Wafer dividing method

Abstract

To remove a resin covering a cutting groove of a wafer in a short time and enhance productivity.SOLUTION: A wafer dividing method sequentially performs: a first holding step of making a first chuck table of a cutting device hold a wafer; a cutting groove formation step of cutting the surface of the wafer by a cutting blade into a predetermined depth and forming a bottomed cutting groove; a water-soluble resin filling step of coating the surface of the wafer with a water-soluble liquid resin, drying the water-soluble liquid resin, and thereby filling the cutting groove with the water-soluble resin; a protective sheet bonding step of bonding a protective sheet onto the surface of the wafer; a second holding step of making a second chuck table of a grinding device hold the wafer; a grinding step of grinding the rear face of the wafer held by the second chuck table by a grinding stone and exposing the cutting groove onto the rear face of the wafer, and thereby dividing the wafer into individual chips; and a water-soluble resin removal step of jetting cleaning water to the wafer divided into the plurality of chips and removing the water-soluble resin.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a wafer dividing method for dividing a wafer along streets (planned dividing lines). [Background technology]

[0002] For example, in the manufacturing process of semiconductor devices, the surface of a disk-shaped semiconductor wafer (hereinafter simply referred to as a "wafer") is divided into multiple device regions by grid-like streets (planned division lines), and devices such as ICs and LSIs are formed in each device region. Then, by dividing the wafer with many devices formed in this way along the streets, multiple chips are obtained. The chips divided in this way are packaged and widely used in various electronic devices such as personal computers and smartphones.

[0003] In recent years, there has been a demand for smaller and lighter electronic devices, and the chips used in these electronic devices are becoming thinner. Chips are thinned by grinding the backside of the wafer before it is separated, but when the thinned wafer is separated into individual chips by dicing or other methods, there is a problem that chips are prone to occur.

[0004] As a method for dividing wafers that solves the above problems, a dividing technique called pre-dicing has been developed and is already in practical use (see, for example, Patent Document 1). This pre-dicing is a method in which, before grinding the backside of the wafer, grooves of a predetermined depth (a depth that does not completely cut the wafer) are formed from the front side of the wafer along the streets, and with a protective sheet attached to the front side of the wafer, the backside of the wafer is ground to expose the grooves, thereby dividing the wafer into individual chips.

[0005] However, in the method of dividing the wafer into individual chips by pre-dicing, grinding continues until the chips reach the desired thickness even after the cutting grooves are exposed on the back surface of the wafer, so abrasive grains that have come off the grinding wheel and grinding debris from the wafer get into the cutting grooves (gaps between adjacent chips), causing problems such as soiling the side surfaces of the chips and causing chipping or damage to the chips.

[0006] Therefore, Patent Document 2 proposes filling the kerfs of the wafer with an interference prevention material such as a curable liquid resin. Also, Patent Document 3 proposes a method in which a solventless hydrophilic resin is applied in a liquid or viscoelastic state to the surface of the wafer where the kerfs are formed, and cured, and then the back surface of the wafer is ground to divide the wafer into individual chips, and then the hydrophilic resin is removed from each chip by contacting it with hot water of 40°C or higher. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 64-038209 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-176822 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-224659 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the wafer dividing methods proposed in Patent Documents 2 and 3 have the problem that it takes time to remove the hardenable liquid resin or hydrophilic resin that is the interference prevention member, resulting in poor productivity.

[0009] The present invention has been made in view of the above problems, and its object is to provide a wafer dividing method that can remove the resin covering the cut grooves of the wafer in a short time, thereby increasing productivity. [Means for solving the problem]

[0010] The invention of claim 1 is a wafer dividing method for obtaining a plurality of chips by dividing a wafer having a surface divided by streets and having devices formed in each of the plurality of regions along the streets, the method comprising the steps of: a first holding step of holding the wafer with the surface facing up on a first chuck table of a cutting device; a cut groove forming step of cutting the surface of the wafer to a predetermined depth along the streets with a cutting blade of the cutting device to form bottomed cut grooves; a water-soluble resin filling step of applying a water-soluble liquid resin to the surface of the wafer and drying it to form a water-soluble resin layer; a protective sheet applying step of applying a protective sheet to the surface of the wafer; a second holding step of holding the wafer with the back side facing up on a second chuck table of a grinding device; a grinding step of grinding the wafer held on the second chuck table with a grinding wheel to expose the cut grooves on the back side of the wafer, thereby dividing the wafer into individual chips; and a water-soluble resin removing step of spraying cleaning water onto the wafer divided into a plurality of chips to remove the water-soluble resin layer. [Effects of the Invention]

