Suction table
The suction table's chamfered grooves address the issue of debris accumulation and drying, ensuring smooth debris flow and preventing workpiece damage in grinding apparatuses.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- DISCO CORP
- Filing Date
- 2022-07-27
- Publication Date
- 2026-06-02
Smart Images
Figure 0007869068000001 
Figure 0007869068000002 
Figure 0007869068000003
Abstract
Description
Technical Field
[0001] The present invention relates to a suction table that sucks and holds a workpiece on a suction surface.
Background Art
[0002] For example, a grinding apparatus for grinding a workpiece such as a wafer includes a chuck table for holding the workpiece, a grinding means for grinding the workpiece held by the chuck table, and a transfer means for loading or unloading the workpiece with respect to the chuck table. Here, the transfer means includes a transfer pad having a suction groove formed in a suction surface and a moving mechanism for moving the transfer pad, and the suction groove of the transfer pad is communicated with a suction source so that the workpiece is sucked and held by the transfer pad (see, for example, Patent Documents 1 and 2).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0004] By the way, in a workpiece grinding apparatus, when separating the workpiece from the chuck table, the grinding fluid containing grinding chips generated during grinding of the workpiece is ejected onto the holding surface of the chuck table. Then, when the transfer pad sucks and holds the upper surface of the workpiece, the transfer pad sucks the grinding fluid containing grinding chips ejected from the chuck table.
[0005] As described above, when the transfer pad sucks the grinding fluid, the grinding chips contained in the grinding fluid adhere to the corner portions of the suction grooves and dry, and the dried grinding chips may adhere to the workpiece and damage the workpiece.
[0006] The present invention has been made in view of the above problems, and its object is to provide a suction table in which processing debris does not accumulate in the suction groove. [Means for solving the problem]
[0007] To achieve the above objective, the present invention provides a suction table that holds a workpiece by suction on a suction surface, wherein the suction surface A suction groove that opens in a ring shape, and an opening on the bottom surface of the suction groove A suction port, and the suction port A communication passage that connects to the suction source, Equipped with, Suction groove Bottom and Suction groove A chamfer is formed on the concave corner portion that connects to the side, The connecting passage The side and The bottom surface of the suction groove A characteristic feature is that a chamfer is formed on the convex corner portion connecting the two parts. [Effects of the Invention]
[0008] According to the present invention, since the concave and convex corners of the suction grooves of the suction table are chamfered, the processing debris contained in the processing fluid sucked up by the suction grooves flows smoothly and without resistance through the concave and convex corners of the suction grooves, and does not accumulate and dry out in those corners. Therefore, damage to the workpiece held by the suction table due to processing debris is reliably prevented. [Brief explanation of the drawing]
[0009] [Figure 1] This is a perspective view showing a part of a grinding apparatus equipped with a suction table (conveyor pad) according to the present invention, in a cutaway view. [Figure 2] This is a partial perspective view of a transport means equipped with a suction table (transport pad) according to the present invention. [Figure 3] This is a cross-sectional side view of the main part of a transport means equipped with a suction table (transport pad) according to the present invention. [Figure 4] (a) is an enlarged detail view of section A in Figure 3, and (b) is a diagram similar to (a) of a conventional suction table. [Figure 5] This is a bottom view of the suction table (transport pad) according to the present invention. [Figure 6]This is a bottom view of a suction table (transport pad) according to another embodiment of the present invention. [Figure 7] Figure 6 is a cross-sectional view along line BB. [Figure 8] This is an enlarged detailed view of section C in Figure 7. [Modes for carrying out the invention]
[0010] Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0011] [Configuration of the grinding machine] First, the basic configuration of a grinding apparatus equipped with a transport pad as one form of the suction table according to the present invention will be described below with reference to Figure 1. In the following description, the arrow directions shown in Figure 1 will be described as the X-axis direction (left and right direction), the Y-axis direction (front and back direction), and the Z-axis direction (up and down direction), respectively.
