Laser processing apparatus, laser processing method, and method for manufacturing device chips

Abstract

The present invention provides a laser processing apparatus and a laser processing method that can suppress the transfer of heat to the optical path of a laser beam. [Solution] The laser processing apparatus 2 comprises a holding table 6 for holding a workpiece 1 and a laser beam irradiation unit 8 for irradiating the workpiece 1 with a laser beam. The laser beam irradiation unit 8 includes a laser oscillator 38, a focusing lens 50, and a mask portion 44 disposed between the laser oscillator 38 and the focusing lens 50 to shield a portion of the laser beam. The mask portion 44 has a reflecting portion 56 that reflects the shielded laser beam. The laser beam irradiation unit 8 further includes a heat dissipation portion 45 that receives the reflected light reflected by the reflecting portion 56 and dissipates the heat generated by the reflected light.

Description

Technical Field

[0001] The present invention relates to a laser processing apparatus and a laser processing method.

Background Art

[0002] For device chips such as ICs (Integrated Circuits) mounted with semiconductor devices, a low dielectric constant insulator film (Low-k film) having a low dielectric constant, for example, is used as an interlayer insulating film between wiring layers. Since the Low-k film is a very brittle film, for example, Patent Document 1 proposes a wafer dicing method in which a wafer is diced with a cutting blade after removing the Low-k film by irradiating it with a laser beam.

[0003] Further, Patent Document 2 also proposes a laser processing apparatus that suppresses peeling of the Low-k film from the semiconductor wafer when removing the Low-k film by irradiating it with a laser beam. Specifically, the laser processing apparatus of Patent Document 2 trims the skirt portion of the laser beam having a Gaussian distribution to correct the energy distribution. As a means for correcting the energy distribution, a mask member provided with a slit is described, and the mask member shields the skirt portion of the Gaussian distribution to correct the energy distribution of the laser beam.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 2, the mask member absorbs the laser beam and generates heat, which can cause a mirage to occur in the optical path of the laser beam. Since the occurrence of a mirage makes laser processing unstable, there was room for consideration of a configuration that can suppress the transfer of heat to the optical path of the laser beam.

[0006] The present invention provides a laser processing apparatus and a laser processing method that can suppress the transfer of heat to the optical path of a laser beam. [Means for solving the problem]

[0007] The present invention A holding table for holding the workpiece, A laser processing apparatus comprising: a laser beam irradiation unit that irradiates a workpiece held on the holding table with a laser beam; The aforementioned laser beam irradiation unit is A laser oscillator that emits the aforementioned laser beam, A focusing lens that focuses the laser beam and irradiates it onto the workpiece held on the holding table, It has a mask portion disposed between the laser oscillator and the focusing lens, which shields a portion of the laser beam, The mask portion has a reflective portion that reflects the shielded laser beam, The laser beam irradiation unit further includes a heat dissipation unit that receives the reflected light reflected by the reflecting unit and dissipates the heat generated by the reflected light.

[0008] Furthermore, the present invention is A holding step in which the workpiece is held on a holding table, A laser processing method comprising: a laser beam irradiation step of irradiating a workpiece held on the holding table with a laser beam, The laser beam irradiation step involves irradiating the workpiece with a laser beam through a mask portion having a reflective portion provided on the optical path of the laser beam, such that a portion of the laser beam is shielded by the mask portion. The laser processing method further comprises a heat dissipation step of receiving reflected light reflected by the reflecting part and activating a heat dissipation part that dissipates the heat generated by the reflected light. [Effects of the Invention]

[0009] According to the present invention, since a mask portion having a reflective portion and a heat dissipation portion that receives reflected light and dissipates the heat generated by the reflected light are provided, the transfer of heat to the optical path of the laser beam can be suppressed. As a result, the occurrence of mirages in the optical path of the laser beam can be suppressed, and stable laser processing can be performed. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view of workpiece 1. [Figure 2] Figure 2 is a schematic side view showing the configuration of a laser processing apparatus 2 according to one embodiment of the present invention. [Figure 3] Figure 3(A) is a perspective view showing an example of the mask portion 44, Figure 3(B) is a schematic perspective view showing another example of the mask portion 44, and Figure 3(C) is a schematic perspective view showing another example of the mask portion 44. [Figure 4] Figure 4 is a side view of the mask section 44 provided in the optical path of the laser beam. [Figure 5] Figure 5 is a schematic diagram showing an example of the heat dissipation section 45. [Figure 6] Figure 6 is a schematic diagram showing another example of the heat dissipation section 45. [Figure 7] Figure 7 is a side view of the laser beam irradiation unit 8 of the modified example 1. [Figure 8] Figure 8 is a side view of the laser beam irradiation unit 8 of the modified example 2. [Figure 9] Figure 9 is a flowchart of a laser processing method according to one embodiment of the present invention. [Modes for carrying out the invention]