[0011] According to the invention of claim 1, in the cutting groove forming step, a bottomed cutting groove (half-cut groove) is formed on the front surface of the wafer (the surface on which the device is formed), and the cutting groove of the wafer is filled with water-soluble resin in the water-soluble resin filling step. In the grinding step, the back surface of the wafer is ground to expose the cutting groove. In the water-soluble resin removal step, the water-soluble resin filled in the exposed cutting groove is dissolved and removed with cleaning water, thereby dividing the wafer into multiple chips. This allows the relatively small amount of water-soluble resin layer filled in the cutting groove to be dissolved and removed in a short period of time. As a result, chip productivity can be improved. Furthermore, in the cutting step, because the cutting groove is filled with water-soluble resin, adhesion of cutting debris to the side surfaces of the divided chips can be prevented. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. [Figure 2] 3 is a flowchart showing the procedure of a wafer dividing method according to the present invention. [Figure 3] 3 is a side cross-sectional view showing a first holding step in the wafer dividing method according to the present invention. FIG. [Figure 4] 10 is a side cross-sectional view showing a cut groove forming step in the wafer dividing method according to the present invention. FIG. [Figure 5] 10 is a side cross-sectional view showing a cutting groove cleaning step in the wafer dividing method according to the present invention. FIG. [Figure 6] 10 is a side cross-sectional view showing a water-soluble resin filling step in the wafer dividing method according to the present invention. FIG. [Figure 7] 1 is a side cross-sectional view showing a protective sheet adhering step in the wafer dividing method according to the present invention. FIG. [Figure 8] 4 is a side cross-sectional view showing a second holding step in the wafer dividing method according to the present invention. FIG. [Figure 9] 3 is a side cross-sectional view showing a grinding step in the wafer dividing method according to the present invention. FIG. [Figure 10] 10 is a side cross-sectional view showing a water-soluble resin removing step in the wafer dividing method according to the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0014] The wafer W to be divided by the dividing method according to the present invention is, for example, a thin, disk-shaped member made of single-crystal silicon (Si), as shown in Fig. 1, and its surface (the upper surface in Fig. 1) is divided into a plurality of rectangular regions by mutually orthogonal streets (planned dividing lines) L1, L2 arranged in a lattice pattern, and a device D such as an IC or LSI is formed in each rectangular region. Note that, in addition to silicon (Si), silicon carbide (SiC), glass, ceramics, sapphire, etc. may be used as the material for the wafer W.

[0015] [Wafer division method] The wafer dividing method according to the present invention will be described below with reference to FIGS.

[0016] The method for dividing a wafer W according to the present invention includes the following steps, as shown in FIG. 1) First holding step (step S1) 2) Cutting groove formation process (Step S2) 3) Cutting groove cleaning process (Step S3) 4) Water-soluble resin filling process (step S4) 5) Protective sheet attachment process (step S5) 6) Second holding process (step S6) 7) Grinding process (Step S7) 8) Water-soluble resin removal process (step S8) The above steps are carried out in order to divide the wafer W (see FIG. 1) into a plurality of chips C (see FIG. 11). Each step will be explained below.

[0017] 1) First holding step: The first holding step is a step of holding the wafer W on the holding surface of a disk-shaped first chuck table 1 of the cutting device, as shown in Fig. 3. In Fig. 3 and Fig. 4, the left-right direction is the X-axis direction, the direction perpendicular to the paper surface is the Y-axis direction, and the up-down direction is the Z-axis direction.

[0018] Here, a porous disk-shaped porous member 1A is incorporated in the upper center of the first chuck table 1, and the upper surface of this porous member 1A constitutes a holding surface for holding the wafer W. And the porous member 1A is connected to a suction source 2 such as a vacuum pump or an ejector, and the wafer W is placed on the holding surface of its upper surface with the surface (the surface on which the device D (see FIG. 1) is formed) facing up. Then, since the porous member 1A is evacuated by the suction source 2, a negative pressure is generated in the porous member 1A, and the wafer W is sucked and held on the holding surface of the porous member 1A by this negative pressure.

