JP2018206795A - Wafer processing method - Google Patents

Abstract

To provide a wafer processing method capable of suppressing damage to a device due to laser beams and easily forming a device chip in which a die bonding resin is disposed on a rear surface of a wafer.SOLUTION: A wafer processing method comprises: a grinding step of grinding a rear surface side of the wafer in which a protective member is stuck to a surface of the wafer; a laser processing step of forming a modified layer and a crack extending toward the surface of the wafer from the modified layer by irradiating the wafer with laser beams from the rear surface side of the wafer along division schedule lines; a groove forming step of removing the modified layer and forming a groove by cutting a cutting blade into the wafer along the modified layer; a die bonding resin disposing step of supplying a liquid die bonding resin to each of the regions partitioned by the groove on the rear surface of the wafer; a replacing step of peeling the protective member after sticking an expand tape to the rear surface of the wafer; and a dividing step of dividing the wafer into individual chips by expanding the expand tape in a radial direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a wafer processing method for dividing a wafer along a planned division line.

  A plurality of division lines (streets) arranged in a lattice pattern are set on the surface of the wafer. A device using a semiconductor is formed in each region of the surface defined by the division lines. When the wafer is divided along the division line, individual device chips are formed. The formed device chip is mounted on various electronic devices.

  In recent years, electronic devices on which device chips are mounted tend to be downsized and thinned, and accordingly, there is an increasing demand for downsizing and thinning of device chips. In addition, attempts have been made to increase the number of devices that can be formed on a single wafer by reducing the width of the division line, thereby reducing the manufacturing cost of the device chip.

  A thin device chip is manufactured by grinding and thinning the wafer from the back side, and then dividing the wafer along the division line. The wafer is divided by, for example, cutting with an annular cutting blade or ablation processing by laser beam irradiation. However, when the wafer is divided by these methods, chipping may occur at the end of the device chip formed by the division or the side surface of the device chip may be distorted. Is easy to make.

  Therefore, a thinned device chip is manufactured by a process called dicing before grinding (DBG). In the process, a groove is formed on the front surface side of the wafer along the division line, and then the wafer is ground from the back surface side to remove the bottom of the groove, thereby dividing the wafer to form device chips. .

  In recent years, a process called SDBG (Stealth Dicing Before Grinding) has attracted attention among the previous dicing processes. In SDBG, a modified layer is formed inside the wafer along the planned dividing line, and a crack reaching the surface of the wafer is formed from the modified layer as a starting point (see Patent Document 1). When the laser beam is irradiated to the wafer along the planned dividing line in a state where a laser beam having transparency to the wafer is condensed inside the wafer, the modified layer is formed by multiphoton absorption. The

  Since cracks formed along the planned division line in SDBG are narrower than grooves formed by cutting with a cutting blade or ablation with a laser beam, it is possible to set the planned division line narrower than in these cases. it can. Further, rather than forming a groove in the wafer by cutting with a cutting blade or ablation processing with a laser beam, chipping is less likely to occur in the wafer by SDBG, and the bending strength of the device chip to be formed becomes higher.

  Incidentally, a die bonding resin (DAF: Die Attach Film) may be provided on the back surface of the manufactured device chip. The resin for die bonding functions as an adhesive when the device chip is mounted on a mounting target (see Patent Document 2).

JP 2009-289773 A JP 2006-207936 A

  In DBG or SDBG, the back side of the wafer is ground to thin the wafer to form device chips, and then a film-like die-bonding resin is attached to the back side of the wafer, and a laser beam is applied between adjacent device chips. Irradiation causes the film-like die bonding resin to break for each device chip. However, since the distance between the device chips is narrow when the device chips are formed, there is a problem that it is not easy to break the die bonding resin separated according to each device chip.

  Also, in SDBG, in order to properly extend a crack to a predetermined position on the front surface side of the wafer, a laser beam is irradiated from the back surface side of the thick wafer before being thinned, and is close to the front surface side of the wafer. A modified layer must be formed at a depth. Therefore, a predetermined output is required for the laser beam irradiated for forming the modified layer, and there are cases where multiple laser beam irradiations are required.

  Part of the irradiated laser beam contributes to the formation of the modified layer by multiphoton absorption, while the other part passes through the condensing point and passes through the wafer. Then, the leakage light or splash of the laser beam that has passed through the wafer reaches the device. For this reason, the device may be damaged when the wafer is irradiated with a high-power laser beam or a plurality of laser beams.

