TWI902992B - Wafer fabrication methods - Google Patents

Abstract

[Problem] To provide a wafer processing method for easily removing reinforcing portions remaining on the outer periphery of a wafer. [Solution] A wafer processing method for processing a wafer having device regions on its front side, recesses formed in regions corresponding to the device regions on its back side, and annular reinforcing portions surrounding the device regions and the recesses on its outer periphery. The device regions are formed in a plurality of regions divided by a plurality of predetermined dividing lines arranged in a lattice pattern. The aforementioned wafer fabrication method for the device region includes the following steps: a cutting step, dividing the device region into a plurality of device wafers and forming cutting grooves in the reinforcing portion; a slitting step, dividing the reinforcing portion starting from the cutting grooves; and a removal step, removing the slidated reinforcing portion by jetting a fluid from a predetermined jetting position located on the outer side of the wafer toward the reinforcing portion, causing the fluid to scatter toward the side opposite to the jetting position.

Description

Wafer fabrication methods

This invention relates to a method for processing wafers.

In the manufacturing process of device chips, a wafer with device regions on the front side is used. These device regions are areas where devices are formed within a plurality of regions defined by a plurality of dicing lines (cut tracks) arranged in a grid pattern. By dicing this wafer along the dicing lines, a plurality of device chips, each equipped with a device, can be obtained. These device chips can be integrated into various electronic devices such as mobile phones and personal computers.

In recent years, with the miniaturization of electronic devices, there has been an increasing demand for thinner chip designs. Consequently, a method has emerged to thin the wafer before dicing. This wafer thinning process utilizes a grinding apparatus equipped with a worktable and a grinding unit. The worktable holds the workpiece, and the grinding unit is equipped with grinding wheels containing multiple grinding stones. By holding the wafer in the worktable and rotating both the worktable and the grinding wheels while simultaneously bringing the grinding stones into contact with the back side of the wafer, the wafer can be ground and thinned.

If a wafer is ground and thinned, its rigidity decreases, and it becomes more susceptible to breakage during post-grinding handling (transfer, etc.). Therefore, a method has been proposed that involves thinning only the back side of the wafer where the device area overlaps (see Patent 1). Using this method, the central portion of the wafer is thinned to form a recess, while the outer periphery remains thicker, acting as a ring-shaped reinforcement. This helps to suppress the decrease in wafer rigidity after grinding.

Thinned wafers can be diced into multiple device chips using a cutting device that cuts the workpiece with a ring-shaped cutting blade. At this point, the wafer is cut along a predetermined dicing line after removing the remaining ring-shaped reinforcement on its outer periphery. For example, Patent 2 discloses a method where the device area is separated from the reinforcement (ring-shaped protrusion) by circumferentially cutting the outer periphery of the wafer with a cutting blade, and then the reinforcement is lifted and removed by a claw assembly with multiple claws. (Prior Art Documents, Patent Documents)

Patent Document 1: Japanese Patent Application Publication No. 2007-19379 Patent Document 2: Japanese Patent Application Publication No. 2011-61137

The problem this invention aims to solve is as described above: the annular reinforcement remaining on the outer periphery of the wafer is separated and removed during the wafer fabrication process. However, immediately after separation, the reinforcement is positioned close to the device area, enclosing the center of the thinned and weakened wafer (the device area). Therefore, there is a concern that during reinforcement removal, the annular reinforcement may accidentally contact the device area, causing damage.

Therefore, in order to properly remove the reinforcement, the following operations become necessary: carefully holding the reinforcement in a way that prevents it from interfering with the device area, and lifting the reinforcement in a way that does not cause it to wobble or misalign. As a result, the structure of the mechanism used for removing the reinforcement (such as a claw assembly) becomes more complex and the cost increases. Furthermore, the operation time required for removing the reinforcement becomes longer, and the operation efficiency decreases.

This invention is made in view of the aforementioned problems, and its purpose is to provide a wafer processing method that allows for the easy removal of reinforcing portions remaining on the outer periphery of the wafer. Means for solving the problems.

According to one aspect of the present invention, a wafer processing method is provided. The wafer has a device region on its front side, a recess formed on its back side corresponding to the device region, and an annular reinforcement surrounding the device region and the recess on its outer periphery. The device region is a region in which a device is formed in each of a plurality of regions divided by a plurality of predetermined dividing lines arranged in a lattice pattern. The wafer processing method includes the following steps: an adhesive tape application step, whereby adhesive tape is applied along the recess and the recess on the back side of the wafer. The reinforcement is attached with adhesive tape; a holding step is performed by holding the bottom surface of the recess across the adhesive tape using a first work chuck; a cutting step is performed by cutting the wafer along the predetermined dividing line with a cutting blade to divide the device region into a plurality of device chips and forming a cutting groove in the reinforcement; a dividing step is performed by applying external force to the reinforcement and dividing the reinforcement starting from the cutting groove; and a removal step is performed by jetting a jet of fluid from a predetermined jetting position located on the outer side of the wafer toward the reinforcement, causing the divided reinforcement to scatter toward the side opposite to the jetting position to remove it.

