WAFER PROCESSING PROCESS

Abstract

Wafer processing method for processing a wafer (11) which is provided on one side of a front surface (11a) with a component area (17a) in which a component (15) is formed in each of several areas subdivided by several roads (13) arranged in a grid pattern such that they intersect each other, which is provided on one side of a rear surface (11b) with a recess (19) formed in an area corresponding to the component area (17a), and which is provided on a circumferential section with an annular reinforcement section (21) surrounding the component area (17a) and the recess (19), wherein the wafer processing method comprises: a tape application step of applying a pressure-sensitive adhesive tape (23) to the side of the rear surface (11b) of the wafer (11) along the depression (19) and the reinforcement section (21); a holding step of holding a floor surface (19a) of the depression (19) by a first clamping table (4) by the pressure-sensitive adhesive strip (23); a cutting step of cutting the wafer (11) along the roads (13) by a cutting blade (16) in order to divide the component area (17a) into several component chips (27) and to form cutting grooves (11c) in the reinforcement section (21); a division step of applying an external force to the reinforcement section (21) in order to divide the reinforcement section (21) with the cutting grooves (11c) as starting points; and a removal step of an ejection of fluid in the direction of the reinforcement section (21) from a predetermined ejection position located on an outside of the wafer (11) in order to distribute the split reinforcement section (21) in the direction of a side opposite the ejection position and to remove the split reinforcement section (21).

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to a wafer processing method. Description of the state of the art

[0002] In a process for manufacturing electronic component chips, a wafer is used that has a component area on one side of a front surface. Within this component area, a component is formed in each of several regions, which are divided by multiple streets arranged in a grid pattern. By dividing the wafer along these streets, multiple component chips, each containing a single component, are obtained. These component chips are used in various electronic devices, such as mobile phones and PCs.

[0003] In recent years, the trend towards smaller electronic devices has led to a demand for thinner component chips. Against this backdrop, the wafer could be subjected to a thinning process before being split. This process utilizes a grinding fixture consisting of a clamping table for holding the workpiece and a grinding unit with a grinding wheel and multiple grinding stones. The wafer is held by the clamping table, and the grinding stones are brought into contact with one side of the wafer's rear surface while the clamping table and grinding wheel are rotated, thus grinding and thinning the wafer.

[0004] When a wafer is thinned by grinding, its stiffness is reduced, potentially leading to damage during post-grinding handling (transportation, etc.). In light of this, a method has been proposed in which only a portion of the wafer's back surface, intersecting with the device area, is thinned by grinding (see Japanese patent application JP 2007-19379A). Using this method, while a central section of the wafer is thinned to form a depression, a circumferential section remains thicker, retaining its original thickness and thus acting as an annular reinforcement. Consequently, a decrease in wafer stiffness after grinding is prevented.

[0005] The wafer, designed to be this thin, is then divided into multiple device chips, for example, using a cutting device that cuts a workpiece with an annular cutting blade. In this case, the wafer is cut along the edges after the annular reinforcement section remaining on the circumferential section has been removed. For example, Japanese patent application JP 2011-61137A discloses a method in which a circumferential section of the wafer is cut in an annular shape by a cutting blade to separate the reinforcement section (annular projection) from the device area, and the reinforcement section is then lifted and removed by a claw assembly having multiple claws.

[0006] Further prior art that is helpful for understanding the present invention can be found in the following documents: JP 2014- 207 386 A relates to a wafer processing method that is able to inhibit the occurrence of chipping.

[0007] DE 10 2016 111 629 A1 relates to a method for manufacturing a semiconductor device. SUMMARY OF THE INVENTION

[0008] As described above, the annular reinforcement section remaining on the wafer's periphery is separated and removed during the wafer processing process. However, immediately after separation, the reinforcement section is positioned near the device area, surrounding the central section (device area) of the wafer in a thin, less stiff state. Therefore, during removal, the annular reinforcement section could inadvertently touch the device area and damage it.

[0009] To properly remove the reinforcement section, a process is required in which the reinforcement section is carefully held and lifted to prevent any vibration or positional deviation, thus ensuring that the reinforcement section does not come into contact with the component area. Consequently, the design of the mechanism used for removing the reinforcement section (claw assembly, etc.) is complex, increasing costs. Additionally, the process time required for removing the reinforcement section is extended, and the process efficiency is reduced.

[0010] The present invention was developed in consideration of these problems. An objective of the present invention is to provide a wafer processing method by which a reinforcement section remaining on a circumferential section of a wafer can be easily removed.

