Laser processing equipment

Abstract

[Problem] To provide a laser processing apparatus with high operating efficiency. [Solution] A laser processing apparatus that processes a workpiece by irradiation with a laser beam, comprising: a holding unit including a holding surface for holding the workpiece; and a laser irradiation unit that irradiates the workpiece held by the holding unit with a laser beam, wherein the laser irradiation unit comprises: a laser oscillator; a condenser lens that focuses the laser beam emitted from the laser oscillator; and a foreign matter adhesion prevention unit that prevents foreign matter from adhering to the condenser lens, wherein the foreign matter adhesion prevention unit comprises: a protective film disposed between the holding surface and the condenser lens and having permeability to the laser beam; a first roller that fixes one end of the protective film and feeds the protective film out by rotation; and a second roller that fixes the other end of the protective film and winds up the protective film by rotation.

Description

Technical Field

[0001] This invention relates to a laser processing apparatus for processing a workpiece by means of laser beam irradiation. Prior Technology

[0002] In the manufacturing process of electronic components, a wafer containing components is formed in multiple regions divided by multiple dicing lines (pre-defined dicing lines) arranged in a grid pattern. By dicing this wafer along the dicing lines, multiple component chips, each containing a component, are obtained. These component chips are then assembled into various electronic devices such as mobile phones and personal computers.

[0003] In wafer dicing, a dicing device is used to cut the workpiece using a ring-shaped dicing blade. On the other hand, in recent years, there has also been development of processes for dicing wafers using laser processing equipment. The laser processing equipment includes a holding unit (chuck) 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 a laser beam is irradiated towards the wafer from the laser irradiation unit, thereby performing laser processing on the wafer.

[0004] For example, Patent Document 1 discloses a processing method in which laser processing grooves are formed on a wafer along the dicing track by irradiation with a laser beam. If an external force is applied to the wafer with the laser processing grooves formed along the dicing track, the laser processing grooves function as the starting point for dicing, and the wafer is diced along the dicing track. [Known Technical Documents] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2006-319198 Summary of the Invention

[0006] [The problem that the invention aims to solve] The laser irradiation unit, which is mounted on a laser processing apparatus, has a focusing lens that focuses the laser beam at a predetermined position. Furthermore, when processing a workpiece with the laser processing apparatus, the focusing lens is positioned so as to face the workpiece, for example, to irradiate the laser beam by focusing the light on the surface or interior of the workpiece.

[0007] For example, if a workpiece is ablated using a laser beam, the molten material will break down into fragments (processing chips) and scatter. Furthermore, small amounts of particles or mist may sometimes float in the processing chamber. If such foreign matter adheres to the condenser lens, the laser beam will not irradiate the workpiece as intended, raising concerns about poor processing. Therefore, when foreign matter adheres to the condenser lens, it will be cleaned or replaced.

[0008] However, when cleaning or replacing the condenser lens, it is essential to handle it carefully to avoid damaging its characteristics. Furthermore, when installing the condenser lens into the laser irradiation unit, its position and orientation must be precisely adjusted to focus the laser beam at the desired location. Therefore, the time-consuming installation and removal of the condenser lens contributes to a decrease in the operating efficiency of the laser processing equipment.

[0009] In addition, laser irradiation units are sometimes equipped with a cover that covers the side of the condenser lens facing the workpiece. The cover is made of glass or similar material that allows the laser beam to pass through, allowing the laser beam from the condenser lens to irradiate the workpiece. This cover prevents foreign objects from adhering to the condenser lens, reducing the frequency of cleaning or replacing the condenser lens.

[0010] When a predetermined amount of foreign matter adheres to the cover, although the cover can be cleaned or replaced in a manner that does not adversely affect laser processing, the cover is cheaper and easier to install and remove than the condenser lens, so cleaning or replacing the cover does not require excessive effort or cost. However, as long as the cover is cleaned or replaced regularly, it is unavoidable to interrupt the processing of the workpiece by the laser processing equipment, and the operating efficiency of the laser processing equipment will be limited.

