JP7628368B2 - Wafer Processing Method - Google Patents

Description

The present invention relates to a wafer processing method.

In the device chip manufacturing process, a wafer is used that has a surface on which a device region is formed, with devices formed in each of multiple regions partitioned by multiple planned division lines (streets) arranged in a grid pattern. By dividing this wafer along the planned division lines, multiple device chips, each equipped with a device, are obtained. The device chips are mounted on various electronic devices such as mobile phones and personal computers.

In recent years, with the miniaturization of electronic devices, there is a demand for thinner device chips. Therefore, a process of thinning the wafer is sometimes carried out using a grinding device before dividing the wafer. The grinding device is equipped with a chuck table that holds the workpiece and a grinding unit that grinds the workpiece, and a grinding wheel having a grinding stone is attached to the grinding unit. 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 grinding wheel, thereby grinding and thinning the wafer.

However, when a wafer is thinned by grinding, the rigidity of the wafer decreases, making the wafer 11 more susceptible to deformation and breakage, and making it difficult to handle (transport, hold, etc.). 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. When this method is used, a recess is formed in the center of the back side of the wafer, while the outer periphery of the wafer is not thinned and remains thick, remaining as an annular reinforcing part. This prevents the rigidity of the wafer from decreasing after grinding.

The thinned wafer is finally divided into multiple device chips using a cutting device 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 1 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 protrusion), and then the reinforcing portion is lifted and removed by a claw assembly equipped with multiple claws.

JP 2011-61137 A

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

Therefore, in order to properly remove the reinforcing portion, it is necessary to hold the reinforcing portion carefully so that it does not interfere with the device area, and to lift the reinforcing portion without causing shaking or misalignment. As a result, the structure of the mechanism (claw assembly, etc.) used to remove the reinforcing portion becomes complicated, increasing costs. In addition, the work time required to remove the reinforcing portion becomes longer, reducing the operating efficiency of the processing device.

The present invention was made in consideration of these problems, and aims to provide a wafer processing method that can easily remove the reinforcing portion remaining on the outer periphery of the wafer.

According to one aspect of the present invention, a wafer processing method is provided for processing a wafer having a device region on the front side, 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 recess formed in a region corresponding to the device region on the back side, and an annular reinforcing portion surrounding the device region and the recess on the outer periphery, the method comprising the steps of: a tape application step of applying an adhesive tape having an adhesive layer that is cured by irradiation with ultraviolet light to the back side of the wafer along the recess and the reinforcing portion; a holding step of holding the bottom surface of the recess via the adhesive tape by a first chuck table; and a cutting blade. The wafer processing method includes a cutting step in which the device region is divided into a plurality of device chips by cutting the wafer along the planned division line and a groove is formed on the surface side of the reinforcing portion; an adhesive layer hardening step in which, before, during, or after the cutting step, ultraviolet light is applied to the annular region of the adhesive tape attached to the reinforcing portion to harden the region of the adhesive layer that contacts the reinforcing portion; a dividing step in which an external force is applied to the reinforcing portion to divide the reinforcing portion along the planned division line starting from the groove; and a reinforcing portion removal step in which a fluid is sprayed onto the divided reinforcing portion to remove the reinforcing portion.

Preferably, in the tape application step, the center of the adhesive tape is applied to the wafer and the outer periphery of the adhesive tape is applied to the annular frame, and in the adhesive layer hardening step, the ultraviolet light is also applied to the area of the adhesive tape that is not applied to the wafer and the frame, so that the area of the adhesive layer that is not in contact with the wafer and the frame is also hardened. Also, preferably, in the adhesive layer hardening step, the ultraviolet light is applied to the adhesive layer while the area of the adhesive layer that is not in contact with the wafer and the frame is in contact with a liquid.

Also, preferably, the fluid is a cleaning liquid supplied from a cleaning unit that cleans the wafer. Also, preferably, the fluid is sprayed from the center side toward the outer periphery side of the wafer. Also, preferably, the fluid is a mixed fluid containing gas and liquid.

In addition, preferably, in the dividing step, the wafer is supported by a second chuck table having an uneven surface 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 positioned along the uneven surface to divide the reinforcing portion.

In addition, preferably, the wafer processing method further includes a separation step of separating the device region and the reinforcing portion by cutting the outer periphery of the device region in an annular shape with the cutting blade after the holding step and before the dividing step.

In addition, preferably, the wafer processing method further includes a scribe line forming step, which is performed after the cutting step and before the dividing step, of forming a plurality of scribe lines in the reinforcing portion along the radial direction of the reinforcing portion.

In a wafer processing method according to one aspect of the present invention, in a cutting step, the device region is divided into a plurality of device chips, and a groove is formed on the surface side of the 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 groove. As a result, it is possible to remove the reinforcing portion from the wafer by a simple method of spraying a fluid onto the divided reinforcing portion.

In addition, in a wafer processing method according to one aspect of the present invention, after the adhesive strength of the adhesive layer of the adhesive tape is reduced in the adhesive layer hardening step, a fluid is sprayed onto the divided reinforcing portion in the reinforcing portion removal step. This allows the reinforcing portion to be easily removed from the adhesive tape.

