Plate-like object processing method

Abstract

To provide a plate-like object processing method capable of precisely performing laser processing while adjusting an index feed amount even in a case where a planned dividing line or a device serving as a mark does not exist on a plate-like object.SOLUTION: A plate-like object processing method includes: a preparation step of preparing a laser processing apparatus; a holding step of holding a plate-like object on a chuck table; a setting step of imaging the plate-like object held on the chuck table by imaging means, setting a region to be processed, and storing coordinates; a mark forming step of forming marks P1 to P16 corresponding to the region to be processed by operating X-axis feeding means, Y-axis feeding means, and laser irradiation means 6 based on a coordinate; and a processing step of imaging the marks P1 to P16 formed on the plate-like object by the imaging means and processing the plate-like object into a chip 12 by applying a laser beam LB2 to a region to be processed by operating the X-axis feeding means, the Y-axis feeding means, and the laser irradiation means.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for processing a plate-like object into a plurality of chips. [Background technology]

[0002] Wafers with multiple devices such as ICs and LSIs formed on their surface along planned dividing lines are then separated into individual device chips using dicing equipment and laser processing equipment, and are used in electrical devices such as mobile phones and personal computers.

[0003] The laser processing apparatus includes a chuck table that holds a wafer, a laser irradiation means that irradiates a laser beam along a planned dividing line of the wafer held on the chuck table to form a starting point for dividing, an imaging means that images the wafer held on the chuck table, an X-axis feed means that feeds the chuck table and the laser irradiation means in the X-axis direction for processing, and a Y-axis feed means that feeds the chuck table and the laser irradiation means in the Y-axis direction that is perpendicular to the X-axis direction for processing, and is capable of processing the wafer into individual device chips (see, for example, Patent Document 1).

[0004] Furthermore, when a laser beam is irradiated onto the planned dividing line, the planned dividing line swells slightly, and therefore, when index feed is performed at the set intervals of the planned dividing line, the swell accumulates, and the laser beam is irradiated onto an area outside the planned dividing line, causing damage to the device. To address this problem, the applicant has proposed a processing method in which the position of the planned dividing line is directly confirmed periodically or at any timing, or the position of a feature point on the device is confirmed, and laser processing is performed while adjusting the index feed amount (see Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-000752 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-082296 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when manufacturing optical components, device covers, etc. by dividing a plate-like material such as glass or sapphire into chips, there are no dividing lines or devices on the plate-like material to serve as markers, so it is not possible to perform precise laser processing while checking the dividing lines or characteristic points of the devices and adjusting the index feed amount, which results in the problem of producing products with irregular chip sizes and shapes.

[0007] The present invention has been made in consideration of the above facts, and its main technical object is to provide a method for processing plate-like objects that can perform precise laser processing while adjusting the index feed amount, even if there are no dividing lines or devices to serve as markers on the plate-like object. [Means for solving the problem]

[0008] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a method for processing a plate-like object into a plurality of chips, which includes providing a laser processing apparatus including a rotatable chuck table for holding the plate-like object, laser irradiation means for irradiating the plate-like object held on the chuck table with a laser beam to form starting points for division, imaging means for imaging the plate-like object held on the chuck table, X-axis feed means for feeding the chuck table and the laser irradiation means for processing in the X-axis direction, Y-axis feed means for feeding the chuck table and the laser irradiation means for processing in the Y-axis direction perpendicular to the X-axis direction, and control means. a holding step of holding a plate-like object on the chuck table; a setting step of imaging the plate-like object held on the chuck table with the imaging means, setting an area to be processed, and storing coordinates; a mark forming step of operating the X-axis feed means, the Y-axis feed means, and the laser irradiation means based on the coordinates to form a mark corresponding to the area to be processed; and a processing step of imaging the mark formed on the plate-like object by the imaging means, operating the X-axis feed means, the Y-axis feed means, and the laser irradiation means to irradiate the area to be processed with a laser beam, thereby processing the plate-like object into chips.

