Wafer transfer apparatus

Abstract

To stably hold a wafer by a suction pad.SOLUTION: The transfer mechanism (38) includes a suction pad (42) for sucking and holding the upper surface side of a wafer (200) having a circular recess (207) formed at the center, an annular projection (208) formed outside the circular recess, and a chamfered portion (206) at the outer peripheral edge by a suction surface (61). The suction pad includes a seal portion (83) that comes into contact with an outer peripheral portion of the wafer and forms a columnar space (209) between the suction surface and an upper surface of the wafer, a tubular member (63) that supplies water to the space to form a water film (209), and an annular rib (81) that prevents a side slip of the wafer sucked and held by the suction surface. The seal portion is formed in a closed loop shape in accordance with the outer peripheral portion of the wafer. The side slip preventing part is disposed so as to bring the seal part into surface contact with the chamfered part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a wafer transport device equipped with a suction pad for holding a wafer. [Background technology]

[0002] Patent Documents 1 and 2 disclose grinding devices that grind wafers with a grinding wheel. The grinding devices of Patent Documents 1 and 2 include a transfer device that transfers the ground wafer from the chuck table.

[0003] The wafer in Patent Document 2 has a circular recess formed in the center and an annular protrusion formed outside the circular recess. The transport device in Patent Document 2 holds the wafer by forming a water film between the underside of the suction pad and the bottom of the circular recess of the wafer, and transports the wafer to the cleaning unit while keeping the bottom of the circular recess dry. In the cleaning unit, a cleaning brush that rotates around the axis of the suction pad comes into contact with the underside of the wafer to clean the underside.

[0004] Furthermore, Patent Document 2 discloses a suction pad with a protrusion that comes into contact with the outer surface of a wafer. The protrusion comes into contact with the outer surface of the wafer held by the suction pad, thereby preventing the wafer from shifting sideways relative to the suction pad. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-208593 [Patent Document 2] Japanese Patent Publication No. 2022-135901 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 2, the outer surface of the wafer is not chamfered but is formed into a rectangular cross section. Therefore, if a wafer having a chamfered portion on its outer surface is held by the suction pad with the convex portion of Patent Document 2, the O-ring provided on the convex portion of Patent Document 2 and the chamfered portion will come into linear contact, reducing the contact area or causing the O-ring and the chamfered portion to come into no contact. This causes the O-ring to be unable to fully seal, making it difficult to adjust the pressure in the space where the water film is formed, and making it impossible for the suction pad to stably hold the wafer.

[0007] The present invention has been made in view of the above points, and one of its objects is to provide a wafer transport device that can stably hold a wafer with a suction pad. [Means for solving the problem]

[0008] A wafer transport device according to one embodiment of the present invention is a wafer transport device comprising: a suction pad that uses a suction surface to suction and hold the top side of a wafer having a circular recess in the center, an annular protrusion outside the circular recess, and a chamfered outer periphery; and a moving mechanism that moves the suction pad, for transporting the wafer. The suction pad comprises: a seal portion that contacts the outer periphery of the wafer to form a cylindrical space between the suction surface and the top side of the wafer; a water film supply portion that supplies water to the cylindrical space to form a water film on the top surface of the wafer; a pressure adjustment portion that adjusts the pressure of the space with the water film formed to atmospheric pressure; and a skid prevention portion that prevents skid of the wafer held by suction on the suction surface, the seal portion being formed in a closed loop shape corresponding to the outer periphery of the wafer, and the skid prevention portion being arranged so that the seal portion is in surface contact with the chamfered portion or the inner periphery of the circular recess.

[0009] Furthermore, one aspect of the present invention provides a wafer transport device that transports a wafer, the wafer transport device comprising: a suction pad that suction-holds the upper surface of a wafer with a suction surface, the upper surface having a circular recess formed in the center, an annular protrusion formed around the circular recess, and a chamfered outer periphery; and a moving mechanism that moves the suction pad, the suction pad comprising: a seal portion that contacts the outer periphery of the wafer to form a cylindrical space between the suction surface and the upper surface of the wafer; a water film supply portion that supplies water to the cylindrical space to form a water film on the upper surface of the wafer; a pressure adjustment portion that adjusts the pressure of the space with the water film formed to atmospheric pressure; and a lateral slip prevention portion that prevents lateral slip of the wafer held by suction on the suction surface, the seal portion being formed in a closed loop shape according to the outer periphery of the wafer and making surface contact with the tip surface of the annular protrusion. [Effects of the Invention]

