KR20230042565A - Laser processing apparatus - Google Patents

Abstract

The present invention provides a laser processing apparatus capable of rapidly detecting abnormality in a spatial light modulator. The laser processing apparatus comprises: a laser beam irradiation unit which is arranged between a laser oscillator and a condenser, and includes a spatial light modulator modulating and emitting a laser beam incident according to a phase pattern displayed on a display part; a light detection unit which detects the intensity of the laser beam; a pattern control part which controls the phase pattern displayed on the display part; a memory part which stores the intensity of the laser beam detected by the light detection unit as a reference intensity when a branching pattern, which is a phase pattern for branching the laser beam on the display part, is displayed; and a determination part which, based on whether the intensity of the laser beam detected by the light detection unit has changed from the reference intensity, determines whether the spatial light modulator is operating normally.

Description

Laser processing device {LASER PROCESSING APPARATUS}

The present invention relates to a laser processing device.

In order to manufacture a semiconductor device, a processing method is known in which a light convergence point of a laser beam is positioned inside a wafer, a modified layer is formed by irradiation along a street (line to be divided), and division is performed by applying an external force (Patent Documents). 1). In the laser processing apparatus realizing the above-described processing method, a laser beam emitted from a laser oscillator is modulated by a spatial light modulator, condensed by a condensing lens, and irradiated onto a wafer.

However, in recent years, in order to shorten the processing time, a method of splitting a laser beam by a spatial light modulator and performing processing at a plurality of converging points has been used (see Patent Document 2). In this laser processing device, if the spatial light modulator does not operate normally due to a defect or abnormality, the laser beam is not properly diverged and the laser beam is irradiated in a state of differential branching, which may cause processing defects.

Accordingly, various methods have been proposed to detect malfunction of the spatial light modulator. For example, in Patent Literature 3, a spatial light modulator displays a phase pattern including a marking that modulates a part that is not incident on the pupil surface of a condensing lens, and obtains an intensity distribution of the phase pattern including the marking. By doing so, a method for confirming an operation is disclosed.

Patent Document 1: Japanese Unexamined Patent Publication No. 2011-051011 Patent Document 2: Japanese Unexamined Patent Publication No. 2011-161491 Patent Document 3: Japanese Unexamined Patent Publication No. 2017-131945

However, while the method of patent document 3 can confirm motion abnormality during processing, it needs to acquire a two-dimensional intensity distribution, and there exists a problem that processing takes time.

Accordingly, an object of the present invention is to provide a laser processing apparatus capable of detecting an abnormality in a spatial light modulator at high speed.

According to one aspect of the present invention, in a laser processing apparatus, a laser oscillator for emitting a laser beam, a concentrator for condensing the laser beam emitted from the laser oscillator and irradiating it to a workpiece, the laser oscillator and the concentrator a laser beam irradiation unit including a spatial light modulator disposed therebetween, having a display unit displaying a phase pattern, and modulating the laser beam incident on the display unit according to the phase pattern and outputting the laser beam; and output from the spatial light modulator a light detection unit for detecting the intensity of the laser beam, and a control unit for controlling each component, wherein the control unit includes: a pattern control unit for controlling the phase pattern displayed on the display unit; a storage unit for storing, as a reference intensity, the intensity of the laser beam detected by the optical detection unit when the branching pattern, which is the phase pattern for diverging the laser beam, is displayed on the display unit; A laser processing apparatus having a determination unit for determining whether or not the spatial light modulator is operating normally based on whether or not the intensity of the laser beam has changed from the reference intensity.

In addition, in the laser processing apparatus according to one aspect of the present invention, the laser beam irradiation unit has a mirror for reflecting the laser beam emitted from the spatial light modulator toward the concentrator, and the light detection unit comprises: It may be configured to receive leakage light of the laser beam transmitted without being reflected by the mirror.

Further, in the laser processing apparatus according to one aspect of the present invention, a diffusion plate for diffusing the laser beam may be disposed between the mirror and the light detection unit.

