Laser processing equipment

Abstract

To provide a laser processing device capable of quickly detecting an abnormality of a spatial light modulator even during processing.SOLUTION: A laser processing device includes: a laser beam irradiation unit 20 including an oscillator 22, a condenser 23 and a spatial light modulator 24 which modulates and emits an incident laser beam 21 in response to a phase pattern displayed on a display unit 241; a control unit which displays, in an area to which the laser beam 21 of a display unit 241 strikes, a phase pattern including a processing pattern displayed in an area incident on an incidence pupil surface of the condenser 23 and a change detection pattern which surrounds the processing pattern and is displayed in an area not incident on the incidence pupil surface of the condenser 23; a light detection unit 30 for detecting an intensity of the laser beam 21 modulated by the change detection pattern at the spatial light modulator 24; and a determination unit for determining whether or not the spatial light modulator 24 is normally operating based on the intensity of the laser beam 21.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] A processing method for manufacturing semiconductor devices is known in which the focal point of a laser beam is positioned inside a wafer, the laser beam is irradiated along streets (planned dividing lines) to form a modified layer, and the wafer is divided by applying an external force (see Patent Document 1). In a laser processing apparatus that realizes the above-mentioned processing method, a laser beam emitted from an oscillator is modulated by a spatial light modulator, and then focused by a focusing lens to be irradiated onto the wafer. In this laser processing apparatus, if the spatial light modulator does not operate normally due to a defect or abnormality, the laser beam will not be modulated appropriately, which may cause processing defects.

[0003] Therefore, various methods have been proposed to detect malfunctions of spatial light modulators. For example, Patent Document 2 discloses a method of displaying a phase pattern including a marking that modulates a part that does not enter the pupil plane of a condenser lens on a spatial light modulator and acquiring the intensity distribution of the phase pattern including the marking to check the operation. Patent Document 3 discloses a method of checking the operation of a processing device having a first mode for performing laser processing and a second mode different from the first mode by switching the phase pattern displayed on the spatial light modulator while the second mode is being performed, based on the change in intensity before and after the switching. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-051011 A [Patent Document 2] JP 2017-131945 A [Patent Document 3] JP 2018-061994 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, while the method of Patent Document 2 can check for operational abnormalities during processing, it is necessary to acquire two-dimensional intensity distribution, which has the problem of taking a long time for processing.Also, the method of Patent Document 3 has the problem that since it cannot detect abnormalities during laser processing, the entire wafer is processed even if a processing defect occurs during the process.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a laser processing apparatus capable of quickly detecting an abnormality in a spatial light modulator even during processing. [Means for solving the problem]

[0007] In order to solve the above problems and achieve the object, the laser processing apparatus of the present invention comprises a laser beam irradiation unit including an oscillator for emitting a laser beam, a condenser for condensing the laser beam emitted from the oscillator and irradiating the laser beam on a workpiece, and a spatial light modulator disposed between the oscillator and the condenser and having a display unit for displaying a phase pattern and modulating the laser beam incident on the display unit in accordance with the phase pattern and emitting the modulated laser beam, a control unit for controlling the phase pattern to be displayed on the display unit, and a light detection unit for detecting the intensity of the laser beam emitted from the spatial light modulator. and a judgment unit which judges whether the spatial light modulator is operating normally based on the intensity of the laser beam detected by the optical detection unit, wherein the control unit displays a phase pattern in an area of ​​the display unit where the laser beam hits, the phase pattern including a processing pattern which is displayed in an area incident on the entrance pupil plane of the concentrator, and a change detection pattern which surrounds the processing pattern and is displayed in an area not incident on the entrance pupil plane of the concentrator, and the optical detection unit detects the intensity of the laser beam modulated by the change detection pattern and emitted from the display unit.

[0008] In the laser processing apparatus of the present invention, the light detection unit may detect the intensity of the laser beam while the laser beam application unit is irradiating the workpiece with the laser beam.

[0009] In the laser processing apparatus of the present invention, the change detection pattern may modulate the laser beam so that the laser beam travels in a direction different from the direction in which the laser beam modulated by the processing pattern travels.

