Laser dicing device

Abstract

This laser dicing device comprises: a laser light source that outputs a beam; at least one lens provided on the optical path of the beam; a diffractive optical element that is provided in a convergence / divergence region, which is a region on the optical path where the beam converges or diverges due to the action of the lens, and that splits the beam; and a movement mechanism that moves the diffractive optical element along the optical axis of the beam in the convergence / divergence region.

Description

Laser dicing device

[0001] The disclosed technology relates to a laser dicing apparatus.

[0002] The following technologies are known regarding laser dicing apparatuses. For example, Japanese Patent Publication No. 2014-588 describes a laser processing apparatus comprising: a laser beam emitting means for emitting a laser beam; a concentrator for focusing the laser beam emitted from the laser beam emitting means and irradiating a workpiece with it; and a laser beam branching mechanism disposed between the laser beam emitting means and the concentrator for branching the laser beam emitted from the laser beam emitting means into a plurality of laser beams. The laser beam branching mechanism has an angle adjustment means, and by adjusting the angle of entry of the P-polarized and S-polarized beams reflected by the first mirror and the second mirror into the second beam splitter using the angle adjustment means, the spacing between the focal points of the plurality of laser beams consisting of P-polarized and S-polarized beams focused by the concentrator is adjusted.

[0003] Japanese Patent Publication No. 2018-65174 describes a laser processing apparatus comprising a reflective spatial light modulator that modulates and emits laser light according to a phase pattern, a focusing lens unit that focuses the laser light toward a workpiece, and a slit member that blocks a portion of the laser light.

[0004] Japanese Patent Publication No. 2010-214431 describes a laser processing apparatus comprising: a light source; a diffractive optical element that receives light emitted from the light source and splits the incident light into multiple beams of light; a focusing lens that concentrates the light split by the diffractive optical element at multiple locations according to the branching angle; and an anamorphic optical means that applies a first action to the light incident on the diffractive optical element from the light source side to multiply it in at least one axial direction, and a second action to cancel out the first action to the light emitted from the diffractive optical element toward the focusing lens.

[0005] Laser grooving is a process that forms grooves on the surface of a workpiece, such as a semiconductor wafer, by irradiating it with a laser. In laser grooving, high-quality processing can be achieved by branching the beam output from the laser light source and forming multiple spots on the surface of the workpiece. The spacing between the multiple spots is preferably determined according to the energy of the irradiated beam, the laser repetition frequency, and the street width. Generally, for example, regarding energy, it is preferable to widen the spacing between spots as the beam energy is higher. However, existing laser dicing equipment is not configured to flexibly change the spacing between spots.

[0006] The disclosed technology was developed in view of the above-mentioned points, and aims to enable flexible changes in the spacing between multiple spots formed on the surface of a workpiece in a laser dicing apparatus.

[0007] A laser dicing apparatus according to the disclosed technology comprises a laser light source that outputs a beam, at least one lens provided on the optical path of the beam, a diffractive optical element provided in a convergence / divergence region, which is a region on the optical path where the beam converges or diverges due to the action of the lens, for branching the beam, and a moving mechanism for moving the diffractive optical element along the optical axis of the beam in the convergence / divergence region.

[0008] The laser dicing apparatus may have a relay lens including a first lens and a second lens, respectively, arranged on the optical path of the beam. The diffractive optical element may be provided between the first lens and the second lens. The moving mechanism may move the diffractive optical element along the optical axis of the beam in the region between the first lens and the second lens.

[0009] The laser dicing apparatus may have a filter provided between the first lens and the second lens that partially shields the beam. The diffractive optical element may be provided upstream of the filter in the direction of beam propagation. The moving mechanism may move the diffractive optical element along the optical axis of the beam in the region upstream of the filter in the direction of beam propagation.

[0010] The laser dicing apparatus may further include a rotation mechanism that rotates the diffractive optical element with the optical axis of the beam as the axis of rotation.

[0011] The laser dicing apparatus may include a relay lens including a first lens and a second lens, respectively, arranged on the optical path of the beam; a filter provided between the first lens and the second lens to partially shield the beam; and a plurality of diffractive optical elements that split the beam in directions different from each other. At least one of the plurality of diffractive optical elements may be provided in a first region between the laser light source and the first lens or in a second region between the first lens and the filter, and may split the beam in a direction intersecting the scanning direction of the beam with respect to the workpiece. At least one other of the plurality of diffractive optical elements may be provided in the second region or in a region downstream of the beam in the direction of beam propagation relative to the filter. The moving mechanism may move at least one of the plurality of diffractive optical elements along the optical axis of the beam in the convergence / divergence region.

[0012] The system may further include a rotation mechanism that rotates at least one of the plurality of diffractive optical elements with respect to the optical axis of the beam as the axis of rotation.

[0013] The moving mechanism may position the diffractive optical element based on a control command that specifies the spacing between a plurality of spots formed on the surface of a workpiece when the beam is irradiated onto the workpiece.

