Chuck table and dry polishing apparatus

Abstract

To surely prevent a wafer from being damaged by polishing chips even when dry- polishing is continuously performed for a long time.SOLUTION: A plurality of suction ports 12a are annularly arranged in an upper surface of a frame body 10A of a chuck table 10, and the suction ports 12a are allowed to communicate with a suction source 9. A dry-polishing device 1 includes: a polishing unit 40 that dry-polishes a wafer W by a rotating polishing pad 45 having a polishing surface that is in contact with an upper surface of the wafer W held on a holding surface 11a of the chuck table 10 and is protruding radially outward from the wafer W; a control unit 80; suction passages 15 to 17 that allow the suction ports 12a of the chuck table 10 to communicate with the suction source 9; and a valve V4 disposed in the suction passages 15 to 17 and configured to open / close the suction passages 15 to 17. The control unit 80 dry-polishes the upper surface of the wafer W held on the holding surface 11a, by the polishing pad 45 while the valve V4 is opened to allow the suction ports 12a to communicate with the suction source 9.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a chuck table for holding a wafer and a dry polishing apparatus for dry-polishing the wafer held on the chuck table.

Background Art

[0002] In the manufacturing process of semiconductor devices such as ICs and LSIs, in order to miniaturize and reduce the weight of the semiconductor devices, the back surface of the wafer is ground and the wafer is thinned to a predetermined thickness. The grinding of this wafer is performed by pressing a grinding wheel against the back surface (upper surface in the processing state) of the wafer while rotating the grinding wheel at high speed. When the back surface of the wafer is ground by such a grinding method, grinding marks remain on the back surface (grinding surface) of the wafer, and these grinding marks cause a decrease in the flexural strength of the wafer.

[0003] Therefore, the back surface (grinding surface) of the wafer is polished by a polishing apparatus to remove the grinding marks. Here, as a polishing apparatus, a dry polishing apparatus that polishes a wafer (dry polish) without using a polishing liquid (slurry) is known (see, for example, Patent Document 1). In such a dry polishing apparatus, the wafer is polished by pressing a dry polishing pad containing abrasive grains against the wafer.

[0004] In the dry polishing of a wafer by such a dry polishing apparatus, there are a portion that contacts the wafer and a portion that protrudes radially outward from the wafer on the polishing surface of the polishing pad. By injecting air onto the portion of the polishing surface that protrudes from the wafer, the abrasive debris adhering to the protruding portion of the polishing surface is removed. For this reason, abrasive debris scatters in the processing chamber for dry-polishing the wafer, and this scattered abrasive debris adheres to the chuck table and forms lumps. Then, the lumps of abrasive debris may detach from the chuck table due to the centrifugal force caused by the rotation of the chuck table and enter between the upper surface of the wafer and the polishing surface of the polishing pad, damaging the upper surface of the wafer.

[0005] Therefore, Patent Document 1 proposes a dry polishing apparatus that uses a dust collector to draw air from the processing chamber, generating an airflow within the chamber, and using this airflow to prevent polishing debris from adhering to the chuck table. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-048339 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, as proposed in Patent Document 1, even if the processing chamber is filled with dust by a dust collector to generate airflow within the chamber, if polishing is performed continuously for a long period of time, polishing debris may adhere to the chuck table and the walls inside the processing chamber, and this attached polishing debris may detach and damage the upper surface of the wafer.

[0008] The present invention has been made in view of the above problems, and its object is to provide a chuck table and a dry polishing apparatus that can reliably prevent damage to wafers by polishing debris even when dry polishing is performed continuously for a long period of time. [Means for solving the problem]

[0009] To solve the above problems, The present invention A porous member having a holding surface for holding a wafer, Multiple suction ports are arranged in a ring shape on the upper surface, surrounding the outer circumference of the holding surface. A frame that houses the porous member with the holding surface exposed. A dry polishing apparatus comprising: a holding means for holding and rotating a wafer on the holding surface of a chuck table having a chuck table; a polishing unit for dry polishing a wafer with a polishing pad that rotates, having a polishing surface that contacts the upper surface of the wafer so as to cover the entire upper surface of the wafer held on the holding surface and extending radially outward from the wafer; and a control unit, wherein the control unit comprises a suction passage for connecting the suction port of the chuck table to a suction source, and a valve disposed in the suction passage for opening and closing the suction passage, and the control unit sucks up polishing debris at the suction port when polishing the upper surface of the wafer held on the holding surface with the polishing pad while the valve is open and the suction port is in communication with the suction source. Dry polishing equipment. [Effects of the Invention]

