Grinding device and work-piece grinding method

Abstract

To reduce an air cut amount when grinding a work-piece.SOLUTION: A height position of a rough grinding unit 30 when an undersurface of a rough grinding wheel 306 is detected and a height of a top face of a wafer 100 are detected, and on the basis of the detection result, an origin position, which is the height position of the rough grinding unit 30 when the undersurface of the rough grinding wheel 306 contacts the top face of the wafer 100, is calculated. Therefore, the origin position of the rough grinding unit 30 can be correctly determined. Accordingly, when the rough grinding unit 30 is lowered to a griding start position, which is higher than the origin position by only a prescribed distance, at a hight speed, the prescribed distance can be extremely shortened, that is, the grinding start position can be set directly above the top face of the wafer 100. Therefore, during high-speed lowering, the air cut amount when grinding the wafer 100 while lowering the rough grinding unit 30 at a low speed can be extremely reduced.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a grinding apparatus and a method for grinding a workpiece. [Background technology]

[0002] When a rotating grinding wheel is lowered toward the wafer to grind it, the grinding wheel's descent speed is fast until it reaches the upper surface of the wafer, and then slows down to bring the grinding wheel into contact with the wafer. This process of lowering the grinding wheel at a slow speed from the upper surface of the wafer until it comes into contact with the wafer is called air cutting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-97089 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, because the exact distance between the tip of the grinding wheel and the top surface of the wafer is unknown, the amount of air cut is set large to prevent the grinding wheel and the wafer from coming into contact at high speed, but setting the amount of air cut large reduces productivity.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to reduce the amount of air cut when grinding a workpiece such as a wafer. [Means for solving the problem]

[0006] The grinding apparatus of the present invention (the present grinding apparatus) is a grinding apparatus for grinding a workpiece, and includes at least a chuck table having a holding surface for holding the workpiece, a grinding unit having a spindle on which a grinding wheel having grinding stones arranged in a ring shape is mounted, a grinding feed mechanism for moving the grinding unit in a direction perpendicular to the holding surface, a bottom surface detection unit for detecting the bottom surface of the grinding stone when the grinding unit is lowered by the grinding feed mechanism, a top surface detection unit for detecting the height of the top surface of the workpiece held on the chuck table, and a control unit, and the control The unit is equipped with an origin position calculation section that calculates the origin position, which is the height position of the grinding unit when the lower surface of the grinding wheel contacts the upper surface of the workpiece, based on the height position of the grinding unit when the lower surface of the grinding wheel is detected by the lower surface detection unit and the height of the upper surface of the workpiece detected using the upper surface detection section, and the control unit lowers the grinding unit at high speed until it reaches a grinding start position that is a predetermined distance higher than the origin position of the grinding unit calculated by the origin position calculation section, and then grinds the workpiece while lowering the grinding unit at a low speed.

[0007] The grinding apparatus may further include a turntable having a plurality of the chuck tables, and the control unit may be configured to rotate the turntable to position the chuck table holding the workpiece below the grinding wheel, and while the turntable is rotating, the underside detection unit may detect the underside of the grinding wheel when the grinding unit is lowered by the grinding feed mechanism.

[0008] The grinding method for a workpiece of the present invention (the present grinding method) is a method for grinding a workpiece held on a chuck table by a grinding wheel of a grinding unit, and includes a holding step for holding the workpiece by the chuck table, a bottom surface detection step for detecting the bottom surface of the grinding wheel when the grinding unit is lowered, an top surface detection step for detecting the height of the top surface of the workpiece held on the chuck table, and a height position of the grinding unit when the bottom surface of the grinding wheel is detected in the bottom surface detection step. The method includes an origin position calculation step for calculating an origin position, which is the height position of the grinding unit when the lower surface of the grinding wheel contacts the upper surface of the workpiece, based on the height of the upper surface of the workpiece detected in the upper surface detection step; a high-speed lowering step for lowering the grinding unit at high speed until it reaches a grinding start position that is a predetermined distance higher than the origin position of the grinding unit calculated in the origin position calculation step; and a grinding step for grinding the workpiece while lowering the grinding unit at a low speed after the high-speed lowering step.

[0009] A plurality of the chuck tables may be disposed on a turntable. In this case, the grinding method may further include a turntable rotating step of rotating the turntable to position the chuck table holding the workpiece in the holding step below the grinding wheel, and the lower surface detecting step may be performed simultaneously with the turntable rotating step. [Effects of the Invention]

[0010] In this invention, the height position of the grinding unit when the bottom surface of the grinding wheel is detected and the height of the top surface of the workpiece are detected, and based on the detection results, the origin position, which is the height position of the grinding unit when the bottom surface of the grinding wheel comes into contact with the top surface of the workpiece, is calculated. This makes it possible to accurately determine the origin position of the grinding unit.

