Laser processing apparatus and laser processing method

Abstract

To inhibit processed waste produced when manufacturing a pin hole of a spatial filter with a laser processing device from adhering to an optical element in its periphery.SOLUTION: A laser processing device comprises a laser oscillator 22, a condenser 23, a lens 31 disposed therebetween, a filter material 33 disposed at a condensing point position 26 of the lens 31, and a box-shaped member 40 that can move forward and backward between a non-acting position outside an optical path and an acting position 42 where the filter material 33 is covered inside the optical path, with a window transmitting a laser beam 21 at the acting position 42. In the laser processing device, a spatial filter 30 including the lens 31 and the filter material 33 is manufactured by irradiating the filter material 33 with the laser beam 21 to form a pin hole in a state where the box-shaped member 40 is positioned at the acting position 42 and the inside thereof is sucked, and a workpiece 100 is processed by irradiating it with the laser beam 21 in a state where the box-shaped member 40 is positioned at the non-acting position.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a laser processing apparatus and a laser processing method. [Background Art]

[0002] There has been known a laser processing apparatus that performs processing by irradiating a laser beam along lines to divide set on a workpiece in order to divide and singulate a plate-shaped workpiece such as a semiconductor wafer. In a laser processing apparatus, a laser beam emitted from a laser oscillator is guided to a processing point by a plurality of optical elements arranged on an optical axis.

[0003] In a laser processing apparatus for performing processing with a high-quality laser beam, a spatial filter that removes optical noise contained in the laser beam is arranged on the optical axis between the laser oscillator and a condenser. The spatial filter is composed of a lens and a pinhole arranged at the focal point position of the lens, removes interference fringes generated due to particle adhesion, scratches on the lens, etc., and shapes a noise-free high-quality laser beam.

[0004] By the way, with spatial filters, it is difficult to accurately position the pinhole at the focal point position of the lens, and there is a problem that adjustment takes time. In response to this, for example, Patent Document 1 discloses a method of processing a pinhole and processing a workpiece using the same laser processing apparatus. According to this method, manufacturing of the spatial filter and positioning of the pinhole at the focal point position of the lens can be performed with high accuracy, so positioning adjustment becomes extremely easy. [Prior Art Literature] [Patent Literature]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 11-077358 [Summary of the Invention] [Problems that the invention aims to solve]

[0006] However, in the invention described in Patent Document 1, processing debris generated during pinhole processing could adhere to surrounding optical elements such as lenses, potentially resulting in a decrease in processing quality.

[0007] This invention has been made in view of the above problems, and its purpose is to provide a laser processing apparatus and a laser processing method that can suppress the adhesion of processing debris generated when manufacturing pinholes in a spatial filter to surrounding optical elements. [Means for solving the problem]

[0008] To solve the above-mentioned problems and achieve the objective, the present invention provides a laser processing apparatus that processes a workpiece by irradiating it with a laser beam, comprising: a holding table for holding the workpiece; a laser beam irradiation unit for irradiating a laser beam; a moving unit for relatively moving the focal point of the laser beam and the workpiece held on the holding table; and a control unit for controlling each component, wherein the laser beam irradiation unit comprises: a laser oscillator; a concentrator for focusing the laser beam emitted from the laser oscillator and irradiating the workpiece with it; a lens disposed between the laser oscillator and the concentrator; a filter material disposed at the focal point position of the lens; and a box-shaped member having a suction port communicating with a suction source. The box-shaped member is movable back and forth between a non-working position, which is outside the optical path of the laser beam, and an working position, which is within the optical path of the laser beam and covers the filter material, and further has a window that transmits the laser beam at the working position, the control unit causes the box-shaped member to be positioned at the working position and the inside of the box-shaped member to be sucked, and to irradiate the filter material with the laser beam through the window to form a pinhole in the filter material, thereby manufacturing a spatial filter including the lens and the filter material, and with the box-shaped member positioned at the non-working position, to irradiate a workpiece held on the holding table with the laser beam to process the workpiece.

[0009] Furthermore, the laser processing apparatus of the present invention is a laser processing apparatus that processes a workpiece by irradiating it with a laser beam, comprising: a holding table for holding the workpiece; a laser beam irradiation unit for irradiating a laser beam; a moving unit for relatively moving the focal point of the laser beam and the workpiece held on the holding table; and a control unit for controlling each component, wherein the laser beam irradiation unit comprises: a laser oscillator; a concentrator for focusing the laser beam emitted from the laser oscillator and irradiating the workpiece with it; a lens disposed between the laser oscillator and the concentrator; a filter material disposed at the focal point position of the lens; and a suction port communicating with a suction source, and disposed in a position to cover the filter material within the optical path of the laser beam. The control unit comprises a box-shaped member, the box-shaped member having an opening through which the laser beam passes, and a window that is movable back and forth between a non-operating position in which the opening is open and an operating position in which the opening is closed, and which transmits the laser beam at the operating position, and the control unit causes the window to be positioned at the operating position and the inside of the box-shaped member to be sucked, and to irradiate the filter material with the laser beam through the window to form a pinhole in the filter material, thereby manufacturing a spatial filter including the lens and the filter material, and with the window positioned at the non-operating position, to irradiate a workpiece held on the holding table with the laser beam to process the workpiece.