[0014] The moving mechanism may position the diffractive optical element based on a control command that specifies the size of a group of beam spots formed on the surface of a workpiece when the beam is irradiated onto the workpiece.

[0015] According to the disclosed technology, a laser dicing apparatus allows for flexible changes in the spacing between multiple spots formed on the surface of a workpiece.

[0016] This figure shows an example of the configuration of the optical system of a laser dicing apparatus according to an embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to an embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to an embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to an embodiment of the disclosed technology. This is an image of spots formed using the optical system according to an embodiment of the disclosed technology, captured by a camera placed at the focal point of the lens. This is a plan view showing an example of the arrangement of spots when forming a groove along a street. This is a plan view showing an example of the arrangement of spots when forming a groove along a street. This is a cross-sectional view along the line 4C-4C in Figures 4A and 4B. This figure shows an example of the arrangement of spots when forming a groove along a street. This is a cross-sectional view along the line 5B-5B in Figure 5A. This figure shows an example of the configuration of the optical system of a laser dicing apparatus according to another embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to another embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to another embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to another embodiment of the disclosed technology. This figure shows an example of the configuration of the optical system of a laser dicing apparatus according to another embodiment of the disclosed technology. This figure shows an example of the configuration of the optical system of a laser dicing apparatus according to another embodiment of the disclosed technology. This figure shows an example of the configuration of the optical system of a laser dicing apparatus according to another embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to another embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to another embodiment of the disclosed technology. This figure shows an example of multiple spots formed on a street according to another embodiment of the disclosed technology. This figure shows an example of multiple spots formed on a street according to another embodiment of the disclosed technology.This figure shows an example of the configuration of the optical system of a laser dicing apparatus according to another embodiment of the disclosed technology. This figure shows an example of the configuration of the optical system of a laser dicing apparatus according to another embodiment of the disclosed technology. This figure shows an example of the configuration of the optical system of a laser dicing apparatus according to another embodiment of the disclosed technology. This figure shows an example of the configuration of the control system of a laser dicing apparatus according to an embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to another embodiment of the disclosed technology. This figure shows an example of multiple spots formed on the surface of a workpiece by the optical system according to another embodiment of the disclosed technology. This figure shows an example of the configuration of the optical system of a laser dicing apparatus according to another embodiment of the disclosed technology.

[0017] Hereinafter, an example of an embodiment of the disclosed technology will be described with reference to the drawings. In each drawing, identical or equivalent components and parts will be given the same reference numerals, and redundant descriptions will be omitted.

[0018] [First Embodiment] Figure 1 shows an example of the configuration of an optical system 10 in a laser dicing apparatus according to an embodiment of the disclosed technology. The laser dicing apparatus is capable of laser grooving, which involves irradiating a workpiece 70 with a laser to form grooves on the surface of the workpiece 70. The workpiece 70 is, for example, a semiconductor wafer. In laser grooving, a pulsed laser is irradiated along streets that demarcate a plurality of devices provided on the semiconductor wafer, and by scanning, wiring layers including low-k films present on the streets are removed. The optical system 10 includes a laser light source 20, lenses 31, 32, 33, a diffractive optical element (DOE) 40, a moving mechanism 50, and a rotating mechanism 51.

[0019] The laser light source 20 is a laser oscillator that outputs a beam, for example, a UV pulsed laser. The beam output from the laser light source 20 is irradiated onto the surface of the workpiece 70 via lenses 31, 32, a diffractive optical element 40, and lens 33. In the following, the optical axis direction of the beam output from the laser light source 20 is defined as the Z direction, the scanning direction of the beam on the surface of the workpiece 70 is defined as the X direction, and the direction perpendicular to the Z direction and the X direction is defined as the Y direction.

[0020] Lenses 31 and 32 constitute a relay lens and function as a Kevlar-type beam expander. Lenses 31 and 32 are positioned so that their focal points coincide. Typically, lenses 31 and 32 have the same focal length, and the focal point is located midway between lens 31 and lens 32. The region between lens 31 and lens 32 is the convergence / divergence region R. ＣＤ The convergence / divergence region is a region in the optical path where the beam from the laser light source 20 converges or diverges due to the action of the lens.

[0021] The diffractive optical element 40 is an element that can spatially split laser light. In this embodiment, the diffractive optical element 40 splits the laser light so that multiple spots are aligned in a straight line on the surface of the workpiece 70. The diffractive optical element 40 is located between the lens 31 and lens 32 that constitute the relay lens, i.e., in the convergence / divergence region R. ＣＤ It will be placed there.

[0022] The rotation mechanism 51 rotates the diffractive optical element 40 around the optical axis of the beam from the laser light source 20. By rotating the diffractive optical element 40 around the optical axis of the beam, the orientation of the multiple spots that are formed in a straight line on the surface of the workpiece 70 is changed. The configuration of the rotation mechanism 51 is not particularly limited, but for example, it may include a movable roller that contacts the circumferential surface of the disc-shaped diffractive optical element 40.