[0011] Therefore, when the grinding unit is lowered at high speed to a grinding start position that is a predetermined distance higher than the origin position, this predetermined distance can be made extremely short, i.e., the grinding start position can be set directly above the upper surface of the workpiece. As a result, the amount of air cutting when grinding the workpiece while lowering the grinding unit at a low speed after the high-speed descent can be significantly reduced. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a perspective view showing the configuration of a grinding device. [Figure 2] FIG. 2(a) is a perspective view showing the configuration of the lower surface detection unit, and FIG. 2(b) is a side view of the same. [Figure 3] 10A and 10B are cross-sectional views showing a lower surface detection step and an upper surface detection step. [Figure 4] FIG. 10 is a cross-sectional view showing a high-speed descending step. [Figure 5] FIG. [Figure 6] 10A and 10B are cross-sectional views showing another upper surface detection step. DETAILED DESCRIPTION OF THE INVENTION

[0013] The grinding apparatus 1 shown in FIG. 1 grinds a wafer 100 held on a chuck table 5 by a rough grinding unit 30 and a finish grinding unit 31 .

[0014] 1 is an example of a workpiece, such as a circular semiconductor wafer. A device (not shown) is formed on a front surface 101 of the wafer 100. A back surface 103 of the wafer 100 is the surface to be ground.

[0015] The grinding apparatus 1 has a first apparatus base 10 and a second apparatus base 11 disposed behind (on the +Y direction side of) the first apparatus base 10. The first apparatus base 10 has a loading / unloading area 401 where the wafer 100 is loaded and unloaded. The second apparatus base 11 has a processing area 402. In this processing area 402, the wafer 100 held on the chuck table 5 is processed by the rough grinding unit 30 and the finish grinding unit 31.

[0016] A first cassette stage 160 and a second cassette stage 162 for placing cassettes are provided on the front side (-Y direction side) of the first equipment base 10. A first cassette 161 and a second cassette 163 for accommodating wafers 100 are placed on the first cassette stage 160 and the second cassette stage 162, respectively.

[0017] 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.

[0018] The openings (not shown) of the first cassette 161 and the second cassette 163 face the +Y direction. A robot 155 is disposed on the +Y direction side of these openings. The robot 155 has a holding surface for holding the wafer 100. The robot 155 carries the processed wafer 100 into the first cassette 161 or the second cassette 163. The robot 155 also removes the unprocessed wafer 100 stored in the first cassette 161 or the second cassette 163 and places it on the temporary placement table 154 of the temporary placement mechanism 152.

[0019] The temporary placement mechanism 152 is used to temporarily place the wafers 100 taken out from the first cassette 161 or the second cassette 163, and is provided at a position adjacent to the robot 155. The temporary placement mechanism 152 has a temporary placement table 154 and an alignment member 153. The alignment member 153 has 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 the circle connecting the multiple alignment pins. As a result, the wafer 100 placed on the temporary placement table 154 with the back surface 103 facing up is aligned (centered) at a predetermined position.

[0020] A carry-in mechanism 170 is provided at a position adjacent to the temporary placement mechanism 152. The carry-in mechanism 170 carries the wafer 100, which is temporarily placed on the temporary placement mechanism 152, into the chuck table 5. The carry-in mechanism 170 is provided with a transfer pad 171 that suction-holds the back surface 103 of the wafer 100. The carry-in mechanism 170 suction-holds the wafer 100, which is temporarily placed on the temporary placement table 154, with the transfer pad 171, transports the wafer 100 to the chuck table 5 located near the temporary placement mechanism 152 in the processing area 402, and places the wafer on its holding surface 50.

[0021] The chuck table 5 is a member that rotates while holding the wafer 100, and has a holding surface 50 that holds the wafer 100. The holding surface 50 is connected to a suction source (not shown) and is capable of suction-holding the wafer 100. The chuck table 5 holds the wafer 100 by means of the holding surface 50 and is rotatable about a central axis that passes through the center of the holding surface 50 and extends in the Z-axis direction.

[0022] In this embodiment, a plurality of chuck tables 5 are disposed on the upper surface of a turntable 6 disposed on the second apparatus base 11. In this embodiment, three chuck tables 5 are disposed at equal intervals on a circle centered on the center of the turntable 6. A rotating shaft (not shown) for rotating the turntable 6 is disposed at the center of the turntable 6. This rotating shaft allows the turntable 6 to rotate about an axis extending in the Z-axis direction. The rotation of the turntable 6 causes the three chuck tables 5 to revolve. This allows the chuck tables 5 to be positioned sequentially near the temporary placement mechanism 152, below the rough grinding unit 30, and below the finish grinding unit 31.

[0023] A first column 12 is erected at the rear (+Y direction side) of the second apparatus base 11. A rough grinding unit 30 that rough grinds the wafer 100 and a rough grinding feed mechanism 20 that grinds and feeds the rough grinding unit 30 are disposed in front of the first column 12. The rough grinding unit 30 is an example of a grinding unit having a spindle on which a grinding wheel having grinding stones arranged in a ring is attached, and rough grinds the wafer 100.

[0024] The rough grinding feed mechanism 20 is a vertical movement mechanism that moves the rough grinding unit 30 in a direction perpendicular to the holding surface 50. The rough grinding feed mechanism 20 includes a pair of guide rails 201 parallel to the Z-axis direction, a lift table 203 that slides on the guide rails 201, a ball screw 200 parallel to the guide rails 201, a motor 202 that rotates the ball screw 200, an encoder 205 that detects the rotation angle of the motor 202, and a holder 204 attached to the front (surface) of the lift table 203. The holder 204 holds the rough grinding unit 30.

[0025] The lift table 203 is slidably installed on the guide rail 201. A nut portion (not shown) is fixed to the lift table 203. A ball screw 200 is threadedly engaged with this nut portion. The motor 202 is connected to one end of the ball screw 200.

