JP7201459B2 - Wafer processing method - Google Patents

Description

The present invention relates to a wafer processing method.

A wafer having a plurality of devices formed on its front side is cut with a cutting blade along, for example, dividing lines (streets) to be divided into a plurality of device chips corresponding to respective devices. In order to fix the device chip to another substrate or the like, an adhesive layer for fixing may be provided on the back side of the device chip.

In the conventional processing method, a sheet-like adhesive material called a die attach film (hereinafter referred to as DAF) is attached to the back surface of the wafer as an adhesive layer, and the wafer and DAF are separated together to form a device chip with an adhesive layer. get Wafer division includes processing methods called so-called DBG (Dicing Before Grinding) and SDBG (Stealth Dicing Before Grinding). A processing method called DBG or SDBG is a processing method in which half-cut grooves or modified layers are formed along streets and a modified layer is formed by a laser beam, and then the rear surface of the wafer is ground to divide the wafer into individual device chips.

In the case of these processing methods, since the wafer is already divided into device chips before the DAF is attached, a separate step of dividing the DAF using a laser beam or the like is added. In the case of the processing method described above, since the DAF is attached to the wafer that has already been divided into device chips, the alignment of the device chips is disturbed, and the cutting position of the DAF is meandering. There was a problem that it took a long time.

Therefore, the applicant of the present invention devised a method of applying a liquid die-bonding resin that does not require division and is suitable for wafers after DBG and SDBG (see, for example, Patent Document 1).

JP 2017-041574 A

However, in the processing method disclosed in Patent Document 1, since the device chips are already divided, the liquid die-bonding resin enters the gaps between the device chips and adheres to the side surfaces of the device chips. There was still a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wafer processing method capable of suppressing adhesion of a die-bonding resin to the side surface of a device chip.

In order to solve the above-described problems and achieve the object, a wafer processing method of the present invention is a wafer processing method in which the surface of the wafer is partitioned by dividing lines and devices are formed in each of the partitioned regions. a wafer preparation step of preparing a wafer formed to a predetermined thickness and having a protective member attached to its surface; A die-bonding resin layer forming step of applying a resin to form a die-bonding resin layer having a desired thickness; a modified layer forming step of irradiating along the planned division line from the wafer to form a modified layer along the planned division line inside the wafer; and a wafer breaking step of breaking the wafer together with the die-bonding resin layer along the modified layer to form a device chip having the die-bonding resin layer.

In the wafer processing method, after the step of forming the die-bonding resin layer and before or after the step of forming the modified layer, the expanding tape is attached to the back surface of the wafer through the die-bonding resin layer. A bonding step may be provided, and in the wafer breaking step, the expanding tape may be expanded to break the wafer.

In the wafer processing method, in the modified layer forming step, the wafer may be irradiated with the laser beam from the expand tape side.

In the wafer processing method, in the wafer breaking step, the die-bonding resin layer may be cooled to promote breakage of the die-bonding resin.

ADVANTAGE OF THE INVENTION This invention produces the effect that it can suppress that the resin for die-bonding adheres to the side surface of a device chip.

FIG. 1 is a perspective view of a wafer to be processed by a wafer processing method according to Embodiment 1. FIG. FIG. 2 is a perspective view of a device chip manufactured by the wafer processing method according to the first embodiment. FIG. 3 is a flow chart showing the flow of the wafer processing method according to the first embodiment. 4 is a perspective view showing the wafer after the wafer preparation step of the wafer processing method shown in FIG. 3. FIG. FIG. 5 is a cross-sectional view schematically showing a step of forming a die-bonding resin layer in the wafer processing method shown in FIG. FIG. 6 is a cross-sectional view schematically showing a modified layer forming step of the wafer processing method shown in FIG. FIG. 7 is a cross-sectional view showing a state in which an expanding tape is attached to the rear surface of the wafer in the expanding tape attaching step of the wafer processing method shown in FIG. FIG. 8 is a cross-sectional view showing a state in which the BG tape is peeled off from the front surface side of the wafer in the expanding tape attaching step of the wafer processing method shown in FIG. FIG. 9 is a cross-sectional view schematically showing a state in which the wafer is held by the dividing device in the dividing step of the wafer processing method shown in FIG. FIG. 10 is a cross-sectional view schematically showing a state in which the wafer is divided into individual device chips in the dividing step of the wafer processing method shown in FIG. FIG. 11 is a flow chart showing the flow of the wafer processing method according to the second embodiment. FIG. 12 is a cross-sectional view schematically showing a modified layer forming step of the wafer processing method shown in FIG.