[0011] Hereinafter, an embodiment of the laser processing apparatus and the laser processing method of the present invention will be described based on the accompanying drawings. First, the workpiece of the laser processing apparatus and the laser processing method will be described.

[0012] [Workpiece] FIG. 1 is a perspective view of the workpiece 1. The workpiece 1 is, for example, a substrate made of a material such as silicon, SiC (silicon carbide), or other semiconductors, or a material such as sapphire, glass, or quartz. The workpiece 1 may be, for example, a molded resin substrate in which a substrate on which a device is formed is sealed with resin, or a laminated substrate of a semiconductor wafer and resin.

[0013] The surface of the workpiece 1 is partitioned into a plurality of regions by a plurality of processing planned lines (streets) 3 that intersect, and a device 5 such as an IC (Integrated Circuit) is formed in each partitioned region. Finally, by dividing the workpiece 1 along the processing planned line 3, individual device chips are formed.

[0014] The device 5 has a functional layer including a plurality of wiring layers and an interlayer insulating film that insulates between the wiring layers. In recent years, in order to reduce the parasitic capacitance formed between the wiring layers, a low dielectric constant insulator film (Low-k film) with a low dielectric constant is used for the interlayer insulating film and the like. When a Low-k film is used for the interlayer insulating film, the parasitic capacitance can be reduced and the processing ability of the device chip and the like can be improved. Known Low-k films include inorganic films such as SiOF and SiOB (borosilicate glass), and organic films such as polyimide-based and parylene-based polymer films.

[0015] A tape 7 is adhered to a metal frame 9 on the back surface of the workpiece 1. The workpiece 1 is carried into the laser processing apparatus and processed in a state of a frame unit integrated with the tape 7 and the frame 9.

[0016] Tape 7 comprises a flexible film-like base material and an adhesive layer formed on one side of the base material. For example, PO (polyolefin) is used for the base material. Materials with higher rigidity than PO, such as PET (polyethylene terephthalate), polyvinyl chloride, or polystyrene, may also be used. For the adhesive layer, for example, silicone rubber, acrylic materials, epoxy materials, etc., may be used.

[0017] [Laser processing equipment] Next, we will describe a laser processing apparatus 2 according to one embodiment of the present invention.

[0018] Figure 2 is a schematic side view showing the configuration of the laser processing apparatus 2. The laser processing apparatus 2 comprises a holding table 6 for holding the workpiece 1 and a laser beam irradiation unit 8 disposed above the holding table 6. Prior to dividing the workpiece 1, the laser processing apparatus 2 irradiates the workpiece 1 with pulsed laser light along the planned processing line 3 of the workpiece 1 to form processing grooves and remove the functional layer including the interlayer insulating film using a low-k film.

[0019] The holding table 6 has a porous member 61 on its upper side and a suction source 62 connected to the porous member 61. The upper surface of the porous member 61 becomes a holding surface 6a for holding the workpiece 1. When the workpiece 1 is placed on the holding surface 6a and negative pressure generated by the suction source 62 is applied to the workpiece 1 through the holes in the porous member 61, the workpiece 1 is held in place by suction to the holding table 6. Clamps (not shown) for fixing the frame 9 are also provided around the holding table 6.

[0020] The holding table 6 is rotatable around an axis perpendicular to the holding surface 6a. Furthermore, the holding table 6 is configured so that the holding surface 6a can move horizontally (in the machining feed direction and the indexing feed direction) by a moving mechanism (not shown) including a motor and a ball screw.