[0019] Also, the first chuck table 1 is horizontally movable in the X-axis direction (cutting feed direction) by an X-axis moving mechanism 3 and is also horizontally movable in the Y-axis direction (indexing direction) by a Y-axis moving mechanism (not shown). The X-axis moving mechanism 3 and the Y-axis moving mechanism (not shown) are constituted by a known ball screw mechanism or the like.

[0020] 2) Cutting groove forming step: The cutting groove forming step is a step of cutting (half-cutting) the surface of the wafer W held on the first chuck table 1 of the cutting device in the first holding step to a predetermined depth h by a cutting blade 11 provided in a cutting unit 10 shown in FIG. 4 to form a grid-shaped bottomed cutting groove Wa. In this cutting groove forming step, the depth h of the grid-shaped bottomed cutting groove Wa formed on the surface of the wafer W is set to a depth that does not completely cut the wafer W and is smaller than the thickness t of the wafer W (h < t). Therefore, in the wafer W after the cutting groove Wa is formed, an uncut portion W1 having a thickness of (t - h) remains, and the wafer W maintains its initial disk shape by this uncut portion W1.

[0021] Here, the cutting blade 11 is a thin, disk-shaped cutting tool attached to the tip of a rotatable spindle 12 arranged along the Y axis, and the spindle 12 rotates at high speed together with the cutting blade 11 by a spindle motor (not shown) built into the housing 13 of the cutting unit 10. The cutting unit 10 is supported by a Z-axis movement mechanism (not shown) so as to be movable in the Z-axis direction (cutting direction). The housing 13 is provided with jet nozzles 14 and 15 that jet cutting water toward the cutting blade 11 during cutting, and these jet nozzles 14 and 15 are each connected to a cutting water supply source 16. Pure water is preferably used as the cutting water.

[0022] Thus, a cut groove Wa of a predetermined depth h is formed on the surface of the wafer W, for example, along one street L1 (see FIG. 1) by cutting (half cutting) with the cutting blade 11 rotating at high speed. That is, when the first chuck table 1 moves along the X-axis direction (the direction of the arrow in FIG. 2) together with the wafer W by the X-axis moving mechanism 3 and is positioned below the cutting unit 10, an image of the surface of the wafer W is captured by an imaging unit (not shown) provided in the cutting unit 10. Then, when an image of the surface of the wafer W is obtained by the imaging unit, the street L1 to be cut is detected by pattern matching processing based on the image.

[0023] As described above, when the street L1 of the wafer W is detected, the position of the cutting blade 11 of the cutting unit 10 in the Y-axis direction is determined by a Y-axis moving mechanism (not shown), and the position of the cutting blade 11 in the Y-axis direction is aligned with the position of the street L1 to be cut.

[0024] Then, from the above state, the cutting blade 11 is rotated at high speed while being lowered by a predetermined cutting depth by the Z-axis movement mechanism, and the first chuck table 1 and the wafer W held thereon are moved in the X-axis direction by the X-axis movement mechanism 3. The wafer W is then cut along the streets L1 by the cutting blade 11. After this operation has been performed for all the streets L1 in one direction, the first chuck table 1 and the wafer W held thereon are rotated by 90° by the rotation mechanism (motor 9 shown in FIGS. 5 and 6), and the wafer W is similarly cut along streets L2 (see FIG. 1) in the other direction perpendicular to the street L1 where cutting has been completed. As a result, cut grooves Wa of a predetermined depth h are formed in a grid pattern on the surface of the wafer W along the streets L1 and L2.

[0025] 3) Cutting groove cleaning process: The kerf cleaning process is a process in which kerf grooves Wa of a predetermined depth h, which have been formed in a grid pattern on the surface of the wafer W in the preceding kerf groove forming process, are cleaned with cleaning water as shown in Fig. 5. Above the first chuck table 1, a spray nozzle 5 connected to a cleaning water supply source 4 and a spray nozzle 7 connected to an air supply source 6 are disposed. A motor 9, which serves as a rotation drive source, is connected to a rotation shaft 8 extending vertically downward from the center of the first chuck table 1. Pure water is preferably used as the cleaning water.

