Processing method of wafer and manufacturing method of device chip

Abstract

To enable prevention of adhesion of debris.SOLUTION: A processing method of a wafer is a processing method of a wafer for cutting a boundary between a convex part and a concave part of a wafer having a protective member fixed to a first surface on which the concave part and the ring-shaped convex part surrounding the concave part are formed, and includes: a holding step S1 of holding the protective member side on a holding table; a protective film forming step S2 of forming a protective film in a region including the boundary of the wafer held on the holding table; an inspection step S3 of inspecting the protective film formed on the wafer; and a cutting step S7 of cutting the wafer along the boundary by applying a laser beam to the boundary after the inspection step S3 when the wafer has passed the inspection in the inspection step S3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wafer processing method and a device chip manufacturing method. [Background technology]

[0002] In recent years, wafers have been proposed that ensure rigidity by forming a reinforcing annular convex portion in the peripheral excess region surrounding the device region. In such wafers, the annular convex portion is removed by a laser ablation process during the chip manufacturing process, but this process poses a problem in that debris generated by the ablation process adheres to the wafer surface.

[0003] Techniques related to such problems are described, for example, in Patent Documents 1 and 2. Patent Documents 1 and 2 describe coating the area of ​​the wafer to be irradiated with the laser beam with a protective film in advance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-114113 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-322168 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the protective film is not formed appropriately, there is a risk that debris will adhere to the wafer surface. The present invention has been made in view of this problem, and provides a wafer processing method and a device chip manufacturing method that can prevent debris from adhering. [Means for solving the problem]

[0006] A wafer processing method according to one aspect of the present invention is a wafer processing method for cutting the boundary between a recess and a ring-shaped protrusion surrounding the recess of a wafer having a protective member fixed to a first surface on which the recess and the protrusion are formed, the method comprising: a holding step for holding the protective member side on a holding table; a protective film forming step for forming a protective film in an area of ​​the wafer held on the holding table that includes the boundary; an inspection step for inspecting the protective film formed on the wafer; and a cutting step for irradiating a laser beam onto the boundary after the inspection step to cut the wafer along the boundary if the wafer passes inspection in the inspection step.

[0007] A device chip manufacturing method according to one aspect of the present invention is a device chip manufacturing method for manufacturing a plurality of device chips, and includes: a holding step for holding the protective member side of a wafer, the protective member being fixed to a first surface on which a recess and a ring-shaped protrusion surrounding the recess are formed, on a holding table; a protective film forming step for forming a protective film in an area including the boundary of the wafer held on the holding table; an inspection step for inspecting the protective film formed on the wafer; if the wafer passes inspection in the inspection step, a cutting step for irradiating a laser beam onto the boundary after the inspection step to cut the wafer along the boundary; and a dividing step for dividing the area corresponding to the recess to manufacture a plurality of device chips after the cutting step. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a wafer processing method and a device chip manufacturing method that can prevent adhesion of debris. [Brief explanation of the drawings]

[0009] [Figure 1] 3 is a flowchart showing a method for manufacturing the device chip according to the first embodiment. [Figure 2] FIG. 2 is a perspective view showing an example of a wafer surface. [Figure 3] FIG. 2 is a perspective view showing an example of the back surface of the wafer. [Figure 4]10A and 10B are diagrams illustrating a holding step and a protective film forming step. [Figure 5] FIG. 10 is a perspective view of the frame unit after a protective film is formed. [Figure 6] FIG. [Figure 7] FIG. 10 is a diagram illustrating an example of an image captured in an inspection step. [Figure 8] FIG. 2 shows a drying step. [Figure 9] FIG. [Figure 10] FIG. 10 illustrates a ring removal step. [Figure 11] FIG. 1 illustrates a division step. [Figure 12] 10 is a flowchart showing a method for manufacturing a device chip according to a second embodiment. [Figure 13] 10 is a flowchart showing a method for manufacturing a device chip according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (First embodiment) Fig. 1 is a flowchart showing a method for manufacturing a device chip according to this embodiment. The method for manufacturing a device chip according to this embodiment shown in Fig. 1 is a method for manufacturing device chips by dividing a wafer processed using the wafer processing method according to this embodiment. Steps S1 to S7 of the method for manufacturing a device chip according to this embodiment constitute the wafer processing method according to this embodiment.

