Wafer manufacturing method and stacked device chip manufacturing method

Abstract

To provide a method for manufacturing wafers that can suppress a decrease in yield of laminated device chips.SOLUTION: A wafer manufacturing method includes a wafer preparing step of preparing a wafer including a semiconductor device formed in each of multiple regions demarcated by multiple streets intersecting each other, a removing step of separating, from the wafer, a defective device region including a semiconductor device determined to be a defective product among the multiple semiconductor devices formed in the wafer, and a fitting step of fitting, into a through hole formed by separating the defective device region from the wafer, a device chip including a semiconductor device as a non-defective product having the same functions as those of the semiconductor device determined to be a defective product and having a size capable of being fitted into the through hole.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a wafer having a plurality of semiconductor devices, and a method for manufacturing a stacked device chip having a plurality of stacked semiconductor devices. [Background technology]

[0002] The device chip manufacturing process uses a wafer in which semiconductor devices are formed in multiple regions defined by multiple streets (planned dividing lines) arranged in a grid pattern. By dividing this wafer along the streets, multiple device chips, each equipped with a semiconductor device, are obtained. The device chips are incorporated into various electronic devices, such as mobile phones and personal computers.

[0003] In recent years, technology for manufacturing device chips (stacked device chips) that include multiple stacked semiconductor devices has been put to practical use. For example, stacked device chips can be obtained by stacking multiple device chips and connecting the semiconductor devices with through-silicon vias (TSVs) that penetrate the device chips from top to bottom. The use of through-silicon vias allows for shorter wiring that connects the semiconductor devices compared to wire bonding, etc., which allows for the miniaturization of stacked device chips and the improvement of their processing speed.

[0004] A method called WoW (Wafer on Wafer) has been proposed as a method for manufacturing stacked device chips. In this method, a stacked wafer is formed by stacking multiple wafers and connecting the semiconductor devices on each wafer with electrodes formed to penetrate the stacked wafers. The stacked wafer is then divided along the streets to manufacture stacked device chips.

[0005] However, wafers used in manufacturing stacked device chips may contain defective semiconductor devices (defective devices). When a stacked wafer formed by stacking wafers containing defective devices is divided, stacked device chips containing defective devices are manufactured. If some of the semiconductor devices contained in a stacked device chip are defective, the stacked device chip as a whole will be determined to be defective (defective chip) even if the other semiconductor devices are non-defective. Therefore, in manufacturing stacked device chips, defective devices have a significant impact on yield reduction.

[0006] Therefore, before stacking multiple wafers, an inspection is performed to determine whether the semiconductor devices contained in each wafer are pass or fail. Then, for example, based on the number, arrangement, etc. of defective devices contained in the wafer, an optimal combination of wafers to be used in manufacturing the stacked device chip is determined (see Patent Document 1). This minimizes the number of stacked device chips containing defective devices, and suppresses a decrease in yield. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-134334 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, even if a wafer contains defective devices, the number of stacked device chips (defective chips) containing the defective devices can be minimized by determining the wafer combination based on the semiconductor device inspection results. However, since a wafer contains defective devices, when stacked device chips are manufactured using this wafer, at least a certain number of defective chips will be manufactured. Therefore, there is a limit to how much the number of defective chips can be reduced.

[0009] The present invention has been made in view of the above problems, and aims to provide a method for manufacturing a wafer that can suppress a decrease in the yield of stacked device chips, and a method for manufacturing stacked device chips using the wafer. [Means for solving the problem]

[0010] According to one aspect of the present invention, a method for manufacturing a wafer includes a wafer preparation step of preparing a wafer having semiconductor devices formed in a plurality of regions partitioned by a plurality of intersecting streets, a removal step of separating from the wafer defective device regions including semiconductor devices determined to be defective among the plurality of semiconductor devices formed on the wafer, and an insertion step of inserting device chips into through holes formed by separating the defective device regions from the wafer, the device chips including non-defective semiconductor devices having the same functions as the semiconductor devices determined to be defective, and having a size that can be inserted into the through holes. In the removal step, a laser beam is irradiated along the streets surrounding the semiconductor devices determined to be defective. In the removing step, a second surface of the wafer opposite to the first surface on which the semiconductor device is formed is ground to expose a processed area processed by irradiation with the laser beam or a crack propagating from the processed area on the second surface of the wafer. A method for manufacturing a wafer is provided.

[0011] Preferably, in the removal step, a modified layer that functions as a starting point for separating the defective device region is formed along the street by irradiating the laser beam along the street with the focal point of the laser beam having a wavelength that is transparent to the wafer positioned inside the wafer. Also preferably, in the removal step, a region of the wafer along the street is removed by irradiating the laser beam along the street with the focal point of the laser beam having a wavelength that is absorbent for the wafer positioned inside the street. Also preferably, in the removal step, a region of the wafer along the street is removed by irradiating the laser beam along the street through the liquid column with the focal point of the laser beam having a wavelength that is absorbent for the wafer positioned inside a liquid column formed by spraying a liquid toward the wafer.

[0012] Preferably, the method for manufacturing the wafer further includes a grinding step, before carrying out the removing step, of attaching a protective member to a first surface side of the wafer on which the semiconductor device is formed, and grinding a second surface side of the wafer opposite to the first surface to thin the wafer to a predetermined thickness.

[0014] Preferably, in the removing step, an etching solution is supplied to the processed region processed by the irradiation of the laser beam or a crack propagating from the processed region. Also, preferably, in the removing step, a plasmatized gas is supplied to the processed region processed by the irradiation of the laser beam or a crack propagating from the processed region.

[0015] Preferably, the method for manufacturing the wafer further includes a resin filling step of filling the gap between the device chip and the wafer with resin after the embedding step is performed, and a resin grinding step of grinding the resin formed outside the gap after the resin filling step is performed.

[0016] According to another aspect of the present invention, a method for manufacturing a semiconductor wafer includes a wafer preparation step of preparing a first wafer and a second wafer, each having semiconductor devices formed in a plurality of regions defined by a plurality of intersecting streets; a removal step of separating from the first wafer defective device regions including semiconductor devices determined to be defective among the plurality of semiconductor devices formed on the first wafer; an embedding step of embedding device chips, which include non-defective semiconductor devices having the same functions as the semiconductor devices determined to be defective, into through holes formed by separating the defective device regions from the first wafer; a wafer stacking step of stacking the second wafer on the first wafer to form a laminated wafer; and a dividing step of dividing the laminated wafer along the streets to form laminated device chips including the plurality of stacked semiconductor devices, wherein in the removal step, a laser beam is irradiated along the streets surrounding the semiconductor devices determined to be defective. In the removing step, a second surface of the first wafer opposite to the first surface on which the semiconductor device is formed is ground to expose a processed region processed by irradiation with the laser beam or a crack propagating from the processed region on the second surface of the first wafer. A method for manufacturing stacked device chips is provided. [Effects of the Invention]

[0017] In a wafer manufacturing method according to one aspect of the present invention, defective device regions containing semiconductor devices determined to be defective are removed from a wafer, and device chips containing non-defective semiconductor devices are fitted into gaps formed by the removal of the defective device regions. This allows for the manufacture of wafers that do not contain defective devices. Furthermore, by stacking wafers that do not contain defective devices to form a stacked wafer, and then dividing this stacked wafer, stacked device chips that do not contain defective devices can be manufactured. As a result, a decrease in the yield of stacked device chips is suppressed. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1(A) is a perspective view showing a wafer, FIG. 1(B) is a cross-sectional view showing the wafer, and FIG. 1(C) is a perspective view showing a semiconductor device. [Figure 2] FIG. [Figure 3] FIG. 3(A) is a cross-sectional view showing the wafer in the removing step, and FIG. 3(B) is a perspective view showing the wafer in which through-holes have been formed. [Figure 4] Figure 4(A) is a cross-sectional view showing a wafer irradiated with a laser beam, Figure 4(B) is a cross-sectional view showing a wafer on which a modified layer has been formed, and Figure 4(C) is a cross-sectional view showing a modified layer including multiple modified regions. [Figure 5] FIG. 5(A) is a plan view showing a rectangular route with rounded corners, FIG. 5(B) is a plan view showing a rectangular route, and FIG. 5(C) is a plan view showing a plurality of linear routes. [Figure 6] FIG. 2 is a cross-sectional view showing the wafer after grinding. [Figure 7] FIG. 7(A) is a cross-sectional view showing a wafer to be subjected to plasma etching, and FIG. 7(B) is a cross-sectional view showing the wafer after plasma etching. [Figure 8] FIG. 8A is a cross-sectional view of the wafer when the adhesive layer is pre-treated, and FIG. 8B is a cross-sectional view of the wafer when the defective device regions are separated. [Figure 9] FIG. 2 is a cross-sectional view showing an ultrasonic irradiation unit. [Figure 10] FIG. 10(A) is a cross-sectional view showing a wafer to be irradiated with a laser beam, and FIG. 10(B) is a cross-sectional view showing a wafer in which a groove is formed. [Figure 11] FIG. 11(A) is a cross-sectional view showing a wafer fixed to a support substrate, and FIG. 11(B) is a cross-sectional view showing the wafer after grinding. [Figure 12] FIG. 12(A) is a cross-sectional view showing a wafer irradiated with a laser beam, and FIG. 12(B) is a cross-sectional view showing a wafer fixed to a support substrate. [Figure 13] FIG. 13(A) is a cross-sectional view showing a wafer irradiated with a laser beam via a liquid column, and FIG. 13(B) is a cross-sectional view showing a wafer fixed to a support substrate. [Figure 14] Figure 14(A) is a cross-sectional view showing a wafer on which a mask layer is formed, Figure 14(B) is a cross-sectional view showing a wafer to be subjected to plasma etching, and Figure 14(C) is a cross-sectional view showing the wafer after plasma etching. [Figure 15] FIG. 15(A) is a perspective view showing a wafer for preparing device chips, and FIG. 15(B) is a perspective view showing the wafer divided into a plurality of device chips. [Figure 16] FIG. 10 is a perspective view showing the wafer in the embedding step. [Figure 17] FIG. 17(A) is a cross-sectional view showing a wafer in which a device chip is embedded, and FIG. 17(B) is a plan view showing a through-hole. [Figure 18] Figure 18(A) is a cross-sectional view of a wafer when plasma etching is performed on the adhesive layer, Figure 18(B) is a cross-sectional view of a wafer with part of the adhesive layer removed, and Figure 18(C) is a cross-sectional view of a wafer with a device chip with an adhesive layer attached embedded therein. [Figure 19] FIG. 19(A) is a cross-sectional view showing the wafer in the resin filling step, and FIG. 19(B) is a cross-sectional view showing the wafer in the resin grinding step. [Figure 20] FIG. 2 is a cross-sectional view showing a laminated wafer. [Figure 21] FIG. 21(A) is a cross-sectional view showing the laminated wafer in the dividing step, and FIG. 21(B) is a cross-sectional view showing the laminated wafer divided into a plurality of laminated device chips. [Figure 22] Figure 22(A) is a cross-sectional view showing a wafer in which grooves are formed by sandblasting, Figure 22(B) is a cross-sectional view showing a wafer in which grooves are formed by water jet processing, and Figure 22(C) is a cross-sectional view showing a wafer in which grooves are formed by drilling. [Figure 23] FIG. 23(A) is a cross-sectional view showing a wafer fixed to a support substrate, and FIG. 23(B) is a cross-sectional view showing the wafer after grinding. [Figure 24]Figure 24(A) is a cross-sectional view showing a wafer in which through-holes are formed by sandblasting, Figure 24(B) is a cross-sectional view showing a wafer in which through-holes are formed by water jet processing, and Figure 24(C) is a cross-sectional view showing a wafer in which through-holes are formed by drilling. [Figure 25] FIG. 2 is a cross-sectional view showing a wafer fixed to a support substrate. [Figure 26] FIG. 2 is a cross-sectional view showing a wafer undergoing plasma etching. [Figure 27] FIG. 27(A) is a plan view showing an area to be processed by sandblasting or water jet processing, and FIG. 27(B) is a plan view showing an area to be processed by drilling. [Figure 28] FIG. 28(A) is a cross-sectional view showing a wafer irradiated with a laser beam, and FIG. 28(B) is a cross-sectional view showing a wafer in which a groove has been formed. [Figure 29] FIG. 2 is a plan view showing a path along which a laser beam is scanned. [Figure 30] FIG. 30(A) is a cross-sectional view showing a wafer fixed to a support substrate, and FIG. 30(B) is a cross-sectional view showing the wafer after grinding. [Figure 31] FIG. 31(A) is a cross-sectional view showing a wafer irradiated with a laser beam, and FIG. 31(B) is a cross-sectional view showing a wafer fixed to a support substrate. [Figure 32] FIG. 2 is a cross-sectional view showing a wafer held by a holding table. [Figure 33] Figure 33(A) is a cross-sectional view showing a wafer from which a defective device area has been removed by sandblasting, Figure 33(B) is a cross-sectional view showing a wafer from which a defective device area has been removed by water jet processing, and Figure 33(C) is a cross-sectional view showing a wafer from which a defective device area has been removed by drilling. [Figure 34] FIG. 34(A) is a cross-sectional view showing a wafer fixed to a support substrate, and FIG. 34(B) is a cross-sectional view showing the wafer after grinding. [Figure 35]Figure 35(A) is a cross-sectional view showing a wafer in which a through-hole is formed by sandblasting, Figure 35(B) is a cross-sectional view showing a wafer in which a through-hole is formed by water jet processing, and Figure 35(C) is a cross-sectional view showing a wafer in which a through-hole is formed by drilling. [Figure 36] FIG. 2 is a cross-sectional view showing a wafer fixed to a support substrate. [Figure 37] FIG. 37(A) is a plan view showing an area to be processed by sandblasting or water jet processing, and FIG. 37(B) is a plan view showing an area to be processed by drilling. DETAILED DESCRIPTION OF THE INVENTION

[0019] (Embodiment 1) Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, an example of the structure of a wafer that can be used in this embodiment will be described. Fig. 1(A) is a perspective view showing a wafer 11, and Fig. 1(B) is a cross-sectional view showing the wafer 11.

[0020] For example, the wafer 11 is a silicon wafer formed in a disk shape and has a front surface (first surface) 11a and a back surface (second surface) 11b opposite to the front surface 11a. The front surface 11a and the back surface 11b are formed to be approximately parallel to each other.

[0021] The wafer 11 is divided into a plurality of rectangular regions by a plurality of streets (planned dividing lines) 13 arranged in a grid pattern so as to intersect with one another. Semiconductor devices 15, such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems), are formed in each of the regions divided by the streets 13 on the front surface 11a of the wafer 11.

[0022] There are no limitations on the material, shape, structure, size, etc. of the wafer 11. For example, the wafer 11 may be a wafer made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, etc. There are also no limitations on the type, number, shape, structure, size, arrangement, etc. of the semiconductor devices 15.

[0023] 1(C) is a perspective view showing a semiconductor device 15. For example, the semiconductor device 15 has a plurality of electrodes 17 that are exposed on the surface of the semiconductor device 15 and are connected to other wiring, electrodes, semiconductor devices, etc. Note that connection electrodes such as bumps may be formed on the surfaces of the electrodes 17.

