Laser beam irradiation device, laser beam irradiation method, and chip manufacturing method

Abstract

This enables stable processing of objects using laser beams. [Solution] A laser beam irradiation device for irradiating an object to be processed (1) with a laser beam (L), comprising: a holding part (12) for holding the object to be processed; a laser light source (21) for outputting a laser beam; a mask (26) for blocking a portion of the laser beam output from the laser light source and allowing a portion to pass through; a focusing lens (24) for focusing the laser beam that has passed through the mask; and a heat diffusion suppression member (30) disposed on the upper part of the mask, which transmits the laser beam and suppresses the diffusion of heat generated when the laser beam is irradiated onto the mask.

Description

Technical Field

[0001] The present invention relates to a laser beam irradiation device for irradiating a processing object with a laser beam, a laser beam irradiation method, or a method for manufacturing a chip by irradiating a laser beam.

Background Art

[0002] As disclosed in Patent Document 1 and Patent Document 2, when irradiating a processing object with a laser beam, a method of passing through a mask having a slit is known as a method of adjusting the beam shape.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a mask is disposed on the optical path for irradiating a processing object with a laser beam, the portion of the mask irradiated with the laser beam generates heat, and fluctuations occur in the air in the optical path through which the laser beam passes due to the heat generation, affecting the laser beam and causing a problem that the processing becomes unstable.

[0005] In view of such problems, an object of the present invention is to realize stable processing of a processing object by a laser beam.

Means for Solving the Problems

[0006] One aspect of the present invention is a laser beam irradiation device for irradiating an object to be processed with a laser beam, comprising: a holding unit for holding the object to be processed; a laser light source for emitting the laser beam; a mask for blocking a portion of the laser beam emitted from the laser light source and allowing a portion to pass through; a focusing lens for focusing the laser beam that has passed through the mask; and a heat diffusion suppression member disposed above the mask, which transmits the laser beam and suppresses the diffusion of heat generated when the laser beam is irradiated onto the mask.

[0007] The heat diffusion suppressing member is arranged to accommodate the cross-section of the laser beam, and it is preferable that at least the region through which the beam passes is made of a material that is transparent to the laser beam.

[0008] The distance between the mask and the heat diffusion suppression member in the optical axis direction of the laser beam is preferably 0.1 mm or more and 5 mm or less.

[0009] The thickness of the heat diffusion suppressing member in the optical axis direction of the laser beam is preferably 0.1 mm or more and 1 mm or less.

[0010] One aspect of the present invention is a laser beam irradiation method for irradiating an object to be processed with a laser beam, comprising: a holding step of holding the object to be processed with a holding unit; and an irradiation step of irradiating the object to be processed with a laser beam output from a laser light source via an optical system, wherein the optical system comprises: a mask that blocks a portion of the laser beam output from the laser light source and allows a portion to pass through; a focusing lens that focuses the laser beam that has passed through the mask; and a heat diffusion suppression member disposed above the mask, which transmits the laser beam and suppresses the diffusion of heat generated when the laser beam is irradiated onto the mask.

[0011] One aspect of the present invention is a method for manufacturing chips, which involves irradiating a workpiece with a laser beam to divide it into a plurality of chips, comprising: a holding step of holding the workpiece with a holding part; and a dividing step of irradiating the workpiece with a laser beam output from a laser light source through an optical system to form laser processing marks, and dividing the workpiece into a plurality of chips starting from the laser processing marks, or dividing the workpiece into a plurality of chips by the laser processing marks, wherein the optical system comprises: a mask that blocks a portion of the laser beam output from the laser light source and allows a portion to pass through; a focusing lens that focuses the laser beam that has passed through the mask; and a heat diffusion suppression member disposed above the mask, which transmits the laser beam and suppresses the diffusion of heat generated when the laser beam is irradiated onto the mask. [Effects of the Invention]

[0012] According to each of the above embodiments, by suppressing the diffusion of heat generated when a laser beam is irradiated onto the mask using a heat diffusion suppression member, stable processing of the object to be processed by the laser beam can be achieved. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view of a laser beam irradiation device. [Figure 2] This is a cross-sectional view showing the state in which a laser beam is irradiated onto the object to be processed. [Figure 3] This is a perspective view showing the state of irradiating an object to be processed with a laser beam. [Figure 4] This is a table showing the results of the first experiment. [Figure 5] This is a table showing the results of the second experiment. [Figure 6] This figure shows a modified example of a heat diffusion suppression member. [Figure 7] This figure shows a modified example of a heat diffusion suppression member. [Figure 8] This figure shows an example of the process performed in the irradiation step. [Figure 9] This figure shows an example of the process performed in the irradiation step. [Figure 10]It is a cross-sectional view showing different arrangements of the optical system of the laser irradiation unit.

Embodiment for Carrying Out the Invention

[0014] Hereinafter, with reference to the accompanying drawings, the laser beam irradiation device, the laser beam irradiation method, and the method for manufacturing a chip of the present disclosure will be described. FIG. 1 shows a laser beam irradiation device 10 which is an example of the laser beam irradiation device of the present disclosure. The X-axis direction, Y-axis direction, and Z-axis direction shown in each drawing are perpendicular to each other, and the X-axis direction and the Y-axis direction are the horizontal directions in the laser beam irradiation device 10. The Z-axis direction is the vertical direction in the laser beam irradiation device 10, the +Z direction is upward, and the -Z direction is downward. The -Z direction can also be expressed as the vertical direction in which gravity acts.

[0015] The laser beam irradiation device 10 irradiates a processing object 1 with a laser beam L (see FIGS. 2 and 3) to process (machining) the processing object 1. The processing object 1 may be referred to as a workpiece, a work, etc. Details of the processing performed on the processing object 1 using the laser beam irradiation device 10 will be described later. In the present embodiment, the laser beam irradiation device 10 performs processing for dividing the processing object 1 to manufacture a plurality of chips 3 (see FIG. 3).

[0016] As shown in FIG. 3, the processing object 1 has a plurality of device regions separated by grid-like streets 2, and chips 3 are formed in each device region. A division planned line 4 serving as a reference for dividing each chip 3 is set on the street 2. In FIG. 3, only the division planned line 4 in some of the streets 2 is shown. As an example, the processing object 1 is a disk-shaped semiconductor wafer, and the chip 3 is a semiconductor device, but the shape of the processing object 1 and the type of the chip 3 are not limited. For example, the processing object 1 may be a rectangular package substrate or the like. The processing object 1 is attached inside a ring-shaped frame 6 via a flexible tape 5, and a processing object unit 7 composed of the processing object 1, the tape 5, and the frame 6 is configured.

