Laser processing apparatus

Abstract

To provide a laser processing device which achieves high operation efficiency.SOLUTION: A laser processing device processes a workpiece 11 by radiation of a laser beam 48 and includes a laser radiation unit 44 which radiates the laser beam 48 to the workpiece 11 held by a holding unit 28 including a holding surface 28a. The laser radiation unit 44 includes: a condensing lens 68 which condenses the laser beam 48 emitted from a laser oscillator 60; and a foreign object adhesion prevention unit 70 which prevents adhesion of foreign objects to the condensing lens 68. The foreign object adhesion prevention unit 70 includes: a protection film 72 disposed between the holding surface 28a and the condensing lens 68 and allows the laser beam 48 to penetrate thereinto; a first roller 76A to which one end side of the protection film 72 is fixed and which rotates to send out the protection film 72; and a second roller 76B to which the other end side of the protection film 72 is fixed and which rotates to take up the protection film 72.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a laser processing apparatus that processes a workpiece by irradiating a laser beam.

Background Art

[0002] In the manufacturing process of device chips, a wafer in which devices are formed in a plurality of regions partitioned by a plurality of streets (division planned lines) arranged in a grid pattern is used. By dividing this wafer along the streets, a plurality of device chips each having a device can be obtained. The device chips are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] For wafer dicing, a cutting apparatus that cuts a workpiece with an annular cutting blade is used. On the other hand, in recent years, the development of a process for dicing a wafer by laser processing using a laser processing apparatus has also been advanced. The laser processing apparatus includes a holding unit (chuck table) that holds the workpiece and a laser irradiation unit that irradiates the workpiece with a laser beam. The wafer is held by the holding unit, and the wafer is laser processed by irradiating a laser beam from the laser irradiation unit toward the wafer.

[0004] For example, Patent Document 1 discloses a processing method in which a laser processing groove is formed along a street in a wafer by irradiating a laser beam. When an external force is applied to the wafer in which the laser processing groove is formed along the street, the laser processing groove functions as a division starting point, and the wafer is divided along the street.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The laser irradiation unit mounted on the laser processing apparatus includes a condenser lens that condenses a laser beam at a predetermined position. When processing a workpiece with the laser processing apparatus, the condenser lens is positioned so as to face the workpiece. For example, the laser beam is irradiated so as to be condensed on the surface or inside of the workpiece.

[0007] Here, for example, when ablation processing is performed on a workpiece by irradiating a laser beam, the melt of the workpiece becomes debris (processing chips) and scatters. In addition, there may be minute particles and mist floating in the processing chamber where the workpiece is processed. When such foreign matter adheres to the condenser lens, the laser beam may not be irradiated onto the workpiece under the intended conditions, and there is a risk of processing defects. Therefore, when foreign matter adheres to the condenser lens, the condenser lens is cleaned or replaced.

[0008] However, when cleaning or replacing the condenser lens, careful handling of the condenser lens is required so as not to affect the characteristics of the condenser lens due to scratches or the like. In addition, when mounting the condenser lens on the laser irradiation unit, it is necessary to precisely adjust the position and orientation of the condenser lens so that the laser beam is condensed at a desired position. Therefore, attaching and detaching the condenser lens is time-consuming and causes a decrease in the operating efficiency of the laser processing apparatus.

[0009] Note that a cover that covers the surface side of the condenser lens facing the workpiece may be attached to the laser irradiation unit. The cover is formed of glass or the like that is transparent to the laser beam, and the laser beam that has passed through the condenser lens passes through the cover and irradiates the workpiece. This cover prevents foreign matter from adhering to the condenser lens and reduces the frequency of cleaning or replacing the condenser lens.

[0010] When a foreign object of a predetermined amount or more adheres to the cover, the cover is cleaned or replaced so as not to adversely affect the laser processing. Since the cover is less expensive and easier to attach and detach than the condenser lens, excessive labor and cost are not required for cleaning or replacing the cover. However, as long as the cleaning or replacement of the cover is performed regularly, the processing of the workpiece by the laser processing apparatus cannot be avoided from being interrupted, and there is a limit to the operating efficiency of the laser processing apparatus.

[0011] The present invention has been made in view of such problems, and an object thereof is to provide a laser processing apparatus with high operating efficiency.