[0021] The laser beam irradiation unit 8 includes a laser oscillator 38 that emits a laser beam, a mirror 42 that reflects the laser beam emitted by the laser oscillator 38 in a predetermined direction, and a focusing lens 50 that focuses the laser beam and irradiates the workpiece 1 held on the holding table 6.

[0022] The laser oscillator 38 has the function of emitting a laser beam with a wavelength that is absorbed by the workpiece 1. For example, a laser beam with a wavelength of 355 nm emitted using Nd:YAG or the like as a medium is used. When laser processing the workpiece 1, the laser beam is emitted under conditions such as a pulse width of 40 ns or less, a frequency of 100 kHz, and an output of 20 W or less. During processing, the workpiece 1 is irradiated with the laser beam under conditions such as a processing feed rate of 700 mm / s to 1000 mm / s and 3 or 4 irradiations per planned processing line 3.

[0023] The laser beam emitted by the laser oscillator 38 is reflected in a predetermined direction by the mirror 42, focused by the focusing lens 50, and irradiated onto the workpiece 1 held on the holding table 6.

[0024] When a laser beam is irradiated onto a workpiece 1 to form a processing groove and remove a functional layer containing a Low-k film, the functional layer may peel off from the workpiece 1. If the functional layer peels off from the workpiece 1, the quality of the device chip formed from the workpiece 1 may deteriorate. This is known to be due to the Gaussian distribution of the energy density of the laser beam irradiated along the planned processing line 3. In particular, the tail portion of the energy density distribution that becomes a Gaussian distribution is the cause of the peeling off of the functional layer.

[0025] Therefore, the laser beam irradiation unit 8 is disposed between the laser oscillator 38 and the focusing lens 50 and further includes a mask portion 44 that shields a part of the laser beam. The mask portion 44 functions as an energy distribution correction means that modifies the energy distribution by trimming off the tail portion of the Gaussian distribution. In the example shown in Figure 2, the mask portion 44 is disposed between the mirror 42 and the focusing lens 50, but it is not limited to this and may be disposed between the laser oscillator 38 and the mirror 42.

[0026] Figure 3(A) is a perspective view showing an example of the mask portion 44. The mask portion 44 shown in Figure 3(A) includes two base materials 52 made of materials such as stainless steel, ceramics, or quartz, a slit 54 formed between the two base materials 52, and reflective portions 56 provided on each base material 52.

[0027] Each substrate 52 is composed of a rectangular plate member. The slit 54 is formed as a gap between two substrates 52 and has a rectangular shape. The slit 54 restricts and shields the passage of a portion of the laser beam. The reflective portion 56 is, for example, composed of a reflective film provided on the incident surface (in this case, the top surface) of each substrate 52.

[0028] When the mask portion 44 is attached to the laser beam irradiation unit 8, the slits 54 of the mask portion 44 shown in Figure 3(A) are provided so that their width can be adjusted by changing the relative position of adjacent substrates 52. This makes it possible to adjust the width of the slits 54 without replacing the mask portion 44, thereby improving the convenience of the laser processing apparatus 2.

[0029] Figures 3(B) and 3(C) are schematic perspective views showing another example of the mask portion 44. The mask portion 44 shown in Figures 3(B) and 3(C) includes one base material 52, a slit 54 formed in the base material 52, and a reflective portion 56 provided on the upper surface of the base material 52 and surrounding the slit 54. In Figure 3(B), the base material 52 is composed of a rectangular plate member, and in Figure 3(C), the base material 52 is composed of a circular plate member.

[0030] When the laser beam enters the slit 54 of the mask portion 44, a portion of the Gaussian distribution of the laser beam's energy density, corresponding to the tail end, is shielded, thereby modifying the energy density distribution. Specifically, the tail end of the Gaussian distribution becomes a vertical distribution. As a result, the steep energy on both sides of the laser beam's energy density distribution is irradiated perpendicularly to the functional layer of the workpiece 1, so that the machining grooves formed on the workpiece 1 are formed with their outer edges perpendicular to the machining surface of the functional layer. Therefore, the peeling of the functional layer from the workpiece 1 can be suppressed.

