Laser beam machining device

Abstract

To provide a laser beam machining device in which a condenser lens can be easily replaced.SOLUTION: A laser beam machining device for emitting a laser beam to a workpiece comprises: a laser oscillator; a plurality of condenser lenses, each including: at least one lens for condensing the laser beam emitted from the laser oscillator; and a lens barrel in which the at least one lens is fixed; and a holder base that is rotatable about a predetermined rotation axis and holds the plurality of condenser lenses arranged along a circumferential direction of the rotation axis. By means of the rotation of the holder base around the rotation axis, one of the plurality of condenser lenses is selectively disposed on an optical path of the laser beam that is emitted to the workpiece.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a laser processing apparatus that irradiates a workpiece with a laser beam. [Background technology]

[0002] 2. Description of the Related Art A method is known in which a laser beam is focused by a focusing lens and irradiated along a planned dividing line of a semiconductor wafer to divide the semiconductor wafer into a plurality of chips by ablation (see, for example, Patent Document 1).

[0003] In such laser processing, it is important to select and use an appropriate condenser lens according to the material, thickness, etc. of the workpiece. Usually, a laser processing device is equipped with one condenser lens that is optimized for processing a given material, thickness, etc.

[0004] Therefore, when performing laser processing on a workpiece under processing conditions different from the processing conditions achieved using one focusing lens, the worker must manually replace the one focusing lens with another focusing lens each time.

[0005] When replacing a focusing lens, an operator must remove one focusing lens, install another focusing lens, and adjust the relative position of the installed focusing lens and the optical path of the laser beam, which results in a problem of taking a relatively large amount of time and effort. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2003-320466 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above problems, and has an object to provide a laser processing apparatus in which the condenser lens can be easily replaced. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a laser processing apparatus that irradiates a laser beam onto a workpiece, the laser processing apparatus comprising: a laser oscillator; a plurality of focusing lenses, each of which has one or more lenses for focusing the laser beam emitted from the laser oscillator and a barrel in which the one or more lenses are fixed; and a holder base that is rotatable around a predetermined rotation axis and holds the plurality of focusing lenses arranged along the circumferential direction of the rotation axis, wherein rotation of the holder base around the rotation axis selectively positions one of the plurality of focusing lenses on the optical path of the laser beam irradiated to the workpiece.

[0009] Preferably, the holder base includes a plurality of first positioning members provided on an outer surface of the holder base so as to have a one-to-one correspondence with the plurality of focusing lenses, and the laser processing apparatus further includes a second positioning member that determines a position of any one of the plurality of first positioning members in the circumferential direction of the rotation axis by contacting the one first positioning member when rotating the holder base around the rotation axis to selectively position one of the plurality of focusing lenses on the optical path of the laser beam, and a moving mechanism that, when determining the position of the one first positioning member in the circumferential direction of the rotation axis, moves either one or both of the one first positioning member and the second positioning member relatively in a direction different from the circumferential direction of the rotation axis, thereby realizing a contact state in which the one first positioning member and the second positioning member are in contact and a non-contact state in which the one first positioning member and the second positioning member are not in contact.

[0010] In addition, preferably, the laser processing apparatus further includes a rotational drive source that rotates the holder base around the rotation axis, and a controller that controls the operation of the rotational drive source, and the controller controls the operation of the rotational drive source to rotate the holder base and then operates the moving mechanism, thereby realizing the contact state in which the one first positioning member and the second positioning member are in contact.

[0011] In addition, preferably, the positions of the one or more lenses in each barrel are predetermined so that the focal point of the laser beam focused by each of the plurality of focusing lenses is located at a predetermined position in a first direction parallel to the optical axis of each focusing lens selectively arranged on the optical path of the laser beam.

[0012] Also, preferably, each of the plurality of focusing lenses has the same numerical aperture, a different focal length, and a different entrance pupil diameter, and the controller selectively positions one of the plurality of focusing lenses on the optical path of the laser beam in response to a focal depth and a focusing density of the laser beam that are determined according to processing conditions for the workpiece with the laser beam. Effect of the Invention

[0013] In a laser processing apparatus according to one embodiment of the present invention, by rotating a holder base around a rotation axis, one of a plurality of focusing lenses is selectively positioned on the optical path of a laser beam irradiated to a workpiece.

[0014] This eliminates the need for an operator to remove and attach the condenser lens and adjust the relative position between the condenser lens and the optical path of the laser beam, thereby making it possible to easily replace the condenser lens. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a perspective view of the laser processing device. [Diagram 2] FIG. [Diagram 3] FIG. 2 is an exploded perspective view of the condenser lens unit. [Figure 4] FIG. 4A is a plan view of the condenser lens unit before the pins are positioned, and FIG. 4B is a plan view of the condenser lens unit after the pins are positioned. [Diagram 5] FIG. 4B is a cross-sectional view taken along line AA of FIG. [Figure 6] FIG. 2 is a perspective view of the bottom side of the disassembled condenser lens unit. [Figure 7] FIG. 4 is a diagram showing the focusing positions of each focusing lens. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view of a laser processing apparatus 2. In Fig. 1, some of the components of the laser processing apparatus 2 are shown in functional blocks.

