Removal method

Abstract

To detect whether or not a ring-shaped reinforcement part which partially cracks and remains on an adhesive tape exists.SOLUTION: A ring-shaped reinforcement part is removed from a wafer including a circular thin plate part and the ring-shaped reinforcement part. A removal method includes: a step in which three or more scraper members are inserted into a space between the ring-shaped reinforcement part and an adhesive tape and moved along an outer periphery of the wafer and then the ring-shaped reinforcement part is moved upward so as to move apart from a chuck table to remove the ring-shaped reinforcement part from the adhesive tape; a step in which a sensor unit provided at an outer periphery part on the lower surface side of a discoid support member supporting the three or more scraper members to detect whether or not the ring-shaped reinforcement part is held by the three or more scraper members; a step in which the ring-shaped reinforcement part is transported to a collection box; and a step in which the sensor unit is positioned at an outer peripheral part of the wafer from which the ring-shaped reinforcement part is removed to detect whether or not a partial remaining part of the ring-shaped reinforcement part exists.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a removal method for removing a ring-shaped reinforcing portion located on the outer peripheral portion of a wafer from the wafer constituting a wafer unit.

Background Art

[0002] In recent years, thinning of device chips has been required for weight reduction and miniaturization of electronic devices. To meet this requirement, the entire back side of a wafer having a plurality of devices formed on the front side is ground to thin the wafer thickness.

[0003] However, a wafer thinned by grinding the entire back side has reduced rigidity and warpage compared to before grinding, which may make it difficult to handle the wafer. For example, in a conveyance process after the thinning process, there is a risk that the wafer may be damaged.

[0004] Therefore, a grinding method has been proposed in which, without grinding the outer peripheral portion of the wafer, a circular region on the back side of the wafer corresponding in the thickness direction to a device region located at the central portion in the radial direction of the wafer surface and having a plurality of devices formed thereon is ground, leaving a ring-shaped reinforcing portion on the outer peripheral portion of the wafer.

[0005] By leaving the ring-shaped reinforcing portion, it becomes easier to handle the wafer compared to a wafer thinned by grinding the entire back side. However, before dividing the thinned wafer into a plurality of device chips, it is necessary to remove the ring-shaped reinforcing portion.

[0006] Specifically, first, the central portion of an adhesive tape is attached to the back side of a wafer on which a ring-shaped reinforcing portion is formed, and the outer peripheral portion of the adhesive tape is attached to one surface of an annular frame having a circular opening with a diameter larger than that of the wafer.

[0007] Next, the boundary region between the circular thin plate portion containing the device area and the ring-shaped reinforcing portion surrounding the circular thin plate portion in the circumferential direction of the wafer is cut, separating the wafer into the circular thin plate portion and the ring-shaped reinforcing portion. After that, the ring-shaped reinforcing portion is peeled off and removed from the adhesive tape using a scraper member (see, for example, Patent Document 1).

[0008] However, if a portion of the ring-shaped reinforcement is missing and remains on the adhesive tape, this residue will interfere with the subsequent cutting process when dividing the circular thin plate into device units. Furthermore, this residue can contaminate equipment used in subsequent processes such as the cutting process. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2014-170822 [Overview of the project] [Problems that the invention aims to solve]

[0010] This invention has been made in view of the aforementioned problems, and aims to detect the presence or absence of a ring-shaped reinforcing portion that has been partially chipped off and remains on the adhesive tape when removing the ring-shaped reinforcing portion from the adhesive tape using a scraper member. [Means for solving the problem]

