JP5523033B2 - Wafer processing method and annular convex portion removing device - Google Patents

Description

  The present invention relates to a wafer processing method and an annular convex portion removing device for removing an annular convex portion from a wafer having a circular concave portion and an annular convex portion surrounding the circular concave portion formed on the back surface.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a semiconductor wafer having a substantially disk shape, and devices such as IC and LSI are divided into these partitioned regions. Form. Then, the semiconductor wafer is cut into individual semiconductor chips (devices) by cutting the semiconductor wafer along a street with a cutting device.

  The divided wafer is formed to have a predetermined thickness by grinding the back surface before cutting along the street. In recent years, in order to achieve a reduction in weight and size of electrical equipment, it has been required to make the wafer thinner, for example, about 50 μm.

  Such thinly formed wafers are not as elastic as paper and are difficult to handle and may be damaged during transportation. Therefore, a grinding method in which only the back surface corresponding to the device region of the wafer is ground and a reinforcing annular convex portion is formed on the back surface of the wafer corresponding to the outer peripheral surplus region surrounding the device region is disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-173487. Proposed in the gazette.

  As a method of dividing the wafer having the annular convex portion formed on the outer periphery of the back surface along the street (scheduled line), there is a method in which the annular convex portion is removed and then the wafer is cut with a cutting blade from the front side of the wafer. It has been proposed (see JP 2007-19379 A).

  In Japanese Patent Application Laid-Open No. 2007-17379, as a method of removing the annular convex portion, a method of removing the annular convex portion by grinding, and after cutting the interface between the circular concave portion and the annular convex portion with a cutting blade into a circular shape, A method for removing the portion is disclosed.

JP 2007-173487 A JP 2007-19379 A

  Recently, in the removal of the annular convex portion by grinding, the bottom of the circular concave portion is scratched, or, for example, after the circular concave portion is formed at the center of the back surface of the wafer and the annular convex portion surrounding the circular concave portion is formed. In a wafer in which a metal film is formed in a circular recess, it has been found that a grinding wheel entrains the metal film during grinding of the annular protrusion and causes grinding failure.

  On the other hand, in order to cut the interface between the circular concave portion and the annular convex portion with the cutting blade, it is necessary to reinforce the wafer by providing a protective member in order not to damage the wafer after removing the annular convex portion as the reinforcing portion. There is. However, Patent Document 2 does not disclose a specific method for peeling the annular convex portion from the protective member, and a proposal for the method has been desired.

  The present invention has been made in view of these points, and the object of the present invention is to remove the annular convex portion without damaging the wafer and to prevent the wafer from being damaged in the subsequent process. It is providing the processing method and an annular convex part removal apparatus.

According to the first aspect of the present invention, there is provided a wafer processing method for removing a ring-shaped convex portion from a wafer having a circular concave portion formed on the back surface and an annular convex portion surrounding the circular concave portion. A wafer unit forming step for forming a wafer unit by attaching an adhesive tape to the annular frame and attaching an outer peripheral portion of the adhesive tape to an annular frame; and dividing to form a dividing groove at the boundary between the circular recess and the annular protrusion and placing step of placing the groove forming step, a circular recess of the wafer via the PSA tape chuck table having a slightly smaller holding surface than circular recess, after performing the placing step, said plurality The claw of the wafer is positioned at the height of the annular convex portion of the wafer placed on the chuck table, and the claw is moved toward the center of the wafer to push the annular convex portion of the wafer. A centering step of centering of the wafer and the chuck table, wherein after the centering step was performed, a frame fixing means disposed on the outer periphery of the chuck table sucks hold circular recess in the chuck table A holding step for fixing the annular frame, a projecting step for projecting the chuck table relative to the frame fixing means by relatively moving the frame fixing means and the chuck table in a vertical direction, and a plurality of claws on the wafer. An intrusion step in which the nail is moved from the outer peripheral side to the interface height between the annular protrusion and the adhesive tape, and then the nail is moved in the wafer center direction to enter the interface between the annular protrusion and the adhesive tape; Removing step of removing the annular projection from the wafer unit by moving the claw of the wafer in a direction away from the wafer , The wafer processing method, characterized by comprising a are provided.

