Method for cleaning chuck table

Abstract

To provide a method for cleaning a chuck table that can prevent generation of cleaning water which continues to stay on a holding surface of a chuck table during cleaning so as to prevent cutting chips from remaining on the holding surface when discharge of the cleaning water is finished.SOLUTION: A method for cleaning a chuck table 18 by jetting cleaning water through at least a pair of cleaning nozzles 61, 62 to a holding surface 19a constituted on an upper surface of a holding member 19 of the holding table 18 includes: (A) setting a water jetted position P1 of a cleaning water W1 discharged from the one cleaning water nozzle 61 to a center O of the holding surface 19a, and setting a water jetted position P2 of a cleaning water W2 discharged from the other cleaning water nozzle 62 to the vicinity of an outer edge of the holding surface 19a separated away from the center O of the holding surface 19a; and / or (B) discharging the cleaning water W1 from the one cleaning water nozzle 61 and discharging the cleaning water W2 from the other cleaning water nozzle 62 not simultaneously but at different time points.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for cleaning a chuck table having a disk-shaped holding member made of a porous material. [Background technology]

[0002] Conventionally, a grinding device for grinding and thinning a wafer or a package substrate is known, as disclosed in Patent Document 1, for example. The grinding device includes a chuck table for holding the workpiece and a grinding unit for grinding the workpiece, and an annular grinding wheel including a plurality of grindstones is attached to the grinding unit. The workpiece is held by the chuck table, and the grindstones are brought into contact with the workpiece while rotating the chuck table and the grinding wheel, thereby grinding and thinning the workpiece.

[0003] The chuck table has a disk-shaped holding member made of a porous material such as porous ceramics, and the upper surface of the holding member constitutes a holding surface that holds the workpiece. The holding surface is configured to generate negative pressure by sucking air, and adsorbs and holds the workpiece. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-117909 A Summary of the Invention [Problem to be solved by the invention]

[0005] Grinding a workpiece generates grinding chips (machining chips), and if these grinding chips remain on the holding surface of the chuck table, they will be caught between the workpiece and the holding surface when it is held later. In this case, for example, there is a concern that the workpiece may rise locally, preventing uniform thinning and reducing the processing quality.

[0006] In relation to this point, in the past, cleaning was carried out by supplying cleaning water to the holding surface to remove the grinding debris from the holding surface, but there were cases in which the grinding debris would remain on the holding surface and could not be washed off the holding surface.

[0007] In particular, since the holding surface is sucked, once grinding debris remains on the holding surface, it gradually accumulates on the holding surface and firmly adheres to the surface. This raises concerns that the negative pressure on the holding surface may be locally weakened, making it impossible to exert sufficient suction holding power. In addition, there is a concern that the accumulation of grinding debris may cause some areas of the holding surface to rise, reducing the flatness and causing the shape of the holding surface to be distorted.

[0008] In view of the above problems, the present invention proposes a novel technique for cleaning a chuck table having a disk-shaped holding member. [Means for solving the problem]

[0009] The problem to be solved by the present invention has been described above, and the means for solving this problem will now be described.

[0010] According to one aspect of the present invention, there is provided a method for cleaning a chuck table, in which cleaning water is sprayed onto a holding surface formed on an upper surface of a holding member of a chuck table by at least a pair of cleaning nozzles, to clean the holding surface, the method comprising the steps of: (A) The landing position of the cleaning water discharged from one cleaning water nozzle is the center of the holding surface, and the landing position of the cleaning water discharged from the other cleaning water nozzle is near the outer periphery of the holding surface away from the center of the holding surface. and / or (B) A method for cleaning the chuck table in which the discharge of cleaning water from one cleaning water nozzle and the discharge of cleaning water from the other cleaning water nozzle are performed at different times.

[0011] According to another aspect of the present invention, the holding surface is cleaned while being stopped or rotated.

[0012] According to one embodiment of the present invention, the pair of cleaning water nozzles are positioned on either side of a line passing through the center of the holding surface, and the pair of cleaning water nozzles are positioned at positions offset from each other relative to the center within a range of 90 degrees or more and 180 degrees or less.

