Workpiece dividing device

Abstract

To provide a work division device that can simultaneously solve a problem of non-division along a division line that occurs when the chip size is small, and a problem of reduced chip quality caused by contact between chips after division.SOLUTION: In a work division device (10), an expanding ring arranged on the back side of a dicing tape opposite a work attachment surface presses an annular region of the dicing tape that is more inward than the inner edge of a frame, expanding the dicing tape, and an expansion control ring (16) arranged on the same side of the dicing tape as the work attachment surface is abutted at a position in the annular region that is more outer than the pressing position of the expanding ring, thereby restricting the expansion of the outer peripheral region of the annular region that is located on the outer side of the abutment portion abutted by the expansion control ring.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a workpiece dividing device and a workpiece dividing method, and more particularly to a workpiece dividing device and a workpiece dividing method for dividing a workpiece such as a semiconductor wafer into individual chips along planned division lines. [Background technology]

[0002] Conventionally, in the manufacture of semiconductor chips (hereinafter referred to as chips), a workpiece dividing device has been known that divides a semiconductor wafer (hereinafter referred to as wafer) into individual chips along the dividing lines, the semiconductor wafer having dividing lines formed therein in advance by half-cutting with a dicing blade or by forming a modified region by laser irradiation (see Patent Document 1, etc.).

[0003] Figure 12 is an explanatory diagram of a wafer unit 2 to which a disk-shaped wafer 1 to be divided by a work dividing device is attached, Figure 12(A) is an oblique view of the wafer unit 2, and Figure 12(B) is a vertical cross-sectional view of the wafer unit 2.

[0004] 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.

[0005] In the workpiece dividing device, the frame 4 of the wafer unit 2 is fixed by abutting it against a frame fixing member (also called a frame fixing mechanism) 7, indicated by a two-dot chain line. After this, an expansion ring (also called a push-up ring) 8, indicated by a two-dot chain line, is raised from below the wafer unit 2, and this expansion ring 8 presses against the dicing tape 3, expanding it 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 and Y directions, 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 spacing between the lines is equal, the divided chips 6 will 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 spacing between the lines is equal, the divided chips 6 will have a rectangular shape.

[0006] 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 conceivable to cool the dicing tape 3 and expand it in a state where its spring constant is increased.

[0007] The tape expanding 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 below, thereby cooling the dicing tape.

[0008] On the other hand, the chip separation device (workpiece separation device) of Patent Document 3 focuses on the anisotropy of dicing tape and is equipped with a film surface support mechanism to uniformly expand the dicing tape while taking this anisotropy into account. This film surface support mechanism has multiple support mechanisms that are independent in the circumferential direction, and by individually controlling the relative heights of the multiple support mechanisms to adjust the tension of the dicing tape, the elongation of the dicing tape in the X and Y directions is independently controlled.

[0009] In this specification, the area of ​​the dicing tape 3 that is circular in plan view to which the wafer 1 is attached is referred to as the central area 3A, the area that is doughnut-shaped in plan view and that is provided 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 area that is doughnut-shaped in plan view at the outermost periphery that is 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.

[0010] 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 increase as the number of dividing lines 5 increases. Regarding the number of dividing lines 5, for example, if the wafer 1 has a diameter of 300 mm and the chip size is 5 mm, approximately 120 dividing lines 5 (60 in each of the X and Y directions) will be formed, and if the chip size is 1 mm, approximately 600 dividing lines 5 will be formed. Therefore, the tension that must be generated in the annular region 3B must increase as the chip size decreases.

[0011] On the other hand, in the field of workpiece dividing devices, it is also required to prevent deterioration in chip quality due to contact between chips after division by maintaining the expanded state of the dicing tape expanded by the expanding ring.