[0011] The present invention was made in view of this problem, and its purpose is to provide a laser processing apparatus with high operating efficiency.

[0012] [Technical means to solve the problem] According to one aspect of the present invention, a laser processing apparatus is provided, which processes a workpiece by irradiation with a laser beam, and comprises: a holding unit including a holding surface for holding the workpiece; and a laser irradiation unit for irradiating the workpiece held by the holding unit with the laser beam, the laser irradiation unit comprising: a laser oscillator; a condenser lens for focusing 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 comprising: a protective film disposed between the holding surface and the condenser lens and having permeability to the laser beam; a first roller for fixing one end of the protective film and feeding the protective film out by rotation; and a second roller for fixing the other end of the protective film and winding the protective film by rotation.

[0013] Furthermore, the focusing lens can be positioned below the retaining surface. Also, the protective film can be a polyolefin-based film or a polyester-based film.

[0014] [Invention Benefits] In a laser processing unit of a laser processing apparatus according to the present invention, a foreign matter adhesion prevention unit is provided. The foreign matter adhesion prevention unit includes: a protective film disposed between the holding surface of a holding unit and a condenser lens; a first roller for dispensing the protective film; and a second roller for winding up the protective film. Furthermore, the protective film can prevent foreign matter from adhering to the condenser lens, and the protective film can be easily moved by the first and second rollers.

[0015] By assembling the aforementioned foreign matter adhesion prevention unit into the laser irradiation unit, the protective film free of foreign matter can be easily and quickly positioned to overlap with the condenser lens. As a result, the processing of workpieces by the laser processing unit can be prevented from being interrupted for a long time due to foreign matter removal operations, thereby improving the operating efficiency of the laser processing unit. Simple Explanation of the Diagram

[0016] Figure 1 is a perspective view of a laser processing apparatus. Figure 2 is a three-dimensional view of the workpiece. Figure 3 is a partial cross-sectional front view of the holding unit (holding platform) and the laser irradiation unit. Figure 4 is a partial cross-sectional front view of the holding unit (transfer unit) and the laser irradiation unit. Implementation

[0017] Hereinafter, with reference to the accompanying drawings, one embodiment of the present invention will be described. First, an example of the configuration of the laser processing apparatus according to this embodiment will be described. FIG1 is a perspective view of the laser processing apparatus 2. In FIG1, the X-axis direction (processing feed direction, first horizontal direction) and the Y-axis direction (indexing feed direction, second horizontal direction) are mutually perpendicular. Furthermore, the Z-axis direction (height direction, vertical direction, up-down direction) is perpendicular to both the X-axis and Y-axis directions.

[0018] The laser processing apparatus 2 includes a base 4, which supports the various components constituting the laser processing apparatus 2. The upper surface of the base 4 is a flat surface that is substantially 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 unit 8 includes a pair of Y-axis guide rails 10, which are arranged along the Y-axis direction on the upper surface of the base 4. A flat Y-axis moving stage 12 is slidably mounted on the pair of Y-axis guide rails 10.

[0020] A nut (not shown) is provided on the back (lower surface) side of the Y-axis moving stage 12. A Y-axis ball screw 14 is screwed into this nut, and the Y-axis ball screw 14 is arranged between a pair of Y-axis guide rails 10 along the Y-axis direction. Furthermore, a Y-axis pulse motor 16 is connected to the end of the Y-axis ball screw 14 to rotate it. If the Y-axis ball screw 14 is rotated by the Y-axis pulse motor 16, the Y-axis moving stage 12 will move along the Y-axis guide rails 10 in the Y-axis direction.

