JP7584308B2 - Wafer cutting method - Google Patents

Description

The present invention relates to a method for cutting a wafer.

In a method for cutting a wafer, it is known that an operation called a kerf check is performed during cutting to check the position and quality of the cut groove. The kerf check involves imaging the cut groove to measure chipping, measuring the width of the cut groove, and hairline alignment to measure and correct the deviation (cut position deviation) between the processing position recognized by the microscope and the position where the cut groove is actually formed (see, for example, Patent Documents 1 and 2).

JP 2001-298000 A JP 2008-258496 A

When performing a kerf check, it is necessary to remove water droplets from the imaging area in order to capture an image. Air is sprayed from a nozzle installed on the underside of the imaging unit to remove the water droplets before imaging. However, there was a problem in that if the area was allowed to dry with cutting debris still attached, it would not be removed even after subsequent cleaning.

The present invention was made in consideration of these problems, and its purpose is to provide a wafer cutting method that can reduce the adhesion of cutting debris caused by drying during kerf checking.

In order to solve the above-mentioned problems and achieve the object, the present invention provides a wafer cutting method for cutting a wafer having a device region in which a plurality of devices are formed and a peripheral excess region surrounding the device region along a planned division line that divides the plurality of devices, the method comprising: a holding step of holding the wafer on a holding table; and a cutting step of cutting the wafer held on the holding table with a cutting blade along the planned division line while supplying cutting water to a processing point, thereby forming a cutting groove . The processing device is installed adjacent to the holding table. and a second holding table which is placed on the wafer and which holds a dummy wafer, the method for cutting the wafer further comprises a hairline alignment step of forming a second cutting groove in the dummy wafer with the cutting blade, measuring a deviation between a hairline of an imaging unit having a hairline which is a planned cutting line of the cutting blade and the second cutting groove, and correcting a positional relationship between the imaging unit and the cutting blade, and further comprising a cleaning step of supplying cleaning water to the wafer held on the holding table and cleaning a surface of the wafer during the hairline alignment step .

The method may further include a kerf check step in which air is sprayed onto an area including a portion of the surface of the device to remove cutting water adhering to the surface, and then an image of the area into which the air was sprayed is taken to confirm at least the position of the cutting groove, and the kerf check step may be carried out after the cleaning step.

The present invention can reduce the adhesion of cutting debris caused by drying during kerf checking.

FIG. 1 is a perspective view showing a configuration example of a processing device for carrying out a wafer cutting method according to the first embodiment. FIG. 2 is a perspective view showing a processing unit of the processing apparatus of FIG. FIG. 3 is a cross-sectional view showing an imaging unit and an air injection unit of the processing apparatus of FIG. FIG. 4 is a flowchart showing an example of a processing procedure of the wafer cutting method according to the first embodiment. FIG. 5 is a perspective view for explaining a check region in the wafer cutting method according to the first embodiment. FIG. 6 is a top view showing a main part of a processing device for carrying out a wafer cutting method according to the second embodiment. FIG. 7 is a flowchart showing an example of a processing procedure of the wafer cutting method according to the second embodiment. FIG. 8 is a diagram for explaining the hairline alignment step in FIG. FIG. 9 is a top view showing a main part of a wafer on which the wafer cutting method according to the third embodiment is performed. FIG. 10 is a flowchart showing an example of a processing procedure of the wafer cutting method according to the third embodiment.

The following describes in detail the form (embodiment) for carrying out the present invention with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. The components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Various omissions, substitutions, or modifications of the configuration can be made without departing from the spirit of the present invention.

[Embodiment 1]
A wafer cutting method according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a configuration example of a processing device 1 for carrying out the wafer cutting method according to the first embodiment. FIG. 2 is a perspective view showing a processing unit 20 of the processing device 1 of FIG. 1. FIG. 3 is a cross-sectional view showing an imaging unit 30 and an air injection unit 40 of the processing device 1 of FIG. 1. As shown in FIG. 1, the processing device 1 includes a holding table 10, a second holding table 15, a processing unit 20, an imaging unit 30, an air injection unit 40, an X-axis moving unit 51, a Y-axis moving unit 52, a Z-axis moving unit 53, a control unit 60, and a cleaning water supply unit 70.

