming apparatus according to an exemplary embodiment, and FIG. 2 is a conceptual diagram of a focusing lens unit of FIG.

[0029] 1, a groove forming apparatus 10 may be provided, including a laser light source 110, a collimator 120, a beam expander 130, a multi-beam generator 140, a telecentric lens unit 200, a focusing lens unit 150, and a stage 400. The laser light source 110 may emit a laser beam LB. For example, the laser beam LB may be a pulsed laser. The laser light source 110 may provide the laser beam LB to the collimator 120. The laser beam LB emitted from the laser light source 110 may be diverging light. For example, the laser beam LB may have a width that widens along the traveling direction until it reaches the collimator 120.

[0030] The collimator 120 may convert the laser beam LB into parallel light. The laser beam LB may have a substantially constant width after passing through the collimator 120. The width of the laser beam LB is also the width of the laser beam LB along a direction substantially perpendicular to the traveling direction of the laser beam LB. The collimator 120 may include a single lens or a combination of multiple lenses. The collimator 120 may provide the parallel laser beam LB to the beam expander 130.

[0031] The beam expander 130 may expand the width of the laser beam LB. The beam expander 130 may also be an optical system including multiple lenses. The beam expander 130 may provide the laser beam LB having the expanded width to the multi-beam generator 140.

[0032] The multi-beam generator 140 may split the laser beam LB into sub-laser beams SLB. Although three sub-laser beams SLB are illustrated, this is for illustrative purposes only. In other examples, more than three sub-laser beams SLB may be provided. For example, the multi-beam generator 140 may include at least one of a diffractive optical element (DOE), a cube beam splitter, and a prism beam splitter. For simplicity, the multi-beam generator 140 will be described below as including a diffractive optical element. The sub-laser beams SLB may also be formed by diffracting the laser beam LB by the multi-beam generator 140. In one example, the sub-laser beams SLB may be symmetric. For example, the centrally located sub-laser beam SLB may also be a 0th-order diffraction beam. The sub-laser beams SLB arranged along a direction away from the centrally located sub-laser beam SLB may also be ±1st-order diffraction beams, ±2nd-order diffraction beams, ..., ±nth-order diffraction beams. The + and - symbols may indicate directions away from the central sub-laser beam SLB. For example, a +1st order diffraction beam, a +2nd order diffraction beam, ..., a +nth order diffraction beam may be arranged in this order on one side of the central sub-laser beam SLB, and a -1st order diffraction beam, a -2nd order diffraction beam, ..., a -nth order diffraction beam may be arranged in this order on the other side. In one example, all of the sub-laser beams SLB emitted from the multi-beam generator 140 may be used in the groove forming process. In another example, lower order diffraction beams among the sub-laser beams SLB emitted from the multi-beam generator 140 may be used in the groove forming process. The use of the lower order diffraction beams in the groove forming process will be described later.

[0033] The maximum value of the split angle 142 (hereinafter referred to as the maximum angle) at which the sub-laser beams SLB used in the groove formation process are split by the multi-beam generator 140 is approximately ±3°. This maximum angle is also the angle between the chief ray of the zeroth-order diffracted beam and the chief ray of the beam having the highest order. For example, if the highest order is ±3°, the angles between the chief ray of the ±3rd-order diffracted beam and the chief ray of the zeroth-order diffracted beam are also ±3°. The angles between adjacent sub-laser beams SLB can be determined as needed. Conditions related to the patterns formed on the diffractive optical element (e.g., the distance between the patterns, the pattern arrangement, the pattern size, etc.) can be determined so that the sub-laser beams SLB are split at the required angles. Each of the sub-laser beams SLB is a parallel beam having a certain width. The multi-beam generator 140 may provide the sub-laser beams SLB to the telecentric lens unit 200.