[0023] The moving mechanism 50 is located in the convergence / divergence region R. ＣＤIn this configuration, the diffractive optical element 40 is moved along the optical axis of the beam. That is, the diffractive optical element 40 can be moved between lens 31 and lens 32 along the optical axis (Z direction) by the action of the movement mechanism 50. The diffractive optical element 40 is moved in the convergence / divergence region R ＣＤ By moving the beam along its optical axis, it becomes possible to change the spacing between multiple spots that are arranged in a straight line on the surface (XY plane) of the workpiece 70.

[0024] The moving mechanism 50 is located in the convergence / divergence region R. ＣＤ In the region between the focal point f and the lens 31, the diffractive optical element 40 may be moved along the optical axis of the beam. In this case, it is preferable to limit the range of movement so that the distance between the diffractive optical element 40 and the focal point f does not become excessively close. The reason for limiting the range of movement of the diffractive optical element 40 as described above is that if the diffractive optical element 40 reaches the focal point f where the energy density is high, the diffractive optical element 40 may be damaged. The moving mechanism 50 moves the rotation mechanism 51 together with the diffractive optical element 40. The configuration of the moving mechanism 50 is not particularly limited, but for example, it may include a linear motion mechanism using a linear guide and a ball screw.

[0025] Lens 33 is a focusing lens that focuses the beam that has passed through lens 31, diffractive optical element 40, and lens 32 onto the surface of the workpiece 70. The focal point of lens 33 is aligned with the surface of the workpiece 70, and a beam spot is formed on the surface of the workpiece 70. The workpiece 70 is held on a stage 71. The beam irradiated onto the surface of the workpiece 70 is scanned as the stage 71 moves in a plane that intersects with the optical axis of the beam.

[0026] Figures 2A, 2B, and 2C show examples of multiple spots S formed on the surface of a workpiece 70 by the optical system 10. Figure 2A illustrates six circular spots S arranged along the X direction on the surface of the workpiece 70. The six spots S are formed when a single beam output from the laser light source 20 is split into six beams by the diffractive optical element 40.

[0027] The diffractive optical element 40 moves to the convergence-divergence region R by the action of the movement mechanism 50. ＣＤ By moving the diffractive optical element 40 along the optical axis (Z direction) of the beam, the spacing between the multiple spots S changes. For example, when the diffractive optical element 40 moves within the region between the focal point f and the lens 31, if the diffractive optical element 40 is closer to the focal point f, the spacing between the multiple spots S becomes relatively shorter, as shown in Figure 2A, and if the diffractive optical element 40 is closer to the lens 31, the spacing between the multiple spots S becomes relatively longer, as shown in Figure 2B. By moving the diffractive optical element 40 from the lens 31 side to the focal point f side, the spacing between the multiple spots S can be continuously shortened, and by moving the diffractive optical element 40 from the focal point f side to the lens 31 side, the spacing between the multiple spots S can be continuously lengthened.

[0028] Furthermore, as the diffractive optical element 40 rotates around the optical axis of the beam as its axis of rotation, the arrangement direction of the multiple spots S formed on the surface of the workpiece 70 changes, as shown in Figure 2C.

[0029] Figure 3 shows an image of a spot formed using the optical system 10 according to this embodiment, captured by a camera placed at the focal point of the lens 33. The left side of Figure 3 shows the case where the diffractive optical element 40 is positioned in front of the focal point f and at a distance of 50 mm from the lens 31. The center side of Figure 3 shows the case where the diffractive optical element 40 is positioned in front of the focal point f and at a distance of 100 mm from the lens 31. The right side of Figure 3 shows the case where the diffractive optical element 40 is positioned in front of the focal point f and at a distance of 150 mm from the lens 31.

[0030] As described above, the laser dicing apparatus according to the disclosed technology comprises a laser light source 20 that outputs a beam, lenses 31 and 32 provided on the beam's optical path, and a convergence / divergence region R, which is a region on the optical path where the beam converges or diverges due to the action of the lenses 31 and 32. ＣＤ A diffractive optical element 40 is provided to split the beam, and a focusing / diverging region R is provided. ＣＤ The device includes a moving mechanism 50 that moves the diffractive optical element along the optical axis of the beam.

[0031] According to the laser dicing apparatus according to this embodiment, the moving mechanism 50 moves the diffractive optical element 40 along the optical axis of the beam in the converging / diverging region R, ＣＤ enabling flexible change of the interval between a plurality of spots S formed on the surface of the workpiece 70.

[0032] For example, in the laser grooving process of a semiconductor wafer, it is preferable to perform beam scanning while efficiently discharging debris generated by removing the wiring layer. By shortening the interval between a plurality of spots formed on the surface of the semiconductor wafer and arranging the plurality of spots without gaps, it is possible to increase the debris discharge efficiency as compared with the case where the plurality of spots are discretely present.