[0011] According to one aspect of the present invention, a wafer processing method is provided for processing a wafer which is provided on one side of a front surface with a component area in which a component is formed in each of several areas subdivided by several streets arranged in a grid pattern such that they intersect one another, which is provided on one side of a rear surface with a recess formed in an area corresponding to the component area, and which is provided on a circumferential section with an annular reinforcement section surrounding the component area and the recess. The wafer processing method comprises a tape application step of applying a pressure-sensitive adhesive tape to the side of the rear surface of the wafer along the recess and the reinforcement section.a holding step of holding a bottom surface of the depression by a first clamping table by the pressure-sensitive adhesive strip, a cutting step of cutting the wafer along the roads by a cutting blade to divide the device area into several device chips and to form cutting grooves in the reinforcement section, a division step of applying an external force to the reinforcement section to divide the reinforcement section with the cutting grooves as starting points, and a removal step of ejecting fluid towards the reinforcement section from a predetermined ejection position located on an outside of the wafer to distribute the divided reinforcement section towards a side opposite the ejection position and to remove the divided reinforcement section.

[0012] Note that preferably in the removal step, the fluid is ejected along a tangential direction along a circumferential edge of the wafer. Additionally, preferably in the division step, in a state where the wafer is supported by a second clamping table that has projections and depressions at a position corresponding to the reinforcement section of the wafer, the pressure-sensitive adhesive strip is drawn through the second clamping table to arrange the pressure-sensitive adhesive strip along the projections and depressions and to divide the reinforcement section.In addition, preferably in the removal step, in a state in which a nozzle and a collecting mechanism are arranged such that the reinforcement section of the wafer is arranged between them, the fluid is ejected from the nozzle to the reinforcement section in order to distribute the split reinforcement section to the collecting mechanism and to collect the split reinforcement section by the collecting mechanism.

[0013] In the wafer processing method according to one mode of the present invention, the device area is divided into several device chips in the cutting step, and cutting grooves are formed in the reinforcement area. Then, in the splitting step, an external force is applied to the reinforcement section to split it, with the cutting grooves serving as the starting points. Consequently, the reinforcement section can be easily removed from the wafer by a simple process of ejecting the fluid to the split reinforcement section.

[0014] Additionally, in the wafer processing method according to one mode of the present invention, the divided reinforcement section (the multiple chips) is distributed towards the side opposite the ejection position by ejecting the fluid towards the reinforcement section from a predetermined ejection position located on the outside of the wafer. Consequently, random distribution of the chips from the wafer can be prevented, and chip collection is facilitated.

[0015] The above and other problems, features and advantages of the present invention and its implementation will best become clearer by studying the following description and attached claims, with reference to the attached drawings, which show a preferred embodiment of the invention, and the invention will be best understood thereby. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A is a perspective view showing one side of a front surface of a wafer; Fig. 1B is a perspective view showing one side of a rear surface of the wafer; Fig. 2A is a perspective view showing the wafer with a pressure-sensitive adhesive tape attached to it; Fig. 2B is a sectional view showing the wafer with the pressure-sensitive adhesive tape attached to it; Fig. Figure 3 is a perspective view depicting a cutting device; Fig. 4 is a sectional view showing the wafer held by a clamping table; Fig. 5A is a sectional view showing the wafer cut along a first direction; Fig. 5B is a sectional view showing the wafer cut along a second direction; Fig. Figure 6 is a perspective view showing a unit for exerting an external force; Fig. 7A is a sectional view showing the wafer arranged on the clamping table; Fig. 7B is a sectional view showing the wafer sucked in by the clamping table; Fig. Figure 8 is a perspective view showing the wafer where a reinforcement section is divided into multiple chips; and Fig. Figure 9 is a perspective view showing the wafer at one distance step. DETAILED DESCRIPTION OF THE PREFERRED VERSION

[0016] An embodiment of the present invention is described below with reference to the accompanying drawings. First, an example of a wafer to be processed by the wafer processing method according to the present embodiment is described. Fig. 1A is a perspective view showing one side of a front surface of a wafer 11, and Fig. 1B is a perspective view showing one side of a rear surface of wafer 11.

[0017] The wafer 11, for example, is a disk-shaped substrate made of a semiconductor such as silicon and has a front surface 11a and a rear surface 11b that are substantially parallel to each other. The wafer 11 is subdivided into several rectangular regions by several roads 13 arranged in a grid pattern such that they intersect each other. Additionally, in each of the regions subdivided by the roads 13, a device 15, such as an integrated circuit (IC), a large-scale integration (LSI), a light-emitting diode (LED), or a microelectromechanical system (MEMS), is formed on the side of the front surface 11a of the wafer 11. On the side of the front surface 11a of the wafer 11, there is a substantially circular device region 17a in which several devices 15 are formed, and an annular circumferential border region 17b that surrounds the device region 17a.The circumferential border region 17b corresponds to an annular region with a predetermined width (for example, on the order of 2 mm), including a circumferential border of the front surface 11a. In . Fig. 1A is the boundary between the component area 17a and the peripheral edge area 17b indicated by a line with alternating long and two short dashes. Note that there are no restrictions regarding the material, shape, structure, size, and the like of the wafer 11. For example, the wafer 11 could be a substrate made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramic, plastic, metal, or the like. Additionally, there are no restrictions regarding the type, number, shape, structure, size, arrangement, and the like of the components 15.