[0034] The telecentric lens unit 200 may transmit the sub-laser beam SLB to the focusing lens unit 150. The telecentric lens unit 200 may function as a relay lens that increases the length of the optical system. The telecentric lens unit 200 may also include a first telecentric lens 210 and a second telecentric lens 220 that are arranged along the optical path of the sub-laser beam SLB in a direction away from the multi-beam generator 140.

[0035] The first telecentric lens 210 may have an infinity focal length on the multi-beam generator 140 side and a first focal length 214 on the second telecentric lens 220 side. In other words, the front focal length of the first telecentric lens 210 is infinity, and the rear focal length thereof is also the first focal length 214. A first focal plane 212 may be located at a position spaced apart by the first focal length 214 from the center of the first telecentric lens 210 on the second telecentric lens 220 side. The first telecentric lens 210 may focus the sub-laser beam SLB onto the first focal plane 212. In one example, the chief rays of the sub-laser beam SLB that have passed through the first telecentric lens 210 are also substantially parallel to each other.

[0036] The second telecentric lens 220 may have a second focal length 224 on the first telecentric lens 210 side and an infinity focal length on the focusing lens unit 150 side (described later). In other words, the front focal length of the second telecentric lens 220 is also the second focal length 224, and the rear focal length is also infinity. A second focal plane 222 may be located at a position spaced apart by the second focal length 224 from the center of the second telecentric lens 220 on the first telecentric lens 210 side. The second focal plane 222 may substantially overlap with the first focal plane 212. The sub-laser beam SLB focused on the first focal plane 212 (i.e., the second focal plane 222) by the first telecentric lens 210 may diverge after passing through the first focal plane 212. In other words, the width of the sub-laser beam SLB may become narrower as it passes through the first telecentric lens 210 and approaches the first focal plane 212, and may become wider as it passes through the first focal plane 212 and approaches the second telecentric lens 220. The sub-laser beam SLB may be converted into a parallel beam having a certain width by the second telecentric lens 220. The second telecentric lens 220 may provide the sub-laser beam SLB to the focusing lens unit 150.

[0037] In one example, the first telecentric lens 210 and the second telecentric lens 220 are substantially identical to one another. For example, the first focal length 214 and the second focal length 224 are substantially identical to one another. In one example, the first telecentric lens 210 and the second telecentric lens 220 are different from one another. For example, the first focal length 214 and the second focal length 224 are different. The first telecentric lens 210 and the second telecentric lens 220 may include a single lens or a compound lens.

[0038] In one example, low-order diffraction beams (e.g., 0th-order diffraction beam, ±1st-order diffraction beam, ±2nd-order diffraction beam, ±3rd-order diffraction beam) may be selectively used in the groove forming process. In other words, high-order diffraction beams (e.g., 4th-order or higher diffraction beams) are not used in the groove forming process. In one example, to prevent sub-laser beams SLB corresponding to unwanted high-order diffraction beams from being used in the groove forming process, the groove forming apparatus 10 may further include at least one of a first mask (not shown) and a second mask (not shown) that block high-order diffraction beams.

[0039] The first mask may be provided on an optical path between the multi-beam generator 140 and the first telecentric lens 210. The first mask may block high-order diffraction beams, which are not used in the groove forming process, from being provided to the first telecentric lens 210 among the sub-laser beams SLB formed by the multi-beam generator 140. For example, the first mask may also be an aperture stop.

[0040] The second mask may be provided on the optical path between the first telecentric lens 210 and the second telecentric lens 220. For example, the second mask may be located at the first back focal plane (or the second front focal plane). The second mask may block high-order diffracted beams, which are not used in the groove forming process, from being provided to the second telecentric lens 220, among the sub-laser beams that have passed through the first telecentric lens 210. For example, the second mask may also be a spatial filter.

[0041] When the first mask and the second mask are provided simultaneously, they can block more than 99% of the high-order diffracted beams that are not used in the groove forming process.