[0011] The wafer used in this embodiment is a wafer produced by TAIKO (registered trademark) grinding. TAIKO grinding is a grinding process that forms a ring-shaped convex portion by thinning the wafer while leaving the peripheral region. With TAIKO grinding, the thinned wafer is reinforced by the ring-shaped convex portion, making it possible to suppress wafer deformation compared to when no convex portion is formed. Hereinafter, the ring-shaped convex portion formed in the peripheral region of the wafer will be referred to as a ring-shaped reinforcing portion.

[0012] 2 is a perspective view showing an example of the front surface 11 of the wafer 10. The front surface 11 of the wafer 10 has a device region 12 in which a plurality of devices 14 are formed. This device region 12 is partitioned by a plurality of planned division lines 15. In addition, a peripheral surplus region 13 in which no devices 14 are formed is provided on the outer periphery of the device region 12. In other words, the front surface 11 of the wafer 10 includes the device region 12 and the peripheral surplus region 13 surrounding the device region 12.

[0013] 3 is a perspective view showing an example of the back surface 16 of the wafer 10. In TAIKO grinding, the central region of the back surface 16 of the wafer 10 is ground and thinned, so that a recess 17 is formed on the back surface 16 of the wafer 10, as shown in FIG. 3. In addition, as the recess 17 is formed, a ring-shaped reinforcing portion 18 is formed on the outer periphery of the recess 17, maintaining the thickness before grinding. The ring-shaped reinforcing portion 18 is formed in a region of the back surface 16 corresponding to the outer periphery excess region 13 of the front surface 11.

[0014] The following describes the device chip manufacturing method shown in Fig. 1 and the wafer processing method performed in the device chip manufacturing method. The device chip manufacturing method may be performed in a single apparatus equipped with multiple units that perform each step, or may be performed by sharing the steps among multiple apparatuses.

[0015] Fig. 4 is a diagram showing the holding step and the protective film forming step. Fig. 5 is a perspective view of the frame unit U after the protective film has been formed. When the manufacturing process of the device chip using the manufacturing method of the device chip shown in Fig. 1 is started, first, the holding step and the protective film forming step are performed (steps S1 and S2).

[0016] 4, in the holding step of step S1, in preparation for a protective film forming step of step S2 in which a protective film is formed on the front surface 11 of the wafer 10, the back surface 16 side opposite the front surface 11 on which the protective film is to be formed is held on a holding table 50. The holding table 50 has a holding part 51 that is rotatable about a support shaft 52, and in the holding step, the wafer 10 is held by suction on the underside of the holding part 51.

[0017] In the holding step, the wafer 10 is carried in as part of a frame unit U. More specifically, the wafer 10 is carried in with a tape 30, which is a protective member, fixed to the back surface 16 of the wafer 10 held by a holding table 50. As shown in FIG. 5, the frame unit U is formed by attaching the wafer 10, which is the workpiece, to the tape 30 that covers the opening of an annular frame 20, thereby integrating the frame 20 and the wafer 10. Note that the protective film 40 shown in FIG. 5 is formed in a protective film forming step, which will be described later, and in the holding step, a frame unit U without the protective film 40 formed thereon is carried in.

[0018] In the protective film forming step of step S2, a protective film is formed on the wafer 10 held on the holding table 50 by a coating device 60 shown in Fig. 4. The protective film formed in the protective film forming step prevents debris generated in the cutting step (step S7) described later from adhering to the wafer 10.

[0019] Therefore, in the protective film forming step, it is desirable to form a protective film in an area of ​​the wafer 10 where debris is likely to be generated and adhere. Specifically, since the boundary between the recessed portion 17 and the ring-shaped reinforcing portion 18, which is a protruding portion, is cut with a laser in the cutting step, the protective film may be formed in an area including that boundary in the protective film forming step. In other words, the boundary can be rephrased as the portion to be irradiated with the laser beam in the cutting step (the line to cut 19), and the area including the boundary can be rephrased as the area including the line to cut 19.

