Grinding device

Abstract

To provide a grinding device that is configured so that when removing a chamfered part during grinding, the chamfered part dropping from a wafer can be prevented from breaking into fine scrap materials and accumulating in a drainage pan of the grinding device.SOLUTION: A grinding device, which grinds a surface of a wafer W, comprises: a scrap material capturing body 6 that includes a chuck table that can hold and rotate a wafer and grinding means 3 comprising a grinding wheel 34 in which a grinding stone 35 is arranged, which is arranged to surround the chuck table and captures scrap materials 12A dropping from an outer periphery of the wafer during grinding; positioning means 61 that positions the scrap material capturing body at an action position and at a non-action position; and scrap material collecting means 60 that collects the captured scrap materials. A recessed part 6e through which the grinding stone is allowed to pass is formed at an upper end part of the scrap material capturing body. When the scrap material capturing body is positioned at the action position, the upper end part of the scrap material capturing body is positioned at a position beyond an upper surface of the wafer, and a bottom of the recessed part is positioned at a position below the surface of the wafer, where the bottom of the recessed part can be avoided from contacting the grinding stone.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a grinding apparatus for grinding the surface of a wafer. [Background technology]

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

[0003] Furthermore, a chamfer is formed on the outer periphery of the wafer, and when the back surface of the wafer is ground to thin it, the chamfer becomes as sharp as a knife edge, which can injure an operator or cause cracks to form from the outer periphery of the wafer to the inside, damaging the device.

[0004] Therefore, a technique has been proposed in which, before grinding the back surface of the wafer, a portion of the chamfered portion is removed from the front surface of the wafer to a depth equivalent to the finished thickness of the wafer at the outer periphery corresponding to the chamfered portion (see, for example, Patent Document 1).

[0005] In particular, when processing a stacked wafer in which two wafers are stacked, it is conceivable to remove the chamfered portion of one wafer, the back surface of which is ground, before stacking the wafers, and then position the front surface of one wafer from which the chamfered portion has been removed on the front surface of the other wafer and stack them. However, if the chamfered portion of one wafer is completely removed, it becomes difficult to accurately align the center of one wafer with the center of the other wafer, so it is necessary to leave more than half of the chamfered portion of one wafer, but this processing is not easy.

[0006] Therefore, a technology has been proposed in which, before grinding the back surface of the wafer, a laser beam having a wavelength that is transparent to the wafer is irradiated at a focal point inside the chamfer, and a ring-shaped modified layer is formed inside the wafer, which serves as a starting point for separating the chamfer, thereby removing the chamfer during grinding (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-003198 [Patent Document 2] Japanese Patent Publication No. 2020-088187 Summary of the Invention [Problem to be solved by the invention]

[0008] When the chamfered portion is removed during grinding by the technology described in Patent Document 2, the chamfered portion that falls off the wafer becomes small scraps and accumulates in the drain pan of the grinding machine, which requires frequent cleaning, which is an unbearable hassle.

[0009] The present invention has been made in view of the above facts, and its main technical object is to provide a grinding apparatus that can solve the problem that when removing a chamfered portion during grinding, the chamfered portion that falls off from the wafer becomes fine scraps and accumulates in the drain pan of the grinding apparatus, requiring frequent cleaning, which is an unbearable hassle. [Means for solving the problem]

[0010] In order to solve the above-mentioned main technical problem, according to the present invention, a grinding device for grinding the surface of a wafer includes a rotatable chuck table for holding a wafer, and grinding means having a rotatable grinding wheel on which grinding stones are arranged in an annular shape for grinding the surface of the wafer held on the chuck table while supplying grinding water to the surface of the wafer, a scrap material catcher arranged to surround the chuck table and for capturing scrap materials that fall off from the outer periphery of the wafer during grinding, positioning means for positioning the scrap material catcher between an operating position and a non-operating position, and a grinding device for grinding the scrap material caught by the scrap material catcher. and scrap material collecting means for collecting scrap material collected by the grinding wheel, wherein a recess is formed at the upper end of the scrap material catcher to allow the grinding stone arranged on the grinding wheel to pass through, and when the scrap material catcher is positioned in the operating position by the positioning means, the upper end of the scrap material catcher is positioned above the upper surface of the wafer held on the chuck table, and the bottom of the recess is positioned below the surface of the wafer held on the chuck table to avoid contact with the grinding stone, thereby providing a grinding device for grinding the wafer held on the chuck table.

[0011] The scrap recovery means preferably includes an annular container consisting of an annular inner wall surrounding the chuck table, an annular outer wall, a bottom wall connecting the inner wall and the outer wall, and a discharge section for discharging scrap, an annular ring guide arranged on the chuck table and guiding scrap that falls off the outer periphery of the wafer to the annular container, drain means having a scrap receiving section communicating with the discharge section of the annular container, and scrap storage means arranged at the other end of the drain means.

[0012] The drain means preferably includes a main drain, a first drain and a second drain branched from the main drain, and a selector for selecting between the first drain and the second drain. The chuck table is preferably disposed in a drain pan for receiving grinding water, the drain pan having a drain port and a drain drain communicating with the drain port, and an end of the drain drain connected to the main drain.

