Laser processing device

Abstract

To provide a laser processing device which can suppress deviation in a processing position.SOLUTION: A laser processing device 1 includes an oscillator 23 for generating a laser beam 21 which is condensed on a workpiece 200 held by a holding unit and is emitted, and a scanning unit 24 for scanning the workpiece 200 with the laser beam 21 in an X direction perpendicular to a Y direction. The scanning unit 24 has a scanner 27 for scanning the workpiece with the laser beam 21 generated by the oscillator 23 in the X direction, a first lens 28 for making the laser beam 21 from the scanner 27 incident thereon, and making the laser beam 21 vertical to the workpiece 200, and a second lens 29 for condensing the laser beam 21 emitted from the first lens 28 in the Y direction, and the lengths in the X direction of the first lens 28 and the second lens 29 are set to be equal to or longer than the length in the X direction of the workpiece 200 held by the holding unit.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a laser processing apparatus. [Background technology]

[0002] A processing device is widely used that performs laser processing on a workpiece by focusing and irradiating a laser beam onto the workpiece while moving a holding unit that holds the workpiece relative to the laser beam in the processing feed direction and index feed direction using a moving mechanism (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-031871 A Summary of the Invention [Problem to be solved by the invention]

[0004] An axis unit using a ball screw or a linear motor is used in the movement mechanism of the processing device shown in Patent Document 1. Frictional heat generated by the movement of the processing feed causes thermal expansion of the axis unit and the periphery of the focusing lens holder, which may cause the processing position (position of the focal point of the laser beam) to deviate from the desired position, so the processing position is appropriately corrected, and further improvement is desired.

[0005] An object of the present invention is to provide a laser processing apparatus capable of suppressing deviation of the processing position. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, a laser processing apparatus of the present invention is a laser processing apparatus comprising: a holding unit for holding a workpiece; a light source for generating a laser beam which is focused and irradiated onto the workpiece held by the holding unit; an index feed unit for moving the holding unit holding the workpiece in a Y direction relative to a focusing point of the laser beam; and a scanning unit for scanning the laser beam generated by the light source in an X direction perpendicular to the Y direction with respect to the workpiece held by the holding unit, the scanning unit comprising: a scanner for scanning the laser beam generated by the light source in the X direction; a first lens having a curvature in the X direction that makes the laser beam perpendicular to the workpiece held by the holding unit when the laser beam from the scanner is incident thereon; and a second lens having a curvature in the Y direction that focuses the laser beam emitted from the first lens in the Y direction, the first lens and the second lens each having a length in the X direction set to be greater than or equal to the length in the X direction of the workpiece held by the holding unit.

[0007] In the laser processing apparatus, the scanner may be a polygon scanner having a plurality of mirrors that reflect the laser beam generated by the light source.

[0008] The laser processing apparatus may further include a liquid supply unit disposed between the second lens and the holding unit for supplying liquid to at least the area on the upper surface of the workpiece held by the holding unit where the laser beam is irradiated, and the liquid supply unit may include a transmission window that transmits the laser beam focused by the second lens, and a liquid supply section having a liquid outlet formed adjacent to the transmission window in the Y direction. Effect of the Invention

[0009] The present invention has an effect of suppressing deviation of the processing position. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1 is a perspective view illustrating a configuration example of a laser processing apparatus according to the first embodiment. [Diagram 2] FIG. 2 is a perspective view diagrammatically showing a wafer to be processed by the laser processing apparatus according to the first embodiment. [Diagram 3] 3 is another perspective view of the laser processing apparatus shown in FIG. 1. FIG. [Figure 4] FIG. 4 is a perspective view illustrating a schematic configuration of a laser beam irradiation unit of the laser processing apparatus illustrated in FIG. [Diagram 5] FIG. 5 is a perspective view diagrammatically illustrating a first lens and the like of the laser beam irradiation unit shown in FIG. [Figure 6] FIG. 6 is a perspective view illustrating a schematic view of the second lens and the like of the laser beam irradiation unit illustrated in FIG. [Figure 7] FIG. 7 is a perspective view illustrating a configuration example of a laser processing apparatus according to the second embodiment. [Figure 8] FIG. 8 is another perspective view of the laser processing apparatus shown in FIG. [Figure 9] FIG. 9 is a side view, partially in cross section, showing a schematic configuration of a liquid supply unit and the like of the laser processing apparatus shown in FIG. [Figure 10] FIG. 10 is a plan view of the liquid supply unit shown in FIG. 9, viewed from below. [Figure 11] FIG. 11 is a side view, partially in section, showing a schematic diagram of the laser processing apparatus shown in FIG. 7 during over-processing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The form (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0012] [Embodiment 1] A laser processing device according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a typical configuration example of the laser processing device according to the first embodiment. Fig. 2 is a perspective view showing a typical wafer to be processed by the laser processing device according to the first embodiment. Fig. 3 is another perspective view of the laser processing device shown in Fig. 1.