[0017] As shown in FIG. 1, a holding table 12, which is a holding part for holding the object to be processed 1, is provided on the base 11 of the laser beam irradiation apparatus 10. As shown in FIG. 2, the holding table 12 has a holding surface 13 formed of a porous plate made of a porous material on its upper surface, and the suction force of the suction source 14 can act on the holding surface 13. The object to be processed unit 7 conveyed to the laser beam irradiation apparatus 10 has the object to be processed 1 held on the holding surface 13 via the tape 5. Four clamp parts 15 are provided at equal intervals in the circumferential direction on the outer peripheral part of the holding table 12, and the frame 6 of the object to be processed unit 7 is held by the clamp parts 15.

[0018] The holding table 12 is moved in the X-axis direction by an X-axis moving mechanism 16. The X-axis moving mechanism 16 includes a pair of X-axis guide rails 161 extending in the X-axis direction on the base 11, an X-axis moving block 162 supported by the X-axis guide rails 161 so as to be movable in the X-axis direction, an X-axis ball screw 163 extending in the X-axis direction and screwed into the nut part of the X-axis moving block 162, and a motor 164 for rotating the X-axis ball screw 163. When the X-axis ball screw 163 is rotated by the motor 164, the X-axis moving block 162 moves in the X-axis direction along the X-axis guide rails 161.

[0019] The holding table 12 is supported on the X-axis moving block 162 via a table rotation mechanism 17. The table rotation mechanism 17 can rotate the holding table 12 about an axis in the Z-axis direction by a motor (not shown).

[0020] The laser beam irradiation apparatus 10 includes a laser irradiation unit 20 disposed above the holding table 12. The laser irradiation unit 2​​​The Y-axis movement mechanism 18 includes a pair of Y-axis guide rails 181 extending in the Y-axis direction on the base 11, a Y-axis movement block 182 supported by the Y-axis guide rails 181 so as to be movable in the Y-axis direction, a Y-axis ball screw 183 extending in the Y-axis direction and screwed into a nut portion of the Y-axis movement block 182, and a motor 184 for rotating the Y-axis ball screw 183. When the motor 184 rotates the Y-axis ball screw 183, the Y-axis movement block 182 moves in the Y-axis direction along the Y-axis guide rails 181.

[0022] The Z-axis movement mechanism 19 includes a pair of Z-axis guide rails 191 attached to the side of the Y-axis movement block 182 and extending in the Z-axis direction, a Z-axis movement block 192 supported by the Z-axis guide rails 191 so as to be movable in the Z-axis direction, a Z-axis ball screw 193 extending in the Z-axis direction and screwed into a nut portion of the Z-axis movement block 192, and a motor 194 for rotating the Z-axis ball screw 193. When the motor 194 rotates the Z-axis ball screw 193, the Z-axis movement block 192 moves in the Z-axis direction along the Z-axis guide rails 191.

[0023] The configuration in which the holding table 12 and the laser irradiation unit 20 move relative to each other is not limited to that of this embodiment. For example, either the holding table 12 or the laser irradiation unit 20 may be supported so as to be movable in both the X-axis and Y-axis directions, while the other of the holding table 12 or the laser irradiation unit 20 is configured not to move horizontally. Alternatively, the laser irradiation unit 20 may not move in the Z-axis direction, and instead the holding table 12 may move in the Z-axis direction.

[0024] A protrusion 40 is provided that extends from the Z-axis movement block 192 toward the -Y direction, and a laser irradiation unit 20 is positioned on the protrusion 40. By operating the X-axis movement mechanism 16 and the Y-axis movement mechanism 18, the processing object unit 7 held on the holding table 12 and the laser irradiation unit 20 can be moved relative to each other in the X-axis and Y-axis directions, thereby changing the irradiation position of the laser beam L from the laser irradiation unit 20 to the processing object 1 in the horizontal direction.

[0025] The protruding portion 40 is provided with an imaging unit 41 capable of imaging downwards, located near the laser irradiation unit 20. The imaging unit 41 can image the object to be processed 1 held on the holding table 12, and the laser irradiation unit 20 can be aligned with respect to the object to be processed 1 based on the image captured.

[0026] As shown in Figure 2, the optical system of the laser irradiation unit 20 includes a laser light source 21 that emits a laser beam L, which is a pulsed laser with a wavelength absorbed by the object to be processed 1; an output adjustment unit 22 that adjusts the laser beam L emitted by the laser light source 21 to a predetermined output; a mirror 23 that reflects the laser beam L whose output has been adjusted by the output adjustment unit 22; and a focusing lens 24 that focuses the laser beam L. The laser light source 21 may also be called a laser oscillator or the like.

[0027] The laser light source 21 and the output adjustment unit 22 are located inside the protruding portion 40, and a horizontal optical path Pa is formed in which the laser beam L propagates roughly horizontally (Y-axis direction) from the laser light source 21 toward the mirror 23. The mirror 23 reflects the laser beam L propagating along the horizontal optical path Pa downward (-Z direction), forming a vertical optical path Pb in which the laser beam L propagates downward toward the focusing lens 24 from the mirror 23. The vertical optical path Pb is located inside the processing head 25 provided at the -Y-direction end of the protruding portion 40. The optical axis Q extending in the Z-axis direction is a virtual axis passing through the center of the vertical optical path Pb and coincides with the optical axis of the focusing lens 24. In the vertical optical path Pb, the laser beam L propagates as a beam along the optical axis Q. The range of the laser beam L perpendicular to the optical axis Q is defined as the beam cross section Lv (see Figure 3). The optical axis direction refers to the direction along the optical axis Q, and in the portion of the vertical optical path Pb, it is synonymous with the Z axis direction. The optical axis direction may also be called the laser irradiation direction.

[0028] The optical system of the laser irradiation unit 20 is not limited to the configuration of this embodiment. For example, the optical system may be configured such that the laser beam L travels in a straight line in the Z-axis direction from the laser light source 21 positioned above to the focusing lens 24 positioned below, without reflection of the laser beam L by the mirror 23 (without the mirror 23). Alternatively, the optical system may be configured to include multiple mirrors or prisms so that the laser beam L is reflected or bent multiple times.

[0029] The operation of the Z-axis movement mechanism 19 moves the laser irradiation unit 20 in the Z-axis direction, thereby changing the position of the focal point of the laser beam L focused by the focusing lens 24 in the Z-axis direction. This makes it possible to change the focal point of the laser beam L emitted from the laser irradiation unit 20 in the thickness direction of the object to be processed 1 on the holding table 12.

[0030] The laser irradiation unit 20 is equipped with a mask 26. The mask 26 is positioned on the vertical optical path Pb between the mirror 23 and the focusing lens 24. That is, the mask 26 is positioned below the mirror 23 (-Z direction side) and above the focusing lens 24 (+Z direction side). As shown in Figure 3, the mask 26 is a plate-shaped or sheet-shaped member having a predetermined thickness in the Z-axis direction, and has a slit 27 penetrating in the thickness direction and a shielding portion 28 around the slit 27. The mask 26 allows the laser beam L to pass through at the location of the slit 27, while the shielding portion 28 blocks the laser beam L from passing through. The mask 26, positioned to cross the vertical optical path Pb, blocks a portion of the laser beam L output from the laser light source 21 with the shielding portion 28 and allows a portion of the laser beam L to pass through the slit 27. By using such a mask 26, the beam shape of the laser beam L traveling from the mirror 23 toward the focusing lens 24 can be changed.