[0010] Furthermore, in the laser processing apparatus of the present invention, a focusing lens for focusing the laser beam, and an aperture positioned at or near the focal position of the focusing lens are disposed between the spatial light modulator and the collector, and the light detection unit may detect the intensity of the laser beam by receiving reflected light of the laser beam modulated by the change detection pattern, emitted from the spatial light modulator, and irradiated onto the aperture.

[0011] In addition, the laser processing apparatus of the present invention further includes a moving unit that relatively moves the focal point of the laser beam along a plurality of planned division lines set on the workpiece, and in the laser processing apparatus, the control unit may switch at least the change detection pattern among the phase patterns including the processing pattern and the change detection pattern displayed on the display unit of the spatial light modulator each time the laser beam is irradiated along one or more planned division lines.

[0012] In the laser processing apparatus of the present invention, the light detection unit may be a photodiode. Effect of the Invention

[0013] The present invention is capable of detecting abnormalities in a spatial light modulator at high speed even during processing. [Brief description of the drawings]

[0014] [Figure 1]FIG. 1 is a perspective view showing an example of the configuration of a laser processing device according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing an example of a workpiece to be processed by the laser processing apparatus shown in FIG. [Diagram 3] FIG. 3 is a schematic diagram showing a schematic configuration of the laser beam irradiation unit shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing an example of a display section of the spatial light modulator shown in FIG. [Diagram 5] FIG. 5 is a schematic diagram showing a schematic configuration of a laser beam irradiation unit according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 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.

[0016] [Embodiment] First, the configuration of a laser processing device 1 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of the configuration of the laser processing device 1 according to the embodiment. FIG. 2 is a perspective view showing an example of a workpiece 100 to be processed by the laser processing device 1 shown in FIG. 1. FIG. 3 is a schematic diagram showing a schematic configuration of the laser beam irradiation unit 20 shown in FIG. 1. FIG. 4 is a schematic diagram showing an example of a display section 241 of the spatial light modulator 24 shown in FIG. 3.

[0017] In the following description, the X-axis direction is one direction on a horizontal plane. The Y-axis direction is a direction perpendicular to the X-axis direction on a horizontal plane. The Z-axis direction is a direction perpendicular to the X-axis and Y-axis directions. In the laser processing apparatus 1 of the embodiment, the processing feed direction is the X-axis direction, the indexing feed direction is the Y-axis direction, and the focal point position adjustment direction is the Z-axis direction.

[0018] The laser processing device 1 includes a holding table 10, a laser beam irradiation unit 20, a light detection unit 30 (see FIG. 3), an imaging unit 31, a moving unit 60, an imaging unit 70, an input means 80, a control unit 90, and a determination unit 91. The laser processing device 1 according to the embodiment is a device that processes the workpiece 100, which is a processing target, by irradiating the workpiece 100 with a laser beam 21. The processing of the workpiece 100 by the laser processing device 1 is, for example, a modified layer forming process that forms a modified layer 106 (see FIG. 3) inside the workpiece 100 by stealth dicing, a groove processing that forms a groove on the surface 102 of the workpiece 100, or a cutting process that cuts the workpiece 100 along a planned division line 103. In the embodiment, a configuration for forming a modified layer 106 on the workpiece 100 will be described.

[0019] The workpiece 100 is a wafer such as a disk-shaped semiconductor device wafer or an optical device wafer, using, for example, silicon (Si), sapphire (Al2O3), gallium arsenide (GaAs), silicon carbide (SiC), lithium tantalate (LiTa3), or the like as a substrate 101 (see FIG. 2). Note that, although the workpiece 100 is disk-shaped in the embodiment, it does not have to be disk-shaped in the present invention. The workpiece 100 is transported and processed in a state in which it is supported within an opening of the frame 110, with, for example, an annular frame 110 attached thereto and a tape 111 having a diameter larger than the outer diameter of the workpiece 100 attached to the back surface 105 of the workpiece 100.

[0020] 2, the workpiece 100 has planned division lines 103 set in a grid pattern on a surface 102 of a substrate 101, and devices 104 formed in areas partitioned by the planned division lines 103. The devices 104 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integrations), or image sensors such as CCDs (Charge Coupled Devices) or CMOSs ​​(Complementary Metal Oxide Semiconductors).

