Grinding equipment

Abstract

To suction-hold a workpiece by a chuck table even when the warping force of the workpiece is large.SOLUTION: Before a holding surface 22 of a chuck table 20 holds a wafer 100, a groove is formed on the wafer 100 and the warping force of the wafer 100 is weakened. Therefore, even when the warping force of the wafer 100 is large, the wafer 100 can be easily suction-held by the holding surface 22 of the chuck table 20. Also, since the time required by the holding surface 22 to hold the wafer 100 can be shortened, the entire processing time of the wafer 100 by a grinding device 1 can be shortened.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a grinding device. [Background technology]

[0002] When a plate-shaped workpiece, the outer periphery of which has a tendency to warp upward, is sucked and held by a holding surface and ground with a grinding wheel, the outer periphery of the workpiece may lift up from the holding surface, causing the workpiece to be torn off from the holding surface by the grinding wheel. For this reason, the technology in Patent Document 1 weakens the warping force by forming cutting grooves with a cutting blade on the top surface of the workpiece held by the holding surface, which will be the surface to be ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-223667 Summary of the Invention [Problem to be solved by the invention]

[0004] When forming the above-mentioned grooves, cutting chips generated during cutting are discharged using cutting water. Therefore, the grooves are formed in a machining chamber while the workpiece is held by a chuck table. Therefore, if the workpiece is significantly warped and it is difficult to hold the workpiece by suction using the chuck table, it becomes difficult to form the grooves and perform the grinding process on the workpiece.

[0005] Therefore, an object of the present invention is to weaken the warping force when grinding a workpiece having a warping force at its outer periphery, and to hold the workpiece by suction using a chuck table. [Means for solving the problem]

[0006] The grinding device of the present invention (the present grinding device) is a grinding device comprising: a chuck table that uses a holding surface to suction-hold the underside of a workpiece having an outer periphery that has a force that causes the outer periphery to warp up; and a grinding mechanism that uses a grinding wheel to grind the upper surface of the workpiece held by the holding surface. The grinding device comprises a groove forming unit that forms a groove in the upper surface of the workpiece to a depth equal to or less than the depth to be ground by the grinding wheel before the workpiece is held by the holding surface, the groove forming unit comprising: a support unit that supports the workpiece; and a laser processing unit that irradiates the upper surface of the workpiece supported by the support unit with a laser beam having a wavelength that is absorbed by the workpiece. a height measuring device that measures the height of the warped outer periphery of the workpiece supported by the support unit and the height of the central upper surface of the workpiece supported by the support unit, and a warpage amount calculating unit that calculates the difference between the height of the outer periphery and the height of the central upper surface measured by the height measuring device; Equipped with a groove condition determination unit that determines at least the number of grooves based on the difference calculated by the warpage amount calculation unit, The laser processing unit positions the focal point of the laser beam according to the height of the top surface of the workpiece supported by the support unit, and forms the groove on the top surface of the workpiece using the laser beam, thereby weakening the force that causes the workpiece to warp up. [Effects of the Invention]

[0007] In this grinding machine, before the holding surface of the chuck table holds the workpiece, the groove forming unit forms grooves in the workpiece to weaken the warping force of the workpiece.As a result, even when the warping force of the workpiece is large, the holding surface of the chuck table can easily suction and hold the workpiece. Furthermore, since the time required for holding the workpiece by the holding surface can be reduced, the overall processing time for the workpiece by this grinding device can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a configuration of a grinding device according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing the configuration of a processing unit. [Figure 3] 10 is an explanatory diagram showing the configuration of a Y-axis direction movement mechanism in the processing unit. FIG. [Figure 4] FIG. 2 is an explanatory diagram showing a configuration example of a laser processing unit. [Figure 5]FIG. 2 is an explanatory diagram showing an example of the configuration of a processing head in the laser processing unit. [Figure 6] 1A and 1B are explanatory views showing examples of grooves formed on the rear surface of a wafer. [Figure 7] FIG. 10 is an explanatory diagram showing another configuration example of the laser processing unit. DETAILED DESCRIPTION OF THE INVENTION

[0009] As shown in FIG. 1, the grinding apparatus 1 according to this embodiment is an apparatus for grinding a wafer 100 as a workpiece. The wafer 100 is, for example, a circular, plate-shaped workpiece, and has a front surface 101 and a back surface 102. A device (not shown) is formed on the front surface 101 of the wafer 100, and a protective tape 103 is attached to the front surface 101. The back surface 102 of the wafer 100 is the surface to be processed and subjected to the grinding process. In addition, the wafer 100 has a force that causes the outer periphery thereof to warp up. That is, the outer periphery (outer periphery) of the wafer 100 warps up toward the back surface 102, which is the upper surface of the wafer 100, as shown in FIG. 4.

[0010] The grinding device 1 has a first device base 10 and a second device base 11 disposed behind the first device base 10 (on the +Y direction side).

[0011] A first cassette stage 160 and a second cassette stage 162 are provided on the front side (-Y direction side) of the first equipment base 10. A first cassette 161 that stores unprocessed wafers 100 is placed on the first cassette stage 160. A second cassette 163 that stores processed wafers 100 is placed on the second cassette stage 162.