[0018] By dividing the wafer 11 in a grid pattern along roads 13, several component chips are produced, each containing the component 15. Additionally, thin component chips can be obtained by subjecting the wafer 11 to a thinning process prior to dividing. For thinning the wafer 11, for example, a grinding device is used. The grinding device has a clamping table (holding table) that holds the wafer 11 and a grinding unit that grinds the wafer 11. A ring-shaped grinding wheel with several grinding stones is attached to the grinding unit. While the wafer 11 is held by the clamping table, the grinding stones are brought into contact with the side of the back surface 11b of the wafer 11 while the clamping table and the grinding wheel are rotated, thus grinding the side of the back surface 11b of the wafer 11 and thinning the wafer 11.

[0019] Note that if the entire portion of the back surface 11b of the wafer 11 is ground, the entire portion of the wafer 11 will be thinned, resulting in a decrease in the stiffness of the wafer 11. This could lead to damage to the wafer 11 if it is handled (transported, etc.) after grinding. Therefore, the thinning process (grinding) should only be applied to a central section on the back surface 11b of the wafer 11.

[0020] For example, as in Fig. As shown in Figure 1B, only a central section on the side of the rear surface 11b of the wafer 11 is ground and thinned. Consequently, a circular recess (groove) 19 is formed in the rear surface 11b of the wafer 11. Note that the recess 19 is positioned corresponding to the component area 17a. For example, the size (diameter) of the recess 19 is specified to be substantially equal to the size (diameter) of the component area 17a, and the recess 19 is designed to overlap with the multiple components 15. The recess 19 has a side surface (inner wall) 19b that is substantially parallel to the front surface 11a and the rear surface 11b of the wafer 11 and an annular side surface (inner wall) 19b that is substantially perpendicular to the bottom surface 19a and is connected to the bottom surface 19a and the rear surface 11b.A ring-shaped reinforcement section (protrusion) 21 remains on a circumferential section of the wafer 11, corresponding to an area that is not subjected to the thinning process (grinding process). The reinforcement section 21 has the circumferential edge region 17b and surrounds the component area 17a and the recess 19.

[0021] If only a central section of the wafer 11 is made thin, a circumferential section (reinforcement section 21) of the wafer 11 is kept in a thick state. As a result, a decrease in the stiffness of the wafer 11 is inhibited, and damage to the wafer 11 or similar occurrences are not likely. In other words, the reinforcement section 21 acts as a reinforcement area to strengthen the wafer 11.

[0022] Next, a specific example of the wafer processing method for dividing wafer 11 into multiple component chips is described. In the present embodiment, a pressure-sensitive adhesive tape is first applied to the side of the rear surface 11b of wafer 11 (tape application step). Fig. 2A is a perspective view showing the wafer 11 with an adhesive tape 23 attached to it, and Fig. Figure 2B is a sectional view showing the wafer 11 with the adhesive tape 23 attached to it.

[0023] The pressure-sensitive adhesive strip 23 is attached to the rear surface 11b of the wafer 11 and is sized to cover the entire side of the rear surface 11b of the wafer 11. For example, the circular pressure-sensitive adhesive strip 23, which has a diameter larger than that of the wafer 11, is attached to cover the side of the rear surface 11b of the wafer 11. The pressure-sensitive adhesive strip 23 can be a flexible film comprising a circular substrate and an adhesive layer applied to the substrate. For example, the substrate is made of a plastic such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the pressure-sensitive adhesive layer is made of an epoxy, acrylic, or rubber-based adhesive.Additionally, a plastic of the ultraviolet (UV) curing type can also be used as the pressure-sensitive adhesive layer, which is hardened when irradiated with UV rays.

[0024] The pressure-sensitive adhesive tape 23 is applied along the contour of the side of the back surface 11b of the wafer 11. In other words, as shown in Fig. As shown in Figure 2B, the pressure-sensitive adhesive strip 23 is attached along the bottom surface 19a and the side surface 19b of the recess 19 and a rear surface (bottom surface) of the reinforcement section 21. Note that in Fig. Figure 2B shows an example in which the pressure-sensitive adhesive strip 23 is in close contact with the bottom surface 19a and the side surface 19b, but a slight gap may exist between the pressure-sensitive adhesive strip 23 and a circumferential section of the bottom surface 19a or between the pressure-sensitive adhesive strip 23 and the side surface 19b.

[0025] An annular frame 25, made of metal such as stainless steel (SUS), is attached to a circumferential section of the pressure-sensitive adhesive strip 23. The frame 25 has a circular opening 25a at its central section, capable of receiving the wafer 11. The wafer 11 is supported by the frame 25 through the pressure-sensitive adhesive strip 23 in a position where it is located within the opening 25a. Consequently, the wafer 11, the pressure-sensitive adhesive strip 23, and the frame 25 form a frame unit in which they are interconnected (processing arrangement).