[0013] (workpiece) The laser processing apparatus 1 according to the embodiment shown in Fig. 1 is a processing apparatus for processing a workpiece 200 shown in Fig. 2. The workpiece 200 to be processed by the laser processing apparatus 1 according to the embodiment is a disk-shaped semiconductor wafer, an optical device wafer, or the like, with a substrate 201 made of silicon (Si), gallium arsenide (GaAs), silicon carbide (SiC), sapphire, or the like.

[0014] 2, the workpiece 200 has devices 204 formed in each of the regions defined by a plurality of planned division lines 203 on the surface 202. The devices 204 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integration), image sensors such as CCDs (Charge Coupled Devices) or CMOSs ​​(Complementary Metal Oxide Semiconductors), optical elements such as LEDs (Light-Emitting Diodes), MEMS (Micro Electro Mechanical Systems), or semiconductor memories (semiconductor storage devices).

[0015] The workpiece 200 is divided into individual chips 210 along the planned division lines 203. The chips 210 include a part of the substrate 201 and a device 204. In the first embodiment, the workpiece 200 is divided into individual chips 210 by the laser processing device 1 shown in FIG. 1 after an adhesive tape 211 having an annular frame 212 attached to its outer edge is attached to the back surface 205 on the back side of the front surface 202 as shown in FIG. 2. The adhesive tape 211 may be an adhesive tape having a base material made of a resin having non-adhesive properties and flexibility, and a glue layer made of a resin having adhesive properties and flexibility laminated on the base material, and the glue layer may be attached to the annular frame 212 and the workpiece 200, or may be a so-called glueless tape made of only a base material made of a non-adhesive thermoplastic resin and heat-pressed to the annular frame 212 and the workpiece 200.

[0016] (Laser processing equipment) The laser processing apparatus 1 according to the first embodiment is a processing apparatus that divides a workpiece 200, on which a plurality of planned division lines 203 are formed, along the planned division lines 203 to manufacture a plurality of chips 210. The laser processing apparatus 1 according to the first embodiment is a processing apparatus that performs laser processing (also called ablation processing) on ​​the workpiece 200 by setting a focal point 22 of a pulsed laser beam 21 having a wavelength absorbed by a substrate 201 constituting the workpiece 200, on a surface 202 of the substrate 201, and irradiating the laser beam 21 from the surface 202 of the workpiece 200 along the planned division lines 203.

[0017] As shown in FIG. 1, the laser processing apparatus 1 includes a holding unit 10 that holds a workpiece 200, a laser beam irradiation unit 20, a moving unit 40, an imaging unit 50, and a control unit 100.

[0018] The holding unit 10 holds the workpiece 200 on a holding surface 11 parallel to the horizontal direction. The holding surface 11 is disk-shaped and made of porous ceramic, quartz, or the like, and has a suction port that opens on the surface and is connected to a vacuum suction source (not shown) via a suction path (not shown). The holding unit 10 suction-holds the workpiece 200 placed on the holding surface 11 by being sucked by the vacuum suction source. A plurality of clamps 12 are arranged around the holding unit 10 to clamp an annular frame 212 that supports the workpiece 200 in the opening.

[0019] The holding unit 10 is rotated by the rotational movement unit 43 of the movement unit 40 about an axis parallel to the Z direction perpendicular to the holding surface 11 and parallel to the vertical direction. The holding unit 10 is moved together with the rotational movement unit 43 in the X direction (corresponding to the processing proceeding direction) parallel to the horizontal direction by the X-axis movement unit 41 of the movement unit 40, and is moved in the Y direction parallel to the horizontal direction and perpendicular to the X direction by the Y-axis movement unit 42. The holding unit 10 is moved by the movement unit 40 across a processing area below the laser beam irradiation unit 20 and a carry-in / out area away from below the laser beam irradiation unit 20 where the workpiece 200 is carried in and out.