FIG. 1A is a perspective view showing the front side of a wafer, and FIG. 1B is a perspective view showing the back side of the wafer. FIG. 2(A) is a perspective view showing a wafer to which an adhesive tape has been adhered, FIG. 2(B) is a cross-sectional view showing the wafer to which an adhesive tape has been adhered, and FIG. 2(C) is a cross-sectional view showing a portion of the adhesive tape. FIG. 4 is a cross-sectional view showing a wafer held by a first chuck table. FIG. FIG. 5A is a cross-sectional view showing a wafer cut along a first direction, and FIG. 5B is a cross-sectional view showing a wafer cut along a second direction. FIG. 6A is a cross-sectional view showing the wafer in the adhesive layer hardening step, and FIG. 6B is an enlarged cross-sectional view showing the reinforcing portion of the wafer in the adhesive layer hardening step. FIG. FIG. 8A is a cross-sectional view showing a wafer placed on the second chuck table, and FIG. 8B is a cross-sectional view showing the wafer sucked by the second chuck table. FIG. 13 is a perspective view showing a wafer in which a reinforcing portion is divided into a plurality of chips. FIG. 10A is a cross-sectional view showing a wafer in which a fluid is injected onto a reinforcing portion, and FIG. 10B is a cross-sectional view showing a wafer in which the reinforcing portion has been removed. FIG. 11(A) is a plan view showing a cutting device equipped with a groove forming unit, and FIG. 11(B) is a cross-sectional view showing a cutting device equipped with a groove forming unit.

An embodiment of the present invention will now be described with reference to the accompanying drawings. First, an example of the structure of a wafer that can be processed using the 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.

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 divided into a plurality of rectangular regions by a plurality of planned division lines (streets) 13 arranged in a grid 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) devices are formed on the front surface 11a side of each of the regions divided by the planned division lines 13.

The wafer 11 has, on the surface 11a side, a substantially circular device region 17A in which multiple 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) that includes the outer periphery of the 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.

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. Furthermore, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 15.

By dividing the wafer 11 into a grid pattern along the planned division lines 13, multiple device chips, each of which includes a device 15, are manufactured. In addition, by performing a thinning process on the wafer 11 before division, it is possible to obtain thinned device chips.

A grinding device, for example, is used to thin the wafer 11. The grinding device is equipped with a chuck table (holding table) that holds the workpiece and a grinding unit that grinds the workpiece, and an annular grinding wheel with a grinding stone is attached to the grinding unit. The wafer 11 is held by the chuck table, and when the grinding stone is brought into contact with the back surface 11b of the wafer 11 while the chuck table and grinding wheel are rotated, the wafer 11 is ground and thinned.

However, if the entire back surface 11b side of the wafer 11 is ground, the entire wafer 11 is thinned and the rigidity of the wafer 11 is reduced. This makes the wafer 11 more susceptible to deformation or damage, and makes handling (transporting, holding, etc.) of the wafer 11 difficult. For this reason, the thinning process (grinding) is sometimes performed only on the center of the back surface 11b side of the wafer 11.

For example, as shown in FIG. 1(B), only the central portion of the wafer 11 is thinned, and a cylindrical 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 roughly the same as the size (diameter) of the device region 17A, and the recess 19 is formed at a position overlapping the device region 17A.

The recess 19 includes a bottom surface 19a that is generally parallel to the front surface 11a and 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 back surface 11b and bottom surface 19a. A reinforcing portion (protruding portion) 21 remains on the outer periphery of the wafer 11, which corresponds to an area that has not been subjected to the thinning process (grinding process). The reinforcing portion 21 includes the outer periphery excess region 17B, and surrounds the device region 17A and the recess 19.

When only the central portion of the wafer 11 is thinned, the outer periphery of the wafer 11 (reinforcement portion 21) remains thick. This prevents the rigidity of the wafer 11 from decreasing, making the wafer 11 less susceptible to damage. In other words, the reinforcement portion 21 functions as a reinforcing region that reinforces the wafer 11.

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

An adhesive tape 23 large enough to cover 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 with a diameter larger than the wafer 11 is attached so as to cover the back surface 11b of the wafer 11.

The adhesive tape 23 is applied along the contour of the back surface 11b of the wafer 11. That is, as shown in FIG. 2(B), the adhesive tape 23 is applied along (following) the bottom surface 19a and side surface 19b of the recess 19 and the back surface (lower surface) of the reinforcing portion 21. Note that FIG. 2(B) shows an example in which the adhesive tape 23 is applied so as to be in close contact with the bottom surface 19a and side surface 19b, but 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.

Figure 2 (C) is a cross-sectional view showing a portion of the adhesive tape 23. The adhesive tape 23 is a flexible sheet that includes a circular base material 25 and an adhesive layer (glue layer) 27 provided on the base material 25.

For example, the base material 25 is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer 27 has the property of being hardened by irradiation with ultraviolet light. Specifically, an adhesive made of an ultraviolet-curing resin is used for the adhesive layer 27. When the adhesive layer 27 is irradiated with ultraviolet light, the adhesive layer 27 hardens and the adhesive strength of the adhesive layer 27 decreases.

As shown in Figures 2(A) and 2(B), the outer periphery of the adhesive tape 23 is not attached to the wafer 11, but is attached to an annular frame 29 made of a metal such as SUS (stainless steel). A cylindrical opening 29a is provided in the center of the frame 29, penetrating the frame 29 in the thickness direction. The diameter of the opening 29a is larger than the diameter of the wafer 11. The wafer 11 is placed inside the opening 29a.

The adhesive tape 23 is attached to the wafer 11 and the frame 29 so that the adhesive layer 27 (see FIG. 2(C)) contacts the bottom surface 19a and side surface 19b of the recess 19, the lower surface of the reinforcing portion 21, and the lower surface side of the frame 29. That is, the center of the adhesive tape 23 is attached to the rear surface 11b side of the wafer 11, and the outer periphery of the adhesive tape 23 is attached to the frame 29. As a result, the wafer 11 is supported by the frame 29 via the adhesive tape 23. The upper surface side of the adhesive tape 23 (adhesive layer 27) is exposed between the wafer 11 and the frame 29.