[0026] The wafer 11 with the pressure-sensitive adhesive tape 23 attached to it is cut by a cutting device. Fig. Figure 3 is a perspective view depicting a cutting device 2. In Fig. Three directions are perpendicular to each other: an X-axis direction (processing feed direction, first horizontal direction) and a Y-axis direction (index feed direction, second horizontal direction). Additionally, a Z-axis direction (vertical direction, up-down direction, height direction) is a direction perpendicular to both the X-axis and Y-axis directions. The cutting device 2 comprises a clamping table (holding table) 4, which holds the wafer 11, and a cutting unit 12, which cuts the wafer 11 held by the clamping table 4.

[0027] An upper surface of the clamping table 4 is a flat surface that is essentially parallel to the X-axis direction and the Y-axis direction, and forms a circular holding surface 4a (see Fig. 4), which holds the wafer 11. Additionally, a ball screw-type motion mechanism (not shown) that moves the clamping table 4 along the X-axis direction, and a rotary drive source (not shown), such as a motor, that rotates the clamping table 4 about an axis of rotation substantially parallel to the Z-axis direction, are connected to the clamping table 4.

[0028] The cutting unit 12 for cutting the wafer 11 is arranged on an upper side of the clamping table 4. The cutting unit 12 has a hollow cylindrical housing 14, and a cylindrical spindle (not shown) arranged along the Y-axis direction is housed in the housing 14. A tip section (one end section) of the spindle is exposed to the outside of the housing 14, and a rotary drive source (not shown), such as a motor, is connected to a base end section (the other end section) of the spindle.

[0029] An annular cutting blade 16 is mounted at the tip section of the spindle. The cutting blade 16 is rotated about an axis of rotation substantially parallel to the Y-axis direction by power transmitted from the rotary drive source via the spindle. For example, a hub-type cutting blade (hub blade) is used as the cutting blade 16. The hub blade has an annular base made of metal or similar material and an annular cutting edge formed along a circumferential edge of the base, which are connected to each other. The cutting edge of the hub blade has an electro-cast grinding wheel in which abrasive grains made of diamond or similar material are fixed by a bonding agent such as a nickel plating layer. Alternatively, a disc-type cutting blade (disc blade) could also be used as the cutting blade 16.The disc blade has a ring-shaped cutting edge in which abrasive grains made of diamond or similar material are fixed by a bonding agent such as metal, ceramic or plastic.

[0030] The cutting blade 16, attached to the tip section of the spindle, is covered by a blade cover 18, which is fixed to the housing 14. The blade cover 18 has a connecting section 20, which is connected to a tube (not shown) to which a liquid (cutting fluid), such as pure water, is supplied, and a pair of nozzles 22, which are connected to the connecting section 20 and are arranged on both surface sides (front and rear surfaces) of the cutting blade 16. The pair of nozzles 22 are designed with ejection openings (not shown) that open towards the cutting blade 16. When the wafer 11 is cut by the cutting blade 16, the cutting fluid is supplied to the connecting section 20 and is ejected from the ejection openings of the pair of nozzles 22 towards both surfaces (front and rear surfaces) of the cutting blade 16.Consequently, the wafer 11 and the cutting blade 16 are cooled and the abrasion produced by cutting (cutting abrasion) is washed away.

[0031] A ball screw motion mechanism (not shown) for moving the cutting unit 12 is connected to the cutting unit 12. The motion mechanism moves the cutting unit 12 along the Y-axis direction and raises and lowers the cutting unit 12 up and down along the Z-axis direction.

[0032] At the time of cutting the wafer 11, the wafer 11 is first held by the clamping table 4 (first clamping table) (holding table). Fig. Figure 4 is a sectional view showing the wafer 11 held by the clamping table 4.

[0033] The clamping table 4 has a cylindrical frame body (main body section) 6 made of metal, glass, ceramic, plastic, or the like. The frame body 6 has a recess (groove) 6b on one side of an upper surface 6a, which is circular in plan view, and a disc-shaped retaining element 8 is fitted into the recess 6b. The retaining element 8 is made of a porous material, such as a porous ceramic, and has a free space (intake passage) that connects an upper surface with a lower surface of the retaining element 8. The upper surface 6a of the frame body 6 and an upper surface 8a of the retaining element 8 are arranged essentially in the same plane and form the holding surface 4a of the clamping table 4. Additionally, the upper surface 8a of the retaining element 8 forms a circular intake surface for drawing in the wafer 11.The holding surface 4a is connected to a suction source (not shown) such as an ejector via a channel (not shown) formed inside the holding element 8 and the frame body 6, a valve (not shown) and the like.

