JP7634152B2 - Workpiece dividing device - Google Patents

Description

The present invention relates to a workpiece dividing device and a workpiece dividing method, and in particular to a workpiece dividing device and a workpiece dividing method for dividing a workpiece such as a semiconductor wafer into individual chips along a planned division line.

Conventionally, in the manufacture of semiconductor chips (hereafter referred to as chips), a workpiece dividing device is known that divides a semiconductor wafer (hereafter referred to as wafer) into individual chips along the dividing lines, the wafer having dividing lines formed therein in advance by half-cutting with a dicing blade or forming modified regions by laser irradiation (see Patent Document 1, etc.).

Figure 12 is an explanatory diagram of a wafer unit 2 to which a disk-shaped wafer 1 to be divided by a workpiece dividing device is attached, with Figure 12(A) being a perspective view of the wafer unit 2 and Figure 12(B) being a vertical cross-sectional view of the wafer unit 2.

The wafer 1 is attached to the center of a dicing tape (also called an expansion tape or adhesive sheet) 3 that is approximately 100 μm thick and has an adhesive layer formed on one side, and the dicing tape 3 is fixed at its outer periphery to a rigid ring-shaped frame 4.

In the workpiece dividing device, the frame 4 of the wafer unit 2 is fixed by abutting against a frame fixing member (also called a frame fixing mechanism) 7 shown by a two-dot chain line. After this, an expand ring (also called a push-up ring) 8 shown by a two-dot chain line is moved upward from below the wafer unit 2, and the dicing tape 3 is pressed by this expand ring 8 to expand radially. The tension of the dicing tape 3 generated at this time is applied to the division lines 5 of the wafer 1, dividing the wafer 1 into individual chips 6. The division lines 5 are formed in the X direction and the Y direction, which are perpendicular to each other. When the number of division lines 5 parallel to the X direction and the number of lines parallel to the Y direction are the same and the intervals in each direction are equal, the divided chips 6 have a square shape. When the number of lines parallel to the X direction and the number of lines parallel to the Y direction are different and the intervals in each direction are equal, the divided chips 6 have a rectangular shape.

The dicing tape 3 is a flexible material with a low Young's modulus. Therefore, in order to smoothly divide the wafer 1 into individual chips 6, it is possible to expand the dicing tape 3 by cooling it and increasing its spring constant.

The tape expansion device (workpiece dividing device) of Patent Document 2 is equipped with a cold air supplying means. According to Patent Document 2, the cold air supplying means is operated to supply cold air into the processing space, and the processing space is cooled to, for example, 0°C or less, thereby cooling the dicing tape.

On the other hand, the chip division and separation device (work division device) of Patent Document 3 focuses on the anisotropy of the dicing tape and is equipped with a film surface support mechanism to uniformly expand the dicing tape while taking into account the anisotropy. This film surface support mechanism is equipped with multiple support mechanisms that are independent in the circumferential direction, and the relative heights of the multiple support mechanisms are individually controlled to adjust the tension of the dicing tape, thereby independently controlling the elongation of the dicing tape in the X direction and the Y direction.

In this specification, the circular area of the dicing tape 3 to which the wafer 1 is attached is referred to as the central area 3A, the doughnut-shaped area between the outer edge of the central area 3A (the outer edge of the wafer 1) and the inner edge of the frame 4 is referred to as the annular area 3B, and the doughnut-shaped area of the outermost periphery fixed to the frame 4 is referred to as the fixed area 3C. The annular area 3B is the area that is expanded by being pressed against the expand ring 8.

It is known that the force required to divide the wafer 1, i.e., the tension that must be generated in the annular region 3B to divide the wafer 1, must be higher as the number of planned division lines 5 increases. Regarding the number of planned division lines 5, for example, when the chip size is 5 mm on a wafer 1 with a diameter of 300 mm, approximately 120 planned division lines 5 (60 in each of the X and Y directions) are formed, and when the chip size is 1 mm, approximately 600 planned division lines 5 are formed. Therefore, the tension that must be generated in the annular region 3B must be higher as the chip size becomes smaller.

On the other hand, in the field of workpiece dividing devices, it is also required to prevent deterioration of chip quality caused by contact between chips after division by maintaining the expanded state of the dicing tape expanded by the expanding ring.

As a work division device that satisfies this requirement, Patent Document 4 discloses a work division device equipped with a sub-ring. The sub-ring of Patent Document 4 has the function of holding the dicing tape expanded by the expand ring in an expanded state, and is configured with a diameter larger than the inner diameter of the frame. The sub-ring is inserted between the outer periphery of the dicing tape and the surface of the frame immediately after it is raised from the back side of the dicing tape toward the dicing tape and passes through the frame. This maintains the expanded state of the dicing tape even after the expansion of the dicing tape by the expand ring has ended. By maintaining the expanded state of the dicing tape in this way, it is possible to prevent the dicing tape from loosening, thereby preventing a deterioration in the quality of the chips due to contact between the chips.

