Work division method

Abstract

This invention provides a workpiece division method that can simultaneously resolve the problem of undivided division lines that occur when using small chips, and the problem of chip quality degradation caused by contact between divided chips. [Solution] The workpiece division method involves using an expand ring (14) positioned on the back side of the dicing tape opposite to the surface to which the workpiece is attached to press against the annular region of the dicing tape that is inside the inner edge of the frame, thereby expanding the dicing tape. An expansion restricting ring (16) positioned on the same side of the dicing tape as the surface to which the workpiece is attached is brought into contact with the annular region of the dicing tape at a position outside the pressing position of the expand ring, thereby restricting the expansion of the outer peripheral region located on the outer peripheral side of the contact point with the expansion restricting ring, and the expanded state of the dicing tape is held by an expansion holding ring (18).

Description

Technical Field

[0001] The present invention relates to a workpiece dividing device and a workpiece dividing method, and particularly relates 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 dividing line.

Background Art

[0002] Conventionally, in the manufacture of semiconductor chips (hereinafter referred to as chips), a semiconductor wafer (hereinafter referred to as a wafer) in which a planned dividing line is previously formed inside by a half cut using a dicing blade or formation of a modified region by laser irradiation is divided into individual chips along the planned dividing line. A workpiece dividing device is known (see Patent Document 1, etc.).

[0003] FIG. 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. FIG. 12(A) is a perspective view of the wafer unit 2, and FIG. 12(B) is a longitudinal sectional view of the wafer unit 2.

[0004] The wafer 1 is attached to the central portion of a dicing tape (also referred to as an expansion tape or an adhesive sheet) 3 having a thickness of about 100 μm with an adhesive layer formed on one side, and the outer peripheral portion of the dicing tape 3 is fixed to a rigid ring-shaped frame 4.

[0005] In the workpiece splitting apparatus, the frame 4 of the wafer unit 2 is fixed by contacting the frame fixing member (also called the frame fixing mechanism) 7, which is indicated by a dashed line. After this, an expanding ring (also called a push-up ring), which is indicated by a dashed line, moves upward from below the wafer unit 2, and the dicing tape 3 is pressed and expanded radially by this expanding ring 8. The tension generated in the dicing tape 3 at this time is applied to the division lines 5 of the wafer 1, thereby dividing the wafer 1 into individual chips 6. The division lines 5 are formed in the X and Y directions, which are orthogonal to each other. With respect to the division lines 5, if the number of lines parallel to the X direction and the number of lines parallel to the Y direction are the same, and the spacing between them in each direction is equal, the shape of the divided chips 6 will be square. Also, if 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 them in each direction is equal, the shape of the divided chips 6 will be rectangular.

[0006] Incidentally, 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 while increasing its spring constant.

[0007] The tape expansion device (workpiece splitting device) described in Patent Document 2 is equipped with a cold air supply means. According to Patent Document 2, the dicing tape is cooled by operating the cold air supply means to supply cold air into the processing space and cooling the processing space to, for example, 0°C or below.

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

[0009] In this specification, the circular region of the dicing tape 3 to which the wafer 1 is attached is referred to as the central region 3A, the donut-shaped region 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 is referred to as the annular region 3B, and the outermost donut-shaped region in plan view that is fixed to the frame 4 is referred to as the fixed region 3C. The annular region 3B is the region that is pressed and expanded by the expanding ring 8.

[0010] It is known that the force required to divide wafer 1, that is, the tension that must be generated in the annular region 3B to divide wafer 1, must increase as the number of division lines 5 increases. Regarding the number of division lines 5, for example, if wafer 1 has a diameter of 300 mm and a chip size of 5 mm, approximately 120 division lines 5 (60 in each of the X and Y directions) will be formed, and if the chip size is 1 mm, approximately 600 division 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 splitting equipment, it is also required to maintain the expanded state of the dicing tape expanded by the expander ring, thereby preventing a deterioration in chip quality caused by contact between chips after splitting.

