Grinding device and maintenance method of the same

Abstract

To provide a grinding device which enables reduction of the frequency of flattening work for grinding a holding surface of a chuck table with a grinding wheel and improves of the operation rate of the grinding device.SOLUTION: A grinding device includes: a chuck table 6 which suctions and holds a wafer; grinding means in which a grinding wheel, including grind stones for grinding the wafer held by the chuck table 6 which are arranged in an annular form, is attached in a rotatable manner; and grinding water supply means which supplies grinding water to a contact area between the wafer held by the chuck table 6 and the grinding stones. The chuck table 6 is formed including: a porous plate 6a having a holding surface for suctioning and holding the wafer; a frame body 6b which encloses the holding surface of the porous plate 6a; suction means 80 which communicates with the frame body 6b and generates suction force on the holding surface of the porous plate 6a; and fluid supply means 70 which communicates with the frame body 6b and jets a fluid to the holding surface of the porous plate 6a. The fluid supply means 70 jets a cleaning liquid G, containing a surface active agent or a dispersant or the surface active agent and the dispersant, from the holding surface of the porous plate 6a.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a grinding apparatus for grinding wafers and a maintenance method for the grinding apparatus. [Background technology]

[0002] A wafer has a plurality of devices such as ICs and LSIs formed on its surface, separated by planned dividing lines. The back surface is ground by a grinding machine to form the wafer to a specified thickness, and then the wafer is divided into individual device chips by a dicing machine, which are then used in electrical devices such as mobile phones and personal computers.

[0003] The grinding device is configured to include a chuck table that suction-holds the wafer, a grinding means having a rotatably mounted grinding wheel with a ring-shaped arrangement of grinding stones that grind the wafer held on the chuck table, and a grinding water supply means that supplies grinding water to the contact area between the wafer held on the chuck table and the grinding stones, and can process the wafer to the desired thickness with high precision.

[0004] Furthermore, the holding surface of the chuck table that holds the wafer sucks in grinding water mixed with grinding debris, which contaminates the holding surface and reduces suction power. In addition, the sucked in grinding debris creates unevenness on the holding surface, making it impossible to process the wafer thickness with high precision. Therefore, as necessary, the holding surface of the chuck table is ground and flattened with a grinding wheel (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-114336 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the planarization process of grinding and flattening the holding surface of the chuck table takes a long time (e.g., half a day to a day), and the operation of the grinding device must be stopped while the planarization process is being carried out, which reduces the operating rate of the grinding device and reduces productivity.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and its main technical object is to provide a grinding device and a maintenance method for a grinding device that can reduce the frequency of flattening work in which the holding surface of the chuck table is ground with a grinding wheel, thereby improving the operating rate of the grinding device. [Means for solving the problem]

[0008] In order to solve the above-mentioned main technical problems, according to the present invention, there is provided a grinding apparatus for grinding wafers, comprising: a chuck table for suction-holding a wafer; grinding means having a rotatably mounted grinding wheel with a ring-shaped arrangement of grinding stones for grinding the wafer held on the chuck table; and grinding water supply means for supplying grinding water to the contact area between the wafer held on the chuck table and the grinding stones, wherein the chuck table comprises a porous plate having a holding surface for suction-holding the wafer, a frame surrounding the holding surface of the porous plate, suction means connected to the frame and generating a suction force on the holding surface of the porous plate, and fluid supply means connected to the frame and spraying a fluid onto the holding surface of the porous plate, and the fluid supply means sprays a cleaning liquid containing either a surfactant or a dispersant, or a surfactant and a dispersant, from the holding surface of the porous plate.

[0009] The fluid supply means preferably includes a water source that supplies water and sprays it from the holding surface of the porous plate, and the cleaning liquid is mixed in the water supplied from the water source. The fluid supply means preferably includes a water source that supplies water, a cleaning liquid source that supplies the cleaning liquid, and a mixer that mixes the water supplied from the water source with the cleaning liquid supplied from the cleaning liquid source. Furthermore, the fluid supply means may include an air supply source, and may spray air alone onto the holding surface of the porous plate, or may mix the air with another fluid that can be supplied from the fluid supply means and spray it from the holding surface of the porous plate.

[0010] Further, according to the present invention, there is provided a maintenance method for a grinding device including a chuck table for suction-holding a wafer, grinding means having a grinding wheel rotatably mounted thereon, the grinding wheel having annularly arranged grinding stones for grinding the wafer held on the chuck table, and grinding water supply means for supplying grinding water to a contact area between the wafer held on the chuck table and the grinding stones, wherein the chuck table includes a porous plate having a holding surface for suction-holding the wafer, a frame surrounding the porous plate except for the holding surface, suction means communicating with the frame and generating a suction force on the holding surface of the porous plate, and a suction means communicating with the frame; A maintenance method for a grinding device is provided, which includes a fluid supply means for spraying a fluid onto the holding surface of the porous plate, a holding step in which a wafer is placed on the holding surface of the chuck table and the suction means is operated to hold the wafer, a grinding step in which grinding water is supplied to the contact area between the wafer held on the chuck table and the grinding wheel to grind the wafer, and a cleaning step in which, after the grinding step is completed, the fluid supply means is operated to spray a cleaning liquid containing either a surfactant or a dispersant, or a surfactant and a dispersant, onto the holding surface of the porous plate to clean it and remove grinding debris from the porous plate. [Effects of the Invention]