[0021] In the embodiment, a modified layer 106 (see FIG. 3) is formed on the workpiece 100 along the planned dividing lines 103. The workpiece 100 is divided into individual devices 104 along the modified layer 106 formed on the planned dividing lines 103, and is singulated into chips. Note that, although the chips are square-shaped in the embodiment, they may be rectangular-shaped in the present invention.

[0022] The holding table 10 shown in FIG. 1 etc. holds the workpiece 100 on a holding surface 11. The holding surface 11 is a disk shape made of porous ceramics or the like. In the embodiment, the holding surface 11 is a plane parallel to the horizontal direction. The holding surface 11 is connected to a vacuum suction source, for example, via a vacuum suction path. The holding table 10 suction-holds the workpiece 100 placed on the holding surface 11. A plurality of clamps 12 are arranged around the holding table 10 to clamp an annular frame 110 that supports the workpiece 100.

[0023] The holding table 10 is rotated around an axis parallel to the Z-axis direction by a rotating unit 13. The rotating unit 13 is supported by an X-axis direction moving plate 14. The rotating unit 13 and the holding table 10 are moved in the X-axis direction by a processing feed unit 61, which will be described later, via the X-axis direction moving plate 14. The rotating unit 13 and the holding table 10 are moved in the Y-axis direction by an indexing feed unit 62, which will be described later, via the X-axis direction moving plate 14, the processing feed unit 61, and the Y-axis direction moving plate 15.

[0024] The laser beam irradiation unit 20 is a unit that irradiates a laser beam 21 onto a workpiece 100 held on the holding surface 11 of the holding table 10. Of the laser beam irradiation unit 20, at least a condenser 23 (see FIG. 3) is supported by a focusing point position adjustment unit 63 (described later) that is installed on a pillar 3 erected from the main body 2 of the laser processing apparatus 1. As shown in FIG. 3, the laser beam irradiation unit 20 includes an oscillator 22, a condenser 23, a spatial light modulator 24, a polarizing plate 25, a focusing lens 26, an aperture 27, a relay lens 28, and a mirror 29.

[0025] The oscillator 22 emits a laser beam 21 having a predetermined wavelength for processing the workpiece 100. The laser beam 21 irradiated by the laser beam irradiation unit 20 is a laser beam having a wavelength that is transparent or absorbent to the workpiece 100, and in an embodiment in which modified layer formation processing is performed, is a laser beam having a transparent wavelength.

[0026] The condenser 23 is a condensing lens that condenses the laser beam 21 emitted from the oscillator 22 onto the workpiece 100 held on the holding surface 11 of the holding table 10, and irradiates the workpiece 100. The condenser 23 condenses the laser beam 21 modulated by the spatial light modulator 24 onto the workpiece 100. The focal point 211 of the laser beam 21 condensed by the condenser 23 is positioned inside the workpiece 100 in the modified layer forming process of the embodiment. In the example shown in FIG. 3, the back surface 105 side of the workpiece 100 is held on the holding table 10 and the laser beam 21 is irradiated from the front surface 102 side, but in the present invention, the front surface 102 side may be held on the holding table 10 and the laser beam 21 may be irradiated from the back surface 105 side.

[0027] The spatial light modulator 24 is provided between the oscillator 22 and the condenser 23. The spatial light modulator 24 modulates the incident laser beam 21 by electrically controlling the spatial distribution, such as the amplitude, phase, and polarization, of the laser beam 21 oscillated from the oscillator 22. In the embodiment, the spatial light modulator 24 reflects and outputs the laser beam 21, but in the present invention, the spatial light modulator 24 may transmit and output the laser beam 21.

[0028] The spatial light modulator 24 has a display unit 241. As shown in Fig. 4, the display unit 241 displays a predetermined phase pattern 242. The spatial light modulator 24 modulates the laser beam 21 incident on the display unit 241 according to the phase pattern 242 and emits the modulated laser beam 21. The spatial light modulator 24 adjusts the output of the laser beam 21 irradiated to the workpiece 100 by displaying the phase pattern 242 on the display unit 241. The phase pattern 242 includes a processing pattern 243 and a change detection pattern 244.

[0029] The processing pattern 243 is displayed in a region 212 of the display unit 241 where the laser beam 21 hits and where the laser beam 21 is incident on the entrance pupil plane of the condenser 23. The region where the laser beam 21 is incident on the entrance pupil plane of the condenser 23 refers to, for example, a region where the laser beam 21 reflected in the region passes through the opening of the aperture 27 and where the central portion of the laser beam 21 is irradiated.

