Method of processing a wafer

Abstract

A wafer processing method is provided, which does not hinder the joining performed later even after the head of the protrusion-shaped electrode is cut. A wafer processing method, which is a wafer divided by a division predetermined line on a front surface to form a plurality of devices having a protrusion-shaped electrode, wherein the wafer processing method includes: a cutting step of holding a back surface of the wafer by a holding surface of a chuck table, cutting the head of the protrusion-shaped electrode to make the height of the head uniform by a cutter rotating in parallel with the holding surface, and making a metal surface exposed; a thermocompression bonding tab laying step of laying a thermocompression bonding tab on the front surface of the wafer; a thermocompression bonding step of heating and pressing the thermocompression bonding tab to perform thermocompression bonding; and a peeling step of peeling the thermocompression bonding tab from the wafer before the wafer is divided into each device chip and the electrode is joined to a wiring substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to a wafer processing method for a wafer having a plurality of devices with protrusion-shaped electrodes formed on a front surface divided by a division predetermined line. BACKGROUND

[0002] After the back surface of the wafer having a plurality of devices of IC, LSI, etc. formed on a front surface divided by a division predetermined line is ground to a prescribed thickness by a grinding device, the wafer is divided into individual device chips by a dicing device, a laser processing device, etc., and the device chips are used for electronic equipment such as mobile phones, personal computers, etc.

[0003] Further, in the case of a wafer having a plurality of devices with protrusion-shaped electrodes formed on a front surface divided by a division predetermined line, in order to make the height of the head (top) of the electrodes uniform and remove the surface oxide film and dirt, the wafer is transported to a cutting device, the back surface of the wafer is held on a holding surface of a chuck table, and the head of the protrusion-shaped electrode (bump) is cut by a tool rotating in parallel with the holding surface (see, for example, Patent Document 1).

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-319697

[0005] As described above, although the wafer in which the head of the protrusion-shaped electrode is cut so that the height is made uniform and the metal surface is exposed is in a state suitable for bonding by being transported to the cutting device, it is not necessary to divide the wafer into individual device chips immediately after the head of the electrode is cut and perform the bonding process. With the passage of time, an oxide film is formed on the metal surface of the electrode, and dirt is attached depending on the storage conditions, which can hinder the bonding of the subsequent process. SUMMARY

[0006] The present application was achieved in view of the above-described facts, and has an object to provide a wafer processing method in which the bonding performed later is not hindered even after the head of the protrusion-shaped electrode is cut.

[0007] According to one aspect of the present application, there is provided a wafer processing method for a wafer having a plurality of devices with protrusion-shaped electrodes formed on a front surface divided by a division predetermined line, wherein the wafer processing method includes: a cutting step of holding the back surface of the wafer by a holding surface of a chuck table and cutting the head of the protrusion-shaped electrode to make the height of the head uniform and expose a metal surface by a tool rotating in parallel with the holding surface; a thermocompression bonding tab attaching step of attaching a thermocompression bonding tab to the front surface of the wafer; a thermocompression bonding step of heating and pressing the thermocompression bonding tab to perform thermocompression bonding; and a peeling step of peeling the thermocompression bonding tab before the wafer is divided into individual device chips and the electrode is bonded to a wiring substrate.

[0008] In one aspect of the present application, it is preferable that the wafer processing method includes a plating step of forming a plating layer on the metal surface of the head of the electrode after the cutting step and before the thermocompression bonding step.

[0009] In one aspect of the present application, it is preferable that the thermocompression bonding sheet is a polyolefin-based sheet or a polyester-based sheet. It is preferable that the polyolefin-based sheet is any one of a polyethylene sheet, a polypropylene sheet, a polystyrene sheet, and the polyester-based sheet is any one of a polyethylene terephthalate sheet, a polyethylene naphthalate sheet. Further, it is preferable that, with respect to the heating temperature at the time of heating the thermocompression bonding sheet in the thermocompression bonding step, 120°C to 140°C in the case where the polyethylene sheet is selected as the thermocompression bonding sheet, 160°C to 180°C in the case where the polypropylene sheet is selected, 220°C to 240°C in the case where the polystyrene sheet is selected, 250°C to 270°C in the case where the polyethylene terephthalate sheet is selected, and 160°C to 180°C in the case where the polyethylene naphthalate sheet is selected.