[0013] According to one aspect of the present invention, the holding member is formed of a porous material, and the holding surface holds the workpiece by negative pressure caused by suction, and suction is stopped during cleaning. Effect of the Invention

[0014] The present invention provides the following advantages. In other words, according to one aspect of the present invention, no cleaning water remains on the holding surface of the chuck table during cleaning, thereby preventing cutting chips from remaining on the holding surface when the cleaning water has been dispensed. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing an example of a grinding device in which the present invention is implemented. [Diagram 2] FIG. 4 is a schematic plan view illustrating a cleaning mechanism for the chuck table. [Diagram 3] FIG. 4 is a schematic side view illustrating a cleaning mechanism for the chuck table. [Figure 4] 1A is a diagram for explaining a cleaning method according to a first embodiment, and FIG. 1B is a diagram for explaining a cleaning method according to the first embodiment. [Diagram 5] 13A and 13B are views for explaining a cleaning method according to a second embodiment; [Figure 6] FIG. 1A is a diagram for explaining a cleaning method in Comparative Example 1. FIG. 1B is a diagram for explaining a cleaning method in Comparative Example 2. FIG. 1C is a diagram for explaining a cleaning method in Comparative Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An embodiment according to one aspect of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a perspective view showing an example of the configuration of a grinding device capable of implementing the present invention.

[0017] As shown in Fig. 1, the grinding device 2 includes a base 4 having a substantially rectangular parallelepiped shape. In Fig. 1, the horizontal direction of the base 4 is the X-axis direction, the vertical direction of the base 4 is the Y-axis direction, and the height direction of the base 4 is the Z-axis direction. Two cassette mounting stages 8a and 8b are provided on one edge of the base 4 in the Y-axis direction (for example, the -Y direction) and aligned in the X-axis direction of the base 4.

[0018] Cassettes 10a and 10b are placed on the cassette placement stages 8a and 8b, respectively. One cassette 10a contains workpieces before processing, and the other cassette 10b contains workpieces after processing. The workpieces are, for example, wafers that require back grinding.

[0019] A recess 4a is provided on the other side of the base 4 in the Y-axis direction (for example, in the +Y direction) of the cassette placement tables 8a, 8b, and a transfer robot 6 that is movable relative to the cassettes 10a, 10b, etc. is provided in this recess 4a. The transfer robot 6 is, for example, configured by a robot hand that holds and transfers the workpiece by vacuum suction.

[0020] A positioning table 12 having a plurality of positioning pins is provided on the base 4 on the other side (e.g., +X direction) of the recess 4a in the X-axis direction. The position of the workpiece transferred from the cassette 10a to the positioning table 12 by the transfer robot 6 is adjusted by the plurality of positioning pins.

[0021] A carry-in arm (loading arm) 14 is provided on one side in the X-axis direction (e.g., −X direction) of the positioning table 12 and on the other side in the Y-axis direction (e.g., +Y direction) of the recess 4a. The carry-in arm 14 is formed of, for example, a robot hand that holds and transports the workpiece by vacuum suction.

[0022] A disk-shaped turntable 16 is disposed on the other side (for example, +Y direction) in the Y-axis direction of the load-in arm 14. The turntable 16 is rotatably provided on the base 4, and a total of three chuck tables 18 are provided on the upper surface of the turntable 16, spaced approximately 120 degrees apart in the circumferential direction. Each chuck table 18 is configured to rotate (spin on its own axis) in a horizontal plane by a drive mechanism (not shown), with a vertical axis passing through the center of each chuck table 18 as the rotation axis.

[0023] One chuck table 18 is disposed in each of the area closest to the loading arm 14 (loading / unloading area A), the area approximately 120 degrees counterclockwise from the loading / unloading area A when viewed from above (rough grinding area B), and the area approximately 120 degrees clockwise from the loading / unloading area A when viewed from above (finish grinding area C).

[0024] The chuck table 18 moves in the direction of the arrow by rotating the turntable 16. For example, the chuck table 18 located in the loading / unloading area A is moved by the turntable 16 counterclockwise in top view to the rough grinding area B and the finish grinding area C in that order, and then moved clockwise and returned to the loading / unloading area A again.

[0025] A holding member 19 made of a porous material is provided on the upper portion of each chuck table 18, and this holding member 19 has an internal suction path (not shown) one end of which is connected to a suction source (not shown) such as an ejector. The other end of the suction path is exposed on the surface of the holding member 19, and negative pressure is generated on the surface of the holding member 19 when the suction source is operated.

