JP6741529B2 - Tip spacing maintenance method - Google Patents

Description

The present invention relates to a chip interval maintaining method for maintaining a state in which intervals between a plurality of chips constituting a workpiece are expanded on an expand sheet.

A plate-shaped work piece such as a semiconductor wafer is divided into a plurality of regions by dividing lines whose surface is arranged in a grid pattern, and various devices are arranged in each of the grid-shaped regions. Each is formed. Then, the workpiece is ground and thinned to a predetermined thickness, and then divided along a dividing line into individual device chips or the like, which are used in various electronic devices and the like.

As a method of dividing the work piece, for example, first, a laser beam is focused inside the work piece to form a modified layer as a division starting point, and an external force is applied to a division line whose strength is reduced by the modified layer. There is a method of dividing the work piece into chips by adding. As a means for applying an external force, there is adopted a means in which the expandable sheet attached to the back surface of the workpiece is expanded by an expanding device to simultaneously expand the workpiece (see, for example, Patent Document 1). That is, while attaching the expandable sheet to the work piece, by attaching the outer peripheral portion of the expandable sheet to the annular frame so as to close the opening of the annular frame, the work piece is attached to the annular frame through the expandable sheet. Put in a supported state. Next, the work piece supported via the annular frame is placed on the expansion drum of the expanding device, and the expanding sheet is expanded in the surface direction, so that an external force is applied to the planned dividing line whose strength is reduced by the modified layer. In addition, the work piece can be divided into chips.

JP, 2010-147317, A

After expanding the expandable sheet and dividing the workpiece appropriately into chips, and providing a predetermined gap between the chips, the divided workpieces are separated from the expandable sheet while the expandable sheet is still attached. It is transported to the pickup process for picking up. In the pickup step, for example, a chip is pushed up from below by a needle and the chip lifted from the expand sheet is picked up by a vacuum chuck. When the expanded sheet is expanded and the tension is released, the region between the inner peripheral edge of the annular frame and the outer peripheral edge of the workpiece is stretched and becomes slackened, so that the expanded frame is conveyed during the pickup process. When the workpiece is handled through, the chips may come into contact with each other due to the slack of the expand sheet, and the chips may be damaged.

Therefore, as described in Patent Document 1, after the work piece is divided into chips, only the slack region between the inner peripheral edge of the annular frame and the outer peripheral edge of the work piece is heated in the expanded sheet. Then, there is a method of shrinking the chips and preventing the chips from coming into contact with each other without shrinking the part to which the chips are attached.

However, when the expand sheet to which the work piece is attached is of a type that does not shrink or does not easily shrink by heating, it is possible to accurately shrink even if the slack area of the expand sheet is heated. As a result, when the workpiece is handled through the annular frame, the chips may come into contact with each other and the chips may be damaged.

Therefore, even when the expanded sheet that does not shrink or does not easily shrink by heating is attached to the workpiece, while maintaining the state in which the interval between the chips is expanded, the chips due to the slack of the expand sheet There is a problem of preventing contact and damage.

The present invention for solving the above-mentioned problems is maintained in a state in which an interval between a plurality of chips constituting a workpiece supported by an annular frame through the expand sheet in the state of being attached to the expand sheet is expanded. A method for maintaining the tip spacing , wherein the expand sheet is fixed on the holding surface of the annular table, and the expand sheet is not suction-held by the suction surface of the suction-holding table arranged on the inner peripheral side of the annular table. In a state of being supported, the holding surface and the suction surface are relatively moved in the vertical direction to expand the expand sheet to form a space between the chips, and a chip space forming step. After the operation, the region of the expand sheet corresponding to the chips is suction-held by the suction surface of the suction-holding table and the space between the chips is maintained, and the inner peripheral edge of the annular frame and the outer peripheral edge of the workpiece are held. An expanded sheet shrinking step of shrinking the expanded sheet stretched on the outer peripheral side of the workpiece by heating the expanded sheet between and, at least before carrying out the expanded sheet shrinking step, an annular shape The method further comprises a heat shrink tape attaching step of attaching a plurality of rectangular heat shrink tapes to the expand sheet between the inner peripheral edge of the frame and the outer peripheral edge of the workpiece, and in the expand sheet shrink step, the heat shrink tape attaching step A method of maintaining a chip interval, in which an expanded sheet between a peripheral edge and an outer peripheral edge of a workpiece is heated together with the heat-shrinkable tape to shrink the expanded sheet in a region to which the heat-shrinkable tape is attached.