According to the second aspect of the present invention, the circular concave portion formed on the back surface of the wafer corresponding to the device area of the wafer surface where the plurality of devices are partitioned by the division planned lines, and the annular convex portion surrounding the circular concave portion. A wafer processing method for removing an annular convex portion from a wafer having a wafer unit, wherein a wafer unit is formed by attaching an adhesive tape to a back surface of the wafer and attaching an outer peripheral portion of the adhesive tape to an annular frame. Forming a cutting groove in the vicinity of the boundary between the circular concave portion and the annular convex portion by forming the circular concave portion from the surface of the wafer along the line to be divided and half cutting the annular convex portion. A step of forming a dividing groove, and a circular recess of the wafer via the adhesive tape on a chuck table having a holding surface slightly smaller than the circular recess. And placing step of location, after carrying out the placing step, positioning a plurality of pawls to the height of the annular convex portion of the wafer placed on the chuck table, to move the pawl in the wafer center direction After the centering step for centering the wafer and the chuck table by pushing the annular convex portion of the wafer and performing the centering step, the circular recess is sucked and held by the chuck table. A holding step for fixing the annular frame by a frame fixing means disposed on the outer periphery of the chuck table, and a relative movement of the frame fixing means and the chuck table in the vertical direction to move the chuck table to the frame fixing means. a projecting step of projecting for, located interfacial height of the adhesive tape and the annular protrusion a plurality of pawl from the outer periphery of the wafer And moving the claw toward the wafer center to enter the interface between the annular convex portion and the adhesive tape, and moving the plurality of claws in a direction away from the wafer to move the annular convex portion to the wafer. a removal step of removing from the wafer unit, the wafer processing method, characterized by comprising a are provided.

  Preferably, the pressure-sensitive adhesive tape is composed of an ultraviolet curable pressure-sensitive adhesive tape, and the wafer processing method includes irradiating the annular convex portion with ultraviolet rays while masking the circular concave portion after performing the dividing groove forming step. It further includes an adhesive strength lowering step for reducing the adhesive strength of the region corresponding to the annular convex portion of the adhesive tape.

  Preferably, the diameter of the holding surface of the chuck table is set to be 1 to 3 mm smaller than the diameter of the circular recess.

  According to the wafer processing method of the present invention, the holding surface of the chuck table protrudes from the frame fixing means while the circular concave portion is sucked and held, so that the annular frame is pulled down relative to the holding surface of the chuck table. Since the adhesive tape attached to the back of the wafer slightly expands as the annular frame is pulled down, the claw easily enters the interface between the annular convex part and the adhesive tape, and the circular concave part is sucked and held by the chuck table. It will not be damaged.

  Further, even after the annular convex portion that is the reinforcing portion is removed, the wafer is supported by the annular frame via the adhesive tape that is the protective member, so that the wafer is not damaged and handling of the wafer is facilitated.

  According to the second aspect of the present invention, the dividing groove is formed near the boundary between the circular concave portion and the annular convex portion by full-cutting the circular concave portion along the line to be divided and half-cutting the annular convex portion. The dividing step of dividing the device into individual devices can be omitted.

Further, according to the invention of claim 1 and 2, wherein, for performing the centering of the wafer and the chuck table by pushing the annular projection of the wafer at a plurality of claws, the centers of the annular frame of the wafers Even in the wafer unit in a shifted state, the circular concave portion can be reliably placed on the chuck table, and the removal of the annular convex portion can be prevented from failing.

According to the invention described in claim 3, since the adhesive force of the adhesive tape is reduced in advance in a region corresponding to the annular convex portion, the annular convex portion can be easily removed from the wafer unit.

According to the invention described in claim 4 , since the diameter of the chuck table is smaller by 1 to 3 mm than the diameter of the circular recess, the circular recess is easily fitted to the chuck table.

It is a surface side perspective view of a semiconductor wafer. It is a back surface side perspective view of a semiconductor wafer. It is an external appearance perspective view of a cyclic | annular convex part removal apparatus. It is a perspective view of a cyclic | annular convex part removal apparatus. 5A is a side view of the claw assembly, and FIG. 5B is a bottom view of FIG. 5A. It is a flowchart of the processing method of the wafer of 1st Embodiment of this invention. It is a flowchart of the processing method of the wafer of 1st Embodiment of this invention. It is explanatory drawing of a wafer unit formation step. It is a perspective view of a wafer unit. It is explanatory drawing of the dividing groove formation step of 1st Embodiment. It is explanatory drawing of an adhesive force fall step. It is a figure which shows the vertical movement part arrange | positioned around the chuck table and the chuck table. It is explanatory drawing of a mounting step. It is explanatory drawing of a center alignment step. It is explanatory drawing of a holding step. It is explanatory drawing of a protrusion step. It is explanatory drawing of an intrusion step. It is explanatory drawing of a removal step. It is explanatory drawing of a cyclic | annular convex part discard step. It is explanatory drawing of an air blow step. It is a principal part perspective view of the cutting device which shows a wafer division | segmentation step. It is a flowchart of 2nd Embodiment of this invention. It is a flowchart of 2nd Embodiment of this invention. It is explanatory drawing of the dividing groove formation step of 2nd Embodiment. It is a top view of the wafer in which the parting groove was formed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front perspective view of a semiconductor wafer 11 formed of silicon. A plurality of streets (division lines) 13 are formed in a lattice pattern on the surface 11 a of the semiconductor wafer 11, and devices 15 such as ICs and LSIs are formed in each region partitioned by the plurality of streets 13. Yes.

