CN115837512A - Laser processing apparatus - Google Patents
Laser processing apparatus Download PDFInfo
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- CN115837512A CN115837512A CN202211100019.4A CN202211100019A CN115837512A CN 115837512 A CN115837512 A CN 115837512A CN 202211100019 A CN202211100019 A CN 202211100019A CN 115837512 A CN115837512 A CN 115837512A
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Abstract
The invention provides a laser processing device which can detect the abnormity of a spatial light modulator at high speed. The laser processing apparatus includes: a laser beam irradiation unit including a spatial light modulator disposed between the laser oscillator and the condenser, the spatial light modulator modulating an incident laser beam according to a phase pattern displayed on the display unit and emitting the modulated laser beam; a light detection unit that detects the intensity of the laser beam; a pattern control unit for controlling the phase pattern displayed on the display unit; a storage section that stores, as a reference intensity, an intensity of the laser beam detected by the light detection unit when a branching pattern that is a phase pattern for branching the laser beam is displayed on the display section; and a determination unit that determines whether or not the spatial light modulator is operating normally, based on whether or not the intensity of the laser beam detected by the light detection unit has changed from a reference intensity.
Description
Technical Field
The present invention relates to a laser processing apparatus.
Background
For manufacturing a semiconductor device, the following processing methods are known: a modified layer is formed by positioning a laser beam converging point inside a wafer and irradiating the wafer along streets (planned dividing lines), and the wafer is divided by applying an external force (see patent document 1). In a laser processing apparatus for realizing the above processing method, a laser beam emitted from a laser oscillator is modulated by a spatial light modulator, condensed by a condenser lens, and irradiated onto a wafer.
In recent years, in order to shorten the processing time, a method of branching a laser beam by a spatial light modulator and processing at a plurality of converging points is used (see patent document 2). In this laser processing apparatus, when the spatial light modulator does not normally operate due to a defect or abnormality, the laser beam may not be appropriately branched and may be irradiated in an undivided state, thereby causing a processing defect.
Therefore, various methods have been proposed for detecting a malfunction of the spatial light modulator. For example, patent document 3 discloses the following method: the operation is confirmed by displaying a phase pattern including a mark that modulates a part of a pupil plane that is not incident on the condenser lens on the spatial light modulator, and acquiring an intensity distribution of the phase pattern including the mark.
Patent document 1: japanese patent laid-open publication No. 2011-051011
Patent document 2: japanese patent laid-open publication No. 2011-161491
Patent document 3: japanese patent laid-open publication No. 2017-131945
However, the method of patent document 3 can check an operation abnormality during machining, but it is necessary to obtain a two-dimensional intensity distribution, and there is a problem that it takes time to perform the processing.
Disclosure of Invention
Accordingly, an object of the present invention is to provide a laser processing apparatus capable of detecting an abnormality of a spatial light modulator at high speed.
According to one aspect of the present invention, there is provided a laser processing apparatus, comprising: a laser beam irradiation unit including a laser oscillator that emits a laser beam, a condenser that condenses the laser beam emitted from the laser oscillator to irradiate a workpiece with the laser beam, and a spatial light modulator that is disposed between the laser oscillator and the condenser, has a display portion that displays a phase pattern, and modulates and emits the laser beam incident on the display portion in accordance with the phase pattern; a light detection unit that detects an intensity of the laser beam emitted from the spatial light modulator; and a control unit that controls each component, the control unit including: a pattern control unit for controlling the phase pattern displayed on the display unit; a storage section that stores, as a reference intensity, an intensity of the laser beam detected by the light detection unit when a branching pattern that is the phase pattern for branching the laser beam is displayed on the display section by the pattern control section; and a determination unit that determines whether or not the spatial light modulator operates normally, based on whether or not the intensity of the laser beam detected by the light detection unit has changed from the reference intensity.
In the laser processing apparatus according to one aspect of the present invention, the laser beam irradiation unit may include a mirror that reflects the laser beam emitted from the spatial light modulator toward the condenser, and the light detection unit may be configured to receive leak light of the laser beam that is transmitted without being reflected by the mirror.