The chip interval maintaining method according to the present invention, while fixing the expand sheet on the holding surface of the annular table, in a state where the expand sheet is not sucked and held by the suction surface of the suction holding table disposed on the inner peripheral side of the annular table. Supporting, the holding surface and the suction surface are relatively moved in the up-and-down direction to expand the expand sheet to form a gap between the chips to form a gap between the chips, and after performing the tip gap forming step, While the area corresponding to the chips is suction-held by the suction surface of the suction-holding table and the spacing between the chips is securely maintained, the expand sheet between the inner peripheral edge of the annular frame and the outer peripheral edge of the workpiece is heated. An expanding sheet contracting step of contracting the expanded sheet stretched on the outer peripheral side of the workpiece, and at least before performing the expanding sheet contracting step, the inner peripheral edge of the annular frame and the outer peripheral edge of the workpiece. A heat-shrink tape attaching step of attaching a plurality of rectangular heat-shrink tapes to the expand sheet between the expand sheet and the expand sheet between the inner peripheral edge of the annular frame and the outer peripheral edge of the workpiece in the expand sheet shrink step. By heating the heat shrinkable tape together with the heat shrinkable tape, the heat shrinkable tape is shrunk by heating to shrink the expanded sheet in the region where the heat shrinkable tape is attached, so that it is possible to shrink even the expanded sheet that does not shrink by heating. In addition, the distance between the chips can be surely maintained in the expanded state. Therefore, it is possible to prevent the chips from being damaged due to the chips coming into contact with each other due to the slack of the expand sheet.

It is a perspective view which shows an example of a to-be-processed object and a protective tape. It is sectional drawing which shows the state which has formed the modified layer inside the to-be-processed object with a laser processing apparatus. FIG. 3 is a perspective view showing a state in which the back surface of the work piece is ground by a grinding device to be thinned to a predetermined thickness, and the work piece is divided into chips by a grinding pressure. FIG. 4 is a perspective view showing a state in which the work piece is attached to the expand sheet, supported by the annular frame, and the protective tape is peeled off from the work piece. It is a top view showing an example of the state where a plurality of heat-shrink tapes were stuck on the expand sheet between the inner peripheral edge of the annular frame and the outer peripheral edge of the workpiece. FIG. 7 is a cross-sectional view showing a state in which the divided work piece attached to the expand sheet and supported by the annular frame is set in the chip interval expanding device. It is sectional drawing which shows the state which has formed the predetermined space|interval between each chip by expanding the expand sheet|seat by the chip space expansion device. By a cross-sectional view showing a state of shrinking the expand sheet in the region where the heat shrink tape is attached by heating the expand sheet between the inner peripheral edge of the annular frame and the outer peripheral edge of the workpiece together with the heat shrink tape. is there.

The workpiece W shown in FIG. 1 is, for example, a semiconductor wafer having a circular outer shape, and on the front surface Wa of the workpiece W, a large number of devices D are arranged in a grid-like region divided by the planned dividing line S. Are formed. When the workpiece W is divided into each chip including the device D along the planned dividing line S, for example, the modified layer serving as the division starting point is formed inside the workpiece W by the laser processing apparatus 1 shown in FIG. Is formed. Therefore, the protective tape T1 shown in FIG. 1 is in a state of being attached to the front surface Wa.

The protective tape T1 is, for example, a disk-shaped film having an outer diameter similar to the outer diameter of the workpiece W, and has an adhesive surface T1a having an adhesive force. For example, the adhesive surface T1a is made of UV-curing glue made of an acrylic base resin or the like, which is hardened by being irradiated with ultraviolet rays and its adhesive strength is reduced. By sticking the sticking surface T1a of the protective tape T1 to the front surface Wa of the workpiece W, the front surface Wa of the workpiece W is protected by the protective tape T1.