[0009] The wavelength of the laser beam irradiated by the laser irradiation means is preferably transparent to the plate-like object, and in the mark forming step and the processing step, the focal point of the laser beam is preferably positioned inside the plate-like object to form a modified layer. Also, it is preferable that the output of the laser beam irradiated in the mark forming step is set smaller than the output of the laser beam irradiated in the processing step. Furthermore, in the mark forming step, it is preferable that the mark is formed in an area where no chip is to be formed.

[0010] After the processing step, it is preferable to apply an external force to the plate-like object to divide it into individual chips. Furthermore, it is preferable that the shape of the chip is a pentagon with one corner missing from a rectangle, and that the mark is formed in the region of the missing corner in the mark forming step. [Effects of the Invention]

[0011] The method for processing a plate-like object of the present invention includes a preparation step of preparing a laser processing apparatus including a rotatable chuck table that holds the plate-like object, a laser irradiation means that irradiates the plate-like object held on the chuck table with a laser beam to form a starting point for division, an imaging means that images the plate-like object held on the chuck table, an X-axis feed means that feeds the chuck table and the laser irradiation means for processing in the X-axis direction, a Y-axis feed means that feeds the chuck table and the laser irradiation means for processing in the Y-axis direction perpendicular to the X-axis direction, and a control means, a holding step of holding the plate-like object on the chuck table, and a setting step of imaging the plate-like object held on the chuck table with the imaging means, setting an area to be processed, and storing coordinates. and a processing step in which the mark formed on the plate-like object is captured by the imaging means and the X-axis feed means, Y-axis feed means, and laser irradiation means are activated to irradiate the area to be processed with a laser beam, thereby processing the plate-like object into chips. Therefore, when a plate-like object having no planned division lines or devices is divided into chips to manufacture optical components, device covers, etc., it is possible to perform laser processing while adjusting the index feed amount using the marks formed in the mark forming step, thereby eliminating the problem of producing products with irregular chip sizes and shapes. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an overall perspective view of a laser processing device used in a plate-shaped object processing method according to an embodiment of the present invention. [Figure 2] 2 is a perspective view of a sapphire substrate to be processed by the laser processing apparatus shown in FIG. 1. FIG. [Figure 3] 2 is a conceptual diagram showing the XY coordinates of planned dividing lines stored in the control means of the laser processing apparatus shown in FIG. 1. FIG. [Figure 4] FIG. 10 is a conceptual diagram illustrating an embodiment of a setting process. [Figure 5]10 is a conceptual diagram showing information on the XY coordinates of the planned division line and marks set in the setting step. FIG. [Figure 6] FIG. 1(a) is a perspective view showing an embodiment of the mark forming step, and FIG. 1(b) is a partially enlarged cross-sectional view showing an embodiment of the mark formed by the mark forming step shown in FIG. [Figure 7] FIG. 1A is a perspective view showing an embodiment of a processing step, and FIG. 1B is a perspective view showing a state in which a modified layer has been formed over the entire area of ​​the sapphire substrate by the processing step shown in FIG. [Figure 8] (a) A conceptual diagram showing the planned division line using a pentagonal chip with one corner of a rectangle missing, and the XY coordinate information with a mark set at the missing corner, using the setting process of another embodiment; (b) A conceptual diagram showing an enlarged view of part A in (a). DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for processing a plate-like object according to the present invention will be described in detail below with reference to the accompanying drawings.

[0014] 1 shows a laser processing apparatus 1 suitable for carrying out the plate-like object processing method of this embodiment. The laser processing apparatus 1 includes a rotatable chuck table 35 that holds the plate-like object to be processed, a laser irradiation means 6 that irradiates the plate-like object held on the chuck table 35 with a laser beam to form a starting point for division, an imaging means 7 that images the plate-like object held on the chuck table 35, an X-axis feed means 4a that feeds the chuck table 35 and the laser irradiation means 6 in the X-axis direction for processing, a Y-axis feed means 4b that feeds the chuck table 35 and the laser irradiation means 6 in the Y-axis direction perpendicular to the X-axis direction for processing, and a control means 100.