[0024] Furthermore, a plurality of electrodes (via electrodes, through electrodes) 19 are embedded inside each of a plurality of regions defined by the streets 13 of the wafer 11. The electrodes 19 are formed in a columnar shape along the thickness direction of the wafer 11 and are connected to the electrodes 17 of the semiconductor device 15. There are no limitations on the material of the electrodes 19, and metals such as copper, tungsten, and aluminum can be used, for example.

[0025] The electrodes 19 are each formed from the semiconductor device 15 toward the back surface 11b of the wafer 11, and the length (height) of the electrodes 19 is less than the thickness of the wafer 11. Therefore, the electrodes 19 are not exposed on the back surface 11b of the wafer 11, but are buried inside the wafer 11. In addition, an insulating layer (not shown) is provided between the wafer 11 and the electrodes 19 to insulate the wafer 11 from the electrodes 19.

[0026] When the back surface 11b of the wafer 11 is thinned by grinding, etching, or the like, the electrodes 19 become exposed on the back surface 11b of the wafer 11. When a plurality of wafers 11 with the electrodes 19 exposed on the back surface 11b are stacked, a stacked wafer is obtained that includes a plurality of semiconductor devices 15 stacked on top of each other. The stacked semiconductor devices 15 are connected to each other via the electrodes 19.

[0027] The stacked wafer is divided along the streets 13 by cutting, laser processing, or the like. As a result, a device chip (stacked device chip) having a plurality of stacked semiconductor devices 15 is manufactured.

[0028] The wafer 11 may contain defective semiconductor devices 15. Figures 1A and 1B show an example in which the wafer 11 contains a defective device 15a. For example, the defective device 15a corresponds to a semiconductor device 15 that does not meet a predetermined standard for electrical characteristics.

[0029] Wafers 11 each including a defective device 15a are stacked to form a stacked wafer, and when this stacked wafer is divided, stacked device chips each including a defective device 15a are manufactured. If some of the semiconductor devices 15 included in the stacked device chip are defective devices 15a, the stacked device chip as a whole will be determined to be defective (a defective chip) even if the other semiconductor devices 15 are non-defective.

[0030] Therefore, in the wafer manufacturing method according to this embodiment, the defective devices 15a are removed from the wafer 11. Then, good semiconductor devices 15 are fitted into the removed areas (gaps) formed in the wafer 11 by removing the defective devices 15a. In this way, a wafer 11 that does not include any defective devices 15a is manufactured. A specific example of the wafer manufacturing method according to this embodiment will be described below.

[0031] First, a wafer 11 (see FIGS. 1(A) and 1(B)) is prepared (wafer preparation step), in which semiconductor devices 15 are formed in each of a plurality of regions defined by a plurality of intersecting streets 13. Note that, since a stacked wafer will be formed by stacking a plurality of wafers in a later process, it is preferable to prepare at least two wafers in the wafer preparation step.

[0032] Next, the wafer 11 is ground to thin it (grinding step). For example, a grinding device is used to grind the wafer 11. FIG. 2 is a front view showing the grinding device 2. The grinding device 2 includes a chuck table 4 that holds the wafer 11 and a grinding unit 6 that grinds the wafer 11.

[0033] The upper surface of the chuck table 4 forms a flat holding surface 4a that holds the wafer 11. The holding surface 4a is connected to a suction source (not shown) such as an ejector via a flow path (not shown) formed inside the chuck table 4. A moving mechanism (not shown) that moves the chuck table 4 in the horizontal direction is connected to the chuck table 4. The moving mechanism may be a ball screw type moving mechanism or a turntable that supports and rotates the chuck table 4. A rotation drive source (not shown) such as a motor that rotates the chuck table 4 around a rotation axis that is approximately parallel to the vertical direction (up and down direction) is connected to the chuck table 4.

[0034] A grinding unit 6 is disposed above the chuck table 4. The grinding unit 6 includes a cylindrical spindle 8 disposed along the vertical direction. A disk-shaped mount 10 made of metal or the like is fixed to the tip end (lower end) of the spindle 8. A rotation drive source (not shown), such as a motor, that rotates the spindle 8 is connected to the base end (upper end) of the spindle 8.

[0035] A grinding wheel 12 for grinding the wafer 11 is attached to the underside of the mount 10. The grinding wheel 12 is provided with an annular base 14 made of a metal such as stainless steel or aluminum and formed to have approximately the same diameter as the mount 10. A plurality of grinding stones 16 are fixed to the underside of the base 14. For example, the plurality of grinding stones 16 are formed in a rectangular parallelepiped shape and are arranged at approximately equal intervals along the outer periphery of the base 14.

[0036] The grinding wheel 12 rotates around a rotation axis that is roughly parallel to the vertical direction by power transmitted from a rotation drive source via the spindle 8 and the mount 10. A ball screw type moving mechanism (not shown) that raises and lowers the grinding unit 6 in the vertical direction is connected to the grinding unit 6. Furthermore, a nozzle 18 is provided near the grinding unit 6 to supply a grinding fluid 20 such as pure water to the wafer 11 held by the chuck table 4 and the plurality of grinding wheels 16.

[0037] For example, the back surface 11b side of the wafer 11 is ground by the grinding device 2. In this case, first, a protective member 21 is attached to the front surface 11a side of the wafer 11 on which the semiconductor devices 15 are formed. As a result, the semiconductor devices 15 are covered and protected by the protective member 21.

[0038] The protective member 21 may be a circular tape (protective tape) including a film-like substrate and an adhesive layer (glue layer) on the substrate. For example, the substrate may be made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer may be made of an epoxy-, acrylic-, or rubber-based adhesive. Alternatively, the adhesive layer may be made of an ultraviolet-curable resin that hardens when exposed to ultraviolet light.

[0039] The wafer 11 is then held by the chuck table 4. Specifically, the wafer 11 is placed on the chuck table 4 so that the front surface 11a (protective member 21 side) faces the holding surface 4a and the back surface 11b side is exposed upward. In this state, when negative pressure from a suction source is applied to the holding surface 4a, the front surface 11a side of the wafer 11 is suction-held by the chuck table 4 via the protective member 21.

[0040] Next, the chuck table 4 is moved below the grinding unit 6. Then, while the chuck table 4 and the grinding wheel 12 are rotated in a predetermined direction at a predetermined rotation speed, the grinding wheel 12 is lowered toward the chuck table 4. The speed at which the grinding wheel 12 is lowered at this time is adjusted so that the grinding stone 16 is pressed against the wafer 11 with an appropriate force.

[0041] When the grinding wheel 16 comes into contact with the back surface 11b of the wafer 11, the back surface 11b of the wafer 11 is ground away. This causes the back surface 11b of the wafer 11 to be ground, thinning the wafer 11. Then, when the wafer 11 is thinned to a predetermined thickness, the grinding is stopped. Thereafter, the protective member 21 is peeled off and removed from the wafer 11.

[0042] Before or after the grinding step, each of the semiconductor devices 15 included in the wafer 11 is inspected to determine whether the semiconductor device 15 is a pass or a fail product. In the inspection of the semiconductor device 15, for example, a metal probe is applied to the electrodes 17 exposed on the surface of the semiconductor device 15 to measure the electrical characteristics of the semiconductor device 15 (probing). Then, based on whether the measured electrical characteristics satisfy a predetermined standard, the semiconductor device 15 is determined to be a pass or a fail product.

[0043] If the wafer 11 contains a defective semiconductor device 15 (defective device 15a), the semiconductor device 15 is determined to be defective by inspection, and the position of the semiconductor device 15 determined to be defective is recorded.

[0044] Next, a defective device region including semiconductor devices 15 (defective devices 15a) determined to be defective among the plurality of semiconductor devices 15 formed on the wafer 11 is removed from the wafer 11 (removal step). Fig. 3(A) is a cross-sectional view showing the wafer 11 in the removal step.

[0045] For example, in the removal step, the wafer 11 is removed along the four streets 13 surrounding the defective device 15a. As a result, a rectangular parallelepiped defective device region 11c including the defective device 15a is cut out and separated from the wafer 11. Then, a rectangular parallelepiped through-hole (removed region) 11d extending from the front surface 11a to the back surface 11b of the wafer 11 is formed in the location where the defective device region 11c of the wafer 11 was located.

[0046] 3(B) is a perspective view showing the wafer 11 in which the through-holes 11d are formed. By removing the defective device regions 11c, a wafer 11 that does not include defective devices 15a is obtained. Note that if the grinding step (see FIG. 2) described above is performed before the removal step, the wafer 11 is thinned, making it easier to remove the defective device regions 11c from the wafer 11. However, if there is no problem in removing the defective device regions 11c, the grinding step may be omitted.

[0047] Various methods can be used to remove the defective device region 11c. For example, a laser beam is irradiated along the street 13 surrounding the defective device 15a to separate the defective device region 11c from the wafer 11. An example of laser processing of the wafer 11 in the removal step will be described below.

[0048] 4(A) is a cross-sectional view showing the wafer 11 irradiated with the laser beam 32A. In the removal step, first, the front surface 11a of the wafer 11 is fixed to a support substrate 23 that supports the wafer 11. For example, the support substrate 23 is a plate-shaped member made of silicon, glass, ceramics, or the like, and the front surface 11a of the wafer 11 is fixed to the support substrate 23 via an adhesive layer 25. As a result, the wafer 11 is supported by the support substrate 23 with the back surface 11b side exposed.

[0049] There are no restrictions on the material of the adhesive layer 25, and it can be appropriately selected depending on the materials of the wafer 11 and the support substrate 23. For example, the adhesive layer 25 can be made of an adhesive made of a thermosetting resin that hardens when heated, an adhesive made of a thermoplastic resin that softens when heated, or an adhesive made of an ultraviolet-curing resin that hardens when irradiated with ultraviolet light.

[0050] The adhesive layer 25 may also be a sheet (thermocompression sheet) that can be fixed to the wafer 11 and the support substrate 23 by applying heat and pressure. For example, the adhesive layer 25 is a flexible sheet made of a thermoplastic resin having a melting point lower than that of the wafer 11 and the support substrate 23, and does not include an adhesive (glue layer). When the wafer 11 is pressed against the support substrate 23 via the thermocompression sheet while heating the thermocompression sheet, the thermocompression sheet comes into close contact with the wafer 11 and the support substrate 23. This fixes the wafer 11 to the support substrate 23. Specific examples of the sheet include a polyolefin (PO)-based sheet and a polyester (PE)-based sheet.

[0051] A polyolefin sheet is a sheet made of a polymer synthesized using an alkene as a monomer. Examples of polyolefin sheets include polyethylene sheets, polypropylene sheets, and polystyrene sheets. Sheets made of a copolymer of propylene and ethylene and sheets made of an olefin elastomer can also be used.

[0052] A polyester sheet is a sheet made of a polymer synthesized using dicarboxylic acid (a compound having two carboxyl groups) and diol (a compound having two hydroxyl groups) as monomers. Examples of polyester sheets include polyethylene terephthalate sheets and polyethylene naphthalate sheets. Polytrimethylene terephthalate sheets, polybutylene terephthalate sheets, and polybutylene naphthalate sheets can also be used.

[0053] When fixing the wafer 11 to the support substrate 23 via the adhesive layer 25, it is preferable that the adhesive layer 25 is not firmly bonded to the wafer 11 and the support substrate 23, but that the wafer 11 is temporarily fixed to the support substrate 23. This makes it easier for the defective device region 11c to peel off from the adhesive layer 25 when separating the defective device region 11c from the wafer 11 in a later step (see FIG. 8(B)).

[0054] For example, if the adhesive layer 25 is an adhesive made of a thermosetting resin, the wafer 11 is fixed to the support substrate 23 by performing a heat treatment at a lower temperature or for a shorter time than in the case of completely bonding the thermosetting resin to the wafer 11 and the support substrate 23. Also, if the adhesive layer 25 is an adhesive made of a thermoplastic resin, the thermoplastic resin is heated to a predetermined temperature to soften it, and then the wafer 11 is fixed to the support substrate 23.

[0055] When the adhesive layer 25 is an adhesive made of an ultraviolet curable resin, the wafer 11 is fixed to the support substrate 23 without performing a heat treatment on the ultraviolet curable resin. When the adhesive layer 25 is a thermocompression sheet, the wafer 11 is fixed to the support substrate 23 by performing a heat treatment at a lower temperature or for a shorter time than when the thermocompression sheet is completely fixed to the wafer 11 and support substrate 23.

[0056] Also, instead of the support substrate 23, a tape made of resin or the like may be attached to the front surface 11a side of the wafer 11. Examples of the structure and material of the tape are the same as those of the protective member 21 (see FIG. 2).

[0057] Next, laser processing is performed on the wafer 11. A laser processing device is used for laser processing the wafer 11. The laser processing device includes a chuck table (not shown) that holds the wafer 11, and a laser irradiation unit 30A that irradiates the wafer 11 with a laser beam 32A. The laser irradiation unit 30A includes a laser oscillator that oscillates a laser with a predetermined wavelength, and a condenser (condensing lens) that condenses the laser beam emitted from the laser oscillator.

[0058] The irradiation conditions of the laser beam 32A are set so that the region of the wafer 11 irradiated with the laser beam 32A is modified (altered) by multiphoton absorption. Specifically, the wavelength of the laser beam 32A is set so that at least a portion of the laser beam 32A is transmitted through the wafer 11. That is, the laser irradiation unit 30A irradiates the wafer 11 with the laser beam 32A having a wavelength that is transparent to the wafer 11. In addition, other irradiation conditions of the laser beam 32A (output, pulse width, spot diameter, repetition frequency, etc.) are also set so that the wafer 11 is appropriately modified.

[0059] Then, with the focal point of the laser beam 32A positioned inside the wafer 11, the laser beam 32A is irradiated along the four streets 13 surrounding the defective device 15a. Note that it is sufficient that the laser beam 32A is irradiated so as to surround the defective device 15a, and the specific scanning path of the laser beam 32A is set appropriately.

[0060] 5(A) to 5(C) show examples of scanning paths of laser beam 32A. Fig. 5(A) is a plan view showing a path 34A having a rounded rectangular shape, Fig. 5(B) is a plan view showing a rectangular path 34B, and Fig. 5(C) is a plan view showing multiple straight paths 34C. Path 34A, path 34B, and multiple paths 34C are each set to overlap with street 13.

[0061] For example, laser beam 32A is scanned along a substantially rectangular path 34A having four arc-shaped corners so as to surround defective device 15a. Laser beam 32A may also be scanned along a rectangular path 34B that surrounds defective device 15a. When laser beam 32A is scanned along path 34A or path 34B, laser beam 32A is continuously irradiated onto wafer 11 so as to surround defective device 15a (in one stroke).

[0062] Alternatively, the laser beam 32A may be scanned along four linear paths 34C that are aligned with the four streets 13 surrounding the defective device 15a. Note that the paths 34C are not connected to each other, and the laser beam 32A is intermittently irradiated so as to surround the defective device 15a.

