JP2018129451A - Processing apparatus and unloading method of wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transfer a wafer without scratching a held surface of the wafer while suppressing adhesion of grinding waste.SOLUTION: A grinding device (1) includes carrying-out means (6) for carrying out a processed wafer (W) from a holding table (5). The carrying-out means includes a carrying-out pad (60) having a holding surface (64) for holding the wafer. The carrying-out pad includes a plurality of water discharge ports formed at the center of the holding surface toward the outer peripheral side and a plurality of water discharge grooves radially formed from the water discharge port toward the outer periphery to allow the water to flow therethrough. The water discharge groove has a structure in which the wafer and the holding surface are filled with water by not reaching the outer peripheral edge of the carrying-out pad, and after the wafer is separated from the holding table, the wafer is held by the attraction force acted by water.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a processing apparatus provided with a conveying means for conveying a wafer and a method for carrying out a wafer.

  In a semiconductor device manufacturing process, a wafer on which a plurality of devices such as ICs and LSIs are formed is ground to a predetermined thickness by grinding the back surface of the wafer with a grinding device before being divided into individual devices. In a grinding apparatus for grinding the back surface of a wafer, a wafer held on a chuck table is ground with a grinding wheel. The ground wafer is sucked and held by a transport pad provided in the grinding apparatus, and is transported from the chuck table to the spinner cleaning unit.

  In this way, when the wafer is transported by the transport pad, a situation may occur where the holding surface of the transport pad comes into contact with the held surface to be sucked and held, so that the held surface of the wafer is damaged. In order to solve such a problem, a method of conveying a wafer without damaging the held surface of the wafer has been proposed (see, for example, Patent Document 1). In the wafer transfer method described in Patent Document 1, a water layer is interposed in the gap between the held surface of the wafer and the holding surface of the transfer pad, and the held surface of the wafer is placed on the holding surface of the transfer pad by the surface tension of water. Holding and transporting the wafer.

JP 2009-252877 A

  In the wafer transfer method as described above, the wafer is held by interposing a water layer in the gap between the wafer holding surface and the holding surface of the transfer pad, and the grinding dust adheres to the wafer holding surface. This makes it difficult to damage the surface to be held of the wafer. On the other hand, in such a non-contact wafer conveyance method, it is required to convey the wafer without damaging the held surface of the wafer while further suppressing the adhesion of grinding dust.

  The present invention has been made in view of the above points, and provides a processing apparatus and a wafer unloading method capable of transporting a wafer to be held without damaging the surface while suppressing adhesion of grinding scraps. Is one of the purposes.

  A processing apparatus according to an aspect of the present invention includes a holding table that holds a wafer, a grinding unit that grinds the wafer held by the holding table with a grinding wheel, or a polishing unit that polishes the wafer held by the holding table with a polishing pad. A processing apparatus comprising: processing means including at least one; and unloading means for unloading the processed wafer from the holding table; the unloading means having a holding surface for holding the wafer in a plate shape; Elevating means for elevating and lowering the carry-out pad in a direction approaching and separating from the holding table, and the carry-out pad is formed at a center of the holding surface with a plurality of water outlets formed at an equal angle from the center toward the outer periphery, A plurality of water discharge grooves that radiate from the water discharge port toward the outer periphery and are recessed from the holding surface to distribute water, and the water discharge grooves reach the outer peripheral edge of the carry-out pad. After the wafer from the holding table filled with water and the wafer and the holding surface is spaced Ikoto holds the wafer by the suction force exerted by the water.

  According to this configuration, the wafer is held by the adsorption force acting by the water that has passed through the water discharge grooves formed radially from the water discharge port of the carry-out pad toward the outer periphery, and is carried out from the holding table. Can be carried out of the holding table in a wet state. Thereby, since the wafer can be held while flowing the water interposed between the holding surface and the wafer, it is possible to suppress the grinding dust from adhering. Further, since the wafer is held by the adsorption force acting by the water that has passed through the water discharge groove, the wafer can be held without contact with the holding surface of the carry-out pad, so that the held surface of the wafer is damaged. Can be prevented.

  According to the present invention, it is possible to carry the wafer without damaging the held surface of the wafer while suppressing the adhesion of grinding scraps.

