JP5988599B2 - Workpiece division method - Google Patents

Description

  The present invention relates to a method for dividing a workpiece such as a semiconductor wafer.

  Conventionally, for example, as disclosed in Patent Document 1, after forming a dividing start point such as a modified layer, a laser processing groove, a cutting groove, or the like along a planned dividing line for a workpiece attached to an adhesive tape, In addition, it is divided into individual chips using a dividing device.

  Patent Document 1 discloses a technique for dividing a workpiece by applying an external force to the workpiece by expanding the adhesive tape to which the workpiece is attached. When the adhesive tape stretched by expansion is released from the expanded state, a surplus portion is formed by the stretched portion. Since this surplus portion is in a relaxed state without being applied with tension, there is a concern that adjacent chips after the division may come into contact with each other to cause a defect or breakage.

  In addition, when a DAF (die attach film) consisting of an adhesive layer that acts as an adhesive is mounted on the wafer when the chip is mounted, it is divided with the chip when the adhesive tape is released from the expanded state. There is a concern that the DAFs may come into contact with each other and the DAF may rejoin.

  In this regard, Patent Document 2 discloses a method of maintaining an interval between chips by applying an external stimulus such as heat to an excessive portion of an expanded adhesive tape and contracting the excessive portion. Has been.

JP 2007-189057 A JP 2007-027562 A

  However, even with the technique disclosed in Patent Document 2, there is a concern that shrinkage due to external stimulation is insufficient or does not shrink depending on the material and thickness of the adhesive tape, and further improvement is eagerly desired. Yes.

  The present invention has been made in view of the above problems, and the object of the present invention is to prevent chip chipping / damage and DAF rejoining by preventing contact between the chip and DAF after division. It is another object of the present invention to provide a method of dividing a workpiece that can be prevented.

According to the first aspect of the present invention, before the division start point forming step and the division start point forming step for forming the division start point along the planned division line on the workpiece in which a plurality of the planned division lines intersecting are set. Or, later, an adhesive tape attaching step for attaching a work piece to an adhesive tape having an adhesive layer on the surface and attaching the workpiece to the annular frame via the adhesive tape, a division starting point forming step, and an adhesive tape attaching step are performed. After holding the work piece on the holding table capable of sucking and holding the work piece via the adhesive tape and holding the annular frame with the frame holding means, and after holding the holding step, the holding table And the frame holding means are moved relative to each other in the vertical direction to push up the holding table with respect to the frame holding means and expand the adhesive tape. Dividing the workpiece along the planned division line from the division starting point to form a plurality of chips and forming an interval between adjacent chips, and after carrying out the dividing step, the holding table via the adhesive tape A suction holding step for maintaining the interval between adjacent chips by sucking and holding the workpiece, and after starting the suction holding step, the holding table and the frame holding means are moved relative to each other in the vertical direction to the frame holding means. A raised portion forming step for releasing the push-up of the holding table and forming a raised portion in which the excess portion of the adhesive tape formed by expanding the adhesive tape is raised on the surface of the adhesive tape on the outer peripheral side of the workpiece; after performing part forming step, a raised portion sucked by a suction means an adhesive layer of the adhesive tape from having no back side, the back side of the adhesive tape Adhering a ridge reversing step, after performing the ridges reversing step, and sandwiched between clamping means backside ridge, the inner adhesive layer between the back surface side ridge only to protrude in a rear surface side ridge Thus, there is provided a surplus reduction step of attaching inner parts to each other and reducing surplus parts of the adhesive tape.

  According to invention of Claim 2, after implementing a surplus reduction step, the shrinkage | contraction step which heats the adhesive tape of the outer peripheral side of a to-be-processed object from the surface side of an adhesive tape, and shrinks an adhesive tape is provided. A method of dividing objects is provided.

  According to the present invention, it is possible to prevent a problem that the adhesive tape is bent after the division and the adjacent chips come into contact with each other to be lost or damaged, and a problem that the DAFs on the back surface of the adjacent chips are recombined.

It is a perspective view of the wafer which is a workpiece. It is a perspective view explaining a division starting point formation step. It is a perspective view explaining a tape sticking step. It is a sectional side view explaining a holding step. It is a sectional side view explaining a division | segmentation step. It is a sectional side view explaining a suction holding step. It is a sectional side view explaining a protruding part formation step. (A) is a figure explaining a protruding part. (B) is a figure explaining a protruding part inversion step. (A) is a figure explaining a surplus reduction step. (B) is a figure explaining the state which pinched | interposed the back surface side protruding part between the clamping members. It is a sectional side view explaining the state which removed the wafer and the annular frame. It is a sectional side view explaining a contraction step.