[0063] 4(B) is a cross-sectional view showing the wafer 11 on which a modified layer (degraded layer) 27 has been formed. When a laser beam 32A is irradiated along the street 13 surrounding the defective device 15a, the wafer 11 is modified by multiphoton absorption, and the modified layer 27 is formed inside the wafer 11 along the street 13. The region where the modified layer 27 has been formed becomes more fragile than other regions of the wafer 11. Therefore, for example, when an external force is applied to the wafer 11, the wafer 11 breaks along the modified layer 27. In other words, the modified layer 27 functions as a starting point (trigger) for separation of the defective device region 11c.

[0064] In particular, it has been confirmed that irradiating the laser beam 32A along the path 34A shown in Fig. 5(A) or the path 34C shown in Fig. 5(C) effectively suppresses the occurrence of unintended irregular cracks at the four corners of the paths 34A and 34C. In this case, the modified layers 27 formed at the four corners of the paths 34A and 34C function correctly as starting points for division, making it easier to accurately separate the defective device region 11c.

[0065] The modified layer 27 may be formed by irradiating the laser beam 32A along each street 13 multiple times while changing the height position of the focal point of the laser beam 32A. In this case, the modified layer 27 is composed of modified regions formed in multiple stages along the thickness direction of the wafer 11.

[0066] 4(C) is a cross-sectional view showing a modified layer 27 including multiple modified regions (degraded regions) 27a. For example, inside the wafer 11, multiple stages of modified regions 27a are formed along each street 13 at different depth positions in the thickness direction of the wafer 11.

[0067] The modified regions 27a may be formed so as not to overlap each other in a plan view. Specifically, as shown in FIG. 4(C), the modified regions 27a formed on the back surface 11b of the wafer 11 are formed at positions farther from the defective device 15a in the horizontal direction (direction perpendicular to the thickness direction of the wafer 11). In this case, a modified layer 27 is formed that is inclined with respect to the thickness direction of the wafer 11 (see FIG. 4(B)), which makes it easier to separate the defective device region 11c from the wafer 11 in a later process (see FIG. 8(B)). However, there are no limitations on the shape of the modified layer 27, and the modified layer 27 may be formed parallel to the thickness direction of the wafer 11.

[0068] Next, the back surface 11b of the wafer 11 is ground to expose the processed region (modified layer 27) processed by the irradiation of the laser beam 32A or cracks propagating from the processed region (modified layer 27) on the back surface 11b of the wafer 11. For example, a grinding apparatus 2 shown in FIG. 2 is used to grind the wafer 11.

[0069] The back surface 11b of the wafer 11 is ground by bringing the grinding wheel 16 into contact with the back surface 11b of the wafer 11 held by the chuck table 4. Then, for example, the wafer 11 is ground and thinned until the modified layer 27 is exposed on the back surface 11b of the wafer 11.

[0070] 6 is a cross-sectional view showing the wafer 11 after grinding. When the grinding wheel 16 (see FIG. 2) is pressed against the wafer 11 to grind the wafer 11, an external force (pressure) is applied to the wafer 11, causing the wafer 11 to fracture along the modified layer 27. Furthermore, a crack 29 generated in the modified layer 27 propagates and reaches the surface 11a of the wafer 11. As a result, a defective device region 11c is separated from the wafer 11.

[0071] The cracks 29 that propagate from the modified layer 27 to the surface 11a of the wafer 11 may also occur when the modified layer 27 is formed by irradiation with the laser beam 32A (see FIGS. 4(A) and 4(B)). Specifically, by appropriately setting the irradiation conditions of the laser beam 32A and the position where the modified layer 27 is formed, the cracks 29 that occur simultaneously with the formation of the modified layer 27 can be made to reach the surface 11a of the wafer 11.

[0072] After grinding the wafer 11, it is preferable to perform an etching process on the wafer 11. For example, plasma etching is performed on the wafer 11. A plasma processing apparatus is used for the plasma etching. The plasma processing apparatus includes a chuck table having a holding surface for holding the wafer 11, and a chamber (processing chamber) that houses the chuck table.

[0073] 7A is a cross-sectional view showing a wafer 11 to be plasma etched. When performing plasma etching, a chamber is sealed with the wafer 11 held by a chuck table, and an etching gas 36 is supplied into the chamber. The plasma processing apparatus then converts the gas 36 in the chamber into a plasma state containing ions and radicals using a high-frequency voltage. This allows the plasma-converted gas 36 to be supplied to the wafer 11.

[0074] For example, if the wafer 11 is a silicon wafer, a fluorine-based gas such as CF4 or SF6 is used as the gas 36. However, the components of the gas 36 are appropriately selected depending on the material of the wafer 11. Then, the gas 36 in a plasma state acts on the wafer 11, and the wafer 11 is subjected to plasma etching.

[0075] 7(B) is a cross-sectional view showing the wafer 11 after plasma etching. When the plasma gas 36 is supplied to the back surface 11b side of the wafer 11, the gas 36 penetrates into the modified layer 27 and the cracks 29, and etches the inside of the modified layer 27 and the cracks 29. As a result, the gap between the wafer 11 and the defective device region 11c is widened, and the defective device region 11c is reliably separated from the wafer 11.

[0076] However, the gas 36 may be converted into plasma outside the chamber and then supplied into the chamber through a metal supply pipe. In this case, as the plasma-converted gas 36 passes through the supply pipe, ions contained in the gas are adsorbed to the inner wall of the supply pipe, making it difficult for the gas 36 to reach the chamber. As a result, gas 36 with a high radical ratio is introduced into the chamber and supplied to the wafer 11. Gas 36 with a high radical ratio easily penetrates narrow regions within the wafer 11, making it easier for the gas 36 to etch the modified layer 27 and the interior of the cracks 29.

[0077] Furthermore, the type of etching process is not limited to plasma etching. For example, wet etching may be performed on the wafer 11 by supplying an etching solution to the back surface 11b of the wafer 11. Specifically, if the wafer 11 is a silicon wafer, an etching solution containing potassium hydroxide (KOH), tetramethylammonium hydroxide (TMAH), or the like is supplied to the wafer 11. The etching solution then penetrates into the modified layer 27 and the cracks 29, etching the interiors of the modified layer 27 and the cracks 29, and the modified layer 27 and the cracks 29 are thereby enlarged.

[0078] If the modified layer 27 (see FIG. 4(B)) formed by irradiation with the laser beam 32A is present on the back surface 11b side of the wafer 11 relative to the electrode 19, it is preferable to grind and thin the wafer 11 until the modified layer 27 is completely removed. In this case, a wafer 11 is obtained that does not include the modified layer 27 and in which only cracks 29 propagating from the modified layer 27 remain. Removing the modified layer 27 from the wafer 11 in this manner prevents a decrease in the flexural strength (bending strength) of the device chips that are ultimately obtained by dividing the wafer 11.

[0079] When the modified layer 27 is removed from the wafer 11 as described above, the grinding exposes the crack 29 on the back surface 11b side of the wafer 11, and the defective device region 11c is separated from the wafer 11. Then, plasma gas 36 or an etching solution is supplied into the crack 29, and the crack 29 is enlarged.

[0080] Furthermore, when the modified layer 27 is formed by irradiation with the laser beam 32A (see FIGS. 4(A) and 4(B)), or when the back surface 11b of the wafer 11 is ground (see FIG. 6), a crack may occur that propagates from the modified layer 27 toward the back surface 11b of the wafer 11. In this case, when the crack is exposed on the back surface 11b of the wafer 11 by grinding the wafer 11, the defective device region 11c is separated from the wafer 11.

[0081] Next, the defective device region 11c is removed from the wafer 11. Specifically, the defective device region 11c is separated from the wafer 11 by peeling the defective device region 11c from the adhesive layer 25 and picking it up.

[0082] When separating the defective device region 11c from the wafer 11, it is preferable to first perform a treatment (pre-treatment) to partially reduce the adhesive strength of the adhesive layer 25. For example, by supplying a chemical solution to the adhesive layer 25 through the modified layer 27 and the cracks 29, the adhesive strength of the adhesive layer 25 is partially reduced or the adhesive layer 25 is partially removed.

[0083] Furthermore, if the adhesive layer 25 is made of a material whose adhesive strength decreases when a predetermined amount of energy is applied (heating, irradiation with electromagnetic waves, etc.), the adhesive strength of the adhesive layer 25 may be decreased by applying energy to the adhesive layer 25. For example, if the adhesive layer 25 is an adhesive made of a thermoplastic resin, the adhesive strength of the adhesive layer 25 can be decreased by heating the adhesive layer 25. Furthermore, if the adhesive layer 25 is an adhesive made of an ultraviolet-curable resin, the adhesive strength of the adhesive layer 25 can be decreased by irradiating the adhesive layer 25 with ultraviolet light.

[0084] Alternatively, a tape including a film-like substrate, a thermally foamable layer provided on one side of the substrate, and an adhesive layer provided on the other side of the substrate can be used as adhesive layer 25. The thermally foamable layer of this tape is formed by adding an expanding material that expands when heated to an adhesive.

[0085] The adhesive for the thermally foamed layer may be an acrylic adhesive, a rubber adhesive, a vinyl alkyl ether adhesive, a silicone adhesive, a polyester adhesive, a polyamide adhesive, a urethane adhesive, etc. The expansion material for the thermally foamed layer may be microspheres that expand when heated (thermally expandable microspheres), a foaming material that foams when heated, etc.

[0086] Heat-expandable microspheres are formed by encapsulating a substance that expands upon heating in elastic microcapsules. Examples of substances that expand upon heating include propane, propylene, and butene. An example of a commercially available tape containing heat-expandable microspheres is Rivalpha (registered trademark) manufactured by Nitto Denko Corporation. Examples of foaming agents that expand upon heating include inorganic foaming agents such as ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium boron hydroxide, and azides, as well as various organic foaming agents.

[0087] The above-mentioned tape is attached to the wafer 11 and the support substrate 23 so that the thermally foamed layer side contacts the wafer 11 and the adhesive layer side contacts the support substrate 23. When the tape is heated, the expansion material contained in the thermally foamed layer expands in the heated area of ​​the tape, forming irregularities, and the adhesive strength of the tape to the wafer 11 decreases.

[0088] 8(A) is a cross-sectional view showing the wafer 11 when pre-treatment is performed on the adhesive layer 25. For example, a mask 38 is fixed to the surface (lower surface) of the support substrate 23 opposite to the surface (upper surface) to which the wafer 11 is fixed. The mask 38 has an opening 38a that passes through the mask 38 from top to bottom, and is fixed so that the opening 38a overlaps the defective device region 11c.

[0089] In addition, an energy applying unit 40 that applies energy to the adhesive layer 25 is disposed below the support substrate 23. The energy applying unit 40 applies energy to the adhesive layer 25 through the opening 38a of the mask 38. The type of energy applied to the adhesive layer 25 by the energy applying unit 40 is selected depending on the properties of the adhesive layer 25.

[0090] For example, when the adhesive layer 25 is an adhesive made of a thermoplastic resin or a tape including a thermally foamed layer, a heater is used as the energy application unit 40. Furthermore, a heat insulating member is used as the mask 38. Then, heat is applied from the energy application unit 40 to an area of ​​the support substrate 23 that overlaps with the opening 38a of the mask 38, and the heat of the support substrate 23 is conducted to the adhesive layer 25. As a result, the area of ​​the adhesive layer 25 that overlaps with the opening 38a of the mask 38 is partially heated.

[0091] Furthermore, when the adhesive layer 25 is an adhesive made of an ultraviolet-curable resin, a light source (lamp) that irradiates ultraviolet light is used as the energy application unit 40. Furthermore, a member that is transparent to ultraviolet light is used as the support substrate 23, and a member that is light-blocking to ultraviolet light is used as the mask 38. Then, ultraviolet light is irradiated from the energy application unit 40 onto the adhesive layer 25 through the opening 38a of the mask 38 and the support substrate 23. As a result, the ultraviolet light is partially irradiated onto the region of the adhesive layer 25 that overlaps with the opening 38a of the mask 38.

[0092] When energy is applied to the adhesive layer 25 from the energy application unit 40, the adhesive strength of the region of the adhesive layer 25 that overlaps with the defective device region 11c is partially reduced. This makes it easier to peel the defective device region 11c from the adhesive layer 25.

[0093] 8(B) is a cross-sectional view showing the wafer 11 when the defective device region 11c is being separated. After pre-processing the wafer 11 as necessary, the defective device region 11c is held and separated from the wafer 11. This causes the defective device region 11c to be peeled off from the adhesive layer 25 and cut out from the wafer 11.

[0094] When separating the defective device region 11c from the wafer 11, the separation of the defective device region 11c may be assisted by irradiating the wafer 11 or the support substrate 23 with ultrasonic waves. FIG. 9 is a cross-sectional view showing the ultrasonic wave irradiation unit 42.

[0095] The ultrasonic wave irradiation unit 42 includes a box-shaped container 44 formed in a rectangular parallelepiped shape. A liquid 46 such as pure water is stored in the container 44. An ultrasonic wave transmitter 48 that emits ultrasonic waves is also provided in the container 44.

[0096] The wafer 11 on which the modified layer 27 and the cracks 29 have been formed is placed in the container 44 so as to be immersed in the liquid 46. At this time, the wafer 11 is placed, for example, so that the support substrate 23 faces the ultrasonic transmitter 48. In this state, when the ultrasonic transmitter 48 is caused to emit ultrasonic waves, the ultrasonic waves propagate through the liquid 46 as a medium and reach the support substrate 23, and ultrasonic vibrations are applied to the support substrate 23.

[0097] Even if the wafer 11 is not sufficiently broken along the modified layer 27 and the crack 29, applying ultrasonic vibrations to the support substrate 23 will promote the breaking of the wafer 11 due to the vibration of the support substrate 23. Furthermore, the vibration of the support substrate 23 weakens the bond between the defective device region 11c and the adhesive layer 25. As a result, the defective device region 11c is more likely to be separated from the wafer 11. Note that ultrasonic waves may be applied only to a portion of the support substrate 23 that overlaps with the defective device region 11c.

[0098] In this way, the defective device region 11c is separated from the wafer 11. Then, a through-hole 11d penetrating the wafer 11 in the thickness direction is formed in the location of the defective device region 11c of the wafer 11 (see FIG. 8(B)).

[0099] The above describes, as an example, a method of breaking the wafer 11 along the modified layer 27 and the crack 29 formed by irradiation with the laser beam 32A. However, the laser processing performed on the wafer 11 is not limited to forming the modified layer 27 and the crack 29. For example, in the removal step, the defective device region 11c can also be separated from the wafer 11 by performing an ablation process on the wafer 11.

[0100] 10(A) is a cross-sectional view showing the wafer 11 to be irradiated with the laser beam 32B. When performing ablation processing on the wafer 11, a laser irradiation unit 30B is used to irradiate the wafer 11 with the laser beam 32B. The configuration of the laser irradiation unit 30B is the same as that of the laser irradiation unit 30A (see FIG. 4(A)).

[0101] However, the irradiation conditions of the laser beam 32B are set so that the region of the wafer 11 irradiated with the laser beam 32B is removed by ablation. Specifically, the wavelength of the laser beam 32B is set so that at least a portion of the laser beam 32B is absorbed by the wafer 11. In other words, the laser irradiation unit 30B irradiates the laser beam 32B with a wavelength that is absorbed by the wafer 11. In addition, other irradiation conditions of the laser beam 32B are also set so that the wafer 11 is appropriately ablated.