[0042] The focusing lens unit 150 may focus the sub-laser beam SLB on the workpiece 300. The focusing lens unit 150 may include a single lens or a compound lens. For example, the focusing lens unit 150 may include an f50 telecentric lens with a focal length of 50 mm. As shown in FIG. 2, the focusing lens unit 150 may be disposed within the scan head 152. The scan head 152 may include components other than the focusing lens unit 150. For example, the scan head 152 may further include a mirror for transmitting the sub-laser beam SLB provided from the telecentric lens unit 200 to the focusing lens unit 150 and / or a galvanic scanner for adjusting the position on the workpiece 300 where the sub-laser beam SLB is irradiated. The spacing between the sub-laser beams SLB on the workpiece 300 is also referred to as the beam spacing. The beam spacing may be 50 μm or more. For example, the beam spacing may be 50 μm to 1,000 μm.

[0043] The stage 400 may face the focusing lens unit 150. The stage 400 may support the workpiece 300 and adjust the position of the workpiece 300. The stage 400 may move the workpiece 300 along the horizontal and vertical directions. For example, the horizontal direction is a direction parallel to the top surface of the stage 400, and the vertical direction is a direction perpendicular to the top surface of the stage 400. While the stage 400 moves the workpiece 300, the sub-laser beam SLB may be irradiated onto the workpiece 300, thereby performing a groove formation process.

[0044] If necessary, optical elements (for example, mirrors) for changing the optical path may be disposed between the aforementioned optical elements.

[0045] When the sub-laser beams SLB split by the multi-beam generator 140 at the maximum angle are used in the groove forming process, the efficiency and speed of the groove forming process are increased. For example, when the sub-laser beams SLB are split at the maximum angle (e.g., ±3°), the spacing between the outermost pair of sub-laser beams SLB on the workpiece 300 is a maximum of 4,000 μm, and the beam spacing is required to be 500 μm or more, a maximum of nine sub-laser beams SLB can be used in the groove forming process. In this case, if the optical element that accommodates the sub-laser beams SLB emitted from the multi-beam generator 140 cannot accommodate all of the sub-laser beams SLB emitted from the multi-beam generator 140, fewer than nine sub-laser beams SLB can be used in the groove forming process. In this case, the efficiency and speed of the groove forming process are reduced.

[0046] The groove forming device 10 of the present disclosure can increase the efficiency and speed of the groove forming process by using the sub-laser beam SLB split at the maximum angle by the multi-beam generator 140 for the groove forming process. In addition, the present disclosure can increase the degree of freedom in the optical system configuration by using the first telecentric lens 210 and the second telecentric lens 220.

[0047] 3 is a conceptual diagram of a groove forming device according to an exemplary embodiment. For simplicity of explanation, only the differences from what was explained with reference to FIGS.

[0048] Referring to FIG. 3, a groove forming apparatus 11 may be provided. Unlike the focusing lens unit 150 of the groove forming apparatus 10 described with reference to FIGS. 1 and 2, the focusing lens unit 150 of the groove forming apparatus 11 may be disposed immediately adjacent to the multi-beam generator 140. The sub-laser beams SLB may be emitted from the multi-beam generator 140 and provided immediately to the focusing lens unit 150. A telecentric lens unit 200 is not provided. The maximum split angle of the sub-laser beams SLB that the focusing lens unit 150 can accommodate also varies depending on the distance between the focusing lens unit 150 and the multi-beam generator 140. The farther the focusing lens unit 150 is from the multi-beam generator 140, the smaller the maximum split angle of the sub-laser beams SLB that the focusing lens unit 150 can accommodate. The focusing lens unit 150 may be disposed adjacent to the multi-beam generator 140 so as to accommodate all of the sub-laser beams SLB divided into the maximum angle (e.g., ±3°) in the multi-beam generator 140. For example, if the focusing lens unit 150 includes an f50 telecentric lens with a focal length of 50 mm and an entrance pupil diameter (EPD) of 24 mm, the separation distance between the focusing lens unit 150 and the multi-beam generator 140 is 10 mm or less.