The laser processing apparatus 1 includes, for example, at least a chuck table 10 that sucks and holds the workpiece W, and a laser light irradiation unit 11 that irradiates the workpiece W held by the chuck table 10 with laser light. ing. The chuck table 10 has, for example, a circular outer shape, and holds the workpiece W by suction on the holding surface 10a made of a porous member or the like. The chuck table 10 is rotatable about an axis in the vertical direction, and is reciprocally movable in the X-axis direction by the processing feeding means 12.

The laser light irradiation means 11 includes, for example, a laser light oscillator (not shown) capable of oscillating a laser light having a predetermined wavelength that is transparent to the workpiece W, and collects the laser light oscillated from the laser light oscillator. By entering the light into the condenser lens 112 inside the optical device 111, the laser light can be condensed inside the workpiece W. For example, when the workpiece W is a silicon wafer and it is desired to form a favorable modified layer inside the workpiece W by the laser light irradiation means 11, laser light having a wavelength in the infrared region is emitted from the laser light oscillator. Oscillate.

In the vicinity of the laser light irradiation means 11, an alignment means 14 for detecting the planned dividing line S of the workpiece W is arranged. The alignment unit 14 includes an infrared irradiation unit (not shown) that emits infrared rays, and an infrared camera 140 that includes an optical system that captures the infrared rays and an image sensor (infrared CCD) that outputs an electric signal corresponding to the infrared rays. Based on the image acquired by the infrared camera 140, the planned dividing line S of the front surface Wa of the workpiece W can be detected by image processing such as pattern matching. The laser beam irradiation means 11 is configured integrally with the alignment means 14, and both move in the Y-axis direction and the Z-axis direction in conjunction with each other.

Hereinafter, a case will be described in which the laser processing apparatus 1 is used to form a modified layer serving as a division start point on the workpiece W along the planned division line S. First, alignment is performed so that the holding surface 10a of the chuck table 10 of the laser processing apparatus 1 shown in FIG. 2 and the front surface Wa side of the workpiece W protected by the protective tape T1 face each other, and the workpiece W is processed. Is placed on the chuck table 10 with the back surface Wb side facing upward. Then, a suction source (not shown) connected to the chuck table 10 is activated to hold the workpiece W on the chuck table 10 by suction.

Next, the processing feed means 12 sends the workpiece W held on the chuck table 10 in the −X direction (forward direction), and the alignment means 14 detects the planned dividing line S. Here, the front surface Wa of the workpiece W on which the planned dividing line S shown in FIG. 1 is formed is located on the lower side and does not directly face the alignment means 14, but the workpiece W by the infrared camera 140 is used. The planned dividing line S can be imaged by being transmitted from the back surface Wb side. The alignment unit 14 performs image processing such as pattern matching on the image of the planned division line S captured by the infrared camera 140, and the position of the planned division line S is detected.

As the planned dividing line S is detected, the laser beam irradiation means 11 is driven in the Y-axis direction, and the planned dividing line S for irradiating the laser beam and the condenser 111 are aligned in the Y-axis direction. It This alignment is performed, for example, so that the center line of the planned dividing line S is located immediately below the condenser lens 112 provided in the condenser 111.

Then, the condenser 111 positions the focal point of the laser light having a predetermined wavelength at a predetermined height inside the workpiece W corresponding to the planned dividing line S. Then, while irradiating the laser light oscillated from the laser light oscillator and condensed by the condenser lens 112 along the planned dividing line S, the workpiece W is processed and fed in the −X direction at a predetermined machining feed speed, As shown in FIG. 2, the modified layer M is formed inside the workpiece W. The formation position of the modified layer M is, for example, a position between the back surface Wb and the front surface Wa of the workpiece W and the position above the finished thickness of the device chip by the finished thickness.