  The present invention has been made in view of such problems, and the object of the present invention is to form a modified layer with a low-power laser beam or a laser beam with a small number of scans, thereby suppressing leakage and splash of the laser beam. Thus, it is an object of the present invention to provide a wafer processing method capable of suppressing device damage. Another object of the present invention is to provide a wafer processing method capable of easily forming a resin for die bonding on the back surface of a device chip to be formed.

  According to an aspect of the present invention, there is provided a wafer processing method in which division lines are set in a lattice pattern on the surface, and a device is formed in each of a plurality of regions partitioned by the division lines. A protective member adhering step for adhering a protective member to the surface of the wafer, a grinding step for thinning the wafer by grinding the back side of the wafer with the protective member adhering to the surface, and the wafer By irradiating a laser beam having a wavelength having transparency with respect to a predetermined depth position of the wafer along the division line from the thinned back surface side of the wafer, the modified layer and the modified A laser processing step for forming a crack extending from the layer toward the surface inside the wafer, and a cutting blade from the back surface of the wafer along the modified layer to a depth not reaching the surface. A groove forming step for removing the modified layer and forming a groove along the planned dividing line, and a liquid in each region defined by the groove on the back surface of the wafer. Supplying a die bonding resin, solidifying the liquid die bonding resin, and affixing an expanded tape to the back surface of the wafer via the die bonding resin; A reattachment step for peeling off the protective member, and a device chip in which the expand tape is expanded in the radial direction to divide the wafer into individual device chips starting from the crack, and a die bonding resin is disposed on the back surface And a dividing step of forming a wafer. A method of processing a wafer is provided.

  In one embodiment of the present invention, the die bonding resin disposing step includes: an application step in which the liquid die bonding resin is sprayed and applied to the back surface of the wafer; and the applied liquid liquid A solidifying step of solidifying the die bonding resin to form a thin film layer, the die bonding resin having the thin film layer laminated by alternately performing the coating step and the solidifying step a plurality of times. May be formed.

  In the wafer processing method according to one embodiment of the present invention, a protective member is attached to the front surface of the wafer and the back surface is ground to thin the wafer. Thereafter, the wafer is irradiated with a laser beam having a wavelength having transparency from the back side of the wafer to form a modified layer inside the wafer along the planned dividing line, and from the modified layer to the surface The crack which extends is formed.

  In the conventional SDBG process, a thick wafer before grinding the wafer is irradiated with a laser beam from the back surface side to form a modified layer, so that the distance from the back surface to the condensing position of the laser beam is relatively long. Therefore, it has been necessary to irradiate a high-power laser beam or to form a plurality of modified layers by scanning the laser beam a plurality of times.

  On the other hand, in the wafer processing method according to one embodiment of the present invention, the wafer is first ground and thinned from the back surface side, so the distance from the back surface of the wafer to the laser beam focusing position is relatively short. Thus, the output of the laser beam can be made relatively small. Therefore, damage to the device due to leakage or splash of the laser beam can be suppressed.

  Further, if the modified layer remains on the device chip, the bending strength of the device chip is lowered, and thus the modified layer is removed. In the wafer processing method according to one aspect of the present invention, the modified layer is removed by cutting a cutting blade into the wafer along the modified layer. At this time, the cutting blade is cut from the back surface side to a depth not reaching the surface.

  Since the wafer is divided into individual device chips by cracks extending to the surface side, the width of the line to be divided is set small, but the cutting blade should be cut at a depth that does not reach the surface side. In other words, the cutting blade does not damage the device.

  When the modified layer is removed by the cutting blade, a groove is formed on the back surface side of the wafer along the division line. Then, it becomes easy to form the die bonding resin (DAF) divided for each device chip on the back side of the wafer.

  That is, for example, a predetermined amount of the liquid die-bonding resin is supplied to the back side of the wafer by a method such as spraying a liquid die-bonding resin in the form of a mist to solidify it. Since the back surface side of the wafer is partitioned into regions for each device chip by the groove, a die bonding resin divided for each device chip can be formed on the back surface.