[0017] The X-axis direction, Y-axis direction, and Z-axis direction shown in Fig. 1 are mutually perpendicular. The X-axis direction is approximately parallel to the processing feed direction, and the Y-axis direction is approximately parallel to the indexing feed direction. The Z-axis direction is approximately parallel to the height direction (vertical direction).

[0018] The X-axis direction is parallel to the +X and -X directions which are opposite to each other, the Y-axis direction is parallel to the +Y and -Y directions which are opposite to each other, and the Z-axis direction is parallel to the +Z and -Z directions which are opposite to each other.

[0019] The laser processing device 2 is provided with a base 4 that supports its components. The base 4 includes a flat base 6 and an upright portion 8 located behind the base 6 (on one side in the Y-axis direction). The base 6 is provided with a chuck table 10 that holds a workpiece 11 by suction.

[0020] The workpiece 11 includes, for example, a wafer such as a silicon single crystal substrate. The thickness of the wafer is not particularly limited, but the wafer has a thickness of, for example, 200 μm or more and 800 μm or less. The workpiece 11 may or may not include devices such as an integrated circuit (IC) or a light emitting diode (LED).

[0021] During laser processing, the workpiece 11 is supported by the metal annular frame 17 via the resin tape 15. In other words, the workpiece 11 is suction-held by the chuck table 10 via the tape 15 in the form of a workpiece unit 19 integrated with the tape 15 and the annular frame 17.

[0022] The chuck table 10 has a disk-shaped frame made of metal. A disk-shaped recess having a smaller diameter than the frame is formed in the upper part of the frame, and a disk-shaped porous plate made of porous ceramics is fixed in the recess.

[0023] The frame has a predetermined flow path (not shown) for supplying negative pressure to the porous plate, and the predetermined flow path is connected to a suction source (not shown) such as a vacuum pump via a pipe (not shown). The upper surface of the porous plate and the upper surface of the frame are substantially flush with each other and form a substantially flat holding surface 10a.

[0024] A plurality of clamp units 10b (four in this embodiment) are arranged at substantially equal intervals along the circumferential direction of the frame on the outer periphery of the frame. Each clamp unit 10b is capable of clamping an annular frame 17 of a workpiece unit 19.

[0025] When the workpiece 11 is held by suction on the holding surface 10a, negative pressure is transmitted from the suction source to the porous plate to hold the workpiece 11 by suction on the holding surface 10a, and the annular frame 17 is clamped by each clamp unit 10b.

[0026] A ball screw type Y-axis direction moving mechanism 12 for moving the chuck table 10 along the Y-axis direction is provided below the chuck table 10. The Y-axis direction moving mechanism 12 has a pair of Y-axis guide rails 14 that are fixed to the upper surface of the base 6 and arranged substantially parallel to the Y-axis direction.

[0027] A Y-axis direction moving table 16 is slidably fixed to the Y-axis guide rail 14. A nut portion (not shown) is provided on the lower surface of the Y-axis direction moving table 16, and a screw shaft 18 arranged substantially parallel to the Y-axis direction is rotatably coupled to this nut portion via a plurality of balls (not shown).

[0028] A driving source 20 such as a stepping motor is connected to one end of the screw shaft 18. When the screw shaft 18 is rotated by the driving source 20, the Y-axis moving table 16 moves along the Y-axis direction. A ball screw type X-axis moving mechanism 22 that moves the chuck table 10 along the X-axis direction is provided on the upper surface of the Y-axis moving table 16.

[0029] The X-axis direction moving mechanism 22 includes a pair of X-axis guide rails 24 that are fixed to the upper surface of the Y-axis direction moving table 16 and arranged substantially parallel to the X-axis direction. An X-axis direction moving table 26 is slidably fixed to the X-axis guide rails 24.

[0030] A nut portion (not shown) is provided on the underside of the X-axis direction moving table 26, and a screw shaft 28 arranged substantially parallel to the X-axis direction is rotatably coupled to the nut portion. One end of the screw shaft 28 is connected to a driving source 30 such as a stepping motor.

[0031] When the screw shaft 28 is rotated by the driving source 30, the X-axis direction moving table 26 moves along the X-axis direction. A cylindrical support base 32 is provided on the upper surface side of the X-axis direction moving table 26. The above-mentioned chuck table 10 is disposed on the upper portion of the support base 32.

[0032] A drive source (not shown) such as a motor is provided inside the support base 32, and rotates the chuck table 10 around a rotation axis parallel to the Z-axis direction as necessary. The standing portion 8 is provided with a Z-axis direction moving mechanism 34.

[0033] The Z-axis direction moving mechanism 34 has a pair of Z-axis guide rails 36 fixed to the standing portion 8. Note that one Z-axis guide rail 36 is shown in Fig. 1. A Z-axis direction moving plate 38 is slidably attached to the pair of Z-axis guide rails 36.

[0034] A nut portion (not shown) is provided on the back surface of the Z-axis direction moving plate 38, and a screw shaft (not shown) arranged approximately parallel to the Z-axis direction is rotatably connected to the nut portion via a plurality of balls (not shown).

[0035] A driving source 40 such as a stepping motor is connected to the upper end of the screw shaft. When the screw shaft is rotated by the driving source 40, the Z-axis direction moving plate 38 moves along the Z-axis direction. A support 42 is fixed to the surface of the Z-axis direction moving plate 38.

