Optical processing apparatus, optical system, and laser processing method

Abstract

To provide a processor and an optical system capable of suitably adjusting an optical path length while suppressing the fluctuation of the center of gravity accompanying the movement of a movable optical component.SOLUTION: The laser processing apparatus includes a laser oscillator that emits a laser beam, an irradiation unit that irradiates an object to be processed with the laser beam emitted from the laser oscillator, an irradiation unit moving mechanism that moves the irradiation unit, a plurality of optical elements that are disposed on an optical path of the laser beam emitted from the laser oscillator and guide the laser beam from the laser oscillator to the irradiation unit, and an adjustment moving mechanism that moves the optical elements in a moving direction of the irradiation unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical processing apparatus that irradiates a workpiece such as a semiconductor wafer with a laser beam, and an optical system that guides light emitted from a light source to the object to be irradiated. [Background technology]

[0002] Device chips such as integrated circuits (ICs) are essential components for electronic devices such as mobile phones and personal computers. In the device chip manufacturing process, a plurality of streets (planned division lines) are set in a grid pattern on the surface of a wafer, and devices are formed in each of the multiple regions defined by these streets. The wafer is then divided along the streets to obtain individual device chips.

[0003] Wafers are divided using cutting equipment that uses an annular cutting blade to cut the wafer, but in recent years, the technology of dividing wafers using laser processing has also been put to practical use. A laser beam emitted from an oscillator is guided to the wafer, which is the workpiece, using various optical elements (mirrors, condenser lenses, etc.), and the wafer is processed by forming grooves or cutting.

[0004] Prior art documents describing such laser processing techniques include, for example, Patent Documents 1 and 2.

[0005] Patent Document 1 proposes an optical processing device that scans a processing area by moving a nozzle head while irradiating the processing area with light such as a laser beam from the nozzle head.

[0006] Here, when performing laser processing, it is important from the viewpoint of processing stability that the spot diameter and irradiation position of the irradiated laser beam be as constant as possible on the workpiece to be irradiated with the laser beam. On the other hand, in an apparatus in which the position of the laser beam irradiation part (nozzle head) moves, such as the optical processing apparatus described in Patent Document 1, the movement may cause the distance (optical path length) of the laser beam path from the light source to the irradiation object to fluctuate.

[0007] If the laser beam is not a precisely collimated beam, if there is an optical element that converges or diverges the laser beam along the optical path, or if the laser beam branches along the optical path, fluctuations in the optical path length can lead to fluctuations in the irradiation state on the irradiation target (such as an increase in the spot diameter or a fluctuation in the focal position).

[0008] Therefore, in the technology described in Patent Document 2, in an optical system equipped with movable optical components in the optical path from the light-emitting unit to the light-receiving unit, an additional mirror is provided in the optical path, and the optical path length is kept constant by moving the mirror in accordance with the movement of the movable optical component.

[0009] That is, in the technology described in Patent Document 2, for example, in the optical system shown in Figure 1 of Patent Document 2, when the objective lens, which is a movable optical component, moves to the right (in the direction in which the optical path length becomes shorter), the mirror is moved to the right (away from the light source) accordingly, thereby lengthening the optical path length before and after the mirror, thereby offsetting the fluctuation in the optical path length. Conversely, when the objective lens moves to the left (in the direction in which the optical path length becomes longer), the mirror is moved to the left (toward the light source) accordingly, thereby shortening the optical path length before and after the mirror.

[0010] However, with this method, the direction in which the movable optical component moves is the same as the direction in which the mirror moves to suppress fluctuations in the optical path length, which creates the problem that these movements cause the center of gravity of the processing device to fluctuate significantly. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2017 / 175839 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-99667 Summary of the Invention [Problem to be solved by the invention]

[0012] An object of the present invention is to provide a processing device and an optical system that can suitably adjust the optical path length while suppressing fluctuations in the center of gravity as movable optical components move. [Means for solving the problem]

[0013] According to one aspect of the present invention, there is provided an optical processing device comprising: a laser oscillator that emits a laser beam; an irradiation unit that irradiates a workpiece with the laser beam emitted from the laser oscillator; an irradiation section movement mechanism that moves the irradiation unit; a plurality of optical elements that are arranged on the optical path of the laser beam emitted from the laser oscillator and that guide the laser beam from the laser oscillator to the irradiation unit; and an adjustment movement mechanism that moves the optical elements in the movement direction of the irradiation unit, and that is configured so that the optical path length of the laser beam can be adjusted by moving the optical elements with the adjustment movement mechanism in the opposite direction to the irradiation unit in the movement direction of the irradiation unit as the irradiation unit moves.

[0014] Preferably, the plurality of optical elements are arranged in the optical path of the laser beam so that two or more turning portions are formed in the optical path of the laser beam in the direction of movement of the irradiation unit, and among the optical elements, the optical elements that form the even-numbered turning portions counting from the irradiation unit along the optical path of the laser beam are configured to be movable by the adjustment movement mechanism.

[0015] According to another aspect of the present invention, there is provided an optical system that has a plurality of optical elements on an optical path and guides light to an irradiated portion, the optical system comprising: a movable optical component that is arranged on the optical path and moves to vary the optical path, and an adjustment movement mechanism that moves the optical element in the movement direction of the movable optical component, and is configured so that the optical path length of the laser beam can be adjusted by moving the optical element with the adjustment movement mechanism in the opposite direction to the movable optical component in the movement direction of the movable optical component as the movable optical component moves.

[0016] Preferably, the plurality of optical elements are arranged so as to form two or more turning portions in the optical path in the direction of movement of the movable optical component, and the optical elements that form the even-numbered turning portions counting from the movable optical component along the optical path are configured to be movable by the adjustment movement mechanism.

[0017] Preferably, the direction of incidence of light along the optical path onto the movable optical component is parallel to the direction of movement of the movable optical component, and the plurality of optical elements include at least first to fourth reflective optical elements upstream of the movable optical component, wherein light is incident on the first reflective optical element in the same direction as the direction of incidence of light onto the movable optical component, with respect to the direction of movement of the movable optical component; at the first reflective optical element, the light is reflected in a direction intersecting the direction of movement of the movable optical component and incident on the second reflective optical element; at the second reflective optical element, the light is reflected in a direction opposite to the direction of incidence of light onto the movable optical component, with respect to the direction of movement of the movable optical component, and incident on the third reflective optical element; and at the third reflective optical element, the light is reflected in a direction intersecting the direction of movement of the movable optical component and incident on the fourth reflective optical element. [Effects of the Invention]