[0020] Therefore, in the protective film forming step, a protective film is formed in an area including the cutting line 19 of the wafer 10 held on the holding table 50. Fig. 4 shows how a protective film is formed on the wafer 10 held on the holding table 50 by a coating device 60 in an area including the cutting line 19. Hereinafter, the area including the cutting line 19, which is the target for forming the protective film, will be referred to as a target area.

[0021] The coating device 60 is configured so that a liquid resin is delivered to the nozzle 61 via a liquid supply pipe 64 by a pump (not shown). The liquid resin is, for example, a water-soluble liquid resin such as PVA (polyvinyl alcohol). As shown in FIG. 4, the opening 63 at the tip 62 of the nozzle 61 is a long, thin slit. The coating device 60 is provided with an immersion device 70 in which the tip 62 of the nozzle 61 is immersed to prevent the tip 62 from drying out. The immersion device 70 has a bottom plate 71 having an opening 72 through which the nozzle 61 is inserted and a side wall 73 extending upward from the periphery of the bottom plate 71. The nozzle 61 is fixed within the immersion device 70 via a bracket (not shown). A bellows-shaped rubber cover 74 is attached to the bottom plate 71 and extends upward at an inward angle from the periphery of the opening 72 to prevent water 75 in the immersion device 70 from leaking out of the opening 72. The coating device 60 is further provided with an elevator device 80 that raises and lowers the nozzle 61. The elevator device 80 includes an actuator 82 that raises and lowers a connecting piece 81 connected to the nozzle 61, and when the actuator 82 is driven, the tip 62 of the nozzle 61 emerges from the surface of the water 75 in the immersion unit 70 and is positioned near the surface 11 of the wafer 10 held on the holding table 50. The position of the wafer 10 held on the holding table 50 is adjusted in advance so that the cutting line 19 is located on an extension of the nozzle 61.

[0022] The coating device 60 configured as described above forms a film of liquid resin, i.e., a protective film, in the area of ​​the surface 11 including the line to cut 19 by discharging liquid resin while the nozzle 61 is positioned near the line to cut 19 on the surface 11 of the wafer 10 as shown in Fig. 4. At this time, the holding table 50 rotates the holding part 51 around the support shaft 52, so that the coating device 60 can form the protective film in the area including the entire ring-shaped line to cut 19 that exists along the circumferential direction of the wafer 10. Fig. 5 shows the state in which the ring-shaped protective film 40 has been formed on the surface 11 of the wafer 10 in the frame unit U.

[0023] Fig. 6 is a diagram showing the inspection step. Fig. 7 is a diagram showing an example of an image taken in the inspection step. After the protective film forming step of step S2 is completed, an inspection step is performed to inspect the protective film 40 formed on the wafer 10 (step S3).

[0024] In the inspection step, as shown in FIG. 6, an image of the front surface 11 of the wafer 10 is acquired by an imaging unit 90 arranged on the front surface 11 side of the wafer 10, and the protective film 40 is inspected based on the acquired image. Specifically, for example, it is inspected whether the protective film 40 is formed in an area (target area) required to prevent debris adhesion. The target area is determined based on the cutting line 19 (boundary) to which the laser beam is irradiated, and is desirably defined in a form that can be identified on the image acquired in the inspection step, such as an area from a certain number of mm to a certain number of mm radially inward from the edge of the wafer 10 (front surface 11). In the following, an example will be described in which the range from 0 mm (i.e., the edge itself) to D mm radially inward from the edge is defined as the target area.

[0025] On the image acquired by the imaging unit 90, there is a large difference in brightness between the area where the protective film 40 is formed and other areas (areas on the wafer 10 where the protective film 40 is not formed and areas outside the wafer 10). For this reason, in the inspection step, it is possible to inspect whether or not the protective film 40 is formed in the target area by detecting the edge of the protective film 40 by connecting points where there is a large difference in brightness in the image.