[0011] According to the present invention, when dry polishing of a wafer is performed using a polishing pad, the control unit opens a valve and connects a plurality of suction ports opening on the upper surface of the chuck table to a suction source, so that polishing debris generated by dry polishing is sucked in along with air from the plurality of suction ports. This suppresses the scattering of polishing debris generated by dry polishing of the wafer within the processing chamber and prevents the polishing debris from adhering to the chuck table. Therefore, even if dry polishing of the wafer is performed continuously for a long time, the polishing debris will not adhere to the chuck table and form clumps, preventing the problem of clumps of polishing debris getting between the polishing pad and the wafer and damaging the polished surface of the wafer. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view showing a part of the dry polishing apparatus according to the present invention, with a breakaway section. [Figure 2] This is a perspective view of the frame of the chuck table according to the present invention, seen from the top side. [Figure 3] This is a perspective view of the frame of the chuck table according to the present invention, seen from the bottom. [Figure 4] This is a side view of a broken section showing the state of the dry polishing apparatus according to the present invention during the polishing process. [Figure 5] This is a plan view showing the positional relationship between the wafer, the chuck table, and the polishing pad during polishing in the dry polishing apparatus according to the present invention. [Figure 6] This is a cross-sectional side view showing the state of the dry polishing apparatus according to the present invention during cleaning. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0014] [Configuration of a dry polishing machine] First, the configuration of the dry polishing apparatus 1 according to the present invention will be described. In the following description, the directions indicated by the arrows in FIG. 1 are defined as the X-axis direction (left-right direction), the Y-axis direction (front-back direction), and the Z-axis direction (up-down direction), respectively.

[0015] The dry polishing apparatus 1 shown in FIG. 1 is an apparatus for dry-polishing a thin disk-shaped wafer W (see FIGS. 4 and 5) which is an object to be polished, and includes a chuck table 10 for holding the wafer W, a holding means 20 including the chuck table 10 and a rotation mechanism 21 for rotationally driving the chuck table 10, a moving mechanism 30 for moving the chuck table 10 in the Y-axis direction (front-back direction), a polishing unit 40 for dry-polishing the wafer W held by the chuck table 10, a lifting mechanism 50 for moving the polishing unit 40 up and down in the Z-axis direction (up-down direction), an air nozzle 60 for injecting air toward the polishing pad 45 of the polishing unit 40, a cleaning water nozzle 70 for injecting cleaning water toward the upper surface of the chuck table 10 from which the wafer W has been removed after dry polishing, and a control unit 80 as a main component.

[0016] Here, the wafer W is made of a single crystal silicon base material, and a plurality of devices (not shown) are formed on the surface facing downward in the state shown in FIG. 4. These devices are protected by a protection tape (not shown) attached to the surface of the wafer W. Then, the wafer W is held by the chuck table 10 with its surface (the lower surface in FIG. 4), and its back surface (the upper surface in FIG. 1) is dry-polished by the polishing unit 40.

[0017] Next, the configurations of the main components constituting the dry grinding apparatus 1, namely, the chuck table 10, the holding means 2, the moving mechanism 30, the polishing unit 40, the lifting mechanism 50, the air nozzle 60, the cleaning water nozzle 70, and the control unit 80, will be sequentially described below.

[0018] (Chuck Table) As shown in FIG. 4, the chuck table 10 according to the present invention is configured by connecting and integrating a disk-shaped upper and lower frame body 10A and a base body 10B, and incorporating a disk-shaped porous member 11 into a circular concave portion 10a (see FIG. 2) formed in the central portion of the frame body 10A. Here, the porous member 11 is made of porous ceramic or the like, and the upper surface thereof exposed to the frame body 10A constitutes a holding surface 11a for sucking and holding a disk-shaped wafer W.

