Wafer management method

Abstract

To provide a wafer management method that can solve the problem of difficulty in aligning a wafer during processing and inspection performed in later processes.SOLUTION: A method includes a step of forming division starting points along the planned division lines of a wafer 10, a protective member providing step of providing a protective member T on the front surface of the wafer, a backside grinding step of grinding the backside 10b of the wafer to thin it and dividing the wafer into individual device chips 12' from the division starting points, and a transport step of transporting the wafer divided into individual device chips and held together by the protective member to the next process. A rotary encoder 43 and a camera 81 for capturing images of the wafer are provided on a table 41 used in the backside grinding step and steps following the backside grinding step.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a method for managing a wafer having a device region formed on a surface thereof by partitioning a plurality of devices by planned division lines, a peripheral surplus region surrounding the device region, and a notch formed in the peripheral surplus region to indicate an orientation. [Background technology]

[0002] A wafer has a number of devices such as ICs and LSIs formed on its front surface along planned dividing lines. The back surface is ground by a grinding machine to form the wafer into a specified thickness. The wafer is then divided into individual device chips by a cutting machine and laser processing machine. These chips are then used in electrical devices such as mobile phones and personal computers.

[0003] Also, a technology has been proposed in which half-cut grooves are formed on the front surface of the wafer by a cutting device along the intended dividing lines before grinding the back surface of the wafer, and then a protective tape is placed on the front surface of the wafer and the back surface of the wafer is ground by a grinding device to expose the half-cut grooves on the back surface of the wafer, thereby dividing the wafer into individual device chips (see, for example, Patent Document 1).

[0004] Furthermore, a technology has been proposed in which, before grinding the back surface of the wafer, a laser beam of a wavelength that is transparent to the wafer is irradiated from the back surface corresponding to the planned dividing lines formed on the front surface of the wafer by a laser processing device by positioning a focal point inside the wafer to form a modified layer, and then the back surface of the wafer is ground by a grinding device to divide the wafer into individual device chips starting from the planned dividing lines along which the modified layer has been formed (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-220602 A [Patent Document 2] JP 2017-017290 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, a notch indicating a reference orientation for processing is formed on the outer periphery of a wafer, and alignment is performed based on the notch during processing and inspection of the wafer. However, when the back surface of the wafer is ground to thin it and the wafer is divided into individual device chips, relatively small, roughly triangular chips present on the outer periphery scatter, and the chipped portions of the scattered chips become indistinguishable from the notch. In addition, the notch itself may be damaged, which makes it difficult to align the wafer during processing and inspection performed in the process after the back surface is ground and the wafer is divided into individual device chips.

[0007] The present invention has been made in consideration of the above-mentioned facts, and its main technical object is to provide a wafer management method that can solve the problem that, when the back surface of the wafer is ground and divided into individual device chips, it becomes difficult to align the wafer in the processing and inspection carried out in the subsequent steps, even if relatively small, approximately triangular chips present on the outer periphery are scattered or the notch is damaged. [Means for solving the problem]

[0008] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a method for managing a wafer having a device region formed on a surface thereof by partitioning a plurality of devices by a division line, a peripheral surplus region surrounding the device region, and a notch formed in the peripheral surplus region to indicate an orientation, the method comprising: a division start point forming step of forming a division start point along the division line; a protective member disposing step of disposing a protective member on the surface of the wafer; a backside grinding step of supporting the protective member side on a table and grinding the backside of the wafer to thin it, and dividing the wafer into individual device chips from the division start points formed on the division line; and a process of transferring the wafer divided into individual device chips and held together by the protective member to a subsequent process. a transport step of transporting a wafer held on a table, the table including the table used in the back grinding step and the tables used in the steps after the back grinding step being provided with rotary encoders and cameras for imaging the wafer held on the tables, and after the wafer is divided into individual device chips by the back grinding step and a plurality of division lines are formed on the back surface, a table rotation step of rotating the table so that the notches formed in the wafer by the rotary encoder face in a desired direction, and a rotation correction step of imaging the wafer and rotating the table to position the division line at an angle closest to the desired direction parallel to the desired direction.

