KR20230109551A - Grinding apparatus - Google Patents

Abstract

An object of the present invention is to suction-hold a workpiece by a chuck table even when the bending force of the workpiece is large.
The grinding apparatus according to the present invention forms a groove in the wafer 100 before the holding surface 22 of the chuck table 20 holds the wafer 100, thereby weakening the bending force of the wafer 100 and there is. Therefore, even when the bending force of the wafer 100 is great, the holding surface 22 of the chuck table 20 can easily suction and hold the wafer 100 . In addition, since the time required to hold the wafer 100 by the holding surface 22 can be shortened, the overall processing time of the wafer 100 by the grinding device 1 can be shortened.

Description

Grinding device {GRINDING APPARATUS}

The present invention relates to a grinding device.

When a plate-shaped workpiece, which has a bending force, is suction-held by the holding surface and ground with a grinding wheel, the outer peripheral portion of the workpiece floats off the holding surface, and the grinding wheel removes the workpiece from the holding surface. There are times when it comes off. Therefore, in the technique of Patent Literature 1, the bending force is weakened by forming cutting grooves with a cutting blade on the upper surface serving as the grinding surface of the workpiece held by the holding surface.

Patent Document 1: Japanese Unexamined Patent Publication No. 2015-223667

When forming the above-described cutting groove, cutting debris generated along with cutting is discharged using cutting water. For this reason, the formation of the cutting groove is performed in a state where the workpiece is held by the chuck table in the machining chamber. Therefore, when the bending of the workpiece is large and it is difficult to suction and hold the workpiece by the chuck table, it becomes difficult to form cutting grooves and grind the workpiece.

Accordingly, an object of the present invention is to reduce the bending force and suck and hold the workpiece by a chuck table when grinding a workpiece having a bending force at the outer circumferential portion.

A grinding device (this grinding device) of the present invention includes a chuck table for sucking and holding the lower surface of a workpiece having a bending force on its outer circumferential portion by a holding surface, and grinding the upper surface of the workpiece held by the holding surface with a grindstone. A grinding device having a grinding mechanism for grinding by a groove forming unit for forming a groove with a depth equal to or less than the depth that the grinding stone grinds on the upper surface of the workpiece before holding the workpiece by the holding surface. The groove forming unit includes a support unit for supporting a workpiece, and a laser processing unit for irradiating a laser beam having an absorption wavelength to the workpiece on an upper surface of the workpiece supported by the support unit, , The laser processing unit positions the convergence point of the laser beam according to the height of the upper surface of the workpiece supported by the support unit, forms the groove on the upper surface of the workpiece by the laser beam, and bends the workpiece upward. weaken the power

In this grinding apparatus, the groove forming unit comprises a height measuring device for measuring the height of the curved outer edge of the workpiece supported by the support unit and the height of the central upper surface of the workpiece supported by the support unit; It may have a warp amount calculation unit that calculates a difference between the height of the outer circumferential edge and the height of the central upper surface measured by the measuring device, and based on the difference calculated by the warp amount calculation unit, at least the number of grooves may be determined. A home condition determining unit may be provided.

In this grinding apparatus, before the holding surface of the chuck table holds the workpiece, a groove is formed in the workpiece by a groove forming unit to weaken the bending force of the workpiece. For this reason, even when the bending force of the workpiece is large, the workpiece can be easily sucked and held by the holding surface of the chuck table.

In addition, since the time required to hold the workpiece by the holding surface can be shortened, it is possible to shorten the overall machining time of the workpiece by the present grinding device.

1 is a perspective view showing the configuration of a grinding device according to an embodiment.
2 is a perspective view showing the configuration of a processing unit.
3 is an explanatory view showing the configuration of a Y-axis direction movement mechanism in the processing unit.
4 is an explanatory diagram showing a configuration example of a laser processing unit.
5 is an explanatory diagram showing a configuration example of a processing head in a laser processing unit.
6 is an explanatory view showing an example of a groove formed on the back surface of a wafer.
7 is an explanatory diagram showing another configuration example of a laser processing unit.

As shown in FIG. 1 , the grinding device 1 according to the present embodiment is a device for grinding a wafer 100 as a workpiece. The wafer 100 is, for example, a circular plate-like work, and has a front surface 101 and a rear surface 102 . A device (not shown) is formed on the surface 101 of the wafer 100, and a protective tape 103 is attached. The back surface 102 of the wafer 100 serves as a processing surface on which grinding processing is performed. In addition, the wafer 100 has a force that causes the outer circumferential portion to bend upward. That is, as shown in FIG. 4 , the outer peripheral portion (outer peripheral edge) of the wafer 100 curves upward toward the rear surface 102 serving as the upper surface of the wafer 100 .

The grinding machine 1 has a first machine base 10 and a second machine base 11 disposed behind the first machine base 10 (+Y direction side).

On the front side (-Y direction side) of the first device base 10, a first cassette stage 160 and a second cassette stage 162 are provided. On the first cassette stage 160, a first cassette 161 in which the wafer 100 before processing is accommodated is disposed. On the second cassette stage 162, a second cassette 163 in which the processed wafers 100 are accommodated is disposed.

The first cassette 161 and the second cassette 163 have a plurality of shelves inside, and wafers 100 are accommodated one by one on each shelf. That is, the first cassette 161 and the second cassette 163 accommodate a plurality of wafers 100 in a shelf-like manner.

