Method for correcting spot shape of laser beam

Abstract

The present application provides a method for correcting the spot shape of a laser beam, which can suppress the man-hours required for correcting the spot shape of the laser beam, and can reduce the mechanical error between the machining devices for irradiating the laser beam to a workpiece. The method for correcting the spot shape of the laser beam includes the steps of: a laser beam irradiation step of irradiating a laser beam to a concave mirror; a photographing step of photographing the reflected light by a beam analyzer; an image forming step of forming an XZ plane image or a YZ plane image from the XY plane image photographed by the photographing step; and a comparison step of comparing the image formed by the image forming step with the ideal XZ plane image or YZ plane image of the laser beam, wherein the phase pattern displayed on the display portion of the spatial light modulator is changed so that the XZ plane image or YZ plane image formed by the image forming step coincides with the ideal XZ plane image or YZ plane image of the laser beam.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for correcting a spot shape of a laser beam. BACKGROUND

[0002] As a technique for dividing a plate-like object such as a semiconductor wafer into chip size, a technique is known in which a focal point of a laser beam is positioned inside an object to be processed and irradiated along a division predetermined line to form a modified layer as a division starting point (for example, refer to Patent Literature 1).

[0003] However, in an optical system of a laser processing apparatus that performs the above-described laser processing, various optical components are used, and sometimes various optical distortions are generated on an optical path of the optical system. Due to the optical distortions, sometimes the processing results are different between processing apparatuses, and a so-called inter-apparatus mechanical error is generated.

[0004] In order to solve this problem, a technique is proposed in which a concave mirror is held by a chuck table, and light reflected from the concave mirror is photographed to grasp a spot shape at a processing point (for example, refer to Patent Literature 2).

[0005] Patent Literature 1: Japanese Patent No. 3408805

[0006] Patent Literature 2: Japanese Patent Application Laid-Open No. 2016-41437

[0007] However, in the technique shown in Patent Literature 2, even if the spot shape can be grasped, it is not known where the optical distortion is generated in the plurality of optical elements that constitute the optical system, and thus an operation of determining the position of the distortion is required, and there is a problem that the correction of the spot shape takes time. SUMMARY

[0008] Therefore, an object of the present application is to provide a method for correcting a spot shape of a laser beam, which can suppress the working hours required for the correction of the spot shape of the laser beam, and can reduce an inter-apparatus mechanical error of a laser beam irradiated to an object to be processed.

[0009] According to the present application, there is provided a method for correcting a spot shape of a laser beam, which corrects a spot shape of a laser beam condensed by a condensing lens in a laser processing apparatus having: a chuck table which holds a workpiece; a laser beam irradiation unit which irradiates a laser beam to the workpiece held by the chuck table; and a control section, the laser beam irradiation unit including: a laser oscillator; the condensing lens which condenses a laser beam emitted from the laser oscillator; and a spatial light modulator which is disposed between the laser oscillator and the condensing lens, characterized by comprising: a concave mirror arrangement step of positioning a concave mirror having a spherical reflecting surface at a position opposite to the condensing lens of the laser beam irradiation unit; a focal point positioning step of positioning a condensing point of the condensing lens at a focal point position of the concave mirror after the concave mirror arrangement step; a laser beam irradiation step of causing the laser oscillator to operate to irradiate the laser beam condensed by the condensing lens to the concave mirror; a photographing step of photographing reflected light reflected by the reflecting surface of the concave mirror by a photographing unit; an image formation step of forming an XZ plane image or a YZ plane image from an XY plane image representing a shape and an intensity distribution of the laser beam photographed by the photographing step; and a comparison step of comparing the image formed by the image formation step with an XZ plane image or a YZ plane image of a laser beam having an ideal shape and an intensity distribution, and changing a phase pattern displayed on a display section of the spatial light modulator so that the XZ plane image or the YZ plane image formed by the image formation step coincides with the XZ plane image or the YZ plane image of the laser beam having the ideal shape and the intensity distribution.

[0010] Preferably, the method for correcting a spot shape of a laser beam further includes a judgment step of judging what aberration component is included in the image of the laser beam photographed by the photographing step, and a display step of displaying a phase pattern in which the aberration component judged by the judgment step is eliminated on the display section of the spatial light modulator.

[0011] Preferably, the method for correcting a spot shape of a laser beam further includes a judgment step of judging what aberration component is included in the image of the laser beam photographed by the photographing step, and a storage step of storing what aberration component is included in the laser beam having the ideal shape and the intensity distribution, and changing the phase pattern displayed on the display section of the spatial light modulator so that the aberration component of the laser beam photographed by the photographing step coincides with the aberration component of the ideal laser beam.

[0012] Preferably, in the comparison step, if a difference of the compared images is equal to or less than a prescribed ratio, it is acceptable, and if the difference of the compared images is greater than the prescribed ratio, the correction of the spot shape is performed again.

[0013] The present application has the effects of being able to suppress the man-hours required for correction of the spot shape of the laser beam and being able to reduce mechanical errors among processing devices that irradiate the laser beam to the workpiece. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a perspective view showing a structure example of a laser processing device that implements the correction method of the spot shape of the laser beam of the first embodiment.

[0015] Figure 2 is a perspective view showing a structure example of a laser processing device that implements the correction method of the spot shape of the laser beam of the first embodiment. Figure 1 is a schematic view showing a structure of a laser beam irradiation unit of the laser processing device shown in

[0016] Figure 3 is a schematic view showing a structure of a laser beam irradiation unit of the laser processing device shown in Figure 1 is a schematic view showing an XY plane image of the shape and intensity distribution of the reflected light of the laser beam that is obtained by the beam analyzer of the laser processing device shown in

[0017] Figure 4 is a view showing an XZ plane image along the line A-A' in Figure 3

[0018] Figure 5 is a view showing an XZ plane image along the line B-B' in Figure 3

[0019] Figure 6 is a view showing an XZ plane image along the line C-C' in Figure 3

[0020] Figure 7 is a view showing a YZ plane image along the line A1-A1' in Figure 3

[0021] Figure 8 is a view showing a YZ plane image along the line B1-B1' in Figure 3

[0022] Figure 9 is a view showing a YZ plane image along the line C1-C1' in Figure 3

[0023] Figure 10 is a view showing an ideal XY plane image of the laser beam having an ideal shape and intensity distribution of the correction method of the spot shape of the laser beam of the first embodiment.

[0024] Figure 11 is a flowchart that explains the correction method of the spot shape of the laser beam of the first embodiment.

[0025] Figure 12 is a view showing a laser processing device that implements the correction method of the spot shape of the laser beam of the first embodiment.​​​​​​Figure 11 FIG. 1 is a diagram showing an example of an XY plane image of reflected light taken in the photographing step of the correction method of the spot shape of the laser beam.

[0026] Figure 13 is a diagram showing an example of an XZ plane image displayed on the display unit in the comparison step of the correction method of the spot shape of the laser beam. Figure 11 FIG. 1 is a diagram showing an example of an XY plane image of reflected light taken in the photographing step of the correction method of the spot shape of the laser beam.

[0027] Figure 14 is a diagram showing an example of an XZ plane image displayed on the display unit in the comparison step of the correction method of the spot shape of the laser beam. Figure 11 FIG. 1 is a diagram showing an example of an XY plane image of reflected light taken in the photographing step of the correction method of the spot shape of the laser beam.

[0028] Figure 15 is a diagram showing an example of an XZ plane image displayed on the display unit in the comparison step of the correction method of the spot shape of the laser beam.

[0029] Figure 16 is a diagram showing an example of an XZ plane image displayed on the display unit in the comparison step of the correction method of the spot shape of the laser beam. Figure 15 FIG. 1 is a diagram showing an example of an XY plane image of reflected light taken in the photographing step of the correction method of the spot shape of the laser beam.

