Wafer processing method

Abstract

To provide a wafer processing method capable of removing a modified layer exposed to a side surface of a chip while reducing loss of a material.SOLUTION: Forming a deteriorated layer inside the wafer along each division line by applying a laser beam having a transmission wavelength to the wafer along each division line while focusing the laser beam inside the wafer; attaching a first tape to the back side of the wafer after performing the deteriorated layer forming step; and forming cracks in the wafer from the deteriorated layer as a start point after performing the first tape attaching step, thereby dividing the wafer into a plurality of chips; The wafer processing method includes a gap forming step of forming a gap between the plurality of chips by expanding the first tape, and a cutting step of cutting side surfaces of the chips by inserting a cutting blade into the gap and causing the cutting blade to cut into the side surfaces of the chips after the gap forming step.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a wafer processing method. [Background technology]

[0002] Semiconductor device chips used in electrical devices such as mobile phones and lighting equipment are manufactured, for example, by dividing a wafer made of a semiconductor. Specifically, for example, planned division lines are set on the front surface of the wafer. Devices such as ICs (Integrated Circuits) and LEDs (Light Emitting Diodes) are formed in the areas of the wafer divided by the planned division lines. The back surface of the wafer with devices formed on its front surface is ground using a grinding device or the like to form it to a predetermined thickness, and then the wafer is divided along the planned division lines using a processing device such as a cutting device equipped with an annular cutting blade. This produces a plurality of semiconductor device chips, each having a device.

[0003] When manufacturing semiconductor device chips equipped with LEDs as devices, wafers made of sapphire, which has excellent properties such as optical transparency, are often used. Sapphire wafers generally have a relatively high hardness. When cutting a wafer made of a hard material such as sapphire using a cutting device, unless a cutting blade with a sufficiently large cutting edge and high mechanical strength is used, the cutting blade may be damaged.

[0004] However, as the thickness of the cutting blade increases, the width of the kerf (cut groove) formed in the wafer also increases, which reduces the area of ​​the wafer that can actually be used as a semiconductor device chip, resulting in increased material waste.

[0005] Therefore, when dividing a wafer along the planned dividing lines, instead of using a cutting device equipped with a cutting blade, it is conceivable to use a laser processing device that irradiates a wafer with a laser beam to laser-process the wafer (see, for example, Patent Document 1). The laser processing device forms an altered layer along the planned dividing lines inside the wafer by irradiating the wafer with a laser beam of a wavelength that transmits the wafer while focusing the laser beam inside the wafer. Then, an external force is applied to the wafer, causing cracks to originate from the altered layer along the planned dividing lines. As a result, the wafer is divided along the planned dividing lines, and multiple semiconductor device chips (LED chips) are formed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-192370 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when using a laser beam to divide a wafer, part of the altered layer formed by the laser beam irradiation remains on the divided LED chips and is exposed on the side of the chip. This altered layer inhibits light emission from the LED, reducing the brightness of the LED. Furthermore, even in devices other than LEDs, the remaining altered layer on the chip can become a starting point for breakage, reducing the strength of the chip.

[0008] Therefore, it is conceivable to remove the deteriorated layer from the formed chips, for example, by applying an external force to the wafer to generate cracks and divide the wafer, and then by using a cutting device to cut a cutting blade into the cracks and the deteriorated layer, thereby removing the deteriorated layer from the wafer.

[0009] However, the width of the crack is extremely narrow, and the cutting blade is subjected to a load essentially the same as when cutting the wafer itself, which raises the risk of the cutting blade breaking. As a result, the wafer must be cut using a thick cutting blade with high mechanical strength, which cuts deeply into areas where the affected layer is not formed, resulting in a problem of significant material loss.

[0010] In view of the above circumstances, an object of the present invention is to provide a wafer processing method that can remove an affected layer exposed on the side surface of a chip while reducing material loss. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is provided a wafer processing method for forming a plurality of chips from a wafer by dividing the wafer along a planned dividing line set on the surface of the wafer, the method comprising: a deteriorated layer forming step of forming a deteriorated layer inside the wafer along the planned dividing line by irradiating a laser beam of a wavelength that passes through the wafer along the planned dividing line while focusing it inside the wafer; a first tape applying step of applying a first tape to the back surface of the wafer after the deteriorated layer forming step; a gap forming step of dividing the wafer into a plurality of chips by forming cracks in the wafer starting from the deteriorated layer and expanding the first tape to form gaps between the plurality of chips; and a cutting step of cutting the side surfaces of the chips by inserting a cutting blade into the gaps and cutting into the side surfaces of the chips after the gap forming step.

[0012] Preferably, in the gap forming step, the crack is formed by pressing the wafer before expanding the first tape.

[0013] Preferably, in the gap forming step, the gap is formed between a first side surface of a first tip and a second side surface of a second tip adjacent to the first tip, the second side surface facing the first side surface, and in the cutting step, the cutting blade has a circular first surface and a circular second surface opposite the first surface, and the first surface side of the cutting blade is caused to cut into the first side surface and the second surface side of the cutting blade is caused to cut into the second side surface, thereby simultaneously cutting the first side surface side of the first tip and the second side surface side of the second tip.

[0014] Preferably, the cutting blade has a stacked structure of a first cutting edge portion having the first surface, a second cutting edge portion having the second surface, and a third cutting edge portion arranged between the first cutting edge and the second cutting edge portion, the third cutting edge portion being more easily worn than the first cutting edge portion, and the third cutting edge portion being more easily worn than the second cutting edge portion, and in the cutting step, the first cutting edge portion cuts the first side surface of the first tip, and the second cutting edge portion cuts the second side surface of the second tip.

[0015] Preferably, the method further includes a second tape adhering step of adhering a second tape to the front surface of the wafer before the deteriorated layer forming step, and a second tape peeling step of peeling off the second tape adhered to the front surface of the wafer after the deteriorated layer forming step and before the cutting step, wherein in the deteriorated layer forming step, the laser beam is irradiated onto the wafer from the back side of the wafer, and in the cutting step, the cutting blade is inserted into the gap from the front side of the wafer. [Effects of the Invention]

[0016] In the wafer processing method according to the present invention, a laser beam is irradiated onto the wafer to form an altered layer, and cracks are formed starting from the altered layer to divide the wafer. In this case, material loss can be reduced compared to when the wafer is divided by cutting the wafer with a cutting blade to form dividing grooves.

[0017] After dividing the wafer to form multiple chips, the first tape attached to the wafer is expanded to form gaps between the chips. A cutting blade is then inserted into the gaps and the sides of the chips are cut with the cutting blade. This allows the affected layer exposed on the side of the chip to be removed. Because no material from the wafer is present in the gaps, no material is lost by inserting the cutting blade into the gaps. Furthermore, even when using a cutting blade, the chips can be cut with the minimum amount necessary to remove the affected layer, again reducing material loss. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view of a wafer. [Figure 2] FIG. 2 is a flowchart of the wafer processing method according to the first embodiment. [Figure 3] FIG. 3 is a perspective view of the mounter device and the wafer in the second tape adhering step. [Figure 4] FIG. 4 is a cross-sectional view of the mounter device and the wafer in the second tape adhering step. [Figure 5] FIG. 5 is a partial cross-sectional side view of the grinding device and the wafer in the grinding step. [Figure 6] FIG. 6 is a perspective view of the laser irradiation device and the wafer in the affected layer forming step. [Figure 7] FIG. 7 is a cross-sectional view of the laser irradiation device and the wafer in the affected layer forming step. [Figure 8] FIG. 8 is a perspective view of the mounter device, the wafer, and the frame in the first tape applying step. [Figure 9] FIG. 9 is a cross-sectional view of the mounter device, the wafer, and the frame in the first tape applying step. [Figure 10] FIG. 10 is a perspective view of the separation device, the wafer, and the frame in the second tape separation step. [Figure 11]FIG. 11 is a cross-sectional view of the separation device, the wafer, and the frame in the second tape separation step. [Figure 12] FIG. 12 is a partial cross-sectional side view of the breaking device, wafer, and frame in the gap forming step. [Figure 13] FIG. 13 is a partial cross-sectional side view of the expansion device, wafer, and frame in the gap forming step. [Figure 14] FIG. 14 is a partial cross-sectional side view of the expansion device, wafer, and frame in the gap forming step. [Figure 15] FIG. 15 is a perspective view of the cutting device and the wafer in the cutting step. [Figure 16] FIG. 16 is a partial cross-sectional side view of the cutting device and the wafer in the cutting step. [Figure 17] FIG. 17 is a cross-sectional view of the wafer and the first tape during the cutting step. [Figure 18] FIG. 18 is a partial cross-sectional side view of the cutting blade, wafer, and first tape during the cutting step. [Figure 19] FIG. 19 is a cross-sectional view of the wafer and the first tape during the cutting step. [Figure 20] FIG. 20 is a partial cross-sectional side view of the cutting blade, wafer, and first tape during the cutting step. [Figure 21] FIG. 21 is a partial cross-sectional side view of a cutting blade, a wafer, and a first tape in a cutting step of the wafer processing method according to the second embodiment. [Figure 22] FIG. 22 is a partial cross-sectional side view of the cutting blade, the wafer, and the first tape in the cutting step of the wafer processing method according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In a wafer processing method according to an embodiment of the present invention, a plurality of chips are formed from a wafer by dividing the wafer along planned dividing lines set on the surface of the wafer. First, the wafer will be described. Figure 1 is a perspective view of a wafer 11.