  At this time, the die bonding resin may be slightly connected between the device chips. However, when the expanded tape is attached to the back side of the wafer, the protective member is peeled off from the front side, and the expanded tape is expanded in the radial direction, the wafer is divided and connected to individual device chips. The resin for die bonding can also be divided. As described above, individual device chips in which the die bonding resin is disposed on the back surface side can be manufactured.

  According to the present invention, there is provided a wafer processing method in which a modified layer can be formed with a low-power laser beam or a laser beam with a small number of scans, and device damage can be suppressed by suppressing laser beam leakage and splash. In addition, a wafer processing method is provided in which a die bonding resin can be easily formed on the back surface of the device chip to be formed.

FIG. 1A is a perspective view schematically showing the front side of the wafer, and FIG. 1B is a perspective view schematically showing the back side of the wafer having a protective member attached to the front side. is there. It is a side view which shows a grinding step typically. FIG. 3A is a cross-sectional view schematically showing the laser processing step, and FIG. 3B is a cross-sectional view schematically showing the groove forming step. FIG. 4A is a cross-sectional view schematically showing the application step, FIG. 4B is a cross-sectional view schematically showing the solidification step, and FIG. 4C is an application performed again. It is sectional drawing which shows a step. FIG. 5A is a cross-sectional view schematically showing the re-covering step, and FIG. 5B is a cross-sectional view schematically showing the wafer with the expanded tape attached to the back surface. FIG. 6A is a cross-sectional view schematically showing the wafer before expanding the expanded tape, and FIG. 6B is a cross-sectional view schematically showing the dividing step.

  First, a wafer 1 that is a workpiece of the processing method according to the present embodiment will be described with reference to FIG. FIG. 1A is a perspective view schematically showing the wafer. The wafer 1 is a substrate made of, for example, silicon, SiC (silicon carbide), or another semiconductor material, or a material such as sapphire, glass, or quartz.

  The surface 1a of the wafer 1 is divided into a plurality of regions by a plurality of division lines (streets) 3 arranged in a lattice pattern, and each region divided by the plurality of division lines 3 is a device such as an IC. 5 is formed. Finally, the wafer 1 is thinned and divided along the division lines 3 to form individual device chips.

  Hereinafter, a wafer processing method according to the present embodiment will be described. First, a protection member attaching step for attaching the protection member 7 to the surface 1a of the wafer 1 is performed. FIG. 1B is a perspective view schematically showing the back surface 1b side of the wafer 1 having the protective member 7 attached to the front surface 1a side.

  The protective member 7 protects the surface 1a side of the wafer 1 from an impact applied during each step or transfer while the wafer processing method according to this embodiment is being performed, and the device 5 is damaged. It has a function to prevent.

  The protective member 7 has a flexible film-like base material and a glue layer (adhesive layer) formed on one surface of the base material. For example, PO (polyolefin), PET (polyethylene terephthalate), polyvinyl chloride, polystyrene or the like is used for the base material. For the glue layer (adhesive layer), for example, silicone rubber, acrylic material, epoxy material or the like is used.

  Next, a grinding step for thinning the wafer 1 by grinding the back surface 1b side of the wafer 1 is performed. FIG. 2 is a cross-sectional view schematically illustrating the grinding step. The grinding step is performed by the grinding apparatus 2 shown in FIG.

  The grinding apparatus 2 includes a chuck table 4 that holds the wafer 1 by suction. The chuck table 4 has a suction passage (not shown) having one end connected to a suction source (not shown) inside, and the other end of the suction passage forms a holding surface 4 a on the chuck table 4. It leads to a member (not shown). The chuck table 4 sucks and holds the wafer 1 by applying a negative pressure generated by the suction source to the workpiece 1 placed on the holding surface 4a through the porous member. Further, the chuck table 4 can rotate around an axis substantially perpendicular to the holding surface 4a.

  A grinding unit 6 is disposed above the chuck table 4. The grinding unit 6 has a spindle 8 that is rotated in the extending direction, and a grinding wheel 10 is fixed to the lower end of the spindle 8. A grinding wheel 12 for grinding the wafer 1 sucked and held by the chuck table 4 is mounted on the lower surface of the grinding wheel 10. The grinding unit 6 is supported by a machining feed unit (not shown), and the grinding unit 6 can be moved in the vertical direction by the machining feed unit.