[0010] According to the present invention, the anti-slip portion prevents the wafer held by suction by the suction pad from sliding sideways, while the seal portion comes into surface contact with the chamfered portion of the wafer, the inner peripheral surface of the circular recess, and the tip surface of the annular protrusion, so that the seal portion can exhibit good sealing performance with the wafer. This makes it possible to maintain good pressure in the space when a water film is formed on the wafer having the chamfered portion and circular recess, and to stably hold the wafer with the suction pad. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view of a grinding device according to a first embodiment. [Figure 2] FIG. 10 is a cross-sectional view of the wafer after grinding. [Figure 3] 2 is a partial cross-sectional view of a carry-out mechanism and its periphery according to the first embodiment. FIG. [Figure 4] FIG. 4 is a partially enlarged view of FIG. [Figure 5] 5 is a cross-sectional view similar to FIG. 4, illustrating a state in which the wafer is cleaned during transfer. [Figure 6] 5 is a partially enlarged view similar to FIG. 4 of the ejection mechanism according to the second embodiment. FIG. [Figure 7]10 is a partially enlarged view similar to FIG. 4 of a carry-out mechanism according to a third embodiment. FIG. [Figure 8] 10 is a partially enlarged view similar to FIG. 4 of a carry-out mechanism according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a grinding apparatus to which a wafer transport device according to an embodiment is applied will be described with reference to the accompanying drawings. Note that the grinding apparatus according to the embodiment is not limited to the configuration shown below and can be modified as appropriate.

[0013] [First embodiment] FIG. 1 is a perspective view of a grinding device according to a first embodiment. First, the overall configuration of the grinding device 1 will be described with reference to FIG. 1. The X-axis, Y-axis, and Z-axis directions shown in FIG. 1 are perpendicular to one another. The X-axis and Y-axis directions are substantially horizontal, and the Z-axis direction is the up-down direction (vertical direction). In addition, in the following drawings, the front side in the X-axis direction will be referred to as the +X side, the rear side as the -X side, the right side in the Y-axis direction as the +Y side, the left side as the -Y side, and the upper side in the Z-axis direction as the +Z side and the lower side as the -Z side.

[0014] The grinding apparatus 1 shown in Fig. 1 is an example of a processing apparatus to which the present invention is applied. Note that the present invention is not limited to the grinding apparatus 1, and can also be applied to other processing apparatuses equipped with various tables, processing mechanisms, transport mechanisms, etc. The grinding apparatus 1 is configured to perform a series of processes on a wafer 200, including a load process, a grinding process, a cleaning process, and a load process.

[0015] As shown in FIG. 1, the grinding apparatus 1 is an example of a processing apparatus equipped with a wafer transfer apparatus according to the embodiment, and is an apparatus for grinding a wafer 200.

[0016] 2 is a cross-sectional view of a wafer after grinding. Wafer 200 is an example of a plate-shaped workpiece, and has a front surface 201 and a back surface 202. Wafer 200, which is the object of grinding, has front surface 201 and back surface 202, and examples thereof include a disk-shaped semiconductor wafer or optical device wafer whose base material is silicon, sapphire, gallium, or the like.

[0017] The wafer 200 includes a device region 203 and a peripheral excess region 204 surrounding the device region 203. A plurality of devices (not shown) are formed in the device region 203 on the front surface 201 of the wafer 200, and are protected by a protective tape 205 attached to the front surface 201. A chamfered portion 206 having an arc-shaped cross section is formed on the outer periphery of the wafer 200, extending from the front surface 201 to the back surface 202. The chamfered portion 206 may be a C-chamfer or an R-chamfer.

[0018] After the grinding process, the wafer 200 has the back surface 202 side of the device region 203 thinned, and a circular recess 207 is formed in the center of the back surface 202. Furthermore, in the wafer 200 after the grinding process, the peripheral excess region 204 is not thinned, and an annular protrusion 208 is formed outside the circular recess 207.

[0019] 1, the grinding apparatus 1 will now be described. In the grinding apparatus 1, the wafers 200 stored in cassettes 22 and 23 on the first apparatus base 21 are transported by the robot 24 to the temporary placement mechanism 26 and aligned. Thereafter, the wafers 200 temporarily placed on the temporary placement mechanism 26 are transported by the carry-in mechanism 27 to the chuck table 30 provided on the second apparatus base 28 and held on its holding surface 31.

[0020] Furthermore, the wafer 200 held on the holding surface 31 is ground by a grinding mechanism 35 that is raised and lowered by a grinding feed mechanism 34 provided on a column 33. At this time, the thickness of the wafer 200 is measured by a thickness measuring device 36.