[0015] The plate-like object processed by the processing method of this embodiment is, for example, a substantially disk-shaped sapphire substrate 10 as shown in Fig. 2. The illustrated sapphire substrate 10 has a diameter of 6 inches and a thickness of 150 µm, and no devices or planned division lines are formed on the surface 10a. The sapphire substrate 10 is positioned at the center of an opening Fa of an annular frame F that can accommodate the sapphire substrate 10, and is supported by the frame F via adhesive tape T.

[0016] The sapphire substrate 10 has a linear orientation flat 10b formed thereon, which indicates the crystal orientation. When the substrate is supported by the frame F, the flat is positioned and supported so as to be parallel to the linear portion Fd on the side of the frame F where the notches Fb and Fc are formed.

[0017] As shown in Fig. 3, the control means 100 of the laser processing apparatus 1 stores coordinate information of division lines 14, which serve as starting points for dividing the sapphire substrate 10 into individual chips 12. However, as described above, no visible devices or division lines are formed on the surface 10a of the sapphire substrate 10. Therefore, the sapphire substrate 10 is processed by the method for processing a plate-like object according to the present invention, which will be described below.

[0018] (preparation process) When processing a sapphire substrate 10 by the plate-like object processing method of this embodiment, the above-mentioned laser processing apparatus 1 is prepared, that is, the laser processing apparatus 1 is configured to include the rotatable chuck table 35 that holds the sapphire substrate 10, laser irradiation means 6 that irradiates the sapphire substrate 10 held on the chuck table 35 with a laser beam to form a starting point for division, imaging means 7 that images the sapphire substrate 10 held on the chuck table 35, X-axis feed means 4a that feeds the chuck table 35 and the laser irradiation means 6 in the X-axis direction for processing, Y-axis feed means 4b that feeds the chuck table 35 and the laser irradiation means 6 in the Y-axis direction perpendicular to the X-axis direction for processing, and control means 100.

[0019] As shown in FIG. 1, the above-described configuration of the laser processing device 1 is disposed on a base 2, and in addition to the above-described configuration, the base 2 is provided with a frame 5 consisting of a vertical wall portion 5a erected on the side of the X-axis feed means 4a and the Y-axis feed means 4b constituting the processing feed means 4 and a horizontal wall portion 5b extending horizontally from the upper end of the vertical wall portion 5a, and a display means 8.

[0020] The holding means 3, which includes a chuck table 35, is a means for holding the sapphire substrate 10 using an XY plane, defined by X and Y coordinates, as a holding surface. More specifically, as shown in FIG. 1 , the holding means 3 includes a rectangular X-axis movable plate 31 mounted on the base 2 so as to be movable in the X-axis direction, a rectangular Y-axis movable plate 32 mounted on the X-axis movable plate 31 so as to be movable in the Y-axis direction, a cylindrical support 33 fixed to the upper surface of the Y-axis movable plate 32, and a rectangular cover plate 34 fixed to the upper end of the support 33. The chuck table 35 is disposed so as to extend upward through an elongated hole formed in the cover plate 34. The chuck table 35 is configured to be rotatable by a rotation drive means (not shown) housed in the support 33. A circular suction chuck 35a, made of a porous material with air permeability and having an XY plane, defined by X and Y coordinates, as a holding surface, is disposed on the upper surface of the chuck table 35. The suction chuck 35a is connected to a suction means (not shown) by a flow path passing through the support 33, and four clamps 36 are arranged at equal intervals around the suction chuck 35a to grip the frame F when holding the sapphire substrate 10 on the chuck table 35.

[0021] The X-axis feed means 4a converts the rotational motion of the motor 41 into linear motion via a ball screw 42 and transmits it to the X-axis movable plate 31, moving the X-axis movable plate 31 in the X-axis direction along a pair of guide rails 2a, 2a arranged along the X-axis direction on the base 2. The Y-axis feed means 4b converts the rotational motion of the motor 43 into linear motion via a ball screw 44 and transmits it to the Y-axis movable plate 32, moving the Y-axis movable plate 32 in the Y-axis direction along a pair of guide rails 31a, 31a arranged along the Y-axis direction on the X-axis movable plate 31.