[0102] For example, the laser beam 32B is irradiated onto the front surface 11a of the wafer 11. Specifically, the wafer 11 is held by a chuck table (not shown) of a laser processing device so that the front surface 11a is exposed. Then, with the focal point of the laser beam 32B positioned on the street 13 of the wafer 11, the laser beam 32B is irradiated along the four streets 13 surrounding the defective device 15a. There is no limitation on the scanning path of the laser beam 32B. For example, the laser beam 32B is scanned along the path 34A or the path 34B shown in FIGS. 5(A) and 5(B).

[0103] 10(B) is a cross-sectional view showing the wafer 11 on which the grooves 31 are formed. When the laser beam 32B is irradiated along the four streets 13 surrounding the defective device 15a, the regions along the streets 13 on the front surface 11a side of the wafer 11 are removed by ablation. As a result, the grooves 31, which are rectangular in plan view, are formed along the streets 13 on the front surface 11a side of the wafer 11.

[0104] There is no limitation on the shape of the groove 31. For example, the groove 31 may be formed so that its width is constant in the thickness direction of the wafer 11, or so that its width increases toward the back surface 11b of the wafer 11 as shown in FIG.

[0105] Furthermore, when forming the grooves 31, the front surface 11a side of the wafer 11 may be covered with a protective film, and the laser beam 32B may be irradiated onto the wafer 11 through the protective film. For example, the protective film may be a resin tape or a film made of a water-soluble resin such as PVA (polyvinyl alcohol) or PEG (polyethylene glycol). If a protective film is formed on the front surface 11a side of the wafer 11, it is possible to prevent processing debris generated during the ablation process from adhering to the front surface 11a of the wafer 11, thereby avoiding contamination of the wafer 11 and the semiconductor device 15.

[0106] Alternatively, the wafer 11 may be etched by supplying plasma gas or etching liquid to the processing area (groove 31) processed by irradiation with the laser beam 32B. This expands the groove 31 and removes minute irregularities formed on the inner wall of the groove 31 by the ablation process.

[0107] When etching the wafer 11, it is preferable to form a mask that covers the front surface 11a side of the wafer 11. This mask has openings that expose the regions of the wafer 11 where the grooves 31 are formed. Then, plasmatized gas or etching liquid is supplied to the wafer 11 through the mask. This protects the semiconductor devices 15 formed on the front surface 11a side of the wafer 11.

[0108] There is no limitation on the material of the mask used in the etching process. For example, a photosensitive resin resist can be used as the mask. Alternatively, the aforementioned protective film (PVA, PEG, etc.) formed on the front surface 11a of the wafer 11 during irradiation with the laser beam 32B can also be used as the mask.

[0109] Next, the back surface 11b side of the wafer 11 is ground, thereby exposing the processing area (groove 31) processed by the irradiation of the laser beam 32B on the back surface 11b side of the wafer 11. When grinding the wafer 11, first, the wafer 11 is fixed to a support substrate. FIG. 11(A) is a cross-sectional view showing the wafer 11 fixed to the support substrate 23. When grinding the back surface 11b side of the wafer 11, the front surface 11a side of the wafer 11 is fixed to the support substrate 23 via an adhesive layer 25.

[0110] Next, the wafer 11 is ground by a grinding device 2 (see FIG. 2). Specifically, the back surface 11b of the wafer 11 is ground by bringing a grinding wheel 16 into contact with the back surface 11b of the wafer 11. The wafer 11 is then ground and thinned until the grooves 31 are exposed on the back surface 11b of the wafer 11.

[0111] 11(B) is a cross-sectional view showing wafer 11 after grinding. When groove 31 is exposed on the back surface 11b side of wafer 11, defective device region 11c is separated from wafer 11. Thereafter, as described above, defective device region 11c is separated from wafer 11, and through-hole 11d is formed in wafer 11 (see FIGS. 8(A), 8(B), and 9).

[0112] In the removing step, the wafer 11 may be cut by irradiation with a laser beam. Specifically, a kerf (cut) extending from the front surface 11a to the back surface 11b of the wafer 11 is formed along the street 13 by ablation processing.

[0113] 12(A) is a cross-sectional view showing the wafer 11 to be irradiated with the laser beam 32C. A laser irradiation unit 30C that irradiates the wafer 11 with the laser beam 32C is used to cut the wafer 11. The configuration of the laser irradiation unit 30C is the same as that of the laser irradiation unit 30A (see FIG. 4(A)).

[0114] However, the irradiation conditions of the laser beam 32C are set so that the region from the front surface 11a to the back surface 11b of the wafer 11 is removed by ablation. Specifically, the wavelength of the laser beam 32C is set so that at least a portion of the laser beam 32C is absorbed by the wafer 11. In other words, the laser irradiation unit 30C irradiates the laser beam 32C with a wavelength that is absorbed by the wafer 11. In addition, other irradiation conditions of the laser beam 32C are also set so that the region from the front surface 11a to the back surface 11b of the wafer 11 is removed.

[0115] When the wafer 11 is irradiated with the laser beam 32C, first, a protective member 33 such as tape is attached to the wafer 11. For example, when the front surface 11a of the wafer 11 is irradiated with the laser beam 32C, tape is attached as the protective member 33 to the back surface 11b of the wafer 11.

[0116] Next, the front surface 11a of the wafer 11 is irradiated with a laser beam 32C. Specifically, with the focal point of the laser beam 32C positioned on the street 13 of the wafer 11, the laser beam 32C is irradiated along the four streets 13 surrounding the defective device 15a. There is no limitation on the scanning path of the laser beam 32C. For example, the laser beam 32C is scanned along a path 34A or a path 34B shown in FIGS. 5(A) and 5(B).

[0117] When the laser beam 32C is irradiated along the street 13 surrounding the defective device 15a, the wafer 11 is removed along the street 13. As a result, a kerf 35 extending from the front surface 11a to the back surface 11b is formed in the wafer 11 along the street 13. As a result, the defective device region 11c is separated from the wafer 11.

[0118] If it is difficult to form a kerf 35 reaching the back surface 11b of the wafer 11 by scanning the laser beam 32C only once along the streets 13, the laser beam 32C may be scanned multiple times along each street 13. Thereafter, the defective device region 11c is separated from the wafer 11 as described above, and a through-hole 11d is formed in the wafer 11 (see FIGS. 8(A), 8(B), and 9).

[0119] After the defective device region 11c is separated from the wafer 11, the wafer 11 is fixed to a support substrate 23. Fig. 12(B) is a cross-sectional view showing the wafer 11 fixed to the support substrate 23. After a kerf 35 is formed in the wafer 11 and the defective device region 11c is separated, the support substrate 23 is fixed to the front surface 11a side of the wafer 11 via an adhesive layer 25. Thereafter, the protective member 33 is peeled off and removed from the back surface 11b side of the wafer 11.

[0120] In the removal step, the wafer 11 can also be processed by a laser beam (aqua laser) irradiated through a liquid. Fig. 13(A) is a cross-sectional view showing the wafer 11 irradiated with a laser beam 32C through a liquid column 50.

[0121] The laser irradiation unit 30C may have a built-in injection unit (nozzle) that injects liquid toward the wafer 11. In this case, liquid is continuously supplied from the injection unit to the wafer 11, thereby forming a liquid column 50 that extends from the laser irradiation unit 30C to the wafer 11. The liquid column 50 is a column made of flowing liquid, and functions as a light guide path for propagating the laser beam 32C. For example, water is injected from the injection unit to form a water column.

[0122] The wafer 11 is held by a holding table 52. The upper surface of the holding table 52 forms a flat holding surface 52a that holds the wafer 11. The holding table 52 is also provided with openings 52b that penetrate the holding table 52 from top to bottom. The openings 52b are formed in a rectangular shape in a plan view corresponding to the four streets 13 that surround the semiconductor device 15. The wafer 11 is placed on the holding table 52 so that the four streets 13 that surround the defective device 15a overlap with the openings 52b, respectively.

[0123] Then, liquid is ejected from laser irradiation unit 30C to form liquid column 50, and laser beam 32C is irradiated from laser irradiation unit 30C. At this time, the focal point of laser beam 32C is positioned inside liquid column 50. Laser beam 32C is then irradiated onto wafer 11 via liquid column 50.

[0124] As described above, when the laser beam 32C is irradiated onto the liquid column 50, the laser beam 32C can be directed onto the street 13 of the wafer 11 without strictly controlling the height position of the focal point of the laser beam 32C. In addition, debris generated by the laser processing is washed away by the liquid.

[0125] Then, the laser beam 32C is scanned along the street 13 together with the liquid column 50. As a result, a kerf 35 is formed in the wafer 11 along the street 13, and the defective device region 11c is separated from the wafer 11. The liquid ejected from the laser irradiation unit 30C is discharged through an opening 52b provided in the holding table 52.

[0126] Thereafter, the wafer 11 is fixed to a support substrate. Fig. 13(B) is a cross-sectional view showing the wafer 11 fixed to the support substrate 23. After a kerf 35 is formed in the wafer 11 and the defective device region 11c is separated, the support substrate 23 is fixed to the front surface 11a side of the wafer 11 via an adhesive layer 25.

[0127] Alternatively, etching may be performed by supplying plasma gas or etching solution to the processed region (kerf 35) processed by irradiation with laser beam 32C, thereby expanding kerf 35 and removing minute irregularities formed on the inner wall of kerf 35 by ablation processing.

[0128] Although the above describes a method for separating the defective device region 11c from the wafer 11 by laser processing, methods other than laser processing can also be used to separate the defective device region 11c. For example, so-called plasma dicing, in which the wafer 11 is cut by plasma etching, can also be used.

[0129] When performing plasma dicing, first, a support substrate 23 is fixed to the front surface 11a of the wafer 11 (see FIG. 4(A)). Then, a mask for plasma etching is formed on the back surface 11b of the wafer 11.

[0130] 14(A) is a cross-sectional view showing the wafer 11 on which a mask layer 37 is formed. The mask layer 37 is made of a material that functions as a mask for plasma etching, and is formed so as to cover the entire back surface 11b of the wafer 11. For example, the mask layer 37 can be made of a resist made of a photosensitive resin, or a water-soluble resin such as PVA or PEG.

[0131] Next, the mask layer 37 is removed in areas that overlap with the four streets 13 surrounding the defective device 15a. For example, the mask layer 37 is removed along the streets 13 by irradiating the mask layer 37 with a laser beam 56 from a laser irradiation unit 54. The irradiation conditions of the laser beam 56 are set so that the mask layer 37 is removed by ablation when the laser beam 56 is irradiated onto the mask layer 37.

[0132] When the mask layer 37 is irradiated with a laser beam 56 along the four streets 13 surrounding the defective device 15a, rectangular openings that expose the four streets 13 are formed in the mask layer 37. This patterning the mask layer 37 forms a mask 39 (see FIG. 14(B)) for plasma etching.

[0133] Next, the wafer 11 is subjected to plasma etching using the mask 39. For plasma etching of the wafer 11, for example, the above-mentioned plasma processing apparatus is used.

[0134] 14(B) is a cross-sectional view showing wafer 11 being subjected to plasma etching. When plasma etching is performed, etching gas 58 in the form of plasma is supplied to wafer 11 through openings in mask 39. As a result, etching is performed on the area of ​​wafer 11 along street 13 surrounding defective device 15a, and a groove is formed on back surface 11b of wafer 11.

[0135] 14(C) is a cross-sectional view showing the wafer 11 after plasma etching. As the etching progresses, the groove formed on the back surface 11b of the wafer 11 reaches the front surface 11a, and a kerf 35 extending from the front surface 11a to the back surface 11b of the wafer 11 is formed along the street 13, and the defective device region 11c is separated from the wafer 11. Thereafter, the defective device region 11c is separated from the wafer 11, and a through-hole 11d is formed in the wafer 11 (see FIGS. 8(A), 8(B), and 9).

[0136] The plasma etching may be performed by supplying plasmatized gas 58 to the front surface 11a side of the wafer 11. In this case, a mask 39 is formed on the front surface 11a side of the wafer 11 before the wafer 11 is fixed to the support substrate 23. Then, gas 58 is supplied to the wafer 11 through the mask 39, and a groove is formed on the front surface 11a side of the wafer 11. When this groove reaches the back surface 11b, a kerf 35 is formed, and the defective device region 11c is separated from the wafer 11. Then, the support substrate 23 is fixed to the front surface 11a side of the wafer 11.

[0137] Through the above steps, the defective device region 11c is separated from the wafer 11, and through holes 11d are formed in the wafer 11. As a result, a wafer 11 that does not include defective devices 15a is obtained, as shown in FIG. 3(B).

[0138] Next, a device chip is prepared that includes a non-defective semiconductor device 15 of the same type as the semiconductor device 15 determined to be defective (defective device 15a) and has a size that can be fitted into the through-hole 11d. For manufacturing the device chip, for example, a wafer having the same structure as the wafer 11 is used. Fig. 15(A) is a perspective view showing a wafer 51 used for preparing the device chip.

[0139] The wafer 51 is made of the same material as the wafer 11 and has a front surface (first surface) 51a and a back surface (second surface) 51b. The wafer 51 is divided into a plurality of regions by a plurality of streets (planned division lines) 53 arranged in a grid pattern so as to intersect with one another. A semiconductor device 55 is formed in each of the plurality of regions divided by the streets 53 on the front surface 51a side of the wafer 51.

[0140] The semiconductor device 55 has the same function as the semiconductor device 15 shown in Fig. 1(A) etc. The structure of the semiconductor device 55 is the same as that of the semiconductor device 15, and an electrode (via electrode, through electrode) 57 (see Fig. 17(A)) is connected to the semiconductor device 55. The structure and material of the electrode 57 are the same as those of the electrode 19 shown in Fig. 1(B) etc.

[0141] A plurality of device chips, each including a semiconductor device 55, are manufactured by dividing the wafer 51 along the streets 53. The wafer 51 is divided by, for example, the above-mentioned laser processing or plasma etching.

[0142] A cutting device can also be used to divide the wafer 51. The cutting device includes a chuck table that holds the wafer 51 and a cutting unit that cuts the wafer 51 held by the chuck table. An annular cutting blade is attached to the cutting unit. The cutting blade is rotated to cut into the wafer 51, thereby dividing the wafer 51 along the streets 53. As a result, a plurality of device chips each having a semiconductor device 55 are obtained.

[0143] 15(B) is a perspective view showing the wafer 51 divided into a plurality of device chips 59. Before or after dividing the wafer 51, the plurality of semiconductor devices 55 formed on the wafer 51 are inspected to determine whether each of the semiconductor devices 55 is a non-defective product. Then, from the plurality of device chips 59 obtained by dividing the wafer 51, device chips 59 including semiconductor devices 55 determined to be defective are excluded.

[0144] This results in device chips 59 each including a semiconductor device 55 identical to the non-defective semiconductor device 15 (see FIG. 1(A) etc.) formed on the wafer 11. That is, the device chip 59 includes a non-defective semiconductor device 55 having the same function as the defective device 15a (see FIG. 1(A) etc.) (a semiconductor device 55 having the function that the defective device 15a should originally have).

