Checking jig and use method of the same

Abstract

To provide a checking jig 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 jig checks clogging of a chuck table in a grinding device which is formed including: a suction surface which suctions and holds a wafer; a chuck table formed by a frame body enclosing the suction surface; and grinding means which grinds the wafer held by the chuck table. The checking jig includes: plates 15a, 16a having diameters corresponding to a diameter of the wafer; and openings 15b, 16b respectively formed at outer peripheries of the plates 15a, 16a.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a checking jig for checking clogging of a chuck table and a method of using the checking jig. [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 is configured to include a suction surface that holds the wafer by suction, a chuck table consisting of 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 grinding debris 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 contamination including the grinding debris (hereinafter referred to as "contamination"), resulting in a problem of 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 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 method of determining clogging also differs. 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 checking jig and a method of using the checking jig that can properly 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 therefore 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 jig for confirming clogging of a chuck table in a grinding apparatus configured to include a suction surface that suction-holds a wafer, a chuck table consisting of a frame body surrounding the suction surface, and grinding means that grinds the wafer held on the chuck table, the confirmation jig comprising a plate having a diameter corresponding to the diameter of the wafer and an opening formed on the outer periphery of the plate.

[0009] The openings may be configured to be a plurality of slit-shaped openings formed on the inner side adjacent to the outer periphery of the plate, or may be formed by gear-shaped notches on the outer periphery of the plate.

[0010] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a method of using the above-mentioned confirmation jig, comprising: a placing step of placing the confirmation jig on the suction surface of the chuck table; a suction holding step of generating a suction force on the suction surface to hold the confirmation jig by suction; and a measuring step of measuring the pressure in the suction path of the chuck table, and further comprising a clogging determining 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 in the measuring step and the measured value becomes a predetermined value or less.

[0011] Furthermore, in order to solve the above-mentioned main technical problem, according to the present invention, there is provided a method of using the above-mentioned confirmation jig, comprising: a placing step of placing the confirmation jig 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 jig by suction; a water supply step of supplying water to an opening of the confirmation jig; 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 opening of the confirmation jig is blocked 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 of the opening 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.

[0012] 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]

[0013] The confirmation jig of the present invention is a confirmation jig for checking for clogging of the chuck table of a grinding apparatus configured to include a suction surface that suction-holds a wafer, a chuck table consisting of a frame surrounding the suction surface, and grinding means that grinds the wafer held on the chuck table.The confirmation jig of the present invention is equipped with a plate having a diameter corresponding to the diameter of the wafer and an opening formed on the outer periphery of the plate, thereby allowing users of the grinding apparatus to quantitatively determine clogging, and solving 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.

[0014] Furthermore, a method of using the confirmation jig of the present invention comprises a placing step of placing the confirmation jig on the suction surface of the chuck table, a suction holding step of generating a suction force on the suction surface to hold the confirmation jig by suction, 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 in the measuring step and the measured value falls below a predetermined value.This eliminates the problem that clogging can be quantitatively determined by the user of the grinding machine, and that as the clogging progresses it becomes difficult to restore suction force through maintenance, necessitating the uneconomical replacement of the chuck table with a new one.

[0015] Furthermore, a method of using the confirmation jig of the present invention comprises a placing step of placing the confirmation jig 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 jig by suction, a water supply step of supplying water to an opening of the confirmation jig, 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 opening of the confirmation jig is blocked 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 of the opening 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]

[0016] [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] 1A is a perspective view showing an embodiment of a confirmation jig configured based on the present invention, and FIG. 1B is a perspective view showing another embodiment of the confirmation jig. [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

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a confirmation jig configured according to the present invention and a method of using the confirmation jig will be described in detail with reference to the accompanying drawings.

