Wafer manufacturing method

Abstract

To suppress occurrence of a resin residue on one surface of a slice wafer when a protective member is peeled.SOLUTION: There is provided a manufacturing method for manufacturing a wafer by grinding both surfaces of a slice wafer (W) which is sliced from an ingot and has waviness and warpage. The manufacturing method includes coating the whole surface of a lower surface (W2) of the slice wafer with a coating agent (R), then supplying a liquid resin (M) to a sheet (S) protruding to the outside of the slice wafer, curing the sheet while pressing and spreading it by the lower surface of the slice wafer, and thereby forming a protective member (H). Then, the method includes holding the slice wafer on a chuck table (32) through the protective member, grinding an upper surface (W1) of the slice wafer by a grinding stone (35), then peeling the protective member from the lower surface of the slice wafer while gripping the outer peripheral edge of the sheet, holding the upper surface of the slice wafer on the chuck table, and grinding the upper surface of the slice wafer by the grinding stone.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a wafer.

Background Art

[0002] Patent Document 1 discloses a protective member forming device that spreads a liquid resin on one surface of a sliced wafer obtained by slicing an ingot and cures it to form a protective member composed of the resin and a sheet. In forming such a protective member, the liquid resin is spread over the entire one surface of the sliced wafer, and the resin is spread so as to cover the outer peripheral edge of the sliced wafer and then cured. Such a liquid resin increases the adhesive force so as not to peel off from one surface during grinding of the other surface of the sliced wafer after curing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the adhesive force of the liquid resin is increased as described above, when the protective member is peeled off from the sliced wafer, resin may remain on one surface of the sliced wafer. Therefore, when grinding one surface of the next sliced wafer, the grinding wheel may be clogged by the remaining resin. Thus, there is a problem that operations and adjustments such as dressing the lower surface of the grinding wheel are required, and the grinding time becomes long.

[0005] In view of this point, the present invention is made, and one of the objects is to provide a method for manufacturing a wafer that can suppress the occurrence of resin residue on one surface of the sliced wafer when the protective member is peeled off.

Means for Solving the Problems

[0006] A method for manufacturing a wafer according to an aspect of the present invention is a method for manufacturing a wafer by grinding both surfaces of a sliced wafer having undulations and warpage sliced from an ingot, the method comprising: a coating agent applying step of applying a coating agent to the entire surface of one surface of the sliced wafer; a protective member forming step of supplying a liquid resin to a sheet protruding outside the sliced wafer and spreading and curing it on one surface of the sliced wafer to form a protective member; a first grinding step of holding the sliced wafer via the protective member on a chuck table of a grinding device and grinding the other surface of the sliced wafer with a grinding wheel; a peeling step of gripping the outer peripheral edge of the sheet and peeling the protective member from one surface of the sliced wafer; and a second grinding step of holding the other surface of the sliced wafer on the chuck table and grinding one surface of the sliced wafer with the grinding wheel.

Advantages of the Invention

[0007] According to the present invention, by performing the above-described coating agent applying step, a layer of the coating agent can be formed on the entire surface of one surface of the sliced wafer before forming the protective member obtained by curing the liquid resin. Thereby, it is possible to suppress the occurrence of resin residue on one surface of the sliced wafer when the protective member is peeled off from the sliced wafer.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, with reference to the accompanying drawings, a method for manufacturing a wafer according to this embodiment will be described. FIG. 1A shows an explanatory diagram of a wafer holding step, and FIG. 1B shows an explanatory diagram of a coating agent application step. Note that the steps shown in each figure in this embodiment are merely examples and are not limited to this configuration.

[0010] As shown in FIG. 1, first, a wafer holding step of holding a sliced wafer W on a holding table 10 of a protection member forming apparatus (not shown) is performed. The holding table 10 has a lower surface formed as a holding surface 11, and the holding surface 11 is connected to a predetermined suction source (not shown). The holding table 10 is provided so as to be movable in the vertical direction via a lifting mechanism 12.

[0011] A glass table 16 is provided below the holding table 10. The glass table 16 is made of a light-transmitting material such as quartz glass and is formed in a disc shape. The upper surface of the glass table 16 is a flat sheet holding surface 17 for placing and holding the sheet S.

[0012] A curing mechanism 18 for applying an external stimulus to the liquid resin M (see FIG. 2B) dropped on the sheet S on the sheet holding surface 17 and curing it is provided below the glass table 16. The curing mechanism 18 includes a plurality of ultraviolet irradiation units 19 capable of emitting ultraviolet rays UV (see FIG. 2D), and irradiates the liquid resin M with ultraviolet rays UV through the light-transmitting glass table 16 and sheet S to cure it. The ultraviolet irradiation unit 19 may use an LED.