[0145] There is no limitation on the timing for preparing the device chips 59. For example, the preparation of the wafer 51 and the inspection of the semiconductor devices 55 are carried out at the same timing as the preparation of the wafer 11 and the inspection of the semiconductor devices 15, and then the device chips 59 are manufactured by dividing the wafer 51.

[0146] Next, the device chips 59 are fitted into the through holes 11d of the wafer 11 (fitting step). Fig. 16 is a perspective view showing the wafer 11 in the fitting step.

[0147] When the front surface 11a side (semiconductor device 15 side) of the wafer 11 is fixed to the support substrate 23, the device chip 59 is positioned so that the surface side (front surface side) on which the semiconductor devices 55 are formed faces the support substrate 23. Then, the device chip 59 is fitted into the through-hole 11d of the wafer 11.

[0148] 17(A) is a cross-sectional view showing the wafer 11 in which the device chip 59 is embedded. The device chip 59 is embedded in the through-hole 11d so as to come into contact with the adhesive layer 25 exposed in the through-hole 11d. As a result, the device chip 59 is fixed to the support substrate 23 via the adhesive layer 25.

[0149] In addition, when the wafer 11 is temporarily fixed to the support substrate 23 by the adhesive layer 25 and the bond between the wafer 11 and the support substrate 23 is weak, after the device chip 59 is fitted into the through-hole 11d, a process (main fixing process) is performed to firmly fix the wafer 11 to the support substrate 23. As a result, the wafer 11 and the device chip 59 are firmly fixed to the support substrate 23 via the adhesive layer 25.

[0150] For example, if the adhesive layer 25 is an adhesive made of a thermosetting resin, the thermosetting resin is cured by performing a heat treatment at a higher temperature or for a longer period than during temporary fixing, thereby strengthening the bond between the wafer 11 and the support substrate 23. Also, if the adhesive layer 25 is an adhesive made of an ultraviolet-curable resin, the ultraviolet-curable resin is subjected to a heat treatment, thereby strengthening the bond between the wafer 11 and the support substrate 23. Furthermore, if the adhesive layer 25 is a thermocompression sheet, the wafer 11 and the support substrate 23 are pressed against the thermocompression sheet while performing a heat treatment at a higher temperature or for a longer period than during temporary fixing, thereby strengthening the bond between the wafer 11 and the support substrate 23.

[0151] Furthermore, if the wafer 11 is temporarily fixed to the support substrate 23 using an adhesive layer 25 with weak adhesive strength in the removal step, the wafer 11 and the support substrate 23 may be separated temporarily before the fitting step, and the wafer 11 may be re-fixed to the support substrate 23 using another adhesive layer with stronger adhesive strength than the adhesive layer 25.

[0152] 17B is a plan view showing the through-hole 11d. In the above-mentioned removal step, the through-hole 11d is formed to be larger than the device chip 59. Specifically, the length L of the through-hole 11d in the first direction (the left-right direction on the paper surface) is A1 is the length L of the device chip 59 in the first direction B1 Furthermore, the length L of the through-hole 11d in the second direction (the direction perpendicular to the first direction, the vertical direction on the paper) is larger than A2 is the length L of the device chip 59 in the second direction B2 Therefore, when the device chip 59 is fitted into the through-hole 11d, a gap 61 is formed between the wafer 11 and the device chip 59 so as to surround the device chip 59.

[0153] In a subsequent process (a resin filling step described below), the gap 61 is filled with resin. Therefore, it is preferable that the width of the gap 61 (the distance between the inner wall of the through-hole 11d and the side surface of the device chip 59) be at least a certain size. For example, the size of the through-hole 11d or the device chip 59 is adjusted so that the width of the gap 61 is at least 2 μm, preferably at least 5 μm, and more preferably at least 10 μm.

[0154] The specific dimensions of the through hole 11d can be set appropriately taking into consideration the positions of the semiconductor devices 15, 55, etc. For example, on the front surface 11a side of the wafer 11, the distance between the end (inner wall) of the through hole 11d and the end of the semiconductor device 15 is set to 2 μm or more, preferably 5 μm or more. Furthermore, on the front surface 11a side of the wafer 11, the end of the through hole 11d may be positioned closer to the semiconductor device 15 than the center in the width direction of the street 13. Furthermore, when the inner wall of the through hole 11d is inclined with respect to the thickness direction of the wafer 11 as shown in FIG. 17(A), a portion of the region of the through hole 11d on the back surface 11b side of the wafer 11 may overlap a portion of the semiconductor device 15 formed on the wafer 11.

[0155] There are no specific limitations on the dimensions of the device chip 59 as long as the device chip 59 can be fitted into the through-hole 11d. For example, on the front surface side of the device chip 59, the distance between the end of the semiconductor device 55 and the end of the device chip 59 is set to be equal to or less than half the width of the street 13 set on the wafer 11.

[0156] In the embedding step, the device chip 59 with the adhesive layer attached thereto may be embedded in the through-hole 11d instead of fixing the device chip 59 to the adhesive layer 25. Specifically, the adhesive layer 25 exposed inside the through-hole 11d may be removed by a process such as plasma etching or wet etching (chemical solution treatment), and then the device chip 59 with the adhesive layer attached thereto may be fixed to the support substrate 23 via the adhesive layer.

[0157] 18(A) is a cross-sectional view showing the wafer 11 when plasma etching is performed on the adhesive layer 25. For example, by supplying plasmatized gas (etching gas) 60 to the rear surface 11b side of the wafer 11, the area of ​​the adhesive layer 25 that overlaps with the through-hole 11d is removed.

[0158] 18(B) is a cross-sectional view showing the wafer 11 in a state where a portion of the adhesive layer 25 has been removed. When the region of the adhesive layer 25 that overlaps with the through-hole 11d is removed, the region of the upper surface of the support substrate 23 that overlaps with the through-hole 11d is exposed. When plasma etching is performed on the wafer 11, a mask that exposes the through-hole 11d may be formed on the back surface 11b of the wafer 11.

[0159] Next, the device chip 59 with the adhesive layer attached is fitted into the through-hole 11d. Figure 18(C) is a cross-sectional view showing the wafer 11 with the device chip 59 with the adhesive layer 63 attached fitted in. The adhesive layer 63 is provided on the front surface side (semiconductor device 55 side) of the device chip 59. An example of the material for the adhesive layer 63 is the same as that of the adhesive layer 25. The device chip 59 is fixed via the adhesive layer 63 to the upper surface of the support substrate 23 exposed inside the through-hole 11d.

[0160] After the device chip 59 is fitted into the through-hole 11d, a permanent fixing process is performed on the adhesive layers 25, 63, as necessary. As a result, the wafer 11 and the device chip 59 are firmly fixed to the support substrate 23 via the adhesive layers 25, 63.

[0161] Next, resin is filled into the gap 61 between the wafer 11 and the device chip 59 (resin filling step). Fig. 19(A) is a cross-sectional view showing the wafer 11 in the resin filling step.

[0162] In the resin filling step, resin 65 is formed on the back surface 11b side of the wafer 11. The resin 65 is formed by applying a liquid resin such as an epoxy resin to the back surface 11b side of the wafer 11 and curing it. However, there are no limitations on the material of the resin 65.

[0163] When the liquid resin is applied to the back surface 11b side of the wafer 11, part of the liquid resin flows into the gap 61 (see Figures 17(A), 17(B), etc.) between the wafer 11 and the device chip 59, filling the gap 61. When the liquid resin is cured in this state, the wafer 11 and the device chip 59 are bonded via the resin 65, and the device chip 59 is fixed to the wafer 11.

[0164] Next, the resin 65 formed outside the gap 61 is ground (resin grinding step). In the resin grinding step, the resin 65 formed on the back surface 11b side of the wafer 11 is removed by grinding. For example, a grinding device 2 (see FIG. 2) is used to grind the resin 65.

[0165] 19(B) is a cross-sectional view showing the wafer 11 in the resin grinding step. For example, in the resin grinding step, the resin 65 formed outside the gap 61 is removed by grinding, and the back surface 11b side of the wafer 11 is ground. Then, the wafer 11 is thinned until the electrodes 19 and 57 are exposed on the back surface 11b side of the wafer 11.

[0166] However, there is no limitation on the method for exposing the electrodes 19, 57. For example, after grinding the resin 65 until the back surface 11b of the wafer 11 is exposed in the resin grinding step, the electrodes 19, 57 may be exposed by performing an etching process such as plasma etching or wet etching on the back surface 11b of the wafer 11. In this case, it is possible to prevent the grinding wheel 16 (see FIG. 2) from coming into contact with the electrodes 19, 57 and causing metal contained in the electrodes 19, 57 to scatter.

[0167] Through the above steps, a wafer 11 is obtained that has electrodes 19, 57 exposed on the back surface 11b side. This makes it possible to connect the semiconductor devices 15, 55 to semiconductor devices (not shown) included in another wafer that is stacked on the back surface 11b side of the wafer 11 via the electrodes 19, 57. That is, the wafer manufacturing method according to this embodiment manufactures a wafer 11 that can be used to form stacked wafers.

[0168] Next, a specific example of a method for manufacturing a device chip (stacked device chip) having a plurality of stacked semiconductor devices using the above-mentioned wafer 11 will be described. When manufacturing a stacked device chip, first, a stacked wafer having a plurality of stacked wafers is formed (wafer stacking step). Figure 20 is a cross-sectional view showing a stacked wafer 79.

[0169] In the wafer stacking step, the wafer 11 (first wafer) after the resin grinding step and another wafer 71 (second wafer) prepared in the wafer preparation step described above are used. The configuration of the wafer 71 is the same as that of the wafer 11.

[0170] Specifically, the wafer 71 is made of the same material as the wafer 11, and has a front surface (first surface) 71a and a back surface (second surface) 71b. The wafer 71 is divided into a plurality of rectangular regions by a plurality of streets (planned division lines) 73 arranged in a grid pattern so as to intersect with one another. A semiconductor device 75 is formed in each of the plurality of regions divided by the streets 73 on the front surface 71a side of the wafer 71.

[0171] The structure of the semiconductor device 75 is the same as that of the semiconductor device 15. An electrode (via electrode, through electrode) 77 is connected to the semiconductor device 75. The structure and material of the electrode 77 are the same as those of the electrode 19.

[0172] The wafer 71 is stacked on the wafer 11. For example, the wafer 71 is bonded to the wafer 11 so that the front surface 71a faces the back surface 11b of the wafer 11. There is no limitation on the method for bonding the wafer 11 and the wafer 71. For example, the wafer 11 and the wafer 71 are bonded by direct bonding. Specifically, the back surface 11b of the wafer 11 and the front surface 71a of the wafer 71 are bonded by surface activated bonding.

[0173] However, the wafer 11 and the wafer 71 may be bonded together by indirect bonding. For example, the wafer 11 and the wafer 71 may be bonded together by stacking the wafer 71 on the wafer 11 via a permanent adhesive.

[0174] If the plurality of semiconductor devices 75 formed on the wafer 71 includes defective devices, the wafer 71 is subjected to a grinding step, a removing step, a fitting step, a resin filling step, and a resin grinding step before or after the wafer 71 is stacked on the wafer 11. As a result, the defective devices are removed from the wafer 71, and device chips 59 including non-defective semiconductor devices 55 are fitted into the wafer 71.

[0175] The wafer 11 and the wafer 71 are bonded together so that the streets 13 and the streets 73 overlap, and so that the semiconductor devices 15 and 55 included in the wafer 11 overlap the semiconductor devices 75 and 55 included in the wafer 71. As a result, the semiconductor devices 15 and 55 included in the wafer 11 and the semiconductor devices 75 and 55 included in the wafer 71 are connected via the electrodes 19 and 57.

[0176] In this way, a stacked wafer 79 is formed, which includes the wafer 11 and the wafer 71 stacked on top of each other. Note that in the wafer stacking step, a plurality of wafers 71 may be stacked on the wafer 11. For example, another wafer 71 may be stacked on the wafer 71 stacked on the wafer 11. In this case, the grinding step, removing step, embedding step, resin filling step, and resin grinding step are performed on each of the plurality of wafers 71 stacked on the wafer 11. As a result, a stacked wafer 79 including three or more layers of wafers is obtained.

[0177] Next, stacked device chips each including a plurality of stacked semiconductor devices are formed by dividing the stacked wafer 79 along the streets 13 and 73 (dividing step). Fig. 21(A) is a cross-sectional view showing the stacked wafer 79 in the dividing step.

[0178] In the dividing step, the stacked wafers 79 are cut by, for example, a cutting device. The cutting device includes a chuck table that holds the stacked wafers 79 and a cutting unit that cuts the stacked wafers 79 held by the chuck table. The cutting unit includes a cylindrical spindle that is rotated by a rotation drive source such as a motor. An annular cutting blade 62 for cutting the stacked wafers 79 is attached to the tip of the spindle.

[0179] For example, a hub-type cutting blade (hub blade) is used as the cutting blade 62. A hub blade is composed of an annular base made of metal or the like and an annular cutting edge formed along the outer periphery of the base. The cutting edge of the hub blade is composed of an electroformed grinding stone in which abrasive grains made of diamond or the like are fixed with a bonding material such as nickel plating.

[0180] A washer-type cutting blade (washer blade) can also be used as the cutting blade 62. A washer blade is configured with an annular cutting edge in which abrasive grains are fixed by a binder made of metal, ceramics, resin, or the like.

[0181] The stacked wafers 79 are divided by rotating the cutting blade 62 to cut into the stacked wafers 79. Specifically, with the lower end of the cutting blade 62 positioned below the front surface 11a of the wafer 11 (the upper surface of the adhesive layer 25), the cutting blade 62 and the stacked wafers 79 are moved relatively in the horizontal direction while rotating the cutting blade 62, thereby causing the cutting blade 62 to cut into the stacked wafers 79 along the streets 13, 73. When the stacked wafers 79 have been cut along all the streets 13, 73, the stacked wafers 79 are divided into a plurality of stacked device chips.

[0182] 21(B) is a cross-sectional view showing the stacked wafer 79 divided into a plurality of stacked device chips 81. Each stacked device chip 81 includes one semiconductor device 15 or one semiconductor device 55 (first semiconductor device) included in the wafer 11, and one semiconductor device 75 or one semiconductor device 55 (second semiconductor device) included in the wafer 71. The first semiconductor device and the second semiconductor device are stacked on each other and connected via electrodes 19 or 57.

[0183] As described above, in the wafer manufacturing method according to this embodiment, the defective device region 11c is removed from the wafer 11, and the device chip 59 having the non-defective semiconductor device 15 is fitted into the space (removed region) formed by removing the defective device region 11c. This makes it possible to manufacture a wafer 11 that does not contain any defective devices 15a. Furthermore, by stacking wafers 11 that do not contain any defective devices 15a to form a stacked wafer 79, and then dividing the stacked wafer 79, it is possible to manufacture stacked device chips 81 that do not contain any defective devices 15a. As a result, a decrease in the yield of the stacked device chips 81 is suppressed.