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. The cutting device 2 includes a first chuck table (first holding table) 4 that holds the wafer 11, and a cutting unit 12 that cuts the wafer 11 held by the first chuck table 4. 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 mutually perpendicular. The Z-axis direction (height direction, vertical direction, up-down direction) is perpendicular to the X-axis direction and the Y-axis direction.

The upper surface of the first chuck table 4 is a flat surface that is roughly parallel to the horizontal direction (XY plane direction) and forms a circular holding surface 4a (see FIG. 4) that holds the wafer 11. A ball screw type moving mechanism (not shown) that moves the first chuck table 4 along the X-axis direction is connected to the first chuck table 4. Furthermore, a rotational drive source (not shown) such as a motor that rotates the first chuck table 4 around a rotation axis roughly parallel to the Z-axis direction is connected to the first chuck table 4.

A cutting unit 12 is disposed above the first chuck table 4. The cutting unit 12 includes a cylindrical housing 14. The housing 14 accommodates a cylindrical spindle (not shown) disposed along the Y-axis direction. The tip (one end) of the spindle is exposed to the outside of the housing 14, and a rotational drive source such as a motor is connected to the base (other end) of the spindle.

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

As the cutting blade 16, for example, a hub-type cutting blade (hub blade) is used. The hub blade is composed of an annular base made of metal or the like, and an annular cutting edge formed along the outer periphery of the base. The cutting edge of the hub blade is composed of an electroformed grinding stone containing abrasive grains made of diamond or the like and a binder such as a nickel-plated layer that fixes the abrasive grains.

However, a washer-type cutting blade (washer blade) can also be used as the cutting blade 16. A washer blade is composed of an annular cutting edge that contains abrasive grains and a binder made of metal, ceramics, resin, etc. that fixes the abrasive grains in place.

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 has a pair of connectors 20 that are connected to a tube (not shown) through which a liquid (cutting fluid) such as pure water is supplied.

The blade cover 18 also includes a pair of nozzles 22 connected to a pair of connectors 20. The pair of nozzles 22 are arranged on both sides (front and back sides) of the cutting blade 16 so as to sandwich the lower end of the cutting blade 16. Each of the pair of nozzles 22 also has a supply port (not shown) that opens toward the cutting blade 16.

When cutting fluid is supplied to the pair of connection parts 20, the cutting fluid flows into the pair of nozzles 22 and is sprayed from the supply port toward both sides of the cutting blade 16. This cutting fluid cools the wafer 11 and the cutting blade 16, and also washes away debris (cutting debris) that is generated when the wafer 11 is cut by the cutting blade 16.

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

When processing the wafer 11 using the cutting device 2, the wafer 11 is first held by the first chuck table 4 (holding step). Figure 4 is a cross-sectional view showing the wafer 11 held by the first chuck table 4.

The first chuck table 4 has a cylindrical frame (main body) 6 made of metal, glass, ceramics, resin, or the like. A cylindrical recess (groove) 6b is provided on the upper surface 6a side of the frame 6. The diameter of the recess 6b is smaller than the diameter of the upper surface 6a, and the recess 6b is formed concentrically with the upper surface 6a.

A disk-shaped holding member 8 is fitted into the recess 6b. The holding member 8 is made of a porous material such as porous ceramics, and contains holes (suction paths) inside that connect the upper surface to the lower surface of the holding member 8. The holding member 8 is connected to a suction source (not shown) such as an ejector via a flow path (not shown) and a valve (not shown) formed inside the frame 6.

The upper surface of the holding member 8 forms a circular suction surface 8a that sucks the wafer 11. The upper surface 6a of the frame 6 and the suction surface 8a of the holding member 8 are disposed on approximately the same plane, forming the holding surface 4a of the first chuck table 4.

The wafer 11 is placed on the first chuck table 4 so that the surface 11a side is exposed upward. The first 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 first 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.

In addition, a number of clamps 10 that grip and secure the frame 29 are provided around the first chuck table 4. When the wafer 11 is placed on the first chuck table 4, the frame 29 is secured by the clamps 10.

When the suction force (negative pressure) of the suction source is applied to the suction surface 8a of the holding member 8 while the wafer 11 is placed on the first chuck table 4, the area of the adhesive tape 23 that is attached to the bottom surface 19a of the recess 19 is sucked by the suction surface 8a. As a result, the bottom surface 19a of the recess 19 is sucked and held by the first chuck table 4 via the adhesive tape 23.

Next, the wafer 11 is cut along the planned 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 planned dividing lines 13 parallel to the first direction and along the planned dividing lines 13 parallel to the second direction that intersects with the first direction.

Figure 5 (A) is a cross-sectional view showing a wafer 11 being cut along a first direction. First, the first chuck table 4 is rotated to align the length direction of one planned division line 13, which is 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 one planned division line 13.

The height of the cutting unit 12 is then adjusted so that the lower end of the cutting blade 16 is positioned below the bottom surface 19a of the recess 19. Specifically, 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.

Then, while rotating the cutting blade 16, the first chuck table 4 is moved along the X-axis direction. As a result, the first 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.

The cutting depth of the cutting blade 16 is greater than the thickness of the central portion (device region 17A) of the wafer 11, and less than the thickness of the peripheral portion (reinforcement portion 21) of the wafer 11. Therefore, in the device region 17A of the wafer 11, a cut (kerf) is formed along one planned division line 13, extending from the front surface 11a to the bottom surface 19a. Meanwhile, in the reinforcement portion 21 of the wafer 11, a groove 11c of a depth corresponding to the cutting depth of the cutting blade 16 is formed along one planned division line 13.