[0010] According to the wafer processing method of one aspect of the present application, the electrode is shut off from the outside air during the period after the head of the electrode is cut and before the wafer is divided into individual device chips and joined, and thus the metal surface of the electrode is not oxidized or contaminated, so that the joining is not easily hindered. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a general perspective view of a cutting device suitable for implementing the cutting step of the present embodiment.

[0012] Figure 2 (a) of is a plan view showing an embodiment of the cutting step, Figure 2 (b) of is a partial enlarged sectional view of the wafer, Figure 2 (c) of is a plan view of the wafer after the cutting step, Figure 2 (d) of is a partial enlarged sectional view of the wafer after the cutting step.

[0013] Figure 3 (a) and Figure 3 (b) of is a perspective view showing an embodiment of the thermocompression bonding sheet laying step.

[0014] Figure 4 (a) of is a perspective view showing an embodiment of the thermocompression bonding step, Figure 4 (b) of Figure 4 (a) of is a partial enlarged sectional view of the wafer, Figure 4 (c) of Figure 4 (b) is a partial enlarged sectional view of another embodiment of (b).

[0015] Figure 5 is a perspective view showing an embodiment of the outer periphery removing step.

[0016] Figure 6 is a perspective view showing an embodiment of the back surface grinding step.

[0017] Figure 7 (a) of FIG. 1 is a perspective view showing an embodiment of the peeling step, Figure 7 (b) of FIG. 1 is a perspective view showing an embodiment of the dividing step.

[0018] Explanation of Reference Numerals

[0019] 1: cutting device; 2: device housing; 21: main portion; 22: upright wall; 3: cutting unit; 31: moving base; 312: guide rail; 32: spindle unit; 322: rotating spindle; 323: servo motor; 324: tool tool mounting member; 33: tool tool; 331: cutter; 4: cutting feed mechanism; 41: external screw rod; 44: pulse motor; 5: chuck table mechanism; 52: chuck table; 52a: suction chuck; 10: wafer; 12: device; 120: electrode; 122: metal surface; 14: division predetermined line; 16: underfill material; 60: thermocompression tab; 70: thermocompression bonding device; 72: suction table; 74: suction chuck; 80: thermocompression bonding member; 82: rotating shaft; 84: heating roller; 90: cutting member; 96: cutting tool; 100: grinding device; 104: grinding wheel; 106: grinding tool; 110: chuck table; 130: division groove; 140: cutting device; 146: cutting tool. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of a wafer processing method according to the present application will be described in detail with reference to the drawings.

[0021] Figure 1 A perspective view of a cutting device 1 suitable for implementing the cutting step of the present embodiment is shown. The cutting device 1 has a device housing 2. The device housing 2 has a main portion 21 which is substantially rectangular parallelepiped in shape, and an upright wall 22 which is provided to a rear end portion (upper right end in the drawing) of the main portion 21 and extends substantially vertically upward. A pair of guide rails 312 which extend in the vertical direction are provided to a front surface of the upright wall 22. A cutting unit 3 which is a cutting member is installed on the pair of guide rails 312 in a manner so as to be movable in the vertical direction. Figure 1

[0022] ​The cutting unit 3 has a movable base 31 and a spindle unit 32 mounted to the movable base 31. The movable base 31 is formed with a guided groove that is engaged with the pair of rails 312 in a slidable manner. The movable base 31 is mounted to the pair of rails 312 provided to the upright wall 22 in a slidable manner, a support member 313 is mounted to a front surface of the movable base 31, and the spindle unit 32 is mounted to the support member 313.

[0023] The spindle unit 32 has a spindle housing 321 mounted to the support member 313, a rotary spindle 322 provided to the spindle housing 321 in a rotatable manner, and a servo motor 323 as a drive source that rotationally drives the rotary spindle 322. A lower end portion of the rotary spindle 322 protrudes downward beyond a lower end of the spindle housing 321, and a circular plate-shaped tool tool mounting member 324 is provided to the lower end portion.