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

[0022] A nut (not shown) is provided on the back (lower surface) side of the X-axis moving platform 22. An X-axis ball screw 24 is screwed into this nut, and the X-axis ball screw 24 is arranged between a pair of X-axis guide rails 20 along the X-axis direction. Furthermore, an X-axis pulse motor 26 is connected to the end of the X-axis ball screw 24 to rotate it. If the X-axis ball screw 24 is rotated by the X-axis pulse motor 26, the X-axis moving stage 22 will move along the X-axis guide rails 20 in the X-axis direction.

[0023] A holding unit (holding table, chuck table) 28 is provided on the front (upper surface) of the X-axis moving stage 22 to hold the workpiece 11 (see Figure 2), which is the object to be processed by the laser processing device 2. Furthermore, a plurality of clamps 30 are provided around the holding unit 28, which grip and fix the annular frame 17 (see Figure 2) supporting the workpiece 11.

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

[0025] If the Y-axis moving stage 12 is moved along the Y-axis direction, the holding unit 28 will move along the Y-axis direction. Furthermore, if the X-axis moving stage 22 is moved along the X-axis direction, the holding unit 28 will move along the X-axis direction. Additionally, the holding unit 28 is connected to a rotational drive source (not shown), such as a motor, that rotates the holding unit 28 about a rotational axis approximately parallel to the Z-axis direction.

[0026] A Z-axis moving mechanism 32 is provided at the rear end of the base 4 (behind the Y-axis moving unit 8, the X-axis moving mechanism 18, and the holding unit 28). The Z-axis moving mechanism 32 has a support structure 34 disposed on the upper surface of the base 4. The support structure 34 includes: a cuboid base 34a, which is fixed to the base 4; and a columnar support portion 34b, which protrudes upward from the end of the base 34a. The front (side) side of the support portion 34b is formed as a plane along the Z-axis direction.

[0027] A pair of Z-axis guide rails 36 are provided on the front side of the support 34b along the Z-axis direction. The flat Z-axis moving stage 38 is mounted on the pair of Z-axis guide rails 36 in a state that allows it to slide along the Z-axis guide rails 36.

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

[0029] Support member 42 supports laser irradiation unit 44. Laser irradiation unit 44 has laser processing head 46, and irradiates laser beam 48 from laser processing head 46 toward workpiece 11 held by holding unit 28 (see FIG. 2). In this way, laser processing is performed on workpiece 11.

[0030] Furthermore, a camera unit 50 is installed in the laser irradiation unit 44 to capture images of the workpiece 11 held by the holding unit 28. The camera unit 50 includes a visible light camera and an infrared camera; the visible light camera has an image sensor that receives visible light and converts it into an electrical signal, and the infrared camera has an image sensor that receives infrared light and converts it into an electrical signal. The images obtained by capturing images of the workpiece 11 using the camera unit 50 are used for alignment between the holding unit 28 and the laser processing head 46.

[0031] If the Z-axis moving stage 38 is moved along the Z-axis direction, the laser processing head 46 and the camera unit 50 will move (rise and fall) along the Z-axis direction. This allows for adjustment of the focusing position of the laser beam 48 and focusing of the camera unit 50.

[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 moves the holding unit 28, the laser beam 48 irradiated from the laser processing head 46 and the camera unit 50 relative to each other along the processing feed direction (X-axis direction) and the indexing feed direction (Y-axis direction).

[0033] Furthermore, the laser processing apparatus 2 is equipped with a display unit (display section, display device) 52 for displaying various information about 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 into the laser processing apparatus 2 by touching the touch panel. That is, the touch panel also functions as an input unit (input section, input device) for inputting various information into the laser processing apparatus 2, and is used as a user interface. However, the input unit may also be a mouse, keyboard, etc., set up separately from the display unit 52.

[0035] Furthermore, the laser processing apparatus 2 includes a control unit (control section, control device) 54 for controlling the laser processing apparatus 2. The control unit 54 is connected to each component constituting the laser processing apparatus 2 (moving mechanism 6, holding unit 28, fixture 30, laser irradiation unit 42, camera unit 50, display unit 52, etc.). The control unit 54 operates the laser processing apparatus 2 by outputting control signals to each component of the laser processing apparatus 2.