For example, when the workpiece W advances in the −X direction to a predetermined position in the X-axis direction where the irradiation of the laser light on one planned dividing line S is completed, the irradiation of the laser light is stopped and the − The machining feed in the X direction (forward direction) is once stopped, the laser light irradiation means 11 is moved in the +Y direction, and the laser light irradiation means 11 is positioned next to the planned dividing line S irradiated with the laser light and the laser light is still irradiated. Positioning of the non-planned dividing line S and the condenser 111 in the Y-axis direction is performed. Next, the processing feed means 11 processes and feeds the workpiece W in the +X direction (return direction), and the planned dividing line S is irradiated with the laser light similarly to the irradiation of the laser light in the outward direction. By sequentially irradiating the same laser light, the laser light is radiated from the back surface Wb side of the workpiece W along all the planned dividing lines S extending in the X-axis direction, and a division starting point is formed inside the workpiece W. The modified layer M is formed. Further, when the chuck table 10 is rotated by 90 degrees and the same laser light irradiation is performed, the modified layer M is formed along all the planned dividing lines S in the vertical and horizontal directions.

The workpiece W on which the modified layer M is formed is, for example, the back surface Wb of the workpiece W is ground by the grinding device 2 shown in FIG. The cracks are extended to the surface Wa side with the division starting point as the division starting point, so that each device chip is divided.

The grinding device 2 includes, for example, at least a holding table 20 that sucks and holds the workpiece W, and a grinding unit 21 that grinds the workpiece W held by the holding table 20. The holding table 20 has, for example, a circular outer shape, and holds the workpiece W by suction on the holding surface 20a formed of a porous member or the like. The holding table 20 is rotatable about an axis in the vertical direction, and is reciprocally movable in the Y-axis direction by the Y-axis feed means 23.

The grinding means 21 can be moved up and down by a grinding feed means 22 that feeds the grinding means 21 in the Z-axis direction away from or closer to the holding table 20. The grinding feed means 22 is, for example, a ball screw mechanism operated by a motor or the like. The grinding means 21 includes a rotary shaft 210 whose axial direction is a vertical direction (Z-axis direction), a motor 212 for rotationally driving the rotary shaft 210, an annular mount 213 connected to the lower end of the rotary shaft 210, and a mount. And a grinding wheel 214 detachably connected to the lower surface of 213.

The grinding wheel 214 includes a wheel base 214a and a plurality of substantially rectangular parallelepiped grinding wheels 214b that are annularly arranged on the bottom surface of the wheel base 214a. The grinding wheel 214b is formed by fixing diamond abrasive grains or the like by, for example, resin bond or metal bond. The shape of the grinding wheel 214b may be integrally formed in a ring shape.

For example, inside the rotary shaft 210, a flow path (not shown) that communicates with the grinding water supply source and serves as a passage for the grinding water is formed so as to penetrate in the axial direction (Z-axis direction) of the rotary shaft 210. The path passes through the mount 213 and is opened at the bottom surface of the wheel base 214a so that the grinding water can be ejected toward the grinding wheel 214b.

Hereinafter, a case where the grinding device 2 grinds and divides the workpiece W will be described. First, the workpiece W is placed on the holding surface 20a with the back surface Wb side facing upward so that the center of the holding table 20 and the center of the workpiece W substantially match. Then, the suction force generated by a suction source (not shown) is transmitted to the holding surface 20a, so that the holding table 20 sucks and holds the workpiece W.

Then, the holding table 20 holding the workpiece W moves in the +Y direction to the bottom of the grinding means 21, and the grinding wheel 214 provided in the grinding means 21 and the workpiece W are aligned. For the alignment, for example, as shown in FIG. 3, the center of rotation of the grinding wheel 214 is deviated in the +Y direction by a predetermined distance from the center of rotation of the holding table 20, and the rotation path of the grinding wheel 214b rotates the holding table 20. It goes through the center.