In the wafer cutting method according to the first embodiment, the wafer 100 is a processing object, i.e., a processing object processed by the processing device 1. In the first embodiment, the wafer 100 is, for example, a disk-shaped semiconductor wafer or an optical device wafer made of silicon, sapphire, silicon carbide (SiC), gallium arsenide, glass, or the like. As shown in FIG. 1, the wafer 100 has a device region 107 and a peripheral surplus region 108 on a flat surface 101. The device region 107 is a region in which a plurality of chip-sized devices 103 are formed in a region partitioned in a lattice shape by a plurality of planned division lines 102. The peripheral surplus region 108 surrounds the device region 107 over the entire circumference thereof, and is a region in which no devices 103 are formed. In the first embodiment, the wafer 100 has an adhesive tape 105 attached to the back surface 104 behind the front surface 101, and an annular frame 106 attached to the outer edge of the adhesive tape 105, but the present invention is not limited to this.

The holding table 10 includes a disk-shaped frame body with a recess formed therein and a disk-shaped suction part fitted into the recess. The suction part of the holding table 10 is formed of a porous ceramic or the like with a large number of porous holes, and is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). The upper surface of the suction part of the holding table 10 is a holding surface 11 on which the wafer 100 is placed and which suction-holds the placed wafer 100. In the first embodiment, the holding surface 11 is a holding surface on which the wafer 100 is placed with the front surface 101 facing upward, and suction-holds the placed wafer 100 from the back surface 104 side via an adhesive tape 105. The holding surface 11 and the upper surface of the frame body of the holding table 10 are arranged on the same plane and are formed along an XY plane parallel to the horizontal plane. As shown in FIG. 1, the holding table 10 is provided so as to be freely movable along the X-axis direction parallel to the horizontal direction by an X-axis moving unit 51. The holding table 10 is rotatable around the Z axis, which is parallel to the vertical direction and perpendicular to the XY plane, by a rotary drive source (not shown).

As shown in FIG. 2, the processing unit 20 includes a cutting blade 21, a spindle 22, a spindle housing 23, a mount 24, a blade cover 25, a cutting water supply unit 26, and a cutting water supply source 27. As shown in FIG. 1, the processing unit 20 is provided so as to be freely movable along the Y-axis direction, which is parallel to the horizontal direction and perpendicular to the X-axis direction, by a Y-axis moving unit 52, and is provided so as to be freely movable along the Z-axis direction by a Z-axis moving unit 53.

The cutting blade 21 is fixed to the tip of the spindle 22 via a mount 24, and rotates around an axis parallel to the Y-axis direction as the spindle 22 rotates. The spindle 22 is housed in the spindle housing 23, and is supported by the spindle housing 23 so as to be rotatable around an axis parallel to the Y-axis direction, with the tip exposed to the outside from the spindle housing 23. The blade cover 25 is attached to the front side of the spindle housing 23, and covers at least a portion of the front side of the cutting blade 21 and the spindle 22. The blade cover 25 has multiple water channels formed inside.

The cutting water supply unit 26 is provided in communication with the lower end side of the water channel inside the blade cover 25. The cutting water supply source 27 is provided in communication with the upper end side of the water channel inside the blade cover 25. The cutting water supply unit 26 supplies cutting water 29 (see FIG. 3) supplied from the cutting water supply source 27 through the water channel inside the blade cover 25 to the processing point. Here, the processing point refers to the area of the wafer 100 that is being cut by the rotating cutting blade 21, and is the area where the rotating cutting blade 21 and the wafer 100 are in contact. In the first embodiment, the cutting water 29 is, for example, pure water.

The imaging unit 30 includes an imaging element that images the surface 201 including the planned division lines 202 of the wafer 100 before processing, and the cutting grooves 110 formed in the wafer 100 after processing. The imaging element is, for example, a CCD (Charge-Coupled Device) imaging element or a CMOS (Complementary Metal Oxide Semiconductor) imaging element. In the first embodiment, the imaging unit 30 is fixed below the spindle housing 23 so as to move integrally with the processing unit 20.

The imaging unit 30 images the unprocessed wafer 100 held on the holding table 10, obtains an image for performing alignment to align the wafer 100 with the cutting blade 21 of the processing unit 20, and outputs the obtained image to the control unit 60. The imaging unit 30 also images the wafer 100 held on the holding table 10 during or after processing, obtains an image for performing a so-called kerf check to automatically check the quality of the cut groove 110, and outputs the obtained image to the control unit 60.

As shown in FIG. 3, the imaging unit 30 includes an objective lens 31 and a shutter 32. The objective lens 31 faces the surface 101 of the wafer 100 held on the holding table 10 and collects light from the surface 101 of the wafer 100. The shutter 32 selectively opens and closes the gap between the objective lens 31 and the surface 101 of the wafer 100 held on the holding table 10. During cutting processing while supplying cutting water 29 by the processing unit 20 or during air injection by the air injection unit 40, the shutter 32 closes the gap between the objective lens 31 and the surface 101 of the wafer 100 held on the holding table 10 to prevent the cutting water 29 from scattering toward the objective lens 31, and during imaging by the imaging element, opens the gap between the objective lens 31 and the surface 101 of the wafer 100 held on the holding table 10.

