Wafer Processing Method

Abstract

To provide a processing method for a wafer capable of easily removing a reinforcement part remaining in an outer peripheral part of the wafer.SOLUTION: The present invention relates to a processing method for a wafer for processing the wafer comprising: a device area in which devices are formed respectively in a plurality of regions defined by a plurality of predetermined dividing lines arrayed in a grid shape so as to cross each other, on a front side; a recess formed, on a rear side, in an area corresponding to the device area; and an annular reinforcement part enclosing the device area and the recess in an outer peripheral part. The processing method includes: a cutting step of dividing the device area into a plurality of device chips and forming a cutting groove in the reinforcement part; a dividing step of dividing the reinforcement part with the cutting groove defined as a starting point; and removing step of injecting a fluid toward the reinforcement part from a predetermined injection position which is located outside of the wafer, thereby scattering, toward an opposite side of the injection position, and removing the divided reinforcement parts.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a wafer processing method. [Background technology]

[0002] In the manufacturing process of device chips, a wafer is used that has a surface side with device regions, each of which has a device formed in a plurality of regions partitioned by a plurality of planned division lines (streets) arranged in a grid pattern. By dividing this wafer along the planned division lines, a plurality of device chips, each of which has a device, are obtained. The device chips are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] In recent years, device chips are required to be thinned as electronic devices become smaller. Therefore, a process to thin a wafer is sometimes performed before dividing the wafer. To thin a wafer, a grinding device is used that includes a chuck table for holding a workpiece and a grinding unit to which a grinding wheel having multiple grinding stones is attached. The wafer is held by the chuck table, and the grinding stone is brought into contact with the back side of the wafer while rotating the chuck table and the grinding wheel, thereby grinding and thinning the wafer.

[0004] When a wafer is thinned by grinding, the rigidity of the wafer decreases, making the wafer more susceptible to damage during handling (transportation, etc.) of the wafer after grinding. Therefore, a method has been proposed in which only the area of ​​the back side of the wafer that overlaps with the device area is ground to thin it (see Patent Document 1). With this method, the center of the wafer is thinned to form a recess, while the outer periphery of the wafer is not thinned and remains thick, remaining as an annular reinforcing part. This suppresses the decrease in rigidity of the wafer after grinding.

[0005] The thinned wafer is finally divided into a plurality of device chips using a cutting device or the like that cuts the workpiece with an annular cutting blade. At this time, the wafer is cut along the planned division line after the annular reinforcing portion remaining on the outer periphery is removed. For example, Patent Document 2 discloses a method in which the outer periphery of the wafer is cut into an annular shape with a cutting blade to separate the device region and the reinforcing portion (annular convex portion), and then the reinforcing portion is lifted and removed by a claw assembly having multiple claws. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-19379 A [Patent Document 2] JP 2011-61137 A Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, the annular reinforcing portion remaining on the outer periphery of the wafer is separated and removed from the wafer in the wafer processing process. However, immediately after the reinforcing portion is separated from the wafer, the reinforcing portion is arranged close to the device region so as to surround the central portion (device region) of the wafer that has been thinned and has a reduced rigidity. Therefore, when removing the reinforcing portion, the annular reinforcing portion may accidentally come into contact with the device region, causing damage to the device region.

[0008] Therefore, in order to properly remove the reinforcement portion, it is necessary to hold the reinforcement portion carefully so that it does not interfere with the device region, and to lift the reinforcement portion without causing the reinforcement portion to shake or shift. As a result, the structure of the mechanism (claw assembly, etc.) used to remove the reinforcement portion becomes complicated, increasing costs. In addition, the work time required to remove the reinforcement portion becomes longer, reducing work efficiency.

[0009] The present invention has been made in view of the above problems, and has an object to provide a wafer processing method capable of easily removing a reinforcing portion remaining on the outer periphery of a wafer. [Means for solving the problem]