[0020] The moving unit 40 relatively moves the holding unit 10 and the focal point 22 of the laser beam 21 irradiated by the laser beam irradiation unit 20 around axes parallel to the X, Y, and Z directions. The X and Y directions are perpendicular to each other and parallel to the holding surface 11 (i.e., the horizontal direction). The Z direction is perpendicular to both the X and Y directions.

[0021] The moving unit 40 includes an X-axis moving unit 41 which is a processing feed unit that moves the holding unit 10 in the X direction, a Y-axis moving unit 42 which is an index feed unit that moves the holding unit 10 in the Y direction, and a rotational moving unit 43 which rotates the holding unit 10 around an axis parallel to the Z direction.

[0022] The Y-axis moving unit 42 is an index feed unit that moves the holding unit 10 holding the workpiece 200 in the Y direction relatively to the focal point 22 of the laser beam 21 of the laser beam irradiation unit 20. In the first embodiment, the Y-axis moving unit 42 is installed on the device body 2 of the laser processing device 1. The Y-axis moving unit 42 supports the moving plate 4 supporting the X-axis moving unit 41 so as to be freely movable in the Y direction.

[0023] The X-axis moving unit 41 is a processing feed unit that moves the holding unit 10 in the X direction relatively to the focal point 22 of the laser beam 21 of the laser beam irradiation unit 20. The X-axis moving unit 41 is installed on the moving plate 4. The X-axis moving unit 41 supports a second moving plate 5 that supports a rotational moving unit 43 that rotates the holding unit 10 around an axis parallel to the Z direction, so as to be movable in the X direction. The second moving plate 5 supports the rotational moving unit 43 and the holding unit 10. The rotational moving unit 43 supports the holding unit 10.

[0024] The X-axis moving unit 41 includes a well-known ball screw that is rotatable about its axis and moves the second moving plate 5 in the X direction when rotated about its axis, a well-known pulse motor that rotates the ball screw about its axis, and a well-known guide rail that supports the second moving plate 5 movably in the X direction. The Y-axis moving unit 42 includes a well-known ball screw that is rotatable about its axis and moves the moving plate 4 in the Y direction when rotated about its axis, a well-known pulse motor that rotates the ball screw about its axis, and a well-known guide rail that supports the moving plate 4 movably in the Y direction. The rotation moving unit 43 includes a motor that rotates the holding unit 10 about its axis, etc.

[0025] In the laser processing apparatus 1 of the first embodiment, as shown in FIG. 3, the X-axis moving unit 41 is covered by an X-axis moving unit protective bellows 44 attached to the apparatus body 2 and the second moving plate 5, and the Y-axis moving unit 42 is covered by a Y-axis moving unit protective bellows 45 attached to the apparatus body 2.

[0026] The laser processing apparatus 1 also includes an X-direction position detection unit (not shown) for detecting the position of the holding unit 10 in the X direction, a Y-direction position detection unit (not shown) for detecting the position of the holding unit 10 in the Y direction, and a Z-direction position detection unit (not shown) for detecting the position of the focusing lens of the laser beam irradiation unit 20 in the Z direction. Each position detection unit outputs the detection result to the control unit 100. In the first embodiment, the position of the holding unit 10 of the laser processing apparatus 1 in the X direction, the Y direction, and the position of the focusing lens of the laser beam irradiation unit 20 in the Z direction are determined by the distances in the X direction, Y direction, and Z direction from a predetermined reference position (not shown), etc.

[0027] The laser beam irradiation unit 20 is a laser beam irradiation means for concentrating and irradiating a pulsed laser beam 21 onto the workpiece 200 held on the holding surface 11 of the holding unit 10. In the first embodiment, a part of the laser beam irradiation unit 20 is disposed at the tip of a support column 6 supported by an erect wall 3 erected from the apparatus main body 2, as shown in Figs. 1 and 3. The configuration of the laser beam irradiation unit 20 will be described later.

