JP7702319B2 - Laser processing equipment - Google Patents

Description

The present invention relates to a laser processing device.

A processing method is known for manufacturing semiconductor devices in which the focal point of a laser beam is positioned inside a wafer, the 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 device 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.

Recently, in order to shorten the time required for processing, a method has been used in which a spatial light modulator splits a laser beam and processes the material at multiple focusing points (see Patent Document 2). In this type of laser processing device, if the spatial light modulator does not operate normally due to a defect or abnormality, the laser beam will not be split appropriately and the laser beam may be irradiated in an unsplit state, which may cause processing defects.

Therefore, various methods have been proposed to detect malfunctions of spatial light modulators. For example, Patent Document 3 discloses a method of displaying a phase pattern including a marking that modulates a portion of the light that does not enter the pupil plane of the focusing lens on the spatial light modulator, and acquiring the intensity distribution of the phase pattern including the marking to check the operation.

JP 2011-051011 A JP 2011-161491 A JP 2017-131945 A

However, while the method of Patent Document 3 makes it possible to check for operational abnormalities during processing, it has the problem that it requires obtaining a two-dimensional intensity distribution, which takes a long time to process.

The present invention was made in consideration of these problems, and its purpose is to provide a laser processing device that can quickly detect abnormalities in a spatial light modulator.

In order to solve the above problems and achieve the object, the laser processing apparatus of the present invention includes a laser beam irradiation unit including 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 and 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, and a mirror that reflects the laser beam emitted from the spatial light modulator toward the condenser , a light detection unit that receives leakage light of the laser beam that is emitted from the spatial light modulator and transmitted through the mirror without being reflected by the mirror and detects its intensity, and a light detection unit that is disposed between the mirror and the light detection unit. the spatial light modulator comprises a condensing lens which condenses the leaked light toward the light detection unit by being guided by a mirror, a diffusion plate which is disposed between the mirror and the condensing lens and which diffuses the leaked light, and a control unit which controls each of the components, the control unit comprising a pattern control unit which controls a phase pattern to be displayed on the display unit, a memory unit which stores as a reference intensity the intensity of the laser beam detected by the light detection unit when a branching pattern which is the phase pattern for branching a laser beam is displayed on the display unit by the pattern control unit, and a judgment unit which judges whether the spatial light modulator is operating normally or not based on whether the intensity of the laser beam detected by the light detection unit has changed from the reference intensity.

In addition, in the laser processing device of the present invention, a focusing lens that focuses the laser beam and an aperture positioned at or near the focal position of the focusing lens may be disposed between the spatial light modulator and the light detection unit.

In the laser processing device of the present invention, the light detection unit may be a photodiode.

The present invention can quickly detect abnormalities in spatial light modulators.

FIG. 1 is a perspective view showing an example of the configuration of a laser processing device according to an embodiment. FIG. 2 is a perspective view showing an example of a workpiece to be processed by the laser processing apparatus shown in FIG. FIG. 3 is a schematic diagram showing a schematic configuration of the laser beam irradiation unit shown in FIG. FIG. 4 is a schematic diagram showing an example of a phase pattern displayed on the display unit of the spatial light modulator shown in FIG. FIG. 5 is a schematic diagram of a laser beam emitted from a display unit on which the phase pattern shown in FIG. 4 is displayed. FIG. 6 is a schematic diagram showing an abnormal operation of the display unit of the spatial light modulator shown in FIG. FIG. 7 is a schematic diagram of a laser beam emitted from the display unit shown in FIG. FIG. 8 is a schematic diagram showing how the light detection unit shown in FIG. 3 receives a laser beam. FIG. 9 is a schematic diagram showing how a light detection unit receives a laser beam in a laser beam irradiation unit according to a comparative example.

The following describes in detail the form (embodiment) for carrying out the present invention with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. 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 combined as appropriate. Various omissions, substitutions, or modifications of the configuration can be made without departing from the spirit of the present invention.

[Embodiment]
First, the configuration of the laser processing device 1 according to the 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 phase pattern 242 displayed on the display unit 241 of the spatial light modulator 24 shown in FIG. 3. FIG. 5 is a schematic diagram of the laser beam 21 emitted from the display unit 241 on which the phase pattern 242 shown in FIG. 4 is displayed.