[0036] The support 42 supports a cylindrical housing 46 that constitutes the laser beam irradiation unit 44. In this embodiment, a laser oscillator 48 is disposed inside the housing 46. However, the laser oscillator 48 may be disposed outside the housing 46.

[0037] The laser oscillator 48 has a laser medium such as an Nd:YAG crystal, and further has an excitation light source such as a lamp that irradiates the laser medium with excitation light, and a Q switch that controls the timing at which the laser beam L is emitted.

[0038] A pulsed laser beam L having a predetermined wavelength (e.g., 1064 nm) is emitted from the laser oscillator 48. After being emitted from the laser oscillator 48, the laser beam L is converted by a nonlinear optical crystal (not shown) arranged in the housing 46 into a predetermined wavelength (e.g., 355 nm) that can process the workpiece 11.

[0039] The laser beam L converted to a predetermined wavelength is incident on a head unit 50 provided at the tip of the housing 46. The housing 46 may be provided with a beam shaper (not shown) for adjusting the beam intensity distribution, beam shape, etc., a DOE (Diffractive Optical Element) (not shown) for spatially branching the laser beam L, and the like.

[0040] The laser beam L incident on the head portion 50 is reflected by a mirror 58 (see FIG. 2) so that its direction of travel is changed from the Y-axis direction to the Z-axis direction, and then the laser beam L is irradiated from the head portion 50 along the Z-axis direction toward the holding surface 10a.

[0041] In the drawings, the dashed dotted line indicating the laser beam L may be regarded as an optical path 82 of the laser beam L (see FIGS. 2 and 3). An imaging unit 52 is provided on the side of the housing 46 near the tip thereof.

[0042] The imaging unit 52 is, for example, a microscope camera unit, and includes an objective lens, a light source, and a solid-state imaging element, all of which are not shown. The objective lens is disposed so as to face the holding surface 10a of the chuck table 10.

[0043] The light source has, for example, a white LED capable of emitting light in the visible light band. The solid-state imaging element is a charge-coupled device (CCD) image sensor or a complementary metal-oxide-semiconductor (CMOS) image sensor. The imaging unit 52 is capable of capturing an image of the surface 11a of the workpiece 11 held by the holding surface 10a.

[0044] Meanwhile, a cover (not shown) that covers the components of the laser processing device 2 is provided on the base 4. A touch panel 54 is provided on the front side (the other side in the Y-axis direction) of the cover. The touch panel 54 is a liquid crystal display including a capacitive touch sensor.

[0045] The touch panel 54 functions as an input device with which the operator inputs instructions to the laser processing apparatus 2, and also functions as a GUI (Graphical User Interface) for inputting instructions and a display device for displaying images obtained by the imaging unit 52, etc.

[0046] The laser processing apparatus 2 is provided with a controller 56 that controls the operation of the Y-axis direction moving mechanism 12, the X-axis direction moving mechanism 22, the drive source in the support base 32, the Z-axis direction moving mechanism 34, the suction source, the laser beam irradiation unit 44, the imaging unit 52, the touch panel 54, etc.

[0047] The controller 56 is configured by a computer having a processor 56a, such as a CPU (Central Processing Unit), and a memory 56b. The memory 56b includes a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a flash memory.

[0048] The auxiliary storage device stores software including a predetermined program. The functions of the controller 56 are realized by operating the processor 56a in accordance with this software. Next, the structure of the head unit 50 will be described with reference to Figs. 2 to 7.

[0049] 2 is an enlarged perspective view of the head unit 50. The head unit 50 has the above-mentioned mirror 58 for changing the path of the laser beam L from the Y-axis direction to the Z-axis direction. The laser beam L reflected by the mirror 58 is incident on the condenser lens unit 60.

[0050] 3 is an exploded perspective view of the condenser lens unit 60. The condenser lens unit 60 has a cylindrical housing 62 made of a metal such as stainless steel or an aluminum alloy. The housing 62 includes a circular top opening 62a and a bottom opening 62b having a smaller diameter than the top opening 62a.

[0051] The top opening 62a has three grooves 62d formed at approximately equal intervals along a circumferential direction 62c of the housing 62. The three grooves 62d are formed on the inner circumferential side surface of the housing 62 located in the vicinity of the top opening 62a.

[0052] The two grooves 62d are provided at positions sandwiching the center of the top opening 62a, and the remaining groove 62d is spaced apart from the two grooves 62d by approximately the same distance in the circumferential direction 62c of the housing 62.

[0053] A semicircular support plate 64 is fixed to the top opening 62a so as to cover approximately half of the top opening 62a. Three claws 64a are provided on the outer periphery of the support plate 64, and the claws 64a and the grooves 62d fit together in a one-to-one correspondence, thereby restricting movement of the support plate 64 in the circumferential direction 62c of the housing 62.

[0054] A stepping motor (rotation drive source) 66 is provided at the center of the top surface 64b of the support plate 64. The operation of the stepping motor 66 is controlled by the above-mentioned controller 56. The stepping motor 66 has a cylindrical rotation shaft 66a.