After the grinding wheel 214 provided in the grinding means 21 is aligned with the workpiece W, the grinding wheel 214 is rotated as the rotary shaft 210 is rotationally driven in the counterclockwise direction when viewed from the +Z direction side. Rotate. Further, the grinding means 21 is fed in the -Z direction by the grinding feed means 22, and the grinding wheel 214b of the rotating grinding wheel 214 contacts the back surface Wb of the workpiece W to perform the grinding process. During the grinding, as the holding table 20 rotates, the workpiece W held on the holding surface 20a also rotates, so that the grinding wheel 214b grinds the entire back surface Wb of the workpiece W. .. Further, during the grinding process, the grinding water is supplied to the contact portion between the grinding wheel 214b and the workpiece W through the flow path in the rotary shaft 210, and the grinding wheel 214b and the back surface Wb of the workpiece W are supplied. Cool and wash the contact area of.

When the grinding is continued and the work W is thinned to the final thickness, the cracks extend toward the surface Wa of the work W by the grinding pressure acting along the modified layer M, and the work W As shown in FIG. 3, W is divided into rectangular device chips C.

As shown in FIG. 4, the workpiece W divided into the chips C is affixed to the expand sheet T2, and the state supported by the annular frame F via the expand sheet T2 is maintained and the workpiece W is interposed therebetween. The handling is enabled and the protective tape T1 is peeled off.

The expanded sheet T2 is, for example, a disk-shaped sheet having an outer diameter larger than the outer diameter of the workpiece W, and has, for example, a heat shrinkability that is small, and a PET that is appropriately stretchable with respect to a mechanical external force. It is equipped with a base material layer composed of a (polyethylene terephthalate) resin stretched film or a PEN (polyethylene naphthalate) resin film. The adhesive surface T2a formed by stacking is provided. The material, thickness, and the like of the base material layer of the expanded sheet T2 can be appropriately changed depending on the type of the workpiece W, the thickness of the workpiece W, and the like.

In FIG. 4, the back surface Fb of the annular frame F having a circular opening is attached to the outer peripheral portion of the adhesive surface T2a of the expanded sheet T2 facing upward. Further, the workpiece W is positioned above the adhesive surface T2a of the expanded sheet T2 exposed in the opening of the annular frame F with the back surface Wb side facing downward. At this time, the center of the workpiece W is aligned so as to substantially coincide with the center of the opening of the annular frame F. Then, the back surface Wb of the workpiece W is pressed against the adhesive surface T2a of the expand sheet T2, and the expand sheet T2 is attached to the back surface Wb of the workpiece. In this way, the workpiece W is brought into a state of being supported by the annular frame F via the expanded sheet T2, and the protective tape T1 is peeled off from the front surface Wa of the workpiece W.

Next, the expand sheet T2 is expanded so that a predetermined interval is formed between the chips C supported by the annular frame F via the expand sheet T2. This is because the workpiece W divided into the chips C and supported by the annular frame F through the expanded sheet T2 has the shape of the workpiece W as a whole and there is no space between the chips C. This is to prevent the adjacent chips C from rubbing against each other during conveyance of the workpiece W or when picking up the chips C from the expanded sheet T2 and chipping of chips to deteriorate the quality of the chips C. ..

However, since the region T2c between the inner peripheral edge Fe of the annular frame F of the expanded expanded sheet T2 and the outer peripheral edge Wd of the workpiece W extends and becomes loose, the workpiece processed through the annular frame F is processed. At the time of handling the object W, it is necessary to prevent the chips C from coming into contact with each other and damaging the chips C due to the slack of the expand sheet T2. Therefore, the chip interval maintaining method according to the present invention will be carried out below.

(1) Heat Shrink Tape Adhesion Step For example, in the present embodiment, a plurality of heat shrink tapes T3 are provided in a region T2c between the inner peripheral edge Fe of the annular frame F of the expanded sheet T2 and the outer peripheral edge Wd of the workpiece W. First, the step of attaching the heat-shrinkable tape for attaching the. The heat-shrinkable tape T3 is made of, for example, a resin (for example, polypropylene or polyvinyl chloride) having at least a heat shrinkage greater than that of the expanded sheet T2 and an appropriate stretchability against a mechanical external force, and its outer shape is rectangular. It is formed in a shape. The heat-shrinkable tape T3 has an adhesive surface made of a glue layer in the present embodiment, but may have no adhesive surface. The rectangular heat-shrink tape T3 can reduce the cost and can be attached more easily than, for example, the heat-shrink tape whose outer shape is formed in a ring shape. That is, for example, the rectangular heat-shrinkable tape T3 can be cut out only by cutting the long heat-shrinkable tape into a straight line, but the ring-shaped heat-shrinkable tape needs to be cut into a circular shape. This is because the cutting work is complicated and many parts must be discarded.