[0026] In the rough grinding feed mechanism 20, the motor 202 rotates the ball screw 200, causing the lifting table 203 to move in the Z-axis direction along the guide rail 201. As a result, the holder 204 attached to the lifting table 203 and the rough grinding unit 30 held by the holder 204 also move in the Z-axis direction together with the lifting table 203. In this way, the rough grinding feed mechanism 20 grinds and feeds the rough grinding unit 30 along the Z-axis direction.

[0027] Furthermore, the encoder 205 can recognize the height of the rough grinding unit 30 (for example, the height of the upper surface of a wheel mount 303, which will be described later) moved by the rough grinding feed mechanism 20 by detecting the rotation angle of the motor 202. Note that the height of this rough grinding unit 30 is a height based on an arbitrary position of the grinding apparatus 1. For example, in this embodiment, the height of the rough grinding unit 30 is a height based on the upper surface of the turntable 6.

[0028] The rough grinding unit 30 includes a spindle housing 301 fixed to the holder 204, a spindle 300 rotatably held in the spindle housing 301, a spindle motor 302 that rotates and drives the spindle 300, a wheel mount 303 attached to the lower end of the spindle 300, and a grinding wheel 304 detachably attached to the lower surface of the wheel mount 303.

[0029] The spindle housing 301 is held by the holder 204 so as to extend in the Z-axis direction. The spindle 300 extends in the Z-axis direction so as to be perpendicular to the holding surface 50 of the chuck table 5, and is rotatably supported by the spindle housing 301.

[0030] Spindle motor 302 is connected to the upper end side of spindle 300. Spindle motor 302 causes spindle 300 to rotate as indicated by arrow 501 around a rotation axis extending in the Z-axis direction.

[0031] The wheel mount 303 is formed in a disk shape, is fixed to the tip (lower end) of the spindle 300, and rotates in accordance with the rotation of the spindle 300. The wheel mount 303 supports the grinding wheel 304.

[0032] The grinding wheel 304 is formed to have an outer diameter that is approximately the same as the outer diameter of the wheel mount 303. The grinding wheel 304 includes an annular wheel base 305 made of a metal material. A plurality of roughly rectangular parallelepiped rough grinding stones 306 are annularly arranged and fixed around the entire circumference of the underside of the wheel base 305.

[0033] The rough grinding wheel 306 is rotated by the rotation of the spindle 300, and its lower surface roughly grinds the back surface 103 of the wafer 100 held on the chuck table 5. The rough grinding wheel 306 is an example of a processing tool attached to the tip of the spindle 300, and is a grinding wheel containing relatively large abrasive grains.

[0034] Furthermore, a second column 13 is erected at the rear of the second apparatus base 11 so as to be adjacent to the first column 12 along the X-axis direction. A finish grinding unit 31 that finish-grinds the wafers 100 and a finish grinding feed mechanism 21 that feeds the finish grinding unit 31 are disposed in front of the second column 13. The finish grinding unit 31 is an example of a grinding unit having a spindle on which a grinding wheel having grinding stones arranged in a ring is mounted, and finish-grinds the wafers 100.

[0035] Similar to the rough grinding feed mechanism 20, the finish grinding feed mechanism 21 is a vertical movement mechanism that moves the finish grinding unit 31 in a direction perpendicular to the holding surface 50. The finish grinding feed mechanism 21 has a configuration similar to that of the rough grinding feed mechanism 20, and can feed the finish grinding unit 31 for grinding along the Z-axis direction.

[0036] The finish grinding unit 31 has the same configuration as the rough grinding unit 30, except that it is equipped with a finish grinding wheel 307 instead of the rough grinding wheel 306. The finish grinding wheel 307 is rotated by the rotation of the spindle 300, and its lower surface finish-grinds the back surface 103 of the wafer 100 held on the chuck table 5. The finish grinding wheel 307 is an example of a processing tool attached to the tip of the spindle 300, and is a grinding wheel containing relatively small abrasive grains.

[0037] The wafer 100 after finish grinding is carried out by a carry-out mechanism 172. The carry-out mechanism 172 is provided with a transfer pad 173 that suction-holds the back surface 103 of the wafer 100. The carry-out mechanism 172 suction-holds the back surface 103 of the wafer 100 after finish grinding, which is placed on the chuck table 5, by the transfer pad 173. Thereafter, the carry-out mechanism 172 carries the wafer 100 out of the chuck table 5 and carries it 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. 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 by the robot 155 into the first cassette 161 or the second cassette 163 (for example, the cassette from which the wafer 100 was removed).

[0041] A fixed pillar 8 is provided in the center of the turntable 6 of the grinding apparatus 1. This fixed pillar 8 does not rotate with the rotation of the turntable 6, but is fixed and stands upright. A first measuring mechanism 41 and a second measuring mechanism 45 are disposed on this fixed pillar 8.

[0042] The first measuring mechanism 41 measures the height of the holding surface 50 of the chuck table 5 arranged below the rough grinding unit 30 and the height of the wafer 100 held on this holding surface 50. On the other hand, the second measuring mechanism 45 measures the height of the holding surface 50 of the chuck table 5 arranged below the finish grinding unit 31 and the height of the wafer 100 held on this holding surface 50.