[0026] The workpiece whose back side has been sucked by carry-in arm 14 is transported to chuck table 18 located in carry-in / carry-out area A. Thereafter, the suction of carry-in arm 14 is released, and the front side of the workpiece is sucked and held by holding surface 19a of holding member 19 via the protective tape.

[0027] A square pillar-shaped support structure 20a is provided on the other side in the Y-axis direction (e.g., +Y direction) of the turntable 16 so as to protrude to one side in the height direction (e.g., +Z direction) of the base 4. A Z-axis movement mechanism 22 is provided on one surface of the support structure 20a on one side in the Y-axis direction (e.g., -Y direction).

[0028] The Z-axis movement mechanism 22 is provided with a pair of Z-axis guide rails 24 arranged on one surface of the support structure 20a and generally parallel to the Z-axis direction. A Z-axis movement plate 26 is slidably attached to the Z-axis guide rails 24.

[0029] A nut portion (not shown) is provided on the back side of the Z-axis moving plate 26 (one side of the support structure 20a), and a Z-axis ball screw 28 provided along the Z-axis guide rails 24 between a pair of Z-axis guide rails 24 is rotatably connected to this nut portion.

[0030] A Z-axis pulse motor 30 is connected to one end of the Z-axis ball screw 28. When the Z-axis pulse motor 30 rotates the Z-axis ball screw 28, the Z-axis moving plate 26 moves in the Z-axis direction along the Z-axis guide rail 24.

[0031] A support member 32 is provided on the front surface side of the Z-axis moving plate 26. The support member 32 supports a rough grinding unit 34a for grinding (machining) a workpiece. The rough grinding unit 34a includes a cylindrical spindle housing fixed to the support member 32.

[0032] A spindle 36, which serves as a rotation axis parallel to the Z-axis direction, is rotatably accommodated in the spindle housing. A spindle motor 38 is connected to the upper end of the spindle 36.

[0033] The lower end of the spindle 36 is exposed to the outside of the spindle housing, and the upper surface of a disk-shaped wheel mount 40 made of a metal material such as stainless steel is fixed to this lower end. In addition, a disk-shaped rough grinding wheel 42a having roughly the same diameter as the wheel mount 40 is attached to the lower surface of the wheel mount 40.

[0034] The rough grinding wheel 42a has a substantially disk-shaped wheel base made of a metal material such as stainless steel, and a plurality of grinding wheels attached in an annular shape to the underside of the wheel base arranged on the opposite side to the wheel mount 40. Each of the plurality of grinding wheels has a substantially rectangular parallelepiped shape, and is arranged around the entire circumference of the underside of the wheel base with a gap between adjacent grinding wheels.

[0035] The grinding wheel is formed by mixing abrasive grains such as diamond and CBN (cubic boron nitride) with a binder such as metal, ceramics, or resin. However, there is no limitation on the binder or abrasive grains, and they can be appropriately selected according to the specifications of the grinding wheel. The area directly below the rough grinding unit 34a corresponds to the rough grinding area B described above.

[0036] A square pillar-shaped support structure 20b is provided adjacent to one side in the X-axis direction (e.g., the -X direction) of the support structure 20a on which the rough grinding unit 34a is provided. A Z-axis movement mechanism 22 is provided on one surface of the support structure 20b on one side in the Y-axis direction (e.g., the -Y direction) in the same manner as the support structure 20a.

[0037] Further, a finish grinding unit 34b is connected to the Z-axis moving mechanism 22 provided on the support structure 20b via the Z-axis moving plate 26 and the support member 32. The area directly below the finish grinding unit 34b corresponds to the above-mentioned finish grinding area C. The finish grinding unit 34b has a spindle 36, a spindle housing, a spindle motor 38, and a wheel mount 40, similar to the above-mentioned rough grinding unit 34a.

[0038] A disk-shaped finish grinding wheel 42b having approximately the same diameter as the wheel mount 40 is attached to the underside of the wheel mount 40 of the finish grinding unit 34b. The finish grinding wheel 42b has a wheel base and a plurality of grinding stones attached in an annular shape to the underside of the wheel base.