  In the grinding step, first, the wafer 1 having the protective member 7 attached to the surface 1 a is placed on the holding surface 4 a of the chuck table 4. At this time, the wafer 1 is placed on the holding surface 4a through the protective member 7 attached to the surface 1a with the surface 1a side of the wafer 1 facing downward. Next, the suction source is operated to apply a negative pressure to the wafer 1 through the porous member, so that the chuck table 4 sucks and holds the wafer 1. Then, the back surface 1b of the wafer 1 is exposed upward.

  Next, the chuck table 4 is rotated around an axis substantially perpendicular to the holding surface 4a, and the spindle 8 of the grinding unit 6 is rotated. Then, the processing feed unit is operated while the grinding wheel 10 is rotated, and the grinding wheel 10 is processed and sent downward. When the grinding wheel 12 contacts the back surface 1b of the wafer 1, grinding of the wafer 1 starts. When the grinding wheel 10 is processed and fed so that the wafer 1 has a predetermined thickness, the wafer 1 is thinned.

  When the grinding step is performed, the wafer 1 is thinned to a predetermined thickness. The predetermined thickness is set to the finished thickness of the device chip formed by the wafer processing method according to the present embodiment. The finished thickness is, for example, 20 μm to 200 μm.

  Next, a laser processing step is performed. In the laser processing step, a laser beam having a wavelength that is transparent to the wafer 1 is irradiated from the back surface 1 b side of the wafer 1 to the predetermined depth position of the wafer 1 along the division line 3. FIG. 3A is a cross-sectional view schematically showing a laser processing step.

  In the laser processing step, a laser processing apparatus 14 shown in FIG. 3A is used. The laser processing apparatus 14 includes a chuck table 16 that sucks and holds the wafer 1. The chuck table 16 has the same configuration as the chuck table 4 provided in the above-described grinding apparatus 2.

The laser processing apparatus 14 includes a processing head 18 that oscillates a laser beam above the chuck table 16. The processing head 6 has a function of oscillating a pulse laser beam having a wavelength that is transmissive to the wafer 1 and condensing it to a predetermined depth inside the wafer 1, and the predetermined depth by multiphoton absorption. Then, a modified layer 9 is formed, and a crack 11 extending from the modified layer 9 to the surface 1a of the wafer 1 is generated. As the laser beam, for example, a laser beam oscillated using Nd: YVO ₄ or Nd: YAG as a medium is used.

  The laser machining apparatus 14 can move the chuck table 16 in the machining feed direction of the laser machining apparatus 14 by a machining feed means (machining feed mechanism, not shown) powered by a pulse motor or the like. At the time of laser processing of the wafer 1, the chuck table 16 is sent in the processing feed direction, and the wafer 1 is processed and sent. Further, the chuck table 16 can be rotated around an axis substantially perpendicular to the holding surface 16a. When the chuck table 16 is rotated, the processing feed direction of the wafer 1 can be changed.

  Further, the laser processing device 14 can move the chuck table 16 in the indexing and feeding direction (not shown) of the laser processing device 14 by an index feeding means (index feeding mechanism, not shown) powered by a pulse motor or the like.

  In the laser processing step, first, similarly to the grinding step, the wafer 1 is sucked and held on the chuck table 16 to expose the back surface 1b of the wafer 1 upward. Next, the relative positions of the chuck table 16 and the processing head 18 are adjusted so that the modified layer 9 can be formed inside the wafer 1 from one end to the other end of the planned division line 3 along the planned division line 3.

  Next, the wafer 1 is processed by moving the chuck table 4 while irradiating the laser beam 20 from the processing head 18 of the laser processing apparatus 14 to the back surface 1 b side of the wafer 1 and condensing the laser beam 20 inside the wafer 1. To send.

  Then, as shown in FIG. 3A, the modified layer 9 is formed by multiphoton absorption near the condensing point of the laser beam 20 inside the wafer 1. Furthermore, a crack 11 is formed from the formed modified layer 9a to the surface 1a.

  After the modified layer 9 and the crack 11 are formed along the one division line 3, the wafer 1 is indexed and fed, and the modified layer 9 is successively formed along the adjacent division line 3. Cracks 11 are formed. Further, the chuck table 16 is rotated around an axis perpendicular to the holding surface 16a to change the processing feed direction, and the laser beam irradiation is continued in the same manner. When the modified layer 9 and the crack 11 are formed along all the division lines 3, the laser processing step is completed.