[0012] Patent Document 4 discloses a workpiece dividing device equipped with a sub-ring that satisfies this requirement. The sub-ring in Patent Document 4 has the function of holding the dicing tape expanded by the expanding 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 dicing tape has finished expanding due to the expanding ring. Maintaining the expanded state of the dicing tape in this manner prevents the dicing tape from loosening, thereby preventing deterioration in chip quality due to contact between chips. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-149581 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-12585 [Patent Document 3] Patent No. 5912274 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-51368 Summary of the Invention [Problem to be solved by the invention]

[0014] The inner diameter (diameter of the inner edge of the frame) of the frame 4 on which a 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 longitudinal cross-sectional view of the wafer unit 2 in FIG. 13, an annular region 3B having a width of 25 mm exists between the outer edge of the wafer 1 and the inner edge of the frame 4. Furthermore, as shown in the longitudinal cross-sectional views of the essential parts of the workpiece dividing device in FIGS. 14(A) and 14(B), the frame fixing member 7 that fixes the frame 4 is positioned outwardly from the annular region 3B in the in-plane direction of the dicing tape 3, as indicated by arrow A, so as not to come into contact with the annular region 3B expanded by the expansion ring 8.

[0015] Therefore, the force that divides the wafer 1 generated by the rising movement of the expansion 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.

[0016] As shown in the operation diagrams of the workpiece dividing device in Figures 15(A) to 15(E), when the expanding ring 8 comes into contact with the annular region 3B of the dicing tape 3 and the expanding ring 8 rises to begin expanding the dicing tape 3 (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 level, 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 15(E)).

[0017] In a conventional workpiece dividing device, a 300 mm diameter wafer 1 with a die size of 5 mm or more could be divided into individual die 6 without any problems by the tension generated in the annular region 3B. However, as the circuit patterns formed on the wafer 1 become finer, smaller die sizes of 1 mm or less have appeared. In this case, the number of dividing lines 5 along which the wafer 1 is divided increases, which increases the force required to divide the wafer 1, and sometimes requires a force greater than the tension generated by the expansion of the annular region 3B. This causes a problem in that, as shown in the longitudinal 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 dividing lines 5 formed on the wafer 1 remain undivided.

[0018] This problem of unseparated planned division lines 5 cannot be resolved by increasing the expansion amount or expansion speed of dicing tape 3. For example, if the expansion amount of dicing tape 3 is increased, the annular region 3B begins to undergo plastic deformation. Because 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 separate 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 dicing tape 3 is increased, a portion of the annular region 3B begins to undergo plastic deformation, so no tension is generated to separate the wafer 1 into individual chips 6. This is because the frequency response of dicing tape 3 is low, and force is not transmitted to the entire dicing tape 3 without a time lag.

[0019] In order to solve the problem of non-division of the 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 sufficiently effective for the small chips of 1 mm or less that are common these days.

[0020] Furthermore, although the chip separation and division device of Patent Document 3 can independently control the elongation of the dicing tape in the X and Y directions, it 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 division lines not being divided.

[0021] Furthermore, the workpiece dividing devices of Patent Documents 1 to 3 do not have a sub-ring like Patent Document 4, which may lead to a problem of reduced chip quality caused by contact between chips after division. As such, no conventional workpiece dividing device can solve the problem of small chips not being divided along the planned dividing line while also solving 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.

[0022] The present invention has been made in consideration of such problems, and aims to provide a work dividing device and a work dividing method that can simultaneously solve the problem of non-division of the planned dividing line that occurs when the chip size is small, and the problem of reduced chip quality due to contact between chips after division. [Means for solving the problem]

[0023] In order to achieve the object of the present invention, the workpiece dividing device of the present invention has an outer periphery of a dicing tape fixed to a ring-shaped frame having an inner diameter larger than the outer diameter of the workpiece, and divides the workpiece attached to the dicing tape into individual chips along a planned division line. The workpiece dividing device comprises: an expanding ring, which is arranged on the back side of the dicing tape opposite the surface on which the workpiece is attached, and has an opening smaller than the inner diameter of the frame and larger than the outer diameter of the workpiece; the expanding ring is moved in a direction approaching the dicing tape relatively to press and expand the dicing tape; and an opening smaller than the inner diameter of the frame and larger than the outer diameter of the expanding ring, which is arranged on the same side of the dicing tape as the surface on which the workpiece is attached, and the expansion restriction ring is formed in a ring shape and has a diameter greater than the inner diameter of the frame, and the expansion restriction ring abuts against the dicing tape when the dicing tape is expanded, restricting the expansion of an outer region of the dicing tape located on the outer side of the abutment portion abutting 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 region; and an expansion retaining ring that is formed in a ring shape and has an elastically deformable fitting portion that is larger than the inner diameter of the frame, and is positioned on the back side of the dicing tape opposite the workpiece attachment surface, and the expansion retaining ring maintains the expanded state of the dicing tape by having the fitting portion fit onto the surface of the frame after the expansion restriction ring is moved away from the position where it restricts the expansion of the outer region by the expansion restriction ring moving mechanism.