It is a perspective view of the grinding device which is an example of the processing device concerning this embodiment. It is a perspective view which shows the external appearance of the carrying-out pad which the grinding apparatus which concerns on this Embodiment has. It is a perspective view for demonstrating the holding surface of the carrying-out pad which concerns on this Embodiment. It is a cross-sectional schematic diagram for demonstrating the internal structure of the carrying-out pad which concerns on this Embodiment. It is a cross-sectional schematic diagram for demonstrating the various processes at the time of carrying out a wafer with the carrying-out pad which concerns on this Embodiment. It is a perspective view for demonstrating the water flow between the holding surface of the carrying-out pad and the to-be-held surface of a wafer in the water supply process shown to FIG. 5A.

  Hereinafter, the grinding apparatus according to the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a grinding apparatus which is an example of a processing apparatus according to the present embodiment. Hereinafter, a case where a grinding apparatus is used as the processing apparatus according to the present embodiment will be described. However, the present invention is not limited to this, and the processing apparatus may be a polishing apparatus that polishes a wafer with a polishing pad. In FIG. 1, for convenience of explanation, a portion corresponding to an underwater moving means 43 described later is shown broken away.

  As shown in FIG. 1, the grinding apparatus 1 is configured to automatically perform a series of operations including a carry-in process, a grinding process, and a carry-out process on a wafer W that is a workpiece. The wafer W processed by the grinding device 1 is carried out to a cleaning device which is a separate device in a state of being stored in a cassette C2 in a shelf shape, and the front surface (upper surface) and the back surface (lower surface) are cleaned.

  The wafer W is formed in a substantially circular shape and is carried into the grinding apparatus 1 in a state of being stored in a shelf shape in the cassette C1. A protective tape T (see FIG. 4) having the same diameter as the wafer W is attached to the lower surface of the wafer W. The wafer W may be a plate-like member to be ground, may be a semiconductor wafer such as silicon or gallium arsenide, an optical device wafer such as ceramic, glass or sapphire, or an as-before-device pattern formation. A slice wafer may be used.

  A pair of cassettes C <b> 1 and C <b> 2 in which a plurality of wafers W are stored are disposed on the front side (X-axis direction side) of the base 10 of the grinding apparatus 1. Wafer W before grinding is stored in cassette C1, while wafer W after grinding is stored in cassette C2. A cassette robot 11 that takes out the wafer W from the cassette C1 is provided behind the cassette C1. Behind the cassette robot 11 is provided a positioning mechanism 14 for positioning the wafer W before processing.

  On the other hand, storage means 17 for storing the processed wafer W with respect to the cassette C2 is provided on the rear side and the lower side of the cassette C2. Between the positioning mechanism 14 and the storage means 17, a loading means 20 for loading the unprocessed wafer W into the holding table 5 is provided. Further, on the rear side of the storage means 17, an unloading means 6 for unloading the processed wafer W from the holding table 5 to the storage means 17 is provided.

  The cassette robot 11 is configured by providing a hand portion 13 at the tip of a robot arm 12 composed of a multi-node link. The cassette robot 11 transports the unprocessed wafer W from the cassette C1 to the positioning mechanism 14.

  The positioning mechanism 14 is configured by arranging a plurality of positioning pins 16 that can move forward and backward with respect to the center of the temporary table 15 around the temporary table 15. In the positioning mechanism 14, the center of the wafer W is positioned at the center of the temporary placement table 15 by the plurality of positioning pins 16 being abutted against the outer peripheral edge of the wafer W placed on the temporary placement table 15.

  In the carry-in means 20, the wafer W is lifted from the temporary placement table 15 by the carry-in pad 21, and the wafer W is carried into the holding table 5 by turning the carry-in pad 21 by the arm 22.

  In the unloading means 6, the wafer W is lifted from the holding table 5 by the unloading pad 60 and the lifting / lowering means 61, and the arm W connected to the unloading pad 60 and the like is turned by the turning means 62, whereby the wafer W is moved from the holding table 5. It is carried out. The unloaded wafer W is conveyed to the storage means 17. The detailed configuration of the carry-out means 6 will be described later.

  The storage means 17 includes a water tank 40 disposed on the front side of the unloading means 6, a cassette submersion means 41 for submerging the cassette C2 in the water in the water tank 40, and a rail 42 extending in the front-rear direction in the water tank 40. And an underwater moving means 43 for transporting the wafer W arranged on the rail 42 to the front side.

  The water tank 40 is provided integrally with the base 10 on the front side of the carry-out means 6. The water tank 40 is disposed on the lower side of the cassette C2. The water tank 40 has a shape opened to the upper side and contains a certain amount of water. The water tank 40 may be provided so as to be detachable from the base 10.