[0055] The rotating shaft 66a is disposed along the Z-axis direction and is inserted into a through-hole 64c (see FIG. 5) provided in the support plate 64 without contacting the support plate 64. The lower end of the rotating shaft 66a protrudes downward from a bottom surface 64d of the support plate 64.

[0056] In a plan view of the support plate 64, an air cylinder (movement mechanism) 68 is provided between one of a pair of claws 64a arranged to sandwich the rotation shaft 66a therebetween and the stepping motor 66. The operation of the air cylinder 68 is also controlled by the controller 56 described above.

[0057] The air cylinder 68 has a rod (not shown) that can advance and retreat substantially parallel to the top surface 64b of the support plate 64. The rod is disposed so as to cross a linear end portion 64e of the support plate 64, which has a semicircular shape in a plan view, when advancing and retreating, and an L-shaped plate 68a is fixed to the tip of the rod.

[0058] The L-shaped plate 68a has a horizontal plate 68a1 and a vertical plate 68a2 arranged so as to be perpendicular to each other. The horizontal plate 68a1 is arranged approximately parallel to the top surface 64b of the support plate 64, and covers the top of the air cylinder 68. The vertical plate 68a2 is fixed to the tip of the horizontal plate 68a1.

[0059] The tip of the rod described above is fixed to the rear surface of the vertical plate 68a2, and a positioning block (second positioning member) 70 is fixed to the front surface of the vertical plate 68a2. The positioning block 70 has a base plate 70a.

[0060] The base plate 70a has a back surface 70a1 and a front surface 70a2 (see FIG. 4(A)). As shown in FIG. 3, the width of the top of the base plate 70a is greater than the width of the bottom. The top of the base plate 70a is fixed to the vertical plate 68a2 by a fixing member such as a bolt, with the back surface 70a1 of the base plate 70a in contact with the front surface of the vertical plate 68a2.

[0061] The bottom of the base plate 70a protrudes downward below the bottom surface 64d of the support plate 64. A convex portion 70b having a width narrower than that of the bottom of the base plate 70a is provided on a surface 70a2 of the bottom of the base plate 70a and protrudes from the surface 70a2.

[0062] 4A, the protrusion 70b has a quadrangular prism shape with a top surface and a bottom surface each being a right-angled trapezoid, and the height direction of the protrusion 70b is disposed along the Z-axis direction. An inclined surface 70b1 of the protrusion 70b forms an obtuse angle θ with a surface 70a2 of the base plate 70a.

[0063] In this embodiment, the obtuse angle θ is a predetermined angle that is greater than 90° and smaller than 110°. The obtuse angle θ is, for example, 100°. The obtuse angle θ and the position of the protrusion 70b are appropriately adjusted according to the position of the pin 76 that is adjusted by precise alignment, which will be described later.

[0064] 3. A disk-shaped holder base 72 is provided below the support plate 64 in a manner that does not contact the base plate 70a and the protrusion 70b in the Z-axis direction (see FIG. 5). A shaft holder 74 is provided at the center of the circular top surface 72a of the holder base 72.

[0065] A rotating shaft 66a of a stepping motor 66 is fixed to a hole 74a of the shaft holder 74. When the stepping motor 66 is operated with the rotating shaft 66a fixed to the shaft holder 74, the holder base 72 rotates around the rotating shaft 66a. The rotation direction of the holder base 72 in a plan view may be either clockwise or counterclockwise.

[0066] A plurality of pins (first positioning members) 76 are provided at approximately equal intervals along a circumferential direction 72b of the holder base 72 on the outer periphery of a top face (outer surface) 72a of the holder base 72. Each pin 76 is arranged along the Z-axis direction.

[0067] The multiple pins 76 have a one-to-one correspondence with the multiple focusing lenses 78 described below, and one pin 76 is used to align one of the multiple focusing lenses 78 fixed to the holder base 72 to a predetermined position on the XY plane.

[0068] 4(A), when the rod of the air cylinder 68 is in a retracted position retracted into the cylinder tube (not shown), the positioning block 70 is in a position that does not interfere with the movement trajectory of the multiple pins 76 around the rotation shaft 66a. At this time, a non-contact state is realized in which the pins 76 and the positioning block 70 do not come into contact with each other.

[0069] 4(B), when the rod of the air cylinder 68 is in a protruding position by protruding a predetermined amount in a predetermined direction 70c in the XY plane different from the circumferential direction 66a1 (see FIG. 3) of the rotation shaft 66a, the positioning block 70 is in a position where it interferes with the movement trajectory of the multiple pins 76 around the rotation shaft 66a. At this time, a contact state is realized in which the pins 76 and the positioning block 70 come into contact with each other.

[0070] In this embodiment, when determining the position of any one pin 76 in the circumferential direction 66a1 of the rotation shaft 66a, first, the stepping motor 66 is operated to rotate the holder base 72, and the position of the desired one pin 76 is roughly determined in the XY plane (coarse alignment).

[0071] Then, after rotating the holder base 72, in order to realize a contact state in which one pin 76 and the positioning block 70 are in contact with each other, the air cylinder 68 moves the positioning block 70 relatively by a predetermined amount in a predetermined direction 70c.