A form (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions, or changes in configuration can be made without departing from the gist of the present invention.

[Embodiment 1]
A wafer processing method according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a wafer to be processed by a wafer processing method according to Embodiment 1. FIG. FIG. 2 is a perspective view of a device chip manufactured by the wafer processing method according to the first embodiment. FIG. 3 is a flow chart showing the flow of the wafer processing method according to the first embodiment.

The wafer processing method according to the first embodiment is a method for manufacturing device chips 2 shown in FIG. 2 from the wafer 1 shown in FIG. A wafer 1 to be processed by the wafer processing method is a disk-shaped semiconductor wafer or an optical device wafer having a substrate 3 made of silicon, sapphire, gallium arsenide, or the like.

As shown in FIG. 1, the surface 4 of the substrate 3 is partitioned by division lines 5 set in a grid pattern, and the devices 6 are formed in each region partitioned by the division lines 5. As shown in FIG. The device 6 is, for example, an integrated circuit such as an IC (Integrated Circuit) or LSI (Large Scale Integration), a CCD (Charge Coupled Device), or an image sensor such as a CMOS (Complementary Metal Oxide Semiconductor).

In Embodiment 1, the wafer 1 is divided into individual devices 6 along dividing lines 5 to be singulated into device chips 2 shown in FIG. The device chip 2 includes a portion of the substrate 3, a device 6 on the substrate 3, and a die-bonding resin layer 8 laminated on the back surface 7 side of the substrate 3. 9 is formed. The die-bonding resin layer 8 is for fixing the device chip 2 to another device chip 2 or another substrate. The modified layer 9 means a region whose density, refractive index, mechanical strength and other physical properties are different from those of its surroundings. Examples include a rate change area and an area in which these areas are mixed. Moreover, the modified layer 9 has lower mechanical strength and the like than other portions of the wafer 1 .

Next, a method for processing a wafer according to Embodiment 1 will be described. In the wafer processing method according to the first embodiment, a die bonding resin layer 8 is formed on a wafer 1 whose back surface 7 has been ground and polished to a predetermined thickness, and the wafer 1 is divided along a line to be divided. It is a method of manufacturing device chips 2 by dividing into individual devices 6 along lines 5 . As shown in FIG. 3, the wafer processing method includes a wafer preparation step ST1, a die-bonding resin layer forming step ST2, a modified layer forming step ST3, an expanding tape attaching step ST4, and a wafer breaking step ST5. Prepare.

(wafer preparation step)
4 is a perspective view showing the wafer after the wafer preparation step of the wafer processing method shown in FIG. 3. FIG. The wafer preparation step ST1 is a step of preparing the wafer 1 which is formed to a predetermined thickness 11 by grinding and polishing and has a BG (Back Grind) tape, which is a protective member, adhered to the front surface 4 side of the substrate 3 . be. In Embodiment 1, the BG tape 20 is formed in the same disc shape as the wafer 1 .

In the first embodiment, in the wafer preparation step ST1, as shown in FIG. 4, a well-known mounter adheres a BG tape 20 having the same diameter as the wafer 1 to the front surface 4 side of the substrate 3, and grinds the back surface 7 of the wafer 1. To prevent the device 6 from being damaged when After the wafer preparation step ST1, the wafer processing method proceeds to a die-bonding resin layer formation step ST2.

(Die-bonding resin layer forming step)
FIG. 5 is a cross-sectional view schematically showing a step of forming a die-bonding resin layer in the wafer processing method shown in FIG. In the die-bonding resin layer forming step ST2, a liquid die-bonding resin 8-1 is applied to the back surface 7 of the substrate 3 of the wafer 1 on the side opposite to the front surface 4 of the substrate 3 to which the BG tape 20 is adhered. This is the step of forming a thick die-bonding resin layer 8 .