Furthermore, preferably, in the removal step, the fluid is sprayed along the tangential direction of the outer periphery of the wafer. Also preferably, in the dicing step, with the wafer already supported by a second working stage having irregularities at a position corresponding to the reinforcement of the wafer, the adhesive tape is attracted by the second working stage, thereby causing the adhesive tape to dice the reinforcement along the irregularity. Furthermore, preferably, in this removal step, the fluid is sprayed from the nozzle toward the reinforcement while the nozzle and the recovery mechanism are configured to clamp the reinforcement of the wafer, thereby causing the slit reinforcement to disperse toward the recovery mechanism for recovery. Invention Effects

In one wafer fabrication method of the present invention, the device region is divided into a plurality of device wafers in a cutting step, and cutting grooves are formed in the reinforcing portion. Furthermore, in the dicing step, an external force is applied to the reinforcing portion, and the reinforcing portion is diced starting from the cutting grooves. This allows the reinforcing portion to be easily removed from the wafer by a simple method of jetting fluid onto the diced reinforcing portion.

Furthermore, in the wafer processing method of this invention, by spraying a fluid from a predetermined spray position located on the outer side of the wafer toward the reinforcing part, the segmented reinforcing part (multiple fragments) is scattered in the opposite direction to the spray position. This prevents fragments from scattering from the wafer in random directions and makes fragment recovery easier.

The following describes one embodiment of the invention with reference to the accompanying drawings. First, an example of the structure of a wafer processed by the wafer processing method of the present embodiment will be described. FIG1(A) is a perspective view showing the front side of wafer 11, and FIG1(B) is a perspective view showing the back side of wafer 11.

The wafer 11 is a disk-shaped substrate made of semiconductors such as silicon, and has a front side 11a and a back side 11b that are generally parallel to each other. The wafer 11 is divided into a plurality of rectangular regions by a plurality of dicing lines (cut tracks) 13 arranged in a lattice pattern in an intersecting manner. Furthermore, on the front side 11a of the wafer 11, in the regions divided by the dicing lines 13, devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integrations), LEDs (Light Emitting Diodes), and MEMSs (Micro Electro Mechanical Systems) are formed.

The wafer 11 has a generally circular device region 17a on the front side 11a, on which a plurality of devices 15 are formed, and an annular peripheral residual region 17b surrounding the device region 17a. The peripheral residual region 17b corresponds to an annular region of the front side 11a with a predetermined width (e.g., about 2 mm) including the outer perimeter. In Figure 1(A), the boundary between the device region 17a and the peripheral residual region 17b is represented by a two-point chain.

Furthermore, there are no restrictions on the material, shape, structure, or size of wafer 11. For example, wafer 11 can also be a substrate made of semiconductors other than silicon (such as gallium arsenide (GaAs), indium phosphide (InP), gallium nitride (GaN), silicon carbide (SiC), etc.), glass, ceramics, resins, metals, etc. Also, there are no restrictions on the type, number, shape, structure, size, or arrangement of devices 15.

By dividing the wafer 11 into a grid shape along the predetermined dividing line 13, a plurality of device chips, each equipped with a device 15, can be manufactured. Furthermore, by performing a thinning process on the wafer 11 before dicing, thinned device chips can be obtained.

In the thinning of wafer 11, a grinding apparatus can be used, for example. The grinding apparatus includes a work chuck (holding stage) for holding wafer 11 and a grinding unit for grinding wafer 11. The grinding unit is equipped with an annular grinding wheel, which includes a plurality of grinding stones. By holding wafer 11 with the work chuck and rotating the work chuck and the grinding wheel respectively while the grinding stones contact the back side 11b of wafer 11, the back side 11b of wafer 11 can be ground, thereby thinning wafer 11.

Furthermore, if the entire back side 11b of wafer 11 is ground, the wafer 11 as a whole will be thinned, which will reduce the rigidity of wafer 11, and wafer 11 will become more easily damaged during handling (transfer, etc.) after grinding. Therefore, there is a practice of only performing thinning treatment (grinding) on the central part of the back side 11b of wafer 11.

For example, as shown in Figure 1(B), only the central portion of wafer 11 is ground and thinned. As a result, a circular recess (groove) 19 can be formed on the back side 11b of wafer 11. Furthermore, the recess 19 is located at a position corresponding to device region 17a. For example, the size (diameter) of the recess 19 is set to be approximately the same as the size (diameter) of device region 17a, and the recess 19 is formed to overlap with a plurality of devices 15.