[0011] The grinding apparatus of the present invention is a grinding apparatus for grinding wafers, and includes a chuck table for suction-holding a wafer, grinding means having a grinding wheel rotatably mounted thereon, the grinding wheel having grinding stones arranged in an annular shape for grinding the wafer held on the chuck table, and grinding water supply means for supplying grinding water to a contact area between the wafer held on the chuck table and the grinding stones, wherein the chuck table includes a porous plate having a holding surface for suction-holding the wafer, a frame surrounding the holding surface of the porous plate, and suction means communicating with the frame and generating a suction force on the holding surface of the porous plate; and a fluid supply means connected to the frame body for spraying a fluid onto the holding surface of the porous plate. The fluid supply means sprays a cleaning liquid containing either a surfactant or a dispersant, or a surfactant and a dispersant, onto the holding surface of the porous plate. Therefore, even if the holding surface of the porous plate of the chuck table has been contaminated by sucking in grinding water containing grinding chips, the action of the cleaning liquid can effectively remove the grinding chips from the holding surface, reducing the frequency with which the holding surface of the chuck table needs to be ground and flattened with a grinding wheel and improving the operating rate of the grinding device.

[0012] The present invention also provides a maintenance method for a grinding device comprising a chuck table for suction-holding a wafer, grinding means having a grinding wheel rotatably mounted thereon, the grinding wheel having annularly arranged grinding stones for grinding the wafer held on the chuck table, and grinding water supply means for supplying grinding water to a contact area between the wafer held on the chuck table and the grinding stones, wherein the chuck table comprises a porous plate having a holding surface for suction-holding the wafer, a frame surrounding the porous plate except for the holding surface, suction means communicating with the frame and generating a suction force on the holding surface of the porous plate, and fluid supply means communicating with the frame for spraying a fluid on the holding surface of the porous plate, and the chuck table is provided with ... a suction means communicating with the frame and generating a suction force on the holding surface of the porous plate, and a fluid supply means for supplying a fluid to the holding surface of the porous plate. The method includes a holding step of operating a stage to hold the wafer, a grinding step of supplying grinding water to the contact area between the wafer held on the chuck table and the grinding wheel to grind the wafer, and a cleaning step of operating the fluid supply means after the grinding step is completed to spray a cleaning liquid containing either a surfactant or a dispersant, or a surfactant and a dispersant, onto the holding surface of the porous plate to clean it and remove grinding debris from the porous plate.Therefore, even if the holding surface of the porous plate on the chuck table has been contaminated by sucking in grinding water containing grinding debris, the action of the cleaning liquid can effectively remove the grinding debris from the holding surface, reducing the frequency at which the holding surface of the chuck table needs to be ground and flattened by a grinding wheel, thereby improving the operating rate of the grinding device. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is an overall perspective view of the grinding device. [Figure 2] 3A and 3B are a partially enlarged cross-sectional view of a chuck table and a block diagram showing the configuration of a fluid supply means; [Figure 3] FIG. 2 is a perspective view of a wafer to be processed by the grinding apparatus of FIG. [Figure 4] FIG. 10 is a perspective view showing an embodiment of a holding step in the maintenance method for the grinding device of the present embodiment. [Figure 5] FIG. 1 is a perspective view showing an embodiment of rough grinding. [Figure 6] FIG. 1 is a perspective view showing an embodiment of a cleaning step. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a grinding device and a maintenance method for a grinding device configured based on the present invention will be described in detail with reference to the accompanying drawings.

[0015] FIG. 1 shows a grinding device 1 of this embodiment. The illustrated grinding apparatus 1 includes a chuck table 6 that suction-holds the wafer W, grinding means 3 and 4 on which grinding wheels having grinding stones arranged in a ring shape for grinding the wafer W held on the chuck table 6 are rotatably mounted, and a grinding water supply means 10 equipped with a grinding water source S1 that supplies grinding water L to the contact area between the wafer W held on the chuck table 6 and the grinding stones arranged on the grinding means 3 and 4.The chuck table 6 includes a porous plate 6a with air permeability and having a holding surface that suction-holds the wafer W, a frame 6b that surrounds the holding surface of the porous plate 6a, a fluid supply means 70 (see Figure 2, described later) that communicates with the frame 6b and sprays a fluid onto the holding surface of the porous plate 6a, and a suction means 80 (see Figure 2, described later) that communicates with the frame 6b and generates a suction force on the holding surface of the porous plate 6a. The grinding device 1 of this embodiment will be described in more detail below.

[0016] The illustrated grinding apparatus 1 includes a substantially rectangular parallelepiped apparatus housing 2. A support wall 21 is erected on the rear end side of the illustrated apparatus 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 this support wall 21. A rough grinding unit 3 serving 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 serving as finish grinding means is mounted on the other guide rails 23, 23 so as to be movable in the vertical direction.

[0017] The rough grinding unit 3 includes a unit housing 31, a wheel mount 33 disposed at the lower end of a rotating shaft 32 rotatably supported by the unit housing 31, a rough grinding wheel 34 mounted on the wheel mount 33 and having a plurality of grinding wheels 35 arranged in an annular pattern on its underside, an electric motor 36 mounted at the upper end of the unit housing 31 for 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. A grinding water source S1 constituting a grinding water supply means 10 for supplying grinding water L is connected to the upper end 32a of the rotating shaft 32, and grinding water L is introduced from the upper end 32a by opening an on-off valve V1 of a path P1. The grinding water L introduced via the rotating shaft 32 is supplied to the underside of the rough grinding wheel 34 and then to the contact area between the wafer W held on the chuck table 6 and the grinding wheels 35.