[0012] The first cassette 161 and the second cassette 163 each have a plurality of shelves therein, and each shelf accommodates one wafer 100. That is, the first cassette 161 and the second cassette 163 accommodate a plurality of wafers 100 in a shelf-like manner.

[0013] 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 that holds the wafer 100. The robot 155 carries (stores) the processed wafer 100 into the second cassette 163. The robot 155 also removes the unprocessed wafer 100 from the first cassette 161 and places it on the temporary placement table 154 of the temporary placement mechanism 152.

[0014] 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 has a temporary placement table 154 for supporting the wafer 100, an alignment member 153 for aligning the wafer, and a rotation mechanism 151 for rotating the temporary placement table 154.

[0015] The alignment member 153 includes a plurality of alignment pins arranged on the outside so as to surround the temporary placement table 154, and a slider that moves the alignment pins in the radial direction of the temporary placement table 154. In the alignment member 153, the alignment pins are moved toward the center in the radial direction of the temporary placement table 154, thereby reducing the diameter of a circle connecting the plurality of alignment pins. As a result, the wafer 100 supported on the temporary placement table 154 is aligned (centered) at a predetermined position. This temporary placement mechanism 152 (temporary placement table 154) functions as a support unit that supports the wafer 100.

[0016] A processing unit 110 is provided on the +Y direction side of the temporary placement mechanism 152. This processing unit 110 and the temporary placement mechanism 152 as the support unit described above are included in the groove forming unit in this embodiment. The processing unit 110 will be described later.

[0017] Furthermore, a carry-in mechanism 170 is provided at a position adjacent to the temporary placement mechanism 152. The carry-in mechanism 170 has a suction pad 171 that suction-holds the wafer 100. The carry-in mechanism 170 suction-holds the wafer 100, which has been taken out by the robot 155 and temporarily placed on the temporary placement table 154, using the suction pad 171, and places the wafer 100 on the holding surface 22 of the chuck table 20. In this way, the carry-in mechanism 170 transports the wafer 100 held by the robot 155 to the chuck table 20.

[0018] An opening 13 is provided on the upper surface side of the second apparatus base 11. In the opening 13, a chuck table 20 having a holding surface 22 for holding the wafer 100 is disposed.

[0019] The chuck table 20 includes a porous member 21 and a frame 23 that houses 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 is connected to a suction source (not shown) to hold the front surface 101 of the wafer 100 by suction. That is, the chuck table 20 holds the front surface 101, which is the lower surface of the wafer 100, by means of the holding surface 22. Furthermore, a frame surface 24, which is the upper surface of the frame 23, surrounds the holding surface 22 and is formed to be flush with the holding surface 22.

[0020] The chuck table 20 can be rotated around a rotation axis passing through the center of the holding surface 22 while holding the wafer 100 on the holding surface 22 by a table rotation mechanism (not shown) provided below the chuck table 20.

[0021] Furthermore, 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 is moved along the Y-axis direction between a workpiece placement position on the -Y direction side for holding the wafer 100 on the holding surface 22 and a grinding position on the +Y direction side where the wafer 100 held on the holding surface 22 is ground.

[0022] A cover plate 39 is provided around the periphery of the chuck table 20 and moves in the Y-axis direction together with the chuck table 20. In addition, a bellows cover 12 that expands and contracts in the Y-axis direction is connected to the cover plate 39.

[0023] Furthermore, a column 15 is erected on the +Y direction side of the second apparatus base 11. In front of the column 15, a grinding mechanism 70 for grinding the wafer 100 and a grinding feed mechanism 60 are provided.

[0024] The grinding feed mechanism 60 moves the chuck table 20 and the grinding wheel 77 of the grinding mechanism 70 relatively in the Z-axis direction (grinding feed direction) perpendicular to the holding surface 22. In this embodiment, the grinding feed mechanism 60 is configured to move the grinding wheel 77 in the Z-axis direction relative to the chuck table 20.

[0025] The grinding feed 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, a Z-axis ball screw 62 parallel to the Z-axis guide rails 61, a Z-axis motor 64, a Z-axis encoder 65 for detecting the rotation angle of the Z-axis ball screw 62, and a holder 66 attached to the Z-axis moving table 63. The holder 66 supports the grinding mechanism 70.

[0026] The Z-axis moving table 63 is slidably installed on the Z-axis guide rail 61. A nut portion (not shown) is fixed to the Z-axis moving table 63. A Z-axis ball screw 62 is threadedly engaged with this nut portion. A Z-axis motor 64 is connected to one end of the Z-axis ball screw 62.

[0027] In the grinding feed mechanism 60, the Z-axis motor 64 rotates the Z-axis ball screw 62, causing the Z-axis moving table 63 to move in the Z-axis direction along the Z-axis guide rail 61. As a result, the holder 66 attached to the Z-axis moving table 63 and the grinding mechanism 70 supported by the holder 66 also move in the Z-axis direction together with the Z-axis moving table 63.