[0012] The grinding apparatus 1 shown in Figure 1 grinds the back surface (top surface in Figure 1) of a disc-shaped wafer W, which is the workpiece, and comprises the following components.
[0013] In other words, the grinding apparatus 1 mainly comprises a chuck table 10 for holding a wafer W, a grinding unit 20 for grinding the back surface (top surface in Figure 1) of the wafer W held on the holding surface 10a of the chuck table 10, a spinner cleaning means 30 for cleaning the wafer W, a robot 40 for loading and unloading wafer W into and out of a cassette 2, a first transport means 50 for holding the wafer W aligned on the alignment table 4 and transferring it to the chuck table 10, and a second transport means 60 for holding the wafer W after grinding and transporting it from the chuck table 10 to the spinner cleaning means 30.
[0014] Here, the wafer W is composed of a single-crystal silicon base material. On the surface facing downward in the state shown in FIG. 1, a plurality of devices (not shown) are formed, and these devices are protected by a protective tape (not shown) adhered to the surface of the wafer W. Then, the wafer W is sucked and held on the holding surface 10a of the chuck table 10 with its surface (the lower surface in FIG. 1), and the back surface (the upper surface in FIG. 1) is ground by a grinding unit 20 as described later.
[0015] Next, the configurations of the chuck table 10, the grinding unit 20, the spinner cleaning means 30, the robot 40, the first transfer means 50, and the second transfer means 60, which are the main components of the grinding apparatus 1, will be described respectively.
[0016] (Chuck Table) The chuck table 10 is a disk-shaped member, and a disk-shaped porous member 10A made of porous ceramic or the like is incorporated in the central portion thereof. Here, the upper surface of the porous member 10A constitutes a holding surface 10a for sucking and holding the disk-shaped wafer W, and the holding surface 10a is selectively connected to a suction source (not shown).
[0017] Then, the chuck table 10 is rotationally driven at a predetermined speed around its axis by a rotation mechanism (not shown) including an electric motor which is a drive source provided below it, and can reciprocate in the Y-axis direction (front-rear direction) between the processing position P1 and the delivery position P2 by a horizontal movement mechanism (not shown) provided below it. The horizontal movement mechanism (not shown) is constituted by a known ball screw mechanism or the like.
[0018] Furthermore, a thickness measuring device 5 is positioned near the chuck table 10 located at the processing position P1 on the base 1A. This thickness measuring device 5 is a height gauge and includes a first contact 5a that contacts the upper surface of the wafer W held by the chuck table 10, and a second contact 5b that contacts the upper surface of the outer periphery of the chuck table 10. Therefore, the thickness of the wafer W during grinding can be measured by subtracting the height of the chuck table 10 measured by the second contact 5b from the height of the wafer W measured by the first contact 5a.
[0019] (Grinding unit) As shown in Figure 1, the grinding unit 20 comprises a holder 21 with an opening at the top, a spindle motor 22 which is a rotational drive source fixed vertically to the holder 21, a spindle 23 which is rotationally driven by the spindle motor 22, a disc-shaped mount 24 attached to the lower end of the spindle 23, and a grinding wheel 25 which is detachably mounted on the lower surface of the mount 24. Here, a plurality of rectangular block-shaped grinding wheels 25a, which are workpieces, are mounted in an annular shape on the grinding wheel 25.
[0020] Incidentally, the grinding unit 20 can be raised and lowered along a direction perpendicular to the holding surface 10a of the chuck table 10 (Z-axis direction) by a vertical movement mechanism 11. As shown in Figure 1, this vertical movement mechanism 11 is positioned on the -Y-axis end face (front face) of a rectangular box-shaped column 12 that is erected vertically on the +Y-axis end (rear end) of the upper surface of the base 1A. This vertical movement mechanism 11 raises and lowers a rectangular plate-shaped lifting plate 13 attached to the back of the holder 21 along a pair of left and right guide rails 14 along the Z-axis direction, together with the holder 21 and the spindle motor 22 and grinding wheel 25 held by the holder 21. Here, the pair of left and right guide rails 14 are arranged perpendicularly and parallel to each other on the front surface of the column 12.
