Foreign object removal methods

Abstract

To provide a foreign matter removal method capable of effectively removing a foreign matter clogging an outer peripheral part of a porous plate of a chuck table.SOLUTION: Fluid is jetted from an outer peripheral part of a porous plate in a state where a portion in an inner side than the outer peripheral part of the porous plate is covered with a pressing member. In this case, most of the fluid supplied from a fluid supply source passes the outer peripheral part of the porous plate. Therefore, in this case, it is possible to effectively remove a foreign matter clogging the outer peripheral part of the porous plate of the chuck table.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a foreign matter removal method for removing foreign matter clogged in the outer peripheral portion of the porous plate of a chuck table.

Background Art

[0002] Chips of devices such as ICs (Integrated Circuits) are essential components in various electronic devices such as mobile phones and personal computers. Such chips are manufactured, for example, in the following order.

[0003] First, a plurality of devices are formed by performing photolithography or the like to form a large number of elements on the surface of a workpiece such as a wafer. Next, the back side of the workpiece is ground to thin the workpiece. Next, the workpiece is cut along the boundaries of the plurality of devices to divide the workpiece into a plurality of chips.

[0004] In a processing apparatus such as a grinding apparatus for grinding a workpiece or a cutting apparatus for cutting a workpiece, the workpiece is processed while being held by a chuck table. This chuck table generally includes a frame body in which a recess is formed and a porous plate fixed in this recess.

[0005] Further, a flow path communicating with the porous plate is formed in the frame body, and this flow path can communicate with a suction source such as an ejector. In the processing apparatus, the workpiece is sucked and held by the chuck table by operating the suction source in a state where the porous plate and the workpiece are in contact with each other.

[0006] Further, when the workpiece is processed in the processing apparatus, the workpiece is heated due to the friction between the cutting tool and the workpiece, and chips (processing chips) of the removed workpiece are generated. When the workpiece is heated and / or the processing chips adhere to the workpiece, the workpiece may be damaged and / or the quality of the chips manufactured from the workpiece may deteriorate.

[0007] Therefore, in processing equipment, the workpiece is often processed with a liquid such as pure water (processing fluid) supplied to the contact interface (processing point) between the processing tool and the workpiece. In this process, the workpiece is sucked in by a chuck table. As a result, foreign matter such as processing chips carried by the processing fluid can enter the gap between the workpiece and the porous plate, clogging the porous plate.

[0008] Furthermore, if foreign matter becomes lodged in the porous plate, the suction force acting on the workpiece may weaken. Therefore, in such processing equipment, a process to remove foreign matter lodged in the porous plate is sometimes performed periodically (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2015-36173 [Overview of the project] [Problems that the invention aims to solve]

[0010] In machining equipment, the porous plate of the chuck table is often able to communicate not only with a suction source but also with a fluid supply source via a channel formed in the frame. In this case, supplying fluid to the porous plate after machining the workpiece makes it easy to separate the workpiece from the porous plate. Furthermore, fluid may also be supplied to the porous plate to remove foreign matter that has become lodged in it.

[0011] In this case, foreign matter that enters the gap between the workpiece and the chuck table often clogs the outer periphery of the porous plate without reaching the center. When fluid is supplied to such a porous plate from a fluid supply source, the amount of fluid passing through the center of the porous plate increases, while the amount of fluid passing through the outer periphery decreases.

[0012] Therefore, in such cases, there is a risk that foreign matter lodged around the outer periphery of the porous plate cannot be adequately removed. In view of this, the object of the present invention is to provide a foreign matter removal method that can effectively remove foreign matter lodged around the outer periphery of the porous plate of a chuck table. [Means for solving the problem]

[0013] According to the present invention, a foreign matter removal method for removing foreign matter stuck on the outer periphery of a porous plate of a chuck table, comprising a frame having a bottom wall and side walls erected from the outer periphery of the bottom wall, wherein a flow path capable of selectively communicating with a suction source or a fluid supply source is formed in the bottom wall, and a porous plate fixed in a recess defined by the bottom wall and the side walls, wherein the flow path is communicated with the suction source to suction and hold a workpiece placed on the porous plate, comprising an arrangement step of positioning a pressing member on the porous plate such that the portion of the porous plate inside the outer periphery of the porous plate is covered and the outer periphery of the porous plate is exposed, and an ejection step of ejecting fluid from the outer periphery of the porous plate by communicating the flow path with the fluid supply source while the porous plate and the pressing member are pressed against each other, The pressing member includes one made of a wafer and / or resin. A method for removing foreign matter is provided. [Effects of the Invention]