[0009] In the division starting point forming step, it is preferable to position a cutting blade on the division line formed on the front surface of the wafer to form a half-cut groove as the division starting point, then to perform the protective member providing step, and in the back surface grinding step, to expose the half-cut groove on the back surface to divide the wafer into individual device chips. It is also preferable to perform the protective member providing step, and then to irradiate the back surface of the wafer with a laser beam having a wavelength that is transparent to the wafer, positioning a focal point of the beam inside the division line to form a modified layer as the division starting point, and in the back surface grinding step, to grind the back surface of the wafer to thin it and generate cracks from the modified layer to the front surface to divide the wafer into individual device chips. Effect of the Invention

[0010] The method for managing a wafer of the present invention is a method for managing a wafer having a device region formed on the front surface by dividing a plurality of devices by a division line, a peripheral surplus region surrounding the device region, and a notch formed in the peripheral surplus region to indicate an orientation, and is configured to include a division start point forming step of forming a division start point along the division line, a protective member disposing step of disposing a protective member on the front surface of the wafer, a back surface grinding step of supporting the protective member side with a table and grinding the back surface of the wafer to thin it, and dividing the wafer into individual device chips from the division start points formed on the division line, and a transport step of transporting the wafer divided into individual device chips and held together by the protective member to a subsequent step, and the table used in the back surface grinding step and other devices used in the steps subsequent to the back surface grinding step are also included. The wafer grinding process includes a table rotation process in which the table is rotated so that the notch formed in the wafer by the rotary encoder faces a desired direction after the wafer is divided into individual device chips by the back grinding process and a plurality of division lines are formed on the back surface, and a rotation correction process in which the wafer is imaged and the table is rotated so that the division line having the angle closest to the desired direction is parallel to the desired direction, so that even if the relatively small, approximately triangular chips present on the outer periphery of the wafer are scattered and chipped portions are generated in a plurality of places by the back grinding process, and the position of the notch cannot be clearly grasped, the position of the notch can be reliably directed in the appropriate direction in a subsequent process. Therefore, the problem of difficulty in aligning the wafer in the processing, inspection, etc. performed in the subsequent processes can be solved. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a perspective view of a wafer to be managed. [Diagram 2]FIG. 1A is an oblique view showing how a wafer is placed on a chuck table of a cutting device; FIG. 1B is an oblique view showing how a half-cut groove is formed by a division start point forming process performed by the cutting device; and FIG. 1C is an enlarged partial cross-sectional view showing the shape of the half-cut groove. [Diagram 3] FIG. 11 is a perspective view showing an embodiment of a holding member disposing step. [Figure 4] FIG. 11 is a perspective view showing another embodiment of the holding member disposing step. [Diagram 5] FIG. 1A is an oblique view showing how a wafer is placed on a chuck table of a laser processing apparatus; FIG. 1B is an oblique view showing how a modified layer is formed by a splitting starting point formation process; and FIG. 1C is an enlarged partial cross-sectional view showing the shape of the modified layer. [Figure 6] 1 is a perspective view showing a manner in which a wafer is placed on a table of a grinding device that performs a back grinding step. FIG. [Figure 7] FIG. 2 is a perspective view showing a mode of detecting the direction of a notch of a wafer in a grinding apparatus. [Figure 8] FIG. 11 is a perspective view showing a mode in which a back grinding step is carried out. [Figure 9] FIG. 11 is a perspective view showing an aspect in which a table rotating step and a rotation correcting step are performed after a back surface grinding step is performed. [Figure 10] FIG. 11 is a perspective view showing an embodiment of a conveying step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a wafer management method according to the present invention will be described in detail with reference to the accompanying drawings.

[0013] An example of a wafer to be managed in the wafer management method of this embodiment is shown in Fig. 1. The wafer 10 shown in Fig. 1 is, for example, a silicon wafer, and has a front surface 10a and a back surface 10b. The wafer 10 has a device region 16 formed on the front surface 10a by dividing a plurality of devices 12 by planned division lines 14, a peripheral surplus region 17 surrounding the device region 16, and a notch 19 formed in the peripheral surplus region 17 and provided at a position that serves as a reference for the orientation when processing or inspecting the wafer 10.

[0014] (Split starting point formation process) First, when carrying out the wafer management method of this embodiment, a splitting start point forming step is carried out to form splitting start points along the planned splitting lines 14 of the illustrated wafer 10. The splitting start points formed by the splitting start point forming step serve as start points when the wafer 10 is split into individual device chips by grinding the back surface 10b of the wafer 10 to a desired thickness in a back surface grinding step carried out later, and are formed, for example, according to the following procedure.