[0072] When the rod of the air cylinder 68 is placed in the protruding position, one pin 76 comes into contact with the inclined surface 70b1 of the convex portion 70b and the surface 70a2 of the base plate 70a. This determines the position of the one pin 76 in the circumferential direction 66a1 of the rotation shaft 66a. That is, precise alignment is performed to align the one pin 76 with higher accuracy on the XY plane.

[0073] Incidentally, although the pins 76 in this embodiment do not move along the Z-axis direction, each pin 76 may be movable along the Z-axis direction by an actuator. For example, when performing positioning, one pin 76 to be positioned protrudes in the +Z direction, and all of the other pins 76 are partially or entirely housed within the holder base 72 so as not to come into contact with the positioning block 70.

[0074] Furthermore, when positioning of one pin 76 is not performed, all or some of the pins 76 are housed in the holder base 72 so as not to come into contact with the positioning block 70. When the pins 76 are movable along the Z-axis direction, the positioning block 70 has a cylindrical hole (not shown) into which the pins 76 that move to protrude in the +Z direction are fitted.

[0075] In order to fix the position of one pin 76 in the XY plane using a pin 76 that is movable along the Z-axis direction and a positioning block 70 having a hole, the position of the desired one pin 76 is first roughly determined in the XY plane by the stepping motor 66 (coarse alignment).

[0076] Next, the convex portion 70b is protruded as shown in Fig. 4(B), and the pin 76 located directly below the positioning block 70 is moved in the +Z direction. The pin 76 fits into the hole of the positioning block 70, whereby the position of the holder base 72 around the rotation axis 66a is finely corrected, and the pin 76 is precisely aligned within the XY plane.

[0077] In other words, the contact state between the one pin 76 and the positioning block 70 is realized by relatively moving both the one pin 76 and the positioning block 70 in a direction different from the circumferential direction 66a1 of the rotation shaft 66a.

[0078] 4B, the positioning block 70 may be fixed at the position shown in Fig. 4B, and each pin 76 may be moved along the Z-axis direction. In this case, a contact state between the pin 76 and the positioning block 70 is realized by moving only one pin 76 relative to the positioning block 70 in the Z-axis direction, which is different from the circumferential direction 66a1 of the rotation shaft 66a.

[0079] 3, the holder base 72 has a plurality of through holes 72d each penetrating from the top surface 72a to the bottom surface 72c. The through holes 72d are disposed at approximately equal intervals along the circumferential direction 72b of the holder base 72.

[0080] In this embodiment, one through hole 72d is disposed between each two pins 76 adjacent to each other in the circumferential direction 72b of the holder base 72. One condenser lens 78 is inserted into each through hole 72d.

[0081] As shown in Fig. 5, each condenser lens 78 has one or more lenses 78a and a lens barrel 78b in which the one or more lenses 78a are fixed. The condenser lens 78 may be interpreted as a lens assembly in which the one or more lenses 78a are fixed to the lens barrel 78b. Fig. 5 is a cross-sectional view taken along line AA in Fig. 4(B).

[0082] 5 representatively shows only lens 78a having a condensing function, but in a normal condensing lens 78, in addition to lens 78a, a lens (not shown) having an aberration correction function, an optical film (not shown), etc. are fixed inside lens barrel 78b. The positions of the one or more lenses 78a are predetermined in each lens barrel 78b.

[0083] By the function of one or more lenses 78a, the laser beam L emitted from the laser oscillator 48 is focused to approximately one point (focus point P) at a predetermined position in a first direction 78d parallel to the optical axis 78c of each focusing lens 78.

[0084] In this embodiment, the optical axes 78c of all the condenser lenses 78 are parallel to the Z-axis direction, but the optical axes 78c of all the condenser lenses 78 do not necessarily have to be parallel to the Z-axis direction. However, the optical axis 78c of one condenser lens 78 arranged in the optical path 82 of the laser beam L is usually arranged parallel to the Z-axis direction.

[0085] Fig. 6 is a perspective view of the bottom side of the disassembled condenser lens unit 60. As shown in Fig. 6, a flange 78e for fixing the condenser lens 78 to the holder base 72 is provided on the outer peripheral side surface of the lens barrel 78b of each condenser lens 78.

[0086] The flange 78e has a plurality of (in this embodiment, three) protrusions 78e1 each protruding along the radial direction of the lens barrel 78b, and an annular connecting portion 78e2 connecting the plurality of protrusions 78e1 in the circumferential direction of the flange 78e.

[0087] The multiple protrusions 78e1 are arranged at approximately equal intervals along the circumferential direction of the lens barrel 78b, and each protrusion has a through hole for screwing. The flange 78e is fixed to a fan-shaped holder 80 having a central angle of approximately 90 degrees.

[0088] Screw holes 80a1 are formed in the outer periphery of the bottom surface 80a of the holder 80 at positions corresponding to the through holes of the multiple protrusions 78e1. Also, a through hole 80a2 for inserting the condenser lens 78 is provided in the center of each holder 80, penetrating from the bottom surface 80a to the top surface 80b.

[0089] With the lens barrel 78b inserted into the through hole 80a2, when the screw shaft of a bolt (not shown) inserted into the through hole of each protrusion 78e1 is fastened to the screw hole 80a1 of the holder 80, the head of the bolt presses the protrusion 78e1. As a result, one condenser lens 78 is fixed to one holder 80.