The openings (not shown) of the first cassette 161 and the second cassette 163 face the +Y direction side. A robot 155 is disposed on the +Y direction side of these openings. The robot 155 includes a holding member 150 holding the wafer 100 . The robot 155 carries in (stores) the processed wafers 100 into the second cassette 163 . Further, the robot 155 takes out the unprocessed wafer 100 from the first cassette 161 and places it on the temporary placement table 154 of the temporary placement mechanism 152 .

The temporary placement mechanism 152 is used to temporarily place the wafer 100 taken out from the first cassette 161 and is provided at a position adjacent to the robot 155 . The temporary placement mechanism 152 includes a temporary placement table 154 for supporting the wafer 100, an alignment member 153 for positioning the wafer, and a rotation mechanism for rotating the temporary placement table 154 ( 151) have.

The positioning member 153 includes a plurality of positioning pins disposed outside so as to surround the temporary positioning table 154 and a slider that moves the positioning pins in the radial direction of the temporary positioning table 154 . In the alignment member 153, the alignment pins are moved toward the center in the radial direction of the provisional positioning table 154, so that the circles connecting the plurality of alignment pins are reduced in diameter. As a result, the wafer 100 supported on the temporary placement table 154 is aligned (centered) to a predetermined position. This temporary placement mechanism 152 (temporary placement table 154) functions as a support unit that supports the wafer 100.

A processing unit 110 is provided on the +Y direction side of the temporary placement mechanism 152 . This processing unit 110 and the provisional placement mechanism 152 as the support unit described above are included in the groove forming unit in this embodiment. In addition, the processing unit 110 will be described later.

Further, a carrying mechanism 170 is provided at a position adjacent to the provisional placement mechanism 152 . The carrying mechanism 170 includes a suction pad 171 that suctions and holds the wafer 100 . The carrying mechanism 170 suctions and holds the wafer 100 taken out by the robot 155 and temporarily placed on the temporary placement table 154 by the suction pad 171 to hold the chuck table 20 Place on face 22. In this way, the carrying mechanism 170 transfers the wafer 100 held by the robot 155 to the chuck table 20 .

An opening 13 is provided on the upper surface side of the second device base 11 . In the opening 13 , a chuck table 20 having a holding surface 22 holding the wafer 100 is disposed.

The chuck table 20 includes a porous member 21 and a frame body 23 accommodating the porous member 21 so that the upper surface of the porous member 21 is exposed. The upper surface of the porous member 21 is a holding surface 22 that holds the wafer 100 by suction. The holding surface 22 suction-holds the surface 101 side of the wafer 100 by communicating with a suction source (not shown). That is, the chuck table 20 suction-holds the surface 101 , which is the lower surface of the wafer 100 , by the holding surface 22 . In addition, the frame body surface 24, which is the upper surface of the frame body 23, surrounds the holding surface 22 and is formed so as to be flush with the holding surface 22 (coplanar).

The chuck table 20 is centered around a rotation axis passing through the center of the holding surface 22 in a state where the wafer 100 is held by the holding surface 22 by a table rotation mechanism (not shown) provided below the chuck table 20 . It is possible to rotate by

In addition, the chuck table 20 can be moved in the Y-axis direction by a table moving mechanism (not shown) provided in the second device base 11 .

In this embodiment, the chuck table 20 includes a work arrangement position in the -Y direction for holding the wafer 100 on the holding surface 22 and the wafer 100 held on the holding surface 22. It moves along the Y-axis direction between grinding positions on the +Y direction side to be ground.

Around the chuck table 20, a cover plate 39 that moves along the Y-axis direction together with the chuck table 20 is provided. Further, a bellows cover 12 that expands and contracts in the Y-axis direction is connected to the cover plate 39 .

Further, on the +Y direction side of the second device base 11, a column 15 is erected and installed. A grinding mechanism 70 for grinding the wafer 100 and a grinding transfer mechanism 60 are provided on the front surface of the column 15 .

The grinding transfer mechanism 60 relatively moves the chuck table 20 and the grinding stone 77 of the grinding mechanism 70 in the Z-axis direction perpendicular to the holding surface 22 (grinding transfer direction). In this embodiment, the grinding transfer mechanism 60 is configured to move the grinding stone 77 in the Z-axis direction with respect to the chuck table 20 .

The grinding transfer mechanism 60 includes a pair of Z-axis guide rails 61 parallel to the Z-axis direction, a Z-axis moving table 63 that slides on the Z-axis guide rails 61, and a Z-axis guide rail ( 61) parallel to the Z-axis ball screw 62, the Z-axis motor 64, the Z-axis encoder 65 for detecting the rotational angle of the Z-axis ball screw 62, and the Z-axis movement table 63 It has an attached holder 66. The holder 66 supports the grinding mechanism 70 .

The Z-axis moving table 63 is slidably installed on the Z-axis guide rail 61 . A nut part (not shown) is fixed to the Z-axis movement table 63 . A Z-axis ball screw 62 is screwed to this nut portion. The Z-axis motor 64 is connected to one end of the Z-axis ball screw 62 .

In the grinding feed mechanism 60, the Z-axis motor 64 rotates the Z-axis ball screw 62, so that the Z-axis movement table 63 moves along the Z-axis guide rail 61 in the Z-axis direction. . As a result, the holder 66 attached to the Z-axis movement table 63 and the grinding mechanism 70 supported by the holder 66 also move in the Z-axis direction together with the Z-axis movement table 63 .

The Z-axis encoder 65 is rotated by the Z-axis motor 64 rotating the Z-axis ball screw 62, and can recognize the rotation angle of the Z-axis ball screw 62. Then, the Z-axis encoder 65 can detect the height position of the grinding stone 77 of the grinding mechanism 70 moved in the Z-axis direction based on the recognition result.