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

Next, the first chuck table 4 is rotated 90° to align the length direction of the planned dividing line 13 parallel to the second direction with the X-axis direction. Then, by following a similar procedure, the wafer 11 is cut along the planned dividing line 13 parallel to the second direction. Figure 5 (B) is a cross-sectional view showing the wafer 11 being cut along the second direction.

When the wafer 11 is cut along all of the planned division lines 13, the device region 17A of the wafer 11 is divided along the planned division lines 13 to form a plurality of device chips 31 (see FIG. 6(A) etc.), each of which includes a device 15. In addition, a groove 11c is formed along the planned division lines 13 on the upper surface side (surface 11a side) of the reinforcing portion 21.

Next, the adhesive tape 23 is irradiated with ultraviolet light to harden the adhesive layer 27 (adhesive layer hardening step). Figure 6 (A) is a cross-sectional view showing the wafer 11 in the adhesive layer hardening step.

The cutting device 2 (see FIG. 3) is equipped with an ultraviolet irradiation unit 24 that irradiates ultraviolet light 26. The ultraviolet irradiation unit 24 is installed below the holding surface 4a of the first chuck table 4 and the clamp 10. For example, an ultraviolet lamp is used as the ultraviolet irradiation unit 24.

The position of the ultraviolet irradiation unit 24 in the horizontal direction (XY plane direction) is adjusted so that the ultraviolet irradiation unit 24 overlaps the area between the holding surface 4a of the first chuck table 4 and the clamp 10. Therefore, when the wafer 11 is held by the first chuck table 4, the area of the adhesive tape 23 that is attached to the reinforcing portion 21 is positioned directly above the ultraviolet irradiation unit 24.

In the adhesive layer hardening step, the first chuck table 4 is rotated while the ultraviolet irradiation unit 24 irradiates the adhesive tape 23 with ultraviolet light 26. This causes the ultraviolet light 26 to be irradiated from the underside (back surface 11b side) of the wafer 11 onto the annular area of the adhesive tape 23 that is attached to the reinforcing portion 21.

Figure 6 (B) is an enlarged cross-sectional view showing the reinforcing portion 21 of the wafer 11 in the adhesive layer hardening step. When ultraviolet light 26 is irradiated to the area of the adhesive tape 23 that is attached to the reinforcing portion 21, the area of the adhesive layer 27 that is in contact with the reinforcing portion 21 hardens. As a result, the adhesive strength of the area of the adhesive layer 27 that is in contact with the reinforcing portion 21 decreases. This makes it easier for the reinforcing portion 21 to be separated from the adhesive tape 23.

Also, as shown in FIG. 6(B), in the adhesive layer hardening step, ultraviolet light 26 may also be irradiated to the area of the adhesive tape 23 that is not attached to the wafer 11 and the frame 29 (the area between the wafer 11 and the frame 29). In this case, the area of the adhesive layer 27 that is in contact with the reinforcing portion 21 and the area that is not in contact with the wafer 11 and the frame 29 are hardened.

On the other hand, it is preferable that the area of the adhesive tape 23 that is attached to the bottom surface 19a of the recess 19 and the area that is attached to the frame 29 are not irradiated with ultraviolet light 26. This maintains the adhesive strength between the area of the adhesive layer 27 that is in contact with the bottom surface 19a of the recess 19 and the area that is in contact with the frame 29. As a result, the adhesive tape 23 remains firmly attached to the device chip 31 and the frame 29.

For example, when the adhesive tape 23 is attached to the wafer 11, air may get between the reinforcing portion 21 and the adhesive tape 23, and the oxygen contained in the air may remain between the reinforcing portion 21 and the adhesive layer 27. If the adhesive tape 23 is irradiated with ultraviolet light 26 in this state, the polymerization of the adhesive layer 27 made of ultraviolet curable resin may be inhibited by the oxygen (polymerization inhibition), and the adhesive layer 27 may become difficult to cure.

Therefore, when irradiating the adhesive tape 23 with ultraviolet light, it is preferable to supply liquid 28 such as pure water between the wafer 11 and the frame 29. For example, the nozzle 22 (see FIG. 3) of the cutting unit 12 is positioned directly above the gap between the wafer 11 and the frame 29, and cutting fluid is dripped from the nozzle 22 between the wafer 11 and the frame 29. This causes the liquid 28 to be stored between the wafer 11 and the frame 29, and the liquid 28 comes into contact with the adhesive layer 27 exposed between the wafer 11 and the frame 29.

However, there is no limitation on the method of supplying the liquid 28. For example, a supply nozzle that supplies the liquid 28 between the wafer 11 and the frame 29 may be provided on the outer periphery of the first chuck table 4. In this case, the liquid 28 can be supplied from the supply nozzle to the adhesive tape 23, and the process of adjusting the position of the nozzle 22 of the cutting unit 12 can be omitted.

The liquid 28 stored between the wafer 11 and the frame 29 penetrates into the gap between the reinforcing part 21 and the adhesive layer 27. As a result, the air (oxygen) present in the gap between the reinforcing part 21 and the adhesive layer 27 becomes bubbles and moves to the liquid surface of the liquid 28. This removes oxygen from the gap between the reinforcing part 21 and the adhesive layer 27, preventing polymerization inhibition of the adhesive layer 27.

The adhesive layer hardening step may be performed at any time, as long as it is performed before the reinforcing portion removal step described below. For example, the adhesive layer hardening step may be performed before the cutting step. Specifically, before the cutting blade 16 cuts the wafer 11 (see Figures 5(A) and 5(B)), liquid 28 (cutting fluid) is supplied between the wafer 11 and the frame 29 from the nozzle 22 (see Figure 3) of the cutting unit 12. Then, ultraviolet light 26 is irradiated onto the adhesive tape 23 from the ultraviolet light irradiation unit 24.