As shown in FIG. 3, the air injection unit 40 includes an air injection nozzle 41, an air supply source 42, and a nozzle adjustment unit 43. The air injection unit 40 is fixed to the side of the imaging unit 30, and moves integrally with the processing unit 20 in the same manner as the imaging unit 30.

The air injection nozzle 41 is provided with a tip side facing the imaging area 120 on the surface 101 side of the wafer 100 held on the holding table 10. Here, the imaging area 120 is an area on the surface 101 side of the wafer 100 held on the holding table 10 that is imaged by the imaging element of the imaging unit 30. The air supply source 42 is provided in communication with the base end side of the air injection nozzle 41. The nozzle adjustment unit 43 is provided on the side of the air injection nozzle 41, and adjusts the injection direction of the air 49 by the air injection nozzle 41 by rotating the air injection nozzle 41 around the Z axis. The air injection unit 40 removes the cutting water 29 adhering to the imaging area 120 by injecting the air 49 supplied from the air supply source 42 by the air injection nozzle 41 toward the imaging area 120. In the first embodiment, the air 49 supplied from the air supply source 42 and injected from the air injection nozzle 41 is, for example, compressed air.

The control unit 60 controls the operation of each component of the processing device 1 to cause the processing device 1 to perform cutting processing of the wafer 100. In the first embodiment, the control unit 60 includes a computer system. The computer system included in the control unit 60 includes an arithmetic processing device having a microprocessor such as a CPU (Central Processing Unit), a storage device having a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an input/output interface device. The arithmetic processing device of the control unit 60 performs arithmetic processing according to a computer program stored in the storage device of the control unit 60, and outputs control signals for controlling the processing device 1 to each component of the processing device 1 via the input/output interface device of the control unit 60.

The control unit 60 performs a kerf check based on an image of the cutting groove 110. Specifically, the kerf check detects any of the check items such as the cut position deviation (off-center), kerf width, chipping width from the kerf center, and max chipping width from the kerf end for the cutting groove 110 based on the image of the cutting groove 110, and checks the quality of the cutting groove 110 by judging the pass/fail of the detected value. The cut position deviation (off-center) is the value of the widthwise deviation of the kerf center, which is the center line representing the center position of the cutting groove 110 in the width direction, from the center line of the division planned line 102. The kerf width is the distance (spacing) between both ends of the cutting groove 110 in the area confirmed by the kerf check. The chipping width from the kerf center is the distance between the end of the largest chipping in the width direction and the center of the cutting groove 110 in the width direction in the area confirmed by the kerf check. The maximum chipping width from the kerf end is the distance between the end of the largest chipping in the width direction within the area checked by the kerf check and the end of the cutting groove 110. The pass/fail judgment is made as follows: if the detected value is within the range of the tolerances preset for each check item, it is passed; if it is outside the range of the tolerances, it is failed (result error).

As shown in FIG. 1, the processing apparatus 1 further includes a cassette mounting table 81, a cleaning unit 82, and a transport unit 83. The cassette mounting table 81 is a mounting table for mounting a cassette 85, which is a container for storing multiple wafers 100, and raises and lowers the mounted cassette 85 in the Z-axis direction. The cleaning unit 82 cleans the wafer 100 after cutting processing and removes foreign matter such as cutting chips adhering to the wafer 100. The transport unit 83 transports the wafer 100 between the holding table 10, the cleaning unit 82, and the cassette 85.

The processing device 1 may further include a display unit (not shown). The display unit displays a screen for setting the conditions for the cutting processing of the processing device 1, an image for performing alignment, an image for performing a kerf check, the inspection results of the cut groove 110 by the kerf check, etc. The display unit is configured with a liquid crystal display device or the like. The display unit is provided with an input unit that is used when the operator inputs information related to the cutting conditions of the processing device 1, etc. The input unit provided on the display unit is configured with at least one of a touch panel provided on the display unit, a keyboard, etc.

Although the second holding table 15 and the cleaning water supply unit 70 are shown in FIG. 1, they are not involved in the processing of the wafer cutting method according to the first embodiment described below, and therefore their functions and operations will be described in the second embodiment described below.