[0018] According to an optical processing device and an optical system according to one aspect of the present invention, when the optical element is moved in accordance with the movement of the movable optical component (illumination unit) to adjust the optical path length, the direction of movement of the optical element can be reversed relative to the direction of movement of the movable optical component, thereby making it possible to suitably adjust the optical path length while suppressing fluctuations in the center of gravity. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing an example (first embodiment) of an optical processing device. [Figure 2] FIG. 2 is a perspective view showing an example of the shape of the object to be processed. [Figure 3] FIG. 3 is a conceptual diagram that schematically shows the arrangement of the optical system in the optical processing device of the first embodiment. [Figure 4] FIG. 4 is a conceptual diagram that schematically shows another example (second embodiment) of the arrangement of the optical system in the optical processing device. [Figure 5] FIG. 5 is a conceptual diagram that schematically shows yet another example (third embodiment) of the arrangement of optical systems in an optical processing device. [Figure 6] FIG. 6 is a conceptual diagram that schematically shows yet another example (fourth embodiment) of the arrangement of optical systems in an optical processing device. [Figure 7] FIG. 7 is a perspective view showing still another example (fifth embodiment) of the configuration of the optical processing device. [Figure 8] FIG. 8 is a conceptual diagram showing a schematic arrangement of the optical system in the optical processing device of the fifth embodiment, as viewed from the Y direction. [Figure 9] FIG. 9 is a conceptual diagram showing a schematic arrangement of the optical system in the optical processing device of the fifth embodiment, as viewed from the X direction. DETAILED DESCRIPTION OF THE INVENTION

[0020] Embodiments of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view schematically showing the configuration of an optical processing device according to a first embodiment of the present invention. Here, a laser processing device 2 is shown as the optical processing device. Note that the optical processing device is not limited to a laser processing device, and various devices equipped with an optical system that directs light emitted from a light source to an irradiation target using various optical elements (mirrors, condenser lenses, etc.) can be envisioned.

[0021] In Fig. 1, the X, Y, and Z directions indicate the directions of three axes that are perpendicular to each other in three-dimensional space. The X direction (left-right direction) and the Y direction (front-back direction) are horizontal directions that are perpendicular to each other. The Z direction (up-down direction) is a vertical direction that is perpendicular to the X and Y directions. In the laser processing device 2 of the first embodiment, the direction along the X direction is the processing feed direction, and the direction along the Y direction is the indexing feed direction.

[0022] In this specification, expressions such as "along the X direction" and "along the XY plane" are used, but these do not necessarily mean that the orientation of a member or surface strictly coincides with or is parallel to these axes or planes. For example, they may be at a slight angle to each other but generally face in the same direction, or the angle or movement of a member may include a component in that direction.

[0023] The laser processing device 2 includes a workpiece holding mechanism 6 that supports and moves the workpiece 4 , and an irradiation mechanism 10 that includes an optical system that irradiates the workpiece 4 with a laser beam 8 .

[0024] The workpiece holding mechanism 6 includes a Y-axis movement mechanism 14 provided on the upper surface of the base 12, and a chuck table 16 attached to the Y-axis movement mechanism 14 as a holding portion.

[0025] Base 12 is a pedestal that forms the base of workpiece holding mechanism 6. The upper surface of base 12 forms a flat surface along the horizontal plane (XY plane), and Y-axis movement mechanism 14 is provided on this surface.

[0026] The Y-axis movement mechanism 14 is provided with a pair of Y-axis guide rails 14a extending parallel to each other along the Y direction on the upper surface of the base 12. A Y-axis movement table 14b, which forms a surface along a horizontal plane (XY plane), is mounted on the upper part of the pair of Y-axis guide rails 14a so as to be slidable along the longitudinal direction of the Y-axis guide rails 14a.

[0027] A Y-axis ball screw 14c is disposed between the pair of Y-axis guide rails 14a along the longitudinal direction of the Y-axis guide rails 14a. A nut portion (not shown) is provided on the rear surface (lower surface) side of the Y-axis moving table 14b. The Y-axis ball screw 14c passes through the nut portion.

[0028] A Y-axis pulse motor 14d for rotating the Y-axis ball screw 14c is connected to one longitudinal end of the Y-axis ball screw 14c. When the Y-axis pulse motor 14d is driven, the Y-axis ball screw 14c rotates about its own axis, and the Y-axis moving table 14b moves in the Y direction on the Y-axis guide rails 14a.

[0029] A chuck table 16 serving as a holding unit for holding the workpiece 4 is attached to the upper surface of the Y-axis moving table 14b. The upper surface of the chuck table 16 is flat along a horizontal plane (XY plane). The upper surface of the chuck table 16 is connected to a suction source (not shown) such as an ejector via a flow path (not shown) formed inside the chuck table 16 and a valve (not shown). Operation of the suction source generates negative pressure on the upper surface of the chuck table 16, allowing an article such as the workpiece 4 held on the upper surface to be sucked in. In other words, the upper surface of the chuck table 16 forms a holding surface 16a for holding the workpiece 4.

[0030] 2 is a perspective view showing an example of the shape of the workpiece 4. The workpiece 4 is a disk-shaped wafer made of a semiconductor material such as single crystal silicon. A plurality of streets (planned division lines) arranged in a grid pattern are set on the workpiece 4, thereby dividing the workpiece 4 into a plurality of rectangular regions. Devices such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices are formed on the surface of each region divided by the streets.

[0031] However, there are no limitations on the type, material, shape, structure, size, etc. of the workpiece 4. For example, the workpiece 4 may be a substrate (wafer) made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. Furthermore, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of devices formed on the workpiece 4, and the workpiece 4 does not necessarily have to have any devices formed thereon.

[0032] When the workpiece 4 is handled in an apparatus such as the laser processing apparatus 2 shown in Fig. 1, the workpiece 4 is handled in the form of a frame unit held by a frame 4a as shown in Fig. 2 for ease of handling, such as transport and holding. The frame 4a is a plate-shaped component made of metal such as SUS (stainless steel), and an opening is provided in the center of the frame 4a, penetrating the frame 4a in the thickness direction. The diameter of the opening is set larger than the diameter of the workpiece 4.

[0033] The workpiece 4 is supported on the frame 4a via an adhesive sheet 4b. The adhesive sheet 4b is composed of, for example, a circular film-like substrate with a diameter larger than the central opening of the frame 4a and an adhesive layer provided on the substrate. The substrate is formed from a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made from an epoxy-based, acrylic-based, or rubber-based adhesive, and this material is applied to at least one side of the substrate to form the adhesive layer. UV-curable resin can also be used as the material for the adhesive layer.

[0034] With the workpiece 4 placed inside the opening of the frame 4a, the central portion of the adhesive sheet 4b is attached to the workpiece 4 and the outer periphery of the adhesive sheet 4b is attached to the frame 4a, thereby supporting the workpiece 4 by the frame 4a.

[0035] As shown in FIG. 1, the irradiation mechanism 10 includes a laser oscillator 18 as a light source device, and an optical system 20 that guides the laser beam 8 emitted as collimated light from the laser oscillator 18 to the area (irradiated portion) where the workpiece 4 is located.

[0036] The laser oscillator 18 is a device that generates and emits a laser beam by oscillating a laser such as a YAG laser, a YVO4 laser, or a YLF laser. The emitted laser beam 8 is guided by an optical system 20 to an irradiation portion where the workpiece 4 is located, and is irradiated onto the workpiece 4. The optical system 20 is configured to include a plurality of optical elements provided on the optical path of the laser beam 8, and these optical elements control the traveling direction, shape, focusing position, etc. of the laser beam 8.