[0039] Each of the grinding wheels has a substantially rectangular parallelepiped shape and is arranged around the entire circumference of the lower surface of the wheel base with a gap between adjacent grinding wheels. The grinding wheels of the finish grinding wheel 42b use abrasive grains with a smaller diameter than the abrasive grains of the rough grinding wheels.

[0040] In the above configuration, the back side of the workpiece is ground in the order of rough grinding and finish grinding. For example, rough grinding is performed at a first spindle rotation speed and a first Z-axis processing feed rate, and finish grinding is performed at a second spindle rotation speed and a second Z-axis processing feed rate. Note that the rotation speed and the Z-axis processing feed rate do not need to be constant values ​​all the time. During grinding, the chuck table 18 rotates at a predetermined speed, and the workpiece is ground while rotating.

[0041] An unloading arm 50 is provided on one side in the X-axis direction (for example, the -X direction) of the carry-in arm 14. The carry-out arm 50 is formed of, for example, a robot hand that holds and transports a workpiece by vacuum suction.

[0042] The unloading arm 50 adsorbs the workpiece and unloads it from the chuck table 18 located in the loading / unloading area A. The unloading arm 50, the above-mentioned loading arm 14, and the transport robot 6 constitute a transport unit 52 that transports the workpiece.

[0043] A spinner cleaning unit 54 for cleaning the workpiece after grinding is provided on one side in the X-axis direction of the carry-out arm 50 (for example, the -X direction) and in a region adjacent to the carry-out arm 50 and the recess 4a in the Y-axis direction. The spinner cleaning unit 54 is configured to include, for example, a spinner table that holds the workpiece and rotates at high speed, a cleaning chamber that houses the spinner table, and a spinner cover that covers the periphery of the cleaning chamber and automatically opens and closes when the workpiece is loaded and unloaded.

[0044] Each mechanism described above is automatically controlled by the controller 3, and the state of control is displayed on the touch panel 5. An operator can operate the touch panel 5 to perform various settings of the grinding device 2.

[0045] 2 is a diagram illustrating a cleaning mechanism 60 for the chuck tables 18. Three chuck tables 18 are provided on the turntable 16, and as the turntable 16 rotates, each chuck table 18 moves in the order of a load / unload area A, a rough grinding area B, and a finish grinding area C.

[0046] Each chuck table 18 has a disk-shaped holding member 19 disposed within a ring-shaped frame 18a, and the surface of the holding member 19 is exposed as a holding surface 19a. Each chuck table 18 is configured to rotate on its own axis by a rotation mechanism (not shown), and the rotation speed is controlled by the controller 3. Each chuck table 18 is connected to a suction source (not shown), and the holding surface 19a is configured as a suction holding surface.

[0047] A cleaning mechanism 60 is provided near the chuck table 18 in the load-in / load-out area A. The cleaning mechanism 60 is configured to include, for example, a pair of cleaning water nozzles 61, 62 installed on the base 4 (FIG. 1), water supply paths 61a, 62a connecting the cleaning water nozzles 61, 62 to a cleaning water supply source 70, and control valves 61c, 62c provided in the water supply paths 61a, 62a.

[0048] Each of the cleaning water nozzles 61, 62 is configured to be installed in a water landing position adjustment mechanism 61d, 62d, so that the water landing positions P1, P2 at which the cleaning water W1, W2 land on the holding surface 19a can be adjusted and fixed. It is also possible to arrange for the cleaning water to land at a predetermined water landing position by the installation angle of each of the cleaning water nozzles 61, 62, etc., without providing the water landing position adjustment mechanisms 61d, 62d. In this case, it is possible to prevent the water landing position from being shifted by any subsequent adjustment work.

[0049] The pair of cleaning water nozzles 61, 62 are arranged, for example, in a plan view, at positions on either side of a straight line passing through the center O of the holding surface 19a of the chuck table 18, so that cleaning water is discharged in a generally V-shape. In this embodiment, the cleaning water nozzles 61, 62 are arranged at positions shifted from each other by 120 degrees with respect to the center O, but this is not particularly limited as long as it is within a range of 90 degrees to 180 degrees. The number of cleaning water nozzles 61, 62 is not limited to two as long as an embodiment of the cleaning method described later can be implemented.