Means for Solving the Problems

[0012] According to one aspect of the present invention, there is provided a laser processing apparatus for processing a workpiece by irradiating a laser beam, comprising: a holding unit including a holding surface for holding the workpiece; and a laser irradiation unit for irradiating the laser beam onto the workpiece held by the holding unit. The laser irradiation unit includes a laser oscillator, a condenser lens for condensing the laser beam emitted from the laser oscillator, and a foreign matter adhesion prevention unit for preventing foreign matter from adhering to the condenser lens. The foreign matter adhesion prevention unit is disposed between the holding surface and the condenser lens, and includes a protective film having transparency to the laser beam, a first roller having one end side of the protective film fixed thereto and feeding out the protective film by rotation, a rotatable first pulley for supporting the protective film fed out from the first roller, a second roller having the other end side of the protective film fixed thereto and winding up the protective film by rotation, and a rotatable second pulley for supporting the protective film wound around the second roller. , The condenser lens is disposed below the holding surface, and the traveling path of the laser beam irradiated on the workpiece is inclined with respect to the vertical direction. A laser processing apparatus is provided.

[0013] In addition , The The protective film may be a polyolefin film or a polyester film. Further, the foreign matter adhesion prevention unit may further include a first rotation drive source for rotating the first roller and a second rotation drive source for rotating the second roller.

Effects of the Invention

[0014] In the laser irradiation unit of the laser processing apparatus according to one aspect of the present invention, a foreign matter adhesion prevention unit is mounted, which includes a protective film disposed between the holding surface of the holding unit and the condenser lens, a first roller for feeding out the protective film, and a second roller for winding up the protective film. Then, the adhesion of foreign matter to the condenser lens is prevented by the protective film, and the protective film can be easily moved by the first roller and the second roller.

[0015] By mounting the above-described foreign matter adhesion prevention unit on the laser irradiation unit, it is possible to easily and quickly position the protective film without foreign matter adhered thereto at a position overlapping the condenser lens. As a result, it is possible to avoid the processing of the workpiece by the laser processing apparatus being interrupted for a long time due to the foreign matter removal operation, and the operating efficiency of the laser processing apparatus is improved.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0017] Hereinafter, an embodiment according to an aspect of the present invention will be described with reference to the accompanying drawings. First, a configuration example of a laser processing apparatus according to this embodiment will be described. FIG. 1 is a perspective view showing a laser processing apparatus 2. In FIG. 1, the X-axis direction (processing feed direction, first horizontal direction) and the Y-axis direction (indexing feed direction, second horizontal direction) are perpendicular to each other. Also, the Z-axis direction (height direction, vertical direction, up and down direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0018] The laser processing apparatus 2 includes a base 4 that supports each component constituting the laser processing apparatus 2. The upper surface of the base 4 is a flat surface generally parallel to the horizontal direction (XY plane direction), and a moving mechanism (moving unit) 6 is provided on the upper surface of the base 4. The moving mechanism 6 includes a Y-axis moving mechanism (Y-axis moving unit) 8, an X-axis moving mechanism (X-axis moving unit) 18, and a Z-axis moving mechanism (Z-axis moving unit) 32.

[0019] The Y-axis moving mechanism 8 includes a pair of Y-axis guide rails 10 arranged along the Y-axis direction on the upper surface of the base 4. A flat plate-shaped Y-axis moving table 12 is slidably mounted on the pair of Y-axis guide rails 10 along the Y-axis guide rails 10.

[0020] A nut portion (not shown) is provided on the back surface (lower surface) side of the Y-axis moving table 12. A Y-axis ball screw 14 arranged along the Y-axis direction is screwed into this nut portion between the pair of Y-axis guide rails 10. Also, a Y-axis pulse motor 16 for rotating the Y-axis ball screw 14 is connected to the end of the Y-axis ball screw 14. When the Y-axis ball screw 14 is rotated by the Y-axis pulse motor 16, the Y-axis moving table 12 moves in the Y-axis direction along the Y-axis guide rails 10.

[0021] The X-axis moving mechanism 18 includes a pair of X-axis guide rails 20 arranged along the X-axis direction on the front surface (upper surface) side of the Y-axis moving table 12. A plate-shaped X-axis moving table 22 is slidably mounted on the pair of X-axis guide rails 20 along the X-axis guide rails 20.

[0022] On the back surface (lower surface) side of the X-axis moving table 22, a nut portion (not shown) is provided. A nut portion is screwed with an X-axis ball screw 24 disposed along the X-axis direction between a pair of X-axis guide rails 20. Further, an X-axis pulse motor 26 for rotating the X-axis ball screw 24 is connected to an end portion of the X-axis ball screw 24. When the X-axis ball screw 24 is rotated by the X-axis pulse motor 26, the X-axis moving table 22 moves in the X-axis direction along the X-axis guide rails 20.

