Release device

Abstract

Release device (1) for releasing a protective element (S) from a wafer (W), wherein the protective element (S) comprises a resin (S1) and a film (S2) which is fixed to a surface of the wafer (W) with the resin (S1) in between, wherein the film (S2) has a protruding edge (S2a) which extends radially outwards beyond an outer circumferential edge (Wb) of the wafer (W), comprising: a holding means (2) having a holding surface (210a) for holding another surface of the wafer (W) thereon, wherein the wafer (W) with the protective element (S) is arranged below the holding means (2) such that the surface of the wafer (W) having the protective element (S) is directed downwards; a gripping means (3) for gripping the protruding edge (S2a) of the protective element (S) on the wafer (W) which is held by the holding means (2); a release agent (4) for releasing the protective element (S) from the wafer (W) by relative movement of the gripping agent (3) and the holding agent (2) radially inwards from the outer circumferential edge (Wb) of the wafer (W) to the center of the wafer (W); an image acquisition means (80) for taking an image of the surface of the wafer (W) on which the protective element (S) was formed, after the protective element (S) had been removed from the wafer (W) by the removal agent (4); and a decision-making device (19) for determining, using the image taken by the image-taking device (80), whether or not there are any remnants of the resin (S1) left on the wafer (W).

Description

BACKGROUND OF THE INVENTION Technical field

[0001] The present invention relates to a removal device for removing a protective element from a wafer. Description of the state of the art

[0002] To produce wafers with flat surfaces, it is common practice in the semiconductor wafer manufacturing process to start with a cylindrical ingot made of a raw material such as silicon and slice it into thin, disc-shaped wafers using a saw or similar tool. Since irregularities often exist on both surfaces of such a disc-shaped wafer, the wafer cut from the ingot is then planed flat. This involves holding rotating grinding wheels against the surface of the wafer that has been processed by the band saw to remove these irregularities, thus creating the planar surface.

[0003] The grinding process is described in detail below. As in Fig. As shown in Figure 6 of the accompanying figures, a protective element made of a liquid resin S1 is formed on a surface Wa of a disk-shaped wafer W. Specifically, a disk-shaped film S2, which is larger in diameter than the wafer W, is placed on a flat holder surface 90a of a holding table 90 of a release device for a protective element. Subsequently, a predetermined quantity of liquid resin S1 is supplied from a resin supply source 91 onto the film S2. The resin S1 can be cured by light, typically ultraviolet radiation.While the other surface Wb of wafer W is held under suction by the holding agent 92, wafer W is pressed downwards against the liquid resin S1 on the film S2, which is arranged in a position opposite surface Wa of wafer W. This causes the liquid resin S1 to be distributed over surface Wa of wafer W, thus covering the entire surface Wa with the liquid resin S1. The liquid resin S1 is then cured by ultraviolet radiation emitted by an ultraviolet radiation application agent 93, which is arranged, for example, in the holding table 90. This cures the liquid resin S by forming a protective element S on surface Wa of wafer W, as shown in [reference]. Fig. 7 of the accompanying figures are shown, and the film S2 includes a protruding edge S2a that extends radially outward behind an outer circumferential edge Wb of the wafer W.

[0004] As in Fig. As shown in Figure 7, the wafer W is placed on the holder surface of a clamping table 940 of a grinding device 94, such that the surface Wb of the wafer W, which does not have the protective element S2, faces upwards. A grinding wheel 941, which is rotated about its own axis, is then lowered from above the wafer W, thereby bringing the grinding stones 941a onto the surface Wb of the wafer W to grind the surface Wb of the wafer W to obtain a flat surface. The protective element S is then removed from the surface Wa of the wafer W by a removal device (see, for example, Japanese patent application JP 2013-168488A for details). The surface Wa of the wafer W, which is protected by the protective element S, is then ground flat. The wafer W now has two planar surfaces.