[0028] The imaging unit 50 captures an image of the workpiece 200 held by the holding unit 10. The imaging unit 50 includes an imaging element such as a CCD (Charge Coupled Device) imaging element or a CMOS (Complementary MOS) imaging element that captures an image of an object facing the objective lens in the Z direction. In the first embodiment, the imaging unit 50 is disposed at the tip of the support column 6 as shown in FIG.

[0029] The imaging unit 50 acquires an image captured by the imaging element, and outputs the acquired image to the control unit 100. The imaging unit 50 also acquires an image of the workpiece 200 held on the holding surface 11 of the holding unit 10, and acquires an image for performing alignment for aligning the workpiece 200 with the laser beam irradiation unit 20.

[0030] The control unit 100 controls each of the above-mentioned components of the laser processing apparatus 1, and causes the laser processing apparatus 1 to perform a processing operation on the workpiece 200. The control unit 100 is a computer having an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input / output interface device. The arithmetic processing device of the control unit 100 performs arithmetic processing according to a computer program stored in the storage device, and outputs control signals for controlling the laser processing apparatus 1 to the above-mentioned components of the laser processing apparatus 1 via the input / output interface device, thereby realizing the functions of the control unit 100.

[0031] The laser processing device 1 also includes a display unit, which is a display means configured with a liquid crystal display device or the like for displaying the status of the processing operation, images, etc., and an input unit, which is an input means used when an operator inputs processing conditions, etc. The display unit and the input unit are connected to the control unit. In the first embodiment, the input unit is configured with a touch panel provided on the display unit.

[0032] Next, the configuration of the laser beam irradiation unit 20 will be described. Fig. 4 is a perspective view showing a schematic configuration of the laser beam irradiation unit of the laser processing apparatus shown in Fig. 1. Fig. 5 is a perspective view showing a schematic first lens, etc. of the laser beam irradiation unit shown in Fig. 4. Fig. 6 is a perspective view showing a schematic second lens, etc. of the laser beam irradiation unit shown in Fig. 4.

[0033] As shown in Fig. 4, the laser beam irradiation unit 20 includes an oscillator 23, which is a light source, and a scanning unit 24. The oscillator 23 generates a laser beam 21 that is focused and irradiated onto the workpiece 200 held by the holding unit 10. The oscillator 23 generates and emits the laser beam 21 having a predetermined wavelength for processing the workpiece 200. In addition, in the first embodiment, the laser beam irradiation unit 20 includes a mirror 25 that reflects the laser beam 21 emitted by the oscillator 23 toward a scanner 27 of the scanning unit 24, as shown in Fig. 4.

[0034] The scanning unit 24 scans the laser beam 21 generated and emitted by the oscillator 23 with respect to the workpiece 200 held by the holding unit 10 in an X direction perpendicular to the Y direction, and focuses and irradiates the laser beam 21 over the entire length of the planned dividing line 203 of the workpiece 200. As shown in Fig. 4, the scanning unit 24 includes a housing 26 (shown in Figs. 1 and 3), a scanner 27, a first lens 28, and a second lens 29.

[0035] Housing 26 is disposed at the tip of support column 6, and is a case that houses scanner 27, first lens 28, and second lens 29. Housing 26 has an opening formed in the lower part to expose second lens 29 downward.

[0036] The scanner 27 scans the laser beam 21 generated and emitted by the oscillator 23 in the X direction. In the first embodiment, the scanner 27 is a polygon scanner having a plurality of mirrors 271 that reflect the laser beam 21 generated and emitted by the oscillator 23. The scanner 27 is supported rotatably around a rotation axis 272 parallel to the Y direction, and a plurality of flat mirrors 271 are provided in the circumferential direction of the rotation axis 272. The scanner 27 rotates around the rotation axis 272 to change the mirror 25 that reflects the laser beam 21 and the orientation of the mirror 25 as shown in FIG. 5, thereby scanning the laser beam 21 generated and emitted by the oscillator 23 in the X direction.

[0037] The first lens 28 has a curvature in the X direction that makes the laser beam 21 incident from the scanner 27 perpendicular to the workpiece 200 held by the holding unit 10. The first lens 28 is made of a light-guiding material, is a cylindrical lens whose longitudinal direction is parallel to the X direction, and has a length in the X direction set to be equal to or greater than the length in the X direction of the workpiece 200 held by the holding unit 10 (outer diameter in the first embodiment). The first lens 28 has a width in the Y direction set to be less than the length in the Y direction of the workpiece 200 held by the holding unit 10 (outer diameter in the first embodiment).