JP 2016-149581 A JP 2016-12585 A Patent No. 5912274 JP 2013-51368 A

The inner diameter (diameter of the inner edge of the frame) of the frame 4 on which the 300 mm diameter wafer 1 is mounted is set to 350 mm according to the SEMI standard (G74-0699 Specifications for Tape Frames for 300 mm Wafers). According to this standard, as shown in the vertical cross-sectional view of the wafer unit 2 in FIG. 13, an annular region 3B with a width of 25 mm exists between the outer edge of the wafer 1 and the inner edge of the frame 4. As shown in the vertical cross-sectional views of the main parts of the workpiece dividing device shown in FIGS. 14(A) and (B), the frame fixing member 7 that fixes the frame 4 is installed at a position spaced outward from the annular region 3B in the in-plane direction of the dicing tape 3 indicated by the arrow A so as not to come into contact with the annular region 3B expanded by the expand ring 8.

Therefore, the force that divides the wafer 1 generated by the upward movement of the expand ring 8 is decomposed into three forces: (i) a force that expands the entire area of the annular region 3B, (ii) a force that divides the wafer 1 into chips 6, and (iii) a force that expands the dicing tape 3 between adjacent chips 6.

As shown in the operation diagram of the workpiece dividing device in Figures 15(A) to (E), when the expand ring 8 comes into contact with the annular region 3B of the dicing tape 3 and the dicing tape 3 begins to expand due to the rising movement of the expand ring 8 (Figure 15(A)), the annular region 3B, which has the lowest spring constant, begins to expand first (Figure 15(B)). This generates tension in the annular region 3B, and when this tension increases to a certain extent, the increased tension is transmitted to the wafer 1, and the division of the wafer 1 into chips 6 begins (Figure 15(C)). When the wafer 1 is divided into individual chips 6, the expansion of the annular region 3B and the expansion of the dicing tape 3 between the chips proceed simultaneously (Figures 15(D) to (E)).

In the conventional workpiece dividing device, when a wafer 1 having a diameter of 300 mm has a chip size of 5 mm or more, the tension generated in the annular region 3B can divide the wafer 1 into individual chips 6 without any problems. However, as the circuit patterns formed on the wafer 1 become finer, chips with smaller chip sizes of 1 mm or less have also appeared. In this case, the force required to divide the wafer 1 increases due to an increase in the number of division lines 5 that divide the wafer 1, and sometimes a force greater than the tension caused by the expansion of the annular region 3B is required. This causes a problem that, as shown in the vertical cross-sectional view of the wafer unit 2 in Figure 16, even after the expansion operation by the expand ring 8 is completed, some of the division lines 5 formed on the wafer 1 remain undivided.

This problem of the planned division line 5 not being divided cannot be solved even if the expansion amount or expansion speed of the dicing tape 3 is increased. For example, if the expansion amount of the dicing tape 3 is increased, the annular region 3B begins to undergo plastic deformation. Since the spring constant of the annular region 3B during plastic deformation is smaller than the spring constant during elastic deformation, no tension is generated to divide the wafer 1 into individual chips 6 in the region of the annular region 3B that exceeds the elastic deformation. On the other hand, even if the expansion speed of the dicing tape 3 is increased, a part of the annular region 3B begins to undergo plastic deformation, so no tension is generated to divide the wafer 1 into individual chips 6. This is because the frequency response of the dicing tape 3 is low, so the force is not transmitted to the entire dicing tape 3 without time lag.

In order to solve the problem of unseparated planned division lines 5, Patent Document 2 addresses this by cooling the dicing tape and increasing the spring constant of the dicing tape, but this is not effective enough for the small chips of 1 mm or less that are common in recent years.

In addition, the chip separation device in Patent Document 3 can independently control the stretching of the dicing tape in the X and Y directions, but cannot apply a force to the wafer greater than the tension caused by the expansion of the annular region, and therefore cannot solve the problem of the planned separation lines not being separated.

In addition, the work division devices of Patent Documents 1 to 3 do not have a sub-ring like Patent Document 4, so there is a risk of the problem of reduced chip quality caused by contact between chips after division. As such, there is no conventional work division device that can resolve the problem of non-division of the planned division line that occurs when the chip size is small, while also resolving the problem of reduced chip quality caused by contact between chips after division, and there has been a demand for the realization of such a device.

The present invention was made in consideration of these problems, and aims to provide a work division device and a work division method that can simultaneously solve the problem of non-division of the planned division line that occurs when the chip size is small, and the problem of reduced chip quality caused by contact between chips after division.

In order to achieve the object of the present invention, the workpiece dividing device of the present invention is a workpiece dividing device in which the outer periphery of a dicing tape is fixed to a ring-shaped frame having an inner diameter larger than the outer diameter of the workpiece, and the workpiece attached to the dicing tape is divided into individual chips along a planned division line, the workpiece dividing device comprising: an expand ring arranged on the back side opposite the dicing tape surface on which the workpiece is attached, and having an opening smaller than the inner diameter of the frame and larger than the outer diameter of the workpiece; the expand ring is moved in a direction approaching the dicing tape relatively to press and expand the dicing tape; and an expand ring arranged on the same side as the dicing tape surface on which the workpiece is attached, and having an opening smaller than the inner diameter of the frame and larger than the outer diameter of the expand ring. The device is provided with an expansion restriction ring formed in a ring shape having an expansion restriction ring that contacts the dicing tape when the dicing tape is expanded and restricts the expansion of an outer peripheral region located on the outer side of the contact portion of the dicing tape that contacts the expansion restriction ring; an expansion restriction ring moving mechanism that moves the expansion restriction ring away from the position where it restricts the expansion of the outer peripheral region; and an expansion retention ring formed in a ring shape having an elastically deformable fitting portion that is larger than the inner diameter of the frame and that is disposed on the back side of the dicing tape opposite the work attachment surface, and that retains the expanded state of the dicing tape by having the fitting portion fit into the surface of the frame after the expansion restriction ring is moved away from the position where it restricts the expansion of the outer peripheral region by the expansion restriction ring moving mechanism.