  The surface 11 a of the semiconductor wafer 11 includes a device region 17 in which the device 15 is formed, and an outer peripheral surplus region 19 that surrounds the device region 17. A notch 21 is formed on the outer periphery of the semiconductor wafer 11 as a mark indicating the crystal orientation of the silicon wafer.

  FIG. 2 shows a rear perspective view of the semiconductor wafer 11. On the back surface 11b of the semiconductor wafer 11, the back surface 11b corresponding to the device region 17 is ground to form a circular recess 23 having a thickness of about 50 μm, and the outer peripheral side of the circular recess 23 remains without being ground. An annular convex portion 25 including the outer peripheral surplus region 19 is formed. The annular convex part 25 acts as a reinforcing part, for example, the thickness is 700 μm.

  Referring to FIG. 3, an external perspective view of the annular convex portion removing device 2 is shown. A cassette insertion slot 6 having a handle 8 and a touch panel 10 as an operation and display screen are disposed in the housing 4 of the annular convex portion removing device 2.

  Referring to FIG. 4, a perspective view of the mechanism part of the annular convex part removing device 2 is shown. Reference numeral 12 denotes an ultraviolet irradiation unit (UV irradiation unit) whose upper surface functions as a cassette mounting table 14 for mounting a cassette containing a wafer. The ultraviolet irradiation unit 12 and the cassette mounting table 14 can be moved up and down by an elevator mechanism (not shown).

  16 is a push-pull that takes out a wafer unit, which will be described later, from a cassette (not shown) mounted on the cassette mounting table 14 and conveys it to the chuck table 26, and accommodates the processed wafer unit in the cassette. It is mounted on an L-shaped member 18 that moves in the Z-axis direction.

  The L-shaped member 18 is attached to the Y-axis moving member 22 via a Z-axis moving mechanism 20 composed of a ball screw and a pulse motor. The Y-axis moving member 22 is moved in the Y-axis direction by a Y-axis moving mechanism 24 composed of a ball screw and a pulse motor.

  Around the chuck table 26, a vertical moving portion 27 that moves in the vertical direction (Z-axis direction) is disposed. The vertical moving unit 27 is configured by alternately arranging electromagnets 30 and plate members 31, and the plate member 31 is connected to a piston rod 82 of an air cylinder 80 as shown in FIG. 12.

  By operating the air cylinder 80, the vertical moving unit 27 is moved between the ascending position shown in FIG. 12 and the drawing position where the vertical moving unit 27 is drawn down with respect to the holding surface 26 a of the chuck table 26.

  The holding surface 26 a of the chuck table 26 has a diameter smaller by 1 to 3 mm than the diameter of the circular recess 23 of the wafer 11, and only the circular recess 23 of the wafer 11 can be sucked and held by the chuck table 26 via the adhesive tape 58. It is like that.

  Referring again to FIG. 4, a pair of centering guides 28 for centering the wafer unit pulled out from the cassette by the push-pull 16 so as to sandwich the vertical moving portion 27 is provided. By moving the centering guides 28 toward each other, preliminary centering of the wafer unit on the chuck table 26 is performed.

  Reference numeral 32 denotes a claw assembly. As shown in detail in FIG. 5, a Z-axis moving member 34 that moves in the Z-axis direction, a rectangular member 36 fixed to the tip of the Z-axis moving member 34, And four guide members 38 that extend 90 degrees apart from each other.

  A ball screw 40 is attached to each guide member 38, and one end of the ball screw 40 is connected to a pulse motor accommodated in a rectangular member 36. The ball screw 40 and the pulse motor constitute first claw moving means 42.