[0019] And, as shown in FIG. 2, an annular groove 10b is formed on the outer peripheral portion of the upper surface of the frame body 10A of the chuck table 10 so as to surround the outer periphery of the holding surface 11a. A plurality (12 in the illustrated example) of circular suction ports 12a are opened in the annular groove 11b at an equal angular pitch in the circumferential direction (30° pitch in the illustrated example). Here, as shown in FIG. 4, a plurality (12 in the illustrated example) of circular suction paths 12 are formed in the vertical direction at a plurality of locations on the outer peripheral portion of the chuck table 10 (the locations where the suction ports 12a are opened). The upper ends of each suction path 12 are respectively opened as suction ports 12a in the annular groove 10b formed in the frame body 12A. Therefore, as shown in FIG. 3, a plurality (12 in the illustrated example) of suction paths 12 are opened in a circular hole shape on the outer peripheral portion of the lower surface of the frame body 10A. The number of the suction ports 12a and the suction paths 12 is arbitrary as long as it is plural, but it is preferably 10 or more.

[0020] Also, as shown in FIGS. 2 and 3, a plurality (8 in the illustrated example) of circular bolt holes 13 are vertically penetrated in the flange portion 12A1 formed on the outer peripheral portion of the frame body 10A of the chuck table 10 at an equal angular pitch in the circumferential direction (45° pitch in the illustrated example). As shown in FIG. 4, the frame body 10A is fastened to the base body 10B by screwing bolts 14 inserted into a plurality of bolt holes 13 (see FIGS. 2 and 3) formed therein into screw holes (not shown) formed in the base body 10B, and the two are integrated to form the chuck table 10.

[0021] (Holding means) The holding means 20 shown in Figure 4 comprises the chuck table 10 and a rotation mechanism 21 that rotates the chuck table 10 around its vertical central axis at a predetermined speed.

[0022] As shown in Figure 4, the chuck table 10 is horizontally mounted on the upper end of a rotating shaft 23 that extends vertically upward from the rotary joint 22. This rotating shaft 23 is rotatably supported by a support flange 39 by a bearing (ball bearing) 29. A large-diameter driven pulley 24 is connected to this rotating shaft 23. An electric motor 25, which is the drive source, is fixed vertically to a slider 31 provided in the moving mechanism 30 by a stay 28. A drive pulley 26, which has a smaller diameter than the driven pulley 24, is connected to the upper end of an output shaft (motor shaft) 25a that extends vertically upward from the electric motor 25. An endless timing belt 27 is wound around this drive pulley 26 and the driven pulley 24. The rotating mechanism 21 is composed of the electric motor 25, the drive pulley 26, the driven pulley 24, and the timing belt 27.

[0023] As shown in Figure 4, a circular, vertical passage 2 is formed at the axial center of the chuck table 10, the rotating shaft 23, and the rotary joint 22. The upper end of this passage 2 opens into the center of the lower surface of the porous member 11 of the chuck table 10. The lower end of the passage 2 is connected to a passage 3 formed laterally (horizontally) in the rotary joint 22, and a pipe 4 is connected to the passage 3.

[0024] Three branch pipes 4a, 4b, and 4c branch off from pipe 4. Branch pipe 4a is connected to a suction source 5, such as a vacuum pump, via valve V1. Branch pipe 4b is connected to an air supply source 6, such as an air compressor, via valve V2, and branch pipe 4c is connected to a water supply source 7, such as a water pump, via valve V3. Each of the valves V1 to V3 is electrically connected to a control unit 80, and their opening and closing operations are controlled by the control unit 80. A pressure gauge 8 is installed in the middle of pipe 4.

[0025] Furthermore, suction passages 15 are formed vertically in the chuck table 10, the rotating shaft 23, and the rotary joint 22. The upper end of each suction passage 15 is connected to a plurality (12 in this embodiment) of suction passages 16 that extend radially along the radial direction of the chuck table 10 (base 10B). Each suction passage 16 is connected to a plurality (12 in this embodiment) of the aforementioned suction passages 12 that are formed vertically on the outer circumference of the chuck table 10.