[0034] The wafer 11 is positioned on the clamping table 4 such that the side of the front surface 11a is exposed at the top. Note that the clamping table 4 is designed to hold the bottom surface 19a of the recess 19 of the wafer 11 by means of the holding surface 4a. In particular, the diameter of the holding surface 4a is smaller than the diameter of the recess 19, and the side of the holding surface 4a of the clamping table 4 is fitted into the recess 19. Consequently, the bottom surface 19a of the recess 19 is supported by the holding surface 4a through the pressure-sensitive adhesive strip 23. Additionally, several clamps 10 are provided around the circumference of the clamping table 4 for clamping and securing the frame 25. After the wafer 11 is positioned on the clamping table 4, the frame 25 is secured by the multiple clamps 10.When the wafer 11 is positioned on the clamping table 4, a suction force (negative pressure) from the suction source is applied to the holding surface 4a, a portion of the pressure-sensitive adhesive strip 23, which is attached to the bottom surface 19a of the recess 19, is drawn into the holding surface 4a. Consequently, the bottom surface 19a of the recess 19 is held under suction by the clamping table 4 via the pressure-sensitive adhesive strip 23.

[0035] Next, the wafer 11 is cut by the cutting blade 16 along the roads 13 (see Fig. 3 and the like) cut (cutting step). In the cutting step, the wafer 11 is cut along the roads 13 parallel to the first direction and the roads 13 parallel to the second direction, which intersects the first direction.

[0036] Fig. 5A is a sectional view showing wafer 11 cut along the first direction.

[0037] First, the clamping table 4 is rotated to align the longitudinal direction of a path 13 parallel to the first direction with the X-axis direction. Additionally, the position of the cutting unit 12 in the Y-axis direction is adjusted so that the cutting blade 16 is positioned on an extension line of the path 13. Furthermore, the height of the cutting unit 12 is adjusted so that the lower end of the cutting blade 16 is located below the bottom surface 19a of the recess 19. For example, the lower end of the cutting blade 16 is positioned below the upper surface of the pressure-sensitive adhesive strip 23 attached to the bottom surface 19a of the recess 19, but above the holding surface 4a (the lower surface of the pressure-sensitive adhesive strip 23). In this case, the height difference between the front surface 11a of the wafer 11 and the lower end of the cutting blade 16 corresponds to the cutting depth of the cutting blade 16 into the wafer 11.

[0038] Then, while the cutting blade 16 is rotated, the clamping table 4 is moved in the X-axis direction. Consequently, the clamping table 4 and the cutting blade 16 are set into relative motion along the X-axis direction (machining feed), and the cutting blade 16 cuts along a single path 13 into the side of the front surface 11a of the wafer 11. The cutting depth of the cutting blade 16 is, in this case, greater than the thickness of the central section (element area 17a) of the wafer 11, but less than the thickness of the circumferential section (reinforcement section 21) of the wafer 11. Therefore, an opening (seam) is formed in the element area 17a of the wafer 11 along a single path 13, extending from the front surface 11a to the bottom surface 19a. On the other hand, in the reinforcement section 21 of the wafer 11, a cutting groove 11c is formed along one road 13 with a depth corresponding to the cutting depth of the cutting blade 16.

[0039] The cutting blade 16 is then moved by an interval of the roads 13 in the Y-axis direction (indexing), and the wafer 11 is cut along another road 13. By repeating this process, the wafer 11 is cut along all roads 13 parallel to the first direction.

[0040] Next, the clamping table 4 is rotated by 90° to align the longitudinal direction of the roads 13 parallel to the second direction with the X-axis direction. Then, the wafer 11 is cut along all roads 13 parallel to the second direction in a similar manner to that described above. Fig. 5B is a sectional view showing wafer 11 cut along the second direction.

[0041] After the wafer 11 has been cut along all roads 13, the component area 17a of the wafer 11 is divided along the roads 13, resulting in several component chips 27 (see Fig. 6) are obtained, each having the component 15. In addition, cutting grooves 11c are formed along the roads 13 on one side of an upper surface (front surface) of the reinforcement section 21.

[0042] Subsequently, an external force is exerted on the reinforcement section 21 to divide it, with the cutting grooves 11c serving as starting points (division step). In the present embodiment, the external force is exerted by the pressure-sensitive adhesive strip 23 being drawn onto the reinforcement section 21 by the second clamping table.

[0043] Fig. Figure 6 is a perspective view showing a unit 30 for exerting an external force. The unit 30 for exerting an external force is a mechanism for applying an external force to the wafer 11 and is provided inside or outside the cutting device 2 (see Figure 6). Fig. 3) The unit 30 for exerting an external force has a clamping table (holding table) 32 which holds the wafer 11.

[0044] An upper surface of the clamping table 32 forms a circular holding surface for holding the wafer 11. Additionally, a rotary drive source (not shown), such as a motor, is connected to the clamping table 32 for rotating it about an axis of rotation substantially parallel to the vertical direction. The clamping table 32 has a cylindrical frame body (main body section) 34, which is made of metal, glass, ceramic, plastic, or the like. In a central section on one side of an upper surface 34a of the frame body 34, a recess (groove) 34b is formed, which is circular in a top view, and a disc-shaped retaining element 36 is fitted into the recess 34b.The retaining element 36 is made of a porous material, such as a porous ceramic, and has a free space (intake passage) that connects an upper surface with a lower surface of the retaining element 36. An upper surface of the retaining element 36 forms a circular intake surface 36a for holding the wafer 11 under suction. The intake surface 36a is arranged essentially in the same plane as the upper surface 34a of the frame body 34.