  The modified layer 9 is formed, for example, at a depth position of 70 μm to 90 μm from the surface 1a. In the laser processing step, the laser beam may be irradiated a plurality of times while changing the depth position along one division planned line 3. In this case, for example, the modified layer 9 is formed by the first laser beam irradiation, and the second laser beam is applied to the depth position closer to the back surface 1b than the depth position where the first laser beam is irradiated. A crack 11 extending from the modified layer 9 to the surface 1a may be formed by irradiation.

  For example, when the laser processing step is performed without performing the grinding step without depending on the processing method of the wafer, the wafer 1 must be irradiated with a laser beam having a relatively large output in order to form the modified layer 9. I must. As a result, leakage or splash of the laser beam may occur, and the device 5 formed on the wafer 1 may be damaged.

  On the other hand, in the wafer processing method according to the present embodiment, the laser processing step is performed after the grinding step is performed and the wafer 1 is ground and thinned from the back surface 1b side. Therefore, the modified layer 9 is easily formed, and the output of the laser beam can be made relatively small. Therefore, damage to the device 5 due to leakage or splash of the laser beam can be suppressed.

  In the wafer processing method according to the present embodiment, after performing the laser processing step, the groove forming step of removing the modified layer by cutting with a cutting blade is performed. FIG. 3B is a cross-sectional view schematically showing the groove forming step. In the groove forming step, a cutting device 22 shown in FIG. 3B is used. The cutting device 22 includes a chuck table 24 that holds the wafer 1 by suction. The chuck table 24 has the same configuration as the chuck table 4 provided in the above-described grinding apparatus 2.

  The cutting device 22 includes a cutting unit 22 a above the chuck table 24. The cutting unit 22 a includes a spindle 26 that extends parallel to the holding surface 24 a of the chuck table 24, and an annular cutting blade 28 that is attached to one end of the spindle 26. A rotational drive source (not shown) is connected to the other end of the spindle 26, and when the spindle 26 rotates around its extending direction by the rotational drive source, the cutting blade 28 rotates.

  The cutting unit 22a is supported by a notch feed unit (not shown), and the cutting unit 22a can be moved in the vertical direction by the notch feed unit. The chuck table 24 can be moved in a machining feed direction parallel to the holding surface 24a and perpendicular to the extending direction of the spindle 26 by a machining feed unit (not shown). When the chuck table 24 is processed and fed with the cutting blade 28 rotated to cut the cutting blade 28 into the wafer 1, the wafer 1 is cut.

  In the groove forming step, the modified layer 9 is removed by cutting the cutting blade 28 from the back surface 1b of the wafer 1 along the modified layer 9 to a depth not reaching the front surface 1a. At the same time, the grooves 13 are formed along the division lines 3.

  First, similarly to the laser processing step, the wafer 1 is sucked and held on the chuck table 24, and the back surface 1b of the wafer 1 is exposed upward. Next, the relative positions of the cutting edges of the chuck table 24 and the cutting blade 28 are adjusted so that the groove 13 can be formed in the wafer 1 from one end to the other end of the planned dividing line 3 along the planned dividing line 3.

  Then, the rotational drive source is operated to rotate the spindle 26 to rotate the cutting blade 28, and the cutting feed unit is operated to position the cutting blade 28 at a predetermined height position. Here, the predetermined height position refers to the height of the cutting blade 28 when the lower end of the cutting edge of the cutting blade 28 is positioned below the position where the modified layer 9 is formed and does not reach the surface 1a. It is the position.

  Next, the chuck table 24 is moved by the processing feed unit to process and feed the wafer 1. Then, as shown in FIG. 3B, the wafer 1 is cut along the modified layer 9 formed inside the wafer 1 by the cutting blade 28 to remove the modified layer 9, and the groove 13 is formed. Is done.

  After the modified layer 9 is removed and the groove 13 is formed along one division line 3, the wafer 1 is indexed and fed to form the grooves 13 one after another along the adjacent division line 3. Further, the chuck table 24 is rotated around an axis perpendicular to the holding surface 24a to change the processing feed direction, and the cutting of the wafer 1 is continued. Then, when the modified layer 9 is removed along all the planned division lines 3 to form the grooves 13, the groove forming step is completed.