  The cassette submerging means 41 has a cassette stage 411 on which the cassette C2 is placed, and a cassette stage lifting / lowering means 412 that supports the cassette stage 411. The cassette stage 411 is disposed at a position corresponding to the opening of the water tank 40. The cassette stage raising / lowering means 412 is configured to be able to raise and lower the cassette stage 411 in a state where the cassette C2 is placed. As will be described in detail later, the cassette stage elevating / lowering means 412 lowers the cassette C2 into the water tank 40 and submerses it when the wafer W is stored by the underwater moving means 43.

  The rail 42 has a pair of rail members 421 that are arranged at regular intervals. These rail members 421 are disposed at positions where the rail members 421 are submerged in the water accommodated in the water tank 40. A plurality of wafer transfer surfaces 422 are formed on the upper surfaces of these rail members 421. These wafer transfer surfaces 422 are configured by forming a stepped portion on the rail member 421. These wafer transport surfaces 422 are configured to transport a plurality of wafers W having different dimensions. For example, the wafer transport surface 422 may be configured such that a wafer W having a large size in the upper stage (for example, 12 inches), a wafer W having a small dimension in the lower stage (for example, 6 inches), and a wafer W having a medium dimension in the middle stage (for example, 8 inches). Int) can be transported.

  The underwater moving means 43 includes a guide rail 431 extending in the front-rear direction and a slider 432 that can reciprocate along the guide rail 431. The slider 432 is provided with an arm 433 that protrudes to the inside of the apparatus, and an expansion / contraction member 434 configured to be expandable / contractible from the vicinity of the tip of the arm 433 downward. The telescopic member 434 is arranged at the center of the pair of rail members 421 in a top view, and is configured to be able to contact the rear end surface of the wafer W arranged on the rail members 421. The wafer W can be conveyed to the front side by moving the slider 432 to the front side in a state where the elastic member 434 is in contact with the rear end surface of the wafer W.

  A rectangular opening extending in the X-axis direction is formed on the upper surface of the base 10 on the rear side of the grinding apparatus 1. The opening is covered with a movable plate 23 that can move together with the holding table 5 and a bellows-shaped waterproof cover 24. Below the waterproof cover 24, ball screw type advance / retreat means (not shown) for moving the holding table 5 in the X-axis direction is provided. The holding table 5 is connected to table rotation means (not shown), and is configured to be rotatable about the center of the wafer W by driving the table rotation means. A holding surface 50 a that holds the lower surface of the wafer W is formed on the upper surface of the holding table 5.

  The column 25 erected from the rear portion of the base 10 is provided with a grinding feed means 26 for grinding and feeding the grinding means 30 in a direction (Z-axis direction) to approach and separate from the holding table 5. The grinding feed means 26 has a pair of guide rails 27 arranged in the column 25 and parallel to the Z-axis direction, and a motor-driven Z-axis table 28 slidably installed on the pair of guide rails 27. . Nut portions (not shown) are formed on the back side of the Z-axis table 28, and a ball screw 29 is screwed to these nut portions. The ball screw 29 is rotationally driven by a drive motor M connected to one end of the ball screw 29, whereby the grinding means 30 is moved along the guide rail 27 in the Z-axis direction.

  The grinding means 30 is attached to the front surface of the Z-axis table 28 via a housing 31 and is configured to rotate the grinding wheel 33 around the central axis by the spindle unit 32. The spindle unit 32 is a so-called air spindle, and rotatably supports the spindle shaft 34 via high-pressure air inside the casing.

  A mount 35 is connected to the tip of the spindle shaft 34, and a grinding wheel 33 provided with an annular grinding wheel 36 is attached to the mount 35. The grinding wheel 36 is constituted by, for example, combining diamond abrasive grains having a predetermined abrasive grain diameter with vitrified bonds. The grinding wheel 36 is not limited to this, and diamond abrasive grains may be formed by solidifying with a binder such as metal bond or resin bond. The grinding means 30 grinds the wafer W sucked and held by the holding table 5 with a grinding wheel 36.

  In such a grinding apparatus 1, the wafer W is transported from the cassette C <b> 1 to the positioning mechanism 14, and the wafer W is centered by the positioning mechanism 14. Next, the wafer W is loaded onto the holding table 5, and the holding table 5 is positioned at a processing position below the grinding means 30. At the processing position, the upper surface of the wafer W is ground to a desired thickness while measuring the thickness of the wafer W.