[0020] The wafer 11 is formed of, for example, silicon (Si), silicon carbide (SiC), gallium nitride (GaN), or other semiconductor materials (GaAs, InP, etc.). Alternatively, the wafer 11 is formed of materials such as sapphire, glass, ceramics, resin, and metal. As shown in FIG. 1, the wafer 11 is configured in a disk shape having a circular first surface (front surface) 11a and a circular second surface (back surface) 11b opposite the first surface 11a. However, the material and shape of the wafer 11 are not limited to these.

[0021] A notch 11c is formed in a part of the outer periphery (peripheral edge) of the wafer 11 to indicate the crystal orientation of the wafer 11. Note that an orientation flat may be formed in the wafer 11 instead of the notch 11c. Furthermore, the wafer 11 may not necessarily have the notch 11c or the orientation flat formed therein.

[0022] In addition, a chamfered portion 11d is formed on the peripheral edge of the first surface 11a of the wafer 11, where the corners of the peripheral edge are removed to form a rounded chamfer, in order to increase the mechanical strength of the wafer 11. However, the wafer 11 does not necessarily have to have the chamfered portion 11d formed thereon.

[0023] The first surface 11a has planned division lines 13 set in a grid pattern. Specifically, the planned division lines 13 include a first group of planned division lines 13a parallel to a first direction (a direction along the A axis in FIG. 1) and a second group of planned division lines 13b parallel to a second direction (a direction along the B axis in FIG. 1) perpendicular to the first direction.

[0024] The first surface 11a is divided into a plurality of regions by the dividing lines 13a and the dividing lines 13b. A device 15 such as an IC (Integrated Circuit) is formed in each of the plurality of regions. However, the dividing lines 13 do not necessarily have to be set on the wafer 11. Also, the device 15 does not necessarily have to be formed on the wafer 11.

[0025] Next, a wafer processing method according to an embodiment of the present invention will be described. FIG. 2 is a flowchart of the wafer processing method according to the first embodiment. As shown in FIG. 2, the wafer processing method according to this embodiment includes a second tape application step S1, a grinding step S2, a deteriorated layer formation step S3, a first tape application step S4, a second tape peeling step S5, a gap formation step S6, and a cutting step S7. The first tape application step S4 and the second tape peeling step S5 are collectively referred to as a tape replacement step S11.

[0026] In the wafer processing method according to the embodiment of the present invention, in the deteriorated layer forming step S3, a laser beam is irradiated onto the wafer 11 to form an deteriorated layer inside the wafer 11. Then, in the first tape applying step S4, a first tape is applied to the second surface 11b of the wafer 11. Then, in the gap forming step S6, cracks are formed in the wafer 11 starting from the deteriorated layer, thereby dividing the wafer 11 into multiple chips. Next, the first tape is expanded to form gaps between the multiple chips. Then, in the cutting step S7, a cutting blade is inserted into the gaps and cuts into the side surfaces of the chips, thereby cutting the side surfaces of the chips.

[0027] Note that a second tape may be attached to the first surface 11a of the wafer 11 before forming an altered layer inside the wafer 11. In this case, after forming an altered layer inside the wafer 11, the second tape attached to the first surface 11a of the wafer 11 is peeled off before a cutting blade is used to cut into the side surfaces of the chips formed by dividing the wafer 11. Each step will be described in detail below.

[0028] In the second tape application step S1, a second tape (backgrind tape) is applied to the wafer 11. The second tape application step S1 is performed by a mounter device that applies the second tape to the wafer 11. FIG. 3 is a perspective view of the mounter device 2a and the wafer 11 in the second tape application step S1, and FIG. 4 is a cross-sectional view of the mounter device 2a and the wafer 11 in the second tape application step S1.

[0029] First, the mounter device 2a will be described. As shown in Fig. 4, the mounter device 2a has a holding table 4a. Note that the holding table 4a is not shown in Fig. 3.

[0030] The holding table 4a includes a disk-shaped frame 6a made of a metal such as stainless steel. A recess 60a with a circular opening at the top end is formed on the upper surface of the frame 6a. A disk-shaped holding plate 8a that matches the shape of the recess 60a is fitted into the recess 60a. The holding plate 8a is a plate-shaped porous member made of a material such as ceramics. The holding table 4a holds a wafer 11 placed on the upper surface (holding surface) 80a of the holding plate 8a.

[0031] A suction hole (not shown) is formed inside the frame 6a, one end of which is connected to the bottom of the recess 60a of the frame 6a. The other end of the suction hole is connected to a suction path (not shown) which is connected to a suction source (not shown). A valve (not shown) is provided in the suction path, and when the valve is opened, negative pressure from the suction source acts on the upper surface 80a of the holding plate 8a through the suction path and the suction hole. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used. However, a rotary pump or the like may also be used as the suction source.

[0032] The mounter device 2a has a roller 10a. The roller 10a is cylindrical and made of metal such as stainless steel. The roller 10a is oriented so that its long axis is parallel to the upper surface 80a of the holding plate 8a (along the X1 axis). The roller 10a is rotatable around an axis that is parallel to the long axis (along the X1 axis).

[0033] The mounter device 2a also includes a Y1-axis movement mechanism that moves one or both of the rollers 10a and the holding table 4a in a direction perpendicular to the longitudinal direction of the rollers 10a and parallel to the upper surface 80a of the holding plate 8a (a direction along the Y1 axis). The Y1-axis movement mechanism is, for example, a ball screw-type movement mechanism equipped with a ball screw. The Y1-axis movement mechanism moves the rollers 10a and the holding table 4a relatively in a direction along the Y1 axis.

[0034] Furthermore, the mounter device 2a has a cutter (not shown). The cutter can cut the strip-shaped second tape 17 attached to the wafer 11 into an appropriate shape and size. Alternatively, the mounter device 2a attaches the second tape 17, which has been cut into an appropriate shape and size in advance, to the wafer 11.

[0035] Above the holding table 4a, one or more transfer mechanisms (not shown) capable of transferring the wafer 11 to the holding table 4a, etc., are arranged. The wafer 11 may be transferred to the holding table 4a manually by an operator. In this case, the transfer mechanism for transferring the wafer 11 can be omitted.

[0036] The second tape application step S1 is performed in the mounter apparatus 2a described above. In the second tape application step S1, first, the wafer 11 is held by the holding table 4a. Specifically, the wafer 11 is placed on the holding table 4a by a transport mechanism (not shown) so that the first surface 11a of the wafer 11 is exposed upward and the second surface 11b faces the upper surface 80a. Thereafter, by operating a suction source, a valve, etc., negative pressure from the suction source is applied to the upper surface 80a of the holding plate 8a through a suction path, etc. As a result, the wafer 11 is sucked and held by the holding table 4a.

[0037] Next, the second tape 17 is attached to the first surface 11a of the wafer 11. The second tape 17 is, for example, a tape including a film-like substrate and an adhesive layer (glue layer) provided on the substrate. The substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. The adhesive layer may be made of an ultraviolet-curing resin that hardens when irradiated with ultraviolet light.

[0038] The second tape 17 is placed on the first surface 11a, and while the roller 10a presses the second tape 17 against the first surface 11a of the wafer 11, the roller 10a and the holding table 4a are moved relatively in a direction parallel to the upper surface 80a of the holding plate 8a (direction along the Y1 axis). As a result, the second tape 17 is adhered to the first surface 11a of the wafer 11.

[0039] If the second tape 17 is not pre-cut into a shape and size corresponding to the wafer 11 but is in a strip shape, the second tape 17 attached to the wafer 11 is cut by a cutter into a shape and size corresponding to the wafer 11. In this way, the wafer 11 having the second tape 17 attached to its first surface 11a is obtained.

[0040] Next, a grinding step S2 is performed. In the grinding step S2, the wafer 11 is thinned to a predetermined thickness. Figure 5 is a partial cross-sectional side view of the grinding device 20 and the wafer 11 in the grinding step S2. As shown in Figure 5, the grinding device 20 has a holding table 22.

[0041] The holding table 22 has a configuration similar to that of the holding table 4a included in the mounter device 2a. That is, the holding table 22 includes a disk-shaped frame 24 made of a metal such as stainless steel. A recess 24a having a circular opening at the top end is formed on the upper surface of the frame 24. A disk-shaped holding plate 26 that matches the shape of the recess 24a is fitted into the recess 24a. The holding plate 26 is a plate-shaped porous member made of a material such as ceramics. The holding table 22 holds the wafer 11 placed on the upper surface (holding surface) 26a of the holding plate 26.

[0042] A suction hole (not shown) is formed inside the frame 24, one end of which is connected to the bottom of the recess 24a of the frame 24. The other end of the suction hole is connected to a suction path (not shown) which is connected to a suction source (not shown). A valve (not shown) is provided in the suction path, and when the valve is opened, negative pressure from the suction source acts on the upper surface 26a of the holding plate 26 through the suction path and the suction hole. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used. However, a rotary pump or the like may also be used as the suction source.

[0043] The holding table 22 is connected to a rotary drive source (not shown) such as a motor. Due to the rotary drive force obtained by the rotary drive source, the holding table 22 rotates around a rotation axis that passes through the center of the upper surface 26a and is parallel to a direction perpendicular to the upper surface 26a (a direction along the Z2 axis).