[0037] The following describes the configuration of the optical system 20. The optical system 20 in the first embodiment includes, as optical elements, a plurality of mirrors 22A, 22B, 22C, 22D, and 22E that reflect the laser beam 8 emitted from the laser oscillator 18, and a condenser lens 24 that condenses the laser beam 8 reflected by the mirrors 22A to 22E and irradiates the workpiece 4 with the laser beam 8.

[0038] The mirrors 22A to 22E are reflective optical elements. For example, dielectric multilayer mirrors can be used as the mirrors 22A to 22E, and a convex lens can be used as the condenser lens 24. The laser beam 8 emitted from the laser oscillator 18 is reflected by the mirrors 22A, 22B, 22C, and 22D in this order, and is guided to the irradiation unit 26.

[0039] Irradiation unit 26 incorporates mirror 22E and condenser lens 24. Laser beam 8 incident on irradiation unit 26 is reflected by mirror 22E and enters condenser lens 24. Laser beam 8 incident on condenser lens 24 is refracted by condenser lens 24 and is condensed at a target position (for example, the surface or inside of workpiece 4).

[0040] However, there is no limitation on the type of optical elements that make up the optical system 20, and any appropriate optical elements can be used as long as they can properly guide the laser beam 8 to the irradiated area. For example, the optical system 20 may include optical elements such as mirrors or lenses other than those listed above, or a polarizing beam splitter (PBS), a diffractive optical element (DOE), or an LCOS-SLM (Liquid Crystal On Silicon - Spatial Light Modulator).

[0041] In the first embodiment, of the optical elements constituting the optical system 20, the condenser lens 24 and the mirror 22E located immediately before it (upstream with respect to the optical path of the laser beam 8) are configured as part of an irradiation unit 26 that irradiates the workpiece 4 with the laser beam 8, and the irradiation unit 26 is configured to be movable along the X direction. The movement direction of the irradiation unit 26 and the incident direction of the laser beam 8 from the mirror 22E to the irradiation unit 26 are parallel to each other.

[0042] Hereinafter, a component of the optical system 20 that is configured to be movable, such as the irradiation unit 26, that is provided on the optical path and moves to vary the optical path, will be referred to as a movable optical component as necessary. Also, a mechanism that moves the irradiation unit 26 as a movable optical component will be referred to as an irradiation unit moving mechanism 28.

[0043] In addition, in the first embodiment, among the optical elements, mirrors 22A and 22B located on the most upstream side with respect to the optical path of laser beam 8 are also configured to be movable in the X direction to adjust the optical path length. The mechanism for moving the optical elements in this way to adjust the optical path length is referred to as adjustment movement mechanism 30.

[0044] The components constituting the optical system 20 (mirrors 22A to 22E, condenser lens 24, and irradiation unit 26) are supported by a support mechanism 32. The support mechanism 32 shown in Fig. 1 is configured to arrange the mirrors 22A to 22E, condenser lens 24, and irradiation unit 26 along the XZ plane by a support frame 34 that forms a support surface 34a along the XZ plane.

[0045] The irradiation unit movement mechanism 28 is provided with a pair of X-axis guide rails 28a extending parallel to each other along the X direction on the support surface 34a of the support frame 34. An X-axis movement table 28b, which forms a surface along a vertical plane (XZ plane) perpendicular to the Y direction, is attached to the pair of X-axis guide rails 28a so as to be slidable along the longitudinal direction of the X-axis guide rails 28a.

[0046] An X-axis ball screw 28c is disposed between the pair of X-axis guide rails 28a along the longitudinal direction of the X-axis guide rails 28a. A nut portion (not shown) is provided on the back surface of the X-axis moving table 28b (the surface facing the support surface 34a of the support frame 34), and the X-axis ball screw 28c passes through the nut portion.

[0047] An X-axis pulse motor 28d for rotating the X-axis ball screw 28c is connected to one end in the longitudinal direction of the X-axis ball screw 28c. When the X-axis pulse motor 28d is driven, the X-axis ball screw 28c rotates about the axis of the X-axis ball screw 28c, and the X-axis moving table 28b moves along the longitudinal direction (direction along the X direction) of the X-axis guide rail 28a.

[0048] An irradiation unit 26 is attached to the X-axis moving table 28b. The irradiation unit 26 incorporates a mirror 22E and a condenser lens 24, and the lower part of the irradiation unit 26 is configured as an irradiation head 26a that emits a laser beam 8.

[0049] 1, in the optical system 20 of the first embodiment, a laser beam 8 is incident on a mirror 22E in an irradiation unit 26 along the X direction and is reflected downward (along the Z direction) by the mirror 22E. A condenser lens 24 is disposed below the mirror 22E, and the laser beam 8 reflected downward by the mirror 22E passes through the condenser lens 24, is refracted, and further passes through the irradiation head 26a to be irradiated onto the workpiece 4 below.

[0050] The adjustment movement mechanism 30 can be configured as a mechanism generally similar to the irradiation unit movement mechanism 28, for example, as described below.

[0051] The adjustment movement mechanism 30 has a pair of X-axis guide rails 30a extending parallel to each other along the X direction on the support surface 34a of the support frame 34, and an X-axis movement table 30b having a surface along the XZ plane is slidably mounted on the pair of X-axis guide rails 30a.

[0052] An X-axis ball screw 30c is disposed between the pair of X-axis guide rails 30a and along the longitudinal direction of the X-axis guide rails 30a. The X-axis ball screw 30c passes through a nut (not shown) provided on the back side of the X-axis moving table 30b. An X-axis pulse motor 30d is connected to one end of the X-axis ball screw 30c, and operation of the X-axis pulse motor 30d moves the X-axis moving table 30b in the X direction.

[0053] Mirrors 22A and 22B are attached to the top and bottom of the X-axis moving table 30b of the adjustment movement mechanism 30, and the laser beam 8 is reflected by these mirrors, so that the direction of the laser beam 8 can be changed.

[0054] It should be noted that a mechanism for moving the irradiation unit 26 and the chuck table 16 in the vertical direction (Z direction) may be provided, but a detailed description thereof will be omitted here.

[0055] Furthermore, the laser processing apparatus 2 is equipped with a controller 36 that monitors and controls the operation of each component of the laser processing apparatus 2. The controller 36 is connected to the workpiece holding mechanism 6 and the irradiation mechanism 10, and inputs control signals to these mechanisms. In response to this, the controller 36 operates each component, such as the Y-axis pulse motor 14d of the movement mechanism 14, the chuck table 16, the laser oscillator 18 of the irradiation mechanism 10, the irradiation unit movement mechanism 28, and the X-axis pulse motors 28d and 30d of the adjustment movement mechanism 30.

[0056] The controller 36 is configured by, for example, a computer. Specifically, the controller 36 includes a calculation unit that executes processes such as calculations required for the operation of each unit, and a storage unit that stores various information (data, programs, etc.). The processing unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

[0057] The controller 36 is connected to a display unit 36a that displays various information related to the operation of the laser processing device 2, and an input unit 36b for inputting operations for each unit.