[0021] The ground wafer 200 is transferred (transferred) from the chuck table 30 by a transfer mechanism 38, which is an example of a wafer transfer device according to the embodiment, and is transferred to a single-wafer spinner cleaning mechanism 39 for cleaning. The cleaned wafer 200 is transferred into the cassettes 22 and 23 by a robot 24.

[0022] The chuck table 30 is provided with a circular porous plate 40, the upper surface of which forms the holding surface 31. The porous plate 40 is made of a porous material such as ceramics, and has fine pores formed throughout. The porous plate 40, including the holding surface 31, is connected to a table suction source 41, and the wafer 200 is sucked and held by the negative pressure of the table suction source 41.

[0023] Next, the carry-out mechanism 38 of the first embodiment will be described. The carry-out mechanism 38 includes a suction pad 42 that suction-holds the wafer 200, and a moving mechanism 43 that moves the suction pad 42. Below, the moving mechanism 43 and the suction pad 42 will be described in that order, with reference to FIG. 3 as well.

[0024] 3 is a partial cross-sectional view of the discharge mechanism and its periphery according to the first embodiment. As shown in FIG. 3, the movement mechanism 43 includes an arm 45 that suspends the suction pad 42, a rotating pillar 46 that extends in the Z-axis direction, and a drive mechanism 47 that is connected to the rotating pillar 46. The base end of the arm 45 is connected to the upper end of the rotating pillar 46. The drive mechanism 47 moves the rotating pillar 46 together with the arm 45 and the suction pad 42.

[0025] The drive mechanism 47 includes a column 48 erected on the first device base 21 (see FIG. 1), a ball screw 49 provided on the column 48, and a guide rail 50 disposed parallel to the ball screw 49. The drive mechanism 47 also includes a motor 51 that rotates the ball screw 49, an encoder 52 that detects the amount of rotation of the ball screw 49 (for example, the number of rotations and the rotation angle), and a nut 53 that threadably engages with the ball screw 49. A rotating pillar 46 is slidably installed on the guide rail 50. The rotating pillar 46 is also connected to the nut 53.

[0026] In the drive mechanism 47, the motor 51 rotates the ball screw 49 around its axis, thereby moving the rotating column 46 in the Z-axis direction along the guide rail 50. Then, by moving the rotating column 46 in the Z-axis direction, the arm 45 connected to the rotating column 46 and the suction pad 42 suspended by the arm 45 are moved in the Z-axis direction. At this time, the encoder 52 recognizes the amount of rotation of the ball screw 49 and, based on the recognition result, detects the height position of the suction pad 42 moved in the Z-axis direction.

[0027] The movement mechanism 43 further includes a rotation motor (not shown), and is provided so that the arm 45 can be rotated via the rotation motor about a central axis that is parallel to the Z-axis direction and passes through the center of the rotation column 46. As described above, the movement mechanism 43 moves the arm 45 up and down and rotates it, thereby moving the suction pad 42 and adjusting the height and horizontal position of the suction pad 42.

[0028] A plurality of bolts 55 are erected on the upper surface of the suction pad 42. In this embodiment, three bolts 55 (one not shown) are arranged at 120° intervals around the center of the circular suction pad 42 when viewed from above, and each bolt 55 passes through a through-hole 56 formed on the tip side of the arm 45.

[0029] The bolt 55 has a shaft 57 having a diameter slightly smaller than that of the through-hole 56, and a head 58 formed at the upper end of the shaft 57. The shaft 57 passes through the through-hole 56 and is loosely fitted in the through-hole 56. The lower end of the shaft 57 is connected to the upper surface of the suction pad 42. The head 58 has a diameter larger than that of the through-hole 56, and limits the downward range of the bolt 55.

[0030] The bolt 55 also has a spring 60 as a shock absorbing member around the shaft 57. The upper end of the spring 60 is in contact with the lower surface of the arm 45, while the lower end of the spring 60 is in contact with the upper surface of the suction pad 42. The spring 60 biases the arm 45 and the suction pad 42 in directions away from each other. Therefore, the arm 45 is provided so as to be able to suspend the suction pad 42 while absorbing shocks applied to the suction pad 42 via the spring 60, the bolt 55, etc.

[0031] The suction pad 42 suction-holds the back surface 202, which is the upper surface of the wafer 200 placed on the holding surface 31 of the chuck table 30. The suction pad 42 is provided in a roughly circular disk shape, and its lower surface serves as a suction surface 61 that suction-holds the wafer 200. The suction pad 42 suction-holds the back surface 202, which is the upper surface of the wafer 200, with the suction surface 61.