[0044] The grinding device 20 includes a grinding unit 28. The grinding unit 28 has an annular grinding wheel 32 and a plurality of grinding stones 34 arranged in a ring shape around the outer periphery of the grinding wheel 32. The grinding unit 28 also has a spindle 30. One end of the spindle 30 is connected to the grinding wheel 32. The other end of the spindle 30 is connected to a rotational drive source (not shown) such as a motor. Due to the rotational drive force obtained from the rotational drive source, the spindle 30 and the grinding wheel 32 rotate around a rotation axis that passes through the center of the spindle and runs along the longitudinal direction of the spindle 30.

[0045] The grinding device 20 also includes a Z2-axis movement mechanism that moves one or both of the holding table 22 and the grinding unit 28 in a direction perpendicular to the upper surface 26a (along the Z2 axis). The Z2-axis movement mechanism is, for example, a ball screw-type movement mechanism equipped with a ball screw. The Z2-axis movement mechanism moves the holding table 22 and the grinding unit 28 relative to each other in the direction along the Z2 axis.

[0046] Above the holding table 22, one or more transfer mechanisms (not shown) capable of transferring the wafer 11 to the holding table 22, etc., are arranged. Note that the transfer of the wafer 11 to the holding table 22 may be performed manually by an operator. In this case, the transfer mechanism for transferring the wafer 11 can be omitted.

[0047] The grinding step S2 is performed by the grinding apparatus 20 described above. In the grinding step S2, first, the wafer 11 is held by the holding table 22. Specifically, the wafer 11 is placed on the holding table 22 by a transfer mechanism (not shown) so that the second surface 11b of the wafer 11 is exposed upward and the first surface 11a faces the upper surface 26a. Thereafter, by operating a suction source, a valve, etc., negative pressure from the suction source is applied to the upper surface 26a of the holding plate 26 through a suction path, etc. As a result, the wafer 11 is sucked and held by the holding table 22.

[0048] Next, the rotation drive source is operated to rotate the spindle 30 around the rotation axis. This causes the grinding wheel 32 (grinding stone 34) to rotate around the rotation axis. With the grinding wheel 32 (grinding stone 34) rotating around the rotation axis, the Z2-axis movement mechanism moves the holding table 22 and the grinding unit 28 relatively along the Z2 axis. This causes the lower surface of the grinding stone 34 to come into contact with the second surface 11b of the wafer 11, and the second surface 11b is ground. By the grinding step S2, the wafer 11 is thinned to a predetermined thickness.

[0049] Next, a deteriorated layer forming step S3 is performed. In the deteriorated layer forming step S3, an deteriorated layer that serves as a dividing starting point is formed inside the wafer 11. The deteriorated layer forming step S3 is performed by a laser irradiation device. FIG. 6 is a perspective view of the laser irradiation device 40 and the wafer 11 in the deteriorated layer forming step S3, and FIG. 7 is a cross-sectional view of the laser irradiation device 40 and the wafer 11 in the deteriorated layer forming step S3. First, the laser irradiation device 40 will be described.

[0050] As shown in FIGS. 6 and 7, the laser irradiation device 40 has a holding table 42. The holding table 42 has a configuration similar to that of the holding table 4a included in the mounter device 2a. That is, the holding table 42 includes a disk-shaped frame 44 made of a metal such as stainless steel. A recess 44a having a circular opening at the top end is formed on the upper surface of the frame 44. A disk-shaped holding plate 46 that matches the shape of the recess 44a is fitted into the recess 44a. The holding plate 46 is a plate-shaped porous member made of a material such as ceramics. The holding table 42 holds the wafer 11 placed on the upper surface (holding surface) 46a of the holding plate 46.

[0051] A suction hole (not shown) is formed inside the frame 44, one end of which is connected to the bottom of the recess 44a of the frame 44. The other end of the suction hole is connected to a suction path (not shown) which is connected to a suction source (not shown). A valve (not shown) is provided in the suction path, and when the valve is opened, negative pressure from the suction source acts on the upper surface 46a of the holding plate 46 through the suction path and the suction hole. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used. However, a rotary pump or the like may also be used as the suction source.

[0052] The holding table 42 is also connected to a rotary drive source (not shown). Due to the rotary drive force obtained by the rotary drive source, the holding table 42 rotates around a rotation axis that passes through the center of the upper surface 46a and is parallel to a direction perpendicular to the upper surface 46a (a direction along the Z3 axis).

[0053] The laser irradiation device 40 has a laser irradiation unit 48 that irradiates the wafer 11 held by the holding table 42 with a laser beam 25. The laser irradiation unit 48 includes a laser oscillator (not shown). The laser oscillator includes a laser medium such as Nd:YAG that is suitable for laser oscillation.

[0054] The laser irradiation unit 48 also includes a processing head (laser processing head) 50. The laser irradiation unit 48 also includes a deflector (not shown) and a condenser (not shown) that guide a laser beam generated by laser oscillation of the laser oscillator to the processing head 50. The laser beam 25 generated by the laser oscillator is irradiated onto the wafer 11 held by the holding table 42 via the deflector, condenser, and processing head 50, thereby laser processing the wafer 11.

[0055] The laser irradiation device 40 has a processing head moving mechanism (not shown) that moves the laser irradiation unit 48 (processing head 50) along the Z3 axis. The processing head moving mechanism is, for example, a ball screw type moving mechanism equipped with a ball screw. By moving (raising and lowering) the processing head 50 along the Z3 axis using the processing head moving mechanism, the height position of the focal point of the laser beam 25 emitted from the processing head 50 is adjusted.

[0056] 6, a camera 52 capable of capturing images of the wafer 11 held on the holding table 42 is disposed adjacent to the processing head 50 in a direction parallel to the upper surface 46a of the holding plate 46 (the direction along the X3 axis). The irradiation position of the laser beam 25 is determined by referring to the image captured by the camera 52. The camera 52, like the processing head 50, is connected to the processing head moving mechanism. Therefore, the processing head moving mechanism moves the camera 52 along the Z3 axis together with the processing head 50.

[0057] The laser irradiation device 40 has an X3-axis movement mechanism (not shown) that moves the holding table 42 and the processing head 50 relatively along a direction (direction along the X3 axis) parallel to the upper surface 46a of the holding plate 46. The laser irradiation device 40 also has a Y3-axis movement mechanism (not shown) that moves the holding table 42 and the processing head 50 relatively along a direction (direction along the Y3 axis) that is parallel to the upper surface 46a of the holding plate 46 and perpendicular to the direction along the X3 axis.

[0058] The X3-axis movement mechanism and the Y3-axis movement mechanism are, for example, ball screw-type movement mechanisms equipped with ball screws. By irradiating the laser beam 25 onto the wafer 11 while moving the holding table 42 and the processing head 50 relative to each other using the X3-axis movement mechanism and the Y3-axis movement mechanism, it is possible to laser process a predetermined position of the wafer 11 held on the holding table 42. Below, an example will be described in which the holding table 42 is moved by the X3-axis movement mechanism and the Y3-axis movement mechanism.

[0059] Above the holding table 42, one or more transport mechanisms (not shown) capable of transporting the wafer 11 to the holding table 42 or the like are arranged. For example, the wafer 11 is placed on the upper surface 46a of the holding table 42 so that the second surface 11b is exposed upward and the first surface 11a to which the second tape 17 is attached faces the upper surface 46a. The wafer 11 may be transported to the holding table 42 manually by an operator. In this case, the transport mechanism for transporting the wafer 11 can be omitted.

[0060] The deteriorated layer forming step S3 is performed by the laser irradiation device 40 described above. In the deteriorated layer forming step S3, the wafer 11 is held by the holding table 42. Specifically, the wafer 11 is placed on the holding table 42 so that the second tape 17 attached to the first surface 11a of the wafer 11 contacts the upper surface 46a. Thereafter, by operating the suction source, a valve, etc., the negative pressure of the suction source is applied to the upper surface 46a of the holding plate 46 through the suction path, etc. As a result, the wafer 11 is sucked and held by the holding table 42.

[0061] Next, the wafer 11 is irradiated with a laser beam 25 along the planned dividing lines 13. Specifically, first, a rotary drive source connected to the holding table 42 rotates the holding table 42 so that the planned dividing lines 13a are parallel to the X3 axis.

[0062] Next, the positional relationship between the processing head 50 of the laser irradiation unit 48 and the wafer 11 is adjusted. Specifically, the position of the holding table 42 is adjusted by the Y3-axis movement mechanism so that the processing head 50 of the laser irradiation unit 48 overlaps with an extension of one of the planned dividing lines 13a outside the wafer 11.

[0063] The height of the processing head 50 is adjusted by the processing head moving mechanism to position the height of the focal point of the laser beam 25 at a predetermined height position. Here, this predetermined height position is a height position at which an affected layer can be formed at a predetermined position inside the wafer 11 when the laser beam 25 is focused on the focal point with the focal point positioned inside the wafer 11.