[0038] The first lens 28 receives the laser beam 21 from the scanner 27 through an entrance surface 281, and emits the laser beam 21 from an exit surface 282 curved with respect to the X direction in a front view in which the X direction is the left-right direction, as shown in Fig. 5, thereby making the optical axis of the emitted laser beam 21 parallel to the Z direction and perpendicular to the workpiece 200 held by the holding unit 10. In this way, the first lens 28 has a curvature in the X direction such that the exit surface 282 makes the laser beam 21 perpendicular to the workpiece 200 held by the holding unit 10.

[0039] The second lens 29 has a curvature in the Y direction that focuses the laser beam 21 emitted from the first lens 28 in the Y direction. The second lens 29 is made of a light-guiding material, is a cylindrical lens whose longitudinal direction is parallel to the X direction, and has a length in the X direction set to be equal to or greater than the length in the X direction of the workpiece 200 held by the holding unit 10 (outer diameter in the first embodiment). The width in the Y direction of the second lens 29 is set to be less than the length in the Y direction of the workpiece 200 held by the holding unit 10 (outer diameter in the first embodiment).

[0040] 6, the second lens 29 receives the laser beam 21 from the first lens 28 through an entrance surface 291 curved with respect to the Y direction in a front view with the Y direction as the left-right direction, and emits the laser beam 21 from an exit surface 292 that is flat parallel to the X and Y directions, thereby concentrating the emitted laser beam 21 in the Y direction but not in the X direction, and irradiates the workpiece 200 held by the holding unit 10. For this reason, the focal point 22 of the laser beam 21 focused by the second lens 29, i.e., the scanning unit 24, is formed into an elliptical shape with the major axis parallel to the X direction.

[0041] In this way, the second lens 29 has a curvature in the Y direction that focuses the laser beam 21 in the Y direction. In the first embodiment, the second lens 29 is located below the first lens 28, with the entrance surface 291 curved with respect to the Y direction positioned above and the flat exit surface 292 positioned below. In this way, the curved exit surface 282 of the first lens 28 of the scanning unit 24 and the curved entrance surface 291 of the second lens 29 face each other. In the present invention, the orientation of the lenses 28 and 29 is not limited to that described in the first embodiment, and may be the opposite of that in the first embodiment.

[0042] Next, a processing operation of the laser processing device 1 according to the embodiment 1 will be described. In the embodiment 1, the control unit 100 of the laser processing device 1 receives and registers processing conditions and the like input by an operator, and the workpiece 200 is placed on the holding surface 11 of the holding unit 10 positioned in the carry-in / out area. In the embodiment 1, when the control unit 100 receives an instruction to start the processing operation from the operator, the laser processing device 1 suction-holds the workpiece 200 on the holding surface 11 of the holding unit 10 via the adhesive tape 211, and clamps the annular frame 212 with the clamp section 12.

[0043] In the first embodiment, the control unit 100 of the laser processing apparatus 1 controls the moving unit 40 to move the holding unit 10 to the processing area, and the imaging unit 50 captures an image of the workpiece 200 held by the holding unit 10 to perform alignment. In the first embodiment, the laser processing apparatus 1 sets the focal point 22 of the laser beam 21 on the surface 202 of the substrate 201 based on the processing conditions, positions the laser beam irradiation unit 20 above one of the planned division lines 203 of the workpiece 200 held by the holding unit 10 by the moving unit 40, reflects the laser beam 21 generated and emitted by the oscillator 23 on the mirror 271 of the scanner 27 around the rotation axis 272, makes the optical axis of the laser beam 21 parallel to the Z direction by the first lens 28, and focuses the laser beam 21 in the Y direction by the second lens 29 to scan the planned division line 203. In embodiment 1, the laser processing apparatus 1 scans the focused laser beam 21 along the planned division line 203 without moving the holding unit 10 in the X-axis direction with the X-axis moving unit 41, and irradiates the pulsed laser beam 21 from the surface 202 side of the substrate 201 along the entire length of the planned division line 203 of the workpiece 200, thereby ablation processing the substrate 201 of the workpiece 200 along the planned division line 203.