[0030] Figure 17 is a diagram showing an example of an XY plane image of reflected light in which the Zernike coefficient corresponding to the astigmatism aberration 0° is a value or more than a prescribed value.

[0031] Figure 18 is a diagram showing an example of an XY plane image of reflected light in which the Zernike coefficient corresponding to the astigmatism aberration 90° is a value or more than a prescribed value.

[0032] Figure 19 is a diagram showing an example of an XY plane image of reflected light in which the Zernike coefficient corresponding to the astigmatism aberration +45° is a value or more than a prescribed value.

[0033] Figure 20 is a diagram showing an example of an XY plane image of reflected light in which the Zernike coefficient corresponding to the astigmatism aberration -45° is a value or more than a prescribed value.

[0034] Figure 21 is a diagram showing an example of an XY plane image of reflected light in which the Zernike coefficient corresponding to the coma aberration +X is a value or more than a prescribed value.

[0035] Figure 22 is a diagram showing an example of an XY plane image of reflected light in which the Zernike coefficient corresponding to the coma aberration -X is a value or more than a prescribed value.

[0036] Figure 23 is a diagram showing an example of an XY plane image of reflected light in which the Zernike coefficient corresponding to the coma aberration +Y is a value or more than a prescribed value.

[0037] Figure 24is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to the coma -Y is a value or more.

[0038] Figure 25 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to the spherical aberration + is a value or more.

[0039] Figure 26 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to the spherical aberration - is a value or more.

[0040] Figure 27 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to the trefoil aberration +X is a value or more.

[0041] Figure 28 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to the trefoil aberration -X is a value or more.

[0042] Figure 29 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to the trefoil aberration +Y is a value or more.

[0043] Figure 30 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to the trefoil aberration -Y is a value or more.

[0044] Figure 31 is a perspective view showing a structure example of a laser processing apparatus of a correction method of a laser beam spot shape which implements a modification example of the first embodiment and the second embodiment.

[0045] Explanation of reference numerals

[0046] 1, 1-1, 1-2: laser processing apparatus; 10: chuck table (chuck table); 20: laser beam irradiation unit; 21: laser beam; 22: laser oscillator; 23: condenser lens; 24: spatial light modulator; 25: concave mirror; 28: beam analyzer (shooting unit); 100: control section; 200: workpiece; 211: condensing point; 212: reflected light; 241: display section; 251: focal point; 252: reflecting surface; 400: XY plane image; 500: XZ plane image; 501: XZ plane image (XZ plane image of a laser beam having an ideal shape and intensity distribution); 600: YZ plane image; 601: YZ plane image (YZ plane image of a laser beam having an ideal shape and intensity distribution); ST1: storage step; ST2: concave mirror arrangement step; ST3: focal point positioning step; ST4: laser beam irradiation step; ST5: shooting step; ST6: image formation step; ST7: comparison step; ST9: determination step. DETAILED DESCRIPTION

[0047] Embodiments of the present application will be described below in detail with reference to the accompanying drawings. The present application is not limited to the contents described in the following embodiments. In addition, among the structural elements described below, there are structural elements that are substantially the same as those that can be easily conceived by those skilled in the art. Furthermore, the structures described below can be appropriately combined. In addition, various omissions, substitutions, or alterations of the structures can be made within the scope of the gist of the present application.

[0048] [1st Embodiment]

[0049] A method of correcting a spot shape of a laser beam according to the 1st embodiment of the present application will be described with reference to the drawings. First, the structure of a laser processing apparatus 1 that implements the method of correcting a spot shape of a laser beam according to the 1st embodiment will be described. Figure 1 is a perspective view showing an example of the structure of a laser processing apparatus that implements the method of correcting a spot shape of a laser beam according to the 1st embodiment. The laser processing apparatus 1 according to the 1st embodiment Figure 1 The laser processing apparatus 1 shown in FIG. 1 is an apparatus that performs laser processing on a workpiece 200 by irradiating the workpiece 200 with a pulsed laser beam 21.

[0050] As the laser processing apparatus 1 shown in FIG. 1, a laser processing apparatus that performs laser processing on a workpiece 200 by irradiating the workpiece 200 with a pulsed laser beam 21 is used. Figure 1 The workpiece 200 that is the processing target of the laser processing apparatus 1 shown in FIG. 1 is a wafer such as a semiconductor wafer or an optical device wafer that has a circular plate-shaped substrate 201 made of silicon, sapphire, gallium arsenide, or the like. As shown in Figure 1 As shown in FIG. 2, the workpiece 200 has division predetermined lines 203 that are set in a lattice shape on a front surface 202 of the substrate 201, and devices 204 that are formed in regions divided by the division predetermined lines 203. The devices 204 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integrations), image sensors such as CCDs (Charge Coupled Devices) or CMOSs (Complementary Metal Oxide Semiconductors).

[0051] In the 1st embodiment, the workpiece 200 is supported in the opening of the annular frame 206 with an adhesive tape 207 that is a circular plate-shaped member having a larger diameter than the outer diameter of the workpiece 200 and that is adhered to the outer edge portion of the annular frame 206 adhered to the back surface 205 of the front surface 202. In the 1st embodiment, the workpiece 200 is divided into the individual devices 204 along the division predetermined lines 203.

[0052] (Laser Processing Apparatus)

[0053] like Figure 1 As shown, the laser processing apparatus 1 includes a chuck table 10, which serves as a chuck table for holding a workpiece 200 using a holding surface 11; a laser beam irradiation unit 20, which serves as a laser beam irradiation unit; a moving unit 30; an imaging unit 40; and a control unit 100.

[0054] The chuck stage 10 holds the workpiece 200 using a holding surface 11. The chuck stage 10 is disc-shaped and includes: a disc-shaped suction part 12 made of porous ceramic or the like with multiple holes, having a flat holding surface 11 on its upper surface for holding the workpiece 200; and a frame 13 that embeds and fixes the suction part 12 into a central recess on the upper surface. The upper surface of the frame 13 is on the same plane as the holding surface 11. In the first embodiment, the upper surface of the frame 13 is the periphery of the chuck stage 10. The suction part 12 of the chuck stage 10 is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). The chuck stage 10 attracts and holds the workpiece 200 placed on the holding surface 11. In the first embodiment, the holding surface 11 is a plane parallel to the horizontal direction. A plurality of clamping parts 14 are arranged around the chuck table 10, which clamp the workpiece 200 supported in the opening by the annular frame 206.

[0055] Furthermore, the chuck table 10 rotates about an axis parallel to the Z-axis direction via the rotary moving unit 34 of the moving unit 30. The Z-axis direction is perpendicular to the holding surface 11 and parallel to the vertical direction. The chuck table 10, together with the rotary moving unit 34, moves along the X-axis direction (parallel to the horizontal direction) via the X-axis moving unit 31 of the moving unit 30, and moves along the Y-axis direction (parallel to the horizontal direction and perpendicular to the X-axis direction) via the Y-axis moving unit 32.

[0056] The laser beam irradiation unit 20 is a laser beam irradiation unit that irradiates the workpiece 200 held by the chuck stage 10 with a pulsed laser beam 21 of a wavelength that is transparent to the workpiece 200, forming a modified layer inside the workpiece 200 as a fracture initiation point. The modified layer refers to a region whose density, refractive index, mechanical strength, and other physical properties differ from those of its surroundings. Examples of modified layers include melt-processed regions, cracked regions, insulation failure regions, refractive index change regions, and regions where these regions are mixed. In this embodiment, the mechanical strength of the modified layer is lower than that of other parts of the substrate 201.