According to the workpiece dividing device of the present invention, when the expanding ring is moved in a direction approaching the dicing tape relatively with the expanding ring positioned at a position that restricts the expansion of the outer peripheral region, and the dicing tape is pressed by the expanding ring to start expanding the dicing tape, the dicing tape comes into contact with the expanding restricting ring during the expansion of the dicing tape. At this time, the dicing tape is divided into an outer peripheral region located on the outer periphery side and an inner peripheral region located on the inner periphery side, with the contact portion contacting the expanding restricting ring as a boundary. Then, in the expanding operation by the expanding ring after the dicing tape comes into contact with the expanding restricting ring, only the inner peripheral region expands while the expansion of the outer peripheral region is restricted by the expanding restricting ring. In other words, the tension of the spring constant of the inner peripheral region, which is larger than the spring constant of the dicing tape, is applied to the workpiece. As a result, the tension applied to the workpiece increases, and the problem of non-division of the planned division line that occurs when the chip size is a small chip can be solved. Then, when the chip division is completed, the expansion restriction ring is moved away from the position restricting the expansion of the outer peripheral region by the expansion retention ring movement mechanism, and then the fitting portion of the expansion retention ring is fitted to the surface of the frame to maintain the expanded state of the dicing tape. In this way, according to the present invention, it is possible to simultaneously solve the problem of non-division of the intended division line that occurs when the chip size is small, and the problem of deterioration of chip quality due to contact between chips after division.

One aspect of the present invention has a frame fixing member that fixes the frame, and it is preferable that the expansion restriction ring is removably fixed to the frame fixing member at a position that restricts the expansion of the outer peripheral region.

According to this embodiment, by fixing the expansion restriction ring to the frame fixing member, the expansion restriction ring can be reliably fixed at a position that restricts the expansion of the outer peripheral region, so that the expansion of the dicing tape can be reliably restricted.

In one aspect of the present invention, the frame fixing member is preferably configured in a ring shape with an opening larger than the inner diameter of the frame, and the expansion restriction ring is preferably attached to the inner peripheral surface of the opening of the frame fixing member.

According to one aspect of the present invention, a position expansion restriction ring can be attached in an appropriate position to restrict the expansion of the outer peripheral region.

In one aspect of the present invention, it is preferable that the frame fixing member is provided with a fixing member that detachably fixes the expansion restriction ring.

According to one aspect of the present invention, the expansion restriction ring can be fixed to the frame fixing member by a fixing member.

In order to achieve the object of the present invention, the workpiece dividing method of the present invention comprises fixing the outer periphery of a dicing tape to a ring-shaped frame having an inner diameter larger than the outer diameter of the workpiece, and dividing the workpiece attached to the dicing tape into individual chips along a planned dividing line. In this method, an expand ring arranged on the back side of the dicing tape opposite to the surface on which the workpiece is attached is moved in a direction approaching the dicing tape relatively, so that the annular region of the dicing tape between the outer edge of the workpiece and the inner edge of the frame is pressed by the expand ring, thereby dividing the dicing tape into individual chips along a planned dividing line. The method includes an expansion process for expanding the dicing tape, an expansion restriction ring arranged on the same side of the dicing tape as the work attachment surface, an expansion restriction process for restricting the expansion of the outer peripheral region located on the outer side of the contact portion of the annular region that is in contact with the expansion restriction ring, and an expansion state retention process for retaining the expanded state of the dicing tape expanded by the expansion process with the expansion retention ring by contacting the expansion restriction ring with an expansion restriction ring at a position outside the annular region of the dicing tape when the expansion restriction ring is pressed.

The workpiece division method of the present invention can simultaneously solve the problem of non-division of the planned division line that occurs when the chip size is small, and the problem of reduced chip quality caused by contact between chips after division.

In one aspect of the present invention, it is preferable that after the expansion step, an expansion restriction ring retraction step is performed, and after the expansion restriction ring retraction step, an expansion state maintenance step is performed.

In one aspect of the present invention, an expansion retaining ring is disposed on the back side of the dicing tape opposite the work attachment surface, and the expanded state retaining step preferably involves moving the expansion retaining ring in a direction approaching the dicing tape relatively, thereby retaining the expanded state of the dicing tape by engaging an elastically deformable fitting portion formed on the outer periphery of the expansion retaining ring with the surface of the frame.

The present invention can simultaneously solve the problem of non-division of the planned division lines that occurs when the chip size is small, and the problem of deterioration of chip quality due to contact between chips after division.

