Wafer processing method

Abstract

To provide a wafer processing method in which cutting waste does not adhere to the surface of a device chip and a part of an adhesive layer does not remain.SOLUTION: A wafer processing method includes: a thermocompression sheet disposing step of arranging a thermocompression sheet T1 on a surface 10a of a wafer 10; a thermocompression bonding step of heating the thermocompression bonding sheet T1 and bonding it to the surface 10a of the wafer 10; a dicing tape supporting step of supporting a back surface 10b of the wafer 10 with a dicing tape T2; a thermocompression sheet removing step of cutting and removing the thermocompression sheet T1 along a scheduled dividing line 14 by cutting means 42 having a rotatable cutting blade 45; and a dividing step of dividing the wafer 10 into individual device chips 12' along the scheduled dividing line 14 by the cutting means 42 having a rotatable cutting blade 48.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a method for processing a wafer to divide the wafer into individual device chips.

Background Art

[0002] A wafer on which a plurality of devices such as ICs and LSIs are formed on a surface partitioned by a dicing line is divided into individual device chips by a dicing apparatus having a rotatable cutting blade, and is used in electric devices such as mobile phones and personal computers.

[0003] In addition, when a wafer formed by partitioning a plurality of devices including lenses on the surface of a gallium arsenide (GaAs) semiconductor substrate by a dicing line is divided into individual device chips by a dicing apparatus, there is a problem that cutting chips adhere around the lenses constituting the devices, deteriorating the quality of the devices.

[0004] Therefore, it is conceivable to cut by sticking an adhesive tape on the surface of the wafer and divide it into individual device chips (see, for example, Patent Document 1). However, although the adhesion of cutting chips to the surface of the wafer can be suppressed by sticking the adhesive tape on the surface of the wafer, when the adhesive tape is peeled off from the device chip, a part of the adhesive layer adheres to the device and remains, causing a problem of deteriorating the quality of the device chip.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above facts, and its main technical problem is to provide a method for processing a wafer in which even when a wafer having a plurality of devices partitioned by division planned lines and formed on its surface is divided into individual device chips, cutting chips do not adhere to the surface of the device chips and no part of the adhesive layer remains.

Means for Solving the Problems

[0007] In order to solve the above main technical problem, according to the present invention, there is provided a method for processing a wafer in which a wafer having a plurality of devices partitioned by division planned lines and formed on its surface is divided into individual device chips, the method including: a thermocompression bonding sheet disposing step of disposing a thermocompression bonding sheet on the surface of the wafer; a thermocompression bonding step of heating the thermocompression bonding sheet and pressing it onto the surface of the wafer; a dicing tape supporting step of supporting the back surface of the wafer with a dicing tape; a thermocompression bonding sheet removing step of cutting and removing the thermocompression bonding sheet along the division planned line by cutting means rotatably provided with a cutting blade; and a dividing step of dividing the wafer into individual device chips along the division planned line by cutting means rotatably provided with a cutting blade. When removing the thermocompression bonding sheet by cutting along the planned division line in the thermocompression bonding sheet removal step, the thermocompression bonding sheet is cut and removed within a range where the cutting blade does not reach the wafer. A method for processing a wafer is provided.

[0008] The The thickness of the cutting blade used in the thermocompression bonding sheet removing step is preferably thicker than the thickness of the cutting blade used in the dividing step. Further, the abrasive grains constituting the cutting blade used in the thermocompression bonding sheet removing step are preferably coarser than the abrasive grains constituting the cutting blade used in the dividing step.

[0009] The thermocompression bonding sheet is a polyolefin-based sheet or a polyester-based sheet. The polyolefin-based sheet is any one of a polyethylene sheet, a polypropylene sheet, and a polystyrene sheet, and the polyester-based sheet is preferably any one of a polyethylene terephthalate sheet and a polyethylene naphthalate sheet. When the thermocompression bonding sheet is heated and pressed onto the surface of the wafer, the heating temperature is 120°C to 140°C when a polyethylene sheet is selected as the thermocompression bonding sheet, 160°C to 180°C when a polypropylene sheet is selected, 220°C to 240°C when a polystyrene sheet is selected, 250°C to 270°C when a polyethylene terephthalate sheet is selected, and preferably 160°C to 180°C when a polyethylene naphthalate is selected.