[0031] The mask 26 shown in Figure 3 has one rectangular slit 27, but the configuration of the mask 26 is not limited to this. For example, the mask 26 may have a slit of a shape other than rectangular, or it may have multiple slits. Also, although the outer shape of the mask 26 shown in Figure 3 is rectangular, the outer shape of the mask 26 is not limited to a rectangle, and may be circular or other shapes.

[0032] When the laser beam L is at high power, the area of ​​the shielding portion 28 of the mask 26 that is irradiated with the laser beam L (the area where the laser beam L is blocked by the shielding portion 28) heats up, and the surrounding air is heated as a result of the heat, causing fluctuations in the air. When fluctuations occur in the air along the optical path through which the laser beam L passes, it affects the propagation of the laser beam L, and as a result, the processing (machining) of the object to be processed 1, which is irradiated with the laser beam L, may become unstable. In particular, the vertical optical path Pb in which the mask 26 is located is a vertical optical path in which the laser beam L propagates from top to bottom, and the high temperature air heated by the heated mask 26 (shown as high temperature air K in Figure 2) generates an updraft, causing the high temperature air K to rise along the vertical optical path Pb towards the mirror 23. Therefore, the heat generated by the mask 26 makes the air in the vertical optical path Pb prone to fluctuations, which is highly likely to have a negative impact on the processing performance (machining accuracy) of the laser irradiation unit 20.

[0033] It is known that cooling devices are used to prevent the mask irradiated with a laser beam from becoming overheated. However, existing cooling devices have had difficulty adequately addressing the problem of preventing the surrounding air from warming up and affecting the stability of the laser beam. In addition, introducing cooling devices is costly. Furthermore, structural constraints may prevent the installation of large-scale cooling devices in some cases.

[0034] To resolve these problems, the laser beam irradiation device 10 of this embodiment is equipped with a heat diffusion suppression member 30 in the optical system of the laser irradiation unit 20. The heat diffusion suppression member 30 is mounted inside the processing head 25. The heat diffusion suppression member 30 is positioned on the vertical optical path Pb between the mirror 23 and the focusing lens 24, and is particularly positioned above the mask 26. The heat diffusion suppression member 30 is made of a material that is transparent to the laser beam L (for example, quartz glass). The upper surface of the heat diffusion suppression member 30 is the incident surface 31 into which the laser beam L traveling from the mirror 23 toward the mask 26 is incident. The lower surface of the heat diffusion suppression member 30 is the exit surface 32 into which the laser beam L that has passed through the heat diffusion suppression member 30 is emitted toward the mask 26. The incident surface 31 and the exit surface 32 are parallel to each other and are planes perpendicular to the Z-axis direction. Therefore, the heat diffusion suppression member 30 transmits the laser beam L traveling in the Z-axis direction towards the mask 26 with almost no refraction or reflection.

[0035] The heat diffusion suppression member 30 positioned above the mask 26 prevents the heated air (high-temperature air K) from diffusing upward along the vertical optical path Pb when heat is generated on the mask 26 due to the irradiation of the laser beam L. In other words, the heat diffusion suppression member 30 prevents the heat generated from the mask 26 from being transmitted to the upstream side of the optical path of the laser beam L via the air.

[0036] The function of the heat diffusion suppression member 30 will be explained in more detail. The heat generated in the mask 26 mainly occurs in the area of ​​the shielding portion 28 where the laser beam L is irradiated around the slit 27 (the area where the laser beam L is shielded by the shielding portion 28). This heat-generating region is located within the range of the beam cross-section Lv (a beam cross-section perpendicular to the optical axis Q) of the laser beam L traveling from the mirror 23 to the mask 26, and in the vicinity of the beam cross-section Lv. Therefore, the hot air K heated by the heat-generating region of the mask 26 forms an upward airflow along the vertical optical path Pb through which the laser beam L passes. Since the heat diffusion suppression member 30 is positioned to cross the beam cross-section Lv, when the hot air K forming the upward airflow hits the heat diffusion suppression member 30, the heat diffusion suppression member 30 prevents the hot air K from continuing upward, causing the hot air K to detour away from the optical axis Q and beam cross-section Lv to the outside of the heat diffusion suppression member 30. Furthermore, as the high-temperature air K bypasses the heat diffusion suppression member 30 and travels outward, it mixes with the surrounding air, which is cooler, and its temperature decreases. As a result, above the heat diffusion suppression member 30, the temperature of the air near the optical axis Q is less likely to rise, and the occurrence of air fluctuations (which affect the stable propagation of the laser beam L) caused by temperature rise is suppressed. In addition, between the mask 26 and the heat diffusion suppression member 30, the high-temperature air K becomes an upward airflow and hits the heat diffusion suppression member 30, forming a flow of high-temperature air K that moves along the exit surface 32 toward the outer edge of the heat diffusion suppression member 30. Therefore, high-temperature air K is less likely to stagnate in the optical path of the laser beam L between the mask 26 and the heat diffusion suppression member 30, and the occurrence of air fluctuations that affect the stable propagation of the laser beam L is suppressed. Thus, the heat diffusion suppression member 30 has an insulating effect that prevents the air above the laser beam L from warming up by suppressing the diffusion of heat generated when the laser beam L is irradiated onto the mask 26 into the optical path of the laser beam L (by moving the heat outside the optical path of the laser beam L).

[0037] As shown in Figures 2 and 3, the horizontal area of ​​the heat diffusion suppression member 30 is larger than the beam cross-section Lv of the laser beam L, and the heat diffusion suppression member 30 is positioned to accommodate the beam cross-section Lv of the laser beam L within its area. In other words, when the heat diffusion suppression member 30 is viewed from above along the Z-axis, the beam cross-section Lv of the laser beam L is contained within the outer shape (contour) of the heat diffusion suppression member 30 (the entire beam cross-section Lv overlaps the heat diffusion suppression member 30). This arrangement of the heat diffusion suppression member 30 provides excellent heat insulation.

[0038] Unlike the configuration of this embodiment, even when the heat diffusion suppression member is viewed in plan along the Z-axis direction, and a portion of the beam cross-section Lv of the laser beam L does not overlap with the heat diffusion suppression member (a portion of the laser beam L passes outside the heat diffusion suppression member), it is still possible to obtain a certain degree of heat insulation by blocking the diffusion (rise) of a portion of the air heated by the heat generated by the mask 26. Therefore, the arrangement of the heat diffusion suppression member in the horizontal direction is not limited to the arrangement of the heat diffusion suppression member 30 in this embodiment.