[0014] In this invention, the portion of the porous plate inside the outer periphery is covered by a pressing member, and fluid is ejected from the outer periphery of the porous plate. That is, in this invention, most of the fluid supplied from the fluid supply source passes through the outer periphery of the porous plate. Therefore, in this invention, it is possible to effectively remove foreign matter that has accumulated on the outer periphery of the porous plate of the chuck table. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a schematic perspective view showing an example of a grinding apparatus. [Figure 2] Figure 2 is a schematic perspective view showing an example of a workpiece. [Figure 3]FIG. 3 is a diagram schematically showing a chuck table and components communicable with the chuck table. [Figure 4] FIG. 4 is a partial cross-sectional side view schematically showing the tip of a spindle or the like. [Figure 5] FIG. 5 is a diagram schematically showing a state where rough grinding or finish grinding is performed on the upper surface side of a workpiece. [Figure 6] FIG. 6 is a partial cross-sectional side view schematically showing a transfer unit. [Figure 7] FIG. 7 is a flowchart schematically showing an example of a foreign matter removal method for removing foreign matter clogged in the outer peripheral portion of a porous plate of a chuck table. [Figure 8] FIG. 8 is a diagram schematically showing a state of an arrangement step. [Figure 9] FIG. 9 is a diagram schematically showing a state of an ejection step.

Embodiments for Carrying Out the Invention

[0016] Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing an example of a grinding apparatus. The X-axis direction (left-right direction) and Y-axis direction (front-back direction) shown in FIG. 1 are directions orthogonal to each other on a horizontal plane, and the Z-axis direction (up-down direction) is a direction (vertical direction) orthogonal to the X-axis direction and Y-axis direction.

[0017] The grinding apparatus 2 shown in FIG. 1 includes a base 4 that supports or houses each component. On the upper surface of the front end portion of the base 4, a pair of cassette placement areas 6a and 6b are provided. And on each of the cassette placement areas 6a and 6b, cassettes 8a and 8b that can accommodate a plurality of workpieces in a state of being separated from each other in the Z-axis direction are placed.

[0018] That is, each of the cassettes 8a and 8b is provided with a plurality of storage areas in multiple stages capable of accommodating the workpiece. FIG. 2 is a perspective view schematically showing an example of the workpiece accommodated in the cassettes 8a and 8b. The workpiece 11 shown in FIG. 2 has, for example, a circular front surface 11a and a back surface 11b, and is a wafer with a diameter of 8 inches (200 mm) made of a semiconductor material such as silicon (Si).

[0019] This workpiece 11 is partitioned into a plurality of regions by a plurality of division planned lines 13 set in a grid pattern, and devices 15 such as ICs are formed on the front surface 11a side of each region. Further, the workpiece 11 may include a film-like tape provided so as to cover the device 15. This tape has a diameter approximately equal to the diameter of the wafer on which the device 15 is formed, and is made of, for example, resin.

[0020] And this tape protects the device 15 by alleviating the impact applied to the front surface 11a side when grinding the back surface 11b side of the workpiece 11. Note that there is no limitation on the material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may include other semiconductor materials, ceramics, resins, or metals.

[0021] Also, as shown in FIG. 1, a depression 4a is formed behind the cassette placement areas 6a and 6b, and a transfer unit 10 is provided inside this depression 4a. This transfer unit 10 is used to carry out the workpiece 11 before grinding from any one of the plurality of storage areas (original storage area) of the cassettes 8a and 8b, and also to carry in the workpiece 11 after grinding, for example, into the original storage area.

[0022] Specifically, the transfer unit 10 has, for example, a plurality of joints and a robot hand, and holds the workpiece 11 on one surface of this robot hand. Further, the transfer unit 10 can also invert the robot hand holding the workpiece 11, that is, invert the top and bottom of the workpiece 11.

[0023] Furthermore, a position adjustment mechanism 12 for adjusting the position of the workpiece 11 is provided diagonally behind the recess 4a. This position adjustment mechanism 12 includes a disc-shaped position adjustment table and a plurality of pins arranged around the position adjustment table. The workpiece 11, which has been discharged from the cassettes 8a and 8b by the transport unit 10, is then placed on this position adjustment table and its center is aligned to a predetermined position.