[0057] Further, in the first embodiment, the laser beam irradiation unit 20 irradiates the workpiece 200 with a laser beam 21 having a wavelength that is transmissive to the workpiece 200, but in the present application, a laser beam 21 having a wavelength that is absorptive to the workpiece 200 can be irradiated to perform ablation processing on the workpiece 200. In the first embodiment, as shown in FIG. 1, a part of the laser beam irradiation unit 20 is supported by a lifting member 4 that moves along the Z-axis direction by a Z-axis moving unit 33 of a moving unit 30 provided on a standing wall 3 that is vertically provided from a device main body 2. Further, the structure of the laser beam irradiation unit 20 and the like will be described later. Figure 1

[0058] The moving unit 30 relatively moves the chuck table 10 and the laser beam irradiation unit 20 in the X-axis direction, the Y-axis direction, and the Z-axis direction. Further, the X-axis direction and the Y-axis direction are directions parallel to the holding surface 11. The moving unit 30 has an X-axis moving unit 31 that moves the chuck table 10 in the X-axis direction as a processing feed unit, a Y-axis moving unit 32 that moves the chuck table 10 in the Y-axis direction as an indexing feed unit, a Z-axis moving unit 33 that moves the condenser lens 23 included in the laser beam irradiation unit 20 in the Z-axis direction, and a rotational moving unit 34 that rotates the chuck table 10 around an axis parallel to the Z-axis direction.

[0059] In the first embodiment, the Y-axis moving unit 32 is provided on the device main body 2 of the laser processing device 1. The Y-axis moving unit 32 supports a moving plate 15 that supports the X-axis moving unit 31 so as to be movable in the Y-axis direction. The X-axis moving unit 31 is provided on the moving plate 15. The X-axis moving unit 31 supports a second moving plate 16 that supports the rotational moving unit 34 that rotates the chuck table 10 around an axis parallel to the Z-axis direction so as to be movable in the X-axis direction. The Z-axis moving unit 33 is provided on the standing wall 3 and supports the lifting member 4 so as to be movable in the Z-axis direction.

[0060] The X-axis moving unit 31, the Y-axis moving unit 32, and the Z-axis moving unit 33 have a publicly known ball screw that is rotatably provided around an axis, a publicly known pulse motor that rotates the ball screw around the axis, and a publicly known guide rail that supports the moving plates 15 and 16 so as to be movable in the X-axis direction or the Y-axis direction and supports the lifting member 4 so as to be movable in the Z-axis direction.

[0061] ​Further, the laser processing apparatus 1 has an X-axis direction position detection unit (not shown) for detecting the position of the chuck table 10 in the X-axis direction, a Y-axis direction position detection unit (not shown) for detecting the position of the chuck table 10 in the Y-axis direction, and a Z-axis direction position detection unit for detecting the position of the condenser lens 23 included in the laser beam irradiation unit 20 in the Z-axis direction. Each of the position detection units outputs the detection result to the control section 100.

[0062] The photographing unit 40 photographs the workpiece 200 held by the chuck table 10. The photographing unit 40 has a photographing element such as a CCD (Charge Coupled Device) photographing element or a CMOS (Complementary MOS) photographing element that photographs the workpiece 200 held by the chuck table 10. In the first embodiment, the photographing unit 40 is attached to the front end of the housing of the laser beam irradiation unit 20 and is disposed at a position in the X-axis direction in which the photographing unit 40 is aligned with the condenser lens 23 of the laser beam irradiation unit 20. Figure 2 The photographing unit 40 photographs the workpiece 200 held by the chuck table 10. The photographing unit 40 has a photographing element such as a CCD (Charge Coupled Device) photographing element or a CMOS (Complementary MOS) photographing element that photographs the workpiece 200 held by the chuck table 10. In the first embodiment, the photographing unit 40 is attached to the front end of the housing of the laser beam irradiation unit 20 and is disposed at a position in the X-axis direction in which the photographing unit 40 is aligned with the condenser lens 23 of the laser beam irradiation unit 20.

[0063] The control section 100 controls each of the above-described structural elements of the laser processing apparatus 1 to cause the laser processing apparatus 1 to perform a processing operation on the workpiece 200. Further, the control section 100 is a computer that has 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 section 100 performs an arithmetic process in accordance with a computer program stored in the storage device and outputs a control signal for controlling the laser processing apparatus 1 to each of the above-described structural elements of the laser processing apparatus 1 via the input / output interface device, thereby realizing the functions of the control section 100.

[0064] Further, the laser processing apparatus 1 has a display unit 110 constituted by a liquid crystal display device or the like that displays the state or an image of the processing operation and the like, and an input unit 111 used when an operator registers processing content information or the like. The display unit 110 and the input unit 111 are connected to the control section 100. The input unit 111 is constituted by at least one of an external input device such as a touch panel and a keyboard provided to the display unit 110.

[0065] Next, the laser beam irradiation unit 20 will be described. Figure 2 is a view illustrating Figure 1 is a view illustrating the structure of the laser beam irradiation unit of the laser processing apparatus. Figure 3 is a view illustrating Figure 1 is a view illustrating the XY plane image of the shape and intensity distribution of the reflected light of the laser beam, which is obtained by the beam profiler of the laser processing apparatus shown in FIG. 1A, by photographing the reflected light. As shown in FIG. 1B, the XY plane image of the reflected light of the laser beam is obtained by photographing the reflected light of the laser beam, which is reflected by the processed object 200, with the beam profiler 28. Figure 2 As shown in FIG. 1A, the laser beam irradiation unit 20 has a laser oscillator 22 that oscillates a pulsed laser for processing the processed object 200, a condenser lens 23 that condenses the laser beam 21 emitted from the laser oscillator 22 at the processed object 200 held by the holding surface 11 of the chuck table 10, a spatial light modulator 24, a concave mirror 25, a beam splitter 26 as a branching unit, an attenuating unit 27, a beam profiler 28 as a photographing unit, and a plurality of optical members 29.

[0066] The condenser lens 23 is disposed at a position opposed to the holding surface 11 of the chuck table 10 in the Z-axis direction, transmits the laser beam 21 emitted from the laser oscillator 22, and thereby condenses the laser beam 21 at a condensing point 211.

[0067] The spatial light modulator 24 is disposed on the optical path of the laser beam 21 between the laser oscillator 22 and the condenser lens 23, is a so-called LCOS-SLM (Liquid Crystal on Silicon-Spatial Light Modulator) that adjusts the optical characteristics of the laser beam 21 emitted from the laser oscillator 22 and emits the laser beam 21 whose optical characteristics are adjusted. In the first embodiment, the spatial light modulator 24 is a modulator that reflects the laser beam 21 emitted from the laser oscillator 22. In the first embodiment, the optical characteristics of the laser beam 21 adjusted by the spatial light modulator 24 are at least one of the phase, the polarization plane, the amplitude, the intensity, and the propagation direction of the laser beam 21, for example.

[0068] In the first embodiment, the spatial light modulator 24 has a display portion 241 to which the laser beam 21 emitted from the laser oscillator 22 is irradiated, adjusts the optical characteristics when reflecting the laser beam 21, and emits the laser beam 21 whose optical characteristics are adjusted by the display portion 241 toward the condenser lens 23 via the beam splitter 26 or the like. In the first embodiment, the display portion 241 of the spatial light modulator 24 displays a phase pattern for adjusting the optical characteristics of the laser beam 21, and adjusts the optical characteristics of the laser beam 21 by reflecting the laser beam 21. The phase pattern is controlled by the control portion 100. The spatial light modulator 24 adjusts the optical characteristics of the emitted laser beam 21 by controlling the phase pattern displayed on the display portion 241 by the control portion 100.