[0090] Each holder 80 has a plurality of screw holes 80a1, one through hole 80a2, and at different positions, a plurality of (in this embodiment, two) holder fixing holes 80a3 that penetrate from the bottom surface 80a to the top surface 80b of the holder 80.

[0091] A plurality of (in this embodiment, eight (=2×4)) screw holes 72e are provided on the bottom surface 72c side of the holder base 72 so as to correspond one-to-one with the holder fixing holes 80a3. The diameter of the screw holes 72e is, for example, 4 mm, and a bolt (not shown) having a shaft diameter of 4 mm is fixed in the screw holes 72e.

[0092] When a bolt is fixed to the threaded hole 72e, the holder 80 is pressed and fixed to the holder base 72 by the bolt having a head diameter larger than that of the holder fixing hole 80a3. However, the diameter of the holder fixing hole 80a3 is larger than the diameter of the threaded hole 72e and the diameter of the bolt fastened to the threaded hole 72e.

[0093] The diameter of the holder fixing hole 80a3 is, for example, 6.5 mm, and the holder fixing hole 80a3 is a through hole that is not fastened to the shaft of a bolt. Therefore, by loosening the fastening of the bolt to the screw hole 72e, the position of the holder 80 (i.e., the condenser lens 78 fixed to the holder 80) can be finely adjusted within the bottom surface 72c of the holder base 72.

[0094] Such fine adjustment is performed, for example, during maintenance of the laser processing device 2, not when laser processing is performed on the workpiece 11 using the laser processing device 2. When performing fine adjustment, an operator first loosens the fastening of the bolt in the screw hole 72e.

[0095] Next, the bolts are tightened again after finely adjusting the position of the holder 80 within the bottom surface 72c of the holder base 72. This allows fine adjustment of the position of the condenser lens 78 so that the optical axis 78c of the condenser lens 78 approximately coincides with the optical path 82 of the laser beam L.

[0096] In this embodiment, four holders 80, each having one condenser lens 78 fixed thereto, are arranged to form a disk and fixed to the holder base 72. In other words, the four sets of condenser lenses 78 and holders 80 are fixed to the rotation shaft 66a of the stepping motor 66 via the holder base 72.

[0097] In this manner, the plurality of condenser lenses 78 are held by the holder base 72 in a state in which they are rotatable around the rotation shaft 66a and are arranged at substantially equal intervals along the circumferential direction 66a1 of the rotation shaft 66a.

[0098] In the laser processing device 2, when one condenser lens 78 is selectively disposed on the optical path 82 of the laser beam L, the position of the condenser lens 78 is adjusted in two stages, that is, the rough alignment and the fine alignment, as described above.

[0099] Specifically, first, the controller 56 controls the operation of the stepping motor 66 to rotate the holder base 72 around the rotation axis 66a (coarse alignment), thereby aligning the position of the focusing lens 78 onto the optical path 82 using only the stepping motor 66.

[0100] FIG. 4A is a plan view of the condenser lens unit 60 after the holder base 72 has been rotated using only the stepping motor 66 and before the position of the pin 76 has been determined by the positioning block 70 (that is, during rough alignment).

[0101] After the rough alignment, as shown in FIG. 4(B), the controller 56 controls the operation of the air cylinder 68 to protrude the positioning block 70 and bring any one of the multiple pins 76 into contact with the positioning block 70.

[0102] As a result, the position of one pin 76 is determined in the circumferential direction 66a1 of the rotation shaft 66a by the positioning block 70, and the optical axis 78c of one condenser lens 78 is precisely aligned with the optical path 82 of the laser beam L (precise alignment).

[0103] 4(B) is a plan view of the condenser lens unit 60 after the position of the pin 76 has been determined by the positioning block 70. After precise alignment, the laser beam L emitted from the laser oscillator 48 is irradiated onto the workpiece 11 that is sucked and held by the holding surface 10a.

[0104] In contrast, when replacing the condenser lens 78, first, the rod of the air cylinder 68 is placed in the retracted position. As a result, as shown in Fig. 4(A), the positioning block 70 is placed in a position that does not interfere with the movement trajectories of the multiple pins 76. Next, as described above, rough alignment and fine alignment are sequentially performed for the other condenser lenses 78 to be used.

[0105] In this embodiment, by rotating the holder base 72 around the rotation axis 66a, one of the multiple focusing lenses 78 is selectively positioned on the optical path 82 of the laser beam L irradiated to the workpiece 11.

[0106] This eliminates the need for an operator to remove and attach the condenser lens 78 and adjust the relative position between the condenser lens 78 and the optical path 82 of the laser beam L. This makes it possible to easily replace the condenser lens 78.

[0107] As described above, the positions of one or more lenses 78a in each lens barrel 78b are predetermined so that the positions in the first direction 78d of the focusing point P of the laser beam L focused by each focusing lens 78 selectively arranged on the optical path 82 of the laser beam L are approximately the same as shown in Figure 7.

[0108] Fig. 7 is a diagram showing the position in the Z-axis direction of the focusing point P of each focusing lens 78. However, for convenience of explanation, in Fig. 7, the holder base 72, the flange 78e, the holder 80, etc. are omitted, and the four focusing lenses 78 are shown lined up in a row.