Advantages of the Invention

[0010] According to the present invention, even if the wafer is cut into individual device chips by performing cutting processing, the problem of cutting chips adhering to the surface of the device chips is solved, and the problem that a part of the adhesive layer adheres to and remains on the surface of the wafer and the quality of the device chips deteriorates, which occurred in the conventional technology, is solved. In addition, when the thermocompression bonding sheet and the wafer are cut simultaneously, the cutting blade cuts the wafer while winding in the viscous thermocompression bonding sheet, resulting in problems such as chipping or chipping occurring on the outer periphery of the device chip. On the other hand, by performing the cutting process in two steps: a thermocompression bonding sheet removal step and a dicing step, the above problems are avoided, and the problems of chipping or chipping occurring on the outer periphery of the device chip are solved.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of a wafer processing method configured based on the present invention will be described in detail with reference to the accompanying drawings.

[0013] When implementing the wafer processing method of this embodiment, first, as shown in FIG. 1, a wafer 10 to be processed is prepared. The wafer 10 is, for example, a wafer in which a plurality of devices 12 including lenses are partitioned by a division planned line 14 on the surface 10a of a semiconductor substrate of gallium arsenide (GaAs). Note that the division planned line 14 of this embodiment is formed with a width of about 50 μm. After preparing the wafer 10, it is transported to a thermocompression bonding apparatus 20 (only a part is shown in the figure) shown in FIG. 1 and placed on the chuck table 23 of the thermocompression bonding apparatus 20 with the back surface 10b side facing downward. The chuck table 23 includes, as shown in the figure, a suction chuck 21 and a frame body 22 surrounding the suction chuck 21. The suction chuck 21 is made of a breathable member, is connected to a suction source (not shown), and a suction negative pressure is generated on the surface of the suction chuck 21. After placing the wafer 10, the thermocompression bonding sheet T1 is placed on the surface 10a side of the wafer 10 from above. Thus, the thermocompression bonding sheet disposition process is completed.

[0014] The thermocompression bonding sheet T1 is a sheet that exhibits adhesive force when heated, and is selected from, for example, a polyolefin-based sheet or a polyester-based sheet. When the thermocompression bonding sheet T1 is selected from polyolefin-based sheets, it is preferably any one of a polyethylene sheet, a polypropylene sheet, and a polystyrene sheet. When selected from the polyester-based sheets, it is preferably any one of a polyethylene terephthalate sheet and a polyethylene naphthalate sheet. In the present embodiment, as the thermocompression bonding sheet T1, a polyethylene sheet is selected and will be described below.

[0015] As shown below FIG. 1, the thermocompression bonding sheet T1 covers the entire wafer 10 and is formed in a circular shape with a dimension larger than that of the suction chuck 21 constituting the chuck table 23. When the above-described thermocompression bonding sheet disposition step is performed and the wafer 10 and the thermocompression bonding sheet T1 are placed on the chuck table 23 of the thermocompression bonding apparatus 20, an aspiration source (not shown) is operated to aspirate the lower surface side of the thermocompression bonding sheet T1 together with the wafer 10 with a negative pressure V to make the inside in a vacuum state, remove the air between the thermocompression bonding sheet T1 and the suction chuck 21, and bring the thermocompression bonding sheet into close contact with the surface 10a side of the wafer 10.

[0016] Next, a thermocompression bonding step of heating the thermocompression bonding sheet T1 and thermocompression bonding it to the surface 10a of the wafer 10 is performed. The thermocompression bonding step will be described more specifically with reference to FIG. 2. FIG. 2(a) shows a first form of the thermocompression bonding step. In this first form, a thermocompression bonding roller 24 is disposed with respect to the thermocompression bonding apparatus 20 as shown in the figure. The surface 24a of the thermocompression bonding roller 24 is coated with a fluororesin and is provided with heating means (not shown) inside, and the surface 24a can be heated to a desired temperature. This thermocompression bonding roller 24 is positioned above the wafer 10 and the thermocompression bonding sheet T1 held by suction on the chuck table 23.

[0017] If the thermocompression roller 24 is positioned above the wafer 10, activate the heating means of the thermocompression roller 24 and press it against the wafer 10 from above the thermocompression sheet T1. Further, activate the rotational drive means (not shown) to rotate the thermocompression roller 24 in the direction indicated by the arrow R1 and move it to the end of the wafer 10 in the direction indicated by the arrow R2. The heating temperature during heating by the heating means is set to the melting temperature of polyethylene (120°C to 140°C) at which the thermocompression sheet T1 made of polyethylene exhibits adhesive force. Due to this heating during thermocompression, the thermocompression sheet T1 exhibits adhesive force and is thermocompression bonded to the entire surface 10a of the wafer 10.