[0010] Furthermore, in the laser processing apparatus of the present invention, the filter material may be movable in a direction perpendicular to the optical axis direction of the laser beam.

[0011] Furthermore, the present invention relates to a laser processing method that processes a workpiece by focusing a laser beam emitted from a laser oscillator with a condenser and irradiating it with the workpiece, comprising: a spatial filter manufacturing step in which a lens is placed between the laser oscillator and the condenser, a filter material is placed at the focal point of the lens, and a laser beam is emitted from the laser oscillator to form a pinhole in the filter material, thereby manufacturing a spatial filter including the lens and the filter material; and a laser processing step in which the workpiece is processed by irradiating it with the laser beam through the pinhole in the spatial filter, wherein in the spatial filter manufacturing step, a box-shaped member having a window that transmits the laser beam is placed in a position to cover the filter material, and the laser beam is irradiated onto the filter material through the window while suction is applied to the inside of the box-shaped member.

[0012] Furthermore, in the laser processing method of the present invention, in the spatial filter manufacturing step, the filter material may be moved in a direction perpendicular to the optical axis direction of the laser beam to form a plurality of pinholes in the filter material. [Effects of the Invention]

[0013] This invention can suppress the adhesion of processing debris generated during the manufacturing of pinholes in a spatial filter to surrounding optical elements. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a perspective view showing an example of the configuration of a laser processing apparatus according to an embodiment. [Figure 2] Figure 2 is a schematic diagram showing the general configuration of the laser beam irradiation unit shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram showing the general configuration of the laser beam irradiation unit shown in Figure 1. [Figure 4] Figure 4 is an enlarged schematic diagram showing the focal point position of the lens in Figures 2 and 3. [Figure 5] Fig. 5 is a flowchart showing the flow of the laser processing method according to the embodiment. [Figure 6] Fig. 6 is a schematic diagram showing one state of the spatial filter manufacturing step shown in Fig. 5. [Figure 7] Fig. 7 is a perspective view schematically showing a main part in Fig. 6. [Figure 8] Fig. 8 is a perspective view schematically showing one state of a filter material in the laser processing step shown in Fig. 5. [Figure 9] Fig. 9 is a perspective view schematically showing one state of a filter material in the spatial filter manufacturing step after the step of Fig. 8. [Figure 10] Fig. 10 is a perspective view schematically showing one state of a filter material in the laser processing step after the step of Fig. 9. MODE FOR CARRYING OUT THE INVENTION

[0015] Modes (embodiments) for carrying out the present invention will be described in detail below with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. In addition, the constituent elements described below include those that can be easily conceived by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or modifications of the configuration can be made without departing from the gist of the present invention.

[0016] [Embodiment] <Configuration of laser processing apparatus 1> First, the configuration of a laser processing apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a configuration example of the laser processing apparatus 1 according to the embodiment. Fig. 2 and Fig. 3 are schematic diagrams showing a schematic configuration of a laser beam irradiation unit 20 shown in Fig. 1. Fig. 4 is an enlarged schematic diagram showing a focal point position 26 of a lens 31 in Fig. 2 and Fig. 3.

[0017] A laser processing apparatus 1 includes a holding table 10, a laser beam irradiation unit 20, a movement unit 60, an imaging unit 70, an input unit 80, and a control unit 90. In the following description, the X-axis direction is one direction on a horizontal plane. The Y-axis direction is a direction orthogonal to the X-axis direction on the horizontal plane. The Z-axis direction is a direction orthogonal to both 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 index feed direction is the Y-axis direction, and the focal point position adjustment direction is the Z-axis direction.

[0018] The laser processing apparatus 1 according to the embodiment is an apparatus that processes a workpiece 100 by irradiating a laser beam 21 onto the workpiece 100 to be processed. Processing of the workpiece 100 by the laser processing apparatus 1 includes, for example, modified layer forming processing for forming a modified layer inside the workpiece 100 by stealth dicing, groove processing for forming grooves on a surface 102 of the workpiece 100, or cutting processing for cutting the workpiece 100 along lines to divide 103, etc.