In the following description, the X-axis direction is one direction on a horizontal plane. The Y-axis direction is a direction on a horizontal plane that is perpendicular to the X-axis direction. The Z-axis direction is a direction perpendicular to the X-axis and Y-axis directions. In the embodiment of the laser processing device 1, 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.

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 means 31, a moving unit 60, an imaging unit 70, an input means 80, and a control unit 90. The laser processing device 1 according to the embodiment is a device that processes the workpiece 100, which is the 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 process that forms a groove on the surface 102 of the workpiece 100, or a cutting process that cuts the workpiece 100 along the planned division line 103. In the embodiment, a configuration for forming a modified layer 106 on the workpiece 100 will be described.

The workpiece 100 is a wafer such as a disk-shaped semiconductor device wafer or an optical device wafer, with a substrate 101 (see FIG. 2) made of, for example, silicon (Si), sapphire (Al ₂ O ₃ ), gallium arsenide (GaAs), silicon carbide (SiC), or lithium tantalate (LiTa ₃ ). Note that the workpiece 100 is disk-shaped in the embodiment, but may not 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.

As shown in FIG. 2, the workpiece 100 has planned division lines 103 set in a grid pattern on the surface 102 of the 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 Integration), or image sensors such as CCDs (Charge Coupled Devices) or CMOSs (Complementary Metal Oxide Semiconductors).

In the embodiment, the workpiece 100 has a modified layer 106 (see FIG. 3) formed 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.

The holding table 10 shown in FIG. 1 holds the workpiece 100 on the 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 holds the workpiece 100 placed on the holding surface 11 by suction. A plurality of clamps 12 are arranged around the holding table 10 to clamp an annular frame 110 that supports the workpiece 100.

The holding table 10 is rotated around an axis parallel to the Z-axis direction by the rotation unit 13. The rotation unit 13 is supported by the X-axis direction moving plate 14. The rotation unit 13 and holding table 10 are moved in the X-axis direction by the processing feed unit 61 described below via the X-axis direction moving plate 14. The rotation unit 13 and holding table 10 are moved in the Y-axis direction by the indexing feed unit 62 described below via the X-axis direction moving plate 14, the processing feed unit 61, and the Y-axis direction moving plate 15.

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. At least the condenser 23 (see FIG. 3) of the laser beam irradiation unit 20 is supported by a focusing point position adjustment unit 63 (described later) installed on a column 3 erected from the device body 2 of the laser processing device 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. The laser beam irradiation unit 20 also includes a condensing lens 32, a diffuser 33, and a filter 34 between the light detection unit 30 and the mirror 29.

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

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 formation 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.

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 of the amplitude, phase, polarization, etc. of the laser beam 21 emitted 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.

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 phase pattern 242 is displayed in an area 212 of the display unit 241 where the laser beam 21 hits. The spatial light modulator 24 modulates the laser beam 21 incident on the display unit 241 according to the phase pattern 242 and emits it.

In the example shown in FIG. 4, phase pattern 242 is a branching pattern for branching and emitting incident laser beam 21. As shown in FIG. 4, when phase pattern 242, which is a branching pattern, is displayed on display unit 241, laser beam 21 branches into multiple laser beams 21 as shown in FIG. 5.

As shown in FIG. 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 emitted from the oscillator 22 into light in a specific direction.

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 that passes through the focusing lens 26 is focused and irradiated toward the aperture 27, with a portion of the laser beam being blocked and a portion passing through the opening.

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, and a portion of the laser beam 21 passes through the opening 27-1. The aperture 27 passes or partially blocks the laser beam 21 that has been modulated by the phase pattern 242 in the spatial light modulator 24.

As shown in FIG. 5, the laser beam 21 emitted from the display unit 241 displaying the phase pattern 242, which is the branching pattern shown in FIG. 4, branches into multiple beams, and two of the laser beams 21 pass through the opening 27-1 of the aperture 27. The aperture 27, for example, blocks higher-order light generated by the branching pattern. Therefore, when a branching pattern is displayed on the display unit 241 as the phase pattern 242, the higher-order light is blocked by the aperture 27, and the output of the laser beam 21 at the processing point (focus point 211) is lower than when the branching pattern is not displayed. Note that the opening 27-1 of the aperture 27 is not limited to the circular shape shown in FIG. 5, and may be rectangular.