  Each ball screw 40 is screwed with a nut accommodated in a horizontal moving member 44. When the pulse motor of the first claw moving means 42 is driven, each ball screw 40 is rotated and the horizontal moving member 44 is in a standby state. It is moved between a position and an operating position that is close to each other in the radial direction.

  A claw 46 is attached to each horizontal moving member 44. As shown in FIG. 5 (B), when the four claws 46 are moved to the operating position, a ring 47 is formed. Each horizontal moving member 44 is formed with an air ejection port 48 that ejects air toward the claw 46.

  Referring again to FIG. 4, the Z-axis moving member 34 is attached to the Y-axis moving member 50 via a Z-axis moving mechanism (second claw moving means) 52 composed of a ball screw and a pulse motor.

  The Y-axis moving member 50 is moved in the Y-axis direction by a Y-axis moving mechanism 54 composed of a ball screw and a pulse motor. Adjacent to the chuck table 26, an annular convex portion recovery case 55 for recovering the annular convex portion removed from the wafer unit is disposed.

  Next, the wafer processing method according to the first embodiment of the present invention will be described in detail with reference to the flowcharts of FIGS. 6 and 7 and FIGS.

  First, a wafer unit forming step is performed in step S10 of FIG. That is, as shown in FIG. 8, an ultraviolet curable pressure-sensitive adhesive tape 58 is attached to the back surface of the wafer 11 having a circular concave portion 23 formed in the center of the back surface and an annular convex portion 25 surrounding the circular concave portion 23, and ultraviolet curing is performed. The outer peripheral portion of the mold adhesive tape 58 is attached to the annular frame 56 so as to close the opening 56 a of the annular frame 56.

  Actually, the back surface of the wafer 11 and the annular frame 56 are pasted on an ultraviolet curable adhesive tape 58 placed on a table or the like as shown by an arrow A, and a wafer unit 59 as shown in FIG. Form.

  Subsequently, it progresses to step S11 and a dividing groove is formed in the boundary part of the circular recessed part 23 and the annular convex part 25 of the wafer 11 using a cutting blade or a laser beam. For example, as shown in FIG. 10, the circular recess 23 of the wafer 11 is sucked and held by the chuck table 60 of the cutting apparatus having the step 61 via the adhesive tape 58, and the annular frame 56 is fixed by the clamp 62.

  A cutting blade 70 is attached to the tip of a spindle 68 rotatably accommodated in a spindle housing 66 of the cutting unit 64. The chuck table 60 is rotated at a low speed while cutting the wafer 70 to a predetermined depth while rotating the cutting blade 70 at a high speed, and the boundary portion between the circular concave portion 23 and the annular convex portion 25 is circular from the surface 11a side of the wafer 11. To form a circular dividing groove. In the state where the circular dividing groove is formed, the circular concave portion 23 and the annular convex portion 25 of the wafer 11 remain adhered to the adhesive tape 58.

  This dividing groove forming step is not limited to the circle cutting by the cutting blade 70, and the dividing groove forming step may be performed by ablation processing with a laser beam having a wavelength that is absorptive to the wafer 11. .

  After completion of the dividing groove forming step in step S11, the process proceeds to step S12, and the adhesive strength reducing step is performed. That is, as shown in FIG. 11, a wafer unit 59 is inserted into the UV irradiation unit 12 and a mask 74 having a circular opening 78 corresponding to the annular convex portion 25 is used to turn on the ultraviolet lamp 72 to thereby form a circular opening. Ultraviolet light is applied to the ultraviolet curable adhesive tape 58 to which the annular convex portion 25 is attached via 78 to reduce the adhesive strength of the region corresponding to the annular convex portion 25 of the adhesive tape 58.

  After the step S12 for reducing the adhesive force is completed, the process proceeds to step S13 where the wafer unit 59 is placed on the chuck table 26 having a holding surface 26a slightly smaller (1 to 3 mm smaller) than the circular recess 23 of the wafer 11 as shown in FIG. Is placed. At this time, the electromagnet 30 as the frame fixing means remains non-excited (off).

  When this placement step is performed, the center of the wafer 11 and the center position of the annular frame 56 may not coincide with each other due to variations in the position of the wafer on the adhesive tape 58. Then, it progresses to step S14 and a centering step is implemented.

  That is, the claw assembly 32 shown in FIG. 14 (A) is lowered in the direction of arrow A, and the plurality of claws 46 shown in FIG. 14 (B) are placed on the annular convex portion 25 of the wafer 11 placed on the chuck table 26. Positioned from the outer peripheral side of the wafer 11 at a height and moving the plurality of claws 46 in the direction of the wafer center at the same speed as indicated by the arrow B, the annular protrusion 25 of the wafer 11 is pushed and the center of the wafer 11 is moved. The center of the chuck table 26 is aligned.