The grinding mechanism 70 grinds the back surface 102 , which is the upper surface of the wafer 100 held by the chuck table 20 , using a grinding stone 77 . The grinding mechanism 70 includes a spindle housing 71 fixed to the holder 66, a spindle 72 rotatably held in the spindle housing 71, a spindle motor 73 for rotationally driving the spindle 72, It has a wheel mount 74 attached to the lower end of the spindle 72, and a grinding wheel 75 supported on the wheel mount 74.

The spindle housing 71 is held by the holder 66 so as to extend in the Z-axis direction. The spindle 72 extends in the Z-axis direction so as to be orthogonal to the holding surface 22 of the chuck table 20, and is rotatably supported by the spindle housing 71.

The spindle motor 73 is connected to the upper end side of the spindle 72 . By means of this spindle motor 73, the spindle 72 rotates around a rotation shaft extending in the Z-axis direction.

The wheel mount 74 is formed in a disk shape and is fixed to the lower end (top end) of the spindle 72 . The wheel mount 74 supports the grinding wheel 75 .

The grinding wheel 75 is formed so that its outer diameter may have substantially the same diameter as the outer diameter of the wheel mount 74 . The grinding wheel 75 includes an annular wheel base 76 formed of a metal material. On the lower surface of the wheel base 76, a plurality of grinding stones 77 arranged in an annular shape are fixed over the entire circumference. The grinding stone 77 is rotated by the spindle motor 73 together with the spindle 72 around its center to grind the back surface 102 of the wafer 100 held on the chuck table 20 .

Further, as shown in FIG. 1 , a thickness gauge 80 is arranged on the side of the opening 13 in the second device base 11 .

The thickness measuring instrument 80 has a holding surface height gauge 81 and an upper surface height gauge 82 . The holding surface height gauge 81 measures the height of the holding surface 22 by contacting the frame surface 24 of the frame body 23 which is flush with the holding surface 22 of the chuck table 20 . The top surface height gauge 82 measures the height of the back surface 102, which is the height of the top surface of the wafer 100, by contacting the back surface 102, which is the top surface of the wafer 100 held on the holding surface 22. Then, the thickness measuring device 80 calculates the thickness of the wafer 100 based on the difference between the measured value of the holding surface height gauge 81 and the measured value of the upper surface height gauge 82 .

In addition, the holding surface height gauge 81 and the upper surface height gauge 82 of the thickness measuring instrument 80 may be non-contact type height gauges.

For example, the holding surface height gauge 81 and the upper surface height gauge 82 reflect laser beam (or sound wave) reflected light ( The height of the holding surface 22 and the height of the back surface 102 of the wafer 100 may be measured based on the reflected wave).

The wafer 100 after grinding is carried out by the carrying out mechanism 172 . The transport mechanism 172 includes a suction pad 173 that suctions and holds the wafer 100 . The transfer mechanism 172 suctions and holds the wafer 100 held on the chuck table 20 by the suction pad 173 and transfers it to the spinner table 157 of the single-wafer type spinner cleaning mechanism 156 .

The spinner cleaning mechanism 156 is a spinner cleaning unit that cleans the wafer 100 ground by the grinding mechanism 70 . The spinner cleaning mechanism 156 includes a spinner table 157 that holds the wafer 100 and a nozzle 158 that blows cleaning water and dry air toward the spinner table 157 .

In the spinner cleaning mechanism 156, the spinner table 157 holding the wafer 100 is rotated, and washing water is sprayed toward the wafer 100, and the wafer 100 is spinner cleaned. Thereafter, drying air is sprayed onto the wafer 100 to dry the wafer 100 .

The wafer 100 cleaned by the spinner cleaning mechanism 156 is taken out of the spinner cleaning mechanism 156 by the robot 155 and loaded into the second cassette 163 .

Here, the configuration of the processing unit 110 described above will be described. Before holding the wafer 100 by the holding surface 22 of the chuck table 20, the processing unit 110, together with the provisional positioning mechanism 152 as a support unit, removes the upper surface of the wafer 100, the rear surface ( 102), a groove having a depth less than or equal to the depth that the grinding wheel 77 grinds is formed.

As shown in FIG. 2 , the processing unit 110 has a door-shaped column 111 installed upright on the second apparatus base 11 (see FIG. 1 ).

The door-type column 111 includes a case body 112 provided with an imaging unit 130 and a laser processing unit 135, and a temporary placement table 154 of a temporary placement mechanism 152 ( 1) is provided with an X-axis direction moving mechanism 120 that moves along the X-axis direction parallel to that of FIG.

The X-axis direction movement mechanism 120 includes a pair of X-axis guide rails 121 parallel to the X-axis direction, an X-axis movement table 123 that slides on the X-axis guide rails 121, and an X-axis guide. An X-axis ball screw 122 parallel to the rail 121, an X-axis motor 124, and an X-axis encoder 125 for detecting a rotational angle of the X-axis ball screw 122 are provided.

The X-axis moving table 123 is slidably attached to the X-axis guide rail 121 and holds the case body 112 . Moreover, the X-axis movement table 123 has a nut part not shown. An X-axis ball screw 122 is screwed to this nut portion. The X-axis motor 124 is connected to one end of the X-axis ball screw 122 .

In the X-axis direction movement mechanism 120, the X-axis motor 124 rotates the X-axis ball screw 122 so that the X-axis movement table 123 moves along the X-axis guide rail 121 in the X-axis direction. go to As a result, the case body 112 held on the X-axis movement table 123 also moves along with the X-axis movement table 123 in the X-axis direction.