[0024] Specifically, the workpiece 11 is brought into the position adjustment table with its back surface 11b facing upwards. Then, multiple pins approach the position adjustment table along its radial direction. As a result, the multiple pins come into contact with the side surface of the workpiece 11, causing it to move slightly. Consequently, the center of the workpiece 11 is aligned to a predetermined position.

[0025] Furthermore, a transport unit 14 is provided to the side of the position adjustment mechanism 12 to hold the workpiece 11 and transport it to the rear. This transport unit 14 includes, for example, a support shaft extending along the Z-axis direction, an arm whose base end is fixed to the upper end of the support shaft and which extends in a direction perpendicular to the Z-axis direction, and a suction pad fixed to the underside of the tip of the arm.

[0026] Furthermore, the support shaft of the transport unit 14 is connected to a motor. When this motor is operated, the support shaft rotates with a straight line along the Z-axis as its axis of rotation. In addition, the support shaft of the transport unit 14 is connected to, for example, a ball screw type moving mechanism (not shown). When this moving mechanism is operated, the support shaft moves along the Z-axis, that is, the support shaft moves up and down.

[0027] For example, the transport unit 14 holds the workpiece 11 and transports it backward in the following order: First, the support shaft is rotated so that the suction pad is positioned directly above the workpiece 11, whose center has been aligned to a predetermined position in the position adjustment mechanism 12. Next, the support shaft is lowered so that the suction pad comes into contact with the back surface (top surface) 11 of the workpiece 11.

[0028] Next, the workpiece 11 is held in place by suction from the back (top) 11b side using the suction pad. Then, the support shaft is raised to raise the suction pad that holds the workpiece 11. Next, the support shaft is rotated to swivel the suction pad that holds the workpiece 11. As a result, the workpiece 11 is transported backward.

[0029] A turntable 16 is provided behind the transport unit 14. This turntable 16 is connected to a motor. When this motor is operated, the turntable 16 rotates with a rotation axis that passes through the center of the upper surface of the turntable 16 and is aligned with the Z-axis direction.

[0030] Furthermore, the turntable 16 is provided with three disc-shaped table bases (not shown) at approximately equal angular intervals along the circumferential direction of the turntable 16. In addition, a chuck table 18 is mounted on top of each table base via bearings or the like. This chuck table 18 is a table capable of holding, for example, a wafer with a diameter of 8 inches (for example, a workpiece 11).

[0031] Figure 3 is a schematic diagram showing a chuck table 18 and components that can communicate with the chuck table 18. The chuck table 18 has a disc-shaped frame 20 made of, for example, ceramics.

[0032] The frame 20 has a disc-shaped bottom wall 20a and cylindrical side walls 20b that rise from the outer circumference of the bottom wall 20a. That is, a disc-shaped recess is formed on the upper surface of the frame 20, defined by the bottom wall 20a and the side walls 20b. A disc-shaped porous plate 22 made of porous ceramics or the like is fixed in this recess.

[0033] The outer diameter of the frame 20 is slightly larger than 8 inches, and its inner diameter (the diameter of the porous plate 22) is slightly smaller than 8 inches. For example, the diameter of the porous plate 22 is 197 mm. The upper surfaces of the side walls 20b of the frame 20 and the upper surface of the porous plate 22 are shaped to correspond to the sides of a cone and function as holding surfaces for holding the workpiece 11.

[0034] Furthermore, a flow path 20c is formed in the bottom wall 20a, which opens at the bottom surface of the recess and penetrates the bottom wall 20a. This flow path 20c is connected to the suction source 26 via valve 24a and to the fluid supply source 28 via valve 24b.

[0035] The suction source 26 includes, for example, an ejector. The fluid supply source 28 includes, for example, a tank for storing high-pressure gas, a filter for removing foreign matter mixed in with the gas supplied from the tank, and a regulator for adjusting the pressure of the gas supplied from the tank.

[0036] Furthermore, the chuck table 18 is connected to a rotating mechanism (not shown). This rotating mechanism includes, for example, a motor and pulleys. When this rotating mechanism operates, the chuck table 18 rotates around a straight line passing through the center of the holding surface of the chuck table 18 as the axis of rotation.