[0031] Since the mask portion 44 is provided with a reflective portion 56, a portion of the laser beam is reflected by the reflective portion 56. If the mask portion 44 were not provided with a reflective portion 56, the base material 52 of the mask portion 44 would absorb a portion of the laser beam and generate heat. In addition, if the output of the laser beam is high, the base material 52 of the mask portion 44 may be damaged. In contrast, in this embodiment, because the mask portion 44 is provided with a reflective portion 56, a portion of the laser beam does not reach the base material 52, thereby suppressing the generation of heat in the base material 52 and preventing damage to the base material 52.

[0032] Furthermore, the mask portion 44 is positioned at an angle to prevent a portion of the laser beam from returning to the laser oscillator 38 after being reflected by the reflector portion 56. This prevents a portion of the laser beam reflected by the reflector portion 56 from traveling backward and returning to the laser oscillator 38, thereby avoiding damage to the laser oscillator 38 and instability in its operation.

[0033] Figure 4 is a side view of the mask section 44 installed in the optical path of a laser beam. The dashed arrows in the figure represent the reflected light reflected by the mask section 44.

[0034] The mask portion 44 is arranged such that, for example, the reflecting portion 56 is inclined with respect to a plane perpendicular to the direction of propagation of the laser beam passing through the slit 54. As a result, a portion of the laser beam incident on the reflecting portion 56 of the mask portion 44 is reflected in a direction different from the direction of propagation of the laser beam, thus preventing the reflected light from returning to the laser oscillator 38.

[0035] Incidentally, components positioned in the direction of reflected light propagation will generate heat at the light-receiving surface that receives the reflected light. If this heat is transferred to the laser beam's optical path, a mirage may occur in the laser beam's path. When a mirage occurs, fluctuations occur in the laser beam, making laser processing unstable.

[0036] Therefore, the laser beam irradiation unit 8 further includes a heat dissipation unit 45 that receives the reflected light reflected by the reflective portion 56 of the mask portion 44 and dissipates the heat generated by the reflected light. This suppresses the transfer of heat generated on the light-receiving surface that receives the reflected light into the optical path of the laser beam. As a result, the occurrence of mirages in the optical path of the laser beam can be suppressed, enabling stable laser processing.

[0037] Figure 5 is a schematic diagram showing an example of a heat dissipation unit 45. The heat dissipation unit 45 is a water-cooled type that dissipates heat generated by reflected light using a circulating liquid (e.g., cooling water).

[0038] Specifically, the heat dissipation unit 45 includes a light-receiving surface 70 that receives reflected light, a flow path 71 through which a liquid that cools the light-receiving surface 70 flows, and a pump 72 that circulates the liquid through the flow path 71. Preferably, at least a portion of the flow path 71 formed in the heat dissipation unit 45 is formed along the light-receiving surface 70 that receives reflected light. During laser processing by the laser beam irradiation unit 8, the heat dissipation unit 45 (pump 72) operates and liquid flows through the flow path 71.

[0039] The water-cooled heat dissipation unit 45 provides high heat dissipation performance, allowing sufficient heat generated on the light-receiving surface 70 due to reflected light to be dissipated.

[0040] Furthermore, if a flow path is provided in the laser oscillator 38, the flow path 71 in the heat dissipation section 45 and the flow path provided in the laser oscillator 38 may be in communication with each other. With this configuration, the liquid flowing through the laser oscillator 38 can be used for heat dissipation in the heat dissipation section 45, thus saving water.

[0041] Figure 6 is a schematic diagram showing another example of the heat dissipation unit 45. The heat dissipation unit 45 is air-cooled, for example, by exhausting the air around the light-receiving surface 70.

[0042] Specifically, the heat dissipation unit 45 includes a light-receiving surface 70 that receives reflected light, an intake fan 75 that draws in air from around the light-receiving surface 70, and an intake duct 77 that internally partitions an exhaust path 76 that guides the air from around the light-receiving surface 70 to the intake fan 75. The wall portion of the intake duct 77 that partitions the exhaust path 76, specifically the portion of the wall provided between the optical path of the laser beam incident on the mask unit 44 and the exhaust path 76, is also called a partition wall 77w. During laser processing by the laser beam irradiation unit 8, the heat dissipation unit 45 (intake fan 75) operates, and the air from around the light-receiving surface 70 is exhausted.