The X-axis encoder 125 is rotated by the X-axis motor 124 rotating the X-axis ball screw 122, and can recognize the rotation angle of the X-axis ball screw 122. Then, the X-axis encoder 125, based on the recognition result, the position of the case body 112 moved in the X-axis direction, that is, the first camera of the reading unit 130 held in the case body 112 ( 131) and the position of the processing head 136 of the laser processing unit 135 in the X-axis direction can be detected.

As shown in FIG. 3 , the imaging unit 130 includes a cylindrical first camera 131 disposed outside the case body 112 and a ring-shaped illumination 132 provided at the tip of the first camera 131. ), and a camera housing 133 supporting the first camera 131.

The camera housing 133 is provided in the case body 112 so as to pass through a first opening 134 provided on a surface of the case body 112 on the -Y direction side. The camera housing 133 has a first camera 131 at its tip on the -Y direction side. In addition, the part on the +Y direction side in the camera housing 133 is attached to the upper surface of the Y-axis movement table 143 mentioned later.

The imaging unit 130 having such a configuration functions as a height measuring device and a warp amount calculating unit. That is, the imaging unit 130, as a height measuring instrument, measures the height of the curved outer periphery of the wafer 100 supported on the temporary placement table 154 (see FIG. 1) of the temporary placement mechanism 152 as a support unit, The height of the center (central upper surface) of the back surface 102 of the wafer 100 supported on the temporary placement table 154 is measured. In addition, the imaging unit 130 calculates a height difference, which is a difference between the measured height of the outer periphery and the height of the central upper surface, as a warp amount calculating unit. Then, the imaging unit 130 transmits the calculated height difference to the home condition determination unit 8 shown in FIG. 2 in the case body 112 . In addition, the height difference of the wafer 100 is a value according to the amount of warp of the wafer 100 .

The laser processing unit 135 held in the case body 112 together with the imaging unit 130 is placed on the back surface 102 of the wafer 100 supported on the temporary placement table 154 with respect to the wafer 100. A laser beam having an absorptive wavelength is irradiated.

The laser processing unit 135 has a processing head 136 disposed outside the case body 112 and a laser housing portion 137 supporting the processing head 136 .

The laser housing portion 137 is provided in the case body 112 so as to pass through the second opening 138 provided on the surface of the case body 112 on the -Y direction side. The laser housing portion 137 has a processing head 136 at its tip on the -Y direction side. In addition, the part on the +Y direction side in the laser housing part 137 is attached to the upper surface of the Y-axis moving table 143.

Further, in the laser processing unit 135, as shown in FIG. 4 , for example, a second camera 187 capable of capturing an image of the wafer 100 and a laser beam having an absorption wavelength with respect to the wafer 100 ( 300), a concentrator 182, a dichroic mirror 184 that guides the laser beam 300 to the concentrator 182, and an elevation that moves the concentrator 182 up and down. It has a mechanism 186.

Among these, for example, the laser oscillator 180 is disposed in the laser housing 137, the second camera 187, the dichroic mirror 184, the concentrator 182, and the lifting mechanism 186 are the processing head. (136).

Then, the laser processing unit 135 collects the laser beam 300 according to the height of the back surface 102 (upper surface height) of the wafer 100 supported on the temporary placement table 154 of the temporary placement mechanism 152 A dot is positioned to form a groove on the back surface 102 having a depth equal to or less than the depth that the grinding wheel 77 grinds with the laser beam 300 .

That is, in the laser processing unit 135, the height of the convergence point of the laser beam 300 can be adjusted by adjusting the position of the Z-axis direction in the concentrator 182 by the lifting mechanism 186. Then, in the laser processing unit 135, while adjusting the height of the converging point of the laser beam 300 so that the converging point of the laser beam 300 is disposed on the back surface 102 of the wafer 100, the laser beam is directed to the back surface 102 of the wafer 100. By irradiating, grooves are formed on the back surface 102, and the bending force of the wafer 100 is weakened.

Further, as shown in FIG. 5 , the processing head 136 in the laser processing unit 135 has a fluid ejection nozzle 191 and a fluid recovery near the distal end 139 from which the laser beam 300 is emitted. A nozzle 193 may be provided.

The fluid ejection nozzle 191 is connected to the fluid source 192 . The fluid ejection nozzle 191 is a portion of the laser beam 300 on the back surface 102 of the wafer 100 to which the fluid supplied from the fluid source 192 is irradiated, as indicated by an arrow 311. It is sprayed toward the processing point 310. The fluid is, for example, air, water, or a mixed fluid of air and water (two-fluid).

The fluid recovery nozzle 193 is connected to the suction source 194 . The fluid recovery nozzle 193 sucks the fluid from the vicinity of the processing point 310 as indicated by an arrow 312 by the suction force applied by the suction source 194 .

In the processing head 136 having such a configuration, processing debris generated by processing by the laser beam 300 can be removed from the processing point 310 by the fluid injected from the fluid spray nozzle 191 . In addition, processing scraps removed from the processing point 310 may be sucked and recovered together with the fluid by the fluid recovery nozzle 193 . Therefore, from the vicinity of the processing point 310 and the front end of the processing head 136, it is possible to remove and recover the processing waste satisfactorily. Therefore, contamination of the wafer 100 and the processing head 136 by processing debris can be suppressed.

Further, as shown in FIG. 3 , inside the case body 112, the imaging unit 130 and the laser processing unit 135 are placed on a temporary placement table 154 of the temporary placement mechanism 152 (see FIG. 1 ). A Y-axis direction moving mechanism 140 for moving along the Y-axis direction parallel to is provided.