[0037] Furthermore, the chuck table 18 is connected to a tilt adjustment mechanism (not shown) via a table base. This tilt adjustment mechanism includes two movable axes and one fixed axis, which are arranged at approximately equal angular intervals along the circumferential direction of the chuck table 18. When at least one of the two movable axes partially raises or lowers the table base and the chuck table 18, the tilt of the rotation axis of the chuck table 18 is adjusted.

[0038] Furthermore, when the turntable 16 is rotated with the chuck table 18 mounted on the table base, the chuck table 18 moves together with the table base. Specifically, in this case, the table base and the chuck table 18 move along the circumferential direction of the turntable 16.

[0039] This allows the table base and chuck table 18 to be positioned sequentially at, for example, the loading / unloading position A adjacent to the transport unit 14, the rough grinding position B diagonally behind the loading / unloading position, and the finish grinding position C to the side of the rough grinding position (see Figure 1).

[0040] Then, the workpiece 11, which has been transported to the rear by the transport unit 14, is loaded onto the chuck table 18 positioned at loading / unloading position A. For example, the loading of the workpiece 11 onto the chuck table 18 is carried out in the following order.

[0041] First, the support shaft connected to the support shaft of the transport unit 14 is lowered so that the workpiece 11, which is held by the suction pad of the transport unit 14 on its back (top) side 11b, approaches the holding surface of the chuck table 18. Next, the suction of the back (top) side 11b of the workpiece 11 by the suction pad is stopped. As a result, the workpiece 11 separates from the suction pad and is transported to the chuck table 18.

[0042] Next, the suction source 26 is operated and the valve 24a is opened so that the surface (bottom) 11a side of the workpiece 11 is sucked into and held by the chuck table 18. Then, the turntable 16 is rotated so that the chuck table 18 holding the workpiece 11 is positioned at the rough grinding position B.

[0043] A columnar support structure 30 is provided behind both the rough grinding position B and the finish grinding position C. A moving mechanism 32 is provided on the front side of each support structure 30. This moving mechanism 32 comprises a pair of guide rails 34 that extend along the Z-axis direction. Furthermore, a moving plate 36 is attached to the pair of guide rails 34 in a slidable manner.

[0044] Furthermore, a ball screw nut (not shown) is fixed to the rear side of the movable plate 36, and a screw shaft 38 extending along the Z-axis direction is rotatably connected to this nut. This nut also houses a number of balls that roll on the surface of the screw shaft 38 in response to the rotation of the screw shaft 38.

[0045] Furthermore, a motor 40 is connected to one end (the upper end) of the screw shaft 38. When the motor 40 rotates the screw shaft 38, numerous balls circulate inside the nut, causing the movable plate 36 to move along the Z-axis direction along with the nut.

[0046] Furthermore, a grinding unit 42 is provided on the front (surface) of the movable plate 36. This grinding unit 42 includes a spindle housing 44 fixed to the movable plate 36. In addition, a spindle (not shown in Figure 1) extending along the Z-axis direction or a direction slightly inclined with respect to the Z-axis direction is rotatably housed in the spindle housing 44.

[0047] Figure 4 is a schematic cross-sectional side view showing the tip (lower end) of this spindle. The tip of this spindle 46 is exposed from the lower end surface of the spindle housing 44, and a disc-shaped mount 48 is fixed to this lower end.

[0048] A grinding wheel 50a for rough grinding is mounted on the underside of the mount 48 of the grinding unit 42 on the rough grinding position B side. Similarly, a grinding wheel 50b for finish grinding is mounted on the underside of the mount 48 of the grinding unit 42 on the finish grinding position C side.

[0049] Each grinding wheel 50a, 50b includes an annular wheel base 52 made of a metal such as stainless steel or aluminum. Multiple grinding wheels 54 are fixed to the underside of the wheel base 52 at approximately equal angular intervals along the circumferential direction of the wheel base 52.

[0050] Each of the multiple grinding wheels 54 contains a binder such as a vitrified or resinoid, and abrasive grains such as diamond dispersed in this binder. The average particle size of the abrasive grains contained in the grinding wheel 54 of the grinding wheel 50b for finish grinding is smaller than the average particle size of the abrasive grains contained in the grinding wheel 54 of the grinding wheel 50a for rough grinding.