[0069] The concave mirror 25 is disposed at a position capable of being opposed to the condenser lens 23 in the Z-axis direction, has a reflecting surface 252 capable of being positioned to have a focal point 251 at the condensing point 211 of the condenser lens 23 when being opposed to the condenser lens 23 in the Z-axis direction. The reflecting surface 252 is a spherical surface, and reflects the laser beam 21 emitted from the condenser lens 23 opposed in the Z-axis direction toward the condenser lens 23. In the first embodiment, the concave mirror 25 is disposed inside the frame 13 of the chuck table 10, and the reflecting surface 252 is disposed at a position capable of being opposed to the condenser lens 23 in the Z-axis direction. In the first embodiment, the position of the condenser lens 23 in the Z-axis direction is adjusted by the Z-axis moving unit 33 so that the condensing point 211 of the condenser lens 23 is positioned at the focal point 251, thereby positioning the focal point 251 of the reflecting surface 252 at the condensing point 211 of the condenser lens 23.

[0070] The beam splitter 26 passes the laser beam 21 emitted from the laser oscillator 22 and whose optical characteristics are adjusted by the spatial light modulator 24 toward the condenser lens 23. The beam splitter 26 reflects the reflected light 212 of the laser beam 21 that is condensed by the condenser lens 23 and is reflected by the reflecting surface 252 of the concave mirror 25 so as to pass through the condenser lens 23, toward the attenuation unit 27, and branches the reflected light 212 from the laser beam 21.

[0071] The attenuation unit 27 is used to attenuate the intensity of the reflected light 212 reflected by the beam splitter 26. In the first embodiment, the attenuation unit 27 attenuates the intensity of the reflected light 212 and reflects it toward the beam analyzer 28. The attenuation unit 27 is constituted by a wedge-shaped substrate, for example.

[0072] The beam analyzer 28 photographs the reflected light 212 reflected by the reflecting surface 252 of the concave mirror 25, branched from the laser beam 21 by the beam splitter 26, and whose intensity is attenuated by the attenuation unit 27, and acquires an XY plane image 400 of the laser beam 21. Figure 3The XY plane image 400 has (indicates) the shape and spatial intensity distribution of the reflected light 212 of the laser beam 21. The light beam analyzer 28 outputs the acquired XY plane image 400 to the control section 100. In addition, the XY plane image 400 acquired by the light beam analyzer 28 indicates the intensity of each position in the X-axis direction and the Y-axis direction of the reflected light 212.

[0073] The optical member 29 propagates the laser beam 21 emitted from the laser oscillator 22 toward the machining point or the concave mirror 25 that machines the work 200, and propagates the reflected light 212 of the laser beam 21 reflected by the reflecting surface 252 of the concave mirror 25 toward the light beam analyzer 28. In the first embodiment, the optical member 29 has a beam expander 29-1, a mirror 29-2, and a wavelength plate 29-3 provided on the optical path of the laser beam 21 between the laser oscillator 22 and the spatial light modulator 24. In the first embodiment, the beam expander 29-1, the mirror 29-2, and the wavelength plate 29-3 are sequentially arranged from the laser oscillator 22 toward the spatial light modulator 24. In addition, the optical member 29 has a relay optical system 29-4 provided on the optical path of the laser beam 21 between the spatial light modulator 24 and the beam splitter 26, and a mirror 29-5 provided on the optical path of the laser beam 21 between the beam splitter 26 and the condenser lens 23.

[0074] In addition, as Figure 1 indicated, the control section 100 of the laser machining device 1 of the first embodiment has an image forming section 101, a phase pattern generating section 102, and a storage section 103. Next, each structural element of the control section 100 will be described. Figure 4 is a graph showing an XZ plane image along the A-A' line in Figure 3 . Figure 5 is a graph showing an XZ plane image along the B-B' line in Figure 3 . Figure 6 is a graph showing an XZ plane image along the C-C' line in Figure 3 . Figure 7 is a graph showing a YZ plane image along the A1-A1' line in Figure 3 . Figure 8 is a graph showing a YZ plane image along the B1-B1' line in Figure 3 . Figure 9 is a graph showing a YZ plane image along the C1-C1' line in Figure 3 .

[0075] In the image forming section 101, the light beam analyzer 28 photographs the reflected light 212, and outputs the acquired XY plane image 400 of the laser beam 21 having the shape and spatial intensity distribution of the reflected light 212 of the laser beam 21 to the display unit 110 and displays it on the display unit 110.

[0076] In addition, the image forming section 101 forms an XZ plane image 500 exemplified in Figure 4 , Figure 5 and Figure 6 from the XY plane image 400 of the reflected light 212, and outputs the formed XZ plane image 500 to the display unit 110 and displays it on the display unit 110. In addition, the XZ plane image 500 is an image on a cross section parallel to both the X-axis direction and the Z-axis direction of the reflected light 212 of the laser beam 21. The image forming section 101 forms a YZ plane image 600 exemplified in Figure 7 , Figure 8 and Figure 9 from the XY plane image 400 of the reflected light 212, and outputs the formed XZ plane image 500 to the display unit 110 and displays it on the display unit 110. The YZ plane image 600 is an image on a cross section parallel to both the Y-axis direction and the Z-axis direction of the reflected light 212 of the laser beam 21. In addition, in the present application, the X-axis direction and the Y-axis direction are not limited to the directions of X and Y in Figure 3 .

[0077] Figure 4 , Figure 5 , Figure 6 and Figure 7 , Figure 8 and Figure 9 The XZ plane image 500 exemplified in Figure 4 , Figure 5 and Figure 6 indicates the position of the X-axis direction, Figure 7 , Figure 8 and Figure 9 indicates the position of the Y-axis direction, Figure 4 to Figure 9 and the vertical axis of indicates the intensity of the reflected light 212 of the laser beam 21.

[0078] The phase pattern generation unit 102 generates a phase pattern having multiple Zernike coefficients of predetermined values ​​input from the input unit 111, and displays the generated phase pattern on the display unit 241 of the spatial light modulator 24. Furthermore, each Zernike coefficient corresponds to a different aberration generated at the beam point by the optical system of the laser beam irradiation unit 20. Examples of aberrations in the optical system of the laser beam irradiation unit 20 include: "astigmatism 0°", "astigmatism 90°", "astigmatism +45°", "astigmatism -45°", "coma +X", "coma -X", "coma +Y", "coma -Y", "spherical aberration +", "spherical aberration -", "cloverleaf aberration +X", "cloverleaf aberration -X", "cloverleaf aberration +Y", and "cloverleaf aberration -Y".

[0079] The phase pattern generation unit 102 receives predetermined values ​​for each Zernike coefficient input from the input unit 111. When all Zernike coefficient values ​​are received, it generates a phase pattern with the received Zernike coefficient values. The phase pattern generation unit 102 displays the generated phase pattern on the display unit 241. Furthermore, when the operator manipulates the input unit 111 to change the value of any Zernike coefficient and receives the changed Zernike coefficient value, the phase pattern generation unit 102 generates a phase pattern with the changed Zernike coefficient value and displays it on the display unit 241.

[0080] Storage unit 103 stores the ideal XY plane image 401 ( Figure 10 As shown), the ideal XY plane image 401 has the shape and spatial intensity distribution of the reflected light 212 of the laser beam 21 that obtains the ideal processing result at the processing point in the processing action input from the input unit 111, etc. Figure 10 This is a diagram showing an ideal XY plane image of a laser beam with an ideal shape and intensity distribution, illustrating the laser beam spot shape correction method of the first embodiment.

[0081] Furthermore, the ideal XY plane image 401 is an XY plane image obtained by the beam analyzer 28 by capturing the reflected light 212 of the laser beam 21, which achieves the desired processing result at the processing point during the processing operation. Additionally, the Zernike coefficients of the reflected light 212 of the laser beam 21 that generates the ideal XY plane image 401 are ideal values ​​for each Zernike coefficient. Furthermore, in this invention, all Zernike coefficients of the ideal XY plane image 401 are below a predetermined value.

[0082] Furthermore, the functions of the image forming unit 101 and the phase pattern generating unit 102 are implemented by an arithmetic processing device performing arithmetic processing according to a computer program stored in a storage device. The functions of the storage unit 103 are implemented by a storage device.