[0018] The movable base 38 is provided with guided grooves that slidably engage with the guide rails 22, 22 provided on the support wall 21, and the rough grinding unit 3 is supported so as to be movable in the vertical direction. The illustrated grinding apparatus 1 is equipped with a grinding feed mechanism 39 that raises and lowers the movable base 38 of the rough grinding unit 3 along the guide rails 22, 22. The grinding feed mechanism 39 is equipped with an externally threaded rod 391 that is rotatably supported and disposed in the vertical direction on the support wall 21 parallel to the guide rails 22, 22, a pulse motor 392 for driving the rotation of the externally threaded rod 391, and an internally threaded block (not shown) that is attached to the movable base 38 and threadably engages with the externally threaded rod 391, and the rough grinding unit 3 is moved in the vertical direction by driving the externally threaded rod 391 in the forward and reverse directions by the pulse motor 392.

[0019] The finish grinding unit 4 is configured substantially similarly to 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 by the unit housing 41, a finish grinding wheel 44 mounted on the wheel mount 43 and having a plurality of grinding wheels 45 arranged in an annular pattern on its underside, an electric motor 46 mounted at 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. A grinding water source S1 constituting the grinding water supply means 10 for supplying grinding water L is connected to the upper end 42a of the rotating shaft 42, and grinding water L is introduced from the upper end 42a by opening an on-off valve V2 of the path P1. The grinding water L introduced via the rotating shaft 42 is supplied to the underside of the finish grinding wheel 44 and then to the contact area between the wafer W held on the chuck table 6 and the grinding wheels 45.

[0020] The movable base 48 is provided with guided grooves that slidably engage with the guide rails 23, 23 provided on the support wall 21, and the finish grinding unit 4 is supported so as to be movable in the vertical direction. The grinding apparatus 1 is provided with a grinding feed mechanism 49 as 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 provided with an externally threaded rod 491 that is rotatably supported and disposed in the vertical direction on the support wall 21 parallel to the guide rails 23, 23, a pulse motor 492 for driving the rotation of the externally threaded rod 491, and an internally threaded block (not shown) that is attached to the movable base 48 and threadably engages with the externally threaded rod 491, and the externally threaded rod 491 is driven to rotate forward and backward by the pulse motor 492, thereby moving the finish grinding unit 4 in the vertical direction.

[0021] The grinding machine 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 housing 2. The turntable 5 is formed in a relatively large disk shape and is rotated in the direction indicated by the arrow R3 by a rotation drive mechanism (not shown) within a drain pan 20 on the upper surface of the housing 2. The turntable 5 is provided with three chuck tables 6, each of which serves as a holding means for holding a workpiece at a 120-degree angle. Each chuck table 6 is equipped with a rotation drive means 60 (see FIG. 2, described later) and is configured to rotate in the direction indicated by the arrow R4. The chuck table 6 is formed in a disk shape by a porous plate 6a with air permeability and a frame 6b surrounding the porous plate 6a. The frame 6b is connected to a fluid supply means 70 and a suction means 80 (described later) (see FIG. 2, described later).

[0022] 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 16 is arranged near the workpiece carry-in / out area A in the drain pan 20, for supplying cleaning water L (which can also be used as the grinding water L) to the upper surface of the chuck table 6 positioned in the workpiece carry-in / out area A.

[0023] The grinding device 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 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 on which the wafers W are temporarily placed and centered, cleaning means 11 disposed between the workpiece carry-in / out area A and the second cassette 8 for cleaning the ground surface of the wafer W, and a cleaning device 12 for cleaning the wafers W stored in the first cassette 7 and carrying out the wafers W to the temporary placement table 9. Also provided are workpiece carry-in / out means 13 for carrying the wafer W cleaned by the cleaning means 11 into the second cassette 8, carry-in means 14 for carrying the wafer W held on the temporary storage table 9 into the chuck table 6 positioned in the workpiece carry-in / out area A, carry-out means 15 for carrying the ground wafer W held on the chuck table 6 positioned in the workpiece carry-in / out area A out to the cleaning means 11, and a cleaning water supply nozzle 16 for supplying cleaning water L (which can also serve as the grinding water L) to the upper surface of the chuck table 6 positioned in the workpiece carry-in / out area A. Note that the carry-in means 14 and carry-out means 15 are not necessarily limited to being disposed separately, and for example, the carry-out means 15 alone may be disposed behind the cleaning water supply nozzle 16 so as to also serve as the carry-in means 14.

[0024] The carry-in means 14 is capable of moving up and down in the vertical direction (Z-axis direction), and includes an arm member 141 that pivots between the temporary placement table 9 and the workpiece carry-in / carry-out position A, and a suction unit 142 that is formed at the tip of the arm member 141 and has a suction hole on the underside to generate suction force. The carry-out means 15 is capable of moving up and down in the vertical direction (Z-axis direction), and includes an arm member 151 that pivots between the workpiece carry-in / carry-out position A and the cleaning means 11, and a suction unit 152 that is formed at the tip of the arm member 151 and has a suction hole on the underside to generate suction force.