[0011] According to one aspect of the present invention, a removal method for removing a ring-shaped reinforcing portion located on the outer periphery of a wafer constituting a wafer unit, wherein the wafer unit includes a circular thin plate portion defining one surface of a circular recess formed on its back side, and a ring-shaped reinforcing portion defining the side surface of the circular recess and being thicker than the circular thin plate portion, and the wafer has an annular groove formed to separate the circular thin plate portion and the ring-shaped reinforcing portion; an adhesive tape with its central portion attached to the back side of the wafer; and an annular frame with the outer periphery of the adhesive tape attached to one surface of the annular frame, wherein the wafer unit is held by suction using a chuck table having a holding surface with a diameter smaller than the diameter of the circular recess; and three or more disc-shaped scraper members arranged apart from each other in the circumferential direction of a predetermined circle, between the ring-shaped reinforcing portion and the adhesive tape. A removal method is provided, comprising: a ring-shaped reinforcement removal step of removing the ring-shaped reinforcement from the adhesive tape by inserting it and moving it along the outer circumference of the wafer, and then moving the ring-shaped reinforcement upward so as to move it away from the chuck table; a first detection step of detecting whether the ring-shaped reinforcement is held by the three or more scraper members using a sensor unit that includes one or more optical sensors provided on the outer circumference of the lower side of a disc-shaped support member that supports the three or more scraper members, after the ring-shaped reinforcement removal step; a transport step of transporting the ring-shaped reinforcement held by the three or more scraper members to a collection box after the first detection step; and a second detection step of positioning the sensor unit on the outer circumference of the wafer from which the ring-shaped reinforcement has been removed, and detecting whether there is any partial remaining ring-shaped reinforcement after the transport step.

[0012] Preferably, in the second detection step, the sensor unit is moved along the outer circumference of the wafer by rotating the support member around a predetermined axis of rotation, and the presence or absence of any remaining portion of the ring-shaped reinforcing portion is detected around the entire circumference of the wafer. [Effects of the Invention]

[0013] In a removal method according to one aspect of the present invention, after removing the ring-shaped reinforcing portion from the adhesive tape, a sensor unit provided on the outer circumference of the lower side of a disc-shaped support member that supports three or more scraper members is used to detect whether or not the ring-shaped reinforcing portion is being held by the three or more scraper members (first detection step).

[0014] Furthermore, after the first detection step, the ring-shaped reinforcement is transported to a recovery box (transportation step), and after the transport step, the sensor unit is positioned again on the outer circumference of the wafer from which the ring-shaped reinforcement has been removed, and the sensor unit detects whether or not there is any partial remaining ring-shaped reinforcement (second detection step).

[0015] In this way, by utilizing multiple sensor units, it is possible to detect not only whether the ring-shaped reinforcement is held by three or more scraper members, but also whether there are any remaining parts of the ring-shaped reinforcement. Therefore, if there are any remaining parts of the ring-shaped reinforcement, they can be removed from the adhesive tape so as not to interfere with subsequent cutting or other processing steps. [Brief explanation of the drawing]

[0016] [Figure 1] This is a flowchart of the removal method. [Figure 2] Figure 2(A) is a perspective view of the front side of the wafer, Figure 2(B) is a perspective view of the back side of the wafer, and Figure 2(C) is a cross-sectional view of the wafer. [Figure 3] This is a diagram showing the holding process. [Figure 4] This is a top view of the removal and transport unit, etc. [Figure 5] Figure 5(A) is a partial cross-sectional side view showing the insertion of the lower scraper member, and Figure 5(B) is a perspective view showing the movement of the scraper unit. [Figure 6] Figure 6(A) is a partial cross-sectional side view showing the movement of the ring-shaped reinforcement, and Figure 6(B) is a perspective view showing the movement of the ring-shaped reinforcement. [Figure 7] This is a partial cross-sectional side view showing the first detection process. [Figure 8] It is a partial cross-sectional side view showing a conveying process. [Figure 9] It is a partial cross-sectional side view showing a second detection process. [Figure 10] FIG. 10(A) is a top view showing an example of a defect in the ring-shaped reinforcing portion, and FIG. 10(B) is a top view showing another example of a defect in the ring-shaped reinforcing portion.

Embodiments for Carrying Out the Invention

[0017] Referring to the accompanying drawings, embodiments according to an aspect of the present invention will be described. FIG. 1 is a flowchart of a removing method for removing a ring-shaped reinforcing portion 27 (see FIGS. 2(B) and 2(C)) located on the outer peripheral portion of a wafer 11 from the wafer 11.

[0018] As shown in FIG. 1, in the present embodiment, each process is performed in the order of a holding process S10, a ring-shaped reinforcing portion removing process S20, a first detection process S30, a conveying process S40, and a second detection process S50. Therefore, first, the wafer 11 to be processed will be described.

[0019] FIG. 2(A) is a perspective view of the surface 11a side of the wafer 11. The wafer 11 has a disk-shaped single-crystal silicon substrate. However, the single-crystal substrate constituting the wafer 11 is not limited to silicon, and may be formed of a compound semiconductor such as silicon carbide (SiC) or gallium nitride (GaN), or may be formed of other materials.