Furthermore, in the laser processing apparatus according to one aspect of the present invention, between the spatial light modulator and the light detection unit, a focusing lens for concentrating the laser beam, and a focal point of the focusing lens or a vicinity of the focal position An aperture located at may be arranged.

Further, in the laser processing device according to one aspect of the present invention, the photodetection unit may be a photodiode.

According to one aspect of the present invention, an abnormality of the spatial light modulator can be detected at high speed.

1 is a perspective view showing a configuration example of a laser processing apparatus 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. 1 .
FIG. 3 is a schematic diagram showing a schematic configuration of the laser beam irradiation unit shown in FIG. 1 .
FIG. 4 is a schematic diagram showing an example of a phase pattern displayed on a display unit of the spatial light modulator shown in FIG. 3 .
FIG. 5 is a schematic diagram of a laser beam emitted from a display unit displaying the phase pattern shown in FIG. 4 .
FIG. 6 is a schematic diagram showing abnormal operation of the display unit of the spatial light modulator shown in FIG. 3 .
FIG. 7 is a schematic diagram of a laser beam emitted from the display unit shown in FIG. 6 .
FIG. 8 is a schematic diagram showing how the photodetection 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.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring an accompanying drawing. This invention is not limited by the content described in the following embodiment. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. In addition, the structure described below can be combined suitably. In addition, various omissions, substitutions, or changes may be made in the configuration without departing from the gist of the present invention.

(Embodiment)

First, the configuration of the laser processing apparatus 1 according to the embodiment of the present invention will be described based on the drawings. 1 is a perspective view showing a configuration example of a laser processing apparatus 1 according to an embodiment. FIG. 2 is a perspective view showing an example of a workpiece 100 to be processed by the laser processing apparatus 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 in the horizontal plane. The Y-axis direction is a direction orthogonal to the X-axis direction in a horizontal plane. The Z-axis direction is a direction orthogonal to the X-axis direction and the Y-axis direction. In the laser processing apparatus 1 of the embodiment, the machining feed direction is the X-axis direction, the indexing feed direction is the Y-axis direction, and the light converging point position adjustment direction is the Z-axis direction.

The laser processing apparatus 1 includes a holding table 10, a laser beam irradiation unit 20, an optical 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. A laser processing apparatus 1 according to an embodiment is a device that processes a to-be-processed object 100 by irradiating a laser beam 21 to the to-be-processed object 100 as a processing target. The processing of the workpiece 100 by the laser processing apparatus 1 is, for example, a modified layer formation process of forming a modified layer 106 (see FIG. 3) inside the workpiece 100 by stealth dicing; Groove processing for forming grooves in the surface 102 of the workpiece 100, cutting processing for cutting the workpiece 100 along the line 103 to be divided, and the like. In the embodiment, a configuration of forming the modified layer 106 in the workpiece 100 will be described.

The workpiece 100 may include, for example, silicon (Si), sapphire (Al ₂ O ₃ ), gallium arsenide (GaAs), silicon carbide (SiC), or lithium tantalate (LiTa ₃ ) on the substrate 101 (Fig. 2), such as disk-shaped semiconductor device wafers and optical device wafers. In addition, although the to-be-processed object 100 is disk-shaped in embodiment, it may not be disk-shaped in this invention. In the workpiece 100, for example, an annular frame 110 is attached, and a tape 111 having a larger diameter than the outer diameter of the workpiece 100 is adhered to the back surface 105 of the workpiece 100 to form a frame. It is conveyed and processed in a state supported in the opening of (110).

As shown in FIG. 2 , the workpiece 100 is formed on the surface 102 of the substrate 101 in a lattice-shaped line 103 to be divided and a region partitioned by the line 103 to be divided. It has a device (104). The device 104 is, for example, an image sensor such as an integrated circuit such as IC (Integrated Circuit) or LSI (Large Scale Integration), CCD (Charge Coupled Device), or CMOS (Complementary Metal Oxide Semiconductor).