[0019] The workpiece 100 is, for example, a wafer such as a disk-shaped semiconductor device wafer or an optical device wafer having a substrate 101 made of silicon (Si), sapphire (Al2O3), gallium arsenide (GaAs), silicon carbide (SiC), lithium tantalate (LiTaO3), or the like. The workpiece 100 has lines to divide 103 set in a grid pattern on a surface 102 of the substrate 101, and devices 104 formed in regions divided by the lines to divide 103. The devices 104 are, for example, integrated circuits such as IC (Integrated Circuit) or LSI (Large Scale Integration), or image sensors such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor).

[0020] The workpiece 100 is transported and processed while supported within the opening of the frame 110, for example, with an annular frame 110 attached and a tape 111 with a larger diameter than the outer diameter of the workpiece 100 attached to the back surface 105 of the workpiece 100. The workpiece 100 is divided into individual devices 104 along the division line 103 and fragmented into chips. In this embodiment, the workpiece 100 is disc-shaped, but in this invention it does not have to be disc-shaped. Also, in this embodiment the chips are square-shaped, but in this invention they may be rectangular.

[0021] The holding table 10 holds the workpiece 100 on its holding surface 11. The holding surface 11 is a disc shape formed from porous ceramic or the like. In this 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. Multiple clamping parts 12 are arranged around the holding table 10 to hold an annular frame 110 that supports the workpiece 100.

[0022] The holding table 10 is rotated by a rotary unit 13 around an axis parallel to the Z-axis direction. The rotary unit 13 is supported by an X-axis direction moving plate 14. The rotary unit 13 and the holding table 10 are moved in the X-axis direction via the X-axis direction moving plate 14 by a machining feed unit 61, which will be described later. The rotary unit 13 and the holding table 10 are moved in the Y-axis direction via the X-axis direction moving plate 14, the machining feed unit 61, and the Y-axis direction moving plate 15 by an indexing feed unit 62, which will be described later.

[0023] The laser beam irradiation unit 20 is a unit that irradiates a workpiece 100 held on the holding surface 11 of the holding table 10 with a laser beam 21. Of the laser beam irradiation unit 20, at least the concentrator 23 (see Figures 2 and 3) is supported by a focusing point position adjustment unit 63, which will be described later and is installed on a column 3 erected from the main body 2 of the laser processing apparatus 1. As shown in Figures 2 and 3, the laser beam irradiation unit 20 includes a laser oscillator 22, a concentrator 23, a mirror 24, a spatial filter 30, and a box-shaped member 40.

[0024] The laser oscillator 22 emits a laser beam 21 having a predetermined wavelength for processing the workpiece 100 and the filter material 33 described later. The laser beam 21 irradiated by the laser beam irradiation unit 20 is a laser beam with a wavelength that is transparent to or absorbs the workpiece 100 and a laser beam with a wavelength that is absorbed by the filter material 33. The laser beam 21 is, for example, a CO2 laser.

[0025] The light concentrator 23 is a focusing lens that focuses 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 irradiates the workpiece 100 with the laser beam. The light concentrator 23 focuses the laser beam 21, from which optical noise has been removed by the spatial filter 30, onto the workpiece 100. The focusing point 25 of the laser beam 21 focused by the light concentrator 23 is positioned at a predetermined processing position on the workpiece 100.

[0026] The mirror 24 reflects the laser beam 21 and directs it toward the workpiece 100 held on the holding surface 11 of the holding table 10. In this embodiment, the mirror 24 also reflects the laser beam 21 that has passed through the spatial filter 30 toward the concentrator 23. Note that the arrangement of the optical system of the laser beam irradiation unit 20 is not limited to the examples shown in Figures 2 and 3; for example, multiple mirrors 24 may be arranged to guide the laser beam 21.

[0027] The spatial filter 30 is positioned between the laser oscillator 22 and the focuser 23 to remove optical noise from the laser beam 21 emitted from the laser oscillator 22. The spatial filter 30 includes lenses 31 and 32 and a filter material 33. In this embodiment, the spatial filter 30 is treated as including the lens 32, but generally the spatial filter 30 refers to a combination of the lens 31 and the filter material 33, and in this invention, it is not necessarily required to include the lens 32. The filter material 33 is fixed to a support table 34 that is movable in the direction of the optical axis of the laser beam 21 and in the in-plane direction perpendicular to the optical axis.