[0020] As shown in FIG. 2(A), a plurality of dividing planned lines (streets) 13 are set in a grid pattern on the surface 11a side of the wafer 11. Devices 15 such as integrated circuits (ICs) are formed in each rectangular region partitioned by the plurality of dividing planned lines 13.

[0021] The plurality of devices 15 are arranged at the central portion in the radial direction of the wafer 11. In the present embodiment, the region on the surface 11a side where the plurality of devices 15 are arranged is referred to as a device region 17.

[0022] Multiple devices 15 are not formed on the outer periphery of the wafer 11, which forms the ring-shaped reinforcement portion 27. Aside from this condition, there are no restrictions on the type, quantity, shape, structure, size, or arrangement of the multiple devices 15.

[0023] In the radial direction of the wafer 11, an annular outer peripheral excess region 19 exists outside the device region 17. The outer peripheral excess region 19 is a substantially flat region where the device 15 is not formed.

[0024] Figure 2(B) is a perspective view of the back surface 11b of the wafer 11, and Figure 2(C) is a cross-sectional view of the wafer 11. In the thickness direction of the wafer 11, the circular region on the back surface 11b corresponding to the device region 17 has been thinned by grinding, and a circular recess 23 is formed on the back surface 11b of the wafer 11.

[0025] The circular recess 23 is formed, for example, by a processing method called TAIKO (registered trademark). The bottom surface (one surface 23a) of the circular recess 23 corresponds to the back surface 11b of the circular thin plate portion 25. In other words, the back surface 11b of the circular thin plate portion 25 defines one surface 23a of the circular recess 23. The thickness of the circular thin plate portion 25 is, for example, about 50 μm.

[0026] On the outside of the circular thin plate portion 25, a ring-shaped reinforcing portion 27 is formed around the entire circumference of the wafer 11, surrounding the circular thin plate portion 25. The ring-shaped reinforcing portion 27 is the area that remained without being ground down when the circular recess 23 was formed.

[0027] The thickness of the ring-shaped reinforcement portion 27 is greater than the thickness of the circular thin plate portion 25, for example, 700 μm. The inner circumferential surface of the ring-shaped reinforcement portion 27 defines the surface 23b of the circular recess 23. The diameter of the wafer 11 is, for example, 200 mm (8 inches), and the width of the ring-shaped reinforcement portion 27 in the radial direction is, for example, approximately 2.0 mm.

[0028] After forming a circular recess 23 on the back surface 11b side, a circular adhesive tape 29 (see Figure 3) having a larger diameter than the wafer 11 is attached to the back surface 11b side of the wafer 11. The adhesive tape 29 has, for example, a laminated structure of an adhesive layer (glue layer) and a base material layer, with the adhesive layer being attached to the back surface 11b side.

[0029] The adhesive layer has an epoxy, acrylic, or rubber-based adhesive. In this embodiment, the adhesive layer uses an ultraviolet-curing epoxy resin or acrylic resin that hardens when exposed to ultraviolet light. The base layer is formed of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate.

[0030] As shown in Figure 3, the back surface 11b of the circular thin plate portion 25 and the inner circumferential side surface (i.e., side surface 23b) and back surface 11b of the ring-shaped reinforcing portion 27 are attached to the central part of the adhesive tape 29. In addition, one side of the annular frame 31 made of metal is attached to the outer circumference of the adhesive tape 29.

[0031] In this manner, the wafer 11 is supported by the annular frame 31 via the adhesive tape 29 so that its surface 11a is exposed. The wafer 11, the adhesive tape 29, and the annular frame 31 constitute a wafer unit 33.

[0032] After the wafer unit 33 is formed, an annular groove 35 is formed at the boundary between the circular thin plate portion 25 and the ring-shaped reinforcement portion 27 using a cutting device or a laser processing device (neither of which is shown), separating the circular thin plate portion 25 and the ring-shaped reinforcement portion 27 in the radial direction of the wafer 11.

[0033] When using a cutting device, a cutting blade (not shown) is inserted into the boundary between the circular thin plate portion 25 and the ring-shaped reinforcing portion 27, and a circle cut is made in the wafer 11. This forms an annular groove 35.