[0033] Also, in the laser grooving process, when trying to suppress heat damage to the semiconductor wafer, the energy per spot is limited to, for example, 10 μJ or less. In this case, if the interval between a plurality of spots formed on the surface of the semiconductor wafer is excessively long, the thermal interaction by the spots is not promoted and the processing efficiency decreases. In order to increase the processing efficiency, it may be preferable to shorten the interval between a plurality of spots to about 5 μm to 20 μm, for example.

[0034] Further, when forming a groove along a street, as shown in FIGS. 4A and 4B, a plurality of spots S having different positions in the width direction (Y direction) of the street 200 are formed. As shown in FIG. 4A, the direction in which the plurality of spots S are arranged may be orthogonal to the extending direction (X direction) of the street which is the processing target area. Alternatively, as shown in FIG. 4B, the direction in which the plurality of spots S are arranged may be inclined with respect to the extending direction (X direction) of the street which is the processing target area. If the interval between the plurality of spots S is excessively long, a plurality of streak-like portions 210 are formed by the wiring layer or the like that remains without being removed between two adjacent spots. FIG. 4C is a cross-sectional view taken along line 4C-4C in FIGS. 4A and 4B. Grooves 220 are formed at the irradiation positions of each spot, and streak-like portions 210 are formed between two adjacent grooves 220.

[0035] While the striated portion 210 can be removed by subsequent laser irradiation, if the width of the striated portion 210 is excessively wide, it becomes necessary to increase the laser energy or decrease the laser scanning speed in order to remove the striated portion 210. However, in this case, there is a risk of problems such as device damage due to heat or the generation of molten debris on the street.

[0036] As shown in Figure 5A, by shortening the spacing between multiple spots S formed on the street 200 in the width direction (Y direction) of the street 200, it is possible to suppress the occurrence of streaky areas. Figure 5B is a cross-sectional view along the line 5B-5B in Figure 5A.

[0037] On the other hand, when irradiating with a relatively high-energy laser, such as when processing metals or ceramics, if the distance between spots is excessively short, the spots may interfere with each other and weaken each other's energy. For this reason, it is preferable to increase the distance between adjacent spots to the extent that interference does not occur between them.

[0038] If you want to evenly distribute multiple spots across the width of the groove you intend to create (the width of the street), you need to determine the spacing between spots according to the groove width and the number of spots.

[0039] As described above, there is an optimal spot spacing from the viewpoint of ensuring processing quality and achieving the desired processing. One possible method for changing the spacing between multiple spots is to selectively arrange multiple types of diffractive optical elements on the optical path. However, in this case, the spot spacing can only be changed in steps (i.e., it lacks flexibility), and it may not be possible to set the optimal spot spacing. According to the laser dicing apparatus of the disclosed technology, the spacing between multiple spots formed on the surface of the workpiece can be continuously changed, making it possible to easily set the optimal spot spacing.

[0040] [Second Embodiment] Figure 6 shows an example of the configuration of an optical system 10A in a laser dicing apparatus according to a second embodiment of the disclosed technology. The optical system 10A has a filter 60 and two diffractive optical elements 40A and 40B whose beam branching directions are different from each other.

[0041] The filter 60 is positioned at the focal point of lenses 31 and 32, which constitute the relay lens. The filter 60 is a spatial filter that partially shields the beam. The filter 60 has an aperture, and when the beam passes through the aperture, ghosts (noise) generated when the beam passes through the diffractive optical elements 40A and 40B are removed. Here, ghosts refer to unwanted diffracted light.

[0042] The diffractive optical element 40A is located in the region R between the lens 31 and the filter 60. ２ It is located in region R. ２ This is the convergence / divergence region R. ＣＤ This is the region within. The rotation mechanism 51 rotates the diffractive optical element 40A with the optical axis of the beam from the laser light source 20 as the axis of rotation. The movement mechanism 50 is within region R ２ In this configuration, the diffractive optical element 40 is moved along the optical axis (Z direction) of the beam.

[0043] The diffractive optical element 40B is located in the region R between the laser light source 20 and the lens 31. １ It is located in region R. １ This is the convergence / divergence region R. ＣＤ This region is not included in the above. The diffractive optical element 40B is not provided with a rotation mechanism or a movement mechanism, and its position on the optical path is fixed. However, the diffractive optical element 40B may be provided with a rotation mechanism, and the diffractive optical element 40B may be configured to rotate with the optical axis as the axis of rotation.

[0044] Figures 7A, 7B, and 7C show examples of multiple spots S formed on the surface of the workpiece 70 by the optical system 10A, respectively. For example, the diffractive optical element 40A is in direction D Ａ The beam is split, and the diffractive optical element 40B is in direction D Ａ Direction D perpendicular to the direction. Ｂ The beam is split. For example, in direction DＢ This is the direction parallel to the X direction, which is the scanning direction of the beam, and direction D Ａ This direction is parallel to the Y direction, which is perpendicular to the beam scanning direction.