[0032] A tubular member 63 parallel to the Z-axis direction is connected to the center of the upper surface of the suction pad 42, passing through a hole 62 in the arm 45. A flow path 64 is formed so as to pass through the tubular member 63 and the suction pad 42. The lower end of the flow path 64 is connected to an opening 65 formed in the center of the suction surface 61. The upper end of the flow path 64 is connected to a branch flow path 66, one of which is connected to a suction source 69 via a suction valve 68.

[0033] The suction valve 68 is disposed between the branched portion of the branch flow path 66 and the suction source 69. By opening the suction valve 68, the opening 65 of the suction surface 61 can be connected to the suction source 69 via the branch flow path 66 and the flow path 64.

[0034] One of the branched flow paths 66 is connected to a water supply source 73 via a water supply valve 72. Therefore, by opening the water supply valve 72, the opening 65 of the suction surface 61 can be connected to the water supply source 73 via the branched flow path 66 and the flow path 64.

[0035] A first through-hole 74 is formed near the outer periphery of the suction pad 42, extending through the suction pad 42. The lower end of the first through-hole 74 is formed to open to the suction surface 61. The upper end of the first through-hole 74 is connected to a check valve 76 formed on the upper surface of the suction pad 42.

[0036] Further, a second through-hole 77 is formed to pass through the suction pad 42. The lower end of the second through-hole 77 is formed to open to the suction surface 61. The upper end of the second through-hole 77 is connected to a shock absorber 78 provided on the upper surface of the suction pad 42.

[0037] The suction pad 42 is formed with a diameter dimension larger than the wafer 200 to be suction-held. An annular recess 80 is formed on the suction surface 61 of the suction pad 42 so that the annular protrusion 208 of the wafer 200 can be inserted from below and received therein. In other words, by forming the annular recess 80 on the suction surface 61, the suction pad 42 is provided with an annular rib 81 formed on the outside of the annular recess 80 and an insertion portion 82 that is circular in top view and formed inside the annular recess 80 and protrudes downward.

[0038] FIG. 4 is a partially enlarged view of FIG. 3. As shown in FIG. 4, the inner peripheral surface of the annular rib 81 (the left surface in FIG. 3) is inclined relative to the vertical direction so that the thickness decreases toward the tip (lower end) of the annular rib 81. The suction pad 42 includes a seal portion 83 attached to the inner side of the annular rib 81, which is the inner side of the annular recess 80. The seal portion 83 is formed in a closed loop (ring shape) according to the outer peripheral portion of the wafer 200 and is in surface contact with the outer peripheral portion. Specifically, the seal portion 83 is disposed along the bottom side (upper surface side) of the annular recess 80 and the inner peripheral surface side of the annular rib 81, and is in surface contact with the upper end surface (tip surface) of the annular protrusion 208 of the wafer 200 and approximately the upper half of the chamfered portion 206. When the suction pad 42 holds the wafer 200 by suction, only the seal portion 83 comes into contact with the wafer 200. The seal portion 83 is made of a sponge or the like that exhibits sealing properties (liquid-tightness) against the wafer 200 that comes into contact with it.

[0039] With the wafer 200 held by suction on the suction pad 42, the annular rib 81 is disposed to surround the outer periphery of the wafer 200, and a seal portion 83 is interposed between the annular rib 81 and the outer periphery of the wafer 200. Therefore, the lateral movement of the wafer 200 held by suction on the suction pad 42 (directions parallel to the XY plane) is restricted by the annular rib 81 and the seal portion 83. In other words, the annular rib 81 functions as a lateral slip prevention portion that prevents lateral slip of the wafer 200 held by suction on the suction surface 61, and is disposed so that the seal portion 83 is in surface contact with the chamfered portion 206 of the wafer 200.

[0040] With the seal portion 83 of the suction pad 42 in surface contact with the wafer 200, a space 209 is formed between the suction surface 61 and the circular recess 207 that forms the upper surface of the wafer 200 (see FIG. 4). This space 209 is formed in a cylindrical shape with a diameter dimension considerably larger than its vertical height, and a predetermined level of closure is maintained by the seal portion 83. The insertion portion 82 is inserted into the space 209 from above, and the volume of the space 209 is reduced by the insertion portion 82. The suction surface 61 may be dome-shaped with its center protruding downward, and the base of the dome shape may be used as a skid prevention part, with the seal part 83 located outside the skid prevention part.