[0030] The change detection pattern 244 surrounds the processing pattern 243 in the region 212 of the display unit 241 where the laser beam 21 hits, and is displayed in a region that does not enter the entrance pupil plane of the condenser 23. The region that does not enter the entrance pupil plane of the condenser 23 refers to, for example, a region where the laser beam 21 reflected in that region is irradiated around the opening of the aperture 27, that is, where the outer edge of the laser beam 21 is irradiated. The change detection pattern 244 modulates the laser beam 21, for example, so that the laser beam 21 travels in a direction different from the direction in which the laser beam 21 modulated by the processing pattern 243 travels.

[0031] 4, the area 212 hit by the laser beam 21 is depicted so that its outer edge coincides with the outer periphery of the change detection pattern 244, but as long as it at least overlaps with the change detection pattern 244, the outer edge may be larger or smaller than the outer periphery of the change detection pattern 244. Furthermore, the change detection pattern 244 may be displayed on the entire surface of the display unit 241.

[0032] 3, the polarizing plate 25 is provided between the oscillator 22 and the spatial light modulator 24. The polarizing plate 25 polarizes the laser beam 21 oscillated from the oscillator 22 into light in a specific direction.

[0033] The focusing lens 26 is disposed between the spatial light modulator 24 and the condenser 23. The focusing lens 26 focuses the laser beam 21. In the embodiment, the laser beam 21 transmitted through the focusing lens 26 is focused and irradiated toward the aperture 27, where a part of the laser beam 21 is blocked and a part of the laser beam passes through the focusing lens 26. Of the laser beam 21 transmitted through the focusing lens 26, the laser beam 21 modulated by the processing pattern 243 is focused toward the opening of the aperture 27 and passes through the opening. Of the laser beam 21 transmitted through the focusing lens 26, the laser beam 21 modulated by the change detection pattern 244 is reflected by the aperture 27 and enters the light detection unit 30 as reflected light 213.

[0034] The aperture 27 is disposed between the spatial light modulator 24 and the condenser 23. The aperture 27 is positioned at or near the focal position of the focusing lens 26. The laser beam 21 that has been transmitted through the focusing lens 26 and focused is incident on the aperture 27. The aperture 27 passes the laser beam 21 that has been modulated by the processing pattern 243 in the spatial light modulator 24. The aperture 27 reflects the laser beam 21 that has been modulated by the change detection pattern 244 in the spatial light modulator 24. The opening of the aperture 27 may be circular or rectangular.

[0035] The relay lens 28 is disposed between the spatial light modulator 24 and the condenser 23. The relay lens 28 transmits the laser beam 21, which has been focused by the focusing lens 26 and passed through the aperture 27, to a mirror 29.

[0036] The mirror 29 reflects the laser beam 21 toward the workpiece 100 held on the holding surface 11 of the holding table 10. In the embodiment, the mirror 29 reflects the laser beam 21 that has passed through the relay lens 28 toward the condenser 23.

[0037] The light detection unit 30 detects the received light. The light detection unit 30 detects, for example, the intensity of the laser beam 21 emitted from the spatial light modulator 24. More specifically, the light detection unit 30 detects the intensity of the laser beam 21 modulated by the change detection pattern 244 and emitted from the display unit 241. In the embodiment, the light detection unit 30 detects the intensity of the laser beam 21 by receiving reflected light 213 of the laser beam 21 irradiated to the aperture 27.

[0038] Here, as described above, when the laser beam 21 is irradiated onto the workpiece 100, the laser beam irradiating unit 20 modulates the laser beam 21 incident on the processing pattern 243 by the spatial light modulator 24 so that it is incident on the entrance pupil plane of the condenser 23 to process the workpiece 100 under desired processing conditions, and modulates the laser beam 21 incident on the change detection pattern 244 so that it is incident on the light detection unit 30. In other words, while the laser beam irradiating unit 20 is irradiating the workpiece 100 with the laser beam 21, the light detection unit 30 detects the intensity of the laser beam 21 irradiated onto the change detection pattern 244 and modulated.