[0013] The annular vessel preferably includes a scrap nozzle for supplying water to sweep the scrap into the discharge area. [Effects of the Invention]

[0014] The grinding device of the present invention is a grinding device for grinding the surface of a wafer, and includes a rotatable chuck table for holding a wafer, and grinding means having a rotatable grinding wheel on which grinding stones are arranged in an annular shape for grinding the surface of the wafer held on the chuck table while supplying grinding water to the surface of the wafer, a scrap catcher arranged to surround the chuck table and for capturing scraps that fall off from the outer periphery of the wafer during grinding, positioning means for positioning the scrap catcher between an active position and a non-active position, and scrap collecting means for collecting the scraps captured by the scrap catcher, and the upper end of the scrap catcher is provided with a grinding stone arranged on the grinding wheel. A recess is formed to allow stones to pass through, and when the scrap catcher is positioned in its operating position by the positioning means, the upper end of the scrap catcher is positioned above the upper surface of the wafer held on the chuck table, and the bottom of the recess is positioned below the surface of the wafer held on the chuck table to avoid contact with the grinding wheel, thereby grinding the wafer held on the chuck table.As a result, even if the outer edge of the wafer falls off as scrap, it is collected by the scrap collection means, eliminating the problem of scrap remaining in the drain pan of the grinding device, which requires frequent cleaning and is an unbearable hassle. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is an overall perspective view of the grinding device. [Figure 2] 2(a) is a perspective view showing an example of a wafer ground by the grinding apparatus shown in FIG. 1, and FIG. 2(b) is a perspective view showing another example of a wafer ground by the grinding apparatus shown in FIG. [Figure 3] 2 is an exploded perspective view showing an end material catcher, a ring guide, and an annular container disposed in the grinding device shown in FIG. 1. FIG. [Figure 4]1A is a perspective view showing an embodiment in which the scrap catcher is integrated with the annular container and is in a non-operating position, and FIG. 1B is a partially enlarged cross-sectional view of the embodiment shown in FIG. [Figure 5] FIG. 10A is a perspective view showing an embodiment in which the scrap catcher is integrated with the annular container and is in an operative position, and FIG. 10B is a partially enlarged cross-sectional view of the embodiment shown in FIG. [Figure 6] FIG. 2 is a perspective view showing the entire scrap collection means including the scrap catcher and the drain means. DETAILED DESCRIPTION OF THE INVENTION

[0016] The grinding device of the present invention includes a rotatable chuck table for holding a wafer as a workpiece, and grinding means having a rotatable grinding wheel with annularly arranged grinding stones for grinding the surface of the wafer held on the chuck table while supplying grinding water to the surface of the wafer, a scrap catcher disposed around the chuck table for capturing scraps that fall off from the outer periphery of the wafer during grinding, scrap recovery means for recovering the scraps captured by the scrap catcher, and a mechanism for moving the scrap catcher between an operating position and a non-operating position. and a positioning means for positioning the scrap collection unit, the upper end of the scrap catcher having a recess formed therein that allows a grinding stone disposed on the grinding wheel to pass through, and when the scrap catcher is positioned at an operating position by the positioning means, the upper part of the scrap catcher is positioned above the upper surface of the wafer, and the bottom of the recess is positioned below the surface of the wafer to avoid contact with the grinding stone, thereby grinding the surface of the wafer held on the chuck table. Hereinafter, an embodiment of a grinding device configured based on the present invention will be described in detail with reference to the accompanying drawings.

[0017] FIG. 1 shows a perspective view of a grinding apparatus 1 constructed according to the present invention. The illustrated grinding apparatus 1 comprises a rotatable chuck table 5 for holding a wafer, a first grinding means 3 having a rotatable grinding wheel 34 on which grinding stones 35 are arranged in a ring shape to perform rough grinding while supplying grinding water L to the surface of the wafer held on the chuck table 5, a second grinding means 4 having a rotatable grinding wheel 44 on which grinding stones 45 are arranged in a ring shape to perform finish grinding while supplying grinding water L to the surface of the wafer that has been subjected to rough grinding, a scrap capture body 6 arranged surrounding the chuck table 5 to capture scrap that falls off from the outer periphery of the wafer during grinding, a positioning means 61 (see also Figure 3, described in detail later) for positioning the scrap capture body 6 between an active position and a non-active position, and a scrap collection means 60 (shown by dashed lines) for collecting scrap captured by the scrap capture body 6.

[0018] Here, an example of a wafer to be ground by the grinding apparatus 1 will be described with reference to Fig. 2. Note that the wafer shown in Fig. 2 is merely one example of a wafer to be processed by the grinding apparatus 1, and is not particularly limited to this as long as it is a wafer from which the outer peripheral edge needs to be removed.

[0019] FIG. 2(a) shows a stacked wafer W, which serves as a workpiece in the grinding apparatus 1. As shown, the stacked wafer W is a wafer formed by stacking a first wafer 10A and a second wafer 10B together. The first wafer 10A is, for example, a silicon wafer having a diameter of 300 mm and a thickness of 700 μm. The wafer 10A has a central effective area in which a device (not shown) to be used as a product is formed, and a chamfered portion 12A formed at the edge of the periphery of a peripheral excess area surrounding the effective area. The second wafer 10B has a similar configuration to the first wafer 10A and, although not shown, is a silicon wafer on whose surface a plurality of devices are formed and partitioned by planned division lines. The laminated wafer W is formed by, for example, bonding the surface of the first wafer 10A and the surface of the second wafer 10B together face to face and then subjecting them to heat treatment to form a siloxane bond.

[0020] Within the boundary separating the effective region and the peripheral excess region of the first wafer 10A constituting the stacked wafer W, an annular modified layer 100 is formed along the entire periphery of the chamfered portion 12A of the first wafer 10A, serving as a separation starting point for separating the chamfered portion 12A. The modified layer 100 can be formed by positioning the focal point of a laser beam having a wavelength that is transparent to the silicon constituting the stacked wafer W inside the boundary of the first wafer 10A, irradiating the laser beam, and rotating the stacked wafer W. Preferably, multiple modified layers 100 are formed in the depth direction, for example, four layers. The stacked wafer W is formed by grinding the back surface 10Ab of the first wafer 10A using a grinding apparatus 1, and removing the peripheral chamfered portion 12A.