[0015] Once the unprocessed wafer 10 described based on FIG. 1 is prepared, it is transferred to a cutting device 20 (only a part of which is shown) shown in FIGS. 2(a) and (b). The cutting device 20 includes a chuck table 21 shown in FIG. 2(a) and a cutting means 22 shown in FIG. 2(b). The chuck table 21 includes an adsorption chuck 21a made of a breathable material and a frame 21b surrounding the adsorption chuck 21a. The chuck table 21 is connected to a suction means via the frame 21b, and by operating the suction means, a suction force is generated on the upper surface of the adsorption chuck 21a. The chuck table 21 is configured to be rotatable by a rotary drive means (not shown), and includes an X-axis feed means (not shown) that feeds the chuck table for processing in the direction indicated by the arrow X in FIG. 2(b). The cutting means 22 includes a spindle housing 23 disposed in the Y-axis direction indicated by the arrow Y in the drawing, which is perpendicular to the X-axis direction, a spindle 24 rotatably held by the spindle housing 23, an annular cutting blade 25 held at the tip of the spindle 24, and a blade cover 26 that covers the cutting blade 25, and also includes a Y-axis feed means (not shown) that indexes and feeds the cutting blade 25 in the Y-axis direction. The spindle 24 is driven to rotate by a motor (not shown).

[0016] When the wafer 10 is transported to the cutting device 20, as shown in FIG. 2(a), the wafer 10 is placed on the chuck table 21 of the cutting device 20 with the front surface 10a of the wafer 10 facing upward, and the suction means is operated to hold the wafer 10 by suction. Next, by performing alignment using an alignment means (not shown), the predetermined division line 14 of the wafer 10 is aligned in the X-axis direction, and the cutting blade 25 is aligned. Next, as shown in FIG. 2(b), the cutting blade 25 rotated in the direction indicated by the arrow R1 is positioned on the division line 14 aligned in the X-axis direction, and cuts into the wafer 10 from the front surface 10a side, while the chuck table 21 is processed and fed in the X-axis direction, and as shown in FIG. 2(c), a half-cut groove 100 is formed as a division starting point in the subsequent back grinding process. The depth of the half-cut groove 100 is set to a depth that is exposed when the back surface 10b of the wafer 10 is ground to a desired thickness in the back grinding process described later.

[0017] Furthermore, the Y-axis feed means is operated to position the cutting blade 25 of the cutting means 22 on the dividing line 14 adjacent in the Y-axis direction to the dividing line 14 on which the half-cut groove 100 is formed and on which the half-cut groove 100 is not formed, and the half-cut groove 100 is formed in the same manner as described above. By repeating these steps, the half-cut grooves 100 are formed along all dividing lines 14 along the X-axis direction. Next, the chuck table 21 is rotated 90 degrees, and the direction of the dividing line 14 perpendicular to the direction in which the half-cut groove 100 was previously formed is aligned with the X-axis direction, and the above-mentioned cutting process is performed on all dividing lines 14 newly aligned with the X-axis direction, and the above-mentioned half-cut grooves 100 are formed along all dividing lines 14 formed on the wafer 10. With the above, the dividing start point forming process is completed.

[0018] (Protective member installation process) After the above-mentioned division start point forming step is performed, as shown in Fig. 3, a protective tape T is attached to the front surface 10a of the wafer 10, and the wafer is integrated as shown in the lower part of the figure. The protective tape T functions as a protective member that protects the front surface 10a of the wafer 10 in the back grinding step that is performed later. This completes the protective member disposing step.

[0019] The dividing start point forming step and the protective member providing step of the present invention are not limited to the above-mentioned embodiment. Another embodiment of the dividing start point forming step and the protective member providing step will be described with reference to Figs.

[0020] Once the unprocessed wafer 10 described based on Figure 1 has been prepared, as shown in Figure 4, a protective tape T that functions as a protective member is attached to the surface 10a of the wafer 10 before the division starting points are formed, thereby integrating the surface 10a of the wafer 10 (protective member disposing process).