[0039] The light detection unit 30 is, for example, a photodiode. The photodiode outputs a voltage value that changes depending on the amount of light of the received laser beam 21 to the control unit 90. The light detection unit 30 is not limited to a photodiode, and may be, for example, an imaging unit equipped with an imaging element such as a CCD imaging element or a CMOS imaging element, or a power meter.

[0040] The imaging unit 31 captures an image of a processing point (focus point 211) by the laser beam 21 irradiated on the workpiece 100 held on the holding table 10. The imaging unit 31 includes, for example, a CCD camera. The imaging unit 31 may be common to the imaging unit 70 described below.

[0041] The moving unit 60 shown in Fig. 1 is a unit that relatively moves a focal point 211 (see Fig. 3) of the laser beam 21 along a plurality of planned division lines 103 set on the workpiece 100. The moving unit 60 includes a processing feed unit 61, an indexing feed unit 62, and a focal point position adjustment unit 63.

[0042] The processing feed unit 61 is a unit that relatively moves the holding table 10 and the focal point 211 (see FIG. 3) of the laser beam irradiation unit 20 in the X-axis direction, which is the processing feed direction. In the embodiment, the processing feed unit 61 moves the holding table 10 in the X-axis direction. In the embodiment, the processing feed unit 61 is installed on the device body 2 of the laser processing device 1. The processing feed unit 61 supports the X-axis moving plate 14 so that it can be freely moved in the X-axis direction.

[0043] The indexing feed unit 62 is a unit that relatively moves the holding table 10 and the focal point 211 (see FIG. 3) of the laser beam irradiation unit 20 in the Y-axis direction, which is the indexing feed direction. In the embodiment, the indexing feed unit 62 moves the holding table 10 in the Y-axis direction. In the embodiment, the indexing feed unit 62 is installed on the device body 2 of the laser processing device 1. The indexing feed unit 62 supports the Y-axis moving plate 15 so that it can be moved freely in the Y-axis direction.

[0044] The focal point position adjustment unit 63 is a unit that relatively moves the holding table 10 and the focal point 211 (see FIG. 3) of the laser beam application unit 20 in the Z-axis direction, which is the focal point position adjustment direction. In the embodiment, the focal point position adjustment unit 63 moves at least the condenser 23 of the laser beam application unit 20 in the Z-axis direction. In the embodiment, the focal point position adjustment unit 63 is installed on a pillar 3 erected from the device body 2 of the laser processing device 1. The focal point position adjustment unit 63 supports at least the condenser 23 of the laser beam application unit 20 so that it can be moved freely in the Z-axis direction.

[0045] In the embodiment, each of the processing feed unit 61, the indexing feed unit 62, and the focal point position adjustment unit 63 includes a known ball screw, a known pulse motor, and a known guide rail. The ball screw is provided so as to be rotatable about its axis. The pulse motor rotates the ball screw about its axis. The guide rail of the processing feed unit 61 supports the X-axis moving plate 14 so as to be movably in the X-axis direction. The guide rail of the processing feed unit 61 is provided fixedly to the Y-axis moving plate 15. The guide rail of the indexing feed unit 62 supports the Y-axis moving plate 15 so as to be movably in the Y-axis direction. The guide rail of the indexing feed unit 62 is provided fixedly to the device body 2. The guide rail of the focal point position adjustment unit 63 supports at least the condenser 23 of the laser beam irradiation unit 20 so as to be movably in the Z-axis direction. The guide rail of the focal point position adjustment unit 63 is provided so as to be fixedly to the column 3.

[0046] The imaging unit 70 images the workpiece 100 held on the holding table 10. The imaging unit 70 includes a CCD camera or an infrared camera. The imaging unit 70 is fixed, for example, adjacent to the condenser 23 (see FIG. 2) of the laser beam irradiation unit 20. The imaging unit 70 images the workpiece 100, obtains an image for performing alignment between the workpiece 100 and the laser beam irradiation unit 20, and outputs the obtained image.

[0047] In the embodiment, the input means 80 is a touch panel included in a display device configured by a liquid crystal display device or the like. The input means 80 can receive various operations such as an operator registering processing content information. The input means 80 may be an external input device such as a keyboard.