The adhesive layer hardening step can also be performed during the cutting step. For example, after cutting the wafer 11 along the first direction (see FIG. 5(A)), the adhesive tape 23 can be irradiated with ultraviolet light 26, and then the wafer 11 can be cut along the second direction (see FIG. 5(B)). In this case, the cutting fluid (liquid 28) supplied to the wafer 11 when cutting the wafer 11 along the first direction flows into and is stored between the wafer 11 and the frame 29.

Furthermore, in the adhesive layer hardening step, ultraviolet rays may be irradiated onto the adhesive tape 23 using a device other than the cutting device 2. For example, an ultraviolet irradiating device equipped with a chuck table and an ultraviolet irradiating unit may be used. The ultraviolet irradiating device may also be equipped with a supply nozzle that supplies liquid 28 to the adhesive layer 27 exposed between the wafer 11 and the frame 29.

Next, an external force is applied to the reinforcing portion 21, so that the reinforcing portion 21 is divided along the planned division line 13 starting from the groove 11c (division step). In this embodiment, an external force is applied to the reinforcing portion 21 by sucking the adhesive tape 23 with the second chuck table.

Figure 7 is a perspective view showing the cleaning unit 30. The cleaning unit 30 is a mechanism for cleaning the wafer 11 after cutting, and is mounted on the cutting device 2 (see Figure 3). The cleaning unit 30 includes a second chuck table (second holding table) 32 that holds the wafer 11, and a fluid supply unit 46 that supplies a cleaning fluid to the wafer 11 held by the second chuck table 32.

The upper surface of the second chuck table 32 forms a circular holding surface that holds the wafer 11. In addition, a rotational drive source such as a motor (not shown) that rotates the second chuck table 32 around a rotation axis that is roughly parallel to the vertical direction is connected to the second chuck table 32. The wafer 11 is held by the second chuck table 32, and the fluid supply unit 46 supplies a cleaning liquid such as pure water to the wafer 11 while rotating the second chuck table 32, thereby cleaning the wafer 11.

The second chuck table 32 has a cylindrical frame (main body) 34 made of metal, glass, ceramics, resin, or the like. A cylindrical recess (groove) 34b is provided on the upper surface 34a side of the frame 34. The diameter of the recess 34b is smaller than the diameter of the upper surface 34a, and the recess 34b is formed concentrically with the upper surface 34a.

A disk-shaped holding member 36 is fitted into the recess 34b. The holding member 36 is made of a porous material such as porous ceramics, and contains holes (suction paths) inside that connect the upper surface to the lower surface of the holding member 36. The upper surface of the holding member 36 forms a circular suction surface 36a that holds the wafer 11 by suction. The upper surface 34a of the frame 34 and the suction surface 36a of the holding member 36 are arranged on approximately the same plane.

The second chuck table 32 has projections and recesses at positions corresponding to the outer periphery (reinforcement portion 21) of the wafer 11. For example, the frame 34 is formed so that the upper surface 34a overlaps with the reinforcement portion 21 when the wafer 11 is placed on the second chuck table 32. In addition, the upper surface 34a of the frame 34 has a plurality of projections (protrusions) 38 protruding upward from the upper surface 34a.

The multiple protrusions 38 are arranged at approximately equal intervals along the circumferential direction of the frame body 34. The upper surface 34a of the frame body 34 and the protrusions 38 form an annular region having periodic irregularities. Note that while FIG. 7 shows the protrusions 38 formed in a rectangular parallelepiped shape, there is no limitation on the shape of the protrusions 38.

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

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. The suction source 44 is composed of an ejector or the like.

In the division step, the wafer 11 is placed on the second chuck table 32 so that the reinforcing portion 21 overlaps the upper surface 34a of the frame 34. This causes the reinforcing portion 21 of the wafer 11 to be supported by the multiple protrusions 38 via the adhesive tape 23.

Figure 8 (A) is a cross-sectional view showing the wafer 11 placed on the second chuck table 32. For ease of explanation, Figure 8 (A) only shows the cross-sectional shapes of the wafer 11, adhesive tape 23, frame 29, and second chuck table 32. When the valves 42a and 42b are opened with the wafer 11 placed on the second chuck table 32, the negative pressure of the suction source 44 acts on the holding member 36 and grooves 40a and 40b, and the wafer 11 and adhesive tape 23 are sucked onto the second chuck table 32.

Figure 8 (B) is a cross-sectional view showing the wafer 11 sucked by the second chuck table 32. The area of the adhesive tape 23 attached to the inside of the recess 19 of the wafer 11 is sucked by the holding member 36, peeled off from the recess 19, and contacts the suction surface 36a. The area of the adhesive tape 23 attached to the reinforcing part 21 is sucked by the grooves 40a and 40b, peeled off from the reinforcing part 21, and contacts the upper surface 34a of the frame 34.

As shown in FIG. 7, the upper surface 34a of the frame 34 has a plurality of protrusions 38 that form periodic irregularities in a circular pattern. Therefore, when negative pressure is applied to the grooves 40a and 40b, the area of the adhesive tape 23 that is attached to the reinforcing portion 21 is deformed along the upper surface 34a of the frame 34 and the protrusions 38, and becomes wavy. The area of the reinforcing portion 21 that is not supported by the protrusions 38 is pulled toward the upper surface 34a of the frame 34 by the adhesive tape 23, and moves between the adjacent protrusions 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 with the second chuck table 32.