[0184] (Embodiment 2) In the first embodiment, an example in which the defective device region 11c is separated by irradiation with a laser beam in the removal step has been described, but other methods may be used to separate the defective device region 11c. In this embodiment, a method in which the defective device region 11c is separated by a crushing process that crushes the wafer 11 in the removal step after the wafer preparation step and the grinding step (see FIG. 2) have been performed will be described.

[0185] The crushing process used in this embodiment is not limited as long as it can process the wafer 11. Examples of crushing processes that can be used to process the wafer 11 include sandblasting, water jet processing, and drilling.

[0186] 22(A) is a cross-sectional view showing a wafer 11 in which grooves 93 are formed by sandblasting. Sandblasting uses a sandblasting unit 72 that sprays abrasives 74. For example, the sandblasting unit 72 includes a compressor that compresses and discharges gas such as air, and a blast gun that sprays abrasives 74 together with the compressed gas. The abrasives 74 sprayed from the sandblasting unit 72 collide with the wafer 11, thereby processing the wafer 11.

[0187] When performing the crushing process, first, a protective layer 91 is formed on the wafer 11. For example, when processing the front surface 11a side of the wafer 11, the front surface 11a side of the wafer 11 is covered with the protective layer 91 to protect the semiconductor devices 15. There are no restrictions on the material of the protective layer 91, and for example, a water-soluble resin such as PVA or PEG can be used. Furthermore, if the semiconductor devices 15 are unlikely to be damaged by the crushing process, the formation of the protective layer 91 may be omitted.

[0188] Next, the wafer 11 is held by the holding table 70. The upper surface of the holding table 70 forms a flat holding surface 70a that holds the wafer 11. For example, the wafer 11 is placed on the holding table 70 so that the front surface 11a side is exposed upward and the back surface 11b side faces the holding surface 70a.

[0189] Then, abrasive material 74 is sprayed from sandblasting unit 72 along the four streets 13 surrounding defective device 15a. As a result, strip-shaped grooves 93 are formed along the streets 13 on the front surface 11a side of wafer 11. These grooves 93 are formed in a rectangular shape in plan view so as to surround defective device 15a.

[0190] FIG. 22(B) is a cross-sectional view showing a wafer 11 in which a groove 93 is formed by water jet machining. A water jet unit 76 that sprays a liquid 78 such as water is used for water jet machining. The water jet unit 76 has a nozzle that sprays the liquid 78 pressurized by a pump. The liquid 78 may contain abrasive grains. The liquid 78 sprayed from the water jet unit 76 collides with the wafer 11, thereby processing the wafer 11.

[0191] Specifically, the liquid 78 is jetted from the water jet unit 76 along the four streets 13 surrounding the defective device 15a. As a result, a strip-shaped groove 93 is formed along the streets 13 on the front surface 11a side of the wafer 11. The groove 93 is formed in a rectangular shape in a plan view so as to surround the defective device 15a.

[0192] 22(C) is a cross-sectional view showing the wafer 11 in which a groove 93 is formed by drilling. A drill unit 80 to which a rod-shaped drill bit 82 is attached is used for drilling. The drill unit 80 includes a rotational drive source such as a motor that rotates the drill bit 82 attached to the drill unit 80. The wafer 11 is machined by bringing the tip of the drill bit 82 into contact with the wafer 11 while rotating the drill bit 82.

[0193] Specifically, first, the rotating drill bit 82 is brought into contact with an area of ​​the wafer 11 that overlaps with the street 13, and a cylindrical groove is formed in the wafer 11. Next, the holding table 70 or the drill bit 82 is moved along the street 13. Note that the amount of movement at this time is set to be less than the diameter of the cylindrical groove formed in the wafer 11. Thereafter, a new groove is formed in the wafer 11 with the drill bit 82. As a result, the groove already formed in the wafer 11 and the newly formed groove are connected.

[0194] The above procedure is repeated to form multiple grooves along the four streets 13 surrounding the defective device 15a. As a result, a strip-shaped groove 93 is formed along the streets 13 on the front surface 11a side of the wafer 11. This groove 93 is composed of multiple cylindrical grooves formed to connect to each other.

[0195] As described above, by performing the fracturing process along the street 13 surrounding the defective device 15a, a groove 93 is formed in the wafer 11. Thereafter, the back surface 11b side of the wafer 11 is ground to expose the processed region (groove 93) processed by the fracturing process on the back surface 11b side of the wafer 11.

[0196] When grinding the wafer 11, first, the wafer 11 is fixed to the support substrate 23. Fig. 23(A) is a cross-sectional view showing the wafer 11 fixed to the support substrate 23. When grinding the back surface 11b side of the wafer 11, the front surface 11a side of the wafer 11 is fixed to the support substrate 23 via an adhesive layer 25.

[0197] Next, the wafer 11 is ground by the grinding device 2 (see FIG. 2). Specifically, the back surface 11b of the wafer 11 is ground by bringing the grinding wheel 16 into contact with the back surface 11b of the wafer 11. Then, the wafer 11 is ground and thinned until the grooves 93 are exposed on the back surface 11b of the wafer 11.

[0198] 23(B) is a cross-sectional view showing the wafer 11 after grinding. When the grooves 93 are exposed on the back surface 11b side of the wafer 11, the defective device region 11c is separated from the wafer 11. Thereafter, the defective device region 11c is separated from the wafer 11 by the same procedure as in embodiment 1, and through-holes 11d are formed in the wafer 11 (see FIGS. 8(A), 8(B), and 9).

[0199] In the removing step, the defective device region 11c may be separated by forming through-holes that penetrate the wafer 11 by a crushing process. Specifically, through-holes that reach the back surface 11b of the wafer 11 from the front surface 11a are formed along the streets 13 by the crushing process.

[0200] 24(A) is a cross-sectional view showing a wafer 11 in which through-holes 95 are formed by sandblasting. When the through-holes 95 are formed by crushing, openings 70b are provided in the holding table 70, which penetrate the holding table 70 from top to bottom. The openings 70b are formed in a rectangular shape in a plan view corresponding to the four streets 13 surrounding the semiconductor device 15. The wafer 11 is then placed on the holding table 70 so that the four streets 13 surrounding the defective device 15a overlap with the openings 70b, respectively.

[0201] Next, abrasive material 74 is sprayed from a sandblasting unit 72 along the four streets 13 surrounding the defective device 15a. The spraying conditions of the abrasive material 74 are set so that holes penetrating the wafer 11 from the front surface 11a to the back surface 11b are formed in the area of ​​the wafer 11 where the abrasive material 74 collides.

[0202] Therefore, when the abrasive 74 is sprayed along the streets 13, a strip-shaped through-hole 95 extending from the front surface 11a to the back surface 11b is formed in the wafer 11 along the streets 13. The through-hole 95 is formed in a rectangular shape in a plan view so as to surround the defective device 15a. As a result, the defective device region 11c is separated from the wafer 11.

[0203] 24(B) is a cross-sectional view showing a wafer 11 in which a through-hole 95 is formed by water jet processing. When forming the through-hole 95 by water jet processing, a liquid 78 is sprayed from a water jet unit 76 along four streets 13 surrounding the defective device 15a. The spraying conditions for the liquid 78 are set so that a hole penetrating the wafer 11 from the front surface 11a to the back surface 11b is formed in the region of the wafer 11 where the liquid 78 collides.

[0204] Therefore, when the liquid 78 is sprayed along the streets 13, a strip-shaped through-hole 95 extending from the front surface 11a to the back surface 11b of the wafer 11 is formed along the streets 13. The through-hole 95 is formed in a rectangular shape in a plan view so as to surround the defective device 15a. As a result, the defective device region 11c is separated from the wafer 11.

[0205] 24(C) is a cross-sectional view showing the wafer 11 in which a through-hole 95 is formed by drilling. When forming the through-hole 95 by drilling, first, the drill bit 82 is rotated and brought into contact with the wafer 11 to form a cylindrical hole that penetrates the wafer 11 from the front surface 11a to the back surface 11b.

[0206] Thereafter, the same procedure is repeated to form a plurality of holes along the four streets 13 surrounding the defective device 15a. Each of the plurality of holes is formed so as to connect to holes already formed in the wafer 11. As a result, a strip-shaped through-hole 95 extending from the front surface 11a to the back surface 11b is formed in the wafer 11 along the streets 13, and the defective device region 11c is separated from the wafer 11.

[0207] When sandblasting (see FIG. 24(A)) is performed, abrasive 74 that passes through through-hole 95 in wafer 11 is discharged through opening 70b in holding table 70. Similarly, when water jet processing (see FIG. 24(B)) is performed, liquid 78 that passes through through-hole 95 in wafer 11 is discharged through opening 70b in holding table 70. This prevents abrasive 74 and liquid 78 from colliding with holding surface 70a of holding table 70 and damaging holding table 70.

[0208] Furthermore, when sandblasting (see FIG. 24(C)) is performed, the tip of the drill bit 82 is inserted into the opening 70b of the holding table 70. This prevents the drill bit 82 from coming into contact with the holding table 70 and damaging the holding table 70.

[0209] 24(A), 24(B), and 24(C) show the wafer 11 being processed from the front surface 11a side, the wafer 11 may also be processed from the back surface 11b side. That is, the abrasive 74 or the liquid 78 may be collided with the back surface 11b side of the wafer 11, or the drill bit 82 may be brought into contact with the back surface 11b side of the wafer 11.

[0210] Next, the protective layer 91 is removed from the wafer 11, and the defective device region 11c is separated from the wafer 11. Thereafter, the wafer 11 is fixed to the support substrate 23. FIG. 25 is a cross-sectional view showing the wafer 11 fixed to the support substrate 23. For example, the front surface 11a side of the wafer 11 is fixed to the support substrate 23 via an adhesive layer 25.

[0211] The wafer 11 in which the through-holes 11d are formed by the crushing process may be subjected to an etching process. For example, plasma etching is performed on the inside of the through-holes 11d by supplying a plasma gas to the through-holes 11d of the wafer 11. Alternatively, wet etching is performed on the inside of the through-holes 11d by supplying an etching solution to the through-holes 11d of the wafer 11.

[0212] 26 is a cross-sectional view showing wafer 11 undergoing plasma etching. When plasmatized etching gas 84 (etching gas) is supplied to wafer 11, plasma etching is performed on the inner walls of through-holes 11d. This increases the size of through-holes 11d. Furthermore, minute irregularities formed on the inner walls of through-holes 11d by the crushing process are removed by plasma etching.

[0213] The area of ​​the wafer 11 to be crushed is appropriately set so that through-holes 11d of a desired size are formed. Fig. 27(A) is a plan view showing an area (area to be processed) 97A to be processed by sandblasting or water jet processing. Fig. 27(B) is a plan view showing an area (area to be processed) 97B to be processed by drilling. In Figs. 27(A) and 27(B), patterns are applied to areas 97A and 97B.

[0214] When processing the wafer 11 by sandblasting, for example, the abrasive 74 is sprayed onto the region 97A along the outer periphery of the defective device 15a. Similarly, when processing the wafer 11 by water jet processing, for example, the liquid 78 is sprayed onto the region 97A along the outer periphery of the defective device 15a. As a result, a groove 93 (see FIGS. 22(A) and 22(B)) or a through-hole 95 (see FIGS. 24(A) and 24(B)) is formed so as to surround the defective device 15a. The abrasive 74 and the liquid 78 may be sprayed so as to impinge on a portion of the defective device 15a, or may be sprayed only onto the street 13 so as not to impinge on the defective device 15a.

[0215] When processing the wafer 11 by drilling, for example, the drill bit 82 sequentially processes a plurality of regions 97B along the outer periphery of the defective device 15a. Note that each of the plurality of regions 97B is set so as to overlap a portion of the adjacent other region 97. As a result, a groove 93 (see FIG. 22(C)) or a through hole 95 (see FIG. 24(C)) is formed so as to surround the defective device 15a. Note that the drill bit 82 may contact a portion of the defective device 15a, or may contact only the street 13 so as not to contact the defective device 15a.

[0216] Furthermore, when processing the wafer 11 by drilling, the drill bit 82 may be rotated and moved horizontally along the street 13 while the drill bit 82 is inserted into the wafer 11 (see FIGS. 22(C) and 24(C)), thereby forming the grooves 93 or through-holes 95. In this case, the work of raising and lowering the drill bit 82 multiple times on the street 13 becomes unnecessary.

[0217] Thereafter, the inner walls of the through-holes 11d are etched by subjecting the wafer 11 to an etching process (such as plasma etching, see FIG. 26). As a result, minute irregularities remaining in the crushed regions 97A and 97B are removed, and the width of the through-holes 11d is increased, forming the enlarged through-holes 11d as shown in FIGS. 27(A) and 27(B).

[0218] As described above, in the removal step, the defective device region 11c can also be separated from the wafer 11 by crushing. Note that, among the steps included in the removal step, steps whose description is omitted in this embodiment are the same as those in embodiment 1. In addition, in this embodiment, steps other than the removal step (wafer preparation step, grinding step, embedding step, resin filling step, resin grinding step, wafer stacking step, division step, etc.) can be performed in the same way as in embodiment 1. Furthermore, this embodiment can be combined with other embodiments as appropriate.

[0219] (Embodiment 3) In the first and second embodiments, an example has been described in which the defective device region 11c is separated from the wafer 11 by processing the wafer 11 along the streets 13 in the removal step. However, there is no limitation on the method for removing the defective device region 11c from the wafer 11. In this embodiment, a method will be described in which the defective device region 11c is destroyed and removed by irradiating it with a laser beam in the removal step after the wafer preparation step and grinding step (see FIG. 2) are performed.

[0220] 28(A) is a cross-sectional view showing the wafer 11 to be irradiated with a laser beam 32D. When the defective device region 11c is destroyed by irradiating the laser beam, a laser irradiation unit 30D is used to irradiate the wafer 11 with the laser beam 32D. The configuration of the laser irradiation unit 30D is the same as that of the laser irradiation unit 30A (see FIG. 4(A)).

[0221] However, the irradiation conditions of the laser beam 32D are set so that the region of the wafer 11 irradiated with the laser beam 32D is removed by ablation. Specifically, the wavelength of the laser beam 32D is set so that at least a portion of the laser beam 32D is absorbed by the wafer 11. In other words, the laser irradiation unit 30D irradiates the laser beam 32D with a wavelength that is absorbed by the wafer 11. In addition, other irradiation conditions of the laser beam 32D are also set so that the wafer 11 is appropriately ablated.

[0222] For example, the laser beam 32D is irradiated onto the front surface 11a of the wafer 11. Specifically, the laser beam 32D is irradiated with the focal point of the laser beam 32D positioned inside the four streets 13 surrounding the defective device 15a. This causes ablation processing to be performed on the defective device region 11c, destroying the defective device region 11c. As a result, a groove (recess) is formed on the front surface 11a of the wafer 11.

[0223] 28(B) is a cross-sectional view showing the wafer 11 in which a groove (removal region) 101 is formed. For example, the laser beam 32D is scanned so as to irradiate the entire rectangular region in plan view located inside the four streets 13 surrounding the defective device 15a. As a result, a rectangular parallelepiped groove 101 is formed on the front surface 11a side of the wafer 11 by ablation processing. The depth of the groove 101 is adjusted so that the bottom surface of the groove 101 is formed below the lower end of the electrode 19. As a result, the defective device 15a and the electrode 19 are removed.

