JP6298699B2 - Wafer processing method - Google Patents

Description

  The present invention relates to a wafer processing method for manufacturing a semiconductor chip in which a semiconductor wafer is divided and a die bonding adhesive film is attached to the back surface side.

  In the semiconductor device manufacturing process, devices such as ICs and LSIs are formed in a plurality of regions partitioned by dividing lines called streets arranged on the surface of a semiconductor wafer having a substantially disk shape. Then, by cutting the semiconductor wafer along the streets, the semiconductor wafer is divided into regions where devices are formed, and individual semiconductor chips are manufactured. In a semiconductor chip, an adhesive film is attached to the back surface for die bonding in a later process.

  Patent Document 1 discloses a dividing method for dividing such a semiconductor wafer along the street. In Patent Document 1, first, an adhesive film for die bonding is attached to the back surface of each semiconductor chip divided by a prior dicing method or the like, and the individual semiconductor chips are attached to the dicing tape via the adhesive film. To do. Subsequently, the portion of the adhesive film exposed in the gap between each semiconductor chip is irradiated with a laser beam, and then the adhesive film is expanded to break the adhesive film for each semiconductor chip.

  Here, when the semiconductor wafer is divided by the tip dicing method, a division groove is formed on the surface of the semiconductor wafer by so-called half cut, and then a protective tape is attached to the surface of the semiconductor wafer. After the protective tape is attached, the back surface of the semiconductor wafer is ground and thinned to be divided into individual semiconductor chips. After the grinding is completed, an adhesive film for die bonding is attached to the back surface of the semiconductor wafer, and a support tape such as an expanded tape is attached to the adhesive film to support the semiconductor wafer.

JP 2002-118081 A

  After adhering the adhesive film and the support tape, the protective member is peeled off from the semiconductor wafer. However, if the semiconductor wafer is transported after the peeling, the divided semiconductor chip moves and shifts. The cause of this deviation is that the adhesive film shrinks in the tension direction when the adhesive film is attached to the semiconductor wafer. Because the semiconductor chip is misaligned, when irradiating the adhesive film exposed in the gap between the semiconductor chips with a laser beam, the semiconductor chip is accidentally irradiated with the laser beam, or the semiconductor chip is displaced, There is a problem that alignment takes time.

  The present invention has been made in view of these points, and an object of the present invention is to provide a wafer processing method that can suppress an increase in alignment time and prevent erroneous processing of semiconductor chips.

The wafer processing method of the present invention divides a semiconductor wafer in which a plurality of streets are formed in a lattice shape on the surface and devices are formed in a plurality of regions partitioned by the plurality of streets into individual semiconductor chips. A method of processing a wafer in which an adhesive film for die bonding is attached to the back surface of each semiconductor chip, and a split groove forming step of forming a split groove having a predetermined depth along the street from the surface of the semiconductor wafer; After carrying out the protective member attaching process and the protective member attaching process to attach the protective member to the surface of the semiconductor wafer on which the divided grooves are formed, the back surface of the semiconductor wafer is ground and the divided grooves are exposed on the back surface. The divided groove exposing process for separating into individual semiconductor chips and the semiconductor wafer separated into individual semiconductor chips after performing the divided groove exposing process After the adhesive film is mounted on the surface and the adhesive film mounting process in which the back surface of the adhesive film is supported by the support tape and the adhesive film mounting process are performed, the support tape side is placed on the chuck table of the laser processing apparatus, and the support tape And a holding step for sucking and holding the semiconductor wafer on the chuck table via the adhesive film, and a protective member for peeling off the protective member attached to the surface side of the semiconductor wafer held on the chuck table after performing the holding step After performing the peeling step and the protective member peeling step, the adhesive film exposed in the gap between each semiconductor chip is irradiated with a laser beam along the dividing groove from the surface side of the semiconductor wafer held on the chuck table, and bonded. And an adhesive film breaking step of breaking the film along the dividing groove.

  According to this configuration, after the adhesive film side is sucked and held on the chuck table of the laser processing apparatus, the protective member attached to the surface of the semiconductor wafer is peeled off, and the semiconductor is sucked and held on the same chuck table after peeling. Laser processing can be performed while maintaining the distance between the chips. This eliminates the step of transporting the semiconductor wafer in order to irradiate the laser beam after the protective member is peeled off, and in particular eliminates the displacement of the semiconductor chip due to the shrinkage of the adhesive film during the transport. As a result, the alignment of the semiconductor chips can be avoided for a long time, and the adhesive film can be efficiently irradiated with the laser beam from the gap between the semiconductor chips. Further, misalignment of the laser beam to the chip can be prevented by the deviation of the semiconductor chip.