[0039] When obtaining the thermal insulation effect of the heat diffusion suppression member 30, the distance between the mask 26 and the heat diffusion suppression member 30 in the optical axis direction of the laser beam L (the irradiation direction of the laser beam L) (shown as distance S in Figure 2) is a factor that should be considered. If the distance S between the mask 26 and the heat diffusion suppression member 30 is too small, the thermal insulation effect of the air layer between them will be reduced, and heat will be directly transferred from the mask 26 to the heat diffusion suppression member 30. As a result, the heat diffusion suppression member 30 will heat up in the same way as the mask 26 (the heat diffusion suppression member 30 itself will become a heat source), warming the surrounding air, and there is a risk that the thermal insulation effect of the heat diffusion suppression member 30 will not be obtained. If the distance S between the mask 26 and the heat diffusion suppression member 30 is too large, events such as the accumulation of high-temperature air K in the optical path between the mask 26 and the heat diffusion suppression member 30 may occur, and there is a risk that the thermal insulation effect of the heat diffusion suppression member 30 will not be obtained.

[0040] Figure 4 shows the results of the first experiment conducted to find a suitable distance S between the mask 26 and the heat diffusion suppression member 30. In this experiment, the laser irradiation unit 20 was operated while varying the distance S between the mask 26 and the heat diffusion suppression member 30, and a laser beam L was irradiated onto the object to be processed 1 on the holding table 12. The extent to which the laser processing marks formed on the object to be processed 1 were misaligned from the position under the original processing conditions was verified. In the first experiment, the thickness of the heat diffusion suppression member 30 in the optical axis direction was within the range (0.1 mm to 1.0 mm) for which good results were obtained in the second experiment described later. In addition, processing conditions other than the distance S (such as the repetition frequency and pulse width of the laser beam L) were common in each processing step.

[0041] A laser processing mark is considered defective if the positional deviation of the laser processing mark actually formed relative to the processing position on the object 1 set as a processing condition exceeds a standard value (the allowable error range in the laser beam irradiation device 10), and good if it is within the standard value. When the distance S between the mask 26 and the heat diffusion suppression member 30 is 0.05 mm, the heat diffusion suppression member 30 is heated along with the heat generated by the mask 26, weakening the heat insulation effect, and the irradiation position of the laser beam L becomes unstable due to air fluctuations in the vertical optical path Pb, resulting in a laser processing mark positional deviation exceeding the standard value. When the distance S between the mask 26 and the heat diffusion suppression member 30 is 5.1 mm, the heat insulation effect is not achieved between the mask 26 and the heat diffusion suppression member 30, and the irradiation position of the laser beam L becomes unstable due to air fluctuations in part of the vertical optical path Pb with the mask 26 as a heat source, resulting in a laser processing mark positional deviation exceeding the standard value. When the distance S between the mask 26 and the heat diffusion suppression member 30 was 0.1 mm, 0.5 mm, 1.0 mm, 2.5 mm, and 5.0 mm, the positional displacement of the laser processing marks was within the standard range in all cases, and good processing results were obtained. From these experimental results, it is preferable that the distance S between the mask 26 and the heat diffusion suppression member 30 in the optical axis direction of the laser beam L is between 0.1 mm and 5 mm.

[0042] Furthermore, when the gap S between the mask 26 and the heat diffusion suppression member 30 was 0.05 mm, the positional displacement of the laser processing marks was greater than when the gap S was 5.1 mm. The reason for this difference in results is thought to be that when the gap S was too small (0.05 mm), the heat diffusion suppression member 30 itself became a heat source along with the mask 26, as described above, and the heat insulation effect of the heat diffusion suppression member 30 could not be obtained in the entire space above the heat diffusion suppression member 30, resulting in heat-induced air fluctuations over a wide area of ​​the vertical optical path Pb. When the gap S was too large (5.1 mm), while the heat insulation effect was obtained above the heat diffusion suppression member 30, it is thought that the accumulation of high-temperature air K occurred between the mask 26 and the heat diffusion suppression member 30, causing partial air fluctuations in the vertical optical path Pb.

[0043] When obtaining the thermal insulation effect of the heat diffusion suppression member 30, the thickness of the heat diffusion suppression member 30 in the optical axis direction of the laser beam L (the irradiation direction of the laser beam L) (shown as thickness T in Figure 2) is also a factor that should be considered. If the thickness T of the heat diffusion suppression member 30 is too small (too thin), the heat received at the exit surface 32 facing the mask 26, which is the heat source, will be transmitted to the incident surface 31 on the opposite side, causing the heat diffusion suppression member 30 to heat up, and there is a risk that heat will be transferred to the air above the heat diffusion suppression member 30. If the thickness T of the heat diffusion suppression member 30 is too large (too thick), even if the heat diffusion suppression member 30 is made of a material that transmits the laser beam L, absorption of the laser beam L will occur in the heat diffusion suppression member 30, causing slight distortion, which may hinder the normal transmission of the laser beam L.

[0044] Figure 5 shows the results of a second experiment conducted to find a suitable thickness T for the heat diffusion suppression member 30. In this experiment, the laser irradiation unit 20 was operated while switching between multiple heat diffusion suppression members 30 with different thicknesses T, and a laser beam L was irradiated onto the object to be processed 1 on the holding table 12. The extent of positional displacement of the laser processing marks formed on the object to be processed 1 relative to the position under the original processing conditions was verified. In the second experiment, the distance between the mask 26 and the heat diffusion suppression member 30 in the optical axis direction was set to a predetermined value within the range (0.1 mm to 5.0 mm) for which good results were obtained in the first experiment described above. In addition, processing conditions other than thickness T (such as the repetition frequency and pulse width of the laser beam L) were common in each processing cycle.

[0045] Similar to the first experiment described above, if the positional deviation of the laser processing mark actually formed relative to the processing position on the object 1 set as the processing condition is greater than or equal to the reference value (the error range permissible in the laser beam irradiation device 10), it is considered a failure; if it is within the reference value, it is considered a success. When the thickness T of the heat diffusion suppression member 30 was 0.05 mm, the heat generated by the mask 26 was transferred to the entire thickness direction of the heat diffusion suppression member 30, resulting in no heat insulation effect. As a result, the irradiation position of the laser beam L was unstable due to air fluctuations in the vertical optical path Pb with the mask 26 and the heat diffusion suppression member 30 as heat sources, causing a positional deviation of the laser processing mark greater than the reference value. When the thickness T of the heat diffusion suppression member 30 was 1.1 mm, the heat diffusion suppression member 30 absorbed the laser beam L, causing distortion of its shape. As a result, the irradiation position of the laser beam L that passed through the heat diffusion suppression member 30 was unstable, causing a positional deviation of the laser processing mark greater than the reference value. When the thickness T of the heat diffusion suppression member 30 was 0.1 mm, 0.2 mm, 0.3 mm, 0.5 mm, and 1.0 mm, the positional displacement of the laser processing marks was within the standard range in all cases, and good processing results were obtained. From these experimental results, it is preferable that the thickness T of the heat diffusion suppression member 30 in the optical axis direction of the laser beam L is between 0.1 mm and 1.0 mm.