[0083] When the operator registers the processing content information in the control section 100 and places the work 200 with the adhesive tape 207 interposed therebetween on the holding surface 11 of the chuck table 10 and the control section 100 accepts the operator's processing operation start instruction from the input unit 111, the laser processing apparatus 1 starts the processing operation in accordance with the registered processing content information.

[0084] In the processing operation, the laser processing apparatus 1 holds the work 200 with the adhesive tape 207 interposed therebetween to the holding surface 11 of the chuck table 10 and clamps the annular frame 206 with the clamping section 14. Next, the moving unit 30 moves the chuck table 10 toward the lower side of the photographing unit 40, and the photographing unit 40 photographs the work 200. The laser processing apparatus 1 performs alignment based on the image photographed by the photographing unit 40.

[0085] The laser processing apparatus 1 relatively moves the laser beam irradiation unit 20 and the work 200 along the division predetermined line 203 by the moving unit 30 in accordance with the processing content information, and irradiates the pulse-shaped laser beam 21 from the laser beam irradiation unit 20 toward the division predetermined line 203. In the first embodiment, the laser processing apparatus 1 irradiates the laser beam 21, and forms a modified layer inside the substrate 201 along the division predetermined line 203. When the modified layer is formed inside the substrate 201 along all the division predetermined lines 203, the laser processing apparatus 1 stops the irradiation of the laser beam 21, and ends the processing operation.

[0086] The laser processing apparatus 1 performs the following correction method of the spot shape of the laser beam before the processing operation is started. Next, the correction method of the spot shape of the laser beam will be described. Figure 11 is a flowchart illustrating the correction method of the spot shape of the laser beam of the first embodiment. Figure 12 is a diagram illustrating an example of the XY plane image acquired by photographing the reflected light in the photographing step of the correction method of the spot shape of the laser beam illustrated in Figure 11 Figure 13 is a diagram illustrating an example of the XZ plane image displayed on the display unit in the comparison step of the correction method of the spot shape of the laser beam illustrated in Figure 11 Figure 14 is a diagram illustrating an example of the YZ plane image displayed on the display unit in the comparison step of the correction method of the spot shape of the laser beam illustrated in Figure 11

[0087] The correction method of the spot shape of the laser beam of the first embodiment (hereinafter referred to as the correction method) is a method of making the XY plane image 400 (illustrated in Figure 12 illustrated) representing the shape and intensity distribution of the reflected light of the laser beam close to an ideal XY plane image 401 (​​​Figure 10 The correction method of the first embodiment is a method of adjusting the phase pattern displayed on the display portion 241 of the spatial light modulator 24 to be able to irradiate the laser beam 21 that obtains the ideal processing result at the processing point in the processing operation, in order to make the XY plane image 400 of the reflected light 212 of the laser beam 21 taken by the beam analyzer 28 approach the ideal XY plane image 401.

[0088] As shown in Fig. 1, the correction method has a storage step ST1, a concave mirror arrangement step ST2, a focal point positioning step ST3, a laser beam irradiation step ST4, a photographing step ST5, an image formation step ST6, a comparison step ST7, and a determination step ST9. Figure 11 As shown in Fig. 1, the correction method has a storage step ST1, a concave mirror arrangement step ST2, a focal point positioning step ST3, a laser beam irradiation step ST4, a photographing step ST5, an image formation step ST6, a comparison step ST7, and a determination step ST9.

[0089] The storage step ST1 is a step of storing the ideal XY plane image 401 having the shape and the spatial intensity distribution of the reflected light 212 of the laser beam 21 that obtains the ideal processing result at the processing point in the processing operation in the storage portion 103. In the first embodiment, in the storage step ST1, the control portion 100 stores the ideal XY plane image 401 in the storage portion 103, accepting the operation of the input unit 111 by the operator.

[0090] The concave mirror arrangement step ST2 is a step of positioning the concave mirror 25 having the spherical reflecting surface 252 at a position opposite to the condenser lens 23 of the laser beam irradiation unit 20 in the Z-axis direction. In the first embodiment, in the concave mirror arrangement step ST2, the control portion 100 controls the X-axis moving unit 31 and the Y-axis moving unit 32 so that the condenser lens 23 of the laser beam irradiation unit 20 and the reflecting surface 252 of the concave mirror 25 are opposite in the Z-axis direction.

[0091] The focal point positioning step ST3 is a step of positioning the condensing point 211 of the condenser lens 23 at the position of the focal point 251 of the concave mirror 25 after the concave mirror arrangement step ST2. In the first embodiment, in the focal point positioning step ST3, the control portion 100 controls the Z-axis moving unit 33 so that the condensing point 211 of the condenser lens 23 is positioned at the focal point 251 of the reflecting surface 252.

[0092] The laser beam irradiation step ST4 is a step of causing the laser oscillator 22 to operate, emitting the laser beam 21 from the laser oscillator 22, and irradiating the laser beam 21 condensed by the condenser lens 23 to the reflecting surface 252 of the concave mirror 25. In the laser beam irradiation step ST4, the control section 100 receives the operation of the input section 111 by the operator, and stores each Zernike coefficient of a prescribed value. Note that, in the first embodiment, the prescribed value is an arbitrary value. In the laser beam irradiation step ST4, when the phase pattern generation section 102 receives the values of all the Zernike coefficients, the phase pattern having the Zernike coefficients of the received values is generated. In the laser beam irradiation step ST4, the phase pattern generation section 102 displays the generated phase pattern on the display section 241.

[0093] In the first embodiment, in the laser beam irradiation step ST4, after the phase pattern generated by the phase pattern generation section 102 is displayed on the display section 241, the control section 100 causes the laser oscillator 22 to operate to oscillate the laser. In the laser beam irradiation step ST4, the laser beam 21 emitted from the laser oscillator 22 is irradiated to the reflecting surface 252 of the concave mirror 25 via the spatial light modulator 24, the beam splitter 26, the condenser lens 23, and the like. The optical characteristics of the laser beam 21 irradiated to the reflecting surface 252 are characteristics corresponding to the phase pattern generated by the phase pattern generation section 102 and displayed on the display section 241.

[0094] The photographing step ST5 is a step of photographing the reflected light 212 of the laser beam 21 reflected by the reflecting surface 252 of the concave mirror 25 by the beam profiler 28. In the first embodiment, in the photographing step ST5, the reflected light 212 of the laser beam 21 reflected by the reflecting surface 252 is reflected toward the attenuating section 27 by the beam splitter 26, and is photographed by the beam profiler 28. In the first embodiment, in the photographing step ST5, the beam profiler 28 photographs the reflected light 212 of the laser beam 21, acquires the XY plane image 400 (shown in FIG. 4) of the reflected light 212 of the laser beam 21 having the shape and the spatial intensity distribution of the reflected light 212 of the laser beam 21, and outputs the acquired XY plane image 400 to the control section 100. Figure 12

[0095] The image formation step ST6 is a step of forming an XZ plane image 500 (shown in FIG. 5) or a YZ plane image 600 (shown in FIG. 6) from the XY plane image 400 of the reflected light 212 of the laser beam 21 representing the shape and the spatial intensity distribution of the reflected light 212 of the laser beam 21 acquired in the photographing step ST5. Figure 13 Figure 14

[0096] ​​​In the first embodiment, during the image forming step ST6, the image forming unit 101 of the control unit 100 outputs an XY plane image 400 of the reflected light 212 of the laser beam 21, which has the shape and spatial intensity distribution of the reflected light 212 of the laser beam 21 and was captured in the shooting step ST5, to the display unit 110, and displays the XY plane image 400 on the display unit 110. In the first embodiment, during the image forming step ST6, while the XY plane image 400 is displayed on the display unit 110, the image forming unit 101 receives an operation from the input unit 111, and forms an XZ plane image 500 and a YZ plane image 600 of the XY plane image 400, which are cross-sections of the XY plane image 400 corresponding to the operator's operation.