[0026] On the other hand, the lower end of the suction passage 15 is connected to a suction passage 17 formed laterally (horizontally) in the rotary joint 22, and a pipe 18 is connected to the suction passage 17. The pipe 18 is connected to a suction source 9 via a valve V4. The valve V4 is electrically connected to the control unit 80. Therefore, when the opening and closing operation of the valve V4 is controlled by the control unit 80, the multiple suction ports 12a opening in the annular groove 10b of the chuck table 10 are selectively connected to the suction source 9 and a vacuum is created. The suction source 9 may be a vacuum pump capable of sucking up water and gas, an ejector that supplies air to generate negative pressure, or an exhaust pump that sucks up gas. When using an exhaust pump, it is advisable to place a gas-liquid separation unit between the chuck table and the exhaust pump to separate gas and liquid.

[0027] (moving mechanism) As shown in Figure 1, the dry polishing apparatus 1 according to this embodiment is equipped with a rectangular box-shaped base 100 that is long in the Y-axis direction (front-to-back direction), and a rectangular block-shaped internal base 101 is housed inside this base 100. A moving mechanism 30 is provided on this internal base 101 for moving the chuck table 10 and the wafer W held by its holding surface 11a along the Y-axis direction (front-to-back direction). Specifically, the moving mechanism 30 moves the chuck table 10 between the processing position P1 shown in Figure 1 (the position where the wafer W is dry polished by the polishing unit 40) and the transport position P2 (the position where the wafer W is loaded into and unloaded from the holding surface 11a of the chuck table 10).

[0028] The above-described moving mechanism 30 includes a block-shaped slider 31, which is slidable in the Y-axis direction along a pair of left and right guide rails 32 that are arranged parallel to each other along the Y-axis direction (front-rear direction). Therefore, the holding means 20 (see Figure 4), which includes a chuck table 10 and a rotation mechanism 21 supported by the slider 31, is slidable along the Y-axis direction together with the slider 31.

[0029] A rotatable ball screw shaft 33 extending in the Y-axis direction (front-to-back direction) is positioned between a pair of left and right guide rails 32 on the internal base 101. One end of the ball screw shaft 33 in the Y-axis direction (the left end in Figure 1) is connected to a reversible electric motor 34, which is the drive source. The other end of the ball screw shaft 33 in the Y-axis direction (the right end in Figure 1) is rotatably supported on the internal base 101 by a bearing 35 erected on the internal base 101. A pair of nut members (not shown), which protrude downward from the slider 31, are screwed onto the ball screw shaft 33.

[0030] Therefore, when the electric motor 34 rotates the ball screw shaft 33 in forward and reverse directions, a nut member (not shown) that screws onto the ball screw shaft 33 slides along the ball screw shaft 33 in the Y-axis direction (front-back direction) together with the slider 31. As a result, the chuck table 10 also moves integrally along the Y-axis direction together with the slider 31. Consequently, the wafer W, which is the workpiece to be polished, and the holding means 20 shown in Figure 4, which are held on the holding surface 11a of the chuck table 10 (see Figures 1 and 2), also move integrally along the Y-axis direction.

[0031] Furthermore, as shown in Figure 1, a rectangular opening 36, elongated in the Y-axis direction, is formed on the upper surface of the base 100, and the chuck table 10 faces this opening 36. The area around the chuck table 10 in the opening 36 on the upper surface of the base 100 is covered by a rectangular plate-shaped cover 37, and the front and rear portions of the cover 37 (in the -Y direction and +Y direction) of the opening 36 are covered by a pair of bellows-shaped expandable covers 38 that move and expand together with the cover 37. Therefore, no matter what position the chuck table 10 is in in the Y-axis direction, the opening 36 is always covered by the expandable covers 38, preventing foreign matter from entering the interior of the base 100 through the opening 36.