[0024] According to the workpiece dividing device of the present invention, with the expansion limiting ring positioned to limit the expansion of the outer peripheral region, the expanding ring is moved relatively closer to the dicing tape. The expanding ring presses the dicing tape to begin expanding the dicing tape, causing the dicing tape to abut against the expansion limiting ring. At this time, the dicing tape is divided into an outer peripheral region located on the outer periphery and an inner peripheral region located on the inner periphery, with the abutment point on the expansion limiting ring as the boundary. Then, during the expanding operation by the expanding ring after the dicing tape abuts against the expansion limiting ring, only the inner peripheral region expands, while the expansion of the outer peripheral region is limited by the expansion limiting ring. In other words, the workpiece is applied with a tension equal to the spring constant of the inner peripheral region, which is greater than the spring constant of the dicing tape. This increases the tension applied to the workpiece, thereby eliminating the problem of unseparated division along the planned division line that occurs when the chip size is small. When the chip division is complete, the expansion-retaining ring moving mechanism retracts the expansion-restricting ring from the position where it restricts the expansion of the outer peripheral region, and then the fitting portion of the expansion-retaining ring fits onto the surface of the frame to maintain the expanded state of the dicing tape. This simultaneously solves the problem of small chips not being divided along the planned division line and the problem of reduced chip quality due to contact between chips after division.

[0025] In one aspect of the present invention, it is preferable that the frame fixing member for fixing the frame is provided, and the expansion restricting ring is detachably fixed to the frame fixing member at a position where it restricts the expansion of the outer peripheral region.

[0026] According to this aspect, 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, thereby reliably restricting the expansion of the dicing tape.

[0027] In one aspect of the present invention, the frame fixing member is preferably configured in a ring shape having an opening larger than the inner diameter of the frame, and the expansion restriction ring is preferably attached to the inner surface of the opening of the frame fixing member.

[0028] According to one aspect of the present invention, the position expansion restriction ring can be attached at an appropriate position for restricting the expansion of the outer peripheral region.

[0029] In one aspect of the present invention, the frame fixing member is preferably provided with a fixing member for detachably fixing the expansion limiting ring.

[0030] According to one aspect of the present invention, the expansion restricting ring can be fixed to the frame fixing member by the fixing member.

[0031] In order to achieve the object of the present invention, the workpiece dividing method of the present invention comprises fixing the outer peripheral portion 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 division line, and moving an expand ring arranged on the back side of the dicing tape opposite to the surface on which the workpiece is attached in a direction approaching the dicing tape relatively, so that the expand ring presses against the annular region of the dicing tape between the outer edge of the workpiece and the inner edge of the frame, thereby dividing the dicing tape an expansion restricting step in which, while the expansion step is being performed, an expansion restricting ring arranged on the same side of the dicing tape as the work attachment surface is abutted against a position in the annular region of the dicing tape that is outer than the pressing position of the expanding ring, thereby restricting expansion of an outer peripheral region located on the outer side of the abutment portion in the annular region that abuts against the expansion restricting ring; an expansion restricting ring retracting step in which the expansion restricting ring is retracted from the position where it restricts expansion of the outer peripheral region; and an expansion state maintaining step in which the expanded state of the dicing tape expanded by the expansion step is maintained by an expansion maintaining ring.

[0032] According to the workpiece dividing method of the present invention, it is possible to simultaneously solve the problem of non-division of the planned dividing line that occurs when the chip size is small, and the problem of reduced chip quality due to contact between chips after division.

[0033] In one aspect of the present invention, it is preferable that the expansion step is performed after the expansion restriction ring retraction step, and that the expansion state maintaining step is performed after the expansion restriction ring retraction step.