[0018] Figure 2(b) shows a second form of the thermocompression process. In this second form, instead of the above-described thermocompression roller 24, a hot air heater 25 is disposed. Also in the second form, similar to the above-described first form, the wafer 10 and the thermocompression sheet T1 are placed on the chuck table 23 of the thermocompression device 20, and an aspiration source (not shown) is activated to aspirate the lower surface side of the thermocompression sheet T1 together with the wafer 10 with a negative pressure V to make the inside in a vacuum state, and remove the air between the thermocompression sheet T1 and the suction chuck 21 to bring the thermocompression sheet into close contact with the surface 10a side of the wafer 10.

[0019] Next, position the hot air heater 25 above the wafer 10, activate the hot air heater 25, and blow hot air onto the thermocompression sheet T1 covering the wafer 10. The hot air is also set to heat the thermocompression sheet T1 to 120°C to 140°C. Due to this hot air heating, the thermocompression sheet T1 exhibits adhesive force and the thermocompression sheet T1 is thermocompression bonded to the entire surface 10a of the wafer 10.

[0020] Furthermore, FIG. 2(c) shows a third form of the thermocompression bonding process. In this third form, instead of the above-described thermocompression bonding roller 24 and hot air heater 25, a heating heater 26 is disposed. Also in this third form, similar to the above-described first and second forms, the wafer 10 and the thermocompression bonding sheet T1 are placed on the chuck table 23 of the thermocompression bonding apparatus 20, and a suction source (not shown) is operated to suck the lower surface side of the thermocompression bonding sheet T1 together with the wafer 10 with a negative pressure V to make the inside a vacuum state, and the air between the thermocompression bonding sheet T1 and the suction chuck 21 is removed to bring the thermocompression bonding sheet into close contact with the surface 10a side of the wafer 10.

[0021] Next, the heating heater 26 is positioned above the wafer 10 and operated to heat the thermocompression bonding sheet T1 covering the wafer 10. The heating heater 26 is also set to heat the thermocompression bonding sheet T1 to 120° C. to 140° C., and due to the action of this heating heater 26, the thermocompression bonding sheet T1 exhibits an adhesive force and is thermocompression bonded to the entire surface 10a of the wafer 10.

[0022] As described above, if the thermocompression bonding process is carried out, the cutter 30 shown in FIG. 3 is positioned on the chuck table 23. The cutter 30 has a blade 34 disposed at the tip of a rotary shaft 33 rotatably supported by a casing 32, and the blade 34 can be rotated in the direction indicated by arrow R3 by a drive motor (not shown). While rotating the blade 34 in the direction indicated by arrow R3, a cut is made from above the thermocompression bonding sheet T1 to the outer peripheral edge of the wafer 10, and the chuck table 23 is rotated in the direction indicated by arrow R4. As a result, as shown in the lower part of FIG. 3, the thermocompression bonding sheet T1 is cut into a circular shape along the outer peripheral edge of the wafer 10 while being thermocompression bonded to the surface 10a of the wafer 10.

[0023] Next, a dicing tape support process of supporting the back surface 10b of the wafer 10 with a dicing tape T2 is carried out. With reference to FIG. 4, the dicing tape support process will be described more specifically.

[0024] When performing the dicing tape support process, as shown in FIG. 4, an annular frame F having an opening Fa capable of accommodating the wafer 10 and a dicing tape T2 having an adhesive layer on a surface larger than the opening Fa and smaller than the outer shape of the frame F are prepared. The back surface 10b of the wafer 10 is positioned downward at the center of the opening Fa of the frame F, and the back surface 10b of the wafer 10 is positioned at the center of the dicing tape T2. The outer peripheral edge of the dicing tape T2 is adhered to the lower surface side of the frame F to be integrated, and the back surface 10b of the wafer 10 is supported by the dicing tape T2 (see the lower part of FIG. 4).