[0036] For example, the control unit 54 is constructed using a computer. Specifically, the control unit 54 includes: an arithmetic unit that performs various calculations required for the operation of the laser processing apparatus 2; and a memory unit that stores various information (data, programs, etc.) used for the operation of the laser processing apparatus 2. The arithmetic unit is composed of a processor such as a CPU (Central Processing Unit). Furthermore, the memory unit is composed of memory such as ROM (Read Only Memory) and RAM (Random Access Memory).

[0037] The workpiece 11 is laser-processed using the laser processing apparatus 2. Figure 2 is a perspective view of the workpiece 11. For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as monocrystalline silicon, and has a front side 11a and a back side 11b that are substantially parallel to each other. The workpiece 11 is divided into multiple rectangular regions by multiple dicing lines (predetermined dividing lines) 13 arranged in a grid pattern in an intersecting manner.

[0038] On the front side 11a of the multiple regions divided by the dicing channel 13, components 15, such as IC (Integrated Circuit), LSI (Large Scale Integration), LED (Light Emitting Diode), and MEMS (Micro Electro Mechanical Systems), are formed respectively. By dividing the workpiece 11 along the dicing channel 13, multiple component chips, each equipped with a component 15, are obtained.

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

[0040] When processing the workpiece 11 using the laser processing apparatus 2, a ring-shaped frame 17 is used to support the workpiece 11 to facilitate its operation (transfer, holding, etc.). The frame 17 is made of a metal such as SUS (stainless steel), and a circular opening 17a is provided in the center of the frame 17, extending through the frame 17 in the thickness direction. Furthermore, the diameter of the opening 17a is larger than the diameter of the workpiece 11.

[0041] A circular adhesive film 19 is attached to the workpiece 11 and the frame 17. For example, the adhesive film 19 comprises a circular, thin-film substrate and an adhesive layer (paste layer) disposed on the substrate. The substrate is made of resins such as polyolefin, polyvinyl chloride, and polyethylene terephthalate. Furthermore, the adhesive layer is made of epoxy, acrylic, or rubber-based adhesives. Additionally, the adhesive layer may also use a UV-curing resin that hardens upon exposure to ultraviolet light.

[0042] With the workpiece 11 positioned inside the opening 17a of the frame 17, if the central portion of the adhesive film 19 is attached to the back side 11b of the workpiece 11 and the outer periphery of the adhesive film 19 is attached to the frame 17, the workpiece 11 is supported by the frame 17 through the adhesive film 19.

[0043] Next, the laser irradiation unit 44 assembled in the laser processing apparatus 2 will be described. Figure 3 is a partial cross-sectional front view of the holding unit 28 and the laser irradiation unit 44.

[0044] When the workpiece 11 is processed by the laser processing apparatus 2, the workpiece 11 is held by the holding unit 28. For example, when laser processing is applied to the front 11a side of the workpiece 11, the workpiece 11 is positioned on the holding unit 28 with the front 11a side exposed above and the back 11b side (the adhesive film 19 side) facing the holding surface 28a. Furthermore, the frame 17 is fixed by a plurality of clamps 30 (see FIG. 1). If the attractive force (negative pressure) of the suction source is applied to the holding surface 28a in this state, the workpiece 11 will be attracted and held by the holding unit 28 through the adhesive film 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, which adjusts the power of the laser beam 48 emitted from the laser oscillator 60. Furthermore, the laser irradiation unit 44 includes an optical system 64 that guides the laser beam 48 toward the workpiece 11 held by the holding unit 28. The optical system 64 comprises multiple optical elements and controls the direction and shape of the laser beam 48.

[0046] Specifically, the optical system 64 includes a mirror 66 that reflects the laser beam 48 and a focusing lens 68 that focuses the laser beam 48. The focusing lens 68 is held inside the laser processing head 46, with its lower surface facing the holding surface 28a of the holding unit 28.