[0021] FIG. 2(b) shows a wafer 10C as another example of a wafer to be ground by the grinding apparatus 1 of this embodiment. The wafer 10C is a single wafer, e.g., a silicon wafer with a diameter of 300 mm and a thickness of 700 μm. A plurality of devices 12C are formed on the front surface 10Ca, partitioned by planned division lines 14C. The wafer 10C has a front surface 10Ca and a back surface 10Cb. The wafer 10C includes a central effective area 16C in which the devices 12C to be used as products are formed, and a chamfered portion 17C formed at the edge of the periphery of a peripheral excess area 18C surrounding the effective area 16C. The peripheral excess area 18C corresponding to the chamfered portion 17C on the front surface 10Ca of the wafer 10C is edge-trimmed to remove a portion of the chamfered portion 17C to a depth corresponding to the finished thickness of the wafer 10C, forming a step. When grinding using the grinding device 1 of the embodiment, a protective tape (not shown) is attached to the surface 10Ca side, the protective tape side is placed and held on the chuck table 5, and the back surface 10Cb is ground to remove the chamfered portion 17C on the periphery.

[0022] In the following description, the functions, actions, and effects of the grinding apparatus 1 of this embodiment will be described using as an example a case where the above-described laminated wafers W are carried into the grinding apparatus 1 and ground.

[0023] Returning to Figure 1, the grinding apparatus 1 includes a roughly rectangular parallelepiped housing 2, with a support wall 2a erected on the rear end side of the housing 2. Two pairs of guide rails 2b, 2b and 2c, 2c extending in the vertical direction are provided on the inner surface of this support wall 2a. The grinding apparatus 1 is provided with two grinding means, with a first grinding means 3 as rough grinding means attached to one of the guide rails 2b, 2b so as to be movable in the vertical direction, and a second grinding means 4 as finish grinding means attached to the other guide rail 2c, 2c so as to be movable in the vertical direction.

[0024] The first grinding means 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 grinding wheel 34 attached to the wheel mount 33 and having a grinding stone 35 for rough grinding arranged in a ring shape on its underside, an electric motor 36 attached to the upper end of the unit housing 31 to rotate the rotating shaft 32, and a movable base 37 supporting the unit housing 31.

[0025] The movable base 37 is provided with guided grooves that slidably engage with the guide rails 2b, 2b, and supports the first grinding means 3 so that it can move up and down. The grinding apparatus 1 also includes a grinding feed means 38 that raises and lowers the movable base 37 of the first grinding means 3 along the guide rails 2b, 2b, and moves the first grinding means 3 toward and away from the chuck table 5. The grinding feed means 38 includes a male-threaded rod (not shown) that is rotatably supported and disposed in parallel with the guide rails 2b in the vertical direction on the back side of the support wall 2a, a pulse motor 38a for driving the male-threaded rod, and a female-threaded block (not shown) that is attached to the movable base 37 and threadedly engages with the male-threaded rod on the back side of the support wall 2a. The male-threaded rod is driven forward and backward by the pulse motor 38a, thereby moving the first grinding means 3 up and down.

[0026] The second grinding means 4 for performing finish grinding is configured in substantially the same manner as the first grinding means 3 described above, and comprises a unit housing 41, a wheel mount 43 disposed at the lower end of a rotating shaft 42 rotatably supported by the unit housing 41, a grinding wheel 44 attached to the wheel mount 43 and having a circularly arranged grinding stone 45 for finish grinding on its underside, an electric motor 46 attached to the upper end of the unit housing 41 for rotating the wheel mount 43, and a movable base 47 for supporting the unit housing 41.

[0027] The movable base 47 is provided with guided grooves that slidably engage with the guide rails 2c, 2c, and supports the second grinding means 4 so that it can move up and down. The grinding apparatus 1 also includes a grinding feed means 48 that raises and lowers the movable base 47 of the second grinding means 4 along the guide rails 2c, 2c, and moves the second grinding means 4 toward and away from the chuck table 5. The grinding feed means 48 includes a male-threaded rod (not shown) that is rotatably supported and disposed in parallel with the guide rails 2c in the vertical direction on the back side of the support wall 2a, a pulse motor 48a for driving the male-threaded rod, and a female-threaded block (not shown) that is attached to the movable base 47 and threadedly engages with the male-threaded rod on the back side of the support wall 2a. The second grinding means 4 is moved up and down by the pulse motor 48a driving the male-threaded rod in forward and reverse directions.

[0028] A grinding water supply means 49 that supplies grinding water L via a grinding water supply path 49a is connected to the first grinding means 3 and the second grinding means 4. When the first grinding means 3 and the second grinding means 4 are operating, the grinding water L is introduced from the upper ends 32a, 42a of the rotation shafts 32, 42 of the electric motors 36, 46 and supplied to the chuck table 5 from the underside of the grinding wheels 34, 44.

[0029] The grinding apparatus 1 is provided with a turntable 2d disposed on the front side of the support wall 2a so as to be substantially flush with the upper surface of the apparatus housing 2. The turntable 2d is formed in a disk shape with a relatively large diameter, and is rotated appropriately by a rotation drive mechanism (not shown) within a drain pan 2e that receives grinding water L containing grinding chips on the upper surface of the apparatus housing 2. Four chuck tables 5 are disposed on the illustrated turntable 2d, each at an angle of 90 degrees. The drain pan 2e is provided with drain ports 2f through which the grinding water L received in the drain pan 2e is discharged when the stacked wafers W are ground by the first grinding means 3 and the second grinding means 4.