[0034] Furthermore, when using a laser processing apparatus, the wafer 11 is rotated around a predetermined rotation axis with the focal point of a pulsed laser beam having a wavelength absorbed by the wafer 11 positioned at the boundary between the circular thin plate portion 25 and the ring-shaped reinforcing portion 27. This forms the annular groove 35.

[0035] After the formation of the annular groove 35, a predetermined treatment is performed to reduce the adhesive strength between the ring-shaped reinforcing portion 27 and the adhesive tape 29. In this embodiment, ultraviolet light is irradiated onto the annular region of the adhesive tape 29 that is in contact with the ring-shaped reinforcing portion 27 to reduce the adhesive strength of the adhesive layer. However, ultraviolet light is not irradiated onto the circular region of the adhesive tape 29 that is in contact with the circular thin plate portion 25, and the adhesive strength is maintained.

[0036] Next, the wafer unit 33 is transported to the removal device 2, where the ring-shaped reinforcement portion 27 is removed from the wafer 11. The removal device 2 will now be described with reference to Figure 3. The removal device 2 has a disc-shaped chuck table 4.

[0037] The chuck table 4 has a disc-shaped frame 6 made of metal. A disc-shaped recess is formed on the upper side of the frame 6. A disc-shaped porous plate 8 made of porous ceramics is fixed in the recess.

[0038] The upper surface of the frame 6 and the upper surface of the porous plate 8 are substantially flush, forming a substantially flat holding surface 4a. The bottom surface of the recess of the frame 6 has a plurality of first channels 6a arranged radially and concentrically, and a second channel 6b that penetrates the center of the bottom surface of the frame 6.

[0039] A suction source 10, such as a vacuum pump or ejector, is connected to the second channel 6b. The negative pressure generated by the suction source 10 is transmitted to the upper surface of the porous plate 8 through multiple first channels 6a, second channels 6b, etc.

[0040] The holding surface 4a has an outer diameter 4b that is smaller than the diameter 23c of the circular recess 23. When the back surface 11b of the wafer 11 is held by suction with the holding surface 4a, the holding surface 4a is covered by the circular thin plate portion 25, and the ring-shaped reinforcing portion 27 is located outside the holding surface 4a.

[0041] Multiple clamp units 4c are provided on the outer periphery of the chuck table 4 at approximately equal intervals along the circumferential direction of the frame 6, protruding from the side surface of the frame 6. Each clamp unit 4c grips the annular frame 31 of the wafer unit 33 in the Z-axis direction (height direction, vertical direction) when the wafer 11 is held by suction on the holding surface 4a.

[0042] Above the holding surface 4a, a removal and transport unit 20 is provided for removing the ring-shaped reinforcing portion 27 from the adhesive tape 29. The removal and transport unit 20 has a movable block (not shown) that can move along the Z-axis direction (e.g., height direction, vertical direction) and a planar direction perpendicular to the Z-axis direction (e.g., horizontal direction).

[0043] Each movable block moves along the Z-axis direction and the plane direction by a ball screw type Z-axis direction movement mechanism (not shown) and a plane direction movement mechanism (not shown). The tip of each movable block is provided with a cylindrical rotation axis (a predetermined rotation axis) 22, which is positioned so that its longitudinal portion is aligned with the Z-axis direction.

[0044] The rotating shaft 22 is capable of rotating on its own axis due to a drive source (not shown), such as a motor. The center of the upper surface 24a of a disc-shaped support member 24 is fixed to the lower end of the rotating shaft 22. The support member 24 also rotates as the rotating shaft 22 rotates.

[0045] The support member 24 supports a plurality (three in this embodiment) of arms 26. Each arm 26 has a linear motion mechanism 28. The linear motion mechanism 28 is a ball screw type mechanism that moves the rod 30 forward and backward, and includes a nut portion (not shown) fixed to the rod 30.

[0046] The nut portion is slidably connected to a guide portion (not shown) which is positioned along the longitudinal direction of the rod 30. Furthermore, a screw shaft (not shown), also positioned along the longitudinal direction of the rod 30, is rotatably connected to the nut portion via a plurality of balls (not shown).