[0028] The laser beam 21 enters the lens 31 in the spatial filter 30, passes through the filter material 33, and exits from the lens 32. Lens 31 is a lens that focuses the laser beam 21 emitted from the laser oscillator 22 toward the filter material 33. The laser beam 21 focused by lens 31 is concentrated at the focal point position 26 and then diffuses. Lens 32 is a collimator lens positioned downstream of the focal point position 26 of lens 31 and causes the incident laser beam 21 to exit as parallel light. Lenses 31 and 32 constitute a Keplerian beam expander by combining convex lenses.

[0029] The filter material 33 is positioned at the focal point position 26 of the lens 31. More specifically, the filter material 33 is positioned at the focal point position 26-1 of the laser beam 21 focused by the lens 31 when the box-shaped member 40 (described later) is in a non-operating position 41 (the position shown in Figure 2). The filter material 33 is made of a material that can be laser-drilled and is resistant to deformation by heat, such as CuW (copper tungsten), SUS (stainless steel), or AlN (aluminum nitride).

[0030] The laser beam 21, focused by the lens 31, passes through a pinhole 35 (see Figure 6) formed at the focal point position 26-1 of the filter material 33, thereby removing optical noise. The pinhole 35 is a through-hole that penetrates in the direction of the optical axis of the laser beam 21, and is formed in the spatial filter manufacturing step 201 (see Figure 5) described later, when the box-shaped member 40 described later is in the operating position 42 (position shown in Figure 3).

[0031] The support table 34 supports the filter material 33. In the example shown in Figures 2 and 3, the support table 34 supports the lower edge of the filter material 33 on its upper surface. The support table 34 includes, for example, a moving mechanism (not shown) that supports the filter material 33 so that it can move in a direction perpendicular to the optical axis of the laser beam 21. This makes the filter material 33 movable in a direction perpendicular to the optical axis of the laser beam 21.

[0032] The box-shaped member 40 is movable back and forth between a non-operating position 41 (position shown in Figure 2), which is outside the optical path of the laser beam 21, and an operating position 42 (position shown in Figure 3), which is within the optical path of the laser beam 21 and covers the filter material 33. The box-shaped member 40 moves between the non-operating position 41 and the operating position 42 by a moving mechanism (not shown). The box-shaped member 40 has an opening 43, windows 44 and 45, and a suction port 46.

[0033] The opening 43 is formed on one side of the box-shaped member 40 (the bottom surface in the examples shown in Figures 2 and 3) and is a hole through which the filter material 33 passes when it is housed inside. The box-shaped member 40 houses the filter material 33 by moving, for example, in a plane direction perpendicular to the optical axis direction of the laser beam 21. When the box-shaped member 40 is in the operating position 42 (the position shown in Figure 3) and the filter material 33 is housed inside, the opening 43 is closed by the support table 34 that supports the filter material 33.

[0034] The windows 44 and 45 are formed on the optical path of the laser beam 21 when the box-shaped member 40 is in the operating position 42 (the position shown in Figure 3) and the filter material 33 is housed inside, and they transmit the laser beam 21. The windows 44 and 45 are made of, for example, BK7 (borosilicate crown glass), CaF2 (calcium fluoride), or SiO2 (synthetic quartz glass). The refractive index of the windows 44 and 45 differs depending on the material. Therefore, it is preferable that the thickness of the windows 44 and 45 be selected so that the focal point position 26 of the laser beam 21 is shifted by a predetermined distance. For example, if the window 44 is synthetic quartz glass with a thickness of 1 mm, the focal length of the lens 31 is f=50, and the wavelength of the laser beam 21 is 532 nm, the focal point position 26 will be shifted by about 0.3 mm.

[0035] As shown in Figure 4, the laser beam 21-2, focused by the lens 31 and incident on the window 44, is refracted upon entry and exit of the window 44, causing the focal point position 26 to change. That is, the focal point position 26-2 of the laser beam 21-2 that has passed through the window 44 is shifted to a position further back (away from the lens 31) than the focal point position 26-1 of the laser beam 21-1 which is not interfered with by the window 44. Therefore, the filter material 33 is irradiated with the laser beam 21 in a defocused state when the box-shaped member 40 is in its operating position 42 (the position shown in Figure 3) and is covered by the box-shaped member 40.

[0036] The suction port 46 is formed on one side of the box-shaped member 40 (the top surface in the examples shown in Figures 2 and 3) and communicates with the suction source 47. When the box-shaped member 40 is in the operating position 42 (the position shown in Figure 3), the opening 43 is closed by the filter material 33, thereby sealing the inside of the box-shaped member 40. In this state, by applying negative pressure to the suction source 47, the inside of the box-shaped member 40 is sucked through the suction port 46, and processing debris generated by the laser beam 21 irradiating the filter material 33 is discharged from the suction port 46.