[0047] The laser beam 48, emitted from the laser oscillator 60 and whose power has been adjusted by the adjuster 62, is reflected by the mirror 66 and enters the focusing lens 68, where it is focused at a predetermined position. For example, the laser beam 48 is focused on the front side 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 laser processing performed on the workpiece 11. For example, in the case of performing an ablation process on the workpiece 11, the wavelength of the laser beam 48 is set such that at least a portion of the laser beam 48 is absorbed by the workpiece 11. That is, a laser beam that is absorbent to the workpiece 11 is used as the laser beam 48. Furthermore, other irradiation conditions of the laser beam 48 (average output, repetition frequency, processing feed rate, etc.) are also appropriately set in a manner suitable for performing an ablation process on the workpiece 11.

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

[0050] If the laser beam 48 is focused on the front surface 11a or inside the workpiece 11 while the holding unit 28 is moved along the processing feed direction (X-axis direction), the holding unit 28 and the laser beam 48 will move relative to each other, and the laser beam 48 will scan along the processing direction. As a result, an ablation process is performed on the workpiece 11, forming a linear laser processing groove on the front surface 11a side of the workpiece 11.

[0051] For example, the workpiece 11 is divided along the cutting path 13 by forming a laser processing groove from the front side 11a to the back side 11b along the entire cutting path 13 (see FIG. 2). Furthermore, after forming a laser processing groove with a depth less than the thickness of the workpiece 11 along the entire cutting path 13 on the front side 11a of the workpiece 11, the back side 11b of the workpiece 11 is ground with a grinding stone, exposing the laser processing groove on the back side 11b of the workpiece 11. This also allows for the division of the workpiece 11 along the cutting path 13. As a result, multiple component wafers, each equipped with a component 15, are manufactured.

[0052] Furthermore, if the workpiece 11 is subjected to ablation processing by irradiation with laser beam 48, the molten material of the workpiece 11 will turn into debris (processing chips) 21 and scatter. Also, in the processing chamber where the workpiece 11 is processed, small amounts of particles or mist may sometimes float. If such foreign matter adheres to the focusing lens 68, the laser beam 48 will not irradiate the workpiece 11 under the expected conditions, raising concerns about poor processing.

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

[0054] Specifically, the foreign matter adhesion prevention unit 70 includes a strip-shaped protective film 72. The protective film 72 is positioned between the holding surface 28a of the holding unit 28 and the condenser lens 68, extending along a plane perpendicular to the travel direction of the laser beam 48 (the optical axis direction of the optical system 64) (in the XY plane of FIG. 3). Furthermore, the width of the protective film 72 is greater than the diameter of the condenser lens 68. The protective film 72 is then positioned such that it completely overlaps with the condenser lens 68 and covers the lower surface of the laser processing head 46.

[0055] The protective film 72 is permeable to the laser beam 48. That is, at least a portion of the laser beam 48 that has entered the protective film 72 will penetrate the protective film 72 and irradiate 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 and thickness of the protective film 72 can be appropriately selected according to the wavelength of the laser beam 48. For example, in the case where the workpiece 11 is subjected to ablation processing with a laser beam 48 with a wavelength of 355nm, a polyolefin (PO) film, a polyester (PE) film, or the like can be used as the protective film 72.

[0057] Polyolefin films are films made of polymers synthesized using olefins as monomers. Examples of polyolefin films include polyethylene films, polypropylene films, and polystyrene films. Furthermore, films made of copolymers of propylene and ethylene, or films made of olefin-based elastomers, can also be used.

[0058] Polyester films are films composed of polymers synthesized using dicarboxylic acids (compounds having two carboxyl groups) and diols (compounds having two hydroxyl groups) as monomers. Examples of polyester films include polyethylene terephthalate (PET) films and polyethylene naphthalate (PAN) films. Furthermore, polyethylene terephthalate (PTA) films, polybutylene terephthalate (PET) films, or polybutylene naphthalate (PAN) films can also be used.