Next, this specification describes the processing of the wafer cutting method according to embodiment 1 with reference to the drawings. FIG. 4 is a flowchart showing an example of the processing procedure of the wafer cutting method according to embodiment 1. FIG. 5 is a perspective view explaining the check area 109 of the wafer cutting method according to embodiment 1. As shown in FIG. 4, the wafer cutting method according to embodiment 1 includes a holding step 1001, a cutting step 1002, and a kerf check step 1003.

The holding step 1001 is a step in which the wafer 100 is held on the holding table 10. In the holding step 1001, the control unit 60 causes the holding table 10 to suction hold the wafer 100, which is placed on the holding surface 11 with the front surface 101 facing upward, on the holding surface 11 from the back surface 104 side via the adhesive tape 105. After carrying out the holding step 1001, the control unit 60 performs alignment using an image captured by the imaging unit 30, and aligns the wafer 100 on the holding surface 11 of the holding table 10 with the cutting blade 21 of the processing unit 20.

In the cutting step 1002, the wafer 100 held on the holding table 10 is cut by the cutting blade 21 along the planned dividing line 102 while supplying cutting water 29 to the processing point, and a cutting groove 110 is formed. In the cutting step 1002, the control unit 60 controls the processing unit 20 to supply cutting water 29 to the processing point by the cutting water supply unit 26, and while rotating the cutting blade 21 by the spindle 22, the X-axis moving unit 51, the Y-axis moving unit 52, and the Z-axis moving unit 53 cause the rotating cutting blade 21 to cut into the wafer 100 on the holding table 10 and move along the planned dividing line 102 relative to the wafer 100, so that the rotating cutting blade 21 cuts the wafer 100 along the planned dividing line 102, and a cutting groove 110 is formed along the planned dividing line 102.

In the kerf check step 1003, air 49 is sprayed onto the device region 107 near the peripheral excess region 108 to remove the cutting water 29 adhering to the surface 101, and then the device region 107 onto which the air 49 has been sprayed is imaged to confirm the position of at least the cutting groove 110. The kerf check step 1003 is performed after at least one cutting groove 110 has been formed by the cutting step 1002. In the first embodiment, the kerf check step 1003 may be performed after the cutting groove 110 has been formed along some of the planned division lines 102 by the cutting step 1002, or may be performed after the cutting groove 110 has been formed along all of the planned division lines 102 by the cutting step 1002.

The area in the device area 107 near the outer circumferential excess area 108 from which the cutting water 29 is removed and imaged in the kerf check step 1003 includes a part of the surface 101 of the device 103 adjacent to the outer circumferential excess area 108, and is an area of the same area as the imaging area 120. In the first embodiment, for example, as shown in FIG. 5, this is the check area 109 set across the cutting groove 110. Therefore, in the kerf check step 1003, the control unit 60 first moves the imaging unit 30 and the air injection unit 40 using the Y-axis movement unit 52 and the Z-axis movement unit 53, thereby moving the imaging area 120 of the imaging unit 30 to the check area 109.

In the kerf check step 1003, the imaging area 120 of the imaging unit 30 is moved to the check area 109, and then, as shown in FIG. 4, a drying step 1011, an imaging step 1012, and an inspection step 1013 are sequentially performed. In the drying step 1011, the control unit 60 controls the air injection unit 40 to inject air 49 supplied from the air supply source 42 toward the check area 109 by the air injection nozzle 41, thereby removing the cutting water 29 adhering to the check area 109. In the imaging step 1012, the control unit 60 causes the imaging unit 30 to image the check area 109 from which the cutting water 29 has been removed by injecting the air 49 in the drying step 1011. In inspection step 1013, the control unit 60 performs a kerf check on the cutting groove 110 formed along the planned division line 102 in the check area 109 based on the image of the check area 109 captured in imaging step 1012, to confirm the position of the cutting groove 110 and the quality of the cutting groove 110.

In the wafer cutting method according to the first embodiment, the control unit 60 judges whether or not the cutting process by the processing device 1 can be continued based on the inspection results of the inspection step 1013 (step 1004 in FIG. 4). In step 1004, if all the inspection results of the inspection step 1013 are pass, the control unit 60 judges that the cutting process by the processing device 1 can be continued (Yes in step 1004) and proceeds to step 1005 in FIG. 4. In step 1004, if any of the inspection results of the inspection step 1013 are fail, the control unit 60 judges that the cutting process by the processing device 1 can be continued (No in step 1004) and stops the cutting process by the processing device 1.