[0037] The moving unit 60 shown in Figure 1 is a unit that moves the focal point 25 of the laser beam 21 (see Figures 2 and 3) and the workpiece 100 held on the holding table 10 relative to each other. The moving unit 60 includes a machining feed unit 61, an indexing feed unit 62, and a focal point position adjustment unit 63.

[0038] The processing feed unit 61 is a unit that moves the holding table 10 and the focusing point 25 of the laser beam irradiation unit 20 (see Figures 2 and 3) relative to each other 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 main body 2 of the laser processing apparatus 1. The processing feed unit 61 supports the X-axis direction moving plate 14 so as to be movable in the X-axis direction.

[0039] The indexing feed unit 62 is a unit that moves the holding table 10 and the focusing point 25 of the laser beam irradiation unit 20 (see Figures 2 and 3) relative to each other in the Y-axis direction, which is the indexing feed direction. In this embodiment, the indexing feed unit 62 moves the holding table 10 in the Y-axis direction. In this embodiment, the indexing feed unit 62 is installed on the main body 2 of the laser processing apparatus 1. The indexing feed unit 62 supports the Y-axis movement plate 15 so as to be movable in the Y-axis direction.

[0040] The focusing point position adjustment unit 63 is a unit that moves the holding table 10 and the focusing point 25 of the laser beam irradiation unit 20 (see Figures 2 and 3) relative to each other in the Z-axis direction, which is the direction of focusing point position adjustment. In the embodiment, the focusing 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 focusing point position adjustment unit 63 is installed on a column 3 erected from the main body 2 of the laser processing apparatus 1. The focusing 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.

[0041] The machining feed unit 61, the indexing feed unit 62, and the focusing point position adjustment unit 63 each include, in embodiments, a well-known ball screw, a well-known pulse motor, and a well-known guide rail. The ball screw is rotatably mounted around its axis. The pulse motor rotates the ball screw around its axis. The guide rail of the machining 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 machining feed unit 61 is fixedly mounted on 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 fixedly mounted on the main body 2 of the apparatus. The guide rail of the focusing point position adjustment 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 focusing point position adjustment unit 63 is fixedly mounted on the column 3.

[0042] The imaging unit 70 images the workpiece 100 held on the holding table 10. The imaging unit 70 includes a CCD camera or an infrared camera. The imaging unit 70 is fixed, for example, adjacent to the light concentrator 23 of the laser beam irradiation unit 20 (see Figures 2 and 3). The imaging unit 70 images the workpiece 100 to obtain an image for performing alignment to position the workpiece 100 and the laser beam irradiation unit 20, and outputs the obtained image.

[0043] In this 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 from the operator, such as registering processing content information. The input unit 80 may also be an external input device such as a keyboard.

[0044] The control unit 90 controls each of the above-mentioned components of the laser processing apparatus 1 to cause the laser processing apparatus 1 to perform processing operations on the workpiece 100. The control unit 90 is a computer that includes an arithmetic processing unit as a means of calculation, a storage device as a means of storage, and an input / output interface device as a means of communication. The arithmetic processing unit includes, for example, a microprocessor such as a CPU (Central Processing Unit). The storage device has memory such as an HDD (Hard Disk Drive), ROM (Read Only Memory), or RAM (Random Access Memory). The arithmetic processing unit performs various calculations based on a predetermined program stored in the storage device. The arithmetic processing unit outputs various control signals to each of the above-mentioned components via the input / output interface device according to the calculation results, thereby controlling the laser processing apparatus 1.

[0045] The control unit 90 drives a moving mechanism (not shown) to move the box-shaped member 40 between a non-operating position 41 and an operating position 42. The control unit 90 positions the box-shaped member 40 at the operating position 42 and applies negative pressure using a suction source 47 to draw suction into the inside of the box-shaped member 40, while irradiating it with the laser beam 21. The laser beam 21 is irradiated onto the filter material 33 in a defocused state, forming pinholes 35 in the filter material 33. This manufactures a spatial filter 30 including lenses 31 (, 32) and filter material 33. The control unit 90 also positions the box-shaped member 40 at the non-operating position 41 and irradiates the workpiece 100 held on the holding table 10 with the laser beam 21 to process the workpiece 100.

[0046] <Laser processing method> Next, the flow of the laser processing method according to an embodiment of the present invention will be described based on the drawings. Figure 5 is a flowchart showing the flow of the laser processing method according to an embodiment. As shown in Figure 5, the laser processing method of the embodiment comprises a spatial filter manufacturing step 201 and a laser processing step 202.

[0047] Figure 6 is a schematic diagram showing one state of the spatial filter manufacturing step 201 shown in Figure 5. Figure 7 is a schematic perspective view showing the main parts in Figure 6. Note that in Figure 6, the support table 34 and the box-shaped member 40, excluding windows 44 and 45, are not depicted. Also, in Figure 7, the support table 34 is not depicted.