[0059] One end of the protective film 72 (on the right side of the paper in Figure 3) is connected to a delivery unit (delivery mechanism) 74A for delivering the protective film 72. The other end of the protective film 72 (on the left side of the paper in Figure 3) is connected to a winding unit (winding mechanism) 74B for winding up the protective film 72.

[0060] The delivery unit 74A includes a cylindrical first roller 76A and a first rotation drive source 78A, such as a motor, connected to the first roller 76A. For example, the first roller 76A is arranged such that its length direction (height direction) is along the Y-axis direction. Furthermore, the first rotation drive source 78A rotates the first roller 76A about a rotation axis that is substantially parallel to the length direction of the first roller 76A.

[0061] The first roller 76A fixes one end of the protective film 72 and winds the protective film 72. Then, if the first roller 76A is rotated by the first rotation drive source 78A, the protective film 72 wound on the first roller 76A will be fed out from the first roller 76A.

[0062] Furthermore, the delivery unit 74A includes a cylindrical first pulley 80A, which supports the protective film 72 that has been delivered from the first roller 76A. The first pulley 80A is configured such that its length direction (height direction) is substantially parallel to the length direction of the first roller 76A. Moreover, the first pulley 80A is held in a state where it can freely rotate about a rotation axis substantially parallel to its length direction.

[0063] The take-up unit 74B includes a cylindrical 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 length direction (height direction) is along the Y-axis. Furthermore, the second rotation drive source 78B rotates the second roller 76B about a rotation axis that is substantially parallel to the length direction of the second roller 76B.

[0064] The second roller 76B holds the other end of the protective film 72 and winds the protective film 72. Then, if the second roller 76B is rotated by the second rotation drive source 78B, the protective film 72 is wound onto the second roller 76B.

[0065] Furthermore, the take-up unit 74B includes a cylindrical second pulley 80B, which supports the protective film 72 wound onto the second roller 76B. The second pulley 80B is arranged such that its length direction (height direction) is substantially parallel to the length direction of the second roller 76B. Moreover, the second pulley 80B is held in a state where it can freely rotate about a rotation axis substantially parallel to its length direction.

[0066] The first pulley 80A and the second pulley 80B are positioned at approximately the same height (in the Z-axis direction) to clamp the travel path of the laser beam 48 (optical axis of the optical system 64). Furthermore, the area of ​​the protective film 72 not wound around the first roller 76A or the second roller 76B is wound around the first pulley 80A and the second pulley 80B. Thus, the protective film 72, while extended between the first pulley 80A and the second pulley 80B, is supported by the first pulley 80A and the second pulley 80B in a manner that covers the lower surface of the laser processing head 46.

[0067] The laser beam 48, which has passed through the condenser lens 68, penetrates the protective film 72 and irradiates the workpiece 11. This allows the workpiece 11 to undergo laser processing. Furthermore, by providing the protective film 72 to cover the lower surface of the laser processing head 46, foreign objects present on the lower surface of the laser processing head 46 are prevented from entering the interior of the laser processing head 46 and adhering to the condenser lens 68.

[0068] For example, if the workpiece 11 is processed with the laser beam 48, the molten material of the workpiece 11, i.e. the fragments 21, will scatter. Then, the fragments 21 that scatter from the workpiece 11 to the side of the laser irradiation unit 44 will be received by the protective film 72 and will not adhere to the focusing lens 68.

[0069] However, if a large number of fragments 21 adhere to the area where they overlap with the focusing lens 68 of the protective film 72, they may sometimes obstruct the laser beam 48 from irradiating the workpiece 11. Therefore, the protective film 72 is periodically fed out from the delivery unit 74A and wound up by the take-up unit 74B.