[0030] As the turntable 2d is rotated in the direction indicated by the arrow R1, the four chuck tables 5 arranged on the turntable 2d are moved sequentially from a carry-in area A where stacked wafers W, which are workpieces, are carried into the chuck table 5, to a first grinding area B where rough grinding is performed by the first grinding means 3, to a second grinding area C where finish grinding is performed by the second grinding means 4, to an unloading area D where the stacked wafers W after finish grinding are carried out, and back to the carry-in area A. Furthermore, optical non-contact thickness detecting means (not shown) for detecting the thickness (height) of the stacked wafers W held on the chuck table 5 is arranged in the drain pan 2e at positions adjacent to the first grinding area B and the second grinding area C.

[0031] The illustrated grinding apparatus 1 includes a first cassette 7a disposed on the side of the carry-in area A and accommodating a plurality of stacked wafers W before grinding, a second cassette 7b disposed on the side of the carry-out area D and accommodating a plurality of stacked wafers W after grinding, an alignment means 8 disposed between the first cassette 7a and the carry-in area A and on which the stacked wafers W are temporarily placed and centered, a cleaning means 9 disposed between the carry-out area D and the second cassette 7b, and a cleaning device 10 for aligning the stacked wafers W accommodated in the first cassette 7a. The wafer transfer system includes a first transfer means 11A that transfers the stacked wafers W that have been finish-ground by the second grinding means 4 and then cleaned and dried by the cleaning means 9 to the second cassette 7b, a second transfer means 11B that transfers the stacked wafers W that have been aligned on the alignment means 8 onto the chuck table 5 positioned in the loading area A, and a third transfer means 11C that transfers the stacked wafers W that have been finish-ground by the second grinding means 4 and held on the chuck table 5 positioned in the unloading area D to the cleaning means 9.

[0032] The grinding machine 1 is provided with a control means 20 including an operation panel that controls each of the above-mentioned operating parts. The control means 20 is equipped with a central processing unit (CPU) that performs calculations according to a control program, a read-only memory (ROM) that stores the control program, etc., a readable and writable random access memory (RAM) that serves as storage means for storing calculation results, etc., an input interface, and an output interface (all of which are not shown). The control means 20 configured in this manner controls each of the above-mentioned operating parts of the grinding machine 1, and also displays information about processing, etc., as appropriate, on a display means not shown.

[0033] In addition to Figure 1, as shown in Figures 3 to 6, the grinding apparatus 1 of this embodiment is equipped with a scrap capture body 6 that is arranged surrounding the chuck table 5 and captures the chamfered portion 12A (scrap) separated from the outer periphery of the stacked wafers W when rough grinding is performed on the stacked wafers W by the first grinding means 3, a positioning means 61 that positions the scrap capture body 6 between an active position and a non-active position, and a scrap collection means 60 that collects the scrap 12A captured by the scrap capture body 6.The configurations of the scrap capture body 6, the positioning means 61, and the scrap collection means 60 will be described in more detail below.

[0034] 3 shows an exploded view of the scrap catcher 6, positioning means 61, and an annular container 62 that constitutes part of the scrap collection means 60. As shown in the figure, the scrap catcher 6 has a central opening 6a that is slightly larger than the diameter of the chuck table 5, an annular upper end 6b that surrounds the opening 6a, and a side wall 6c that hangs down along the outer periphery of the upper end 6b. The upper end 6b of the scrap catcher 6 has recesses 6e, 6e with bottoms 6f, 6f that allow the grinding stone 35 disposed on the grinding wheel 34 of the first grinding means 3 to pass through. The side wall 6c has multiple connecting portions 6d (three in the illustrated embodiment) to which the positioning means 61, described below, is connected.

[0035] 3, the annular container 62 is configured to include an annular inner wall 62a surrounding the chuck table 5, an annular outer wall 62b, a bottom wall 62c connecting the inner wall 62a and the outer wall 62b at their lower ends, and a discharge portion 62d that discharges scraps separated from the stacked wafers W. As shown in an exploded view on the right side of the figure, a nozzle hole 62e is formed on the opposite side of the discharge portion 62d in the outer wall 62b of the annular container 62, and a scrap nozzle 66 is inserted so that an injection hole 66a of the scrap nozzle 66 is positioned in a discharge path formed by the inner wall 62a, the outer wall 62b, and the bottom wall 62c. The scrap nozzle 66 is connected to a water supply means (not shown) (the grinding water supply means 49 described above can be used), which can spray water (grinding water L) that washes away the scraps separated from the stacked wafers W and collected in the annular container 62 toward the discharge portion 62d. As shown on the right side of the figure, the chuck table 5 is inserted into a central opening formed by the inner wall 62a of the annular container 62. The chuck table 5 has a breathable holding surface 5a and a frame portion 5b surrounding the holding surface 5a, and a stepped portion 5c is formed in an annular shape on the outer peripheral side surface of the frame portion 5b. The annular container 62 is formed with three connecting portions 62f corresponding to the connecting portion 6d formed on the scrap capture body 6 described above.

[0036] As shown in FIG. 3, the annular container 62 is positioned to surround the chuck table 5, and the opening 64a of the annular ring guide 64, which guides scraps separated from the outer periphery of the stacked wafers W held on the chuck table 5 into the annular container 62, is positioned and attached from above to the above-mentioned step portion 5c of the chuck table 5. Furthermore, the scrap catcher 6 is attached to the annular container 62 from above and integrated with it. The upper surface 64b of the ring guide 64 slopes downward as it approaches the outside, and the outer dimensions of the ring guide 64 are formed to be slightly larger than the diameter of the inner wall 62a of the annular container 62. When integrating the scrap catcher 6 and the annular container 62, the connecting portion 6d of the scrap catcher 6 and the connecting portion 62f of the annular container 62 are aligned so that they coincide with each other, and they are connected by the tip of the lifting rod 61a of the positioning means 61 to form an integrated unit (see also FIG. 4).