[0025] Next, the wafer 10 supported by the dicing tape T2 in the dicing tape support process is transported to a cutting device 40 shown in FIG. 5(a). The cutting device 40 includes a cutting means 42. The cutting means 42 includes a spindle housing 43, a rotating shaft 44 rotatably supported by the spindle housing 43, a first cutting blade 45 fixed to the tip of the rotating shaft 44, a blade cover 46 disposed at the tip of the spindle housing 43 to cover the first cutting blade 45, and a cutting water supply nozzle 47 for injecting cutting water to the cutting position by the first cutting blade 45. An electric motor (not shown) is disposed behind the spindle housing 43, and the cutting blade 45 is rotated in the direction indicated by arrow R5 by the rotating shaft 44 driven by the electric motor. The above-described first cutting blade 45 has, for example, a diameter of 50 mm and a thickness of about 35 μm, and is formed by fixing abrasive grains made of diamond or the like with a bonding material such as metal or resin. The abrasive grains are composed of a relatively large particle size of 4 to 6 μm.

[0026] Once the wafer 10 is transported to the above-described cutting device 40, the surface 10a of the wafer 10 is held upward and the dicing tape T2 is held downward by a holding means (not shown), aligning a predetermined dividing line 14 of the wafer 10 in the X direction and performing alignment with the first cutting blade 45. Next, the first cutting blade 45 is rotated in the direction indicated by the arrow R5 at a speed of, for example, 30,000 rpm, and cutting water is supplied from the cutting water supply nozzle 47 at a rate of, for example, 2 L / min to cut the first cutting blade 45 into the surface 10a side. At this time, the amount of cutting from the surface 10a side is set to an amount that removes the thermocompression bonding sheet T1 disposed on the surface 10a of the wafer 10 and reaches a position where the wafer 10 is not cut, as shown in FIG. 5(b). In the illustrated embodiment, a slight remainder 110 of the thermocompression bonding sheet T1 remains between the tip of the first cutting blade 45 and the surface 10a of the wafer 10.

[0027] As described above, if the first cutting blade 45 is cut from the surface 10a side, the wafer 10 is processed and fed in the X direction at a speed of, for example, 3 mm / sec, and the thermocompression bonding sheet T1 is cut and removed in a so-called down-cut state to form a thermocompression bonding sheet removal groove 100 along the planned division line 14. Further, the first cutting blade 45 is indexed and fed onto the planned division line 14 that is adjacent to the planned division line 14 where the thermocompression bonding sheet removal groove 100 is formed in the Y direction and where the thermocompression bonding sheet removal groove 100 is not formed, and the thermocompression bonding sheet removal groove 100 is formed in the same manner as above. By repeating these operations, the above-mentioned thermocompression bonding sheet removal grooves 100 are formed along all the planned division lines 14 along the X direction. Next, the holding means is rotated by 90 degrees to align the direction orthogonal to the direction in which the thermocompression bonding sheet removal groove 100 was formed first with the X direction, and the above-described cutting process is performed on all the planned division lines 14 newly aligned in the X direction to form thermocompression bonding sheet removal grooves 100 along all the planned division lines 14 formed on the surface 10a of the wafer 10. In this way, thermocompression bonding sheet removal grooves 100 from which the thermocompression bonding sheet T1 has been removed are formed along all the planned division lines 14 formed on the surface 10a of the wafer 10. As described above, the thermocompression bonding sheet removal process for cutting and removing the thermocompression bonding sheet T1 along the planned division line 14 of the wafer 10 by the first cutting blade 45 is completed.

[0028] As described above, if the thermocompression bonding sheet removal process is performed, a dividing process for dividing the wafer into individual device chips along the planned division line is performed. This dividing process will be described in more detail with reference to FIG. 6.

[0029] As shown in Fig. 6(a), the cutting process uses the above-described cutting device 40. However, when performing the cutting process of this embodiment, instead of the first cutting blade 45 attached to the cutting device 40 when performing the thermocompression bonding sheet removal process, a second cutting blade 48 is attached. For the second cutting blade 48, for example, it is preferable to use a blade with a thickness thinner than the thickness D1 of the first cutting blade 45, or to use a blade obtained by bonding fine abrasive grains (e.g., with a particle size of 1 to 2 μm) to the first cutting blade 45 using a bonding material. Note that the second cutting blade 48 of this embodiment will be described as adopting a blade with a thickness D2 (about 15 μm) thinner than the thickness D1 (about 35 μm) of the first cutting blade 45, as shown in Fig. 6(b).

