Checking plate and method for checking clogging of chuck table

Abstract

To provide a checking plate which can properly determine a degree of clogging on a suction surface of a chuck table to solve a problem that clogging progresses more than expected to prevent restoration of a suction surface and force the chuck table to be replaced with a new chuck table, resulting in uneconomical operation.SOLUTION: A checking plate 15 checks clogging of a chuck table 6 in a grinding device which is formed including: a suction surface 61 which suctions and holds a wafer; a chuck table 6 formed by a frame body 62 enclosing the suction surface 61; and grinding means which grinds the wafer held by the chuck table 6. The check plate 15 has a diameter which is slightly smaller than a diameter of the suction surface 61 of the chuck table 6.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a confirmation plate for checking clogging of a chuck table and a method for checking clogging of a chuck table using the confirmation plate. [Background technology]

[0002] Wafers have multiple devices such as ICs and LSIs formed on their surface, separated by planned dividing lines. The back side is ground using a grinding machine to form the wafer to a specified thickness, and then the wafer is divided into individual device chips using a cutting machine and laser processing machine. These chips are then used in electrical devices such as mobile phones and personal computers.

[0003] The grinding device includes a chuck table consisting of a suction surface that holds the wafer by suction and a frame that surrounds the suction surface, and grinding means that grinds the wafer held on the chuck table, and can finish the wafer to a desired thickness with high precision (see, for example, Patent Document 1).

[0004] Furthermore, the diameter of the suction surface of the chuck table is formed to correspond to the diameter of the wafer, and when a wafer held by suction on the chuck table is ground, processing water mixed with contaminants including grinding debris (hereinafter referred to as "contamination") is sucked into the suction surface from the outer periphery of the wafer, causing the outer periphery of the suction surface to become clogged with the contaminants, resulting in a decrease in suction force. Therefore, maintenance is performed periodically or at any time to grind the suction surface of the chuck table to remove the clogging and restore suction force. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-060481 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the progression of clogging on the suction surface of the chuck table differs depending on the user of the grinding device, and the criteria for determining clogging also differ. Therefore, if proper maintenance is not performed, clogging may progress more than expected, making it difficult to restore suction force, and the user may be forced to replace the chuck table with a new one, which is uneconomical.

[0007] The present invention has been made in view of the above-mentioned circumstances, and its main technical object is to provide a confirmation plate and a method for checking clogging of a chuck table that can appropriately determine clogging of the suction surface of the chuck table and can solve the problem that clogging progresses more than expected, making it impossible to restore suction force, and forcing the chuck table to be replaced with a new one, which is uneconomical. [Means for solving the problem]

[0008] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a confirmation plate for checking for clogging of a chuck table in a grinding apparatus configured to include a suction surface that suction-holds a wafer and a chuck table consisting of a frame that surrounds the suction surface, and grinding means that grinds the wafer held on the chuck table, the confirmation plate having a diameter slightly smaller than the diameter of the suction surface of the chuck table.

[0009] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a method for checking for clogging in a chuck table using the above-mentioned confirmation plate, comprising: a placing step of placing the confirmation plate on the suction surface of the chuck table; a suction and holding step of generating a suction force on the suction surface to hold the confirmation plate by suction; and a measuring step of measuring the pressure in the suction path of the chuck table, wherein, when the pressure in the suction path is reduced and the measured value becomes equal to or less than a predetermined value in the measuring step, a clogging determination step is provided for determining that clogging has occurred on the outer periphery of the suction surface of the chuck table.

[0010] Furthermore, in order to solve the above-mentioned main technical problem, according to the present invention, there is provided a method for checking for clogging of a chuck table using the above-mentioned confirmation plate, comprising: a placing step of placing the confirmation plate on a suction surface of the chuck table; a suction and holding step of generating suction force on the suction surface to hold the confirmation plate by suction; a water supply step of supplying water to the outer periphery of the confirmation plate; and a measurement step of measuring the pressure in a suction path of the chuck table, wherein the suction of the chuck table is stopped in the suction and holding step; the outer periphery of the confirmation plate is filled with water in the water supply step; and the measurement step measures the time from when the suction of the chuck table is activated and the pressure in the suction path of the chuck table drops until the supplied water is sucked out and the water disappears from the outer periphery of the confirmation plate and the pressure in the suction path rises; and if the measured time exceeds a predetermined time, it is determined that clogging has occurred on the outer periphery of the suction surface.