[0037] 4(a) and 4(b), by operating the positioning means 61 to lower the lifting rod 61a in the direction indicated by arrow R1 and thereby lowering the scrap catcher 6 and the annular container 62, the upper end 6b of the scrap catcher 6 is positioned at a position (non-operating position) lower than the upper surface of the stacked wafers W (indicated by the dashed line) held on the chuck table 5. Also, as shown in FIGS. 5(a) and 5(b), by operating the positioning means 61 to raise the lifting rod 61a in the direction indicated by arrow R2 and thereby raise the scrap catcher 6 and the annular container 62, the upper end 6b of the scrap catcher 6 is positioned at a position (operating position) higher than the upper surface of the stacked wafers W (indicated by the dashed line) held on the chuck table 5.

[0038] The scrap catcher 6 is positioned in the first grinding region B together with the chuck table 5, and is raised to its operating position by the positioning means 61 (see FIGS. 5(a) and 5(b)). When the grinding feed means 38 is operated to position the first grinding means 3 in contact with the upper surface of the stacked wafers W held on the chuck table 5, the recesses 6e, 6e of the scrap catcher 6 are set to allow the grinding wheel 35 of the first grinding means 3 to pass through, and the bottoms 6f, 6f of the recesses 6e, 6e are positioned below the surface of the stacked wafers W held on the chuck table 5, thereby being positioned at a height that avoids contact with the grinding wheel 35. The scrap catcher 6, annular container 62, and ring guide 64 are disposed on each of the four chuck tables 5 disposed on the turntable 2d, and rotate together with the chuck table 5 as the turntable 2d rotates.

[0039] As shown in FIG. 1, a drain means 63, which constitutes the scrap collection means 60 together with an annular container 62 and a ring guide 64 for collecting scrap captured by the scrap capture body 6, is disposed in a position corresponding to the first grinding region B of the device housing 2. The drain means 63 is installed inside the device housing 2 and in the space formed under the floor on which the grinding device 1 is installed. A portion of the lower side of the drain means 63 is omitted in FIG. 1, and an overall view of the scrap collection means 60 is shown in FIG. 6. As shown in FIG. 6, the discharge portion 62d of the annular container 62 is connected to a scrap receiving portion 63a formed at one end (upper end) of the drain means 63. The drain means 63 includes a main drain 63b with the scrap receiving portion 63a formed at its upper end, a first drain 63c and a second drain 63d branching from the main drain 63b, and a selector 65 for selecting the flow from the main drain 63b between the first drain 63c and the second drain 63d. Scrap receiving means 70A, 70B for receiving scrap 12A collected by the drain means 63 are disposed at the lower ends 63e, 63f of the first drain 63c and the second drain 63d of the drain means 63. For ease of explanation, FIG. 6 shows the scrap receiving means 70B removed. The drain means 63 will be described in more detail with reference to FIG. 6. In this embodiment, the drain means 63 constituting the scrap collecting means 60 is described as being large-scale, with priority given to the amount of scrap 12A collected, and is installed inside the device housing 2 and in a space formed under the floor on which the grinding device 1 is installed. However, the present invention does not exclude the drain means 63 being compactly formed so that the entirety of the drain means 63 can be accommodated inside the device housing 2.

[0040] The main drain 63b is connected to an end of a waste drain 50 provided in the drain pan 2e and having a drain outlet 50a connected to the drain outlet 2f of the drain pan 2e, and the grinding water L introduced via the drain outlet 2f of the drain pan 2e flows through the waste drain 50 and into the main drain 63b. The selection unit 65 is provided with a switch valve 65a at the connection between the main drain 63b and the first drain 63c and the second drain 63d. By operating the switch lever 65b of the selection unit 65 in the direction indicated by arrow R3, the position of the switch valve 65a is switched, and the flow direction of the grinding water L flowing from the main drain 63b and the scraps 12A separated from the first wafer 10A can be switched between the first drain 63c side and the second drain 63d side. In the embodiment shown in FIG. 6, the selector 65 switches the switching valve 65a to close the second drain 63d side, and the main drain 63b is connected to the first drain 63c side.

[0041] Offcut storage means 70A is attached to the lower end 63e of the first drain 63c. An exploded perspective view of offcut storage means 70A is shown on the right side of Figure 6. Offcut storage means 70A comprises a mesh bag member 71A and a cup-shaped member 72A. The mesh bag member 71A is a flexible and stretchable bag made, for example, of a resin net. It is inserted into the inner wall of the cup-shaped member 72A and is folded back at a flange 73A formed on the upper edge of the cup-shaped member 72A. A plurality of drainage holes 74A are formed circumferentially at the lower end of the cup-shaped member 72A, connecting the inside and outside. As shown in the figure, scrap storage means 70A is attached to the lower end 63e of the first drain 63c. When scrap 12A and grinding water L reach scrap storage means 70A from the main drain 63b via the first drain 63c, the scrap 12A is collected in a mesh bag member 71A, and the grinding water L flows out through a drainage hole 74A. Although it is removed in Figure 6 for convenience of explanation, scrap storage means 70B is attached to the lower end 63f of the second drain 63d. The scrap storage means 70B has the same configuration as the scrap storage means 70A described above and includes a mesh bag member 71B and a cup-shaped member 72B. A flange 73B is formed on the upper edge of the cup-shaped member 72B, and a plurality of drainage holes 74B that connect the inside and outside are formed circumferentially at the lower end. When the scrap 12A and grinding water L reach the scrap storage means 70B from the main drain 63b via the second drain 63d, the scrap 12A is stored in the mesh bag member 71B, and the grinding water L flows out to the outside through the drainage holes 74B of the cup-shaped member 72B.