As shown in FIG. 5, with respect to the region T2c between the inner peripheral edge Fe of the annular frame F of the expanded sheet T2 and the outer peripheral edge Wd of the workpiece W, there is a constant interval in the circumferential direction of the workpiece W. Then, a plurality of rectangular heat shrink tapes T3 (for example, 18 sheets in total in the illustrated example) are attached in a ring shape. When the heat-shrinkable tape T3 has the property of being easily expanded and contracted in either the vertical or horizontal direction, it is preferable that the direction of easy expansion and contraction of the heat-shrinkable tape T3 and the radial direction of the workpiece W are matched.

Further, a plurality of rectangular heat-shrink tapes T3 (for example, 18 sheets in total) are attached to the region T2c of the expanded sheet T2 in a circumferential direction of the workpiece W at regular intervals, and then, Further, a plurality of heat-shrinkable tapes T3 (for example, 12 sheets in total) may be attached to the outer side in the radial direction in a circular shape.

(2) Chip interval forming step For example, after performing the heat shrink tape adhering step, the workpiece W supported by the annular frame F via the expanding sheet T2 is moved to the chip interval expanding device 5 shown in FIG. Transport to. The chip interval expansion device 5 is a device that can expand the interval between the chips C by expanding the expand sheet T2. The tip interval expanding device 5 includes, for example, an annular table 50 having an outer diameter larger than that of the expanding sheet T2, and the diameter of the opening 50c of the annular table 50 is smaller than the outer diameter of the expanding sheet T2. Has been done. On the outer peripheral portion of the annular table 50, for example, four (only two are shown in the figure) fixing clamps 52 are evenly arranged. The fixed clamp 52 is rotatable about a rotary shaft 52c by a spring (not shown) or the like, and the annular frame F and the expanded seat T2 are sandwiched between the holding surface 50a of the annular table 50 and the lower surface of the fixed clamp 52. be able to.

In the opening 50c of the annular table 50, a cylindrical expansion drum 53 is disposed with its height position fixed, and the center of the annular table 50 and the center of the expansion drum 53 are substantially aligned with each other. The outer diameter of the expansion drum 53 is smaller than the outer diameter of the expanded sheet T2 and larger than the outer diameter of the workpiece W.
On the inner peripheral side of the extension drum 53, a suction holding table 6 for holding the workpiece W by suction is arranged. The suction holding table 6 includes a suction unit 60 formed of a porous member and having a suction surface 600 on its upper surface, a frame body 61 that supports the suction unit 60, and a suction source 62 that transmits a suction force to the suction unit 60. ing. The suction surface 600 and the upper surface 610 of the frame 61 are formed so as to be flush with each other, and the suction force generated by the suction source 62 is transmitted to the suction surface 600, so that the suction surface 600 passes through the expanded sheet T2. The workpiece W can be held by suction.

The annular table 50 can be moved up and down in the Z-axis direction by, for example, an annular table elevating means 55. The annular table elevating/lowering means 55 is, for example, an air cylinder, has a bottomed cylindrical cylinder tube 550 having a piston (not shown) therein and having a bottom on the base end side (−Z direction side), and one end inserted into the cylinder tube 550. And a piston rod 551 attached to the piston. The other end of the piston rod 551 is fixed to the lower surface of the annular table 50. Air is supplied (or discharged) to the cylinder tube 550 and the pressure inside the cylinder tube 550 changes, so that the piston rod 551 moves in the Z-axis direction and the annular table 50 moves in the Z-axis direction.