[0024] A tool mounting hole 324a that penetrates in the up-and-down direction is provided to a portion of the outer peripheral portion of the tool tool mounting member 324 that is distal from the rotation axis core. A tool 331 that constitutes the tool tool 33 is inserted into the tool mounting hole 324a, and is fastened and fixed by a stud bolt 330 that is screwed into a tapped hole formed to the side of the tool tool mounting member 324. In the illustrated embodiment, the tool 331 is formed in a rod shape from tool steel such as super steel, and has a cutting edge formed from diamond or the like at a lower front end portion thereof. The tool tool 33 that is thus constituted and mounted to the tool tool mounting member 324 is rotated by the rotary spindle 322 described above, and rotates together with the tool tool mounting member 324 in the direction indicated by the arrow R1.

[0025] The illustrated cutting apparatus 1 has a cut-in feed mechanism 4 that moves the cutting unit 3 in the up-and-down direction (the direction indicated by the arrow Z) along the pair of rails 312. The cut-in feed mechanism 4 has an externally threaded rod 41 that is provided to the front side of the upright wall 22 and extends substantially vertically. The upper end portion and the lower end portion of the externally threaded rod 41 are supported by bearing members provided to the upright wall 22 in a rotatable manner. A pulse motor 44 as a drive source that rotationally drives the externally threaded rod 41 fixed to the upright wall 22 is provided to the upper end portion of the externally threaded rod 41, and the output shaft of the pulse motor 44 is coupled to the externally threaded rod 41. A coupling portion (not shown) that protrudes rearward from the widthwise central portion is also formed to the rear surface of the movable base 31, and the externally threaded rod 41 is screwed into a tapped hole formed to the coupling portion. Therefore, when the pulse motor 44 is rotated in the forward direction, the cutting unit 3 descends together with the movable base 31, and when the pulse motor 44 is rotated in the reverse direction, the cutting unit 3 ascends together with the movable base 31.

[0026] A chuck stage mechanism 5 is disposed on the upper surface of the main portion 21 of the housing 2. The chuck stage mechanism 5 includes a rotatably disposed circular plate-shaped chuck stage 52. On the upper surface of the chuck stage 52, a holding surface is formed by an air-permeable suction chuck 52a. This holding surface is connected to a suction source (not shown), and negative pressure is applied to the holding surface by actuating the suction source. The chuck stage mechanism 5 has a moving mechanism (not shown) housed inside the main portion 21, which allows the chuck stage 52 and the cover member 54 to move together in the direction indicated by arrow X1, enabling the chuck stage 52 to... Figure 1 The workpiece positioned in the center moves back and forth between the workpiece loading / unloading area and the machining area below the spindle unit 32.

[0027] Figure 1 The cutting device 1 shown is configured as described above. Hereinafter, the cutting process in the wafer processing method of this embodiment implemented using the cutting device 1 described above will be described.

[0028] For example, Figure 1 As shown, the workpiece in this embodiment is a semiconductor wafer 10 divided by a predetermined dividing line 14, on which a plurality of devices 12 are formed. As shown in the upper part of the figure, a portion of the wafer 10 is enlarged, and a plurality of protruding electrodes 120 are formed on the devices 12.

[0029] exist Figure 2 (a) shows, in a top view, the wafer 10 and the tool mounting component 324 in a state of being attracted and held on a chuck table 52 located in the workpiece loading / unloading area before cutting is performed. Figure 2 (b) shows a partially enlarged cross-sectional view of wafer 10. Figure 2 As shown in (b), the front side of the wafer 10 on which each device 12 is formed is covered with a bottom filler material 16 formed of synthetic resin, so that protruding electrodes 120 formed on the device 12 are embedded.