[0058] The display unit 36a and the input unit 36b are, for example, touch panel displays. In this case, the display unit 36a displays, for example, an operation screen for inputting various information, commands, etc. to the laser processing device 2, and the operator can input information to the controller 36 by touching the operation screen. In other words, the touch panel display can be configured as a device that combines the functions of the display unit 36a and the input unit 36b. The display unit 36a and the input unit 36b can be configured as separate devices, for example, the display unit 36a can be a liquid crystal display, and the input unit 36b can be an input device such as a mouse or keyboard that is provided separately from the liquid crystal display.

[0059] The arrangement of the optical elements in the optical system 20 will be described with reference to Fig. 3. Fig. 3 is a conceptual diagram that schematically shows the arrangement of the optical system in the optical processing device of the first embodiment.

[0060] In the optical system 20 of the first embodiment, the optical path of the laser beam 8 from the laser oscillator 18, which is a light source device, to the workpiece 4 in the irradiated portion is set along the XZ plane, and the laser beam 8 emitted from the laser oscillator 18 along the X direction is reflected in order by mirrors 22A to 22E and is irradiated downward (along the Z direction) from the irradiation head 26a of the irradiation unit 26 located at the most downstream portion of the optical path.

[0061] That is, four reflective optical elements (mirrors 22A, 22B, 22C, 22D) are provided upstream of the mirror 22E and the focusing lens 24, which constitute part of the irradiation unit 26 configured as a movable optical component, in terms of the optical path of the laser beam 8.

[0062] It should be noted that an attenuator or the like for adjusting the light intensity of the laser beam 8 may be provided on the optical path, but is not shown here.

[0063] In the first embodiment, each of the mirrors 22A to 22E is disposed at an angle of 45 degrees with respect to the direction of incidence of the laser beam 8. The mirror 22A reflects the laser beam 8 emitted from the laser oscillator 18 in the horizontal direction (X direction) downward (along the Z direction). The mirror 22B is disposed below the mirror 22A, and reflects the laser beam 8 reflected downward from the mirror 22A in a direction along the X direction.

[0064] The direction in which the laser beam 8 is reflected by the mirror 22B is opposite to the direction in which the laser beam 8 is emitted from the laser oscillator 18. In this way, the direction of the laser beam 8 is reflected by the mirrors 22A and 22B.

[0065] Mirror 22C reflects laser beam 8 reflected horizontally (X direction) from mirror 22B downward (along the Z direction). Mirror 22D is disposed below mirror 22C and reflects laser beam 8 reflected downward from mirror 22C in a direction along the X direction.

[0066] The direction in which the laser beam 8 is reflected by the mirror 22D is opposite to the direction in which the laser beam 8 is reflected by the mirror 22B. In this way, the direction of the laser beam 8 is turned back again by the mirrors 22C and 22D.

[0067] The laser beam 8 reflected in the X direction by the mirror 22D is reflected by a mirror 22E provided in the irradiation unit 26, passes through a condenser lens 24 below it, and is irradiated onto the workpiece 4 from the irradiation head 26a.

[0068] As described above, in the optical processing device (laser processing device) 2 and the optical system 20 of the first embodiment, the laser beam 8 is incident on the first mirror 22A in the same direction (rightward) as the incident direction of the laser beam 8 on the irradiation unit 26 with respect to the moving direction (X direction) of the irradiation unit 26, and the laser beam 8 is reflected by the first mirror 22A in a direction (downward) intersecting the moving direction of the irradiation unit 26 and incident on the second mirror 22B, and the laser beam 8 is reflected by the second mirror 22B in a direction (downward) intersecting the moving direction of the irradiation unit 26. With respect to the movement direction (X direction) of the irradiation unit 26, the laser beam 8 is reflected in a direction opposite to the incident direction of the irradiation unit 26 (leftward) and is incident on the third mirror 22C, and the laser beam 8 is reflected from the third mirror 22C in a direction intersecting the movement direction of the irradiation unit 26 (downward) and is incident on the fourth mirror 22D, and the laser beam 8 is incident on the irradiation unit 26 from the fourth mirror 22D in a direction parallel to the movement direction (X direction) of the irradiation unit 26.

[0069] Note that "the same direction / opposite direction as the incident direction of the laser beam 8 to the irradiation unit 26, with respect to the moving direction (X direction) of the irradiation unit 26" here does not mean that the direction of the laser beam 8 is exactly parallel to the X direction (left-right direction), but refers to which way in the X direction the X component of the direction of the laser beam 8 faces (whether it faces left or right) in the X direction. In other words, "the same direction as the incident direction of the laser beam 8 to the irradiation unit 26, with respect to the moving direction (X direction) of the irradiation unit 26" includes a direction that exactly matches the direction when the incident direction of the laser beam 8 to the irradiation unit 26 is rightward along the X direction, for example, and also includes a direction that is tilted at an angle of less than 90° in the Y direction or Z direction.

[0070] When the workpiece 4 is irradiated with the laser beam 8, the irradiation conditions are set appropriately depending on the type of workpiece 4 and the content of the laser processing to be performed on the workpiece 4.

[0071] For example, when dividing the workpiece 4, which is a wafer made of single crystal silicon, the irradiation conditions of the laser beam 8 are set so that the area of ​​the workpiece 4 irradiated with the laser beam 8 is modified by multiphoton absorption. Other irradiation conditions are also set so that the workpiece 4 is appropriately modified.

[0072] While irradiating the laser beam 8 and focusing it inside the workpiece 4, the irradiation unit movement mechanism 28 (see FIG. 1) is operated to move the irradiation unit 26 in the processing feed direction (direction along the X direction). The laser beam 8 irradiated from the irradiation unit 26 moves along the processing feed direction toward the workpiece 4 held on the chuck table 16. Inside the workpiece 4, the material of the workpiece 4 is modified by multiphoton absorption, and a modified layer is formed along the streets.

[0073] After irradiation of the laser beam 8 along one street is completed, the movement mechanism 14 of the workpiece holding mechanism 6 is operated to move the chuck table 16 in the index feed direction (along the Y direction) by a distance corresponding to the distance between the streets. Thereafter, laser processing is performed along the processing feed direction in the same manner as above. By repeating the same procedure, the laser beam 8 is irradiated onto the workpiece 4 along multiple streets.

[0074] Furthermore, the chuck table 16 is rotated 90 degrees around an axis along the Z direction, and the same procedure as above is repeated, thereby forming a plurality of modified layers in a lattice pattern along the streets inside the workpiece 4.

[0075] The region of the workpiece 4 where the modified layer is formed becomes more fragile than the other regions, so when an external force is applied to the workpiece 4, the workpiece 4 is split along the streets starting from the modified layer. In other words, the modified layer functions as the starting point for splitting the workpiece 4.

[0076] There is no limitation on the type of laser processing. For example, the workpiece 4 may be subjected to ablation processing using a laser beam 8 having a wavelength that is absorbed by the material of the workpiece 4. In this case, the ablation processing forms grooves along the streets that extend from the front surface to the back surface of the workpiece 4, thereby dividing the workpiece 4.