In the wafer cutting method according to the first embodiment, if the answer is Yes in step 1004, the control unit 60 determines whether cutting has been completed along all of the planned dividing lines 102 along which cutting is to be performed (step 1005 in FIG. 4). In step 1005, if all of the planned cutting has not been completed (No in step 1005 in FIG. 4), the control unit 60 resumes cutting of the wafer 100 by the processing device 1 from where it left off, and again performs the processes of cutting step 1002 and kerf check step 1003. In step 1005, if all of the planned cutting has been completed (Yes in step 1005 in FIG. 4), the control unit 60 ends the process.

In the wafer cutting method according to the first embodiment having the above-mentioned configuration, in the kerf check step 1003, the removal of the cutting water 29 by spraying air 49 and the imaging are performed in an area in the device area 107 near the peripheral excess area 108, so that the area of the device area 107 that is dried when the area is dried by spraying air 49 can be kept smaller than if the area were dried in the center of the wafer 100. As a result, the wafer cutting method according to the first embodiment has the effect of reducing the adhesion of cutting debris due to drying during the kerf check.

[Embodiment 2]
A wafer cutting method according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 6 is a top view showing a main part of a processing device 1 for carrying out the wafer cutting method according to the second embodiment. Fig. 7 is a flow chart showing an example of a processing procedure of the wafer cutting method according to the second embodiment. Fig. 8 is a diagram for explaining a hairline alignment step 1021 in Fig. 7. In Figs. 6, 7 and 8, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 6, the second holding table 15 is located off the movement path of the holding table 10 along the X-axis direction and directly below the movement path of the spindle 22 of the processing unit 20 along the Y-axis direction. The second holding table 15 has a configuration similar to that of the holding table 10, and the area of the holding surface 16 is smaller than the holding surface 11 of the holding table 10. As shown in FIG. 6, the holding surface 16 of the second holding table 15 holds the dummy wafer 150 by suction.

The dummy wafer 150 is made of the same material as the wafer 100, and is formed into a plate shape with an area perpendicular to the thickness direction smaller than that of the wafer 100, and does not have the planned division lines 102 or devices 103 formed therein. The dummy wafer 150 is, for example, a small piece of silicon. The dummy wafer 150 is cut by the cutting blade 21 to form a second cutting groove 160 (see FIG. 8).

The processing device 1 can move the cutting blade 21 directly above the dummy wafer 150 on the holding surface 16 of the second holding table 15 by moving the processing unit 20 along the Y-axis direction using the Y-axis moving unit 52, and can further move the processing unit 20 downward along the Z-axis direction using the Z-axis moving unit 53 while rotating the cutting blade 21, thereby cutting the dummy wafer 150 on the second holding table 15 with the cutting blade 21 to form a second cutting groove 160.

In the processing device 1, the imaging unit 30 and the air injection unit 40 are fixed below the spindle housing 23 so as to move integrally with the processing unit 20. Therefore, the processing device 1 can use the Y-axis moving unit 52 and the Z-axis moving unit 53 to move the imaging area 120 where the imaging unit 30 takes an image and the air injection unit 40 injects air 49 to an area including the second cutting groove 160 formed in the dummy wafer 150.

Alternatively, the second holding table 15 may have a drive mechanism for moving in the X-axis direction, and the imaging unit 30 and the air injection unit 40 may be installed adjacent to the processing unit 20 in the X-axis direction. Alternatively, the second holding table 15 may be fixed to the holding table 10, and the second cutting groove 160 may be formed in the dummy wafer 150 by driving the holding table 10 in the X-axis direction, and the imaging unit 30 and the air injection unit 40 may be installed adjacent to the processing unit 20 in the X-axis direction.

As shown in FIG. 6, the cleaning water supply unit 70 is provided along the Y-axis direction so as to straddle the upper part of the moving path of the holding table 10 along the X-axis direction. The cleaning water supply unit 70 includes a cleaning water supply section 71 and a cleaning water supply source 72. The cleaning water supply source 72 is provided in communication with the cleaning water supply section 71. The cleaning water supply unit 70 supplies cleaning water supplied from the cleaning water supply source 72 to the wafer 100 held on the holding table 10 moving below the cleaning water supply section 71 extending in the Y-axis direction, by the cleaning water supply section 71, thereby cleaning the front surface 101 of the wafer 100. In the first embodiment, the cleaning water supplied from the cleaning water supply source 72 and supplied by the cleaning water supply section 71 is, for example, pure water.

Next, this specification will explain the process of the wafer cutting method according to embodiment 2 with reference to the drawings. As shown in FIG. 7, the wafer cutting method according to embodiment 2 is a modification of embodiment 1, which further includes a hairline alignment step 1021, further includes a cleaning step 1022 during the execution of the hairline alignment step 1021, and further includes a kerf check step 1003 after the execution of the cleaning step 1022.