[0048] The control unit 90 controls each of the above-mentioned components of the laser processing device 1, and causes the laser processing device 1 to execute processing operations and the like on the workpiece 100. The control unit 90 is a computer including an arithmetic processing device as a calculation means, a storage device as a storage means, and an input / output interface device as a communication means. The arithmetic processing device includes, for example, a microprocessor such as a CPU (Central Processing Unit). The storage device has memories such as a HDD (Hard Disk Drive), a ROM (Read Only Memory), or a RAM (Random Access Memory). The arithmetic processing device performs various calculations based on a predetermined program stored in the storage device. The arithmetic processing device outputs various control signals to each of the above-mentioned components via the input / output interface device according to the calculation results, and controls the laser processing device 1.

[0049] The control unit 90 controls the phase pattern 242 to be displayed on the display unit 241 of the spatial light modulator 24. For example, the control unit 90 displays the phase pattern 242 in the region 212 of the display unit 241 where the laser beam 21 hits. The control unit 90 switches at least the change detection pattern 244 out of the phase pattern 242 including the processing pattern 243 and the change detection pattern 244 displayed on the display unit 241 of the spatial light modulator 24, for example, every time the laser beam 21 is irradiated along one or more planned division lines 103. At this time, the change detection pattern 244 is assumed to change the output of the light detection unit 30 received by a predetermined value or more before and after switching. The control unit 90 may switch the change detection pattern 244 by switching from a state in which the change detection pattern 244 is displayed to a state in which the change detection pattern 244 is not displayed.

[0050] The determination unit 91 determines whether or not the spatial light modulator 24 is operating normally based on the intensity of the laser beam 21 detected by the light detection unit 30. The determination unit 91 may be configured as a part of a computer serving as the control unit 90. For example, when the control unit 90 switches the change detection pattern 244 among the phase patterns 242 displayed on the display unit 241, the determination unit 91 determines whether or not the spatial light modulator 24 is operating normally based on whether or not the intensity of the laser beam 21 detected by the light detection unit 30 has changed.

[0051] As described above, in the laser processing apparatus 1 according to the embodiment, when the laser beam 21 is irradiated onto the workpiece 100, the laser beam irradiating unit 20 modulates the laser beam 21 incident on the processing pattern 243 by the spatial light modulator 24 so that it is incident on the entrance pupil plane of the condenser 23 to process the workpiece 100 under desired processing conditions, and modulates the laser beam 21 incident on the change detection pattern 244 so that it is incident on the light detection unit 30. That is, in the laser processing apparatus 1, while the laser beam irradiating unit 20 is irradiating the workpiece 100 with the laser beam 21, the light detection unit 30 can detect the intensity of the laser beam 21 irradiated onto the change detection pattern 244 and modulated.

[0052] This makes it possible to quickly detect abnormalities in the spatial light modulator 24 while processing the workpiece 100, making it possible to notice abnormalities even during processing, thereby reducing the possibility of processing the entire workpiece 100 and resulting in a defective chip.

[0053] Furthermore, the control unit 90 may switch at least the change detection pattern 244 out of the phase pattern 242 including the processing pattern 243 and the change detection pattern 244 displayed on the display unit 241 of the spatial light modulator 24 every time the laser beam 21 is irradiated along one or more of the planned division lines 103. At this time, by switching the change detection pattern 244, the output received by the light detection unit 30 is changed by a predetermined value or more, so that the light detection unit 30 can detect the intensity change of the laser beam 21 with higher accuracy, and the determination unit 91 can determine with higher accuracy whether the spatial light modulator 24 is operating normally. Note that in the present invention, for example, the change detection pattern 244 may be switched many times while processing one planned division line 103.

[0054] The present invention is not limited to the above embodiment. In other words, various modifications can be made without departing from the gist of the present invention. For example, the light detection unit 30 does not necessarily have to receive the reflected light 213 reflected by the aperture 27.

[0055] [Modifications] 5 is a schematic diagram showing a schematic configuration of a laser beam irradiation unit 20-1 according to a modified example. The laser beam irradiation unit 20-1 of the modified example differs from the laser beam irradiation unit 20 of the embodiment in that it includes a light detection unit 30-1 instead of the light detection unit 30 arranged to receive the reflected light 213 reflected by the aperture 27.