[0077] In the laser processing step described above, irradiation unit 26 as a movable optical component is moved in the X direction by irradiation unit movement mechanism 28, and accordingly, the distance from mirror 22D to mirror 22E, one of the optical elements constituting optical system 20, varies. In optical processing device (laser processing device) 2 and optical system 20 of the first embodiment, adjustment movement mechanism 30 is operated accordingly to move other optical elements (mirrors 22A, 22B), thereby absorbing the variation in the distance between mirrors 22D, 22E and suppressing variation in the optical path length from laser oscillator 18 to workpiece 4.

[0078] 3, for example, when the movable optical component (irradiation unit) 26 moves to the left, the optical path from mirror 22D to mirror 22E is lengthened. Therefore, if mirrors 22A and 22B are moved to the right by adjustment movement mechanism 30 (see FIG. 1) in conjunction with the movement of irradiation unit 26, the optical path from laser oscillator 18 to mirror 22C is shortened, thereby suppressing fluctuations in the overall optical path length. In this case, if the amount of movement of irradiation unit 26 in the X direction by irradiation unit movement mechanism 28 is d, then it is sufficient to move mirrors 22A and 22B by d / 2 in the X direction opposite to irradiation unit 26 by adjustment movement mechanism 30.

[0079] Conversely, when the irradiation unit 26 moves to the right by the movement amount d, the mirrors 22A and 22B are moved to the left by d / 2.

[0080] The adjustment of the optical path by the movement of the mirrors 22A and 22B in accordance with the movement of the irradiation unit 26 is controlled by the controller 36, for example, in accordance with a program stored in the storage unit of the controller 36.

[0081] When processing the workpiece 4 using the laser beam 8 as described above, if the laser beam 8 is not an accurate collimated light, if an optical element (such as a condenser lens 24) that converges or diffuses the laser beam is present along the optical path, or if the laser beam branches along the optical path (not shown), fluctuations in the optical path length may lead to fluctuations in the irradiation state on the workpiece 4 (such as an increase in the spot diameter or a fluctuation in the focal position).

[0082] Therefore, in the optical processing device (laser processing device) 2 and optical system 20 of this first embodiment, an adjustment movement mechanism 30 is provided that moves some of the optical elements (mirrors 22A, 22B) that make up the optical system 20, and by moving the mirrors 22A, 22B in conjunction with the movement of the movable optical component 26, changes in the optical path length are suppressed.

[0083] A similar mechanism for adjusting the optical path length has already been proposed, for example, as described in Patent Document 2. However, in the technique described in Patent Document 2, the direction of movement of the optical element for adjusting the optical path length must be the same as the direction of movement of the movable optical component. That is, for example, when the objective lens, which is a movable optical component, moves to the right, the mirror is moved to the right to adjust the optical path length, and when the objective lens moves to the left, the mirror is moved to the left.

[0084] When an optical element is moved in accordance with the movement of a movable optical component, the center of gravity fluctuates significantly due to the movement of these components in the same direction. If the position of the center of gravity shifts significantly within the optical system or device, tilt or vibration may occur, so it is desirable to minimize the movement of the center of gravity.

[0085] In the laser processing apparatus 2 and optical system 20 of this first embodiment, similar to the technology described in Patent Document 2, the optical path length is adjusted by moving other optical elements (mirrors 22A, 22B) in accordance with the movement of the irradiation unit 26, which is a movable optical component, during laser processing, but in this case, fluctuations in the center of gravity are suppressed by reversing the direction of movement of both.

[0086] The adjustment of the optical path length by such movement is made possible by the fact that the optical path of the laser beam 8 is turned back at least twice by the optical elements in the movement direction (direction along the X direction) of the irradiation unit 26 configured as a movable optical component, and that the optical elements constituting the even-numbered turning portions, when counted along the optical path from the irradiation unit 26, move in the movement direction (direction along the X direction) of the optical component (irradiation unit) 26.

[0087] 3, the laser beam 8 emitted from the laser oscillator 18 is reflected a total of five times by mirrors 22A to 22E and its direction is changed. With respect to the movement direction of the irradiation unit 26 (the direction along the X direction), after being emitted from the laser oscillator 18, the laser beam 8 is first reflected once by mirrors 22A and 22B and then reflected again by mirrors 22C and 22D.

[0088] When tracing the optical path upstream from the irradiation unit 26, which is a movable optical component, mirrors 22C and 22D form the first turning portion of the optical path (indicated by reference symbol T1 in FIG. 3), and mirrors 22A and 22B form the second turning portion (indicated by reference symbol T2) as seen from the irradiation unit 26. By making the mirrors 22A and 22B that form this second turning portion movable along the X direction by the adjustment movement mechanism 30, fluctuations in the optical path length caused by movement of the irradiation unit 26 along the X direction can be offset by movement of the optical elements (mirrors 22A and 22B) in the direction opposite to the movement of the irradiation unit 26 in the X direction.

[0089] If a similar adjustment movement mechanism were provided for mirrors 22C and 22D that constitute the first turning point T1 as seen from irradiation unit 26, and this were to be used to offset the fluctuation in optical path length due to the movement of irradiation unit 26, it would be necessary to move mirrors 22C and 22D in the same direction in the X direction as the movement of irradiation unit 26, and the movement of irradiation unit 26 and mirrors 22C and 22D would result in significant fluctuation in the center of gravity.

[0090] In this way, when trying to suppress fluctuations in the center of gravity, adjustment of the optical path length using the adjustment movement mechanism needs to be performed on the optical elements that make up the even-numbered turning points, rather than the odd-numbered turning points counting along the optical path from the movable optical component.

[0091] Fig. 4 is a conceptual diagram showing a schematic diagram of another example (second embodiment) of the arrangement of the optical system in the optical processing device. The basic configuration is similar to that of the first embodiment shown in Fig. 3, except that a polarizing beam splitter 40 is provided as an optical element in the middle of the optical path.

[0092] The mechanism comprising this polarizing beam splitter 40 and mirrors 22F and 22G placed nearby is equivalent to the mechanism comprising the polarizing beam splitter and first and second mirrors shown in FIG. 1 of Patent Document 2.

[0093] In the optical system 38 of the second embodiment shown in Fig. 4 of the present application, a polarizing beam splitter 40 is disposed on the optical path between the laser oscillator 18 and the mirror 22F. A wave plate 40a that converts the polarization state of the laser beam 8 is provided on the part of the polarizing beam splitter 40 facing the mirror 22F side.

[0094] The wave plate 40a converts, for example, the laser beam 8 emitted as linearly polarized light from the laser oscillator 18 into circularly polarized light. The circularly polarized laser beam 8 is reflected by mirrors 22F and 22G and returns to the polarizing beam splitter 40. Of the laser beam 8 that has returned to the polarizing beam splitter 40, the component with the rotation direction reversed is converted into linearly polarized light whose polarization direction is rotated 90 degrees from the state when it was emitted from the laser oscillator 18.