[0018] FIG. 1 shows a grinding apparatus 1 suitable for the confirmation jig and method of using the confirmation jig of this embodiment, which will be described later. The grinding apparatus 1 includes a chuck table 6 that suction-holds a wafer W 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 suction-holds the wafer W, which is the workpiece, 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 jig and method of using the confirmation jig of the present invention are applicable 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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 grinding apparatus 1 is provided with a workpiece carry-in / out means 12 that 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 that transports the wafer W held on the temporary placement table 9 onto the chuck table 6 positioned in the workpiece carry-in / out area A, and a second transport means 14 that transports the ground wafer W placed on the chuck table 6 positioned in the workpiece carry-in / out area A to the cleaning means 11. Note that the grinding apparatus 1 is not limited to the configuration provided with the first transport means 13 and the second transport means 14 described above, and may be provided with one transport means that serves as both the first transport means 13 and the second transport means 14. The single transport means may transport the unprocessed wafer W from the temporary storage table 9 to the chuck table 6 positioned in the workpiece loading / unloading area A, and transport the wafer W after grinding from the chuck table 6 positioned in the workpiece loading / unloading area A to the cleaning means 11.

[0028] 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 using the checking jig of this embodiment for checking for clogging of the chuck table 6 (described in detail later).

[0029] 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.

[0030] The confirmation jig of the present invention comprises a plate having a diameter corresponding to the diameter of the wafer W and an opening formed on the outer periphery of the plate. Figure 3(a) shows confirmation jig 15, which is an embodiment constructed based on the present invention, and Figure 3(b) shows confirmation jig 16, which is another embodiment constructed based on the present invention.

[0031] The checking jig 15 shown in FIG. 3(a) includes a plate 15a having a diameter S1 corresponding to the diameter (e.g., 150 mm) of the wafer W housed in the first cassette 7, and a slit 15b formed as an opening penetrating vertically on the inner side of the plate 15a adjacent to the outer periphery 15c. The diameter of the wafer W corresponds to the diameter of the suction surface 61 of the chuck table 6, and the diameter S1 of the plate 15a of the checking jig 15 also corresponds to the diameter of the suction surface 61 of the chuck table 6. The slits 15b of the checking jig 15 shown in the figure are formed in a shape that follows the shape of the outer periphery 15c, and four slits 15b are formed at equal intervals. The slits 15b are set in correspondence with the outer periphery region of the suction surface 61 of the chuck table 6 where clogging is expected to occur, and are formed, for example, within a range of 4 to 5 mm inward from the outer periphery 15c. The width, length, and number of the slits 15b can be set as desired.

[0032] 3(b), the confirmation jig 16 includes a plate 16a having a diameter S2 corresponding to the diameter (e.g., 150 mm) of the wafer W accommodated in the first cassette 7, and a gear-shaped notch 16b formed along an outer periphery 16d of the plate 16a. The notch 16b is formed by a plurality of protrusions 16c formed at equal intervals on the outer periphery 16d of the plate 16a, and, like the slit 15b described above, is set in correspondence with the outer periphery region where clogging is expected to occur on the suction surface 61 of the chuck table 6, and is formed within a range of 4 to 5 mm inward from the outer periphery 16d.

[0033] The following describes how to use the above-mentioned confirmation jigs 15 and 16. Note that, in the method of using the confirmation jigs described below, the above-mentioned confirmation jig 15 is used, but similar effects can be obtained even when confirmation jig 16 is used. First, Example 1 of the method of using the confirmation jig configured based on the present invention will be described.

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

[0035] As described above, the confirmation jig 15 of this embodiment has a diameter S1 corresponding to the diameter of the wafers W accommodated in the first cassette 7. The confirmation jig 15 is accommodated in the first cassette 7 together with a plurality of wafers W, which are the workpieces, and is then loaded into the grinding apparatus 1. The confirmation jig 15 loaded into the grinding apparatus 1 together with the first cassette 7 is then unloaded from the first cassette 7 by the workpiece loading / unloading means 12, for example, after grinding has been performed on all of the wafers W accommodated in the first cassette 7. It is preferable that the confirmation jig 15 be stored in the top or bottom row of the first cassette 7 and loaded into the grinding apparatus 1. The confirmation jig 15 is then loaded onto the temporary placement table 9, where it is centered. The first transport means 13 is then operated, and the confirmation jig 15 is placed on the suction surface 61 of the chuck table 6 positioned in the workpiece loading / unloading area A, as shown in FIG. 4 .