[0049] The groove forming apparatus 11 of the present disclosure utilizes the sub-laser beams SLB split at the maximum angle by the multi-beam generator 140 for the groove forming process, thereby increasing the efficiency and speed of the groove forming process.

[0050] In the following, a groove forming method using a sub-laser beam SLB will be described.

[0051] FIG. 4 is a plan view of an object to be processed for explaining sub-laser beams irradiated onto the object according to an exemplary embodiment.

[0052] Referring to FIG. 4 , seven sub-laser beams SLB may be irradiated onto the workpiece 300. In one example, the stage 400 may move the workpiece 300 while the sub-laser beams SLB are being irradiated. For example, the stage 400 may move the workpiece 300 in a first direction DR1. As a result, grooves GR may be formed in the workpiece 300. As described above, the number of sub-laser beams SLB may be determined as needed. The seven sub-laser beams SLB may also be a 0th-order diffraction beam, ±1st-order diffraction beams, ±2nd-order diffraction beams, and ±3rd-order diffraction beams. For example, the central sub-laser beam SLB is a 0th-order diffraction beam, and the sub-laser beams SLB corresponding to +1st-order diffraction beam, +2nd-order diffraction beam, and +3rd-order diffraction beam may be sequentially arranged from the central sub-laser beam SLB along a first direction DR1, and the sub-laser beams SLB corresponding to -1st-order diffraction beam, -2nd-order diffraction beam, and -3rd-order diffraction beam may be sequentially arranged from the central sub-laser beam SLB along a second direction DR2 opposite to the first direction DR1. In one example, the distance D between a pair of outermost sub-laser beams SLB (i.e., ±3rd-order diffraction beams) among the sub-laser beams SLB may be T The length D of each of the sub-laser beams SLB may be 100 μm to 4,000 μm. Each of the sub-laser beams SLB may extend along a third direction DR3 intersecting the first direction DR1 and the second direction DR2. For example, the length D of each of the sub-laser beams SLB along the third direction DR3 may be L The width D of the sub-laser beam SLB is 30 to 200 μm. W The width D of the sub-laser beam SLB is 5 to 20 μm. W is also the width of the sub-laser beam SLB along the first direction DR1 or the second direction DR2.

[0053] The sub-laser beams SLB are spaced at substantially the same distance D b In the following, the spacing between the sub-laser beams SLB is defined as the beam spacing D b The beam spacing D bIf the sub-laser beam SLB is less than 50 μm, the groove GR will not have the required shape. For example, latent heat from the sub-laser beam SLB accumulates, causing excessive deformation of the workpiece 300 around the groove GR, resulting in an excessively large heat-affected zone (HAZ), which may result in an uneven bottom surface of the groove GR or excessive machining, or the width of the bottom of the groove GR being 75% or less of the width at the top, resulting in a low taper ratio (steepness). Furthermore, if the sub-laser beam SLB processes the workpiece 300 at an excessively short interval, dust generated by the sub-laser beam SLB will accumulate around the top of the groove GR. In other words, the processability of the groove GR may be reduced.

[0054] The groove forming devices 10 and 11 of the present disclosure have a beam spacing D of 50 μm or more. b The groove GR can be formed by the sub-laser beam SLB having a beam interval D b The beam spacing D between the sub-laser beams SLB is 50 μm to 1,000 μm. b is wide, so the beam spacing D b Unlike when the sub-laser beam SLB is less than 50 μm, the accumulation of latent heat by the sub-laser beam SLB is reduced, and the occurrence of HAZ can be minimized. As a result, the bottom surface of the groove GR is processed uniformly without being excessive, the bottom width of the groove GR becomes 75% or more of the top width, and the taper ratio can be increased. In other words, the groove forming apparatus 10, 11 of the present disclosure can form grooves GR having a required shape.