In the embodiment, in the workpiece 100, a modified layer 106 (see FIG. 3) is formed along the division line 103. The workpiece 100 is divided into individual devices 104 along the modified layer 106 formed on the division line 103, and is divided into chips. Further, the chip has a square shape in the embodiment, but may be a rectangular shape in the present invention.

The holding table 10 shown in FIG. 1 and the like holds the workpiece 100 on the holding surface 11 . The holding surface 11 has a disc shape formed of porous ceramic or the like. The holding surface 11 is a plane parallel to the horizontal direction in the embodiment. The holding surface 11 is connected to a vacuum suction source through, for example, a vacuum suction path. The holding table 10 sucks and holds the workpiece 10 placed on the holding surface 11 . Around the holding table 10, a plurality of clamp portions 12 that clamp the annular frame 110 supporting the workpiece 100 are disposed.

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

The laser beam irradiation unit 20 is a unit that irradiates the laser beam 21 to the workpiece 100 held on the holding surface 11 of the holding table 10 . Of the laser beam irradiation unit 20, at least a concentrator 23 (see FIG. 3) is installed on a post 3 erected from the device main body 2 of the laser processing apparatus 1 and adjusts the position of the light condensing point described later. It is supported by unit 63. As shown in FIG. 3, the laser beam irradiation unit 20 includes a laser oscillator 22, a concentrator 23, a spatial light modulator 24, a polarizer 25, a focusing lens 26, and , an aperture 27, a relay lens 28, and a mirror 29. In addition, the laser beam irradiation unit 20 includes a condensing lens 32, a diffusion plate 33, and a filter 34 between the light detection unit 30 and the mirror 29.

The laser 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 transmissive or absorptive to the workpiece 100, and in the embodiment in which the modified layer forming process is performed, a wavelength that is transmissive. it's a laser beam

The concentrator 23 condenses the laser beam 21 emitted from the laser oscillator 22 onto the workpiece 100 held on the holding surface 11 of the holding table 10, and It is a condensing lens that emits light. The concentrator 23 condenses the laser beam 21 modulated by the spatial light modulator 24 onto the workpiece 100 . The convergence point 211 of the laser beam 21 condensed by the concentrator 23 is located inside the workpiece 100 in the modified layer forming process of the embodiment. In addition, 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 surface 102 side, but in the present invention, the surface ( 102) side may be held on the holding table 10, and the laser beam 21 may be irradiated from the rear surface 105 side.

The spatial light modulator 24 is installed between the laser oscillator 22 and the concentrator 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 laser oscillator 22 . The spatial light modulator 24 reflects and outputs the laser beam 21 in the embodiment, but may transmit and output the laser beam 21 in the present invention.

The spatial light modulator 24 has a display portion 241 . As shown in FIG. 4 , the display unit 241 displays a predetermined phase pattern 242 . The phase pattern 242 is displayed on the area 212 of the display unit 241 that 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 outputs the modulated laser beam 21 .

In the example shown in FIG. 4 , the phase pattern 242 is a branching pattern for branching and emitting the incident laser beam 21 . As shown in FIG. 4, in a state where the phase pattern 242, which is a branched pattern, is displayed on the display unit 241, the laser beam 21, as shown in FIG. 5, a plurality of sets of laser beams 21 branched into

As shown in FIG. 3 , a polarizing plate 25 is installed between the laser oscillator 22 and the spatial light modulator 24 . The polarizing plate 25 polarizes the laser beam 21 oscillated from the laser oscillator 22 into light in a specific direction.

The focusing lens 26 is disposed between the spatial light modulator 24 and the concentrator 23 . The focusing lens 26 focuses the laser beam 21 . In the embodiment, the laser beam 21 transmitted through the condensing lens 26 is focused and irradiated toward the aperture 27, and partially passes through the aperture while being partially blocked.