A structural diagram of a main part of a dividing stage of a workpiece dividing device according to an embodiment. FIG. 2 is an enlarged perspective view of a main part of the split stage shown in FIG. FIG. 1 is a cross-sectional view of a wafer unit showing the shape of the annular region during expansion. A vertical cross-sectional view showing the expansion state of the dicing tape by the expansion retaining ring. FIG. 5 is an enlarged cross-sectional view of a main part of FIG. Block diagram showing the control system of the workpiece dividing device 1 is a flowchart showing an example of a wafer dividing method. Operational diagram of the workpiece dividing device Operational diagram of the workpiece dividing device A graph showing the expansion rate of the annular region and the inner peripheral region when an expansion restriction ring is used and when it is not used. A graph showing the chip split ratio with and without the extended regulation ring. An explanatory diagram of a wafer unit with a wafer attached Vertical cross-sectional view of the wafer unit Side view of the main part of the workpiece dividing device Operation diagram of the workpiece dividing device A longitudinal sectional view of a wafer unit into which wafers are separated.

Below, preferred embodiments of the workpiece dividing device and workpiece dividing method according to the present invention will be described in detail with reference to the attached drawings. The present invention is not limited to the following embodiments, and various modifications and substitutions can be made to the following embodiments within the scope of the present invention.

Figure 1 is a vertical cross-sectional view of the main part of a dividing stage provided in a work dividing device 10 according to an embodiment, and Figure 2 is an enlarged perspective view of the main part of the dividing stage. Note that the size of the wafer unit divided by the work dividing device 10 is not limited, but in the embodiment, a wafer unit 2 on which a wafer 1 with a diameter of 300 mm is mounted is shown as an example, as shown in Figure 13.

As shown in FIG. 2, the workpiece dividing device 10 is a device that divides a wafer 1 on which planned dividing lines 5 are formed into individual chips 6 along the planned dividing lines 5. A plurality of planned dividing lines 5 are formed in the X direction and the Y direction which are perpendicular to each other. In the embodiment, a wafer 1 having 300 planned dividing lines 5 parallel to the X direction and 300 planned dividing lines 5 parallel to the Y direction, each spaced equally apart, i.e., a wafer 1 to be divided into chips 6 with a chip size of 1 mm, is illustrated.

As shown in Figures 1 and 2, the wafer 1 is attached to the center of the dicing tape 3, the outer periphery of which is fixed to the frame 4. The dicing tape 3 has a central region 3A that is circular in plan view to which the wafer 1 is attached, and an annular region 3B that is doughnut-shaped in plan view between the outer edge of the central region 3A (the outer edge of the wafer 1) and the inner edge of the frame 4.

The thickness of the wafer 1 is, for example, about 50 μm. For the dicing tape 3, for example, a PVC (polyvinyl chloride) tape is used. The wafer 1 may be attached to the dicing tape 3 via a film-like adhesive such as DAF (Die Attach Film). For example, a PO (polyolefin)-based film-like adhesive may be used.

The workpiece dividing device 10 includes a frame fixing member 7 (see Figures 14 and 15) that fixes the frame 4, an expansion ring 14 that abuts against the annular region 3B of the dicing tape 3 from below and presses and expands the dicing tape 3, an expansion restriction ring 16 that abuts against the dicing tape 3 when the dicing tape 3 is expanded by the expansion ring 14, and an expansion retention ring 18 that maintains the expanded state of the dicing tape 3 expanded by the expansion ring 14.

The frame fixing member 7 is disposed on the same side of the dicing tape 3 as the attachment surface of the wafer 1, and the frame 4 is fixed to its underside 7A. The frame fixing member 7 is also disposed at a position spaced outward from the annular region 3B in the in-plane direction of the dicing tape 3 indicated by the arrow A so as not to come into contact with the annular region 3B expanded by the expand ring 14.

As shown in FIG. 2, the shape of the frame fixing member 7 is a ring having an opening 7B with a diameter of, for example, 361 mm, which is larger than the inner diameter (350 mm) of the frame 4, but the shape is not particularly limited. The frame fixing member 7 can be, for example, a rectangular plate material having an opening 7B, or a frame fixing member consisting of multiple fixing members arranged at a predetermined interval along the outer periphery of the frame 4. The inscribed circles of these fixing members are set equal to the diameter of the opening 7B.

The expand ring 14 is disposed on the back side of the dicing tape 3 opposite to the attachment surface of the wafer 1, and is formed in a ring shape with an expansion opening (opening) 14A that is smaller than the inner diameter (350 mm) of the frame 4 and larger than the outer diameter (300 mm) of the wafer 1. The expand ring 14 is disposed so as to be movable in a direction approaching the dicing tape 3 relatively. Specifically, the expand ring 14 is disposed so as to be movable in the vertical direction between an expansion position (position shown by the two-dot chain line in FIG. 1) where the expand ring 14 presses the back side of the annular region 3B of the dicing tape 3 to expand the annular region 3B, and a retracted position (position shown by the solid line in FIG. 1) where the expand ring 14 is retracted downward from the expansion position.

The workpiece dividing device 10 is also provided with an expand ring moving mechanism 20 that moves the expand ring 14 up and down between the expanded position and the retracted position. A feed screw device is illustrated as an example of the expand ring moving mechanism 20, but an actuator such as an air cylinder device can be used instead. When the expand ring 14 located in the retracted position is moved toward the expanded position by the expand ring moving mechanism 20, the expand ring 14 is moved upward in the direction of arrow B toward the annular region 3B. As a result, the back surface of the annular region 3B is pressed against the expand ring 14 and radially expanded. Note that the annular region 3B may be pressed by the expand ring 14 by fixing the expand ring 14 and moving the wafer unit 2 downward in the direction of arrow C. When the annular region 3B is expanded by the expand ring 14, it abuts against the expansion restriction ring 16.

