Method for adapting a laser processing device

Abstract

Method for adapting a laser processing device (2), wherein the laser processing device (2) includes a clamping table (26) having a flat surface in an XY plane as a holding surface for holding a workpiece, a laser beam application unit (6) for applying a pulsed laser beam (LB) to the workpiece held on the clamping table (26), an image recording unit (8) for recording an image of the workpiece held on the clamping table (26), an X-axis movement mechanism (10) for moving the clamping table (26) and the image pickup unit (8) relative to each other in an X-axis direction, a Y-axis moving mechanism (12) for moving the chuck table (26) and the image pickup unit (8) relative to each other in a Y-axis direction perpendicular to the X-axis direction, and a control unit (14) having a coordinate recording section (56) and a correction value recording section (58), wherein the laser beam application unit (6) includes a laser oscillator (32) for oscillating a pulsed laser, an X-axis galvanometer scanner (34) for oscillating a pulsed laser beam (LB) emitted by the laser oscillator (32) in the X-axis direction, a Y-axis galvanometer scanner (36) for oscillating the pulsed laser beam (LB) emitted from the laser oscillator (32) in the Y-axis direction, and an fθ lens (38) for collecting the pulsed laser beam (LB) swept in the X-axis direction and the Y-axis direction on the workpiece held on the clamping table (26), the method comprising: a holding step for holding the workpiece on the clamping table (26); a coordinate recording step for recording in the coordinate recording section (56) X-coordinates and Y-coordinates of positions at which the pulsed laser beam (LB) is to be applied to the workpiece held on the chuck table (26); a machining step of controlling the X-axis galvanometer scanner (34) and the Y-axis galvanometer scanner (36) on the basis of the X-coordinates and the Y-coordinates recorded in the coordinate recording section to apply the pulsed laser beam (LB) to the workpiece held on the chuck table (26), thereby machining the workpiece; a machining mark image pickup step for operating the X-axis moving mechanism (10) and the Y-axis moving mechanism (12) on the basis of the X-coordinates and Y-coordinates picked up in the coordinate pickup section to position the image pickup unit (8) in alignment with the machining marks on the workpiece held on the chuck table (26) and cause the image pickup unit (8) to pick up an image of the machining marks; and a correction value recording step for detecting offsets between X-coordinates and Y-coordinates of the machining marks whose image was captured in the image capturing step for a machining mark and the X-coordinates and Y-coordinates captured in the coordinate recording section (56), and recording a correction value in the correction value recording section (56), wherein the machining mark image pickup step includes a step of positioning the image pickup unit (8) spirally toward an outer periphery of the workpiece from a machining mark corresponding to a center of the fθ lens (38) as a starting point.

Description

BACKGROUND OF THE INVENTIONTechnical field

[0001] The present invention relates to a method for adjusting the position at which a pulsed laser beam is applied to a workpiece in a laser processing apparatus. Description of the state of the art

[0002] Wafers having multiple devices such as integrated circuits (ICs) and large-scale integration circuits (LSI) formed in respective regions on one surface side divided by multiple planned dividing lines are divided into individual device chips by a laser processing apparatus, and the divided device chips are used in electronic equipment such as mobile phones and personal computers.

[0003] The laser processing apparatus includes a chuck table having a flat surface in an XY plane as a holding surface for holding a workpiece, i.e., a wafer thereon, a laser beam application unit for applying a pulsed laser beam to the workpiece held on the chuck table, an image pickup unit for picking up an image of the workpiece held on the chuck table, an X-axis moving mechanism for moving the chuck table and the image pickup unit relative to each other in the X-axis direction, a Y-axis moving mechanism for moving the chuck table and the image pickup unit relative to each other in the Y-axis direction perpendicular to the X-axis direction, and a control unit. The laser processing apparatus is capable of very finely processing the wafer.