[0046] Furthermore, when the thickness T of the heat diffusion suppression member 30 was 0.05 mm, the positional displacement of the laser processing marks was greater than when the thickness T was 1.1 mm. The reason for this difference in results is presumed to be that the air fluctuations caused by the loss of the heat insulation effect of the heat diffusion suppression member 30 when the thickness T is too small (0.05 mm) have a greater impact on the straightness of the laser beam L than the slight shape distortion of the heat diffusion suppression member 30 when the thickness T is too large (1.1 mm).

[0047] As can be seen from the experimental results above, it is desirable that the heat diffusion suppression member 30 placed on top of the mask 26 satisfies the predetermined conditions described above with respect to the distance S from the mask 26 in the optical axis direction and the thickness T in the optical axis direction. Note that the numerical increments for the distance S and thickness T in each experiment are just examples, and experiments may be conducted with even smaller numerical increments, and the suitable ranges for the distance S and thickness T may be updated based on the experimental results.

[0048] The heat diffusion suppression member 30 is a simple plate-shaped member, and if the quartz glass exemplified earlier is used as the material for the heat diffusion suppression member 30, it can be introduced at a relatively low cost. The heat diffusion suppression member of this disclosure only needs to have a portion that transmits the laser beam L (a predetermined range including the beam cross-section Lv) made of a material that is transparent to the laser beam L, and the portion other than the laser beam L transmission portion may be made of a different material. For example, the central portion of the heat diffusion suppression member that transmits the laser beam L may be made of quartz glass that is transparent to the laser beam L, and the outer portion may be made of a different material such as metal or synthetic resin. Such an outer portion can be used as a holder for attaching the heat diffusion suppression member 30 inside the processing head 25. Furthermore, although the heat diffusion suppression member 30 shown in Figure 3 is a rectangular plate, the shape of the heat diffusion suppression member in this disclosure is not limited to this. For example, the heat diffusion suppression member may be disc-shaped or a polygonal shape other than a rectangle.

[0049] The modified thermal diffusion suppression member 35 shown in Figure 6 not only receives the high-temperature air K rising from the side of the mask 26, which is heated by the irradiation of the laser beam L, but also includes a rectifier section 36 that guides the high-temperature air K away from the optical path of the laser beam L. The central portion of the thermal diffusion suppression member 35 that transmits the laser beam L is a flat plate shape, similar to the thermal diffusion suppression member 30 described above, having an incident surface 31 and an exit surface 32 that are planes perpendicular to the optical axis Q and parallel to each other, and transmits the laser beam L with almost no refraction or reflection. The rectifier section 36 provided on the outer part of the thermal diffusion suppression member 35 is formed as a wall portion that slopes away from the optical axis Q as it moves upward in the Z-axis direction (+Z direction). Specifically, the rectifier section 36 has a shape like the side surface of a cone or pyramid centered on the optical axis Q.

[0050] When high-temperature air K rises from the side of the heated mask 26, the high-temperature air K that hits the central part of the heat diffusion suppression member 35 forms a flow that bypasses it towards the rectifier section 36. The inclined shape of the rectifier section 36 has the effect of guiding the high-temperature air K rising along the rectifier section 36 away from the optical axis Q, reliably preventing the high-temperature air K from mixing with the air in the vertical optical path Pb and causing fluctuations.

[0051] The modified thermal diffusion suppression member 37 shown in Figure 7 has a surrounding portion 38 extending upward in the Z-axis direction (+Z direction) around a central portion of a flat plate shape that transmits the laser beam L. The surrounding portion 38 is a wall portion that surrounds the vertical optical path Pb and has a shape like the side of a cylinder or rectangular tube centered on the optical axis Q.

[0052] When high-temperature air K rises from the side of the heated mask 26, a flow is formed in which the high-temperature air K that hits the central part of the heat diffusion suppression member 37 bypasses towards the surrounding portion 38. The surrounding portion 38 shields the high-temperature air K rising along the outer surface of the surrounding portion 38 from the air on the inside of the surrounding portion 38 (vertical optical path Pb side), reliably preventing the high-temperature air K from mixing with the air in the vertical optical path Pb and causing fluctuations.

[0053] As can be seen from the modified examples in Figures 6 and 7, the heat diffusion suppression member of this disclosure is not limited to a simple plate shape, and can have various configurations to enhance the effect of preventing the temperature of the air in the optical path through which the laser beam L passes from rising.

[0054] Next, a method for processing the object to be processed 1 by irradiating it with a laser beam L using the laser beam irradiation device 10 configured as described above (laser beam irradiation method, chip manufacturing method) will be explained. The laser beam irradiation method and chip manufacturing method described below will be explained based on the heat diffusion suppression member 30 shown in Figures 2 and 3, but the heat diffusion suppression member 35 shown in Figure 6 and the heat diffusion suppression member 37 shown in Figure 7 can also be applied, in which case the heat diffusion suppression member 30 will be replaced with the heat diffusion suppression member 35 or the heat diffusion suppression member 37.

[0055] The operation of each part of the laser beam irradiation device 10 is controlled by the control unit 42. The control unit 42 controls the X-axis movement mechanism 16, the table rotation mechanism 17, the Y-axis movement mechanism 18, the Z-axis movement mechanism 19, the laser irradiation unit 20, and other components according to a control program stored in memory.

[0056] [Holding step] In the holding step, the object to be processed 1 is held by the holding table 12. The object to be processed 1 is transported to the laser beam irradiation device 10 in the form of an object to be processed unit 7 attached to the inside of the frame 6 via tape 5. As shown in Figure 2, the object to be processed 1 is placed on the holding surface 13 of the holding table 12 via tape 5, and the frame 6 is held by the clamp part 15. Negative pressure is applied to the holding surface 13 by the operation of the suction source 14, and the object to be processed 1 is held in place by suction on the holding table 12.

[0057] The control unit 42 operates the X-axis movement mechanism 16 and the Y-axis movement mechanism 18 to position the object to be processed 1, held on the holding table 12, below the processing head 25 of the laser irradiation unit 20. Based on the image of the object to be processed 1 captured by the imaging unit 41, the control unit 42 adjusts the relative positional relationship between the object to be processed 1 and the processing head 25 in the X-axis and Y-axis directions so that the laser beam L is irradiated from the processing head 25 to a desired position on the object to be processed 1. The control unit 42 also operates the Z-axis movement mechanism 19 to adjust the height position of the laser irradiation unit 20 so that the laser beam L, focused by the focusing lens 24 of the laser irradiation unit 20, is focused to a desired position in the thickness direction (Z-axis direction) of the object to be processed 1.