[0026] For example, if a protective film formation step has been performed in advance so that at least the protective film 40 is formed near the edge of the front surface 11 of the wafer 10, the edge of the protective film 40 located radially outward of the wafer 10 among the edges of the protective film 40 detected in the image can be considered to be the edge of the front surface 11. Therefore, whether or not the protective film 40 is formed in the target area may be inspected by comparing the radial distance between the edges of the protective film 40 with the width of the target area (D mm in this example). In this case, for example, as shown in image 101 of FIG. 7(a), if the distance between the outer edge 411 and the inner edge 412 of the protective film 41 reaches the width D of the target area, it is determined that the protective film 41 is formed in the target area. Furthermore, as shown in image 102 of FIG. 7(b), if the distance between the outer edge 421 and the inner edge 422 of the protective film 42 is smaller than the width D of the target area, it is determined that the protective film 42 is not sufficiently formed in the target area. Furthermore, as shown in image 103 of Figure 7(c), even if the distance between the outer edge 431 and the inner edge 432 of the protective film 43 reaches the width D of the target area, if the protective film 43 is interrupted in the circumferential direction of the wafer 10, it is determined that the protective film 43 is not sufficiently formed in the target area.

[0027] If the protective film 40 is not necessarily formed near the edge of the front surface 11 of the wafer 10 in the protective film forming step, the edge of the front surface 11 of the wafer 10 may be detected in addition to the edge of the protective film 40 from the image, and whether or not the protective film 40 is formed in the target area may be inspected based on the detected edge of the protective film 40 and the edge of the front surface 11. The edge of the front surface 11 of the wafer 10 is not particularly limited, and may be detected based on the difference in brightness between on and off the wafer 10.

[0028] In the inspection step, it is desirable to rotate the wafer 10 on the holding table 50 while capturing images of different circumferential ranges of the wafer 10 with the imaging unit 90 to obtain multiple images, and then perform the above-mentioned inspection on each of the multiple images obtained.

[0029] In the above-described inspection, if defects such as the protective film not being formed with sufficient width, the protective film being interrupted in the circumferential direction, or the protective film being partially uncoated are found, and as a result the inspection is not passed (step S4 NO), a cleaning step (step S5) is performed to wash away the protective film formed on surface 11, and then the above-described processing is repeated again from the protective film forming step. Note that the cleaning step may be omitted, and if the inspection is not passed, a new protective film may be formed on top of the protective film that has already been partially formed in the protective film forming step.

[0030] 8 is a diagram showing the drying step. If the wafer passes the inspection (YES in step S4), the drying step is performed to dry the protective film 40 formed on the wafer 10 (step S6).

[0031] In the drying step, as shown in FIG. 8, while the wafer 10 is rotated on the holding table 50, an air supply unit 110 arranged on the surface 11 side of the wafer 10 supplies a gas such as air to the protective film 40 formed on the surface 11 of the wafer 10 to dry the protective film 40.

[0032] The air supply unit 110 is configured to supply gas from the radially outer side toward the inner side of the wafer 10. This is to prevent the fluid protective film 40 from moving radially outward across the front surface 11 before drying and from wrapping around the side of the wafer 10 beyond the edge of the front surface 11 of the wafer 10 during the drying step. This prevents problems that may occur, particularly in the ring removal step described below, due to the protective film 40 wrapping around the side of the wafer 10. Furthermore, debris adhesion should be prevented preferentially on the recess 17 side (radially inner side) that will become the final product rather than on the ring-shaped reinforcement portion 18 side (radially outer side). From this perspective, it is desirable to supply gas from the outer side toward the inner side. However, as long as the protective film 40 does not wrap around the side of the wafer 10, the air supply unit 110 may supply gas in any direction to dry the protective film 40.

[0033] 9 is a diagram showing the cutting step. After the drying step is completed, the cutting step of cutting the wafer 10 is performed (step S7).