[0011] It is preferable that the clogging determination step be performed periodically. Furthermore, if it is determined in the clogging determination step that clogging has occurred on the suction surface of the chuck table, it is preferable that a grinding step be included in which the suction surface of the chuck table is ground to remove the clogging and restore suction force. [Effects of the Invention]

[0012] The confirmation plate of the present invention is a confirmation plate for checking for clogging of the chuck table in a grinding device configured to include a chuck table consisting of a suction surface that suction-holds a wafer and a frame that surrounds the suction surface, and grinding means that grinds the wafer held on the chuck table.Since the confirmation plate has a diameter slightly smaller than the diameter of the suction surface of the chuck table, it becomes possible for the user of the grinding device to quantitatively determine clogging, and as clogging progresses it becomes difficult to restore suction force through maintenance, eliminating the problem that replacement with a new chuck table is necessary, which is uneconomical.

[0013] Furthermore, the method of checking for clogging in a chuck table of the present invention comprises a placing step of placing the confirmation plate on the suction surface of the chuck table, a suction and holding step of generating suction force on the suction surface to suck and hold the confirmation plate, and a measuring step of measuring the pressure in the suction path of the chuck table, and includes a clogging determination step of determining that clogging has occurred on the outer periphery of the suction surface of the chuck table when the pressure in the suction path is reduced and the measured value falls below a predetermined value.This allows users of the grinding machine to quantitatively determine clogging, and solves the problem that as clogging progresses, it becomes difficult to restore suction force through maintenance, necessitating the uneconomical replacement of the chuck table with a new one.

[0014] Furthermore, the method for checking for clogging of a chuck table of the present invention comprises a placing step of placing the confirmation plate on the suction surface of the chuck table, a suction and holding step of generating suction force on the suction surface to hold the confirmation plate by suction, a water supply step of supplying water to the outer periphery of the confirmation plate, and a measurement step of measuring the pressure in the suction path of the chuck table, wherein the suction of the chuck table is stopped in the suction and holding step, the outer periphery of the confirmation plate is filled with water in the water supply step, and the measurement step measures the time from when the suction of the chuck table is activated and the pressure in the suction path of the chuck table drops to when the supplied water is sucked in and the water disappears from the outer periphery of the confirmation plate and the pressure in the suction path rises, and if the measured time exceeds a predetermined time, it is determined that clogging has occurred on the outer periphery of the suction surface.This solves the problem that as clogging progresses, it becomes difficult to restore suction force through maintenance, necessitating the uneconomical replacement of the chuck table with a new one. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is an overall perspective view of the grinding device. [Figure 2]2 is a conceptual diagram showing a suction source and a suction path connected to a chuck table disposed in the grinding apparatus shown in FIG. 1. [Figure 3] 1 is a perspective view of an embodiment of a confirmation plate constructed in accordance with the present invention; [Figure 4] FIG. 10 is a perspective view showing an example of a placing step of the present embodiment. [Figure 5] FIG. 1A is a conceptual diagram showing an embodiment of the suction and holding step of the present embodiment, and FIG. 1B is a conceptual diagram showing a change in pressure in the suction path when the suction and holding step shown in FIG. 1A is carried out. [Figure 6] FIG. 10 is a perspective view showing an embodiment of the water supplying step of this embodiment. [Figure 7] FIG. 10 is a conceptual diagram showing a change in pressure in the suction path when a measurement step is performed after a water supply step is performed. [Figure 8] 1 is a perspective view showing an embodiment of a grinding process. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a confirmation plate and a method for checking clogging of a chuck table configured according to the present invention will be described in detail with reference to the accompanying drawings.

[0017] FIG. 1 shows a grinding apparatus 1 suitable for the confirmation plate and the method for checking clogging of the chuck table according to this embodiment, which will be described later. The grinding apparatus 1 includes a chuck table 6 that holds a wafer W by suction and grinding means 3 and 4 that grind the wafer W held on the chuck table. The chuck table 6 includes a suction surface 61 that holds the wafer W, which is the workpiece, by suction and a frame 62 that surrounds the suction surface 61. Note that the illustrated grinding apparatus 1 includes three chuck tables 6, a rough grinding means 3 that roughly grinds the backside of the wafer W, and a finish grinding means 4 that finish grinds the backside of the wafer W that has been roughly ground by the rough grinding means 3. However, the grinding apparatus to which the confirmation plate and the method for checking clogging of the chuck table according to this embodiment can be applied is not limited to the grinding apparatus 1 shown in FIG. 1 and may be, for example, a grinding apparatus equipped with only one chuck table.