[0030] If the chip 10 is attracted and held on the chuck stage 52, then according to Figure 1 The servo motor 323 of the spindle unit 32 is driven to rotate the tool mounting component 324 in the direction indicated by arrow R1, and to actuate the feed mechanism 4 to descend to a predetermined height for cutting the underfill material 16 and a portion of the head of the electrode 120 on the wafer 10. A moving member (not shown) is actuated to move the chuck table mechanism 5 towards... Figure 2(a) is moved in the direction of the arrow X1, the chuck table 52 holding the wafer 10 passes through the machining area below the tool tool mounting member 324. In this way, the chuck table 52 holding the wafer 10 passes through the machining area, so that the wafer 10 is moved in the direction of the arrow X1 as shown in Figure 2 (c), the wafer 10 is cut by the tool 331 rotating in parallel with the holding surface of the chuck table 52. As a result, as shown in Figure 2 (d), the heads of the protrusion-shaped electrodes 120 are formed into a uniform height to form the metal surface 122, and the front surface of the bottom filler material 16 is exposed at the same time. Thus, the cutting process is completed.

[0031] As described above, after the cutting process is implemented, the thermocompression bonding tab laying process is implemented next. Hereinafter, the thermocompression bonding tab laying process will be described with reference to Figure 3 (a) and Figure 3 (b).

[0032] In implementing the thermocompression bonding tab laying process, the wafer 10 on which cutting machining has been implemented by the cutting process is carried to Figure 3 (a) shows a thermocompression bonding device 70 (only a part is shown) to which the wafer 10 is carried. The thermocompression bonding device 70 has a suction table 72, and a suction chuck 74 having air permeability is formed on the upper surface of the suction table 72. The wafer 10 carried to the thermocompression bonding device 70 is placed on the center of the suction chuck 74 with the back surface 10b side facing downward. Next, as shown in Figure 3 (b), the thermocompression bonding tab 60 is laid from above so as to cover at least the entire suction chuck 74. In addition, the thermocompression bonding tab 60 is set to a size that is at least larger than the outer diameter of the suction chuck 74, and preferably, as shown in Figure 3 (a) and Figure 3 (b), a size that is slightly smaller than the outer diameter of the chuck table 72.

[0033] The thermocompression bonding tab 60 is preferably a polyolefin-based tab or a polyester-based tab. In the case of using a polyolefin-based tab, it is preferable to select any one of a polyethylene (PE) tab, a polypropylene (PP) tab, and a polystyrene (PS) tab, and in the case of using a polyester-based tab, it is preferable to select any one of a polyethylene terephthalate (PET) tab and a polyethylene naphthalate (PEN) tab. In the present embodiment, a polyethylene tab is selected as the thermocompression bonding tab 60. In addition, no paste layer is formed on the sticking surface of the thermocompression bonding tab 60 opposite to the wafer 10. Thus, the thermocompression bonding tab laying process is completed.

[0034] As described above, after the thermocompression bonding tab laying process is implemented, the thermocompression bonding process is implemented next. Hereinafter, the thermocompression bonding process will be described with reference to Figure 4 As described above, after the thermocompression bonding tab laying process is implemented, the thermocompression bonding process is implemented next. Hereinafter, the thermocompression bonding process will be described with reference to

[0035] As described above, if the thermocompression bonding sheet 60 is laid on the suction table 72, an unillustrated suction source is activated to apply a negative pressure Vm to the suction table 72, and the wafer 10 and the thermocompression bonding sheet 60 placed on the chuck 74 are sucked. Next, as shown in (a) of Fig. 10, a thermocompression bonding member 80 (only a part is shown) is positioned on the thermocompression bonding sheet 60. The thermocompression bonding member 80 has a heating roller 84 held so as to be rotatable about a rotational axis 82 in the direction shown by an arrow R2. Fluorine resin is coated on the surface of the heating roller 84 so as not to adhere to the heating roller 84 even if the thermocompression bonding sheet 60 is heated to exhibit adhesion. An electric heater and a temperature sensor (omitted from illustration) are built in the inside of the heating roller 84, and the surface of the heating roller 84 is adjusted to a desired temperature by a control device prepared separately. Figure 4 As described above, if the thermocompression bonding sheet 60 is laid on the suction table 72, an unillustrated suction source is activated to apply a negative pressure Vm to the suction table 72, and the wafer 10 and the thermocompression bonding sheet 60 placed on the chuck 74 are sucked. Next, as shown in (a) of Fig. 10, a thermocompression bonding member 80 (only a part is shown) is positioned on the thermocompression bonding sheet 60. The thermocompression bonding member 80 has a heating roller 84 held so as to be rotatable about a rotational axis 82 in the direction shown by an arrow R2. Fluorine resin is coated on the surface of the heating roller 84 so as not to adhere to the heating roller 84 even if the thermocompression bonding sheet 60 is heated to exhibit adhesion. An electric heater and a temperature sensor (omitted from illustration) are built in the inside of the heating roller 84, and the surface of the heating roller 84 is adjusted to a desired temperature by a control device prepared separately.