[0028] Z-axis encoder 65 is rotated by Z-axis motor 64 rotating Z-axis ball screw 62, and can recognize the rotation angle of Z-axis ball screw 62. Based on the recognition result, Z-axis encoder 65 can detect the height position of grinding wheel 77 of grinding mechanism 70, which is moved in the Z-axis direction.

[0029] The grinding mechanism 70 grinds the back surface 102, which is the upper surface of the wafer 100 held by the chuck table 20, with a grinding wheel 77. The grinding mechanism 70 includes a spindle housing 71 fixed to the holder 66, a spindle 72 rotatably held by the spindle housing 71, a spindle motor 73 that rotates and drives the spindle 72, a wheel mount 74 attached to the lower end of the spindle 72, and a grinding wheel 75 supported by the wheel mount 74.

[0030] 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 perpendicular to the holding surface 22 of the chuck table 20, and is rotatably supported by the spindle housing 71.

[0031] The spindle motor 73 is connected to the upper end side of the spindle 72. The spindle motor 73 rotates the spindle 72 about a rotation axis extending in the Z-axis direction.

[0032] The wheel mount 74 is formed in a disk shape and is fixed to the lower end (tip) of the spindle 72. The wheel mount 74 supports the grinding wheel 75.

[0033] The grinding wheel 75 is formed so that its outer diameter is approximately the same as the outer diameter of the wheel mount 74. The grinding wheel 75 includes an annular wheel base 76 made of a metal material. A plurality of grinding stones 77 arranged in an annular shape are fixed to the underside of the wheel base 76 around the entire circumference. The grinding stones 77 are rotated around their center by the spindle motor 73 together with the spindle 72, and grind the back surface 102 of the wafer 100 held on the chuck table 20.

[0034] As shown in FIG. 1, a thickness measuring device 80 is disposed on the side of the opening 13 in the second device base 11.

[0035] The thickness measuring device 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 23, which is the same surface as the holding surface 22 of the chuck table 20. The upper surface height gauge 82 measures the height of the back surface 102, which is the height of the upper surface of the wafer 100, by contacting the back surface 102, which is the upper surface of the wafer 100 held on the holding surface 22. The thickness measuring device 80 then calculates the thickness of the wafer 100 based on the difference between the measurement value of the holding surface height gauge 81 and the measurement value of the upper surface height gauge 82.

[0036] The holding surface height gauge 81 and the upper surface height gauge 82 of the thickness measuring device 80 may be non-contact height gauges. For example, the holding surface height gauge 81 and the upper surface height gauge 82 may be configured to measure the height of the holding surface 22 and the height of the back surface 102 of the wafer 100 based on the reflected light (reflected wave) of a laser beam (or sound wave) irradiated onto the frame surface 24 of the frame 23 and the back surface 102 of the wafer 100.

[0037] The ground wafer 100 is carried out by a carry-out mechanism 172. The carry-out mechanism 172 is provided with a suction pad 173 that suction-holds the wafer 100. The carry-out mechanism 172 suction-holds the wafer 100 held on the chuck table 20 by the suction pad 173, and transports the wafer 100 to a spinner table 157 of a single-wafer spinner cleaning mechanism 156.

[0038] 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 sprays cleaning water and dry air toward the spinner table 157.

[0039] In the spinner cleaning mechanism 156, a spinner table 157 holding the wafer 100 rotates, and cleaning water is sprayed toward the wafer 100, thereby spinner-cleaning the wafer 100. Dry air is then blown onto the wafer 100, thereby drying the wafer 100.

[0040] The wafer 100 cleaned by the spinner cleaning mechanism 156 is carried out of the spinner cleaning mechanism 156 by the robot 155 and carried into the second cassette 163 .

[0041] Here, we will explain the configuration of the above-mentioned processing unit 110. The processing unit 110, together with the temporary placement mechanism 152 as a support unit, forms a groove in the back surface 102, which is the upper surface of the wafer 100, to a depth equal to or less than the depth to be ground by the grinding wheel 77, before holding the wafer 100 on the holding surface 22 of the chuck table 20. As shown in FIG. 2, the processing unit 110 has a gate-type column 111 that is erected on the second device base 11 (see FIG. 1).

[0042] The portal column 111 includes a housing 112 equipped with an imaging unit 130 and a laser processing unit 135, and an X-axis direction moving mechanism 120 that moves the housing 112 along the X-axis direction parallel to the temporary placement table 154 of the temporary placement mechanism 152 (see Figure 1).

[0043] 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, an X-axis ball screw 122 parallel to the X-axis guide rails 121, an X-axis motor 124, and an X-axis encoder 125 for detecting the rotation angle of the X-axis ball screw 122.

[0044] X-axis moving table 123 is slidably installed on X-axis guide rail 121, and holds housing 112. X-axis moving table 123 also has a nut portion (not shown). X-axis ball screw 122 is threadedly engaged with this nut portion. X-axis motor 124 is connected to one end of X-axis ball screw 122.