[0048] Furthermore, in the following figures, the optical axis direction of the laser beam 21 is defined as the z-axis direction, one direction of the plane perpendicular to the optical axis direction is defined as the x-axis direction, and the direction perpendicular to the x-axis direction of the plane perpendicular to the optical axis direction is defined as the y-axis direction. The z-axis direction, x-axis direction, and y-axis direction correspond to the Z-axis direction, X-axis direction, and Y-axis direction of the laser processing apparatus 1 when the laser beam 21 guided to each optical system in the laser beam irradiation unit 20 irradiates the workpiece 100 held on the holding table 10 (see Figure 1).

[0049] The spatial filter manufacturing step 201 is a step in manufacturing a spatial filter 30 including a lens 31 and a filter material 33 by forming a pinhole 35 in the filter material 33. In the spatial filter manufacturing step 201, first, as shown in Figure 2, with the box-shaped member 40 positioned in a non-operating position 41, the lens 31 is placed between the laser oscillator 22 and the light condenser 23, and the filter material 33 is placed at the focal point position 26-1 of the lens 31.

[0050] In the spatial filter manufacturing step 201, as shown in Figure 3, the control unit 90 (see Figure 1) drives a moving mechanism (not shown) to move the box-shaped member 40, positioning it at the working position 42 where it covers the filter material 33. Next, a negative pressure is applied by the suction source 47 to draw suction into the inside of the box-shaped member 40, while a laser beam 21 is emitted from the laser oscillator 22.

[0051] The laser beam 21 emitted from the laser oscillator 22 is focused by the lens 31, passes through the window 44, and then irradiates the filter material 33. The laser beam 21 that has passed through the window 44 (laser beam 21-2 shown in Figure 4) irradiates the filter material 33 in a defocused state because the focal point position 26 changes due to refraction at the time of entry and exit in the window 44.

[0052] The laser beam 21 irradiates the filter material 33, creating a hole at the focal point position 26-1 (see Figure 2, etc.), forming a pinhole 35 that is larger than the focal diameter of the laser beam 21. This forms a spatial filter 30 including the lens 31 (, 32) and the filter material 33 with the pinhole 35 formed therein. In Figure 3, the laser beam 21 is shown irradiating the workpiece 100 for comparison with Figure 2, but during the spatial filter manufacturing step 201, it is preferable to configure the system to receive the laser beam 21 using a power meter located adjacent to the holding table 10, for example.

[0053] The laser processing step 202 is a step in which the workpiece 100 is processed by irradiating the workpiece 100 with a laser beam 21 through a pinhole 35 of the spatial filter 30. After manufacturing the spatial filter 30 and stopping the irradiation of the laser beam 21, in the laser processing step 202, the control unit 90 (see Figure 1) drives a moving mechanism (not shown) to move the box-shaped member 40 to a non-working position 41 (position shown in Figure 2) outside the optical path of the laser beam 21. As a result, the focal point position 26 of the laser beam 21, which is focused by the lens 31, returns to the position where the filter material 33 is placed, that is, to the focal point position 26-1, which is the center of the pinhole 35. The laser processing step 202 then proceeds to emit the laser beam 21 from the laser oscillator 22.

[0054] The laser beam 21 emitted from the laser oscillator 22 is focused by the lens 31 and passes through the pinhole 35 formed in the filter material 33 without passing through the window 44. After passing through the pinhole 35, the optical noise of the laser beam 21 is removed, and as shown in Figure 2, it passes through the lens 32 to become parallel light, which is reflected by the mirror 24, focused by the light concentrator 23, and irradiated onto the workpiece 100.

[0055] Here, as mentioned above, Patent Document 1 discloses a spatial filter in which multiple pinholes are formed in advance in the filter material, and if one pinhole deteriorates, another pinhole can be used. In this embodiment as well, when a pinhole 35 formed in the filter material 33 deteriorates, a method of forming and using another pinhole 35 will be described.

[0056] Figure 8 is a schematic perspective view showing one state of the filter material 33 in the laser processing step 202 shown in Figure 5. In Figure 8, multiple pinholes 35 have already been formed, and the laser beam 21 is irradiating one of them, pinhole 35-1. In the laser processing step 202 shown in Figure 8, if pinhole 35-1 deteriorates, the irradiation of the laser beam 21 is stopped, and the process proceeds back to the spatial filter manufacturing step 201.