In the die-bonding resin layer forming step ST2, the operator places the front surface 4 side of the substrate 3 of the wafer 1 via the BG tape 20 on the holding surface 32 of the holding table 31 of the resin laying device 30, and the resin laying device 30 The surface 4 of the substrate 3 of the wafer 1 is held by suction on the holding surface 32 of the holding table 31 via the BG tape 20 . In the die-bonding resin layer forming step ST2, the resin laying device 30 supplies the liquid die-bonding resin 8-1 and high-pressure air from the coating nozzle 33, which moves along the holding surface 32 while rotating the holding table 31 about its axis. Mix and spray.

In Embodiment 1, as the liquid die-bonding resin 8-1, an ultraviolet curable adhesive that hardens when irradiated with ultraviolet rays as an external stimulus is used. As the UV curable adhesive, for example, Honghow Specialty Chemicals Inc. product name "HP20VL" or "ST20VL" manufactured by In the present invention, the liquid die-bonding resin 8-1 is a silver-filled epoxy resin adhesive that is solidified by applying a predetermined heat as an external stimulus, such as "Ablebond 8200c" (trade name) manufactured by Ablestik Laboratories. is available.

In the die-bonding resin layer forming step ST2, the holding table 31 is rotated about its axis, and the mixture of the liquid die-bonding resin 8-1 and the high-pressure gas is sprayed from the coating nozzle 33 while the coating nozzle 33 is set in advance. After moving along the holding surface 32 a predetermined number of times, the coating nozzle 33 is returned to the standby state in which it is retracted from above the wafer 1, the supply of the liquid die bonding resin 8-1 and the supply of high-pressure air are stopped, and the holding table 31 is stopped. also stop rotating. Further, in Embodiment 1, the thickness of the thin film layer formed by the liquid die-bonding resin 8-1 is limited by limiting one coating process to a predetermined number of times as described above without spraying a large amount at once. is 3 μm or more and 7 μm or less.

The liquid die-bonding resin 8-1 sprayed onto the back surface 7 of the substrate 3 of the wafer 1 is stabilized and slightly hardened (for example, about 30 seconds). A similar process of applying a liquid die-bonding resin 8-1 is performed to further form a thin film layer of the liquid die-bonding resin 8-1. In the present invention, the number of coating processes for forming the thin film layer may be such that the final thickness of the liquid die-bonding resin 8-1 is 10 μm or more and 50 μm or less.

In the first embodiment, in the die-bonding resin layer forming step ST2, ultraviolet light is emitted from the ultraviolet irradiation means as a means for applying an external stimulus to the back surface 7 side of the substrate 3 coated with the liquid die-bonding resin 8-1. A die-bonding resin layer 8 is formed on the back surface 7 side of the substrate 3 of the wafer 1 by irradiating and curing the resin. In the present invention, when a thermosetting resin is used as the liquid die-bonding resin 8-1, the liquid die-bonding resin 8-1 is cured by heating with a heater or the like instead of the ultraviolet irradiation. However, a die-bonding resin layer 8 may be formed on the rear surface 7 of the substrate 3 of the wafer 1 . The wafer processing method advances to modified layer forming step ST3 after die bonding resin layer forming step ST2.

(Modified layer forming step)
FIG. 6 is a cross-sectional view schematically showing a modified layer forming step of the wafer processing method shown in FIG. In the modified layer forming step ST3, a laser beam 44 having a wavelength (1064 nm in the embodiment) that is transparent to the wafer 1 and the die-bonding resin layer 8 is applied to the substrate 3 of the wafer 1 through the die-bonding resin layer 8. In this step, a modified layer 9 is formed inside the substrate 3 of the wafer 1 along the dividing lines 5 by irradiating the light from the rear surface 7 side of the wafer 1 along the dividing lines 5 .

In the modified layer forming step ST3, the operator places the surface 4 side of the substrate 3 of the wafer 1 on the holding surface 42 of the chuck table 41 of the laser processing device 40 via the BG tape 20, and the laser processing device 40 moves the chuck. The surface 4 of the substrate 3 of the wafer 1 is held by suction on the holding surface 42 of the table 41 via the BG tape 20 .

In the modified layer forming step ST3, the laser beam processing device 40 relatively moves the chuck table 41 and the laser beam irradiation unit 43 along the planned division line 5 while moving the laser beam irradiation unit 43 as shown in FIG. A condensing point 44-1 is set inside the substrate 3, and a pulsed laser beam 44 is irradiated along the dividing line 5. As shown in FIG. In Embodiment 1, in the modified layer forming step ST3, the laser processing apparatus 40 moves the laser beam irradiation unit 43 from the position indicated by the dotted line in FIG. A laser beam 44 is irradiated while moving the chuck table 41 toward the position indicated by the solid line.