[0050] 3, the discharge ports 61b, 62b of the respective cleaning water nozzles 61, 62 are located above the holding surface 19a, and the cleaning water W1, W2 discharged from the discharge ports 61b, 62b falls and lands on the holding surface 19a. The positions at which the cleaning water W1, W2 lands on the holding surface 19a after being discharged are referred to as water landing positions P1, P2. In other words, the discharged cleaning water W1, W2 lands on the holding surface 19a at the water landing positions P1, P2.

[0051] As shown in Figures 3 and 4(A), the cleaning waters W1 and W2 are discharged to form a continuous linear water flow. The cleaning waters W1 and W2 that land on the holding surface 19a run down along the holding surface 19a to the outside of the holding surface 19a. During this cleaning, suction of the holding surface 19a is stopped to prevent the cleaning waters W1 and W2 and cutting chips from being sucked in, thereby preventing cutting chips from remaining.

[0052] In the above configuration, an embodiment for cleaning the holding surface 19a of the chuck table 18 will be described. This cleaning is performed for the chuck table 18 in the loading / unloading area A in Fig. 3, for example, in a situation where a plurality of workpieces are continuously processed, between the time when the processed workpieces are unloaded and the time when the unprocessed workpieces are loaded. Also, for example, cleaning is performed for a predetermined time at any timing during maintenance when the workpieces are not being processed.

[0053] <First embodiment> In the example of Figure 4(A), the landing position P1 of the cleaning water W1 ejected from one cleaning water nozzle 61 is the center O of the holding surface 19a, and the landing position P2 of the cleaning water W2 ejected from the other cleaning water nozzle 62 is near the outer periphery of the holding surface 19a, away from the center O of the holding surface 19a.

[0054] The example in FIG. 4(A) is an example in which cleaning is performed in a state in which the chuck table 18 is stationary and not rotating. The cleaning water W1 that lands at the water landing position P1 flows from the center O toward the outside in the radial direction. On the other hand, the cleaning water W2 that lands at the water landing position P2 flows toward the center O. The cleaning waters W1 and W2 temporarily stay on the holding surface 19a and accumulate until they cover the entire holding surface 19a, and when a certain amount of the cleaning water W1 and W2 accumulates, they overflow from the holding surface 19a and flow down to the outside of the holding surface 19a. As the cleaning water overflows, the cutting chips K1 on the holding surface 19a are also washed away to the outside of the holding surface 19a. Note that the vicinity of the outer periphery of the holding surface 19a, which is the water landing position P2, can be, for example, a position that is 70% to 100% of the radius of the holding surface 19a.

[0055] The example of FIG. 4(B) is an example in which cleaning is performed by rotating the chuck table 18 in the clockwise direction R in the drawing. The cleaning water W1 that lands on the water landing position P1 flows radially outward from the center O and circumferentially around the center O as the holding surface 19a rotates. On the other hand, the cleaning water W2 that lands on the water landing position P2 flows circumferentially around the center O as the holding surface 19a rotates, while also moving toward the center O. The cleaning waters W1 and W2 flow circumferentially on the holding surface 19a and temporarily stay there until they cover the entire holding surface 19a. When a certain amount of the cleaning water W1 and W2 accumulates, they overflow from the holding surface 19a and flow down to the outside of the holding surface 19a. As the cleaning water flows circumferentially and overflows, the cutting chips K1 on the holding surface 19a are also washed away to the outside of the holding surface 19a.

[0056] In the example of Figure 4 (B), the landing position P1 is the center O, so the cleaning water W1 is guaranteed to land at the center O. Even if the rotation of the chuck table 18 is accelerated, a flow of cleaning water can be formed that flows radially outward from the center O, preventing the creation of areas where the cleaning water does not reach.

[0057] The cleaning shown in Fig. 4(A) and (B) is performed by the controller 3 controlling the opening and closing of the control valves 61c and 62c and the rotation of the chuck table 18 as shown in Fig. 2. The controller 3 may alternate between cleaning with the chuck table 18 stopped as shown in Fig. 4(A) and cleaning with the chuck table 18 rotated as shown in Fig. 4(B). The controller 3 may alternately discharge cleaning water from one cleaning nozzle and the other cleaning nozzle, in addition to simultaneously discharging cleaning water from both cleaning water nozzles 61 and 62. Note that a configuration may be adopted in which only one control valve is provided and cleaning water is branched from the control valve to supply cleaning water to both cleaning water nozzles 61 and 62. After the entire holding surface 19a is thoroughly washed, the control valves 61c and 62c are closed to end the cleaning.