[0043] The first measuring mechanism 41 and the second measuring mechanism 45 have a holding surface height measuring instrument 42 that can come into contact with the frame surface 51 of the chuck table 5, which is flush with the holding surface 50, and measure the height of the frame surface 51, and a wafer height measuring instrument 43 that can come into contact with the back surface 103, which is the upper surface of the wafer 100 held on the holding surface 50, and measure the height of the back surface 103. The wafer height measuring instrument 43 is an example of an upper surface detecting unit that detects the height of the back surface 103, which is the upper surface of the wafer 100 held on the chuck table 5.

[0044] Using these holding surface height measuring device 42 and wafer height measuring device 43, the first measuring mechanism 41 and the second measuring mechanism 45 can measure the height of the holding surface 50 of the chuck table 5, which is flush with the frame surface 51, and the height of the wafer 100 held on the holding surface 50 (height of the back surface 103). Furthermore, the first measuring mechanism 41 and the second measuring mechanism 45 can also calculate the thickness of the wafer 100 based on the difference between the measured height of the holding surface 50 and the height of the wafer 100 .

[0045] In this embodiment, the height of the holding surface 50 obtained by the holding surface height measuring device 42 and the height of the back surface 103 of the wafer 100 obtained by the wafer height measuring device 43 are heights based on the top surface of the turntable 6, similar to the height of the rough grinding unit 30.

[0046] Further, a first lower surface detection unit 81 and a second lower surface detection unit 82 are provided near the first column 12 and the second column 13, respectively.

[0047] The first lower surface detection unit 81 is disposed near the rough grinding unit 30. The first lower surface detection unit 81 detects the lower surface of the rough grinding wheel 306 when the rough grinding unit 30 is lowered by the rough grinding feed mechanism 20.

[0048] On the other hand, the second lower surface detection unit 82 is disposed near the finish grinding unit 31. The second lower surface detection unit 82 detects the lower surface of the finish grinding wheel 307 when the finish grinding unit 31 is lowered by the finish grinding feed mechanism 21. The configurations of the first lower surface detection unit 81 and the second lower surface detection unit 82 will be described later.

[0049] The grinding device 1 also includes a housing 15 that covers the first device base 10 and the second device base 11. A touch panel 60 is provided on the side of the housing 15.

[0050] The touch panel 60 displays various information such as processing conditions related to the grinding device 1. The touch panel 60 is also used to set various information. In this way, the touch panel 60 functions as an input member for inputting information and also as a display member for displaying information.

[0051] The grinding apparatus 1 also has therein 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 controls the above-mentioned components of the grinding apparatus 1 to grind the wafer 100. The control unit 7 also includes an origin position calculation unit 71, as shown in FIG. 1.

[0052] The following describes a method for grinding the wafer 100 in the grinding apparatus 1 controlled by the control unit 7 and the origin position calculation unit 71. This grinding method is a method for grinding the wafer 100 held on the chuck table 5 with the rough grinding wheel 306 of the rough grinding unit 30 and the finish grinding wheel 307 of the finish grinding unit 31.

[0053] [1] Holding step First, a holding step is performed. In this step, the wafer 100 is held by the chuck table 5. Specifically, the control unit 7 controls the robot 155 shown in FIG. 1 to take out the unprocessed wafer 100 from the first cassette 161 or the second cassette 163, place it on the temporary placement table 154 of the temporary placement mechanism 152, and align the wafer 100. Furthermore, the control unit 7 controls the carry-in mechanism 170 to hold the wafer 100 on the temporary placement table 154, and place the wafer 100 with its back surface 103 facing up on the holding surface 50 of the chuck table 5 arranged near the temporary placement mechanism 152.

[0054] Thereafter, the control unit 7 connects the holding surface 50 to a suction source (not shown), whereby the holding surface 50 holds the wafer 100 by suction. In this manner, the chuck table 5 holds the wafer 100 by means of the holding surface 50.

[0055] [2] Rough grinding process After the holding step, a rough grinding step is performed in which the wafer 100 held on the chuck table 5 is roughly ground by the rough grinding unit 30. The rough grinding process includes a turntable rotation step, a bottom surface detection step, a top surface detection step, an origin position calculation step, a high-speed lowering step, and a grinding step. Each step will be described below.

[0056] (2-1) Turntable rotation step In the rough grinding process, first, a turntable rotation step is performed. In this step, the control unit 7 rotates the turntable 6 to position the chuck table 5, which has held the wafer 100 in the holding step, below the rough grinding wheel 306 of the rough grinding unit 30.

[0057] (2-2) Bottom detection step Additionally, a bottom surface detection step is performed overlapping with the turntable rotation step. In this bottom surface detection step, the bottom surface of the rough grinding wheel 306 is detected when the rough grinding unit 30 is lowered. In this step, the first bottom surface detection unit 81 is used. That is, in this step, while the turntable 6 is rotating, the first bottom surface detection unit 81 detects the bottom surface of the rough grinding wheel 306 when the rough grinding unit 30 is lowered by the rough grinding feed mechanism 20.

[0058] 2(a), the first lower surface detection unit 81 is, for example, an NCS (non-contact setup) sensor, and has a detector 90, an arm 86 that extends horizontally and supports the detector 90 at its tip, a support member 87 that extends in the Z-axis direction and supports the arm 86, and a motor 88. The motor 88 rotates the support member 87, thereby turning the arm 86 and the detector 90.