[0010] According to one aspect of the present invention, there is provided a wafer processing method for processing a wafer having a surface side including device regions in which devices are formed in a plurality of regions partitioned by a plurality of planned division lines arranged in a lattice pattern so as to intersect with each other, a back side including recesses formed in regions corresponding to the device regions, and an annular reinforcing portion surrounding the device regions and the recesses on an outer periphery, the method comprising the steps of: a tape adhering step of adhering an adhesive tape to the back side of the wafer along the recesses and the reinforcing portion; a holding step of holding a bottom surface of the recesses via the adhesive tape using a first chuck table; a cutting step of cutting the wafer along the planned division lines with a cutting blade to divide the device region into a plurality of device chips and form cutting grooves in the reinforcing portion; a dividing step of applying an external force to the reinforcing portion to divide the reinforcing portion from the cutting grooves as starting points; and a removing step of spraying a fluid from a predetermined spraying position located outside the wafer toward the reinforcing portion, thereby scattering and removing the divided reinforcing portion toward an opposite side from the spraying position. In the removal step, the fluid is sprayed along a tangential direction of the outer periphery of the wafer. A method for processing a wafer is provided. According to another aspect of the present invention, there is provided a wafer processing method for processing a wafer having a surface side with device regions in which devices are formed in a plurality of regions partitioned by a plurality of planned dividing lines arranged in a lattice pattern so as to intersect with each other, a back side with recesses formed in regions corresponding to the device regions, and an annular reinforcing portion surrounding the device regions and the recesses on an outer periphery, the method including a tape applying step of applying an adhesive tape to the back side of the wafer along the recesses and the reinforcing portion, a holding step of holding a bottom surface of the recesses via the adhesive tape by a first chuck table, and cutting the wafer along the planned dividing lines by a cutting blade to form the device regions. The present invention provides a wafer processing method comprising: a cutting step for dividing a region into a plurality of device chips and forming a cutting groove in the reinforcing portion; a dividing step for dividing the reinforcing portion starting from the cutting groove by applying an external force to the reinforcing portion; and a removing step for spraying a fluid toward the reinforcing portion from a predetermined spraying position located outside the wafer, thereby scattering the divided reinforcing portion in the direction opposite to the spraying position, wherein a nozzle and a recovery mechanism are arranged to sandwich the reinforcing portion of the wafer, and the fluid is sprayed from the nozzle toward the reinforcing portion, causing the divided reinforcing portion to be scattered toward the recovery mechanism and recovered by the recovery mechanism in the removing step.

[0011] Preferably, , applicable In the dividing step, the wafer is supported by a second chuck table having a concave-convex shape at a position corresponding to the reinforcing portion of the wafer, and the adhesive tape is sucked by the second chuck table, so that the adhesive tape is arranged along the concave-convex shape to divide the reinforcing portion. 。 Effect of the Invention

[0012] In a wafer processing method according to one aspect of the present invention, a cutting step divides a device region into a plurality of device chips, and a cutting groove is formed in a reinforcing portion. Then, in a dividing step, an external force is applied to the reinforcing portion, and the reinforcing portion is divided starting from the cutting groove. This makes it possible to easily remove the reinforcing portion from the wafer by a simple method of spraying a fluid onto the divided reinforcing portion.

[0013] In addition, in a wafer processing method according to one aspect of the present invention, a fluid is sprayed from a predetermined spray position located on the outside of the wafer toward the reinforcing part, causing the divided reinforcing part (multiple chips) to scatter in the direction opposite to the spray position. This makes it possible to prevent the chips from scattering in random directions from the wafer, and makes it easy to collect the chips. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1(A) is a perspective view showing the front side of a wafer, and FIG. 1(B) is a perspective view showing the back side of the wafer. [Diagram 2] FIG. 2(A) is a perspective view showing a wafer to which an adhesive tape has been adhered, and FIG. 2(B) is a cross-sectional view showing the wafer to which the adhesive tape has been adhered. [Diagram 3] FIG. [Figure 4] 2 is a cross-sectional view showing a wafer held by a chuck table. [Diagram 5] FIG. 5(A) is a cross-sectional view showing a wafer cut along a first direction, and FIG. 5(B) is a cross-sectional view showing a wafer cut along a second direction. [Figure 6] FIG. 2 is a perspective view showing an external force imparting unit. [Figure 7] FIG. 7(A) is a cross-sectional view showing a wafer placed on a chuck table, and FIG. 7(B) is a cross-sectional view showing the wafer sucked by the chuck table. [Figure 8] FIG. 13 is a perspective view showing a wafer in which a reinforcing portion is divided into a plurality of chips. [Figure 9] FIG. 11 is a perspective view showing a wafer in a removing step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment according to one aspect of the present invention will be described below with reference to the accompanying drawings. First, a configuration example of a wafer processed by a wafer processing method according to this embodiment will be described. Fig. 1(A) is a perspective view showing the front side of a wafer 11, and Fig. 1(B) is a perspective view showing the back side of the wafer 11.

[0016] The wafer 11 is a disk-shaped substrate made of a semiconductor such as silicon, and has a front surface 11a and a back surface 11b that are generally parallel to each other. The wafer 11 is partitioned into a plurality of rectangular regions by a plurality of planned division lines (streets) 13 that are arranged in a lattice pattern so as to intersect with each other. In addition, devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) are formed in each of the regions partitioned by the planned division lines 13 on the front surface 11a side of the wafer 11.

[0017] The wafer 11 includes, on the front surface 11a side, a substantially circular device region 17a in which a plurality of devices 15 are formed, and an annular peripheral surplus region 17b surrounding the device region 17a. The peripheral surplus region 17b corresponds to an annular region of a predetermined width (e.g., about 2 mm) including the outer periphery of the front surface 11a. In Fig. 1(A), the boundary between the device region 17a and the peripheral surplus region 17b is indicated by a two-dot chain line.

[0018] There are no limitations on the material, shape, structure, size, etc. of the wafer 11. For example, the wafer 11 may be a substrate made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, etc. There are also no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 15.