[0047] A drive source (not shown), such as a motor, is provided at one end of the screw shaft. When the screw shaft is rotated by the drive source, the rod 30 moves back and forth along its longitudinal direction. Note that the linear motion mechanism 28 is not limited to a ball screw type and may have other mechanisms such as an air cylinder.

[0048] Figure 4 is a top view of the removal and conveying unit 20. As shown in Figure 4, the removal and conveying unit 20 of this embodiment has three rods 30, and the orientation and position of each of the three rods 30 are determined such that the triangle 30a (shown by a dashed line) defined by the extensions of each rod 30 is approximately an equilateral triangle.

[0049] The tip of the rod 30 is fixed to the longitudinal base of a rectangular parallelepiped-shaped movable block 32. The movable block 32 is positioned such that its longitudinal direction and the longitudinal direction of the rod 30 are perpendicular in the horizontal plane.

[0050] A cylindrical shaft portion 34, positioned along the Z-axis, is fixed to the tip of the movable block 32. As shown in Figure 3, a scraper unit 38 is rotatably connected to the lower end of the shaft portion 34 via a bearing 36.

[0051] The scraper unit 38 has a disc-shaped upper scraper member 38a and a lower scraper member 38b. The upper scraper member 38a and the lower scraper member 38b have approximately the same diameter and are arranged concentrically in the Z-axis direction.

[0052] The central parts of the upper scraper member 38a and the lower scraper member 38b are connected by a cylindrical connecting portion 38c. The upper scraper member 38a, the lower scraper member 38b, and the connecting portion 38c are fixed to each other and can rotate indefinitely around the shaft portion 34.

[0053] In this embodiment, the three scraper units 38 are arranged at approximately equal intervals along the circumferential direction of the support member 24 (see Figure 4). In other words, the three scraper units 38 are spaced apart from each other in the circumferential direction of the outer edge (i.e., a predetermined circle) 24b of the support member 24.

[0054] While four or more scraper units 38 may be provided at approximately equal intervals along the circumferential direction of the support member 24, providing three scraper units 38 allows for both minimizing the number of parts in the removal and transport unit 20 and ensuring stable holding of the ring-shaped reinforcing portion 27.

[0055] A sensor unit 42, including one or more optical sensors 40, is provided on the outer periphery of the lower surface 24c of the support member 24. In this embodiment, three optical sensors 40 are arranged at approximately equal intervals along the circumferential direction of the support member 24 (see Figure 4).

[0056] Each optical sensor 40 is positioned near the scraper unit 38. As shown in Figure 4, each optical sensor 40 is positioned between the linear motion mechanism 28 and the scraper unit 38 in a plan view.

[0057] The optical sensor 40 includes, for example, a light projection unit that includes a laser diode for irradiating a laser beam in the visible light band onto a predetermined area. The light projection unit irradiates the laser beam toward the ring-shaped reinforcing portion 27 of the wafer 11, which is held by attraction on the holding surface 4a.

[0058] If a ring-shaped reinforcing portion 27 is present, the laser beam reflected by the ring-shaped reinforcing portion 27 is received by the light-receiving unit of the optical sensor 40. The light-receiving unit includes a photoelectric conversion element such as a photodiode.

[0059] When the laser beam emitted from the light-emitting unit is reflected by the ring-shaped reinforcement section 27, the amount of light received by the light-receiving unit becomes relatively large. Conversely, when the ring-shaped reinforcement section 27 is not present directly beneath the optical sensor 40, the amount of light received by the light-receiving unit becomes relatively small. In this way, the presence or absence of the ring-shaped reinforcement section 27 can be detected according to the amount of light received.

[0060] Each optical sensor 40 may be a camera unit having an LED (Light Emitting Diode) that radially emits light in the visible light band, a focusing lens, and a solid-state image sensor that converts light in the visible light band into photoelectric energy. The solid-state image sensor is, for example, a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor or a CCD (Charge-Coupled Device) image sensor.

[0061] If each optical sensor 40 is a camera unit, the ring-shaped reinforcing portion 27 located below is captured by each optical sensor 40, and the presence or absence of the ring-shaped reinforcing portion 27 is determined by image processing performed by the controller 44, which will be described later.

[0062] The image processing performed by the controller 44 is, for example, binarization, but is not limited to this. The image processing performed by the controller 44 may be any other process that can determine the presence or absence of the ring-shaped reinforcement portion 27.