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 the mirror 29.

The mirror 29 reflects the laser beam 21 emitted from the spatial light modulator 24 toward the condenser 23. That is, 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. The mirror 29 also transmits a portion of the laser beam 21 that has passed through the relay lens 28 as leakage light 213.

The optical detection unit 30 detects the received light. For example, the optical detection unit 30 detects the intensity of the laser beam 21 emitted from the spatial light modulator 24. More specifically, the optical detection unit 30 detects the intensity of the laser beam 21 modulated by the phase pattern 242, emitted from the display unit 241, and passed through the aperture 27. In the embodiment, the optical detection unit 30 detects the output of the laser beam 21 modulated by the phase pattern 242 while irradiating the workpiece 100 with the laser beam 21 by receiving leakage light 213 of the laser beam 21 that is not reflected by the mirror 29 and transmitted through the mirror 29.

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.

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

The focusing lens 32 is disposed between the mirror 29 and the light detection unit 30. The focusing lens 32 focuses the leakage light 213 of the laser beam 21 that has passed through the mirror 29 in front of the light detection unit 30.

The diffusion plate 33 is disposed between the mirror 29 and the condenser lens 32. The diffusion plate 33 diffuses the leakage light 213 of the incident laser beam 21, thereby eliminating unevenness in the intensity of the leakage light 213 of the transmitted laser beam 21.

The filter 34 is disposed between the diffusion plate 33 and the condenser lens 32. The filter 34 transmits a portion of the leakage light 213 of the laser beam 21. For example, the filter 34 transmits only the laser beam 21 of the wavelength received by the light detection unit 30, out of the leakage light 213 of the laser beam 21. The filter 34 includes, for example, an ND (Neutral Density) filter. The ND filter is a filter that transmits a certain amount of light without selecting a wavelength in a specific wavelength band.

The moving unit 60 shown in FIG. 1 is a unit that relatively moves the 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.

The processing feed unit 61 is a unit that moves the holding table 10 and the focal point 211 (see FIG. 3) of the laser beam irradiation unit 20 relatively 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 move freely in the X-axis direction.

The indexing feed unit 62 is a unit that moves the holding table 10 and the focal point 211 (see FIG. 3) of the laser beam irradiation unit 20 relatively 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 move freely in the Y-axis direction.

The focal point position adjustment unit 63 is a unit that moves the holding table 10 and the focal point 211 (see FIG. 3) of the laser beam irradiation unit 20 relatively 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 irradiation unit 20 in the Z-axis direction. In the embodiment, the focal point position adjustment unit 63 is installed on a pillar 3 that stands upright 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 irradiation unit 20 so that it can be moved freely in the Z-axis direction.

In the embodiment, the processing feed unit 61, the indexing feed unit 62, and the focal point position adjustment unit 63 each include 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 movable 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 movable 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 movable 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.

The imaging unit 70 captures an image of 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 captures an image of the workpiece 100 to obtain an image for performing alignment between the workpiece 100 and the laser beam irradiation unit 20, and outputs the obtained image.

In an 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 accept various operations such as an operator registering processing content information. The input means 80 may be an external input device such as a keyboard.

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 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. The control unit 90 has a pattern control unit 91, a storage unit 92, and a judgment unit 93.

The pattern control unit 91 controls the phase pattern 242 to be displayed on the display unit 241 of the spatial light modulator 24. For example, the pattern control unit 91 causes the phase pattern 242 to be displayed in the area 212 of the display unit 241 where the laser beam 21 hits. For example, the pattern control unit 91 causes the display unit 241 to display a branching pattern (see FIG. 4), which is the phase pattern 242 for branching the laser beam 21.

The memory unit 92 is included in the storage device of the control unit 90. The memory unit 92 stores the intensity of the laser beam 21 detected by the optical detection unit 30 as a reference intensity when the branching pattern is displayed on the display unit 241 by the pattern control unit 91. In other words, the memory unit 92 acquires and stores the intensity of the laser beam 21 that is irradiated onto the branching pattern and branched (modulated) from the optical detection unit 30.