[0051] Furthermore, grinding fluid supply units 56a and 56b are provided near the grinding wheels 50a and 50b. These grinding fluid supply units 56a and 56b include, for example, nozzles 58a and 58b located inside the grinding wheels 50a and 50b in a plan view, and a pump (not shown) that supplies a liquid (grinding fluid) such as pure water to these nozzles 58a and 58b.

[0052] When this pump operates, grinding fluid is supplied from nozzles 58a, 58b to the back (top) surface 11b of the workpiece 11 held on the chuck table 18 positioned at the rough grinding position B or the finish grinding position C. In addition, in the grinding fluid supply units 56a, 56b, grinding fluid may be supplied via the flow channels formed in the grinding wheels 50a, 50b instead of, or in addition to, the nozzles 58a, 58b.

[0053] Furthermore, a motor 60 is connected to the base end (upper end) of the spindle 46 (see Figure 1). When this motor 60 is operated, the mount 48 and grinding wheels 50a and 50b rotate together with the spindle 46, with the axis of rotation being a straight line in the Z-axis direction or slightly inclined with respect to the Z-axis direction.

[0054] Furthermore, when the chuck table 18 that holds the workpiece 11 is positioned at the rough grinding position B or the finish grinding position C, rough grinding or finish grinding is performed on the back (top) surface 11b of the workpiece 11.

[0055] Figure 5 schematically shows how rough grinding or finish grinding is performed on the back (top) 11b side of the workpiece 11. When rough grinding or finish grinding is performed on the back (top) 11b side of the workpiece 11, first, the rotating mechanism and motor 60 connected to the chuck table 18 are operated to rotate both the chuck table 18 and the grinding wheels 50a and 50b.

[0056] Next, while keeping both the chuck table 18 and the grinding wheels 50a and 50b rotating, the moving mechanism 32 (specifically, the motor 40) is operated to bring the multiple grinding wheels 54 into contact with the workpiece 11. That is, while keeping both the chuck table 18 and the grinding wheels 50a and 50b rotating, the grinding wheels 50a and 50b are lowered until the workpiece 11 and the multiple grinding wheels 54 come into contact.

[0057] Furthermore, the grinding fluid supply units 56a and 56b are operated so that grinding fluid L is supplied to the workpiece 11 immediately before it comes into contact with the multiple grinding wheels 58. As a result, the back surface 11b (top surface) of the workpiece 11 is roughly or finish-ground while the liquid is supplied to the contact interface (machining point) between the workpiece 11 and the multiple grinding wheels 58.

[0058] Then, once the rough grinding and finish grinding of the back (top) 11b side of the workpiece 11 are completed, the turntable 16 is rotated so that the chuck table 18 that holds the workpiece 11 is positioned at the loading / unloading position A.

[0059] As shown in Figure 1, a transport unit 62 is provided in front of the loading / unloading position A and to the side of the transport unit 14 to hold the workpiece 11 and transport it forward. Figure 6 is a schematic partial cross-sectional side view of the transport unit 62. This transport unit 62 has a holding mechanism 64 for holding the back (top) 11b side of the workpiece 11.

[0060] The holding mechanism 64 has a disc-shaped frame 64a made of a metal material such as aluminum. A recess with a circular bottom surface is formed on the lower surface of this frame 64a, and a disc-shaped porous plate 64b made of porous ceramics or the like is fixed to this recess. In addition, a plurality of screw holes are formed on the upper surface of the frame 64a, and a bolt 66 is screwed into each of these screw holes.

[0061] Specifically, the bolt 66 has a cylindrical shaft portion extending along the Z-axis direction, and a hexagonal prism-shaped head portion that is larger in diameter than the shaft portion and shorter in length along the Z-axis direction. Furthermore, the shaft portion has a lower part (threaded portion) where threads are formed and an upper part (cylindrical portion) where threads are not formed. The threaded portion of the bolt 66 is screwed into a threaded hole formed on the upper surface side of the frame 64a.

[0062] Furthermore, a through-hole is formed on the upper side of the frame 64a, which communicates with the porous plate 64b. This through-hole can be selectively connected to a suction source such as an ejector (not shown) or an air supply source such as a cylinder (not shown) via piping (not shown) and a valve (not shown).