The Y-axis direction movement mechanism 140 includes a pair of Y-axis guide rails 141 parallel to the Y-axis direction, a Y-axis movement table 143 that slides on the Y-axis guide rails 141, and a Y-axis guide. A Y-axis ball screw 142 parallel to the rail 141, a Y-axis motor 144, and a Y-axis encoder 145 for detecting the rotational angle of the Y-axis ball screw 142, and a support for holding them (146) is provided.

The Y-axis moving table 143 is slidably attached to the Y-axis guide rail 141 and holds the camera housing 133 and the laser housing part 137 therein. Moreover, the Y-axis movement table 143 has a nut part not shown. A Y-axis ball screw 142 is screwed to this nut portion. The Y-axis motor 144 is connected to one end of the Y-axis ball screw 142 .

In the Y-axis direction movement mechanism 140, the Y-axis motor 144 rotates the Y-axis ball screw 142 so that the Y-axis movement table 143 moves along the Y-axis guide rail 141 in the Y-axis direction. go to As a result, the camera housing 133 and the laser housing 137 held on the Y-axis moving table 143, the first camera 131 and the processing head 136 provided at the tips thereof are also moved along the Y-axis. It moves in the Y-axis direction together with the moving table 143.

The Y-axis encoder 145 is rotated by the Y-axis motor 144 rotating the Y-axis ball screw 142, and can recognize the rotation angle of the Y-axis ball screw 142. Then, the Y-axis encoder 145 can detect the positions in the Y-axis direction of the first camera 131 and the processing head 136 moving in the Y-axis direction based on the recognition result.

In addition, as shown in FIG. 1 , the grinding device 1 has a control unit 7 for controlling the grinding device 1 . The control unit 7 includes a CPU that performs arithmetic processing according to a control program, and a storage medium such as a memory. The control unit 7 executes various processes and collectively controls each component of the grinding device 1 .

For example, the control unit 7 controls the above-described members of the grinding device 1 to perform a grinding process on the wafer 100 .

A method of grinding the wafer 100 in the grinding device 1, which is controlled by the control unit 7, will be described below.

[Warpage measurement process]

First, the controller 7 takes out the unprocessed wafer 100 from the first cassette 161 by the robot 155 shown in FIG. It is placed on the temporary placement table 154, and the wafer 100 is supported on the temporary placement table 154 and positioned at a predetermined position.

After that, the control unit 7 rotates the rotation mechanism 151 of the temporary placement mechanism 152, the X-axis direction movement mechanism 120 (see FIG. 2) and the Y-axis direction movement mechanism in the processing unit 110 140 (see FIG. 3 ) is controlled to set the first camera 131 of the imaging unit 130 to the outer periphery of the back surface 102 of the wafer 100 supported by the provisional placement table 154. place it directly above

Then, the imaging unit 130 measures the height of the outer periphery of the back surface 102 with the first camera 131 while illuminating the back surface 102 with the illumination 132 . That is, the first camera 131 measures the height of the outer periphery of the back surface 102 by focusing on the outer periphery of the back surface 102 and obtaining the height of the focal point.

Next, the control unit 7 controls the rotation mechanism 151 of the temporary placement mechanism 152, the X-axis direction movement mechanism 120 and the Y-axis direction movement mechanism 140 in the processing unit 110 Thus, the first camera 131 of the imaging unit 130 is placed right above the center (center upper surface) of the back surface 102 of the wafer 100 supported by the provisional placement table 154 .

Then, the imaging unit 130 measures the height of the center of the back surface 102 with the first camera 131 while illuminating the back surface 102 with the illumination 132 . That is, the first camera 131 measures the height of the center of the back surface 102 by focusing on the center of the back surface 102 and obtaining the height of the focal point.

After that, the imaging unit 130 calculates a height difference, which is a difference between the measured height of the outer periphery of the back surface 102 and the height of the center of the back surface 102 . As described above, this height difference is a value according to the warp amount of the wafer 100 . The imaging unit 130 transmits the calculated height difference to the home condition determining unit 8 .

The groove condition determination unit 8 determines the number of grooves formed on the back surface 102 of the wafer 100 by the processing unit 110 based on the height difference of the back surface 102 calculated by the imaging unit 130. decide The groove condition determination unit 8 determines the amount of warp of the wafer 100 to the extent that the wafer 100 can be satisfactorily held on the holding surface 22 of the chuck table 20 by, for example, the groove formed on the back surface 102. Set the number of grooves so that they become smaller.

Alternatively, the wafer 100 held by the robot 155 may be captured by the imaging unit 130 to measure the amount of warp. At this time, the wafer 100 may be moved in the X-axis direction and the Y-axis direction by the robot 155 .

[Groove formation process]

Next, the control unit 7 controls the rotation mechanism 151 of the temporary placement mechanism 152, the X-axis direction movement mechanism 120 and the Y-axis direction movement mechanism 140 in the processing unit 110 While adjusting the position of the processing head 136 of the laser processing unit 135 with respect to the wafer 100, the laser beam 300 is irradiated from the processing head 136 toward the rear surface 102 of the wafer 100 By doing so, a plurality of parallel grooves 401 as shown in FIG. 6 are formed on the back surface 102 .

At this time, the control unit 7 adjusts the output of the laser beam 300 and the position of the light convergence point, etc., so that the depth of the groove 401 formed on the back surface 102 is adjusted using a grinding stone 77 in a grinding step described later. As a result, the depth at which the back surface 102 of the wafer 100 is ground (amount of grinding) or less is set. Further, the control unit 7 forms the grooves 401 of the number determined by the groove condition determination unit 8 on the back surface 102 of the wafer 100 .