[0012] As a workpiece splitting device that satisfies this requirement, a workpiece splitting device equipped with a sub-ring is disclosed in Patent Document 4. The sub-ring in Patent Document 4 has the function of holding the dicing tape, which has been expanded by the expander ring, in an expanded state, and is configured to have a larger diameter than the inner diameter of the frame. The sub-ring is inserted between the outer circumference of the dicing tape and the surface of the frame immediately after it rises from the back side of the dicing tape toward the dicing tape and passes through the frame. As a result, the expanded state of the dicing tape is maintained even after the expansion of the dicing tape by the expander ring is completed. By maintaining the expanded state of the dicing tape in this way, slack in the dicing tape can be prevented, and thus the deterioration of chip quality caused by contact between chips can be prevented. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Publication No. 2016-149581 [Patent Document 2] Japanese Patent Publication No. 2016-12585 [Patent Document 3] Patent No. 5912274 [Patent Document 4] Japanese Patent Publication No. 2013-51368 [Overview of the Initiative] [Problems that the invention aims to solve]

[0014] Incidentally, the inner diameter (the diameter of the inner edge of the frame) of the frame 4 on which the 300mm diameter wafer 1 is mounted is defined as 350mm according to the SEMI standard (G74-0699 Specification for Tape Frames for 300mm Wafers). According to this standard, as shown in the longitudinal section of the wafer unit 2 in Figure 13, there is an annular region 3B with a width of 25mm between the outer edge of the wafer 1 and the inner edge of the frame 4. Furthermore, as shown in the longitudinal section of the main part of the workpiece splitting device in Figures 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 arrow A, so as not to come into contact with the annular region 3B which is expanded by the expanding ring 8.

[0015] Therefore, the force that divides the wafer 1 generated by the upward movement of the expanding 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 splitting device in Figures 15(A) to (E), the expand ring 8 comes into contact with the annular region 3B of the dicing tape 3, and when the dicing tape 3 begins to expand due to the upward movement of the expand ring 8 (Figure 15(A)), the annular region 3B with 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 splitting of the wafer 1 into chips 6 begins (Figure 15(C)). Once the wafer 1 is split 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)).

[0017] In conventional workpiece splitting devices, when the chip size of a 300 mm diameter wafer 1 was 5 mm or larger, the tension generated in the annular region 3B allowed for the individual chips 6 to be split without any problems. However, with the miniaturization of circuit patterns formed on wafer 1, chips smaller than 1 mm have appeared. In this case, the number of planned splitting lines 5 for splitting wafer 1 increases, resulting in a greater force required to split wafer 1, sometimes exceeding the tension generated by the expansion of the annular region 3B. Consequently, as shown in the longitudinal cross-sectional view of wafer unit 2 in Figure 16, even after the expansion operation by the expander ring 8 is completed, a problem arises where some of the planned splitting lines 5 formed on wafer 1 remain undivided.

[0018] This problem of undivided planned division lines 5 cannot be resolved by increasing the expansion amount or expansion speed of the dicing tape 3. For example, if the expansion amount of the dicing tape 3 is increased, the annular region 3B will begin 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, the tension required to divide the wafer 1 into individual chips 6 does not occur in the region of the annular region 3B beyond the elastic deformation. On the other hand, even if the expansion speed of the dicing tape 3 is increased, a portion of the annular region 3B will begin to undergo plastic deformation, so the tension required to divide the wafer 1 into individual chips 6 does not occur. This is because the frequency response of the dicing tape 3 is low, so force is not transmitted to the entire dicing tape 3 without time lag.

[0019] To resolve the problem of undivided lines 5, Patent Document 2 addresses this by cooling the dicing tape and increasing its spring constant, but this is not sufficiently effective for small chips of 1 mm or less in recent years.

[0020] In addition, although the chip separation device of Patent Document 3 can independently control the elongation in the X direction and the elongation in the Y direction of the dicing tape, it cannot apply a force greater than the tension caused by the expansion of the annular portion region to the wafer, so the problem of non-separation of the planned division line cannot be solved.

[0021] Moreover, since the workpiece dividing devices of Patent Documents 1 to 3 do not have a sub-ring as in Patent Document 4, there is a risk of causing a problem of deterioration in the quality of the chips due to contact between the chips after division. As described above, there is no conventional workpiece dividing device that can solve the problem of non-separation of the planned division line that occurs when the chip size is a small chip and at the same time solve the problem of deterioration in the quality of the chips due to contact between the chips after division, and it has been desired to realize such a device.

[0022] The present invention has been made in view of such problems, and an object thereof is to provide a workpiece dividing device and a workpiece dividing method capable of simultaneously solving the problem of non-separation of the planned division line that occurs when the chip size is a small chip and the problem of deterioration in the quality of the chips due to contact between the chips after division.