[0063] Then, when the suction source is operated with the back surface 11b of the workpiece 11 in contact with the lower surface (holding surface) of the porous plate 64b, the back surface (upper surface) 11b of the workpiece 11 is sucked into the holding mechanism 64 and held. Also, when the air supply source is operated while the through holes formed on the upper surface of the frame 64a are under negative pressure, air is supplied to these through holes, bringing the pressure back to normal, making it easier to separate the workpiece 11 from the holding mechanism 64.

[0064] A disc-shaped support member 68 is provided above the holding mechanism 64. This support member 68 has multiple through holes that penetrate the support member 68 in the thickness direction, each with a circular cross-section.

[0065] These through holes are positioned to overlap with multiple screw holes formed on the upper surface of the frame 64a, and the cylindrical portion of a bolt 66 passes through each through hole. Furthermore, the diameter of the bolt 66 head is larger than the diameter of the through hole. Therefore, the bolt 66 will not fall through the through hole.

[0066] Furthermore, a compression coil spring 70 is provided around the portion of the bolt 66's shaft that is located between the frame 64a and the support member 68. In other words, this portion is located inside the compression coil spring 70. The frame 64a and the support member 68 are then subjected to a reaction force generated by compressing the compression coil spring 70.

[0067] Furthermore, the tip of the arm 72 is connected to the side of the support member 68. This arm 72 extends in a direction perpendicular to the Z-axis direction, and its base end is fixed to the upper end of the support shaft 74, which extends in the Z-axis direction. The lower end of the support shaft 74 is connected to the motor 76.

[0068] When the motor 76 is operated, the support shaft 74 rotates with a straight line along the Z-axis as the axis of rotation, that is, the holding mechanism 64 pivots. The support shaft 74 and the motor 76 are connected to the moving mechanism 78. This moving mechanism 78 has a moving plate 78a whose surface is fixed to the side of the motor 76.

[0069] Nuts 78b, which house a number of balls, are fixed to the back side of the movable plate 78a. A screw shaft 78c, which extends along the Z-axis direction, is screwed into this nut 78b. The screw shafts 78c are provided between a pair of guide rails (not shown), each extending along the Z-axis direction, and the movable plate 78a is attached to the front side of this pair of guide rails in a slidable manner.

[0070] Furthermore, a motor 78d is connected to the base (lower) end of the screw shaft 78c. When the motor 78d rotates the screw shaft 78c, numerous balls circulate within the nut 78b, causing the movable plate 78a and the holding mechanism 64, etc., to move along the Z-axis direction together with the nut 78b.

[0071] Then, when the chuck table 18 that holds the workpiece 11 after grinding is positioned at loading / unloading position A, the transport unit 62 unloads the workpiece 11 from the chuck table 18. For example, the unloading of the workpiece 11 from the chuck table 18 is performed in the following order.

[0072] First, the operation of the suction source 26 is stopped, and the valve 24a is closed. Next, the fluid supply source 28 is operated, and the valve 24b is opened, so that the flow path 20c formed in the frame 20 of the chuck table 18 becomes atmospheric pressure.

[0073] Next, the motor 76 is operated to rotate the holding mechanism 64 so that it is positioned directly above the workpiece 11 placed on the chuck table 18. Then, the motor 78d of the moving mechanism 78 is operated to lower the holding mechanism 64 so that the lower surface of the porous plate 64b of the holding mechanism 64 comes into contact with the back surface (top surface) 11b of the workpiece 11.

[0074] Next, the suction source communicating with the porous plate 64b is activated so that the back (top) 11b side of the workpiece 11 is attracted to and held by the holding mechanism 64. Next, the motor 78d of the moving mechanism 78 is activated to raise the holding mechanism 64 so that the workpiece 11 is discharged from the chuck table 18. Next, the motor 76 is activated to rotate the holding mechanism 64 that holds the workpiece 11. As a result, the workpiece 11 is transported forward.

[0075] As shown in Figure 1, a cleaning device 80 for cleaning the workpiece 11 that has been unloaded from the chuck table 18 is provided on the side of the transport unit 62. This cleaning device 80 includes, for example, a spinner table for holding the front (bottom) 11a side of the workpiece 11, and a cleaning unit including a nozzle for supplying a liquid (cleaning solution) such as pure water to the back (top) 11b side of the workpiece 11 held by the spinner table.