[0064] Next, the processing head 50 starts emitting a laser beam 25 onto the wafer 11. The wavelength of the laser beam 25 is a wavelength that can pass through the wafer 11. With the height position of the focal point of the laser beam 25 adjusted to a predetermined height, the holding table 42 is moved in the direction along the X3 axis by the X3-axis movement mechanism. As a result, the laser beam 25 is focused inside the wafer 11 and irradiated along one of the planned dividing lines 13a. As a result, an affected layer 27 is formed inside the wafer 11 along the planned dividing line 13a.

[0065] When the material of the wafer 11 is sapphire, the irradiation conditions of the laser beam 25 are preferably set as follows: For example, the wavelength of the laser beam 25 is preferably set to 515 nm to 1064 nm, the pulse width is preferably set to 250 fs to 10 ps, ​​the output is preferably set to 0.01 to 10 W, the repetition frequency is preferably set to 10 kHz to 500 kHz, the NA (Numerical Aperture) of the condenser lens is preferably set to 0.6 to 0.8, and the feed speed of the wafer 11 is preferably set to 10 mm / s to 2000 mm / s.

[0066] The output of the laser beam 25 is adjusted appropriately according to the wavelength band, pulse width, etc. of the laser beam 25, and the feed speed is adjusted appropriately according to the frequency, etc. Specifically, the wavelength is set to 1064 nm, the pulse width to 1 ps, the output to 0.5 W, the frequency to 10 kHz, and the feed speed to 800 mm / s. However, the irradiation conditions of the laser beam 25, etc., can be changed within a range in which the affected layer 27 is appropriately formed inside the wafer 11.

[0067] After the laser beam 25 is irradiated from one end of one of the division lines 13a to the other end thereof to form the affected layer 27, the movement of the holding table 42 in the direction along the X3 axis is stopped, and the emission of the laser beam 25 from the processing head 50 is stopped.

[0068] Next, the holding table 42 is moved by the Y3-axis movement mechanism so that the end of another unprocessed dividing line 13a overlaps with the processing head 50. Then, emission of the laser beam 25 from the processing head 50 is started, and the holding table 16 is moved in the direction along the X3 axis. As a result, a deteriorated layer 27 is similarly formed inside the wafer 11. By repeating the same procedure, deteriorated layers 27 are formed along all of the mutually parallel dividing lines 13a among the dividing lines 13 set on the first surface 11a of the wafer 11.

[0069] Next, the holding table 42 holding the wafer 11 is rotated 90 degrees around a rotation axis along the Z3 axis, and the deteriorated layers 27 are similarly formed along the dividing lines 13b perpendicular to the dividing lines 13a described above. In the deteriorated layer forming step S3, the wafer 11 is laser processed along all of the dividing lines 13 set on the wafer 11 in this manner, to form the deteriorated layers 27. There is no particular restriction on the order in which the deteriorated layers are formed; for example, the deteriorated layers may be formed along the dividing lines 13b and then along the dividing lines 13a.

[0070] Next, a first tape application step S4 is performed. In the first tape application step S4, a first tape is applied to the second surface 11b of the wafer 11. The first tape application step S4 is performed by a mounter device. FIG. 8 is a perspective view of the mounter device 2b, the wafer 11, and the frame 21 in the first tape application step S4, and FIG. 9 is a cross-sectional view of the mounter device 2b, the wafer 11, and the frame 21 in the first tape application step S4.

[0071] The mounter device 2b used in the first tape application step S4 is configured similarly to the mounter device 2a used in the second tape application step S1. Therefore, the above description of the mounter device 2a will be referred to as the description of the mounter device 2b as appropriate. As shown in Fig. 9, the mounter device 2b has a holding table 4b. Note that the holding table 4b is not shown in Fig. 8.

[0072] The holding table 4b has a configuration similar to that of the holding table 4a included in the mounter apparatus 2a. That is, the holding table 4b includes a disk-shaped frame 6b made of a metal such as stainless steel. A recess 60b with a circular opening at the top end is formed on the upper surface of the frame 6b. A disk-shaped holding plate 8b matching the shape of the recess 60b is fitted into the recess 60b. The holding plate 8b is a plate-shaped porous member made of a material such as ceramics. The holding table 4b holds the wafer 11 placed on the upper surface (holding surface) 80b of the holding plate 8b.

[0073] A suction hole (not shown) is formed inside the frame 6b, one end of which is connected to the bottom of the recess 60b of the frame 6b. The other end of the suction hole is connected to a suction path (not shown) which is connected to a suction source (not shown). A valve (not shown) is provided in the suction path, and when the valve is opened, negative pressure from the suction source acts on the upper surface 80b of the holding plate 8b through the suction path and the suction hole. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used. However, a rotary pump or the like may also be used as the suction source.

[0074] The mounter device 2b has rollers 10b. The rollers 10b are cylindrical and made of metal such as stainless steel. The rollers 10b are oriented so that their long axis direction is parallel to the upper surface 80b of the holding plate 8b (along the X4 axis). The rollers 10b are rotatable around an axis that is parallel to the long axis direction (along the X4 axis).

[0075] The mounter device 2b also includes a Y4-axis movement mechanism that moves one or both of the rollers 10b and the holding table 4b in a direction perpendicular to the longitudinal axis of the rollers 10b and parallel to the upper surface 80b of the holding plate 8b (the direction along the Y4 axis). The Y4-axis movement mechanism is, for example, a ball screw-type movement mechanism equipped with a ball screw. The Y4-axis movement mechanism moves the rollers 10b and the holding table 4b relatively in the direction along the Y4 axis.

[0076] The mounter device 2b includes a support member 12a. The support member 12a is made of a metal such as stainless steel and is a cylindrical member that surrounds the holding table 4b. The mounter device 2b includes a Z4-axis movement mechanism that moves the support member 12a in a direction perpendicular to the upper surface 80b of the holding plate 8b (a direction along the Z4 axis). The Z4-axis movement mechanism is, for example, a ball-screw type movement mechanism that includes a ball screw.

[0077] Furthermore, the mounter device 2b has a cutter (not shown). The cutter can cut the strip-shaped first tape 19 attached to the wafer 11 into an appropriate shape and size. Alternatively, the mounter device 2b attaches the first tape 19, which has been cut out in advance to an appropriate shape and size, to the wafer 11.

[0078] Above the holding table 4b, one or more transfer mechanisms (not shown) capable of transferring the wafer 11 to the holding table 4b are arranged. The wafer 11 may be transferred to the holding table 4b manually by an operator. In this case, the transfer mechanism for transferring the wafer 11 can be omitted.

[0079] The first tape application step S4 is performed in the mounter apparatus 2b described above. In the first tape application step S4, the wafer 11 is held by the holding table 4b. Specifically, the wafer 11 is placed on the holding table 4b by a transport mechanism (not shown) so that the second tape 17 applied to the first surface 11a of the wafer 11 contacts the upper surface 80b. Thereafter, the suction source is activated, and the negative pressure of the suction source acts on the upper surface 80b of the holding plate 8b through a flow path or the like. As a result, the wafer 11 is sucked and held by the holding table 4b.

[0080] Next, a frame 21 is prepared. The frame 21 is made of a metal such as SUS (stainless steel), and has a circular ring-shaped first surface 21a and a circular ring-shaped second surface 21b opposite the first surface 21a. A cylindrical opening 21c penetrating the frame 21 in the thickness direction is provided in the center of the frame 21. The diameter of the opening 21c is larger than the diameter of the wafer 11 (the width of the first surface 11a and the second surface 11b).

[0081] The second surface 21b of the frame 21 is placed on the support member 12a so that the wafer 11 fits into the opening 21c of the frame 21. At this time, the position of the support member 12a in the direction along the Z4 axis is adjusted by the Z4 axis movement mechanism so that the heights of the first surface 21a and the second surface 11b of the wafer 11 are equal.

[0082] Next, the first tape 19 is attached to the second surface 11b of the wafer 11. The first tape 19 is, for example, a tape including a film-like substrate and an adhesive layer (glue layer) provided on the substrate. The substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. The substrate is preferably made of a material that is relatively hard so as to minimize vibration when the cutting blade cuts into the first tape 19 in the cutting step S7 described below. From this perspective, polyethylene terephthalate is more preferable for the first tape 19. The adhesive layer may be made of an ultraviolet-curable resin that is cured by irradiation with ultraviolet light.

[0083] The first tape 19 is placed on the second surface 11b, and the roller 10b rotates while pressing the first tape 19 against the second surface 11b of the wafer 11 and the first surface 21a of the frame 21, and the roller 10b and the holding table 4b move relatively in the direction along the Y4 axis. As a result, the first tape 19 is adhered to the second surface 11b of the wafer 11 and the first surface 21a of the frame 21. The first tape 19 is cut by a cutter to an appropriate size and shape to match the size (width) and shape of the frame 21. By the first tape adhering step S4 described above, the first tape 19 is adhered to the wafer 11 and the frame 21, and the wafer 11 is integrated with the frame 21 via the first tape 19.

[0084] After the first tape application step S4, a second tape peeling step S5 is performed. In the second tape peeling step S5, the second tape 17 attached to the wafer 11 is peeled off. The second tape peeling step S5 is performed by a peeling device. FIG. 10 is a perspective view of the peeling device 2c, the wafer 11, and the frame 21 in the second tape peeling step S5, and FIG. 11 is a cross-sectional view of the peeling device 2c, the wafer 11, and the frame 21 in the second tape peeling step S5. As shown in FIG. 11, the peeling device 2c has a holding table 4c. Note that the holding table 4c is not shown in FIG. 10.