[0057] Figure 9 is a schematic perspective view showing one state of the filter material 33 in the spatial filter manufacturing step 201 following Figure 8. In the spatial filter manufacturing step 201, the box-shaped member 40 is moved to an operating position 42 that covers the filter material 33 (see Figure 3). Next, a moving mechanism (not shown) is driven to move the filter material 33 a predetermined distance in a direction perpendicular to the optical axis direction of the laser beam 21 (in the example shown in Figure 9, the negative direction of the x-axis). This positions the focal point position 26-2 of the laser beam 21 at a position where a new pinhole 35-2 is formed in the filter material 33.

[0058] In the spatial filter manufacturing step 201, a negative pressure is then applied by the suction source 47 to draw suction into the inside of the box-shaped member 40, while a laser beam 21 is emitted from the laser oscillator 22 (see Figure 3, etc.). As shown in Figure 9, the laser beam 21 is irradiated in a defocused state onto the focal point position 26-2 of the filter material 33. As a result, a pinhole 35-2 (see Figure 10) is formed at the focal point position 26-2.

[0059] In this way, in the spatial filter manufacturing step 201, multiple pinholes 35 can be formed in the filter material 33 by moving the filter material 33 in a direction perpendicular to the optical axis direction of the laser beam 21. Once a new pinhole 35-2 is formed, the irradiation of the laser beam 21 is stopped and the process proceeds again to the laser processing step 202.

[0060] Figure 10 is a schematic perspective view showing one state of the filter material 33 in the laser processing step 202 following Figure 9. In the laser processing step 202, the box-shaped member 40 is moved to the non-operating position 41 (see Figure 2). As a result, the focal point position 26-1 of the laser beam 21 is positioned at the newly formed pinhole 35-2 in the filter material 33.

[0061] In the laser processing step 202, the laser beam 21 is then emitted from the laser oscillator 22. As shown in Figure 10, the laser beam 21 is focused toward the focal point position 26-1, which is the center of the pinhole 35-2 in the filter material 33, and passes through the pinhole 35-2. As a result, the optical noise of the laser beam 21 is removed by the newly formed pinhole 35-2.

[0062] As described above, in the laser processing apparatus 1 according to this embodiment, when irradiating the filter material 33 with a laser beam 21 to manufacture pinholes 35, a box-shaped member 40 having windows 44, 45 through which the laser beam 21 passes is placed in a position that covers the filter material 33, and processing is performed while suction is applied to the inside of this box-shaped member 40. Therefore, pinholes 35 of the spatial filter 30 can be manufactured without adhering processing debris to the surrounding optical elements. Thus, it is possible to achieve high-precision alignment and suppress the risk of degrading processing quality.

[0063] Furthermore, by changing the focal point position 26 using the window 44, a pinhole 35 is formed in a defocused state. In other words, since the position of the filter material 33 is not moved in the optical axis direction from the formation of the pinhole 35 to the processing of the workpiece 100, higher precision processing can be achieved.

[0064] [Variation] The modified version differs from the embodiment in that only the windows 44 and 45 are able to move back and forth along the optical path of the laser beam 21. That is, the box-shaped member 40 does not necessarily have to move back and forth along the optical path of the laser beam 21; it is sufficient that at least the window 44 for shifting the focal point position 26 of the laser beam 21 is able to move back and forth.

[0065] In this case, for example, the box-shaped member 40 is positioned to cover the filter material 33 within the optical path of the laser beam 21 shown in Figure 3. The box-shaped member 40 has openings instead of windows 44 and 45 where windows 44 and 45 are formed in the embodiment. The windows 44 and 45 are provided to move back and forth between a position where the openings are open and a position where they are closed.

[0066] In other words, the position where windows 44 and 45 open is the non-operating position, and the position where they are closed is the operating position. In the modified laser processing method, the spatial filter manufacturing step 201 is performed with windows 44 and 45 positioned in the operating position, and the laser processing step 202 is performed with windows 44 and 45 positioned in the non-operating position.

[0067] It should be noted that the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core principles of the present invention.

[0068] For example, in the spatial filter manufacturing step 201, the size of the pinhole 35 to be formed may be adjusted by moving the filter material 33 in a spiral manner in the xy plane perpendicular to the optical axis. Alternatively, the focal point position 26 of the laser beam 21 may be changed by shifting the position of the lens 31 in the direction of the optical axis.

[0069] Furthermore, the box-shaped member 40 only needs to have at least a window 44 through which the laser beam 21 passes before being irradiated onto the filter material 33, and does not need to have a window 45. Also, the laser beam irradiation unit 20 may have another pinhole larger in diameter than the pinhole 35 in front of the lens 31. By passing the laser beam 21 through the pinhole before it enters the lens 31, a cleaner laser beam 21 can be formed.