[0018] The grinding machine 1 shown in Fig. 1 includes a roughly rectangular parallelepiped housing 2. In Fig. 1, a support wall 21 is erected on the rear end side of the housing 2. Two pairs of guide rails 22, 22 and 23, 23 extending in the vertical direction (Z-axis direction) are provided on the inner surface of the support wall 21. A rough grinding unit 3 as rough grinding means is mounted on one of the guide rails 22, 22 so as to be movable in the vertical direction, and a finish grinding unit 4 as finish grinding means is mounted on the other guide rails 23, 23 so as to be movable in the vertical direction.

[0019] The rough grinding unit 3 comprises a unit housing 31, a wheel mount 33 arranged at the lower end of a rotating shaft 32 supported rotatably on the unit housing 31, a rough grinding wheel 34 attached to the wheel mount 33 and having a plurality of grinding stones 35 arranged in a ring shape on its underside, an electric motor 36 attached to the upper end of the unit housing 31 and rotating the wheel mount 33 in the direction indicated by arrow R1, and a movable base 38 supporting the unit housing 31 via a support member 37.

[0020] The movable base 38 is provided with guided grooves that slidably engage with the guide rails 22, 22 provided on the support wall 21. The illustrated grinding apparatus 1 is equipped with a grinding feed mechanism 39 that is provided as an elevating means for raising and lowering the movable base 38 of the rough grinding unit 3 along the guide rails 22, 22. The grinding feed mechanism 39 is equipped with a pulse motor 391, an externally threaded rod 392 that is disposed in the vertical direction on the support wall 21 parallel to the guide rails 22, 22 and is driven to rotate by the pulse motor 391, and an internally threaded block (not shown) that is attached to the movable base 38 and threadedly engages with the externally threaded rod 392, and the rough grinding unit 3 is moved up and down by driving the externally threaded rod 392 in forward and reverse directions by the pulse motor 391.

[0021] The finish grinding unit 4 is configured in substantially the same manner as the rough grinding unit 3, and includes a unit housing 41, a wheel mount 43 disposed at the lower end of a rotating shaft 42 rotatably supported on the unit housing 41, a finish grinding wheel 44 attached to the wheel mount 43 and having a plurality of grinding stones 45 arranged in a ring shape on its underside, an electric motor 46 attached to the upper end of the unit housing 41 for rotating the wheel mount 43 in the direction indicated by arrow R2, and a movable base 48 supporting the unit housing 41 via a support member 47.

[0022] The movable base 48 is provided with guided grooves that slidably engage with the guide rails 23, 23 provided on the support wall 21. The grinding apparatus 1 in the illustrated embodiment is equipped with a grinding feed mechanism 49 that is provided as an elevating means for raising and lowering the movable base 48 of the finish grinding unit 4 along the guide rails 23, 23. The grinding feed mechanism 49 is equipped with a pulse motor 491, an externally threaded rod 492 that is disposed in the vertical direction on the support wall 21 parallel to the guide rails 23, 23 and is rotated by the pulse motor 491, and an internally threaded block (not shown) that is attached to the movable base 48 and threadedly engages with the externally threaded rod 492, and the externally threaded rod 492 is driven to rotate forward and backward by the pulse motor 491, thereby moving the finish grinding unit 4 in the vertical direction.

[0023] A water supply source (not shown) for supplying grinding water is connected to the rotating shafts 32 and 42, which are rotated by the electric motors 36 and 46, and grinding water is supplied via the rotating shafts 32 and 42 to the grinding area between the grinding wheel 35 and the grinding wheel 45 and the wafer W held on the chuck table 6.

[0024] The grinding device 1 includes a turntable 5 disposed in front of the support wall 21 so as to be substantially flush with the upper surface of the device housing 2. The turntable 5 is formed in the shape of a relatively large disk, and is rotated appropriately in the direction indicated by arrow R3 by a rotation drive mechanism (not shown) within a drain pan 20 on the upper surface of the device housing 2. Three of the chuck tables 6 are disposed on the turntable 5, each at an angle of 120 degrees. Each chuck table 6 is equipped with a rotation drive means (not shown) and is configured to be rotatable in the direction indicated by arrow R4. The chuck table 6 includes a suction surface 61 formed of a breathable member and forming the holding surface of the chuck table 6, and a frame 62 surrounding the suction surface 61.