[0013] The slice wafer W is, for example, a circular az slice wafer formed by thinly cutting (slicing) a cylindrical ingot with a wire saw or the like. Although not shown in the drawings, it has undulations (wave shapes following the upper and lower surfaces) and warpage (curved shapes). Further, fine irregularities are formed on its upper and lower surfaces. The slice wafer W has a lower surface W2 whose surface facing downward in FIG. 1A is one surface, and an upper surface W1 whose surface facing upward is the other surface. A chamfered portion W3 presenting an arc surface extending from the upper surface W1 to the lower surface W2 is formed on the outer peripheral edge (outer peripheral side surface) of the slice wafer W.

[0014] In the wafer holding step, the slice wafer W is conveyed to the holding table 10 by a conveyance mechanism (not shown). At the holding table 10, a suction source is communicated with the holding surface 11 to apply a suction force, and the upper surface W1 of the slice wafer W is sucked and held on the holding surface 11. The lower surface W2 of the slice wafer W held by the holding table 10 is exposed.

[0015] After the wafer holding step is completed, as shown in FIG. 1B, a coating agent application step is performed. In the coating agent application step, the coating agent R is made to adhere to the surface of the coating roller 21. Then, the coating roller 21 with the coating agent R adhering to its surface is rolled in the radial direction of the slice wafer W with respect to the exposed lower surface W2 of the slice wafer W held by the holding table 10. Thereby, the coating agent R is applied to the entire lower surface W2 of the slice wafer W, and a layer of the coating agent R is formed on the entire lower surface W2 of the slice wafer W.

[0016] As the coating agent R, for example, a fluororesin (not shown) such as polytetrafluoroethylene (PTFE) is used.

[0017] After the coating agent application process is completed, as shown in FIG. 2, a protective member forming process is carried out. In the protective member forming process, the following sheet supply process, liquid resin supply process, expansion process, and curing process are carried out in sequence. FIG. 2 shows each process of the protective member forming process, FIG. 2A shows the sheet supply process, FIG. 2B shows the liquid resin supply process, FIG. 2C shows the expansion process, and FIG. 2D shows the explanatory diagrams of the curing process, respectively.

[0018] In the sheet supply process shown in FIG. 2A, the sheet S is pulled out from a sheet supply unit (not shown) in which the sheet S is wound in a roll shape through a clamp unit 23, and the sheet S is cut to a predetermined length and sucked and held on the sheet holding surface 17. Note that the area of the sheet S on the sheet holding surface 17 at this stage is larger than the area of the lower surface W2 of the slice wafer W, and the sheet S is provided in a shape that protrudes outside the slice wafer W.

[0019] After the sheet supply process is completed, as shown in FIG. 2B, a liquid resin supply process is carried out. In the liquid resin supply process, after positioning the resin supply nozzle 25 above the sheet S placed on the sheet holding surface 17, the liquid resin M is supplied (dropped) from the resin supply nozzle 25 toward the sheet S on the upper surface side of the glass table 16. The liquid resin M supplied from the resin supply nozzle 25 accumulates near the center of the upper surface of the sheet S in a range narrower than the area of the slice wafer W.

[0020] The liquid resin M has a property of curing by external stimuli. In the present embodiment, an ultraviolet curable liquid resin M that cures by ultraviolet irradiation is used. The liquid resin M may be a heat curable type.

[0021] After the liquid resin supply process is completed, as shown in FIG. 2C, an expansion process is performed. In the expansion process, the sliced wafer W held on the holding table 10 is disposed to face upward of the liquid resin M on the sheet S, and the holding table 10 is lowered at a predetermined feed rate by driving the elevating mechanism 12. By this lowering, the lower surface W2 of the sliced wafer W approaches the glass table 16, and the liquid resin M is spread (expanded) in the radial direction of the sliced wafer W by the lower surface W2 of the sliced wafer W.

[0022] Here, in the expansion process of the present embodiment, the outer peripheral edge of the liquid resin M to be expanded is adjusted so as not to protrude from the lower surface W2 of the sliced wafer W and not to reach the chamfered portion W3. In other words, in the expansion process, the liquid resin M is spread on the lower surface W2 inside the chamfered portion W3 of the sliced wafer W. Such adjustment can be exemplified by providing a load detection unit (not shown) on the holding table 10 and controlling the lowering amount of the holding table 10 by the elevating mechanism 12 based on the pressing force applied to the liquid resin M detected by such load detection unit.