[0042] Below the first drain 63c and the second drain 63d, there are provided a rotating plate 67 that supports the scrap material storage means 70A, 70B attached to the first drain 63c and the second drain 63d so that they do not fall, and a drainage container 68 that rotatably supports the rotating plate 67 and receives the grinding water L discharged from the scrap material storage means 70A, 70B attached to the first drain 63c and the second drain 63d and discharges it to the outside through a drainage drain 68a.

[0043] As described above, the scrap 12A separated from the stacked wafers W via the drain means 63 is collected by the scrap storage means 70A, 70B, and therefore the scrap storage means 70A, 70B are periodically, for example, alternately removed from the drain means 63 to discard the collected scrap 12A, and the scrap storage means 70A, 70B covered with the mesh bag members 71A, 71B are then reattached. The procedure for attaching and removing the scrap storage means 70A, 70B will be described with reference to FIG. 6.

[0044] The rotating plate 67 is formed with a temporary placement hole 67a large enough to accommodate the cup-shaped members 72A and 72B of the waste material collection containers 70A and 70B, but smaller in diameter than the flanges 73A and 73B. When attaching the waste material collection means 70B to the lower end 63f of the second drain 63d, the waste material collection means 70B, with the mesh bag member 71B attached, is first temporarily placed in the temporary placement hole 67a of the rotating plate 67. As described above, the temporary placement hole 67a has a smaller diameter than the flanges 73B, so the waste material collection means 70B will not fall into the distribution container 68. Next, the rotating plate 67 is rotated in the direction indicated by arrow R4 to position the waste material collection means 70B directly below the lower end 63f of the second drain 63d. Since the center of the temporary placement hole 67a is set to coincide with the center of the lower end 63f by rotating the rotating plate 67, after positioning the scrap material storage means 70B directly below the lower end 63f of the second drain 63d, the scrap material storage means 70B can be lifted up and attached to the lower end 63f of the second drain 63d, and by moving the rotating plate 67 from that position, the scrap material storage means 70B can be supported by the rotating plate 67 and maintained in a state attached to the lower end 63f.

[0045] To remove the scrap receiving means 70A from the lower end 63e of the first drain 63c while the scrap receiving means 70B is attached to the lower end 63f of the second drain 63d, operate the selection lever 65b of the selection unit 65 to switch the switching valve 65a to a position where the first drain 63c side is closed. Next, rotate the rotating plate 67 in the direction indicated by R5 to position the temporary placement hole 67a directly below the scrap receiving means 70A attached to the lower end 63e of the first drain 63c. Then, by lowering the scrap receiving means 70A into the temporary placement hole 67a and temporarily placing it there, it can be removed from the lower end 63e of the first drain 63c. Once the scrap collection means 70A has been removed from the lower end 63e of the first drain 63c, the rotary plate 67 can be rotated in the direction indicated by arrow R4 to the position shown in Figure 6, thereby removing the scrap collection means 70A and disposing of the collected scrap 12A. To attach the scrap collection means 70A to the lower end 63e of the first drain 63c, the reverse procedure can be carried out.

[0046] The grinding apparatus 1 of this embodiment has a configuration generally as described above, and will be described as performing a grinding process in which the stacked wafers W described based on Figure 2 are ground to separate the chamfered portion 12A from the first wafer 10A and recover it as scrap material.

[0047] When grinding the stacked wafers W using the grinding apparatus 1, the unprocessed stacked wafers W are carried out from the first cassette 7a by the above-mentioned first transport means 11A and placed on the alignment means 8, and the centers of the stacked wafers W are aligned. Next, the second transport means 11B is operated to transport the stacked wafers W from the alignment means 8 to the chuck table 5 positioned in the loading area A, and the first wafer 10A is placed facing upward and held by suction by operating the suction means (not shown). At this time, the scrap capture body 6 is positioned at the non-operating position by the above-mentioned positioning means 61.

[0048] In the loading area A, the stacked wafers W are held on the chuck table 5, and then the turntable 2d is rotated 90° in the direction indicated by the arrow R1 in Fig. 1, and the chuck table 5 holding the stacked wafers W is positioned in the first grinding area B. As a result, the discharge portion 62d of the annular container 62 is positioned at a communication position where it communicates with the scrap receiving portion 63a of the drain means 63, as shown in Fig. 6. Then, by operating the positioning means 61, the scrap catcher 6 is raised in the direction indicated by the arrow R2 in the figure to its operating position, and the upper end portion 6b of the scrap catcher 6 is positioned at a height position above the top surfaces of the stacked wafers W held on the chuck table 5, i.e., above the top surface of the first wafer 10A (see also Fig. 5). In the grinding device 1 of this embodiment, the drain means 63 is disposed only at a position corresponding to the first grinding region B, and the discharge portion 62d of the annular container 62 is connected to the scrap receiving portion 63a of the drain means 63 only in the first grinding region B. That is, by rotating the turntable 2d, the discharge portion 62d of the annular container 62 is switched to a non-communicating position that does not connect to the scrap receiving portion 63a of the drain means 63 in the other regions, i.e., the carry-in region A, the second grinding region C, and the carry-out region D.