[0022] The horizontal wall 5b of the frame 5 accommodates an optical system constituting the laser irradiation means 6 and an imaging means 7. A condenser 61, which constitutes part of the laser irradiation means 6 and irradiates a laser beam onto the sapphire substrate 10 held on the chuck table 35, is disposed on the underside of the tip of the horizontal wall 5b. The imaging means 7 is a means for capturing an image of the sapphire substrate 10 held on the chuck table 35 to detect the position and orientation of the sapphire substrate 10, the position to be irradiated with the laser beam, etc., and is disposed adjacent to the condenser 61 in the X-axis direction.

[0023] The control means 100 is configured by a computer and includes a central processing unit (CPU) that performs calculations according to a control program, a read-only memory (ROM) that stores the control program, etc., a readable and writable random access memory (RAM) that temporarily stores detected values, calculation results, etc., an input interface, and an output interface (details not shown in the drawings). The control means 100 is connected to the above-mentioned laser irradiation means 6, imaging means 7, display means 8, X-axis feed means 4a, Y-axis feed means 4b, etc., and image information captured by the imaging means 7 is stored in an appropriate memory of the control means 100 and can be displayed on the display means 8.

[0024] (holding process) Once the above-described laser processing apparatus 1 is prepared, a holding step is performed in which the sapphire substrate 10 is held on the chuck table 35 positioned at the carry-in / out position shown in Fig. 1. More specifically, the sapphire substrate 10 supported by the frame F via the above-described adhesive tape T is transported to the laser processing apparatus 1 and placed on the suction chuck 35a of the chuck table 35 positioned at the carry-in / out position. A suction means (not shown) is activated to generate a negative pressure in the suction chuck 35a for suction, and the frame F is gripped and held by the clamp 36.

[0025] (Setting process) After the holding step described above has been performed, a setting step is performed in which the sapphire substrate 10 held on the chuck table 35 is imaged by the imaging means 7, the region to be processed is set, and the coordinates are stored. More specifically, the X-axis feed means 4a is operated to move the sapphire substrate 10 directly below the imaging means 7, as shown in FIG. 4. Next, the imaging means 7 images the region of the sapphire substrate 10 where the orientation flat 10b is formed, and the image is displayed on the display means 8. At this time, the linear portion Fd of the frame F is aligned along the X-axis direction, and the center of the opening Fa of the frame F is positioned at the center of the chuck table 35. Here, if the sapphire substrate 10 is not precisely positioned in the center of the opening Fa of the frame F and the straight portion Fd of the frame F and the orientation flat 10b of the sapphire substrate 10 are not completely parallel, for example, as displayed on the display means 8 shown in Figure 4, the hairline 8a displayed along the X-axis direction in the center of the display means 8 may not completely coincide with the orientation flat 10b of the sapphire substrate 10.

[0026] Therefore, as shown in display means 8' below display means 8 in Figure 4, the above-mentioned rotation drive means that rotates chuck table 35 is operated to rotate sapphire substrate 10 in the direction indicated by arrow R1, thereby aligning orientation flat 10b and the above-mentioned hairline 8a (rotation correction), and the above-mentioned X-axis feed means 4a is operated to position orientation flat 10b in the center of the X-axis direction of display means 8 (X-coordinate correction), and at the same time, Y-axis feed means 4b is operated to position orientation flat 10b so that it coincides with hairline 8a in the Y-axis direction (Y-coordinate correction). 3, the control means 100 stores coordinate information of the division lines 14, which serve as starting points for division on the sapphire substrate 10 when dividing the sapphire substrate 10 into individual chips 12, and therefore, as shown in Fig. 5, XY coordinates (shown by dashed lines) based on the coordinate information of the division lines 14, which serve as starting points for division, are set on the sapphire substrate 10 taking into account the rotation correction, X-coordinate correction, and Y-coordinate correction described above, and stored in the control means 100. At this time, in addition to the XY coordinates of the division lines 14, the XY coordinates to be processed also store the XY coordinates of marks P1 to P16, which serve as marks when processing the division lines 14, which are formed in a mark forming step described later.