Means for Solving the Problems

[0023] The workpiece splitting device of the present invention, in order to achieve the object of the present invention, has a ring-shaped frame having an inner diameter larger than the outer diameter of the workpiece, to which the outer periphery of the dicing tape is fixed, and the workpiece attached to the dicing tape is split into individual chips along a planned splitting line, comprising: an expandable ring formed in the shape of a ring, disposed on the back side of the dicing tape opposite to the 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 expandable ring which expands by pressing the dicing tape when moved in a direction relatively closer to the dicing tape, and an opening on the same side of the dicing tape as the surface on which the workpiece is attached, which is smaller than the inner diameter of the frame and larger than the outer diameter of the expandable ring An expansion restricting ring formed in a ring shape having a contact portion with the dicing tape when the dicing tape is expanded, which restricts the expansion of the outer peripheral region located on the outer peripheral side of the contact portion of the dicing tape that contacts the expansion restricting ring; an expansion restricting ring moving mechanism that moves the expansion restricting ring away from the position that restricts the expansion of the outer peripheral region; and an expansion holding ring formed in a ring shape having an elastically deformable fitting portion larger than the inner diameter of the frame, which is positioned on the back side of the dicing tape opposite to the surface to which the workpiece is attached, and which holds the expanded state of the dicing tape by having its fitting portion fit into the surface of the frame after the expansion restricting ring has been moved away from the position that restricts the expansion of the outer peripheral region by the expansion restricting ring moving mechanism.

[0024] According to the workpiece dividing device of the present invention, with the expansion restricting ring positioned at a position restricting the expansion of the outer peripheral side region, the expandable ring is moved in a direction approaching the dicing tape, and when the dicing tape is pressed by the expandable ring to start expanding the dicing tape, the dicing tape abuts against the expansion restricting ring during the expansion of the dicing tape. At this time, the dicing tape is divided into an outer peripheral side region located on the outer peripheral side and an inner peripheral side region located on the inner peripheral side with the contact portion abutting against the expansion restricting ring as a boundary. Then, in the expansion operation by the expandable ring after the dicing tape abuts against the expansion restricting ring, only the inner peripheral side region expands while the expansion of the outer peripheral side region is restricted by the expansion restricting ring. That is, the tension of the spring constant of the inner peripheral side region, which is larger than the spring constant of the dicing tape, is applied to the workpiece. Thereby, since the tension applied to the workpiece increases, it is possible to solve the problem of the undivided division planned line that occurs when the chip size is a small chip. And when the division of the chip is completed, the expansion restricting ring is retracted from the position restricting the expansion of the outer peripheral side region by the expansion holding ring moving mechanism, and then the fitting portion of the expansion holding ring is fitted to the surface of the frame to hold the expanded state of the dicing tape. Thereby, according to the present invention, it is possible to simultaneously solve the problem of the undivided division planned line that occurs when the chip size is a small chip and the problem of the quality degradation of the chip caused by the contact between the chips after division.

[0025] One aspect of the present invention has a frame fixing member for fixing the frame, and it is preferable that the expansion restricting ring is detachably fixed to the frame fixing member at a position restricting the expansion of the outer peripheral side region.

[0026] According to this aspect, by fixing the expansion restricting ring to the frame fixing member, the expansion restricting ring can be surely fixed at a position restricting the expansion of the outer peripheral side region, so that the expansion of the dicing tape can be surely restricted.

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

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

[0029] In one aspect of the present invention, it is preferable that the frame fixing member is provided with a fixing member for detachably fixing the expansion regulating ring.

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

[0031] The present invention provides a workpiece division method in which, in order to achieve the objectives of the present invention, 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. In this workpiece division method, an expand ring, which is positioned on the back side of the dicing tape opposite to the surface on which the workpiece is attached, is moved in a direction that moves it relatively closer to the dicing tape, thereby pressing the annular region of the dicing tape between the outer edge of the workpiece and the inner edge of the frame with the expand ring, and the dicing tape The system comprises: an expansion step for expanding the dicing tape; an expansion restriction step for restricting the expansion of the outer peripheral region located on the outer side of the contact point with the expansion restriction ring, while the expansion step is being performed, by bringing an expansion restriction ring, positioned on the same side as the workpiece attachment surface of the dicing tape, into contact with a position in the annular region of the dicing tape that is outside the pressing position of the expand ring; an expansion restriction ring retraction step for retracting the expansion restriction ring from the position that restricts the expansion of the outer peripheral region; and an expansion state holding step for holding the expanded state of the dicing tape expanded by the expansion step with an expansion holding ring.

[0032] According to the workpiece division method of the present invention, it is possible to simultaneously resolve the problem of undivided lines on the division schedule that occur when the chip size is small, and the problem of chip quality degradation caused by contact between divided chips.