[0004] A laser machining apparatus that machines a workpiece by projecting and applying a laser beam to multiple locations on the workpiece includes a laser oscillator for oscillating a pulsed laser beam, an X-axis galvanometer scanner for oscillating a pulsed laser beam emitted from the laser oscillator in the X-axis direction, a Y-axis galvanometer scanner for oscillating the pulsed laser beam emitted from the laser oscillator in the Y-axis direction, and an fθ lens for converging the pulsed laser beam oscillated in the X-axis and Y-axis directions onto the workpiece held on the chuck table (see, for example, JP 2008-264805A). The laser machining apparatus can be used to apply the pulsed laser beam to multiple electrodes on the devices on a wafer to form through-holes in the electrodes.DE 44 37 284 A1 relates to a method for calibrating a control system for deflecting a laser beam. US 2013 / 0 186 871 A1 relates to a processing device that includes mirrors for reflecting a laser beam. PRESENTATION OF THE INVENTION

[0005] However, the fθ lens has a problem in that the laser beam, while passing through the fθ lens, tends to be progressively more deformed from the center to the outer periphery of the lens, and it is problematic in that, even if the X-axis galvanometer scanner and the Y-axis galvanometer scanner are precisely controlled, the through holes formed in the outer peripheral region of the wafer are likely to be offset from the electrodes.

[0006] It is therefore an object of the present invention to provide a method for adapting a laser processing apparatus to process a workpiece with a pulsed laser beam precisely at positions where the pulsed laser beam is to be applied to electrodes or the like on components on the workpiece.

[0007] According to one aspect of the present invention, a method for adapting a laser processing apparatus is provided. The laser processing apparatus includes a chuck table having a flat surface in an XY plane as a holding surface for holding a workpiece thereon, a laser beam application unit for applying a pulsed laser beam to the workpiece held on the chuck table, an image pickup unit for capturing an image of the workpiece held on the chuck table, an X-axis moving mechanism for moving the chuck table and the image pickup unit relative to each other in an X-axis direction, a Y-axis moving mechanism for moving the chuck table and the image pickup unit relative to each other in a Y-axis direction perpendicular to the X-axis direction, and a control unit.which has a coordinate recording section and a correction value recording section. The laser beam application unit includes a laser oscillator for oscillating a pulsed laser, an X-axis galvanometer scanner for oscillating a pulsed laser beam emitted from the laser oscillator in the X-axis direction, a Y-axis galvanometer scanner for oscillating the pulsed laser beam emitted from the laser oscillator in the Y-axis direction, and an fθ lens for converging the pulsed laser beam oscillated in the X-axis and Y-axis directions onto the workpiece held on the chuck table. The method includes a holding step for holding the workpiece on the chuck table, a coordinate recording step for recording, in the coordinate recording section, X-coordinates and Y-coordinates of positions at which the pulsed laser beam is applied to the workpiece,which is held on the chuck table, a machining step of controlling the X-axis galvanometer scanner and the Y-axis galvanometer scanner based on the X-coordinates and the Y-coordinates recorded in the coordinate recording section to apply the pulsed laser beam to the workpiece held on the chuck table, thereby machining the workpiece; a machining mark image capturing step of operating the X-axis moving mechanism and the Y-axis moving mechanism based on the X-coordinates and the Y-coordinates recorded in the coordinate recording section to position the image capturing unit in alignment with the machining marks on the workpiece held on the chuck table, and causing the image capturing unit to capture an image of the machining marks,and a correction value recording step for detecting offsets between X-coordinates and Y-coordinates of the processed marks whose image was captured in the image capturing step for a processing mark and the X-coordinates and Y-coordinates captured in the coordinate recording section, and recording correction values ​​in the correction value recording section.

[0008] The image pickup step for a machining mark includes the step of positioning the image pickup unit spirally downward to the outer circumference of the workpiece from the machined mark corresponding to the center of the fθ lens as a starting point.

[0009] According to the present invention, the coordinates of the target positions where the pulsed laser beam is to be applied are corrected from the coordinates obtained in the coordinate acquisition section based on the coordinates of the machining marks actually produced on the workpiece. Consequently, the workpiece can be accurately machined with the laser beam at positions such as component electrodes on the workpieces where the laser beam is to be applied.