  According to the present invention, it is possible to suppress an increase in alignment time, and to prevent erroneous processing of a semiconductor chip.

It is a perspective view which shows an example of a semiconductor wafer. It is a figure which shows an example of the division | segmentation groove | channel formation process which concerns on embodiment. It is a figure which shows an example of the protection member sticking process which concerns on embodiment. It is a figure which shows an example of the division | segmentation groove | channel exposure process which concerns on embodiment. It is a figure which shows an example of the adhesive film mounting process which concerns on embodiment. It is a figure which shows an example of the holding process which concerns on embodiment. It is a figure which shows an example of the protection member peeling process which concerns on embodiment. It is a figure which shows an example of the laser beam irradiation process in the adhesive film fracture | rupture process which concerns on embodiment. It is a figure which shows an example of the expansion process in the adhesive film fracture | rupture process which concerns on embodiment.

  Hereinafter, a wafer processing method according to the present embodiment will be described with reference to the accompanying drawings. First, a semiconductor wafer will be described with reference to FIG. FIG. 1 is a perspective view showing an example of a semiconductor wafer.

  As shown in FIG. 1, the semiconductor wafer 1 is formed in a substantially disc shape. A surface (upper surface) 1a of the semiconductor wafer 1 is divided into a plurality of regions by streets 2 that are a plurality of intersecting scheduled lines, and a device 3 is formed in each of the divided regions. The semiconductor wafer 1 can be exemplified by a device in which devices such as IC and LSI are formed on a semiconductor substrate such as silicon and gallium arsenide.

  Subsequently, a wafer processing method according to an embodiment of the present invention will be described. The wafer processing method according to the present embodiment is performed in the order of a divided groove forming step, a protective member attaching step, a divided groove exposing step, an adhesive film attaching step, a holding step, a protective member peeling step, and an adhesive film breaking step. The The divided groove forming step, the protective member attaching step, and the divided groove exposing step according to the present embodiment are a processing method called a DBG (Dicing Before Grinding) process, and a semiconductor wafer is divided into individual semiconductor chips for each device. To do. And it is set as the state which the adhesive film adhered to each semiconductor chip by performing an adhesive film mounting process, a holding process, a protection member peeling process, and an adhesive film breaking process.

  The flow of the wafer processing method according to the present embodiment will be described with reference to FIGS. 2 to 9 are explanatory views of each step in the wafer processing method. Note that the steps shown in FIGS. 2 to 9 are merely examples, and the present invention is not limited to this configuration.

  First, the dividing groove forming step shown in FIG. 2 is performed. In this divided groove forming step, the semiconductor wafer 1 is held on the chuck table 11 of a cutting device (not shown) with the surface 1a facing upward. Next, the street 2 is detected by an imaging means (not shown), and the cutting blade 12 is positioned along the detected street 2. Then, the lower end of the cutting blade 12 is positioned so as to reach the middle in the thickness direction of the semiconductor wafer 1. From this state, the cutting blade 12 rotating at high speed and the semiconductor wafer 1 are relatively moved in the extending direction of the street 2. Thereby, in the semiconductor wafer 1, the divided grooves 4 having a predetermined depth are formed along the streets 2 by half-cutting by the cutting blade 12. In addition, the groove depth of the dividing groove 4 is set deeper than the finishing thickness of the semiconductor chip 6 described later.

  After the dividing groove forming step is carried out, as shown in FIG. 3, a protective member attaching step is carried out. In the protective member attaching step, a protective tape 15 (BG (Back Grinding) tape) as a protective member for protecting the semiconductor wafer 1 is attached to the surface 1 a of the semiconductor wafer 1. This sticking can be exemplified by a method of rolling a roller (not shown) or the like on the protective tape 15 and pressing the protective tape 15 against the surface 1 a of the semiconductor wafer 1.

  After the protective member sticking step is performed, as shown in FIG. 4, the dividing groove exposing step is performed. In the divided groove exposing step, the wafer 1 is held on the chuck table 20 of a grinding device (not shown) via the protective tape 15. Further, the grinding means 21 is positioned above the semiconductor wafer 1 held on the chuck table 20. Then, the grinding wheel 22 of the grinding means 21 approaches the rotating chuck table 20 while rotating, and the grinding wheel 22 and the back surface 1b of the semiconductor wafer 1 are in rotational contact with each other in a parallel state so that the semiconductor wafer 1 is in a predetermined state. Grind to the final thickness. By this grinding, the dividing grooves 4 are exposed on the back surface 1 b of the semiconductor wafer 1, and the semiconductor wafer 1 is divided into individual semiconductor chips 6 according to the devices 3.