[0041] The discharge mechanism 38 also has a control unit 85 for controlling the discharge mechanism 38. The control unit 85 includes a CPU that performs calculations according to a control program, a storage medium such as a memory, and the like. The control unit 85 executes various processes and comprehensively controls each component of the discharge mechanism 38. The control unit 85 may also be configured to control the overall configuration of the grinding apparatus 1 including the discharge mechanism 38.

[0042] Next, a description will be given of a method for transporting the wafer 200 by the above-mentioned unloading mechanism 38. The transport of the wafer 200 by the unloading mechanism 38 is carried out after grinding of the wafer 200 using the grinding mechanism 35 (see FIG. 1) is completed.

[0043] After grinding of the wafer 200 is completed, the chuck table 30 holding the wafer 200 is moved by a moving mechanism (not shown) from below the grinding mechanism 35 in the -Y direction close to the carry-out mechanism 38. Thereafter, the moving mechanism 43 in the carry-out mechanism 38 pivots the rotating column 46 and the arm 45, and the suction pad 42 is positioned above the wafer 200 held on the holding surface 31 of the chuck table 30.

[0044] Next, the drive mechanism 47 of the moving mechanism 43 is driven to lower the arm 45 and the suction pad 42, causing the seal portion 83 of the suction pad 42 to contact the outer periphery of the wafer 200. As a result, a cylindrical space 209 is formed that is surrounded by the suction surface 61 of the suction pad 42 and the circular recess 207 of the wafer 200 and is closed by the seal portion 83.

[0045] Next, with the suction valve 68 closed, the water supply valve 72 is controlled to open, and water is supplied to the space 209 through the branch flow path 66 communicating with the water supply source 73 and the flow path 64 of the tubular member 63. In the space 209, the water supplied from the flow path 64 accumulates, and a water film 210 is formed in the circular recess 207 that forms the upper surface of the wafer 200. Due to the surface tension of the water film 210 formed in the space 209, the wafer 200 held on the chuck table 30 is sucked and held on the suction surface 61 of the suction pad 42.

[0046] Here, in the suction pad 42, a water film supply section is formed by a tubular member 63 having a flow path 64, and water is supplied to a cylindrical space 209 by the flow path 64 of the tubular member 63, thereby forming a water film 210 in a circular recess 207 which forms the upper surface of the wafer 200.

[0047] After the water film 210 is formed by supplying water into the space 209, the suction valve 68 is controlled to open while the water supply valve 72 is closed, and the water in the space 209 is sucked through the branch flow path 66 communicating with the suction source 69 and the flow path 64 of the tubular member 63. As a result, the pressure in the space 209 with the water film 210 formed is adjusted to atmospheric pressure, and the pressure inside and outside the space 209 becomes approximately the same.

[0048] Here, in the suction pad 42, a pressure adjusting section is formed by a tubular member 63 having a flow path 64, and the space 209 in the state where the water film 210 is formed is set to atmospheric pressure by the flow path 64 of the tubular member 63. Note that if the water pressure in the space 209 exceeds atmospheric pressure, the check valve 76 may be opened to discharge water from the space 209 to the outside.

[0049] With the wafer 200 on the chuck table 30 held by the suction pad 42 as described above, the suction by the table suction source 41 is stopped, and the wafer 200 is released from the holding surface 31 of the chuck table 30. Next, the moving mechanism 43 is driven to raise the suction pad 42 holding the wafer 200, and the wafer 200 is moved upwardly away from the holding surface 31 of the chuck table 30. Thereafter, the moving mechanism 43 pivots the rotating column 46 and the arm 45, and the suction pad 42 holding the wafer 200 is transported (carried out) toward the spinner cleaning mechanism 39. During transport, the water film 210 keeps the circular recess 207 of the wafer 200 from drying out.

[0050] During this transfer, the space 209 in which the water film 210 is formed is at atmospheric pressure, so that the central portion of the wafer 200 during transfer can be prevented from sagging, which would cause strong stress on the wafer 200, and damage to the wafer 200 can be prevented.

[0051] Fig. 5 is a cross-sectional view similar to Fig. 4, showing a state in which the wafer is cleaned during transportation. As shown in Fig. 5, the grinding apparatus 1 can employ a configuration in which the pivoting movement of the arm 45 and the like is temporarily stopped during transportation toward the spinner cleaning mechanism 39, and the underside of the wafer 200 held by the suction pad 42 is cleaned by the cleaning unit 87. The cleaning unit 87 includes a rotary shaft 89 extending vertically, cleaning brushes 88 extending radially from the rotary shaft 89, and a motor (not shown) that rotates the rotary shaft 89. In this configuration, the cleaning unit 87 brings the cleaning brush 88, which rotates as the rotating shaft 89 rotates, into contact with the protective tape 205 on the back surface 202 of the wafer 200, and further moves the suction pad 42 horizontally to clean the protective tape 205.