[0010] The above and other objects, features and advantages of the present invention and the mode for carrying them out will become more apparent and the invention itself will be best understood by studying the following description and the appended claims with reference to the attached drawings which show preferred embodiments of the invention. SHORT DESCRIPTION OF THE CHARACTERS Fig. 1 is a perspective view of a laser processing apparatus adjusted by an adjusting method according to an embodiment of the present invention; Fig. 2 is a block diagram of some components of the laser processing device shown in Fig. 1 is shown; Fig. 3A is a perspective view of a wafer with components formed thereon to be processed by the laser processing apparatus; Fig. 3B is a perspective view of a dummy wafer; Fig. 4 is a table of X coordinates and Y coordinates recorded in the coordinate recording section of a control unit of the laser processing apparatus; Fig. 5 is a schematic diagram of some X-coordinates and Y-coordinates of a plurality of machining marks whose images were captured by an image capturing unit in a machining mark image capturing section, and some of the X-coordinates and Y-coordinates captured in the coordinate capturing section; and Fig. 6 is a table of X coordinates and Y coordinates of machining marks recorded in the correction value recording section of the control unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0011] A method for adjusting a laser processing device according to a preferred embodiment of the present invention will be described below with reference to the accompanying figures. The method for adjusting a laser processing device is also referred to as an adjustment method. Fig. 1 is a perspective view of a laser processing apparatus to be adjusted by the adjustment method according to the present embodiment. As shown in Fig. 1, the laser processing device, designated by 2, includes a holding unit 4 having a flat surface in an XY plane as a holding surface for holding a workpiece, a laser beam application unit 6 for applying a pulsed laser beam to the workpiece held on the holding unit 4, an image pickup unit 8 for picking up an image of the workpiece held on the holding unit 4, an X-axis moving mechanism 10 for moving the holding unit 4 and the image pickup unit 8 relative to each other in an X-axis direction, a Y-axis moving mechanism 12 for moving the holding unit 4 and the image pickup unit 8 relative to each other in a Y-axis direction, and a control unit 14 for controlling an operation of the laser processing device 2. The X-axis direction represents a direction indicated by an arrow X in Fig. 1 and a direction opposite thereto and the Y-axis direction represents a direction indicated by an arrow Y in Fig. 1, and an opposite direction, the Y-axis direction, is perpendicular to the X-axis direction. The XY plane is defined by the X-axis direction and the Y-axis direction and is essentially horizontal.

[0012] The holding unit 4 includes an X-axis movable plate 18 movably mounted on a base 16 for movement in the X-axis direction, a Y-axis movable plate 20 movably mounted on the X-axis movable plate 18 for movement in the Y-axis direction, a support column 22 fixedly attached to an upper surface of the Y-axis movable plate 20, and a cover plate 24 fixed to an upper end of the support column 22. The cover plate 24 has an elongated hole 24a formed therein and extending longitudinally in the Y-axis direction. The holding unit 4 also includes a chuck table 26 rotatably mounted on the upper end of the support column 22 and extending upward through the elongated hole 24a. The clamping table 26 is rotatably housed in the support column 22 by a rotating means such as an electric motor, which is not shown.

[0013] A circular suction chuck 28, formed of a porous material and connected to a suction means (not shown), is disposed on an upper surface of the chuck table 26. The suction chuck 28 has an upper surface located in the XY plane. The chuck table 26, when the suction means is actuated, generates suction forces acting on the upper surface of the suction chuck 28 to thereby hold the workpiece placed thereon under suction. In the holding unit 4, therefore, the upper surface of the suction chuck 28 lies in the XY plane for holding the workpiece. A plurality of circumferentially spaced clamps 30 are arranged around the outer peripheral edge of the chuck table 26 for clamping the workpiece to the chuck table 26.

[0014] As in Fig. 2, the laser beam application unit 6 includes a laser oscillator 32 for oscillating a pulsed laser, an X-axis galvanometer scanner 34 for oscillating a pulsed laser beam LB emitted from the laser oscillator 32 in the X-axis direction, a Y-axis galvanometer scanner 36 for oscillating the pulsed laser beam LB emitted from the laser oscillator 32 in the Y-axis direction, and an fθ lens 38 for converging the pulsed laser beam LB oscillated in the X-axis direction and the Y-axis direction onto the workpiece held on the holding unit 4.

[0015] The X-axis galvanometer scanner 34 and the Y-axis galvanometer scanner 36 may each have a known structure, including a mirror (not shown) and an angle adjustment actuator (not shown) for adjusting the angle at which the mirror is positioned. The fθ lens 38 applies the pulsed laser beam LB, which has been swept in the X-axis and Y-axis directions, perpendicularly to the upper surface of the chuck table 26.