[0049] Next, by rotating the chuck table 5 positioned in the first grinding region B, the stacked wafers W are rotated in the direction indicated by arrow R6 in FIG. 6 at a predetermined rotational speed (e.g., 300 rpm), and the grinding wheel 34 of the first grinding means 3 is rotated in the direction indicated by arrow R7 in the figure at a predetermined rotational speed (e.g., 6000 rpm). Next, the grinding feed means 38 is operated to lower the first grinding means 3 downward in the direction indicated by arrow R8, bringing the grinding wheel 35 into contact with the stacked wafers W, and grinding is fed at a predetermined grinding feed rate (e.g., 1.0 μm / sec), thereby performing rough grinding until the stacked wafers W reach a desired thickness. This rough grinding can be performed while detecting the thickness of the stacked wafers W using a non-contact thickness detection means (not shown). At this time, the grinding water supply means 49 is operated to supply grinding water L to the grinding location where the stacked wafers W come into contact with the grinding wheel 35. The above-mentioned recesses 6e are formed in two locations on the upper end 6b of the scrap catcher 6, and are formed to allow the grinding wheel 35 disposed on the grinding wheel 34 to pass through. The bottoms 6f of the recesses 6e are set to be lower than the upper surfaces of the stacked wafers W, thereby preventing the grinding wheel 35 from interfering with the scrap catcher 6 when the above-mentioned rough grinding process is performed.

[0050] As explained with reference to Fig. 2, an annular modified layer 100 is formed on the first wafer 10A of the stacked wafers W along the entire periphery of the chamfered portion 12A of the first wafer 10A, and serves as a separation starting point for separating the chamfered portion 12A. As a result, in the process of performing the rough grinding process described above to grind the first wafer 10A to a desired thickness, the chamfered portion 12A formed on the outer periphery of the first wafer 10A becomes scrap 12A and is separated from the first wafer 10A, as shown in Fig. 6. The scrap 12A separated from the first wafer 10A of the stacked wafers W is scattered and captured inside the scrap capture body 6, and falls into the annular container 62 along the ring guide 64 described above (see also Fig. 5).

[0051] The scraps 12A are discharged into the annular container 62 together with the grinding water L, and the scraps 12A are flowed to the discharge section 62d side of the annular container 62 together with the grinding water L. At this time, water (which also serves as the grinding water L) is sprayed from the spray holes 66a of the scrap nozzle 66 in the annular container 62, so that the scraps 12A discharged into the annular container 62 are swept toward the discharge section 62d side. This prevents the scraps 12A from accumulating inside the annular container 62.

[0052] As shown in Fig. 6, the scrap 12A discharged to the discharge port 62d of the annular container 62 is guided together with grinding water L to the scrap receiving port 63a formed at the upper end of the drain means 63. At this time, the selector 65 closes the second drain 63d side of the switching valve 65a, so the grinding water L and the scrap 12A guided to the scrap receiving port 63a flow from the main drain 63b to the first drain 63c. The scrap 12A is then collected in the scrap receiving means 70A attached to the lower end 63e of the first drain 63c, and the grinding water L is discharged from the drain hole 74A formed at the lower end of the cup-shaped member 72A constituting the scrap receiving means 70A, drained into the drain container 68, and then discharged to the outside through the waste drain 68a.

[0053] The drain means 63 described above is provided with a first drain 63c and a second drain 63d that can be switched by the selection unit 65, and is configured so that the scrap storage means 70A, 70B can be removed and attached to each of them using the above-mentioned procedure. Therefore, if the scrap storage means 70B is attached to the second drain 63d side in advance, even if the scrap storage means 70A attached to the first drain 63c side becomes full, the selection unit 65 can switch the flow of grinding water L and scrap 12A to the second drain 63d side, and while the scrap storage means 70B continues to collect the scrap 12A, the scrap storage means 70A can be removed and the scrap 12A can be disposed of using the above-mentioned procedure.

[0054] Once the rough grinding in the first grinding region B is completed and the chamfered portions 12A of the first wafers 10A constituting the stacked wafers W are separated and removed, the turntable 2d is rotated 90° in the direction indicated by the arrow R1, and the chuck table 5, which has completed the rough grinding of the stacked wafers W, is moved from the first grinding region B to the second grinding region C. At this time, the chuck table 5 moved from the loading region A to the first grinding region B holds the unprocessed stacked wafers W, and the unprocessed stacked wafers W are positioned in the first grinding region B. Then, once the chuck table 5 is positioned in the second grinding region C, the chuck table 5 is rotated at the predetermined rotational speed (e.g., 300 rpm) to rotate the stacked wafers W held on the chuck table 5, and the rotary shaft 42 of the second grinding means 4 is rotated at a predetermined rotational speed (e.g., 6000 rpm). At this time, by operating the positioning means 61 described above, the scrap capture body 6 is moved to a non-operating position (see also Figure 4(b)), and the upper end portion 6b of the scrap capture body 6 is moved to a position lower than the upper surface of the first wafer 10A of the stacked wafers W held on the chuck table 5.

[0055] Next, the grinding feed means 48 is operated to lower the second grinding means 4, and the grinding wheel 45 of the second grinding means 4 is brought into contact with the stacked wafers W. While the grinding water supply means 49 supplies grinding water L to the grinding location, the grinding feed is performed at a predetermined grinding feed rate (e.g., 0.05 μm / sec). The first wafer 10 is then finished to a desired thickness by the grinding wheel 45. This finish grinding can be performed while detecting the thickness of the stacked wafers W using a non-contact thickness detection means (not shown). While the finish grinding is being performed in the second grinding region C, the rough grinding process for removing the chamfered portion 12A of the first wafer 10A is simultaneously performed in the first grinding region B. The unprocessed stacked wafers W are transferred from the first cassette 7a to the chuck table 5 positioned in the loading region A, where they are suction-held.