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

[0034] In one aspect of the present invention, an expansion retaining ring is arranged on the back side of the dicing tape opposite to the surface to which the workpiece is attached, and the expansion state retention step preferably involves moving the expansion retaining ring in a direction that approaches the dicing tape relative to it, thereby engaging the elastically deformable fitting portion formed on the outer circumference of the expansion retaining ring with the surface of the frame to retain the expanded state of the dicing tape. [Effects of the Invention]

[0035] According to the present invention, it is possible to simultaneously resolve the problem of undivided lines on the planned division lines that occur when the chip size is small, and the problem of chip quality degradation caused by contact between divided chips. [Brief explanation of the drawing]

[0036] [Figure 1] Structural diagram of the main part of the splitting stage of the workpiece splitting device of the embodiment [Figure 2] Enlarged perspective view of the main part of the dividing stage shown in Figure 1. [Figure 3] Cross-sectional view of a wafer unit showing the shape of the annular region during expansion. [Figure 4] A longitudinal cross-sectional view showing the expanded state of the dicing tape by the expansion retaining ring. [Figure 5] Figure 4: Enlarged cross-sectional view of the main part [Figure 6] Block diagram showing the control system of a workpiece splitting device. [Figure 7] A flowchart showing an example of a wafer splitting method. [Figure 8]Operational diagram of the workpiece splitting device [Figure 9] Operational diagram of the workpiece splitting device [Figure 10] Graph showing the expansion rates of the annular and inner circumference regions with and without the expansion restriction ring. [Figure 11] A graph showing the chip division ratio with and without the extended regulatory ring. [Figure 12] Diagram illustrating a wafer unit with a wafer attached. [Figure 13] Longitudinal cross-section of a wafer unit [Figure 14] Side view of the main components of the workpiece splitting device. [Figure 15] Operation diagram of the workpiece splitting device [Figure 16] Longitudinal cross-sectional view of a wafer unit after the wafer has been divided. [Modes for carrying out the invention]

[0037] Preferred embodiments of the workpiece splitting apparatus and workpiece splitting method according to the present invention will be described in detail below 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.

[0038] Figure 1 is a longitudinal cross-sectional view of the main part of the splitting stage provided in the workpiece splitting apparatus 10 according to the embodiment, and Figure 2 is an enlarged perspective view of the main part of the splitting stage. Although the size of the wafer unit to be split by the workpiece splitting apparatus 10 is not limited, in this embodiment, a wafer unit 2 on which a wafer 1 with a diameter of 300 mm shown in Figure 13 is mounted is used as an example.

[0039] As shown in Figure 2, the workpiece splitting apparatus 10 is a device that splits a wafer 1 on which splitting lines 5 are formed into individual chips 6 along the splitting lines 5. Multiple splitting lines 5 are formed in mutually orthogonal X and Y directions. In this embodiment, an example is given of a wafer 1 in which the number of splitting lines 5 parallel to the X direction and the number of splitting lines 5 parallel to the Y direction are both 300 and the spacing between them is equal, i.e., a wafer 1 that is split into chips 6 with a chip size of 1 mm.

[0040] As shown in Figures 1 and 2, 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 circular central region 3A in plan view to which wafer 1 is attached, and a donut-shaped annular region 3B in plan view between the outer edge of the central region 3A (the outer edge of wafer 1) and the inner edge of the frame 4.

[0041] The thickness of wafer 1 is, for example, about 50 μm. The dicing tape 3 is, for example, a PVC (polyvinyl chloride) tape. Alternatively, wafer 1 may be attached to the dicing tape 3 via a film-type adhesive such as DAF (Die Attach Film). For example, a PO (polyolefin)-based film-type adhesive can be used.

[0042] The workpiece splitting device 10 includes a frame fixing member 7 (see Figures 14 and 15) for fixing the frame 4, an expand ring 14 that contacts the annular portion region 3B of the dicing tape 3 from below to press and expand the dicing tape 3, an expansion restricting ring 16 that the dicing tape 3 contacts when the dicing tape 3 is expanded by the expand ring 14, and an expansion holding ring 18 that maintains the expanded state of the dicing tape 3 expanded by the expand ring 14.

[0043] The frame fixing member 7 is positioned on the same side as the wafer 1 attachment surface of the dicing tape 3, and the frame 4 is fixed to its lower surface 7A. Furthermore, the frame fixing member 7 is positioned outward 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 expanding ring 14.