[0043] The air-cooled heat dissipation section 45 can also dissipate the heat generated on the light-receiving surface 70 by reflected light. Furthermore, since a partition wall 77w is provided between the laser beam path and the exhaust path 76, it is possible to suppress the flow of air heated on the light-receiving surface 70 into the laser beam path.

[0044] Figure 7 is a side view of the laser beam irradiation unit 8 of Modification 1. In the laser beam irradiation unit 8 of Modification 1, the mask portion 44 is provided with a portion 44a on one side of the slit 54 and a portion 44b on the other side, which are inclined in opposite directions. Specifically, portions 44a and 44b of the mask portion 44 are inclined downward toward the direction away from the slit 54 (outward direction). In addition, a reflective portion 56 is provided on the upper surface of portions 44a and 44b of the mask portion 44.

[0045] Figure 8 is a side view of the laser beam irradiation unit 8 of Modified Example 2. The portions 44a and 44b of the mask portion 44 of the laser beam irradiation unit 8 of Modified Example 2 are inclined upward toward the direction away from the slit 54. In addition, a reflective portion 56 is provided on the upper surface of portions 44a and 44b of the mask portion 44.

[0046] In Modification 1 and Modification 2, the reflected light reflected by the reflective portion 56 provided in portion 44a of the mask portion 44 and the reflected light reflected by the reflective portion 56 provided in portion 44b of the mask portion 44 travel in different directions. Two heat dissipation sections 45 are provided, one for each of the two directions in which the reflected light travels.

[0047] As described above, multiple heat dissipation sections 45 are provided, which allows for the dispersion of heat generated by reflected light. Therefore, the amount of heat generated at each individual light-receiving surface 70 is reduced, and the transfer of heat generated at the light-receiving surface 70 to the optical path of the laser beam can be further suppressed.

[0048] Note that the mask portion 44 in Modification 1 and Modification 2 is not limited to the mask portion 44 shown in Figure 3(A), but may also be the mask portion 44 shown in Figures 3(B) and (C). In the case of the mask portion 44 shown in Figures 3(B) and (C), the aforementioned portions 44a and 44b are formed by folding the mask portion 44 with respect to the long axis of the slit 54.

[0049] Furthermore, the mask portion 44 may be arranged so that the reflected light reflected by the reflective portion 56 travels in three or more directions. In such cases as well, multiple heat dissipation portions 45 are provided, corresponding to each of the multiple directions in which the reflected light travels.

[0050] [Laser processing method] Next, a laser processing method according to one embodiment of the present invention will be described. Here, a laser processing method performed using the laser processing apparatus 2 described above will be explained as an example.

[0051] Figure 9 is a flowchart of a laser processing method according to one embodiment of the present invention. The laser processing method comprises a holding step S1, a heat dissipation step S2, and a laser beam irradiation step S3.

[0052] The holding step S1 involves holding the workpiece 1 on the holding table 6. Specifically, the holding step S1 involves activating the suction source 62 to suction and hold the workpiece 1 on the holding table 6.

[0053] The heat dissipation step S2 activates the heat dissipation unit 45. In one example shown in Figure 5, the heat dissipation step S2 activates the pump 72 to circulate liquid through the flow path 71. In another example shown in Figure 6, the heat dissipation step S2 activates the intake fan 75 to exhaust the air around the light-receiving surface 70.

[0054] In the laser beam irradiation step S3, with the heat dissipation unit 45 activated, the laser beam irradiation unit 8 irradiates the workpiece 1 held on the holding table 6 with a laser beam. Specifically, in the laser beam irradiation step S3, the laser beam is irradiated onto the workpiece 1 via a mask unit 44 having a reflector 56 provided on the optical path of the laser beam, so that a portion of the laser beam is shielded by the mask unit 44.

[0055] Thus, the laser processing method of this embodiment can suppress the transfer of heat generated at the light-receiving surface 70 that receives reflected light into the optical path of the laser beam. As a result, the occurrence of mirages in the optical path of the laser beam can be suppressed, enabling stable laser processing.

[0056] Although one embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to this embodiment. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these are also understood to naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiment may be combined in any way without departing from the spirit of the invention.