[0027] As can be seen from Figure 5, the XY coordinates of the marks P1 to P16 are set to correspond to the XY coordinates of the planned division lines 14, and are preferably set in, for example, the outer circumferential excess area where the product chips 12 are not formed. The markers that form the combinations of P1 (x1, y1) and P8 (x1, y8), P3 (x3, y3) and P6 (x3, y6), P9 (x8, y8) and P16 (x8, y1), and P11 (x10, y6) and P14 (x10, y3) shown in the figure are markers of the planned division line 14 along the Y-axis direction in the figure, and the markers that form the combinations of P2 (x2, y2) and P15 (x9, y2), P4 (x4, y4) and P13 (x11, y4), P5 (x4, y5) and P12 (x11, y5), and P7 (x2, y7) and P10 (x9, y7) are markers of the planned division line 14 along the X-axis direction in the figure. The mark does not necessarily have to be on the X coordinate or Y coordinate that coincides with the planned division line 14, but can be a coordinate that is a predetermined distance away from the X coordinate or Y coordinate of the planned division line 14.

[0028] As shown in the figure, the marks do not need to be set corresponding to all the planned division lines 14, but can be set for each of a plurality of the planned division lines 14. In the illustrated embodiment, a total of 16 marks P1 to P16 are set, but the number of marks to be set is determined appropriately depending on the size of the plate-like object, the size of the chip 12, the intervals between the planned division lines 14, etc.

[0029] (Marking process) After the above setting step has been carried out, as shown in FIG. 6(a), a mark forming step is carried out in which the X-axis feed means 4a, the Y-axis feed means 4b, and the laser irradiation means 6 are operated based on the XY coordinates of the marks P1 to P16 set in the above setting step to form the marks P1 to P16.

[0030] In this embodiment, the wavelength of the laser beam LB1 irradiated by the laser irradiation means 6 is selected to be a wavelength that is transparent to the sapphire substrate 10, and that forms a modified layer by irradiating the sapphire substrate 10 with a focal point positioned inside the sapphire substrate 10 in this mark formation step and in a processing step described later. As the laser beam LB1 that is transparent to the sapphire substrate 10, for example, a laser beam having a wavelength of 1045 nm is selected.

[0031] As shown in FIG. 6(b), the focal point of the laser beam LB1 irradiated to form the marks P1 to P16 is set at a depth of, for example, 80 μm from the surface 10a of a 150 μm-thick sapphire substrate 10. The laser beam LB1 is sequentially irradiated with the focal point positioned at the XY coordinates and depth positions of the marks P1 to P16 set in the setting process described above, forming modified layers at each mark position, and marks P1 to P16 made of the modified layers are formed. The average output of the laser beam LB1 used to form the marks P1 to P16 is, for example, 0.05 W, and the repetition frequency is 100 kHz. The mark forming process is completed through the above procedure. The output of the laser beam LB1 used to form the marks is set to be smaller than the output of the laser beam LB2 used in the processing process described below. This prevents the marks P1 to P16 from being formed of modified layers from having an effect on the processing positions on the sapphire substrate 10 due to, for example, cumulative expansion caused by the modified layers.

[0032] (Processing process) As described above, once the marks P1 to P16 have been formed, the marks P1 to P16 formed on the sapphire substrate 10 are imaged by the imaging means 7, and the X-axis feed means 4a, Y-axis feed means 4b and laser irradiation means 6 are operated to irradiate the laser beam LB2 onto the coordinate positions where the planned division lines 14, which are the areas to be processed, are set, thereby performing the processing step of processing the sapphire substrate 10 into individual chips 12.

[0033] More specifically, for example, using as a reference a line in the X-axis direction formed by a combination of the above-mentioned marks P2 and P15 among the marks P1 to P16 captured by the imaging means 7, the XY coordinates of the processing start position of the predetermined division line 14 closest to the orientation flat 10b are identified, and the processing start position is positioned directly below the condenser 61 of the laser irradiation means 6. Note that immediately after the processing step has started, in a state where laser processing of the predetermined division line 14 has not yet been performed, there is no deviation from the XY coordinates of the predetermined division line 14 set in the setting step. Therefore, the XY coordinates of the processing start position of the predetermined division line 14 closest to the orientation flat 10b, which are stored in advance in the control means 100, may be positioned directly below the condenser 61 of the laser irradiation means 6 without using as a reference the marks P2 and P15 captured by the imaging means 7.