  When the groove forming step is performed, the modified layer 9 is removed from the wafer 1. If the modified layer 9 remains on the wafer 1 or the device chip to be formed, the bending strength is lowered. Therefore, the groove forming step is performed to remove the modified layer 9. When the modified layer 9 is removed by the cutting blade 28, a groove 13 is formed on the back surface 1 b side of the wafer 1, and the back surface 1 b is partitioned by the groove 13.

  In the wafer processing method according to the present embodiment, after the groove forming step, a liquid die-bonding resin is supplied to each region defined by the grooves 13 on the back surface 1b of the wafer 1, and the liquid die-bonding resin is supplied. A resin bonding step for die bonding that solidifies the material is performed.

  The die bonding resin disposing step includes, for example, a coating step of spraying and applying the liquid die bonding resin to the back surface of the wafer in a mist, and solidifying the applied liquid die bonding resin. Forming a thin film layer. In the die bonding resin disposing step, the die bonding resin in which the thin film layers are laminated may be formed by alternately performing the coating step and the solidifying step a plurality of times.

  The resin bonding step for die bonding will be described with reference to FIGS. 4 (A) to 4 (C). FIG. 4A is a cross-sectional view schematically showing the application step, FIG. 4B is a cross-sectional view schematically showing the solidification step, and FIG. 4C is an application performed again. It is sectional drawing which shows a step.

  The resin bonding step for die bonding is performed by a coating apparatus 30 shown in FIGS. 4 (A) to 4 (C). The coating apparatus 30 includes a chuck table 34 for holding the wafer 1. The chuck table 34 is configured in the same manner as the chuck table 4 provided in the grinding apparatus 2 described above.

  The coating device 30 includes a spray unit 32. The spray unit 32 has a spray port (not shown) facing downward, and the spray port is connected to a supply source of a die bond resin (not shown). The spray unit 32 is positioned above the chuck table 34 when the liquid die bond resin is applied, and sprays the liquid die bond resin onto the wafer 1 held on the holding surface 34a of the chuck table 34. Then, a liquid die-bonding resin is applied to the wafer 1.

  In addition, the coating apparatus 30 includes a resin solidifying unit 36 that can be disposed above the chuck table 34. The resin solidifying unit 36 is, for example, an ultraviolet irradiation unit or a heating unit, and is appropriately selected according to the type of the material of the liquid die bonding resin. The resin solidifying unit 36 emits ultraviolet rays, heat, or the like for solidifying the liquid die-bonding resin applied to the wafer 1 sucked and held by the chuck table 34.

  In the resin bonding step for die bonding, first, the wafer 1 having the groove 13 formed on the back surface 1b side is placed on the chuck table 34 of the coating device 30, and the wafer 1 is sucked and held on the chuck table 34. At this time, the front surface 1a side of the wafer 1 is directed toward the holding surface 34a, and the back surface 1b side is exposed upward. And an application | coating step is implemented.

  In the coating step, the spray unit 32 of the coating device 30 is disposed above the chuck table 34 as shown in FIG. Then, the supply source is operated to spray the liquid die bonding resin from the spray port of the spray unit 32 toward the back surface 1 b of the wafer 1. Then, the liquid die-bonding resin is applied to the back surface 1b of the wafer 1 to form a liquid die-bonding resin thin film layer 15a.

  In the application step, the liquid die bonding resin is applied using the grooves 13 formed on the back surface 1b so as to be separated into the respective regions of the back surface 1b defined by the grooves 13. If the amount of the liquid die-bonding resin 15a to be applied is too large, the liquid die-bonding resin is connected between the regions, so that the amount to be applied is adjusted appropriately.

  In the die bonding resin disposing step, after the applying step, a solidifying step of solidifying the liquid die bonding resin thin film layer 15a applied to the back surface 1b of the wafer 1 is performed.

  In the solidification step, as shown in FIG. 4B, the spray unit 32 is moved from above the chuck table 34, and a resin solidification unit 36 is disposed above the chuck table 34 instead. Next, the resin solidifying unit 36 is caused to emit ultraviolet light or heat, for example, and the liquid thin film layer 15a of the die bonding resin formed on the back surface 1b of the wafer 1 is solidified by ultraviolet light or heat.