[0019] A plurality of device chips each including a device 15 are manufactured by dividing the wafer 11 into a lattice shape along the planned dividing lines 13. In addition, by performing a thinning process on the wafer 11 before dividing, it is possible to obtain thinned device chips.

[0020] For example, a grinding device is used to thin the wafer 11. The grinding device includes a chuck table (holding table) that holds the wafer 11, and a grinding unit that grinds the wafer 11. An annular grinding wheel including a plurality of grinding stones is attached to the grinding unit. The wafer 11 is held by the chuck table, and the grinding stones are brought into contact with the back surface 11b of the wafer 11 while the chuck table and the grinding wheel are both rotated, thereby grinding the back surface 11b of the wafer 11 and thinning the wafer 11.

[0021] If the entire back surface 11b side of the wafer 11 is ground, the entire wafer 11 is thinned, the rigidity of the wafer 11 is reduced, and the wafer 11 becomes more susceptible to damage during handling (transportation, etc.) of the ground wafer 11. For this reason, the thinning process (grinding) is sometimes performed only on the center portion of the back surface 11b side of the wafer 11.

[0022] 1(B), only the central portion of the wafer 11 is ground and thinned. As a result, a circular recess (groove) 19 is formed on the back surface 11b of the wafer 11. The recess 19 is provided at a position corresponding to the device region 17a. For example, the size (diameter) of the recess 19 is set to be approximately the same as the size (diameter) of the device region 17a, and the recess 19 is formed so as to overlap multiple devices 15.

[0023] The recess 19 includes a bottom surface 19a that is generally parallel to the front surface 11a and the back surface 11b of the wafer 11, and an annular side surface (inner wall) 19b that is generally perpendicular to the bottom surface 19a and connected to the bottom surface 19a and the back surface 11b. In addition, an annular reinforcing portion (convex portion) 21 that corresponds to an area that has not been subjected to the thinning process (grinding process) remains on the outer periphery of the wafer 11. The reinforcing portion 21 includes the outer periphery excess region 17b and surrounds the device region 17a and the recess 19.

[0024] By thinning only the central portion of the wafer 11, the outer periphery (reinforcing portion 21) of the wafer 11 is maintained in a thick state. This prevents the rigidity of the wafer 11 from decreasing, making the wafer 11 less susceptible to damage or the like. In other words, the reinforcing portion 21 functions as a reinforcing region that reinforces the wafer 11.

[0025] Next, a specific example of a wafer processing method for dividing the above-mentioned wafer 11 into a plurality of device chips will be described. In this embodiment, first, an adhesive tape is attached to the back surface 11b side of the wafer 11 (tape attachment step). Fig. 2(A) is a perspective view showing the wafer 11 to which the adhesive tape 23 is attached, and Fig. 2(B) is a cross-sectional view showing the wafer 11 to which the adhesive tape 23 is attached.

[0026] An adhesive tape 23 having a size capable of covering the entire back surface 11b of the wafer 11 is attached to the back surface 11b of the wafer 11. For example, a circular adhesive tape 23 having a diameter larger than that of the wafer 11 is attached so as to cover the back surface 11b of the wafer 11.

[0027] A flexible film including a circular substrate and an adhesive layer (glue layer) provided on the substrate can be used as the adhesive tape 23. For example, the substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. Also, an ultraviolet-curing resin that is cured by irradiation with ultraviolet rays can be used as the adhesive layer.

[0028] The adhesive tape 23 is attached along the contour of the back surface 11b side of the wafer 11. That is, as shown in Fig. 2(B), the adhesive tape 23 is attached along (following) the bottom surface 19a and the side surface 19b of the recess 19 and the back surface (lower surface) of the reinforcing portion 21. Note that, although Fig. 2(B) shows an example in which the adhesive tape 23 is attached so as to be in close contact with the bottom surface 19a and the side surface 19b, there may be slight gaps between the adhesive tape 23 and the outer periphery of the bottom surface 19a and between the adhesive tape 23 and the side surface 19b.

[0029] An annular frame 25 made of metal such as SUS (stainless steel) is attached to the outer periphery of the adhesive tape 23. A circular opening 25a capable of accommodating the wafer 11 is provided in the center of the frame 25. The wafer 11 is supported by the frame 25 via the adhesive tape 23 while being placed inside the opening 25a. In this way, a frame unit (work set) is formed in which the wafer 11, the adhesive tape 23, and the frame 25 are integrated.

[0030] The wafer 11 with the adhesive tape 23 attached thereto is cut by a cutting device. Fig. 3 is a perspective view showing the cutting device 2. In Fig. 3, the X-axis direction (processing feed direction, first horizontal direction) and the Y-axis direction (indexing feed direction, second horizontal direction) are perpendicular to each other. The Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction. The cutting device 2 includes a chuck table (holding table) 4 that holds the wafer 11, and a cutting unit 12 that cuts the wafer 11 held by the chuck table 4.