[0005] US 2014 / 0332166A1 discloses a separation device that separates a bonded substrate, in which a target substrate and a support substrate are bonded together by an adhesion promoter, into the target substrate and the support substrate. PRESENTATION OF THE INVENTION

[0006] To detach the protective element S from the wafer W, the surface Wb of the wafer W, which was ground first, is held under suction by a holding device, and the wafer W is lifted. The film S2 is then gripped by a gripping device, such as a clamp, and the gripping device is moved to detach the protective element S from the wafer W. At this point, however, residues of the plastic or resin S1 from the protective element S may remain on the surface Wa of the wafer from which the protective element S was detached. Such residues of resin S1 can be caused by air bubbles contained in the liquid resin S1 or by a defect in which the liquid resin S1 is not completely cured by the applied ultraviolet radiation at the time it forms the protective element S.

[0007] An objective of the present invention is to provide a removal device that is able to confirm, at the time when the protective element has been removed from the wafer, whether or not any residues of resin from a protective element remain on the wafer.

[0008] In accordance with one aspect of the present invention, a release device for removing a protective element from a wafer is provided, wherein the protective element comprises a resin and a film fixed to a surface of the wafer, the resin being inserted between them, the film having a protruding edge extending radially outward beyond an outer circumferential edge of the wafer, a holding means having a holding surface for holding another surface of the wafer thereon with the protective element arranged below the holding means such that the surface of the wafer having the protective element faces downward, and a gripping means for gripping the protruding edge of the protective element on the wafer held by the holding means.a release agent for removing the protective element from the wafer by moving the gripping and holding means radially inwards from the outer circumferential edge of the wafer to a center of the wafer, an image acquisition means for capturing an image of the surface of the wafer on which the,

[0009] The protective element was formed after the protective element was removed from the wafer by the removal agent, and includes a decision means to determine whether or not residues of the resin remain on the wafer from the image acquired by the image acquisition device.

[0010] After the release agent has detached the protective element from the wafer by moving the gripping and holding means radially inwards from the outer circumferential edge of the wafer to the center of the wafer, the image acquisition means takes an image of the one surface of the wafer on which the protective element was formed, and the decision means determines with the image taken by the image acquisition means whether or not any resin residues remain on the wafer.

[0011] The above and other aims, features and advantages of the present invention and the manner of realizing them will become clearer and the invention itself will best be understood by studying the following description and an attached claim with reference to the attached figures, which show a preferred embodiment of the invention. BRIEF DESCRIPTION OF THE FIGURES Fig. Figure 1 is a perspective view of a release device according to an embodiment of the present invention; Fig. 2 is a cross-sectional view showing the way in which a protruding edge of a protective element on a wafer held by a holding means is grasped by circular means; Fig. Figure 3 is a cross-sectional view showing the way in which the gripping means that grips the protruding edge of the protective element is moved by the release means and the holding means is moved in a direction opposite to the release means, a beginning of the release of the protective element from the wafer; Fig. Figure 4 is a cross-sectional view showing the way in which the gripping means that grips the protruding edge of the protective element is moved by the release means and the holding means is moved in the direction opposite to the release means, whereby the main part of the protective element is detached from the wafer; Fig. Figure 5 is a cross-sectional view showing the way in which the surface of the wafer on which the protective element has been formed is captured by the image acquisition device; Fig. Figure 6 is a side view, partially schematically showing in cross-section the way in which a protective element made of a liquid resin is formed on the surface of a wafer; and Fig. Figure 7 is a side view showing the way in which the protective element is held and the other surface of the wafer is ground. DETAILED DESCRIPTION OF THE PREFERRED VERSION

[0012] A release device 1, which is in Fig. Figure 1 shows a device for detaching a protective element S from a wafer W. The protective element S has a larger diameter than the wafer W and is attached to a surface Wa of the wafer W, as shown in Figure 1. Fig. The protective element S, shown in Figure 2, has a projecting edge S2a that extends radially outward behind an outer circumferential edge Wd of the wafer W. The release device 1 comprises a base 10 and an upwardly projecting column 11, which is mounted on a rear section in a -X direction of the base 10. On an upper section of a side surface in a +X direction of the column 11, a Y-direction motion means 12 is arranged for moving a holding means 2 back and forth in Y directions on a movable plate 121 by rotating a ball screw 120 about its own axis with a motor 122.