  The present invention is a workpiece dividing method for dividing a workpiece, in which a plurality of intersecting scheduled division lines are set, along the scheduled division line. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Explained.

  FIG. 1 is a diagram showing a semiconductor wafer 11 (hereinafter also simply referred to as “wafer 11”) as an embodiment of a workpiece. The wafer 11 is made of, for example, a silicon wafer having a thickness of 700 μm. A plurality of intersecting division lines (streets) 13 are formed in a lattice shape on the surface 11 a and are partitioned by the plurality of division division lines 13. Devices 15 are respectively formed in the plurality of regions.

  The wafer 11 configured as described above includes a device region 17 where the device 15 is formed, and an outer peripheral surplus region 19 surrounding the device region 17. A notch 12 is formed on the outer periphery of the wafer 11 as a mark indicating the crystal orientation of the silicon wafer. In addition, as a to-be-processed object, the division | segmentation schedule line is not prescribed | regulated, and the thing in which a device is not formed and does not have a pattern is also assumed.

  For the wafer 11 as described above, the method of dividing the workpiece (wafer 11) according to the present invention is performed. First, a division start point forming step for forming a division start point along the planned division line 13 of the wafer 11 is performed.

  As shown in FIG. 2, in this embodiment, the division starting point is formed by forming a modified layer (modified layer) along the division line 13 by the laser processing apparatus. In addition, the formation of the division starting point may be due to the formation of a laser processing groove by a laser processing apparatus or the formation of a cutting groove (half cut) by cutting with a cutting blade.

  FIG. 2 shows a main part of a laser processing apparatus for forming a modified layer along the division line 13 inside the wafer 11. The laser processing apparatus includes a chuck table 10 that holds a wafer 11, a laser beam irradiation unit 2 that irradiates a laser beam onto the wafer 11 held on the chuck table 10, and a CCD that images the wafer 11 held on the chuck table 10. It can comprise and comprise imaging means 4, such as a camera.

  The chuck table 10 is configured to suck and hold the wafer 11, and is moved in a processing feed direction indicated by an arrow X and an index feed direction indicated by an arrow Y in FIG.

  The laser beam irradiation unit 2 has a cylindrical casing 6 arranged substantially horizontally. In the casing 6, pulse laser oscillation means including a pulse laser oscillator such as a YAG laser oscillator or a YVO4 laser oscillator and a repetition frequency setting means is disposed. A condenser 8 for condensing the pulse laser beam oscillated from the pulse laser oscillating means is attached to the tip of the casing 6.

  The imaging unit 4 includes an imaging device (CCD) that captures an image with visible light, and the captured image signal is transmitted to a control unit (not shown).

  Using the laser processing apparatus configured as described above, the chuck table 10 is moved in the direction of the arrow X at a predetermined feed speed while irradiating a pulsed laser beam having transparency to the wafer 11 from the condenser 8. Then, a modified layer (melt rehardened layer) along the division line 13 is formed inside the wafer 11.

The modified layer refers to a region where the density, refractive index, mechanical strength, and other physical characteristics are different from the surroundings. The processing conditions for forming the modified layer are set as follows, for example.
Light source: LD excitation Q switch Nd: YVO 4 pulse laser Wavelength: 1064 nm
Repetition frequency: 100 kHz
Pulse output: 10μJ
Condensing spot diameter: φ1μm
Processing feed rate: 100 mm / sec

  The reformed layer is formed along all the planned dividing lines 13 extending in the first direction (X-axis direction in FIG. 2), and then the chuck table 10 is rotated 90 degrees, and then the first layer is formed. This is carried out along all the planned dividing lines 13 extending in the second direction perpendicular to the direction.

  As described above, the division start point forming step is performed. Next, before or after performing the division starting point forming step, as shown in FIG. 3, the wafer 11 is adhered to an adhesive tape T (tape) having an adhesive layer on the surface and the annular shape is interposed via the adhesive tape T. The adhesive tape attaching step to be attached to the frame F will be described.