The determination unit 93 determines whether the spatial light modulator 24 is operating normally based on the intensity of the laser beam 21 detected by the light detection unit 30. More specifically, the determination unit 93 determines whether the intensity of the laser beam 21 detected by the light detection unit 30 has changed from the reference intensity stored in the memory unit 92, and determines whether the spatial light modulator 24 is operating normally based on the determination result.

Next, a method for determining whether the spatial light modulator 24 is malfunctioning will be described. FIG. 6 is a schematic diagram showing an abnormal operation of the display unit 241 of the spatial light modulator 24 shown in FIG. 3. FIG. 7 is a schematic diagram of the laser beam 21 emitted from the display unit 241 shown in FIG. 6.

In the example shown in FIG. 6, when the display unit 241 is operating abnormally, it is unable to display a branch pattern as the phase pattern 242-1, and nothing is displayed in the area 212 (see FIG. 3) where the laser beam 21 is irradiated. Note that in FIG. 6 of this specification, for the sake of explanation, the area where the laser beam 21 is irradiated on the black display unit 241 is depicted in gray, but in reality, the entire display unit 241, including the area where the laser beam 21 is irradiated, is in a black state with nothing displayed.

At this time, as shown in FIG. 7, the laser beam 21 is not branched. When the laser beam 21 is emitted from the branching pattern (phase pattern 242 in FIG. 4) displayed on the display unit 241 in the normal state, the higher-order light is blocked by the aperture 27, whereas when the laser beam 21 is emitted from the display unit 241 that does not display a branching pattern, the higher-order light is not blocked by the aperture 27. Therefore, the output of the laser beam 21 at the processing point (focus point 211) increases, and the intensity of the laser beam 21 detected by the light detection unit 30 increases.

Here, the memory unit 92 stores as a reference intensity the intensity detected by the optical detection unit 30 of the laser beam 21 emitted from the branching pattern (phase pattern 242 in FIG. 4) displayed on the display unit 241 under normal conditions and in which higher-order light is blocked by the aperture 27. When the determination unit 93 determines that the intensity detected by the optical detection unit 30 of the laser beam 21 emitted from the display unit 241 in which no branching pattern is displayed and in which higher-order light is not blocked has changed from the reference intensity, it determines that the spatial light modulator 24 is not operating normally.

Next, the function of the diffusion plate 33 will be described. FIG. 8 is a schematic diagram showing how the optical detection unit 30 shown in FIG. 3 receives the laser beam 21. FIG. 9 is a schematic diagram showing how the optical detection unit 30 receives the laser beam 21 in the laser beam irradiation unit 20-1 according to the comparative example. Note that the filter 34 is not depicted in FIGS. 8 and 9.

As shown in FIG. 8, the leakage light 213 of the laser beam 21 is incident on the diffusion plate 33 in a state where it is branched according to the branching pattern displayed on the display unit 241. The diffusion plate 33 diffuses the incident laser beam 21, causing it to be emitted in a state where the effects of branching have been smoothed out. The focusing lens 32 focuses the leakage light 213 of the laser beam 21, the effects of branching of which have been smoothed out, towards the light detection unit 30.

In contrast, as shown in FIG. 9 of the comparative example, in the laser beam irradiation unit 20-1 that does not have a diffusion plate 33, the leakage light 213 of the laser beam 21 is branched according to the branching pattern displayed on the display unit 241 and enters the condenser lens 32. The condenser lens 32 focuses the laser beam 21 that remains branched toward the light detection unit 30. However, the output of the laser beam 21 detected by the light detection unit 30 may become unstable because the laser beam 21 that remains branched is incident on multiple points on the light receiving surface of the light detection unit 30.

For example, if the light detection unit 30 is a photodiode, the light receiving surface of the photodiode is small, and therefore it may not be possible to receive the laser beam 21 as it is branched. In the laser beam irradiation unit 20 equipped with the diffusion plate 33 of the embodiment, the light detection unit 30 can stably measure the intensity of the laser beam 21.