[0045] In X-axis direction movement mechanism 120, X-axis motor 124 rotates X-axis ball screw 122, causing X-axis movement table 123 to move in the X-axis direction along X-axis guide rail 121. As a result, housing 112 held by X-axis movement table 123 also moves in the X-axis direction together with X-axis movement table 123.

[0046] X-axis encoder 125 is rotated by X-axis motor 124 rotating X-axis ball screw 122, and can recognize the rotation angle of X-axis ball screw 122. Then, based on the recognition result, X-axis encoder 125 can detect the position of housing 112 that is moved in the X-axis direction, that is, the positions in the X-axis direction of first camera 131 of imaging unit 130 and processing head 136 of laser processing unit 135 that are held in housing 112.

[0047] As shown in FIG. 3, the imaging unit 130 has a cylindrical first camera 131 arranged outside the housing 112, a ring-shaped light 132 provided at the tip of the first camera 131, and a camera housing 133 that supports the first camera 131.

[0048] Camera housing 133 is provided in housing 112 so as to pass through first opening 134 provided in the surface on the −Y direction side of housing 112. Camera housing 133 has first camera 131 at its tip on the −Y direction side. In addition, the portion of camera housing 133 on the +Y direction side is attached to the upper surface of Y-axis moving table 143, which will be described later.

[0049] The imaging unit 130 having such a configuration functions as a height measuring device and a warpage calculation unit. That is, as a height measuring device, the imaging unit 130 measures the height of the warped outer periphery of the wafer 100 supported on the temporary placement table 154 (see FIG. 1) of the temporary placement mechanism 152 serving as a support unit, and the height of the center (central upper surface) of the back surface 102 of the wafer 100 supported on the temporary placement table 154. Furthermore, the imaging unit 130 calculates the height difference, which is the difference between the measured height of the outer periphery and the height of the central upper surface, as a warpage calculation unit. Then, the imaging unit 130 transmits the calculated height difference to the groove condition determination unit 8 shown in FIG. 2 in the housing 112. The height difference of the wafer 100 is a value corresponding to the amount of warpage of the wafer 100.

[0050] The laser processing unit 135 held in the housing 112 together with the imaging unit 130 irradiates the back surface 102 of the wafer 100 supported on the temporary placement table 154 with a laser beam having a wavelength absorbable by the wafer 100 . The laser processing unit 135 has a processing head 136 disposed outside the housing 112 and a laser housing portion 137 that supports the processing head 136 .

[0051] The laser housing unit 137 is provided in the housing 112 so as to pass through a second opening 138 provided in the surface on the −Y direction side of the housing 112. The laser housing unit 137 has a processing head 136 at its tip on the −Y direction side. In addition, the portion of the laser housing unit 137 on the +Y direction side is attached to the upper surface of the Y-axis moving table 143.

[0052] The laser processing unit 135 also includes, for example, as shown in FIG. 4, a second camera 187 capable of capturing an image of the wafer 100, a laser oscillator 180 that emits a laser beam 300 having a wavelength that is absorbed by the wafer 100, a condenser 182, a dichroic mirror 184 that directs the laser beam 300 to the condenser 182, and an elevating mechanism 186 that moves the condenser 182 up and down.

[0053] Of these, for example, the laser oscillator 180 is disposed in the laser housing portion 137 , and the second camera 187 , the dichroic mirror 184 , the condenser 182 and the lifting mechanism 186 are disposed in the processing head 136 .

[0054] Then, the laser processing unit 135 positions the focal point of the laser beam 300 according to the height (top surface height) of the back surface 102 of the wafer 100 supported on the temporary placement table 154 of the temporary placement mechanism 152, and forms a groove on the back surface 102 using the laser beam 300, the groove having a depth equal to or less than the depth to be ground by the grinding wheel 77.

[0055] That is, in the laser processing unit 135, the height of the focal point of the laser beam 300 can be adjusted by adjusting the position of the condenser 182 in the Z-axis direction using the lifting mechanism 186. Then, in the laser processing unit 135, the height of the focal point of the laser beam 300 is adjusted so that the focal point is located on the back surface 102 of the wafer 100, and the laser beam is irradiated onto the back surface 102 of the wafer 100, thereby forming a groove on the back surface 102 and weakening the force that causes the wafer 100 to warp up.

[0056] As shown in FIG. 5, the processing head 136 in the laser processing unit 135 may have a fluid ejection nozzle 191 and a fluid recovery nozzle 193 near the tip 139 from which the laser beam 300 is emitted.

[0057] The fluid injection nozzle 191 is connected to a fluid source 192. The fluid injection nozzle 191 injects the fluid supplied from the fluid source 192 toward a processing point 310, which is a portion on the back surface 102 of the wafer 100 that is irradiated with a laser beam 300, as indicated by an arrow 311. The fluid is, for example, air, water, or a mixed fluid of air and water (two-fluid).

[0058] The fluid recovery nozzle 193 is connected to a suction source 194. The fluid recovery nozzle 193 sucks fluid from the vicinity of the processing point 310 by the suction force applied by the suction source 194, as shown by arrow 312.