[0036] If the thermocompression bonding member 80 is positioned on the thermocompression bonding sheet 60, the thermocompression bonding sheet 60 is heated and pressed by the heating roller 84. As shown in (a) of Fig. 11, the heating roller 84 is rotated in the direction shown by the arrow R2 while being moved along the front surface of the thermocompression bonding sheet 60 in the direction shown by an arrow R3. The heating temperature of the thermocompression bonding sheet 60 when heated by the heating roller 84 is set in the range of 120°C to 140°C. The heating temperature is a temperature in the vicinity of the melting point of the polyethylene sheet constituting the thermocompression bonding sheet 40, and is a temperature at which the thermocompression bonding sheet 60 does not excessively melt and can be softened to exhibit adhesion. When the thermocompression bonding sheet 60 is pressed, as described above, the negative pressure Vm is applied to the chuck 74 via the suction table 72, and air remaining between the front surface 10a of the wafer 10 and the thermocompression bonding sheet 60 is completely sucked and removed, as shown in (b) of Fig. 11. As a result, the thermocompression bonding sheet 60 is firmly bonded to the wafer 10. Figure 4 Figure 4 As described above, if the thermocompression bonding sheet 60 is laid on the suction table 72, an unillustrated suction source is activated to apply a negative pressure Vm to the suction table 72, and the wafer 10 and the thermocompression bonding sheet 60 placed on the chuck 74 are sucked. Next, as shown in (a) of Fig. 10, a thermocompression bonding member 80 (only a part is shown) is positioned on the thermocompression bonding sheet 60. The thermocompression bonding member 80 has a heating roller 84 held so as to be rotatable about a rotational axis 82 in the direction shown by an arrow R2. Fluorine resin is coated on the surface of the heating roller 84 so as not to adhere to the heating roller 84 even if the thermocompression bonding sheet 60 is heated to exhibit adhesion. An electric heater and a temperature sensor (omitted from illustration) are built in the inside of the heating roller 84, and the surface of the heating roller 84 is adjusted to a desired temperature by a control device prepared separately.

[0037] In the present embodiment, the thermocompression bonding sheet 60 is thermocompression-bonded to the wafer 10, whereby the metal surface 122 of the protrusion-shaped electrode 120 formed in the device 12 is prevented from directly contacting the outside air, and the formation of an oxide film on the metal surface 122 of the electrode 120 is suppressed during the period until the thermocompression bonding sheet 60 is peeled. Further, by thermocompression-bonding the thermocompression bonding sheet 60, direct adhesion of dirt to the metal surface 122 of the electrode 120 of the device 12 is also prevented.

[0038] Further, the present application is not limited to the above-described embodiment, and for example, it can be that, at any timing after the cutting process and before the thermocompression bonding process, as shown in (a) of Fig. 12, the thermocompression bonding member 80 is positioned on the thermocompression bonding sheet 60. The thermocompression bonding member 80 is moved along the front surface of the thermocompression bonding sheet 60 in the direction shown by an arrow R3 while being rotated in the direction shown by an arrow R2. The heating temperature of the thermocompression bonding sheet 60 when heated by the heating roller 84 is set in the range of 120°C to 140°C. The heating temperature is a temperature in the vicinity of the melting point of the polyethylene sheet constituting the thermocompression bonding sheet 40, and is a temperature at which the thermocompression bonding sheet 60 does not excessively melt and can be softened to exhibit adhesion. When the thermocompression bonding sheet 60 is pressed, as described above, the negative pressure Vm is applied to the chuck 74 via the suction table 72, and air remaining between the front surface 10a of the wafer 10 and the thermocompression bonding sheet 60 is completely sucked and removed, as shown in (b) of Fig. 12. As a result, the thermocompression bonding sheet 60 is firmly bonded to the wafer 10. Figure 4 ​As shown in (c), a plating process (e.g., electroplating) is performed on the metal surface 122 of each electrode 120 after cutting to form a plating layer 18. As a result, when additional bonding is performed, a circuit is reliably formed between the electrode and the wiring substrate, thereby further suppressing the bonding from being hindered.