[0063] The operation of the chuck table 4, suction source 10, removal and transport unit 20, etc., is controlled by the controller 44 (see Figure 3). The controller 44 is composed of a computer including, for example, a processor (processing unit) represented by a CPU (Central Processing Unit) and memory (storage device).

[0064] Memory includes main memory such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), and ROM (Read Only Memory), and auxiliary memory such as flash memory, hard disk drives, and solid-state drives.

[0065] The auxiliary storage device stores software, including a predetermined program. The functions of the controller 44 are realized by operating the processor and other components according to this software.

[0066] Note that in Figure 3, the Z-axis movement mechanism, the planar movement mechanism, and the drive source for the rotation axis 22 are omitted. For convenience, the control of these movement mechanisms and drive sources is indicated by arrows pointing to the rotation axis 22.

[0067] Next, the method for removing the ring-shaped reinforcement portion 27 will be explained according to each step shown in Figure 1. First, as shown in Figure 3, the wafer unit 33 is held by suction using the chuck table 4 (holding step S10).

[0068] Figure 3 shows the holding process S10. In the holding process S10, the back surface 11b side of the circular thin plate portion 25 is held by suction on the holding surface 4a via the adhesive tape 29, and the annular frame 31 is clamped by multiple clamp units 4c.

[0069] After the holding step S10, the ring-shaped reinforcing portion 27 is removed from the adhesive tape 29 by moving it upward using the removal and transport unit 20 (ring-shaped reinforcing portion removal step S20).

[0070] In the ring-shaped reinforcement removal process S20, first, the rod 30 is pulled out so that the entire lower scraper member 38b is positioned outside the wafer 11 in a plan view. Next, the support member 24 is lowered so that the lower scraper member 38b is positioned at a height between the back surface 11b of the ring-shaped reinforcement 27 and the adhesive tape 29.

[0071] Subsequently, by pulling in the rod 30, the lower scraper member 38b is inserted between the back surface 11b of the ring-shaped reinforcement portion 27 and the adhesive tape 29 (i.e., at the interface). In this example, where the width of the ring-shaped reinforcement portion 27 is approximately 2.0 mm, the insertion amount is, for example, 1.6 mm inward from the edge of the wafer 11. However, the insertion amount is not limited to this value.

[0072] Figure 5(A) is a partial cross-sectional side view showing the insertion of the lower scraper member 38b. For convenience, the controller 44 is omitted from the partial cross-sectional side views of the removal and transport unit 20 from Figure 5(A) onward.

[0073] Next, as shown in Figure 5(B), with the lower scraper member 38b inserted between the back surface 11b of the ring-shaped reinforcing portion 27 and the adhesive tape 29, the support member 24 is rotated around the rotation axis 22, thereby rotating the scraper unit 38 around the wafer 11. At this time, each scraper unit 38 can also rotate around the shaft portion 34.

[0074] Figure 5(B) is a perspective view showing the movement of the scraper unit 38 along the outer circumference of the wafer 11. In this example, the three scraper units 38 are separated by approximately 120° in the circumferential direction of the holding surface 4a, so the support member 24 is rotated by 120° or more.

[0075] For example, the rotation speed of the scraper unit 38 is set to, for example, 10° / s, and each scraper unit 38 is rotated 140° around the wafer 11 over 14 seconds.

[0076] In the ring-shaped reinforcement removal process S20, after inserting and rotating the scraper unit 38, the removal and transport unit 20 is raised to move the ring-shaped reinforcement 27 upward so that it moves away from the chuck table 4.

[0077] Figure 6(A) is a partial cross-sectional side view showing the movement of the ring-shaped reinforcing portion 27, and Figure 6(B) is a perspective view showing the movement of the ring-shaped reinforcing portion 27. The upward speed of the scraper unit 38 is, for example, 0.14 mm / s.

[0078] Although the adhesive strength of the adhesive tape 29 has been reduced, it is not possible to completely eliminate the adhesive strength. Therefore, when lifting the ring-shaped reinforcing part 27, the ring-shaped reinforcing part 27, which has been peeled off the adhesive tape 29, may spring up forcefully due to the recoil.

[0079] However, even if the ring-shaped reinforcing portion 27 rises rapidly, the upper scraper member 38a can keep the rise of the ring-shaped reinforcing portion 27 within a predetermined range. Therefore, the fall of the ring-shaped reinforcing portion 27 can be prevented.