  After the grinding process, the holding table 5 is positioned in the vicinity of the unloading means 6. Then, the wafer W is unloaded from the holding table 5 by the unloading means 6. The wafer W is conveyed on a rail 42 included in the storage unit 17. Thereafter, the wafer W is transported to the cassette C2 along the rail 42 in the water tank 40 by the underwater moving means 43. When a predetermined number of wafers W are stored in the cassette C2, the cassette C2 is carried out to the cleaning device, and the internal wafer W is cleaned.

  In such a grinding apparatus 1, as a method for carrying out the wafer W to be carried out without damaging the held surface (grinding surface) of the wafer W after grinding, a gap between the held surface of the wafer W and the holding surface of the unloading pad 60. A method may be considered in which a water layer is interposed between the wafer W and the wafer W is carried out by the surface tension of the water. On the other hand, in such a non-contact wafer carrying-out method, it is required to carry out the wafer W without damaging the held surface of the wafer W while suppressing the adhesion of grinding dust with higher accuracy.

  The inventor pays attention to the strength of the adsorption force acting on the water interposed between the holding surface of the carry-out pad 60 and the held surface of the wafer W and the fluidity of the grinding waste, and holds the holding surface of the carry-out pad 60. It has been found that holding the wafer W while flowing water intervening between the wafer and the held surface of the wafer W contributes to improving the holding strength of the wafer W and suppressing adhesion of grinding scraps to the held surface. The present invention has been conceived.

  That is, the essence of the present invention is that the unloading means 6 for unloading the processed wafer W from the holding table 5 has the unloading pad 60, the water outlet formed in the central portion of the holding surface of the unloading pad 60, Adsorption force acting by the water filled in the gap between the holding surface of the carry-out pad and the held surface of the wafer W by providing a water discharge groove formed radially from the water discharge port toward the outer periphery. To carry out the wafer W from the holding table 5 while holding the wafer W.

  According to the grinding apparatus 1 according to the present invention, since the wafer W can be held while flowing the water interposed between the holding surface of the carry-out pad 60 and the held surface of the wafer W, the grinding dust adheres to the wafer W. Can be suppressed. In addition, since the wafer W is held by the suction force acting by the water flowing between the holding surface of the carry-out pad 60 and the held surface of the wafer W, the wafer W can be held without contact. It is possible to prevent the held surface of the wafer W from being damaged.

  Hereinafter, the structure of the carrying-out means 6 (carrying-out pad 60) which the grinding apparatus 1 which concerns on this Embodiment has is demonstrated with reference to FIGS. 1-3. FIG. 2 is a perspective view showing an appearance of the carry-out pad 60 included in the grinding apparatus 1 according to the present embodiment. FIG. 3 is a perspective view for explaining the holding surface 64 of the carry-out pad 60 included in the grinding apparatus 1 according to the present embodiment. In FIG. 2, for convenience of explanation, a part of the carry-out means 6 (lifting means 61) is shown in a simplified manner.

  As shown in FIG. 1, the carry-out means 6 includes a turning means 62 provided at the upper end of a support column erected on the base 10, an arm 63 extending in a horizontal direction from the peripheral surface of the turning means 62, and an arm Elevating means 61 connected to the tip of 63 and an unloading pad 60 supported on the lower end of the elevating means 61.

  The turning means 62 can turn the unloading pad 60 between a position where the processed wafer W is received from the holding table 5 and a position where the wafer W unloaded from the holding table 5 is transferred onto the rail 42 of the storage means 17. It is configured.

  The arm 63 is provided so as to extend from the peripheral surface of the turning means 62 toward the inside of the apparatus. The tip of the arm 63 is disposed in the upper region of the holding surface 50a of the holding table 5 disposed at the position where the wafer W after grinding is disposed, and in the upper region on the rear end side of the rail 42 of the storage means 17. Has a length to be

  The elevating means 61 is configured to be able to move up and down in a direction in which the carry-out pad 60 approaches and separates from the holding table 5. More specifically, the lifting / lowering means 61 has a height position for holding the wafer W on the holding table 5 and a height position for separating the wafer W from the holding table 5 by a certain distance and transporting the wafer W to the storage means 17. The carry-out pad 60 can be moved up and down.