By forming such a groove 401 on the back surface 102, the bending force in the wafer 100 is weakened, and the wafer 100 can be properly held by the holding surface 22 of the chuck table 20. The amount of warping of the wafer 100 is reduced to such an extent that it is possible.

[Maintenance process]

Next, the control unit 7 controls a table moving mechanism (not shown) to arrange the chuck table 20 shown in FIG. 1 at the work holding position on the -Y direction side. Then, the control unit 7 controls the carrying mechanism 170 to hold the wafer 100 on the provisional placement mechanism 152 so that the back surface 102 is placed on the holding surface 22 of the chuck table 20. Place it so that it rises upwards.

After that, the controller 7 controls the table moving mechanism to place the chuck table 20 at a grinding position on the +Y direction side below the grinding mechanism 70 .

[Grinding process]

Next, the control unit 7 rotates the grinding wheel 75 and the chuck table 20 of the grinding mechanism 70, and by the grinding transfer mechanism 60, the grinding mechanism including the grinding wheel 77 ( 70) is ground and fed in the -Z direction. As a result, the grinding stone 77 of the rotating grinding wheel 75 comes into contact with the back surface 102 of the wafer 100 held on the rotating chuck table 20, and grinds the back surface 102. .

In this grinding step, the controller 7 measures the thickness of the ground wafer 100 by the thickness measuring device 80 . Then, the control unit 7 performs grinding with the grinding wheel 77 until the thickness of the wafer 100 reaches a predetermined thickness. Further, as described above, the groove 401 formed on the back surface 102 of the wafer 100 has a depth equal to or less than the amount of grinding by the grinding wheel 77 . For this reason, the groove 401 disappears from the back surface 102 by this grinding step.

[Cleaning process]

After the grinding process, the control unit 7 holds the wafer 100 held on the chuck table 20 by the carrying out mechanism 172 and places it on the spinner table 157 of the spinner cleaning mechanism 156 . Then, the controller 7 cleans the wafer 100 using the spinner cleaning mechanism 156 .

After that, the control unit 7 takes out the wafer 100 from the spinner cleaning mechanism 156 using the robot 155 and carries it into the second cassette 163 on the second cassette stage 162 .

As described above, in the present embodiment, the groove 401 is formed in the wafer 100 before the holding surface 22 of the chuck table 20 holds the wafer 100, so that the wafer 100 is bent upward. weakening the power Therefore, even when the bending force of the wafer 100 is great, the holding surface 22 of the chuck table 20 can easily suction and hold the wafer 100 .

In addition, since the time required to hold the wafer 100 by the holding surface 22 can be shortened, the overall processing time of the wafer 100 by the grinding device 1 can be shortened.

In addition, in this embodiment, in order to form the groove 401 on the back surface 102 of the wafer 100, the laser beam 300 irradiated from the laser processing unit 135 is used. Therefore, unlike the configuration in which the grooves are formed with a cutting blade, the grooves 401 can be formed by dry processing without using a large amount of processing water. Therefore, since the structure for supplying and recovering processing water can be omitted or simplified, the size of the grinding device 1 can be avoided.

Further, in the present embodiment, the laser processing unit 135 forms a groove ( 401) is formed to reduce the amount of warping.

Thus, in this embodiment, since the groove|channel 401 is formed by the laser processing unit 135, the existing structure robot 155 and provisional arrangement table 154 are used. Therefore, it is possible to form the grooves 401 in the grinding device 1 without making the grinding device 1 large, because the configuration added for the formation of the grooves 401 can be reduced. .

Further, in the present embodiment, in the groove forming step, the laser processing unit 135 forms the groove 401 on the back surface 102 of the wafer 100 supported on the temporary placement table 154 . In this regard, the laser processing unit 135 may irradiate the back surface 102 of the wafer 100 held in the carrying mechanism 170 with the laser beam 300 to form the groove 401 .

Alternatively, the wafer 100 held by the robot 155 may be irradiated with the laser beam 300 to form the groove 401 and the warp amount of the wafer 100 may be reduced. At this time, the wafer 100 may be moved in the X-axis direction and the Y-axis direction with respect to the processing head 136 of the laser processing unit 135 by the robot 155 .

In the case of forming the groove 401 in the wafer 100 held in the carrying mechanism 170, the control unit 7, after the warp amount measurement step using the imaging unit 130, the suction pad of the carrying mechanism 170 In (171), the wafer 100 supported on the temporary placement table 154 is suction-held. Then, the control unit 7 disposes the wafer 100 held on the suction pad 171 below the laser processing unit 135 in the processing unit 110 .

Then, the control unit 7 controls the X-axis direction movement mechanism 120 and Y-axis direction movement mechanism 140 of the processing unit 110 and the carrying-in mechanism 170 to be held by the suction pad 171 While adjusting the position of the processing head 136 of the laser processing unit 135 with respect to the wafer 100 on which the laser beam 300 is irradiated from the processing head 136 toward the rear surface 102 of the wafer 100, , a plurality of parallel grooves 401 are formed on the back surface 102.

Moreover, in this structure, it is preferable that the carrying mechanism 170 is equipped with the suction pad 171 of a comparatively small area.

Further, the processing unit 110 including the imaging unit 130 and the laser processing unit 135 may be disposed near the spinner cleaning mechanism 156 .