[0034] 7(a), a laser beam LB2 is irradiated from the condenser 61 while the sapphire substrate 10 is processed and fed in the X-axis direction by the X-axis feed means 4a to form a modified layer S along the dividing line 14. The wavelength of the laser beam LB2 is selected to be a wavelength (1045 nm) that is transparent to the sapphire substrate 10, similar to the wavelength of the laser beam LB1 used to form the marks P1 to P16 described above. The position of the focal point when irradiating the laser beam LB2 is set to a position shallower than the depth at which the marks were formed, for example, a depth of 50 μm from the surface 10a of the sapphire substrate 10. The average power when irradiating the laser beam LB2 is preferably set to be greater than the average power when the marks P1 to P16 were formed in the mark forming step, for example, to be 0.5 W. Other laser processing conditions are set, for example, at a repetition frequency of 100 kHz and a processing feed rate of 800 mm / s, and laser processing is performed.

[0035] As described above, once the modified layer S has been formed along the predetermined dividing lines 14, the sapphire substrate 10 is index-fed in the Y-axis direction at the interval between adjacent dividing lines 14, so that adjacent unprocessed dividing lines 14 in the Y-axis direction are positioned directly below the condenser 61. Then, in the same manner as described above, the focal point of the laser beam LB2 is positioned inside the dividing lines 14 of the sapphire substrate 10 and irradiated, and the sapphire substrate 10 is processed and fed in the X-axis direction to form the modified layer S.

[0036] Here, as described above, when the modified layers S are formed on the multiple division lines 14 along the X-axis direction, slight bulges due to the modified layers S accumulate in the Y-axis direction, which may cause the positions of the division lines 14 to be shifted in the Y-axis direction to an unacceptable extent, resulting in the modified layers S not being formed in the appropriate positions. Therefore, before such a shift occurs, when the position for processing the next division lines 14 corresponding to the marks P4 and P13 is reached, the X-axis feed means 4a is operated to position the sapphire substrate 10 directly under the imaging means 7, and an image is taken to detect the X and Y coordinates of the marks P4 and P13. This detects the amount of deviation from the Y coordinates of the marks P4 and P13 set in the setting step and formed in the mark forming step, and the Y coordinate of the next division line 14 to be laser-processed is corrected based on the Y coordinates of the newly detected marks P4 and P13. Next, based on the corrected XY coordinates of the planned division lines 14, the processing start position of the planned division lines 14 is positioned directly below the condenser 61 of the laser irradiation means 6. Then, the focusing point position is positioned inside the planned division lines 14, and the laser beam LB2 is irradiated from the condenser 61, while the sapphire substrate 10 is processed and fed in the X-axis direction by the X-axis feed means 4a to form modified layers S. By this procedure, modified layers S are formed along a plurality of planned division lines 14 adjacent in the Y-axis direction.

[0037] As described above, laser processing is performed on multiple adjacent division lines 14 in the Y-axis direction to form modified layers S, and when the position for processing the next division lines 14 corresponding to the marks P5 and P12 is reached, the sapphire substrate 10 is positioned directly below the imaging means 6 and imaged using the same procedure as described above, and the X and Y coordinates of the marks P5 and P12 are detected. This detects the amount of deviation from the Y coordinates of the marks P5 and P12 set in the setting step and formed in the mark forming step, and the Y coordinate of the next division line 14 to be laser processed is corrected based on the newly detected Y coordinates of the marks P5 and P12. Next, based on the corrected X and Y coordinates of the division lines 14, the processing start position of the division line 14 is positioned directly below the condenser 61 of the laser irradiation means 6. Then, the focal point position is positioned inside the planned division lines 14, and in the same manner as described above, the laser beam LB2 is irradiated from the condenser 61, and the sapphire substrate 10 is processed and fed in the X-axis direction by the X-axis feed means 4a, to form a modified layer S along the planned division lines 14. Next, the sapphire substrate 10 is index-fed in the Y-axis direction at the interval between adjacent planned division lines 14, so that adjacent unprocessed planned division lines 14 in the Y-axis direction are positioned directly below the condenser 61. Then, in the same manner as described above, the focal point of the laser beam LB2 is positioned inside the planned division lines 14 of the sapphire substrate 10, and the laser beam LB2 is irradiated, and the sapphire substrate 10 is processed and fed in the X-axis direction to form a modified layer S.