[0021] Next, the wafer 10 that has been subjected to the protective member disposing process is transferred to a laser processing device 30 (only a part of which is shown) shown in Figures 5(a) and (b). The laser processing device 30 includes a chuck table 31 shown in Figure 5(a) and a laser beam application means 32 shown in Figure 5(b). The chuck table 31 includes an adsorption chuck 31a made of a breathable material that constitutes a holding surface, and a frame portion 31b that surrounds the adsorption chuck 31a. The chuck table 31 is connected to a suction means via the frame portion 31b, and a suction force is generated on the holding surface by operating the suction means. The chuck table 31 is configured to be freely rotatable by a rotary drive means (not shown), and includes an X-axis feed means that feeds the chuck table for processing in the direction indicated by the arrow X in the figure, and a Y-axis feed means that indexes and feeds in the Y-axis direction perpendicular to the X-axis direction (both not shown). The laser beam application means 32 is a means for applying a laser beam LB having a wavelength that is transparent to the wafer 10 to the wafer 10 held on the chuck table 31, and is equipped with a condenser 33 for collecting and applying the laser beam LB.

[0022] The wafer 10 transported to the laser processing device 30 is placed on the chuck table 31 with the back surface 10b of the wafer 10 facing upward and the protective tape T facing downward, as shown in Fig. 5(a), and the suction means is operated to hold the wafer 10 by suction. Once the wafer 10 is held by the chuck table 31 by suction, alignment is performed using an alignment means equipped with an infrared camera (not shown) to detect the positions of the division lines 14 formed on the front surface 10a, and the wafer 10 is rotated together with the chuck table 31 by the rotary drive means to align the division lines 14 in a predetermined direction with the X-axis direction. Position information of the detected division lines 14 is stored in a control means (not shown).

[0023] Based on the position information detected by the above alignment, the condenser 33 of the laser beam application means 32 is positioned at the processing start position of the dividing line 14 in a predetermined direction, and the condensing point of the laser beam LB is positioned inside the dividing line 14 of the wafer 10 from the back surface 10b side of the wafer 10 as shown in FIG. 5(b), and the wafer 10 is processed and fed in the X-axis direction to form a modified layer 110 inside the wafer 10 as shown in FIG. 5(c). After the modified layer 110 is formed as shown in the figure, the wafer 10 is indexed and fed in the Y-axis direction by the interval of the dividing line 14, and the unprocessed dividing line 14 adjacent in the Y-axis direction is positioned directly under the condenser 33. Then, in the same manner as described above, the condensing point of the laser beam LB is positioned inside the dividing line 14 of the wafer 10 to irradiate, and the wafer 10 is processed and fed in the X-axis direction to form the modified layer 110. Similarly, the wafer 10 is processed and fed in the X-axis direction and the Y-axis direction to form modified layers 110 inside along all of the planned dividing lines 14 along the X-axis direction.

[0024] Next, the wafer 10 is rotated 90 degrees to align the unprocessed division lines 14 perpendicular to the division lines 14 on which the modified layers 110 have already been formed in the X-axis direction. Then, the remaining division lines 14 are irradiated with the laser beam LB by positioning the focal point in the same manner as described above, and the modified layers 110 that will be the division start points in the subsequent back grinding process are formed along the insides of all the division lines 14 as shown on the right side of FIG. 5(b) (division start point forming process). Note that the wafer on which the modified layers 110 that will be the division start points are formed along the insides of the division lines 14 is referred to as the wafer 10' in order to distinguish it from the wafer 10 on which the half-cut grooves 100 are formed. In this way, when forming the modified layers 110 that will be the division start points along the insides of the division lines 14, the protective member disposing process is performed first, and the division start point forming process is performed later, as described above.

[0025] As described above, after the protective member providing step and the dividing start point forming step are performed, a back surface grinding step is performed in which the back surface 10b of the wafer 10 or the wafer 10' is ground to thin it, and the wafer 10 is divided into individual device chips from the dividing start points (half-cut grooves 100 or modified layers 110) formed along the intended dividing lines 14. The back surface grinding step will be described with reference to Figs. 6 to 8.

[0026] (Back grinding process) A grinding device 40 (only a part of which is shown) used to carry out the back grinding process is shown in Figures 6 to 8. Figure 6 shows a table 41 that supports the wafer 10 and is configured to be freely rotatable, Figure 7 shows a camera 81 that images the wafer 10 supported on the table 41, and Figure 8 shows grinding means 45 that grinds the back surface 10b of the wafer 10 supported on the table 41.

[0027] 6, the table 41 includes an adhesion chuck 41a made of a breathable material, a frame 41b surrounding the adhesion chuck 41a, a support column 42 supporting the frame 41b from its underside, a rotary encoder 43 formed on the lower end of the support column 42 for detecting the rotation angle of the table 41, and a rotation drive means (not shown) for rotating the table 41. The rotary encoder 43 is provided with a read head 44 for reading the scale 43a formed on the rotary encoder 43, and a signal indicating the rotation angle of the table 41 read by the read head 44 is transmitted to and stored in a control means 80 shown in FIG.