[0013] A Z-direction motion device 13 for moving the holding element 2 back and forth in the Z directions is arranged on the movable plate 121. The Z-direction motion device 13 moves the holding element 2 back and forth in the Z directions by rotating a ball screw 130 about its own axis with a motor 132.

[0014] The holding device 2 includes an arm 20, one end of which is fixed in the -X direction to the movable plate 131, and a holding pad 21 for holding the wafer W under suction, the holding pad 21 being located on the lower surface of another end in the +X direction of the arm 20. As shown in Fig. As shown in Figure 2, the retaining pad 21 includes a suction attractor 210, made of a porous material for attracting the wafer W under suction, and a frame 211 that supports the suction attractor 210. The suction attractor 210 is fluidly connected to a suction source 213 by means of a suction tube 212. When the suction source 213 is actuated, suction forces are generated by drawing in air, and these suction forces are transmitted through the suction tube 212 to a retaining surface 210a, which is provided as an exposed surface of the suction attractor 210 and is flush with a lower surface of the frame 211. This allows the retaining means 2 to hold the wafer W under suction against the retaining surface 210a.

[0015] At an intermediate area of ​​the side surface in the +X direction of column 11, which is in Fig. As shown in Figure 1, i.e., below the path along which the holding means 2 can be moved, a rotary roller 18, having a central axis extending in the X directions, a release means 4 for releasing the protective element S from the wafer W, a movement means 81 for an image acquisition means for moving an image acquisition means 80 that captures the surface Wa of the wafer W, a placement table 5 for placing the protective element S on it after it has been released from the wafer W, and a release means 6 for releasing the protective element S from the placement table 5 are successively inserted. Near the release means 4 in the +Y direction, a table holding projection 140 is fixed to the side surface of the column 11 in the +X direction. The table holding projection 140 carries a transfer table 141 on it, in order to place the wafer W on it after it has been ground.The transfer table 141 holds the wafer W under suction on its holder surface 141a.

[0016] The release device 4 comprises a ball screw 40 having a central axis extending in the Y directions, a pair of guide rails 41 arranged parallel to the ball screw 40, a motor 42 for rotating the ball screw 40 about its own axis, and a movable block 43 having an internal thread that receives the ball screw 40 and a pair of lateral sections that are held in sliding contact with the guide rails 41. When the motor 42 is actuated to move the ball screw 40 about its own axis, the movable block 43 is moved in one of the X directions while being guided by the guide rails 41, causing the gripping device 3, which is arranged on the movable block 43, to move in the same direction.

[0017] The gripping device 3 comprises a spindle 30 having a central axis extending in the X directions, a housing 31 rotatably supporting the spindle 30, and a gripping clamp 32 located at the distal end of the spindle 30 in the +X direction. The gripping clamp 32 includes a pair of hinged gripper plates 320 that can be moved away from and towards each other to grip a workpiece between them. When the spindle 30 rotates about its own axis, the angle at which the gripping clamp 32 grips the workpiece changes. The gripping device 3 can be vertically movable on the movable block 43.

[0018] The rotating roller 18 has an outer cylindrical shape and is rotatable about its axis in the X direction by a motor (not shown). The rotating roller 18 rests against the protective element S to prevent the resin S1, which is contained in Fig. Figure 2 shows how the protective element S is detached from the wafer W. The rotating roller 18 can be moved in the Y direction.