[0095] With this mechanism, the polarized beam splitter 40 transmits the laser beam 8 incident from the laser oscillator 18 as is, while the laser beam 8 incident from the mirrors 22F and 22G side after passing through the wave plate 40a is reflected downward.

[0096] The laser beam 8 reflected downward from the polarizing beam splitter 40 is reflected in the X direction by a mirror 22B provided below the polarizing beam splitter 40. The configuration of the optical system 38 below the mirror 22B (mirrors 22B to 22E, the condenser lens 24, and the irradiation unit 26) is the same as that of the first embodiment described in FIG.

[0097] Thus, in the optical system 38 of the second embodiment shown in FIG. 4, the first folded portion of the optical path of the laser beam 8 as seen from the irradiation unit 26, which is a movable optical component, is formed by the mirrors 22C and 22D, and the second folded portion T2 is formed by the mirrors 22B, 22F, and 22G and the polarizing beam splitter 40.

[0098] In such an optical system 38, if a mechanism similar to the above-mentioned adjustment movement mechanism 30 (see FIG. 1) is provided on the mirrors 22F and 22G that form the second folded portion T2 and configured to be movable in the X direction, the optical path length can be adjusted while suppressing fluctuations in the center of gravity through a movement similar to that in the first embodiment.

[0099] In the second embodiment, when adjusting the optical path length by moving the optical elements, the polarizing beam splitter 40 and the mirror 22B may be moved in addition to the mirrors 22F and 22G.

[0100] Alternatively, the optical path length can be similarly adjusted by moving mirror 22G in a direction connecting the upper left and lower right in Fig. 4. In this case, the movement direction of mirror 22G, which is an optical element that constitutes turning portion T2 of the optical path, is largely inclined with respect to the X direction, but the movement direction also includes a component in the X direction, so it is possible to suppress fluctuations in the center of gravity that accompany movement of irradiation unit 26 in the X direction and adjustment of the optical path length.

[0101] Fig. 5 is a conceptual diagram showing a schematic diagram of yet another example (third embodiment) of the arrangement of the optical system in the optical processing device. In the first embodiment of Fig. 3, mirrors 22A-22D as optical elements form two return portions T1 and T2 in the X direction on the optical path of the laser beam 8, but in the third embodiment shown in Fig. 5, four more mirrors 22H-22K are provided in the optical system 42, thereby forming four return portions T1-T4 on the optical path.

[0102] The four mirrors 22H to 22K are located upstream of the mirrors 22A to 22E (between the laser oscillator 18 and the mirror 22A in terms of the optical path). The arrangement of the mirrors 22A to 22E is substantially the same as the arrangement of the mirrors 22A to 22E in the first embodiment shown in Fig. 3. The arrangement of the mirrors 22H to 22K on the upstream side thereof is similar to the arrangement of the mirrors 22A to 22D.

[0103] In the optical system 42 of the third embodiment, the laser beam 8 emitted to the left along the X direction from the laser oscillator 18 located at the upper right in FIG. 5 is first reflected downward by the mirror 22H, then reflected to the right by the mirror 22I, then reflected downward by the mirror 22J, and then reflected to the left by the mirror 22K.

[0104] The laser beam 8 reflected to the left from mirror 22K enters mirror 22A, is reflected downward by mirror 22A, then reflected to the right by mirror 22B, then reflected downward by mirror 22C, then reflected to the left by mirror 22D, reflected by mirror 22E built into irradiation unit 26, passes through condenser lens 24, and is irradiated onto the workpiece 4 below from irradiation head 26a.

[0105] In such an optical system 42, as viewed from the irradiation unit 26, which is a movable optical component, the first folded portion T1 in the X direction of the optical path is formed by mirrors 22C and 22D, the second folded portion T2 is formed by mirrors 22A and 22B, the third folded portion T3 is formed by mirrors 22J and 22K, and the fourth folded portion T4 is formed by mirrors 22H and 22I.

[0106] Of these, mirrors 22A, 22B and mirrors 22H, 22I that form even-numbered turning portions T2, T4 are configured to be movable along the X direction by a mechanism similar to the above-mentioned adjustment movement mechanism 30 (see FIG. 1).

[0107] With this mechanism, too, by using the same movement as in the first and second embodiments, it is possible to adjust the optical path length while suppressing fluctuations in the center of gravity as irradiation unit 26 moves along the X direction. However, in the case of the third embodiment, if mirrors 22A, 22B and mirrors 22H, 22I that form turning portions T2, T4 are moved simultaneously, then the movement amount of mirrors 22A, 22B and mirrors 22H, 22I in the X direction will be d / 4 on the opposite side to the movement of irradiation unit 26.

[0108] 6 is a conceptual diagram showing a schematic diagram of yet another example (fourth embodiment) of the arrangement of the optical system in the optical processing device. In the first and third embodiments shown in FIGS. 3 and 5, mirrors 22A-22D and mirrors 22H-22K are each arranged at an angle of 45 degrees with respect to the direction of laser beam 8, and the direction of laser beam 8 is changed by 90 degrees to form turning portions T1-T4. That is, in the first and third embodiments, two mirrors are arranged for each turning portion, but in the optical system 44 of the fourth embodiment, turning portions T2 and T1 are each formed by one mirror 22L or one mirror 22M.

[0109] In this case, the directions of the laser beam 8 before and after each of the turning portions T1, T2 are not parallel, but by moving the position of the mirror 22L in the X direction as the irradiation unit 26, which is a movable optical component, moves in the X direction and adjusting the angles of the mirrors 22L, 22M, for example, it is possible to adjust the optical path length while suppressing fluctuations in the center of gravity. Note that in this case, the appropriate movement amount of the mirror 22L relative to the movement amount of the irradiation unit 26 in the X direction and the appropriate angles of the mirrors 22L, 22M differ depending on the positional relationship between the mirrors 22L and 22M.

[0110] 7 is a perspective view showing yet another example (fifth embodiment) of the configuration of the optical processing device. In the first to fourth embodiments, the moving direction of the irradiation unit 26, which is a movable optical component, was assumed to be only along the X direction, but the optical processing device (laser processing device) 52 and optical system 54 of this fifth embodiment assume a mechanism in which the irradiation unit 26 moves in two directions, along the X direction and along the Y direction with respect to the horizontal direction, and are provided with a mechanism for adjusting the optical path length while suppressing fluctuations in the center of gravity with respect to each movement.

[0111] The laser processing apparatus 52 of this fifth embodiment is equipped with an X-axis moving mechanism 56 and a Y-axis moving mechanism 58 as an irradiation section moving mechanism that moves the irradiation unit 26 horizontally relative to the chuck table 16 that holds the workpiece 4.

[0112] The X-axis moving mechanism 56 and the Y-axis moving mechanism 58 have the same structure as the irradiation unit moving mechanism 28 in the first embodiment (see FIG. 1), for example.