In order to form a predetermined space between the chips C, for example, the annular frame F is placed on the holding surface 50a of the annular table 50 positioned at the reference height position via the expanding sheet T2. Next, the fixed clamp 52 is rotated so that the annular frame F and the expanded sheet T2 are sandwiched and fixed between the fixed clamp 52 and the holding surface 50a of the annular table 50. In this state, the holding surface 50a of the annular table 50 and the annular upper end surface of the expansion drum 53 are at the same height position, and the upper end surface of the expansion drum 53 is the inner peripheral edge Fe of the annular frame F of the expand sheet T2. The region T2c between the outer peripheral edge Wd of the workpiece W and the workpiece W is abutted from the base material surface side (the lower surface side in FIG. 6) of the expanded sheet T2. Further, the inner peripheral side of the region T2c on the base material surface side of the expanded sheet T2 is supported by the suction surface 600 and the upper surface 610, but suction holding is not performed on the suction surface 600.

As shown in FIG. 7, the annular table elevating means 55 lowers the annular table 50, in which the annular frame F and the expanded sheet T2 are sandwiched between the annular table 50 and the fixed clamp 52, in the −Z direction, so that the annular table 50 moves. The holding surface 50a is positioned at the expanded seat expansion position below the upper end surface of the expansion drum 53. As a result, the expansion drum 53 rises relatively to the fixed clamp 52, and the expanded sheet T2 is pushed up by the upper end surface of the expansion drum 53 and radially expanded outward in the radial direction. The heat shrink tape T3 is also expanded by the adhesive force of the expanding sheet T2 and the tension applied in the horizontal direction. Then, as the expanded sheet T2 is expanded, a predetermined space V is formed between the chips C. It should be noted that the size of the interval V is a size that can be appropriately changed depending on the lowered position of the annular table 50.

The step of attaching the heat-shrinkable tape may be performed, for example, after the step of forming the chip interval.

(3) Expanding Sheet Shrinking Step After the predetermined distance V is formed between the chips, the suction source 62 and the suction portion 60 are communicated with each other to apply suction to the suction surface 600, so that the area T2c of the expanded sheet T2 is reduced. Hold the peripheral side by suction. Then, as shown in FIG. 8, for example, the annular table elevating means 55 moves the annular table 50 +Z so that the holding surface 50a of the annular table 50 and the annular upper end surface of the expansion drum 53 are at the same height position. When it is lifted in the direction, the force for pulling the expanded sheet T2 in the horizontal direction is lost, and the tension of the expanded sheet T2 is released. Along with this, the region T2c between the inner peripheral edge Fe of the annular frame F of the expanded sheet T2 and the outer peripheral edge Wd of the workpiece W extends and becomes loose. Therefore, the area T2c of the expanded sheet T2 is heated together with the heat shrink tape T3 by the heating means 7 shown in FIG.

The heating means 7 is, for example, an infrared heater capable of emitting infrared rays, and heats the area T2c of the heat shrink tape T3 and the expanding sheet T2 from above without contact. The heating means 7 may be a contact type or a hot air heater capable of injecting hot air from a nozzle. The heat shrinkage tape T3 has a large heat shrinkage rate, and since the heat shrinkage tape T3 is expanded in the chip interval forming step, the heat shrinkage tape T3 is heated by the heating means 7 to be directed inward in the radial direction to a size before expansion, for example. Contract. The expanded sheet T2 undergoes almost no thermal shrinkage due to heating by the heating means 7, but the shrinkage force of the heat-shrinkable tape T3 propagates as a mechanical external force to the region T2c of the expandable sheet T2 to which the heat-shrinkable tape T3 is attached. Therefore, the slackened region T2c of the expanded sheet T2 is pulled inward in the radial direction and contracts to the state before expansion. Further, since the heating by the heating means 7 is performed only on the heat shrink tape T3 and the region T2c of the expanded sheet T2, the interval V between the adjacent chips C can be maintained at the size after expansion. Furthermore, since the inner peripheral side of the region T2c is suction-held by the suction surface 600, the chips C do not move, and the interval V between the adjacent chips C can be reliably maintained.