[0070] Specifically, the control unit 54 (see Figure 1) outputs control signals to the first rotation drive source 78A and the second rotation drive source 78B, causing the first roller 76A and the second roller 76B to rotate a predetermined number of times at predetermined time points. As a result, the area of ​​the protective film 72 with attached debris 21 moves from its position overlapping with the condenser lens 68, while the area of ​​the protective film 72 without attached debris 21 is repositioned to overlap with the condenser lens 68. This achieves a state where the protective film 72 covering the condenser lens 68 has been replaced.

[0071] There is no limitation on the timing of moving the protective film 72; it can be appropriately set according to the amount of fragments 21 generated. For example, the protective film 72 can be moved whenever a predetermined number of pieces (e.g., one piece) of workpiece 11 are processed, or whenever the workpiece 11 is processed along a predetermined number of cutting paths 13 (see Figure 2). Furthermore, the protective film 72 can also be moved while the laser beam 48 is irradiating the workpiece 11. In this case, the processing of the workpiece 11 and the replacement of the protective film 72 are performed simultaneously.

[0072] Furthermore, the protective film 72 also prevents foreign objects other than fragment 21 from adhering to the condenser lens 68. For example, in the processing chamber where the workpiece 11 is processed, there may sometimes be trace amounts of particles or mist floating in the air. The protective film 72 can also prevent such foreign objects from intruding into the laser processing head 46.

[0073] As described above, in this embodiment, the laser irradiation unit 44 of the laser processing apparatus 2 is equipped with a foreign matter adhesion prevention unit 70. The foreign matter adhesion prevention unit 70 includes: a protective film 72 disposed between the holding surface 28a of the holding unit 28 and the condenser lens 68; a first roller 76A that delivers the protective film 72; and a second roller 76B that winds up the protective film 72. Furthermore, the protective film 72 prevents foreign matter from adhering 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 assembling the aforementioned foreign matter adhesion prevention unit 70 into the laser irradiation unit 44, the protective film 72 without foreign matter adhesion can be easily and quickly positioned to overlap with the condenser lens 68. As a result, the processing of the workpiece 11 performed by the laser processing apparatus 2 can be prevented from being interrupted for a long time due to foreign matter removal operations, thereby improving the operating efficiency of the laser processing apparatus 2.

[0075] Furthermore, the protective film 72 can contact the lower surface of the laser processing head 46, or it can be held in a state where it is separated from the lower surface of the laser processing head 46. If the protective film 72 contacts the lower surface of the laser processing head 46, it can prevent foreign objects such as particles and mist present on the upper side of the protective film 72 from entering the interior 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 does not contact the lower surface of the laser processing head 46, it can prevent the protective film 72 from being damaged due to friction between the laser processing head 46 and the protective film 72.

[0076] Furthermore, although Figure 3 describes the case where the condenser lens 68 of the laser irradiation unit 44 is positioned above the holding surface 28a of the holding unit 28, the condenser lens 68 can also be positioned below the holding surface of the holding unit. In this case, the protective film 72 is also positioned below the holding surface of the holding unit.

[0077] Figure 4 is a partial cross-sectional front view of the holding unit (transfer unit) 90 and the laser irradiation unit 44. The laser processing apparatus 2 (see Figure 1) may also have a holding unit 90 for holding and transferring the workpiece 11 in place of the holding unit 28, or may have both the holding unit 90 and the holding unit 28.

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

[0079] For example, the holding unit 90 is initially configured such that the holding surface 94a contacts the back side 11b (the adhesive film 19 side) of the workpiece 11. In this state, if the attractive force (negative pressure) of the attraction source is applied to the holding surface 94a, the workpiece 11 or the frame 17 is attracted and held by the holding part 94 through the adhesive film 19.

[0080] The laser irradiation unit 44 is disposed below the holding unit 90. Furthermore, the laser processing head 46 and the optical system 64 are arranged such that the upper surface of the condenser lens 68 faces the holding surface 94a of the holding unit 90. The protective film 72 is disposed to cover the upper surface of the laser processing head 46. Moreover, as shown in FIG4, the travel path of the laser beam 48 (the optical axis of the optical system 64) can also be tilted relative to the direction perpendicular to the holding surface 94a. In this case, the protective film 72 disposed between the holding surface 94a and the condenser lens 68 also extends in a manner tilted relative to the holding surface 94a.