[0023] On the surface (upper surface) of the X-axis moving table 22, a holding unit (holding table, chuck table) 28 for holding a workpiece 11 (see FIG. 2), which is an object to be processed by the laser processing apparatus 2, is provided. Further, around the holding unit 28, a plurality of clamps 30 for gripping and fixing an annular frame 17 (see FIG. 2) that supports the workpiece 11 are provided.

[0024] The upper surface of the holding unit 28 is a flat surface substantially parallel to the horizontal direction (XY plane direction), and constitutes a holding surface 28a for holding the workpiece 11. The holding surface 28a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), etc. formed inside the holding unit 28.

[0025] When the Y-axis moving table 12 is moved along the Y-axis direction, the holding unit 28 moves along the Y-axis direction. Further, when the X-axis moving table 22 is moved along the X-axis direction, the holding unit 28 moves along the X-axis direction. Further, a rotational drive source (not shown) such as a motor for rotating the holding unit 28 around a rotation axis substantially parallel to the Z-axis direction is connected to the holding unit 28.

[0026] At the rear end of the base 4 (behind the Y-axis moving mechanism 8, the X-axis moving mechanism 18, and the holding unit 28), a Z-axis moving mechanism 32 is provided. The Z-axis moving mechanism 32 includes a support structure 34 disposed on the upper surface of the base 4. The support structure 34 includes a rectangular parallelepiped-shaped base portion 34a fixed to the base 4 and a columnar support portion 34b protruding upward from an end of the base portion 34a. The surface (side surface) of the support portion 34b is formed in a planar shape along the Z-axis direction.

[0027] On the surface of the support portion 34b, a pair of Z-axis guide rails 36 are provided along the Z-axis direction. A flat plate-shaped Z-axis moving plate 38 is mounted on the pair of Z-axis guide rails 36 in a slidable state along the Z-axis guide rails 36.

[0028] On the back surface side of the Z-axis moving plate 38, a nut portion (not shown) is provided. A Z-axis ball screw (not shown) disposed along the Z-axis direction between the pair of Z-axis guide rails 36 is screwed into this nut portion. Further, at an end of the Z-axis ball screw, a Z-axis pulse motor 40 for rotating the Z-axis ball screw is connected. Furthermore, a support member 42 is fixed to the front surface side of the Z-axis moving plate 38. When the Z-axis ball screw is rotated by the Z-axis pulse motor 40, the Z-axis moving plate 38 and the support member 42 move in the Z-axis direction along the Z-axis guide rails 36.

[0029] The support member 42 supports a laser irradiation unit 44. The laser irradiation unit 44 includes a laser processing head 46 and irradiates a laser beam 48 toward a workpiece 11 (see FIG. 2) held by the holding unit 28 from the laser processing head 46. Thereby, laser processing is performed on the workpiece 11.

[0030] In addition, an imaging unit 50 capable of imaging the workpiece 11 and the like held by the holding unit 28 is attached to the laser irradiation unit 44. The imaging unit 50 includes a visible light camera including an imaging element that receives visible light and converts it into an electrical signal, an infrared camera including an imaging element that receives infrared light and converts it into an electrical signal, and the like. The image obtained by imaging the workpiece 11 with the imaging unit 50 is used for alignment between the holding unit 28 and the laser processing head 46 and the like.

[0031] When the Z-axis moving plate 38 is moved along the Z-axis direction, the laser processing head 46 and the imaging unit 50 move (ascend and descend) along the Z-axis direction. Thereby, adjustment of the condensing position of the laser beam 48 and focusing of the imaging unit 50 are performed.

[0032] The moving mechanism 6 is constituted by the Y-axis moving mechanism 8, the X-axis moving mechanism 18, and the Z-axis moving mechanism 32. The moving mechanism 6 relatively moves the holding unit 28, the laser beam 48 irradiated from the laser processing head 46, and the imaging unit 50 along the processing feed direction (X-axis direction) and the indexing feed direction (Y-axis direction).

[0033] In addition, the laser processing apparatus 2 includes a display unit (display section, display device) 52 that displays various types of information regarding the laser processing apparatus 2. For example, a touch panel is used as the display unit 52, and an operation screen for operating the laser processing apparatus 2 is displayed on the touch panel.