[0044] As shown in Figure 2, the shape of the frame fixing member 7 is ring-shaped with an opening 7B that is larger than the inner diameter of the frame 4 (350 mm), for example, a diameter of 361 mm, but its shape is not particularly limited. As the frame fixing member 7, for example, a rectangular plate-shaped material with an opening 7B can be exemplified, or a frame fixing member consisting of a plurality of fixing members arranged at predetermined intervals along the outer circumference of the frame 4 can be exemplified. The inscribed circles of these fixing members are set to be equal to the diameter of the opening 7B.

[0045] The expanding ring 14 is positioned on the back side of the dicing tape 3 opposite to the surface to which the wafer 1 is attached, and is formed in a ring shape having an expansion opening (opening) 14A that is smaller than the inner diameter of the frame 4 (350 mm) and larger than the outer diameter of the wafer 1 (300 mm). The expanding ring 14 is positioned to be movable in a direction that moves relatively closer to the dicing tape 3. Specifically, the expanding ring 14 is positioned to be movable vertically between an expansion position (shown by the dashed line in Figure 1) in which it presses the back side of the annular region 3B of the dicing tape 3 to expand the annular region 3B, and a retracted position (shown by the solid line in Figure 1) which is retracted downward from the expansion position.

[0046] Furthermore, the workpiece splitting device 10 is equipped with an expander ring moving mechanism 20 that moves the expander ring 14 up and down between an expanded position and a retracted position. As an example of the expander ring moving mechanism 20, a lead screw device is shown, but an actuator such as an air cylinder device can also be used instead. When the expander ring 14, which is in the retracted position, is moved toward the expanded position by the expander ring moving mechanism 20, the expander ring 14 moves 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 by the expander ring 14 and expands radially. Alternatively, the expander 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 expander ring 14. The annular region 3B comes into contact with the expansion restricting ring 16 when it is expanded by the expander ring 14.

[0047] The expansion restriction ring 16 is positioned on the same side as the wafer 1 attachment surface on the dicing tape 3 and is formed in a ring shape having an expansion restriction opening (opening) 16A that is smaller than the inner diameter of the frame 4 (350 mm) and larger than the outer diameter of the expand ring 14.

[0048] The expansion restriction ring 16 is positioned to move vertically between an expansion restriction position (a position that restricts the expansion of the outer peripheral region 3E: shown by the solid line in Figure 1) where the dicing tape 3 is in contact with the expansion of the dicing tape 3, and a retracted position (a position shown by the dashed line in Figure 1) which is retracted upward from the expansion restriction position. The outer peripheral region 3E will be described later.

[0049] Furthermore, the workpiece splitting device 10 is equipped with an expansion restricting ring moving mechanism 22 that moves the expansion restricting ring 16 between the expanded restricting position and the retracted position. An example of the expansion restricting ring moving mechanism 22 is an air cylinder device, but an actuator such as a lead screw device can also be used instead.

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

[0051] Here, the frame fixing member 7 is fixed to the fixing structure of the workpiece splitting device 10. As a result, the expansion restricting ring 16, which is positioned in the expansion restricting position and fixed to the frame fixing member 7 via the pin 24, is securely fixed in the expansion restricting position. As shown in Figure 3, which will be described later, when the dicing tape 3 expands, the annular portion 3B comes into contact with the expansion restricting ring 16, and the expansion of the outer peripheral portion 3E is restricted by the expansion restricting ring 16. For this reason, the expansion restricting ring 16 receives force from the annular portion 3B. At this time, if the expansion restricting ring 16 is displaced upward by the force from the annular portion 3B, it will not be possible to properly restrict the expansion of the outer peripheral portion 3E. However, in this embodiment, since the expansion restricting ring 16 is securely fixed to the frame fixing member 7 via the pin 24 in the expansion restricting position, displacement due to the force from the annular portion 3B can be prevented, and the expansion of the outer peripheral portion 3E can be properly restricted. Alternatively, instead of fixing the expansion restricting ring 16 to the frame fixing member 7 with the fixing member pin 24, the expansion restricting ring 16 may be fixed to the expansion restricting position by a fixing member (not shown).

[0052] Figure 3 is a longitudinal cross-sectional view of the wafer unit 2 showing the shape of the annular region 3B during expansion by the expanding ring 14.

[0053] As shown in Figure 3, when the annular region 3B is expanded by the expanding ring 14, the annular region 3B comes into contact with the expansion restricting ring 16. Specifically, the annular region 3B comes into contact with the inner edge 16B on the back side of the expansion restricting ring 16. In other words, the expansion restricting ring 16 comes into contact with the annular region 3B at a position outside the pressing position of the expanding ring 14.