The aperture 27 is disposed between the spatial light modulator 24 and the concentrator 23 . The aperture 27 is located at or near the focal position of the focusing lens 26 . A laser beam 21 that has passed through the focusing lens 26 and is focused is incident on the aperture 27, and a part passes through the opening 27-1. The aperture 27 passes or partially blocks the laser beam 21 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 a branching pattern shown in FIG. 4, is split into a plurality of sets, and two sets of laser beams 21 It passes through the opening 27-1 of the aperture 27. The aperture 27 blocks high-shielding light generated by, for example, a branching pattern. Therefore, when the branching pattern is displayed as the phase pattern 242 on the display unit 241, higher order light is blocked by the aperture 27, so that the processing point (light convergence point) is higher than the case where the branching pattern is not displayed. The output of the laser beam 21 in (211)) is lowered. Note that the opening 27-1 of the aperture 27 is not limited to the circular shape shown in Fig. 5, but may be rectangular.

The relay lens 28 is disposed between the spatial light modulator 24 and the concentrator 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, through the mirror 29.

The mirror 29 reflects the laser beam 21 emitted from the spatial light modulator 24 toward the concentrator 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 transmitted through the relay lens 28 toward the concentrator 23 . Further, the mirror 29 transmits a part of the laser beam 21 transmitted through the relay lens 28 as leaked light 213 .

The light detection unit 30 detects the received light. The light detection unit 30 detects the intensity of the laser beam 21 emitted from the spatial light modulator 24, for example. 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 photodetection unit 30 transmits the laser beam 21 to the workpiece 100 by receiving the leak light 213 of the laser beam 21 transmitted without being reflected by the mirror 29. While irradiating, the output of the modulated laser beam 21 irradiated to the phase pattern 242 is detected.

The light detection unit 30 is, for example, a photodiode. The photodiode outputs to the control unit 90 a voltage value that changes according to the received amount of the laser beam 21 that has been received. The photodetection unit 30 is not limited to a photodiode, and may be, for example, an imaging unit provided with an imaging element such as a CCD imaging element or a CMOS imaging element, or may be a power meter.

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

The condensing lens 32 is installed between the mirror 29 and the light detection unit 30 . The condensing lens 32 condenses the leaked light 213 of the laser beam 21 transmitted through the mirror 29 right in front of the optical detection unit 30 .

The diffusion plate 33 is disposed between the mirror 29 and the condensing lens 32 . The diffuser plate 33 diffuses the leaked light 213 of the incident laser beam 21 to eliminate unevenness in intensity of the leaked light 213 of the transmitted laser beam 21 .

The filter 34 is disposed between the diffusion plate 33 and the condensing lens 32. The filter 34 is a filter that transmits a part of the leaked light 213 of the laser beam 21 . The filter 34 transmits, for example, only the laser beam 21 of the wavelength that the photodetection unit 30 receives among the leaked light 213 of the laser beam 21 . The filter 34 includes, for example, a Neutral Density (ND) filter. An ND filter is a filter that transmits light by dropping a certain amount without selecting a wavelength in a predetermined wavelength range.

The moving unit 60 shown in FIG. 1 relatively moves the converging point 211 (see FIG. 3 ) of the laser beam 21 along a plurality of planned division lines 103 set in the workpiece 100. It is a unit. The moving unit 60 includes a processing transport unit 61, an indexing transport unit 62, and a light condensing point position adjusting unit 63.

The processing transport unit 61 is a unit that relatively moves the holding table 10 and the light converging point 211 (see FIG. 3 ) of the laser beam irradiation unit 20 in the X-axis direction, which is the processing transport direction. The processing feed unit 61 moves the holding table 10 in the X-axis direction in the embodiment. The processing transport unit 61 is installed on the device main body 2 of the laser processing device 1 in the embodiment. The processing feed unit 61 supports the X-axis direction moving plate 14 so as to be movable in the X-axis direction.