[0030] When performing this cutting process, the wafer 10 that has undergone the thermocompression bonding sheet removal process is held as it is by the cutting device 40 and positioned directly below the cutting means 42 equipped with the second cutting blade 48, as shown in Fig. 6(a). Next, on the surface 10a of the wafer 10, the predetermined division planned line 14 where the above-described thermocompression bonding sheet removal groove 100 is formed is aligned in the X direction, and alignment with the second cutting blade 48 is performed. Then, the second cutting blade 48 rotated and driven in the direction indicated by the arrow R6 at a speed of, for example, 30000 rpm is positioned at the center of the thermocompression bonding sheet removal groove 100 of the division planned line 14 aligned in the X direction, and cutting water is supplied from the cutting water supply nozzle 47 at an amount of, for example, 2 L / min while cutting in from the surface 10a side. At this time, the amount of cutting in from the surface 10a side is set to the amount for completely dividing the wafer 10 along the division planned line 14, as shown in Fig. 6(b).

[0031] As described above, if the second cutting blade 48 is cut from the surface 10a side, the wafer 10 is processed and fed in the X direction at a speed of, for example, 3 mm / second, and cutting is performed in a state of so-called down-cut to form a dividing groove 102 corresponding to the thickness D2 of the second cutting blade 48. Further, the second cutting blade 48 is indexed and fed onto a division planned line 14 that is adjacent in the Y direction to the thermocompression bonding sheet removal groove 100 and the division planned line 14 where the division groove 102 is formed and where the division groove 102 is not formed, and a division groove 102 is formed at the center of the thermocompression bonding sheet removal groove 100 in the same manner as above. By repeating these operations, the thermocompression bonding sheet removal groove 100 and the division groove 102 are formed along all the division planned lines 14 along the X direction. Next, the holding means is rotated by 90 degrees, the direction orthogonal to the direction in which the division groove 102 was previously formed is aligned with the X direction, and the above-described cutting process is performed on all the division planned lines 14 newly aligned in the X direction, and the thermocompression bonding sheet removal groove 100 and the division groove 102 are formed along all the division planned lines 14 formed on the surface 10a of the wafer 10, and the wafer 10 is divided along the division planned lines 14 to form individual device chips 12'. As described above, the division process of dividing the wafer 10 into individual device chips 12' along the division planned line 14 by the cutting means 42 including the second cutting blade 48 is completed.

[0032] Note that, if necessary, after the above-described division process is completed, the thermocompression bonding sheet T1 adhered to the surface 10a side of the wafer 10 divided into individual device chips 12' may be removed. When removing the thermocompression bonding sheet T1, the surface 10a side of the wafer 10 is heated or cooled to reduce the adhesive force of the thermocompression bonding sheet T1, and a peeling tape (not shown) is attached to the thermocompression bonding sheet T1 side, etc., to remove the thermocompression bonding sheet T1 from the surface 10a of the wafer 10 divided into individual device chips 12'.

[0033] According to the above-described embodiment, even if the wafer 10 is divided into individual device chips 12' by performing the dividing step, the problem of cutting chips adhering to the surface of the device chip 12' is solved, and the problem that occurs in the conventional technology, that is, a part of the adhesive layer adheres to and remains on the surface 10a of the wafer 10, resulting in a decrease in the quality of the device chip 12', is solved. Further, when the thermocompression bonding sheet T1 and the wafer 10 are cut together, the cutting blade cuts the wafer 10 while winding the viscous thermocompression bonding sheet T1, resulting in problems such as chipping occurring on the outer periphery of the device chip 12' or chipping occurring. In contrast, by performing the cutting process separately into a thermocompression bonding sheet removing step and a dividing step, the above-described problems are avoided, and problems such as chipping occurring on the outer periphery of the device chip 12' or chipping occurring are solved.

[0034] Further, in the above-described embodiment, since the thickness D1 of the first cutting blade 45 used in the thermocompression bonding sheet removing step is set to be thicker than the thickness D2 of the second cutting blade 48 used in the dividing step, when using the second cutting blade 48 to cut into the thermocompression bonding sheet removing groove 100 formed previously, cutting can be performed along the dividing line 14 of the wafer 10 without winding the thermocompression bonding sheet T1, and problems such as chipping occurring on the outer periphery of the device chip 12' or chipping occurring are solved more effectively. Further, in the above-described embodiment, since the particle size of the abrasive grains of the first cutting blade 45 used in the thermocompression bonding sheet removing step is set to be a large particle size and the particle size of the abrasive grains of the second cutting blade 48 used in the dividing step is set to be a small particle size, the thermocompression bonding sheet removing step and the dividing step can be appropriately performed.