[0021] Furthermore, a rotatable ball screw shaft 15 is erected vertically along the Z-axis direction (up and down direction) between a pair of left and right guide rails 14, and the upper end of the ball screw shaft 15 is connected to a reversible electric motor 16, which is the drive source. Here, the electric motor 16 is mounted vertically via a rectangular plate-shaped bracket 17 attached to the upper surface of the column 12. The lower end of the ball screw shaft 15 is rotatably supported by the column 12, and a nut member (not shown) that protrudes horizontally toward the rear (+Y-axis direction) from the back of the lifting plate 13 is screwed onto this ball screw shaft 15.
[0022] Therefore, by driving the electric motor 16 to rotate the ball screw shaft 15 in both forward and reverse directions, the lifting plate 13, to which a nut member (not shown) that screws onto the ball screw shaft 15 is attached, moves up and down in the Z-axis direction along the guide rail 14 together with the grinding unit 20.
[0023] (Spinner cleaning means) The spinner cleaning means 30 cleans the back surface of a wafer W after grinding of the back surface (top surface in Figure 1) has been completed, and comprises a spinner table 31 that holds and rotates the wafer W after grinding, a cleaning water nozzle 32 that sprays cleaning water toward the back surface of the wafer W, and a movable polygonal cylindrical cover 33 that covers the spinner table 31 and the cleaning water nozzle 32. Pure water is preferably used as the cleaning water.
[0024] (robot) The robot 40 is a multi-joint robot, and a plate-shaped robot hand 43 is attached to the tip of a rectangular box-shaped mounting section 41 via a holder 42. The robot 40 is also provided with a horizontal movement mechanism 44 for moving the mounting section 41 and the robot hand 43 horizontally, and a lifting mechanism 45 for raising and lowering the mounting section 41 and the robot hand 43.
[0025] (First and second transport means) The basic configuration of the first transport means 50 and the second transport means 60 is the same. The first transport means 50 is configured by horizontally supporting a disc-shaped transport pad 53 at the tip of an arm 52 that is horizontally mounted on the upper end of a vertical rotation axis 51. Similarly, the second transport means 60 is configured by horizontally supporting a disc-shaped transport pad 63 at the tip of an arm 62 that is horizontally mounted on the upper end of a vertical rotation axis 61. When the respective rotation axes 51, 61 of the first transport means 50 and the second transport means 60 are rotated by a predetermined angle by a rotation mechanism (not shown), the transport pads 53, 63 attached to the tips of the respective arms 52, 62 move (rotate) horizontally around the respective rotation axes 51, 61.
[0026] Here, the details of the configuration of the suction pad 63 of the second transport means 60 will be explained based on Figures 2 to 5.
[0027] As shown in Figures 2 and 3, the transport pad 63 is horizontally supported by three pins 65 on an annular retaining ring 64 attached to the tip of the arm 62. As shown in Figure 3, the lower end of a pipe 67, which extends vertically downward through the center of the retaining ring 64, is connected to a vertical circular passage 66 formed in the center of the upper surface of the suction pad 63. The second transport means 60, including the transport pad 63, can be raised and lowered along the vertical direction (Z-axis direction) by a lifting mechanism 68 shown in Figure 3.
[0028] As shown in Figure 3, the piping 67 branches into two branch pipes 67a and 67b. One branch pipe 67a is connected to an air supply source 69, such as an air compressor, via an electromagnetic valve V1, and the other branch pipe 67b is connected to a suction source 70, such as a vacuum pump, via an electromagnetic valve V2. Each of the electromagnetic valves V1 and V2 is electrically connected to a control unit (not shown), and their opening and closing operations are controlled by the control unit.