When an external force is applied to the reinforcing portion 21, a crack occurs from the groove 11c (see FIG. 7, etc.) 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 groove 11c functions as the starting point for dividing the reinforcing portion 21, and the annular reinforcing portion 21 is divided into multiple chips along the planned division line 13.

Figure 9 is a perspective view showing a wafer 11 in which the reinforcing portion 21 is divided into a plurality of chips 33. As shown in Figure 9, among the plurality of chips 33 formed by dividing the reinforcing portion 21, the chip 33 supported by the protrusion 38 (see Figure 7, etc.) of the second chuck table 32 is positioned so as to protrude above the device chip 31 and the other chips 33.

Note that in the dividing step, the reinforcing portion 21 does not necessarily have to be divided along all of the grooves 11c. In other words, it is sufficient that the reinforcing portion 21 is divided into multiple chips of a predetermined size or smaller so that the reinforcing portion 21 can be appropriately removed in the reinforcing portion removal step described below.

In addition, in FIG. 7, an example is described in which the unevenness of the second 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 of 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.

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 second chuck table 32. For example, an external force may be applied to the reinforcing portion 21 by pressing a pressing member against the reinforcing portion 21 while the wafer 11 is held by a predetermined chuck table. In addition, an external force may be applied to the reinforcing portion 21 by using a tape that can be expanded by the application of an external force (expandable tape) as the adhesive tape 23, and expanding the expandable tape by pulling it.

Next, the reinforcing portion 21, which has been divided into a plurality of chips 33, is removed by spraying a fluid onto the reinforcing portion 21 (reinforcing portion removal step). In the reinforcing portion removal step, each chip 33 formed by dividing the reinforcing portion 21 is peeled off and removed from the adhesive tape 23. This leaves only the plurality of device chips 31 attached to the adhesive tape 23.

To remove the reinforcing portion 21, for example, a fluid supply unit 46 (see FIG. 7) is used. The fluid supply unit 46 includes a nozzle 48 that sprays fluid and an arm 50 that rotates the nozzle 48.

Figure 10 (A) is a cross-sectional view showing the wafer 11 in which the fluid 52 is sprayed onto the reinforcing portion 21. In the reinforcing portion removal step, the nozzle 48 is first rotated and positioned so that it overlaps with the inner region of the reinforcing portion 21. Then, the fluid 52 is sprayed from the nozzle 48 toward the reinforcing portion 21. As a result, the chip 33 is blown away by the fluid 52 and peeled off from the adhesive tape 23, and is removed.

Figure 10 (B) is a cross-sectional view showing the wafer 11 from which the reinforcing portion 21 is removed. When removing the reinforcing portion 21 by spraying fluid 52, it is preferable to spray the fluid 52 from the center side of the wafer 11 (inside the reinforcing portion 21) toward the outer periphery side of the wafer 11 (outside the reinforcing portion 21). In this case, the chips 33 are scattered radially outward from the reinforcing portion 21. This makes it possible to prevent the chips 33 from scattering toward the device chip 31 and damaging the device chip 31. For example, the spray direction of the fluid 52 can be adjusted by tilting the nozzle 48 relative to the vertical direction (see Figures 10 (A) and 10 (B)).

Then, the second chuck table 32 is rotated while the fluid 52 is sprayed from the nozzle 48. This causes the fluid 52 to be sprayed over the entire reinforcing portion 21, and the chips 33 are sequentially peeled off and removed from the adhesive tape 23.

If the reinforcing portion 21 is not divided and remains in a continuous ring shape, in order to properly remove the reinforcing portion 21, it is necessary to hold the reinforcing portion 21 carefully and lift it up so as not to cause the reinforcing portion 21 to wobble or shift in position. This requires a precise transport mechanism or the like to remove the reinforcing portion 21, and the time required to remove the reinforcing portion 21 is also longer.

In contrast, in this embodiment, the annular reinforcing portion 21 is divided into a plurality of chips 33 in the dividing step. Therefore, in the reinforcing portion removing step, the reinforcing portion 21 can be easily removed by simply applying an appropriate external force to each chip 33.

In addition, in the adhesive layer hardening step described above (see FIG. 6(A) and FIG. 6(B)), the area of the adhesive layer 27 of the adhesive tape 23 that comes into contact with the reinforcing portion 21 is hardened, so that the adhesive strength of that area of the adhesive layer 27 is reduced. Therefore, when the fluid 52 is sprayed onto the reinforcing portion 21, the tip 33 is easily peeled off from the adhesive tape 23. This makes it extremely easy to remove the reinforcing portion 21.

Furthermore, if the areas of the adhesive layer 27 of the adhesive tape 23 that are not in contact with the wafer 11 and the frame 29 are also hardened in the adhesive layer hardening step described above (see Figures 6(A) and 6(B)), the adhesive strength of the areas of the adhesive layer 27 exposed between the wafer 11 and the frame 29 is also reduced. This makes it possible to prevent the chips 33 scattered by the spray of the fluid 52 from adhering again to the adhesive tape 23, and ensures that the chips 33 are removed from the adhesive tape 23.

There is no restriction on the fluid 52 sprayed onto the reinforcing portion 21. For example, a cleaning liquid for cleaning the wafer 11 can be used as the fluid 52. Specifically, a mixed fluid containing a gas such as air and a liquid such as pure water can be used as the fluid 52.

When spraying fluid onto the reinforcing portion 21, the device chips 31 may be covered with a protective film. For example, pure water may be supplied from above the second chuck table 32 toward the wafer 11, and the device chips 31 may be covered with a water film. This makes it difficult for the device chips 31 to be damaged even if the chips 33 are scattered toward the device chips 31. In this case, the cleaning unit 30 may be equipped with a nozzle that supplies a liquid (such as pure water) for forming a protective film to the wafer 11 held by the second chuck table 32.