In the laser processing apparatus according to the aspect of the present invention, a diffusion plate for diffusing the laser beam may be disposed between the mirror and the light detection unit.
In the laser processing apparatus according to the aspect of the present invention, the spatial light modulator may be disposed between the spatial light modulator and the light detection unit: a focusing lens that converges the laser beam; and a diaphragm positioned at or near a focal position of the focusing lens.
In the laser processing apparatus according to one aspect of the present invention, the light detection unit may be a photodiode.
According to one embodiment of the present invention, an abnormality of the spatial light modulator can be detected at high speed.
Drawings
Fig. 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 in the laser processing apparatus shown in fig. 1.
Fig. 3 is a schematic view showing a schematic structure 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 the display portion of the spatial light modulator shown in fig. 3.
Fig. 5 is a schematic view of a laser beam emitted from a display portion displaying the phase pattern shown in fig. 4.
Fig. 6 is a schematic diagram showing a case where the operation of the display unit of the spatial light modulator shown in fig. 3 is abnormal.
Fig. 7 is a schematic view of a laser beam emitted from the display portion shown in fig. 6.
Fig. 8 is a schematic diagram showing a case where the light detection unit shown in fig. 3 receives a laser beam.
Fig. 9 is a schematic diagram showing a case where a laser beam is received by a light detection unit in a laser beam irradiation unit of a comparative example.
Description of the reference symbols
1: a laser processing device; 10: a holding table; 11: a holding surface; 20. 20-1: a laser beam irradiation unit; 21: a laser beam; 211: a light-gathering point; 212: an area; 213: light leakage; 22: a laser oscillator; 23: a condenser; 24: a spatial light modulator; 241: a display unit; 242. 242-1: a phase pattern; 25: a polarizing plate; 26: a focusing lens; 27: a diaphragm; 28: a relay lens; 29: a mirror; 30: a light detection unit; 31: a shooting unit; 32: a condenser lens; 33: a diffusion plate; 34: a filter; 60: a mobile unit; 61: a processing feeding unit; 62: an indexing feed unit; 90: a control unit; 91: a pattern control section; 92: a storage unit; 93: a determination unit; 100: a workpiece; 103: dividing the predetermined line; 102: a front side; 105: a back side; 106: and modifying the layer.
Detailed Description
Hereinafter, embodiments of 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 embodiments. The components described below include those that can be easily conceived by those skilled in the art, and substantially the same ones. The following structures may be combined as appropriate. Various omissions, substitutions, and changes in the structure may be made without departing from the spirit of the present invention.
[ embodiment ]
First, the structure of the laser processing apparatus 1 according to the embodiment of the present invention will be described with reference to the drawings. Fig. 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 the object 100 to be processed in the laser processing apparatus 1 shown in fig. 1. Fig. 3 is a schematic view showing a schematic structure of the laser beam irradiation unit 20 shown in fig. 1. Fig. 4 is a schematic diagram showing an example of the phase pattern 242 displayed on the display portion 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 section 241 showing the phase pattern 242 shown in fig. 4.
In the following description, the X-axis direction is one direction in 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 direction and the Y-axis direction. 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 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, a light detection unit 30 (see fig. 3), an imaging unit 31, a moving unit 60, an imaging unit 70, an input unit 80, and a control unit 90. The laser processing apparatus 1 of the embodiment is an apparatus for processing a workpiece 100 by irradiating the workpiece 100 as a processing target with a laser beam 21. The processing of the workpiece 100 by the laser processing apparatus 1 is, for example, modified layer forming processing for forming a modified layer 106 (see fig. 3) inside the workpiece 100 by stealth dicing, groove processing for forming a groove in the front surface 102 of the workpiece 100, cutting processing for cutting the workpiece 100 along the line to divide 103, or the like. In the embodiment, a structure in which the modified layer 106 is formed in the workpiece 100 will be described.