In this case, the control unit 7 takes out the unprocessed wafer 100 from the first cassette 161 by the robot 155 in the warpage amount measurement step, so that the back surface 102 faces upward, and the spinner cleaning mechanism It is placed in the spinner table 157 of (156). Thereafter, the imaging unit 130 of the processing unit 110 measures the height difference of the wafer 100 and transmits it to the home condition determining unit 8 .

Then, the controller 7 forms grooves 401 on the back surface 102 of the wafer 100 supported on the spinner table 157 by means of the laser processing unit 135 . After that, the controller 7 cleans the wafer 100 by the spinner cleaning mechanism 156 .

Next, the control unit 7 uses the robot 155 to take out the cleaned wafer 100 from the spinner cleaning mechanism 156 and transfers the wafer 100 to the temporary placement mechanism 152, A holding process, a grinding process and a cleaning process are performed.

In this configuration, the wafer 100 after the formation of the grooves 401 can be easily cleaned by the spinner cleaning mechanism 156 . Accordingly, it is possible to satisfactorily remove the processing debris generated when the groove 401 is formed using the laser beam 300 from the wafer 100 .

In addition, the laser processing unit 135 may have an optical system using a galvano mirror. In this case, as shown in FIG. 7 , the laser processing unit 135 includes an oscillator 201 that oscillates a laser beam 301, an X-axis galvano mirror unit 205 that deflects the laser beam 301, and a Y An axial galvano mirror unit 210, a direction conversion mirror 215 for changing the direction of the laser beam 301, and an fθ lens 217 are provided.

In this configuration, the oscillator 201, the X-axis galvano-mirror unit 205, and the Y-axis galvano-mirror unit 210, for example, form the laser housing unit 137 of the laser processing unit 135 shown in FIG. , and the direction changing mirror 215 and the fθ lens 217 are disposed on the processing head 136 of the laser processing unit 135 .

The X-axis galvano mirror unit 205 includes an X-axis mirror 206 and an X-axis actuator 207 that adjusts the rotation angle of the X-axis mirror 206 . In the X-axis galvano mirror unit 205, by adjusting the rotation angle of the X-axis mirror 206 by the X-axis actuator 207, the optical axis of the laser beam 301 from the oscillator 201 is directed in the X-axis direction. bias

The Y-axis galvano mirror unit 210 includes a Y-axis mirror 211 and a Y-axis actuator 212 that adjusts a rotation angle of the Y-axis mirror 211 . In the Y-axis galvanomirror unit 210, by adjusting the rotation angle of the Y-axis mirror 211 by the Y-axis actuator 212, the optical axis of the laser beam 301 from the X-axis galvanomirror unit 205 is deflected in the Y-axis direction.

The direction change mirror 215 converts the direction of the laser beam 301 deflected by the X-axis galvano mirror unit 205 and the Y-axis galvano mirror unit 210 downward.

The fθ lens 217 converts the laser beam 301 deflected by the X-axis galvano mirror unit 205 and the Y-axis galvano mirror unit 210 into parallel beams having the same condensing height, so that the wafer 100 The back surface 102 of is irradiated approximately perpendicularly.

In the laser processing unit 135 having such a configuration, by adjusting the rotation angles of the X-axis mirror 206 and the Y-axis mirror 211 to adjust the deflection state of the laser beam 301 reflected by them, fθ The laser beam 301 can be irradiated to an arbitrary position on the back surface 102 of the wafer 100 located below the lens 217 .

When using the laser processing unit 135 having such a configuration, the controller 7 rotates the X-axis mirror 206 and the Y-axis mirror 211 using the X-axis actuator 207 and the Y-axis actuator 212 By adjusting the angle, the irradiation position of the laser beam 301 irradiated from the processing head 136 to the back surface 102 of the wafer 100 is controlled, and a plurality of parallel beams are formed on the back surface 102 of the wafer 100. A groove 401 may be formed.

Further, in the present embodiment, when forming the groove 401 on the back surface 102 of the wafer 100 in the groove forming step, the controller 7 includes the rotation mechanism 151 of the provisional placement mechanism 152; The position of the processing head 136 of the laser processing unit 135 is adjusted by controlling the X-axis direction movement mechanism 120 and the Y-axis direction movement mechanism 140 in the processing unit 110 . In this regard, the control unit 7 may adjust the position of the processing head 136 using only the X-axis direction movement mechanism 120 and the Y-axis direction movement mechanism 140 . Alternatively, even if the control unit 7 adjusts the position of the processing head 136 using any one of the rotation mechanism 151, the X-axis direction movement mechanism 120, and the Y-axis direction movement mechanism 140 good night.

Further, in the present embodiment, the home condition determining unit 8 calculates the height difference between the height of the outer periphery and the center of the back surface 102 of the wafer 100 calculated by the imaging unit 130. , the number of grooves formed on the back surface 102 of the wafer 100 by the processing unit 110 is determined. In this regard, the groove condition determining unit 8 may determine at least the number of grooves based on the height difference of the wafer 100 . That is, in addition to the number of grooves, the groove condition determining unit 8 may set the groove depth and/or the groove spacing based on the height difference of the wafer 100 . For example, the groove condition determining unit 8 increases the depth of the groove as the height difference of the wafer 100 increases. Further, the groove condition determination unit 8 narrows the interval between the grooves as the height difference of the wafer 100 increases.