  The adhesive tape T is used to apply an external force for separating the wafer 11 to the planned division line when performing a division step described later. The adhesive tape T is provided so as to close the region surrounded by the annular frame F. When the wafer 11 is attached to the adhesive tape T, the wafer 11 is fixed to the annular frame F via the adhesive tape T.

  Next, after performing the split starting point forming step and the adhesive tape attaching step described above, the workpiece is placed on the chuck table 61 (holding table) capable of sucking and holding the wafer 11 via the adhesive tape T. At the same time, a holding step of holding the annular frame F by the frame holding member 66 (frame holding means) is performed.

  In the present embodiment, the holding step is performed by the dividing device 60 shown in FIG. The chuck table 61 of the dividing device 60 is connected to a suction source 67 via a switching valve 69, and a suction holding surface 61 a is formed on the upper surface of the chuck table 61.

  On the side of the chuck table 61, a frame having a placement surface 66a on which the annular frame F is placed and a clamp 68 that holds the annular frame F placed on the placement surface 66a from above. A holding member 66 is disposed. The frame holding member 66 is positioned at a reference position where the mounting surface 66 a is substantially the same height as the suction holding surface 61 a of the chuck table 61.

  In this holding step, the switching valve 69 is turned off, the conduction between the suction source 67 and the suction holding surface 61a is cut off, and suction force (negative pressure) by the suction holding surface 61a does not occur on the back surface of the wafer 11. Yes.

  Next, after carrying out the holding step described above, as shown in FIG. 5, the chuck table 61 and the frame holding member 66 are moved relative to each other in the vertical direction, and the chuck table 61 is pushed up and adhered to the frame holding member 66. By expanding the tape T, the wafer 11 is divided along the planned dividing line from the dividing starting point to form a plurality of chips 15A (devices), and a dividing step is performed in which spaces are formed between adjacent chips 15A. .

  In the present embodiment, the chuck table 61 and the frame holding member 66 are relatively moved in the vertical direction by driving the air cylinder 65 and lowering the frame holding member 66 to the extended position shown in FIG. As a result, the annular frame F held on the mounting surface 66a of the frame holding member 66 is also lowered, so that the adhesive tape T mounted on the annular frame F abuts on the upper edge of the chuck table 61 and mainly has a radius. Expanded in the direction.

  As a result, a tensile force acts radially on the wafer 11 adhered to the adhesive tape T. When a tensile force is applied to the wafer 11 in a radial manner in this way, the strength of the modified layer 20 formed along the planned dividing line 13 (see FIG. 2) is reduced. Thus, the wafer 11 is broken along the modified layer 20 and divided into individual chips 15A.

  Also in this division step, the switching valve 69 is turned off, the conduction between the suction source 67 and the suction holding surface 61a is cut off, and the suction force (negative pressure) by the suction holding surface 61a does not occur on the back surface of the wafer 11. It is said.

  Next, after performing the above dividing step, as shown in FIG. 6, a suction holding step for maintaining the interval between the adjacent chips 15 </ b> A by sucking and holding the wafer 11 via the adhesive tape T by the chuck table 61 is performed. To be implemented.

  That is, in the state where the separation step is completed and the space is formed between the adjacent chips 15A, the switching valve 69 is turned from OFF to ON, and the suction holding surface 61a is communicated with the suction source 67.

  As a result, a negative pressure is generated on the suction holding surface 61a, and each chip 15A is sucked to the suction holding surface 61a via the adhesive tape T, the lateral movement of each chip 15A is restricted, and each chip 15A is regulated. The interval between can be maintained. This suction holding step is continued until at least a surplus reduction step described later is completed.

  Then, after starting this suction holding step, as shown in FIG. 7, the chuck table 61 and the frame holding member 66 are moved relative to each other in the vertical direction to release the pushing up of the chuck table 61 with respect to the frame holding member 66. A protruding portion forming step is performed in which a surplus portion of the adhesive tape T formed by expanding the adhesive tape T forms a raised portion Ta that rises on the surface side of the adhesive tape T on the outer peripheral side of the wafer 11.

  When this bulge forming step is performed, the switching valve 69 is maintained in an ON state, and the suction holding surface 61a and the suction source 67 communicate with each other to maintain the interval between the chips 15A. When the frame holding member 66 is raised to the original position, that is, when the frame holding member 66 is returned to the reference position before the lowering, the position between the suction holding surface 61a and the frame holding member 66 is lowered by the lowering of the frame holding member 66. The portion that has been stretched in is slackened when the tensile force is released, and appears as a surplus portion where no tension is applied.