The workpiece 100 is made of, for example, silicon (Si) or sapphire (Al) 2 O 3 ) Gallium arsenide (GaAs), silicon carbide (SiC) or lithium tantalate (LiTa) 3 ) And a wafer such as a disc-shaped semiconductor device wafer or an optical device wafer serving as the substrate 101 (see fig. 2). In the embodiment, the workpiece 100 has a disc shape, but may not have a disc shape in the present invention. The object 100 is conveyed and processed in a state where, for example, a belt 111 having a ring-shaped frame 110 attached thereto and having a diameter larger than the outer diameter of the object 100 is attached to the rear surface 105 of the object 100 and supported in the opening of the frame 110.
As shown in fig. 2, the workpiece 100 includes: planned dividing lines 103 set in a grid pattern on the front surface 102 of the substrate 101; and devices 104 formed in regions partitioned by the dividing lines 103. The Device 104 is, for example, an Integrated Circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), or an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).
In the embodiment, the object 100 is formed with the modified layer 106 along the planned dividing lines 103 (see fig. 3). The object 100 is divided into individual devices 104 along the modified layers 106 formed in the lines to divide 103, and is singulated into chips. In the embodiment, the chip has a square shape, but may have a rectangular shape in the present invention.
A holding table 10 shown in fig. 1 and the like holds a workpiece 100 by a holding surface 11. The holding surface 11 is a disk shape formed 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 via a vacuum suction path, for example. The holding table 10 sucks and holds the workpiece 100 placed on the holding surface 11. A plurality of clamping portions 12 for clamping an annular frame 110 for supporting the workpiece 100 are arranged around the holding table 10.
The holding table 10 is rotated by the rotating unit 13 about an axis parallel to the Z-axis direction. The rotating unit 13 is supported by the X-axis moving plate 14. The rotating unit 13 and the holding table 10 are moved in the X-axis direction by a later-described processing feed unit 61 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 index feed unit 62 described later via the X-axis direction moving plate 14, the work feed unit 61, and the Y-axis direction moving plate 15.
The laser beam irradiation unit 20 is a unit that irradiates the workpiece 100 held by the holding surface 11 of the holding table 10 with the laser beam 21. At least the condenser 23 (see fig. 3) of the laser beam irradiation unit 20 is supported by a condensing point position adjusting unit 63 described later, and the condensing point position adjusting unit 63 is provided on a column 3 provided upright from the apparatus main body 2 of the laser processing apparatus 1. As shown in fig. 3, the laser beam irradiation unit 20 includes: a laser 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 includes a condenser lens 32, a diffuser 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 of performing the modified layer forming process, is a laser beam having a wavelength that is transmissive.
The condenser 23 is a condenser lens for condensing the laser beam 21 emitted from the laser oscillator 22 on the workpiece 100 held on the holding surface 11 of the holding table 10 and irradiating the workpiece 100 with the laser beam. The condenser 23 condenses the laser beam 21 modulated by the spatial light modulator 24 on the workpiece 100. The converging point 211 of the laser beam 21 converged 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 by 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 by 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 laser oscillator 22 and the condenser 23. The spatial light modulator 24 modulates the incident laser beam 21 by electrically controlling spatial distribution such as amplitude, phase, polarization, and the like of the laser beam 21 emitted from the laser oscillator 22. In the embodiment, the spatial light modulator 24 reflects the laser beam 21 and outputs it, but in the present invention, the laser beam 21 may be transmitted and output.
The spatial light modulator 24 includes a display portion 241. As shown in fig. 4, the display portion 241 displays a predetermined phase pattern 242. The phase pattern 242 is displayed in the display portion 241 in the region 212 irradiated with the laser beam 21. The spatial light modulator 24 modulates the laser beam 21 incident on the display portion 241 according to the phase pattern 242 and emits the modulated laser beam.
In the example shown in fig. 4, the phase pattern 242 is a branching pattern for branching the incident laser beam 21 and emitting it. In a state where the phase pattern 242 as a branching pattern is displayed on the display portion 241 as shown in fig. 4, the laser beam 21 is branched into a plurality of laser beams 21 as shown in fig. 5.
As shown in fig. 3, a polarizing plate 25 is disposed 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 condenser 23. The focusing lens 26 converges the laser beam 21. In the embodiment, the laser beam 21 transmitted through the focusing lens 26 is converged toward the diaphragm 27 to be irradiated, a part of which is shielded, and a part of which passes through the opening.