[0032] (Polishing unit) The polishing unit 40 comprises a spindle motor 42 fixed to a holder 41, a vertical spindle 43 rotationally driven by the spindle motor 42, a disc-shaped mount 44 attached to the lower end of the spindle 43, a mount 34 connected to the lower end of a 31 detachably mounted on the lower surface of the mount 44, and a disc-shaped polishing pad 45 detachably mounted on the lower surface of the mount 34. Here, the polishing pad 45 is constructed by bonding a disc-shaped pad material 45b, such as a nonwoven fabric or urethane containing abrasive grains, to the lower surface of a disc-shaped base 45a.

[0033] Here, as shown in Figure 5, the polishing pad 45 has an area that covers the wafer W held on the holding surface 11a of the chuck table 10 (see Figures 1 and 2) from above. Specifically, the outer diameter φD of the polishing pad 45 is set to be larger than the outer diameter φd of the wafer W (φD > φd), and the polishing pad 45 is rotationally driven around a center O2 that is eccentric by ε from the center O1 of the wafer W as shown in Figure 5. Therefore, a crescent-shaped overhang (shaded portion) 45A is formed on the polishing surface of the polishing pad 45, extending beyond the wafer W held on the holding surface 11a of the chuck table 10 in plan view.

[0034] Furthermore, as shown in Figure 1, a thickness measuring device 46 is provided on the upper part of the spindle motor 42 for optically measuring the thickness of the wafer W during dry polishing.

[0035] Incidentally, as shown in Figure 1, a rectangular box-shaped case 90 is installed at the processing position P1 on the base 100, and as shown in Figure 4, the wafer W being dry polished, the chuck table 10 that holds it, and the polishing pad 45 are housed in the processing chamber S inside this case 90.

[0036] (Lifting mechanism) As shown in Figure 1, a rectangular box-shaped column 102 is erected vertically on the +Y-axis end (rear end) of the upper surface of the base 100, and a lifting mechanism 50 is provided on the -Y-axis end face (front) of this column 102. This lifting mechanism 50 moves the polishing unit 40 up and down in a direction perpendicular to the holding surface 11a of the chuck table 10 (Z-axis direction), and moves a rectangular plate-shaped lifting plate 51 attached to the back of the holder 41 up and down in the Z-axis direction (vertical direction) along a pair of left and right guide rails 52, together with the holder 41 and the spindle motor 42, spindle 43, polishing pad 45, etc. held by the holder 41. Here, the pair of left and right guide rails 52 are arranged perpendicular and parallel to each other on the front surface of the column 102.

[0037] As shown in Figure 1, a rotatable ball screw shaft 53 is erected vertically along the Z-axis direction (up and down direction) between a pair of left and right guide rails 52, and the upper end of the ball screw shaft 53 is connected to a reversible electric motor 54, which is the drive source. The lower end of the ball screw shaft 53 is rotatably supported by a bearing (not shown) on a column 102, and a nut member (not shown) that protrudes horizontally toward the rear (+Y-axis direction) from the back of the lifting plate 51 is screwed onto this ball screw shaft 53.

[0038] (Air nozzle) The air nozzle 60 is used to spray air towards the crescent-shaped overhang 45A (see Figure 5) that extends radially outward from the outer circumference of the polishing surface of the polishing pad 45 during dry polishing of the wafer W by the polishing unit 40, and is erected vertically behind the chuck table 10 (+Y axis side). The air nozzle 60 is movable along the front-rear direction (Y axis direction) together with the chuck table 10.

[0039] As shown in Figure 5, the upper surface of the air nozzle 60 has three circular nozzles 60a that open along the radial direction (left-right direction in Figure 5) of the wafer W (polishing pad 45). As shown in Figure 4, the air nozzle 60 is connected to an air supply source 62 such as an air compressor by piping 61, and a valve V5 is provided in the middle of the piping 61. The valve V5 is electrically connected to a control unit 80, and its opening and closing operation is controlled by the control unit 80.