[0034] In the cutting step, as shown in FIG. 9, while the wafer 10 is rotated on the holding table 50, a laser beam LB is irradiated onto the cutting line 19 from the surface 11 side of the wafer 10 via the condenser 121 of the laser unit 120, and the wafer 10 is cut along the cutting line 19 by ablation processing.

[0035] As a result, a ring-shaped cutting groove 191 is formed in a portion corresponding to the cutting line 19, and the wafer 10 is separated into a circular wafer W (see FIG. 10 ) including the recess 17 on the back surface 16 and the device region 12 on the front surface 11, and an annular member including the ring-shaped reinforcing portion 18 on the back surface 16 and the peripheral excess region 13 on the front surface 11. At this time, by positioning the suction nozzle 130 near the focal point of the laser beam LB, part of the debris generated by the ablation processing is sucked by the suction nozzle 130, and the remaining debris also adheres to the protective film 40 formed in the target region including the cutting line 19. This makes it possible to prevent debris generated in the cutting step from directly adhering to the front surface 11 of the wafer 10.

[0036] 10 is a diagram showing the ring removing step. After the cutting step is completed, the ring removing step is carried out to remove the ring-shaped reinforcing portion 18 separated from the recess 17 in the cutting step (step S8).

[0037] 10 , the ring removal step is a peeling step in which a support table 140 and a separator 150 are used to insert a peeling member, a work 154, between the tape 30 of the frame unit U and the ring-shaped reinforcing portion 18, to peel the ring-shaped reinforcing portion 18 from the tape 30. By peeling the ring-shaped reinforcing portion 18 from the tape 30, the portion including the ring-shaped reinforcing portion 18 separated by the cutting groove 191 is removed from the wafer W including the device region 12, and a wafer W including the device region 12 corresponding to the recess 17 can be obtained.

[0038] The holding table 140 has a holding part 141 that is rotatable around a support shaft 142, and in the ring removal step, the recess 17 (back surface 16) of the wafer 10 is suction-held on the lower surface of the holding part 141. Meanwhile, the frame 20 of the frame unit U is supported by a frame support part 155. The separator 150 has a frame support part 155 on a support substrate 153 connected to a movable piece 152 that moves up and down in the Z-axis direction by a feed unit 151. The frame support part 155 has a housing 1551 and a sphere 1552 rotatably supported by the housing 1551, and the sphere 1552 supports the frame 20. The separator 150 further has a pair of tops 154 on the support substrate 153. The tops 154 have an inverted truncated cone shape with a lower surface smaller than an upper surface 1541, and are supported by the support substrate 153 to be rotatable around a rotation axis in the Z-axis direction. The pair of pieces 154 can be moved apart or towards each other by a feed unit (not shown).

[0039] In the ring removal step, the feed unit 151 is controlled so that the upper end of the ring-shaped reinforcing portion 18 of the wafer 10 held by the separator 150 roughly coincides with the upper surface 1541 of the piece 154, and then the pair of pieces 154 are brought closer to each other, thereby inserting the side surface 1542 of the piece 154 between the tape 30 and the ring-shaped reinforcing portion 18. This causes the ring-shaped reinforcing portion 18 to peel off from the tape 30, and the portion including the ring-shaped reinforcing portion 18 falls into the disposal section 160. The portion including the ring-shaped reinforcing portion 18 that has fallen into the disposal section 160 is collected into a dust box 162 by a belt conveyor 161.

[0040] If a protective film is attached to the side surface of the wafer 10 (the portion including the ring-shaped reinforcing portion 18), the protective film will also adhere to the top 154. If a protective film is attached to the top 154, there is a risk that excessive force will be applied locally to the wafer 10 when the top 154 ​​is inserted, which is undesirable. Furthermore, if the protective film that has wrapped around to the side surface peels off when the top 154 ​​is inserted, debris generated by the impact of the fall will float inside the device and may adhere to unexpected parts of the wafer W, contaminating the wafer W. In the drying step described above, a configuration in which gas is supplied from the radially outer side toward the inner side is desirable because it can suppress such inconveniences.