The aperture 27 is disposed between the spatial light modulator 24 and the condenser 23. The diaphragm 27 is positioned at or near the focal position of the focusing lens 26. The laser beam 21 condensed by the focusing lens 26 is incident on the diaphragm 27, and a part passes through the opening 27-1. The aperture 27 passes or shields a part of the laser beam 21 modulated in accordance with the phase pattern 242 in the spatial light modulator 24.
As shown in fig. 5, the laser beam 21 emitted from the display section 241 displaying the phase pattern 242 shown in fig. 4 as a branching pattern is branched into a plurality of pieces, two of the laser beams 21 passing through the opening 27-1 of the diaphragm 27. The diaphragm 27, for example, shields the high-order light generated by the branching pattern. Therefore, in the case where the branch pattern is displayed as the phase pattern 242 on the display portion 241, the high-order light is shielded by the stop 27, and therefore, the output of the laser beam 21 at the processing point (the converging point 211) is reduced as compared with the case where the branch pattern is not displayed. The aperture 27-1 of the diaphragm 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 converged by the focusing lens 26 and passed through the stop 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 transmitted through the relay lens 28 toward the condenser 23. Further, the mirror 29 transmits a part of the laser beam 21 transmitted through the relay lens 28 as leak light 213.
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 that is modulated according to the phase pattern 242, emitted from the display portion 241, and passed through the aperture 27. In the embodiment, the light detection unit 30 receives the leak light 213 of the laser beam 21 that has been transmitted without being reflected by the mirror 29, and detects the output of the laser beam 21 modulated by being irradiated to the phase pattern 242 while irradiating the laser beam 21 to the workpiece 100.
The light detection unit 30 is, for example, a photodiode. The photodiode outputs a voltage value that varies according to the received light amount 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 an imaging unit having an imaging element such as a CCD imaging element or a CMOS imaging element, or may be a power meter.
The imaging unit 31 images a processing point (focal point 211) of the laser beam 21 irradiated to the workpiece 100 held by the holding table 10. The imaging unit 31 includes a CCD camera or the like, for example. The photographing unit 31 may be used in common with the photographing unit 70 described later.
The condenser lens 32 is disposed between the mirror 29 and the light detection unit 30. The condenser lens 32 condenses the leak light 213 of the laser beam 21 transmitted through the mirror 29 to the front side of the light detection unit 30.
The diffuser 33 is disposed between the reflector 29 and the condenser lens 32. The diffusion plate 33 diffuses the leak light 213 of the incident laser beam 21, thereby eliminating intensity unevenness of the leak 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 is a filter that transmits a part of leak light 213 of the laser beam 21. The filter 34 transmits, for example, only the laser beam 21 having the wavelength received by the light detection unit 30 out of the leak 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 light by reducing the amount of light by a certain amount without selecting a wavelength in a predetermined wavelength band.
The moving means 60 shown in fig. 1 is a means for relatively moving a converging point 211 (see fig. 3) of the laser beam 21 along a plurality of lines 103 set on the work 100. The mobile unit 60 includes: a machining feed unit 61, an index feed unit 62, and a focal point position adjustment unit 63.
The processing and feeding unit 61 is a unit that relatively moves the holding table 10 and a converging point 211 (see fig. 3) of the laser beam irradiation unit 20 in the X-axis direction, which is a processing and feeding direction. In the embodiment, the processing feed unit 61 moves the holding table 10 in the X-axis direction. In the embodiment, the processing and feeding unit 61 is provided in the apparatus main body 2 of the laser processing apparatus 1. The machining feed unit 61 supports the X-axis direction moving plate 14 to be movable in the X-axis direction.
The index feeding unit 62 is a unit that relatively moves the holding table 10 and a converging point 211 (see fig. 3) of the laser beam irradiation unit 20 in the Y-axis direction, which is the index feeding direction. In the embodiment, the index feeding unit 62 moves the holding table 10 in the Y-axis direction. In the embodiment, the index feeding unit 62 is provided on the apparatus main body 2 of the laser processing apparatus 1. The index feeding unit 62 supports the Y-axis direction moving plate 15 to be movable in the Y-axis direction.