[0057] For example, the laser beam irradiation unit 8 may further include a cylindrical lens. The cylindrical lens has the function of deforming the laser beam into an elliptical laser beam having its major axis in a direction perpendicular to the processing feed direction of the workpiece 1. The cylindrical lens may be disposed between the mask portion 44 and the focusing lens 50, or the mask portion 44 may be positioned between the cylindrical lens and the focusing lens 50.

[0058] This specification includes at least the following: The components and other elements corresponding to those in the embodiments described above are shown in parentheses as examples, but are not limited thereto.

[0059] (1) A holding table (holding table 6) that holds the workpiece (workpiece 1), A laser processing apparatus (laser processing apparatus 2) comprising a laser beam irradiation unit (laser beam irradiation unit 8) for irradiating a workpiece held on the holding table with a laser beam, The aforementioned laser beam irradiation unit is The laser oscillator (laser oscillator 38) that emits the aforementioned laser beam, A focusing lens (focusing lens 50) that focuses the laser beam and irradiates it onto the workpiece held on the holding table, It has a mask portion (mask portion 44) disposed between the laser oscillator and the focusing lens, which shields a portion of the laser beam, The mask portion has a reflective portion (reflective portion 56) that reflects the shielded laser beam, The laser beam irradiation unit further includes a heat dissipation unit (heat dissipation unit 45) that receives the reflected light reflected by the reflecting unit and dissipates the heat generated by the reflected light. Laser processing equipment.

[0060] According to (1), the mask portion has a reflective portion that reflects the shielded laser beam, so that heat generation in the mask portion due to the absorption of the laser beam can be suppressed. Furthermore, the laser beam irradiation unit has a heat dissipation portion that receives the reflected light reflected by the reflective portion and dissipates the heat generated by the reflected light, so that the heat generated by the reflected light can be suppressed from being transmitted to the optical path of the laser beam. As a result, the occurrence of mirages in the optical path of the laser beam can be suppressed, and stable laser processing can be performed.

[0061] (2) A laser processing apparatus as described in (1), The heat dissipation unit is water-cooled, having a flow path (flow path 71) through which liquid flows, and dissipating the heat generated by the reflected light using the liquid flowing through the flow path. Laser processing equipment.

[0062] According to (2), a water-cooled heat dissipation unit can achieve high heat dissipation performance.

[0063] (3) A laser processing apparatus as described in (2), The aforementioned laser oscillator is provided with a channel through which liquid flows. The flow path in the heat dissipation section and the flow path provided in the laser oscillator are in communication. Laser processing equipment.

[0064] According to (3), the liquid flowing through the laser oscillator can be used for heat dissipation in the heat dissipation section, thus saving water.

[0065] (4) A laser processing apparatus as described in (1), The heat dissipation unit is an air-cooled type that dissipates heat generated on the light-receiving surface (light-receiving surface 70) by exhausting the air surrounding the light-receiving surface (light-receiving surface 70) that receives the reflected light. A partition wall (partition wall 77w) is provided between the optical path of the laser beam incident on the mask portion and the exhaust path (exhaust path 76) of the air in the heat dissipation portion. Laser processing equipment.

[0066] According to (4), the air-cooled heat dissipation section can dissipate the heat generated on the light-receiving surface by reflected light. In addition, since a partition is provided between the optical path of the laser beam and the exhaust path, it is possible to suppress the air heated on the light-receiving surface from moving towards the optical path of the laser beam.

[0067] (5) A laser processing apparatus as described in any of (1) to (4), The reflective portion of the mask portion reflects the incident laser beam in multiple directions. The heat dissipation section is provided in multiple locations corresponding to each of the multiple directions in which the reflected light propagates. Laser processing equipment.

[0068] According to (5), since multiple heat dissipation sections are provided, the heat generated by reflected light can be dispersed. Therefore, the occurrence of mirages in the optical path of the laser beam can be further suppressed.

[0069] (6) A laser processing apparatus as described in any of (1) to (5), The mask portion comprises at least two substrates (substrate 52), a slit (slit 54) formed between adjacent substrates through which the laser beam passes, and the reflective portion formed on the substrate. The slits are provided so that their width can be adjusted by changing the relative positions of adjacent substrates. Laser processing equipment.

[0070] According to (6), the width of the slit can be adjusted without replacing the mask, thus improving the convenience of the laser processing device.