In addition, the groove condition determining unit 8 determines the number, depth and/or spacing of grooves formed on the back surface 102 of the wafer 100 based on the height difference of the wafer 100 and the thickness of the wafer 100. may be set. In this case, the imaging unit 130 may calculate the thickness of the wafer 100 when calculating the height difference of the wafer 100 supported on the temporary placement table 154 (see FIG. 1 ). For example, the imaging unit 130 calculates the difference between the height of the center of the back surface 102 of the wafer 100 and the height of the holding surface 22 of the chuck table 20 obtained in advance, and calculates the difference , as the thickness of the wafer 100, and transmitted to the groove condition determining unit 8.

In this embodiment, the wafer 100, which is a circular plate-like work, is shown as the workpiece. In this regard, the shape of the workpiece in the present embodiment is not limited to a circular shape, and may be a polygonal shape such as a quadrangle.

Further, the grooves formed in the workpiece are not limited to a plurality of parallel straight grooves 401 as shown in Fig. 6, but a lattice-like groove may be formed. Further, when the workpiece is circular like the wafer 100, concentric or radial grooves may be formed on the workpiece.

Further, in the present embodiment, the imaging unit 130 determines a height difference, which is a difference between the height of the outer periphery and the height of the center of the back surface 102 of the wafer 100, as a value corresponding to the amount of warp of the wafer 100. are saving In this regard, the imaging unit 130 determines the height of the outer circumferential edge of the back surface 102 of the wafer 100 as a value according to the amount of warp of the wafer 100 and the pre-acquired value of the chuck table 20 The height difference of the holding surface 22 may be obtained, and the groove condition determining unit 8 may determine the number of grooves formed on the back surface 102 of the wafer 100 based on the difference. In this configuration, measurement of the height of the center of the back surface 102 of the wafer 100 can be omitted.

Further, in the present embodiment, in the warp amount measurement step, the wafer 100 placed on the temporary placement table 154 of the temporary placement mechanism 152 by the first camera 131 of the imaging unit 130 The height of the outer periphery of the back surface 102 and the height of the center are measured. In this regard, the second camera 187 of the laser processing unit 135 shown in FIG. 4 may be used to measure the height of the outer periphery and the height of the center of the back surface 102 of the wafer 100 . This second camera 187, through the dichroic mirror 184 and the concentrator 182, focuses on the outer edge and center of the back surface 102 of the wafer 100 held on the temporary placement table 154 can match

1: grinding device 7: control unit
8: home condition determining unit 10: first device base
11: second device base 12: bellows cover
13: opening 15: column
20: Chuck table 21: Porous member
22: holding surface 23: frame body
24: frame face 39: cover plate
60: grinding transfer mechanism 61: Z-axis guide rail
62: Z-axis ball screw 63: Z-axis moving table
64: Z-axis motor 65: Z-axis encoder
66: holder 70: grinding mechanism
71: spindle housing 72: spindle
73: spindle motor 74: wheel mount
75: grinding wheel 76: wheel base
77: grinding wheel 80: thickness meter
81: holding surface height gauge 82: top surface height gauge
100: wafer 101: surface
102: back side 110: processing unit
111: door type column 112: case body
120: X-axis direction movement mechanism 121: X-axis guide rail
122: X-axis ball screw 123: X-axis moving table
124: X-axis motor 125: X-axis encoder
130: imaging unit 131: first camera
132: lighting 133: camera housing
134: first opening 135: laser processing unit
136: processing head 137: laser housing
138: second opening 139: distal end
140: Y-axis direction movement mechanism 141: Y-axis guide rail
142: Y-axis ball screw 143: Y-axis moving table
144: Y-axis motor 145: Y-axis encoder
146: retainer 150: retainer member
151: rotation mechanism 152: temporary placement mechanism
153: alignment member 154: temporary placement table
155: robot 156: spinner cleaning mechanism
157: spinner table 158: nozzle
160: first cassette stage 161: first cassette
162: second cassette stage 163: second cassette
170: carrying mechanism 171: suction pad
172: take-out mechanism 173: suction pad
180: laser oscillator 182: concentrator
184: dichroic mirror 186: lifting mechanism
187: second camera 191: fluid spray nozzle
192: fluid source 193: fluid recovery nozzle
194 suction source 201 oscillator
205: X-axis galvano mirror unit 206: X-axis mirror
207: X-axis actuator 210: Y-axis galvano mirror unit
211: Y-axis mirror 212: Y-axis actuator
215: direction conversion mirror 217: fθ lens
300: laser beam 301: laser beam
310: machining point 401: groove

Claims (2)

A grinding device comprising a chuck table for sucking and holding the lower surface of a workpiece having a bending force of an outer circumferential portion by a holding surface, and a grinding mechanism for grinding the upper surface of the workpiece held by the holding surface with a grinding stone. ,
a groove forming unit for forming a groove having a depth equal to or less than a depth that the grinding wheel grinds on an upper surface of the workpiece before holding the workpiece by the holding surface;
The groove forming unit,
a support unit for supporting the workpiece;
A laser processing unit for irradiating a laser beam having an absorption wavelength with respect to the workpiece to the upper surface of the workpiece supported by the support unit.
including,
The laser processing unit positions a convergence point of a laser beam according to the height of the upper surface of the workpiece supported by the support unit, forms the groove on the upper surface of the workpiece by the laser beam, and bends the workpiece upward. A grinding device that weakens the The method of claim 1, wherein the groove forming unit comprises: a height measuring device for measuring a height of a curved outer edge of the workpiece supported by the support unit and a height of a central upper surface of the workpiece supported by the support unit; A warpage calculation unit for calculating a difference between the height of the outer circumferential edge and the height of the upper central surface measured by a height measuring device;
and a groove condition determination unit for determining at least the number of grooves based on the difference calculated by the warp amount calculation unit.