Clogging detection method

Abstract

To provide a clogging determination method specialized for determining a state of clogging in an outer peripheral portion of a porous plate of a chuck table.SOLUTION: A value of pressure in a channel is measured while a suction source is operated in a state where a shielding member is arranged on a porous plate communicating with the suction source via the channel so that an inner part than an outer peripheral portion of the porous plate is covered and the outer peripheral portion of the porous plate is exposed. The value of the pressure in the channel is measured while the suction source is operated in a state where leakage from the inner part than the outer peripheral portion of the porous plate is prevented. Here, when the outer peripheral portion of the porous plate is clogged, leakage through the outer peripheral portion is less likely to occur, so that the measured value of the pressure becomes smaller. Therefore, when the measured value of the pressure is less than a preset threshold value, it can be determined that the outer peripheral portion of the porous plate is clogged.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a clogging determination method for determining a clogged state at an outer peripheral portion of a porous plate of a chuck table including a frame body having a bottom wall and side walls erected from an outer peripheral portion of the bottom wall, and a flow path communicable with a suction source formed in the bottom wall, and a porous plate fixed in a recess defined by the bottom wall and the side walls.

Background Art

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

[0003] First, photolithography or the like is performed to form a plurality of devices each including a large number of elements on the surface of a workpiece such as a wafer. Next, the back surface 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, by operating the suction source with the workpiece placed on the porous plate, the workpiece is sucked and held by the chuck table.

[0006] Furthermore, when a workpiece is processed in a processing device, friction between the processing tool and the workpiece causes the workpiece to heat up, and scraps (processing waste) are generated from the removed workpiece. When the workpiece heats up and / or the processing waste adheres 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, a liquid such as pure water (processing fluid) is often supplied to the contact interface (processing point) between the processing tool and the workpiece in order to cool the workpiece and wash away processing debris, while the workpiece is being processed.

[0008] In this process, the workpiece is held in place 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, potentially clogging the porous plate. When foreign matter clogs the porous plate, the suction force acting on the workpiece may weaken.

[0009] Therefore, in such processing apparatus, the state of clogging in the porous plate is determined (see, for example, Patent Document 1), and if it is determined that foreign matter is lodged in the porous plate, a process to remove the foreign matter may be performed (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2018-114563 [Patent Document 2] Japanese Patent Publication No. 2015-36173 [Overview of the project] [Problems that the invention aims to solve]

[0011] The determination of the clogging state in the porous plate described above is performed using images formed by imaging the surface of the porous plate while air and water are ejected from it. In other words, this determination is performed on the entire surface of the porous plate.

[0012] However, 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. Even if the center of the porous plate is not clogged with foreign matter, if the outer periphery is clogged, it may become difficult for the chuck table to hold the workpiece.

[0013] In view of this, the object of the present invention is to provide a clogging determination method specifically for determining the state of clogging on the outer periphery of a porous plate of a chuck table. [Means for solving the problem]

[0014] According to the present invention, a clogging determination method is provided for determining the state of clogging on the outer periphery of a porous plate in a chuck table, the chuck table comprising a frame having a bottom wall and side walls erected from the outer periphery of the bottom wall, with a flow path formed in the bottom wall that can communicate with a suction source, and a porous plate fixed in a recess defined by the bottom wall and the side walls, the method comprising: an arrangement step of arranging a shielding 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; a measurement step after the arrangement step of measuring the pressure value in the flow path while operating the suction source with the flow path and the suction source in communication; and a determination step of determining that the outer periphery of the porous plate is clogging if the pressure value measured in the measurement step is below a preset threshold. [Effects of the Invention]

[0015] In the present invention, while operating the suction source, the pressure value in the flow path is measured in a state where a shielding member is disposed on the porous plate such that a portion inside the outer peripheral portion of the porous plate communicating with the suction source through the flow path is covered and the outer peripheral portion of the porous plate is exposed. That is, in the present invention, the pressure value in the flow path is measured while operating the suction source in a state where leakage from a portion inside the outer peripheral portion of the porous plate is prevented.