[0019] The motion device 81 for an image acquisition device comprises a ball screw 810 having a central axis extending in the Y directions, guide rails 41 arranged parallel to the ball screw 810, a motor 812 for rotating the ball screw 810 about its own axis, and a movable block 813 having an internal thread in which the ball screw 310 is received and a pair of side sections that are held in sliding contact with the guide rails 41. When the motor 812 is actuated to rotate the ball screw 810 about its own axis, the movable block 813 moves in one of the Y directions while being guided by the guide rails 41, causing the imaging device 80, which is arranged on the movable block 813, to move in the same direction.

[0020] The imaging means 80, which is arranged on the movable block 813, includes, for example, a line sensor in the form of a charge-coupled device (CCD) sensor or the like. The image acquisition means 80 has a length in the X directions that is equal to or greater than the diameter of the holding pad 21 of the holding means 2, such that the imaging means 80 has a measurement field longer than the diameter of the wafer W. The imaging means 80 has an image acquisition unit 800, which includes an array of image detectors arranged along the X directions, and is arranged on the movable block 813 such that the image acquisition unit 800 faces upwards. The image acquisition means 80 can capture the surface Wa of the wafer W, which is held by the holding means 2 and positioned above the acquisition means 80. The decision means 19 includes a central processing unit (CPU), a memory element, etc.It includes, is electrically connected to the image acquisition device 80.

[0021] The placement table 5 is essentially rectangular and has, for example, a rib-like placement surface 5a. In particular, the placement table 5 includes several parallel straight slats 50 extending along the Y-directions and spaced equally apart in the X-directions. The slats 50 are securely connected at their ends in the +Y-direction by a rod-like connector (not shown). The placement table 5 is fixed to the side surface in the +X-direction of the column 11 by the rod-like connector that joins the slats 50. Alternatively, the placement table 5 has a lower surface 5b that is partially fixed to side surfaces 61c of the pair of guide rails 61 of the discharge device 6, which will be described later. Consequently, the placement table 5 is positioned below the path along which the gripping device 3 and the holding device 2 can be moved.

[0022] The ejection means 6 includes a ball screw 60 having a central axis extending in the X directions, a pair of guide rails 61 arranged parallel to the ball screw 60, a motor 62 for rotating the ball screw 60 about its own axis, a movable block 63 having an internal thread engaging with the ball screw 60 and a side section 630 held in sliding contact with the guide rails 61, and a pair of ejector pins 64 arranged on the movable block 63.

[0023] The movable block 63 has a side section 630 that engages with the ball screw 60 and a pin carrier 631 that projects from an upper end of the side section 630 in the +X direction. The two ejector pins 64, projecting in the +Z direction, are arranged on an upper surface of the pin carrier 631. The ejector pins 64 are spaced apart from each other at a predetermined distance in the X directions. When the motor 62 is actuated to rotate the ball screw 60 about its own axis, the movable block 63 moves in one of the Y directions as it is guided by the guide rails 61, causing the ejector pins 64, which are arranged on the movable block 63, to move in the same direction through the gap between the slats 50 of the placement table 5.

[0024] A box 7 for receiving the protective element S, which has been detached from the wafer W, is mounted on the base 10. The box 7 has an outer shape, for example, essentially a rectangular parallelepiped, open at the top below one end in the +Y direction of the placement table 5. At its upper end, the box 7 carries a transparent optical sensor 79, which includes a light emitter 790 offset in the -Y direction and a light detector 791 offset in the +Y direction. Protective elements S, which are successively detached from wafers W, are placed individually on the placement table 5 and then ejected from the placement table 5 into the box 7 by the ejection device 6.When the protective elements S are stacked in the box 7 up to a certain height, the uppermost protective element S interrupts an inspection light beam emitted by the light emitter 790 to the light detector 791, causing the optical sensor 79 to detect that the box 7 has been filled with protective elements S.

[0025] The actuation of the release device 1 for detaching the protective element S from the wafer is described below with reference to Fig. 1-5 described. Fig. Figure 2-5 shows a simplified representation of the release device 1.