[0224] 29 is a plan view showing a path 34D scanned by the laser beam 32D. For example, a plurality of paths 34D are set from one end of the defective device region 11c to the other end. The laser beam 32D scans along the path 34D, traveling back and forth between one end and the other end of the defective device region 11c. This causes the laser beam 32D to irradiate the entire defective device region 11c, thereby removing the defective device region 11c. However, there are no limitations on the scanning path of the laser beam 32D as long as it is possible to remove the defective device region 11c.

[0225] When forming the groove 101, the front surface 11a side of the wafer 11 may be covered with a protective film, and the laser beam 32D may be irradiated onto the wafer 11 through the protective film. For example, the protective film may be a resin tape or a film made of a water-soluble resin such as PVA or PEG. If a protective film is formed on the front surface 11a side of the wafer 11, it is possible to prevent processing debris generated during the ablation process from adhering to the front surface 11a of the wafer 11, thereby avoiding contamination of the wafer 11 and the semiconductor device 15.

[0226] Next, the back surface 11b side of the wafer 11 is ground, thereby exposing the processing area (groove 101) processed by the irradiation of the laser beam 32D on the back surface 11b side of the wafer 11. When grinding the wafer 11, first, the wafer 11 is fixed to a support substrate. FIG. 30(A) is a cross-sectional view showing the wafer 11 fixed to the support substrate 23. When grinding the back surface 11b side of the wafer 11, the front surface 11a side of the wafer 11 is fixed to the support substrate 23 via an adhesive layer 25.

[0227] Next, the wafer 11 is ground by a grinding device 2 (see FIG. 2). Specifically, the back surface 11b of the wafer 11 is ground by bringing a grinding wheel 16 into contact with the back surface 11b of the wafer 11. Then, the wafer 11 is ground and thinned until the grooves 101 are exposed on the back surface 11b of the wafer 11.

[0228] 30(B) is a cross-sectional view showing the ground wafer 11. When the grooves 101 are exposed on the back surface 11b side of the wafer 11, through-holes 11d are formed in the wafer 11, extending from the front surface 11a to the back surface 11b.

[0229] In the removing step, the through-holes 11d may be formed directly by irradiation with the laser beam 32D. Specifically, the through-holes 11d are formed by ablation processing, from the front surface 11a to the back surface 11b of the wafer 11.

[0230] 31(A) is a cross-sectional view showing a wafer 11 to be irradiated with a laser beam 32D. First, a protective member 103 such as tape is attached to the wafer 11. For example, when the laser beam 32D is irradiated onto the front surface 11a of the wafer 11, the protective member 103 is attached to the back surface 11b of the wafer 11. An example of the material of the protective member 103 is the same as that of the protective member 21 (see FIG. 2).

[0231] Then, the laser beam 32D is irradiated with the focal point of the laser beam 32D positioned inside the four streets 13 surrounding the defective device 15a. There is no limitation on the scanning path of the laser beam 32D. For example, the laser beam 32D scans along a path 34D shown in FIG. 29.

[0232] The irradiation conditions of the laser beam 32D are set so that the region from the front surface 11a to the back surface 11b of the wafer 11 is removed by ablation. Therefore, when the irradiation of the laser beam 32D onto the wafer 11 is completed, a through-hole 11d is formed that penetrates the wafer 11 from the front surface 11a to the back surface 11b.

[0233] Thereafter, the wafer 11 is fixed to a support substrate. Fig. 31(B) is a cross-sectional view showing the wafer 11 fixed to the support substrate 23. After the through-holes 11d are formed in the wafer 11, the support substrate 23 is fixed to the front surface 11a side of the wafer 11 via an adhesive layer 25. Thereafter, the protective member 103 is peeled off from the front surface 11a side of the wafer 11.

[0234] The through-hole 11d can also be formed using a laser beam (aqua laser) irradiated through a liquid. In this case, an injection unit that injects a liquid is provided in the laser irradiation unit 30D. The liquid is then injected from the laser irradiation unit 30D to form a liquid column 50 (see FIG. 13(A)), and a laser beam 32D is irradiated from the laser irradiation unit 30D. At this time, the focal point of the laser beam 32D is positioned inside the liquid column 50. The laser beam 32D is then irradiated onto the defective device region 11c through the liquid column 50. This removes the defective device region 11c.

[0235] Furthermore, the wafer 11 in which the through-hole 11d is formed by the destruction of the defective device region 11c (see FIGS. 30(B) and 31(A)) may be subjected to an etching process. For example, plasma etching is performed on the inside of the through-hole 11d by supplying a plasma state gas to the through-hole 11d of the wafer 11. Alternatively, wet etching is performed on the inside of the through-hole 11d by supplying an etching solution to the through-hole 11d of the wafer 11.

[0236] As described above, in the removal step, the defective device region 11c can also be removed from the wafer 11 by destroying the defective device region 11c by irradiating it with a laser beam. Note that, among the steps included in the removal step, steps whose description is omitted in this embodiment are the same as those in embodiment 1. Also, in this embodiment, steps other than the removal step (such as the wafer preparation step, grinding step, embedding step, resin filling step, resin grinding step, wafer stacking step, and division step) can be performed in the same way as in embodiment 1. Furthermore, this embodiment can be combined with other embodiments as appropriate.

[0237] (Embodiment 4) In the third embodiment, an example in which the defective device region 11c is destroyed by irradiation with a laser beam in the removal step has been described, but there is no limitation on the method for destroying the defective device region 11c. In this embodiment, a method in which the defective device region 11c is destroyed and removed by a crushing process in the removal step after the wafer preparation step and the grinding step (see FIG. 2) have been performed will be described.

[0238] The crushing process used in this embodiment is not limited as long as it can process the wafer 11. Below, as specific examples of crushing processes, sandblasting using a sandblasting unit 72 (see FIG. 22(A) etc.), water jet machining using a water jet unit 76 (see FIG. 22(B) etc.), and drilling using a drill unit 80 (see FIG. 22(C) etc.) will be described.

[0239] 32 is a cross-sectional view showing the wafer 11 held by the holding table 70. When performing the crushing process, first, a protective layer 91 is formed on the wafer 11. For example, when processing is performed from the front surface 11a side of the wafer 11, the front surface 11a side of the wafer 11 is covered with the protective layer 91, and the semiconductor devices 15 are protected. Note that if the semiconductor devices 15 are unlikely to be damaged by the crushing process, the formation of the protective layer 91 may be omitted.

[0240] Next, the wafer 11 is held by the holding table 70. For example, the wafer 11 is placed on the holding table 70 so that the front surface 11a is exposed upward and the back surface 11b faces the holding surface 70a. Then, the wafer 11 held by the holding table 70 is subjected to a crushing process.

[0241] 33(A) is a cross-sectional view showing a wafer 11 from which a defective device region 11c has been removed by sandblasting. When sandblasting is performed, abrasive material 74 is sprayed from a sandblasting unit 72 onto the inside of four streets 13 surrounding a defective device 15a (see FIG. 32). As a result, the region of the wafer 11 hit by the abrasive material 74 is destroyed, and a rectangular parallelepiped groove (removal region) 105 is formed on the front surface 11a side of the wafer 11.

[0242] 33(B) is a cross-sectional view showing the wafer 11 from which the defective device region 11c has been removed by water jet processing. When water jet processing is performed, pressurized liquid 78 is sprayed from a water jet unit 76 onto the inside of the four streets 13 surrounding the defective device 15a (see FIG. 32). As a result, the region of the wafer 11 on which the liquid 78 collides is destroyed, and a rectangular parallelepiped groove 105 is formed on the front surface 11a side of the wafer 11.

[0243] The grooves 105 are formed over at least the entire region where the defective devices 15a are formed. The depth of the grooves 105 is adjusted so that the bottom surfaces of the grooves 105 are formed below the lower ends of the electrodes 19. As a result, the defective devices 15a and the electrodes 19 are removed.

[0244] FIG. 33(C) is a cross-sectional view showing the wafer 11 from which the defective device region 11c has been removed by drilling. When drilling, a rotating drill bit 82 is brought into contact with the inside of the four streets 13 surrounding the defective device 15a (see FIG. 32) to form multiple columnar grooves in the wafer 11. The multiple grooves are formed so that they are connected to each other throughout the entire region in which the defective device 15a is formed. The depth of the multiple grooves is adjusted so that the bottom surfaces of the grooves 105 are formed below the lower ends of the electrodes 19. As a result, grooves 105 formed by the multiple connected grooves are formed on the front surface 11a of the wafer 11, and the defective device 15a and the electrodes 19 are removed.

[0245] As described above, the defective device 15a is destroyed by performing the crushing process on the inside of the street 13 surrounding the defective device 15a, and the defective device 15a is thereby removed from the wafer 11.

[0246] Next, the back surface 11b side of the wafer 11 is ground to expose the processed region (groove 105) processed by the crushing process on the back surface 11b side of the wafer 11. When grinding the wafer 11, first, the wafer 11 is fixed to the support substrate 23. FIG. 34(A) is a cross-sectional view showing the wafer 11 fixed to the support substrate 23. When grinding the back surface 11b side of the wafer 11, the front surface 11a side of the wafer 11 is fixed to the support substrate 23 via an adhesive layer 25.

[0247] Next, the wafer 11 is ground by a grinding device 2 (see FIG. 2). Specifically, the back surface 11b of the wafer 11 is ground by bringing a grinding wheel 16 into contact with the back surface 11b of the wafer 11. Then, the wafer 11 is ground and thinned until the grooves 105 are exposed on the back surface 11b of the wafer 11.

[0248] 34(B) is a cross-sectional view showing the ground wafer 11. When the grooves 105 are exposed on the back surface 11b side of the wafer 11, rectangular parallelepiped through-holes 11d are formed in the wafer 11, extending from the front surface 11a to the back surface 11b.

[0249] In the removing step, the through-holes 11d may be formed directly by crushing. Specifically, the through-holes 11d that reach the back surface 11b of the wafer 11 from the front surface 11a are formed by crushing.

[0250] 35(A) is a cross-sectional view showing a wafer 11 in which through-holes 11d are formed by sandblasting. When the through-holes 11d are formed in the wafer 11 by crushing, openings 70c are provided in the holding table 70, penetrating the holding table 70 from top to bottom. The wafer 11 is then placed on the holding table 70 so that the inner regions of the four streets 13 surrounding the defective device 15a overlap with the openings 70c.

[0251] Next, abrasive material 74 is sprayed from sandblasting unit 72 onto the entire area inside four streets 13 surrounding defective device 15a (see FIG. 32). The spraying conditions for abrasive material 74 are set so that the area of ​​wafer 11 that is hit by abrasive material 74 is removed from front surface 11a to back surface 11b. As a result, defective device area 11c is removed and through-holes 11d are formed in wafer 11.

[0252] 35(B) is a cross-sectional view showing a wafer 11 in which a through-hole 11d is formed by water jet processing. When water jet processing is performed, a liquid 78 is sprayed from a water jet unit 76 over the entire area inside the four streets 13 surrounding a defective device 15a (see FIG. 32). The spraying conditions for the liquid 78 are set so that the area of ​​the wafer 11 on which the liquid 78 collides is removed from the front surface 11a to the back surface 11b. As a result, the defective device area 11c is removed and a through-hole 11d is formed in the wafer 11.

[0253] 35(C) is a cross-sectional view showing the wafer 11 in which through-holes 11d are formed by drilling. When performing drilling, a rotating drill bit 82 is brought into contact with the insides of the four streets 13 surrounding the defective device 15a (see FIG. 32) to form multiple columnar grooves in the wafer 11.

[0254] The drill bit 82 processes the wafer 11 until the lower end of the drill bit 82 reaches the back surface 11b of the wafer 11. As a result, a plurality of grooves are formed so as to penetrate the wafer 11 from the front surface 11a to the back surface 11b. The plurality of grooves are also formed so as to be connected to one another over at least the entire region where the defective devices 15a are formed. As a result, a through hole 11d is formed, which is made up of the plurality of connected grooves.

[0255] During sandblasting (see FIG. 35(A)), abrasive 74 that passes through through-hole 11d of wafer 11 is discharged via opening 70c of holding table 70. Similarly, during water jet processing (see FIG. 35(B)), liquid 78 that passes through through-hole 11d of wafer 11 is discharged via opening 70c of holding table 70. This prevents abrasive 74 and liquid 78 from colliding with holding surface 70a of holding table 70 and damaging holding table 70.

[0256] Furthermore, when sandblasting (see FIG. 35(C)) is performed, the tip of the drill bit 82 is inserted into the opening 70c of the holding table 70. This prevents the drill bit 82 from coming into contact with the holding table 70 and damaging the holding table 70.

[0257] 35(A), 35(B), and 35(C) show the wafer 11 being processed from the front surface 11a side, but the wafer 11 may also be processed from the back surface 11b side. That is, the abrasive 74 or liquid 78 may be collided with the back surface 11b side of the wafer 11, or the drill bit 82 may be brought into contact with the back surface 11b side of the wafer 11.

[0258] Thereafter, the wafer 11, in which the defective device region 11c has been removed and the through-holes 11d have been formed, is fixed to the support substrate 23. Fig. 36 is a cross-sectional view showing the wafer 11 fixed to the support substrate 23. For example, the front surface 11a side of the wafer 11 is fixed to the support substrate 23 via an adhesive layer 25.

[0259] The wafer 11 in which the through-holes 11d are formed by the crushing process may be subjected to an etching process. For example, plasma etching is performed on the inside of the through-holes 11d by supplying a plasma gas to the through-holes 11d of the wafer 11 (see FIG. 26). Alternatively, wet etching is performed on the inside of the through-holes 11d by supplying an etching solution to the through-holes 11d of the wafer 11. By performing the etching process on the wafer 11, the size of the through-holes 11d increases and minute irregularities formed on the inner walls of the through-holes 11d by the crushing process are removed.

[0260] The area of ​​the wafer 11 to be subjected to the crushing process is appropriately set so that through-holes 11d are formed inside at least four streets 13 surrounding the defective device 15a (see FIG. 32). FIG. 37(A) is a plan view showing an area (processed area) 97C to be processed by sandblasting or water jet processing. FIG. 37(B) is a plan view showing an area (processed area) 97D to be processed by drilling. In FIGS. 37(A) and 37(B), patterns are applied to areas 97C and 97D.

[0261] When processing the wafer 11 by sandblasting, the abrasive 74 is sprayed onto the region 97C that includes the entire defective device 15a. Similarly, when processing the wafer 11 by water jet processing, for example, the liquid 78 is sprayed onto the region 97C that includes the entire defective device 15a. This forms a groove 105 (see FIGS. 33(A) and 33(B)) or a through-hole 11d (see FIGS. 35(A) and 35(B)) so that the defective device 15a is removed. The abrasive 74 and the liquid 78 may be sprayed so as to impinge on a portion of the street 13 that surrounds the defective device 15a.