The expansion restriction ring 16 is arranged on the same side of the dicing tape 3 as the attachment surface of the wafer 1, and is formed in a ring shape with an expansion restriction opening (opening) 16A that is smaller than the inner diameter (350 mm) of the frame 4 and larger than the outer diameter of the expand ring 14.

The expansion restriction ring 16 is arranged to be movable up and down between an expansion restriction position (a position restricting the expansion of the outer peripheral region 3E: a position shown by a solid line in FIG. 1) where the dicing tape 3 comes into contact when the dicing tape 3 expands, and a retreated position (a position shown by a two-dot chain line in FIG. 1) retreated upward from the expansion restriction position. The outer peripheral region 3E will be described later.

The workpiece dividing device 10 is also provided with an expansion restriction ring moving mechanism 22 that moves the expansion restriction ring 16 between the expansion restriction position and the retracted position. An air cylinder device is shown as an example of the expansion restriction ring moving mechanism 22, but an actuator such as a feed screw device can also be used instead.

In addition, it is preferable that the expansion restriction ring 16 is detachably attached to the inner peripheral surface of the opening 7B of the frame fixing member 7 in the expansion restriction position. This allows the expansion restriction ring 16 to be attached to an appropriate position that restricts the expansion of the outer peripheral region 3E. In addition, the expansion restriction ring 16 is fixed to the frame fixing member 7 by a fixing member in the expansion restriction position. The fixing member is not particularly limited, but an example is a fixing member using multiple pins 24. This fixing member arranges the pins 24 on the inner peripheral surface of the opening 7B so that they can be freely protruded and retracted, and forms a hole 26 on the outer peripheral surface of the expansion restriction ring 16 into which the protruding pins 24 fit. In other words, according to this fixing member, when the expansion restriction ring 16 is attached to the inner peripheral surface of the opening 7B, the pins 24 protrude from the frame fixing member 7 and fit into the hole 26 of the expansion restriction ring 16. This allows the expansion restriction ring 16 to be fixed to the inner peripheral surface of the opening 7B of the frame fixing member 7. The fixed position of the expansion restriction ring 16 relative to the frame fixing member 7 is not limited to the inner peripheral surface of the opening 7B, but may be any position that can adequately restrict the expansion of the outer peripheral region 3E, and may be, for example, the surface of the frame fixing member 7.

Here, the frame fixing member 7 is fixed to a fixed structure of the work division device 10. As a result, the expansion restriction ring 16, which is positioned at the expansion restriction position and fixed to the frame fixing member 7 via the pin 24, is securely fixed at the expansion restriction position. As shown in FIG. 3 described later, when the dicing tape 3 expands, the annular region 3B abuts against the expansion restriction ring 16, and the expansion of the outer peripheral region 3E is restricted by the expansion restriction ring 16. For this reason, the expansion restriction ring 16 receives a force from the annular region 3B. At this time, if the expansion restriction ring 16 is displaced upward by the force from the annular region 3B, it becomes impossible to properly restrict the expansion of the outer peripheral region 3E. However, in the embodiment, since the expansion restriction ring 16 is securely fixed to the frame fixing member 7 via the pin 24 at the expansion restriction position, it is possible to prevent displacement due to the force from the annular region 3B, and it is possible to properly restrict the expansion of the outer peripheral region 3E. It should be noted that the expansion restriction ring 16 may be fixed in the expansion restriction position by a fixing member (not shown) instead of fixing the expansion restriction ring 16 to the frame fixing member 7 by the pin 24, which is a fixing member.

Figure 3 is a vertical cross-sectional view of the wafer unit 2 showing the shape of the annular region 3B during expansion by the expansion ring 14.

As shown in FIG. 3, when the annular region 3B is expanded by the expand ring 14, the annular region 3B abuts against the expansion restriction ring 16. Specifically, the annular region 3B abuts against the inner edge 16B on the back side of the expansion restriction ring 16. In other words, the expansion restriction ring 16 abuts against a position of the annular region 3B that is outside the pressing position of the expand ring 14.

In this embodiment, as shown in FIG. 1, the diameter of the expansion restriction opening 16A is set to 338 mm. As a result, the width dimension of the outer peripheral region 3E, whose expansion is restricted by the expansion restriction ring 16, is set to 6 mm, and the width dimension of the inner peripheral region 3F of the annular region 3B excluding the outer peripheral region 3E is set to 19 mm.

Here, the inner peripheral region 3F of the annular region 3B, whose expansion is not restricted by the expansion restriction ring 16, is the region that substantially contributes to the division of the wafer 1. In other words, as the width dimension of the inner peripheral region 3F is reduced, the spring constant of the inner peripheral region 3F increases, so that the tension applied to the wafer 1 from the inner peripheral region 3F can be increased. Therefore, it is preferable to set the width dimension of the inner peripheral region 3F according to the division conditions defined by the number of planned division lines 5, etc.