[0059] 2(a) and 2(b), the detector 90 has a U-shaped groove 91. This groove 91 is configured to sandwich a rough grinding wheel 306 and a finish grinding wheel 307. A light-projecting unit 92 that emits measurement light and a light-receiving unit 93 that receives the measurement light are provided on two inner surfaces of this groove 91, facing each other. The heights of the light-projecting unit 92 and the light-receiving unit 93 (heights relative to the top surface of the turntable 6) are recognized in advance by the control unit 7 and the origin position calculation unit 71. The second lower surface detection unit 82 has the same configuration as the first lower surface detection unit 81.

[0060] 3, in the underside detection step using the first underside detection unit 81, the control unit 7 rotates the arm part 86 using the motor 88 of the first underside detection unit 81, thereby positioning the detector 90 below the rough grinding wheel 306, for example, below the part of the rough grinding wheel 306 that protrudes from the holding surface 50. Furthermore, the control unit 7 controls the light-emitting part 92 of the detector 90 to irradiate the light-receiving part 93 with measurement light.

[0061] Furthermore, the control unit 7 causes the rough grinding unit 30 to descend using the rough grinding feed mechanism 20. As the rough grinding unit 30 descends, the rough grinding wheel 306 is sandwiched in the groove 91 of the detector 90, and as shown in FIGS. 2(b) and 3, when the lower surface of the rough grinding wheel 306 is positioned between the light-projecting unit 92 and the light-receiving unit 93, the amount of light received by the light-receiving unit 93, which receives the measurement light from the light-projecting unit 92, decreases. In response to this decrease in the amount of light received by the light-receiving unit 93, the detector 90 turns ON. The detector 90 may be configured to be turned on when the light receiving section 93 no longer receives the measurement light.

[0062] When the detector 90 is turned ON, the control unit 7 determines that the lower surface of the rough grinding wheel 306 has reached the height position of the light-emitting section 92 and the light-receiving section 93 of the detector 90, stops the descent of the rough grinding unit 30, and acquires the height of the rough grinding unit 30 at this time (T3 shown in Figure 3) using the encoder 205 of the rough grinding feed mechanism 20.

[0063] (2-3) Upper surface detection step After the turntable rotating step and the bottom surface detecting step, an top surface detecting step is performed. In this step, the height of the top surface (back surface 103) of the wafer 100 held on the chuck table 5 is detected (acquired). Specifically, the control unit 7 brings the wafer height measuring device 43 of the first measuring mechanism 41 into contact with the back surface 103 of the wafer 100 placed below the rough grinding wheel 306, and detects the height of the back surface 103 (T2 shown in FIG. 3).

[0064] (2-4) Origin position calculation step After the upper surface detection step, an origin position calculation step is performed. In this step, the origin position calculation section 71 of the control unit 7 calculates the origin position, which is the height position of the rough grinding unit 30 when the lower surface of the rough grinding wheel 306 comes into contact with the upper surface of the wafer 100, based on the height position (T3) of the rough grinding unit 30 when the lower surface of the rough grinding wheel 306 is detected by the first lower surface detection unit 81 in the lower surface detection step and the height (T2) of the upper surface of the wafer 100 detected by the wafer height measuring device 43 in the upper surface detection step.

[0065] 3, the origin position calculation unit 71 determines the difference (T4 shown in FIG. 3) between the height (T1) of the light-projecting unit 92 and the light-receiving unit 93, which has been recognized in advance, and the height (T2) of the upper surface of the wafer 100. Then, the origin position calculation unit 71 subtracts this difference (T4) from the height (T3) of the rough grinding unit 30 detected in the lower surface detection step, thereby determining the origin position of the rough grinding unit 30, which is the height position of the rough grinding unit 30 when the lower surface of the rough grinding wheel 306 comes into contact with the upper surface of the wafer 100.

[0066] (2-5) High-speed descending step After the origin position calculation step, a high-speed lowering step is performed in which the control unit 7 lowers the rough grinding unit 30 at high speed until the rough grinding unit 30 reaches a grinding start position that is a predetermined distance higher than the origin position of the rough grinding unit 30 calculated by the origin position calculation section 71 in the origin position calculation step. 4, the control unit 7 first rotates the spindle 300 using the spindle motor 302 of the rough grinding unit 30 (arrow 502). This rotates the rough grinding wheel 306 attached to the lower end of the spindle 300. Furthermore, the control unit 7 rotates the chuck table 5 holding the wafer 100 using a table rotation mechanism (not shown) (arrow 503).

[0067] Next, the control unit 7 calculates the rough grinding start position of the rough grinding unit 30, which is a position a predetermined distance higher than the origin position of the rough grinding unit 30 calculated in the origin position calculation step. This rough grinding start position is, for example, a height position where the lower surface of the rough grinding wheel 306 is located directly above the wafer 100 held on the chuck table 5, as shown in FIG.

[0068] 4, the control unit 7 uses the rough grinding feed mechanism 20 to lower the rough grinding unit 30 and position the rough grinding unit 30 at the rough grinding start position. At this time, the control unit 7 uses the rough grinding feed mechanism 20 to lower the rough grinding unit 30 at a relatively high initial speed and position the rough grinding unit 30 at the rough grinding start position.