[0038] As described above, the sapphire substrate 10 is imaged frequently by the imaging means 7 at intervals at which marks serving as references for the division lines 14 along the X-axis direction are formed, the positions of the marks are detected, and the position at which the laser beam LB2 is irradiated is adjusted based on the marks. This prevents slight bulges due to the modified layer S from accumulating in the Y-axis direction and causing an unacceptable deviation, which would otherwise cause the positions of the division lines 14 to deviate from the appropriate positions. This allows the laser beam LB2 to be accurately irradiated onto the areas to be processed. In this way, the sapphire substrate 10 is processed and fed in the X-axis and Y-axis directions to form modified layers S along all of the division lines 14 along the X-axis direction.

[0039] Next, the sapphire substrate 10 is rotated 90 degrees to align the unprocessed division lines 14, which are perpendicular to the division lines 14 along which the modified layers S have already been formed, in the X-axis direction. At this time, similar to the procedure described above, the sapphire substrate 10 is imaged by the imaging means 7 to capture images of the marks P3 and P6, and the amount of deviation of the marks P3 and P6 from the Y coordinates set in the setting step is detected. Then, using the Y coordinates of the new marks P3 and P6 as references, the positions of the division lines 14 corresponding to the marks P3 and P6 are set, and modified layers S are formed along the unprocessed division lines 14 in the same procedure as described above. Thereafter, similar to the procedure for forming modified layers S along the division lines 14 described above, laser processing is performed along the adjacent division lines 14, and the marks P1 and P8, P9 and P16, and P11 and P14 are imaged and detected, and the position to which the laser beam LB2 is irradiated is frequently adjusted based on the marks. This prevents slight bulges caused by the modified layers S from accumulating and causing the positions of the planned dividing lines 14 to deviate unacceptably from the proper positions. The modified layers S may be formed in a plurality of layers in the thickness direction. In this manner, as shown in FIG. 7( b), the modified layers S are formed in a lattice pattern along all of the planned dividing lines 14 set on the sapphire substrate 10, and the sapphire substrate 10 is processed into individual chips 12, completing the processing step. This completes the method for processing a plate-like object according to this embodiment. In the embodiment described with reference to FIG. 7, processing is performed based on the coordinates of the planned dividing lines 14 set in the setting step described with reference to FIG. 4. However, when the modified layers S are formed along the planned dividing lines 14, the modified layers S may be formed up to the outer peripheral edge of the sapphire substrate 10.

[0040] Once the modified layer S has been formed along the intended dividing lines 14 by the above-described processing steps, an external force can be applied to the sapphire substrate 10 to divide it into individual chips 12. The manner in which the external force is applied is not particularly limited, but for example, an elastic roller can be pressed against the sapphire substrate 10 from above and rolled to divide it into individual chips 12 along the modified layer S. Alternatively, the adhesive tape T supporting the sapphire substrate 10 may be radially expanded to apply an external force along the modified layer S to divide it into individual chips 12.

[0041] In the above embodiment, the plate-like workpiece is described as a sapphire substrate, but the present invention is not limited to this and can be applied to cases where a plate-like workpiece that does not have any planned dividing lines or devices is divided into chips, and may be applied, for example, when processing a glass plate.

[0042] Furthermore, in the above-described embodiment, the chip 12 formed from the sapphire substrate 10 has a simple rectangular shape, but the present invention is not limited to this. For example, as can be seen from another embodiment of a chip 12' shown in FIG. 8(a) and FIG. 8(b), which is an enlarged view of part A in FIG. 8(a), the chip 12' may have a pentagonal shape, with a rectangular base and one corner 12a missing while leaving a portion of each adjacent side. The illustrated chip 12' has a rectangular base with a side length of 500 μm, for example, and one corner 12a missing while leaving a portion of each adjacent side, 240 μm and 260 μm, to form a pentagon.

