JP2013239664A - Division method of workpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably keep clearances among chips obtained by expansion and division of an expanded sheet that is stuck to a workpiece regardless of a type of the expanded sheet thereby to reduce risk of damages on the chips.SOLUTION: A division method of a workpiece comprises: an expansion step of dividing a wafer (workpiece) 1 from a modified layer 4 by expanding an expanded sheet 11 to form a plurality of chips 3A and form clearances among the chips 3A; a ridge inclination step of inclining a ridge 11b formed by protrusion of an excess that is formed by expansion of the expanded sheet 11 between an outer periphery of the wafer 1 and an inner periphery of an annular frame 10, toward a top face 10b of the annular frame 10; and a press bonding step of press bonding the ridge 11b to the top face 10b of the annular frame 10 thereby to keep clearances among the chips 3A.

Description

  The present invention expands an expanded sheet adhered to an annular frame to divide a plate-like workpiece that is adhered to the expanded sheet and has a divided starting point along the divided starting points, and includes a plurality of chips. The present invention relates to a method of dividing a workpiece to obtain

  In the semiconductor device manufacturing process, a large number of rectangular areas are defined on the surface of a disk-shaped semiconductor wafer by grid-like division lines, electronic circuits such as IC and LSI are formed on the surface of these rectangular areas, and then the back surface After performing necessary processing such as polishing after grinding, the wafer is divided into individual rectangular regions along the planned division lines to obtain a large number of semiconductor chips. The semiconductor chip thus obtained has a film adhesive for die bonding called DAF (Die Attach Film) having a thickness of, for example, about several μm to 100 μm formed of an epoxy resin or the like on the back surface. The DAF is bonded to the die bonding frame that supports the semiconductor chip by heating through the DAF.

  On the other hand, as a method of dividing the plate-like workpiece such as the semiconductor wafer, in addition to cutting with a full cut along the planned division line of the workpiece, division with reduced strength along the planned division line There has also been adopted a method in which an external force is applied to a workpiece after the starting point is formed to cleave the workpiece. Examples of the division starting point include grooves formed by cutting with a cutting blade or irradiating a laser beam. In recent years, a method has been proposed in which a modified layer is formed by irradiating the inside of a workpiece with a transparent laser beam, and the workpiece is divided starting from this modified layer (patent). Reference 1).

  In the dividing method described in Patent Literature 1, an expanded sheet attached to an annular frame can be attached to a workpiece on which a division starting point is formed, and the workpiece can be supported via the annular frame. The expanded sheet is expanded to apply an external force to the workpiece and divide it into a large number of chips. The expanded sheet is expanded by moving the annular frame and the workpiece so as to be relatively spaced apart in a direction perpendicular to the surface of the workpiece, and a space is formed between the divided individual chips. It becomes a state.

  Here, if the expanded sheet in the annular frame remains expanded, the expanded sheet is slack, that is, an excess portion is generated, so that adjacent chips come into contact with each other during handling, and the chip is damaged such as chipped. May occur. Therefore, in the dividing method described in Patent Document 1, the surplus portion of the expanded sheet is substantially reduced by heating and contracting the region between the outer peripheral edge of the workpiece in the expanded sheet and the inner peripheral edge of the annular frame. The distance between the chips is maintained by removing them.

JP 2010-206136 A

  However, depending on the type of the expanded sheet, there is a case where the sheet does not contract sufficiently even when heated and the interval between chips cannot be maintained. If a sufficient space is not formed between the chips, the chips may come into contact with each other and be damaged during handling as described above.

  The present invention has been made in view of the above circumstances, and its main problem is that the chips may be damaged by maintaining the interval between the chips formed by dividing the workpiece regardless of the type of the expanded sheet. An object of the present invention is to provide a method of dividing a workpiece that can reduce the number of workpieces.

  The method for dividing a workpiece according to the present invention includes: a workpiece on which a division starting point is formed; an expanded sheet attached to the workpiece; and an annular frame to which the outer periphery of the expanded sheet is attached. The workpiece side of the workpiece unit is a front surface, the expanded sheet side is a back surface, the workpiece is divided along the division starting point to form a plurality of chips, and between the formed chips A method of dividing a workpiece to maintain a gap, wherein the expanded sheet is expanded, the workpiece is divided from the division starting point to form a plurality of chips, and a gap is formed between the formed chips. An expansion step, and after the expansion step is performed, an excess formed by expanding the expand sheet in the expansion step includes an outer periphery of the workpiece and an inner periphery of the annular frame. A ridge portion tilting step for tilting a bulging portion that is raised between the upper surfaces of the annular frame, and after the ridge portion tilting step is performed, the ridges are crimped to the upper surface of the annular frame to thereby form an interval between the chips. A crimping step for maintaining the pressure.