  Then, as shown in FIG. 8A, the surplus portion bulges to the surface side of the adhesive tape T, that is, the side in the direction in which the frame holding member 66 is returned to the original reference position, and forms a raised portion Ta. It will be. In the raised portion Ta, the adhesive layer Tn of the adhesive tape T appears on the upper side (surface side).

  Next, after performing the above-described raised portion forming step, the raised portion Ta (FIG. 8A) is sucked by the suction mechanism (suction means) 80 from the back side of the adhesive tape T as shown in FIG. 8B. And the protruding part inversion step which makes it protrude in the back surface side of the adhesive tape T and makes it the back surface side protruding part Tb is implemented.

  The suction mechanism 80 includes, for example, a plurality of suction blocks 82 as shown in FIG. 8B in an annular space formed between the periphery of the chuck table 61 and the frame holding member 66 shown in FIG. This can be realized by arranging them in

  In FIG. 8B, the suction block 82 is connected to the suction source 86 via the switching valve 84, and by generating a negative pressure at the suction port 82a formed in the suction block 82, the back side of the adhesive tape T. So that the back side raised portion Tb is formed.

  In the case of the configuration of FIG. 8B, the suction blocks 82 are arranged at a plurality of locations so as to surround the chuck table 61. For example, it is considered that a configuration in which the positions of 90 degrees in the circumferential direction surrounding the chuck table 61 are shifted and arranged at a total of four locations so as to face each other on an extension line of the orthogonal division planned lines 13 (see FIG. 1). It is done.

  Moreover, tension is inherent in the roll winding direction in the roll-shaped adhesive tape. Due to the direction of the tension, wrinkles are likely to occur after expansion in the direction perpendicular to the winding direction of the roll, and the spacing between the chips 15A is difficult to maintain. Therefore, this “interval is maintained perpendicular to the winding direction of the roll. It is conceivable to arrange the suction block 82 at a position where the chuck table 61 is sandwiched between them in the “difficult direction”.

  Further, in addition to the configuration in which the suction blocks 82 are arranged at a plurality of positions as in the present embodiment, a suction mechanism configured by an annular member is configured, and the back surface side bulge is formed around the entire circumference surrounding the chuck table 61. The part Tb may be formed.

  Next, after performing the above-described ridge reversal step, as shown in FIG. 9A, the back side bulge portion Tb is clamped by the clamping mechanism (clamping means) 90 so that the inner portions of the back side bulge portion Tb A surplus reduction step is performed in which the surplus portion of the adhesive tape T is reduced.

  As in the present embodiment, the clamping mechanism 90 can be configured, for example, by disposing clamping members 92 and 92 facing each other with the back-side raised portion Tb interposed therebetween above the suction block 82.

  As shown in FIG. 9 (A), the raised portion reversing step is performed to form the back surface raised portion Tb in the suction block 82, and the holding members 92, 92 are brought closer to each other, so that FIG. As shown in FIG. 2, the back-side raised portion Tb is sandwiched between the sandwiching members 92 and 92.

  In the state of FIG. 9 (A), since the valley-like portion where the adhesive layer Tn is disposed inside is formed in the back side raised portion Tb, the back surface is formed by the sandwiching members 92 and 92 as shown in FIG. 9 (B). When the side bulge portion Tb is sandwiched, the adhesive layers Tn inside the valley-shaped part are adhered to each other.

  And by sticking the inner site | parts of the back surface side protruding part Tb as mentioned above, the part (excess site | part) which was loosened by releasing the tension | tensile_strength among adhesive tape T is eliminated, and it is substantially. The slack of the adhesive tape T is eliminated. And the adhesive tape T can exhibit a tension | tensile_strength by eliminating an excess part.

  As described above, the excess portion (the raised portion Ta and the back-side raised portion Tb) where no tension is applied due to the loosening is eliminated, so that the annular frame F is removed from the frame holding member 66 as shown in FIG. When the adhesive tape T and the chip 15A are removed from the chuck table 61, the adhesive tape T exhibits a tension, and the tension between the chips 15A already formed is maintained by this tension. Can do.

  As described above, it is possible to prevent a problem that the adhesive tape T bends after the division and the adjacent chips 15A and 15A come into contact with each other and are lost or damaged.