The indexing transport unit 62 is a unit that relatively moves the holding table 10 and the light converging point 211 (see Fig. 3) of the laser beam irradiation unit 20 in the Y-axis direction, which is the indexing transport direction. The indexing transfer unit 62 moves the holding table 10 in the Y-axis direction in the embodiment. The indexing transport unit 62 is installed on the device main body 2 of the laser processing device 1 in the embodiment. The indexing transfer unit 62 supports the Y-axis direction moving plate 15 so as to be movable in the Y-axis direction.

The light converging point position adjusting unit 63 relatively moves the holding table 10 and the light converging point 211 (see Fig. 3) of the laser beam irradiation unit 20 in the Z-axis direction, which is the light converging point position adjusting direction. It is a unit. The light concentrating point position adjustment unit 63 moves at least the concentrator 23 of the laser beam irradiation unit 20 in the Z-axis direction in the embodiment. In the embodiment, the light converging point position adjusting unit 63 is installed on a pillar 3 erected from the device main body 2 of the laser processing device 1 . The light focusing point position adjusting unit 63 supports at least the light collector 23 of the laser beam irradiation unit 20 so as to be movable in the Z-axis direction.

The processing transfer unit 61, the indexing transfer unit 62, and the light concentrating point position adjustment unit 63 each include a known ball screw, a known pulse motor, and a known guide rail in the embodiment. . The ball screw is rotatably installed around the shaft center. The pulse motor rotates the ball screw around the shaft center. The guide rail of the processing feed unit 61 supports the X-axis direction moving plate 14 so that it can move in the X-axis direction. The guide rail of the processing feed unit 61 is fixedly installed to the Y-axis direction moving plate 15 . The guide rail of the indexing transport unit 62 supports the Y-axis direction moving plate 15 movably in the Y-axis direction. The guide rail of the indexing transfer unit 62 is fixedly installed to the device main body 2 . The guide rail of the light converging point position adjusting unit 63 supports at least the concentrator 23 of the laser beam irradiation unit 20 so as to be movable in the Z-axis direction. The guide rail of the light converging point position adjusting unit 63 is fixed to the pillar 3 and installed.

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 so as to be adjacent to the concentrator 23 (see Fig. 2) of the laser beam irradiation unit 20, for example. The imaging unit 70 captures an image of the workpiece 100 to obtain an image for performing alignment to align the workpiece 100 and the laser beam irradiation unit 20, and outputs the obtained image.

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

The control unit 90 controls each of the above-described components of the laser processing device 1, respectively, and causes the laser processing device 1 to perform a processing operation or the like for the workpiece 100. The control unit 90 is a computer including an arithmetic processing device as an arithmetic means, a storage device as a storage means, and an input/output interface device as a communication means. The arithmetic processing unit includes, for example, a microprocessor such as a CPU (Central Processing Unit). The storage device has a memory such as a hard disk drive (HDD), read only memory (ROM) or random access memory (RAM). An arithmetic processing unit performs various calculations based on a predetermined program stored in a storage device. The arithmetic processing device controls the laser processing device 1 by outputting various control signals to the above-mentioned respective components through the input/output interface device according to the arithmetic result. The control unit 90 includes a pattern control unit 91 , a storage unit 92 , and a determination unit 93 .

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

The storage unit 92 is included in the storage device of the control unit 90 . The storage unit 92 stores the intensity of the laser beam 21 detected by the photodetection unit 30 as a reference intensity when the divergent pattern is displayed on the display unit 241 by the pattern control unit 91 . That is, the storage unit 92 acquires and stores the intensity of the laser beam 21 that has been branched (modulated) by irradiating the branch pattern from the light detection unit 30 .

Based on the intensity of the laser beam 21 detected by the light detection unit 30, the determination unit 93 determines whether the spatial light modulator 24 is operating normally. More specifically, the determination unit 93 determines whether or not the intensity of the laser beam 21 detected by the photodetection unit 30 has changed from the reference intensity stored in the storage unit 92, and determines this determination. Based on the result, it is determined whether or not the spatial light modulator 24 is operating normally.