[0039] After performing the above-mentioned hot pressing process, it is preferable to use... Figure 5 As shown, a peripheral removal process is performed to remove the outer peripheral region 60a of the thermoplastic tab 60 protruding from the wafer 10. This peripheral removal process is performed, for example, using the cutting member 90 shown in the figure (only a portion is shown). The cutting member 90 has a spindle unit 92, a rotating spindle 94 supported by the spindle unit 92, and a disc-shaped cutting tool 96 mounted at the front end of the rotating spindle 94. A drive motor (not shown) is provided at the rear end of the spindle unit 92, which, together with the rotating spindle 94, drives the cutting tool 96 to rotate at a desired speed in the direction indicated by arrow R4.

[0040] In order to implement the peripheral removal process, such as Figure 5 As shown, the suction stage 72 is positioned below the cutting member 90. On the thermoforming tab 60, the cutting tool 96 is positioned at the boundary between the outer peripheral region and the inner region extending outward from the wafer 10. The cutting tool 96 is rotated in the direction of arrow R4 and fed from above according to the thickness of the thermoforming tab 60. The suction stage 72 is rotated in the direction indicated by arrow R5, forming a cutting groove 62 (indicated by thick lines) along the outer periphery of the wafer 10. After the cutting groove 62 is formed along the entire circumference of the wafer 10, the outer peripheral region of the thermoforming tab 60 is cut away from the inner region and removed. If the outer peripheral region of the thermoforming tab 60 is removed, the suction source (not shown) that applies a negative pressure Vm to the suction stage 72 is stopped. The result is as follows: Figure 5 As shown, the wafer 10, which is integrated with the thermo-pressing tab 60, is removed from the thermo-pressing device 70.

[0041] As described above, if a hot-pressing process and a peripheral removal process are performed as needed, a back-side grinding process can also be performed to process the wafer 10 integrated with the hot-pressing tab 60 to the desired thickness. To perform the back-side grinding process, such as... Figure 6 As shown, the wafer 10, which is integrated with the hot-pressed tab 60, is transported to the grinding apparatus 100.

[0042] Moved to Figure 6The wafer 10 of the shown grinding device 100 (only a part is shown) is placed on a chuck table 110 of the grinding device 100 in a manner that the hot-pressing tab 60 side adhered to the front surface 10a side is made lower. An adsorbing surface having aeration property connected to an unshown suction member is provided on the upper surface of the chuck table 110, and the wafer 10 is suction-held on the chuck table 110 by making the suction member operate. The grinding device 100 has, in addition to the chuck table 110, a wheel mounting seat 102 that rotates by an unshown motor, a grinding wheel 104 mounted to the lower surface of the wheel mounting seat 102, and a plurality of grinding tools 106 provided in a ring shape on the lower surface of the grinding wheel 104.

[0043] After the wafer 10 is suction-held on the chuck table 110, as shown in Figure 6 , the grinding wheel 102 is made to rotate in the direction shown by an arrow R6 at a speed of, for example, 6000 rpm, the chuck table 110 is made to rotate in the direction shown by an arrow R7 at a speed of, for example, 300 rpm, and at the same time, an unshown grinding feed member is made to operate, and the grinding tools 106 are made to contact from above the back surface 10b of the wafer 10 and are made to grind in the direction shown by an arrow Z1 at a grinding feed speed of, for example, 1 μm / sec. At this time, the grinding is performed while the thickness of the wafer 10 is measured by an unshown measuring instrument, and the wafer 10 is ground to a desired thickness. Thus, the back surface grinding process is completed. In addition, in the present embodiment, as described above, the hot-pressing tab 60 is adhered in advance to the front surface 10a of the wafer 10, and the face to which the hot-pressing tab 60 is adhered is placed and suction-held on the chuck table 110, and therefore, it is not necessary to re-adhere a protective tape or the like when the above-described back surface grinding process is performed.