[0055] When the workpiece includes multiple materials with different thermal reactivity, a sub-laser beam SLB having a beam spacing that can perform the required quality of processing on one material cannot perform the required quality of processing on a different material. That is, processing the above-mentioned different materials may result in excessive HAZ, the sidewalls of the groove GR having a low taper ratio, and the bottom may be uneven and excessively processed. The groove forming device 10 of the present disclosure can perform the processing on a different material with a beam spacing D of 50 μm or more. bSince the processing is performed using the sub-laser beam SLB having the above-described characteristics, it is possible to perform processing of a plurality of materials having different heat reactivity with the required quality. In other words, the groove forming device 10 of the present disclosure can achieve uniform processing performance for a plurality of different materials.

[0056] 5 is a plan view of an object to be processed for explaining the sub-laser beams irradiated on the object according to an exemplary embodiment. For the sake of brevity, the substantially same content as that described with reference to FIG. 4 will not be described.

[0057] 5, seven sub-laser beams SLB may be provided. Except for the beam spacing, the sub-laser beams SLB are substantially the same as the sub-laser beams SLB described with reference to FIG.

[0058] Unlike the case described with reference to FIG. 4, the sub-laser beams SLB can be arranged at different intervals. The beam spacing between the sub-laser beams SLB can be set to +1 beam spacing +D b1 , +2 beam spacing +D b2 , +3 beam spacing +D b3 , -1 beam spacing -D b1 , -2 beam spacing -D b2 and -3 beam spacing -D b3 The sub-laser beams SLB corresponding to the ±1st order diffraction beams, ±2nd order diffraction beams, and ±3rd order diffraction beams may be arranged symmetrically around the central sub-laser beam SLB corresponding to the 0th order diffraction beam. +1 beam spacing +D b1 , +2 beam spacing +D b2 and +3 beam spacing +D b3 are -1 and -D, respectively. b1 , -2 beam spacing -D b2 and -3 beam spacing -D b3 +1 beam spacing +D b1 , +2 beam spacing +D b2 and +3 beam spacing +D b3 (or -1 beam spacing -D b1 , -2 beam spacing -Db2 and -3 beam spacing -D b3 ) can be different. b1 , +2 beam spacing +D b2 , +3 beam spacing +D b3 , -1 beam spacing -D b1 , -2 beam spacing -D b2 and -3 beam spacing -D b3 Each of these is 50 μm or more. For example, +1 beam spacing +D b1 , +2 beam spacing +D b2 , +3 beam spacing +D b3 , -1 beam spacing -D b1 , -2 beam spacing -D b2 and -3 beam spacing -D b3 Each of these is 50 μm to 1,000 μm. b1 , +2 beam spacing +D b2 and +3 beam spacing +D b3 (or -1 beam spacing -D b1 , -2 beam spacing -D b2 and -3 beam spacing -D b3 ) may be determined as needed.

[0059] The groove forming devices 10 and 11 of the present disclosure have a +1 beam spacing +D b1 , +2 beam spacing +D b2 , +3 beam spacing +D b3 , -1 beam spacing -D b1 , -2 beam spacing -D b2 and -3 beam spacing -D b3 Since the groove GR is formed by the sub-laser beam SLB having the above-described wavelength, the latent heat generated by the sub-laser beam SLB that performed the previous processing can be sufficiently small when the next sub-laser beam SLB immediately performs the processing. As a result, the groove forming devices 10 and 11 of the present disclosure can form the groove GR having a required shape (for example, a shape in which the generation of HAZ is minimized, the bottom surface is not excessive but is processed uniformly, and the width of the bottom of the groove GR is 75% or more of the width of the top).