[0034] In one aspect of the present invention, an expansion retaining ring is placed on the back side of the dicing tape opposite the workpiece attachment surface, and the expansion state maintaining process preferably involves moving the expansion retaining ring in a direction approaching the dicing tape relatively, thereby engaging an elastically deformable fitting portion formed on the outer periphery of the expansion retaining ring with the surface of the frame to maintain the expanded state of the dicing tape. [Effects of the Invention]

[0035] According to the present invention, it is possible to simultaneously solve the problem of non-division along the planned division lines that occurs when the chip size is small, and the problem of reduced chip quality due to contact between chips after division. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a structural diagram of a main part of a dividing stage of a workpiece dividing device according to an embodiment of the present invention; [Figure 2] An enlarged perspective view of the main part of the split stage shown in Figure 1 [Figure 3] 1 is a cross-sectional view of a wafer unit showing the shape of the annular region during expansion. [Figure 4] A vertical cross-sectional view showing the expansion of the dicing tape by the expansion retaining ring. [Figure 5] Enlarged cross-sectional view of the main part of Figure 4 [Figure 6] Block diagram showing the control system of the workpiece dividing device [Figure 7] 1 is a flowchart showing an example of a wafer dividing method. [Figure 8]Operational diagram of the workpiece dividing device [Figure 9] Operational diagram of the workpiece dividing device [Figure 10] Graph showing the expansion rate of the annular region and the inner peripheral region when the expansion restriction ring is used and when it is not used. [Figure 11] Graph showing chip split rates with and without the extended regulation ring [Figure 12] An explanatory diagram of a wafer unit with a wafer attached [Figure 13] Vertical cross section of wafer unit [Figure 14] Side view of the main part of the workpiece dividing device [Figure 15] Operation diagram of workpiece dividing device [Figure 16] A longitudinal cross-sectional view of a wafer unit into which wafers are separated. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, 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 accompanying 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.

[0038] Fig. 1 is a longitudinal sectional view of a main part of a dividing stage provided in a work dividing device 10 according to an embodiment, and Fig. 2 is an enlarged perspective view of a 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 having a diameter of 300 mm is mounted, as shown in Fig. 13, is exemplified.

[0039] 2, the workpiece dividing device 10 is a device that divides a wafer 1, on which planned dividing lines 5 have been 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 orthogonal to each other. In the embodiment, a wafer 1 in which the number of planned dividing lines 5 parallel to the X direction and the number of planned dividing lines 5 parallel to the Y direction are 300 each, and the distance between the lines is equal, that is, a wafer 1 to be divided into chips 6 with a chip size of 1 mm, is exemplified.

[0040] 1 and 2, the wafer 1 is attached to the center of a dicing tape 3 whose outer periphery is fixed to a 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 donut-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.

[0041] The thickness of the wafer 1 is, for example, about 50 μm. Furthermore, for example, a PVC (polyvinyl chloride) tape is used as the dicing tape 3. 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 adhesive can be used as the film-like adhesive.

[0042] The workpiece dividing device 10 comprises a frame fixing member 7 (see Figures 14 and 15) that fixes the frame 4, an expanding ring 14 that abuts against the annular region 3B of the dicing tape 3 from below and presses against the dicing tape 3 to expand it, an expansion restricting ring 16 that the dicing tape 3 abuts against when the dicing tape 3 is expanded by the expanding ring 14, and an expansion retaining ring 18 that maintains the expanded state of the dicing tape 3 expanded by the expanding ring 14.

[0043] The frame fixing member 7 is disposed on the same side of the dicing tape 3 as the surface to which the wafer 1 is attached, 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 arrow A so as not to come into contact with the annular region 3B expanded by the expanding ring 14.

[0044] 2, the frame fixing member 7 is ring-shaped with an opening 7B having 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-shaped material with an opening 7B, or a frame fixing member made up of multiple fixing members arranged at predetermined intervals 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.

[0045] The expanding ring 14 is disposed on the back surface of the dicing tape 3 opposite the surface to which the wafer 1 is attached, 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 expanding ring 14 is disposed so as to be movable in a direction approaching the dicing tape 3. Specifically, the expanding ring 14 is disposed so as to be movable in the vertical direction between an expanding position (position indicated by a two-dot chain line in FIG. 1) where it presses against the back surface of the annular region 3B of the dicing tape 3 to expand the annular region 3B, and a retracted position (position indicated by a solid line in FIG. 1) where it is retracted downward from the expanding position.