The recess 19 includes a bottom surface 19a that is generally parallel to the front side 11a and back side 11b of the wafer 11, and an annular side surface (inner wall) 19b that is generally perpendicular to the bottom surface 19a and connects the bottom surface 19a and the back side 11b. Furthermore, an annular reinforcing portion (protrusion) 21 remains on the outer periphery of the wafer 11, corresponding to an area that has not undergone thinning (grinding). The reinforcing portion 21 includes a peripheral remaining area 17b and surrounds the device area 17a and the recess 19.

If only the central portion of wafer 11 is thinned, the outer periphery (reinforcing portion 21) of wafer 11 will remain thicker. This helps to suppress the reduction in rigidity of wafer 11 and makes it less prone to breakage. In other words, the reinforcing portion 21 functions as a reinforcing region of wafer 11.

Next, a specific example of a processing method for dividing the aforementioned wafer 11 into a plurality of device chips will be described. In this embodiment, firstly, adhesive tape is applied to the back side 11b of the wafer 11 (tape application step). Figure 2(A) is a perspective view showing the wafer 11 with adhesive tape 23 applied, and Figure 2(B) is a cross-sectional view showing the wafer 11 with adhesive tape 23 applied.

An adhesive tape 23 of a size that can cover the entire back side 11b of the wafer 11 can be attached to the back side 11b of the wafer 11. For example, a circular adhesive tape 23 with a diameter larger than the wafer 11 can be attached to cover the back side 11b of the wafer 11.

A soft film comprising a circular substrate and an adhesive layer (paste layer) disposed on the substrate can be used as the adhesive tape 23. For example, the substrate is composed of resins such as polyolefins, polyvinyl chloride, and polyethylene terephthalate, and the adhesive layer is composed of epoxy, acrylic, or rubber adhesives. Alternatively, a UV-curing resin that cures upon exposure to ultraviolet light can be used as the adhesive layer.

The adhesive tape 23 is attached along the contour of the back side 11b of the wafer 11. That is, as shown in FIG2(B), the adhesive tape 23 is attached along (conforming to) the bottom surface 19a and side surface 19b of the recess 19 and the back side (lower surface) of the reinforcement 21. Furthermore, although FIG2(B) shows an example in which the adhesive tape 23 is attached to the bottom surface 19a and side surface 19b in close fit, there may also be slight gaps between the adhesive tape 23 and the outer periphery of the bottom surface 19a or between the adhesive tape 23 and the side surface 19b.

An annular frame 25 made of metal such as SUS (stainless steel) is attached to the outer periphery of the adhesive tape 23. A circular opening 25a for accommodating the wafer 11 is provided in the center of the frame 25. The wafer 11 is disposed inside the opening 25a and supported by the frame 25 through the adhesive tape 23. In this way, a frame unit (workpiece assembly) integrating the wafer 11, adhesive tape 23, and frame 25 can be formed.

The wafer 11, to which adhesive tape 23 is attached, is cut by a cutting device. Figure 3 is a perspective view of the cutting device 2. In Figure 3, the X-axis (machining feed direction, first horizontal direction) and the Y-axis (indexing feed direction, second horizontal direction) are perpendicular to each other. Furthermore, the Z-axis (vertical direction, vertical direction, height direction) is perpendicular to both the X-axis and Y-axis. The cutting device 2 includes a worktable (holding table) 4 for holding the wafer 11 and a cutting unit 12 for cutting the wafer 11 held by the worktable 4.

The upper surface of the worktable 4 is formed as a flat surface that is substantially parallel to the X-axis and Y-axis directions, and has a circular holding surface 4a for holding the wafer 11 (see Figure 4). Furthermore, the worktable 4 is connected to a moving mechanism (not shown) and a rotary drive source (not shown). The moving mechanism is a ball screw type mechanism that moves the worktable 4 along the X-axis direction, and the rotary drive source is a drive source such as a motor that rotates the worktable 4 around a rotation axis that is substantially parallel to the Z-axis direction.

A cutting unit 12 for cutting wafers 11 is disposed above the worktable 4. The cutting unit 12 has a hollow cylindrical housing 14, in which a cylindrical spindle (not shown) arranged along the Y-axis is housed. The front end (one end) of the spindle protrudes outside the housing 14, and a rotary drive source such as a motor (not shown) is connected to the base end (the other end) of the spindle.

A ring-shaped cutting insert 16 can be installed at the front end of the spindle. The cutting insert 16 rotates about a rotation axis that is generally parallel to the Y-axis by means of power transmitted from the rotation drive source through the spindle.

For example, hub-type cutting inserts (hub-type inserts) can be used as cutting inserts 16. Hub-type inserts are constructed by integrating a ring-shaped base made of metal or the like with a ring-shaped cutting edge formed along the outer periphery of the base. The cutting edge of the hub-type insert is made of an electroformed grinding stone, which is formed by fixing abrasive grains made of diamond or the like with a bonding material such as nickel plating. Alternatively, washer-type cutting inserts (washer-type inserts) can also be used as cutting inserts 16. Washer-type inserts are constructed by using a ring-shaped cutting edge, which is formed by fixing abrasive grains made of diamond or the like with a bonding material such as metal, ceramic, or resin.