[0070] Alternatively, a beam profiler may be installed at the processing point where the laser beam 21 irradiates the workpiece 100 on the holding table 10, and the state of the laser beam 21 may be determined by this profiler to automatically determine whether or not it is necessary to manufacture a new pinhole 35. Such automatic determination can be achieved, for example, by saving a reference image of the laser beam 21 in advance and detecting changes in the state of the laser beam 21 through pattern matching or the like. [Explanation of Symbols]

[0071] 1. Laser processing device 10 Retention Table 20 Laser beam irradiation unit 21 Laser beam 22 Laser Oscillator 23. Light concentrator 24 Mirror 25 Focusing points 26 Focus point position 30 Spatial Filters 31, 32 lenses 33 Filter materials 34 Support Table 35 pinholes 40 Box-shaped member 41 Non-active position 42 Working position 43 Aperture 44, 45 windows 46 Suction port 47 Suction source 60 Mobile Units 90 Control Unit 100 Workpiece

Claims

1. A laser processing apparatus that processes a workpiece by irradiating it with a laser beam, A holding table for holding the workpiece, A laser beam irradiation unit that emits a laser beam, A moving unit that moves the focusing point of the laser beam and the workpiece held on the holding table relative to each other, A control unit that controls each component, Equipped with, The laser beam irradiation unit is Laser oscillator and, A focusing device that concentrates the laser beam emitted from the laser oscillator and irradiates it onto the workpiece, A lens disposed between the laser oscillator and the light condenser, A filter material is placed at the focal point of the lens, A box-shaped member having a suction port that communicates with a suction source, It has, The box-shaped member is, The device is movable back and forth between a non-operating position, which is outside the optical path of the laser beam, and an operating position, which is within the optical path of the laser beam and covers the filter material, and further has a window that transmits the laser beam at the operating position. The control unit is, By positioning the box-shaped member at the working position and suctioning the inside of the box-shaped member, the laser beam is irradiated onto the filter material through the window to form pinholes in the filter material, thereby manufacturing a spatial filter including the lens and the filter material. With the box-shaped member positioned in the non-operating position, the laser beam is directed onto the workpiece held on the holding table to perform processing on the workpiece. A laser processing apparatus characterized by the following features.

2. A laser processing apparatus that processes a workpiece by irradiating it with a laser beam, A holding table for holding the workpiece, A laser beam irradiation unit that emits a laser beam, A moving unit that moves the focusing point of the laser beam and the workpiece held on the holding table relative to each other, A control unit that controls each component, Equipped with, The laser beam irradiation unit is Laser oscillator and, A focusing device that concentrates the laser beam emitted from the laser oscillator and irradiates it onto the workpiece, A lens disposed between the laser oscillator and the light condenser, A filter material is placed at the focal point of the lens, A box-shaped member having a suction port that communicates with a suction source and positioned to cover the filter material within the optical path of the laser beam, It has, The box-shaped member is, An aperture through which the laser beam passes, A window that is movable back and forth between a non-operating position, which is the position in which the opening is open, and an operating position, which is the position in which the opening is closed, and which transmits the laser beam in the operating position, It further possesses, The control unit is, By positioning the window at the operating position and suctioning the inside of the box-shaped member, the laser beam is irradiated onto the filter material through the window to form a pinhole in the filter material, thereby manufacturing a spatial filter including the lens and the filter material. With the window positioned in the non-operating position, the laser beam is directed onto the workpiece held on the holding table to perform machining on the workpiece. A laser processing apparatus characterized by the following features.

3. The filter material is movable in a direction perpendicular to the optical axis of the laser beam. A laser processing apparatus according to claim 1 or 2, characterized in that

4. A laser processing method in which a laser beam emitted from a laser oscillator is focused by a light condenser and irradiated onto a workpiece to perform processing, A spatial filter manufacturing step involves arranging a lens between the laser oscillator and the light condenser, arranging a filter material at the focal point of the lens, and then emitting a laser beam from the laser oscillator to form a pinhole in the filter material, thereby manufacturing a spatial filter including the lens and the filter material. A laser processing step in which a workpiece is processed by irradiating the workpiece with the laser beam through the pinhole of the spatial filter, Equipped with, In the spatial filter manufacturing step, A box-shaped member having a window through which the laser beam passes is positioned to cover the filter material, and the laser beam is irradiated onto the filter material through the window while suction is applied to the inside of the box-shaped member. A laser processing method characterized by the following features.

5. In the spatial filter manufacturing step, By moving the filter material in a direction perpendicular to the optical axis of the laser beam, multiple pinholes are formed in the filter material. The laser processing method according to claim 4, characterized in that

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