In addition, although the above describes a case where the division step and the reinforcing part removal step are performed using the second chuck table 32 provided in the cleaning unit 30, it is also possible to use another chuck table prepared separately from the cleaning unit 30. In this case, a nozzle that sprays the fluid 52 toward the reinforcing part 21 is installed above the chuck table. Also, different chuck tables may be used for the division step and the reinforcing part removal step.

After the outer periphery (reinforcement portion 21) of the wafer 11 is removed, the area of the adhesive tape 23 that is attached to the bottom surface 19a of the recess 19 is irradiated with ultraviolet light as necessary to reduce the adhesive strength of the area of the adhesive layer 27 that is in contact with the bottom surface 19a of the recess 19. The device chip 31 is then picked up from the adhesive tape 23 and mounted, for example, on a specified mounting board.

As described above, in the wafer processing method according to this embodiment, in the cutting step, the device region 17A is divided into a plurality of device chips 31, and grooves 11c are formed on the surface side of 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 grooves 11c. As a result, it is possible to remove the reinforcing portion 21 from the wafer 11 by the simple method of spraying a fluid 52 onto the divided reinforcing portion 21.

In addition, in the above-mentioned wafer processing method, after the adhesive strength of the adhesive layer 27 of the adhesive tape 23 is reduced in the adhesive layer hardening step, the fluid 52 is sprayed onto the divided reinforcing portion 21 in the reinforcing portion removal step. This allows the reinforcing portion 21 to be easily removed from the adhesive tape 23.

In the above-mentioned wafer processing method, the device region 17A and the reinforcing portion 21 may be separated (separation step) after the holding step (see FIG. 4) and before the division step (see FIG. 8(A) and FIG. 8(B)). For example, the separation step is performed using the cutting device 2 shown in FIG. 3 before or after the cutting step (see FIG. 5(A) and FIG. 5(B)).

Specifically, first, with the wafer 11 held by the first chuck table 4 (see FIG. 4), the positions of the first chuck table 4 and the cutting unit 12 are adjusted so that the cutting blade 16 is positioned directly above the outer periphery of the device region 17A (thinned region) of the wafer 11. Then, the cutting unit 12 is lowered while rotating the cutting blade 16, causing the cutting blade 16 to cut into part of the outer periphery of the device region 17A. The amount of descent of the cutting unit 12 at this time is set so that the bottom end of the cutting blade 16 reaches the adhesive tape 23 attached to the bottom surface 19a of the recess 19.

Next, with the cutting blade 16 cutting into the wafer 11, the first chuck table 4 is rotated once while the cutting blade 16 is still rotating. This cuts and cuts the wafer 11 into a ring shape along the boundary between the device region 17A and the peripheral excess region 17B. As a result, the reinforcing portion 21 is cut off from the wafer 11, and the device region 17A and the reinforcing portion 21 are separated.

When the above separation step is performed, the protrusions (see Figures 8(A) and 8(B)) protruding from the top of the reinforcing portion 21 toward the device chip 31 do not remain or are shortened when the subsequent division step is performed. This makes it possible to prevent the protrusions pulled by the adhesive tape 23 from breaking and scattering toward the device chip 31 when the adhesive tape 23 is sucked in the division step.

In addition, in the above-mentioned wafer processing method, after the cutting step (see Figures 5(A) and 5(B)) and before the division step (see Figures 8(A) and 8(B)), multiple scribe lines (grooves) may be formed in the reinforcing portion 21 (scribe line formation step).

The scribe line formation step is performed, for example, by using a cutting device 2 equipped with a groove formation unit (scribe line formation unit) 60. FIG. 11(A) is a plan view showing the cutting device 2 equipped with the groove formation unit 60, and FIG. 11(B) is a cross-sectional view showing the cutting device 2 equipped with the groove formation unit 60. Note that FIG. 11(B) illustrates the wafer 11 after the cutting step has been performed.

For example, the groove forming unit 60 is attached to the side of the housing 14 of the cutting unit 12. Specifically, the groove forming unit 60 includes a fixing member 62 that is fixed to the side of the housing 14. The fixing member 62 is formed in an L-shape in a plan view, and is disposed adjacent to the housing 14 in the X-axis direction.

A cutter 64 that forms a scribe line (groove) in the wafer 11 and a pressing member 66 that presses the wafer 11 are fixed to the underside of the fixed member 62. The cutter 64 and the pressing member 66 are arranged adjacent to each other in the Y-axis direction.

The cutter 64 has a cutting blade 64a at its lower end. For example, a diamond cutter is used as the cutting blade 64a. The pressing member 66 is a cylindrical member made of metal, resin, or the like. The lower surface of the pressing member 66 is curved, forming a pressing surface 66a that presses the wafer 11.

In the scribe line forming step, first, the groove forming unit 60 is moved so that the cutting blade 64a of the cutter 64 comes into contact with the surface side of the reinforcement part 21. The movement of the groove forming unit 60 is controlled by a moving mechanism (not shown) connected to the cutting unit 12. Then, with the cutting blade 64a in contact with the reinforcement part 21, the groove forming unit 60 is moved along the Y-axis direction. As a result, a linear scribe line is formed on the surface side of the reinforcement part 21 along the radial direction of the reinforcement part 21.

Next, the first chuck table 4 is rotated a predetermined angle, and scribe lines are similarly formed on the reinforcing portion 21. By repeating this procedure, multiple scribe lines are formed along the radial direction of the reinforcing portion 21.