[0016] Here, when the outer peripheral portion of the porous plate is clogged, leakage through this outer peripheral portion is less likely to occur, so the measured pressure value becomes small. Therefore, when the measured pressure value is below a preset threshold value, it can be determined that the outer peripheral portion of the porous plate is clogged.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a perspective view schematically showing an example of a grinding apparatus. [Figure 2] FIG. 2 is a perspective view schematically 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 a tip portion 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 driving method of a grinding apparatus including a clogging determination method. [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 a measurement step [Figure 10] FIG. 10 is a diagram schematically showing a state of an ejection step. [Figure 11] FIG. 11 is a flowchart schematically showing another example of a driving method of a grinding apparatus including a clogging determination method. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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. In FIG. 1, some components of the grinding apparatus are shown as functional blocks. The X-axis direction (left-right direction) and the 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 the Y-axis direction.

[0019] 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 mounting regions 6a and 6b are provided. And on each of the cassette mounting regions 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 mounted.

[0020] That is, each of the cassettes 8a and 8b is provided with a plurality of accommodation regions in which workpieces can be accommodated. FIG. 2 is a perspective view schematically showing an example of a workpiece accommodated in the cassettes 8a and 8b. The workpiece 11 shown in FIG. 2 is, for example, a wafer made of a semiconductor material such as silicon (Si) and having a circular front surface 11a and a back surface 11b.

[0021] The workpiece 11 is partitioned into a plurality of regions by a plurality of division planned lines 13 set in a lattice shape, and devices 15 such as ICs are formed on the front surface 11a side of each region. The workpiece 11 may also 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.

[0022] Furthermore, this tape protects the device 15 by mitigating the impact applied to the surface 11a side when grinding the back surface 11b side of the workpiece 11. There are no restrictions on the material, shape, structure, and size of the workpiece 11. For example, the workpiece 11 may include other semiconductor materials, ceramics, resins, or metals.

[0023] Furthermore, as shown in Figure 1, a recess 4a is formed behind the cassette placement areas 6a and 6b, and a transport unit 10 is provided inside this recess 4a. This transport unit 10 is used to transport the workpiece 11 before grinding from one of the multiple storage areas (original storage area) of the cassettes 8a and 8b, and to transport the workpiece 11 after grinding back into the original storage area, for example.

[0024] Specifically, the transport unit 10 has, for example, multiple joints and a robot hand, and holds the workpiece 11 on one side of this robot hand. Furthermore, the transport unit 10 can also reverse the robot hand that holds the workpiece 11, that is, it can reverse the top and bottom of the workpiece 11.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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).

[0033] 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.

[0034] 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.

[0035] The outer diameter of the frame 20 is slightly larger than the diameter of the workpiece 11, and its inner diameter (the diameter of the porous plate 22) is slightly smaller than the diameter of the workpiece 11. Furthermore, the upper surface of the side wall 20b of the frame 20 and the upper surface of the porous plate 22 are configured to have a shape corresponding to the side surface of a cone, and function as holding surfaces for holding the workpiece 11.

[0036] Furthermore, a flow path 20c is formed in the bottom wall 20a, opening at the bottom surface of the recess and penetrating the bottom wall 20a. This flow path 20c is connected to the suction source 26a via valve 24a and to the air supply source 26b via valve 24b. A pressure gauge 28 is also provided in the flow path 20c to measure the pressure value in the flow path 20c.

[0037] The suction source 26a includes, for example, an ejector. The air supply source 26b includes, for example, a tank for storing high-pressure air, a filter for removing foreign matter mixed in the gas supplied from the tank, and a regulator for adjusting the pressure of the gas supplied from the tank.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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).

[0042] 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.

[0043] 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.

[0044] Next, the suction source 26a 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Furthermore, a grinding unit 42 is provided on the front (surface) of the movable plate 36. This grinding unit 42 has 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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 54. As a result, the back surface 11b (top surface) of the workpiece 11 is roughly or finish-ground while the grinding fluid L is supplied to the contact interface (machining point) between the workpiece 11 and the multiple grinding wheels 54.

[0060] 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 holding the workpiece 11 is positioned at the loading / unloading position A.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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 via piping (not shown) and a valve (not shown) to a suction source (not shown) having a structure similar to that of the suction source 26a or an air supply source (not shown) having a structure similar to that of the air supply source 26b.

[0065] 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.

[0066] 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.