The expansion retaining ring 18, which maintains the expanded state of the dicing tape 3, is placed on the back side of the dicing tape opposite the surface to which the wafer 1 is attached. The expansion retaining ring 18 also has a main ring 28 whose outer diameter is smaller than the inner diameter (350 mm) of the frame 4 and larger than the outer diameter of the expand ring 14, and an elastically deformable ring-shaped fitting portion 30 that is attached to the outer periphery of the main ring 28 and has an outer diameter (351.3 mm) larger than the inner diameter (350 mm) of the frame 4.

Figure 4 is a vertical cross-sectional view of the dicing tape 3 in an expanded state maintained by the expansion retaining ring 18. Figure 5 is an enlarged cross-sectional view of a main portion of Figure 4.

As shown in Figures 4 and 5, the fitting portion 30 of the expansion retaining ring 18 fits onto the surface 4A of the frame 4 through the annular region 3B of the dicing tape 3 at the fitting position shown by the solid line. This allows the expansion state of the dicing tape 3 to be maintained by the expansion retaining ring 18.

Before expansion and holding, the expansion retaining ring 18 is in a standby position (position shown by a solid line in FIG. 1) below the engagement position shown by the solid lines in FIG. 4 and FIG. 5, and is moved upward from the standby position to the engagement position by the expansion retaining ring moving mechanism 32 during expansion and holding. A feed screw device is illustrated as an example of the expansion retaining ring moving mechanism 32, but an actuator such as an air cylinder device can be used instead. When the expansion retaining ring 18 is raised by the expansion retaining ring moving mechanism 32, the engagement portion 30 abuts against the lower surface of the frame 4, and then the engagement portion 30 is pushed against the inner surface of the frame 4 and rises while elastically deforming, and the rise of the expansion retaining ring 18 is stopped at the position where the engagement portion 30 passes through the inner surface of the frame 4. As a result, the engagement portion 30 is engaged with the surface 4A of the frame 4 at the engagement position as shown in FIG. 4 and FIG. The expansion retaining ring 18 may be fixed and the dicing tape 3 side may be moved in a direction approaching the expansion retaining ring 18. That is, the expansion retaining ring 18 is moved in a direction relatively closer to the dicing tape 3 so that the fitting portion 30 fits onto the surface 4A of the frame 4.

The operation of the expansion ring moving mechanism 20 that drives the expansion ring 14, the expansion restricting ring moving mechanism 22 that drives the expansion restricting ring 16, and the expansion retaining ring moving mechanism 32 that drives the expansion retaining ring 18 is controlled by a control unit 34 that provides overall control of the work division device 10, as shown in the block diagram of the control system in Figure 6.

An example of a work division method using the control unit 34 is described below.

First, the control unit 34 controls the expansion restriction ring moving mechanism 22 to position the expansion restriction ring 16 in the expansion restriction position, and then controls the expand ring moving mechanism 20 to move the expand ring 14 to the expansion position. Next, the control unit 34 controls the expansion restriction ring moving mechanism 22 to move the expansion restriction ring 16 to the retracted position. Next, the control unit 34 controls the expansion retaining ring moving mechanism 32 to move the expansion retaining ring 18 to the mating position. Next, the control unit 34 controls the expand ring moving mechanism 20 to move the expand ring 14 to the retracted position.

Next, the above-mentioned work division method will be specifically explained according to the flowchart in FIG. 7 and the operation explanatory diagrams of the work division device 10 shown in FIGS. 8(A)-(D) and 9(E)-(H).

First, in the placement process of step S100 in FIG. 7, as shown in FIG. 8(A), the expand ring 14 is placed in the retracted position by the expand ring moving mechanism 20, the expansion restricting ring 16 is placed in the expanded restricting position by the expansion restricting ring moving mechanism 22, and the expansion retaining ring 18 is placed in the standby position by the expansion retaining ring moving mechanism 32. At this time, the expansion restricting ring 16 is fixed to the frame fixing member 7 via the pin 24.

Next, in the fixing process of step S110 in FIG. 7, the frame 4 of the wafer unit 2 is fixed to the frame fixing member 7 as shown in FIG. 8 (B).

Next, in the expansion start process of step S120 in FIG. 7, as shown in FIG. 8(C), the expand ring moving mechanism 20 moves the expand ring 14 upward in the direction of arrow B from the retracted position in FIG. 8(A) to the expanded position, starting the expansion of the entire area of the annular region 3B. Note that the annular region 3B may be cooled to a low temperature in advance by a cooling means (not shown) to increase the spring constant of the annular region 3B in advance. Examples of the cooling means include a contact type that cools the annular region 3B by contacting it, or an air-cooling type that cools the annular region 3B by spraying cold air onto it.

Next, in the expansion restriction process of step S130 in FIG. 7, when the upward movement of the expand ring 14 exceeds the thickness of the frame 4, as shown in FIG. 8 (D), the annular region 3B abuts against the expansion restriction ring 16. At this time, as shown in FIG. 3, the annular region 3B is divided into an outer peripheral region 3E located on the outer periphery side and an inner peripheral region 3F located on the inner periphery side, with the abutment portion 3D abutting against the inner edge portion 16B of the expansion restriction ring 16 as the boundary. Then, the expansion of the outer peripheral region 3E of the annular region 3B is restricted by the expansion restriction ring 16. The expansion restriction process of S130 is a process that is performed when the expansion process from the expansion start process of S120 to the division process of S140 is performed. In other words, the expansion process is fixed and includes the expansion start process of S120, the expansion restriction process of S130, and the division process of S140.