[0040] (Washing water nozzle) The cleaning water nozzle 70 sprays cleaning water, such as pure water, onto the wafer W and chuck table 10 after dry polishing by the polishing unit 40 has been completed and the wafer has been transported to the transport position P2 shown in Figure 1, thereby removing polishing debris adhering to them. The cleaning water nozzle 70 is made of a pipe material bent in an inverted L shape. As shown in Figure 1, the cleaning water nozzle 70 is erected to the side (-X axis side) of the opening 36 on the upper surface of the base 100, and its nozzle 70a opens to the right (+X axis direction).

[0041] As shown in Figure 6, the water injection nozzle 70 is connected to a water supply source 72, such as a water pump, by piping 71, and a valve V6 is connected in the middle of piping 71. Here, the valve V6 is electrically connected to a control unit 80, and its opening and closing operation is controlled by the control unit 80.

[0042] (Control Unit) The control unit 80 includes a CPU (Central Processing Unit) that performs calculations according to a control program, and memory such as ROM (Read Only Memory) and RAM (Random Access Memory). This control unit 80 performs functions such as opening and closing the multiple valves V1 to V6, as well as controlling the drives of the electric motor 25 of the rotating mechanism 21, the electric motor 34 of the moving mechanism 30, the spindle motor 42 of the polishing unit 40, and the electric motor 54 of the lifting mechanism 50.

[0043] [Operation of dry polishing equipment] Next, we will describe the dry polishing of wafer W using the dry polishing apparatus 1 configured as described above.

[0044] When dry polishing a wafer W, the wafer W is placed face down on the holding surface 11a of the chuck table 10 located at the transport position P2 shown in Figure 1. Then, the control unit 80 opens valve V1 shown in Figure 4, and vacuums the porous member 11 of the chuck table 10. That is, when valve V1 is opened, the air inside the porous member 11 is sucked out by the suction source 5 through the communication passages 2, 3, piping 4 and branch pipe 4a, so that negative pressure is generated in the porous member 11, and the wafer W placed on the upper surface (holding surface 11a) of the porous member 11 is sucked and held on the holding surface 11a by the negative pressure. At this time, the other valves V2 to V6 are closed.

[0045] From the above state, the moving mechanism 30 shown in Figure 1 is driven to move the chuck table 10 from the transport position P2 in the +Y axis direction (rearward), and the chuck table 10 and the wafer W held by it are moved to the processing position P1 and positioned below the polishing pad 45 of the polishing unit 40. That is, when the electric motor 34 is started and the ball screw shaft 33 rotates, a slider 31 to which a nut member (not shown) that screws onto the ball screw shaft 33 is attached slides along the pair of left and right guide rails 32 in the +Y axis direction together with the chuck table 10, so that the wafer W held on the holding surface 11a of the chuck table 10 is positioned below the polishing pad 45 of the polishing unit 40 at the processing position P1.

[0046] Furthermore, the electric motor 25 of the rotating mechanism 21 shown in Figure 4 is driven to rotate the chuck table 10 at a predetermined rotational speed (for example, 300 rpm) in the direction of the arrow shown (counterclockwise). That is, when the electric motor 25 is driven, the rotation of the output shaft 25a of the electric motor 25 is transmitted from the rotating shaft 23 to the chuck table 10 while being reduced in speed via the drive pulley 26, timing belt 27 and driven pulley 24, and the chuck table 10 and the wafer W held therein are driven to rotate at a predetermined speed. At the same time, the spindle motor 42 of the polishing unit 40 is started to rotate the polishing pad 45 at a predetermined speed (for example, 1000 rpm) in the direction of the arrow shown (counterclockwise, the same direction as the rotation of the wafer W).

[0047] As described above, with the wafer W and polishing pad 45 rotating, the lifting mechanism 50 is driven to lower the polishing pad 45 in the -Z axis direction. That is, when the electric motor 54 is driven and the ball screw shaft 53 rotates, the lifting plate 51, which is provided with a nut member (not shown) that screws onto the ball screw shaft 53, lowers in the -Z axis direction together with the polishing pad 45. Then, as shown in Figures 4 and 5, the lower surface (polishing surface) of the polishing pad 45 comes into contact with the entire upper surface (back surface) of the wafer W. As a result, the upper surface of the wafer W is dry polished by the polishing pad 45, and grinding marks remaining on the upper surface of the wafer W are removed, thereby increasing the flexural strength of the wafer W.