[0113] The X-axis movement mechanism 56 and the Y-axis movement mechanism 58 are supported by a support frame 62 that entirely constitutes a support mechanism 60. The support frame 62 forms a support surface 62a along the YZ plane, to which the Y-axis movement mechanism 58 is attached, and further, the X-axis movement mechanism 56 is attached to the Y-axis movement mechanism 58.

[0114] The Y-axis moving mechanism 58 has a pair of Y-axis guide rails 58a extending parallel to each other along the Y direction on the support surface 62a of the support frame 62, and a Y-axis moving table 58b having a surface along the YZ plane is slidably mounted on the pair of Y-axis guide rails 58a.

[0115] A Y-axis ball screw 58c is disposed between the pair of Y-axis guide rails 58a and along the longitudinal direction of the Y-axis guide rails 58a. The Y-axis ball screw 58c passes through a nut (not shown) provided on the back surface of the Y-axis moving table 58b (the surface facing the support surface 62a of the support frame 62). A Y-axis pulse motor 58d is connected to one end of the Y-axis ball screw 58c, and operation of the Y-axis pulse motor 58d moves the Y-axis moving table 58b in the Y direction.

[0116] An X-axis movement mechanism 56 is attached to a Y-axis movement table 58b of the Y-axis movement mechanism 58. The X-axis movement mechanism 56 includes an X-axis guide rail 56a, an X-axis movement table 56b, an X-axis ball screw 56c, an X-axis pulse motor 56d, and a base 56e that supports these elements.

[0117] The base portion 56e is attached to the front side of the Y-axis moving table 58b and is a member having a surface along the XZ plane. A pair of X-axis guide rails 56a extending parallel to each other in the X direction is provided on the surface of the base portion 56e on the near side in the Y direction, and an X-axis moving table 56b having a surface along the XZ plane is slidably mounted on the pair of X-axis guide rails 56a.

[0118] An X-axis ball screw 56c is disposed between the pair of X-axis guide rails 56a and along the longitudinal direction of the X-axis guide rails 56a. The X-axis ball screw 56c passes through a nut (not shown) provided on the back surface (the surface facing the base portion 56e) of the X-axis moving table 56b. An X-axis pulse motor 56d is connected to one end of the X-axis ball screw 56c, and operation of the X-axis pulse motor 56d moves the X-axis moving table 56b in the X direction.

[0119] An irradiation unit 26 incorporating a mirror 22E and a condenser lens 24 is attached to the X-axis moving table 56b.

[0120] In this way, the irradiation unit 26, which is a movable optical component, is configured to be movable in the X-axis direction by the X-axis moving mechanism 56, which is an irradiation unit moving mechanism, and is also configured to be movable in the Y-axis direction together with the X-axis moving mechanism 56 by the Y-axis moving mechanism 58, which is an irradiation unit moving mechanism.

[0121] In addition, in the fifth embodiment, mirrors 22N to 22V are provided as optical elements that constitute the optical system .

[0122] 7, a laser beam 8 is emitted toward the front (forward) along the Y direction from a laser oscillator 18 arranged at the back right of the laser oscillator 18, and is reflected downward by a mirror 22N arranged in front of the laser oscillator 18. The laser beam 8 reflected downward by the mirror 22N is reflected toward the back (rear) by a mirror 22O arranged below the mirror 22N.

[0123] The laser beam 8 reflected backward by the mirror 22O is reflected downward by the mirror 22P arranged behind the mirror 22O. The laser beam 8 reflected downward by the mirror 22P is reflected forward by the mirror 22Q arranged below the mirror P, and then reflected to the right along the X direction by the mirror 22R arranged in front of the mirror 22Q.

[0124] The laser beam 8 reflected to the right by the mirror 22R is reflected downward by the mirror 22S disposed to the right of the mirror 22R. The laser beam 8 reflected downward by the mirror 22S is reflected to the left by the mirror 22T disposed below the mirror 22S.

[0125] The laser beam 8 reflected to the left by the mirror 22T is reflected downward by the mirror 22U disposed to the left of the mirror 22T. The laser beam 8 reflected downward by the mirror 22U is reflected to the right by the mirror 22V disposed below the mirror 22U.

[0126] To the right of mirror 22V is positioned irradiation unit 26. Laser beam 8 reflected to the right by mirror 22V is incident on mirror 22E in irradiation unit 26, reflected downward by mirror 22E, passes through condenser lens 24, and is irradiated onto workpiece 4 below by irradiation head 26a.

[0127] Of these mirrors 22N to 22V that make up the optical system 54, mirrors 22N to 22R are installed along a support surface 62a of a support frame 62 that forms a surface along the YZ plane, together with the laser oscillator 18. Furthermore, among these mirrors, mirrors 22N and 22O are installed so as to be movable along the Y axis relative to the support surface 62a by a Y-axis movement mechanism 66 that serves as an adjustment movement mechanism.

[0128] Mirrors 22S to 22V are installed along a base portion 56e of X-axis movement mechanism 56, which forms a surface along the XZ plane. Furthermore, mirrors 22S and 22T are installed so as to be movable along the surface of base portion 56e by an X-axis movement mechanism 64, which serves as an adjustment movement mechanism.

[0129] The X-axis movement mechanism 64 and the Y-axis movement mechanism 66 serving as the adjustment movement mechanism can be configured as mechanisms generally similar to the X-axis movement mechanism 56 and the Y-axis movement mechanism 58 serving as the irradiation unit movement mechanism, for example, as described below.

[0130] The X-axis moving mechanism 64 has a pair of X-axis guide rails 64a that extend parallel to each other along the X direction on the surface formed by the base portion 56e, and an X-axis moving table 64b that forms a surface along the XZ plane is slidably mounted on the pair of X-axis guide rails 64a.

[0131] An X-axis ball screw 64c is disposed between the pair of X-axis guide rails 64a and along the longitudinal direction of the X-axis guide rails 64a. The X-axis ball screw 64c passes through a nut (not shown) provided on the back surface (the surface facing the base 56e) of the X-axis moving table 64b. An X-axis pulse motor 64d is connected to one end of the X-axis ball screw 64c, and operation of the X-axis pulse motor 64d moves the X-axis moving table 64b in the X direction.

[0132] Mirrors 22S and 22T are attached to the top and bottom of X-axis moving table 64b, which constitutes X-axis moving mechanism 64 as an adjustment moving mechanism. Mirrors 22U and 22V are attached to Y-axis moving table 58b, which constitutes Y-axis moving mechanism 58 as an irradiation unit moving mechanism.

[0133] The Y-axis moving mechanism 66 has a pair of Y-axis guide rails 66a extending parallel to each other along the Y direction on the support surface 62a of the support frame 62, and a Y-axis moving table 66b having a surface along the YZ plane is slidably mounted on the pair of Y-axis guide rails 66a.

[0134] A Y-axis ball screw 66c is disposed between the pair of Y-axis guide rails 66a and along the longitudinal direction of the Y-axis guide rails 66a. The Y-axis ball screw 66c passes through a nut (not shown) provided on the back surface (the surface facing the support surface 62a) of the Y-axis moving table 66b. A Y-axis pulse motor 66d is connected to one end of the Y-axis ball screw 66c, and operation of the Y-axis pulse motor 66d moves the Y-axis moving table 66b in the Y direction.