[0058] According to the cleaning in the first embodiment described above, since no cleaning water remains stagnant on the holding surface 19a, it is possible to prevent the cutting chips K1, K2 from remaining on the holding surface 19 when the discharge of the cleaning water is completed.

[0059] Second Embodiment 5(A) and (B), the cleaning water W1 is discharged alternately from the cleaning water nozzle 61 and the cleaning water W2 is discharged from the cleaning water nozzle 62. Note that in this example, cleaning is performed while the chuck table 18 is stationary and not rotating, but cleaning may be performed while the chuck table 18 is rotating.

[0060] 5(A) and (B), the landing position P1 of the cleaning water W1 from the cleaning water nozzle 61 and the landing position P2 of the cleaning water W2 from the cleaning water nozzle 62 are arranged in positions that are line-symmetrical on both sides of a straight line that passes through the center O of the holding surface 19a of the chuck table 18 in a plan view. The landing positions P1 and P2 are, for example, near the outer periphery of the holding surface 19a away from the center O of the holding surface 19a in order to allow the cleaning water to reach a wide range of the holding surface 19a.

[0061] As shown in Fig. 5(A), only cleaning water W1 is supplied from the cleaning water nozzle 61, and the cleaning water W1 that lands on the holding surface 19a flows as it is, discharging the cutting chips K1 outside the holding surface 19a. Similarly, as shown in Fig. 5(B), only cleaning water W2 is supplied from the cleaning water nozzle 62, and the cleaning water W2 that lands on the holding surface 19a flows as it is, discharging the cutting chips K2 outside the holding surface 19a.

[0062] According to the cleaning according to the second embodiment described above, cleaning water is not discharged from the pair of cleaning water nozzles 61, 62 at the same time, and the cleaning water W1, W2 discharged from both cleaning water nozzles 61, 62 collide with each other and continue to remain on the holding surface 19a. Since no cleaning water continues to remain, it is possible to prevent cutting chips K1, K2 from remaining on the holding surface 19a when the discharge of the cleaning water is completed.

[0063] 5(A) and (B), as shown in FIG. 2, the cleaning shown in FIG. 5(A) and (B) is performed by the controller 3 controlling the opening and closing of the control valves 61c, 62c and the rotation of the chuck table 18. For example, the controller 3 opens one of the control valves 61c, 62c and closes the other to discharge cleaning water W1 only from one of the cleaning water nozzles 61, and then switches the opening and closing of the control valves 61c, 62c after a predetermined time has elapsed to discharge cleaning water W2 only from the other cleaning water nozzle 62. By repeating the opening and closing of the control valves 61c, 62c several times, the entire holding surface 19a is thoroughly cleaned, and then the cleaning is terminated by closing the control valves 61c, 62c.

[0064] <Comparative Example 1> 6A shows an example of Comparative Example 1 in which a pair of cleaning water nozzles 61, 62 and water landing positions P1, P2 are arranged at positions that are symmetrical on both sides of a line passing through the center O of the holding surface 19a. In this case, when cleaning is performed while rotating the chuck table 18, a retention area T1 is formed in which the cleaning water rotates at the same location. It was confirmed that the cutting chips K1, K2 that entered this retention area T1 continue to move within the retention area T1 and do not flow out of the retention area T1. After cleaning is completed, the cutting chips K1, K2 remain in the retention area T1.

[0065] <Comparative Example 2> Fig. 6(B) shows the behavior of Comparative Example 2 when the rotation speed of the chuck table 18 is increased compared to Comparative Example 1 in Fig. 6(A). In this case, the so-called centrifugal force acts strongly, and the cleaning water flows away from the center O of the holding surface 19a, that is, it cannot flow toward the center O, and a non-reach area T2 where the cleaning water does not reach the center of the holding surface 19a is formed. Then, it was confirmed that the cleaning water does not reach the cutting chips K1 and K2 that have entered the non-reach area T2, and they do not flow out of the non-reach area T2. Then, when cleaning is completed, the cutting chips K1 and K2 remain in the non-reach area T2.