The scribe lines, together with the grooves 11c (see FIG. 7, etc.) formed in the reinforcing portion 21, function as the starting point for dividing the wafer 11. In other words, when the scribe lines are formed, cracks are more likely to occur in the reinforcing portion 21 during the division step (see FIG. 8(A) and FIG. 8(B)), and this assists in the division of the reinforcing portion 21. This ensures that the reinforcing portion 21 can be divided into multiple chips 33.

In addition, after forming a scribe line in the reinforcing portion 21, the pressing member 66 may be pressed against the reinforcing portion 21 to apply an external force to the reinforcing portion 21, thereby dividing the reinforcing portion 21. Specifically, after forming a scribe line in the reinforcing portion 21 with the cutter 64, the cutting unit 12 is moved along the Y-axis direction to position the pressing member 66 directly above the reinforcing portion 21.

Then, the cutting unit 12 is moved along the Z-axis direction, and the pressing member 66 is lowered toward the reinforcing portion 21. This causes the pressing surface 66a to come into contact with the reinforcing portion 21, pressing the reinforcing portion 21 downward. As a result, an external force is applied to the reinforcing portion 21, and the reinforcing portion 21 is divided starting from the groove 11c (see FIG. 7, etc.) or the scribe line.

Then, the first chuck table 4 is rotated by a predetermined angle, and the formation of the scribe line and the pressing of the reinforcing portion 21 by the pressing member 66 are repeated. In other words, the scribe line formation step and the division step are performed alternately multiple times. As a result, the reinforcing portion 21 is broken sequentially along the circumferential direction, and finally the reinforcing portion 21 is divided into multiple chips.

In addition, the structures, methods, etc. according to the above embodiments can be modified as appropriate without departing from the scope of the present invention.

11 Wafer 11a Front surface 11b Back surface 11c Groove 13 Planned division line (street)
15 Device 17A Device region 17B Peripheral excess region 19 Recess (groove)
19a Bottom 19b Side (inner wall)
21 Reinforcement portion (convex portion)
23 Adhesive tape 25 Substrate 27 Adhesive layer (glue layer)
29 Frame 29a Opening 31 Device chip 33 Chip 2 Cutting device 4 First chuck table (first holding table)
4a Holding surface 6 Frame (main body)
6a Upper surface 6b Recess (groove)
Reference Signs List 8: Holding member 8a: Suction surface 10: Clamp 12: Cutting unit 14: Housing 16: Cutting blade 18: Blade cover 20: Connection portion 22: Nozzle 24: Ultraviolet irradiation unit 26: Ultraviolet light 28: Liquid 30: Cleaning unit 32: Second chuck table (second holding table)
34 Frame (main body)
34a Upper surface 34b Recess (groove)
36 Holding member 36a Suction surface 38 Convex portion (protrusion)
40a, 40b, 40c Groove 42a, 42b Valve 44 Suction source 46 Fluid supply unit 48 Nozzle 50 Arm 52 Fluid 60 Groove forming unit (scribe line forming unit)
62: fixed member 64: cutter 64a: cutting blade 66: pressing member 66a: pressing surface

Claims (9)

A wafer processing method for processing a wafer, the 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 on an outer periphery surrounding the device regions and the recesses, comprising:
a tape application step of applying an adhesive tape having an adhesive layer that is cured by irradiation with ultraviolet light to the back 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 grooves on the front surface side of the reinforcing portion;
an adhesive layer hardening step of irradiating an annular region of the adhesive tape attached to the reinforcing portion with ultraviolet light before, during, or after the cutting step, thereby hardening a region of the adhesive layer in contact with the reinforcing portion;
a dividing step of dividing the reinforcement portion along the division line starting from the groove by applying an external force to the reinforcement portion;
a reinforcing portion removing step of removing the divided reinforcing portions by spraying a fluid onto the reinforcing portions. In the tape application step, a central portion of the adhesive tape is applied to the wafer, and an outer peripheral portion of the adhesive tape is applied to an annular frame;
2. The wafer processing method according to claim 1, wherein in the adhesive layer hardening step, the ultraviolet light is also irradiated onto areas of the adhesive tape that are not attached to the wafer and the frame, thereby hardening areas of the adhesive layer that are not in contact with the wafer and the frame. The wafer processing method according to claim 2, characterized in that in the adhesive layer hardening step, the adhesive layer is irradiated with the ultraviolet light while a liquid is in contact with the area of the adhesive layer that is not in contact with the wafer or the frame. The wafer processing method according to any one of claims 1 to 3, characterized in that the fluid is a cleaning liquid supplied from a cleaning unit that cleans the wafer. A wafer processing method according to any one of claims 1 to 4, characterized in that the fluid is sprayed from the center of the wafer toward the outer periphery. The wafer processing method according to any one of claims 1 to 5, characterized in that the fluid is a mixed fluid containing gas and liquid. A wafer processing method according to any one of claims 1 to 6, characterized in that in the dividing step, the adhesive tape is arranged along the unevenness by sucking the adhesive tape with the second chuck table, which has an unevenness at a position corresponding to the reinforcing portion of the wafer, while the wafer is supported by the second chuck table, thereby dividing the reinforcing portion. The wafer processing method according to any one of claims 1 to 7, further comprising a separation step of cutting the outer periphery of the device region in an annular shape with the cutting blade after the holding step and before the dividing step, thereby separating the device region from the reinforcing portion. The wafer processing method according to any one of claims 1 to 8, further comprising a scribe line forming step of forming a plurality of scribe lines in the reinforcing portion along the radial direction of the reinforcing portion after the cutting step and before the dividing step.

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