[0041] 11 is a diagram showing the dividing step. After the ring removing step is completed, a dividing step is performed in which the wafer W obtained by the ring removing step is divided to manufacture a plurality of device chips (step S9).

[0042] In the dividing step, first, the wafer W obtained in the ring removing step is integrated with a frame F using a tape T to create a frame unit U, and the frame unit U is held by a holding table 170. More specifically, as shown in FIG. 11, with the frame F clamped by a frame holding part 172, the wafer W is suction-held by a wafer holding part 171 via the tape T. Thereafter, the wafer W is divided into a plurality of chips C by a cutting unit 180. More specifically, the wafer W is cut and divided along the intended dividing lines 15 (see FIG. 2) by a cutting blade 181 rotating around a spindle 182. In this way, a plurality of chips C are manufactured.

[0043] As described above, according to the wafer processing method and device chip manufacturing method of this embodiment, the wafer is cut with a laser after it is confirmed by inspection that a protective film has been formed in the target area. Therefore, it is possible to reliably prevent debris generated during ablation processing using a laser from adhering to the wafer. Therefore, various problems associated with debris adhesion can be avoided in advance.

[0044] (Second embodiment) Fig. 12 is a flowchart showing the method for manufacturing a device chip according to this embodiment. The method for manufacturing a device chip according to this embodiment shown in Fig. 12 is a method for manufacturing device chips by dividing a wafer processed using the wafer processing method according to this embodiment. Steps S11 to S18 of the method for manufacturing a device chip according to this embodiment constitute the wafer processing method according to this embodiment.

[0045] The device chip manufacturing method according to this embodiment is similar to the method according to the first embodiment in that a cutting step is performed if the chip passes the inspection performed in the inspection step. However, it differs from the method according to the first embodiment in that the inspection step is performed after the drying step. Focusing on the differences, the device chip manufacturing method according to this embodiment and the wafer processing method performed in the device chip manufacturing method will be described.

[0046] When the manufacturing process of the device chip using the manufacturing method of the device chip shown in Fig. 12 is started, first, a holding step and a protective film forming step are performed (steps S11 and S12). The processes performed in the holding step and the protective film forming step are as described above in the first embodiment with reference to Fig. 4. Then, a drying step is performed (step S13). The process performed in the drying step is as described above in the first embodiment with reference to Fig. 8.

[0047] After the drying step is completed, an inspection step is performed (step S14). The inspection step is similar to the inspection step described above in the first embodiment with reference to Fig. 6 in that an image of the front surface 11 of the wafer 10 is acquired by the imaging unit 90 arranged on the front surface 11 side of the wafer 10, and the protective film 40 is inspected based on the acquired image. However, the inspection content is different.

[0048] In the inspection step according to the present embodiment, in addition to the inspection of whether or not the protective film 40 is formed on the target area, which is performed in the inspection step according to the first embodiment (step S3 in FIG. 1), an inspection is also performed to see whether or not the protective film 40 is dry. This is because a dry protective film 40 is suppressed from moving, deforming, dropping, etc., and is therefore desirable in that it is more certain that the protective film is formed on the target area at the time the cutting step is performed.

[0049] If the imaging unit 90 is a color camera, whether the protective film 40 is dry can be determined by whether interference fringes are present on the protective film 40. When the protective film 40 is not dry and remains liquid, the surface height of the protective film 40 is approximately uniform, making interference fringes unlikely to occur. In contrast, when the protective film 40 is sufficiently dry during the drying step, the thickness of the protective film 40 changes due to contact with gas, making interference fringes likely to occur. More specifically, the gas flow velocity is fast and the gas impinges on the protective film 40 with strong force near the air supply unit 110, which is the gas supply source, making the protective film 40 thinner. In contrast, the gas flow velocity decreases with increasing distance from the air supply unit 110, making the gas impinge on the protective film 40 with weaker force. Therefore, the reduction in the thickness of the protective film 40 is smaller, resulting in a thicker protective film 40 than the portion closer to the air supply unit 110. In this way, the thickness of the dried protective film 40 varies slightly depending on the location, and interference fringes occur due to the difference in thickness. As such, the likelihood of interference fringes occurring differs between dry and dry areas, and it is possible to determine whether or not protective film 40 is dry by detecting interference fringes from a color image captured by a color camera. Note that it is not necessarily required that the entire protective film 40 formed on surface 11 is dry. However, it is desirable that protective film 40 formed in the target area is dry. Therefore, in the inspection step, it is desirable to inspect by image processing whether the range in which interference fringes appear covers the target area.