[0028] 8, the grinding means 45 includes a rotating spindle 45a rotated by a rotary drive means (not shown), a wheel mount 45b attached to the lower end of the rotating spindle 45a, and a grinding wheel 45c attached to the lower surface of the wheel mount 45b, and a plurality of grinding stones 45d are annularly disposed on the lower surface of the grinding wheel 45c. The grinding means 45 is moved up and down by a lifting means (not shown).

[0029] 6, when performing the back grinding step, the wafer 10 or wafer 10' which has been subjected to the protective member providing step and the splitting start point forming step is transported to the grinding device 40, placed on the suction chuck 41a of the table 41 with the protective tape T side facing downward, and supported by operating a suction means (not shown). Note that in the following explanation, a case will be explained in which the wafer 10 in which the half-cut grooves 100 which serve as splitting start points are formed along the intended split line 14 in the splitting start point forming step is supported.

[0030] After the wafer 10 is supported on the table 41, as shown in FIG. 7, a camera 81 is positioned at a position where the outer peripheral region of the wafer 10 on the table 41 can be imaged, and the wafer 10 is imaged. The image obtained by the image capture is displayed on the display means 82 via the control means 80. The display means 82 shows a direction line 82a indicating a predetermined direction (up and down direction). While the wafer 10 is being imaged by the camera 81, the rotation drive means (not shown) is operated to adjust the table 41 in the rotation direction indicated by the arrow R2, and the direction of the notch 19 indicating the orientation of the wafer 10 is made to coincide with the desired direction, i.e., the above-mentioned direction line 82a, as shown in the display means 82 in FIG. 7. Then, the scale 43a of the rotary encoder 43 at this time is read by the read head 44 and transmitted to the control means 80, and the rotation angle of the table 41 in the state where the notch 19 faces the desired direction coinciding with the direction line 82a is stored. The method of storing the rotation angle of the table 41 in a state where the notch 19 faces the desired direction coinciding with the direction line 82a is not limited to the above-mentioned method of capturing an image with the camera 81, adjusting the table 41 in the rotation direction indicated by the arrow R2, and detecting the rotation angle of the table 41 with the rotary encoder 43. For example, when the wafer 10 is transported and placed on the table 41 of the grinding device 40, if it is clear that the wafer 10 will be placed with the notch 19 of the wafer 10 facing the desired direction, the rotation angle of the table 41 when the wafer 10 is placed and supported on the table 41 may be read by the rotary encoder 43 and stored in the control means 80.

[0031] Next, as shown in FIG. 8, backside grinding is performed on the backside 10b of the wafer 10. Specifically, the spindle 45a of the grinding means 45 is rotated in the direction indicated by the arrow R3 in FIG. 8 at, for example, 6000 rpm, while the chuck table 41 is rotated in the direction indicated by the arrow R4 at, for example, 300 rpm. Then, while grinding water is supplied onto the backside 10b of the wafer 10 by a grinding water supplying means (not shown), a grinding feed means (not shown) is operated to lower the grinding means 45 in the direction indicated by the arrow R5 (downward), and the grinding wheel 45d is brought into contact with the backside 10b of the wafer 10, and the grinding is fed at a grinding feed rate of, for example, 1 μm / sec. At this time, grinding can be carried out while measuring the thickness of the wafer 10 by a contact or non-contact measuring gauge (not shown), and the backside 10b of the wafer 10 is ground and thinned by a predetermined amount. 9, the half-cut grooves 100 are exposed on the back surface 10b side of the wafer 10, forming division lines 100', and the wafer 10 is divided into individual device chips 12', completing the back surface grinding step. After the back surface grinding step has been performed in this manner, the grinding means 45 is stopped, and cleaning, drying steps, etc. are appropriately performed.

[0032] After the above-described back grinding process is performed, the wafer 10 divided into individual device chips 12' and held together by the protective tape T is transported to the next process. At this time, in order to transport the wafer 10 to the next process with the notch 19 facing in the desired direction, a table rotation process and a rotation correction process, which will be described below, are performed.