[0045] The clamping table 32 is provided with projections and recesses at a position corresponding to the reinforcement section 21 of the wafer 11. For example, the frame body 34 is designed such that its upper surface 34a overlaps the reinforcement section 21 when the wafer 11 is positioned on the clamping table 32. Additionally, several projections (protuberances) 38 are provided on the side of the upper surface 34a of the frame body 34, projecting upwards from the upper surface 34a. Note that in Fig. Figure 6 shows the projections 38, which are formed in a rectangular parallelepiped shape, but there is no restriction regarding the shape of the projections 38. The multiple projections 38 are arranged at substantially regular intervals along the circumferential direction of the frame body 34. Then the upper surface 34a of the frame body 34 and the projections 38 form an annular region that has periodic projections and depressions.

[0046] Furthermore, annular grooves 40a and 40b are formed on the side of the upper surface 34a of the frame body 34, opening into the upper surface 34a. For example, the grooves 40a and 40b are formed concentrically on both sides of the multiple projections 38 (on the outside and inside in the radial direction of the frame body 34). In addition, the grooves 40a and 40b are connected to each other via several grooves 40c formed along the radial directions of the frame body 34.

[0047] The retaining element 36 is connected to a suction source 44 via a channel (not shown) provided inside the frame body 34 and via a valve 42a. Additionally, the grooves 40a, 40b, and 40c are connected to the suction source 44 via a channel (not shown) provided inside the frame body 34 and via a valve 42b. An ejector, for example, could be used as the suction source 44.

[0048] The wafer 11 is positioned on the clamping table 32 such that the reinforcement section 21 overlaps the upper surface 34a of the frame body 34. This allows the reinforcement section 21 of the wafer 11 to be supported by the pressure-sensitive adhesive strip 23 via the multiple projections 38.

[0049] Fig. Figure 7A is a sectional view showing the wafer 11 arranged on the clamping table 32. Note that in Fig. 7A For the sake of simplicity, only the shapes of sections of the wafer 11, the pressure-sensitive adhesive strip 23, the frame 25, and the clamping table 32 are shown. When the valves 42a and 42b are opened in a state where the wafer 11 is positioned on the clamping table 32, the suction force (negative pressure) of the suction source 44 acts on the suction surface 36a and the grooves 40a, 40b, and 40c, so that the wafer 11 is held under suction by the clamping table 32 through the pressure-sensitive adhesive strip 23.

[0050] Fig. Figure 7B is a sectional view showing the wafer 11 being drawn in by the clamping table 32. A region of the pressure-sensitive adhesive strip 23, which is attached to the multiple component chips 27, is drawn in by the suction surface 36a and comes into contact with it. Additionally, a region of the pressure-sensitive adhesive strip 23, which is attached to the side of the rear surface 11b of the circumferential section (reinforcement section 21) of the wafer 11, and its adjacent region are drawn in through the grooves 40a and 40b and come into contact with the upper surface 34a of the frame body 34.

[0051] Here are, as in Fig. As shown in Figure 6, periodic projections and depressions are formed on the side of the upper surface 34a of the frame body 34 by the multiple projections 38 in the ring shape. Therefore, when the negative pressure is caused to act on the grooves 40a and 40b, a region of the pressure-sensitive adhesive strip 23, which is attached to the circumferential section of the wafer 11, is deformed along the upper surface 34a of the frame body 34 and the projections 38, assuming a corrugated state. Then, regions of the reinforcement section 21 that are not supported by the projections 38 are drawn by the pressure-sensitive adhesive strip 23 to the side of the upper surface 34a of the frame body 34 and move to penetrate between the adjacent projections 38. Consequently, a shear force acts on the reinforcement section 21.In other words, when the pressure-sensitive adhesive strip 23 is drawn into the clamping table 32, an external force is exerted on the reinforcement section 21. When the external force is exerted on the reinforcement section 21, cracks are generated by the cutting grooves 11c formed in the reinforcement section 21, which develop in the thickness direction of the reinforcement section 21. Consequently, the reinforcement section 21 fractures along the grooves 13. In other words, the cutting grooves 11c act as splitting points of the reinforcement section 21, and the annular reinforcement section 21 is divided into several chips along the grooves 13.

[0052] Fig. Figure 8 is a perspective view showing wafer 11, where the reinforcement section 21 is divided into several chips 29. As in Fig. Figure 8 shows that of the several chips 29 formed by dividing the reinforcement section 21, the chips 29 formed by the projections 38 (see Fig. 6 and the like) of the clamping table 32 are arranged so that they are positioned upwards in comparison to the other chips 29 and the component chips 27.