  By performing the coating step and the solidifying step, the die-bonding resin thin film layer 15 a can be formed on the back surface 1 b of the wafer 1. Here, in the coating step, the supply amount of the liquid die-bonding resin is limited so that the die-bonding resin is not connected between the respective regions of the back surface 1b of the wafer 1, so that the thickness of the thin film layer 15a is insufficient. There is a case.

  In this case, as shown in FIG. 4C, a coating step is further performed to form a thin layer 15b of a liquid die bonding resin on the thin film layer 15a, and a solidification step is performed to form the thin film layer 15b. Solidify. As described above, the coating step and the solidifying step are alternately repeated, and the thin film layer of the die bonding resin is laminated, so that the die bonding resin having a desired thickness is disposed on the back surface 1 b of the wafer 1. Hereinafter, each step will be described by taking as an example a case where a die bonding resin composed of two thin film layers 15a and 15b is disposed on the back surface 1b.

  In the die bonding resin disposing step, the die bonding resins disposed in the respective regions defined by the grooves 13 on the back surface 1 b of the wafer 1 may be slightly connected to each other so as to cross over the grooves 13. In the dividing step described later, when the wafer 1 is divided, the die bonding resin is also divided.

  In the wafer processing method according to the present embodiment, after the die bonding resin placement step, an expanded tape is attached to the back surface 1b of the wafer 1 via the die bonding resin, and the surface 1a of the wafer 1 is further bonded. Then, a replacement step for peeling the protective member 7 is performed. The re-staking step will be described with reference to FIGS. 5 (A) and 5 (B). FIG. 5A is a cross-sectional view schematically showing the re-covering step, and FIG. 5B is a cross-sectional view schematically showing the wafer with the expanded tape attached to the back surface.

  In the replacement step, first, the annular frame 19 is prepared. The annular frame 19 is made of metal, for example. The diameter of the inner peripheral edge of the annular frame 19 is larger than the diameter of the outer peripheral edge of the wafer 1. Then, an annular frame 19 is disposed on the floor surface so as to surround the outer periphery of the wafer 1 placed on a predetermined floor surface with the back surface 1b side exposed upward.

  Next, as shown in FIG. 5A, the expand tape 17 is attached to the annular frame 19 and the wafer 1 from above so as to cover the annular frame 19 and the wafer 1.

  For example, an expanding tape 17 having a width larger than the diameter of the outer periphery of the annular frame 19 is disposed above the annular frame 19 and the wafer 1, and the expanding tape 17 is applied from above by a roller-shaped pressing member 38. Press. Then, after the expand tape 17 is attached to the annular frame 19 and the wafer 1, the expand tape 17 is cut along the outer peripheral edge of the annular frame 19.

  Next, the integrated wafer 1, the annular frame 19, and the expanding tape 17 are turned upside down, and the protective member 7 attached to the surface 1 a side of the wafer 1 is further peeled off. . Then, as shown in FIG. 5B, the protective member 7 is replaced with the expanded tape 17, and the wafer 1 is in a state where the back surface 1 b side is adhered to the expanded tape 17 stretched on the annular frame 19.

  In the wafer processing method according to the present embodiment, after the replacement step, the dividing step of dividing the wafer 1 into individual device chips by expanding the expand tape 17 in the radial direction is performed. The division step will be described with reference to FIGS. 6 (A) and 6 (B). FIG. 6A is a cross-sectional view schematically showing the wafer 1 before the expanding tape 17 is expanded, and FIG. 6B is a cross-sectional view schematically showing the dividing step.

  The expansion tape 17 is divided using a cylindrical expansion drum 40 shown in FIGS. 6A and 6B and a frame holding unit 42 disposed on the outer peripheral side of the expansion drum 40. The frame holding unit 42 includes a plurality of clamps 42 a on the outer periphery of the upper end portion, and the clamps 42 a can sandwich the annular frame 19.

  The expansion drum 40 and the frame holding unit 42 are relatively movable in the vertical direction. When the wafer 1 is placed on the expansion drum 40 via the expand tape 17 stretched on the annular frame 19, the expansion drum 40, the frame holding unit 42, and the like so that the annular frame 19 can be clamped by the clamp 42a. Are adjusted relative to each other.

  As shown in FIG. 6A, in the dividing step, first, the wafer 1 attached to the expanded tape 17 stretched on the annular frame 19 is placed on the expansion drum 40, and the annular frame 19 is clamped by the clamp 42a. To do.