[0029] Furthermore, as shown in Figures 3 and 5, three concentric suction grooves 71, 72, and 73 are formed on the suction surface (bottom surface) 63a of the transport pad 63, and a connecting passage 74 is formed inside the suction pad 63, extending horizontally radially outward (to the right in Figures 3 and 5) from the connecting passage 66. This connecting passage 74 communicates with each of the suction grooves 71, 72, and 73 via circular suction ports 75, 76, and 77 that open into each of the suction grooves 71, 72, and 73, respectively.
[0030] Incidentally, Figure 4(a) shows the longitudinal cross-sectional shape of one suction groove 73. A concave corner (concave R chamfer) R1 is formed at the concave corner connecting the bottom surface (top surface) 73a and both inner and outer sides 73b and 73c of the suction groove 73, and a convex corner (convex R chamfer) R2 is formed at the convex corner connecting both inner and outer sides 73b and 73c and the suction surface (bottom surface) 63a. By the way, in the suction groove 173 formed on the conventional transport pad 163 shown in Figure 4(b), the concave corner connecting the bottom surface (top surface) 173a and both inner and outer sides 173b and 173c, and the convex corner connecting both inner and outer sides 173b and 173c and the suction surface (bottom surface) 163a are not chamfered, and both these concave and convex corners form right-angle corners.
[0031] Although Figure 4(a) shows only the longitudinal cross-sectional shape of one suction groove 73, the other two suction grooves 71 and 72 also have similar concave R-shaped chamfers (concave R chamfer) R1 and convex R-shaped chamfers (convex R chamfer) R2 formed on each concave and convex corner, respectively.
[0032] [Operation of grinding equipment] Next, the operation of the grinding apparatus 1 configured as described above will be explained with reference to Figure 1.
[0033] When grinding the wafer W, the robot 40 removes the wafer W from the cassette 2 before grinding. The wafer W removed from the cassette 2 is then aligned on the alignment table 4, and then carried by the first transport means 50 to the chuck table 10 waiting at the transfer position P2, where it is held by suction.
[0034] In the chuck table 10, the wafer W is placed face down on the holding surface 10a of the chuck table 10. Then, the porous member 10A is evacuated by a suction source (not shown), generating negative pressure in the porous member 10A, and the wafer W placed on the holding surface 10a of the porous member 10A is attracted and held on the holding surface 10a by the negative pressure.
[0035] From the above state, a horizontal movement mechanism (not shown) is driven to move the chuck table 10 to the processing position P1 in the direction of the +Y axis, and the wafer W held by suction on the chuck table 10 is positioned below the grinding wheel 25 of the grinding unit 20. Then, a rotation mechanism (not shown) is driven to rotate the chuck table 10 at a predetermined speed. At the same time, the spindle motor 22 is started to rotate the grinding wheel 25 at a predetermined speed.
[0036] As described above, with the wafer W and grinding wheel 25 rotating, the vertical movement mechanism 11 is activated to lower the grinding wheel 25 in the -Z axis direction. That is, when the electric motor 16 is driven and the ball screw shaft 15 rotates, the lifting plate 13, which is equipped with a nut member (not shown) that screws onto the ball screw shaft 15, descends in the -Z axis direction together with the holder 21 and the grinding wheel 25. Then, the lower surface (machining surface) of the grinding wheel 25a of the grinding wheel 25 comes into contact with the upper surface (back surface) of the wafer W. In this state, when the grinding wheel 25 is lowered further in the -Z axis direction by a predetermined amount (grinding allowance) from the lower surface of the grinding wheel 25a in contact with the upper surface of the wafer W, the upper surface of the wafer W is ground by the grinding wheel 25a by a predetermined amount. During grinding, grinding fluid is supplied to the contact area (machining area) between the grinding wheel 25a and the wafer W from a grinding fluid supply source (not shown). Furthermore, the thickness of the wafer W during grinding is measured by the thickness measuring instrument 5.