The hairline alignment step 1021 is a step in which a second cutting groove 160 is formed in a dummy wafer 150 with a cutting blade 21, the misalignment between the hairline 210 (see FIG. 8) of the imaging unit 30, which has a hairline 210 (see FIG. 8) that is the intended cutting line of the cutting blade 21 within the imaging screen 200 (see FIG. 8), and the second cutting groove 160 is measured, and the positional relationship between the imaging unit 30 and the cutting blade 21 is corrected.

In the hairline alignment step 1021, the control unit 60 first rotates the cutting blade 21 aligned to a predetermined position (e.g., the center of the dummy wafer 150) relative to the dummy wafer 150 on the second holding table 15, moves the cutting blade 21 along the cutting feed direction relative to the dummy wafer 150, cuts the dummy wafer 150 by a predetermined amount with the cutting blade 21 to cut the dummy wafer 150 to form the second cutting groove 160, and then raises the cutting blade 21 to move it away from the dummy wafer 150, thus performing a so-called chopper cut. In the hairline alignment step 1021, the control unit 60 then moves the imaging unit 30 to a position corresponding to the position where the cutting blade 21 formed the second cutting groove 160 based on the preset positional relationship between the imaging unit 30 and the cutting blade 21, and captures the dummy wafer 150 with the moved imaging unit 30 to obtain an image screen 200.

In the hairline alignment step 1021, as shown in FIG. 8, the hairline deviation 170 is measured, which is the deviation between the hairline 210, which is the planned cutting line of the cutting blade 21 set in advance in the imaging screen 200, and the kerf center of the second cutting groove 160 imaged in the imaging screen 200. In the hairline alignment step 1021, the positional relationship between the imaging unit 30 and the cutting blade 21 is corrected in a direction that eliminates the hairline deviation 170 based on the measured hairline deviation 170. When the second holding table 15 moves in the X-axis direction, the hairline alignment step 1021 may move the second holding table 15 in the X-axis direction with the cutting blade 21 lowered to a depth that does not completely cut the dummy wafer 150, to form the second cutting groove 160 from one end of the dummy wafer 150 to the other end.

Cleaning step 1022 is a step in which cleaning water is supplied to the wafer 100 held on the holding table 10 to clean the surface 101 of the wafer 100. In cleaning step 1022, the control unit 60 moves the holding table 10 by the X-axis movement unit 51 to pass under the cleaning water supply unit 71 extending in the Y-axis direction, thereby supplying cleaning water to the wafer 100 held on the holding table 10 to clean the surface 101 of the wafer 100. Alternatively, the cleaning water supply unit 71 may move in the X-axis direction to clean the surface 101 of the wafer 100.

When the spindle 22 to which the cutting blade 21 is attached expands due to heat generated during cutting processing, or when the cutting blade 21 falls due to cutting load, a deviation (hairline deviation 170) occurs between the hairline 210, which is the planned cutting line recognized by the imaging unit 30, and the position where the cutting blade 21 actually cuts based on the planned cutting line. Therefore, in addition to the functions of the first embodiment, the wafer cutting method according to the second embodiment further performs hairline alignment to correct this hairline deviation 170. The wafer cutting method according to the second embodiment performs hairline alignment by forming a second cutting groove 160 on the dummy wafer 150 held on the second holding table 15, and while performing hairline alignment, the cleaning water supply unit 70 supplies cleaning water to the wafer 100 held on the holding table 10 to clean it. Therefore, in addition to the functions and effects of the first embodiment, the wafer cutting method according to the second embodiment has the function and effect of reducing the adhesion of cutting debris caused by the wafer 100 drying out during hairline alignment. In addition, the wafer cutting method according to the second embodiment can remove cutting debris by cleaning the wafer 100 while performing hairline alignment, which further prevents adhesion of cutting debris to the wafer 100. Furthermore, in the wafer cutting method according to the second embodiment, even if the kerf check step 1003 is performed after the cleaning step 1022, foreign matter is less likely to adhere to the wafer 100 even if the surface 101 of the wafer 100 is dried when the cutting groove 110 or the target 180 (see FIG. 9 of the third embodiment) is imaged, because the cutting debris has been removed by the cleaning step 1022.