In the modified layer forming step ST3, since the laser beam 44 has a wavelength that is transparent to the wafer 1, as shown in FIG. Form.

In the modified layer forming step ST3, once the modified layer 9 is formed inside the substrate 3 along all the planned division lines 5, the irradiation of the laser beam 44, the suction holding of the chuck table 41 is released, and the expanding tape is adhered. Go to step ST4.

(Expansion tape attachment step)
FIG. 7 is a cross-sectional view showing a state in which an expanding tape is attached to the rear surface of the wafer in the expanding tape attaching step of the wafer processing method shown in FIG. FIG. 8 is a cross-sectional view showing a state in which the BG tape is peeled off from the front surface side of the wafer in the expanding tape attaching step of the wafer processing method shown in FIG.

The expanding tape attaching step ST4 is performed after the die-bonding resin layer forming step ST2 and after the modified layer forming step ST3. This is the step of attaching the expanding tape 12 . The expanding tape 12 has a base layer made of a synthetic resin and an adhesive layer laminated on the base layer, and has higher elasticity than the cured die-bonding resin layer 8 . Further, in Embodiment 1, the expandable tape 12 is formed in a disc shape having a larger diameter than the outer diameter of the wafer 1 .

In the expanding tape attaching step ST4, the mounter 50 holds the surface 4 side of the substrate 3 of the wafer 1 via the BG tape 20 and the ring-shaped annular frame 13 whose inner diameter is larger than the outer diameter of the wafer 1. It is held on the holding surface 52 of the table 51 . The mounter 50 holds the wafer 1 and the annular frame 13 on the holding surface 52 of the holding table 51 at a position where they are coaxial. In the expanding tape attaching step ST4, the mounter 50 feeds the expanding tape 12 to the annular frame 13 and the back surface 7 of the substrate 3 of the wafer 1, and moves along the back surface 7 of the wafer 1, as shown in FIG. The expanding tape 12 is pressed against the annular frame 13 and the rear surface 7 side of the wafer 1 by the roller 53 to adhere them in close contact.

In the expanding tape attaching step ST4, the mounter 50 attaches the expanding tape 12 to the annular frame 13 and the rear surface 7 of the wafer 1, and then attaches the BG tape 20 to the surface of the substrate 3 of the wafer 1 as shown in FIG. Remove from 4 sides. The wafer processing method advances to the wafer breaking step ST5 after the expanding tape attaching step ST4.

(Wafer breaking step)
FIG. 9 is a cross-sectional view schematically showing a state in which the wafer is held by the dividing device in the dividing step of the wafer processing method shown in FIG. FIG. 10 is a cross-sectional view schematically showing a state in which the wafer is divided into individual device chips in the dividing step of the wafer processing method shown in FIG.

In the wafer breaking step ST5, the wafer 1 on which the modified layer 9 is formed is expanded in the plane direction, and the wafer 1 is broken along the modified layer 9 together with the die-bonding resin layer 8 to form a device having the die-bonding resin layer 8. This is the step of forming the chip 2 . In the wafer breaking step ST5, the breaking device 60 holds the annular frame 13 between the clamping portions 61 and fixes the wafer 1 with the front surface 4 side of the substrate 3 facing upward. At this time, as shown in FIG. 9, the breaking device 60 keeps the cylindrical expanding drum 62 in contact with the area between the wafer 1 and the annular frame 13 of the expanding tape 12 . The expansion drum 62 has an inner diameter and an outer diameter that are smaller than the inner diameter of the annular frame 13 and larger than the outer diameter of the wafer 1 , and is arranged at a position coaxial with the annular frame 13 fixed by the clamp part 61 .

Further, in the first embodiment, in the wafer breaking step ST5, the cooling plate 63 is kept in contact with the back surface 7 of the substrate 3 of the wafer 1 via the die bonding resin layer 8 and the expanding tape 12, and the clamping part 61 and the expansion drum 62 and cooling plate 63 are housed in a cooling chamber (not shown). In the present invention, the cooling plate 63 may not be provided, and the clamping part 61 and the expansion drum 62 may not be housed in a cooling chamber (not shown).