[0025] The three chuck tables 6 arranged on the turntable 5 are moved sequentially from the workpiece carry-in / out area A → the rough grinding area B → the finish grinding area C → the workpiece carry-in / out area A by rotating the turntable 5 in the direction indicated by the arrow R3. A cleaning water supply nozzle 17 is arranged near the workpiece carry-in / out area A in the drain pan 20, for supplying cleaning water (which can also be used as the grinding water supplied from the water supply source) to the upper surface of the suction chuck 62 of the chuck table 6 positioned in the workpiece carry-in / out area A.

[0026] The illustrated grinding apparatus 1 includes a first cassette 7 disposed on one side of the workpiece carry-in / out area A and accommodating a plurality of wafers W, which are workpieces before grinding; a second cassette 8 disposed on the other side of the workpiece carry-in / out area A and accommodating a plurality of wafers W after grinding; a temporary placement table 9 disposed between the first cassette 7 and the workpiece carry-in / out area A and for centering the wafers W; cleaning means 11 disposed between the workpiece carry-in / out area A and the second cassette 8; The workpiece carrying-in / out means 12 carries out the wafer W stored therein to the temporary placement table 9 and carries the wafer W cleaned by the cleaning means 11 into the second cassette 8, a first transport means 13 transports the wafer W held on the temporary placement table 9 onto the chuck table 6 positioned in the workpiece carrying-in / out area A, and a second transport means 14 transports the wafer W after grinding placed on the chuck table 6 positioned in the workpiece carrying-in / out area A to the cleaning means 11.

[0027] In the grinding machine 1 of this embodiment, a confirmation plate storage cassette 16 for storing a confirmation plate 15 (described later) is disposed on the machine housing 2 adjacent to the second cassette 8. The confirmation plate 15 stored in the confirmation plate storage cassette 16 can be removed by the workpiece carry-in / out means 12 and transported to the temporary placement table 9, and the confirmation plate 15 that has been transported to the cleaning means 11, cleaned, and dried can be transported to and stored in the confirmation plate storage cassette 16 by the workpiece carry-in / out means 12. The position of the confirmation plate storage cassette 16 is not limited to the position shown in the figure, and may be located anywhere as long as it can be removed by the workpiece carry-in / out means 12 and transported to the temporary placement table 9.

[0028] The grinding apparatus 1 is not limited to the configuration including the first transport means 13 and the second transport means 14 described above, and may be provided with one transport means serving as both the first transport means 13 and the second transport means 14. The one transport means may transport the unprocessed wafer W from the temporary storage table 9 to the chuck table 6 positioned in the workpiece carry-in / out area A, and transport the ground wafer W from the chuck table 6 positioned in the workpiece carry-in / out area A to the cleaning means 11.

[0029] A control means 100 including an operation panel for issuing grinding instructions and specifying processing conditions is disposed on the front side of the apparatus housing 2, where the workpiece carry-in / out means 12 is disposed. The control means 100 includes a central processing unit (CPU) that performs calculations according to a control program, a read-only memory (ROM) that stores the control program and the like, a readable / writable random access memory (RAM) that serves as storage means for storing calculation results and the like, an input interface, and an output interface (all of which are not shown). The control means 100 configured in this manner controls the various operating parts of the grinding apparatus 1 and also implements a method of checking for chuck table clogging of this embodiment, which checks for clogging in the chuck table 6 (described in detail later).

[0030] 2, a suction source 50 that generates a suction force on the suction surface 61 of the chuck table 6 is connected to the frame 62 of the chuck table 6 via a suction path 51. An on-off valve 52 is provided in the suction path 51, and a pressure sensor 110 that detects the pressure in the suction path 51 is also provided. The opening and closing of the on-off valve 52 is controlled by a control means 100, and the pressure measurement value detected by the pressure sensor 110 is transmitted to and stored in the control means 100. Note that, instead of providing the on-off valve 52, the generation of the suction force on the suction surface 61 may be controlled by controlling the operation of the suction source 50.

[0031] The confirmation plate 15 of this embodiment has a diameter slightly smaller than the diameter S1 (see FIG. 2) of the suction surface 61 of the chuck table 6 described above, and FIG. 3 shows the confirmation plate 15 configured based on the present invention.