[0031] The upper surface of the chuck table 4 is a flat surface formed generally parallel to the X-axis direction and the Y-axis direction, and constitutes a circular holding surface 4a (see FIG. 4) that holds the wafer 11. In addition, the chuck table 4 is connected to a ball screw type moving mechanism (not shown) that moves the chuck table 4 along the X-axis direction, and a rotational drive source (not shown) such as a motor that rotates the chuck table 4 around a rotation axis generally parallel to the Z-axis direction.

[0032] A cutting unit 12 that cuts the wafer 11 is disposed above the chuck table 4. The cutting unit 12 includes a hollow cylindrical housing 14, and a cylindrical spindle (not shown) disposed along the Y-axis direction is accommodated in the housing 14. A tip end (one end) of the spindle is exposed to the outside of the housing 14, and a rotation drive source (not shown) such as a motor is connected to a base end (the other end) of the spindle.

[0033] An annular cutting blade 16 is attached to the tip of the spindle. The cutting blade 16 rotates about a rotation axis roughly parallel to the Y-axis direction by power transmitted from a rotation drive source via the spindle.

[0034] As the cutting blade 16, for example, a hub-type cutting blade (hub blade) is used. The hub blade is configured by integrating an annular base made of metal or the like with an annular cutting edge formed along the outer periphery of the base. The cutting edge of the hub blade is configured by an electroformed grinding stone in which abrasive grains made of diamond or the like are fixed by a binder such as a nickel plating layer. Also, a washer-type cutting blade (washer blade) may be used as the cutting blade 16. The washer blade is configured by an annular cutting edge in which abrasive grains made of diamond or the like are fixed by a binder such as metal, ceramics, resin, or the like.

[0035] The cutting blade 16 attached to the tip of the spindle is covered by a blade cover 18 fixed to the housing 14. The blade cover 18 includes a connection part 20 connected to a tube (not shown) through which a liquid (cutting fluid) such as pure water is supplied, and a pair of nozzles 22 connected to the connection part 20 and disposed on both sides (front and back sides) of the cutting blade 16. Each of the pair of nozzles 22 is formed with an injection port (not shown) that opens toward the cutting blade 16.

[0036] When cutting the wafer 11 with the cutting blade 16, cutting fluid is supplied to the connection part 20, and the cutting fluid is sprayed from the nozzles of the pair of nozzles 22 toward both sides (front and back sides) of the cutting blade 16. This cools the wafer 11 and the cutting blade 16, and washes away chips (cutting chips) generated by the cutting process.

[0037] A ball screw type moving mechanism (not shown) that moves the cutting unit 12 is connected to the cutting unit 12. This moving mechanism moves the cutting unit 12 along the Y-axis direction and raises and lowers it along the Z-axis direction.

[0038] When cutting the wafer 11, first, the wafer 11 is held by the chuck table 4 (first chuck table) (holding step). FIG. 4 is a cross-sectional view showing the wafer 11 held by the chuck table 4.

[0039] The chuck table 4 includes a cylindrical frame (main body) 6 made of metal, glass, ceramics, resin, or the like. A recess (groove) 6b that is circular in plan view is formed on the upper surface 6a side of the frame 6, and a disk-shaped holding member 8 is fitted into the recess 6b. The holding member 8 is a member made of a porous material such as porous ceramics, and includes holes (suction paths) therein that communicate from the upper surface to the lower surface of the holding member 8.

[0040] The upper surface 6a of the frame 6 and the upper surface 8a of the holding member 8 are disposed on approximately the same plane and constitute the holding surface 4a of the chuck table 4. The upper surface 8a of the holding member 8 constitutes a circular suction surface that sucks the wafer 11. The holding surface 4a is connected to a suction source (not shown) such as an ejector via a flow path (not shown) formed inside the holding member 8 and the frame 6, a valve (not shown), and the like.

[0041] The wafer 11 is placed on the chuck table 4 so that the front surface 11a side is exposed upward. The chuck table 4 is configured so that the holding surface 4a can hold the bottom surface 19a of the recess 19 of the wafer 11. Specifically, the diameter of the holding surface 4a is smaller than the diameter of the recess 19, and the holding surface 4a side of the chuck table 4 is fitted into the recess 19. As a result, the bottom surface 19a of the recess 19 is supported by the holding surface 4a via the adhesive tape 23.

[0042] In addition, a plurality of clamps 10 that grip and fix a frame 25 are provided around the periphery of the chuck table 4. After the wafer 11 is placed on the chuck table 4, the frame 25 is fixed by the plurality of clamps 10.

[0043] When the suction force (negative pressure) of the suction source is applied to the holding surface 4a with the wafer 11 placed on the chuck table 4, the area of ​​the adhesive tape 23 attached to the bottom surface 19a of the recess 19 is sucked to the holding surface 4a. As a result, the bottom surface 19a of the recess 19 is sucked and held by the chuck table 4 via the adhesive tape 23.