  According to the present invention, the expanded sheet is expanded in the expansion step to divide the workpiece into chips, and then the protruding portion formed by the expansion of the expanded sheet is tilted to the upper surface of the annular frame to form the annular frame. The excess part of the expanded sheet is substantially removed by pressure-bonding to the upper surface. Since the surplus portion that has become the raised portion is removed by pressure bonding, the surplus portion can be removed even in an expanded sheet that is difficult to shrink by heating, and the spacing between chips can be maintained.

  ADVANTAGE OF THE INVENTION According to this invention, the division | segmentation method of the to-be-processed object which can reduce a possibility that a chip | tip may be damaged by maintaining the space | interval between the chips | tips formed by dividing | segmenting a to-be-processed object irrespective of the kind of expanded sheet is provided The effect that it is done.

It is (a) perspective view, (b) sectional drawing of a wafer unit (workpiece unit) provided with a semiconductor wafer (workpiece) divided by the dividing method concerning one embodiment of the present invention. It is a sectional side view which shows the state which set the wafer unit to the division | segmentation apparatus with which the division | segmentation method of one Embodiment is implemented. It is a sectional side view which shows the expansion step of the division | segmentation method. It is a sectional side view which shows the state which canceled the expansion of the expanded sheet after the expansion step of the division | segmentation method, and formed the excess part of the expanded sheet in the protruding part. It is a sectional side view which shows the protruding part inclination step of the division | segmentation method. It is a sectional side view which shows the crimping | compression-bonding step of the division | segmentation method.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a wafer unit (workpiece unit) 5 according to an embodiment. The wafer unit 5 includes a device wafer (workpiece) 1 to be divided, an expanded sheet 11 adhered to the wafer 1, and an annular frame 10 to which the outer periphery of the expanded sheet 11 is adhered. Is done.

[1] Wafer Unit The wafer 1 is a disk-shaped semiconductor wafer having a thickness of, for example, about several hundred μm. A plurality of rectangular areas 3 are set on the wafer 1 by grid-like division lines 2, and an electronic circuit made of, for example, IC or LSI is formed on the surface 1 a side of the rectangular areas 3.

  A circular expanded sheet 11 attached to the annular frame 10 is attached to the back surface 1b of the wafer 1 so that the front surface 1a side of the wafer 1 is exposed. And the outer periphery of the expand sheet | seat 11 is affixed on the cyclic | annular flame | frame 10, and the wafer unit 5 is comprised. In this wafer unit 5, the wafer 1 side is the front surface 5a, and the expanded sheet 11 side is the back surface 5b. The annular frame 10 is made of a metal plate having rigidity such as stainless steel, and the wafer 1 is handled via the annular frame 10 and the expanded sheet 11.

  The expanded sheet 11 is one in which an adhesive layer is formed on one side of a base material that has elasticity at room temperature and contracts when heated to a predetermined temperature (for example, about 70 ° C.) or higher. . Examples of the substrate include synthetic resin sheets such as polyvinyl chloride, polypropylene, polyethylene, and polyolefin. The wafer 1 and the annular frame 10 are attached to a single-sided adhesive layer. The wafer 1 is disposed concentrically with respect to the circular inner peripheral edge 10 a of the annular frame 10, and the annular region 11 a of the expanded sheet 11 is disposed between the outer peripheral edge 1 c of the wafer 1 and the inner peripheral edge 10 a of the annular frame 10. Is formed.

  As shown in FIG. 1B, a modified layer 4 is formed in advance inside the wafer 1 along the planned division line 2. The modified layer 4 is formed by irradiating the inside of the wafer 1 with a pulse laser beam having a predetermined wavelength having transparency with a converging point aligned. The modified layer 4 has a lower strength than other portions of the wafer 1 and serves as a starting point for division.

  In the present embodiment, the division starting point along the division line 2 of the wafer 1 is the modified layer 4, but the division starting point is not limited to the modified layer 4, and cutting with a cutting blade or irradiation with a laser beam is possible. The groove | channel etc. which were formed in this way may be sufficient.