[0025] The grinding apparatus 1 is equipped with a control means (not shown). The control means is configured by a computer and includes 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 temporarily stores detected values, calculation results, etc., an input interface, and an output interface (details not shown). The control means is connected to each operating unit of the grinding apparatus 1 described above, and the control means controls each operating unit to perform the grinding process and a maintenance method for the grinding apparatus 1, which will be described later.

[0026] 2 shows the chuck table 6, and a fluid supply means 70 and a suction means 80 connected to the chuck table 6. As described above, the chuck table 6 includes a frame 6b surrounding the porous plate 6a, a rotation shaft 6c formed integrally with the frame 6b, a driven pulley 6d disposed on the rotation shaft 6c, and a rotation drive means 60 that rotates the chuck table 6. The rotation drive means 60 includes a drive motor 61 and a drive pulley 62 driven by the drive motor 61, and a belt 63 is wound around the driven pulley 6d and the drive pulley 62. By rotating the drive motor 61, a driving force is transmitted via the belt 63, and the chuck table 6 is rotated in the direction indicated by the arrow R4 in FIG. 1.

[0027] A fluid supply means 70 and a suction means 80 are connected to a communication passage 6e formed inside the rotating shaft 6c that constitutes the frame 6b of the chuck table 6. The suction means 80 includes a suction source S2 and a path P2 equipped with an on-off valve V3, and by operating the suction source S2 and opening the on-off valve V3, a suction force can be generated on the holding surface of the porous plate 6a via the communication passage 6e formed in the rotating shaft 6c.

[0028] The fluid supply means 70 has a function of spraying cleaning liquid G containing at least a surfactant, a dispersant, or both a surfactant and a dispersant from the holding surface of the porous plate 6a that constitutes the chuck table 6. The illustrated fluid supply means 70 is provided with a cleaning liquid source S3 that supplies cleaning liquid G and a path P3 equipped with an on-off valve V4, and the cleaning liquid G is supplied to the communication path 6e of the rotation shaft 6c of the chuck table 6 via a first connecting portion 64a of a rotary joint 64. When the fluid supply means 70 supplies fluid to the chuck table 6, the on-off valve V3 on the path P3 is closed and the operation of the suction means 80 is stopped.

[0029] The cleaning liquid G supplied by the cleaning liquid source S3 is a liquid containing either a surfactant or a dispersant, or a surfactant and a dispersant, and is composed of, for example, the components shown below.

[0030] Examples of surfactants contained in the cleaning solution G include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.

[0031] Examples of nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyalkylene alkylamines, and sorbitan fatty acid esters.

[0032] Examples of anionic surfactants include polyoxyethylene alkyl ether sulfates, alkylbenzene sulfonates, alkyl ether sulfates, alkenyl succinates, alkyl naphthalene sulfonates, alkyl sulfates, alkyl phosphates, polycarboxylic acid ethers, polycarboxylic acid salts, and sulfates.

[0033] Examples of cationic surfactants include alkyltrimethylammonium sulfate and alkyldimethylbenzylammonium sulfate.

[0034] Examples of amphoteric surfactants include alkyl betaines and amido betaines.

[0035] Examples of dispersants contained in the cleaning solution G include polyacrylic acid and its salts, polyacrylic acid maleate copolymers, olefin maleate copolymers, polyalkylene glycols, cellulose, hydroxyalkyl celluloses, carboxyalkyl celluloses, hexametaphosphates, lignin sulfonates, alkyl phenyl ether sulfates, polyvinyl alcohols, polyvinylpyrrolidone, polyvinyl acetate, and polyoxyethylene polyoxypropylene glycol ethers. When the cleaning solution G contains a dispersant, it is preferable that the molecular weight of the dispersant be 12,000 or less.

[0036] The illustrated fluid supply means 70 includes, in addition to the cleaning liquid source S3, a water source S4 that supplies water H (e.g., pure water) and sprays it from the holding surface of the porous plate 6a of the chuck table 6. A path P4 equipped with an on-off valve V5 supplies the water H from the water source S4 to the second connecting portion 64b of the rotary joint 64. A path P6 equipped with an on-off valve V6 branches off from the path P4 and is connected to the path P3. A mixer 72 is provided at the junction connecting the path P6 to the path P3, mixing the cleaning liquid G supplied from the cleaning liquid source S3 with the water H supplied from the water source S4. The water source S4 can also serve as the grinding water source S1, and grinding water L may be supplied as the water H.

[0037] The illustrated fluid supply means 70 further includes an air supply source S5 and a path P5 equipped with an on-off valve V9 that connects air J supplied from the air supply source S5 to the third connecting portion 64c of the rotary joint 64. Also included are a path P7 branching from the path P5 and equipped with an on-off valve V7 that connects to the path P3, and a path P8 branching from the path P5 and equipped with an on-off valve V8 that connects to the path P4. A mixer 74 that mixes cleaning liquid G supplied from the cleaning liquid source S3 with air J supplied from the air source S5 is provided at the point where the path P7 connects to the path P3. A mixer 76 that mixes water H supplied from the water source S4 with air J supplied from the air source S5 is provided at the point where the path P4 connects to the path P8. In FIG. 2, paths P3 to P5 that communicate with the rotary joint 64 of the chuck table 6 are collectively referred to as a supply path P0.

[0038] The fluid supply means 70 has the above-described configuration, and is therefore able to eject the fluid onto the holding surface of the porous plate 6a as follows.