In the first embodiment, in the wafer breaking step ST5, the cooling plate 63 cools the die-bonding resin layer 8 via the expanding tape 12, and cools the inside of the cooling chamber to cool the die-bonding resin layer 8. In the wafer breaking step ST5, the breaking device 60 lowers the clamp part 61 as shown in FIG. Then, since the expanding tape 12 is in contact with the expansion drum 62, the expanding tape 12 is expanded in the planar direction. In the wafer breaking step ST5, a radial tensile force acts on the expanding tape 12 as a result of the expansion.

When a tensile force acts radially on the expanding tape 12 attached to the back surface 207 side of the substrate 3 of the wafer 1, the wafer 1 is reformed along the split lines 5 in the reformed layer forming step ST3. Since the layer 9 is formed, each device 6 is divided with the modified layer 9 as a fracture starting point, and each device chip 2 is singulated. Since the die-bonding resin layer 8 is broken along the modified layer 9 , the die-bonding resin layer 8 is also broken along the modified layer 9 .

In the first embodiment, the clamping part 61 is lowered to expand the expanding tape 12 in the wafer breaking step ST5. In short, the expansion drum 62 should be raised relative to the clamping portion 61 and the clamping portion 61 should be lowered relative to the expansion drum 62 . Thus, in the first embodiment, the expanding tape 12 is expanded to break the wafer 1 in the wafer breaking step ST5.

Further, in Embodiment 1, the die-bonding resin layer 8 is cooled to promote breakage of the die-bonding resin layer 8 . The wafer processing method ends when the wafer 1 is divided along the dividing line 5 .

As described above, in the wafer processing method according to the first embodiment, after the liquid die bonding resin 8-1 is applied in the die bonding resin layer forming step ST2, the laser beam 44 is applied to the die bonding resin in the modified layer forming step ST3. A condensing point 44 - 1 is set inside the substrate 3 through the layer 8 to form a modified layer 9 inside the substrate 3 of the wafer 1 . For this reason, the wafer processing method can suppress the lengthening of the required time such as alignment when dividing the DAF adhered after division into the device chips 2 by laser processing. In addition, in the wafer processing method, the wafer 1 is broken after the die-bonding resin 8-1 is cured. It also has the effect of being able to

Furthermore, in the wafer processing method according to the first embodiment, compared to dividing the wafer 1 into the device chips 2 by cutting using a cutting blade, the modified layer 9 is formed inside the substrate 3 by irradiating the laser beam 44 . can be narrowed, and the high-speed machining can shorten the machining time.

Further, in the wafer processing method according to the first embodiment, even if the back surface 7 of the substrate 3 of the wafer 1 has unevenness, the liquid die bonding resin 8-1 is applied to the back surface 7. The surface of the die-bonding resin layer 8 formed by curing -1 is flattened. As a result, the wafer processing method can suppress irregular reflection of the laser beam 44 due to the unevenness of the back surface 7 of the wafer 1 and form the modified layer 9 .

[Embodiment 2]
A wafer processing method according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 11 is a flow chart showing the flow of the wafer processing method according to the second embodiment. FIG. 12 is a cross-sectional view schematically showing a modified layer forming step of the wafer processing method shown in FIG. In addition, FIG.11 and FIG.12 attach|subjects the same code|symbol to the same part as Embodiment 1, and abbreviate|omits description.

The wafer processing method according to the second embodiment includes, as shown in FIG. 11, a wafer preparation step ST1, a die-bonding resin layer forming step ST2, an expanding tape attaching step ST4-2, and a modified layer forming step ST3-. 2 and a wafer breaking step ST5.

The expanding tape attaching step ST4-2 is performed after the die-bonding resin layer forming step ST2 and before the modified layer forming step ST3-2. It is a step of sticking the expanding tape 12 on the . The expanding tape attaching step ST4-2 is the expanding tape attaching step according to Embodiment 1, except that the expanding tape 12 is attached to the back surface 7 side of the substrate 3 of the wafer 1 before the modified layer 9 is formed. Same as ST4. In the second embodiment, the wafer processing method advances to the modified layer forming step ST3-2 after the step ST4-2 of attaching the expanding tape.