[0044] In the first embodiment, when the irradiation of one of the division lines 203 with the laser beam 21 is completed, the control unit 100 stops the emission of the laser beam 21 from the oscillator 23, controls the Y-axis moving unit 42 to position the laser beam irradiating unit 20 above the other division lines 203 of the workpiece 200 held by the holding unit 10, emits the laser beam 21 from the oscillator 23, and irradiates the laser beam 21 over the entire length of the division lines 203 by scanning with the scanner 27 without moving the holding unit 10 in the X-axis direction with the X-axis moving unit 41. Thus, in the first embodiment, the laser processing device 1 irradiates the laser beam 21 over the entire length of all the division lines 203 without moving the holding unit 10 in the X-axis direction with the X-axis moving unit 41, thereby dividing the workpiece 200 into individual chips 210. In addition, when the laser processing apparatus 1 irradiates the laser beam 21 onto each planned division line 203, the control unit 100 adjusts the rotation speed of the scanner 27 and the repetition frequency of the pulsed laser beam 21 generated by the oscillator 23 to appropriately adjust the overlap rate of the laser beam 21 irradiated onto the workpiece 200.

[0045] In embodiment 1, when the laser processing apparatus 1 irradiates all of the planned division lines 203 with the laser beam 21, it stops irradiating the laser beam 21, and the control unit 100 controls the moving unit 40 to move the holding unit 10 to the loading / unloading area, stops suction holding of the workpiece 200 by the holding unit 10, and releases the clamping of the annular frame 212 of the clamp section 12.

[0046] The laser processing apparatus 1 according to the embodiment 1 described above includes a scanning unit 24 that scans the laser beam generated by the oscillator 23 in the X direction, which is the processing feed direction, on the workpiece held by the holding unit 10. Moreover, in the laser processing apparatus 1 according to the embodiment 1, the first lens 28 and the second lens 29 of the scanning unit 24 are set to be equal to or greater than the length of the workpiece 200 in the X direction.

[0047] For this reason, the laser processing apparatus 1 according to the first embodiment can irradiate the workpiece 200 with the laser beam 21 over the entire length of each of the planned division lines 203 without moving the holding unit 10 by the X-axis moving unit 41 during processing feed, which generally has a high moving speed. As a result, the laser processing apparatus 1 according to the first embodiment has the effect of suppressing thermal expansion during processing and suppressing deviation of the processing position, which is the position of the focal point 22 of the laser beam 21.

[0048] Furthermore, in the laser processing apparatus 1 according to the first embodiment, the exit surface 282 having the larger curvature of the first lens 28 of the scanning unit 24 faces the curved entrance surface 291 of the second lens 29, so that aberration can be reduced.

[0049] In addition, in the laser processing apparatus 1 according to the first embodiment, the focal point 22 of the laser beam 21 is formed in an elliptical shape with the major axis parallel to the X-direction, and therefore the taper of the side of the laser processed groove formed in the processing progress direction in the X-direction is more gentle than that of the laser beam 21 with the circular focal point 22. As a result, the scattering direction of the debris becomes farther away from the processing point (the point where the laser beam 21 is irradiated onto the workpiece 200), and the laser processed groove is prevented from being backfilled with debris.

[0050] [Embodiment 2] A laser processing apparatus 1 according to the second embodiment will be described with reference to the drawings. FIG. 7 is a perspective view showing a typical configuration example of the laser processing apparatus according to the second embodiment. FIG. 8 is another perspective view of the laser processing apparatus shown in FIG. 7. FIG. 9 is a side view showing a typical configuration of a liquid supply unit and the like of the laser processing apparatus shown in FIG. 7, partially in cross section. FIG. 10 is a plan view of the liquid supply unit shown in FIG. 9, seen from below. FIG. 11 is a side view showing a typical state during over-processing of the laser processing apparatus shown in FIG. 7, partially in cross section. Note that in FIGS. 7, 8, 9, 10 and 11, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

[0051] 7, 8, 9, and 10, a laser processing apparatus 1-2 according to the second embodiment is the same as that of the first embodiment, except that it includes a liquid supply unit 30. The liquid supply unit 30 is disposed between the second lens 29 and the holding unit 10, and supplies liquid (e.g., pure water) to at least an area on the surface 202, which is the upper surface of the workpiece 200 held by the holding unit 10, where the laser beam 21 is irradiated.