[0135] Mirrors 22N and 22O are attached to the top and bottom of a Y-axis moving table 66b that constitutes a Y-axis moving mechanism 66 serving as an adjustment moving mechanism.

[0136] 8 and 9 are conceptual diagrams showing the layout of the optical system 54 in the optical processing device of the fifth embodiment shown in FIG. 7, and show the layout as seen from the Y direction and the X direction, respectively.

[0137] 8, in the X direction (left-right direction), as viewed from the irradiation unit 26, which is a movable optical component, two return portions T1 and T2 are formed between the irradiation unit 26 and the laser oscillator 18, which is located most upstream in the optical path of the laser beam 8. Of these, the first return portion T1 is formed by mirrors 22U and 22V, and the second return portion T2 is formed by mirrors 22S and 22T.

[0138] The mirrors 22S, 22T constituting the even-numbered turning portions T2 are configured to be movable along the X direction by an X-axis movement mechanism 64 (see FIG. 7) serving as an adjustment movement mechanism. This makes it possible to adjust the optical path length while suppressing fluctuations in the center of gravity as the irradiation unit 26 moves along the X direction.

[0139] 9, in the Y direction (front-rear direction), as viewed from the irradiation unit 26, which is a movable optical component, two return portions T1 and T2 are formed between the irradiation unit 26 and the laser oscillator 18, which is located most upstream in the optical path of the laser beam 8. Of these, the first return portion T1 is formed by mirrors 22P and 22Q, and the second return portion T2 is formed by mirrors 22N and 22O.

[0140] The mirrors 22N, 22O constituting the even-numbered turning portions T2 are configured to be movable along the Y direction by a Y-axis movement mechanism 66 (see FIG. 7) serving as an adjustment movement mechanism. This makes it possible to adjust the optical path length while suppressing fluctuations in the center of gravity as the irradiation unit 26 moves along the Y direction.

[0141] In addition, the above-described embodiments may be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0142] 2: Optical processing equipment (laser processing equipment) 4: object to be treated, 4a: frame, 4b: adhesive sheet, 6: object to be treated holding mechanism 8: laser beam, 10: irradiation mechanism, 12: base 14: moving mechanism, 14a: Y-axis guide rail, 14b: Y-axis moving table 14c: Y-axis ball screw, 14d: Y-axis pulse motor 16: Holding mechanism (chuck table), 16a: Holding surface 18: Light source (laser oscillator), 20: Optical system 22A: Optical element (mirror), 22B: Optical element (mirror) 22C: Optical element (mirror), 22D: Optical element (mirror) 22E: Optical element (mirror), 22F: Optical element (mirror) 22G: Optical element (mirror), 22H: Optical element (mirror) 22I: Optical element (mirror), 22J: Optical element (mirror) 22K: Optical element (mirror), 24: Optical element (condenser lens) 26: Movable optical component (illumination unit), 26a: Illumination head 28: Irradiation unit moving mechanism, 28a: X-axis guide rail, 28b: X-axis moving table 28c: X-axis ball screw, 28d: X-axis pulse motor 30: Adjustment movement mechanism, 30a: X-axis guide rail, 30b: X-axis movement table 30c: X-axis ball screw, 30d: X-axis pulse motor 32: Support mechanism, 34: Support frame, 34a: Support surface, 36: Controller 38: Optical system, 40: Optical element (polarized beam splitter), 40a: Wave plate 42:Optical system, 44:Optical system 52: Optical processing device (laser processing device), 54: Optical system 56: irradiation unit moving mechanism (X-axis moving mechanism), 56a: X-axis guide rail, 6b: X-axis moving table, 56c: X-axis ball screw, 56d: X-axis pulse motor 56e: Base 58: Irradiation unit moving mechanism (Y-axis moving mechanism), 58a: Y-axis guide rail 58b: Y-axis moving table, 58c: Y-axis ball screw, 58d: Y-axis pulse motor 60: Support mechanism, 62: Support frame, 62a: Support surface 64: Adjustment movement mechanism (X-axis movement mechanism), 64a: X-axis guide rail 64b: X-axis moving table, 64c: X-axis ball screw, 64d: X-axis pulse motor 66: Adjustment movement mechanism (Y-axis movement mechanism), 66a: Y-axis guide rail 66b: Y-axis moving table, 66c: Y-axis ball screw, 66d: Y-axis pulse motor T1: Turned part, T2: Turned part, T3: Turned part, T4: Turned part

Claims

1. a laser oscillator that emits a laser beam; an irradiation unit that irradiates a workpiece with the laser beam emitted from the laser oscillator; an irradiation unit moving mechanism that moves the irradiation unit; a plurality of optical elements arranged on an optical path of the laser beam emitted from the laser oscillator and guiding the laser beam from the laser oscillator to the irradiation unit; an adjustment movement mechanism that moves the optical element in a movement direction of the irradiation unit; An optical processing device configured to adjust the optical path length of the laser beam by moving the optical element with the adjustment movement mechanism in the opposite direction to the movement of the irradiation unit as the irradiation unit moves.

2. The plurality of optical elements are arranged in the optical path of the laser beam so that two or more turning portions are formed in the optical path of the laser beam in the moving direction of the irradiation unit, and 2. The optical processing device according to claim 1, wherein the optical elements constituting the even-numbered turning portions counting from the irradiation unit along the optical path of the laser beam are configured to be movable by the adjustment movement mechanism.

3. An optical system that includes a plurality of optical elements on an optical path and guides light to an irradiated portion, a movable optical component that is provided on the optical path and moves to vary the optical path; an adjustment movement mechanism that moves the optical element in the movement direction of the movable optical component; An optical system configured to adjust the optical path length of the laser beam by moving the optical element with the adjustment movement mechanism in the opposite direction to the movable optical component with respect to the movement direction of the movable optical component as the movable optical component moves.

4. The plurality of optical elements are arranged to form two or more turning portions in the optical path with respect to the moving direction of the movable optical component, and 4. The optical system according to claim 3, wherein the optical elements constituting the even-numbered folded portions counted from the movable optical component along the optical path are configured to be movable by the adjustment movement mechanism.

5. a direction of incidence of light along the optical path onto the movable optical component is parallel to a direction of movement of the movable optical component; The plurality of optical elements include at least first to fourth reflective optical elements on the upstream side of the movable optical component, light is incident on the first reflective optical element in the same direction as the incident direction of the light on the movable optical component, with respect to the moving direction of the movable optical component; In the first reflective optical element, light is reflected in a direction intersecting with the moving direction of the movable optical component and is incident on the second reflective optical element, In the second reflective optical element, the light is reflected in a direction opposite to the direction of incidence of the light on the movable optical component with respect to the moving direction of the movable optical component, and is then incident on the third reflective optical element; The third reflective optical element is configured so that light is reflected in a direction intersecting with the moving direction of the movable optical component and is incident on the fourth reflective optical element.

5. The optical system according to claim 3 or 4.

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