Next, in the division process of step S140 in FIG. 7, as shown in FIG. 9(E), the upward movement of the expand ring 14 continues, and the wafer 1 is divided into individual chips 6 by continuing to expand the inner peripheral region 3F of the annular region 3B, excluding the outer peripheral region 3E in FIG. 3. After this, when the expand ring 14 reaches the expansion position, the upward movement of the expand ring 14 is stopped. In other words, the expansion and fixation is completed at this point.

In the division step S140, when the annular region 3B comes into contact with the inner edge 16B of the expansion restriction ring 16, the expansion ring 14 expands only the inner region 3F while the expansion of the outer region 3E is restricted by the expansion restriction ring 16. In other words, the tension of the spring constant of the inner region 3F, which is greater than the spring constant of the annular region 3B, is applied to the wafer 1.

To be more specific, the length of the annular region 3B that contributes to the division of the wafer 1 is shortened from 25 mm (width of the annular region 3B) to 19 mm (width of the inner region 3F), and the spring constant increases inversely proportionally. As a result, even if only the inner region 3F is expanded, the spring constant of the inner region 3F is greater than the spring constant of the annular region 3B, so that it is possible to apply tension to the wafer 1 sufficient to divide it into individual chips 6 even if the chip size is small (1 mm). Therefore, the work division device 10 can solve the problem of not dividing the planned division line that occurs when the chip size is small (1 mm).

The inner edge 16B of the expansion restriction ring 16, which comes into line contact with the adhesive layer of the annular region 3B, is surface-treated to have an arithmetic mean roughness (Ra) of 1.6 (μm), for example. This makes it possible to prevent the inner edge 16B and the annular region 3B from slipping relative to each other due to friction between them. Also, for example, the inner edge 16B is chamfered to C0.2. This makes it possible to prevent the annular region 3B from breaking due to the reaction force when it receives an expansion force from the annular region 3B.

When the division step of S140 is completed, in the expansion restriction ring retraction step of step S150 in FIG. 7, the expansion restriction ring 16 is moved to the retracted position by the expansion restriction ring moving mechanism 22 with the expand ring 14 placed in the expansion position, as shown in FIG. 9 (F).

Next, in the expanded state maintaining process of step S160 in FIG. 7, as shown in FIG. 9 (G), the expansion retaining ring 18 is raised from the standby position toward the mating position by the expansion retaining ring moving mechanism 32, and the mating portion 30 of the expansion retaining ring 18 is mated with the surface 4A of the frame 4 at the mating position to maintain the expanded state of the dicing tape 3. That is, in the embodiment of the work division device 10, after the expansion process is performed, the expansion restricting ring retracting process of S150 is performed, and after the expansion restricting ring retracting process of S150 is performed, the expanded state maintaining process of S160 is performed.

Next, in the expand ring retraction process of step S170 in FIG. 7, the expand ring 14 is moved downward by the expand ring moving mechanism 22 to the retracted position as shown in FIG. 9 (H), and placed in the retracted position. At this time, the expansion of the dicing tape 3 by the expand ring 14 is released, but since the fitting portion 30 of the expansion retaining ring 18 is fitted to the surface 4A of the frame 4, the expanded state is maintained without loosening. This makes it possible to prevent contact between the chips 6 caused by loosening of the expanded dicing tape 3, and therefore prevents deterioration of the quality of the chips 6.

As described above, the workpiece dividing method using the workpiece dividing device 10 of the embodiment can simultaneously solve the problem of non-division of the dividing line that occurs when the chip size is small, and the problem of reduced chip quality caused by contact between the divided chips.

In the embodiment of the workpiece division method, the expansion process from the expansion start process of S120 to the division process of S140 is performed, followed by the expansion restriction ring evacuation process of S150, and then the expansion state holding process of S160, but this process is not limited to this. For example, the expansion process from the expansion start process of S120 to the division process of S140 is performed, followed by the expansion state holding process of S160, followed by the expansion state holding process of S160, followed by the expansion restriction ring evacuation process of S150. In this case, when the expansion holding ring 18 holds the expanded state of the dicing tape 3, the fitting portion 30 collides with the expansion restriction ring 16 in the expansion holding position. For this reason, in the embodiment, the expansion retaining ring 18 cannot perform the expansion restricting ring retraction step S150 after the expansion state retaining step S160. However, for example, by using the tape expansion retaining ring disclosed in JP 2009-253071 A, the expansion restricting ring retraction step S150 can be performed after the expansion state retaining step S160. The tape expansion retaining ring described in JP 2009-253071 A is disposed on the same side of the dicing tape as the wafer attachment surface, and the tape expansion retaining ring is pushed down from the raised position to the lowered position by the lifting mechanism. As a result, the dicing tape in the expanded state is sandwiched between the ring located below the dicing tape and the tape expansion retaining ring, and the expanded state is retained. Then, after the step of retaining this expanded state, the expansion restricting ring retraction step S150 can be performed.

The workpiece division method is not limited to the above example. For example, the expand ring 14 may be moved to the retracted position (S170) and then the expansion retaining ring 18 may be moved to the mating position (S160). In this division method, the dicing tape 3 slackens once immediately after the expand ring 14 is moved to the retracted position, but the dicing tape 3 can be expanded again and maintained in this expanded state by moving the expand retaining ring 18 to the mating position. In this division method, it is preferable to control the movement speed of the expand ring 14 to the retracted position to a slow speed in order to mitigate collisions between the chips 6 caused by the dicing tape 3 suddenly loosening.