[0081] The holding unit 90 holds the workpiece 11 and positions it above the laser processing head 46. Furthermore, laser processing is performed on the front surface 11a side of the workpiece 11 by irradiating the lower surface side (front 11a side) of the workpiece 11 with a laser beam 48 from the laser irradiation unit 44. At this time, fragments 21 generated in the area of ​​the workpiece 11 irradiated by the laser beam 48 fall off the laser processing head 46 side. However, since the fragments 21 are not received by the protective film 72, they do not adhere to the condenser lens 68.

[0082] As described above, when the condenser lens 68 is positioned below the holding surface 94a, the fragments 21 may fall and easily scatter on the side of the condenser lens 68. However, since the condenser lens 68 is covered by the protective film 72, the fragments 21 are prevented from adhering to the condenser lens 68. Moreover, by moving the protective film 72 through the delivery unit 74A and the take-up unit 74B, the protective film 72 without attached fragments 21 can be easily and quickly positioned in the travel path of the laser beam 48.

[0083] Furthermore, the structure and method of the above-described embodiments can be appropriately modified and implemented without departing from the purpose of the present invention.

[0084] 11: Workpiece 11a: Front 11b: Back 13: Cutting track (pre-defined dividing line) 15: Components 17: Framework 17a: Opening 19: Adhesive film 21: Fragments (processing chips) 2: Laser processing equipment 4:Abutment 6: Moving mechanism (moving unit) 8: Y-axis moving mechanism (Y-axis moving unit) 10: Y-axis guide rail 12: Y-axis moving stage 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 stage 24: X-axis ball screw 26: X-axis pulse motor 28: Holding Unit (Holding Stage, Chuck Stage) 28a: Maintain surface 30: Fixture 32: Z-axis moving mechanism (Z-axis moving unit) 34: Support Structure 34a: Base 34b: Support section 36: Z-axis guide rail 38: Z-axis moving stage 40: Z-axis pulse motor 42: Supporting components 44: Laser Irradiation Unit 46: Laser processing head 48: Laser Beam 50: Camera Unit 52: Display unit (display section, display device) 54: Control unit (control section, 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: Delivery Unit (Delivery Mechanism) 74B: Rewind Unit (Rewind Mechanism) 76A: First Roller 76B: Second Roller 78A: First Rotational Drive Source 78B: Second Rotary Drive Source 80A: First pulley 80B: Second pulley 90: Holding Unit (Transfer Unit) 92: Support shaft 94: Maintaining Section 94a: Maintain surface

Claims

1. A laser processing apparatus for processing a workpiece by irradiation with a laser beam, characterized in that it comprises: a holding unit including a holding surface for holding the workpiece; and a laser irradiation unit for irradiating the workpiece held by the holding unit with the laser beam, the laser irradiation unit comprising: a laser oscillator; a condenser lens for focusing 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 comprising: a protective film disposed between the holding surface and the condenser lens, and having permeability to the laser beam; a first roller for fixing one end of the protective film and feeding the protective film out by rotation; and a first pulley rotatable for supporting the protective film fed out from the first roller. The second roller, which fixes the other end of the protective film and winds up the protective film by rotation; and the second pulley, which is rotatable and supports the protective film wound on the second roller; the condenser lens is disposed below the holding surface; and the path of the laser beam irradiating the workpiece is inclined relative to the vertical direction.

2. The laser processing apparatus as described in claim 1, wherein, The protective film is a polyolefin-based film or a polyester-based film.

3. The laser processing apparatus as described in claim 1 or 2, wherein, The foreign object adhesion prevention unit further comprises: a first rotation drive source that rotates the first roller; and a second rotation drive source that rotates the second roller.

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