[0034] The operator of the laser processing apparatus 2 can input information to the laser processing apparatus 2 by touch-operating the touch panel. That is, the touch panel also functions as an input unit (input section, input device) for inputting various types of information to the laser processing apparatus 2 and is used as a user interface. However, the input unit may be a separately provided mouse, keyboard, or the like that is independent of the display unit 52.

[0035] Furthermore, the laser processing apparatus 2 includes a control unit (control section, control device) 54 that controls the laser processing apparatus 2. The control unit 54 is connected to each component (moving mechanism 6, holding unit 28, clamp 30, laser irradiation unit 44, imaging unit 50, display unit 52, etc.) that constitutes the laser processing apparatus 2. The control unit 54 operates the laser processing apparatus 2 by outputting a control signal to each component of the laser processing apparatus 2.

[0036] For example, the control unit 54 is constituted by a computer. Specifically, the control unit 54 includes an arithmetic unit that performs various calculations necessary for the operation of the laser processing apparatus 2, and a storage unit that stores various information (data, programs, etc.) used for the operation of the laser processing apparatus 2. The arithmetic unit is constituted to include a processor such as a CPU (Central Processing Unit). Further, the storage unit is constituted to include memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

[0037] Laser processing is performed on the workpiece 11 by the laser processing apparatus 2. FIG. 2 is a perspective view showing the workpiece 11. For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as single-crystal silicon, and includes surfaces 11a and 11b that are generally parallel to each other. The workpiece 11 is partitioned into a plurality of rectangular regions by a plurality of streets (division planned lines) 13 arranged in a lattice pattern so as to intersect each other.

[0038] On the surface 11a side of each of the plurality of regions partitioned by the streets 13, devices 15 such as IC (Integrated Circuit), LSI (Large Scale Integration), LED (Light Emitting Diode), and MEMS (Micro Electro Mechanical Systems) devices are formed. By dividing the workpiece 11 along the streets 13, a plurality of device chips each having a device 15 are obtained.

[0039] However, there are no restrictions on the type, material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a wafer of any shape and size made of a semiconductor other than silicon (such as GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. Also, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device 15, and the device 15 may not be formed on the workpiece 11.

[0040] When processing the workpiece 11 with the laser processing apparatus 2, for the convenience of handling (conveying, holding, etc.) the workpiece 11, the workpiece 11 is supported by an annular frame 17. The frame 17 is made of a metal such as SUS (stainless steel), and a circular opening 17a that penetrates the frame 17 in the thickness direction is provided at the central portion of the frame 17. Note that the diameter of the opening 17a is larger than the diameter of the workpiece 11.

[0041] A circular tape 19 is attached to the workpiece 11 and the frame 17. For example, the tape 19 includes a film-like base material formed in a circular shape and an adhesive layer (paste layer) provided on the base material. The base material is made of a resin such as polyolefin, polyvinyl chloride, polyethylene terephthalate, etc. Also, the adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive, etc. Note that an ultraviolet curable resin that cures by irradiation with ultraviolet rays may be used for the adhesive layer.

[0042] With the workpiece 11 disposed inside the opening 17a of the frame 17, when the central portion of the tape 19 is attached to the back surface 11b side of the workpiece 11 and the outer peripheral portion of the tape 19 is attached to the frame 17, the workpiece 11 is supported by the frame 17 via the tape 19.

[0043] Next, the laser irradiation unit 44 mounted on the laser processing apparatus 2 will be described. FIG. 3 is a partial cross-sectional front view showing the holding unit 28 and the laser irradiation unit 44.

[0044] When processing the workpiece 11 with the laser processing apparatus 2, the workpiece 11 is held by the holding unit 28. For example, when performing laser processing on the surface 11a side of the workpiece 11, the workpiece 11 is placed on the holding unit 28 such that the surface 11a side is exposed upward and the back surface 11b side (the tape 19 side) faces the holding surface 28a. Further, the frame 17 is fixed by a plurality of clamps 30 (see FIG. 1). In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 28a, the workpiece 11 is suction-held by the holding unit 28 via the tape 19.

[0045] The laser irradiation unit 44 includes a laser oscillator 60 such as a YAG laser or a YVO4 laser, and an adjuster 62 such as an attenuator that adjusts the power of the laser beam 48 emitted from the laser oscillator 60. Further, the laser irradiation unit 44 includes an optical system 64 that guides the laser beam 48 to the workpiece 11 held by the holding unit 28. The optical system 64 is configured to include a plurality of optical elements and controls the traveling direction, shape, etc. of the laser beam 48.