The cutting insert 16, which is mounted on the front end of the spindle, is covered by the insert cover 18 fixed to the housing 14. The insert cover 18 has a connection portion 20 for connecting to a pipe (not shown) for supplying a liquid (cutting fluid) such as pure water, and a pair of nozzles 22 connected to the connection portion 20 and respectively disposed on both sides (front side and back side) of the cutting insert 16. Each of the pair of nozzles 22 has a spray port (not shown) that opens toward the cutting insert 16.

When the wafer 11 is cut by the cutting blade 16, cutting fluid is supplied to the connection part 20 and sprayed from the nozzles of a pair of nozzles 22 toward both sides (front and back) of the cutting blade 16. In this way, the wafer 11 and the cutting blade 16 are cooled, and the chips (cutting chips) generated by the cutting process are washed away.

A ball screw type moving mechanism (not shown) is connected to the cutting unit 12 to move the cutting unit 12. This moving mechanism moves the cutting unit 12 along the Y-axis and raises and lowers it along the Z-axis.

When cutting wafer 11, wafer 11 is first held by work clamp 4 (first work clamp) (holding step). Figure 4 is a cross-sectional view showing wafer 11 held by work clamp 4.

The worktable 4 has a cylindrical frame (body) 6 made of metal, glass, ceramic, resin, etc. A circular recess (groove) 6b is formed on the upper surface 6a of the frame 6, and a disc-shaped retaining member 8 is embedded in the recess 6b. The retaining member 8 is a member formed of a porous material such as porous ceramic, and contains a hole (suction path) connecting the upper surface of the retaining member 8 to the lower surface.

The upper surface 6a of the frame 6 and the upper surface 8a of the retaining member 8 are arranged on approximately the same plane, forming the retaining surface 4a of the work clamp 4. Furthermore, the upper surface 8a of the retaining member 8 forms a circular attracting surface that attracts the wafer 11. The retaining surface 4a is connected to an attracting source (not shown) such as an ejector through flow paths (not shown) and valves (not shown) formed inside the retaining member 8 and the frame 6.

The wafer 11 is positioned on the work fixture 4 with its front side 11a facing upwards. Furthermore, the work fixture 4 is configured such that the bottom surface 19a of the recess 19 of the wafer 11 can be held by a holding surface 4a. Specifically, the diameter of the holding surface 4a is smaller than the diameter of the recess 19, allowing the holding surface 4a of the work fixture 4 to be inserted into the recess 19. In this way, the bottom surface 19a of the recess 19 can be supported by the holding surface 4a through the adhesive tape 23.

Furthermore, a plurality of clamps 10 are provided around the worktable 4 to hold and fix the frame 25. After the wafer 11 is placed on the worktable 4, the frame 25 can be fixed by the plurality of clamps 10.

If, with the wafer 11 already positioned on the work fixture 4, the attractive force (negative pressure) of the attraction source is applied to the holding surface 4a, the area of the adhesive tape 23 attached to the bottom surface 19a of the recess 19 will be attracted by the holding surface 4a. In this way, the bottom surface 19a of the recess 19 will be attracted and held by the work fixture 4 through the adhesive tape 23.

Next, the wafer 11 is cut by the cutting blade 16 along the dicing predetermined line 13 (see FIG3, etc.) (cutting step). In the cutting step, the wafer 11 is cut along the dicing predetermined line 13 which is parallel to the first direction and the dicing predetermined line 13 which is parallel to the second direction which intersects the first direction.

Figure 5(A) is a cross-sectional view showing the wafer 11 being cut along the first direction. First, the worktable 4 is rotated, and the length direction of a dicing predetermined line 13 parallel to the first direction is aligned with the X-axis direction. Then, the position of the cutting unit 12 in the Y-axis direction is adjusted such that the cutting blade 16 is positioned on the extension of the dicing predetermined line 13.

Furthermore, the height of the cutting unit 12 is adjusted such that the lower end of the cutting blade 16 is positioned below the bottom surface 19a of the recess 19. For example, the lower end of the cutting blade 16 can be positioned below the upper surface of the adhesive tape 23 attached to the bottom surface 19a of the recess 19, and above the holding surface 4a (the lower surface of the adhesive tape 23). At this time, the height difference between the front surface 11a of the wafer 11 and the lower end of the cutting blade 16 is equivalent to the cutting depth of the cutting blade 16 into the wafer 11.

Furthermore, while rotating the cutting blade 16, the worktable 4 is moved along the X-axis. In this way, the worktable 4 and the cutting blade 16 move relative to each other along the X-axis (machining feed), and the cutting blade 16 cuts into the front side 11a of the wafer 11 along a predetermined dividing line 13.