[0046] 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 an expanded position and a 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 also be used instead. When the expand ring 14, which is positioned 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, causing it to expand radially. Alternatively, the expand ring 14 may be fixed and the wafer unit 2 moved downward in the direction of arrow C to press the annular region 3B with the expand ring 14. When the annular region 3B is expanded by the expand ring 14, it abuts against the expansion limiting ring 16.

[0047] The expansion control ring 16 is positioned on the same side of the dicing tape 3 as the wafer 1 attachment surface, and is formed in a ring shape with an expansion control 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.

[0048] 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 retracted position (a position shown by a two-dot chain line in FIG. 1) where the ring is retracted upward from the expansion restriction position. The outer peripheral region 3E will be described later.

[0049] 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.

[0050] Furthermore, it is preferable that the expansion limiting ring 16 be detachably attached to the inner circumferential surface of the opening 7B of the frame fixing member 7 at the expansion limiting position. This allows the expansion limiting ring 16 to be attached at an appropriate position that restricts the expansion of the outer peripheral region 3E. Furthermore, the expansion limiting ring 16 is fixed to the frame fixing member 7 at the expansion limiting position by a fixing member. The fixing member is not particularly limited, but an example is a fixing member using multiple pins 24. In this fixing member, the pins 24 are arranged on the inner circumferential surface of the opening 7B so that they can be protruded and retracted, and holes 26 into which the protruding pins 24 fit are formed on the outer circumferential surface of the expansion limiting ring 16. That is, with this fixing member, when the expansion limiting ring 16 is attached to the inner circumferential surface of the opening 7B, the pins 24 protrude from the frame fixing member 7 and fit into the holes 26 of the expansion limiting ring 16. This allows the expansion limiting ring 16 to be fixed to the inner circumferential surface of the opening 7B of the frame fixing member 7. The fixing position of the expansion restricting ring 16 relative to the frame fixing member 7 is not limited to the inner surface of the opening 7B, but may be any position that can properly restrict the expansion of the outer peripheral region 3E, for example, the surface of the frame fixing member 7 may be the fixing position.

[0051] Here, the frame fixing member 7 is fixed to a fixed structure of the workpiece dividing 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. Therefore, the expansion restriction ring 16 receives a force from the annular region 3B. If the expansion restriction ring 16 is displaced upward by the force from the annular region 3B, the expansion of the outer peripheral region 3E cannot be properly restricted. However, in this embodiment, the expansion restriction ring 16 is securely fixed to the frame fixing member 7 via the pin 24 at the expansion restriction position, preventing displacement due to the force from the annular region 3B, and properly restricting the expansion of the outer peripheral region 3E. It should be noted that the expansion restriction ring 16 may be fixed at 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.

[0052] FIG. 3 is a vertical cross-sectional view of the wafer unit 2 showing the shape of the annular region 3B in the middle of being expanded by the expand ring 14. As shown in FIG.

[0053] 3, when the annular region 3B is expanded by the expanding ring 14, the annular region 3B abuts against the expansion limiting ring 16. Specifically, the annular region 3B abuts against an inner edge portion 16B on the back side of the expansion limiting ring 16. In other words, the expansion limiting ring 16 abuts against a position on the annular region 3B that is outer than the pressing position of the expanding ring 14.

[0054] 1, the diameter of the expansion-restricting opening 16A is set to 338 mm. As a result, the width of the outer peripheral region 3E, whose expansion is restricted by the expansion-restricting ring 16, is set to 6 mm, and the width of the inner peripheral region 3F of the annular region 3B excluding the outer peripheral region 3E is set to 19 mm.

[0055] Here, the inner peripheral region 3F of the annular region 3B, whose expansion is not restricted by the expansion restricting ring 16, is the region that substantially contributes to dividing the wafer 1. That is, as the width dimension of the inner peripheral region 3F is reduced, the spring constant of the inner peripheral region 3F increases, and therefore it is possible to increase the tension applied from the inner peripheral region 3F to the wafer 1. Therefore, it is preferable to set the width dimension of the inner peripheral region 3F in accordance with the division conditions defined by the number of planned division lines 5, etc.