[0046] Specifically, the optical system 64 includes a mirror 66 that reflects the laser beam 48 and a condenser lens 68 that condenses the laser beam 48. The condenser lens 68 is held inside the laser processing head 46, and the lower surface side of the condenser lens 68 faces the holding surface 28a of the holding unit 28.

[0047] The laser beam 48 emitted from the laser oscillator 60 and having its power adjusted by the adjuster 62 is reflected by the mirror 66 and enters the condenser lens 68, and is condensed at a predetermined position by the condenser lens 68. For example, the laser beam 48 is condensed on the surface 11a or inside the workpiece 11 to perform laser processing on the workpiece 11.

[0048] The irradiation conditions of the laser beam 48 are set according to the content of the laser processing to be performed on the workpiece 11. For example, when performing ablation processing on the workpiece 11, the wavelength of the laser beam 48 is set so that at least a part of the laser beam 48 is absorbed by the workpiece 11. That is, a laser beam having absorbability with respect to the workpiece 11 is used as the laser beam 48. In addition, other irradiation conditions of the laser beam 48 (average output, repetition frequency, processing feed rate, etc.) are also appropriately set so that ablation processing is performed on the workpiece 11.

[0049] For example, when the workpiece 11 is a silicon wafer and ablation processing is performed on the silicon wafer, the irradiation conditions of the laser beam 48 can be set as follows. Wavelength: 355 nm Average output: 2 W Repetition frequency: 200 kHz Processing feed rate: 400 mm / s

[0050] While condensing the laser beam 48 on the surface 11a or inside of the workpiece 11 and moving the holding unit 28 along the processing feed direction (X-axis direction), the holding unit 28 and the laser beam 48 move relatively, and the laser beam 48 is scanned along the processing feed direction. As a result, ablation processing is performed on the workpiece 11, and linear laser processing grooves are formed on the surface 11a side of the workpiece 11.

[0051] For example, by forming laser processing grooves extending from the surface 11a to the back surface 11b of the workpiece 11 along all the streets 13 (see FIG. 2), the workpiece 11 is divided along the streets 13. In addition, after forming laser processing grooves having a depth less than the thickness of the workpiece 11 on the surface 11a side of the workpiece 11 along all the streets 13, the back surface 11b side of the workpiece 11 is ground with a grinding wheel to expose the laser processing grooves on the back surface 11b of the workpiece 11, whereby the workpiece 11 can also be divided along the streets 13. As a result, a plurality of device chips each including the device 15 are manufactured.

[0052] When the workpiece 11 is subjected to ablation processing by irradiating the laser beam 48, the melt of the workpiece 11 scatters as debris (processing chips) 21. Also, in the processing chamber where the workpiece 11 is processed, a small amount of particles and mist may be floating. When such foreign matter adheres to the condenser lens 68, the laser beam 48 may not be irradiated onto the workpiece 11 under the intended conditions, and there is a risk of processing defects.

[0053] Therefore, in the present embodiment, a foreign matter adhesion prevention unit 70 is mounted on the laser irradiation unit 44. The foreign matter adhesion prevention unit 70 prevents foreign matter such as debris 21 from adhering to the condenser lens 68.

[0054] Specifically, the foreign matter adhesion prevention unit 70 includes a strip-shaped protective film 72. The protective film 72 is disposed between the holding surface 28a of the holding unit 28 and the condenser lens 68 in a state of being stretched along a plane (XY plane in FIG. 3) perpendicular to the traveling direction of the laser beam 48 (the optical axis direction of the optical system 64). Note that the width of the protective film 72 is larger than the diameter of the condenser lens 68. And the protective film 72 is positioned so as to overlap the entire condenser lens 68 and cover the lower surface side of the laser processing head 46.

[0055] The protective film 72 is transparent to the laser beam 48. That is, at least a part of the laser beam 48 incident on the protective film 72 passes through the protective film 72 and is irradiated onto the workpiece 11. The transmittance of the protective film 72 to the laser beam 48 is preferably 80% or more, and more preferably 90% or more.

[0056] The specific material, thickness, etc. of the protective film 72 can be appropriately selected according to the wavelength of the laser beam 48, etc. For example, when the workpiece 11 is subjected to ablation processing with a laser beam 48 having a wavelength of 355 nm, a polyolefin (PO)-based film, a polyester (PE)-based film, etc. can be used as the protective film 72.