[2] Dividing Device Next, the wafer 1 is divided along the scheduled dividing line 2 using the modified layer 4 as a dividing starting point to form a plurality of chips and maintain an interval between the formed chips. The dividing method of will be described. In one embodiment, the wafer 1 is divided using the dividing apparatus 20 shown in FIG. First, the configuration of the dividing device 20 will be described.

  The dividing device 20 generates a negative pressure on the table 30 on which the wafer 1 is placed, the annular lifting table 40 on which the annular frame 10 disposed around the table 30 is placed, and the table 30. The suction source 50 is provided.

  The table 30 has a configuration in which a disc-shaped suction portion 33 made of a porous body is fixed to an upper end portion inside the cylindrical frame 31 while being supported on a disc-shaped bottom plate 32. The upper surface of the suction part 33 is a wafer support surface 331, and the wafer support surface 331 is set to have a diameter larger than that of the wafer 1 and smaller than the inner diameter of the annular frame 10. The support surface 331 of the suction part 33 and the upper surface of the cylindrical frame 32 are configured to be flush with each other.

  A suction passage 321 communicating with the suction portion 33 is formed through the center of the bottom plate 32, and a suction source 50 including a vacuum pump for sucking air is connected to the suction passage 321 through a pipe 51. Has been. An opening / closing valve 52 is interposed in the middle of the pipe 51. When the opening / closing valve 52 is opened and the suction source 50 is operated, the inside of the suction unit 33 becomes negative pressure, and the wafer 1 placed on the support surface 331 is sucked and held by the support surface 331.

  The elevating table 40 is disposed around the table 30 so as to be concentric with the table 30 and capable of elevating. The elevating table 40 is moved up and down by expansion and contraction of piston rods 452 of a plurality of cylinders 45 from which piston rods 452 extend upward. To do. As the cylinder 45, a fluid pressure cylinder using air pressure or hydraulic pressure is used. A plurality of movable clamps 41 are attached to the lifting table 40, and the annular frame 10 placed on the lifting table 40 is pressed by these clamps 41 to be in a fixed state.

[3] Division Method Next, a division method according to an embodiment performed using the division apparatus 20 will be described.

(1) Expansion Step As shown in FIG. 2, the height position of the lifting table 40 of the dividing device 20 is the same as that of the table 30, and the wafer unit 5 is placed with the expanded sheet 11 placed on the lower side. While being placed concentrically on the support surface 331 of the table 30, the annular frame 10 is placed on the lifting table 40. In this state, the outer peripheral edge of the cylindrical frame 31 is located in the middle part of the annular region 11 a of the expanded sheet 11. Next, after fixing the annular frame 10 to the lifting table 40 by the clamp 41, the piston rod 452 of each cylinder 45 is contracted and the lifting table 40 is lowered as shown in FIG.

  When the elevating table 40 is lowered, the expand sheet 11 is expanded radially outward. With the expansion of the expand sheet 11, an external force that is pulled outward in the radial direction is applied to the wafer 1, and the wafer 1 is cleaved along the scheduled division line 2 starting from the modified layer 4. That is, the wafer 1 is divided into each rectangular area 3 and divided into a plurality of chips 3A. A space is formed between the chips 3 </ b> A by expanding the expanded sheet 11.

  When the wafer 1 is divided into a plurality of chips 3A, the opening / closing valve 52 is opened and the suction source 50 is operated to suck and hold each chip 3A together with the expand sheet 11 on the support surface 331 of the table 30. As a result, the chip 3A is fixed to the support surface 331 with the distance between the chips 3A being maintained. From this state, as shown in FIG. 4, the piston rod 452 of each cylinder 45 is extended to return the lifting table 40 to the same height as the table 30.

  By this operation, the distance between the outer peripheral edge 1c of the wafer 1 divided into chips 3A and the inner peripheral edge 10a of the annular frame 10 is shortened, so that the expanded state of the annular region 11a of the expanded sheet 11 is released. As a result, as shown in FIG. 4, a surplus portion is generated in the annular region 11 a of the expand sheet 11, and the surplus portion bulges upward and is formed in a raised portion 11 b that overlaps each other.

(2) Raised part tilting step Next, the raised part 11 b formed in the annular region 11 b of the expanded sheet 11 is tilted to the upper surface 10 b of the annular frame 10. In order to tilt the raised portion 11b to the upper surface 10b of the annular frame 10, for example, as shown in FIG. 5, the annular frame on the outer peripheral side from the air ejection nozzle 62 positioned above the raised portion 11b with respect to the raised portion 11b below. Air is ejected obliquely toward the side 10, and the raised portion 11 b is tilted to the upper surface of the annular frame 10 by air pressure.