As described above, in the laser processing device 1 according to the embodiment, when the laser beam irradiation unit 20 irradiates the workpiece 100 with the laser beam 21, the laser beam irradiation unit 20 modulates the laser beam 21 incident on the phase pattern 242 displayed on the display unit 241 of the spatial light modulator 24 in accordance with the phase pattern 242. Specifically, the spatial light modulator 24 displays a branching pattern, which is the phase pattern 242 for branching the laser beam 21, on the display unit 241, and branches and emits the laser beam 21. In addition, the laser processing device 1 includes a light detection unit 30 that detects the intensity of the laser beam 21 emitted from the spatial light modulator 24, and the memory unit 92 of the control unit 90 prestores the intensity of the laser beam 21 branched by the branching pattern.

When an abnormality occurs in the spatial light modulator 24 and the branching pattern is no longer displayed on the display unit 241, for example when no phase pattern 242 is displayed, the output of the laser beam 21 reaching the processing point changes. In the laser processing device 1 of the embodiment, the laser beam 21 is irradiated onto the workpiece 100 while the output of the laser beam 21 emitted from the display unit 241 is detected, and compared with the reference intensity under normal conditions, thereby making it possible to detect an abnormality in the spatial light modulator 24.

This makes it possible to quickly detect abnormalities in the spatial light modulator 24 while one workpiece 100 is being processed, making it possible to notice abnormalities even during processing, thus reducing the possibility of processing the entire workpiece 100 and producing a defective chip.

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, in the laser beam irradiation unit 20 of the embodiment, the leakage light 213 of the laser beam 21, which has been smoothed out by the diffusion plate 33, is condensed by the condenser lens 32 and received by the light detection unit 30, but the leakage light may be transferred as a reduced relay system and received. In addition, the measurement optical system including the diffusion plate 33, the filter 34, and the light detection unit 30 may be tilted to prevent the reflected light of the filter 34 from returning to the imaging means 31 or the oscillator 22. This prevents the reflected light of the filter 34 from returning to the imaging means 31 and affecting the reflectance measurement of the workpiece 100, and also prevents the reflected light of the filter 34 from returning to the oscillator 22 and affecting the oscillation of the laser beam 21.

1 Laser processing device 10 Holding table 11 Holding surface 20, 20-1 Laser beam irradiation unit 21 Laser beam 211 Focusing point 212 Area 213 Leaking light 22 Oscillator 23 Focusing device 24 Spatial light modulator 241 Display unit 242, 242-1 Phase pattern 25 Polarizing plate 26 Focusing lens 27 Aperture 28 Relay lens 29 Mirror 30 Light detection unit 31 Imaging means 32 Focusing lens 33 Diffusion plate 34 Filter 60 Moving unit 61 Processing feed unit 62 Indexing feed unit 90 Control unit 91 Pattern control unit 92 Memory unit 93 Determination unit 100 Workpiece 103 Planned division line 102 Front surface 105 Back surface 106 Modified layer

Claims (3)

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 mirror that reflects the laser beam emitted from the spatial light modulator toward the condenser;
A laser beam irradiation unit including:
a light detection unit that receives leakage light of the laser beam that is emitted from the spatial light modulator and transmitted without being reflected by the mirror, and detects the intensity of the leakage light;
a condenser lens disposed between the mirror and the light detection unit to condense the leaked light toward the light detection unit;
a diffusion plate disposed between the mirror and the condenser lens to diffuse the leaked light;
A control unit for controlling each of the components;
Equipped with
The control unit
A pattern control unit that controls a phase pattern to be displayed on the display unit;
a storage section for storing, as a reference intensity, the intensity of the laser beam detected by the light detection unit when a branch pattern, which is the phase pattern for branching a laser beam, is displayed on the display section by the pattern control section;
a determination unit that determines whether the spatial light modulator is operating normally based on whether the intensity of the laser beam detected by the light detection unit has changed from the reference intensity;
Characterized in that it has
Laser processing equipment. Between the spatial light modulator and the light detection unit,
a focusing lens for focusing the laser beam;
an aperture located at or near the focal point of the focusing lens;
is provided,
The laser processing apparatus according to claim 1 . The light detection unit is a photodiode.
3. The laser processing apparatus according to claim 1 or 2.

Images