[0057] The polyolefin-based film is a film made of a polymer synthesized using an alkene as a monomer. Examples of polyolefin-based films include polyethylene films, polypropylene films, polystyrene films, and the like. Further, a film made of a copolymer of propylene and ethylene or a film made of an olefin-based elastomer can also be used.

[0058] The polyester-based film is a film made of a polymer synthesized using a dicarboxylic acid (a compound having two carboxyl groups) and a diol (a compound having two hydroxyl groups) as monomers. Examples of polyester-based films include polyethylene terephthalate films, polyethylene naphthalate films, and the like. Further, a polytrimethylene terephthalate film, a polybutylene terephthalate film, or polybutylene naphthalate can also be used.

[0059] One end side (the right side of the paper surface in FIG. 3) of the protective film 72 is connected to a feeding unit (feeding mechanism) 74A that feeds out the protective film 72. Further, the other end side (the left side of the paper surface in FIG. 3) of the protective film 72 is connected to a winding unit (winding mechanism) 74B that winds up the protective film 72.

[0060] The feeding unit 74A includes a columnar first roller 76A and a first rotation driving source 78A such as a motor connected to the first roller 76A. For example, the first roller 76A is arranged such that its longitudinal direction (height direction) is along the Y-axis direction. Further, the first rotation driving source 78A rotates the first roller 76A around a rotation axis substantially parallel to the longitudinal direction of the first roller 76A.

[0061] One end portion of the protective film 72 is fixed to the first roller 76A, and the protective film 72 is wound around the first roller 76A. Then, when the first roller 76A is rotated by the first rotation driving source 78A, the protective film 72 wound around the first roller 76A is fed out from the first roller 76A.

[0062] Further, the delivery unit 74A includes a columnar first pulley 80A that supports the protective film 72 delivered from the first roller 76A. The first pulley 80A is arranged such that its longitudinal direction (height direction) is generally parallel to the longitudinal direction of the first roller 76A. Also, the first pulley 80A is held in a state where it can freely rotate around a rotation axis generally parallel to its longitudinal direction.

[0063] The winding unit 74B includes a columnar second roller 76B and a second rotation drive source 78B such as a motor connected to the second roller 76B. For example, the second roller 76B is arranged such that its longitudinal direction (height direction) is along the Y-axis direction. Also, the second rotation drive source 78B rotates the second roller 76B around a rotation axis generally parallel to the longitudinal direction of the second roller 76B.

[0064] The other end of the protective film 72 is fixed to the second roller 76B, and the protective film 72 is wound around the second roller 76B. Then, when the second rotation drive source 78B rotates the second roller 76B, the protective film 72 is wound around the second roller 76B.

[0065] Further, the winding unit 74B includes a columnar second pulley 80B that supports the protective film 72 wound around the second roller 76B. The second pulley 80B is arranged such that its longitudinal direction (height direction) is generally parallel to the longitudinal direction of the second roller 76B. Also, the second pulley 80B is held in a state where it can freely rotate around a rotation axis generally parallel to its longitudinal direction.

[0066] The first pulley 80A and the second pulley 80B are arranged at substantially the same height position (position in the Z-axis direction) so as to sandwich the traveling path of the laser beam 48 (optical axis of the optical system 64). And, the area of the protective film 72 that is not wound around the first roller 76A or the second roller 76B is wound around the first pulley 80A and the second pulley 80B. Thereby, the protective film 72 is supported by the first pulley 80A and the second pulley 80B in a stretched state between the first pulley 80A and the second pulley 80B so as to cover the lower surface side of the laser processing head 46.

[0067] The laser beam 48 that has passed through the condensing lens 68 passes through the protective film 72 and irradiates the workpiece 11. Thereby, laser processing is performed on the workpiece 11. Also, since the protective film 72 is provided so as to cover the lower surface side of the laser processing head 46, it is possible to prevent foreign matter existing below the laser processing head 46 from entering the inside of the laser processing head 46 and adhering to the condensing lens 68.

[0068] For example, when the workpiece 11 is processed with the laser beam 48, debris 21 that is the melt of the workpiece 11 scatters. And, the debris 21 scattered from the workpiece 11 toward the laser irradiation unit 44 side is received by the protective film 72 and does not adhere to the condensing lens 68.

[0069] However, if a large amount of debris 21 adheres to the area of the protective film 72 that overlaps with the condensing lens 68, the irradiation of the laser beam 48 to the workpiece 11 may be hindered. Therefore, the protective film 72 is periodically fed out from the feeding unit 74A and wound up by the winding unit 74B.