[0039] When the fluid supply means 70 is used to spray cleaning liquid G from the porous plate 6a of the chuck table 6, the on-off valve V4 of the path P3 is opened, and the other on-off valves V5 to V9 are closed. This allows cleaning liquid G to be supplied to the first connecting portion 64a of the rotary joint 64 via the path P3, and then sprayed onto the holding surface of the porous plate 6a via the connecting passage 6e of the rotating shaft 6c. Furthermore, the on-off valves V4 and V6 are opened, and the other on-off valves V5, V7 to V9 are closed. This allows cleaning liquid G to be mixed with water H supplied from the water source S4 in the mixer 72, and then supplied to the first connecting portion 64a of the rotary joint 64 via the path P3. The mixed fluid of water H and cleaning liquid G can then be sprayed onto the holding surface of the porous plate 6a via the connecting passage 6e of the rotating shaft 6c. In particular, by controlling the opening of on-off valve V6, it is possible to change the amount of water H supplied and adjust the concentration of the cleaning solution G, thereby achieving a desired concentration according to the surfactant and dispersant selected for the cleaning solution G. Furthermore, by opening only on-off valve V5 and closing the other on-off valves V4, V6 to V9, only water H is supplied to the second connecting portion 64b of the rotary joint 64 via path P4, and water H can be sprayed alone onto the holding surface of the porous plate 6a via the communicating passage 6e of the rotary shaft 6c.

[0040] Air J supplied from the air supply source S5 can be mixed with another fluid, such as cleaning liquid G, that can be supplied from the fluid supply means 70, and sprayed from the holding surface of the porous plate 6a of the chuck table 6. In this case, on-off valves V4 and V7 are opened, and the other on-off valves V5, V6, V8, and V9 are closed. In this manner, air J is mixed with cleaning liquid G in a bubbly state in the mixer 74, and the resulting mixture is supplied to the first connecting portion 64a of the rotary joint 64 via path P3. The resulting mixture, consisting of cleaning liquid G and air J in a bubbly state, can be sprayed onto the holding surface of the porous plate 6a via the communication passage 6e of the rotary shaft 6c. In particular, controlling the aperture of on-off valve V7 allows the amount of air J supplied to be changed, thereby adjusting the amount of air bubbles contained in cleaning liquid G.

[0041] Furthermore, by opening on-off valves V5 and V8 and closing the other on-off valves V4, V6, V7, and V9, air J supplied from air supply source S5 via path P8 and water H, another fluid that can be supplied from the fluid supply means 70, can be mixed and ejected from the holding surface of the porous plate 6a of the chuck table 6. In the mixer 76, the air J is mixed with the water H to form bubbles, and the mixture is supplied to the second connecting portion 64b of the rotary joint 64 via path P4. The mixed fluid, in which the air J is contained in the water H in a bubble state, can be ejected onto the holding surface of the porous plate 6a via the communicating passage 6e of the rotary shaft 6c. In particular, by controlling the aperture of on-off valve V8, the amount of air J mixed with the water H can be changed, thereby adjusting the amount of bubbles contained in the water H.

[0042] Furthermore, since the fluid supply means 70 has the above-described configuration, by opening only the on-off valve V9 and closing the other on-off valves V4 to V8, the air J alone is supplied to the third connecting portion 64c of the rotary joint 64 via the path P5, and the air J alone can be sprayed onto the holding surface of the porous plate 6a via the communication passage 6e of the rotating shaft 6c.

[0043] The fluid supply means 70 in the above-described embodiment includes a cleaning liquid source S3, a water source S4, and an air supply source S5, and forms a mixed fluid by mixing the cleaning liquid G supplied from the cleaning liquid source S3, the water H supplied from the water source S4, and the air J supplied from the air supply source S5, either singly or in an appropriate combination, and sprays the mixed fluid from the porous plate 6a of the chuck table 6. However, the present invention is not limited to this. For example, the fluid supply means 70 described with reference to FIG. 2 may be configured without the water source S4, without the air supply source S5, or without the water source S4 and the air supply source S5.

[0044] The grinding apparatus 1 of this embodiment has roughly the configuration described above, and the following describes the grinding process performed by the grinding apparatus 1 and the maintenance method of this embodiment performed on the grinding apparatus 1. In the following description, it is assumed that the fluid supply means 70 includes all of the cleaning liquid source S3, the water source S4, and the air supply source S5, as shown in FIG.

[0045] 3 shows a wafer W to be processed by the grinding apparatus 1. The wafer W is, for example, a silicon wafer, and a plurality of devices WD are formed on the front surface Wa, which is partitioned by planned division lines WL. A protective tape T is attached to the front surface Wa of the wafer W in advance as shown in the figure, and the wafer W is stored in the first cassette 7 with the back surface Wb, which is the grinding surface, facing upward.

[0046] When performing grinding using the grinding apparatus 1, first, the first cassette 7 containing a plurality of wafers W as described above is set in the grinding apparatus 1 shown in Fig. 1, and an empty second cassette 8 is also set. Next, the turntable 5 is operated to position the chuck table 6, which does not hold a wafer W, in the workpiece carry-in / out area A. Next, the workpiece carry-in / out means 13 is operated to carry out the unprocessed wafer W from the first cassette 7 and place it on the temporary placement table 9, where the centering of the wafer W is performed.