[0016] As in Fig. As shown in Figure 1, the laser beam application unit 6 according to the present embodiment includes a housing 40 including a vertical portion extending upward from an upper surface of the base 16 and a horizontal portion extending substantially horizontally from an upper portion of the vertical portion. The housing 40 houses the laser oscillator 32, the X-axis galvanometer scanner 34, the Y-axis galvanometer scanner 36, and a mirror 42 (see Fig. 2) to reflect the pulsed laser beam LB swept in the X-axis direction and the Y-axis direction to the fθ lens 38. As shown in Fig. 1, an fθ lens housing 44, which houses the fθ lens 38 therein, is arranged on a lower surface of the distal end of the horizontal portion of the housing 40.

[0017] The pulsed laser beam LB emitted from the laser oscillator 32 of the laser beam application unit 6 is oscillated in the X-axis direction and the Y-axis direction by the X-axis galvanometer scanner 34 and the Y-axis galvanometer scanner 36, reflected by the mirror 42 to the fθ lens 38, collected by the fθ lens 38, and then output and applied to multiple locations on the workpiece held on the holding unit 4.

[0018] As in Fig. As shown in Figure 1, the image pickup unit 8 is fixed to the lower surface of the distal end of the horizontal portion of the housing 40 at a position spaced apart from the fθ lens housing 44 in the X-axis direction. The image pickup unit 8 includes an image pickup device such as a charge-coupled device (CCD) for capturing an image of the workpiece with a visible light beam. The image pickup unit 8 is electrically connected to a display unit 46 disposed on an upper surface of the distal end of the horizontal portion of the housing 40 so that the image of the workpiece captured by the image pickup unit 8 can be displayed on the display unit 46.

[0019] As in Fig. 1, the X-axis moving mechanism 10 includes a ball screw 48 extending in the X-axis direction along the upper surface of the base 16, and an electric motor 50 for rotating the ball screw 48 about its central axis. The ball screw 48 is screwed by a nut (not shown) that is coupled to the X-axis moving plate 18. When the electric motor 50 is energized, the ball screw 48 converts the rotational motion of the electric motor 50 into linear motion and transmits the linear motion to the X-axis moving plate 18, thereby moving the X-axis moving plate along the guide rails 16a on the base 16 relative to the image pickup unit 8 in the X-axis direction.

[0020] The Y-axis moving mechanism 12 includes a ball screw 52 extending in the Y-axis direction along an upper surface of the X-axis moving plate 18, and an electric motor 54 for rotating the ball screw 52 about its central axis. The ball screw 52 is screwed by a nut (not shown) that is coupled to the Y-axis moving plate 20. When the electric motor 54 is energized, the ball screw 52 converts the rotational motion of the electric motor 54 into linear motion and transmits the linear motion to the Y-axis moving plate 20, thereby moving the Y-axis moving plate 20 along the guide rails 18a on the X-axis moving plate 18 relative to the image pickup unit 8 in the Y-axis direction.

[0021] The control unit 14 is configured as a computer including a central processing unit (CPU), not shown, for performing an arithmetic processing operation according to a control program, a read-only memory (ROM), not shown, for storing the control programs, etc., and a read / write memory (RAM), not shown, for storing the results of the arithmetic processing operation, etc. As shown in Fig. 1, the working memory implements a coordinate acquisition section 56 for acquisition of the X-coordinates and the Y-coordinates of positions at which the pulsed laser beam LB is to be applied to the workpiece held on the holding unit 4, and a correction value acquisition section 58 for acquisition of correction values ​​based on an offset of the X-coordinates and the Y-coordinates of the machining marks, the image of which was acquired by the image acquisition unit 8, from the X-coordinates and Y-coordinates acquired in the coordinate acquisition section 56.

[0022] The control unit 14, which controls the entire operation of the laser processing device 2, controls the laser beam application unit 6 to output and apply the pulsed laser beam LB to multiple locations on the workpiece held on the holding unit 4, based on the X-coordinates and Y-coordinates recorded in the coordinate recording section 56, for example. Furthermore, the control unit 14 controls the X-axis moving mechanism 10 and the Y-axis moving mechanism 12 to position the image pickup unit 8 in alignment with the machining marks on the workpiece held on the holding unit 4, allowing the image pickup unit 8 to capture an image of the machining marks based on the X-coordinates and Y-coordinates recorded in the coordinate recording section 56.