[0058] [Irradiation step, splitting step] Following the holding step, the irradiation step is performed. In the irradiation step, the laser beam L output from the laser light source 21 is irradiated onto the object to be processed 1 via the optical system of the laser irradiation unit 20. The optical system of the laser irradiation unit 20 is equipped with a mask 26 in addition to a mirror 23 and a focusing lens 24. A portion of the output laser beam L is blocked from passing by the shielding portion 28 of the mask 26, and only the laser beam L that passes through the slit 27 of the mask 26 is focused by the focusing lens 24 and irradiated onto the object to be processed 1.

[0059] During the irradiation step, a heat diffusion suppression member 30, positioned above the mask 26, suppresses the diffusion of heat generated when the laser beam L is irradiated onto the shielding portion 28 of the mask 26 into the optical path of the laser beam L. This prevents air fluctuations in the optical path through which the laser beam L passes, allowing the laser beam L irradiated onto the object to be processed 1 to be focused to a precise position corresponding to the processing conditions, enabling highly accurate processing.

[0060] The processing performed in the irradiation step carried out by the laser beam irradiation device 10 varies. In this embodiment, the laser beam irradiation device 10 performs processing on the object to be processed 1, specifically dividing the object to be processed 1 based on the planned division line 4 on the street 2 to create individual chips 3, that is, processing related to the manufacture of chips 3. Therefore, when the technology of this disclosure is applied to a chip manufacturing method, the irradiation step is included in the division step. The division step can be divided into two forms: one in which the object to be processed 1 is divided into multiple chips 3 starting from laser processing marks formed by irradiating it with a laser beam L, and another in which the object is divided into multiple chips 3 by forming laser processing marks that remove the street 2.

[0061] Figure 8 shows the state in which laser processing is being performed on the object to be processed 1 by irradiating it with a laser beam L along the planned division line 4. The laser beam L is a pulsed laser with a wavelength that is absorbed by the object to be processed 1. By aligning the position of the focal point of the laser beam L, which is focused by the focusing lens 24, with the planned division line 4 on the object to be processed 1, removal or modification of the object to be processed 1 occurs in the areas that are ablated by the laser beam L. The planned division line 4 shown as a dashed line in Figure 8 is before irradiation with the laser beam L. The irradiation completed portion 50 shown as a solid line in Figure 8 is the portion of Street 2 after irradiation with the laser beam L. In the irradiation completed portion 50, laser processing marks such as full-cut grooves 51, half-cut grooves 52, and modified portions 53, which will be described later, are formed along the planned division line 4.

[0062] Machining along each street 2 of the object to be processed 1 is performed, for example, as follows: The control unit 42 controls the X-axis movement mechanism 16 and the Y-axis movement mechanism 18 to position the irradiation position of the laser beam L on the object to be processed 1 at one end (start end) of any of the multiple division lines 4 extending in the X-axis direction. Then, the X-axis movement mechanism 16 is operated to move the holding table 12 and the laser irradiation unit 20 relatively in the X-axis direction (machining feed) so that the irradiation position of the laser beam L changes along the division line 4, while the laser beam L is irradiated onto the object to be processed 1 from the machining head 25. As a result, laser machining is performed along one of the division lines 4 (a laser machining mark is formed). When the irradiation position of the laser beam L reaches the other end (end) of the division line 4, the irradiation of the laser beam L from the laser irradiation unit 20 is stopped. Next, the X-axis movement mechanism 16 and the Y-axis movement mechanism 18 are operated to position the irradiation position of the laser beam L at one end (start end) of the next planned division line 4. Then, while performing the processing feed operation in the X-axis direction as described above, the laser beam L is irradiated onto the workpiece 1, and laser processing is performed along the next planned division line 4 (a laser processing mark is formed). Once processing along all the planned division lines 4 aligned in the X-axis direction is completed, the table rotation mechanism 17 is operated to rotate the holding table 12 by 90 degrees. This leaves the unprocessed planned division lines 4 extending in the X-axis direction. Then, using the same procedure as described above, the laser beam L is irradiated along these unprocessed planned division lines 4 and processing is performed sequentially. In this way, processing is performed along all the streets 2 on the workpiece 1.

[0063] As a first form of processing along the planned division line 4, the street 2 is removed by irradiating the workpiece 1 with a laser beam L, thereby forming a full-cut groove 51 as a laser processing mark. The formation of the full-cut groove 51 completely separates the chips 3 located on both sides of the street 2. When forming a full-cut groove 51 along the planned division line 4 on the workpiece 1, the division into multiple chips 3 is completed when the irradiation step performed by the laser beam irradiation device 10 is completed.

[0064] As a second form of processing along the planned division line 4, the street 2 is removed up to a certain point in the thickness direction of the workpiece 1 by irradiation with a laser beam L, forming a half-cut groove 52 as a laser processing mark. The half-cut groove 52 is a bottomed groove formed on the workpiece 1 from the upper surface to which the laser beam L is irradiated to a predetermined depth. Below the half-cut groove 52, the chips 3 on both sides of the street 2 are connected without being divided.

[0065] As a third form of processing along the planned division line 4, a modified portion 53 is formed inside the object to be processed 1 in the thickness direction by irradiation with a laser beam L. The modified portion 53 is a part whose strength is reduced compared to the surrounding area. In addition, cracks 54 may extend from the modified portion 53. Multiple modified portions 53 are formed at predetermined intervals along the planned division line 4 that extends in the X-axis direction and the Y-axis direction. Note that multiple layers of modified portions 53 may be formed at different positions in the thickness direction of the object to be processed 1.

[0066] When forming half-cut grooves 52 or modified sections 53 along the planned division line 4 on the object to be processed 1, the object to be processed 1 is divided starting from the half-cut grooves 52 or modified sections 53, and multiple chips 3 are manufactured. The division of the object to be processed 1 starting from the half-cut grooves 52 or modified sections 53 may occur spontaneously from the starting point, or an additional processing step for division may be performed after the irradiation step.

[0067] As an example of an additional processing step for division, an expansion operation (external force application step) is performed using an expander different from the laser beam irradiation device 10 to expand the tape 5 supporting the object to be processed 1. When the tape 5 is expanded, an external force is applied that expands the object to be processed 1 to which the tape 5 is attached in the radial direction, and the division of the object to be processed 1 proceeds from the starting points such as the half-cut grooves 52 and modified sections 53, where the strength is reduced.

[0068] In addition to dividing the undivided streets 2, the expansion of tape 5 also has the effect of increasing the spacing between already divided chips 3. By increasing the spacing between chips 3, it becomes easier to remove the individual chips 3 from tape 5. Therefore, if the object to be processed 1 has already been divided into chips 3 at the stage of the irradiation step (for example, if a full-cut groove 51 is formed or if division occurs spontaneously starting from the modified section 53), the tape 5 may be expanded using an expander to increase the spacing between adjacent chips 3.