[0026] As in Fig. As shown in Figure 1, the ground wafer W is placed on the transfer table 141 with the ground surface Wb facing upwards. The holding device 2 moves in the +Y direction to a position above the wafer W until the center of the holding surface 210a of the holding pad 21 is substantially aligned with the center of the surface Wb of the wafer W. The holding device 2 is lowered in the -Z direction until the holding surface 210a of the holding pad 21 is brought into contact with the surface Wb of the wafer W. The suction source 213 is actuated so that it generates suction forces which are transmitted to the holding surface 210a, causing the holding device 2 to hold the surface Wb of the wafer W under suction, with the protective element S positioned below it.

[0027] As in Fig. As shown in Figure 2, the holding element 2, which holds the wafer W under suction, moves in the -Y direction to a position above the rotating roller 18 and lowers to bring the side surface 18c of the rotating roller 18 into contact with a lower surface Sb of the protective element S near an outer circumferential section thereof in the +Y direction. The release element 4 moves the gripping element 3 in the -Y direction to align the gripping clamp 32 and the protruding edge S2a of the protective element S with each other. The gripping clamp 32 then grips the protruding edge S2a of the protective element S. The protective element S comprises a resin S1 and a film S2, the film S2 being attached to the surface Wa of the wafer W with the resin S1 inserted between them.

[0028] As in Fig. As shown in Figure 3, after the gripping clamp 32 firmly grasps the protruding edge S2a of the protective element S, the spindle 30 rotates clockwise through 90° about its own axis, viewed in the plus X direction. While the rotating roller 18 carries the lower surface Sb of the protective element S, the resin S1 of the protective element S is gradually bent along the side surface 18c of the rotating roller 18, and the protective element S is pulled in the -Z direction by the gripping clamp 32, so that a portion of the protective element S is detached from the surface Wa of the wafer W.

[0029] Subsequently, the release agent 4 moves the gripping agent 3 and the holding agent 2 relatively radially inward from the outer circumferential edge Wb of the wafer W to its center, thereby detaching the protective element S from the wafer W. Specifically, the release agent 4 moves the gripping agent 3 in the -Y direction, and the movement agent 12 for the Y direction moves, for example, the holding agent 2 in the +Y direction. The rotary roller 18 rotates about its own axis along the X directions, and while the resin S1 of the protective element S is gradually bent along the side surface 18c of the rotary roller 18, the protective element S is detached from the wafer W in the -Y direction from the outer circumferential edge Wd in the +Y direction of the wafer W.If the resin S1 folds when the protective element S is removed, residues of the resin S1 may remain on the wafer W, and the surface Wa of the wafer W may be damaged by forces exerted on the surface Wa of the wafer W directly as a reaction to the behavior of the resin S1. However, since the side surface 18c of the rotating roller 18 is held in contact with the film S2, the occurrence of such problems on the wafer W is prevented.

[0030] As in Fig. As shown in Figure 4, when the gripping means 30 is moved to a position near the outer circumferential edge Wd in the -X direction of the wafer W, the spindle 30 rotates further clockwise by 90° about its own axis, viewed in the +X direction, thereby directing the resin S1 of the protective element S2 downwards. The moving means 12 for a Y direction moves the holding means 2 in the +Y direction, and the releasing means 4 moves the gripping means 3 in the -Y direction, thereby completely detaching the protective element S from the wafer W. When the protective element S has been completely detached from the wafer, the gripping clamp 32 opens to release the protruding edge S2a of the protective element S from the gripping means 3, thereby dropping the protective element S onto the placement table 5 with the resin S1 facing downwards.

[0031] Then the release agent 4 stops the movement of the gripping agent 3, and the movement agent 12 for an X direction stops the movement of the holding agent 2. As in Fig. As shown in Figure 5, the motion means 81 for an image acquisition means moves the image acquisition means 80 in the -Y direction, causing the imaging means 80 to move below the wafer W, which is held by the holding means 2. During a movement of the imaging means 80 below the wafer W, the image acquisition unit 800 of the imaging means 80 continuously acquires images of the surface Wa of the wafer W from the outer circumferential edge Wd in the +Y direction of the wafer W to the outer circumferential edge Wd in the -Y direction of the wafer W, thereby acquiring an image of the entire surface Wa of the wafer W.