[0023] After the expansion process is completed, as shown in FIG. 2D, a curing process is performed. In the curing process, ultraviolet rays UV having an intensity (wavelength) for curing the liquid resin M are irradiated from the ultraviolet irradiation unit 19 toward the sheet holding surface 17 for a predetermined time. The ultraviolet rays UV emitted from the ultraviolet irradiation unit 19 pass through the glass table 16 and the sheet S and reach the liquid resin M, and the liquid resin M, which is an ultraviolet curable resin, is cured. By curing the liquid resin M, a protective member H that covers the lower surface W2 of the sliced wafer W is formed, and the lower surface W2 of the sliced wafer W is protected by the protective member H. By forming the protective member H, the protective member forming process including the curing process is completed. In this specification, the liquid resin M after curing is referred to as "resin" and is given a common reference numeral "M".

[0024] After the protective member forming process is completed, as shown in FIG. 3, a first grinding process, a peeling process, and a second grinding process are performed in order. FIG. 3A shows an explanatory diagram of the first grinding process, FIG. 3B shows the peeling process, and FIG. 3C shows an explanatory diagram of the second grinding process.

[0025] In the first grinding process shown in FIG. 3A, a grinding mechanism 31 and a chuck table 32 of a grinding apparatus (not shown) are used. The grinding mechanism 31 includes a spindle 33 having an axial center in the vertical direction, a grinding wheel 34 attached to the lower end of the spindle 33, and a grinding stone 35 annularly fixed to the lower part of the grinding wheel 34. The grinding mechanism 31 can rotate the grinding wheel 34 at a predetermined rotational speed by rotating the spindle 33 by a motor (not shown). The grinding mechanism 31 is provided so as to be movable in the vertical direction via a lifting mechanism 36. The chuck table 32 sucks and holds the slice wafer W with its upper surface as a holding surface, and is rotatable around the axis of the rotating shaft 37.

[0026] In the first grinding process, the H-side of the protection member is placed on the chuck table 32 to expose the upper surface W1 of the slice wafer W, and the slice wafer W is sucked and held by the holding surface of the chuck table 32 via the protection member H. Subsequently, while rotating the chuck table 32 around the axis of the rotating shaft 37, the grinding wheel 34 of the grinding mechanism 31 is rotated and the grinding mechanism 31 is lowered by driving the lifting mechanism 36, and the rotating grinding stone 35 is brought into contact with the upper surface W1 of the slice wafer W. Thereby, the upper surface W1 of the slice wafer W is ground by the grinding stone 35, and the undulations and warpage on the upper surface W1 of the slice wafer W are removed.

[0027] After the first grinding process is completed, as shown in FIG. 3B, a peeling process is performed. In the peeling process, a holding table 40 of a grinding apparatus (not shown) and a gripping portion 41 of a peeling unit (not shown) are used. The holding table 40 is provided so as to be able to suck and hold the slice wafer W with its lower surface as a holding surface. The gripping portion 41 is capable of gripping an end portion of the sheet S and is provided so as to be relatively movable with respect to the holding table 40 by a moving mechanism (not shown).

[0028] In the peeling step, with the upper surface W1 of the sliced wafer W being adsorbed and held by the holding surface of the holding table 40, the outer peripheral edge of the sheet S is gripped by the gripping portion 41. Subsequently, after the protective member H is inverted so as to be folded back by the movement of the gripping portion 41, the gripping portion 41 is moved in a horizontal direction or in an inclined direction gradually away from the holding table 40 with respect to the horizontal direction. As a result, depending on the movement distance of the gripping portion 41, the peeling of the protective member H proceeds from right to left in FIG. 3B, and the resin M of the protective member H is peeled off from the lower surface W2 of the sliced wafer W coated with the coating agent R. When the entire protective member H is peeled off from the lower surface W2 of the sliced wafer W, the peeling step is completed.

[0029] After the peeling step is completed, as shown in FIG. 3C, the second grinding step is performed. Although not particularly limited, in the second grinding step of the present embodiment, the same grinding mechanism 31 and chuck table 32 as those in the first grinding step are used.

[0030] In the second grinding step, after inverting the vertical orientation of the sliced wafer W from the peeling step, the sliced wafer W is conveyed onto the chuck table 32 and sucked and held. Thus, the upper surface W1 of the sliced wafer W ground in the first grinding step is directed downward and placed and sucked and held on the chuck table 32, and the lower surface W2 of the sliced wafer W from which the protective member H has been peeled off in the peeling step is directed upward and exposed. Subsequently, while rotating the chuck table 32 around the axis of the rotating shaft 37 and rotating the grinding wheel 34, the grinding mechanism 31 is lowered, and the rotating grinding stone 35 is brought into contact with the lower surface W2 of the sliced wafer W. As a result, the lower surface W2 of the sliced wafer W is ground by the grinding stone 35, and while the undulations and warpage on the lower surface W2 of the sliced wafer W are removed, the sliced wafer W is thinned to a predetermined thickness. When the second grinding step is completed, a wafer having both surfaces of the sliced wafer W ground is formed (manufactured).