[0035] In the above-described embodiment, the heat-sealing sheet T1 was described as a polyethylene sheet. However, the present invention is not limited thereto, and it can be selected from either a polyolefin-based sheet or a polyester-based sheet. When heating the heat-sealing sheet T1 to bond it to the surface 10a of the wafer 10, the heating temperature is set to 160°C to 180°C when a polypropylene sheet is selected as the heat-sealing sheet T1, 220°C to 240°C when a polystyrene sheet is selected, 250°C to 270°C when a polyethylene terephthalate sheet is selected, and preferably 160°C to 180°C when a polyethylene naphthalate is selected.

[0036] The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the thickness D1 of the first cutting blade 45 is made thicker than the thickness D2 of the second cutting blade 48. However, the first cutting blade 45 and the second cutting blade 48 may be the same cutting blade, that is, the same cutting blade may be used in both the heat-sealing sheet removing step and the dividing step.

[0037] Also, in the above-described embodiment, it was described that the cutting blade attached to the cutting means 42 of the cutting device 40 is exchanged and the heat-sealing sheet removing step and the dividing step are sequentially performed. However, the present invention is not limited thereto. For example, a cutting device provided with two cutting means may be prepared, the first cutting blade 45 may be attached to one cutting means, the second cutting blade 48 may be attached to the other cutting means, the heat-sealing sheet removing step may be performed, and then the dividing step may be performed.

Explanation of Reference Numerals

[0038] 10: Wafer 10a: Surface 10b: Back surface 12: Device 14: Scribing line 20: Heat-sealing device 21: Suction chuck 22: Frame 23: Chuck table 24: Thermal pressure bonding roller 25: Warm air heater 26: Heating heater 30: Cutter 32: Casing 33: Rotating shaft 34: Blade 40: Cutting device 42: Cutting means 43: Spindle housing 44: Rotating shaft 45: First cutting blade 46: Blade cover 47: Cutting water supply nozzle 48: Second cutting blade 100: Thermal pressure bonding sheet removal groove 102: Division groove 110: Remaining part F: Frame Fa: Opening T1: Thermal pressure bonding sheet T2: Dicing tape

Claims

1. A method for processing a wafer that divides a wafer formed on a surface partitioned by a division planned line into individual device chips by a plurality of devices, comprising: A thermocompression bonding sheet disposing step of disposing a thermocompression bonding sheet on the surface of the wafer; A thermocompression bonding step of heating the thermocompression bonding sheet and pressing it onto the surface of the wafer; A dicing tape supporting step of supporting the back surface of the wafer with a dicing tape; A thermocompression bonding sheet removing step of cutting and removing the thermocompression bonding sheet along the division planned line by cutting means having a rotatable cutting blade; A dividing step of dividing the wafer into individual device chips along the division planned line by cutting means having a rotatable cutting blade; Comprising and configured, In the thermocompression bonding sheet removing step, when cutting and removing the thermocompression bonding sheet along the division planned line, a method for processing a wafer that cuts and removes the thermocompression bonding sheet within a range where the cutting blade does not reach the wafer.

2. The method for processing a wafer according to claim 1, wherein the thickness of the cutting blade used in the thermocompression bonding sheet removing step is thicker than the thickness of the cutting blade used in the dividing step.

3. The method for processing a wafer according to claim 1 or 2, wherein the abrasive grains constituting the cutting blade used in the thermocompression bonding sheet removing step are coarser than the abrasive grains constituting the cutting blade used in the dividing step.

4. The method for processing a wafer according to any one of claims 1 to 3, wherein the thermocompression bonding sheet is a polyolefin-based sheet or a polyester-based sheet.

5. The method for processing a wafer according to claim 4, wherein the polyolefin-based sheet is any one of a polyethylene sheet, a polypropylene sheet, and a polystyrene sheet, and the polyester-based sheet is any one of a polyethylene terephthalate sheet and a polyethylene naphthalate sheet.

6. The heating temperature when heating the thermocompression bonding sheet and pressing it onto the surface of the wafer is 120°C to 140°C when a polyethylene sheet is selected as the thermocompression bonding sheet, 160°C to 180°C when a polypropylene sheet is selected, 220°C to 240°C when a polystyrene sheet is selected, 250°C to 270°C when a polyethylene terephthalate sheet is selected, and 160°C to 180°C when a polyethylene naphthalate is selected. The method for processing a wafer according to claim 5.

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