  After the protective member attaching step is carried out, an adhesive film attaching step is carried out as shown in FIG. In the adhesive film mounting process, first, an adhesive film 25 made of a die bonding film (DAF: Die Attach Film) is attached to the surface of the support tape 26, and the outer peripheral side of the support tape 26 is attached to the annular frame 27. Worn. By this sticking, the adhesive film 25 is disposed inside the frame 27, and the adhesive film 25 is integrated with the frame 27 via the support tape 26. Thereafter, the adhesive film 25 integrated with the frame 27 is pressed against the back surface 1b of the semiconductor wafer 1 via a roller or the like. Thus, the front surface (lower surface in the figure) of the adhesive film 25 is mounted on the back surface 1b of the semiconductor wafer 1 divided into individual semiconductor chips 6, and the back surface (upper surface in the figure) of the adhesive film 25 is supported by the support tape 26. It becomes a state. In this state, the semiconductor wafer 1 is mounted on the frame 27 via the adhesive film 25 and the support tape 26 and these are integrated, so that the semiconductor wafer 1 can be transported while holding the frame 27. Moreover, since the protective tape 15 is stuck on the surface 1a, the semiconductor wafer 1 is in a state of being sandwiched and fixed between the adhesive film 25, the support tape 26, and the protective tape 15 (see FIG. 6). ).

  In FIG. 5, the illustration of the table on which the semiconductor wafer 1 is placed is omitted. However, when the adhesive film 25 is stuck as described above, the semiconductor wafer 1 is placed on the chuck table 20 in FIG. Alternatively, it may be placed on a table of a sticking device (not shown). In addition, the adhesive film 25 and the support tape 26 may be integrally laminated in advance.

  After the adhesive film mounting step is performed, a holding step is performed as shown in FIG. In the holding step, the protective member peeling step and the adhesive film breaking step, which will be described later, a chuck table 30 constituting a laser processing apparatus (not shown) is used. The chuck table 30 has a holding surface 32 formed of a porous ceramic material 31, and the holding surface 32 is formed in a planar shape slightly smaller than the semiconductor wafer 1. The holding surface 32 is connected to a suction source (not shown) through a flow path 33 in the chuck table 30. Clamp portions (not shown) are provided at a plurality of locations around the chuck table 30, and the frame 27 around the semiconductor wafer 1 is sandwiched and fixed via the clamp portions.

  In the holding step, the semiconductor wafer 1 integrated with the frame 27 is transferred to the chuck table 30 and the support tape 26 side is placed on the holding surface 32. The holding surface 32 is communicated with a suction source, and the semiconductor wafer 1 is sucked and held on the chuck table 30 via the support tape 26 and the adhesive film 25.

  After the holding step is performed, a protective member peeling step is performed as shown in FIG. In the protective member peeling step, the protective tape 15 attached to the surface 1a side of the semiconductor wafer 1 is peeled in a state where the suction holding by the holding step is maintained. This peeling may be performed manually by an operator, or an operation of grasping one end of the protective tape 15 by a peeling device (not shown) and gradually expanding the peeling area while folding back toward the other end of the protective tape 15. You may go.

  After the protective member peeling step is performed, the adhesive film breaking step is performed. In the adhesive film breaking step, first, a laser beam irradiation process is performed as shown in FIG. In the laser beam irradiation process, first, the street 2 or the divided groove 4 is detected by an imaging unit (not shown). Thereafter, based on the detection result of the imaging means, alignment is performed so that the exit of the processing head 35 constituting the laser processing apparatus (not shown) is positioned in the dividing groove 4. After alignment, the processing head 35 irradiates a laser beam from the surface 1a side of the semiconductor wafer 1 to the adhesive film 25 exposed in the gaps in the dividing grooves 4 between the semiconductor chips 6. The laser beam has a wavelength having an absorptivity with respect to the adhesive film 25, and is adjusted so that the condensing point is positioned on the surface (upper surface in the drawing) of the adhesive film 25.

  Then, by moving the semiconductor wafer 1 and the processing head 35 relative to each other, a laser beam is irradiated along all the divided grooves 4, and a modified region is formed on the surface of the adhesive film 25 inside each divided groove 4. . This modified region refers to a region where the density, refractive index, mechanical strength and other physical characteristics of the surface of the adhesive film 25 differ from the surroundings due to the irradiation of the laser beam, and the strength is lower than the surroundings. The modified region is, for example, a melt treatment region, a crack region, a dielectric breakdown region, or a refractive index change region, and may be a region where these are mixed.