[0033] (Table rotation process) When the wafer 10 is divided into individual device chips 12' by carrying out the back grinding process described above, chipped portions 10c are generated at multiple locations, where relatively small, approximately triangular chips existing on the outer periphery of the wafer 10 are scattered, as shown in FIG. 9. The chipped portions 10c may have a shape very similar to that of the notch 19, and it may be difficult to capture the notch 19 with the camera 81 and orient the notch 19 in a desired direction based on the notch 19. In this embodiment, as described above, before carrying out the back grinding process, the rotation angle of the table 41 is detected by the rotary encoder 43 with the notch 19 positioned in a desired direction, and is transmitted to and stored in the control means 80. Based on the information on the rotation angle of the table 41 stored in the control means 80, the table 41 is rotated by a rotary drive means (not shown) to rotate the table 41 so that the notch 19 formed on the wafer 10 is oriented in a desired direction. After the table rotation step is thus performed, an image of the outer periphery of the wafer 10 captured by the camera 81 is displayed on the display means 82 shown in the upper left of FIG.

[0034] By carrying out the above-described table rotation process, the direction of the notch 19 is positioned in an approximately desired direction, and is brought into a state of being approximately aligned with the direction line 82a displayed on the display means 82, as shown in the figure. However, the direction of the notch 19 and the direction line 82a displayed on the display means 82 may not exactly match, as shown in the figure, because there is a limit to the accuracy of the rotation angle that can be read by the rotary encoder 43. Therefore, in this embodiment, a rotation correction process described below is carried out.

[0035] (Rotation correction process) Based on the image captured by the camera 81 on the display means 82, a dividing line 100' that forms the closest angle with respect to the direction line 82a indicating the desired direction is detected. In FIG. 9, the direction of the dividing line 100' is indicated by a two-dot chain line Q. Next, the table 41 is rotated in the direction indicated by the arrow R6 in FIG. 9 so that the dividing line 100' is parallel to the direction line 82a indicating the desired direction. The angle at which the table 41 is rotated is, for example, m°. As a result, as shown on the display means 82' shown in the lower left of FIG. 9, the direction of the dividing line 100', i.e., the direction in which the notch 19 is formed, is corrected from a state in which it roughly coincides with the direction of the direction line 82a indicating the desired direction to an exact coincidence, and the rotation correction process is completed.

[0036] (Transportation process) As a result of carrying out the above-mentioned division starting point forming step, protective member disposing step, back grinding step, table rotating step, and rotation correction step, the wafer 10 divided into individual device chips 12' and held together by the protective tape T is supported on the table 41 with the notch 19 accurately aligned with the desired direction. Therefore, as shown in FIG. 10, the wafer 10 supported on the table 41 in the desired direction can be transported to the next step (e.g., pick-up step). When the wafer 10 is transported to the next step, it is sucked and transported by a specified transport means (not shown), for example, a transport arm equipped with a suction means for sucking the wafer 10, and placed on a specified table in the next step. At this time, although the direction of the notch 19 is somewhat deviated, as described above, since the wafer 10 was supported on the table 41 with the notch 19 accurately aligned with the desired direction, the angle when the wafer 10 is placed on the specified table in the next step is approximately aligned with the desired direction.

[0037] In the transport process of the embodiment configured based on the wafer management method of the present invention, the wafer 10 divided into individual device chips 12' and held together by protective tape T is transported through a plurality of processes. A rotary encoder similar to that in the above-described embodiment is provided on a table that supports the wafer 10 and is used in each process where the wafer 10 is transported, and a camera that captures an image of the wafer 10 held on the table is also provided, and each time, the division line 100' closest to the direction of the direction line 82a is positioned parallel to the direction line 82a to accurately match the direction in which the notch 19 is formed with the desired direction.

[0038] As described above, in the wafer management method according to the present invention, the tables used in the back grinding process and the subsequent processes after the back grinding process are provided with the same rotary encoder as described above, as well as a camera for capturing an image of the wafer held on the table. Then, when the wafer 10 divided into individual device chips 12' and held together by the protective tape T is transported to the next process, the table rotation process and the rotation correction process are performed. As a result, even if the relatively small triangular chips present on the outer periphery of the wafer 10 are scattered by the back grinding process and the chipped portions 10c are generated at multiple places, making it difficult to clearly grasp the position of the notch 19, the position of the notch 19 is reliably directed in the desired direction in the subsequent process. This solves the problem that it is difficult to align the wafer 10 in the processing, inspection, and other processes performed in the subsequent processes.