Next, a method for determining an operational abnormality of the spatial light modulator 24 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 , the display unit 241 at the time of operation abnormality cannot display the branching pattern as the phase pattern 242-1, and the region 212 to which the laser beam 21 is irradiated (see FIG. 3) ) does not display anything. In addition, in FIG. 6 of this specification, for description, the area to which the laser beam 21 is irradiated is depicted in gray for the black display unit 241, but the area to which the laser beam 21 is actually irradiated is also included Thus, the entire surface of the display unit 241 becomes a black state in which nothing is displayed.

At this time, as shown in Fig. 7, the laser beam 21 is not diverged. A laser beam 21 emitted from the branching pattern (phase pattern 242 in FIG. 4 ) displayed on the display unit 241 at normal times is blocked by the aperture 27 of high order light, whereas the branching pattern is not displayed. In the laser beam 21 emitted from the display unit 241, the high-order light is not blocked by the aperture 27. Accordingly, the output of the laser beam 21 at the processing point (converging point 211) increases, and the intensity of the laser beam 21 detected by the light detection unit 30 increases.

Here, the storage unit 92 is a laser beam 21 emitted from a divergent pattern (phase pattern 242 in FIG. 4 ) displayed on the display unit 241 at normal times and high-order light blocked by the aperture 27. , the intensity detected by the light detection unit 30 is stored as the reference intensity. 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 the branching pattern is not displayed and the high order light is not shielded changes from the reference intensity. If it is determined that it is, it is determined 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 photodetection unit 30 shown in FIG. 3 receives the laser beam 21 . 9 is a schematic diagram showing how the light detection unit 30 receives the laser beam 21 in the laser beam irradiation unit 20-1 according to the comparative example. Note that drawing of the filter 34 is omitted in FIGS. 8 and 9 .

As shown in FIG. 8 , the leaked light 213 of the laser beam 21 is incident on the diffusion plate 33 while being diverged by a diverging pattern displayed on the display unit 241 . The diffuser plate 33 diffuses the incident laser beam 21 to emit it in a state in which the influence of divergence is evened out. The condensing lens 32 condenses the leaked light 213 of the laser beam 21 in which the influence of divergence is evened out toward the optical detection unit 30 .

In contrast, as shown in FIG. 9 of the comparative example, in the laser beam irradiation unit 20-1 not provided with the diffusion plate 33, the leakage light 213 of the laser beam 21 is reflected in the display unit 241. It is incident on the condensing lens 32 in a state of divergence by the branching pattern shown in . The condensing lens 32 condenses the diverged laser beam 21 toward the optical detection unit 30 . However, there is a possibility that the output of the laser beam 21 detected by the light detection unit 30 becomes unstable when the diverged laser beam 21 is incident on a plurality of places on the light receiving surface of the light detection unit 30. there is.

For example, when the photodetection unit 30 is a photodiode, since the photodiode has a small light-receiving surface, there is a possibility that it cannot receive light of the diverged laser beam 21. In the laser beam irradiation unit 20 provided with the diffusion plate 33 of the embodiment, the optical detection unit 30 can stably measure the intensity of the laser beam 21 .

As described above, in the laser processing apparatus 1 according to the embodiment, when the laser beam irradiation unit 20 irradiates the laser beam 21 to the workpiece 100, the spatial light modulator 24 The laser beam 21 incident on the phase pattern 242 displayed on the display unit 241 is modulated corresponding to the phase pattern 242 . Specifically, the spatial light modulator 24 displays a branching pattern, which is a phase pattern 242 for branching the laser beam 21, on the display unit 241, and splits and emits the laser beam 21. In addition, the laser processing apparatus 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 storage unit 92 of the control unit 90 First, the intensity of the laser beam 21 branched by the branching pattern is stored in advance.