[0067] 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 width of the bolt 66 head is greater than the diameter of the through hole. Therefore, the bolt 66 will not fall through the through hole.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] First, the operation of the suction source 26a is stopped, and the valve 24a is closed. Next, the air supply source 26b 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] Furthermore, a cover (not shown) is provided on the upper surface of the base 4 to cover the aforementioned components. A touch panel 82 is positioned on the front of this cover. This touch panel 82 is composed of, for example, an input unit such as a capacitive or resistive touch sensor and a display unit such as a liquid crystal display or an organic EL (Electro-Luminescence) display, and functions as a user interface.

[0084] The components of the grinding apparatus 2 described above are controlled by a control unit 84 built into the grinding apparatus 2. This control unit 84 includes a processing unit 84a and a storage device 84b. The processing unit 84a is composed of a processor, such as a CPU (Central Processing Unit).

[0085] Furthermore, the storage device 84b is composed of, for example, volatile memory such as DRAM (Dynamic Random Access Memory) or SRAM (Static Random Access Memory) and non-volatile memory such as SSD (Solid State Drive) (NAND flash memory) or HDD (Hard Disk Drive) (magnetic storage device).

[0086] The memory device 84b stores various types of information (data, programs, etc.) used in the processing unit 84a. For example, the memory device 68b stores a pressure threshold used to determine the state of clogging at the outer periphery of the porous plate 22 of the chuck table 18. An example of this determination will be described later.

[0087] Furthermore, the processing unit 84a controls the components of the grinding device 2 to read and execute the program stored in the storage device 84b, for example. For example, the processing unit 84a controls the components of the grinding device 2 to read and execute a program from the storage device 84b for rough grinding or finish grinding the back surface 11b of the workpiece 11.

[0088] In the grinding apparatus 2, rough grinding or finish grinding is performed on the back (top) 11b side of the workpiece 11 with the suction source 26a 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.

[0089] Figure 7 is a schematic flowchart illustrating an example of a driving method for the grinding device 2, which includes a clogging determination method for determining the state of clogging on the outer periphery of the porous plate 22 of the chuck table 18. In short, this method is an example of a driving method for the grinding device 2 to remove foreign matter stuck on the outer periphery when it is determined that the outer periphery of the porous plate 22 is clogged.

[0090] Specifically, in this method, first, the shielding member is placed on the porous plate 22 (placement step S1). Figure 8 is a schematic diagram showing the arrangement step S1. The shielding member 21 placed on the porous plate 22 is, for example, a wafer having a circular surface 21a and a back surface 21b, and made of a semiconductor material such as silicon (Si).

[0091] The diameter of the shielding member 21 is smaller than the diameter of the workpiece 11 and the diameter of the porous plate 22. For example, if the diameter of the workpiece 11 is 8 inches, the diameter of the shielding member 21 is 6 inches. The shielding member 21 is a wafer on which the device 15 shown in Figure 2 is not formed, a so-called mirror wafer.

[0092] Furthermore, the shielding member 21 may 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.

[0093] The shielding member 21 is positioned on the porous plate 22, for example, by manually placing it so that the center of the shielding member 21 aligns with the center of the porous plate 22. Alternatively, the shielding member 21 may be housed in the cassettes 8a and 8b shown in Figure 1 and placed on the porous plate 22 using the transport units 10 and 14 described above.

[0094] When the shielding 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 placement step S1, the operation of both the suction source 26a and the air supply source 26b is stopped, and the valves 24a and 24b are closed.

[0095] Next, with the flow path 20c formed in the bottom wall 20a of the frame 20 connected to the suction source 26a, the pressure value in the flow path 20c is measured while the suction source 26a is operated (measurement step S2). Figure 9 is a schematic diagram showing the measurement step S2.

[0096] Specifically, in measurement step S2, the suction source 26a is activated and the valve 24a is opened, and then the pressure value in the flow path 20c is measured by the pressure gauge 28. The pressure value in the flow path 20c measured by the pressure gauge 28 may be displayed on the display unit of the touch panel 82.

[0097] Next, it is determined whether the pressure value measured in measurement step S2 is below a preset threshold (determination step S3). Specifically, in determination step S3, the processing unit 84a compares the pressure value measured in measurement step S2 with the threshold stored in the storage device 84b.