[0052] During this cleaning, a horizontal force is applied to the wafer 200 from the cleaning brush 88. In this embodiment, the seal portion 83 of the suction pad 42 is brought into surface contact with the chamfered portion 206 of the wafer 200, and annular ribs 81 are provided on the outer sides of the seal portion 83 and the chamfered portion 206, thereby preventing the wafer 200 from sliding sideways relative to the suction surface 61 during cleaning. Even if a horizontal force is applied to the wafer 200 held by the suction pad 42 due to the pivotal movement of the arm 45, etc., the annular rib 81 can prevent the wafer 200 from sliding sideways.

[0053] After being cleaned by the cleaning unit 87, the wafer 200 is transported to the spinner cleaning mechanism 39 by driving the moving mechanism 43 while being held by the suction pad 42. Then, the water supply valve 72 and the suction valve 68 are controlled to close, the wafer 200 is released from the suction pad 42, and the wafer 200 is placed in the spinner cleaning mechanism 39, completing the transport.

[0054] As described above, according to the first embodiment, the annular rib 81 is provided so that the seal portion 83 comes into surface contact with the chamfered portion 206 of the wafer 200, thereby enabling the seal portion 83 to exhibit good sealing properties between the wafer 200 and the suction pad 42. This ensures sealing (liquid-tightness) between the inside and outside of the space 209 through the contact portion between the seal portion 83 and the chamfered portion 206 while the wafer 200 is held by the suction pad 42. As a result, the pressure in the space 209 with the water film 210 formed can be maintained, and the wafer 200 can be held by the suction pad 42 for stable transport.

[0055] Furthermore, since the insertion part 82 is inserted into the space 209 from above and the volume of the space 209 is reduced by the insertion part 82, the amount of water required to form the water film 210 can be reduced.

[0056] Next, other embodiments of the present invention will be described. In the following description, the same reference numerals may be used to designate components that are the same as or equivalent to those in the embodiments described before the embodiment, and the description thereof may be omitted or simplified.

[0057] [Second embodiment] A second embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 is a partially enlarged view of a carry-out mechanism in the second embodiment, similar to Fig. 4. As shown in Fig. 6, in the second embodiment, the diameter of the suction pad 42 is smaller than in the first embodiment, and the position of the seal portion 83 is different. In addition, in the second embodiment, the inner peripheral surface 212 of the circular recess 207 in the wafer 200 is not parallel to the thickness direction of the wafer 200 and is formed into a tapered surface whose diameter gradually increases in the direction from the back surface 202 to the front surface 201.

[0058] The suction pad 42 in the second embodiment does not have the annular rib 81 of the first embodiment, and includes a horizontal portion 90 formed to protrude laterally from the upper end of the insertion portion 82 and facing the annular protrusion 208 of the wafer 200. Furthermore, the insertion portion 82 in the second embodiment has a tapered outer peripheral surface that is parallel to the tapered inner peripheral surface 212 of the circular recess 207, and is inserted into the circular recess 207.

[0059] The seal portion 83 in the second embodiment is attached so as to follow the outer peripheral surface of the insertion portion 82 of the suction pad 42 and the horizontal portion 90, and is formed in a closed loop (ring shape) corresponding to the outer peripheral portion of the wafer 200. Therefore, the seal portion 83 is in surface contact with the upper end surface (tip surface) of the annular protrusion 208, which forms the outer peripheral portion of the wafer 200, and the inner peripheral surface 212 of the circular recess 207. Also in the second embodiment, when the suction pad 42 suction-holds the wafer 200, only the seal portion 83 comes into contact with the wafer 200.

[0060] With the wafer 200 held by suction on the suction pad 42, the insertion portion 82 is inserted into the inside of the circular recess 207 of the wafer 200. As a result, the annular protrusion 208 of the wafer 200 surrounds the insertion portion 82, and a seal portion 83 is interposed between the insertion portion 82 and the inner peripheral surface 212 of the circular recess 207. Therefore, the lateral movement of the wafer 200 held by suction on the suction pad 42 (directions parallel to the XY plane) is restricted by the insertion portion 82 and the seal portion 83. In other words, the insertion portion 82 functions as a lateral slip prevention portion that prevents lateral slip of the wafer 200 held by suction on the suction surface 61, and is disposed so that the seal portion 83 is in surface contact with the inner peripheral surface 212 of the circular recess 207 of the wafer 200.