[0052] The liquid supply unit 30 includes a unit body 31 formed in the shape of a thick flat plate attached to the lower end of the housing 26 of the scanning unit 24 of the laser beam irradiation unit 20, a transmission window 32 provided at a position facing the second lens 29 in the Z direction, and a liquid supply part 33. As shown in Fig. 9, the unit body 31 has an opening 34 penetrating it at a position facing the second lens 29 in the Z direction, through which the laser beam 21 focused by the second lens 29 passes.

[0053] The transmission window 32 is made of a light guiding material, is fitted in the opening 34, and transmits the laser beam 21 focused by the second lens 29. The lower surface 311 of the unit body 31 and the lower surface 321 of the transmission window 32 are formed flat along the horizontal direction, and the lower surface 321 of the transmission window 32 is disposed approximately 1 mm or less (e.g., several hundred μm) below the lower surface 311 of the unit body 31. The lower surface 321 of the transmission window 32 is disposed 0.5 mm or more and 1.0 mm or less above the surface 202 of the workpiece 200 held by the holding unit 10.

[0054] The liquid supply unit 33 includes a liquid injection port 35, a flow path 36, an on-off valve 37, and a liquid supply source 38. The liquid injection port 35 opens on the lower surface 311 of the unit body 31, and is connected to the liquid supply source 38 via the flow path 36 and the on-off valve 37 provided in the unit body 31. The liquid injection port 35 is disposed next to the transmission window 32 in the Y direction, that is, formed adjacent to the transmission window 32 in the Y direction. In the second embodiment, the liquid injection ports 35 are arranged in a plurality in the X direction, as shown in FIG. 10. The flow path 36 is inclined with respect to the Z direction and the Y direction in a direction gradually approaching the transmission window 32 as it approaches the liquid injection port 35.

[0055] When the laser processing apparatus 1-2 according to the second embodiment irradiates the planned division line 203 with the laser beam 21, as shown in Fig. 11, it opens the on-off valve 37 to supply liquid from the liquid supply source 38 from the liquid jet nozzle 35 to between the liquid supply unit 30 and the area of ​​the surface 202 of the workpiece 200 that is irradiated with the laser beam 21. Then, the flow path 36 is inclined as described above, and a predetermined flow rate is ejected from the liquid jet nozzle 35 to form a flow of liquid in the Y direction as shown by the arrow in Fig. 11, and the liquid is filled between the liquid supply unit 30 and the area of ​​the surface 202 of the workpiece 200 that is irradiated with the laser beam 21.

[0056] The laser processing apparatus 1-2 according to the second embodiment includes a scanning unit 24 that scans the laser beam generated by the oscillator 23 in the X-direction, which is the processing feed direction, on the workpiece held by the holding unit 10, and the first lens 28 and the second lens 29 are set to be equal to or longer than the length of the workpiece 200 in the X-direction. As a result, the laser processing apparatus 1-2 according to the second embodiment can irradiate the laser beam 21 onto the workpiece 200 over the entire length of each of the planned division lines 203 without moving the holding unit 10 by the X-axis moving unit 41, and has an effect of suppressing deviation of the processing position, which is the position of the focal point 22 of the laser beam 21.

[0057] In addition, in the laser processing apparatus 1-2 according to embodiment 2, the laser beam 21 is irradiated onto the workpiece 200 while the space between the surface 202 of the workpiece 200 and the lower surface 321 of the transmission window 32 is filled with liquid, thereby reducing damage to the workpiece 200 caused by heat generated during processing.

[0058] In addition, the laser processing apparatus 1-2 according to the second embodiment performs ablation processing while supplying liquid to the area of ​​the workpiece 200 that is irradiated with the laser beam 21, so that debris generated by the ablation processing can be efficiently removed from above the workpiece 200.

[0059] In addition, in the laser processing apparatus 1-2 according to the second embodiment, when the laser beam 21 is irradiated, air bubbles are generated in the liquid, and when the laser beam 21 is irradiated onto the generated air bubbles, the irradiated laser beam 21 is scattered by the air bubbles and is focused on an unintended area, resulting in the formation of processing marks.

[0060] However, the laser processing apparatus 1-2 of embodiment 2 can remove air bubbles from near the irradiation area of ​​the laser beam 21 by ejecting liquid from the liquid injection port 35 toward the transmission window 32 from next to the transmission window 32 in the Y direction, thereby causing the air bubbles to flow out.