[0026] In this cutting water cleaning process, the first chuck table 1 and the wafer W held thereon are rotated by the motor 9 around their axis in the direction of the arrow in the drawing at a predetermined speed, and cleaning water supplied from the cleaning water supply source 4 is sprayed from the spray nozzle 5 toward the lattice-shaped, bottomed cut grooves Wa formed on the surface of the wafer W, cleaning each cut groove Wa with the cleaning water. Cleaning the cut grooves Wa with this cleaning water removes cutting chips that are generated during the cutting process of the wafer W and that have adhered to the cut grooves Wa. The cutting chips and cleaning water adhering to the cut grooves Wa are then blown away and removed by air supplied from the air supply source 6 and sprayed from the spray nozzle 7 toward the surface of the wafer W.

[0027] 4) Water-soluble resin filling process: The water-soluble resin filling step is a step of applying a water-soluble liquid resin r to the surface of the wafer W and drying it to fill the cut grooves Wa of the wafer W with a water-soluble resin layer R, as shown in Fig. 6. The water-soluble liquid resin r may be polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), or the like.

[0028] In the water-soluble resin filling step, the first chuck table 1 and the wafer W held thereon are rotated by the motor 9 around their axis in the direction of the arrow in the figure at a predetermined speed, and water-soluble liquid resin r, supplied from a liquid resin supply source 17 to a nozzle 18, is dripped from the nozzle 18 toward the center of the top surface of the wafer W. The water-soluble liquid resin r dripped onto the center of the top surface of the wafer W spreads radially outward of the wafer W due to centrifugal force, filling the grid-like, bottomed cut grooves Wa formed on the surface of the wafer W with a water-soluble resin layer R. The first chuck table 1 is rotated at a high speed of 2000 rpm, whereby the water-soluble liquid resin r dries to form a water-soluble resin layer R. To speed up the drying of the water-soluble liquid resin, air may be sprayed from the spray nozzle 7 toward the center of the top surface of the wafer W. Alternatively, the wafer may be held on a table other than the first chuck table 1, separate from the cutting device, to perform the water-soluble resin filling step. The nozzle 18 and the wafer may be moved relatively horizontally along the cut groove Wa to fill the cut groove Wa with the water-soluble liquid resin r.

[0029] 5) Protective sheet attachment process: The protective sheet attachment process is a process for forming the work set WS1 shown in Figure 7 by attaching a sheet T1 to the front side of the wafer W whose cutting grooves Wa have been filled with a water-soluble resin layer R in the previous water-soluble resin filling process.

[0030] 7, the sheet T1 is attached to the entire surface of the wafer W (the lower surface in FIG. 7), thereby forming a work set WS1. The sheet T1 is an adhesive sheet having an adhesive layer on a base material, or a heat-sealable sheet.

[0031] The workpiece set WS1 formed as above and shown in FIG. 7 will be described below in terms of its use in the subsequent steps of a second holding step, a grinding step, and a water-soluble resin removing step.

[0032] 6)Second holding step: The second holding step is a step of holding the workpiece set WS1 shown in Fig. 7 on the second chuck table 20 of the grinding device as shown in Fig. 8. Here, the second chuck table 20 of the grinding device is a disk-shaped member, and a porous disk-shaped porous member 20A is incorporated in the upper central portion thereof. The upper surface of the porous member 20A forms the holding surface, and the porous member 20A is selectively connected to a suction source 23 such as a vacuum pump or an ejector via a communication passage 22 formed at the center of the second chuck table 20 and the rotation shaft 21.

[0033] In this second holding step, the work set WS1 is placed on the second chuck table 20, and the wafer W is suction-held with its backside facing up on the holding surface of the porous member 20A of the second chuck table 20. That is, when the porous member 20A is evacuated by the suction source 23 with the wafer W placed on the holding surface of the porous member 20A of the second chuck table 20 via the sheet T1, a negative pressure is generated in the porous member 20A, and the wafer W of the work set WS1 is suction-held on the holding surface of the porous member 20A via the sheet T1.

[0034] 7) Grinding process: As shown in Figure 9, the grinding process is a process in which the back surface (top surface in Figure 9) of the wafer W of the work set WS1 held on the second chuck table 20 of the grinding device in the previous second holding process is ground using the grinding wheel 33b of the grinding device to expose a cutting groove Wa on the back surface of the wafer W.