[0098] This threshold is, for example, a predetermined value within the range of 65kPa to 75kPa. Alternatively, this threshold may be a value obtained by subtracting a predetermined value within the range of 2kPa to 8kPa from the pressure value measured by performing measurement step S2 with the shielding member 21 placed on the porous plate 22 of a new chuck table 18, that is, a porous plate 22 whose outer periphery is not clogged.

[0099] Then, if the pressure value measured in measurement step S2 is below a preset threshold (determination step S3: YES), the processing device 84a determines that the outer periphery of the porous plate 22 is clogged.

[0100] Furthermore, if it is determined that the outer periphery of the porous plate 22 is clogged, air is ejected from the outer periphery of the porous plate 22 while the porous plate 22 and the shielding member 21 are pressed against each other (ejection step S4). Figure 10 is a schematic diagram showing the ejection step S4. This ejection step S4 is carried out, for example, in the following order.

[0101] First, the turntable 16 is rotated so that the chuck table 18, which includes the porous plate 22 on which the shielding member 21 is placed, is positioned at the loading / unloading position A. Note that if the shielding member 21 is placed on the porous plate 22 while the chuck table 18 is positioned at the loading / unloading position A, it is not necessary to rotate the turntable 16.

[0102] Next, the motor 76 is operated to rotate the holding mechanism 64 so that it is positioned directly above the shielding member 21. Then, the motor 78d of the moving mechanism 78 is operated to lower the holding mechanism 64 so that the shielding member 21 is pressed against by the porous plate 64b of the holding mechanism 64.

[0103] 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 shielding member 21. In addition, because the shielding member 21 is pressed by the holding mechanism 64, the porous plate 22 and the shielding member 21 are pressed against each other.

[0104] Next, the operation of the suction source 26a is stopped and the valve 24a is opened, while the air supply source 26b is activated and the valve 24b is opened. As a result, the flow path 20c formed in the bottom wall 20a of the frame 20 of the chuck table 18 and the air supply source 26b are connected, and air is supplied to the underside of the porous plate 22.

[0105] This air is then ejected from the outer periphery of the porous plate 22, that is, from the portion exposed and not covered by the shielding member 21. As a result, in ejection step S4, at least a portion of the foreign matter stuck on the outer periphery of the porous plate 22 of the chuck table 18 can be blown away and removed by the air.

[0106] Figure 11 is a schematic flowchart illustrating another example of a driving method for the grinding apparatus 2, which includes a clogging determination method for determining the state of clogging on the outer periphery of the porous plate 22 of the chuck table 18. In short, this method is an example of a driving method for the grinding apparatus 2 that prompts the operator to replace the chuck table 18 if foreign matter clogged on the outer periphery of the porous plate 22 cannot be sufficiently removed in the ejection step S4.

[0107] In this method, the above-described placement step S1, ejection step S4, measurement step S2, and determination step S3 are performed in order. If it is determined in determination step S3 that the outer periphery of the porous plate 22 is clogged, the operator is notified that the chuck table 18 needs to be replaced (notification step S5).

[0108] Specifically, in notification step S5, information indicating that the chuck table 18 needs to be replaced is displayed on the display unit of the touch panel 82. This prompts the operator to replace the chuck table 18, including the porous plate 22, which has so much grinding debris stuck to its outer circumference that it cannot be removed in ejection step S4.

[0109] It should be noted that the present invention is not limited to the above-described content. For example, the clogging determination method of the present invention may be used to determine the state of clogging on the outer periphery of a porous plate of a chuck table included in a processing device other than a grinding device, such as a cutting device or a laser processing device.

[0110] 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]

[0111] 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: Shielding material (21a: front surface, 21b: back surface) 22: Porous plate 24a, 24b: Valve 26a: Suction source 26b: Air supply source 28: Pressure gauge 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 82: Touch panel 84: Control unit (84a: Processing unit, 84b: Memory device)

Claims

[Claim 1] A clogging determination method for determining the state of clogging 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, with a flow path formed in the bottom wall that can communicate with a suction source, and a porous plate fixed in a recess defined by the bottom wall and the side walls, wherein The arrangement step of placing the shielding 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, Following the arrangement step, a measurement step is performed in which the flow path and the suction source are connected and the suction source is operated while measuring the pressure value in the flow path, A determination step in which it is determined that the outer periphery of the porous plate is clogged if the pressure value measured in the measurement step falls below a preset threshold, A clogging detection method comprising the following features.

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