[0037] When the grinding process on the wafer W described above is completed, the vacuum of the porous member 10A of the chuck table 10 is stopped, and air is supplied to the porous member 10A from an air supply source (not shown) to separate the wafer W from the chuck table 10. As a result, the wafer W separates from the chuck table 10, and the grinding fluid containing grinding debris is ejected from the holding surface 10a of the porous member 10A.
[0038] From the above state, the transport pad 63 of the second transport means 60 sucks and holds the wafer W on the chuck table 10. That is, the electromagnetic valve V2 shown in Figure 3 is opened, and the negative pressure from the suction source 70 extends from the piping 67 through the connecting passages 66, 74 and suction ports 75, 76, 77 to the suction grooves 71, 72, 73. As a result, the wafer W is attracted by this negative pressure and sucked and held by the suction surface (bottom surface) 63a of the transport pad 63. At this time, the grinding fluid containing grinding debris sprayed onto the holding surface 10a of the chuck table 10 is sucked into each suction groove 71, 72, 73 by negative pressure. However, as shown in Figure 4(a) (Figure 4(a) shows only one suction groove 73), a concave R-shaped chamfer (concave R chamfer) R1 and a convex R-shaped chamfer (convex R chamfer) R2 are formed on the convex and concave corner portions of each suction groove 71, 72, 73. Therefore, the grinding debris contained in the grinding fluid sucked into each suction groove 71, 72, 73 passes smoothly through the concave R chamfer R1 and convex R chamfer R2 of each suction groove 71, 72, 73 without resistance and does not accumulate and dry in the concave and convex corner portions. Consequently, the problem of grinding debris accumulating and drying in the concave and convex corner portions of each suction groove 71, 72, 73 adhering to the workpiece W and damaging the workpiece W does not occur.
[0039] Then, when the wafer W is held by the transport pad 63, the transport pad 63 is raised by the lifting mechanism 68 shown in Figure 3, and the wafer W is separated from the chuck table 10. The rotation axis 61 is rotated by a predetermined angle by a rotation mechanism (not shown), causing the arm 62 and the transport pad 63 supported at its tip to rotate horizontally around the rotation axis 61 (see Figures 1 and 2), and the wafer W is transported to the spinner cleaning means 30, where it is placed on the spinner table 31 of the spinner cleaning means 30. When separating the wafer W, which is held by the transport pad 63, from the suction surface 63a of the transport pad 63, one of the electromagnetic valves V2 shown in Figure 3 is closed and the other electromagnetic valve V1 is opened. Air is supplied from the air supply source 69 through the piping 67 to the connecting passages 66, 74 and suction ports 75, 76, 77 of the transport pad 63 and then to the respective suction grooves 71, 72, 73. Air is then ejected from the respective suction grooves 71, 72, 73, allowing the wafer W to easily separate from the suction surface 63a of the transport pad 63 and be transferred to the spinner table 31.
[0040] In the spinner cleaning means 30, the spinner table 31 and the wafer W held by suction on it rotate at a predetermined speed, and cleaning water is sprayed from the cleaning water nozzle 32 toward the rotating wafer W, so that the upper surface (grinding surface) of the wafer W is cleaned by the cleaning water and foreign matter such as grinding debris adhering to the upper surface of the wafer W is removed. After cleaning is completed, the wafer W is held by suction by the robot hand 43 of the robot 40 and transported to the cassette 3 shown in Figure 1, where it is stored, and the series of grinding processes on the wafer W is completed.
[0041] [Another form of suction pad] Next, another embodiment of the transport pad according to the present invention will be described below with reference to Figures 6 to 8.
[0042] In another embodiment of the present invention, the transport pad 63' also has three concentric suction grooves 71, 72, and 73 formed on its suction surface (upper surface in Figure 6) 63a'. These suction grooves 71, 72, and 73 are connected to each other by a communication groove 78 that extends radially in a straight line through the center of the transport pad 63', as shown in Figures 6 and 7. A communication passage 66 formed vertically at the center of the transport pad 63' opens into this communication groove 78.