  As shown in FIG. 2, the raising / lowering means 61 is connected by the center part of the upper surface of the carrying-out pad 60 which has a disk shape. A water supply source connection portion 631 and an air supply source connection portion 632 are provided on the upper surface of the arm 63 at a portion connected to the elevating means 61. A water supply source and an air supply source (not shown) are connected to the water supply source connection portion 631 and the air supply source connection portion 632, respectively, and water sprayed from the holding surface 64 (see FIG. 3) of the carry-out pad 60 Receive air supply. Inside the elevating / lowering means 61, a water supply pipe 633 that communicates the water supply source connection portion 631 with the water discharge port 642 and an air supply pipe 634 that communicates the air supply source connection portion 632 with the air outlet 632a are disposed. (See FIG. 4).

  As shown in FIG. 3, a holding surface 64 that has a plate shape and holds the wafer W is provided on the lower surface of the carry-out pad 60. A guide ring 65 is provided on the outer periphery of the carry-out pad 60. The guide ring 65 is attached to the carry-out pad 60 so that the lower end portion protrudes downward from the main body of the carry-out pad 60 (see FIG. 4). That is, the guide ring 65 is disposed so as to protrude from the holding surface 64 of the carry-out pad 60. The inner peripheral surface of the guide ring 65 that protrudes from the holding surface 64 constitutes an annular side wall that surrounds the outer peripheral edge of the holding surface 64.

  As shown in FIG. 3, a bottom surface portion 641 disposed on the same plane as the holding surface 64 is provided at the center of the holding surface 64. The bottom surface portion 641 has a generally circular shape when viewed from below, and constitutes a part of the holding surface 64. A water supply pipe 633 formed in the elevating / lowering means 61 is disposed above the bottom surface portion 641 (see FIG. 4). The bottom surface portion 641 is disposed so as to extend on a plane orthogonal to the traveling direction of water passing through the water supply pipe 633.

  A plurality of (three in the present embodiment) water outlets 642 that open toward the radially outer peripheral side of the holding surface 64 are formed above the bottom surface portion 641. These water outlets 642 are arranged at equal intervals from the center of the holding surface 64 (in this embodiment, the angle between the central portions of adjacent water outlets 642 is 120 degrees).

  A plurality (three in this embodiment) of water discharge grooves 643 extending radially from the water discharge port 642 toward the outer peripheral side in the radial direction of the holding surface 64 are formed on the outer peripheral side of each water discharge port 642. The water discharge groove 643 is formed so as to be recessed from the holding surface 64. In other words, the water discharge groove 643 is formed by forming a part of the holding surface 643 into a concave shape on the upper side. In the water discharge groove 643, one end on the center portion side of the holding surface 643 is connected to the water discharge port 642, and the other end on the outer peripheral portion side extends to the vicinity of the outer peripheral edge of the holding surface 64. Note that the other end of the water discharge groove 643 does not reach the outer peripheral edge of the holding surface 64.

  Further, the water discharge groove 643 has the most recessed one end on the water discharge port 642 side (center side of the holding surface 64), and gradually approaches the surface side of the holding surface 64 toward the other end on the outer peripheral side (FIG. 4). In other words, the water discharge groove 643 has the largest depth dimension at one end on the water discharge port 642 side, and gradually becomes shallower toward the other end on the outer peripheral side. That is, the upper surface 643a of the water discharge groove 643 constitutes an inclined surface that gradually decreases from the center of the holding surface 64 toward the outer peripheral side. The water outlet 642 is disposed at one end side of these water discharge grooves 643 in a state opened to the outer peripheral side.

  In addition, the part in which the water discharge groove 643 is not formed among the holding surfaces 64 comprises the flat surface. As described above, the outer peripheral end of the water discharge groove 643 does not reach the outer peripheral edge of the holding surface 64. For this reason, a flat surface arranged on the same plane as the holding surface 64 excluding the water discharge groove 643 is arranged in the vicinity of the outer peripheral edge of the holding surface 64. The flat surface of the holding surface 64 includes a bottom surface portion 641, three generally fan-shaped sections S <b> 1 to S <b> 3 disposed on the outer peripheral side of the bottom surface section 641, and a ring-shaped section disposed inside the guide ring 65. Configured (see FIG. 3).

  FIG. 4 is a schematic cross-sectional view for explaining the internal structure of the carry-out pad 60 according to the present embodiment. In FIG. 4, for convenience of explanation, the holding table 5 and the wafer W and the tape T placed thereon are shown. As shown in FIG. 4, a water supply pipe 633 communicating with the water supply source connection portion 631 is disposed inside the carry-out pad 60 and the lifting means 61. Similarly, an air supply pipe 634 that communicates with the air supply source connection portion 632 is disposed inside the carry-out pad 60 and the lifting means 61. The air supply pipe 634 is appropriately branched in the carry-out pad 60 and is configured to be able to release air to the lower surface of the holding surface 64.