[0109] In reality, the laser beam L is incident on only one condenser lens 78, but for convenience of explanation, FIG. 7 shows each condenser point P formed by each condenser lens 78 on the same page.

[0110] In FIG. 7, for convenience of explanation, the four condenser lenses 78 are divided into condenser lenses 78-1, 78-2, 78-3, and 78-4, and the condenser point P is divided into condenser points P1, P2, P3, and P4.

[0111] Each of the four condenser lenses 78-1, 78-2, 78-3, and 78-4 has a different focal length and a different entrance pupil diameter, but has the same numerical aperture (ie, NA (Numerical Aperture)).

[0112] For example, the focal length f1 of the condenser lens 78-1 is 40 mm, the focal length f2 of the condenser lens 78-2 is 60 mm, the focal length f3 of the condenser lens 78-3 is 80 mm, and the focal length f4 of the condenser lens 78-4 is 100 mm.

[0113] The entrance pupil diameter R1 of the condenser lens 78-1 is 24 mm, the entrance pupil diameter R2 of the condenser lens 78-2 is 36 mm, the entrance pupil diameter R3 of the condenser lens 78-3 is 48 mm, and the entrance pupil diameter R4 of the condenser lens 78-4 is 60 mm.

[0114] In this case, the four condenser lenses 78-1 to 78-4 each have the same numerical aperture. Specifically, the numerical aperture NA1 of the condenser lens 78-1 is expressed as sin(arctan(R1 / 2f1)) and is approximately 0.29.

[0115] Based on a similar calculation method, the numerical aperture NA2 of the condenser lens 78-2, the numerical aperture NA3 of the condenser lens 78-3, and the numerical aperture NA4 of the condenser lens 78-4 are each approximately 0.29.

[0116] By the way, the entrance pupil diameter of the condenser lens 78 is equal to the beam diameter R of the laser beam L. L (not shown), the greater the effective numerical aperture for the laser beam L. In addition, the entrance pupil diameter of the condenser lens 78 is smaller than the beam diameter R of the laser beam L. L The larger θ is, the smaller the effective numerical aperture for the laser beam L becomes.

[0117] For example, the beam diameter R of a laser beam L L is 24 mm, the effective numerical aperture NA of the condenser lens 78-1 having an entrance pupil diameter R1 of 24 mm is1’ is sin(arctan(R L / 2f1), which is approximately 0.29.

[0118] In contrast, based on a similar calculation method, the effective numerical aperture NA of the condenser lens 78-2 with an entrance pupil diameter R2 of 36 mm is 2’ is approximately 0.20, and the effective numerical aperture NA of the condenser lens 78-3 with an entrance pupil diameter R3 of 48 mm is 3’ is approximately 0.15, and the effective numerical aperture NA of the condenser lens 78-4 with an entrance pupil diameter R4 of 60 mm is 4’ is approximately 0.12.

[0119] Regarding the four condenser lenses 78-1, 78-2, 78-3, and 78-4 described above, the performance of each condenser lens 78, such as the numerical aperture NA, and the beam diameter R L For a laser beam L with effective numerical aperture NA n’ etc. are shown in Table 1. In Table 1, the subscript n is a natural number between 1 and 4.

[0120] [Table 1]

[0121] Like the condenser lens 78-1, the effective numerical aperture NA for the laser beam L is n’ The larger the NA, the smaller the focal depth, but the greater the light density. n’ The condenser lens 78 having a large diameter is suitable for processing only the vicinity of the surface 11a of the workpiece 11.

[0122] In contrast, the effective numerical aperture NA of the condenser lens 78-4 is n’ The smaller the condensed light density, the greater the focal depth. Therefore, the effective numerical aperture NA n’ The condenser lens 78 having a small diameter is suitable for simultaneously machining a wider area in the thickness direction of the workpiece 11 .

[0123] When the operator specifies processing conditions via the touch panel 54, the above-mentioned controller 56 places the condenser lens 78 corresponding to the processing conditions on the optical path 82 of the laser beam L. For example, when ablation processing is performed on a circuit layer (not shown) of a predetermined thickness formed in the vicinity of the surface 11a, the controller 56 selects the condenser lens 78-1.

[0124] Furthermore, for example, when ablation processing is performed on a layer, film, substrate, or the like (not shown) having a predetermined thickness provided between the front surface 11a and the back surface 11b, the controller 56 selects the condenser lens 78-4.

[0125] In this manner, the controller 56 selectively positions one of the multiple focusing lenses 78-1 to 78-4 on the optical path 82 of the laser beam L in accordance with the focal depth and focusing density of the laser beam L, which are determined according to the processing conditions of the laser beam L on the workpiece 11.

[0126] Therefore, the laser processing conditions can be changed by the worker simply selecting one of the multiple focusing lenses 78 to be used, without the worker having to remove and attach each focusing lens 78, adjust the position of the focusing lens 78, etc.

[0127] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. For example, in precision alignment, a non-contact method such as magnetic force or electrostatic force cannot be used, but various methods can be used as long as the pin 76 and the positioning block 70 are in contact with each other.

[0128] Moreover, an electric actuator (not shown) may be used as a moving mechanism for moving the above-mentioned positioning block 70, instead of the air cylinder 68. The electric actuator includes a motor as a power source and a moving body such as a rod or a slider.