[0048] In this embodiment, when dry polishing of the upper surface of the wafer W is performed by the polishing pad 45 as described above, the control unit 80 opens both valves V4 and V5. Then, compressed air from the air supply source 62 is sprayed through the piping 61 from the nozzle 60a of the air nozzle 60 toward the lower surface (polishing surface) of the crescent-shaped overhang portion 45A (see Figure 5) of the polishing pad 45 that extends radially outward from the outer circumference of the wafer W. As a result, polishing debris generated by the dry polishing of the wafer W and adhering to the overhang portion 45A on the lower surface (polishing surface) of the polishing pad 45 is blown away by the compressed air and removed from the lower surface (polishing surface) of the polishing pad 45.

[0049] As described above, the polishing debris removed from the lower surface (polishing surface) of the polishing pad 45 is sucked up along with air from a plurality of (12 in this embodiment) suction ports 12a opening on the upper surface of the chuck table 10. This sucked-up polishing debris and air are then sequentially drawn into the suction source 9 via suction passages 12, 16, 15, 17 and piping 18. This suppresses the scattering of polishing debris generated by dry polishing of the wafer W within the processing chamber S and prevents the polishing debris from adhering to the chuck table 10. Therefore, even if dry polishing of the wafer W is performed continuously for a long time, the polishing debris will not adhere to the chuck table 10 and form clumps, preventing the clumps of polishing debris from getting between the polishing pad 45 and the wafer W and damaging the polished surface of the wafer W.

[0050] As described above, once the dry polishing of the wafer W at the processing position P1 shown in Figure 1 is complete, the control unit 80 drives the moving mechanism 30 to move the chuck table 10 and the wafer W held therein to the transport position P2. Then, once the dry polished wafer W is removed from the chuck table 10, the control unit 80 opens the valve V6 shown in Figure 6. As a result, cleaning water from the water supply source 72 is supplied to the cleaning water nozzle 70 via the piping 71, and the cleaning water is sprayed from the nozzle 70a toward the upper surface of the chuck table 10, cleaning the upper surface of the chuck table 10 with the cleaning water. Furthermore, by opening valve V4 at this time and drawing the cleaning water used to clean the chuck table 10 through the multiple suction ports 12a opening on the upper surface of the chuck table 10 and directing it through the suction passages 12, 16, 15, 17 and piping 18 to the suction source 9, the suction ports 12a and the connecting passages 12, 16, 15, 17 can be cleaned with the cleaning water.

[0051] Alternatively, while cleaning the chuck table 10 with cleaning water sprayed from the cleaning water nozzle 70, water from the water supply source 7, or a two-fluid mixture of water from the water supply source 7 and air from the air supply source 6, may be sprayed onto the holding surface 11a of the chuck table 10, and this water or two-fluid mixture may be sucked up from multiple suction ports 12a to clean the suction ports 12a and suction passages 12, 16, 15, and 14.

[0052] In other words, the control unit 80 closes valves V1 and V2 and opens valves V3 and V4. Then, water from the water supply source 7 is sprayed onto the holding surface 11a of the chuck table 10 via the branch pipe 4c, piping 4 and connecting passages 3 and 2. This water sprayed onto the holding surface 11a is then drawn into the suction source 9 via multiple suction ports 12a opening on the upper surface of the chuck table 10, through suction passages 12, 16, 15, 17 and piping 18. Alternatively, the control unit 80 closes valve V1 and opens valves V2, V3, and V4. As a result, the two fluids, a mixture of air from the air supply source 6 and water from the water supply source 7, are sprayed onto the holding surface 11a of the chuck table 10 via the branch pipes 4b, 4c, piping 4, and connecting passages 3, 2. The two fluids sprayed onto the holding surface 11a are then sucked up by the suction source 9 through multiple suction ports 12a opening on the upper surface of the chuck table 10, via suction passages 12, 16, 15, 17 and piping 18. Consequently, as described above, water or the two fluids can be sucked up from the multiple suction ports 12a to clean the suction ports 12a and the suction passages 12, 16, 15, 14.