[0059] In the processing head 136 having such a configuration, processing debris generated by processing with the laser beam 300 can be removed from the processing point 310 by the fluid ejected from the fluid ejection nozzle 191. Furthermore, the processing debris removed from the processing point 310 can be collected together with the fluid by suction using the fluid recovery nozzle 193. Therefore, it is possible to effectively remove and collect processing debris from the vicinity of the processing point 310 and the tip of the processing head 136. Therefore, it is possible to prevent the wafer 100 and the processing head 136 from being contaminated by processing debris.

[0060] As shown in FIG. 3, the housing 112 is provided with a Y-axis direction moving mechanism 140 for moving the imaging unit 130 and the laser processing unit 135 along the Y-axis direction parallel to the temporary placement table 154 (see FIG. 1) of the temporary placement mechanism 152.

[0061] The Y-axis direction moving mechanism 140 includes a pair of Y-axis guide rails 141 parallel to the Y-axis direction, a Y-axis moving table 143 that slides on these Y-axis guide rails 141, a Y-axis ball screw 142 parallel to the Y-axis guide rails 141, a Y-axis motor 144, a Y-axis encoder 145 for detecting the rotation angle of the Y-axis ball screw 142, and a holding table 146 that holds these.

[0062] Y-axis moving table 143 is slidably installed on Y-axis guide rail 141, and holds camera housing 133 and laser housing 137. Y-axis moving table 143 also has a nut portion (not shown). Y-axis ball screw 142 is threadedly engaged with this nut portion. Y-axis motor 144 is connected to one end of Y-axis ball screw 142.

[0063] In the Y-axis direction moving mechanism 140, the Y-axis motor 144 rotates the Y-axis ball screw 142, causing the Y-axis moving table 143 to move in the Y-axis direction along the Y-axis guide rail 141. As a result, the camera housing 133 and laser housing part 137 held by the Y-axis moving table 143, as well as the first camera 131 and processing head 136 provided at the tip of these, also move in the Y-axis direction together with the Y-axis moving table 143.

[0064] 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. Based on the recognition result, the Y-axis encoder 145 can detect the positions in the Y-axis direction of the first camera 131 and the processing head 136, which are moved in the Y-axis direction.

[0065] 1, the grinding apparatus 1 has a control unit 7 for controlling the grinding apparatus 1. The control unit 7 includes a CPU that performs calculations according to a control program, and a storage medium such as a memory. The control unit 7 executes various processes and controls each component of the grinding apparatus 1. For example, the control unit 7 controls the above-mentioned components of the grinding device 1 to perform the grinding process on the wafer 100.

[0066] The method for grinding the wafer 100 in the grinding apparatus 1, which is controlled by the control unit 7, will be described below.

[0067] [Warp amount measurement process] First, the control unit 7 causes the robot 155 shown in FIG. 1 to take out the unprocessed wafer 100 from the first cassette 161, place it on the temporary placement table 154 of the temporary placement mechanism 152 with the back surface 102 facing upward, and supports the wafer 100 on the temporary placement table 154, aligning it to a predetermined position.

[0068] Then, the control unit 7 controls the rotation mechanism 151 of the temporary placement mechanism 152, as well as the X-axis direction moving mechanism 120 (see Figure 2) and the Y-axis direction moving mechanism 140 (see Figure 3) in the processing unit 110, to position the first camera 131 of the imaging unit 130 directly above the outer edge of the back surface 102 of the wafer 100 supported by the temporary placement table 154.

[0069] Then, imaging unit 130 measures the height of the outer periphery of back surface 102 with first camera 131 while illuminating back surface 102 with illumination 132. That is, first camera 131 focuses on the outer periphery of back surface 102 and measures the height of the focal point, thereby measuring the height of the outer periphery of back surface 102.

[0070] Next, the control unit 7 controls the rotation mechanism 151 of the temporary placement mechanism 152, as well as the X-axis direction moving mechanism 120 and the Y-axis direction moving mechanism 140 in the processing unit 110, to position the first camera 131 of the imaging unit 130 directly above the center (central upper surface) of the back surface 102 of the wafer 100 supported by the temporary placement table 154.

[0071] 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 light 132. That is, the first camera 131 focuses on the center of the back surface 102 and measures the height of the center of the back surface 102 by finding the height of this focus.

[0072] Thereafter, the imaging unit 130 calculates the height difference, which is the 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 amount of warpage of the wafer 100. The imaging unit 130 transmits the calculated height difference to the groove condition determination unit 8.

[0073] The groove condition determination unit 8 determines the number of grooves to be 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. The groove condition determination unit 8 sets the number of grooves so that the amount of warpage of the wafer 100 is small enough to allow the wafer 100 to be well held on the holding surface 22 of the chuck table 20 by the grooves formed on the back surface 102, for example. The amount of warpage may be measured by capturing an image of the wafer 100 held by the robot 155 using the imaging unit 130. At this time, the robot 155 may move the wafer 100 in the X-axis direction and the Y-axis direction.