[0060] In one example, a groove GR may be formed to cut a workpiece. Ideally, the side of the groove GR should be as close to vertical as possible. The greater the difference between the top and bottom widths of the groove GR, the more gently inclined the side of the groove GR. After groove formation using a laser (grooving), the workpiece is cut with a blade along the groove GR. The more gently the side slope of the groove GR, the more likely it is that the rotating blade will contact the sidewall of the groove while being inserted to the bottom of the groove, causing cracks. Therefore, the groove GR may be processed so that the bottom width is 75% or more of the top width of the groove GR. Alternatively, taking into account the depth of the groove GR, the groove GR may be processed so that the average slope of both sidewalls is 2 or more. The average slope of both sidewalls can be expressed as "groove depth / (top width of groove - bottom width of groove) / 2."

[0061] A cutting process of a workpiece was carried out using the grooves GR formed by the groove forming devices 10 and 11 of the present disclosure. The blade used in this experiment had a width of 30 μm, and taking into account a blade processing tolerance of ±5 μm, the groove GR was specified to have a lower width of 40 μm or less and an upper width of 52 μm or less. The energy of each beam used in the experiment was 5 W.

[0062] In processing non-metallic pattern wafers, the beam spacing D b , +D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 is 50 μm or more, the difference between the upper width and the lower width of the groove GR is 12 μm or less, and the beam spacing D b ,+D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 When the average slope of the sidewalls is 40 μm or more, the average slope of the sidewalls is 2 or more.

[0063] In addition, in processing metal pattern wafers, the beam spacing D b ,+Db1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 When the difference between the upper and lower widths of the groove GR is 12 μm or less, and the beam spacing D b ,+D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 When the average slope of the sidewalls is 20 μm or more, the average slope of the sidewalls is 2 or more.

[0064] That is, beam spacing D b ,+D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 When the thickness is 50 μm or more, the ratio of the bottom width to the top width of the groove GR and the average slope of both side walls can be satisfied in processing both non-metallic pattern wafers and metallic pattern wafers.

[0065] In addition, the HAZ reduces the strength of the workpiece, and as the amount of the HAZ increases and the height of the HAZ increases, the difference between the upper and lower widths of the groove GR also increases. Therefore, the lower the height of the HAZ, the better. Experimental results showed that the beam spacing D b ,+D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 It was confirmed that the wider the beam spacing D, the lower the height of the HAZ. b ,+D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 The wider the beam spacing D, the more advantageous it is in preventing the occurrence of HAZ. b ,+D b1 ,+D b2,+D b3 ,-D b1 ,-D b2 ,-D b3 When the beam spacing D was smaller than 40 μm, the width of the HAZ increased rapidly. b ,+D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 is greater than 40 μm, the height of the HAZ is reduced, but in non-metallic pattern wafers, the beam spacing D b ,+D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 When the beam spacing D is greater than 40 μm, the height of the HAZ is reduced sharply. b ,+D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 When the HAZ height is 40 μm or more, advantageous processing results can be obtained in terms of the height and width of the HAZ in both non-metallic pattern wafers and metallic pattern wafers.

[0066] Considering the above experimental results, we conclude that the beam spacing D b ,+D b1 ,+D b2 ,+D b3 ,-D b1 ,-D b2 ,-D b3 When the taper ratio is 50 μm or more, satisfactory processing results can be obtained in terms of the taper ratio, the slope, and the height and width of the HAZ, regardless of the material of the object 300 to be processed.

[0067] Figure 6 shows a groove machined by five sub-laser beams with a beam spacing of 45 μm, and Figure 7 shows a groove machined by eight sub-laser beams with a beam spacing of 25 μm.

[0068] 6 and 7, a plan view of the groove GR is superimposed on a cross-sectional shape graph of the groove GR. The groove GR has a large HAZ 1 and an over-machined lower region 2. The bottom surface of the groove GR has low uniformity.

[0069] Figure 8 shows a groove machined by five sub-laser beams with a beam spacing of 150 μm, and Figure 9 shows a groove machined by eight sub-laser beams with a beam spacing of 200 μm.