[0053] Note that in the division step, it is not necessary to divide the reinforcement section 21 along all cutting grooves 11c. In particular, it is sufficient to divide the reinforcement section 21 into several chips that are equal to or smaller than a predetermined size, so that the reinforcement section 21 can be appropriately removed in a later removal step. Additionally, in Fig. Although an example is described in Figure 6 where the projections and recesses of the clamping table 32 are formed from the upper surface 34a of the frame body 34 and the projections 38, there is no restriction regarding the method for forming the projections and recesses. For example, the projections and recesses could be formed by providing several recesses (grooves) on the side of the upper surface 34a of the frame body 34. Furthermore, the method for exerting an external force on the reinforcement section 21 is not limited to the suction of the pressure-sensitive adhesive strip 23 by the clamping table 32. For example, the external force could be exerted on the reinforcement section 21 by pressing a pressure element against the reinforcement section 21 in a state in which the wafer 11 is held by a predetermined clamping table.Additionally, a band (expansion band) could be used as the pressure-sensitive adhesive band 23, which can be expanded by applying an external force to it, and the external force could be applied to the reinforcement section 21 by pulling and expanding the expansion band.

[0054] Next, the reinforcement section 21, which is divided into several chips 29, is removed (removal step). In the removal step, the several chips 29 formed by dividing the reinforcement section 21 are peeled off the pressure-sensitive adhesive strip 23 and removed. Fig. Figure 9 is a perspective view showing the wafer 11 during the removal step. For example, a nozzle 46 for ejecting fluid 48 and a collection mechanism 50 for collecting the reinforcement section 21 (chips 29) are arranged around the circumference of the wafer 11 held by the clamping table 32 (see Figure 9). Fig. 6 and the like).

[0055] The nozzle 46 is attached to a predetermined ejection position located on the radially outer side of the wafer 11 with respect to the wafer's circumferential edge. A fluid supply source (not shown) for supplying the fluid 48 to the nozzle 46 is connected to the nozzle 46. The nozzle 46 also has an ejection orifice 46a for ejecting the fluid 48 supplied by the fluid supply source. Note that the fluid 48 ejected by the nozzle 46 is not limited to any particular type. For example, gas, such as air, could be used. Additionally, a liquid (high-pressure fluid), such as pressurized pure water, or a mixed fluid containing liquid (pure water, etc.) and gas (air, etc.), could be used as the fluid 48.For example, the nozzle 46 is arranged at essentially the same height as the wafer 11, such that the ejection orifice 46a faces the circumferential section (reinforcement section 21) of the wafer 11. Additionally, the direction of the nozzle 46 is adjusted so that the ejection orifice 46a intersects a line tangential to the circumferential edge of the wafer 11. Consequently, the fluid 48 is ejected along the tangential direction of the circumferential edge of the wafer 11.

[0056] For example, the collection mechanism 50 is a container having an opening 50a that opens towards the side of the ejection orifice 46a of the nozzle 46. The nozzle 46 and the collection mechanism 50 are arranged such that the reinforcement section 21 of the wafer 11 is positioned between them. For example, the nozzle 46 and the collection mechanism 50 are positioned on a tangential line to the circumferential edge of the wafer 11. Consequently, the reinforcement section 21 is located between the ejection orifice 46a of the nozzle 46 and the opening 50a of the collection mechanism 50.

[0057] In the removal step, the fluid 48 is ejected from the nozzle 46, while the clamping table 32 (see Fig. 6 and the like), which holds the wafer 11, is rotated at a low speed (for example, 5 to 10 rpm). Consequently, the fluid 48 is ejected from the ejection position (the position of the nozzle 46) located on the outside of the wafer 11 in the direction of the reinforcement section 21. As a result, pressure is exerted on the reinforcement section 21 by the fluid 48, and the split reinforcement section 21 (chips 29) is detached from the pressure-sensitive adhesive strip 23. The split reinforcement section 21 (chips 29) is spread out on the side opposite the ejection position of the fluid 48. When the wafer 11 is rotated one revolution in a state where the fluid 48 is ejected from the nozzle 46, the fluid 48 is ejected onto the entire area of ​​the reinforcement section 21, and all chips 29 are peeled off the pressure-sensitive adhesive tape 23.Consequently, the reinforcement section 21 is removed, leaving only several component chips 27 on the pressure-sensitive adhesive tape 23.

[0058] Thus, since in the present embodiment the annular reinforcement section 21 is divided into the multiple chips 29 in the division step, the reinforcement section 21 can be easily removed in the removal step by applying only an appropriate external force to each of the chips 29. Consequently, the preparation and operation of a precise conveying mechanism for transporting the annular reinforcement section 21 are unnecessary, and the removal process for the reinforcement section 21 is simplified.

[0059] Additionally, as in Fig. Figure 9 shows that the chips 29 are distributed in one direction from the wafer 11 when the ejection position of the fluid 48 (the position of the nozzle 46) is fixed on the outside of the wafer 11. Consequently, a distribution of the chips 29 in random directions from the wafer 11 can be prevented, and the collection of the chips 29 is facilitated.