[0043] Therefore, the negative pressure generated by the suction source (not shown) is transmitted to each of the suction grooves 71, 72, and 73 via the communication passage 66 and communication groove 78 of the transport pad 63', and the wafer W is attracted by this negative pressure and held in place by the suction surface 63a' of the transport pad 63'.
[0044] Furthermore, in this alternative form of suction pad 63', as shown in Figure 8 (Figure 8 shows only one suction groove 73), a concave R-shaped chamfer (concave R chamfer) R1 and a convex R-shaped chamfer (convex R chamfer) R2 are formed on the concave and convex corner portions of each suction groove 71, 72, 73, respectively.
[0045] Therefore, in this alternative form of suction pad 63', when the wafer W on the chuck table 10 is held in suction, the grinding debris contained in the grinding fluid sucked up by each suction groove 71, 72, 73 does not accumulate in the concave and convex corners and dry out, thus preventing damage to the wafer W by this grinding debris.
[0046] Although the above has described a transport pad as one form of a suction table according to the present invention, the present invention also includes chuck tables that support wafers on a holding surface as its scope of application.
[0047] Furthermore, although the embodiments described above describe a grinding apparatus for grinding a wafer held on a chuck table, the transport pad or chuck table is not limited to a grinding apparatus. It may also be applied to polishing apparatuses, cutting apparatuses, and cutting apparatuses. In addition, in a CMP polishing apparatus that polishes a wafer by supplying a slurry containing free abrasive particles, the slurry is prevented from adhering to the transport pad, and the free abrasive particles contained in the slurry are prevented from scratching the wafer.
[0048] Furthermore, although wafers were described as an example of the workpiece held by the suction table in the above embodiments, the suction table according to the present invention is applicable to any workpiece other than wafers that is held by suction.
[0049] 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]
[0050] 1: Grinding device, 1A: Base, 2,3: Cassette, 5: Thickness measuring instrument 5a: First contact, 5b: Second contact, 10: Chuck table, 10A: Porous member, 10a: Holding surface, 11: Vertical movement mechanism, 12: Column, 13: Lifting plate, 14: Guide rail, 15: Ball screw shaft, 16: Electric motor, 17: Bracket, 20: Grinding unit, 21: Holder, 22: Spindle motor, 23: Spindle, 24: Mount, 25: Grinding wheel, 25a: Grinding stone, 30: Spinner cleaning means, 31: Spinner table, 32: Cleaning water nozzle, 33: Cover, 40: Robot, 41: Mounting part, 42: Holder, 43: Robot hand, 44: Horizontal movement mechanism, 45: Lifting mechanism, 50: First conveying means, 51: Rotating shaft, 52: Arm, 53: Conveying pad, 60: Second transport means, 61: Rotating shaft, 62: Arm, 63, 63': Transport pads, 63a, 63a': Suction surface, 64: Retaining ring, 65: Pin, 66: Connecting passage, 67: Piping, 67a, 67b: Branch pipes, 68: Lifting mechanism, 69: Air supply source, 70: Suction source, 71, 72, 73: Suction grooves, 73a: Bottom surface of suction groove, 73b, 73c: Side of suction groove, 74: Connecting passage, 75, 76, 77: Suction port, 78: Connecting passage, P1: Processing position, P2: Transfer position, R1: Concave R chamfer, R2: Convex R chamfer, V1, V2: Electromagnetic switch valve, W: Wafer
Claims
[Claim 1] A suction table that holds a workpiece by suction at the suction surface, The suction surface comprises a suction groove that opens in a ring shape, a suction port that opens at the bottom of the suction groove, and a communication passage that connects the suction port to a suction source. A suction table in which a chamfer is formed on the concave corner portion connecting the bottom surface of the suction groove and the side surface of the suction groove, and a chamfer is formed on the convex corner portion connecting the side surface of the connecting passage and the bottom surface of the suction groove.