[0080] In this embodiment, the upper scraper member 38a and the lower scraper member 38b have the same structure, shape, and size, but the upper scraper member 38a does not necessarily function as a scraper.

[0081] The upper scraper member 38a may be a plate member that functions as a canopy, considering its function. In order to function as a canopy, the plate member only needs to have a projection from the connecting portion 38c in a plan view that is approximately the same as that of the lower scraper member 38b, and is preferably disc-shaped, but may also be other polygonal shapes.

[0082] After the ring-shaped reinforcement removal step S20, the sensor unit 42 is used to detect whether the ring-shaped reinforcement 27 removed from the adhesive tape 29 is being held by three or more scraper units 38 (first detection step S30). Figure 7 is a partial cross-sectional side view showing the first detection step S30.

[0083] In the first detection step S30, the presence or absence of the ring-shaped reinforcing portion 27 directly beneath each optical sensor 40 is detected using the reflected light or image described above. In this embodiment, three optical sensors 40 are used to detect the presence or absence of the ring-shaped reinforcing portion 27 at three locations on the ring-shaped reinforcing portion 27.

[0084] In addition, if a part of the ring-shaped reinforcing portion 27 is missing, an error may occur in which the ring-shaped reinforcing portion 27 is not detected by the optical sensor 40. In this case, the controller 44 controls the speaker (not shown), display (not shown), LED lamp (not shown), etc., provided on the removal device 2 to notify the operator of the removal device 2 of the error.

[0085] For example, the operator is notified of an error in the removal device 2 through an alarm or voice message from a speaker, a warning display on the screen, or the illumination or flashing of an LED lamp. If an error is notified, the operator temporarily stops the operation of the removal device 2.

[0086] Then, if the ring-shaped reinforcement portion 27 is held by the three scraper units 38, the operator clears the error and restarts the operation of the removal and transport unit 20.

[0087] Furthermore, if the ring-shaped reinforcing portion 27 is not held by the removal and transport unit 20, the ring-shaped reinforcing portion 27 may not be detected by the optical sensor 40, resulting in an error. In this case, when an error is notified, the worker manually removes the ring-shaped reinforcing portion 27.

[0088] After the first detection step S30, the removal and transport unit 20 is moved by the planar movement mechanism to transport the ring-shaped reinforcement part 27 to the collection box 46 (see Figure 8) (transport step S40). Figure 8 is a partial cross-sectional side view showing the transport step S40.

[0089] The collection box 46 is positioned differently from the chuck table 4 in the planar direction. The removal and transport unit 20 moves to directly above the collection box 46 while holding the ring-shaped reinforcement portion 27 with three or more scraper units 38, and then pulls out each rod 30.

[0090] As a result, the ring-shaped reinforcing part 27 is released from the scraper unit 38 and falls due to its own weight. The ring-shaped reinforcing part 27 falls into the collection box 46 through the opening 46a of the collection box 46.

[0091] After the transport process S40, the removal transport unit 20 returns from the collection box 46 to directly above the chuck table 4. Then, the sensor unit 42 is positioned on the outer circumference of the wafer 11 from which the ring-shaped reinforcement portion 27 has been removed to detect whether or not there is any partial remaining ring-shaped reinforcement portion 27 (second detection process S50). Figure 9 is a partial cross-sectional side view showing the second detection process S50.

[0092] In the second detection step S50, the sensor unit 42 is moved along the outer circumference of the wafer 11 by rotating the support member 24 around the rotation axis 22. For example, each optical sensor 40 is rotated 120° over 12 seconds at a rotation speed of 10° / s.

[0093] This allows for the detection of the presence or absence of partial remaining ring-shaped reinforcement portion 27 (i.e., remaining chipped ring-shaped reinforcement portion 27) around the entire circumference of the wafer 11. Figures 10(A) and 10(B) show the chips 27a formed on the ring-shaped reinforcement portion 27 after the ring-shaped reinforcement portion removal process S20.

[0094] Figure 10(A) is a top view showing an example of a chip 27a in the ring-shaped reinforcing portion 27, and Figure 10(B) is a top view showing another example of a chip 27a in the ring-shaped reinforcing portion 27. When a chip 27a is formed, a chipped portion corresponding to the shape of the chip 27a remains on the adhesive tape 29.