The focal point position adjusting unit 63 is a unit that relatively moves the holding table 10 and a focal point 211 (see fig. 3) of the laser beam irradiation unit 20 in a Z-axis direction that is a focal point position adjusting direction. In the embodiment, the focal point position adjusting 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 adjusting means 63 is provided on the column 3 that is erected from the apparatus main body 2 of the laser processing apparatus 1. The focal point position adjusting means 63 supports at least the condenser 23 of the laser beam irradiation means 20 to be movable in the Z-axis direction.
In the embodiment, the machining feed unit 61, the indexing feed unit 62, and the focal point position adjusting unit 63 each include a known ball screw, a known pulse motor, and a known guide rail. The ball screw is provided to be rotatable about the axis. The pulse motor rotates the ball screw about the axis. The guide rail of the machining feed unit 61 supports the X-axis direction moving plate 14 to be movable in the X-axis direction. The guide rail of the machining feed unit 61 is fixedly provided to the Y-axis direction moving plate 15. The guide rail of the index feeding unit 62 supports the Y-axis direction moving plate 15 to be movable in the Y-axis direction. The guide rail of the index feeding unit 62 is fixedly provided to the apparatus main body 2. The guide rail of the condensed point position adjusting unit 63 supports at least the condenser 23 of the laser beam irradiation unit 20 to be movable in the Z-axis direction. The guide rail of the focal point position adjusting unit 63 is fixedly provided to the column 3.
The imaging unit 70 images the workpiece 100 held by the holding table 10. The photographing unit 70 includes a CCD camera or an infrared camera. The imaging unit 70 is fixed adjacent to the condenser 23 (see fig. 2) of the laser beam irradiation unit 20, for example. The imaging unit 70 images the workpiece 100 to obtain an image for performing alignment, that is, positioning of the workpiece 100 and the laser beam irradiation unit 20, and outputs the obtained image.
In the embodiment, the input unit 80 is a touch panel included in a display device such as a liquid crystal display device. The input unit 80 can accept various operations such as registration of processing content information by an operator. The input unit 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 apparatus 1 to cause the laser processing apparatus 1 to perform a processing operation on the workpiece 100. The control unit 90 is a computer, and the control unit 90 includes: an arithmetic processing device as arithmetic means; a storage device as a storage unit; and an input/output interface device as a communication unit. The arithmetic Processing Unit includes a microprocessor such as a Central Processing Unit (CPU). The storage device includes a Memory such as a Hard Disk Drive (HDD), a Read Only Memory (ROM), or a Random Access Memory (RAM). The arithmetic processing device performs various calculations based on a predetermined program stored in the storage device. The arithmetic processing unit outputs various control signals to the above-described components via the input/output interface device in accordance with the arithmetic result, and controls the laser processing apparatus 1. The control unit 90 includes a pattern control unit 91, a storage unit 92, and a determination unit 93.
The pattern control unit 91 controls the phase pattern 242 displayed on the display unit 241 of the spatial light modulator 24. The pattern control unit 91 displays the phase pattern 242 in the region 212 of the display unit 241, which is irradiated with the laser beam 21, 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 section 92 stores the intensity of the laser beam 21 detected by the light detection unit 30 when the branch pattern is displayed on the display section 241 by the pattern control section 91 as a reference intensity. That is, the storage section 92 acquires and stores the intensity of the laser beam 21 irradiated to the branching pattern and branched (modulated) from the light detection unit 30.
The determination unit 93 determines whether or not the spatial light modulator 24 normally operates, based on the intensity of the laser beam 21 detected by the light detection unit 30. More specifically, the determination unit 93 determines whether or not the intensity of the laser beam 21 detected by the light detection unit 30 has changed from the reference intensity stored in the storage unit 92, and determines whether or not the spatial light modulator 24 is operating normally based on the determination result.
Next, a method of determining an operational abnormality of the spatial light modulator 24 will be described. Fig. 6 is a schematic diagram showing a case where the operation of the display section 241 of the spatial light modulator 24 shown in fig. 3 is abnormal. Fig. 7 is a schematic view of the laser beam 21 emitted from the display portion 241 shown in fig. 6.