At this time, the cutting depth of the cutting blade 16 is greater than the thickness of the central portion (device region 17a) of the wafer 11, and less than the thickness of the outer periphery (reinforcing portion 21) of the wafer 11. Therefore, a cut (blade mark) from the front surface 11a to the bottom surface 19a can be formed in the device region 17a of the wafer 11 along a predetermined dicing line 13. On the other hand, a cutting groove 11c with a depth corresponding to the cutting depth of the cutting blade 16 can be formed in the reinforcing portion 21 of the wafer 11 along a predetermined dicing line 13.

Then, the cutting blade 16 is moved in the Y-axis direction by the interval of the dicing pre-line 13 (indexing feed) to cut the wafer 11 along the other dicing pre-line 13. By repeating this process, the wafer 11 can be cut along all the dicing pre-line 13 parallel to the first direction.

Next, the worktable 4 is rotated 90° to align the length direction of the dicing predetermined line 13, which is parallel to the second direction, with the X-axis. Then, the wafer 11 is cut along all the dicing predetermined lines 13, which are parallel to the second direction, by the same process. Figure 5(B) is a cross-sectional view showing the wafer 11 being cut along the second direction.

After the wafer 11 is cut along all the dicing lines 13, the device region 17a of the wafer 11 is divided along the dicing lines 13, resulting in a plurality of device wafers 27, each equipped with a device 15 (see FIG. 6). Furthermore, cutting grooves 11c are formed along the dicing lines 13 on the upper surface (front side) of the reinforcement 21.

Next, the reinforcing part 21 is divided by applying external force to the reinforcing part 21, starting from the cutting groove 11c (division step). In this embodiment, the reinforcing part 21 is subjected to external force by attracting the adhesive tape 23 with the second work table.

Figure 6 is a perspective view showing the external force application unit 30. The external force application unit 30 is a mechanism for applying external force to the wafer 11 and can be installed inside or outside the cutting device 2 (see Figure 3). The external force application unit 30 has a work clamp (holding stage) 32 for holding the wafer 11.

The upper surface of the work stage 32 is a circular holding surface that holds the wafer 11. Furthermore, a rotary drive source (not shown), such as a motor, is connected to the work stage 32, which causes the work stage 32 to rotate about a rotation axis that is substantially parallel to the vertical direction.

The worktable 32 has a cylindrical frame (body) 34 made of metal, glass, ceramic, resin, etc. A circular recess (groove) 34b is formed in the center of the upper surface 34a of the frame 34, and a disc-shaped retaining member 36 is embedded in the recess 34b. The retaining member 36 is a member formed of a porous material such as porous ceramic, and contains a hole (suction path) connecting the upper surface of the retaining member 36 to the lower surface.

The upper surface of the retaining component 36 is configured with a circular attraction surface 36a that attracts and retains the wafer 11. The attraction surface 36a is disposed on a plane that is substantially the same as the upper surface 34a of the frame 34.

The worktable 32 has protrusions and recesses at positions corresponding to the reinforcement 21 of the wafer 11. For example, the frame 34 is formed such that its upper surface 34a overlaps with the reinforcement 21 when the wafer 11 is placed on the worktable 32. Furthermore, a plurality of protrusions (bulges) 38 protruding upward from the upper surface 34a are provided on the side of the upper surface 34a of the frame 34. Moreover, although the protrusions 38 are shown in the shape of cuboids in FIG. 6, there is no limitation on the shape of the protrusions 38.

A plurality of protrusions 38 are arranged at approximately equal intervals along the circumference of the frame 34. Furthermore, the upper surface 34a of the frame 34 and the protrusions 38 can form a periodic concave-convex annular region.

Furthermore, annular grooves 40a and 40b with openings in the upper surface 34a are provided on the side of the frame 34. For example, the grooves 40a and 40b are formed concentrically on both sides of the plurality of protrusions 38 (the outer and inner sides in the radial direction of the frame 34). Moreover, the grooves 40a and 40b are connected to each other by a plurality of grooves 40c formed along the radial direction of the frame 34.

The retaining component 36 is connected to the suction source 44 via a flow path (not shown) disposed inside the frame 34 and a valve 42a. Similarly, channels 40a, 40b, and 40c are connected to the suction source 44 via a flow path (not shown) disposed inside the frame 34 and a valve 42b. The suction source 44 can be, for example, an injector.

The wafer 11 is disposed on the work stand 32 with the reinforcing part 21 and the upper surface 34a of the frame 34 overlapping. In this way, the reinforcing part 21 of the wafer 11 is supported by a plurality of protrusions 38 through the adhesive tape 23.

Figure 7(A) is a cross-sectional view showing the wafer 11 disposed on the work clamp 32. Furthermore, for ease of explanation, only the cross-sectional shape of the wafer 11, adhesive tape 23, frame 25, and work clamp 32 is shown in Figure 7(A). If valves 42a and 42b are opened while the wafer 11 is disposed on the work clamp 32, the attractive force (negative pressure) of the attraction source 44 will act on the attraction surface 36a and grooves 40a, 40b, and 40c, and the wafer 11 can be attracted and held by the work clamp 32 through the adhesive tape 23.