[0070] 8 and 9, a plan view of the groove GR is superimposed on a cross-sectional shape graph of the groove GR. Unlike the groove GR shown in FIGS. 6 and 7, the groove GR has a small HAZ 1 and does not have an overly machined lower region. The groove GR has a uniformly machined bottom surface.

[0071] FIG. 10 is a graph illustrating the relative intensities of sub-laser beams according to an example embodiment.

[0072] 10, the sub-laser beams SLB may have substantially the same intensity. The sub-laser beams SLB corresponding to the 0th order diffraction beam, ±1st order diffraction beams, ±2nd order diffraction beams, and ±3rd order diffraction beams shown in FIGS. 4 and 5 are labeled 0, ±1, ±2, and ±3, respectively. The absolute intensity of the sub-laser beams SLB may be determined as needed. For example, the absolute intensity of the sub-laser beams SLB may be determined depending on the type of workpiece 300 and / or the beam spacing between the sub-laser beams SLB.

[0073] The groove forming devices 10 and 11 of the present disclosure have a beam spacing D of 50 μm or more. b Since the groove GR is formed using the sub-laser beam SLB having the above-mentioned structure, the groove GR can be formed with a desired shape (e.g., a shape in which HAZ generation is minimized, the bottom surface is not excessively machined and is uniformly processed, and the width of the bottom of the groove is 75% or more of the width of the top).

[0074] FIG. 11 is a graph illustrating the relative intensities of sub-laser beams according to an example embodiment.

[0075] Referring to FIG. 11, the sub-laser beams SLB may have different intensities. The sub-laser beams SLB corresponding to the 0th order diffraction beam, ±1st order diffraction beams, ±2nd order diffraction beams, and ±3rd order diffraction beams shown in FIGS. 4 and 5 are labeled 0, ±1, ±2, and ±3, respectively. The intensities of the sub-laser beams SLB corresponding to the 0th order diffraction beam and ±2nd order diffraction beam are half the intensities of the sub-laser beams SLB corresponding to the ±1st order diffraction beam and ±3rd order diffraction beam. However, the relative intensities of the sub-laser beams SLB are not limited to those shown in the drawings and may be determined as needed. The absolute intensities of the sub-laser beams SLB may be determined as needed. For example, the absolute intensities of the sub-laser beams SLB may be determined depending on the type of workpiece 300 and / or the beam spacing between the sub-laser beams SLB.

[0076] The groove forming devices 10 and 11 of the present disclosure have a beam spacing D of 50 μm or more. b Since the groove GR is formed using the sub-laser beam SLB having the above-mentioned structure, the groove GR can be formed with a desired shape (e.g., a shape in which HAZ generation is minimized, the bottom surface is not excessively machined and is uniformly processed, and the width of the bottom of the groove is 75% or more of the width of the top).

[0077] 12 and 13 are conceptual diagrams for explaining the positional relationship between the workpiece and the focusing lens unit according to an exemplary embodiment. For the sake of simplicity, details that are substantially the same as those described with reference to FIGS. 1 and 2 and those described with reference to FIG. 3 will not be described.

[0078] 12 and 13, the focusing lens unit 150 may focus the sub-laser beam SLB on the workpiece 300 disposed on the stage 400. The focusing lens unit 150 may have a first image plane IP1 located between the focal point FP and the focusing lens unit 150, and a second image plane IP2 located on the opposite side of the first image plane IP1 from the focal point FP.

[0079] 12, the focusing lens unit 150 may be arranged so that the focal point of the focusing lens unit 150 is located within the workpiece 300. For example, the focusing lens unit 150 may be arranged so that the first image plane IP1 is located on the surface of the workpiece 300. In this case, the workpiece 300 may be processed by the sub-laser beam SLB at the first image plane IP1.