[0047] The wafer W, which has been centered by the temporary placement table 9, is sucked by the suction portion 142 of the carry-in means 14 and placed, with the protective tape T side facing downward, on the porous plate 6a that constitutes the holding surface of the chuck table 6 positioned in the workpiece carry-in / out area A, as shown in Fig. 4. Once the wafer W has been placed on the chuck table 6 in this manner, the on-off valve V3 of the suction means 80 is opened to generate a suction force on the holding surface of the porous plate 6a of the chuck table 6, thereby holding the wafer W (holding step).

[0048] After the holding step has been carried out as described above, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow R3 in FIG. 1, and the chuck table 6 supporting the unprocessed wafer W is moved toward the rough grinding area B.

[0049] Once the chuck table 6 holding the wafer W is positioned in the rough grinding area B, the rough grinding process described below is performed. More specifically, the rotation drive means 60 for driving the chuck table 6 is operated to rotate the chuck table 6 in the direction indicated by arrow R4 at, for example, 300 rpm, as shown in FIG. 5 . Next, the rough grinding unit 3 is operated to rotate the rough grinding wheel 34 in the direction indicated by arrow R1 in the figure at, for example, 6000 rpm. Then, the grinding feed mechanism 39 is operated to lower the rough grinding unit 3 in the direction indicated by arrow R5 in FIG. 5 , bringing the grinding wheel 35 into contact with the back surface Wb of the wafer W from above, and grinding is performed at a grinding feed rate of, for example, 1.0 μm / sec. At this time, the on-off valve V1 of the grinding water supply means 10 is opened to introduce grinding water L from the grinding water source S1 to the upper end 32a of the rotating shaft 32, and the grinding water L is supplied from the underside of the rough grinding wheel 34 toward the contact area between the back surface Wb of the wafer W and the grinding stone 35. At the same time, grinding can be carried out while measuring the thickness of the wafer W with a contact or non-contact measuring gauge (not shown), and the back surface Wb of the wafer W is roughly ground to a desired thickness for rough grinding, thereby completing the rough grinding process.

[0050] As described above, once the rough grinding is completed, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow R3, and the chuck table 6 holding the rough-ground wafer W is moved to the finish grinding area C, i.e., directly below the finish grinding unit 4. Once the chuck table 6 has been moved directly below the finish grinding unit 4, the rotary shaft 42 of the finish grinding unit 4 is rotated at, for example, 6000 rpm, while the chuck table 6 is rotated at, for example, 300 rpm. Note that the manner in which the finish grinding is performed is substantially the same as the rough grinding shown in FIG. 5 above, except that the grain size of the grinding wheel 45 is smaller than that of the grinding wheel 35 used in the rough grinding, and is therefore not shown in the figure. Then, the grinding wheel 45 is brought into contact with the back surface Wb of the wafer W, and the grinding wheel 44 is fed downward at a grinding feed rate of, for example, 0.1 μm / sec.

[0051] At this time, the on-off valve V2 of the grinding water supply means 10 is opened to introduce grinding water L from the upper end 42a of the rotating shaft 42, and the grinding water L is supplied from the underside of the finish grinding wheel 44 toward the contact area between the grinding stone 45 and the back surface Wb of the wafer W. At the same time, grinding can be carried out while measuring the thickness of the wafer W with a contact or non-contact measuring gauge (not shown), and the back surface Wb of the wafer W is ground to a desired thickness for finish grinding, thereby completing the finish grinding process, and the grinding step including the rough grinding and the finish grinding is completed. In the grinding apparatus 1 of this embodiment, after the finish grinding process is completed, the turntable 5 is rotated another 120 degrees in the direction indicated by R3, and the chuck table 6 holding the wafer W for which the grinding process has been completed is positioned in the workpiece loading / unloading area A, and cleaning water is sprayed from the cleaning water supply nozzle 16 toward the grinding surface of the wafer W for which the grinding process has been completed.

[0052] When the above-mentioned rough grinding process is performed, if a wafer W that has been subjected to the rough grinding process is positioned in the adjacent finish grinding area C, the above-mentioned finish grinding process can be performed simultaneously with the above-mentioned rough grinding process.

[0053] After the grinding process is completed, the cleaning process described below is carried out. In this embodiment, the cleaning process is carried out in a state where the wafer W that has been subjected to the grinding process is positioned in the workpiece loading / unloading area A.

[0054] When performing the cleaning process, the above-mentioned unloading means 15 is operated to rotate the arm member 151, and as shown in FIG. 6, the suction part 152 is positioned above the grinding surface (back surface Wb) of the wafer W positioned in the workpiece loading / unloading area A. Next, the unloading means 15 is lowered to abut against the back surface Wb, which is the grinding surface of the wafer W, and the suction means (not shown) is operated to generate a suction force on the lower surface side of the suction part 152, thereby suctioning the wafer W. Once the back surface Wb of the wafer W is suctioned by the suction part 152, the operation of the suction means 80 connected to the frame 6b of the chuck table 6 is stopped to release the suction force generated on the holding surface of the porous plate 6a of the chuck table 6, and the wafer W suctioned by the suction part 152 is slightly raised (for example, by 5 mm) above the holding surface of the chuck table 6.