[0045] As the rotation mechanism 51 causes the diffractive optical element 40A to rotate around the optical axis of the beam as the axis of rotation, the multiple spots S are arranged in the direction D, as shown in Figure 7B. Ａ From direction D Ａ It changes to ' and is arranged in a state tilted with respect to the Y direction. In addition, the diffractive optical elements 40A move along the optical axis in region R by the action of the moving mechanism 50. ２ By moving inside, as shown in Figure 7C, the direction D of multiple spots S Ａ The spacing in ' changes.

[0046] Variations of the optical system having two diffractive optical elements 40A and 40B are shown below. In the optical system 10B shown in Figure 8, the diffractive optical element 40A is located in the region R between the lens 31 and the filter 60. ２ The diffractive optical element 40B is positioned in the region R between lens 32 and lens 33. ４ It is located in region R. ４ This is the convergence / divergence region R. ＣＤ This region is not included in the region R. The diffractive optical element 40A is provided with a rotation mechanism 51 and a movement mechanism 50. The diffractive optical element 40A can be rotated around the optical axis of the beam by the action of the rotation mechanism 51, and the region R can be rotated by the action of the movement mechanism 52. ２ The beam can move along its optical axis within the optical system. With optical system 10B, it is possible to form a spot on the surface of the workpiece 70 in a manner similar to that of optical system 10A shown in Figure 6 (see Figures 7A, 7B, and 7C).

[0047] In the optical system 10C shown in Figure 9, the diffractive optical elements 40A and 40B are located in the region R between the lens 31 and the filter 60, respectively. ２ It is located in region R. ２ This is the convergence / divergence region R. ＣＤThis is the region within R. The diffractive optical elements 40A and 40B are provided with a rotation mechanism 51A and 51B and a moving mechanism 50A and 50B, respectively. The diffractive optical elements 40A and 40B can be rotated around the optical axis of the beam by the action of the rotation mechanism 51A and 51B, respectively, and the region R can be rotated by the action of the moving mechanism 50A and 50B. ２ It can move inside along the optical axis of the beam.

[0048] In the optical system 10D shown in Figure 10, the diffractive optical element 40A is located in the region R between the lens 31 and the filter 60. ２ It is positioned in the region R between the filter 60 and the lens 32. ３ It is located in region R. ２ and region R ３ These are the convergence and divergence regions R, respectively. ＣＤ This is the region within R. The diffractive optical elements 40A and 40B are provided with a rotation mechanism 51A and 51B and a moving mechanism 50A and 50B, respectively. The diffractive optical element 40A can be rotated around the optical axis of the beam by the action of the rotation mechanism 51A, and the region R can be rotated by the action of the moving mechanism 50A. ２ It is movable within the beam along its optical axis. The diffractive optical element 40B can rotate around the optical axis of the beam by the action of the rotation mechanism 51B, and the movement mechanism 50B can move it within region R ３ It can move inside along the optical axis of the beam.

[0049] Figure 11 shows an example of how the spacing between multiple spots S formed by optical systems 10C and 10D changes. For example, the diffractive optical element 40A is in direction D Ａ The beam is split, and the diffractive optical element 40B is in direction D Ａ Direction D perpendicular to the direction. Ｂ The beam is split in direction D. Ｂ For example, direction D is parallel to the X direction, which is the beam scanning direction. Ａ This direction is parallel to the Y direction, which is perpendicular to the beam scanning direction.

[0050] The diffractive optical element 40A moves along the optical axis in region R by the action of the movement mechanism 50A. ２By moving inside, the direction D of multiple spots S Ａ The spacing in the (Y direction) changes. Figures 11(a) and 11(b) show the direction D of multiple spots S. Ａ This shows the change in spacing in the (Y direction).

[0051] The diffractive optical element 40B moves along the optical axis in region R by the action of the movement mechanism 50B. ２ or region R ３ By moving inside, the direction D of multiple spots S Ｂ The spacing in the (X direction) changes. Figures 11(b) and 11(c) show the direction D of multiple spots S. Ａ This shows the change in spacing in the (X direction).

[0052] When at least one of the diffractive optical elements 40A and 40B rotates around the optical axis of the beam, the orientation of the arrangement of the multiple spots S changes. Figure 12 shows an example of how the spacing between the multiple spots S changes when the diffractive optical element 40A is rotated in optical systems 10C and 10D. Figure 12 shows that the orientation of the arrangement of the multiple spots S changes in direction D due to the rotation of the diffractive optical element 40A. Ａ An example is given where it is written as '.

[0053] According to the optical system 10C, both the diffractive optical elements 40A and 40B are in region R ２ Because they are positioned in such a way, the filter 60 can remove ghosts generated when the beam passes through the diffractive optical elements 40A and 40B.