[0056] The expansion retaining ring 18, which maintains the expanded state of the dicing tape 3, is disposed on the back surface 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 attached to the outer periphery of the main ring 28 and whose outer diameter (351.3 mm) is larger than the inner diameter (350 mm) of the frame 4.

[0057] 4 is a vertical cross-sectional view of the dicing tape 3 in an expanded state maintained by the expansion maintaining ring 18. FIG. 5 is an enlarged cross-sectional view of a main part of FIG.

[0058] 4 and 5, the fitting portion 30 of the expansion retaining ring 18 fits onto the surface 4A of the frame 4 at the fitting position shown by the solid line via the annular region 3B of the dicing tape 3. This causes the expanded state of the dicing tape 3 to be maintained by the expansion retaining ring 18.

[0059] Before expansion and retention, the expansion retaining ring 18 waits in a standby position (the position shown by the solid line in FIG. 1) below the mating position indicated by the solid lines in FIGS. 4 and 5. During expansion and retention, the expansion retaining ring moving mechanism 32 moves it up from the standby position to the mating position. A feed screw device is shown as an example of the expansion retaining ring moving mechanism 32, but an actuator such as an air cylinder device can also be used instead. When the expansion retaining ring 18 is raised by the expansion retaining ring moving mechanism 32, the mating portion 30 abuts against the underside of the frame 4. The mating portion 30 is then pushed against the inner circumferential surface of the frame 4, elastically deforming and rising. The rise of the expansion retaining ring 18 is stopped when the mating portion 30 passes the inner circumferential surface of the frame 4. As a result, the mating portion 30 is mated with the surface 4A of the frame 4 at the mating position, as shown in FIGS. 4 and 5. Alternatively, the expansion retaining ring 18 may be fixed and the dicing tape 3 may be moved in a direction closer to the expansion retaining ring 18. That is, the expansion holding ring 18 is moved in a direction relatively approaching the dicing tape 3 so that the fitting portion 30 fits onto the surface 4A of the frame 4.

[0060] The operation of the expansion ring moving mechanism 20 that drives the expansion ring 14, the expansion restriction ring moving mechanism 22 that drives the expansion restriction 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 dividing device 10, as shown in the block diagram of the control system in Figure 6.

[0061] An example of a workpiece dividing method performed by the control unit 34 will be described below.

[0062] First, the control unit 34 controls the expansion restriction ring moving mechanism 22 to position the expansion restriction ring 16 at the expansion restriction position, and then controls the expand ring moving mechanism 20 to move the expand ring 14 to the expanded 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 fitting position. Next, the control unit 34 controls the expand ring moving mechanism 20 to move the expand ring 14 to the retracted position.

[0063] Next, the above-mentioned work dividing method will be specifically described with reference to the flowchart of FIG. 7 and the operation explanatory diagrams of the work dividing device 10 shown in FIGS. 8(A) to 8(D) and FIGS. 9(E) to 9(H).

[0064] 7, the expanding ring 14 is placed in the retracted position by the expanding ring moving mechanism 20, the expansion limiting ring 16 is placed in the expanded limiting position by the expansion limiting ring moving mechanism 22, and the expansion retaining ring 18 is placed in the standby position by the expansion retaining ring moving mechanism 32, as shown in FIG. 8(A). At this time, the expansion limiting ring 16 is fixed to the frame fixing member 7 via the pin 24.

[0065] 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).

[0066] 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, thereby starting expansion of the entire 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 contact with it, or an air-cooling type that cools the annular region 3B by spraying cold air onto it.

[0067] Next, in the expansion restriction process of step S130 in FIG. 7, when the upward movement of the expanding ring 14 exceeds the thickness of the frame 4, the annular region 3B abuts against the expansion restriction ring 16, as shown in FIG. 8(D). 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. 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 performed during the expansion process from the expansion start process of S120 to the division process of S140. In other words, the expansion process is a fixed process that includes the expansion start process of S120, the expansion restriction process of S130, and the division process of S140.

[0068] Next, in the dividing process of step S140 in Fig. 7, as shown in Fig. 9(E), the expanding ring 14 continues to move upward, and the inner peripheral region 3F of the annular region 3B, excluding the outer peripheral region 3E in Fig. 3, is continuously expanded, thereby dividing the wafer 1 into individual chips 6. After this, when the expanding ring 14 reaches the expanded position, the upward movement of the expanding ring 14 is stopped. In other words, the expansion and fixation is completed at this point.