Here, when an abnormality occurs in the spatial light modulator 24 and no divergent pattern is displayed on the display unit 241, for example, when no phase pattern 242 is displayed, the laser beam reaching the processing point ( 21) changes. In the laser processing apparatus 1 of the embodiment, while irradiating the workpiece 100 with the laser beam 21, the output of the laser beam 21 emitted from the display unit 241 is detected, and the standard intensity and By comparing, an abnormality of the spatial light modulator 24 can be detected.

This makes it possible to detect an abnormality in the spatial light modulator 24 at high speed while processing one workpiece 100, so that anomaly can be recognized even during processing, and the entire workpiece 100 can be detected. It has the effect of reducing the possibility of being processed into defective chips.

In addition, this invention is not limited to the said embodiment. That is, various modifications can be made without departing from the gist of the present invention. For example, the laser beam irradiation unit 20 of the embodiment condenses the leaked light 213 of the laser beam 21, the influence of which is diverged by the diffusion plate 33, by the condensing lens 32, and detects the light. Although light is received by the unit 30, light may be received in an inverted image as a reduction relay system. In addition, by tilting the measurement optical system including the diffusion plate 33, the filter 34, and the light detection unit 30, the reflected light of the filter 34 is returned to the imaging means 31 or the laser oscillator 22. You might as well suppress it. As a result, the reflected light of the filter 34 is returned to the imaging means 31, thereby suppressing the influence on the reflectance measurement of the workpiece 100, and the reflected light of the filter 34 is transmitted to the laser oscillator 22. By returning, the occurrence of an influence on the oscillation of the laser beam 21 may be suppressed.

1 laser processing unit
10 maintenance table
11 Maintenance
20, 20-1 laser beam irradiation unit
21 laser beam
211 condensing point
212 area
213 leak light
22 laser oscillator
23 concentrator
24 spatial light modulator
241 display
242, 242-1 phase pattern
25 polarizer
26 focusing lens
27 Aperture
28 relay lens
29 mirror
30 light detection units
31 Imaging means
32 condensing lens
33 diffuser
34 filter
60 mobile units
61 machining feed unit
62 indexing transfer unit
90 control unit
91 pattern control
92 memory
93 Tribunal
100 work piece
103 line to be divided
102 surface
If 105
106 reformed layer

Claims (5)

In the laser processing device,
A laser oscillator for emitting a laser beam;
a concentrator for condensing the laser beam emitted from the laser oscillator and irradiating it to a workpiece;
A spatial light modulator disposed between the laser oscillator and the concentrator, having a display unit displaying a phase pattern, modulating the laser beam incident on the display unit according to the phase pattern, and outputting the modulated light
A laser beam irradiation unit comprising a;
an optical detection unit for detecting an intensity of the laser beam emitted from the spatial light modulator;
Control unit that controls each component
including,
The control unit,
a pattern controller for controlling the phase pattern displayed on the display unit;
a storage unit for storing, as a reference intensity, the intensity of the laser beam detected by the photodetection unit when a branching pattern, which is the phase pattern for diverging the laser beam, is displayed on the display unit by the pattern control unit;
A judging unit for judging whether or not the spatial light modulator is operating normally, based on whether or not the intensity of the laser beam detected by the optical detection unit has changed from the reference intensity.
With, laser processing device. According to claim 1,
The laser beam irradiation unit,
a mirror for reflecting the laser beam emitted from the spatial light modulator toward the concentrator;
The light detection unit,
The laser processing apparatus configured to receive leakage light of the laser beam transmitted without being reflected by the mirror. According to claim 2,
Between the mirror and the optical detection unit,
A laser processing apparatus in which a diffusion plate for diffusing the laser beam is disposed. According to any one of claims 1 to 3,
Between the spatial light modulator and the optical detection unit,
a focusing lens for focusing the laser beam;
The laser processing apparatus, wherein an aperture located at or near the focal position of the focusing lens is disposed. According to any one of claims 1 to 3,
The optical detection unit is a photodiode, the laser processing device.

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