[0076] This spinner table has a structure similar to the chuck table 18 shown in Figure 1, and is connected to a motor, etc. When this motor is operated, the spinner table rotates with a rotation axis that passes through the center of the upper surface of the spinner table and is aligned with the Z-axis direction.

[0077] Then, the workpiece 11, which has been unloaded from the chuck table 18 by the transport unit 62, is loaded onto the spinner table. For example, the loading of the workpiece 11 onto the spinner table is carried out in the following order.

[0078] First, the motor 76 is operated to rotate the holding mechanism 64 so that it is positioned directly above the spinner table. Next, the motor 78d of the moving mechanism 78 is operated to lower the holding mechanism 64 so that the surface (bottom surface) 11a of the workpiece 11 is brought closer to the holding surface of the spinner table.

[0079] Next, the operation of the suction source communicating with the porous plate 64b of the holding mechanism 64 is stopped. Then, the air supply source communicating with the porous plate 64b of the holding mechanism 64 is activated to separate the workpiece 11 from the holding mechanism 64. This completes the loading of the workpiece 11 onto the spinner table.

[0080] In this cleaning device 80, the workpiece 11 is cleaned by supplying cleaning fluid from a cleaning unit to the back surface (top surface) 11b of the workpiece 11 while rotating a spinner table that holds the front surface (bottom surface) 11a side of the workpiece 11. Once the cleaning of the workpiece 11 in the cleaning device 80 is complete, the transport unit 10 carries the workpiece 11 from the cleaning device 80 to one of the multiple storage areas (for example, the original storage area) of the cassettes 8a and 8b.

[0081] In the grinding apparatus 2 described above, rough grinding or finish grinding is performed on the back (top) 11b side of the workpiece 11 with the suction source 26 operating and the valve 24a in the open state (see Figure 5). As a result, foreign matter such as grinding chips may enter the gap between the surface (bottom) 11a of the workpiece 11 and the holding surface of the chuck table 18 due to the grinding fluid L, and clog the outer circumference of the porous plate 22.

[0082] Figure 7 is a schematic flowchart illustrating an example of a foreign matter removal method for removing foreign matter stuck in the outer periphery of the porous plate 22 of the chuck table 18. In this method, first, a pressing member is placed on the porous plate 22 (placement step: S1).

[0083] Figure 8 schematically shows the arrangement step (S1). The pressing member 21 placed on the porous plate 22 is, for example, a wafer with a diameter of 6 inches (150 mm) made of a semiconductor material such as silicon (Si), having a circular surface 21a and a back surface 21b.

[0084] Furthermore, the pressing member 21 is a wafer on which the device 15 shown in Figure 2 is not formed, a so-called mirror wafer. The pressing member 21 may also include a film-like tape provided to cover the front and / or back surface of the mirror wafer. This tape has a diameter approximately equal to the diameter of the mirror wafer and is made of, for example, resin.

[0085] The pressing member 21 is positioned on the porous plate 22, for example, by manually aligning the center of the pressing member 21 with the center of the porous plate 22. Alternatively, the pressing member 21 may be housed in the cassettes 8a and 8b shown in Figure 1 and positioned on the porous plate 22 using the transport units 10 and 14 described above.

[0086] When the pressing member 21 is placed on the porous plate 22, the portion of the porous plate 22 inside the outer periphery is covered, while the outer periphery of the porous plate 22 is exposed. In the placement step (S1), the operation of both the suction source 26 and the fluid supply source 28 is stopped, and the valves 24a and 24b are closed.

[0087] Next, with the porous plate 22 and the pressing member 21 pressed against each other, fluid is ejected from the outer periphery of the porous plate 22 (ejection step: S2). Figure 9 is a schematic diagram showing the ejection step (S2). This ejection step (S2) is carried out, for example, in the following order.

[0088] First, the turntable 16 is rotated so that the chuck table 18, which is included in the porous plate 22 on which the pressing member 21 is placed, is positioned at the loading / unloading position A. Note that if the pressing member 21 is placed on the porous plate 22 with the chuck table 18 already positioned at the loading / unloading position A, it is not necessary to rotate the turntable 16.

[0089] Next, the motor 76 is operated to rotate the holding mechanism 64 so that it is positioned directly above the pressing member 21. Then, the motor 78d of the moving mechanism 78 is operated to lower the holding mechanism 64 so that the pressing member 21 is pressed by the porous plate 64b of the holding mechanism 64.