After the expansion sheet contraction step is completed, the plurality of chips C supported by the annular frame F via the expansion sheet T2 are conveyed to the pickup device (not shown), but the interval V between the chips C is expanded. Since the state is maintained and the expanded sheet T2 has returned to the state of being attached to the annular frame F while being stretched without slack, the chips C come into contact with each other when the workpiece W is handled through the annular frame F. Can be prevented from being damaged.

The tip spacing maintaining method according to the present invention is not limited to the above-described embodiment, and the laser processing apparatus 1, the grinding apparatus 2, and the tip spacing expanding apparatus 5 shown in the accompanying drawings have the same configuration. However, the present invention is not limited to this, and can be appropriately changed within a range where the effects of the present invention can be exhibited.

For example, in the present embodiment, after the modified layer M is formed on the work W by the laser processing device 1, the work W is ground and divided by the grinding device 2. Instead of grinding by the grinding device 2, the expanding tape T2 may be expanded by the chip interval expanding device 5 to divide the workpiece W, and at the same time, a predetermined interval may be formed between the chips.

Further, the workpiece W may be divided without using the laser processing device 1. That is, first, a cutting device having a rotatable cutting blade performs a cutting process on the workpiece W from the front surface Wa side along the planned dividing line S to form a machining groove of a predetermined depth on the workpiece W. After the formation, the workpiece W may be divided into chips by grinding the workpiece W from the back surface Wb side to a height position where the bottom of the processed groove is exposed. Thereafter, the expanding tape T2 may be expanded by the chip interval expanding device 5 to form a predetermined interval between the chips.

W: Workpiece Wa: Surface of Workpiece Wb: Backside of Workpiece S: Divided Line D: Device M: Modified Layer C: Chip
T1: Protective tape T1a: Adhesive surface of protective tape
T2: Expanded sheet T2a: Adhesive surface of expanded sheet T2b: Base surface of expanded sheet T3: Heat shrink tape 1: Laser processing device 10: Chuck table 10a: Holding surface of chuck table 11: Laser light irradiation means 111: Focus Device 112: Condensing lens
12: Processing feeding means 14: Alignment means 140: Infrared camera 2: Grinding device 20: Holding table 20a: Holding surface of holding table 23: Y-axis direction feeding means 21: Grinding means 210: Rotating shaft 212: Motor 213: Mount
214: Grinding wheel 214a: Wheel base 214b: Grinding grindstone 5: Tip interval expanding device 50: Annular table 50a: Holding surface of annular table 50c: Opening of annular table 52: Fixed clamp 53: Expansion drum 55: Annular table lifting means 550: Cylinder tube 551: Piston rod 6: Suction holding table 60: Suction part 600: Suction surface 61: Frame body 610: Upper surface 62: Suction source 7: Heating device

Claims (1)

A chip interval maintaining method for maintaining an expanded interval of a plurality of chips constituting a workpiece supported by an annular frame through the expand sheet in a state of being attached to an expand sheet,
While fixing the expandable sheet on the holding surface of the annular table, the expandable sheet is supported by the suction surface of the suction holding table disposed on the inner peripheral side of the annular table in a state where it is not sucked and held, and A chip interval forming step of moving the suction surface relative to each other in the vertical direction to expand the expand sheet to form an interval between the chips;
After performing the chip interval forming step, the region corresponding to the chip of the expand sheet is suction-held by the suction surface of the suction-holding table and the space between the chips is maintained while maintaining the space between the chips and the inner peripheral edge of the annular frame. An expand sheet contracting step of heating the expand sheet between the outer peripheral edge of the workpiece and contracting the expanded sheet stretched on the outer peripheral side of the workpiece,
Before carrying out at least the expand sheet shrinking step, a heat shrink tape attaching step of attaching a plurality of rectangular heat shrink tapes to the expand sheet between the inner peripheral edge of the annular frame and the outer peripheral edge of the workpiece is performed. Further preparation,
In the step of shrinking the expanded sheet, the expanded sheet between the inner peripheral edge of the annular frame and the outer peripheral edge of the workpiece is heated together with the heat shrinkable tape to shrink the expandable sheet in the area where the heat shrinkable tape is attached. How to maintain the chip interval.

Images