[0044] Next, the wafer 11 is cut along the intended dividing lines 13 (see FIG. 3, etc.) by the cutting blade 16 (cutting step). In the cutting step, the wafer 11 is cut along the intended dividing lines 13 parallel to a first direction and along the intended dividing lines 13 parallel to a second direction intersecting the first direction.

[0045] 5(A) is a cross-sectional view showing a wafer 11 cut along a first direction. First, the chuck table 4 is rotated to align the length direction of one planned dividing line 13 parallel to the first direction with the X-axis direction. In addition, the position of the cutting unit 12 in the Y-axis direction is adjusted so that the cutting blade 16 is positioned on an extension line of the one planned dividing line 13.

[0046] Furthermore, the height of the cutting unit 12 is adjusted so that the lower end of the cutting blade 16 is positioned below the bottom surface 19a of the recess 19. For example, the lower end of the cutting blade 16 is positioned below the upper surface of the adhesive tape 23 attached to the bottom surface 19a of the recess 19 and above the holding surface 4a (the lower surface of the adhesive tape 23). The difference in height between the surface 11a of the wafer 11 and the lower end of the cutting blade 16 at this time corresponds to the cutting depth of the cutting blade 16 into the wafer 11.

[0047] Then, while rotating the cutting blade 16, the chuck table 4 is moved along the X-axis direction. As a result, the chuck table 4 and the cutting blade 16 move relatively along the X-axis direction (processing feed), and the cutting blade 16 cuts into the front surface 11a side of the wafer 11 along one of the planned division lines 13.

[0048] At this time, the cutting depth of the cutting blade 16 is greater than the thickness of the central part (device region 17a) of the wafer 11, and is smaller than the thickness of the peripheral part (reinforcement part 21) of the wafer 11. Therefore, in the device region 17a of the wafer 11, a cut edge (kerf) extending from the front surface 11a to the bottom surface 19a is formed along one of the planned division lines 13. Meanwhile, in the reinforcing part 21 of the wafer 11, a cutting groove 11c having a depth corresponding to the cutting depth of the cutting blade 16 is formed along one of the planned division lines 13.

[0049] Thereafter, the cutting blade 16 is moved (indexed feed) in the Y-axis direction by the distance of the dividing lines 13 to cut the wafer 11 along the other dividing lines 13. By repeating this procedure, the wafer 11 is cut along all the dividing lines 13 that are parallel to the first direction.

[0050] Next, the chuck table 4 is rotated 90° to align the length directions of the dividing lines 13 parallel to the second direction with the X-axis direction. Then, by following the same procedure, the wafer 11 is cut along all the dividing lines 13 parallel to the second direction. Fig. 5(B) is a cross-sectional view showing the wafer 11 cut along the second direction.

[0051] When the wafer 11 is cut along all the dividing lines 13, the device region 17a of the wafer 11 is divided along the dividing lines 13 to obtain a plurality of device chips 27 (see FIG. 6), each of which includes a device 15. In addition, cutting grooves 11c are formed along the dividing lines 13 on the upper surface (front surface) side of the reinforcing portion 21.

[0052] Next, an external force is applied to the reinforcing portion 21, so that the reinforcing portion 21 is divided from the cut groove 11c as a starting point (division step). In this embodiment, the external force is applied to the reinforcing portion 21 by sucking the adhesive tape 23 with a second chuck table.

[0053] 6 is a perspective view showing the external force imparting unit 30. The external force imparting unit 30 is a mechanism for imparting an external force to the wafer 11, and is provided inside or outside the cutting device 2 (see FIG. 3). The external force imparting unit 30 includes a chuck table (holding table) 32 for holding the wafer 11.

[0054] The upper surface of the chuck table 32 forms a circular holding surface for holding the wafer 11. In addition, the chuck table 32 is connected to a rotation drive source (not shown) such as a motor that rotates the chuck table 32 around a rotation axis that is approximately parallel to the vertical direction.

[0055] The chuck table 32 includes a cylindrical frame (main body) 34 made of metal, glass, ceramics, resin, or the like. A recess (groove) 34b that is circular in plan view is formed in the center of an upper surface 34a of the frame 34, and a disk-shaped holding member 36 is fitted into the recess 34b. The holding member 36 is a member made of a porous material such as porous ceramics, and includes holes (suction paths) therein that communicate from the upper surface to the lower surface of the holding member 36.

[0056] The upper surface of the holding member 36 forms a circular suction surface 36a that suction-holds the wafer 11. The suction surface 36a and the upper surface 34a of the frame 34 are disposed on approximately the same plane.

[0057] The chuck table 32 has projections and recesses at positions corresponding to the reinforcing portions 21 of the wafer 11. For example, the frame 34 is formed so that the upper surface 34a overlaps with the reinforcing portions 21 when the wafer 11 is placed on the chuck table 32. The upper surface 34a of the frame 34 is provided with a plurality of projections (protrusions) 38 that protrude upward from the upper surface 34a. Although the projections 38 formed in a rectangular parallelepiped shape are shown in FIG. 6, the shape of the projections 38 is not limited.