[0044] As described above, after the wafer 10 and the hot-pressing tab 60 are integrated, the device 12 formed on the wafer 10 is divided into individual device chips and is bonded on a prescribed wiring substrate. Therefore, before the electrode 120 of the device 12 is bonded to the wiring substrate, a division process for dividing the wafer 10 into individual device chips is performed.

[0045] When the division process is performed, as shown in Figure 7 (a), a ring-shaped frame F is prepared, the front surface 10a side of the wafer 10 is positioned in the center of an opening portion capable of accommodating the wafer 10 with the front surface 10a side facing upward, and the wafer 10 is adhered to an adhesive tape T and is held to the frame F. Thus, after the wafer 10 is held to the frame F by the adhesive tape T, as shown in Figure 7 (a), the hot-pressing tab 60 is peeled off. After the hot-pressing tab 60 is peeled off from the front surface 10a of the wafer 10, the wafer 10 is conveyed to Figure 7The cutting device 140 (only a part is shown) shown in (b).

[0046] The cutting device 140 has a chuck table, which is omitted from the illustration, and has a spindle unit 142. The spindle unit 142 supports a rotary spindle 144 so as to be rotatable, and a disc-shaped cutting tool 146 is attached to the front end of the rotary spindle 144. A drive motor, which is not shown, is attached to the rear end of the spindle unit 142, and the cutting tool 146 is driven to rotate at a desired rotational speed in the direction shown by an arrow R8 together with the rotary spindle 144. The chuck table is configured to be movable in the X-axis direction shown by an arrow X by a movement member, which is not shown, and the spindle unit 142 is configured to be movable in the Y-axis direction shown by an arrow Y, which is perpendicular to the X-axis direction, and in the up-and-down direction, which is perpendicular to the X-axis direction and the Y-axis direction, by a movement member, which is not shown.

[0047] The wafer 10 and the frame F, which are carried to the cutting device 140, are placed and held on the chuck table, and the cutting position (the division predetermined line 14) of the wafer 10 is detected (aligned) by an alignment member, which is not shown. Based on the position information obtained by implementing the alignment, the front end of the cutting tool 146 is positioned at a prescribed machining start position and at a depth at which the wafer 10 is to be cut. After the cutting tool 146 is positioned at the machining start position, the chuck table, which holds the wafer 10, is moved in the X-axis direction in such a manner as to follow the division predetermined line 14 of the wafer 10, and a division groove 130 for dividing the wafer 10 into individual devices is formed. Further, the spindle unit 142 is appropriately indexed fed in the Y-axis direction while the division groove 130 is formed along the remaining division predetermined line 14 parallel to the prescribed direction. Then, after the division groove 130 is formed along all of the division predetermined lines 14 in the prescribed direction, the chuck table is rotated by 90 degrees, and the division groove 130 for cutting the wafer 10 is formed along all of the division predetermined lines 14 formed in a direction perpendicular to the prescribed direction. As a result, the plurality of devices 12 formed in the wafer 10 are divided into individual devices from the wafer 10 to become device chips. The devices 12, which have become individual device chips, are carried to a bonding process and are appropriately bonded to a wiring substrate.

[0048] According to the present embodiment, the heat staking piece 60 is heat staked to the front surface 10a of the wafer 10 during the period before the wafer 10 is divided into individual device chips and bonded to the wiring substrate, and therefore the metal surface 122 of the electrode 120 exposed on the device 12 is isolated from the outside air. Therefore, an oxide film is not formed on the metal surface 122 of the electrode 120 or the metal surface 122 is not contaminated, and bonding is prevented from being impeded. Further, when bonding is implemented, the heat staking piece 60 is peeled from the wafer 10, and therefore even if burrs remain on the electrode 120 of the device 12, the burrs are removed together with the heat staking piece 60.