  When this positioning step is completed, the circular concave portion 23 of the wafer 11 is fitted to the holding surface 26a of the chuck table 26. Therefore, the process proceeds to step S15 and the circular concave portion 23 of the wafer 11 is sucked and held by the chuck table 26. A holding step is performed in which the electromagnet 30 as a frame fixing means disposed on the outer periphery of the table 26 is excited (turned on), and the annular frame 56 is fixed by the electromagnet 30.

  Next, the process proceeds to step S16, and a projecting step is performed in which the frame fixing means and the chuck table 26 are relatively moved in the vertical direction to cause the chuck table 24 to project with respect to the frame fixing means.

  That is, as shown in FIG. 16, the electromagnet 30 as the frame fixing means is pulled down in the direction of arrow A, and the holding surface 26a of the chuck table 26 is protruded from the electromagnet 30 as the frame fixing means. Thereby, since the annular frame 56 fixed by the electromagnet 30 is also pulled down, the adhesive tape 58 adhered to the back surface of the wafer 11 slightly extends in the radial direction.

  The frame fixing means is not limited to the electromagnet 30 and may be a clamp 62 used in a cutting apparatus as shown in FIG. Moreover, the structure which raises / lowers the chuck table 26, without moving the fixing means 30 may be sufficient.

  Next, the process proceeds to step S17, where the plurality of claws 46 are positioned at the interface height between the annular convex portion 25 and the adhesive tape 58 from the outer peripheral side of the wafer 11 as shown in FIG. Then, the wafer is moved toward the center of the wafer to enter the interface between the annular protrusion 25 and the adhesive tape 58.

  Since the adhesive tape 58 is extended in the radial direction in step S <b> 16, the claw 46 easily enters the interface between the annular convex portion 25 and the adhesive tape 58, and the circular concave portion 23 of the wafer 11 is sucked and held by the chuck table 26. Therefore, it will not be damaged.

  After the claw 46 has entered the interface between the annular convex portion 25 and the adhesive tape 58 in this way, the plurality of claws 46 are brought close to each other in the arrow B direction as shown in FIG. The annular protrusion 25 is pulled up and removed from the wafer unit 59 (step S18).

  After the annular protrusion 25 is removed from the wafer unit 59 in this way, after the claw assembly 32 is moved in the direction of arrow D as shown in FIG. 19, the annular protrusion 25 is positioned on the annular protrusion housing case 55. The claw 46 is moved in the direction of arrow E, and the annular convex portion 25 is discarded in the annular convex portion accommodating case 55 (step S19).

  After carrying out the annular convex portion discarding step of step S19, it is preferable to clean the claw 46 by ejecting air from the air ejection port 48 to the holding surface of the claw 46 as shown in FIG.

  Next, the process proceeds to step S20, where the wafer 11 from which the annular convex portion 25 has been removed is cut with a cutting blade and divided into individual devices. That is, as shown in FIG. 21, the wafer 11 from which the annular convex portion 25 has been removed is sucked and held by the chuck table 60A of the cutting apparatus, and the cutting blade 70A is rotated at a high speed while the chuck table 60A is processed and fed in the direction of the arrow X1. Then, the wafer 11 is divided into individual devices 15 by being cut into the wafer 11.

  Next, the wafer processing method according to the second embodiment of the present invention will be described in detail with reference to FIGS. In the processing method of this embodiment, the dividing groove forming step of step S31 is different from the dividing groove forming step of step S11 of the first embodiment. Step S30 is the same as Step S10 of the first embodiment, and Steps S32 to S39 are the same as Step S12 to Step S19 of the first embodiment, so the description thereof is omitted.

  In the dividing groove forming step of step S31, as shown in FIG. 24, the cutting blade 70A rotating at high speed in the direction of arrow A while feeding the chuck table 60 in the direction indicated by arrow X1 is put on the planned dividing line 13 of the wafer 11. Then, the wafer 11 is cut, the circular concave portion 23 is fully cut (completely cut), and the annular convex portion 25 is half cut.

  FIG. 25 shows a plan view of the wafer 11 in a state where the dividing grooves 86 are formed along all the planned dividing lines 13. Since the concave portion 23 of the wafer 11 is completely cut and the annular convex portion 25 is incompletely cut, a dividing groove 88 indicated by a bold line is formed near the boundary between the circular concave portion 23 and the annular convex portion 25.