  The unloading means 6 is configured to open the valve connected to the water supply source connection portion 631 and discharge water from the water outlet 642 when unloading the processed wafer W from the holding table 5. The water discharged from the water discharge port 642 is discharged radially through the water discharge groove 643. By discharging water in this manner with the holding surface 64 of the carry-out pad 60 approaching the held surface W1 of the wafer W on the holding table 5, a water flow is generated between the held surface W1 and the holding surface 64. . The water flow generated in this way generates an adsorption force for the wafer W on the holding table 5. The wafer W can be held on the holding surface 64 of the carry-out pad 60 by releasing the suction holding force of the holding table 5 in a state where the suction force is generated in this way.

  On the other hand, in the unloading means 6, when the wafer W held on the holding surface 64 of the unloading pad 60 is transferred onto the rail 42 of the storage means 17, the valve connected to the air supply source connection portion 632 is opened and held. Air is discharged from an air discharge port 632a (see FIG. 3) of the surface 64. Thereby, it is possible to release the water flow adsorbing force generated between the holding surface 64 of the carry-out pad 60 and the held surface W <b> 1 of the wafer W, and transfer the wafer W onto the rail 42.

  Next, a method for carrying out the wafer W in the grinding apparatus 1 having the above configuration will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view for explaining various processes when the wafer W is carried out by the carry-out pad 60 according to the present embodiment. In FIG. 5, for convenience of explanation, the air supply source connection portion 632 and the air supply pipe 634 provided in the carry-out pad 60 and the lifting / lowering means 61 are omitted (see FIG. 4).

  FIG. 5A is an explanatory diagram of a process of supplying water to the holding surface 64 of the carry-out pad 60 (hereinafter referred to as “water supply process”). In addition, a water supply process can also be called a preparation process. In this water supply step, after the carry-out pad 60 is positioned on the holding table 5, the carry-out pad 60 is brought close to the holding table 5 by the lifting means 61 to a predetermined position. At this time, the holding surface 64 of the carry-out pad 60 faces the held surface W1 of the wafer W but is not in contact with the wafer W. Further, the guide ring 65 provided on the outer peripheral portion of the carry-out pad 60 is disposed at a position surrounding the outer peripheral region of the wafer W and the tape T placed on the holding table 5. Then, by opening the valve B connected to the water supply source connection portion 631 in a state where the carry-out pad 60 is brought close to the holding table 5 to a predetermined position, the holding surface of the carry-out pad 60 via the water supply pipe 633 Water is supplied to a gap between the holding surface W1 of the wafer W on the holding table 5 and the held surface W1.

  Here, the behavior (water flow) of the water supplied to the gap between the holding surface 64 and the held surface W1 in this water supply step will be described with reference to FIG. FIG. 6 is a perspective view for explaining the water flow between the holding surface 64 of the carry-out pad 60 and the held surface W1 of the wafer W in the water supply step shown in FIG. 5A. The water supplied from the water supply pipe 633 comes into contact with the back surface of the bottom surface portion 641 and changes its direction, and is discharged from the water outlet 642 to the outer peripheral side in the radial direction of the holding surface 64.

  The water discharged from the water discharge port 642 flows along the water discharge groove 643 toward the radially outer peripheral side of the carry-out pad 60 (arrow A shown in FIG. 6). At this time, the upper surface 643a of the water discharge groove 643 is closer to the holding surface 64 toward the outer peripheral side in the radial direction of the holding surface 64 (see FIG. 5A). That is, the depth of the water discharge groove 643 becomes shallower toward the radially outer peripheral side. Since the depth becomes shallower than the amount of water flowing through the water discharge groove 642, water flows from the water discharge groove 643 to the holding surface 64 toward the outer side in the radial direction. At this time, the flow velocity of the water flow in the water discharge groove 643 is slowed toward the outside of the water discharge groove 643 and flows out to the holding surface 64 to form a water layer on the holding surface 64 and the upper surface of the wafer. (Arrow B shown in FIG. 6). Further, the other end on the outer peripheral side of the water discharge groove 643 does not reach the outer peripheral edge of the holding surface 64. For this reason, the flow rate of the formed water layer can be sufficiently slowed down. The water discharged into the water discharge groove 643 collides with the inner wall surface of the guide ring 65 in a state where the flow velocity is sufficiently slow, and flows out (flows down) along the inner wall surface. The water layer exerts surface tension on the holding surface 64 and the upper surface of the wafer W by sufficiently slowing the flow velocity, and an adsorption force that adsorbs the wafer W toward the holding surface 64 acts.