[0055] Next, the fluid supply means 70 is operated to supply the cleaning liquid G (either a surfactant or a dispersant, or a surfactant and a dispersant) supplied from the cleaning liquid source S3 via the supply path P0, and perform a cleaning process in which the cleaning liquid G is sprayed onto the holding surface of the porous plate 6a of the chuck table 6. By performing the holding process, grinding process, and cleaning process as described above, the maintenance method for the grinding device of this embodiment is completed. Note that when performing this cleaning process, the cleaning liquid G and water H may be mixed and supplied.

[0056] For ease of explanation, Figure 2 shows only one chuck table 6, and also shows paths P3 to P8 for spraying cleaning liquid G, water H, and air J onto the holding surface of the porous plate 6a of the chuck table 6 shown, as well as a fluid supply means 70 including on-off valves V4 to V9 for selectively opening and closing the paths, and also shows a suction means 80 including path P2 and on-off valve V3 for generating a suction force on the holding surface of the porous plate 6a of the chuck table 6, and has been used to explain the holding process, grinding process, and cleaning process of this embodiment. However, as shown in FIG. 1, the grinding apparatus 1 of this embodiment is provided with three chuck tables 6, and each chuck table 6 is connected to a fluid supply means 70 and a suction means 80 shown in FIG. 2. Each of the three chuck tables 6 is provided with paths for spraying cleaning liquid G, water H, and air J, as described with reference to FIG. 2, and on-off valves for selectively opening and closing the paths, as well as paths and on-off valves for generating suction force. The above-mentioned control means independently controls the spraying of cleaning liquid G, water H, and air J by the fluid supply means 70, and the generation of suction force by the suction means 80.

[0057] According to the grinding apparatus 1 and the maintenance method for the grinding apparatus of this embodiment described above, even if the holding surface of the porous plate 6a of the chuck table 6 has been contaminated by sucking in grinding water containing grinding chips, the action of the cleaning liquid G described above can effectively remove the grinding chips from the holding surface, reducing the frequency with which the holding surface needs to be ground and flattened by a grinding wheel, thereby improving the operating rate of the grinding apparatus 1.

[0058] Furthermore, in the above-described cleaning step, when the cleaning liquid G is sprayed onto the holding surface of the porous plate 6a of the chuck table 6 to clean the holding surface, the wafer W is adsorbed by the adsorption section 152 of the carrying-out means 15 and positioned near the top of the holding surface. This allows the adsorption surface (protective tape T) of the wafer W adsorbed by the chuck table 6 to be cleaned simultaneously with the holding surface, thereby preventing the adsorption surface of the wafer W from becoming a source of contamination in the subsequent steps.

[0059] Furthermore, in the above-described cleaning step, when the cleaning liquid G is sprayed from the holding surface of the porous plate 6a, air J is supplied from the air supply source S5 of the fluid supply means 70 and mixed with the cleaning liquid G to form a mixed fluid in which the air J is contained in the cleaning liquid G in a bubble state, and this mixed fluid can be sprayed onto the holding surface of the porous plate 6a of the chuck table 6. In this way, the holding surface and the suction surface of the wafer W can be more effectively cleaned by the action of the air bubbles in addition to the action of the cleaning liquid G.

[0060] Furthermore, after the holding surface of the porous plate 6a and the suction surface of the wafer W are cleaned with the cleaning liquid G as described above, the supply of cleaning liquid G from the cleaning liquid source S3 is stopped, and water H is supplied to the chuck table 6 from the water source S4 of the fluid supply means 70 for a predetermined time. This allows the cleaning liquid G remaining on the holding surface and the suction surface of the wafer W to be washed away. When supplying water H to the chuck table 6 in this manner, air J may be mixed with the water H to form a mixed fluid containing air J in the form of bubbles in the water H, which is then sprayed from the holding surface. This allows the cleaning liquid G remaining on the holding surface and the suction surface of the wafer W to be more efficiently washed away by the action of the bubbles formed by the air J, thereby more reliably cleaning the holding surface and the suction surface of the wafer W.

[0061] As described above, the holding surface of the porous plate 6a of the chuck table 6 and the suction surface of the wafer W may be cleaned with the cleaning liquid G supplied from the cleaning liquid source S3, and the cleaning liquid G may be rinsed away with the water H supplied from the water source S4. Then, with the supply of the cleaning liquid G from the cleaning liquid source S3 and the supply of the water H from the water source S4 stopped, air J may be supplied alone to the chuck table 6 from the air supply source S5 of the fluid supply means 70 and sprayed from the holding surface. This blows away the water H remaining on the holding surface and the suction surface of the wafer W, allowing both to be quickly dried.

[0062] In the above-described embodiment, the wafer W is attracted by the suction portion 152 of the unloading means 15 and slightly elevated above the holding surface of the porous plate 6a of the chuck table 6, and the cleaning process is performed to clean the suction surface of the wafer W simultaneously with the holding surface. However, the present invention is not limited to this. For example, before the cleaning process is performed, the wafer W positioned in the workpiece loading / unloading area A may be unloaded by the unloading means 15, the wafer W may be transported to the cleaning means 11, and then the cleaning liquid G may be supplied to the chuck table 6 by the fluid supply means 70 and sprayed onto the holding surface of the porous plate 6a to clean only the holding surface. Even in such an embodiment, the action of the cleaning liquid G can effectively remove grinding debris from the holding surface, reducing the frequency with which the holding surface needs to be ground and flattened by a grinding wheel, thereby improving the operating rate of the grinding apparatus 1.