In the example shown in fig. 6, the display portion 241 in the event of an abnormal operation cannot display a branch pattern as the phase pattern 242-1, and nothing is displayed in the region 212 (see fig. 3) irradiated with the laser beam 21. In fig. 6 of the present specification, for the sake of explanation, the region irradiated with the laser beam 21 is depicted in gray for the black display portion 241, but actually, the black display portion 241 is in a state where nothing is displayed over the entire surface of the display portion 241 including the region irradiated with the laser beam 21.
At this time, as shown in fig. 7, the laser beam 21 is not branched. While the laser beam 21 emitted according to the branching pattern (phase pattern 242 in fig. 4) displayed on the display portion 241 at the normal time is shielded from the high-order light by the stop 27, the laser beam 21 emitted from the display portion 241 not displaying the branching pattern is not shielded from the high-order light by the stop 27. Therefore, the output of the laser beam 21 at the processing point (focal point 211) increases, and the intensity of the laser beam 21 detected by the light detection unit 30 increases.
Here, the storage unit 92 stores, as a reference intensity, an intensity detected by the light detection unit 30 of the laser beam 21 emitted from the branch pattern (the phase pattern 242 in fig. 4) displayed on the display unit 241 in the normal state and having the high-order light blocked by the aperture 27. When the determination unit 93 determines that the intensity of the laser beam 21 emitted from the display unit 241, which does not display the branching pattern and in which the high-order light is not shielded, detected by the light detection unit 30 has changed from the reference intensity, it is determined that the spatial light modulator 24 is not operating normally.
Next, the function of the diffuser plate 33 will be described. Fig. 8 is a schematic diagram showing a case where the light detection unit 30 shown in fig. 3 receives the laser beam 21. Fig. 9 is a schematic diagram showing a case where the laser beam 21 is received by the light detection unit 30 in the laser beam irradiation unit 20-1 of the comparative example. In fig. 8 and 9, the optical filter 34 is not depicted.
As shown in fig. 8, the leak light 213 of the laser beam 21 is incident on the diffusion plate 33 in a state of being branched according to the branching pattern displayed on the display portion 241. The diffusion plate 33 diffuses the incident laser beam 21, and emits the laser beam with the influence of the branching balanced. The condensing lens 32 condenses the leak light 213 of the laser beam 21, in which the influence of the branching is equalized, toward the light detection unit 30.
In contrast, as shown in fig. 9 of the comparative example, in the laser beam irradiation unit 20-1 without the diffusion plate 33, the leak light 213 of the laser beam 21 is incident on the condenser lens 32 in a state of being branched according to the branching pattern displayed on the display portion 241. The condensing lens 32 condenses the laser beam 21, which maintains the branched state, toward the light detection unit 30. However, the laser beam 21 in the branched state enters a plurality of portions on the light receiving surface of the light detection unit 30, and thus the output of the laser beam 21 detected by the light detection unit 30 may become unstable.
For example, when the light detection unit 30 is a photodiode, the laser beam 21 in the branched state may not be received because the light receiving surface of the photodiode is small. The laser beam irradiation unit 20 of the embodiment having the diffusion plate 33 can stably measure the intensity of the laser beam 21 by the light detection unit 30.
As described above, in the laser processing apparatus 1 according to the embodiment, when the laser beam 21 is irradiated to the workpiece 100, the laser beam irradiation unit 20 modulates the laser beam 21 incident on the phase pattern 242 displayed on the display portion 241 of the spatial light modulator 24 in accordance with the phase pattern 242. Specifically, the spatial light modulator 24 displays a branch pattern, which is a phase pattern 242 for branching the laser beam 21, on the display section 241, and branches and emits the laser beam 21. The laser processing apparatus 1 includes the 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 stores in advance the intensity of the laser beam 21 branched by the branching pattern.
Here, when an abnormality occurs in the spatial light modulator 24 and no branch pattern is displayed on the display portion 241, for example, when any phase pattern 242 is not displayed, the output of the laser beam 21 reaching the processing point changes. In the laser processing apparatus 1 of the embodiment, the abnormality of the spatial light modulator 24 can be detected by detecting the output of the laser beam 21 emitted from the display portion 241 while irradiating the workpiece 100 with the laser beam 21 and comparing the detected output with the reference intensity at the normal time.