  The water that flows out to the outer side in the circumferential direction of the water discharge groove 643 collides with the water that flows out from the adjacent water discharge groove 643 to further reduce the flow rate and stay in the sections S1 to S3, and then along the inner wall surface of the guide ring 65. It flows out (flows down). Further, the water that has flowed out in the circumferential direction from the water discharge groove 643 in the vicinity of the water discharge port 642 wraps around the center of the holding surface 64 to form a water flow that flows into the water discharge groove 643 again (water flow indicated by the arrow C shown in FIG. 6).

  By passing water through the water discharge groove 643 through the gap between the holding surface 64 and the held surface W1 in this way, the flow velocity of the water flow in the water discharge groove 643 is greater in the outer peripheral portion than in the vicinity of the water discharge port 642. Negative pressure is generated in the vicinity of the water outlet 642 that is slow and has a fast water flow (Bernoulli's theorem). For this reason, a suction force that sucks the wafer W toward the holding surface 64 acts. Further, the water supplied from the water discharge groove 643 wraps around the sections S1 to S3 between the adjacent water discharge grooves 643, and the entire gap between the holding surface 64 and the held surface W1 is filled with water. For this reason, if the water flow is not greatly changed by stopping the supply of water or the like, a water layer having a gentle water flow is formed, and the surface is filled with water (water layer) filled in portions corresponding to these sections S1 to S3. The tension acts, and an attracting force that attracts the wafer W toward the holding surface 64 acts. In this water supply step, when the water filled in the gap between the holding surface 64 and the held surface W1 flows out (flows down) from the inner wall surface of the guide ring 65, the remaining grinding on the held surface W1 or the like Waste can be discharged to the lower side of the holding table 5.

  In the water supply process, after generating an adsorption force to adsorb the wafer W, the process proceeds to the process shown in FIG. 5B. FIG. 5B is an explanatory diagram of a process of separating the wafer W placed on the holding table 5 from the holding table 5 and holding it with the carry-out pad 60 (hereinafter referred to as “wafer holding process”). In this wafer holding step, the suction force acting on the holding surface 50a of the holding table 5 is stopped and the holding surface 50a is removed from the holding surface 50a in a state where the suction force generated by the water supplied to the holding surface 64 is generated as described above. Release fluid (water or air). As a result, the wafer W is released from the suction force of the holding surface 50a, while being separated from the holding table 5 and held by the suction force of the carry-out pad 60. In this wafer holding step, the grinding dust clogged in the holding surface 50a is discharged from the holding surface 50a and flows out of the holding table 5 together with water.

  In the wafer holding step, the wafer W is separated from the holding table 5 and held by the carry-out pad 60, and then the process proceeds to the step shown in FIG. 5C. FIG. 5C is an explanatory diagram of a step of carrying out the wafer W held by the holding surface 64 of the carry-out pad 60 (hereinafter referred to as “wafer carry-out step”). In this wafer carry-out process, after the wafer W is adsorbed by the carry-out pad 60 in the wafer holding process, the valve B connected to the water supply source connection portion 631 is closed. In this case, the water flow through the water discharge groove 643 is stopped, but the water that has entered the gap between the holding surface 64 and the held surface W1 does not flow out of the gap. For this reason, a thin water layer WL is formed in the gap between the holding surface 64 and the held surface W1. In the wafer unloading process, the wafer W is held by the surface tension generated in the water layer WL.

  In the wafer unloading step, the unloading pad 60 is lifted by the lifting / lowering means 61 while the wafer W is held, and is swung to the storage means 17 side by the swiveling means 62. When the carry-out pad 60 turns to the rail 42 of the storage means 17, the carry-out pad 60 is lowered by the lifting means 61. Then, air is discharged to the holding surface 64 via the air supply pipe 634 (see FIG. 4) formed on the carry-out pad 60, and the wafer W is placed on the rail 42. At this time, the wafer W is placed on the rail 42 (wafer transport surface 422) while being submerged in the water in the water tank 40.