[0035] 9, a grinding unit 30 is disposed above the second chuck table 20, and a grinding wheel 33 is detachably attached to the underside of a disk-shaped mount 32 connected to the lower end of a rotatable vertical spindle 31 of the grinding unit 30. Here, the grinding wheel 33 is composed of a disk-shaped base 33a and a plurality of block-shaped grinding stones 33b attached in a circular ring shape to the underside of the base 33a.

[0036] The spindle 31 of the grinding unit 30 and the grinding wheel 33 attached to its lower end are rotated at a predetermined speed in the direction of the arrow by a spindle motor (not shown) and moved up and down by a Z-axis movement mechanism (elevating mechanism) (not shown). A plurality of injection nozzles 34 are vertically formed on the radially inner side of the grinding stone 33b of the base 33a of the grinding wheel 33, and these injection nozzles 34 are connected to a grinding water supply source 37 via a plurality of communication passages 35 formed in the mount 32 and a communication passage 36 formed in the axial center of the spindle 31. A motor 25, which serves as a rotation drive source, is connected to the rotation shaft 21 extending vertically downward from the second chuck table 20, as shown in FIG. 10.

[0037] 9 by a motor 25 shown in Fig. 10, the second chuck table 20 and the work set WS1 held thereon are rotated at a predetermined speed in the direction of the arrow in Fig. 9, and the grinding wheel 33 is rotated at a predetermined speed in the direction of the arrow (the same rotational direction as the second chuck table 20) by a spindle motor (not shown), and the grinding wheel 33 is lowered a predetermined amount (amount of grinding allowance) by a Z-axis movement mechanism (elevation mechanism) (not shown).The back surface of the wafer W (the upper surface in Fig. 9) is then uniformly ground by the rotating grinding stone 33b. Here, the grinding allowance of the back surface of the wafer W is set to a value that causes the lattice-shaped, bottomed cut grooves Wa formed in the wafer W to be exposed on the back surface of the wafer W, specifically, a value that causes the remaining portions W1 of the wafer W other than the cut grooves Wa (hatched portions in Fig. 9) to be completely removed by grinding, and the thickness of the wafer W after grinding to be equal to or less than the depth h of the cut grooves Wa (see Fig. 4).

[0038] When the back surface of the wafer W is being ground in this grinding process, grinding water is supplied from the grinding water supply source 37 through the communication passages 36, 35 and from the plurality of spray nozzles 34 to the contact portion (grinding portion) between the grinding wheel 33b and the wafer W, thereby cooling the contact portion (grinding portion) between the grinding wheel 33b and the wafer W to suppress a temperature rise and washing away grinding debris generated by grinding. Note that pure water is preferably used as the grinding water.

[0039] As a result of grinding the back surface of the wafer W in this grinding process, lattice-shaped, bottomed cutting grooves Wa are exposed on the back surface of the wafer W (top surface in Figure 10), as shown in Figure 10, and the wafer W is divided into multiple chips C.

[0040] 8) Water-soluble resin removal process: The water-soluble resin removal step is a step of removing a water-soluble resin layer R (see FIG. 9) remaining in the lattice-shaped cut grooves Wa of the wafer W, which have been exposed on the back surface by grinding in the preceding grinding step. That is, in this water-soluble resin removal step, as shown in FIG. 10, while the second chuck table 20 and the work set WS1 held thereon are rotated by a motor 25 around their axis at a predetermined speed in the direction of the arrow in the drawing, cleaning water supplied from a cleaning water supply source 26 disposed above the second chuck table 20 is sprayed from a spray nozzle 27 toward the center of the top surface of the wafer W.

[0041] Then, the cleaning water sprayed from the spray nozzle 27 onto the center of the top surface of the wafer W spreads uniformly toward the outer periphery of the wafer W by centrifugal force, and the water-soluble resin layer R (see FIG. 10) remaining in the cut groove Wa of the wafer W is dissolved and removed by the cleaning water. Then, the wafer W from which the water-soluble resin layer R has been removed from the cut groove Wa is dried by spraying air from an air supply source 28 disposed above the second chuck table 20 onto the top surface (back surface) of the wafer W from the spray nozzle 29. Note that pure water is preferably used as the cleaning water. Alternatively, the spray nozzles 27, 29 and the wafer W may be moved relatively along the cut groove Wa to dissolve and remove or dry the water-soluble resin layer R.