In the modified layer forming step ST3-2, similarly to the modified layer forming step ST3 according to the first embodiment, a laser beam 44 having a wavelength that is transparent to the wafer 1 is applied to the expanding tape 12 and the die bonding resin layer 8. This is a step of irradiating the back surface 7 of the substrate 3 of the wafer 1 along the dividing line 5 to form the modified layer 9 along the dividing line 5 inside the substrate 3 of the wafer 1 . Further, in the modified layer forming step ST3-2, as shown in FIG. 12, the laser processing device 40 sucks and holds the surface 4 of the substrate 3 of the wafer 1 on the holding surface 42 of the chuck table 41 via the porous sheet 14. Then, while relatively moving the chuck table 41 and the laser beam irradiation unit 43 along the dividing line 5, the light condensing point 44-1 of the laser beam irradiation unit 43 is set inside the substrate 3, and a pulse-like beam is generated. A laser beam 44 is irradiated along the planned division line 5 .

As described above, in Embodiment 2, in the modified layer forming step ST3-2, the wafer 1 is irradiated with the laser beam 44 from the expanding tape 12 side, and the modified layer 9 is formed inside the substrate 3 along the dividing line 5. to form In the modified layer forming step ST3-2, when the modified layer 9 is formed inside the substrate 3 along all the dividing lines 5, the irradiation of the laser beam 21 and the suction holding of the chuck table 41 are released to break the wafer. Go to step ST5.

In the wafer processing method according to the second embodiment, after the liquid die bonding resin 8-1 is applied in the die bonding resin layer forming step ST2, the laser beam 44 is applied to the expanding tape 12 and the die bonding resin layer 8 in the modified layer forming step ST3. A condensing point 44 - 1 is set inside the substrate 3 through the wafer 1 to form a modified layer 9 inside the substrate 3 of the wafer 1 . For this reason, the wafer processing method can suppress the lengthening of the required time such as alignment when dividing the DAF adhered after division into the device chips 2 by laser processing. The wafer processing method also has the effect of suppressing adhesion of the liquid die-bonding resin 8-1 to the side surfaces 10 of the device chips 2. FIG.

In the wafer processing method according to the second embodiment, unlike the first embodiment, the wafer 1 is replaced with the expanding tape 12 before the modified layer 9 is formed. There is an effect that there is no risk of chipping due to rubbing.

It should be noted that the present invention is not limited to the above embodiments. That is, various modifications can be made without departing from the gist of the present invention.

REFERENCE SIGNS LIST 1 wafer 2 device chip 4 front surface 5 division line 6 device 7 back surface 8 die bonding resin layer 8-1 liquid die bonding resin 9 modified layer 11 predetermined thickness 12 expanding tape 20 BG tape (protective member)
44 Laser beam ST1 Wafer preparation step ST2 Die bonding resin layer forming step ST3, ST3-2 Modified layer forming step ST4, ST4-2 Expanding tape attaching step ST5 Wafer breaking step

Claims (4)

A wafer processing method in which the surface of the wafer is partitioned by dividing lines and devices are formed in each of the partitioned regions,
a wafer preparation step of preparing a wafer having a predetermined thickness and having a protective member attached to the surface thereof;
A die-bonding resin layer forming step of applying a liquid die-bonding resin to the back surface of the wafer opposite to the surface to which the protective member is attached to form a die-bonding resin layer having a desired thickness;
A laser beam having a wavelength that is transparent to the wafer is irradiated from the back side of the wafer through the die-bonding resin layer along the planned division line, and the inside of the wafer is reformed along the planned division line. a modified layer forming step of forming a modified layer;
a wafer breaking step of expanding the wafer on which the modified layer is formed in the planar direction, breaking the wafer along with the die bonding resin layer along the modified layer, and forming a device chip provided with the die bonding resin layer; A method of processing a wafer comprising: After the die-bonding resin layer forming step and before or after the modified layer forming step, an expanding tape attaching step of attaching an expanding tape to the back side of the wafer via the die-bonding resin layer,
2. The method of processing a wafer according to claim 1, wherein said wafer breaking step expands said expandable tape to break said wafer. 3. The method of processing a wafer according to claim 2, wherein in the modified layer forming step, the wafer is irradiated with the laser beam from the expand tape side. 4. The wafer processing method according to any one of claims 1 to 3, wherein in the wafer breaking step, the die bonding resin layer is cooled to promote breaking of the die bonding resin.

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