[0032] The image acquisition device 80 sends the data of the captured image to the decision device 19, which is located in Fig.1 is shown. If the resin S1 is represented as pixels that have inherent color information in the recorded image, the decision instrument 19 decides that residues of the resin S1 of the protective element S remain on the surface Wa of the wafer W from which the protective element S was detached.

[0033] The release device 1 according to the present invention essentially operates as follows: The release agent moves the gripping agent 3 and the holding agent 2 radially inward relative to each other from the outer circumferential edge Wb of the wafer W to its center, thereby releasing the protective element S from the wafer W. Subsequently, the imaging agent 80 acquires an image of the surface Wa of the wafer in which the protective element S is formed, and the decision agent 19 uses the acquired image to determine whether or not residues of the resin S1 remain on the surface Wa of the wafer W.

[0034] If the decision device 19 determines that residues of resin S1 remain on the surface a of wafer W from which the protective element S was detached, then wafer W with the residues of resin S1 is not stored in a wafer cassette, but is separated from the other normal wafers W. The operator can then remove the residues of resin S1 from the surface WA of wafer W or send wafer W with the residues of resin S1 back to the protective element training device or the like, where a protective element is repeatedly formed on the surface Wa of wafer W. The newly formed protective element S is then detached from wafer W again by the removal device 1, thereby removing the residues of resin S1 from wafer W.Consequently, only the wafers on which no residues of the resin S1 are present are fed to a grinding device and ground by it, so that wafers which have irregularities in their thickness and are therefore not flat are not produced.

[0035] The release device 1 is not limited to the embodiment described above, and the sizes, shapes, and other details of the release device 1 shown in the accompanying figures are not limited to these embodiments but can be changed or modified within the scope of the invention. For example, the release means 4, the holding means 2, and the gripping means 3 can move radially inward from the outer circumferential edge Wb of the wafer W to a center thereon, so that the protective element S is released from the wafer W. In this case, the gripping means 3 does not move in the Y directions, but the holding means 2 does move in the Y directions to release the protective element S from the wafer W. The image acquisition means 80 need not move in the Y direction; only the holding means 2 can move in the Y directions to allow the image acquisition means 80 to capture the surface Wa of the wafer W from which the protective element S has been released.The image acquisition device 80 is not limited to a line sensor, but can be an area sensor or the like.

Claims

[1] Release device (1) for releasing a protective element (S) from a wafer (W), wherein the protective element (S) comprises a resin (S1) and a film (S2) which is fixed to a surface of the wafer (W) with the resin (S1) in between, wherein the film (S2) has a protruding edge (S2a) which extends radially outwards beyond an outer circumferential edge (Wb) of the wafer (W), comprising: a holding means (2) having a holding surface (210a) for holding another surface of the wafer (W) thereon, wherein the wafer (W) with the protective element (S) is arranged below the holding means (2) such that the surface of the wafer (W) having the protective element (S) is directed downwards; a gripping means (3) for gripping the protruding edge (S2a) of the protective element (S) on the wafer (W) which is held by the holding means (2); a release agent (4) for releasing the protective element (S) from the wafer (W) by relative movement of the gripping agent (3) and the holding agent (2) radially inwards from the outer circumferential edge (Wb) of the wafer (W) to the center of the wafer (W); an image acquisition means (80) for taking an image of the surface of the wafer (W) on which the protective element (S) was formed, after the protective element (S) had been removed from the wafer (W) by the removal agent (4); and a decision-making device (19) for determining, using the image acquired by the image-acquiring device (80), whether or not there are any remnants of the resin (S1) remaining on the wafer (W).

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