[0036] (Suction holding process) As described above, once the checking jig 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 Figure 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 above-mentioned suction surface 61 of the chuck table 6, thereby suction-holding the checking jig 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) FIG. 5B shows the change in pressure in the suction path 51 from the time (T0) when pressure measurement begins during the suction holding process described above. If no clogging occurs in the outer peripheral region of the suction surface 61 of the chuck table 6, the pressure measured by the pressure sensor 110 gradually decreases, as shown by L1 in FIG. 5B, but does not decrease significantly. After a predetermined time (e.g., T1), the pressure stabilizes at a pressure below P1, the reference value for determining clogging. In this case, the control unit 100 determines that no clogging occurs in the outer peripheral region 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 in the grinding apparatus 1, causing clogging in the outer peripheral region of the suction surface 61, the pressure in the suction path 51 decreases during the measurement process described above. After a predetermined time (e.g., T1), the pressure measurement drops to a pressure below P1, the reference value for determining clogging, and stabilizes at that low pressure. The pressure value P1, which is the reference value for judgment, 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 is equal to or less than the clogging judgment reference value P1, the control means 100 judges that clogging has occurred on the outer periphery of the suction surface 61 of the chuck table 6. The results of the clogging judgment process based on the first embodiment can be 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 can be notified by displaying a message to that effect on a display means (not shown). If it is determined that clogging has occurred on the suction surface 61, the operator can be 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. Furthermore, if it is determined that clogging has occurred in the clogging judgment process as described above, it is preferable to perform a grinding process (described below) to restore the suction force of the suction surface 61 of the chuck table 6. It is preferable to prohibit the 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 of using the confirmation jig configured based on the present invention is not limited to the above-described Example 1. Hereinafter, a method of using another confirmation jig configured based on the present invention (Example 2) will be described.

[0042] (Placement process) The placement process carried out in this embodiment 2 is similar to the placement process of the above-described embodiment 1, in that the confirmation jig 15 carried into the grinding device 1 is placed on 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-mentioned Example 1, the confirmation jig 15 is placed on the suction surface 61 of the chuck table 6, and then the on-off valve 52 shown in Figure 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-mentioned suction surface 61 of the chuck table 6, thereby suction-holding the confirmation jig 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 checking jig 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 onto the checking jig 15 placed and held on the chuck table 6, so that the water L is stored in at least four slits 15b of the checking jig 15 and blocks the slits 15b with the water L. Note that when the cleaning water supply nozzle 17 supplies the water L onto the checking jig 15 onto the checking jig 15, 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 stored in the four slits 15b. The method of supplying water L to the slit 15b of the checking jig 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 water L stored in slit 15b, opening / closing valve 52 of suction path 51 is opened to generate suction force V1 by suction source 50 on suction surface 61 of chuck table 6, and simultaneously, pressure in suction path 51 is measured by pressure sensor 110. The pressure measurement value measured by pressure sensor 110 is transmitted to control means 100 together with the elapsed time from pressure measurement start time 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 being stored in the slit 15b of the confirmation jig 15, which forms the opening of the present invention. Then, when the suction of the water L stored in the slit 15b is completed, air begins to be sucked directly through the slit 15b of the confirmation jig 15, 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 slit 15b is completed quickly, and the sharp drop in pressure ends at a relatively early time T2, as indicated by L3 in FIG. 7 . Then, air begins to be sucked through the slit 15b of the confirmation jig 15, 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 (e.g., 2 seconds). As can be seen from Fig. 7, if no clogging occurs in the outer peripheral region of the suction surface 61 of the chuck table 6, the pressure drop ends in a short time, and the pressure stabilizes at a relatively high value after the measured pressure value starts to rise.

[0048] In contrast, in the grinding apparatus 1, when contaminated processing water is sucked from the outer periphery of the wafer W held on the chuck table 6 to the suction surface 61 of the chuck table 6 and clogging occurs in the outer peripheral region of the suction surface 61, as shown by L4 in FIG. 7, the suction of the water L stored in the slit 15b is not completed quickly, the pressure drop is large, and it takes time for the measured pressure value to start increasing, finally starting to increase at time T3 in FIG. 7. As a result, 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 T3 when the measured pressure value starts to increase exceeds the above-mentioned predetermined time T4 (e.g., 2 seconds). As can be seen from FIG. 7, when clogging occurs in the outer peripheral region of the suction surface 61 of the chuck table 6, it takes time for the pressure drop to end, and the pressure after the measured pressure value in the suction path 51 starts to increase remains at a lower value than the above-mentioned L3.