[0054] In this embodiment, as shown in Figure 1, the diameter of the expansion-restricting 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-restricting 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.

[0055] Here, the inner circumference region 3F of the annular region 3B, whose expansion is not restricted by the expansion restricting ring 16, becomes the region that substantially contributes to the division of the wafer 1. That is, as the width dimension of the inner circumference region 3F decreases, the spring constant of the inner circumference region 3F increases, so the tension applied to the wafer 1 from the inner circumference region 3F can be increased. Therefore, it is preferable to set the width dimension of the inner circumference region 3F according to the division conditions defined by the number of division lines 5, etc.

[0056] The expansion retaining ring 18, which holds the expanded state of the dicing tape 3, is positioned on the back side of the dicing tape opposite to 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 of the frame 4 (350 mm) and whose inner diameter is larger than the outer diameter of the expand ring 14, and an elastically deformable ring-shaped fitting portion 30 attached to the outer circumference of the main ring 28, whose outer diameter (351.3 mm) is larger than the inner diameter of the frame 4 (350 mm).

[0057] Figure 4 is a longitudinal cross-sectional view showing the expanded state of the dicing tape 3 held by the expansion retaining ring 18. Figure 5 is an enlarged cross-sectional view of the main part of Figure 4.

[0058] 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 via the annular portion 3B of the dicing tape 3 at the fitting position shown by the solid line. As a result, the expanded state of the dicing tape 3 is held by the expansion retaining ring 18.

[0059] Before expansion and retention, the expansion retaining ring 18 is in a waiting position below the fitting position shown by the solid line in Figures 4 and 5 (the position shown by the solid line in Figure 1). When expansion and retention occurs, it is moved upward from the waiting position to the fitting position by the expansion retaining ring moving mechanism 32. As an example of the expansion retaining ring moving mechanism 32, a lead screw device is shown, 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 fitting portion 30 contacts the lower surface of the frame 4, and then the fitting portion 30 is pushed by the inner circumferential surface of the frame 4, causing it to rise while elastically deforming. The upward movement of the expansion retaining ring 18 stops when the fitting portion 30 has passed the inner circumferential surface of the frame 4. As a result, the fitting portion 30 is fitted to the surface 4A of the frame 4 at the fitting position as shown in Figures 4 and 5. Alternatively, the expansion retaining ring 18 may be fixed, and the dicing tape 3 side may be moved in a direction that brings it closer to the expansion retaining ring 18. In other words, the expansion retaining ring 18 is moved in a direction that brings it relatively closer to the dicing tape 3, and the fitting portion 30 is fitted onto the surface 4A of the frame 4.

[0060] 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 holding ring moving mechanism 32 that drives the expansion holding ring 18 are all controlled by a control unit 34 that comprehensively controls the workpiece splitting device 10, as shown in the block diagram of the control system in Figure 6.

[0061] The following describes an example of a workpiece division method performed by the control unit 34.

[0062] First, the control unit 34 controls the expansion restricting ring moving mechanism 22 to position the expansion restricting ring 16 in the expanded restricting 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 restricting ring moving mechanism 22 to move the expansion restricting ring 16 to the retracted position. Next, the control unit 34 controls the expansion holding ring moving mechanism 32 to move the expansion holding ring 18 to the fitted 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 workpiece splitting method described above will be specifically explained in reference to the flowchart in Figure 7 and the operation diagrams of the workpiece splitting device 10 shown in Figures 8(A) to (D) and 9(E) to (H).

[0064] First, in the arrangement process of step S100 in Figure 7, as shown in Figure 8(A), the expand ring 14 is moved to the retracted position by the expand ring moving mechanism 20, the expansion restricting ring 16 is moved to the expansion restricting position by the expansion restricting ring moving mechanism 22, and the expansion holding ring 18 is moved to the standby position by the expansion holding ring moving mechanism 32. At this time, the expansion restricting ring 16 is fixed to the frame fixing member 7 via the pin 24.

[0065] Next, in the fixing process of step S110 in Figure 7, the frame 4 of the wafer unit 2 is fixed to the frame fixing member 7 as shown in Figure 8(B).

[0066] Next, in the expansion start step S120 in Figure 7, as shown in Figure 8(C), the expander ring moving mechanism 20 moves the expander ring 14 upward in the direction of arrow B from the retracted position in Figure 8(A) toward the expanded position, thereby starting the expansion of the entire annular region 3B. The annular region 3B may be pre-cooled to a low temperature by a cooling means (not shown) to pre-increase the spring constant of the annular region 3B. Examples of cooling means include a contact type that cools by contacting the annular region 3B, or an air-cooling type that cools by injecting cold air into the annular region 3B.