[0069] As a different example of an additional processing step for division, a pressing device different from the laser beam irradiation device 10 is used to press the tape 5 supporting the object to be processed 1 (external force application step). For example, by pressing a roller that can rotate around the Y-axis axis against the object to be processed 1 and moving the roller in the X-axis direction, an external force is applied to the object to be processed 1, causing it to be divided into multiple chips 3. Since the tape 5 is expanded by the pressure of the roller, the pressing device can be used not only for dividing the object to be processed 1 but also for increasing the spacing between the divided chips 3, similar to the case of the expander described above.

[0070] As an example of an additional processing step for splitting, after forming half-cut grooves 52 and modified sections 53 along the street 2 in the irradiation step, the workpiece 1 may be transported to a grinding device and the back side opposite to the front surface of the chip 3 may be ground. During grinding, a rotating grinding wheel is pressed against the back side of the workpiece 1 with a predetermined pressure. The grinding pressure applied to the workpiece 1 from the grinding wheel can cause the splitting of the workpiece 1 to proceed, starting from the half-cut grooves 52 and modified sections 53.

[0071] As an example of an additional processing step for segmentation, it is also possible to form a half-cut groove 52 along the street 2 in the irradiation step, then transport the object to be processed 1 to a plasma processing device and perform plasma etching on the object to be processed 1. By performing plasma etching on the area of ​​the half-cut groove 52, the street 2 is removed so that the half-cut groove 52 deepens and penetrates in the thickness direction, and the object to be processed 1 is fragmented into multiple chips 3.

[0072] Figure 9 shows different examples of processing performed in the irradiation step. A low-k film 55, a low dielectric constant insulating film, is provided on the surface side of the object to be processed 1. The low-k film 55 has low mechanical strength, and if blade dicing is performed to divide the object to be processed 1 by cutting a cutting blade along the planned division line 4, there is a risk of peeling of the low-k film 55. Therefore, processing to remove the low-k film 55 by irradiation with a laser beam (low-k grooving) is performed, and the object to be processed 1 is divided by cutting a cutting blade into the street 2 after the low-k film 55 has been removed. Figure 9 shows the irradiation step performed by the laser beam irradiation device 10 applied to the removal of such a low-k film 55.

[0073] As shown in Figure 9, a Low-k film 55 is provided on the surface (top) side of the object to be processed 1, and the Low-k film 55 is further covered with a protective film 56. The laser beam L irradiated onto the object to be processed 1 from the laser irradiation unit 20 is a pulsed laser with a wavelength that is absorbed by the Low-k film 55. The protective film 56 is made of a water-soluble resin or the like that is transparent to the laser beam L.

[0074] The control unit 42 controls the focusing position of the laser irradiation unit 20 so that the laser beam L emitted from the laser irradiation unit 20 is focused on the Low-k film 55. The control unit 42 then irradiates the laser beam L along the division line 4. The Low-k film 55 is removed by ablation at the location irradiated by the laser beam L. The protective film 56 prevents debris generated during ablation from scattering into the surroundings and adhering to the surface of the chip 3.

[0075] When the laser beam L of the laser irradiation unit 20 is a flat-top beam (top-hat beam) with a generally constant radiation intensity at the beam cross-section Lv, passing the laser beam L through the slit 27 of the mask 26 enables the formation of a laser beam suitable for processing along a street 2, as shown in the processing examples in Figures 8 and 9 (where the irradiation range of the laser beam L does not extend to the chips 3 on both sides of the street 2). Therefore, the laser beam irradiation apparatus and laser beam irradiation method of this disclosure, which solve the problem of heat generation when the laser beam L is irradiated onto the mask 26 of the laser irradiation unit 20, are highly useful when performing processing along a street 2, as shown in Figures 8 and 9. Specifically, the processing shown in Figures 8 and 9 is at least part of a process that divides the workpiece 1 to manufacture chips 3. Therefore, the laser beam irradiation apparatus and laser beam irradiation method of this disclosure can be particularly effective when applied to a method for manufacturing chips.

[0076] In the above embodiment, the laser beam irradiation device 10 performs processing with the object to be processed 1 held on a ring-shaped frame 6 via a tape 5 (object to be processed unit 7). However, the laser beam irradiation device, laser beam irradiation method, and chip manufacturing method of this disclosure can also be applied when processing an object to be processed that is not attached to a tape and frame. For example, in processing to form a half-cut groove 52 or a modified portion 53 as shown in Figure 8, or in processing to partially remove a Low-k film 55 as shown in Figure 9, if the object to be processed 1 is not fragmented into individual pieces but maintains a unified structure during the irradiation step, the chips 3 will not dissipate even if the object to be processed 1 is not supported by the tape 5. Furthermore, when forming the half-cut grooves 52 or the modified section 53, or removing the Low-k film 55, the focal point of the laser beam L is set to a position that does not reach the lower surface of the object to be processed 1 that is held by the holding table 12. Therefore, even when the object to be processed 1 is not supported by the tape 5, the energy of the laser beam L processing the object to be processed 1 is unlikely to reach the holding table 12 and cause damage. Consequently, when forming the half-cut grooves 52 or the modified section 53, or removing the Low-k film 55, the object to be processed 1 may be processed by holding only the object to be processed 1 on the holding table 12 without attaching the tape 5 and frame 6 to the object to be processed 1. Also, when the tape 5 is not expanded by the expander, the laser beam irradiation device 10 may process the object to be processed 1 with only the tape or flat support plate attached, without using the ring-shaped frame 6.

[0077] The optical system of the laser beam irradiation device 10 in the above embodiment is configured to irradiate a laser beam L downward from a laser irradiation unit 20 positioned above the object to be processed 1. However, an optical system configured to irradiate a laser beam L upward from below the object to be processed 1, as shown in Figure 10 with the laser irradiation unit 60, may also be applied. With regard to the components of the laser irradiation unit 60, those that are common with the laser irradiation unit 20 in the above embodiment are indicated by the same reference numerals and detailed explanations are omitted.

[0078] The holding table 61 that holds the object to be processed 1 is made of a material (such as quartz glass) that transmits the laser beam L without absorbing it. The processing head 62 of the laser irradiation unit 60 is positioned below the holding table 61. The laser beam L output from the laser light source 21 is reflected upward by the mirror 23 and travels upward through the vertical optical path Pb in the processing head 62. A focusing lens 24 is positioned above the mirror 23 in the vertical optical path Pb, and a mask 26 is positioned between the mirror 23 and the focusing lens 24. The mask 26 allows the laser beam L to pass through the slit 27 and blocks the laser beam L with a shielding portion 28 around the slit 27. The laser beam L that has passed through the slit 27 is focused by the focusing lens 24, enters from the lower side of the holding table 61, passes through the holding table 61, and is irradiated onto the object to be processed 1 held on the upper side of the holding table 61 to perform processing (machining).