[0058] The multiple protrusions 38 are arranged at approximately equal intervals along the circumferential direction of the frame 34. The upper surface 34a of the frame 34 and the protrusions 38 form an annular region having periodic projections and recesses.

[0059] Furthermore, annular grooves 40a, 40b that open on the upper surface 34a are provided on the upper surface 34a side of the frame 34. For example, the grooves 40a, 40b are formed concentrically on both sides (the outer and inner sides in the radial direction of the frame 6) of the multiple protrusions 38. The grooves 40a and 40b are connected to each other via multiple grooves 40c formed along the radial direction of the frame 6.

[0060] The holding member 36 is connected to a suction source 44 via a flow path (not shown) and a valve 42a provided inside the frame 34. The grooves 40a, 40b, and 40c are connected to the suction source 44 via a flow path (not shown) and a valve 42b provided inside the frame 34. As the suction source 44, for example, an ejector is used.

[0061] The wafer 11 is placed on the chuck table 32 so that the reinforcing portion 21 overlaps with the upper surface 34a of the frame 34. In this way, the reinforcing portion 21 of the wafer 11 is supported by the multiple protrusions 38 via the adhesive tape 23.

[0062] Fig. 7(A) is a cross-sectional view showing the wafer 11 placed on the chuck table 32. For convenience of explanation, Fig. 7(A) shows only the cross-sectional shapes of the wafer 11, the adhesive tape 23, the frame 25, and the chuck table 32. When the valves 42a and 42b are opened with the wafer 11 placed on the chuck table 32, the suction force (negative pressure) of the suction source 44 acts on the suction surface 36a and the grooves 40a, 40b, and 40c, and the wafer 11 is sucked and held by the chuck table 32 via the adhesive tape 23.

[0063] 7(B) is a cross-sectional view showing the wafer 11 sucked by the chuck table 32. The areas of the adhesive tape 23 attached to the multiple device chips 27 are sucked and come into contact with the suction surface 36a. Also, the areas of the adhesive tape 23 attached to the back surface 11b side of the outer periphery (reinforcement portion 21) of the wafer 11 and the areas nearby are sucked into the grooves 40a, 40b and come into contact with the upper surface 34a of the frame 34.

[0064] Here, as shown in FIG. 6, the upper surface 34a of the frame 34 has a periodic unevenness formed in a ring shape by a plurality of convex portions 38. Therefore, when negative pressure is applied to the grooves 40a and 40b, the area of ​​the adhesive tape 23 attached to the outer periphery of the wafer 11 is deformed along the upper surface 34a of the frame 34 and the convex portions 38, and becomes wavy. Then, the area of ​​the reinforcing portion 21 that is not supported by the convex portions 38 is pulled toward the upper surface 34a of the frame 34 by the adhesive tape 23, and moves so as to enter between the adjacent convex portions 38. As a result, a shear stress acts on the reinforcing portion 21. That is, an external force is applied to the reinforcing portion 21 by sucking the adhesive tape 23 by the chuck table 32.

[0065] When an external force is applied to the reinforcing portion 21, a crack is generated from the cutting groove 11c formed in the reinforcing portion 21 and progresses in the thickness direction of the reinforcing portion 21. This causes the reinforcing portion 21 to break along the planned division line 13. In other words, the cutting groove 11c functions as a starting point for dividing the reinforcing portion 21, and the annular reinforcing portion 21 is divided into a plurality of chips along the planned division line 13.

[0066] Fig. 8 is a perspective view showing the wafer 11 in which the reinforcing portion 21 is divided into a plurality of chips 29. As shown in Fig. 8, among the plurality of chips 29 formed by dividing the reinforcing portion 21, the chip 29 supported by the convex portion 38 (see Fig. 6 and the like) of the chuck table 32 is arranged so as to protrude upward more than the other chips 29 and the device chip 27.

[0067] In the dividing step, the reinforcing portion 21 does not necessarily need to be divided along all of the cut grooves 11c. Specifically, it is sufficient that the reinforcing portion 21 is divided into a plurality of chips of a predetermined size or less so that the reinforcing portion 21 can be appropriately removed in the removing step described later.

[0068] 6, an example has been described in which the unevenness of the chuck table 32 is formed by the upper surface 34a of the frame body 34 and the protrusions 38, but there is no limitation on the method for forming the unevenness. For example, the unevenness may be formed by providing a plurality of recesses (grooves) on the upper surface 34a side of the frame body 34.

[0069] Furthermore, the method of applying an external force to the reinforcing portion 21 is not limited to suction of the adhesive tape 23 by the chuck table 32. For example, with the wafer 11 held by a predetermined chuck table, an external force may be applied to the reinforcing portion 21 by pressing a pressing member against the reinforcing portion 21. Alternatively, an external force may be applied to the reinforcing portion 21 by using a tape that can be expanded by application of an external force (expandable tape) as the adhesive tape 23, and the expandable tape may be pulled to expand the reinforcing portion 21.