[0074] [Groove formation process] Next, the control unit 7 controls the rotation mechanism 151 of the temporary placement mechanism 152, and the X-axis direction moving mechanism 120 and the Y-axis direction moving mechanism 140 in the processing unit 110 to adjust the position of the processing head 136 of the laser processing unit 135 relative to the wafer 100, and irradiates a laser beam 300 from the processing head 136 toward the back surface 102 of the wafer 100, thereby forming multiple parallel grooves 401 on the back surface 102 as shown in Figure 6.

[0075] At this time, the control unit 7 adjusts the output of the laser beam 300, the position of the focal point, etc., so that the depth of the grooves 401 formed on the back surface 102 is equal to or less than the depth (grinding amount) to which the back surface 102 of the wafer 100 is ground by the grinding wheel 77 in the grinding step described below. Also, the control unit 7 forms the number of grooves 401 determined by the groove condition determination unit 8 on the back surface 102 of the wafer 100.

[0076] By forming such grooves 401 on the back surface 102, the force of the wafer 100 warping up is weakened, and the amount of warping of the wafer 100 is reduced to an extent that the wafer 100 can be held well by the holding surface 22 of the chuck table 20.

[0077] [Holding process] 1 at the workpiece holding position on the -Y direction side by controlling the table moving mechanism (not shown). Then, the control unit 7 controls the carry-in mechanism 170 to hold the wafer 100 on the temporary placement mechanism 152 and place it on the holding surface 22 of the chuck table 20 with the back surface 102 facing upward. Thereafter, the control unit 7 controls the table moving mechanism to place the chuck table 20 at a grinding position below the grinding mechanism 70 on the +Y direction side.

[0078] [Grinding process] Next, the control unit 7 rotates the grinding wheel 75 and chuck table 20 of the grinding mechanism 70, and causes the grinding mechanism 70, including the grinding stone 77, to be fed in the -Z direction by the grinding feed mechanism 60. 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 this back surface 102.

[0079] In this grinding step, the control unit 7 measures the thickness of the wafer 100 being ground using the thickness measuring device 80. Then, the control unit 7 continues grinding with the grinding wheel 77 until the thickness of the wafer 100 reaches a predetermined thickness that has been set in advance. As described above, the grooves 401 formed on the back surface 102 of the wafer 100 have a depth equal to or less than the amount of grinding by the grinding wheel 77. Therefore, the grooves 401 disappear from the back surface 102 as a result of this grinding step.

[0080] [Cleaning process] After the grinding process, the control unit 7 controls the unloading mechanism 172 to hold the wafer 100 held on the chuck table 20 and place it on the spinner table 157 of the spinner cleaning mechanism 156. Then, the control unit 7 cleans the wafer 100 using the spinner cleaning mechanism 156.

[0081] Thereafter, the control unit 7 causes the robot 155 to remove the wafer 100 from the spinner cleaning mechanism 156 and load it into the second cassette 163 on the second cassette stage 162.

[0082] As described above, in this embodiment, before the holding surface 22 of the chuck table 20 holds the wafer 100, the grooves 401 are formed in the wafer 100 to weaken the warping force of the wafer 100. Therefore, even when the warping force of the wafer 100 is large, the holding surface 22 of the chuck table 20 can easily hold the wafer 100 by suction. Furthermore, since the time required for the holding surface 22 to hold the wafer 100 can be shortened, the overall processing time for the wafer 100 by the grinding apparatus 1 can be shortened.

[0083] Furthermore, in this embodiment, the laser beam 300 emitted from the laser processing unit 135 is used to form the grooves 401 on the back surface 102 of the wafer 100. Therefore, unlike a configuration in which a groove is formed using a cutting blade, the grooves 401 can be formed by dry processing that does not use a large amount of processing water. Therefore, the configuration for supplying and recovering processing water can be omitted or simplified, and the grinding apparatus 1 can be prevented from becoming larger.

[0084] In this embodiment, the wafer 100 is transported to the temporary placement table 154 by the robot 155 and supported by the temporary placement table 154, and grooves 401 are formed in the wafer 100 by the laser processing unit 135 to reduce the amount of warpage.

[0085] As described above, in this embodiment, the existing components of the robot 155 and temporary placement table 154 are used to form the groove 401 by the laser processing unit 135. Therefore, the components added to form the groove 401 can be reduced, and the groove 401 can be formed within the grinding apparatus 1 without increasing the size of the grinding apparatus 1.

[0086] In this 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 form the groove 401 by irradiating the back surface 102 of the wafer 100 held by the carry-in mechanism 170 with a laser beam 300. Alternatively, the wafer 100 held by the robot 155 may be irradiated with a laser beam 300 to form grooves 401, thereby reducing the amount of warpage of the wafer 100. At this time, the robot 155 may move the wafer 100 in the X-axis direction and the Y-axis direction relative to the processing head 136 of the laser processing unit 135.

[0087] When forming the grooves 401 in the wafer 100 held by the carry-in mechanism 170, after the warpage amount measurement step using the imaging unit 130, the control unit 7 causes the suction pad 171 of the carry-in mechanism 170 to suction and hold the wafer 100 supported on the temporary placement table 154. Then, the control unit 7 places the wafer 100 held by the suction pad 171 below the laser processing unit 135 in the processing unit 110.