[0023] Fig. 3A perspectively illustrates a wafer 60 shaped as a circular plate as an example of the workpiece. The wafer 60 may be formed of silicon or the like, for example. The wafer 60 has a plurality of rectangular regions on one surface side 60a divided by a grid of planned dividing lines 62, and a plurality of components 64, such as ICs and LSI circuits, formed in the respective rectangular regions. Each of the components 64 has a plurality of electrodes 66. The wafer 60 has a notch (recess) 68 formed in a peripheral edge as an indicator of the crystal orientation of the wafer 60. The wafer 60 according to the present embodiment has a rear side 60b fixed to an adhesive tape 72, the peripheral edge portion of which is secured by an annular frame 70.

[0024] Fig. 3B perspectively illustrates a dummy wafer 74 shaped as a circular plate as another example of the workpiece. The dummy wafer 74, supported on an annular frame 70 by an adhesive tape 72, has no planned parting lines and components. The dummy wafer 74 has dimensions, such as diameter and thickness, identical to those of the wafer 60 and is formed of a material identical to that of the wafer 60. The dummy wafer 74 according to the present embodiment has a notch (recess) 76 defined in a circumferential edge as an indicator of the crystal orientation of the dummy wafer 74. The notch 76 has the same shape as the notch 68 of the wafer 60.

[0025] The method for adjusting the laser processing apparatus 2, that is, adjusting the position at which the pulsed laser beam LB is applied to the workpiece, that is, the wafer 60, will be described below. In the adjusting method according to the present embodiment, first, a holding step for holding the workpiece on the holding unit 4 is performed. In the holding step, the dummy wafer 74 supported on the annular frame 70 by the adhesive tape 72 is placed on the suction chuck 28 on the upper surface of the chuck table 26 of the holding unit 4. Then, the suction means connected to the suction chuck 28 is actuated to apply suction to the upper surface of the suction chuck 28, thereby holding the dummy wafer 74 on the suction chuck 28 under suction.

[0026] Furthermore, the clamps 30 are rotated to clamp the annular frame 70.

[0027] After the holding step is performed, a coordinate acquisition step is performed to acquire, in the coordinate acquisition section 56, the X-coordinates and Y-coordinates of the positions where the pulsed laser beam LB is to be applied to the workpiece held on the holding unit 4. The X-coordinates and Y-coordinates to be acquired in the coordinate acquisition section 56 in the coordinate acquisition step represent the X-coordinates and Y-coordinates of the plurality of positions where the workpiece is to be processed by the pulsed laser beam LB, for example, the X-coordinates and Y-coordinates indicating the positions of the electrodes 66 in the wafer 60. Fig. As an example of the X-coordinates and Y-coordinates indicating the positions of the electrode 66, FIG. 4 illustrates the X-coordinates and Y-coordinates (Xn, Yn) of a total of 2601 (51 × 51) electrodes 66 arranged in a matrix of 51 electrodes spaced apart in the X-axis direction and 51 electrodes spaced apart in the Y-axis direction. The X-coordinates and Y-coordinates to be recorded in the coordinate recording section 56 can be set in various ways using the notch 68 of the wafer 60 or the like as a reference.

[0028] After the coordinate acquisition step is performed, a machining step is performed to control the X-axis galvanometer scanner 34 and the Y-axis galvanometer scanner 36 based on the X-coordinates and the Y-coordinates acquired in the coordinate acquisition section 56 to apply the pulsed laser beam LB to the workpiece held on the holding unit 4, thereby machining the workpiece.

[0029] In the machining step, the X-axis moving mechanism 10 and the Y-axis moving mechanism 12 move the chuck table 26 to position the dummy wafer 74 held on the holding unit 4 and below the fθ lens housing 44, and the electric motor for the chuck table 26 rotates the chuck table 26 to adjust the orientation of the dummy wafer 74 to a predetermined orientation. The coordinates of the target positions to which the pulsed laser beam LB is to be applied are set to the X-coordinates and the Y-coordinates recorded in the coordinate recording section 56, and then the pulsed laser beam LB is emitted and applied to the dummy wafer 74 to machine a plurality of locations on the dummy wafer 74 spaced apart in the X-axis direction and the Y-axis direction, leaving machining marks at the locations.In the processing step according to the present embodiment, a total of 2601 (51 × 51) processing marks are formed on the dummy wafer 74 based on the X coordinates and Y coordinates (Xn, Yn) indicating the positions of the electrodes 66.