[0066] <Comparative Example 3> Fig. 6(C) shows the behavior of Comparative Example 3 when cleaning is performed without rotating the chuck table 18, as compared to Comparative Example 1 in Fig. 6(A). In this case, a retention area T3 is formed where cleaning water discharged simultaneously collides with each other and remains there. It was confirmed that the cutting chips K1 and K2 that entered this retention area T3 continue to move within the retention area T3 and do not flow out of the retention area T3. After cleaning was completed, the cutting chips K1 and K2 remained in the retention area T3.

[0067] If the cutting chips K1, K2 remain as in Comparative Examples 1 to 3 above, when the workpiece is later sucked and held by the holding surface, the cutting chips K1, K2 will be sucked into the holding surface as contaminants, and the cutting chips generated each time cleaning is repeated will gradually accumulate as contaminants.

[0068] The present invention was completed after discovering, observing, and examining the behaviors shown in Comparative Examples 1 to 3, and was not completed by simply setting the water landing position or the timing of discharge. In other words, without the discovery of the behaviors in Comparative Examples 1 to 3, there would have been no motivation to arrive at the present invention, and in light of this point, the present invention cannot be easily achieved.

[0069] The configuration of the present invention described above, as shown in FIGS. 2 to 5, A cleaning method for a chuck table 18, comprising the steps of: applying cleaning water to a holding surface 19a formed on an upper surface of a holding member 19 of the chuck table 18 by at least a pair of cleaning nozzles 61, 62 to clean the holding surface 19a, (A) The landing position P1 of the cleaning water W1 discharged from one cleaning water nozzle 61 is the center O of the holding surface 19a, and the landing position P2 of the cleaning water W2 discharged from the other cleaning water nozzle 62 is near the outer periphery of the holding surface 19a away from the center O of the holding surface 19a. and / or (B) The cleaning water W1 is discharged from one cleaning water nozzle 61 and the cleaning water W2 is discharged from the other cleaning water nozzle 62 at different times, rather than simultaneously. This is what we intend to do.

[0070] As a result of the above, no cleaning water remains on the holding surface 19a of the chuck table 18 during cleaning, so that cutting chips K1, K2 can be prevented from remaining on the holding surface 19 when the cleaning water has been discharged. [Explanation of symbols]

[0071] 2 Grinding equipment 16 Turntable 18 Chuck table 18a Frame 19 Retaining member 19a Retaining surface 60 Cleaning mechanism 61 Cleaning water nozzle 62 Cleaning water nozzle 61a Water supply route 62a Water supply route 61c Control valve 62c Control valve 61d Water landing position adjustment mechanism 62d Water landing position adjustment mechanism 61b Discharge port 62b Discharge port 70 Washing water supply source A Loading / unloading area B Rough grinding area C Grinding area O center K1 cutting waste K2 cutting waste P1 Landing position P2 Landing position W1 Cleaning water W2 cleaning water

Claims

1. A method for cleaning a chuck table, comprising the steps of: applying cleaning water to a holding surface formed on an upper surface of a holding member of the chuck table by at least a pair of cleaning nozzles to clean the holding surface, the method comprising the steps of: (A) the landing position of the cleaning water discharged from one cleaning water nozzle is the center of the holding surface, and the landing position of the cleaning water discharged from the other cleaning water nozzle is near the outer circumferential edge of the holding surface away from the center of the holding surface, and / or (B) The discharge of cleaning water from one cleaning water nozzle and the discharge of cleaning water from the other cleaning water nozzle are performed at different times. How to clean the chuck table.

2. The support surface is cleaned while being stopped or rotated.

2. The method for cleaning a chuck table according to claim 1.

3. 3. The method for cleaning a chuck table according to claim 1, wherein the pair of cleaning water nozzles are arranged on either side of a line passing through a center of the holding surface, and the pair of cleaning water nozzles are arranged at positions offset from each other by a range of 90 degrees or more and 180 degrees or less from the center.

4. The holding member is made of a porous material, and the holding surface holds the workpiece by negative pressure caused by suction.

3. The method for cleaning a chuck table according to claim 1, wherein suction is stopped during cleaning.

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