[0056] Once the finish grinding and the rough grinding performed simultaneously are completed, the turntable 2d is rotated 90° in the direction indicated by the arrow R1, and the chuck table 5 holding the stacked wafers W that have undergone finish grinding is moved to the unloading area D. At the same time, the chuck table 5 moving from the first grinding area B to the second grinding area C holds the stacked wafers W from which the first wafer 10A has been rough ground and the chamfered portion 12A has been separated and removed from the outer periphery as scrap material. The chuck table 5 moving from the loading area A to the first grinding area B holds the unprocessed stacked wafers W. Then, once the chuck table 5 holding the stacked wafers W that have undergone finish grinding is positioned in the unloading area D, the third transport means 11C sucks the stacked wafers W and transports them to the cleaning means 9 for cleaning and drying. Even at this time, the scrap capture body 6 remains positioned in the inactive position. Thereafter, the stacked wafers W cleaned and dried in the cleaning means 9 are transported and stored in the second cassette 7b by the first transport means 11A. By repeating the above-described procedure, the above-described grinding process is performed on all of the stacked wafers W stored in the first cassette 7a.

[0057] According to the above-described embodiment, even if the chamfered portion 12A falls off as scrap from the stacked wafers W when rough grinding is performed, it is collected by the scrap collection means 60, thereby eliminating the problem that scrap accumulates in the drain pan 2e of the grinding device 1, which requires frequent cleaning and is an unbearable hassle.

[0058] In the above-described embodiment, the workpiece ground by the grinding apparatus 1 is the stacked wafer W shown in Fig. 2(a), but the present invention is not limited to this, and the workpiece may be a single wafer 10C having an outer peripheral excess region 18C corresponding to the chamfered portion 17C on the front surface 10Ca that has been edge-trimmed to remove a portion of the chamfered portion 17C to a depth equivalent to the finishing thickness, as shown in Fig. 2(b). Even in this case, the chamfered portion 17C is separated and removed in the process of rough grinding the back surface 10Cb, and is collected by the scrap collecting means 60, so that the same effects as those of the above-described embodiment can be achieved.

[0059] In the above embodiment, the present invention is applied to a grinding apparatus 1 having four chuck tables 5 arranged on the turntable 2d, but the present invention is not limited to this and may be applied to a grinding apparatus having only one chuck table. However, by arranging two or more chuck tables on the turntable and configuring the turntable to rotate as described above to switch between a communication position in which the discharge portion of the annular container communicates with the scrap receiving portion of the scrap collecting means and a non-communication position in which the discharge portion does not communicate with the scrap receiving portion of the scrap collecting means, it becomes possible to simultaneously and continuously perform rough grinding, which collects scraps that fall off the outer periphery of the wafer, and finish grinding, thereby enabling efficient grinding of the wafer. [Explanation of symbols]

[0060] 1: Grinding device 2: Device housing 2a: Support wall 2b, 2c: Guide rails 2d: Turntable 2e: Drain pan 2f: Drain port 3: First grinding method 31: Unit housing 32: Rotation axis 33: Wheel mount 34: Grinding wheel 35: Grinding wheel 36: Electric motor 37: Mobile base 38: Grinding feed means 4: Second grinding method 41: Unit housing 42: Rotation axis 43: Wheel mount 44: Grinding wheel 45: Grinding wheel 46: Electric motor 47: Mobile base 48: Grinding feed means 5: Chuck table 6: Scrap wood capture body 6a: opening 6b: Upper end 6c: Side wall part 6d: Connecting part 6e: recess 6f: bottom 7a: First cassette 7b: Second cassette 8: Alignment means 9: Cleaning method 11A: First conveying means 11B: Second conveying means 11C: Third transport means 20: Control means 60: Scrap material collection method 61: Positioning means 62: Annular container 62a: Inner wall 62b:Outer wall 62c: Bottom wall 62d: Discharge section 62e: Nozzle hole 66: Scrap material nozzle 66a: Injection hole 67: Rotating plate 68: Drainage container 70A, 70B: scrap material storage means 100: Modified layer A: Delivery area B: First grinding zone C: Second grinding zone D: Export area

Claims

1. A grinding apparatus for grinding a surface of a wafer, comprising: The apparatus includes a rotatable chuck table for holding a wafer, and a grinding means having a rotatable grinding wheel having an annularly arranged grinding stone for grinding a surface of the wafer held on the chuck table while supplying grinding water thereto, a scrap catcher disposed around the chuck table for capturing scraps that fall off from the outer periphery of the wafer during grinding, a positioning means for positioning the scrap catcher at an operating position and a non-operating position, and a scrap collecting means for collecting the scraps captured by the scrap catcher, A recess is formed at the upper end of the scrap catcher to allow the grinding wheel attached to the grinding wheel to pass through, and when the scrap catcher is positioned in the operating position by the positioning means, the upper end of the scrap catcher is positioned at a position above the upper surface of the wafer held on the chuck table, and the bottom of the recess is positioned below the surface of the wafer held on the chuck table to avoid contact with the grinding wheel, thereby grinding the wafer held on the chuck table.

2. The scrap recovery means includes: an annular container including an annular inner wall surrounding the chuck table, an annular outer wall, a bottom wall connecting the inner wall and the outer wall, and a discharge portion for discharging scrap materials; 2. The grinding apparatus as described in claim 1, comprising: an annular ring guide arranged on the chuck table for guiding scrap material falling off from the outer periphery of the wafer to the annular container; a drain means having a scrap material receiving portion communicating with a discharge portion of the annular container; and a scrap material storage means arranged at the other end of the drain means.

3. 3. The grinding apparatus according to claim 2, wherein said drain means comprises a main drain, a first drain and a second drain branched off from said main drain, and a selection portion for selecting between said first drain and said second drain.

4. 4. The grinding apparatus according to claim 3, wherein the chuck table is disposed on a drain pan for receiving grinding water, the drain pan having a drain outlet and a drain drain communicating with the drain outlet, and an end of the drain drain is connected to the main drain.

5. 3. The grinding apparatus of claim 2, wherein the annular vessel includes a scrap nozzle for supplying water to sweep the scrap into the discharge area.

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