[0088] The control unit 7 then controls the X-axis direction moving mechanism 120 and Y-axis direction moving mechanism 140 of the processing unit 110, as well as the loading mechanism 170, to adjust the position of the processing head 136 of the laser processing unit 135 relative to the wafer 100 held on the suction pad 171, and irradiates a laser beam 300 from the processing head 136 toward the back surface 102 of the wafer 100, thereby forming multiple parallel grooves 401 on the back surface 102. In this configuration, it is preferable that the carry-in mechanism 170 is provided with a suction pad 171 having a relatively small area.

[0089] Furthermore, 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, in the warpage amount measurement step, the control unit 7 causes the robot 155 to take out the unprocessed wafer 100 from the first cassette 161 and place it on the spinner table 157 of the spinner cleaning mechanism 156 with the back surface 102 facing upward. Thereafter, the imaging unit 130 of the processing unit 110 measures the height difference of the wafer 100 and transmits the result to the groove condition determination unit 8.

[0090] Then, the control unit 7 causes the laser processing unit 135 to form the grooves 401 on the back surface 102 of the wafer 100 supported on the spinner table 157. Thereafter, the control unit 7 causes the spinner cleaning mechanism 156 to clean the wafer 100.

[0091] Next, the control unit 7 uses the robot 155 to remove the cleaned wafer 100 from the spinner cleaning mechanism 156, and transports the wafer 100 to the temporary placement mechanism 152, where the holding step, grinding step, and cleaning step described above are performed.

[0092] In this configuration, the wafer 100 after the formation of the grooves 401 can be easily cleaned by the spinner cleaning mechanism 156. Therefore, it is possible to effectively remove from the wafer 100 processing debris generated when the grooves 401 are formed using the laser beam 300.

[0093] 7, the laser processing unit 135 may have an optical system using a galvanometer mirror. In this case, the laser processing unit 135 includes an oscillator 201 that oscillates a laser beam 301, an X-axis galvanometer mirror section 205 and a Y-axis galvanometer mirror section 210 that deflect the laser beam 301, a direction-changing mirror 215 that changes the direction of the laser beam 301, and an fθ lens 217.

[0094] In this configuration, for example, the oscillator 201, the X-axis galvanometer mirror section 205, and the Y-axis galvanometer mirror section 210 are arranged in the laser housing section 137 of the laser processing unit 135 shown in Figure 3, and the direction conversion mirror 215 and the fθ lens 217 are arranged in the processing head 136 of the laser processing unit 135.

[0095] X-axis galvanometer mirror section 205 includes X-axis mirror 206 and X-axis actuator 207 that adjusts the rotation angle of X-axis mirror 206. In X-axis galvanometer mirror section 205, the rotation angle of X-axis mirror 206 is adjusted by X-axis actuator 207, thereby deflecting the optical axis of laser beam 301 from oscillator 201 in the X-axis direction.

[0096] Y-axis galvanometer mirror section 210 includes Y-axis mirror 211 and Y-axis actuator 212 that adjusts the rotation angle of Y-axis mirror 211. In Y-axis galvanometer mirror section 210, the rotation angle of Y-axis mirror 211 is adjusted by Y-axis actuator 212, thereby deflecting the optical axis of laser beam 301 from X-axis galvanometer mirror section 205 in the Y-axis direction.

[0097] The direction-changing mirror 215 changes the direction of the laser beam 301 deflected by the X-axis galvanometer mirror section 205 and the Y-axis galvanometer mirror section 210 downward. The fθ lens 217 converts the laser beam 301 deflected by the X-axis galvanometer mirror section 205 and the Y-axis galvanometer mirror section 210 into parallel beams of equal condensed height, and irradiates the rear surface 102 of the wafer 100 substantially perpendicularly.

[0098] 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 and thereby adjusting the deflection state of the laser beam 301 reflected by them, the laser beam 301 can be irradiated to any position on the back surface 102 of the wafer 100 located below the fθ lens 217.

[0099] When using a laser processing unit 135 configured in this manner, the control unit 7 can control the irradiation position of the laser beam 301 irradiated from the processing head 136 onto the back surface 102 of the wafer 100 by adjusting the rotation angles of the X-axis mirror 206 and the Y-axis mirror 211 using the X-axis actuator 207 and the Y-axis actuator 212, thereby forming multiple parallel grooves 401 on the back surface 102 of the wafer 100.

[0100] Furthermore, in this embodiment, when forming the grooves 401 on the back surface 102 of the wafer 100 in the groove forming step, the control unit 7 controls the rotation mechanism 151 of the temporary placement mechanism 152 and the X-axis direction moving mechanism 120 and the Y-axis direction moving mechanism 140 in the processing unit 110 to adjust the position of the processing head 136 of the laser processing unit 135. In this regard, the control unit 7 may adjust the position of the processing head 136 using only the X-axis direction moving mechanism 120 and the Y-axis direction moving mechanism 140. Alternatively, the control unit 7 may adjust the position of the processing head 136 using either the rotation mechanism 151 or the X-axis direction moving mechanism 120 or the Y-axis direction moving mechanism 140.