[0050] If the inspection is not passed due to a defective area where the protective film 40 is not formed in the target area (YES in step S15), a cleaning step (step S16) is performed to wash away the protective film formed on the surface 11, and then the above-mentioned processing is repeated again from the protective film forming step. Note that the cleaning step may be omitted, and if the inspection is not passed, a new protective film may be formed on top of the protective film that has already been partially formed in the protective film forming step. On the other hand, if the inspection is not passed due to a drying defect where the protective film 40 is not sufficiently dried (YES in step S17), the above-mentioned processing is repeated again from the drying step. In other words, drying time is added.

[0051] If the inspection is passed (step S17 NO), the cutting step (step S18), the ring removal step (step S19), and the division step (step S20) are performed to manufacture device chips. The processes from step S18 to step S20 are the same as steps S7 to S9 in FIG. 1.

[0052] As described above, according to the wafer processing method and device chip manufacturing method of this embodiment, the wafer is cut with a laser after it is confirmed that a protective film has been formed in the target region and that the formed protective film has sufficiently dried. Therefore, it is possible to more reliably prevent debris generated during ablation processing using a laser from adhering to the wafer.

[0053] (Third embodiment) Fig. 13 is a flowchart showing the method for manufacturing a device chip according to this embodiment. The method for manufacturing a device chip according to this embodiment shown in Fig. 13 is a method for manufacturing device chips by dividing a wafer processed using the wafer processing method according to this embodiment. Steps S21 to S29 of the method for manufacturing a device chip according to this embodiment constitute the wafer processing method according to this embodiment.

[0054] The device chip manufacturing method according to this embodiment is similar to the method according to the above-described embodiment in that a cutting step is performed if the device chip passes the inspection performed in the inspection step. However, it differs from the method according to the above-described embodiment in that the inspection step is performed after the protective film forming step and after the drying step. Below, we will explain the device chip manufacturing method according to this embodiment and the wafer processing method performed in the device chip manufacturing method, focusing on the differences.

[0055] The processes from step S21 to step S26 in Fig. 13 are the same as the processes from step S1 to step S6 in Fig. 1. After the drying step in step S26 is completed, an inspection step is performed to check whether or not the protective film 40 is dry (step S27). The inspection performed in step S27 is the same as the inspection to check whether or not the protective film 40 is dry, which is one of the inspections performed in step S14 in Fig. 12.

[0056] If the protective film 40 is not sufficiently dried and does not pass the inspection in step S27 (NO in step S28), the above-described process is repeated from the drying step onwards. That is, an additional drying time is added.

[0057] If the inspection in step S27 is passed (step S28 YES), the cutting step (step S29), the ring removal step (step S30), and the division step (step S31) are performed to manufacture device chips. The processes in steps S29 to S31 are the same as those in steps S7 to S9 in FIG. 1.

[0058] As described above, according to the wafer processing method and device chip manufacturing method of this embodiment, similar to the second embodiment, the wafer is cut with a laser after it is confirmed that a protective film has been formed in the target region and that the formed protective film has sufficiently dried. Therefore, it is possible to more reliably prevent debris generated by ablation processing using a laser from adhering to the wafer.

[0059] The embodiments of the present invention are not limited to the above-described embodiments, and may be variously modified, substituted, or altered without departing from the spirit and scope of the technical concept of the present invention. Furthermore, if the technical concept of the present invention can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical concept of the present invention. Some of the steps described in the above-described embodiments may be omitted, and new steps may be added.