[0042] As described above, in the water-soluble resin removal process, when the water-soluble resin layer R remaining in the cut groove Wa of the wafer W is dissolved and removed by cleaning water, the wafer W is divided into multiple chips C, as shown in Figure 10.

[0043] As described above, according to the method for dividing a wafer W according to this embodiment, a lattice-shaped, bottomed cut groove (half-cut groove) Wa is formed on the surface of the wafer W (the surface on which the devices D are formed) in the cut groove forming step, and a water-soluble resin layer R is formed on the surface of the wafer W in the water-soluble resin filling step. The back surface of the wafer W is ground in the grinding step to expose the cut groove Wa. The water-soluble resin layer R filled in the exposed cut groove Wa is then dissolved and removed with cleaning water in the water-soluble resin removal step, thereby dividing the wafer W into multiple chips C. This allows a relatively small amount of the water-soluble resin layer R filled in the cut groove Wa to be dissolved and removed in a short time. As a result, the productivity of the chips C can be improved. Furthermore, in the cutting step, the cut groove Wa is filled with the water-soluble resin layer R, which prevents cutting debris from adhering to the side surfaces of the divided chips C.

[0044] Furthermore, in this embodiment, the cut grooves Wa formed in the wafer W in the cut groove forming step are cleaned in the cut groove cleaning step, so that adhesion of cutting debris to the cut grooves Wa can be prevented.

[0045] Furthermore, in this embodiment, the water-soluble resin layer R formed on the surface of the wafer W in the water-soluble resin filling process is dissolved and removed with cleaning water, thereby preventing abrasive grains or cutting chips from adhering to the sides of the divided chips C.

[0046] It should be noted that the present invention is not limited to the application of the above-described embodiments, and various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0047] 1: first chuck table, 1A: porous member, 2: suction source, 3: X-axis movement mechanism, 4: cleaning water supply source, 5: spray nozzle, 6: air supply source, 7: spray nozzle, 8: rotating shaft, 9: motor, 10: cutting unit, 11: cutting blade, 12: spindle, 13: Housing; 14, 15: Injection nozzle; 16: Cutting water supply source; 17: Liquid resin supply source; 18: nozzle, 20: second chuck table, 20A: porous member, 21: rotating shaft, 22: communication passage, 23: suction source, 25: motor, 26: cleaning water supply source, 27: Injection nozzle, 28: Air supply source, 29: Injection nozzle, 30: Grinding unit, 31: spindle, 32: mount, 33: grinding wheel, 33a: base, 33b: grinding wheel, 34: spray nozzle, 35, 36: communication passage, 37: grinding water supply source, C: Chip, D: Device, h: Depth of cutting groove, L1, L2: Street, R: Water-soluble resin layer, r: water-soluble liquid resin, T1: sheet, t: wafer thickness, W: wafer, W1: remaining part of wafer, Wa: cutting groove, WS1: work set

Claims

[Claim 1] A wafer dividing method for dividing a wafer having a surface divided by streets and having devices formed in each of the multiple regions along the streets to obtain multiple chips, comprising: a first holding step of holding the wafer with its front surface facing up on a first chuck table of the cutting device; a cutting groove forming step of cutting the surface of the wafer along the streets to a predetermined depth using a cutting blade of the cutting device to form cutting grooves; a water-soluble resin filling step of applying a water-soluble liquid resin from the front surface side of the wafer and drying the resin to fill the cut grooves with the water-soluble resin; a protective sheet attaching step of attaching a protective sheet to the surface of the wafer; a second holding step of holding the wafer with its back surface facing up on a second chuck table of a grinding device; a grinding step of grinding the back surface of the wafer held on the second chuck table with a grinding wheel to expose the cut grooves on the back surface of the wafer, thereby dividing the wafer into individual chips; a water-soluble resin removing step of spraying cleaning water onto the wafer divided into a plurality of chips to remove the water-soluble resin filled in the cut grooves; A wafer dividing method, characterized by dividing the wafer by sequentially carrying out the above steps.

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