  In addition, when a DAF (die attach film) composed of an adhesive layer serving as an adhesive during chip mounting is attached to the back surface of the wafer 11 in advance, the DAF is divided into one piece with the chip 15A. Is done.

  Even when the DAF is attached to the back surface of the chip 15A in this way, the distance between the adjacent chips 15A and 15A is maintained, so that the adhesive tape T bends after the division, and the adjacent chips 15A It is also possible to prevent the problem that the DAFs on the back surface are recombined.

  Furthermore, as a preferred embodiment, as shown in FIG. 11, after performing the surplus reduction step, the shrinking step of shrinking the adhesive tape by heating the adhesive tape T on the outer peripheral side of the wafer 11 from the surface side of the adhesive tape T is performed. I will prepare.

  In the present embodiment, the pressure-sensitive adhesive tape T is contracted by heating the pressure-sensitive adhesive tape T on the outer peripheral side portion of the wafer 11 with a heating unit 96 configured by a lamp (illumination) or a heater. .

  When the adhesive tape T and the chip 15A are removed from the chuck table 61 by shrinking the adhesive tape T on the outer peripheral side of the wafer 11 in this way, the tension is directed outward from the center of the wafer 11. As a result, the interval between the chips 15A and 15A can be maintained more reliably, or the interval can be further increased.

  The form of the heating unit 96 is not particularly limited. For example, the adhesive tape T on the outer peripheral side of the wafer 11 is uniformly heated by causing one heating unit 96 to circulate around the outer periphery of the wafer 11. It is possible to make it.

  Also, as the sheet base material of the adhesive tape T, synthesis of polyvinyl chloride (PVC), polypropylene, polyethylene, polyolefin, etc., which has elasticity at room temperature and contracts by heat at a predetermined temperature (for example, 70 degrees) or more. It is conceivable to use a resin sheet.

11 Wafer 15A Chip 20 Modified layer 60 Dividing device 61 Chuck table 66 Frame holding member 80 Suction mechanism 82 Suction block 86 Suction source 90 Clamping mechanism 92 Clamping member 96 Heating unit F Annular frame T Adhesive tape Ta Raised part Tb Back side raised part Tn adhesive layer

Claims (2)

A division starting point forming step for forming a division starting point along the planned division line on the workpiece in which a plurality of planned division lines intersecting are set,
Before or after carrying out the division starting point forming step, an adhesive tape attaching step for attaching a workpiece to an adhesive tape having an adhesive layer on the surface and attaching the workpiece to the annular frame via the adhesive tape;
After performing the division starting point forming step and the adhesive tape attaching step, the workpiece is placed on the holding table capable of sucking and holding the workpiece via the adhesive tape and the annular frame is held by the frame. Holding step to hold in,
After carrying out the holding step, the holding table and the frame holding means are moved relative to each other in the vertical direction, the holding table is pushed up with respect to the frame holding means, and the adhesive tape is expanded. A dividing step of forming a plurality of chips by dividing along the planned dividing line from the dividing starting point, and forming an interval between the adjacent chips;
After performing the dividing step, a suction holding step for maintaining a distance between the adjacent chips by sucking and holding a workpiece via the adhesive tape on the holding table;
After the suction holding step is started, the adhesive table is formed by extending the holding table and the frame holding means relative to each other in the vertical direction to release the pushing up of the holding table with respect to the frame holding means. A raised portion forming step of forming a raised portion where the surplus portion of the adhesive tape is raised on the outer peripheral side of the workpiece on the surface side of the adhesive tape;
After carrying out the raised portion forming step, the raised portion is sucked from the back side of the adhesive tape that does not have the adhesive layer by suction means, and protrudes only to the back side of the adhesive tape to form a raised side raised portion. Part inversion step,
After performing the ridge reversal step, the back side bulge is sandwiched by clamping means, and the adhesive portions on the inside of the back side bulge are attached to each other so that the inner portions are attached to each other to attach the adhesive tape. A surplus reduction step to reduce surplus parts;
A method of dividing a workpiece comprising: A method of dividing a workpiece according to claim 1,
A method of dividing a workpiece, comprising: a shrinking step of shrinking the pressure-sensitive adhesive tape by heating the pressure-sensitive adhesive tape on the outer peripheral side of the workpiece after the surplus reduction step is performed.

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