[0054] On the other hand, in the optical system 10D, the diffractive optical element 40A is in region R ２ The diffractive optical element 40B is positioned in region R ３In optical system 10D, since there is only one diffractive optical element positioned within each of the positioning regions of the diffractive optical elements 40A and 40B, the movement range of the diffractive optical elements 40A and 40B can be widened compared to optical system 10C. This allows for a wider adjustment range of the spot spacing. On the other hand, in optical system 10D, since the diffractive optical element 40B is located downstream of the filter 60 in the direction of beam propagation, a problem arises in that the ghost generated when the beam passes through the diffractive optical element 40B cannot be removed by the filter 60.

[0055] Here, Figures 13A and 13B show examples of multiple spots S formed on a street 200 of a semiconductor wafer when using the optical system 10D. Figure 13A shows a diffractive optical element 40A provided upstream of the filter 60 in direction D Ａ The beam is split, and the diffractive optical element 40B located downstream of the filter 60 is directed in direction D Ａ Direction D perpendicular to the direction. Ｂ This shows the case where the beam is split. Figure 13B shows the diffractive optical element 40A provided upstream of the filter 60 in direction D Ｂ The beam is split, and the diffractive optical element 40B located downstream of the filter 60 is directed in direction D Ａ This shows the case where the beam is split. Direction D Ｂ This is a direction parallel to the X direction, which is the beam scanning direction (the direction in which Street 200 extends), and direction D Ａ This direction is parallel to the Y direction, which is perpendicular to the beam scanning direction (the width direction of the street).

[0056] The diffractive optical element 40A is in direction D Ａ The beam is split in a direction perpendicular to the beam scanning direction, and the diffractive optical element 40B is in direction D Ｂ When the beam is split in a direction parallel to the beam scanning direction, the direction D is caused by the diffractive optical element 40A. Ａ Ghosts generated in this arrangement are removed by the filter 60. On the other hand, ghosts in direction D are caused by the diffractive optical element 40B. ＢThe ghosts generated in this sequence are not removed, and as shown in Figure 13A, a group of spots G due to the ghosts is formed on the surface of the semiconductor wafer. In this case, the group of spots G due to the ghosts is formed inside the street 200, i.e., within the processing area, so there is no problem with the processing quality.

[0057] On the other hand, the diffractive optical element 40A is in direction D Ｂ The beam is split in a direction parallel to the beam scanning direction, and the diffractive optical element 40B is in direction D Ａ When the beam is split in a direction perpendicular to the beam scanning direction, the direction D is caused by the diffractive optical element 40A. Ｂ Ghosts generated in this arrangement are removed by the filter 60. On the other hand, ghosts in direction D are caused by the diffractive optical element 40A. Ａ The ghosts that occur in this sequence are not removed, and as shown in Figure 13B, a group of spots G due to the ghosts is formed on the surface of the semiconductor wafer. In this case, the group of spots G due to the ghosts is formed outside the street 200, i.e., outside the processing area, so there is a risk that problems will occur in processing quality.

[0058] Therefore, in the optical system 10D, the diffractive optical element 40A, which is positioned upstream of the filter 60 in the direction of beam propagation, is in direction D Ａ The beam is split in a direction perpendicular to the beam scanning direction, and the diffractive optical element 40B, which is positioned downstream of the beam propagation direction relative to the filter 60, is in direction D Ｂ It is preferable that the beam is split in a direction parallel to the beam scanning direction. However, the beam splitting direction by the diffractive optical element 40B does not have to be parallel to the beam scanning direction, as long as it is within the range of the area to be processed.

[0059] The optical system of the laser dicing apparatus may have the following configuration. In the optical system 10E shown in Figure 14, the diffractive optical elements 40A and 40B are located in the region R between the filter 60 and the lens 32, respectively. ３ It is located in region R. ３ This is the convergence / divergence region R. ＣＤThis is the region within R. The diffractive optical elements 40A and 40B are each provided with a rotation mechanism 51A and 51B and a moving mechanism 50A and 50B, respectively. The diffractive optical elements 40A and 40B can be rotated around the optical axis of the beam by the action of the rotation mechanism 51A and 51B, respectively, and the region R can be rotated by the action of the moving mechanism 50A and 50B. ３ It can move inside along the optical axis of the beam.

[0060] The optical system 10F shown in Figure 15 has two sets of relay lenses. The first relay lens includes lenses 31, 32 and filter 60A. The second relay lens includes lenses 34, 35 and filter 60B. The region between lenses 31 and 32 that constitute the first relay lens is the first convergence / divergence region R. ＣＤ１ Therefore, the region between lens 34 and lens 35 that constitute the second relay lens is the second convergence / divergence region R. ＣＤ２ The diffractive optical element 40A is in the first convergence / divergence region R. ＣＤ１ The diffractive optical element 40B is provided in the second convergence / divergence region R ＣＤ２ It is located at [location].