[0079] A heat diffusion suppression member 63 is positioned on the upper part of the mask 26. In other words, the heat diffusion suppression member 63 is positioned between the focusing lens 24 and the mask 26 in the optical axis direction of the laser beam L. The heat diffusion suppression member 63 is made of a material that is transparent to the laser beam L (for example, quartz glass). The heat diffusion suppression member 63 configured in this way acts in the same way as the heat diffusion suppression member 30 in the above embodiment. Specifically, when the laser beam L is irradiated onto the shielding portion 28 of the mask 26 and heat is generated, the hot air heated by the heat-generating region of the mask 26 forms an upward airflow. When the rising hot air hits the heat diffusion suppression member 63, the hot air moves in a direction that bypasses the heat diffusion suppression member 63 (i.e., away from the optical axis Q of the laser beam L). This suppresses the generation of fluctuations in the air along the optical path that would affect the stable propagation of the laser beam L. Therefore, the heat diffusion suppression member 63 has an insulating effect that prevents the air in the optical path through which the laser beam L passes from warming up when the mask 26 generates heat.

[0080] In the configuration shown in Figure 10, the object to be processed 1 is held on the upper side of the holding table 61 that transmits the laser beam L. However, a holding table with a structure that holds the object to be processed 1 by suction on the lower side (a structure similar to the holding table 12 shown in Figure 2 but inverted) may also be used. The laser irradiation unit 60 irradiates the object to be processed 1, which is held by suction on the lower side of the holding table, with the laser beam L. In this case, the holding table does not need to be made of a material that transmits the laser beam L.

[0081] As described above, the high-temperature air heated by the heat generated by the mask 26 forms an upward airflow. Therefore, in both the laser irradiation unit 20 (see Figures 2 and 3) where the optical system is positioned above the object to be processed 1, and the laser irradiation unit 60 (see Figure 10) where the optical system is positioned below the object to be processed 1, it is extremely useful to place the heat diffusion suppression member 30 or heat diffusion suppression member 63 at least above the mask 26 (a position that prevents heat diffusion due to the rising of high-temperature air). However, the technology of this disclosure does not exclude the placement of the heat diffusion suppression member not only above the mask 26 but also below it. For example, if there is a risk of high-temperature air moving below the mask 26 due to convection or circulation of the air around the mask 26, placing the heat diffusion suppression member below the mask 26 can prevent heat from the mask 26 from diffusing into the laser beam path below, thereby improving the stability of the laser beam L processing of the object to be processed 1.

[0082] Furthermore, the embodiments of the present invention are not limited to the embodiments and modifications described above, and may be modified, substituted, or altered in various ways without departing from the spirit of the technical idea of ​​the present invention. Moreover, if the technical idea of ​​the present invention can be realized in a different way by advances in the art or by other derived arts, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea of ​​the present invention. [Industrial applicability]

[0083] According to the present invention, in a laser beam irradiation device equipped with a mask that generates heat upon irradiation with a laser beam, the heat diffusion suppression member can suppress the diffusion of heat, thereby improving the stability of laser processing and contributing to improvements in quality and productivity in the manufacturing of chips using laser processing. [Explanation of Symbols]

[0084] 1: Object to be processed 2: Street 3: Tip 4: Planned division line 5: Tape 6: Frame 7: Processing Unit 10: Laser beam irradiation device 12: Holding table (holding part) 16:X-axis movement mechanism 17: Table rotation mechanism 18:Y-axis movement mechanism 19:Z-axis movement mechanism 20: Laser irradiation unit 21: Laser light source 22: Output adjustment section 23: Miller 24: Focusing lens 25: Machining head 26: Mask 27: Slit 28: Shielding part 30: Heat diffusion suppression member 31:Incidence plane 32: Ejection surface 35: Heat diffusion suppression member 36: Rectifier 37: Heat diffusion suppression member 38: Enclosing part 41: Imaging Unit 42: Control Unit 50: Irradiation completed part 51: Full cut groove (laser processing marks) 52: Half-cut groove (laser processing mark) 53: Modified area (laser processing marks) 54: Crack 55:Low-k film 56:Protective film 60: Laser irradiation unit 61: Holding Table 62: Machining head 63: Heat diffusion suppression member K: High-temperature air L: Laser beam Lv: Beam Cross Section Pa:Horizontal optical path Pb: Vertical optical path Q: Optical axis S: Distance between the mask and the heat diffusion suppression member T: Thickness of the heat diffusion suppression member

Claims

1. A laser beam irradiation device that irradiates an object to be processed with a laser beam, A holding unit for holding the object to be processed, A laser light source that outputs the laser beam, A mask that blocks a portion of the laser beam emitted from the laser light source and allows a portion to pass through, A focusing lens that focuses the laser beam that has passed through the mask, A heat diffusion suppression member is provided at the top of the mask, which transmits the laser beam and suppresses the diffusion of heat generated when the mask is irradiated with the laser beam, A laser beam irradiation device equipped with the following features.

2. The heat diffusion suppressing member is Arranged to accommodate the cross-section of the laser beam, The laser beam irradiation device according to claim 1, characterized in that at least the region through which the beam passes is formed of a material that is transparent to the laser beam.

3. The laser beam irradiation device according to claim 1 or 2, characterized in that the distance between the mask and the heat diffusion suppression member in the optical axis direction of the laser beam is 0.1 mm or more and 5 mm or less.

4. The laser beam irradiation device according to claim 1 or 2, characterized in that the thickness of the heat diffusion suppressing member in the optical axis direction of the laser beam is 0.1 mm or more and 1 mm or less.

5. A laser beam irradiation method for irradiating an object to be processed with a laser beam, A holding step in which the object to be processed is held in the holding unit, The process includes an irradiation step of irradiating an object to be processed with a laser beam output from a laser light source via an optical system, The optical system is, A mask that blocks a portion of the laser beam emitted from the laser light source and allows a portion to pass through, A focusing lens that focuses the laser beam that has passed through the mask, A heat diffusion suppression member is provided at the top of the mask, which transmits the laser beam and suppresses the diffusion of heat generated when the mask is irradiated with the laser beam, A laser beam irradiation method comprising the following features.

6. A method for manufacturing chips, which involves irradiating a workpiece with a laser beam to divide it into multiple chips, A holding step in which the workpiece is held in the holding part, The system includes a division step in which a laser beam output from a laser light source is irradiated onto a workpiece via an optical system to form laser processing marks, and the workpiece is divided into multiple chips starting from the laser processing marks, or the workpiece is divided into multiple chips by the laser processing marks, The optical system is, A mask that blocks a portion of the laser beam emitted from the laser light source and allows a portion to pass through, A focusing lens that focuses the laser beam that has passed through the mask, A heat diffusion suppression member is provided at the top of the mask, which transmits the laser beam and suppresses the diffusion of heat generated when the mask is irradiated with the laser beam, A method for manufacturing a chip equipped with the following features.

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