[0053] In addition, the chuck table according to the present invention has been described above as being provided in a dry polishing apparatus for dry polishing wafers, but the chuck table according to the present invention may also be provided in any other processing apparatus such as a wafer grinding apparatus or a cutting apparatus.

[0054] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the technical idea described in the claims, specification, and drawings. [Explanation of Symbols]

[0055] 1: Dry grinding machine, 2,3: Connecting passage, 4: Piping, 4a~4c: Branch pipe, 5: Suction source, 6: Air supply source, 7: Water supply source, 8: Pressure gauge, 9: Suction source, 10: Chuck table, 10A: Frame, 10A1: Flange section, 10B: Base, 10a: Recess, 10b: Annular groove, 11: Porous member, 11a: Holding surface, 12: Suction passage, 12a: Suction port, 13: Bolt hole, 14: Bolt, 15-17: Suction passage, 18: Piping, 20: Holding means, 21: Rotating mechanism, 22: Rotary joint, 23: Rotating shaft, 24: Driven pulley, 25: Electric motor, 25a: Output shaft of electric motor (motor shaft), 26: Drive pulley, 27: Timing belt, 28: Stay, 29: Bearing, 30: Moving mechanism 31: Slider, 32: Guide rail, 33: Ball screw shaft, 34: Electric motor, 35: Bearing, 36: Opening, 37: Cover, 38: Expandable cover, 39: Support flange, 40: Polishing unit, 41: Holder, 42: Spindle motor, 43: Spindle, 44: Mount, 45: Polishing pad, 45A: Protruding part of polishing pad, 45a: Base, 45b: Pad material, 46: Thickness measuring instrument, 50: Lifting mechanism, 51: Lifting plate, 52: Guide rail, 53: Ball screw shaft, 54: Electric motor, 60: Air nozzle, 60a: Spray nozzle, 61: Piping, 62: Air supply source, 70: Washing water nozzle, 70a: Spray nozzle, 71: Piping, 72: Water supply source, 80: Control unit, 90: Case, 100: Base, 101: Inner base, 102: Column, φD: Outer diameter of polishing pad φd: outer diameter of the wafer, P1: processing position, P2: transport position, S: processing chamber, V1~V6: Valve, W: Wafer

Claims

1. A dry polishing apparatus comprising: a holding means for holding and rotating a wafer on the holding surface of a chuck table having a porous member having a holding surface for holding a wafer; a frame having a plurality of suction ports arranged in an annular manner on its upper surface so as to surround the outer circumference of the holding surface and housing the porous member with the holding surface exposed; a polishing unit for dry polishing a wafer with a polishing pad that rotates, contacting the upper surface of the wafer so as to cover the entire upper surface of the wafer held on the holding surface, and having a polishing surface that extends radially outward from the wafer; and a control unit, the apparatus comprising: The chuck table comprises a suction passage that connects the suction port to a suction source, and a valve disposed in the suction passage that opens and closes the suction passage. The control unit is A dry polishing apparatus that, with the valve open and the suction port connected to the suction source, sucks up polishing debris at the suction port while polishing the upper surface of a wafer held on the holding surface with the polishing pad.

2. The dry polishing apparatus according to claim 1, wherein an annular groove is formed on the upper surface of the frame so as to surround the outer circumference of the holding surface, and the suction port is arranged in the annular groove.

3. The dry polishing apparatus according to claim 1 or 2, further comprising an air nozzle for spraying air toward the polishing surface of the polishing pad that extends radially outward from the wafer.

4. A moving mechanism moves the chuck table to a polishing position where the wafer is dry polished by the polishing unit and to a transport position where the wafer is loaded into and unloaded from the holding surface. The system includes a washing water nozzle that supplies washing water to the chuck table which has been moved to the transport position by the moving mechanism, The control unit is The dry polishing apparatus according to claim 1, comprising controlling the rotation of the chuck table moved to the transport position, supplying cleaning water from the cleaning water nozzle to the suction port, and opening the valve to connect the suction port to the suction source, thereby sucking the cleaning water from the suction port to clean the suction port and the suction path.

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