  When the wafer W is transferred onto the rail 42, the cassette submerging means 41 of the storage means 17 submerges the cassette C2 in the water tank 40. On the other hand, the underwater moving means 43 extends the elastic member 434 to a position where it contacts the rear end of the wafer W on the rail 42 and moves the slider 432 forward. As a result, the wafer W is pushed forward on the wafer transfer surface 422 of the rail 42 and stored in the submerged cassette C2. When a predetermined number of wafers W are thus stored in the cassette C2, the cassette submerging means 41 raises the cassette C2 from the water in the water tank 40. And the wafer W is carried out to the washing | cleaning apparatus which is another apparatus in the state accommodated in cassette C2.

  As described above, according to the grinding apparatus 1 according to the present embodiment, when the wafer W after grinding is carried out from the holding table 5, the water discharge port 642 of the holding surface 64 of the carry-out pad 60 is directed toward the outer periphery. The wafer W is carried out from the holding table 5 in a state where the wafer W is held by the adsorption force of the water flow generated by passing water through the radially formed water discharge grooves 643. For this reason, since the wafer W is held by the suction force generated by the water flow that has passed through the water discharge groove 643 of the holding surface 64 of the carry-out pad 60, the wafer W can be held on the carry-out pad 60 in a non-contact manner. Further, it is possible to prevent the held surface W1 of the wafer W from being damaged. Further, since the wafer W can be held while flowing the water interposed between the holding surface 64 of the carry-out pad 60 and the held surface W1 of the wafer W, the water W is held between the holding surface 64 and the held surface W1. It is possible to avoid the stagnation of existing grinding scraps, and it is possible to suppress the grinding scraps from adhering to the upper surface (held surface W1) of the wafer W.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above embodiment, in the wafer carry-out process shown in FIG. 5C, water flow to the water discharge groove 643 is stopped, and the water layer between the holding surface 64 of the carry-out pad 60 and the held surface W1 of the wafer W. The case where the wafer W is held by the surface tension due to is described. However, in the wafer unloading step, the wafer W may be held by using the adsorption force generated by the water flow that has passed through the water discharge groove 643, as in the wafer holding step. In this case, even in the wafer unloading process, the fluidity of water interposed between the holding surface 64 of the unloading pad 60 and the held surface W1 of the wafer W can be secured, and the grinding debris can be further removed from the upper surface (covered surface) of the wafer W. Adhesion to the holding surface W1) can be suppressed.

  As described above, the present invention has an effect that it can be conveyed without damaging the surface to be held of the wafer while suppressing the adhesion of the grinding dust, and in particular, grinding and polishing for the wafer. It is useful for any processing apparatus that performs processing.

DESCRIPTION OF SYMBOLS 1 Grinding device 17 Storage means 42 Rail 30 Grinding means 36 Grinding wheel 5 Holding table 6 Unloading means 60 Unloading pad 61 Lifting means 62 Turning means 63 Arm 64 Holding surface 641 Bottom surface 642 Water outlet 643 Water discharge groove 65 Guide ring W Wafer

Claims (2)

A holding table for holding the wafer, and a processing means including at least one of a grinding means for grinding the wafer held by the holding table with a grinding wheel or a polishing means for polishing the wafer held by the holding table with a polishing pad; An unloading means for unloading the processed wafer from the holding table,
The unloading means is
A plate-like carry-out pad having a holding surface for holding the wafer, and lifting means for raising and lowering the carry-out pad in a direction approaching and separating from the holding table,
The carry-out pad has a plurality of water outlets formed at equal angles from the center toward the outer periphery in the center of the holding surface, and a plurality of water outlets that radiate from the water outlet to the outer periphery and are recessed from the holding surface to circulate water. And a water ditch,
The water discharge groove is a process for holding the wafer with an adsorption force acting by water after the wafer and the holding surface are filled with water by not reaching the outer peripheral edge of the carry-out pad and the wafer is separated from the holding table. apparatus. A wafer unloading method for unloading a wafer held by the holding table from the holding table in the processing apparatus according to claim 1,
A preparation step of lowering the carry-out pad to form a gap between the holding surface and the upper surface of the wafer to discharge water from the water discharge port and pass the water through the water discharge groove;
After the preparation step, a holding step in which the discharge pad holds the wafer by a flow of water ejected from the holding table to separate the wafer and the water flowed through the water discharge groove;
A method for carrying out the wafer, comprising: a step of carrying out the wafer by raising the carry-out pad after the holding step.

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