[0097] Comparison step ST7 is to compare the XZ plane image 500 (in the image formation step ST6) of the image formed in step ST6. Figure 13 An example is shown in solid lines in the image) or YZ plane image 600 (in Figure 14 An example is shown in solid lines in the image) and the XZ plane image 501 of the ideal XY plane image 401 (in the image). Figure 13 An example is shown in the image (using a single-dot dashed line) or YZ plane image 601 (in Figure 14 The steps for comparison are shown in the example (using a single-dotted line). Additionally, Figure 13 The horizontal axis represents the position in the X-axis direction. Figure 14 The horizontal axis represents the position in the Y-axis direction. Figure 13 and Figure 14 The vertical axis represents the intensity of the reflected light 212 of the laser beam 21. In addition, the XZ plane image 501 is an XZ plane image of the reflected light 212 of the laser beam 21 with an ideal shape and intensity distribution, and the YZ plane image 601 is a YZ plane image of the reflected light 212 of the laser beam 21 with an ideal shape and intensity distribution.

[0098] In the first embodiment, in the comparison step ST7, the image forming unit 101 forms an XZ plane image 501 and a YZ plane image 601 with cross-sections corresponding to the operator's operation based on the ideal XY plane image 401. For example... Figure 13 As shown, the control unit 100 displays the XZ plane image 500 formed in the image forming step ST6 and the XZ plane image 501 formed according to the ideal XY plane image 401 overlapping on the display unit 110. Additionally, as... Figure 14 As shown, the YZ plane image 600 formed in the image forming step ST6 is superimposed on the YZ plane image 601 formed according to the ideal XY plane image 401 and displayed on the display unit 110.

[0099] Further, although the XZ plane images 500, 501 are displayed superimposed on the display unit 110 and the YZ plane images 600, 601 are displayed superimposed on the display unit 110, in the present application, it is sufficient to implement at least one of the action of displaying the XZ plane images 500, 501 superimposed on the display unit 110 and the action of displaying the YZ plane images 600, 601 superimposed on the display unit 110.

[0100] Then, the operator determines whether or not the difference of at least one of the XZ plane images 500, 501 and the YZ plane images 600, 601 which are the images displayed superimposed on the display unit 110 and compared in the comparison step ST7 is below the prescribed ratio (step ST8). When the operator determines that the difference of at least one of the XZ plane images 500, 501 and the YZ plane images 600, 601 is larger than the prescribed ratio (step ST8: No), the determination step ST9 is entered.

[0101] The determination step ST9 is a step of determining what kind of aberration component the XY plane image 400 having the shape and the spatial intensity distribution of the reflected light 212 of the laser beam 21 taken in the taking step ST5 contains. In the first embodiment, in the determination step ST9, the control section 100 displays at least the XY plane image 400 on the display unit 110 in response to the operation of the input unit 111 by the operator. Further, in addition to the XY plane image 400, the ideal XY plane image 401 can be displayed on the display unit 110, and further, the XZ plane images 500, 501 and the YZ plane images 600, 601 can be displayed.

[0102] In the determination step ST9, the operator determines the largest aberration of the XY plane image 400 from the ideal XY plane image 401 from at least one of the difference points between the XY plane images 400, 401, the difference points between the XZ plane images 500, 501, and the difference points between the YZ plane images 600, 601. Thus, in the determination step ST9, by determining the largest aberration of the XY plane image 400 from the ideal XY plane image 401, it is determined what kind of aberration component the XY plane image 400 contains.

[0103] Then, the operator operates the input unit 111 to change the value of the Zernike coefficient corresponding to the aberration determined in the determination step ST9 to a prescribed value to approach an ideal value. When the phase pattern generation unit 102 of the control unit 100 receives the changed value of the Zernike coefficient, a phase pattern having the changed value of the Zernike coefficient is generated and displayed on the display unit 241 (step ST10), and then returns to the laser beam irradiation step ST4. In this way, by displaying a phase pattern in which the aberration determined in the determination step ST9 is eliminated on the display unit 241 of the spatial light modulator 24, the aberration component of the laser beam 21 photographed in the photographing step ST5 approaches the aberration component of the laser beam 21 that results in an ideal processing result.

[0104] When the operator determines that the difference between the XZ plane images 500, 501 and the YZ plane images 600, 601 is below the prescribed ratio (step ST8: Yes), the correction method ends. In this way, in the step ST8, regarding the result of the comparison step ST7, if the difference between the XZ plane images 500, 501 and the YZ plane images 600, 601 is below the prescribed ratio, the phase pattern displayed on the display unit 241, that is, the laser beam 21 irradiated to the work 200 is acceptable, and if the difference in at least one of the XZ plane images 500, 501 and the YZ plane images 600, 601 is larger than the prescribed ratio, the correction of the phase pattern, that is, the correction of the XY plane image 400 as the spot shape of the laser beam 21 is performed again by returning to the laser beam irradiation step ST4 via the determination step ST9, the step ST10.

[0105] In addition, in the correction method of the first embodiment, when the value of one Zernike coefficient is changed to a prescribed value to adjust to approach an ideal value in the step ST10, the aberration corresponding to the Zernike coefficient other than the Zernike coefficient whose value is changed among the aberrations included in the XY plane image 400 acquired by the beam analyzer 28 in the photographing step ST5 also changes. Therefore, in the correction method of the first embodiment, the laser beam irradiation step ST4, the photographing step ST5, the comparison step ST7, the step ST8, the determination step ST9, and the step ST10 are repeatedly performed, and the value of the Zernike coefficient is changed one by one until it is determined in the step ST8 that the difference between the XZ plane images 500, 501 and the YZ plane images 600, 601 is below the prescribed ratio.

[0106] Therefore, in the correction method of the first embodiment, the laser beam irradiation step ST4, the photographing step ST5, the comparison step ST7, the step ST8, the determination step ST9, and the step ST10 are repeatedly performed until it is determined in the step ST8 that the difference of both the XZ plane image 500, 501 and the YZ plane image 600, 601 is below the prescribed ratio, and thereby the phase pattern displayed on the display portion 241 of the spatial light modulator 24 is changed so that the XZ plane image 500 or the YZ plane image 600 formed by the image forming step ST6 coincides with the XZ plane image 501 or the YZ plane image 601 formed in accordance with the ideal XY plane image 401 of the reflected light 212 of the laser beam 21 which obtains the ideal processing result.

[0107] As explained above, in the correction method of the first embodiment, in the comparison step ST7, at least one of the action of superimposing the XZ plane image 500, 501 on the display unit 110 and the action of superimposing the YZ plane image 600, 601 on the display unit 110 is performed, and therefore in the step ST8, it is possible to easily determine whether the difference of at least one of the XZ plane image 500, 501 and the YZ plane image 600, 601 is below the prescribed ratio.

[0108] Further, in the correction method of the first embodiment, when it is determined in the step ST8 that the difference of at least one of the XZ plane image 500, 501 and the YZ plane image 600, 601 is larger than the prescribed ratio, at least the XY plane image 400 is displayed on the display unit 110 in the determination step ST9, and the operator determines the aberration of the XY plane image 400 which is most different from the ideal XY plane image 401. Therefore, in the correction method of the first embodiment, it is possible to suppress the working hours required for correcting the aberration of the laser beam 21 to the aberration of the laser beam 21 which obtains the ideal processing result at the processing point. As a result, in the correction method of the first embodiment, it is possible to suppress the working hours required for correcting the spot shape of the laser beam 21.