[0080] 13, the focusing lens unit 150 may be arranged so that the focal point of the focusing lens unit 150 is located between the workpiece 300 and the focusing lens unit 150. For example, the focusing lens unit 150 may be arranged so that the second image plane IP2 is located on the surface of the workpiece 300. In this case, the workpiece 300 may be processed by the sub-laser beam SLB at the second image plane IP2.

[0081] The position of the focusing lens unit 150 can be determined as needed.

[0082] The sidewalls of the groove formed by the sub-laser beam SLB in the first image plane IP1 may be more inclined than the sidewalls of the groove formed by the sub-laser beam SLB in the second image plane IP2. The image plane on which the groove is formed by the sub-laser beam SLB can be determined depending on the desired groove shape.

[0083] The groove forming devices 10 and 11 of the present disclosure have a beam spacing D of 50 μm or more. bSince the groove GR is formed using the sub-laser beam SLB having the above-mentioned structure, the groove GR can be formed with a desired shape (e.g., a shape in which HAZ generation is minimized, the bottom surface is not excessively machined and is uniformly processed, and the width of the bottom of the groove is 75% or more of the width of the top).

[0084] The above description of the embodiments of the technical concept of the present invention provides examples for explaining the technical concept of the present invention. Therefore, the technical concept of the present invention is not limited to the above embodiments, and it is obvious that various modifications and changes can be made by those skilled in the art within the technical concept of the present invention, such as by combining and implementing the above embodiments.

Claims

1. a laser light source that emits a laser beam; a multi-beam generator that splits the laser beam into a plurality of sub-laser beams; a focusing lens unit that focuses the plurality of sub-laser beams onto a processing target; a first telecentric lens provided between the multi-beam generator and a focusing lens unit; a second telecentric lens provided between the first telecentric lens and the focusing lens unit.

2. The groove forming device of claim 1 , wherein a rear focal plane of the first telecentric lens and a front focal plane of the second telecentric lens overlap each other.

3. The groove forming apparatus of claim 1 , wherein the first telecentric lens has a size that accommodates the plurality of sub-laser beams that are split at a maximum angle from the multi-beam generator.

4. The groove forming device of claim 3 , wherein the maximum angle is ±3°.

5. 2. The groove forming device according to claim 1, wherein the multi-beam generator divides the plurality of sub-laser beams so that the intervals between the plurality of sub-laser beams on the object to be processed are 50 μm or more.

6. The groove forming device according to claim 1 , wherein the intervals between the plurality of sub-laser beams on the workpiece are the same.

7. The groove forming apparatus according to claim 1 , wherein at least two of the intervals between the plurality of sub-laser beams on the workpiece are different from each other.

8. The groove forming device according to claim 1 , wherein the plurality of sub-laser beams are arranged symmetrically on the workpiece.

9. The groove forming apparatus according to claim 1 , wherein the plurality of sub-laser beams have the same intensity.

10. The groove forming apparatus of claim 1 , wherein at least two of the plurality of sub-laser beams have different intensities.

11. Further comprising a scan head, the focusing lens unit is disposed within the scan head; The groove forming device according to claim 1 , wherein the multi-beam generator, the first telecentric lens, and the second telecentric lens are disposed outside the scan head.

12. Further includes a stage for supporting the object to be processed, The groove forming device according to claim 1 , wherein the stage adjusts the positions at which the plurality of sub-laser beams are focused on the object to be processed.

13. a laser light source that emits a laser beam; a multi-beam generator that splits the laser beam into a plurality of sub-laser beams; a focusing lens unit that focuses the plurality of sub-laser beams onto a processing target, The focusing lens unit is spaced apart from the multi-beam generator to accommodate the plurality of sub-laser beams split at a maximum angle from the multi-beam generator.

14. The groove forming device of claim 13, wherein the maximum angle is ±3°.

15. 14. The groove forming device according to claim 13, wherein the multi-beam generator divides the plurality of sub-laser beams so that intervals between the plurality of sub-laser beams are 50 μm or more on the object to be processed.

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