[0063] After the holding surface of the porous plate 6a of the chuck table 6 has been cleaned by the above-described cleaning step, the wafer W is unloaded by the unloading means 15 and transported to the cleaning means 11, which cleans the grinding surface (back surface Wb) of the wafer W. Then, after the grinding surface of the wafer W is cleaned and dried (details omitted) by the cleaning means 11, the wafer W is unloaded from the cleaning means 11 by the workpiece unloading means 13 and stored in a predetermined position in the second cassette 8, thereby completing the grinding process by the grinding device 1.

[0064] The grinding apparatus 1 of the above-described embodiment includes three chuck tables 6, a rough grinding unit 3, and a finish grinding unit 4. After rough grinding by the rough grinding unit 3, finish grinding by the finish grinding unit 4 is performed. However, the grinding apparatus of the present invention and the grinding apparatus to which the maintenance method of the present invention is applied are not limited to the above-described configuration and may include chuck tables other than three. For example, the grinding apparatus may include only one chuck table and perform only rough grinding, or may perform only finish grinding on wafers that have been rough ground by another grinding apparatus. It may also include four or more chuck tables. In any of the grinding apparatuses, as described above, a fluid supply means for supplying a cleaning liquid containing a surfactant, a dispersant, or both a surfactant and a dispersant can be provided. The cleaning liquid can be sprayed from the holding surface of the porous plate constituting the chuck table, thereby achieving the same effects as those of the above-described embodiment. [Explanation of symbols]

[0065] 1: Grinding device 2: Device housing 20: Drain pan 21:Supporting wall 22, 23: Guide rails 3: Rough grinding unit 31: Unit housing 32: Rotation axis 32a:Top end 33: Wheel mount 34: Rough 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 42a:Top end 43: Wheel mount 44: Finishing grinding wheel 45: Grinding wheel 46: Electric motor 47: Support member 48: Mobile base 49: Grinding feed mechanism 5: Turntable 6: Chuck table 6a: Porous plate 6b: Frame 6c: Rotation axis 6d: Pulley 6e: Communication path 7: First Cassette 8: Second cassette 9: Temporary table 10: Grinding water supply means 11: Cleaning method 13: Workpiece loading / unloading means 14: Means of transport 141: Arm member 142: Adsorption part 15: Export means 151: Arm member 152: Adsorption part 16: Cleaning water supply nozzle 60: Rotation drive means 61: Drive motor 62: Pulley 63: Belt 64: Rotary joint 64a: First connection part 64b:Second connection part 64c: Third connection part 70:Fluid supply means 72, 74, 76: Mixing section 80:Suction means S1: Grinding water source S2: Suction source S3: Cleaning fluid source S4: Water source S5: Air supply source V1 to V9: On-off valves P1~P8: Route

Claims

1. A grinding apparatus for grinding a wafer, a chuck table for suction-holding a wafer; and grinding means for grinding the wafer held on the chuck table, the grinding wheel having grinding stones arranged in an annular shape and rotatably mounted thereon. a grinding water supply means for supplying grinding water to a contact area between the wafer held on the chuck table and the grinding wheel, The chuck table is configured to include a porous plate having a holding surface that suction-holds a wafer, a frame that surrounds the holding surface of the porous plate, suction means that communicates with the frame and generates a suction force on the holding surface of the porous plate, and fluid supply means that communicates with the frame and sprays a fluid onto the holding surface of the porous plate, The fluid supplying means is a grinding apparatus that sprays a cleaning liquid containing either a surfactant or a dispersant, or a surfactant and a dispersant, from the holding surface of the porous plate.

2. 2. The grinding device according to claim 1, wherein the fluid supplying means includes a water source that supplies water and causes it to be sprayed from the holding surface of the porous plate, and the cleaning liquid is mixed in the water supplied from the water source.

3. 2. The grinding apparatus according to claim 1, wherein the fluid supply means comprises: a water source for supplying water; a cleaning liquid source for supplying the cleaning liquid; and a mixing section for mixing the water supplied from the water source with the cleaning liquid supplied from the cleaning liquid source.

4. The fluid supply means includes an air supply source, and either sprays air alone onto the holding surface of the porous plate, or mixes the air with another fluid that can be supplied from the fluid supply means and sprays the air from the holding surface of the porous plate. A grinding device according to any one of claims 1 to 3.

5. A maintenance method for a grinding device comprising: a chuck table for suction-holding a wafer; a grinding means having a grinding wheel rotatably mounted thereon, the grinding wheel having annularly arranged grinding stones for grinding the wafer held on the chuck table; and a grinding water supply means for supplying grinding water to a contact area between the wafer held on the chuck table and the grinding stones, the method comprising: The chuck table includes a porous plate having a holding surface that suction-holds a wafer, a frame that surrounds the holding surface of the porous plate, suction means that communicates with the frame and generates a suction force on the holding surface of the porous plate, and fluid supply means that communicates with the frame and sprays a fluid onto the holding surface of the porous plate, a holding step of placing a wafer on the holding surface of the chuck table and activating the suction means to hold the wafer; a grinding step of supplying grinding water to a contact area between the wafer held on the chuck table and a grinding wheel to grind the wafer; a cleaning step in which, after the grinding step is completed, the fluid supply means is operated to spray a cleaning liquid containing either a surfactant, a dispersant, or a surfactant and a dispersant onto the holding surface of the porous plate to clean it and remove grinding debris from the porous plate.

Images