[0085] The holding table 4c has a configuration similar to that of the holding table 4b included in the mounter device 2b. For example, it includes a disk-shaped frame 6c made of a metal such as stainless steel. A recess 60c with a circular opening at the top end is formed on the upper surface of the frame 6c. A disk-shaped holding plate 8c matching the shape of the recess 60c is fitted into the recess 60c. The holding plate 8c is a plate-shaped porous member made of, for example, a material such as ceramics. The holding table 4c holds the wafer 11 placed on the upper surface (holding surface) 80c of the holding plate 8c.

[0086] A suction hole (not shown) is formed inside the frame 6c, one end of which is connected to the bottom of the recess 60c of the frame 6c. The other end of the suction hole is connected to a suction path (not shown) which is connected to a suction source (not shown). A valve (not shown) is provided in the suction path, and when the valve is opened, negative pressure from the suction source acts on the upper surface 80c of the holding plate 8c through the suction path and the suction hole. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used. However, a rotary pump or the like may also be used as the suction source.

[0087] Above the holding table 4c, one or more transport mechanisms (not shown) capable of transporting the wafer 11 to the holding table 4c, etc., are disposed. For example, the wafer 11 transported by the transport mechanism is placed on the upper surface 80c of the holding table 4c so that the second tape 17 attached to the first surface 11a is exposed upward and the first tape 19 attached to the second surface 11b is in contact with the upper surface 80c. The wafer 11 may be transported to the holding table 4c manually by an operator. In this case, the transport mechanism for transporting the wafer 11 can be omitted.

[0088] The peeling device 2c also includes a peeling mechanism (not shown). The peeling mechanism, for example, adheres an adhesive peeling tape to the second tape 17 attached to the wafer 11, and peels the second tape 17 from the wafer 11 by lifting the adhesive peeling tape up relative to the wafer 11. More specifically, the adhesive peeling tape is adhered to an end of the second tape 17, and the second tape 17 is sequentially peeled from the wafer 11 from that end to another end.

[0089] The second tape peeling step S5 is performed by the peeling apparatus 2c described above. In the second tape peeling step S5, the wafer 11 is held by the holding table 4c. Specifically, the wafer 11 is placed on the holding table 4c by a transport mechanism (not shown) so that the second surface 11b of the wafer 11 faces the upper surface 80c. However, the wafer 11 may also be placed on the holding table 4c manually by an operator. Thereafter, the suction source is activated, and the negative pressure of the suction source acts on the upper surface 80c of the holding plate 8c through a flow path or the like. As a result, the wafer 11 is sucked and held by the holding table 4c.

[0090] Next, one end of the second tape 17 is lifted by the peeling mechanism, and the second tape 17 is peeled from the first surface 11a of the wafer 11 from that end to the other end. However, the second tape 17 may also be peeled manually by an operator.

[0091] Through the above-described first tape application step S4 and second tape separation step S5, the tape applied to wafer 11 is replaced from second tape 17 to first tape 19. Note that the order of first tape application step S4 and second tape separation step S5 may be reversed. That is, first tape application step S4 may be performed after second tape separation step S5.

[0092] Next, a gap forming step S6 is performed. In the gap forming step S6, a crack is first formed starting from the affected layer 27 formed on the wafer 11. The crack is formed by a braking device. FIG. 12 is a partial cross-sectional side view of the braking device 60, the wafer 11, and the frame 21 in the gap forming step S6. As shown in FIG. 12, the braking device 60 has a holding table 62 that holds the wafer 11. The holding table 62 has a support member 64. The support member 64 is a cylindrical member made of a metal such as stainless steel.

[0093] A plurality of clamps 66 are provided on the upper surface 64a of the support member 64. The clamps 66 are arranged, for example, on concentric circles at equal intervals on the upper surface 64a of the support member 64. For example, four clamps 66 are arranged at 90-degree intervals on the upper surface 64a of the support member 64. Two fixing clamps 66 are shown in Figure 12.

[0094] Some of the multiple clamps 66 are fixed clamps that are fixed to the support member 64. On the other hand, the remaining clamps 66 are movable clamps that can move toward the center of the support member 64. For example, of the four clamps 66, two adjacent clamps are fixed clamps and the other two adjacent clamps are movable clamps.

[0095] The braking device 60 includes a Y6-axis movement mechanism (not shown) that moves the holding table 62 along the Y6 axis parallel to the upper surface 64a. The Y6-axis movement mechanism is, for example, a ball screw-type movement mechanism equipped with a ball screw. The Y6-axis movement mechanism moves the support member 64 relative to a lower unit 68 and an upper unit 74 (described later) in a direction along the Y6 axis. The support member 64 is also connected to a rotary drive source (not shown). The rotary drive force obtained by the rotary drive source causes the support member 64 to rotate around a rotation axis that passes through the center of the upper surface 64a and is parallel to the direction along the Z6 axis.

[0096] 12, a lower unit 68 is disposed below the support member 64. The lower unit 68 cooperates with an upper pressing bar 84 provided in an upper unit 74 (described later) to clamp the wafer 11. The lower unit 68 includes a plurality of lower pressing bars 72 and a bar holding member 70 to which each lower pressing bar 72 is fixed.

[0097] More specifically, as shown in Fig. 12, the lower unit 68 has four lower pressure bars 72a, 72b, 72c, and 72d, each of which has a different length in the direction along the X6 axis, which is parallel to the upper surface 64a and perpendicular to the Y6 axis. One end of the lower pressure bars 72a, 72b, 72c, and 72d has a stepped shape. The other ends of the lower pressure bars 72a, 72b, 72c, and 72d are fixed to a spherical bar holding member 70. The lower pressure bars 72a, 72b, 72c, and 72d are fixed to the bar holding member 70 at equal intervals (90-degree intervals).

[0098] The braking device 60 includes a lower unit moving mechanism (not shown) that moves the lower unit 68 along the Z6 axis, which is perpendicular to the X6 axis and the Y6 axis. The lower unit moving mechanism is, for example, a ball screw type moving mechanism. The lower unit moving mechanism moves the bar holding member 70 along the Z6 axis.

[0099] The bar holding member 70 is also connected to a rotary drive source (not shown). The rotary drive force from the rotary drive source causes the bar holding member 70 to rotate around a rotation axis passing through the center of the bar holding member 70. Rotating the bar holding member 70 switches between the lower pressure bars 72a, 72b, 72c, and 72d that cooperate with an upper pressure bar 84 provided in an upper unit 74 (described below).

[0100] As shown in Fig. 12, an upper unit 74 is disposed above the holding table 62. An L-shaped slider 76 is disposed in the upper unit 74, and extends mainly along the Y6 axis. An upper pressing bar 84 is fixed to the slider 76 via a support member 82. The slider 76 is also provided with a damper 86 connected to the support member 82. The damper 86 is formed of, for example, an air cylinder or a coil spring, and serves to urge the upper pressing bar 84 downward with a constant force in a direction along the Z6 axis.

[0101] Additionally, a blade 80 is slidably disposed on the slider 76 via a gap adjustment portion 78. The blade 80 has a shape that narrows toward the tip (lower end), and is adjacent to the upper pressing bar 84 in the direction along the Y6 axis.

[0102] The braking device 60 is equipped with a gap adjustment unit movement mechanism (not shown) that can move the gap adjustment unit 78 in a direction along the Y6 axis. The gap adjustment unit movement mechanism is, for example, a ball screw type movement mechanism equipped with a ball screw. The gap adjustment unit movement mechanism moves the gap adjustment unit 78 along the slider 76. By sliding the gap adjustment unit 78 relative to the slider 76, the gap between the blade 80 and the upper pressure bar 84 can be adjusted.

[0103] The braking device 60 includes an upper unit moving mechanism (not shown) that moves the upper unit 74 along the Z6 axis. The upper unit moving mechanism is, for example, a ball screw type moving mechanism that includes a ball screw. The upper unit moving mechanism moves the upper unit 74 in a direction along the Z6 axis.

[0104] The breaking device 60 is also provided with one or more transport mechanisms (not shown) that can transport the wafer 11 to the support member 64 or the like. For example, the wafer 11 transported by the transport mechanism is placed on the upper surface 64a of the support member 64 so that the first surface 11a is exposed upward and the first tape 19 attached to the second surface 11b faces the upper surface 64a. The wafer 11 may be transported to the holding table 62 manually by an operator. In this case, the transport mechanism that transports the wafer 11 can be omitted.

[0105] The breaking device 60 described above forms cracks in the wafer 11, starting from the affected layer 27. When forming cracks in the wafer 11 in the gap forming step S6, the wafer 11 is first held by the holding table 62. Specifically, the wafer 11 is placed inside four clamps 66 provided on the support member 64 by a conveying mechanism (not shown) so that the first surface 11a is exposed upward and the first tape 19 attached to the second surface 11b of the wafer 11 faces the upper surface 64a.

[0106] Thereafter, the movable clamps 66 are urged toward the center of the upper surface 64a, and the wafer 11 is pressed against the fixed clamps 66. As a result, the wafer 11 is fixed and held on the holding table 62 by the four clamps 66. Next, a rotation drive source connected to the support member 64 rotates the support member 64 so that the planned dividing line 13a is parallel to the direction along the X6 axis.