Figure 7(B) is a cross-sectional view showing the wafer 11 attracted by the work stage 32. The areas of the adhesive tape 23 attached to the plurality of device chips 27 are attracted and come into contact with the attraction surface 36a. Also, the areas of the adhesive tape 23 attached to the back side 11b of the outer periphery (reinforcement 21) of the wafer 11 and the areas nearby thereon are attracted by the grooves 40a, 40b and come into contact with the upper surface 34a of the frame 34.

Here, as shown in Figure 6, a periodic undulation is formed in a ring shape on the upper surface 34a side of the frame 34 by a plurality of protrusions 38. Therefore, when negative pressure is applied to the grooves 40a and 40b, the area of the adhesive tape 23 attached to the outer periphery of the wafer 11 will deform and become undulating along the upper surface 34a of the frame 34 and the protrusions 38. Furthermore, the areas of the reinforcement 21 not supported by the protrusions 38 will be stretched by the adhesive tape 23 toward the upper surface 34a side of the frame 34 and moved into the space between adjacent protrusions 38. As a result, shear stress will act on the reinforcement 21. That is, the reinforcement 21 can be subjected to external force by attracting the adhesive tape 23 with the work clamp 32.

If an external force is applied to the reinforcing part 21, cracks will form from the cutting groove 11c formed in the reinforcing part 21 and will develop in the thickness direction of the reinforcing part 21. As a result, the reinforcing part 21 will break along the predetermined dividing line 13. That is, the cutting groove 11c functions as the starting point for the division of the reinforcing part 21, and the annular reinforcing part 21 is divided into a plurality of fragments along the predetermined dividing line 13.

Figure 8 is a perspective view of a wafer 11 in which the reinforcement 21 has been divided into a plurality of fragments 29. As shown in Figure 8, among the plurality of fragments 29 formed by the division of the reinforcement 21, the fragment 29 supported by the protrusion 38 of the work chuck 32 (see Figure 6, etc.) is configured to protrude upwards more than the other fragments 29 and the device wafer 27.

Furthermore, in the segmentation step, it is not necessary to segment the reinforcement 21 along the entire cutting groove 11c. Specifically, it is sufficient to segment the reinforcement 21 into a plurality of fragments of a predetermined size or less so that the reinforcement 21 can be properly removed in the removal step described later.

Furthermore, although Figure 6 illustrates an example of forming the concave and convex surfaces of the work clamp 32 using the upper surface 34a of the frame 34 and the protrusions 38, there are no limitations on the method of forming the concave and convex surfaces. For example, the concave and convex surfaces can also be formed by providing a plurality of recesses (grooves) on the upper surface 34a side of the frame 34.

Furthermore, the method of applying external force to the reinforcing part 21 is not limited to the attraction of the adhesive tape 23 by the work clamp 32. For example, the pressing component can be pressed onto the reinforcing part 21 while the wafer 11 is held by a predetermined work clamp, thereby applying external force to the reinforcing part 21. Alternatively, an adhesive tape that can expand with the application of external force (expansion tape) can be used as the adhesive tape 23, and external force can be applied to the reinforcing part 21 by stretching and expanding the expansion tape.

Next, the reinforcing portion 21, which has been divided into a plurality of fragments 29, is removed (removal step). In the removal step, each fragment 29 formed by the division of the reinforcing portion 21 is peeled off from the adhesive tape 23.

Figure 9 is a perspective view showing the wafer 11 in the removal step. For example, a nozzle 46 for jetting fluid 48 and a recovery mechanism 50 for recovering reinforcement 21 (fragment 29) can be provided around the wafer 11 held by the work stage 32 (see Figure 6, etc.).

The nozzle 46 is fixed at a predetermined spraying position located further outward in the radial direction from the outer edge of the wafer 11 than the outer periphery of the wafer 11. A fluid supply source (not shown) for supplying fluid 48 to the nozzle 46 is connected to the nozzle 46. The nozzle 46 also has a spray port 46a, which sprays the fluid 48 supplied from the fluid supply source. Furthermore, there are no restrictions on the fluid 48 that can be sprayed from the nozzle 46; a gas such as air can be used. Alternatively, a pressurized liquid such as pure water (high-pressure liquid) or a mixture of liquid (pure water, etc.) and gas (air, etc.) can also be used as the fluid 48.

For example, the nozzle 46 is positioned at approximately the same height as the wafer 11, with the spray port 46a facing the outer periphery (reinforcing portion 21). Furthermore, the direction of the nozzle 46 can be adjusted so that the spray port 46a intersects the tangent of the outer periphery of the wafer 11. This allows the fluid 48 to be sprayed along the tangential direction of the outer periphery of the wafer 11.