[0070] Specifically, the control unit 54 (see FIG. 1) outputs control signals to the first rotation drive source 78A and the second rotation drive source 78B, thereby rotating the first roller 76A and the second roller 76B a predetermined number of times at a predetermined timing. As a result, the area where the debris 21 of the protective film 72 adheres moves from the position overlapping the condenser lens 68, and the area where the debris 21 of the protective film 72 does not adhere is newly positioned in the area overlapping the condenser lens 68. Thereby, the protective film 72 covering the condenser lens 68 is in a state of being replaced.

[0071] There is no limitation on the timing for moving the protective film 72, and it can be appropriately set according to the amount of debris 21 generated, etc. For example, the protective film 72 may be moved each time a predetermined number of workpieces 11 (e.g., one piece) are processed, or the protective film 72 may be moved each time the workpiece 11 is processed along a predetermined number of streets 13 (see FIG. 2). Also, the protective film 72 can be moved while irradiating the workpiece 11 with the laser beam 48. In this case, the processing of the workpiece 11 and the replacement of the protective film 72 are performed simultaneously.

[0072] In addition, the protective film 72 also prevents the adhesion of foreign matter other than the debris 21 to the condenser lens 68. For example, in the processing chamber where the workpiece 11 is processed, a small amount of particles or mist may be floating. The intrusion of such foreign matter into the laser processing head 46 is also prevented by the protective film 72.

[0073] As described above, the laser irradiation unit 44 of the laser processing apparatus 2 according to the present embodiment is equipped with a foreign matter adhesion prevention unit 70 including a protective film 72 disposed between the holding surface 28a of the holding unit 28 and the condenser lens 68, a first roller 76A for feeding out the protective film 72, and a second roller 76B for winding up the protective film 72. Then, the protective film 72 prevents the adhesion of foreign matter to the condenser lens 68, and the protective film 72 can be easily moved by the first roller 76A and the second roller 76B.

[0074] By mounting the above-described foreign matter adhesion prevention unit 70 on the laser irradiation unit 44, it becomes possible to easily and quickly position the protective film 72 without foreign matter adhering thereto at a position overlapping the condenser lens 68. As a result, it is possible to avoid the processing of the workpiece 11 by the laser processing apparatus 2 being interrupted for a long time due to the foreign matter removal operation, and the operating efficiency of the laser processing apparatus 2 is improved.

[0075] Note that the protective film 72 may be in contact with the lower surface of the laser processing head 46, or may be held in a state separated from the lower surface of the laser processing head 46. When the protective film 72 is in contact with the lower surface of the laser processing head 46, it is possible to prevent foreign matter such as particles and mist existing above the protective film 72 from entering the inside of the laser processing head 46 through the gap between the laser processing head 46 and the protective film 72 and adhering to the condenser lens 68. On the other hand, when the protective film 72 is not in contact with the lower surface of the laser processing head 46, it is possible to prevent the protective film 72 from being damaged by the friction acting between the laser processing head 46 and the protective film 72.

[0076] Also, in FIG. 3, the case where the condenser lens 68 of the laser irradiation unit 44 is disposed above the holding surface 28a of the holding unit 28 has been described, but the condenser lens 68 may be disposed below the holding surface of the holding unit. In this case, the protective film 72 is also disposed below the holding surface of the holding unit.

[0077] FIG. 4 is a partial cross-sectional front view showing the holding unit (conveying unit) 90 and the laser irradiation unit 44. The laser processing apparatus 2 (see FIG. 1) may include a holding unit 90 that holds and conveys the workpiece 11 instead of or in addition to the holding unit 28.

[0078] The holding unit 90 includes a columnar support shaft 92 and a disc-shaped holding portion 94 fixed to the tip (lower end) of the support shaft 92. The lower surface of the holding portion 94 is a flat surface generally parallel to the horizontal direction (XY plane direction), and constitutes a holding surface 94a for holding the workpiece 11. The holding surface 94a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), etc. formed inside the holding portion 94.

[0079] For example, first, the holding unit 90 is arranged such that the holding surface 94a contacts the back surface 11b side (tape 19 side) of the workpiece 11. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 94a, the workpiece 11 or the frame 17 is suction-held by the holding portion 94 via the tape 19.