[0030] After the machining step is performed, a machining mark image pickup step is performed to move the X-axis moving mechanism 10 and the Y-axis moving mechanism 12 based on the X-coordinates and the Y-coordinates acquired in the coordinate pickup section 56, to position the image pickup unit 8 in alignment with the machining marks on the workpiece held on the holding unit 4, and to cause the image pickup unit 8 to capture an image of the machining marks.

[0031] Fig. 5 schematically illustrates some of the X coordinates and Y coordinates of the plurality of machining marks whose images were captured by the image pickup unit 8.

[0032] More precisely, the places marked by a symbol × in Fig. 5, the positions of the processing marks formed on the dummy wafer 74 by the pulsed laser beam LB applied after the coordinates of the target positions to which the pulsed laser beam LB should be applied were set to the X-coordinates and the Y-coordinates (Xn, Yn) recorded in the coordinate recording section 56. In addition, Fig. 5 the locations indicated by the symbol × are accompanied by X coordinates and Y coordinates (αn, βn), and the locations representing some of the X coordinates and Y coordinates recorded in the coordinate recording section 56 are indicated by a symbol · and accompanied by X coordinates and Y coordinates (Xn, Yn).

[0033] In the image pickup step for a processing mark, it is preferable that the image pickup unit 8 is spirally moved to the outer periphery of the dummy wafer 74 from the processing mark (α 1300 , β 1300) corresponding to the center of the fθ lens 38 as a starting point. In this way, the image pickup unit 8 can reliably pick up each machining mark even in the case where the field of view of the image pickup unit 8 is smaller than the offset between the coordinates (αn, βn) of the machining mark and the coordinates (Xn, Yn) picked up in the coordinate picking section 56. In the example shown in Fig. 5, the coordinates (α 1300 , β 1300 ) of the machining mark corresponding to the center of the fθ lens 38 with the coordinates (X 1300 , Y 1300 ) recorded in the coordinate recording section 56, whereas the coordinates of the machining marks that do not match the coordinates (α 1300 , β 1300) are offset from the coordinates recorded in the coordinate recording section 56, ie the coordinates of the target positions to which the pulsed laser beam LB is to be applied.

[0034] After the machining mark image capturing step is performed, a correction value capturing step is performed to detect offsets between X and Y coordinates (αn, βn) of the machining marks whose image was captured in the machining mark image capturing step and the X and Y coordinates (Xn, Yn) captured in the coordinate capturing section 56 of the control unit 14, and to capture correction values ​​in the correction value capturing section 58.

[0035] In the correction value acquisition step, the coordinates (αn, βn) of the machining marks are determined from the image of the machining marks, the image of which was acquired in the image acquisition step for a machining mark (see Fig.6). Then, an offset, i.e., offset in the X-axis direction and in the Y-axis direction, between the coordinates (αn, βn) of the machining marks and the coordinates (Xn, Yn) recorded in the coordinate recording section 56 is detected. Then, correction values ​​for correcting the coordinates of the target positions to which the pulsed laser beam LB is to be applied are calculated from the coordinates (Xn, Yn) recorded in the coordinate recording section 56, based on the detected offset. The calculated correction values ​​are recorded in the correction value recording section 58 of the control unit 14.Further, the coordinates of the target positions to which the pulsed laser beam LB is to be applied are corrected from the coordinates (Xn, Yn) recorded in the coordinate recording section 56 using the calculated correction values, and the corrected coordinates of the target positions to which the pulsed laser beam LB is to be applied are recorded in the correction value recording section 58.

[0036] In the correction value acquisition step, in order to deal with various machining conditions, the correction values ​​referred to above may be replaced with a function, and such a function may be acquired in the correction value acquisition section 58, and then, using the function that has replaced the correction values, the coordinates of the target positions to which the pulsed laser beam LB is to be applied may be corrected from the coordinates (Xn, Yn) acquired in the coordinate acquisition section 56.Furthermore, an area to which the pulsed laser beam LB is applied in the laser processing apparatus 2 by the X-axis galvanometer scanner 34 and the Y-axis galvanometer scanner 36 as they are operated can be divided into a plurality of areas, and a function for correcting the coordinates of the target positions to which the pulsed laser beam LB is to be applied can be calculated from the coordinates (Xn, Yn) acquired in the coordinate acquisition section 56 with respect to each of the divided areas. When each of the areas is machined by the pulsed laser beam LB, the coordinates of the target positions to which the laser beam LB is to be applied can be corrected from the coordinates (Xn, Yn) acquired in the coordinate acquisition section 56 according to the function calculated with respect to the area.