[0071] (7) A holding step (holding step S1) in which the workpiece (workpiece 1) is held on the holding table (holding table 6), A laser processing method comprising a laser beam irradiation step (laser beam irradiation step S3) of irradiating a workpiece held on the holding table with a laser beam, The laser beam irradiation step involves irradiating the workpiece with a laser beam through a mask portion (mask portion 44) having a reflective portion (reflective portion 56) provided on the optical path of the laser beam, such that a portion of the laser beam is shielded by the mask portion. The laser processing method further includes a heat dissipation step (heat dissipation step S2) which receives the reflected light reflected by the reflecting part and activates a heat dissipation part (heat dissipation part 45) that dissipates the heat generated by the reflected light. Laser processing method.

[0072] According to (7), the laser beam irradiation step irradiates the workpiece with a laser beam through a mask having a reflective section, thus suppressing heat generation in the mask due to the absorption of the laser beam. Furthermore, the laser processing method includes a heat dissipation step that activates a heat dissipation section to dissipate heat generated by reflected light, thus suppressing the transfer of heat generated by reflected light into the optical path of the laser beam. As a result, the occurrence of mirages in the optical path of the laser beam can be suppressed, enabling stable laser processing. [Explanation of symbols]

[0073] 1 Workpiece 2. Laser processing equipment 6. Holding Table 8. Laser beam irradiation unit 38 Laser Oscillator 44 Mask section 45 Heat dissipation section 50 Focusing Lens 52 Base material 54 slits 56 Reflector 70 Photosensitive surface 71 Flow channels 76 Exhaust path 77w bulkhead S1 Holding step S2 Heat Dissipation Step S3 Laser beam irradiation step

Claims

1. A holding table for holding the workpiece, A laser processing apparatus comprising: a laser beam irradiation unit that irradiates a workpiece held on the holding table with a laser beam; The aforementioned laser beam irradiation unit is A laser oscillator that emits the aforementioned laser beam, A focusing lens that focuses the laser beam and irradiates it onto the workpiece held on the holding table, It has a mask portion disposed between the laser oscillator and the focusing lens, which shields a portion of the laser beam, The mask portion has a reflective portion that reflects the shielded laser beam, The laser beam irradiation unit further includes a heat dissipation unit that receives the reflected light reflected by the reflecting unit and dissipates the heat generated by the reflected light. Laser processing equipment.

2. A laser processing apparatus according to claim 1, The heat dissipation unit is water-cooled, having a flow path through which a liquid flows, and the heat generated by the reflected light is dissipated by the liquid flowing through the flow path. Laser processing equipment.

3. A laser processing apparatus according to claim 2, The aforementioned laser oscillator is provided with a channel through which liquid flows. The flow path in the heat dissipation section and the flow path provided in the laser oscillator are in communication. Laser processing equipment.

4. A laser processing apparatus according to claim 1, The heat dissipation unit is air-cooled, which exhausts the air surrounding the light-receiving surface that receives the reflected light, thereby dissipating the heat generated on the light-receiving surface. A partition wall is provided between the optical path of the laser beam incident on the mask portion and the exhaust path of the air in the heat dissipation portion. Laser processing equipment.

5. A laser processing apparatus according to any one of claims 1 to 4, The reflective portion of the mask portion reflects the incident laser beam in multiple directions. The heat dissipation section is provided in multiple locations corresponding to each of the multiple directions in which the reflected light propagates. Laser processing equipment.

6. A laser processing apparatus according to any one of claims 1 to 4, The mask portion comprises at least two substrates, a slit formed between adjacent substrates through which the laser beam passes, and the reflective portion formed on the substrate. The slits are provided so that their width can be adjusted by changing the relative positions of adjacent substrates. Laser processing equipment.

7. A holding step in which the workpiece is held on a holding table, A laser processing method comprising: a laser beam irradiation step of irradiating a workpiece held on the holding table with a laser beam, The laser beam irradiation step involves irradiating the workpiece with a laser beam through a mask portion having a reflective portion provided on the optical path of the laser beam, such that a portion of the laser beam is shielded by the mask portion. The laser processing method further comprises a heat dissipation step of receiving reflected light reflected by the reflecting part and activating a heat dissipation part that dissipates the heat generated by the reflected light. Laser processing method.

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