[0090] At this time, the compression of the compression coil spring 70 causes a strong reaction force to act on the holding mechanism 64. As a result, the frame 64a of the holding mechanism 64 deforms slightly to conform to the surface 21a of the pressing member 21. In addition, because the pressing member 21 is pressed by the holding mechanism 64, the pressing member 21 and the porous plate 22 are pressed against each other.

[0091] Next, the fluid supply source 28 is activated and the valve 24b is opened (see Figure 9). This connects the fluid supply source 28 to the flow path 20c formed in the bottom wall 20a of the frame 20 of the chuck table 18, and supplies fluid (e.g., gas) to the underside of the porous plate 22. Most of this fluid then ejects from the outer periphery of the porous plate 22, that is, from the exposed portion not covered by the pressing member 21.

[0092] In the foreign matter removal method shown in Figure 7, the portion of the porous plate 22 inside the outer periphery is covered by the pressing member 21, and fluid is ejected from the outer periphery of the porous plate 22. That is, in this invention, most of the fluid supplied from the fluid supply source 28 passes through the outer periphery of the porous plate. Therefore, in this method, it is possible to effectively remove foreign matter that has accumulated on the outer periphery of the porous plate 22 of the chuck table 18.

[0093] It should be noted that the above description represents only one aspect of the present invention, and the present invention is not limited to what has been described above. For example, the foreign matter removal method of the present invention may be performed on a chuck table provided in a processing device other than a grinding device (for example, a cutting device).

[0094] Furthermore, the pressing member used in the present invention is not limited to a mirror wafer, but may be made of a flexible material such as resin. Alternatively, in the present invention, the holding mechanism 64 of the transport unit 62 may be used as the pressing member. That is, in the present invention, the ejection step (S2) may be performed with the porous plate 22 of the chuck table 18 in contact with the frame 64a and porous plate 64b of the holding mechanism 64.

[0095] Furthermore, the structures and methods of the embodiments described above can be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0096] 2: Grinding equipment 4: Base (4a: Recess) 6a, 6b: Cassette mounting area 8a, 8b: Cassette 10: Conveyor Unit 11: Workpiece (11a: front side, 11b: back side) 12:Position adjustment mechanism 13: Planned division line 14: Conveyor Unit 15: Devices 16: Turntable 18: Chuck Table 20: Frame (20a: bottom wall, 20b: side wall, 20c: flow path) 21: Pressing member (21a: front surface, 21b: back surface) 22: Porous plate 24a, 24b: Valve 26: Suction source 28: Fluid supply source 30:Support structure 32: Movement mechanism 34: Guide rail 36: Mobile Plate 38: Screw shaft 40: Motor 42: Grinding Unit 44: Spindle Housing 46: Spindle 48: Mount 50a, 50b: Grinding wheels 52: Wheel base 54: Grinding wheel 56a, 56b: Grinding fluid supply unit 58a, 58b: Nozzle 60: Motor 62: Conveyor Unit 64: Holding mechanism (64a: frame body, 64b: porous plate) 66: Bolt 68: Support member 70: Compression coil spring 72: Arm 74: Support shaft 76: Motor 78: Moving mechanism (78a: Moving plate, 78b: Nut) (78c: screw shaft, 78d: motor) 80: Washing device

Claims

[Claim 1] A method for removing foreign matter stuck on the outer periphery of a porous plate of a chuck table, comprising: a frame having a bottom wall and side walls erected from the outer periphery of the bottom wall, wherein a flow path capable of selectively communicating with a suction source or a fluid supply source is formed in the bottom wall; and a porous plate fixed in a recess defined by the bottom wall and the side walls, wherein the flow path is connected to the suction source to suction and hold a workpiece placed on the porous plate, the method for removing foreign matter stuck on the outer periphery of the porous plate of a chuck table, The arrangement step involves positioning the pressing member on the porous plate such that the portion of the porous plate inside the outer periphery is covered, and the outer periphery of the porous plate is exposed. The device includes a discharge step in which, while the porous plate and the pressing member are pressed against each other, the flow path and the fluid supply source are connected to discharge fluid from the outer periphery of the porous plate, A method for removing foreign matter, the pressing member comprising a wafer and / or resin.

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