[0060] In the above-described embodiment, the inspection step is performed to check whether the formation area of ​​the protective film 40 is appropriate and whether the protective film 40 is dry. However, the inspection step is not limited to this. The inspection step may be performed on the protective film 40, and any inspection may be performed. For example, the thickness of the protective film 40 may be inspected. Furthermore, data on the protective film 40 obtained in the inspection step may be recorded to ensure traceability. The recorded data is not limited to inspection results and data related thereto, and may also include any measurement results that are not directly related to the inspection.

[0061] In the above-described embodiment, an example was shown in which an image was acquired by the imaging unit 90 and the protective film 40 was inspected based on the acquired image, but the inspection performed in the inspection step is not limited to being performed based on an image. The protective film 40 may also be inspected using the detection results of any sensor.

[0062] In the above-described embodiment, an example has been shown in which the wafer 10 is cut by a laser from the back surface 16 side on which the ring-shaped reinforcing portion 18 is formed, but the wafer 10 may be cut not only from the back surface 16 side but also from the front surface 11 side. The protective film 40 may be formed on the surface that is irradiated with the laser beam. [Industrial Applicability]

[0063] As described above, the wafer processing method and device chip manufacturing method of the present invention are useful in that they can prevent the adhesion of debris generated by laser ablation processing. [Explanation of symbols]

[0064] 10, W: wafer, 11: front surface, 12: device area, 13: peripheral excess area, 14: device, 15: planned division line, 16: back surface, 17: recess, 18: ring-shaped reinforcement part, 19: planned cutting line, 20, F: frame, 30, T: tape, 40, 41, 42, 43: protective film, 50, 140, 170: holding table, 51, 141: holding part, 52, 142: support shaft, 60: coating device, 61: nozzle 75: Water, 80: Lifting device, 90: Imaging unit, 101, 102, 103: Image, 110: Air supply unit, 120: Laser unit, 130: Suction nozzle, 150: Separator, 154: Frame, 160: Disposal section, 180: Cutting unit, 191: Cutting groove, 411, 421, 431: Outer edge, 412, 422, 432: Inner edge, C: Chip, LB: Laser beam, U: Frame unit

Claims

1. A wafer processing method comprising: cutting a wafer having a first surface formed with a recess and a ring-shaped protrusion surrounding the recess, the wafer having a protective member fixed to the first surface, along a boundary between the protrusion and the recess; a holding step of holding the protective member side on a holding table; a protective film forming step of forming a protective film on an area including the boundary of the wafer held on the holding table; an inspection step of inspecting the protective film formed on the wafer; If the wafer passes the inspection in the inspection step, a cutting step of irradiating the boundary with a laser beam after the inspection step to cut the wafer along the boundary. Wafer processing method.

2. If the inspection step does not pass, the protective film forming step is performed again after the inspection step. The wafer processing method according to claim 1 .

3. After the protective film forming step, a drying step is further provided in which a gas is supplied to the protective film to dry the protective film. The wafer processing method according to claim 1 .

4. The drying step includes supplying the gas from the outside to the inside of the wafer. The wafer processing method according to claim 3.

5. After the cutting step, a peeling step is further included in which a peeling member is inserted between the protective member and the protruding portion to peel the protruding portion from the protective member. The wafer processing method according to claim 1 .

6. A method for manufacturing a plurality of device chips, comprising: a holding step of holding a wafer on a holding table with a protective member fixed to a first surface of the wafer, the first surface having a recess and a ring-shaped protrusion surrounding the recess; a protective film forming step of forming a protective film in an area including a boundary between the convex portion and the concave portion of the wafer held on the holding table; an inspection step of inspecting the protective film formed on the wafer; a cutting step of irradiating a laser beam onto the boundary after the inspection step to cut the wafer along the boundary if the inspection step passes; a dividing step of dividing the area corresponding to the recessed portion to manufacture a plurality of device chips after the cutting step. A method for manufacturing a device chip.

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