[0069] (2-6) Grinding step After the high-speed lowering step, a grinding step is performed, in which the control unit 7 grinds the wafer 100 while lowering the rough grinding unit 30 at a low speed. 5, the control unit 7 uses the rough grinding feed mechanism 20 to lower the rough grinding unit 30, which is located at the rough grinding start position, at a relatively slow rough grinding speed (arrow 505), thereby performing rough grinding of the wafer 100. At this time, the control unit 7 uses the first measuring mechanism 41 (see FIG. 1) to measure the thickness of the wafer 100 being ground, and performs rough grinding until this thickness reaches a predetermined rough grinding thickness.

[0070] [3] Finish grinding process After the rough grinding step, a finish grinding step is performed in which the wafer 100 held on the chuck table 5 is finish-ground by the finish grinding unit 31.

[0071] The finish grinding process also includes the same steps as the rough grinding process: a turntable rotation step, a bottom surface detection step, a top surface detection step, an origin position calculation step, a high-speed lowering step, and a grinding step.

[0072] (3-1) Turntable rotation step In the turntable rotation step of the finish grinding process, the control unit 7 rotates the turntable 6 to position the chuck table 5 holding the roughly ground wafer 100 below the finish grinding wheel 307 of the finish grinding unit 31.

[0073] (3-2) Bottom detection step Additionally, a bottom surface detection step is performed overlapping with the turntable rotation step. In this bottom surface detection step, the bottom surface of the finish grinding wheel 307 is detected when the finish grinding unit 31 is lowered. In this step, the second bottom surface detection unit 82 is used. That is, in this step, while the turntable 6 is rotating, the second bottom surface detection unit 82 detects the bottom surface of the finish grinding wheel 307 when the finish grinding unit 31 is lowered by the finish grinding feed mechanism 21.

[0074] In the underside detection step using the second underside detection unit 82, as shown in Fig. 3, the control unit 7 rotates the arm part 86 by the motor 88 of the second underside detection unit 82, thereby positioning the detector 90 below the finish grinding wheel 307. Furthermore, the control unit 7 irradiates measurement light from the light-emitting part 92 of the detector 90 toward the light-receiving part 93.

[0075] Furthermore, the control unit 7 lowers the finish grinding unit 31 using the finish grinding feed mechanism 21. Then, as the finish grinding unit 31 lowers, the lower surface of the finish grinding wheel 307 is positioned between the light-emitting unit 92 and the light-receiving unit 93, and the amount of light received by the light-receiving unit 93 decreases, causing the detector 90 to turn ON.

[0076] When the detector 90 turns ON, the control unit 7 determines that the underside of the finish grinding wheel 307 has reached the height position of the light-emitting section 92 and the light-receiving section 93 of the detector 90, stops the descent of the finish grinding unit 31, and obtains the height (T3) of the finish grinding unit 31 at this time using the encoder 205 of the finish grinding feed mechanism 21.

[0077] (3-3) Upper surface detection step After the turntable rotation step and the bottom surface detection step, an top surface detection step is performed. In this step, the height of the top surface (back surface 103) of the wafer 100 held on the chuck table 5 is detected (acquired). Specifically, the control unit 7 brings the wafer height measuring device 43 of the second measurement mechanism 45 into contact with the back surface 103 of the wafer 100 placed below the finish grinding wheel 307, and detects the height (T2) of the back surface 103.

[0078] (3-4) Origin position calculation step After the upper surface detection step, an origin position calculation step is performed. In this step, the origin position calculation section 71 of the control unit 7 calculates the origin position, which is the height position of the finish grinding unit 31 when the lower surface of the finish grinding wheel 307 comes into contact with the upper surface of the wafer 100, based on the height position (T3) of the finish grinding unit 31 when the lower surface of the finish grinding wheel 307 is detected by the second lower surface detection unit 82 in the lower surface detection step and the height (T2) of the upper surface of the wafer 100 detected by the wafer height measuring device 43 in the upper surface detection step.

[0079] For example, the origin position calculation unit 71 determines the difference (T4) between the height (T1) of the light-projecting unit 92 and the light-receiving unit 93 and the height (T2) of the upper surface of the wafer 100. Then, the origin position calculation unit 71 determines the origin position of the finish grinding unit 31 by subtracting this difference (T4) from the height (T3) of the finish grinding unit 31 detected in the lower surface detection step.

[0080] (3-5) High-speed descending step After the origin position calculation step, a high-speed lowering step is performed in which the control unit 7 lowers the finish grinding unit 31 at high speed until the finish grinding unit 31 reaches a grinding start position that is a predetermined distance higher than the origin position of the finish grinding unit 31 calculated by the origin position calculation section 71 in the origin position calculation step.

[0081] Specifically, the control unit 7 first rotates the finish grinding wheel 307 of the finish grinding unit 31 and also rotates the chuck table 5 holding the wafer 100, as shown in FIG. Next, the control unit 7 calculates the finish grinding start position of the finish grinding unit 31, which is a position a predetermined distance higher than the origin position of the finish grinding unit 31 calculated in the origin position calculation step. This finish grinding start position is, for example, a height position where the lower surface of the finish grinding wheel 307 is located directly above the wafer 100 held on the chuck table 5, as shown in FIG.