[Embodiment 3]
A wafer cutting method according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 9 is a top view showing a main part of a wafer 100 on which the wafer cutting method according to the third embodiment is performed. Fig. 10 is a flow chart showing an example of a processing procedure of the wafer cutting method according to the third embodiment. In Figs. 9 and 10, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

In the third embodiment, as shown in FIG. 9, a target 180 is formed on each device 103 of the wafer 100. The target 180 has a characteristic shape and is a key pattern of a planar shape and color that can be detected in an image captured by the imaging unit 30. The target 180 is formed at a position a predetermined distance away from each of the division lines 102 surrounding the device 103 on which the target 180 is formed, and serves as a mark for detecting the division lines 102. In the example shown in FIG. 9, the target 180 is formed at a position a distance 181 away from the division line 102 along the X-axis direction in the +Y direction, and at a distance 182 away from the division line 102 along the Y-axis direction in the +X direction. In the third embodiment, the device 103 formed on the wafer 100 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), a CCD, or an image sensor such as a CMOS.

Next, this specification describes the process of the wafer cutting method according to embodiment 3 with reference to the drawings. As shown in FIG. 10, the wafer cutting method according to embodiment 3 further includes a target registration step 1031 and a distance registration step 1032 in embodiment 1, and changes the kerf check step 1003 to a target check step 1033.

The target registration step 1031 is a step for registering an arbitrary pattern of the device 103 as a target 180 for detecting the planned division line 102. In the target registration step 1031, the control unit 60 captures an image including the target 180 by aligning the imaging area 120 of the imaging unit 30 with the area including the target 180, and registers the planar shape and color of the target 180 in this image in the storage device of the control unit 60.

The distance registration step 1032 is a step for measuring and registering the distances 181, 182 from the target 180 registered in the target registration step 1031 to the planned division line 102 surrounding the device 103 on which the target 180 is formed. In the distance registration step 1032, the control unit 60 first uses the imaging unit 30 to image the planned division line 102 surrounding the device 103 on which the target 180 registered in the target registration step 1031 is formed, and obtains an image including the planned division line 102. In the distance registration step 1032, the control unit 60 then measures distances 181, 182 from the target 180 registered in the target registration step 1031 to the planned division line 102 surrounding the device 103 on which the target 180 is formed, based on the position of the target 180 in the image including the target 180 captured in the target registration step 1031, the position of the center line of the planned division line 102 in the image including the planned division line 102, and the difference in the position of the imaging unit 30 between when the image including the target 180 was captured and when the image including the planned division line 102 was captured. In the distance registration step 1032, the control unit 60 registers the measured distances 181, 182 in the storage device of the control unit 60.

When the same type of wafers 100 are processed continuously, the target registration step 1031 and the distance registration step 1032 are performed after the holding step 1001 of the first wafer 100. Therefore, the cutting process of the second and subsequent wafers 100 is performed before the holding step 1001, as shown in FIG. 10.

In the target check step 1033, air 49 is sprayed at a position 181 away from the cutting groove 110 to remove the cutting water 29 adhering to the surface 101, and then the position where the air 49 was sprayed is imaged. If the target 180 does not exist in the image, it is detected that the cutting position is misaligned. As with the kerf check step 1003, the target check step 1033 is performed after at least one cutting groove 110 has been formed by the cutting step 1002.

Specifically, the target check area from which the cutting water 29 is removed and imaged in the target check step 1033 is an area including a position that is a distance 181 away from the cutting groove 110 formed along the X-axis direction in the +Y direction and a position that is a distance 182 away from the planned division line 102 along the Y-axis direction after the cutting groove 110 is formed along the planned division line 102 parallel to the X-axis direction, and a position that is a distance 182 away from the planned division line 102 along the Y-axis direction in the +X direction after the cutting groove 110 is formed along both the planned division lines 102 parallel to the X-axis direction and the Y-axis direction. The target check area is an area including a position that is a distance 181 away from the cutting groove 110 formed along the X-axis direction in the +Y direction and a position that is a distance 182 away from the cutting groove 110 formed along the Y-axis direction in the +X direction after the cutting groove 110 is formed along both the planned division lines 102 parallel to the X-axis direction and the Y-axis direction. In the third embodiment, the distances 181 and 182 are sufficiently longer than the sides of the imaging area 120 of the imaging unit 30, so the target check area does not straddle the planned division line 102 or the cutting groove 110. Therefore, in the target check step 1033, the control unit 60 first refers to the distances 181 and 182 registered in the distance registration step 1032, and moves the imaging unit 30 and the air injection unit 40 using the Y-axis movement unit 52 and the Z-axis movement unit 53, thereby moving the imaging area 120 of the imaging unit 30 to the target check area.