[0032] 3, the confirmation plate 15 is a circular plate having a diameter S2 that is slightly smaller than the diameter S1 of the suction surface 61 of the chuck table 6 that suction-holds the wafer W accommodated in the first cassette 7. Here, "the diameter S2 that is slightly smaller than the diameter S1 of the suction surface 61 of the chuck table 6" means a diameter that is set so that, when the confirmation plate 15 is placed in the center of the suction surface 61 of the chuck table 6, only the outer peripheral region of the suction surface 61 of the chuck table 6 where clogging is expected to occur and where it is necessary to detect clogging early is exposed between the outer periphery 15a of the confirmation plate 15 and the outer periphery 61a of the suction surface 61 of the chuck table 6. If the diameter S2 of the confirmation plate 15 were significantly smaller than the diameter S1 of the suction surface 61, even when the confirmation plate 15 was placed on the suction surface 61, a central region where clogging rarely occurs would be exposed, making it difficult to properly determine clogging on the suction surface 61 of the chuck table 6 even when using the clogging checking method described below. For this reason, the confirmation plate 15 constructed according to the present invention is set to have a diameter S2 that is slightly smaller than the diameter S1 of the suction surface 61 of the chuck table 6. The diameter S2 of the confirmation plate 15 is set so that, when the confirmation plate 15 is placed in the center of the suction surface 61 of the chuck table 6, the outer periphery 15a of the confirmation plate 15 is preferably positioned within a range 10 mm inward from the outer periphery 61a of the suction surface 61, and more preferably within a range 5 mm inward from the outer periphery 61a of the suction surface 61.

[0033] The following describes a method for checking for clogging in the chuck table using the above-described check plate 15. First, a first embodiment of the method for checking for clogging in the chuck table constructed according to the present invention will be described.

[0034] (Placement process) Once the confirmation plate 15 is prepared, a placing step is carried out in which the confirmation plate 15 is placed on the suction surface 61 of the chuck table 6 of the grinding device 1.

[0035] The confirmation plate 15 of this embodiment is accommodated in the confirmation plate accommodating cassette 16 as described above. For example, every time grinding is performed on all wafers W accommodated in the first cassette 7, the confirmation plate 15 is carried out of the confirmation plate accommodating cassette 16 by the workpiece carry-in / out means 12 and placed on the temporary placement table 9 for centering. Next, the first transport means 13 is operated to transport the confirmation plate 15 to the chuck table 6 positioned in the workpiece carry-in / out area A, as shown in FIG. 4, and placed at the center of the suction surface 61. When the confirmation plate 15 is placed on the suction surface 61, a gap of, for example, about 5 mm is formed between the outer periphery 15a of the confirmation plate 15 and the outer periphery 61a of the suction surface 61, as shown in FIG. 5(a), and the outer periphery region Q of the suction surface 61 is exposed in an annular shape.

[0036] (Suction holding process) As described above, once the confirmation plate 15 is placed on the suction surface 61 of the chuck table 6, the on-off valve 52 arranged in the suction path 51 shown in FIG. 5(a) is opened, the suction source 50 reduces the pressure in the suction path 51, and the suction force V1 is generated on the suction surface 61 of the chuck table 6 to suck in the confirmation plate 15.

[0037] (Measurement process) As described above, at the same time as the suction holding process is started, the pressure sensor 110 starts measuring the pressure in the suction path 51 of the chuck table 6. The pressure measurement value measured by the pressure sensor 110 is transmitted to the control means 100 and stored in an appropriate memory as time passes from the start of measurement.

[0038] (Clogging determination process) 5(b) shows the change in pressure in the suction path 51 from the time (T0) when pressure measurement began during the above-described suction holding process. If no clogging occurs in the outer peripheral region Q of the suction surface 61 of the chuck table 6, the pressure measured by the pressure sensor 110 will gradually decrease, as shown by L1 in FIG. 5(b), but will not be significantly reduced, and will stabilize at a pressure below P1, the reference value for determining clogging, after a predetermined time (e.g., T1) has elapsed. In this case, the control means 100 will determine that no clogging occurs in the outer peripheral region Q of the suction surface 61 of the chuck table 6. In contrast, if contaminant-containing processing water is sucked into the suction surface 61 from the outer periphery of the wafer W during grinding by the grinding apparatus 1, causing clogging in the outer periphery region Q of the suction surface 61, the pressure in the suction path 51 drops significantly in the measurement process described above, and after a predetermined time (e.g., T1) has elapsed, the measured pressure drops below P1, which is the clogging judgment reference value, and remains stable at that low pressure, as shown by L2 in Fig. 5(b). The pressure value P1, which is the judgment reference value, is, for example, 0.8 atmospheres, and is determined in advance by experiments or the like.