[0082] 4, the control unit 7 uses the finish grinding feed mechanism 21 to lower the finish grinding unit 31 and position the finish grinding unit 31 at the finish grinding start position. At this time, the control unit 7 uses the finish grinding feed mechanism 21 to lower the finish grinding unit 31 at a relatively high initial speed and position the finish grinding unit 31 at the finish grinding start position.

[0083] (3-6) Grinding step After the high-speed lowering step, the grinding step is performed, in which the control unit 7 grinds the wafer 100 while lowering the finish grinding unit 31 at a low speed. Specifically, as shown in Fig. 5, the control unit 7 uses the finish grinding feed mechanism 21 to lower the finish grinding unit 31, which is located at the finish grinding start position, at a relatively slow finish grinding speed to perform finish grinding on the wafer 100. At this time, the control unit 7 uses the second measuring mechanism 45 (see Fig. 1) to measure the thickness of the wafer 100 being ground, and performs finish grinding until this thickness reaches a predetermined finish grinding thickness.

[0084] As described above, in this embodiment, in the origin position calculation step, the height position of the rough grinding unit 30 (finish grinding unit 31) when the lower surface of the rough grinding wheel 306 (finish grinding wheel 307) is detected and the height of the upper surface of the wafer 100 are detected, and based on the detection results, the origin position is calculated, which is the height position of the rough grinding unit 30 (finish grinding unit 31) when the lower surface of the rough grinding wheel 306 (finish grinding wheel 307) comes into contact with the upper surface of the wafer 100. Therefore, it is possible to accurately determine the origin position of the rough grinding unit 30 (finish grinding unit 31).

[0085] Therefore, when the rough grinding unit 30 (finish grinding unit 31) is lowered at high speed to a grinding start position that is a predetermined distance higher than the origin position, this predetermined distance can be made extremely short, that is, the grinding start position can be set directly above the upper surface of the wafer 100. Therefore, after the high-speed descent, the amount of air cutting when grinding the wafer 100 while lowering the rough grinding unit 30 (finish grinding unit 31) at a low speed can be significantly reduced.

[0086] In this embodiment, the bottom surface detection step is performed in conjunction with the turntable rotation step. That is, while the turntable 6 is rotating, the first bottom surface detection unit 81 (second bottom surface detection unit 82) detects the bottom surface of the rough grinding wheel 306 (finish grinding wheel 307) when the rough grinding unit 30 (finish grinding unit 31) is lowered by the rough grinding feed mechanism 20 (finish grinding feed mechanism 21). Therefore, the turntable rotation step and the bottom surface detection step can be performed simultaneously, which makes it possible to increase productivity.

[0087] Furthermore, in this embodiment, in the lower surface detection step, the control unit 7 acquires the height (T3) of the rough grinding unit 30 (finish grinding unit 31) when the lower surface of the rough grinding wheel 306 (finish grinding wheel 307) reaches the height position of the light projecting unit 92 and the light receiving unit 93 of the detector 90 of the first lower surface detection unit 81 (second lower surface detection unit 82). Therefore, the control unit 7 can accurately confirm the amount of wear of the rough grinding wheel 306 (finish grinding wheel 307) based on this height (T3).

[0088] It is preferable that the bottom surface detection step is started after the turntable 6 starts to rotate and is completed before the turntable 6 finishes rotating. This can eliminate the time required just for the bottom surface detection step. However, it is sufficient if the turntable rotation step and the bottom surface detection step partially overlap. Even in this case, the effect of improving productivity can be obtained.

[0089] In this embodiment, the grinding apparatus 1 is provided with a turntable 6 having a plurality of chuck tables 5. In this regard, the grinding apparatus 1 may be configured to have one chuck table 5 without including the turntable 6.

[0090] In addition, in this embodiment, the grinding apparatus 1 is equipped with a wafer height measuring device 43 as an upper surface detection unit for detecting the height of the back surface 103, which is the upper surface of the wafer 100 held on the chuck table 5.

[0091] In this regard, the upper surface detection unit of the grinding apparatus 1 may be a block gauge 95 as shown in Fig. 6. The block gauge 95 has a contact surface 96 for contacting the rough grinding wheel 306 (finish grinding wheel 307). The distance between the lower surface of the block gauge 95 and the contact surface 96 (the thickness of the block gauge 95) is, for example, 5 mm.

[0092] In this case, for example, in the upper surface detection step of the rough grinding process, an operator or a transfer device (not shown) places the block gauge 95 on the holding surface 50 of the chuck table 5. Thereafter, the control unit 7 causes the rough grinding unit 30 to descend using the rough grinding feed mechanism 20, so that the lower surface of the rough grinding wheel 306 comes into contact with the contact surface 96 of the block gauge 95. Then, the control unit 7 uses the encoder 205 to obtain the height position of the rough grinding unit 30 when the lower surface of the rough grinding wheel 306 comes into contact with the contact surface 96.

[0093] Next, the control unit 7 calculates the height of the holding surface 50 by subtracting the thickness of the block gauge 95 from the height position of the rough grinding unit 30. Furthermore, the control unit 7 adds the specified thickness (e.g., 300 μm) of the wafer 100 before grinding to the height of the holding surface 50, thereby calculating the height of the upper surface of the wafer 100 held on the holding surface 50 of the chuck table 5. With this configuration, it is not necessary to perform the upper surface detection step for each wafer 100, thereby improving productivity.