[0070] Next, the reinforcing portion 21 divided into the plurality of chips 29 is removed (removal step). In the removal step, the plurality of chips 29 formed by dividing the reinforcing portion 21 are peeled off from the adhesive tape 23 and removed.

[0071] 9 is a perspective view showing the wafer 11 in the removal step. For example, around the wafer 11 held by the chuck table 32 (see FIG. 6 etc.), a nozzle 46 for spraying a fluid 48 and a recovery mechanism 50 for recovering the reinforcing portion 21 (chip 29) are installed.

[0072] The nozzle 46 is fixed at a predetermined injection position located radially outward of the outer periphery of the wafer 11. A fluid supply source (not shown) that supplies a fluid 48 to the nozzle 46 is connected to the nozzle 46. The nozzle 46 also has an injection port 46a that injects the fluid 48 supplied from the fluid supply source. There is no limitation on the fluid 48 injected from the nozzle 46, and a gas such as air is used. The fluid 48 may also be a liquid (high pressure liquid) such as pressurized pure water, or a mixed fluid containing a liquid (pure water, etc.) and a gas (air, etc.).

[0073] For example, the nozzle 46 is installed at approximately the same height as the wafer 11 so that the ejection port 46a faces the outer periphery (reinforcement portion 21) of the wafer 11. The direction of the nozzle 46 is adjusted so that the ejection port 46a intersects with a tangent to the outer periphery of the wafer 11. This causes the fluid 48 to be ejected along the tangent direction of the outer periphery of the wafer 11.

[0074] As the recovery mechanism 50, for example, a container having an opening 50a that opens toward the ejection port 46a side of the nozzle 46 is used. The nozzle 46 and the recovery mechanism 50 are arranged to sandwich the reinforcing portion 21 of the wafer 11. For example, the nozzle 46 and the recovery mechanism 50 are positioned on a tangent to the outer periphery of the wafer 11. As a result, the reinforcing portion 21 is arranged between the ejection port 46a of the nozzle 46 and the opening 50a of the recovery mechanism 50.

[0075] In the removal step, fluid 48 is sprayed from nozzle 46 while chuck table 32 (see FIG. 6, etc.) holding wafer 11 is rotated at a low speed (for example, 5 to 10 rpm). As a result, fluid 48 is sprayed toward reinforcing portion 21 from a spraying position (position of nozzle 46) located outside wafer 11. As a result, pressure is applied to reinforcing portion 21 by fluid 48, and divided reinforcing portion 21 (chips 29) are peeled off from adhesive tape 23. Then, divided reinforcing portion 21 (chips 29) are scattered in the opposite direction to the spraying position of fluid 48.

[0076] When the wafer 11 rotates once while the fluid 48 is being sprayed from the nozzle 46, the fluid 48 is sprayed over the entire area of ​​the reinforcing portion 21, and all the chips 29 are peeled off from the adhesive tape 23. As a result, the reinforcing portion 21 is removed, and only the device chips 27 remain on the adhesive tape 23.

[0077] In this manner, in this embodiment, since the annular reinforcing portion 21 is divided into a plurality of chips 29 in the dividing step, the reinforcing portion 21 can be easily removed in the removing step by simply applying an appropriate external force to each chip 29. This eliminates the need to prepare and operate a precise transport mechanism for transporting the reinforcing portion 21 in an annular state, and simplifies the work of removing the reinforcing portion 21.

[0078] 9, when the ejection position of the fluid 48 (the position of the nozzle 46) is set outside the wafer 11, the chips 29 scatter in one direction from the wafer 11. This makes it possible to prevent the chips 29 from scattering in random directions from the wafer 11, and makes it easier to collect the chips 29.

[0079] Furthermore, by disposing the recovery mechanism 50 so as to face the nozzle 46, the chips 29 scattered by the ejection of the fluid 48 are guided to the opening 50a of the recovery mechanism 50 and enter the recovery mechanism 50. That is, the chips 29 are removed and recovered at the same time. This eliminates the need to recover the scattered chips 29 after the removal step, improving work efficiency.

[0080] There is no limitation on the type of the recovery mechanism 50. For example, the recovery mechanism 50 may be a duct connected to a suction source such as an ejector. In this case, the scattered chips 29 can be reliably guided to the duct by injecting the fluid 48 from the nozzle 46 and applying the suction force (negative pressure) of the suction source to the duct.

[0081] As described above, in the wafer processing method according to this embodiment, the device region 17a is divided into a plurality of device chips 27 in the cutting step, and the cut grooves 11c are formed in the reinforcing portion 21. Then, in the dividing step, an external force is applied to the reinforcing portion 21, and the reinforcing portion 21 is divided starting from the cut grooves 11c. This makes it possible to easily remove the reinforcing portion 21 from the wafer 11 by the simple method of spraying the fluid 48 onto the divided reinforcing portion 21.