  In the adhesive film breaking step, after the laser beam irradiation process is performed, an expanding process is performed as shown in FIG. In the expanding process, the frame 27 is placed on the annular table 41 of the tape expansion device (not shown), and the frame 27 is held on the annular table 41 by the clamp portion 42. Further, the outer diameter of the expansion drum 43 is smaller than the inner diameter of the frame 27, and the inner diameter of the expansion drum 43 is larger than the outer diameter of the semiconductor wafer 1. For this reason, the upper end portion of the expansion drum 43 is brought into contact with the support tape 26 between the semiconductor wafer 1 and the frame 27.

  From this state, when the frame 27 is lowered together with the annular table 41, the expansion drum 43 is raised relative to the annular table 41, and the support tape 26 is expanded in the radial direction. By extending the support tape 26, tension is applied to the adhesive film 25, and the adhesive film 25 is broken and divided along the dividing groove 4 starting from the modified region. Thereby, the space | interval of each semiconductor chip 6 is expanded, and will be in the state which the small piece-like adhesive film 25 fractured | ruptured in the position of the division | segmentation groove | channel 4 in each of several semiconductor chips 6 in this state.

  As described above, the semiconductor chips 6 arranged at intervals on the support tape 26 are adsorbed by a pickup collet (not shown) and peeled off from the support tape 26. At this time, even if the suction source 47 is connected to the holding table 45 formed inside the upper part of the expansion drum 43 by switching the opening / closing valve 46, the position of the semiconductor chip 6 is regulated by sucking and holding the support tape 26. Good. The semiconductor chip 6 to which the adhesive film 25 is adhered is bonded by pressure bonding the adhesive film 25 side to a die bonding frame (not shown).

  As described above, according to the processing method according to the present embodiment, both the peeling of the protective tape 15 and the processing by the laser beam irradiation from the processing head 35 can be performed while performing suction holding on the chuck table 30. it can. Thereby, after peeling off the protective tape 15, it is not necessary to transport the semiconductor wafer 1 in order to irradiate the inside of the dividing groove 4 with a laser beam, and the semiconductor chip 6 is not displaced due to the shrinkage of the adhesive film 25 during the transportation. Can be prevented. Through preventing the semiconductor chip 6 from shifting, the time required for alignment before laser beam irradiation can be shortened, and erroneous processing of irradiating the semiconductor chip 6 with the laser beam can be avoided.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the laser beam irradiation treatment described above, the modified region may be formed continuously along the dividing groove 4 on the adhesive film 25 or may be formed intermittently.

  Moreover, in said embodiment, said each process may be implemented with a separate apparatus, and may be implemented with the same apparatus.

  As described above, the present invention has an effect of preventing erroneous processing of a semiconductor chip while suppressing an increase in alignment time, and in particular, a wafer processing method in which an adhesive film is attached to each semiconductor chip. Useful for.

DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 1a Front surface 1b Back surface 2 Street 3 Device 4 Dividing groove 6 Semiconductor chip 15 Protective tape (protective member)
25 Adhesive film 26 Support tape 30 Chuck table

Claims (1)

A semiconductor wafer in which a plurality of streets are formed in a lattice pattern on the front surface and devices are formed in a plurality of regions partitioned by the plurality of streets is divided into individual semiconductor chips, and the back surface of each individual semiconductor chip A wafer processing method for mounting an adhesive film for die bonding on
A split groove forming step of forming a split groove of a predetermined depth along the street from the surface of the semiconductor wafer;
A protective member adhering step for adhering a protective member to the surface of the semiconductor wafer on which the divided grooves are formed;
After carrying out the protective member attaching step, the rear surface of the semiconductor wafer is ground to expose the divided grooves on the rear surface, and divided groove exposing step for separating into individual semiconductor chips;
After performing the dividing groove exposing step, the adhesive film is attached to the back surface of the semiconductor wafer separated into individual semiconductor chips, and the adhesive film attaching step of supporting the back surface of the adhesive film with a support tape;
A holding step of placing the support tape side on a chuck table of a laser processing apparatus after performing the adhesive film mounting step, and sucking and holding the semiconductor wafer to the chuck table via the support tape and the adhesive film; ,
After carrying out the holding step, a protective member peeling step for peeling off the protective member attached to the surface side of the semiconductor wafer held on the chuck table ;
After carrying out the protective member peeling step, the adhesive film exposed to the gap between the semiconductor chips from the surface side of the semiconductor wafer held on the chuck table is irradiated with a laser beam along the dividing groove, An adhesive film breaking step for breaking the adhesive film along the divided grooves;
A method for processing a wafer, comprising:

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