[0039] In the above embodiment, the wafer 10 having the half-cut grooves 100 formed along the dividing lines 14 and functioning as dividing starting points is supported on the table 41 of the grinding device 40, and the back grinding step is performed to expose the half-cut grooves 100 on the back surface 10b to form the dividing lines 100'. However, the back grinding step may be performed by supporting the protective tape T side of the wafer 10' having the modified layer 110 formed along the dividing lines 14 on the table 41. In that case, in the process of grinding the back surface 10b of the wafer 10' to thin it to a desired thickness, cracks are generated from the modified layer 110 formed along the dividing lines 14 to the front surface 10a of the wafer 10', and dividing lines dividing the wafer 10' along the dividing lines 14 are formed on the wafer 10', and the wafer 10' is divided into individual device chips 12'. In this case, as with the wafer 10 described above, relatively small triangular chips present on the outer periphery of the wafer 10' are scattered, causing chipped portions in multiple places, resulting in the same problems as with the wafer 10 described above. However, by carrying out the table rotation process and rotation correction process described above, it is possible to achieve the same effects as in the embodiment described above.

[0040] The starting point of division formed in the dividing starting point forming step of the present invention is not limited to the half-cut groove 100 and modified layer 110 described above. For example, the focusing point of a laser beam having a wavelength absorbed by the wafer 10 may be positioned on the dividing line 14 formed on the front surface 10a of the wafer 10 and irradiated, and the wafer 10 may be processed and fed in the X-axis direction and the Y-axis direction to perform ablation processing to form a laser processed groove, which serves as the starting point of division. In this case, it is preferable to carry out the protective member disposing step after carrying out the dividing starting point forming step. [Explanation of symbols]

[0041] 10: Wafer 10a: surface 10b: Back side 12: Device 12': Device chip 14: Planned division line 16: Device area 17: Surplus outer area 20: Cutting equipment 21: Chuck table 22:Cutting means 23: Spindle housing 24: Spindle 25:Cutting blade 30: Laser processing equipment 31: Chuck table 32: Laser beam irradiation means 33: Concentrator 40: Grinding equipment 41: Table 42: Support pillar 43: Rotary encoder 43a: Scale 44: Read head 45: Grinding means 45a: Rotating spindle 45c: grinding wheel 45d: Grinding wheel 80: Control means 81: Camera 82:Display means 82a: Direction line 100: Half cut groove 100':Dividing line 110: Modified layer

Claims

1. A method for managing a wafer comprising: a device region formed on a surface of the wafer by dividing a plurality of devices into sections by planned division lines; a peripheral surplus region surrounding the device region; and a notch formed in the peripheral surplus region to indicate an orientation, the method comprising the steps of: a division starting point forming step of forming a division starting point along the planned division line; a protective member providing step of providing a protective member on a front surface of the wafer; a backside grinding step in which the protective member side of the wafer is supported on a table, the backside of the wafer is ground to thin the wafer, and the wafer is divided into individual device chips from division starting points formed on the division lines; a transport step of transporting the wafer divided into individual device chips and held together by protective members to a next process; The present invention includes: a table rotation step in which a rotary encoder is provided on tables used in the steps subsequent to the back grinding step, including the table used in the back grinding step, and a camera is provided to capture an image of the wafer held on the table, and after the wafer is divided into individual device chips by the back grinding step and a plurality of division lines are formed on the back surface, the table is rotated by the rotary encoder so that the notches formed in the wafer are oriented in a desired direction; a rotation correction step of imaging the wafer and rotating the table so that the parting line having the angle closest to the desired direction is parallel to the desired direction; The wafer management method includes the steps of:

2. In the dividing start point forming step, a cutting blade is positioned on a dividing line formed on the surface of the wafer to form a half-cut groove as the dividing start point; Thereafter, the protective member disposing step is carried out, 2. The wafer management method according to claim 1, wherein in the back grinding step, the wafer is divided into individual device chips with the half-cut grooves exposed on the back surface.

3. The protective member disposing step is carried out, Then, in the splitting starting point forming step, a focused point of a laser beam having a wavelength that is transparent to the wafer is positioned inside the wafer from the back surface of the wafer corresponding to the intended splitting line, and a modified layer is formed as the splitting starting point; 2. The method for managing a wafer according to claim 1, wherein in the back surface grinding step, the back surface of the wafer is ground to thin it and cracks are generated extending from the modified layer to the front surface, thereby dividing the wafer into individual device chips.

Images