[0069] In the dividing step of S140, in the expansion operation by the expand ring 14 after the annular region 3B abuts against the inner edge portion 16B of the expansion restriction ring 16, only the inner region 3F expands while the expansion of the outer region 3E is restricted by the expansion restriction ring 16. In other words, 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.

[0070] Specifically, the length of the annular region 3B, which contributes to dividing the wafer 1, is shortened from 25 mm (the width of the annular region 3B) to 19 mm (the width of the inner peripheral region 3F), and the spring constant increases in inverse proportion to this. As a result, even if only the inner peripheral region 3F is expanded, the spring constant of the inner peripheral 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 workpiece dividing device 10 can solve the problem of not dividing the wafer 1 along the intended dividing line, which occurs when the chip size is small (1 mm).

[0071] 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 prevents the inner edge 16B and the annular region 3B from slipping relative to each other due to friction between them. The inner edge 16B is also chamfered to a C0.2 chamfer, for example. This prevents the annular region 3B from breaking due to the reaction force when an expansion force is applied from the annular region 3B.

[0072] After the division process of S140 is completed, in the expansion restriction ring retraction process of step S150 in Figure 7, the expansion restriction ring 16 is moved to the retracted position by the expansion restriction ring moving mechanism 22 while the expand ring 14 is placed in the expanded position, as shown in Figure 9 (F).

[0073] 7, in the expanded state maintaining process, step S160, as shown in FIG. 9(G), the expansion retaining ring 18 is raised from the standby position toward the fitting position by the expansion retaining ring moving mechanism 32, and the fitting portion 30 of the expansion retaining ring 18 is fitted to the surface 4A of the frame 4 at the fitting position to maintain the expanded state of the dicing tape 3. That is, in the work dividing device 10 of the embodiment, 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.

[0074] Next, in the expanding ring retraction process of step S170 in Figure 7, the expanding ring 14 is moved downward by the expanding ring moving mechanism 22 to the retracted position, as shown in Figure 9(H), and placed at the retracted position. At this time, the dicing tape 3 is released from expansion by the expanding ring 14, but the fitting portion 30 of the expansion retaining ring 18 is fitted into the surface 4A of the frame 4, so the expanded state is maintained without loosening. This prevents contact between chips 6 that would occur when the expanded dicing tape 3 loosens, and therefore prevents deterioration in the quality of the chips 6.

[0075] According to the work dividing method using the work dividing device 10 of the embodiment described above, it is possible to simultaneously solve the problem of non-division of the planned dividing line that occurs when the chip size is small, and the problem of reduced chip quality due to contact between chips after division.

[0076] In the workpiece dividing method according to the embodiment, the expansion process from the expansion start process of S120 to the dividing process of S140 is performed, followed by the expansion limiting ring retraction process of S150, and then the expansion limiting ring retraction process of S150, followed by the expansion state maintaining process of S160. However, this process is not limited to this. For example, the expansion process from the expansion start process of S120 to the dividing process of S140 may be performed, followed by the expansion state maintaining process of S160, followed by the expansion limiting ring retraction process of S150. In this case, when the expansion maintaining ring 18 maintains the expanded state of the dicing tape 3, the fitting portion 30 collides with the expansion limiting ring 16, which is in the expansion limiting position. For this reason, with the expansion retaining ring 18 of the embodiment, the expansion-restriction ring retraction step S150 cannot be performed after the expansion-state maintaining step S160. However, for example, by using a tape expansion retaining ring disclosed in Japanese Patent Application Laid-Open No. 2009-253071, the expansion-restriction ring retraction step S150 can be performed after the expansion-state maintaining step S160. The tape expansion retaining ring described in Japanese Patent Application Laid-Open No. 2009-253071 is positioned on the same side of the dicing tape as the wafer attachment surface, and the tape expansion retaining ring is pushed down from its raised position to its lowered position by an elevator mechanism. As a result, the expanded dicing tape is sandwiched between the ring positioned below the dicing tape and the tape expansion retaining ring, maintaining the expanded state. Then, after the step of maintaining this expanded state, the expansion-restriction ring retraction step S150 can be performed.