[0056] Of the laser beam 21, the laser beam 21 modulated by the change detection pattern 244 travels in a direction different from the direction in which the laser beam 21 modulated by the processing pattern 243 travels. Of the laser beam 21 that has passed through the focusing lens 26, the laser beam 21 modulated by the processing pattern 243 is focused toward the opening of the aperture 27 and passes through the opening. Of the laser beam 21 modulated by the change detection pattern 244, light 214 that has passed through the focusing lens 26 is incident on the photodetection unit 30-1. The photodetection unit 30-1 detects the intensity of the laser beam 21 modulated by the change detection pattern 244 by receiving the light 214.

[0057] In this way, the photodetection units 30 and 30-1 may be arranged in any manner as long as they receive the laser beam 21 emitted from the change detection pattern 244 in the spatial light modulator 24.

[0058] Furthermore, as another modified example, for example, the light detection unit may be disposed between the spatial light modulator 24 and the focusing lens 26 in the laser beam irradiation unit. That is, of the laser beam 21 modulated by the spatial light modulator 24, the laser beam 21 modulated by the processing pattern 243 passes through the focusing lens 26 and is focused toward the opening of the aperture 27. Of the laser beam 21 modulated by the spatial light modulator 24, the laser beam 21 modulated by the change detection pattern 244 is incident on the light detection unit. [Explanation of symbols]

[0059] 1 Laser processing equipment 10 Holding table 11 Holding surface 20, 20-1 Laser beam irradiation unit 21 Laser Beam 211 Focus point 212 areas 213 Reflected light 214 light 22 Oscillators 23 Concentrator 24 Spatial Light Modulator 241 Display section 242 Phase Pattern 243 Processing Pattern 244 Change Detection Pattern 25 Polarizing Plate 26 Focusing Lens 27 Aperture 28 Relay Lens 29. Mirror 30, 30-1 Optical detection unit 31 Imaging unit 60 Mobile Units 90 Control section 91 Judgment section 100 Workpiece 102 Surface 103 Division line 105 Back side 106 Modified layer

Claims

1. A laser processing apparatus comprising: An oscillator that emits a laser beam; a condenser that condenses the laser beam emitted from the oscillator and irradiates the laser beam on a workpiece; a spatial light modulator that is disposed between the oscillator and the condenser, has a display unit that displays a phase pattern, and modulates the laser beam incident on the display unit in accordance with the phase pattern and emits the modulated laser beam; A laser beam irradiation unit including: A control unit that controls a phase pattern to be displayed on the display unit; a light detection unit for detecting the intensity of the laser beam emitted from the spatial light modulator; a determination unit that determines whether the spatial light modulator is operating normally based on the intensity of the laser beam detected by the light detection unit; Equipped with The control unit A processing pattern displayed in an area incident on an entrance pupil plane of the collector; a change detection pattern that surrounds the processing pattern and is displayed in an area that is not incident on the entrance pupil plane of the condenser; a phase pattern including the phase pattern is displayed in an area of ​​the display unit where the laser beam strikes; The optical detection unit comprises: The intensity of the laser beam modulated by the change detection pattern and emitted from the display unit is detected. Laser processing equipment.

2. The optical detection unit comprises: The intensity of the laser beam is detected while the laser beam irradiation unit is irradiating the workpiece with the laser beam. The laser processing apparatus according to claim 1.

3. The change detection pattern is The laser beam is modulated so that the laser beam travels in a direction different from a direction in which the laser beam modulated by the processing pattern travels.

3. The laser processing apparatus according to claim 1 or 2.

4. Between the spatial light modulator and the condenser, a focusing lens for focusing the laser beam; an aperture located at or near the focal point of the focusing lens; is provided, The optical detection unit comprises: the intensity of the laser beam is detected by receiving a reflected light of the laser beam modulated by the change detection pattern and emitted from the spatial light modulator to irradiate the aperture. The laser processing apparatus according to any one of claims 1 to 3.

5. a moving unit that relatively moves a focal point of the laser beam along a plurality of planned dividing lines set on the workpiece, The control unit Each time the laser beam is irradiated along one or more of the planned division lines, At least the change detection pattern is switched among phase patterns including the processing pattern and the change detection pattern displayed on the display unit of the spatial light modulator. The laser processing apparatus according to any one of claims 1 to 4.

6. The light detection unit is a photodiode. The laser processing apparatus according to any one of claims 1 to 5.

Images