[0107] Next, the Y6-axis movement mechanism moves the holding table 62 in the direction along the Y6 axis. The Y6-axis movement mechanism then adjusts the position of the holding table 62 so that a portion of the wafer 11 is positioned between the lower pressing bar 72 and the upper pressing bar 84 a predetermined distance away from the affected layer 27. In this state, the lower unit 68 is raised along the Z6 axis, and the upper unit 74 is lowered along the Z6 axis.

[0108] At this time, the damper 86 operates, and the upper pressure bar presses the wafer 11 downward along the Z6 axis with a constant force. In this way, the wafer 11 is clamped between the lower pressure bar 72 and the upper pressure bar 84 with a predetermined force.

[0109] In this state, the upper unit moving mechanism is actuated, and the blade 80 is lowered in the direction along the Z6 axis via the gap adjustment part 78. As a result, the tip of the blade 80 presses against a part of the wafer 11.

[0110] When the wafer 11 is fixed by the lower pressure bar 72 and the upper pressure bar 84 and further pressed by the blade 80, cracks 29 originating from the deteriorated layer 27 are generated inside the wafer 11 and extend in the thickness direction of the wafer 11. Then, the cracks 29 extend to the first surface 11a and the second surface 11b of the wafer 11, forming gaps 31 along each of the planned division lines 13. As a result, the wafer 11 is divided into individual chips 33.

[0111] Here, the distance between the blade 80 and the upper pressing bar 84 in the direction along the Y6 axis is adjusted in advance to a distance that allows cracks 29 to be efficiently formed by pressing the wafer 11 with the blade 80. Then, the Y6-axis moving mechanism moves the holding table 62, and pressing along all of the affected layers 27 divides the wafer 11 into a plurality of chips 33. The affected layers 27 remain on the sides of the chips 33 formed at this time.

[0112] In gap forming step S6, the first tape 19 is expanded to widen the gaps 31 between the chips 33. The expansion of the first tape 19 is performed by an expansion device. FIGS. 13 and 14 are partial cross-sectional side views of the expansion device 90, wafer 11, and frame 21 in gap forming step S6. FIG. 13 is a view before the first tape 19 is expanded, and FIG. 14 is a view after the first tape 19 is expanded. Note that in FIGS. 13 and 14, the affected layers 27 formed on the side surfaces of each chip 33 are omitted for ease of viewing. In reality, the surfaces of each chip 33 on which the affected layers 27 are formed face each other across the gap 31.

[0113] 13 and 14, the expansion device 90 has a holding table 92. The holding table 92 is a cylindrical member made of metal such as stainless steel. A first surface (top surface) 92a of the holding table 92 is provided with a plurality of clamps 94 that grip and fix the frame 21.

[0114] The expansion device 90 has a pressing mechanism (Z7-axis movement mechanism) 96. The pressing mechanism 96 is disposed surrounded by a cylindrical holding table 92. The pressing mechanism 96 is, for example, a movement mechanism equipped with an air cylinder. As the pressing mechanism 96 moves upward along the Z7 axis perpendicular to the upper surface 92a of the holding table 92, the first tape 19 is pressed by the pressing mechanism 96 inside the frame 21 supported by the holding table 92.

[0115] Above the holding table 92, one or more transport mechanisms (not shown) capable of transporting the wafer 11 to the holding table 92 or the like are disposed. For example, the wafer 11 transported by the transport mechanism is placed on the upper surface 92a so that the first surface 11a side is exposed upward and the first tape 19 attached to the second surface 21b of the frame 21 is in contact with the upper surface 92a. Note that the wafer 11 may be transported to the holding table 92 manually by an operator. In this case, the transport mechanism for transporting the wafer 11 can be omitted.

[0116] In the step of expanding the first tape 19, first, the wafer 11 is held by the holding table 92. Specifically, the wafer 11 is placed on the upper surface 92a of the holding table 92 so that the side of the first tape 19 attached to the second surface 21b of the frame 21 faces the upper surface 92a. Then, the first surface 21a side of the frame 21 is pressed downward by the clamp 94. This fixes the wafer 11 to the holding table 92.

[0117] Next, as shown in FIG. 14, the pressing mechanism 96 moves up along the Z7 axis. This presses the first tape 19 upward inside the frame 21 supported by the holding table 92. When the first tape 19 is pressed upward, as shown in FIG. 14, the first tape 19 is stretched from the portion fixed to the clamp 94. Then, the portion of the first tape 19 that is in contact with the pressing mechanism 96 expands radially outward on the X7Y7 plane. As a result, the gaps 31 between the chips 33 widen.

[0118] It should be noted that there are cases where cracks 29 can be formed in the wafer 11 and the wafer can be divided using only the expanding device 90, without using the breaking device 60. For example, when the first tape 19 is expanded by the expanding device 90, a force acts on the wafer 11, causing a crack to extend from the deteriorated layer 27 inside the wafer 11, and the wafer 11 is divided. In this case, the step using the breaking device 60 can be omitted.

[0119] Next, a cutting step S7 is performed in which the side surface of each chip 33 on which the affected layer 27 remains is cut. The cutting step S7 is performed by a cutting device that cuts the workpiece with an annular cutting blade. FIG. 15 is a perspective view of the cutting device 100, wafer 11, and frame 21 in the cutting step S7, and FIG. 16 is a partially sectional side view of the cutting device 100, wafer 11, and frame 21 in the cutting step S7. As shown in FIG. 16, the cutting device 100 has a holding table 102. Note that FIG. 15 shows only a cutting blade portion 118 of a cutting unit 110, which will be described later.

[0120] The holding table 102 has a configuration similar to that of the holding table of the mounter apparatus 2a or the like described above. Specifically, the holding table 102 includes, for example, a disk-shaped frame 104 made of a metal such as stainless steel. A recess 104a having a circular opening at the top end is formed on the upper surface of the frame 104. A disk-shaped holding plate 106 that matches the shape of the recess 104a is fitted into the recess 104a. The holding plate 106 is, for example, a plate-shaped porous member made of a material such as ceramics. The holding table 102 holds the wafer 11 placed on the upper surface (holding surface) 106a of the holding plate 106.

[0121] A suction hole (not shown) is formed inside the frame 104, one end of which is connected to the bottom of the recess 104a of the frame 104. The other end of the suction hole is connected to a suction path (not shown) which is connected to a suction source (not shown). A valve (not shown) is provided in the suction path, and when the valve is opened, negative pressure from the suction source acts on the upper surface 106a of the holding plate 106 through the suction path and the suction hole. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used. However, a rotary pump or the like may also be used as the suction source.

[0122] The holding table 102 has a holding table moving mechanism (not shown) that moves the holding table 102 in a direction along the X8 axis. The holding table moving mechanism is, for example, a ball screw type moving mechanism equipped with a ball screw. By moving the holding table 102 along the X8 axis using the holding table moving mechanism, the wafer 11 (plurality of chips 33) held on the holding table 102 can be cut along the planned division lines 13a (gaps 31).

[0123] The holding table 102 is also connected to a rotary drive source (not shown). The rotary drive source provides a rotary drive force that causes the holding table 102 to rotate about a rotation axis that passes through the center of the upper surface 106a and is parallel to the Z8 axis. Clamps 108 that secure the wafer 11 are provided on the outer periphery of the holding table 102.

[0124] The cutting device 100 includes a cutting unit 110 that cuts the wafer 11 (chips 33) held by the holding table 102. The cutting unit 110 has a spindle 112 with an axis that is approximately parallel to the direction along the Y8 axis. A cutting blade 116 is attached to one end (tip) of the spindle 112, and the other end of the spindle 112 is rotatably housed in a spindle housing 114. A motor (not shown) that is a rotation drive source for the spindle 112 is housed in the spindle housing 114. The cutting blade 116 has a cutting edge 118. The cutting edge 118 is an annular member in which abrasive grains made of, for example, diamond or the like are dispersed and fixed by a binder such as metal, resin, or ceramic.

[0125] The cutting unit 110 also has a cutting unit moving mechanism (not shown) that moves the cutting unit 110 in directions along the Y8 axis and the Z8 axis. The cutting unit moving mechanism is, for example, a ball screw type moving mechanism equipped with a ball screw. The cutting unit 110 also has a nozzle (not shown) that supplies machining fluid. The nozzle supplies the machining fluid to the tip of the cutting blade 116 and the wafer 11.

[0126] Above the holding table 102, one or more transport mechanisms (not shown) are arranged that can transport the wafer 11 (plurality of chips 33) to the holding table 102 or the like. For example, the wafer 11 transported by the transport mechanism is placed on the upper surface 106a of the holding table 102 so that the first surface 11a is exposed upward and the first tape 19 attached to the second surface 11b faces the upper surface 106a. The wafer 11 may be transported to the holding table 102 manually by an operator. In this case, the transport mechanism that transports the wafer 11 can be omitted.

[0127] The cutting step S7 is performed by the above-described cutting device 100. In the cutting step S7, the wafer 11 is held by the holding table 102. Specifically, the wafer 11 is placed on the holding table 102 by a transport mechanism (not shown) so that the first tape 19 attached to the second surface 11b of the wafer 11 faces the upper surface 106a of the holding plate 106. Thereafter, the suction source is activated, and the negative pressure of the suction source acts on the upper surface 106a through a flow path or the like. As a result, the wafer 11 is sucked and held by the holding table 102.