[0061] Furthermore, in laser processing apparatus 1-2 according to embodiment 2, lower surface 321 of transmission window 32 protrudes slightly from lower surface 311 of liquid supply unit 30, so that lower surface 311 of liquid supply unit 30 outside transmission window 32 is positioned higher than lower surface 321 of transmission window 32, forming a step. As a result, in the event that air bubbles adhere to lower surface 321 of transmission window 32, laser processing apparatus 1-2 according to embodiment 2 can reduce the risk that the adhered air bubbles will move toward lower surface 311 of liquid supply unit 30 and laser beam 21 will be irradiated onto the air bubbles.

[0062] In addition, in the laser processing apparatus 1-2 according to the second embodiment, the focal point 22 of the laser beam 21 is formed in an elliptical shape with the major axis parallel to the X-direction, and the laser beam 21 is irradiated to the workpiece 200 in a state in which the space between the surface 202 of the workpiece 200 and the lower surface 321 of the transmission window 32 is filled with liquid. Therefore, when forming a laser processed groove of the same groove width, the area of ​​the focal point 22 is larger than that in the case of irradiating the laser beam 21 having a circular focal point 22, and the energy density is reduced. Therefore, even if the laser beam 21 is irradiated to an air bubble and scattered light is generated, damage due to the scattered light is unlikely to occur (i.e., the workpiece 200 is unlikely to be processed).

[0063] The present invention is not limited to the above-mentioned embodiment. In other words, various modifications can be made without departing from the gist of the present invention. For example, in the present invention, the oscillator 23 generates and emits the laser beam 21 having a wavelength that is transparent to the substrate 201 of the workpiece 200, and the laser processing device 1, 1-2 may form a modified layer along the planned division line 203 inside the substrate 201 of the workpiece 200. The modified layer means a region in which the density, refractive index, mechanical strength, and other physical properties are different from those of the surroundings, and examples of the modified layer include a melting process region, a crack region, an insulation breakdown region, a refractive index change region, and a region in which these regions are mixed. The modified layer has a lower mechanical strength than other parts of the substrate 201.

[0064] Furthermore, in the present invention, the first lens 28 and the second lens 29 of the laser processing device 1 are not limited to cylindrical lenses, and may be toroidal lenses. [Explanation of symbols]

[0065] 1,1-2 Laser processing equipment 10 Holding Unit 21 Laser Beam 22 Focus point 23 Oscillator (light source) 24 Scanning Unit 27 Scanner 28 First Lens 29 Second lens 30 Liquid Supply Unit 32 Transparent Windows 33 Liquid supply section 35 Liquid injection port 42 Y-axis movement unit (index feed unit) 200 Workpiece 271 Mirror

Claims

1. A laser processing apparatus comprising: A holding unit for holding the workpiece; a light source that generates a laser beam that is focused and irradiated onto the workpiece held by the holding unit; an index feed unit that moves the holding unit holding the workpiece relative to a focal point of the laser beam in a Y direction; a scanning unit that scans the laser beam generated by the light source in an X direction perpendicular to the Y direction on the workpiece held by the holding unit, The scanning unit includes: a scanner for scanning the laser beam generated by the light source in the X direction; a first lens having a curvature in the X direction that causes the laser beam from the scanner to be incident thereon and perpendicular to the workpiece held by the holding unit; a second lens having a curvature in the Y direction for collecting the laser beam emitted from the first lens in the Y direction; The laser processing apparatus, wherein the length of each of the first lens and the second lens in the X direction is set to be equal to or greater than the length of the workpiece held by the holding unit in the X direction.

2. 2. The laser processing apparatus according to claim 1, wherein the scanner comprises a polygon scanner having a plurality of mirrors for reflecting the laser beam generated by the light source.

3. a liquid supply unit disposed between the second lens and the holding unit and configured to supply liquid to at least an area of ​​the upper surface of the workpiece held by the holding unit that is irradiated with the laser beam; The liquid supply unit includes a transmission window that transmits the laser beam focused by the second lens; 3. The laser processing apparatus according to claim 1, further comprising: a liquid supply section having a liquid jetting port formed adjacent to the transmission window in the Y direction.

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