In the target check step 1033, the imaging area 120 of the imaging unit 30 is moved to the target check area, and then, as shown in FIG. 4, a drying step 1041, an imaging step 1042, and an inspection step 1043 are sequentially performed. In the drying step 1041 and the imaging step 1042, the area where the air injection unit 40 sprays the air 49 to remove the cutting water 29 and the area imaged by the imaging unit 30 in the drying step 1011 and the imaging step 1012 of the first embodiment are changed to the target check area. In the inspection step 1043, the control unit 60 determines whether the target 180 is present in the image of the target check area imaged in the imaging step 1042, and if it is determined that the target 180 is present, it determines that the cutting position is not shifted, and if it is determined that the target 180 is not present, it determines that the cutting position is shifted, thereby confirming the position of the cutting groove 110. In inspection step 1043, the control unit 60 determines whether or not a target 180 is present in the image of the target check area by pattern matching the image of the target check area with the planar shape and color of the target 180 registered in target registration step 1031.

In step 1004 of the third embodiment, the control unit 60 determines whether or not the cutting process by the processing device 1 can be continued based on the determination result of the target check step 1033. In step 1004, if the control unit 60 determines that the cutting position is not shifted in the target check step 1033, it determines that the cutting process by the processing device 1 can be continued (Yes in step 1004) and proceeds to step 1005 in FIG. 4. In step 1004, if the control unit 60 determines that the cutting position is shifted in the target check step 1033, it determines that the cutting process by the processing device 1 can be continued (No in step 1004) and stops the cutting process by the processing device 1.

The wafer cutting method according to the third embodiment having the above-mentioned configuration is a modification of the first embodiment, in which the target 180 formed on each device 103 and the distances 181, 182 from the target 180 to the planned division line 102 are registered, and instead of the kerf check, the presence or absence of the target 180 is confirmed at a position distant from the cutting groove 110 by the distance 181. Therefore, the wafer cutting method according to the third embodiment performs the removal of the cutting water 29 by spraying the air 49 and the imaging in the target check area including the target 180, so there is no need to remove the cutting water 29 and image the cutting groove 110, and the time required to confirm the presence or absence of the target 180 is shorter than the time required for the kerf check, which has the effect of further reducing the adhesion of cutting debris due to drying.

In addition, the wafer cutting method according to the third embodiment has the effect of detecting problems that cannot be detected by a kerf check, such as when the warp of a warped wafer 100 is released, causing the chip-sized device 103 to move, or when the center of the planned dividing line 102 on the actual wafer 100 cannot be processed even though the planned processing line has been cut due to an error in setting the planned processing position, or when the processing position is significantly shifted and cuts into the device region 107.

The wafer cutting method according to embodiment 3 is particularly effective in reducing the time required for kerf checking when the device 103 formed on the wafer 100 is an image sensor that has little chipping and does not require chipping inspection.

The wafer cutting method according to the third embodiment may further include hairline alignment to correct this hairline misalignment 170, as in the second embodiment, and in this case, the same effect as in the second embodiment is further achieved.

The present invention is not limited to the above embodiment. In other words, the present invention can be implemented in various modifications without departing from the gist of the invention.

REFERENCE SIGNS LIST 1 Processing device 10 Holding table 15 Second holding table 20 Processing unit 21 Cutting blade 29 Cutting water 30 Imaging unit 49 Air 100 Wafer 101 Surface 102 Planned division line 107 Device area 108 Surplus outer periphery area 110 Cutting groove 180 Target 181, 182 Distance 210 Hairline

Claims (2)

A wafer cutting method for cutting a wafer having a device region in which a plurality of devices are formed and a peripheral excess region surrounding the device region along a planned division line that divides the plurality of devices, the method comprising the steps of:
a holding step of holding the wafer on a holding table;
a cutting step of cutting the wafer held on the holding table along the intended dividing lines with a cutting blade while supplying cutting water to a processing point, thereby forming cutting grooves ;
Equipped with
the processing apparatus has a second holding table that is installed adjacent to the holding table and that holds a dummy wafer;
The method for cutting the wafer comprises the steps of:
a hairline alignment step of forming a second cut groove in the dummy wafer with the cutting blade, measuring a deviation between the hairline of an imaging unit having a hairline which is a planned cutting line of the cutting blade and the second cut groove, and correcting a positional relationship between the imaging unit and the cutting blade;
The wafer cutting method further comprises, during the hairline alignment step, carrying out a cleaning step of supplying cleaning water to the wafer held on the holding table and cleaning the surface of the wafer. a kerf check step of spraying air onto an area including a part of the surface of the device to remove cutting water adhering to the surface, and then imaging the area onto which the air has been sprayed to confirm at least the position of the cutting groove;
2. The method for cutting a wafer according to claim 1, wherein the kerf check step is carried out after the cleaning step.

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