[0262] When processing the wafer 11 by drilling, a drill bit 82 sequentially processes a plurality of regions 97D overlapping with the defective devices 15a. Each of the plurality of regions 97D is set so as to overlap a portion of an adjacent region 97D. This forms a groove 105 (see FIG. 33(C)) or a through-hole 11d (see FIG. 35(C)) so as to remove the defective devices 15a. The drill bit 82 may contact a portion of the street 13 surrounding the defective devices 15a.

[0263] Furthermore, when processing the wafer 11 by drilling, the grooves 105 or through-holes 11d may be formed by rotating and moving the drill bit 82 horizontally while the drill bit 82 is inserted into the wafer 11 (see FIGS. 33(C) and 35(C)). In this case, there is no need to raise and lower the drill bit 82 multiple times.

[0264] Thereafter, the wafer 11 is subjected to an etching process (such as plasma etching, see FIG. 26) to etch the inner walls of the through-holes 11d, which results in removing minute irregularities remaining in the crushed regions 97C and 97D, and increasing the width of the through-holes 11d, thereby forming the enlarged through-holes 11d shown in FIGS. 37(A) and 37(B).

[0265] As described above, in the removal step, the defective device region 11c can also be removed from the wafer 11 by destroying the defective device region 11c by crushing. Note that, among the steps included in the removal step, steps whose description is omitted in this embodiment are the same as those in embodiment 1. Also, in this embodiment, steps other than the removal step (such as the wafer preparation step, grinding step, embedding step, resin filling step, resin grinding step, wafer stacking step, and division step) can be performed in the same way as in embodiment 1. Furthermore, this embodiment can be combined with other embodiments as appropriate.

[0266] (Embodiment 5) In this embodiment, a description will be given of the relationship between a step of removing the defective device region 11c from the wafer 11 (removal step) and a step of fixing the wafer 11 to the support substrate 23 (support substrate fixing step). Specifically, in this embodiment, a process of fixing the wafer 11 to the support substrate 23 after the defective device region 11c is removed from the wafer 11 will be described in detail.

[0267] First, the wafer 11 prepared in the preparation step is subjected to grinding (see FIG. 2) as needed (grinding step). Then, the wafer 11 is subjected to processing such as laser processing or crushing to remove the defective device region 11c from the wafer 11 (removing step). Thereafter, the wafer 11 from which the defective device region 11c has been removed and in which the through-hole 11d has been formed is fixed to a support substrate 23 (support substrate fixing step).

[0268] The defective device region 11c can be removed by laser processing. For example, the defective device region 11c is separated from the wafer 11 by laser processing (see FIGS. 12(A), 13(A), etc.), and then the wafer 11 is fixed to the support substrate 23 (see FIGS. 12(B), 13(B), etc.). Alternatively, the defective device region 11c is destroyed by laser processing (see FIG. 31(A), etc.), and then the wafer 11 is fixed to the support substrate 23 (see FIG. 31(B), etc.).

[0269] Furthermore, the defective device region 11c can also be removed by a crushing process. For example, the defective device region 11c is separated from the wafer 11 by a crushing process (see FIGS. 24(A), 24(B), 24(C), etc.), and then the wafer 11 is fixed to the support substrate 23 (see FIG. 25, etc.). For example, the defective device region 11c is destroyed by a crushing process (see FIGS. 35(A), 35(B), 35(C), etc.), and then the wafer 11 is fixed to the support substrate 23 (see FIG. 36, etc.).

[0270] Then, device chips 59 are fitted into the through holes 11d of the wafer 11 fixed to the support substrate 23 (fitting step, see FIGS. 16 to 18C, etc.), thereby manufacturing a wafer 11 that does not include defective devices 15a.

[0271] As described above, when the support substrate fixing step is performed after the removal step, the defective device region 11c has already been removed from the wafer 11 when the wafer 11 is fixed to the support substrate 23. Therefore, it is not necessary to perform processing to remove the defective device region 11c after the wafer 11 is fixed to the support substrate 23. This makes it possible to prevent debris (processing debris) generated by processing the wafer 11 from adhering to the support substrate 23, and to prevent processing debris adhering to the support substrate 23 from interfering with the fitting of the device chips 59 into the through holes 11d.

[0272] There is no limitation on the method for fixing the wafer 11 to the support substrate 23. For example, the wafer 11 is fixed to the wafer 11 via an adhesive layer 25. As described above, the adhesive layer 25 can be, for example, an adhesive made of a thermosetting resin, an adhesive made of a thermoplastic resin, an adhesive made of an ultraviolet curable resin, a sheet that can be fixed to the wafer 11 and the support substrate 23 by heating and pressurizing and does not contain an adhesive (thermocompression sheet), a tape with a thermal foam layer, or the like.

[0273] Thereafter, a resin filling step (see FIG. 19(A)), a resin grinding step (see FIG. 19(B)), a wafer stacking step (see FIG. 20), and a dividing step (see FIG. 21(A)) are carried out in this order, thereby manufacturing a stacked device chip 81 including a plurality of stacked semiconductor devices (see FIG. 21(B)).

[0274] As described above, by performing the support substrate fixing step after performing the removal step, adhesion of processing debris to the support substrate 23 can be prevented, and the operation of fitting the device chip 59 into the wafer 11 can be performed smoothly. Note that, among the steps included in the removal step and the support substrate fixing step, steps that are not described in this embodiment are the same as those in embodiment 1. Also, in this embodiment, steps other than the removal step and the support substrate fixing step (wafer preparation step, grinding step, fitting step, resin filling step, resin grinding step, wafer stacking step, division step, etc.) can be performed in the same way as in embodiment 1. Furthermore, this embodiment can be combined with other embodiments as appropriate.

[0275] (Embodiment 6) In this embodiment, a description will be given of the relationship between a step of removing the defective device region 11c from the wafer 11 (removal step) and a step of fixing the wafer 11 to the support substrate 23 (support substrate fixing step). Specifically, in this embodiment, a process of removing the defective device region 11c from the wafer 11 after the wafer 11 is fixed to the support substrate 23 will be described in detail.

[0276] First, the wafer 11 prepared in the preparation step is subjected to grinding (see FIG. 2) as needed (grinding step). Then, the wafer 11 is fixed to a support substrate 23 (support substrate fixing step). After that, the wafer 11 is subjected to processing such as laser processing and crushing, thereby removing the defective device region 11c from the wafer 11 (removal step).

[0277] The defective device region 11c can be removed by laser processing. For example, the wafer 11 fixed to the support substrate 23 is subjected to laser processing (see FIG. 4(A) and the like), and then the defective device region 11c is separated from the wafer 11 (see FIG. 8(B) and the like). Alternatively, the wafer 11 fixed to the support substrate 23 is subjected to plasma etching (see FIG. 14(B) and the like), and then the defective device region 11c is removed from the wafer 11 (see FIG. 8(B) and the like).

[0278] Furthermore, for example, the wafer 11 having grooves formed therein by laser processing, crushing processing, or the like is fixed to the support substrate 23 (see FIGS. 11(A), 23(A), etc.). Thereafter, the wafer 11 is ground (see FIGS. 11(B), 23(B), etc.) to remove the defective device region 11c from the wafer 11.

[0279] There is no limitation on the method for fixing the wafer 11 to the support substrate 23. For example, the wafer 11 is fixed to the wafer 11 via an adhesive layer 25. As described above, the adhesive layer 25 can be, for example, an adhesive made of a thermosetting resin, an adhesive made of a thermoplastic resin, an adhesive made of an ultraviolet curable resin, a sheet that can be fixed to the wafer 11 and the support substrate 23 by heating and pressurizing and does not contain an adhesive (thermocompression sheet), a tape with a thermal foam layer, or the like.

[0280] Then, device chips 59 are fitted into the through holes 11d of the wafer 11 fixed to the support substrate 23 (fitting step, see FIGS. 16 to 18C), thereby manufacturing a wafer 11 that does not include any defective devices 15a.

[0281] As described above, when the removing step is performed after the support substrate fixing step, the wafer 11 is supported by the support substrate 23 at the stage when the defective device region 11c is removed from the wafer 11. Therefore, the embedding step can be performed thereafter in succession, and the device chip 59 can be smoothly embedded.

[0282] Furthermore, when the removing step is performed after the support substrate fixing step, the grinding process (see FIGS. 11(B), 23(B), etc.) for separating the defective device region 11c from the wafer 11 is performed after the operation of fixing the wafer 11 to the support substrate 23. This eliminates the need for the operation of transporting the wafer 11, which is thinned and easily deformed, and bonding it to the support substrate 23, thereby improving work efficiency and preventing damage to the wafer.

[0283] Thereafter, a resin filling step (see FIG. 19(A)), a resin grinding step (see FIG. 19(B)), a wafer stacking step (see FIG. 20), and a dividing step (see FIG. 21(A)) are carried out in this order, thereby manufacturing a stacked device chip 81 including a plurality of stacked semiconductor devices (see FIG. 21(B)).

[0284] As described above, by performing the removal step after the support substrate fixing step, a smooth transition to the subsequent embedding step can be achieved. Note that, among the steps included in the support substrate fixing step and the removal step, steps whose description is omitted in this embodiment are the same as those in embodiment 1. Furthermore, in this embodiment, steps other than the support substrate fixing step and the removal step (wafer preparation step, grinding step, embedding step, resin filling step, resin grinding step, wafer stacking step, division step, etc.) can be performed in the same way as in embodiment 1. Furthermore, this embodiment can be combined with other embodiments as appropriate.

[0285] The structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0286] 11 wafers 11a Surface (first side) 11b Back side (2nd side) 11c Bad Device Area 11d Through hole (removal area) 13th Street (Planned division line) 15 Semiconductor Devices 15a Bad Device 17 electrodes 19 Electrodes (via electrodes, through electrodes) 21 Protective material 23 Support board 25 Adhesive layer 27 Modified layer (altered layer) 27a Modified area (altered area) 29 Crack 31 Groove 33 Protective materials 35 Calf (cut) 37 Mask Layer 39 Mask 51 wafers 51a Surface (first side) 51b Back side (2nd side) 53rd Street (Planned division line) 55 Semiconductor Devices 57 Electrodes (via electrodes, through electrodes) 59 Device Chips 61 Gap 63 Adhesive layer 65 Resin 71 wafers 71a Front (first side) 71b Back side (2nd side) 73rd Street (Planned division line) 75 Semiconductor Devices 77 Electrodes (via electrodes, through electrodes) 79 stacked wafers 81 Stacked Device Chip 91 Protective layer 93 Groove 95 through holes 97A, 97B, 97C, 97D area (processed area) 101 Groove (removal area) 103 Protective materials 105 groove (removal area) 2 Grinding equipment 4 Chuck table 4a Holding surface 6 Grinding Unit 8 spindles 10 Mount 12 Grinding wheels 14 Foundation 16 Grinding Wheel 18 nozzles 20 Grinding fluid 30A, 30B, 30C, 30D Laser irradiation unit 32A, 32B, 32C, 32D Laser beam Routes 34A, 34B, 34C, and 34D 36 Gas (etching gas) 38 Mask 38a aperture 40 Energy Imparting Units 42 Ultrasonic irradiation unit 44 Container 46 Liquid 48 Ultrasonic Transmitter 50 liquid column 52 Holding table 52a Holding surface 52b aperture 54 Laser irradiation unit 56 Laser Beam 58 Gas (etching gas) 60 Gas (etching gas) 62 Cutting blade 70 Holding Table 70a holding surface 70b,70c opening 72 Sandblasting Unit 74 Abrasives 76 Water Jet Unit 78 Liquid 80 Drill Unit 82 Drill Bit 84 Gas (etching gas)

Claims

1. A wafer preparation step of preparing a wafer having semiconductor devices formed in a plurality of areas partitioned by a plurality of intersecting streets; a removing step of separating from the wafer a defective device region including a semiconductor device determined to be defective among the plurality of semiconductor devices formed on the wafer; a fitting step of fitting a device chip, which is a non-defective semiconductor device having the same function as the semiconductor device determined to be defective and has a size capable of being fitted into a through hole formed by separating the defective device region from the wafer, into the through hole; In the removing step, a laser beam is irradiated along the street surrounding the semiconductor device determined to be defective; A method for manufacturing a wafer, characterized in that in the removal step, a second surface side of the wafer opposite to a first surface side on which the semiconductor device is formed is ground to expose a processed area processed by irradiation with the laser beam or a crack propagating from the processed area on the second surface side of the wafer.

2. 2. The method for manufacturing a wafer according to claim 1, wherein in the removing step, a laser beam having a wavelength that is transparent to the wafer is irradiated along the street with a focal point of the laser beam positioned inside the wafer, thereby forming a modified layer along the street that functions as a starting point for separating the defective device region.

3. 2. The method for manufacturing a wafer according to claim 1, wherein the removing step removes a region of the wafer along the street by irradiating the laser beam along the street with a focal point of the laser beam having a wavelength absorbent for the wafer positioned at the street.

4. 2. The method for manufacturing a wafer according to claim 1, wherein in the removing step, a focal point of the laser beam having a wavelength absorbent for the wafer is positioned inside a liquid column formed by spraying a liquid toward the wafer, and the laser beam is irradiated along the street through the liquid column, thereby removing the area of ​​the wafer along the street.

5. 5. The method for manufacturing a wafer according to claim 1, further comprising a grinding step of attaching a protective member to a first surface side of the wafer on which the semiconductor devices are formed, and grinding a second surface side of the wafer opposite to the first surface, to thin the wafer to a predetermined thickness, before carrying out the removing step.

6. 6. The method for manufacturing a wafer according to claim 1, wherein in the removing step, an etching solution is supplied to the processed area processed by the irradiation of the laser beam or to a crack propagating from the processed area.

7. A method for manufacturing a wafer according to any one of claims 1 to 5, characterized in that in the removal step, a plasmatized gas is supplied to the processed area processed by irradiation of the laser beam or to a crack propagating from the processed area.

8. a resin filling step of filling a gap between the device chip and the wafer with resin after the embedding step is performed; 8. The method for manufacturing a wafer according to claim 1, further comprising a resin grinding step of grinding the resin formed outside the gap after the resin filling step is performed.

9. a wafer preparation step of preparing a first wafer and a second wafer, each of which has semiconductor devices formed in a plurality of regions defined by a plurality of intersecting streets; a removing step of separating from the first wafer a defective device region including a semiconductor device determined to be defective among the plurality of semiconductor devices formed on the first wafer; a fitting step of fitting a device chip, which includes a non-defective semiconductor device having the same function as the semiconductor device determined to be defective and has a size that allows it to be fitted into a through hole formed by separating the defective device region from the first wafer, into the through hole; a wafer stacking step of stacking the second wafer on the first wafer to form a stacked wafer; A dividing step of dividing the stacked wafer along the streets to form stacked device chips including a plurality of the semiconductor devices stacked together; In the removing step, a laser beam is irradiated along the street surrounding the semiconductor device determined to be defective; The method for manufacturing a stacked device chip is characterized in that in the removal step, a second surface side of the first wafer opposite to the first surface side on which the semiconductor device is formed is ground to expose a processed area processed by irradiation with the laser beam or a crack propagating from the processed area on the second surface side of the first wafer.

Images