[0049] In addition, in the above embodiment, the heat staking piece 60 is peeled from the front surface 10a of the wafer 10 when the dividing process is performed, but in a case where the divided device chips are not immediately bonded to the wiring substrate after the dividing process is performed and there is time before the bonding is performed, the device 12 can be divided into individual device chips with the heat staking piece 60 adhered to the wafer 10, and then the heat staking piece 60 is peeled from the device chips when the device chips are bonded to the wiring substrate.

[0050] In addition, in the above embodiment, the heat staking piece 60 is a polyethylene sheet, but the present application is not limited thereto and can be appropriately selected from polyolefin-based sheets or polyester-based sheets.

[0051] In a case where a polypropylene sheet is selected as the heat staking piece 60, the heating temperature when the above heat staking process is performed is preferably set to 160°C to 180°C. In addition, in a case where a polystyrene sheet is selected as the heat staking piece 60, the heating temperature when the heat staking process is performed is preferably set to 220°C to 240°C.

[0052] In a case where a polypropylene sheet is selected as the heat staking piece 60, the heating temperature when the above heat staking process is performed is preferably set to 160°C to 180°C. In addition, in a case where a polystyrene sheet is selected as the heat staking piece 60, the heating temperature when the heat staking process is performed is preferably set to 220°C to 240°C.

[0053] In addition, in the above embodiment, the heat staking piece 60 is a polyethylene sheet, but the present application is not limited thereto and can be appropriately selected from polyolefin-based sheets or polyester-based sheets.

[0054] In a case where a polypropylene sheet is selected as the heat staking piece 60, the heating temperature when the above heat staking process is performed is preferably set to 160°C to 180°C. In addition, in a case where a polystyrene sheet is selected as the heat staking piece 60, the heating temperature when the heat staking process is performed is preferably set to 220°C to 240°C.

Claims

1. A wafer processing method, the wafer being divided by a division predetermined line on a front surface to form a plurality of devices having protrusion-shaped electrodes, the wafer being covered with an underfill material made of synthetic resin on the front surface to become a state where the electrodes are buried, wherein the wafer processing method comprises the following steps: a cutting step of holding a back surface of the wafer with a holding surface of a chuck table, cutting a part of a head of the protrusion-shaped electrode together with the underfill material to make the height of the head uniform to form a flat surface, and making a metal surface exposed from the underfill material, using a cutter that rotates in parallel with the holding surface; a thermocompression sheet laying step of laying a thermocompression sheet on the front surface of the wafer; a thermocompression step of thermocompressing the thermocompression sheet by heating and pressing the thermocompression sheet; and a peeling step of peeling the thermocompression sheet before the wafer is divided into individual device chips, and then dividing into individual device chips to join the electrodes to a wiring substrate.

2. The wafer processing method according to claim 1, wherein the wafer processing method comprises a plating step of forming a plating layer on the metal surface of the head of the electrode after the cutting step and before the thermocompression step is performed.

3. The wafer processing method according to claim 1 or 2, wherein the thermocompression sheet is a polyolefin sheet or a polyester sheet.

4. The wafer processing method according to claim 1 or 2, wherein the thermocompression sheet is a polyethylene sheet, and a heating temperature when the thermocompression sheet is heated in the thermocompression step is 120°C to 140°C.

5. The wafer processing method according to claim 1 or 2, wherein the thermocompression sheet is a polypropylene sheet, and a heating temperature when the thermocompression sheet is heated in the thermocompression step is 160°C to 180°C.

6. The wafer processing method according to claim 1 or 2, wherein the thermocompression sheet is a polystyrene sheet, and a heating temperature when the thermocompression sheet is heated in the thermocompression step is 220°C to 240°C.

7. The wafer processing method according to claim 1 or 2, wherein the thermocompression sheet is a polyethylene terephthalate sheet, and a heating temperature when the thermocompression sheet is heated in the thermocompression step is 250°C to 270°C.

8. The wafer processing method according to claim 1 or 2, wherein the thermocompression sheet is a polyethylene naphthalate sheet, and a heating temperature when the thermocompression sheet is heated in the thermocompression step is 160°C to 180°C. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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