  The method of the protruding portion tilting step shown in FIG. 5 is an example, and as another method of tilting the protruding portion 11b toward the upper surface 10b of the annular frame 10, the protruding portion 11b is used with an appropriate tool. For example, a method of pushing in the side or sucking using an air suction nozzle positioned above the annular frame 10 may be used.

(3) Crimping step Next, the raised portion 11 b is crimped to the upper surface 10 b of the annular frame 10. In order to crimp the raised portion 11b to the upper surface 10b of the annular frame 10, the above-described raised portion tilting step is continued and the state where the raised portion 11b is inclined to the upper surface 10b of the annular frame 10 is shown in FIG. As shown in the figure, the heater 70 that can be raised and lowered from the upper side is lowered, the heated heater 70 is pressed against the inclined raised portion 11b, and the raised portion 11b is folded onto the upper surface 10b of the annular frame 10 and is crimped. To do. When the raised portion 11b is pressure-bonded, the heater 70 is raised and the processing is completed.

  The heating temperature of the heater 70 is set to about 130 to 140 ° C., for example. In addition, since the surface side of the expanded sheet 11 is an adhesive layer, the pressure-bonding surface on the lower surface of the heater 70 is in contact with the adhesive layer. Therefore, the pressure-bonding surface of the heater 70 is provided with a coating (for example, Tafram coating, “Tafram” is a trademark) so that it can be easily peeled off from the expanded sheet 11 after heat-pressing, or a minute unevenness is formed. Is preferred.

  The crimping step is sequentially performed on a plurality of locations in the annular region 11a of the expanded sheet 11 or simultaneously. Although the number of crimping locations may be two, a plurality of locations equal to the circumference are preferable, for example, 4 to 8 locations are crimped.

  When the crimping step is completed, the suction and holding of the wafer 1 divided into chips 3A on the table 30 is released, and when the annular frame 10 is fixed by the clamp 41, the annular frame 10 is handled and the wafer 1 is carried out. Can do. In the expanded expand sheet 11, the tension on the inner side of the annular frame 10 is maintained by crimping the plurality of raised portions 11b formed in the annular region 11a to the upper surface 10b of the annular frame 10. The distance between the chips 3A is maintained, and the chips 3A do not contact each other.

[4] Effects According to the above embodiment, after the wafer 1 is divided into the plurality of chips 3A, the expanding table 11 is expanded by lowering the elevating table 40 while the wafer 1 is sucked and held on the table 30. The wafer 1 is divided into a plurality of chips 3A. And the excess part is substantially removed by crimping | bonding the several places of the protruding part 11b of the expanded sheet 11 formed by canceling | expanding the expanded sheet | seat 11 to the upper surface 10b of the cyclic | annular frame 10, Thereby, an annular frame The tension of the expanding sheet 11 in 10 is maintained.

  By such a method, even the expanded sheet 11 that is not easily contracted by heating can remove the surplus generated by the expansion, and thus the interval between the chips 3A can be maintained. As a result, the chips 3A do not come into contact with each other during handling, and the risk of damage to the chips 3A is reduced.

  DESCRIPTION OF SYMBOLS 1 ... Wafer (workpiece), 3A ... Chip, 4 ... Modified layer (division start point), 5 ... Wafer unit (workpiece unit), 5a ... Front surface of wafer unit, 5b ... Back surface of wafer unit, 10 ... An annular frame, 10b ... an upper surface of the annular frame, 11 ... an expanded sheet, 11b ... a raised portion.

Claims (1)

The work piece side of the work piece unit comprising a work piece on which a division starting point is formed, an expanded sheet attached to the work piece, and an annular frame to which the outer periphery of the expand sheet is attached. And a side of the expanded sheet as a back side, and dividing the workpiece along the division starting point to form a plurality of chips and maintaining a distance between the formed chips. There,
Expanding the expanded sheet, dividing the workpiece from the division starting point to form a plurality of chips and forming an interval between the formed chips;
After the expansion step is performed, a surplus portion formed by expanding the expand sheet in the expansion step is formed with a raised portion that is raised between the outer periphery of the workpiece and the inner periphery of the annular frame. A ridge tilting step that tilts to the top surface of
After performing the ridge tilting step, a crimping step for maintaining the spacing between the chips by crimping the ridge to the upper surface of the annular frame;
A method for dividing a workpiece, comprising:

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