[0061] The diffractive optical elements 40A and 40B are provided with a rotation mechanism 51A and 51B and a moving mechanism 50A and 50B, respectively. The diffractive optical element 40A can be rotated around the optical axis of the beam by the action of the rotation mechanism 51A, and the first convergence / divergence region R can be formed by the action of the moving mechanism 50A. ＣＤ１ The diffractive optical element 40B is movable along the optical axis of the beam within (more specifically, the region between lens 31 and filter 60A). The diffractive optical element 40B is rotatable around the optical axis of the beam by the action of the rotation mechanism 51B, and the second convergence / divergence region R is formed by the action of the movement mechanism 50B. ＣＤ２ The interior (more specifically, the region between lens 34 and filter 60B) is movable along the optical axis of the beam. The optical system 10F makes it possible to eliminate ghosting caused by diffractive optical elements 40A and 40B while ensuring the movement range of both diffractive optical elements 40A and 40B.

[0062] In the optical system 10G shown in Figure 16, the diffractive optical element 40A is in the first convergence / divergence region R ＣＤ１It is arranged in the region between the lens 31 and the filter 60 which is the inner region. The diffractive optical element 40B is in the second converging / diverging region R ＣＤ２ It is arranged in the region between the lens 33 and the workpiece 70 which is the inner region. The diffractive optical elements 40A and 40B are respectively provided with rotation mechanisms 51A and 51B and movement mechanisms 50A and 50B. The diffractive optical element 40A can rotate about the optical axis of the beam as the rotation axis by the action of the rotation mechanism 51A, and can move along the optical axis of the beam within the first converging / diverging region R ＣＤ１ Inside (more specifically, the region between the lens 31 and the filter 60). The diffractive optical element 40B can rotate about the optical axis of the beam as the rotation axis by the action of the rotation mechanism 51B, and can move along the optical axis of the beam within the second converging / diverging region R ＣＤ２ In the optical system 10G, the diffractive optical element 40A arranged upstream of the filter 60A in the traveling direction of the beam branches the beam in the direction D Ａ (The direction perpendicular to the scanning direction of the beam), and it is preferable that the diffractive optical element 40B arranged downstream of the filter 60A in the traveling direction of the beam branches the beam in the direction D Ｂ (The direction parallel to the scanning direction of the beam). Thereby, as shown in FIG.  13A, the spot group G due to ghost is formed inside the street 200, that is, inside the processing target region, so that it is possible to prevent problems from occurring in the processing quality. Note that the beam branching direction by the diffractive optical element 40B does not have to be parallel to the scanning direction of the beam as long as it is within the range that fits within the processing target region.

[0063] FIG. 17 is a diagram showing an example of the configuration of the control system of the laser dicing apparatus according to the embodiment of the disclosed technology. The laser dicing apparatus has a control unit 80 that controls the movement mechanisms 50A and 50B. The control unit 80 is constituted by, for example, a microcomputer, and supplies a control command C Ｃ to each of the movement mechanism 50A provided in the diffractive optical element 40A and the movement mechanism 50B provided in the diffractive optical element 40B. The movement mechanism 50A is supplied with the control command C ＣBased on this, the positioning of the diffractive optical element 40A is performed, and the moving mechanism 50B positions the diffractive optical element 40B based on the control command C. Ｃ Based on this, the positioning of the diffractive optical element 40B is performed.

[0064] The control command C Ｃ may specify the interval P between a plurality of beam spots S formed on the surface of the object to be processed 70. As shown in FIG. 18A, the interval P Ａ , P Ｂ is the spot interval in the direction D. As shown in FIG. 18A, the interval P Ａ is the spot interval in the direction D. Ａ is the spot interval in the direction D. Ｂ is the spot interval in the direction D. Ｂ is the spot interval in the direction D.

[0065] The moving mechanism 50A provided in the diffractive optical element 40A that branches the beam in the direction D positions the diffractive optical element 40A such that the interval in the direction D of the plurality of spots S is the interval P Ａ specified by the control command C. The moving mechanism 50B provided in the diffractive optical element 40B that branches the beam in the direction D positions the diffractive optical element 40B such that the interval in the direction D of the plurality of spots S is the interval P Ａ specified by the control command C. Ｃ specified by the control command C. Ａ specified by the control command C. Ｂ specified by the control command C. Ｂ specified by the control command C. Ｃ specified by the control command C. Ｂ specified by the control command C. <00002​​​​​​​​​​​​​​​​​​​​​​​Size L as specified by Ａ The diffractive optical element 40A is positioned in such a manner. Direction D Ｂ The moving mechanism 50B provided on the diffractive optical element 40B that splits the beam is in the direction D of the spot group. Ｂ The total length in control command C Ｃ Size L as specified by Ｂ The diffractive optical element 40B is positioned accordingly.