[0067] Next, in the expansion restriction step S130 in Figure 7, as shown in Figure 8(D), when the upward movement of the expand ring 14 exceeds the thickness of the frame 4, the annular region 3B comes into contact with the expansion restriction ring 16. At this time, as shown in Figure 3, the annular region 3B is divided into an outer peripheral region 3E located on the outer circumference side and an inner peripheral region 3F located on the inner circumference side, with the contact portion 3D, which comes into contact with 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. Note that the expansion restriction step S130 is a step performed when the expansion process from the expansion start step S120 to the division step S140 is carried out. In other words, the expansion process includes the expansion start step S120, the expansion restriction step S130, and the division step S140.

[0068] Next, in the division process of step S140 in Figure 7, as shown in Figure 9(E), the upward movement of the expanding ring 14 is continued, and the inner peripheral region 3F of the annular region 3B, excluding the outer peripheral region 3E in Figure 3, is continued to expand, 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 fixing process is completed at this point.

[0069] In the splitting process of S140, during the expansion operation by the expand ring 14 after the annular region 3B comes into contact with the inner edge 16B of the expansion restricting ring 16, the expansion of the outer peripheral region 3E is restricted by the expansion restricting ring 16, while only the inner peripheral region 3F expands. In other words, a tension equal to the spring constant of the inner peripheral region 3F, which is larger than the spring constant of the annular region 3B, is applied to the wafer 1.

[0070] To explain in more detail, the length of the annular region 3B that contributes to the division of wafer 1 is shortened from 25 mm (width dimension of the annular region 3B) to 19 mm (width dimension of the inner circumference region 3F), so the spring constant increases inversely proportionally. As a result, even if only the inner circumference region 3F is expanded, the spring constant of the inner circumference region 3F is greater than the spring constant of the annular region 3B, so sufficient tension can be applied to wafer 1 to divide it into individual chips 6, even if the chip size is small (1 mm). Therefore, the workpiece division device 10 can resolve the problem of undivided planned division lines that occurs when the chip size is small (1 mm).

[0071] Furthermore, the inner edge 16B of the expansion regulating ring 16, which is in 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) as an example. This prevents the inner edge 16B and the annular region 3B from sliding relative to each other due to frictional force between them. In addition, the inner edge 16B is chamfered to a thickness of C0.2 as an example. This prevents the annular region 3B from tearing due to the reaction force when it receives an expansion force from the annular region 3B.

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

[0073] Next, in the expanded state holding step S160 in Figure 7, as shown in Figure 9(G), the expanded holding ring 18 is raised from the standby position to the fitting position by the expanded holding ring moving mechanism 32, and the fitting portion 30 of the expanded holding ring 18 is fitted to the surface 4A of the frame 4 at the fitting position to hold the expanded state of the dicing tape 3. That is, in the workpiece splitting device 10 of the embodiment, after the expansion step is performed, the expansion restricting ring retraction step S150 is performed, and after the expansion restricting ring retraction step S150 is performed, the expanded state holding step S160 is performed.

[0074] Next, in the expanding ring retraction step S170 in Figure 7, as shown in Figure 9(H), the expanding ring 14 is moved downward toward the retracted position by the expanding ring moving mechanism 22 and positioned in the retracted position. At this time, the dicing tape 3 is released from expansion by the expanding ring 14, but the expanded state is maintained without slack because the fitting portion 30 of the expansion holding ring 18 is fitted onto the surface 4A of the frame 4. This prevents contact between the chips 6 caused by the expanded dicing tape 3 slackening, thus preventing a deterioration in the quality of the chips 6.

[0075] As described above, the workpiece division method using the workpiece division device 10 of this embodiment can simultaneously resolve the problem of undivided lines in the planned division process, which occurs when the chip size is small, and the problem of chip quality degradation caused by contact between divided chips.