[0109] In addition, in the correction method of the first embodiment, at least one of the XZ plane images 500, 501 and the YZ plane images 600, 601 is displayed on the display unit 110 at step ST8, and it is possible to easily determine whether or not the difference in at least one of them is below the prescribed ratio, at least the XY plane image 400 is displayed on the display unit 110 at the determination step ST9, and the operator determines the aberration of the XY plane image 400 that is the largest difference from the ideal XY plane image 401. In addition, in the correction method of the first embodiment, the laser beam irradiation step ST4, the photographing step ST5, the comparison step ST7, the step ST8, the determination step ST9, and the step ST10 are repeatedly performed until it is determined at the step ST8 that the differences in both the XZ plane images 500, 501 and the YZ plane images 600, 601 are below the prescribed ratio. Therefore, in the correction method of the first embodiment, it is possible to make the aberration of the laser beam 21 close to the aberration of the laser beam 21 that obtains the ideal processing result at the processing point. As a result, in the correction method of the first embodiment, it is possible to suppress the machine error of the processing device in the spot shape of the laser beam 21.

[0110] Therefore, the correction method of the first embodiment has the effects that it is possible to suppress the working hours required for the correction of the spot shape of the laser beam 21, and it is possible to reduce the machine error of the processing device in the laser beam 21 irradiated to the processed object 200.

[0111] 〔Second Embodiment〕

[0112] A correction method of a spot shape of a laser beam according to a second embodiment of the present application will be described with reference to the drawings. Figure 15 is a perspective view showing a configuration example of a laser processing device that implements the correction method of the spot shape of the laser beam according to the second embodiment. Figure 16 is a view for explaining a configuration of a laser beam irradiation unit of the laser processing device shown in Figure 15 . In addition, in Figure 15 and Figure 16 , the same reference numerals are attached to the same parts as those of the first embodiment, and the explanation is omitted.

[0113] A laser processing device 1-2 that implements a correction method of a spot shape of a laser beam according to the second embodiment (hereinafter referred to as the correction method) is the same as the first embodiment except that an image forming section 101-2 and a storage section 103-2 are additionally provided and a control section 100 has a determination section 104.

[0114] The storage section 103-2 of the control section 100 of the laser processing apparatus 1-2 that implements the correction method of the second embodiment stores, in the storing step ST1, in addition to the function of the first embodiment, ideal values of the Zernike coefficients of the reflected light 212 of the laser beam 21 that result in an ideal processing result. In addition, the phase pattern generating section 102 of the control section 100 of the laser processing apparatus 1-2 that implements the correction method of the second embodiment generates, in the storing step ST1, in addition to the function of the first embodiment, a phase pattern that contains a prescribed aberration component, and generates Figure 17 to Figure 30 the aberration-containing XY plane images 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714 shown in the drawing, and stores them in the storage section 103-2.

[0115] These aberration-containing XY plane images 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714 are XY plane images of the reflected light 212 that contain aberrations, which are generated by photographing the laser beam 21 whose Zernike coefficients corresponding to each aberration are a prescribed value or more, using the beam analyzer 28.

[0116] In this way, the storage section 103-2 of the control section 100 of the laser processing apparatus 1-2 that implements the correction method of the second embodiment stores, in the storing step ST1, the aberration-containing XY plane images 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, so that, with respect to the ideal XY plane image 401 of the shape and the spatial intensity distribution of the reflected light 212 of the laser beam 21 that results in an ideal processing result at the processing point in the processing operation, it is stored what kind of aberration component is contained in the XY plane image 400 that is acquired by the photographing step ST5.

[0117] Figure 17 is a drawing that shows an XY plane image of the reflected light whose Zernike coefficients corresponding to the astigmatism aberration 0° are a prescribed value or more. Figure 18 is a drawing that shows an XY plane image of the reflected light whose Zernike coefficients corresponding to the astigmatism aberration 90° are a prescribed value or more.

[0118] Figure 19 is a drawing that shows an XY plane image of the reflected light whose Zernike coefficients corresponding to the astigmatism aberration +45° are a prescribed value or more. Figure 20 is a drawing that shows an XY plane image of the reflected light whose Zernike coefficients corresponding to the astigmatism aberration -45° are a prescribed value or more.

[0119] Figure 21is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to coma +X is a value or more than a prescribed value. Figure 22 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to coma -X is a value or more than a prescribed value.

[0120] Figure 23 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to coma +Y is a value or more than a prescribed value. Figure 24 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to coma -Y is a value or more than a prescribed value.

[0121] Figure 25 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to spherical aberration + is a value or more than a prescribed value. Figure 26 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to spherical aberration - is a value or more than a prescribed value.

[0122] Figure 27 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to trefoil aberration +X is a value or more than a prescribed value. Figure 28 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to trefoil aberration -X is a value or more than a prescribed value.

[0123] Figure 29 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to trefoil aberration +Y is a value or more than a prescribed value. Figure 30 is a graph showing an XY plane image of reflected light in which the Zernike coefficient corresponding to trefoil aberration -Y is a value or more than a prescribed value.

[0124] The determination section 104 of the control section 100 of the laser processing apparatus 1-2 that implements the correction method of the second embodiment, in the comparison step ST7, calculates the sum of the differences between the XZ plane image 500 of the image formed by the image formation step ST6 and the XZ plane image 501 of the ideal XY plane image 401 (in Figure 13 part, shown with parallel diagonal lines), and the sum of the differences between the YZ plane image 600 of the image formed by the image formation step ST6 and the YZ plane image 601 of the ideal XY plane image 401 (in Figure 14(illustrated in part by parallel diagonal lines). Next, the determination section 104 of the control section 100 of the laser processing apparatus 1-2 calculates, in the comparison step ST7, the sum of the difference between the XZ plane image 500 and the ideal XY plane image 401 and the difference between the YZ plane image 600 and the ideal XY plane image 401. Thus, in the correction method of the second embodiment, the determination section 104 calculates the above sum and compares the XZ plane image 500 and the YZ plane image 600 with the XZ plane image 501 and the YZ plane image 601 in the comparison step ST7.

[0125] In the step ST8, the determination section 104 of the control section 100 of the laser processing apparatus 1-2 determines whether the sum calculated by the comparison step ST7 is below a predetermined prescribed value and determines whether the difference between the XZ plane images 500, 501 and the YZ plane images 600, 601 is below a prescribed ratio. In the step ST8, when the determination section 104 of the control section 100 of the laser processing apparatus 1-2 determines that the sum calculated by the comparison step ST7 is greater than the predetermined prescribed value, it determines that the difference between the XZ plane images 500, 501 and the YZ plane images 600, 601 is greater than the prescribed ratio (step ST8: No), and proceeds to the determination step ST9. In addition, in the step ST8, when the determination section 104 of the control section 100 of the laser processing apparatus 1-2 determines that the sum calculated by the comparison step ST7 is below the predetermined prescribed value (step ST8: Yes), the correction method ends.

[0126] In the judgment step ST9, the judgment section 104 of the control section 100 of the laser processing apparatus 1-2 calculates the plane image most similar to the XY plane image 400 among the aberration- containing XY plane images 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714 stored in the storage section 103-2. The judgment section 104, for example, performs image processing such as pattern matching on each of the aberration-containing XY plane images 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714 and the XY plane image 400, and calculates the plane image most similar to the XY plane image 400 as the plane image similar to the XY plane image 400. The judgment section 104 judges the aberration- containing XY plane image similar to the XY plane image 400 as the aberration having the largest difference from the ideal XY plane image 401 of the XY plane image 400. In this way, in the second embodiment, the judgment section 104 calculates the plane image most similar to the XY plane image 400 among the aberration- containing XY plane images 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, and judges the aberration having the largest difference from the ideal XY plane image 401 of the XY plane image 400, thereby determining what kind of aberration component the XY plane image 400 contains.