[0037] After the correction value acquisition step is performed, the suction means connected to the suction chuck 28 of the holding unit 4 is deactivated to release the dummy wafer 74 from the suction chuck 28, and the clamps 30 are reversed to release the annular frame 70. Then, the dummy wafer 74 used as the workpiece for calculating the correction value is removed from the holding unit 4. Thereafter, the wafer 60, as a workpiece to be machined with the pulsed laser beam LB (that is, a workpiece on which through-holes are to be formed in the respective electrodes 66 according to the present embodiment), is held on the holding unit 4 under suction.The X-axis galvanometer scanner 34 and the Y-axis galvanometer scanner 36 are controlled to emit the pulsed laser beam LB and apply it to the wafer 60 based on the corrected coordinates at the target positions where the pulsed laser beam LB is to be applied, thereby forming through holes in the electrodes 66 on the wafer 60.

[0038] In the method for adjusting the laser processing apparatus 2 according to the present embodiment, the coordinates of the target positions to which the pulsed laser beam LB is to be applied are corrected from the coordinates (Xn, Yn) recorded in the coordinate recording section 56 based on the X and Y coordinates (αn, βn) of the processing marks actually formed on the dummy wafer 74. Consequently, the pulsed laser beam LB can be applied to the electrodes 66 on the devices 64 on the wafer 60 to form through holes accurately at the respective electrodes 66.

Claims

[1] Method for adapting a laser processing device (2), wherein the laser processing device (2) includes a clamping table (26) having a flat surface in an XY plane as a holding surface for holding a workpiece, a laser beam application unit (6) for applying a pulsed laser beam (LB) to the workpiece held on the clamping table (26), an image recording unit (8) for recording an image of the workpiece held on the clamping table (26), an X-axis movement mechanism (10) for moving the clamping table (26) and the image pickup unit (8) relative to each other in an X-axis direction, a Y-axis moving mechanism (12) for moving the chuck table (26) and the image pickup unit (8) relative to each other in a Y-axis direction perpendicular to the X-axis direction, and a control unit (14) having a coordinate recording section (56) and a correction value recording section (58), wherein the laser beam application unit (6) includes a laser oscillator (32) for oscillating a pulsed laser, an X-axis galvanometer scanner (34) for oscillating a pulsed laser beam (LB) emitted by the laser oscillator (32) in the X-axis direction, a Y-axis galvanometer scanner (36) for oscillating the pulsed laser beam (LB) emitted from the laser oscillator (32) in the Y-axis direction, and an fθ lens (38) for collecting the pulsed laser beam (LB) swept in the X-axis direction and the Y-axis direction onto the workpiece held on the chuck table (26), the method comprising: a holding step for holding the workpiece on the clamping table (26); a coordinate recording step for recording in the coordinate recording section (56) X-coordinates and Y-coordinates of positions at which the pulsed laser beam (LB) is to be applied to the workpiece held on the chuck table (26); a machining step of controlling the X-axis galvanometer scanner (34) and the Y-axis galvanometer scanner (36) on the basis of the X-coordinates and the Y-coordinates recorded in the coordinate recording section to apply the pulsed laser beam (LB) to the workpiece held on the chuck table (26), thereby machining the workpiece; a machining mark image pickup step for operating the X-axis moving mechanism (10) and the Y-axis moving mechanism (12) on the basis of the X-coordinates and Y-coordinates picked up in the coordinate pickup section to position the image pickup unit (8) in alignment with the machining marks on the workpiece held on the chuck table (26) and cause the image pickup unit (8) to pick up an image of the machining marks; and a correction value recording step for detecting offsets between X-coordinates and Y-coordinates of the machining marks whose image was captured in the image capturing step for a machining mark and the X-coordinates and Y-coordinates captured in the coordinate recording section (56), and recording a correction value in the correction value recording section (56), wherein the machining mark image pickup step includes a step of positioning the image pickup unit (8) spirally toward an outer periphery of the workpiece from a machining mark corresponding to a center of the fθ lens (38) as a starting point.

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