[0039] As described above, if the measured pressure in the suction path 51 falls below the clogging judgment reference value P1, the control means 100 determines that clogging has occurred in the outer peripheral region Q of the suction surface 61 of the chuck table 6. The results of the clogging judgment process based on the first embodiment are notified to the operator by an appropriate method. If no clogging has occurred on the suction surface 61 of the chuck table 6, the operator is notified by displaying a message to that effect on a display means (not shown). If clogging has occurred on the suction surface 61, the operator is notified by, for example, displaying a warning that the chuck table 6 is clogged on a display means (monitor) (not shown), or by using an alarm lamp or alarm sound. Once the clogging judgment process is complete, the confirmation plate 15 is transported from the chuck table 6 by the second transport means 14 to the cleaning means 11, where it is cleaned and dried, and then stored in the confirmation plate storage cassette 16 by the workpiece transport means 12. As described above, when it is determined in the clogging determination step that there is clogging, it is preferable to carry out a grinding step (described later) to restore the suction force of the suction surface 61 of the chuck table 6. Then, it is preferable to prohibit grinding of the wafer W by the grinding device 1 until the clogging state is resolved.

[0040] When the grinding apparatus 1 shown in FIG. 1 is equipped with three chuck tables 6, it is preferable to perform the above-described suction holding process, measurement process, and clogging determination process for each of the three chuck tables 6. However, it is also possible to perform the above-described suction holding process, measurement process, and clogging determination process for only one chuck table 6, and use the determination results obtained there to determine the clogging state of the other two chuck tables 6.

[0041] The method for checking for clogging in a chuck table configured based on the present invention is not limited to the above-described embodiment 1. Hereinafter, another method for checking for clogging in a chuck table configured based on the present invention (embodiment 2) will be described.

[0042] (Placement process) The placement process performed in this embodiment 2 is similar to the placement process in the above-described embodiment 1, and involves placing the confirmation plate 15 stored in the confirmation plate storage cassette 16 via the temporary placement table 9 at the center of the suction surface 61 of the chuck table 6 positioned in the workpiece loading / unloading area A, as shown in FIG.

[0043] (Suction holding process) Next, as in the above-described first embodiment, the confirmation plate 15 is placed in the center of the suction surface 61 of the chuck table 6, and then the on-off valve 52 shown in FIG. 5(a) is opened, and the suction source 50 reduces the pressure in the suction path 51, generating a suction force V1 on the above-described suction surface 61 of the chuck table 6, thereby suction-holding the confirmation plate 15.

[0044] (Water supply process) After the suction holding step is performed as described above, the on-off valve 52 on the suction path 51 is closed or the suction source 50 is stopped to temporarily stop the suction of the confirmation plate 15 by the suction surface 61 of the chuck table 6. Next, as shown in FIG. 6 , cleaning water (water L) is supplied from the cleaning water supply nozzle 17 disposed adjacent to the workpiece loading / unloading area A to the outer periphery of the confirmation plate 15 placed and held on the chuck table 6, so that the water L is retained in at least the outer periphery region Q formed by the outer periphery 15a of the confirmation plate 15 and the outer periphery 61a of the suction surface 61, and the outer periphery 15a side of the confirmation plate 15 is blocked by the water L. Note that when the cleaning water supply nozzle 17 supplies the water L toward the outer periphery region Q between the outer periphery 15a of the confirmation plate 15 and the outer periphery 61a of the suction surface 61, the chuck table 6 may be slowly rotated in the direction indicated by arrow R4. This allows the water L to be efficiently and evenly supplied to the outer periphery 15a of the confirmation plate 15. The method of supplying water L to the outer periphery 15a of the confirmation plate 15 is not limited to the method of supplying water using the cleaning water supply nozzle 17 described above, but may be supplied directly by an operator or by a separate water supply means for carrying out this water supply process.

[0045] (Measurement process) As described above, with the outer peripheral region Q between the outer periphery 15a of the confirmation plate 15 and the outer periphery 61a of the suction surface 61 blocked with water L, the on-off valve 52 of the suction path 51 is opened to generate a suction force V1 by the suction source 50 on the suction surface 61 of the chuck table 6, and at the same time, the pressure sensor 110 starts measuring the pressure in the suction path 51. The pressure measurement value measured by the pressure sensor 110 is transmitted to the control means 100 together with the elapsed time from the start of pressure measurement T0.

[0046] (Clogging determination process) As shown in FIG. 7 , the pressure in the suction path 51 measured by the pressure sensor 110 drops sharply from time T0, when the pressure begins to drop as the suction path 51 is suctioned, due to water L being stored in the outer peripheral region Q between the outer periphery 15a of the confirmation plate 15 and the outer periphery 61a of the suction surface 61. Then, when the suction of the water L stored in the outer peripheral region Q is completed, air begins to be sucked directly from the outer peripheral region Q, and the measured pressure in the suction path 51 begins to increase. If no clogging occurs in the outer peripheral region of the suction surface 61 of the chuck table 6, the suction of the water L stored in the outer peripheral region Q is completed quickly, and the rapid drop in pressure ends at a relatively early time T2, as indicated by L3 in FIG. 7 . Then, air begins to be sucked from the outer peripheral region Q, and the measured pressure in the suction path 51 begins to increase, as shown.