Thus, since the abnormality of the spatial light modulator 24 can be detected at high speed while one workpiece 100 is being processed, the following effects are obtained: the abnormality can be noticed even during the processing, and the possibility that the entire workpiece 100 is processed to obtain a defective chip can be reduced.
The present invention is not limited to the above embodiments. That is, various modifications can be made and implemented without departing from the scope of the present invention. For example, although the laser beam irradiation unit 20 of the embodiment collects the leak light 213 of the laser beam 21 in which the influence of the branching is balanced by the diffusion plate 33 by the condenser lens 32 and receives the collected light by the light detection unit 30, the leak light 213 may be transferred and received as a reduction relay system. In addition, it is possible to suppress the reflected light of the optical filter 34 from returning to the photographing unit 31 or the laser oscillator 22 by tilting the measurement optical system including the diffusion plate 33, the optical filter 34, and the light detection unit 30. Thereby, it is possible to suppress the influence on the measurement of the reflectance of the workpiece 100 due to the return of the reflected light of the filter 34 to the imaging unit 31, and to suppress the influence on the oscillation of the laser beam 21 due to the return of the reflected light of the filter 34 to the laser oscillator 22.
Claims (5)
1. A laser processing apparatus, wherein,
the laser processing apparatus includes:
a laser beam irradiation unit including a laser oscillator that emits a laser beam, a condenser that condenses the laser beam emitted from the laser oscillator to irradiate a workpiece, and a spatial light modulator that is disposed between the laser oscillator and the condenser, has a display unit that displays a phase pattern, and modulates and emits the laser beam incident on the display unit in accordance with the phase pattern;
a light detection unit that detects an intensity of the laser beam emitted from the spatial light modulator; and
a control unit for controlling each component,
the control unit has:
a pattern control unit for controlling the phase pattern displayed on the display unit;
a storage section that stores, as a reference intensity, an intensity of the laser beam detected by the light detection unit when a branching pattern that is the phase pattern for branching the laser beam is displayed on the display section by the pattern control section; and
and a determination unit that determines whether or not the spatial light modulator is operating normally, based on whether or not the intensity of the laser beam detected by the light detection unit has changed from the reference intensity.
2. The laser processing apparatus according to claim 1,
the laser beam irradiation unit has a mirror that reflects the laser beam emitted from the spatial light modulator toward the condenser,
the light detection unit is configured to receive leakage light of the laser beam transmitted without being reflected by the mirror.
3. The laser processing apparatus according to claim 2,
a diffusion plate for diffusing the laser beam is disposed between the mirror and the light detection unit.
4. The laser processing apparatus according to any one of claims 1 to 3,
the spatial light modulator and the light detection unit are provided with:
a focusing lens that converges the laser beam; and
and a diaphragm positioned at or near a focal position of the focusing lens.
5. The laser processing apparatus according to any one of claims 1 to 3,
the light detection unit is a photodiode.
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| JP2021-153409 | 2021-09-21 | ||
| JP2021153409A JP2023045156A (en) | 2021-09-21 | 2021-09-21 | Laser processing device |
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| CN115837512A true CN115837512A (en) | 2023-03-24 |
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| KR (1) | KR20230042565A (en) |
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| TW (1) | TW202313235A (en) |
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| JP5775265B2 (en) | 2009-08-03 | 2015-09-09 | 浜松ホトニクス株式会社 | Laser processing method and semiconductor device manufacturing method |
| JP2011161491A (en) | 2010-02-10 | 2011-08-25 | Disco Abrasive Syst Ltd | Laser beam machining apparatus |
| JP6644563B2 (en) | 2016-01-28 | 2020-02-12 | 浜松ホトニクス株式会社 | Laser light irradiation device |
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2021
- 2021-09-21 JP JP2021153409A patent/JP2023045156A/en active Pending
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| TW202313235A (en) | 2023-04-01 |
| JP2023045156A (en) | 2023-04-03 |
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