As the recycling mechanism 50, a container with an opening 50a can be used, which faces the nozzle 46a of the nozzle 46. Furthermore, the nozzle 46 and the recycling mechanism 50 are configured to sandwich the reinforcing portion 21 of the wafer 11. For example, the nozzle 46 and the recycling mechanism 50 can be positioned on the tangent of the outer periphery of the wafer 11. Thereby, the reinforcing portion 21 is disposed between the nozzle 46a and the opening 50a of the recycling mechanism 50.

In the removal step, a work stand 32 (see Figure 6, etc.) holding the wafer 11 is rotated at a low speed (e.g., 5-10 rpm) while jetting fluid 48 from nozzle 46. This allows the fluid 48 to be jetted from a jetting position (the position of nozzle 46) located outside the wafer 11 toward the reinforcement 21. As a result, the fluid 48 applies pressure to the reinforcement 21, causing the separated reinforcement 21 (fragments 29) to peel off from the adhesive tape 23. Furthermore, the separated reinforcement 21 (fragments 29) disperses in the opposite direction to the jetting position of the fluid 48.

If the wafer 11 rotates once while it has been sprayed with fluid 48 from the nozzle 46, fluid 48 can be sprayed over the entire area of the reinforcement 21, thereby peeling all the debris 29 off the adhesive tape 23. In this way, the reinforcement 21 can be removed, leaving only a plurality of device chips 27 on the adhesive tape 23.

Thus, in this embodiment, since the annular reinforcement 21 is divided into a plurality of fragments 29 in the segmentation step, the reinforcement 21 can be easily removed in the removal step by simply applying an appropriate external force to each fragment 29. This eliminates the need for the preparation or operation of a sophisticated conveying mechanism for transporting the annular reinforcement 21, thereby simplifying the removal operation of the reinforcement 21.

Furthermore, as shown in Figure 9, if the jetting position of the fluid 48 (the position of the nozzle 46) is set on the outer side of the wafer 11, the fragment 29 will scatter from the wafer 11 in a single direction. This prevents the fragment 29 from scattering in any direction from the wafer 11 and makes the recovery of the fragment 29 easier.

Furthermore, by configuring the recycling mechanism 50 to face the nozzle 46, the fragments 29 scattered by the jet of the fluid 48 can be guided to the opening 50a of the recycling mechanism 50 and enter the recycling mechanism 50. That is, the recycling and removal of fragments 29 can be carried out simultaneously. As a result, it is no longer necessary to collect the scattered fragments 29 after the removal step, thus improving work efficiency.

Furthermore, there are no restrictions on the type of recycling mechanism 50. For example, the recycling mechanism 50 can also be a conduit connected to an attraction source such as a jet. In this case, the scattered fragments 29 can be reliably guided to the conduit by jetting fluid 48 from the nozzle 46 and by applying the attraction force (negative pressure) of the attraction source to the conduit.

As described above, in the wafer fabrication method of this embodiment, the device region 17a is divided into a plurality of device wafers 27 in the cutting step, and cutting grooves 11c are formed in the reinforcing portion 21. Then, in the dicing step, an external force is applied to the reinforcing portion 21, and the reinforcing portion 21 is diced starting from the cutting grooves 11c. In this way, the reinforcing portion 21 can be easily removed from the wafer 11 by a simple method of spraying fluid 48 onto the diced reinforcing portion 21.

Furthermore, in the wafer processing method of this embodiment, by spraying the jet 48 from a predetermined spray position located on the outer side of the wafer 11 toward the reinforcement 21, the segmented reinforcement 21 (a plurality of fragments 29) are scattered in the opposite direction to the spray position. This prevents the fragments 29 from scattering from the wafer 11 in any direction and makes the recovery of the fragments 29 easier.

Furthermore, in the removal step, the reinforcement 21 can also be removed by alternately performing the spraying of fluid 48 and the rotation of the work clamp 32. Specifically, firstly, with the work clamp 32 stopped, a portion of the reinforcement 21 is sprayed with fluid 48. Then, the work clamp 32 is rotated by a predetermined angle, and fluid 48 is sprayed onto a portion of the reinforcement 21 again. This operation can be repeated until the wafer 11 rotates one revolution to remove all the debris 29 from the adhesive tape 23.

Furthermore, during the removal process, multiple device chips 27 can also be coated with a protective film. For example, pure water can be supplied from above the worktable 32 toward the wafer 11 to cover the multiple device chips 27 with a water film. In this way, in the event that fragments 29 fly toward the device chips 27, it will become difficult to damage the device chips 27.

Furthermore, although this embodiment illustrates an example of using the same work clamp 32 (see FIG6, etc.) to perform the dicing and removal steps, it is also possible to hold the wafer 11 using different work clamps in the dicing and removal steps.

Furthermore, the structure and methods of the above-mentioned embodiments can be appropriately modified and implemented as long as they do not depart from the purpose of this invention.