[0043] Furthermore, in the above-described embodiment, the markings are set in the peripheral excess area where the chips 12 are not formed. However, the present invention is not limited to this. For example, in another embodiment shown in FIG. 8, the shape of the chip 12′ is a pentagon based on a rectangle with sides of 500 μm, with one corner 12a missing and a portion of the adjacent sides (240 μm and 260 μm) remaining. As shown in FIGS. 8(a) and 8(b), the position of the markings formed in the marking formation step may be set in the area of ​​the missing corner 12a, and the marks P1′ to P12′ may be formed in that area. By doing so, for example, even if the chips 12′ are set to be formed over the entire area of ​​the sapphire substrate 10 and there is not enough excess area on the periphery, it is possible to form effective marks P1′ to P12′.

[0044] According to the above-described embodiment of the present invention, when a plate-like object having no planned dividing lines or devices is divided into chips to manufacture optical components, device covers, etc., it is possible to perform laser processing while adjusting the index feed amount using the marks formed in the mark forming process, thereby eliminating the problem of producing products with irregular chip sizes and shapes. [Explanation of symbols]

[0045] 1: Laser processing equipment 2: Base 3: Holding means 31:X-axis movable plate 32: Y-axis direction movable plate 33: Strut 34: Cover plate 35: Chuck table 35a: Suction chuck 36: Clamp 4: Processing feed means 4a: X-axis feed means 41: Motor 42: Ball screw 4b: Y-axis feed means 43: Motor 44: Ball screw 5:Frame body 6: Laser irradiation means 61: Concentrator 7: Imaging means 8:Display means 8a: Hairline 10: Sapphire substrate 10a: surface 10b: Orientation Flat 12, 12': Chip 14: Planned division line 100: Control means F: Frame Fa: Opening Fb, Fc: Notch Fd: Straight section P1~P16: Landmarks P1'~P12': Landmark LB1, LB2: Laser beam

Claims

1. A method for processing a plate-like object into a plurality of chips, comprising: a preparation step of preparing a laser processing device including a rotatable chuck table for holding a plate-like object, a laser irradiation means for irradiating a laser beam onto the plate-like object held on the chuck table to form a starting point for division, an imaging means for imaging the plate-like object held on the chuck table, an X-axis feed means for feeding the chuck table and the laser irradiation means in the X-axis direction for processing, a Y-axis feed means for feeding the chuck table and the laser irradiation means in the Y-axis direction perpendicular to the X-axis direction for processing, and a control means; a holding step of holding a plate-like object on the chuck table; a setting step of imaging the plate-like object held on the chuck table with the imaging means, setting an area to be processed, and storing coordinates; a mark forming step of operating the X-axis feed means, the Y-axis feed means, and the laser irradiation means based on the coordinates to form a mark corresponding to the area to be processed; a processing step in which the mark formed on the plate-like object is imaged by the imaging means, and the X-axis feed means, the Y-axis feed means, and the laser irradiation means are operated to irradiate a laser beam onto an area to be processed, thereby processing the plate-like object into chips; A method for processing a plate-like object comprising the steps of:

2. 2. A method for processing a plate-like object as described in claim 1, wherein the wavelength of the laser beam emitted by the laser irradiation means is transparent to the plate-like object, and in the mark formation process and the processing process, the focal point of the laser beam is positioned inside the plate-like object to form a modified layer.

3. 2. The method for processing a plate-like object according to claim 1, wherein the output of the laser beam irradiated in the mark forming step is set to be smaller than the output of the laser beam irradiated in the processing step.

4. 2. The method for processing a plate-like object according to claim 1, wherein in the mark forming step, the mark is formed in an area where no chip is to be formed.

5. 2. The method for processing a plate-like object according to claim 1, wherein after said processing step, an external force is applied to the plate-like object to divide it into individual chips.

6. The shape of the chip is a pentagon with one corner missing from a rectangle, 2. The method for processing a plate-like object according to claim 1, wherein in the mark forming step, the mark is formed in the region of the missing corner.

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