[0129] A positioning block 70 is fixed to the moving body. The rotation of the output shaft of the motor is converted into linear movement of the moving body. Depending on the linear movement of the moving body, the positioning block 70 and one pin 76 are brought into contact or out of contact with each other.

[0130] In addition, instead of the stepping motor 66, air cylinder 68, positioning block 70 and multiple pins 76, the operator can manually operate a knob, handle, etc. to rotate the holder base 72 around the rotation axis 66a. [Explanation of symbols]

[0131] 2: laser processing device, 4: base, 6: base, 8: erection 10: chuck table, 10a: holding surface, 10b: clamp unit 11: Workpiece, 11a: Front side, 11b: Back side, 15: Tape 12: Y-axis direction movement mechanism, 14: Y-axis guide rail, 16: Y-axis direction movement table 17: Annular frame, 19: Workpiece unit 18: screw shaft, 20: drive source 22: X-axis direction movement mechanism, 24: X-axis guide rail, 26: X-axis direction movement table 28: screw shaft, 30: driving source, 32: support stand 34: Z-axis direction movement mechanism, 36: Z-axis guide rail, 38: Z-axis direction movement plate 40: driving source, 42: support 44: laser beam irradiation unit, 46: housing, 48: laser oscillator 50: head unit, 52: imaging unit, 54: touch panel 56: controller, 56a: processor, 56b: memory 58: Mirror, 60: Condenser lens unit 62: housing, 62a: top opening, 62b: bottom opening, 62c: circumferential direction, 62d: groove 64: Support plate, 64a: Claw portion, 64b: Top surface, 64c: Through hole, 64d: Bottom surface 64e: Straight end 66: stepping motor (rotation drive source), 66a: rotating shaft, 66a1: circumferential direction 68: Air cylinder (movement mechanism) 68a: L-shaped board, 68a1: Horizontal board, 68a2: Vertical board 70: Positioning block (second positioning member) 70a: base plate, 70a1: back surface, 70a2: front surface 70b: protrusion, 70b1: inclined surface, 70c: predetermined direction 72: holder base, 72a: top surface (outer surface) 72b: circumferential direction, 72c: bottom surface, 72d: through hole, 72e: screw hole 74: shaft holder, 74a: hole 76: Pin (first positioning member) 78, 78-1, 78-2, 78-3, 78-4: Condenser lenses 78a: lens, 78b: lens barrel, 78c: optical axis, 78d: first direction 78e: flange, 78e1: protrusion, 78e2: connection 80: holder, 80a: bottom surface 80a1: screw hole, 80a2: through hole, 80a3: holder fixing hole, 80b: top surface 82: Light path, L: Laser beam P, P1, P2, P3, P4: Focus point, θ: Obtuse angle

Claims

1. A laser processing device that irradiates a workpiece with a laser beam, A laser oscillator; a plurality of condenser lenses each including one or more lenses for condensing the laser beam emitted from the laser oscillator and a lens barrel in which the one or more lenses are fixed; a holder base that is rotatable around a predetermined rotation axis and that holds the plurality of condenser lenses arranged along a circumferential direction of the rotation axis; Equipped with A laser processing apparatus characterized in that, by rotating the holder base around the rotation axis, one of the plurality of focusing lenses is selectively positioned on the optical path of the laser beam irradiated to the workpiece.

2. the holder base includes a plurality of first positioning members provided on an outer surface of the holder base so as to have a one-to-one correspondence with the plurality of condenser lenses; a second positioning member that contacts any one of the plurality of first positioning members to determine a position of the one first positioning member in a circumferential direction of the rotation axis when the holder base is rotated around the rotation axis to selectively position one of the plurality of condenser lenses on the optical path of the laser beam; and a moving mechanism that, when determining a position of the one first positioning member in the circumferential direction of the rotation shaft, moves one or both of the one first positioning member and the second positioning member relatively in a direction different from the circumferential direction of the rotation shaft, thereby realizing a contact state in which the one first positioning member and the second positioning member are in contact with each other and a non-contact state in which the one first positioning member and the second positioning member are not in contact with each other; The laser processing apparatus according to claim 1 , further comprising:

3. a rotation drive source that rotates the holder base around the rotation axis; A controller for controlling the operation of the rotary drive source; Further comprising: The laser processing apparatus of claim 2, characterized in that the controller controls the operation of the rotational drive source to rotate the holder base and then operates the moving mechanism, thereby achieving the contact state in which the one first positioning member and the second positioning member are in contact.

4. A laser processing apparatus as described in any one of claims 1 to 3, characterized in that the positions of the one or more lenses in each barrel are predetermined so that the focal point of the laser beam focused by each of the multiple focusing lenses is located at a predetermined position in a first direction parallel to the optical axis of each focusing lens selectively arranged on the optical path of the laser beam.

5. each of the plurality of focusing lenses having the same numerical aperture, a different focal length, and a different entrance pupil diameter; 4. The laser processing apparatus according to claim 3, wherein the controller selectively positions the one of the plurality of focusing lenses on the optical path of the laser beam in response to a focal depth of the laser beam and a focusing density of the laser beam that are respectively determined according to processing conditions for the laser beam on the workpiece.

Images