[0077] Furthermore, the workpiece division method is not limited to the above example. For example, after moving the expanding ring 14 to the retracted position (S170), the expansion retaining ring 18 may be moved to the fitting position (S160). In this division method, the dicing tape 3 temporarily loosens immediately after moving the expanding ring 14 to the retracted position. However, by moving the expansion retaining ring 18 to the fitting position, the dicing tape 3 can be expanded again and maintained in this expanded state. In this division method, it is preferable to control the speed at which the expanding ring 14 is moved to the retracted position to a low speed in order to mitigate collisions between the chips 6 caused by the dicing tape 3 suddenly loosening.

[0078] Here, the results of an experiment conducted by the inventor to confirm the effects of the present invention will be described.

[0079] 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 the 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 manufacturing of the dicing tape 3 and is the direction with a small spring constant. Also, the "CD (Cross Direction)" is the direction perpendicular to the MD and is the direction with a large spring constant.

[0080] According to the experimental results shown in Figure 10, when no expansion restriction ring was used, the expansion rate of the annular region was 6.1% in the MD and 6.0% in the 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 peripheral region increased to 6.8%, 7.5%, and 8.4% in the MD, and to 7.2%, 7.5%, and 8.1% in the CD. In other words, it was confirmed that the chip separation ability improved as the diameter of the expansion restriction opening was reduced.

[0081] The graph in Fig. 11 shows the division rate of chips when an expansion restriction ring is not used (diameter 350 mm) for the wafer unit 2 in Fig. 13, and the division rate of chips 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 attached directly to the dicing tape 3.

[0082] According to the experimental results in Figure 11, the division rate of the chip 6 when no expansion restriction ring was 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 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."

[0083] From the above experimental results, it was confirmed that, according to the embodiment of the work division device 10, by restricting the expansion of the outer peripheral region 3E by the expansion restriction ring 16 and expanding only the inner peripheral region 3F, 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 division line 5 that occurs when the chip size is small. [Explanation of symbols]

[0084] 1...wafer, 2...wafer unit, 3...dicing tape, 3A...central region, 3B...annular region, 3C...fixing region, 3D...contact portion, 3E...outer circumferential region, 3F...inner circumferential region, 4...frame, 5...planned division line, 6...chip, 7...frame fixing member, 8...expansion ring, 10...workpiece dividing device, 14...expansion ring, 14A...expansion opening, 16...expansion limiting ring, 16A...expansion limiting opening, 16B...inner edge, 18...expansion retaining ring, 20...expansion ring moving mechanism, 22...expansion limiting ring moving mechanism, 24...pin, 26...hole portion, 28...main body ring, 30...fitting portion, 32...expansion retaining ring moving mechanism, 34...control portion

Claims

1. A workpiece dividing device in which an outer peripheral portion of a dicing tape is fixed to a ring-shaped frame having an inner diameter larger than the outer diameter of a workpiece, and the workpiece attached to the dicing tape is divided into individual chips along planned division lines, an expanding ring that is arranged on a back surface of the dicing tape opposite to the work-attaching surface, is formed in a ring shape with an opening that is smaller than the inner diameter of the frame, and presses the dicing tape to expand it; an expansion restriction ring arranged on the same side of the dicing tape as the work attachment surface, the expansion restriction ring having an opening smaller than the inner diameter of the frame and larger than the outer diameter of the expanding ring, the expansion restriction ring being brought into contact with the dicing tape when the dicing tape is expanded, and restricting expansion of an outer peripheral region of the dicing tape located on the outer peripheral side of the contact portion that contacts the expansion restriction ring; an expansion retaining ring arranged on the back surface of the dicing tape opposite the work-attaching surface, the expansion retaining ring having a ring-like shape and a fitting portion larger than the inner diameter of the frame, the fitting portion fitting into the surface of the frame to maintain the expanded state of the dicing tape; A workpiece dividing device comprising:

2. a frame fixing member for fixing the frame; 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 restricting ring restricts the expansion of the outer peripheral side region.

3. 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.

4. 4. The workpiece dividing device according to claim 2, wherein the frame fixing member is provided with a fixing member for detachably fixing the expansion restricting ring.

Images