[0101] Furthermore, in this embodiment, the groove condition determination unit 8 determines the number of grooves to be formed on the back surface 102 of the wafer 100 by the processing unit 110 based on the elevation difference, which is the difference between the height of the outer periphery and the height of the center on the back surface 102 of the wafer 100 calculated by the imaging unit 130. In this regard, the groove condition determination unit 8 only needs to determine at least the number of grooves based on the elevation difference of the wafer 100. That is, the groove condition determination unit 8 may set the groove depth and / or groove spacing in addition to the number of grooves based on the elevation difference of the wafer 100. For example, the groove condition determination unit 8 increases the groove depth as the elevation difference of the wafer 100 increases. Furthermore, the groove condition determination unit 8 decreases the groove spacing as the elevation difference of the wafer 100 increases.

[0102] Furthermore, the groove condition determination unit 8 may set the number, depth, and / or spacing of grooves to be formed on the back surface 102 of the wafer 100 based on the thickness of the wafer 100 as well as the height difference of the wafer 100. 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, which has been acquired in advance, and transmits this difference to the groove condition determination unit 8 as the thickness of the wafer 100.

[0103] In this embodiment, the workpiece is a wafer 100, which is a circular plate-like workpiece. In this regard, the shape of the workpiece in this embodiment is not limited to a circle, and may be a polygon such as a square.

[0104] Furthermore, the grooves formed in the workpiece are not limited to the multiple parallel linear grooves 401 shown in Fig. 6, but may be formed in a grid pattern. Furthermore, when the workpiece is circular, such as the wafer 100, concentric or radial grooves may be formed in the workpiece.

[0105] Furthermore, in this embodiment, the imaging unit 130 obtains the height difference, which is the 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 warpage of the wafer 100. In this regard, the imaging unit 130 may obtain the difference between the height of the outer periphery of the back surface 102 of the wafer 100 and the height of the holding surface 22 of the chuck table 20, which has been acquired in advance, as a value corresponding to the amount of warpage of the wafer 100, and the groove condition determination unit 8 may determine, based on this difference, the number of grooves to be formed on the back surface 102 of the wafer 100, etc. In this configuration, it is possible to omit measuring the height of the center of the back surface 102 of the wafer 100.

[0106] In this embodiment, in the warpage amount measuring step, the first camera 131 of the imaging unit 130 measures the height of the outer periphery and the height of the center of the back surface 102 of the wafer 100 placed on the temporary placement table 154 of the temporary placement mechanism 152. 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 can focus on the outer periphery and the center of the back surface 102 of the wafer 100 held on the temporary placement table 154 via the dichroic mirror 184 and the condenser 182. [Explanation of symbols]

[0107] 1: grinding device, 7: control unit, 8: groove condition determination 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 surface, 39: Cover plate, 60: Grinding feed 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 stone, 80: Thickness measuring instrument, 81: Holding surface height gauge, 82: Upper surface height gauge, 100: Wafer, 101: front surface, 102: back surface, 110: processing unit, 111: gate-type column, 112: Housing, 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 part, 138: Second opening part, 139: Tip portion, 140: Y-axis direction moving 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: holding stand, 150: holding 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: loading mechanism; 171: suction pad, 172: discharge mechanism, 173: suction pad, 180: laser oscillator, 182: condenser, 184: dichroic mirror, 186: Elevating mechanism, 187: Second camera, 191: fluid injection nozzle, 192: fluid source, 193: fluid recovery nozzle, 194: suction source, 201: oscillator, 205: X-axis galvanometer mirror section, 206: X-axis mirror, 207: X-axis actuator, 210: Y-axis galvanometer mirror section, 211: Y-axis mirror, 212: Y-axis actuator, 215: direction-changing mirror, 217: fθ lens, 300: laser beam, 301: laser beam, 310: processing point, 401: groove

Claims

[Claim 1] A grinding device comprising: a chuck table that uses a holding surface to suction-hold a bottom surface of a workpiece having an outer periphery that is warped upward; and a grinding mechanism that uses a grinding wheel to grind an upper surface of the workpiece held by the holding surface, a groove forming unit that forms a groove in the upper surface of the workpiece to a depth equal to or less than the depth to be ground by the grinding wheel before the workpiece is held by the holding surface; The groove forming unit comprises: a support unit that supports the workpiece; a laser processing unit that irradiates an upper surface of the workpiece supported by the support unit with a laser beam having a wavelength that is absorbed by the workpiece; a height measuring device for measuring the height of the warped outer periphery of the workpiece supported by the support unit and the height of the central upper surface of the workpiece supported by the support unit; a warpage amount calculation unit that calculates the difference between the height of the outer periphery and the height of the central upper surface measured by the height measuring device, a groove condition determination unit that determines at least the number of grooves based on the difference calculated by the warpage amount calculation unit, the laser processing unit positions a focal point of a laser beam in accordance with the height of the upper surface of the workpiece supported by the support unit, and forms the groove on the upper surface of the workpiece by the laser beam, thereby weakening the force of the workpiece warping up; Grinding equipment.

Images