[0047] Here, the control means 100 determines whether the elapsed time from time T0 when the pressure in the suction path 51 starts to drop to time T2 when the measured pressure value starts to rise exceeds a predetermined time T4 (for example, 2 seconds). As can be seen from Fig. 7, if the pressure drop ends and the measured pressure value starts to rise before the predetermined time T4 is exceeded, the control means 100 determines that no clogging has occurred in the outer peripheral region Q of the suction surface 61 of the chuck table 6.

[0048] In contrast, in the grinding apparatus 1, when contaminant-containing processing water is sucked from the outer periphery of the wafer W held on the chuck table 6 into the suction surface 61 of the chuck table 6 and clogging occurs in the outer periphery region of the suction surface 61, the suction of the water L stored in the outer periphery region Q does not complete quickly, the pressure drops significantly, and it takes time for the measured pressure value to start to rise, exceeding the predetermined time T4, and finally starts to rise at time T3 in Fig. 7. In this way, when clogging occurs in the outer periphery region Q of the suction surface 61 of the chuck table 6, it takes time for the pressure drop to finish, and the pressure after the measured pressure value of the suction path 51 starts to rise remains at a lower value compared to the above-mentioned L3.

[0049] As shown by L4 in FIG. 7 , if the time T3 until the measured pressure value of the suction path 51 starts to increase exceeds a predetermined time T4 during the measurement process, the control means 100 determines that clogging has occurred in the outer peripheral region Q of the suction surface 61 of the chuck table 6. The results of the clogging determination process performed according to the second embodiment can be notified to the operator by an appropriate method. The notification method may be the same as that described in the first embodiment. If clogging is determined during the clogging determination process as described above, it is preferable to prohibit grinding of the wafer W by the grinding apparatus 1 until the clogging state is resolved. After the clogging determination process is completed, the confirmation plate 15 is transported from the chuck table 6 by the second transport means 14 to the cleaning means 11, where it is cleaned and dried, and then stored in the confirmation plate storage cassette 16 by the workpiece transport means 12.

[0050] The method for checking for clogging of the chuck table according to this embodiment is preferably performed periodically. For example, the above-described method for checking for clogging of the chuck table can be performed every time grinding is performed on all of the wafers W accommodated in the first cassette 7. Furthermore, when the method for checking for clogging of the chuck table according to the present invention is performed periodically, it may be performed every time grinding is performed on a predetermined number of wafers W, or every time the operating time of the grinding apparatus 1 exceeds a certain period of time.

[0051] (Grinding process) In either of the above-described methods for checking for clogging of the chuck table (Example 1 and Example 2), if it is determined that clogging has occurred on the suction surface 61 of the chuck table 6, it is preferable to carry out a grinding process in which the suction surface 61 of the chuck table 6 is ground to eliminate the clogging and restore the suction force.

[0052] In the grinding process, for example, the turntable 5 of the grinding apparatus 1 described with reference to FIG. 1 is rotated in the direction indicated by arrow R3, and the chuck table 6 in which clogging was detected in the clogging determination process is positioned directly below the rough grinding unit 3, as shown in FIG. 8. Next, the grinding wheel 33 of the rough grinding unit 3 is rotated in the direction indicated by arrow R1 at a predetermined rotational speed (e.g., 6000 rpm), and the chuck table 6 is rotated in the direction indicated by arrow R4 at a predetermined rotational speed (e.g., 300 rpm). Next, the grinding feed mechanism 39 is operated to lower the rough grinding unit 3 in the direction indicated by arrow R5 until it abuts against the suction surface 61 of the chuck table 6 and is then ground at a predetermined grinding feed rate (e.g., 1.0 μm / s). At this time, grinding water can be supplied to the grinding region between the grinding wheel 34 and the suction surface 61 of the chuck table 6 via the rotating shaft 32 by a water supply means (not shown). 8, a water supply source 60 is connected to the chuck table 6 of this embodiment via a water supply path 53, and when the suction surface 61 is ground by the rough grinding unit 3, it is preferable to open an on-off valve 54 disposed in the water supply path 53 to supply water L from the water supply source 60 via the water supply path 53 and spray it from the suction surface 61 of the chuck table 6. Then, the suction surface 61 is ground together with the frame 62 by about 100 μm, and grinding of the suction surface 61 of the chuck table 6 is completed. This eliminates clogging on the suction surface 61 of the chuck table 6 and restores the suction force.