  Therefore, in the present embodiment, the outer peripheral portion is removed from the wafer unit 59 from the dividing groove 88 in the removing step of step S38. Since the wafer 11 is divided into the individual devices 15 in the dividing groove forming step of this embodiment, the dividing step of Step S20 of the first embodiment can be omitted in this embodiment.

2 annular convex removing device 11 semiconductor wafer 12 UV irradiation unit 13 street (division planned line)
15 device 23 circular recess 25 annular protrusion 26 chuck table 30 electromagnet 32 claw assembly 42 first claw moving means 52 second claw moving means 56 annular frame 58 UV curable adhesive tape 59 wafer unit 70, 70A cutting blade

Claims (4)

A wafer processing method for removing an annular convex portion from a wafer having a circular concave portion formed on a back surface and an annular convex portion surrounding the circular concave portion,
A wafer unit forming step of sticking an adhesive tape to the back surface of the wafer, and mounting a peripheral unit of the adhesive tape on an annular frame to form a wafer unit;
A dividing groove forming step for forming a dividing groove at a boundary between the circular concave portion and the annular convex portion;
A mounting step of mounting the circular recess of the wafer via the adhesive tape on a chuck table having a holding surface slightly smaller than the circular recess;
After performing the placing step, the plurality of claws are positioned at the height of the annular convex portion of the wafer placed on the chuck table, and the annular convex portion of the wafer is moved by moving the claws toward the center of the wafer. A centering step for centering the wafer and the chuck table by pushing the part;
A holding step of sucking and holding the circular recess with the chuck table and fixing the annular frame with frame fixing means disposed on the outer periphery of the chuck table after performing the centering step;
A projecting step for projecting the chuck table relative to the frame fixing means by relatively moving the frame fixing means and the chuck table in a vertical direction;
An intrusion in which a plurality of claws are positioned from the outer peripheral side of the wafer to the interface height between the annular convex portion and the adhesive tape, and then the claws are moved toward the wafer center to enter the interface between the annular convex portion and the adhesive tape. Steps,
Removing the annular protrusion from the wafer unit by moving the plurality of claws in a direction away from the wafer;
The wafer processing method, characterized by comprising a. The annular convex portion is removed from a wafer having a circular concave portion formed on the back surface of the wafer corresponding to the device area on the wafer surface where a plurality of devices are divided by the division lines, and an annular convex portion surrounding the circular concave portion. A method of processing a wafer,
A wafer unit forming step of sticking an adhesive tape to the back surface of the wafer, and mounting a peripheral unit of the adhesive tape on an annular frame to form a wafer unit;
A dividing groove that forms a dividing groove in the vicinity of a boundary portion between the circular concave portion and the annular convex portion by full-cutting the circular concave portion from the surface of the wafer along the division line and half-cutting the annular convex portion. Forming step;
A mounting step of mounting the circular recess of the wafer via the adhesive tape on a chuck table having a holding surface slightly smaller than the circular recess;
After performing the placing step, the plurality of claws are positioned at the height of the annular convex portion of the wafer placed on the chuck table, and the annular convex portion of the wafer is moved by moving the claws toward the center of the wafer. A centering step for centering the wafer and the chuck table by pushing the part;
A holding step of sucking and holding the circular recess with the chuck table and fixing the annular frame with frame fixing means disposed on the outer periphery of the chuck table after performing the centering step;
A projecting step for projecting the chuck table relative to the frame fixing means by relatively moving the frame fixing means and the chuck table in a vertical direction;
After positioning a plurality of pawls from the outer peripheral side of the wafer to interfacial height of the adhesive tape and the annular convex portion, thereby moving the pawl to the wafer center direction penetrate the interface of the annular convex portion and the adhesive tape Intrusion step,
Removing the annular protrusion from the wafer unit by moving the plurality of claws in a direction away from the wafer;
The wafer processing method, characterized by comprising a. The adhesive tape is composed of an ultraviolet curable adhesive tape,
After carrying out the dividing groove forming step, an adhesive force lowering step for reducing the adhesive strength of the region corresponding to the annular convex portion of the adhesive tape by irradiating the annular convex portion with ultraviolet rays while masking the circular concave portion. Furthermore the wafer processing method according to claim 1 or 2 with. The wafer processing method according to claim 1, wherein a diameter of the holding surface of the chuck table is smaller by 1 to 3 mm than a diameter of the circular recess.

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