Here, we will explain the results of experiments conducted by the inventor to confirm the effectiveness of this invention.

The graph in Figure 10 shows the expansion rate of the annular region (diameter 350 mm) when no expansion restriction ring is used for the wafer unit 2 in Figure 13, and the expansion rate of the inner peripheral region when an expansion restriction ring is used, with the diameter of the expansion restriction opening set to 346 mm, 342 mm, and 338 mm. Note that the "MD (Machine Direction)" in Figure 10 is the direction parallel to the feed direction during the manufacture of the dicing tape 3, and is the direction with the small spring constant. Also, the "CD (Cross Direction)" is the direction perpendicular to the MD, and is the direction with the large spring constant.

According to the experimental results in Figure 10, the expansion rate of the annular region when no expansion restriction ring was used was 6.1% in "MD" and 6.0% in "CD". In contrast, as the diameter of the expansion restriction opening was reduced to 346 mm, 342 mm, and 338 mm, the expansion rate of the inner circumference region increased to 6.8%, 7.5%, and 8.4% in "MD", and to 7.2%, 7.5%, and 8.1% in "CD". In other words, it was confirmed that the chip separation ability improved as the diameter of the expansion restriction opening was reduced.

The graph in FIG. 11 shows the chip division rate (diameter 350 mm) when no expansion restriction ring is used for the wafer unit 2 in FIG. 13, and the chip division rate when an expansion restriction ring is used, with the diameter of the expansion restriction opening set to 338 mm. Note that the division rate "with DAF" in FIG. 11 is the division rate of chips 6 when the wafer 1 is attached to the dicing tape 3 via the DAF, and the division rate "without DAF" is the division rate of chips 6 when the wafer 1 is directly attached to the dicing tape 3.

According to the experimental results in Figure 11, the division rate of the chip 6 when the expansion restriction ring was not used was 15.0% with DAF and 41.0% without DAF. In contrast, when an expansion restriction ring with an expansion restriction opening diameter of 338 mm was used, the division rate of the chip 6 increased to 61.0% with DAF and to 100% without DAF. In other words, it was confirmed that the division ability of the chip 6 is improved by using the expansion restriction ring, whether with DAF or without DAF.

From the above experimental results, it was confirmed that, according to the embodiment of the workpiece dividing device 10, the expansion of the outer peripheral region 3E is restricted by the expansion restricting ring 16, and only the inner peripheral region 3F is expanded, so that the expansion rate is increased compared to the annular region 3B, and the tension applied to the wafer 1 can be increased, thereby solving the problem of non-division of the planned dividing line 5 that occurs when the chip size is small.

1...wafer, 2...wafer unit, 3...dicing tape, 3A...central region, 3B...annular region, 3C...fixed region, 3D...contact portion, 3E...outer peripheral region, 3F...inner peripheral region, 4...frame, 5...planned division line, 6...chip, 7...frame fixing member, 8...expanding ring, 10...work division device, 14...expanding ring, 14A...expansion opening, 16...expanding restricting ring, 16A...expanding restricting opening, 16B...inner edge, 18...expanding retaining ring, 20...expanding ring moving mechanism, 22...expanding restricting ring moving mechanism, 24...pin, 26...hole, 28...main ring, 30...fitting portion, 32...expanding retaining ring moving mechanism, 34...control portion

Claims (4)

A workpiece dividing device in which an outer periphery of a dicing tape is fixed to a ring-shaped frame having an inner diameter larger than an outer diameter of a workpiece, and the workpiece attached to the dicing tape is divided into individual chips along a planned division line,
an expanding ring disposed on the back side of the dicing tape opposite the surface to which the work is attached, the expanding ring being formed in a ring shape having an opening smaller than the inner diameter of the frame and larger than the outer diameter of the work, the expanding ring being moved in a direction approaching the dicing tape relatively to press against the dicing tape to expand it;
an expansion restriction ring arranged on the same side of the dicing tape as the application surface of the workpiece, the expansion restriction ring being formed in a ring shape having an opening smaller than the inner diameter of the frame and larger than the outer diameter of the expansion ring, the expansion restriction ring being brought into contact with the dicing tape when the dicing tape is expanded, and restricting the expansion of an outer circumferential region of the dicing tape located on the outer circumferential side of the contact portion brought into contact with the expansion restriction ring;
an expansion retaining ring that is arranged on a back surface side of the dicing tape opposite to the application surface of the work, is formed in a ring shape larger than an inner diameter of the frame, and retains the expanded state of the dicing tape;
A workpiece dividing device comprising: A frame fixing member for fixing the frame is provided,
The workpiece dividing device according to claim 1 , wherein the expansion restricting ring is detachably fixed to the frame fixing member at a position where the expansion of the outer circumferential side region is restricted. The frame fixing member is configured in a ring shape having an opening larger than an inner diameter of the frame,
The workpiece dividing device according to claim 2 , wherein the expansion restricting ring is attached to an inner circumferential surface of the opening of the frame fixing member. The workpiece dividing device according to claim 2 or 3, wherein the frame fixing member is provided with a fixing member that detachably fixes the expansion restriction ring.

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