[0060] Furthermore, if the collection mechanism 50 is arranged such that it faces the nozzle 46, the chips 29, dispersed by the ejection of the fluid 48, are introduced into the opening 50a of the collection mechanism 50 and enter the collection mechanism 50. In other words, the chips 29 are removed and collected. Consequently, a separate process of collecting the chips 29 dispersed after the collection step becomes unnecessary, and operational efficiency is improved. Note that the type of collection mechanism 50 is not limited to any particular design. For example, the collection mechanism 50 could be a channel connected to a suction source, such as an ejector. In this case, the fluid 48 is ejected from the nozzle 46, and a suction force (vacuum) from the suction source is applied to the channel, thereby reliably introducing the dispersed chips 29 into the channel.

[0061] As described above, in the processing method according to the present embodiment, the component area 17a is divided into several component chips 27 during the cutting step, and the cutting grooves 11c are formed in the reinforcement section 21. Then, in the division step, an external force is applied to the reinforcement section 21 to divide it, with the cutting grooves 11c serving as the starting points. Consequently, the reinforcement section 21 can be easily removed from the wafer 11 by a simple process of ejecting the fluid 48 from the divided reinforcement section 21.

[0062] Additionally, in the wafer processing method according to the present embodiment, the fluid 48 is ejected from a predetermined injection position located on the outside of the wafer 11 towards the reinforcement section 21, thereby distributing the divided reinforcement section 21 (the multiple chips 29) in the direction opposite the ejection position. Consequently, the chips 29 cannot be distributed randomly from the wafer 11, and their collection is facilitated.

[0063] Note that in the removal step, the reinforcement section 21 could be removed by alternately ejecting the fluid 48 and rotating the clamping table 32. Specifically, with the clamping table 32 stationary, the fluid 48 is first ejected onto a portion of the reinforcement section 21. Then, the clamping table 32 is rotated by a predetermined angle, and the fluid 48 is again ejected onto a portion of the reinforcement section 21. This process is repeated until the wafer 11 has been rotated one full turn, thereby removing all chips 29 from the pressure-sensitive adhesive tape 23. Additionally, during the removal step, the multiple component chips 27 could be covered with a protective film. For example, pure water could be supplied from above the clamping table 32 towards the wafer 11, and the multiple component chips 27 could be covered with a layer of water.Consequently, it is not likely that the component chips 27 will be damaged, even if the chips 29 were to be distributed to the side of the component chips 27. Furthermore, while an example has been described in the present embodiment in which the division step and the removal step are performed using the same clamping table 32 (see . Fig. 6 and the like), the wafer 11 is held by different clamping tables in the division step and in the removal step.

[0064] Furthermore, the structures, methods and the like relating to the above embodiment could be modified as needed when carrying out the present invention, provided that the modifications do not deviate from the scope of the invention.

Claims

[1] A wafer processing method for processing a wafer (11) provided on one side of a front surface (11a) with a component region (17a) in which a component (15) is formed in each of a plurality of regions divided by a plurality of streets (13) arranged in a lattice pattern so as to intersect each other, which wafer is provided on one side of a rear surface (11b) with a recess (19) formed in a region corresponding to the component region (17a), and which wafer is provided at a peripheral portion with an annular reinforcing portion (21) surrounding the component region (17a) and the recess (19), the wafer processing method comprising: a tape attaching step of attaching a pressure-sensitive adhesive tape (23) to the rear surface (11b) side of the wafer (11) along the recess (19) and the reinforcing portion (21); a holding step of holding a bottom surface (19a) of the recess (19) by a first chuck table (4) through the pressure-sensitive adhesive tape (23); a cutting step of cutting the wafer (11) along the streets (13) by a cutting blade (16) to thereby divide the component region (17a) into a plurality of component chips (27) and to form cutting grooves (11c) in the reinforcement portion (21); a dividing step of applying an external force to the reinforcing portion (21) to thereby divide the reinforcing portion (21) with the cutting grooves (11c) as starting points; and a removal step of ejecting fluid toward the reinforcement portion (21) from a predetermined ejection position positioned on an outer side of the wafer (11), thereby dispersing the divided reinforcement portion (21) toward a side opposite to the ejection position and removing the divided reinforcement portion (21). [2] The wafer processing method according to claim 1, wherein in the removing step, the fluid is ejected along a tangential direction of a peripheral edge of the wafer (11). [3] The processing method according to claim 1 or 2, wherein in the dividing step, in a state where the wafer (11) is supported by a second chuck table (32) having projections and recesses (19) at a position corresponding to the reinforcing portion (21) of the wafer (11), the pressure-sensitive adhesive tape (23) is sucked by the second chuck table (32) to thereby arrange the pressure-sensitive adhesive tape (23) along the projections and recesses (19) and divide the reinforcing portion (21). [4] A wafer processing method according to any preceding claim, wherein in the removing step, in a state where a nozzle and a catching mechanism are arranged so that the reinforcement portion (21) of the wafer (11) is sandwiched therebetween, the fluid is ejected from the nozzle to the reinforcement portion (21) to thereby distribute the divided reinforcement portion (21) to the catching mechanism and to catch the divided reinforcement portion (21) by the catching mechanism.

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