[0128] Next, the chips 33 with the affected layers 27 remaining on their side surfaces are cut. Fig. 17 is a cross-sectional view of the wafer 11 (chips 33) in cutting step S7. As shown in Fig. 17, a first chip 33a and a second chip 33b adjacent to the first chip 33a are fixed to the first tape 19, with one planned division line 13 sandwiched between them. The affected layers 27 are formed on the side surfaces 35 and 37 of the first chip 33a and on the side surfaces 39 and 41 of the second chip 33b.

[0129] The cutting device 100 cuts the side surface 35 of the first chip 33a, the side surface 37 of the first chip 33a, the side surface 39 of the second chip 33b, and the side surface 41 of the second chip 33b in this order, thereby removing the affected layer 27. The procedure for cutting the side surface 35 of the first chip 33a and the side surface 39 of the second chip 33b will be described below.

[0130] The orientation of the holding table 102 is adjusted by the rotary drive source so that the side surface 37 of the first chip 33a is parallel to the direction along the X8 axis (see FIG. 16). Also, the positional relationship between the cutting blade 116 of the cutting unit 110 and the wafer 11 (chip 33) is adjusted. Specifically, the position of the holding table 102 in the direction along the X8 axis is adjusted by the holding table moving mechanism so that the cutting blade 116 does not overlap the wafer 11 when viewed from above.

[0131] Furthermore, the position of the cutting unit 110 in the Y8-axis direction is adjusted by the cutting unit moving mechanism so that the side surface 37 of the first tip 33a and the cutting blade 116 are aligned in position along the Y8 axis.

[0132] Furthermore, the position (height) of the cutting unit 110 in the direction along the Z8 axis is adjusted by the cutting unit moving mechanism so that the lower end of the cutting blade 116 is positioned slightly below the second surface 11b of the wafer 11. At this time, processing fluid is supplied from the nozzle to the tip of the cutting blade 116 and the wafer 11. Then, the motor, which is the rotation drive source, starts to rotate the cutting blade 116 together with the spindle.

[0133] Next, the holding table moving mechanism moves the holding table 102 along the X8 axis, and then moves the cutting blade 116 and the holding table 102 relatively along the X8 axis (processing feed).

[0134] 18 is a partial cross-sectional side view of the cutting blade 116, the wafer 11 (chip 33), and the first tape 19 in cutting step S7. By the above operation, while processing fluid is being supplied to the cutting blade 116 and the wafer 11, the first side surface 118a of the cutting edge portion 118 of the cutting blade 116 cuts into the affected layer 27 formed on the side surface 37 of the first chip 33a of the wafer 11.

[0135] The affected layer 27 is cut and removed by cutting the wafer 11 with the cutting blade 116 in the direction along the X8 axis. Figure 19 is a cross-sectional view of the wafer 11 in cutting step S7. Figure 19 shows the wafer 11 including a side surface 43 from which the affected layer 27 formed on the side surface 37 of the first chip 33a of the wafer 11 has been removed.

[0136] For example, if the material of the wafer 11 is sapphire, the thickness of the wafer 11 is 1000 μmm, and the thickness of the tape is 250 μm, the cutting depth of the cutting blade 116 (the cutting depth set in the cutting device 100, the distance from the first surface 11a of the wafer 11 to the tip of the cutting blade 116) is set to 1080 μm, the feed speed (the speed at which the holding table 102 is fed in the direction along the X8 axis) is set to 5 mm / sec, the rotation speed of the spindle 112 is set to 30,000 rpm, and the supply amount of the processing liquid is set to 4 L / min.

[0137] After the cutting blade 116 cuts the affected layer 27 formed on the side surface 37 of the first chip 33a, the movement of the holding table 102 along the X8 axis by the holding table moving mechanism stops. Then, the height of the cutting unit 110 is adjusted by the cutting unit moving mechanism so that the lower end of the cutting blade 116 is positioned a predetermined distance above the first surface 11a of the wafer 11.

[0138] Next, the holding table moving mechanism moves the holding table 102 along the X8 axis in the direction opposite to the processing feed direction. Specifically, the holding table moving mechanism adjusts the position of the holding table 102 along the X8 axis so that the cutting blade 116 moves relatively to a position where it does not overlap with the wafer 11 when viewed from above.

[0139] Next, the position of the cutting unit 110 in the direction along the Y8 axis is adjusted by the cutting unit moving mechanism so that the side surface 39 of the second tip 33b and the cutting blade 116 are aligned in the direction along the Y8 axis.

[0140] Furthermore, the height of the cutting unit 110 is adjusted by the cutting unit moving mechanism so that the lower end of the cutting blade 116 is positioned slightly below the second surface 11b of the wafer 11.

[0141] Then, in the same procedure as when cutting the affected layer 27 formed on the side surface 37 of the first chip 33a, the second side surface 118b side of the cutting edge portion 118 of the cutting blade 116 cuts into the affected layer 27 formed on the side surface 39 of the second chip 33b. Figure 20 is a partial cross-sectional side view of the cutting blade 116, the wafer 11, and the first tape 19 in cutting step S7. The cutting blade 116 cuts into the wafer 11 in the direction along the X8 axis, thereby cutting and removing the affected layer 27.

[0142] After the cutting blade 116 cuts the affected layer 27 formed on the side surface 39 of the second chip 33b, the movement of the holding table 102 along the X8 axis by the holding table moving mechanism stops. Then, the height of the cutting unit 110 is adjusted by the cutting unit moving mechanism so that the lower end of the cutting blade 116 is positioned a predetermined distance above the first surface 11a of the wafer 11.

[0143] Next, the holding table moving mechanism moves the holding table 102 along the X8 axis in the direction opposite to the processing feed direction. Specifically, the holding table moving mechanism adjusts the position of the holding table 102 along the X8 axis so that the cutting blade 116 moves relatively to a position where it does not overlap with the wafer 11 when viewed from above.

[0144] By repeating the same operation as above, the affected layer 27 formed on the side surface 41 of the second chip 33b is also cut. Furthermore, the side surfaces of the affected layer 27 formed on the side surfaces of all the chips 33 are cut, and the flow of the wafer processing method according to this embodiment is completed.

[0145] According to the present embodiment described above, when dividing the wafer 11 into chips 33, the laser beam 25 is used without cutting the wafer 11 with the cutting blade 116. Therefore, compared to dividing the wafer 11 into chips 33 by cutting with the cutting blade 116, it is possible to reduce material loss.

[0146] For example, when cutting a sapphire wafer 11 into pieces, the thickness of the cutting edge of the cutting blade needs to be about 0.3 mm. This corresponds to about twice the thickness of the cutting edge used when cutting a silicon wafer 11 (for example, 0.15 mm to 0.2 mm). If the thickness of the cutting edge is too thick, the width of the kerf (cut groove) will increase, resulting in increased material loss.

[0147] Furthermore, according to the above-described embodiment, when removing the affected layers 27 remaining on the side surfaces of the chips 33, the first tape 19 is expanded to widen the gaps 31 between the chips 33, and then the affected layers 27 formed on the side surfaces of the chips 33 are cut. More specifically, part of the cutting edge 118 is passed through the gaps 31, while another part of the cutting edge 118 is cut into the side surfaces of the chips 33. This reduces the amount of cutting into the chips 33 by the cutting edge 118 compared to when the gaps 31 are not widened. In other words, the affected layers 27 formed on the side surfaces of the chips 33 can be removed while minimizing material loss, allowing high-quality chips 33 to be manufactured.

[0148] For example, if the width of the altered layer 27 is 0.05 mm or more and 0.1 mm or less, if the gap between the chips 33 is about 0.1 mm, the altered layer 27 can be sufficiently removed by a cutting edge portion of normal thickness (for example, 0.15 mm or more and 0.2 mm or less).

[0149] Next, a second embodiment different from the first embodiment will be described. The wafer processing method according to the second embodiment includes the second tape application step S1, the grinding step S2, the affected layer formation step S3, the first tape application step S4, the second tape peeling step S5, and the gap formation step S6, as in the first embodiment. In the wafer processing method of the second embodiment, the cutting step S7 is performed in a manner different from that of the first embodiment.

[0150] 21 is a partial cross-sectional side view of the cutting blade 120, the wafer 11, and the first tape 19 in the cutting step S7 of the processing method for the wafer 11 according to the second embodiment. In the cutting step S7 of the first embodiment described above, the side surface (first side surface) 37 of the first chip 33a is cut, and then the side surface (second side surface) 39 of the second chip 33b is cut. In this embodiment, the side surface (first side surface) 37 of the first chip 33a and the side surface (second side surface) 39 of the second chip 33b are cut simultaneously.

[0151] That is, the cutting blade 120 has one first side surface 122a of the cutting edge portion 122 cut into the side surface (first side surface) 37 of the first tip 33a, and at the same time, the other side surface 122b cuts into the side surface (second side surface) 39 of the second tip 33b. The cutting blade 120 is configured so that it can simultaneously cut the affected layer 27 formed on the side surface (first side surface) 37 of the first tip 33a and the affected layer 27 formed on the side surface (second side surface) 39 of the second tip 33b.

[0152] According to the second embodiment, the affected layers 27 of the two adjacent chips 33a and 33b can be simultaneously cut and removed. Therefore, the number of steps in the cutting step S7 can be reduced compared to the first embodiment. As a result, the time required to process the wafer 11 can be reduced.