[0061] As described above, according to the second embodiment, the insertion portion 82 is provided so that the seal portion 83 comes into surface contact with the inner peripheral surface 212 of the circular recess 207 of the wafer 200. This makes it possible to prevent the above-mentioned lateral slippage of the wafer 200, while allowing the seal portion 83 to exhibit good sealing performance between the wafer 200 and the insertion portion 82.

[0062] [Third embodiment] A third embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is a partially enlarged view of the carrying-out mechanism in the third embodiment, similar to FIG. 4. As shown in FIG. 7, in the third embodiment, the position of the seal portion 83 is changed compared to the second embodiment, and a lateral slip prevention portion 92 is provided on the horizontal portion 90 of the suction pad 42. Note that in the third embodiment, as in the first embodiment, the inner peripheral surface 212 of the circular recess 207 in the wafer 200 is parallel to the thickness direction of the wafer 200, and the outer peripheral surface of the insertion portion 82 is also parallel to the vertical direction when inserted into the circular recess 207.

[0063] The seal portion 83 in the third embodiment is attached to the horizontal portion 90 of the suction pad 42 and is formed in a closed loop (ring shape) corresponding to the outer periphery of the wafer 200. Therefore, the seal portion 83 is in surface contact with the upper end surface (tip surface) of the annular protrusion 208 that forms the outer periphery of the wafer 200. In the third embodiment as well, when the suction pad 42 suction-holds the wafer 200, only the seal portion 83 is in contact with the wafer 200.

[0064] 7 shows only one anti-skid portion 92, but it is actually provided at multiple locations spaced apart around the circumferential direction of the suction pad 42; for example, it is provided at three locations at 120° intervals around the center of the circular suction pad 42. The anti-skid portion 92 includes a support protrusion 93 that protrudes downward from the horizontal portion 90, and a buffer member 94 attached to the support protrusion 93. The buffer member 94 of each anti-skid portion 92 is provided so as to be in contact with the inner circumferential surface 212 of the circular recess 207 while exerting elasticity, and is formed, for example, from a sponge similar to the seal portion 83.

[0065] When the wafer 200 is held by suction on the suction pad 42 and the insertion portion 82 is inserted inside the circular recess 207 of the wafer 200, the buffer members 94 of the anti-side slippage portion 92 come into contact with the inner peripheral surface 212 of the circular recess 207. The buffer members 94 are sandwiched laterally between the support protrusion 93 and the inner peripheral surface 212 of the circular recess 207, and since the anti-side slippage portions 92 are provided at multiple locations, the lateral movement (direction parallel to the XY plane) of the wafer 200 held by suction on the suction pad 42 is restricted. As a result, the multiple anti-side slippage portions 92 can prevent the wafer 200 held by suction on the suction surface 61 from sliding sideways.

[0066] As described above, according to the third embodiment, the plurality of anti-slip portions 92 can prevent the wafer 200 held by suction from sliding sideways, and the sealing portion 83 that comes into surface contact with the annular protrusion 208 of the wafer 200 can exhibit good sealing properties.

[0067] [Fourth embodiment] A fourth embodiment of the present invention will be described with reference to Fig. 8. Fig. 8 is a partially enlarged view of the discharge mechanism in the fourth embodiment, similar to Fig. 4. As shown in Fig. 8, in the fourth embodiment, the installation position of the anti-skid unit 92 is changed from that in the third embodiment.

[0068] 8 shows only one anti-slip portion 96 of the fourth embodiment, but it is provided at multiple locations spaced apart around the circumferential direction of the suction pad 42, for example, at three locations spaced at 120° intervals around the center of the circular suction pad 42. The anti-slip portion 96 includes a support protrusion 97 that protrudes outward from the outer circumferential surface of the suction pad 42, and a buffer member 98 attached to the underside of the support protrusion 97. The buffer member 98 of each anti-slip portion 96 is provided so as to be able to come into contact with the chamfered portion 206 of the wafer 200 while exerting elasticity, and is formed, for example, from a sponge similar to the seal portion 83.

[0069] With the wafer 200 held by suction on the suction pad 42, the buffer members 98 of the anti-side slippage parts 96 come into contact with the chamfered portion 206 of the wafer 200. The buffer members 98 are arranged to cover the chamfered portion 206 from diagonally above, restricting movement of the wafer 200 to the right in FIG. 8 . The multiple anti-side slippage parts 96 bring the buffer members 98 into contact with multiple points on the chamfered portion 206, restricting movement of the wafer 200 held by suction on the suction pad 42 in the lateral direction (direction parallel to the XY plane). As a result, the multiple anti-side slippage parts 96 can prevent the wafer 200 held by suction on the suction surface 61 from sliding sideways.