  Next, as shown in FIG. 6B, the expansion drum 40 is moved upward relative to the frame holding unit 42. Then, the expand tape 17 was expanded in the radial direction, the wafer 1 was divided into individual device chips 5a starting from cracks, and a die bonding resin formed by laminating thin film layers 15a and 15b was disposed on the back surface. A device chip 5a is formed.

  When the die bonding resin is slightly connected between the regions defined by the grooves 13 formed on the back surface 1b of the wafer 1, the die bonding resin is also divided when the wafer 1 is divided.

  As described above, according to the wafer processing method according to the present embodiment, the rear surface 1b side of the wafer 1 is ground to thin the wafer 1, and then the modified layer 9 is formed. Therefore, the output of the laser beam irradiated for forming the modified layer 9 can be reduced, and the device can be prevented from being damaged by suppressing the leakage and splash of the laser beam.

  The groove 13 formed on the back surface 1b of the wafer 1 by removing the modified layer 9 formed by the laser beam irradiation with the cutting blade 28 partitions the back surface 1b in units of individual device chips 5a. Since the die bonding resin can be disposed on the back surface 1b so as to be separated by the groove 13, the die bonding resin can be easily disposed so that the process of dividing the die bonding resin is not required.

  In addition, this invention is not limited to description of the said embodiment, A various change can be implemented. For example, in the above embodiment, when the die bonding resin is disposed on the back surface 1b of the wafer 1, a liquid die bonding resin is sprayed and applied to the back surface 1b, and the liquid die bonding resin is solidified. The case where the solidification step is alternately repeated twice has been described. However, one embodiment of the present invention is not limited to this.

That is, for example, the coating step and the solidifying step may be performed once to dispose the die bonding resin, or may be performed alternately three or more times. Further, instead of spraying and applying the liquid die-bonding resin, for example, the die-bonding resin may be applied to the back surface 1b of the wafer 1 by an ink jet method.

  In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention.

DESCRIPTION OF SYMBOLS 1 Wafer 1a Front surface 1b Back surface 3 Scheduled division line 5 Device 7 Protection member 9 Modified layer 11 Crack 13 Groove 15a, 15b Thin film layer 17 Expanding tape 19 Annular frame 2 Grinding device 4, 16, 24, 34 Chuck table 4a, 16a, 24a, 34a Holding surface 6 Grinding unit 8 Spindle 10 Grinding wheel 12 Grinding wheel 14 Laser processing device 18 Processing head 20 Laser beam 22 Cutting device 22a Cutting unit 26 Spindle 28 Cutting blade 30 Coating device 32 Spray unit 36 Resin solidifying unit 38 Press member 40 Expansion drum 42 Frame holding unit 42a Clamp

Claims (2)

A wafer processing method in which division lines are set in a lattice pattern on the surface, and devices are formed in each of a plurality of regions partitioned by the division lines,
A protective member attaching step for attaching a protective member to the surface of the wafer;
A grinding step of thinning the wafer by grinding the back side of the wafer having the protective member adhered to the surface;
By irradiating a laser beam having a wavelength transmissive to the wafer from a thinned back surface side of the wafer along a predetermined division line to a predetermined depth position of the wafer, the modified layer, A laser processing step in which a crack extending from the modified layer toward the surface is formed inside the wafer;
A cutting blade is cut from the back surface of the wafer along the modified layer to a depth that does not reach the surface, thereby removing the modified layer and forming a groove along the division line. A groove forming step,
Supplying a liquid die-bonding resin to each region defined by the groove on the back surface of the wafer, and solidifying the liquid die-bonding resin;
Affixing step of peeling off the protective member from the front surface of the wafer after attaching an expanded tape to the back surface of the wafer via the die bonding resin;
Dividing the wafer into individual device chips starting from the cracks by expanding the expand tape in the radial direction, and forming a device chip having a die bonding resin disposed on the back surface. A wafer processing method characterized by the above. The resin bonding step for die bonding includes:
An application step of spraying and applying the liquid die-bonding resin to the back surface of the wafer in the form of a mist;
Solidifying the applied liquid die bonding resin to form a thin film layer, and
2. The wafer processing method according to claim 1, wherein the die bonding resin in which the thin film layers are laminated is formed by alternately performing the coating step and the solidifying step a plurality of times.