[0095] If a missing piece is detected in the second detection step S50, the operator is notified of the error using a speaker, display, LED lamp, etc., similar to the first detection step S30. In this case, for example, the operator manually removes the remaining missing piece of the ring-shaped reinforcement part 27.

[0096] In this embodiment, by utilizing multiple sensor units 42, it is possible to detect whether or not the ring-shaped reinforcing portion 27 is held by three or more lower scraper members 38b (first detection step S30), and further, whether or not there is a partial remaining portion of the ring-shaped reinforcing portion 27 (second detection step S50).

[0097] Therefore, if any portion of the ring-shaped reinforcing portion 27 remains on the adhesive tape 29, the remainder of the ring-shaped reinforcing portion 27 can be removed so as not to interfere with subsequent cutting or other processing steps. Furthermore, the structure, method, etc., according to the above embodiment can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0098] 2:Removal device 4: Chuck table, 4a: Holding surface, 4b: Outer diameter, 4c: Clamping unit 6: Frame, 6a: First channel, 6b: Second channel, 8: Porous plate, 10: Suction source 11: Wafer, 11a: Front side, 11b: Back side, 13: Planned splitting line 15: Device, 17: Device area, 19: Peripheral surplus area 20: Removal and transport unit, 22: Rotating shaft (predetermined rotating shaft) 23: Circular recess, 23a: One side, 23b: Side, 23c: Diameter 24: Support member, 24a: Top surface, 24b: Outer periphery, 24c: Bottom surface 25: Circular thin plate section, 27: Ring-shaped reinforcing section, 27a: Chipped section 26: Arm, 28: Linear motion mechanism, 30: Rod, 30a: Triangle 29: Adhesive tape, 31: Ring frame 32: Moving block, 34: Shaft, 36: Bearing 33: Wafer unit, 35: Annular groove 38: Scraper unit, 38a: Upper scraper member 38b: Lower scraper member (scraper member), 38c: Connection part 40: Optical sensor, 42: Sensor unit 44: Controller, 46: Collection box, 46a: Opening S10: Holding process, S20: Ring-shaped reinforcement removal process, S30: First detection process S40: Conveying process, S50: Second detection process

Claims

1. A removal method for removing a ring-shaped reinforcing portion located on the outer periphery of a wafer that constitutes a wafer unit, The wafer unit is, A wafer comprising a circular thin plate portion defining one side of a circular recess formed on the back side, and a ring-shaped reinforcing portion defining the side of the circular recess and being thicker than the circular thin plate portion, wherein an annular groove is formed separating the circular thin plate portion and the ring-shaped reinforcing portion, An adhesive tape with its central portion attached to the back side of the wafer, The annular frame has the outer periphery of the adhesive tape attached to one surface of the annular frame, A holding step of suction-holding the wafer unit with a chuck table having a holding surface with a diameter smaller than the diameter of the circular recess, A ring-shaped reinforcement removal step involves inserting three or more disc-shaped scraper members, each spaced apart from the others in the circumferential direction of a predetermined circle, between the ring-shaped reinforcement and the adhesive tape, moving them along the outer circumference of the wafer, and then moving the ring-shaped reinforcement upward so as to move it away from the chuck table, thereby removing the ring-shaped reinforcement from the adhesive tape. After the ring-shaped reinforcement removal step, a first detection step is performed to detect whether the ring-shaped reinforcement is held by the three or more scraper members using a sensor unit that includes one or more optical sensors provided on the outer circumference of the lower side of a disc-shaped support member that supports the three or more scraper members, After the first detection step, a transport step is performed to transport the ring-shaped reinforcing portion, which is held by the three or more scraper members, to a collection box. A removal method characterized by comprising: a second detection step, after the transport step, positioning the sensor unit on the outer circumference of the wafer from which the ring-shaped reinforcing portion has been removed, and detecting whether or not a portion of the ring-shaped reinforcing portion remains.

2. The removal method according to claim 1, characterized in that the second detection step involves moving the sensor unit along the outer circumference of the wafer by rotating the support member around a predetermined axis of rotation, and detecting whether or not there is a partial remaining portion of the ring-shaped reinforcing portion around the entire circumference of the wafer.

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