[0070] As described above, according to the fourth embodiment, the plurality of anti-slip portions 96 can prevent the wafer 200 held by suction from sliding sideways, and the sealing portion 83 that comes into surface contact with the annular protrusion 208 of the wafer 200 can exhibit good sealing properties.

[0071] The present invention is not limited to the above-described embodiments, and various modifications can be made to the present invention. In the above-described embodiments, the size and shape shown in the accompanying drawings are not limited to these, and can be modified as appropriate within the scope of the effects of the present invention. In addition, the present invention can be modified as appropriate without departing from the scope of the object of the present invention.

[0072] For example, in each of the first, third and fourth embodiments, the inner circumferential surface of the circular recess 207 in the wafer 200 and the outer circumferential surface of the insertion portion 82 may be formed in a tapered shape as in the second embodiment.

[0073] Furthermore, in each of the first, third, and fourth embodiments, the suction surface 61 may be formed in a flat shape at the height of the horizontal portion 90 without forming the insertion portion 82 of the suction pad 42. However, forming the insertion portion 82 is advantageous in that it reduces the volume of the space 209 and the amount of water required to form the water film 210.

[0074] Furthermore, the water film supply section and pressure adjustment section of the suction pad 42 are configured using the tubular member 63, but in addition to the tubular member 63, a pump or a valve connected to the tubular member 63 via a flow path may be provided on the suction pad 42 to be included in the water film supply section or pressure adjustment section.

[0075] Furthermore, in each of the above embodiments, the unloading mechanism 38 serving as a work transport device is applied to the grinding device 1, but this is not limited to this, and it may also be applied to other processing devices, such as a polishing device that polishes the wafer 200. [Industrial Applicability]

[0076] As described above, the present invention has the effect of stably holding a wafer having a chamfered outer edge by suction with a suction pad via a water film, while preventing the wafer from sliding sideways with the sliding prevention part, and also exhibiting good sealing between the suction pad and the wafer with the sealing part. [Explanation of symbols]

[0077] 38: Unloading mechanism (wafer transport device) 42: Suction pad 43: Movement mechanism 61: Suction surface 63: Tubular member (water membrane supply section, pressure adjustment section) 81: Annular rib (anti-skid part) 82: Insertion part (anti-skid part) 83: Seal part 92: Anti-skid section 96: Anti-skid section 200: wafer 201: Surface (top surface) 202: Back side (bottom side) 206: Chamfered part 207: Circular recess 208: Annular convex part 209: Space 210: Water film 212: Inner surface

Claims

1. A wafer transport device for transporting a wafer, the wafer comprising: a suction pad that suction-holds, by a suction surface, an upper surface of a wafer having a circular recess in the center, an annular protrusion outside the circular recess, and a chamfered outer periphery; and a moving mechanism that moves the suction pad, The suction pad comprises a seal portion that contacts the outer peripheral portion of the wafer and forms a cylindrical space between the suction surface and the upper surface of the wafer, a water film supply portion that supplies water to the cylindrical space and forms a water film on the upper surface of the wafer, a pressure adjustment portion that adjusts the pressure of the space with the water film formed to atmospheric pressure, and a sideslip prevention portion that prevents sideslip of the wafer held by suction on the suction surface, the seal portion is formed in a closed loop shape according to the outer periphery of the wafer; The anti-skid portion is disposed so that the seal portion is in surface contact with the chamfered portion or the inner peripheral surface of the circular recess.

2. A wafer transport device for transporting a wafer, the wafer comprising: a suction pad that suction-holds, by a suction surface, an upper surface of a wafer having a circular recess in the center, an annular protrusion outside the circular recess, and a chamfered outer periphery; and a moving mechanism that moves the suction pad, The suction pad comprises a seal portion that contacts the outer peripheral portion of the wafer and forms a cylindrical space between the suction surface and the upper surface of the wafer, a water film supply portion that supplies water to the cylindrical space and forms a water film on the upper surface of the wafer, a pressure adjustment portion that adjusts the pressure of the space with the water film formed to atmospheric pressure, and a sideslip prevention portion that prevents sideslip of the wafer held by suction on the suction surface, The sealing portion is formed in a closed loop shape according to the outer periphery of the wafer and is in surface contact with the tip surface of the annular convex portion.

3. 3. The wafer transport device according to claim 1, wherein the suction pad has an insertion portion that is inserted into the inside of the circular recess of the wafer held by the suction surface.

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