2: Cutting device 4,32: Work chuck (holding table) 4a: Holding surface 6,34: Frame (body) 6a,8a,34a: Upper surface 6b,19,34b: Recess (groove) 8,36: Holding component 10: Fixture 11: Wafer 11a: Front side 11b: Back side 11c: Cutting groove 12: Cutting unit 13: Dividing pre-line (cutting track) 14: Housing 15: Device 16: Cutting blade 17a: Device area 17b: Outer peripheral remaining area 1 8: Blade cover 19a: Bottom surface 19b: Side (inner wall) 20: Connecting part 21: Reinforcing part (protrusion) 22, 46: Nozzle 23: Adhesive tape 25: Frame 25a: Opening 27: Device chip 29: Fragment 30: External force application unit 36a: Suction surface 38: Protrusion (bulge) 40a, 40b, 40c: Groove 42a, 42b: Valve 44: Suction source 46a: Spray port 48: Fluid 50: Recovery mechanism 50a: Opening X, Y, Z: Direction

Figure 1(A) is a perspective view showing the front side of the wafer, and Figure 1(B) is a perspective view showing the back side of the wafer. Figure 2(A) is a perspective view showing the wafer with adhesive tape attached, and Figure 2(B) is a cross-sectional view showing the wafer with adhesive tape attached. Figure 3 is a perspective view showing the cutting device. Figure 4 is a cross-sectional view showing the wafer held by the work chuck. Figure 5(A) is a cross-sectional view showing the wafer being cut along the first direction, and Figure 5(B) is a cross-sectional view showing the wafer being cut along the second direction. Figure 6 is a perspective view showing the external force and unit. Figure 7(A) is a cross-sectional view showing the wafer positioned on the work chuck, and Figure 7(B) is a cross-sectional view showing the wafer attracted by the work chuck. Figure 8 is a three-dimensional view showing a wafer whose reinforcement has been divided into multiple fragments. Figure 9 is a three-dimensional view showing a wafer in the removal step.

11: Wafer

11a: Front

11b: Back side

11c: Cutting groove

15: Devices

17a: Device Region

21: Reinforcement part (convex part)

23: Adhesive Tape

25: Framework

25a: Opening

27: Device Chips

29: Fragments

46: Spraying lips

46a: Injection nozzle

48: Fluid

50: Recycling organizations

50a: Opening section

Claims (3)

A wafer processing method involves processing a wafer having a device region on its front side, a recess formed in a region corresponding to the device region on its back side, and an annular reinforcement surrounding the device region and the recess on its outer periphery. The device region is a region in which devices are formed in each of a plurality of regions divided by a plurality of predetermined dividing lines arranged in a lattice pattern. The wafer processing method is characterized by the following steps: an adhesive tape application step, in which adhesive tape is applied along the recess and the reinforcement on the back side of the wafer; and a holding step, using a first work clamp... The platform holds the bottom surface of the recessed portion apart with adhesive tape; the cutting step divides the device region into multiple device chips by cutting the wafer along the predetermined dividing line with a cutting blade, and forming a cutting groove in the reinforcement; the dividing step divides the reinforcement by applying external force to the reinforcement, starting from the cutting groove; and the removal step removes the divided reinforcement by spraying a fluid from a predetermined spraying position on the outer side of the wafer toward the reinforcement, causing the fluid to scatter toward the side opposite to the spraying position. In the removal step, the fluid is sprayed along the tangential direction of the outer periphery of the wafer. A wafer processing method involves processing a wafer having a device region on its front side, a recess formed in a region corresponding to the device region on its back side, and an annular reinforcement surrounding the device region and the recess on its outer periphery. The device region is a region in which devices are formed in each of a plurality of regions divided by a plurality of predetermined dividing lines arranged in a lattice pattern. The wafer processing method is characterized by the following steps: an adhesive tape application step, in which adhesive tape is applied to the back side of the wafer along the recess and the reinforcement; a holding step, in which the bottom surface of the recess is held by a first work chuck through the adhesive tape; and a cutting step, in which the wafer is cut... A cutting blade cuts the wafer along the predetermined dicing line, dividing the device region into a plurality of device wafers and forming cutting grooves in the reinforcement; a dicing step, by applying external force to the reinforcement, divides the reinforcement starting from the cutting grooves; and a removal step, by spraying material from a predetermined spraying position located on the outside of the wafer toward the reinforcement. The fluid is sprayed from the nozzle toward the reinforcement portion, causing the slit reinforcement portion to scatter toward the side opposite to the spraying position for removal. In this removal step, the fluid is sprayed from the nozzle toward the reinforcement portion while the nozzle and the recovery mechanism are configured to clamp the reinforcement portion of the wafer, thereby causing the slit reinforcement portion to scatter toward the recovery mechanism for recovery. As in the wafer processing method of claim 1 or 2, in the dicing step, the wafer is supported by a second work clamp having a concave-convex arrangement at a position corresponding to the reinforcement of the wafer, and the adhesive tape is attracted by the second work clamp, thereby causing the adhesive tape to diced the reinforcement along the concave-convex arrangement.