[0080] The laser irradiation unit 44 is installed below the holding unit 90. Then, the laser processing head 46 and the optical system 64 are arranged such that the upper surface side of the condenser lens 68 faces the holding surface 94a of the holding unit 90. Also, the protective film 72 is arranged to cover the upper surface side of the laser processing head 46. As shown in FIG. 4, the traveling path (optical axis of the optical system 64) of the laser beam 48 may be inclined with respect to the direction perpendicular to the holding surface 94a. In this case, the protective film 72 arranged between the holding surface 94a and the condenser lens 68 is also stretched to be inclined with respect to the holding surface 94a.

[0081] The holding unit 90 holds the workpiece 11 and positions it above the laser processing head 46. Then, the workpiece 11 is laser-processed on the surface 11a side by irradiating the lower surface side (surface 11a side) of the workpiece 11 with the laser beam 48 from the laser irradiation unit 44. At this time, the debris 21 generated in the region of the workpiece 11 irradiated with the laser beam 48 falls toward the laser processing head 46 side. However, since the debris 21 is received by the protective film 72, it does not adhere to the condenser lens 68.

[0082] As described above, when the condenser lens 68 is disposed below the holding surface 94a, debris 21 is likely to fall and scatter toward the condenser lens 68. However, since the condenser lens 68 is covered with the protective film 72, adhesion of the debris 21 to the condenser lens 68 is prevented. Then, by moving the protective film 72 by the feeding unit 74A and the winding unit 74B, the protective film 72 without the debris 21 adhering thereto can be easily and quickly positioned on the traveling path of the laser beam 48.

[0083] In addition, the structure, method, etc. according to the above embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention.

Explanation of Reference Numerals

[0084] 11 Workpiece 11a Surface 11b Back surface 13 Street (division planned line) 15 Device 17 Frame 17a Opening 19 Tape 21 Debris (processing chips) 2 Laser processing apparatus 4 Base 6 Moving mechanism (moving unit) 8 Y-axis moving mechanism (Y-axis moving unit) 10 Y-axis guide rail 12 Y-axis moving table 14 Y-axis ball screw 16 Y-axis pulse motor 18 X-axis moving mechanism (X-axis moving unit) 20 X-axis guide rail 22 X-axis moving table 24 X-axis ball screw 26 X-axis pulse motor 28 Holding unit (holding table, chuck table) 28a Holding surface 30 Clamp 32 Z-axis moving mechanism (Z-axis moving unit) 34 Support structure 34a Base 34b Support part 36 Z-axis guide rail 38 Z-axis moving plate 40 Z-axis pulse motor 42 Support member 44 Laser irradiation unit 46 Laser processing head 48 Laser beam 50 Imaging unit 52 Display unit (display part, display device) 54 Control unit (control part, control device) 60 Laser oscillator 62 Regulator 64 Optical system 66 Mirror 68 Condensing lens 70 Foreign object adhesion prevention unit 72 Protective film 74A Feeding unit (feeding mechanism) 74B Winding unit (winding mechanism) 76A First roller 76B Second roller 78A First rotation drive source 78B Second rotation drive source 80A First pulley 80B Second pulley 90 Holding unit (conveying unit) 92 Support shaft 94 Holding part 94a Holding surface

Claims

1. A laser processing apparatus for processing a workpiece by irradiating the workpiece with a laser beam, comprising: a holding unit including a holding surface for holding the workpiece; a laser irradiation unit configured to irradiate the laser beam onto the workpiece held by the holding unit; wherein the laser irradiation unit includes: a laser oscillator; a condenser lens configured to condense the laser beam emitted from the laser oscillator; a foreign matter adhesion prevention unit configured to prevent adhesion of foreign matter to the condenser lens; wherein the foreign matter adhesion prevention unit includes: a protective film disposed between the holding surface and the condenser lens and having transparency to the laser beam; a first roller having one end of the protective film fixed thereto and configured to feed out the protective film by rotation; a rotatable first pulley configured to support the protective film fed out from the first roller; a second roller having the other end of the protective film fixed thereto and configured to wind up the protective film by rotation; a rotatable second pulley configured to support the protective film wound up by the second roller; the condenser lens is disposed below the holding surface; and a traveling path of the laser beam irradiated onto the workpiece is inclined with respect to the vertical direction. A laser processing apparatus characterized by this.

2. The laser processing apparatus according to claim 1, wherein the protective film is a polyolefin-based film or a polyester-based film.

3. The laser processing apparatus according to claim 1 or 2, wherein the foreign matter adhesion prevention unit further includes a first rotation drive source configured to rotate the first roller and a second rotation drive source configured to rotate the second roller. ​ ​

Images