[0094] The holding surface 50 of the chuck table 5 is self-ground by the rough grinding wheel 306 at a predetermined timing, and its height is lowered. Therefore, after the self-grinding, the top surface detection step using the block gauge 95 is performed again, or the top surface detection step using the wafer height measuring device 43 is performed.

[0095] Furthermore, by using such a block gauge 95, it is possible to ensure consistency between the height of the rough grinding unit 30 obtained by the encoder 205 and the height of the wafer 100 measured by the wafer height measuring device 43.

[0096] In other words, the height of the top surface of the wafer 100 relative to the rough grinding unit 30 can be determined by subtracting the thickness of the block gauge 95 from the height position of the rough grinding unit 30 when the rough grinding wheel 306 contacts the contact surface 96 of the block gauge 95 and adding the thickness of the wafer 100. Thereafter, the wafer height measuring device 43 measures the height of the top surface of the wafer 100 before grinding (see Figure 3), and adjustments are made so that this measurement value corresponds to the height of the top surface of the wafer 100 relative to the rough grinding unit 30, thereby ensuring consistency between the height of the rough grinding unit 30 obtained by the encoder 205 and the height of the wafer 100 measured by the wafer height measuring device 43. [Explanation of symbols]

[0097] 1: Grinding device, 5: Chuck table, 6: Turntable, 7: Control unit, 8: fixed column, 10: first device base, 11: second device base, 12: first column, 13: second column, 15: housing, 20: rough grinding feed mechanism, 21: finish grinding feed mechanism, 30: rough grinding unit, 31: finish grinding unit, 41: first measuring mechanism, 42: Holding surface height measuring device, 43: Wafer height measuring device, 45: Second measuring mechanism, 50: holding surface, 51: frame surface, 60: touch panel, 71: origin position calculation unit, 81: First lower surface detection unit, 82: Second lower surface detection unit, 86: Arm portion, 87: Support member, 88: Motor, 90: Detector, 91: Groove portion, 92: Light projecting portion, 93: Light receiving part, 95: Block gauge, 96: Contact surface, 100: wafer, 101: front surface, 103: back surface, 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: conveying pad, 172: carrying mechanism, 173: conveying pad, 200: ball screw, 201: guide rail, 202: motor, 203: lift table, 204: holder, 205: Encoder, 300: Spindle, 301: Spindle housing, 302: spindle motor, 303: wheel mount, 304: grinding wheel, 305: Wheel base, 306: Rough grinding wheel, 307: Finish grinding wheel, 401: Loading / unloading area, 402: Processing area

Claims

1. A grinding device for grinding a workpiece, comprising: a chuck table having a holding surface for holding the workpiece; a grinding unit having a spindle on which a grinding wheel having grinding stones arranged in an annular shape is mounted; a grinding feed mechanism that moves the grinding unit in a direction perpendicular to the holding surface; a bottom surface detection unit that detects the bottom surface of the grinding wheel when the grinding unit is lowered by the grinding feed mechanism; an upper surface detector for detecting the height of the upper surface of the workpiece held on the chuck table; a control unit; the control unit includes an origin position calculation unit that calculates an origin position, which is the height position of the grinding unit when the lower surface of the grinding wheel comes into contact with the upper surface of the workpiece, based on the height position of the grinding unit when the lower surface of the grinding wheel is detected by the lower surface detection unit and the height of the upper surface of the workpiece detected using the upper surface detection unit; the control unit lowers the grinding unit at high speed until the grinding start position is a predetermined distance higher than the origin position of the grinding unit calculated by the origin position calculation unit, and thereafter grinds the workpiece while lowering the grinding unit at a low speed. Grinding equipment.

2. a turntable having a plurality of the chuck tables; the control unit is configured to rotate the turntable to position the chuck table holding the workpiece below the grinding wheel; While the turntable is rotating, the lower surface detection unit detects the lower surface of the grinding wheel when the grinding unit is lowered by the grinding feed mechanism. The grinding device according to claim 1 .

3. A method for grinding a workpiece, in which a workpiece held on a chuck table is ground by a grinding wheel of a grinding unit, comprising: a holding step of holding the workpiece by the chuck table; a bottom surface detection step of detecting a bottom surface of the grinding wheel when the grinding unit is lowered; an upper surface detection step of detecting the height of the upper surface of the workpiece held on the chuck table; an origin position calculation step of calculating an origin position, which is the height position of the grinding unit when the lower surface of the grinding wheel comes into contact with the upper surface of the workpiece, based on the height position of the grinding unit when the lower surface of the grinding wheel is detected in the lower surface detection step and the height of the upper surface of the workpiece detected in the upper surface detection step; a high-speed lowering step of lowering the grinding unit at high speed until the grinding unit reaches a grinding start position that is higher by a predetermined distance than the origin position of the grinding unit calculated in the origin position calculating step; a grinding step of grinding the workpiece while lowering the grinding unit at a low speed after the high-speed lowering step; A method for grinding a workpiece, comprising:

4. A plurality of the chuck tables are arranged on a turntable, a turntable rotating step of rotating the turntable to position the chuck table holding the workpiece in the holding step below the grinding wheel, The lower surface detection step is performed overlapping with the turntable rotation step.

4. The method for grinding a workpiece according to claim 3.

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