[0053] The confirmation plate of the above embodiment allows the user of the grinding device to quantitatively determine clogging, and solves the problem that as clogging progresses, it becomes difficult to restore suction force through maintenance, making it necessary to replace the chuck table with a new one, which is uneconomical.

[0054] Furthermore, the above-described method for checking clogging of the chuck table allows the user of the grinding device to quantitatively determine clogging, and the problem that as clogging progresses, it becomes difficult to restore suction force through maintenance, making it necessary to replace the chuck table with a new one, which is uneconomical, is resolved.

[0055] In the above embodiment, the confirmation plate is stored in the confirmation plate storage cassette 16 arranged in the grinding device 1 and is removed from the confirmation plate storage cassette 16 as needed, but it is not necessary to provide the confirmation plate storage cassette 16, and the operator may carry the confirmation plate 15 into the grinding device 1 each time he or she uses the confirmation plate 15 to check for clogging on the suction surface 61 of the chuck table 6. [Explanation of symbols]

[0056] 1: Grinding device 2: Device housing 21:Supporting wall 22: Guide rail 23: Guide rail 3: Rough grinding unit 31: Unit housing 32: Rotation axis 33: Wheel mount 34: Grinding wheel 35: Grinding wheel 36: Electric motor 37: Support member 38: Mobile base 39: Grinding feed mechanism 4: Finish grinding unit 41: Unit housing 42: Rotation axis 43: Wheel mount 44: Grinding wheel 45: Grinding wheel 46: Electric motor 47: Support member 48: Mobile base 49: Grinding feed mechanism 5: Turntable 6: Chuck table 61: Suction surface 61a: Outer perimeter 62: Frame 7: First Cassette 8: Second cassette 9: Temporary table 10: Cleaning water supply nozzle 11: Cleaning method 12: Workpiece loading / unloading means 13: First conveyance means 14: Second transport means 15: Confirmation plate 15a: Outer circumference 16: Confirmation plate storage cassette 17: Cleaning water supply nozzle 50: Suction source 51: Suction path 60: Water source 100: Control means 110: Pressure sensor

Claims

1. A confirmation plate for confirming clogging of a chuck table in a grinding apparatus including a suction surface for suction-holding a wafer and a chuck table having a frame surrounding the suction surface, and grinding means for grinding the wafer held on the chuck table, comprising: A confirmation plate having a diameter slightly smaller than the diameter of the suction surface of the chuck table.

2. A method for checking clogging of a chuck table using the check plate according to claim 1, a placing step of placing the confirmation plate on a suction surface of the chuck table; a suction and holding step of generating a suction force on the suction surface to suction and hold the confirmation plate; a measuring step of measuring a pressure in a suction path of the chuck table; Equipped with The method for checking for clogging in a chuck table includes a clogging determination step of determining that clogging has occurred on the outer periphery of the suction surface of the chuck table when the pressure in the suction path is reduced and the measured value becomes equal to or less than a predetermined value in the measurement step.

3. A method for checking clogging of a chuck table using the check plate according to claim 1, a placing step of placing the confirmation plate on a suction surface of the chuck table; a suction and holding step of generating a suction force on the suction surface to suction and hold the confirmation plate; a water supplying step of supplying water to the outer periphery of the confirmation plate; a measuring step of measuring a pressure in a suction path of the chuck table; Equipped with The clogging checking method for a chuck table includes a clogging determining step of stopping the suction of the chuck table in the suction holding step, blocking the outer periphery of the confirmation plate with water in the water supplying step, and measuring the time from when the pressure in the suction path of the chuck table drops by activating the suction of the chuck table to when the supplied water is sucked in, the water disappears from the outer periphery of the confirmation plate, and the pressure in the suction path rises, and if the measured time exceeds a predetermined time, determining that clogging has occurred on the outer periphery of the suction surface.

4. 4. The method for checking clogging of a chuck table according to claim 2, wherein the clogging determination step is carried out periodically.

5. 4. The method for checking for clogging of a chuck table according to claim 2, further comprising, if it is determined in the clogging determination step that clogging has occurred on the suction surface of the chuck table, a grinding step of grinding the suction surface of the chuck table to eliminate the clogging and restore suction force.

Images