[0127] In the step ST10, the judgment section 104 of the control section 100 of the laser processing apparatus 1-2 changes the value of the Zernike coefficient corresponding to the aberration component contained in the plane image most similar to the XY plane image 400 among the aberration- containing XY plane images 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714 to a value close to the ideal value from a value prescribed by the change. In addition, the function of the judgment section 104 is realized by an arithmetic processing device performing arithmetic processing according to a computer program stored in a storage device.

[0128] In the correction method of the second embodiment, in the comparison step ST7, the sum of the difference between the XZ plane images 500 and 501 and the sum of the difference between the YZ plane images 600 and 601 are calculated, and in the step ST8, it is determined whether the sum is equal to or less than a predetermined prescribed value, and thus it is possible to easily determine whether the difference between the XZ plane images 500, 501 and the YZ plane images 600, 601 is equal to or less than a prescribed ratio.

[0129] In addition, in the correction method of the second embodiment, in the judgment step ST9, the plane image most similar to the XY plane image 400 is calculated among the XY plane images 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714 containing aberrations stored in the storage section 103-2, and the aberration having the largest difference from the ideal XY plane image 401 of the XY plane image 400 is determined. As a result, in the correction method of the second embodiment, as in the first embodiment, the man-hours required for the correction of the spot shape of the laser beam 21 can be suppressed.

[0130] In addition, in the correction method of the second embodiment, in the step ST8, since it is determined whether the above sum is below the predetermined prescribed value, it is possible to easily determine whether the differences of the XZ plane images 500, 501 and the YZ plane images 600, 601 are below the prescribed ratio, in the judgment step ST9, the plane image most similar to the XY plane image 400 is calculated among the XY plane images 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714 containing aberrations, and the aberration having the largest difference from the ideal XY plane image 401 is determined. In addition, in the correction method of the second embodiment, the laser beam irradiation step ST4, the photographing step ST5, the comparison step ST7, the step ST8, the judgment step ST9, and the step ST10 are repeatedly performed until it is determined in the step ST8 that the differences of the XZ plane images 500, 501 and the YZ plane images 600, 601 are below the prescribed ratio. As a result, in the correction method of the second embodiment, it is possible to make the aberration of the laser beam 21 close to the aberration of the laser beam 21 that results in an ideal machining result, as in the first embodiment, the mechanical error of the machining device with respect to the spot shape of the laser beam 21 can be suppressed.

[0131] Therefore, in the correction method of the second embodiment, as in the first embodiment, the following effects are exerted: the man-hours required for the correction of the spot shape of the laser beam 21 can be suppressed, and the mechanical error of the machining device with respect to the laser beam 21 irradiated to the work 200 can be reduced.

[0132] In addition, in the second embodiment, in the present application, the determination section 104 of the control section 100 of the laser machining device 1-2 can determine what kind of aberration component is included in the XY plane image 400 using machine learning (AI: Artificial intelligence) in the judgment step ST9.

[0133] (Modified Example)

[0134] A laser processing apparatus according to a modification of the first embodiment and the second embodiment of the present application will be described with reference to the drawings. Figure 31 is a perspective view showing a configuration example of the laser processing apparatus which implements the correction method of the spot shape of the laser beam of the modification of the first embodiment and the second embodiment. In addition, in Figure 31 , the same reference numerals are assigned to the same parts as those of the first embodiment and the description thereof is omitted.

[0135] As shown in Figure 31 , the laser processing apparatus 1-1 of the modification is the same as the first embodiment except that the concave mirror 25 is provided at a prescribed position on the second moving plate 16 and the condensing lens 23 of the laser beam irradiation unit 20 and the reflecting surface 252 of the concave mirror 25 on the second moving plate 16 are opposed to each other in the Z-axis direction in the concave mirror arrangement step ST2.

[0136] The correction method of the spot shape of the laser beam of the modification is the same as the first embodiment and has the effects that the man-hours required for the correction of the spot shape of the laser beam 21 can be suppressed and the mechanical error between the processing apparatuses of the laser beam 21 irradiated to the work 200 can be reduced. In addition, in the present application, the image forming section 101 and the storage section 103 of the laser processing apparatus 1-1 which implements the correction method of the spot shape of the laser beam of the modification can have the same functions as those of the second embodiment and the control section 100 can have the same determination section 104 as that of the second embodiment.

[0137] In addition, the present application is not limited to the above-described embodiments. That is, various modifications can be made within the scope of the gist of the present application. In addition, in the present application, in the case where the ideal XY plane image 401 of the reflected light 212 of the laser beam 21 contains a certain aberration of a prescribed value or more, a method in which the XY plane image 400 is compared with the XY plane image containing the aberration can be used using the XY plane image in which the difference of the Zernike coefficient corresponding to the aberration possessed by the ideal XY plane image 401 is stored as the aberration of a prescribed value.

Claims

1. A method for correcting the spot shape of a laser beam, wherein the spot shape of a laser beam focused by a condenser lens is corrected in a laser processing device. This laser processing device has the following features: A chuck table having a retaining surface that holds the workpiece. A laser beam irradiation unit that irradiates a laser beam onto the workpiece held on the chuck table; and Control Department The laser beam irradiation unit includes: Laser oscillator; The focusing lens, positioned opposite the holding face, focuses the laser beam emitted from the laser oscillator; and A spatial light modulator is disposed between the laser oscillator and the focusing lens. Its features are, The method for correcting the spot shape of this laser beam has the following steps: The concave mirror configuration step involves positioning a concave mirror with a spherical reflective surface opposite to the focusing lens of the laser beam irradiation unit. The focus positioning step, after the concave mirror configuration step, positions the focusing point of the condenser lens at the focal point of the concave mirror. The laser beam irradiation step involves activating the laser oscillator to irradiate the concave mirror with a laser beam focused by the condenser lens. The shooting process involves capturing the reflected light from the concave mirror using a shooting unit. The image forming step forms an XZ plane image or a YZ plane image based on the XY plane image representing the shape and intensity distribution of the laser beam captured by the imaging step; as well as The comparison step compares the image formed through this image formation step with an XZ-plane image or a YZ-plane image of a laser beam having an ideal shape and intensity distribution. The phase pattern displayed on the display of the spatial light modulator is changed so that the XZ plane image or YZ plane image formed by the image forming step is consistent with the XZ plane image or YZ plane image of the laser beam having an ideal shape and intensity distribution.

2. The method for correcting the spot shape of a laser beam according to claim 1, characterized in that, The laser beam spot shape correction method also includes the following judgment step: determining what aberration components are contained in the laser beam image captured through this imaging step. The phase pattern, which eliminates the aberration components determined through this judgment step, is displayed on the display section of the spatial light modulator.

3. The method for correcting the spot shape of a laser beam according to claim 1, characterized in that, The method for correcting the spot shape of the laser beam also includes the following steps: The judgment step involves determining what aberration components are present in the laser beam captured through this imaging step; and The storage step involves storing the aberration components contained in the laser beam, which has an ideal shape and intensity distribution. The phase pattern displayed on the display of the spatial light modulator is changed so that the aberration components of the laser beam captured by the imaging step are consistent with the aberration components of the ideal laser beam.

4. The method for correcting the spot shape of a laser beam according to claim 1, characterized in that, In this comparison step, if the difference between the compared images is below a specified ratio, then the comparison is considered successful. If the difference between the compared images is greater than the specified ratio, the spot shape is corrected again.

5. The method for correcting the spot shape of a laser beam according to claim 1, characterized in that, The concave mirror is mounted within the frame of the chuck worktable.

6. The method for correcting the spot shape of a laser beam according to claim 1, characterized in that, The concave mirror is mounted on the moving plate of the moving unit of the laser processing device.

7. The method for correcting the spot shape of a laser beam according to claim 1, characterized in that, In this laser beam irradiation step, the laser beam passes directly from the focusing lens to the concave mirror.

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