[0082] Furthermore, in the wafer processing method according to this embodiment, fluid 48 is sprayed toward reinforcing portion 21 from a predetermined spray position located on the outside of wafer 11, thereby scattering divided reinforcing portion 21 (multiple chips 29) toward the opposite side to the spray position. This makes it possible to prevent chips 29 from scattering in random directions from wafer 11, and makes it easy to collect chips 29.

[0083] In the removal step, the reinforcing portion 21 may be removed by alternately spraying the fluid 48 and rotating the chuck table 32. Specifically, first, the fluid 48 is sprayed onto a part of the reinforcing portion 21 while the chuck table 32 is stopped. Then, the chuck table 32 is rotated by a predetermined angle, and the fluid 48 is sprayed onto the part of the reinforcing portion 21 again. By repeating this operation until the wafer 11 has made one rotation, all the chips 29 are peeled off from the adhesive tape 23.

[0084] In the removal step, the device chips 27 may be covered with a protective film. For example, pure water may be supplied from above the chuck table 32 toward the wafer 11 to cover the device chips 27 with a water film. This makes it difficult for the device chips 27 to be damaged even if the chips 29 are scattered toward the device chips 27.

[0085] In addition, in this embodiment, an example has been described in which the dividing process and the removing process are performed using the same chuck table 32 (see FIG. 6, etc.), but the wafer 11 may be held by separate chuck tables for the dividing process and the removing process.

[0086] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0087] 11 Wafers 11a surface 11b Back side 11c cutting groove 13. Planned division line (street) 15 Devices 17a Device Area 17b Surplus outer area 19 Groove 19a Bottom 19b Side (inner wall) 21 Reinforcement part (convex part) 23 Adhesive Tape 25 Frames 25a opening 27 Device Chip 29 Chips 2 Cutting equipment 4 Chuck table (holding table) 4a Holding surface 6 Frame (main body) 6a Top side 6b Recess (groove) 8 Retaining member 8a Top 10 Clamp 12 Cutting unit 14 Housing 16 Cutting blade 18 Blade Cover 20 Connection 22 Nozzle 30 External Force Imparting Unit 32 Chuck table (holding table) 34 Frame (main body) 34a Top 34b Recess (groove) 36 Retaining member 36a Suction surface 38 Convex part (protrusion) 40a,40b,40c groove 42a, 42b Valve 44 Suction source 46 Nozzles 46a injection port 48 Fluid 50 Collection Mechanism 50a opening

Claims

1. A wafer processing method for processing a wafer having a surface side with device regions in which devices are formed in multiple regions partitioned by a plurality of planned division lines arranged in a lattice pattern so as to intersect with each other, a back side with recesses formed in regions corresponding to the device regions, and an annular reinforcing portion on an outer periphery surrounding the device regions and the recesses, comprising: a tape application step of applying an adhesive tape to the back surface side of the wafer along the recess and the reinforcing portion; a holding step of holding a bottom surface of the recessed portion via the adhesive tape by a first chuck table; a cutting step of cutting the wafer along the division lines with a cutting blade to divide the device region into a plurality of device chips and form cutting grooves in the reinforcing portion; a dividing step of dividing the reinforcement portion from the cut groove by applying an external force to the reinforcement portion; a removing step of spraying a fluid from a predetermined spray position located outside the wafer toward the reinforcing portion to scatter the divided reinforcing portion toward an opposite side to the spray position, The method for processing a wafer is characterized in that in the removing step, the fluid is sprayed along a tangential direction of the outer periphery of the wafer.

2. A wafer processing method for processing a wafer having a surface side with device regions in which devices are formed in multiple regions partitioned by a plurality of planned division lines arranged in a lattice pattern so as to intersect with each other, a back side with recesses formed in regions corresponding to the device regions, and an annular reinforcing portion on an outer periphery surrounding the device regions and the recesses, comprising: a tape application step of applying an adhesive tape to the back surface side of the wafer along the recess and the reinforcing portion; a holding step of holding a bottom surface of the recessed portion via the adhesive tape by a first chuck table; a cutting step of cutting the wafer along the division lines with a cutting blade to divide the device region into a plurality of device chips and form cutting grooves in the reinforcing portion; a dividing step of dividing the reinforcement portion from the cut groove by applying an external force to the reinforcement portion; a removing step of spraying a fluid from a predetermined spray position located outside the wafer toward the reinforcing portion to scatter the divided reinforcing portion toward an opposite side to the spray position, The removal process is a wafer processing method characterized in that a nozzle and a recovery mechanism are arranged to sandwich the reinforcing portion of the wafer, and the fluid is sprayed from the nozzle toward the reinforcing portion, causing the divided reinforcing portion to scatter toward the recovery mechanism and be recovered by the recovery mechanism.

3. 3. The wafer processing method according to claim 1 or 2, characterized in that in the dividing step, while the wafer is supported by a second chuck table having an unevenness at a position corresponding to the reinforcing portion of the wafer, the adhesive tape is sucked by the second chuck table, thereby arranging the adhesive tape along the unevenness to divide the reinforcing portion.

Images