[0153] Next, a third embodiment will be described, which differs from the first and second embodiments described above. The wafer processing method according to the third embodiment, like the first and second embodiments, includes a second tape applying step S1, a grinding step S2, a modified layer forming step S3, a first tape applying step S4, a second tape peeling step S5, and a gap forming step S6. In the wafer processing method of the third embodiment, a cutting step S7 is performed in a manner different from that of the first and second embodiments.

[0154] 22 is a partial cross-sectional side view of the cutting blade 124, the wafer 11, and the first tape 19 in the cutting step S7 of the processing method for the wafer 11 according to the third embodiment. In this embodiment, a cutting blade 124 is used that includes a cutting edge portion 126 in which a first cutting edge portion 128, a second cutting edge portion 130, and a third cutting edge portion 132 disposed between the first cutting edge portion 128 and the second cutting edge portion 130 are stacked. The third cutting edge portion 132 is more likely to wear out than the first cutting edge portion 128. Furthermore, the third cutting edge portion 132 is more likely to wear out than the second cutting edge portion 130.

[0155] The wear susceptibility of the cutting edge portion can be adjusted, for example, by adjusting the density of the abrasive grains contained in the cutting edge portion, the average grain size of the abrasive grains, and the porosity of the cutting edge portion, or by changing the binder material. For example, if the density of the abrasive grains contained in the third cutting edge portion 132 is lower than the density of the abrasive grains in the first cutting edge portion 128 and the density of the abrasive grains in the second cutting edge portion 130, the third cutting edge portion 132 will be more susceptible to wear than the first cutting edge portion 128 and the second cutting edge portion 130.

[0156] Furthermore, for example, if the average particle size of the abrasive grains of the third cutting edge portion 132 is smaller than the average particle size of the abrasive grains of the first cutting edge portion 128 and the average particle size of the abrasive grains of the second cutting edge portion 130, the third cutting edge portion 132 will be more easily worn than the first cutting edge portion 128 and the second cutting edge portion 130. Furthermore, for example, if the porosity of the third cutting edge portion 132 is higher than the porosity of the first cutting edge portion 128 and the porosity of the second cutting edge portion 130, the third cutting edge portion 132 will be more easily worn than the first cutting edge portion 128 and the second cutting edge portion 130.

[0157] In this embodiment, similarly to the first embodiment, after the side surface (first side surface) 37 of the first tip 33a is cut, the side surface (second side surface) 39 of the second tip 33b is cut. That is, the first cutting edge portion 128 cuts into the side surface (first side surface) 37 of the first tip 33a, and then the second cutting edge portion 130 cuts into the side surface (second side surface) 39 of the second tip 33b.

[0158] Alternatively, in this embodiment, similarly to the second embodiment, the side surface (first side surface) 37 of the first tip 33a and the side surface (second side surface) 39 of the second tip 33b are cut simultaneously. That is, the first cutting edge portion 128 cuts into the side surface (first side surface) 37 of the first tip 33a, and at the same time, the second cutting edge portion 130 cuts into the side surface (second side surface) 39 of the second tip 33b.

[0159] In the cutting edge portion 126 of this embodiment, the third cutting edge portion 132, which does not cut into the first tip 33a or the second tip 33b, is configured to wear more easily than the first cutting edge portion 128, which cuts into the first tip 33a, and the second cutting edge portion 130, which cuts into the second tip 33b. This suppresses uneven wear of the cutting blade 124, allowing the wafer 11 to be cut appropriately.

[0160] As described above, according to the above-described embodiment of the present invention, the wafer 11 is irradiated with the laser beam 25 to form the affected layer 27, and cracks are formed starting from the affected layer 27 to divide the wafer 11. In this case, it is possible to reduce material loss compared to dividing the wafer 11 by cutting the wafer 11 with a cutting blade to form dividing grooves.

[0161] Furthermore, after dividing the wafer 11 to form a plurality of chips 33, the first tape 19 attached to the wafer 11 is expanded to form gaps 31 between the chips 33. Then, a cutting blade 116 is inserted into the gaps 31 and the side surfaces of the chips 33 are cut by the cutting blade 116. This allows the affected layer 27 exposed on the side surfaces of the chips 33 to be removed. Because no material originating from the wafer 11 is present in the gaps 31, no material is lost by inserting the cutting blade 116 into the gaps 31. Furthermore, even when the cutting blade 116 is used, the chips 33 can be cut by the minimum amount necessary to remove the affected layer 27, which also reduces material loss.

[0162] The structures, methods, and the like according to the above-described embodiments and modifications may be modified and implemented without departing from the scope of the present invention. [Explanation of symbols]

[0163] 11: Wafer 11a: 1st page 11b: 2nd side 11c: Notch 11d: Chamfered part 13: Planned division line 13a: Planned division line 13b: Planned division line 15: Device 17: Second tape (back grind tape) 19: First tape (dicing tape) 21: Frame 21a: Opening 23: Frame unit 25: Laser beam 27: Deteriorated layer 29: Crack 31: Gap 33: Chip 35: Side 37: Side 39: Side 41: Side 2a: Mounter device 2b: Mounter device 2c: Peeling device 4a: Holding table 4b: Holding table 4c: Holding table 6a: Frame 60a: recess 6b:Frame body 60b: recess 6c:Frame body 60c: Recess 8a: Holding plate 80a: Top surface (holding surface) 8b: Holding plate 80b:Top surface (holding surface) 8c: Holding plate 80c:Top surface (holding surface) 10a: Laura 10b: Laura 10c: Laura 12a: Support member 12b: Support member 20: Grinding equipment 22: Holding table 24:Frame body 24a: Recess 26: Holding plate 26a:Top surface (holding surface) 28: Grinding unit 30: Spindle 32: Grinding wheel 34: Grinding wheel 40: Laser irradiation device 42: Holding table 44:Frame body 46: Holding plate 48: Laser irradiation unit 50: Irradiation head 52: Camera 60: Splitting device (breaking device) 62: Holding table 64: Support member 66: Clamp 66: Movable clamp 68: Lower unit 70: Bar holding member 72: Lower pressure bar 74: Upper unit 76: Slider 78: Spacing adjustment member 80: Blade 82: Support member 84: Upper pressure bar 86: Damper 90: Expansion unit 92: Holding table 92a:Top surface 94: Clamp 96: Lifting unit 100: Cutting equipment 102: Holding table 104: Frame 106: Holding plate 108: Clamp 110: Cutting unit 112: Spindle 114: Spindle housing 116: Cutting blade 118: Cutting edge 118a: 1st side 118b:Second side 120: Cutting blade 122: Cutting edge 122a: 1st page 122b: 2nd side 124: Cutting blade 126: Cutting edge 126a: 1st page 126b: 2nd side 128: 1st cutting edge part 130:Second cutting edge part 132: 3rd cutting edge part

Claims

1. A wafer processing method for forming a plurality of chips from a wafer by dividing the wafer along planned dividing lines set on a surface of the wafer, comprising: a deteriorated layer forming step of forming an deteriorated layer along the planned dividing lines inside the wafer by irradiating the wafer along the planned dividing lines while focusing a laser beam having a wavelength that can pass through the wafer inside the wafer; a first tape adhering step of adhering a first tape to the back surface of the wafer after the affected layer forming step; a gap forming step of dividing the wafer into a plurality of chips by forming cracks in the wafer starting from the deteriorated layer after the first tape adhering step, and forming gaps between the plurality of chips by expanding the first tape; A wafer processing method comprising, after the gap forming step, a cutting step of inserting a cutting blade into the gap and cutting into the side surface of the chip, thereby cutting the side surface of the chip.

2. 2. The wafer processing method according to claim 1, wherein in the gap forming step, the crack is formed by pressing the wafer before expanding the first tape.

3. In the gap forming step, the gap is formed between a first side surface of a first chip and a second side surface of a second chip adjacent to the first chip, the second side surface facing the first side surface; 2. The wafer processing method of claim 1, wherein in the cutting step, the cutting blade has a first annular surface and a second annular surface opposite the first surface, and the first surface side of the cutting blade is caused to cut into the first side surface and the second surface side of the cutting blade is caused to cut into the second side surface, thereby simultaneously cutting the first side surface side of the first chip and the second side surface side of the second chip.

4. The cutting blade has a structure in which a first cutting edge portion having the first surface, a second cutting edge portion having the second surface, and a third cutting edge portion disposed between the first cutting edge portion and the second cutting edge portion are stacked, The third cutting edge portion is more easily worn than the first cutting edge portion, The third cutting edge portion is more easily worn than the second cutting edge portion, 4. The wafer processing method according to claim 3, wherein in the cutting step, the first side surface of the first chip is cut by the first cutting blade portion, and the second side surface of the second chip is cut by the second cutting blade portion.

5. a second tape adhering step of adhering a second tape to the surface of the wafer before the affected layer forming step; a second tape peeling step of peeling off the second tape attached to the surface of the wafer after the affected layer forming step and before the cutting step, In the affected layer forming step, the laser beam is irradiated onto the wafer from the back surface side of the wafer; 5. The wafer processing method according to claim 1, wherein in the cutting step, the cutting blade is inserted into the gap from the front surface side of the wafer.

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