[0068] In the above description, an optical system including two diffractive optical elements 40A and 40B has been illustrated, but the optical system may include three or more diffractive optical elements. In this case, it is preferable that the optical system satisfies all of the following conditions (1) to (4) in the configuration shown in Figure 19. (1) At least one of the plurality of diffractive optical elements is located in the region R between the laser light source 20 and the lens 31. １ Or the region R between lens 31 and filter 60 ２ It is provided in such a way that the beam is split in a direction that intersects with the scanning direction of the beam with respect to the workpiece 70. (2) At least one of the plurality of diffractive optical elements is in region R ２ Or the third region R between the filter 60 and the lens 32 ３ (3) Of the plurality of diffractive optical elements, at least one diffractive optical element located downstream of the beam in the direction of beam propagation relative to the filter 60 splits the beam in a direction parallel to the scanning direction of the beam with respect to the workpiece 70. (4) The moving mechanism moves at least one of the plurality of diffractive optical elements to the convergence / divergence region R ＣＤ The beam is moved along its optical axis.

[0069] In some of the optical systems illustrated above, the diffractive optical element 40B, which is positioned downstream of the filter 60 in the direction of beam propagation, is in direction D Ｂ The beam was split in a direction parallel to the beam scanning direction, but the optical system is not limited to the example shown. That is, in an optical system where the diffractive optical element 40B is positioned downstream of the beam in the direction of beam propagation relative to the filter, the optical element is in direction D ＢIt is possible to prevent problems with processing quality by splitting the beam (in a direction parallel to the beam scanning direction). However, the beam splitting direction by the diffractive optical element 40B does not have to be parallel to the beam scanning direction, as long as it is within the processing area.

[0070] The filter exemplified above has an aperture, but is not limited to this. For example, a filter with a slit may also be used. Of the beam branched by the diffractive optical element, the necessary portion passes through the slit, and the unnecessary portion is removed by the slit. The filter may be constructed by arranging two plates, each having a straight section, so that the gap between the straight sections forms a slit. Furthermore, a mechanism for changing the distance between the two plates may be provided, and the distance between the two plates may be changed by control. A filter with a slit is easier to design than a filter with an aperture.

[0071] Each of the optical systems exemplified above may include a beam shaper for shaping the spot to a desired shape, a beam expander for adjusting the spot diameter to an appropriate size, and an attenuator for adjusting the laser output.

[0072] Furthermore, the disclosures of Japanese Patent Application No. 2025-020308, filed on 10 February 2025, and Japanese Patent Application No. 2025-204045, filed on 26 November 2025, are incorporated herein by reference in their entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if the incorporation of each individual document, patent application, and technical standard were specifically and individually noted.

Claims

1. A laser dicing apparatus comprising: a laser light source that outputs a beam; at least one lens provided on the optical path of the beam; a diffractive optical element provided in a convergence / divergence region, which is a region on the optical path where the beam converges or diverges due to the action of the lens, for branching the beam; and a moving mechanism for moving the diffractive optical element along the optical axis of the beam in the convergence / divergence region.

2. A laser dicing apparatus according to claim 1, comprising a relay lens including a first lens and a second lens respectively arranged on the optical path of the beam, wherein the diffractive optical element is provided between the first lens and the second lens, and the moving mechanism moves the diffractive optical element along the optical axis of the beam in the region between the first lens and the second lens.

3. A laser dicing apparatus according to claim 2, comprising a filter provided between the first lens and the second lens for partially shielding the beam, wherein the diffractive optical element is provided upstream of the filter in the direction of beam propagation, and the moving mechanism moves the diffractive optical element along the optical axis of the beam in a region upstream of the filter in the direction of beam propagation.

4. The laser dicing apparatus according to claim 1, further comprising a rotation mechanism for rotating the diffractive optical element with the optical axis of the beam as the axis of rotation.

5. A laser dicing apparatus according to claim 1, comprising: a relay lens including a first lens and a second lens respectively arranged on the optical path of the beam; a filter provided between the first lens and the second lens for partially shielding the beam; and a plurality of diffractive optical elements having different directions for branching the beam, wherein at least one of the plurality of diffractive optical elements is provided in a first region between the laser light source and the first lens or in a second region between the first lens and the filter, and branches the beam in a direction intersecting the scanning direction of the beam with respect to the workpiece; at least one other of the plurality of diffractive optical elements is provided in the second region or in a region downstream of the beam in the direction of travel of the beam relative to the filter; and the moving mechanism moves at least one of the plurality of diffractive optical elements along the optical axis of the beam in the convergence / divergence region.

6. The laser dicing apparatus according to claim 5, further comprising a rotation mechanism for rotating at least one of the plurality of diffractive optical elements with respect to the optical axis of the beam as the axis of rotation.

7. The laser dicing apparatus according to claim 1, wherein the moving mechanism positions the diffractive optical element based on a control command that specifies the spacing between a plurality of spots formed on the surface of a workpiece when the beam is irradiated onto the workpiece.

8. The laser dicing apparatus according to claim 1, wherein the moving mechanism positions the diffractive optical element based on a control command that specifies the size of a group of spots consisting of a plurality of beam spots formed on the surface of a workpiece when the beam is irradiated onto the workpiece.

9. The laser dicing apparatus according to claim 1, wherein the direction in which a plurality of spots formed on the surface of a workpiece by irradiating the workpiece with the beam is aligned is perpendicular to the direction in which the workpiece region extends.

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