[0049] 7, when a curve such as that indicated by L3 is detected, the control means 100 determines that clogging has occurred on the outer periphery of the suction surface 61 of the chuck table 6. The result determined by the clogging determination step performed based on the second embodiment can be notified to the operator by an appropriate method. The notification method may be the same as that of the first embodiment. When clogging is determined in the clogging determination step as described above, it is preferable to prohibit grinding of the wafer W by the grinding apparatus 1 until the clogging state is resolved.

[0050] The method of using the confirmation jig of this embodiment 1 described above can be carried out in the same procedure even when the confirmation jig 16 described above is used. Furthermore, it is preferable that the method of using the confirmation jig of this embodiment be carried out periodically. For example, one confirmation jig 15 (or confirmation jig 16) is stored in the first cassette 7, and the method of using the confirmation jig described above can be carried out every time a grinding process is carried out on a wafer W stored in the first cassette 7. Furthermore, when the method of using the confirmation jig carried out according to the present invention is carried out periodically, it may be carried out every time a predetermined number of wafers W are ground, or every time the operating time of the grinding apparatus 1 exceeds a certain time.

[0051] (Grinding process) In either of the above-described methods of using the confirmation jig (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, i.e., in the rough grinding processing area B. Next, as shown in FIG. 8, 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 ground at a predetermined grinding feed rate (e.g., 1.0 μm / s). At this time, grinding water can be supplied to the grinding processing area 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 checking jig 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 method of using the checking jig described above allows the user of the grinding machine to quantitatively determine clogging, and the problem of clogging progressing to the point where it becomes difficult to restore suction force through maintenance, necessitating replacement with a new chuck table and therefore eliminating the need for economical replacement, is solved.

[0055] The checking jig constructed according to the present invention has a diameter corresponding to the diameter of the wafers to be processed in the grinding device, and therefore, the checking jig can be stored, for example, in the upper or lower tier of a cassette that stores wafers, and can be taken out of the cassette at an appropriate time to automatically check for clogging of the chuck table, thereby preventing the operator from forgetting to check. [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 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: Check jig 15a: Plate 15b: Slit 15c: Outer circumference 16: Confirmation jig (another embodiment) 16a: Plate 16b: Notch 16c: Convex part 16d: Outer circumference 17: Cleaning water supply nozzle 50: Suction source 51: Suction path 60: Water source 100: Control means

Claims

1. A checking jig for checking clogging of a chuck table in a grinding apparatus including a suction surface for suction-holding a wafer, a chuck table having a frame surrounding the suction surface, and grinding means for grinding the wafer held on the chuck table, comprising: A verification jig comprising a plate having a diameter corresponding to the diameter of the wafer and an opening formed in the outer periphery of the plate.

2. 2. The checking jig according to claim 1, wherein the openings are formed in the shape of a plurality of slits on the inner side adjacent to the outer periphery of the plate.

3. 2. The verification tool according to claim 1, wherein the opening is formed by a gear-shaped notch in the outer periphery of the plate.

4. A method for using the confirmation jig according to any one of claims 1 to 3, a placing step of placing the confirmation jig on a suction surface of the chuck table; a suction holding step of generating a suction force on the suction surface to suction-hold the verification jig; a measuring step of measuring a pressure in a suction path of the chuck table; Equipped with The method of using the confirmation jig 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 in the measurement step and the measured value becomes equal to or less than a predetermined value.

5. A method for using the confirmation jig according to any one of claims 1 to 3, a placing step of placing the confirmation jig on a suction surface of the chuck table; a suction holding step of generating a suction force on the suction surface to suction-hold the verification jig; a water supplying step of supplying water to the opening of the confirmation jig; a measuring step of measuring a pressure in a suction path of the chuck table; Equipped with a clogging determination step of stopping the suction of the chuck table in the suction holding step, blocking the opening of the confirmation jig with water in the water supply step, and measuring 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 in, the water disappears from the opening, 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.

6. 6. The method for using the checking tool according to claim 4, wherein the clogging determining step is carried out periodically.

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

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