[0031] According to the above embodiment, since the coating agent application step is carried out, a layer of the coating agent R can be formed on the entire lower surface W2 of the slice wafer W before forming the protective member H obtained by curing the liquid resin M. By forming such a layer of the coating agent R, when peeling the protective member H in the peeling step, it is possible to suppress the resin M from remaining on the lower surface W2 of the slice wafer W.

[0032] Thereby, even when the adhesive force of the liquid resin M itself is high, it is possible to prevent the resin M from remaining on the lower surface W2 of the slice wafer W and clogging the grinding wheel 35 in the second grinding step. As a result, operations and adjustments such as dressing of the grinding wheel 35 can be eliminated, and it is possible to avoid an increase in the grinding time.

[0033] Also, in the expansion step, since the outer peripheral edge of the liquid resin M is expanded so as not to fit within the lower surface W2 of the slice wafer W and reach the chamfered portion W3, it is possible to suppress the resin M from remaining on the outer peripheral edge of the slice wafer W.

[0034] Note that the present invention is not limited to the above embodiment, and various modifications can be made and implemented. In each of the above embodiments, the size, shape, etc. illustrated in the attached drawings are not limited thereto, and can be appropriately changed within the range in which the effects of the present invention are exhibited. In addition, various modifications can be made and implemented as long as the scope of the object of the present invention is not deviated from.

[0035] In the above embodiment, in the coating agent application step, the coating roller 21 is rotated to apply the coating agent R. However, as long as the coating agent R can be applied in the same manner, for example, spin coating, spraying which is a two-fluid of air and the coating agent R, application of the coating agent R in a spray form by an ultrasonic vibration plate, spraying, or application using a brush may be changed. For example, the protective member forming apparatus may include a cleaning unit that rotates a table holding the sliced wafer W by injecting a two-fluid of water and air to clean the sliced wafer W. In the coating agent application step, the coating agent R may be dropped onto the center of the sliced wafer W cleaned by this cleaning unit, and the table may be rotated at high speed to perform spin coating.

[0036] Also, the sheet supply step and the liquid resin supply step in the protective member forming step may be performed during or before the coating agent application step. For example, when supplying the sheet, the coating agent R may be applied in parallel.

[0037] Also, when a thermosetting resin is used for the liquid resin M, in the curing mechanism 18, a heat generating part such as a heater is provided instead of the ultraviolet irradiation part 19.

[0038] Also, the grinding mechanisms 31 and the chuck table 32 used in the first grinding step and the second grinding step may be common or different as long as they can perform grinding as described above.

[0039] Also, the surface on which the protective member H is formed on the sliced wafer W may be either of the two surfaces in the thickness direction. The surface on which the protective member H is formed and ground in the second grinding step is one surface, and the surface ground in the first grinding step on the opposite side is the other surface.

[0040] Also, in the expansion step, even if the outer peripheral edge of the liquid resin M expands until it reaches the chamfered portion W3 of the sliced wafer W, it is possible to suppress the resin M from remaining on the lower surface W2 due to the layer of the coating agent R formed on the entire lower surface W2. Note that since the coating agent R is removed from the entire lower surface W2 by performing the second grinding step, there is no need to newly add a removal step for removing the coating agent R.

Industrial Applicability

[0041] As described above, the present invention has an effect of preventing the resin from remaining when the protective member is peeled off from one surface of the slice wafer.

Explanation of Reference Numerals

[0042] 32: Chuck table 35: Grinding wheel H: Protective member M: Liquid resin R: Coating agent S: Sheet W: Slice wafer W1: Upper surface (the other surface) W2: Lower surface (one surface) W3: Chamfered portion

Claims

【Claim 1】 A method for manufacturing a wafer by grinding both sides of a sliced wafer having undulations and warpage sliced from an ingot, comprising: a coating agent application step of applying a coating agent to the entire surface of one side of the sliced wafer; a protective member forming step of forming a protective member by supplying a liquid resin to a sheet protruding outside the sliced wafer and spreading and curing it on one side of the sliced wafer; a first grinding step of holding the sliced wafer via the protective member on a chuck table of a grinding device and grinding the other side of the sliced wafer with a grinding wheel; a peeling step of gripping the outer peripheral edge of the sheet and peeling the protective member from one side of the sliced wafer; a second grinding step of holding the other side of the sliced wafer on the chuck table and grinding one side of the sliced wafer with the grinding wheel; The method for manufacturing a wafer comprising the above steps.

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