[0076] In the workpiece division method of this embodiment, after the expansion process from the expansion start step of S120 to the division step of S140 is performed, the expansion restricting ring retraction step of S150 is performed, and after the expansion restricting ring retraction step of S150 is performed, the expansion state holding step of S160 is performed, but the process is not limited to this. For example, after the expansion process from the expansion start step of S120 to the division step of S140 is performed, the expansion state holding step of S160 may be performed, and after the expansion state holding step of S160 is performed, the expansion restricting ring retraction step of S150 may be performed. 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 restricting ring 16 which is in the expansion restricting position. Therefore, in the embodiment, the expansion holding ring 18 cannot perform the expansion restricting ring retraction step S150 after the expansion state holding step S160. However, by using, for example, the tape expansion holding ring disclosed in Japanese Patent Application Publication No. 2009-253071, the expansion restricting ring retraction step S150 can be performed after the expansion state holding step S160. The tape expansion holding ring described in Japanese Patent Application Publication No. 2009-253071 is positioned on the same side as the wafer attachment surface of the dicing tape, and the tape expansion holding ring is pushed down from the raised position to the lowered position by a lifting mechanism. As a result, the expanded dicing tape is sandwiched between a ring located below the dicing tape and the tape expansion holding ring, and the expanded state is maintained. After this process of maintaining the expanded state, the expansion restricting ring retraction step S150 can be performed.

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

[0078] Here, we will describe the experimental results conducted by the inventors to confirm the effects of the present invention.

[0079] The graph in Figure 10 shows the expansion ratio of the annular region (diameter 350 mm) when the expansion restriction ring is not used, and the expansion ratio of the inner circumference 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, for the wafer unit 2 in Figure 13. In Figure 10, "MD (Machine Direction)" is the direction parallel to the feed direction during manufacturing of the dicing tape 3, and is the direction with a small spring constant. "CD (Cross Direction)" is the direction perpendicular to MD, and is the direction with a large spring constant.

[0080] According to the experimental results in Figure 10, the expansion rate of the annular region without using the expansion restriction ring was 6.1% for "MD" and 6.0% for "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% for "MD", and to 7.2%, 7.5%, and 8.1% for "CD". In other words, it was confirmed that the chip division capability improved as the diameter of the expansion restriction opening decreased.

[0081] The graph in Figure 11 shows the chip division ratio (diameter 350 mm) when the expansion restriction ring is not used for the wafer unit 2 in Figure 13, and the chip division ratio when the expansion restriction ring is used, with the diameter of the expansion restriction opening set to 338 mm. Note that the division ratio "with DAF" in Figure 11 is the division ratio of chip 6 when wafer 1 is attached to dicing tape 3 via DAF, and the division ratio "without DAF" is the division ratio of chip 6 when wafer 1 is attached directly to dicing tape 3.

[0082] According to the experimental results in Figure 11, the division rate of chip 6 without using an expansion restriction ring was 15.0% with DAF and 41.0% without DAF. In contrast, when using an expansion restriction ring with an expansion restriction opening diameter of 338 mm, the division rate of chip 6 increased to 61.0% with DAF and to 100% without DAF. In other words, it was confirmed that using an expansion restriction ring improves the division capability of chip 6, whether with or without DAF.

[0083] From the experimental results described above, it was confirmed that, according to the workpiece splitting apparatus 10 of the embodiment, 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, thereby increasing the expansion rate compared to the annular region 3B and increasing the tension applied to the wafer 1. This solves the problem of undivided planned splitting lines 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...Fixed region, 3D...Contact region, 3E...Outer peripheral region, 3F...Inner peripheral region, 4...Frame, 5...Division line, 6...Chip, 7...Frame fixing member, 8...Expanding ring, 10...Workpiece division device, 14...Expanding ring, 14A...Expansion opening, 16...Expansion restricting ring, 16A...Expansion restricting opening, 16B...Inner edge, 18...Expansion holding ring, 20...Expanding ring movement mechanism, 22...Expansion restricting ring movement mechanism, 24...Pin, 26...Hole, 28...Main ring, 30...Matching part, 32...Expansion holding ring movement mechanism, 34...Control unit

Claims

[Claim 1] In a workpiece division method 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, An expansion step is performed in which an expanding ring positioned on the back side of the dicing tape opposite to the surface to which the workpiece is attached is used to press the annular portion of the dicing tape that is inside the inner edge of the frame, thereby expanding the dicing tape. While the expansion step is being performed, an expansion restricting step is performed in which an expansion restricting ring, which is positioned on the same side of the dicing tape as the workpiece attachment surface, is brought into contact with a position in the annular region of the dicing tape that is outside the pressing position of the expand ring, thereby restricting the expansion of the outer peripheral region located on the outer peripheral side of the contact portion that is in contact with the expansion restricting ring within the annular region. An expanded state holding step is performed to hold the expanded state of the dicing tape expanded by the expansion step using an expansion holding ring, A workpiece division method comprising the following features.

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